Glossary of technical terms for the use of metallurgical engineers Terms starting with alphabet ‘D’
Glossary of technical terms for the use of metallurgical engineers
Terms starting with alphabet ‘D’
D2D – It very frequently stands for door-to-door in business and sales, or device-to-device / direct-to-device in technology.
Dacron polyester – It is a type of polyester produced through the polymerization of di-methyl terephthalate and ethylene glycol through a condensation reaction, which results in the release of methanol as a by-product. It is a durable, wrinkle-resistant polyester fibre. It is widely used in industrial textiles.
Dahl model – It is a dynamic friction model used in control and mechanical engineering. It modifies traditional static friction (coulomb) models by treating friction as a stress-strain relationship. It specifically simulates hysteretic friction and elastic deformation in the pre-sliding regime.
Dahlquist criterion – It is a rheological rule of thumb defining the necessary conditions for a material to act as a pressure-sensitive adhesive (PSA). It states that for a material to have measurable ‘quick tack’ (instant adhesion upon light contact), its shear storage modulus (G’) is to be less than 0.3 mega-pascals at a bonding frequency of 1 hertz.
Daily heat storage – It refers to the method of capturing and retaining thermal energy for use within a 24-hour cycle. It is mainly used to balance daily energy supply and demand, storing excess heat during peak production hours and releasing it when needed for building space heating or industrial processes.
D’Alembert’s paradox – It is the phenomenon where, in the theoretical study of an ideal fluid flow around a cylinder, no net force acts on the cylinder because of symmetrical pressure distribution, despite the expectation of resistance in real fluids.
D’Alembert’s principle – It states that an accelerating physical system can be transformed into an equivalent static system of dynamic equilibrium by adding a fictitious inertia force acting opposite to the direction of acceleration. It re-frames Newton’s second law (F = ma) into the equilibrium equation (F – ma = 0).
Dall flow tube – It is a differential pressure flow meter that measures fluid velocity by constricting flow and creating a pressure drop. Acting as a hybrid between a venturi tube and an orifice plate, it generates a high differential pressure while retaining the lowest permanent energy loss among standard differential pressure devices.
Dall tube flow meter – It is a modified, shortened version of a venturi meter which measures fluid flow by creating a differential pressure. It combines features of a venturi tube and an orifice plate, delivering high pressure differentials with exceptionally low permanent energy / head loss.
Dalton (Da) – It is also known as unified atomic mass unit (u). It is a unit of mass defined as 1/12 of the mass of a free unexcited atom of carbon-12 at rest. It is approximately equal to the mass of one nucleon.
Dalton’s law – It states that the total pressure exerted by a mixture of non-reacting gases is equal to the sum of the partial pressures of the individual gases. Basically, each gas in a mixture acts independently, and its pressure contribution depends on its concentration.
Dalton’s law of partial pressures – It is a law which states that in a mixture of non-reacting gases, the total pressure exerted is equal to the sum of the partial pressures of the individual gases. It is closely related to the ideal gas laws.
Dam – It is a structure built across a liquid stream for the control of its flow. It is a flow control device which is used in continuous casting tundishes. It is also the boundary support or ridge used to prevent excessive edge bleeding or resin runout of a laminate and to prevent crowning of the bag during cure.
Damage – It is the impairment of the useful life of a part.
Damage accumulation – It refers to the gradual, progressive degradation of a material or structure over time because of the repeated stress, environmental exposure, or discrete events. It is a fundamental concept used to predict when a structure is going to fail. The most common method for calculating damage accumulation is the Palmgren-Miner linear damage rule (frequently referred to as Miner’s rule). This rule states that if a structure undergoes ‘n1’ cycles of stress at an amplitude where it normally takes ‘N1’ cycles to fail, the damage fraction consumed by that stress is ‘n1/N1’.
Damage analysis – It is the forensic process of examining a failed or degraded material, component, or structure to determine the root cause of the damage. The main goal is to identify how and why the failure occurred, preventing future recurrences and guiding repairs or redesigns.
Damage assessment – It consists of a series of steps including observation, evaluation, prioritization, and recordkeeping, necessary for evaluating the extent of damage caused by a disaster. Accurate assessment serves as the foundation for effective disaster redressal and decision-making regarding the repair or disposal of damaged items.
Damage behaviour – It refers to the progressive physical or structural degradation of a material or system under stress, which impairs its optimal performance or load-bearing capacity without necessarily causing immediate, total failure. This behaviour allows for the modeling of how voids, cracks, or fatigue accumulate over time. It involves tracking specific thresholds.
Damage classification – It is the systematic method of categorizing microstructural degradation, structural defects, and material failure modes into descriptive groups. It determines how and why a metal fails by evaluating factors like load, environment, and temperature, directly guiding failure prevention and repair. Main damage classifications are ductile damage, fatigue damage, and creep damage.
Damage condition – It describes any harm, impairment, or physical alteration which degrades an object, material, or system from its initial, optimal state. It indicates a reduction in value, integrity, or functionality, and can occur because of sudden accidents or gradual wear and tear.
Damage constant – It is frequently called damage coefficient. It is a proportionality factor used to quantify how rapidly a material degrades when exposed to radiation. It typically relates the change in a physical property, like carrier life-time or electrical leakage, directly to radiation fluence.
Damage control – It refers to systems, design methodologies, or operational protocols used to limit the cascading effects of a failure or catastrophic event. It prioritizes containing a crisis and maintaining system stability over immediately fixing the root cause.
Damage control design – It is a proactive philosophy focused on limiting structural and functional failure during extreme events. Instead of attempting to prevent all harm, it isolates potential damage to specific, easily repairable components. The main goal is to ensure safety, minimize downtime, and preserve core operational functions.
Damage cost – It refers to the monetary value of harm or loss resulting from an event, such as an accident, disaster, or environmental impact, including costs for repair, replacement, lost earnings, and other related expenses.
Damage criterion – It refers to a set of conditions used to predict the failure of materials, frequently based on factors such as critical stretch, stress, or energy release rates, which indicate when the onset of damage occurs in the material structure.
Damaged composite system – It refers to a composite material or structure whose internal matrix, fibres, or interfaces have suffered deterioration. It uses mathematical ‘damage variables’ in its equations to represent the loss of structural integrity, stiffness, or load-bearing capacity caused by micro-cracking, delamination, or environmental exposure.
Damaged configuration – It is a state in which a material shows damage because of the presence of voids and cracks, affecting its structural integrity and load-bearing capacity. It also refers to a system or application set-up which has become corrupt, incomplete, or incorrectly altered, preventing proper function or secure operation. This frequently leads to boot failures, security vulnerabilities, or service crashes.
Damage development – It is also called damage evolution. It refers to the progressive, cumulative degradation of a material’s physical and mechanical properties over time. It tracks how microscopic defects like cracks, voids, and pores grow under thermo-mechanical stress, ultimately reducing the load-bearing capacity and structural integrity.
Damaged laminate – It refers to the structural or physical compromise in a material constructed from multiple bonded layers. The damage condition of the impacted laminate is normally characterized by the delamination width measured transverse to the loading axis, damage length (measured parallel to the loading axis) or damage area. Other factors which can influence fatigue and static performance are the location of delaminations of different size and shape through the thickness. The impact damage is a function of several variables. These include factors external to the material such as impact energy, velocity and impactor shape.
Damaged plate – It normally refers to any flat structural component (metal, composite, or concrete) used in bridges, or pressure vessels which has suffered from deformation, cracking, or material degradation. It is defined by a loss of flexural rigidity, resulting in reduced load-carrying capacity and altered vibration frequencies.
Damage effect tensor – Itis a mathematical construct in continuum damage mechanics (CDM) used to relate the actual macroscopic stress (Cauchy stress) to the fictitious effective stress in a material. It accounts for the reduction in load-bearing area caused by micro-cracks and voids. Materials lose stiffness and strength as they accumulate micro-defects. To model this without tracking every microscopic crack, engineers use the concept of effective stress, which is the hypothetical stress experienced by the intact, undamaged portions of the material. The damage effect tensor, normally represented as a fourth-order tensor (or a second-order tensor in simpler models), bridges the damaged and undamaged configurations.
Damage entity – It refers to the quantifiable physical degradation of a material, represented by a damage variable (normally ‘D’). It typically ranges from 0 (undamaged) to 1 (complete failure or loss of load-bearing capacity). In continuum mechanics, the specific damage entity is calculated using the effective resisting area ‘D = (A-As)/A’, where ‘A’ is the nominal cross-sectional area and ’As’ is the effective resisting area after accounting for micro-defects and voids.
Damage evolution – It is the progressive degradation of a material’s structural integrity over time. It describes how micro-cracks or voids nucleate and grow under continued stress or environmental conditions, reducing the material’s load-bearing capacity until total failure occurs. In computational engineering and finite element analysis (FEA), a damage evolution law is used to mathematically calculate how this damage spreads. Once a material meets a damage initiation criterion (such as reaching a critical plastic strain), the evolution law determines the rate at which the material’s stiffness softens.
Damage evolution law – It is defined as a mathematical framework which describes the progression of material damage over time, derived from a damage criterion which functions as a scalar value of the thermodynamic force associated with a damage variable. It incorporates parameters such as the initial damage threshold and the kinetics of damage evolution.
Damage initiation – It is the point where a material begins to permanently degrade, transitioning from its pristine state to one with micro-cracks or voids. This threshold is defined by initiation criteria (e.g., stress, strain, or energy limits) that, once exceeded, trigger progressive structural failure. Damage initiation marks the end of a material’s purely elastic or plastic behaviour. It represents the onset of macroscopic damage rather than ultimate fracture. In advanced numerical modelling, engineers track this transition using specialized computational frameworks.
Damage initiation criterion – It defines the exact point at which a material begins to degrade or lose stiffness under applied mechanical or thermal loads. Once this threshold (such as a critical stress or strain limit) is exceeded, the material transitions from its undamaged state into progressive damage and eventual failure. In finite element analysis (FEA), this concept dictates how software predicts structural failures, such as ductile metal yielding or composite delamination. It is the trigger which initiates the damage model.
Damage inspection – It is the systematic process of identifying, measuring, and evaluating flaws, degradation, or structural faults. It determines the location, extent, and cause of damage to assess structural integrity before repair, using visual checks, or non-destructive testing (NDT) methods like ultrasonic and radiographic testing.
Damage-limiting operations – These refer to designed strategies, control systems, and protective measures meant to contain, isolate, or prevent catastrophic failure if an anomaly, breach, or extreme stress occurs. The goal is to keep the system functioning safely or degrade it in a highly controlled manner.
Damage location – It is also called damage localization. It is the process of identifying the exact physical site or region where structural, material, or mechanical degradation has occurred. It is a critical, intermediate step in structural health monitoring (SHM) aimed at assessing integrity and planning maintenance.
Damage map characteristics – Key damage map characteristics are variables, mechanisms, and life estimation.
Damage maps – These are also called deformation or fracture mechanism maps. These are graphical diagrams which show how a metal behaves under different conditions of stress, strain, and temperature. They visually predict the dominant modes of structural failure, such as yielding, fatigue, or creep.
Damage map validation – It is the process of confirming that a theoretical or computational model accurately predicts the location, severity, and morphology of material degradation, such as voids, fatigue micro-cracks, or plastic deformation.
Damage mechanics – It is the framework which models the progressive degradation of materials prior to macroscopic cracking. It uses mathematical state variables (like a damage parameter, ‘D’) to quantify how micro-defects, such as voids and microcracks, reduce a material’s stiffness, load-bearing capacity, and remaining life.
Damage mechanics approach – It is a framework used to predict material degradation, crack initiation, and failure under mechanical or environmental loads without needing to model complex micro-scale defects. It typically quantifies deterioration using a scalar or tensor damage variable (D) ranging from 0 (undamaged) to 1 (complete failure).
Damage mode – It describes the specific physical mechanism or geometric pattern by which a material or structure degrades under applied loads. It represents how micro-defects (e.g., micro-cracks, voids) initiate and propagate, ultimately reducing stiffness, load-bearing capacity, or leading to structural failure.
Damage model – It is a framework within continuum mechanics which characterizes the degradation of material properties through a damage parameter, accounting for factors like stiffness degradation and void propagation, which ultimately reduces the load-bearing capacity of a sample.
Damage morphology – It is the study of the physical shape, size, and distribution of micro-structural defects (like voids, cracks, or delamination) which degrade a material’s structural integrity. It focuses on how damage physically appears and evolves under thermomechanical stress.
Damage onset – It is the exact point when a material transitions from purely elastic deformation to permanent structural degradation, such as micro-cracking, void nucleation, or yielding. It marks the threshold where stress levels trigger irreversible microstructural changes which degrade stiffness and load-bearing capacity. This threshold is defined through specific, quantifiable criteria depending on the material and application.
Damage parameters – These are quantitative variables used in continuum damage mechanics to define the internal degradation (micro-cracks and micro-voids) of a metal under stress. They predict how and when a material’s load-bearing capacity drops to zero, leading to structural failure or fracture.
Damage potential – It is the estimated likelihood and severity of harm, ranging from functional degradation to structural collapse, which a system, material, or environment experiences under specific loads or hazards. It is calculated using damage thresholds, stress-strain states, and risk metrics.
Damage process – It is the progressive, irreversible degradation of a material or component’s physical and mechanical properties over time. It spans from initial microstructural defects to final structural failure, driven by mechanical, thermal, metallurgical, or environmental forces. The process normally breaks down into distinct phases and frameworks, formally addressed in continuum damage mechanics (CDM).
Damage propagation – It is the growth of damage within a material which occurs when the current stress state exceeds a defined damage threshold, leading to further deterioration based on the material’s loading history and stress conditions.
Damage risk – It is the potential for system failure or economic loss, calculated as the product of the probability of an unwanted event (hazard) and the severity of its consequences (vulnerability and exposure). It translates abstract threats into measurable costs and safety metrics. Damage risk analysis uses the foundational equation to quantify this metric which is ‘Risk = Probability of hazard × Severity of consequences.
Damage scenario – It defines specific events, conditions, or threats which cause physical, operational, or systemic harm to a structure, material, or system. It establishes baseline criteria for damage initiation and tracks how that damage degrades the system’s performance over time.
Damage surface – It is the conceptual boundary in stress space which defines when a material begins to transition from elastic behaviour into progressive structural degradation (such as micro-cracking or void formation). It operates in continuum mechanics similarly to how a yield surface dictates the onset of plastic (permanent) deformation.
Damage stability – It is the ability of a ship to maintain its stability and limit flooding in the event of damage, supported by damage control plans which include information on watertight subdivision, stability limiting values, and calculations for managing flooding and restoring stability.
Damage tensor – It is a mathematical construct within continuum damage mechanics used to quantify the degradation of material properties (like stiffness) because of the micro-cracks and voids. It maps the reduction of a material’s load-bearing area and relates the actual stress to the undamaged ‘effective’ stress.
Damage threshold – It is the minimum level of stress, energy, or exposure (such as force, temperature, or radiation) which a material, component, or system can endure before permanent, irreversible physical or functional degradation occurs.
Damage to buildings – It is the structural and non-structural harm which occurs as a result of strong ground shaking during earthquakes, which can lead to severe injuries, fatalities, and substantial repair costs. This damage can affect both poorly constructed structures and those designed with seismic resistance, frequently exacerbated by secondary hazards such as fires or geological phenomena like liquefaction.
Damage tolerance – It is a design measure of crack growth rate. Cracks in damage-tolerant designed structures are not permitted to grow to critical size during expected service life. It is also the ability of a part component to resist failure because of the presence of flaws, cracks, or other damage for a specified period of usage. The damage tolerance approach is used extensively in the several industries.
Damage tolerance analysis – It is the process of assessing a structure’s ability to sustain anticipated loads in the presence of defects, such as fatigue cracks or corrosion, until the damage is detected and repaired. It utilizes fracture mechanics to evaluate the residual strength and life of damaged structural components.
Damage tolerance assessment – It is an evaluation used to determine how long a structure or component can safely operate with pre-existing flaws or damage. It ensures that structural defects (like cracks, corrosion, or accidental impacts) do not lead to catastrophic failure before they are detected and repaired.
Damage tolerant approach – It is a design philosophy which assumes flaws or cracks are inherently present in any structure from the beginning or forms over time. It ensures the structure retains enough residual strength to operate safely until the damage is detected and repaired.
Damage-tolerant design – It is a philosophy assuming that flaws exist in any structure from the start or develop during service. It ensures a component retains enough residual strength safely to allow time for the damage to be detected through scheduled inspections and repaired. The approach is heavily reliant on principles of fracture mechanics to predict how long it takes for a pre-existing crack to grow to a critical size. The goal is to establish a maintenance schedule which spots and fixes the damage long before it risks causing structural failure.
Damage variables – These are parameters used in continuum damage mechanics to quantify the structural degradation of a material. They represent the nucleation and growth of micro-voids and micro-cracks. The most common scalar damage variable, ‘D’, ranges from 0 (a pristine, undamaged material) to 1 (complete failure or separation).
Damaging effect – It refers to a progressive physical process, such as fatigue, corrosion, or wear, which degrades a material, component, or system away from its initial state. It adversely affects current or future performance, reducing operational efficiency or structural integrity. These effects typically involve the nucleation of micro-cracks, void growth, or chemical deterioration caused by applied loads and environmental stressors. To quantify how a damaging effect impacts a material’s load-bearing capacity and stiffness, engineers rely on mathematical frameworks defined by continuum damage mechanics.
Damascene process – It is a semi-conductor fabrication technique used to create copper metal interconnects in integrated circuits. Instead of etching metal, it etches trenches into a dielectric insulator, fills the trenches with copper, and polishes away the excess using chemical mechanical planarization (CMP). The engineering sequence for the damascene process is broken down into two main methodologies namely single Damascene and dual Damascene.
Dam design – It is the multi-disciplinary engineering process of creating a safe and functional barrier across flowing water to impound a reservoir. It involves calculating structural integrity to withstand immense water pressure, planning for extreme floods, and selecting optimal materials based on local geological and hydrological conditions.
Dam engineering – It is a specialized discipline focused on the planning, design, construction, and maintenance of dams. It needs balancing structural integrity and hydraulic safety against environmental and geological risk factors to impound water for human use, hydroelectricity, and flood control.
Damkohler number – It is a dimensionless value which compares the rate of a chemical reaction to the rate of physical transport phenomena (like fluid flow, advection, or diffusion). Mathematically, it is defined as the ratio of the characteristic transport timescale to the characteristic reaction timescale, ‘Da = Transport timescale/Reaction timescale = Ttransport/Treaction.
Damped mode – It refers to the dynamic behaviour of a vibrating system where resistive forces (like friction or air resistance) dissipate energy, causing the oscillation’s amplitude to decay over time. Instead of vibrating indefinitely, the system gradually returns to a state of equilibrium.
Damped motion – It is a type of oscillatory motion in which the amplitude of oscillation gradually decreases because of the presence of a frictional force, which is frequently proportional to the object’s velocity. This phenomenon can manifest in different forms, including underdamped, overdamped, and critically damped motion, depending on the strength of the frictional force relative to the restoring force.
Damped natural frequency – It is the actual rate at which an underdamped physical system oscillates after an initial disturbance. Unlike the undamped natural frequency, it accounts for energy dissipation (like friction), causing the oscillations to gradually decay in amplitude. Damped natural frequency is the frequency of a damped system, which is lower than the undamped natural frequency.
Damped system – It is a mechanical or electrical set-up which loses energy over time, causing any oscillations to gradually decrease in amplitude. Energy is dissipated as heat through friction, viscous drag, or electrical resistance, preventing perpetual motion.
Damped vibrations – These are periodic vibrations with a continuously diminishing amplitude in the presence of a resistive force. The frictional forces (or resistive forces) act in the direction opposite to vibration.
Damper – It is a mechanical device in a duct or chimney which regulates the gas flow. Damper (like a shock absorber or a dashpot) absorbs unwanted energy to prevent structures from violently oscillating or failing.
Damper force – It is a resistive, velocity-dependent force which opposes the motion of a mechanical system, converting kinetic energy into heat. It is mathematically expressed in a basic linear system as ‘Fd = -cx1’, where ‘Fd’ is the force, ‘c’ is the damping coefficient, and ‘x1’ is the velocity.
Damper mass – It refers to the specific physical weight utilized in a ‘tuned mass damper’ (TMD) system. Suspended by springs and dampers (like dashpots), it oscillates out of phase with a main structure (e.g., a high-rise or bridge) to absorb and dissipate kinetic energy.
Damper system – It is a mechanism designed to dissipate kinetic energy, hence suppressing unwanted vibrations, regulating fluid or airflow, or stabilizing structures. By converting movement into thermal energy or restricting flow, these systems prevent structural failure, mechanical wear, and unsafe oscillations
Damping – It is the loss in energy, as dissipated heat, which results when a material or material system is subjected to an oscillatory load or displacement. Damping is the result of frictional forces working in that system.
Damping capacity – It is the ability of a material to absorb vibration (cyclical stresses) by internal friction, converting the mechanical energy into heat. Damping capacity is a material’s intrinsic ability to absorb and dissipate vibrational or elastic strain energy, typically by converting it into heat through internal friction. It is a critical mechanical property used in engineering to minimize noise, manage resonant vibrations, and prevent structural fatigue.
Damping coefficient – It is a parameter which defines how quickly a system dissipates its energy and returns to rest after being disturbed. It measures the resistance, such as friction or air resistance, which opposes motion, dictating whether a system vibrates, overshoots, or slowly glides back into equilibrium.
Damping component – It is a force which opposes motion in a mechanical system, which can be characterized as either linear, with a constant damping coefficient, or non-linear, where the damping coefficient varies based on factors such as internal geometry and flow conditions. Non-linear damping can affect considerably system’s resonant frequency and improve vibration control in specific frequency ranges.
Damping decrease – It refers to the reduction of a system’s energy-absorbing or vibration-restricting capability over time. It signifies that a mechanism is losing its resistive force, such as internal friction or drag, which causes oscillations (like a swinging pendulum or vibrating machine part) to decay more slowly or persist for a longer period. This concept frequently surfaces in the context of the logarithmic decrement (a key engineering metric used to calculate structural damping).
Damping effect – It is the gradual reduction of oscillations or vibrations in a physical system through energy dissipation. The ‘damping component’ (or damper) is the physical hardware, like an automobile shock absorber or a structural tuned mass damper, which converts kinetic energy into heat, preventing destructive resonance.
Damping force – It is a resistive force which opposes the motion of an oscillating or vibrating body, causing its amplitude to decrease over time. It extracts kinetic or potential energy from the system, normally by converting it into heat through friction, air resistance, or fluid viscosity. Viscous damping is typically modelled as being directly proportional to the velocity of the moving object, acting in the opposite direction.
Damping function – It is a mathematical or physical mechanism which reduces or prevents oscillations in a dynamic system by dissipating energy. It describes how the amplitude of a wave or vibrating motion decays over time, typically expressed as a function of velocity, displacement, or time.
Damping loss factor – It is a metric which quantifies how quickly a vibrating system or material dissipates mechanical energy into heat or acoustic radiation. Mathematically, it is defined as the ratio of energy dissipated per radian of oscillation to the peak potential energy stored during that cycle.
Damping matrix – It is a square and symmetric mathematical matrix used in structural and mechanical dynamics. It models the forces that dissipate energy in a vibrating system, linking structural velocities to resisting forces.
Damping parameter – It is a value which quantifies how quickly a vibrating or oscillating system loses energy and comes to rest. It characterizes how forces, such as friction or air resistance, oppose motion, ultimately determining whether a system returns to equilibrium smoothly or oscillates with decreasing amplitude.
Damping property – It is the intrinsic capacity of a material or system to dissipate kinetic energy (normally from vibrations or oscillations) and convert it into thermal energy. It governs how quickly a swinging or vibrating object comes to a resting state, stabilizing the structure or system.
Damping ratio – It is a parameter which indicates how rapidly oscillations in a system die out, if ever.
Damping resistor – It is an electrical component specifically designed to absorb transient energy and suppress unwanted oscillations, voltage spikes, or ‘ringing’ in a circuit. By converting excess energy into heat, it stabilizes the system and prevents damage to sensitive equipment during switching or fault events.
Damping system – It consists of mechanisms or components crafted to minimize vibrations and oscillations in the conveyor system, prompting routine checks to ensure continued effectiveness.
Damping term – It refers to the factor which influences the dissipation of structural vibration energy, playing an important role in controlling the amplitude and duration of vibrations in structures such as bridges. It is necessary for reducing resonance phenomena and improving stability and safety under various conditions.
Damping treatment – It is a mechanical or material modification engineered to reduce vibrations, noise, or shock. By adding visco-elastic or tuned mass materials to a structure, it extracts kinetic energy and dissipates it as heat, which minimizes structural resonance and prevents extreme oscillations.
Damp proofing – In construction, it is a type of moisture control applied to building walls and floors to prevent moisture from passing into the interior spaces. Dampness problems are among the most frequent problems encountered in building constructions.
Danger – It is a state or condition in which personal injury and / or asset damage is reasonably foreseeable. It is the presence of a hazard.
Dangerous cargo – It is also called hazardous materials or hazmat. It refers to goods which pose a risk to health, safety, property, or the environment during transport. Because of their intrinsic properties, such as flammability, toxicity, or reactivity, these materials need specialized packaging, strict documentation, and specific safety protocols. The transport of dangerous goods is strictly regulated internationally by organizations.
Dangerous occurrence – It is a near miss with serious injury potential.
Dangling – It consists of disconnect of an activity before the completion of all activities in a network diagram.
Dangling bond density – It refers to the concentration of unsatisfied or broken chemical bonds at the surface, interface, or within the structural defects of a material (typically covalent solids like semi-conductors). It is normally expressed as the number of dangling bonds per unit volume or per unit area.
Dangling bonds – These bonds are unsatisfied valences on immobilized atoms which possess unpaired electrons, rendering them highly reactive. These bonds are substantial in nano-particles because of their high surface-to-volume ratio and influence crystal growth and optical properties.
Dang Van criterion – It is a widely used multiaxial high-cycle fatigue criterion. It is used to predict the infinite fatigue life of metal components subjected to complex, combined, and non-proportional cyclic stresses (such as bending, torsion, and rolling contact). The criterion is based on two fundamental metallurgical and micro-mechanical principles namely the mesoscopic scale (grain level), and elastic shake-down.
Dang Van diagram – It is a graphical tool used to evaluate high-cycle multiaxial fatigue. It helps predict whether a metal component is going to experience crack initiation when subjected to complex, changing stresses (like in rotating shafts or rolling bearings) by analyzing microscopic shear and hydrostatic stresses. The diagram is plotted on a 2D coordinate system designed to separate macroscopic loads from microscopic grain-level behaviours.
Danieli universal endless (DUE) concept – It is a patented thin-slab casting and rolling method which allows a single steel plant to seamlessly switch between full endless, semi-endless, and traditional coil-to-coil rolling modes. It optimizes by utilizing continuous thermo-mechanical processing to refine grain structures and improve product uniformity.
Daniell cell – It is an electro-chemical cell which converts chemical energy into electrical energy using spontaneous redox reactions. It consists of a zinc electrode submerged in zinc sulphate and a copper electrode in copper sulphate, typically yielding around 1.1 volts of electricity. The cell is split into two half-cells, allowing electrons to move through an external wire to generate current.
Danner process – It is a continuous method used for producing glass tubing and rods. In this process, molten glass is drawn from a furnace as a ribbon onto a rotating refractory cylinder (Danner pipe). The glass ribbon is then wrapped around the cylinder, forming a smooth layer that is blown into tubing by compressed air. The diameter of the tubing is determined by the pressure of the air, the temperature of the glass, and the speed of drawing.
Darcy equation – It is a mathematical relationship used in the quantitative characterization of permeability, linking fluid currents to pressure gradients through permeability coefficients and fluid viscosities. It is a specific type of Onsager equation fundamental to studies of permeability in different systems.
Darcy friction factor – It is also called Darcy–Weisbach friction factor. It is a dimensionless coefficient used in the Darcy–Weisbach equation to calculate head loss (pressure drop) because of the friction in pipe and open-channel flows. It is precisely four times larger than the Fanning friction factor.
Darcy flow – It is the fluid flow which assumes laminar conditions within a formation, typically described by Darcy’s law, which contrasts with non-Darcy flow which shows turbulent conditions, especially near the well-bore.
Darcy number – It is a dimensionless parameter representing the relative ratio of a porous medium’s permeability to its physical cross-sectional area (normally the square of a characteristic length). It is used to quantify fluid flow and heat transfer through porous materials.
Darcy’s law – It is a fundamental equation in hydro-geology and fluid mechanics which describes the rate at which fluid flows through a porous medium. It states that fluid discharge is directly proportional to the hydraulic gradient and the cross-sectional area of the medium.
Darcy velocity – It is also called Darcy flux / specific discharge. It is the volumetric flow rate of fluid per unit of total cross-sectional area in a porous medium. Represented by ‘q’, it is calculated through Darcy’s law, ‘q = -K dh/dL. Although expressed in units of velocity, it is an apparent bulk flux rather than the physical speed of the fluid.
Darcy-Weisbach equation – It is a fundamental fluid mechanics formula which calculates the head loss (or pressure drop) because of the friction when a fluid flows through a pipe.
Darcy-Weisbach friction factor – It is a coefficient which quantifies the friction loss because of the flow in a pipe, and it depends on the Reynolds number and relative roughness of the pipe surface.
Dark current noise – It is the intrinsic noise in photo-detectors caused by the number of induced electrons generated from thermal agitation, which increases with temperature and results in an offset in pixel values, leading to noise and reduced dynamic range.
Dark-field illumination – It is the illumination of an object such that it appears bright and the surrounding field dark. This results from illuminating the object with rays of sufficient obliquity so that none can enter the objective directly. In electron microscopy, the image is formed using only electrons scattered by the object.
Darlington pair – It is an electronic circuit configuration consisting of two bipolar junction transistors (BJTs) connected in cascade. The emitter of the first transistor feeds into the base of the second, compounding their current gains and allowing a very small input current to drive large loads.
Darrieus–Landau instability – It refers to an instability of chemical fronts propagating into a denser medium. It is a key instrinsic flame instability which occurs in premixed flames, caused by density variations because of the thermal expansion of the gas produced by the combustion process. In simple terms, stability inquires whether a steadily propagating plane sheet with a discontinuous jump in density is stable or not. The analysis behind the Darrieus–Landau instability considers a planar, pre-mixed flame front subjected to very small perturbations.
Dashboard – It is a user interface which displays key information in an easy-to-read format. It is designed for monitoring and overview, typically showing metrics and data.
Data – It consists of a collection of facts, observations, or measurements used for analysis and decision-making. Data can be numerical, such as counts or measurements, or categorical, such as labels or classifications. Data serves as the starting point for analysis. It is what people examine, manipulate, and interpret to draw conclusions or make predictions about a particular phenomenon or population. Data forms the bedrock of analysis and decision-making. In statistics analysis, data consist of numbers, letters, or special characters representing measurements of the properties of one’s analytic units, or cases, in a study. Data are the raw material of statistics.
Data access – It refers to the authorized ability of users or systems to retrieve, modify, copy, or move digital data stored in an IT (information technology) system. It involves the specific permissions, security protocols, and technologies, like application programming interfaces (APIs) or query languages, which dictate who can interact with information and how.
Data accuracy – It is the degree to which data correctly and precisely represents the true, real-world state, value, or event it is intended to describe. It is a foundational metric of data quality used to ensure analytical and operational models function correctly without faulty inputs.
Data aggregation – It is the process of collecting raw data from multiple disparate sources and compiling, standardizing, and summarizing it into a unified, consolidated dataset. It translates granular, low-level data into meaningful metrics for analysis.
Data analysis – It can be defined as a data science used to break data into individual components for inspection and integrating these components to create knowledge. It is described as a set of concepts and methods intended for presentation of the data in a form which improves the quality of the decision making. It is the process of collecting, modelling, and analyzing data using different logical methods and techniques. Informally, there is a five-step ‘value-chain’ approach for extracting useful value from the data using data analysis. These steps are (i) organizational needs identification of data, (ii) collection of the data, (iii) data exploring and cleaning, (iv) data analyzing, (v) interpreting the data and drawing inferences. The data interpretation helps in making a decision and measuring of the outcome for the purpose of updating the process or system with the results of the decision. Data analysis can be categorized into the six main methods namely (i) descriptive, (ii) exploratory, (iii) inferential, (iv) predictive, (v) explanatory or causal, and (v) mechanistic.
Data acquisition – It is the process of measuring an electrical or physical phenomenon, such as voltage, current, temperature, pressure, or sound with a computer or a data logging device.
Data acquisition board – It is a hardware component which measures physical phenomena (like temperature, pressure, or voltage) and converts these analog signals into digital data. This allows computers to process, analyze, and store real-world measurements using programmable software. A data acquisition (DAQ) acts as the bridge between physical environments and computing systems, relying on several key elements.
Data acquisition hardware – It is the components which collect and convert analogue signals from sensors into digital format for processing and analysis by a computer. This hardware includes elements such as multiplexer, analog-to-digital converters, and interfaces which facilitate the transfer of data to the computer system.
Data acquisition system – It refers to the combination of hardware and software tools that measure physical parameters from the real world, such as temperature, pressure, sound, motion etc. and convert the data into digital values which can be saved, analyzed, or transmitted on a computer. It is the device which is used to perform data acquisition (DAQ) measurement. It typically consists of a set of sensors or transducers, signal conditioning circuitry, and an analog-to-digital converter (ADC) which converts the analog signals from the sensors into digital values which can be processed by a computer. Data acquisition system is a system which includes measurement devices, sensors, a computer, and data acquisition software. A data acquisition system is used for acquiring, storing, visualizing, and processing data. This involves collecting the information needed to understand electrical or physical phenomena. Data acquisition systems are used in a variety of applications, including design and development, manufacturing, and process control.
Data acquisition and control system – It collects, processes, and measures real-world physical conditions (like temperature or pressure) and translates them into digital values. It then uses this information to execute preprogrammed commands and automatically adjust parameters to optimize and regulate physical or industrial processes.
Data acquisition board – It is a hardware component or printed circuit board (PCB) which acts as an interface between the physical world and a computer. It collects real-world analog signals (such as temperature, pressure, or sound) from sensors, converts them into digital data, and sends them to a computer for analysis and monitoring.
Data acquisition card – It is a hardware device installed in or connected to a computer to measure, collect, and digitize real-world physical phenomena, such as temperature, pressure, voltage, or sound. It translates these analog signals into digital data which computers can process, store, and analyze. A data acquisition (DAQ) card acts as the bridge between the physical world and computer processing software.
Data acquisition device – It is hardware which captures real-world physical phenomena, such as temperature, pressure, or sound, and converts them into digital signals. It acts as the critical bridge between physical sensors and a computer, enabling analysis, storage, and monitoring.
Data acquisition hardware – It comprises the physical components which collect real-world physical measurements (such as temperature, pressure, or sound) from sensors and convert them into digital signals. This allows computers and software to process, analyze, and store the data.
Data acquisition process – It is the systematic process of gathering, measuring, and converting physical phenomena (like temperature, pressure, or voltage) from the real world into digital formats which computers can analyze and store. It involves sensors, signal conditioning, and analog-to-digital converters to translate these signals.
Data acquisition system – It is a set-up which measures real-world physical phenomena, like temperature, pressure, or vibration, and converts them into digital data. Computers process, analyze, and store this digital information. A standard data acquisition system consists of three core elements namely sensors / transducers, signal conditioning, and analog-to-digital converter (ADC).
Data aggregation – It consolidates readings or signals from hundreds of individual sensors or meters into a single, manageable stream.
Data analysis tools – These are software programmes and platforms designed to collect, clean, manipulate, analyze, and visualize vast quantities of raw data. They help individuals and organizations uncover hidden patterns, spot trends, and extract actionable insights to drive smarter organizational decisions.
Data asset – It is a digital entity of data which is refined, governed, and recognized as having continuous value to an organization. In data engineering, a data asset refers to a specific, structured, or semi-structured data entity, e.g., a curated database table, data stream, or ML (machine learning) feature, which is built, maintained, and delivered to downstream users. Data engineering treats data assets as core organizational inventory, emphasizing rigorous processing and continuous availability.
Data associativity – It is the ability of a computer-aided engineering system to share design information among a variety of computer-based applications (such as design, drafting, and numerical-controlled machining) without each application having to translate or transfer the data. Associativity also needs that applications can recognize when geometry or other information has been changed so that the application can adjust its own data to these changes.
Database – A database is an electronically stored, systematic collection of data. It can contain any type of data, including words, numbers, images, videos, and files. It is a collection of specific information, such as alloy compositions or mechanical properties. Several databases are accessible through on-line connections or with a CD-ROM (compact disc read-only memory).
Database algorithm – It is a finite, unambiguous set of rules or instructions engineered to manipulate, store, index, and retrieve data from a database system efficiently. In software engineering, database algorithms bridge theoretical data management and physical system architecture. They ensure optimal memory allocation, fast query processing, and data consistency under heavy work-loads.
Database management system – It is a software to store, manage, retrieve, and edit data.
Database result – It is the structured output returned by a query or operation. In software engineering, defining it involves establishing the data types, metadata, and status (e.g., success / failure), ensuring the retrieved data exactly matches application requirements, maintains referential integrity, and meets performance SLAs (service-level agreements).
Database selection – It is the systematic process of evaluating and choosing the optimal database technology for a system based on specific technical and organizational requirements. The goal is to maximize performance, scalability, and data integrity while minimizing operational complexity and costs.
Data binning – It is a data pre-processing technique used to group continuous, numerical values into smaller, discrete intervals or categories called bins. It is mainly used to simplify datasets, reduce the impact of minor observation errors, and make large datasets easier to analyze and visualize. Data binning transforms raw, continuous data to make it more manageable.
Data bins – These bins refer to categorized groups of related values created by binning, which reduces the number of distinct values of a data attribute for analysis in data mining algorithms. This process improves the efficiency of model building by organizing data into discrete sets, such as equi-width or quantile bins.
Data breach – It is a confirmed security incident where sensitive, confidential, or protected data is accessed, copied, transmitted, or stolen by unauthorized individuals. It specifically refers to the compromise of the data itself, differentiating it from a general network attack.
Data byte – It is a unit of measurement which contains eight bits, or a series of eight zeros and ones. A byte can be represented as a character such as a number, letter or typographic symbol.
Data cleaning – It is the process of identifying and correcting or removing errors, duplicates, and inconsistencies within a data set. Its main goal is to ensure the data is accurate, complete, and reliable for analysis, reporting, or training machine learning models.
Data clustering technique – It is an unsupervised machine learning technique which groups similar unlabeled data points together. It partitions datasets based on inherent patterns, ensuring that items within the same group share high similarity while differing considerably from items in other groups.
Data collection unit – It is a specific, natural, or human-defined entity (such as a person, organization, or geographic boundary) from which statistical or analytical information is gathered. It can also refer to physical hardware, such as an electronic device or sensor, used to automatically capture and store data.
Datacolour – It defines as the precise, software-driven process of formulating, measuring, and matching colour across materials. It involves using spectro-photometers and AI (artificial intelligence) powered software to calculate exact colourant recipes, ensuring standardized colour harmony across supply chains.
Data communication equipment – It is also known as data circuit-terminating equipment. It refers to devices which sit between a data source / destination and a communication network. They convert and transmit signals for the network. Common examples include modems, routers, and network interface cards (NICs).
Data component – It is an isolated, reusable software module or architectural layer designed to manage, store, or process specific units of data. It translates raw data facts into functional information, serving as the foundation for broader systems like database architectures or web applications.
Data compression – It is a technique which allows information to be transmitted more compactly than originally expressed, for example, codes.
Data concentrator – It is a networking and telecommunications device which acts as a central hub to collect, process, and temporarily store data from multiple low-speed sources before transmitting it to a central destination. It bridges the gap between field devices and cloud or utility servers.
Data converter – It is an electronic circuit which translates information between analog and digital formats. It bridges the physical world, where signals like temperature and sound are continuous, with digital systems (like computers and micro-controllers) which process data in discrete binary values.
Data corpus – It is a large, structured collection of authentic text, speech, or other language data used as a foundation for research, statistical analysis, or training. In machine learning, it serves as the foundational data set.
Data delivery – It is the secure, customizable process of transporting prepared data from its source (like a database) to end-users, applications, or data ware-houses. It acts as a digital courier, orchestrating the movement, formatting, and access controls so the right information is reliably available.
Data design – It is the process of creating a blue-print for how data is structured, stored, and accessed within a system. It focuses on defining data types, relationships, and storage mechanisms to ensure information remains accurate, secure, and easy to use.
Data diagnostics – It is a form of analysis which examines historical datasets to uncover the root causes of specific events, behaviours, or outcomes. It goes beyond merely describing ‘what’ happened by answering ‘why’ it happened, using techniques like drill-down, data mining, correlation analysis, and statistical modeling.
Data direction register – It is a hardware memory location in micro-controllers which configures the direction of data flow for input / output (I/O) pins. It tells the micro-controller whether a specific pin is to act as an input to read sensor data or an output to drive devices like LEDs (light-emitting diodes).
Data-driven science – It is a methodology which relies on the analysis of massive data sets to discover patterns, test hypotheses, and drive discovery. Frequently called the ‘fourth paradigm’ of science, it integrates machine learning and statistical modelling to complement traditional theoretical and experimental approaches.
Data encryption standard – It is a method which uses intricate procedures to encrypt data, utilizing a 56-bit key and dividing messages into 64-bit blocks for encryption. It involves a series of transpositions, substitutions, exclusive OR operations, and other processes to produce 64 bits of encrypted data.
Data element – It is the smallest, indivisible unit of information which conveys a specific, unambiguous meaning. It serves as a building block in data models, defining a discrete attribute (e.g., voltage, temperature, and part number etc.) by its name, technical data type, and representation. Understanding data elements needs looking at both their conceptual role and software / system application.
Data element definition – It refers to a precise and unambiguous statement which describes what a data element is, without incorporating definitions of other data concepts or elements. It is to be concise, avoid circular reasoning, and not include procedural information.
Data engineering – It is the practice of designing, building, and maintaining the infrastructure which collects, stores, and transforms raw data. By creating reliable data pipelines, it makes fragmented information clean, structured, and ready for analysis and AI (artificial intelligence).
Data flow – It refers to the path and movement of data through an information system, from its source to its destination. It encompasses how data is collected, transformed, routed, and stored within a system architecture.
Data flow control – It is the process of managing the rate and direction of data transmission between devices in a network or components in a system. Its main purpose is to ensure a fast sender does not overwhelm a slower receiver, which prevents buffer overflow, minimizes data loss, and optimizes overall system performance.
Data flow diagram – It is a graphical model which maps out the flow of information through an information system. It visually shows how data enters, is processed, stored, and eventually outputted by a system, without detailing the timing or sequence of processes.
Data flow graph – It is a computational model which visualizes data dependencies and movement within a system. It uses nodes (or vertices) to represent operations or transformations, and directed edges (arcs) to represent the data flowing between them, making it fundamental for parallel computing and machine learning.
Datagram – It is a self-contained, independent data unit sent over a packet-switched network. It contains all necessary routing information, such as source and destination addresses, in its header, needing no prior connection set-up or hand-shake between the sender and receiver.
Data highway – It is a single-cable link which provides communication between control stations which are physically separated.
Data integration – It is the process of combining data from multiple source systems to provide a complete, accurate, and up-to-date dataset and unified sets of information for both operational and analytical uses.
Data integrity – It is the maintenance, assurance, and preservation of data’s accuracy, consistency, and reliability across its entire life-cycle. It ensures that information remains uncorrupted, valid, and fully trustworthy from the moment it is created, processed, and stored to its final retrieval. Data integrity is classified into two main categories, each with distinct standards. These categories are physical integrity, and logical integrity.
Data item -It is the smallest unit of meaningful information within a data-set or data structure. It represents a single, distinct piece of data or a specific value associated with the property of an entity (e.g., a single name, a date, or an integer).
Data link – It is a connection between two or more devices used to transmit and receive digital information. In networking, it refers to the data link layer (Layer 2 of the open system inter-connection, OSI model), which ensures data is transferred reliably and without errors between directly connected nodes on a local network.
Data linking – It connects information across different systems. Instead of duplicating or synchronizing files, engineering teams link to the single source of truth. This ensures real-time visibility, eliminates obsolete data, and maintains clear audit trails.
Data link layer – It is the layer 2 of the OSI (open system inter-connection) model. It is responsible for node-to-node data transfer across a single local network. It groups raw bits into structured ‘frames’, manages physical MAC (media access control) addresses, and ensures error-free transmission.
Data loss – It is the permanent destruction, corruption, or unavailability of digital information. It occurs when important data becomes unreadable or irretrievable because of the hardware failure, software bugs, or human error, rather than being stolen or exposed (which is a data breach).
Data loss prevention – It refers to a set of strategies, software, and processes designed to detect and block the unauthorized access, transfer, or destruction of sensitive data. It ensures critical information, such as intellectual property (IP) and system metrics, is protected from accidental exposure or malicious exfiltration.
Data memory – It refers to the primary memory or RAM (random access memory) in a computer or micro-controller. It is a volatile, read-write storage area used to temporarily hold variable data, interim calculation results, and active programme states while the system is actively executing tasks. Understanding data memory involves exploring how it operates, its hardware characteristics, and how it differs from other memory types.
Data mining – It is the process of extracting hidden, actionable patterns, correlations, and anomalies from large, complex datasets using statistics and machine learning. It transforms raw, sensor-generated, or historical data into predictive models and design insights.
Data mining techniques – These are computational methods used to discover hidden patterns, correlations, and anomalies within massive data sets. By combining machine learning, artificial intelligence, and statistics, these techniques transform raw data into actionable intelligence for decision-making.
Data model – It is a visual or structural blueprint which organizes how data is defined, stored, and connected within a system. It acts as a universal dictionary, mapping out real-world entities (like customers or products) and establishing the rules and relationships that govern them.
Data modulation – It is the process of superimposing digital or analog information onto a higher-frequency carrier signal for transmission. It alters specific properties of the carrier wave, such as its amplitude, frequency, or phase, allowing data to travel efficiently across media like radio waves, fibre optics, or telephone lines.
Data modulator – It is an electronic circuit or device which encodes information (binary data or analog signals) into a higher-frequency carrier signal for transmission. It super-imposes the information signal onto the carrier by dynamically varying properties like its amplitude, frequency, or phase to enable efficient long-distance transmission over cables or radio waves.
Data networks – It is a digital telecommunications infrastructure which connects computers, servers, and devices to share information and resources. It breaks data into packets and transmits them through cables or wireless signals to be reassembled at their destination.
Data organization – It is the process of structuring, categorizing, and managing raw data so it becomes easily accessible, accurate, and ready for analysis. It simplifies complex datasets, reduces errors, and allows users to quickly extract meaningful insights.
Data, outlier – Outlier data refers to data points which deviate considerably from the majority of a data set, which can arise from objective factors, such as changes in conditions, or subjective factors, such as human influence. The detection and analysis of outlier data are important for assessing data quality, as these points can contain valuable information despite sometimes being perceived as noise.
Data path – It is the hardware foundation of a central processing unit (CPU) which performs all actual data processing. It is the physical ‘highway’ where instructions are executed and data is manipulated, consisting of the ‘arithmetic logic unit’ (ALU), registers, and internal buses. The data path does not make decisions on its own. It operates strictly under the direction of the control unit, which issues electrical signals to orchestrate the flow of data.
Data plot – It is also known as a chart or graph. It is a visual representation of data, typically used to show relationships between variables, trends, or distributions. It is a way to present information in a way which is easier for humans to understand and interpret than a long list of numbers.
Data preparation – It is the process of gathering, cleaning, transforming, and organizing raw data so it can be accurately analyzed or used to train machine learning models. It resolves inconsistencies, removes errors, and structures disorganized data, ensuring your business intelligence and AI (artificial intelligence) insights are reliable.
Data preprocessing – It is the process of cleaning, transforming, and organizing raw data into a structured format so it can be effectively used for machine learning models and data analysis. It ensures data is accurate, consistent, and free of noise, ultimately preventing skewed results and improving overall predictive performance.
Data processing procedure – It is the systematic sequence of steps used to collect, clean, convert, and analyze raw data, transforming it into meaningful, actionable information. It acts as the core engine turning unstructured inputs (like numbers, text, or sensor readings) into valuable intelligence for decision-making.
Data profile – It is a summary report which evaluates the condition, structure, and quality of a data set. It provides important statistics, such as data types, minimum values / maximum values, uniqueness, and missing values, to help analysts and organizations understand whether the data is accurate, complete, and usable for analytics.
Data profiling – It is the process of examining, analyzing, and summarizing raw datasets to assess their quality, structure, and content. It provides a high-level overview of data characteristics, such as accuracy, consistency, and completeness, ensuring it is reliable for business intelligence and analytics before being put to use.
Data pulse – It normally refers to a transient, time-series, or event-driven data set which provides a quick, real-time snapshot of system health, quality, or user activity.
Data qubit – It is a distinct qubit within a quantum circuit or register used to directly store and manipulate the main payload of information, rather than serving as an auxiliary or control qubit. In algorithms, it is the target of operations (like logic gates) driven by other control qubits.
Data rate increase – It refers to an improvement in the speed at which information is transmitted or processed, measured in bits per second (bps). It yields faster downloads, smoother streaming, and lower latency, achieved by upgrading hardware, expanding channel bandwidth, or using more efficient encoding schemes. In computing and tele-communications, a higher rate of data transfer is heavily tied to both infrastructure and signal theory.
Data reconciliation – It is the systematic process of comparing two or more datasets to identify and resolve discrepancies, ensuring that information remains consistent, accurate, and complete across different systems. It establishes a ‘single source of truth’ by tracking down missing records, duplicates, and mismatched values.
Data recording – It is the systematic process of capturing, documenting, and storing information. It ensures data integrity and traceability. Whether done manually or digitally, it is important for maintaining records in different fields.
Data register – It is a small, ultra-fast temporary storage location inside a computer’s CPU (central processing unit). It holds the actual data, operands, or intermediate results which the processor is currently working on or needs for immediate execution, considerably speeding up processing time.
Data retention – It is the practice of storing information for a specified period to comply with laws, support business needs, and manage risk. It defines exactly what data is kept, where it is stored, and how it is securely disposed of once the retention period expires. A well-structured retention strategy dictates the entire life-span of information.
Data science – It is the multi-disciplinary application of mathematics, statistics, and computer science to extract actionable insights from complex, noisy datasets. It focuses on building predictive models, optimizing physical systems, and automating processes using machine learning, artificial intelligence, and programming.
Data security – It is the practice of protecting digital information from unauthorized access, corruption, theft, or loss throughout its entire lifecycle. It encompasses the hardware, software, user devices, administrative controls, and organizational policies needed to keep valuable digital assets safe from cyber threats and human error.
Data set – It is a structured collection of related data, frequently organized and stored together for analysis or processing. It is essentially a file or other format which contains data values, typically organized in a way which is meaningful for a specific purpose. In the case of tabular data, a data set corresponds to one or more database tables, where every column of a table represents a particular variable, and each row corresponds to a given record of the data set in question. The data set lists values for each of the variables. Data sets can also consist of a collection of documents or files.
Data set basis – A base dataset is defined as a large labeled dataset used to train a classification model, allowing the model to learn from all base classes with classification loss prior to performing few-shot tasks.
Data set parameter – It is a dynamic variable used in data queries, reports, or machine learning pipelines to filter, manipulate, or restrict information. By defining parameters, users can interactively update data outputs, such as narrowing a sales database by date or region, without altering the underlying code.
Data-sheet – It is a standardized document which summarizes the technical specifications, performance metrics, and characteristics of a product, component, or material. Created by manufacturers, it provides enough detail for buyers to understand the product and for engineers to implement it into a system. In statistical process controls, data-sheet is a tool for the systematic collection of data.
Data signal – It is the physical, electronic, or electro-magnetic representation of raw data used to transmit information between devices. It converts abstract binary code (0s and 1s) or continuous data into physical wave-forms, such as voltage changes, light pulses, or radio waves, to travel across networks like Wi-Fi or Ethernet.
Data source – It is the origin of raw facts, figures, and measurements. It encompasses the instruments, systems, and repositories from which information about material properties, extraction processes, and manufacturing conditions is gathered for analysis, quality control, and predictive modeling.
Data structure – It is a specialized format designed to organize, store, manage, and process data efficiently in a computer’s memory. Data structure engineering involves analyzing the computational requirements of an application to select, modify, or design data arrangements which minimize space (memory consumption) and time (execution speed) complexities.
Data transfer – It is the process of moving digital information, such as files, documents, or media, from one location, device, or system to another. This process underpins all digital communication and occurs either across a local network or via the internet.
Data transfer rate – It is the speed at which digital data moves between two points over a network or storage medium. It is mainly measured in bits per second (bps) for networking, or bytes per second (B/s) for file storage, and indicates overall channel capacity.
Data type – It involves specifying the value space, valid operations, and memory constraints for custom data models. It ensures data integrity, prevents errors, and optimizes performance across analytics pipelines, databases, and microservices.
Data type conversion – It is also known as type casting or type coercion. It is the computer programming process of changing a value from one data type to another. This technique ensures compatibility between different data variables during calculations, data processing, and application management.
Data use – It is the active application of processed, reliable information to inform decisions, build models, or generate actionable insights. It represents the final stage of the data lifecycle, ensuring data is accurately interpreted by analysts, engineers, and machine learning models. The concept of data use is normally broken down into two main contexts namely downstream analytics usage and operational application.
Data validation – It is the process of ensuring that information conforms to predefined quality standards, rules, and constraints before it is stored, processed, or used. It acts as a main defense to confirm that data is accurate, reliable, and fit for its intended purpose. In data engineering and software engineering, it is typically used in data pipelines and input forms to prevent corrupted or anomalous data from disrupting downstream systems. In systems and hardware engineering, it refers to ensuring that design inputs stick to expected limits.
Data vault – It is an agile data modelling and architecture pattern used to build scalable, auditable, and historical enterprise data warehouses. It is specifically designed to handle data from multiple disparate sources without needing a total system redesign when source systems change. The data vault methodology stands out by separating organizational data into three core tables namely hubs, links, and satellites.
Data warehouse – It is a central repository used to collect, integrate, and store large volumes of current and historical data from multiple disparate sources. It is optimized for complex analytics, reporting, and business intelligence (BI) rather than daily transaction processing.
Datum – It is used for dimensioning. It is the reference from which dimensioning is done. It can be a point, line, or plane which are collectively known as datums. Datums have selected locations which are fixed and theoretically exact.
Datum axis – It is a theoretical, perfectly straight centre-line used in engineering and manufacturing as a reference point for measuring and tolerancing parts. It is typically derived from a physical feature, such as the centre of a cylindrical shaft, a bore, or the intersection of two datum planes. In mechanical design, understanding how a datum axis functions needs looking at its role in both design and manufacturing.
Datum feature – It is a tangible, physical characteristic of a part (such as a flat surface, hole, slot, or cylinder) identified on an engineering drawing. It is used as the starting anchor to establish a theoretical reference point, axis, or plane (the datum) from which all other dimensions and tolerances are measured.
Datum line – It has length but no width or depth, such as the intersection of two planes, an axis of rotation, a centre-line, or other reference line arbitrarily fixed on a design feature for a functional, gauging, or tooling aid.
Datum plane – It is a theoretically exact flat surface, point, or axis used as an anchor or reference for manufacturing, inspecting, or drawing. All dimensional measurements and geometric tolerances for a fabricated metal part originate from this reference frame.
Datum point – It has position but no extent, such as the centre of a sphere, the apex of a cone or pyramid, or a reference point arbitrarily fixed on a design feature for a functional, gauging, or tooling aid.
Datum plane – It has length and width but no depth. Reference planes arbitrarily assigned to a design feature, such as top, bottom, waterline, or incline, are examples of datum planes.
Datum surface – it is a theoretical, exact plane, axis, or point used as a reference for consistent measurements, manufacturing, or surveying. It acts as an anchor or starting point to apply strict tolerances, measure elevations, or calculate distances.
Daub – It refers to a specialized refractory mixture, normally a high-heat resistant blend of clay, sand, and water. It is used to coat, patch, and repair the linings of melting furnaces (like cupolas) and molten metal ladles. It also refers to a natural, sticky composite material used as a coating, plaster, or structural infill. It is most famously used in ancient, historical, and sustainable earth-building techniques like wattle and daub to create robust, weather-proof, and thermally regulating wall systems.
Daubechies wavelets – These are a family of orthogonal mathematical functions used in discrete wavelet transforms to break down complex signals or images into different frequency components. These are widely applied in data compression, signal denoising, and feature detection.
Daubing – It is filling of cracks in moulds or cores by specially prepared pastes or coatings for preventing a mechanical penetration of metal into these cracks during pouring. It is also, the final plastering or coating of the cupola or ladle after shrinkage has taken place during the drying period. Clay slurry or clay wash with different coating compounds are applied.
Davit – It is a compact, crane-like mechanical device consisting of a vertical post and a pivoting or fixed arm. It is used to suspend, raise, and lower equipment, personnel, or boats within a constrained radius. Unlike standard cranes which rotate weights across dynamic, large work zones, a davit is built for fixed-arc or localized movements. Davit arms are important access and safety tools for buildings and industrial sites.
Day – It is mainly defined as a period of 24 hours or the time it takes for the earth to complete one full rotation on its axis. It also refers to the period of daylight between sunrise and sunset, as well as a specific date.
Day-ahead demand response programme – It is an incentive-based electricity programme which compensates commercial and industrial users for voluntarily reducing their power consumption in wholesale energy markets. Participants submit curtailment bids indicating how much load they can reduce and at what price.
Day-ahead market – It is a financial and physical electricity trading platform where buyers and sellers trade power for the following day. Participants submit hourly or 15-minute bids, and a double-sided auction determines the market clearing price and delivery schedules before actual production begins. Understanding the day-ahead market involves looking at its core purpose, how its auction mechanism works, and its relationship to real-time grid balancing.
Day bin – It is a bin normally having a capacity of one day consumption. It receives bulk material from the bulk material storage and convey it for use in a process for the production of the product.
Day compressive strength – It is the measured capacity of a material, mainly concrete, to withstand pushing or compressing forces at a specific age. Examples are 7-day or 28-day strengths. It evaluates structural integrity and maturity, with the 28-day mark acting as the universal benchmark for full-design strength.
Daylight – It is the distance, in the open position, between the moving and the fixed tables or the platens of a hydraulic press. In the case of a multi-platen press, day-light is the distance between adjacent platens. Day-light provides space for removal of the moulded / formed part from the mould / die. It is far more commonly used to define the controlled capacities.
Daylight factor – It is the ratio of indoor natural light to outdoor light under an unobstructed, overcast sky, expressed as a percentage. It helps architects design well-lit spaces by assessing how much daylight reaches a specific point.
Daylight fluorescent pigments – These are vibrant colourants which absorb invisible ultra-violet (UV) radiation and shorter-wave-length visible light (like blue light) from natural sunlight, immediately re-emitting it as longer-wave-length visible light. This process makes them appear up to three times brighter and glow much more intensely than conventional colours. Unlike standard pigments which simply reflect specific wave-lengths and absorb the rest as heat, Daylight fluorescent pigments (DFPs) convert extra absorbed energy into visible light.
Daylight illuminant – It is a theoretical, standardized light source defined by the International Commission on Illumination (CIE) which mathematically describes the exact spectral power distribution of natural daylight. It provides a universal baseline for accurately measuring and comparing colours across photography, manufacturing, and design. Since the natural spectrum of the sun changes based on the weather, geographical location, and time of day, industries need consistent, bias-free standards. To ensure everyone is ‘speaking the same language’ when evaluating a colour, daylight illuminants lock in data regarding the relative energy at each visible wavelength.
Daylighting – It is the dynamic interplay of diffuse skylight, reflected light, and intense, directional sunlight which varies in intensity, direction, and spectrum over time and weather conditions. It can be utilized in design to create engaging lighting effects, known as ‘light chords’, which improve indoor environments.
Day-light limitation – It is the maximum open distance available to load, position, and unload parts, dictating the maximum height of the dies or moulded pieces.
dB bandwidth – It is frequently referred to as the 3-dB bandwidth. It is the range of frequencies over which a system passes signals effectively. It represents the specific frequency difference between the upper and lower cutoff limits where a system’s output power drops to half (-3 dB) of its maximum value.
dB compression point – It is the output level at which the output signal is compressed by 1 dB from the ideal input / output transfer function, indicating that the amplifier’s dynamic range has been reached and further increases in input will not result in increased output.
D-Bolt – It is a specialized, energy-absorbing rock bolt made of a smooth steel bar with integrated anchors along its length, designed to safely yield and absorb extreme dynamic loads during rock bursts or ground squeezing.
DC bus voltage– It is the electrical potential measured on the internal direct current (DC) power rail within electronic devices like variable frequency drives (VFDs) or servo systems. It acts as a stable intermediate buffer where rectified AC (alternating current) power is stored and filtered before being converted back into variable alternating current power to drive motors.
DC casting – It is direct chill (DC) casting and is a continuous method of making ingots for rolling or extrusion by pouring the metal into a short mould. The base of the mould is a platform which is gradually lowered while the metal solidifies, the frozen shell of metal acting as a retainer for the liquid metal below the wall of the mould. The ingot is normally cooled by the impingement of water directly on the mould or on the walls of the solid metal as it is lowered. The length of the ingot is limited by the depth to which the platform can be lowered, hence, it is frequently called semi-continuous casting.
DC component – It is the constant, non-varying part of an electrical signal or wave-form. It represents the time-averaged value (or the zero-frequency component) around which an AC (alternating current) signal fluctuates. For example, if a signal averages 3V (volts), the DC (direct current) component is 3V regardless of how much the alternating current portion fluctuates.
DC condition refers to the steady-state, unidirectional flow of electrical charge in a circuit. It is used in electronics to establish stable operating points (bias) for components like transistors and amplifiers, ensuring they function correctly before processing fluctuating signals.
DC converter – It is an electronic circuit which takes a direct current (DC) power source and changes it to a different voltage level. It is necessary for managing and providing stable power to different components in electronic devices, such as lowering a battery’s voltage to power a micro-controller.
DC generator – It is an electro-mechanical machine which converts mechanical energy into direct current (DC) electrical energy. It operates on the principle of electro-magnetic induction, where a rotating armature cuts through a magnetic field to induce a unidirectional electrical current.
DC intermittent non-capacitive arc – It is a low-voltage electrical discharge used in spectrochemical analysis to vapourize the sample material. Each current pulse has the same polarity as the previous one and lasts for less than 0.1 second.
DC-KCB process – It is a highly efficient, combined-blowing metallurgical converter system developed by JFE Steel Corporation (formerly Kawasaki Steel) for modern stainless-steel production. It is mainly used to rapidly decarburize molten iron with high carbon content (higher than 5 %) without oxidizing valuable chromium.
DC link capacitor – It is a specialized energy storage component situated between the input (e.g., a rectifier or battery) and the switching output (e.g., an inverter or motor drive) in power electronics. It acts as a buffer to stabilize voltage, smooth current ripples, and balance rapid power demands.
DC link voltage – It is the electrical potential (measured in volts) across the intermediate direct current (DC) bus connecting two power conversion stages, such as a rectifier and an inverter. It serves as a stabilized energy buffer, smoothed by a capacitor, to minimize voltage ripples and ensure smooth power delivery to the load. In majority of the industrial applications (like variable frequency drives or uninterruptible power supply systems), the direct current link voltage is directly related to the peak value of the alternating current input voltage.
DC loss – It refers to the reduction of electrical power or energy efficiency in a direct current (DC) system as it travels from a source to a load. It mainly occurs because of wiring resistance, heat dissipation, voltage drop, and electrical machine inefficiencies.
DC machine -It is an electro-mechanical energy converter which operates on direct current. It functions interchangeably in two ways namely as a DC (direct current) motor (converting electrical energy into mechanical rotation) or as a DC (direct current) generator (converting mechanical energy into electrical power).
DC microgrid – It is a localized power distribution network which uses a common DC (direct current) bus to connect distributed energy resources (like solar panels and fuel cells) directly with energy storage (batteries) and electrical loads. It operates independently or connected to a larger main grid. Since modern power generators (such as solar photo-voltaics and battery storage) natively produce DC (direct current) power, a direct current microgrid is highly efficient. It eliminates the need for multiple conversion stages between alternating current and direct current, considerably reducing energy losses during distribution.
DC motor – It is an electrical machine which converts direct current (DC) electrical energy into mechanical energy. It relies on the fundamental principle of electro-magnetism i.e., when a current-carrying conductor is placed in a magnetic field, it experiences a mechanical force.
DC network – It refers to an interconnected system of direct current (DC) power sources and electrical components (like resistors, capacitors, and inductors) through which electric charge flows in only one direction.
DC offset – It is an unwanted, steady direct current (DC) voltage which shifts an alternating current (AC) signal away from its zero-volt base-line. Instead of oscillating equally above and below zero, the entire wave-form is biased upward (positive) or downward (negative), leading to distortion, clipping, and equipment strain.
DC plasma excitation – The use of a high-temperature plasma jet to excite an element in a sample, for example, for atomic emission spectroscopy.
DC power transmission – It is the process of transferring bulk electrical energy from a generation source to a load using unidirectional current. Predominantly used in high voltage direct current (HVDC) systems, it works by converting AC (alternating current) to DC (direct current) for long-distance transport, then converting it back to alternating current for local distribution. Since it bypasses the physical limitations of alternating current transmission, direct current transmission is highly efficient for transferring massive quantities of electricity over long distances, such as from remote renewable energy projects to urban centres.
DC resistance – It is the opposition a material or component offers to the flow of steady direct current (DC). Determined by physical properties like material resistivity, length, and cross-sectional area, it is calculated using Ohm’s law as ‘Rdc = V/I’. It remains constant unless affected by temperature.
DC side capacitor – It is normally known as a DC-link capacitor. It is a central energy buffer and filter placed between the input (rectifier) and output (inverter) stages of power converters. It smooths out voltage fluctuations (ripple), stores energy, and decouples the power supply from rapid switching loads.
DC supply – It is a device which provides a steady, unidirectional flow of electrical energy. It typically converts high-voltage alternating current (AC) from standard wall outlets into stable, lower-voltage DC (direct current) to power sensitive electronic components like micro-controllers, motors, and batteries.
DC system – It provides a steady, unidirectional flow of electric charge where voltage and current maintain a constant polarity. Unlike alternating current (AC), which periodically reverses direction, DC (direct current) is natively produced by batteries, fuel cells, and solar panels, and is the standard format for charging and energy storage.
DC to DC converter – It is an electronic circuit which takes a direct current (DC) input and converts it to a different direct current voltage level. It acts as a crucial power management component, allowing systems to safely step down (lower), step up (raise), or stabilize voltage for sensitive electronic components.
DC voltage – It is an electrical potential which pushes current consistently in one direction, without alternating or reversing. Since it provides a steady, reliable flow of power, it is the standard type of voltage used to power and charge almost all sensitive electronic devices, including smart-phones, laptops, and electric vehicles.
DC voltage source – It is an electrical component which provides a constant electrical potential difference. It maintains fixed positive and negative terminals, driving a continuous, unidirectional flow of current through a circuit. Common examples include batteries, solar cells, and DC (direct current) power supplies.
Deacetylation degree – It refers to the percentage of acetyl groups removed from a polymer, indicating the extent of modification in its chemical structure, as exemplified by the chitosan samples with a deacetylation degree of 90 % and above.
Deactivation – It is the process where a component, system, or material loses its effectiveness, structural integrity, or operational function over time. It refers to the reduction in effectiveness or activity of a catalyst, which can occur as a multiscale event influenced by various factors, including operational conditions like high current densities. It is also the process of prior removal of the active corrosive constituents, normally oxygen, from a corrosive liquid by controlled corrosion of expendable metal or by other chemical means, thereby making the liquid less corrosive.
Dead-band – It means that the quantity of power supply of an actuator can be varied without initiating valve obturator motion. The area of a signal range or band where no action occurs. The technical term for dead-band is hysteresis. Dead band, also called dead zone, is also a specific range of input values within which a system produces no observable output or corrective action. It acts as a deliberate or unavoidable ‘buffer’, preventing a system from constantly overreacting to minor fluctuations or back-ground noise.
Dead-burned – It is term applied to materials which have been fired to a temperature sufficiently high to render them relatively resistant to moisture and contraction. It is the state of a basic refractory material resulting from a heat treatment which yields a product resistant to the atmospheric hydration or recombination with carbon di-oxide.
Dead burned dolomite – It is also known as sintered dolomite. It is a dense, chemically stable refractory material produced by heating raw dolomite to extreme temperatures (typically 1,400 deg C to 1,800 deg C). This prolonged, intense heating drives off all carbon di-oxide and shrinks the material, rendering it highly resistant to hydration and basic slags.
Dead-burned magnesite – It is the granular product obtained by burning (firing) magnesite or other substances convertible to magnesia, upon heating above 1,450 deg C long enough to form dense, weather-stable granules suitable for use as a refractory or in refractory products.
Dead-burned refractory dolomite – It is the refractory grade doloma which is obtained by burning dolomite above 1,450 deg C long enough to form a dense hydration-resistant material composed mainly of lime and magnesia.
Dead centre – It is a position of a crank where the applied force is straight along its axis. It is also a type of lathe centre used for accurately positioning a work-piece on an axis.
Dead-end filtration – It is a process where a fluid is pushed perpendicular (vertically) through a filter medium or membrane. All incoming fluid is forced through, and the retained particles accumulate on the filter surface, eventually forming a filter cake.
Dead-end mode – It typically refers to dead-end filtration (or normal-flow filtration). It is a fluid flow configuration in membrane filtration where the liquid flows perpendicularly to the filter surface. All the fluid passes through the membrane, while retained particles build up on the surface as a ‘filter cake’. Since the accumulated particles eventually clog the membrane pores and reduce the flow rate over time, dead-end mode is normally an intermittent, batch-based process needing periodic cleaning or membrane replacement. It is frequently used in laboratory clarifications.
Dead head – It refers to a barren, impoverished, or unproductive zone within a mineral vein or deposit. In the context of dolomite, which is a calcium-magnesium carbonate mineral or rock, it describes sections where the valuable ore (such as iron or lead) peters out, yielding only waste rock, or becomes heavily mixed with soft, clay-like, or unusable material.
Dead loads – These are structural loads are because of the of the structures. These consist of a constant magnitude over time. They include the self-weight of structural members, such as walls, plasters, ceilings, floors, beams, columns, and roofs. Dead loads also include the loads of fixtures that are permanently attached to the structure.
Dead-man zone – It is the stagnant flow region (dead-man) which is a discontinuous mass of partially reacted coke particles in the centre part of the hearth.
Dead metal zone – It is a near-stagnant region of material which becomes pinned or trapped in corners during deformation. Since it is basically trapped, this metal does not flow through the die or exit the tool. Instead, it acts as a ‘false’ die or cutting edge over which the rest of the material flows.
Dead oil viscosity – It is the viscosity of crude oil at atmospheric (surface) pressure with no gas in solution, measured at the system’s temperature. It serves as the base value used to calculate live oil viscosity (oil with dissolved gas) and reservoir fluid flow behaviours.
Dead plate – It is a stationary surface integrated into the conveyor for material accumulation or redirection, demanding periodic assessments for wear and proper alignment.
Deadrise angle – It is the measurement of the degree of V-shape formed between the flat bottom of a boat’s hull and a horizontal plane. Typically measured at the stern (transom), a 0-degree deadrise indicates a completely flat bottom, while higher angles (e.g., 20-degree to 24-degree indicate a sharper, deeper ‘V’.
Dead soft – It is a temper of non-ferrous alloys and some ferrous alloys corresponding to the condition of minimum hardness and tensile strength produced by full annealing.
Dead state – It is the condition where a system is in complete thermal, mechanical, and chemical equilibrium with its environment (having the exact same temperature, pressure, and chemical composition). In this baseline condition, the system has no potential to spontaneously change or perform useful work.
Dead steel – It very frequently refers to fully killed steel. It is a type of molten metal which has been completely deoxidized prior to casting so that it solidifies quietly in an ingot mould without emitting gas.
Dead time – It is the total time during which the spectrometer is processing information and is unavailable to accept input data.
Dead-weight – It refers to an object of finite mass used to produce force through the earth’s gravitational field, normally used for maintaining force traceability in measurements ranging from milli-newtons to mega-newtons. However, it is unsuitable for low-force applications below 10 micro-newtons because of the handling difficulties and high relative uncertainties in weight measurement.
Dead-weight load – It is normally referred to as a dead load. It is the permanent, unchanging weight of a structure itself and any fixtures permanently attached to it. Unlike live loads (such as people, furniture, or wind), dead weight remains constant over time, making them the base-line for calculating structural integrity.
Dead-weight tester – It uses the most fundamental pressure measurement technique. It is favoured for the primary calibration of pressure sensors, or piston gauge. This device uses calibrated weights (masses) which exert pressure on a fluid (usually a liquid) through a piston. Dead weight testers can be used as primary standards because the factors influencing accuracy are traceable to standards of mass, length, and time. The piston gauge is simple to operate. The pressure is generated by turning a jack-screw which reduces the fluid volume inside the tester, resulting in increased pressure.
Dead zone – It is also called dead space. It is defined as the range of different input values over which there is no change in output value. It is that range of possible values for which the instrument does not give a reading even there is changes in the parameter being measured. Any instrument which shows hysteresis also displays dead space. However, some instruments which do not suffer from any substantial hysteresis can still show a dead space in their output characteristics. Backlash in gears is a typical cause of dead space. Backlash is normally experienced in gear-sets used to convert the translational motion to rotational motion.
Deaeration – It is the process of removing trapped or dissolved air and gases (especially oxygen and carbon di-oxide) from a liquid. It is mainly used in industrial boiler systems to prevent corrosion and oxidation.
Deaerator – It is a mechanical device used to remove dissolved gases, mainly oxygen and carbon di-oxide, from boiler feedwater. By heating the water and utilizing steam to strip away the gases, it prevents severe, rust-inducing corrosion in industrial steam-generating systems, considerably extending the life-span of boilers and piping.
Deagglomeration – It is the mechanical process of breaking apart clustered clumps or lumps of powders, crystals, or other bulk materials into their original discrete particles. It is used across several industries to restore product homogeneity, ensure smooth textures, and improve flow behaviour. Since it targets loosely bonded clusters rather than fracturing the actual primary particles, it is normally a gentle process used to separate rather than to grind or crush.
Dealloying – It is the selective corrosion of one or more components of a solid solution alloy. It is also called parting or selective leaching.
Dealuminification – It is also called dealuminization. It is a type of selective leaching or dealloying corrosion where aluminum is preferentially removed from an alloy (typically aluminum bronzes or copper-aluminum alloys). It leaves behind a porous, weak, and brittle copper-rich sponge, leading to severe mechanical failure.
De-asphalted oil – It is a refined, high-value liquid petroleum product extracted from heavy crude oil residues. It is produced through solvent de-asphalting (SDA), a process which uses light hydro-carbon solvents (like propane or butane) to dissolve lighter, valuable hydro-carbons while precipitating out heavy, contaminant-rich asphaltenes and resins. Since the heavy contaminants (sulphur, metals, and carbon) are removed, de-asphalted oil (DAO) is cleaner and lighter than the original residue.
Debinding – It is one of the main production steps in the ceramic and powder-metallurgical industries. It refers to the thermal or catalytic removal of additives used in steps prior to production such as casting.
Debond – It is a deliberate separation of a bonded joint or interface, normally for repair or rework purposes. It is also an unbonded or non-adhered region, a separation at the fibre-matrix interface because of the strain incompatibility.
Debonded length – It is the specific section of a reinforcing element, such as a prestressing strand, ground anchor, or fibre, intentionally separated or prevented from bonding with the surrounding material (like concrete or grout). It is designed to control stress concentrations, prevent premature cracking, or allow for controlled movement.
Debonding – It is the process of separating materials or layers which have been previously joined by an adhesive, weld, or mechanical bond. It can be intentional or unintentional (e.g., a protective coating peeling off because of the stress).
Debonding strain – It is the effective tensile or shear strain limit of a bonded interface. When a structural component is under stress, exceeding this critical strain value triggers a separation (debonding) between the bonded materials. It is mainly studied regarding structures repaired with externally bonded composites.
Debonding stress – It is the critical level of mechanical, thermal, or residual stress which causes the adhesive bond between two different materials (such as fibres and a matrix, or an adhesive and a substrate) to break, leading to separation or delamination. When materials, like composites, sandwich panels, or bonded retrofits, are subjected to loading, stress concentrations develop at the interfaces. Debonding stress is the specific threshold at which the bond strength is overcome, frequently triggering interfacial fracture energy which propagates a crack between the layers.
Debossing – It is the process of creating recessed relief images and designs in materials. A debossed pattern is sunken into the surface of the material but might protrude somewhat on the reverse side. The process consists of depressing (in a blanking die) a portion or portions of the material below the ordinary surface level, normally to form lettering or decoration. Sometimes the background, rather than the lettering itself, is debossed, leaving the letters at the original level of the material, hence giving the appearance of embossing, otherwise the lettering itself is pressed down, giving the appearance of engraving.
Debris – It refers to scattered fragments, particulate matter, or waste materials generated by destruction, wear, or natural processes. It can mean residual building rubble, microscopic particles in mechanical systems, or natural geological sediment.
Debris, wear – It is the particles which become detached in a wear process.
Debugging – It is the process of identifying, analyzing, and removing errors or ‘bugs’ in software and hardware. Its main goal is to ensure that a system behaves and performs exactly as intended.
Debugging process – It is a systematic approach to diagnosing failures by observing the issue, formulating hypotheses, making predictions, and testing those hypotheses through experiments and further observations. It involves an iterative cycle of generating new hypotheses to understand and resolve the failure.
Debugging tool – It is a software programme used to identify, isolate, and resolve errors (bugs) in software applications. It allows developers to pause programme execution, inspect system memory and variable values, and execute code line-by-line to understand how the programme behaves at runtime.
Debulking – It is compacting of a thick laminate under moderate heat and pressure and / or vacuum to remove most of the air, to ensure seating on the tool, and to prevent wrinkles.
Deburring – It is the removing of burrs, sharp edges, or fins from metal parts by filing, grinding, or rolling the work in a barrel containing abrasives suspended in a suitable liquid medium. It is sometimes called burring.
Debye force – It is an inter-molecular attraction occurring when a permanent dipole distorts the electron cloud of a neighboring atom or molecule, inducing a temporary dipole. It is a component of the van der Waals forces and plays a fundamental role in understanding non-bonded interactions in materials.
Debye interactions – These are attractive dipole-induced dipole interactions between a permanent molecular dipole and a neutral, non-polar atom or molecule. They are a specific type of van der Waals inter-molecular force which governs how different species behave and attract each other.
Debye length – It is the characteristic distance over which mobile charge carriers (like electrons in a plasma or ions in a solution) screen out external electric fields. It defines the spatial scale over which charge imbalances are neutralized, forcing the medium to remain electrically neutral on a larger scale.
Debye model – It is a method to estimate phonon contribution to the specific heat (heat capacity) in a solid. It treats the vibrations of the atomic lattice (heat) as phonons in a box in contrast to the Einstein solid model, which treats the solid as several individual, non-interacting quantum harmonic oscillators. The Debye model correctly predicts the low-temperature dependence of the heat capacity of solids, which is proportional to the cube of temperature.
Debye-Scherrer method – It is a method of X-ray diffraction using monochromatic radiation and a polycrystalline sample mounted on the axis of a cylindrical strip of film.
Debye ring – It is a continuous circle, concentric about the undeviated beam, produced by mono-chromatic x-ray diffraction from a randomly oriented crystalline powder. An analogous effect is obtained using electron diffraction.
Debye specific heat function – It estimates the phonon (lattice vibration) contribution to the heat capacity of a solid. It models the solid as a continuous elastic medium and defines molar heat capacity at constant volume.
Debye T-cube law – It states that at very low temperatures, the specific heat (or heat capacity) of a solid is directly proportional to the cube of its absolute temperature. It accurately describes how vibrations in a crystal lattice behave as the temperature approaches absolute zero.
Debye temperature – It is a fundamental material property representing the temperature scale of a crystal’s highest possible mode of atomic vibration. It marks the transition point for how a metal’s crystal lattice absorbs thermal energy and behaves.
Decalescence – It is a phenomenon, associated with the transformation of iron to iron on the heating (super-heating) of iron or steel, revealed by the darkening of the metal surface owing to the sudden decrease in temperature caused by the fast absorption of the latent heat of transformation.
Decant – It means to draw off (a liquid) without disturbing the sediment or the lower liquid layers. While pouring metal from one vessel to another, it is pouring off molten metal without disturbing the sludge.
Decantate – It is the liquid or substance which has been decanted. It refers specifically to the clearer, lighter liquid which is carefully poured or drawn off after separating from a denser liquid or solid sediment.
Decantation – It is a mechanical separation process used to isolate mixtures of immiscible liquids or solids and liquids. By allowing gravity to settle the denser components, the lighter, clearer liquid (the decantate) can be gently poured off or siphoned, leaving the sediment or heavy liquid behind.
Decanted oil – It is also known as slurry oil or clarified oil. It is a heavy, low-value by-product generated during petroleum refining. It comes from the bottom of the ‘fluid catalytic cracking’ (FCC) unit. Since it is dense and viscous, it is typically used as a blending component for heavy fuel oil or as a feedstock for carbon black. Decanted oil (DO) is the lowest priced product and the goal is to reduce its yield. Its yield depends largely on the quality of the feedstock and the conversion level. Decanted oil properties vary greatly, depending on the feedstock quality and operating conditions.
Decanter -It is a mechanical device which improves the separation of solids and liquids by utilizing centrifugal force, achieving sedimentation at an acceleration rate 2,000 to 5,000 times higher than gravity, while continuously conveying solids from the unit.
Decanter centrifuge – It is an industrial continuous-sedimentation machine which separates solid particles from a liquid slurry using high-speed rotation. By replacing gravity with centrifugal force, frequently generating 2,000 to 5,000 times higher than gravity, it rapidly presses denser solids outward while discharging clarified liquid, dramatically reducing separation time.
Decanting – It is the process of separating immiscible substances (e.g., oil and water) or liquids from settled solids (e.g., sludge and water). The heavier, denser material is left behind while the lighter, clearer supernatant liquid is carefully poured or drawn off the top.
Decapsulation – It refers to the process of removing the packaging of a semi-conductor device to enable analysis at the chip level, utilizing methods such as mechanical grinding and chemical solvents to dissolve or soften the packaging material. This process allows for the examination of the chip’s internal features and can involve techniques like etching to selectively reveal different layers without damaging deeper structures. It also refers to the stripping communication headers from network packets to reveal the underlying data payload.
Decarbonation – It is a reaction involving the decomposition of carbonate minerals, such as calcite and dolomite, resulting in the release of carbon di-oxide (CO2). An example includes the reaction of calcite with quartz to form wollastonite while emitting carbon di-oxide. It is also the process of reducing or eliminating net carbon di-oxide and greenhouse gas emissions, normally by transitioning to renewable energy, improving efficiency, and capturing carbon. Decarbonation is also the chemical or mechanical removal of carbon deposits inside an engine (e.g., on cylinder heads and pistons) to restore efficiency. It is also the removal of carbon from steel to change its hardness.
Decarbonization – It is the process of reducing and eliminating carbon di-oxide (CO2) and other greenhouse gas emissions from the atmosphere. The main goal is to halt global warming by transitioning to clean energy sources and balancing remaining emissions with active carbon removal to reach ‘net-zero’.
Decarburization – It is the loss of carbon from the surface layer of a carbon-containing alloy because of the reaction with one or more chemical substances in a medium which contacts the surface.
Decarburization process – It is typically performed in vessels like an argon oxygen decarburization (AOD) converter or a basic oxygen furnace (BOF). Oxygen is injected to react with the carbon in the metal melt, forming carbon mono-oxide gas (CO) which escapes the system. The remaining chemical debris floats on the surface of the molten metal, forming the decarburization slag.
Decarburization slag – It is the oxide by-product generated when excess carbon is deliberately removed from molten iron or high-carbon alloys to produce steel. This highly basic slag captures oxidized carbon and impurities, and is frequently managed or recycled to recover valuable alloying elements like chromium.
Decay constant (lambda) – It is the constant in the radioactive decay law dN = -lambda Ndt, where ‘N’ is the number of radioactive nuclei present at time ‘t’. The decay constant is related to half-life t(1/2) by the expression t(1/2) = ln2/lambda.
Decay, radioactive – It is the decrease in the radioactive nature of any material with the passage of time. This is because of the spontaneous emission from the atomic nuclei of either alpha or beta particles and is frequently accompanied by gamma radiation.
Decay time – It is the time it takes for a physical quantity (like voltage, sound, or material strength) to reduce to a specific fraction of its initial value, typically 1/e (around 36.8 %). Decay time also refers to the interval needed for a radioactive sample to reduce by half. This is known as the half-life. For instance, cobalt-60 has a half-life of 5.26 years. After this period, a sample of cobalt-60 halves in quantity, emitting half of its initial radiation.
Deceleration – It is the rate at which an object slows down, fundamentally defined as negative acceleration. It occurs when an object’s velocity decreases over time, meaning the acceleration vector points in the opposite direction of the object’s motion.
Deceleration period – In cavitation or impingement erosion, it is the stage following the acceleration period or the maximum rate period (if any), during which the erosion rate has an overall decreasing trend although fluctuations can be superimposed on it.
Decentralization – It refers to a system architecture where control, processing, and decision-making are distributed across multiple independent nodes or controllers rather than concentrated in a single central authority. It eliminates single points of failure, making systems highly resilient, scalable, and autonomous.
Decentralized control – It is a system or management approach where decision-making authority, operational control, and data processing are distributed among multiple independent nodes or local entities rather than being concentrated in a single central authority. It eliminates single points of failure, enabling greater resilience, scalability, and localized responsiveness. Decentralized control is a control approach where each local controller autonomously determines its actions based on local measurements, allowing for optimal operation of individual units without reliance on communication among them. This structure improves autonomy and stability while facilitating scalability but can compromise the overall performance of the system.
Decentralized control system – It is an architectural framework where decision-making and process regulation are distributed among autonomous local nodes or subsystems. Instead of relying on a single master computer, individual controllers make localized decisions based on immediate data, collaborating to achieve broader operational goals. Decentralized control uses only local information to find optimal solutions through iterations. Coordination techniques are used by local controllers.
Decentralized hydrogen production – It refers to generating hydrogen energy locally at or near the point of consumption. Instead of massive central plants which need long-distance transportation, this approach relies on smaller, modular systems, like compact water electrolyzers, powered by localized renewable sources (e.g., solar, wind) to supply individual facilities or refueling stations. By producing hydrogen exactly where it is needed, one can eliminate the costs and emissions associated with long-haul pipeline transmission or trucking. This modular approach is highly scalable and is increasingly utilized in heavy manufacturing, remote power grids, and zero-emission transportation.
Decentralized design – It is a framework where authority, data, and decision-making are distributed across multiple independent nodes rather than concentrated in a central server or hierarchical leader. It eliminates single points of failure, enabling systems to become highly scalable, fault-tolerant, and resilient to censorship.
Decentralized energy resource – It refers to small-scale power generation and storage systems located close to where energy is consumed. Unlike traditional power grids that rely on massive, distant power plants, decentralized energy resources (DERs) allow homes, organizations, and communities to generate, store, and manage their own electricity.
Decentralized energy system – It generates power close to where it is consumed, rather than at massive, distant power plants. It relies on distributed energy resources (DERs), such as rooftop solar panels, wind turbines, and battery storage, allowing homes and organizations to both consume and feed excess electricity back into the grid.
Decentralized market – It is a system where buyers and sellers transact directly with one another without relying on a central authority, exchange, or middleman. Instead of consolidating trades in one physical location or platform, participants interact over a distributed network.
Decentralized multi – It refers to a system which operates without a central authority, utilizing multiple authorities to manage and verify transactions or signatures. This approach improves privacy and unforgeability in decentralized settings.
Decentralized network – It is an architecture where control, processing, and decision-making are distributed across multiple independent nodes rather than relying on a single central authority. This structure eliminates single points of failure, making the system highly resilient, scalable, and secure.
Decentralized peripherals – It is used to operate sensors and actuators through a centralized controller in production (factory) automation applications. It is used to describe distributed input / output devices connected through a fast serial data link with a central.
Decentralized procurement – It allows individual stakeholders to make purchases for their departments, unlike in centralized procurement operations, where all purchasing is conducted by a central procurement team. Decentralized procurement can work well, particularly when teams specialize in different product categories, since it places decision-making power into the hands of department buyers. The choice of a centralized or decentralized procurement model depends on the organizational priorities. In some cases, an organization can leverage both models and combine their best features.
Decertification – It refers to the official revocation of a previously granted certification, license, or standard approval for an engineer, organization, product, or system. It revokes the legal right or credential to perform specific engineering tasks, operate under specific safety standards, or supply certified materials.
Decibel – Decibel (dB) is a unit which is used to measure sound intensity and other physical quantities. A decibel is one tenth of a bel (B), a unit named after Graham Bell, the inventor of the telephone. Its logarithmic scale is convenient to represent the entire range of human hearing.
Decibel (dB) scale – It is a logarithmic unit used to measure the intensity or volume of sound. Since the human ear can detect a massive range of sounds, the scale compresses this wide range into a manageable span, typically starting at 0 dB (the threshold of human hearing).
Decile – Deciles are used to divide a numeric variable into 10ths, whereas the quartiles divide it into quarters, and percentiles into 100ths. An approximate value for the ‘rth’ decile can be read from a 6 cumulative frequency graph as the value corresponding to a cumulative relative frequency of 10r %. So, the 5th decile is the median and the second decile is the 20th percentile.
Decimal number – It is a number in the base-10 number system which uses a dot (the decimal point) to separate the whole number part from the fractional part. For example, in the decimal number 11.2, 11 is the whole number part and 2 is the fractional part.
Decimation filter – It is a digital signal processing component which reduces a signal’s sampling rate. It achieves this through a two-step process: applying a low-pass anti-aliasing filter followed by down-sampling (discarding excess samples), which conserves computational resources and prevents the distortion of out-of-band signals.
Decimator – It is defined as a device or process which reduces the sampling rate of a signal by selectively removing samples, frequently incorporating a low-pass filter to prevent aliasing of higher frequency components.
Deciphering – It is the process of translating or converting encoded, corrupted, or obscure data into an understandable, readable format. This can refer to cybersecurity decryption, hardware reverse engineering, or analyzing obscured technical readings.
Decision – It is a structured transformation of information under constraints, uncertainty, and time. It involves identifying options, predicting their outcomes, and mathematically or logically ranking those options to select the most suitable, scientifically-sound course of action. A robust decision is driven by measurable criteria and mainly focuses on technical feasibility, system performance, safety needs, and compliance with industry standards.
Decision aid system – It is an interactive software or tool designed to assist professionals in making informed choices. It aggregates data, runs predictive models, and presents options with their associated risks and benefits to guide human decision-making.
Decision analysis – It is a systematic approach to map out optimal choices under conditions of uncertainty by evaluating costs, probabilities, and outcome measures such as quality-adjusted life years. It includes methods like sensitivity analysis to assess the range of possible outcomes and risks associated with decisions.
Decision authority – Decision authority is the designated right, power, or official responsibility to make a final choice and be accountable for its outcome. It typically defines who has the final say, rather than merely influencing or recommending, within governance structures, corporate policies, or legal frameworks. Decision authority gives approvals by assessing operational risks, ensuring that decisions are made based on comprehensive information regarding known risks and compliance with pre-defined risk acceptability criteria.
Decision boundary – It is a conceptual or geometric surface which separates different classes in a classification model. Any data point falling on one side of the boundary receives one classification label, while points on the opposite side receive a different label.
Decision circuit – It is an electronic or mathematical component which determines whether an incoming, potentially noisy signal corresponds to a binary state (such as a logical 0 or 1) by comparing it to a threshold value. It is widely used in signal processing to clean up data, reduce jitter, and strengthen weak signals.
Decision device – It refers to the hardware or software component in a digital receiver which samples a noisy, distorted signal. It determines the most likely intended data state (such as a logical 0 or 1) by comparing the signal to a specific threshold.
Decision feedback equalizer – It is a system which utilizes identified symbol feedback to generate a channel output estimate, compensating for inter-symbol interference (ISI) by subtracting the output of a finite impulse response (FIR) filter from the linear equalizer output. It uses previous symbol decisions to improve signal distortion handling without increasing noise in distorted frequency bands.
Decision fusion – It is the process of integrating the outputs of multiple independent classifiers or data sources to produce a single, coherent consensus. By coalescing diverse inputs, it improves the accuracy, reliability, and robustness of a classification or prediction system.
Decision maker – Decision maker is an individual or group with the authority and responsibility to choose a course of action from multiple alternatives. In organizational contexts, decision makers are executives or managers who control budgets, approve purchases, and set strategic goals.
Decision making costs – These costs are those costs which are used by the management for the purpose of decision making. Example of such costs are cost of a project, and costs to develop a product.
Decision matrix – It is a formalized process by which design concepts or materials are ranked prior to a selection decision. Decision matrix is a structured tool used to evaluate and compare multiple options against a set of predefined, weighted criteria. By assigning scores to each option, it transforms subjective choices into objective, data-driven outcomes, removing emotion and bias from the decision-making process. It is also known as a Pugh matrix, grid analysis, selection matrix, or problem-solving matrix.
Decision process – It is the structured sequence of cognitive, analytical, and practical steps taken to evaluate options and select a single course of action from multiple alternatives. It transforms raw information and objectives into a deliberate choice to solve a problem or capitalize on an opportunity.
Decision regions – These are defined as specific areas within the input space which correspond to a unique output class, where all points in a region contain one and only one output class. Multiple decision regions can exist within an input space, each representing a different output class. Decision regions are specific areas in an input space where all points are assigned to the same category or output class by a classification model. They represent how a model ‘carves up’ data to make predictions.
Decision speed – It refers to the pace at which individuals or teams evaluate options and commit to a course of action. It balances rapid execution with analytical thoroughness, often serving as a competitive advantage when supported by clear decision-making frameworks.
Decision tree – It is a hierarchical, flowchart-like graphical model used to map actions, conditions, and potential outcomes systematically. It serves two completely distinct functions namely as a structured tool for design logic, risk analysis, and project management, and as a supervised machine learning algorithm for automated classification and regression.
Decision tree analysis – It is a diagrammatic technique used to illustrate a chain of decisions and to examine the implications of multiple decision-making or situational outcomes.
Decitex – It is abbreviated as dtex. It is a standard unit of measurement used to define the linear mass density, or thickness, of fibres and filaments. It is defined as the weight in grams of 10,000 meters of a yarn or fibre.
Deck – It normally refers to the supported functional super-structure. It is a flat surface capable of supporting weight, similar to a floor, but typically constructed outdoors, frequently elevated from the ground. In mining, it is the area around the shaft collar where men and materials enter the cage to be lowered underground.
Deck plate – It is a structural component made of steel which supports dynamic loads, such as wheel loads from traffic, and is frequently connected to longitudinal stiffeners or stringers through welds. The quality of these welds is important, as poor quality can lead to fatigue and premature failures in the deck.
Deck structure – It serves as a structural framework to support the floor. It is an elevated or horizontal, weight-bearing platform. Deck structure is above and between the columns and is referred to as the super-structure.
Deck weight – It defines the total gravitational force a deck exerts or is designed to support. It is split into dead weight (the permanent, static weight of the platform’s materials) and live weight (temporary, moving loads like people, furniture, or snow).
Decline – In mining, it is a sloping underground opening for machine access from level to level or from surface, it is also called a ramp.
Decline curve analysis – It is a reservoir engineering method used to predict future oil and gas production by analyzing historical data. By fitting past production rates to mathematical models, operators can forecast well life-spans, estimate recoverable reserves, and evaluate the economic viability of an asset.
Decline conveyor – It is a conveyor system where pallets and products travel on a downward slope, needing specialized maintenance for smooth operation.
Decobaltification – It is the selective corrosion or leaching of cobalt from a cobalt-base alloy (like stellite) or a cemented carbide (such as tungsten carbide). It leaves behind a weakened, porous, and brittle metal structure which is highly susceptible to failure.
Decoded bit – It typically refers to an originally transmitted 1 or 0 which has been recovered from encoded, compressed, or corrupted data during a receiver’s decoding process. It is the final, usable binary value extracted after the system processes parity checks, error corrections, or compression algorithms.
Decoded image – It is the uncompressed, raw visual data generated when a device’s processor translates a compressed digital file into a format of pixels which a screen or operating system can display. The decoding process fundamentally bridges the gap between how an image is stored and how it is displayed.
Decoder – It is the inverse of an encoder. It acts as a processing component which translates coded, compressed, or encrypted data back into its original, intelligible format (e.g., plain text, visual images, or audio).
Decoder implementation – It refers to the physical or structural construction of a decoder circuit. It translates coded binary inputs (normally n lines) into a distinct set of active outputs (up to 2 to the power ‘n’ lines) using logic gates like AND, OR, and NOT. Exactly one output goes high for each unique.
Decoder side – It refers to the receiving end of a data transmission system where this interpretation, processing, and reconstruction occurs.
Decoding algorithm – It is a computational method used to convert encoded or compressed data back into its original, understandable format. It serves as the reverse operation of an encoding algorithm, evaluating structured tokens or transmitted signals to reconstruct the original text, media, or message.
Decoding circuit – It is a combinational logic circuit which reverses encoding by translating an n-bit binary input into a maximum of ‘2 to the power n’ unique output lines. It activates exactly one specific output corresponding to the binary value of the input, while keeping all other outputs inactive.
Decoding complexity – It normally defines the quantity of computational effort, resources, or central processing unit (CPU) instructions needed by a system to translate an encoded signal, data stream, or algorithm back into its original, understandable format. It balances encoding design and directly impacts device battery life and processing latency.
Decoding function – It is a mathematical or programmed routine which reverses an encoding process, converting compressed, encrypted, or machine-readable data (like binary bits) back into its original, human-readable format (such as text, an image, or an audio signal).
Decoding method – It refers to the process used to interpret received codewords in digital communications, classified into hard decision decoding, where each symbol is determined as either 0 or 1, and soft decision decoding, which generates analog information for recovering the original message.
Decoding procedure – It is the algorithmic or systematic process of translating encoded, compressed, or encrypted data back into its original, usable format. It acts as the reverse of encoding, allowing machines, systems, or individuals to understand, interpret, or render raw data, text, audio, or video correctly.
Decoding technique – It is the algorithmic or cognitive process of converting encoded, compressed, or symbolic information back into its original, understandable format. It is the reverse of encoding and is fundamental across computer science, data transmission, and human linguistics to interpret data.
Decohesion – It is the process of creating a pair of free surfaces where a grain boundary or second-phase boundary existed previously.
Decohesive rupture – It is a brittle fracture which shows little or no bulk plastic deformation and does not occur by dimple rupture, cleavage, or fatigue. This type of fracture is normally the result of a reactive environment or a unique micro-structure and is associated almost exclusively with rupture along grain boundaries.
Decoiler – It is also called uncoiler. It is a specialized material-handling machine which holds, supports, and continuously unwinds coiled materials, such as metal strip, into a manufacturing production line. It sits at the front end of automated systems, feeding raw material smoothly into downstream equipment like presses, shears, and roll formers.
Decommissioning – It is the final phase in the life cycle of a nuclear installation covering all activities from shutdown and removal of fissile material to environmental restoration of the site through to its agreed end state, and / or it is the process of closing down a facility followed by reducing residual radioactivity to a level which permits the release of the property for unrestricted use.
Decommissioning plan – It is a plan for the decommissioning of a nuclear facility.
Decommissioning waste management plan – It is a part of the decommissioning plan which sets out the steps and costs involved in disposal of the waste at the time of decommissioning a nuclear power station.
Decompose – It means to break down into basic components, given the right conditions of light, air, and moisture. It refers to materials such as food and other plant and animal matter.
Decomposition – It is the separation of a compound into its chemical elements or components. It is the process of breaking down a complex metal compound or ore into simpler substances or pure metals. This is typically achieved using high temperatures (thermal decomposition) or electricity (electrolysis) to extract raw metals from ores or to refine metal microstructures. Decomposition is also the process of breaking a complex concept, or problem into smaller, more manageable parts.
Decomposition coefficient – It is a value which quantifies the rate or extent at which a complex entity (like a signal, chemical compound, or organic matter) breaks down into simpler constituent parts.
Decomposition concept -It refers to the methodology of breaking down flow properties into average and fluctuating components, allowing for the derivation of macroscopic governing equations in porous media analysis, where the medium is considered rigid and saturated by an incompressible fluid.
Decomposition furnace – It is an industrial reactor which breaks down chemical compounds into simpler substances or gases using high heat (thermal decomposition). It is widely used to drive off volatiles, recover materials, or eliminate harmful pollutants.
Decomposition level – It refers to a specific stage or layer of granularity when breaking down a complex entity, like a dataset, signal, software system, or mathematical problem, into its fundamental components. The level dictates how far down or abstract the breakdown goes. The selection of an appropriate decomposition level is frequently influenced by different criteria, including entropy metrics which gauge the information content and surprise in the data.
Decomposition potential – It is the potential of a metal surface necessary to decompose the electrolyte of a cell or a component thereof.
Decomposition process – It is a core extractive process in which a chemical compound (such as an ore) is broken down into simpler substances or its constituent elements (e.g., separating a metal from oxygen, carbon, or sulphur). It is typically driven by intense heat (thermal decomposition), electricity (electrolysis), or chemical reactions to extract and refine metals.
Decomposition voltage – It is the minimum external voltage needed to cause the continuous electrolysis of an electrolyte in a cell. It is the threshold point where a sustained electrical current begins to flow and continuously separate chemical compounds into their elemental components.
Decompression – It is the act or process of reducing, releasing, or relieving pressure.
DECON – It is a method of decommissioning in which the equipment, structures, and portions of a nuclear facility and site containing radioactive contaminants are removed. The contaminants are safely buried in a low-level radioactive waste landfill or decontaminated to a level which permits the property to be released for unrestricted use shortly after cessation of operations.
Decontamination – It is the process of removing contaminants from different items, such as metallic components and equipment, typically involving a combination of techniques selected based on a cost–benefit analysis and specific characteristics of the components to be treated. It is also the reduction or removal of (radioactive) material from any structure, area, object, or person. Decontamination can be accomplished by treating the surface to remove or decrease the contamination.
Decontamination factor – It is a metric used to measure the effectiveness of a decontamination process. It is calculated as the ratio of the initial level of contaminant (such as radioactivity or chemical concentration) to the final level of contaminant after cleaning. Decontamination factor (DF) is mathematically defined as ‘DF = Cinitial/Cfinal’.
Deconvolution – It is a computational process used to reverse the effects of blurring or distortion in signals and images. By mathematically modelling how a signal has been originally distorted, it reconstructs the original, uncorrupted data.
Decoration (of dislocations) – It is the segregation of solute atoms to the line of a dislocation in a crystal. In ferrite, the dislocations can be decorated with carbon or nitrogen atoms.
Decorative chromium plating – It is different from hard chromium plating in terms of thickness and the type of undercoating used. The average thickness of decorative plating is actually very thin, normally not more than 1.25 micrometers. A decorative chromium deposit is used mainly for its pleasing blue-white colour. Its highly reflective appearance is maintained in service since chromium can resist tarnish, chemicals, scratches, and wear. Decorative chromium plating baths normally produce deposits in the range of 0.13 micrometers to 1.25 micrometers in thickness. These deposits normally reproduce the finish of the substrate, or, in a multilayer system, the undercoating which is applied prior to the chromium layer. Optimum lustre of the final chromium deposit is got by plating the substrate coating to a uniformly bright condition.
Decorative coining – It is a precision, cold-forging process where intense compressive pressure is applied to a metal blank in closed dies. The material is forced to flow plastically into the die cavity to imprint highly intricate designs, sharp reliefs, and polished finishes without altering the bulk thickness.
Decorrelation – It is a data-transformation technique which reduces or completely removes the statistical dependencies (linear correlations) between random variables, signals, or features. By transforming correlated inputs into a new set of uncorrelated components, it simplifies data analysis, improves machine learning model performance, and increases compression efficiency.
Decoupled architecture – It is a software design approach where distinct components of a system (such as the frontend presentation layer and backend databases) operate independently. They communicate through application programming interfaces (APIs) or message queues rather than being tightly bound, allowing developers to update, scale, and deploy each layer individually.
Decoupled system – It is an architectural approach where components operate independently and communicate minimally through predefined interfaces. Modifying or failing one component does not disrupt the others, which allows individual parts to be scaled, maintained, and replaced without affecting the rest of the system. In software and system engineering, this concept is highly valued for its ability to isolate faults, speed up deployments, and support flexible technology stacks.
Decoupling capacitor – It is also called bypass capacitor. It is a capacitor placed between an active device’s power pin and ground. It acts as a local energy reservoir and high-frequency noise filter, providing instantaneous current to prevent voltage drops and shunting unwanted electrical noise to ground.
Decoupling frequency -It is also called self-resonant frequency. It is the specific frequency at which a decoupling component, such as a capacitor, effectively shunts high-frequency noise to ground. Below this point, it behaves capacitively. Above this point, parasitic inductance makes it act as an inductor, limiting its filtering ability.
Decoupling property – It defines how independently distinct components, variables, or functions can operate without relying on or interfering with one another. This principle allows engineers to alter, optimize, or scale a single parameter or sub-system without triggering cascading changes across the entire design.
Decreased reactivity – It normally refers to a reduction in a system’s or material’s propensity to undergo a specific transformation, interaction, or chemical change.
Decreasing plasticity under tension – It refers to the reduction of a material’s capacity to permanently deform without fracturing when subjected to pulling (tensile) forces. This limits the material’s ductility, its ability to stretch or elongate before breaking.
Dedendum – It is the radial distance from a gear’s pitch circle to its root circle (the bottom of the tooth space). It basically defines how deep a gear tooth extends below the pitch line and dictates the clearance needed to prevent the tip of a mating gear from bottoming out.
Dedicated bearer – It is an on-demand logical tunnel between a mobile device and the core network, established to guarantee specific ‘quality of service’ (QoS) for distinct traffic types, such as voice or video. It attaches to an existing default bearer without needing an extra IP (internet protocol) address.
Dedicated control channel – It is used for transmission of control information to / from a device. This channel is used for individual configuration of devices such as different handover messages. Dedicated control channel reserves a portion of wireless bandwidth for sending / receiving the control information. Although it is simple to implement, it has some reservations, too. When one of the sixteen channels is dedicated to control traffic, then it can waste 6 % of the overall bandwidth. Likewise, it can induce performance degradation in case of heavy load, interference and jamming on the control channel. Apart from that, a dedicated control channel can suffer from the ‘denial-of-service’ (DOS) attacks, where an intruder can flood the dedicated control channel with useless messages in an attempt to overburden it.
Dedicated equipment – It refers to specialized machinery, systems, or tools engineered or assigned exclusively for a single specific task, product, or production line. Unlike general-purpose machinery, it is optimized for repeatability and high throughput rather than flexibility.
Dedicated tooling – It refers to custom, single-purpose devices (such as moulds, dies, and fixtures) designed exclusively to manufacture or hold one specific part. While it needs higher upfront costs and longer production lead times than modular tooling, it is highly optimized for repeatability, speed, and long-term production.
Deep belief network – It is a generative deep learning model composed of multiple layers of stochastic (probabilistic) hidden variables. It is chiefly built by stacking multiple restricted Boltzmann machines (RBMs) on top of one another.
Deep Boltzmann machine – It is an undirected, generative, and stochastic deep neural network. It consists of one visible layer representing the input and multiple hidden layers. Unlike other networks, connections between nodes are undirected, allowing the model to learn highly complex, hierarchical representations of data in an unsupervised manner.
Deep cooling – It is a treatment technology which improves the mechanical properties of metal components through the regulation of thermodynamic coupling effects and the management of crystalline phase transformations, such as the conversion from residual austenite to martensite.
Deep cup-like parts – These refer to hollow, three-dimensional components (like cylindrical shells or pots) where the depth is higher than the diameter. They are typically manufactured by pressing a flat sheet of metal into a hollow die using a punch, causing substantial plastic deformation without fracturing or considerably thinning the material.
Deep defects – These refer to imperfections within a material which disturb the heat conduction process, leading to variations in surface temperature distribution compared to the surrounding area. These defects can be detected through temperature changes captured by infrared imaging.
Deep discharge – It refers to a hydro-metallurgical extraction technique where metals (like zinc or manganese) are deposited out of an electrolytic solution. The process involves drawing a continuous electric current through the electrolyte to completely (or deeply) exhaust the metal ions from the solution, recovering the targeted metal.
Deep drawability – It is a sheet metal’s ability to undergo severe plastic deformation into a deep, hollow, or cup-shaped geometry without tearing or wrinkling. It is measured by the limiting drawing ratio (LDR), where high values and high r-values (plastic strain ratios) indicate superior forming capability. Deep drawability is mainly governed by specific metallurgical properties and process mechanics.
Deep drawing – Deep drawing is a sheet forming process in which in its simplest form, a cylindrical shape or alike is produced from a thin disc of sheet metal by subjecting it to a compressive force (while it is held between a die and blank holder) through a circular punch which mainly work on the blank thickness. Deep drawing process is used to produce containers from flat circular blanks. The central portion of sheet of blank is subjected to pressure applied by punch into a die opening to get a sheet metal of needed shape without folding the corners. This normally needs the use of presses normally having a double action for blank holding force and punch force.
Deep drawing and ironing – It is a sequential metal-forming process used primarily to create hollow, thin-walled cylindrical objects like beverage cans. Deep drawing shapes a flat metal sheet into a cup, while ironing stretches and thins the cup’s walls to a uniform thickness while lengthening the part.
Deep drawing cup test – The deep-drawing cup test is as per International Organization for Standardization standard ISO 11531. The deep- drawing cup test is a sheet metal testing method in which a circular plate (round blank) is punched out of a sheet metal strip and then formed into a cup by a drawing die. The largest possible ratio between the diameter of the round blank and the diameter of the drawing die, which just allows the perfect production of a cup, is called the limiting drawing ratio ‘B-maximum’ and is a quality characteristic for the forming capacity of the sheet metal material. The ears, which form as a result of the flow properties of the material, are undesirable since they necessitate rework on the drawn products when they occur in practice.
Deep-drawing dies – These are specialized industrial tools used in sheet metal forming. They work in tandem with a punch and blank holder to shape a flat sheet metal blank into a seamless, three-dimensional, hollow part (such as a cup, cylinder, or sink) without causing wrinkles or tears.
Deep-drawing die materials – These are specialized alloys and metals used to construct the punches, dies, and blank holders required in the deep drawing process. These materials are engineered to withstand massive compressive and frictional forces while continuously shaping flat sheet metal into hollow, three-dimensional forms without tearing or wrinkling.
Deep drawing process – It is a sheet metal forming process where a flat blank is pulled into a die cavity by a punch, transforming it into a seamless, hollow shape. It qualifies as ‘deep’ drawing when the depth of the finished part exceeds its diameter.
Deep drawing sheet – It is the sheet which is produced with specific characteristics that permit deformation by deep drawing. Examples of these characteristics are softness, high ductility and low tensile strength.
Deep drawing steel – It is a high-quality low carbon steel possessing high ductility and desirable grain size which permits deep drawing.
Deep-draw mould – It is a mould having a core which is long in relation to the wall thickness.
Deep drawn enclosures – These are seamless, one-piece protective housings or shells formed by pressing a flat sheet of metal (a blank) into a die using a punch. It is a cold-working process which produces durable, leak-proof, and dimensionally stable components like cans, battery cases, or RF (radio frequency} shields.
Deep draw process – It is a sheet metal forming technique where a flat metal blank is forced into a die cavity by a punch. It shapes the metal into three-dimensional, seamless, hollow parts (like pots or cylinders) while preserving a uniform material thickness.
Deep draw stamping – It is a cold-working metallurgical process which transforms flat sheet metal into hollow, seamless, three-dimensional shapes. It is specifically defined as ‘deep’ when the depth of the finished part equals or exceeds its diameter.
Deep enclosures – These enclosures have the height to width ratios. These ration approach or exceed 0.75 to 1. At these ratios, the enclosure attains the characteristic proportions of a cavity and hence, can be classified arbitrarily as either an enclosure or a cavity.
Deep energy retrofit – It is an energy conservation project in an existing building which leads to an overall improvement in building performance. It can be characterized as a whole-building analysis and construction process which aims to reduce on-site energy use by 50 % or more using existing technologies, materials and construction practices. It leverages whole building approaches and integrative design to maximize energy efficiency and emissions reductions.
Deeper water depths – These refer to marine areas with water depths exceeding 400 meters, which are classified as deep water, while those over 1,500 meters are categorized as ultra-deep water, as per different definitions which have evolved over time in the oil and gas industry.
Deep etching – In metallography, it is macro-etching, especially for steels, for determining the overall character of the material, i.e., the presence of imperfections, such as seams, forging bursts, shrinkage-void remnants, cracks, and coring.
Deep excavation – It is the process of excavating below the ground surface for the construction of super-structures and underground engineering systems, needing careful design to maintain the stability of both the excavation system and surrounding infrastructures in urban environments.
Deep foundation – It is a type of foundation which transfers equipment loads to the earth farther down from the surface than a shallow foundation does to a subsurface layer or a range of depths. A pile or piling is a vertical structural element of a deep foundation, driven or drilled deep into the ground at the erection site of the equipment.
Deep-freezing – It is also called quick-freezing. It is an industrial process which rapidly reduces the core temperature of materials, metals, to -18 deg C or lower within minutes to a few hours. This ultra-fast cooling prevents large crystal formation, preserving the structural integrity, texture, and physical properties of the material.
Deep geological disposal – It is the permanent disposal of highly radioactive waste deep underground (typically 200 meters to 1,000 meters) in stable rock formations. It uses a multi-barrier system, combining durable waste packaging, engineered seals, and natural geology, to isolate hazardous materials from the biosphere without needing future human maintenance.
Deep geological repository – It is a nuclear waste repository excavated below 300 metres within a salt dome or bed-rock. It entails a combination of waste form, waste package and engineered seals which is designed to provide a high level of long-term storage without future maintenance.
Deep geothermal – It refers to geothermal systems which exploit thermal energy from depths higher than 400 meters, dealing with medium to high temperature and enthalpy.
Deep geothermal energy – It is the extraction of high-temperature heat from deep beneath the earth’s surface (typically deeper than 400 meters). This continuous, renewable baseload power, frequently accessed between 1,500 meters and 5,000 meters or more, is used to drive steam turbines for electricity generation.
Deep groove ball bearings – These are the most common type of rolling bearing. Thes are versatile, rolling-element bearings which feature deep raceway grooves. The curved race dimensions match the rolling balls, allowing them to minimize friction. The simple yet robust design allows the bearings to accommodate both radial and axial loads, making it versatile and ideal for high-speed, low-friction applications. These bearings are the most widely used bearing type globally because of their high-speed capability, low maintenance, and simple, non-separable design.
Deep ground bed – It is one or more anodes installed vertically at a nominal depth of 15 metres or more below the earth’s surface in a drilled hole for the purpose of supplying cathodic protection for an underground or submerged metallic structure.
Deep-hole drilling – It is a precision machining process used to create deep, narrow holes in metal where the depth-to-diameter ratio typically exceeds 10:1. It relies on specialized equipment, high-pressure coolant, and specific techniques to evacuate metal chips and maintain strict tolerances for straightness and surface finish. The process is fundamentally defined by its physical challenges and the specialized methods needed to overcome them.
Deep layer – It normally refers to a structural level located far beneath the surface or refers to the intermediate, multiple processing stages within an artificial neural network. Deeper layers are the stacked layers of neurons in a deep neural network which improve feature representation and classification capabilities, although they can complicate training because of the degradation problem, which is exacerbated as the network depth increases.
Deep learning – It is a subset of artificial intelligence and machine learning which uses multi-layered ‘neural networks’ inspired by the human brain. It autonomously learns complex patterns and representations from massive quantities of unstructured data, removing the need for humans to manually programme rules or features.
Deep mixing – It refers to a process which ensures a homogeneous temperature and chemical composition throughout a large volume of molten metal, typically through mechanical, pneumatic, or electro-magnetic stirring. It prevents stratification, accelerates reaction kinetics, and allows for the uniform distribution of alloying elements during primary production or refining. Deep mixing is also a ground improvement technique where in-situ soil is mechanically blended with a binder (like cement or lime) using a rotating shaft and mixing blades. This process solidifies weak soils to increase structural strength, reduce compressibility, and limit permeability for various geotechnical and environmental applications.
Deep mixing method – It is a technique which involves penetrating the ground by injecting and mixing stabilizing agents, such as cement and lime, using a rotating shaft or paddles, resulting in a column of treated soil with enhanced strength, reduced compressibility, and lower hydraulic conductivity.
Deep neural network – It refers to a multi-layered artificial intelligence model which maps complex process variables, such as alloy composition and temperature, to material properties or manufacturing outcomes. It extracts hidden, non-linear relationships from empirical data to optimize alloy design and predict structural performance. Deep neural networks (DNNs) are transforming traditional empirical research into data-driven modelling.
Deep ocean storage – It refers to the process of capturing anthropogenic carbon di-oxide (CO2) and isolating it in the sea bed or deep-water column at depths exceeding 3,000 meters. This relies on extreme hydrostatic pressure and low temperatures to lock away carbon for geologic timescales.
Deep reactive-ion etching – It is a highly anisotropic dry-etching technique used to create deep, steep-sided holes and trenches in substrates. It is mainly known for the Bosch process, which rapidly alternates between isotropic plasma etching and protective polymer deposition to achieve high aspect ratios and near-vertical sidewalls.
Deep red filter – It is an optical element which selectively transmits wave-lengths longer than around 600 nano-meters to 650 nano-meters while heavily absorbing or blocking shorter wave-lengths like blue and green. It functions as an optical long-pass filter, used in imaging, machine vision, and sensors to increase contrast, eliminate glare, and isolate specific spectral bands. It is also a gas filter in air pollution control, consisting of a loosely packed mat of fibrous materials. It is not practical where high grain loading is encountered.
Deep renovation – It is a comprehensive building refurbishment which reduces a structure’s total energy consumption and greenhouse gas emissions by at least 60 % to 80 % compared to pre-renovation levels. It achieves this by aggressively upgrading the building envelope (insulation, air barriers, high-performance windows) and integrating highly efficient mechanical systems. Unlike light renovations, deep renovations rely on a highly integrated, systems-engineering approach.
Deep reservoir – It refers to an underground geological formation which traps fluids, such as hydro-carbons, water, or geothermal steam, at substantial depths (typically higher than 3,500 meters to 4,500 meters). These formations need highly specialized drilling, completions, and reservoir modelling techniques to manage extreme pressures, high temperatures, and complex fluid dynamics.
Deep rolling – It is a mechanical surface treatment process which presses a highly loaded ball or roller tool onto a metal component. It induces deep plastic deformation, creates favourable compressive residual stresses, and work-hardens the material, which considerably increases fatigue strength and prevents crack propagation.
Deep-sea mining – It is the industrial extraction of critical minerals (such as nickel, cobalt, and manganese) from the ocean floor. It needs heavily specialized sub-sea robotics, hydraulic lift systems, and surface vessels designed to withstand extreme pressure, freezing temperatures, and complex fluid dynamics.
Deep steel desulphurization – It is a secondary metallurgical process which reduces sulphur impurities to ultra-low levels (typically 0.002 % or less). It is important for high-performance steels used in sour oil / gas environments and critical applications, preventing sulphur-induced embrittlement and cracking.
Deep tank – It is a specialized, multi-purpose compartment within an industrial facility designed to safely store liquids. Since they bear immense loads, deep tanks need specialized engineering elements such as scantlings, free surface effect, and cofferdams.
Deep trough – It is a term used for a troughing angle of 45-degree, rather 60-degree.
Deep ultra-violet (DUV) methods – These methods refer to processes and analytical techniques utilizing short-wavelength, high-energy ultraviolet light (typically between 100 nano-meters and 300 nano-meters). This spectrum allows for high-precision imaging, chemical analysis, and manufacturing at the nano-scale.
Deep water – It has two distinct meanings. In coastal and ocean engineering, it means water depths higher than half the surface wave length, where the sea bottom does not affect wave motion. In the oil and gas industry, it refers to depths exceeding 400 meters to 600 meters.
Deep-water drilling – It is the process of extracting oil and natural gas from beneath the ocean floor in water depths typically exceeding 200 meters. Depths beyond 1,500 meters are classified as ‘ultra-deep-water’. These operations need advanced floating rigs, robust subsea systems, and specialized pressure-control technologies.
Deep-water installation – It refers to the offshore engineering, placement, and commissioning of oil and gas structures (like drilling rigs, pipelines, or subsea manifolds) in water depths normally exceeding 200 meters to over 1,500 meters. It involves highly specialized vessels to safely secure massive infrastructure in extreme environments.
Deep-water production – It is the extraction of oil and gas from reservoirs located in water depths typically higher than 300 meters. Operations extending beyond 1,500 meters are classified as ultra-deep-water. These highly capital-intensive operations need advanced floating platforms, sub-sea systems, and specialized technologies to manage extreme under-water pressures and temperatures.
Deep-well Injection – It consists of deposition of raw or treated, filtered hazardous waste by pumping it into deep wells, where it is contained in the pores of permeable subsurface rock.
Deep X-ray lithography – It is an advanced micro-manufacturing technique which uses high-energy synchrotron radiation to transfer mask patterns into thick photoresists. It is highly regarded for its ability to produce micro-components with massive structural heights, parallel edges, and ultra-high aspect ratios (depth-to-width).
Default – It is a preset value, operating condition, or parameter that a system, software, or component automatically uses if the user or designer does not explicitly specify an alternative. Defaults are standardized to provide safe, functional starting points and streamline operations.
Default classification – It refers to a baseline or fallback category automatically assigned to data, documents, or physical assets when they lack explicit labels, cannot be analyzed by automated systems, or fall outside specific predefined rules. It acts as a safety-net to ensure systematic organization.
Default condition – It is the baseline state, parameter, or operating mode a system automatically reverts to when no user input, alternative configuration, or overriding signals are present. It ensures operational safety, system stability, and predictable performance. It also refers to a situation where a system or programme fails to perform as expected or encounters an error, leading to potential loss or disruption in operations.
Default model – It is a statistical framework used to estimate the probability of default (PD) over a specified period, incorporating both quantitative and qualitative aspects, and can use methods such as generalized linear models (GLMs) and machine learning techniques for model development and validation.
Default parameter – It is a predefined value assigned to a function or method parameter in software engineering. If a caller omits the corresponding argument during invocation, the system automatically applies this fallback value. It is an essential practice for simplifying function signatures and making application programming interfaces (APIs) backward-compatible.
Default unit system – It is the pre-set, standard framework of measurements, such as the International System of Units (SI), which software, modelling tools, or global organizations use automatically before a user manually changes it. These frameworks define coherent sets of base units (e.g., meters for length, kilograms for mass, seconds for time) and derived units (e.g., newtons for force, pascals for pressure). Setting a default system ensures that all mathematical calculations, simulations, and hardware imports remain dimensionally consistent without needing constant manual conversions.
Defect – It is an imperfection (deviation from perfection) which can be shown to cause failure by a quantitative analysis and which would not have occurred in the absence of the imperfection. In manufacturing, a defect is (ai a failure to conform to stated specifications, (ii) non-satisfaction of customer requirements, (iii) deviation from the norm, and (iv) when a product leaves the assembly line in sub-standard condition, differs from the manufacturer’s intended result, or differs from other ostensibly identical units of the same product line. It is also a discontinuity whose size, shape, orientation, or location makes it detrimental to the useful service of the part in which it occurs. It is also a discontinuity or discontinuities which by nature or accumulated effect (e.g., total crack length) render a part or product unable to meet minimum applicable acceptance standards or specifications. This term designates rejectability.
Defect absorption – It refers to the absorption of optical or electro-magnetic wave (EMW) energy by a material because of the localized structural flaws, lattice imperfections, or impurities.
Defect check – It is a structured process of comparing a product, material, or system’s actual state against predetermined design specifications or expected behaviours to identify flaws. Its main goal is to find imperfections before deployment, ensuring structural integrity, safety, and operational reliability.
Defect classification – It is the standardized process of categorizing product or system anomalies based on their severity, origin, and impact on functionality. It systematically identifies ‘why’, ‘where’, and ‘how’ a defect has occurred, ensuring targeted quality control and efficient resource allocation. Defect classification structures analysis around several core parameters, ensuring consistency across design, manufacturing, and software
Defect density – It is the concentration of defects on a wafer, quantified by the number of particles per unit area, which can impact the yield of device manufacturing. Defect density is a key engineering metric which measures the concentration of defects relative to the size or volume of the product.
Defect detection – It is the systematic process of identifying flaws, anomalies, or non-conformities in materials, components, or systems. Its main goal is to ensure structural integrity, prevent failures, and maintain quality control standards.
Defected pipe – It is a pipeline with structural or material irregularities, such as corrosion, cracks, or dents, which weaken its integrity below safety limits. These imperfections compromise the pipe’s ability to withstand internal fluid pressure, potentially leading to leaks or catastrophic failure.
Defect factor – It refers to the specific material characteristics or process parameters which initiate, drive, or influence the formation of structural flaws. It is the root cause behind imperfections in metals, such as impurities, gas porosity, or microstructural abnormalities, which ultimately impact the material’s mechanical integrity
Defect formation energy – It is the energy needed to create a specific crystalline defect (like a vacancy, interstitial, or impurity) in a material. It dictates defect concentration and thermodynamic stability. It is calculated using the total energies of defective and pristine crystal supercells, chemical potentials, and the Fermi level.
Defect image – It is a visual representation which highlights physical flaws, structural irregularities, or manufacturing anomalies on a material’s surface. Extracted through optical, X-ray, or infrared systems, these images are the foundation of automated quality control and computer vision-based inspection.
Defective – It is a quality control term, describing a unit of product or service containing at least one defect, or having several lesser imperfections that, in combination, cause the unit not to fulfill its anticipated function.
Defectivity – It refers to the rate, density, or susceptibility of a system, material, or process to develop flaws. It is a quantifiable metric used in quality control and manufacturing to evaluate reliability, determine yield loss, and measure the number of defects per unit area or volume.
Defect law – It is a normalized relationship which describes the scaling behaviour of defects in turbulent boundary layers under different conditions, including classical outer scaling and specific scaling models.
Defect layer – It is a conceptual or physical region within a material or component which shows a high concentration of flaws, imperfections, or structural anomalies. It is a region within a crystalline material, particularly in ion-implanted silicon, characterized by high concentrations of point defects and defect complexes, typically situated around the mean projected range of the implanted species and extending below the amorphization threshold.
Defect length – It is the physical measurement of a flaw, discontinuity, or imperfection along its longest axis. It dictates structural integrity, where a defect is normally defined by its length, width (or depth), and orientation.
Defect repair – It is an action taken to remedy a product that is nonfunctional or does not match expectations or requirements.
Defects and discontinuities – All defects are discontinuities, but not all discontinuities are defects. A defect is a discontinuity which is severe enough to exceed allowable tolerance limits, making the part unfit for its intended service. A discontinuity is an interruption in the normal physical, metallurgical, or mechanical structure of a material, such as a localized change in density or grain structure.
Defect site – It refers to a localized irregularity or imperfection in a metal’s crystal lattice structure. Defect sites disrupt the orderly arrangement of atoms and dictate a metal’s physical and mechanical properties, such as its strength, ductility, electrical conductivity, and susceptibility to corrosion. These sites refer to irregularities on surfaces, including steps, kinks, grain boundaries, and point defects such as atomic vacancies and substitutions, which serve as active sites for chemisorption and catalytic reactions because of their reduced coordination and unsaturated valences.
Defect size – It is a quantitative metric measuring the dimensions (length, depth, diameter, or volume) of a discontinuity in a material’s structure. It is the critical factor determining whether a metal is going to fail under stress, as larger imperfections act as main stress concentrators and fatigue initiation sites. Defect size classification normally follows established national or international standards to determine part safety and usability.
Defect structure – It is the arrangement of imperfections within a crystal lattice (e.g., atomic vacancies, dislocations, or grain boundaries). These defects dictate material properties like strength, electrical conductivity, and ductility. It also means flaws or faults in a building’s load-bearing elements (like foundations, beams, columns, or slabs). Thees flaws or faults compromise safety and stability and are frequently caused by poor design, sub-par materials, or bad construction practices.
Defect tolerance – It is a material’s ability to maintain its structural integrity and functional properties despite the presence of internal flaws, voids, or microstructural defects. It ensures that a component resists cracking, premature fatigue, or catastrophic failure while in service.
Defect tolerant design – It is frequently referred to as damage-tolerant design. It is an engineering philosophy which assumes microscopic flaws or cracks exist in a material and establishes maintenance protocols and structural limits to ensure the component performs safely without catastrophic failure.
Defense schemes – These schemes refer to proactive strategies designed to improve security in networks by dynamically adjusting to attackers’ methods, hence balancing the rewards of successful data transmission with the costs of security measures. These schemes frequently utilize models from evolutionary game theory to facilitate nodes’ learning and adapt their defense strategies effectively.
Defense structure – It refers to the microscopic arrangement of metals and alloys specifically engineered to absorb impacts, resist extreme temperatures, or stop projectiles. These microstructures, such as quenched and tempered martensite, dictate a material’s ballistic performance and durability.
Defensive design – It is the practice of anticipating all possible ways a user, system, or environment might misuse or stress a product. It involves building safeguards during the design stage to make failure or misuse impossible or to minimize its negative consequences.
Deferrable load – It is an electrical demand which needs a specific quantity of energy but has flexibility in ‘when’ it is powered. As long as the energy is delivered within a defined time window or storage threshold, exact timing is not critical, allowing it to adapt to renewable generation or off-peak pricing.
Deferred maintenance – It is a set of corrective maintenance activities which are not immediately initiated after the occurrence of a failure but are delayed in such a way which does not affect the production process.
Deferred production – It is the volume of output (such as manufactured goods) which is delayed or postponed because of the planned maintenance, equipment failure, or operational constraints. Also known as production deferral, it represents a temporary loss of revenue, though the product remains in the ground or pending completion. This concept is highly critical for monitoring plant health and scheduling downtime.
Deficit air – It normally refers to a combustion environment or pneumatic control system where the actual quantity of air supplied is less than the theoretical (stoichiometric) requirement needed for complete combustion or mechanical operation.
Define – It is the phase in the portfolio life cycle in which projects, programmes, and any organizational changes needed to realize strategic objectives are identified and examined.
Define, measure, analyze, improve, and control (DMAIC) process – It is a structured, data-driven process improvement methodology used to improve existing processes and reduce variation. It is a core component of six sigma. It provides a systematic approach to identify, understand, and address problems, ultimately leading to improved efficiency and customer satisfaction.
Define, measure, analyze, design, and verify (DMADV) process – It is a data-driven quality strategy that focuses on the development of new products or services compared to existing ones. The define, measure, analyze, design, and verify method or approach is frequently used when implementing new strategies because of its basis in data, its ability to identify success early, and its method, which requires thorough analysis. Like define, measure, analyze, improve, and control (DMAIC), it is an integral part of a six-sigma quality initiative.
Define (X-rays) – It is to limit a beam of X-rays by passage through apertures to obtain a parallel, divergent, or convergent beam.
Defining equation – It refers to an equation used to define a model, such as ordinary differential equations or algebraic equations, to perform simulations. It is a key component in minimizing user effort to implement, run, and analyze models in a computational environment.
Definite function – It is a scalar function whose outputs follow strict positivity or negativity constraints. These functions are fundamental in advanced calculus, optimization, and control theory to determine minima and system stability, or in harmonic analysis.
Definition – it is the clarity or sharpness of a microscopic image. Definition is also the formal, universally agreed-upon explanation of what a term represents. Definitions can be classified into two large categories namely intensional definitions (which try to give the sense of a term), and extensional definitions (which try to list the objects that a term describes). Another important category of definitions is the class of ostensive definitions, which convey the meaning of a term by pointing out examples. A term can have several different senses and multiple meanings, and hence need multiple definitions.
Definitive criterion – It is a final, authoritative standard used to judge, evaluate, or reach a conclusive decision. It combines two concepts namely a criterion (a rule or benchmark for assessment) and definitive (conclusive, fixed, and exhaustive).
Definitive estimate – A definitive estimate reaches a total project cost estimate by computing cost estimates for all a project’s work packages. Definitive estimating is considered a highly accurate estimation technique, with estimates falling within a ten-percent range of the actual budget.
Deflagration – It is a rapid combustion process where a flame propagates through a substance or mixture at a speed slower than the speed of sound. This type of explosion is subsonic and normally less intense than a detonation, but can still be violent and destructive.
Deflagration process – It is a mode of exothermal reaction where the velocity of propagation of the reaction zone is much lower than the velocity of sound in the material, with the direction of flow of the reaction products opposite to that of the reaction wave, as seen in the burning of gunpowder or rocket propellant.
Deflash – It is the process of removing excess material (flash) from the parting line of a moulded rubber product.
Deflashing – It is a finishing technique used to remove the flash (excess, unwanted material) on a plastic moulding.
Deflection – In metal-forming and forging, it is the quantity of deviation from a straight line or plane when a force is applied to a press member. Normally it is used to specify the allowable bending of the bed, slide, or frame at rated capacity with a load of pre-determined distribution.
Deflection characteristic – It describes how a material, structure, or component bends, shifts, or changes shape in response to an applied force, load, or environmental stress. It plots or defines the relationship between the applied force and the resulting physical displacement.
Deflection coil – It is an electro-magnetic component used in cathode-ray tubes (CRTs) to steer and focus an electron beam. Placed around the neck of the tube, it generates horizontal and vertical magnetic fields which sweep the electron beam rapidly across the screen to form visual images.
Deflection curve – It is a mathematical representation of how a structural element, like a beam or column, bends and deforms under an applied load. It plots the physical displacement of the element’s central axis along its length.
Deflection drum – It is a drum which is strategically employed to redirect the conveyor belt, necessitating occasional inspections for wear, alignment, and seamless operation.
Deflection equations – These equations define the mathematical relationship between physical loads and the resulting curvature of a structural element (like a beam). Deflection equation is a mathematical formula used to calculate how much a structural element bends or deforms when subjected to an external load. It ensures that buildings and machines remain safe and functional.
Deflection factor – It describes the degree to which a structural element (such as beam) is deformed, bend or displaces laterally (in the direction transverse to its longitudinal axis) under a load. It is a measure of the deformation of a structure or element, typically expressed as the displacement of a point on the element or the angle of rotation of a section.
Deflection formulas – These formulas evaluate how much a structural member is going to bend, ensuring a structure remains safe and functional without sagging or cracking.
Deflection function – It is the mathematical or geometric representation of how much a structure (like a beam) displaces from its original position under load. It typically calculates the displacement distance as a function of position, x, along the member.
Deflection methods – These methods refer to the mathematical and analytical techniques used to calculate the physical displacement (bending or shifting) of a structural element from its original position when subjected to external loads. These calculations are important to ensure structures and machine parts remain safe and serviceable.
Deflection of Almen strip – It is also known as arc height. It is the convex curvature a standardized metal strip takes after being subjected to shot peening or similar surface treatments. It serves as the main metric to quantify and control the intensity and energy of a shot peening process.
Deflection plate – It is a component used to guide or redirect the path of particles, beams, or fluids. In oscilloscopes, it typically refers to electrostatic plates which steer electron beams or structural barriers in mechanical systems which direct gas or liquid flow.
Deflection speed – It refers to the rate at which an object or material deforms (bends or displaces) when a load or force is applied to it. It is normally measured during physical testing to determine a material’s structural integrity or stiffness.
Deflection, structural – It is the temporary or permanent displacement or bending of a structural element (like a beam, column, or slab) from its original, unloaded position. It occurs when the structure is subjected to external loads, such as gravity, wind, or earthquakes, or its own weight. Structural deflection is measured as either a linear distance (e.g., millimeters or inches) or as an angular rotation (e.g., in radians).
Deflection temperature under load – It is the temperature at which a simple cantilever beam deflects a given amount under load. It was earlier called heat distortion temperature.
Deflection, tool – Tool deflection is the displacement of the tool because of the balance between the restoring force from the tool’s stiffness and the cutting forces acting during machining, considerably influencing the compliance of the machine-tool-workpiece system. It typically results in expected deflections of 2 micrometers to 5 micrometers for tools of similar sizes and materials.
Deflection yoke – It is an electro-magnetic assembly placed around the neck of a cathode-ray tube (CRT), typically found in older televisions and monitors. It uses controlled magnetic fields to bend and direct the electron beam horizontally and vertically, allowing it to systematically scan the screen and create an image.
Deflection zone – it is a spatial buffer designed to safely absorb the kinetic energy of an impacting vehicle, or a fluid mechanics region where a flowing stream is forced to deviate from its original path.
Deflector – It is a flat or angle like section placed longitudinally over the conveyor making an angle (can be adjustable or fixed) with the conveyor axis. This acts as an obstruction to the movement of the load and deflects them to one side of the conveyor axis.
Deflocculant – It is also called deflocculating agent. It is an electrolyte which is added to a material to produce dispersion of fine particles.
Deflocculated castable – It is a refractory castable with a hydraulic bond, with a minimum of 2 % by weight of ultra-fine particles (less than one micrometer) and at least one deflocculating agent.
Deflocculating – It is thinning the consistency of a slip by adding a suitable electrolyte.
Deflocculation – It is a state of colloidal suspension in which the individual particles are separate from one another, this condition being maintained by the attraction of the particles for the dispersing medium (for example, hydration) or by the assumption of like electrical charges by the particles, hence resulting in their mutual repulsion, or both.
Defocus blur – It is the optical effect in which objects located in front of or behind the camera’s precise focal plane appear soft, indistinct, or unsharp. It happens since light rays from these out-of-focus objects do not converge perfectly on the image sensor, instead spreading out to form a ‘circle of confusion’.
Deforestation – It is the removal and destruction of a forest or stand of trees from land that is then converted to non-forest use. Deforestation results in habitat destruction which in turn leads to bio-diversity loss. Deforestation also leads to extinction of animals and plants, changes to the local climate, and displacement of indigenous people who live in forests. Deforested regions also frequently suffer from other environmental problems such as desertification and soil erosion. Another problem is that deforestation reduces the uptake of carbon di-oxide from the atmosphere.
Deformability – In tribology, it is that quality of a plain bearing material which allows it to adjust itself to shaft deflections and minor misalignments by deformation or by wearing away of bearing material without producing operating difficulties.
Deformable body – It is a physical object which changes its size, shape, or volume when subjected to external forces. Unlike an idealized ‘rigid body’ which remains completely stiff, a deformable body stretches, compresses, or bends, creating internal resistance, stress, and strain.
Deformable contours – These are computer-generated curves which automatically adjust their shape to outline object boundaries in an image. They are driven by an energy-minimizing algorithm which balances internal forces (like smoothness and elasticity) with external forces (like image edges and gradients).
Deformable model – It is a technique which defines geometric shapes capable of altering their form over time. Instead of relying on static, rigid templates, these models simulate real-world physical or statistical behaviours, allowing them to stretch, bend, and adapt to match specific data in images or 3D spaces. Deformable models broadly bridge three disciplines namely geometry (to define the shape), physics or probability (to dictate how the shape behaves), and approximation theory (to fit the model to data).
Deformation – It is a change in the form of a body because of the stress, thermal change, change in moisture, or other causes. It is measured in units of length.
Deformation bands – These are the parts of a crystal which have rotated differently during deformation to produce bands of varied orientation without individual grains.
Deformation behaviour – It describes how a material changes shape or size in response to applied forces. It is categorized into elastic deformation (which is fully reversible) and plastic deformation (which causes permanent structural changes). This mechanical response is critical for structural engineering, and materials science.
Deformation characteristic – It defines how a material, structure, or geological mass changes its shape, volume, or size when subjected to an external force, stress, or time-dependent environmental conditions. Understanding these characteristics is important to predict how things are going to behave under load.
Deformation condition – It refers to the physical circumstances and variables that dictate how a material alters its shape or size when subjected to an external force. It involves collective environmental factors and applied forces such as temperature, strain rate, stress state, and material composition that govern how and if an object yields.
Deformation control – It refers to the management of how an object’s shape or dimensions change under load. It is a concept used in different applications, from structural engineering to manufacturing, where minimizing unwanted changes in shape or size is crucial. Deformation control frequently involves techniques like heat treatment, clamping, and optimizing machining processes to reduce distortions.
Deformation curve – It is also called load-deformation curve. It is a graph in which corresponding values of stress and strain are plotted against each other. Values of stress are normally plotted vertically (ordinates or y-axis) and values of strain horizontally (abscissas or x-axis). It is a fundamental tool used to determine a material’s stiffness, elasticity, yield point, and ultimate strength.
Deformation damage – It refers to a definitive degradation of materials which occurs through processes such as nucleation of cavities or micro-cracks, growth, and coalescence, distinguishing it from reversible deformations described in continuum mechanics. This damage is characterized by a drop in the elastic modulus during unloading, indicating a loss of material integrity.
Deformation degree – It is the quantitative measure of shape or size change a material undergoes when subjected to an external force. It describes the ratio of dimensional change (such as elongation or compression) relative to the original dimensions, helping to calculate material strength and structural integrity.
Deformation energy – It is a measure of the energy absorption characteristics of a material determined by measuring the area under the stress-strain diagram.
Deformation energy methods – In these methods, the total work of extrusion is equated to the homogeneous work of deformation.
Deformation field – It is a mathematical or spatial mapping which describes how every point in a continuous body or object changes its position, shape, or size from an initial, undeformed state to a final state. It basically quantifies the movement of material points through a coordinate system.
Deformation flow – it describes the continuous, permanent change in shape or size of a solid material when subjected to a persistent mechanical force which exceeds its elastic limit. It typically encompasses plastic deformation, where materials undergo internal structural rearrangement in processes like rolling, forging, or extrusion.
Deformation function – It maps the initial position of points in a continuous body to their displaced positions in space. It describes how a material or shape stretches, twists, or compresses over time. This concept is widely used across mechanics, geometry processing, and computer graphics.
Deformation gradient – It is a second-order tensor which measures the local deformation of a material. It mathematically maps the coordinates of an infinitesimal line segment from its original reference state to its current, deformed state. In continuum mechanics, the deformation gradient is the spatial derivative of the mapping function which tracks a material particle’s motion.
Deformation gradient tensor – It is a fundamental mathematical tool in continuum mechanics used to map the position of a material point from its undeformed (reference) configuration to its deformed (current) configuration. It characterizes local stretching, shearing, and rotation around that point. Deformation gradient tensor is a second-order tensor which relates the position of points in a deformed state to their positions in the undeformed state, represented by the equation. It describes the change in configuration because of the deformation and is important for analyzing material behaviour under loading conditions.
Deformation grains – refer to the microstructural changes that occur when a metal undergoes permanent (plastic) deformation. As external stress is applied, the metal’s crystalline structure changes. Grains elongate, dislocations multiply, and boundaries shift, drastically altering the metal’s strength and ductility.
Deformation heating – It is also called deformation-induced heating. It is the phenomenon where the mechanical work applied to a metal during plastic deformation is converted into heat. When a metal is shaped (e.g., through forging or rolling), the energy needed to move internal structural defects translates directly into a noticeable, and sometimes drastic, rise in the material’s temperature.
Deformation-induced surface roughening – It is an intrinsic material phenomenon where the initially smooth, free surface of a solid (typically poly-crystalline metal) develops irregular undulations, peaks, and valleys as it undergoes plastic deformation, even in the absence of external surface forces like mechanical contact or corrosion.
Deformation-induced transformation – It is a phenomenon where a mechanical force (stress or strain) triggers a phase change in a material’s crystal structure. It is a solid-state phase change triggered by mechanical force (stress or strain) rather than just temperature. Very frequently observed in metastable alloys (like austenitic stainless steels and titanium alloys), this phenomenon fundamentally alters the material’s structural properties. This considerably improves a material’s ductility and work-hardening capacity.
Deformation invariant – It is a mathematical or physical property which remains unchanged when an object or system undergoes a specific geometric transformation, such as stretching, bending, or twisting. These properties allow scientists to identify and analyze systems irrespective of their physical distortion.
Deformation law – It refers to the mathematical relationships which describe how materials change shape or volume under stress, typically expressed as a sum of spherical and deviatoric components representing volumetric and distortion changes, respectively.
Deformation limit – In drawing, It is the limit of deformation which is reached when the load needed to deform the flange becomes higher than the load-carrying capacity of the cup wall. The deformation limit (limiting drawing ratio, LDR) is defined as the ratio of the maximum blank diameter which can be drawn into a cup without failure, to the diameter of the punch.
Deformation lines – These are thin bands or lines produced by cold working in grains of some metals, particularly those of face centered cubic structure. They are not removed by repolishing and re-etching.
Deformation locking – It normally refers to a mechanism where dislocations (the tiny defects in a metal’s crystal lattice responsible for plastic deformation) become physically obstructed or trapped. When these atomic imperfections are immobilized, the metal becomes much harder and less prone to further shape changes. This locking behaviour is the fundamental reason metals get stronger when subjected to mechanical forces.
Deformation mapping – It is more formally known as deformation-mechanism mapping. It refers to graphical diagrams which visually summarize the dominant physical processes (such as dislocation glide, diffusion, or grain boundary sliding) which alter the shape and structure of a metal under varying conditions of stress and temperature. These maps are important tools in materials science and engineering. They help to map out exactly how a metal behaves under specific operating conditions.
Deformation mechanism – It is a physical or atomic process by which a metal changes shape or size under mechanical force. It dictates how a material responds to applied stress, either temporarily (elastic) or permanently (plastic), and governs the metal’s strength, formability, and durability. The exact mechanism of shape change largely depends on the crystal structure of the metal, the temperature, and the magnitude of the applied load.
Deformation mode – It refers to the distinct physical mechanism, either elastic or plastic, by which a metal changes shape or size under applied forces. Elastic deformation is temporary and fully recoverable, while plastic deformation creates permanent changes in the metal’s internal crystal structure.
Deformation model – It is a mathematical or physical framework used to quantify and predict how an object, material, or surface changes its size, shape, and position when subjected to external forces or stress. It tracks internal strain and spatial displacement from a reference configuration.
Deformation modelling – It is the use of mathematical and computational methods to simulate, predict, and optimize how a metal changes shape and internal structure under mechanical force and heat. It bridges the gap between raw material and a finished, high-performance part.
Deformation modes – These refer to the fundamental ways a metal changes its shape or size under applied forces (stresses). The two main classifications are elastic deformation (reversible change) and plastic deformation (permanent change). The three principal modes by which systems undergo deformation are tensile or extensional deformation, shear deformation, and bulk or hydrostatic deformation.
Deformation of structures – It refers to the change in shape or displacement of structural elements under external loads, which can be measured using techniques such as 3D laser scanning or photogrammetry. This includes vertical and horizontal deflections caused by static and dynamic loads, as evidenced by different experimental methods and models.
Deformation plasticity – It is a solid material’s ability to undergo an irreversible, permanent change in shape when subjected to external forces which exceed its elastic limit. Unlike elastic deformation, which snaps back when the load is removed, deformation plasticity results in lasting structural and microstructural changes.
Deformation process – It is a method which uses irreversible deformation to permanently change the shape of ductile work-pieces while obtaining desired microstructures and material properties. These processes operate within the elastic–plastic regime of the stress–strain curve and include techniques such as rolling, forging, extrusion, and bending.
Deformation-processed discontinuously reinforced aluminum alloys – These are metal-matrix composites where a ductile aluminum alloy is combined with a discrete, discontinuous ceramic reinforcement like SiC (silicon carbide) particles or whiskers. Unlike continuous composites, these discontinuously reinforced aluminum (DRA) materials can be heavily shaped using standard thermo-mechanical deformation techniques like forging, extrusion, and rolling.
Deformation processes – These are manufacturing methods which use mechanical force to permanently alter the shape of a metal work-piece without adding or removing material. These processes transform solid materials from one shape into another. By stressing the metal past its yield point, the material is plastically deformed to achieve a desired geometry, improved structural properties, or refined microstructure. The initial shape is normally simple (e.g., a billet or sheet blank) and is plastically deformed between tools, or dies, to get the desired final geometry and tolerances with needed properties.
Deformation processing – It is a class of manufacturing operation which involves changing the shape of a work-piece by plastic deformation through the application of a compressive force. It is frequently carried out at high temperature.
Deformation property – It refers to how a material’s shape, volume, or size changes when subjected to external forces or stress. These properties determine whether a material will stretch, bend, or permanently alter its form under physical pressure, and are foundational to structural and mechanical design.
Deformation rate – It is frequently called strain rate. It is the speed at which a metal changes shape or dimensions under an applied load. Mathematically defined as the rate of change of strain over time, it determines how a metal responds to processes like forging, rolling, or high-temperature stress.
Deformation ratio – It is a dimensionless metric used to quantify shape changes in an object under external forces.
Deformation, recovery, and recrystallization – These are the three stages which form the sequential steps of metal softening and microstructural restoration (frequently part of annealing cycles). Deformation changes a metal’s shape and increases its strength through cold work, which creates internal stress. Recovery is the initial heating phase where internal stresses are reduced by rearranging and annihilating atomic defects without forming new grain boundaries. Recrystallization replaces the deformed grains with new, defect-free grains.
Deformation resistance – It is a material’s ability to withstand changes in shape or size when subjected to external forces. Measured by properties like stiffness (elastic resistance) and strength (plastic resistance), it determines how much stress a material can absorb before bending, stretching, or permanently failing.
Deformation response – It refers to how a material, structure, or geological formation changes in shape, size, or volume when subjected to an external load, force, or stress. It describes the relationship between the applied force and the resulting structural alteration, which is typically measured as strain. The deformation response of a material is normally evaluated across several distinct phases, depending on the magnitude of the applied stress.
Deformation state – It describes the specific size, shape, and orientation of a body after it has been subjected to external forces. It is typically evaluated by measuring strain (the relative change in dimensions) and stress (the internal forces causing the change) compared to its original, unloaded reference state.
Deformation structure – It refers to the microscopic or macroscopic changes in a material’s shape, volume, or geometry induced by external forces. It involves internal microstructural changes, such as the movement of dislocations and the evolution of sub-grains. Understanding deformation structures provides critical insights into how different materials respond to stress.
Deformation temperature – It is the specific temperature at which a metal is permanently shaped (like rolling, forging, or bending). It dictates the flow stress, and whether the process is classified as cold, warm, or hot working. Deformation temperature affects the overall microstructure evolution, including inter-metallic compounds (IMCs) formations, grain size, dissolution, and precipitates’ coarsening at different zones.
Deformation tensor – It is a mathematical matrix which describes how a solid or fluid body changes shape, size, and orientation when subjected to external forces. It quantifies the relative displacement between neighbouring particles in a continuous medium. In continuum mechanics, the main deformation tensor is the deformation gradient tensor.
Deformation testing – It measures how a material, sand mould, or cast metal sample changes shape, bends, or resists permanent distortion under mechanical or thermal stress. It evaluates either the physical formability of the final cast metal or the stability of moulds and cores during pouring.
Deformation texture – It is the preferred, non-random orientation of crystal grains which develops in a metal when it undergoes plastic deformation (such as rolling, drawing, or extruding). As the material is stressed, individual grains rotate and align their internal slip planes with the applied force, causing the material to become anisotropic (having direction-dependent properties).
Deformation texture modelling – It is a computational method used to predict how the microscopic crystals (grains) inside a metal rotate and align during plastic deformation (such as rolling, forging, or drawing). Since most engineering metals are poly-crystalline (made of countless tiny crystals), mechanical forces cause these grains to rotate towards specific orientations. This ordered pattern is known as a crystallographic texture. Predicting this texture is important since aligned grains make the metal anisotropic (meaning its strength, formability, and magnetic properties vary depending on the direction).
Deformation theory – It studies how geometric structures or solutions to mathematical problems change when subjected to small variations, or deformations. It provides a rigorous framework for understanding how a specific state or solution behaves under slight perturbations.
Deformation theory of plasticity – It is a simplified continuum mechanics approach which relates total strains directly to total stresses using a secant modulus. It assumes that the state of strain in a material depends only on the final state of stress, making it mathematically similar to non-linear elasticity and ignoring the actual loading history.
Deformation twin – It is a twin formed in a crystal by simple shear and / or simple shear plus shuffle movements under external loading.
Deformation twinning – It is a plastic deformation mechanism where a portion of the crystal lattice deforms by undergoing a uniform shear. This reorients the atoms to form a perfect mirror image of the parent crystal structure across a specific plane (the twin plane).
Deformation twins – These are crystallographic regions where atoms shift in a cooperative, shear movement to form a mirror image of the parent crystal lattice. They are important for accommodating extreme strain, controlling work-hardening, and altering the mechanical properties of materials.
Deformation under load – It is the dimensional change of a material under load for a specified time following the instantaneous elastic deformation caused by the initial application of the load.
Deformation wear – It is the sliding wear involving plastic deformation of the wearing surface. It is a process where surfaces undergo permanent (plastic) deformation rather than just elastic shape changes or brittle fractures. It happens when localized contact stresses exceed the material’s yield strength, causing surface metals to smear, bulge, or form wear debris.
Deformation zone – It a region where materials experience significant stretching, shearing, or other forms of deformation, frequently caused by opposing forces or flows. In geology, it refers to an area with extensive fracturing and faulting, while in the atmosphere, it is a region where air masses change shape due to converging flows. In metal forming, it is the area where the material undergoes plastic deformation during shaping.
Deformed configuration – It refers to the final, altered geometry of a body after it has been subjected to external forces. It contrasts directly with the initial, stress-free state (the undeformed configuration) and accounts for both rigid-body movements and internal strain. Understanding the relationship between the initial reference state and the deformed configuration is important for calculating stress, strain, and predicting material failure.
Deformed grains – These refer to the microstructural changes which occur when a metal is permanently shaped (e.g., rolled, forged, or drawn) through plastic deformation. This process alters the original crystalline structure by physically elongating the grains and multiplying internal defects called dislocations, resulting in dramatically increased hardness but reduced ductility.
Deformed material – It refers to metal which has undergone a change in size or shape because of the mechanical forces. This happens either temporarily (bouncing back once stress is removed) or permanently (permanently altering the internal grain structure). The deformation process involves two main stages (elastic deformation and plastic deformation) and several mechanical outcomes.
Deformed micro-structure – It refers to the altered internal arrangement, defects, and crystalline lattice structure of a material after it has undergone permanent (plastic) deformation. It is characterized by elongated grains, tangled dislocations, and high stored internal energy which alter the material’s mechanical properties.
Deformed shape – it refers to the altered configuration of a physical object or structural model after it has been subjected to external forces, loads, or stresses. It contrasts with the initial, unforced ‘undeformed shape’ and represents how the body’s geometry, such as its length, volume, or angles, has changed.
Deformed state – It is also called deformed microstructure. It refers to the altered physical shape and internal crystal structure of a metal after it undergoes plastic deformation (permanent changes exceeding its elastic limit).
Deforming process – It is a manufacturing method which transforms shapes and / or dimensions of materials without changes in mass or composition, typically through permanent plastic deformation under controlled conditions of temperature, stress, and strain.
Deform, material – Material deformation refers to the change in size and shape of a material when subjected to external loads, which can be classified into elastic deformations, where the material returns to its original shape, and plastic deformations, which result in permanent alterations because of the changes in the material’s micro-structure.
Defuzzification – It is the final step in a fuzzy logic system, where the system converts a calculated ‘fuzzy’ output (a range of possibilities) into a single, exact numerical value (a ‘crisp’ number) which a physical system or computer can actually act upon.
Degasification – It is the process of removing contaminants like hydrocarbons from a sample to prevent interference with adsorption systems and analyses in chemistry. It involves cleaning the sample and ensuring a clean surface to avoid issues like blockages and desorption during analysis.
Degasifier – It is a substance which can be added to molten metal to remove soluble gases which can be otherwise occluded or entrapped in the metal during solidification.
Degasser – It is a device used to remove dissolved and entrained gases from a liquid. By eliminating unwanted air bubbles or volatile gases, it ensures the accuracy of precision instruments, maintains fluid density, or prevents dangerous pressure buildups.
Degassing – It is a chemical reaction resulting from a compound added to molten metal for removing gases from the metal. Inert gases are frequently used in this operation. It is also a fluxing procedure used for aluminum alloys in which nitrogen, chlorine, chlorine and nitrogen, and chlorine and argon are bubbled up through the metal to remove dissolved hydrogen gases and oxides from the alloy.
Degassing, chemical – Chemical degassing is the extraction or neutralization of trapped vapours, dissolved gases, or volatile compounds from liquids, solids, or industrial vessels. It is achieved by injecting reactive chemicals (like oxygen scavengers), applying physical vacuums / heat, or using specialized cleaning surfactants to prevent safety hazards, corrosion, and reaction interference.
Degassing flux – It is a specialized chemical powder, tablet, or granular mixture used in metal casting (particularly for aluminum alloys) to remove dissolved hydrogen gas and non-metallic solid inclusions from the molten metal before pouring.
Degassing tank – It is a vessel used to remove unwanted, dissolved, or hazardous gases from liquids. Depending on the industry, it is utilized to extract dangerous vapours from petroleum equipment before maintenance, purge trapped air from cooling systems, or clear oxygen from boiler water.
Degaussing – It is the process of decreasing or eliminating a remnant magnetic field. Because of the magnetic hysteresis, it is normally not possible to reduce a magnetic field completely to zero, so degaussing typically induces a very small known field referred to as bias. Degaussing is also used to reduce magnetic fields in cathode ray tube monitors and to destroy data held on magnetic storage.
Degenerate channels – These refer to a scenario in communication systems where the spatial correlation among transmitted signals limits the achievable throughput, resulting in poorer performance in terms of simultaneously transmitted streams.
Degenerative chain transfer – It is a polymer chemistry reaction where an active growing chain’s radical transfers to a dormant transfer agent. Since the newly formed active chain and the dormant species have identical reactivity, the process repeats continuously without changing the overall reaction kinetics. This dynamic exchange allows for the creation of polymers with highly controlled lengths and narrow molecular weight distributions.
Degenerative iodine transfer – It is very frequently known as iodine transfer polymerization (ITP). It is a controlled radical polymerization technique. It relies on the exchange of an iodine atom between an active growing polymer chain and a dormant one, ensuring all chains grow evenly and yield polymers with a uniform length.
Degradable materials -These are substances designed to break down into smaller particles over time through chemical, thermal, or biological processes. While the terms are frequently used inter-changeably, degradable items differ from bio-degradable ones. True bio-degradation relies entirely on micro-organisms like bacteria and fungi to safely convert waste into natural elements like water, bio-mass, and carbon di-oxide.
Degradable polymers – These are materials engineered to break-down over time through chemical, physical, or biological processes, resulting in a substantial loss of their original physical properties. This break-down ensures they do not persist in the environment or the human body, preventing waste accumulation or toxicity.
Degradable polyurethane – It is a specialized class of polymer designed to decompose into harmless by-products, frequently by microbial activity (bio-degradable) or targeted chemical triggers. It is synthesized using bio-based raw materials (e.g., algae, castor oil) to prevent toxic micro-plastic buildup.
Degradation – It is a deleterious change in the chemical structure, physical properties, or appearance of a material.
Degradation agent – It is an environmental factor, substance, or organism which causes the physical, chemical, or biological breakdown of a material. These agents determine the life-span, durability, and stability of materials.
Degradation equation – It is a mathematical model used to quantify the rate at which a system, material, or substance deteriorates over time. It can describe physical wear, chemical break-down, environmental decay, or digital image blur.
Degradation kinetics – It is the quantitative study of the rate and pathways by which a substance or material breaks down over time. It models factors like temperature, pH, and moisture using reaction orders and rate constants to predict stability, shelf life, and breakdown mechanisms.
Degradation mechanism – It is the specific physical, chemical, or mechanical process responsible for the progressive deterioration of equipment, materials, or systems during service. Identifying these processes, such as corrosion, fatigue, or thermal breakdown allows engineers to predict deterioration and implement preventive maintenance.
Degradation model – It is a mathematical framework used to describe and predict how systems, materials, or digital data lose quality, performance, or structural integrity over time. These models are mainly used in reliability engineering (to forecast component life-spans) and digital signal processing (to analyze and reverse image / audio blur).
Degradation pathway – It is a sequential series of chemical, biological, or physical reactions which break-down complex molecules into simpler compounds or waste products. It details the exact sequence of transformations, intermediates, and enzymes involved in breaking down substances such as environmental pollutants.
Degradation process – It is the gradual, frequently predictable decline in an asset’s efficiency, output, or structural integrity over time. It is driven by environmental exposure, mechanical stress, or normal wear and tear, and serves as a precursor to eventual functional failure. Understanding these processes is important for preventing unexpected failures and minimizing maintenance costs.
Degradation product – It is any unwanted substance, material, or compound formed when a system, material, or product breaks down. These by-products are caused by chemical, physical, or thermal alterations triggered by environmental factors like temperature, moisture, radiation, or mechanical stress.
Degradation rate – It is the speed at which a material, component, or system loses its functional performance, efficiency, or structural integrity over time. It is typically calculated as the percentage of decline per year or as a physical measurement of material lost per unit of time (e.g., millimeters per year).
Degradation, system – System degradation refers to the reduction in a system’s actual performance because of the irreversible physical or chemical alterations, frequently aggravated by environmental conditions and usage rates. This phenomenon is particularly notable in energy storage technologies, where it leads to rapid deterioration and necessitates early replacement before the expected service life.
Degradation time – It is the duration it takes for a material, component, or system to deteriorate to a predefined failure threshold under specific environmental and operational conditions. It is a core metric for predicting remaining useful life (RUL) and preventing unplanned system downtime.
Degraded image – It is a digital image whose quality, clarity, or informational value has been compromised by noise, blur, or other distortions during acquisition, transmission, or processing. Engineering fields use mathematical models to define, analyze, and reverse these imperfections to recover the original scene.
Degraded material – It is one whose physical, chemical, or mechanical properties have deteriorated over time. This loss of integrity is caused by environmental factors (e.g., ultra-violet radiation, moisture) or operational stresses (e.g., friction, cyclic loading) and directly impacts a product’s longevity and safety.
Degrading effect – It is the gradual, frequently irreversible deterioration of a material, component, or system’s performance over time. It is driven by operational wear, fatigue, or harsh environmental conditions (e.g., thermal stress, chemical corrosion, or ultra-violet radiation), leading to a decline in efficiency, load capacity, or safety.
Degrading polymer – It is a polymer which undergoes changes in its properties because of the biological, chemical, or physical reactions, leading to the breaking of bonds and further chemical transformations, ultimately influencing its mechanical, electrical, or optical characteristics.
Degreasing – It is the removal of grease and oils from a surface. It can be accomplished by immersion in liquid organic solvent, by solvent vapours condensing on the parts being cleaned (vapour degreasing), or by spraying the parts with solvent.
Degree – It is a measure of level, intensity, or extent. In case of angle, a degree is a unit of measurement for angles, equal to 1/360 of a full rotation. In case of temperature, a degree is a standardized unit of measurement used to express how hot or cold a substance or environment is, normally measured using the Celsius, Fahrenheit, or Kelvin scales.
Degree equation – It refers to an algebraic equation which can be expressed as a polynomial of ‘nth’ degree, which normally has ‘n’ roots, some of which can be imaginary or equal.
Degree of alignment – It defines the extent to which a material’s internal microscopic structures (such as crystals, grains, or fibres) are oriented in a specific, uniform direction. A higher degree of alignment results in strong anisotropic properties, meaning the material performs differently depending on the direction of applied forces or magnetic fields.
Degree of anisotropy – It is a quantitative metric measuring how much a material’s physical or mechanical properties (like strength, elasticity, or conductivity) vary depending on the direction of measurement. A degree of zero indicates complete isotropy (properties are the same in all directions), while higher values indicate increasing directional dependency.
Degree of carbonization – It defines how far raw organic materials (like coal) have been converted into solid carbon residue (coke) through thermal decomposition. It is mainly dictated by the maximum pyrolysis temperature and heating duration in an oxygen-free environment. A higher degree of carbonization indicates the removal of more volatile elements (hydrogen, oxygen, nitrogen) and a higher fixed-carbon percentage in the resulting solid.
Degree of control – It refers to the extent to which a system can be regulated or managed to achieve a desired outcome. It encompasses the level of precision, accuracy, and flexibility in controlling a process or system’s variables.
Degree of conversion – It measures the fraction of a reactant or phase which has undergone a chemical or physical transformation. Ranging from 0 (no reaction) to 1 (complete transformation), it is used to quantify smelting processes, polymerization, or solid-state phase changes. It represents the extent to which the reaction has advanced. In extractive metallurgy, this is frequently expressed as ‘degree of conversion = moles of reactant consumed / initial moles of reactant fed’. It is widely evaluated using thermal analysis techniques like thermogravimetry (TGA) and differential scanning calorimetry (DSC) to monitor reduction or oxidation reactions.
Degree of dissociation – It is the fraction of original molecules (or compounds) which split into simpler molecules, atoms, or ions at a given temperature and pressure. It is a unitless value ranging from ‘0’ (no dissociation) to ‘1’ (complete dissociation), and is mathematically defined as ‘degree of dissociation = moles of compound dissociated / initial total moles of compound.
Degree of freedom – It is a technical term reflecting the number of independent elements comprising a statistical measure. Certain distributions need a degree of freedom values to fully characterize them. It is the number of ways a value can differ from others – one less than the total number of in a sample (n -1). Degrees of freedom is also the number of independent variables (such as temperature, pressure, or concentration within the phases present) which can be altered at will without causing a phase change in an alloy system at equilibrium, or it is the number of such variables which are to be fixed arbitrarily to define the system completely.
Degree of incline – It is the angle at which a conveyor system slopes upward, demanding precise adjustments and regular checks.
Degree of polymerization – It is the number of structural units, or mers, in the average polymer molecule in a sample measure of molecular weight.
Degree of ramming – It defines the extent of compaction or density achieved when packing moulding sand around a pattern. It is measured as the ratio of the volume of the compacted sand to the volume of the uncompacted sand. Proper ramming ensures the sand mold is strong enough to withstand the pressure of molten metal. However, it is to be carefully controlled to balance important properties.
Degree of saturation – It is a dimensionless value. It is the ratio of the volume of water in a material (like soil) to the total volume of its empty spaces (voids). It is typically expressed as a percentage, where 0 % indicates perfectly dry soil and 100 % indicates all voids are completely filled with water. For cast iron, it is used to indicate how close its chemical composition is to the eutectic composition. It determines whether the iron is hypoeutectic, eutectic, or hypereutectic, which heavily influences its melting point, fluidity, and final microstructure.
Degree of sensitization – It is a quantifiable measure of a metal’s susceptibility to inter-granular corrosion (IGC) and inter-granular stress corrosion cracking (IGSCC). It indicates the extent to which grain boundaries have become chemically vulnerable because of the depletion of corrosion-resistant elements (like chromium or magnesium) caused by heat exposure.
Degree rotation – It is the measurement of an angle in degrees which an object, part, or vector turns around a fixed central point or axis. It defines angular position and orientation in mechanical design, structural analysis, and motion control. In additive manufacturing, degree rotation refers to the adjustment of the angle between scan vectors, which can optimize the micro-structure and mechanical properties of fabricated components. Specifically, different degrees of rotation, such as 90-degree, influence the temperature gradient and residual stresses, leading to variations in the mechanical performance of the materials.
Degumming – It is the chemical or physical process of removing phospholipids, gums, and trace metals from natural fibres. The main methods used to achieve this include water degumming, acid degumming, and enzymatic degumming.
Dehumidification – It is the process of removing water vapour from a gas or air stream to lower its humidity or dew point. The two main techniques used are cooling (refrigerative) condensation and chemical (desiccant) adsorption. It is the controlled removal of water vapour from process air or gas streams, specifically targeting blast air for furnaces, moulds / raw materials, and heat-treatment atmospheres.
Dehumidification technology – It refers to the mechanical, chemical, or physical methods used to extract water vapour from gas or air streams, mainly utilizing refrigeration condensation, solid / liquid desiccant adsorption, and membrane separation. Its core purpose is to control dew points, prevent material degradation, and optimize environmental or industrial process efficiency.
Dehydrating agent – It is a chemical substance which removes water molecules, including chemically bound hydrogen and oxygen atoms or water of crystallization, from other materials through a chemical reaction. Common examples include concentrated sulphuric acid (H2SO4), phosphorus pentoxide (P2O5), and hot aluminum oxide (Al2O3).
Dehydration – It is the unit operation or process of removing most of the water or moisture from a solid, liquid, or gas material. It relies on heat and mass transfer principles to lower moisture content to very low levels.
Dehydration reaction – It is a thermal process where chemically bound water, such as water of crystallization or hydroxyl groups, is removed from metal ores, hydroxides, or mineral compounds. This reaction typically converts hydrated minerals into anhydrous metal oxides and water vapour.
Dehydrogenation – It is a heat treatment process used to remove trapped hydrogen atoms from metals to prevent hydrogen embrittlement, internal stress, and micro-fractures.
Deicing chemicals – These are substances like chloride salts or glycols which melt ice by lowering water’s freezing point. These chemicals are important since their residual ions cause severe metal corrosion, pitting, and stress corrosion cracking in structural steels and highway infrastructure.
Deicing salt – It is a chloride-based chemical agent, primarily sodium chloride (NaCl), applied to frozen surfaces to lower the freezing point of water and melt ice. In metallurgy, it is studied for its aggressive role in inducing severe localized degradation, specifically pitting corrosion and stress corrosion cracking, in structural metals and alloys.
De-identification – It is the process of removing or modifying personally identifiable information (PII) and indirect identifiers within a dataset so that the remaining data cannot be traced back to a specific individual. It aims to balance data sharing utility with privacy protection.
Deionization – It is the removal of ions from a solution by any method. In the case of water, this typically refers to mineral ions such as sodium, iron, and calcium.
Deionized (DI) water – It is water which has had its charged mineral ions, such as sodium, calcium, iron, and chloride, removed, typically through ion exchange resins. This results in a high electrical resistivity and low conductivity, preventing scaling, corrosion, and chemical interference in engineering systems.
Delaminated area – It is a sub-surface zone where a material splits or separates into parallel layers, such as plies in a composite laminate, lifts in a concrete slab, or a coating from its substrate. This structural defect creates hidden internal voids that reduce load capacity.
Delamination – It is the separation of layers in a laminate or composite material because of failure of the matrix, either in the matrix itself or at the interface between the matrix and the fibre. It is either local or covering a wide area. It can occur in the cure or subsequent life.
Delamination area – It is the specific zone or surface measurement where bonded layers, plies, or coatings have split apart and separated from each other. It weakens structural strength in composite materials, concrete slabs, and coated metals.
Delamination damage – It is a failure mode where a layered material splits apart into separate individual layers. It happens when the bond holding the layers together breaks down under stress. This problem is very frequent in composite materials like carbon fibre, printed circuit boards, and reinforced concrete.
Delamination detection – It is the process of finding hidden separations or cracks between the layers of a layered material, such as a composite, concrete slab, or coated surface. Important methods include ultrasonic testing, acoustic emission, and thermal imaging.
Delamination factor – It is a ratio comparing the maximum damaged zone diameter to a nominal reference diameter, normal in drilled composite holes.
Delamination front – It is the advancing boundary line or crack tip where the separation of layers occurs inside a laminated composite material. It divides the bonded, intact region from the dis-bonded, separated layers under mechanical or thermal stress.
Delamination growth – It is the progressive, interlaminar separation of adjacent layers (plies) in a laminated composite material or bonded structure. It spreads along an internal crack front because of the static, cyclic fatigue, or environmental stresses, eventually leading to structural weakening or catastrophic failure.
Delamination length – It is the linear distance or extent of an internal crack-like separation between adjacent layers (plies) of a laminated composite material. It measures how far the bond has failed along the resin interface.
Delamination of composite – It refers to the separation of composite layers, which can occur because of the mechanical loads, impacts, or environmental variations, potentially reducing the stiffness and strength of the structure without visible signs.
Delamination onset – It is the exact point or moment when layers in a laminated composite material begin to separate from one another. It refers to the initiation of separation between layers in a material under cyclic loading, characterized by the number of cycles needed for this onset. It can be determined from a delamination onset curve derived from experimental data. It marks the start of structural failure between bonded plies or coatings.
Delamination propagation – It is the spreading or growth of a crack-like separation between the layers (plies) of a laminated composite material, coating, or adhesive joint. It occurs when applied mechanical loads, environmental stresses, or fatigue cycles overcome the interlaminar bonding strength, causing the damage area to enlarge and lead to structural failure.
Delamination size – It measures the physical dimensions, such as area, length, or radius, of a separation or gap between the bonded layers of a composite material or structural system. It determines structural integrity limits and dictates whether a defect needs minor injection repairs or major section replacements.
Delamination wear – It is a wear process in which thin layers of material are formed and removed from the wear surface. A ‘delamination theory of wear’ proposed by N.P. Suh in the early 1970s involves the nucleation and propagation of cracks so as to form lamellar wear particles. However, there are other ways to form lamellar wear particles (for example, by the loss of transfer layer fragments), and the term delamination wear is not to be used unless further clarification of the context of usage is provided.
Delaunay triangulation method – It is a computational geometry technique which connects a set of discrete points into a non-overlapping mesh of triangles. It ensures that the circumcircle of every triangle contains no other data points in its interior, maximizing the minimum angles of the triangles to prevent narrow, elongated shapes.
Delaware method – It is a technique used to calculate the shell-side heat-transfer coefficient and pressure drop in shell-and-tube heat exchangers. It uses ideal tube bank correlations and empirical correction factors to account for non-ideal leakage and bypass flows.
Delay-and-sum beamforming – It is a basic signal processing technique which applies specific time delays and weights to signals from a sensor array, then adds them together to amplify waves coming from a target direction. Also known as the conventional or Bartlett beamformer, it is widely used in acoustics, ultrasound imaging, and radar systems.
Delay angle – it is also called a firing or triggering angle. It is the phase angle of an alternating current (AC) wave at which a semi-conductor switch is turned on. It is used to control the timing of firing pulses in converter systems. It controls power conversion, motor speeds, and voltage output.
Delay circuit – It is an electronic arrangement designed to postpone the response or transit of a signal for a set time. These circuits control timing sequences, filter signals, and synchronize system operations. The circuit delay is dependent on the input key values.
Delay constraint – It is the minimum time interval needed between two consecutive events, or the maximum allowable duration for a signal to travel between an input and output. Delay constraints refer to the maximum duration allowed for the execution between the reception of an input event and the transmission of an output event within a function block network. These constraints are necessary for ensuring that real-time applications meet needed end-to-end delays. They ensure real-time systems and hardware circuits process data accurately without timing violations or race conditions.
Delay difference – It is the time difference between signals or modes traveling through different paths, such as differential pairs or optical fibre axes. It measures timing skew, which can distort data if it exceeds safe limits.
Delay distortion – It is a signal alteration occurring when different frequency components of a wave travel at unequal speeds through a medium, causing them to arrive at different times. It results from nonlinear phase response and media dispersion.
Delay diversity – It is a wireless communication transmission technique which sends time-delayed replicas of a signal across multiple antennas to convert spatial diversity into frequency diversity, improve signal reliability, and avoid fading.
Delayed ageing – It is also called delayed age hardening. It consists of retarding natural ageing by holding the alloy below room temperature. If the alloy is raised to room temperature, then natural ageing proceeds at the expected rate.
Delayed cracking – It is a structural defect where a material, typically high-strength steel or a welded joint, develops fractures hours, days, or even weeks after fabrication. It mainly occurs when three important conditions are met simultaneously. These conditions are diffusible hydrogen, susceptible micro-structure, and tensile residual stress. Delayed cracking is a kind of material failure frequently observed in advanced high strength steels (AHSS) with tensile strength above 800 mega-pascals (MPa.)
Delayed ettringite formation – It is a detrimental internal chemical reaction in hardened concrete which causes the material to expand and crack. It occurs when early curing temperatures exceed 70 deg C, which prevents the normal formation of ettringite. Later, when exposed to moisture, the delayed mineral forms within the rigid concrete matrix, generating internal stress.
Delayed fish-scaling – Fish-scaling is the appearance in a porcelain enamel coating in which the evolution of hydrogen from the base metal (iron or steel) causes loss of adhesion between the enamel and the base metal. Delayed fish-scaling occurs after the final porcelain enamel processing.
Delayed fracture – It refers to the phenomenon where a metal component, particularly high-strength steel, suddenly fails and cracks under a sustained, seemingly safe static load or residual stress after a period of time.
Delayed neutron – It is a free neutron released milliseconds to minutes after a nuclear fission event, originating from the radioactive beta decay of specific fission products rather than the split itself. Though the delayed neutrons make up less than 1 % of total fission neutrons, they stretch the reactor’s time response to a manageable scale.
Delayed neutron detection – It is a method used to monitor fuel damage in liquid metal-cooled reactors by measuring the neutron activity of coolant samples. It detects delayed neutrons generated by fission isotopes, indicating potential fuel failures and the presence of radioactive substances in the coolant.
Delayed neutron precursor – It is a radioactive fission product which undergoes beta decay to form an excited daughter nucleus, which then emits a delayed neutron. These delayed neutrons, although constituting less than 1 % of total neutrons from fission, are released on a slower timescale, facilitating the control of nuclear reactors. Key aspects include delayed neutron emission, beta decay timing, and reactor control.
Delayed quench – It is a heat-treating practice where a material is held in the air, or a controlled environment, for a specified time before being rapidly cooled. This interval allows the internal microstructure to alter slightly, intentionally slowing diffusion to relieve stress or manage grain precipitation.
Delayed-tack adhesive – It is a specialized polymer coating which remains dry and non-sticky at room temperature, allowing coated materials to be stacked or rolled without sticking. It becomes aggressively tacky and forms a strong bond only after being activated by an external stimulus, very frequently heat or thermal energy.
Delayed yield – It is a phenomenon involving a delay in time between the application of a stress and the occurrence of the corresponding yield-point strain.
Delay estimation – It is the process of calculating the time lag or propagation time difference of a signal, data packet, or physical response within a system. It is widely used in signal processing, VLSI (very large-scale integration) micro-electronics, and control systems to evaluate performance, ensure timing closure, or localize sources.
Delay ignition buffer – It is an important internal component found in non-electric detonators used in commercial blasting and mining operations. It typically sits above or within the pyro-technic delay element and performs a few important functions to ensure the blasting process operates safely and reliably. It serves as a grid or transfer element designed to safely transfer the low-energy shock wave from the shock tube evenly into the interior of the detonator.
Delay interferometer – It is an optical component which mixes an optical signal with a time-delayed fraction of itself, utilizing semi-transparent mirrors or wave-guide couplers to create two paths of different lengths for the light beams.
Delay profile – It is very frequently known as a power delay profile (PDP) in tele-communications. It is a measure which characterizes channel delay spread by showing the intensity or power of a received multipath signal as a function of time delay.
Delay screen – It is also known as a skim gate or skim strainer. It is a small, perforated sheet of metal. Placed at the top of the down-sprue, it deliberately restricts the flow of molten metal. This causes the pouring basin to fill completely, ensuring a smooth, continuous flow of clean metal.
Delay spread – It is a telecommunications metric which measures the time difference between the earliest arriving signal (like a direct line-of-sight path) and the last substantial reflected signal. It quantifies how much a transmitted pulse ‘spreads out’ or distorts as it takes multiple paths to reach a receiver. Understanding delay spread is important since it dictates how data is to be transmitted to avoid corruption.
Delay theorem – It is also known as the time-shifting property. It states that shifting a function in the time domain by a value ‘T’ multiplies its Laplace or Fourier transform by an exponential factor ‘e’ to the power ‘-sT’.
Delay-tolerant network – It is a computer network architecture designed to work in areas with unreliable, intermittent, or missing connection paths. Instead of assuming a constant end-to-end connection like the regular internet, it uses a store-carry-and-forward method to pass data step-by-step.
Delegation of power – It means transfer of certain responsibilities to the employees and giving them the required authority, which is necessary for the discharge of the responsibility properly. Delegation takes place when managers give employees the right to perform work on their behalf and in their name and the employees accept a corresponding duty or obligation to do which is required of them. Delegation is the dynamics of management, it is the process managers follow in dividing the work assigned to them so that they perform that part which only they, because of their unique organizational placement, can perform effectively, and so that they can get others to help them with what remains.
Deleted file – It is a file which the operating system has logically erased by removing its index pointer and marking its storage space as free. However, the actual data (the 1s and 0s) remains physically intact on the drive until it is overwritten by new data.
Deleterious substance – It is a substance which, if added to any water, degrades or alters or forms part of a process of degradation or alteration of the quality of that water so that it is rendered or is likely to be rendered deleterious to the aquatic life. It is also a water which contains a substance in such quantity or concentration, or that has been so treated, processed or changed, by heat or other means, from a natural state that it, if added to any other water, degrades or alters or forms part of a process of degradation or alteration of the quality of that water so that it is rendered or is likely to be rendered deleterious to the aquatic life.
Delithiation – It is the process of removing lithium ions (Li+) from a solid compound or battery electrode. It occurs during the charging phase of a lithium-ion battery when lithium leaves the cathode material and travels through the electrolyte to the anode. It is the direct opposite of lithiation (the insertion of lithium ions during battery discharge).
Deliverability – It refers to reservoir production potential, transmission system reliability, or project output execution. It measures a system’s capability to move resources or assets from a source to an end point under real-world constraints.
Deliverability test – It is a flow test used to measure a well’s production capacity and pressure behaviour against different back-pressures. It helps find key performance components like the flow coefficient (C) and exponent (n) to calculate the ‘absolute open flow potential’ (AOFP).
Deliverable – It is a final product or product component which is to be provided to a customer as per the contractual stipulations.
Delivered At Place (DAP) – ‘Delivered at Place’ means that the seller delivers when the goods are placed at the disposal of the buyer on the arriving means of transport ready for unloading at the named place of destination. The seller bears all risks involved in bringing the goods to the named place.
Delivered At Terminal (DAT) – ‘Delivered at Terminal’ means that the seller delivers when the goods, once unloaded from the arriving means of transport, are placed at the disposal of the buyer at a named terminal at the named port or place of destination. “Terminal” includes a place, whether covered or not, such as a quay, warehouse, container yard or road, rail or air cargo terminal. The seller bears all risks involved in bringing the goods to and unloading them at the terminal at the named port or place of destination.
Delivered Duty Paid (DDP) – ‘Delivered Duty Paid’ means that the seller delivers the goods when the goods are placed at the disposal of the buyer, cleared for import on the arriving means of transport ready for unloading at the named place of destination. The seller bears all the costs and risks involved in bringing the goods to the place of destination and has an obligation to clear the goods not only for export but also for import, to pay any duty for both export and import and to carry out all customs formalities.
Delivered Duty Unpaid (DDU) – It means that the seller delivers the goods to the buyer, not cleared for import and not unloaded from any arriving means of transport at the named place of destination. The seller has to bear all the costs and risks involved in bringing the goods thereto, other than, where applicable, any duty for import in the country of destination. Such duty has to be borne by the buyer as well as any costs and risks caused by his failure to clear the goods for import in time.
Delivered voltage – It is the actual electrical potential at a load or point of delivery, accounting for losses. Important factors include line drop, terminal pressure, and load impedance.
Delivery – It refers to the overarching processes and contractual frameworks used to take a product or system from the initial design phase to final completion and operation. Depending on the field, it mainly involves either project delivery methods (in construction / systems engineering) or engineering execution / deliverables (in product development).
Delivery method – It defines the contractual relationships, roles, and sequence of activities between the project owner, the designers, and the builders. It determines who is responsible for what, when they join the project, and how financial risks and scope are managed. The four most common delivery methods utilized in the industry include design-bid-build (DBB), design-build (DB), construction manager at risk (CMAR), and engineer, procure, construct (EPC).
Delivery performance – It is a quantitative measure of how reliably a team or system meets its schedule, quality, and output goals. It tracks speed, accuracy, and stability across technical projects or software releases.
Delivery pressure – It is also called discharge pressure. It is the output pressure exerted by a pump, compressor, or gas distribution system to push a fluid or gas through a system. It is needed to overcome total system resistance, including pipe friction, elevation changes, and component pressure drops.
Delivery protocol – It is a formal set of rules, procedures, and data formats governing the reliable transfer of data, software, or physical assets between systems or parties. Important components include sequence control, error handling, and acceptance criteria.
Delivery rate – It is the volumetric or mass flow rate of a fluid moved by a system per unit of time, or the project velocity in software development. It measures pump or system output and development pace.
Delivery roller – It is a final output or discharge cylindrical component in a system, such as a textile spinning frame, continuous steel casting line, or material handling conveyor, which it used to eject, feed, or transfer processed material forward.
Delivery vehicle – It is a specialized transportation mode optimized for the efficient, safe, and timely movement of goods, mainly in urban logistics, focusing on payload capacity, maneuverability, and power-train efficiency.
Delivery volume – It refers to the actual physical quantity or fluid quantity transferred through a system, or it describes financial trading volume terminology occasionally cross-referenced in quantitative systems analysis. It measures the net output or material moved past a designated point over a specific timeframe.
Delocalized electrons – These are valence electrons not confined to a single atom or covalent bond, but instead shared freely across multiple adjacent atoms or a lattice structure. This free movement is important for enabling electrical conduction, high thermal transfer, and structural stability.
DeLong diagram – It is a refinement of the Schaeffler diagram which is used in metallurgy, particularly for predicting the microstructure (specifically, the presence and quantity of ferrite) in stainless steels. It addresses the limitations of the Schaeffler diagram by incorporating the austenite-stabilizing effect of nitrogen, which is a strong austenite-forming element.
Delphi technique – It is an estimation method based on expert consensus. Experts make estimates individually and simultaneously and then review their estimates as a group before making another set of estimates. The process is repeated, with the pool of estimates typically becoming narrower after each round of review until a consensus is reached.
Delta ferrite – Delta ferrite is the high temperature form of iron, formed on cooling low carbon concentrations in iron-carbon alloys from the liquid state before transforming to austenite. In highly alloyed steels, delta ferrite can be retained to room temperature. It is a solid solution of one or more elements in body-centered cubic iron. Unless otherwise designated (for example, as chromium ferrite), the solute is normally assumed to be carbon.
Delta function – It is an idealized mathematical construct representing an infinitely tall, infinitely narrow spike whose total area equals 1. It is zero everywhere except at its designated centre, serving to model sudden impulses, point masses, or concentrated loads. It is a generalized function defined by two basic core rules namely it is zero everywhere except at zero, and its total integral over the entire real line equals one. Its most important characteristic is the sifting property, which extracts a function’s value at a specific point.
Delta function property – It refers to the requirement which as the smoothing length approaches zero, the smoothing function W(x – x’, h) converges to the Dirac delta function delta(x – x’). This property ensures that the smoothing function can accurately represent point values in the limit of no smoothing.
Delta iron – It is the solid phase of pure iron that is stable from 1,400 deg C to 1,539 deg C and possesses the body-centered cubic lattice.
Delta layer – It is the second layer of zinc iron alloy growth from the base steel formed during the galvanizing process. The chemical composition of the delta layer is around 90 % zinc and 10 % iron. The delta layer is 60 % harder than the base steel it protects from abrasion and corrosion. It is the thickest alloy layer in the galvanized coating. Reactive steels increase the delta layer thickness.
Delta modulation – It is a signal encoding technique which uses a one-bit (two-level) quantizer to create a staircase approximation of an oversampled baseband signal, adjusting the approximation by a fixed amount based on the difference between the input signal and the approximation. It is characterized by its simplicity and effectiveness in maintaining a close approximation to the input signal, provided that the signal does not change rapidly.
Delta modulator – It is an electronic circuit which changes an analog signal into a digital signal using just one bit per sample. It works by comparing the input signal to a stepped approximation of it, outputting a ‘1’ if the signal goes up or a ‘0’ if it goes down.
Delta operator – It is a mathematical operator used in the context of control systems, which approximates the dynamics of a system by representing changes in state variables through discrete-time differences, facilitating the design of controllers and observers in systems with disturbances.
Delta phase – It refers to a specific, stable structural form of an alloy or pure metal which exists at particular temperatures and compositions. Its exact definition depends on the metal system, very frequently to delta iron or the delta phase in superalloys. In pure iron and plain carbon steels, the delta phase (delta-ferrite) is an allotrope (a structural modification) of iron which exists at extremely high temperatures. In high-performance nickel-chromium alloys, the delta phase is an inter-metallic compound with the chemical formula Ni3Nb (nickel niobium).
Delta robot – It is a type of parallel-link robot used for ultra-fast, highly precise movements. It is typically mounted overhead. It uses three light-weight arms which converge at a central platform. Since the heavy drive motors are fixed at the base, the robot has minimal inertia and can execute over 100 picks per minute.
Delta rule – It is a supervised learning algorithm used to update the weights in artificial neural networks, specifically designed to minimize prediction error using gradient descent. It is also known as the Widrow-Hoff rule or the least mean squares (LMS) rule.
Delta value – It represents a change, difference, or tolerance in a measurement. It typically defines a calculated offset, a modification from a baseline dimension (e.g., in tabulated drawings), or the maximum permissible variation in physical properties like colour or geometry.
Delta-wye transformer – It is a type of connection of a three-phase transformer.
Demagnetization – It the process of reducing or removing the magnetic properties of an object. It is the opposite of magnetization. It scrambles the internal alignment of tiny magnetic parts so they stop pulling on metal. It is the process through which the remanent magnetization of magnetic grains is reduced or eliminated, particularly noted for multi-domain grains where it is influenced by the distribution of blocking temperatures that change with thermal conditions. This process is characterized by a broad spectrum of thermal demagnetization temperatures, especially as grain size increases.
Demagnetized state – It is a condition where a magnetic material has zero net magnetization since its internal magnetic domains point in random, opposing directions.
Demagnetizing factor – It is a geometry-dependent constant which relates the internal demagnetizing field to the magnetization of a magnetic sample. It defines how much the shape of an object reduces its internal magnetic field.
Demagnetizing field – It is an internal magnetic field created by a magnetized material which points in the opposite direction of its own magnetization. It tries to reduce the material’s total magnetic moment and depends heavily on the object’s physical shape. This field is uniform inside simple shapes like ellipsoids but changes across different parts of irregular objects.
Demand curve – It is a graph depicting the inverse demand function, a relationship between the price of a certain commodity (the y-axis) and the quantity of that commodity which is demanded at that price (the x-axis). Demand curves can be used either for the price-quantity relationship for an individual consumer (an individual demand curve), or for all consumers in a particular market (a market demand curve). It is normally assumed that demand curves slope down.
Demand equation – It is a mathematical formula showing how the quantity demanded of a good depends on its price and other economic factors. It typically follows a linear form like ‘Qd = a – bP’, where ‘Qd’ is the total quantity of a product which buyers want to purchase, ‘a; is the base quantity demanded when the price is zero (the intercept), ‘b’ is the slope coefficient showing how much demand changes when the price shifts, and ‘P’ is the price of the good or service.
Demand factor – It is the fraction of actual use of some quantity, related to the maximum which can be used in a specified time.
Demand flexibility – It is the ability of buildings, devices, and power systems to shift, reduce, or modulate their electricity use. Key concepts include load shifting, peak reduction, and grid balancing.
Demand forecasting – It is the process by which the future requirement for any product or service is estimated. It provides the suppliers the demand forecast data which helps them in matching the demand and supply and also in reducing the system-wide inventory. By using demand forecasting, an organization can predict the future demand for a specific product or service using past sales data and other information. Demand forecasting is a valuable organizational tool with which an organization can understand the potential sale the organization can make in the future. It is helpful for the management to make informed decisions about several organizational functions such as market potential, pricing and growth.
Demand forecasts – These are the predictive analytics used to estimate future customer demand for products, employing time-series approaches such as exponential smoothing and auto-regressive models to incorporate trends and seasonality. These forecasts are important for effective demand planning and sales and operations planning within supply chain management.
Demand management -It is a planning methodology which is used to forecast, plan for and manage the demand for products and services. This can be at macro-levels as in economics and at micro-levels within individual organizations. Demand management has a defined set of processes, capabilities and recommended behaviours for the organizations which produce goods and services.
Demand reduction – It means actions taken to lower the public desire or need for a specific good, or service. It focuses on changing human behaviour, education, and health support.
Demand response – It is a strategy where electricity grid operators provide incentives for consumers to temporarily reduce or shift their energy usage during periods of peak demand. It acts like a ‘virtual power plant’, stabilizing the grid, preventing black-outs, and helping integrate renewable energy.
Demand response programme – It is an energy management tool where utility organizations offer financial rewards or special pricing to customers who reduce or shift their electricity use during times of high grid stress or expensive market prices.
Demand-side ancillary services programme – It is a market-based energy programme which allows electricity consumers to offer load reductions, providing vital operating reserves and frequency regulation to stabilize the power grid.
Demand-side management – It is a utility-led strategy which encourages consumers to modify their energy usage patterns, either by reducing overall consumption or by shifting demand to off-peak hours. The main goal is to improve energy efficiency, improve grid reliability, and delay the need for costly power plant or infra-structure upgrades. Demand-side management (DSM) achieves these goals through two main approaches namely energy efficiency (EE), and demand response (DR).
Demand-side response – It is an energy management practice where consumers adjust their electricity consumption in response to grid conditions or price signals. Instead of ramping up generation to meet spikes in demand, demand-side response (DSR) temporarily shifts, reduces, or increases power usage to stabilize the electrical grid. Demand-side response typically operates through two main mechanisms namely price-based demand-side response, and incentive-based demand-side response.
Demand signal – It is a real-time or near-real-time data indicator, such as point-of-sale transactions, customer on-line orders, or inventory replenishment request, which shows actual product or service demand. It helps organizations replace slow, old forecasting methods with fast supply chain updates.
Demand wettability – It refers to a material’s ability to pull and absorb a liquid on-demand through capillary action. It defines the rate and volume of fluid a porous medium or surface is going to spontaneously soak up when subjected to a fluid source or negative pressure.
Demarest process – It is a fluid forming process in which cylindrical and conical sheet metal parts are formed by a modified rubber bulging punch. The punch, equipped with a hydraulic cell, is placed inside the work-piece, which in turn is placed inside the die. Hydraulic pressure expands the punch.
Dematerialization – It means reducing the total quantity of physical materials and energy needed to make a product or deliver a service. Key strategies include miniaturization, material substitution, and design optimization. It is te process of improving resource productivity by producing the same quantity of products and services using fewer materials.
Demineralized water – It is that water where are the minerals of the water has been removed. Demineralized (DM) water is also used as boiler feed water. The demineralization process is usually done when the water is to be used for chemical processes and the minerals present may interfere with the other chemicals. With the demineralization process, the water is softened by the removal of the undesired minerals. Demineralized water has a higher conductivity than deionized water.
Demister – It is a filter, made from metal or fibre-glass mesh, which is positioned at the gas outlet line to remove liquid droplets and provide a final ‘polish’ to the gas. Its liquid capacity is limited, and it is to be replaced during the overhaul of the separator.
Demodulation – It is the process of extracting an original information or message signal from a modulated carrier wave at a receiver. It reverses the modulation done at the transmitter to recover usable audio, video, or digital data.
Demodulation algorithm – It is a step-by-step mathematical or computational procedure used to extract the original information-bearing base-band signal from a modulated carrier wave. Executed within digital signal processors (DSPs), field-programmable gate arrays (FPGAs), or software-defined radios (SDRs), these algorithms isolate the underlying data, such as audio, video, or raw binary streams, by reversing the changes made to the carrier’s amplitude, frequency, or phase.
Demodulator – It is an electronic circuit or device which extracts the original information signal from a modulated carrier wave. It performs the exact reverse of the modulation process at the receiving end of a communication system.
Demography – It is the scientific study of characteristics and dynamics pertaining to the human population. The characteristics encompassed by this study include size, growth rate, density, vital statistics and distribution of a specified population.
Demolition – It is the planned, safe, efficient, and controlled destruction or dismantling of buildings or structures. It relies on engineering principles to ensure safety, structural stability, and efficiency.
Demonstrate compliance – It refers to the process by which manufacturers of the products provide technical documents which show that the products meet the basic principles of safety and performance as needed by the regulatory authorities.
Demonstration plant – It is an intermediate-scale industrial facility built to prove that a new technology works at a large scale, confirm financial and operational viability, and bridge the gap between small pilot tests and full-scale commercial production. It is an intermediate-scale facility constructed to validate the design and operational data from a pilot plant before scaling up to a commercial plant, utilizing data from both the pilot and modelling processes to address potential issues.
Demonstration test – it is a formal evaluation method used to prove that a system, component, or product meets specified operational, reliability, or performance requirements under representative conditions.
Demonstration unit – It is a working prototype or near-commercial scale model used to prove system concepts, train operators, and validate performance before full-scale commercial production.
Demo-programme – It is a trial software, a feature test, or a sample code. It lets users see how a tool works before they buy or use the full version.
Demultiplexer – It is a digital circuit which takes one single input and sends it to one of several outputs using select-lines. It acts like a data distributor. It is a digital information processor. It takes input from one source and also converts the data to transmit towards several sources.
Demultiplexing – It is the process of taking a single, combined signal or data stream and separating it back into its original individual signals. It is the exact reverse of multiplexing, which combines multiple data streams to save band-width during transmission.
Dendrimers – These are synthetic, nanos-scale macro-molecules with a highly ordered, branched, tree-like structure which originates from a central core. Unlike traditional linear polymers, their precise, starburst-like geometry allows them to encapsulate molecules within their interior or attach them to their highly functionalized outer surface.
Dendrite – It is a crystal which has a tree-like branching pattern, being most evident in cast metals slowly cooled through the solidification range.
Dendrite arm spacing – It is frequently referred to as secondary dendrite arm spacing (SDAS). It is the distance between the branches or arms of a dendrite, which is a tree-like structure formed during solidification of metals. Dendrite arm spacing (DAS) is a key parameter in describing the micro-structure of cast materials and is used to assess factors like tensile strength, fatigue properties, and the presence of defects.
Dendrite free – It is an electrode structure or battery design which prevents the formation of sharp, tree-like metal fibres (dendrites) during charging. This electrode structure prevents the formation of dendritic growth during electro-chemical processes, particularly in lithium-sulphur (Li-S) batteries, hence improving performance and longevity. It stops short circuits and extends battery life.
Dendrite shaped inclusions – These are dendrite shaped oxide and sulphide inclusions (separate and aggregated) formed because of excessive quantity of strong deoxidizer (aluminum). These inclusions have melting point higher than that of steel. Sharp edges and corners of the dendrite shaped inclusions can cause local concentration of internal stress, which considerably decrease the ductility, toughness and fatigue strength of the steel.
Dendritic nano-structures – These are intricate, tree-like formations at the nano-scale characterized by multiple branching arms extending from a central core. They provide a very large surface area and unique active sites.
Dendritic powder – It consists of particles normally of electrolytic origin typically having the appearance of a pine tree.
Dendritic segregation – It consists of inhomogeneous distribution of alloying elements through the arms of dendrites.
Dendritic white spots – These are a specific type of microstructural defect which appears when these branched crystal structures break off from the cooling wall or electrode and fall into the molten pool, where they resolidify as a distinct, localized cluster.
Dendritic zinc – It is a branched, tree-like crystal structure which forms when zinc deposits unevenly during electro-deposition. It grows during the charging of zinc batteries, driven by limited ion diffusion and rough electrode surfaces.
Denial-of-service (DoS) attack – It is a cyber-attack which makes a computer, website, or network resource unavailable to its real users. It works by flooding the target with fake traffic or overwhelming its system memory and processing power until it slows down or crashes.
Denickelification – It is the corrosion in which nickel is selectively leached from nickel-containing alloys. Most commonly, it is observed in copper-nickel alloys after extended service in fresh water.
Denier – It is a yarn and filament numbering system in which the yarn number is numerically equal to the weight in grams of 9,000 meters. It is used for continuous filaments. The lower the denier, the finer is the yarn.
Denitrification – It is the process of converting nitrogen compounds, such as nitrate, into gaseous forms like nitrogen oxides and nitrogen gas. It plays a significant role in the nitrogen cycle and is influenced by factors such as vegetation cover, land management, soil type, and weather conditions.
Denoised image – It is an approximation of the original image which results from the removal of noise from a noisy input image, improving its quality for accurate analysis and interpretation. This process utilizes different techniques, including non-local means filters and sparse representation methods, to maintain the integrity of relevant image information while reducing noise.
Denoising auto-encoders – These are a type of deep learning neural network which take corrupted data as input, compress it, and learn to reconstruct the original, clean data. Denoising autoencoder is a variation of auto-encoders designed to prevent overfitting by adding noise to the input data, which helps the model generalize better to new data by discouraging the memorization of small details.
Denoising auto-encoders provide a deliberately noisy or corrupted version of the input to the encoder, but still use the original, clean input for calculating loss. This trains the model to learn useful, robust features and reduces the chance of simply replicating the input.
Denoising problem – It is the challenge of recovering an original, clean signal or image from a corrupted, noisy observation. It relies on a signal model, a noise model, and a fidelity measure to separate true underlying patterns from random interference.
Denoising scheme – It is a structured method or algorithm used to remove unwanted noise from corrupted data, such as images, audio, or signals, while protecting important underlying features and details.
Denominator coefficient – It is a constant multiplier attached to a variable term located in the bottom part (denominator) of a mathematical fraction, rational function, or filter transfer model.
Denominator polynomial – It is a polynomial expression located on the bottom (denominator) of a rational fraction, frequently representing system poles in engineering.
DeNOx catalysts – These are materials, such as Ce (cerium) exchanged zeolites, which facilitate the selective catalytic reduction of nitrogen oxides (NOx) using reducing agents like ammonia or urea, demonstrating high activity and selectivity over a wide temperature range while minimizing the oxidation of sulphur di-oxide (SO2). DeNOx catalyst is a special material used in selective catalytic reduction (SCR) systems to clean factory or engine exhaust. It helps turn harmful nitrogen oxides into safe nitrogen gas and water using a helper fluid like ammonia or urea.
Dense conventional castables – These are created with high alumina cement and can withstand temperatures from 1,300 deg C to 1,800 deg C. These refractory castables are very good for common furnace applications, burner blocks, specialty muffle furnaces and boiler work. These castables are much stronger than insulating castables with strengths normally equaling those of normal firebrick of the same class. In dense conventional castables, hot strength behaviour with increasing temperature is principally dependent on the cement type (low, medium-purity, or high purity calcium aluminate cement), and the quantity used in the formulation.
Dense dislocation walls – These are narrow, planar boundaries of highly concentrated crystal defects (dislocations) which form in metals during plastic deformation (cold working). They separate microscopic areas of the metal which are relatively free of defects, creating an organized substructure which heavily influences the material’s strain hardening (work hardening) and strength.
Dense fluid – It is a state of matter where particles are tightly packed together, high mass is contained in a small volume, and molecules are close enough to constantly interact with neighbours.
Dense inorganic membrane – It is a non-porous solid material, such as a metal alloy or ceramic oxide, which separates specific gases like hydrogen or oxygen through crystal lattice diffusion rather than physical pore-size filtering.
Dense layer – It is a basic building block in deep learning where every neuron connects to every single neuron in the previous layer. It performs matrix math using weights and biases to help the computer find patterns in data. Dense layer is a fully connected layer in which all nodes from the previous layer are connected to all nodes in the subsequent layer, allowing for multiple levels of representation in the data.
Dense membranes – These are non-porous structures composed of a thick layer which allows penetrants to diffuse under the influence of electrical potential, concentration, or pressure gradients, with separation based on the relative transfer rates of components governed by their diffusion and solubility in the membrane material. Dense membrane separates substances using a solution-diffusion mechanism driven by pressure, concentration, or electrical gradients.
Dense metal – It is a material which has a high mass packed into a small volume, meaning it feels very heavy and solid for its size.
Dense metallic membrane – It is a nonporous, metal-based barrier, mainly made of palladium or its alloys, which separates ultra-pure hydrogen from gas mixtures using a solution-diffusion process.
Dense palladium (Pd) membrane – It is a non-porous metal barrier which separates ultra-pure hydrogen from gas mixtures using a solution-diffusion process, achieving infinite selectivity for hydrogen over other gases.
Dense phase conveying capability – It is the ability to transport dry bulk materials at low velocity and high pressure using a high solids-to-air ratio. It involves moving materials in dense plugs or slugs rather than as suspended particles.
Dense phase flow – It is a pneumatic conveying method which moves dry bulk materials through pipelines using high pressure and low air velocity, typically propelling solids in plugs or slugs rather than keeping them suspended in the air.
Dense refractories – These are shaped refractory products with specific dimensions, having a true porosity less than 45 % by volume. These refractories have high-density and offer very good resistance in challenging operating environments, such as slags with different chemical compositions, fumes, dust, and gases.
Dense sand – It is a tightly packed granular soil characterized by a high relative density higher than 65 %, high load-bearing capacity, and a tendency to dilate under shear stress.
Dense small cell – It refers to a network architecture in 5G cellular systems characterized by a high concentration of small cell base stations which facilitate increased capacity and improved coverage while posing challenges in power consumption and back-haul traffic management.
Dense wave-length division multiplexing – It an optical technology which increases data capacity by transmitting multiple signals concurrently over a single optical fibre. It uses tight wave-length spacing, operates near the 1,550 nano-meter band, and supports 80 plus channels.
Densification – It refers to the compacting process of material under specific conditions, such as palletization, briquetting, and extrusion. It is widely used in different industries to increase bulk density, improve transportation, reduce dust generation, and enhance handling and logistics efficiency.
Densification characteristic – It is a specific measure of how a material decreases in volume and increases in density under pressure, heat, or chemical treatment. It includes key factors like porosity reduction, compressive strength, and durability gain.
Densification process – It is a hot powder forging process in which an unsintered, pre-sintered, or sintered preform made out of powders is forged to higher densities. It has the advantage of powder metallurgy such as dimensional accuracy and minimum materials waste, along with the high strength of forging. Plastic deformation and volume change of the sintered powder materials is different from those of the conventional cast materials because of the porosity in the former case.
Densitometer – It is a precision instrument which measures the optical density (degree of darkness or opacity) of a material or the specific gravity of a substance. In metal and industrial foundries, a densitometer is used in non-destructive testing (NDT) to check the quality of X-ray radiographic films used to inspect castings for internal defects.
Density – It defines how much mass a metal contains per unit of volume. It dictates a metal’s heaviness and compactness, impacting applications like aerospace (lightweight metals) and shielding (heavy metals).
Density, absolute – It is the mass per unit volume of a solid material, expressed in grams per cubic centimeter or kilograms per cubic metre.
Density, apparent – It is the weight in air of a unit volume of a material.
Density, bulk – It describes the measure of mass and volume including the pore space. Bulk density is normally considered in conjunction with apparent porosity. It is a measure of the weight of a given volume of the material.
Density change – Density change of a substance needs altering its temperature, pressure, or mass-to-volume ratio.
Density, core – Core density is the mass per unit volume of a central structural material, planetary centre, or stellar interior. It defines how tightly packed the matter is inside that middle region compared to outer layers.
Density distribution – It describes how a physical property, mass, or statistical probability is spread out across a space, area, or range of values. It shows how matter or energy fills a volume. In statistics, it is shown as a curve where the total area equals one.
Density, drilling fluid – It is normally called mud weight. It is the mass or weight of drilling mud per unit volume. It is typically measured in grams per cubic centimeter. This property creates the necessary hydrostatic pressure in the wellbore.
Density, drive – It normally refers to disk density or recording / areal density in data storage hardware, describing how closely data bits are packed onto a storage medium.
Density drive sampler – It is a geotechnical tool used to determine the in-place density of soil by driving a thin-walled core tube into the ground to collect a relatively undisturbed sample.
Density estimate – It is the calculation of an unobservable population probability curve using a sample of observed data. Key methods include histograms, parametric fitting, and kernel smoothing.
Density estimation – It is a statistical method used to build a guess of an unknown probability density function based on observed data samples. Key methods include histograms, parametric estimates, and Kernel density estimation.
Density expansion – It is the decrease in a substance’s density caused by an increase in its volume when heated. It also refers to the mathematical expansion of the total correlation function in powers of density for a homogeneous, isotropic system, where the zeroth-order term relates to the radial distribution function at low density. It shows how density-dependent terms in the correlation function behave at varying separations, particularly highlighting their convergence or divergence based on the nature of the pair potential.
Density, fabric – Fabric density is a measure of how tightly yarns are packed into a textile, expressed as threads per centimeter or mass per unit area / volume (such as grams per square meter). It determines material weight, structural strength, and feel.
Density fluctuation – It is the random or localized change in particle number, mass, or energy density of a system relative to its average back-ground value. These variations occur across space and time because of the thermal energy, quantum mechanics, or kinetic activities.
Density fraction – It is a specific portion of a mixture separated out during a density-based sorting process, or it describes the fraction of a space filled by matter (packing fraction). It typically splits materials by their mass-to-volume properties.
Density functional theory – It is a widely used quantum mechanical modeling method in physics, chemistry, and materials science used to calculate the electronic structure of atoms, molecules, and solids. It allows scientists to predict material properties, such as energy, reactivity, and conductivity, without needing prior experimental data.
Density gradient – It is a change in the density of a substance over a specific distance, normally created by layering liquids of decreasing concentration from the bottom to the top of a tube.
Density log – It is a continuous well-logging tool record which measures the bulk density of rock formations along a bore-hole. It determines electron density by emitting gamma rays and counting how many bounce back after hitting electrons in the rock. It is a measurement tool which assesses the formation density around a bore-hole and derives overall porosity by detecting low-energy gamma rays after their interaction with the formation’s electrons. It utilizes a gamma ray source and multiple detectors to estimate electron density, which is necessary for calculating porosity based on known densities of the rock matrix and contained fluid.
Density matrix – It is a mathematical tool in quantum mechanics used to describe the statistical state of a physical system. It handles both pure states (complete knowledge) and mixed states (statistical mixtures with incomplete knowledge).
Density methods – These are the techniques which model the probability density function of observations for a sample belonging to a specific class, utilizing the super-position of individual contributions from training objects, represented as potential fields. These methods do not assume a priori shape for the density function but derive it from the training data.
Density of gases – It is the mass of a unit volume of gas at a stated temperature and pressure.
Density of materials – It depends on microstructure evolution under pressure, gas pressure sintering, hot pressing, or hot isostatic pressing. It also depends on type of additive incorporated during sintering. There are roles of starting materials in getting high density.
Density of solids and liquids – It is the mass of a unit volume of a material at a specified temperature.
Density operator – It is a mathematical tool used in quantum engineering and physics to describe the statistical state of a quantum system, defined as a positive semidefinite operator with a trace equal to 1. It handles both pure and mixed states when a system is not fully known.
Density particle – It is defined as the ratio of the actual mass of a particle to its actual volume, accounting for the presence of internal pores within the particle.
Density perturbation – It refers to fluctuations in the energy density of a system, which can manifest as either entropy or adiabatic types. These perturbations can be characterized by variations in the relative number densities of different particle types or inhomogeneities in spatial curvature.
Density, photographic – Photographic density also called optical density, measures the degree of darkening on an exposed and processed X-ray film. It is defined as the base-10 logarithm of the film’s opacity, which calculates exactly how much light is blocked when viewing the image.
Density polyethylene – It refers to a category of polyethylene classified based on its density, with low-density polyethylene (LDPE) characterized by a density of 0.910 grams per cubic centimeters to 0.925 grams per cubic centimeters and high-density polyethylene (HDPE) defined by a density greater than 0.940 grams per cubic centimeters. Low-density polyethylene has a branched structure leading to lower density and crystallinity, while high-density polyethylene features a linear form resulting in higher density and crystallinity.
Density ratio – It is the comparison of the density of one substance to a reference substance, also known as relative density or specific gravity. It has no units. It is the ratio of the determined density of a powder compact to the absolute density of metal of the same composition, normally expressed as a percentage. It is also referred to as percent theoretical density.
Density, relative – It is also called specific gravity. It is a dimensionless quantity and defined as the ratio of the density (mass of a unit volume) of a substance to the density of a given reference material. Relative density for solids and liquids is nearly always measured with respect to water at its densest (at 4 deg C) and for gases, the reference is air at room temperature (20 deg C). The term ‘relative density’ is preferred, whereas the term ‘specific gravity’ is gradually being abandoned.
Density separation – It is a method used to sort and divide mixed materials based on differences in their mass per unit volume. It relies on a fluid medium, such as air, water, or heavy liquids, where items with lower density float or rise, and heavier items sink.
Density stratification – It is the vertical layering of fluids or gases caused by differences in density, where heavier layers stay at the bottom and lighter layers float on top. It is caused by variations in density, which can influence turbulent mixing and buoyancy forces within a body of water. This stratification can suppress overturning turbulent eddies and affect the mixing phenomena in the bottom boundary layer (BBL) under specific conditions.
Densmix powders – These powders refer to specialized, pre-mixed metal powder blends which include specific binders and lubricants. They are engineered to improve flowability and compressibility, enabling manufacturers to achieve higher material density in complex, pressed metal parts.
Dent – For rolled products, it is a sharply defined surface impression on the metal which can be caused by a blow from another object. For extrusions, it is a synonym for handling mark.
Dented pipe – It is a tube with a permanent, inward physical deformation which flattens or alters its circular cross-section, reducing its internal diameter. It is a pipe which has suffered local damage characterized by an indentation, which affects its collapse resistance. The degree of denting is evaluated based on the ovalization of the deformed cross section, correlating to the collapse pressure of the pipe.
Dent, expansion – It is a localized surface deviation from flat generated by expansion of vapour during thermal treatment of cold-rolled coiled sheet.
Dent, repeating – It consists of repeating depression caused by a particle adhering to a rotating roll over which the metal has passed.
Dent depth – It is the maximum inward drop or reduction in a material’s original outer diameter or surface level. It measures the peak localized indentation distance and serves as a main safety metric in pipeline engineering to evaluate structural risk.
Dent resistance – It is the ability of materials, such as wood-plastic composites (WPC), to withstand indentation and deformation when subjected to impact from moving or stationary objects. Dent resistance is measured by the minimum force or energy needed to form a lasting dent. It is typically measured using techniques like the Janka test and falling ball impact resistance tests.
Denudation – It is the geological process in which moving water, ice, wind, and waves erode the earth’s surface, leading to a reduction in elevation and in relief of landforms and landscapes. Although the terms erosion and denudation are used interchangeably, erosion is the transport of soil and rocks from one location to another, and denudation is the sum of processes, including erosion, which result in the lowering of earth’s surface.
Denuded zone – It is a region near a surface or grain boundary where crystal defects, voids, or impurity precipitates are absent or greatly reduced. It is also an area of land where the natural plant cover, trees, or topsoil have been stripped away.
Deoxidation – It is the removal of excess oxygen from the molten metal. It is normally carried out by adding materials with a high affinity for oxygen.
Deoxidation equilibrium – It is the chemical balance between dissolved oxygen and deoxidizing elements in a molten metal melt, defined by an equilibrium constant that dictates the lowest possible oxygen limit for a given quantity of deoxidizer.
Deoxidation products – These are those non-metallic inclusions which form as a result of adding deoxidizing agents to molten metal.
Deoxidation reaction – It is a chemical process which removes oxygen from a compound or reduces oxygen content, functioning directly as a reduction and electron-gaining reaction within a broader redox system.
Deoxidized copper – It is the copper from which cuprous oxide has been removed by adding a deoxidizer, such as phosphorus, to the molten bath.
Deoxidized steel – It is the steel which has been treated with a strong deoxidizing agent, such as silicon or aluminum, to considerably reduce its oxygen content, preventing reactions between carbon and oxygen during solidification. This process results in a more uniform steel which is normally harder than rimmed steel.
Deoxidizer – It is a substance which can be added to molten metal for removing either free or combined oxygen.
Deoxidizing – It is the removal of oxygen from molten metals through the use of a suitable deoxidizer. Sometimes it refers to the removal of undesirable elements other than oxygen through the introduction of elements or compounds which readily react with them. In case of metal finishing, it is the removal of oxide films from metal surfaces by chemical or electro-chemical reaction.
Deoxygenated water – It is the water which has had its dissolved oxygen gas removed, lowering the concentration of oxygen while leaving the core H2O molecular structure unchanged.
Deoxygenation – It is the biological, chemical, or environmental process of removing oxygen from a substance, such as water, or a chemical compound.
Deoxygenation step – It is the chemical or physical process of removing oxygen atoms from a molecule or extracting dissolved molecular oxygen from a liquid, gas, or environment.
Departure angle – It is the maximum slope angle a vehicle can descend or exit without the rear bumper or undercarriage dragging on the ground. It is measured between the ground and a line drawn from the rear tyre’s point of contact to the lowest rear hanging part of the vehicle.
Departure point – It refers to (i) the origin location in transportation and traffic engineering, (ii) the origin points of a trajectory in fluid dynamics and semi-Lagrangian schemes, and (iii) a formal deviation from technical design standards.
Depassivation – It is the loss or removal of a metal’s protective passive surface film, leading to active corrosion. Key triggers include aggressive chemical agents, shifts in pH balance, and electrical or mechanical stress.
Dependence – It is one of the explanatory analysis techniques. It is concerned with the impact of a set of predictor variables on a single outcome variable. For dependence techniques the common tools used are (i) analysis of variance (ANOVA), (ii) multiple analysis of variance (MANOVA), (iii) structural equation modelling, (iv) logistic regression, and (v) multiple discriminant analysis.
Department – It is a specialized, distinct division or section of a larger organization responsible for a specific function or area of work. Departments group resources and personnel by their function, product, or skill set to maximize efficiency.
Dependency – It is a logical relationship between project activities in a network diagram which determines when a dependent activity can begin.
Dependability – It is the ability of a system to deliver service which can be justifiably trusted, combining core attributes like reliability, availability, and maintainability. It acts as an overarching quality frame-work ensuring a system works as needed under specified conditions over time.
Dependence, frequency – Frequency dependence means a system, property, or process changes its behaviour or value as the frequency of an input signal, wave, or relative population trait changes.
Dependence method – It refers to a modelling approach which establishes relationships among random variables, frequently utilizing techniques such as joint normal transform and graphical models to address challenges related to correlation matrices and uncertainty in high-dimensional systems.
Dependent attenuation – It describes a reduction in signal strength or wave amplitude which varies as per the specific physical parameters, very frequently frequency, distance, or material properties. Unlike fixed loss, dependent attenuation changes dynamically as operating conditions shift.
Dependent behaviour – It means a material, system, or component changes its response based on external conditions like stress, time, or load. It shows how a property reacts when another factor shifts. It refers to the characteristics of materials which change over time in response to applied stress or shear rate, exemplified by thixotropic and rheopectic behaviours, where the material’s viscosity and shear stress either decrease or increase, respectively, under constant shear conditions.
Dependent cells – These are the cells which need attachment to a substrate for survival, as their lack of contact with a matrix can lead to apoptosis. This anchorage-dependent behaviour influences different cellular functions such as adhesion, migration, proliferation, and differentiation.
Dependent dielectric constant – It is very frequently frequency-dependent or temperature-dependent relative permittivity. It describes how an insulating material’s ability to store electrical energy changes when external physical conditions shift. As environmental frequency or heat alters, internal molecular polarization mechanisms lag or activate, changing the net effective value.
Dependent dielectric function – It is a frequency-dependent or wave-vector-dependent dielectric function. It is a complex mathematical expression defining how a material’s polarization and energy storage respond to changing electromagnetic fields or spatial variations. It links internal charge shifts to external stimuli across different frequencies.
Dependent failures – These are failures of two or more elements of a system where these failures cannot be considered independent (q.v.). Common cause and common mode failures are dependent failures.
Dependent friction – It refers to a frictional resistance which varies directly with external mechanical factors, mainly the normal load pressing two surfaces together and the specific properties of the interacting materials. It contrasts with independent variables like apparent contact area.
Dependent hysteresis – It is very frequently called rate-dependent hysteresis. It is a dynamic phenomenon where a system’s output lags behind its input. This lag and the resulting response loop change size and shape depending on how fast or slow the input value changes.
Dependent interaction – It refers to a relationship or process where the effect, strength, or outcome of an action between two or more variables, species, or components relies directly on specific conditions, time, or the presence of another factor.
Dependent Lyapunov function – It is a scalar energy-like function whose structure varies dynamically with system parameters, operating modes, or states. It extends traditional fixed Lyapunov stability analysis to complex setups like switched, non-linear, or parameter-varying systems.
Dependent material – It specifies material properties which change in response to external environmental factors, such as temperature, frequency, or stress rate, rather than remaining constant. These dynamic properties are important for accurate computer simulations.
Dependent mechanical properties – These are material characteristics which change based on external environmental conditions, internal structural orientation, or composite design, such as how temperature, fibre alignment, or loading rate alter a material’s strength and stiffness.
Dependent process – It is an action, task, or system operation which relies on the completion, resources, or output of another prior process (the predecessor) to begin or function properly. If the parent process fails or delays, the dependent process is directly affected or blocked from running.
Dependent stiffness – It refers to a mechanical property where an object or material’s resistance to deformation is not constant, but actively changes in response to an external factor, variable state, or environment. Instead of having a fixed ratio of force to displacement, its stiffness value depends directly on specific physical conditions.
Dependent strain – It a material deformation response which acts as a mathematical or physical function of independent variables like applied stress, loading history, or time. It contrasts with an independent strain set directly through fixed boundary displacements.
Dependent t-test – It is a data analysis procedure which assesses whether the means of two related groups are statistically different from each other, for example, one group’s mean score (time one) compared with the same group’s mean score (time two). It is also called the paired samples t-test.
Dependent variable – A variable is considered dependent if it depends on an independent variable. Dependent variables are studied under the supposition or demand that they depend, by some law or rule, on the values of other variables.
Dependent voltage source – It is a power source whose output voltage changes based on a specific voltage or current in another part of the circuit. It is split into two main types: voltage-controlled voltage sources and current-controlled voltage sources.
Dephosphorization – It is the chemical process of removing or reducing phosphorus from a substance, very frequently applied in metallurgy during steelmaking to prevent metal brittleness.
Depleted layer – It is a region near a solid–liquid interface where the density of a liquid, such as water, is reduced compared to the bulk density, potentially occurring on a sub-molecular level. The depletion distance quantifies this effect by measuring the density difference across this layer.
Depleted oil – It refers to the petroleum reservoirs or fields where the recoverable oil has been largely extracted, resulting in a permanent drop in internal fluid pressure and a sharp decline in production rates.
Depleted uranium – Depleted uranium is uranium mainly composed of the isotope uranium-238. Typically, it has a percentage of uranium-235 smaller than the 0.7 % found in natural uranium. It is obtained from used fuel elements or as by-product tails, or residues, from uranium isotope separation.
Depletion – It is selective removal of one component of an alloy, normally from the surface or preferentially from grain-boundary regions.
Depletion force – It is an effective attractive force which occurs between large macro-particles or colloids suspended in a fluid containing smaller solutes or polymers (depletants). When large particles move close together, smaller molecules are squeezed out from the gap, creating an osmotic pressure imbalance which pushes the large particles together.
Depletion layer – It is a narrow transition zone at a p-n junction in semi-conductor devices which is completely free of mobile charge carriers (free electrons and holes). It contains only fixed, ionized donor and acceptor impurity atoms, creating an internal electric field that acts as a barrier to current flow.
Depletion number – It is a dimensionless value which measures the rate of resource exhaustion or exergy loss relative to resource recycling and input within a thermodynamic or industrial system. It provides a measure of system progress or maturity. It is a useful basis for studying the evolution of resource depletion patterns and the implementation of resource conservation strategies.
Depletion region – It is an insulating transition zone within a semi-conductor p-n junction where mobile charge carriers are absent, leaving behind fixed, ionized donor and acceptor impurities which create a built-in potential barrier opposing current flow.
Depletion region width – It is the physical distance across a semi-conductor junction where mobile charge carriers are absent, leaving behind fixed, ionized impurity atoms. This zone sets the electronic barrier controlling current flow in devices like diodes and transistors.
Depletion zone – It is an insulating area within a conductive, doped semi-conductor where mobile charge carriers have diffused away, leaving behind fixed, ionized donor or acceptor impurities that block current flow. It is also the region around macro-molecules from which non-adsorbing polymers are excluded, resulting in an increase in the accessible volume for the polymers and leading to attractive interactions between the macro-molecules.
Deployable structure – It is a system which can change its shape and size. It packs into a small, tight space for easy transport or storage. Then, it unfolds or expands into a much larger size to do its job. It can lock into place to hold heavy loads.
Deployment – It means the strategic positioning, arrangement, or bringing into effective use of resources, personnel, or systems.
Deployment platform – It is a self-service system or internal framework which automates how software moves from code into production. It abstracts complex infrastructure, giving developers standard tools to build, test, and release applications safely without managing raw servers.
Deployment scenario – It specifies where, how, and under what constraints hardware and software components are installed, configured, and operated in a target environment. It maps out system topologies, operational work-flows, and infrastructure requirements to ensure reliable transition from development to live production.
Deployment process – It normally spans several core activities and specific sub-stages to ensure the software transitions smoothly from a developer’s machine to real-world usage.
Deployment valve – It is also called a downhole deployment valve (DDV). It is a surface-controlled, full-bore isolation valve integrated into a well’s casing string to isolate high-pressure subterranean formations from the upper well-bore. It safely holds reservoir pressure below while allowing the section above to vent during tool deployment or tripping operations.
Depolarization – It is a decrease in the polarization of an electrode.
Depolarization wave – It is a moving electrical impulse which travels across a cell membrane. It changes the internal charge of the cell from negative to positive by letting positive ions rush inside.
Depolarizer – It is a substance which produces depolarization.
Depolymerization – It is the chemical process of breaking large polymer chains (like plastics or resins) back down into their smaller basic building blocks, known as monomers or small oligomers. It is the reverse of polymerization and serves as a core method for advanced chemical recycling.
Deposit – It is the coating or layer of surfacing material applied by a thermal spraying process. In geology, it is an anomalous occurrence of a specific mineral or minerals within the Earth’s crust.
Deposit attack or corrosion – It is the corrosion which is occurring under or around a discontinuous deposit on a metallic surface. It is also called poultice corrosion.
Deposited atom – It is an individual particle transferred from a vapour, liquid, or plasma phase to bind onto a solid foundation, called a substrate. This atom-by-atom or layer-by-layer building process creates ultra-thin, uniform functional films used in micro-electronics, coatings, and nano-technology.
Deposited electrode – It is a conductive metal layer applied directly onto a substrate, such as a gas-sensitive membrane, semi-conductor, or sensor, through electrode-position or chemical coating to facilitate electrical contact and current flow.
Deposited energy – It normally refers to directed energy deposition (DED), a 3D printing process which melts wire or powder with a laser, electron beam, or plasma arc as it is placed on a surface. It can also mean the total heat or energy transferred to a material during thin-film coating or manufacturing.
Deposited film – It is an ultra-thin layer of material, ranging from single atoms up to several micro-meters thick, applied to a substrate surface. It alters the electrical, optical, mechanical, or chemical properties of a component.
Deposited mass – It is the total quantity of material added to a surface or substrate during a coating, plating, or thin-film growth process. It is typically measured in units of mass per unit area, such as micro-grams per square centimeter or grams per square meter.
Deposited material – It is any substance, metal, ceramic, or polymer, added layer by layer onto a base surface (substrate) through chemical, physical, or electrical processes to form a coating, thin film, or functional 3D structure.
Deposited metal – It is the filler metal which has been added during welding.
Deposited nano-fibre – It is an ultra-fine thread with a diameter under 1,000 nano-metres which is formed and laid onto a target collector surface through directional synthesis methods like electro-spinning or vapour deposition. These structured layers yield high porosity and massive surface areas.
Deposited structure – It refers to a solid layer, thin film, or micro-geometry built up on a substrate atom-by-atom, molecule-by-molecule, or layer-by-layer through chemical, physical, or electro-chemical processes. These structures form the back-bone of semi-conductor devices, protective surface coatings, and additive manufacturing parts.
Deposition – It is the process of applying a material to a base by means of vacuum, electrical, chemical, screening, or vapour methods. It is frequently with the assistance of a temperature and pressure container.
Deposition amount – It refers to the total accumulated quantity, mass, or thickness of a substance transferred onto a surface or structure from a gas, liquid, or particle-laden flow over a given time.
Deposition area – It is a specific location where materials, such as sediments, soil, or particles, accumulate since the carrying force of water, wind, or gas flow drops. This reduction in velocity or energy causes suspended matter to settle out and build up.
Deposition behaviour – It describes how atoms, ions, particles, or liquid droplets transfer from a gas, liquid, or plasma phase and accumulate onto a surface to form a solid film, coating, or sediment layer. It is governed by mass transfer, fluid dynamics, surface energy, and kinetic impact.
Deposition conditions – These refer to the precise environmental and operational parameters, such as temperature, pressure, gas flow rates, and voltage, controlled during a manufacturing process to build thin solid films, coatings, or layers onto a substrate.
Deposition efficiency – In arc welding, it is the ratio of the weight of deposited metal to the net weight of filler metal consumed, exclusive of stubs. In thermal spraying, the ratio, usually expressed in percent, of the weight of spray deposit to the weight of the material sprayed.
Deposition flux – It is the rate at which mass, particles, or chemical species are transferred and accumulate onto a specific surface per unit area per unit time. It is typically expressed in units like kilograms per square meter second or number of particles per square meter second.
Deposition fraction – It is the ratio of the mass or number of suspended particles which stick to a surface to the total mass or number of particles entering that system or region.
Deposition head – It is the critical tool-end assembly in additive manufacturing, 3D printing, or surface coating systems. It houses the delivery mechanisms, such as laser optics, powder / wire nozzles, gas shielding lines, or fluid injectors, which accurately melt, spray, or extrude material onto a substrate.
Deposition height – It is the vertical distance or thickness of material added onto a substrate during manufacturing processes like 3D printing, welding, or surface coating. It measures how high each new layer or built-up feature rises.
Deposition line – It typically refers to an automated manufacturing or thin-film processing line where sequential physical or chemical steps apply functional layers, coatings, or materials onto a substrate (such as glass, silicon wafers, or metal parts).
Deposition mechanism – It refers to the fundamental physical or chemical process by which atoms, molecules, or particles transfer from a source (gas, liquid, or plasma) and accumulate onto a solid substrate to form a thin film, coating, or layer.
Deposition method – It is a process used to apply a controlled layer of material, from single atoms to millimeters thick, onto a solid surface (substrate) to alter its electrical, mechanical, optical, or chemical properties.
Deposition parameters – These are the specific, controlled operational variables, such as temperature, pressure, voltage, and gas flow rate, set during thin-film or material coating processes like chemical vapour deposition (CVD) or physical vapour deposition (PVD). These settings directly determine the final layer’s thickness, structure, and quality.
Deposition process – It is a controlled technique used to add a layer of material atom-by-atom, molecule-by-molecule, or through fine particles onto a solid base (substrate). It is used to manufacture thin films, micro-structures, or thick protective and functional coatings.
Deposition rate – In thermal spraying, it is the weight of material deposited in a unit of time. It is normally expressed as kilograms per hour.
Deposition sequence – It is the order in which the increments of weld metal are deposited.
Deposition system – It is the equipment used to apply ultra-thin layers of atoms, molecules, or ions onto a target surface (substrate) to build functional, protective, or structural thin films. These systems control physical or chemical phase changes to alter a material’s optical, electrical, or mechanical properties.
Deposition technology – It is the process of applying microscopic or ultra-thin layers of atoms, molecules, or ions onto a solid surface (substrate) to build functional, protective, or decorative thin films. It alters surface properties like electrical conductivity, wear resistance, and optics.
Deposition temperature – It is the controlled heat level of a substrate or reaction chamber where thin films, coatings, or crystals grow from vapour or chemical precursors. It dictates film quality, crystal structure, and surface stickiness.
Deposition time – It is the total duration which a material is actively applied, grown, or coated onto a solid surface or substrate during a manufacturing or chemical process.
Deposition treatment – It is a surface modification or manufacturing process which adds a solid layer of material, atom by atom, molecule by molecule, or through larger particles, onto a base substrate to alter its electrical, mechanical, chemical, or optical properties.
De-powdering – It is the post-processing step in additive manufacturing (3D printing) where loose, un-fused powder is removed from the surfaces, internal channels, and complex cavities of a printed component. It transitions a raw, powder-encased build into a clean part ready for sintering or final use.
Depreciation – It is the periodic, systematic charging to expense of plant assets reflecting the decline in economic potential of the assets.
Depreciation method – It refers to the systematic approach used to allocate the reduction in value of an asset over its useful life, which can be calculated using different techniques such as the straight-line method or the sum-of-years digits method.
Depression angle – The angle of depression is the downward acute angle measured from a horizontal reference plane to the line of sight when looking at an object or target located at a lower elevation.
Depressions – In continuous casting process, these are local deformations in the cast surface. Depressions can be longitudinal or transverse. Longitudinal depressions appear like the shallow ditches oriented along the length of the cast product. They occur due to the uneven heat transfer in the mould. These depressions can be controlled by uniform cooling in the mould, by centering of the liquid steel jet in the mould, by controlling the fluctuations of the mould steel level, use of a casting powder with suitable viscosity and melting characteristics, and by regularly monitoring the degree and uniformity of the mould wear. Transverse depressions can occur cyclically along the strand length. The peritectic steels with low carbon and high manganese contents and the stainless steels are sensitive to this defect. The transverse depressions can be caused by the fluctuations in the mould level, large quantity of casting powder, and by the turbulence of steel the sub-meniscus level. These depressions are controlled by controlling the mould steel level, having proper mould taper, use of a casting powder with suitable viscosity and melting characteristics, and proper positioning of the input nozzle and its support.
Depressuring system – It is also called blowdown system. It is a safety mechanism designed to rapidly and safely reduce the internal pressure and inventory of process equipment during an emergency, such as an external fire, containment leak, or runaway reaction.
Depressurization – It is the process of releasing or losing the pressure inside a closed space or container. It is the controlled or emergency reduction of gas or fluid pressure within a closed metal vessel or piping system. It is mainly used to prevent equipment rupture or vessel failure when exposed to extreme external heat or process abnormalities.
Depth – It is the perpendicular distance measured downward, inward, or backward from a surface or reference plane. It is a critical spatial dimension used to calculate volumes, ensure structural integrity, and define the machining specifications of manufactured parts.
Depth filter – It is a filtration medium which captures and retains particles throughout its entire three-dimensional internal structure rather than just on the outer surface. Fluid moves through a thick, tortuous maze of fibres or porous matrix, trapping contaminants through mechanical sieving and inter-molecular forces.
Depth image-based rendering – It is a technique used to create virtual view-points by displacing pixels and objects from a reference view based on their disparity, which is inversely related to depth. This method accounts for the varying movement of foreground and background objects when transitioning between camera views.
Depth of a cavity – It is the vertical or axial measurement from the outer surface, rim, or opening of a hollowed-out space down to its lowest internal point or base.
Depth of cut – It is the thickness of material removed from a work-piece in a single machining of the part.
Depth of discharge – It is the percentage of a battery’s total capacity which has been used or removed during a discharge cycle. It is the direct opposite of the state of charge (SoC). Together, they always add up to 100 %.
Depth of field – It is the depth in the subject over which features can be seen to be acceptably in focus in the final image produced by a microscope.
Depth of fusion – It is the distance which the fusion extends into the base metal or previous pass from the surface melted during welding.
Depth of penetration – In various analytical techniques, it is the distance the probing radiation penetrates beneath the surface of a sample.
Depth profile – It is an analytical measurement of a material’s chemical composition, physical properties, or structure as a function of distance from its outer surface downward into the bulk. It helps engineers see how properties change layer by layer in thin films, semi-conductors, and treated metals.
Depth profiling – It is a technique aimed at determining the local composition of a material as a function of depth beneath the surface, typically by measuring the intensity of a signal over time and converting this into a composition-depth relationship. This process needs calibration and consideration of different factors affecting the relationship between sputtering time and depth.
Depth ratio – It normally refers to the span-to-depth ratio (or its inverse, the depth-to-span ratio). It is a dimensionless geometric index used in structural design to relate a member’s length or span to its cross-sectional depth. This ratio controls structural stiffness, prevents excessive deflection, and avoids failure under load.
Derailment – It is an incident where a train’s wheel or set of wheels leaves the running surface of the rail. This structural failure disrupts the vehicle-track interaction and can stem from mechanical faults, bad track geometry, or excessive forces.
Derating factor – It is a multiplier (ranging from 0 to 1) applied to the nominal or name-plate rating of a piece of equipment or component. It reduces the maximum allowable operational capacity to account for harsh real-world environmental or installation conditions which prevent proper heat dissipation or stress management.
Deration – It is also called derating. It is the intentional reduction of a device or system’s operating capacity. Engineers do this to keep equipment safe, stop overheating, and make parts last longer when working in harsh real-world conditions.
Derby – It is a large, typically cylindrical piece of primary metal produced during a bomb reduction process. Weighing anywhere from 45 kilograms to over 100 kilograms, these blocks serve as raw ingots which eventually undergo further processing or refining into specific metal alloys.
Derivative – It is an image created from the master image, through some kind of image editing process to create a user or working copy. The process normally involves a loss of information to reduce the size by sampling it to a lower resolution, using lossy compression techniques, or altering an image using image processing techniques. Typically, derivatives are made for purposes such as web access, including ‘thumbnail’ images, or as ‘reference’ or ‘service’ images which can fit completely within an average monitor.
Derivative action – It is a control-system mechanism which calculates the rate of change of an error signal over time. Acting as the ‘D’ term in a PID (proportional-integral-derivative) controller, it predicts future errors, adds system damping, and reduces overshoot or oscillations near a target setpoint.
Derivative causality – In system dynamics and modeling like bond graph modelling method, it occurs when an energy-storing element’s output is to be differentiated with respect to time to find its input, meaning the system equation requires a time derivative rather than an integral.
Derivative control – It is a component of a PID (proportional-integral-derivative). controller that calculates the rate of change of an error signal over time. It predicts future system behaviour, applies a braking or dampening effect, and reduces over-shoot or oscillations to stabilize dynamic engineering systems.
Derivative controller – It is a feedback control component which reacts to the speed and direction at which a system’s error changes. Its output matches the time rate of change of that error. It predicts future trends to slow down sudden shifts, reduce bouncing, and steady the system.
Derivative element – It is a component or mathematical operator which outputs a signal proportional to the rate of change (the time derivative) of its input. It reacts to how fast a value changes rather than its absolute level.
Derivative gain – It is the proportional constant which determines the quantity of derivative control action in a PID (proportional-integral-derivative) controller, adjusting the controller output based on the rate of change of the error signal to prevent overshoot or undershoot of the set point. It is the multiplier in a PID (proportional-integral-derivative) controller which scales the rate of change of the error signal. It predicts future errors, dampens system oscillations, and reduces overshoot by reacting strongly when the process value changes fast.
Derivative gas turbine – It is frequently called an aero-derivative. It is an engine originally designed for aircraft propulsion that has been modified to run stationary industrial, electrical, or marine equipment.
Derivative operation – It is the mathematical process of finding the instantaneous rate of change of a dependent system variable with respect to an independent variable (like time or position). It defines system dynamics, slope gradients, and transient behaviours.
Derivative operator – It is a mathematical symbol or rule, which instructs an system or equation to take the instantaneous rate of change of a physical variable. It transforms a function representing a signal, field, or motion into its rate of change.
Derivative spectrum – It is the first- or higher-order mathematical derivative of an absorbance or transmission signal with respect to wave-length or frequency. It is used as a signal-processing tool to sharpen peak positions, resolve overlapping spectral bands, and eliminate background baseline drift.
Derivative term – It very frequently refers to the rate-of-change component (D) in a PID (proportional-integral-derivative) controller, which predicts future error trends based on the slope of the error over time to reduce overshoot and dampen system oscillations.
Derived aggregates – These are frequently recycled or manufactured aggregates. These are granular materials got by processing secondary waste streams, industrial by-products, or recycled construction debris rather than direct quarrying of natural rock.
Derived bitumen – It is a heavy, viscous hydro-carbon binder got mainly as a high-boiling residue from the fractional and vacuum distillation of crude oil, or extracted from natural deposits like oil sands. It acts as a main adhesive and waterproofing agent.
Derived carbon material – It is a specialized substance created by transforming precursor compounds, such as polymers, bio-mass, or metal carbides, into a predominantly pure carbon structure through thermal, physical, or chemical processes. These engineered carbons feature tailored pore sizes, high surface areas, and specific crystal arrangements.
Derived dimension – It is a physical quantity or drawing measurement calculated or compounded from base fundamental units (like mass, length, and time) or other primary geometric dimensions on a blue-print.
Derived electricity – Electricity derived refers to electrical power produced by converting primary energy sources, such as coal, natural gas, nuclear fission, hydro, wind, or solar, into a secondary, usable energy form. It refers to the generation of electrical power from different sources, including coal, natural gas, hydro, nuclear, solar, and wind energy, with the composition of a country’s electricity grid reflecting its reliance on these sources. The environmental impacts associated with electricity generation can vary considerably depending on the mix of energy sources utilized.
Derived fuel – It is very frequently known as refuse-derived fuel (RDF). It is a specialized fuel produced by sorting, processing, and treating combustible waste materials, such as non-recyclable plastics, paper, cardboard, and wood, to achieve a high and uniform calorific value.
Derived property – It is a characteristic of a material or system which is calculated or deduced from fundamental physical measurements rather than being measured directly. For example, yield strength is derived from a force-displacement test, and Poisson’s ratio is derived from lateral and axial strain.
Derived requirement – It is a necessary condition, constraint, or interface specification which is not explicitly stated in the initial stakeholder or parent requirements, but emerges as an implicit consequence of the chosen design architecture, technology, or preliminary solution.
Derived SI (The International System of Units) units – These are measurement units formed by multiplying, dividing, or powering the seven fundamental base units (meter, kilogram, second, ampere, kelvin, mole, and candela). These n engineering, they ensure global standardization and dimensional consistency across mechanics, thermodynamics, and electrical systems.
Derived standards – In the SI (The International System of Units) system, there are seven basic measurement units as given in Tab 1.
| Tab 1 SI Base Units | |||
| Sl. No. | Base quantity | Name of Base Unit | Symbol |
| 1 | Length | meter | m |
| 2 | Mass | kilogram | kg |
| 3 | Time | second | s |
| 4 | Electric current | ampere | A |
| 5 | Thermodynamic temperature | kelvin | K |
| 6 | Amount of substance | mole | mol |
| 7 | Luminous intensity | candela | cd |
All of the other units are derived from the seven basic units. Tab 2 lists the most common derived SI units, together with the base units which are used to define the derived unit. As an example, the unit of frequency is the hertz which is defined as the reciprocal of time, i.e., 1 hertz (1 Hz) is one cycle per second.
Derived unit – It is a unit of measurement made by combining the seven fundamental base units (meter, kilogram, second, ampere, kelvin, mole, and candela) through multiplication, division, or powers.
Derived value – It is a calculated metric representing the ratio of a product’s essential function to its total life-cycle cost. It serves to measure whether a design delivers necessary performance and reliability at the most economical overall cost.
Derjaguin approximation – It is also called proximity approximation. It relates the force acting between two curved, finite-sized bodies to the interaction energy between two flat, parallel planar walls. It simplifies complex nano-scale and colloidal force calculations.
Derjaguin–Broekhoff–de Boer (DBdB) model – It is a classic thermodynamic framework used in chemical and materials engineering to describe gas adsorption, multilayer film formation, and capillary condensation or evaporation within meso-porous and macro-porous materials.
Derjaguin-Landau-Verwey-Overbeek (DLVO) framework – It is a cornerstone theory in colloidal science. It explains the stability of particle dispersions in liquid by calculating the net interaction energy between them, which is derived by summing the attractive van der Waals forces and the repulsive electrical double-layer forces.
Derjaguin-Muller-Toporov (DMT) model – It is a contact mechanics theory used in engineering and tribology to evaluate elastic contact and adhesion between a solid sphere and a flat surface. It assumes that the contact profile remains Hertzian, while attractive adhesive forces act exclusively in the annular region just outside the contact area.
Dermatitis – It is an inflammation of the skin, which can be caused by allergy to certain casting adjuncts, such as resins, particularly in the shell process.
Derrick barge – It is a specialized floating marine vessel equipped with a high-capacity crane (derrick) used for heavy lifting, structural installation, and offshore construction in oceans, rivers, and harbours.
Desalination – It is a process which removes mineral components from saline water. More generally, desalination is the removal of salts and minerals from a substance, e.g., soil desalination. The by-product of the desalination process is brine. Modern interest in desalination mostly focuses on cost-effective provision of fresh water for human consumption. Along with recycled waste-water, it is one of the few water resources independent of rainfall. Because of its energy consumption, desalinating sea water is normally more costly than fresh water from surface water or groundwater, water recycling and water conservation. Desalination processes are using either thermal methods (in the case of distillation) or membrane-based methods (e.g., in the case of reverse osmosis).
Desalination applications – These refer to the processes which utilize desalination to remove dissolved salts and minerals from saline water, primarily to produce freshwater for drinking, irrigation, or industrial use. Additionally, these applications can involve the recovery and reuse of brine or concentrated feed in certain industrial contexts, where it can hold substantial value.
Desalination membrane – It is a specialized semi-permeable physical barrier, typically a thin polymer film like aromatic polyamide, which allows water molecules to pass through while rejecting dissolved salts, ions, and impurities under mechanical or thermal driving forces.
Desalination plant – It is an industrial water treatment facility which converts saline ocean or brackish water into safe, potable fresh water or low total dissolved solids (TDS) water by stripping out dissolved salts and impurities using advanced membrane or thermal processes.
Desalination pre-treatment – It is the physical, chemical, and biological processing of raw feed water before it reaches core separation units like reverse osmosis membranes. Its main engineering goal is to remove suspended solids, organics, and scale-forming minerals to prevent membrane fouling, reduce downtime, and extend equipment life.
Desalination, renewable energy – Renewable energy desalination (RED) refers to the integration of renewable energy sources, such as solar, wind, and geothermal, into desalination processes to reduce carbon emissions and improve sustainability. It can utilize thermal, electrical, or mechanical energy from renewable sources to power desalination systems, with solar energy being the most extensively studied option because of its adaptability and high availability in water-stressed regions.
Desalination system – It is an industrial process which removes dissolved salts and minerals from seawater or brackish water to produce safe, potable fresh water. It relies on mechanical, thermal, or chemical separation methods to address municipal and industrial water shortages.
Desalination technology – It is an artificial process which removes dissolved salts and minerals from saline water (such as seawater or brackish groundwater) to produce safe, potable fresh water for drinking, agriculture, or industrial use.
Desalination unit – It is an industrial system which removes dissolved salts and minerals from seawater or brackish water to output clean, low-salinity freshwater. It splits a saline feed stream into two outputs namely purified product water and a concentrated brine by-product.
Desander – It is a mechanical solids control device used in oil and gas drilling, trenchless construction, and water treatment, to separate abrasive sand, silt, and coarse solid particles from drilling fluids or slurries.
Descale – It is the process of removing the brittle oxide layer (known as ‘scale’ or ‘fire scale’) which forms on the surface of hot-worked or heat-treated castings. This is typically done to achieve a smooth surface and prepare the metal for machining, inspection, or coating.
Descaling – It is removing the thick layer of oxides formed on some metals at high temperatures. It is also a chemical or mechanical process for removing scale or investment material from castings.
Descaling equipment – It is placed before the mill after the reheating furnace. High pressure water is sprayed onto the surface of the hot rolling stock steel to remove the scale. The equipment required for this process basically consists of a high-pressure pump, powered by an alternating current motor, which can be controlled by a variable speed drive. High pressure pump supplies water through specifically designed header and nozzles, which are directed at the hot steel. The removal of scale takes place due to the combined action of the water pressure and the rapid cooling of the steel.
Descent direction – It is a vector which satisfies the inequality condition indicating that a small move in that direction decreases the cost function, hence ensuring movement toward a minimum point in the iterative optimization process.
Describing function – It is a method for analyzing non-linear control systems.
Descriptive – In data analysis, it is an analysis method which summarizes the data to reach a simple presentation as a result. This method can be categorized into (i) univariate analysis, and (ii) bivariate analysis.
Descriptive criterion – It is a specific, qualitative or quantitative parameter used to describe, characterize, or evaluate system states, material limits, or design performance without prescribing exact proprietary methods. It sets the baseline properties needed for an item or model.
Descriptive label – It is a piece of metadata or an explicit target variable that provides comprehensible, human-readable meaning to data. It explains a dataset’s characteristics, context, or ground-truth ‘answer’, making it uniquely suited for consumption by down-tream artificial intelligence (AI) and machine learning (ML) systems. In quality control and automated visual inspection systems, descriptive labels identify specific defects on a production line.
Descriptive statistics – It is the body of statistical techniques concerned with describing the salient features of the variables used in one’s study. If one has a large set of data, then descriptive statistics provides graphical (e.g., boxplots) and numerical (e.g., summary tables, means, quartiles) ways to make sense of the data. The branch of statistics devoted to the exploration, summary, and presentation of data is called descriptive statistics. If people need to do more than descriptive summaries and presentations, they are to use the data to make inferences about some larger population. Inferential statistics is the branch of statistics devoted to making generalizations.
Desertification – It means land degradation in arid, semi-arid, and dry sub-humid areas resulting from different factors including climatic variations and human activities is known as desertification. The progressive destruction or degradation of vegetative cover, especially in arid or semi-arid regions bordering existing deserts.
Desiccant – It is a hygroscopic substance which is used to induce or sustain a state of dryness (desiccation) in its vicinity. Normal encountered pre-packaged desiccants are solids (e.g., silica gel, and calcium oxide) which absorb water. Desiccants for specialized purposes can be in forms other than solid, and can work through other principles, such as chemical bonding of water molecules. Industrially, desiccants are widely used to control the level of water in gas streams.
Desiccant bed – It is a packed or fixed volume filled with porous, hygroscopic granules, such as silica gel, activated alumina, or molecular sieves, used to strip moisture out of air or process gases through adsorption or absorption.
Desiccant cooling system – It is an HVAC (heating, ventilation and air conditioning) technology which controls air humidity by using moisture-absorbing materials (desiccants) instead of relying solely on standard refrigeration vapour-compression. It separates humidity control from temperature control, using thermal energy or low-grade waste heat to dry and recycle the desiccant.
Desiccant wheel – It is a porous, slowly rotating rotary dehumidifier coated with a moisture-adsorbing material (such as silica gel, molecular sieve, or activated alumina). It continuously extracts water vapour from process air streams through mass transfer and discharges it using a heated reactivation air sector.
Design – It is the concept of or proposal for an object, a process, or a system. The word design refers to something which is or has been intentionally created by a thinking agent, and is sometimes used to refer to the inherent nature of something, i.e., its design. The verb to design expresses the process of developing a design.
Design accelerator – It is a built-in CAD (computer-aided design) toolset which automates the creation, calculation, and sizing of standard mechanical components based on functional engineering requirements.
Design action – It is a single, observable, and quantifiable step within a design process, such as defining a requirement, building a prototype, or running a simulation test. Sequences of these actions form structured strategies used to solve complex technical problems.
Design activity – It is the formal specification of tasks, objectives, and constraints needed to transform a functional need into a manufacturable or operational system, component, or process. It outlines the scope of creative, analytical, and evaluative steps undertaken by design engineers.
Design advisor – Design advisor a senior expert or specialized decision-support system which guides project teams on design quality, manufacturing feasibility, and regulatory standards. Design advisors review blue-prints, optimize material selection, and mitigate structural or functional risks before production.
Design allowables – These are statistically determined materials property values which are derived from test data. They are limits of stress, strain, or stiffness which are allowed for a specific material, configuration, application, and environmental condition. The selection of appropriate design allowables for structures composed of composite materials is necessary for the safe and efficient use of these materials.
Design allowance – It is an intentional, pre-determined difference between exact theoretical dimensions and manufactured parts, or an added safety / material buffer. It ensures proper mechanical fits (like clearance or interference between a shaft and a hole), accounts for material removal during machining, or covers operational uncertainties.
Design alternatives – These are different proposed solutions or system configurations created to meet specific functional requirements. Engineers build and compare these options using trade studies, cost analysis, and performance metrics to select the best choice before final production.
Design analysis – It is the systematic process of using mathematics, physics, and scientific principles to evaluate a proposed or existing system, component, or product. It tests whether a design meets performance, safety, and operational requirements before physical creation.
Design and engineering – It consists of the task of translating a set of functional requirements of the project into a full set of specifications and drawings providing the details needed. It involves a variety of special fields which include (i) process engineering, (ii) civil engineering, (iii) structural engineering, (iv) mechanical engineering, (v) electrical engineering, (vi) fluid engineering, (vii) instrumentation and control engineering, (viii) automation and control activities, (ix) geo-technical engineering, and (x) environmental and safety engineering etc.
Design and environment – It is frequently framed as design for environment (DfE) or environmental engineering design. It is a systematic practice which integrates ecological health, resource conservation, and life-cycle sustainability into the creation of products, structures, and technological systems.
Design appraisal – It is a procedure by which a certifying authority appointed by the purchaser, appraises the design parameters of the equipment and / or materials he is buying. The supplier is required to submit drawings, calculations and documents as required to the certifying authority in conjunction with those normally needed for review and acceptance by the purchaser.
Design approach for equipment foundation – The task for designing of foundations for equipments with dynamic loads in addition to the normal data on the equipment is to contain (i) the technical characteristics of the equipments (name, type, number of rotations per minute, power, and total weight, etc.), (ii) information about the magnitudes, places of application, and directions of action of static loads, as well as about amplitudes and frequencies, places of application, and direction of dynamic loads, (iii) data on the maximum permissible deformations of the foundations and their basement, (iv) requirements for placement of equipment on the foundations, (v) drawings of the dimensions of the foundation within the location of the equipment, fasteners, as well as auxiliary equipment, communications, and hole sizes, (vi) drawings of all communications adjacent to the foundation, (vii) data on the geological conditions of the construction site and soil properties, (viii) information about the location of the designed foundation relative to the nearest structures, and (ix) requirements for the protection of the foundation from ground-water, as well as other external factors characteristic of the design environment.
Design approval – It is the formal, documented authorization by an authorized engineer, review board, or regulatory body confirming that a technical design meets all specified functional, safety, quality, and legal requirements before transitioning to production or construction.
Design aspect – It is a specific feature, component, or characteristic which makes up a broader creative or technical plan. It highlights an individual element, such as visual style, functional utility, or structural layout, which creators evaluate and refine during the design process.
Design aspects of dies– These aspects include die clearance, material selection and flow, forces and tonnage calculations, guiding and stripping, and ejection and cooling.
Design assembly drawing – It is an assembly drawing or a design layout which is first drawn when an equipment is designed to clearly visualise the performance, shape, and clearances of different parts comprising the equipment.
Design assessment – It is also called design evaluation. It is the critical examination of design processes and outcomes to improve value and effectiveness through methodologies such as function analysis and process simplification. It is the systematic process of analyzing a product, system, service, or educational plan to determine how well it meets its intended functional, aesthetic, and usability goals. It reviews structural and visual choices against explicit standards or learning outcomes.
Design assurance level – It is a safety-critical classification used in industry. It defines the rigorousness of the design, testing, and verification processes needed for software and hardware. Levels range from A (most critical) to E (least critical) based on the potential failure effect on an equipment.
Designated accrediting authority – It is a senior official or executive responsible for formally authorizing an information system to operate. They explicitly accept the residual security risks to the organization, its mission, and its assets, issuing an authority to operate (ATO).
Designated approval authority – It is a formal, legally recognized role given to an individual or organization to certify compliance, approve technical designs, or sign off on operational safety. The authority possesses the vested power to accept the risk of a system or product on behalf of an organization or regulatory body.
Designated authority – It is the specific organization or certified individual officially responsible for approving design requirements, maintaining the design basis, and clearing design changes. This authority ensures all structures or systems are safe, compliant with technical specifications, and fit for operation.
Designated target – It is frequently called datum target. It is a specific point, line, or area on a part’s surface used to establish repeatable reference frames (datums) for manufacturing, inspection, and tooling. It is important for irregular, moulded, cast, or sheet metal components.
Designation – It refers to an alphanumeric code or symbolic label used to explicitly identify components, materials, or technical elements. Baseline designations provide standardized communication across planning, drafting, and manufacturing, preventing ambiguity in material properties, product roles, or technical requirements. It is also an official job title which defines an employee’s specific role, level of authority, and position within the organizational hierarchy. Clear designations ensure role clarity, determine reporting structures, and establish a base-line for compensation and career progression.
Designation system – It is a standardized coding method used by engineers and manufacturers to classify metallic materials. These systems use alpha-numeric combinations to identify an alloy’s generic family, exact chemical composition, mechanical properties (such as yield strength), and heat-treatment conditions. Since metals with even slight variations in composition behave differently, these globally recognized codes ensure safety, quality control, and consistency in manufacturing.
Design authority – It is the designated person, board, or corporate body responsible for maintaining the technical integrity, fitness for purpose, and regulatory compliance of an engineered system. Design authority acts as the ‘gatekeeper’ and technical leader, ensuring all changes adhere to original design intent and safety standards.
Design base-line – It is a formally approved and documented set of specifications representing the initial configuration of a system. It acts as a reference point to measure progress, control changes, and ensure all development aligns with original requirements. It serves as the reference point for all future development, testing, and modifications, ensuring that any changes undergo rigorous configuration management before implementation.
Design basis – The set of requirements which bound the design of systems, structures, and components within the facility. These design requirements include consideration of safety, plant availability, efficiency, reliability, and maintainability. Some aspects of the design basis are important for safety, although others are not.
Design basis accident – It is a postulated accident leading to accident conditions for which a facility is designed in accordance with established design criteria and conservative methodology. It is also a postulated accident which a nuclear facility is to be designed and built to withstand without loss to the systems, structures, and components necessary to ensure public health and safety.
Design-bid-build – It is a traditional project delivery method in engineering and construction defined by three sequential phases namely design, bid, and build. The owner hires a designer first to make plans, opens the project for contractor pricing, and then hires a separate builder to construct it.
Design boundary – It is the explicit limit or scope which defines what is included inside a system, product, or project and what stays outside in the environment. It sets clear edges for engineering work, software features, or physical dimensions.
Design-build – It is a project delivery method where a single entity provides both architectural / engineering design and construction services under one contract. This contrasts with traditional methods by using a single point of responsibility to streamline communication, reduce costs, and accelerate timelines.
Design-build method – It is a project delivery system where an owner signs a single contract with one unified team for both the architectural / engineering design and the physical construction. It combines the roles of designer and contractor into one entity, facilitating time and cost savings, reducing change orders, and shifting design liability from the owner to the contractor. This approach allows for concurrent construction and design activities, resulting in improved project efficiency.
Design, cache – Cache design is a high-speed temporary data storage layer that keeps copies of frequently used data. It reduces access time, lowers backend database load, and speeds up system performance by serving requests from fast memory instead of slow disks.
Design calculation – It is a mathematical and scientific process used by engineers to determine physical dimensions, material properties, and safe operating limits for a system or component. It ensures that structures and products function correctly and safely under expected load conditions.
Design certification – It is an official approval or professional credential confirming that a specific physical product, structural plan, engineering system, or individual designer meets established safety, quality, and regulatory standards. Depending on the context, the term normally splits into two major categories namely regulatory / technical approval of a blueprint or product, and professional credentials for individual practitioners.
Design characteristics – These are the measurable attributes and physical features of a product or system which fulfill functional requirements and constraints. They translate subjective customer needs into quantifiable engineering specifications (e.g., exact dimensions, material properties, electrical limits, and tolerances). These characteristics form the core foundation of product development and are normally categorized based on their impact on safety, function, and assembly.
Design choice – It is a deliberate selection made between alternative ways to fulfill a project, product, or engineering requirement. It shapes how a system functions, looks, or performs by balancing user needs, technical limits, and resource constraints.
Design code – It is a set of rules or regulations which tell the designer what to do and when and under what circumstances. While codes are frequently developed by technical or professional groups, they frequently are adopted by governmental jurisdictions and become legal requirements. Examples are the building code for the structural safety of buildings and the fire code.
Design competition – It is a contest where an organization, government, or client asks individuals or teams to submit creative proposals or plans based on a specific project goal, theme, or set of rules. An expert panel or jury then judges the entries to choose a winner.
Design complexity – It refers to the level of intricacy and sophistication involved in the design of a system or application. It is the measure of how many parts a system has, how those parts link together, and how hard it is to make or run the system. It covers the number of choices, rules, and moving pieces inside software, engineering models, or visual layouts.
Design concept – It is the abstract construct or plan for a product or system, representing the organization and structure of its elements as conceived by the designer. It describes how a product is intended to be executed or constructed, rather than its physical instantiation.
Design considerations – These are the core rules, user needs, and limits which guide how designers build a product, system, or space. Key factors include functionality, safety, and cost.
Design constant – It is a fixed, unchanging value or parameter established early in a project phase. It guides engineering, software development, or system architecture to ensure consistency, safety, and easy maintenance.
Design constraint – It is a design parameter (variable) which is required to fall within a fixed range of values.
Design control – It is a formal set of quality practices and procedures used to plan, document, and manage product development. The key phases include design planning, design inputs, and design outputs. They are very frequently needed by regulatory bodies to ensure safety and effectiveness.
Design control drawing – It discloses the basic technical information and performance requirements necessary for a contractor to complete the detailed design required to develop and produce an item. The drawing in itself does not provide complete design for which a detailed design drawing is needed. It includes those details which are necessary to develop the detail design of the item such as (i) configuration, mounting, mating, and other necessary dimensions, (ii) performance, installation, reliability, and interchangeability requirements, (iii) test requirements, (iv) schematic, connection, or other appropriate diagram (if electrical, electronic or other circuitry is involved), (v) the mating connections, their location, and a connection diagram, and (vi) reference to other documentation.
Design criterion – It is a specific, measurable standard or requirement which a product, system, or service is required to meet to be considered successful. Design criteria are the specific attributes, limits, and guidelines an engineered system is required to meet to solve a problem. These turn general goals into clear rules. Teams use these rules to guide choices and test new ideas.
Design current density – It is the target or maximum electric current per unit cross-sectional area used by engineers to plan safe, reliable systems. It prevents overheating, voltage drops, and material breakdown in components like wires, circuit traces, and cathodic protection grids.
Design cycle – It is a step-by-step method used to solve problems and make new products. It has four main parts namely investigating or planning, developing ideas, creating the solution, and evaluating the results. Since it is a continuous loop, designers can repeat the steps any-time to make their work better.
Design, data – Data design is the process of creating a blueprint for how data is structured, stored, and accessed within a system. It focuses on defining data types, relationships, and storage mechanisms to ensure information remains accurate, secure, and easy to use.
Design day – It very frequently refers to the extreme weather conditions used to size heating and cooling systems. It can also mean a dedicated day for creative project work or a global observance honoring the design profession.
Design decision-making – It is the cognitive and strategic process of choosing a preferred path among multiple alternatives during a creation or planning phase. It blends user research, organizational goals, and technical limits to solve problems.
Design defect – It is an aspect of a design or product which causes it to fail to perform as safely or reliably as an ordinary consumer expects.
Design development – It is the middle project phase where rough ideas and basic sketches turn into clear, detailed, and practical plans. It sits right between early conceptual design and final technical construction blue-prints.
Design display – It means the strategic planning and physical or digital creation of visual presentations to showcase products, information, or art. It combines spatial layout, lighting, and branding to grab user attention and communicate a clear message.
Design document – It is a written blue-print which explains what a project is, how it will work, and why specific choices have been made. Key components typically include project goals, system architecture, and alternative approaches considered.
Design domain – It is the specific subject area, real-world environment, or problem space which a system, product, or software is built to address. It defines the boundaries, rules, and specialized language used to shape effective solutions.
Design drawing – Design drawing is made during the initial stages of the project and used for all initial activities including contract bidding. Design drawings are subject to revision with the progress of the project. Design drawing is used to develop and communicate ideas about a developing design.
Design duty – It is the legal or professional obligation of a person or an organization to create plans, specifications, or structures which meet needed standards of safety, quality, and performance.
Design earthquake – It is a specific level of ground shaking and seismic force defined by engineering standards. Buildings and structures use this level to ensure safety and prevent collapse during expected local seismic events.
Designed experiment – It is normally called design of experiments (DOE). It is a structured, mathematical method for planning and running tests. It lets engineers change multiple input factors at the same time to see how they affect a final output or response. Instead of changing only one thing at a time, design of experiments finds the true causes and hidden interactions between different variables quickly and efficiently.
Designed flow rate – It is also called design flow rate. It is the target capacity or maximum fluid volume per unit of time which a system, pipe, pump, or treatment plant is engineered to handle safely and efficiently. It ensures proper operation under peak expected demand without system overloads.
Designee – Designee is an individual or organization officially authorized or appointed by a governing body to act on its behalf, specifically to examine, test, and approve compliance data.
Design engineer – Design engineer is a hybrid professional who bridges the gap between creative design and technical engineering. Design engineers are responsible for conceptualizing, developing, and refining products, systems, or structures—ensuring they are both aesthetically functional and practically manufacturable. Design engineers are the driving force behind taking an idea from the drawing board to the production floor.
Design engineering – It is a cross-disciplinary field which combines the creative problem-solving of design with the technical and scientific rigour of engineering. It focuses on turning conceptual ideas into functional, safe, and manufacturable products or systems.
Design environment – It is a connected work-space or set of tools, rules, and software which lets creators build products, systems, or digital worlds. Depending on the field, it means physical spaces, computer systems, or green production rules.
Design equation – It is a mathematical formula derived from physical laws, material limits, or statistical data which engineers and scientists are using to calculate safe, functional dimensions, capacities, or operational parameters for a system or component.
Designer – Designer is a professional who translates scientific principles and creativity into practical products, systems, or structures. Designers bridge the gap between abstract concepts and functional reality, focusing on prototyping, testing, and refining solutions while navigating technical and physical constraints.
Designer note – It a documented annotation, rationale, or instruction added by an engineer or designer to blue-prints, schematics, or CAD (computer-aided design) models to clarify intent, specify tolerances, or guide manufacturing.
Designer’s check-list – It is a systematic quality-assurance tool which ensures all critical parameters, safety regulations, and client specifications are met before a product or system moves to prototyping or production. It compensates for human memory limitations to prevent costly errors and oversights.
Designer solvent – It is a custom-tailored fluid, such as an ionic liquid or a deep eutectic solvent, whose physical and chemical properties can be precisely adjusted at the molecular level to fit a specific engineering or industrial process.
Designer surface – It typically refers to a precise, mathematically defined outer boundary or skin of a 3D model created through surface modelling, or a specially engineered material surface tailored for a specific functional performance.
Design evolution – It is the gradual process where a product, system, or artifact changes and improves over time. It happens through small, repeated updates based on user feedback, new technology, and changing needs.
Design factor – It is the quantity of lifting value a magnet is labelled against the lifting value under ideal conditions. Ideal conditions are when a magnet is new and pulled off a newly machined, thick, low carbon steel plate. The kilograms of pull it takes to break the magnet away from the steel surface is the ‘maximum’ lifting value. Design factor (de-rating) values are then determined by taking this maximum lifting value and dividing it by the manufacturers design factor. Design factors are minimum 2:1 and in the majority of cases 3:1.
Design factor of safety – It is a numerical ratio indicating how much stronger a structure, component, or system is designed to be compared to the maximum load it actually experiences in normal operation. The fundamental purpose of incorporating a design factor is to ensure a product or structure remains safe, functional, and intact under extreme or unforeseen conditions. It provides a buffer against uncertainties like material defects, wear and tear, manufacturing variances, and unexpected dynamic forces.
Design failure mode and effects analysis – It is a methodology which is used by design engineers to make sure products are designed the best they can be. In other words, design failure mode and effects analysis is used to keep the number of failures caused by a design as low as possible, as well as to ensure that the product is working as intended. Effective design failure mode and effects analysis lets teams optimize their designs deliver high-quality, safe products and ensure the highest quantity of satisfaction for the end users.
Design features – These are the elements which comprise a part, such as walls, holes, and grooves, and the solid elements, such as rods, cubes, and tubes.
Design flood – It is a hypothetical or statistically calculated flood event, expressed as a peak discharge rate or a full flood hydrograph, used as the definitive basis for planning, sizing, and engineering structural components like dams, spillways, bridges, and drainage systems.
Design flow-chart – It is a visual diagram which maps out the steps, tasks, and decisions of a process or system. It uses shapes like boxes and diamonds connected by arrows to show the exact order of work from start to finish.
Design flow rate – It is the target capacity or maximum amount of fluid (liquid or gas) a system is planned to safely and efficiently handle under peak or future operational limits. It dictates the sizing of pipes, pumps, and treatment plants.
Design for assembly – It is a methodology for examining the assembled parts of a product in terms of the time and cost for assembly of each part. The overriding strategy is to produce an acceptable design with the minimum number of parts.
Design for disassembly – It is a methodology for designing a product so that it can be economically disassembled and the material from which the individual parts are made can be recovered and reused.
Design for function and fit – It is an expression which exemplifies the two central rules of design namely (i) first and foremost, the design is to perform the function for which it is intended, and (ii) the design is to be designed to tolerances appropriate to the application.
Design for manufacturability – It is the engineering practice of incorporating manufacturing considerations during the design phase to anticipate and address potential manufacturing issues, ultimately leading to long-term cost savings during production.
Design for manufacture It is also called design for manufacturability (DFM). It is an approach toward integrating the product and process concepts so that the best match is made between product and process requirements. Design for manufacture includes detailed examination of the design so that it is most easily and inexpensively manufactured by the intended process.
Design format – It is the overall physical or digital framework, size, shape, and structure which defines the spatial limits of a visual composition or file. It sets the basic boundary, like an artist’s canvas, screen ratio, or file type, before any layout or creative elements are added.
Design for recycling – It is a product design approach which focuses on making items and packaging easy to sort, take apart, and process at the end of their life. The goal is to keep materials pure and valuable so they can re-enter the production cycle instead of going to waste.
Design for reliability – It is a proactive engineering process which ensures a product or system performs its intended function without failure under stated conditions for a specified period. Instead of fixing issues after production, design for reliability (DfR) builds reliability directly into the product during the early design phase.
Design for remanufacture – It is an engineering approach which plans for a product’s end-of-life recovery during the initial design phase. It ensures a used product can be easily disassembled, cleaned, repaired, and reassembled into a like-new condition with equal or better performance.
Design for testability – It is a methodology which embeds special test features, hardware structures, or software hooks directly into a product’s architecture during the design phase. These additions make it easier, faster, and more cost-effective to detect, diagnose, and isolate manufacturing defects or functional faults post-production.
Design for the environment – It is a design methodology in which environmental factors are considered of equal importance to performance factors. It is sometimes called green design.
Design for ‘X’ – It is a catch phrase which describes the understanding that engineering designs increasingly are to be consciously designed for factors other than function and tolerances. These issues include design for assembly, design for manufacture, and design for installation, maintenance, safety, and disposal etc.
Design function – It is the specific purpose, role, or practical task which an object, system, or software component is created to perform. It defines what a design is required to do to satisfy user needs and solve a core problem, separating practical utility from visual aesthetics.
Design generator – It is also called generative design system. It is a tool or software which uses rules, algorithms, or artificial intelligence to automatically create visual, structural, or statistical layouts. People give it a goal, material choice, or set of rules, and it builds options for the people.
Design guidance – It is a set of recommendations, rules, and best practices used to direct the creation of products, systems, or software. It helps teams maintain high quality, usability, and visual consistency across different platforms.
Design guide – It is a set of rules, standards, and best practices which help creators make clear, uniform, and user-friendly products, buildings, or digital interfaces. It acts as a shared reference manual to keep quality and style steady across a project.
Design guidelines – These are defined as standardized recommendations which promote manufacturability, quality, and reliability in engineering. They provide specifications on features, tolerances, supports, and orientations to optimize production and minimize defects, ultimately improving efficiency and part quality.
Design history – It is a permanent chronological record documenting why and how design decisions and project iterations have been made over time. It is a compilation of records which describes the design process of a finished product, including elements such as design plans, inputs, outputs, reviews, verifications, validations, transfers, product releases, and design changes. It is important for ensuring compliance with regulatory standards in the development of several products.
Design information – It refers to the structured data and knowledge generated during the structural design process, encompassing aspects such as conceptual design, modelling, analysis, detailing, drafting, and costing, which collectively support the planning and execution of construction projects.
Designing and implementing record-keeping systems – It refers to the structured process of creating and deploying policies, procedures, and technological tools to capture, maintain, and access organizational records across their entire life-cycle, from creation through to archival or defensible disposal.
Design integrity – It is the essential aspect of process safety management (PSM), ensuring that the design of a plant, such as a refinery or petrochemical unit, is robust and incorporates multiple layers of protection from the initial design stage to achieve uninterrupted safe and reliable operations. It means keeping a product or structure true to its original vision, purpose, and quality from start to finish. It ensures that form, function, and materials work together honestly without losing quality during production or use.
Design intent – It is a general term used with respect to describing and documenting the aspects of some part of the design which are crucial to the success of the design.
Design issues – These are open-ended, complex problems encountered during product or system development.
Design iteration – It is a cyclical process of prototyping, testing, analyzing, and refining a product or concept. Instead of aiming for perfection on the first try, teams use repeated loops of feedback to make continuous, step-by-step improvements.
Design joint – It the planned configuration, geometry, and arrangement where two or more parts, materials, or structural elements meet and connect. Its main goal is to safely transfer loads, manage stress distribution, and ensure structural durability or proper motion.
Design knowledge – It is the understanding and insights gained from studies and experiments into the act of designing, the design processes and principles, and the structural properties of designed objects. It encompasses the structuring of time and / or space to achieve specific purposes within given constraints and criteria. It is the structured understanding, rules, and practical ‘know-how’ used to plan, build, and evaluate artifacts or systems to solve human problems. It bridges abstract ideas and physical or digital realities by combining human empathy with technical constraints.
Design knowledge base – It is a structured digital library containing design rules, patterns, component libraries, and domain expertise. It helps teams store and share design choices, brand guidelines, and technical standards to keep products uniform and speed up development.
Design layout – It is an engineering drawing, either two-dimensional or three-dimensional, which shows the individual parts of a system in relationship to one another. An assembly drawing frequently serves the same purpose.
Design lifetime – It is also called design life. It is the planned period during which a system, structure, or component is expected to work safely and effectively under normal use and routine maintenance. It guides material selection, safety limits, and regulatory compliance before major overhauls are needed.
Design limit load – It is the maximum external force or stress which a structure is expected to encounter during its complete operational lifetime. Structures are to support this load level safely without experiencing any permanent deformation or yielding.
Design limit stress – It is the maximum safe internal mechanical stress a material or structure is allowed to experience under operational loads. It acts as a threshold boundary, derived from material yield or ultimate strength divided by a safety factor, to prevent structural failure, yielding, or cracking.
Design load – It is the maximum combined force, weight, or pressure which an engineer calculates which a structure, building, or machine is to support safely during its lifetime. It multiplies standard expected forces by extra safety factors to prevent breaking or falling apart.
Design location – It is the exact physical or digital spot chosen for a project, object, or node. It sets the rules for how a space, map coordinate, or software element fits into its real-world or virtual environment. It is the process of selecting optimal sites for nodes in a network to minimize total costs associated with location and access, while considering constraints such as the maximum number of areas a node can handle and ensuring each area connects to only one node.
Design manager – Design manager is a professional responsible for making design work a competency within an organization, which involves establishing formal structures for leveraging design, managing internal resources and external partners, and integrating design efforts into different organizational functions.
Design margin – It is the difference between a system’s actual capability and its specified minimum requirements. It acts as an intentional buffer of performance, strength, or capacity added to ensure the system safely survives extreme operating conditions, environmental changes, and unforeseen uncertainties. Understanding design margins ensures systems remain robust against things like component aging, manufacturing tolerances, and power / temperature fluctuations.
Design matrix – It contains data on the independent variables (also called explanatory variables), in a statistical model that is intended to explain observed data on a response variable (frequently called a dependent variable).
Design meeting – It is a collaborative session where a team plans, reviews, or refines creative work, product concepts, or project blueprints. Its goal is to align stakeholders, solve problems, and make decisions to move a project forward.
Design methods – These are procedures, techniques, aids, or tools for designing. They offer a number of different kinds of activities which a designer can use within an overall design process. Conventional procedures of design, such as drawing, can be regarded as design methods, but since the 1950s new procedures have been developed which are more normally grouped under the name of design methods. What design methods have in common is that they ‘are attempts to make public the hitherto private thinking of designers i.e., to externalize the design process’.
Design mode – It is an editing state in software, web development, and user interfaces where a user or developer builds, configures, and modifies structure and layout rather than running or executing the live application.
Design model – It is a digital, physical, or diagrammatic blue-print which translates system requirements or creative concepts into a structured plan. It guides implementation, simulates real-world function, and clarifies how components connect before final production.
DesignModeler – It is a dedicated software tool to create, edit, and clean up 3D and 2D geometric models before running computer simulations. It acts as the main pre-processing geometry engine inside the Ansys work-bench environment.
Design objectives – These are the specific, actionable goals and desired performance characteristics which guide the creation of a product, system, or process. They translate high-level user needs and organizational requirements into clear benchmarks, helping to measure success while balancing functionality, cost, and aesthetics. Having clear design objectives ensures that a project does not drift from its core purpose. They act as the main filter for decision-making.
Design of a forging practice – For an open-die forging, it involves the selection of certain parameters to be used, such as die dimensions and shapes, quantity of reduction, ingot shape, temperature gradient, ram velocity, and pass sequence.
Design of experiments – It is a methodology involving statistically designed experiments in which the character and sequence of individual experiments are planned in advance so that data are taken in a way which provides the most unbiased and precise results commensurate with the available time and money. The chief classes of statistically designed experiments are (i) blocking designs to remove the effect of background variables from the experimental error, (ii) factorial designs, in which all levels of each factor in an experiment are combined with all levels of every other factor, and (iii) response surface designs, which determine the empirical relation between the factors (independent variables) and the response (performance variable).
Design of experiment method – It refers to a set of techniques for determining sample point locations in a design space, aimed at maximizing information about the space with a minimal number of samples. It can be classified into classical methods, used for laboratory experiments with random errors, and modern methods, used for deterministic computer simulations.
Design of experiments technique – It is a structured, statistical technique used to identify relationships between multiple input factors and a process’s output. By varying several variables simultaneously, design of experiments (DOE) uncovers complex interactions that traditional ‘one-factor-at-a-time’ (OFAT) testing misses, allowing researchers to optimize processes while minimizing the number of experimental runs.
Design office – It is a workspace which provides services to different departments, including engineering, sales, service / maintenance, and manufacturing, by producing drawings, charts, and documentation necessary for product development, production, and after-sales support.
Design operating conditions – These conditions define the specific set of maximum, minimum, and normal parameters, such as pressure, temperature, and load, which equipment or structures are to safely handle during regular use and anticipated extreme scenarios.
Design opportunity – It is a clear gap, unmet user need, or technical inefficiency in the market which can be solved by creating or improving a system, product, or process. It marks the vital starting point where creative ideation meets practical technical constraints.
Design optimization – It consists of the process of searching for the best combination of design parameters. Design optimization suggests that for a given set of possible designs and design criteria there exists a single design which is the best or optimal.
Design optimization procedure – It is a systematic, mathematical method used to find the best possible design configuration from several alternatives by minimizing or maximizing a specific performance goal while respecting strict physical and operational limits.
Design option – It is an alternative way to solve a problem or meet a project requirement. Teams create multiple options early in a project to compare costs, safety, and performance before picking the best final choice.
Design-out maintenance – It is a set of activities which are used to eliminate the cause of maintenance, simplify maintenance tasks, or raise equipment performance from the maintenance point of view by redesigning those equipments and facilities which are vulnerable to frequent occurrence of failure and their long-term repair or replacement cost is very expensive.
Design paradigm – It is a fundamental mental model, framework, or style of solving problems. It guides how engineers conceptualize, structure, and implement systems. Rather than being a single blue-print, it represents the underlying rules, principles, and methods shared by a technical community.
Design parameters – It is a term used to describe the main variables of a design issue. It is sometimes called the design attributes or design characteristics. Design parameters define the object or process which is being designed and hence provide a means for changing the design for improving the performance.
Design performance measures – It consists of the performance measures which are functions of the design parameters and are used to quantify the effectiveness of a given design. Performance measures frequently are grouped into an objective function and the problem constraints.
Design perturbation – It is a small, controlled change applied to a system parameter, geometry, or load to evaluate how a design reacts without running full-scale simulations. It helps engineers optimize structures, test stability, and analyze sensitivities quickly.
Design phase – It is a core stage where project requirements are translated into detailed plans, blue-prints, and specifications. It bridges the gap between early high-level concepts and final physical production or construction.
Design plan – It is a formal roadmap document which outlines the goals, responsibilities, resources, and phases needed to develop a system, component, or product. It coordinates different teams, minimizes technical risks, and ensures project needs are met within budget and time limits.
Design position – It is a core technical role responsible for transforming abstract concepts and project needs into detailed, functional, and manufacturable physical or digital systems. These professionals bridge the gap between creative innovation and practical reality using modelling software, calculations, and prototyping.
Design practices – These are the iterative, systematic methods and observed habits engineers use to resolve design challenges, balancing functionality, constraints, and constraints.
Design precaution – It is a specific, built-in safety measure or constraint added early during the planning and design phase. Its goal is to eliminate, reduce, or control potential hazards, equipment failures, and operational risks over the entire life cycle of a product, structure, or system.
Design presentation – It is a structured communication event or visual artifact used to explain a technical concept, project proposal, or prototype to stakeholders, clients, or team members. It outlines how a proposed system, component, or process solves a specific problem within defined constraints.
Design pressure – It is the peak internal or external pressure a system, vessel, or piping component is explicitly built to withstand safely at a specific design temperature. It always equals or exceeds the maximum normal operating pressure, incorporating safety margins for surges or upset conditions.
Design principles – These are fundamental guidelines and rules used to develop, optimize, and evaluate functional products or systems. They ensure designs meet performance requirements, are safe, and satisfy client needs within physical and economic constraints. These principles act as a framework to manage complexity and prioritize safety, manufacturability, and efficiency.
Design problem – It is an open-ended challenge which does not have a unique answer, needing multiple potential solutions or designs which can vary in effectiveness based on critical requirements. It frequently involves complex and poorly formulated issues, necessitating creativity beyond traditional problem-solving methods.
Design procedure – It is a systematic, step-by-step method which engineers use to solve problems, create products, or build systems. It combines mathematics, science, and creative thinking. It is an ongoing cycle. Teams repeat steps to fix flaws and make the final design better.
Design process – It is a systematic, step-by-step analytical procedure used to develop and refine a product, considering aspects such as quality, materials, processes, assembly, maintenance, functionality, and usability. It encompasses the evolution of design and the learning derived from design failures.
Design process model – It is a structured approach to design which typically involves four key stages namely discover, define, develop, and deliver, incorporating both divergent and convergent thinking modes used by designers.
Design producibility – It defines how easily, economically, and reliably a product can be manufactured at scale. It involves aligning product design with specific manufacturing processes, capabilities, and constraints to minimize complexity, reduce tooling costs, and ensure consistent quality from the earliest development stages.
Design project – It is a collaborative effort by one or more individuals working over a specified period to achieve an agreed goal or outcome, needing efficient planning and management to complete it on time, to a standard, and within a budget.
Design provision – It is a specific rule, safety measure, or future capacity built into a plan or structure. It ensures compliance with codes, handles operational limits, or prepares systems for future expansion.
Design purpose – It refers to the objectives or goals which guide the creation of a design, encompassing the intentions behind the arrangement of elements in engineering projects. This concept is frequently detailed in a document known as the design basis or basis of design.
Design quality – It embeds robust standards, risk prevention, and testing frameworks early into the product creation phase, ensuring both physical goods and software systems meet safety, reliability, and user expectations prior to mass production or release. It is a combination of technical quality and desirability of a product, which influences customer satisfaction and their willingness to use the product. It encompasses aspects such as product longevity, surface quality, and customization to meet individual needs.
Design related issues – These refer to the different considerations in product development which influence the creation and functionality of products, including structural robustness, material selection, thermal management, and compliance with safety and environmental standards. These issues are important for ensuring product reliability and meeting manufacturing requirements.
Design requirement – It is a formal document which outlines the specific functions, performance targets, features, and constraints a product or system is required to satisfy to be successful. It translates broad user needs into testable, objective engineering criteria.
Design review – A design review is a milestone within a product development process whereby a esign is evaluated against its requirements in order to verify the outcomes of previous activities and identify issues before committing to, and if need be, to re-prioritize further work. The ultimate design review, if successful, hence triggers the product launch or product release. The conduct of design reviews is compulsory as part of design controls, when developing products in certain regulated contexts.
Design rules – These are a set of guidelines which are developed from experience and which tell the designer how to make decisions in typical situations. Frequently these rules suggest how to design to minimize cost of manufacture, e.g., to try to design the part so it can be machined on one machine tool only.
Design sensitivity – It is an analytical method for determining the importance of each design parameter to the performance of the design (output measure) and the critical ranges of those parameters.
Design, sample – Sample design is a structured approach to selecting observation sites and times which accurately represent the behaviour of interest, aiming to minimize bias and improve the generalizability of survey results to the larger population. It involves methods such as randomization and statistical weighting to improve the accuracy of behavioural estimates.
Design science – It is a systematic research paradigm focused on creating and evaluating artificial artifacts, such as products, systems, and methods, to solve practical problems and generate prescriptive knowledge about how things ‘ought to be’ rather than just how they are.
Design science research – It is a a problem-solving paradigm which creates and evaluates innovative artifacts, such as models, methods, constructs, and systems, to solve real-world practical problems and generate prescriptive design knowledge. It focuses on how things ‘ought to be’ to reach specific goals, rather than only explaining how things currently are.
Design selection – It is frequently called material or component selection. It is the systematic process of identifying and choosing the optimal materials, geometries, and manufacturing methods to fulfill specific functional, economic, and performance requirements of a product.
Design sensitivity analysis – It computes the partial derivatives of system performance measures, such as stress, weight, cost, or resonant frequency, with respect to design variables like dimensions or material properties to see how output changes when inputs shift.
Design service life – It is the planned time period which a structure, equipment, or component is meant to function safely and reliably under expected operating conditions, allowing for routine maintenance but avoiding major structural or system repairs.
Design solutions – These refer to the outcomes of the design process, which involve balancing different dynamic forces, such as economy, performance, simplicity, and inter-fit, within the context of the problem area. These solutions are required to adjust to the surrounding context while effectively addressing the defined problem. Design solution is the formal process of translating high-level requirements and logical models into a finalized, actionable plan or blueprint that solves a specific problem while balancing performance, cost, and safety constraints.
Design space – It is the multi-dimensional range of input variables, material attributes, or geometric boundaries which ensures a system, product, or process meets all quality and performance requirements. Operating safely inside this defined zone avoids failure and regulatory or structural changes.
Design specification – It is a precise, authoritative document which translates user needs into the technical requirements, constraints, and physical parameters a system or product is to satisfy. It outlines ‘how’ a solution is built rather than just what problem it solves.
Design spectrum – It is a smooth, standardized curve used by structural engineers to find the maximum expected acceleration, velocity, or displacement a building is going to experience during an earthquake. It serves as a safe upper-limit guideline defined by building codes.
Design stage – It is a distinct, structured phase where an idea transforms into a tested, buildable plan. It moves from basic problem definition to detailed manufacturing or construction blue-prints.
Design standards – These are agreed-upon descriptions of best solutions to repetitive design issues, arrived at by general consent of an appropriate broad-based technical group. While standards do not have the force of law, they frequently are incorporated into a design code.
Design strain – It refers to the strain imposed on a pipe-line because of the external factors, which is critical for evaluating whether the pipe-line can withstand the strain capacity without failure. It is an important component in the strain-based design methodology, particularly in conditions where strains gradually accumulate over time.
Design strength – It is the safe, reduced load-carrying capacity of a material or structural element. It is calculated by multiplying the nominal (ideal) strength by a resistance factor, or by dividing it by a safety factor, ensuring the component safely withstands expected forces.
Design stress – It is the maximum permissible stress which an engineer intentionally calculates and sets as a limit for a material or structure. It ensures structural safety by preventing material failure, yielding, or fracture under worst-case loading conditions. It is also known as allowable stress design.
Design structure matrix – It is a simple, compact and visual representation of a system or project in the form of a square matrix. It is used in systems engineering and project management to model the structure of complex systems or processes, in order to perform system analysis, project planning and organization design. It lists all constituent subsystems / activities and the corresponding information exchange, interactions, and dependancy patterns.
Design studio – It is a collaborative work-space or an interactive problem-solving method where multi-disciplinary teams rapidly brainstorm, prototype, and iterate technical solutions while balancing aesthetic form with manufacturing feasibility.
Design style – It refers to a structured, repeatable approach or methodology used to solve technical problems, make structural and functional choices, and organize the creation of systems, products, or software. It governs how requirements are translated into reliable, maintainable physical or digital implementations.
Design system – It is a single source of truth containing reusable UI (user interface) components, coded elements, design tokens, and clear usage rules. It bridges design and software development so teams can build scalable, accessible, and consistent digital products fast.
Design, tandem – Tandem design means arranging two or more identical or matching components, systems, or loads one behind the other (in series) to share work, boost power, or provide a safety back-up.
Design task – It is a clear statement which outlines the goals, rules, limits, and needs of a project. It guides the team on what to build, why to build it, and how to measure success before actual work starts.
Design team – It is a multi-functional group which contains not only the technical expertise to design the product but also expertise in manufacturing and marketing.
Design team member – Design team member is a technical professional responsible for conceptualizing, modelling, testing, and refining systems, products, or structures. These professionals bridge creative problem-solving and practical manufacturing, turning project requirements into safe, functional, and cost-effective production-ready plans.
Design technique – It is a specific, structured method or tool used to turn a functional problem into a working, tested physical or digital solution. It guides how engineers brainstorm, plan, calculate, and optimize systems safely and efficiently.
Design temperature – It is the design temperature of the piping system in which the valve is operating in. The valve is to be designed to this temperature.
Design tools – These are physical items, media, or computer programmes used to plan, create, and build creative work. They help turn ideas into clear visual forms.
Design ultimate load – It is the maximum calculated force or weight a structure, machine, or component is required to safely support before reaching the point of potential collapse or structural failure. It is found by multiplying the expected normal working load (service load) by a safety or load factor.
Design ultimate strength – It is the maximum stress or load a material or structural member can withstand before it breaks or collapses. In engineering design, it represents the peak point on a stress-strain curve used to calculate safety margins against total structural failure.
Design velocity – It refers to the selected speed of vapour flow in a system which influences the minimum tower diameter and operational flexibility, with considerations for efficiency, pressure drop, and expected vapour rates.
Design verification – It is a formal process used to confirm that a product’s design outputs meet its specified design inputs, ensuring it has been built right through testing, analysis, or inspection.
Design water-line -It is the specific horizontal plane at which a vessel is intended to float when loaded to its normal, pre-planned operational weight. It serves as the main baseline reference for hydrostatic calculations, stability criteria, and hull form evaluation.
Design wave – It is a specific, hypothetical wave chosen by engineers to test or build safe structures like ships, oil platforms, and sea walls. It uses past weather data and math to predict the largest, most severe wave an ocean structure can face over a span of several years.
Design working condition – It is the specific set of physical, environmental, and operational parameters (such as peak load, pressure, temperature, and speed) established as the base-line limit for which a system, machine, or structure is planned, calculated, and built to perform safely and reliably.
Design working life – It is the planned time period a structure or product is to perform safely and reliably under expected use, assuming regular upkeep but no major structural repairs. It acts as a target for material choice and durability.
Desiliconization – It is a refining process used in steelmaking to reduce the quantity of silicon dissolved in molten iron (hot metal). It typically lowers silicon levels to around 0.15 % or less before the metal enters the primary oxygen furnace. This step optimizes slag volume, prevents excessive lining wear, and helps subsequent dephosphorization.
Desiliconization of hot metal – It is the removal of silicon from the hot metal prior to the oxygen converter process. Silicon removal is beneficial to the converter to reduce the chemical attack on the basic refractory lining and to allow the use of only minimal amounts of slag-making fluxes, thereby maximizing process yield. These are several methods which are being used for desiliconization of hot metal including adding iron ores or sinter to hot metal during its flow in blast furnace runner.
Desilter – It is a centrifugal surface device, typically built with multiple small hydrocyclone cones, used to remove very fine solid particles, such as silt (ranging from 15 micro-meters to 45 micro-meters in size), from drilling fluids or industrial slurries.
Desirability – It refers to a method used to address multiple and frequently conflicting responses by associating each response with its own partial desirability function, with the optimum point identified as the one with the highest desirability function. A large area of desirability indicates a robust formulation or process. It is the quality of being worth having, wanted, or attractive. It means something has traits that make people want to choose or own it.
Desired joint angles – These refer to the calculated angles which a manipulator is to achieve in joint space to follow a specified trajectory in Cartesian coordinates, derived through inverse kinematics from the desired position, velocity, and acceleration in the desired trajectory.
Desired parameters – These refer to specific values or ranges for measurable factors, such as temperature and pressure, which machinery is to operate within to function effectively and meet particular requirements.
Desired pressure – It refers to the target or setpoint pressure value needed for a specific system, process, or mechanical setup to operate correctly. In engineering, fluid power, it is the exact level of force per unit area which a controller, regulator, or operator aims to achieve and maintain.
Desired radio frequency – It is the specific, target electro-magnetic wave frequency which a receiver, tuner, or communication system is set to catch, use, and process while blocking out unwanted noise or other signals.
Desired requirement – It is a non-mandatory feature or quality which stakeholders want. It adds value, but the project or product can still succeed without it. It contrasts with a mandatory requirement, which is an absolute rule that a system is required to meet. Desired requirements are the specific attributes or features which potential customers prioritize for a product, which can be rated based on their importance. These requirements are typically evaluated through customer surveys to guide design decisions.
Desired service life – It is the target time period which a material, structure, product, or asset is intentionally designed and planned to remain functional, safe, and useful under expected operational and environmental conditions.
Desired signal – It is the specific, useful piece of information or wave-form which a system intends to capture, transmit, or process. It stands in direct contrast to unwanted background noise, distortion, or interference signals which contaminate the transmission channel.
Desired spectrum – It is the specific range of frequencies, wavelengths, or energy levels targeted and needed for a particular technical, scientific, or signal-processing application. It defines the exact goal frequency or spectral shape needed to make a system work properly.
Desired state – It is the defined, intended configuration or operating condition that an administrator or system dictates. Rather than manually issuing step-by-step commands, engineers declare what the system is required to look like, allowing automated agents to continuously align the actual system with this base-line.
Desired system response – It is the exact, expected output or behaviour which a system is required to produce when given a specific input or command. It sets the goal or target performance standard for engineering, software, and control systems.
Desired target – It is a specific, planned result or endpoint which a person or group wants to reach. It combines a wish or a need (desired) with a clear, measurable goal (target”).
Desizing – It is the process of eliminating sizing, which is normally starch, from gray (also greige) goods before applying special finishes or bleaches (for yarn such as glass or cotton). It is also removing lubricant size following weaving of a cloth.
Desk study – It a preliminary research method which collects and analyzes existing secondary data rather than gathering new data first-hand. It is also known as desktop research or secondary research.
Desludging – It is the process of removing sediments by draining and cleaning a tank.
Desorption – It is a process in which an absorbed material is released from another material. Desorption is the reverse of absorption, adsorption, or both.
Desorption-adsorption reaction – It is a reversible surface process where molecules attach to a solid or liquid surface (adsorption) and later release back into the surrounding phase (desorption). This dynamic equilibrium controls how substances interact at material boundaries.
Desorption of a gas molecule – It is the physical or chemical process where gas molecules which are stuck to a solid or liquid surface are released back into the surrounding space. It is the exact opposite of adsorption.
Destination address – It refers to the 32-bit field in the IP (internet protocol) header which contains the receiver’s internet protocol (IP) address, indicating the intended end-point for data transmission.
Destination network – It refers to the final target subnet or network prefix where a data packet is meant to arrive. Routers use this address range to guide data across different systems.
Destination node – It is the final end-point in a network or graph where a data packet, message, or flow of information stops and is processed. It is the intended receiver opposite to the source node which originally sent the data.
Destination point – It is the final geographic location, address, or terminal where a person, vehicle, or shipped item is meant to arrive. In logistics and organizational contracts, it marks the end of a journey or the exact spot where ownership and liability of goods transfer from a seller to a buyer.
Destination register – It is a specific storage location inside a computer’s central processing unit (CPU) which holds the final result of a data processing or arithmetic operation.
Destruction – It refers to the irreversible failure or decomposition of materials and structural components under extreme load. It encompasses the physical process of pulling down a structure (demolition) or the quantitative analysis of stress-strain limits.
Destruction cost rate – It is very frequently known as the exergy destruction cost rate. It is the monetary value of the energy or work lost because of the irreversibilities (such as friction, heat leakage, or chemical inefficiency) in a thermodynamic system per unit of time.
Destructive distillation – It is a chemical process in which decomposition of unprocessed material is achieved by heating it to a high temperature. The term normally applies to the processing of organic material in the absence of air or in the presence of limited amounts of oxygen or other reagents, catalysts, or solvents, such as steam or phenols. It is an application of pyrolysis. The process breaks up or ‘cracks’ large molecules. Coke, coal gas, gaseous carbon, coal tar, ammonia liquor, and coal oil are examples of commercial products historically produced by the destructive distillation of coal. Destructive distillation of any particular inorganic feedstock produces only a small range of products as a rule, but destructive distillation of many organic materials commonly produces very many compounds, often hundreds, although not all products of any particular process are of commercial importance.
Destructive examination – It is an investigative and testing process where a material, component, or product is intentionally stressed, cut, deformed, or broken to its breaking point. This permanent damage reveals internal structural flaws, mechanical limits, and precise failure modes.
Destructive interference – It occurs when two overlapping waves meet in such a way that their crests and troughs cancel each other out. This results in a new wave with a smaller amplitude, or complete silence / darkness if the original waves are identical in size but opposite in alignment.
Destructive methods – These methods are also known as relaxation methods. These methods break, damage, or destroy a material or sample on purpose, to find the breaking point, strength, and limits of a product. Destructive methods include a variety of techniques for measuring residual stresses in various engineering components. Although these methods, compared with their nondestructive counterparts, may seem less attractive due to the permanent damage they cause to the part, it is to be noted that because of their versatility and reliability, these methods have found vast applications in residual measurement studies.
Destructive technique – It is a testing or analytical method where a sample is intentionally damaged, deformed, or broken to measure its physical limits, mechanical strength, and behaviour under stress. Since the item is ruined during the process, the technique is used it on sample batches rather than final products.
Destructive testing – It is a process which tests a material or product by damaging or breaking it. Key methods include tensile testing, compression testing, and impact testing. It is used to find the absolute limits of strength and safety.
Desublimation – It is also called deposition. It is a phase change where a gas turns directly into a solid without becoming a liquid first. It is the exact opposite of sublimation.
Desulphurization – It is a chemical process of removing sulphur impurities from molten metals, mainly iron and steel. It is a critical refining step performed in the furnace or ladle prior to casting to improve the metal’s mechanical properties, weldability, and corrosion resistance.
Desulphurization rate – It is the percentage or speed at which sulphur or sulphur compounds are removed from a substance, such as fuel, gas, or industrial exhaust. It measures how well a system cleans sulphur out.
Desulphurization reaction – It is a chemical process which removes sulphur or sulphur compounds from materials like petroleum, natural gas, or industrial exhaust. It converts harmful sulphur into safe compounds like hydrogen sulphide or solid gypsum to stop air pollution and acid rain.
Desulphurizer – It is also called desulphurizing agent. It is a chemical compound or material used to extract and bind with sulphur impurities in molten metals like iron and steel. This purification step is important since excess sulphur causes metals to become brittle or prone to cracking (hot shortness) during shaping and rolling.
Desulphurizing – It is the removal of sulphur from molten metal by reaction with a suitable slag or by the addition of suitable compounds.
Desynchronization attack – It happens when two or more connected systems lose agreement on message boundaries, sequence counters, or timing. This mismatch causes them to misinterpret where one data packet ends and the next begins, leading to security bypasses, repeated transmissions, or system crashes.
Detachable chain link – It is a chain link designed for easy detachment during maintenance or replacement, needing periodic inspections for wear and secure attachment.
Detached eddy simulation – It is a hybrid computational fluid dynamics (CFD) method which blends Reynolds-averaged Navier-Stokes (RANS) and large eddy simulation (LES) approaches. It uses RANS (Reynolds-averaged Navier-Stokes) near solid walls to save computer power and LES (large eddy simulation) in separated flow regions to resolve large turbulent eddies.
Detail coefficient – It is a numerical value generated during a discrete wavelet transform which captures high-frequency, rapid changes, or minute details in a signal or image. It contrasts with an approximation coefficient, which represents the low-frequency, macro characteristics of the data.
Detail design – It is the final phase of design in which all information on materials, manufacturing processes, dimensions, and tolerances are supplied. The output of this design phase is a complete set of drawings and product specifications. It is also known as parametric design.
Detail design phase – It is the project stage where an approved concept or basic design is transformed into precise, execution-ready specifications, complete drawings, and physical or digital models needed for manufacturing, construction, or coding. It bridges high-level creative intent and final production.
Detail drawing – Detail drawing is the engineering drawing of any kind of geometric structure which is to be constructed. The drawing is more detailed and pay attention to the intricate designs and details of any construction project. Detail drawing is an engineering drawing presenting single item (object / equipment component / work-piece etc.). The drawing is meant for enabling a person in a workshop to produce (by machining / casting / forging / fabricating etc.) the desired item. Such details as dimensional tolerances, surface finish, special treatments, material to be used for the component etc. are specified. The number of views to be presented depends on the complexity of the item. In several situations, sectional views are included to show hidden details which cannot conveniently and explicitly appear in any external view.
Detailed assembly drawing – It is normally made for simple equipments, comprising of a relatively smaller number of simple parts. All the dimensions and information necessary for the construction of such parts and for the assembly of the parts are given directly on the assembly drawing. Separate views of specific parts in enlargements, showing the fitting of parts together, can also be drawn in addition to the regular assembly drawing.
Detailed assessment – It is a rigorous, quantitative evaluation used to verify design feasibility, check initial assumptions, and determine the exact structural or functional limits of a system, structure, or product. It acts as the important bridge between early planning and full-scale manufacturing or construction
Detailed design stage – It is the project phase where an approved concept or schematic design is expanded into fully coordinated, dimensionally accurate, and specific plans. It defines exact materials, components, dimensions, and system layouts, providing the necessary information for statutory approvals and final production or tender packages.
Detailed emergency planning zone – It is the area around a facility for which the regulations need the local authority to prepare a detailed off-site emergency plan with the purpose of restricting, as far as reasonably practicable, exposure to the public in the event of a radiation emergency.
Detailed engineering – It takes place during the actual project execution phase. It consists of producing drawings and documents which are necessary for (i) manufacturing of the plant and equipment, (ii) carrying out civil foundations, (iii) fabrication of building and technological structures, (iv) erection of structures as well as plant and equipment, (v) laying of cables and making of electrical and instrument connections, and (vi) laying of pipes and piping connections etc. During the detailed engineering, the information from the suppliers is integrated with other information of the project. Also, the responsibility of carrying out the detailed engineering is split between the suppliers and the project engineering personnel including the project consultants.
Detailed evaluation – It is an in-depth, rigorous, and systematic process of assessing the value, quality, compliance, or performance of a subject against pre-defined criteria. Unlike a quick preliminary screen or basic overview, it breaks down data completely to form evidence-based conclusions or final recommendations.
Detailed exergy analysis – It is an in-depth engineering method based on the second law of thermodynamics to measure the true quality, location, and magnitude of energy waste and losses in a system. It breaks down inefficiencies past standard energy accounting by tracking work potential and irreversibilities component by component.
Detailed feasibility report – It aims to provide an independent assessment which examines all aspects of a proposed project, including technical, economic, financial, legal, and environmental considerations. This information then helps decision-makers determine whether or not to proceed with the project. Detailed feasibility report evaluates a set of proposed project paths or solutions to determine if they are viable.
Detailed functional specification – It is a formal document which describes what a system, product, or software application is required to do. It acts as a blue-print for developers and stakeholders, focusing on user interactions, system inputs and outputs, work-flows, and organizational rules without detailing the internal code or technical architecture.
Detailed model – It is a precise, highly specific representation of a system, product, or process which includes extensive data, exact dimensions, and explicit operational rules. It moves beyond basic conceptual frameworks to serve as an authoritative source for manufacturing, analysis, or simulation.
Detailed process simulation – It is a computer model which uses mathematics rules, real data, and physical laws to mimic a real-world system. It lets users test changes, find weak spots, and see how the system works over time before making changes in real life.
Detailed project report – It is a blueprint of a project with an extensive and elaborative outline of a project, which includes essential information such as the resources and tasks to be carried out in order to make the project turn a success. Detailed project report is the document which gives a 360-degree view of any project. It is an important document.
Detailed view – It is an enlarged, scaled-up types of views in engineering drawings. It indicates precise dimensions or tolerances which are too small to be read clearly on the main scale. Detailed views are drawn at a larger scale than the main drawing to provide clear legibility. For example, if the main drawing is at a 1:5 scale, the detailed view can be scaled at 2:1 or 5:1. The section of the main drawing being enlarged is encircled or framed by a boundary (frequently a circle, ellipse, or spline) and labeled with an identifying letter (e.g., Detail A, Detail B).
Detail image – It is a close-up visual which highlights small parts, textures, or specific features of an object, product, or artwork which are not clearly visible in a standard full view.
Detail preparation – It is the thorough, specific actions taken to make a person, place, or material completely ready for a task. It involves fine-scale planning, organizing parts, and setting exact conditions so that the next main step works well.
Detectability – It is the quality or state of being able to be discovered, noticed, or measured. It shows how easy or hard it is to find a signal, a hidden object, a fault, or an event using the senses or tools.
Detectable concentration – It is limit of detection (LOD) or minimum detectable concentration (MDC). It is the lowest quantity or concentration of a substance which can be measured and told apart from a blank sample with a set level of statistical confidence.
Detectable limit – It refers to the minimum detectable limit (MDL) or limit of detection (LOD) in analytical techniques, which indicates the lowest concentration of a substance which can be reliably identified in a sample.
Detected flaw – It is an identified imperfection, error, or physical discontinuity in a product, structure, software code, or material which has been found through inspection, testing, or analysis.
Detected neutron – It is a neutral sub-atomic particle whose presence and energy are successfully identified and measured by an indirect conversion process in a specialized sensor. Since neutrons carry no electrical charge, they cannot be seen directly by standard charge-based ionizers. Instead, they are to first trigger a nuclear reaction which releases charged secondary particles.
Detected particle – It is a subatomic or ionizing unit of matter or radiation whose presence, energy, momentum, or charge has been registered and measured through its physical interaction with a specialized scientific instrument, known as a particle detector.
Detected segment – It is the specific criteria, boundaries, or structural parameters used by an algorithm to identify, isolate, and extract a distinct portion of data, video, audio, or image space from a larger continuous stream.
Detecting capability – It refers to the ability of a sensor or system to identify and measure specific conditions, such as the early identification of water infiltration in adhesive bond-lines, which is necessary for maintaining the health of bonded structures.
Detecting flaws – It refers to the process of identifying imperfections, such as cracks or inclusions, within a component, which can be accomplished through different non-destructive evaluation methods, including ultrasonic testing. This process is important for assessing the integrity of structures and determining whether a defect can lead to component failure.
Detection – It normally refers to the use of sensors, logic, or algorithms to discover, identify, or measure the presence of a specific condition, object, or anomaly. The definition shifts depending on the field, but it universally focuses on extracting meaningful signals from background noise.
Detection algorithm – It is a computational process or mathematical set of rules designed to identify, locate, or isolate specific targets, patterns, signals, or anomalies within a dataset. At its core, the algorithm operates by analyzing an input field, extracting relevant features, and comparing those values against a pre-determined threshold or base-line to decide whether a target is present.
Detection and attribution – These consist of a scientific process that involves identifying statistically significant changes in the climate system, and then determining the extent to which those changes can be attributed to human activities or natural causes. Detection refers to demonstrating that a climate variable or system has changed in a statistically meaningful way. Attribution involves evaluating the relative contributions of different factors, including human-induced (anthropogenic) and natural forcings, to the observed changes and assigning a level of confidence to the causal models used.
Detention basin – It is an excavated or natural depression designed to temporarily store stormwater runoff during heavy rain and release it slowly at a controlled rate to prevent downstream flooding and erosion. Also called a dry pond, it remains completely dry between storm events.
Detection bias – It is a systematic error which occurs when outcomes are measured, collected, or verified differently between comparison groups in a study. Also known as ascertainment or observer bias, it frequently happens when researchers or assessors know which participants received a specific treatment, leading them to scrutinize one group more than another.
Detection capability – It is the lowest concentration, signal, or object size which a system, sensor, or analytical method can reliably identify with a defined statistical certainty. It accounts for potential false-negative errors and measurement variations.
Detection device – It is an instrument or sensor used to identify, track, or measure specific physical objects, substances, environmental changes, or security threats. It converts physical inputs into signals which trigger alarms, display data, or alert users.
Detection format – It refers to the different measurement strategies developed in SPR (surface plasmon resonance) assays to generate a measurable sensor response from target-probe binding events, including direct detection, sandwich, and competitive assays.
Detection limit – It is the level at which radioactivity can be detected above background levels. It is the minimum value of the characteristic being measured which can be detected at a known confidence level.
Detection probability – It is also called probability of detection (POD). It is the likelihood that a target, signal, or item of interest is successfully found or identified given that it is actually present. It is expressed as a value between 0 and 1 (or 0 % to 100 %) and varies across different fields.
Detection scheme – It is a structured plan, method, or system used to identify specific events, faults, signals, or threats. It relies on pre-defined rules, algorithms, or models to analyze data streams, separate normal behaviour from anomalies, and trigger an appropriate response or alert.
Detection sensitivity – It is the smallest quantity of a target signal, substance, or physical property which a measuring instrument or test can reliably register. It is normally calculated as the change in the detector’s output signal divided by the change in the input quantity being measured.
Detection space – It is the overall multi-dimensional or physical range within which a sensor, system, or algorithm can successfully perceive, locate, or identify a specific target, signal, or object. It is also the process of identifying available spectrum channels, particularly in TV (television) white spaces, using methods such as spectrum sensing and geolocation databases. It involves different systems and protocols designed for both outdoor and indoor environments to assess channel availability effectively.
Detection task – It is the process of identifying and locating objects within an image, which includes both classification and localization components. It is frequently applied in different scenarios, including those with poor visibility, such as underwater environments. It is a core process in computer vision and machine learning where a system identifies the presence of specific items in data and finds their exact physical location. It merges two distinct steps namely classification (naming what the item is) and localization (marking where it sits).
Detection theory – It is also called signal detection theory. It is a statistical and psychological framework used to measure how well a system or person can distinguish meaningful patterns (signals) from random back-ground interference (noise) when making decisions under uncertain conditions.
Detector arm – It is a movable mechanical or structural boom which holds a radiation or particle detector. It is normally used in scientific instruments like X-ray or neutron reflectometers to record outgoing beam intensity at precise angles.
Detector array– It is an organized group of individual sensing elements arranged in a line (1D) or a grid / matrix (2D). Each tiny element captures light, radiation, or particles and turns them into electrical signals at the same time to form detailed images or spectral data.
Detector circuit – It is an electronic arrangement designed to extract specific information, measure peak values, or identify physical and electrical changes (such as amplitude, frequency, or threshold limits) from an input signal.
Detector count – It refers to the discrete number of individual physical events, such as X-ray photons, gamma-ray particles, or light quanta, registered by a sensor or measuring instrument over a set time period.
Detent – It is a spring-return device which maintains the position of the spool of a directional control valve in position.
Detergency and dispersant property – With the exception of detergency and dispersant property in the combustion chamber, deposits in the lubricating oil are controlled by its detergent power. The role of the detergent additives is to reduce the quantity of deposits formed and their removal easy. The detergent property imparted to the lubricating oils by additives seems to perform differently depending upon whether deposits result from high or low temperatures. Low temperature deposits are mainly come from the fuel combustion and the detergency function of the lubricating oil is to keep them in suspension or in solution in the lubricating oil. However, high temperature deposits are mainly related to the oxidized fraction of the oil. The role of detergency here is not only to maintain these products in suspension, but also to stop the development of those chain reactions which promote the formation of varnishes and lacquers. The physical and functional properties of the lubricating oils depend on the properties of the carbon atoms in the various ring structures and aliphatic side chain.
Detergent – It is a surface-active agent which possesses the ability to clean soiled surfaces. Types of Detergents are anionic, cationic, and nonionic.
Detergent additive – In lubrication technology, it is a surface-active additive which helps to keep solid particles suspended in an oil.
Detergent oil – It is a heavy-duty oil containing a detergent additive. Detergent oils are used mainly in combustion engines.
Detergent solution – It is a liquid mixture of water and synthetic soap-like compounds called surfactants. It lowers water surface tension to lift, break down, and suspend oil, grease, and dirt from surfaces so they can be washed away easily.
Deterioration conditions – These refer to the factors affecting the decline in structural performance over time, including the state of the tunnel structure, material properties, repair history, and environmental influences. These conditions are necessary for accurately modelling deterioration and predicting residual life in engineering applications.
Deterioration mechanism – it is the specific physical, chemical, or biological process which causes a material, structure, or system to lose its quality, strength, or function over time. Identifying these processes helps engineers and scientists predict service life and prevent failures.
Deterioration model – It is a mathematical or statistical framework used to predict how physical assets, structures, or systems degrade and lose performance over time. These models help managers forecast failures, optimize maintenance schedules, and extend asset life-spans.
Deterioration state – It refers to the condition of machines or assets at a specific time, represented by different levels of degradation, which can be classified into discrete stages based on pre-defined thresholds. This state information is important for the reinforcement learning agent to make informed maintenance decisions.
Determinant criterion – It is a rule or test used to make a decision or find a value. In mathematics and engineering, it normally means using a matrix determinant to test for matrix inversion, system solutions, or code performance in wireless signals.
Determine displacements – It refers to the measurement of the changes in position of a mechanical system during high strain rate nano-indentation testing, which is necessary for analyzing depth, strain rate, and dynamic contributions of the instrument. This measurement can be achieved using various sensors, including capacitance gauges, optical / laser interferometers, and piezoelectric transducers.
Determination – It is the ascertainment of the quantity or concentration of a specific substance in a sample.
Determining bond – It refers to the process of identifying the type of chemical bond formed between atoms in a material, which can include covalent, ionic, or metallic bonds, and is important for understanding the material’s chemical, physical, and mechanical properties.
Deterministic algorithm – It is a computational procedure which, given a specific initial input, always produces the exact same output while progressing through the identical sequence of internal machine states every time it runs. These algorithms eliminate all chance, randomness, or environmental variability, ensuring that system behaviours are entirely predictable and reproducible.
Deterministic case – It describes a system, model, or scenario where no random variables or probabilities exist, meaning identical starting conditions and inputs always produce the exact same outcome.
Deterministic channel – It is a communication channel where each input choice leads to a single, specific output with absolute certainty. Its transition matrix has only one non-zero probability element (equal to 1) in each row, meaning the conditional entropy H(Y|X) = 0.
Deterministic description – It is a precise, fixed account of a system, model, or process where the output is completely determined by the initial conditions and rules, with no role for chance or randomness. Repeating the same process with identical inputs always yields the exact same result.
Deterministic design – It is a design method which utilizes published values for minimum strengths and performance properties of materials, along with observed and hypothetical load scenarios, to specify types and sizes of structural materials needed to safely sustain those loads.
Deterministic dynamics – It refers to the behaviour of a system where the evolution of particle motions in a sheared suspension is influenced by purely deterministic forces, such as viscous hydrodynamic interactions, leading to chaotic diffusion despite the absence of random thermal fluctuations or turbulent effects. This process is characterized by sensitivity to initial conditions and a loss of memory in phase space, as evidenced by positive Lyapunov exponents in simulations.
Deterministic dynamic system – It changes over time in a completely predictable way. Given the same starting point and rules, it always produces the exact same future states and results with no random chance or luck involved.
Deterministic model – It is a system or formula that always produces the exact same output when given the same input. It contains no randomness, chance, or probability. Every future state or result is fully decided by the starting conditions and fixed rules.
Deterministic signal – It is a physical or mathematical quantity whose future and past values can be predicted precisely without any uncertainty. Since every data point is exactly governed by a known mathematical formula or rule, these signals do not contain new, unpredictable information.
Deterministic signal component – It is a predictable, exact part of a signal which follows a known mathematical formula or rule. It has no random uncertainty, meaning one can find its exact value at any time.
Deterministic solution – It is a method or outcome which always produces the exact same result from the same input data, with no random chance or probability involved.
Deterministic transformation – It is a systematic, rule-based process where specific inputs consistently yield the exact same output. It relies on fixed mathematical formulas, logic structures, or strict metadata rules. It contrasts sharply with stochastic or probabilistic methods, like unconstrained AI (artificial intelligence) by completely eliminating randomness, noise, or variation.
Detinning – It is the slow corrosion of the tin coating of a can.
Detonation – It is a type of combustion involving a supersonic exothermic front accelerating through a medium that eventually drives a shock front propagating directly in front of it. Detonations propagate supersonically through shock waves with speeds around I kilometer per second and differ from deflagrations which have subsonic flame speeds about 1 metre per second. Detonation can form from an explosion of fuel-oxidizer mixture. Compared with deflagration, detonation does not need to have an external oxidizer.
Detonation flame spraying – It is a thermal spraying process variation in which the controlled explosion of a mixture of fuel gas, oxygen, and powdered coating material is utilized to melt and propel the material to the work-piece.
Detonation gun process – It is also called D-gun process. It is an advanced thermal spray coating method. It utilizes the energy from controlled explosions of fuel and oxygen to heat and accelerate powder feedstock materials. These supersonic particles collide with a substrate to form dense, high-performance protective coatings.
Detonation phenomena – It refers to the supersonic combustion events where a high-intensity shock wave is coupled directly with a fast chemical reaction zone. The shock wave abruptly compresses and heats the material, releasing energy that continuously sustains the supersonic propagation wave at speeds typically ranging from 1,000 meters per second to 3,500 meters per second.
Detonation process – It is a strongly coupled phenomenon involving a leading shock wave and rapid chemical reactions, characterized by supersonic combustion and extremely high pressures and temperatures, resulting in the most complete energy release in material combustion. It encompasses distinct regions, including a shock wave, an induction zone for radical buildup, and a reaction zone which drives exothermic reactions.
Detonation wave – It is a supersonic combustion wave consisting of a leading shock front coupled directly to a trailing chemical reaction zone. The shock compresses and heats the material, instantly releasing energy which sustains the supersonic shock wave’s forward motion.
Detrimental effect – It is a negative consequence which causes harm, damage, or injury to someone or something. When an action, condition, or choice has a detrimental effect, it weakens or worsens the state of health, well-being, or success of the object or person affected.
Detritus – These are the particles which become detached in a wear process.
Detroit cup test – It is a specialized cupping method specifically used to evaluate the flow, deformation, and compactibility properties of foundry sands. It measures the depth of a cup formed in sand by a steel ball plunger, providing crucial metrics on sand workability for metal casting.
Deuterium – It is also known as heavy hydrogen. It is a stable isotope of hydrogen. While a standard hydrogen atom (protium) has only a single proton, a deuterium nucleus contains one proton and one neutron. Its atomic symbol is ‘2H’ or ‘D’.
Deuterium oxide – The chemical formula for deuterium oxide is D2O. It is normally known as heavy water. It is chemically identical to normal water (H2O) but is around 11 % denser since its hydrogen atoms are replaced by deuterium, a heavier, stable isotope of hydrogen containing one proton and one neutron.
Deuteron – It is the nucleus of the atom of heavy hydrogen, deuterium. The deuteron is composed of a proton and a neutron. It is the simplest multi-nucleon nucleus. Deuterons are used as projectiles in several nuclear bombardment experiments.
Deutsch–Jozsa algorithm – It is a foundational quantum algorithm which determines whether a given black-box Boolean function is constant (always outputs 0 or always outputs 1) or balanced (outputs 0 for half the inputs and 1 for the other half). It achieves an exponential speedup by solving this problem with only a single oracle query.
Developed blank – It is a sheet metal blank which yields a finished part without trimming or with the least quantity of trimming.
Developed country – It is a sovereign state with a high quality of life, a mature and advanced economy, and a sophisticated technological infrastructure compared to less industrialized nations. Key evaluation metrics include high gross domestic product (GDP), high per capita income, and strong scores in human welfare.
Developed data-base – It refers to a fully built, tested, and operational data system. It moves past the initial planning and blue-print stages into an active environment where users and software applications can safely store, update, query, and manage structured information.
Developer – Developer is a professional responsible for the end-to-end delivery of applications. Developers interpret requirements, design, code, test, and deploy features to solve user and operational problems.
Developed, expression – An ‘expression developed’ refers to a specific mathematical formulation or correlation created to estimate parameters in equations of state, such as the Soave-like expression for the attractive parameter ‘a(T)’ used in thermodynamic modelling.
Development – It is the systematic process of translating a concept, idea, or scientific discovery into a functional, validated, and ready-to-manufacture product or system. It bridges the gap between initial research and final production by testing prototypes, optimizing performance, and resolving practical limitations. In mining, development is the underground work carried out for the purpose of opening up a mineral deposit. It includes shaft sinking, cross-cutting, drifting and raising.
Development assurance – It is a planned, systematic set of actions and processes used to build confidence that a system, software, or hardware item satisfies safety and certification requirements by minimizing development errors. It focuses on rigorous planning, traceability, and verification rather than physical stress testing.
Development assurance level – It is frequently called design assurance level. It is a classification scale used in safety-critical engineering to measure the strictness of the development and testing process based on how badly a system or software failure can hurt the equipment or people operating the equipment.
Development board – it is a printed circuit board containing a micro-controller or micro-processor along with the supporting hardware, like power regulators, USB (universal serial bus) ports, and input-output pins, needed to easily write code, test electronic circuits, and prototype smart devices without building a system from scratch.
Development drilling – It consists of drilling to establish accurate estimates of mineral reserves.
Development error – it is a human mistake, oversight, or incorrect decision made during the planning, design, or coding phase of building a product or software. It represents a discrepancy between the intended specifications and the actual implementation before final deployment.
Development kit – It is a collection of software or hardware tools for aiding computer programmers in developing new software. The term frequently refers specifically to a software development kit (SDK), which is a collection of software development tools in one installable package.
Development phase – It is the core stage in a project or product life-cycle where plans, blue-prints, and designs are actively transformed into a functional, working product. In software, engineering, and organizational projects, it sits between the design phase and the testing phase.
Development plan – It is a structured action guide used in planning, employee growth, or organizational projects to reach specific future goals. It outlines clear objectives, necessary steps, and timelines over a set period.
Development project – It is a temporary, structured undertaking designed to create a specific product, service, or systemic change. It transforms a conceptual idea into a practical reality within an established timeline, budget, and resource limit.
Development standard – It is an official rule or set of guidelines which controls how products, software, or physical land are built and managed. It sets clear baselines for quality, safety, and best practices. Development standards are the rules and processes established by an authority or through general consent, aimed at guiding the creation and quality control of products and processes. They serve as benchmarks for safety, efficiency, and best practices within several domains, including engineering.
Development tool – It is a software programme or hardware utility used by engineers to design, build, test, analyze, and maintain systems or code. These instruments automate repetitive tasks, ensure product quality, and simplify complex work-flows across the engineering life cycle.
Development trend – It is the directional shift in how products, systems, or software are designed, built, and maintained over time, driven by emerging technologies, market demands, and sustainability goals. It highlights the movement away from older methods toward more efficient, intelligent, and scalable practices.
Deviation – A deviation is a departure from the specified standards or from an established process. Deviations can be intentional or unintentional, and they can occur at any stage of the production process. In statistical process control, it is difference between desired and actual values. It is used for difference between individual values and their mean.
Deviation process – It is a formal system used to manage any event, parameter, or result that departs from approved standard procedures, designs, or specifications. It ensures that unexpected changes or errors are tracked, assessed for risk, and resolved safely.
Deviation score – It is the difference between a variable’s value and the mean of the variable.
Deviation (X-ray) – It is the angle between the diffracted beam and the transmitted incident beam. It is equal to twice the Bragg angle theta.
Deviatoric invariant – It is a scalar value calculated from the deviatoric stress tensor which does not change when a person rotates the coordinate system. It measures the portion of stress responsible for shearing and changing a material’s shape rather than its volume.
Deviatoric plane – It also called the pi-plane or deviatoric stress plane. It is a flat geometric surface in principal stress space which is perpendicular to the hydrostatic axis (sigma1 = sigma2 = sigma3), representing purely shape-changing (shear / distortional) stress states without volumetric compression or tension
Deviatoric stress – It is the non-hydrostatic component of an applied stress that changes a metal’s shape (distortion) without altering its volume. It is primarily responsible for yielding, plastic deformation, and shearing in metals.
Deviatoric stress tensor – It is the component of the total stress tensor which remains after subtracting the hydrostatic (mean) stress. It is the part of the stress state responsible entirely for shape changes (distortion or shearing) and plastic deformation, without altering the material’s volume.
Device – It refers to an object or tool designed for a specific purpose. It is a broad term encompassing different forms of mechanical, electrical, or electronic tools and systems, used for tasks like computing, communication, handling, inspection, measurement, or automation.
Device behaviour – it specifies how a hardware or software component responds to inputs, transitions between states, and processes signals under defined operating conditions. It bridges physical characteristics and system logic to predict performance without always detailing internal physical structures.
Device driver – It is a specialized software component which acts as a translator and bridge between an operating system (or firmware) and a physical hardware peripheral. It converts high-level generic system calls into precise, low-level hardware commands.
Device evaluation – It is a systematic process used to test, appraise, and verify a device’s safety, performance, usability, and technical compliance against established standards before procurement, deployment, or market release.
Device manufacturer – It is the entity responsible for the physical design, prototyping, regulatory validation, and commercial production of physical equipment, hardware, or instruments. This term frequently centres on specialized sectors like technology, computing, or original equipment manufacturing (OEM).
Device programmer – It is a hardware tool used to load executable code, firmware, or data into the non-volatile memory of programmable integrated circuits like microcontrollers, flash chips, and FPGAs (field-programmable gate arrays). It acts as a bridge between a computer and physical hardware components.
Device scaling – It is the process of reducing the physical dimensions of electronic or micro-mechanical components, such as transistors and integrated circuits, while adjusting operating voltages and material properties to increase speed, raise component density, and improve power efficiency.
Device structure – It is the process of planning the physical layout, internal layers, and material framework of a technical tool, semi-conductor chip, or mechanical system so it safely performs its needed function. It connects high-level design goals with the actual physical parts.
Device surface – It is the digital and physical specification of a product’s outer boundaries. It defines CAD (computer-aided design) geometry, aesthetic quality tiers, and micro-textures to balance visual appeal, human touch, and manufacturing limits.
Device threshold voltage – It is the minimum gate-source voltage needed to create a conducting path between the source and drain of a transistor, with its value being adjustable through changes in substrate and channel dopant concentrations to optimize performance while managing leakage currents.
Device-to-device communication – It is the direct exchange of information between two or more devices without the need for an intermediary application server or connection point. This communication can occur over different protocols, such as Bluetooth, Zigbee, or Z-Wave, enabling devices to connect and interact with one another autonomously.
Device wafer – It is a thin, circular slice of semi-conductor material, very frequently single-crystal silicon, used as the foundational substrate for manufacturing micro-electronic integrated circuits (ICs), micro-electro-mechanical systems (MEMS), and solid-state devices. In semi-conductor engineering, it defines the active working area where electronic components like transistors are built.
Devitrification – It is the crystallization of an amorphous substance. In porcelain enamel, it is a surface defect caused by crystallization of the enamel because of the overfiring or contamination, resulting in the loss of the glassy, vitreous appearance of the surface.
Devolatilization – It is a mass-transfer process used to remove trapped volatile impurities, such as unreacted monomers, solvents, water, or gases, from a solid or viscous liquid, typically through heat and reduced pressure.
Devolatilization behaviour – It refers to how a solid or liquid material (such as coal, biomass, or polymer melts) releases gaseous components and volatile matter when heated. It dictates mass loss rates, product yields, and structural changes during thermal conversion or processing.
Devolatilization process – It is the release of gaseous fuel components from solid fuel when heated, which considerably influences flame ignition, stability, and the remaining char’s combustion properties. This process is affected by the fuel’s composition, heating rate, and temperature, resulting in varying volatile yields. It is a mass-transfer and thermal decomposition process used to remove volatile substances, such as unreacted monomers, solvents, water, or gases, from a solid material or polymer melt.
DeVries test – It is a standardized metallurgical evaluation used to measure the relative hardness of deep-hardening steels. It is mainly a quality control metric to ensure that specific steel grades have been heat-treated correctly and possess the necessary hardness profile to withstand heavy wear and impact.
Dewar – Itis a highly specialized, double-walled container used to store and transport extremely cold cryogenic liquids (such as liquid nitrogen or helium). It functions like a heavy-duty, industrial-grade thermos to prevent heat transfer and minimize fluid evaporation.
Dewar flask – It is a vessel having double walls, the space between being evacuated to prevent the transfer of heat and the surfaces facing the vacuum being heat reflective. It is used to hold liquid gases and to study low-temperature phenomena.
Dewatered sludge – It is a semi-solid, dense material produced by removing most of the water from liquid waste-water sludge. It typically contains 15 % to 45 % dry solids by weight. This mechanical reduction cuts waste volume and lowers handling costs before final disposal or treatment.
Dewatering process – It is the removal of water or moisture from soil, rock, or industrial waste streams (like sewage sludge). It creates dry, stable working environments for excavation or shrinks waste volume to ease material handling and lower transport costs.
Dewaxing – In casting, it is the process of removing the expendable wax pattern from an investment mould or shell mould. It is normally carried out by melting out because of the application of heat or by dissolving the wax with an appropriate solvent.
Dew point – It is the temperature and pressure at which a gas begins to condense to a liquid. Dew point is the temperature the air needs to be cooled to (at constant pressure) in order to produce a relative humidity of 100 %. This temperature depends on the pressure and water content of the air. When the air is cooled below the dew point, its moisture capacity is reduced and airborne water vapour condenses to form liquid water known as dew. When this occurs through the air’s contact with a colder surface, dew will form on that surface. The dew point is affected by the air’s humidity. The more moisture the air contains, the higher its dew point.
Dew point analyzer – It is an atmosphere monitoring device which measures the partial pressure of water vapour in an atmosphere.
Dextrin -It is a water-soluble carbohydrate derived from starch (through heat or acid). In the foundry industry, it acts as a premium sand core and mould binder. It provides the necessary bonding strength and permeability to hold sand shapes together before molten metal is poured.
Dezincification – It is a type of corrosion in which zinc is selectively leached from zinc-containing alloys leaving a relatively weak layer of copper and copper oxide. It is normally found in copper-zinc alloys containing less than 85 % copper after extended service in water containing dissolved oxygen.
Dezincification resistant brass – It is a duplex brass which has an arsenic addition and a special heat treatment to prevent dezincification by soft, acidic, water supplies. Sometimes the term is applied to arsenical, aluminum or admiralty brasses which also have arsenic additions. These alloys need no special heat treatment since no beta phase is present.
D-fibre – It is a specialized optical fibre whose cross-section resembles the letter ‘D’. It is made by polishing or etching away a portion of the outer cladding until it is very close to the light-carrying core. This flat surface allows external materials to interact directly with the fibre’s evanescent field.
D-glass – It is a high boron content glass made especially for laminates needing a precisely controlled dielectric constant.
DH (Dortmund Hoder) degassing process – It is a vacuum degassing process used in steelmaking to remove dissolved gases from molten steel. It is particularly effective for removing hydrogen and nitrogen, which can negatively impact steel properties. In DH degassing process, a small quantity around 10 % to 15 % of the total mass of liquid steel is degassed at a time. The process is repeated until the needed level of degassing is achieved. The DH degassing process has a cylindrical vessel with a single snorkel and operates by repeatedly sucking the liquid steel into the vacuum chamber and then releasing it back into the ladle. The DH chamber is equipped with heating facility, alloying addition arrangement and exhaust system. Bottom of the cylindrical vessel is provided with a snorkel which can be dipped into the liquid steel. The upper portion of the DH chamber is lined with the fireclay bricks and the lower portion with the alumina bricks. Snorkel is lined with higher quality of alumina bricks. The length of the snorkel is sufficiently large to realize the effect of atmospheric pressure on rise of steel in the snorkel. The important steps for operation the DH degassing process are (i) DH chamber is preheated and lowered in the ladle so that snorkel tip dips below the liquid steel surface, (ii) the evacuated chamber is moved up and down so that steel enters the chamber, (iii) the chamber is moved for 50 times-60 times with a cycle time of 20 seconds, (iv) adequate degassing is possible in 20 cycles to 30 cycles (iv) a layer of slag is kept in the ladle to minimize heat losses, and (v) the DH degassing process can operate with lower superheats since DH unit has heating facility.
Diabase – It is a common basic igneous rock usually occurring in dykes or sills.
Diabatic – It is a process in which external heat is gained or lost by the system.
Diacetin – It is glycerol diacetate. It is a clear, odourless chemical ester made by reacting glycerol with acetic acid. It functions as a high-boiling solvent, polymer plasticizer, and fuel oxygenate additive to improve material performance and combustion properties.
Diagnosis – It is used in several different disciplines, with variations in the use of logic, analytics, and experience, for the determination of cause and effect. In systems engineering and computer science, it is typically used to determine the causes of symptoms, mitigations, and solutions.
Diagnostic algorithm – It is a systematic, step-by-step mathematical or logical procedure designed to analyze system data, detect anomalies (fault detection), and pinpoint the exact source or nature of a malfunction (fault isolation and identification). It functions by mapping real-time sensor measurements against an expected baseline or system model to evaluate the health of a physical asset, software system, or process.
Diagnostic coverage – It is the fraction of dangerous hardware failures detected by automatic online self-tests. It is expressed as a ratio of the dangerous detected failure rate to the total dangerous failure rate. It the extent to which a diagnostic system can identify failures within a system, typically expressed as a percentage. It can be categorized into levels such as 60 %, 90 %, and 99 %, with each level needing different testing samples and analytical approaches to establish its effectiveness.
Diagnostic devices – These are smart instruments capable of diagnosing both overt and covert component failures by monitoring performance, predicting process changes, and providing powerful diagnostic information to optimize operation and maintenance. They can detect issues such as sensor drift and component deterioration while offering insights into the process through advanced communication and networking capabilities.
Diagonal basis – It is a set of basis vectors made entirely of eigenvectors for a specific linear operator or matrix. When a person uses this basis, the matrix representation of that linear operator becomes a diagonal matrix, meaning all entries off the main diagonal are zero.
Diagonal bracing – It is a a structural support system where bars, beams, or cords are placed at an angle across a rectangular frame to form triangles. This configuration stops side-to-side movement, prevents the frame from twisting or collapsing, and safely shifts forces down to the ground.
Diagonal channel – It very frequently refers to a diagonal-conduction-wall (DCW) magneto-hydrodynamic (MHD) power generator channel where slanted, electrically connected electrode modules suppress Hall currents while simplifying external electrical circuits.
Diagonal component – It normally refers to an inclined structural brace (like a web member in a truss) that handles lateral forces, or a mathematical element residing on the principal axis of a matrix. It also refers to specific elements of the covariance matrix which correspond to the same variables in a stochastic process, and in the context of diffusion processes, diagonal components can be represented through an expectation involving joint probability densities and singular densities related to initial positions.
Diagonal crack – It is an inclined fracture (typically at a 30-degree to 45-degree angle) caused by combined shear and tensile stresses. These structural cracks occur when loads or ground movements exceed the material’s tensile strength, frequently appearing near beam supports, wall corners, or around openings like doors and windows.
Diagonal dominance – It means that in a square matrix, the magnitude of the diagonal entry in each row is higher than or equal to the sum of the magnitudes of all other non-diagonal entries in that same row.
Diagonal edge – It is also called diagonal line segment. It connects two opposite corners or vertices of a shape which do not sit on the same outer side. It creates a slanted path across a structure, surface, or material rather than running straight up, down, or across.
Diagonal matrix – It is a square matrix where all elements outside the main diagonal are zero. Non-zero values exist only on the line from the top-left to the bottom-right corner. It decouples multi-variable differential equations, simplifying system analysis.
Diagonal plane – It is a flat surface which cuts through a 3D object or coordinate system at an angle which is neither parallel nor perpendicular to the standard horizontal, vertical, or principal orthogonal axes.
Diagonal rolling – It is a special case of cross rolling. The mechanism of plastic deformation is here a similar one. However, work rolls axes are not parallel, but skew. Hence, the rolling stock not only rotates, but also feeds forward in the direction of its longitudinal axis, because of the skew axes of the rolls. This mode of rolling is used for the rolling of seamless tubes. It is the popular method for the production of hollow semi-finished products.
Diagonal rolling mill – It is a type of rolling mill where the rolls are arranged at an angle to the direction of the metal being rolled. This arrangement is used to achieve specific shape and thickness changes in the metal, often with the goal of producing products with complex cross-sections.
Diagonal structure – It is frequently called a diagrid (diagonal grid). It is a framework of intersecting slanted metal, concrete, or wooden beams. Instead of relying on traditional vertical columns, it uses triangular modules to handle both gravity loads and sideways wind or earthquake forces through axial tension and compression.
Diagonal strut – It is an inclined structural member or a conceptual internal compression path designed to resist pushing forces (compression) along a diagonal axis. It stabilizes frames against sideways loads like wind or earthquakes.
Diagonal tension – It is a tensile stress state occurring at an angle (normally around 45-degree) inside a structural member because of the shear forces. It causes brittle, inclined cracking in concrete beams or wrinkled tension fields in thin aerospace webs.
Diagram – It is a drawing, sketch, plan, or chart which makes something clearer or easier to understand.
Dial gauge – It is also known as a dial gauge indicator. It is a precision instrument employing numerical indicators and an internal mechanism to measure various components or objects accurately. A dial gauge is used to measure small linear displacements or dimensional variations with high precision and accuracy.
Dial indicator – It is a precision measuring tool used to measure small linear distances, surface variations, and part alignment by translating a probe’s physical movement into an amplified visual reading on a circular dial.
Dialkyl carbonate – It is a chemical compound containing two alkyl chains bound to a carbonate group (OC(=O)OR2). In chemical and process engineering, these molecules, such as dimethyl carbonate (DMC) and diethyl carbonate (DEC), function as safe, green solvents, fuel additives, and vital reactive intermediates for synthesizing plastics, pharmaceuticals, and lithium-ion battery electrolytes.
Diallyl phthalate – It is a colourless, oily liquid which is an ester of phthalic acid and allyl alcohol. It is a thermosetting resin with good electrical insulation, heat resistance, and water resistance properties. It is normally used as a plasticizer and carrier for catalysts and pigments, particularly in applications like laminating compounds and electrical parts.
Dialog box – It is a temporary graphical window used by programmes to communicate information to users and request specific inputs or decisions before proceeding.
Dialog design – It is the process of structuring the bidirectional exchange of information, commands, and feedback between a human user and a computer system. Its core goal is to make system navigation, data input, and task execution intuitive, efficient, and error-free.
Dial thermometer – It is a rugged, mechanical temperature gauge which indicates heat levels using a pointer moving across a circular scale. It is widely used to monitor the temperatures of furnaces, liquid metals, cooling baths, and heat-treating ovens without needing external power.
Diamagnetic material – It is a material whose specific permeability is less than unity and is hence repelled weakly by a magnet. It is a substance which is weakly repelled by a magnetic field. When exposed to an external field, it induces an internal magnetic moment in the exact opposite direction. It has a negative magnetic susceptibility and does not retain any magnetism once the external field is removed.
Diameter – In geometry, a diameter of a circle is any straight-line segment which passes through the centre of the circle and whose endpoints lie on the circle. It can also be defined as the longest chord of the circle. Both definitions are also valid for the diameter of a sphere.
Diameter application – It is a protocol built on top of the diameter base standard which supports specific requirements by creating new commands and attribute-value pairs (AVPs), while also benefiting from the capabilities of the diameter base protocol. These applications can inherit elements from existing applications and can include vendor-specific implementations.
Diameter base protocol – It is the foundational standard framework providing authentication, authorization, and accounting (AAA) services. In mechanical engineering, a base diameter refers to the specific linear dimension measured at the lowest supporting or referencing plane of a geometric or physical feature.
Diameter base standard – It is the core computer networking specification which provides an authentication, authorization, and accounting (AAA) frame-work for modern mobile and IP (internet protocol) networks. It sets the base-line rules for message handling, security, and transport.
Diameter, channel – Channel diameter is the actual inner diameter for circular fluid conduits. For non-circular channels (like rectangular ducts or C-channels), engineers use the hydraulic diameter (Dh = 4A/P, where ‘A’ is cross-sectional area and ‘P’ is wetted perimeter) as the standard definition equivalent to diameter in calculations.
Diameter core – It refers to a cylindrical sample got from a structure, typically using a coring bit, where the nominal diameter of the bit indicates the outer size, but the actual core diameter is slightly smaller, such as a 100 millimeters bit yielding a core of 95 millimeters. The selection of the diameter core is important for meeting specific testing requirements, including the length-to-diameter ratio.
Diameter distribution – It a statistical way to show how different sizes or widths spread across a group of items, like tree trunks in a forest or tiny dust pieces in the air. It tells us how many items fall into each size group.
Diameter, hole – Hole diameter is the straight-line measurement across the widest circular part of an internal cylindrical feature, marked by the diameter symbol (phi). It defines the physical size needed for parts like fasteners, pins, or shafts.
Diameter, pipe – Pipe diameter is the measurement across a pipe’s circular cross-section. It is split into three main types namely inside diameter (ID) for fluid capacity, outside diameter (OD) for physical clearance, and nominal diameter (NPS/DN) as a standardized shorthand name rather than an exact physical number. Pipe diameter considerably influences the performance of geothermal heat exchangers (GHE) by affecting heat transfer area, thermal resistance, and overall system efficiency.
Diameter protocol – It is an advanced authentication, authorization, and accounting (AAA) network standard. Built by the IETF (internet engineering task force) as a reliable replacement for legacy RADIUS (remote authentication dial-in user service), it handles user verification, resource access limits, and usage tracking over TCP (transmission control protocol) or SCTP (stream control transmission protocol) transport layers in 4G, 5G, and IMS (IP multimedia sub-system) mobile core architectures.
Diameter ratio – It is frequently called the beta ratio. It is the mathematical proportion of a smaller internal circular opening to a larger enclosing or reference circular structure, defined as beta = d / D, where ’d’ is the bore or inner diameter and ‘D’ is the main pipe or outer diameter.
Diameter reduction – It normally refers to size reduction (crushing or milling) to decrease particle diameter, or dimensional reduction in manufacturing (e.g., machining, drawing) to shrink the physical cross-section of a rod or pipe.
Diameter tolerance – It is the permissible limit of variation in the diameter of a cylindrical or spherical feature. since no manufacturing process is perfect, engineers specify an acceptable size range, or ‘zone’, within which a manufactured part is required to fall to ensure it fits and functions correctly. Diameter tolerances are typically represented in engineering drawings and schematics in a few standard ways namely bilateral tolerance, unilateral tolerance, and limit dimensions.
Diameter, tube – It is a tube’s diameter. It is specified by its exact outside diameter (OD) and wall thickness, unlike a pipe which uses a nominal inside diameter. The inside diameter (ID) of a tube is calculated by subtracting twice the wall thickness from the precise outside diameter.
Diameter, wellbore – Wellbore diameter the internal width or size of the excavated or drilled hole in the ground (also called a borehole). It matches the outer size of the drill bit and shrinks in stages as steel casing pipes are placed deeper into the earth.
Diametral compression test – It is also known as the Brazilian test or indirect tensile test. It is a mechanical testing method where a cylindrical or disc-shaped material is compressed across its diameter until it splits. It is mainly used to evaluate the tensile strength of brittle or difficult-to-machine materials, such as pressed metal powders, metal matrix composites, and hard ceramics.
Diametral pitch – It is the ratio of the number of teeth on a gear to its pitch diameter, expressed as the number of teeth per inch of pitch diameter. It defines the size and spacing of gear teeth in imperial (inch-based) systems.
Diametric projection – In diametric projection, all dimensions along two axes are drawn to ‘true size’ The dimensions along the third axis are halved. This projection is preferred when one view of the object is to be emphasized than the other two views (i.e., when one view is of more interest than the other views).
Di-ammonium phosphate – It is a highly versatile inorganic salt used mainly as a flame retardant to fire-proof protective clothing for foundry workers. It is also used a chemical binder component in specialized ceramic slurries for investment casting. Di-ammonium phosphate (DAP) is also being used as phosphorus fertilizer. It is a water-soluble, white crystalline salt produced by reacting ammonia with phosphoric acid. The chemical formula is (NH4)2HPO4.
Diamond – It is the hardest known mineral. It is composed of pure carbon. Low-quality diamonds are used to make bits for diamond drilling in rock.
Diamond bit – It is a specialized rotary cutting tool embedded with industrial-grade diamond particles on its cutting face. It grinds and abrades through extremely hard geological and structural materials, such as granite, concrete, and ceramics, where traditional steel or carbide bits fail.
Diamond coating – It is an ultra-thin film of carbon-based material applied to a substrate’s surface to maximize hardness, wear resistance, thermal conductivity, and chemical inertness. It transforms standard base metals into high-performance components.
Diamond crystal – It is a rigid three-dimensional network of sp3-hybridized carbon atoms linked by strong covalent bonds in a face-centered cubic lattice. This repeating atomic arrangement gives the material extreme hardness, high thermal conductivity, and electrical insulation.
Diamond cutting edge – It is the ultra-sharp working boundary of a precision machining tool made from single-crystal, poly-crystalline (PCD), or chemical vapour deposition (CVD) diamond. It utilizes the world’s hardest material to shear or grind hard, brittle materials with nanometer-level surface accuracy and minimal tool wear.
Diamond deposit – It refers to the thin film or layer of diamond material grown and applied onto a solid substrate using advanced manufacturing processes, most notably chemical vapour deposition (CVD). It is the most common technique used for diamond growth.
Diamond dies – These are specialized manufacturing tools used mainly in the wire drawing process. They feature a highly polished, precisely engineered diamond core (natural or synthetic) with a conical hole used to pull and reduce metal rods into thinner, highly precise wires.
Diamond disc – It is a precision circular tool with industrial diamond particles bonded to its rim. It grinds and cuts hard, brittle materials like concrete, stone, and ceramics through high-speed friction rather than using traditional teeth.
Diamond drill – It is a rotary type of rock drill which cuts a core of rock that is recovered in long cylindrical sections, two centimeters or more in diameter.
Diamond driller – It means a person who operates a diamond drill.
Diamond drilling – It is drilling method which gets a cylindrical core of rock by drilling with an annular bit set with diamonds.
Diamond enhanced inserts – These are ultra-hard cutting, drilling, and wear-resistant tools. They consist of a tough core (typically tungsten carbide) infused or coated with synthetic diamond grains. This design provides superior impact resistance, thermal stability, and wear life.
Diamond film – It is a carbon-composed film, normally deposited by chemical vapour deposition or related process, which has three characteristics namely (i) a crystalline morphology which can be visually discerned by optical microscopy, (ii) a single-phase crystalline structure identifiable by x-ray and / or electron diffraction, and (iii) a Raman spectrum typical for crystalline diamond. The sharpness of the sp3 carbon-carbon bonding peak (wave-number 1,332 cm-1) is frequently used to determine the perfection of the film.
Diamond grinding – It is a precision material-removal process which uses industrial diamond grains bonded to a wheel, disc, or blade. Since diamond is the hardest bulk material, this method cuts, smooths, or profiles extremely hard, brittle, or tough surfaces without inducing heavy structural damage.
Diamond grit – It is an industrial abrasive made of natural or synthetic diamond particles embedded in tools like grinding wheels, saws, and drills to cut, shape, or polish hard materials. Each particle acts as a microscopic cutting edge which shears away material mechanically.
Diamond-like carbon – It is an amorphous carbon material which combines the extreme hardness of a diamond with the low-friction lubricity of graphite. It is mainly applied as a protective thin-film coating to metals, plastics, and ceramics to improve durability, reduce wear, and prevent corrosion.
Diamond-like carbon (DLC) coatings – These are a class of amorphous, metastable carbon-based thin films which combine the extreme hardness of diamond with the low-friction lubricity of graphite. Applied to metals, tools, and mechanical components, they reduce wear, prevent corrosion, and lower the coefficient of friction.
Diamond-like film – It is a hard, non-crystalline carbon film, which is normally grown by chemical vapour deposition or related techniques, and which contains predominantly sp2 carbon-carbon bonds.
Diamond mines – These are industrial excavation sites designed to locate, extract, and process diamond-bearing ore (mainly kimberlite and lamproite volcanic pipes or secondary alluvial deposits) from the earth’s crust. These operations use heavy machinery, geo-technical engineering, and materials processing to recover rare gemstone and industrial-grade carbon crystals.
Diamond mode – It refers to a non-axisymmetric buckling mode observed in cylindrical shells, characterized by the formation of ripples in both axial and circumferential directions, leading to complex folding into triangular segments during crushing.
Diamond phase – It refers to the tetrahedral sp3-bonded crystalline carbon structure which is metastable under ambient conditions. It provides extreme hardness, high thermal conductivity, and wide-bandgap electronic properties used in cutting tools, coatings, and high-frequency semiconductor devices.
Diamond polishing – It is a high-precision manufacturing process used to create ultra-smooth, mirror-like surface finishes on hard materials, including single-crystal, poly-crystalline, and CVD (chemical vapour deposition) diamond layers, by removing microscopic layers of material using fine diamond grit, pastes, or specialized thermo-chemical reactions.
Diamond pyramid hardness test – It is also known as Vickers hardness test which is a micro-indentation hardness test employing a 136-degree diamond pyramid indenter (Vickers) and variable loads, enabling the use of one hardness scale for all ranges of hardness–from very soft lead to tungsten carbide.
Diamond pyramid number – It is system of assigning values to metals quantifying their hardness.
Diamond tool – It is a diamond, shaped or formed to the contour of a single-point cutting tool, for use in precision machining of non-ferrous or non-metallic materials. It is also an insert made from poly-crystalline diamond compacts.
Diamond tooling – It refers to cutting, grinding, or drilling instruments which use synthetic industrial diamonds as the main abrasive or cutting edge. These tools are highly valued across several industries for machining extremely hard, abrasive, or brittle materials like stone, concrete, and glass. In manufacturing, powder metallurgy is a main method used to produce these tools. It involves mixing synthetic diamond grit with metallic powders (such as cobalt, iron, nickel, or bronze). This mixture is then subjected to extreme heat and pressure in a process known as sintering to fuse the metal into a solid, durable bond.
Diamond turning – It is an ultra-precision machining process which uses a single-point natural or synthetic diamond tool on a computer numerical control (CNC) lathe to cut rotationally symmetric or complex freeform shapes with nano-metric surface finish and sub-micron dimensional accuracy.
Diamond turning machine – It is an ultra-precision lathe utilizing a single-crystal natural or synthetic diamond-tipped cutting tool to machine components with nano-metric surface finish and sub-micrometer form accuracy.
Diamond wheel – It is a grinding wheel in which crushed and sized industrial diamonds are held in a resinoid, metal, or vitrified bond.
Diaphragm – It is a porous or permeable membrane separating anode and cathode compartments of an electrolytic cell from each other or from an intermediate compartment. It is also universal die member made of rubber or similar material used to contain hydraulic fluid within the forming cavity and to transmit pressure to the part being formed.
Diaphragm actuator – It is a pneumatic mechanical device which converts air pressure signals into linear motion to operate and control industrial process valves. It uses a flexible, pressure-sensitive membrane to move an internal stem against a counteracting spring.
Diaphragm compressor – It is a type of displacement compressor which utilizes a flexible diaphragm to compress a gas. Unlike traditional piston compressors, the diaphragm’s movement, driven by a mechanical or hydraulic mechanism, is what changes the volume within the compressor chamber.
Diaphragm displacement – It is the physical movement or deflection of a flexible thin membrane (diaphragm) when subjected to a differential pressure, mechanical force, or fluid volume change. It is used to measure pressure, pump fluids, or analyze structural floor / roof deflection under lateral loads.
Diaphragm forming – It is a method of simultaneously consolidating and forming thermoplastic composites in which the lay-up is sandwiched between two heat-formable sheets (frequently superplastic aluminum sheets) and placed under gas pressure in a press to form and consolidate the desired shape.
Diaphragm gauge – It is a mechanical pressure instrument which uses a thin, flexible metal membrane (diaphragm) to measure fluid pressure. When process media pushes against the flexible disc, the resulting elastic deflection moves a connected linkage, gear, or electronic sensor to display a precise pressure reading on a calibrated scale.
Diaphragm pressure sensor – It is an engineering device which uses a thin, flexible membrane to measure gas or liquid pressure. When pressure pushes on the membrane, it bends. The sensor turns this small movement into an electrical or mechanical signal.
Diaphragm shell moulding machine – It is an automated foundry machine which produces thin, high-precision sand and resin moulds for metal casting. It forces a flexible membrane (the diaphragm) against the mould material, using air or hydraulic pressure to evenly compress resin-coated sand over a heated metal pattern.
Diaphragm system – It typically refers to a horizontal structural element, such as a floor or roof, which transmits lateral wind and earthquake loads to vertical resisting components like shear walls or frames. It can also denote a flexible membrane used in mechanical devices to separate media or convert pressure.
Diaphragm valve – A diaphragm valve is a linear motion valve which is used to start, regulate, and stop fluid flow. The name is derived from its flexible disk, which mates with a seat located in the open area at the top of the valve body to form a seal. Diaphragm valves are, in effect, simple ‘pinch clamp’ valves. A resilient, flexible diaphragm is connected to a compressor by a stud moulded into the diaphragm. The compressor is moved up and down by the valve stem. Hence, the diaphragm lifts when the compressor is raised. As the compressor is lowered, the diaphragm is pressed against the contoured bottom in the straight through valve or the body weir in the weir-type valve.
Diaphragm wall – It is also called slurry wall. It is a deep, underground reinforced concrete wall constructed panel-by-panel. It acts as a structural retaining wall and a watertight groundwater barrier during deep excavations, such as for metro stations, basements, and dams.
Diaryliodonium salts – These are stable, colourless, crystalline hypervalent iodine(III) compounds which act as highly photo-sensitive cationic photo-initiators and versatile arylating agents for advanced polymer and material manufacturing. Diaryliodonium salts are stable at room temperature and are capable of initiating cationic polymerization upon UV (ultra-violet) irradiation. They undergo fragmentation reactions that produce reactive species, including Bronsted acids, when exposed to light.
Diaspore – It is a naturally occurring aluminum oxide hydroxide mineral with the chemical formula alpha-AlO(OH). It is a main constituent of bauxite (the principal ore of aluminum) and is extensively used to manufacture high-alumina refractory bricks and kiln linings because of its high melting point and thermal shock resistance.
Diaspore clay – It is a natural rock comprised primarily of the mineral diaspore (a hydrated aluminum oxide, AlO(OH)) bonded together by fireclay. It is a highly aluminous material valued for its excellent refractory properties.
Dia-tester – It is a renowned line of universal and macro-hardness testing machines. It is used to precisely measure a material’s resistance to plastic deformation by pressing a standardized indenter into its surface under a specific load.
Diatomaceous earth – It is also known as diatomite. It is a naturally occurring, soft, silicious, sedimentary rock which can be crumbled into a fine white to off-white powder. It has a particle size ranging from more than 3 millimeters to less than 1 micrometer, but typically 10 micrometers to 200 micrometers. Depending on the granularity, this powder can have an abrasive feel, similar to pumice powder, and has a low density as a result of its high porosity. The typical chemical composition of oven-dried diatomaceous earth is 80 % to 90 % silica, with 2 % to 4 % alumina (attributed mostly to clay minerals), and 0.5 % to 2 % iron oxide.
Diatomic – It means composed of two atoms, of the same or different elements.
Diatomic gas – It is a gas whose molecules are composed of two atoms bound together. These atoms can be identical (homonuclear like oxygen and nitrogen or different (heteronuclear like carbon mono-oxide). Because of their dual-atom structure, they store energy through translational, rotational, and vibrational modes, which directly influences heat capacity and energy transfer in thermal systems.
Diatomic molecule – It is a molecule composed of only two atoms, of the same or different elements.
Diatomite – It is also called diatomaceous earth. It is a light-weight, sedimentary rock composed of fossilized micro-algae (SiO2). It is mainly valued for its high porosity, low thermal conductivity, and chemical inertness, serving as a premium thermal insulator and mould-release agent.
Di-calcium aluminate – It is a specialized calcium aluminate with the chemical formula Ca2Al2O5. It typically adopts a crystalline structure known as brownmillerite. It is mainly recognized as a phase within hydraulic cements and an advanced ceramic material studied for its optical, electrical, and oxygen-ion conductive properties.
Di-calcium ferrite – It is a crystalline mixed-metal oxide with the chemical formula Ca2Fe2O5. It is mainly recognized as a fundamental structural phase in metallurgical slags (especially steel slag) and is frequently investigated as an oxygen carrier for chemical looping syngas and hydrogen production.
Di-calcium silicate It has chemical formula Ca2SiO4 or 2CaO.SiO2. It is an important inorganic chemical compound containing calcium, silicon, and oxygen. It is widely known as belite in the cement industry. It is one of the four principal mineral compounds found in standard Portland cement.
Di-carboxylic acid – It is an organic compound which contains two carboxyl functional groups (−COOH). Its general molecular formula is HOOC−R−COOH, where ‘R’ represents an aliphatic or aromatic carbon chain. Because of the dual acidic groups, they act as diprotic acids and are necessary in both biological processes and industrial manufacturing.
Dice value – It is a statistical metric used to measure the similarity or overlap between two spatial regions, binary sets, or image segmentation masks. Dice values refer to a quantitative measure used to evaluate segmentation performance, defined as 2 times the intersection of segmented and ground truth regions divided by the sum of the pixel sets of both regions, expressed as a percentage. A larger Dice value indicates better segmentation performance, with Dice global applied across all volumes in a dataset and Dice per-case averaged over individual volumes.
Di-chloro-di-phenyl-tri-chloro-ethane – It is commonly known as DDT. It is a colourless, tasteless, and almost odourless crystalline chemical compound. It is an organochloride. Originally developed as an insecticide, it became infamous for its environmental impacts.
Di-chloro-ethylene (DCE) – It is used to make certain plastics, packaging materials, and flame-retardant coatings. Typically, it is a degradation product of other chlorinated solvents.
Dichroic mirror – It is an optical device which reflects specific wave-lengths of light while transmitting others, frequently used in setups where precise control of light paths is needed to prevent unwanted beam leakage or attenuation.
Dichromate treatment – It is a chromate conversion coating produced on magnesium alloys in a boiling solution of sodium dichromate.
Dictionary learning – It is a machine learning method which builds an optimal set of basic building blocks, called atoms, from training data so that complex signals or images can be accurately represented using only a few of those atoms at a time.
Dictionary size – It refers to the total number of basic signal patterns, wave-form elements, or structural entries, called atoms, contained within a sparse representation or data compression dictionary. It directly controls reconstruction accuracy and computational load.
Dictionary vectors – These are elements in a translation-invariant dictionary which are optimized for applications such as noise removal and super-resolution in image processing, typically represented as small patches of pixels. These vectors can also reflect structures similar to directional wavelets and biological responses in visual processing.
Didymium – It is a natural mixture of the rare-earth elements praseodymium and neodymium, frequently given the quasi-chemical symbol Di.
Die – It is a specialized, customized tool or mould used to cut, shape, or form materials, very frequently metals, under extreme pressure or force. It acts as the ‘female’ counterpart to a male ‘punch’, working together to alter the metal’s physical profile. It is a tool, normally containing a cavity, which imparts shape to solid, molten, or powdered metal mainly because of the shape of the tool itself. It is used in several press operations (including blanking, drawing, forging, and forming), in die casting, and in forming green powder metallurgy compacts. Die-casting and powder metallurgy dies are sometimes referred to as moulds.
Die angle – It defines the specific taper, slope, or entry angle built into a forming tool (die). It determines how metal or plastic flows through, is sheared, or is released from the tooling.
Die aperture geometry – It refers to the specific shape, size, and dimensional profile of an opening in an extrusion, stamping, or moulding die. It dictates the final cross-sectional profile, flow characteristics, and structural integrity of the manufactured component or material.
Die assembly – It consists of the parts of a die stamp or press which hold the die and locate it for the punches.
Die block – It is a block, frequently made of heat-treated steel, into which desired impressions are machined or sunk and from which closed-die forgings or sheet metal stampings are produced using hammers or presses. In forging, die blocks are normally used in pairs, with part of the impression in one of the blocks and the rest of the impression in the other. In sheet metal forming, the female die is used in conjunction with a male punch.
Die body – It is the stationary or fixed part of a powder pressing die.
Die breakage – It normally refers to the cracking, chipping, or fracturing of a metal die (a specialized tool used for cutting, shaping, or stamping materials) caused by fatigue, excessive pressure, or material defects. It results in either tool failure or ruined end products.
Die, casting – It is metal form(s) used to produce a die casting, a lost foam pattern, or a wax pattern. It is a metal block used in the die casting process, incorporating the cavity or cavities that form the cast component, the molten metal distribution system, and means for cooling and ejecting the casting.
Die casting – It is a casting made in a die. It is a process where molten metal is forced under high pressure into a metal mould (die) to create a desired shape, and then the metal solidifies within the mould. This process allows for the creation of intricate, high-precision metal parts with smooth finishes.
Die casting, cold chamber – It is a manufacturing process where molten metal is ladled from an external furnace into an unheated injection chamber (cold chamber). A hydraulic plunger forces the metal into a steel die under extreme pressure to form high-strength, precision metal parts.
Die casting, gravity – It is the term used in for producing a casting by pouring molten metal (gravity pouring) into a metal mould, with no application of pressure. It is also called as the permanent mould casting process.
Die casting, hot chamber – It is a high-speed process where the melting furnace and injector mechanism are integrated. A plunger forces molten, low-melting-point alloys (like zinc or magnesium) directly into a reusable steel mould under high pressure. It is designed for mass-producing small, intricate parts.
Die casting machine – It is a device used in the die casting process to force molten metal into a die cavity under high pressure, enabling the production of complex metallic components efficiently and at low cost for mass production.
Die casting, pressure – It is a casting made in a metal mould (set of metal dies) in which the metal is injected under high pressure, by either cold-chamber or hot-chamber die casting machines. It is also used for simply die casting. High-pressure die casting and low-pressure die casting are terms normally used to differentiate between the two processes which are also called die casting and low-pressure permanent moulding respectively.
Die casting process – It is a metal casting process which is characterized by forcing of liquid metal under high pressure into a mould cavity. The mould cavity is created using two hardened dies made of tool steel. These dies are machined into shape and work similarly to an injection mould during the process. Majority of die castings are made from specifically zinc, copper, aluminum, magnesium, lead, pewter (alloy of tin, copper and antimony) and tin-based alloys. Die castings of ferrous metal are also possible.
Die cavity – It is the machined recess which gives a forging or stamping its shape. It is the hollow space or recessed geometric impression inside a die or mould. Raw material, such as molten metal, plastic, or sheet metal, is forced, pressed, or injected into this cavity to shape it into the desired final product.
Die check – It is a crack in a die impression because of the forging and thermal strains at relatively sharp corners. Upon forging, these cracks become filled with metal, producing sharp ragged edges on the part. Normal die wear is the gradual enlarging of the die impression because of the erosion of the die material, normally occurring in areas subject to repeated high pressures during forging.
Die checking – It is the process of inspecting, validating, and testing industrial dies (the specialized moulds or cutting tools used for stamping, casting, or extrusion). It ensures dimensional accuracy, surface integrity, and structural reliability before and during mass production to prevent costly defects and downtime.
Die chill – It is a heat-extracting insert (typically metallic or graphite) placed within or against a die cavity. Its purpose is to accelerate the localized cooling.
Die chilling – It refers to the rapid extraction of heat from a heated workpiece through its contact with a colder mold or forming tool (the die). This rapid cooling rate directly dictates the material’s micro-structure, mechanical strength, and final dimensional accuracy during forming or solidification.
Die clearance – It is the intentional gap or space between the cutting edge of a punch and the opening of a die. It is vital in metal stamping and shearing operations to provide leverage for the material to fracture cleanly, prevent the tooling from binding, and ensure precise part dimensions. It is the clearance between a mated punch and die. It is normally expressed as clearance per side. It is also called clearance or punch-to-die clearance.
Die-closing swaging – It is frequently called rotary swaging or radial forging. It is a metal forming process where two or more split dies rapidly close and open to hammer a work-piece radially. This continuous compressive force reduces the diameter of tubes or solid rods, deforming the metal without removing any material.
Die closure – It is a term frequently used to mean variations in the thickness of a forging.
Die-closure tolerance – It is frequently called thickness tolerance. It is a technical specification in closed-die manufacturing (like forging or die casting) which defines the allowable variation in the thickness of a part across its fundamental parting line.
Die coating – It is also called die release agent. It is a semi-permanent ceramic or chemical layer applied to the inner walls of a permanent metal mould. Die coating protects the surface of the die from molten metal and prevents the erosion from occurring.
Die contact time – It refers to the duration a material, billet, or component physically interacts with a forming or shaping tool (the die) during a manufacturing cycle. In processes like forging, it defines the chilling time of the work-piece, while in extrusion, it describes the duration the molten material remains in the die channel.
Die cooling – It refers to the active removal of heat from a manufacturing mould (die) to regulate its temperature, control the solidification rate of the injected material (such as molten metal or plastic), and prevent structural defects like warping or porosity. Die cooling is an indispensable practice in cyclic manufacturing processes, like high-pressure die casting (HPDC), metal stamping, and injection moulding, to optimize production cycles and protect tooling from thermal fatigue.
Die cooling and lubrication – It is the engineered process of applying fluids and managing thermal paths in forming processes (like stamping, forging, or die casting). Its dual purpose is to dissipate extreme operational heat and reduce friction, preventing die wear, thermal fatigue, and work-piece defects.
Die cracking – It refers to the fracture or splitting of a ‘die’, which typically applies to brittle silicon micro-chips (semi-conductors) or metal manufacturing/casting tools. In micro-electronics, die cracking occurs when mechanical or thermo-mechanical stresses exceed the silicon’s fracture strength, causing the material to split, laminate, or fracture. In tooling and manufacturing, die cracking refers to the structural breakdown of the tool itself.
Die cushion – It is a press accessory placed beneath or within a bolster plate or die block for providing an additional motion or pressure for stamping or forging operations. It is actuated by air, oil, rubber, springs, or a combination of these.
Die deformation – It refers to the intentional plastic shaping of a material using a solid tool (the die). It also describes the unintended physical distortion or wear of the die itself caused by the extreme forces, temperatures, and mechanical stress experienced during manufacturing processes like forging, extrusion, or stamping.
Die design – It is a specialized engineering discipline focused on creating precision tools and moulds used in manufacturing processes to shape materials into desired forms. This complex field combines principles of mechanical engineering, materials science, and industrial design to develop dies which can efficiently and accurately produce components through different manufacturing methods such as stamping, forging, casting, and extrusion. The process involves detailed analysis of material behaviour, stress distribution, thermal characteristics, and wear patterns to ensure optimal performance and longevity of the die. Engineers are required to consider factors such as material flow, draft angles, shrinkage allowances, parting lines, and ejection mechanisms while maintaining strict dimensional tolerances. The evolution of die design has been considerably influenced by technological advancements, particularly computer-aided design (CAD) and simulation software, which allow designers to optimize their designs through virtual testing before physical production. Modern die design incorporates sophisticated cooling systems, innovative materials, and precise surface treatments to improve production efficiency and product quality.
Die drawing – It is a computer aided design (CAD) drawing of the extrusion die showing exact detail of the shape of the profile.
Die, extrusion die – It is the hardened steel aperture through which a heated extrusion billet is pushed to form an extruded profile shape. There are 3 types of die namely (i) flat die for extruding solid shapes, (ii) porthole die for extruding hollow shapes, which leaves one or two ‘weld’ seams along the length of the extrusion so tube produced in this way is called welded tube, and (iii) flat die with mandrel for extruding seamless hollow shapes and seamless tube.
Die failure mode – It is the specific way a component, process, or physical part fails to perform its intended function. It describes how something breaks or malfunctions physically (e.g., fractured, leaking, or worn out), rather than why it happened or the consequences of it. Understanding these failure modes helps engineers identify root causes and prevent system breakdowns.
Die finish – It normally refers to the surface finish of the die itself (the mould used to shape materials), as well as the surface finish of the part produced by the die. The surface texture and quality in both contexts are typically measured and defined by three main characteristics namely roughness, waviness, and lay.
Die forger hammers – These hammers are similar in operation to power-drop hammers but have shorter strokes and more rapid striking rates. The ram is held at the top of the stroke by a constant source of pressurized air, which is admitted to and exhausted from the cylinder to energize the blow.
Die, forging or extrusion – It is metal forms between which metal is forged or through which metal is extruded. The shapes of the dies control the form and shape of the finished parts.
Die forging – It is a forging which is formed to the needed shape and size through working in machined impressions in specially prepared dies. Based on the arrangements of dies, the process of forging can be (i) open die forging, and (ii) closed die forging.
Die forming – It is the shaping of solid or powdered metal by forcing it into or through the die cavity.
Die geometry – It defines the precise internal profile, angles, and dimensions of a manufacturing die. It acts as a template or mould dictating how materials are cut, shaped, or compressed. Accurate geometry ensures structural integrity, tight tolerances, and a longer tool life-span. For operations like wire drawing, the inner profile is normally divided into distinct geometric zones such as bell / entrance, approach angle, bearing area, and back relief.
Die hardness – It refers to a tool steel’s resistance to permanent surface indentation, scratching, or localized plastic deformation under applied stress. It is an important performance indicator for industrial dies and cutting tools, as it directly governs the material’s wear resistance and operational life-span.
Die heating – It refers to the process of pre-heating, regulating, or maintaining the temperature of a mould (die) before and during production. It prevents thermal shock, reduces material defects, and ensures the proper flow and forming of molten metals or plastics.
Die height – It is the distance between the fixed and the moving platen when the dies are closed.
Die holder – It is a plate or block, on which the die block is mounted, having holes or slots for fastening to the bolster plate or the bed of the press.
Die impression – It is the portion of the die surface which shapes a forging or sheet metal part. Die impressions refer to the precut, negative-profile cavities machined into a set of forging dies. When the upper and lower die halves are pressed together, these impressions act as a mould, forcing a heated or malleable material (like steel or aluminum) into a precise, desired shape.
Die insert – It is a relatively small die which contains part or all of the impression of a forging or sheet metal part and is fastened to the master die block. Die inserts are modular, replaceable components fitted into larger die blocks or moulds used for metal stamping, forging, or die casting. Instead of discarding or re-machining a massive, expensive die when a critical wear area or specific cavity shape deteriorates, engineers simply replace the smaller, localized insert.
Die insert fracture – It is the failure or cracking of a specialized, replaceable tool (insert) used within a larger die block during manufacturing processes like forging, extrusion, or die casting. It occurs when repeated mechanical stress or thermal cycling causes internal cracks which propagate into catastrophic structural separation.
Die land length – It is the length of the final, parallel straight section within a die opening. It acts as a flow restrictor that stabilizes material, controls exit speed, and dictates the final shape and surface quality of an extruded or stamped part.
Dielectric – It a material which is a poor conductor of electricity but effectively supports an electrostatic field, allowing for polarization under an applied electric field. Dielectric materials can exist in solid, liquid, or gas states and are normally used in applications such as capacitors and sensors.
Dielectric absorption – It is the tendency of a capacitor’s insulating material to retain a small residual electrical charge after being discharged. Also called ‘soakage’, the slow, time-delayed realignment of molecular dipoles causes a recovered voltage to build back up across the terminals.
Dielectric baking – It is a process used to rapidly cure sand cores and moulds using high-frequency electro-magnetic energy. By subjecting the non-conducting sand mixture (bound by thermo-setting resins) to a radio frequency (RF) or micro-wave electric field, the cores heat up uniformly from the inside out.
Dielectric constant – It is the ratio of the capacitance of an assembly of two electrodes separated solely by a plastic insulating material to its capacitance when the electrodes are separated by air.
Dielectric curing – It is the curing of a synthetic thermosetting resin by the passage of an electric charge (produced from a high-frequency generator) through the resin.
Dielectric discontinuity – It is an abrupt change or boundary between two adjacent media with different dielectric constants (permittivity). This mismatch alters electric field lines, causes wave reflections, and creates localized polarization charges at the interface.
Dielectric displacement – It is also called electric displacement field. It is a vector quantity measuring the quantity of free charge surface density within an electric field, specifically excluding the effects of bound charges in dielectric materials. It is mainly used to simplify Gauss’s law within insulators.
Dielectric elastomer – It is a compliant, smart polymer material sandwiched between two stretchable electrodes which acts as an electro-mechanical transducer. When a voltage is applied, electrostatic forces compress the film in thickness and expand it in area, enabling large reversible deformations used in soft robotics, and sensors.
Dielectric elastomer actuator – It is a smart, soft electromechanical transducer which converts electrical energy into mechanical movement. It consists of a thin, flexible insulating polymer film sandwiched between two stretchable, conductive electrodes. When a high voltage is applied, electrostatic forces compress the film’s thickness and expand its surface area.
Dielectric elastomer generator – It is a flexible, soft-transducer device which converts mechanical strain into electrical energy. It functions as a variable-capacitance generator. It consists of an elastic polymer film sandwiched between two stretchable, conductive electrodes. As external mechanical forces stretch and relax the soft membrane, the capacitance changes. This cyclic deformation work turns mechanical input into usable electrical power.
Dielectric film – It is a thin layer of an insulating material which polarizes when exposed to an electric field. It blocks electrical conduction while storing and releasing electrical energy. These films are used in microchips, capacitors, and solar cells to isolate circuits, reduce power loss, and control capacitance.
Dielectric fluid – It is a dielectric material in liquid state. Its main purpose is to prevent or rapidly quench electric discharges. Dielectric fluids are used as electrical insulators in high voltage applications, e.g. transformers, capacitors, high voltage cables, and high voltage switchgear. Its function is to provide electrical insulation, suppress corona and arcing, and to serve as a coolant.
Dielectric fluid unit – It refers to the specialized fluid used in electrical discharge machining (EDM) to control electrical sparks, cool the work-piece, and flush away eroded metal debris. The fluid acts as an insulator until the exact moment of spark discharge.
Dielectric function – It is a complex mathematical quantity describing how a material responds to an applied electric field or electro-magnetic wave. It links microscopic polarization changes to macroscopic energy storage and loss, varying with frequency.
Dielectric heating – It is the heating of materials by dielectric loss in a high-frequency electrostatic field.
Dielectric layer – It is an electrically insulating material placed between conductive parts to store electrical energy through polarization, prevent short circuits, and shape electric fields.
Dielectric loss – It is a loss of energy evidenced by the rise in heat of a dielectric placed in an alternating electric field.
Dielectric loss tangent – It is a dimensionless metric which measures how much electrical energy an insulating material turns into heat when exposed to an alternating electric field. It is defined mathematically as the ratio of the imaginary part of complex permittivity to its real part.
Dielectric material – It is a material which does not allow free flow of electric current.
Dielectric medium – It is an electrical insulator which polarizes when exposed to an external electric field. Instead of conducting free electrons like a metal, its bound charges shift to form microscopic dipoles, allowing the material to store electrical energy while minimizing current flow.
Dielectric monitoring – It is a means of tracking the cure of thermosets by changes in their electrical properties during material processing.
Dielectric object – It is an electrical insulator which does not conduct direct current. Instead of free electron flow, it responds to an external electric field through internal charge polarization, which stores and releases electrical energy.
Dielectric oven – It is also called dielectric heater. It is an industrial heating system which uses high-frequency radio waves or micro-waves to heat non-conducting materials internally. Rather than relying on external heat transfer, the electro-magnetic field creates rapid molecular oscillation, causing the material to heat up evenly throughout its entire volume.
Dielectric pressure – It typically refers to the electrostatic compressive or boundary stress exerted on or within a dielectric material because of an electric field (derived from the Maxwell stress tensor), or it describes the mechanical clamping force applied alongside high-frequency electric fields during dielectric / RF (radio frequency) welding.
Dielectric sample – It is a specific piece or sample of an insulating material prepared for testing its electrical, polarization, and energy-storage characteristics under an applied electric field.
Dielectric shield – In a cathodic protection system, it is an electrically non-conductive material, such as a coating, plastic sheet, or pipe, that is placed between an anode and an adjacent cathode for avoiding current wastage and for improving current distribution, normally on the cathode.
Dielectric sphere – It is a three-dimensional spherical object made of an insulating, polarizable material which stores and transmits electrical energy through internal dipole polarization rather than conducting free electrons. When placed in an external electric field, it uniformly polarizes and alters the surrounding electrostatic field.
Dielectric strength – It is the property of an insulating material which enables it to withstand electric stress. It is also the average potential per unit thickness at which failure of the dielectric material occurs.
Dielectric susceptibility – It is also called electric susceptibility. It is a dimensionless proportionality constant which measures how easily a material polarizes when exposed to an external electric field. It dictates how much internal dipole moment per unit volume a material creates to reduce the net electric field.
Dielectric window – It is an insulating barrier which allows electro-magnetic waves, RF (radio frequency) power, or micro-waves to pass through while hermetically sealing and separating different environments, such as a high-vacuum tube or plasma chamber from the outside atmosphere.
Dielectrometry – It is the use of electrical techniques to measure the changes in loss factor (dissipation) and in capacitance during cure of the resin in a laminate.
Die length – It is the physical length of the parallel, non-tapered section at the exit of a die. It is an important parameter in manufacturing processes like extrusion, wire drawing, and injection moulding since it dictates the final shape, dimensional stability, and surface quality of the part.
Die-less numerical control (NC) forming – It is also known as incremental sheet forming. It is a metal-working process that shapes sheet metal into 3D geometries using a computer-controlled deforming tool rather than a traditional, custom-built die. It creates parts via localized plastic deformation using small, progressive tool movements.
Die life – It refers to the total number of parts, cycles, or operational hours a manufacturing die can produce before it fails, degrades, or needs major repair. It is an important metric for production cost, part quality, and manufacturing efficiency. It is the productive life of a die impression, normally expressed as the number of units produced before the impression has worn beyond permitted tolerances.
Die line – It is a longitudinal depression or protrusion formed on the surface of drawn or extruded material. Die lines are present to some degree in all extrusions and are caused by a roughening of the die bearing. These are lines or markings on formed, drawn, or extruded metal parts caused by imperfections in the surface of the die.
Die lock – In sheet metal stamping, die lock is an undesirable geometric condition where the shape of a stamped part becomes mechanically trapped inside the die cavity. In manufacturing methods involving molten or liquid materials (e.g., plastic injection moulding, high-pressure die casting), die lock is a functional metric measured in force.
Die lubricant – It is a lubricant applied to the working surfaces of dies and punches for facilitating drawing, pressing, stamping, and / or ejection. In powder metallurgy, the die lubricant is sometimes mixed into the powder before pressing into a compact. It is also a compound which is sprayed, swabbed, or otherwise applied on die surfaces or the work-piece during the forging or forming process for reducing friction. Lubricant also facilitates release of the part from the dies and provide thermal insulation.
Die lubrication – It is the application of specialized fluids or solid coatings between a metal work-piece and a forming die to reduce friction, dissipate heat, and prevent defects. It establishes a protective barrier that enables clean part separation, prevents soldering (sticking), and extends tool life.
Die making – It is a specialized sub-discipline of tool engineering focused on the design, fabrication, and maintenance of custom dies. Dies are precision ‘reverse’ tools used to cut, bend, or shape materials, mainly sheet metal and plastics, into functional shapes at scale. Die-making needs an intersection of mechanical aptitude, material science, and precision machining. At its core, the practice revolves around tooling and replication, mechanical operations, and types of dies. The die-making workflow bridges the gap between theoretical computer-aided design (CAD) and physical production floor reality. The general practice includes design and planning, machining and fabrication, and assembly and tryout. Understanding the standards of die-making involves mastering precision metrology and metallurgy.
Die manufacturing – It is the process of designing and fabricating specialized, custom-engineered tools (dies) used in presses and machines to cut, shape, or form raw materials (mainly metals) into finished or semi-finished parts through mechanical force. Dies act as the customized interface between a machine and the material to ensure precision and mass-production consistency.
Die match – It is the condition where dies, after having been set up in a press or other equipment, are in proper alignment relative to each other.
Die material attributes – Die materials are to endure extreme forces, high temperatures, and continuous abrasive wear. Proper selection needs balancing three main mechanical properties, frequently called the ‘performance triangle’.
Die materials – These are specialized metals, alloys (like high-carbon or chrome steels), or hard compounds (like tungsten carbide) used to manufacture the moulds and tooling that shape, cut, or form raw materials. They are to withstand immense mechanical stress, thermal shock, and abrasive wear.
Diene – It is an organic compound containing two double bonds, normally between carbon atoms. It is a type of unsaturated hydrocarbon belonging to the alkene family. Dienes are fundamental building blocks in organic synthesis and the polymer industry, frequently used as monomers to create synthetic rubbers. Depending on how the double bonds are arranged in the molecule, dienes are categorized into three main types namely conjugated dienes, isolated dienes, and cumulated dienes.
Diene rubber – It is a synthetic elastomer built from monomers containing two carbon-carbon double bonds (dienes). The leftover double bonds allow the material to undergo vulcanization, creating cross-linked polymer networks which provide high elasticity, resilience, and tensile strength for engineering uses.
Die number – It is the number assigned to a die for identification and cataloging purposes, and which normally is assigned for the same purpose to the product produced from that die.
Die opening – In flash or upset welding, it is the distance between the electrodes, normally measured with the parts in contact before welding has commenced or immediately upon completion of the cycle but before upsetting. In powder metallurgy, it is the entrance to the die cavity.
Die-overloading – It occurs when the mechanical or thermal stress applied to a die exceeds the material’s yield strength or design limits. This typically leads to catastrophic tool failure, such as gross cracking, plastic deformation, or premature fatigue. Die-overloading is heavily tied to operational and design factors such as mechanical overloading, thermal overloading, and die design flaws.
Die pad – It is a movable plate or pad in a female die. It is normally used for part ejection by mechanical means, springs, or fluid cushions.
Die-preheating – It is the process of uniformly heating a metal-forming tool (die) to a specific temperature before beginning operations like die-casting, forging, or extrusion. It prevents the die from rapidly absorbing heat from the molten or hot metal, ensuring proper material flow and structural integrity.
Die pressing – It is a process which converts loose, granular raw material into a solid, high-density part. This is achieved by pouring the material into a rigid mould (the die) and applying heavy, frequently uniaxial, compressive force through a hydraulic or mechanical punch.
Die proof – It is a casting of a die impression made to confirm the accuracy of the impression.
Die pull – It is the direction in which the solidified casting is required to move when it is removed from the die. The die pull direction is to be selected such that all points on the surface of the casting move away from the die cavity surfaces.
Die radius – It is the radius on the exposed edge of a deep-drawing die, over which the sheet flows in forming drawn shells.
Die-reworking – It is also called die regeneration. It is the process of restoring worn or damaged metal dies to their original geometry and metallurgical properties. Instead of replacing expensive tooling, manufacturers use techniques like robotic welding, laser cladding, and precision machining to repair the die surface.
Dies and inserts – These are complementary, interchangeable tooling components used in manufacturing, machining, and heavy-duty mechanical operations. Normally, a die acts as a heavy-duty framework or mould, while an insert is the smaller, replaceable component which actually touches, grips, or shapes the material.
Dies and moulds – These are hardened tool-steel or carbide forms used for shaping metals. The main difference is their state of operation. Moulds shape metals in a liquid or molten state (casting), while dies shape or cut solid metals using mechanical force (stamping, forging, or extrusion).
Diescher discs – These are specialized, rotating, disc-shaped guiding devices used during the rotary tube piercing process. They are a hallmark feature of the Diescher mill, an industrial setup used to manufacture seamless steel tubes from solid round billets.
Diescher mill – It is a metal-working machine used mainly in the production of high-quality, seamless steel tubes. It operates as a rotary skew rolling mill which elongates thick-walled tube shells over an internal mandrel or plug while using large rotating discs to constrain and guide the metal. The process takes a solid, hot billet or a hollow shell and reduces its wall thickness while improving the overall concentricity and dimensional accuracy of the tube.
Diescher process – It is frequently associated with the Diescher tube rolling mill. It is a heavy industrial method used to manufacture seamless steel pipes and tubes. It replaces standard fixed guide shoes with rotating ‘Diescher discs’ to create highly stable, thin-walled tubes.
Diescher tube rolling mill – It is a specialized seamless steel pipe manufacturing machine. It uses two rotating cone-shaped rolls and a central plug to stretch-roll and elongate thick-walled hollow billets into long, precision-formed seamless tubes.
Diesel – It is a type of heavy petroleum fuel. It refers to a type of fuel derived from petroleum which is used in diesel engines and also contributes to greenhouse gas emissions, including methane, in the atmosphere.
Diesel engine – It uses diesel as the fuel. It is an internal combustion engine in which ignition of the fuel is caused by the high temperature of the air in the cylinder because of the mechanical compression (adiabatic compression).
Diesel engine model – It is a physical, mathematical, or computational representation of a compression-ignition internal combustion engine. It simulates thermodynamic cycles, fuel injection, and mechanical power output to analyze performance, design control systems, or predict transient behaviour.
Diesel exhaust – It is the complex mixture of gasses, vapours, liquid aerosols, and solid carbon soot produced when diesel fuel undergoes combustion inside a compression-ignition engine.
Diesel fuel – It is a fractional distillate of petroleum consisting of a complex blend of hydrocarbon chains (typically C10 to C24), specifically engineered for compression-ignition internal combustion engines where auto-ignition occurs through high-temperature compressed air rather than an external spark.
Diesel generator – It is an integrated electro-mechanical system which converts the chemical energy of diesel fuel into mechanical work through compression ignition, and subsequently transforms that mechanical energy into electrical power using a synchronous AC (alternating current) alternator.
Diesel generator set – It is a combined unit of a diesel engine and an electric generator (alternator) which work together to produce electrical energy. Diesel generator sets are mainly used as back-up power during outages or as main power in off-grid locations.
Diesel locomotive – it is a self-propelled rail vehicle powered by an internal combustion diesel engine which uses a mechanical, hydraulic, or electrical transmission system to drive its wheels. Most major mainline units are diesel-electric, functioning as mobile power plants where the diesel engine turns a generator to supply power to electric traction motors on the axles.
Diesel oil, light – Light diesel oil (LDO) is having flash point above 66 deg C. It is a blend of distillate components and a small quantity of residual components. It is used as a fuel in certain boilers and furnaces.
Diesel oil, high speed – High speed diesel (HSD) oil is a complex mixture of hydro carbons. It is a brown-coloured oily liquid with pungent smell. It has a pungent smell. It is used in diesel engines of mobile equipment, diesel-generator sets, and locomotives. It is the prime mover in a wide range of power generation and pumping applications.
Diesel oxidation catalyst – It is a flow-through exhaust aftertreatment device which uses chemical oxidation to convert toxic carbon mono-oxide and unburned hydro-carbons into harmless carbon di-oxide and water vapour. It acts as the first line of defense in modern diesel emission control systems.
Diesel particulate filter – It is an exhaust after-treatment device engineered to capture and remove diesel particulate matter (soot and ash) from internal combustion engine exhaust gases, achieving filtration efficiencies above 90 % through a porous ceramic honeycomb wall-flow structure.
Diesel particulate matter – It is a complex mixture of microscopic solid soot cores and liquid droplets found in diesel exhaust. It is classified as a dangerous emission pollutant composed of elemental carbon, adsorbed organic hydro-carbons, ash, and metallic traces which need active filtration and regeneration systems.
Die separation – It is the space between the two halves of a die casting die at the parting surface when the dies are closed. The separation can be the result of the internal cavity pressure exceeding the locking force of the machine or warpage of the die because of the thermal gradients in the die steel.
Die set – It is a guided mechanical assembly used in presses to hold, align, and support customized tools like punches and dies. It ensures precise, repeatable motion during metal forming. The die set acts as the foundation for the operation. Depending on the specific metallurgical process, die sets perform different critical functions.
Dies for open-die forging – These are simple, flat, V-shaped, or customized contoured tools used to compress hot metal billets. Unlike closed (impression) dies, these do not enclose the work-piece. This ‘open’ design allows metal to flow freely on the unconstrained sides as it is hammered or pressed.
Die shape -It refers to the custom-machined geometry of a die, a precision-engineered tool used to cut, form, or shape materials. The shape can be cutting (like a cookie cutter) or forming (like a press which stamps or extrudes). It comprises a punch (male component) and a cavity (female component).
Die shift – It is the condition which occurs after the dies have been set up in a forging unit in which a portion of the impression of one die is not in perfect alignment with the corresponding portion of the other die. This results in a mismatch in the forging, a condition which is to be held within the specified tolerance.
Die shoes – These are the upper and lower plates or castings which constitute a die set (punch and die holder). It is also a plate or block upon which a die holder is mounted, functioning mainly as a base for the complete die assembly. This plate or block is bolted or clamped to the bolster plate or the face of the press slide.
Die shop tools – These refer to specialized, custom-built devices used in manufacturing to cut, shape, or form materials under high pressure. They are the backbone of mass production, ensuring that parts like metal stampings, plastic moulds, and castings are made identically and with strict precision.
Die sinker – it is a specialized tool which erodes conductive materials using electric sparks. It creates precise cavities and intricate moulds by plunging a shaped electrode into a work-piece, which is fully submerged in a dielectric fluid.
Die sinking – It is a non-contact machining process which uses controlled electrical discharges (sparks) to erode conductive materials. It utilizes a specifically shaped electrode (normally copper or graphite) as a ‘negative’ stamp to create precise cavities, blind contours, and intricate internal geometries in hard metals. It is the machining of the die impressions for producing forgings of the needed shapes and dimensions.
Die sinking technique – It is a precision machining technique used to carve intricate, negative-impression cavities into solid metal blocks. These shaped metal blocks act as moulds or ‘dies’ for industrial processes like plastic injection moulding, die-casting, and metal forging. The most prevalent and advanced die sinking technique is die-sinking EDM (electrical discharge machining), also referred to as sinker, ram, or cavity-type electrical discharge machining.
Die size – It typically refers to the physical dimensions of the customized tool or mould cavity used to cut, shape, or compress raw materials like molten metal or sheet metal. It directly dictates the final size, geometry, and tolerances of the produced metal component.
Die space – It is the maximum space (volume), or any part of the maximum space, within a press for mounting a die.
Die specifications – These specifications define the exact physical and mechanical parameters of a specialized manufacturing tool (die). They include die materials selection, die design, and die manufacture. They dictate how the tool is to be built and operated to cut, shape, or mould materials. These guidelines ensure the die, such as those used in metal stamping, plastic extrusion, or die casting, functions flawlessly within a production press. Die specifications detail several crucial elements of the tooling.
Die spindles – These are also called roll die spindles. These are heavy-duty, rotating shafts in thread rolling machines which hold cylindrical or flat-formed metal dies. By rotating under immense pressure against a metal blank, they cold-form threads, knurls, or helical grooves without removing material.
Dies, rolls – Circular dies are normally ground after hardening. A2 tool steel is preferred for short production runs on all except the materials most difficult to thread, since its grindability is good and its wear resistance is adequate. More expensive steels are justified for long runs and for work materials which are difficult to roll.
Die stamping – It is the general term for a sheet metal part which is formed, shaped, or cut by a die in a press in one or more operations.
Die steels – These are steels which are used in die forging for making dies which work under heavy pressure and which produce a flow of metal compressing it into the desired form or shape. These steels are used for making crimping dies, embossing dies, heading dies, extrusion dies, and staking dies etc. These steels are properly heat treated to get the desired properties.
Di-ester – It is an organic compound which contains two ester functional groups. They are typically formed by the reaction of a di-carboxylic acid with two molecules of a mono-hydric alcohol. Because of their excellent thermal stability and lubricity, di-esters are widely used as synthetic base stocks in high-performance lubricants and industrial fluids.
Die stress analysis – It is the evaluation of forces, strains, and thermal loads acting on a manufacturing die. Used mainly in metal forming, casting, and extrusion, it predicts how dies are going to perform under intense pressure and temperature to prevent early tool failure or cracking. In manufacturing and design, this analysis focuses on balancing die durability with production efficiency.
Die structure – It refers to the physical layout and mechanical assembly of the die components. A typical die set consists of a punch (the moving top half) and a die block (the stationary bottom half) enclosed within a rigid structure of guide pins and plates that ensure high precision.
Die surface temperature – It is the thermal condition of a physical mould or forming tool (the die) where it directly contacts the material being shaped. In manufacturing processes like die casting and hot forging, controlling this boundary temperature dictates the cooling rate of the molten or hot metal. Maintaining the optimal die surface temperature is important for preventing surface defects (like shrinkage or soldering in castings), managing thermal expansion, and extending die life. Extreme temperatures, frequently reaching 600 deg C to 900 deg C during hot forging, lead to severe mechanical and chemical loads, making temperature on the die surface important for modeling industrial processes. Since contact surfaces experience thermal spikes and rapid dips during each production cycle, factors like coolant flow rates, lubricants, and cycling times are continuously adjusted to keep it within safe operating bounds.
Die swell – It is the expansion of the polymer melt which occurs as the extruded melt exits the die. This is because of the aligned polymer chain.
Die system – It is a specialized, purpose-built assembly of tooling components used in manufacturing to cut, form, or replicate materials through applied mechanical force, pressure, or casting.
Die taper angle – It refers to the specific angle machined or engineered into a mould, cutting tool, or forming die. This gradual, uniform change in cross-section ensures proper part guidance, minimizes friction during material flow, and allows for the seamless ejection or release of finished products.
Die temperature – It refers to the temperature of the mould, tooling, or die used to shape metals (such as in die casting, extrusion, or forging). It is an important parameter which directly influences metal flow, part quality, and overall die life-span.
Di-ethylene glycol amine – It is also called di-glycol-amine. It is a versatile primary amine. Its chemical formula is C4H11NO2 and it is widely used as a solvent, chemical intermediate, and acid gas absorbent.
Di-ethylene glycol amine (DGA) is normally referred to by the chemical name 2-(2-aminoethoxy)ethanol. It is a clear, colourless or pale-yellow liquid with a mild, distinct amine odour.
Di-ethylene glycol – It is an organic compound with the formula (HOCH2CH2)2O. It is a colourless, practically odourless, and hygroscopic liquid with a sweetish taste. It is a four-carbon dimer of ethylene glycol. It is miscible in water, alcohol, ether, acetone, and ethylene glycol. Di-ethylene glycol (DEG is a widely used solvent.
Di-ethylene-tri-amine penta-acetic acid – It is also known as pentetic acid. It is a synthetic amino-poly-carboxylic acid and high-capacity chelating agent. It features a di-ethylene-triamine backbone attached to five carboxy-methyl groups. It is used to bind and sequester free metal ions (like iron, copper, and zinc) to control chemical reactions, prevent scaling, and stabilize per-oxide bleaching.
Die wear – It is the progressive degradation, material loss, or dimensional alteration of a forming tool (die) caused by intense friction, heat, and pressure during processes like metal stamping, extrusion, or forging. It directly impacts part tolerances, surface finish, and tool life.
Die wear tolerance – It is the dimensional allowance given to a manufactured metal component to compensate for the gradual degradation of the forging or casting die. As dies endure extreme pressure, heat, and friction, their cavities expand or erode, causing the final parts to slowly drift from their minimum to maximum specified size.
Dietert process – It is a patented foundry method used to produce precision moulds. It involves blowing a contoured sand core around a pattern to create half of a mould, allowing for the efficient, high-volume production of intricate and highly accurate metal castings.
Dietert tester – It is a patented instrument used for direct hardness readings. It works by pressing a pin into a metal part and measuring the impression depth to give an instant Brinell hardness number (BHN) without needing magnification or conversion tables.
Diethanolamine – It is a chemical compound classified as a secondary amine and diol. It is a colourless liquid with a slight ammonia-like odour, frequently used as a surfactant, emulsifier, and in the manufacturing of several chemicals.
Die welding – It is also known as forge welding and cold welding. It is a solid-state welding in which metals are heated in a forge (in air) and then welded together by applying pressure or blows sufficient to cause permanent deformation at the interface.
Difference approximation – It is a numerical method used to estimate the derivative of a continuous function or solve differential equations by replacing calculus operators with discrete arithmetic values over a sampled grid. It relies on a small finite step size rather than an infinitesimal limit.
Difference image – It is a derived image showing the absolute mathematical difference between corresponding pixel values of two baseline images. Brighter or non-zero pixels highlight changes, motion, or structural flaws while static areas turn black.
Difference signal – It is a signal which represents the numerical or electrical variance between two separate input signals (V1 – V2). It is widely used in differential signalling and instrumentation amplifiers to isolate true data while cancelling out external noise.
Differential –A differential is a gear train with three shafts which has the property that the rotational speed of one shaft is the average of the speeds of the others, or a fixed multiple of that average.
Differential aeration – It refers to an electrochemical corrosion process which occurs when different areas of the same metal surface contact zones with unequal oxygen concentrations. The oxygen-starved area becomes the anode and corrodes, while the oxygen-rich area acts as the cathode. It is the corrosion which occurs when a material is in contact with two environments of differing oxidant content, leading to variations in oxygen concentration.
Differential aeration cell – It is an electrolytic cell, the electro-magnetic force of which is because of a difference in air (oxygen) concentration at one electrode as compared with that at another electrode of the same material.
Differential amplifier – It is an electronic circuit which amplifies the voltage difference between two input signals while blocking any signals common to both inputs. It serves as a core building block in analog systems and operational amplifiers.
Differential analysis – It is a mathematical approach which applies the governing principles of physics, such as the conservation of mass, momentum, and energy, to infinitesimal fluid or structural elements, resulting in partial differential equations (PDEs) used to model dynamic systems.
Differential annealing – It is the localized heating of part of a blank so that only specific areas are annealed.
Differential arm length – It normally refers to the difference in path or physical length (dL = L1 – L2) between two corresponding paths or mechanical lever arms in a symmetrical system, such as an optical interferometer, a balance scale, or a differential linkage mechanism.
Differential coating – It is a coated product having a specified coating on one surface and a significantly lighter coating on the other surface such as a hot dip galvanized product or electrolytic tin plate.
Differential contraction – It is also referred to as differential shrinkage. It occurs when different sections of a metal part cool and shrink at unequal rates. It is caused by non-uniform temperature distributions or dissimilar metallurgical structures, frequently resulting in severe internal residual stresses, part distortion, or cracking. Understanding exactly where and how this phenomenon occurs helps metallurgists control component integrity and prevent material failure. In manufacturing and composites, differential contraction refers to the phenomenon where two or more joined materials cool and shrink at different rates. Since each material has a unique coefficient of thermal expansion (CTE), temperature drops cause internal stress, warping, or delamination between layers. In plate tectonics, differential contraction describes the uneven volume reduction of subducted lithosphere layers. As a tectonic slab descends into the earth’s mantle, different mineral phases compress and shrink at varying rates, generating intense down-dip stresses. These residual stresses explain deep-focus earthquakes which occur in the subducting slab.
Differential control valve – It is also called differential pressure control valve (DPCV). It is a self-acting mechanical or electronic regulator which maintains a constant pressure difference (dP) between two specific points in a fluid system, independent of supply pressure changes.
Differential costs – Differential costs are the difference in total cost which arise from the selection of one alternative to the other.
Differential curve – It is a segmented section of a curved conveyor featuring multiple side-by-side roller rows, requiring regular checks for smooth material flow.
Differential delay – It is the time difference between the fastest and slowest signals or paths when data travels across multiple parallel channels, cables, or network routes.
Differential entropy – It is the continuous analog of Shannon entropy. It measures the uncertainty or randomness of a continuous random variable with a probability density function ‘p(x)’, defined as ‘h(X) = – integral p(x)log p(x) dx’.
Differential equation – It is a mathematical equation which relates an unknown function to its derivatives. In these equations, the function represents a physical quantity, and the derivative represents its rate of change. A differential equation expresses a relationship between the changing quantity and the change in another quantity.
Differential equation of heat conductivity – It mathematically models how temperature distributes through a material over time. Derived from the first law of thermodynamics (energy conservation) and Fourier’s law of heat conduction, it links temperature changes to a material’s thermal properties.
Differential floatation – It means separating a complex ore into two or more valuable minerals and gangue by flotation. It is also called selective flotation.
Differential frequency – It refers to the resultant beat or intermediate frequency (df = |f1 – f2|) produced by mixing two signals, or the incremental change in frequency used in precision sensors and modulation systems.
Differential gain – It is the amplification factor an electronic circuit applies to the difference between two input voltages while rejecting any signals common to both inputs.
Differential heating – It is the heating which intentionally produces a temperature gradient within an object such that, after cooling, a desired stress distribution or variation in properties is present within the object.
Differential heat treatment – It is a process which alters the physical and mechanical properties of different sections of a single metal object. It yields zones with varying hardness, toughness, or flexibility, such as a hardened cutting edge and a softer, shock-absorbing spine on a blade.
Differential inclusion – It is a mathematical condition where the derivative of a state vector is constrained to lie within a set-valued function, reflecting uncertainties in dynamic system modeling. It represents scenarios where control variables are subject to restrictions, leading to a range of possible outcomes for the system’s evolution.
Differential input – It is a circuit configuration which measures the voltage difference between two complementary signal terminals (V+ and V-) rather than measuring a single voltage relative to a common ground. This technique blocks shared noise and handles floating voltage references safely.
Differential interference contrast illumination – It is a microscopic technique using a beam-splitting double-quartz prism, i.e., a modified Wollaston prism placed ahead of the objective together with a polarizer and analyzer in the 90-degree crossed positions. The two light beams are made to coincide at the focal plane of the objective, revealing height differences as variations in colour. The prism can be moved, shifting the interference image through the range of Newtonian colours.
Differentially flat system – It is a type of dynamical control system where all internal states and control inputs can be completely written as algebraic functions of a special set of output, called flat outputs, and a finite number of their time derivatives, without needing to integrate any differential equations.
Differential manometer – It is a fluid-measurement device used to find the pressure difference between two specific points, either in the same pipe or in two separate pipes. Unlike a standard gauge which measures pressure relative to the atmosphere, it compares two process pressures directly.
Differential measurement – It determines the difference in a physical property or signal between two separate points rather than measuring an absolute value relative to a fixed ground or reference. This technique cancels out common-mode noise and external interference to provide high precision.
Differential mobility analyzer – It is an instrument which classifies charged submicron particles or nano-particles suspended in a gas stream according to their electrical mobility in an electric field. It acts as a precise narrow band-pass filter for size-based particle separation.
Differential mode – It describes signals or currents which flow in opposite directions through a pair of conductors (one wire goes forward, the other returns). It is the standard method for transmitting intended, useful data or power.
Differential output – It is a circuit or device configuration that transmits a signal using two complementary lines. The final signal value is defined strictly by the voltage difference between the two outputs (V+ – V-), rather than a single line measured against a common ground.
Differential pair – It is a pair of complementary conductors, such as copper traces on a PCB (printed circuit board) or twisted wires, which carry equal and opposite signals to transmit data reliably. The receiving end measures the voltage difference between the two lines rather than a single signal versus ground, which cancels out external noise and reduces electromagnetic interference.
Differential phase – It has two main definitions depending on the sub-field: in analog video systems, it is the unwanted change in colour hue caused by shifts in image brightness. In digital communications, it forms the basis of differential phase shift keying (DPSK), where data is encoded through relative phase changes between successive signal waves rather than an absolute reference.
Differential phase shift – It typically refers to differential phase shift keying (DPSK), a digital modulation method. It encodes binary data by changing the phase of a carrier wave relative to the previous symbol rather than using a fixed reference phase.
Differential pressure – It is the pressure measured with respect to another pressure and is expressed as the difference between the two values. This represents two points in a pressure or flow system and is referred to as the ‘dp’.
Differential pressure control – It is the measurement and regulation of the pressure drop (dP = P1 – P2) between two distinct points in a fluid or gas system. It uses feedback loops, transmitters, and automated valves to keep this difference stable. This optimizes flow rates, prevents equipment damage, and manages cleanroom air purity.
Differential pressure switch – It is an electro-mechanical or electronic device which senses the pressure difference between two distinct system ports and triggers an electrical contact when that value crosses a preset threshold.
Differential pressure transducer – It is a sensing device which measures the difference (dP) between two distinct pressure points (P1 and P2) in a system and converts that physical value into a proportional electrical output signal.
Differential pressure transmitter – It is an instrument which can consistently and accurately create a pressure drop in a pipe and then use the pressure measurement on either side to provide the rate of flow within the pipe. Differential pressure transmitters are comprised of a robust electronic module and two sensory diaphragms which provide the electronic reading of applied forces in a containment vessel. These arrangements are physically connected in set configurations depending upon the application requirements.
Differential process – It very frequently refers to a physical or chemical operation where changes occur in small, gradual increments (such as differential vapourization in reservoir engineering), or it relates to mechanical / fluid systems using a differential mechanism or pressure drop (dP).
Differential processing – It normally refers to methods which analyze, transmit, or compute data based on differences between signals, values, or states rather than absolute levels. This approach improves noise immunity, reduces data redundancy, and accommodates varying physical constraints.
Differential pulley – It is also called chain hoist. It is used to manually lift very heavy objects. It is operated by pulling upon the slack section of a continuous chain which wraps around two pulleys on a common shaft. The two pulleys are joined together such that they rotate as a unit on the single shaft that they share. The relative sizing of the two connected pulleys determines the maximum weight which can be lifted by hand. If the pulley radii are close enough, then the load remains in place (and not lower under the force of gravity) until the chain is pulled.
Differential quadrature element method – It is an advanced numerical analysis technique which combines the high-order accuracy of the differential quadrature method (DQM) with the domain-decomposition flexibility of the finite element method (FEM). It solves complex engineering differential equations by splitting a system into discrete elements.
Differential quadrature method – It is a fast numerical technique used to solve differential equations. It approximates a function’s derivative at a specific point as a weighted linear sum of all functional values along a grid line, turning complex differential equations into simple algebraic equations.
Differential quenching – It is the selective quenching of the different parts of the same steel object.
Differential refractometer – It is an analytical instrument used in chemical and polymer engineering to measure the minute difference in refractive index (dn) between a solution (a solute dissolved in a solvent) and the pure solvent alone.
Differential scanning calorimetry – It is a thermo-analytical technique in which the difference in the amount of heat required to increase the temperature of a sample and reference is measured as a function of temperature. Both the sample and reference are maintained at nearly the same temperature throughout the experiment.
Differential scanning calorimetry (DSC) curve – It is a graphical plot generated during thermal analysis. It typically displays heat flow (the energy absorbed or released by a sample) on the vertical axis against temperature or time on the horizontal axis. A typical differential scanning calorimetry (DSC) curve reveals how a material behaves when subjected to a controlled heating, cooling, or isothermal programme. It highlights specific physical and chemical changes by showing deviations (peaks or shifts) from a flat baseline.
Differential settlement – It is the unequal downward movement of different parts of a structure’s foundation. It happens when one section sinks faster or deeper than another. This uneven shift creates high stress and twists the building.
Differential signalling – It transmits information through two complementary voltage lines to cancel noise, while an instrumentation amplifier is a closed-loop gain block featuring high input impedance designed to precisely measure and scale small differential voltages without loading the source.
Differential sticking – It is a drilling problem where the drill string becomes immobile against a well-bore wall. It happens when high hydrostatic mud pressure pushes the pipe into a thick filter cake inside a permeable formation where the well pressure exceeds the reservoir pressure.
Differential temperature analysis – It is a technique used to measure temperature differences between a sample and a reference material as they are subjected to controlled heating or cooling, frequently utilized in the characterization of materials.
Differential temperature controller – It is an electronic device which measures the temperature at two distinct locations using separate sensors, compares the difference (dT), and switches a relay or active component (like a pump or valve) when that variance reaches a pre-set threshold.
Differential thermal analysis – It is a technique in which the difference in temperature between the sample and a reference material is monitored against time or temperature while the temperature of the sample, in a specified atmosphere, is programmed. It is a thermo-analytic technique which is similar to differential scanning calorimetry. In this analysis technique, the material under study and an inert reference are made to undergo identical thermal cycles, while recording any temperature difference between sample and reference.
Differentiating circuit – It is an electronic setup which gives an output signal based on how fast the input signal changes over time. Its output matches the mathematical time derivative of the input.
Differentiating factor – It is also capped derivative operation. It refers to a mathematical rate of change, an electronic circuit which yields an output proportional to a signal’s rate of change, or a design / product distinction feature which sets a technical solution apart from alternatives.
Differentiation process – It is finding how fast a function changes. It is the core process used to find the derivative of a function, which measures the instantaneous rate of change of one variable relative to another. Geometrically, it calculates the exact slope or gradient of a curve at any given point.
Differentiator – It is a hardware circuit or system which gives an output signal matching the time derivative (the rate of change) of its input signal. It turns rapid changes in voltage into sharp spikes or pulses.
Difficult-to-extrude alloys – These are materials with high deformation resistance or a narrow hot-working temperature range, making them challenging to push through an extrusion die without causing structural defects or die failure. These alloys need immense pressure and precise, frequently slower, extrusion speeds to maintain the integrity of their cross-sectional profiles.
Diffracted beam – It is a redirected beam of radiation or particles (such as X-rays, electrons, or neutrons) which changes course after interacting with a periodic structure, such as the atomic planes of a crystal lattice, adhering to Bragg’s law.
Diffracted intensity – It is the measured strength or amplitude of a wave (such as X-rays, electrons, or neutrons) scattered at specific angles when meeting constructive interference conditions in a crystal lattice. It is directly proportional to the square of the structure factor of those specific atomic planes.
Diffraction – It is a modification which the radiation undergoes, e.g., in passing by the edge of opaque bodies or through narrow slits, in which the rays appear to be deflected. It is also the coherent scattering of X-rays by the atoms of a crystal which necessarily results in beams in characteristic directions, which is sometimes termed reflection. Diffraction is also the scattering of electrons by any crystalline material through discrete angles depending only on the lattice spacings of the material and the velocity of the electrons.
Diffraction angle – It is the specific angle at which a wave (such as light, sound, or X-rays) bends or spreads out after encountering an obstacle or passing through an aperture. It describes the trajectory of the newly formed wave-fronts resulting from wave interference. The specific value of the diffraction angle depends on the wave-length of the incident wave and the physical dimensions of the barrier or slit.
Diffraction condition – It refers to the criteria under which constructive interference occurs between waves elastically scattered by the atomic patterns of a crystal lattice, typically expressed through the Laue condition or Bragg’s law. These conditions are linked to the arrangement of atoms within the unit cell and the associated interplanar distances.
Diffraction contrast – In electron microscopy, it is the contrast produced by intensity differences in Bragg-diffracted beams from a crystalline material. These differences are caused by regions of varying crystal orientation.
Diffraction effect – It is the bending and spreading of waves, such as light, sound, radio, or water waves, when they encounter an obstacle, edge, or aperture whose size is close to the wave’s wave-length. This causes waves to enter shadowed zones.
Diffraction grating – It is an artificially produced periodic array of scattering centres capable of producing a pattern of diffracted energy, such as accurately ruled lines on a plane surface.
Diffraction line – It refers to the visual or recorded peak (line) in an X-ray diffraction (XRD) pattern, where incoming radiation constructively interferes after reflecting off a metal’s internal atomic planes. These lines or peaks act as a distinct fingerprint of the material, and their characteristics indicate critical metallurgical properties.
Diffraction limit – It is the fundamental physical restriction on the spatial resolution of an optical system, caused by the wave nature of light. It dictates that light passing through a finite aperture cannot be focused into an infinitely small point, but instead forms a blurred diffraction pattern (Airy disk), capping the smallest resolvable detail.
Diffraction pattern (X-rays) – It is the spatial arrangement and relative intensities of diffracted beams.
Diffraction plane – It refers to any set of parallel, equally spaced atomic planes (lattice planes) within a crystal structure which can elastically scatter incident waves, such as X-rays, electrons, or neutrons, to produce constructive interference.
Diffraction problem – It is the analytical or numerical challenge of finding how waves (electro-magnetic, acoustic, or elastic) bend, spread, and scatter when they encounter obstacles, edges, or apertures whose sizes are comparable to the wave’s wavelength.
Diffraction ring – It is the diffraction pattern produced by a given set of planes from randomly oriented crystalline material.
Diffraction tomography – It is an advanced computational imaging and inverse scattering method used to reconstruct the three-dimensional internal structure or refractive index of an object. It illuminates a target with probing waves (such as light, sound, or X-rays) and measures the resulting scattered wave field from multiple angles. Unlike traditional ray-based computed tomography (CT) which assumes waves travel in straight lines, diffraction tomography accounts for the physical wave nature of radiation, specifically diffraction and refraction, using principles like the Fourier diffraction theorem.
Diffraction, X-ray – X-ray diffraction is a non-destructive analytical technique used to determine a material’s crystal structure and phase composition. By directing X-rays at a material, the regular arrangement of atoms causes the waves to scatter and interfere constructively, producing a unique diffraction ‘finger- print’.
Diffractogram – It is a visual plot or digital chart generated by X-Ray diffraction (XRD). It displays the intensity of scattered X-rays against the diffraction angle (2 theta). This graphical ‘finger-print’ reveals the precise atomic arrangements, phases, and internal stress states of metal alloys.
Diffractometer – It is an analytical instrument used to study the atomic and crystalline structure of materials by measuring the angles at which radiation (like X-rays, neutrons, or electrons) is diffracted. It is an instrument used to perform structural characterization of various samples, enabling the analytical study of crystal lattices through the constructive interference of monochromatic X-rays and crystalline samples. In metallurgy, an X-ray diffractometer (XRD) is a main tool for identifying phases, measuring residual stress, and characterizing crystalline textures.
Diffractometry – It is defined as an analytical technique which utilizes X-ray diffraction to determine the crystalline structure of materials, enabling the identification of crystalline phases, quantification of phase abundance, and analysis of physical properties in different inorganic and mineral compounds.
Differential equation – It is a mathematical equation which links an unknown function to its derivatives, representing the rate of change of a physical quantity. Instead of finding a single number, solving it means finding the actual function that describes how a system changes over time or space.
Diffuse double layer – It refers to the electrical double layer formed at the interface between charged colloidal particles and the surrounding medium, consisting of a fixed layer of counter ions (Stern layer) and a surrounding diffuse layer of mobile ions. This structure is important for maintaining electroneutrality in colloidal systems and influences the stability of colloidal suspensions.
Diffuse emission – It refers to pollution infiltrating the atmosphere from a large non-point source, for example, dust from a slag heap.
Diffuse field – It is a sound field where wave energy flows uniformly in all directions with equal probability and consistent energy density throughout the space. This statistical state occurs in highly reverberant rooms after several boundary reflections, making the sound pressure equal at any point.
Diffuse horizontal irradiance – It is the power of solar radiation scattered by the atmosphere, clouds, and particles falling on a flat, horizontal surface. It excludes direct, unscattered sunlight. Engineers use diffuse horizontal irradiance (DHI) in solar energy modelling, PV (photo-voltaic) system design, and building heat-gain calculations.
Diffuse irradiance – It is normally measured as diffuse horizontal irradiance (DHI). It is the solar radiation power per unit area which reaches the earth’s surface after being scattered by clouds, air molecules, dust, and water vapour in the atmosphere. Unlike direct beam radiation, it arrives from all directions across the sky dome.
Diffuse irradiation – It refers to the portion of global irradiation which is scattered in different directions because of the atmospheric interactions, as opposed to direct irradiation, which follows a constant direction.
Diffuse layer – It is the outer, mobile region of an electrical double layer where counter-ions spread out near a charged surface. Ion distribution here balances electrostatic attraction and thermal motion, governed by the Debye length.
Diffuse light – It is the light which scatters in several directions after hitting a rough surface or passing through a translucent material. This creates soft, uniform illumination with minimal glare and very faint shadows.
Diffuse necking – It is the non-uniform strain distribution along the length of a member loaded in tension which develops at the maximum load. The term ‘diffuse’ is used since the neck develops slowly, with little change in load, but an increase in axial strain near the load maximum.
Diffuser – It is a mechanical device designed to slow down the velocity of a fluid (liquid or gas) and increase its static pressure. This process, frequently called pressure recovery, is achieved by gradually expanding the cross-sectional area of the flow channel.
Diffuse radiation – It is solar energy which reaches the earth’s surface after being scattered by atmospheric particles, clouds, and pollutants, rather than traveling in a direct beam from the sun. It arrives from all angles in the sky, providing uniform light and heat.
Diffuser channel – It is a specially shaped flow passage which slows down a fluid’s velocity to recover high static pressure. It converts kinetic energy into potential pressure energy inside systems like centrifugal compressors, pumps, and gas ducts.
Diffuser efficiency – It is the ratio of the actual enthalpy change (or actual static pressure rise) to the ideal, isentropic enthalpy change as a fluid slows down to convert kinetic energy into static pressure.
Diffuse reflectance – It is the process where light or electro-magnetic radiation striking a rough, porous, or granular surface is scattered in several random directions instead of a single mirror-like angle. It forms the basis of non-destructive material testing, optical sensing, and computer graphics.
Diffuse reflection – It takes place when light or other waves hit a rough surface and scatter in several different directions instead of just one clean angle. This stops people from seeing a clear mirror image and creates soft, even light.
Diffuse reflector – It is a surface which scatters incident light, acoustic waves, or electro-magnetic radiation in multiple directions. This creates uniform brightness or luminance across a hemisphere regardless of the viewing angle, unlike a mirror-like specular reflector.
Diffuse target – It is an extended object or surface which scatters incident energy, such as light, radar waves, or sound, uniformly in all directions rather than reflecting it at a single specular angle. These targets are defined by a back-scatter or reflectance coefficient rather than a distinct point echo.
Diffuse transmittance – It is the transmittance value obtained when the measured radiant energy has experienced appreciable scattering in passing from the source to the receiver.
Diffusible flow – It typically refers to diffusional flow. It is the mass transport of atoms, ions, or molecules driven by a chemical potential or concentration gradient. It also describes turbulent diffusion, where mixing and transport occur across fluid layers.
Diffusible hydrogen – It is the mobile, non-trapped atomic hydrogen present within a metal (such as steel) at room or ambient temperatures which can move freely through the crystal lattice and escape or cause structural damage.
Diffusion – It means spreading of a constituent in a gas, liquid, or solid, tending for making the composition of all parts uniform. It is also the spontaneous movement of atoms or molecules to new sites within a material.
Diffusion aid – It is a solid filler metal sometimes used in diffusion welding.
Diffusional creep – It is a deformation mechanism where the normal stress on grain boundaries alters the energetic state of vacancies, leading to a diffusional flux that causes grain deformation, primarily occurring through either the grain interior (Nabarro–Herring creep) or grain boundaries (Coble creep), depending on conditions such as temperature.
Diffusional flow – It describes the net movement of mass, atoms, or momentum driven by a gradient, such as concentration, chemical potential, or velocity, rather than by bulk mechanical pressure. It governs phenomena from atomic creep in high-temperature metals to molecular mixing in fluid systems.
Diffusion-alloyed powder – It is a specialized powder metallurgy (PM) raw material where fine alloying elements (such as nickel, copper, and molybdenum) are thermally bonded to the surface of a base iron or steel powder core.
Diffusion-alloyed powder metallurgy steels – These steels are made from the diffusion of alloying elements such as nickel, copper and molybdenum, into the base steel powder during the sintering process. Graphite powder is admixed with the diffusion alloyed powder to provide the necessary level of carbon in the finished material.
Diffusion alloyed steel powder metal parts – These parts are created by thermally bonding the alloying elements to the individual particles of the base iron or steel. Similar to nickel and pre-alloyed steel grades, diffusion-alloyed steels are useful in medium to high-density applications and can achieve densities above 7 grams per cubic centimeter. Diffusion-alloyed steels are used in high strength applications and can be heat-treated to increase wear resistance. This process, known as diffusion alloying, results in a seamless integration of alloying components throughout the material.
Diffusional flow – It is the movement of atoms or ions within a material, which is particularly substantial in ceramics with small grains and at high temperatures under low loads. This process is influenced by factors such as grain size and the presence of precipitates at grain boundaries.
Diffusional flow mechanisms – These mechanisms refer to the mass transport of atoms or ions through a solid material from regions of high chemical potential to low chemical potential. This thermally activated movement drives phase transformations, homogenization, and high-temperature deformation. The two main atomic-level diffusion mechanisms which facilitate this flow are vacancy diffusion and interstitial diffusion.
Diffusion and adhesion – Adhesion is the attractive force holding two dissimilar materials together at their interface, while diffusion is one specific mechanism of adhesion where mobile molecules or polymer chains interpenetrate across that boundary to form a blended, continuous joint.
Diffusion annealing – The purpose of diffusion annealing is to eliminate dendritic segregation, eliminate regional segregation, homogenize the chemical composition, and modify columnar grains which appear during the crystallization of steels. During the process of diffusion annealing, the iron and carbide are diffused together. This process needs higher temperature, so the steel is heated above the upper critical temperature. Diffusion annealing is normally carried out at a temperature of 1,100 deg C to 1,300 deg C and then the steel is held at this temperature for 10 hours to 20 hours, followed by cooling.
Diffusion approximation – It is a mathematical method that simplifies complex particle, photon, or energy transport equations into a standard, second-order differential diffusion equation. It assumes that scattering events vastly outnumber absorption events, making directional flow look like random diffusion.
Diffusion barrier – It is a thin metallic or ceramic layer placed between two other materials to prevent them from chemically reacting, degrading, or inter-diffusing at high temperatures.
Diffusion-based model – It normally refers to either physical atomic diffusion models (how atoms move in metals to change microstructure) or AI (artificial intelligence) generative diffusion models (machine learning algorithms used for materials discovery).
Diffusion behaviour – It is the spontaneous net movement of mass, atoms, ions, or molecules from a region of higher concentration to a region of lower concentration, driven by a gradient in chemical potential or thermal energy.
Diffusion bond – Two matai pieces whether similar or dissimilar metals diffusion bond when their highly polished surfaces are pressed together under high pressure at high temperatures (typically 50 % to 80 % of the absolute melting point). The bonding process causes atoms to diffuse across the joint, creating a metallurgical bond without melting.
Diffusion bonded sinter – It is a solid-state product created by heating compressed metal powders or stacked metal parts below their melting points. Under heat and pressure, atoms migrate across particle boundaries, fusing them together into a dense, solid mass without ever melting into a liquid.
Diffusion bonded sintering – It is a solid-state joining technique where components or metal powders are fused together through intense heat and pressure. This bonding occurs at the atomic level without melting the base materials. This process creates strong, homogeneous bonds and unified structures.
Diffusion bonding – It is also known as diffusion welding and diffusion brazing. Diffusion welding is a solid-state welding process which produces coalescence of the faying surfaces by the application of pressure at high temperature. The process does not involve macroscopic deformation, melting, or relative motion of parts. A solid filler metal (diffusion aid) can or cannot be inserted between the faying surfaces.
Diffusion brazing – It is a brazing process which produces coalescence of metals by heating them to suitable temperatures and by using a filler metal or an in-situ liquid phase. The filler metal can be distributed by capillary action or can be placed or formed at the faying surfaces. The filler metal is diffused with the base metal to the extent that the joint properties have been changed to approach those of the base metal. Pressure may or may not be applied.
Diffusion burner – It is also known as a nozzle mix or non-premixed burner. It mixes fuel and air in the combustion zone, where the flame is formed. This means the fuel and air are not mixed before entering the burner head but instead come into contact and react within the combustion chamber.
Diffusion, clad material – It is the migration of alloying elements from the core into the cladding layer during thermal treatment. This can be detrimental to the properties and behaviour of both the core and cladding.
Diffusion coating It is a process whereby a base metal or alloy is either (i) coated with another metal or alloy and heated to a sufficient temperature in a suitable environment or (ii) exposed to a gaseous or liquid medium containing the other metal or alloy, hence causing diffusion of the coating or of the other metal or alloy into the base metal with resultant changes in the composition and properties of its surface.
Diffusion coefficient – It is a factor of proportionality representing the quantity of substance diffusing across a unit area through a unit concentration gradient in unit time.
Diffusion coefficient matrix – It is a square array of transport properties used in multi-component systems to relate mass or heat fluxes to multiple simultaneous concentration or temperature gradients. It extends Fick’s first law beyond simple binary mixtures.
Diffusion coefficient of carbon – It is a physical constant which measures how quickly carbon atoms move through a metal matrix (like iron or steel). It dictates the speed of important metallurgical processes like carburizing and case hardening, and is calculated based on Fick’s laws.
Diffusion-controlled dislocation creep – It is frequently called climb-controlled creep. It is a high-temperature deformation mechanism where materials continuously yield under constant stress. It relies on a repeating cycle: dislocations bypass structural obstacles via diffusion (climb) and then quickly move forward along slip planes (glide). This process is highly dependent on temperature (typically occurring above 0.4 times the material’s absolute melting point) and is mathematically described by the power-law creep equation.
Diffusion couple – It is an experimental arrangement where two different solid materials or alloys are held in intimate contact at their interface and heated to a specific temperature to study atomic interdiffusion.
Diffusion couple experiment – It is a technique where two different polished materials or alloys are pressed tightly together, heated to a specific high temperature, and held there to let atoms move across the shared boundary.
Diffusion creep – It refers to the deformation of crystalline solids by the diffusion of vacancies through their crystal lattice. Diffusion creep results in plastic deformation rather than brittle failure of the material. Diffusion creep is more sensitive to temperature than other deformation mechanisms.
Diffusion distance – It is the average length which atoms travel within a metal’s crystal lattice over a specific time. It fundamentally determines how deeply elements penetrate a metal and how fast microstructural changes (like phase transformations or heat treatments) occur. Diffusion distance relies on a simple approximation where the distance scales with the square root of time and the rate at which the atoms move.
Diffusion equation – It is also known as Fick’s second law. It calculates how the concentration of solute atoms changes over time within a metal’s crystal structure. It predicts processes like the hardening of steel or alloy homogenization.
Diffusion factor – It is frequently called Lieblein’s diffusion factor. It is an empirical blade-loading criterion used to measure local fluid deceleration and predict boundary layer separation or stall on compressor airfoils.
Diffusion flame – It occurs when fuel and an oxidizer are separate before burning. Combustion happens in a reaction zone where they meet and mix through molecular or turbulent diffusion. The burning rate depends on how fast the reactants come together, not on local chemical reaction speeds.
Diffusion flow – It is the net movement of mass, atoms, or molecules from an area of higher concentration to an area of lower concentration, driven by random thermal motion or chemical potential gradients. It governs transport phenomena in fluid dynamics, semiconductor doping, and heat transfer / mass transfer.
Diffusion flux – It is the net rate at which matter (atoms, ions, or molecules) flows through a unit cross-sectional area per unit of time. It is the fundamental parameter used to quantify mass transfer, typically moving from areas of high concentration to areas of low concentration.
Diffusion front – It is the advancing boundary or transitional zone where the concentration of a diffusing substance (such as atoms, ions, heat, or moisture) transitions from a high level to a base-line value inside a material or medium.
Diffusion kinetics – It is the study of how fast atoms, ions, or molecules move through solids, liquids, or gases. It uses concentration gradients and thermal energy to measure rates of mass transport, dictating processes like material hardening, doping in semiconductors, and chemical reactions.
Diffusion law – It refers to a mathematical relationship which describes the flux of particles moving from areas of higher concentration to areas of lower concentration, exemplified by Fick’s law, which states that the diffusion flux is proportional to the concentration gradient.
Diffusion layer – It is a localized zone where mass transport, atomic penetration, or concentration gradients occur near a material interface or boundary. It refers to a component which facilitates the transport of reactants from the flow field to the catalyst layer and products from the catalyst layer to the flow field, typically composed of a mixture of carbon cloth, carbon paper, and a microporous layer made of carbon black. It is important for ensuring effective conductivity and porosity in devices such as direct methanol fuel cells (DMFC).
Diffusion length – It is the average distance which photogenerated electrons and holes travel before charge recombination in a solar device, playing a critical role in the performance of photov-oltaic materials. It is the average distance a particle, charge carrier, or atom moves from its point of origin before changing state, recombining, or being absorbed.
Diffusion limitation – It is a constraint where the rate of an overall process, such as a chemical reaction, mass transfer, or heat exchange, is controlled by how fast molecules or ions move through a medium through diffusion rather than by the speed of the local reaction itself.
Diffusion-limited current density – It is the current density, frequently referred to as limiting current density, which corresponds to the maximum transfer rate that a particular species can sustain because of the limitation of diffusion.
Diffusion matrix – It is also called diffusion coefficient matrix. It is a mathematical array of values replacing a single scalar diffusion coefficient. It describes multi-component transport, anisotropic material properties, or network node transitions where the flow of a substance or data depends on multidirectional or multi-variable gradients.
Diffusion mechanism – It is the process by which atoms, ions, or molecules migrate through a medium (solid, liquid, or gas) from areas of high concentration to areas of low concentration driven by thermal energy and random atomic jumps.
Diffusion-mixed burners – In diffusion-mixed burners, the fuel and the oxidizer are separated and are not mixed prior to combustion, which begins where the oxidizer/fuel mixture is within the flammability range. Oxy-fuel burners are usually diffusion burners, primarily for safety reasons, to prevent flashback and explosion in a potentially dangerous system. Diffusion gas burners are sometimes referred to as ‘raw gas’ burners as the fuel gas exits the burner essentially intact with no air mixed with it. Diffusion burners typically have longer flames as compared to premixed burners. They do not have a high temperature hotspot, and usually have a more uniform temperature and heat flux distribution.
Diffusion model – It is defined as a generative modeling approach which progressively refines a basic distribution, typically Gaussian, through a series of denoising steps to approximate a specific empirical data distribution. These models are utilized for generating high-quality samples, performing image denoising, and applications in material science, including generating and optimizing materials with desired properties.
Diffusion model equation – It describes how physical quantities (like mass, thermal energy, or concentration) or probabilistic states (like noise in generative artificial intelligence) spread and change over space and time.
Diffusion multiple – It is an experimental assembly of three or more different metal or alloy blocks joined in close interfacial contact and heated to high temperatures to trigger thermal interdiffusion. This set-up creates continuous composition libraries and intermetallic compounds, allowing engineers to map phase diagrams rapidly.
Diffusion of innovations theory – It explains how, why, and at what rate new technical ideas, products, and engineering solutions spread through a social or organizational system through specific communication channels over time.
Diffusion path – It is the geometric or compositional trajectory, such as the shortest distance from a material’s interior to its surface, or a compositional curve mapped across phase diagrams in multi-component systems, along which mass, moisture, or atoms migrate.
Diffusion, precipitation, and non-equilibrium – These are core concepts which describe how matter moves, changes state, and behaves when subjected to unbalanced forces. Diffusion is the net movement of particles (atoms, ions, or molecules) from an area of higher concentration to an area of lower concentration, driven by a gradient in chemical potential. Precipitation refers to the formation of a solid phase from a solution, frequently occurring when a solution becomes supersaturated with a solute. Non-equilibrium describes a system which is not in a state of thermodynamic equilibrium. In such states, matter or energy is continuously transferred across the system, preventing it from resting in a state of uniform balance or minimum energy.
Diffusion problem – It is a physical and engineering issue governed by a diffusion partial differential equation, typically involving processes such as heat conduction and can be analyzed under steady-state conditions as an elliptic problem suitable for finite element methods (FEM).
Diffusion process – It is defined as the spontaneous movement of molecules or particles along a concentration gradient, occurring from regions of higher concentration to lower concentration until even distribution is achieved. It is a key phenomenon in transport processes, relevant in different applications across several disciplines. Diffusion process is the microscopic process by which atoms migrate within a solid or liquid metal. Atoms spontaneously move from areas of high concentration to areas of low concentration to achieve thermodynamic stability and uniformity.
Diffusion staining – It is the patchy surface discolouration which can occur as a result of diffusion in clad material.
Diffusion streak – It is the surface discolouration which can vary from gray to brown and found only on alclad products.
Diffusion term – It represents the mathematical rate at which mass, momentum, or thermal energy spreads through a system through random molecular motion, driven by a gradient in concentration, temperature, or partial pressure.
Diffusion theory – It mainly refers to physical transport models (like mass transfer and Fick’s laws) describing how particles or molecules move along a concentration gradient. It is also the study of how innovations spread through a population, involving analytical models to explain and predict the dynamics of adoption over time, categorized into groups such as innovators, early adopters, early majority, late majority, and laggards based on a normal distribution curve.
Diffusion time (t) – It is the characteristic time needed for mass, heat, or particles to spread across a specific spatial dimension (L) through diffusion, scaled by the diffusion coefficient (D). It is estimated using the scaling relation ‘t = L-square/D’.
Diffusion welding – It is a solid-state welding process which produces coalescence of the faying surfaces by the application of pressure at high temperature. The process does not involve macroscopic deformation, melting, or relative motion of parts. A solid filler metal (diffusion aid) may or may not be inserted between the faying surfaces.
Diffusion zone – It is the zone of variable composition at the junction between two different materials, such as in welds or between the surface layer and the core of clad materials or sleeve bearings, in which interdiffusion between the different components has taken place.
Diffusive coupling – It is an interaction where elements in a network influence each other based on the difference between their states, acting like a gradient flow to drive system synchronization.
Diffusive flux – It is the net quantity of a substance (mass, moles, or number of particles) which moves through a unit area per unit time. It is driven by a concentration gradient, moving particles from regions of high concentration to regions of low concentration.
Diffusive mass flux – It is the quantity of a specific chemical or substance which moves through a unit area per unit time strictly because of the random molecular motion driven by a concentration difference.
Diffusive mixing – It is a micro-level transport process where particles, molecules, or heat randomize and spread out because of the random individual movements, molecular collisions, or thermal fluctuations, reducing concentration gradients over time.
Diffusive regime – It is a transport state where the mean free path of particles, energy, or mass is much smaller than the system size. Random thermal or molecular collisions dominate, causing net movement to follow gradient-driven laws like Fick’s law or Fourier’s law rather than ballistic straight-line motion.
Diffusive transformation – It is also called reconstructive transformation. It is a solid-state phase change where atoms migrate long distances through thermal activation, breaking and reforming atomic bonds to create a new crystal structure and chemical composition.
Diffusive transport – It is the random, net movement of mass, energy, or charge from a region of high concentration (or temperature / potential) to a region of low concentration. It is driven by a gradient and occurs through random molecular collisions or particle agitation without bulk fluid motion.
Diffusivity – It is a fundamental physical property which dictates how quickly atoms, ions, or molecules migrate within a metal’s crystalline structure. It serves as a measure of a substance’s capacity to spread through a medium and is governed by Fick’s laws of diffusion. Diffusivity is expressed in SI (International System of Units) units of square meters per second.
Diffusivity coefficient – It is also called diffusion coefficient (D). It is a key value. It measures how fast a substance (like a gas, liquid, or heat) moves through a material. It shows the link between the flow of the substance and the change in its concentration.
Diffusivity constant – It is also called diffusion coefficient. It is a material property which measures how fast a substance, heat, or momentum moves through a medium. It links the rate of transfer (flux) to the driving force like a concentration or temperature change. Its standard unit is square meter per second.
Diffusivity equation – It is a linear partial differential equation which models the unsteady-state flow (pressure diffusion) of a slightly compressible fluid through a porous medium. It combines mass conservation, Darcy’s law, and a fluid compressibility relation.
Diffusivity ratio – It refers to the relative speed at which a substance spreads r moves through a material. It is a measure of how easily a substance can diffuse, frequently compared to another substance or the same substance in different conditions. In essence, it quantifies how quickly something diffuses or how ‘willing’ a material is to let something diffuse through it.
Digest – It is the controlled breakdown or softening of materials using heat, solvents, or biological agents, such as processing organic waste into biogas in an anaerobic digestion system.
Digested sludge – It is created through a biological process where micro-organisms break down organic matter in waste-water sludge. It is the product of either aerobic or anaerobic digestion of waste-water sludge, resulting in a stabilized material suitable for dewatering and further processing. This process reduces the volume and weight of the sludge, stabilizes organic matter, and frequently destroys pathogens. Digested sludge can be a valuable resource for land application or energy production.
Digital – It means that the data is represented by a series of digits. Several functions / values can be transmitted over a single pair of cables. It is a representation characterized by discrete levels and a discrete time axis, which is fundamental to modelling and simulating systems in modern engineering. This digital nature allows for the implementation of designs using logic or computational hardware, facilitating processes like digital synthesis and event-based modelling.
Digital audio – It is the audio data which is represented in a digital format, allowing for improved reliability, sound quality, and storage efficiency compared to traditional analog methods. It incorporates digital signal processing (DSP) for manipulation and can be recorded and played through digital audio interfaces that convert analog signals to digital and vice versa.
Digital base-band – It refers to a transmission method where voltage pulses represent bits or groups of bits, typically used in twisted-pair subscriber loops to optimize signal transmission. It is specifically employed in certain types of digital loops, such as HDSL (high-bit-rate digital subscriber line) and its derivatives.
Digital beam-forming – It is a method which utilizes digital processors in conjunction with an array of antennas to shape and direct energy towards desired directions while minimizing interference. It allows for improved signal-to-interference-plus-noise ratio (SINR) by controlling amplitude and phase, enabling the creation of multiple beams and improving performance in different applications such as communications and radar.
Digital camera – It is an electro-optical system which focuses incoming photons through an optical lens, converts light intensity into electrical charges through a solid-state sensor, and processes these signals into discrete binary data files for storage.
Digital circuit – It is an electronic system which processes signals using two discrete, fixed voltage levels. These two states represent binary values of logic 0 (low voltage / off) and logic 1 (high voltage / on), serving as the foundation for modern computers, micro-processors, and digital communication devices.
Digital coherent detection – It is an advanced technique which mixes an incoming modulated signal with a local reference oscillator and uses analog-to-digital converters and algorithms to recover full amplitude, phase, and polarization data. It maximizes data capacity and corrects signal errors in fibre optics.
Digital communication system – It transmits information using discrete, quantized signals (typically binary digits 0 and 1) rather than continuous wave-forms. It converts source data into a digital bit-stream, processes it for error control and modulation, and sends it across a physical channel.
Digital computation – It is the process of using discrete binary values (0s and 1s) to represent, process, store, and manipulate data and instructions through electronic logic circuits and micro-processors. It forms the core foundation for modern automated control systems, embedded devices, and computational hardware.
Digital computer – It is an electronic system which processes information in discrete, quantized form, typically using the binary code of 0s and 1s. It uses transistor circuits in two stable states (on / off, high / low voltage) to execute mathematical calculations, logic decisions, and automated control tasks at high speeds.
Digital control – It is a control system which processes signals in digital form.
Digital controller – It is a processor-based system, such as a micro-controller, programmable logic controller (PLC), or computer, which manages a closed-loop feed-back system by processing discrete numerical data, executing control algorithms through software, and regulating physical processes.
Digital control system – It is an arrangement of physical components and digital processors, like micro-controllers, DSPs (digital signal processors) or computers, which use feed-back loops and discrete-time algorithms to regulate the behaviour of continuous physical processes.
Digital conversion – It is the process of changing information from a continuous physical form into a set of discrete numbers or binary codes (zeros and ones) so that computers and digital systems can read, store, and process it.
Digital converter – It is very frequently an analog-to-digital converter (ADC). It is an electronic circuit which changes a continuous physical analog signal (like sound, light, or temperature voltage) into discrete binary numbers (zeros and ones) so a computer or micro-controller can process it.
Digital core – It is the central, integrated technology and data foundation which unifies an organization’s core operations, systems, and real-time data flows. It acts as the single source of truth and operational back-bone which powers automation, analytics, and advanced applications.
Digital data – It is the information recorded as discrete binary values (zeros and ones) which computers can process, while digital engineering is the practice of using these computer models and digital work-flows to design, build, and manage systems across their entire life cycle.
Digital detector – It is frequently a digital detector array (DDA) or flat-panel detector. It is an active electronic imaging device. It captures ionizing radiation, such as X-rays or gamma rays, and converts that energy instantly into discrete digital electrical signals. This replaces traditional photographic film in fields like non-destructive testing (NDT).
Digital detector array – It is frequently called a flat panel detector. It is an electronic device used in non-destructive testing (NDT) to convert X-rays or gamma rays into a real-time digital image. It replaces traditional radiographic film.
Digital divider – It typically refers to a frequency divider (a logic circuit which reduces a high clock frequency into a lower one) or an arithmetic logic circuit which performs binary division on numbers.
Digital domain – It is the virtual sphere of electronic information, communication systems, and computer-based media where data is processed as binary code (ones and zeros). It spans everything from online networks and software to digital imagery and virtual environments.
Digital electronics – It is a branch of electronics which processes information using discrete, two-state signals represented by binary numbers (0 and 1). Instead of continuous voltage levels like analog systems, digital circuits use clear on / off or high/ low voltage steps to perform reliable calculations, logic operations, and data storage.
Digital elevation model – It is a 3D digital representation of a planetary surface’s topography, typically focusing on bare-earth ground elevations (excluding trees and buildings) using raster grids or vector points.
Digital engineering – It is an integrated practice which uses computer models, simulations, and data as the main means to design, build, and manage systems across their entire life cycle. It replaces traditional paper documents with a shared, single source of truth.
Digital factory – It is a connected network of digital models, tools, and data systems used to plan, simulate, and manage manufacturing operations and product life-cycles in real time. It bridges physical shop floors with virtual IT (information technology) platforms to optimize production efficiency.
Digital filter – It is a system or mathematical algorithm which processes a sampled, discrete-time signal to remove noise, improve specific features, or select particular frequency ranges. Unlike analog filters made of physical parts like resistors and capacitors, digital filters use software code or specialized digital processors.
Digital filtering – It is a signal processing method which uses mathematical operations and algorithms to change or improve discrete-time digital signals by removing unwanted noise, highlighting specific frequencies, or separating combined data streams.
Digital filter transfer function – It is a mathematical representation which describes the relationship between the input and output signals of a digital filter, which can be derived from an analog filter or designed directly from specific performance specifications.
Digital frequency – It is a normalized measure of how much a wave changes or cycles per discrete sample, expressed as ‘omega = w x T, where ‘w’ is angular frequency and ‘T’ is the sampling period. In instrumentation, it refers to a numerical readout from a device counting signal pulses per second.
Digital front – It is very frequently referred to as a ‘digital front door’. It is a technology-driven strategy and connected set of online tools which serves as the main entry point for users or customers to interact with an organization. It includes hardware engineering (digital front-end in radio transceivers) and commercial printing (digital front end or DFE print controllers).
Digital front end – It is a specialized hardware and software system which acts as the command centre between a user work-flow and a production device, very frequently a high-speed digital printing press. It translates design files into printer-ready data and manages colour accuracy, job queues, and press performance.
Digital function – It is also called logic function. It is a mathematical or logical operation which processes one or more discrete binary inputs (0 and 1) to produce a specific binary output. It maps input combinations to outputs using the rules of Boolean algebra. m
Digital gate – It is also called logic gate. It is a basic building block of digital electronics. It is an electronic circuit which takes one or more binary inputs (0s and 1s) and follows a specific rule to produce a single binary output.
Digital image correlation – It is a non-contact, optical measurement technique used to track and map deformation, displacement, and strain on the surface of a material. By comparing sequential images of a test object before and under load, engineers can create comprehensive, full-field surface strain maps. It is defined as a non-contact method that maps one digital image onto another to retrieve the displacement field on a sample’s surface by maximizing a correlation coefficient derived from pixel intensity arrays. It can be applied in 2D or 3D, with the latter using multiple cameras or 3D imaging devices.
Digital image correlation (DIC) technique – It is a non-contact optical method which tracks pixel patterns on a material’s surface using cameras to measure full-field shape, displacement, and strain. By comparing digital pictures taken before and after a load is applied, it computes exact movement.
Digital image processing – It is the use of a digital computer for processing the digital images through an algorithm. As a subcategory or field of digital signal processing, digital image processing has several advantages over analog image processing.
Digital images – These images are the electronic snapshots taken of a scene or scanned from documents, such as photographs, manuscripts, printed texts, and artwork. The digital image is sampled and mapped as a grid of dots or picture elements (pixels). Each pixel is assigned a total value (black, white, shades of gray or colour), which is represented in binary code (zeros and ones).
Digital imaging system – It combines hardware and software to capture, convert, process, store, and display visual information as numeric data (pixels). It replaces traditional analog methods, like film photography or physical X-rays, with electronic signals which computers can instantly edit, share, and analyze.
Digital instrument – It is an instrument which represents the measured value in the form of the digital number. It works on the principle of quantization. The quantization is the process of converting the continuous input signal into a countable output signal.
Digital integrated circuit – It is a tiny micro-chip made of semi-conductor material which processes discrete binary signals (0s and 1s) using transistors acting as electronic switches. These chips form the core logic and computing power behind modern electronics.
Digital light processing – It is an optical technology which uses micro-chips with tiny mirrors to reflect light and create images or cure liquid resin. It is widely used in digital projectors, movie theaters, and 3D printers.
Digital manufacturing – Digitalization of controls during the manufacturing process helps identifying and automatically correcting the flaws in the products during each step of the production process. This in turn improves the product acceptance rates.
Digital measuring device – A digital measuring device is that in which the value of the measured physical quantity is automatically represented by a number on a digital display or by a code, that is, a set of discrete signals. Digital measuring devices can be divided into digital measuring instruments and digital measuring transducers. Digital measuring instruments are self-contained devices which automatically present the value of the measured quantity on a digital display.
Digital meter – It is an electronic tool which measures values like voltage, current, or power usage and shows the results as numbers on a screen. It replaces old mechanical dials and moving needles with clear digital numbers.
Digital method – It is an approach which uses online and digital technologies to collect, process, and analyze data. Instead of just moving old offline tasks to a computer screen, it studies natively digital objects, like hyperlinks, likes, and shares, to understand broader social and technical patterns.
Digital microfluidics – It is a lab-on-a-chip technology which controls tiny droplets of liquid (pico-litres to micro-litres) using an array of electrical electrodes instead of fixed physical channels.
Digital micro-mirror – It is a microscopic, highly reflective aluminum mirror used in optical semi-conductor chips. Millions of these tiny mirrors combine to form a digital micro-mirror device (DMD), acting as fast pixel switches which tilt back and forth to control light.
Digital micro-mirror device – It is a micro-electro-mechanical semi-conductor chip featuring an array of millions of tiny, independently tiltable aluminum mirrors. Each mirror acts as a pixel which reflects light on or off to rapidly modulate light paths for projectors and optical systems.
Digital microscope – It is a modern type of microscope which does not use an eye-piece. Instead, it uses a built-in digital camera and lens to capture magnified images and display them directly on a computer screen, a television (TV), or an attached liquid-crystal display (LCD) monitor.
Digital microscopy – It is the field and process of using a specialized microscope equipped with a digital camera and computer software to capture, display, and analyze magnified images on a monitor screen, completely omitting traditional physical eyepieces.
Digital modulation – It is the process of encoding discrete digital data (binary 0s and 1s) onto a continuous analog carrier wave. It changes specific properties of the carrier wave, like its amplitude, frequency, or phase, so that data can travel efficiently and reliably through wires or wireless space.
Digital object – It is a single item or set of computer-readable data which has structured content and a unique identifier. It includes both the core information file and the metadata needed to find, use, and manage it.
Digital oscilloscope – It is an electronic test tool which samples electrical voltage signals, converts them into digital numbers using an analog-to-digital converter, and stores them in memory to display a wave-form graph on a screen. It shows how voltage changes over time.
Digital preservation – It is a process by which digital data is preserved in digital form in order to ensure the usability, durability and intellectual integrity of the information contained therein. A more precise definition is ‘the storage, maintenance, and accessibility of a digital object over the long term, normally as a consequence of applying one or more digital preservation strategies’.
Digital printing – It is a modern method which sends a file straight from a computer to a printer. It puts ink or toner right onto paper, fabric, or other items. It skips the old steps of making metal plates or screens.
Digital receiver – It is an electronic device or circuit which accepts digital or analog input signals, converts or demodulates them using digital processing, and translates them into viewable or audible data like TV (television) programmes, audio, or radio streams.
Digital recording – It is a process where physical signals, like sound waves, are turned into numbers. It changes continuous waves into a stream of zeros and ones (binary code) which computers can save, read, and share.
Digital record-keeping – It is the systematic, computer-based management of creating, receiving, storing, retrieving, and disposing of information. As per International Organization for Standardization standard ISO 15489 specification for records management, these digital records are to retain four core pillars to be considered legally valid namely authenticity, reliability, integrity, and usability.
Digital record-keeping standard – It defines the guidelines and technical specifications for managing, securing, and preserving electronic information. Grounded in global benchmarks like the International Organization for Standardization standard ISO 15489-1, it ensures digital documents remain authentic, reliable, complete, and accessible as legal or business evidence throughout their entire lifecycle.
Digital repository or archive – The digital repository is where digital content, assets are stored and can be searched and retrieved for later use. The repository supports mechanisms to import, export, identify, store and retrieve digital assets. Putting of digital content into a repository enables the people to manage and preserve it, and hence derive maximum value from it.
Digital sampling oscilloscope – It is an advanced test instrument which measures extremely high-speed, repetitive electrical signals by capturing tiny voltage pieces across successive wave-form cycles. It reconstructs these low-frequency equivalent samples into a clear, continuous visual representation on a screen.
Digital sequence – It refers to a discrete representation of a continuous analog signal, consisting of a series of numeric values got through the processes of sampling and quantization. This sequence can be easily stored and processed on a digital computer.
Digital signal – A digital signal is a signal which represents data as a sequence of discrete values. At any given time, it can only take on, at most, one of a finite number of values. In contrast the analog signal which varies in a continuous fashion and takes on infinity of values in any given range, the digital signal varies in discrete steps and hence takes up only finite different values in a given range.
Digital signal processing – It is the mathematical manipulation and analysis of sensor data (like acoustic emissions, ultrasound, or eddy currents) using specialized microprocessors to detect material flaws, characterize microstructures, or enable data transmission through solid metal barriers.
Digital signal processing algorithms – These algorithms mathematically analyze and manipulate digitized physical sensor data. They are critical for processing raw analog metrics, such as acoustic emissions, ultrasonic vibrations, and thermal signatures, into quantifiable data used to monitor structural health, detect micro-fractures, and control manufacturing processes.
Digital signal processing system – It is a set-up or device which takes real-world physical signals (like sound or light), turns them into numbers, changes or improves those numbers using mathematics, and then frequently turns the numbers back into normal physical signals.
Digital signal processing tool – It is a software programme, algorithm, or specialized hardware processor used to measure, filter, and modify digitized real-world signals like sound, video, and sensor data. These tools change continuous physical waves into numbers to analyze and improve data.
Digital signal processor – It is a specialized micro-processor chip to perform mathematical computations on digitized real-world signals at ultra-fast speeds. It translates, filters, and manipulates streaming data like audio, video, temperature, and voice to extract useful information or improve system performance.
Digital signal transmission – It is the transfer of data encoded as discrete, distinct electrical, light, or radio pulses representing binary values of zeros and ones (0 and 1). Instead of continuous smooth waves, it uses finite states, providing high resistance to noise and signal corruption.
Digital simulation – It is the use of computer-based mathematical models to imitate, test, and analyze how a real-world system or process behaves over time. It lets teams run ‘what-if’ experiments and view outcomes in a virtual environment before making physical changes.
Digital simulator – It is a computer programme which models and predicts the behaviour of real-world or abstract systems over discrete time steps. It tests designs and processes without physical risks or high prototyping costs.
Digital single-lens reflex camera – It is a type of digital camera which uses a mechanical mirror system and a single lens to both preview and capture images, recording them onto an electronic sensor instead of film.
Digital storage oscilloscope – It is an electronic test tool which captures, converts, and stores electrical voltage signals in digital memory. Unlike old analog scopes which show signals only in real-time, a digital storage oscilloscope (DSO) lets people freeze, save, and analyze wave-forms indefinitely.
Digital subscriber line – It is a broadband technology which delivers high-speed internet access using standard copper telephone lines. It allows the use of the internet and make voice phone calls simultaneously without interference, utilizing existing telecommunication infrastructure.
Digital system – It is an electronic or computational arrangement which processes, stores, and communicates information using discrete, quantized values, typically binary digits (0s and 1s). Unlike analog systems which rely on continuous physical signals, digital systems use high and low voltage states to perform reliable, noise-resistant operations.
Digital tachometer – It is an electronic instrument which measures and shows the rotational speed of a shaft, disk, or motor in revolutions per minute (rpm) on a numerical digital screen. It provides precise, real-time feed-back with high accuracy.
Digital television – It is an advanced broadcasting technology which transmits video and audio signals using digital binary codes (0s and 1s). It replaces older analog systems, offering much sharper high-definition images, clearer sound, and more channels within the same radio frequency spectrum.
Digital thermometer – It is an electronic device used to measure temperature. It uses a small sensor called a thermistor to detect heat changes, converts that data into an electrical signal, and shows the clear number on an LCD (liquid-crystal display) or LED (light-emitting diode) screen.
Digital to analog conversion – It is the process of changing a digital signal, made of discrete binary numbers (0s and 1s), into a continuous physical signal like voltage or current. This conversion allows computers and digital devices to drive real-world analog outputs like sound, light, and movement.
Digital to analog converter – It is a device in which inputs are a binary number and outputs are an analog voltage or current signal. It is an electronic circuit which transforms discrete digital data (such as binary combinations of 1s and 0s) into a continuous analog signal (voltage, current, or electric charge). It acts as the necessary bridge between digital processors and the physical, analog world.
Digital transfer function G(z) – It is the ratio of the Z-transform of the output signal ‘Y(z)’ to the Z-transform of the input signal ‘X(z)’ under zero initial conditions. It models discrete-time linear systems.
Digital transmission – It is the transfer of data or information as discrete binary pulses (representing 1s and 0s) across a physical or wireless network medium. It replaces continuous analog waves with distinct states, allowing clear, noise-resistant communication over long distances.
Digital transmission system – It is a communication framework which transfers information using discrete electrical, optical, or radio pulses representing binary values of 0 and 1. It converts data into a digital format to provide higher accuracy, lower noise, and efficient long-distance signal recovery compared to analog systems.
Digital transmitter – It is an electronic device which converts data, sensor readings, or physical measurements into coded digital signals (binary data packets) and sends them over a wired or wireless medium to a receiver.
Digital twin – It is a virtual representation of a physical object or system that uses real-time data to accurately reflect its real-world counterpart’s behaviour, performance and conditions. Digital twins enable continuous monitoring, simulation and analysis of an object, product or system over the course of its life-cycle, from design and production to maintenance and decommissioning. They can also incorporate external processes and critical variables that affect an asset’s performance. A key feature is real-time, two-way data exchange between the object and its virtual replica, helping ensure that simulated conditions accurately reflect the physical world. Organizations can also connect multiple digital twins to model more complex systems in service of a larger digital transformation.
Digital video application – It is a software programme or system used to create, edit, play, transmit, or manage moving visual images stored in binary data formats. These tools process pixel sequences and audio streams to run on computers, phones, and web platforms.
Digital video recorder – It is an electronic device which takes analog video signals from security cameras, converts them into digital data, and stores the footage on a hard drive. It serves as the central hub for wired CCTV (closed-circuit television) security systems.
Digital voltmeter – It is an electronic tool used to measure electrical voltage. It shows the result as a clear number on a screen. It works with both direct current (DC) and alternating current (AC).
Digital watermarking – It is the process of hiding a marker, code, or message inside digital media like images, audio, or video. It helps prove ownership, track copyright use, and check if a file has been changed.
Digital wrapper – It is a data structure, container format, or piece of code which encapsulates other data signals, files, or legacy software programmes. It adds a uniform layer of metadata, security, or management control so the underlying content can work smoothly within a new network or system.
Digitization – It is the process of converting information into a digital format. In this format, information is organized into discrete units of data (called bits) which can be separately addressed (normally in multiple-bit groups called bytes). This is the binary data which computers and several devices with computing capacity can process. Text and images can also be digitized. Similarly, digitization of audio and video presentations is also possible.
Di-glycol-amine – It, also known as 2-(2-aminoethoxy)-ethanol or Di-ethylene glycol-amine. It is a colourless, slightly viscous liquid with a mild amine odour. It is a primary amine which is miscible with water, alcohols, and aromatic hydro-carbons, but less so with aliphatic hydro-carbons.
Dihedral angle – It is the geometric angle formed between two intersecting planes. It is measured on a third plane which sits at a right angle to the line where the first two planes meet.
Di-hydrate – it is a chemical compound containing exactly two molecules of water of crystallization bound to each molecule or unit cell of the substance. These water molecules are structurally integrated into the crystal lattice without altering the chemical nature of the primary compound.
Di-hydrogen ammonium phosphate – It is also known as mono-ammonium phosphate (MAP). It is an inorganic chemical salt with the formula NH4H2PO4. It appears as a white powder or colourless crystal, highly soluble in water, and serves as a major component in agricultural fertilizers and dry-chemical fire extinguishers.
Di-isocyanate – It is a reactive organic chemical building block containing two isocyanate groups (-N=C=O). It is chiefly used to manufacture poly-urethane plastics, foams, coatings, and adhesives.
Di-iso-propyl-amine – It a secondary amine. It is a colourless liquid with a fishy, ammonia-like odor. It is a versatile chemical used as a precursor in organic synthesis, a nucleophile, and in the production of certain herbicides and rubber vulcanization agents.
Dike – It is also spelled as dyke. It is a specialized seal used to prevent blow-by during core blowing operations. It minimizes the formation of metal ‘fins’ by creating a static back-pressure between the core box seal and the core cavity when sand is being blown into the mould. In geology, a dike is a sheet of rock which is formed in a fracture of a pre-existing rock body. Dikes can be either magmatic or sedimentary in origin. Magmatic dikes form when magma flows into a crack then solidifies as a sheet intrusion, either cutting across layers of rock or through a contiguous mass of rock. Clastic dikes are formed when sediment fills a pre-existing crack.
Diketonate – It is a coordination compound or complex formed when a diketone (specifically a beta-diketone) loses a proton and binds to a metal ion. These molecules act as chelating ligands, using two oxygen atoms from their carbonyl groups to grip the metal centre and create stable ring structures.
Diketone – It is an organic compound which contains two carbonyl (C=O) ketone groups within the same molecule.
Dilatancy – It is the tendency of a densely packed, granular material or metal powder to expand in volume when subjected to shear stress or deformation.
Dilatant – It is a reversible increase in viscosity with increasing shear stress.
Dilatant fluid – It is a non-Newtonian material whose viscosity increases when it is subjected to force, stress, or a higher rate of shear strain. Instead of flowing smoothly when mixed or hit quickly, it gets thicker, harder, and acts more like a solid.
Dilatant substance – It is frequently called a shear-thickening fluid. It is a non-Newtonian material which becomes thicker and more solid under applied stress or pressure. Unlike regular liquids, if a person hits or squeezes a dilatant fluid quickly, its viscosity increases, causing it to resist flow and temporarily behave like a solid.
Dilatational component – It refers to the portion of stress, strain, or deformation that changes the volume of a material without altering its shape. It governs purely volumetric changes (expansion or contraction) and is typically contrasted with the deviatoric component, which governs shape change (shear).
Dilation due to solidification – It is also called solidification expansion. It refers to the volume expansion some materials undergo as they transition from a liquid to a solid. While most metals and alloys shrink (contract) as they cool and freeze, a few unique elements and specific alloys dilate because of the open, low-density crystal structures they form upon freezing.
Dilatometer – It is an instrument for measuring the linear expansion or contraction in a metal resulting from changes in such factors as temperature and allotropy.
Dillamore’s criteria – It normally refer to the Dillamore criteria for plastic instability. This analytical threshold is used to predict when localized necking or failure is going to occur in sheet metals during deformation processes like deep drawing. It establishes that localized necking (where the metal thins and tears in a specific area) occurs when the rate of strain hardening falls below the rate of geometric softening caused by the thinning material. The criterion is widely cited for explaining and predicting the limits of sheet metal formability.
Dilemma game – It is most famously known in game theory as the prisoner’s dilemma. It is a decision-making scenario where two rational players acting in their own self-interest make choices which result in a sub-optimal outcome for both, failing to achieve the best cooperative result.
Diluent – It is normally a liquid inert substance added to some other substance or solution so that the volume of the latter substance is increased and its concentration per unit volume is decreased.
Dilute acid hydrolysis – It is a chemical reaction which uses a low-concentration acid solution (like sulphuric acid or hydrochloric acid) at high heat to break complex plant fibres, such as cellulose and hemicellulose, down into simple, fermentable sugars.
Dilute acid pre-treatment – It is a chemical process used to break down plant biomass (like wood or crop waste) by treating it with a weak acid solution at high heat. This method dissolves hemicellulose and exposes the hard cellulose, making it easier to convert into sugars and bio-fuels.
Dilute and concentrated acid hydrolysis – These are chemical processes used to break down complex carbo-hydrates, such as cellulose and hemicellulose in plant biomass, into simple, fermentable sugar monomers like glucose. They differ mainly in the strength of the acid solution used and the operating temperatures needed.
Dilute aqueous solution – It is a liquid mixture where water is the solvent (the dissolving medium) and the dissolved solute (typically metallic ions from leached ores) is present in very low concentrations, normally parts per million (ppm). Hydro-metallurgical extraction relies heavily on these solutions. Since a low-grade ore contains only a small fraction of metal, leaching it with a reagent (like a dilute sodium cyanide solution for gold) yields a lean, dilute aqueous mixture. Specialized processes such as solvent extraction and ion exchange are then used to separate, purify, and concentrate the desired metals from the bulk water.
Dilute magnetic semi-conductor – It is a non-magnetic semi-conductor material doped with a small percentage of magnetic ions (such as transition metals), combining both traditional electronic conductivity and ferro-magnetism.
Dilute nitride – It is a class of III-V semi-conductor alloy where a very small fraction (typically around 1 % to 3 %) of group-V atoms in the crystal lattice is replaced by nitrogen. This tiny addition of nitrogen drastically alters the physical properties of the host material.
Dilute nitride alloy – It is a type of semi-conductor made by adding a very small quantity of nitrogen, normally less than a few percent, into a standard III-V semi-conductor host lattice like gallium arsenide. This tiny addition of nitrogen causes a large drop in the material’s band gap.
Dilute phase – It is a pneumatic conveying method where solid particles are completely suspended in a continuous, high-velocity stream of gas or air inside a pipe-line. It features low solid-to-air ratios and low operating pressures, making it ideal for robust, free-flowing materials.
Dilute phase conveying system – It is a high-speed pneumatic method which uses a continuous stream of air or gas to transport dry bulk powders and granules in complete suspension through a pipeline. It operates at high velocities (typically 15 meters per second to 30 meters per second) and low pressures (under 0.1 mega-pascal).
Dilute phase suspension flow – It is a pneumatic conveying method where solid particles are continuously kept floating and dispersed inside a high-speed gas or air stream through a pipe-line. It features low material-to-air ratios, fast velocities (typically 15 meters per second to 30 meters per second, and low operating pressures.
Dilute solution – It is a system with a high degree of dilution, where particle–particle interactions are negligible, allowing for simplified analysis of the solution’s properties. Dilute solution is a liquid or solid metal alloy containing a minor concentration of solute atoms dissolved in a primary solvent. Since solute atoms are widely separated, interactions between them are negligible, allowing their thermodynamic behaviour to be accurately described by Henry’s law.
Dilute sulphuric acid – It is a clear liquid made by mixing pure sulphuric acid (H2SO4) with a lot of water. It has a low acid quantity and a high-water quantity. It acts as a strong acid and a good electricity carrier. Dilution – It is the process of lowering the concentration of a solute in a solution by simply adding more solvent to the solution, such as water. Diluting of a solution entails adding more solvent without adding more solute.
Dilution air – It is clean, fresh air added to a gas stream, room, or system to mix with and lower the concentration of pollutants, toxic fumes, heat, or exhaust gases. It reduces harmful levels down to safe, acceptable limits through mixing rather than direct capture.
Dilution factor – When diluting a sample, it is the ratio of the final volume or mass after dilution to the volume or mass of the sample before dilution.
Dilution method – It is a process used to lower the concentration of a solute in a solution by adding more solvent, such as water. It keeps the total quantity of solute constant while increasing the total volume.
Dilution, mining – It means that the rock that is, by necessity, removed along with the ore in the mining process, subsequently lowering the grade of the ore.
Dilution rate – It defines the proportion of a concentrated substance (solute) mixed with a liquid diluent (solvent) to achieve a desired concentration. It is normally expressed as parts of concentrate to parts of water or total volume (e.g., 1:10 meaning 1 part product to 9 or 10 parts liquid).
Dilution ratio – It is a guide which shows how much concentrated product (solute) a person is to mix with water or another liquid (solvent). It is written as two numbers like 1:4 or 1:10. The smaller number (normally 1) is the product, and the larger number is the water (solvent).
Dilution zone – It is frequently called a zone of initial dilution or mixing zone. It is a specific area where a discharged fluid, substance, or waste mixes with a receiving medium (like a body of water or ambient air) to reduce its concentration to safe levels.
Dilutive internal concentration polarisation – It is a process in forward osmosis where water moves through the membrane and dilutes the draw solution inside the porous support layer. This dilution lowers the effective osmotic pressure difference across the membrane, which slows down the water flow rate.
Dimensional accuracy – It is the degree to which a manufactured part’s physical dimensions match the exact measurements specified in its design or CAD (computer-aided design) model. It ensures parts function, interact, and fit together correctly without assembly failures, structural issues, or premature wear.
Dimensional analysis – It is also called the factor-label method or unit factor method. It is a problem-solving technique which uses the fundamental dimensions (such as mass, length, and time) and units of physical quantities to convert measurements, verify equation correctness, and model complex systems.
Dimensional analysis of convection – It uses the Buckingham Pi theorem to group physical variables into dimensionless numbers. For forced convection, variables like the heat transfer coefficient (h) depend on fluid properties and flow speed. This process simplifies complex equations into core groups like the Nusselt, Reynolds, and Prandtl numbers.
Dimensional approximation – It is the process of replacing a complex, high-dimensional system, dataset, or function with a simpler, lower-dimensional model while retaining important information. It is used in data science, mathematics, and engineering to manage massive variables and avoid computational limits.
Dimensional array – It is a data structure which stores multiple items of the same data type under a single variable name. Each item or element is accessed using an index number, also called a subscript. The number of indices needed to find an item tells people how many dimensions the array has.
Dimensional case – It typically refers to a continuous, gradient-based approach to classifying conditions or phenomena along multiple quantitative axes or degrees of severity, rather than sorting them into rigid, categorical ‘yes / no’ groups.
Dimensional consideration – It means thinking about the size, measurements, or physical units of an object, system, or mathematics equation. It ensures that calculations use the correct base units (like length, mass, or time) and that physical laws make sense before you build or test something.
Dimensional constant – It is a physical quantity which has a fixed numerical value and clear physical dimensions (such as mass, length, or time). Its value and units do not change, but its numerical representation depends on the system of units used.
Dimensional control – It is the process of using precise measurement and surveying techniques to ensure that manufactured parts, structural components, and industrial assemblies match exact design specifications and fit together properly.
Dimensional convection – It refers to heat and mass transfer through fluid motion analyzed or restricted across specific spatial dimensions (such as 1D, 2D, or 3D systems), or evaluated using dimensional analysis of convection to group physical variables into dimensionless numbers.
Dimensional convolution – It is a mathematical operation which combines two functions or signals across one or multiple dimensions. It slides a small grid of values called a kernel or filter over an input matrix, multiplies overlapping values, and adds them up to compute feature maps or transform data.
Dimensional defects – These are mainly related to the shape and dimensions. During the rolling of a material, there can be different defects which can cause the shape not to be as desired or the measurements not to fall within the required tolerances. The majority of the frequent causes of dimensional defects are because of the poor adjustments to the mill control and tension while rolling.
Dimensional design – It very frequently refers to dimensional modelling in data warehousing, a database structure optimized for fast data retrieval and reporting. It organizes information into facts (numerical measurements) and dimensions (descriptive context like time, product, or location). In visual arts, it refers to creating objects with physical depth (3D).
Dimensional discrete – It refers to the representation of finite-extent images as a weighted sum of two-dimensional frequency components, allowing for computable and manipulable frequency-domain representations in computer science.
Dimensional discrete concept – It typically refers to a data field, signal, or mathematical space that has a specific number of independent directions or axes (dimensional), while existing as separate, individual, and countable units rather than a smooth, unbroken continuum (discrete).
Dimensional dislocation – It is a one-dimensional linear crystallographic defect representing an abrupt mismatch or irregularity in a material’s regular atomic lattice structure.
Dimensional disturbance – It refers to a spatial or volumetric perturbation, such as a three-dimensional variation in flow velocity, pressure, or structural geometry, which disrupts a stable baseline system, normally analyzed in fluid dynamics, control theory, and material stability.
Dimensional domain – It defines the bounded coordinate space or set of input variables ‘xL = x or below = xU or below’ which dictates the operational limits, physical boundaries, or valid numerical values for a system, model, or testing process.
Dimensional eddy – It typically refers to either a swirling vortex structure analyzed in a specific number of spatial dimensions (such as 2D or 3D turbulence in fluid dynamics) or a dimensional analysis used to define the physical scale, viscosity, and energy of turbulent eddies.
Dimensional face – It is an individual flat or curved surface which bounds a solid object. In advanced mathematics or polytope theory, a face can refer to a feature of any dimension (k-dimensional face), ranging from a point vertex (0D) to a line edge (1D) up to a volumetric facet.
Dimensional factor – It is a specific number set by shipping carriers to convert a package’s volume (length × width × height) into an equivalent billable weight. Carriers charge for whichever is higher namely the actual scale weight or this calculated dimensional weight.
Dimensional feature space – It is a multi-dimensional mathematical space where each axis represents an individual input variable (feature) from a dataset. Every single data sample forms a distinct coordinate point or vector within this space, allowing machine learning systems to measure similarity, cluster groups, and find patterns.
Dimensional finite element analysis – It is a computer-based method which splits a complex physical structure into small, simple pieces called finite elements. It solves equations on these small pieces to predict how the whole item reacts to forces, heat, or vibration.
Dimensional flow – It refers to the classification of fluid flow based on the number of coordinates which describe the fluid velocity, with one-dimensional flow depending on one coordinate, two-dimensional flow on two coordinates, and three-dimensional flow on three coordinates.
Dimensional flow field – It is a spatial representation of fluid motion where the number of spatial coordinates (one, two, or three) defines the fluid velocity components and properties change across position and time.
Dimensional Fourier transform – It is a mathematical operation which transforms a multi-dimensional signal, such as an image, into the spatial frequency domain, allowing for the analysis and filtering of the signal’s periodicities and characteristics. In the case of two dimensions, it involves a double integral or discrete summation to evaluate the signal’s variation in both spatial dimensions.
Dimensional frame – It typically refers to a structural system analyzed in two-dimensional (2D) or three-dimensional (3D) layouts, or a set of measurements defining the physical size, depth, and opening of a fitted object like a picture frame or eyeglasses.
Dimensional function – It very frequently refers to a mathematical function whose domain relies on multiple independent spatial or temporal coordinates, such as f(x, y) or f(x, y, z), making it a multi-variable or multi-dimensional signal. Depending on the context, the term can also describe physical dimensions of quantities or gauge functions in advanced topology.
Dimensional geometry – It is the mathematical study of the size, shape, and relative position of objects based on the number of independent coordinates or directions needed to locate a point within a space.
Dimensional homogeneity – It is the rule that every additive term in a physical equation is required to have the exact same base dimensions (such as mass, length, and time). If the dimensions do not match across every term, the equation is invalid.
Dimensional hyperplane – It is a flat subspace of a higher-dimensional space which has a dimension one less than the space it lives in. It splits that space into two separate halves.
Dimensional image – It is a visual display defined by spatial measurements like width, height, and depth. It ranges from flat, two-dimensional (2D) photos showing only area to three-dimensional (3D) models, holograms, or digital render volumes that add physical depth and realistic volume.
Dimensional incompressible flow – It is a fluid motion regime where the material density of a moving fluid parcel remains constant over time (dρ/dt = 0), typically analyzed across spatial dimensions (such as 2D or 3D) when flow speeds stay well below the medium’s speed of sound (Ma = less than 0.3).
Dimensional input – It refers to data or a signal which possesses multiple independent variables, coordinates, or spatial axes (such as length, width, height, or multiple feature columns) fed into a system, model, or function. In machine learning and software design, it defines the shape, size, or number of feature dimensions needed by an input layer or user interface.
Dimensional inspection – It is a critical quality control process which measures the physical geometry and dimensions of a part or assembly to ensure it conforms to the tolerances specified in engineering drawings or CAD (computer-aided design) models. It verifies features like length, width, angle, and flatness.
Dimensionality reduction technique – It is a mathematical method used to decrease the number of input variables or features in a dataset while keeping its most important information. It helps solve complex data problems, speeds up computer processing, and stops machine learning models from memorizing noise.
Dimensional limits – These limits define the maximum and minimum permissible sizes within which a manufactured part is required to fall to function correctly. These boundaries are explicitly set to account for manufacturing imperfections while ensuring inter-changeable parts assemble properly and perform as intended.
Dimensional management – It is an engineering design methodology which aims to absorb as much variation as possible without affecting the function of the product. It does this through the optimal selection of datums, feature controls, assembly methods, and assembly sequence. It differs from the conventional practice of assigning tolerances to drawings prior to release in that it is more systematic and more global in outlook and uses three-dimensional tolerance analysis computer aided engineering tools.
Dimensional matrix – It is a pair consisting of an algebra and a subset of that algebra raised to a power. It is used in computer science to represent mathematical structures and relationships between elements.
Dimensional method – It is also called dimensional analysis. It is a problem-solving tool. It uses base units like mass, length, and time to convert units, check if equations are correct, or find relations between physical variables. It works by multiplying values by conversion factors so unwanted units cancel out.
Dimensional model – It refers to the physical implementation of a denormalized entity relationship structure used in data marts and data warehouses. It is normally used in specialty databases.
Dimensional modelling – It is a design technique used in data warehouses to organize data for fast and easy reporting. It breaks data into facts (numbers to measure) and dimensions (descriptive context like who, what, and where). This structure makes queries run faster and helps organizer users understand the data easily.
Dimensional normal distribution – It is also called a multivariate normal distribution). It extends the standard single-number bell curve to a group of multiple variables. It shows how a set of related data values spread out in a multi-step space. Each single part of the group acts like a normal bell curve.
Dimensional observer – It is also called multi-dimensional observer. It is a mathematical mapping or algorithm used in control systems and fuzzy set theory. It estimates internal state variables of a system, or tracks multiple attributes of an object, across defined dimensions or coordinates.
Dimensional patterning – It refers to the creation or arrangement of structures, data, or features across specific spatial or numerical dimensions.
Dimensional polyhedron – It is a geometric solid or its multi-dimensional counterpart (n-dimensional polytope) bounded by flat polygonal faces, straight edges, and sharp vertices. In higher dimensions or specialized analysis, it represents the solution space of linear inequalities.
Dimensional problem – It involves setting the precise physical scale, spatial boundaries, and coordinate degrees of freedom (1D, 2D, or 3D) needed to analyze, model, or manufacture a system. It defines whether a problem can be simplified along a single axis or needs complex multi-variable spatial mapping.
Dimensional product – It is the precise specification of size, shape, and geometric tolerances for a part using digital models or drawings. It guides manufacturing and inspection to ensure components fit and function correctly in an assembly.
Dimensional quantity – It is a measurable physical property which can be expressed as a combination of fundamental base dimensions like mass, length, and time, independent of the specific units used to measure it.
Dimensional radius – It is the hyper-radius ‘r’ in a d-dimensional space, where ‘r-square’ is calculated as the sum of the squares of the Cartesian coordinates (x1square + x2-square ———- +xd-square).
Dimensional random vector – It is a vector ‘X = (X1, X2, ———Xn) to the power T’, where each ‘Xi’ is a random variable, representing a collection of random variables in an n-dimensional space. Its joint cumulative distribution function describes the probability associated with an n-dimensional semi-infinite rectangle for the sample point ‘x = (x1, x2 ———xn) to the power T’.
Dimensional range – It is the span, scale, or set of continuous numeric boundaries within a specific coordinate space, data attribute, or physical measurement.
Dimensional ratio – It is also called standard dimension ratio (SDR). It is a mathematical value used in pipeline engineering to describe the geometry and pressure capacity of a pipe. It is calculated by dividing the outside diameter of the pipe by its minimum wall thickness.
Dimensional restoration – It is a repair process used to rebuild worn, corroded, or damaged mechanical components back to their original size and shape. It extends equipment life and avoids the high cost of total replacement.
Dimensional rigid – It refers to a structural configuration which maintains its shape under load, characterized by joints which do not allow relative motion between connected members, applicable in both two-dimensional and three-dimensional frames.
Dimensional set – It refers to a collection of physical or mathematical variables, parameters, or data attributes grouped together by their shared dimensional properties or analytical axes.
Dimensional shape – It is a geometric figure defined by the number of spatial measurements it possesses, such as length, width, or height. Shapes are normally categorized as two-dimensional (flat) or three-dimensional (solid).
Dimensional similarity – It means that a model and a real-life object have the same physical properties and dimensionless numbers. This lets people test small models in laboratories to predict how full-size things like equipments or bridges are going to work.
Dimensional spectrum – It refers to data or physical properties displayed across multiple frequency, spatial, or mathematical axes. It expands a basic single-line scale into a multi-directional grid or cube. This lets people study complex signals, molecules, or spaces in depth.
Dimensional stability – It is the ability of a plastic part to retain the precise shape in which it was moulded, fabricated, or cast.
Dimensional stability test – It evaluates a material’s ability to retain its original size, length, and width when exposed to environmental stressors like heat, moisture, or washing. Results are calculated as a percentage of linear or volumetric change (shrinkage or growth) from the initial dimensions.
Dimensional structure – It refers to an organization of space, data, or physical properties defined by a specific number of independent directions, coordinates, or hierarchical levels. Depending on the field of study, it describes geometric dimensions, data-base layouts, or material nano-architectures.
Dimensional subspace – It is a subset of a vector space which is itself a valid vector space. Its dimension is the exact number of vectors in any of its bases, representing the minimum number of independent directions needed to span it.
Dimensional surface – It is a two-dimensional boundary or outer layer of a three-dimensional object. It possesses length and width but no depth or volume, functioning as a continuous edge or interface separating an object’s interior from its exterior.
Dimensional tolerance – It is the permissible quantity of variation in the size or physical dimension of a manufactured part. It defines the acceptable upper and lower limits for measurements like length, diameter, and angles, ensuring parts function correctly and fit together without raising manufacturing costs.
Dimensional tolerance grades – These grades refer to standardized classifications in manufacturing and engineering which define the allowable variation in a part’s size, such as length, diameter, or thickness. These grades dictate the permitted deviation from a target or nominal dimension, ensuring parts can be manufactured reliably and assembled correctly. For ensuring interchangeable parts and global manufacturing consistency, majority of the industries utilize the International Tolerance (IT) grades system, defined under standards like International Organization for Standardization standard ISO 286. The IT (international tolerance) grade system is the universal standard for specifying these dimensional variations.
Dimensional tolerance limits – These limits define the acceptable, permissible range of variation for a part’s physical dimensions (like thickness, length, or diameter). Since exact sizes are physically impossible to achieve, these limits define the strict boundaries between a functional part and a defective one.
Dimensional variation – It is the difference between the intended nominal measurements of a manufactured part or assembly and its actual physical dimensions. These differences happen because of small changes in materials, machine wear, tool alignment, and environmental factors like temperature.
Dimensional vector – It is a mathematical entity which can be represented as a weighted sum of unit vectors in different dimensions within a vector space. It allows for the decomposition of vectors into simpler building blocks based on a chosen basis set.
Dimensional wave-guide – It refers to a physical or mathematical structure which guides waves (such as electro-magnetic, acoustic, or quantum waves) by restricting their propagation to a specific number of transverse spatial dimensions, allowing free travel along only one main axis.
Dimensional weight – It is also called volumetric weight. It is a pricing method used by shipping carriers. It calculates shipping costs based on the volume and size of a package rather than its actual physical scale. If a box is large but very light, it takes up valuable space in a truck or plane, so the carrier charges for that space instead.
Dimensioning – It is the application of dimensions to a drawing. Dimensioning by referencing from a point, line, or plane has advantages in clarity and simplicity. Such references, known as datums, have selected locations which are fixed and theoretically exact.
Dimensionless axial distance – It is a scaled, unitless ratio comparing a local position along the length of a system (‘z’ or ‘x’) to a characteristic reference length (‘L’ or tube diameter / Peclet number combinations), simplifying fluid flow and heat transfer equations.
Dimensionless constant – It is a fixed numerical value which has no units or physical dimensions like length, mass, or time. Its value never changes, no matter what system of measurement people use.
Dimensionless derivative – It is the rate of change of one dimensionless variable with respect to another dimensionless variable, yielding a pure number free of physical units. It is formed by scaling physical variables using characteristic reference values so that all units cancel out during differentiation.
Dimensionless drainage radius (reD or rDe) – It is a scaled, unitless ratio used in petroleum engineering and hydrogeology to represent the outer boundary or drainage limit of a reservoir relative to the wellbore radius ‘rw’. It is defined as ‘reD = re /rw’, where ’re’ is the drainage radius and ‘rw’ is the well radius.
Dimensionless form – It is a number or mathematical expression which has no physical units like meters or seconds. It is formed by dividing physical values by reference scales, or by taking a ratio of two identical units. This leaves a pure number with a dimension of one.
Dimensionless fracture conductivity – It is a key design number. It compares a fracture’s ability to carry fluids to the wellbore against the surrounding rock’s ability to supply fluids into that fracture.
Dimensionless function – It is a mathematical relation or expression where both the independent input variables and the dependent output values are pure numbers without physical units (like meters, seconds, or kilograms). It maps dimensionless inputs to dimensionless outputs.
Dimensionless governing equation – It is a mathematical model of a physical system where all variables and parameters are scaled into pure, unitless numbers. This transformation is achieved by dividing each dimensional variable by a characteristic reference scale of the system.
Dimensionless group – It is a combination of physical variables which has no units or dimensions. It is equal to one. These groups compare different forces or properties in a system. They help scale up tests from small models to large real-world machines.
Dimensionless number – It is a pure quantity with no physical units (like meters or seconds), normally expressed as a ratio comparing two like forces or properties. Key examples include the Reynolds number, Mach number, and Froude number.
Dimensionless parameter – It is a pure number with no physical units of measurement (like meters or kilograms). It is typically formed by the ratio of comparable physical quantities or competing forces where the units cancel out completely, leaving an invariant value which remains the same regardless of the measurement system used.
Dimensionless product – It is a combination of physical variables multiplied or divided together so that all base dimensions (such as mass, length, and time) cancel out. It results in a pure, unitless number whose value stays the same no matter what measurement system people use.
Dimensionless ratio – It is a quantity which expresses a simple ratio of two dimensionally equal quantities or that of dimensionally equal products of quantities in the numerator and denominator. It encompasses different groups, including physical similarity criteria and dimensionless physical constants.
Dimensionless stream function -It is a scaled, unitless version of the standard fluid stream function. It is used in fluid mechanics and heat transfer to simplify partial differential equations, such as boundary layer equations, into ordinary differential equations by using similarity variables.
Dimensionless temperature – It is a normalized, unitless ratio used in heat transfer and thermodynamics to simplify equations. It scales an actual temperature or temperature difference relative to reference or characteristic temperatures of a system, typically resulting in a value between 0 and 1.
Dimensionless temperature profile – It is a normalized representation of temperature variation within a system (such as a fluid boundary layer or a solid wall), scaled relative to characteristic reference temperatures and lengths to allow generalized comparison and analysis across different operating conditions.
Dimensionless term – It is a pure number which has no physical units like meters, kilograms, or seconds. It happens when units cancel out in a mathematic ratio.
Dimensionless time – It is a scaled, unitless number used to represent time relative to a specific characteristic system time. It is calculated by dividing a real physical time (t) by a characteristic time scale (tc) of the process, such as diffusion or fluid flow time.
Dimensionless unit – It is a number or measurement which has no associated physical dimensions like mass, length, or time. It acts as a pure number, frequently representing a ratio where measurement units cancel out, or a simple count of items.
Dimensionless variable – It is a physical quantity which has no units or dimensions, but can still change or take on different values. It is frequently formed by taking the ratio of similar physical quantities where the units cancel out.
Dimension stone – It is natural rock quarried and cut into specific sizes, shapes, or slabs with designated surface finishes for building, paving, and architectural uses. It contrasts with crushed stone, which is blasted into random rubble for aggregate and road filler.
Dimer – It is a condensation compound formed from two monomers or molecules.
Dimerization – It is the formation of a dimer. It is a chemical process where two smaller molecules, called monomers, join together to form a single larger molecule called a dimer. This combination can happen through strong covalent bonds or weaker non-covalent forces, and the process is frequently reversible.
Dimer acid – It is a di-carboxylic chemical made by joining two unsaturated fatty acid molecules (normally 18-carbon chains like oleic or linoleic acid from tall oil or vegetable oils). It is a clear, yellow, viscous liquid used to make flexible plastics, hot-melt adhesives, and inks.
Di-methacrylates – These are organic monomers containing two reactive methacrylate functional groups. When exposed to free-radical initiators or light, these dual functional groups allow the molecules to form dense, tightly bound 3D cross-linked polymer networks, providing high mechanical strength, chemical resistance, and thermal stability.
Di-methyl di-sulphide – It is also known as methyl di-sulphide. It is an organic chemical compound with the molecular formula CH3SSCH3. It is a colourless, flammable liquid with a pungent, garlic-like odour. It is a compound used in chemistry for locating double bonds through a reaction catalyzed by iodine. It is a di-alkyl di-sulphide, meaning it contains two alkyl groups (in this case, methyl groups) linked by a di-sulphide bond (S-S).
Di-methyl ether (CH3OCH3) – It is the simplest organic ether. It is a colourless, non-toxic gas at room temperature, but liquefies under moderate pressure. It is widely used as a clean-burning diesel alternative fuel, an aerosol propellant, and a chemical solvent.
Di-methyl ether (DME) process – It is an industrial method used to manufacture di-methyl ether (CH3OCH3), a clean-burning synthetic gas utilized as an alternative to diesel and liquefied petroleum gas (LPG). It is produced mainly from feedstocks like natural gas, coal, or biomass through synthesis gas (syngas).
Di-methyl sulphide (DMS) – It is also known as methyl-thio-methane. It is a simple organo-sulphur compound with the chemical formula (CH3)2S. It is a volatile, flammable liquid with a characteristic, frequently unpleasant odour. It is produced by several sources, including marine phytoplankton, bacteria, and as a breakdown product of other compounds. In its applications, it can be a useful chemical for several processes.
Dimple – In porcelain enamel, it is a cone-like depression defect in the fired enamel surface, somewhat larger than a pinhole.
Dimple rupture – It is a fractographic term describing ductile fracture which occurs through the formation and coalescence of micro-voids along the fracture path. The fracture surface of such a ductile fracture appears dimpled when observed at high magnification and normally is very clearly resolved when viewed in a scanning electron microscope (SEM).
Dimpled rupture fracture – It is a ductile fracture which occurs through the formation and coalescence of micro-voids (dimples) along the fracture path. The fracture surface of such a ductile fracture appears dimpled when observed at high magnification and normally is most clearly resolved when viewed in a scanning electron microscope.
Dimpling – It is the stretching of a relatively small, shallow indentation into sheet metal. In aircraft, it is the stretching of metal into a conical flange for a counter-sunk head rivet.
Diode – It is a two-terminal electronic component which conducts current mainly in one direction (asymmetric conductance). It has low (ideally zero) resistance in one direction, and high (ideally infinite) resistance in the other. A diode vacuum tube or thermionic diode is a vacuum tube with two electrodes, a heated cathode and a plate, in which electrons can flow in only one direction, from cathode to plate. A semi-conductor diode, the most commonly used type today, is a crystalline piece of semi-conductor material with a p–n junction connected to two electrical terminals.
Diode array – It is a single electronic chip or package containing multiple diodes. It comes in two main forms namely a general circuit array (used for voltage regulation, switching, or signal protection) or a photodiode array (used in optics to detect light and measure full wave-length spectra at the same time).
Diode bridge – It is an arrangement of four or more diodes connected in a bridge circuit configuration which converts alternating current (AC) into direct current (DC). It provides full-wave rectification by flipping the negative parts of an alternating current wave into positive values, ensuring current flows through the load in only one direction.
Diode characteristic curve – It is a graph which shows how electric current through a diode change when a person changes the voltage across it. It maps voltage on the horizontal axis and current on the vertical axis, proving that a diode does not follow Ohm’s law and only lets current flow in one direction.
Diode-clamped multi-level inverter – It is also called a neutral-point clamped (NPC) inverter. It is a power electronic circuit which changes direct current (DC) into alternating current (AC). It uses series capacitors and clamping diodes to make a stepped, staircase-like voltage wave. This design cuts down power waste and lowers stress on parts in big industrial systems.
Diode laser absorption spectroscopy – It is frequently called tunable diode laser absorption spectroscopy (TDLAS). It is a gas-sensing technique which uses narrow-band semi-conductor laser light to target specific molecular absorption lines. By tuning the laser wave-length and measuring light loss, it calculates trace gas concentrations with high speed and precision.
Diode model – It is a simplified mathematical or electrical equivalent representation used to approximate the non-linear behaviour of a real semi-conductor diode. It allows to analyze and calculate circuit responses without handling complex physical formulas.
Diode-pumped solid-state laser – It is a type of solid-state laser energized by semi-conductor laser diodes instead of traditional flash lamps. The diode light excites a solid gain medium, such as a crystal or glass like Nd:YAG (neodymium-doped yttrium aluminium garnet), to produce an efficient, stable, and high-quality coherent light beam.
Diode turn-on – It is the minimum forward voltage needed to overcome the internal barrier of the semi-conductor junction and allow substantial current to flow.
Diode voltage – It is the electrical potential difference across a diode’s terminals. It determines whether the diode allows current to flow (conductor) or blocks it (insulator) based on the applied polarity.
Di-olefins – These are also known as dienes. These are a class of unsaturated hydro-carbons which contain exactly two carbon-carbon double bonds. Acyclic (open-chain) di-olefins share the general chemical formula CnH(2n-2), They are highly reactive and serve as essential building blocks in the production of synthetic rubber.
Diopter – It is a standard unit of measurement used in optics to define the focusing power or refractive power of a lens. It is equal to the reciprocal of the focal length in meters (D = 1/focal length). Lenses with higher diopter values bend light more sharply.
Diorite – It is an intrusive igneous rock composed mainly of sodic plagioclase, hornblende, biotite or pyroxene.
Dioxins – These are a group of chemical compounds which are persistent organic pollutants (POPs) in the environment. They are mostly by-products of burning or various industrial processes. Some of them are highly toxic, but the toxicity among them varies 30,000-fold. They are grouped together since their mechanism of action is the same.
Dip – It is the angle at which a vein, structure or rock bed is inclined from the horizontal as measured at right angles to the strike.
Dip angle – It is the angle of inclination of a geological feature relative to the horizontal plane. It is distinct from dip direction, which refers to the direction of the downward slope.
Dip brazing – It is a brazing process in which the heat needed is furnished by a molten chemical or metal bath. When a molten chemical bath is used, the bath can act as a flux. When a molten metal bath is used, the bath provides the filler metal.
Dip coat – In the solid mould technique of investment casting, it is an extremely fine ceramic precoat applied as a slurry directly to the surface of the pattern to reproduce maximum surface smoothness. This coating is surrounded by coarser, less expensive, and more permeable investment to form the mould. In the shell mould technique of investment casting, it is an extremely fine ceramic coating called the first coat, applied as a slurry directly to the surface of the pattern for reproducing maximum surface smoothness. The first coat is followed by other dip coats of different viscosity and normally containing different grading of ceramic particles. After each dip, coarser stucco material (Portland cement, sand and water + lime) is applied to the still-wet coating. A build-up of several coats forms an investment shell mould.
Dip coating – It consists of applying a plastic coating by dipping the article to be coated into a tank of melted resin or plastisol, then chilling the adhering metal.
Dip direction – It is the compass bearing (0-degree to 360-degree) pointing down the steepest slope of a tilted rock layer or geological plane. It is always measured perpendicular to the strike (the horizontal line along the tilted surface) and shows which way the layer tilts downward.
Dipentaerythritol – It is a chemical compound, specifically a polyol, which is used in several industrial applications. It is structurally related to pentaerythritol and can be prepared from it. Dipentaerythritol is normally used as an esterification alcohol in the production of polyesters for paint vehicles, as a lubricant, and in several other applications like plastics, coatings, and stabilizers.
Dipentaerythritol esters – These are specialized synthetic polyol esters formed by reacting dipentaerythritol (a complex alcohol) with organic fatty acids. Since their core molecular structure contains six reactive hydroxyl groups, they can form highly stable, hexavalent compounds known for extreme thermal stability, low volatility, and excellent lubricating properties.
Dipentaerythritol polyol esters – These are a class of high-performance synthetic lubricants and chemical additives. They are synthesized through a chemical reaction between dipentaerythritol (an alcohol) and different fatty acids. They are highly valued across industrial, automotive, and aviation sectors for their exceptional thermal stability, oxidative resistance, and low volatility.
Diphase cleaning – It is removing soil by an emulsion which produces two phases in the cleaning tank namely a solvent phase and an aqueous phase. Cleaning is done by both solvent action and emulsification.
Di-phenolic acid – It is an organic compound with the formula C1718O4 and IUPAC (International Union of Pure and Applied Chemistry) name 4,4-bis(4-hydroxyphenyl)pentanoic acid. It is a bisphenol and carboxylic acid created by combining phenol and levulinic acid. It serves as a sustainable, bio-based replacement for bisphenol A (BPA) in high-performance polymers.
Dip lance – It is a lance which is dipped in hot metal for the injection of the desulphurization reagents. Dip-lance method can reliably reduce the sulphur content of the hot metal to figures as low as 0.001 %. It allows the use of several desulphurization reagents, such as lime, calcium carbide and magnesium, which remove the sulphur from the hot metal by chemical reaction and convert it to the slag.
Diplex filter – It is also called diplexer. It is a passive three-port electronic device which uses frequency-selective filters to combine or separate two distinct, non-overlapping frequency bands so they can share a single common transmission line or antenna without interfering.
Dip needle – It is a compass with the needle mounted so as to swing in a vertical plane, used for prospecting to determine the magnetic attraction of rocks.
Dipolar bond – It is a type of covalent bond formed by the coordination of two or more electrically neutral moieties, the combination of which results in a charge-separated molecule or coordination complex, in which two electrons deriving from the same atom are shared between the donor atom and an acceptor atom, creating an internal two-center molecular dipole moment.
Dipolar molecule – It is an electrically neutral molecule which has a positive end and a negative end. These opposite regions form since electrons are shared unevenly across its bonds. Key examples include water, hydrogen fluoride, and ammonia.
Dipolar polarizability – It also called orientational polarizability. It is the measure of how easily permanent electric dipoles in polar molecules align themselves with an external electric field. It describes the reorientation of molecules which already have a built-in separation of positive and negative charges.
Dipole – It is the electric or magnetic separation of electric charge into a pair of charges of equal magnitude but opposite sign, one positively charged and one negatively charged, separated by some typically small distance.
Dipole antenna – Itis the most basic and common type of radio antenna. It has two metal rods or wires. A signal feed line connects to the centre. It turns electric current into radio waves, or radio waves into current. The total length is normally half of the signal wave size.
Dipole field – It is the physical pattern of force created by a pair of equal and opposite charges (or magnetic poles) separated by a short distance. The strength of this field drops off much faster with distance (1/r-cube) than the field of a single point charge (1/r-square).
Dipole-induced di-pole forces – These are weak van der Waals forces where a molecule with a permanent dipole distorts the electron cloud of a neutral, non-polar molecule induced dipole. This creates a temporary dipole. In extractive metallurgy, this controls gas solubility and slag-metal interactions, while in physical metallurgy, it helps model how localized polar impurities bind to non-polar metal lattices.
Dipole interactions – These refer to the interactions which occur between two permanent molecular dipoles, characterized by their dipole moments. These interactions are influenced by temperature, as thermal forces can counteract the electrostatic orienting forces between the dipoles.
Dipole moment – It measures how positive and negative charges separate in a system or molecule. It shows the polarity of a chemical bond or an entire molecule. It equals the size of the charge multiplied by the distance between the charges.
Dipole source – It is a model of a physical field created by two equal and opposite point sources (mono-poles) placed a very small distance apart and operating completely out of phase. It produces a directional field rather than an equal spread in all directions.
Dipole strength – It is normally quantified as the dipole moment. It measures the magnitude of polarity or the intensity of a system’s positive and negative charge separation. It equals the product of the charge magnitude and the distance separating the charges.
Dipped fabric – It is a fabric coated with rubber compound by passing through a rubber solution and drying.
Dipped joint – It refers to a thin, tight joint created by dipping refractory bricks into a very thin liquid mortar. This technique is used to lay the brick linings in melting furnaces and ladles, ensuring minimal mortar thickness for better structural integrity and thermal efficiency. In structural geology, a dip joint is a natural fracture or crack in a rock mass where the fracture plane runs parallel to the dip direction (the steepest angle of inclination) of the surrounding rock strata.
Dip-pen nano-lithography – It is a direct-write scanning probe nano-fabrication technique where an atomic force microscope (AFM) tip acts as a ‘pen to transfer molecules (ink) onto a solid substrate through a capillary water meniscus. It enables precise chemical and material patterning down to 15-nan-meter resolutions.
Dipping – In porcelain enameling, it is the process of coating a metal shape by immersion in slip, removal, and draining. In dry process enameling, it is the method of coating by immersing the heated metal shape for a short time in powdered frit.
Dip plating – It is depositing a metallic coating on a metal immersed in a liquid solution, without the aid of an external electric current.
Diprotic acid – It is an acid capable of donating two protons (hydrogen ions, H+) per molecule in an aqueous solution. These acids donate their protons in two sequential steps rather than all at once.
Dip soldering – It is a soldering process in which the heat needed is furnished by a molten metal bath which provides the solder filler metal.
Dipstick – It is a thin metal rod or plastic strip used to measure the level of a liquid inside a container. It is a simple measuring device consisting of a metal bar with an etched scale, used to approximate the liquid level in shallow vessels by being removed and read by a human operator.
Dip tank – It is a container filled with liquid (normally other than plain water. It is used to immerse objects for coating, finishing, cleaning, or treating. Dip tanks are widely used in industrial and agricultural settings for applications like painting, and electroplating.
Dip tube – Extending the blow-down valve on large gate valves needs a tube which is located inside of the valve. This tube is called the dip tube and extends through the bonnet to the bottom of the body cavity.
Di-pyramid – It refers to a 3D geometric crystal habit where two pyramids are placed symmetrically base-to-base. Specifically, it is a closed form crystal shape where faces above and below a horizontal equatorial mirror plane perfectly mirror each other. Di-pyramids are classified as per their cross-sectional base and symmetry. A typical di-pyramid possesses 2n faces and can exist in different crystal systems namely (i) tetragonal di-pyramids which feature an 8-faced form consisting of two 4-sided pyramids base-to-base, (ii) hexagonal di-pyramids which consist of a 12-faced form created by two 6-sided pyramids placed base-to-base, and (iii) orthorhombic di-pyramids which are closed forms of 8 faces.
Dirac constant – It is by h-bar. It is the reduced Planck constant, defined as Planck’s constant (h) divided by 2-pi (h-bar = h}/2-pi). It equals around 1.05457 x 10 to the power -34} joules and sets the fundamental scale for angular momentum and action in quantum systems.
Dirac delta function – It is a generalized function defined as zero everywhere except at zero where it is infinite, satisfying the core properties of unit total integral and the sifting property. It a mathematical function which has a non-zero value only at a specific point, while its area is 1 and height is infinite. It is particularly useful for assigning a value to a function at given points, exemplified by its sifting property in integration.
Dirac measure – It is a mathematical assignment of mass or probability which concentrates an entire unit of value (1) at a single, specific point x0 in a space and zero everywhere else. It is the rigorous measure-theoretic foundation behind the informal Dirac delta function or unit impulse.
Dirac notation – It is a standard mathematical shorthand to describe linear states, vectors, and operators in complex vector spaces without relying on specific coordinate systems.
Direct ablation – It is a precision manufacturing process where high-fluence ultra-violet or pulsed laser energy strikes a solid surface, causing rapid localized vapourization or sublimation to etch material cleanly. It removes targeted layers instantly without masks, photoresists, or substantial thermal damage to surrounding areas.
Direct absorption receiver – It is a solar thermal technology where the working heat transfer fluid directly absorbs concentrated solar radiation. This eliminates intermediate solid absorber walls, opaque metal tubes, or surface coatings used in conventional systems.
Direct actuation – It means a control signal or energy source moves a mechanical component or valve directly without using intermediate pilot systems, fluid amplifiers, or complex gear linkages. The input force translates into an immediate proportional output movement.
Direct-age forged – It is a specialized manufacturing technique where the superalloy IN-718 (Inconel 718) is hot-worked to precise dimensions and then aged directly for precipitation hardening, completely skipping the conventional, energy-intensive solution annealing step.
Direct alcohol fuel cells – These cells are electro-chemical devices which convert the chemical energy of liquid alcohol fuels (like methanol or ethanol) directly into electricity. They eliminate the need for an external fuel reformer, offering high energy density and easy liquid fuel storage for portable and mobile power applications.
Direct alcohol fuel cells (DAFCs) performance – It measures how effectively an electro-chemical system converts liquid alcohol chemical energy into electrical power. Key metrics include power density, conversion efficiency, and durability, constrained by sluggish anode kinetics and fuel crossover.
Direct ammonia fuel cell – It is an electro-chemical energy conversion device which feeds liquid or gaseous ammonia (NH3) directly into the anode to generate electricity. It bypasses the need for an external ammonia-cracking reactor by electro-chemically oxidizing ammonia to release nitrogen and water (or hydrogen ions), achieving high energy density without direct carbon emissions.
Direct analogs – These are physical systems or electrical circuits used to replicate and study the continuous behaviour of another separate system by matching their shared mathematical differential equations.
Direct-arc furnace – It is an industrial melting furnace where an electric arc is struck directly between carbon / graphite electrodes and the conductive charge (normally metal scrap). The charge itself acts as an electrical pole, forcing the arc current to flow through the material for rapid heating and refining.
Direct-bonded basic brick – It is a fired refractory in which the grains are joined predominantly by a solid-state diffusion mechanism.
Direct bonding – It is also called fusion bonding. It is a glueless technique which joins two clean, ultra-flat surfaces together without using intermediate adhesives, filler metals, or external clamping forces. The materials adhere spontaneously at room temperature through molecular forces and are frequently heated later to form permanent covalent bonds.
Direct carbonation – It is a single-step chemical process where carbon di-oxide (CO2) reacts directly with metal-bearing minerals, industrial waste, or alkaline materials in one single reactor to form stable solid carbonates. It contrasts with indirect methods which split mineral extraction and carbonation into separate stages.
Direct casting – It is a batch process where molten metal is poured directly into an independent, custom-shaped mould to solidify. It allows for highly intricate part geometries, unique alloy material properties, and is ideal for low-volume or custom production runs.
Direct chill casting – It is a continuous method of making ingots for rolling or extrusion by pouring the metal into a short mould. The base of the mould is a platform which is gradually lowered while the metal solidifies, the frozen shell of metal acting as a retainer for the liquid metal below the wall of the mould. The ingot is normally cooled by the impingement of water directly on the mould or on the walls of the solid metal as it is lowered. The length of the ingot is limited by the depth to which the platform can be lowered. Hence, it is frequently being called semi-continuous casting.
Direct circulation system – It is a thermal or fluid set-up where the working fluid or potable water flows directly through the main heat source or collectors without an intermediate heat exchanger. It is widely used in solar thermal water heating and drilling fluid transport.
Direct coal liquefaction – It is a process which converts solid coal into synthetic liquid hydro-carbons (syn-crude) by breaking down its complex organic structure and adding hydrogen at high temperatures and pressures, completely bypassing intermediate gasification.
Direct cold extrusion – It is a manufacturing process where a metal billet at room temperature is forced by a punch or ram through a stationary die. Since the ram and the extruded material move in the same direction, it produces solid or hollow shapes with improved strength and precise dimensions.
Direct compression moulding – It is also known as net-shape compression moulding. It is a process where a precise measure of polymer powder or resin is compressed and sintered directly inside an individual mould cavity using high heat and pressure to create a finished or near-net-shape part without intermediate cutting.
Direct contact – It mainly refers to electrical safety where a person touches a live, uninsulated conductor or part under voltage. It can also describe thermal or mechanical interactions where two physical bodies or fluid streams touch directly without an intermediate wall or barrier.
Direct contact evaporation – It is a thermal process where a hot gas or immiscible working fluid transfers heat directly to a liquid by physically mixing with it, eliminating any solid separating wall to vapourize the solvent or fluid.
Direct contact membrane distillation – It is a thermally driven separation process where a heated liquid feed and a cool permeate (distillate) directly contact opposite sides of a microporous hydrophobic membrane. The temperature difference creates a vapour pressure gradient, forcing volatile molecules (like water) to evaporate, pass through the pores as vapour, and condense inside the module. Direct contact membrane distillation (DCMD) relies on four specific mechanisms to separate volatile solvents from non-volatile solutes namely temperature gradient, vapourization, vapour transport and direct condensation.
Direct conversion – It normally means changing one form of energy or signal into another without using intermediate steps like mechanical movement, heat cycles, or middle frequencies.
Direct conversion receiver – It is a radio architecture which demodulates incoming radio frequency (RF) signals directly to baseband audio or data frequencies in a single step. It eliminates intermediate frequency (IF) hardware stages and image-reject filters used in superheterodyne designs.
Direct cooling – It is a thermal management process where a cooling medium (like a refrigerant, water, or air) makes uninhibited physical contact with or flows directly inside the target component to absorb heat, bypassing intermediate heat exchangers.
Direct cooling system – It is a thermal management set-up where the working cooling medium (such as a refrigerant, chilled fluid, or raw water) makes direct physical contact with, or flows directly through, the target component or space being cooled without passing through an intermediate heat exchanger.
Direct correlation function – It is a fundamental measure in statistical mechanics and liquid-state physics. It quantifies the direct, unmediated spatial or temporal dependence between two particles or variables, isolating direct interactions from indirect effects transmitted through intermediate particles.
Direct costs – These are the costs which can be directly assigned to each type of material or activity at the time of its occurrence, i.e., it is connected directly to each type of good or cost function. The direct costs of a process can be easily identified and quantified from necessary resources to carry out the process activities. These costs are directly attributed to the work of the process and hence do not need apportionment to be allocated to the process. Direct costs are directly attributable or traceable to cost object.
Direct current – It is one-directional flow of electric charge. An electro-chemical cell is a main example of DC (direct current) power. Direct current can flow through a conductor such as a wire, but can also flow through semi-conductors, insulators, or even through a vacuum as in electron or ion beams.
Direct current circuit breaker – It is a specialized protective switch which automatically stops direct current flow during an overload or short circuit. Unlike alternating current, DC (direct current) does not drop to zero voltage naturally, so these breakers use special magnets and wider gaps to put out electrical sparks.
Direct current cleaning – It is electrolytic cleaning in which the work is the cathode.
Direct current electric arc furnace – It is an electric arc furnace in which a single electrode positioned at the centre of the furnace roof is the cathode of the system. Current passes from the electrode through the charge or bath to a cathode located at the bottom of the furnace. Current from the bottom of the furnace then passes through the furnace refractories to a copper base plate to outside cables. It is used in the production of ferroalloys, carbon and alloy steels, and stainless steels. Direct current arc furnaces represent a different concept in arc furnace design. Reduced electrode consumption of the order of 50 % to 60 % is the major benefit of a direct current arc furnace compared to a conventional three phase arc furnace. Noise levels for the direct current arc furnaces are lower. Lower maintenance costs are claimed and refractory costs are less for sidewall but more for the furnace bottom. A direct current arc furnace needs an addition of the bottom electrode (anode), a direct current reactor, and a thyristor all of which add cost to a direct current arc furnace. Direct current arc furnaces apart from their low energy and electrode consumption ensure excellent thermal and metallurgical homogenization of the liquid steel. Also, there is the increased stirring effect of the direct current arc that supports this process. Compared to alternating current electric arc furnaces, direct current arc furnaces cause fewer network disturbances and hence can be connected even to the weak electric grids.
Direct current electrode negative – It is the arrangement of direct current arc welding leads in which the work is the positive pole and the electrode is the negative pole of the welding arc. It is also referred to as straight polarity.
Direct current electrode positive – It is the arrangement of direct current arc welding leads in which the work is the negative pole and the electrode is the positive pole of the welding arc. It is also referred to as reverse polarity.
Direct current motor – It is an electro-mechanical energy conversion device which transforms direct current electrical power into mechanical rotation using the interaction of magnetic fields and current-carrying conductors.
Direct current resistance – It is the ohmic resistance of a conductor which is directly dependent on the conductor material, the conductor gauge and the length of the conductor. A precise measurement of the direct current resistance is possible with a micro-ohmmeter.
Direct current reverse polarity – In arc welding, it occurs when electrode is connected with positive terminal of the welding power source (direct current type) and base metals are connected with the negative terminal.
Direct current straight polarity – In arc welding, it occurs when the plates are positive and the electrode is negative, causing the electrons to go from the electrode tip to the base plates.
Direct detection system – It refers to an intensity-modulation / direct-detection (IM / DD) architecture where an optical receiver uses a single photo-detector to directly convert incoming light wave power variations into an electrical signal, ignoring phase and frequency.
Direct digital manufacturing – It is a production process where physical end-use parts are fabricated directly from digital computer-aided design (CAD) models. By relying mainly on additive manufacturing or 3D printing, direct digital manufacturing (DDM) completely bypasses the need for traditional hard tooling like moulds or dies. In product development, this work-flow completely reimagines how goods are designed, prototyped, and brought to market.
Direct digital synthesis – It is an electronic technique used to generate precise analog wave-forms, such as sine, square, or triangle waves, from a digital data stream and a single fixed-frequency reference clock. It provides fast frequency switching, fine tuning resolution, and digital control over phase and amplitude.
Direct digital synthesizer – It is an electronic system used to generate arbitrary analog wave-forms, very frequently a sine wave, from a single, fixed-frequency reference clock using digital data processing blocks. It provides precise frequency and phase tuning without relying on traditional analog oscillator circuits.
Direct digitization – It is the process of converting low-level analog signals from sensors or transducers directly into a digital format early in the signal chain, bypassing traditional intermediate analog conditioning like DC (direct current) amplification or filtering.
Direct drive mechanism – It connects a motor directly to a load or device without using intermediate transmission components like gear-boxes, belts, or pulleys. This provides faster response times, higher mechanical precision, lower maintenance, and quieter operation by entirely eliminating mechanical wear and backlash.
Direct drive motor – It is an electric motor which powers a device directly without using intermediate transmission parts like gear-boxes, belts, or pulleys. Since the motor connects straight to the load, it reduces energy loss, minimizes maintenance needs, and offers highly precise, quiet operation.
Direct-driven hydraulic presses – These presses feature a system where variable-speed electric servo motors and drives directly control the hydraulic pumps, eliminating the need for flow control valves or accumulators. This provides high-precision, highly repeatable force and stroke control for metal forming, powder compacting, and forging operations.
Direct-drive press – It is a machine where the motor is connected directly to the pressing mechanism (like a screw, ram, or crank) without intermediate mechanical parts like gears, belts, or flywheels. This configuration eliminates energy loss, reduces maintenance, and provides precise, dynamic control over the pressing stroke.
Direct drive system – It connects a motor directly to the driven load, eliminating intermediate mechanical components like gear-boxes, belts, and pulleys. This one-to-one coupling transfers torque without mechanical losses, considerably improving precision, responsiveness, and reliability by eliminating backlash and friction.
Direct drive transmission – It connects the motor or engine directly to the load without any intermediate speed reducers, belts, or gear trains. This means the output shaft spins at the exact same rotational speed and torque as the motor, eliminating power loss and wear associated with mechanical linkages.
Direct energy conversion – It is the process of changing one form of energy directly into electrical energy without any intermediate mechanical or thermal stages, such as turning a turbine or using a steam cycle.
Directed energy deposition – It is an advanced printing technique used for repairing or adding material to existing components, utilizing focused thermal energy to fuse wire or powder feedstock as it is deposited. This method allows for fine-grain structural control and can incorporate metals, ceramics, and polymers in the construction of layers.
Directed light fabrication – It is an advanced additive manufacturing (3D printing) technique which fuses metal powder delivered through gas into the focal zone of a high-powered laser beam. Guided by computer models, it builds fully dense, near-net-shape metal parts layer by layer.
Directed movement – It is also called goal-directed movement. It is a planned, controlled shift of a system, robotic limb, or mechanism toward a specific spatial target or coordinate. It needs both path planning and real-time execution feedback to minimize error and achieve the desired task.
Direct-electric drive press – It is an electro-mechanical machine which uses a brushless electric motor (typically a high-torque servo motor) coupled directly to the press’s drive mechanism, eliminating intermediate gears, belts, or hydraulic fluids. It converts electrical energy into precise, linear pressing or bending force.
Direct electron transfer – It is a process where electrons move directly between an electrode surface and a biological or chemical redox centre without needing chemical shuttles or redox mediators.
Direct energy conversion – It is the process of changing one form of energy directly into electrical energy without intermediate mechanical steps or thermal cycles. By bypassing turbines, generators, and combustion steam loops, direct energy conversion (DEC) systems avoid traditional thermodynamic limits and mechanical friction losses.
Direct energy deposition – It is an advanced metal additive manufacturing process which melts and fuses material, typically wire or powder, using a focused energy source (e.g., laser, electron beam, or electric arc) as it is deposited. It is mainly used to build new large-scale components or repair high-value, worn parts.
Direct evacuation system – It is installed in electric arc furnace for the evacuation of the exhaust gases. It is installed so that the furnace operators can better see what is happening in and around the furnace. Majority of the modern electric arc furnace shops now use a ‘fourth hole’ direct furnace shell evacuation system. The term fourth hole refers to an additional hole other than those for the electrodes, which is provided for exhaust gas extraction. On direct current furnaces with only one electrode, the fume extraction port is sometimes referred to as the ‘second hole’. It is important to maintain sufficient draft on the furnace for the several reasons namely (i) to provide adequate pollution control, (ii) excessive shop emissions make it difficult for the crane operator to charge the furnace, (ii) excessive emissions around the electrode ports can result in damage of hoses, cables, the electrode holder, the furnace delta, roof refractory, accelerated electrode wear, and damage to the electrode spray cooler etc., (iv) emissions at the roof ring can result in warping of the roof ring structure, (v) excessive emissions of carbon mono-oxide to the secondary canopy system can result in explosions in the ductwork downstream, and (vi) excessive dust build-up can cause arcing between electrode phases. Majority of the direct evacuation systems consist of water-cooled duct, spray cooling, dry duct and may or may not have a dedicated direct evacuation system booster fan.
Direct evaluation – It means assessing a system or product by directly measuring actual performance, or physical behaviour against set criteria, rather than relying on indirect opinions or surveys. It uses hard data from tests, experiments, and observations.
Direct extrusion – It is also called forward extrusion. It is the extrusion process in which a preheated billet is placed in the container and is pushed by the ram through the stationary die to form the extruded section. It is the conversion of an ingot or billet into lengths of uniform cross section by forcing metal to flow plastically through a die orifice. In forward (direct) extrusion, the die and ram are at opposite ends of the extrusion stock, and the material flows in the exact same direction as the ram’s movement, creating long continuous shapes with a uniform cross-section. Also, there is relative motion between the extrusion stock and the die.
Direct extrusion press – It is a machine which forces a preheated metal billet through a stationary die using a hydraulically driven ram. Since the metal flows in the exact same forward direction as the moving ram, the process is also widely known as ‘forward extrusion’.
Direct extrusion process – It is a metal-forming process where a raw material, or billet, is placed into a stationary container and forced through a fixed die by a hydraulic ram or screw. The material flows in the same direction as the ram’s movement.
Direct filtration – It is a water treatment process which passes raw water through a filter medium to remove suspended solids without a preliminary sedimentation or settling step. It frequently includes rapid mixing and coagulation (or brief flocculation), but skips the large clarifying tanks used in conventional treatment.
Direct fire – It is a method of maturing porcelain enamel so that the products of combustion come in contact with the ware.
Direct-fired furnace – It is a heating system where process fluids inside internal tubes or target materials are exposed directly to hot combustion gases and radiant heat from an open burner flame, with no intermediate heat exchanger separating the flame from the working medium.
Direct-fired tunnel-type furnace – It is a continuous-type furnace where the work is conveyed through a tunnel-type heating zone, and the parts are hung on hooks or fixtures to minimize distortion.
Direct force measurement – It is a method where an unknown force is quantified by directly comparing it against a known gravitational force on a standard mass or by placing a dedicated load sensor in the main load-bearing path to yield an immediate mechanical or electrical response.
Direct gasoline injection system – It is an internal combustion engine technology which injects pressurized fuel directly into the main combustion chamber of each cylinder rather than into the intake manifold. This precise delivery optimizes air-fuel mixing, increases thermal efficiency, and improves power output.
Direct injection – It is a fuel delivery system in internal combustion engines where fuel is sprayed directly into the main combustion chamber or cylinder, rather than mixing with air in the intake manifold before-hand. This precise control increases fuel efficiency and power output.
Direct injection technology – It is a fuel delivery method in internal combustion engines where fuel is sprayed at high pressure directly into the engine’s combustion chamber instead of the intake manifold. This allows for precise control over timing and mixture, improving fuel efficiency and power output.
Direct interspecies electron transfer – It is a metabolic process where free electrons pass directly from one microbial cell to another without chemical shuttle molecules like hydrogen or formate. In environmental engineering, direct interspecies electron transfer (DIET) is optimized to accelerate anaerobic digestion, boost methane gas production, and treat wastewater more efficiently.
Direct heating – It is a process where the heating medium or combustion gases physically mix with or directly touch the material being heated, allowing for immediate and rapid heat transfer without a partition wall or heat exchanger.
Direct heating method – It is a process where the heat source, such as combustion gases, a chemical flame, or an electrical current, comes into direct physical contact with, or is generated directly inside, the material being heated. This eliminates intermediate heat exchangers or barrier walls for faster thermal transfer.
Direct heating system – It is a set-up where heat energy is generated right at the target location or where the heating medium mixes directly with the substance being heated, eliminating intermediate heat exchangers or secondary transport loops.
Direct heat reduction – It is also called direct reduction. It is a solid-state process that extracts metallic iron from iron ore by removing oxygen at temperatures below the melting point of iron (typically around 950 deg C to 1,050 deg C). Unlike traditional blast furnaces which melt the ore into liquid pig iron, direct reduction leaves the waste rock (gangue) inside the resulting porous, spongy product known as direct-reduced iron (DRI) or sponge iron.
Direct hot extrusion – It is a metal forming process where a heated metal billet is forced through a shaped die. The ram and the extruded material move in the same forward direction. The billet is heated above its recrystallization point, typically between 50 % to 75 % of its melting temperature, reducing the force needed to shape it.
Direct hot extrusion with lubrication – It is a manufacturing process where a heated metal billet (above its recrystallization temperature) is forced through a die by a ram. The material and ram move in the same forward direction. Lubricants are specifically applied to reduce the severe friction between the billet and the container walls.
Direct hot extrusion with lubrication for steel – It is a metal-forming process where a preheated steel billet is forced through a die by a ram moving in the same direction. Molten glass is typically used as a lubricant to protect the tooling and reduce friction between the billet and the container walls.
Direct hot extrusion without lubrication – It is a metal-forming process where a heated billet is pushed by a ram through a stationary die in the same direction. No external lubricants are applied, meaning the metal slides directly against the container walls, creating high friction and needing higher pressure.
Direct hot extrusion without lubrication and shell for aluminum alloys – It refers to the standard, highly pressurized, forward-moving extrusion process. In this setup, a heated aluminum billet is placed in the container and pushed through a stationary die by a ram. Since no external lubricants or surface-protecting ‘shells’ (such as copper cladding) are used, the billet is crushed directly against the container and die, resulting in metal deformation and high friction.
Direct hot extrusion without lubrication and with a shell – It is frequently called the Sejournet process for steel, though mainly used for copper alloys. It is a hot working process where a heated billet is pushed through a die by a ram. Instead of using external lubricants, the billet’s outer shell is deliberately sacrificed to act as the main friction and heat barrier.
Direct hot pressing – It is also known as uniaxial hot pressing. It is a manufacturing process which consolidates raw powder into a solid, near-theoretical density component by simultaneously applying high heat and unidirectional mechanical pressure. It combines compacting and sintering into a single step, typically using a high-temperature graphite die.
Direct hot quench – It is frequently used in press hardening or hot stamping. It is an advanced metallurgical process where a heated metal component is rapidly cooled while pressed inside pre-conditioned, colder forming tools. This simultaneous shaping and quenching transform the metal into a highly durable, martensitic structure.
Direct hot tube extrusion – It is a manufacturing process where a heated metal billet is forced through a die to create a hollow tube. The ram and the extruded metal move in the same direction, meaning the metal slides against the container wall, needing high pressure to overcome the resulting friction.
Direct injection burner – It is a burner used in flame emission and atomic absorption spectroscopy in which the fuel and oxidizing gases emerge from separate ports and are mixed in the flame itself. One of the gases, normally the oxidant, is used for nebulizing the sample at the tip of the burner.
Direct injection diesel engine – It is an internal combustion system where fuel is injected at ultra-high pressure straight into the main cylinder’s combustion chamber, rather than into a pre-chamber. This design optimizes air-fuel mixing, increases thermal efficiency, and reduces emissions.
Direct injection engine – It is an internal combustion system where fuel is injected through high-pressure valves directly into the main combustion chamber of each cylinder, rather than mixing with air in the intake manifold. This precise delivery allows for superior thermal efficiency, charge cooling, and power output.
Direct injection fuel system – It is an internal combustion engine design where fuel is injected at high pressure (frequently 3.5 mega-pascals to 21 mega-pascals) as a fine mist directly into the main combustion chamber of each cylinder, rather than into the intake manifold.
Directional – It means relating to, indicating, or pointing toward a specific spatial path, course, or goal. It can also describe tools, audio equipment, or signals which focus energy or reception in one particular path rather than scattering it everywhere.
Directional channel – It is a propagation path model which characterizes how radio signals travel in specific spatial angles (such as angle of arrival and angle of departure) rather than uniformly in all directions.
Directional conclusion – It is a conclusion in a two-tailed test which uses the nature of the sample results to suggest where the true parameter lies in relation to the null hypothesized value.
Directional control valves – These valves determine the path through which a fluid traverses a given circuit. For example, they establish the direction of motion of a hydraulic cylinder or motor. This control of the fluid path is accomplished primarily by check valves, shuttle valves, and two-way, three-way, and four-way directional control valves. Directional control valves can be classified in four ways namely (i) type of construction (poppet valves, and spool), (ii) number of ports (two-way valves, three-way valves, and four-way valves), (iii) number of switching position (two position, and three position), and (iv) actuating mechanism (manual actuation. mechanical actuation, solenoid actuation, hydraulic actuation, pneumatic actuation, and indirect actuation).
Directional cosines – It refer to the cosines of the angles between a vector and the axes of a reference coordinate frame, representing the projections of a unit vector along those axes. They are important in defining the orientation of a rigid body in three-dimensional space.
Directional coupler – It is a passive four-port microwave or radio frequency (RF) device which safely samples a fixed, proportional quantity of power from a transmission line while letting the main signal pass through with minimal loss. It is uniquely sensitive to the direction of power flow.
Directional derivative – It measures the instantaneous rate of change of a multivariable scalar field (like temperature or pressure) at a specific point in the direction of an arbitrary unit vector. It generalizes standard partial derivatives beyond the primary coordinate axes.
Directional drilling – It is a method of drilling involving the use of stabilizers and wedges to direct the orientation of the hole.
Directional dynamic – It is an interdisciplinary approach used to analyze, update, and manage how systems, criteria, or physical behaviours change and adapt along specific trajectories over time. It combines vector-based tracking with real-time operational feedback to keep design parameters flexible and accurate.
Directional information – It is the real-time measurement of azimuth and inclination, typically got through accelerometers and magnetometers, which is important to control the direction of a well and improve the effectiveness of directional drilling operations.
Directionality – It refers to a material whose properties, such as strength, electrical conductivity, or magnetic response, vary depending on the direction in which they are measured. This characteristic is also normally known as anisotropy.
Directionally solidified (DS) eutectic composite – It is a metal-matrix composite material produced by directional solidification of the eutectic composition of an alloy.
Directional node – It refers to a network node equipped with a steerable directional antenna which has high gain toward a specific direction, which improves energy efficiency and reduces interference during data transmission. This type of node can adjust the antenna’s direction electronically, allowing for targeted communication with other nodes while minimizing unnecessary engagement with nearby nodes.
Directional property – It is the property whose magnitude varies depending on the relation of the test axis to a specific direction within the metal. The variation results from preferred orientation or from fibering of constituents or inclusions. It consists of deformation by cold working causes changes to the grain structure and, sometimes, variations in mechanical properties across and along a work-piece. Properties measured along the direction of deformation are described as longitudinal, whilst those measured at a right angle to the direction of working are called transverse.
Directional solidification – It is the controlled solidification of molten metal in a casting so as to provide feed metal to the solidifying front of the casting. It is defined as the process in which the casting cools and solidifies progressively from thin sections to heavy sections with constant metal feed into the heavy sections. It is solidification which occurs from farthest end of the casting and works its way towards the sprue. Normally this results in the metal solidifying in a preferred direction. In the limit, the solidification can be controlled to grow as a single grain (single crystal casting).
Directional spreading – It describes how surface wave energy distributes across different angles of propagation relative to a main or mean wave direction. Instead of all waves moving in a single straight line, real ocean waves fan out, meaning energy travels in a spread of directions.
Directional stability – It is a vehicle’s ability to recover its forward heading and resist unwanted turning (yaw) around its vertical axis after a disturbance like a side gust. Also called weather-cock stability, it forces an aircraft to naturally realign with the relative wind.
Directional static stability – It is an aircraft’s initial tendency to create a restoring yawing moment which aligns its nose back into the relative wind after a side-slip or yawing disturbance. Also called weather-cock stability, it acts around the vertical z-axis.
Directional stiffness – It refers to a material or structure’s resistance to deformation (bending, stretching, or twisting) when a load is applied in a specific direction. Since materials and complex geometries frequently have different properties along different axes, their stiffness varies depending on the angle of the applied force.
Directional vector – It is a geometric representation which defines the specific orientation or line of action of a physical quantity (like force or velocity) in 2D or 3D space. It typically takes the form of a unit vector with a magnitude of exactly one, pointing along a designated path or coordinate axis.
Directional vibration – It refers to oscillatory mechanical motion constrained to a specific spatial orientation or axis (such as linear, vertical, horizontal, or rotational) rather than random or omni-directional movement. It is intentionally applied in conveyors and feeders or analyzed to prevent structural failure.
Direction cosine – It is the cosine of the angle between a three-dimensional vector and the positive ‘x’, ‘y’, and ‘z’ coordinate axes. They define the exact orientation of a vector or a rigid body in 3D space.
Direction cosine matrix – It is a 3 × 3 orthogonal matrix used to define the orientation of a moving or rotated coordinate system relative to a reference frame, and to transform vector components between them. Each entry in the matrix is the cosine of the angle between an axis of one coordinate system and an axis of the other.
Direction of arrival – It is the angle or spatial direction of a propagating wave, such as radio, acoustic, or electro-magnetic signals, arriving at a receiver antenna or sensor array.
Direction of arrival (DOA) estimation – It is the signal-processing technique used to determine the spatial angle or bearing from which a propagating wave (such as radio, acoustic, or electro-magnetic waves) arrives at a multi-element sensor array. It relies on measuring the small-time delays or phase shifts of the signal across the different antennas or microphones.
Direction of grain – It refers to the alignment of a material’s internal crystalline structure (in metals) or fibres (in wood and composites).
Direction of grain flow – It refers to the directional alignment and elongation of a metal’s internal crystalline grains, caused by plastic deformation during hot or cold working. As the metal is pressed or hammered into shape, its grains reorganize to follow the contours of the part, creating a fibre-like structure.
Direction of loading – It refers to the orientation and path of external forces acting on the component. Understanding how it interacts with the direction of grain is important for predicting a material’s mechanical strength, ductility, and fatigue resistance.
Direction of ram – It refers to the orientation of the mechanical punch or piston which applies force to shape or process metals (normally in extrusion or forging). The movement of this ram relative to the metal flow defines the type of forming process.
Direction perpendicular – It refers to an orientation which is at a right angle to another direction, as illustrated by the alignment of BaFe (barium ferrite) particles in tape-A, which improves the squareness ratio and performance when compared to randomly oriented particles in tape-B.
Direct iron ore smelting process – It is a smelting reduction process for the production of hot metal. It is a two-stage process. It uses non-coking coal in a powder or granular form to smelt iron ore fines into liquid iron and hence, there is no necessity of a coke ovens plant and a sintering plant. The ore fines are pre-reduced in a fluidized bed furnace and are charged in the smelting reduction furnace along with non-coking coal and fluxes. Oxygen is blown into the smelting reduction furnace. The two stages of the direct iron ore smelting (DIOS) process consist of (i) pre reduction of iron ore in preliminary reduction furnace (PRF), and (ii) the final reduction and melting in the smelting reduction furnace (SRF). The pre reduction of the ore is carried out in two steps utilizing the exhaust gas from the smelting reduction furnace. Each of the steps uses a fluidized bed reactor which is designed as a vertical furnace.
Direct irradiance – It is frequently called direct normal irradiance (DNI) or beam radiation. It is the solar power received per unit area from the sun’s direct disk on a surface held perpendicular to the sun’s rays, excluding scattered or diffuse atmospheric light. It is measured in watts per square meter.
Directivity – It measures how well a device focuses energy or sound in a specific direction compared to an average or omni-directional source. For antennas, it is the ratio of maximum radiation intensity to the average intensity of an isotropic radiator.
Directivity factor – It is the ratio of sound intensity in a specific direction to the average intensity produced by a uniform point source radiating the same total acoustic power. It measures how much a source focuses energy instead of spreading it evenly.
Directivity gain – It takes directivity and adds internal electrical and thermal losses. It measures how well an antenna focuses power compared to total power actually radiated. It compares peak power direction to the total power fed into the antenna from the source. It includes internal losses.
Directivity index – It is a logarithmic measure, expressed in decibels (dB), of how much a sound source focuses its energy in a specific direction compared to an omni-directional source radiating the same total power.
Direct laser writing (DLW) method – It is a maskless, non-contact micro-fabrication process. It uses a tightly focused laser beam to trace and define patterns directly onto a photo-sensitive or target material through computer control. This technique allows engineers to build complex two-dimensional and three-dimensional micro- and nano-structures with high spatial precision.
Direct load control – It is a demand-side management technique. An electric utility or third-party operator directly shuts down or cycles power to consumer equipment, such as air conditioners or water heaters, during peak energy demand events to stabilize the power grid.
Direct lubrication – It is a method where a lubricant (normally oil) is fed right to the specific high-load or high-temperature area of a component, such as the leading edge of a bearing pad, bypassing general or flooded mixing to lower power loss and reduce operating heat.
Directly affected people or areas – These are the people or areas whose interests are affected or potentially affected by certain organizational activities.
Direct measuring instrument – It converts the energy of the measurement directly into energy which actuates the instruments and the value of the unknown quantity is measured or displayed or recorded directly. Examples of this category of instruments are ammeters, voltmeters, watt-meters and energy meters.
Direct memory access – It is a computer technique which allows hardware sub-systems (like network or graphics cards) to access main system memory (random access m or RAM) independently of the central processing unit (CPU). By offloading data transfers, direct memory access (DMA) speeds up system performance and frees the central processing unit to execute other tasks.
Direct-metal deposition – It is an additive manufacturing technique where a focused energy source, typically a laser, melts metallic powder or wire as it is simultaneously injected onto a substrate. The molten metal rapidly solidifies to form a metallurgical bond, allowing for the creation, repair, or coating of complex 3D metal components.
Direct metal laser sintering – It is an additive manufacturing (3D printing) technique which uses a high-power laser to selectively fuse fine metal powders layer by layer. Guided by CAD (computer-aided design) files, the laser traces out 2D cross-sections in an inert chamber, melting or sintering the metal particles together to form a solid, complex part.
Direct methanol fuel cell – It is a sub-category of proton-exchange membrane fuel cells which converts liquid methanol directly into electricity without needing to reform it into hydrogen. It is highly valued for portable power applications because of the methanol’s high energy density and ease of storage. It is a system which turns liquid methanol and oxygen directly into electricity. It skips hydrogen storage by feeding a water-methanol mix straight to the anode, making power generation simple, portable, and safe at low operating temperatures.
Direct-methanol fuel cell membrane – It is a special plastic layer in a direct methanol fuel cell which lets tiny charged hydrogen particles pass through it. It blocks liquid fuel from leaking across, which keeps the power-making process working.
Direct method – It refers to an approach that solves a problem or calculates a physical value explicitly through straightforward observation, algebraic formulation, or numerical parameterization, rather than relying on iterative approximations or estimating functionally related variables. Direct methods also exploit relationships among the intensities to determine the crystal structure directly. They are today the most widely used tool for solving small- and medium-size crystal structures through powerful and sophisticated computer programmes. Direct method is also a solid-state process which extracts metals from ores at temperatures below the melting point of the metal. It uses reducing gases like hydrogen or carbon mono-oxide to strip oxygen from the ore, yielding a porous, solid product.
Direct microbial conversion – It is a single-step engineering process where micro-organisms simultaneously produce enzymes and carry out fermentation to transform complex organic bio-mass into useful fuels or chemicals like ethanol, completely combining hydrolysis and fermentation.
Direct model – In CAD (computer aided design) and 3D design, it is a history-free approach where a person edits geometry directly without parametric feature trees. In commerce, it normally refers to a direct-to-consumer (D2C) sales model. In mathematics, it is when people physically represent word problems using objects or drawings.
Direct modelling – It is a geometry-centered and history-free approach to 3D solid model construction which allows designers to quickly define and edit geometry through direct manipulation, facilitating design changes without the need for feature-level information. It is particularly beneficial for working with legacy and heterogeneous CAD (computer aided design) data.
Direct modulation – It is a method where an information signal controls a device’s output power by changing its input electrical drive current directly. It is very frequent in fibre optics and laser diodes to encode data by turning the light source on and off.
Direct normal irradiance – It is the quantity of solar radiation received directly from the sun per unit area on a surface which is kept perpendicular to the sun’s rays. It excludes scattered or diffuse light and is critical for tracking solar panels and concentrated solar power plants.
Direct normal irradiation – It is the quantity of solar radiation received per unit area on a surface which is always held perpendicular (normal) to the sun’s rays. It excludes diffuse and reflected light, making it important for concentrated solar power.
Direct numerical control computers – These computers distribute instructional data to, and collect data from, a number of machines or machining cells. These control computers occupy a location which is typically remote from the machines under their control. Direct numerical control computer software is developed not only to control individual pieces of production equipment but also to serve as part of a management information system in the manufacturing sector of an organization.
Direct numerical simulation – It is a method in computational fluid dynamics where the complete Navier-Stokes equations are solved numerically without using any turbulence models. It resolves all spatial and temporal scales of fluid motion, from large energy-containing eddies down to the smallest dissipative Kolmogorov scales.
Direct on-line starter – It is a kind of motor starter which does not reduce the voltage at the motor terminals.
Direct operating cost – It is an expense which ties directly to the production of a specific good, service, or operational activity. These costs rise or fall depending on the volume of output or activity, unlike fixed overhead.
Directory – It is a structural catalog which organizes files and other sub-directories on a computer or network. Also normally referred to as a ‘folder’, it acts as a virtual filing cabinet which manages the logical grouping of data to optimize searchability and access control.
Direct photolysis – It is a chemical process where a specific molecule absorbs light energy (photons) and breaks its own chemical bonds, splitting into smaller parts without needing any intermediate helper substances.
Direct powder rolling – It is a powder metallurgy technique which uses a rolling mill to directly compact metal powder into a green sheet (or strip). This process avoids the need for pre-formed billets or ingots, offering cost-effective and potentially less complex manufacturing of metallic sheets.
Direct pumping – It means sending water, fluids, or energy straight into a system using pumps without storing it in a high tank first. It appears in water supply networks, fire protection, and laser physics.
Direct-quadrature (DQ) control – It is a technique used to simplify the control of three-phase AC (alternating current) motors and power systems. It uses a mathematical formula (Park transformation) to change three-phase alternating current (AC) signals into simple DC (direct current) values which rotate with the motor. This makes it easy to control motor speed and torque.
Direct quenching – It means quenching carburized parts directly from the carburizing operation. It is also used for quenching pearlitic malleable parts directly from the malleabilizing operation.
Direct radiation – It is the radiation received directly from a source such as a nuclear power plant, rather than indirectly as a result of radioactive discharges.
Direct rapid cooling – It is universally known as quenching. It is the rapid extraction of heat from a heated or molten metal to achieve specific microstructural changes. By by-passing standard equilibrium cooling rates, it prevents the formation of soft micro-structures, frequently locking in a hard, strong phase called martensite.
Direct rapid tooling – It is the process of fabricating production-quality moulds, dies, or inserts directly from CAD (computer-aided design) data using ‘additive manufacturing’ or CNC (computer numerical control) machining. It by-passes intermediate steps like creating master patterns to rapidly produce metal-casting moulds, investment casting patterns, or metal tooling itself.
Direct redrawing – It is a secondary deep drawing process where a previously drawn cup is pushed into a smaller die to reduce its diameter and increase its height. The cup maintains its original orientation, meaning the exterior surface remains the exterior surface after redrawing.
Direct reduced iron – Direct reduced iron (DRI) is produced by the reduction of iron ore (in the form of lumps or pellets) by either non-coking coal or a reducing gas produced by reforming of natural gas. The reducing gas can also be produced by the gasification of coal. The reduction process is conducted at high temperature but substantially below the melting point of iron. Since the reduction reaction takes place in solid state, the lump or pellet retain their original shape, but are considerably lighter due to the removal of the oxygen from the ore. Hence the produced direct reduced iron has a highly porous structure. This porous structure gives direct reduced iron an appearance of a sponge and because of it, direct reduced iron is also known as sponge iron.
Direct reduced iron (DRI) production process – The direct reduced iron production process involves the intimate mixing of prepared (sized) iron ore with a reductant, which is also normally used for heating of the ore bed to the temperature needed to achieve adequate reduction rates. The reductant can be a gas or a solid. Majority of the direct reduced iron production processes are either natural gas based or coal based. Feed material for the direct reduction process is either sized iron ore of size ranging from 10 millimeters to 30 millimeters or iron ore pellets of size ranging from 8 millimeters to 20 millimeters produced in an iron ore pellet plant. The gas-based process uses a shaft furnace for the reduction reaction. The coal-based process uses any one of the four types of reactors for the reduction reaction. These reactors are (i) rotary kiln, (ii) shaft furnace, (iii) fluidized bed reactor, and (iv) rotary hearth furnace. Rotary kiln is the most popular reactor for the coal-based process.
Direct reduction – It consists of a set of processes for getting iron from iron ore, by reducing iron oxides without melting the metal. The resulting product is pre-reduced iron ore.
Direct reduction process – It is a method for producing solid iron from iron ores using a reducing agent, such as natural gas, resulting in direct reduced iron (DRI), which is mainly used as feedstock in electric arc furnace steelmaking.
Directrix – It is a fixed reference line used to define and construct conic sections (such as parabolas, ellipses, and hyperbolas). Along with a fixed point called the focus, the directrix establishes a curve by dictating how all of its points are spatially generated. The directrix is a plane curve used in the generation of a cone, where a point called the vertex does not lie in the plane of the directrix, and a straight line, known as the generatrix, passes through the vertex and touches the directrix.
Direct rolling – It is a continuous manufacturing process where a freshly cast, still-hot metal shape (like a slab or billet) is sent straight into a hot rolling mill without being allowed to cool completely or requiring secondary reheating.
Direct rolling and in-line heat treatment – These are highly efficient, continuous manufacturing techniques used in metallurgy to shape and refine metals (like steel) on the production line, saving energy by eliminating the need to reheat the material. Direct rolling is a continuous process where molten metal is cast into semi-finished shapes and rolled immediately while still retaining heat from the casting process. In-line heat treatment refers to applying thermal treatments (such as cooling, quenching, or tempering) directly to the metal while it is still traveling on the continuous rolling or production line. These two techniques are frequently combined in modern steel rolling mills (frequently referred to as thermo-mechanical controlled processing or TMCP) to create high-strength, low-alloy steels used in construction, bridges, and pipelines.
Direct sequence spread spectrum – It is a wireless communication modulation technique which multiplies data by a high-rate pseudo-random noise code, spreading the signal across a much wider frequency band to reduce interference, improve security, and increase transmission reliability.
Direct shear test – It is a simple laboratory method used in geo-technical engineering to find the shear strength, cohesion, and angle of internal friction of soil or rock samples.
Direct shipping ore – It is the high-grade iron ore after dry or wet sizing at the ore mine. This ore contains higher than 62 % of Fe (iron). This ore is normally known as natural ore or direct shipping ore. This ore can be directly used in the production of iron and steel.
Direct signal – It is an unhindered, line-of-sight wave or transmission which travels straight from a sender to a receiver without bouncing off surfaces or meeting obstacles. It provides the shortest path, fastest arrival time, and truest representation of the original data.
Direct solar gain – It is a passive solar heating method where sunlight enters a building directly through transparent openings like windows, striking interior surfaces and objects to convert light into thermal energy for space heating.
Direct solid solution treatment – It is a process applied to hot-rolled wire rods which utilizes the metal’s residual ‘sensible heat’. It by-passes the need for a separate, secondary solution heat treatment by applying controlled cooling directly after the hot-rolling process.
Direct stainless steelmaking – There have been efforts to use chromium and nickel ores for the production of stainless steel in place of the ferro-alloys. In Japan, a number of organizations have developed and are using such processes commercially. In particular, Kawasaki Steel (now JFE) has developed a process (KCS process) which smelts chromite ore (FeCr2O4 plus other oxides). Stainless steel is produced with converters, without any electric arc furnace operation, but using dephosphorized hot metal, chromite ore, and ferro-alloys as the major charge materials.
Direct steam generation – It is a thermal process where water is turned into steam directly inside the heat collector tubes, rather than using an intermediate heat transfer fluid like synthetic oil or molten salt. This steam then drives turbines for power or supplies industrial heat.
Direct stiffness method – It is a structural analysis technique which calculates internal forces, deflections, and support reactions by modelling a structure as simple elements joined at shared nodes. Using the matrix equation ‘P = KU’, it links external forces (P) and nodal displacements (U) through a global stiffness matrix (K).
Direct strain – It is the change in length per unit length of a structural member caused by an axial load, represented as ‘e = d/Lo’, where ‘d’ is the change in length and ‘Lo’ is the original length. It can be either a tensile (positive) strain or a compressive (negative) strain, applicable for relatively small distortions.
Direct strength method – It is a calculation technique used to design cold-formed steel structural members. Instead of checking individual plate elements one by one like older methods, direct strength method (DSM) looks at the whole cross-section as a single unit using its full, unreduced properties to find structural strength and predict failure.
Direct stress – It is the force per unit area acting on a material element in a state of tension, specifically across a surface perpendicular to the direction of the applied force. It is represented with double suffix notation to indicate the directional nature of the stress component.
Direct stress distribution – It is the way internal normal forces spread across a material’s cross-sectional area. It equals the applied axial force divided by the area (S = F/A). This pattern is uniform for centered loads, but it varies linearly or combines with bending when loads are off-centre.
Direct torque control – It is method of estimating motor torque as part of a variable speed motor drive.
Direct trans-esterification – It is a method in bio-diesel production where lipid extraction and trans-esterification occur simultaneously, allowing for the conversion of tri-glycerides from bio-mass into fatty acid methyl esters (FAME) without the prior separation of lipids.
Direct transmission – It is a communication method where the source node buffers a message and transfers it directly to the destination node, minimizing routing overhead by involving only the two nodes that need to communicate. This approach can face challenges because of the high encounter uncertainties, leading to potential delays and low delivery rates.
Direct tube extrusion – It is a manufacturing process where a solid metal billet is placed inside a container and pierced by a mandrel. A hydraulic ram forces the material forward through a die and around the mandrel, shaping it into a seamless tube. The ram and material move in the same direction.
Direct-write method – It is an additive manufacturing and micro-fabrication technique which deposits functional materials, patterns, or electronic circuits directly onto a substrate from digital computer-aided design (CAD) data. It eliminates the need for physical masks, custom tooling, or multi-step etching processes.
Direct-writing – It is a maskless manufacturing technique which deposits, alters, or patterns functional materials onto a substrate through computer control. It builds precise 2D or 3D microstructures directly from digital designs without physical masks or custom tooling.
Dirichlet boundary conditions – These conditions dictate the exact, fixed values a solution takes on the boundaries of a given physical or mathematical domain. For instance, in heat transfer, fixing a wall’s surface temperature is a Dirichlet condition. In computational simulations, this is also known as an ‘essential boundary condition’.
Dirichlet condition – It mainly refers to a boundary condition where the value of an unknown variable (like temperature or displacement) is fixed and explicitly specified along the boundary of a domain. It dictates exactly how a system interacts with its surroundings.
Dirichlet distribution – It is the multivariate extension of the Beta distribution, characterized by its simplicial nature and generated from a set of independent, gamma-distributed random variables which are normalized to the summation constant. It is noted for its inflexibility in fitting data.
Dirichlet function – It is a mathematical function which equals 1 for rational numbers and 0 for irrational numbers. It serves as a classic example of a pathological function since it is discontinuous everywhere and cannot be integrated using standard Riemann integration.
Dirichlet tessellation – It is very frequently known as a Voronoi diagram or Thiessen polygons. It is a way to split a flat space into regions. Each region surrounds a specific point, containing all the locations in that space which are closer to that point than to any other point.
Dirichlet’s theorem on arithmetic progressions – It states that for any two positive integers ‘a’ and ‘d’ which share no common factors other than 1 (coprime), the arithmetic progression (a, a+d, a+2d, a+3d, ——–) contains an infinite number of prime numbers.
Dirt – It is the foreign debris from rolling or post-rolling operations imbedded in or under the coating. It is also the extraneous material entering a mould cavity and normally forming a blemish on the casting surface.
Dirt content – It is a measure of the size and concentration of foreign particles present in a lubricant. Dirt content is normally reported as the number of particles per cubic centimeter, for specified particle Sizes.
Dirt trap – It is a specialized device, strainer, or pipe fitting designed to capture and remove solid contaminants, debris, and particulate matter from a flowing medium. It protects downstream equipment (like valves, pumps, and regulators) from clogging, abrasive wear, and system failure. It is also a well which is used in a gating system to entrap the first metal poured, which can contain dirt or unwanted particles.
Dirty casting – It refers to a casting which contains an excessive quantity of unwanted, non-metallic particles (frequently called inclusions) suspended inside the solidified metal body or across its surface. These ‘dirt’ particles permanently weaken the component and ruin its surface finish.
Dirty paper coding – It is a smart way to send data through a communication channel when the sender already knows about the upcoming signal interference. By preparing or precoding the data beforehand, the sender cancels out this known interference completely without needing extra transmission power.
Dirty steel – It refers to steel which contains high levels of unwanted chemical impurities (like sulphur, phosphorus, nitrogen, and hydrogen) and non-metallic inclusions. These embedded defects, such as oxides, sulphides, and silicates, act as micro-flaws which degrade the steel’s mechanical properties.
Disamatic moulding – It is a type of sand moulding process in which molten metal is poured into a mould made of sand to make gray iron castings. Disamatic machines are designed to provide moulds built for vertical casting and the moulds are created in a vertical orientation. Disamatic machines create flaskless moulds. A Disamatic moulding machine is a vertically parted sand moulding machine. The vertical moulding machine is frequently the choice for production of very close tolerance gray iron castings.
Disappearing filament pyrometer – It is also called optical pyrometer. It is a non-contact temperature instrument which measures the heat of glowing, incandescent objects by visually comparing their brightness to a heated reference filament inside the device. It is widely used in foundries, glassworks, and metal forging.
Disappearing stop – It is also called disappearing stopper. It is a mechanical barrier used on the exit roller tables of steel and metal rolling (metalworking) to halt, align, or accumulate rolled metal products (like reinforcement bars, rods, or strips) before the bundling, shearing, or cooling processes. It operates by temporarily rising above the conveyor line to catch the moving metal, then retracting (disappearing) beneath the surface to let the bundled or cut material smoothly move forward without obstruction.
Disaster – It is defined as an event or series of events, which gives rise to causalities and damage or loss of properties, infrastructures, environment, essential services or means of livelihood on such a scale which is beyond the normal capacity of the affected community to cope with. Disaster is also described as a ‘catastrophic situation in which the normal pattern of life or eco system has been disrupted and extra ordinary emergency interventions are required to save and preserve lives and / or environment’.
Disaster management – It consists of organization, planning and application of measures preparing for, responding to and recovering from disasters. It is the process of effectively preparing for and responding to disasters. It involves strategically organizing resources to lessen the harm that disasters cause. It also involves a systematic approach to managing the responsibilities of disaster prevention, preparedness, response, and recovery.
Disaster management system – It is a structured set of policies, tools, and coordinated processes designed to protect communities by preventing, preparing for, responding to, and recovering from natural or man-made disasters. Its main goal is to minimize loss of life, property, and environmental damage.
Disaster mitigation – It is the ongoing process of taking action before a disaster strikes to reduce or eliminate long-term risks to human life, property, and the environment. It involves lowering vulnerability to natural or man-made hazards.
Disaster planning – It is the structured process of creating policies, procedures, and systems to prepare for, respond to, and recover from natural or human-made emergencies. Its main goal is to protect human life, reduce property damage, and ensure continuity of operations.
Disaster preparedness – It means taking advance actions to get ready for natural or human-made emergencies. The main goal is to save lives, cut down injuries, and protect property. It turns sudden panic into a clear and safe plan of action.
Disaster prevention – It refers to the outright avoidance of the adverse impacts of hazardous events and the complete elimination of corresponding risks. It focuses on pre-event actions that lower community vulnerability and exposure.
Disaster recovery – It is the systematic process of restoring vital infrastructure, IT (information technology) systems, and critical operations after a catastrophic event. It encompasses the specific policies, tools, and technical procedures utilized to minimize data loss and safely resume operations.
Disaster recovery plan – It is a documented, structured set of guidelines which outlines how an organization responds to unplanned incidents, such as natural disasters, cyberattacks, or infrastructure failures. Its main goal is to restore important systems, technology assets, and data to minimize downtime and avoid operational loss.
Disaster relief operations – These are coordinated efforts to provide important services such as food, water, shelter, protection, and medical help to victims during emergency situations caused by man-made or natural disasters. These operations typically involve establishing communication infrastructures, conducting search and rescue missions, and delivering necessary first aid services.
Disaster response – It is the set of urgent actions taken right before, during, or right after an emergency. Its main goal is to save lives, keep people safe, and provide basic needs like food, water, and shelter.
Disaster risk – It is the likelihood over a specified time period of severe alterations in the normal functioning of an organization or a society because of the hazardous physical events interacting with vulnerable conditions, leading to widespread adverse human, material, economic, or environmental effects which need immediate emergency response to satisfy critical human needs and which can need external support for recovery.
Disaster risk management – It consists of processes for designing, implementing, and evaluating strategies, policies, and measures to improve the understanding of disaster risk, foster disaster risk reduction and transfer, and promote continuous improvement in disaster preparedness, response, and recovery practices, with the explicit purpose of increasing human security, well-being, quality of life, and sustainable development.
Disaster risk reduction – It denotes both a policy goal or objective, and the strategic and instrumental measures employed for anticipating future disaster risk. It is reducing existing exposure, hazard, or vulnerability; and improving resilience.
Disbond – It is an area within a bonded interface between two adherends in which an adhesion failure or separation has occurred. It is also an area of separation between two laminae in the finished laminate (in this case, the term delamination is normally preferred).
Disbond growth – It is the progressive spreading or expansion of a separation between two bonded materials (such as an adhesive layer, a composite face sheet, and a core structure). Under mechanical stress or fatigue, a small initial defect or unbonded area grows larger, which can weaken joint strength and lead to structural failure.
Disbondment – It is the destruction of adhesion between a coating and the surface coated.
Disc – It is also spelled as disk. The disc is that part of the valve which allows, throttles, or stops the fluid flow, depending on its position. For a valve having a bonnet, the disc is the third primary principal pressure boundary. The disc provides the capability for permitting and prohibiting fluid flow. With the disc closed, full system pressure is applied across the disc if the outlet side is depressurized. For this reason, the disc is a pressure-retaining part. In the case of a plug or a ball valve, the disc is called plug or a ball. The disc is the third most important primary pressure boundary. With the valve closed, full system pressure is applied across the disc, and for this reason, the disc is a pressure related component. Discs are normally forged, and in some designs, hard surfaced to provide good wear properties. Disc is also a non-volatile physical memory device which stores digital data using magnetic or optical technology. It consists of one or more rigid, rapidly rotating circular plates (platters) coated with materials which can be permanently altered to represent binary 1s and 0s.
Discard – It is also called butt. It is the unusable, left-over portion of a metal billet which remains in the extrusion container after the bulk of the material has been pushed through the die.
Disc bend test – It is a specialized mechanical test used to evaluate the ductility, fracture toughness, and deformation mechanisms of a material using miniature, disc-shaped samples. The test is specifically designed for situations where only limited material is available, such as assessing irradiated alloys for nuclear reactors or precious laboratory samples.
Disc brake – It is a system which slows or stops a wheel by using a caliper to squeeze brake pads against a flat metal disc (rotor) which turns with the wheel. This friction changes the motion into heat to slow the vehicle.
Disc compression test – It is frequently referred to as a Brazil test, diametral compression test, or ring compression test. It is a metallurgical and mechanical evaluation method. In this test, a cylindrical, flat ‘slug’ or disc of metal is placed on its side and compressed between two flat platens or dies.
Disc deflection method – It typically refers to small punch testing (SPT) or disc bend testing. It is a miniaturized mechanical testing technique where a small, thin disc-shaped metal sample (frequently around 8 millimeters to 10 millimeters) is placed over a circular die and indented by a spherical punch while force and continuous disc deflection are measured. Disc deflection method also refers to the use of specialized formulas based on plate and shell theory to calculate how much a flat, circular plate (disc) displaces when subjected to an external load. It is a method of analyzing out-of-plane bending or deflection of a circular disc or plate, where the displacement is measured perpendicular to the disc’s original flat plane.
Disc deflection test – It is frequently categorized as a miniaturized disc bend test (MDBT) or small punch (SP) test. It is a metallurgical evaluation method. It uses small, thin, disc-shaped samples to determine mechanical properties like yield strength, tensile strength, and fracture toughness.
Disc electrode – It is a small, flat, circular piece of conductive material, such as platinum, gold, or glassy carbon, embedded flush into the end of an inert, non-conductive rod. It serves as a working electrode in electrochemical experiments to measure current and study chemical reactions.
Disc file – It is a collection of data or instructions stored as a single named unit on a computer’s storage media, such as a hard drive, solid-state drive, or optical disc. It can refer to any standard saved document, programme, or database, or specifically to a disk image file which replicates an entire drive.
Disc filter – It is a type of mechanical filtration device used to separate suspended solids from liquids, very frequently in water treatment, and industrial processes. It consists of a stack of hollow, grooved plastic or metal rings compressed together on a central spine or shaft, creating a three-dimensional depth-filtration matrix.
Disc grinding – It consists of grinding with the flat side of an abrasive disk or segmented wheel. It is also called vertical-spindle surface grinding.
Discharge – It is the release of gaseous or liquid materials to the environment.
Discharge area – It is the cross-sectional space where a fluid, water, or air emerges, flows out, or escapes from a system like a pipe, valve, or groundwater basin. In fluid dynamics and hydrology, it represents the specific area (A) used to compute volumetric flow rate (Q = A × V).
Discharge blow tank – It is a high-pressure pressure vessel used in pneumatic conveying systems to feed and transport bulk dry solids, powders, or granular materials in batch cycles. Compressed air fluidizes the contents inside the tank and forces them out through a discharge pipe.
Discharge capacity – it is the total quantity of electrical energy a battery can deliver under specific test conditions from a fully charged state down to a defined cut-off voltage. It measures how much usable charge a battery holds.
Discharge chamber – It is a sealed or enclosed space where a gas breaks down electrically to form plasma, or where compressed fluids and exhaust gases collect and exit a mechanical system. It is used industrial machinery.
Discharge chute – It is a designed channel for materials to exit the conveyor, needing periodic inspections to ensure proper flow and prevent material build-up.
Discharge coefficient – It is the ratio of actual fluid flow through a device like a nozzle, orifice, or pipe to the ideal or theoretical flow. It is a dimensionless number which quantifies the flow efficiency of a fluid through an orifice, with a typical value of 0.61 assumed for sharp-edged orifices at high Reynolds numbers.
Discharge condition – It normally refers to the specific operational, environmental, or physical state under which a fluid flows out of a system (fluid mechanics) or electrical energy is released from a component (electrical engineering).
Discharge connection – It is the outlet port, flange, or fitting on a fluid-handling machine, such as a pump, compressor, or blower, where the pressurized fluid, gas, or mixture exits the device and enters the external piping system.
Discharge crater – It is a microscopic, pit-shaped depression formed on the surface of an electrode or metal workpiece. It is caused by intense local heating, melting, and vapourization from a single electrical spark or plasma discharge, normally occurring during electrical discharge machining (EDM) or from electrical contact arcs.
Discharge damper – It is a mechanical control valve or plate placed at the outlet (discharge side) of a pump, fan, or blower. It regulates system pressure, adjusts volumetric flow rate, or isolates equipment by changing the size of the flow opening.
Discharged energy – It is the process of releasing stored electrical power from a source like a battery, capacitor, or energy storage system. It converts stored chemical or physical energy into an active electric current to perform work or power a connected external load.
Discharge electrode – It is a high-voltage conductive component used to ionize gas, create a corona discharge, and charge airborne particles. It is very frequently found in industrial electrostatic precipitators (ESPs) to remove dust and smoke from exhaust gases.
Discharge end – It is the location on a conveyor where goods are removed for further processing, necessitating efficient material flow and regular inspections.
Discharge energy – It is the total quantity of electrical or stored energy released during a single pulse, breakdown, or operational discharge event. It measures the capacity converted into heat, light, or mechanical work when a system like a capacitor, battery, or spark gap discharges.
Discharge enthalpy – It is the total specific energy per unit mass (h = u + Pv, where ‘u’ is internal energy, ‘P’ is pressure, and ‘v’ is specific volume) of a working fluid as it exits a thermodynamic system, component, or device like a compressor, turbine, pump, or geothermal well. It dictates the exiting fluid’s thermal and flow energy content.
Discharge lamp – It is an artificial light source which produces light by passing an electric current through a gas or metal vapour, causing the atoms to ionize and emit radiant energy.
Discharge line – It is a pipe or conduit which transports high-pressure fluids, gases, or-superheated vapours away from a pressure-generating source, such as a compressor, pump, or processing unit, toward a condenser, receiver vessel, or environmental disposal point.
Discharge mode – It defines how a system releases stored electrical energy, plasma, or fluids. The term mainly applies to electrical power systems or plasma physics, describing specific operational states like constant current, glow, or arc discharge during energy transfer.
Discharge of a capacitor – It is the process where a charged capacitor releases its stored electrical energy through an external circuit or load, neutralizing the charge imbalance between its plates until the terminal voltage drops to zero.
Discharge period – It defines the specific time duration over which a fluid, stored energy, or electrical charge is actively released from a system.
Discharge pipe – It is an outbound conduit which transports fluids, gases, or waste away from a mechanical system, pump, compressor, or plumbing fixture to a designated disposal, treatment, or environmental release point.
Discharge point – It is the specific location or physical outlet where fluids, stormwater runoff, treated wastewater, or exhaust gases exit a system, pipe, or site boundary into the environment or a receiving utility network.
Discharge port – It is the exit opening on a positive displacement machine, pump, or compressor where compressed gas, air, or working fluid is expelled from the working chamber. Its size and geometry directly dictate flow velocity, pressure drop, and overall volumetric efficiency.
Discharge pressure – It is the total pressure on the outlet side of a pump measured near the outlet port. It is sometimes called the back pressure or backing pressure. It is also known as outlet pressure, exhaust pressure, or fore-pressure.
Discharge reaction – It is the spontaneous electro-chemical process inside a battery or fuel cell where stored chemical energy converts into electrical energy. Oxidation occurs at the negative electrode (anode) to release electrons, and reduction occurs at the positive electrode (cathode) to absorb them, driving current through an external circuit.
Discharge side – It refers to the outlet or high-pressure section of a fluid-handling system where media, such as liquids, gases, or air, are expelled or transported away from a device like a pump, compressor, or fan.
Discharge temperature – It is the temperature of a gas, air, or fluid as it exits the outlet or discharge valve of a device like a compressor, pump, or fan. It rises since compressing of a fluid increase both its pressure and thermal energy.
Discharge valve – It is a mechanical device fitted at the outlet or exit port of fluid-handling equipment—such as pumps, compressors, or pressure vessels, to control, direct, or stop the flow of discharged liquids, gases, or bulk materials.
Discharging period – It is the specific time duration needed for a system, component, or storage medium to release its stored energy, fluid, or mass down to a specified minimum threshold or complete depletion.
Disc image – It is a single file containing an exact, sector-by-sector copy of a data storage medium, such as a hard drive, solid-state drive. It preserves all data, file systems, hidden metadata, and boot structures.
Disc image file – It is a single computer file which contains an exact, sector-by-sector copy of the data and structure from an optical disc. It acts as an exact digital twin of the physical media.
Discipline – It is defined as a force which prompts the employees to observe rules, regulations, and procedures which are considered necessary for the effective functioning of the process. It is an activity which involves acting in accordance with a set of known rules, proven guidelines, and conventions framed for the purpose. It is basically an attitude and the behaviour of the employees who are operating the process and is strongly influenced by the organizational culture and the environment in which the process is functioning.
Disciplined oscillator – It is a frequency generation system whose output is continuously monitored and electronically steered (or disciplined) to align with a highly accurate external reference, such as an atomic clock.
Disciplined worker – Disciplined worker strictly adheres to structured processes, technical specifications, and safety codes. They prioritize systematic work-flows to eliminate guesswork and ensure consistent, high-quality output.
Disciplined working – It takes place in the organization occur when the employees follow organizational rules, which are official instructions in respect of what employees have to and are allowed to do and what they are not allowed to do.
Disciplined working approach – It refers to the systematic application of standardized methodologies, scientific principles, and quantifiable processes to develop and maintain systems. It ensures projects are safe, reliable, and consistent by eliminating human error and managing variables.
Disclosure – It encompasses an organization’s ethical and legal obligation to reveal potential conflicts of interest, safety risks, or hidden information to the customers or public.
Disc machine – In tribology, it a testing machine for rolling or rolling / sliding contact in which two disc-shaped rollers, with parallel axes of rotation, make tangential contact on their circumferences as they move relative to one another. One or both discs can be crowned on the rolling-contact surface.
Disc method – It refers to a mathematical integration technique used to find the volume of a 3D solid by slicing it into infinitely thin disks. Disc method is a standard sample preparation technique used to create electron-transparent thin foils (typically 100 nano-meters or less thick) from bulk metals. It involves mechanically cutting a small, standard-sized disc (normally 3 millimeters in diameter) from a bulk sample and using chemical, electro-chemical (electro-polishing), or physical thinning processes. The resulting thin foil is utilized for microstructural analysis under a transmission electron microscope (TEM).
Disconnections – These refer to the physical or logical breaking of a link between systems, circuits, or chemical bonds. This includes electrical isolation for safety, network termination, or the mental breakdown of molecular bonds in chemical design.
Discontinuities and defects – Discontinuities are interruptions in the normal physical, metallurgical, or mechanical structure of a material, while a defect is a discontinuity (or a group of them) which exceeds allowable limits set by industry codes, rendering the part unfit for its intended service and subject to rejection or repair. The relationship between the two is defined by the rule which is ‘all defects are discontinuities, but not all discontinuities are defects. Understanding how to classify an imperfection helps in evaluating the structural integrity of manufactured components.
Discontinuities as dislocation sources – Discontinuities like grain boundaries, precipitates, and micro-cracks act as dislocation sources by serving as stress concentrators and sites for heterogeneous nucleation. When a material experiences stress, these local geometric or structural irregularities trigger the continuous generation of new dislocations, facilitating plastic deformation.
Discontinuity – It is an interruption in the normal physical structure or configuration of a part, such as cracks, laps, seams, inclusions, or porosity. A discontinuity may or may not affect the utility of the part. It is also an interruption of the typical structure of a weldment, such as a lack of homogeneity in the mechanical, metallurgical, or physical characteristics of the material or weldment. A discontinuity is not necessarily a defect.
Discontinuity crack – It is a fracture-type interruption in a material’s physical structure, characterized by a sharp tip and high length-to-width ratio. A discontinuity is just an irregularity, but when stresses exceed the material’s strength, it becomes a crack. Understanding discontinuity cracks involves looking at how they form, their specific types, and their danger level.
Discontinuity surface – It is a break, plane, or imperfection which interrupts the uniform physical, mechanical, or metallurgical properties of a material, rock mass, or structure. It is not automatically a defect. It only becomes a defect if it exceeds safe design limits.
Discontinuous conduction mode – It is a state in power electronics where the current flowing through an inductor or transformer completely drops to zero during a portion of the switching cycle. It typically occurs in direct current-direct current (DC-DC) converters under light-load conditions when the total energy stored in the inductor is depleted before the cycle concludes. In contrast to continuous conduction mode (CCM), where current flows uninterrupted through the inductor at all times, discontinuous conduction mode (DCM) operation alters the converter’s properties, making the output voltage dependent on the load and increasing output impedance.
Discontinuous control – It is a type of control action where the output signal from a controller does not change smoothly. Instead, it switches abruptly between two or more fixed states (such as fully ‘on’ and fully ‘off’, or high and low) based on the system’s input or error value.
Discontinuous deformation analysis – It is an implicit numerical method in rock mechanics and geological engineering used to compute the large movements, rotations, and deformations of independent blocks interacting along joints, fractures, or distinct boundaries.
Discontinuous dynamic recrystallization – It is a process where new, strain-free grains nucleate and grow within a metal while it is being plastically deformed at high temperatures. Driven by stored deformation energy, it acts as a softening mechanism, relieving stress and significantly refining the material’s grain size.
Discontinuous extrusion – It is also known as batch or ram extrusion. It is a manufacturing process where a discrete batch of pre-heated raw material is loaded into a chamber and forced through a die using a reciprocating piston or ram. Unlike continuous screw-based methods, this process pauses between batches to reload.
Discontinuous fibre-reinforced composite – It is a ceramic-matrix composite material reinforced by chopped fibres.
Discontinuous Galerkin – It refers to a numerical technique which utilizes discontinuous basis functions to represent unknown fields, enabling high-order accuracy and the ability to handle complex meshes while enforcing continuity and boundary conditions in a weak sense through boundary integrals. This method is particularly effective in multi-physics simulations and allows for efficient parallelization.
Discontinuous Galerkin (DG) method – It is an advanced finite element technique used in engineering and applied physics to solve complex differential equations. It breaks a shape into small cells and uses mathematical functions inside each cell which can break or jump at the edges. Neighboring cells talk to each other using special numerical flux formulas.
Discontinuous grain growth – It is a phenomenon where a select few energetically favourable crystallites (grains) grow exceptionally fast, consuming surrounding smaller grains. This results in a heterogeneous, bimodal microstructure of mixed large and small grains.
discontinuous joint – It is a natural break or fracture in a rock mass which has finite length and is interrupted by intact rock bridges. Unlike continuous joints which cut entirely through a rock section, discontinuous joints need shearing or breaking through remaining rock bridges to fail.
Discontinuous metal-matrix composite – It is an engineered material consisting of a continuous metallic base (like aluminum, titanium, or copper) reinforced with discrete, non-continuous ceramic or metallic additions. These reinforcements are typically particulates (powders), whiskers, or short / chopped fibres (e.g., SiC or Al2O3). Unlike continuous fibre metal-matrix composites (MMCs), which rely on long, aligned filaments for highly directional, anisotropic strength, discontinuous metal-matrix composites (DMMCs) provide roughly isotropic (uniform in all directions) mechanical properties.
Discontinuous mode – It is a state in which an inductor completely drains its stored energy before the completion of the switching cycle, resulting in all current accumulated during the charging interval being discharged within the same cycle.
Discontinuous mode operation – It describes a state where the current through an inductor or transformer completely drops to zero during a part of the switching cycle. This means the magnetic core or inductor fully empties its stored energy before the next cycle starts. It is frequently used since it offers the advantages of easy control and low diode reverse recovery loss.
Discontinuous operation – It occurs when the current through an inductor or transformer drops completely to zero for a portion of the switching cycle. This means the stored energy fully empties before the next cycle begins.
Discontinuous point – t is a specific location where a system’s mathematical function breaks, jumps, or goes to infinity instead of forming a smooth, connected line. It happens when a rule fails since a value is missing, left and right sides do not match, or numbers grow without end.
Discontinuous precipitation – It is the precipitation from a supersaturated solid solution in which the precipitate particles grow by short-range diffusion, accompanied by recrystallization of the matrix in the region of precipitation. Discontinuous precipitates grow into the matrix from nuclei near grain boundaries, forming cells of alternate lamellae of precipitate and depleted (and recrystallized) matrix. It is frequently being referred to as cellular or nodular precipitation.
Discontinuous reception – It is an energy-saving protocol used in wireless communication like LTE (long term evolution) and 5G. It lets a mobile device turn off its radio receiver during quiet times. The device only wakes up at scheduled times to check for data. This saves battery life.
Discontinuous system – It is a dynamical system which experiences abrupt, non-smooth changes in its states, signals, or governing equations. Unlike smooth continuous systems, its behaviour involves sudden jumps, impacts, or discrete switching actions rather than smooth transitions over time. While continuous systems use smoothly varying time signals, discontinuous systems rely on step changes, relay actions, or hybrid mode updates.
Discontinuous transmission – It is a method used in communication systems to turn off the radio transmitter during silent pauses in a conversation. It relies on a voice activity detector to spot when a person stops speaking. This process saves battery power and reduces network noise.
Discontinuous yielding – It is a material behaviour where a stress-strain curve shows a sudden drop from an upper yield point to a lower yield point, followed by a flat or wavy plateau of plastic deformation. It marks a sharp, non-smooth transition from elastic to plastic behaviour. It is the non-uniform plastic flow of a metal showing a yield point in which the plastic deformation is inhomogeneously distributed along the gauge length. Under some circumstances, it can occur in metals not showing a distinct yield point, either at the onset of or during plastic flow. It is a phenomenon where a material experiences a non-smooth, abrupt transition from elastic to plastic deformation. It is characterized on a stress-strain curve by a sharp peak (the upper yield point), a sudden drop in stress, and a horizontal plateau where the material continues to stretch without any increase in stress (the lower yield point and Luders strain). This behaviour, very frequently observed in low-carbon (mild) steels and certain other alloys, is dictated by specific atomic-level mechanisms.
Discontinuously reinforced aluminum – It is a type of metal matrix composite (MMC). It consists of a conventional aluminum alloy matrix (e.g., 2000, 6000, or 7000 series) mechanically combined with discrete ceramic or non-metallic reinforcements, such as silicon carbide (SiC), boron carbide (B4C), or alumina. Discontinuously reinforced aluminum (DRA) materials get their defining characteristics from their metallurgy and physical composition.
Discontinuously reinforced aluminum metal matrix composites – These are engineered materials comprising an aluminum alloy base (matrix) embedded with unaligned ceramic or metallic reinforcements (like particles, whiskers, or short fibers). Unlike continuous-fibre composites, they can be processed and shaped using standard industrial techniques like forging and extrusion.
Discontinuously reinforced aluminum alloy metal-matrix composites – These composites represent an advanced aluminum materials concept whereby ceramic particles, or whiskers, are added to aluminum-base alloys through the use of either ingot-melting or casting and / or powder-metallurgy (P/M) techniques.
Discounted cash flow – Discounted cash flow analysis is a method of valuing a project, organization, or asset using the concepts of the time value of money. All future cash flows are estimated and discounted by using cost of capital to give their present values. The sum of all future cash flows, both incoming and outgoing, is the net present value (NPV), which is taken as the value or price of the cash flows in question. Using discounted cash flow analysis to compute the net present value takes as input cash flows and a discount rate and gives as output a present value. The opposite process takes cash flows and a price (present value) as inputs, and provides as output the discount rate. The most widely used method of discounting is exponential discounting, which values future cash flows as ‘how much money would have to be invested currently, at a given rate of return, to yield the cash flow in future’.
Discounting – It is the act of estimating the present value of a future payment or a series of cash flows that are to be received in the future. Discounting is a key element in valuing future cash flows.
Discovery – It is the act of locating a resource which is previously unknown and which meets certain functional criteria. It involves matching a set of functional and other criteria with a set of resource descriptions. The goal is to find an appropriate resource.
Discovery well – It is the first successful exploratory or wildcat well drilled into a new geological structure or unproven area that finds and recovers commercial quantities of petroleum, natural gas, or other subsurface resources to the surface, proving the existence of a new reservoir.
Disc pelletizer – It is also known as a pan granulator. It is a rotating, inclined circular pan which turns fine powders and moisture-laden materials into uniform, spherical pellets. It relies on a non-pressure ‘tumble growth’ agglomeration process, combining gravity, centrifugal force, and liquid binders to coalesce fine particles into larger, structured balls.
Disc player – It is an electronic machine which uses a laser beam to read digital data stored on optical discs. It converts the scanned optical patterns into audio or video signals for playback through speakers or a television.
Disc pressure test – It is a specialized mechanical evaluation mainly used to determine a metal’s susceptibility to hydrogen environment embrittlement (HEE).
Discrepancy measure – It is a quantitative metric used to calculate the difference, error, or distance between a measured value and a true reference value, or between a computational model’s predictions and real-world physical data. A discrepancy occurs when two values or datasets do not overlap within their stated uncertainty bounds, revealing system faults or model inaccuracies.
Discrepancy principle – It is frequently called Morozov’s discrepancy principle. It is a rule used to choose the optimal regularization parameter when solving noisy, ill-posed inverse problems. It stops fitting the data precisely when the residual error matches the known noise level.
Discrete alphabet – It is a finite, non-empty set of distinct, identifiable symbols or values used to represent data, transmit messages, or encode states. Examples include binary digits {0, 1}, alphanumeric characters, or specific voltage levels.
Discrete analogue – It is a step-by-step or countable mathematical model which mirrors a continuous system. It replaces smooth differential operators, continuous curves, or real-number functions with difference equations, sequences, or matrices so computers can process physical laws.
Discrete approach – It is a modelling and analysis method which treats a system, material, or time domain as separate, individual units or distinct particles rather than a smooth, continuous medium. It tracks individual interactions, separate blocks, or distinct state changes over specific points.
Discrete atom method – It examines the general coherency problem, based on chemical statistical mechanics and linear elasticity. The discrete atom method (DAM) appears to be an answer for the study of predicting microstructural evolution in several stressed alloy systems.
Discrete case – It describes a system, model, or variable which uses distinct, separate, and countable values or time steps rather than a smooth, unbroken continuous range. It splits data, states, or time into individual chunks like integers, binary on / off signals, or clock ticks.
Discrete component – It is a standalone electronic part which has only one circuit element and performs a single, specific function. Unlike integrated circuits (ICs) which pack millions of parts onto a single silicon chip, discrete pieces are packaged individually with two or more connecting leads.
Discrete control – It means managing a system using distinct, separate steps, signals, or values rather than a smooth, continuous flow. It splits into two main types namely discrete-state (logical / sequential) control and discrete-time (sampled-data) control.
Discrete cosine transform – It is a mathematical technique for representing a sampled signal as a sum of cosine waves of different frequencies. It converts data from the spatial domain (e.g., pixels in an image or audio amplitudes) into the frequency domain. It expresses these data points as a sum of real-valued cosine functions oscillating at different frequencies. Since most natural signals have neighbouring points which are highly correlated, the discrete cosine transform (DCT) concentrates the bulk of the signal’s information (its ‘energy’) into just a few low-frequency coefficients. The remaining high-frequency coefficients, which contain less visually or aurally important details, can then be discarded without a noticeable loss in quality.
Discrete data – It is numerical or categorical information which consists of distinct, separate, and countable values. It can only take specific values (normally whole numbers) with clear gaps in between, meaning a person counts items rather than measure them on a continuous scale.
Discrete dislocation dynamics – It is a meso-scale computer simulation method used to model crystal plasticity by tracking the collective movement, multiplication, and interaction of individual dislocation line defects. It bridges the gap between atomic-scale molecular dynamics and large-scale continuum plasticity models.
Discrete effort – It is the work directly associated with components of a work breakdown structure. It is directly measurable. Discrete effort is one of three types of activities used to measure work performance as part of earned value management.
Discrete element method – It is a numerical scheme used for simulating the behaviour of interacting discrete bodies, capable of handling finite displacements and recognizing different contacts or inter-actions among them. It facilitates the definition of particle interactions and motion, allowing easy coupling with other particle-based methods.
Discrete element modelling – It is a numerical method used to simulate the mechanical behaviour of a large number of interacting particles or distinct bodies. It works by applying Newton’s laws of motion to track the individual translation, rotation, and collisions of each element over time.
Discrete event dynamic system – It is a man-made or natural system whose state changes at discrete points in time in response to sudden, asynchronous occurrences called events. Unlike continuous systems governed by differential equations, its state stays fixed until an event triggers a transition.
Discrete event simulation – It is a modelling method where a system’s state changes only at specific, distinct points in time when an event occurs. Between these events, the system is assumed to be completely static, and the simulation clock jumps directly from one event time to the next.
Discrete finite element model – It is a mathematical representation of a continuous physical system broken down into a finite number of connected geometric sub-regions called elements. This process converts complex differential equations into solvable algebraic matrix equations to predict stress, strain, and structural behaviour.
Discrete form – It is the algebraic representation of a continuous governing equation. It replaces smooth, continuous mathematical functions with values at distinct, countable points. This conversion allows computers to solve complex differential equations using numerical analysis.
Discrete Fourier series – It is the Fourier transform for periodic sequences, serving a similar role for these sequences as the Fourier transform does for non-periodic sequences. It provides a theoretical basis for the discrete Fourier transform (DFT), which is important in signal and image processing.
Discrete Fourier transform – It is a mathematical technique for representing a sampled signal as a sum of sine and cosine waves of different frequencies.
Discrete Fourier transform (DFT) test – It is a statistical tool used to identify periodic or repetitive patterns within a sequence of numbers. The test analyzes a bit stream by checking if the number of repetitive patterns (peaks in the frequency domain) considerably exceeds or deviates from what is expected in a truly random sequence.
Discrete fracture network – It is a computational model used in geology, reservoir engineering, and mining to explicitly represent the geometries and spatial arrangements of individual fractures within a rock mass. Instead of assuming a uniform medium, discrete fracture networks (DFNs) capture individual fracture properties like orientation, size, aperture (width), and connectivity. Discrete fracture networks generate fractures using either deterministic data (like mapped faults and core logging) or stochastic algorithms (probabilistic distributions based on observed trends).
Discrete fracture network models – These models map out individual fractures, capturing their specific size, orientation, shape, aperture, and spatial connectivity. Discrete fracture network (DFN) models are built using a combination of deterministic data and stochastic (probabilistic) generation techniques. The resulting network serves as the structural foundation for advanced numerical simulations.
Discrete frequency domain – It represents a finite set of specific frequency components which make up a sampled or periodic signal. Instead of tracking changes over continuous time, it maps a signal’s magnitude and phase to distinct, indexed frequency bins using tools like the discrete Fourier transform (DFT).
Discrete geometric element – It is a distinct, separable building block used in discrete geometry to construct or model shapes, spaces, and data. Instead of using smooth, continuous lines, a discrete element is a foundational unit such as a point, vertex, edge, triangle (mesh), voxel, or polygon. Since these elements are distinct and countable, they form the basis of computer graphics, engineering simulations, and digital data analysis.
Discrete geometry – It is s a branch of mathematics which studies geometric objects and properties which are countable, distinct, or finite, rather than continuous. It focuses on the combinatorial and structural arrangements of objects like points, lines, polygons, and polyhedra, mainly relying on exact lengths and angles rather than calculus or infinitesimals.
Discrete gust – It is a single, isolated atmospheric disturbance or sudden change in wind velocity defined by a specific geometric shape, magnitude, and duration. It is used to test the structural strength and dynamic response of aerospace, wind energy, and civil engineering structures.
Discrete input – It is a signal which has only two distinct, opposite states namely on or off, true or false, or 1 or 0. It tells a system whether a specific condition or physical event is present or absent.
Discrete layer – It refers to a layer-wise modelling approach used for analyzing laminated composite structures, shells, or smart materials. In this method, kinematic assumptions or displacement fields are defined independently for each distinct material layer or ply through the thickness, rather than treating the entire laminate as a single homogenized block.
Discrete memory-less channel – It is a statistical communication model where the input and output alphabets are finite sets of discrete symbols, and each output symbol depends solely on the corresponding current input symbol rather than any past inputs.
Discrete method – It is a mathematical or computational technique which breaks down a problem or system into separate, distinct, and countable units (like individual numbers, points, or particles) rather than smooth, unbroken ranges.
Discrete model – It is a mathematical or computational representation where system states and changes occur at distinct, separate, and countable time intervals or values, rather than through smooth, unbroken continuous variation.
Discrete numbers These are also called discrete values. These refer to distinct, separate numerical values which have fixed gaps between them and cannot be divided into arbitrary intermediate fractions. They are got by counting rather than measuring.
Discrete observation – It is a data point or measurement which takes on only separate, distinct, and countable values rather than a smooth range of numbers. These observations fall into specific categories or fixed whole units where no intermediate fractional values exist between neighbours.
Discrete parts – These are separate, individual components which perform a single, distinct function. They cannot be broken down into smaller units without losing their identity. They serve as the basic building blocks for more complex systems or assemblies across electronics and manufacturing.
Discrete phase space – It is a lattice or finite set of points representing position and momentum coordinates in a system, structured using finite fields or modular arithmetic rather than continuous real numbers. It serves as a framework for finite quantum systems and discrete-variable quantum mechanics.
Discrete place – It means a specific, separate, and distinct location or position which stands apart from other areas. It refers to an isolated or demarcated spot rather than a continuous or connected space. Discrete places are the components in a hybrid Petri net model which represent specific states or conditions within a system.
Discrete process – It is a type of process where a specified quantity of material moves as a unit (part or group of parts) between work stations and each unit maintains its unique identity.
Discrete random variable – It is a value from a random event which can be counted as separate, distinct whole numbers or items. It has clear gaps between each possible number, unlike continuous measurements like weight or time. Common examples include rolling a die.
Discrete sensor – It is a device which provides a binary, on / off or true / false output signal rather than a continuous range of values. It indicates only two distinct states, such as present or absent, open or closed, or high or low, when a specific physical threshold or setpoint is reached.
Discrete sequence – It is an ordered list of numbers or objects where the position of each item matters. Mathematically, it is a function mapping a set of integers (like natural numbers) to a set of values. Unlike sets, order matters and items can repeat.
Discrete signal – It is a data stream defined only at separate, specific points in time or space rather than continuously. It functions like a sequence of individual snapshots instead of a smooth, unbroken wave, meaning no values exist between the measured points.
Discrete space – It is a basic mathematical space where all individual points are completely separate from each other. In this space, every single point stands alone as an open group, meaning you can draw a tiny circle around any point without touching any other point.
Discrete spectrum – It is a set of distinct, separate values with gaps between them, rather than a smooth, unbroken range. In physics and chemistry, it frequently appears as specific lines of light emitted or absorbed by atoms when electrons jump between fixed energy levels.
Discrete state – It is a specific condition or value in a system which can only take on distinct, separate, and fixed possibilities rather than a smooth range of numbers. Examples include a light switch being on or off, a valve being open or closed, or a counter holding an integer value.
Discrete state control – It is a method where a system manages equipment using distinct, fixed conditions (like on / off, open / closed, or true / false) and moves through a logical sequence of events rather than smooth, continuous adjustments. It is widely used in automation and manufacturing.
Discrete symbol – It is a distinct, separate character or value used in mathematics, logic, and computing to represent a specific, countable item, state, or operation rather than a continuous range.
Discrete system – It is a system where variables change only at separate, distinct points in time or take on a countable, specific set of values. It contrasts with continuous systems, which flow smoothly without interruption.
Discrete-time algorithm – It is a step-by-step computational procedure which operates on data sampled or updated at distinct, separated moments in time rather than in a continuous flow. These algorithms process indexed sequences like ‘x(n)’, forming the core of digital control, signal processing, and embedded systems.
Discrete-time case – It refers to a modelling or analysis scenario where time is split into separate, distinct steps or clock ticks rather than flowing smoothly. Systems change values only at these specific points.
Discrete-time control – It is a method where a digital processor or computer manages a physical system by reading data and updating control signals at fixed, periodic clock intervals rather than continuously.
Discrete-time Fourier series – It is a mathematical tool which represents a discrete-time, periodic signal as a finite weighted sum of harmonic complex exponentials.
Discrete-time Fourier transform – It is a transform-pair relationship between a discrete-time signal and its continuous-frequency transform, used for analyzing and designing discrete-time systems. It produces a continuous-frequency spectrum which is periodic with a period of 2-pi, representing the frequency content of the signal.
Discrete-time Lyapunov equation – it is a matrix equation to test the stability of discrete linear systems. It is written as ‘A to the power ‘T’ x P x A – P = -Q’, where ‘A’ is the system matrix, \’P’ is the unknown symmetric matrix, and ‘Q’ is a chosen positive definite matrix. A to the power ‘T’ is the transpose of the system matrix ‘A’.
Discrete-time signal – It is a signal represented as a time series of samples taken at regular intervals.
Discrete-time system – It is a mathematical rule or physical device that takes a discrete-time input signal sequence and transforms it into a discrete-time output signal sequence. It operates at specific, separate time steps (indexed by integers n) rather than over a continuous flow of time.
Discrete values – These are distinct, separate numerical or logical steps which can only take specific, countable quantities or fixed states (such as integers or on / off binary choices) with absolute gaps in between, rather than a smooth, unbroken range of fractions or decimals.
Discrete variable – A set of data is discrete if the values belonging to it are distinct, i.e., they can be counted. Examples are the number of children in a family, the number of rainy days in the month, or the length (in days) of the longest dry spell in the growing season. A discrete variable is measured on the nominal or ordinal scale, and can assume a finite number of values within an interval or range. Discrete variables are less informative than are continuous variables.
Discrete white spots – These are macro-segregation defects found mainly in vacuum-melted super-alloys. They appear as bright, solute-lean regions depleted of hardening elements like niobium or titanium. They typically occur when solid metal pieces (like shelf or crown fragments) fall into the molten pool and fail to dissolve completely.
Discrete Wigner function – It is a quasi-probability distribution which maps finite-dimensional quantum states (qudits, spin systems) onto a discrete phase-space grid. It adapts the continuous Wigner function for quantum information and finite Hilbert spaces, frequently using mutually unbiased bases (MUBs) to mirror marginal properties.
Discretionary dependency – It is the preferred way to sequence activities when there is no logical limitation on how they are to be ordered.
Discretization – It is the process of turning smooth, continuous data, equations, or physical spaces into separate, distinct, and countable pieces. It lets computers and mathematical formulas process complex, real-world information by breaking it into manageable steps or categories.
Discretization error – It is the difference between the exact analytical solution of a continuous mathematical model and the numerical approximation obtained by dividing the continuous domain into a finite number of discrete points, intervals, or elements.
Discretization scheme – It is a mathematical method used to turn continuous models, variables, or equations into discrete, individual parts. This process lets computers and numerical analysis solve complex differential equations and process continuous data.
Discretized equation – It is an algebraic equation or system of equations which changes a continuous mathematical model, such as a differential equation, into a discrete form which a computer can solve using numerical methods.
Discretized form – It is the representation of continuous mathematical expressions, models, or data as distinct, finite, individual elements or points. This conversion makes complex continuous systems solvable using computers and numerical methods.
Discretized momentum equation – It is the numerical, algebraic approximation of the continuous fluid momentum conservation law (like the Navier-Stokes equations). It converts differential equations into discrete algebraic relations solved at specific grid points or control volumes via computational fluid dynamics (CFD).
Discriminant function – It is frequently called a discrimination function. It is a mathematical formula used in statistics and machine learning to assign an object, event, or data point to one of several predefined groups or classes. It works by taking a set of input variables and calculating a score that dictates group membership.
Discrimination function – It is a mathematical construct derived from known group data which facilitates the clear differentiation of group characteristics, enabling the classification of new data based on established criteria.
Discriminator – It is a component, circuit, or algorithm designed to distinguish between different signals, objects, or data. Its main function is to evaluate input and classify whether it belongs to a specific category or differs from a reference standard.
Discriminator model – It attempts to differentiate pictures as either authentic or false while training it turns into better at revealing that separation. It takes a model as input (genuine or created) from the space and presents a parallel class mark of genuine or produced. The genuine model originates from the preparation dataset. The discriminator is a typical classification model. The discriminator model is disposed of as interest on the generator after the preparation procedure.
Disc segment – It is also called a circular segment. It is a region of a disc bounded by a chord and the corresponding arc of the circle. It is essentially a portion of a disc which is ‘cut off’ by a straight line (the chord).
Disc shape – It refers to a circular, flat, or cylindrical 3D geometry where the diameter is considerably larger than its thickness. Discs are fundamental to mechanical and structural design, defined mainly by their outer radius, inner radius (in the case of annular discs), and variable cross-sectional profiles. Discs are fundamental geometric parts designed to handle heavy compressive forces, torsion, or rapid rotation.
Disc spring – It is a spring washer with a conical shape. This shape gives the spring washer its flexible effect. Disc springs are also called Belleville-spring washers and conical spring washers. The properties of the disc spring make it unique in applications where space is limited – but where high force is wanted.
Disc stack – It is a set of cone-shaped metal plates nested closely together inside a high-speed industrial centrifuge. It splits a liquid mixture into several thin layers, using strong spinning forces to rapidly separate tiny solid particles or mixed liquids of different weights.
Disc stack centrifuge– It is a high-speed industrial machine which uses a vertical column of close-fitting, cone-shaped metal plates, called a disc stack, inside a spinning bowl to separate solids and liquids, or two liquids with different densities, by multiplying the effect of gravity through centrifugal force.
Disc tensioner – It is a mechanical device which controls and regulates the tension of a flexible linear material, such as wire, by passing it between two flat, circular discs pressed together by a spring or weight. Friction between the flat faces of the discs creates a steady retarding force on the moving material.
Disc test samples – These refer to circular, flat test pieces used to evaluate specific mechanical and surface properties. The disc format is predominantly used in pin-on-disc testing for wear resistance, Brazilian disc testing for indirect tensile strength, and small punch (SP) testing for localized material strength.
Disc turbine – It is a bladeless centripetal turbine which uses closely spaced, parallel flat discs. In industrial mixing, it refers to a circular disc impeller used for gas dispersion.
Disc, turbine – A turbine disc is a machined forging which can include an integral shaft or a flange for shaft attachment, featuring provisions for the attachment of turbine blades and designed to manage heat conduction by allowing cooling air to flow across its surfaces.
Discussion – It is an analytical evaluation which interprets data, validates design choices, and measures project feasibility. It is the technical section of a report or process where engineers analyze results, compare them to constraints, and explain real-world significance to support design, software, or construction decisions.
Dishing – It is forming of a shallow concave surface, the area which being large compared to the depth. These are (i) an edge dislocation which corresponds to the row of mismatched atoms along the edge formed by an extra, partial plane of atoms within the body of a crystal, and (ii) a screw dislocation which corresponds to the axis of a spiral structure in a crystal, characterized by a distortion that joins normally parallel planes together to form a continuous helical ramp (with a pitch of one interplanar distance) winding about the dislocation. Most prevalent is the so-called mixed dislocation, which is an combination of an edge dislocation and a screw dislocation.
Disincentive – It is a deterrent, a factor, penalty, or structural hurdle designed to discourage individuals or systems from taking a specific action. Disincentives act as deliberate friction or negative feedback to prevent unwanted behaviours, ensure compliance with standards, and optimize system safety.
Disinfection – It is a physical or chemical process which kills or removes harmful germs, bacteria, viruses, and fungi from non-living objects and surfaces. It lowers the number of these tiny life forms so they do not cause disease, though it may not destroy all hard-to-kill bacterial spores.
Disinfection process – It is the elimination of micro-organisms to levels which are not harmful to health, achieved through methods such as cleaning, chemical treatment, or heat application. This process does not typically eliminate bacterial spores, which need sterilization for complete removal.
Disintegration – It is the reduction of massive material to powder.
Disjoining pressure – It is the force per unit area which arises within a thin fluid film (like a liquid layer between two surfaces) because of the inter-molecular and surface forces. It equals the difference between the pressure inside the thin film and the pressure of the bulk phase.
Disjoint sets – These refer to subsets within a network which do not share any common elements or active nodes. In the context of sensor networks, these sets can be maximized to improve network life-time by scheduling them to operate successively while minimizing the number of active sensor nodes.
Dislocation – It is a linear imperfection in a crystalline array of atoms. The two basic types recognized are (i) an edge dislocation which corresponds to the row of mismatched atoms along the edge formed by an extra, partial plane of atoms within the body of a crystal, and (ii) a screw dislocation which corresponds to the axis of a spiral structure in a crystal and is characterized by a distortion joining normally parallel lines together to form a continuous helical ramp (with a pitch of one inter-planar distance) winding about the dislocation. A mixed dislocation, which is any combination of a screw dislocation and an edge dislocation, is prevalent.
Dislocation annihilation – It is the process where dislocations, linear defects in a metal’s crystalline structure, meet and cancel each other out. This reduces overall dislocation density and relieves the internal strain energy stored during deformation.
Dislocation arrangement – It refers to the spatial distribution and geometric organization of linear crystalline defects (dislocations) within a metal’s crystal lattice. This structure directly dictates a metal’s mechanical properties, including yield strength, ductility, and work hardening.
Dislocation behaviour – It refers to the movement and interaction of dislocations within a material, which influences considerably macroscopic plastic response and mechanical behaviour, as described through models which correlate dislocation density, strain rate, and applied stress.
Dislocation cells – These are tiny, nearly defect-free regions within a metal grain which are separated by dense tangles of linear crystalline defects, known as dislocations. They form during plastic deformation (like work hardening) as a metal’s crystal lattice attempts to reorganize and reduce its stored energy.
Dislocation climb – It is a mechanism which allows an edge dislocation to move perpendicular to its slip plane. This non-conservative motion relies on the diffusion of point defects (vacancies or interstitial atoms) through the crystal lattice, making it highly dependent on high temperatures. The climb process occurs in two main directions, driven by the presence or absence of atoms in the dislocation’s extra half-plane. These directions are positive climb (climb up) and negative climb (climb down).
Dislocation content – It refers to the local state of a crystal structure quantified by its dislocation density, measuring the total length of dislocation lines per unit volume. It dictates how a material deforms and gains mechanical strength under stress.
Dislocation core – It is the central, highly distorted region of a crystal defect where standard linear elasticity breaks down. It is only a few atoms wide and features severely displaced bonds. This specific region determines how easily a metal can plastically deform (bend or stretch).
Dislocation-core diffusion-controlled processes – These processes refer to high-temperature or high-stress material behaviours where the overall rate of atomic transport is governed by the rapid diffusion of atoms along the highly distorted centres of crystalline defects.
Dislocation-core diffusion-controlled climb – It is a high-temperature deformation mechanism. An edge dislocation climbs out of its slip plane by absorbing or emitting point defects. When this process relies mainly on the rapid transport of atoms or vacancies along the highly disordered centre of the dislocation, it is considered core-diffusion controlled.
Dislocation-core diffusion-controlled climb by edge dislocations – It is a high-temperature mechanism where an edge dislocation moves out of its slip plane. It achieves this by absorbing or emitting point defects (vacancies or interstitials) exclusively along the highly distorted path of its core.
Dislocation creep – It is the time-dependent permanent deformation of a material under a constant applied stress, typically at high temperatures (above 0.4 – 0.5 of the absolute melting point). It is driven by the motion, generation, and annihilation of line defects in a crystal lattice, known as dislocations. It is the inelastic deformation of materials driven by the movement of dislocations in the crystal lattice, which can occur through glide and climb mechanisms, particularly at elevated temperatures and under sufficiently high stresses. This process is characterized by a power-law dependence on stress and involves overcoming obstacles such as other dislocations or impurities.
Dislocation defect – It is a linear or one-dimensional crystal defect where atoms are misaligned. This irregularity allows metals to bend and shape without breaking and without it, metals are extremely brittle. Understanding how these defects move is the basis for strengthening metals like steel or aluminum.
Dislocation density – It is the total length of dislocation lines per unit volume, or the number of dislocation lines that cut through a unit cross-sectional area.
Dislocation distribution – It describes how linear defects (dislocations) are spatially arranged throughout a metal’s crystal lattice. It dictates important material properties like strength, hardness, and ductility by influencing how easily the metal deforms under stress.
Dislocation dynamics – It is the study and physical or computational modelling of the collective movement, evolution, and interaction of crystal line defects (dislocations) which govern plastic deformation in crystalline materials.
Dislocation emission – It is the process where a crystal lattice defect (a dislocation) is newly created and pushed out from a high-stress concentration site, such as a crack tip, grain boundary, or surface, into the material’s interior during plastic deformation.
Dislocation etching – It is the etching of exit points of dislocations on a surface. It depends on the strain field ranging over a distance of several atoms. Crystal figures (etch pits) are formed at exit points. For example, etch pits for cubic materials are cube faces.
Dislocation flow – It refers to the movement of line defects (dislocations) through a crystal lattice. When a metal is subjected to applied shear stress, these dislocations move, causing atomic planes to slide over one another. This collective movement is the fundamental mechanism of plastic deformation. Dislocation flow occurs mainly through two mechanisms namely dislocation glide (conservative motion), and dislocation climb (non-conservative motion).
Dislocation formation – It is the process where line defects or irregularities develop within the crystal lattice of a solid material. This typically happens when mechanical stress exceeds a material’s elastic limit, or during thin-film growth because of the lattice mismatches between the growing layer and the underlying substrate.
Dislocation glide – It is the main mechanism by which crystalline materials undergo plastic deformation. It occurs when an applied shear stress causes a line defect (dislocation) within the crystal lattice to move along a specific crystallographic plane.
Dislocation glide-climb – It refers to a high-temperature deformation process where crystal line defects (dislocations) alternately move along their slip planes (glide) and shift to parallel planes (climb) to bypass microstructural obstacles. This combined mechanism is the main driver behind dislocation creep in crystalline materials. The mechanism operates through two distinct but sequential steps namely dislocation glide (slip) and dislocation climb.
Dislocation glide creep – It is a time-dependent plastic deformation mechanism in crystalline materials where dislocations (crystal defects) move along their specific slip planes. Driven by applied stress, this fast, low-energy motion causes progressive strain over time without necessarily altering the plane of the dislocation.
Dislocation half-loop – It is a U-shaped or semi-circular dislocation segment which nucleates at a crystal’s free surface (or interface) and extends into the bulk, with both of its end-points terminating back at that same surface.
Dislocation interaction – It is how the elastic strain fields of line defects (dislocations) inside a crystal lattice affect each other. When line defects cross or approach one another, their combined stress fields either attract or repel. This blocks further slip, raises the material’s yield strength, and causes work-hardening.
Dislocation junction – It is a stable linear defect formed when two moving dislocations from different slip systems intersect and react with each other. This reaction creates a new segment with a combined Burgers vector.
Dislocation line – It is a one-dimensional (linear) crystallographic defect within a crystal lattice. It represents the boundary dividing a slipped (deformed) region from an unslipped region of the material. The movement of these lines under applied stress is the main mechanism which allows metals to undergo plastic deformation.
Dislocation loop – It is a closed, continuous boundary within a crystal lattice which separates an area where the material has slipped from an area where it has not. Since dislocation lines cannot simply end inside a perfect crystal, they are to terminate at grain boundaries, free surfaces, or form a closed loop. Dislocation loops fall into two main categories namely (i) shear (glide) loops which are formed when shear stress is applied to an existing dislocation line (frequently multiplying through the Frank-Read mechanism), and (ii) prismatic loops which are formed by the clustering and condensation of point defects, such as vacancies or interstitial atoms (extra atoms squeezed into the lattice). This is highly common during quenching, rapid cooling, or radiation exposure.
Dislocation mechanism – It refers to the processes involving the motion and interactions of dislocations, which are critical to understanding deformation and failure in ductile metallic systems. These mechanisms are influenced by factors such as grain size and dislocation density, particularly in nanograined metals.
Dislocation models – These are theoretical and computational frameworks used to explain how materials deform under stress. They describe how microscopic line defects (dislocations) in a crystal lattice generate, move, and interact, directly dictating macroscopic physical properties like yield strength, ductility, and hardness. The application of dislocation models explains why metals are far softer than ideal atomic calculations predict, revolutionizing how engineers understand material strengthening.
Dislocation motion – It is the shifting of line defects (dislocations) through a crystal lattice. This movement happens when a force breaks and reforms atomic bonds. It allows metals to change shape permanently at low stress levels without breaking.
Dislocation movement – It refers to the shifting of linear crystalline defects (dislocations) within a metal’s atomic lattice when subjected to stress. This process allows atomic layers to easily slide over one another sequentially, serving as the primary mechanism for plastic deformation in metals. Since a dislocation needs the breaking and reforming of only a few atomic bonds at a time, this movement needs vastly less energy than trying to shear an entire plane of atoms simultaneously. Dislocation motion normally falls into two main modes namely glide (or slip) and climb.
Dislocation pile-up – It is a group of line defects (dislocations) which jam together behind an unyielding barrier inside a crystal lattice. This cluster forms when applied stress pushes the defects along a slip plane until they hit an obstacle they cannot cross.
Dislocation-pinning – It is a mechanism where internal obstacles in a metal’s crystal lattice trap, restrict, or ‘pin’ the movement of dislocations. Since plastic deformation (the shaping or bending of metals) relies on these line defects sliding past one another, pinning them forces the metal to resist deformation, hence increasing its overall strength and hardness.
Dislocation-precipitate reactions – These reactions refer to how mobile dislocations, atomic-scale structural defects, interact with microscopic, second-phase particles (precipitates) distributed within a metal’s crystal matrix. These reactions are the main mechanism driving the strength and hardness of heat-treatable alloys. When an external stress is applied, plastic deformation occurs as dislocations glide across the metal’s crystalline lattice. Precipitates act as physical road-blocks which impede this movement. The exact reaction which occurs depends on the size, spacing, and coherency of the precipitates with the surrounding metal matrix.
Dislocation recovery – It is an annealing process where a plastically deformed metal reduces its stored internal energy. It achieves this by eliminating and rearranging crystalline defects, mainly dislocations. This restores physical properties (such as electrical conductivity) while minimally altering the original deformed grain structure. The main mechanisms for this process act to reduce overall dislocation density and minimize localized stress fields within the crystal lattice.
Dislocations, crystals – Dislocations in, crystals are defined as line defects which play an important role in the plastic flow of crystalline materials, acting as sources of long-ranged elastic stresses and strains. These dislocations are integral to understanding the mechanical properties of crystals, particularly in the context of plastic deformation and the discrepancies between theoretical and experimental strength.
Dislocation slip – It is the fundamental mechanism of plastic (permanent) deformation in crystalline materials. It occurs when an applied shear stress causes lines of atomic defects (dislocations) to move or glide across specific crystallographic planes.
Dislocation structures – These refer to the arrangements of unpaired dislocations and dislocation walls within a material, which influence the material’s plastic deformation and can be characterized through techniques such as X-ray micro-diffraction.
Dislocation velocity – It is the speed at which line defects (dislocations) move through a metal’s crystal lattice when subjected to an external force. It is the main microscopic mechanism which governs plastic deformation (permanent yielding and shaping) and work-hardening in metals.
Dislocation walls – These are dense, two-dimensional boundaries formed when line defects (dislocations) in a crystal lattice arrange and self-organize into structured, planar patterns. These walls divide the metal’s crystalline grains into tiny, semi-ordered regions called sub-grains or cell blocks.
Disordered structure – It is the crystal structure of a solid solution in which the atoms of different elements are randomly distributed relative to the available lattice sites.
Dislocation sub-structure – It is the organized arrangement, density, and spatial distribution of linear crystal defects (dislocations) inside a metal or crystalline material. As a material undergoes plastic deformation, these line defects multiply and tangle. They group into walls or cells that partition the crystal grains into smaller micro-domains.
Dislocation velocity – It is the speed at which a crystal lattice line defect (dislocation) moves through a metal or ceramic when an external stress is applied. It dictates how plastic deformation and yielding happen in crystalline solids.
Dislocation yield strength – It is the critical level of stress needed to initiate the movement of dislocations (line defects) through a crystalline material’s atomic lattice. When applied stress overcomes this internal resistance, permanent (plastic) deformation begins.
Dismantlers – Dismantlers are people, tools, or systems that safely take apart machines, structures, or industrial plants. Their main goal is to recover valuable parts, clear hazardous materials, or prepare heavy items for recycling and waste management.
Disordered alloy – It is a solid solution where constituent atoms occupy lattice sites randomly with no long-range periodic super-lattice, or show complete amorphous structural randomness. Unlike ordered alloys, every atomic plane is statistically identical, yielding unique mechanical, thermal, and electronic traits.
Disordered carbon – It describes carbon materials which lack long-range crystalline order, featuring a non-periodic, irregular arrangement of sp2 (graphitic) and sp3 (diamond-like) hybridized carbon bonds. This category includes amorphous carbon, hard carbon, and soft carbon, which are widely engineered for energy storage, electronics, and structural applications.
Disordered phase – It is a state of matter where atoms, ions, or molecules occupy crystal lattice sites in a random or irregular distribution rather than a strict periodic pattern. This state is normally driven by high thermal energy, which increases configurational entropy.
Disordered structure – It is a material or system which lacks a regular, repeating periodic pattern in the arrangement of its atoms, molecules, or components. Instead of a neat crystal lattice, it features an irregular, random, or amorphous lay-out which is intentionally engineered to optimize mechanical, thermal, or electrical traits.
Disordering – It means forming a lattice arrangement in which the solute and solvent atoms of a solid solution occupy lattice sites at random.
Disorder phenomenon – It refers to disruptions or irregularities in the regular arrangement of atoms, ions, or molecules within a crystal lattice or material system. Rather than being completely random or flawed, this controlled or natural deviation dictates crucial thermal, mechanical, and electronic properties.
Disparity – It refers to substantial differences in chemical, physical, or mechanical properties between different metals or microstructural components being joined, alloyed, or analyzed.
Disparity estimation – It refers to quantifying the variance or mismatch between predicted processing behaviours (such as metal recovery or hardness) and actual plant performance, or between different mineral blocks in an ore body. It helps optimize mineral processing and reduce operational risks. It is also the computer vision process of calculating the horizontal distance or shift between matching pixels in a pair of stereo images. It computes the horizontal pixel distance between matching points in a stereo camera pair. This measurement creates a disparity map which helps systems calculate physical depth, allowing robots, autonomous cars, and 3D scanners to see and map distances in their environment.
Disparity map – It is a digital image that stores the apparent horizontal pixel shift (displacement) of objects between a pair of stereo camera images. It is used to calculate depth and reconstruct 3D environments.
Dispatchable unit – It is a power generation plant or storage system whose output can be turned on, turned off, increased, or decreased on demand by grid operators to match real-time electricity and maintain system stability.
Dispatch cost – It refers to the incremental or variable cost (such as fuel and maintenance) needed to generate an additional megawatt-hour (MWh) of electricity from a specific power unit. It forms the baseline for economic dispatch, which schedules plant outputs to meet total demand at the lowest overall cost.
Dispatcher – It is a system, software module, or coordinator which manages task requests. It evaluates available resources, such as field personnel, server processors, or vehicle fleets, and assigns them efficiently to specific jobs to optimize performance, routing, or execution order.
Dispatch hour – It is a specific one-hour time block during which power generators are scheduled and instructed by a control centre to deliver a set quantity of electrical energy or capacity.
Dispatch instruction – It is a formal, real-time directive or set-point order issued by a system operator or controller to manage the active operation, power output, or execution flow of a specific resource, such as a power plant, manufacturing machine, or computer processor component.
Dispensing process – It is the controlled, precise application, metering, or deposition of fluid, viscous, or powdered materials onto a specific target, component, or assembly. It ensures exact volume, location, and repeatability for manufacturing operations.
Dispersal – It is the spread of a radioactive discharge in the environment.
Dispersant – It is a substance which disperses another substance in a medium, such as water, to form a colloidal solution, mainly by reducing adhesion between particles and preventing flocculation or agglomeration. Dispersants can be categorized into inorganic types, like silicates and alkali metal phosphates, and organic types, such as cellulose derivatives and polycarboxylates.
Dispersant additive – · In lubrication technology, it is an additive capable of dispersing cold oil sludge.
Dispersant oil – It is a heavy-duty oil containing a dispersant additive.
Dispersed generation – It is also known as distributed generation. It is the practice of producing electricity using small-scale, localized facilities connected directly to the local distribution network close to where the power is consumed, rather than relying on massive, centralized power plants.
Dispersed phase – It is also a discontinuous phase. It refers to fine particles, precipitates, or second-phase constituents distributed uniformly throughout a primary metallic matrix (the continuous phase). It acts to strengthen the metal by restricting dislocation movement during deformation. It also refers to finely divided particles, droplets, or bubbles of one substance distributed throughout a different, continuous background medium. This distributed matter is the ‘guest’ suspended within the host medium and does not dissolve.
Dispersed shrinkage – It is frequently referred to as micro-shrinkage. It is a foundry casting defect where microscopic, isolated voids are scattered throughout a localized region of the metal. It happens when the natural volume reduction of molten metal during cooling outpaces the flow of liquid metal needed to fill the space. This defect predominantly occurs during ‘pasty solidification’, where a network of branching metal crystals (dendrites) blocks the channels, preventing liquid metal from reaching the final cooling areas.
Disperse dyes – These are non-ionic, synthetic organic colourants with low water solubility. They are engineered without ionizing groups and feature small molecular sizes designed to colour hydrophobic (water-fearing) polymer fibres like polyester, nylon, and acetate through an aqueous colloidal dispersion.
Dispersibility – It is the ability of a solid or liquid substance to break down and distribute itself uniformly as fine, individual particles or droplets throughout a continuous liquid or gas medium without immediately re-aggregating. This property governs material stability, manufacturing performance, and structural integrity.
Dispersing agent – It is a substance which increases the stability of a suspension of particles in a liquid medium by deflocculation of the primary particles.
Dispersing element – It is an optical component, such as a prism or a diffraction grating, which separates incoming poly-chromatic light into its individual constituent wave-lengths through refraction or diffraction. It serves as the core functional part of instruments like spectrographs, spectrometers, and monochromators.
Dispersion – It means breaking big particles into small particles and suspend them in water so that they can be removed by rinsing. Alkaline silicates and phosphates are beneficial for dispersion. In data analysis, dispersion is the way of spreading the variables around the central tendency. Common tools are range, variance, and the square root of the variance which is known as standard deviation. In statistical analysis, dispersion is the degree of scatter or concentration of observations around its centre or middle. It is normally measured as a deviation around some central value such as the mean, standard, or absolute deviation, or by an order statistic such as deciles, quintiles, and quartiles.
Dispersion capacity – It very frequently defines the maximum capability of an additive (such as a superplasticizer in concrete) to separate and distribute fine solid particles uniformly within a fluid medium, reducing water demand or viscosity while maintaining optimal workability.
Dispersion compensating fibre – It is a specialty optical fibre engineered with a high negative chromatic dispersion coefficient. It is deployed to counteract and neutralize the positive chromatic dispersion accumulated by light pulses as they travel through standard single-mode fibres (SMF) over long distances.
Dispersion compensator – It is a device or hardware module used in optical engineering and fibre-optic communication to correct chromatic dispersion. It fixes signal distortion and pulse broadening by applying opposite dispersion properties to restore the original shape of the light pulses.
Dispersion component – It is a device or material feature used to manage, control, or separate the different frequency or wavelength components of a signal (such as light waves in optics or pulses in transmission lines) to maintain data integrity and prevent distortion.
Dispersion contribution – It is a mathematical term in an equation of state (EOS) which accounts for attractive, non-polar intermolecular forces (London dispersion forces) between molecules. It corrects baseline repulsive models to accurately predict real fluid properties.
Dispersion curve – It is a graph which plots the relationship between wave frequency and wave speed, wave number, or phase velocity / group velocity. It shows how different frequency components of a wave travel through a continuous medium or structure at varying speeds.
Dispersion diagram – It is a graph which plots wave frequency against wave number. It shows how waves travel through a medium or periodic structure. Engineers use it to find allowed and forbidden frequencies, wave speeds, and band gaps in materials like meta-materials and photonic crystals.
Dispersion energy – It very frequently refers to London dispersion forces, weak, short-range attractive forces between atoms and molecules caused by random shifts in electron density. It can also describe the mechanical or shock-absorbing capacity of a material to spread out impact energy.
Dispersion equation – It is also called dispersion relation. It is a mathematical formula which connects the frequency of a wave to its wave-number or wave-length. It shows how fast different parts of a wave travel through a material or system.
Dispersion field – It is frequently called a dispersion trench or drain field. It is a designated sub-surface area where treated effluent or storm-water run-off is distributed and spread across a wide area to safely percolate into native granular soils without concentrated erosion.
Dispersion-flattened fibre – It is a specialized optical fibre engineered to maintain very low chromatic dispersion across a wide range of wave-lengths. It achieves this by tailoring the refractive index profile to cancel out material dispersion with wave-guide dispersion, preventing data pulses from spreading out in multi-frequency systems.
Dispersion forces – These are the weakest intermolecular forces. They arise when electrons in an atom or molecule momentarily group to one side, creating a temporary (instantaneous) dipole. This shifting charge then distorts the electrons of nearby molecules, causing a brief attractive electro-static interaction.
Dispersion hardening – It is strengthening of a metal or alloy by incorporating chemically stable sub-micron size particles of a non-metallic phase which impede dislocation movement at high temperature.
Dispersion of a distribution – It is the degree of spread shown by a variable’s values, typically assessed with the standard deviation.
Dispersion medium – It is the continuous back-ground phase in a heterogeneous mixture where fine particles, droplets, or gas bubbles (the dispersed phase) are distributed. It acts as the carrier matrix supporting these particles.
Dispersion polymerization – It is a single-step, heterogeneous process where soluble monomers and initiators form a uniform solution in a solvent, but the resulting polymer is insoluble. Stabilizers prevent clumping, creating uniform micron-sized polymer particles for coatings, and resins.
Dispersion quality – It measures how uniformly solid particles, droplets, or fibres are broken down and spread through a liquid, gas, or solid matrix. High dispersion quality means minimal clustering (agglomeration) and consistent material, mechanical, or optical properties throughout the final product.
Dispersion relation – It is a mathematical equation which connects a wave’s angular frequency to its wave-number or wave vector. It shows how wave speed changes across different frequencies or wavelengths as a wave moves through a specific medium or structure.
Dispersion relationship – It refers to the unique relationship between angular frequency, wave-number, and depth for linear waves, allowing for the determination of one quantity when the other two are known.
Dispersion-shifted fibre – It is a single-mode optical fibre engineered to move its zero-dispersion wave=length from the natural 1.3 micro-meters region to the 1.55 micro-meters minimum-loss window. This design minimizes chromatic distortion and signal loss simultaneously over long distances.
Dispersion slope compensation – It is an engineering method used in optical fibre networks to match and cancel out the varying chromatic dispersion values across different wave-length channels. It ensures that all data channels in a multi-wavelength system are equally corrected to prevent signal distortion.
Dispersion stability – It is the ability of a mixed system, where tiny particles, droplets, or bubbles stay spread out in a fluid, to resist change and keep its uniform structure over time.
Dispersion-strengthened material – It is a metallic material which contains a fine dispersion of non-metallic phase(s), such as alumina, magnesia, silica, cadmium oxide, thorium di-oxide, yttrium oxide, zirconium oxide singly or in combination, to increase the hot strength of the metallic matrix. Examples include dispersion-strengthened copper (alumina) used for welding electrodes, silver (cadmium oxide) used for electrical contacts, and nickel-chromium (yttrium oxide) superalloys used for gas turbine components.
Dispersion strengthening – It is the strengthening of a metal or alloy by incorporating chemically stable sub-micron size particles of a non-metallic phase which slow down dislocation movement at high temperature.
Dispersion system – It is a heterogeneous mixture where fine particles, droplets, or gas bubbles (the dispersed phase) are distributed throughout a continuous, bulk material (the dispersion medium). The two phases can be combinations of solids, liquids, or gases.
Dispersion trench – It is an excavated, gravel-filled underground channel designed to spread liquid waste or storm-water run-off evenly across a wide soil area. It prevents concentrated erosion and promotes safe natural absorption into the ground.
Dispersion wave-length – It is frequently referred to as the zero-dispersion wave-length (ZDW). It is the specific light wave-length where different wave-length components of a signal travel at the exact same group velocity, eliminating chromatic pulse distortion.
Dispersive channel – It is a communication medium which causes a transmitted signal to spread out in time, frequency, or space. This spreading happens since different components of the signal travel at different speeds or take multiple paths, which distorts the data and causes overlap.
Dispersive transport – It is the macroscopic spreading of mass, heat, or particles as they move through a medium (like porous soil, packed-bed reactors, or pipelines). It happens since non-uniform flow paths and varying velocities stretch and mix the substance over time.
Dispersoids – These are tiny, finely distributed second-phase particles embedded within a metal matrix. Ranging from 0.1 micro-meter to 1 micro-meter in size, they are thermodynamically stable and do not dissolve into the base metal, playing a key role in micro-structure control and strengthening. These are finely divided particles of relatively insoluble constituents visible in the micro-structure of certain metallic alloys.
Displaced fluid – It is the volume or mass of liquid or gas which is pushed aside when an object is immersed in it, or when one fluid is forced out of a system by another fluid. Displaced fluid refers to the fluid which is moved or replaced by another fluid during a displacement process in reservoirs, where differences in density between the fluids significantly influence the stability and efficiency of the displacement.
Displacement – It is the distance that a chosen measurement point on a cracked sample displaces normal to the crack plane as the crack grows. In case of fluid mechanics, displacement occurs when an object is largely immersed in a fluid, pushing it out of the way and taking its place. The volume of the fluid displaced can then be measured, and from this, the volume of the immersed object can be deduced, The volume of the immersed object s exactly equal to the volume of the displaced fluid. A displacement is also a vector whose length is the shortest distance from the initial to the final position of a point undergoing motion. It quantifies both the distance and direction of the net or total motion along a straight line from the initial position to the final position of the point trajectory.
Displacement amplitude – It is the maximum distance a vibrating structure, machine part, or wave particle moves away from its centre rest (equilibrium) position during a single cycle of oscillation. It is measured in units of length, such as meters or millimeters.
Displacement angle – In filament winding, it is the advancement distance of the winding ribbon on the equator after one complete circuit.
Displacement approximation – It is a method used to estimate how a structure or material deforms under load. Instead of finding exact movements at every single point, it uses simple mathematical functions (like polynomials) linked to specific reference points called nodes. This concept is fundamental to the Finite element method (FEM).
Displacement blower – Positive displacement blower traps a fixed volume of air or gas at the intake and forces it out against system pressure. These constant-volume machines typically deliver pressures up to 0.1 mega-pascals and maintain steady flow rates regardless of system resistance.
Displacement boundary condition – It is also called a Dirichlet or essential boundary condition. It fixes the exact movement or position (u = u-bar) at specific surfaces, edges, or nodes of a physical system. It stops rigid-body motion and defines how a model connects to its environment.
Displacement component – It is an individual directional value (u, v, w or u1, u2, u3) of a displacement vector. It measures the exact change in position of a point or a node along a specific Cartesian coordinate axis (x, y, z) when a structure or material deforms under a load.
Displacement compression – It consists of reduction of the air volume. Positive displacement machines use reciprocating piston, rotary screw, or vane types to produce air compression. Screw, reciprocating, and vane compressors are positive displacement machines.
Displacement constraint – It is a boundary condition or structural limitation which restricts or specifies the translational or rotational movement of a point, surface, or node in a mechanical system or finite element analysis (FEA) model.
Displacement-controlled loading – It is a testing and analysis method where the movement or deformation (displacement) of a structure or material samples is fixed or increased by set quantities, and the resulting force or load is measured as the dependent variable.
Displacement-controlled test – It is a method where the machine moves a part or sample by a set distance at a steady rate. The test measures the load or force which changes as the material bends, stretches, or breaks.
Displacement coordinate – It defines the linear or angular distance a point or node moves from its original, undeformed reference position along a specific axis within a designated coordinate system.
Displacement craft – It is a type of vessel which moves by pushing aside a volume of water equal to its own total weight. It relies entirely on buoyancy rather than dynamic lift to stay afloat, meaning its hull stays partially submerged at all speeds.
Displacement current – It is the effect of a time-varying electric field, which induces a magnetic field just as the motion of electrical charges does.
Displacement curve – It is a graph showing how an object’s change in position, structural movement, or material deformation relates to another variable like time, force, or draft.
Displacement diagram – It is a graph which plots the movement (displacement) of a mechanical part, such as a cam follower, against time or the rotation angle of a driving component. It helps engineers visualize and design smooth machinery motion.
Displacement efficiency – It is the fraction of movable oil recovered from the specific pore spaces contacted or ‘swept’ by a displacing fluid, such as water or gas. It measures microscopic, pore-level extraction effectiveness, independent of how much total reservoir volume the fluid reaches.
Displacement equation – It defines the net change in position of an object or structural node. In kinematics, it is calculated as final position minus initial position ‘delta x = xf – xi’. Under constant acceleration, it is expressed as ‘s = ut + 1/2 a x t-square, where ‘s’ is displacement, ‘u’ is initial velocity, ‘a’ is acceleration, and ‘t’ is time.
Displacement factor – It is also called displacement power factor (DPF). It is the cosine of the phase angle (phi) between the fundamental voltage wave-form and the fundamental current wave-form in an AC (alternating current) circuit. It quantifies the quantity of reactive power present at the base frequency.
Displacement field – It is a displacement field which describes the movement of atoms or points in a metallic crystal lattice from their original, stress-free positions to new locations after being subjected to mechanical stress, plastic deformation, or phase transformations. It is a function which locates the current position of material points relative to their reference positions, represented mathematically as ‘u = x – X’, where ‘x’ is the deformed position and ‘X’ is the undeformed position.
Displacement formulation – It is an analytical approach where structural displacements are solved as the primary unknown variables before calculating strains and stresses.
Displacement function – It is a mathematical expression which maps the change in position of a material point or a structural node from its original, undeformed state to its new, displaced state.
Displacement gradient – It is a second-order tensor which measures how much the displacement of a material point changes with respect to its initial position. It describes local stretching, compression, and rotation within a deforming body.
Displacement increment – It is a small, discrete change in the position or deformation of a structural node or material point during a single step of a non-linear numerical analysis, such as the finite element method.
Displacement jump – It is the sudden mathematical difference or discontinuity in the displacement field across a surface, interface, or crack. Instead of the material stretching smoothly, one side of the boundary moves to a distinctly different position than the other side.
Displacement line – It is also called displacement vector / curve. It represents the specific path or locus of points showing how much a structural element, machine part, or medium shifts from its original, undeformed position when subjected to loads, heat, or forces.
Displacement machine – It is a device which moves or compresses a fixed volume of fluid by trapping it within a closed chamber and using moving components like pistons, gears, or vanes to force it through the system.
Displacement measure – It defines the quantified change in position of an object, point, or structure relative to a reference starting point. It tracks linear, rotational, or angular movement using specialized contact or non-contact sensors to evaluate structural safety, mechanical deformation, and operational vibration.
Displacement measurement – It is the process of quantifying the change in position or directed distance of an object relative to a reference starting point. It tracks linear, rotational, or angular movement using specialized sensors to evaluate physical parameters like vibration, expansion, and deformation.
Displacement method – It is also called the stiffness method or equilibrium method. It is an analysis technique where joint displacements and rotations are the primary unknowns. After finding these values using equilibrium equations, engineers calculate internal forces and bending moments.
Displacement on demand – It is also known as cylinder deactivation or active fuel management. It is a technology which shuts off a portion of an engine’s cylinders during light-load operations (like highway cruising) to save fuel.
Displacement performance measure – It is a quantitative metric used to evaluate how far a system, structure, or joint deviates from a reference or neutral position. It calculates movement using relative spatial data to assess accuracy, structural integrity, or mechanical efficiency.
Displacement piles – These piles are driven piles. In the displacement piles, soil is displaced laterally when the pile is installed, hence, the soil gets densified. The installation can cause heaving of the surrounding ground. Pre-cast concrete pile and closed end pipe pile are high displacement piles. Steel H-piles are low displacement piles.
Displacement plot – It is a visual colour-coded map or graph showing how much a structure or model moves and deforms under applied loads, forces, or thermal changes. It highlights maximum and minimum positional shifts of nodes or elements.
Displacement power factor – It is the cosine of the phase angle (phi) between the fundamental frequency components of the voltage and current wave forms in an AC (alternating current) circuit. It measures the reactive power shift caused by linear inductive or capacitive loads, completely ignoring any harmonic distortion.
Displacement rate – It is the speed at which an object or material changes its position over time. It equals velocity in general mechanics, or the rate of deformation (combining creep, elastic, and plastic movement) in material testing and fluid volume displacement per cycle in hydraulic systems.
Displacement rate vector – It is the mathematical representation of how fast and in which direction a material’s internal points deform over time. It is the time derivative of the displacement vector.
Displacement reaction – It is a chemical process where a more active element pushes out a less active element from a compound. Engineers use these core oxidation-reduction reactions to extract pure metals, coat surfaces, and join heavy components.
Displacement relation – It is frequently called the strain-displacement relation. It is the mathematical formula which connects the physical movement (displacement) of material points in a body to the resulting deformation (strain). It forms the foundation of structural analysis and the finite element method.
Displacement relationship – It normally known as the strain-displacement relation. It is the mathematical link between how much a material moves (displacement) and how much it stretches or distorts (strain). It uses spatial derivatives to show how structural movement creates internal deformation.
Displacement response – It is the measure of how far and in what direction a structure or material moves from its original, resting position when subjected to an applied load, force, or dynamic event like an earthquake or vibration. It is the physical translational or rotational change in position of a point on a system under loading.
Displacement sensitivity – It measures how much a system’s output changes relative to a physical change in position or displacement. It is defined mathematically as the ratio of output change (delta output) to the input displacement change (delta x), representing the gain, resolution, or structural derivative (du / dp).
Displacement sensor – It is a device which measures the change in position or distance of an object relative to a reference point. It converts this physical movement into a proportional electrical signal, tracking linear or angular travel down to micro-meter or nano-meter precision.
Displacement step – It is a distinct incremental load or time phase where structural movement, deformation, or boundary shifts are solved and recorded. It defines how a system transitions from one positional state to the next under applied forces.
Displacement thickness – It is the distance that an external streamline is pushed away from a solid boundary. It compensates for the loss of mass flow rate caused by the slowing down of fluid inside the boundary layer.
Displacement-time – It refers to the relationship or graphical representation showing how an object’s position changes over a specific duration. The slope (gradient) of a displacement-time graph at any given point directly defines the object’s velocity.
Displacement transducer – It is an electro-mechanical device which converts mechanical motion, position, or distance changes (linear or angular) into a proportional electrical signal such as voltage, current, or frequency. It serves as a core feedback sensor in automated control, robotics, and testing machinery.
Displacement vector – It defines the magnitude and direction of the movement of atoms, or groups of atoms, from their original, undisturbed positions in a crystal lattice to their new positions during deformation, such as the movement of a dislocation. Displacement vectors are most famously represented by the Burgers vector, which measures the magnitude and direction of lattice distortion caused by a dislocation (a line defect in the crystal structure).
Displacement ventilation – It is an HVAC (heating, ventilation, and air conditioning) air distribution method that introduces cool, fresh air at low velocity near the floor. This dense air pools low and rises through natural thermal buoyancy when heated by occupants and equipment, pushing stale air and contaminants upward to high-level ceiling exhausts.
Displacement volume – It is also called swept volume. It is the total volume of fluid (air, gas, or liquid) pushed or swept by a moving part, such as a piston, plunger, or vane, inside a cylinder during one complete stroke or revolution.
Displacement work – It is also called PdV work, where ‘P’ is pressure, and ‘dV’ is the change in volume. It is the mechanical work done by or on a closed system when its boundary moves, causing a change in volume. It is normally visualized using a piston-cylinder assembly where gas expansion or compression moves the boundary.
Displacive transformation – It is a rapid, diffusion-less phase change where atoms shift cooperatively through small, coordinated movements to alter a material’s crystal structure without changing its chemical composition.
Display control panel – It is a visual interface, such as an HMI (human machine interface) touch screen, digital readout, or indicator board, housed within an enclosure which allows operators to monitor, manage, and interact with industrial processes, electrical systems, or machinery in real time.
Display data channel – It is a collection of protocols for digital communication between a computer display and a graphics adapter that enable the display to communicate its supported display modes to the adapter and that enable the computer host to adjust monitor parameters, such as brightness and contrast.
Display device – It is a device which displays data from an information system.
Display, function – Function displays refer to the screens or interfaces which present operational parameters and information related to equipment and systems, which can include dynamic or static data, quantitative or qualitative representations, and various forms of visual indicators such as graphs and numerical values.
Display functions – These functions refer to the specialized hardware interfaces or software systems which transform complex data into visual representations, allowing human operators to monitor and interact with system parameters. The concept of a display or function definition shifts between systemic, hardware, software, and industrial design frameworks.
Display model – It is a physical, non-functional 3D representation of an object used for exhibition, design evaluation, or education, or a conceptual framework mapping how electronic screens render visual data.
Display processor – It is a specialized hardware component or I/O (input/output) processor which converts digital graphics commands from the main CPU (central processing unit) into picture elements or analog signals for a screen. It relieves the central processor of intensive rendering tasks.
Display resolution – It is the number of tiny dots, called pixels, which make up the image on a screen. It is written as width by height. For example, 1,920 × 1,080 means 1,920 pixels wide and 1,080 pixels high. More pixels mean a sharper and clearer picture.
Display work-station – It is a high-performance computer terminal or system set-up featuring a high-resolution display monitor, keyboard, and mouse. It is engineered for professional, technical, or scientific tasks like 3D rendering, and computer-aided design (CAD), offering more power than a standard desktop.
Disposable battery – It is also called a primary battery. It is a single-use power cell designed to be thrown away after its chemical energy is fully used up. This battery cannot be recharged.
Disposability assessment – It is an advisory process) to provide advice on whether a proposed waste package is suitable for geological disposal.
Disposal – In the context of solid waste, disposal is the emplacement of waste in a suitable facility without intent to retrieve it at a later date. Retrieval can be possible but, if intended, the appropriate term is storage. Disposal can also refer to the release of airborne or liquid waste to the environment (i.e., emissions and discharges).
Disposal facility – It is a site or structure used to permanently contain, destroy, or discard waste so it remains isolated from the environment. These locations ensure that solid or hazardous materials are safely put into or onto land or water without intent for future recovery. it is also known as repository. It is a long-term radioactive waste storage facility.
Disposal option – It is a chosen method or alternative available for getting rid of, discarding, or transferring ownership of waste, assets, or property. It defines the specific path taken to discard physical refuse or divest from financial and corporate holdings.
Disposal technology – It refers to the scientific methods, engineered systems, and technical processes used to treat, neutralize, store, or permanently eliminate waste materials safely. It ensures discarded substances cause minimal harm to public health and the environment.
Disposal well – It is a deep well which is used for the disposal of liquid wastes.
Disproportional sound flow – In metal forming (specifically co-extrusion or co-drawing), it occurs when the outer cladding and the inner core deform at different rates. It is defined by unequal reduction ratios between the components, which can cause cracking, necking, or defective geometries.
Disproportionation reaction – It is a specific type of redox (oxidation-reduction) reaction. In this process, a single reactant containing an element in an intermediate oxidation state simultaneously undergoes both oxidation (losing electrons, increasing oxidation number) and reduction (gaining electrons, decreasing oxidation number) to form two different products.
Disp statement – It is a command in MATLAB (matrix laboratory) used to display the value of a variable or a message without showing the variable name, providing a neater output presentation. It can also concatenate strings and display multiple values in a single line.
Disregistry – It is the magnitude of the displacement of atoms in a crystal lattice from their ideal or perfect crystal positions. It is used to measure the degree of localized atomic disruption or misfit at crystal defects like dislocations and grain boundaries.
Disruption – It typically refers to an unplanned event, hindrance, or disturbance which alters normal working methods, causing lower productivity, equipment failure, or interrupted system operations.
Disruption crack – It is also called discontinuity crack. It is a planar flaw where the material’s micro-structure is separated, compromising structural integrity. These are stress-concentrating defects, including hot tears, fatigue cracks, or stress corrosion cracks, which can lead to sudden, catastrophic failure if left unmitigated.
Disruptive strength – It refers to the threshold stress needed to cause a material to fracture under hydrostatic tension. It represents a material’s capacity to withstand three principal tensile stresses acting simultaneously without failing.
Dissecting micro-scope – It is also called a stereo or stereoscopic microscope. It is an optical tool used to see large, solid items in three dimensions. It uses two separate lens paths to give each eye a different angle. This creates a 3D view. It has a low zoom power (5x to 40x) and a large gap space to work under the lens.
Dissection – In case of a product, it is the systematic process for taking apart and analyzing the product and all its parts. It is an important tool in engineering design. Product dissection helps in understanding how products work, and can also be a source of inspiration when designing a new product. Mechanical dissection is the process of disassembling, inspecting, and reassembling a mechanical device to discover how it works.
Disseminated – It is fine grained material which is scattered quite evenly throughout the rock.
Disseminated ore – It is the ore carrying small particles of valuable minerals spread more or less uniformly through the host rock.
Dissimilar metals – These are two or more different metals in contact. Due to varying surface conductivity, one or more metals can experience accelerated corrosion. Since zinc is high in the galvanic series, it preferentially corrodes to protect most dissimilar metals.
Dissimilar molecule – It is a chemical structure which has substantial differences in its atomic make-up, shape, or bonding patterns compared to another reference molecule. Dissimilar molecules are entities which show substantial differences in their structural characteristics, which can lead to divergent properties and behaviours. In the context of molecular similarity analysis, these differences are quantified using different distance metrics or dissimilarity measures.
Dissipated strain energy – It is the portion of mechanical work or energy lost as heat, plastic deformation, or material damage during the loading and unloading cycle of a material, rather than being stored elastically. It is typically measured by the area inside a stress-strain hysteresis loop.
Dissipation – It is the loss of energy in a system.
Dissipation factor – It is a measure of how much electrical energy a dielectric or insulating material wastes as heat when exposed to an alternating current. Also called loss tangent, a lower dissipation factor means a better insulator and higher efficiency, while a high value points to insulation damage.
Dissipation factor, electrical – It is the ratio of the power loss in a dielectric material to the total power transmitted through it. Hence, it is the imperfection of the dielectric. It is equal to the tangent of the loss angle.
Dissipation function – It is a mathematical expression which measures the rate at which kinetic or mechanical energy turns into heat inside a physical system. It tracks energy losses caused by friction, fluid viscosity, or other irreversible forces.
Dissipation inequality – It is a mathematical statement from thermo-dynamics and systems theory. It says that the rate of energy supplied to a system is always higher than or equal to the rate at which energy is stored, meaning part of the input power is permanently lost or dissipated.
Dissipation range – It is the smallest scale of motion in fluid turbulence where kinetic energy is converted into heat by viscous forces. At this tiny level, fluid friction stops the transfer of energy and turns the movement into thermal energy.
Dissipation rate – It is the rate at which kinetic energy in a turbulent fluid flow is converted into thermal energy (heat) by viscous forces. Large swirling eddies break down into smaller ones until fluid viscosity destroys the remaining motion.
Dissipation term – It is a mathematical expression in physics and engineering equations which shows how usable energy turns into waste heat or disperses irreversibly. It frequently represents friction, viscous drag, or electrical resistance slowing down a system.
Dissipative component – It is a physical, mechanical, or electrical part which converts usable energy, such as work or electrical current, into irreversible forms like heat or sound, effectively removing that energy from the system.
Dissipative framework – It is a conceptual or mathematical model for open systems which exchange energy, matter, or information with their environment, continuously dissipating energy to maintain a stable, non-equilibrium organized state.
Dissipative process – It is a thermodynamic change where organized or useful energy converts into random, less available forms like heat. This action is irreversible, increases total entropy, and lowers a system’s capacity to perform external work.
Dissipative region – It is also called dissipative zone. It is a specific area in a system, structure, or fluid where energy is actively absorbed, converted, nd lost, typically transformed from kinetic or electrical energy into heat through friction, viscosity, or electrical resistance.
Dissipative structure – It is an open thermo-dynamic system operating far from equilibrium which spontaneously generates and maintains internal order by continuously exchanging energy, matter, and entropy with its external environment.
Dissipative theory – It is also known as dissipative framework. It open systems far from thermodynamic equilibrium which continuously exchange energy, matter, or information with their environment, dissipating energy to maintain stable, ordered structures or input-output stability.
Dissipative zone – It is a specific area or structural region designed to absorb, reduce, or release energy, such as seismic shock, electrical charge, or ocean wave force, to protect the rest of a system from damage.
Dissipator – It is something or someone that scatters, wastes, or removes energy, heat, or resources. The word normally refers to an engineering device which slows down fluid or spreads away heat, but it broadly means anything which causes a loss or dispersion.
Dissociated ammonia – It is a reducing gas produced by the thermal decomposition of anhydrous ammonia over a catalyst, resulting in a gas of 75 % hydrogen and 25 % nitrogen. The dissociation of ammonia is an endothermic reaction (needs heat) defined by the chemical equation ‘2NH3 = N2 + 3H2’.
While the raw formula yields 75 % hydrogen (H2) and 25 % nitrogen (N2) by volume, the cracking efficiency is normally (99 %) or higher. This ensures that almost all of the raw ammonia is broken down, leaving only trace, non-reactive quantities of raw ammonia in the final gas.
Dissociated ammonia hydrogen atmosphere – It is an industrial gas environment composed of (75 %) hydrogen and (25 %) nitrogen. It is generated by thermally ‘cracking’ anhydrous ammonia (NH3) over a heated catalyst (typically nickel). This mixture serves as a highly effective, cost-efficient, and easily stored reducing atmosphere.
Dissociation – It is as applied to heterogeneous equilibria, the transformation of one phase into two or more new phases of different composition.
Dissociation constant – It is a specific type of equilibrium constant which measures how easily a larger complex or molecule separates into smaller components. It shows the strength of binding i.e., a lower value means a tight, strong bond, while a higher value means a weak bond that breaks apart easily.
Dissociation curve – It is frequently represented through an Ellingham diagram. It is a graphical plot of standard Gibbs free energy of formation against temperature. It defines the thermal stability threshold and equilibrium dissociation pressure where a metal compound (like an oxide or sulfide) breaks down into pure metal and gas. It is also is a phase boundary or equilibrium line on a property graph (such as pressure against temperature) which separates stable combined states, like gas hydrates or chemical compounds, from their dissociated free components. Operating on one side of the curve prevents phase change or blockage, while crossing it triggers dissociation.
Dissociation energy – It is the specific quantity of energy needed to break a chemical bond in a molecule through homolytic cleavage, where each resulting fragment retains one of the bonding electrons. It is measured in kilo-joules per mol and serves as a primary measure of chemical bond strength.
Dissociation enthalpy – It is the change in heat energy (dH) needed to break a specific chemical bond or separate a molecular compound into smaller parts (such as atoms or radicals) per mole of substance, normally measured at constant pressure in kilo-joules per mol.
Dissociation pressure – At a designated temperature, it is the pressure at which a phase transforms into two or more new phases of different composition.
Dissociative mechanism – It is a two-step reaction pathway where a molecule or ligand first breaks away from a central atom or surface to form a reactive intermediate before a new species bind. The initial bond-breaking step controls the overall reaction speed.
Dissolution – It is the process of dissolving, splitting, or separating into component parts.
Dissolution etching – it is the development of micro-structure by surface removal.
Dissolution potential – It is frequently tied to electro-chemical or anodic dissolution. It is the specific electrical potential at which a metal or solid material oxidizes and actively dissolves into an electrolyte solution as ions, driven by thermodynamic and electrical forces.
Dissolution process – It is the physical or chemical operation where a solid, liquid, or gas solute mixes into a liquid solvent to create a uniform, homogeneous solution. It involves breaking intermolecular bonds and transferring mass across the phase boundary, driven by system kinetics and thermodynamics.
Dissolution rate – It is the speed at which a solid substance (solute) dissolves into a liquid (solvent) over a specified time interval. It measures mass transfer from a solid surface into a liquid phase per unit of time.
Dissolution reaction – It is the process where a solid, liquid, or gas substance mixes with a liquid solvent to form a uniform fluid solution. This phase change involves breaking internal structural bonds to release atoms, ions, or molecules into the liquid.
Dissolution zone – It is a specific region where solid materials chemically react with fluids and dissolve. This process leads to material loss, higher porosity, and structural changes.
Dissolved air flotation – It is an engineering water clarification process which removes suspended solids, oils, greases, and algae. It works by dissolving air into water under high pressure and releasing it at atmospheric pressure to form micro-bubbles that attach to impurities and float them to the surface for skimming.
Dissolved carbon – It is the carbon which has gone into atomic solution within molten iron or steel. It serves as the fundamental alloying element in cast irons, dictating the metal’s fluidity, melting temperature, and whether it solidifies as strong, ductile iron or brittle, white iron. In aquatic environments, dissolved carbon is operationally defined as the fraction of carbon-containing compounds which can pass through a fine filter (typically 0.22 micro-meters to 0.45 micro-meters). It is divided into two main categories namely dissolved organic carbon (DOC) and dissolved inorganic carbon (DIC).
Dissolved carbon di-oxide – It is the carbon di- oxide (CO2) gas which has been trapped and dissolved within a liquid, normally water. It acts as a main nutrient for aquatic plant life, and plays an important role in environmental climate regulation.
Dissolved gas – It is a gas molecule held completely in solution within a liquid under specific pressure and temperature limits. When system pressure drops or temperature rises past saturation limits governed by Henry’s law, these gases form free bubbles, causing cavitation, two-phase flow, or equipment degradation.
Dissolved gold – It is solid gold transformed into a soluble liquid chemical complex, such as a gold cyanide or chloroaurate ion, using oxidants and complexing agents. This fluid state allows engineers to separate, extract, and purify precious metal from low-grade ores or electronic waste.
Dissolved inorganic carbon – It is the sum of inorganic carbon species in a solution. In aquatic environments, it is defined mathematically as the combined concentrations of dissolved carbon di-oxide (CO2), carbonic acid (H2CO3), bicarbonate (HCO3-), and carbonate [(CO3)2-].
Dissolved organic carbon – It is operationally defined as the fraction of organic matter in water which can pass through a fine filter (typically between 0.22 micro-meters and 0.45 micro-meters in size). It represents the pool of soluble, carbon-based organic compounds derived from decomposed plant and animal matter.
Dissolved oxygen – It is a measurement of the quantity of oxygen available to aquatic organisms. Temperature, salinity, organic matter, bio-chemical oxygen demand, and chemical oxygen demand affect dissolved oxygen solubility in water.
Dissolved oxygen concentration – It refers to the quantity of oxygen which is dissolved in water, which is critical for processes such as bio-degradation in wastewater treatment and hydrological monitoring of aquatic environments.
Dissolved oxygen content – It is the concentration of free, non-compound molecular oxygen (O2) present in water or other liquid systems. It is typically measured in milligrams per litre or parts per million (ppm), and serves as an important parameter for evaluating biological activity, pollution levels, and chemical corrosiveness.
Dissolved oxygen electrode – It is an electro-chemical sensor used to measure the concentration or partial pressure of oxygen dissolved in a liquid medium. It relies on a gas-permeable membrane and an internal electrolyte solution to reduce oxygen and generate an electrical current proportional to the oxygen level.
Dissolved oxygen level – It is the measure of free, non-compound oxygen molecules (O2) present in water or other liquid solutions. It is normally quantified in milligrams per litre, parts per million (ppm), or percent saturation.
Dissolved oxygen tension – It is the partial pressure of oxygen dissolved in a liquid medium. It acts as the driving force which pushes oxygen molecules from a liquid solution into biological cells or micro-organisms.
Dissolved particles – These are individual molecules or ions of a solid, liquid, or gas which have completely integrated into a solvent (typically a liquid like water) to form a homogeneous solution. These particles are smaller than 1 nano-meter in size and cannot be removed by mechanical filtration or sedimentation.
Dissolved salt – It is an ionic compound (solute) broken down into free-floating positive and negative ions within a liquid solvent like water. These particles are smaller than 1 nano-meter, pass through mechanical filters, and directly alter the fluid’s electrical conductivity, osmotic pressure, and corrosiveness.
Dissolved silica – It refers to silicon di-oxide (SiO2) present in a soluble, non-colloidal form within water, mainly as un-ionized silicic acid [H4SiO4 or Si(OH)4], typically ranging from 1 milligram per litre to 30 milligrams per litre in natural systems.
Dissolved solids – It refers to the measure of organic and inorganic substances within a liquid in an ionized, molecular and colloidal or suspended form.
Dissolved solute – It is the minor component in a homogeneous liquid, gas, or solid solution which gets dispersed as atoms, ions, or molecules and completely integrated into the major component (the solvent).
Distance-bath-lance – It is a critical metric in pyro-metallurgy and steelmaking representing the height of an oxygen lance’s nozzle tip above the surface of a molten metal bath. It is important for optimizing oxygen jet penetration, preventing violent splashing, and controlling chemical reactions. In basic oxygen furnaces (BOF) and smelting, distance-bath-lance (DBL) management dynamically regulates the kinetic energy of super-sonic oxygen jets.
Distance beta – It very frequently refers to distance-based beta diversity in ecology and statistics, measuring how community composition or species dissimilarity changes across a physical or environmental distance. It can also denote a point of maximum torsional load in engineering or statistical power trade-offs in testing.
Distance conveying – It refers to the specialized mechanical or pneumatic transport of materials, goods, or bulk substances across substantial spatial gaps or long stretches from a starting point to a destination.
Distance, downstream – Downstream distance is the spatial measurement from a starting point along the direction of a fluid’s current, network flow, or process path. In physical waterways, it is the length measured from a reference point moving toward the river mouth. It is the measurement taken from a specific point downstream of a wind turbine, typically expressed in terms of multiples of rotor diameters, such as five rotor diameters in certain analyses.
Distance estimate – It is an educated guess or approximate calculation of the space between two or more physical points, objects, or sound sources when exact measurement is not available.
Distance estimation – It is a quantitative process used to approximate the spatial separation or gap between two or more objects, points, or sound sources. It relies on sensors, geometry, or statistical formulas when exact physical measurement is impossible or impractical.
Distance, fibre – Fibre distance refers to the nearest neighbour distance (NND) between fibres, which characterizes the short-range interaction and degree of clustering of fibres within a reference volume element (RVE). This distance influences considerably stress concentrations at the fibre-matrix interface, affecting the local and overall failure mechanisms of composite materials.
Distance from neutral axis – The neutral axis is an imaginary line within a beam or object where there is no bending stress (zero stress) and no change in length (zero strain) during bending. It separates the region being compressed from the region being stretched. The stress (S) at any given point is directly proportional to its perpendicular distance (y) from this axis. The distance from the neutral axis determines the normal stress (S) using the formula ‘S = My/I’, where ‘M’ is the bending moment and ‘I’ is the area moment of inertia. It is also highly relevant in plate rolling and bending, where this axis shifts slightly toward the inside of the bend.
Distance function – It is a mathematical rule which measures how far apart two points or objects are, returning a zero value if they are identical and a positive number if they are different.
Distance limitation – It is the maximum physical or geographical range which a signal, vehicle, or process can travel or operate effectively before experiencing failure, degradation, or a set boundary.
Distance metric learning – It is a machine learning technique which automatically constructs a task-specific distance function from data. Instead of using fixed, generic measures like Euclidean distance, it learns a custom metric to make similar data points close together and dissimilar points far apart.
Distance product – It very frequently refers to the inner product distance used in vector spaces and vector search databases, where the similarity or distance between two vectors is calculated by multiplying their corresponding components and summing the results.
Distance propagation – It normally refers to propagation distance, the spatial range or path length over which a signal, wave, or particle travels effectively through a medium before it attenuates or loses integrity. In specialized contexts like radio physics, it can also mean skip distance, the minimum gap where a refracted sky wave returns to earth.
Distance sensor – It is an electronic device which measures the physical space or gap between itself and a target object without making physical contact. It emits a wave or beam of energy, such as sound or light, and calculates how long it takes to bounce back.
Distance transmission – It very frequently refers to long-distance transmission, which is the process of sending electrical power, data, or signals across substantial geographical spans. It needs specialized media and equipment to maintain signal strength and prevent severe energy loss.
Distance vector – It is a routing algorithm used to determine the best path for forwarding data packets between nodes. It is based on the concept of distance vectors which are used to estimate the distance or cost of reaching a destination network.
Distance vector protocol – It is a type of routing protocol which is the oldest and most basic in practice in computer science. It involves nodes exchanging information about the cost or distance to different destinations in order to determine the shortest paths. The protocol updates the cost to a destination when it receives new information from a neighbour node.
Distance vector routing – It is a network algorithm where routers find the best path for data by sharing their routing tables with direct neighbours. Each router uses the Bellman-Ford equation to calculate total distance and updates its path choices over time.
Distension – It is also called distention. It means the act of swelling, stretching, or expanding outward because of pressure from inside.
Distillation – It is the process of separating the component substances of a liquid mixture by exploiting differences in the relative volatility of the mixture’s components through selective boiling and subsequent condensation. The apparatus used to distill a substance is called a still, and the re-condensed substance yielded by the process is called the distillate.
Distillation column – It is a critical piece of equipment which is used mainly in the chemical processing to separate mixtures into their parts or fractions. It is used in the distillation of liquid mixtures to separate the mixture into its component parts, or fractions, based on their differences in volatility.
Distillation temperature – It is the specific temperature measured during a thermal separation process when a liquid mixture vapourizes or when a set percentage (like 10 % or 90 %) of a fuel sample is recovered as a distillate, used to evaluate component volatility and boiling points.
Distilled water – It is that water which is produced by distillation process that is first evaporating the treated water and then condensing the water vapours. Distilled water is the purest form of water and normally used in laboratories for the wet chemical analysis of the materials.
Distinct element method – It is a numerical modelling technique used to simulate the bulk behaviour of granular, discontinuous materials (like powders, ores, and aggregates) by tracking the motion and interaction of individual particles over time. Unlike continuum methods (like the finite element method) which treat materials as a single solid mass, distinct element method (DEM) treats materials as a collection of independent, discrete particles.
Distorted image – It is an optical or digital alteration where straight lines bend, or object shapes warp, causing a shift from the true geometric proportions of a scene. It changes spatial positions without losing core focus or sharpness.
Distorted pattern – It refers to a casting pattern which has been intentionally warped or modified out of its true geometric shape. This modification is used to counteract the natural warping and uneven shrinkage which occurs as molten metal cools and solidifies inside the mould.
Distorted twin-band boundaries -These boundaries refer to highly strained, irregular interfaces separating a twinned crystal region from its parent matrix. Unlike pristine coherent twin boundaries with perfect mirror symmetry, distorted boundaries feature atomic-level misalignments, sessile dislocations, and high internal stresses.
Distorted video – It is a video signal or digital file altered from its original form, resulting in unwanted visual artifacts, geometric warping, or waveform degradation during capture, compression, or transmission.
Distortion – It is a deviation from an original size, shape, or contour which occurs because of the application of stress or the release of residual stress. Some steel sections distort during galvanizing due to differential heating and cooling or inbuilt welding stresses. Distortion occurs when the application of heat during the galvanizing process releases stress from the steel induced in the fabrication process or during the steel making process. Distortion is of concern when galvanizing asymmetric structural shapes and / or fabrications.
Distortional buckling – It is a structural instability mode in thin-walled, open-profile members (like cold-formed steel channels or Z-sections) where the cross-section changes shape. It involves both the rotation of the flange at the web-flange junction and the displacement of edge stiffeners, occurring at a half-wavelength between local and global buckling.
Distortional mode – It is normally seen in distortional buckling. It is a type of structural failure or deformation where a member undergoes a change in its cross-sectional shape through the rotation or displacement of its flanges and stiffeners, occurring at an intermediate half-wavelength between local buckling and global (flexural-torsional) buckling.
Distortion behaviour – It is the unwanted change in the original shape, size, or signal wave-form of a material, structure, or system when it experiences external forces, heat, or internal stresses.
Distortion control – It is the application of engineering techniques, such as pre-heating, fixturing, and strategic weld sequencing, to minimize dimensional changes caused by thermal expansion and contraction during welding. It is the use of specific methods, tools, and plans to stop or reduce unwanted shape changes and warping in materials. These size errors happen during manufacturing, heat treatment, or welding because of uneven heating, cooling, and internal stress. Proper distortion control is important to ensure that heat exchanger tubes and shells align perfectly for assembly and operation.
Distortion energy – It is the portion of internal strain energy stored in a stressed material which changes its shape (causes angular or shear distortion) rather than its volume. It serves as the physical basis for the distortion energy theory (also known as the von Mises yield criterion) used in mechanical engineering.
Distortion energy theory – It is also called the Von Mises yield criterion or maximum octahedral shear stress theory. It states that a ductile material begins to yield when the distortion strain energy per unit volume under complex loading equals the distortion energy at the yield point in a simple tension test.
Distortion engineering – It is a systematic approach which treats dimensional and shape changes in a work-piece as the cumulative result of an entire production chain, from casting and machining to heat treatment, rather than the fault of a single processing step.
Distortion function – It is a mathematical mapping which measures the difference or error between an original value, signal, or probability distribution and its reconstructed or modified version.
Distortion, harmonic – Harmonic distortion is the change in a wave’s shape. It happens when extra frequencies appear in a system. These new frequencies are whole-number multiples of the original main frequency. Non-linear parts in audio or power equipment cause this problem.
Distortion limit – It is the maximum allowable threshold of signal or structural deformation. In electrical engineering, it restricts harmonic waves and total harmonic distortion (THD). In telecommunications, it marks the point where wave-form shape errors override signal power. In mechanics, it limits shape change energy before material yielding.
Distortion measure – It is a non-negative cost function ‘d(u, v)’ which quantifies the numerical difference, error, or loss incurred when an original source symbol or signal ‘u’ is reproduced or compressed as ‘v’. A value of zero means there is no error.
Distortion measurement – It is the process of quantifying how much a system, device, or signal alters an original waveform or shape. It evaluates signal purity and linearity in electronics, structural deviations in mechanics, or error rates in data compression.
Distortion model – It is a mathematical or physical representation used to predict, measure, or correct how a system (such as a camera lens, audio amplifier, or hydraulic scale layout) alters a signal, image, or object from its true, original form.
Distortion performance – It evaluates how much an electronic, acoustic, or data system alters a signal’s original shape, waveform, or structure. It measures fidelity, showing how clean a system stays or how much unwanted noise, clipping, or error it adds during processing.
Distortion power – It is an electrical power component in non-linear circuits which occurs when voltage or current wave-forms are non-sinusoidal. It represents energy which oscillates between the source and a non-linear load because of the harmonic frequencies, performing no useful work.
Distortion residual – It is the leftover error or discrepancy which remains after a mathematical model, calibration algorithm, or correction process attempts to remove structural, optical, or electronic distortion. It represents the uncorrected difference between an ideal value and the actual measured value.
Distortion spectrum – It is the frequency-domain representation of unwanted harmonic and non-harmonic components added to a signal by a non-linear or imperfect system. It displays the relative amplitudes of individual extra frequencies, such as multiples of a fundamental frequency, generated when a wave-form is altered during processing or transmission.
Distortion, waveform – Waveform distortion is the deviation from an ideal sine wave of power frequency, characterized by the spectral content of this deviation.
Distracted driving – It refers to any activity which diverts attention from driving, including cell phone use, texting, eating, talking to passengers, and adjusting vehicle controls.
Distress signal – It is an internationally recognized call or sign used by people facing severe, life-threatening danger to ask for immediate help. It can also mean a non-verbal cue showing that a person needs rescue or relief.
Distribond – It is a specialized, proprietary blend of siliceous clay and bentonite which is used as a binding agent for moulding sands. It provides the necessary adhesion and plasticity to shape the mould and is also used to distribute and control sand grain sizes.
Distributed approach – It is a method where multiple independent computers or nodes work together over a network to share tasks, data, and power instead of relying on one single central server. This se-tup makes systems faster, larger, and safer if one-part breaks.
Distributed coding – It refers to a technique where each video frame is compressed separately, resembling a decentralized approach. This method shifts complexity from the encoder to the decoder and is widely used in video compression algorithms.
Distributed compression – It is the process of reducing data size across multiple separate physical sources or network nodes before sending it to a central receiver. It compresses correlated information without needing the individual sources to communicate with each other first.
Distributed computing – It is a model where multiple independent computers, called nodes, work together over a network to solve a big problem. Instead of using one fast computer, it splits a task into small parts. Each part runs at the same time on a different machine, and the results are joined together.
Distributed control law – It is a mathematical rule or strategy where individual agents or local controllers make decisions using only local information and neighbour interactions, achieving global coordination without a central master unit. It is widely used in multi-agent networks, robotics, and distributed control systems (DCS).
Distributed control system – It is a computerized control system for a process or plant normally with several control loops, in which autonomous controllers are distributed throughout the system, but there is no central operator supervisory control. Distributed control system automates industrial equipment used in continuous and batch processes, while reducing the risk to people and the environment.
Distributed coordination function – It is the core baseline medium access control (MAC) protocol for Institute of Electrical and Electronics Engineers standard IEEE 802.11 wireless local area networks (Wi-Fi). It uses a decentralized carrier sense multiple access with collision avoidance (CSMA/CA) scheme to let multiple devices share the air fairly without a central controller.
Distributed electricity – It is normally known as distributed generation or distributed energy. It is the local production of power. Small systems make electricity right at or near the place where people use it. This approach stands in contrast to old, large power plants which send electricity over long wires.
Distributed energy – It means making and storing power right at or near where people use it. Instead of using huge power plants far away, it uses small local systems like roof-top solar panels, home batteries, or electric cars.
Distributed energy resources – These are small-scale, decentralized power generation and storage systems situated near the point of use. Unlike traditional centralized power plants, distributed energy resources (DERs) produce and manage electricity locally, frequently ‘behind the meter’ on the consumer’s property.
Distributed energy storage – It is a system of small-scale energy storage devices, mainly batteries, located at or near the point of use, rather than at large, centralized power plants. It stores excess power (like solar energy) for use during high-demand times, improving grid stability and reliability.
Distributed energy system – It generates, stores, and manages power close to where people use it. It uses small units instead of one big, far-away power plant. These systems can work on their own or connect to the main power grid.
Distributed force – It is a load spread out over a line, a surface area, or an entire volume rather than acting at a single geometric point. Common examples include wind pressure on a wall, water pushing against a dam, or gravity acting on the total mass of an object.
Distributed gauge volume percent – It is an empirical parameter used in metallurgy and materials science to quantify a material’s propensity for localized plastic flow (shear banding) during deformation processes like forging. A higher distributed gauge volume (DGV) percent indicates better workability, as the material uniformly distributes strain. The parameter is calculated using cylindrical, uniaxially compressed test samples with a reduced gauge section.
Distributed generation – It is the practice of producing electricity using small-scale power systems located at or near the point of use, rather than relying on massive, centralized power plants and long transmission lines.
Distributed generators – These are decentralized, small-scale electricity generation units, ranging from a few kilowatts to 100 megawatts, situated at or near the point of use. Unlike traditional centralized power plants, distributed generators (DGs) reduce reliance on long-distance transmission lines. They are normally powered by solar panels, small wind turbines, fuel cells, or combined heat and power (CHP) systems.
Distributed generation unit – It is a small-scale power generation system installed at or near the point of use. Ranging from a few watts up to 10 megawatts, these decentralized units produce electricity locally rather than relying on massive, centralized power plants.
Distributed impact test – In impingement erosion testing, it is an apparatus or method which produces a spatial distribution of impacts by liquid or solid bodies over an exposed surface of a sample. Examples of such tests are those employing liquid sprays or simulated rain-fields. If the impacts are distributed uniformly over the surface, the term uniformly distributed impact test can be used.
Distributed measurement system – It is a network of independent smart devices and sensor nodes placed at different physical locations to collect, process, and share data. These nodes link through a communication network to a central unit instead of routing every long sensor cable to one main machine.
Distributed model predictive control – It is an advanced control strategy for large-scale or inter-connected systems. Instead of using a single central computer to manage everything, distributed model predictive control (DMPC) splits the overall task among multiple smaller, local controllers. Each local controller handles a specific part of the system, talks to neighbouring controllers, and makes predictions to optimize performance while respecting operational limits.
Distributed moment – It is the portion of an unbalanced bending moment at a joint that gets allocated or split into the connected adjacent spans of a beam or frame. This allocation is based on the relative stiffness of each member during the iterative balancing process of the moment distribution method. In statistics or probability, a ‘moment of a distribution’ describes the shape and location of a set of data or a probability function using power-weighted averages (such as the mean or variance).
Distributed network – It is an architecture where multiple autonomous nodes or computers collaborate over a communication medium to achieve a common goal. There is no central controller. Tasks are divided and processed in parallel, which maximizes efficiency and eliminates single points of failure.
Distributed noise – It refers to random unwanted signals or disturbances that are spread across a physical medium, a spatial area, or a mathematical domain (such as time, space, or frequency). Rather than coming from a single localized point, the noise originates from continuous or multiple independent sources.
Distributed numerical control – It combines the centralized data base feature of direct numerical control with the distributed computer power available in computer numerical control machine tools. This creates a communications network for the shop floor which eliminates paper tape and provides an automated part programme library, status reporting on machine tool operation, and the capability to run part programmes of practically infinite length.
Distributed parameter system – It is a dynamical system whose state variables depend on both time and continuous spatial positions. These systems have infinite-dimensional state spaces and are governed by partial differential equations (PDEs) rather than ordinary differential equations.
Distributed population – It refers to a population which is spatially organized into sub-populations, frequently existing in discrete clusters or varying densities, which can influence individual behaviours and population dynamics. This spatial variation is important as it affects the perceived density and resulting consequences for both individuals and the population as a whole.
Distributed power generation – It is a system where electricity is produced by small, local units right at or near where people use it. This setup stands apart from old, massive power plants that send electricity over long wires.
Distributed power source – It is a small-scale, decentralized electricity generator or storage unit located at or near the point of use. Instead of relying on distant mega-power plants, it generates power locally on the customer’s side of the power grid.
Distributed programming – It is the practice of developing software applications which run on multiple independent computers and communicate by passing messages.
Distributed Raman amplification – It is an optical amplification technique where the actual transmission fibre itself acts as the gain medium. High-power pump lasers inject light into the fibre to amplify data signals through stimulated Raman scattering, improving signal strength and noise performance continuously over long distances.
Distributed random vector – It is a list of multiple random variables grouped into a single vector. Its behaviour is defined by a joint probability distribution which shows how all the parts work together.
Distributed reaction zone – It is a combustion regime in fluid dynamics where turbulence is so intense that it breaks down the traditional thin flame sheet. Turbulent mixing outpaces chemical reaction rates, spreading thermal energy and reactive radicals over a thick, wide volume rather than a distinct boundary.
Distributed renewable generation – It is the small-scale production of electricity from clean sources like solar or wind directly at or near the place where people use it. Instead of sending power over long power lines from huge, distant power plants, this local setup feeds energy straight into the local grid or a home.
Distributed sensor – It is a system or continuous medium where measurements are taken across an extended spatial area. It either uses a network of separate nodes which share data or a single continuous medium, like a fibre-optic cable, where every point acts as a measuring device.
Distributed smart camera – It refers to a network of cameras which operate noncentrally, allowing for improved detection results through co-training and collaboration among multiple camera views. This architecture improves efficiency in detecting objects, such as pedestrians, by leveraging information from various camera angles without the need for centralized processing.
Distributed smart camera system – It is a network of independent vision sensors. Each camera has its own built-in processor to run computer vision tasks locally. The cameras talk to each other to share data instead of sending all raw video to a main server.
Distributed solution – It is a system or software approach where processing tasks, data, and decision-making are spread across multiple independent computers or nodes connected through a network. These separate machines communicate and work together to act as a single, unified system.
Distributed source coding – It is a method of compressing multiple correlated data sources separately without letting the encoders communicate with each other, while still achieving the same compression efficiency as joint encoding by using a single central decoder.
Distributed transfer function method – It is a closed-form analytical technique used to model, analyze, and control complex distributed parameter systems governed by partial differential equations. It replaces traditional finite element shape functions with exact analytical transfer functions along structural domains, providing high accuracy with fewer computational nodes.
Distributed transmission method – It refers to a communication or power strategy where signals, data, or electrical properties are spread across multiple synchronized nodes, lines, or continuous circuit elements instead of relying on a single centralized source or lumped component.
Distributing electricity – It is the final stage in delivering electrical power. It moves energy from local substations through medium- and low-voltage lines directly to homes, offices, and factories. This process sits between high-voltage transmission and the end user.
Distribution – It broadly refers to how physical quantities, loads, or data spread across a system. It is defined in three main ways namely probability (data / variables), physical networks (energy / fluids), and mathematical analysis (generalized functions). It is also is the process of making a product or service available for the customer or the organizational user who needs it. It is also the set of frequencies or probabilities assigned to different outcomes of a particular event or trial.
Distributionally robust optimization – It is a method for making choices when the exact odds of future events are unknown. Instead of picking one guess or one set of odds, distributionally robust optimization (DRO) looks at a group of possible odds. It finds the choice that works best even if the worst-case odds turn out to be true.
Distribution and partitioning behaviour – This behaviour describes how a substance, molecule, or dataset spreads and divides itself among different phases, compartments, or structural nodes within a physical, chemical, or computational system. It dictates the equilibrium concentrations or spatial locations of components based on their intrinsic affinities and environmental conditions.
Distribution automation – It is an integrated system of smart sensors, communication networks, and computer-controlled switches which allows electric power organizations to monitor, coordinate, and operate medium-voltage distribution grids in real time from a remote location.
Distribution behaviour – It refers to how the values of a variable or the components of a system spread, scatter, or allocate themselves across a specific range, space, or set of conditions. It describes the frequency, pattern, or probability of outcomes.
Distribution board – It is a piece of electrical switchgear which distributes electric power to multiple branch circuits.
Distribution channel – It is the physical or virtual pathway, such as supply routes, transmission lines, or data paths, followed by a product, fluid, power signal, or data stream as it moves from its source to the end user.
Distribution coefficient – It is defined as the concentration of solute in the organic solvent divided by the concentration of solute in the aqueous phase.
Distribution control – It is very frequently implemented as a distributed control system (DCS). It is an automated architecture where control functions are spread across several local, autonomous controllers rather than managed by one single central computer. These systems safely regulate continuous industrial processes like chemical manufacturing, power generation, and water treatment.
Distribution cooperative – It typically refers to a member-owned utility entity that delivers electricity or resources to end-users, or a decentralized framework where independent nodes or multi-agent systems share assets and coordinate control without a centralized authority.
Distribution density – It normally means a probability density function (PDF). It is a mathematical rule. It shows how likely a continuous random value, like wind load, material strength, or part size, is to show up in a certain range.
Distribution factor – It is also known as the breadth factor or belt factor. It is the ratio of the actual electro-motive force (EMF) induced in a distributed winding to the electro-motive force which is induced if all the coils were concentrated in a single slot. Since it accounts for the phase differences between voltages induced in different slots, its value is always less than 1.
Distribution function – It is the function, denoted F(x), which gives the cumulative frequency or probability which random variable ‘X’ takes on a value less than or equal to ‘x’.
Distribution management system – It is a collection of software applications used to monitor, control, and optimize electric power distribution grids in real time. It helps grid operators manage power flows, prevent overloads, and restore outages safely.
Distribution model – It is a mathematical or digital representation used to simulate how physical assets, power, data, or statistical variations spread across a system. Depending on the specific engineering branch, it defines network connectivity, load flow, or data routing rules.
Distribution network – It is a system which moves goods from a manufacturer to a customer. It is an interconnected group of storage facilities and transportation routes designed to efficiently deliver products. In case of electric power, distribution network is a system which delivers electricity from power sources, like power plants, to consumers, including residential, commercial, and industrial areas. It is the final stage in the electric power system, responsible for providing power at the required voltage, current, and frequency to meet user demand.
Distribution network operator – It is a regulated entity responsible for managing, operating, and maintaining the local electricity distribution infra-structure. Distribution network operators (DNOs) deliver power from the high-voltage transmission grid to end consumers.
Distribution of a variable – It is also called probability distribution of a variable. It is the collection of all values of a variable along with their associated probabilities of being observed.
Distribution of data – It is a measure to determine the quality characteristics. When the distribution of data is symmetric then there are same numbers of observations below and above the mean. This is what is normally found when only normal variation is present in the data. When a disproportionate number of observations are either above or below the mean, then the data has a skewed distribution.
Distribution of relaxation times – It is a mathematical data analysis method. It converts frequency-dependent measurement data, like electro-chemical impedance spectroscopy (EIS), into a spectrum of time constants. It helps split overlapping physical or chemical processes without guessing an equivalent circuit model first.
Distribution of sources – It refers to the spatial arrangement of line sources characterized by a source strength density function, f(x), which influences the pressure field and is mathematically represented by an integral expression relating to the coordinates of the sources.
Distribution parameter – It is a constant value which indexes a probability model, defining the specific centre, spread, or skew of a random variable’s behaviour. These parameters, such as the mean, variance, or shape factor, allow teams to model material fatigue, system reliability, and environmental loads.
Distribution ratio – It is the ratio of the total analytical concentration of a solute in the extract (regardless of its chemical form) to its total analytical concentration in the other phase.
Distribution, sand grain – Sand grain distribution refers to how these particle sizes are spread across different sieve sizes, dictating the mould’s strength, gas permeability, and the resulting surface finish of the metal.
Distribution substation – It is a facility within an electrical power system which steps down the voltage from sub-transmission levels to the primary distribution level, ready for delivery to consumers. It essentially acts as a link between the transmission system and the final distribution network, ensuring the correct voltage is delivered to homes, commercial installations, and industries.
Distribution system – It is the final stage of the power grid. It bridges the gap between high-voltage transmission lines and the end-user, safely stepping down bulk electricity at substations to supply the consumers with safe, usable voltage. Distribution system originates at a distribution substation and includes the lines, poles, transformers and other equipment needed to deliver electric power to the consumer at the needed voltages.
Distribution system efficiency – It measures how well an electrical network delivers power from a substation to end-users while minimizing energy losses. It is the ratio of useful power output delivered to consumers compared to the total power input injected into the distribution grid.
Distribution system operator – It is an entity responsible for operating, managing, and maintaining local electricity distribution networks. They take electricity from high-voltage transmission grids and safely route it at lower voltages to end-users like homes and businesses. As the energy landscape evolves, the role of the distribution system operator (DSO) has expanded considerably. Here are the core distinctions between traditional grid management and modern DSO (distribution system operator) operations.
Distribution system modelling – It is the process of creating mathematical and computer representations of electrical power or fluid networks. These models simulate how energy or resources flow from a source to end users. They help engineers design, test, and manage safe, efficient, and reliable systems.
Distribution system operator – It is an entity that operates, maintains, and develops local or regional electric power distribution networks. Distribution system operators (DSOs) deliver electricity from high-voltage transmission grids or local generation units to end-users like homes and organizations, actively managing active power flows, grid stability, and smart-grid integrations.
Distribution transformer – It is a power transformer, normally used to change the utility distribution voltage to a lower voltage for use on the user premises.
Distribution trays – These are frequently called liquid distributors. These are internal devices used in industrial columns (like distillation, absorption, or chemical reactors) to evenly spread descending liquid across the cross-section of the vessel. Their main function is to maximize mass and heat transfer by ensuring uniform contact between liquid and vapour.
Distribution utility – It is an enterprise or system operator which maintains the local physical infrastructure, such as wires, transformers, and substations, to deliver electricity or other necessary services from high-voltage transmission grids directly to end-use retail consumers.
Distribution voltage level – It is the range of medium and low voltages for main lines and under 1 kilo-volt for secondary / utilization lines) used to deliver electrical energy from local substations directly to commercial, industrial, and residential end users.
Distributor – Distributor is an intermediary entity who purchases products in bulk from a manufacturer and resells them to retailers, other wholesalers, or end-consumers. They act as a critical bridge to ensure products reach their intended market efficiently.
Distributor sections – These sections refer to the internal components of heat exchangers which guide fluid streams to and from nozzle openings, ensuring uniform flow distribution across the exchanger block. They are designed to equalize pressure and accommodate different flow configurations, such as counterflow and crossflow.
Distruptive strength – It is also called disruptive strength. It is the maximum strength of a metal when subjected to three principal tensile stresses at right angles to one another and of equal magnitude.
Disturbance – It is any unwanted, external or internal change or deviation in a system which negatively affects its performance or output. These unplanned disruptions force systems to adjust to maintain stability and achieve their target goals.
Disturbance accommodating control – It is an advanced control systems engineering strategy which actively estimates and cancels out unknown external disturbances and system uncertainties in real time. Instead of just reacting to errors after they happen, disturbance accommodating control (DAC) models the specific wave-form pattern of a disturbance and adds a corrective signal to the control input.
Disturbance accommodation – In control systems engineering, it is a strategy which detects, estimates, and counteracts external forces or internal model errors in real-time. It uses an observer (like a Kalman filter) to measure unknown disturbances and adds a correction signal to the control input to keep the system stable.
Disturbance accommodation control – It refers to a control strategy designed to achieve speed regulation and alleviate blade loads in wind turbines while compensating for wind disturbances. It combines the full-state feedback law with a disturbance feedback law to improve system response to varying wind speeds and other disturbances.
Disturbance decoupling – It is a design method which makes a system’s output completely safe from external noise or unknown outside changes. A controller is built so that unwanted outside signals have a zero effect on the final measured output.
Disturbance factor – It is a numerical coefficient used in geo-technical and rock mechanics to quantify the degree of physical damage, fracturing, and stress relaxation induced in a rock mass because of the excavation processes like blasting or heavy mechanical ripping.
Disturbance model – It is a mathematical representation of unmeasured external inputs, environmental shifts, or internal parameter errors which cause a system’s output to deviate from its intended behaviour. It allows control algorithms to predict, estimate, and counter-act these unwanted forces.
Disturbance response – It measures how much an external, unwanted force or input perturbs a system’s state or output. Control systems are explicitly designed to minimize this response, keeping the system stable and accurate despite outside changes.
Disturbance torque – It is an unwanted twisting force that acts on a rotating system. It disrupts the normal movement or position of a machine, or robot joint. Engineers are to measure and control these forces to keep systems stable and accurate.
Disturbance velocity – It is frequently called perturbation velocity. It is the small, fluctuating change in local fluid velocity compared to the steady or undisturbed baseline flow. It measures how much a specific point in a system deviates from average flow conditions during acoustic, vortical, or turbulent oscillations.
Disturbance velocity component – It is also called perturbation velocity component. It is the small, fluctuating, or transient change in flow velocity (u’, v’, w’) relative to a steady base flow or undisturbed uniform stream velocity (Uinfinity).
Disturbed metal – It is frequently called the Beilby layer. It is a thin, amorphous, or highly deformed layer of cold-worked metal which forms on the surface of a work-piece during mechanical grinding, cutting, or polishing. It also refers to the thin layer of altered, cold-worked material formed on the surface of a cast part during post-casting finishing processes like grinding, machining, or polishing.
Disturbing noise – It is an unwanted sound which exceeds background ambient levels by a specific decibel threshold or causes measurable annoyance, sleep disruption, and physiological stress in humans.
Di-tetragonal – It refers to a specific type of crystal symmetry within the tetragonal crystal system (a system where three axes intersect at right angles, with two horizontal axes of equal length and one vertical axis of different length).
Di-tetragonal prism – It is an 8-sided crystal form within the tetragonal crystal system. It features eight vertical faces which intersect the two equal horizontal crystallographic axes at different distances and remain parallel to the vertical axis.
Di-tetragonal pyramid – It is a 16-sided geometric crystal form belonging to the tetragonal crystal system. It consists of two eight-sided pyramids (one facing up, one facing down) which do not share a common base, resulting in 16 trapezoidal or triangular faces.
Dither frequency – It refers to the frequency of a triangular-wave signal added to the pulse demand in a control system, which, when sufficiently high, can mitigate the effects of the minimum pulse-width resolution on system performance.
Dither signal – It is an intentional, low-level noise or periodic oscillation added to a system before quantization or processing. It randomizes quantization errors, prevents harmonic distortion, and helps mechanical or digital components overcome static friction and dead zones.
Di-thio-phosphates – These chemical compounds are normally used as flotation collectors in mineral processing, particularly for sulphides, precious metals, and platinum group minerals. Di-thio-phosphate is an organo-phosphorus chemical compound featuring a phosphorus atom double-bonded to sulphur and single-bonded to two sulphur-hydrocarbon groups. Di-thio-phosphate molecules are important as anti-wear additives in motor oils. These compounds are more soluble in water than xanthates and do not decompose in acidic solutions.
Dittus-Boelter equation – It is a famous empirical correlation in heat transfer. It calculates the convective heat transfer coefficient for fully developed turbulent flow inside smooth circular pipes.
Diutan gum – It is a natural, high-molecular-weight anionic bio-polymer produced by aerobic fermentation of Sphingomonas bacteria. It acts as an advanced rheology modifier which provides exceptional viscosity, thermal stability, and pseudo-plastic (shear-thinning) flow under extreme environmental conditions.
Divalent ion – It is an atom or molecule with an electrical charge or valency of two. These ions are typically cations with a +2 charge (such as Ca2+, Mg2+, or Fe2+) which heavily influence water hardness, scale formation, and chemical reactions in industrial processes.
Divariant equilibrium – When both the pressure and temperature in a unary system are freely and arbitrarily selected, the situation corresponds to having two degrees of freedom, and the phase rule says that only one phase can exist in stable equilibrium. This situation is known as divariant equilibrium.
Divergence angle – It is the angular measure at which a beam of light, laser, or other electro-magnetic radiation spreads out as it moves away from its source or optical aperture. It is typically expressed in units of milli-radians or degrees.
Divergence rate – It is a scalar measure quantifying how intensely a vector field spreads out (positive divergence) or concentrates inward (negative divergence) from an infinitesimal point per unit volume over time. It acts as a spatial time-rate indicator for continuous media like fluid flows or electro-magnetic fluxes.
Divergence speed – It is the critical speed at which the total stiffness about the twist axis becomes zero, leading to an indefinite growth in angular displacement and potential structural failure. It is determined when the aero-dynamic stiffness counteracts the structural stiffness, resulting in a loss of stability.
Divergent passage – It refers to the section of a convergent-divergent nozzle where the cross-sectional area increases, allowing the flow to expand and potentially reach super-sonic speeds as it adjusts to changes in back pressure.
Divergent thinking – It is a thought process in which the mind moves in several different directions, combining different bits of information into new patterns until several different solution concepts evolve.
Diverging nozzle – It is frequently part of a converging-diverging (CD) nozzle. It is a tube with a cross-sectional area which continuously increases from the inlet to the exit. It is used to expand a high-pressure, compressible gas and convert thermal and pressure energy into high-speed, super-sonic kinetic energy.
Diverging section – It is an expanding channel or flow path where the cross-sectional area increases along the direction of flow, causing fluid velocity to decrease and static pressure to recover or supersonic acceleration to occur.
Diversity – It consists of two separate and independent systems which perform the same task so as to reduce the chances of both failing at the same time.
Diversity gain – It is the increase in signal quality or the reduction in required transmission power achieved by sending a signal over multiple independent channels (using space, time, or frequency) to fight signal fading. It changes the error rate graph slope to make wireless or satellite links much more reliable.
Diversity order – It is the number of independent fading channels or branches available in a diversity-combining system. It measures how fast the bit error rate drops as signal power increases. Higher values mean better reliability against signal fading.
Diversity receiver – It is a specialized radio or wireless system which uses two or more independent signal paths or antennas to fix signal drops and noise. It compares or combines these paths so the system gets a clear signal even if one path fails or fades.
Diversity scheme – It is a signal propagation method that uses two or more communication channels with different characteristics to improve the reliability of a message signal. It combats signal fading and interference by combining independent copies of a signal at the receiver end.
Diversity system – It multiple independent paths, sources, or frequencies to make signal reception reliable and prevent total failure when conditions change. It ensures that if one channel or component fades or fails, another takes over.
Diverter – It is a mechanism redirecting materials from one conveyor path to another, necessitating regular checks for proper functioning and alignment.
Diverter gate It is a gate or flap controlling the flow of materials on the conveyor, demanding inspections for smooth operation and effective material diversion.
Diverter system – It is a safety or operational assembly used to redirect the flow of fluids, gases, or bulk materials away from a primary path, area, or equipment to a safe discharge location. Its main job is not to stop or shut off pressure completely, but to safely route the contents elsewhere.
Diverting conveyor – It is a conveyor system used to move products to different areas for sorting or processing, requiring specialized maintenance.
Diverting valve – It is a mechanical flow-control device with one inlet and two or more outlets (or vice versa) used to switch, split, or redirect the pathway of fluids, gases, or bulk solid materials from a single source to different destinations.
Divided cell – It is a cell containing a diaphragm or other means for physically separating the anolyte from the catholyte.
Divider ratio – It is the scaling fraction or proportion by which a voltage divider or current divider splits an input signal into a smaller output value. For a two-resistor voltage divider, it is the ratio of the target resistance to the total series resistance.
Dividing streamline – It is a specific boundary line in a fluid flow field. It separates fluid parcels or paths which have different origins, destinations, or flow behaviours around an obstacle. [1, 2
Division duplex – It refers to methods which allow two-way communication (sending and receiving data) between devices. The two main types are namely frequency division duplex (FDD) which uses two different radio frequencies for simultaneous sending and receiving., and time division duplex (TDD) which uses a single frequency, but splits the communication into different time slots.
Division multiplexing – It is an engineering technique which combines multiple data streams or signals into one single physical channel. It works by dividing the shared transmission medium into distinct, non-overlapping segments, based on frequency, time, wave-length, or code, so that signals travel simultaneously without interfering with each other.
Divorced eutectic – It is a metallographic appearance in which the two constituents of a eutectic structure appear as massive phases rather than the finely divided mixture characteristic of normal eutectics. Frequently, one of the constituents of the eutectics is continuous and indistinguishable from an accompanying pro-eutectic constituent.
Divorced pearlite – It is also known as granular pearlite or spheroidite. It is a modified micro-structure in steel and cast iron where cementite and ferrite grow from austenite in a non-cooperative manner. Instead of the traditional hard, layered (lamellar) structure, it consists of coarse and spherical cementite particles dispersed within a soft ferrite matrix.
DLVO theory – It explains colloidal stability by balancing attractive van der Waals forces and repulsive electro-static forces. When particles approach, their overlapping electrical double layers create an energy barrier. If the barrier is high, particles stay dispersed and if low or overcome by salt, they clump together. The Derjaguin-Landau-Verwey-Overbeek (DLVO) framework is important for fields like water treatment, and nano-technology. It proposes that the total interaction energy between two particles is the sum of two opposing forces namely van der Waals attraction and electro-static repulsion.
DN value – It is the product of bearing bore diameter in millimeters and speed in revolutions per minute.
Doctor blade – It is also called doctor bar. It is a straight piece of material used to spread resin, as in application of a thin film of resin for use in hot melt prepregging or for use as an adhesive film. It is also called paste metering blade.
Doctor blade coating – It is a technique used to form films with well-defined thicknesses by moving a sharp blade across a surface while a coating solution is placed in front of the blade, creating a wet film. This process typically needs high-viscosity inks or pastes, achieved through the addition of binders and thickeners.
Document – It is a written, drawn, presented, or memorialized representation of thought. It is an official piece of writing which gives information, proof or evidence. It is also a computer file which contains text that has a name which identifies it.
Documentation – It enables communication of intent and consistency of action. Its use contributes to (i) achievement of conformity to the process or system requirements and improvement, (ii) provision of appropriate training, (iii) repeatability and traceability, (iv) provision of objective evidence, and (v) evaluation of the effectiveness and continuing suitability of a process or a system.
Document control and compliance – It means managing and controlling of documentation including manuals, procedures, and compliance records. This ensures that the operation and maintenance activities adhere to industry standards and regulatory requirements.
Document control procedure – It establishes methodology for the issuance, maintenance, revision, and distribution of the documents. It also ensures that a person does not refer to any unauthorized document which is not approved.
Document object model objects – These are the programming interface entities which represent the structure, style, and content of a web document as a hierarchical tree of programmable objects. When a browser loads an HTML (hyper-text mark-up language) web page, it interprets the markup and instantiates these memory objects so that scripting languages like JavaScript can read, modify, delete, or create elements dynamically. The document object model (DOM) structure maps a web page into specific object types, organized by inheritance and relationships
Dodecacalcium hepta-aluminate – It is denoted as 12CaO·7Al2O3 or C12A7. It is an inorganic solid with a nano-porous cubic structure. It occurs rarely in nature as the mineral mayenite. It is an important phase in calcium aluminate cements and is an intermediate in the manufacture of Portland cement.
Dodecahedron – It is a three-dimensional geometric shape (a polyhedron) with twelve flat faces. The most common form is the regular dodecahedron, which is one of the five Platonic solids, featuring 12 congruent regular pentagonal faces, 30 edges, and 20 vertices.
Doffer – It is a revolving cylinder, roller, or mechanical device on a carding machine which strips carded fibres from the main cylinder to form a continuous, uniform web. It can also refer to an automated mechanism which removes full bobbins or packages of yarn from spinning machines.
Dog bone – It refers to a flat, symmetrically shaped test sample with a narrow middle section and wider ends used in tensile testing to measure material strength.
Dog-bone coupon – It is also called dumb-bell sample. It is a standardized, specifically shaped piece of material used in tensile testing. It features a narrow, precisely measured center section (the gauge) and wide, flat ends that are clamped securely into testing grips.
Dog bone section – It refers to a component or test sample shaped like a literal dog bone, having wider ends and a narrower middle section. This geometry is intentionally designed to force stress, yielding, or fracture to occur safely within the controlled central region rather than at the grips or joints.
Dogleg severity – It is the total three-dimensional angular changes between survey stations, calculated by dividing the change in angle by the course length between the stations and multiplying by 100. It is important for ensuring that casing and downhole tools can be run without becoming stuck.
Doherty power amplifier – It is a specialized radio frequency (RF) amplifier circuit architecture designed to maintain high power-added efficiency when handling signals with a high peak-to-average power ratio (PAPR). It uses active load modulation between a main (carrier) amplifier and an auxiliary (peaking) amplifier.
Dolly – In filament winding, it is the planar reinforcement applied to a local area between windings to provide extra strength in an area where a cut-out is to be made, e.g., port openings. It is normally placed at the knuckle joints of cylinder to dome.
Doloma (MgO.CaO) – It is an intimate mixture of calcium oxide and magnesium oxide produced by calcination of the naturally occurring or synthetic mixed carbonate or hydroxide. The term ‘dolomite’ is sometimes used to describe doloma material but is the correct term for naturally occurring uncalcined rock. It is being widely used in the manufacture of refractory products because of its favourable properties, such as the ability to refine steel melt, high refractoriness, high corrosion resistance in alkaline environments, as well as its favourable hot strength.
Doloma-carbon refractory – It is a refractory brick manufactured predominantly from a mixture of refractory-grade doloma and 2 % to 20 % carbonaceous materials, with resin, tar, pitch, or a combination of these materials as the bonding agent. The refractory-grade doloma can be either dead-burned dolomite, synthetic doloma, fused doloma, or combinations of these materials, and the carbonaceous material can be either graphite, carbon black, or a combination of these materials.
Doloma, fused— It is refractory-grade material consisting predominantly of lime and magnesia which has solidified from a fused or molten state.
Doloma-magnesia refractory – It is a refractory, which can be burned or unburned, manufactured predominantly of a mixture of refractory-grade doloma and refractory-grade magnesia in which the refractory-grade doloma predominates.
Doloma refractory – It is a refractory manufactured predominantly of dead-burned dolomite, synthetic doloma, fused doloma, or combinations of these materials.
Doloma, refractory-grade – It is a dead-burned or fused refractory material consisting predominately of lime and magnesia. The three principal types are dolomite, dead-burned, doloma synthetic, and doloma fused.
Doloma, synthetic – It is a refractory-grade doloma which has been derived from blending magnesia and lime or dolomite and dead-burning to form a dense, hydration-resistant material, and having a MgO content of 30 % to 80 % and maximum CaO content of 70 %.
Dolomite – Dolomite is a common rock-forming mineral. It is a calcium magnesium carbonate. It is the primary component of the sedimentary rock known as dolostone and the metamorphic rock known as dolomitic marble. Dolomite is a complex mineral with a composition of CaCO3.MgCO3. It is used as fluxing material as well as adjusting the MgO content of the slag.
Dolomite brick – A refractory brick which is manufactured substantially or entirely of dead-burned dolomite.
Dolomite, burnt – When dolomite is heated at a high temperature then it loses its reactivity and the product is known as burnt dolomite. Burnt dolomite is a refractory material and is used in the manufacture of basic refractories.
Dolomite, calcined -It is the calcined dolomite (CaO.MgO) which is produced on heating of dolomite (CaCO3.MgCO3). Calcined dolomite is also known as dolime or doloma.
Dolomite, dead-burned – It is a refractory-grade doloma which is obtained by burning dolomite above 1,450 deg C long enough to form a dense hydration-resistant material composed mainly of lime and magnesia.
Dolomite refractories – These refractories are composed of 50 % MgO to 80 % MgO and are produced with sintered dolomite. Because of these refractories showing a good chemical resistance against basic environments (as slag and fluxes) at high-temperature, good thermal shock resistance, low vapour pressure, thermodynamic stability in the presence of carbon, and a suitable abrasion resistance, magnesia-doloma refractories are widely used in ferrous, non-ferrous and cement industries. However, in spite of these advantageous properties, the application of these refractory bricks has not been popular because of their tendency to hydration when exposed to the atmosphere.
Dolomitic lime – It is the lime having some percentage of MgO (normally 2 % to 4 %).
Dolomitic limestone – It is that limestone which contains some dolomite.
Domain – It refers to a specific sphere of knowledge, activity, or targeted subject area. It defines the boundaries of a project or system, dictating the unique rules, terminology, and requirements involved.
Domain analysis – It is the foundational first phase of domain engineering where experts identify, collect, and organize core requirements, commonalities, and variables across a family of related systems to build reusable assets.
Domain boundary – It establishes precise functional, structural, or organizational limits separating distinct operational regions, applied in software architecture to define ownership, in data engineering to scope trusted datasets, and in materials engineering to design novel interface functionalities.
Domain characterization – It is the process of identifying, analyzing, and defining the core features, boundaries, and variables of a specific operational field or product family. It builds the structural foundation for reusing knowledge and building systems efficiently.
Domain concept – It is a model which includes all aspects of the application domain to be potentially supported by an application system, focusing on tasks, relevant objects, and their interactions.
Domain condition – It refers to the specific operational boundaries, physical limits, or logical rules which define where a system, model, or equation is valid and functions correctly.
Domain configuration – It is the initial phase of domain engineering where system boundaries, common features, and variable parameters are defined. It sets the exact scope, rules, and reusable components for building a specific family of systems or software product lines.
Domain decomposition – It is a divide-and-conquer mathematical technique which splits a large physical or computational problem space into smaller, manageable sub-domains. Solutions are computed independently or concurrently across these regions and coordinated through boundary conditions to solve complex partial differential equations (PDEs) efficiently.
Domain engineering – It is the systematic process of collecting, organizing, and reusing knowledge, requirements, and components from a specific field of activity to build a reusable core asset base for future systems. It defines the core abstractions, rules, and common features of a problem space before individual applications are built.
Domain equalization – It is frequently divided into time-domain or frequency-domain equalization. It is a technique used to reverse signal distortion and remove inter-symbol interference (ISI) caused by a transmission channel. By processing signals within a specific mathematical domain (such as converting time-varying signals through Fourier transforms), the system applies inverse filter characteristics to reconstruct the original transmitted data.
Domain equalizer – It is a signal-processing device or algorithm which adjusts signal gain and phase within a specific processing domain (such as the time domain or frequency domain) to cancel out distortion and minimize inter-symbol interference (ISI).
Domain equation – It is a mathematical rule defined inside a physical domain file which automatically propagates shared physical laws, constraints, or variable definitions to every connected component node.
Domain expert – Domain expert is a specialist with deep, practical, and theoretical knowledge in a specific technical field. Domain experts guide system design, validate real-world constraints, and ensure solutions meet safety and functional standards.
Domain fatigue – It is frequently analyzed through time-domain fatigue analysis. It refers to the evaluation of cumulative structural damage and crack growth in materials subjected to repeating, time-varying loads (such as waves, wind, or vibrations) over a specific operational period.
Domain feature – It is the process of using deep practical knowledge from a specific field to design and build meaningful data inputs for machine learning models. It turns raw, messy data into smart features that help algorithms find hidden patterns and make better predictions.
Domain formation – It is the process where a physical system naturally splits into distinct microscopic regions (domains) with different orientations, polarizations, or compositions. This happens to minimize total system energy, such as magnetostatic or electrostatic stray fields.
Domain function – It specifies the exact operational role, inputs, and outputs of a sub-system within a targeted organizational or technical environment. It establishes clear boundaries for what a component does, what data it accepts (its domain), and what results it yields (its range) to align system architecture with real-world requirements.
Domain geometry – It is the precise shape, size, and spatial boundary of a physical system or mathematical space under analysis. It defines the exact physical limits where forces, fluid flows, heat transfers, or electro-magnetic fields are calculated during computer simulations or design work.
Domain information – It refers to the specific details, rules, attributes, or metadata which define a particular subject area, database field type, or website address. In computer science, it refers to a set of attributes assigned to each data type, including data type, length, date format, range, constraints, null support, and default value, ensuring the validity and integrity of values in a database.
Domain integral method – It is a computational technique which converts a contour integral (such as the J-integral) into an equivalent area (2D) or volume (3D) integral over a finite domain surrounding a crack tip or front.
Domain intensity – It typically refers to the local magnitude, energy flux density, or strength of a physical quantity (such as acoustic, structural, or optical energy) mapped across a specific spatial, temporal, or frequency region (domain).
Domain knowledge – It means the specialized, real-world understanding of a specific industry or field rather than just general technical or programming skills. It covers the rules, work-flows, challenges, and standards needed to build practical solutions.
Domain, magnetic – It is a substructure in a ferromagnetic material within which all the elementary magnets (electron spins) are held aligned in one direction by inter-atomic forces. If isolated, a domain is a saturated permanent magnet.
Domain measurement – It defines how a signal or system characteristic is observed and quantified relative to a specific reference frame, very frequently time or frequency. It dictates whether data is analyzed as a wave changing over elapsed seconds or as constituent sine-wave components spread across various hertz.
Domain method – It normally refers to the domain of a function, which is the complete set of all possible input values (often called x-values) that a function can accept to produce a real, valid output.
Domain model – It is a visual and conceptual design of real-world objects, rules, and relationships for a specific problem area. It combines both the data and the logic into a single structure, independent of databases or user interfaces.
Domain name – It is the website’s human-readable address on the internet (e.g., google.com). It replaces the complex numerical IP (internet protocol) addresses which computers use to communicate, making it much easier for people to find and remember the web-site.
Domain point – It typically refers to a specific metric, feature coordinate, or data value within a defined problem space or domain model. It can denote a discrete coordinate in numerical simulations, a feature landmark in domain analysis, or a definition point in program analysis.
Domain reflectometry – It is a measurement technique used to characterize electrical or optical lines. It sends a signal down a medium and analyzes the returned echoes to find faults, breaks, or changes in impedance.
Domain representation – It means describing a system, signal, or problem space using a specific mathematical or conceptual framework, such as the time domain or frequency domain, to make analysis and design simpler.
Domain response – It refers to how a system or structure reacts to an input signal or load when analyzed within a specific mathematical framework, very frequently the time domain (tracking changes over time) or the frequency domain (tracking changes across frequency components).
Domain, signal – Signal domain refers to the mathematical or physical coordinate system, very frequently time or frequency, used to measure, visualize, and analyze how a signal’s properties change. It defines the perspective through which data or wave-forms are evaluated.
Domain size – It has distinct meanings depending on the specific technical field. It very frequently refers to the physical dimensions of a structured magnetic or crystalline region, the volumetric boundary limits in a computer simulation, or the characteristic length scale in material micro-structures.
Domain structure – It refers to the systematic organization, hierarchical arrangement, and modelling of shared concepts, rules, and reusable assets (like software code, requirements, and architectures) for a specific industry or problem space. It acts as a master blue-print which maps out commonalities and variabilities so teams can build multiple related systems efficiently rather than starting from scratch.
Domain surface – It refers to the outer boundary or interface of a specific computational, geometric, or physical region which separates distinct material phases, states, or analysis zones. It also defines the exact topographical and chemical boundary limits altered for wear and corrosion resistance.
Domain theory – It can refer to a mathematical framework for computer semantics, a systems approach to product design, or a method for structuring application knowledge.
Domain transfer function – It is the mathematical ratio of the output signal’s transform to the input signal’s transform for a linear time-invariant (LTI) system, assuming zero initial conditions. It translates complex differential equations into simple algebraic functions of a complex frequency variable.
Domain velocity – It is also called domain velocity field. It is a vector field which defines how material points or coordinates inside a geometric domain move and update when the shape of the system changes during design iterations, optimization, or deforming mesh simulations.
Domain velocity field – It is a mathematical description which assigns a vector velocity to every spatial point within a defined geometric region (domain) over time. It maps how fast and in what direction a continuous medium, such as a flowing fluid or a deforming structure, moves across that space.
Domain version – It refers to an implementation of algorithms, such as the filtered-reference and filtered-error LMS (least mean square) algorithms, within a specific domain, either time or frequency, allowing for distinct computational efficiencies and the ability to address certain limitations inherent in the alternative domain.
Domain wall – It is a narrow transition boundary separating adjacent micro-regions, known as domains, where a physical property like magnetic magnetization or electric polarization points in different directions. These interfaces span a finite width of atomic layers and dictate how materials respond to external magnetic fields or voltages.
Domain wall dynamics – It refers to the study and control of how the thin boundary layers separating different uniform structural, magnetic, or electric domains move and change within a material. In functional materials like ferro-magnets or ferro-electrics, these moving boundaries dictate how the material responds to external forces, magnetic fields, or electric currents.
Domain wall pinning – It is the process where boundaries between different magnetic or electric domains are trapped or hindered from moving by material defects, structural notches, or grain boundaries. This trapping creates local energy minima which need an external magnetic field or electrical voltage to overcome and release the wall.
Dome – In filament winding, it is the portion of a cylindrical container which forms the spherical or elliptical shell ends of the container. Dome is also the roof of a furnace which is roughly hemispherical in shape. It is also the steam chamber of a boiler. In geology, dome is a feature in structural geology where a circular part of the earth’s surface has been pushed upward, tilting the pre-existing layers of earth away from the centre. In technical terms, it consists of symmetrical anticlines that intersect each other at their respective apices. Intact, domes are distinct, rounded, spherical-to-ellipsoidal-shaped protrusions on the earth’s surface. A slice parallel to earth’s surface of a dome features concentric rings of strata.
Dome, hot blast stove – The dome area of the hot blast stove is divided into a working layer, a filling layer and a heat insulating layer. Maintenance of the structural stability of the dome at the high temperatures is important. The dome evenly distributes high-temperature flue gas into the regenerator during combustion. The temperature of the dome area is very high. It is around 1,400 deg C in conventional stoves and around 1,550 deg C in high temperature modern stoves. The refractories used in the working layer are mostly silica brick, mullite brick, andalusite brick, low creep high alumina brick. In the outside of the working layer insulation refractory bricks are used.
Dome shape – It refers to either the outward convex curvature of sheet metal formed during stretch-testing (to evaluate ductility) or miniature, elastic metallic switch components (snap domes). The term also describes the physical geometry of specialized industrial vessels.
Domestic consumption – It means the use of goods and services within the country where they are produced.
Domestic production – It is the total value of all finished goods and services made inside a country during a set time, normally one year or one quarter. It counts all economic activity by local and foreign organizations inside the nation.
Domestic water – It is the water which is used for washing and in wash rooms. In industrial plants normally drinking water is used as domestic water.
Domfer process – It refers to a proprietary method used by Domfer Metal Powders Ltd. to manufacture high-purity iron and steel powders for powder metallurgy (P/M). The process typically combines water atomization and solid-state gaseous reduction to produce specialty powders used in structural components, welding, and friction materials.
Dominant eigenvalue – It is the largest eigenvalue (in absolute value) of a matrix, which is particularly important for numerical techniques like the ‘power method’ used to find it along with a corresponding eigenvector.
Dominant eigenvector – It is a special vector linked to the eigenvalue which has the largest absolute magnitude in a system. When a matrix transforms this vector, it scales it more than any other vector. It dictates the primary or long-term behaviour of a physical or mathematical system.
Dominant fuel – It is the main energy source utilized in a system, power plant, or grid, chosen predominantly for its high abundance, economic cost-effectiveness, and reliable thermal output relative to alternative options.
Dominant object – It refers to a primary data element, shape, or rule variable which controls the execution state, structural hierarchy, or spatial focus within a system. It dictates how algorithms process rules, prioritize shapes, or evaluate multi-criteria models.
Dominant wave-length – It is the single pure spectral colour wave-length which the human eye perceives from a light mixture. Iit matches a complex light source or LED (light emitting diode) output by connecting a chromaticity diagram’s white point to the sample’s colour coordinate and extending it to the outer spectral locus.
Dominated application – It refers to a primary operational state where one specific physical force, design constraint, or market factor vastly outweighs all others, dictating the system’s core behaviour, governing equations, and performance limits.
Dominated condition – It normally describes a system or process where one specific physical force, failure mode, or environmental boundary exerts main control over the system’s behaviour, rendering other secondary variables negligible.
Dominant failure mode – It is the main, governing path or physical process by which a structure, material, or system loses its ability to function. When multiple stresses act on a component, the dominant failure is the one which outpaces the others and dictates ultimate breakdown.
Dominated mechanism – It refers to a physical process, deformation mode, or system behaviour where one primary governing factor, force, or operational mode overrides considerably all competing alternatives in dictating the system’s overall response.
Dominated scenario – It refers to an operational or structural condition where one primary factor (such as supply, demand, stress, or environmental load) overwhelmingly dictates the behaviour, capacity, or failure mode of the entire system.
Dominated structure – It is normally categorized as stretch-dominated structure or bending-dominated structure. It refers to a cellular or lattice architecture whose mechanical behaviour and stress responses are controlled mainly by one specific type of internal loading deformation.
Dominic method – It is a qualitative method for evaluating and choosing between alternative design concepts or materials. The method uses an evaluation table in which the evaluation criteria are grouped as per the priority (high, moderate, low), and the alternative solutions are ranked as excellent, good, fair, poor, or unacceptable.
Domino effect – It is a cascading chain reaction where a primary accident, such as a localized fire, explosion, or equipment failure, triggers secondary events in neighbouring units. This escalation results in an overall disaster much more severe than the initial incident.
Donnan dialysis – It is a separation process that utilizes counter-diffusion of ions through an ion-exchange membrane to achieve separation, frequently used for continuous deionization and several other applications such as water softening and pollution control.
Donnan effect – It is also called Gibbs-Donnan effect. It describes the unequal distribution of charged ions across a semi-permeable barrier. This happens when a large, non-diffusible charged molecule is trapped on one side, forcing smaller movable ions to rearrange unevenly.
Donnan equilibrium – It is the unequal distribution of charged ions across a semi-permeable membrane when at least one large, charged ion cannot cross the membrane. This state balances chemical concentration forces with electrical forces. It is widely used in chemical, environmental, and materials engineering fields.
Donnan exclusion – It is the mechanism by which an ion exchange resin can be made to act like a semi-permeable membrane between an interstitial liquid and a liquid occluded inside the resin particles. Highly ionized molecules are excluded from the resin particles by electrostatic forces. Weakly ionized or non-ionized molecules can pass through the membrane.
Donnan exclusion effect – It is an elect-static phenomenon where ions with the same charge as a fixed membrane surface (co-ions) are repelled and blocked from passing through pores, while oppositely charged ions (counter-ions) are allowed to pass. This principle governs permselectivity in water purification, energy storage, and chemical separation systems.
Donnan-steric-pore model – It is a framework used to predict how ions and molecules move through nano-filtration and reverse osmosis membranes. It combines steric (size-based) exclusion and Donnan (electrical charge-based) exclusion to explain liquid filtration and solute rejection.
Donor level – It refers to energy levels created by impurities in the band gap of n-type semi-conductors which are close to the conduction band, allowing electrons to be easily excited into the conduction band and acting as majority carriers for current flow.
Donor state – It refers to a specific, localized energy level created within the band gap of a semi-conductor or insulator by the presence of dopant atoms or impurities.
Dopant – It is a trace impurity intentionally added to a pure base material, very frequently a semi-conductor like silicon, to precisely modify its electrical, optical, or structural properties. Without dopants, basic materials cannot carry enough current to build functional micro-chips.
Dopant activation – It is the thermal process of moving impurity atoms into correct crystal spots in a semi-conductor. This action releases free charge carriers and fixes crystal damage caused by ion shooting.
Dopant atoms – These are impurity atoms deliberately introduced into a pure semiconductor to modify its electrical properties, making it suitable for electronic devices like diodes and transistors. This process, known as doping, creates either excess electrons (n-type doping) or holes (p-type doping), improving conductivity.
Dopant concentration – It refers to the quantity or ratio of dopant atoms to host atoms in a material, normally a semi-conductor. It is a measure of how much a material has been doped with impurity atoms to alter its electrical properties.
Dopant density – It is the number of impurity atoms added per unit volume in a semi-conductor material. It controls how well the material conducts electricity by setting the number of free charge carriers. It is measured in atoms per cubic centimeter.
Dopant ion – It is a specific impurity atom added to a pure semi-conductor material (like silicon) to change how it conducts electricity. These charged atoms are used to build core micro-electronic parts like transistors and diodes.
Doped fibre amplifier – It is an optical device which uses a specialized fibre core infused with rare-earth ions to boost weak light signals directly. It amplifies the signal through stimulated emission through optical pumping, by-passing the need to convert light into electrical signals.
Doped fibre laser – It is an advanced optical system where the active gain medium is an optical fibre core infused with low levels of rare-earth elements like erbium, ytterbium, or thulium. It uses pump diode lasers to excite dopant ions, generating a focused, coherent laser beam inside a resonant cavity.
Doped GaAs (gallium arsenide) – It is a compound semi-conductor intentionally mixed with small quantities of impurity atoms to control its electrical behaviour. This process lowers resistance, adds free electrons or holes, and creates high-speed paths for power and signals used in radio and laser tech.
Doped germanium – It is the intentional addition of impurity atoms into a pure germanium crystal lattice to control its electrical conductivity, carrier type, and optical properties for high-speed electronics and infra-red optics.
Doped glass – It is a base glass matrix intentionally modified with precise trace quantities of impurity elements, such as rare-earth ions, transition metals, or semi-conductor nano-particles. This controlled addition alters optical, electrical, or thermal traits without destroying the amorphous structure.
Doped layer – It is a specific stratum within a semi-conductor material or crystal substrate intentionally altered by adding trace impurity atoms, known as dopants, to precisely control electrical, optical, or thermal conductivity.
Doped nano-tube – It is a carbon nano-tube modified by adding foreign atoms or molecules into its lattice or onto its surface. This intentional impurity shifts the Fermi level, alters charge transport, and improves electrical, chemical, or mechanical performance for advanced engineering applications.
Doped phosphor – It is a luminescent solid material which emits visible or invisible light when excited by an energy source like electrons, UV (ultra-violet) rays, or blue light. It consists of a solid host crystal matrix mixed with a tiny amount of impurity atoms, called activators (such as rare-earth or transition-metal ions).
Doped wave-guide – It is an optical or micro-wave channel structure infused with specific impurity atoms (dopants) to actively modify its refractive index or add gain, lasing, and switching properties. These active impurities transform passive routing paths into functional micro-optic devices like amplifiers and lasers.
Doping – It is the process of intentionally adding impurities to a pure semi-conductor material to modify its electrical properties. This process is used to create specific types of semi-conductors, like n-type and p-type, which are crucial for building electronic devices.
Doping density – It is the number of impurity atoms added to a pure semi-conductor material per unit volume. Engineers use it to control electrical conductivity and make devices like transistors and diodes. It is normally measured in atoms per cubic centimeter.
Doping dependence – It means how a material’s physical, electrical, or optical properties change when people alter the quantity of impurity atoms (dopants) added to it. This relationship is studied to control and tune semi-conductor performance for chips and devices.
Doppler broadening – It is the spreading of spectral lines (in light, sound, or neutron absorption) caused by the random thermal motion of emitting or absorbing particles. Since particles move at different velocities, their individual Doppler shifts blend together, resulting in a widened and less distinct cumulative line profile.
Doppler data – It refers to the frequency shift or phase change measurements extracted from wave signals (such as radio, micro-wave, or ultra-sound) reflecting off moving targets. This data is processed to calculate an object’s relative velocity, direction, and radial speed.
Doppler effect – It is the change in the observed frequency of an acoustic or electro-magnetic wave because of the relative motion of source and observer.
Doppler frequency shift – It is the change in frequency of a wave (such as sound, light, or radio waves) caused by relative motion between a wave source and an observer or reflector. It measures the difference between transmitted and received frequencies to calculate object velocity.
Doppler global velocimetry – It is also known as planar doppler velocimetry (PDV). It is a non-intrusive optical measurement technique used in fluid dynamics and engineering to capture whole-field velocity vectors of seeded flows by analyzing the frequency shift of laser light scattered by moving particles.
Doppler imaging – It is a non-invasive measurement and visualization technique which uses the Doppler effect to detect motion and velocity. It maps frequency shifts of reflected waves (such as ultra-sound or laser light) off moving targets, like fluid particles, into real-time directional colour maps or velocity graphs.
Doppler log – It is an electronic navigation tool which uses the acoustic Doppler effect to measure a vessel’s speed and distance relative to the sea-bed or water column. It transmits ultra-sonic sound waves at an angle and measures the frequency shift of the reflected echoes.
Doppler method – It utilizes the Doppler effect to calculate the velocity and direction of moving objects by measuring the change in frequency (Doppler shift) of reflected or emitted waves.
Doppler method of flow measurement – It uses the Doppler effect to determine the velocity of a flowing fluid. It emits an ultrasonic signal, and the frequency shift in the reflected signal, caused by the moving particles or bubbles in the fluid, is used to calculate the flow rate. This method is particularly useful for measuring flow in liquids with suspended particles or bubbles.
Doppler radar – It is an active remote-sensing system which transmits radio frequency or micro-wave signals and measures the radial velocity of targets by analyzing the frequency shift (Doppler effect) embedded in the backscattered echo.
Doppler resolution – It is a system’s ability to tell apart two or more moving objects which are at the same distance (range) but moving at different speeds. It is measured as the smallest difference in frequency or speed that the system can cleanly separate.
Doppler shift – It is the quantity of change in the observed frequency of a wave because of the Doppler effect. It is normally expressed in hertz.
Doppler spectrum – It is the distribution of signal frequencies shifted by relative motion. It displays the range of frequency values produced when waves bounce off moving objects or pass through dynamic channels.
Doppler spread – It is a measure of the spectral broadening caused by time-varying changes in a communication channel, such as the relative motion between a transmitter and a receiver. When a single-frequency signal is transmitted, this motion causes it to ‘smear’ across a range of frequencies at the receiver.
Doppler velocimeter – It is a non-contact instrument which measures the speed and direction of moving fluids or surfaces. It works by detecting the frequency shift of waves, such as laser light or sound waves, reflected or scattered by moving particles.
Doppler velocimetry – It is an analytical technique used to measure the speed and direction of a moving object or fluid by detecting the frequency shift (the Doppler effect) of reflected waves, such as laser light or sound, bouncing off the moving target. Different fields apply this principle using distinct technologies.
Doppler velocity – It is the measurement of an object’s speed relative to a source by calculating the frequency shift (Doppler effect) of reflected acoustic, laser, or radio waves. It quantifies how fast a target moves toward or away from a sensor.
Dor bar – It is the final saleable product of a gold mine. It is normally consisting of gold and silver.
Dore – It is unrefined gold, normally in bar form and consisting mainly of gold with smaller quantities of other base metals, which is to be further refined to high purity gold bullion.
Dormant crack – It is also called static or dead crack. It is a stable fissure in a material or structure which has completely stopped moving, growing, or changing in width, depth, and length.
Dorn creep – It normally refers to Harper–Dorn creep. It is a low-stress, high-temperature dislocation climb-controlled deformation mechanism in crystalline materials, or to the Sherby–Dorn parameter used in predicting material creep life.
Dosage hydrate inhibitor – It is frequently a low-dosage hydrate inhibitor (LDHI). It is a chemical used in oil and gas pipelines. It stops ice-like gas crystals from forming and blocking sub-sea flow lines. Unlike old methods which need heavy truckloads of chemicals, it works at very low doses.
Dose – It is the measurement characterizing the exposure of individuals subjected to radiation. The term dose is frequently mistakenly used instead of dose equivalent. The absorbed dose is the quantity of energy absorbed by matter (living or inert) exposed to radiation. It is expressed in Grays (Gy). Dose equivalent in living organisms is an absorbed dose which has different effect depending on the type of radiation (alpha, beta and gamma). For taking these differences into account, a dose-multiplying factor is used to produce a ‘dose equivalent’. Effective dose is the sum of weighted dose equivalents deposited on various tissues and organs by internal and external irradiation. The unit of measurement for effective dose is the Sievert (Sv). Lethal dose is the fatal dose of nuclear or chemical origin. Maximum permissible dose is the dose which is not to be exceeded for a given period of time.
Dose limitation – It is the process of limiting radiation doses to individuals. It is also known as the third radiation protection principle.
Dose rate – The dose rate is the quotient of dose and time. For example, rem (roentgen equivalent man) per hour or Sieverts per hour.
Dosimeter – It is the instrument for measuring absorbed dose. It is used to detect and measure an accumulated dosage of radiation. In common usage, it is a pencil-size ionization chamber with a built-in self-reading electrometer. It is used for personal monitoring.
Dosimeter, pocket – Pocket dosimeter is a portable, pen-sized device used to continuously measure and display a worker’s cumulative exposure to ionizing radiation (such as X-rays and gamma rays). These dosimeters are mainly worn by personnel performing industrial radiography (non-destructive testing) to inspect heavy castings for internal flaws or weld defects.
Dosimetry – It is the theory and application of the principles and techniques involved in the measurement and recording of ionizing radiation doses. What is calculated is the absorbed dose in matter and tissue resulting from the exposure to ionizing radiation.
Dosing point – It is the exact physical location where a specific chemical, reagent is introduced into a larger system, process stream, or container.
Dosing pump – It is a small, specialized positive displacement pump used to inject a precise, measured volume of liquid chemical or other substance into a water, gas, or steam stream at specific time intervals.
Dot layer – It is short for quantum dot layer. It is an ultrathin film of semi-conductor nano-crystals (2 nano-meters to 10 nano-meters in size) sandwiched between charge-transport layers to absorb or emit pure, size-tuned light via carrier recombination.
Dot map – It is an intensity map (normally corresponding to an image) in which the intensity in any area is proportional to the concentration of a specific element in that area.
Dot plot – A dot-plot is an alternative to a boxplot where each value is recorded as a dot. It is used when there are only few data values. The dots can be jittered, so each value is made visible. They can alternatively be stacked, to produce a simple histogram.
Dot product – It is defined as the scalar result of the sum of the products of corresponding components of two vectors, representing the projection of one vector onto another. It is calculated only between vectors of the same dimensionality and is connected to the cosine of the angle between them.
Dotted line – It is a series of dots forming a path. It frequently marks where to sign a contract, shows a cut or fold on paper, or represents secondary work links in organization.
Double acceptor – It is also called dual-acceptor engineering. It refers to two distinct concepts depending on the field namely semi-conductor impurity doping (where an impurity can accept two electrons / create two holes) or molecular backbone design (incorporating two electron-withdrawing groups).
Double acting actuator – It is an actuator which requires power in both operating directions i.e., no spring.
Double-acting hammer – It is a forging hammer in which the ram is raised by admitting steam or air into a cylinder below the piston, and the blow intensified by admitting steam or air above the piston on the downward stroke. Double acting hammers are similar to gravity hammers in that a lifting cylinder raises the moving tup, but power is also applied to the downward-moving tup to increase the energy capacity. Energy ratings for similar tup weights are considerably more than for gravity hammers, and the die closing speeds are higher also. Power comes from double-acting steam, compressed air, or hydraulic cylinders.
Double-action deep drawing process – It is also known as deep draw stamping. It is a specialized sheet metal forming method where a flat metal blank is shaped into a hollow, 3-dimensional part by a punch and die, while an independent blank holder prevents the metal from wrinkling or tearing.
Double-action die – It is a die designed to perform more than one operation in a single stroke of the press. Double-action dies are specialized press tools used in sheet metal forming where blanking and drawing punches operate independently, driven by two separate slides in a double-action press. This dual-action mechanism prevents tearing and wrinkling, making it ideal for deep drawing complex, three-dimensional shapes.
Double-action drawing – It is frequently referred to as double-action deep drawing. It is a specialized sheet metal forming process used to shape flat metal blanks into hollow, three-dimensional cup or box-shaped components. It relies on two independent press movements to control the metal’s flow and prevent defects.
Double-action forming – It consists of forming or drawing in which more than one action is achieved in a single stroke of the press.
Double-action mechanical press – It is a press having two independent parallel movements by means of two slides, one moving within the other. The inner slide or plunger is normally operated by a crankshaft; the outer or blank-holder slide, which dwells during the drawing operation, is normally operated by a toggle mechanism or by cams.
Double-action press – It is a specialized machine featuring two independent, concentric slides or rams (an inner and an outer ram). It is mainly designed for deep drawing, where the outer ram acts as a blank holder to hold the metal sheet flat (preventing wrinkles), while the inner ram punches the material into the die.
Double-action tooling system – it refers to a powder compaction setup where pressure is applied to the metal powder from both the top and the bottom using independent punches. This method ensures uniform density and structural integrity throughout the compacted ‘green’ part.
Double aging – It consists of employment of two different aging treatments for controlling the type of precipitate formed from a super-saturated matrix in order to get the desired properties. The first aging treatment, sometimes referred to as intermediate or stabilizing, is normally carried out at higher temperature than the second.
Double annealing – It is a specialized, two-stage heat treatment used mainly for steel castings to eliminate coarse, brittle grain structures, such as the Widmanstätten structure, and fix severe chemical segregation.
Double basket hitch – It consists of two single basket hitches placed under the load. On smooth surfaces, the legs tend to draw together as the load is lifted. For countering this, the hitch is braced against a change in contour, or other reliable means, to prevent the slings from slipping. It is also necessary to keep the legs far enough apart to provide balance, but not so far apart that they create angles of less than 60-degree with the horizontal.
Double-beat valve – It is also called drop valve or equilibrium valve. It is a type of poppet valve arranged to allow it to be opened against a high pressure with a minimum of force.
Double bevel groove weld – It is a joint configuration where the edge of one joining member is angled from both sides, forming a ‘K’ or double ‘Y’ cross-section. It is specifically designed to achieve full penetration in thick materials while minimizing the needed volume of weld filler metal. It is typically used on T-joints or butt joints when one plate remains flat and the mating piece is beveled on both the top and bottom edges.
Double-block accumulating machine – It is a specialized continuous wire-drawing machine. It utilizes two vertically stacked, individually driven coiling ‘blocks’ to temporarily store, accumulate, or deplete wire between separate drawing dies without causing twisting, tangling, or slippage.
Double-block accumulating wire drawing machine – It is a specialized piece of metallurgical equipment used to reduce the diameter of metal wire (like copper, aluminum, or steel). It features two drawing drums (blocks) and an accumulation / dancer system which briefly stores the wire between the dies, ensuring continuous operation and consistent tension.
Double block and bleed valve – It is a valve with two seating surfaces that in the closed position provides a seal against pressure from both ends of the valve with a mean of venting / bleeding the cavity between the seating surfaces.
Double bond – It is a bond involving the covalent sharing of two pairs of electrons.
Double bottom tank – It is a secondary containment or structural configuration featuring two complete bottom layers. It is used either in land-based industrial storage tanks to catch leaks or integrated into marine vessel hulls to provide safety, structural strength, and liquid storage.
Double bubble process – It is a manufacturing method used to make bi-axially oriented (stretched in two directions) polymer films. It cools a primary extruded tube (the first bubble), reheats it, and reinflates it with air (the second bubble) to balance strength and shrink properties.
Double burned – It is also referred to as dead-burned. It is a term applied to refractory materials (such as fire-bricks or dolomitic lining) which have been calcined at extremely high temperatures. This heavy-duty treatment creates a highly dense, chemically stable product which is highly resistant to heat, atmospheric moisture, and subsequent contraction.
Double cantilever beam – It is a test sample and analytical model used in fracture mechanics. It consists of two identical parallel arms or beams joined together with a pre-cracked mid-plane interface. Engineers pull the free ends apart with opening tensile loads to study Mode I crack growth and measure fracture toughness.
Double cantilever beam (DCB) test – It is a standard fracture mechanics method used to measure Mode I (tensile opening) fracture toughness, critical strain energy release rate (GIc), and crack growth behaviour in bonded joints, laminates, and structural materials.
Double-clamped beam – It is also called a fixed beam. It is a structural element which is rigidly fixed or clamped at both ends. This complete restriction at both supports prevents both vertical movement and rotational bending.
Double cold reduced steel – It is a specialized, thin, high-strength steel mainly used for tin mill products like tinplate or tin-free steel. It is made by partially rolling steel to an intermediate thickness, annealing it to restore flexibility, and cold-rolling it a second time to its final gauge.
Double cold reduction – It is a steel manufacturing process where a metal strip undergoes a second cold rolling pass after initial reduction, annealing, and cooling. This technique strain-hardens the material, creating ultra-thin, high-strength metal commonly used in packaging materials like lightweight tinplate.
Double cold reduction (DCR) mill – It is a specialized two-stand steel processing facility which performs thickness reduction in the first stand and skin-passing (temper rolling) in the second. Typically used for manufacturing tinplate, this process creates thinner, harder, and stronger steel sheets while achieving precise surface characteristics and uniform flatness.
Double cold reduction (DCR) temper mill – It is a specialized two-stand facility used to thin annealed steel strips while dramatically increasing their hardness and strength. It combines substantial thickness reduction in the first stand with skin passing in the second, mainly manufacturing light-gauge materials like tinplate.
Double cup backward extrusion test – It is a standardized physical and numerical method used to evaluate interfacial friction, material flow, and lubricant efficiency during high-deformation bulk metal forming processes. In this test, a cylindrical metal billet is placed into a die and compressed simultaneously by an upper and lower punch. This creates both a forward and a backward extrusion of metal, forming a shape resembling two cups.
Double diamond model – It is a visual framework used in product development and problem-solving. It splits work into four phases namely discover, define, develop, and deliver, moving between wide and narrow thinking.
Doubled die – It is also known as hub doubling. It is a term in numismatics used to refer to a duplication of design elements on a working die created because of a misalignment of the die or hub during the hubbing process. Strength of the doubling can vary from very slight and isolated to extreme and widespread. The exact cause of the doubling can also vary, which is why a class system was created to outline the known and hypothesized causes.
Double dipping – It is the process of dipping steel, which is too large in one dimension to completely fit into the galvanizing pot, more than once in cleaning solutions and molten zinc metal in order to produce a coating which covers the entire surface of the steel. Fabricated items longer or wider than the galvanizing bath in one dimension can be galvanized by double dipping, where one side or end of the fabrication is galvanized first. The fabrication is then rotated or turned over allowing the second section to be galvanized.
Double-effect absorption cooling system – It is an advanced thermal refrigeration cycle which uses two generator stages and a lithium bromide-water (LiBr-H2O) working fluid to produce chilled water. By reusing heat released from a high-pressure generator to drive a second generator, it achieves a high coefficient of performance (COP of 1.3 to 1.4), nearly doubling the efficiency of single-effect designs.
Double-end upsetting – It is a metal-working process where a forging machine applies compressive force to both ends of a metal bar, rod, or tube, forcing the material to expand laterally (or ‘upset’) to create enlarged, structurally reinforced sections. Unlike single-end forging, it involves two distinct upsetting operations performed on opposite ends of the stock to form complex shapes like spool bolts or specialized fittings.
Double etching – In metallography, is consists of the use of two etching solutions in sequence. The second etchant emphasizes a particular micro-structural feature.
Double-exponential function – It defines a transient wave-form, such as a lightning strike, electrostatic discharge (ESD), or nuclear electromagnetic pulse (high-altitude electro-magnetic pulse or HEMP), expressed as the difference between two exponential decay terms [f(t) = K(‘e’ to the power -alpha ‘t’ – ‘e’ to the power -beta ‘t’)], where alpha and beta govern the rise and fall times.
Double exponential model – It normally describes wave-forms (like lightning strikes or voltage pulses) using the difference of two exponential decay terms, or a function growing at an accelerated double-exponential rate.
Double-exposure holographic interferometry – It ts a non-destructive testing method where a hologram of a metal sample is recorded in its initial, unstressed state, and a second hologram is recorded on the same plate while the sample is mechanically stressed (e.g., loaded or heated).
Double exposure lithography – It is a two exposure pass lithographic process which does not need the removal of the wafer from the exposure tool chuck between passes.
Double-exposure strategy in metal additive manufacturing – In powder bed fusion or laser welding processes, this refers to exposing a specific layer of metal powder or metal surface to the laser energy source twice.
Double-exposure technique (DET) for residual stress – In X-ray diffraction (XRD), this is an analytical method used to measure residual stresses in poly-crystalline metals. It involves taking two diffraction measurements at different angles of inclination relative to the sample surface. It enables rapid calculation of the lattice strain, allowing metallurgists to quantify the internal stresses (tensile or compressive) left behind by manufacturing processes like welding.
Double-extension dies – These are dies which are extended at both ends to provide a longer taper section.
Double flare bevel groove weld – It is a weld in grooves formed by a member with a curved surface in contact with a planar member.
Double flare V-groove weld – It is a weld in grooves formed by two members with curved surfaces.
Double-flash power plant – It is an advanced geothermal energy facility which extracts high-temperature underground water and passes it through two sequential pressure-reduction stages. This dual-flashing process converts leftover hot brine into low-pressure steam, boosting overall electricity generation by 15 % to 25 % compared to single-flash configurations.
Double-flash system – It is an advanced geo-thermal power setup. It uses two separate pressure stages (flash tanks) to turn hot underground water into steam. This extra step squeezes out more energy and yields about 25 % more power than a single-flash system.
Double fluid filter – It is dual-chamber fluid filter. It is a parallel filtration set-up featuring two distinct filter chambers connected by a change-over valve. This design allows one chamber to actively filter liquid while the other is isolated for cleaning or replacement, ensuring uninterrupted fluid flow.
Double-hard peening – It is very frequently referred to as dual or double shot peening. It is a two-stage shot peening process. It applies a high-intensity peening pass using large, hard media to establish deep compressive stress, followed by a low-intensity pass with fine, ultra-hard media (like glass or ceramic) to maximize surface hardness and smoothness.
Double helical gears – In these gears, thrust loading is eliminated by using two pairs of gears with tooth angles opposed to each other. In this way, the side thrust from one gear cancels the thrust from the other gear. These opposed gears are normally manufactured with a space between the opposing sets of teeth.
Double impression method – It is frequently called the double ball method. It is a technique to determine the approximate Brinell hardness of a metal part when standard laboratory testing equipment is not available or suitable.
Double inclined shaft kilns – This type of kiln (Fig 6) can produce a reactive low carbonate product. It is essentially rectangular in cross-section but incorporates two inclined sections in the calcining zone. Opposite each inclined section, offset arches create spaces into which fuel and preheated combustion air are fired through the combustion chambers. Cooling air is drawn into the base of the kiln where it is preheated, withdrawn and re-injected through the combustion chambers. The circuitous paths for both the gases and the burden, coupled with firing from both sides, ensure an efficient distribution of heat. A range of solid, liquid and gaseous fuels can be used, although they are to be selected with care to avoid excessive build-ups caused by fuel ash and calcium sulphate deposits.
Double inverted pendulum – It is a complex mechanical system with two rigid links connected in series by joints, where the first link connects to a movable or fixed base (such as a motorized cart) and its centre of mass sits above the pivot point. Since it is heavily unstable, non-linear, and under-actuated, it is used as a benchmark test for advanced control algorithms.
Double-isolation and bleed valve – It is a single valve with two seating surfaces, each of which in the closed position provides a seal against pressure from a single source, with a means of venting / bleeding the cavity between the seating surfaces. This feature can be provided in one direction or in both directions.
Double J-groove weld – It is a type of groove weld.
Double lap joint – It is a symmetrical mechanical or adhesive connection where a main central plate is sandwiched between two outer cover plates, creating two overlapping regions. This symmetrical load path eliminates secondary bending moments, reduces peel stresses, and doubles the shear capacity compared to a single lap joint.
Double layer – It is the interface between an electrode or a suspended particle and an electrolyte created by charge-charge interaction leading to an alignment of oppositely charged ions at the surface of the electrode or particle. The simplest model is represented by a parallel plate condenser.
Double-layer capacitor – Electric double-layer capacitor (EDLC) normally called a super-capacitor or ultra-capacitor. It is an electro-chemical energy storage device which stores energy statically through ion adsorption at the microscopic boundary between a porous electrode and a liquid electrolyte, yielding extremely high capacitance in a small volume.
Double layer thickness – It is the characteristic distance which an electrical double layer extends from a charged surface into a liquid solution. It acts as a measure of how far electric forces reach in a fluid. It is equal to the Debye length.
Double logarithmic coordinates – It is a log-log plot. These coordinates feature a graph where both the horizontal (x) and vertical (y) axes use logarithmic scales. This system turns non-linear power functions (y = a x to the power ‘b’) into straight lines. This makes it easy to find scaling laws, constants, and exponents from experimental data.
Double-looping – In a sheet slitting line, it consists of a combination of pre-looping and post-looping. It offers the advantages of both (pre-looping as well as post-looping) to ensure minimal strip damage.
Double mechanical seal – It is a shaft-sealing device using two sets of mechanical seals arranged in series with a liquid or gas fluid chamber in between. It prevents hazardous, toxic, or abrasive fluids from escaping into the environment by using an independent buffer or barrier fluid to lubricate and cool the seal faces.
Double-network hydrogel – It is a water-swollen material made of two intertwined polymer networks. One rigid, tightly cross-linked network provides strength, while a second soft, loosely cross-linked network adds stretch. This design uses sacrificial bonds that break under stress to stop cracks from growing.
Double patterning lithography – It is a two exposure pass lithographic process which needs a chemical development of the photoresist layers and possibly an intermediate etch step. The double patterning lithography (DPL) processing approaches need the removal of the wafer from the exposure tool chuck and loss of overlay registration.
Double peening – It is a two-stage surface treatment designed to improve a metal component’s lifespan and fatigue resistance. It involves performing a primary peening operation followed by a secondary peening operation using smaller, frequently harder, media at a lower intensity.
Double pendulum – It is a mechanical system formed by attaching one pendulum to the end of another. It is a classic physical model governed by coupled, non-linear differential equations where the motion of each arm influences the other, creating highly complex and frequently chaotic behaviour.
Double piston effect – It is the sealing principle of ball valves whereby line pressure is used
on both the upstream and downstream floating seats to cause a dead-tight seal simultaneously on both sides of the ball. With the double piston effect seat configuration when the upstream seat leaks, the
pressure entering into the body cavity acts on the downstream seat, which being of the PPE design is then pushed against the ball and the valve seals in both directions.
Double pitch roller chain – It consists of a roller chain type with longer pitch links, necessitating regular lubrication and inspections for wear in conveyor applications.
Double-pour casting – It is a specialized metalworking and manufacturing technique in which molten metal is poured into a mold in two distinct stages. This process allows engineers to create composite parts, typically cylindrical rollers, featuring a hard, wear-resistant outer shell surrounding a softer, highly durable, and shock-absorbing core.
Double pouring – It refers to a specialized casting technique where a mould is filled sequentially with two different molten alloys to create a bimetallic or composite component. The first metal forms a hard, wear-resistant outer shell, while the second metal fills the core to provide superior toughness and strength. The process normally involves two distinct methods namely static or centrifugal layering, and flow welding (burning-on).
Double pour roll – These are also called composite or duplex rolls. In order to get both high resistances to wear and high strength, roll makers have developed a roll making technology wherein the outer shell is made hard and the inner core tough by double pouring of metal of different compositions. The shell composition is maintained to give very high wear resistance properties and the core composition to give more strength. These are very costly type of rolls.
Double-press, double-sinter – It is a powder metallurgy technique where a metal part is compacted, partially sintered, and then compacted and sintered a second time. This sequential process breaks down internal voids and drastically increases the final part’s density, strength, and structural integrity.
Doubler – It is the localized areas of extra layers of reinforcement, normally to provide stiffness or strength for fastening or other abrupt load transfer.
Double ramp – It typically refers to a two-stage inclined geometry, such as a dual-wedge surface used in aerospace / fluid dynamics or a dual-acting mechanical ball-ramp mechanism, designed to manage sequential shock waves, double the axial travel, or provide symmetrical load distribution.
Double-reduced cold rolled sheet – It is a thin, high-strength steel sheet. It is manufactured by subjecting a standard, low-carbon cold-rolled coil to an additional cold reduction process (thickness reduction) after it has already been annealed.
Double reduced tin free steel – It is a high-strength, thin-gauge packaging material. It is made by cold-rolling mild steel, annealing it, and then cold-reducing it a second time before coating it with a thin layer of chromium and chromium oxide. This process makes the steel considerably harder and stronger than single-reduced varieties.
Double reduced tinplate – It is a highly specialized, thin, and remarkably strong type of steel sheet coated with tin. Unlike standard tinplate, it is cold-rolled twice. This extra processing step dramatically increases its hardness and yield strength, allowing manufacturers to use considerably thinner gauges while retaining excellent structural durability for cans and packaging.
Double-reduction die – It is a specialized tooling setup mainly utilized to either extrude multi-layer materials (like bi-metallic rods) or to compact metallic powders. The term specifically describes a system where the work-piece experiences two successive, distinct stages of mechanical deformation or compaction to achieve uniform properties.
Double reduction mill – It is a specialized metal rolling facility which reduces the thickness of annealed metal strip through a second cold rolling pass. Typically configuring 2 stands to 3 stands, it mainly produces extra-thin, high-strength materials, such as double-reduced (DR) tinplate used in can manufacturing.
Double-row roller conveyor – This design is used to convey wide and heavy loads. In place of one long and proportionately large diameter roller, two smaller diameter rollers with lengths less than half of the larger roller are used. For the support the inner ends of the pair of rollers, additional support frame is used. This design has lower cost than the same width conventional single row conveyor with longer and larger rollers.
Double salt – It is a salt which is composed of more than one different cation or anion, or which upon hydrolysis forms two different cations and anions. It is also a salt which is a molecular combination of two other salts.
Double shear notch – It is an abrupt deviation from straight on a sheared edge. This offset can occur if the flat sheet or plate product is longer than the blade for the final shearing operation.
Double-shear test – It is a shear test having two stationary, shear blades and one moving one and which uses solid round bars as test samples.
Double side-band – It refers to a type of amplitude modulation (AM) where a message signal modulates a carrier frequency, producing two symmetrical frequency bands (the upper and lower side-bands). In double side-band (DSB), unlike single side-band (SSB) transmissions, both side-bands are transmitted, but the unnecessary central carrier wave is often suppressed to save power.
Double-sided adhesive – It is a specialized bonding system comprising a central carrier layer coated with pressure-sensitive adhesive on both outer faces. It joins two substrates invisibly and distributes stress loads across the entire joint area without mechanical fasteners.
Double skin – It is also called double-skin penetration. It is a specific surface defect which occurs when molten metal penetrates the porous spaces of a sand mould or core, forming a fused secondary layer of metal and sand.
Double-skin façade – It is an advanced building envelope system made of two distinct glass layers separated by an intermediate air cavity. The cavity houses ventilation paths and shading devices to optimize thermal performance, sound insulation, and energy efficiency.
Double square groove weld – It is a type of groove weld.
Double-stage piston compressor – It compresses air twice, achieving higher pressures than single-stage compressors. It uses two cylinders or chambers with a piston in each to compress the air in two stages. The first stage compresses the air to a lower pressure, then it is cooled and compressed further in the second stage.
Double stimulus continuous quality scale – It is a standardized subjective testing method used in video and image engineering. Viewers watch an unimpaired reference clip and an impaired test clip in a random order. They grade the overall quality of both stimuli on a continuous vertical scale.
Double stimulus impairment scale – It is a standardized subjective testing method used to evaluate video or image quality by comparing an impaired test sample directly against an original reference.
Double strap joint – It is also called a double cover butt joint. It is a mechanical or adhesive connection. Two main structural plates lie end-to-end in the same plane, and two extra plates called straps or cover plates are placed symmetrically on both sides, one on top and one on the bottom, to bridge and reinforce the connection.
Double-stroke heading machine – It is a high-speed cold-forming or forging machine which uses a single die and two consecutive punches (blows) to shape a metal blank. It is mainly used to manufacture industrial fasteners like bolts, screws, and rivets.
Double-stroke open-die heading machine – It is a specialized metal forging machine which uses a single open die paired with two successive punches (or blows) to form elongated metal parts. It cuts wire or rod to length and shapes the material without adding heat.
Double stroke solid die cold heading machines – These machines are available in the same sizes as single stroke solid die heading machines. These machines can make short-to-medium length products (normally 8 to 16 diameters long), and they can make heads which are as large as three times the diameter of the work piece. These machines can be equipped for relief heading, which is a process for filling out sharp corners on the shoulder of a work piece, or a square under the head. Some extruding can also be done in these machines. Because of their versatility over single stroke cold heading machines, double stroke solid die heading machines are extensively used in the production of fasteners.
Double stroke open die heading machines – These machines are made in a wider range of sizes than single stroke open die heading machines and can produce heads as large as three times the diameter of the work piece. These machines cannot be used for extrusion, but these can pinch fins on the work piece, when needed. These machines normally pinch fins or small lines under the head of the work piece when these are not required. If these fins or lines are objectionable, these are to be removed by another operation.
Double submerged arc welded steel pipe – It refers to the steel pipe manufactured by the double sub-merged arc welding technology. Double submerged arc welded (DSAW) can be straight seam steel pipe or spiral steel pipe.
Double sub-merged arc welding – It is an advanced industrial technique used to create high-strength, robust welded joints, normally for thick-walled, large-diameter pipes. It involves simultaneous welding on the inner and outer surfaces of a joint using two welding heads, where the electric arc is completely buried under a layer of granular flux.
Double-taper die – It is a specialized compression mould featuring a bore which gradually widens at both the top and bottom openings. This design relieves internal stress and reduces friction during the ejection of pressed parts, preventing defects like cracking and delamination.
Doublet distribution – It is an array or continuous spread of elemental flow singularities (doublets) along a line, surface, or boundary to model complex potential flow fields and pressure distributions.
Double tempering – It is a heat treatment process in which a quench-hardened ferrous metal is subjected to two complete tempering cycles, normally at substantially the same temperature, for the purpose of ensuring completion of the tempering reaction and promoting stability of the resulting micro-structure. This sequential cycling relieves internal stress, and improves toughness and ductility without excessively sacrificing the metal’s hardness.
Double U-groove weld – It is a joint preparation used in fabrication for thick metals (typically over 20 millimeters). Both joining plates are machined on both sides to form a symmetrical U-shape. This needs welding from both sides to achieve full joint penetration while minimizing filler material and material distortion.
Double upsetting and piercing – It refers to a sequential industrial forging process where a metal bar or billet is compressed to increase its thickness (upsetting) and subsequently punched or pushed through twice to form a hollow, expanded-diameter component (such as heavy-duty nuts or flanged sockets). Double upsetting and piercing can frequently be used to produce complicated shapes, such as the cluster gear.
Double vacuum-induction melting – It is a specialized metallurgical process where raw metals are melted and solidified twice using electro-magnetic induction inside a high-vacuum chamber. This secondary cycle aggressively strips volatile impurities and dissolved gases, yielding ultra-pure super-alloys and specialty steels needed for demanding nuclear applications.
Double V-groove weld – It is a joint preparation used in heavy structural fabrication. It involves beveling both edges of two joining plates from both sides, creating a symmetrical, hourglass-shaped cross-section. This method is chosen to achieve deep penetration in thick metals while minimizing warping and filler requirements.
Double wall brazed tubes – These are specialty tubes which are confined to small sizes. They are used in large quantities by the automotive industry for brake lines and fuel lines, and by the refrigeration industry for refrigerant lines. They are made by forming copper coated strip into a tubular section with double walls, using either single strip or double strip construction. The tubes are then heated in a reducing atmosphere to join all mating surfaces completely. The resulting products are hence copper coated both inside and outside. When needed by the intended service, a tin coated tubes can also be produced. Available sizes range from 3 millimeters to 15 millimeters in outside diameters with wall thickness from 0.65 millimeters for 3 millimeters outside diameters to 0.9 millimeters for 15 millimeters outside diameters. These tubes are usually made to very small sizes for use with standard compression fittings. It can be sink drawn for the improvement of surface finish and tolerances.
Double-walled carbon nano-tube – It is a nano-scale cylinder made of two concentric graphene sheets nested one inside the other. It bridges the gap between single-walled and multi-walled tubes, offering high mechanical strength, chemical resistance, and stable electrical properties.
Double-welded joint – In arc and oxy-fuel gas welding, it is a fusion welded joint which is welded from both sides.
Double wrap basket hitch – It is a basket hitch wrapped completely around the load and compressing it rather than merely supporting it, as it is done in the ordinary basket hitch. The double wrap basket hitch can be used in pairs like the double basket hitch. This method is excellent for handling loose material, pipe, rod or smooth cylindrical loads because the sling is in full 360-degree contact with the load and tends to draw it together. On smooth surfaces, this type of hitch is a better choice.
Double wrap choker hitch – It is formed by wrapping the sling completely around the load and hooking it into the vertical part of the sling. This hitch is in full 360 degrees contact with the load and tends to draw it tightly together. It can be used either singly on short, easily balanced loads or in pairs on longer loads. The loosely-bundled loads are usually lifted with this hitch.
Doubling bifurcation – It is also called a period-doubling bifurcation or flip bifurcation. It is a non-linear systems phenomenon where an engineering system changes its steady or periodic behaviour. As a control parameter shifts, the original oscillation period (T) loses stability and splits into a new stable motion that takes twice as long (2T) to repeat.
Doubly connected duct – It refers to an annular cross-section flow passage formed by two concentric or eccentric boundaries (such as an inner and outer cylinder), meaning its cross-sectional area has one interior boundary hole, creating two distinct boundary wall surfaces for fluid flow and heat transfer analysis.
Doubly fed induction machine – It is a wound rotor induction generator which features a rotor circuit fed by a pair of partially rated power converters, allowing for bi-directional power flow and speed variation. It operates with the stator winding connected directly to the grid and can deliver power at both super-synchronous and sub-synchronous speeds.
Doubly-fed induction generator – It is an asynchronous AC (alternating current) electrical generator with a wound rotor where both the stator and the rotor are connected to external electrical power paths. The stator connects directly to the grid, while the rotor connects through a bi-directional power electronic converter, enabling variable-speed operation and independent control of active and reactive power.
Doughnut rollers – These are circular rollers with a central opening supporting and guiding the conveyor belt, needing periodic checks for wear and alignment.
Dowel – It is a wooden or metal pin of different types used in the parting surface of parted patterns and core boxes. In die casting dies, it is the metal pins for ensuring correct registry of cover and ejector halves.
Dowel action – It is the mechanism where internal reinforcing steel bars (reinforcement bar) or dedicated dowel pins resist and transfer shear forces perpendicular to their longitudinal axis when a concrete member undergoes transverse displacement or cracks.
Dowel key – It is also called a dowel pin or cylindrical key. It is a precision-machined, headless pin or cylindrical rod used to securely lock two parts together, ensuring exact alignment and transmitting torque. Unlike screws, they do not carry clamping loads, relying entirely on a tight, precision fit to absorb shear forces.
Dowel pin – It is a pin fitted onto the body of quarter turn valves. This pin aligns the adapter plate and restrains the plate and gear operator from moving while the valve is being operated.
Dowel pocket – It is a precision recess machined directly into heavy industrial dies (such as forging or die-casting equipment). It accommodates a dowel key to perfectly align the upper and lower die halves, preventing lateral shifting under extreme pressure.
Down-comer – It is a vertical pipe, duct, or channel used to conduct fluids, gases, or materials downward by gravity or pressure. The exact design and function vary, but its main purpose is always to safely and efficiently transport a substance from an upper level to a lower level. In blast furnace, it is the pipe which carries blast furnace gas from uptake to the dust catcher.
Down-cut milling – It is also known as climb milling. It is a machining process where the milling cutter rotates in the exact same direction as the work-piece feed. As the cutter engages the metal, the chip thickness starts at its maximum and decreases to zero at the end of the cut. This cutting mechanism produces unique mechanical properties and performance benefits.
Down-draft – It is an unwanted or designed downward movement of gas or air inside a system like a chimney, ventilation network, furnace, or gasifier. It can cause smoke backup in buildings or direct fuel and gases downward in thermal conversion units.
Downdraft gasifier – It is a co-current fixed-bed reactor where both the solid biomass fuel and the gasifying air move downward together. As volatile tars and gases pass through a hot oxidation zone, they thermally crack into a clean, low-tar syngas ideal for direct engine power generation.
Downer reactor – It is a co-current downward transport reactor used in chemical processing. In downer reactor, the gas and solids flow downward co-currently. It has unique features such as shorter residence time, narrow residence time distribution, approximate plug flow mode and relatively slight cluster structure compared with riser reactors. These unique features make it suitable as the coal / biomass pyrolizer since the pyrolysis reaction belongs to the ultra-fast reaction with the intermediates as the target product.
Down-flow operation – It means a process where fluids (liquids or gases) move downward through a system, vessel, or treatment unit, driven by gravity or mechanical pressure. This contrasts with up-flow systems where media moves upward.
Down-force – It is a downward vertical force generated by the aero-dynamics of a moving vehicle. It acts as negative lift, pressing a car into the road surface to increase tyre grip without adding dead weight.
Down-gate – It is the mould channel which connects the pouring basin with the runner or, in the absence of a pouring basin, directly into which molten metal is poured. Sometimes it is referred to as sprue or down-sprue. It is also sometimes used to mean all gates, risers, runners, and similar scrap which are removed from castings after shakeout.
Down-gradient – It is a position down along a gradient from a starting position. In hydrology, down-gradient is allocation which receives ground-water from another location. It is similar to down-stream.
Down-gradient diffusion – It is a random molecular process where there is net movement of variables such as chemicals, temperature, moisture, or momentum, from regions of high concentration toward lower concentration.
Downgrading – It refers to the process of officially reducing a component, material, or system to a lower capacity, specification, or classification. This is done to safely accommodate degradation, extend the lifespan of aging assets, or adjust for revised operational requirements.
Down-hand welding – It is welding from the upper side of the joint, the face of the weld being horizontal. It is also known as flat-position welding.
Downhole condition – It refers to the physical, mechanical, and chemical environment existing inside a drilled well-bore. This includes extreme downhole metrics like high pressure, high temperature, mechanical stress, and corrosive fluid presence which tools and tubular structures are to endure.
Downhole data – It is the process of collecting, transmitting, and analyzing physical measurements taken inside a well-bore. It uses sub-surface sensors to track downhole conditions like pressure, temperature, and vibration, helping to optimize drilling performance, ensure well safety, and evaluate underground reservoirs
Downhole deployment valve – It is a specialized, surface-controlled full-bore isolation valve integrated into a well’s casing string. It safely isolates high-pressure reservoir formations below so operators can bleed off pressure above. This eliminates the need for expensive snubbing units or well-killing procedures during under-balanced or managed pressure drilling.
Downhole fire – It is an underground detonation or high-intensity reaction which occurs inside a well-bore, typically within the drill string or annulus, when hydro-carbon influxes mix with an oxygen-rich drilling fluid like compressed air. It acts as a rapid explosion rather than a steady flame.
Downhole motor – It is also called mud motor. It is a positive-displacement hydraulic tool which utilizes the relative motion of a rotor and stator, with lobes designed to maintain contact while rotating with respect to each other. It is placed at the bottom of a drill string. It converts the pressure and flow of pumped drilling fluid into mechanical rotational energy to spin the drill bit independently of the outer drill pipe.
Downhole temperature – It is the thermal measurement inside a well-bore or surrounding sub-surface formation at a specific depth. It is driven by the local geothermal gradient and modified dynamically by heat transfer from drilling fluids, production streams, or injection processes.
Downhole tools – These are specialized devices run inside a well-bore below the well-head. They execute drilling, formation evaluation, well completion, and intervention tasks under extreme conditions of high temperature, high pressure, and corrosive fluids. Downhole tools are composed of downhole components, tool systems, and isolation barrier valves.
Downlink and uplink transmission – It refers to the communication channels in cellular networks where downlink is the transmission from base stations to mobile users, and uplink is from mobile users back to base stations. These channels experience different degradations such as path loss, shadowing, and small-scale fading, affecting their performance.
Downlink carrier – It is a specific radio frequency channel which transmits data, signals, or power from a central base station down to a local user device, mobile phone, or ground receiver.
Downlink case – It refers to the transmission scenario in which data is sent from a base station to a mobile device, typically involving interference considerations which differ from those in uplink transmissions. Downlink case refers to a specific transmission scenario where data, control signals, or power flow downward from a central base station, access point, or satellite to a receiver, user equipment, or mobile device.
Downlink cell band-width – It is the total range of radio frequencies assigned to a base station for transmitting signals down to user devices. It sets the physical capacity for data and control channels across that specific cell sector.
Downlink data – It is the information sent from a central source, like a base station, satellite, or network node, down to a local receiver, mobile device, or ground station. It handles tasks like video streaming, web browsing, and system control commands.
Downlink multi-antenna precoding – It refers to the technique of using multiple antennas at the transmitter to optimize the transmission of signals to multiple users in a wireless communication system, leveraging channel state information (CSI) for improved performance.
Downlink path – It is the transmission channel for signals, data, and control information moving from a central source, such as a base station, satellite, or drilling surface control, down to a receiver like a mobile device, earth station, or downhole tool.
Downlink resource – It is the process of mapping time, frequency, and antenna power from a base station to user devices. It uses a physical grid where small pieces called resource elements carry control messages, reference signals, and user data.
Downlink scheduling assignment – It is a set of radio resource blocks and transport formats given by a base station to a mobile device. It tells the device where and how to receive data sent from the network in the same transmission time interval.
Downlink sub-frame – It is a 1-milli-second time interval in wireless telecommunications, where a base station sends data and control signals to a user device.
Downlink traffic – It is the flow of data moving from a central network source, such as a base station, satellite, or core network, down to an end-user device like a smartphone, computer, or ground station.
Downlink transmission – It is the process of sending data, signals, or power from a central network source, such as a base station, satellite, or access point, down to a local receiver or end-user device like a smartphone or ground terminal.
Down milling – It is the milling in which the cutter moves in the direction of feed at the point of contact.
Downscaling – It refers to the technique of taking large-scale, coarse-resolution models or datasets and translating them into high-resolution, localized, or fine-scale information. It is heavily used in environmental, civil, and software engineering to predict local impacts from massive datasets. It is a procedure to infer high-resolution information from low-resolution variables. This technique is based on dynamical or statistical approaches normally used in several disciplines, especially meteorology, climatology, and remote sensing. The term ‘downscaling’ normally refers to an increase in spatial resolution, but it is frequently also used for temporal resolution. This is not to be confused with image downscaling which is a process of reducing an image from a higher resolution to a lower resolution.
Down-speeding – Down-speeding of an engine is a powertrain engineering strategy which reduces the engine’s operating revolutions per minute (rpm) at normal cruising speeds while maintaining vehicle road speed and power. This is achieved using faster (numerically lower) rear axle ratios paired with specially tuned transmissions and high-torque engines to lower fuel consumption and mechanical wear.
Down sprue – It is the mould channel which connects the pouring basin with the runner or, in the absence of a pouring basin, directly into which molten metal is poured. Sometimes it is referred to as sprue or down-gate. It is also sometimes used to mean all gates, risers, runners, and similar scrap which are removed from castings after shakeout.
Downstream cylinder – It is a circular structure or pillar positioned second in the path of fluid or wave flow, directly behind another (upstream) cylinder. It experiences altered hydrodynamic forces, wake impacts, and vortex shedding created by the first object.
Downstream direction – It means moving in the direction of the flow, data transfer, or sequential steps of a process. It represents anything which happens later in time, position, or transmission relative to a starting point.
Downstream distance – It is the physical length or space measured along the direction of a fluid current (like a river), or the length of a path moving away from a source in a network, calculated mathematically using the combined speed of motion and current.
Downstream face – It is the outer, air-exposed side of a dam wall or embankment which faces away from the stored reservoir and toward the direction of the outflowing river. It plays a key role in structural stability, drainage, and weathering resistance.
Downstream location – It refers to any point, equipment, process, or component which is situated later in the direction of flow, progression, or sequence relative to a designated reference point.
Downstream operation – It refers to any subsequent processing, purification, refining, or distribution step which occurs after the initial production, extraction, or synthesis of a product. It converts raw or intermediate outputs into final, usable goods for end-users.
Downstream pressure – It is the static or dynamic fluid pressure measured on the outlet or discharge side of a component (such as a valve, pump, orifice, or filter) in the direction of the fluid flow.
Downstream processing – It refers to the extraction, purification, and concentration of a target product from a raw material source. It refers to the subsequent stages of refining, purifying, and converting crude metal concentrates or semi-finished materials into high-purity metals, alloys, or finished industrial shapes ready for manufacturing. It denotes value-addition steps occurring after initial extraction.
Downstream project – It is the phase where high-level concepts for post-production, refining, or processing facilities are turned into clear technical plans. It sets the project scope, cost estimates, and schedules before building begins.
Downstream section – It refers to a component, process, fluid path, or data sequence which occurs later in a system’s flow or production line relative to a defined reference point. It receives the output, material, or signal produced by an earlier (upstream) section.
Downstream slope – It is the inclined outer surface of an embankment, dam, or retaining structure which faces away from the main body of water or highest elevation. It carries water runoff away from the crest and is heavily prone to erosion, requiring stabilization.
Downstream water level – It is the elevation of the free water surface in a channel, river, or piping system on the exit or discharge side of a hydraulic structure (such as a dam, spillway, weir, or gate). Also known as the tailwater level, it dictates the effective hydraulic head and discharge capacity.
Downstroke – It is the downward movement of a piston, plunger, or machine component within a cylinder or reciprocating assembly. It typically constitutes the power-delivering or fluid-displacing phase of a mechanical cycle.
Down-time – it is a period when equipment, systems, or production lines are non-operational or idle. It represents a direct loss in productivity and is categorized into planned (scheduled maintenance, change-overs) and unplanned (break-downs, failures) occurrences.
Downward bending – It describes the structural deflection or curvature of a horizontal member (like a beam or plate) curving toward the ground under a transverse load, creating a ‘sagging’ condition where the top fibres experience compression and the bottom fibres experience tension.
Downward direction – It refers to vector orientation aligned with the local force of gravity (towards the centre of the earth), typically represented as the negative z-axis (Z) in Cartesian coordinate systems.
Downward flow – it means the movement of a fluid, gas, or material from top to bottom because of the gravity or applied pressure. It is used in systems like water filters, chemical reactors, and vertical mixers to guide motion, mix particles, or separate materials.
Downwash – It is the downward deflection of a fluid (such as air or gas) caused by an aerodynamic body like a rotor blade, or building structure. It plays a vital role in generating lift, and creating induced drag.
Downwash angle – It is the angle by which airflow is deflected downward. It is the angular difference between the undisturbed free-stream velocity vector and the deflected local airflow vector.
Dow process – It is a process for the production of magnesium by electrolysis of molten magnesium chloride.
DQ control – It means direct-quadrature control, or vector current control. It is a technique used to simplify the regulation of three-phase AC (alternating current) electrical systems. By transforming time-varying sinusoidal alternating current (AC) quantities into constant DC (direct current) values through a rotating reference frame, it allows engineers to use standard direct current (DC) controllers.
DR7.5 temper grade – It has aimed hardness value of 71 (Rockwell 30T scale value). It is used in the applications needing stiffness and strength such as production of large bodies for beer cans, carbonated beverage cans, and DRD (drawn and re-drawn) cans etc.
DR8 temper grade – It has aimed hardness value of 72 (Rockwell 30T scale value). It is used in the applications needing stiffness and strength such as in the production of large bodies for beer cans, carbonated beverage cans, and DRD (drawn and re-drawn) cans etc.
DR8.5 temper grade – It has aimed hardness value of 73 (Rockwell 30T scale value). It is used in the applications needing stiffness and strength such as in the production of large bodies for beer cans, carbonated beverage cans, and DRD(drawn and re-drawn) cans etc.
DR9 temper grade – It has aimed hardness value of 75 (Rockwell 30T scale value). It is used in the applications needing stiffness and strength such as in the production of tops and bottoms for beer cans, and carbonated beverage cans, and bodies DRD (drawn and re-drawn) cans etc.
DR9M temper grade – It has aimed hardness value of 76 (Rockwell 30T scale value). It has similar application as DR 9 temper grade.
DR10 temper grade – It has a hardness value of 79 (Rockwell 30T scale value). It is used in special application which needs strength such as in the production of tops and bottoms for beer cans, and carbonated beverage cans, and bodies DRD (drawn and re-drawn) cans etc.
Draft – It is an angle or taper on the surface of a pattern, core box, punch, or die (or of the parts made with them) which facilitates removal of the parts from a mould or die cavity, or a core from a casting. It is also the change in cross section which occurs during rolling or cold drawing.
Draft aft – It is the vertical distance measured from the water-line to the bottom of the hull at the stern (the rear) of a ship. It changes based on weight distribution, cargo loading, and ballast.
Draft allowance – It is an intentional slight taper or angle added to the vertical surfaces of a pattern or mould in manufacturing (like metal casting or injection moulding). It prevents the mould cavity from breaking by ensuring the pattern can be removed smoothly and without friction.
Draft angle – It is the angle of taper, normally 5-degree to 7-degree given to the sides of a forging and the sidewalls of the die impression.
Draft free – It is also called no-draft, or draft-less. It is normally used to describe a closed-die forging with
a specified draft angle of 0-degree. Some latitude is permitted in the tolerances (e.g., + 1/2-degree) which accompany this requirement. A principal objective of the draft-free process is to eliminate machining on specified surfaces of the forging, hence eliminating cut grain and improving stress-corrosion resistance. The process is restricted to the forging of aluminum alloys and has found its widest use in aerospace applications in which anticipated production of a given forging frequently is only a few hundred pieces and, hence, die wear for the run is negligible. In the absence of draft, mechanical ejection is normally used to remove these forgings from the dies. The forgings are normally designed with knockout pads to provide protection at knock-out pin locations. In filling a die cavity, such as that
for a vertical rib, resistance to metal flow is normally at a minimum when the cavity has parallel walls, i.e., zero draft.
Draft gasifier – It is also spelled draught gasifier. It is a thermo-chemical reactor which converts carbonaceous solid fuels (like bio-mass or coal) into a combustible gas mixture known as producer gas or syngas. The term ‘draft” specifies how air or oxygen movement is managed inside the system, which can be natural draft (driven by thermal buoyancy and pressure differences) or forced draft (driven by external fans or blowers).
Drafting – It is the act and discipline of composing drawings which visually communicate how something functions or is constructed. It refers to the creation of precise, detailed technical drawings, frequently used for engineering or architectural purposes. It is a more structured and standardized process compared to freehand sketching or artistic drawing, aiming to communicate specific design details and instructions for manufacturing or construction.
Drafting roller – It is a component in a spinning or drawing machine which uses pairs of rotating metal and synthetic-coated cylinders running at different speeds to stretch, align, and thin out bundles of raw fibres.
Drafting zone – It is the precise space between pairs of rotating rollers where a fibre strand (like a sliver, roving, or yarn) is stretched, made thinner, and made more parallel by setting each successive roller pair to run faster than the previous one.
Draft international standard – It is a proposed global standard which has passed the initial technical committee phase but is still undergoing formal review. It is circulated among global member bodies for voting and feedback before being approved as an official international standard.
Draft, pattern – Pattern draft or pattern taper is a slight angle added to the vertical surfaces of a pattern. It is an important allowance designed to facilitate the smooth, easy withdrawal of the pattern from the sand mould without damaging or tearing the mould cavity.
Draft ratio – It is also called draw ratio. It is the main numerical index used to measure the severity of a drawing operation. It is calculated by dividing the initial blank diameter (D0) by the final cup or punch diameter (D1), expressed as ‘DR = D0/D1’.
Draftsman – Draftsman is also spelled a draughtsman. A draftsman is a skilled person who creates technical drawings and plans, typically for machinery, buildings, or other structures. Draftsmen use drafting tools and software (like computer aided design) to produce detailed and accurate visual representations which are used in engineering and several industries.
Draftsperson – It is a technical professional who turns rough sketches, notes, and concepts from engineers into precise, scaled blue-prints and technical drawings. They use computer software to map out exact measurements, materials, and guidelines for building parts or structures.
Draft tolerances – These refer to the permissible variation in the specific taper (draft angle) added to cast, forged, or moulded metal parts. It dictates how much a metal feature can deviate from its nominal draft angle while still allowing the part to be cleanly removed from the mould.
Draft tube – It is an expanding pipe which connects a reaction water turbine’s runner exit to the tail-race. It slows down the exiting water. This turns wasted speed into useful pressure. It also lets workers place the turbine safely above the water level.
Drag – It is the bottom section of a flask, mould, or pattern. In thermal cutting, it is the offset distance between the actual and the theoretical exit points of the cutting oxygen stream measured on the exit surface of the material.
Drag, flight kinematics – In flight kinematics and aerodynamics, drag is the mechanical force which acts parallel and opposite to an object’s direction of motion relative to the surrounding air. It resists movement, drains energy, and is to be continuously counter-acted by engine thrust for an object to maintain steady flight.
Drag chain – It also called a cable carrier or energy chain. It is a flexible, hollow channel made of linked plastic or metal pieces. It holds and protects electrical wires and fluid hoses as they move back and forth on automated machines.
Drag chain conveyor – It is a conveyor having one or more endless chains, which slides in a track or tracks, resting at the bottom of a trough, and materials resting directly on the chain are carried by the chain links. The layers of materials above the chain level are moved by the cohesiveness with the material below. The troughs or sliding base surface can be made of steel, concrete or even wood. The chain tracks are frequently made from steel channels. These conveyors normally work in the same horizontal plane with little inclines, for movement of bulk materials, hot materials, abrasive materials, logs / timber, and packages etc. Even cars can be moved in a car assembly line by putting two wheels on one chain.
Drag chain feeders – These feeders are also called drag flight feeders. Drag chain feeders extract the material from the storage unit. They are suitable for materials of moderate size lumps and of average abrasiveness. The storage unit outlet can have some length along feeder. It can provide enclosed construction. The feeder needs minimum installation heights. It also imparts agitation to the bulk material at the outlet i.e.it improves flow at the hopper outlet. Typical capacity range of drag chain / drag flight feeders is up to 100 cubic meter per hour.
Drag coefficient – It is a dimensionless quantity which quantifies the resistance an object experiences as it moves through a fluid (like air or water). It is a measure of how effectively an object ‘cuts through’ the fluid. A lower drag coefficient indicates less resistance and a more streamlined shape, while a higher coefficient indicates more resistance and a less streamlined shape.
Drag crisis – It is a sudden, sharp drop in an object’s drag coefficient which happens as the Reynolds number increases. It occurs when the fluid boundary layer around a bluff body shifts from laminar to turbulent, delaying flow separation and shrinking the wake behind the object.
Drag direction – It is a vector aligned parallel to the oncoming fluid flow stream relative to an object, pointing directly opposite to the relative motion of the solid body moving through the fluid.
Drag divergence – It is the point where an aircraft’s drag coefficient starts to rise fast. This sharp increase happens as the drag-divergence Mach number is reached. It is caused by shock waves forming on the wings.
Drag flow – It is the movement of a fluid caused by the direct mechanical dragging of a moving boundary or surface, such as a rotating wall or a moving plate, pulling adjacent fluid particles along through viscous friction.
Drag fold – The result of the plastic deformation of a rock unit where it has been folded or bent back on itself.
Drag force – It is the resistance force caused by the motion of a body through a fluid, such as water or air. A drag force acts opposite to the direction of the oncoming flow velocity. The first point of view for the cause of drag is the skin friction.
Drag force coefficient – It is a dimensionless number which quantifies the drag force experienced by a particle relative to the dynamic conditions of the surrounding fluid, and it is influenced by the particle’s shape and Reynolds number. It is important for calculating the settling speed of particles in fluid dynamics.
Drag fold – The result of the plastic deformation of a rock unit where it has been folded or bent back on itself.
Drag-in – It is the water or solution which adheres to the objects introduced into a bath.
Drag load – It is a force which pushes on an object or structure in the direction of fluid flow (like air or water), or a downward friction force pulling on a deep foundation pile when surrounding soil settles. In case of fluid dynamics and aerodynamics, it is the resistive force exerted on a solid body when a fluid moves past it, or when the body moves through a fluid. In case of geo-technical and structural engineering, it is an extra downward pulling force (negative skin friction) applied to a deep foundation pile.
Drag mark – It is a surface area showing a scratch or abrasion resulting from contact of the hot extrusion with the press equipment or tooling or, in the case of multi-hole dies, with other sections as they exit the press.
Drag-out – It is the solution which adheres to the objects removed from a bath.
Drag-over mill – It is also called a pull-over mill. It is a simple, two-high, non-reversing rolling mill where the rolls spin in only one direction. It refers to a machine where the metal is passed between the rollers, then manually lifted and carried back over the top of the mill to be fed through the same gap for another pass.
Drag ratio – It typically refers to the lift-to-drag ratio (L/D ratio), which measures how well an object generates lift compared to the retarding force of drag. It is a key indicator of aerodynamic efficiency.
Drag reducer – It normally known as a drag reducing agent (DRA) or flow improver. It is an ultra-high-molecular-weight polymer additive mixed into liquids inside pipe-lines to decrease turbulent friction, lower pumping pressure, and boost fluid throughput capacity.
Drag reducing agent – It is also called flow-improver. It is an ultra-high-molecular-weight polymer injected in parts-per-million (ppm) concentrations into a liquid pipeline to suppress turbulent flow and reduce frictional pressure loss. This allows operators to increase fluid throughput or lower pumping energy requirements.
Drag reduction – It is the method or physical process of lowering the aerodynamic or hydrodynamic resistance force acting on an object moving through a fluid, or decreasing the frictional pressure drop of a fluid flowing through a pipe.
Drag stress – It is an internal resisting stress caused by the movement and interaction of dislocations within a crystal lattice, which increases with higher strain rates. In fluid mechanics, it relates to the shear and pressure stresses exerted by a fluid moving past a solid surface.
Drain – It is a conduit, channel, or other structure constructed or used to carry waste liquid discharges by gravity or pumping.
Drainage – It is the act, process, or mode of becoming emptied or freed of cleaning solutions and / or zinc. Fabricated items immersed in molten zinc are to be designed and to allow the zinc to freely drain from internal and external surfaces are to be suspended correctly during the galvanizing process.
Drainage area – It is also called a catchment area, watershed, or drainage basin. It is the total land surface horizontal plane where rain and surface runoff flow down to a single shared point, like a pipe inlet, stream, or outfall.
Drainage coefficient – It is the design capacity of a drainage system, defined as the specific depth of water (surplus water or run-off) which the system is required to remove from a given drainage area in a 24-hour period.
Drainage function – It is the controlled natural or artificial removal of excess surface and subsurface water from a system, land area, or structure. Its main purpose is to prevent flooding, stabilize soil integrity, and protect structural foundations from water-induced damage.
Drainage layer – It is a highly permeable, horizontal structural stratum made of coarse granular aggregates or geo-synthetics. It collects and rapidly conveys percolating water or subsurface moisture away from critical infrastructure like pavements, retaining walls, and landfills, while acting as a capillary break.
Drainage radius – It is the effective distance from a well to the outer boundary of a reservoir from which fluid can be effectively drained, frequently represented in terms of pressure or pseudo-pressure in steady-state flow conditions.
Drainage rate – It is the speed at which a system removes excess water or liquid. It is measured as a volume or mass per unit of time. Engineers use this value to design safe and effective pipes, soils, and filters.
Drainage structure – It is a built component or system designed to collect, convey, and discharge surface water or sub-surface ground-water safely away from infrastructure, preventing floods, soil erosion, and structural damage.
Drain bias – It is the direct current (DC) voltage applied to the drain terminal of a field-effect transistor (FET). This voltage sets the baseline operating point, or quiescent point, for the channel current and determines whether the device functions in the linear, ohmic, or saturation region.
Drain circuit – It normally refers to the terminal, connection, or sub-path tied to the drain electrode of a field-effect transistor (FET), or a circuit designed to safely remove (‘drain’) unwanted charges or currents.
Drain electrode – It is the terminal in a field-effect transistor (FET) where charge carriers (such as electrons or holes) leave the active channel. It collects the current driven through the semi-conductor material, and its voltage level relative to the source dictates the device’s operational state.
Drain end – It typically refers to the terminal outlet or discharge point of a fluid conduit, pipe network, or channel where liquid exits the system. It can also describe the physical terminal electrode of a field-effect transistor (FET) or the discharge termination of a cable shield’s drain wire.
Drain field – It is also called leach field. It is a sub-surface waste-water disposal component consisting of perforated pipes in gravel-filled trenches. It receives liquid effluent from a septic tank and uses natural soil filtration and microbial action for final purification and dispersal.
Drain hole – It is a deliberate opening placed at the lowest point of a structure, component, or enclosure to let trapped liquids or condensed moisture escape, preventing structural corrosion, electrical shorts, or unwanted internal pressure buildup.
Draining – It is part of the dipping or flow coating process during which the excess slip flows from suitably positioned ware.
Drain installation – It is the precise process of placing pipes, channels, or vertical drains to collect and move surface water, ground-water, or waste-water away from structures and land. The goal is to stop flooding, protect foundations, and stabilize soil.
Drain junction – It is a pipe fitting where two or more waste-water or storm-water lines meet. It is also the p-n boundary region connected to the drain terminal of a field-effect transistor (FET).
Drain opening – It is the designated physical inlet or aperture in a system, such as a drain pan, surface channel, or containment network, sized and positioned to clear liquid or surface runoff through gravity safely away from important structures or equipment. Depending on the specific branch of engineering, the term can refer to structural or electrical setups. In structure set-up, it is the precise entry point on a basin, trench, or roof pan designed to prevent fluid accumulation or localized flooding. In case of electrical set-up, it consists of an open-drain output pin on a device which uses an internal transistor to pull a signal line to ground, leaving the pin floating when turned off.
Drain output – Open-drain output is a circuit configuration where an output pin connects to the drain terminal of an internal MOSFET (metal-oxide semiconductor field-effect transistor). The transistor acts as a switch that pulls the pin down to ground (logic low) or leaves it floating in a high-impedance state (off). It needs an external pull-up resistor to supply a high voltage level.
Drain pipe – It is the primary vessel or conduit for unwanted water or waste liquids to flow away, either to a more useful area, funnelled into a receptacle, or run into sewers or stormwater mains as waste discharge to be released or processed. In majority of the systems, the drain pipe is for discharge of waste fluids.
Drain plug – It is a fitting at the bottom of a valve, the removal of which permits draining and flushing the body cavity. The vent plug assembly on some ball and gate valves also serves as a drain valve.
Drain points – In steam distribution systems, drain points are specific locations, typically the lowest points of a pipe-line or equipment, designed to safely collect and remove condensed water. These systems are necessary for maintaining system efficiency and preventing severe pipe damage.
Drain region – It refers to a catchment or drainage area which collects run-off. In semi-conductor engineering, it is the terminal in a MOSFET (metal-oxide semiconductor field-effect transistor) transistor where charge carriers leave the channel.
Drain separation – It very frequently refers to the gate-to-drain spacing in semi-conductor devices, like power transistors or HFETs (hetero-structure field effect transistors), which dictates breakdown voltage and electric field distribution. In a broader environmental or civil context, it can also refer to separated drainage systems that isolate sanitary sewage from stormwater run-off.
Drain spacing – It is the horizontal distance measured between adjacent parallel subsurface pipes, tiles, or vertical ground improvement drains. It is a critical design parameter used to control ground-water tables, prevent soil waterlogging, manage soil salinity, or accelerate consolidation in weak geo-technical soils.
Drain time – It is the time needed for porcelain enamel slip applied by dipping, slushing, or flow coating to complete movement across the surfaces of a coated part.
Drain voltage – It is the electrical potential at the drain terminal of a field-effect transistor (FET), such as a MOSFET (metal-oxide semiconductor field-effect transistor), relative to the source terminal. It drives the charge carriers through the channel and sets the device’s operating region.
Drape – It is the ability of a polymer sheet or composite sheet to conform to the shape of the mould.
Drape coefficient – It is a ratio measuring how a flexible material like fabric hangs and bends under its own weight. Expressed as a percentage, it equals the projected shadow area of a draped circular sample divided by its total unsupported flat area. Higher values indicate stiffer materials.
Drastic change – It is a severe, sudden, and fundamental alteration to a system, design, process, or project direction. It breaks away from standard limits or minor upgrades. It is used when normal adjustments fail and teams are to apply extreme measures to fix a major problem.
Draw – It is a term used to denote the shrinkage which appears on the surface of a casting. This term has been used formerly to describe tempering. It is also a term used to remove pattern from mould, and as an external contraction defect on surface of mould. Draw also means to remove a pattern from a mould.
Drawability – It is a measure of the formability of a sheet metal subject to a drawing process. The term is normally used for indicating the ability of a metal to be deep drawn. The drawability of a metal depends on two factors namely (i) the ability of the material in the flange region to flow easily in the plane of the sheet under shear, (ii) the ability of the side-wall material to resist deformation in the thickness direction.
Draw and iron-can bodies – It is the term which refers to a method of fabricating a can body in which a cup is drawn from flat sheet, redrawn to the final diameter, and then wall ironed to reduce the wall thickness and to achieve the needed height.
Draw and wipe process – It refers to a specialized technique used in wire manufacturing where continuous wire or rod is drawn (pulled) through a die to reduce its diameter, followed immediately by passing through a mechanical wiping device to remove excess lubricant or apply a uniform thin coating.
Draw-back – It is a removable section of a sand mould. It is typically lifted away on a plate or arbour to allow the safe removal of a pattern without damaging the mould cavity, and then slid back into place before pouring the molten metal.
Draw-bar – It is a rigid metal coupling device used to connect a powered machine (like a tractor or locomotive) to a load (like a trailer, agricultural implement, or train car) to transfer pulling force. It also refers to a clamping rod used to secure tools in machine tools like mills. It is also a bar used for lifting the pattern from the mould.
Draw bead – It is an insert or rib-like projection on the draw ring or hold-down surfaces which aids in controlling the rate of metal flow during deep draw operations. Draw beads are especially useful in controlling the rate of metal flow in irregularly shaped stampings.
Draw bead simulator – It is a mechanical testing device and computational modeling concept used in sheet metal forming. It measures and predicts the forces required to pull metal sheets through die beads, helping engineers optimize material flow, prevent tearing, and reduce wrinkles during stamping operations.
Draw-bench – It is the stand which holds the die and draw head used in drawing of wire, rod, and tubing. Drawbenches are heavy-duty industrial machines which pulls metal bars, rods, or tubes at room temperature through a smaller die. This cold plastic deformation process reduces the material’s cross-sectional area, elongates it, and improves considerably both its dimensional tolerance and surface finish.
Draw-bend test – It is a specialized metallurgical test used to evaluate the formability and spring-back characteristics of sheet metal. It simulates industrial stamping and pressing processes by pulling a metal strip over a curved die or cylinder while applying constant tension.
Draw depth – It is the depth of the drawn product.
Draw-down test – It measures how fluid pressure or water level drops over time when a well is pumped or produced at a constant rate. It helps engineers figure out underground reservoir limits, permeability, and well performance.
Draw forging – It is a process using two or more moving dies for producing shafts with constant or varying diameters along their length or tubes with internal or external variations. It is frequently incorrectly referred to as rotary forging.
Draw forming – It is a method of curving bars, tubes, or rolled or extruded sections in which the stock is bent around a rotating form block. Stock is bent by clamping it to the form block, then rotating the form block while the stock is pressed between the form block and a pressure die held against the periphery of the form block.
Draw frame – It is also called drawing frame. I) is a machine which combines, stretches, and straightens fibres strands (slivers). It passes multiple carded slivers through successive pairs of rollers moving at increasing speeds. This process aligns the fibres, blends them evenly, and reduces weight variations to create uniform yarn.
Draw head – It is a set of rolls or dies mounted on a draw-bench for forming a section from strip, tubing, or solid stock.
Drawing – It is a term used for a variety of forming operations, such as deep drawing a sheet metal blank, redrawing a tubular part, and drawing rod, wire, and tube. Drawing is the process of pulling material through a die to reduce the size, change the cross section or shape, or harden the material. It is a forming technique used to fabricate metal wire and tubing. Deformation is accomplished by pulling the material through a die by means of a tensile force applied on the exit side. In polymers, it is a deformation technique wherein polymer fibres are strengthened by elongation. In forging, it is an operation of working metal between flat dies to reduce the cross section and increase length. The normal drawing process with regard to sheet metal working in a press is a method for producing a cuplike form from a sheet metal disk by holding it firmly between blank-holding surfaces for preventing the formation of wrinkles while the punch travel produces the needed shape. In foundry, drawing means removing pattern from the mould or mould from pattern in production work.
Drawing and ironing – It is a sequential metal-forming process used to create deep, thin-walled hollow objects, such as beverage cans and automotive casings. The drawing phase transforms a flat metal blank into a cup, while the subsequent ironing phase reduces and uniformly smooths the cup’s walls.
Drawing, cold drawing – It consists of pulling of a work-piece through a fixed die at room temperature. It can reduce the size, change the cross section or shape, improve surface finish, improve tolerances or work-harden the material.
Drawing compound – It is a substance applied to prevent pickup and scoring during drawing or pressing operations by preventing metal-to-metal contact of the work and die. It is also known as die lubricant. In metalworking, it is a lubricant which has extreme-pressure properties.
Drawing dies – These are specialized, highly polished tools used to reduce the cross-section, change the shape, or elongate ductile metals through plastic deformation. Material is pulled (drawn) by tensile force through a precisely engineered hole, transforming it into thinner wires, rods, bars, or seamless pipes.
Drawing, engineering – In engineering, drawing can be defined as ‘a graphic representation of an idea, a concept, or an entity which actually or potentially exists in life’. It is a two-dimensional representation of three-dimensional objects. It is a graphic representation of an object, or a part of it, and is the result of creative thought. The drawing itself is a way of communication all necessary information about an abstract, such as an idea or concept or a graphic representation of some real entity, such as a spare part, an equipment, an assembly, a system, a facility, a tool, or a structure. The drawings prepared is to be clear, unmistakable in meaning, and there is not to be any scope for more than one interpretation.
Drawing, graphics – Graphics drawing refers to the process of creating visual representations on a display by manipulating pixel positions, colours, and patterns through different functions, such as drawing lines, shapes, and text.
Drawing-in – It refers to the inward movement or flow of sheet metal into a die cavity during a deep drawing or stretching operation. As the punch presses the metal blank, the outer edges are ‘drawn-in’ toward the centre to form 3D shapes like cups or shells.
Drawing of pattern – It is removing a pattern from a mould or a mould from a pattern in production work.
Drawing out – It is a stretching operation resulting from forging a series of upsets along the length of the work-piece.
Drawing process – It is an operation which involves pulling wire, rod, or bar through a die to decrease its cross-sectional area and increase its length, utilizing a combination of pulling and pressure forces.
Drawing quality – It is a quality designation of carbon steel, which typically contains less than 0.05 % carbon. This grade of steel is more ductile than commercial quality and is suitable for producing deep-drawn parts or any other parts needing severe deformation.
Drawing quality special killed (DQSK) steel – It is a type of mild steel which is completely deoxidized with aluminum, ensuring it is free from aging and suitable for applications needing high ductility and formability, such as deep drawing operations.
Drawing quality steels – These are flat rolled steel products which are produced either as rimmed steel or as aluminium killed steel. Special rolling and processing operations help in producing a product, which can stand extreme pressing, drawing or forming operations without creating defects.
Drawing ratios – Drawability can also be expressed in terms of LDR or percentage of reduction based on results of deep-drawing cup testing. The LDR is the ratio of the diameter ‘D’ of the largest blank which can be successfully drawn to the diameter of the punch ‘d’. It is given by the equation ‘LDR = D/d’. Percentage of reduction is then be defined by the equation ‘Percentage of reduction = [100(D – d)]/D’.
Drawing sheet – It is the medium on which drawings are prepared by means of pencils. Drawing sheets are normally of standard sizes. It has drawing space, title block and revision block table, grid reference system, sufficient margins, and the part list (bill of materials).
Drawing stage – It refers to the specific technical phase where conceptual ideas and designs are translated into standardized, precise 2D or 3D blue-prints and technical documentation using tools or software like CAD (computer aided design). This stage acts as the universal language for manufacturing, construction, and quality control.
Drawing stock – It is a hot-worked intermediate solid product of uniform cross section along its whole length, supplied in coils and of a quality suitable for drawing into wire.
Drawing stress (Sd) – It is the tensile force per unit area needed to pull a metal work-piece through a reducing die. It elongates the material and reduces its cross-sectional area. The fundamental formula is ‘Sd = F/A’, where ‘F’ is the pulling force and ‘A’ is the exit cross-sectional area.
Drawing technique – It is a method for producing nano-fibres by extending a polymer solution into fine strands while evaporating the solvent, utilizing visco-elastic polymers to withstand stress during the process. This technique allows for the separation of individual nano-fibres without damaging others, although it faces challenges such as time constraints and difficulty in controlling fibre diameter.
Drawing to size – It normally refers to drawing (manufacturing), a cold-working process where metal wire, rod, bar, or tubing is pulled through a tapered die to reduce its cross-sectional diameter, elongate it, and achieve a highly precise final dimensional size and superior surface finish.
Draw ironing – It is a secondary sheet metal stamping process. It happens right after deep drawing. A hollow cup is forced through a die to deliberately thin and lengthen the walls while maintaining a uniform, precise thickness and a smooth surface.
Draw marks – These are marring or scratching of a formed metal part by metal pickup on the punch or die.
Drawn fibre – It is the fibre with a certain quantity of orientation imparted by the drawing process by which it was formed.
Drawn-in scratch – It is a scratch occurring during the fabricating process and subsequently drawn over, making it relatively smooth to the touch.
Drawn-over-mandrel – It is a procedure for producing specialty tubing using a drawbench to pull tubing through a die and over a mandrel, giving excellent control over the inside diameter and wall thickness. Advantages of this technique are its inside and outside surface quality and gauge tolerance. Major uses include automotive applications and hydraulic cylinders.
Drawn product – It is a product formed by pulling material through a die.
Drawn shell – It is an article formed by drawing sheet metal into a hollow structure having a pre-determined geometrical configuration.
Drawn tube – It is a hollow product of uniform wall thickness, produced by cold drawing.
Draw peg – It refers to a tapered pin used during the assembly of joints. Driven through intentionally offset holes in overlapping components, the peg acts as a wedge which forces the pieces into rigid alignment and clamps the joint tightly together.
Draw plate – In metal forming, it is a circular plate with a hole in the centre contoured to fit a forming punch. It is used to support the blank during the forming cycle. In casting, it is a plate attached to a pattern for facilitating drawing of a pattern from the mould.
Draw point – It is an underground opening at the bottom of a stope through which broken ore from the stope is extracted.
Draw radius – It is the radius at the edge of a die or punch over which sheet metal is drawn.
Draw ratio – It is a critical parameter used to measure the severity and feasibility of a sheet metal drawing operation (such as deep drawing). It predicts whether a flat metal blank can be formed into a cup or hollow shape without tearing, thinning, or wrinkling.
Draw ring – It is a ring-shaped die part (either the die ring itself or a separate ring) over which the inner edge of sheet metal is drawn by the punch.
Draw screw – It is a specialized hand tool with an eyebolt or looped handle and a threaded end. It is screwed into drilled holes in metal patterns or tapped wooden rapping plates to lift, rap (loosen), and safely extract the pattern from the compacted moulding sand.
Draw solution – It is a highly concentrated liquid used in forward osmosis (FO) processes. Its main function is to naturally draw or ‘attract’ pure water through a semi-permeable membrane, separating it from a lower-concentration ‘feed’ solution, such as sea-water or waste-water. In forward osmosis, the draw solution is the fundamental driving force. It relies on a difference in osmotic pressure.
Draw spike – It is a tapered steel rod with a sharp point on one end (to drive into wood) and a loop or ring on the other, used in a foundry to gently loosen and lift patterns out of compacted molding sand.
Draw stock – It is the forging operation in which the length of a metal mass (stock) is increased at the expense of its cross section. In this, no upset is involved. The operation includes converting ingot to pressed bar using ‘V’, round, or flat dies.
Draw stress – It is the tensile stress applied at the exit of a die needed to stretch and reduce the cross-sectional area of a metal wire, rod, or tube. It is to exceed the material’s yield strength but stay well below its fracture limit.
Draw surface – It is also called drawing surface. It refers to the portion of a pattern which aligns vertically or at an angle, allowing the pattern to be cleanly pulled (drawn) from the moulding sand without breaking the mould.
Draw, surface – It is the appearance of shrink on the upper surface of a casting.
Draw wiping – It is also known as the subtractive drawing method. It is a technique where an artist tones an entire surface and uses an eraser, cloth, or brush to subtract or wipe away the medium to reveal highlights and create the drawing.
Draw-works – It is the heavy-duty hoisting and power-transmission mechanism on a rotary drilling rig. It acts as a giant winch, using a large rotating drum to spool a thick steel wire rope (the drilling line) up and down to raise or lower the drill string, casing, and heavy equipment in the wellbore.
Dredge – It is the sieve used to apply powdered porcelain enamel frit to the ware during dredging. It is also an excavation device designed to remove or mine sediments or minerals from under-water locations, utilizing scoops or suction hoses to extract material from the sea-bed, lake-bed, or river-bed.
Dredging – In dry process enameling, it is the application of dry, powdered frit to hot ware by sifting. It is also the removing of sediments and debris from the bottom of lakes, rivers, harbours, and other water bodies.
Dressing – It is the process of eroding the bond matrix in a grinding wheel surface after truing or grinding in order to expose the abrasive grains and hence improve grinding efficiency. It also consists of cutting, breaking down, or crushing the surface of a grinding wheel for improving its cutting ability and accuracy. It is also removing of dulled grains from the cutting face of a grinding wheel to restore cutting quality. In case of galvanizing, the coating is inspected after galvanizing, and irregularities are removed by dressing the surface by buffing or filing.
Dressing process – It is a procedure which involves truing or profiling an abrasive tool to ensure it conforms to the needed shape and texture for subsequent grinding. This process includes the removal of material through crushing and cutting mechanisms on the abrasive layer, frequently performed in the presence of process fluid to reduce tool wear.
Dried sand – It is the sand which has been dried by mechanical dryer prior to use in core making.
Drier – It is also spelled as dryer. It is a catalyst added to speed the cure of oil-based paints. Driers are frequently metal salts of carboxylic acids. Drier also refers to a specialized oven or piece of equipment used to remove moisture from sand moulds and cores before liquid metal is poured. Drying ensures the moulds do not produce gas defects or blowholes from trapped water vapour. The term can also refer to a gas torch used to remove surface projections like gates and risers. Drier is also a material, such as alcohol ammonium nitrate, sodium perborate and manganese oleate, added to a core or mould mixture to remove or reduce the water content.
Drier core – It is also called core drier. It refers to a temporary support tray or mould used to hold and retain the exact shape of a sand core while it goes through the high-temperature baking process. It prevents the uncured sand core from slumping or deforming before it hardens.
Drift – It is a flat piece of steel of tapering width used to remove taper shank drills and other tools from their holders. It is also a tapered rod used to force mis-mated holes into line for riveting or bolting. Sometimes it is called a drift pin. In mining, drift is a horizontal underground opening which follows along the length of a vein or rock formation as opposed to a crosscut which crosses the rock formation.
Drift current density – It is the electric current per unit cross-sectional area created when charge carriers (like free electrons or holes) move in a specific direction since an external electric field is applied.
Drifter – It is a hydraulic rock drill which is used to drill small-diameter holes for blasting or for installing rock bolts.
Drift expanding test – A test for the weld integrity of a welded tube, normally carried out to International Organization for Standardization standard ISO 8493. The test is considered passed if no cracks are detected in the tube or at the welded seam after the test. The drift-expanding test is normally performed on tubes having an outside diameter of 150 millimeters and a wall thickness no greater than 10 millimeters.
Drift flow – It is normally analyzed through the drift-flux model. It describes the macroscopic movement of a multi-phase mixture, such as gas-liquid or solid-liquid flows. Instead of tracking each phase independently, it treats the combination as a single equivalent mixture moving at an average velocity, with a specialized ‘drift velocity’ accounting for the relative slip between the different phases.
Drift flux model – It is a simplified two-phase flow engineering approach. It treats a fluid mixture (like gas-liquid) as a single pseudo-fluid moving together, but explicitly accounts for the relative velocity, or ‘slip’ between the two phases. Instead of tracking each phase independently, it uses a single mixture momentum equation.
Drift vector – It represents the deterministic, average direction and rate of change of a system’s state over time, especially in stochastic (random) or dynamic processes. It defines the predictable component of a system’s movement before adding random noise or disturbances.
Drift velocity – It is the average speed which free charge carriers, like electrons, gain inside a metal conductor when a person applies an electric field. Even though electrons bounce around randomly at high speeds, the electric field pulls them slowly toward the positive terminal.
DRI grade pellets – These are also known as acid pellets. The requirements of DRI (direct reduced iron) grade pellets are (i) low quantity of silica and alumina (less than 0.9 %), (ii) high basicity, (iii) low reduction disintegration, (iv) low sticking tendency, and (v) high reducibility. The requirements of BF (blast furnace) grade pellets are (i) high and consistent quality, (ii) high productivity, (iii) low energy demand, (iii) additives to optimize blast furnace process performance and (iv) pellets to match high basicity sinter.
Drill – It is a rotating end-cutting tool or machine used to create or enlarge a circular hole in solid materials. It relies on axial feed and rotational force to shear away material, spanning mechanical manufacturing, civil construction, and geotechnical resource extraction.
Drillability – It refers to the degree of difficulty in drilling into rock formations under specific conditions, and it serves to classify rock types in order to select appropriate drill bits that enhance drilling speed and reduce costs.
Drill bit – It is a rotary cutting tool mounted in a drill or machine to shear, crush, or bore cylindrical holes into a work-piece or geological formation. It converts rotational torque and axial feed force into material removal, ejecting debris through built-in flutes or fluid channels.
Drill collar – It is a heavy, thick-walled steel tube placed at the bottom of a drill string just above the drill bit. Its main job is to use gravity to push down on the bit so it can cut through rock. It also keeps the drill straight and stops the lighter pipes above it from bending.
Drill core logging – It is the process of recording geological observations of drill core either on paper or on computer disk.
Drilled hole – It is a cylindrical cavity created in a solid material by a rotating cutting tool (a drill bit) which removes material as chips. It is a main subtractive manufacturing process used to make paths for fasteners, alignment pins, or shafts.
Drill floor – It is also called the rig floor. It is the main working platform on a drilling rig. It sits directly beneath the derrick and houses the rotary table, driller’s console, and equipment used to assemble, lower, and retrieve the drill string.
Drill hole – It is a cylindrical cavity created in a solid material (such as metal, wood, plastic, or rock) using a rotating cutting tool or drill bit. It is a fundamental subtractive manufacturing and geo-technical operation used for fastening components, housing bearings, or exploring subterranean formations.
Drillhole collar – It is the identification post indicating past drill holes. Information about the hole is to be indicated by a tag and normally include drillhole identification number (drilling log), location, depth, azimuth, and dip).
Drill-indicated reserves – It is the size and quality of a potential ore-body as suggested by widely spaced drillholes. Normally, more work is needed before reserves can be classified as probable or proven.
Drilling – It consists of hole making with a rotary end-cutting tool having one or more cutting lips and one or more helical or straight flutes or tubes for the ejection of chips and the passage of a cutting fluid.
Drilling and blasting – The drilling and blasting process is a controlled engineering technique which uses specific hole patterns and high explosives to fracture and remove hard rock masses. It is widely applied in civil engineering, and mining to shape rock faces or clear paths for infrastructure. It is also a method of tunnel construction where holes are drilled into rock, packed with explosives, and subsequently detonated to facilitate excavation.
Drilling and completion technology – It is the combined set of engineering techniques, tools, and processes used to penetrate the earth’s surface and prepare a well-bore for the safe, efficient extraction of sub-surface oil, gas, or geothermal resources.
Drilling conditions – These conditions refer to the physical, mechanical, and environmental factors, such as rotational speed, weight on bit, and formation pressure, which dictate how a drill bit interacts with a material. Controlling these parameters ensures safe, efficient hole creation or resource extraction.
Drilling contractor – It is a specialized organization or individual that owns, maintains, and operates a drilling rig. They provide the physical equipment and trained onsite crew needed to drill bore-holes for oil, gas, water, or mining projects, working under the direction of an operating organization.
Drilling cost – It is the total financial expense needed to plan, bore, and construct a bore-hole or production well down to a target depth. It serves as a core economic metric used to optimize drilling efficiency, evaluate project feasibility, and prepare project budgets like an ‘authorization for expenditure’ (AFE).
Drilling dynamics – It is the real-time study, measurement, and analysis of mechanical behaviours, forces, and vibrations acting on a drill string and bit. It blends fluid, solid, and rock mechanics to optimize penetration rates, prevent equipment failure, and control destructive downhole vibrations.
Drilling efficiency – It evaluates the ratio of useful mechanical energy delivered to the rock against the total energy input applied by the drilling system. It is normally quantified using mechanical specific energy (MSE), the energy needed to excavate a unit volume of rock, where lower mechanical specific energy values indicate higher mechanical effectiveness.
Drilling engineering – It is a specialized branch of engineering focused on designing and executing procedures to bore holes into the earth safely, efficiently, and economically to extract sub-surface resources like minerals, oil, gas, water, or geothermal energy.
Drilling equipment – It refers to mechanical systems and heavy machinery used to create circular holes in solid materials like metal, wood, concrete, or rock strata. It operates by rotating a cutting tool (drill bit) at high speeds and applying axial force or impact to remove material.
Drilling fluid – It is widely known as drilling mud. It is a specialized liquid or gas pumped down a well-bore during oil, gas, or water drilling to cool the bit, carry away rock cuttings, and control underground pressure.
Drilling fluid density – It is normally called mud weight. It is the mass or weight of drilling mud per unit volume. It is typically measured in grams per cubic centimeter. This property creates the necessary hydrostatic pressure in the wellbore.
Drilling fluid parameters – These are the measurable physical, chemical, and rheological properties of drilling mud (such as density, viscosity, and filtration rate) engineered to control sub-surface pressures, stabilize the wellbore, cool the drill bit, and lift rock cuttings to the surface.
Drilling hole – It is also called bore-hole. It is a circular cross-section opening cut into solid materials like metal, wood, or the earth’s crust using a rotating or hammering drill bit. It is used for fastening parts, taking soil samples, or finding underground resources.
Drilling hydraulics – It is the application of fluid mechanics to manage the circulation of drilling fluids (mud) through a well-bore. It optimizes pump pressure, fluid velocity, and hole cleaning to cool the bit, remove rock cuttings, and maintain well-bore stability.
Drilling line – It is a heavy-duty, high-strength wire rope used in the hoisting system of an oil, gas, or water well drilling rig. It supports, lifts, and lowers heavy loads like the drill string and casing into and out of the well-bore.
Drilling machine – It is one of the cast house equipment used for drilling the tap hole during its opening.
Drilling method – It is a systematic process of using mechanical force, rotation, or percussion through a drill bit to penetrate solid materials or the earth’s crust, creating a precise cylindrical hole for manufacturing, construction, or resource extraction.
Drilling mud filtrate – It is the liquid phase of a drilling fluid which separates from the suspension and is forced under differential pressure through the filter cake and into the pores of a permeable sub-terranean formation.
Drilling operation – It is a cutting or excavation process which uses a rotating tool (a drill bit) to create or enlarge a circular hole in solid materials like metal, wood, or the earth’s crust.
Drilling optimization – It is the systematic process of selecting operational parameters to minimize total well costs and maximize drilling efficiency. It balances safety, equipment limits, and hole quality while increasing the rate of penetration (ROP) and reducing non-productive time (NPT).
Drilling parameters – These are the adjustable operational values and measurable factors controlled during a drilling process. They dictate how a tool or drill bit breaks rock or metal to advance a bore-hole efficiently, safely, and at the lowest cost.
Drilling platform – It is a large structure equipped to support rotary drilling rigs, heavy machinery, power generation units, and crew quarters. It is used to drill, evaluate, and complete oil and gas wells beneath the sea-bed.
Drilling project – It is a planned operational undertaking to create a deep, narrow borehole into the earth’s crust safely and economically. Its core purpose is to explore, evaluate, or extract subterranean resources, such as oil, natural gas, water, or minerals, or to test geotechnical properties.
Drilling rate – It is normally called the pate of Penetration (ROP) or penetration rate. It is the speed at which a drill bit breaks rock or material to deepen a bore-hole. It is typically measured in meters per hour.
Drilling rig – It is an integrated mechanical system which creates deep holes or bore-holes into the earth’s sub-surface for extracting natural resources like minerals, oil, natural gas, and water, or for geotechnical testing and construction.
Drilling riser – It is a large-diameter vertical pipe that connects a floating surface drilling rig to a sub-sea blow-out preventer (BOP) stack on the sea-bed. It acts as a temporary extension of the well-bore, returning drilling mud to the surface and guiding tools down-hole.
Drilling speed – It normally refers to cutting speed, the linear peripheral speed at the outer diameter of the drill bit as it cuts into the work-piece, typically measured in meters per minute. It is distinct from spindle speed (revolutions per minute, rpm), which measures how fast the tool rotates.
Drillings, test – These consist of chips, or small particles of metal removed from a test sample for chemical analysis.
Drilling structure – It refers to the physical tower or framework, such as a derrick or mast, on a drilling rig designed to support, lift, and suspend heavy loads like the drill string and casing. It provides the vertical clearance and structural integrity needed to lower or pull hundreds of meters of steel pipe into and out of the bore-hole.
Drilling technique – It is a specific method and tool-set used to cut, crush, or penetrate solid materials, such as rock, metal, or soil, to create a cylindrical hole. It combines mechanics and material science to extract resources or assemble structures.
Drilling technology – It is the set of specialized techniques, equipment, and operational methods used to penetrate the earth’s surface or hard materials. It creates narrow bore-holes for resource extraction, civil construction, and geological exploration, blending mechanics, fluid dynamics, and material science.
Drilling unit – It has two main meanings namely an offshore floating or bottom-supported vessel / platform designed to drill bore-holes (known as a mobile off-shore drilling unit or MODU), or a legal / technical land area allocated for a single oil or gas well.
Drill pipe – It is the pipe used in the drilling of an oil or gas well. Drill pipe is the conduit between the wellhead motor and the drill bit. Drilling mud is pumped down the centre of the pipe during drilling, to lubricate the drill bit and transmit the drilled core to the surface. Because of the high stress, torque and temperature associated with well drilling, drill pipe is a seamless product.
Drill pipe body – It is the long, seamless, hollow steel tube which forms the main middle section of a drill pipe. It spans the distance between the threaded end joints, serving to transmit rotational power, carry drilling fluid, and withstand heavy tension and twisting forces deep inside a well.
Drill pipe joint – It is normally called a tool joint. It is the heavy-duty, threaded connection mechanism welded to each end of a hollow drill pipe segment. It consists of a male pin connection and a female box connection used to couple single pipe joints together into a continuous, high-strength drill string.
Drill pipe pressure – It normally refers to either the fluid circulating pressure inside the drill string or the internal structural pressure the pipe body can safely withstand before bursting.
Drill-ship – It is a maritime vessel outfitted with a drilling rig, a central derrick, and a moon-pool, engineered specifically to perform exploratory and scientific core drilling in deep and ultra-deep ocean waters.
Drill stem test – It is a procedure used to evaluate the commercial viability, pressure, permeability, and production capacity of a geological formation. It acts as a temporary completion, allowing engineers to sample reservoir fluids and measure dynamic flow pressures before installing permanent well casing.
Drill string – It is a connected column of hollow steel pipes and mechanical tools which links the surface rig to the drill bit, serving to transmit rotational torque, direct axial weight, and deliver high-pressure drilling fluid down-hole.
Drill string component – It is an individual tubular section, mechanical tool, or accessory joined together to form the continuous column from the surface rig down to the drill bit in rotary drilling. It transmits torque and axial force, and carries drilling fluid.
Drinking water – It is that water which is used in various production shops and canteens of the steel plant for drinking purpose. The quality of drinking water is to be maintained at the level which is fit for human consumption.
Drinking water purification – It is the process of removing harmful chemicals, bad germs, tiny particles, and dirty gases from raw water. The main goal is to make the water safe, clean, and healthy for people to drink.
Drinking water standards – These standards describe the quality parameters set for drinking water. Water can contain many harmful constituents, yet there are no universally recognized and accepted international standards for drinking water. Even where standards do exist, the permitted concentration of individual constituents can vary by as much as ten times from one set of standards to another ser of standards.
Drinking water treatment – It is a multi-step physical, chemical, and biological process which purifies raw water from natural sources like rivers or ground-water to make it safe, clean, and pleasant for human consumption.
Drip – It typically refers to molten metal or slag which flows downward in discrete drops, as observed in processes like smelting, welding, or drop casting. It describes the liquid state of a material in drops, or the fluid loss of a metal / alloy.
Drip feed (drop feed) lubrication – It is a system of lubrication in which the lubricant is supplied to the bearing surfaces in the form of drops at regular intervals.
Drip pan conveyor – It is a conveyor with a built-in drip pan to catch and contain liquid spillage, necessitating regular cleaning and inspections.
Dripping zone– Dripping zone plays a crucial role in modern high productivity BFs. It affects production rate, hot metal quality, and process efficiency. Dripping zone is a four-phase region, where gas, solid, liquid, and powder coexist with each other. In this zone, solid and liquid flow downward driven by gravity, while gas and powder suspended in the gas flow upward due to the pressure force. The flow of four phases in this zone is considerably different from that in the upper shaft region because of the geometry and the presence of deadman zone at the centre and discrete raceways at the periphery.
Drip short – It is the transient downward voltage spike which occurs when a molten metal droplet is in contact with both the electrode and the molten pool. The number of shorts occurring in a given time period is proportional to the arc gap.
Drip-short frequency – It is the rate at which molten metal droplets bridge the gap between an electrode and the melting pool, momentarily shorting the electrical circuit. This metric is mainly used in specialized processes like vacuum arc remelting (VAR) and electro-slag remelting (ESR).
Drive – It consists of unit which is used to provide movement power for a conveyor. Parts normally include motor and reducer, chain, sprockets, and more.
Drive alignment – It is the process of ensuring proper alignment between the drive pulley and other conveyor components, demanding regular inspections to prevent belt misalignment.
Drive assembly – It is a mechanical unit which transmits power and rotational force (torque) from a power source (like an engine or motor) to a driven component (like wheels, propellers, or conveyor belts). It integrates components such as shafts, gears, and joints.
Drive axle – It is an important mechanical component which transmits torque and rotational power from a vehicle’s transmission or differential to the drive wheels, propelling the vehicle forward or backward while simultaneously supporting a portion of the vehicle’s weight.
Drive cap adapter – It is a steel unit designed to connect specific type of pile to a specific hammer. It is normally connected to the hammer by steel cables.
Drive cap insert – It is the unit which fits over the top of pile, holding it in line and connecting it to the adapter.
Drive cap system – It is the assembled components used to connect and transfer the energy from the hammer to the pile.
Drive chain – It is the mechanical link transmitting power in chain-driven conveyor systems, needs regular lubrication and tension adjustments.
Drive configuration – It is the specific arrangement, layout, and parameter setup of a power-transmission or motor-control system (such as mechanical gears, electric inverters, or robotic wheels) which dictates how energy flows to control speed, torque, and movement.
Drive, electrical – It is a system in which the motor is located and makes it spin. The electrical drive controls the electrical motor.
Drive gear – It is also called driving gear. It is that gear among a pair of gears which that mesh, which transmits the rotational motion of a motor or other device through the drive shaft.
Drive hammer – It is also called pile-driving hammer. It is a heavy mechanical device used to deliver powerful vertical impact blows to force structural elements like piles, sheet piling, or large pins deep into the ground to build stable foundations.
Drive head – It is a protective cap used when hammering pipes or casings into the ground. It is also the-read / write component in a computer disk drive, or a driving pressure / force in fluid mechanics.
Drive index – It very frequently refers to a reservoir drive index, which quantifies the fractional contribution of individual natural energy mechanisms pushing oil or gas to the surface. (Alternatively, in mechanical automation, index drives are precision mechanical systems used to start, stop, and position components in repetitive cycles).
Drive-line – It is the set of components which transfers power from a vehicle’s transmission to the drive wheels. It turns engine torque into the kinetic energy needed to move the vehicle forward or backward.
Drive machines for mechanical presses – It is the power system which converts a motor’s rotary motion into linear pressing force. It relies on a flywheel, clutch, and mechanical linkage to drive a ram downward, plastically deforming, stamping, or cutting metal work-pieces without producing chips.
Drive, mechanical – It consists of a series of components which manages the transmission. This power can be channeled to power other equipment like pumps, blowers, air compressors, and other common industrial machinery.
Drive mechanism – It refers to the thermodynamic or mechanical process which causes changes within a material, such as dislocation motion, grain growth, or phase transformations. The concept of a drive mechanism applies to two main contexts namely physical / atomic processes, and industrial manufacturing hardware.
Drive module – It is a self-contained unit which integrates an electric motor, power electronics (such as an inverter), and a mechanical transmission or gearbox to control motion, torque, and speed. It converts electrical energy into controlled mechanical power for automotive, industrial, and robotics systems.
Driven circuit – It is an electrical or electronic system which receives a continuous energy input or excitation from an external source, such as a voltage, current, or signal generator. This is distinct from a source-free circuit, which simply discharges its internally stored energy.
Driven component – It is the final machine, device, or mechanical part which receives power, energy, or motion from a separate power source or drive component (like a motor or engine) to perform work.
Driven equipment – It is the machinery which receives mechanical or electrical power from a separate power source, known as a prime mover or driver, to perform an operational task. It converts input energy into mechanical work, fluid flow, or material movement.
Drive energy system – It is normally referred to as an electric drive or drive power. It is an electro-mechanical set-up which converts electrical or stored chemical energy into controlled mechanical motion. It regulates speed, torque, and direction to power industrial machinery, vehicles, and robotics.
Driven gear – It bis also called output gear. It is the component which receives rotational motion and torque through the mechanical meshing of its teeth from a driving gear. It does not connect directly to a primary power source.
Driven membrane process – It is a separation technique where a physical or chemical force moves specific fluids, molecules, or ions through a semi-permeable barrier. The membrane selectively lets some particles pass while blocking others, based on size, charge, or chemical traits.
Driven oscillation – It is also called forced oscillation. It is a repeating movement in a system caused and maintained by an external periodic force. It overcomes energy lost from friction or damping, forcing the system to vibrate at the frequency of the applied source.
Driven pulley – It is an output component in a belt or cable drive system which receives rotational motion and power from a connecting belt, rope, or chain, rather than being directly attached to a power source.
Driven pump – It is a fluid-moving device powered by an external energy source (a prime mover) such as an electric motor, internal combustion engine, air pressure, or magnetic field. The prime mover transfers mechanical or physical energy to the pump’s internal mechanism, like an impeller, piston, or diaphragm, to create flow and pressure.
Driven reactor – It very frequently refers to an accelerator-driven sub-critical reactor (ADSR). It is a nuclear system where a sub-critical core cannot sustain a chain reaction on its own. It relies on an external particle accelerator to shoot high-energy particles into a target, producing the extra neutrons needed to drive the fission process.
Driven shaft – It is frequently contrasted with a driving or active shaft. It is a mechanical component which receives rotational power and torque from another source and delivers it to a load or output component.
Drive pins – These are the pins which fit into the bottom of a ball valve stem and engage corresponding holes in the ball. As the operator turns the stem, the drive pins turn the ball. The drive pins transmit the drive torque by shear. The drive pins can be replaced by a tang-drive connection integrally machined in the valve stem.
Drive power – It is the rate of energy transfer or mechanical work delivered by a drive system (such as an electric motor, engine, or hydraulic actuator) to move or operate a load. It defines the capacity needed to overcome resistance, maintain speed, and handle system dynamics.
Drive pulley – It is the pulley which is responsible for transmitting power to the conveyor belt, needing periodic assessments for wear, balance, and alignment.
Driver – It is a component, circuit, or programme which controls, operates, or supplies power to another device, sub-system, or system. It acts as a translator or amplifier between a low-power control source and a high-power or hardware-dependent load.
Driver circuit – It is an electronic stage which acts as a physical interface between a low-power control source (like a micro-controller) and a high-power load (like a motor or power transistor). It amplifies weak control signals to supply the necessary voltage and current levels needed for proper, efficient operation.
Driver circuitry – It is an electronic interface which boosts low-power control signals to operate a high-power load or a distinct component like a motor, LED (light emitting diode), or power transistor. It regulates current and voltage, matches impedance, and protects sensitive logic units from electrical feedback.
Drive reservoir – It is a geological formation where natural sub-surface energy, such as fluid expansion, gas pressure, or aquifer influx, pushes stored oil, gas, and water through rock pores and out toward a well-bore. This natural energy source dictates production strategies, pressure drops, and overall recovery rates.
Driver model – It is a mathematical or logical representation of human driving behaviour or vehicle control logic. It simulates how a driver perceives the environment, processes data, and acts (through steering, braking, or acceleration) to guide a vehicle safely along a desired path.
Driver parameter – It covers how physical, electronic, or behavioural variables are set to control hardware, software, or simulation models. Depending on the engineering discipline, it refers to electronic drive configurations, software interfaces, or human-driver simulation models.
Drive roll – It is also called drive roller. It is a powered cylindrical component which transmits rotational force, torque, or linear motion to move materials, feed wires, or drive belts through frictional contact.
Driver stage – It is an intermediate circuit which amplifies signals from a low-power controller or logic source to provide the necessary current, voltage, or impedance characteristics needed to properly operate a high-power output stage or external load.
Driver state – It refers to the quantified real-time assessment of a human operator’s physical, cognitive, and mental readiness. It classifies whether a driver is alert, fatigued, distracted, or overloaded to manage safe vehicle control or system handovers.
Drive-shaft – It is a component for transmitting mechanical power and torque and rotation. It is normally used to connect other components of a drive train which cannot be connected directly because of distance or the need to allow for relative movement between them.
Drive sprocket – It is a toothed wheel connected to a power source’s output shaft. Its teeth mesh with a roller chain or track to convert rotary motion into linear pulling force, transmitting power without slip to a driven sprocket.
Drive system – The drive system frequently offers substantial opportunities to improve energy efficiency and to lower overall system operating costs. There are two principal types of drive systems (i) direct drive, and (ii) belt drive. Gear drives are also used but are less common.
Drive train – It consists of all parts of a valve drive between the operator and the obturator, including the obturator, but excluding the operator. It also includes the anchor pin.
Drive unit – It is the motorized component propelling the conveyor belt, necessitating regular inspections for optimal performance.
Drive unit tensioner – It is a device for maintaining proper tension in the conveyor belt, needing periodic adjustments to prevent slack or excessive tension.
Driving cycle – It is a standardized speed-versus-time data profile used to simulate real-world vehicle operation. It evaluates fuel consumption, tailpipe emissions, electric vehicle range, and power-train component durability on a chassis dynamometer or in computer simulations.
Driving energy – It is frequently referred to as drive energy or drive power. It is the total input energy or power needed to move, operate, or actuate a mechanical system, vehicle, or industrial process against resistive forces.
Driving force – It is the thermodynamic motivation which pushes a material to change its state or structure, such as minimizing its internal energy or relieving a chemical potential gradient. It dictates the direction and speed of processes like diffusion, solidification, and phase transformations. It is a factor which keeps a system away from equilibrium and facilitates flows within dissipative systems, allowing for energy dissipation through processes such as friction and interaction with the surroundings.
Driving gear – It is the component which receives power directly from a motor or engine and transmits rotational motion and torque to a mating gear, known as the driven gear. It is defined by its active functional role rather than its physical size or tooth count.
Driving piston – It is a sliding cylindrical component in a reciprocating engine or machine which moves back and forth inside a cylinder, directly translating the high-pressure energy of expanding combustion gases into mechanical force, or vice versa.
Driving rain – It is also called wind-driven rain. It is rain propelled at an angle against vertical or sloped surfaces by strong wind. It creates an oblique moisture load that heavily impacts the durability, waterproofing, and structural integrity of building envelopes.
Driving ram – It is normally called a pile-driving hammer ram. It is the heavy reciprocating weight or piston inside a pile driver. It is raised by gravity, steam, diesel combustion, or hydraulics and then dropped or accelerated downward to strike the top of a structural pile, transferring kinetic energy to force the pile into the ground.
Driving rod – It is frequently a connecting rod. It is a mechanical link used to transfer power from a driving mechanism, like a piston, to another moving part, such as a crankshaft or driving wheel. It converts linear motion into rotary motion.
Driving roller – It is a powered cylindrical component which transmits rotational force and torque through friction to move materials, drive belts, or rotate other mechanisms. It receives energy from an external motor or an internal integrated drive and propels an assembly forward.
Driving shaft – It is a mechanical part which sends twisting power and spin movement from a motor or engine to another part of a machine. It bridges gaps between parts that cannot touch directly.
Driving simulation – It is a multi-sensory system which allows a human driver or an automated system to perceive and control virtual vehicle movements in real time. It combines vehicle dynamics physics, visual displays, and motion feedback to test vehicle designs and human behaviour safely.
Driving simulator – It is an advanced multi-sensory system which allows a human driver to interact with a virtual vehicle and road environment. It combines real-time vehicle dynamics models, visual graphics, motion cueing, and audio feed-back to replicate real-world driving conditions for testing and research.
Driving velocity – It typically refers to the designated or actual forward speed and directional rate of travel of a vehicle, or the operational speed enforced by a ‘driving’ force in a dynamic system.
Droop characteristic – It is an intentional, proportional reduction in a system parameter, such as a generator’s frequency or terminal voltage, as its load or output power increases. This self-regulating feed-back mechanism allows multiple power sources to share electrical loads stably in parallel without needing complex centralized communication.
Droop coefficient – It is a proportional control parameter which defines how much a system’s output variable (like frequency or voltage) drops as its load (like active or reactive power) increases. It acts as the slope of the linear droop control curve.
Droop control – It is a decentralized method used in power systems to let parallel generators or inverters share electrical loads. It lets a unit lower its frequency or voltage slightly as the power demand goes up. This simple local action helps balance the load without needing a central control wire.
Droop controller – It is a decentralized control method used in electrical power systems and micro-grids. It lets parallel power sources share active and reactive loads by allowing system frequency and voltage to drop slightly as the load increases, removing the need for high-speed communication lines.
Droop gain – It is also called droop coefficient. It is the proportional multiplier which dictates how much a power source, like a generator or inverter, changes its output in response to a system deviation, such as a drop in grid frequency or terminal voltage.
Droop mode – It is also called droop control. It is a passive control strategy used in power systems where a generator’s output frequency or voltage drops proportionally as its electrical load increases. This intentional adjustment allows multiple power sources to run in parallel and share total system loads stably without needing complex communication lines.
Droop parameter – It is also called droop setting. It is the intentional proportional decrease in a generator’s or inverter’s frequency (or voltage) as its output active (or reactive) power increases. It allows multiple power sources running in parallel to share electrical loads stably without needing direct communication links.
Droop setting – It is a control configuration for power generators or turbines where the output frequency or speed decreases slightly as the electrical load increases. Typically set between 4 % and 5 %, it allows multiple generators running in parallel to share loads stably without conflicting with each other.
Droop speed control – It is a method used in power generators. It lowers the speed or frequency of a machine as its load goes up. This drop lets several generators run together on the same grid. It helps them share the electrical load safely and keeps the system stable.
Drop – It is also called drop-out. It is a casting imperfection because of a portion of the sand dropping from the cope or other overhanging section of the mould. In the fabrication process, drop refers to the left-over or scrap material which remains after the main components have been cut or shaped. Managing and minimizing drop is crucial for cost efficiency and sustainability in construction and manufacturing. In case of valves, there is a drop in set (outlet) pressure of a regulator or control valve because of the travel of its valve or poppet, as the required flow increases from low to maximum. A slight change in the control spring length due to the valve travel will result in spring force variations, translating into a change of set (outlet) pressure.
Drop ball – It is also called breaker ball. It is a heavy, spherical or pear-shaped iron or steel weight. It is hoisted to a height by a crane and repeatedly dropped onto large pieces of solid metal to shatter or break them into manageable sizes for remelting. It is also a ball which is dropped or pumped through the wellbore tubulars to activate a downhole tool or device. When the ball is located on a landing seat, hydraulic pressure generally is applied to operate the tool mechanism.
Drop ball impact test – It is a standardized procedure used to evaluate the impact resistance, fracture toughness, and energy absorption of materials like plastics, glass, ceramics, and electronic screens.
Drop cable – It is a type of cable which includes different quality and feature options, such as differing levels of shielding, support messengers, and the ability to carry telephony or power alongside RF (radio frequency) signals, while also adhering to electrical and fire codes for safety. Drop cable is also the final physical link connecting a main distribution network (such as a utility pole or street terminal) to an end-user’s building or home. It handles the critical ‘last mile’ of communication and power systems.
Drop compensator – It is very frequently known in engineering as a line drop compensator (LDC). It is a control circuit or device used in electrical power systems to adjust voltage output. It automatically raises supply voltage at a regulator or transformer to cancel out the voltage loss (resistive and reactive drops) which occurs along long transmission lines or cables, ensuring proper voltage reaches the remote load.
Drop controllers – Electro-magnets hold a load by means of magnetic lines of force which are generated by the magneto-motive force of the energized magnet. When the magnet is de-energized, residual lines of force can remain if there is close contact between the magnet and load. Reverse current drop controllers are used to apply reverse current to the magnet for cancellation of these residual lines. This cancellation results in faster release of the load.
Drop diameter – It is the linear width or size of a liquid droplet. It is normally measured in micro-meters. In sprays and aerosols, it describes individual particles or statistical averages like the Sauter mean diameter.
Drop dynamics – It is the study of how liquid drops behave, move, change shape, and interact with surfaces or other drops. It combines forces like surface tension, inertia, and viscosity.
Drop energy – It typically refers to the energy an object gains or converts as it falls from a height due to gravity. This energy is primarily gravitational potential energy, which is converted into kinetic energy during the fall. The quantity of energy an object has when falling is also known as ‘fall energy’. It is a crucial factor in fall protection systems and impact force calculations. In case of conveyors, it is the energy caused by the drop of the conveyed material onto the conveyor belt. It depends on the lump size, and drop height etc.
Drop etching – In metallography, it is placing of a drop of etchant on the polished surface.
Drop forging – It is the forging got by hammering metal in a pair of closed dies for producing the form in the finishing impression under a drop hammer. It is also the forging method needing special dies for each shape.
Drop gate – In hydraulics and dams, it is a vertical-moving gate which drops to release excess water. It also refers to a runner directing molten metal into a mould. It is a term for a pouring gate or runner leading directly into the top of the mould.
Drop hammer – It is a term which is normally applied to forging hammers in which energy for forging . is provided by gravity, steam, or compressed air.
Drop hammer forming – It is a process for producing shapes by the progressive deformation of sheet metal in matched dies under the repetitive blows of a gravity-drop or power-drop hammer. The process is restricted to relatively shallow parts and thin sheet from around 0.6 millimeters to 1.6 millimeters).
Drop hammer, gravity – It consists of an anvil or base, supporting columns which contain the ram guides, and a device that returns the ram to its starting position. The energy which deforms the work-piece is derived from the downward drop of the ram. The height of the fall and the weight of the ram determine the force of the blow. In a simple gravity-drop hammer, the upper ram is positively connected to a board (board drop hammer), a belt (belt drop hammer), a chain (chain drop hammer) or a piston (oil-drop, air-drop, or steam-lift drop hammer).
Drop hammer, power – In a power-drop hammer, the ram is accelerated during the down-stroke by air, steam, or hydraulic pressure. This equipment is used almost exclusively for closed-die (impression-die) forging.
Drop-in defect – It is very frequently known as a sand drop in foundry. It is an irregularly shaped projection on the cope (upper) surface of a metal casting. It occurs when a weak section or hanging projection of the moulding sand falls or collapses into the mould cavity before or during the pouring of molten metal. When the fallen sand is displaced by the liquid metal, it creates a recessed cavity, and the fallen sand itself can become trapped inside the solidifying casting as a sand inclusion.
Droplet – It is a small column of liquid, bounded completely or almost completely by free surfaces. In pelletizing disk, droplet state occurs when the agglomerate is kept together by the cohesive force of the liquid.
Droplet combustion – It is the physical and chemical process where a liquid fuel drop evaporates in a hot, oxidizing gas (like air), producing a vapour envelope which burns as a diffusion flame. It is the fundamental building block for understanding spray combustion in diesel engines, gas turbines, and rockets.
Droplet erosion – It is the erosive wear caused by the impingement of liquid droplets on a solid surface.
Droplet growth – It is the physical process where liquid droplets increase in size through mass transfer (such as direct vapour condensation) and momentum-driven merger (such as the coalescence of adjacent droplets). It governs thermal performance in condensers, spray systems, and phase-change heat exchangers.
Droplet impact velocity – It refers to the speed at which a droplet strikes a surface, influencing different outcomes such as spreading, rebounding, and splashing, as observed in experiments studying droplets impacting on solid surfaces.
Droplet model – It is a mathematical or computational representation used to analyze the behaviour, kinematics, and thermodynamics of discrete liquid drops suspended in a gas or immiscible fluid. It tracks forces, evaporation, deformation, and combustion in multiphase flows like sprays and fuel injectors.
Droplet nucleus – It is the tiny, dried residue (typically 5 micro-meters or less in diameter) left behind after a liquid respiratory droplet evaporates. In environmental control, and HVAC (heating, ventilation, and air conditioning) design, these micro-particles are critical since they stay suspended in the air for hours and move easily on-air currents, driving airborne disease transmission.
Droplet phase – It is also called dispersed phase. It is the discontinuous liquid component suspended within a surrounding continuous fluid (gas or another immiscible liquid), separated by a distinct interfacial boundary governed by surface tension and hydrodynamic forces.
Droplet size – It refers to the diameter of liquid drops created during atomization, normally measured in micro-meters. Since a spray nozzle produces millions of drops of different sizes, engineers use statistical parameters, like the volume median diameter (Dv0.5) where 50 % of the volume is in smaller drops and 50 % in larger drops, to define and control spray performance.
Droplet size distribution – It is the statistical range and relative frequency of liquid droplet diameters in a spray, mist, or emulsion. It determines total surface area, evaporation rates, and chemical reactivity, which are critical for designing fuel injectors, and industrial scrubbers.
Droplet stage – It mainly refers to a phase in material solidification (such as the final scattered liquid pools between grains during metal cooling) or a distinct sequential phase in micro-fluidic droplet generation (where a pinched-off liquid drop forms inside a continuous fluid channel).
Drop motion – It describes the movement of an object falling vertically under the sole influence of gravity (free fall), or the physical displacement and sliding dynamics of liquid droplets on solid surfaces.
Drop of liquid – It is a small, rounded mass of fluid bounded completely or almost completely by a free surface. It forms because of the surface tension when liquid collects at a tip, condenses from vapour, or breaks apart from a larger mass.
Drop-on-demand (DoD) inkjet – It is a printing method where the print-head ejects discrete droplets of ink onto a substrate only when explicitly needed by digital data, avoiding a continuous fluid stream.
Drop-out – It is also called drop-off. It is the sand falling from the cope of a mould. Drop-out is a manufacturing defect where the mould wall or core fails under the extreme heat and pressure of molten metal. The molten metal breaches the mould, causing part of the mould to collapse or wash away. This results in a malformed or ruined metal casting. Drop-out also refers to a regularization technique in artificial intelligence where random neurons are turned off during training, or a technical failure mode in electronics and fluid pipelines representing a sudden loss of signal, voltage, or flow separation.
Drop-out voltage – It is the minimum voltage difference needed between the input and output for the regulator to function properly.
Dropped edge – It is a continuous, downward edge deflection.
Dropping the bottom – It refers to the shutdown process of a cupola furnace where the supporting props are removed so that the hinged bottom doors swing open. This allows the remaining molten slag, unburnt coke, and unmelted charge to drop out of the furnace.
Drop point – Drop point is the temperature at which grease passes from the semi-solid to the liquid state. Hence, it determines the upper temperature limit for the applicability of grease.
Drop size – It means the physical diameter or volume of a liquid droplet. In fluid engineering and spraying systems, it describes the size spectrum of droplets created during atomization. In business and sales, it can also refer to the volume of product delivered in a single transaction.
Drop size distribution – It is a statistical measurement which describes the range and relative number or volume of liquid droplets of varying diameters within a spray, cloud, or emulsion. It defines whether a spray contains uniform droplets or a wide mix of large and small sizes.
Drop-through – It is an undesirable sagging or surface irregularity, normally encountered when brazing or welding near the solidus of the base metal, caused by over-heating with rapid diffusion or alloying between the filler metal and the base metal.
Drop-through die – It is a press tool design where cut blanks or slugs are pushed all the way through the die cavity and out the bottom. This continuous gravity-fed process relies on a tapered opening which prevents jamming and allows stamped parts to fall freely onto collection bins or conveyors.
Drop tube furnace – It is a vertical laboratory reactor where solid or liquid particles fall through gravity through a hot, precisely controlled thermal zone. It simulates rapid industrial processes like coal combustion, bio-mass gasification, and flash pyrolysis by exposing particles to high heating rates and short residence times.
Drop-weight test – It is conducted by subjecting a series (usually four to eight) of samples to a single impact load at a sequence of selected temperatures to determine the maximum temperature at which a sample breaks. The impact load is provided by a guided, free-falling weight with energy of 340 joules to 1,630 joules depending on the yield strength of the steel to be tested. The samples are prevented by a stop from deflecting less than a centimeter. This is a ‘go – no-go’ test method in which the sample either breaks or fails to break. It is surprisingly reproducible.
Drop-weight tear test (DWTT) – It uses a test sample which resembles a large Charpy test sample. The test sample is 76 millimeters wide by 305 millimeters long, supported on a 254 millimeters span. The thickness of the sample is the full thickness of the material being tested. The samples are broken by either a falling weight or a pendulum machine. The notch in the sample is pressed to a depth of 5 millimeters with a sharp tool-steel chisel having an angle of 45-degree. The resulting notch root radius is around 0.025 millimeters. One result of the test is the determination of the fracture appearance transition curve. The average percent shear area of the broken samples is determined for the fracture area neglecting a region of ‘one thickness’ in length from the root of the notch and ‘one-thickness’ from the opposite side of the sample. These regions are ignored since it is thought that the pressing of the notch introduces a region of plastically deformed material which is not representative of the base material. Similarly, the opposite side of the sample is plastically deformed by the hammer tup during impact. The fracture appearance plotted against temperature defines an abrupt transition in fracture appearance. This transition has been shown to correlate with the transition in fracture propagation behaviour in cylindrical pressure vessels and piping.
Dross – It is the scum which forms on the surface of molten metal largely because of oxidation but sometimes because of the rising of impurities to the surface. It is also oxide and other contaminants which form on the surface of molten solder. In case of galvanizing, steel is reacting with molten zinc forms small zinc-iron crystals in the galvanizing bath. These are heavier than zinc and settle to the bottom of the galvanizing pot where they are periodically removed. Dross is the by-product of the galvanizing process which forms by reactions between zinc and loose particles of iron. Dross can exist at all depths of the pot, but normally sinks to the bottom.
Dross formation – It is the creation of a solid, impurity-rich by-product which floats on the surface of molten metal. It mainly occurs when metals react with oxygen and other furnace gases, producing oxidized impurities and non-metallic inclusions.
Dross inclusions – It is the dross which is carried out on to the work piece upon removal from the galvanizing pot.
Drossing – It is the process of removing dross build-up from the bottom of the pot.
Drum – It is a hollow, cylindrical component or vessel. Its exact function depends on the engineering discipline, ranging from a rotating mechanical rotor (e.g., in compressors and turbines) to a static container used for phase separation, chemical processing, or storing bulk cargo. Drum is also a cylindrical spool used to wind, store, or deploy cables, ropes, or hoses.
Drum diameter – It is the straight-line distance straight across the centre of a circular or cylindrical drum, measured from one inside or outside edge to the opposite side.
Drum drying – It is an industrial thermal process where a liquid, slurry, or paste is applied in a thin film onto the outer surface of a heated, rotating hollow metal cylinder. Moisture evaporates rapidly through conductive heat transfer from steam inside the drum, and a scraper blade removes the dried flakes or powder.
Drum ladle -It is an enclosed, horizontally-oriented cylindrical vessel lined with refractory material, used to transport and pour molten metal. Designed with a filling slot and a pouring spout, it typically features a bolted, removable cover which protects operators from splashing and reduces temperature loss.
Drum, magnetic – Magnetic drum normally refers to a specialized industrial separator used to automatically pull and separate ferrous (iron-based) materials from non-magnetic materials. It consists of a stationary internal magnetic core surrounded by a rotating outer shell made of non-magnetic stainless steel or manganese.
Drum mill – It is also known as a ball mill or tumbling mill. It is a mechanical grinding device which reduces materials into fine powders or granules. It utilizes a rotating horizontal cylinder loaded with feed material and heavy grinding media (such as steel balls, ceramic beads, or rods) which tumble and crush the material.
Drum mixing – It is a material-handling process which blends powders, granular solids, or viscous liquids inside a rotating cylindrical vessel (drum). As the drum turns, internal flights or the tumbling action of gravity cascade, lift, and uniformly distribute the ingredients.
Drum separator – It is a device consisting of a non-magnetic drum fitted with rare earth magnets which rotates over a moving stream of dry feed, allowing for the separation of ferro-magnetic and para-magnetic minerals from non-magnetic materials. It produces clean magnetic concentrate and improves separation efficiency through alternating north / south polarity of the magnets.
Drum shear – A drum type shear is normally used for product with a simple shape such as flats or rounds. The blades are mounted on a rotating cylinder (or drum) and are set at a ‘lead’ speed to minimize the ‘kinking’ of the bar.
Drum test – The test is based on Japanese industrial standards (JIS) standard JIS K2151. A 10 kg representative sample of +50 millimeters ‘square hole screen’ coke is placed in the specified tumbler drum and rotated for 30 revolutions, removed, screened and replaced in the drum and subjected to a further revolution of 150 revolutions. The drum contains lifters that raise the coke and allow it to fall so that it undergoes a large number of impacts with the drum walls. The indices reported are percentages of material remaining on +15 millimeters ‘square hole screen’ after 30 revolutions and the same after 150 revolutions. The larger is the value the higher is the coke strength.
Drum-type boiler – It is a type of boiler, specifically a water-tube boiler, characterized by the presence of a large, cylindrical drum which serves as a reservoir and separator for steam and water. This drum, also called a steam drum, is located at the top of the boiler and collects the steam generated in the water tubes, separating it from the water. The drum also acts as a reservoir, holding water for the circulation system and allowing for water treatment and blow-down.
Drum-type rotor – It is a component used in reaction turbines, characterized by its drum shape and typically constructed from low steam temperature-resistant materials like 1 % chromium to 2 % chromium steel, with options for corrosion resistance improvements through overlay welding or coating.
Dry abrasion – It is a wear process where solid material is scraped, scratched, or worn away by friction from hard particles or opposing surfaces without the presence of lubricating fluids or water. Testing this property evaluates a material’s weight loss and structural durability.
Dry abrasion testing method – It refers to a wear testing method conducted without the presence of water, where the material’s weight loss, wear track depth, and cross-sectional area are evaluated to determine its wear rate under frictional conditions.
Dry adhesion – It is a surface-attachment mechanism where two solid objects stick together through direct inter-molecular forces (mainly van der Waals forces) without utilizing liquid moisture, chemical glues, or tapes. It relies heavily on microscopic surface structures that maximize intimate contact area.
Dry air mass flow – It is the exact mass of dry air passing a point per unit of time. In HVAC (heating, ventilation, and air conditioning) and thermodynamics, it isolates the permanent gas portion of atmospheric air from water vapour. Engineers use it since the dry air mass stays constant during humidification or dehumidification.
Dry analysis – It refers to conducting theoretical, mathematical, or simulated evaluations of a system without conducting physical experiments or wet testing. It also specifically refers to evaluating the physical properties of ‘bone dry’ materials devoid of moisture (e.g., assessing particle size or density).
Dry and baked compression test – It is a test for determining the maximum compressive stress which a baked sand mixture is capable of developing.
Dry bag tooling – It refers to a setup for cold isostatic pressing (CIP) where the flexible rubber or elastomeric mould is permanently fixed directly inside the pressure vessel walls. The dry process relies on automated powder-filling and compression without directly submerging the mold in fluid. In contrast to traditional wet bag methods where a sealed mould is dipped entirely into a fluid-filled chamber, dry bag tooling is highly integrated.
Dry battery – It is also called dry cell. It is an electro-chemical power source which that uses an electrolyte in a solid, gel, or paste form rather than a free-flowing liquid. This immobilized design prevents spilling, allows operation in any orientation, and provides a compact, low-maintenance energy storage medium for portable systems.
Dry bearing – It is a sliding bearing consisting of a PTFE (poly-tetra-fluoro-ethylene, Teflon) and lead powder lining bonded to a metal backing.
Dry bond strength – It is the maximum load an adhesive or joint can withstand before separation, peeling, or shear failure, measured immediately after it has fully cured and dried. It establishes a baseline of structural integrity prior to any exposure to moisture or environmental stressors. Dry bond strength provides an important reference point used across multiple branches of engineering.
Dry bulb temperature – It is the ambient air temperature measured by a standard thermometer which is freely exposed to the air but shielded from radiation and moisture. It indicates the air’s sensible heat and is the true thermodynamic temperature normally reported in daily weather forecasts.
Dry cargo ship – It is a vessel designed to transport solid, non-liquid goods, either unpackaged in bulk or pre-packaged, without needing temperature-controlled or specialized fluid containment systems. These ships feature large structural holds, reinforced hatch covers, and specialized deck gear or material-handling interfaces.
Dry cell – It is a portable electro-chemical device which converts stored chemical energy into electrical energy. It uses an electrolyte immobilized as a moist paste or gel rather than a free-flowing liquid, making it leak-proof and operable in any position.
Dry cement – It typically refers to unhydrated cement powder stored in a dry state, or the dry process of manufacturing cement where raw materials are ground, mixed, and fed into a kiln as a dry powder rather than a liquid slurry.
Dry classifiers – Dry classifiers are based on the principle that separation by air fluidization. Air classification is a process of separating categories of materials by way of differences in their respective aerodynamic characteristics. The aerodynamic characteristic of a particular material is primarily a function of the size, geometry, and density of the particles. The process consists of the interaction of a moving stream of air, material particles, and the gravitational force within a confined volume. In the interaction, the drag force and the gravitational force are exerted in different directions upon the material particles. The result is that material particles that have a large drag-to weight ratio are suspended in the air stream, whereas components that have a small ratio tend to settle out of the air stream. The suspended fraction conventionally is referred to as the ‘air classified light fraction’ and the settled fraction is termed ‘air-classified heavy fraction’. The confined volume in which the separation takes place is called an ‘air classifier’.
Dry container – It is a standardized, six-sided intermodal freight container built to ISO (International Organization for Standardization) specifications. It safely transports general, non-liquid cargo which does not need temperature control.
Dry cooling tower – It is a closed-loop heat rejection device which cools hot process fluids or condenses steam using ambient air without evaporating any water. It works like a giant car radiator, passing fluid through finned tubes exposed to air flow to conserve water in arid regions.
Dry corrosion – It is the corrosion with gas as the only corrosive agent and without any aqueous phase on the surface of the metal.
Dry coupling – It is a type of shaft coupling (such as a disc or diaphragm coupling) which transmits torque between two rotating shafts without any sliding or rubbing metal parts. In fluid handling and piping, a dry coupling (normally called a dry break or dry disconnect coupling) is a specialized valve fitting used to connect hoses to pipes.
Dry-cum-wet processing – In dry-cum-wet process, fines fraction (-10 mm) generated after dry processing of iron ore is further processed in mechanical classifiers, and hydro-cyclones etc. to get -10 mm to + 0.15 mm size product which constitutes the feed material for the sintering process. The classifier / hydro-cyclone overflow i.e., -0.15 mm (100 mesh) size product constitutes the slime and dumped into the tailing pond.
Dry cutting – It is the machining or sawing of materials without using liquid coolants or lubricants. It relies on specialized heat-resistant tools and air cooling instead of oils or water. This green technology cuts fluid costs and protects the environment, but it creates higher tool temperatures.
Dry cyaniding – It is an obsolete term. The present term is carbo-nitriding. It is a case-hardening process in which a suitable ferrous material is heated above the lower transformation temperature in a gaseous atmosphere of such composition as to cause simultaneous absorption of carbon and nitrogen by the surface and, by diffusion, create a concentration gradient. The heat-treating process is completed by cooling at a rate which produces the desired properties in the work-piece.
Dry density – It is the mass of solid soil particles divided by the total volume of the soil sample, with all water removed. It measures how tightly solid particles pack together without water weight. Engineers use it to judge soil compaction quality, strength, and load-bearing safety.
Dry drawing – It is a cold-working process where metal stock is pulled through a die to reduce its diameter and increase its length. The defining characteristic of this method is the use of dry lubricants, such as powdered metallic soaps, rather than liquid oils.
Dry drawing continuous machine – It is an industrial machine which reduces the diameter of metal wire or rods by pulling them through multiple, progressively smaller dies using dry powdered lubricants and motor-driven capstans to maintain continuous, uninterrupted production flow.
Dry environment – It is a controlled space or operational setting where moisture, humidity, and liquid water are kept at extremely low, specific levels to prevent material degradation, corrosion, or chemical reactions.
Dryer, core – It is also spelled as drier, core. Core dryer is also called core baking oven. It is a high-efficiency industrial oven used to cure, bake, or dry the cores before molten metal is poured around them.
Dryer, dielectric – It is also called drier, dielectric. Core dielectric dryer (frequently using radio frequency or micro-wave technology) uses high-frequency electro-magnetic waves to rapidly heat and vapourize moisture trapped inside non-conductive materials. Instead of relying on slow surface heat, the electro-magnetic field creates molecular friction to dry the material uniformly from the inside out.
Dry etching – In metallography, it is the development of micro-structure under the influence of gases.
Dry expansion – It is frequently called direct expansion. It refers to a refrigeration system design where an expansion valve meters liquid refrigerant into an evaporator coil. The refrigerant absorbs heat and completely vaporizes into a dry gas before exiting, protecting the compressor from liquid damage.
Dry feed system – It is an automated or mechanical arrangement used to store, meter, and transport solid granular, powdered, or dry bulk materials into a main process line or reactor without adding liquids or creating slurries.
Dry-film lubrication – It is the lubrication which involves the application of a thin film of solid lubricant to the surface or surfaces to be lubricated.
Dry fining – It is also called dry fine-grinding. It is the mechanical finishing process of passing metal against a dry, abrasive-coated wheel or belt without the use of lubricants. It is the second step in a four-stage metal polishing process consisting of roughing, dry fining, greasing, and colouring.
Dry flue gas desulphurization – It is a pollution control process which removes sulphur di-oxide (SO2) from industrial exhaust gases by injecting dry alkaline sorbents directly into the gas stream. It creates a solid waste by-product without generating liquid waste-water.
Dry friction – It is the friction which occurs between two bodies in the absence of lubrication. However, this term is inaccurate since it historically implies that there is no intentionally applied lubrication, when in fact, solid lubrication conditions can be considered ‘dry’. Hence, this term is not to be used.
Dry fuel store – It is a building specifically designed for the storage in dry conditions of used nuclear fuel from the operation of a nuclear power plant.
Dry galvanizing – It is the dipping of steel in an aqueous zinc ammonium chloride solution and then thoroughly drying before immersing in the molten zinc bath.
Dry gas seal – It is a specialized mechanical face seal used in high-speed rotating equipment like centrifugal compressors. It uses a thin layer of pressurized gas between a stationary ring and a rotating ring to stop process gas leaks. This contact-free design cuts friction and removes the need for oil.
Dry gas seal (DGS) system – it involves designing non-contacting mechanical face seal arrangements and gas conditioning panels for high-speed centrifugal compressors. Micro-machined grooves on the rotating ring generate a dynamic lifting force, maintaining a stable 3 micro-meters to 10-micro-meters gas film gap which eliminates face friction and wear during operation.
Dry glycol – It is also called lean glycol. It is a high-purity liquid desiccant, typically tri-ethylene glycol (TEG), which has a very low water content. It is pumped into the top of a contactor tower to absorb water vapour from wet natural gas streams.
Dry grinding – It is a material-processing or abrasive machining method performed without any liquid coolant, water, or solvent. It relies entirely on direct mechanical contact, friction, and air or inert gas convection to manage debris and reduce work-piece size.
Dry ice – It is the solid state of carbon di-oxide (CO2) maintained at an ultra-low temperature of -78.5 deg C under atmospheric pressure. It is valued since it undergoes sublimation, transitioning directly from solid to gas without passing through a liquid phase, leaving zero moisture residue.
Dry ice blasting – It is a non-abrasive, non-conductive industrial cleaning process which accelerates solid carbon di-oxide (CO2) pellets through a high-velocity compressed air stream to strip surface contaminants. Upon impact, the media instantly sublimates, turning from a solid directly into a gas without leaving secondary chemical waste or moisture.
Drying – It is a mass-transfer process which removes liquid (normally water) from a solid, semi-solid, or liquid matrix by evaporation or sublimation. It uses thermal energy to vapourize the moisture and a gas or vacuum to carry the vapour away.
Drying cracks – These are irregular cracks in dry, unfired porcelain enamel caused by uneven or too rapid drying of the ware. The cracks may or may not heal over during the firing operation.
Drying cycle – It is a controlled thermal and mass-transfer process used to remove moisture or liquid solvents from a solid, liquid, or gas material. It combines heat input and vapour removal through phases like heating, mass diffusion, and cool-down to achieve a specific target moisture content.
Drying cylinder – It is used for thermal drying. It is a steam-heated rotating metal drum used in continuous manufacturing to evaporate and remove residual moisture from web materials like paper, textiles, or plastic films through conductive contact heat transfer.
Drying machine – It is a mechanical thermal device used to reduce or remove surface moisture from metal concentrates, mineral ores, coal, or filter cakes prior to smelting, roasting, or further processing.
Drying, material – Drying of material is the process of removing water or other liquid from a solid, semi-solid, or liquid substance. This is normally done by applying heat to turn the moisture into a vapor, which is then carried away by air or a vacuum.
Drying method – It is a technique used to remove moisture from materials, typically through the application of heat, which drives water from the substance and allows for the measurement of weight loss to determine moisture content. Several heating methods, such as air ovens, vacuum ovens, infrared drying, and microwave drying, can be used, each affecting the efficiency and accuracy of the drying process.
Drying oil – It is a water-insoluble liquid, normally obtained from a plant source, which reacts with oxygen (from the air) to form a cross-linked polymeric film.
Drying operation – It is a mass transfer process which removes a small quantity of water or liquid from a solid or semi-solid material by turning it into vapour using heat. It is frequently the final step before packing or selling a product.
Drying rate – It is the speed at which moisture (water or solvent) leaves a wet material. It is measured as the mass of moisture removed per unit of surface area per unit of time. This process relies on both heat transfer (providing energy to evaporate liquid) and mass transfer (carrying the vapour away).
Dry ingredient – It is a solid, particulate material, such as a powder, granule, or crystal, processed without free-flowing liquid. These materials require specialized handling, precise gravimetric or volumetric dosing, and controlled dry blending to achieve complete homogeneity in manufacturing systems.
Drying shrinkage – It is the contraction or reduction in volume and length of a hardened material, very frequently concrete, caused by the evaporation of capillary water and moisture loss to the surrounding environment.
Drying technologies – These technologies refer to mass transfer processes which remove water or solvents through evaporation from solids, liquids, or semi-solids. The main goal is to prevent bacterial growth, prolong shelf life, and stabilize products for downstream processing or storage. Several methods span different industries. They can be mainly categorized based on their mechanism of heat and mass transfer.
Dry laid – It mainly refers to a manufacturing process for making non-woven fabrics where dry fibres are manipulated and formed into a sheet using mechanical carding or air streams before being bonded together. The term can also describe placing stones, bricks, or tiles without using wet mortar or binding agents.
Dry laminate – It is a laminate containing insufficient resin for complete bonding of the reinforcement.
Dry lay-up – It is the construction of a laminate by the layering of pre-impregnated reinforcement (partly cured resin) in a female mould or on a male mould, normally followed by bag moulding or autoclave moulding.
Dry low emission – It is also known as dry low NOx (DLN). It is a gas turbine combustion technology designed to minimize nitrogen oxides (NOx) pollutants without injecting water or steam into the combustor. It achieves low emission targets by utilizing advanced lean-premixed combustion principles.
Dry low NOx – It is a gas turbine combustion technology which cuts nitrogen oxides (NOx) pollution without injecting water or steam. It uses a lean, pre-mixed air-and-fuel design to lower peak flame temperatures and stop NOx from forming.
Dry lube – It is dry-film moly-di-sulphide applied as a coating to sliding or rotating parts to reduce frictional drag. After application, the film is baked in an oven at high temperature.
Dry lubricant – It is a solid which is used as a powder or thin film on a surface to provide protection from damage during relative movement, and to reduce friction and wear. However, it has been suggested that this term is not to be used as a synonym for solid lubricant since some solid lubricants perform better in the presence of moisture (e.g., graphite). Instead, it has to refer to lubricants which function in low-moisture environments.
Dry machining – It is a manufacturing process which cuts, turns, or drills metals without using liquid coolants or traditional cutting oils. Instead of fluids, it relies on advanced tool coatings, specialized tool designs, and compressed air to manage heat and clear chips.
Dry mass – It refers to the mass of an ore, metal, or chemical sample after all moisture and water content has been completely removed. It is calculated as ‘dry mass = total mass – moisture mass’. It is the mass of a sample after all moisture has been removed, typically measured following a drying process in a vacuum desiccator or with anhydrous materials.
Dry matter – It is the remaining solid mass of a substance after complete moisture and water removal. It serves as a base-line parameter to calculate solid concentrations, manage mass balances, and control quality in fields like environmental, and chemical engineering.
Dry micro-EDM – It is a variant of micro-electrical discharge machining (EDM) which utilizes oxygen or air as the di-electric medium, reducing pollution and waste management costs associated with liquid di-electrics in the machining process.
Dry micro machining – It is a precision manufacturing process used to create miniature components (typically 1 micro-meter to 500 micro-meters in size) without using liquid coolants or cutting fluids. It relies instead on gas mediums like air or plasma to remove material, reduce ecological impact, and prevent thermal distortion.
Dry milling – It is a mechanical size-reduction process where solid raw materials are crushed, ground, or broken into smaller particles without using liquids, water, or chemical solvents. Size reduction happens through particle-on-particle impacts or contact with grinding tools.
Dry mix – It is also called dry vibratable refractory. It is unshaped refractory which is specially designed to be placed in the dry state by vibration or ramming. During placing a dry mix reaches maximum compaction and it becomes possible to remove the former either before or after heating. The material can include a temporary bond but it eventually has a ceramic bond.
Dry objective – It is a microscope objective which is designed for use without liquid between the cover glass and the objective or, in the case of metallurgical objectives, in the space between objective and sample.
Dry oxidation – It typically refers to thermal oxidation in semi-conductor manufacturing where a silicon wafer is heated at high temperatures (800 deg C to 1,200 deg C) in pure oxygen gas (O2) to grow a thin, dense, and high-quality layer of silicon di-oxide (SiO2).
Dry paint film – It is the hardened, solid layer of coating left on a surface after the liquid paint has been applied and all solvents or water have completely evaporated and cured.
Dry pan – It refers to an industrial, heavy-duty grinding machine equipped with massive revolving rollers (mullers) which crush and pulverize hard materials, such as clay, ores, and ceramics, over a stationary or revolving metal floor.
Dry permeability – It is the property of a moulded mass of sand, bonded or unbonded, dried at around 100 deg C to 110 deg C, and cooled to room temperature, which allows the transfer of gases resulting during the pouring of molten metal into a mould. Dry permeability is the capacity of a porous, solid material, such as foundry sand, concrete, or soil, to permit fluids (like gases or water vapour) to pass through its interconnecting pores after it has been completely dried.
Dry pressing – It is a manufacturing process used for ceramics and powder metallurgy, where free-flowing granulated powder containing minimal moisture (normally less than 7 %) is compressed inside a rigid steel die under high mechanical or hydraulic pressure to form a solid, shaped component.
Dry pressing process – It is a manufacturing method where free-flowing granulated powder, mixed with a tiny quantity of binder and low moisture (less than 7 %), is compacted inside a rigid steel die using high uniaxial pressure (20 mega-pascals to 500 mega-pascals) to form a solid, shaped object called a green body. It is a simple and cost-effective method, and has been widely used to make parts thicker than 0.5 millimeters. Pressing methods can include cold, warm, hot, cold-isostatic or hot-isostatic pressing. In refractory brick production, plasticity of refractory powder mix is used in the dry-press process. A minimum of water is added, the material is placed in steel moulds, and pressures up to 500 mega-pascals are applied. The dry-press process, using steel moulds, gives a smooth texture.
Dry process – It refers to a manufacturing or preparation method which operates without liquid solvents or where raw materials are processed in a dry, solid state (under 1 % moisture). It contrasts with wet processes by eliminating water evaporation stages, which saves substantial thermal energy.
Dry process enameling – It is a porcelain enameling process in which the metal article is heated to a temperature above the maturing temperature of the coating, normally 870 deg C to 955 deg C. The coating materials are applied to the hot metal as a dry powder and fired.
Dry processing – In case of iron ore, dry processing is done for meeting the size requirements and involve multi-stage crushing and screening to meet the size requirements needed by different iron smelting processes.
Dry quenching – In the dry quenching process, the red-hot coke is cooled by mixed gas (mainly consisting of nitrogen) circulating in an enclosed system, thereby preventing the release of airborne coke dust. The thermal energy of the red-hot coke, which is lost in the conventional wet quenching, is collected and reused as steam.
Dry ramming mixes – These are based on high purity magnesite and a sintering aid are useful in steel making. magnesite ramming mixes of exceptional purity and stability are used primarily as lining materials for coreless type induction furnaces. Magnesite chrome fused grain ramming mixes provide exceptional density and strength.
Dry reforming – It is a catalytic chemical process which converts green-house gases, specifically methane (CH4) and carbon di-oxide (CO2), into synthesis gas, or syngas, which is a mixture of hydrogen (H2) and carbon mono-oxide (CO).
Dry reforming of bio-gas – It is a chemical process which converts methane and carbon di-oxide, the two main parts of bio-gas, into synthesis gas (syngas), which is a mix of hydrogen and carbon mono-oxide. This high-heat reaction uses no water, turning harmful green-house gases into useful fuel.
Dry reforming of methane – It is a chemical process which converts two green-house gases, methane (CH4) and carbon di-oxide (CO2), into synthesis gas (syngas), a mixture of hydrogen (H2) and carbon mono-oxide (CO).
Dry-running – In seals, it means running without liquid present at the seal surface.
Dry sand – It refers to moulding sand (typically silica sand and clay) which has been baked in an oven to remove almost all of its moisture before the molten metal is poured. Unlike ‘green sand’, which contains moisture to hold its shape, dry sand is moisture-free, which provides several distinct advantages in metal casting.
Dry sand casting – It is the process in which the sand moulds are dried at above 100 deg C before use.
Dry sand core – It is a pre-formed, hardened sand insert placed inside a casting mould to create hollow cavities, undercuts, or complex internal passages. Unlike standard mould sand, dry sand is mixed with binders (such as resins or oils) and baked, gassed, or air-set to achieve high structural strength before being placed into the mould.
Dry sand mould – It is a casting mould made of sand and then dried at 100 deg C or above before being used. It is a foundry sand mould made by baking or heating a green sand mould (a mixture of silica sand, clay, and moisture) to completely evaporate all its water content. This baking process considerably increases the mould’s strength, rigidity, and thermal stability to withstand heavy, high-temperature molten metal pours.
Dry sand moulding – Dry sand moulding processes make dry sand moulds by several different processes. Sand mixed with binders which cure by baking is one form of making dry sand mould. Other more common dry sand moulding techniques use sand with binders which can be cured by chemical, or catalytic, reaction induced by mixing.
Dry-sand rubber wheel test – In wear testing, it is a term used to describe a standard abrasive wear testing method in which a stream of dry quartz sand is passed between a rotating rubber wheel and a stationary test coupon which is held against it under specified normal force. It is a standard laboratory method used to measure a material’s resistance to scratching and gouging abrasion. It simulates low-stress, three-body abrasive wear. The test evaluates how well metals, alloys, and wear-resistant coatings (e.g., hard-facing alloys, thermal spray coatings) hold up against hard, abrasive particles. It is termed ‘three-body’ abrasion since the abrasive grit is free to roll and slide between the metal coupon and the rotating rubber wheel, rather than being fixed to a surface.
Dry saturated steam – It is vapour at the exact boiling temperature for a given pressure, containing zero liquid water droplets in suspension. Its dryness fraction equals unity (x = 1), meaning it delivers maximum latent heat for efficient industrial heating without causing moisture-related erosion.
Dry screening – It refers to the process of removing impurities and unwanted materials from the ore through the use of different screening techniques. This method does not need the use of water, unlike wet screening processes which rely on water to separate particles.
Dry screw compressor – It is a positive displacement rotary machine which uses two intermeshing helical rotors to compress gas. It is called ‘dry’ since no oil or fluid is injected into the compression chamber, ensuring the output gas remains 100 % oil-free.
Dry scrubbers – These scrubbers offer an alternative to wet scrubbers, which need an additional waste-water disposal system. These scrubbers do not use wet products to treat the exhaust gas. Instead, these systems use a dry reagent called a sorbent to either neutralize or separate the acids from the gas. As in wet scrubber systems, dry scrubbers need to maximize surface area contact between the sorbent and the gas to remove as much acid from the exhaust as possible. Filters in the system filter out particulate matter the sorbent cannot impact. After the sorbent passes through the gas, it becomes a hazardous material that requires special disposal.
Dry scrubbing system – It is a type of pollution control device which removes pollutants from exhaust gases using solid sorbent materials, rather than a liquid medium. These systems are normally used to treat acid gases like sulphur di-oxide (SO2) and hydrogen chloride (HCl), converting them into solid or less harmful substances.
Dry season – It is a recurring period of low precipitation where evaporation and transpiration exceed rainfall. This creates a negative water balance, lowering ground-water tables, reducing surface run-off, and increasing structural and geo-technical demands on water resource management.
Dry sheet – It is because of failure of the lubricant to meet the agreed-upon minimum limit measured in weight per unit area.
Dry slag granulation process – In this process, it is essentially to atomize the liquid slag and then to cool the particles rapidly so as to produce a glassy slag. The atomization is done using a rotary cup air blast atomizer. The particles cool as they travel through the air and are then cooled further in a fluidized bed. Both of these processes provide the rapid cooling necessary for the formation of glassy slag product. The fluidized bed is a convenient method of containing the slag particles as it prevents the agglomeration of hot particles in addition to providing rapid cooling.
Dry slag pit – It is a pit where liquid slag is diverted for solidifying in case of some problem in the slag granulation plant.
Dry sliding wear – It is the sliding wear in which there is no intentional lubricant or moisture introduced into the contact area.
Dry sorbent injection – It is a process used to remove acid gases like sulphur di-oxide (SO2) and hydrogen chloride (HCl) from flue gas streams by injecting a dry, powdered sorbent (like hydrated lime or sodium bi-carbonate) into the gas stream. This process, typically used in industrial facilities like power plants, captures the acid gases through a reaction with the sorbent, reducing emissions.
Dry steam – It is the steam which contains 100 % of water vapour in the gas phase. Steam which contains no water molecules, is referred to as dry steam, or dry saturated steam. Steam tables normally list data based on dry saturated steam values. Dry saturated steam is difficult to produce in a boiler since some water droplets are almost always present. Boiler systems are optimized for generating saturated steam. The actual level achieved is measured as the ‘dryness fraction’. If the water content of the steam is 4 % by mass, then the steam is said to be 96 % dry and has a dryness fraction of 0.96.
Dry steam system – It utilizes saturated or slightly super-heated vapour containing little to no suspended liquid water droplets (a dryness fraction close to 1 or 100 %). It optimizes heat transfer efficiency, prevents thermal erosion in turbines, and minimizes pipe corrosion.
Dry strength – In casting, it is the maximum strength of a moulded sand sample which has been dried thoroughly at 100 deg C to 110 deg C and cooled to room temperature. It is also known as dry bond strength. In refractories, dry strength is the mechanical strength of a shaped and dried, but unfired refractory.
Dry storage – It is the storage of spent fuel in air or an inert gas rather than water.
Dry sump – It is an engine lubrication design which stores motor oil in a separate external tank instead of a pan at the base of the engine. It uses multiple fluid pumps to scavenge oil from the crankcase continuously and pump it under high pressure to moving parts.
Dry surface – It is a foil surface which is substantially free from oily film and suitable for lacquering, printing, or coating with water-dispersed adhesives.
Dry transport – It mainly refers to the method of moving heavy structures, such as offshore oil platforms or ship modules, by loading them completely out of the water onto a heavy-lift vessel or cargo barge, rather than towing them while floating (wet transport).In broader industrial contexts, it also describes moving solid, non-liquid materials without fluid suspension.
Dry unit weight – It is the weight of a soil sample per unit volume when all moisture is removed, typically expressed in tons per cubic meter. It indicates the density of soil materials, with laboratory tests showing that the dry unit weight of several peat samples is below 0.8 tons per cubic meter.
Drywall – It is a pre-manufactured panel made of a gypsum plaster core sandwiched between heavy paper or fibre-glass facings. It is fastened to wood or metal framing studs to build interior walls and ceilings without wet mortar or drying time.
Dry washing – It refers to water-free purification or surface treatment processes. It removes contaminants or creates distressed textures using mechanical forces, gases, or solid adsorption media instead of liquid water.
Dry welding – It is normally known as hyperbaric welding. It is a process performed underwater inside a specially built, pressurized enclosure or chamber from which water is removed. This controlled gas environment prevents the rapid cooling and cracking risks associated with direct water contact.
Dry winding – It is a term used to describe filament winding using pre-impregnated roving, as differentiated from wet winding, where unimpregnated roving is pulled through a resin bath just before being wound onto a mandrel.
D-spacing – It is the perpendicular distance between adjacent, parallel planes of atoms in a crystal lattice. It is normally measured in angstroms or nano-meters (nm) and helps identify material structure and composition.
Duality principle – It states that certain pairs of physical systems, equations, or concepts share an identical mathematical structure. Swapping specific fundamental variables (like voltage for current, or series for parallel) transforms one valid system description into another valid system description.
Dual-alloy processing – It is a technique used to combine two different metal alloys into a single, continuous component. This allows engineers to place distinct materials exactly where their unique properties are most needed, such as combining a wear-resistant alloy on the outside with a light-weight, strong alloy on the inside.
Dual-alloy turbine disk – It is also called dual-alloy turbine wheel. It is a hybrid aerospace component engineered by joining two distinct metals into a single rotating part. It optimizes the rotor by placing different alloys in the low-temperature core (bore) and the high-temperature outer edge (rim) to survive extreme jet engine environments.
Dual-axis tracking – It is a mechanical and control system engineering method which rotates a device—such as a photo-voltaic panel or telescope, on two independent axes. This dual movement keeps the surface completely perpendicular to the sun at all times, boosting energy capture by up to 40 % compared to fixed mounts.
Dual-chamber fluid filter – It is an industrial filtration system with two parallel filter chambers connected by a change-over valve. It allows one chamber to filter fluid while the other stays on standby, enabling safe cleaning or media replacement without shutting down the system.
Dual code – It is the set of all vectors which are orthogonal (have an inner product of zero) to every codeword in a given linear code C. If the original code has length ‘n’ and dimension ‘k’, its dual code has length ‘n’ and dimension ‘n – k’.
Dual control management – It is a security and governance principle which needs two or more authorized individuals to independently approve a sensitive task before it can be executed. It prevents fraud and accidental errors by ensuring no single person holds the authority to complete high-risk operations.
Dual controls – These controls refer to redundant or mirroring control stations which allow two operators to control a system simultaneously.
Dual control volume – It is a secondary, non-overlapping control cell constructed around grid nodes by connecting element centroids, face centroids, and edge mid-points in a median-dual mesh scheme. It pairs with a primary mesh to solve conservation equations.
Dual damascene – It is a semi-conductor manufacturing technique used to create multi-level metal interconnects. It etches patterns for both vertical contact holes (vias) and horizontal wires (trenches) into a non-conductive di-electric layer, filling both structures with copper in a single electroplating step.
Dual filter – It typically refers to a dual media filter (two layers of filtering material like anthracite and sand for water treatment), a duplex / double fluid filter (two parallel housings with a valve for continuous flow maintenance), or a dual estimation filter (two recursive algorithms like extended Kalman filters separating states and parameters).
Dual frame – It can refer to a dual structural system in civil engineering (combining shear walls and moment frames for lateral loads). It is also a secondary set of vectors used to reconstruct elements in a Hilbert space from their frame coefficients, acting similarly to a dual basis. In statistics and survey research, it refers to using two overlapping sample lists to reach a target population.
Dual-fuel burner – It is a device capable of combusting more than one type of commercial fuel. It allows for the use of different fuel sources, frequently including a primary, less costly fuel, and a secondary, more reliable fuel.
Dual-fuel combustion – It is a process where an internal combustion engine burns two different fuels with distinct reactivities at the same time. Typically, a primary gaseous or alternative fuel is mixed with air, and a small quantity of liquid pilot fuel (like diesel) ignites to start the reaction.
Dual-fuel engine – It is an internal combustion engine which burns two different fuels at the same time. It typically uses a gaseous primary fuel like natural gas mixed with air, ignited by a small pilot injection of a liquid fuel like diesel.
Dual fuel mode – It is an operation method for internal combustion engines where two different fuels, typically a primary gaseous fuel (like natural gas, biogas, or hydrogen) and a liquid pilot fuel (like diesel), are burned at the same time inside the combustion chamber.
Dual fuel vehicle – It is a motor vehicle with two separate storage systems which burns two different fuels simultaneously in its internal combustion engine, very frequently combining a liquid fuel like diesel with a gaseous alternative fuel like compressed natural gas (CNG) or liquefied petroleum gas (LPG).
Dual-ion battery – It is a rechargeable energy storage device where both cations and anions from the electrolyte actively participate in reversible charge and discharge reactions. Unlike standard single-ion ‘rocking-chair’ batteries, a dual-ion battery (DIB) uses a dual-intercalation salt-splitting mechanism at both electrodes simultaneously.
Dual matrix – It mainly refers to a matrix whose elements are dual numbers (A + e Ao, where e-square = 0 and ‘e’ is not 0), used in kinematics and geometry. In linear algebra and statistics, it can also describe a transpose or alternative structural pairing like ‘X’ to the power ‘T’ x ‘X’ against ‘X’ x ‘X’ to the power ‘T’.
Dual measurement – It refers to using two distinct metrics, units, or evaluation criteria simultaneously to assess, track, or price an item or system. It ensures accuracy when a single unit cannot fully capture or price the total scope of work, inventory, or physical data.
Dual media filter – It is a water-treatment system which uses two distinct layers of graded media, typically coarse anthracite coal on top and finer sand below, to remove suspended solids, turbidity, and organic particles through depth filtration.
Dual media filtration – It is a water treatment process which uses two distinct layers of media, typically coarse anthracite coal on top and finer sand below, to remove suspended solids, turbidity, and impurities through progressive in-depth filtration.
Dual-metal centrifugal casting – It is the centrifugal castings produced by pouring a different metal into the rotating mould after the first metal poured has solidified.
Dual-micro-structure processing – It is a specialized technique used to create two distinct microstructural zones within a single component. By combining specific heat treatments and localized thermal control, engineers produce areas optimized for different mechanical demands, such as a coarse-grained, creep-resistant core and a fine-grained, fatigue-resistant surface. The technique is widely applied to advanced alloys.
Dual-micro-structure thermo-mechanical processing – It is an advanced metallurgical manufacturing method which integrates plastic deformation and localized thermal treatments to produce a single component with two distinct, spatially separated micro-structures. This allows engineers to optimize different zones of a part for entirely different mechanical demands. This methodology uses highly specialized thermal management during forging or heat treatment to vary the micro-structure across a single part.
Dual-mode sorption model – It is a frame-work used to describe how gases and vapours dissolve in glassy polymers. It combines ordinary dissolution (following Henry’s law) with hole-filling site adsorption (following Langmuir’s model) to account for fixed micro-voids trapped inside rigid polymer networks.
Dual-phase (DP) steels – The term dual phase steels, or DP steels, refers to a class of high strength steels which is composed of two phases namely a purely ferrite matrix and a dispersed second phase of martensite (5 % to 30 %). In addition to martensite, small quantities of bainite and residual austenite can exist. The steel behaves like composite materials where the ferrite matrix assures high cold formability, and the martensite is the strengthening element. The correct proportion between the two phases allows a continuous yield point, low yielding stress, and a high elongation value, a smooth flow stress curve with a high strain hardening coefficient, and better plasticity and formability. The micro-structure of steel gives a good combination of high tensile strength, low yield-to-tensile strength ratio and very high initial work hardening rate with good elongation values. Dual phase is very formable, providing more flexibility in part design. The strength of the formed part is much higher than high strength low alloy steel, especially at very low strain. The high initial work hardening rate and high tensile strength give dual phase steel a very high capacity to absorb energy, making these steels suitable for use in structural and reinforcement applications.
Dual peening – It is also called double shot peening. It is an advanced metal-working process where a component undergoes two distinct stages of shot peening. Typically, the first pass uses high-intensity media to drive compressive stress deep into the material, and a second pass uses smaller, harder media to smooth the surface and maximize near-surface hardness.
Dual ramp configuration– It refers to a surface or system featuring two consecutive inclined planes or gradient stages. Depending on the discipline, it is used to manage mechanical force transmission, control shock waves in high-speed fluid dynamics, or generate dual-polarity electrical signals.
Dual scheme – It refers to an architecture, control method, or modeling approach which utilizes two complementary, interacting, or parallel mechanisms to achieve stability, optimization, redundancy, or conversion between two states.
Dual seal – It is also called double mechanical seal. It uses two sets of sealing faces arranged in series along a rotating shaft. A clean barrier or buffer fluid fills the space between them to lubricate the faces, cool the system, and prevent toxic or hazardous process fluids from leaking into the atmosphere.
Dual seat – It is a combination of one uni-directional seat and one bi-directional seat installed in the same valve body. The directions of both seats shall be specified on a separate identification plate. This design provides two sealing barriers in one direction and one sealing barrier in the opposite direction.
Dual seat (both seats bi-directional valve) – It is a valve with two seats, each sealing in both directions.
Dual seat (one seat uni-directional and one seat bi-directional valve) – It is a valve with two seats, one sealing in one direction and the other in either direction.
Dual shot peening – It is frequently called double shot peening. It is a specialized surface improvement process where a metal component undergoes two consecutive shot-peening treatments to considerably improve its fatigue life, strength, and wear resistance. It works by bombarding a metal surface with small spherical media (shots) to create plastic deformation. This process induces beneficial compressive residual stresses in the outer layer of the material, making the component highly resistant to metal fatigue and stress corrosion cracking.
Dual slope converter – It is an analog-to-digital converter (ADC) which measures an unknown input voltage by integrating it for a fixed time period, then integrating a known reference voltage in reverse until the signal returns to zero.
Dual system shears – These shears are normally used as cooling bed shears. They are equipped with two cutting systems namely (i) crank rotary system, and (ii) crank lever system. The crank lever system is mainly used for cutting sections. The shear is moveable perpendicular to the rolling direction in order to bring the system being used in line of rolling.
Dual vector – It is a linear functional which maps a standard vector to a scalar value, while a dual surface typically arises in dual number algebra and spatial kinematics to model rigid-body motions, screw axes, and complex surface profiles.
Dual wedge surface – It refers to a symmetrical double-sloped geometry, formed by two inclined planes meeting at a central crest or edge, used to convert an axial input force into high lateral, transverse, or splitting forces.
Dubinin-Radushkevich equation – It is a semi-empirical adsorption model used to evaluate pore-filling mechanisms in micro-porous solids like activated carbons and zeolites. It relates adsorption capacity to Polanyi potential energy, helping calculate maximum adsorption limits and mean adsorption energy.
Duck-bill pliers – It is a type of plier with broad, flat, and often thin jaws which resemble a duck’s bill.
Duck-bill valve – It is a check valve, normally manufactured from rubber or synthetic elastomer, and has two or more flaps, normally shaped like the beak of a duck. It is normally used to prevent contamination because of the backflow. One end of the valve is stretched over the outlet of a supply line, conforming itself to the shape of the line, normally round. The other end, the duckbill, retains its natural flattened shape. When a fluid is pumped through the supply line and hence the duckbill, the flattened end opens to permit the pressurized fluid to pass. When pressure is removed, however, the duckbill end returns to its flattened shape, preventing backflow.
Duck’s bill tool – It is a specialized hand-held finishing tool used in manual metal spinning (lathe-based sheet metal forming).
Duct – Duct is a tube, canal, pipe, or conduit by which a fluid, air, gas, or other substance is conducted or conveyed.
Duct cell – It refers to a discrete incremental volume or single computational flow passage within a multi-channel fluid transport system, fuel cell stack, or heat exchanger used for modelling mass transfer, pressure drop, and velocity profiles.
Duct cross – It is a four-way fitting. It is a junction component which connects four duct segments in a planar intersection. It typically features one main run or inlet splitting and intersecting into opposing or perpendicular branch lines to distribute or divide airflow across a complex network.
Duct diameter – It is the inner width of a round ventilation pipe. For non-circular or rectangular ducts, engineers use equivalent diameter (De) or hydraulic diameter (Dh). This value represents a circular size which creates the same friction loss and air flow rate.
Ducted fan – It is an axial-flow propulsion system or pump where a rotating impeller or fan blade is closely fitted inside a cylindrical shroud or duct. The housing controls air-flow velocity, raises pressure, and prevents tip vortices to boost thrust and efficiency.
Ducted propeller – It is a rotating screw blade surrounded by a non-rotating aero-dynamic or hydro-dynamic ring shroud. Both the enclosed blade and the outer duct generate lift or thrust. The set-up increases low-speed efficiency, stops tip vortex losses, and protects the blades from physical impacts.
Duct form – It refers to the specific geometric cross-section and structural profile of a conduit used to direct and transport fluids, air, or gases. The chosen form (such as round, rectangular, or oval) dictates fluid dynamics, pressure loss, space efficiency, and manufacturing cost.
Duct geometry – It is the physical shape and size of a conduit’s cross-section and layout. It dictates how fluids or gases move, how friction and pressure change, and how heat transfers through the system.
Ductile – A material is ductile when it is capable of being plastically deformed before fracturing.
Ductile behaviour – It is the ability of a material (like a metal) to undergo substantial permanent / plastic deformation under tensile stress without rupturing. It is the mechanical property which allows materials to be stretched into long, thin wires or bent into complex shapes.
Ductile cast iron – It is a cast iron which has been treated while molten with an element such as magnesium or cerium to induce the formation of free graphite as nodules or spherulites, which imparts a measurable degree of ductility to the cast metal. It is also known as nodular cast iron, spherulitic graphite cast iron, and spheroidal graphite (SG) iron.
Ductile crack growth – It is the slow, stable extension of a crack in a metal or plastic. It happens alongside heavy plastic bending and stretching near the sharp tip of the crack.
Ductile crack propagation – It is the slow crack propagation which is accompanied by noticeable plastic deformation and needs energy to be supplied from outside the body.
Ductile erosion behaviour It is the erosion behaviour having characteristic properties (i.e., considerable plastic deformation) which can be associated with ductile fracture of the exposed solid surface. A characteristic ripple pattern forms on the exposed surface at low values of angle of attack.
Ductile failure – It is a structural break-down mode where a material undergoes extensive plastic (permanent) deformation and energy absorption before a complete fracture occurs. It is common in metals like mild steel, aluminum, and copper under tensile loads.
Ductile fracture – It is the fracture characterized by tearing of metal accompanied by appreciable gross plastic deformation and expenditure of considerable energy.
Ductile fracture criterion – It is a mathematical model used to predict how much a metal can be deformed before microscopic cracks begin to form and grow. These limits are critical for optimizing metal forming processes like rolling, forging, and stamping to prevent material failure.
Ductile iron – Ductile cast iron also known as nodular cast iron, spheroidal graphite iron or SG iron, and spherulitic cast iron. As the name ductile iron suggests this grade of cast iron has a degree of ductility. The main characteristic of this material is the structure of the graphite. Ductile iron is a family of cast graphitic irons which possess high strength, ductility and resistance to shock. Annealed cast ductile iron can be bent, twisted or deformed without fracturing. Its strength, toughness and ductility duplicate many grades of steel and far exceed those of standard gray irons. Yet it possesses the advantages of design flexibility and low-cost casting procedures similar to gray iron. The difference between ductile iron and gray iron is in the graphite formation. Ordinary gray iron is characterized by a random flake graphite pattern in the metal. In ductile iron the addition of a few hundredths of 1 % of magnesium or cerium causes the graphite to form in small spheroids rather than flakes. These create fewer discontinuities in the structure of the metal and produce a stronger, more ductile iron. This nodular graphite structure inhibits the creation of linear cracks hence the ability to withstand distortion.
Ductile iron rolls – These are also known as nodular or spheroidal graphite cast iron rolls. These are heavy-duty industrial metal-working cylinders. Their metallurgy is defined by a unique structure where carbon precipitates as spherical graphite nodules rather than brittle flakes. This morphology is achieved through magnesium / cerium treatment.
Ductile machining – It is also ductile-regime machining. It is an advanced manufacturing process where hard, brittle materials, such as glass, silicon, or ceramics, are cut by forcing them to deform plastically like a metal, preventing micro-cracks and yielding a smooth, damage-free surface.
Ductile metals – These are the materials which can be easily shaped or deformed without breaking. These include carbon steels, aluminum, copper, and lead alloys, as well as alloy and stainless steels, zinc, magnesium, nickel alloys, and precious metals.
Ductile mode – It refers to the material removal mechanism in the machining of brittle materials, characterized by cutting below a critical depth of cut to achieve improved surface finish and minimize sub-surface cracking. This mode is influenced by factors such as tool geometry and cutting conditions. In structural mechanics, it describes a deformation process defined by plastic flow rather than sudden fracture.
Ductile mode cutting – It is a machining process where hard, brittle materials like glass, silicon, or ceramics are removed through plastic deformation rather than fracture. This occurs when the cutting depth stays below a critical nano-scale threshold, producing smooth, crack-free mirror surfaces.
Ductile rupture – It is a metal failure mode preceded by extensive permanent, plastic deformation. Rather than snapping suddenly, the metal stretches, bends, or ‘necks down’ (shrinks in cross-sectional area) before pulling apart. It absorbs high quantities of energy and provides visible warning signs before separating.
Ductile to brittle transition – At low temperatures some metals that would be ductile at room temperature become brittle. This is known as a ductile to brittle transition.
Ductile-to-brittle transition temperature – It is the temperature at which the material starts becoming brittle from ductile. Ductile to brittle transition takes place over a range of temperature.
Ductility – It is the ability of a material to deform plastically without fracturing, measured by elongation or of area in a tensile test, by height of cupping in an Erichsen test, or by other means. Galvanized steel is ductile within certain recommended bending radii.
Ductility index – It is a numerical ratio measuring a structure or material’s capacity to deform inelastically (plastically) before it breaks. It compares behaviour at the point of ultimate failure to behaviour at the initial point of yield.
Ductility screening – It reliably measures ductility without needing the larger, standard-sized dog-bone coupons used in uniaxial tensile tests.
Ductility test – It is a method used to assess the ability of a material, particularly electro-deposits, to deform under stress without cracking, typically performed through bend, torsion, tensile, or bulge tests. The results of these tests provide a semi-quantitative measure of the material’s ductility, influenced by factors such as the thickness of the coating and substrate.
Ductility testing – It evaluates a material’s capacity to undergo substantial plastic deformation (stretching or bending) without cracking or fracturing. It is important for determining if a metal can be safely formed into wires, sheets, or complex shapes through processes like rolling and drawing.
Duct liner -It is a specialized acoustic and thermal insulation material attached to the interior surface of sheet metal air distribution ducts. It is mainly engineered for broad-band sound attenuation to dampen fan noise and air turbulence, while offering secondary thermal resistance and condensation control.
Duct sheet – It is coiled or flat sheet in specific tempers, widths, and thicknesses, suitable for duct applications.
Duct sorbent injection – It is frequently called dry sorbent injection (DSI). It is an air pollution control technology. It involves blowing a fine, dry powder chemical, such as hydrated lime or sodium bi-carbonate, directly into an industrial exhaust pipe (flue gas duct) to capture and neutralize harmful acid gases before the gas leaves the smoke-stack.
Duct system – It consists of network of conduits, fittings, and plenums designed to transport air or cables. In HVAC (heating, ventilation, and air conditioning) engineering, it moves conditioned supply, return, and exhaust air to control indoor thermal comfort and air quality.
Duct tape – It is a high-strength, pressure-sensitive composite tape featuring a three-layer material design namely a polyethylene top backing, a central woven cloth mesh (scrim), and a heavy rubber-based adhesive bottom layer. This multi-layer structure provides high tensile strength, moisture resistance, and hand-tearability for temporary mechanical fixes.
Duct wall – It is the inner or outer boundary surface of a conduit used to guide fluids, air, or cables. This wall, such as its thickness, rigidity, thermal conductivity, and internal roughness, directly dictate pressure loss, heat transfer, and acoustic performance.
Due diligence – It is the degree of care and caution which is needed before making a decision.
Due diligence process – It is a systematic audit of a target organizational technology assets, software architecture, infrastructure, and engineering team capabilities to validate valuation and uncover hidden risks before a commercial transaction.
Dufour effect – It is a thermodynamic phenomenon where a mass concentration gradient (such as two different chemical species diffusing into each other) causes a spontaneous energy or heat flux. Even if a system starts at a uniform temperature, the movement of matter creates a localized temperature change. It is the reciprocal phenomenon to the Soret effect (also known as thermal diffusion).
Dugdale model – It is also called strip yield model. It is a fracture mechanics concept. It assumes that plastic yielding at a crack tip concentrates into a narrow, linear strip zone ahead of the crack. This zone acts as a cohesive continuation of the crack and experiences a constant yield stress, which removes unrealistic mathematical stress infinities.
Dulong-Petit law – It is a thermodynamic principle stating which the molar specific heat capacity of many solid elements is approximately constant, regardless of the element. It states that the molar heat capacity at constant volume (Cv) is roughly ‘3R’, where ‘R’ is the universal gas constant (around 25 joules per (mol.K).
Dumb-bell sample – It is also widely called a dog-bone sample. It is a standardized piece of material shaped with wide ends and a narrow centre (the gauge section). It is mainly used in tensile testing to measure a material’s mechanical properties, such as tensile strength, yield stress, and elongation.
Dummy – It is an imaginary activity inserted into the network to show a precedence relationship, but it does not represent any actual passage of time. It is an imaginary activity which needs no time and is used to maintain the appropriate precedence relationships in a programme evolution review technique (PERT) network.
Dummy activity – In activity-on-arrow diagrams, where arrows represent activities, dummy activities show logical relationships between activities. They are not actual activities themselves – dummy activity arrows are drawn with broken lines to differentiate them from regular activity arrows.
Dummy block – In extrusion, it is a thick unattached disk placed between the ram and the billet to prevent over-heating of the ram. It is a high-strength steel buffer attached to the press ram which transfers pressure to the billet while sealing the container.
Dummy cathode – It is a cathode, normally corrugated to give variable current densities, that is plated at low current densities to preferentially remove impurities from a plating solution. It is also a substitute cathode which is used during adjustment of operating conditions.
Dummy cell – It is an inactive or surrogate structural component added to a system, layout, or test set-up to mimic the physical, thermal, or electrical properties of real cells without performing active work. It ensures symmetry, uniformity, and accurate calibration.
Dummying – It is plating with dummy cathodes.
Dummy layer – It is a non-functional, sacrificial, or virtual structure added to a design, layout, or simulation model. Its main purpose is to balance physical, chemical, or computational constraints, such as ensuring uniform material density during manufacturing or stabilizing boundary conditions in computer models.
Dummy load – It is a simulated device which replaces a real electrical or radio frequency load. It absorbs output power and turns it into heat. This lets engineers test, tune, or run equipment safely without sending out live signals or damaging hardware.
Dummy point – It is an artificial marker with zero duration and no resources. It is used in network diagrams, like project evaluation and review technique / critical path method (PERT / CPM) to show logical dependencies or prevent naming errors between project events.
Dummy suffix – It is also called a dummy index. It is an index letter which appears twice in a single term of an equation. It indicates that a person is to sum the values over the entire range of that index.
Dummy variable – It is a variable in a regression model coded 1 if the case falls into a certain category of an explanatory variable and 0 otherwise. Used to represent qualitative predictors in a regression model.
Dump – It is a pile of broken rock or ore on surface.
Dump car – It refers to a specialized heavy-duty vehicle or rail-car equipped with an open box bed designed to transport and rapidly unload loose bulk materials, such as sand, gravel, ore, or construction waste, by tilting or opening its container through hydraulic, pneumatic, or gravity systems.
Dump combustor – It is a combustion device where a fuel-air mixture undergoes a sudden cross-sectional expansion as it enters a larger combustion chamber through a rear-ward-facing step. This sudden expansion creates stable flow separation and internal recirculation zones which naturally anchor and stabilize the flame.
Dumping – Dumping occurs when imported merchandise is sold in, or for export to the domestic market at less than the normal value of the merchandise, i.e., at a price that is less than the price at which identical or similar merchandise is sold in the comparison market, the home market (the market of the exporting country), or third-country market (in this case, ‘market’ is used as proxy for ‘home market’ in cases where home market cannot be used). The normal value of the merchandise cannot be below the cost of production.
Dump plane – It is the cross-sectional area where a fluid or fuel-air mixture undergoes a sudden cross-sectional expansion, typically transitioning from an inlet duct or nozzle into a larger combustion chamber or cavity.
Dumpy level – It is a commonly used leveling instrument to locate the points in same horizontal plane. It is also called as automatic level or builder’s level. Elevations of different points and distance between the points of same elevation can be determined by dumpy level.
Dune – It is a landform composed of wind-driven or water-driven sand. It typically takes the form of a mound, ridge, or hill. An area with dunes is called a dune system or a dune complex. A large dune complex is called a dune field, while broad, flat regions covered with wind-swept sand or dunes, with little or no vegetation, are called ergs or sand seas. Dunes occur in different shapes and sizes, but most kinds of dunes are longer on the stoss (up-flow) side, where the sand is pushed up the dune, and have a shorter slip face in the lee side. The valley or trough between dunes is called a dune slack. Dunes are most common in desert environments, where the lack of moisture hinders the growth of vegetation which otherwise interferes with the development of dunes.
Du Nouy ring method – It is a technique used to measure the surface tension of a liquid or the interfacial tension between two liquids. It involves pulling a submerged platinum-iridium ring through a liquid boundary and recording the maximum pull force needed before the liquid film breaks.
Duoplasmatron – It is a type of ion source in which a plasma created by an arc discharge is confined and compressed by a nonuniform magnetic field.
Duplex ageing – It is a two-age-hardening heat treatment conducted at different temperatures.
Duplex alloys – These are bearing alloys consisting of two phases, in which one is much softer than the other.
Duplex brass – It consists brasses with composition ranging from 58 % to 62 % copper with 38 % to 42 % zinc which have both alpha and beta phases present in their microstructure. Duplex brasses are superior to alpha brasses for hot working, but inferior for cold working.
Duplex coating system – It is the galvanized steel which has been coated with an additional corrosion inhibiting product, typically liquid, powder, or paint. The two separate coating systems work synergistically to provide enhanced corrosion protection. Duplex coating systems enhance the appearance or durability of the steel being protected.
Duplexer – It is a two-way electronic filter or switch in radio and radar engineering. It lets a single antenna handle both sending and receiving signals at the same time. It blocks high-power transmitted signals from reaching and breaking the sensitive receiver.
Duplex face dies – These are flat thread rolling tools which feature threaded / grooved rolling surfaces on both opposite sides of the die. Mainly used in reciprocating thread rolling machines, they allow for double the usage and longer life-spans compared to standard single-face dies.
Duplex fluid filter – It is an inline parallel filtration system with two identical chambers connected by a change-over valve. It allows one chamber to filter fluid while the other stays on standby. Operators switch the flow during cleaning to ensure zero system downtime.
Duplex grain size – It is the simultaneous presence of two grain sizes in substantial quantities, with one grain size appreciably larger than the others. It is also termed mixed grain size.
Duplexing – It consists of any two-furnace melting or refining process. It is also called duplex melting or duplex processing.
Duplex micro-structure – It is a two-phase structure. It refers to a material’s internal structure consisting of two distinct phase components co-existing in roughly equal proportions. This configuration allows the material to blend the physical and chemical properties of both phases into a single, high-performance alloy. The term is most famously used in reference to duplex stainless steels.
Duplex operation – It refers to a sequential, two-stage manufacturing or melting method where metal is processed in two different furnaces or converters consecutively to save time, optimize chemical refining, and cut costs. Duplex operation is also a point-to-point communication system which allows data transmission in two directions. It is split into half-duplex (alternating directions) and full-duplex (simultaneous directions) modes, using specific methods like frequency separation or time-sharing.
Duplex probe – It refers to a sensor or analytical tool built with two independent sensing elements or pathways enclosed within a single physical housing, sheath, or molecular structure. This dual design provides built-in redundancy, simultaneous multi-parameter tracking, or improved target-binding efficiency.
Duplex process – In duplex process route of stainless-steel production, melting is carried out in electric arc furnace / induction furnace which is followed by refining in a converter. The duplex process tends to be flexible with respect to raw material selection.
Duplex pump – It is a positive-displacement reciprocating pump featuring two side-by-side cylinders (pistons or plungers). Duplex pump’s strokes alternate so that as one piston discharges fluid, the other draws the fluid in. This movement provides a smoother, more continuous fluid flow than a single-cylinder (simplex) pump.
Duplex stainless steels – These steels have a mixed structure of bcc ferrite and fcc austenite. The amount of each phase is a function of composition and heat treatment. Most stainless steels are designed to contain about equal amounts of each phase in the annealed condition. The principal alloying elements are chromium and nickel, but nitrogen, molybdenum, copper, silicon, and tungsten can be added to control structural balance and to impart certain corrosion-resistance characteristics. The corrosion resistance of duplex stainless steels is like that of austenitic stainless steels with similar alloying contents. However, duplex stainless steels possess higher tensile and yield strengths and improved resistance to stress-corrosion cracking than their austenitic counterparts. The toughness of duplex stainless steels is between that of austenitic and ferritic stainless steels.
Duplex strainer – It is an industrial dual-chamber filtration device with a flow-diverting valve. It removes solid debris from fluids without system downtime. When one basket fills, flow switches to the second basket so the first can be cleaned safely.
Duplex surface treatments – These treatments refer to the sequential combination of two distinct surface engineering processes (like diffusion and coating) applied to a metal to create a highly optimized, multi-layered surface profile. This technique overcomes the limitations of using a single treatment. A duplex treatment is engineered to maximize performance, with typical methods producing a hard, wear-resistant top layer and a deep, strengthened bottom layer. It normally involves two sequential, frequently uninterrupted metallurgical steps.
Duplex treatment – It is the combination of two sequential surface modification or heat treatment processes. It typically joins a thermo-chemical diffusion process (like plasma nitriding) with a hard surface coating, like physical vapour deposition (PVD), to maximize wear resistance, load support, and bond strength.
Duplicate measurement – It is a second measurement made on the same (or identical) sample of material for assisting in the evaluation of measurement variance.
Dupre equation – It defines the thermodynamic work of adhesion (Wa) needed to separate a unit area of two contacting phases (like a liquid and a solid) into two separate independent surfaces. Expressed as ‘Wa = gamma-L + gamma-S – gamma-SL’, where ‘Wa’ is the work of adhesion per unit area, ‘gamma-L’ is the surface tension (or energy) of the liquid phase, ‘gamma-S’ is the surface free energy of the solid phase, and ‘gamma-SL’ is the interfacial tension between the solid and liquid. Dupre equation links surface tensions to adhesive bond strength.
Durability – It is the ability of a metal or alloy to maintain its structural integrity and functionality over its intended service life without significant degradation. It is not a single property, but a combination of mechanical, chemical, and physical traits that allow the metal to resist. It also refers to the ability of a material or product to withstand wear, pressure, or damage over an extended period. It is a critical factor in determining the life-span and reliability of products across different industries.
Durability analysis – It evaluates a component or structure’s ability to resist functional failure, cracking, or material degradation under repeated, cyclic, or long-term operational loads over its target life-span.
Durability assessment – It is the systematic process of evaluating a material, component, or system’s ability to withstand mechanical, thermal, and environmental loads over its target service life without structural failure or unacceptable degradation.
Durability class – It is a standardized rating system which categorizes a material or structure’s ability to resist long-term degradation, weathering, or operational wear over its intended service life without major failure or extensive maintenance.
Durability concrete – It is the concrete with improved resistance to degradation, particularly in challenging environments such as those exposed to chloride attack, but it does not necessarily possess high strength. It is characterized by the use of pozzolanic binders to reduce capillary pore size and improve chemical resistance.
Durability design – It is a systematic approach to ensuring a structure, material, or product maintains its needed performance and functionality over a specified service life without unexpected failure or excessive maintenance. It evaluates environmental loads, wear mechanisms, and material degradation limits during the initial planning phase.
Durability of an adhesive bond – It is the ability of a joined interface to maintain its structural integrity and mechanical strength over time when exposed to continuous loads and specific service environments.
Durability performance – It is the capacity of a material, component, or system to resist deterioration and maintain its needed functional performance over a specified design life without needing major repairs.
Durability specification – It is a documented set of requirements, constraints, and test parameters designed to ensure a material, component, or structure resists deterioration and remains functional over its target service life without major maintenance.
Durable construction material – It is a substance which resists weathering, chemical attack, abrasion, and other forms of deterioration, maintaining its structural integrity and required service life with minimal maintenance.
Durable material – It is one which resists wear, corrosion, and chemical breakdown. It keeps its shape and works well for a long time without needing much fix-up work.
Durable repair – It is an intervention which restores a structure or component to its needed service potential and enables it to withstand operational and environmental degradation for a specified extended life-span without premature failure or excessive maintenance.
Durability till complete failure – It refers to a metal’s capacity to withstand operational loads, stresses, and environmental degradation over time before it entirely loses functionality or fractures. It is typically quantified by the total service hours, operational cycles, or stress cycles a component endures.
Duralumin – It is an obsolete term. This term is frequently applied to the class of age-hardenable aluminum-copper alloys containing manganese, magnesium, or silicon.
Duration time – It is the total active or calendar time span needed to complete a specific task, process, or project from its start point to its end point. It is measured in units like seconds, hours, or work days.
Durham matrix-based methodology – It is a hierarchical, visual systems-design approach. It is used to structure highly complex, multi-variable design processes, such as shape / section rolling, by mapping overlapping metallurgical parameters into interactive decision matrices.
Durometer – It is the Durometer (also called shore Durometer) measures hardness in terms of material elasticity. A diamond-tipped hammer is used to strike the testing surface from a known height. The rebound of the hammer is measured. The harder is the material, the higher is the rebound.
Durometer hardness – It is a measure of the indentation hardness of plastics. It is the extent to which a spring-loaded steel indenter protrudes beyond the pressure foot into the material.
Durometer hardness test – It involves forcing a 30-degree tapered indenter into the surface of the sample using calibrated loading springs. A dial gauge indicates the depth of penetration in durometer numbers, which are directly proportional to the load on the spring.
Durometer reading – It is an index which is used for ranking the relative hardness of elastomers.
Dust – It is the fine, dry powder consisting of tiny particles of earth or waste matter lying on the ground or on surfaces or carried in the air. Exhaust gases normally have dust particles entrained in them.
Dust abatement – It is the process of reducing, suppressing, or capturing solid particulate matter before it becomes airborne or spreads into the environment. It protects worker health, stops visibility loss, and prevents environmental pollution at construction sites, mines, and industrial plants.
Dust catcher – It is an equipment for the removal of coarse particles from the exhaust gas of a furnace. The internal construction of the dust catcher is such that there is a sudden change in the direction of the flow of exhaust gas. This causes the large dust-particles to separate because of its higher momentum. The separated particles then settle down because of gravitational force. In blast furnace ironmaking, it is situated by the side of cast house and used for preliminary cleaning of blast furnace gas. It works on the principle of reversing the direction of flow of blast furnace gas for separating coarse dust particles from blast furnace gas.
Dust cloud – It is a suspension of fine solid particles mixed in a gas (like air). It forms through mechanical processes like grinding, crushing, or material handling. When the particles are combustible, the cloud creates severe explosion and fire risks in industrial plants.
Dust collection system – It consists of equipment capturing and removing dust generated during conveyor operations, demanding regular maintenance to uphold air quality and prevent system clogging.
Dust collector – It is a system used to improve the quality of air released from industrial processes by collecting dust and other impurities from air or gas. It is designed to handle high-volume dust loads. A dust collector system consists of a blower, dust filter, a filter-cleaning system, and a dust receptacle or dust removal system.
Dust explosion – It is the rapid combustion of fine, flammable particles suspended in the air within a confined or semi-confined space. This combustion generates a fast-moving flame front, extreme heat, and a destructive pressure wave.
Dust generation – It is the physical process where mechanical, thermal, or chemical forces break down solid materials or agitate dry powders. This action releases fine, solid particles (typically under 100 micro-meters in diameter) into the surrounding air or work-space.
Dust holding capacity – It is the total mass of particles a filter medium can accumulate before its flow resistance reaches a specified final pressure drop limit. It measures how much dirt a filter holds before it requires replacement or cleaning.
Dusting – It is a phenomenon, normally affecting carbon-base electrical motor brushes or other current carrying contacts, wherein at low relative humidity or high applied current density, a powdery ‘dust’ is produced during operation. It is also applying a powder, such as sulphur to molten magnesium or graphite to a mould surface.
Dusting system – It is a mechanical system used to apply inert rock dust in under-ground coal mines to increase the incombustible content of admixtures, hence quenching flame propagation and mitigating coal dust explosions. These systems can operate through different methods, including high-pressure machines which disperse dust effectively in areas inaccessible to personnel.
Dust layer – It is an accumulation of settled solid particles on a surface or stratified within a medium. It poses critical safety, thermal, and mechanical challenges in industrial, mining, and environmental systems.
Dusty material – It is a finely divided solid substance with a high propensity to release airborne particulate matter (aerosols) when subjected to mechanical, pneumatic, or aerodynamic handling. These materials easily generate fugitive dust emissions during transport, crushing, mixing, or pouring.
Dutchman – It is a short section of the belt with lacing in a conveyor belt, removable when take-up provision has been exceeded, necessitating periodic checks.
Duty – It is the specification which gives the load, ambient temperature, and speed under which surfaces are required to move.
Duty class – It is a standardized rating system which categorizes equipment, such as electric motors or cranes and hoists, based on their operating time, load intensity, frequency of use, and cooling cycles. It ensures machinery is robust enough to handle thermal stress and mechanical wear without failing prematurely.
Duty classification – It categorizes equipment based on operational intensity, load variations, running duration, and rest periods. It ensures machinery, like electric motors or cranes, is safely matched to its working environment without overheating or premature structural failure.
Duty cycle – The duty cycle refers to the ratio of a crane’s working time to its total cycle time. In simpler terms, it indicates how frequently a crane is expected to perform its lifting operation in each time frame. It is the proportion of time during which a crane is operated. The duty cycle is expressed as a ratio or as a percentage.
Duty, machine – Machine duty refers to the specific load cycle, operating conditions, and time duration a device or motor experiences. It defines whether a machine runs continuously, starts and stops frequently, or handles heavy loads.
Duty parameter – It is the product of the Sommerfeld number and the square of the length-to-diameter ratio of a journal bearing.
Duty ratio – It is the fraction of one complete signal period which a system, device, or wave-form spends in an active or ‘on’ state. It is expressed as a decimal value between 0 and 1, or as a percentage.
Duty vehicle classification – It defines a vehicle based on its weight limits, structural strength, and operational capacity, which directly dictates its design requirements, load limits, and regulatory testing standards.
Dwell – It is the portion of a press cycle during which the movement of a member is zero or at least insignificant. It normally refers to (i) the interval when the blank-holder in a drawing operation is holding the blank while the punch is making the draw, or (ii) the interval between the completion of the forging stroke and the retraction of the ram.
Dwell period – It is the specific duration during which a system, component, or machine pauses, remains stationary, or stays in a particular state while input motion or processing continues.
Dwell time – It is the specific duration a material is held at a constant temperature during a heat treatment process (like annealing, quenching, or tempering) to ensure it reaches a uniform temperature throughout and achieves the desired microstructural changes.
Dyadic scale – It refers to a binary scaling progression where parameters, intervals, or resolutions change by powers of two (‘2 to the power j’, where ‘j’ is an integer). It is widely used to discretize continuous spaces, signals, or physical systems into hierarchical octaves or levels.
Dyadic tensor – It is a mathematical representation of a second-order tensor, created by the outer product of two vectors. It is used to model directional physical properties such as stress, strain, elasticity, and thermal conductivity that require nine components to define. Mathematically, a dyadic tensor represents the linear transformation of one vector into another. It is defined as the dyadic or tensor product of two vectors.
Dyadic wavelet transform – It is a signal processing method which breaks down a signal or image using scale and position values based on powers of two (‘2 to the power j’, where ‘j’ is an integer) It applies digital filters to split data into coarse approximation parts and fine detail parts across multiple octave bands.
Dye – It is a natural or synthetic substance used to impart colour to materials. It differs from a pigment because it dissolves in a liquid (aqueous solution), allowing the colour to chemically bind to the material and resist washing or fading.
Dyeability – It is a measure of how well a fibre, or polymer surface absorbs and retains a dye. It depends on factors like surface wetness, chemical bonding sites, and internal pore structure.
Dyeing machine – It is an industrial mechanical system designed to apply uniform colour to fibres. It controls thermal energy, fluid dynamics, and chemical concentration to ensure dye molecules adsorb and diffuse evenly into the molecular structure of the material.
Dyeing process – It is the mass-transfer and chemical-bonding operation where colourants (dyes or pigments) migrate from an aqueous solution onto a fibre surface, diffuse into the internal polymer matrix, and permanently fix through chemical or physical interactions
Dye liquor – It is the liquid solution inside a dye bath which contains water, dissolved or dispersed dye molecules, and specific chemical auxiliaries (such as salts, acids, alkalis, and leveling agents) used to colour materials.
Dye molecule – It is an organic compound which absorbs specific wave-lengths of visible light and chemically or physically binds to substrates like fibres, plastics, or semi-conductors to impart lasting colour. These structures are rationally designed by modifying light-absorbing chromophores, electron-donating auxochromes, and specific functional anchor groups to optimize optical properties, stability, and binding affinity.
Dye penetrant – It is the penetrant which is used to crack detection, which has a dye added to make it more readily visible under normal or black-lighting conditions. In the case of normal lighting, the dye is normally red and non-fluorescent. With black lighting, the dye is fluorescent and yellow-green in colour.
Dye penetrant inspection – It is also known as liquid penetrant testing. It is a low-cost, non-destructive testing (NDT) method used to detect surface-breaking defects, such as cracks, porosity, or leaks, in non-porous materials like metals, plastics, and ceramics. The inspection relies on capillary action, where fluid is naturally drawn into fine, microscopic surface flaws.
Dye-penetrant test – This is used to detect cracks and involves spraying a dye on the area to be tested. After allowing time for penetration, the surplus dye is removed and the area is then sprayed with a white developer. Any faults are revealed as coloured lines or spots caused by the developer absorbing the dye seeping from the cracks. If more sensitive results are needed, a fluorescent dye is used and the same process is followed. When viewed under ultra-violet light any defects show as a highly fluorescent line or spot.
Dye-penetrant testing – It is a cost-effective, non-destructive testing method used to reveal surface-breaking flaws in non-porous materials like metals, plastics, or ceramics. It utilizes capillary action to draw a pigmented or fluorescent liquid into tiny cracks, pores, and defects.
Dye-scan fluorescent tracer liquids – These are specialized UV (ultra-violet)-reactive compounds mainly used for quality control during shot peening. In this process, the tracer is applied to a metal surface and allowed to dry into an elastic film. When bombarded by media (shot peening), the film breaks away in the peened areas, revealing the degree of coverage under UV (ultra-violet) light.
Dye sensitization – It is a surface modification technique which coats wide-band-gap semi-conductors with light-absorbing dye molecules to capture lower-energy photons and trigger targeted electron transfer reactions.
Dye-sensitized solar cells – These are low-cost, thin-film photo-voltaic devices which mimic plant photosynthesis to convert light into electricity. They use light-absorbing dye molecules layered over a nano-structured semi-conductor (normally titanium di-oxide, TiO2) and a redox electrolyte to generate current, replacing the traditional p-n junction found in silicon cells. These solar cells are wet solar cells consisting of two conductive glasses separated by an electrolyte solution, where one glass has a porous titania (TiO2) film coated with a dye, functioning as the light-absorbing layer. They are noted for their ease of production and relatively high conversion efficiency, around 11 %.
Dye tracing – It is a method of tracking and tracing different flows using dye as a flow tracer when added to a liquid. Dye tracing can be used to analyze the flow of the liquid or the transport of objects within the liquid. Dye tracking can be either qualitative, showing the presence of a particular flow, or quantitative, when the quantity of the traced dye is measured by special instruments.
Dyke – It is a long and relatively thin body of igneous rock which, while in the molten state, intruded a fissure in older rocks.
Dynamic – It means moving, or having high velocity. It is frequently used with high strain rate (less than 0.1 second) testing of metal samples.
Dynamic access control – It enables administrators to apply access-control permissions and restrictions based on well-defined rules which can include the sensitivity of the resources, the job or role of the user, and the configuration of the device which is used to access these resources.
Dynamic adaptation – It is a system’s ability to automatically alter its structure, behaviour, or parameters in real-time during execution to respond to shifting environmental conditions, user needs, or external disturbances without restarting.
Dynamical behaviour – It refers to how a system changes, moves, or responds over time when acted upon by varying forces, inputs, or environmental conditions. It contrasts with static behaviour, focusing instead on transient states, vibrations, growth, oscillations, and stability.
Dynamical equation – It is a mathematical expression, typically an ordinary or partial differential equation, which defines how a system’s state variables change over time in response to internal parameters and external forces.
Dynamically recrystallized grain size – It refers to the average diameter of new, strain-free grains which nucleate and grow in a material during plastic deformation. It is determined by a dynamic balance between the accumulation of dislocations (strain energy) and the continuous nucleation of new grain structures.
Dynamical systems approach – It models how a physical system’s state changes over time using differential or difference equations. It relies on state variables, a state space, and an evolution rule to analyze system stability, control response, and behaviour.
Dynamical systems theory – It is a mathematical framework used to analyze how physical or abstract systems change over time. It relies on differential or difference equations to model system states, predict future behavior, and design control strategies for stability and performance.
Dynamical theory – It is a theoretical framework used to model the scattering of X-rays in crystals, originally proposed in geometrical form and later developed to account for imperfections in materials. This theory provides the basic equations in differential form to analyze variations in crystal perfection and has been further refined to accommodate multi-layer structures.
Dynamic amplification factor – It is the ratio of a structure’s peak dynamic response (such as displacement, stress, or force) to its static response under the same load magnitude. It measures how much worse or larger an effect becomes when a load is applied quickly or cyclically instead of slowly.
Dynamic analysis – It involves examining the behaviour of software or systems by observing their execution during runtime. It is a method of testing and evaluating software while it is actively running, allowing for the detection of errors, vulnerabilities, and performance issues which might not be apparent through static analysis alone.
Dynamic array – It is a data structure which automatically grows or shrinks in size. It fixes the rigid size limit of a static array by managing a larger underlying block of memory, doubling its capacity when full, and providing fast access to elements.
Dynamic balance – It is the state where a rotating body produces no net centrifugal forces or twisting moments (couples) while in motion. This is achieved when the rotor’s mass is distributed evenly across multiple planes, aligning its mass centre with the geometric axis of rotation to stop vibrations.
Dynamic band-width – It refers to a mechanism that allows applications to adjust their allocated band-width in real-time to adapt to work-load changes or meet ‘quality of service (QoS)’ needs. This mechanism enables nodes to request more bandwidth by simulating new nodes in the system, thence increasing the available slots for data transmission. Dynamic band-width is a real-time network management technique which assigns transmission capacity based on live traffic demand rather than fixed static limits. It optimizes shared network resources like passive optical networks.
Dynamic band-width allocation – It is a technique which assigns network transmission capacity in real-time based on live traffic demands rather than fixed, static limits. It maximizes efficiency by shifting unused resources from inactive nodes to active ones, commonly used in passive optical networks (PONs).
Dynamic behaviour – It is the process of specifying how a system, structure, or material responds to time-varying loads, forces, or environmental changes rather than constant or static conditions. It involves defining parameters like inertia, damping, and stiffness to predict real-world performance.
Dynamic boundary conditions – These are time-dependent rules where variables at a system’s edge follow their own evolutionary laws and interact directly with the interior domain. Unlike static constraints, they account for changing forces, mass, or energy flux across an active interface.
Dynamic braking system – It is a braking system which slows down or stops the conveyor belt, needing regular maintenance for proper functionality and safety.
Dynamic buckling – It is a sudden loss of structural stability under time-dependent, rapidly applied, or impact loads (such as pulses or vibrations). Unlike static buckling, where loads increase slowly, dynamic loading amplifies small imperfections and inertia forces, causing structural collapse or wild lateral vibrations at lower or shifting thresholds.
Dynamic buckling load – It is the critical threshold of a time-dependent, transient, or oscillatory force (such as a pulse, impact, or harmonic load) which causes a sudden, catastrophic loss of structural stability. Unlike static buckling, this threshold depends on load duration, rate of application, structural inertia, and initial geometric imperfections.
Dynamic characteristics – These characteristics of the instrument are concerned with the measurement of quantities which vary with time. These characteristics are those which change within a period of time which is normally very short in nature. The different dynamic characteristics are speed of response, fidelity, lag, and dynamic creep.
Dynamic charge acceptance – It is a battery metric defining a cell’s ability to absorb high-rate, short-duration charge pulses, such as from regenerative braking, while operating in a partial state-of-charge micro-cycling window. It is quantified as the average charging current normalized to the battery’s nominal capacity (ampere, A / ampere hour, Ah).
Dynamic coefficient – It very frequently refers to the coefficient of dynamic (kinetic) friction, which is the ratio of the frictional force resisting motion to the normal force when two surfaces slide against each other. It can also describe parameters in system dynamics, bearings, or fluid flow.
Dynamic compaction – It is a geo-technical ground improvement technique. It densifies loose soils and uncompacted fills by repeatedly dropping a heavy steel or concrete weight (typically 8 tons to 36 tons) from a crane at heights ranging from 10 meters to 40 meters in a systematic grid pattern.
Dynamic component – It is the practice of designing modular software or physical building blocks which adapt, render, or change behaviour at run-time based on set rules, data contexts, or user actions. It replaces static structures with flexible logic.
Dynamic compression – It is the conversion of the air velocity into pressure. Dynamic machines use axial and centrifugal impellers to impart velocity to the air, which is then converted to pressure. Centrifugal and axial compressors are dynamic machines often operating at high speeds.
Dynamic compressor – It is a continuous-flow machine which increases gas pressure by imparting high velocity (kinetic energy) to the gas using rotating blades or impellers, and then converting that velocity into pressure energy inside a stationary diffuser. Dynamic compressors include centrifugal and axial compressors and are utilized in different industries for feeding, transporting, or compressing gases.
Dynamic consolidation – It is a geo-technical ground improvement technique where a heavy weight (10 tons to 30 tons) is repeatedly dropped from a crane at high heights (10 meters to 40 meters) onto a soil surface. It densifies loose soils, uncompacted fills, and saturated cohesive soils by generating high-pore water pressures which break down soil structure and expel water.
Dynamic contact angle – It is the contact angle formed when a liquid-gas or liquid-liquid interface moves across a solid surface. Unlike static contact angles measured at rest, dynamic angles quantify active wetting or de-wetting processes and depend heavily on the velocity and direction of the moving three-phase contact line.
Dynamic contrast – It is an automated image adjustment method which actively varies back-light or projector output to boost a display’s contrast ratio.
Dynamic crack propagation – It is the rapid, unstable growth of a fracture tip through a material under high-speed or impact loading. Unlike static fracture, it needs accounting for material inertia, kinetic energy, and stress wave reflections since the crack tip can travel at hundreds of meters per second.
Dynamic crystalline materials – These materials are defined by their ability to change parameters such as structure, mass, momentum, and energy fluxes in response to environmental changes. This makes them thermodynamically open systems, constantly exchanging these quantities with their surroundings.
Dynamic deformation – It occurs when a structure is subject to the actions of flutter, impact, and so on. Dynamic deformation is caused by rapid, high-strain-rate forces (frequently exceeding 100 strain per second) from sudden impacts, explosions, or vibrations. It differs from static deformation since rapid loading alters internal mechanics, increasing material strength and creating localized failure patterns.
Dynamic electrode force – It is the electrode potential measured when current is passing between the electrode and the electrolyte.
Dynamic equilibrium – It describes a system in motion where opposing forces, moments, or transfer rates balance out completely. Macroscopic properties remain steady and unchanged over time, while active internal processes or movements continue at equal rates.
Dynamic equilibrium equation – It refers to a set of second-order partial differential equation which describes the balance of forces and moments in two-dimensional solids under dynamic conditions, incorporating inertia terms and external forces. It sets the sum of external forces, damping forces, elastic forces, and inertia forces equal to zero (using D’Alembert’s principle) or equates them to an applied time-varying load.
Dynamic factor – It is the ratio of maximum dynamic response (or load) to the static response (or load) under the same conditions. It measures how much an oscillating or sudden load increases structural stress compared to a steady, stationary load.
Dynamic fatigue – It is the progressive structural damage a material undergoes when subjected to repeated, time-varying (dynamic) loads. Over time, these cyclic stresses cause microscopic cracks to form and grow, eventually leading to sudden structural failure at stress levels far below the material’s static ultimate strength.
Dynamic fatigue test – It is a laboratory method which subjects a material or component to repeated, oscillating cyclic loads. It measures durability and life-span by identifying how many stress fluctuations a part can handle before cracking or breaking, even when forces stay well below the static yield strength.
Dynamic fault tree – It is a fault tree which incorporates additional gates to model dynamic behaviour within a system, allowing for a more comprehensive analysis of failure propagation.
Dynamic feed-back control – It is a closed-loop system mechanism which continuously measures a system’s output, compares it to a target set-point, and uses the resulting error to adjust the input dynamically, ensuring stability and performance despite external disturbances.
Dynamic field – It is the practice of designing adaptable data schemas, user interfaces, or object models where attributes and properties can be added, modified, or loaded at runtime rather than being hard-coded permanently. This approach is used in software development, data-base design, and CAD (computer aided design) systems to handle variable user inputs and large-scale data structures.
Dynamic filtration – It is also called shear-enhanced filtration. It is a separation process which prevents the build-up of solids on a filter medium by utilizing active mechanical movement. Unlike static filtration, it uses rotation, vibration, or oscillation to create high shear forces and turbulence. This keeps particles in suspension, prevents clogging, and boosts filtration efficiency.
Dynamic fracture – It is the crack growth process occurring under rapidly changing loads and crack geometry, where inertial forces are to be considered, distinguishing it from static fracture mechanics. It encompasses problems related to crack initiation, propagation, and arrest in response to dynamic loading conditions.
Dynamic fracture mechanics – It is a field which studies how cracks grow in materials under fast-loading conditions where material inertia and stress waves matter. It tracks crack starting points, rapid movement, branching, and stopping.
Dynamic fracture toughness – It is a material’s resistance to crack start and fast growth under rapid, high-speed or impact loading. It uses stress and energy rules which change when a crack moves fast, accounting for rapid load changes and material inertia forces.
Dynamic frequency scaling – It is a computer architecture power-management technique which adjusts a micro-processor’s clock frequency on the fly. It scales the frequency up during heavy tasks and down during idle or low-demand periods to reduce power usage and thermal output. It is frequently paired with voltage scaling (dynamic voltage and frequency scaling, DVFS) for maximum efficiency.
Dynamic frequency selection – It is a regulatory mechanism which allows wireless devices, such as Wi-Fi access points, to dynamically detect radar signatures in the 5 GHz (giga-hertz) spectrum and switch channels to prevent harmful co-channel interference.
Dynamic friction – it is the friction under conditions of macroscopic relative motion between two bodies. This term is sometimes used as a synonym for kinetic coefficient of friction. However, it can also be used merely to indicate that the type of friction being indicated is associated with macroscopic motion rather than static conditions.
Dynamic gain tilt – It is the shift in the amplification spectrum of an optical amplifier, such as an Erbium-doped fibre amplifier (EDFA), caused by changes in total input signal power. As channels are added or dropped in WDM (wave-length division multiplexing) networks, gain saturation alters the amplifier slope, skewing power levels unevenly across wave-lengths.
Dynamic grain growth – It is the process where the crystallites (grains) of a metal increase in size during plastic deformation at high temperatures (typically above half the metal’s melting point). It is a microstructural restoration mechanism driven by the reduction of internal energy stored in grain and sub-grain boundaries.
Dynamic impact bed – It is a specialized component for absorbing and mitigating the impact of material loading onto the conveyor belt, necessitating periodic inspections for wear and effective functionality.
Dynamic input – It refers to a drawing aid feature that allows users to specify distances and angles directly on the screen while creating shapes in design software, improving efficiency by enabling on-the-fly adjustments to parameters like length and angle during the drawing process. It also refers to the design and mathematical structuring of time-varying control or data inputs for complex systems (such as robotics, multi-agent networks, or non-linear plants) where input vectors are re-defined or transformed on-the-fly to linearize dynamics, simplify control laws, or adapt to changing operational constraints.
Dynamic instability – It is a condition where a system subjected to a time-varying or operating load responds to a minor disturbance with escalating, uninhibited oscillations or divergent deformation over time. Unlike static instability (which deals with load limits like simple buckling), dynamic instability involves inertial, damping, and stiffness forces causing structural or fluid failure.
Dynamic insulation material – It is an advanced thermal technology where the material’s thermal conductivity or effective heat transfer changes adaptively. Unlike fixed insulation, dynamic insulation material (DIM) systems use porous permeable structures which allow controlled air or fluid flow, or active lattice adjustments, to recover escaping heat and regulate building envelope temperatures.
Dynamic load – It is an imposed force which is in motion, i.e., one that can vary in magnitude, sense, and direction.
Dynamic loading – It refers to the rapid application of time-varying forces, such as impacts, vibrations, or cyclic stresses. Unlike static loads (which are steady), dynamic forces induce high strain rates and inertial effects, accelerating metal fatigue and increasing the risk of brittle fracture.
Dynamic loading conditions – These conditions refer to forces applied to a metal which rapidly change in magnitude, direction, or position over time. Unlike static loads, which are constant and steady, dynamic loads induce traveling stress waves and high strain rates within the metal’s crystalline structure.
Dynamic loads because of unbalanced masses – Unbalanced forces in rotating machines are created when the mass centroid of the rotating part does not coincide with the axis of rotation. In theory, it is possible to precisely balance the rotating elements of rotating equipments. In practice, this is never achieved and slight mass eccentricities always remain. During operation, the eccentric rotating mass produces centrifugal forces which are proportional to the square of equipment speed. Centrifugal forces normally increase during the service life of the equipment because of the conditions such as equipment wear, rotor play, and dirt accumulation. A rotating equipment transmits dynamic force to the foundation predominantly through its bearings (with small, normally unimportant exceptions such as seals and the air gap in a motor). The forces acting at the bearings are a function of the level and axial distribution of unbalance, the geometry of the rotor and its bearings, the speed of rotation, and the detailed dynamic characteristics of the rotor-bearing system. At or near a critical speed, the force from rotating unbalance can be substantially amplified, sometimes by a factor of five or more.
Dynamic load test – It is a diagnostic method which applies a rapid, high-intensity impact force, normally through a falling hammer, to a structural element like a pile foundation. Sensors measure force and motion data to evaluate load capacity, material integrity, and stress distribution.
Dynamic load testing – It is a method to assess a pile’s bearing capacity by applying a dynamic load to the pile head (a falling mass) while recording acceleration and strain on the pile head. Dynamic load testing is a high strain dynamic test which can be applied after pile installation for concrete piles. For steel or timber piles, dynamic load testing can be done during installation or after installation.
Dynamic loss – It refers to the energy losses which occur during the transition between the on-state and off-state of a switch in power electronics, including turn-on and turn-off losses, and are proportional to the switching frequency. It also refers to the dissipation or reduction of energy in a physical system caused by active changes, movement, turbulence, or transitions, rather than steady-state friction.
Dynamic magnification factor – It is the ratio of a system’s maximum dynamic displacement (or response) under a periodic force to the static displacement caused by that same force applied slowly. It measures how much an oscillating load amplifies structural movement.
Dynamic magnifier – It is the ratio of the steady-state amplitude of a forced vibration to the deflection caused by a static load. It shows how much a dynamic or alternating force magnifies structural movement compared to a steady push.
Dynamic material modelling – It is a theoretical framework which optimizes hot-working processes (like forging or rolling) by treating the metal work-piece as an energy dissipator. It predicts how a material’s micro-structure evolves during deformation in order to maximize product quality and prevent structural defects.
Dynamic materials model – It is a metallurgical framework used to optimize hot working processes (like forging, rolling, and extrusion) by predicting material behaviour, preventing microstructural defects, and determining the safest processing conditions.
Dynamic mechanical analysis – It is a thermal-mechanical technique which measures the visco-elastic properties of materials, especially polymers and elastomers, by applying an oscillating force to a sample while varying temperature or frequency. It quantifies how a material’s stiffness, elasticity, and energy dissipation change over time. During a dynamic mechanical analysis test, the instrument measures both the applied stress and the resulting strain. This allows it to calculate three main characteristics namely storage modulus, loss modulus and tan delta.
Dynamic mechanical analyzer – It is an instrument used to evaluate the visco-elastic properties of materials by applying a small, oscillating sinusoidal force (stress) and measuring the resulting deformation (strain). It tests how materials respond under varying temperatures, frequencies, and time.
Dynamic mechanical measurement – It is a technique in which either the modulus and / or damping of a substance under oscillatory load or displacement is measured as a function of temperature, frequency, or time, or a combination thereof.
Dynamic mechanics – It is the branch of engineering mechanics which studies bodies in motion or objects undergoing acceleration due to external forces. It contrasts with statics, which deals with bodies at rest or in equilibrium.
Dynamic melting – It is an advanced heat transfer improvement technique used in thermal energy storage systems (such as latent heat storage units). It involves actively recirculating the already-liquid phase change material (PCM) using a pump or forced flow loops as it melts. This shifts the heat transfer mechanism from slow natural convection to rapid forced convection, considerably speeding up the overall melting process.
Dynamic metallurgical mechanism – It refers to microstructural or chemical changes that occur in a metal while it is actively being subjected to heat, stress, or deformation. These processes dictate how an alloy behaves during manufacturing and determine its final strength, flexibility, and overall structural integrity. These mechanisms are mainly studied to understand how processing history alters the internal architecture of a metal.
Dynamic method – It is the practice of writing code which builds or adds new functions while a programme runs. Instead of writing every function ahead of time, the system creates tools or behaviours on the fly based on user input or live data.
Dynamic microstructural mechanisms – These are physical and structural changes which happen to a metal’s crystal lattice while it is being hot-worked (e.g., rolling, forging, or extrusion).
Dynamic model – It is the process of creating mathematical or logical representations of physical systems which change over time. It tracks how variables like mass, energy, or data flow react to external inputs and forces. Engineers use this approach to predict system behaviour, test control strategies, and optimize performance before building physical prototypes.
Dynamic modulus – It is the ratio of stress to strain under cyclic conditions (calculated from data got from either free or forced vibration tests, in shear, compression, or tension).
Dynamic modulus of elasticity – It describes a material’s resistance to deformation under dynamic or time-varying loads, typically measured as the slope of the stress-strain curve under dynamic conditions. It is frequently higher than the static modulus, measured under slow, steady loading, and is used in areas like geo-technical engineering to assess structural stability under dynamic forces like vibrations or earthquakes.
Dynamic nature – Dynamic nature of a system describes its tendency to change, adapt, or respond to forces, loads, and environmental factors which vary over time rather than remaining constant.
Dynamic optical network – It is a high-speed communication infrastructure which uses software and smart hardware to set up, change, and turn off light-based data paths in real time. Unlike old systems that need manual fixes, it changes fast to match network traffic.
Dynamic performance – It measures how quickly and accurately a system reacts to changing inputs, loads, or disruptions over time. It evaluates transient behaviour, stability, and speed of response before reaching a steady state.
Dynamic policy – It is a set of rules or decision logic which changes in real-time based on current context, environment signals, or shifting risks. Unlike static rules which stay the same after a one-time approval, a dynamic policy continuously evaluates live data like user location, device security, or behaviour.
Dynamic positioning – It is frequently called dynamic beam positioning. It refers to the use of computer-controlled systems to automatically steer and adjust the energy source, very frequently an electron or laser beam, across the surface of a material during high-precision processing like electron beam welding.
Dynamic power control – It is a real-time method used to adjust power levels automatically. It optimizes system performance, minimizes energy waste, and prevents overloads across different engineering fields.
Dynamic power dissipation – It is the energy consumed by a digital CMOS (complementary metal-oxide semi-conductor) circuit when its transistors switch states. It happens during the charging and discharging of load capacitances and brief short-circuit currents during signal transitions, making it a primary source of heat and power consumption in active microprocessors.
Dynamic pressure – It is defined as the pressure developed by the forward motion of a body in a compressible air flow, which is related to the true airspeed of the body.
Dynamic pressure transducer – It is a specialized sensor which converts rapid, time-varying pressure fluctuations into electrical signals. Unlike static sensors which measure steady or slow-moving pressure, it captures fast transient events like shock-waves, engine combustion, and turbulence within milli-seconds or micro-seconds.
Dynamic processes – These typically refer to two distinct but related concepts namely dynamic metallurgical mechanisms (microstructural changes occurring during metal deformation) and metallurgical process dynamics (the real-time changes, control, and chemical kinetics within industrial furnaces and reactors).
Dynamic programming – It is a technique for optimization of the solution of a problem by combining solutions to smaller sub-problems. It is mainly used to optimize recursive algorithms by storing the results of sub-problems so that each sub-problem is solved exactly once, eliminating redundant calculations.
Dynamic programming method – It is a mathematical optimization and computer programming approach which simplifies complex problems by breaking them down into smaller sub-problems, allowing for efficient optimization and control of systems, particularly in applications with non-linear objective functions and constraints.
Dynamic programming principle – Dynamic programming is based on the Bellman’s principle of optimality, which states that an optimal sequence of decisions has the property which whatever the initial state and first decision are, the remaining decisions are to constitute an optimal policy with respect to the state resulting from the first decision. In simpler terms, an optimal solution to the main problem is built directly from the optimal solutions of its sub-problems.
Dynamic property – It is a feature in programming and data management where an attribute or field is added to an object, class, or data structure at run-time instead of being hard-coded during compilation. This allows programmes to handle changing data and flexible user inputs on the fly.
Dynamic pump – It is a type of velocity pump which uses kinetic energy to move fluids. It spins an internal impeller or rotor to speed up the liquid. It then changes that high speed into pressure to push the fluid through a pipe.
Dynamic random-access memory – It is a type of volatile memory which stores each bit of data in a separate capacitor, needing periodic refresh to maintain the information because of the capacitor charge leakage. It is mainly used as the main memory in most computers.
Dynamic range – It is the measure of the difference between the absolute loudest and quietest, or brightest and darkest, parts of a signal. In photography and video, it is the span of light a camera can record from deep shadow to bright highlight. In audio, it is the volume gap between a whisper and a loud crash.
Dynamic reconfiguration – It is the process of changing a system’s software, hardware, or network structure while it is still running. It allows users to add, update, or remove components without shutting down the system or stopping ongoing tasks.
Dynamic recovery – it is a process occurring in hot working of metals in which a fine sub-grain structure forms within the elongated grains because of the annihilation of dislocations due to easy cross slip and climb. It results in a lowering of the flow stress. Dynamic recovery, as opposed to dynamic recrystallization which occurs in hot working, occurs in metals of high stacking fault energy such as aluminum, alpha-iron, and majority of the body centred cubic metals.
Dynamic recrystallization – It is a type of recrystallization process, found within the fields of metallurgy and geology. In dynamic recrystallization, as opposed to static recrystallization, the nucleation and growth of new grains occurs during deformation rather than afterwards as part of a separate heat treatment. The reduction of grain size increases the risk of grain boundary sliding at elevated temperatures, while also decreasing dislocation mobility within the material. The new grains are less strained, causing a decrease in the hardening of a material. Dynamic recrystallization allows for new grain sizes and orientation, which can prevent crack propagation. Rather than strain causing the material to fracture, strain can initiate the growth of a new grain, consuming atoms from neighboring pre-existing grains. After dynamic recrystallization, the ductility of the material increases.
Dynamic recrystallization-controlled rolling – It is a hot-metalworking technique where new, strain-free grains nucleate and grow while the metal is being deformed. Unlike traditional rolling, which relies on static recrystallization between passes, dynamic recrystallization (DRX) refines the micro-structure during the actual rolling pass, creating highly uniform, ultra-fine grains.
Dynamic recrystallized structure – It refers to the micro-structure of a metal or alloy which has undergone the nucleation and growth of new, strain-free grains during high-temperature plastic deformation (e.g., hot rolling, forging). It replaces a highly stressed, defect-heavy structure with refined, equiaxed grains.
Dynamic regime – It refers to distinct periods within a time series which display varying behaviours, such as low and high volatility, identified through flexible modelling methods, which allows for the determination of both the number and nature of these regimes.
Dynamic reserve – It refers to a variable buffer, capacity, or storage metric which adjusts continuously based on real-time conditions, probabilistic forecasting, or system stress rather than remaining fixed.
Dynamic resistance – It is the opposition a non-linear electronic component offers to a small AC (alternating current) or changing signal at a specific operating point. It equals the change in voltage divided by the change in current (dV/dI), shown as the inverse slope of a voltage-current (V-I) curve.
Dynamic response – It is how a system, structure, or machine changes and reacts over time when an external force, load, or input is applied. Instead of looking at a constant or fixed state, it tracks real-time variations like movement, speed, and stability.
Dynamic scanning calorimetry – It is a thermo-analytical technique which measures the difference in heat flow required to increase the temperature of a sample and a reference as a function of time and temperature under a controlled temperature programme.
Dynamic scenario – It is a set of rules and changing variables used in computer models or business plans. It updates automatically as new real-time data or user choices come in. This helps systems or leaders test different future events.
Dynamic seal – It is a seal which has rotating, oscillating, or reciprocating motion between its components, as opposed to stationary-type seal such as a gasket.
Dynamic shear stress – It is the internal frictional force per unit area which develops within a moving or flowing fluid. It equals the product of the fluid’s dynamic viscosity (mu) and the velocity gradient (du/dy) perpendicular to the flow direction ‘t = mu x du/dy’. Alternatively, dynamic yield shear stress refers to the minimum stress needed to keep a structured fluid flowing once movement has already started.
Dynamic shear test – It evaluates how a material responds to cyclic or rapid twisting and shearing forces. It measures properties like stiffness and elasticity under repeating loads.
Dynamic similarity – It is a relation between two different systems, such as a small model and a full-size vehicle or pipe, where the ratios of all corresponding forces (like friction, gravity, and inertia) are identical. This happens when key dimensionless numbers, such as the Reynolds number or Froude number, are equal in both systems.
Dynamic simulation browser – It is a hierarchical interface panel in 3D CAD (computer aided design) and mechanical simulation software which displays a structured, nested list of a model’s physical attributes, moving components, and assembly parameters.
Dynamic simulation code – It is a set of programmed instructions which uses numerical integration to compute how a system’s state variables, such as position, velocity, or pressure, change over time in response to internal rules and external forces.
Dynamic simulation environment – It is a computer-based virtual platform which models how a system changes, reacts, and evolves over time. Unlike static or steady-state tools that look at fixed conditions, it uses mathematical equations and physical laws to track moving parts, changing forces, and shifting energy levels.
Dynamics of a mechanism – It is the study of how forces, torques, and accelerations interact within interconnected rigid bodies to produce and control motion. It merges system geometry with external loads to predict real-world machine behaviour.
Dynamic soil properties – Soil dynamics deals with engineering properties and behaviour of soil under dynamic stress. For the dynamic analysis of equipment foundations, soil properties, such as Poisson’s ratio, dynamic shear modulus, soil density, and damping of soil, are normally needed. Satisfactory design of an equipment foundation needs information on soil profile, depth of different layers, physical properties of soil, and ground water level. This information can be obtained by normal sub-surface exploration techniques. In addition, it is necessary to determine dynamic shear modulus, material damping, poisons ratio and mass density of soil for dynamic analysis of the equipment foundation. Dynamic shear modulus of a soil is normally determined from laboratory or field tests. Material damping can be determined from vibration tests on soil columns in the laboratory. The values of dynamic shear modulus and damping can be estimated from empirical estimations for preliminary design purposes. The soil characteristics needed in analysis of foundation are (i) shear modulus, (ii) Poisson’s ratio, (iii) damping of soil, (iv) soil density, and (v) allowable soil pressure.
Dynamic spectrum access – It is a wireless communication technique which allows radios and networks to use frequency bands dynamically. It improves efficiency by letting secondary users share or use unused licensed spectrum (white spaces) when primary owners are inactive, avoiding interference across time, space, and frequency.
Dynamic spectrum management – It is the real-time adaptive allocation and optimization of radio frequency spectrum resources. By adjusting to changing traffic demands and network conditions, dynamic spectrum management (DSM) improves communication efficiency, minimizes signal interference, and maximizes overall network capacity.
Dynamic splice strength – It is also called splice fatigue strength. It refers to the ability of a splice joint to withstand repeated loads over time without failure. It is essentially the splice’s resistance to fatigue, which is the gradual weakening of a material because of repeated stress.
Dynamic splice test – It assesses the fatigue strength and endurance of a splice (joint) under simulated operational conditions, which involve fluctuating loads and repeated bending. This test helps determine the splice’s ability to withstand long-term stresses and vibrations normally experienced by conveyor belts and other similar systems. The test typically involves applying cyclic loading to the splice, simulating the dynamic forces it encounters during operation, and measuring how many load cycles the splice can withstand before failing.
Dynamic stability – It is a system’s or object’s ability to regain its original state of balance over time after being disturbed by an outside force. While static stability looks only at the immediate reaction, dynamic stability tracks how the object behaves through continuous motion and time.
Dynamic start / stop control – It is a control system which is managing the gradual starting and stopping of the conveyor, needing regular adjustments for optimal performance and reduced wear.
Dynamic stiffness – It is the frequency-dependent ratio of a dynamic force to the resulting dynamic displacement ‘x’. Unlike static stiffness, which measures resistance to constant loads, dynamic stiffness characterizes how a material or structure deforms under constantly changing, cyclic forces during vibration or operational use.
Dynamic strain aging – It is a behaviour in metals in which solute atoms are sufficiently mobile to move toward and interact with dislocations. This results in strengthening over a specific range of high temperature and strain rate.
Dynamic stress – It is the internal resistance force per unit area which develops within a material when it is subjected to rapidly changing, fluctuating, or time-dependent loads, such as vibrations, oscillations, or moving forces. Unlike static stress, it accounts for structural inertia, acceleration, and damping effects.
Dynamic structure – It is an arrangement or system which can change, grow, shrink, or adapt in real-time while it is running or in use, rather than staying fixed and rigid. Depending on the field, it refers to computer memory allocation, physical architecture, or organizational set-ups.
Dynamic sub-system – It is a component within a system whose behaviour changes over time based on external factors or inputs.
Dynamic switching – It is a method where a system changes its operational pathways, rules, or configurations in real time based on live conditions. Instead of using a fixed or static set-up, the system adapts instantly to manage workloads, traffic loads, or performance needs.
Dynamic systems development method – The dynamic systems development method is one of the agile product development methodologies. Like other members of the agile family, it conducts development in a series of iterations, with user-story-based improvements made in increments. The dynamic systems development method operates with fixed cost and time constraints and uses the MoSCoW (a prioritization technique) prioritization method to identify the desired product requirements with these constraints in mind.
Dynamic tests – These refer to assessments which evaluate the mechanical properties of materials, such as skin, under varying frequencies and amplitudes, incorporating methods like indentation, torsion, and tension to analyze behaviour across a wide frequency range. These tests are used to study properties such as stiffness and damping coefficients, and to investigate changes due to factors like aging.
Dynamic testing – It is a software testing method which involves executing an application or programme to check its runtime behaviour, performance, and functionality. By feeding the software input data and comparing the actual output to expected results, it helps find bugs and errors that cannot be detected by just reading the source code.
Dynamic trade – It normally refers to economic activities or financial strategies which change and adapt over time rather than remaining fixed. In economics, it frequently highlights long-term growth and productivity changes from international commerce, while in finance, it describes adjusting positions continuously based on real-time market data.
Dynamic transformation – it is a phase change which occurs while a metal or alloy is undergoing active plastic deformation (such as hot rolling or forging). Unlike traditional phase changes driven entirely by temperature, applied mechanical stress and strain considerably lower the energy barriers needed for the transformation.
Dynamic trim – It very frequently refers to a real-time video editing technique used to adjust clip edit points during play back, or an automated engineering system that optimizes a vessel’s angle in the water or a dynamic system’s equilibrium state.
Dynamic viscosity – It is the bulk property of a fluid, semi-fluid, or semi-solid substance which causes it to resist flow.
Dynamic voltage and frequency scaling – It is a power-management technique which adjusts a processor’s voltage and clock frequency in real time based on work-load demands. It saves energy during low-activity periods by exploiting the rule that dynamic power consumption scales linearly with frequency but quadratically with voltage.
Dynamic voltage restorer – It is a power electronic device connected in series with a distribution grid to protect sensitive loads from voltage problems like sags, swells, and unbalances. It works by rapidly injecting missing compensatory voltage into the system.
Dynamic weighing system – It is a system integrated into the conveyor for real-time measurement of material weight during transit, demanding regular calibrations for accuracy.
Dynamometer – It is a device for simultaneously measuring the torque and rotational speed (revolution per minute) of an engine, motor or other rotating prime mover so that its instantaneous power can be calculated.
Dynamometer card – It is also called a dyna-graph card. It is a graphical plot of load against position for one complete stroke of an oilfield sucker-rod pumping system. It serves as a core diagnostic tool used by engineers to evaluate mechanical performance and downhole operating conditions.
Dyne liquids – These liquids refer to solutions made from a mixture of two chemicals which produce liquids with surface tension in the range of 30 dynes per centimeter to 70 dynes per centimeter, normally used to estimate the treatment level of plastic surfaces in manufacturing environments. The assessment involves placing droplets on a treated surface and observing their spreading behaviour.
Dysprosium – It is a soft, silvery-white rare-earth metal of the lanthanide series. It is mainly used as a critical metallurgical additive to improve the high-temperature performance, coercivity, and corrosion resistance of high-strength permanent neodymium magnets.
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