Glossary of technical terms for the use of metallurgical engineers Terms starting with alphabet ‘E’
Glossary of technical terms for the use of metallurgical engineers
Terms starting with alphabet ‘E’
E’ – It is the storage modulus (elastic component). It represents the elastic portion of the material’s viscoelastic behaviour. It measures the energy stored by the material during a deformation cycle and released upon unloading. It is directly related to the stiffness of the elastomer. A higher E’ indicates a stiffer, more elastic material which returns quickly to its original shape. It indicates the ‘solid-like’ character of the elastomer.
E” – It is the loss modulus (viscous component). It represents the viscous portion of the material’s behaviour. It measures the energy dissipated (lost) as heat during a deformation cycle, typically because of the molecular chain friction. A higher E” indicates higher damping or energy absorption (important for applications like engine mounts or tyres). It indicates the ‘liquid-like’ character of the elastomer.
E’ and E” – E’ is the dynamic modulus of the rubber which is in phase with the applied strain loading. E” is the loss modulus, which is out of phase with the applied strain. The ratio of E”/E’ = tan delta, which is the internal friction of the rubber. E’ is an important factor for low indentation rubber. In the context of elastomers and viscoelastic materials, E’ and E” are the two components of the complex modulus E* measured through dynamic mechanical analysis (DMA). They define how a material stores and dissipates energy under dynamic stress.
E85 fuel – It is an alternative motor fuel blend nominally consisting of 85 % renewable ethanol and 15 % hydrocarbon (normally petroleum / gasoline). Since ethanol has distinct combustion properties compared to standard gasoline, E85 fuel needs specific hardware and calibration.
E85 gasoline – It is defined as a fuel mixture consisting of 85 % ethanol and 15 % gasoline, qualifying it as an alternative fuel for flexible fuel vehicles.
Earing – It is the wavy symmetrical projections formed during cupping, deep drawing, or spinning. It is the formation of ears or scalloped edges around the top of a drawn shell, resulting from the directional differences in the plastic-working properties of rolled metal, with, across, or at angles to the direction of rolling. It can also be caused by improperly adjusted tooling.
Earliest start of an activity – It is the earliest moment at which an activity can start in a programme evolution review technique (PERT) network. It is the calendar time when an event can occur when all the predecessor events are completed at the earliest possible times. Earliest start time for an activity is equal to the largest of the earliest finish times of its immediate predecessors.
Earliest finish time of an activity – It is the earliest moment at which an activity can be completed in a programme evolution review technique (PERT) network. It is the time at which an activity finishes if there are no delays in the project.
Early adopters – They refer to a small group of customers who engage with organizations in the early stages of product development, providing active feedback and insights based on real-world implementation. This relationship allows for product design adjustments which cater to specific needs while enabling the product team to iterate quickly based on early usage experiences.
Early crack growth – It refers to the initial, frequently rapid propagation phase of a fatigue crack from a flaw or material notch, typically covering sizes on the order of 0.1 millimeters. Unlike long cracks, Early crack growth (ECG) behaves according to microstructural factors and local plastic deformation, frequently growing faster than predicted by traditional linear elastic fracture mechanics.
Early decay time – It is the duration required for the sound level to decay by 10 dB in a space, reflecting the perceived reverberance and varying by location within a room. It is determined from a best fit straight line to the initial part of the sound decay curve and can indicate unique acoustic properties of the environment.
Early experience – It refers to the structured, intentional process of shaping the initial interactions, knowledge, and perspectives a person has with a product, system, or professional field to influence their long-term behaviour and success. This approach combines user-centered design with behavioural science to engineer positive, high-impact initial experiences.
Early response action – It is the initiative which is taken as soon as a potential threat or crisis is identified to manage, resolve, or prevent that threat, frequently using preventive instruments and mechanisms.
Early strength development – It refers to the rapid gain of mechanical strength (compressive strength) in materials, particularly concrete, within the first 24 hours to 7 days after placement. It enables accelerated construction schedules, such as faster formwork removal, prestressing, or opening infrastructure to traffic.
Early vision – It is the stages which involve the capture, preprocessing, and coding of visual information, excluding interpretation or other cognitive processes.
Early warning system – It is an integrated system of hazard monitoring, forecasting and prediction, disaster risk assessment, communication and preparedness activities systems and processes which enables organizational management to take timely action to reduce disaster risks in advance of hazardous events.
Ears – It is the wavy symmetrical projections formed in the course of deep drawing or spinning as a result of directional properties or anisotropy in sheet. Ears occur in groups of four or eight with the peaks of the projections located at 45-degree and / or at 0-degree and 90-degree to the rolling direction. Degree of earing is the difference between average height at the peaks and average height at the valleys, divided by average height at the valleys, multiplied by 100 and expressed in percent.
Earth connection – It is also called earthing). It is a low-resistance, conductive path connecting electrical equipment casings or system neutrals to the general mass of the earth. It establishes a zero-voltage reference point, safely discharging fault currents to protect personnel from electric shock and prevent equipment damage.
Earth construction – It is a sustainable building method using raw soil, typically subsoil, clay, sand, and aggregates, as the main structural material. It involves techniques like ramming, moulding, or pressing soil (frequently with stabilizers like lime) to create durable, high-thermal-mass, low-carbon structures.
Earthed system – It is also called grounded system. It is an electrical installation with a deliberate, low-impedance connection to the general mass of the earth. Engineered to ensure safety and operational stability, it provides a safe path for fault currents, stabilizes voltage levels, and triggers protection devices during insulation failures.
Earth electrode – It is a metal conductor buried directly in the soil to provide a low-resistance path between an electrical system and the earth, important for safety and system stability. It dissipates fault currents, lightning strikes, and leakage currents into the ground, limiting shock hazards and ensuring protective device operation.
Earth fault – It is also called ground fault. It is an unintentional, low-impedance connection between a live conductor and the earth, ground, or metallic parts connected to earth. It causes a leakage current to flow outside its normal circuit, potentially resulting in equipment damage, insulation failure, or dangerous electrical shocks.
Earth fault conditions – These conditions refer to situations where there is an unintended connection between a live electrical conductor and the earth, leading to the flow of fault current. This condition triggers protective mechanisms such as the earth leakage relay to ensure safety and prevent equipment damage.
Earth fault protection – It is an important safety system designed to detect unintended electrical connections between live conductors and the ground (earth). By identifying leakage currents from insulation failures, moisture, or damage, the system instantly isolates the circuit to prevent equipment damage, fire hazards, and fatal electric shocks.
Earth fault relay – It is a protective device which detects low-level leakage current flowing from a live conductor to ground, caused by insulation failure or damage. It operates by measuring current imbalances, frequently through a ‘core balance current transformer’ (CBCT), to trip a circuit breaker and isolate the faulty circuit before it causes fire or electric shock.
Earth fill dam – It is a hydraulic barrier constructed by compacting layers of natural soil, clay, sand, or rock, designed to impound water for storage, flood control, or hydropower. It is categorized as an embankment dam where compacted materials account for over 50 % of the volume, utilizing an impervious core to control seepage.
Earthing – It is also called grounding. It is the process of safely transferring immediate discharge of electrical energy directly to the earth using a low-resistance wire. It acts as a protective system, connecting non-current carrying metallic parts of equipment to the ground to prevent electric shocks, fires, and equipment damage from leakage currents or surges.
Earthing transformer – It is also called grounding transformer. It provides a low-impedance path to ground, creating an artificial neutral point for delta-connected electrical systems (3-phase, 3-wire). It prevents high over-voltages during ground faults, improves protection safety, and is typically engineered using a zig-zag or star-delta configuration, frequently rated for short-time duty (e.g., 30 seconds to 60 seconds) to handle high fault currents.
Earth-moving equipments – These are large, rugged build, high performance machines which can handle a wide range of repetitive, labour-intensive construction tasks with efficiency, speed and precision. These machines enable efficient transportation of large quantities of soil, rock, and other materials. A range of heavy machinery is used for the excavation, transportation, and placement of earth materials on the construction sites. This equipment is designed to handle a variety of tasks, from digging trenches and excavating foundations to grading roads and hauling materials across rugged terrain.
Earth observation – It is the use of active or passive sensors to collect data about different targets on Earth, including the atmosphere, surface, and subsurface layers. It typically involves monitoring changes in spectra resulting from the interaction of solar or terrestrial sources with these targets.
Earth observation mission – It is the systematic process of gathering information about earth’s physical, chemical, and biological systems through remote sensing technologies to monitor and assess natural and human-made environments. It involves defining needs for sensors, platforms, and data processing to study systems like the atmosphere, oceans, and land.
Earth observation system – It is an engineered, integrated framework using active or passive sensors to collect, process, and analyze data about earth’s surface, atmosphere, and oceans, mainly through space-borne, air-borne, or ground-based platforms. It supports environmental monitoring, disaster management, and commercial applications through timely and accurate geospatial intelligence.
Earth pin – It is also called grounding pin. It is the third, typically longer and thicker, prong on a 3-pin plug designed to provide a low-resistance path to the earth for electrical leakage, protecting users from electric shocks. It connects the metal casing of an appliance to the ground system, ensuring safety by diverting fault current.
Earth pressure cell – It is a geotechnical sensor used to measure the total pressure, stress, or load exerted by soil and fill materials on structures like retaining walls, dams, and tunnel linings. They typically consist of two welded stainless-steel plates filled with fluid, creating a pressure transducer which converts soil stress into an electrical signal, enabling verification of design assumptions.
Earthquake – It is a violent and abrupt shaking of the ground, caused by movement between tectonic plates along a fault line in the earth’s crust. Earthquake can result in the ground shaking, soil liquefaction, landslides, fissures, avalanches, fires and tsunamis. It can strike suddenly and without warning. The extent of destruction and harm caused by an earthquake depends on magnitude, intensity and duration, local geology, time of day that it occurs, building and industrial plant design and materials, and the risk-management measures put in place. Earthquake intensity is measured using the ‘modified Mercalli intensity (MMI) scale and earthquake magnitude is measured using the Richter scale and other magnitude scales.
Earthquake engineering – It is an inter-disciplinary branch of engineering which designs and analyzes structures, such as buildings and bridges, with earth-quakes in mind. Its overall goal is to make such structures more resistant to earth-quakes. An earth-quake (or seismic) engineer aims to construct structures which does not get damaged in minor shaking and avoids serious damage or collapse in a major earth-quake. A properly engineered structure does not necessarily have to be extremely strong or expensive. It has to be properly designed to withstand the seismic effects while sustaining an acceptable level of damage.
Earthquake input energy – It is the total work done by the foundation force (base shear) on a structure because of the seismic ground motion, representing the total seismic energy transferred to the building. It is a cumulative measure used in energy-based seismic design, composed of kinetic energy, elastic strain energy, viscous damping energy, and hysteretic (damage) energy.
Earthquake load – It is also called seismic load. It is the dynamic, inertial force applied to a structure during ground shaking, representing the acceleration of the building’s mass rather than direct external pressure. It is a vital, non-stationary dynamic load calculated based on local hazard, soil, and building characteristics to ensure structural integrity and prevent collapse.
Earthquake loading – It is also called seismic loading. It is the application of earthquake-generated, dynamic forces (ground acceleration) onto a structure, causing it to vibrate and experience inertial forces. It acts at the contact surfaces between the ground and the building, mainly demanding lateral force resistance based on the structure’s mass, stiffness, and site-specific seismic hazard.
Earthquake-resistant structures – These structures are designed to protect buildings to some or greater extent from earth-quakes. While no structure can be entirely impervious to earth-quake damage, the goal of earth-quake engineering is to erect structures which fare better during seismic activity than their conventional counter-parts. As per the building codes, earth-quake-resistant structures are intended to withstand the largest earth-quake of a certain probability which is likely to occur at their location. This means the loss of life is to be minimized by preventing collapse of the buildings for rare earth-quakes while the loss of the functionality is to be limited for more frequent ones.
Earth’s core – It is the innermost, densest layer of the planet, situated below the mantle at a depth of around 2,900 kilo-meters. Composed mainly of iron and nickel, this metallic sphere is divided into two distinct regions based on physical state, playing an important role in thermal evolution and generating the planetary magnetic field.
Earth’s radiation belts – These refer to regions captured by earth’s magnetic field which contain high strength charged particles, predominantly electrons and protons, with energy ranges of 0.0004 mega electron volt (MeV) to 7 mega electron volt for electrons and 0.1 mega electron volt to 400 mega electron volt for protons. These belts are divided into inner and outer sections, located around 600 kilo-meters to 10,000 kilo-meters and 10,000 kilo-meters to 60,000 kilo-meters above the equator, respectively.
Earth voltage – It is also called earthing voltage. It is the electrical potential difference between an electrical installation’s grounding system and the remote, neutral ‘reference earth’. It indicates potential rise, frequently during faults relative to 0V (zero volt) ground. It is important for electrical safety, with common types being touch, step, and surface potentials.
Earth wire – It is a low-resistance conductor which creates a direct electrical connection between an electrical device’s metallic chassis and the physical earth (ground). Its purpose is to safely channel fault currents to the ground, triggering protective devices (fuses / breakers) to prevent electrical shock or fire.
Earth-works – These are engineering works created through the processing of parts of the earth’s surface involving quantities of soil or unformed rock. Earth-works are carried out in and with granular soils, i.e. the movement of earth by means of excavation and filling.
Ease of use – It is the measure of a system, product, or process’s simplicity, needing minimal mental and physical effort to achieve tasks efficiently. It focuses on user-centric, objective, and measurable metrics, such as time to complete tasks, error rates, and learnability, rather than subjective, vague impressions of friendliness.
Easily extruded alloys – These are materials, very frequently aluminum alloys, which show high plasticity and low resistance to deformation when heated, allowing them to be forced through a die at high speeds (up to or exceeding 100 meters per minute). These alloys are characterized by their ability to form complex, intricate, or hollow cross-sections with excellent surface finishes without needing extreme pressures.
Easy axis – It is the crystallographically preferred direction of spontaneous magnetization in a ferro-magnetic material, needing the lowest applied magnetic field to reach saturation. It represents an energetically favourable, stable orientation for magnetic moments, distinct from the hard axis, which needs high energy to magnetize.
Eaves – These are the edges of a roof that project horizontally beyond the side of a building’s wall. They function as a protective overhang designed to shed rainwater away from walls, shielding foundations and siding from water damage, while also offering shade. Eaves frequently house gutters, soffits, and ventilation systems.
Ebonite – It is a hard rubber product got through the prolonged vulcanization of rubber with high proportions of sulphur, characterized by toughness, chemical resistance, ease of machining, glossiness, and excellent electrical resistance. It is a rigid, non-resilient material produced by extensively vulcanizing natural rubber with high quantities of sulphur (25 % to 80 %).
Eccentric – It is the offset portion of the drive-shaft which governs the stroke or distance the cross-head moves on a mechanical or manual shear.
Eccentric annulus – It is a non-uniform ring-shaped space formed between two cylinders (such as a pipe inside a hole or another tube) where the central axes of the inner and outer cylinders do not coincide. This offset creates a crescent-shaped, uneven gap with varying thickness, rather than a uniform annulus.
Eccentric anomaly – It is the angle between the first axis of an ellipse and a point on the auxiliary circle of radius equal to the semi-major axis, used to describe the position of a point in elliptical motion.
Eccentric bottom tapping – It takes place since the taphole is placed in the furnace bottom and closer to a side of the furnace. It permits controlled interruption of the tapping process by tilting the electric arc furnace in order to retain slag or liquid steel in the hearth. It leads to slag-free tapping, and shorter tap-to-tap times. It also reduces refractory and electrode consumption, and improves ladle life.
Eccentric-driven mechanical press – It is also known as a crank press or eccentric press. It is a type of mechanical press which uses an eccentric mechanism to convert rotary motion into linear motion, enabling it to exert force on a workpiece. It is characterized by its high operating speed and is normally used for short-run jobs like punching and stamping.
Eccentric forging press – It is a mechanical machine press which uses an eccentric shaft or cam to convert rotational motor power into linear motion to move a ram. It delivers high-pressure, squeezing force (rather than impact) at low speeds, typically for closed-die forging, punching, or stamping operations
Eccentric gear – It is a main press-drive gear with an eccentric(s) as an integral part. The unit rotates about a common shaft, with the eccentric transmitting the rotary motion of the gear into the vertical motion of the slide through a connection.
Eccentricity – It is the deviation from a common centre as, e.g., the inner and outer walls of a round tube. It is the difference between the mean wall thickness and minimum or maximum wall thickness at any one cross section. The permissible degree of eccentricity can be expressed by a plus and minus wall-thickness tolerance. In journal bearings, it is the radial displacement of the journal centre from the centre of the bearing liner.
Eccentricity degree – It is the extent of deviation of a pulley’s centre from its true axis, demanding routine assessments to maintain alignment and prevent misalignment issues for sustained smooth operation.
Eccentricity vector – It is a dimensionless vector in orbital mechanics pointing from the centre of attraction to periapsis (closest approach), with a magnitude equal to the orbit’s scalar eccentricity, representing the shape and orientation of an elliptical orbit. It is a constant of motion for Keplerian orbits. It is also known as the Runge-Lenz vector.
Eccentric load – It refers to a load applied off-centre to a structural element, leading to a combination of axial and bending stresses which can influence the failure mechanisms of materials, such as compressive failure in concrete and tensile yield in reinforcement. This off-centre application causes a combination of axial force (compression or tension) and bending stress, creating an additional bending moment.
Eccentric mechanism – It is a mechanical device which converts rotary motion into reciprocating motion by using a rotating disk or cylinder (the eccentric) whose centre is offset from the axis of rotation. This offset, or eccentricity, creates a changing distance between the rotating part and a fixed point, resulting in a linear back-and-forth movement.
Eccentric press – It is a type of mechanical press, frequently called a crank press, which utilizes a rotating eccentric shaft to convert rotational motion into linear motion, which is then used for operations like punching, stamping, and forming metal. It is characterized by its high speed and suitability for serial production.
Eccentricity ratio – In a bearing, it is the ratio of the eccentricity to the radial clearance.
Eccentric reducer – It is an asymmetrical pipe fitting used to connect two pipes of different diameters, characterized by having one side flat (parallel to the flow) while the other is tapered, resulting in offset centre-lines. Mainly used in horizontal piping, this design maintains a constant top or bottom elevation, preventing air pockets and aiding drainage.
Eccentric shaft – It is a mechanical component featuring a crank or bearing section offset from its central axis of rotation. It converts rotational movement into linear reciprocating motion, commonly used in machinery like pumps, engine valve trains, and industrial presses, frequently producing an approximation of simple harmonic motion.
Eccentric upsets – It refers to a specific type of forging defect or, in specialized cases, a purposeful forging technique where the metal is compressed unevenly or off-centre, leading to an asymmetrical distribution of material.
Echo cancellation – It is a digital signal processing technique which removes unwanted echoes from audio signals by identifying the echo signal, generated by acoustic coupling between speakers and microphones or electrical impedance mismatches, and subtracting it from the received signal. It utilizes adaptive filters to model the echo path and ensure high-quality, real-time audio.
Echo effect – It is a technique involving a delayed, attenuated repetition of a signal, audio or electro-magnetic, added to the original to create a distinct, repeating sound or reflection. It is used in acoustics to simulate spatial depth and in telecommunications to manage signal reflections caused by impedance mismatches.
Echo intensity – It is the amplitude of acoustic signals reflected from an interface, mainly influenced by the difference in acoustic impedance between materials. It represents the brightness of a returned signal in imaging (B-mode ultrasound) or non-destructive testing, used to detect defects, identify materials, or measure structural characteristics.
Echo method – It is a non-destructive testing (NDT) technique which identifies internal flaws or measures material thickness by emitting pulses (ultrasonic or mechanical) and analyzing the reflections, or ‘echoes’ which return from boundaries, defects, or the back wall. Key variations include pulse-echo ultrasonic testing and impact-echo for concrete.
Echo path – It refers to the physical and electrical route which a signal travels after being reflected or leaked back toward its source. It is a critical concept in telecommunications and audio engineering for designing echo cancellation systems.
Echo power – It normally refers to the intensity or magnitude of a reflected signal (acoustic, radar, or laser) which returns to the receiver after interacting with a target or boundary. It is a critical metric for determining the distance, size, and nature of the reflecting object, frequently calculated based on acoustic impedance or signal backscattering.
Echo, pulse – It is a non-destructive testing (NDT) or measurement method where a single transducer emits a short burst of high-frequency energy (ultrasonic, acoustic, or electro-magnetic) and then listens for the reflection, or ‘echo’, of that pulse from within a material. It is widely used to detect internal flaws, measure thickness, or determine the distance to a target based on the time it takes for the signal to return.
Echo signal – It is a reflected wave (acoustic, electro-magnetic (radio / laser), or electrical) which returns to its source or a receiver after impacting an object, with a measurable delay. It is a delayed, attenuated, and typically distorted replica of the original transmitted signal.
Echo-sounder method – The most successful water level measurement method is the non-contacting echo-sounder method. A sound signal is transmitted from a sound generator located above the water level which, after it is reflected from the water surface, is received. The distance between the transmitter / receiver and the water level (i.e. the headwater level) is calculated from the transit time of the sound wave. The sound velocity however is a function of the composition of the elements in the sound path, including temperature and humidity which can vary. A reference path, which is precisely defined mechanically, can be used to compensate for these disturbance factors. A cone is installed at the sensor to protect against external influences, e.g. rain fall and to shield against undesirable wall reflections. The connected transmitter includes a microprocessor which uses stored curves for different flume meters to calculate the flow rate proportional 0/4-20 milli ampere output signal. Naturally such transmitters provide self-monitoring functions, alarm contacts and volume totalizers.
Echo strength – It is the intensity or amplitude of a reflected sound or electro-magnetic wave returning to a receiver, normally measured in decibels (dB). It represents the ability of a target to reflect energy, dictated by acoustic impedance differences, target size, shape, and material properties.
Eckert number (Ec) – It is a dimensionless parameter in fluid mechanics and heat transfer, defining the ratio of a flow’s kinetic energy to its enthalpy difference (thermal energy). Used in high-speed flow analysis, it characterizes viscous dissipation and determines if frictional heating effects can be ignored (Ec is below 1) or are important.
Eco benefit – It is a positive outcome for the natural environment, such as reduced pollution, improved biodiversity, or resource conservation, resulting from specific actions, projects, or products. These benefits represent the ‘unburdening’ of nature by reducing negative impacts, frequently achieved through efficiency, recycling, or using sustainable alternatives.
Eco-costs – These are the virtual, estimated costs needed to prevent the environmental damage (pollution and resource depletion) caused by a product or service. Represented in monetary units, they represent the necessary investment to keep a product’s life cycle within the earth’s carrying capacity.
Eco-efficiency – It is a management strategy which creates more value (goods / services) with less environmental impact (waste / pollution / resources). It pairs operational excellence with environmental responsibility, aiming for ‘more with less’ to ensure that production, consumption, and economic growth stay within the earth’s carrying capacity.
Eco-efficiency analysis – It is a management tool which evaluates products or processes by linking environmental impacts with economic value, aiming to create more goods and services while using fewer resources and reducing pollution. It compares the total life cycle, from raw materials to disposal, to identify options which provide maximum customer benefit at the lowest cost and environmental burden.
Ecofining process – It is a two-stage hydro-processing technology which converts renewable feedstocks (waste oils, fats, and greases) into high-quality renewable diesel and sustainable aviation fuel (SAF). It achieves 85 % to 95 % yields by removing oxygen from feedstocks, enabling up to 80 % lower greenhouse gas emissions compared to fossil fuels.
Eco-indicators – These are standardized metrics used to assess the environmental impact of products, processes, or services across their entire life cycle, condensing complex ecological data into a single, actionable score. They are mainly used in design and management to identify areas for environmental improvement, covering factors such as human health, ecosystem quality, and resource depletion.
Ecoinvent database – It is a globally recognized, comprehensive repository providing peer-reviewed, transparent, and quality-assured life cycle inventory (LCI) data for environmental assessments. It contains over 26,000 datasets covering raw materials, energy, and industrial processes, allowing engineers to calculate environmental impacts and conduct ‘life cycle assessment’ (LCA).
Ecology – It is the relationships among living organisms and their environment. Ecology considers organisms at the individual, population, community, ecosystem, and biosphere levels.
Ecological balance – It is a state of balance in an ecosystem where species interact with each other and their environment in a sustainable way. It is a dynamic equilibrium which is maintained through the interplay of opposing forces.
Ecological design – It is also called eco design. It is a systematic approach to product development which integrates environmental, safety, and sustainability considerations into every phase of a product’s lifecycle, from material extraction and manufacturing to use and final disposal. Its main goal is to minimize negative environmental impacts while maintaining functionality, quality, and economic efficiency.
Ecological disturbance – It is a discrete event in time which disrupts an ecosystem, community, or population structure. These events alter resource availability, substrate, or the physical environment, and can either harm the ecosystem or create necessary opportunities for new growth and bio-diversity.
Ecological equilibrium – It refers to a state of dynamic balance within an ecosystem where genetic, species, and ecosystem diversity remain relatively stable, subject to gradual changes through natural succession. It is another term for ecological balance.
Ecological footprint – It is a measure of human demand on the ecosystem. It compares human consumption of natural resources with the planet’s ecological capacity to regenerate them.
Ecological footprint analysis – It is an engineering and environmental accounting tool which measures the biologically productive land and water area needed to produce the resources a human population consumes and to assimilate its waste, using technology and resource management practices. It translates consumption into a standardized ‘global hectare’ (gha) of productive land, enabling a ‘demand against supply’ comparison with nature’s regenerative capacity.
Ecological impact – It is the effects left on organisms and their environment because of the actions made by humans and natural occurrences. These changes can be beneficial or adverse to the ecosystem.
Ecological integrity – It is the biological diversity, ecological processes and structure found in healthy ecosystems. An ecosystem shows integrity if, when it is subjected to stress, it is able to sustain a state that allows that ecosystem to thrive.
Ecological resilience – It is the ability of a system to absorb impacts before a threshold is reached where the system changes into a different state is known as ecological resilience.
E-commerce – It is also called electronic commerce. It refers to the buying and selling of goods and services over the internet or through electronic networks. It encompasses a wide range of online marketing activities, including online shopping, digital payments, and internet banking. E-commerce facilitates the exchange of goods, services, or information between organizations and customers, or between organizations themselves, using digital platforms like websites and mobile applications.
Economical design – It is the process of creating technical solutions which balance safety, performance, and functionality with minimum cost and resource waste. It involves optimizing material selection, production methods, and lifecycles to achieve the best return on investment without over-designing or sacrificing quality.
Economic analysis – It is the systematic evaluation of costs, benefits, and risks associated with decisions, policies, or projects to optimize resource allocation. It involves using economic theories, data, and quantitative models to assess the efficiency and impact of alternatives, typically aiming to maximize welfare or profit.
Economic assessment – It is a systematic evaluation which identifies, measures, and compares the costs and benefits of a policy, project, programme, or investment. It determines financial viability by weighing inputs against outcomes, frequently assigning monetary value to non-market goods to inform decision-making.
Economic asset – It is an entity from which the owner can derive a benefit or series of benefits in future accounting periods by holding or using the entity over a period of time, or from which the owner has derived a benefit in past periods and is still receiving a benefit in the current period. Since it represents a stock of future benefits, an economic asset can be regarded as a store of value.
Economic dispatch – It is the process of determining the most cost-effective, optimal, and reliable generation levels for power units to meet a specific energy demand. Its main goal is to minimize total fuel and operating costs while adhering to system constraints, such as generation limits and transmission capacity.
Economic efficiency – It refers to maximizing the value of output (products / services) while minimizing the cost of inputs (resources, labour, and capital). It involves producing goods at the lowest possible cost, ensuring no resources are wasted, and making decisions which maximize net benefits, frequently by choosing the best technical solution which is also cost-effective.
Economic equation – It is a mathematical model used to analyze the financial viability, cost-effectiveness, and efficiency of engineering projects or designs. These equations enable decision-making by quantifying factors like time value of money, depreciation, and rate of return, bridging technical design with financial reality.
Economic feasibility – It is the assessment of a project’s financial viability, determining if expected benefits (revenue, savings) outweigh costs (capital, operating) over its lifespan. It evaluates whether a technical solution is worth the investment, considering return on investment (ROI), market conditions, and risk.
Economic input-output life-cycle assessment – It is a top-down methodology which estimates the environmental impacts (emissions, energy use) of a product or service by linking economic transactions between industry sectors to environmental data. It calculates the supply-chain impacts based on monetary input, bypassing the need for detailed, boundary-restricted inventory data.
Economic instruments – These are market-based instruments. These are policies, programmes, or initiatives which provide financial motivation to achieve environmental and resource management objectives. Economic instruments encourage organizations and / or individuals to undertake several projects which are in the organizational interests and which collectively meet policy goals.
Economic model predictive control – It is an advanced control strategy which optimizes a system’s operating costs or profitability directly, rather than tracking a predefined setpoint. By using a dynamic model to predict behaviour, economic model predictive control (EMPC) adjusts control actions to maximize economic efficiency or minimize resource usage in real-time.
Economic order quantity – It represents the most favorable quantity to be ordered each time fresh orders are placed. The quantity to be ordered is called economic order quantity because the purchase of this size of material is most economical. It is helpful to determine in advance as to how much should one buy when the stock level reaches the order level. If large quantities arc purchased, the carrying costs would be large. On the other hand, if small quantities are purchased at frequent intervals the ordering costs would be high. The economic order quantity is fixed at such a level so as to minimize the cost of ordering as well the cost of carrying the stock. It is the size of the order which produces the lowest cost of material ordered.
Economic profit – It is the difference between an organization’s total revenue and the sum of its explicit costs (direct expenses like wages) and implicit costs (opportunity costs). It represents true profitability by accounting for the value of resources sacrificed to pursue a specific project, rather than just monetary expenses.
Economics – It refers to the technical and financial evaluation of methods used to extract, refine, and process metals from their ores at the lowest possible cost, highest efficiency, and maximum value-addition. It involves analyzing the entire lifecycle of metal production, from mining to final product, to ensure economic viability (i.e., that the project yields returns on investment).
Economics of power generation – It is the study of optimizing the cost of producing electricity, focusing on minimizing the cost per kilowatt-hour while maintaining reliable service. It involves balancing fixed charges, semi-fixed charges, and running costs of power plants to deliver electricity to consumers at affordable rates.
Economic sustainability – It involves designing systems, products, and processes which are financially viable, resource-efficient, and profitable over their entire life cycle without compromising social or environmental standards. It focuses on long-term value creation, minimizing total costs, and ensuring durability to avoid depleting resources.
Economic value added – It is the most widely used approach to measure the value creation. In corporate finance, economic value added is an estimate of the organization’s economic profit. It is the value created in excess of the required return of the organization’s investors. Economic value added is the profit earned by the organization less the cost of financing the organization’s capital. The idea is that value is created when the return on the organization’s economic capital employed is higher than the cost of that capital. The idea behind economic value added is rooted in economic income as opposed to accounting income. As economic income moves up or down, so goes the value of the business. The problem is that calculating economic income is not easy. It needs hundreds of adjustments. For example, under traditional accounting people expense cash disbursed for research and development (R & D), but in arriving at economic income they capitalize research and development since it provides a future economic benefit. The list of adjustments from accounting to economic is extensive such as depreciation, gains / losses, reserves, deferred taxes, etc. Since economic value added is at the centre of value-based management, it is important to keep the number of adjustments to those material items which considerably distort value.
Economizer – It is a mechanical device, typically a heat exchanger, designed to reduce energy consumption by recovering waste heat to preheat fluids (normally water) or by using cool outdoor air for HVAC (heating, ventilation, and air conditioning) system cooling. They increase overall system efficiency in boilers, and power plants.
Economy of cold heading – It refers to its extreme cost-efficiency and material savings for high-volume production, typically producing 90 parts per minute (PPM) to 300 parts per minute (PPM).
Economy of scale – It is the variation of cost with production volume. Normally, unit cost decreases with increasing volume.
Economy of scope – It is the concept that value is created more by the ability to create products with very many functions or variations from a common theme than by reducing the unit cost from increased volume of production.
Eco-profit – It is the difference between eco-benefit (EB) and eco-cost (EC), representing the net positive impact on the environment. It quantifies the advantages gained from reducing environmental burdens relative to the costs incurred in doing so.
Ecosphere – It is a planetary contained ecological system. In this global ecosystem, the different forms of energy and matter which constitute a given planet interact on a continual basis. The forces of the four fundamental interactions (gravity, electro-magnetism, weak interaction, and strong interaction, the gravitational and electromagnetic interactions produce long-range forces whose effects can be seen directly in everyday life. The strong and weak interactions produce forces at subatomic scales and govern nuclear interactions inside atoms.) cause the various forms of matter to settle into identifiable layers. These layers are referred to as component spheres with the type and extent of each component sphere varying significantly from one particular ecosphere to another. Component spheres which represent a significant portion of an ecosphere are referred to as main component spheres. For example, earth’s ecosphere consists of five primary component spheres which are the geosphere, hydrosphere, biosphere, atmosphere, and magnetosphere.
Eco-system – It is a community of inter-dependent organisms together with the environment they inhabit and with which they interact.
Eco-system approach – It is a strategy for the integrated management of land, water, and living resources which promotes conservation and sustainable use is known as ecosystem approach. An ecosystem approach is based on the application of appropriate scientific methods focused on levels of biological organization, which encompass the essential structure, processes, functions and interactions among organisms and their environment. It recognizes that humans with their cultural diversity are an integral component of several ecosystems.
Eco-system functions – It consists of the processes which are necessary for the self-maintenance of an eco-system such as primary production, nutrient cycling, decomposition, etc. The term is used primarily as a distinction from values.
Ecotoxicity – It is the potential of chemical, or physical stressors (such as pollutants, or heavy metals) to cause harmful effects on ecosystems. It measures how toxic agents disrupt natural environments, frequently focusing on immediate or delayed risks to aquatic and terrestrial life.
Ecotoxicity potential – It is a metric used mainly in ‘life cycle assessment’ (LCA) and environmental risk management to quantify the potential harm a chemical or substance can cause to ecosystems. It represents a substance’s ability to trigger adverse effects on the natural environment based on its inherent toxicity, persistence, and fate in the ecosystem.
Eddy current – It is a loop of electric current induced within conductors by a changing magnetic field in the conductor as per the Faraday’s law of induction or by the relative motion of a conductor in a magnetic field. Eddy currents flow in closed loops within conductors, in planes perpendicular to the magnetic field. They can be induced within nearby stationary conductors by a time-varying magnetic field created by an alternating current electro-magnet or transformer. The magnitude of the current in a given loop is proportional to the strength of the magnetic field, the area of the loop, and the rate of change of flux, and inversely proportional to the resistivity of the material. When graphed, these circular currents within a piece of metal look vaguely like eddies or whirlpools in a liquid.
Eddy current density – It refers to the magnitude of circulating electrical currents (eddy currents) induced within a conductive material per unit cross-sectional area, perpendicular to an alternating magnetic field.
Eddy current inspection – It is based on the principles of electro-magnetic induction and is used to identify or differentiate among a wide variety of physical, structural, and metallurgical conditions in electrically conductive ferro-magnetic and non-ferro-magnetic metals and metal parts. Eddy current inspection can be used to (i) measure or identify such conditions and properties as electrical conductivity, magnetic permeability, grain size, heat treatment condition, hardness, and physical dimensions, (ii) detect seams, laps, cracks, voids, and inclusions, (iii) sort dissimilar metals and detect differences in their composition, microstructure, and other properties, and (iv) measure the thickness of a non-conductive coating.
Eddy-current inspection technique – It is a non-destructive testing (NDT) technique used to detect surface / sub-surface flaws (cracks, corrosion) and measure physical properties (conductivity, thickness) in conductive materials. It relies on electro-magnetic induction, where alternating current in a coil creates a magnetic field which induces circular ‘eddy’ currents within a component, which, when disrupted by a defect, alter the coil’s impedance.
Eddy current loss – It is the energy wasted as heat in a conducting material, typically an iron or steel core, caused by circulating electric currents (eddy currents) induced by a changing magnetic field. These currents flow in closed loops within the conductor, dissipating power through resistive heating (P = I-square x R) and reducing the efficiency of electrical machinery like transformers, motors, and generators.
Eddy-current testing – It is an electro-magnetic non-destructive testing method in which eddy-current flow is induced in the test object. Changes in flow caused by variations in the object are reflected into a nearby coil or coils where they are detected and measured by suitable instrumentation. Eddy currents are influenced by the nature of the material such as voids, cracks, changes in grain size, as well as physical distance between coil and material. These currents form impedance on a second coil which is used to as a sensor. In practice a probe is placed on the surface of the part to be inspected, and electronic equipment monitors the eddy current in the work piece through the same probe. The sensing circuit is a part of the sending coil. The main applications of the eddy current technique are for the detection of surface or sub-surface flaws. The technique is sensitive to the material conductivity, permeability and dimensions of the product.
Eddy diffusivity – It is an improved diffusion coefficient used to model turbulent transport processes, approximating molecular diffusion but accounting for increased turbulence in fluid dynamics.
Eddy dissipation model – It is also known as the Magnussen model. It is a turbulent-chemistry interaction model used in computational fluid dynamics (CFD) to calculate reaction rates based on turbulence mixing time scales. It assumes that chemical reactions are very fast, meaning the overall combustion rate is controlled by how quickly fuel and oxidizer mix, rather than chemical kinetics.
Eddy frequency -It refers to the rate at which eddy currents are induced within a conductive material by a changing magnetic field, frequently measured in hertz or kilohertz. It is a key parameter in eddy current testing (ECT) and induction heating, where higher frequencies (up to 100 mega-hertz) allow for surface-level inspection, while lower frequencies enable deeper penetration into materials.
Eddying motion – It is also called eddy motion. It is the swirling, circular, or rotational movement of fluid elements (liquid or gas) which deviates from the main, linear flow. It is characterized by the formation of vortices or whirlpools, frequently caused when a fluid flows past an obstacle, creating turbulent, opposing currents that transfer energy and mix the fluid.
Eddy size – It refers to the spatial scale or diameter of turbulent eddies, swirling, rotating fluid structures, ranging from small turbulent motions to large geophysical features (centimeters to hundreds of kilometers). They are characterized by their length scales, which determine how they transport momentum and mix substances in liquids or gases.
Eddy structure – It is a, typically circular, rotating, or swirling pattern of fluid (liquid or gas) which deviates from the main flow, frequently formed by turbulence or, for example, water moving around an obstacle. These structures are distinct, localized, and turbulent features which move with the main flow while acting as mechanisms for transporting energy, heat, and mass.
Eddy viscosity – It is also called turbulent viscosity. It is an apparent coefficient used in fluid mechanics to model the improved mixing, transport, and energy dissipation caused by turbulent eddies, rather than molecular motion. It simplifies complex turbulent shear stresses by acting as a ‘pseudo-viscosity’ (similar to kinematic viscosity) which depends on the flow, not the fluid itself.
Eddy viscosity model – It is a turbulence model used in computational fluid dynamics (CFD) which relates Reynolds stresses to mean velocity gradients to simulate turbulent mixing. It models the effect of small-scale turbulence as an apparent turbulent viscosity added to molecular viscosity, rather than calculating eddies directly.
Edge – It is the outer boundary, margin, or border of an object or surface where it begins or ends, typically implying a sharp or narrow point. It frequently refers to the sharp side of a blade, a brink (e.g., cliff edge), a competitive advantage, or a line connecting vertices in geometry.
Edge angle – It is the angle at which a cutting tool or blade is sharpened to create its apex, typically measured between the edge bevel and the blade’s centre-line, or as the total inclusive angle. It defines the sharpness and durability of the edge such as smaller angles (15-degree to 18-degree) offer sharper, cleaner cuts, while larger angles (25-degree to 35-degree) provide increased durability.
Edge, band – It is a sharp colour demarcation in the appearance of the metal because of a difference in the work roll coating.
Edge beam – It is a longitudinal structural element, normally made of reinforced concrete, placed around the perimeter of a slab or bridge deck to provide support, stability, and protection. It supports perimeter loads, distributes forces to the foundation, and acts as a barrier against weather or impacts.
Edge, belled – It is excessive buildup of material on edge(s) during a rewinding operation. Typical causes include excessive edge burr, turned edge, and dog bone-shaped cross-sectional profiles.
Edge, broken (cracked) – It is the edge(s) containing crack, split, and / or tear caused by the inability to deform without fracturing.
Edge, build-up – It is excessive buildup of material on edge(s) during a rewinding operation. Typical causes include excessive edge burr, turned edge, and dog bone-shaped cross-sectional profiles.
Edge computing – It is a distributed, open IT (information technology) architecture which brings computation and data storage closer to the source of data, such as IoT (internet of things) devices, sensors, or local edge servers, rather than relying solely on a centralized cloud. Engineered to reduce latency, save bandwidth, and improve real-time processing, it enables immediate analysis for time-sensitive applications.
Edge conditioning – There are several applications which need reorientation or elimination of the edge burr on slit strip to facilitate handling, accommodate tooling clearances, or eliminate cracking during severe forming operations. In order to meet these needs, the slit strip is to be processed through specialized edge conditioning equipment after slitting. In cases where the intention is merely to reorient or mash down the burr to prevent personal injury or jam ups in processing equipment, the edge-conditioning unit utilizes a pair or a series of rolls which flatten the burr, or turn it 90-degree from a vertical to a horizontal plane. This method still leaves the strip with a burr, except that it sticks out instead of down, which is the direction of a slitting burr on an unconditioned edge. A modification of this method is one in which the burr is turned 90-degree to a horizontal plane and then mashed along the edge of the strip. Again, since the burr has not actually been removed, the strip cannot be thought of as deburred, although the resulting edge is satisfactory for some applications. A truly deburred edge is one which has been processed through some type of cutting tool which actually removes the burr, resulting in a cross section. There are some high-performance applications which need edges from which have been removed not only the burr, but also the brittle metal in the fracture zone of the cut, to prevent the possibility of strip breakage emanating from edge cracks. This type of edge, normally called a rounded edge, is produced by processing the strip through side-mounted shaving, filing, or grinding equipment.
Edge crack – It is a discontinuity or fracture that initiates at the free edge of a material or structural component. It typically propagates perpendicular to the tensile stress, frequently resulting from residual stresses, surface fatigue, or excessive material deformation. These cracks are common in ceramic laminates, metal sheets, and fatigue testing.
Edge cracking – It refers to the initiation and propagation of fissures at the boundary or edge of a material component. It is frequently caused by excessive tensile stress, localized deformation, or pre-existing flaws which exceed the material’s ductility, normally observed during metal rolling, forming, or in road pavement structures.
Edge, damaged – It is the edge of a coil which has been bent, torn, or scraped by an object.
Edge defect – It consists of a missing edge of a brick or block defined by three dimensional measurements.
Edge definition – It refers to the clarity and sharpness of edges in an image, which can be improved using different filters such as Laplacian and Sobel filters. These filters work by analyzing the surrounding pixel values to produce well-defined edges, hence improving image quality and perception of depth.
Edge delamination – It is a, normally undesired, mode of failure in composite laminates and layered materials where the plies separate along their interfacial boundaries, initiating at a free edge. It is driven by high interlaminar stresses—specifically shear and normal stresses—caused by differences in material properties, stacking sequences, or thermal / moisture expansion between layers.
Edge detection – It is an image processing technique which is used to identify boundaries of objects’
Edge detector – It is a tool which uses special filters to identify edges in an image based on discontinuities in color and brightness.
Edge dislocation – It is a linear crystalline defect associated with the lattice distortion produced in the vicinity of the end of an extra half-plane of atoms within a crystal. The Burgers vector is perpendicular to the dislocation line. It corresponds to the row of mismatched atoms along the edge formed by an extra, partial plane of atoms within the body of a crystal.
Edge distance – It is the distance from the edge of a bearing sample to the centre of the hole in the direction of applied force.
Edge distance ratio – It is the ratio of the edge distance to the pin diameter in a bearing test. It is also the distance from the centre of the bearing hole to the edge of the sample in the direction of the principal stress, divided by the diameter of the hole.
Edge, dropped – It is a continuous, downward edge deflection.
Edge effect – It refers to the phenomenon where physical, chemical, or manufacturing processes differ considerably at the boundary or edge of a component compared to its interior. It frequently causes, e.g., localized high-intensity scattering in imaging, or unwanted deformation in fabrication.
Edge enhancement – It is a digital image processing and computer vision technique used to increase the sharpness, contrast, and visibility of object boundaries in an image. In engineering, this process emphasizes the rapid changes in pixel intensity (edges) to help the human visual system or automated algorithms better comprehend image content.
Edge exclusion – Within the semiconductor industry, it refers to the deliberate exclusion of a defined area at the outer perimeter of a wafer (typically 2 millimeters to 3 millimeters) from active device fabrication. This area is deemed unusable because of the non-uniformity in processing steps such as ’chemical mechanical polishing’ (CMP) or coating, as well as contamination and structural defects caused by handling.
Edge extraction – It is the fundamental process of identifying and isolating sharp discontinuities in an image, representing the boundaries (edges) of objects. It works by detecting areas where image brightness or colour changes rapidly, filtering out irrelevant data while preserving essential structural information for analysis.
Edge flange joint – It is a flange weld with two members flanged at the location of welding.
Edge joint – It is a joint between the edges of two or more parallel or nearly parallel members. It is also a joint made by bonding the edge faces of two adherends.
Edge, liquated – It is the surface condition remaining after portions of a side of an as-cast rolling ingot deforms enough during hot rolling to become top and / or bottom surface(s) of the rolled product at an edge.
Edge member – It is a structural component located at the boundary or perimeter of a structure (such as a shear wall, floor slab, or bridge deck) designed to strengthen the edge, handle concentrated loads, or provide structural integrity, particularly for seismic resistance. Edge members are common in concrete structures where they reinforce areas subjected to high shear or compressive forces.
Edge pixels – These are specific pixels in a digital image representing boundaries, defined by rapid changes in intensity or colour compared to neighbouring pixels. They are identified as local extrema (maxima / minima) of image gradients (1st derivative) or zero-crossings (2nd derivative) to segment objects, improving edges for computer vision, image processing, and reconstruction.
Edge preservation – It is an image processing and signal processing technique which reduces noise while maintaining the sharpness, integrity, and structural boundaries of objects within a dataset. It ensures that critical high-frequency information, like edges, is not blurred during smoothing, important for analysis in computer vision, and seismology.
Edger – It is the portion of a die impression which distributes metal during forging into areas where it is most needed in order to facilitate filling the cavities of subsequent impressions to be used in the forging sequence.
Edge radius – It is the measured curvature applied to a sharp, machined corner to create a rounded profile, typically specified in engineering to improve part durability, safety, and functionality. It softens sharp edges, reducing stress concentrations, preventing premature failures, and easing assembly.
Edger impressions – These are also called edging impressions. These are specific, contoured cavities within a forging die used to distribute, gather, or redistribute metal during the initial stages of the forging process. Edger impressions facilitate the proper filling of subsequent cavities, ensuring that enough material is present in specific areas while reducing the quantity of waste (flash). They work the raw material (billet) to manipulate its cross-section, making it thicker in some areas and thinner in others—before it reaches the final shaping cavity.
Edge, rippled – It consists of undulation (wavy region) along the edge(s) of the metal.
Edge rolling, edge conditioning – It is the rolling a strip of steel to smooth the edges. By removing the burr off the coil so that it is safer for customers to manipulate.
Edge roughness – In engineering, specifically line edge roughness (LER) in micro-manufacturing, it is the random deviation of a fabricated feature edge from its ideal, smooth, straight-line geometry. It characterizes the high-frequency variations in a sidewall profile, measured through scanning electron microscopy (SEM) or atomic force microscopy (AFM), and is important for determining semiconductor device performance, such as transistor gate behaviour.
Edge separation – It typically refers to the fracturing, tearing, or splitting of the edges of metal products during mechanical processing, such as rolling, forging, or drawing. This defect is normally caused by the exhaustion of the material’s ductility at the edge, where stresses are highest, leading to premature failure before the bulk of the material reaches its limit.
Edge stability – It is an indicator of strength in a green compact which can be determined by tumbling in a drum.
Edge strain – It consists of transverse strain lines or Luders lines ranging from 25 millimeters to 300 millimeters from the edges of cold rolled steel sheet or strip. Luder lines are elongated surface markings or depressions in sheet metal, frequently visible with the unaided eye, caused by discontinuous (inhomogeneous) yielding.
Edge strength – It is the resistance of the sharp edges of a compact against abrasion. It can be determined by tumbling in a drum.
Edge-trailing technique – It is a unidirectional motion perpendicular to and toward one edge of the sample during abrasion or polishing. It is used to improve edge retention.
Edge vortex – It is a vortex formed when flow separates at the leading or trailing edge of an airfoil, resulting in a shear layer which rolls up to create the vortex. Leading edge vortices (LEVs) improve lift by inducing a low pressure region on the upper surface of the wing, while trailing edge vortices (TEVs) are generated from the shear layer shed at the trailing edge.
Edge, wavy – It is the undulation (wavy region) along the edge(s) of the metal.
Edge weld – It is a weld in an edge joint.
Edge weld size – It is the weld metal thickness measured at the weld root.
Edgewise mode – It refers to the in-plane vibrational pattern of a wind turbine blade, where the motion occurs parallel to the chord line (leading-to-trailing edge) rather than bending out-of-plane. It is a lowly damped, in-plane deformation, typically the second natural frequency mode after the out-of-plane flap wise mode.
Edging – In sheet metal forming, it consists of reducing the flange radius by retracting the forming punch a small amount after the stroke but before release of the pressure. In rolling, it is the working of metal in which the axis of the roll is parallel to the thickness dimension. It is also called edge rolling. It is also the forging operation of working a bar between contoured dies while turning it 90-degree between blows to produce a varying rectangular cross section. In a forging, it is the removing flash which is directed upward between dies, normally accomplished by using a lathe.
Edging impression – It is the portion of a die impression which distributes metal during forging into areas where it is most needed in order to facilitate filling the cavities of subsequent impressions to be used in the forging sequence.
Edging mill – It is equipped with caliber rolls and has the function of adjusting the flange widths of products. In the universal mill, variations of flange-thickness and web- thickness can be made easily by adjusting the roll gap in the edging mill. The edging mill is normally a two-high, single groove mill stand.
Edison effect – It is also known as thermionic emission. It is the phenomenon where electrons are emitted from a hot surface, like a heated metal, and can flow through a vacuum or gas. It is a key principle behind vacuum tubes and other electronic devices.
Educational programmes – These are the structured initiatives designed to facilitate learning and knowledge dissemination, frequently including different formats such as teleconferences and speaker engagements.
Effect – It means that the first event ‘A’ (the cause) is a reason which brings about the second event ‘B’ (the effect).
Effect absorption chiller – It is a thermodynamic system which uses heat to produce cooling effects through absorption refrigeration, operating in single, double, or triple-effect configurations, with each effect representing an additional stage of heat exchange and cooling efficiency.
Effect chiller – It typically refers to an absorption refrigeration system which generates cooling by utilizing heat rather than electricity. The ‘effect’ denotes the number of distinct thermodynamic stages (single, double, or triple) used to boil the refrigerant out of an absorbent solution, with higher-effect stages yielding greater efficiency. Absorption chillers are normally classified into three types based on the number of thermodynamic cycles and generators they contain (i) single-effect chiller, (ii) double-effect chiller, and (iii) triple-effect chiller.
Effect diagram – It is normally known as a cause-and-effect diagram or Ishikawa / fishbone diagram. It is a visual tool used to identify, organize, and analyze all the potential factors which contribute to a specific problem, event, or ‘effect’.
Effective angle – It normally refers to the actual, operational angle of a tool, die, or material feature during a process, rather than its static or nominal design angle. It is also the angle which, along with the detection range, forms the sector-shaped field of view of a sensor, determining the area within which a target point can be detected.
Effective angle – It is the angle α that, along with the detection range, forms the sector-shaped field of view of a sensor, determining the area within which a target point can be detected.
Effective angle of attack – It is also called impact angle. It is the angle between the trajectory of an impinging particle and the surface of the target material. It represents the actual angle at which particles strike a surface, which is important for determining whether the material experiences cutting, plowing, or deformation wear.
Effective area – In an actuator, it is the part of the diaphragm or piston area which produces a stem force. The effective area of a diaphragm can change as it is stroked. It is normally a maximum at the start and a minimum at the end of the travel range. Moulded diaphragms have less change in effective area than flat sheet diaphragms. Hence, molded diaphragms are desired.
Effective axial force – It is a design concept which accounts for the combined effect of true internal / external pressures, temperature variations, and structural stress on a component, mainly used for global stability analysis. It defines the total force influencing phenomena like buckling, rather than just the physical material stress.
Effective bandwidth – It is a measure of the actual, usable data transfer rate, representing a realistic upper limit to capacity rather than the theoretical maximum. It acts as the minimum service rate or transmission speed needed to support a specific data flow while maintaining quality of service (QoS) constraints, such as specific queue lengths or latency requirements.
Effective case depth – It is the perpendicular distance from a hardened part’s surface to the point where a specified hardness level is maintained. It represents the functional, load-bearing layer, normally defined as the depth where hardness equals 50 HRC (hardness Rockwell C-scale). This measure ensures a hard, wear-resistant exterior while maintaining a tough, ductile core.
Effective channel – It is a, marketing, or operational pathway which successfully achieves its intended purpose, such as driving sales, engaging customers, or distributing information, with maximum efficiency, high return on investment (ROI), and minimal wasted effort or cost. It optimizes both performance and cost-effectiveness for both the organization and the user.
Effective coefficient of thermal expansion – It is a measure which combines the thermal expansion coefficients of a base fluid and nano-particles in a nano-fluid, influenced by their respective volume fractions and densities. It can be calculated using theoretical models that account for the contributions of both constituents to the overall thermal expansion behaviour.
Effective communication – It is the process of exchanging information, ideas, thoughts, and emotions, where the message is received and understood by the recipient exactly as the sender intended. It goes beyond just sharing information, focusing on clarity, purpose, and mutual understanding, often requiring active listening and nonverbal cues. Key elements and characteristics of effective communication include (i) the 5 C’s namely clear, correct, complete, concise, and compassionate, (ii) mutual understanding, (iii) two-way process, (iv) contextual adaptation, and (v) goal-oriented.
Effective compression ratio – It is the actual volume ratio used to calculate compression and expansion within an engine’s cylinder. Unlike the static (or nominal) compression ratio, which measures the total geometric volume of the cylinder, the effective ratio only accounts for the compression phase after the intake valves fully close. The effective compression ratio concept mainly depends on whether you are talking about engine mechanics or data storage / processing.
Effective configuration – It refers to the optimal, error-free setup of a system, software, or process which meets its performance, security, and functional requirements. It is achieved through configuration management, which involves documenting settings, enforcing policies, and controlling changes to maintain stability and reliability.
Effective confining pressure – It is the actual confining pressure acting on a material reduced by the internal pore fluid pressure. It determines a material’s true strength, deformation behaviour, and permeability under load. The concept is important in geo-mechanics, soil mechanics, and structural geology.
Effective crack length – It is a theoretical crack length used in fracture mechanics. It represents the true physical crack length plus an adjustment which accounts for the deformation and stresses at the crack tip. It allows engineers to calculate crack growth and material durability more accurately without getting bogged down by the complex, microscopic behaviour of the material right at the crack’s edge.
Effective crack size – It is the physical crack size augmented for the effects of crack tip plastic deformation. Sometimes the effective crack size is calculated from a measured value of a physical crack size plus a calculated value of a plastic zone adjustment. A preferred method for calculation of effective crack size compares compliance from the secant of a load-deflection trace with the elastic compliance from a calibration for the type of sample.
Effective curvature – It typically refers to the practical, modified, or simplified measure of how sharply a curve, surface, or structural element bends. It adjusts the pure geometric definition to account for real-world factors like material degradation, structural deformation, or fluid dynamic effects, rather than just raw math.
Effective date – It is the specific day on which a legal agreement, policy, or statute officially becomes operative and enforceable. It marks the exact moment when parties are required to begin fulfilling their obligations and exercising their rights, regardless of when the document has been actually signed.
Effective diffusion coefficient – It is a macroscopic parameter which quantifies the overall rate of atomic transport, averaging multiple simultaneous diffusion mechanisms (such as lattice, grain boundary, and dislocation diffusion) into a single value. It is used to model complex, real-world polycrystalline materials rather than ideal single crystals.
Effective diffusivity – It is an overall mass transport property of water in drying materials, encompassing mechanisms such as liquid diffusion, vapour diffusion, and hydrodynamic flow, and is typically modelled using Fick’s second law under the assumption of negligible shrinkage.
Effective dose – It is a dose quantity in the International Commission on Radiological Protection system of radiological protection. It is the tissue-weighted sum of the equivalent doses in all specified tissues and organs of the human body.
Effective draw – It is the maximum limits of forming depth which can be achieved with a multiple-action press. It is sometimes called maximum draw or maximum depth of draw.
Effective earth radius – It is a technical concept in radio frequency (RF) and micro-wave engineering related to propagation and channels. It refers to a specific parameter, component, or methodology used in the design, analysis, or measurement of radio frequency systems. Understanding Effective earth radius is necessary for engineers working in telecommunications, and wireless systems.
Effective elastic constant – It is a macroscopic parameter used to describe the overall stiffness of a structurally heterogeneous material (like a composite or a porous structure) by treating it as a single, uniform solid. It translates microscopic, localized complexities into simplified mathematical models.
Effective extrusion rate – It is frequently referred to as the effective extrusion ratio. It represents the ratio of the initial cross-sectional area of the billet to the final cross-sectional area of the extruded profile. It is the core, dimensionless parameter quantifying the magnitude of plastic deformation and compressive forces applied to a material, typically calculated as ‘R = Ao /Af’, where ‘R’ is extrusion ratio, ‘Ao’ is the cross-sectional area of the initial billet, and ‘Af’ is the final cross-sectional area of the extruded product.
Effective field – It is a simplified physical or mathematical model which describes phenomena at a specific length or energy scale, while intentionally ignoring complex, smaller-scale or higher-energy details. It is an approximation tool allowing for precise calculations without solving for every microscopic interaction.
Effective flange width – It is a design concept used in reinforced concrete and composite steel-concrete structures to simplify the analysis of T-beams or L-beams. It represents a reduced portion of a slab, rather than its full width, which acts compositely with the web to resist bending and compression, effectively accounting for non-uniform stress distribution (shear lag) across the flange.
Effective heat capacity method – It is a numerical modelling technique used to simulate transient heat transfer involving phase changes, such as melting or solidification. It accounts for latent heat by artificially boosting a material’s physical heat capacity across a specific phase-change temperature range.
Effective height – It is a specialized metric which normally describes the theoretical or active height which governs a system’s behaviour, rather than its physical dimension. In column and wall design, it is the unsupported length of a vertical member used to calculate its buckling or slenderness capacity. It varies based on end restraints (e.g., fixed or pinned). It also defines the distance from the foundation to the centroid of lateral inertial forces during earthquakes. It determines the overturning moment and displacement limits. In case of telecommunications, It is frequently used interchangeably with effective length. It represents the hypothetical length of a straight wire which produces the same far-field radiation as the actual antenna. Mathematically, it is the ratio of the open-circuit terminal voltage (Voc) induced in a receiving antenna to the incident electric field strength (E) (He = Voc/E). In case of atmospheric dispersion, it is also known as the effective release height. It is the sum of the physical stack height and the additional rise of the exhaust plume because of the buoyancy and momentum. In dams, effective height refers to the difference in elevation between the spillway crest (or top of the dam) and the lowest point of the downstream toe.
Effective hydrogen index – It is an indicator defining the net hydrogen-to-carbon ratio of a feedstock (especially biomass or pyrolysis liquids). It accounts for hetero-atoms, estimating the hydrogen available after subtracting the quantity needed to completely remove oxygen, nitrogen, and sulfur as water, ammonia, and hydrogen sulphide.
Effective incidence – It defines the actual operating angle between an incoming fluid or light ray and a component’s reference line, accounting for interference. Since surrounding conditions (like downwash in aerodynamics or diffuse light in optics) distort straight-line measurements, effective incidence measures the true, resulting physical interaction.
Effective inertia – It is a modified or referred property used to simplify complex, multi-component systems. It represents the single, equivalent value of a system’s resistance to acceleration, allowing engineers to evaluate dynamic behaviour without calculating every moving part individually.
Effective isotropic radiated power – It is the total power, in watts or dBm (decibel-milliwatts) , which a theoretical isotropic antenna (one radiating equally in all directions) needs to emit to produce the same maximum power density as an actual antenna in its peak radiation direction. It accounts for transmitter power, cable losses, and antenna gain, serving as a key regulatory metric.
Effective leakage area – It is the orifice flow area which results in the same calculated flow for a given pressure drop as is measured for the seal in question. This concept is useful when comparing the leakage performance of seals of different sizes and designs, and of seals operating under different conditions.
Effective length factor – It is a coefficient used to calculate a column’s buckling capacity. It represents the ratio of a column’s actual length to its effective length, the length between points of zero moment, transforming an end-restrained column into an equivalent pin-ended (Euler) column. The factor is necessary for calculating the slenderness ratio, which determines how susceptible a member is to buckling under compressive loads.
Effective lifetime – It is the anticipated duration a component, material, or system maintains acceptable performance before needing replacement or failing. It is a proactive metric calculated by factoring in manufacturer specifications, operational environments, and maintenance strategies.
Effective mass – It refers to how a particle or structure appears to resist acceleration when subjected to external forces. In solid-state electronics, the effective mass is the apparent mass of an electron or hole moving through a crystalline lattice. Since charge carriers interact with the periodic potential of the atoms, they do not behave like free particles in a vacuum. In structural dynamics, modal effective mass is the portion of a structure’s total mass which actively participates in a specific mode of vibration.
Effective mass approximation – It is a quantum mechanical simplification in solid-state physics and engineering. It allows charge carriers (electrons and holes) in a crystalline material to be treated as free particles, but with an artificially adjusted mass. This accounts for how the material’s periodic atomic potential alters their movement.
Effectiveness – It is the degree to which a system, component, or process achieves its planned goals, requirements, and desired outputs. It focuses on ‘doing the right things’, ensuring the final result meets user needs and performance specifications, frequently measured by quality, reliability, and success rate, rather than just minimizing resource usage (efficiency).
Effective notch stress – It is the total linear-elastic stress calculated at a notch, such as a weld toe or root, by applying a fictitious rounding (typically r = 1 millimeter for steel of above 5 millimeter, or r = 0.05 millimeter for thin sheets of below 5 millimeter). This method simplifies complex weld geometries estimated fatigue life based on local stresses rather than nominal stress. It is a standard method used to evaluate and predict the fatigue life of complex welded structures and components.
Effective nuclear charge – It is an electron in a multi-electron atom or ion. It is the number of elementary charges. The term ‘effective’ is used since the shielding effect of negatively charged electrons prevent higher energy electrons from experiencing the full nuclear charge of the nucleus because of the repelling effect of inner layer. The effective nuclear charge experienced by an electron is also called the core charge. It is possible to determine the strength of the nuclear charge by the oxidation number of the atom. Most of the physical and chemical properties of the elements can be explained on the basis of electronic configuration. It considers the behaviour of ionization energies in the periodic table. It is known that the magnitude of ionization potential depends upon the several factors namely (i) the size of an atom, (ii) the nuclear charge and oxidation number, (iii) the screening effect of the inner shells, and (iv) the extent to which the outermost electron penetrates into the charge cloud set up by the inner lying electron In the periodic table, effective nuclear charge decreases down a group and increases left to right across a period.
Effective over-burden pressure – It is also called effective vertical stress. It is the downward pressure exerted by the weight of overlying soil and rock, minus the pressure of the water trapped in the pore spaces. It is the true inter-granular stress driving soil settlement, shear strength, and foundation capacity.
Effective period – It refers to the specific timeframe, duration, or cycle during which a system, component, design, or material operates within its designated parameters, holds validity, or maintains structural integrity. It is frequently used to calculate performance, reliability, or scheduling in engineering, manufacturing, and structural design.
Effective permeability -It is the specific ability of a porous material to transmit a single fluid when multiple fluids are present. It is highly dependent on the saturation levels of each fluid, and contrasts with absolute permeability, which measures the flow rate when only one fluid occupies the pore space.
Effective plastic strain – It is a single, monotonically increasing scalar value which represents the total accumulated, irreversible deformation in a material. It condenses complex, multi-axial strain components into a single metric, making it necessary for predicting structural yielding, crack propagation, and material failure in engineering simulations.
Effective polarizability – It is the macroscopic or ‘averaged’ response of a material’s atoms, molecules, or structures to an external electric field. It accounts for complex, real-world conditions like boundary constraints, local field interactions, and particle geometries, rather than isolated vacuum values.
Effective pressure – It normally refers to ‘mean effective pressure’ (MEP). It is a theoretical average pressure acting on a piston inside an internal combustion engine during one complete cycle. It is a vital metric used to evaluate engine capacity and compare power output independently of the engine’s size.
Effective radiation dose – it is the quantity got by multiplying the equivalent radiation dose to different tissues and organs by a weighting factor appropriate to each and summing the products. Its unit is Sievert, symbol Sv. It is frequently abbreviated to dose.
Effective radius – It is a theoretical value used to simplify complex, irregular, or non-ideal systems into an equivalent, idealized circular model. Its exact definition and mathematical calculation change depending on the specific engineering discipline.
Effective reflectivity – It is the net or combined ratio of reflected radiation (light or heat) to incident radiation for a composite surface, system, or cavity, rather than a single material interface. It accounts for multiple reflections, structural properties, and geometric arrangements.
Effective refractive index – It is a number quantifying the phase delay per unit length in a waveguide, relative to the phase delay in vacuum. The effective refractive index of optical waveguides is found to be describable by an integral expression as a square-root of field-distribution-weighted-mean of squared refractive index distribution.
Effective resistance – It is also called total or equivalent resistance. It is the single, combined value which represents the total opposition a circuit or component offers to the flow of electric current. It acts like a ‘stand-in’ resistor which replaces multiple interconnected components, drawing the exact same quantity of total current from the voltage source.
Effective rolling radius – It is the ratio of a vehicle’s forward linear velocity to its wheel’s angular velocity. It represents the theoretical distance from the wheel’s centre to the ground that determines actual vehicle speed, powertrain rpm (revolutions per minute), and torque, effectively acting as the bridge between a tyre’s un-loaded and loaded states.
Effective series resistance – It is also called equivalent series resistance. It is the total parasitic resistive loss in an electronic component. It represents all the internal non-ideal resistances, such as metallic leads, electrodes, and dielectric losses, acting in series with an ideal component like an ideal capacitor. For a non-ideal component like a capacitor, battery, or solar cell, effective series resistance (ESR) quantifies the internal energy lost as heat when current flows through it. In basic circuit theory, effective series resistance refers to the single, total resistance which replaces multiple physical resistors wired in a single path (series).
Effective spring constant – It represents the overall stiffness of a complex mechanical system comprised of multiple interconnected springs or flexible components. It simplifies the entire assembly into a single, hypothetical spring which deflects identically to the combined system under the same applied force.
Effective strain – It is frequently called effective plastic strain or von Mises strain. It is a scalar quantity which reduces complex, multi-axial strain states (tensors) into a single, monotonically increasing value. It represents the cumulative magnitude of plastic deformation, and is important for modelling metal plasticity.
Effective strain rate – It is a single scalar value used to represent the overall intensity of a complex, multi-axial state of deformation. It condenses the different directional and shear strain rates into a single metric, normally used in metal forming and plasticity theories.
Effective stress – It is a calculated parameter which is used in a mathematical expression that predicts the onset of an event (typically yield and fatigue failure) when a critical value of the effective stress is obtained. The most common effective stress is the von Mises stress.
Effective stress concept – It is the nominal stress adjusted for the presence of damage in a material, represented by the equation ‘S* = S/(1 – D)’, where ‘D’ is the damage variable quantifying the irreversible defects affecting the material’s resistance.
Effective stress intensity factor (Keff) – It describes the actual stress state driving crack propagation at a crack tip. It is mainly used in fatigue analysis to account for the crack closure phenomenon, where the crack faces remain pressed together even under tensile loading.
Effective stress intensity range (dKeff) – It is the portion of the applied cyclic stress intensity factor range (d = Kmax – Kmin) which actually contributes to fatigue crack growth, accounting for crack closure mechanisms. It is defined as ‘dKeff = Kmax – Kop’, where ‘Kop’ is the stress intensity at which the crack opens, excluding the part of the cycle where the crack is closed.
Effective stress tensor – It represents the physical stress which governs the mechanical behaviour, such as deformation, strength, and fatigue, of a porous or damaged material. It isolates the forces actively causing structural change from external fluid pressures or internal defects.
Effective structure – It is a well-planned, deliberate framework which dictates how roles, responsibilities, and information are organized. It aligns the organizational strategy with execution, eliminates operational bottlenecks, and maps out clear communication channels to maximize productivity and achieve organizational goals. In structural engineering, effective structure is the systematic translation of architectural concepts into safe, functional, and durable load-bearing systems. It defines load paths, material properties, and geometric constraints to ensure the structure withstands all anticipated forces without excessive deformation or failure. A well-defined structural system balances stability, strength, and serviceability.
Effective temperature – It is an experimentally determined index which combines dry-bulb temperature, humidity, radiant conditions, and air movement to indicate the thermal sensation experienced in a given space. It represents the dry-bulb temperature of a thermo-equivalent environment at 50 % relative humidity and specific radiation conditions, serving as a reliable indicator of thermal comfort or discomfort.
Effective tension – It is the net axial force within a structural element (like a pipe, cable, or drill string) which accounts for both the physical wall tension and the surrounding internal and external fluid pressures.
Effective thermal conductivity – It is a property representing the overall heat transfer capacity of a heterogeneous, composite, or porous material. It simplifies complex microscopic mechanisms (like conduction through solids, fluids, and voids) into a single, mathematically equivalent value.
Effective throat – It is the minimum distance minus any convexity between the weld root and the face of a fillet weld.
Effective voltage – It is the equivalent steady direct current (DC) voltage which delivers the exact same heating or power to a purely resistive load as the alternating current (AC) signal. It is very frequently referred to as ‘root mean square’ (RMS) voltage.
Effective volume fraction – It is the ratio of the functionally active or load-bearing volume of a specific constituent to the total volume of the composite or mixture. It adjusts the raw (geometric) volume fraction to account for particle interactions, voids, or material damage. The concept is vital for understanding physical and mechanical properties like stiffness, thermal conductivity, and fluid flow. It is heavily utilized in three main contexts namely composite materials, fluid mechanics and colloids, and structural mechanics and damage.
Effective wellbore radius – It is an equivalent radius used in hydrogeological engineering to simplify complex near-wellbore flow conditions into an ideal, radial-flow mathematical model. It mathematically substitutes real-world formation damage or stimulation with a theoretical, altered wellbore size.
Effective yield strength – It is an assumed value of uniaxial yield strength which represents the influence of plastic yielding on fracture test parameters.
Effect of porosity diagram – It visually demonstrates how the volume of void spaces in a material relates to its physical, mechanical, and transport properties. It maps how changes in pore volume alter the material’s strength, fluid flow, and thermal behaviour.
Effect size – It is a measure of the strength of a relationship between two variables. Effect size statistics are used to assess comparisons between correlations, percentages, mean differences, probabilities, and so on.
Effect transistors – These refer to a class of transistors, such as the gated quantum well transistor, which utilize mechanisms like resonant tunneling and the Stark effect to achieve properties such as negative trans-conductance and negative differential resistance (NDR), hence enabling modulation of tunneling current through gate field influence on energy levels.
Effervescence – It is the escape of gas from an aqueous solution without the application of heat, and the bubbling, foaming, or fizzing which results. For example, the release of carbon di-oxide from carbonated water.
Efficacy – It is the ability to perform a task to a satisfactory or expected degree. It is the quantity of energy service or useful energy delivered per unit of energy input. It is frequently used in reference to lighting systems, where the visible light output of a luminary is relative to power input, expressed in lumens per Watt. The higher the efficacy value, the higher is the energy efficiency.
Efficiency – It refers to the effectiveness with which a particular quantity of inputs is deployed to generate an output. When a process is technologically efficient, it produces a specific quantity of output using the least quantity of inputs.
Efficiency coefficient – It is a dimensionless ratio which measures how well a system, machine, or process converts input energy or work into useful output. It evaluates performance by quantifying losses to friction, heat, or resistance.
Efficiency droop – It is the phenomenon where a light-emitting diode (LED) becomes less efficient at converting electrical energy into light as its operating current increases. While light-emitting diodes are most efficient at low currents, engineers push higher currents through them to achieve bright illumination, causing a severe drop in efficiency.
Efficiency factor – It is a metric which indicates how well a system or process is utilizing resources to achieve desired outcomes. It is essentially a ratio or percentage that compares output to input, highlighting the effectiveness of a process. The specific application and interpretation of ‘efficiency factor’ can vary depending on the context.
Efficiency indicator – It is a quantifiable metric used to measure how effectively a system, process, or machine converts inputs (like energy, time, or materials) into useful outputs. It evaluates technical performance, operational productivity, and optimization.
Efficiency level – It measures how well a system or process converts inputs (like time, energy, and money) into useful outputs, while minimizing waste. In mechanics and electronics, the efficiency level is the percentage of energy which is successfully transferred into useful work. In commercial operations, efficiency levels rate how effectively resources (labour, capital, materials) are utilized to maximize production or generate revenue. In data science and mathematics, an efficiency level compares the quality of different statistical estimators. An efficient estimator is one which needs the smallest sample size to accurately estimate a parameter, minimizing variance and error.
Efficiency of process – It is the ratio of useful output to the resources (time, effort, and capital) put in. It measures how smoothly a process runs by evaluating whether operations are converting inputs into valuable outputs with minimal waste, cost, or delay. Understanding and refining the efficiency of the processes involves measuring specific metrics, identifying bottlenecks, and balancing output.
Efficiency-related quality – It refers to a system’s ability to deliver a needed level of performance using minimal resources (e.g., time, energy, materials, or computational power). It is the engineering metric for ‘doing things right’ without waste, directly impacting cost-effectiveness and operational sustainability.
Efficiency, statistical – A statistical estimator or estimate is said to be efficient if it has small variance. In majority of the cases a statistical estimate is preferred if it is more efficient than alternative estimates. It can be shown that the Cramer-Rao bound represents the best possible efficiency (lowest variance) for an unbiased estimator. That is, if an unbiased estimator is shown to be equivalent to the Cramer-Rao bound, then there are no other unbiased estimators which are more efficient. It is possible in some cases to find a more efficient estimate of a population parameter which is biased.
Efficient construction materials – These are specially engineered products and systems designed to minimize energy use, reduce environmental impact, and lower lifecycle costs while maintaining structural integrity. In engineering, these materials optimize the balance between a building’s mechanical performance, its thermal properties, and its long-term ecological footprint.
Efficient cryptographic algorithm – It is the disciplined process of designing, implementing, and optimizing mathematical procedures which protect data, ensuring confidentiality, integrity, authenticity, and non-repudiation, while minimizing consumption of computational resources like time, memory, and battery power. It balances strict security requirements against the practical constraints of modern computing environments, such as internet-of-things (IoT) devices, high-throughput network protocols, and mobile systems.
Efficient estimator – It is an unbiased estimator which possesses the lowest possible variance (or mean squared error) among all alternative estimators. It extracts the maximum quantity of usable information from the available data, ensuring optimal precision and the narrowest possible margin of error.
Efficient investment – It refers to the allocation of resources in a manner which maximizes benefits while minimizing costs, particularly in the context of solar energy and energy conservation systems. It involves analyzing capital, energy, and operational expenditures to reduce total lifetime costs effectively.
Efficient maintenance – It is maximizing equipment reliability and performance while minimizing the resources consumed, such as time, labour, and spare parts. It ensures tasks are completed promptly and accurately, directly reducing costly downtime and eliminating waste. An efficient maintenance strategy balances several core principles such as flawless execution, resource availability, and optimized timing.
Efficient model – It is a system, algorithm, or framework designed to maximize output, accuracy, or desired results while minimizing the consumption of resources (e.g., time, memory, energy, or data). It balances performance with computational constraints to achieve the best possible outcomes without waste.
Efficient process – It is the strategic design, implementation, and optimization of workflows to maximize output while minimizing resource waste (time, cost, materials). It involves calculating process efficiency as the ratio of value-added time to total lead time or output to input, frequently using lean, six sigma, and automation to achieve peak performance, safety, and regulatory compliance.
Efficient product – It streamlines the transformation of concepts into market-ready solutions by aligning technical requirements with organizational goals and user needs early. It optimizes cost, accelerates time-to-market, and ensures quality through agile development, cross-functional collaboration, and validation of design specifications.
Efficient representation – It is a data encoding or modeling strategy which minimizes redundancy, reduces computational overhead, and optimizes memory usage while preserving the critical features needed for accurate processing. It ensures maximum information is retained with minimal structural complexity.
Efficient work – It is defined as the ratio of useful energy output / power output to the total energy input / power input. It measures how well a system converts input into desired output, minimizing losses because of the friction, heat, or waste, normally expressed as a percentage.
Efficient working – It is the ability to achieve maximum desired results or output while minimizing the waste of resources, such as time, effort, money, or materials. It involves working in a highly organized, competent, and frequently rapid manner to maximize productivity without sacrificing quality.
Efficient workplace – It is an environment designed to maximize output (productivity, quality, and results) while minimizing input, specifically wasted time, effort, and resources. It blends streamlined processes, smart technology, and optimized employee performance to achieve goals quickly and sustainably.
Effluent – It is the liquid waste from industry. It is the wastewater from sewers or industrial outlets which flows directly into surface waters, either untreated or after being treated at a facility. The term refers frequently to a treated liquid released from a wastewater or effluent treatment process.
Effluent concentration – It refers to the specific quantity or mass of a pollutant contained within a defined volume of liquid or gas exiting a treatment system, industrial process, or chemical reactor. It represents the final ‘output’ quality before discharge or reuse.
Effluent limitation – It is a legal and engineering restriction on the quantities, rates, and concentrations of pollutants discharged from a facility into receiving waterways. It sets the maximum allowable limits for physical, chemical, and biological constituents to ensure environmental compliance and protect water quality. These limits form the foundation for designing wastewater treatment systems.
Effluent pH – It defines the measure of acidity or alkalinity of the liquid waste discharged from a treatment plant, sewer, or industrial outfall into the environment. It is mathematically expressed as the negative base-10 logarithm of the hydrogen ion activity in moles per litre.
Effluent plume – It is also known as mixing zone. When effluent is discharged into a river, it frequently has a different water chemistry than the river. This discharge maintains its integrity for some distance down-stream before it mixes completely with the river water. This relatively un-mixed effluent is detectable by sampling across the river and is called a plume.
Effluent standards -These are regulations specifying the maximum allowable concentrations of pollutants in treated wastewater (effluent) before it is discharged into the environment, aiming to protect water quality and human health. Effluent standards specify concentrations of pollutants expressed in terms of parts per million for waste-water discharged.
Effluent stream – It is a liquid, gas, or slurry flowing out of a process, facility, or treatment system. It mainly refers to wastewater or chemical byproducts discharged from industrial plants, or sewage systems which need monitoring, treatment, or environmental compliance before being released or reused.
Effluent treatment plant – It is a facility which treats the wastewater or effluent generated by industrial activities before they are discharged into the environment. The main purpose of an effluent treatment plant is to remove pollutants from industrial wastewater to meet environmental statutory norms requirement for water quality and prevent contamination of water bodies. This treatment helps in protecting ecosystems and human health from industrial pollutants.
Effluent treatment system – It is a facility designed to manage and purify industrial wastewater. Its main goal is to safely treat contaminated water so it meets environmental discharge standards or can be recycled back into industrial processes. It involves a multi-stage approach, combining physical, chemical, and biological processes to remove a wide variety of pollutants like oils, grease, heavy metals, and toxic chemicals.
Effort – The quantity of man-power needed to complete a task. It is measured in man-hours or similar units.
Effort delivery – It refers to predicting the workforce and time needed to build a system (effort estimation). It also refers to a networking service model where packets are sent without establishing a prior connection, with the network making its best effort to deliver them to the intended destination, despite potential issues such as loss, corruption, or mis-delivery. This model is characterized as unreliable, meaning that there are no mechanisms in place for recovery from delivery failures.
E-fibre – It is vert frequently referred to as E-glass fibre. It is the standard, general-purpose glass fibre used for electrical insulation, high mechanical strength, and structural reinforcement in composite materials. The ‘E’ stands for ‘electrical’, as it has been originally developed for stand-off electrical wiring insulation.
E-fuels – These are also called electro-fuels. These are synthetic hydro-carbons produced by combining hydrogen generated through water electrolysis with captured carbon di-oxide. Powered by renewable energy, they offer a closed-loop, near-zero emissions alternative to fossil fuels while retaining the exact same chemical properties as conventional gasoline, diesel, or jet fuel.
E-glass – It is a family of glasses with a calcium alumino-boro-silicate composition and a maximum alkali content of 2 %. It contains a general-purpose fibre which is most frequently used in reinforced plastics, and is suitable for electrical laminates because of its high resistivity. It is also called electric glass.
E-glass fibre – It is also called electrical glass fibre. It is the industry standard, general-purpose glass fibre mainly used to reinforce polymer composites. It is an alkali-free alumino-borosilicate glass prized for its excellent electrical insulation, high tensile strength, and low cost, accounting for roughly 90 % of global fibre-glass production. It is the fundamental reinforcement material used across several industries.
Eigenanalysis – it is also called eigenanalysis method. It is a technique used to simplify complex linear transformations. It breaks down a square matrix into fundamental building blocks, eigenvalues and eigenvectors, which reveal the hidden structure, behaviours, and most important dimensions of a dataset or physical system. The method relies on the core equation ‘A x v = lambda x v‘, where ‘A’ is a square matrix (representing a transformation), ‘v’ is an eigenvector, a non-zero vector which changes only in scale (stretched or compressed), but not in direction, when transformed by ‘A’, and ‘lambda’ is an eigenvalue, a scalar value representing the exact factor by which the corresponding eigenvector is scaled.
Eigendecomposition – It is a method which factors a square matrix (A) into its fundamental components: eigenvectors (P) and eigenvalues (lambda). It breaks down a linear transformation into simpler, diagonal components, revealing how the matrix stretches or compresses data along specific directions.
Eigenfrequencies – These are defined as the number of cycles of a freely vibrating system per unit time, with their inverse being the natural period of vibration. They are related to the natural circular frequency in harmonic motion, indicating the system’s response characteristics.
Eigenfunction – It is a special function which, when subjected to a linear operator (such as a derivative), yields a scalar multiple of itself. This scalar multiplier is called the eigenvalue.
Eigenfunction expansion – It is a technique used to represent complex, arbitrary functions as an infinite series of simpler, orthogonal basis functions (eigenfunctions). It is widely used to solve partial differential equations (PDEs) in structural mechanics, heat transfer, and fluid dynamics. Engineers use this method to break down complicated physical states (such as the temperature distribution across a cooling plate or the vibrations of a bridge) into a sum of distinct, independent fundamental modes.
Eigenket – It is also caked eigenvector. It is a special state vector which, when subjected to a linear transformation (matrix operator), retains its original direction and is only scaled by a scalar multiplier called an eigenvalue. It defines the fundamental, uncoupled modes or characteristic behaviours of a system.
Eigenmode – It is also called natural mode. It is a specific, fundamental pattern of vibration or wave propagation in which a physical system naturally oscillates. Every system, from a steel bridge to a microchip’s optical waveguide, has a distinct set of discrete frequencies and corresponding deformation shapes at which it prefers to vibrate.
Eigenpair – It is a matching set of an eigenvector (a direction which remains unchanged during a linear transformation) and its corresponding eigenvalue (the scalar factor by which that vector is scaled). Eigenpairs are represented by the equation ‘A x v = lambda x v’ where ‘A’ is the system, ‘v’ is the eigenvector, and ‘lambda’ the eigenvalue. Eigenpairs are necessary for breaking down complex physical systems into simpler, independent behaviours. They allow engineers to analyze structural stability, predict failures, and optimize designs across different disciplines.
Eigensolution – It refers to the process and outcome of finding the eigenvalues (scalars) and eigenvectors (vectors) of a system’s governing equations. It is used to analyze dynamic behaviours, such as determining a structure’s natural frequencies and mode shapes, ensuring structural integrity and stability.
Eigenstate – It is a specific state of a physical system which yields a determinate, predictable value (its eigenvalue) when a specific observable property is measured. It provides the foundational mathematical and physical certainty for quantum mechanics.
Eigenstrain – It is a permanent or inelastic deformation in a material which is not caused by an external mechanical stress. It acts as the internal source for residual stresses and includes dimensional changes from sources like thermal expansion, phase transformations, plasticity, or curing.
Eigenstructure assignment – It refers to the process of assigning both the eigenvalues and eigenvectors of a state matrix to determine the rate of system response decay or growth and the shape of that response, respectively. This assignment is important in practical applications and is governed by specific conditions outlined in relevant theorems.
Eigenvalue – It is a special scalar value which represents the natural frequency, stability limit, or critical threshold of a physical or mathematical system. When a system undergoes a linear transformation, the eigenvectors are the directional axes that do not rotate, and the corresponding eigenvalues determine how much those axes are scaled, stretched, or compressed.
Eigenvalue assignment – It is also known as pole placement. It is a control systems design technique. It involves using state feedback to modify a system’s dynamic properties. By tuning feedback gains, engineers shift the system’s closed-loop eigenvalues to achieve desired stability, responsiveness, and transient performance.
Eigenvalue equation – It is a fundamental linear relationship expressed as ‘A x v = lambda x v’. When a linear transformation (matrix ‘A’) acts on a specific non-zero vector (v), the output vector points in the exact same direction and is only scaled by a constant factor (lambda).
Eigenvalue method – It is a technique used to analyze dynamic systems by linearizing them around an equilibrium point to solve for system state matrices. It calculates eigenvalues (characteristic scalars) and eigenvectors (directional vectors) to reveal fundamental properties such as system stability, natural frequencies, and decay rates.
Eigenvector – It a non-zero vector which does not change direction when a linear transformation (matrix) is applied to it. It only changes in length by a scalar factor called the eigenvalue.
Eigenvector matrix – It is formed by grouping all the eigenvectors of a linear transformation (or system) into a single matrix. It is mainly used to diagonalize complex system matrices, allowing engineers to decouple complex differential equations and simplify structural, electrical, or dynamic analyses.
Eigenvector method – It is also called eigenvector concept. It is governed by the core linear equation ‘A x v = lambda x v’, where ‘A’ is an (n x n) square matrix (the linear transformation), ‘v’ is the eigenvector (the nonzero column vector), and ‘lambda’ is the scalar eigenvalue (the multiplying factor).
Eight disciplines (8D) problem solving process – It is a method for solving of problems in the organization. 8D stands for the 8 disciplines or the 8 critical steps for solving the problems. The eight disciplines are (i) creation of the problem-solving team, (ii) describing of the problem, (iii) implementation of the containment action, (iv) identification and validation of the root cause through root cause analysis, (v) identification and choosing of the corrective action, (vi) implementation of the corrective action and their tracking for effectiveness, (vi) identification and implementation of the preventive action, and (viii) closing and congratulating the team. The process is designed to find the root cause of the problem, devise a short-term fix and implement a long-term solution to prevent recurring problems. It is used mostly by the professionals specially the quality personnel. In the 8D methodology, the main purpose is to identify, correct and eliminate recurring problems. The 8D problem solving process is normally needed (i) when safety or regulatory issues are noticed, (ii) when there are a number of customer complaints which are regularly being received, (iii) when the warranty concerns have indicated greater-than-expected failure rates, and (iv) when internal rejects, waste, scrap, poor performance or test failures are present at unacceptable levels. The model of the 8D problem solving process has four arms namely (i) form, (ii) norm, (iii) storm, and (iv) perform.
Eight-noded quadratic isoparametric element – It is frequently called a serendipity element. It is a 2D finite element used to model complex geometries, featuring four corner nodes and four mid-side nodes. It uses the same quadratic interpolation functions for mapping geometry and approximating displacements, allowing for accurate mapping of curved boundaries.
Einstein’s equation – It normally refers to one of three foundational scientific formulas developed by Albert Einstein, i.e., the famous mass-energy equivalence (E = m x c-square), the Einstein field equations for gravity, or the photo-electric equation.
Einstein relation – It states that mass and energy are interchangeable and are basically two forms of the same thing. It also relates the diffusion coefficient to the mobility and is frequently used in semiconductor device analysis and design. It is also fundamental connection in statistical mechanics and transport theory which states how easily a particle diffuses through a medium is directly proportional to how easily it moves when pushed by an external force (its mobility).
Einstein’s summation convention – It is a notational shorthand where repeated indices in a term implicitly imply summation over the range of that index, omitting the explicit sigma symbol. It makes equations involving vectors, matrices, and tensors much cleaner and easier to read.
Ejection – It is the removal of the compact after completion of the pressing, whereby the compact is pushed through the die cavity by one of the punches. It is also called knock-out.
Ejection force – It refers to the force applied during the ejection process to remove moulded parts from a mould, which can be exerted by mechanisms such as pins or stripper plates. This force is necessary for overcoming the resistance of the moulded part and is distributed effectively, especially in thin-walled components.
Ejection system – It is the mechanism within a mould (such as in injection moulding or die casting) designed to remove a solidified part from the mould cavity after the moulding process is complete. It is the final, critical step in the moulding cycle, designed to apply uniform force to push the part out without causing distortion, drag lines, or cracking. Ejection systems consist of several components which work together to push the part out once the mould opens.
Ejector – It is a device, mechanism, or person that forces, throws, or pushes something out. It is normally used as a type of jet pump to create vacuums or move gases, fluids, and solids by using high-pressure jet streams. It is also device mounted in such a way that it removes or assists in removing a formed part from a die.
Ejector cooling cycle – It is also called ejector refrigeration. It is a thermally driven cooling system which replaces the traditional mechanical compressor with a fluid-driven ejector. It uses thermal energy, such as waste heat or solar power, to compress refrigerant, resulting in vibration-free operation with no moving parts.
Ejector cycle – It is a refrigeration or power system which replaces or assists a traditional mechanical compressor with a fluid-driven ejector. It uses high-pressure fluid (motive vapour) to pull in and compress low-pressure vapour from an evaporator, utilizing pressure energy rather than moving parts.
Ejector efficiency – It measures how effectively an ejector converts the pressure and kinetic energy of a high-pressure ‘motive’ fluid to draw in and compress a lower-pressure ‘suction’ fluid. Since ejector designs vary, performance is defined using three main metrics namely ‘reversible entrainment ratio efficiency (RER), entrainment ratio (ER), and pressure lift efficiency.
Ejector entrainment ratio – It is the ratio of the mass flow rate of the secondary (suction) fluid to the mass flow rate of the primary (motive) fluid in an ejector system. It is a key performance indicator used to evaluate how efficiently a primary fluid can draw and compress a secondary fluid.
Ejector geometry refers to the specific physical dimensions and internal contours of an ejector—a device that uses a high-pressure fluid to pump or compress a lower-pressure fluid. Precise geometric design (nozzle, suction, mixing throat, and diffuser sections) is what determines the device’s operational efficiency, compression ratio, and entrainment ratio.
Ejector half – It is the movable half of a die-casting die containing the ejector pins.
Ejector marks – These marks are surface imperfections (circular / rectangular depressions, raised spots, or white stress marks) left on metal die-castings or plastics when ejector pins push the cooled part out of the mould. These marks occur on non-functional surfaces because of the concentrated ejection force. While frequently inevitable, these marks are managed via optimal cooling, proper pin alignment, and adjusting casting parameters.
Ejector performance – It refers to its efficiency in using a high-pressure motive fluid to draw in, compress, and discharge a lower-pressure secondary fluid. It is primarily quantified by its entrainment ratio, which is the mass flow rate of the suction fluid divided by the motive fluid mass flow rate. The efficiency and overall performance of the device rely on several key operational metrics and characteristics:
Ejector pins – These are high-strength, precision-machined metal rods used in injection moulding and die casting to push solidified parts out of a mould cavity. These pins are designed to withstand high compressive forces, rapid thermal cycling, and wear, typically produced from hardened alloy tool steels or specialized stainless steels.
Ejector plate – It is the movable plate beneath a shell moulding pattern containing the pins for lifting or ejecting the hardened, resin-bonded shell mould from the pattern. It is also known as a push plate or knock-out plate. It is a critical component within a die-casting or injection mould assembly which drives the ejection mechanism to release finished parts. The ejector plate is a moving steel plate located in the ‘B-side’ (moving half) of the mould. Its main purpose is to hold the heads of ejector pins and push them simultaneously to remove the solidified part from the mould core.
Ejector punch – It is a punch used for ejecting compacts.
Ejector refrigeration cycle – It is a thermally-driven cooling system which replaces the traditional mechanical compressor with a fluid-driven ejector. By utilizing heat sources (like solar energy or waste heat), it induces a pressure difference to compress the refrigerant, resulting in highly reliable, vibration-free cooling with no moving parts.
Ejector refrigeration system – It is a heat-driven cooling technology which replaces a traditional mechanical compressor with a static ejector. It uses low-grade thermal energy (like waste heat or solar power) to pump and compress refrigerant vapour, offering the advantages of high reliability, zero moving parts, and low maintenance.
Ejector rod – It is a rod used to push out a formed piece.
Ejector system – It is a mechanism which uses a high-pressure motive fluid (liquid or gas) passing through a nozzle to create a low-pressure zone, which entrains and mixes with a secondary fluid. It acts as a pump without moving parts, relying purely on fluid dynamics (the venturi effect) to pressurize and move materials.
Ejector technology – It is a passive, fluid-dynamic system which uses a high-pressure motive fluid to draw, compress, and transport a lower-pressure fluid. By utilizing the venturi effect, it eliminates moving parts, creating simple, reliable mechanisms for vacuum generation, refrigeration, pumping, and industrial gas compression.
Ekelund formula – It is also called Ekelund ranging. It is a passive sonar technique used in ‘target motion analysis’ (TMA) to estimate the range (R) of a target vessel by observing changes in bearing while the observer vessel performs a maneuver (typically a ‘2-leg-1-zig’ scenario). It determines range based on bearing rates (B) and relative speeds before and after a course change. The Ekelund range is defined by dividing the difference in the observer’s speed across the line of sight (LOS) by the difference in bearing rates between two legs of a maneuver.
Ekman layers – These are boundary layers in which there is a balance between the viscous force and the Coriolis acceleration. They are typically quite thin. Ekman layers occur both in the atmosphere and in the ocean. There are two types of Ekman layers.
Elastic analysis – It refers to two distinct methodologies depending on your field. It evaluates how structures respond to loads assuming materials return to their original shape once the load is removed. In economics, it measures how sensitive one economic variable is to changes in another.
Elastic and plastic deformation – It refers to the two distinct processes metals undergo when subjected to tensile or compressive loading. Elastic deformation occurs when stresses are below the proportional limit, involving atoms being stretched or compressed without permanent displacement, while plastic deformation happens when stresses exceed a critical level, resulting in permanent atomic movement mainly through dislocation motion.
Elastic beam – It is a structural element that temporarily deforms (bends, twists, or stretches) under an applied load and completely returns to its original shape and size once the load is removed.
Elastic bending – It is the temporary, reversible deformation of a beam or structural member under load, where it curves without permanent damage. It follows Hooke’s law, meaning the bending moment is proportional to the curvature, and the material returns to its original shape once the load is removed.
Elastic buckling analysis – It is an assessment used to determine the critical loads at which a slender structure suddenly deflects laterally under compression. It assumes the material remains within its linear-elastic range (Hooke’s law) and that deformations are small, utilizing eigenvalue solutions to find theoretical failure points.
Elastic buckling stress – It is the specific compressive stress at which a slender structural member (like a column or plate) suddenly bows or deflects laterally, losing its stability. Crucially, this failure occurs while the stress remains within the material’s elastic limit, meaning the member will spring back to its original shape if the load is removed.
Elastic calibration device – It is a device for use in verifying the load readings of a testing machine consisting of an elastic member(s) to which loads can be applied, combined with a mechanism or device for indicating the magnitude (or a quantity proportional to the magnitude) of deformation under load.
Elastic chuck – It is a specialized work-holding device used in machining and precision manufacturing which uses an elastic or flexible component, such as spring steel, rubber, or a diaphragm, to clamp a work-piece or tool. Unlike traditional, rigid jaw chucks, elastic chucks offer high precision, self-centering capabilities, and superior handling of thin-walled, fragile, or irregular parts without distortion.
Elastic coefficient – It is also called modulus of elasticity. It is the ratio of stress to strain for a material within its elastic limit. It quantifies a material’s stiffness, meaning its ability to resist elastic deformation when subjected to an applied force.
Elastic compliance – It is a condition under which two bodies in contact, which are subjected to a force, undergo small elastic displacement without slip. It is a mechanical property defined as the degree to which a material deforms elastically when subjected to an applied force. It is the exact reciprocal of stiffness (or elastic modulus). A highly compliant material deforms easily and recovers its original shape once the load is removed.
Elastic composite – It is an engineered material consisting of a stiff reinforcing phase (like fibres or particles) embedded in a softer matrix (like polymers or metals). When subjected to mechanical loads, it deforms reversibly, fully recovering its original shape and size once the load is removed.
Elastic compression – It refers to the temporary reduction in volume or length of a material or component caused by applied balanced inward forces, which is fully recovered once the force is removed. It is a form of elastic deformation where the material behaves as a spring, storing potential energy rather than permanently deforming (plastic deformation) or failing.
Elastic constants – These are the factors of proportionality which relate elastic displacement of a material to applied forces. Examples are bulk modulus of elasticity, modulus of elasticity, Poisson’s ratio, and shear modulus.
Elastic constitutive relation – It is an equation which defines the mechanical behaviour of a material by linking applied stresses to resulting strains. Specifically for an elastic material, this relationship is uniquely defined, fully reversible, and independent of the loading history, meaning the material returns to its original dimensions when the load is removed.
Elastic contact – It refers to the deformation of solid surfaces in contact under high pressure, allowing for elastic deflection to accommodate the load. This phenomenon is substantial in regimes such as elasto-hydrodynamic lubrication, where it plays an important role in maintaining a continuous fluid film between contacting surfaces.
Elastic core – It refers to the central portion of a structural component or material which remains entirely in an elastic state, even when the outer layers have yielded to plastic deformation.
Elastic crack tip – It is the singular point at the end of a crack within a continuum, where localized stress approaches infinity (sigma -> infinity) as the distance from the tip goes to zero (r -> 0), characterized by a sharp, highly concentrated stress field described by linear elastic fracture mechanics (LEFM).
Elastic curve – It is the curved line formed by the longitudinal centroidal axis of a beam or shaft after it deflects under an applied load. It is a visual and mathematical representation of how structural members deform within their elastic limits.
Elastic cushion – It is a shock-absorbing or pressure-distributing mechanical layer made of elastomeric materials (like poly-urethane, rubber, or silicone). It temporarily deforms under load and returns to its original shape, reducing vibrations, preventing surface damage, and ensuring uniform force distribution in manufacturing, civil, and structural engineering.
Elastic cylinder – It refers to a cylindrical component or geometric model which deforms under an applied load (such as tension, compression, or fluid pressure) but fully returns to its original shape and dimensions once the load is removed.
Elastic deflection – It is the temporary, recoverable curvature or displacement of a structural member (like a beam) from its original position, caused by applied loads which produce small, elastic strain at the material’s surface. The structure returns to its original shape upon unloading, governed by Young’s modulus, bending moment, and cross-sectional geometry.
Elastic deformation – It is the temporary, reversible change in shape or size of a material under applied force. It occurs when stresses are below the material’s yield point, causing atomic bonds to stretch rather than slip. Once the load is removed, the material returns to its original dimensions.
Elastic design – It is a methodology where structural members are sized so that calculated working stresses remain well below the material’s elastic limit and yield strength. Under maximum expected loads, the material shows linear stress-strain behaviour, meaning it completely returns to its original shape once the load is removed.
Elastic distribution – It very frequently refers to how internal forces (like stresses or bending moments) spread throughout a structure based on linear-elastic material behaviour, where deformations are fully reversible and obey Hooke’s law.
Elastic domain – It is the specific range of stress within which a material deforms reversibly. When an applied load is removed, the material perfectly returns to its original shape and size without any permanent, plastic deformation.
Elastic electron scatter – It is the scatter of electrons by an object without loss of energy. It is normally an interaction between electrons and atoms.
Elastic energy – It is the quantity of energy needed to deform a material within its elastic range of behaviour, neglecting small heat losses because of the internal friction. The energy absorbed by a sample per unit volume of material contained within the gauge length being tested. It is determined by measuring the area under the stress-strain curve up to a specified elastic strain.
Elastic expansion – It refers to a temporary, reversible increase in the dimensions or volume of a material or component caused by external forces (such as internal pressure) or temperature changes. When the applied load or heat is removed, the material perfectly snaps back to its original size and shape.
Elastic fabric – It is a textile material engineered to undergo reversible deformation, meaning it can stretch under tension and immediately recover its original dimensions once the load is removed.
Elastic force – It is the internal restoring force exerted by a material when it is deformed (stretched or compressed) which drives it to return to its original shape. It acts in the opposite direction of the applied deformation force.
Elastic half-space – It is a foundational theoretical model used to analyze how materials, like soils, rocks, or structural metals, deform under applied loads. It represents a 3D solid which is infinite in two horizontal directions and infinitely deep, but bounded by a single flat surface (the half-space).
Elastic hysteresis – It is a misnomer for an anelastic strain which lags a change in applied stress, hence creating energy loss during cyclic loading. It is more properly termed mechanical hysteresis.
Elastic interaction – It refers to forces, collisions, or stresses where bodies deform under load and completely return to their original shape once the load is removed (with no permanent deformation). No kinetic energy or mechanical energy is lost as heat. Elastic interactions are because of the modifications in the geometric structure of the substrate due to the presence of an adsorbate.
Elasticity – It is the property of a material by virtue of which deformation caused by stress disappears upon removal of the stress. A perfectly elastic body completely recovers its original shape and dimensions after release of stress.
Elasticity equations – These equations refer to the set of mathematical formulations used to describe the behaviour of materials under small strains in three-dimensional applications, normally utilized in engineering contexts. These equations can be simplified for specific two-dimensional situations and are foundational for understanding linear elasticity.
Elasticity matrix – It is also called stiffness matrix,. It is a mathematical representation used to relate stress (force per unit area) to strain (deformation) in a linear elastic material. It defines how stiff a material is and dictates how it will deform when subjected to external loads.
Elasticity problem – It involves analyzing how a solid object deforms, bends, or stretches when external forces (like pressure, weight, or tension) are applied. It refers to the study of how a material deforms under physical forces and returns to its original shape. It also evaluates how flexible buyers and sellers are to changes in market conditions, normally defined as the percentage change in one variable divided by the percentage change in another. It is the economic measurement of how consumer demand or supply changes in response to variables like price.
Elasticity theory – It is the study of the deformation of a body under the influence of stresses, body forces, and surface forces, which aims to determine the deformation function which describes how a material changes shape in response to these applied forces.
Elastic limit – It is the maximum stress which a material is capable of sustaining without any permanent strain (deformation) remaining upon complete release of the stress. A material is said to have passed its elastic limit when the load is sufficient to plastic, or non-recoverable, deformation.
Elastic matrix – It is frequently called an elasticity or stiffness matrix. It is a mathematical array used in solid mechanics and finite element analysis (FEA) to relate stresses to strains within an elastic, deformable material.
Elastic mechanism – It refers to a physical system which achieves specific movement, shape-morphing, or force transmission through the elastic deformation of its own materials rather than relying on traditional rigid, jointed parts (like pins or hinges).
Elastic membrane – It is a thin, flexible structural element which cannot resist bending or compression, but can support tensile (stretching) forces. It maintains its structural integrity mainly by stretching and tension across its surface, acting much like a soap film or a drumhead.
Elastic mode – It refers to a specific natural frequency and its corresponding deformation shape (eigenvector) at which a flexible structure deforms when subjected to dynamic loads. It describes the inherent, flexible ways an object (like a bridge, or a tall building) bends or twists when vibrating. The term is frequently used to describe the first phase of a material’s stress-strain curve, defined by its elastic modulus (e.g., Young’s modulus). It is the operational state where a material deforms under an applied load but completely returns to its original shape and dimensions once the load is removed. In this mode, interatomic bonds are stretched rather than permanently displaced (which results in plastic deformation).
Elastic model – It is a framework which defines how a material deforms under a load and completely returns to its original shape once the load is removed. It represents the simplest form of material behaviour, assuming no permanent (plastic) deformation occurs.
Elastic modulus – It is same as modulus of elasticity. It is the measure of rigidity or stiffness of a material. It is the ratio of stress, below the proportional limit, to the corresponding strain.
Elastic moment – It is the maximum bending moment a structural member (like a beam) can withstand before the material begins to yield (permanently deform). It represents the limit of purely elastic behaviour, where the member returns to its original shape once the load is removed.
Elastic optical network – It is an advanced optical transport network which dynamically allocates spectrum in variable-width frequency slots to match specific connection needs. Unlike rigid, fixed-grid networks, Elastic optical networks (EONs) use a flexible grid to provide highly efficient band-width utilization and distance-adaptive modulation.
Elastic-plastic analysis – It is a method which evaluates how structures behave under loads which exceed the material’s elastic limit. It accounts for both fully recoverable (elastic) and permanent (plastic) deformations, enabling engineers to design more economical structures by utilizing reserve post-yield strength.
Elastic-plastic bending – It is the process where a structural member, typically made of ductile material (like steel), is loaded beyond its elastic limit, causing simultaneous elastic deformation at the core and permanent (plastic) deformation at the outer fibres. It involves non-linear stress distribution and provides higher loading capacity than purely elastic design.
Elastic-plastic boundary – It is the specific interface within a material which separates the zone undergoing recoverable, temporary deformation from the zone experiencing permanent, irreversible deformation. It physically marks the exact location where the applied stress reaches the material’s yield strength.
Elastic-plastic fracture mechanics – It is an framework used to evaluate structures containing cracks or flaws where substantial plastic (permanent) deformation occurs at the crack tip. It bridges the gap for ductile materials which cannot be accurately analyzed using traditional linear elastic fracture mechanics (LEFM).
Elastic-plastic material model – It describes materials which deform reversibly (elastic) under low loads, but undergo permanent deformation (plastic) once a specific yield threshold is exceeded. It is an important constitutive framework used in structural analysis and finite element modeling (FEM) to simulate material yielding, load-bearing limits, and structural failure.
Elastic-plastic model – It is a constitutive equation defining initiate a material which deforms reversibly under low stress (elastic behaviour) and permanently once a yield threshold is exceeded (plastic behaviour). It simulates permanent material flow, residual stresses, and hardening in metal forming and high-stress applications, combining Hooke’s law with yield surfaces (e.g., von Mises).
Elastic-plastic rolling contact – It is an analysis of two surfaces rolling against each other (e.g., bearings, gears, wheels) where localized contact pressure exceeds the material’s yield strength, causing both recoverable elastic deformation and permanent plastic deformation. This behaviour is critical for modelling, predicting material shakedown, and analyzing fatigue damage in high-load applications.
Elastic-plastic time-independent model – It is a framework used to predict the behaviour of materials which deform reversibly (elastically) under low loads and permanently (plastically) under higher loads, where the behaviour does not depend on the rate of loading. This model assumes that loading occurs instantly or slowly enough that time-dependent effects (like creep or viscosity) are negligible.
Elastic plate – It is a structural element characterized by planar dimensions (length and width) which are considerably larger than its thickness. It behaves elastically, meaning it deforms under transverse loads but fully recovers its original shape when the loads are removed.
Elastic power – It is the required force needed to stretch an elastic material (like a compression bandage or fabric) to a predetermined length, determining the pressure it exerts. It is broadly associated with elastic potential energy, which is the mechanical energy stored when an object is elastically deformed.
Elastic range – It is also called elastic region. It is the initial phase of a material’s stress-strain curve where it deforms under load but fully returns to its original size and shape once the stress is removed. Within this boundary, the material behaves like a spring, following a linear and proportional relationship known as Hooke’s law.
Elastic ratio – It is the yield point divided by tensile strength.
Elastic recovery – It is the quantity the dimension of a stressed elastic material returns to its original (unstressed) dimension on release of an applied load. In hardness testing, the shortening of the original dimensions of the indentation upon release of the applied load.
Elastic regime – It is the initial phase of a material’s deformation where it stretches or bends under an applied load, but fully returns to its exact original shape and size once that load is removed.
Elastic region – It is the initial phase of a material’s deformation where it completely returns to its original shape and size once an applied load is removed. Within this zone, the atomic bonds are stretched but not permanently broken.
Elastic residual strain – It is the portion of deformation remaining in a material after external loads are removed, caused by internal, self-equilibrating stresses. It results from non-uniform plastic deformation, such as during manufacturing processes like welding, machining, or heat treatment, where adjacent material areas constrain expansion or contraction.
Elastic resilience – It is the quantity of energy absorbed in stressing a material up to the elastic limit, or it is the quantity of energy which can be recovered when stress is released from the elastic limit.
Elastic response – It is a material’s ability to instantly deform under a load and completely return to its original size and shape as soon as that load is removed. It is a reversible, non-permanent deformation characterized by a linear relationship between stress and strain.
Elastic scattering – It is the collisions between particles that are completely described by conservation of energy and momentum.
Elastic section modulus – It is a geometric property used to calculate a beam’s resistance to bending before it yields. It indicates how effectively the cross-sectional shape distributes material to handle applied bending moments.
Elastic solid – It is a deformable material which completely recovers its original size and shape once the external forces causing deformation are removed. In this state, the material’s atoms temporarily displace but return to their stable equilibrium positions through interatomic restoring forces.
Elastic solution – It is a theoretical framework used to calculate how materials, structures, or soils deform under applied loads while strictly remaining within their elastic limits. These solutions predict stress and strain, ensuring that once the load is removed, the system returns entirely to its original shape.
Elastic stiffness – It is the ability of an object or material to resist elastic deformation, stretching or bending, when subjected to an applied force. It measures how much force is needed to cause a unit of displacement, meaning the material returns entirely to its original shape and size once the force is removed.
Elastic strain – It is a change in dimensions directly proportional to and in phase with an increase or decrease in applied force.
Elastic strain energy – It is the energy expended by the action of external forces in deforming a body elastically. Basically, all the work performed during elastic deformation is stored as elastic energy, and this energy is recovered upon release of the applied force.
Elastic strain rate – It is the time rate of change of reversible, non-permanent deformation in a material. It represents how fast bonds stretch or contract within the elastic limit and is measured in inverse seconds. It differs from plastic strain rate, as it relates to temporary deformation which vanishes upon unloading.
Elastic stress – It is the internal resistance force per unit area which a material develops while undergoing reversible, temporary deformation. If the applied load is removed, the material snaps back to its original shape. It acts as the driving force behind a material’s natural tendency to recover its initial state.
Elastic stress concentration – It is a phenomenon where the localized stress at a structural discontinuity (like a hole, notch, or sharp corner) is considerably higher than the average stress in the surrounding material. It occurs when geometry changes disrupt the uniform flow of stress, causing lines to crowd together.
Elastic stress concentration factor – It is a dimensionless value used ito quantify how much stress is amplified at structural discontinuities (such as holes, fillets, or notches) compared to the surrounding material.
Elastic stress field – It is the mathematical and spatial distribution of internal resisting forces within a solid material during linear elastic deformation. When external loads are applied, it describes how these forces (both normal and shear) vary continuously from point to point, obeying Hooke’s law so that the material returns to its original shape upon unloading.
Elastic stress-strain relation for a mixture – It describes how a composite material (or mixture of materials) deforms under load and returns to its original shape upon unloading. It establishes that, within the elastic limit, the internal stress (sigma) is directly proportional to the strain (epsilon) produced, typically following a generalized Hooke’s law.
Elastic strip – It refers to a continuous, flat piece of elastic material (like spring steel, rubber, or composites) designed to undergo reversible deformation. It stores mechanical energy when stretched or bent and completely returns to its original dimensions once the applied load is removed.
Elastic structure – It is a type of structure which can deform under applied loads and return to its original shape upon the removal of those loads.
Elastic support – It is a boundary condition where a structure is restrained by flexible members rather than a rigid, unyielding anchor. It provides a spring-like resistance to deformation, where the reaction force is directly proportional to the displacement. It allows engineers to simulate real-world compliance in finite element analysis (FEA) using a stiffness coefficient (k) expressed as ‘k =F/d’, where ‘F’ is the applied force (or pressure), and ‘d’ is the resulting deflection.
Elastic tension – It refers to the internal pulling force (stress) generated within a solid material when it is subjected to uniaxial loading, stretching or elongation, within its elastic limit. This deformation is temporary and fully recoverable, meaning the material returns to its original dimensions once the tensile load is removed.
Elastic theory – It is a branch of solid mechanics which studies how materials deform under stresses, such as forces or temperature changes, and return to their original shape upon removal of that load. It predicts the deformation, strain, and stress in structural elements, ensuring they remain within safe limits, typically assuming linear behaviour per Hooke’s law.
Elastic twist – It is the temporary, recoverable angular deformation of a structural member (like a shaft or wing) when subjected to a torsional load. Since the deformation is elastic, the component completely returns to its original, untwisted state once the applied torque or aerodynamic force is removed.
Elastic variable – It normally refers to a specific metric or parameter which is highly adaptable and responsive to changing conditions. Its exact definition depends on the context: In systems and software engineering, it is a dynamic variable whose capacity or size automatically scales up or down based on workload, data volume, or resource demand (e.g., cloud resource allocation). In case of materials and mechanical engineering, it is a parameter which defines how a material deforms and returns to its original dimensions when stress is applied and removed. This encompasses variables like the modulus of elasticity, which defines stiffness, and strain, which measures deformation
Elastic-visco-plastic (EVP) constitutive model – It is a framework describing materials which show time-dependent, permanent deformation. It combines instantaneous elasticity (recoverable deformation) with rate-dependent plastic flow (permanent, non-instantaneous deformation).
Elastic-visco-plastic stress-strain matrix – It is a constitutive formulation used in engineering, mainly within finite element analysis (FEA), to model materials which show both rate-dependent plasticity (visco-plasticity) and recoverable elasticity. Unlike rate-independent plastic models, this matrix updates the stress-strain relationship based on the speed of loading, frequently used for polymers, metals at high temperatures, and soils.
Elastic wave – It is a mechanical disturbance which propagates through a material, causing particles to oscillate about their equilibrium without permanent deformation or net mass transfer. Energy travels through atomic / molecular bonds. Once the wave passes, the material returns to its original state.
Elastic wave propagation – It is the transmission of mechanical energy through a deformable medium through particle vibration, without causing permanent material deformation. As the wave passes, particles oscillate about their equilibrium and return to their original position once the wave has passed, obeying Hooke’s law.
Elastic yarn – It is a composite textile engineered with high stretch and rapid recovery, capable of elongating 300 % to 500 % before returning to its original state. It is chiefly engineered by combining an elastomeric core with inelastic fibres (e.g., cotton or polyester) to provide both elasticity and durability.
Elastic zone – It is also called elastic region. It is the phase of material deformation where a component temporarily stretches, compresses, or bends under an applied load, but fully recovers its original shape and dimensions once the load is removed.
Elasto-hydro-dynamic lubrication – It is a condition of lubrication in which the friction and film thickness between two bodies in relative motion are determined by the elastic properties of the bodies, in combination with the viscous properties of the lubricant at the prevailing pressure, temperature, and rate of shear.
Elastomer – It is a natural or synthetic polymer, which at room temperature can be stretched repeatedly to at least twice its original length, and which after removal of the tensile load immediately and forcibly returns to approximately its original length.
Elastomer compatibility (sealing materials) – One important requirement for hydraulic fluids is that they are to be compatible with sealing materials and hydraulic hoses. The optimum in order for the hydraulic system to remain sealed is a moderate swelling (2 %). One of the most common materials in hoses (internal) and gaskets is nitrile rubber (NBR). Several other materials are used in hydraulic systems, which include fluoro-rubber (FPM with the trade name Viton), polyester urethane (AU) and polyether urethane (EU). Materials which are not suitable include natural rubber, polychloroprene (neoprene) and isobutylene isoprene.
Elastomer-epoxies – These are frequently called elastomer-modified epoxies or rubber-toughened epoxies. These are advanced polymeric materials created by blending rubbery, elastic polymers with rigid, high-strength epoxy resins. This approach combines the stiffness and chemical resistance of base epoxies with the flexibility and crack-resistance of elastomers, resulting in a considerably tougher material.
Elastomeric adhesives – These are the materials based on synthetic or naturally occurring polymers which show superior toughness and elongation. They are characterized by high flexibility and superior peel strength, making them suitable for bonding lightweight materials in unstressed joints, although they cannot be considered structural adhesives.
Elastomeric coatings – These are fluid-applied roofing membranes with elastic properties that allow it to expand and contract with the substrate. Elongation is important because roofs expand and contract and this allows the roof coating to move with the substrate.
Elastomeric couplings – In general, these couplings obtain their flexibility from stretching or compressing a resilient material (rubber, plastic, etc.). Some sliding or rolling can take place, but it is normally minimal.
Elastomeric flexible coupling – These couplings typically utilize a plastic or rubber element that allows for the temperature growth or axial movement. The elastomeric element is sufficiently resistant to fatigue failure to provide an acceptable life compared to the cost of the coupling. Majority of the elastomeric flexible couplings do not use lubrication, and are loaded in shear.
Elastomeric matrix – It is a continuous polymer base (like silicone, poly-urethane, or rubber) which provides structural integrity, flexibility, and high elongation in a composite material. It holds reinforcing fibres or particles in place, allowing the composite to reversibly stretch and absorb impact.
Elastomeric tooling – It is a tooling system that uses the thermal expansion of rubber materials to form composite parts during cure. It uses rubber details to generate needed moulding pressure or to serve as a pressure intensifier during composite-part curing cycles. The rubber is made from castable room-temperature vulcanized (RTV) rubber compounds or calendered silicone rubber sheets (reinforced and unreinforced) in ‘B’ stage form (fully compounded but uncured).
Elastoplastic behaviour – It describes materials which show both reversible elastic deformation at low stress and irreversible, permanent plastic deformation once they exceed a specific yield strength. This non-linear response involves an initial linear stress-strain relationship, followed by permanent, non-linear deformation, important for modeling structural integrity.
Elasto-plastic rolling contact – It is a complex mechanical interaction where surfaces, such as gears or bearings, experience stresses exceeding their yield strength, resulting in a combination of elastic deformation (reversible) and plastic deformation (permanent) during cyclic loading. It involves substantial residual stresses, surface fatigue, and non-linear material behaviour.
Elasto-static problem – It is a scenario in which the governing equations describe the relationship between displacement, strain, and stress within a material, subject to specific boundary conditions, and involves finding a unique solution which satisfies these equations and conditions.
Elasto-visco-plastic (EVP) behaviour – It is a complex material response which combines three distinct rheological properties namely elasticity, viscosity, and plasticity. These materials function as non-Newtonian ‘yield stress’ fluids, meaning they behave as elastic solids at low stresses and flow as viscous liquids once a critical yield stress threshold is surpassed.
Elasto-visco-plastic (EVP) constitutive equation – It defines the stress-strain relationship for materials showing instantaneous elastic response, rate-dependent viscosity, and plastic yielding (irreversible deformation). These models additively decompose strain rates into elastic and visco-plastic components, typically expressed as e = e(e) + e(vp), allowing for the simulation of creep, relaxation, and permanent deformation.
Elasto-visco-plastic (EVP) stress model – It is a constitutive framework in mechanics which describes materials showing three simultaneous behaviours namely elasticity (recoverable deformation), viscosity (time-dependent flow), and plasticity (permanent deformation after yielding). These models are important for simulating complex materials, such as polymers, foams, gels, and rock, which behave like solids below a certain yield stress and flow like liquids above it.
Elbow – It is a pipe fitting which is installed between two lengths of pipe or tube allowing a change of direction, normally 90-degree or 45-degree. The ends can be machined for butt welding, threaded (normally female), or socketed, etc. When the two ends differ in size, it is called a reducing or reducer elbow. Most elbows are available in short radius or long radius of types. It is also a part of tuyere stock of a blast furnace. At the elbow, hot air blast takes 90-degree turn. Elbows have peep sight for watching inside the furnace.
E-learning – It encompasses the delivery of technical education, training, and skill development using digital media and network technologies. It applies instructional design principles to engineering curricula, such as CAD / CAM (computer-aided design / computer-aided manufacturing) simulations, virtual laboratories, and interactive modules, allowing learners to master complex concepts flexibly and remotely.
Electret – It is a dielectric material which permanently retains an impressed electric field. It is the dual to a magnet. Electret holds a quasi-permanent electrical charge or polarization. The term is a portmanteau of electricity and magnet. An electret is the electrostatic equivalent of a permanent magnet. [
Electric – It refers to anything powered by, relating to, or producing electricity, such as an electric motor or electric current. It describes devices operated by electric energy. It is frequently used for specific devices (e.g., electric actuator), while electrical applies to general topics (e.g., electrical engineering).
Electric actuation – It is the process of using electrical energy (through motors, solenoids, or piezoelectric materials) to generate mechanical motion or force. It converts electrical signals into physical action, offering precise control over speed, position, and torque across industrial applications.
Electric actuators – These actuators typically use standard motors, powered by either alternating current induction, direct current, or capacitor-start split-phase induction. The motor is connected to a gear or thread which creates thrust to move the valve. As a fail-safe, some motors are equipped with a lock in last position on its gear. This means that the gear cannot move from forces outside of the electric motor. This helps prevent overshoot on the motor as well as helps create better positioning for the gear.
Electrical and electronic equipment – It refers to any device dependent on electric currents or electro-magnetic fields to function properly, typically operating with a voltage rating not exceeding 1,000 volts AC (alternating current) or 1,500 volts DC (direct current). It includes equipment for generating, transferring, or measuring these currents, relying on plugs, batteries, or antennas.
Electrical and electronic industry – It is a huge manufacturing sector responsible for designing, producing, and distributing devices which generate, distribute, use, or control electrical energy. It covers everything from heavy power equipment to micro-electronic components and consumer gadgets, with electrical devices converting power and electronic devices regulating electron flow.
Electrical bandwidth – It is the specific range of frequencies over which an electronic circuit, amplifier, or transmission channel can effectively process or transmit signals. It is measured in hertz (Hz) and represents the difference between the highest and lowest usable frequencies in a given continuous band.
Electrical battery – It is a device which stores energy in chemical form and converts it into electricity. It is built from one or more electrochemical cells which release direct current (DC) power on demand to operate devices, vehicles, and power grids.
Electrical box – It is a protective enclosure used to safely house and organize electrical connections, wiring, and devices (such as switches and outlets). It protects wires from damage, prevents accidental contact to avoid electric shocks, and contains sparks or short-circuit faults to prevent fire hazards.
Electrical cable – It is a flexible conducting wire to carry electrical power or signals, normally covered with an insulating material.
Electrical circuit – It is an arrangement which facilitates the flow of electricity, allowing for the application of electrical energy through components governed by basic variables such as charge, current, voltage, and resistance.
Electrical codes – These are standardized rules and regulations designed to ensure the safe design, installation, and maintenance of electrical wiring and equipment. Their main purpose is to protect people and property by preventing hazards like fires and electric shocks. These are a set of regulations for the use of electricity. They can vary from local to international in scope.
Electrical conditions – These conditions normally refer to the physical state and safety compliance of a property’s wiring and electrical systems, or a specific operating state. These conditions refer to the specifications governing the electric field in piezoelectric materials, including the absence of surface charges on non-electrode surfaces and the known potential or charge on surfaces covered with electrodes. These conditions help define the behavior of the electric field in the system.
Electrical conductance (G) – It measures how easily electric current flows through a material or component, acting as the reciprocal of electrical resistance (R), where ‘G = 1/R’. It represents the ease of charge flow, measured in Siemens (S), frequently called mho or 1/omega. High conductance means low resistance, facilitating easy current passage.
Electrical conductivity – It is the capacity or a measure of a substance’s ability to conduct an electric current. This capacity is expressed as a percentage of the International Annealed Copper Standard (IACS), which has a resistivity of 1/58 ohm-mm2/m (ohm square millimeter/metre) at 20 deg C and an arbitrarily designated conductivity of unity.
Electrical conductor – It is an object which carries an electric current, with little loss.
Electrical contact – It is a separable part of an electric device which carries current when touching another contact.
Electrical contact materials – These materials make and break electrical circuits. Contacts are made of either elemental metals, composites, or alloys which are made by the melt-cast method or produced by powder metallurgy processes. Powder metallurgy facilitates combinations of metals which ordinarily cannot be achieved by alloying. A majority of contact applications in the electrical industry utilize silver-type contacts, which include the pure metal, alloys, and powder metal combinations. Silver, which has the highest electrical and thermal conductivity of all metals, is also used as a plated, brazed, or mechanically bonded overlay on other contact materials, notably, copper and copper-base materials. Other types of contacts used include the platinum group metals, tungsten, molybdenum, copper, copper alloys, and mercury. Aluminum is normally a poor contact material since it oxidizes readily, but is used in some contact applications because of its good electrical and mechanical properties and its availability and cost.
Electrical control panels – These panels are enclosures fabricated out of steel sheet metal. They provide and control electric power to equipment and appliances. Provision for indicating electrical parameters like voltage, current, frequency, and power factor etc. are required to be available on the face of the panel. Regulation of the power supply is also possible with the help of auto transformer switches and circuit breaker. These panels are designed and used to control mechanical equipment. Each one is designed for a specific equipment arrangement and includes devices which allow an operator to control specified equipment. Electrical panel components control every piece of equipment in several industries.
Electrical control panel descriptions – These descriptions are the terms and attributes which are used to describe the panels. An example of how to describe important control panel attributes is (i) safety ratings such as third-party safety certification, and SCCR, (ii) enclosure ratings such as NEMA (National Electrical Manufacturers Association) rating, (iii) material of construction such as 304 grade stainless steel, (iv) mounting such as wall mount or floor mount, (v) door mechanism such as lockable handle with three point door latch, (vi) main power both incoming power e.g., 440 V three-phase through a main circuit breaker, and outgoing power, (vii) control Power such as 110 V AC or 120 V AC and 24 V DC, (viii) door mounted operator devices, (viii) sequence of operation, and (ix) remote control interface.
Electrical control panel design – Designing of the industrial control panels can be a complex process, because of the need to meet all applicable regulatory standards and safety requirements. Developing the design matrix (DM) needs identification of user requirements. For the control panel of the automated modular construction machine, the user requirements include (i) to provide a 110 volts AC (alternating current) or 120 volts AC / 24 volts DC (direct current) control panel, (ii) to conform to standards, and (iii) to conform to best practices. All other requirements, such as maintainability, safety, and prevailing guidelines, which are included in these user requirements, comprise the high-level functional requirements (FRs). These requirements can be combined into one main requirement, which is to build a 110 volts AC (alternating current) or 120 volts AC / 24 volts DC (direct current) control panel.
Electrical deposition – It is a process in which metallic coatings are formed by depositing metallic ions onto a cathode in an electrolyte solution, facilitated by an electrical circuit which includes a positive electrode. The structure and properties of the deposited metal are influenced by factors such as the chemical composition of the electrolyte, temperature, pH, and electrical current density.
Electrical device – It is an apparatus or tool which operates by utilizing electrical energy. It functions by converting this electricity directly into another form of energy, such as heat, light, or mechanical movement.
Electrical discharge – It is the sudden, rapid flow of electric current through a normally non-conductive medium, such as air or a gas. It occurs when a build-up of electric potential (voltage) becomes so high that it ionizes the medium, turning it into a temporary conductor to release stored energy and restore electrical balance.
Electrical discharge grinding – It consists of grinding by spark discharges between a negative electrode grinding wheel and a positive work-piece separated by a small gap containing a dielectric fluid such as petroleum oil.
Electrical discharge machining – It is the metal removed by a rapid spark discharge between different polarity electrodes, one on the work-piece and the other the tool separated by a gap distance of 0.013 millimeters to 0.9 millimeters. The gap is filled with dielectric fluid and metal particles which are melted, in part vapourized, and expelled from the gap. It is also called spark erosion. It is a non-traditional manufacturing process which shapes conductive materials using high-frequency electrical sparks, rather than mechanical force. It removes material through heat-based, localized erosion, making it ideal for creating complex, precise geometries, deep cavities, or, in particular, cutting extremely hard materials like tungsten carbide which are difficult to machine conventionally.
Electrical discharge milling – It is a non-traditional, thermal-based manufacturing process which removes material from electrically conductive materials using, specifically, a rotating cylindrical electrode to cut, shape, or sink cavities. It is a form of electro discharge machine (spark erosion) where sparks are generated by electrical pulses between the rotating tool and work-piece, separated by a dielectric fluid.
Electrical discharge texturing – It is a low-cost, precision-controlled surface texturing technique using electrical sparks to create specific surface micro-topographies on conductive materials like steel rolls. It is a variant of electrical discharge machining (EDM), a non-traditional machining process.
Electrical discharge wire cutting – It is a special form of electrical discharge machining wherein the electrode is a continuous moving conductive wire. It is also referred to as traveling wire electrical discharge machining.
Electrical disintegration – It is the metal removal by an electrical spark acting in air. It is not subject to precise control, the most common application being the removal of broken tools such as taps and drills.
Electrical dissipation factor – it is the ratio of the power loss in a dielectric material to the total power transmitted through it. Hence, there is the imperfection of the dielectric. It is equal to the tangent of the loss angle.
Electrical distribution – It is the process of delivering electricity from the source (like a power plant) to the end user. It involves a network of power lines, transformers, and other equipment to transport and convert electricity at the appropriate voltage and current.
Electrical domain – It is the realm of electrical parameters, circuits, and signals. It encompasses physical and theoretical systems where electricity, such as voltages, currents, and power, flows through components like resistors, capacitors, and inductors.
Electrical double layer – It is a structure which forms near a charged surface in a fluid, consisting of a Stern layer of counter ions adsorbed to the substrate and a diffuse layer of ions attracted by the Coulomb force, which screens the first layer and can move within the fluid.
Electrical effect – It refers to any observable physical or chemical phenomenon resulting from the presence, motion, or interaction of electric charges. When electricity flows or builds up, it produces several practical and scientifically substantial effects. The main electrical effects can be categorized as heating effect, magnetic effect, chemical effect, mechanical effect, physiological effect, and specialized physical effects such as photo-electric effect and piezo-electricity.
Electrical-electronic control – It is a system which uses sensors, micro-processors, and power components to monitor, manage, and regulate the behaviour of machines, devices, or processes. It converts physical inputs (temperature, pressure) into electrical signals to drive actuators, ensuring precise operation in applications like industrial automation, and electronic control units (ECUs).
Electrical element – In circuit theory, it is a node at which some electrical property is concentrated (e.g., resistance, etc.).
Electrical enclosure – It is a cabinet or box which protects electrical or electronic equipment and prevents electrical shock. Enclosures are normally made from rigid plastics or such metals as steel, stainless steel, or aluminum.
Electrical energy – It is the power derived from the movement of charged particles (like electrons) through a conductor. It is a form of kinetic energy which results from work done by an electric field on charges. It powers our daily lives and easily converts into heat, light, and motion.
Electrical engineering – It is that branch of engineering which deals with the application of electricity to practical issues.
Electrical equipment – It is a device for the generation, transmission, or utilization of electric power.
Electrical generating station – it is also called a power plant or power station. It is an industrial facility which converts different forms of energy (such as chemical, nuclear, kinetic, or solar) into electrical energy. These stations are the main source of electricity for the power grid.
Electrical grid – It is a geographically distributed system to connect source and users of electric power.
Electrical grounding – It is a conducting connection which links an electric circuit or equipment to the earth or a large conducting body, serving to protect individuals and equipment from high voltages and shock hazards by providing a low-resistance pathway for electrical current.
Electrical heat pump – It is a highly efficient HVAC (heating, ventilation, and air conditioning) device which uses electricity and a refrigerant cycle to transfer thermal energy rather than generating heat through combustion. It provides year-round climate control by pulling heat indoors during the winter and reversing the process to act as an air conditioner in the summer.
Electrical heat tracing – It is a system which uses specialized electric cables installed along pipes, tanks, or vessels to generate heat. It compensates for heat loss, protects pipes from freezing, and maintains specific process temperatures for fluids which need thermal management.
Electrical impedance – It is that property of a circuit which hat resists the passage of electric current, normally in the context of alternating current.
Electrical injection – It is the process of deliberately forcing an electrical current or voltage into a system. It is the process by which electrical current is used to introduce charge carriers into a semi-conductor laser, facilitating lasing action and enabling compact applications, particularly in nano-wire-based lasers.
Electrical input – It consists of an electrical energy, voltage, or current supplied to a system to perform a function. It can also refer to physical or digital signals (like sensor data or switch commands) which a device receives to process and produce a desired output.
Electrical installation – It is an assembly of interconnected electrical components, cables, and safety devices which distribute electricity safely throughout a structure. It encompasses everything from the main power source and distribution panel to final outlets and lighting, all designed to meet functional and safety standards.
Electrical insulation – It is a material which resists electrical current flow.
Electrical insulation paper – It is a grade of paper which is used for insulation of transformers, electrical machines, capacitors, and some cables.
Electrical insulator – It is a material in which electric current does not flow freely. The atoms of the insulator have tightly bound electrons which cannot readily move. The property which distinguishes an insulator is its resistivity. Insulators have higher resistivity than semi-conductors or conductors. The most common examples are non-metals.
Electrical interconnects – These are the physical pathways, such as cables, connectors, and printed circuit board (PCB), which transmit electrical signals and power between different components, devices, or sub-systems. They act as the ‘nervous system’ and ‘power grid’ of electronics, ensuring that systems function and communicate together efficiently.
Electrical isolation – It is the separation of two conductive materials from electrical contact. Galvanized steel is sometimes electrically isolated in order to prevent rapid consumption of the zinc coating.
Electrical layer – It is a component within a multi-layered structure, such as an electronic optical circuit board (EOCB), which is designed to facilitate electrical connections and signals among different layers, typically achieved through the use of electrical vias (small copper-plated holes) and specific material properties.
Electrical load – it is a consumer of electrical energy, turning it into light, heat, mechanical power, data, or chemical changes.
Electrically activated pressure sintering – It is frequently referred to as ‘electric current activated / assisted sintering’ (ECAS), ‘spark plasma sintering’ (SPS), or ‘field assisted sintering technique’ (FAST). It is an advanced powder metallurgy consolidation method. It is a process where simultaneous mechanical pressure and high-intensity, low-voltage electric current are applied to a powder or green compact, frequently under vacuum or protective atmosphere, to produce dense, solid materials.
Electrically conductive adhesive – It is a specialized glue used in electronics to bond parts together while allowing an electrical current to pass between them. It is composed of a non-conductive polymer base (like epoxy) mixed with highly conductive metallic fillers (such as silver or copper).
Electrical machine – It is a general term for machines using electro-magnetic forces, such as electric motors, electric generators, and others. They are electromechanical energy converters, e.g., an electric motor converts electricity to mechanical power while an electric generator converts mechanical power to electricity. The moving parts in a machine can be rotating (rotating machines) or linear (linear machines).
Electrical measurement – It is the process of quantifying physical electrical properties, such as voltage, current, resistance, and power, by comparing an unknown value to a predefined standard. It is a fundamental branch of metrology used to evaluate, control, and ensure the safety of electrical systems.
Electrical meter – It is a device that continuously measures and records the amount of electrical energy consumed by a residence, business, or piece of equipment. It integrates power over time and is typically calibrated in kilowatt-hours (kWh) for billing, monitoring, and efficiency analysis. An energy meter functions on the principle of measuring both instantaneous voltage and current, then integrating them over time to determine total energy. Energy meters measure and communicate information about electricity usage, typically for monitoring and billing by utilities. They can be classified into types such as smart meters, which provide remote reporting, and operate under either one-way or two-way communication systems.
Electrical mobility – It is a fundamental property defined as the ability of a charged particle (such as an electron, ion, or hole) to move through a medium in response to an applied electric field. It measures how fast a particle drifts per unit of electric field strength. In electronics and materials science, electrical mobility determines how easily charge carriers (electrons or holes) travel through a semiconductor or conductor. In the context of the automotive and power sectors, electrical mobility (frequently called e-mobility) refers to the use of electrified vehicles and powertrains for transportation.
Electrical network – It is a network of electrical components and conductors.
Electrical noise – It is also known as electronic noise. It refers to an unwanted, random fluctuations or disturbances in an electrical signal. It basically behaves as corrupting ‘background static’ which obscures the useful information in a circuit, which can cause device malfunctions, data transmission errors, or erratic readings.
Electrical percolation threshold – It is the critical concentration of a conductive material (filler) dispersed within an insulating material (matrix) at which the material suddenly transitions from an electrical insulator to an electrical conductor.
Electrical permittivity – It is the material property that directly relates the voltage and geometry of the system to the electrical field energy. Magnetic permeability is the magnetic field energy counterpart.
Electrical pin – It is a small, conductive metal terminal (or contact) designed to connect two electronic components or cables. It serves as a bridge for electrical current or data transfer, mating with a corresponding receptacle, socket, or printed circuit board (PCB) pad to complete an electrical circuit.
Electrical pitting – It is the formation of surface cavities by removal of metal as a result of an electrical discharge across an interface.
Electrical plant – It refers to an installation, equipment, or apparatus used to generate, transmit, or distribute electricity. In a broad sense, it can mean the massive industrial facilities which produce power, or collectively, the entire physical electrical system, like machinery, wiring, and generators, within a building or utility network.
Electrical polarity – It is the identification of electrical terminals where current is flowing in the same direction relative to the device.
Electrical position – It normally refers to a job in the field of electrical engineering or trades. Depending on the context, it can also refer to electrical orientation or a specific physical state of an electrically controlled switch or valve.
Electrical potential gradient – It is the rate at which electric potential (voltage) changes with respect to distance in a specific direction. It acts as a spatial ‘slope’ which determines how fast the voltage varies across a given space.
Electric power – It is the rate at which electrical energy is transferred or converted into other forms of energy in an electrical circuit. It measures how quickly work is done, dictating how much energy an electrical device consumes over a specific span of time.
Electrical power delivery – It is the process of transferring electrical energy from its source to a point of consumption. It broadly spans utility-scale electrical grids, moving generated electricity through transmission and distribution networks to homes and organizations, as well as consumer electronics, where it refers to high-speed charging protocols like USB (universal serial bus) power delivery (USB PD).
Electrical power industry – It is the sector involved in the generation, transmission, distribution, and sale of electrical energy to end-users. It forms the backbone of modern infrastructure, delivering power from sources like fossil fuels and renewables to homes and organizations. The sector operates through an interconnected network and is typically categorized into four core processes namely generation, transmission, distribution and retailing.
Electrical power production – It is also called electricity generation. It is the industrial process of transforming primary energy sources (like coal, natural gas, nuclear, solar, or wind) into usable electrical energy. This power is generated at power plants and is the important first step before transmission and distribution to consumers.
Electrical power system – It is an interconnected network designed to generate, transmit, distribute, and consume electrical energy. It converts different forms of raw energy (like thermal, nuclear, solar, or wind) into electricity and delivers it safely to residential, commercial, and industrial end-users. The field of power systems engineering encompasses the design, operation, and maintenance of these massive infrastructures, which are collectively known as the ‘electrical grid’. The entire system is typically divided into four primary stages: namely generation, transmission, sub-transmission, and distribution.
Electrical precipitator – It is air pollution control device which use electrodes in stack emissions emitting high voltage. Particles 0.1 micrometers and smaller can be attached and collected at discharge electrode.
Electrical properties of semiconductors – These properties refer to their ability to conduct electricity, falling between conductors and insulators, which can be precisely controlled through temperature, light, or structural doping. These properties determine how microchips and electronic devices process power and signals.
Electrical quantity – It is a measurable, physical property used to define, quantify, or analyze the behaviour of an electrical or electronic circuit. The most fundamental electrical quantity is electric charge (measured in Coulombs), which dictates the quantity of electricity.
Electrical resistance alloys – These alloys include those types used in instruments and control equipment, heating elements, and devices which convert heat generated to mechanical energy. They are classified as resistance alloys, heating alloys, and thermostat metals. The primary requirements for resistance alloys are uniform resistivity, stable resistance (no time-dependent aging effects), reproducible temperature coefficient of resistance, and low thermoelectric potential against copper. Properties of secondary importance are coefficient of expansion, mechanical strength, ductility, corrosion resistance, and ability to be joined to other metals by soldering, brazing, or welding. The heating alloys are mainly used for heating elements where the main requirements are high melting point, high electrical resistivity, reproductible temperature coefficient of resistance, good oxidation resistance, absence of volatile components, and resistance of contamination. Other desirable properties are good high-temperature creep strength, high emissivity, low thermal expansion, and low modulus (both of which help minimize thermal fatigue), good resistance to thermal shock, and good strength and ductility at fabrication temperatures. Thermostat metal is a composite material (normally in the form of sheet or strip) which consists of two or more materials bonded together, of which one can be a non-metal. Since the materials bonded together to form the composite differ in thermal expansion, the curvature of the composite is altered by changes in temperature. This is the fundamental characteristics of a thermostat metal. Thermostat metal is hence a complete, self-contained transducing system capable of transforming heat directly into mechanical energy for control, indicating, or monitoring purposes.
Electrical resistance element – It is a physical component designed to oppose the flow of electric current. These elements serve two main functions namely restricting current flow to control circuit logic or dissipating electrical energy into controlled heat.
Electrical resistance (ER) probe – It is an intrusive, real-time sensor used to measure metal loss caused by corrosion or erosion. It works on the principle that electrical resistance increases as a metal’s cross-sectional area decreases because of the material thinning.
Electrical-resistance strain gauge – It is a sensor which measures the deformation (strain) of an object by converting mechanical force into a change in electrical resistance. It consists of a thin, flexible metallic foil or wire arranged in a zigzag pattern, which increases in resistance when stretched and decreases when compressed, proportional to the deformation. It is a sensor used to measure mechanical deformation (strain) on an object. It converts microscopic changes in length into proportional electrical signals by measuring variations in its electrical resistance when stretched or compressed.
Electrical resistivity – It is the electrical resistance offered by a material of unit length and unit cross-sectional area or unit weight to the flow of current. It is the reciprocal of the conductivity. The value of 1⁄58 ohm-mm2/m (ohm square millimeter/metre) at 20 deg C is the resistivity equivalent to the International Annealed Copper Standard (IACS) for 100 % conductivity. This means that a wire of 100% conductivity, 1 meter in length and 1 square millimeter in cross-sectional area has a resistance of 0.017241 ohms at 20 deg C.
Electrical safety – It consists of the needed process to avoid electrical incidents through correct use of electrical equipment.
Electrical separation – It is also known as electrical isolation or galvanic isolation. It is a protective technique which separates electrical circuits. It prevents the direct flow of current between parts of a system while allowing signals or power to transfer safely, normally through transformers, optical isolators, or capacitors.
Electrical set-point, electric arc furnace – It consists of transformer tap, reactor tap, and impedance set-points.
Electrical signal – It is a form of information transmission which is typically represented by voltage or current. It changes over time and can be used for storing, transmitting, and exchanging information. In the context of fault diagnosis of mechanical equipment, electrical signals are particularly important.
Electrical spectrum – It refers to the representation of the power levels of different frequency components of electrical signals, such as pilot tones, in a given system. It can illustrate the presence of ghost tones generated by effects like cross-gain modulation (XGM) and stimulated Raman scattering (SRS) in optical networks.
Electrical spectrum analyzer – It is a test instrument which measures the magnitude (power / amplitude) of an electrical signal plotted against its frequency. While an oscilloscope displays signals over time, a spectrum analyzer breaks down complex signals into individual frequencies to reveal harmonics, noise, and distortion.
Electrical steel – It is a kind of special steel which is tailored to show certain specific magnetic properties such as small hysteresis area resulting in low energy dissipation per cycle, low power loss per cycle, low core loss, and high permeability. It is also called lamination steel, silicon steel, silicon-electrical steel, or transformer steel. The steel contains specific percentage of silicon in it which is responsible for its unique property. The exact formulation is tailored to produce specific magnetic properties. It is a speciality steel which is used in the cores of electromagnetic devices such as motors, generators, and transformers since it reduces power loss. Electrical steel has special physical properties which make it suitable for application in the production of electric equipments and appliances with rotating magnetic fields. Electrical steel is normally produced in cold-rolled strips of less than 2-millimeter thickness. Types of electrical steel are either non oriented electrical steel or grain oriented electrical steel.
Electrical strip – It is also called power strip. It is a device which expands a single wall outlet into multiple sockets, allowing several appliances or electronic devices to be plugged into one power source. It connects through a single extension cord and can include surge protection, switches, and USB (universal serial bus) ports.
Electrical substation – It is a facility connecting a distribution network to a transmission network, normally with one or more transformers.
Electrical supply – It refers to the delivery of electrical power from a utility grid to a facility, or an internal device which steps down and converts raw electrical energy into a safe, usable form for specific equipment. It is broken down into three main categories.
Electrical system – It is an integrated network of electrical components designed to generate, transmit, distribute, and utilize electrical power safely. It serves as the physical pathway which delivers usable energy from a source, such as a power grid or battery, to end-user devices, machines, or appliances.
Electrical technology – It is the practical application of electrical engineering and scientific principles. It encompasses the design, development, installation, operation, and maintenance of the systems, machines, and components used to generate, transmit, and utilize electrical power. While electrical engineering focuses heavily on the theoretical design of complex systems, electrical technology is hands-on and focuses on the practical implementation. It spans a wide range of applications, tools, and processes.
Electrical transducer – It is a device which converts one form of energy or signal into another, specifically into an electrical signal like voltage or current. It is essentially a sensor which detects a non-electrical physical quantity (like pressure, temperature, sound, etc.) and transforms it into a corresponding electrical signal. These signals can then be processed, measured, or used for control purposes.
Electrical valve – It is a motor-driven or electro-magnetic device which uses an electric actuator to automatically start, stop, or regulate the flow of fluids (liquids / gases) in response to signals from a control system. They are used in industrial automation for flow regulation, pressure control, and emergency shutdowns in sectors like HVAC (heating, ventilation, and air conditioning), water treatment, and chemical processing.
Electrical wiring – It is the installation of conductors, fixtures and protection devices for or an equipment.
Electrical work – It is the installation, maintenance, repair, or alteration of electrical systems, wiring, and equipment used for power, lighting, and communication. In physics, it refers to the energy transferred when an electric charge moves through a potential difference. The concept of electrical work is divided into two main contexts namely practical / trade where electrical work involves building, repairing, or troubleshooting physical electrical networks and physics / engineering where electrical work describes the quantity of energy needed to push an electric charge through a circuit against an electrical potential difference or voltage.
Electric arc – It is a continuous, luminous electrical discharge which occurs when a high current flows through a normally non-conductive medium, like air or gas. This creates a super-heated plasma channel between two electrodes, reaching temperatures up to 20,000 deg C. it is the discharge of electric current through an open space between conductors. It can be produced intentionally as a source of intense light and heat, or can be a result of an electrical fault.
Electric arc cutting – It is a thermal metal-severing process which uses the intense heat of an electric arc (frequently over 10,000 deg C) to melt and pierce through conductive metals. The arc is formed between an electrode and the work-piece, frequently using compressed gas to blow away molten metal.
Electric arc furnace (EAF) – An electric arc furnace is a furnace which heats material by means of an electric arc, combined with the action of chemical power provided by the use of oxygen and fuel. In electric arc furnaces, the charged material is directly exposed to an electric arc, and current from the furnace electrodes passes through the charged material. Arc furnaces differ from induction furnaces, in which the charge is instead heated by eddy currents. Electric arc furnace can be either a direct current furnace or an alternating current furnace. Industrial arc furnaces range in size from small units of approximately one-ton capacity up to about 400-ton unit. The furnace is used for the melting and refining of steel products and are a well-known source of flicker. The most prevalent use of this furnace is in the recycling of scrap steel. However, electric arc furnaces are also used in the production of high-grade alloy steel, aluminium, copper, lead and other metals.
Electric arc furnace dust – It is a hazardous by-product generated during the recycling of scrap steel in electric arc furnaces. It consists of fine, particulate matter captured by pollution control systems, which is rich in iron and zinc but also contains toxic heavy metals.
Electric arc furnace expert system – It is an integrated process control supervisor. It automatically recognizes deviations from the expected behaviour and re-tunes the melting program, acting on the electric power planning, on the chemical package, on the slag and steel metallurgy. Equipment constraints are integrated into the control. The expert system acts as a process supervisor which integrates basic automation and technological functions to enable the steel production in an effective and safe way, supporting each operation from the charging phase up to the tapping procedure.
Electric arc furnace process – It is a steelmaking process that uses high-power electric currents to melt and refine recycled scrap metal. Unlike traditional blast furnaces that rely on iron ore and coal, electric arc furnace process uses steel scrap, electricity and chemical energy to produce new, high-quality steel, making the process highly sustainable and energy-efficient.
Electric arc furnace slag – It is a stony, non-metallic by-product generated during the production of steel from recycled scrap metal. It forms when impurities like silica and phosphorus are oxidized and combined with fluxes like lime, creating a liquid layer which floats on top of the molten steel.
Electric arc spraying – It is a thermal spraying process using an arc between two consumable electrodes of surfacing materials as a heat source and a compressed gas to atomize and propel the surfacing material to the substrate.
Electric arc welding – It is a process which joins metal parts by using an electric current to create an electric arc. This arc generates intense heat (up to 6,000 deg C), which melts the base metals at the joint to form a fused, permanent bond as the metal cools.
Electric bonding – It is a term for surfacing by thermal spraying which consists of a group of processes in which finely divided metallic or non-metallic surfacing materials are deposited in a molten or semi-molten condition on a substrate to form a spray deposit. The surfacing material can be in the form of powder, rod, or wire.
Electric brazing – It is a brazing process in which the heat needed is obtained from the resistance to electric current flow in a circuit of which the work-piece is a part. It is also a brazing process which uses an arc to provide the heat.
Electric cable – It is an assembly of one or more electrical conductors bundled together within protective insulation and outer sheaths. It is designed to safely transmit electrical power or data / signals from a source to a receiver, preventing short circuits, electrical hazards, and environmental degradation.
Electric charge – It is a fundamental property of matter which causes subatomic particles to experience a force when placed in an electro-magnetic field. It is the foundation of all electrical and magnetic phenomena. It is the physical property of matter which causes it to experience a force when placed in an electro-magnetic field.
Electric chiller – It is a mechanical cooling system which converts electrical energy into cooling power by driving a compressor through a vapour-compression refrigeration cycle. It extracts heat from a fluid (like water or glycol), which is then circulated to cool industrial equipment or provide building air conditioning.
Electric circuit – It is a continuous, closed path which allows electric current (the flow of electrons) to travel from a power source to a device which uses it and back again.
Electric coefficient – It normally refers to any numerical constant used in electrical engineering to measure a specific material or device property, such as its response to an electric field, its conductivity, or its efficiency.
Electronic control – It is the management and influence over devices such as motors, lights, and appliances, utilizing sensors to monitor physical characteristics and convert them into electrical signals for regulation in different applications, including industrial processes.
Electric control system – It is a physical network of inter-connected electrical components which manage, direct, or regulate the behaviour of other devices. It acts as the ‘brain’ and ‘nervous system’ of machinery, taking in information, making decisions, and adjusting operations to achieve a desired output.
Electric current – It is the motion of electric charges.
Electric current activated / assisted sintering – It is a class of rapid consolidation techniques where mechanical pressure is combined with electric and thermal fields to densify powder materials. It uses high electric current densities, frequently pulsed direct current, to provide fast resistive (joule) heating, considerably shortening processing times compared to conventional methods.
Electric current perturbation – It is an electro-magnetic non-destructive evaluation method for detecting and characterizing defects in non-ferro-magnetic material. Laboratory evaluations have shown that this method can detect very small surface and subsurface cracks in both low-conductivity and high-conductivity metals (for example, titanium and aluminum alloys). Results from experiments and an analytical electric current perturbation model confirm that linear relationships exist between the electric current perturbation signal amplitude and the crack interfacial area and between the signal peak-to-peak separation and the crack length.
Electric delay line – It is an electronic component designed to intentionally introduce a precise, time-based delay to an electrical signal as it travels through a circuit. It is a fundamental building block used for maintaining signal synchronization, preventing data distortion, and phase matching in complex electronic systems. Delay lines are built to control the exact quantity of time (typically measured in nano-seconds or micro-seconds) it takes for a signal to travel from input to output.
Electric dipole – It is the result of a distribution of bound charges, i.e., separated charges which are bound to their centres of equilibrium by an elastic force Equal numbers of positive and negative charges are to be present in an uncharged medium.
Electric dipole moment – It is a quantity characteristic of a distribution of bound charges equal to the vector sum over the charges of the product of the charge and the position vector of the charge.
Electric dipole transition – It is a transition of an atom, molecule, or nucleus from one energy state to another, which results from the interaction of electro-magnetic radiation with the dipole moment of the molecule, atom, or nucleus.
Electric discharge machining – It is a manufacturing process which enables the machining of all electrically conductive materials, regardless of their hardness, by utilizing the erosive effect of electrical discharges between a tool and work-piece electrode. This process is particularly suited for creating complex 3D geometries, such as dies and moulds.
Electric double layer – It is a structure which forms at the interface between a metal surface (electrode) and an electrolyte solution, characterized by a charged solid surface balancing its potential with a layer of oppositely charged ions in the liquid. It consists of a rigid, inner Stern layer of ions and an outer diffuse layer, important for controlling electro-chemical reactions like electro-plating, corrosion, and metal extraction.
Electric double-layer capacitors – These are frequently called super-capacitors or ultra-capacitors. These are high-capacity energy storage devices which store electricity physically rather than chemically, enabling rapid charging and high-power density. They operate by forming an electric double layer of ions at the interface between porous electrodes and an electrolyte. Unlike batteries, Electric double-layer capacitors (EDLCs) use physical adsorption (electro-sorption) of ions, where opposite ions form a single molecular layer on the surface of porous carbon electrodes.
Electric drive – It is the system in which the electric motor is located and makes it spin. It is also referred to as the motor drive. In general, the device which controls the motor is called a drive. Electric drives are used to control the speed of motor. Electric drive can control both voltage and frequency input to the motor. If only voltage input to the motor is controlled by drive, then speed of motor is controlled. If both voltage and frequency inputs are controlled by drive then torque of motor is controlled. Drives can do more than control speed. The drive can also run the motor clockwise, counter clockwise or at a certain torque.
Electric drivers – These drivers refer to electric motors used to power compression systems, which are preferred when electricity is readily available and competitively priced compared to natural gas, particularly because of their lower operational costs and reduced maintenance compared to natural gas engines.
Electric drive-train – It is the system of components which delivers power from an energy source to the wheels in electric vehicles. It replaces the traditional internal combustion engine with an electric motor, relying on power electronics and a battery to propel the vehicle efficiently. The electric drive-train consists of three main, interconnected subsystems namely the energy source, the electric propulsion system, and the transmission.
Electric drive system – It is an electro-mechanical setup which converts electrical energy into mechanical energy to drive machinery and regulate motion. It precisely controls a motor’s speed, torque, and direction, functioning as the important bridge between a power source and a mechanical load.
Electric energy – It is the form of energy which is transferred between components, sub-systems, and systems through conduction along electrical conductors or by radiation in free space, such as in radio or TV (television) broadcasting.
Electric energy consumption – It is energy consumption in the form of electrical energy. It is the energy consumed as electricity. It is the total quantity of electrical energy utilized by a device, circuit, or system over a specific period. It is distinct from electrical power, which is the rate of energy transfer. While power is measured in watts or kilowatts, energy consumption is typically measured in watt-hours or kilowatt-hours. The relationship is fundamental i.e., energy equals power multiplied by time.
Electrical energy storage – It is the process of capturing electrical energy from a power grid or generator, converting it into a storable form, and discharging it back as electricity when needed. It is an important engineering mechanism for balancing energy supply with demand and stabilizing electrical networks.
Electric field – It is a vector field which exerts a force on electric charges.
Electric field effect – It is a shift in the energy of spectral lines because of an electrical field which is either externally applied or is an internal field caused by the presence of neighboring ions or atoms in a gas, solid, or liquid. It is also known as the Stark effect.
Electric field gradient – It is the rate of change of electric field with respect to distance.
Electric field strength – It is the force acting on a particle with unit electric charge, represented mathematically as ‘E = F/Q’, where ‘F’ is the force and ‘Q’ is the charge. It is measured in volts per meter and can be described as the gradient of a scalar function called potential.
Electric filter – It is a signal-processing circuit designed to pass specific frequencies while blocking, attenuating, or rejecting others. It reshapes electrical signals by modifying their amplitude and phase, enabling noise reduction, bandwidth management, and clear signal transmission across different applications.
Electric furnace – It is used for industrial process heating. It uses electricity for heating in place of a fuel. It can use resistance or induction heating. It is a metal melting, holding, or heating furnace which produces heat from electricity. It can operate on the resistance or induction principle.
Electric furnace process – It is an industrial engineering method which uses electricity as the main heat source to melt and refine materials like scrap steel. It relies on high-power electric arcs or electro-magnetic induction to generate temperatures up to 4,000 deg C, allowing for precise atmospheric control and high-quality alloy production.
Electric fusion welded pipe – It is a type of steel pipe manufactured by forming flat steel plates or coils into a cylindrical shape and welding the joint using an electric arc process, frequently with filler metal. It is characterized by high strength, durability, and a longitudinally welded seam, normally used in large-diameter applications.
Electric fusion welding – It is a welding process which uses an electric arc to melt the base metal and filler material (if used) to create a strong, permanent joint. It is a type of fusion welding, where materials are joined by melting them together. Electric fusion welding is normally used in the fabrication of pipes, particularly large-diameter pipes for pipelines.
Electric generator – It is a machine which converts mechanical energy to electrical energy by moving conductors through magnetic fields.
Electric glass – It is a family of glasses with a calcium alumino-boro-silicate composition and a maximum alkali content of 2 %. It contains a general-purpose fibre which is most frequently used in reinforced plastics, and is suitable for electrical laminates because of its high resistivity. It is also called E glass.
Electric hazard – A dangerous condition such that contact or equipment failure can result in electric shock, arc flash burn, thermal burn, or blast.
Electric heat pump – It is a mechanical device which utilizes a small quantity of electrical work to extract and upgrade ambient thermal energy from a low-temperature source (like air, ground, or water) and transfer it to a higher-temperature heat sink for space or water heating.
Electric hoists – These are normally used in the production shops for the raising, lowering and transporting material throughout the shop and positioning components in process or assembly operations. Electric hoist is powered by electrically driven motor. It is easy to operate and offer more flexibility. It is frequently specified when the application calls for more frequent and faster lifting, such as on a production line. An electric hoist with a motorized trolley is ideal for repetitive lifts which are required to travel long distances. Electric hoists can be a chain hoist or a wire rope hoist.
Electrician – An electrician is a skilled tradesperson who specializes in installing, maintaining, and repairing electrical wiring, systems, and equipment. Electricians ensure electrical systems operate safely and efficiently, frequently working with lighting, power, and control systems.
Electric inductor – It is a passive two-terminal electrical component which stores energy in a magnetic field when electric current flows through it. Also known as a coil, choke, or reactor, it normally consists of an insulated wire wound around a central core (like air, iron, or ferrite).
Electric industry – It refers to the sector involved in the generation, transmission, distribution, and sale of electrical power, including the development of technologies for energy storage systems such as vanadium redox batteries (VRB), which are used for peak regulation in power generation systems.
Electric input power – It is the rate at which electrical energy is supplied to a device or system to perform work. Measured in watts, it represents the total electrical power consumed from the source.
Electricity – It is the set of physical phenomena associated with electric charges.
Electricity grid – It is an interconnected network which delivers electricity from producers to consumers. It functions as a single massive system connecting power plants, substations, and transmission lines to move energy from where it is generated to homes, organizations, industries and essential services.
Electricity industry – It is the sector involved in the generation, transmission, distribution, and sale of electrical power to the public, industries, and organization. It functions as the critical infrastructure which converts primary energy sources into the usable electricity which powers modern economies.
Electricity market – It is a system enabling the exchange and trading of electrical energy. It manages the generation, transmission, distribution, and pricing of electricity from producers to end-users. These markets balance supply and demand in real-time and facilitate competition to determine pricing.https://energypedia.info/wiki/Electricity_Market_Design Electricity markets are broadly broken down into two main tiers (wholesale market and retail market), along with regional variations in structure.
Electricity meter – it is an instrument for the measurement of the electrical energy consumed at the user end.
Electricity network – It is defined as a complex system comprising generation, transmission, and distribution components which deliver power from generators to consumers through a network of high and low voltage systems, ensuring the balance between supply and demand to maintain electrical frequency.
Electricity production – It is the process of generating electrical energy from primary energy sources. It works by transforming other forms of energy, such as mechanical, heat, or solar energy, into electricity.
Electricity resource – It is a primary natural source or system used to generate electrical power. Since electricity is a secondary energy source, it is produced by converting raw resources (like coal or sunlight) into an electrical charge. These resources fall into two main categories: namely (i) renewable resources and (ii) non-renewable resources.
Electricity supply system – It is the complete, interconnected network which delivers electrical energy from its source to end-users. It encompasses the entire infrastructure needed to generate, transmit, and distribute electricity, including power plants, high-voltage lines, and local transformers.
Electricity transmission – It is the process of moving large quantities of electricity from power plants to substations near populated areas, where it is then distributed to consumers. It involves conveying electrical power efficiently and reliably over long distances using high-voltage transmission lines, frequently supported by towers or buried underground.
Electricity transmission and distribution grid – It is the interconnected network which delivers electrical energy from power plants to end-users. Transmission lines transport bulk, high-voltage power over long distances, while distribution lines step down the voltage and deliver it locally to final consumers. The transmission and distribution network connects the generation source to the final consumer and is divided into two distinct, interconnected stages namely (i) transmission grid, and (ii) distribution grid.
Electrical lines – These are conductors, wires or cables, which transfer electrical power from generators to users over long distances. Part of the electrical grid, these lines are categorized into high-voltage transmission lines on towers and lower-voltage distribution lines, which can be installed overhead on poles or underground as underground cables. Types of electrical lines are transmission lines which transport high-voltage electricity over long distances, and distribution lines which carry lower-voltage electricity from substations to neighbourhoods.
Electric lines engineering – It focuses on the design, construction, and maintenance of infrastructure used to transmit and distribute electrical power over long distances. It balances electrical efficiency with structural safety to ensure stable power delivery. The field is generally divided into two main categories namely overhead lines: and underground cables.
Electric load – It is a component or equipment in a circuit which consumes electrical energy and converts it into another form of energy (such as light, heat, or motion). It represents the power demand placed on a generation, transmission, or distribution system.
Electric load forecasting – It is the process of estimating future electricity demand over a given timeframe. It is a fundamental engineering mechanism used by power grid operators to ensure generation constantly matches consumption, minimize system operational costs, prevent grid failures, and optimize transmission capacities.
Electric load loss – It refers to the power dissipated as heat because of the current flowing through the resistive components of equipment (like windings in transformers or cables). It varies proportionally with the square of the applied load current, peaking during maximum demand. In heavy electrical equipment, load loss (frequently called copper loss) it represents the active power lost when current flows through the device’s coils. In electrical grids, load loss refers to the total energy lost in transmission lines, cables, and transformers as power is delivered from the source to the consumer. In power systems engineering, the term ‘loss of load’ takes on a probabilistic meaning related to grid reliability.
Electric logging – It is a downhole surveying technique which measures and records the electrical properties of sub-surface rock formations and their contained fluids. Lowered into a borehole using a probe called a ‘sonde’, it mainly assesses electrical resistivity and spontaneous potential to map geological structures and identify hydrocarbon or water zones.
Electric losses – It refer to the dissipation or reduction of electrical energy as it is generated, transmitted, or utilized. This lost energy is mainly converted into unwanted, unusable forms like heat (because of the resistance) or lost through electro-magnetic radiation and magnetic inefficiencies.
Electric machines – These are the devices which include power generators and electric motors, which convert mechanical energy into electrical energy and vice versa through the interaction of a rotor and a stator in a rotating magnetic field. Their performance is optimized by utilizing advanced soft magnetic materials and specific magnetic properties such as high magnetization and low coercivity.
Electric mobility – It refers to the use of electric-powered technologies in the transport sector, which has transitioned from niche applications to a central strategy aimed at addressing global heating challenges. It encompasses a shift from traditional internal combustion engine systems to electric vehicles, facilitated by innovations such as rechargeable batteries.
Electric motor – It is an electro-mechanical energy conversion device which convert electrical energy to mechanical energy through the action of a magnetic field. It is a machine which produces mechanical energy from electrical energy.
Electric motor-driven pump – It is a mechanical device which utilizes an electric motor to power a hydraulic pumping mechanism, converting electrical energy into mechanical energy to move fluids. These pumps are widely used across different sectors for continuous, controlled fluid transfer and pressure management.
Electric motor’s power rating – It specifies the maximum continuous mechanical power it can safely output at its shaft without overheating or suffering damage, while operating under manufacturer-specified conditions like voltage and ambient temperature. It is typically expressed in horsepower (hp) or kilowatts (kW).
Electric motor propulsion system – It is a setup which converts electrical energy into mechanical power to move a vehicle, vessel, or mechanism. It uses an electric motor as the prime mover and normally includes a power source (like a battery or generator), motor controllers, and inverters.
Electric motor pump – It is a device which converts electrical energy into mechanical energy to move, pressurize, or circulate fluids (liquids or gases). It combines an electric motor and a hydraulic pump into a single integrated unit, utilizing rotational force to drive impellers or pistons.
Electric network analysis – It is the process of mathematically calculating the unknown electrical parameters (such as voltage, current, and power) of inter-connected components within an electric circuit. It helps engineers design, simulate, and troubleshoot circuits which are too complex to solve with simple series or parallel reduction techniques.
Electric overhead travelling (EOT) cranes – These are electrically powered material handling machines which run on elevated fixed rails. They consist of a bridge spanning a workspace, a trolley, and a hoist to lift and move heavy loads along longitudinal, lateral, and vertical axes, normally found in metallurgy, steel mills, and heavy manufacturing.
Electric potential – It is a measure of the work required to move a unit electric charge in an electric field.
Electric power – It is the rate of transfer of electrical energy past a given point within a circuit. Its unit is the watt, the general unit of power, which is defined as one joule per second. Standard prefixes apply to watts are thousands, millions and billions of watts are called kilowatts, megawatts and gigawatts respectively. Electric power is normally produced by electric generators, but can also be supplied by sources such as electric batteries.
Electric power distribution – It is the final stage in the delivery of electricity. Electricity is carried from the transmission system to individual consumers.
Electric power industry – It is the sector responsible for the generation, transmission, distribution, and sale of electrical energy to the public and industries. It represents the practical application of electro-magnetism and circuit theory to harness, control, and deliver electrical power safely and efficiently.
Electric power transmission – It is a process by which the electric power is transported over long distances for eventual use by consumers. Electric power is transported over long distances at high voltages, which minimizes the loss of electricity. It is sent from generating power plants to the end consumer by transmission lines. Electricity by nature is difficult to store, hence the supply is to equal the demand at any given instant.
Electric resistance – It is the measure of a material’s opposition to the flow of electric current. It’s like the friction a wire experiences when electrons try to move through it. The unit of resistance is the ‘ohm’.
Electric resistance welding – It joins metal pieces by passing an electric current through them, creating heat because of the resistance of the material at the interface. This heat melts the metal, and pressure is applied to solidify the joint, creating a weld. Electric resistance welding is a type of pressure welding which does not use filler material.
Electric resistance welded pipes and tubes – These pipes and tubes are manufactured by rolling metal and then welding it longitudinally across its length. Electric resistance welded (ERW) pipes have a welded joint in their cross-section. It is manufactured from strip / coil and can be manufactured up to 600 millimeters outer diameter.
Electric shock – It is an injury caused to people by electric current.
Electric spark – It is a sudden, short-lived flash of light and electrical discharge which occurs when a high electric field causes a normally insulating medium, like air, to become temporarily conductive. It essentially involves electricity jumping across a gap in a material which normally does not conduct electricity. It is an abrupt electrical discharge which occurs when a sufficiently high electric field creates an ionized, electrically conductive channel through a normally-insulating medium, frequently air or other gases or gas mixtures. The rapid transition from a non-conducting to a conductive state produces a brief emission of light and a sharp crack or snapping sound. A spark is created when the applied electric field exceeds the dielectric breakdown strength of the intervening medium. For air, the breakdown strength is around 30 kilovolts per centimeter at sea level. Experimentally, this figure tends to differ depending upon humidity, atmospheric pressure, shape of electrodes (needle and ground-plane, hemispherical etc.) and the corresponding spacing between them and even the type of waveform, whether sinusoidal or cosine-rectangular.
Electric surveys – These surveys measure either the natural flow of electricity in the ground, or galvanic current led into the ground and accurately controlled. Electrical surveys are used to locate mineral deposits at shallow depth and map geological structures to determine the depth of overburden to bedrock, or to locate the groundwater table.
Electric switch – It is a fundamental, binary device which manages electrical flow by opening (breaking) or closing (making) a circuit. It acts as a safety and control mechanism, either stopping the current or allowing it to travel to a load (like a light or motor). Switches can be operated manually or automatically.
Electrical network topology – It is the arrangement and interconnection of components within an electrical circuit. By ignoring component values, it uses graph theory to map the relationships of nodes and branches, allowing engineers to analyze complex circuits using matrices and Kirchhoff’s laws.
Electric pathway – It is frequently called an electric circuit. It is a closed, continuous loop which allows electric current, a flow of electrons, to travel. It connects a power source to a device that uses the energy, enabling electricity to perform work safely and return to the source.
Electric polarization – It is the slight separation of positive and negative charges within an insulating material (dielectric) induced by an external electric field. It quantifies how the material responds to the field by creating or aligning microscopic electric dipoles.
Electric potential – It is the quantity of work rneeded to move a positive test charge from a reference point (typically infinity) to a specific point within an electric field, divided by the magnitude of the charge. It basically measures the potential energy per unit charge at any given location.
Electric power distribution – It is the final stage of the electrical grid, responsible for delivering electricity from transmission systems to end-users. It safely converts high-voltage electricity into lower, usable levels through a network of substations, transformers, and power lines.
Electric power factor correction – It is the process of maximizing the efficiency of an AC (alternating current) electrical system by minimizing the ‘reactive power’ which oscillates between the source and inductive loads (like motors and transformers). It brings the power factor as close to unity as possible.
Electric power industry – It encompasses the sector of the economy involved in the generation, transmission, distribution, and sale of electrical energy to the public and industry. It relies on a huge, inter-connected infrastructure to convert different energy sources into usable electricity and deliver it instantly to meet consumer demand.
Electric power input – It is the total electrical energy supplied to a device or system to operate it. It is measured in watts or kilowatts and represents the exact electricity drawn from the grid or power source.
Electric power quality – It is the degree to which the voltage, frequency, and waveform of a power supply conform to established standards. Ideally, electrical power is delivered as a steady, smooth sinusoidal wave at a constant voltage and frequency. Poor power quality causes equipment malfunctions, energy waste, and system downtime.
Electric power sector – It is the inter-connected system of infrastructure and organizations responsible for generating, transmitting, distributing, and selling electricity to end-users. It encompasses the entire supply chain from power plants to the electrical outlets in homes and organizations.
Electric power systems – These are real-time energy delivery systems which generate, transport, and supply electrical energy instantaneously, balancing generation and demand at all times. They consist of components including power plants, high-voltage transmission lines, substations, and distribution networks which facilitate the efficient delivery of electricity to end users.
Electric power system interconnection – It is the linkage of multiple electrical grids, power plants, and transmission lines into a single, synchronized network. This configuration allows regional grids to share power, balance supply and demand, and provide backup capacity during outages or surges in peak load.
Electric power system measurement – It is the process of quantifying state variables (such as voltage magnitude, phase angle, and current) and operational parameters to monitor, analyze, and control the electrical grid. It ensures system stability, optimal efficiency, and accurate billing.
Electric power system planning – It is the strategic process of designing and scheduling the development of electricity infrastructure, including generation, transmission, and distribution. Its goal is to guarantee a reliable, cost-effective, and sustainable power supply which meets future consumer demands.
Electric power transmission – It is the bulk movement of electrical energy from generating stations (like power plants) to electrical substations. It is the critical middle step in the electrical grid, moving high-voltage electricity over long distances before it is stepped down for local distribution to consumers.
Electric power transmission network – It is the interconnected grid system which transports bulk electrical energy from generating stations (power plants) to regional distribution substations. It forms the important high-voltage backbone of the electrical grid.
Electric power utilization – It refers to the process of using electric power by devices to produce desired outputs such as light, motion, and heat, while some energy is inevitably lost as waste heat. It is quantified by the rate of energy transfer, measured in watts, and involves the consumption of electric energy over time.
Electric propulsion – It is defined as a class of low thrust propulsion system which utilizes electric and magnetic fields to accelerate and expel charged ion particles at high speeds, allowing satellites to adjust their orbits and maintain position with lower thrust and propellant consumption compared to chemical propulsion systems.
Electric resistance heater – It is a device which converts electrical energy into heat by passing an electric current through a resistive material. It operates at 100 % conversion efficiency, directly translating all consumed electrical power into usable thermal energy based on Joule’s law.
Electric resistance welded – It is a process which permanently joins metals by passing a high-power electric current through the joint. It relies on the natural electrical resistance of the materials to generate intense heat, melting the joint so pressure can forge the pieces together without filler material. Electric resistance welded relies on a precise combination of electrical current, contact resistance, and mechanical pressure to fuse components.
Electric road vehicle – It is an automotive vehicle designed for public roads which utilizes one or more electric motors for propulsion, relying mainly on electrical energy rather than an internal combustion engine (ICE). In engineering and standardization, such as the International Organization for Standardization specifications ISO 6469/5474, electric road vehicles (ERVs) are defined strictly by how they generate and receive their power, manage energy, and interact with the road.
Electric scooter – It is a compact, plug-in, two-wheeled or three-wheeled personal mobility device which propels the rider using a battery-powered electric motor. It serves as a specialized mechatronic system, relying on the seamless integration of electrical power, mechanical propulsion, and digital control.
Electric stress – It refers to the magnitude of the electric field applied to an insulating material, expressed as the potential difference per unit thickness. It represents the electrical pressure or tension placed on a dielectric material, which can lead to material breakdown if it exceeds its designed tolerance.
Electric switch – It is a fundamental control component designed to selectively open and close an electric circuit. By separating or touching conducting contacts, a switch safely interrupts current or diverts it to a different path, allowing for precise power control and system protection. Electric switches form the mechanical and electronic foundation for power transmission, automation, and circuit management. They are classified according to several core engineering principles.
Electric tower – It is also called transmission tower. It is a tall, heavy-duty structure used to support high-voltage overhead power lines. These towers are important to the electrical grid, transporting bulk electrical power from generating stations to substations at voltages typically exceeding 45 kilo-volts.
Electric traction – It is a system where electric motors provide the driving force for locomotion, as seen in electric trains, trams, and other vehicles. It offers advantages over traditional systems like steam or diesel, including higher power-to-weight ratio, regenerative braking capabilities, and lower emissions.
Electric typewriter – It is an electro-mechanical writing device where an electric motor powers the heavy mechanical actions, like striking the typebar or rotating a type ball. By relying on electricity, the machine needs considerably less physical effort from the operator compared to manual typewriters. From an engineering perspective, electric typewriters have bridged the gap between purely mechanical tools and early digital word processors.
Electric upsetting – It is a very different process compared to split die machine upsetting, but can be used to produce similar forgings. Normally, it is used to gather a large volume of metal at the end or along the length of a bar which is subsequently forged to a finished shape in another operation. Upset forming of the work-piece results when intense electric current is passed through the work-piece between contacts called the vise and anvil. The resistance to current flow heats the bar between the contacts to the plastic state. Force is applied to the cold ends of the bar pushing it through the vise at a controlled rate of speed. The heated portion grows into a bulb-shaped section. As the volume in the bulb-shaped section increases, its resistance, relative to the volume, decreases, hence slowing the heating in that portion. The smaller portion of the work-piece between contacts has more resistance and continues to heat and enlarge. The anvil retracts slowly when the bulb grows to the desired diameter allowing room for an elongated shape to develop. Large upset ratios can be achieved, exceeding 4 (four) diameters, with superior grain flow characteristics when compared to other gathering methods. The upset part, using the same heat, can go directly to the forging operation. Normally, because of the high upset ratios possible, normally only one blow in the forging press or hammer is needed.
Electric utility – It is a corporate entity or public agency which generates, transmits, and distributes electric power for sale. It serves as the backbone of the electrical grid, responsible for balancing real-time power generation with consumer demand while maintaining strict voltage and frequency standards.
Electric utility sector – It is the foundational industry responsible for generating, transmitting, and distributing electricity to consumers. From an engineering perspective, it represents the physical infrastructure, the electrical grid, designed to instantly convert raw energy sources into usable power and safely route it across large distances to meet continuous, fluctuating demand.
Electric vehicle – It is a vehicle powered by one or more electric motors, using energy stored in rechargeable batteries rather than an internal combustion engine (ICE) fueled by gasoline or diesel. Electric vehicles (EVs) produce no direct exhaust emissions and are charged from external electricity sources, making them a cleaner and quieter transportation alternative.
Electric welding – It is a manufacturing process which joins two or more metal pieces together by using electrical energy to generate the intense heat needed to melt and fuse the materials. Once the molten metal cools, it forms a strong, continuous, and homogeneous joint. This process is normally categorized into several primary methods depending on how the electrical energy creates the heat.
Electric wireline – It also known as an e-line. It is a cabling technology used to lower sensors, perforating tools, and diagnostic instruments into a wellbore. The cable contains internal electrical conductors, enabling two-way communication to transmit real-time data and power between surface control units and downhole equipment.
Electrification – It is applying electric power to a process which has been previously done by other means, or, development of an electric power system in a region which previously had none.
Electro-active polymers – These are polymers which significantly changes size or shape when exposed to an electric field. Electro-active polymers (EAPs) are ‘smart’ polymers which dramatically change in size, shape, or volume in response to electrical stimulation. Electro-active polymers are normally divided into two main categories based on how the electrical energy transfer occurs. These types are electronic electro-active polymer, and ionic electro-active polymers.
Electrocatalyst – It is a specialized material which accelerates electro-chemical reactions at the electrode-electrolyte interface. It functions by adsorbing reactants, producing intermediates, and facilitating charge transfer to lower the activation energy required to drive a reaction.
Electro-catalytic activity – It defines how efficiently a catalyst accelerates an electro-chemical reaction at an electrode surface. Maximizing this metric involves lowering the reaction’s energy barrier (overpotential) to achieve faster reaction rates, higher energy conversion efficiency, and greater product selectivity in systems like fuel cells and water electrolyzers.
Electro-chemical admittance – It is the inverse of electro-chemical impedance.
Electro-chemical capacitor – It is widely known as a supercapacitor or ultracapacitor. It is an energy storage device bridging the gap between conventional electrostatic capacitors and chemical batteries. It delivers exceptionally high-power density and rapid charging capabilities by storing energy directly at the electrode-electrolyte interface.
Electro-chemical cell – It is an electrochemical system consisting of an anode and a cathode in metallic contact and immersed in an electrolyte. The anode and cathode can be different metals or dissimilar areas on the same metal surface.
Electro-chemical chloride extraction – It is a rehabilitation technique for reinforced concrete structures which removes corrosive chloride ions (such as salt) away from embedded steel. It works by applying a temporary, strong direct current between the steel reinforcement (which acts as the cathode) and a surface-mounted anode.
Electro-chemical compatibility – It is the ability of two or more materials, components, or systems to exist in intimate contact without causing or experiencing accelerated chemical degradation, corrosion, or performance failure because of the electro-chemical interactions.
Electro-chemical corrosion – It is the corrosion which is accompanied by a flow of electrons between cathodic and anodic areas on metallic surfaces.
Electro-chemical deposition – It is also known as electro-deposition or electro-plating. It is a material processing technique which uses an electrical current to reduce dissolved metal ions in an electrolyte solution, forming a thin, solid coating on an electrode. It is widely used to alter surface properties like wear resistance, corrosion, and conductivity.
Electro-chemical desalination – It is a water purification process which uses an applied electrical potential to drive the transport of dissolved salt ions Na+, Cl-) out of saline water. Unlike traditional high-pressure reverse osmosis, it directly targets charged particles using electricity, enabling low-energy separation, ion-selective removal, and targeted brackish water treatment.
Electro-chemical discharge machining – It is the metal removal by a combination of the processes of electro-chemical machining (ECM) and electrical discharge machining (EDM). Majority of the metal removal occurs through anodic dissolution (i.e., ECM action). Oxide films which form as a result of electrolytic action through an electrolytic fluid are removed by intermittent spark discharges (i.e., EDM action). Hence, the combination of the two actions.
Electro-chemical dissolution -it is a non-thermal material removal process where an anodic metal work-piece oxidizes and dissolves into an electrolyte solution as cations, driven by an applied electrical current. The reaction relies on Faraday’s Laws of Electrolysis, ensuring dissolution is highly predictable. This process is the fundamental mechanism behind highly precise manufacturing operations and surface treatments.
Electro-chemical double layer capacitor – It is normally known as a supercapacitor. It is an electrostatic energy storage device. It stores energy physically through the separation of charges at the interface between an electrode and an electrolyte, rather than through chemical reactions.
Electro-chemical effect – It is the interaction between electrical energy and chemical change, where electrical current drives a chemical reaction (electrolysis) or spontaneous chemical reactions generate electricity (batteries). These effects are quantified through thermodynamics, charge transfer, and mass transport at electrode-electrolyte interfaces.
Electro-chemical energy storage – It is the process of converting electrical energy into chemical energy to be stored, and converting it back into electrical energy on demand through reversible reduction-oxidation (redox) reactions. It is the foundation for technologies ranging from portable electronics to grid-scale power stabilization.
Electro-chemical engineering – It is that branch of engineering which deals with the application of electro-chemistry to practical issues.
Electro-chemical equivalent – It is the weight of an element or group of elements oxidized or reduced at 100 % efficiency by the passage of a unit quantity of electricity. It is normally expressed as grams per coulomb.
Electro-chemical etching – It is also called electrolytic etching. It is a non-mechanical, anodic dissolution process which uses direct current (DC) and an electrolyte to selectively remove material from a conductive surface. It works by connecting a metal work-piece as the anode, which dissolves at a controlled rate to create precise, stress-free marks, features, or microstructures.
Electro-chemical grinding – It is a process whereby metal is removed by deplating. The work-piece is the anode, while the cathode is a conductive aluminum oxide-copper or metal-bonded diamond grinding wheel with abrasive particles. Majority of the metal is removed by deplating, around 0.05 % to 10 % is removed by abrasive cutting.
Electro-chemical hydrogen storage – It is the process of storing hydrogen atoms within a host material (like porous carbon or metal alloys) through the electro-chemical decomposition of an aqueous electrolyte. Rather than needing extreme physical compression or cryogenic temperatures, it safely stores hydrogen ions as mobile charges at ambient conditions.
Electro-chemical impedance – It is the frequency-dependent complex-valued proportionality factor (dE/ di) between the applied potential or current and the response signal. This factor is the total opposition (omega or omega·centimeter-square) of an electro-chemical system to the passage of charge. The value is related to the corrosion rate under certain circumstances.
Electro-chemical kinetics – It is the study of the rates at which oxidation and reduction (redox) reactions occur at the interface of an electrode and an electrolyte. It bridges atomic-level electron transfer with macroscopic performance, driving the design of batteries, fuel cells, and industrial electrolysis systems.
Electro-chemical machining – It is the controlled metal removal by anodic dissolution. Direct current passes through flowing film of conductive solution which separates the work-piece from the electrode tool. The work-piece is the anode, and the tool is the cathode.
Electro-chemical metal corrosion – It is the deterioration of a metal because of a chemical reaction with its environment, specifically involving the flow of electrons between anodic and cathodic regions in the presence of an electrolyte. This process involves simultaneous oxidation (metal loss) at the anode and reduction (e.g., oxygen consumption) at the cathode.
Electro-chemical methods – These methods use electricity to drive or measure chemical reactions. They are important for material synthesis, energy storage, surface treatments, and chemical analysis. By controlling electrical parameters like current and potential, engineers can manipulate molecular and surface interactions for industrial production.
Electro-chemical micro-machining – It is also called micro-e Electro-chemical machining. It is a non-traditional, non-contact manufacturing process which removes conductive material atom-by-atom through anodic dissolution at micro-scales (5 micrometers to 50 micrometers. It uses a tool electrode (cathode) and a work-piece (anode) separated by a small electrolyte gap to produce high-precision, stress-free, and complex micro-geometries without tool wear.
Electro-chemical micro-system – It is an interdisciplinary technology which integrates principles of electro-chemistry with micro-engineering. It focuses on the miniaturization and scaled-down application of chemical reactions and electrical systems, creating highly integrated devices that sense, actuate, and control processes at the micrometer to millimeter scale.
Electro-chemical monitoring – It is an in-situ method which measures chemical species, corrosion rates, or physiological parameters by analyzing electrical signals, such as current, voltage, or impedance, generated by electron-transfer reactions. It provides real-time, continuous data without needing physical sampling.
Electro-chemical polishing – It is an attack-polishing method in which the chemical action of the polishing fluid is improved or controlled by the application of an electric current between the sample and the polishing wheel.
Electro-chemical potential – It is the partial derivative of the total electro-chemical free energy of a constituent with respect to the number of moles of this constituent where all factors are kept constant. It is analogous to the chemical potential of a constituent except that it includes the electric as well as chemical contributions to the free energy. It is the potential of an electrode in an electrolyte relative to a reference electrode measured under open circuit conditions.
Electro-chemical potentio-kinetic reactivation (EPR) test – It is a quantitative, non-destructive electro-chemical technique used to measure the degree of sensitization (DOS) in stainless steels and nickel-based alloys. It determines how susceptible a material is to intergranular corrosion (IGC) caused by chromium depletion at grain boundaries, which normally occurs during welding or heat treatment.
Electro-chemical process – It is a chemical reaction involving the transfer of electrons between a solid electrode and an ionically conducting electrolyte, converting chemical energy into electrical energy or vice versa. These redox reactions occur at the interface of electrodes and electrolytes, enabling applications like batteries, electrolysis, and metal refining.
Electro-chemical reaction – It is a reaction caused by passage of an electric current through a medium that contains mobile ions (as in electrolysis); or, a spontaneous reaction made to cause current to flow in a conductor external to this medium (as in a galvanic cell). In either event, electrical connection is made to the external portion of the circuit through a pair of electrodes.
Electro-chemical sensing – It is an analytical engineering process that converts chemical interactions into measurable electrical signals. It relies on a recognition layer that interacts with a target analyte, and an electrochemical transducer (electrodes) that measures the resulting change in voltage, current, or conductivity to determine the substance’s concentration.
Electro- chemical sensors – These are the devices developed to measure specific ions in solution, normally used for pH measurement and increasingly applied in environmental contexts to assess soil chemical properties. These are characterized by their durability, portability, fast response, and capability to operate in unfiltered soil slurries.
Electro-chemical series – It is the series of elements arranged as per their standard electrode potentials, with ‘noble’ metals such as gold being positive and ‘active’ metals such as zinc being negative. In corrosion studies, the analogous but more practical galvanic series of metals is normally used. The relative positions of a given metal are not necessarily the same in the two series.
Electro-chemical synthesis systems – These are frequently referred to as electrosynthesis. These are methods and apparatuses which use electrical energy to drive chemical reactions, resulting in the creation of new compounds or materials. These systems replace traditional chemical reagents (oxidants or reductants) with controlled electron transfer at an electrode surface, making them a sustainable and precise alternative for synthesis, frequently operating under milder conditions.
Electro-chemical systems – These are processes which use electrical energy to drive chemical reactions (reduction-oxidation or redox) to extract, refine, or modify metals. These systems involve the transfer of electrons between electrodes (anode and cathode) through an ionically conducting electrolyte, enabling the separation of metals from their ores or the purification of metals with high precision.
Electro-chemical techniques – These techniques refer to methods which utilize the relationship between electrical energy and chemical reactions to drive material processing, energy conversion, or analytical measurements. By applying electrical potential or current, these electrified technologies control oxidation-reduction (redox) reactions at the interface between an electrode and an electrolyte. These techniques span multiple engineering disciplines, mainly chemical, materials, and electrical engineering. These can be broadly broken down into two main categories namely industrial/processing engineering and analytical engineering.
Electro-chemical water treatment – It is a process which utilizes electric currents to drive chemical reactions, separate ions, or generate reactive species to remove pollutants from water. It acts as a highly efficient, chemical-free alternative to traditional water purification, offering a targeted approach to dismantling contaminants at the molecular level.
Electro-chemiluminescence – It is an analytical process where light is emitted from chemical reactions initiated at an electrode surface. Electrochemically generated species undergo high-energy electron-transfer reactions to form an excited state, which releases a photon (light) upon returning to its ground state.
Electro-chemistry – It is the branch of chemistry which studies the relationship between chemical changes and electricity, encompassing how chemical reactions produce electricity and how electrical energy drives chemical transformations. It focuses on processes involving electron transfer between electrodes (anode / cathode) and an electrolyte, important for batteries, corrosion, and plating.
Electro-chromic window – It is a smart glazing system which reversibly alters its optical properties (tint and transparency) in response to a low-voltage electrical stimulus. By actively controlling visible light and solar heat, it optimizes natural daylight, reduces glare, and considerably lowers building energy consumption.
Electro-chromism – It is a phenomenon where materials undergo persistent but reversible changes in colour, transmittance, or reflectance when an external electrical voltage is applied. This optical shift is driven by an electro-chemical redox reaction which alters the material’s electronic structure, frequently accompanied by the intercalation (insertion / extraction) of ions.
Electro-coagulation – It is an advanced, chemical-free wastewater treatment technology which destabilizes suspended, emulsified, or dissolved contaminants using an electrical current and sacrificial metal electrodes. It forces pollutants to agglomerate into larger, easily removable flocs through a combination of electro-chemistry, coagulation, and physical flotation.
Electro-conductive textiles – These are flexible fabrics embedded with conductive elements (like metals, carbon, or conductive polymers) which allow them to conduct electricity, transmit data, or generate heat. They are foundational for wearable electronics, and smart safety gear.
Electro-corrosive wear – It is the wear of a solid surface which is accelerated by the presence of a corrosion-inducing electrical potential across the contact interface. This process is normally associated with wear in the presence of a liquid electrolyte in the interface. However, moisture from the air can also facilitate this type of wear when a galvanic wear couple exists and the contacting materials are sufficiently reactive.
Electro-crystallization – It is a specialized electro-chemical process in metallurgy where metal ions dissolved in an electrolyte are reduced to metal atoms on an electrode surface, forming a solid metallic deposit. It is a critical component of electro-metallurgy, combining charge transfer with crystallization to create pure metals, functional coatings, or nanostructures.
Electrode – It is compressed graphite or carbon cylinder or rod used to conduct electric current in electric arc furnaces, arc lamps, and so forth. Anode and cathode are two types of electrodes. It also consists of one of a pair of conductors introduced into an electrochemical cell, between which the ions in the intervening medium flow in opposite directions and on whose surfaces, reactions occur (when appropriate external connection is made). In direct current operation, one electrode or ‘pole’ is positively charged, the other negatively.
Electrode array – It is a systematic, multi-dimensional configuration of individual electrodes used to measure or deliver electrical signals. By spacing multiple sensors close together, engineers can achieve highly localized spatial resolution, map complex electrical fields, or stimulate target areas with pinpoint precision.
Electrode assembly – It is a multi-layer system where the physical electrodes and active materials are combined into a single, functional unit. Most prominently known in electro-chemical engineering as a membrane electrode assembly (MEA), it acts as the ‘heart’ of fuel cells, electrolyzers, and batteries.]
Electrode cable – It is the electrical conductor between the source of arc welding current and the electrode holder.
Electrode cell – It refers to an electro-chemical system where electrical energy and chemical energy are interconverted. It consists of two or more electrodes immersed in an electrolyte. The electrodes serve as the points where current enters or leaves the cell, facilitating important reduction and oxidation (redox) reactions.
Electrode coating – It refers to the functional layer applied to a conductive substrate or core. Its definition and purpose depend strictly on the discipline. It broadly falls into two main categories namely energy storage (batteries/capacitors) and materials joining (arc welding).
Electrode contact – It is an interface which creates a firm electrical connection between a conductive element and a non-metallic medium. It facilitates the controlled transfer of electrons or ions, acting as the critical transition point where electrical current enters or leaves a circuit, or semi-conductor.
Electrode control system – It is the key control system for an electric arc furnace. It approaches towards an automated power control normally rely on evaluations of the arc current and voltage. It is a closed-loop electrode control system. The basic task is to control the position of the electrodes, more specific to maintain the electrical operating points.
Electrode deposition – It is the weight of weld-metal deposit obtained from a unit length of electrode.
Electrode extension – For gas metal arc welding, flux cored arc welding, and submerged arc welding, it is the length of unmelted electrode extending beyond the end of the contact tube.
Electrode force – It refers to the mechanical pressure applied by the welding electrodes to clamp work-pieces together, mainly in resistance welding (e.g., spot, seam, or projection welding). It establishes proper electrical contact resistance, ensuring uniform current flow and metallurgical fusion.
Electrode gap – It is the precise separation distance between two conductive electrodes. It dictates electrical resistance, voltage requirements for dielectric breakdown, and the efficiency of energy or current transfer between the conductors.
Electrode geometry – It refers to the physical size, shape, surface configuration, and spatial arrangement of an electrode. It dictates how electric fields and current densities are distributed, fundamentally controlling the efficiency, thermal performance, and reaction rates of electrical and electro-chemical systems.
Electrode holder – It is a device used for mechanically holding the electrode while conducting current to it.
Electrode indentation, resistance welding – It is the depression formed on the surface of work-pieces by electrodes.
Electrode lead – It is the electrical conductor between the source of arc welding current and the electrode holder.
Electrode life – It is the operational lifespan of a conductor used to establish electrical contact with a non-metallic part of a circuit. Depending on the discipline, it is defined either by the total number of continuous operational cycles (e.g., welds or pulses) or the duration of use before physical degradation impairs performance.
Electrode polarization – It is the change of electrode potential with respect to a reference value. The change can be caused, for example, by the application of an external electrical current or by the addition of an oxidant or reductant.
Electro-deposited coatings – It is frequently referred to as electro-plating, are metal coatings applied to a conductive substrate using an electro-chemical process. It is a metallurgical surface treatment technique where a direct current (DC) reduces dissolved metal cations in an electrolyte solution, causing them to deposit as a thin, coherent, and solid metal layer on an object.
Electro-deposition process – It is a manufacturing process which uses electric current to reduce dissolved metal ions in an electrolyte solution, causing them to deposit as a solid thin film onto a conductive substrate (cathode). It is mainly used to improve surface properties, including corrosion resistance, wear resistance, electrical conductivity, and aesthetic appearance. It is (i) the deposition of a conductive material from a plating solution by the application of electric current, and (ii) The deposition of a substance on an electrode by passing electric current through an electrolyte. Electro-chemical plating, electro-forming, electro-refining, and electro-winning result from electro-deposition.
Electro-deposition technique – It is an electro-chemical manufacturing technique which uses electrical current to reduce dissolved metal ions in an electrolyte solution, causing them to deposit as a solid, thin film onto a conductive substrate. It is widely utilized for protective coatings, electronics manufacturing, and creating free-standing metal objects.
Electrode potential – It is the potential of an electrode in electrolysis as measured against a reference electrode. The electrode potential does not include any resistance losses in potential in either the solution or external circuit. It represents the reversible work to move a unit charge from the electrode surface through the solution to the reference electrode. It is also the difference in potential between an electrode and the immediately adjacent electrolyte referred to some standard electrode potential as zero. Different types of electrode potentials are dynamic, equilibrium, static, and standard.
Electrode quality steel – It is made of steel grade having low carbon steel (less than 0.1 %), low sulphur and phosphorus contents, and low percentage of silicon (less than 0.1 %). Excess silicon in welding wire results in heavy sputtering and gassing in weld pool. The electrode quality steel also has only small quantities of aluminum and copper levels. These elements are to be kept very low since they can cause undesirable brittleness in the weld metal. Earlier electrode quality steels were of rimming quality steel when the steelmaking used to follow the ingot casting route.
Electrode reaction – It is the interfacial reaction equivalent to a transfer of charge between electronic and ionic conductors.
Electrode response – It defines how an electrode converts an electrical signal into a chemical reaction (or vice versa), and how faithfully it tracks changes in an environment. This behaviour dictates the sensitivity, speed, and accuracy of sensors, and energy systems.
Electrode size – It refers to the physical dimensions of the conductor used to transfer electrical current to or from a work-piece. Depending on the discipline, this measurement dictates the capacity, efficiency, and operational limits of the system.
Electrode structure – It refers to the physical, chemical, and architectural design of an electrical conductor used to make contact with a non-metallic part of a circuit, such as an electrolyte, or semi-conductor. It acts as important interface where electrons and ions interact to facilitate electrical or electro-chemical processes. Electrode structures can be understood across multiple scales, ranging from macroscopic dimensions down to microscopic architectural features.
Electrode surface – It is the boundary layer where an electrode interfaces with an adjacent medium (such as an electrolyte, or a gas). It serves as the physical site for electron transfer, electrical sensing, or chemical redox reactions.
Electrode tip – It refers to the terminal shape, angle, or material at the end of an electrical conductor. It is the specific point where electricity enters or leaves a medium, such as a welding arc, or a battery, to perform a highly concentrated action.
Electrode type – An electrode is an electrical conductor which interfaces with a nonmetallic part of a circuit (such as an electrolyte, or semi-conductor). It allows electric current to enter or leave an electrical system, serving as the site where important oxidation and reduction (redox) reactions take place. Electrodes are broadly classified by how they interact with their surrounding environment, their material composition, and their specific application.
Electrode wear – It is the gradual deterioration, deformation, or loss of material from an electrode’s tip during manufacturing or electrical processes. It very frequently refers to tool degradation in electrical discharge machining (EDM) or tip deformation in resistance spot welding.
Electrode wear ratio – It is a key metric in electrical discharge machining (EDM) which measures tool deterioration. It is defined as the volume of material lost from the tool electrode divided by the volume of material removed from the work-piece.
Electrode, welding – In arc welding, it is a current-carrying rod which supports the arc between the rod and work-piece, or between two rods as in twin carbon-arc welding. It may or may not furnish filler metal. In resistance welding, it is a part of a resistance welding machine through which current and, in majority of the cases, pressure is applied directly to the work-piece. The electrode can be in the form of a rotating wheel, rotating roll, bar, cylinder, plate, clamp, chuck, or modification thereof. In arc and plasma spraying, it is the current-carrying components which support the arc.
Electrode wire – It is an electrical conductor which carries current to create an electric arc or electrical contact in specialized processes. Depending on the application, it can either melt to act as filler material (in welding) or remain intact (in machining and medical procedures).
Electro-dialysis – It is an electro-chemical separation process that uses electrically charged membranes and an electrical potential difference to separate ionic species from an aqueous solution. It is a method for purifying colloidal solutions by applying an electric field to remove ionic impurities. Essentially, it is a membrane process where ions are transported from one solution to another by an electrical force.
Electro-dialysis, and electro-dialysis reversal processes – These are water softening processes which are driven by direct current in which ions (as opposed to water in pressure driven methods) flow through ion selective membranes to electrodes of opposite charge.
Electro-dialysis method – It is an electro-chemical separation process which uses a direct electrical current to transport dissolved salt ions through selective ion-exchange membranes. It actively pulls contaminants out of a liquid feed rather than forcing water through a filter, making it a highly effective method for water desalination.
Electro-dialyzer – It is a piece of equipment which consists of a stack of alternating anion and cation exchange membranes arranged between two electrodes, facilitating the electro-chemical separation of ions from a desalted stream to a concentrated solution under the influence of an electrical potential.
Electro-discharge machining – it is a non-traditional, electro-thermal manufacturing process which removes material from conductive work-pieces using rapidly recurring electrical sparks. The work-piece and electrode are submerged in dielectric fluid, and sparks melt / vapourize material at temperatures exceeding 10,000 deg C, allowing high-precision machining of hard materials without direct contact.
Electro-dynamic interaction – It is the mutual force and energy exchange between electric currents, charges, and the electro-magnetic fields they produce. It governs how changing electrical and magnetic phenomena convert energy, propagate signals, and produce physical movement.
Electro-extraction – It is also known as electro-winning. It is an electro-chemical process which uses electric current to recover or extract metals from a liquid, typically a metal-rich leach solution. It works by depositing purified metal ions onto a cathode, making it a critical method for producing high-purity non-ferrous metals like copper, gold, and zinc.
Electro-filtration – It is an advanced separation process which overlays an electric field onto a standard filtration or membrane system. By applying a direct current, it drives charged particles away from the filter media to prevent clogging (fouling) and drastically accelerates separation rates for colloidal suspensions.
Electro-formed mould – It is a mould made by electro-plating metal on the reverse pattern of the cavity. Molten steel can then be sprayed on the back of the mould to increase its strength.
Electro-forming – It is the process by which articles or shapes can be exactly reproduced by electrode-position on a mandrel or form that is later removed, leaving a precise duplicate of the original. In certain applications, the mandrel is designed to remain as an integral part of the final electro-formed object. Electro-forms themselves can be used as parents or masters, normally with special passivating treatments so the secondary electro-form can be easily removed. The same or similar electro-deposition additives as those used for electro-plating are needed for electro-forming for controlling deposit stress, grain size, and other resultant mechanical properties in order to produce high-quality electro-forms.
Electro-fuels – These are also called e-fuels. These are a class of synthetic, carbon-neutral drop-in replacement fuels. They are engineered by storing electrical energy from renewable sources in the chemical bonds of liquid or gaseous fuels, such as e-diesel, e-kerosene, or e-methane.
Electro-galvanized coatings – These coatings are created by applying zinc to steel sheets and strips by electro-deposition.
Electro-galvanized coating process – It is also called electro-galvanizing. It is a process which deposits a thin, uniform layer of zinc onto steel through electrolytic action, providing superior corrosion protection and excellent paint adhesion. Using a zinc anode, electrolyte solution, and steel cathode, it creates a smooth coating, typically 7 micro-meters to 40 micro-meters thick, without disrupting edge integrity.
Electro-galvanized steel – It is a type of cold-rolled steel coated with a thin, uniform layer of zinc applied through an electrolytic process. It is designed to improve corrosion resistance while providing a smooth, high-quality surface finish suitable for painting, normally used in automotive parts, appliances, and electronics.
Electro-galvanizing – It is the electro-plating of zinc upon iron or steel. Electro-galvanizing the sheet and wire in coil form produces a thin, uniform coating of pure zinc with excellent adherence. The coating is smooth, readily prepared for painting by phosphatizing, and free of the characteristics-spangles of hot dip zinc coatings. Electro-galvanizing can be used where a fine surface finish is needed. The appearance of the coating can be varied by additives and special treatments in the plating bath.
Electro-galvannealed steel – It is the galvannealed steel which is produced by electro-plating the zinc-iron alloy directly onto the surface of the strip, similar to the way zinc-nickel electro-galvanized coatings are produced. The electro-plated galvanneal coating contains the same phases as a hot-dipped and furnace alloyed galvanneal coating, but the phases in the electro-plated coating are uniformly and homogeneously distributed as opposed to the layered structure which develops in the hot dip galvannealed process. This coating homogeneity, combined with the lack of a continuous gamma layer at the steel / coating interface, results in a considerably higher resistance to powdering and flaking in the electro-plated coating as compared to the furnace-alloyed coating.
Electro-gas welding – It is an arc welding process which produces coalescence of metals by heating them with an arc between a continuous filler metal electrode and the work-piece. Moulding shoes are used to confine the molten weld metal for vertical position welding. The electrodes can either be flux cored or solid. Shielding may or may not be obtained from an externally supplied gas or mixture.
Electrogenic bacteria – These are microorganisms which can oxidize organic matter and transfer electrons either to an anode or from a cathode, playing an important role in the operation of microbial fuel cells (MFCs) and contributing to sustainable energy generation.
Electro-gravimetry – it is the oldest electro-analytical technique. In it, the element of interest is to be deposited electrolytically onto an electrode and weighed. Unlike majority of the electro-chemical techniques, the reaction is to be frequently allowed to go to completion efficiently, prolonging analysis times. However, the technique is more accurate (0.1 %) than controlled potential coulometry (0.2 % to 5 %) or polarography (2 %). Use of efficient stirring lessens analysis time. Overall analysis time depends on the technique used.
Electro-hydraulic forming – It is a high-energy-rate sheet metal forming process which uses a high-voltage electrical discharge between two electrodes submerged in a liquid (normally water) to create a shock wave. This sudden shock wave acts as a flexible, high-speed punch, forcing a work-piece into a die to take its shape.
Electro-hydraulic gravity-drop hammer – It is a type of industrial forging machine which uses electro-hydraulic system to raise a heavy ram (hammer head) and then releases it to fall through gravity onto a metal work-piece, using the impact energy to form the metal within closed dies. In these machines, the lifting mechanism involves hydraulic oil pressure, typically working against an air cushion which both accelerates the downward blow and softens the return stroke.
Electro-hydro-dynamic printing – It is an advanced additive manufacturing technique which uses an intense electric field to pull ultra-fine ink droplets or continuous streams from a nozzle. It bypasses the resolution limits of conventional inkjet printers, enabling direct-write, high-resolution nano-scale patterning for flexible electronics.
Electro-kinetic phenomena – These refer to a group of effects resulting from the interaction between mechanical and electrical forces at the interface of a charged solid surface and an adjacent liquid. These processes are driven by the ‘electrical double layer’ of ions which forms at the boundary, making them highly important in microfluidics, soil mechanics, and chemical engineering. The four main types of electrokinetic phenomena include electro-osmosis, electrophoresis, streaming potential, and sedimentation potential.
Electro-kinetic potential – This potential which is sometimes called zeta potential, is a potential difference in the solution caused by residual, unbalanced charge distribution in the adjoining solution, producing a double layer. The electro-kinetic potential is different from the electrode potential in that it occurs exclusively in the solution phase, i.e., it represents the reversible work necessary to bring unit charge from infinity in the solution up to the interface in question but not through the interface.
Electro-kinetic process – It is an advanced, sustainable technique that applies a low-intensity direct current (DC) to a porous medium, such as ore, soil, sludge, or tailings, to induce the movement of water, ions, and charged particles towards electrodes for separation and recovery. This process is normally utilized for treating fine-grained, low-permeability materials where conventional hydraulic methods (like heap leaching) are inefficient.
Electro-kinetic treatment – It is a technique which applies a low-intensity direct electric current to low-permeability soils or porous materials (like concrete). It induces fluid and ion movement, making it highly effective for environmental cleanup and structural ground improvement.
Electro-less cobalt (Co) alloy plating – It is an autocatalytic chemical process that deposits a layer of cobalt or cobalt-alloy (typically with phosphorus or boron) onto a substrate without using external electricity. It involves reduction of metal ions in a bath to form uniform, wear-resistant, and frequently magnetic films on conductive or non-conductive surfaces.
Electro-less composite plating – It is an autocatalytic chemical process which co-deposits fine solid particles (such as carbides, oxides, or polymers) within a metallic or alloy matrix. By combining electro-less plating with suspended micro-particles, engineers create advanced surfaces with customized wear resistance, thermal properties, or self-lubrication.
Electro-less copper plating – It is a chemical process which deposits a continuous copper layer onto a substrate without using an external electrical power source. It relies on an autocatalytic redox reaction, where a reducing agent donates electrons to copper ions in the solution, converting them into metallic copper on the surface.
Electro-less deposition – It is an auto-catalytic process where the substrate develops a potential in a plating bath containing metallic ions, reducing agent, complexing agent, stabilizer and other components.
Electro-less metal deposition – It refers to a chemical process used to deposit metal layers, such as nickel or cobalt, onto substrates without the need for external electrical current, enabling selective deposition which is highly uniform and effective for creating barrier and capping layers in metallization applications. Unlike traditional electro-plating, it uses no external electrical current. Instead, electrons are supplied through a controlled chemical reduction / oxidation (redox) reaction within an aqueous bath.
Electro-less nickel – It is a chemical coating technique which deposits a uniform nickel-alloy layer onto a substrate without using electrical current. It relies on an auto-catalytic chemical bath where reducing agents convert nickel ions to metallic nickel, resulting in exceptional corrosion resistance, uniform thickness, and hardness.
Electro-less nickel coating – It is an autocatalytic, chemical process which deposits a uniform, dense, nickel-phosphorus (or nickel-boron) alloy layer onto a substrate without using electrical current. It offers superior corrosion resistance, wear resistance, and precise, consistent thickness on complex geometries compared to electro-plating.
Electro-less nickel-phosphorus coating – It is an autocatalytic chemical process which deposits an even, dense layer of nickel-phosphorus alloy onto a solid substrate (metal or plastic) without using electrical current. It provides superior corrosion resistance, high hardness, wear resistance, and uniform thickness across complex geometries.
Electro-less nickel plating – It is used to deposit nickel without the use of an electric current. The coating is deposited by an auto-catalytic chemical reduction of nickel ions by hypo-phosphite, amino-borane, or boro-hydride compounds. Two other methods have been used commercially for plating nickel without electric current, including (I) immersion plating on steel from solutions of nickel chloride and boric acid at 70 deg C, and (ii) decomposition of nickel carbonyl vapour at 180 deg C. Immersion deposits, however, are poorly adherent and non-protective, while the decomposition of nickel carbonyl is expensive and hazardous. Hence, only electro-less nickel plating has gained wide acceptance.
Electro-less plating – It is a process in which metal ions in a dilute aqueous solution are plated out on a substrate by means of auto-catalytic chemical reduction. It is also the deposition of conductive material from an auto-catalytic plating solution without the application of electrical current.
Electro-luminescence – It is an optical and electrical phenomenon where a material, typically a semi-conductor or di-electric phosphor, emits cold light (non-thermal light) in response to an electric current passed through it or a strong electric field. It involves the radiative recombination of electrons and holes within a solid-state material, frequently utilizing dopants.
Electrolysis – It is the chemical change resulting from the passage of an electric current through an electrolyte. It is also the separation of chemical components by the passage of current through an electrolyte. In electrolysis, an electric current is passed through a solution containing dissolved metals, causing the metals to be deposited onto a cathode.
Electrolysis cell – It is an electro-chemical device which uses an external direct current (DC) to drive a non-spontaneous redox reaction. It converts electrical energy into chemical energy and is fundamentally used in engineering to split chemical compounds, extract metals, or coat surfaces.
Electrolysis, grid – Grid electrolysis is the process of using electricity from the power grid to operate electrolyzers, which facilitates the production of green hydrogen while optimizing for low carbon emissions and electricity costs. This method integrates grid power to improve operational flexibility and efficiency in alkaline water electrolysis systems.
Electrolysis of water – It is the electro-chemical process of using electrical energy to split water H2O into pure hydrogen H2 and O2 gases. This technique is central to scaling carbon-free green energy, chemical manufacturing, and power-to-X (PtX) applications. Water splitting is carried out in a device called an electrolyzer, which consists of at least two electrodes (an anode and a cathode) submerged in an electrolyte.
Electrolysis system – It is an electro-chemical assembly which converts electrical energy into chemical energy. It utilizes a direct electric current (DC) to drive a non-spontaneous chemical reaction. It typically decomposes compounds (like water or brine) to produce high-value gases (such as hydrogen and oxygen) or to extract and refine metals.
Electrolysis technology – It is a process which uses electrical energy to decompose water into hydrogen and oxygen, enabling the production of clean fuels like hydrogen and ammonia, which can be utilized in sustainable energy applications. It is an important component of power-to-X (PtX) solutions, facilitating the conversion of renewable energy into storable fuels.
Electrolyte – It is a chemical substance or mixture, normally liquid, containing ions which migrate in an electric field. It is also a chemical compound or mixture of compounds which when molten or in solution conducts an electric current.
Electrolyte additives – These are substances added to electrolytes to improve thermal and chemical stability, improve wettability, and promote film formation. They function to mitigate undesirable side reactions at the electrode-electrolyte interface, leading to the formation of stable solid electrolyte interphase (SEI) layers. These are specialized functional chemicals (typically below 5 %) added to base electrolytes. Additive engineering involves deliberately selecting and tuning these trace compounds to optimize energy storage devices (like batteries), specifically by stabilizing the electrode-electrolyte interface and improving ionic conductivity or safety.
Electrolyte combination – It is the physical blending of multiple salts, solvents, or additives in an electrolyte formulation. This targeted technique is mainly used in battery and electro-chemical systems to optimize overall performance metrics like ionic conductivity, viscosity, capacity retention, and cycling stability.
Electrolyte concentration – It refers to the quantitative measure of dissolved solute (such as salts, acids, or bases) in a solvent. It dictates the density of charge carriers in the fluid, which directly determines the medium’s electrical conductivity, ionic mobility, and overall electro-chemical performance. In engineering applications, like designing batteries, fuel cells, or electro-plating processes, concentration is a critical parameter.
Electrolyte interface – It involves designing and modifying the boundary layer between an electrode and an electrolyte in electro-chemical systems (like batteries) to optimize performance, stability, and safety. It specifically targets and controls the solid electrolyte interphase (SEI) on anodes and cathode electrolyte interphase (CEI) on cathodes.
Electrolyte ions – These are charged particles (atoms or molecules) which enable electrical conductivity in an electrolyte by freely moving to balance charge and carry current. These ions serve as the active transport medium for transferring energy in systems like batteries, supercapacitors, and sensors.
Electrolyte layer – It is the design of ionic-conducting barriers in electro-chemical devices (e.g., batteries, fuel cells). It involves tailoring layer compositions, thicknesses, and interfacial properties to maximize ion mobility, prevent current leakage, and prevent catastrophic dendrite formation.
Electrolytes for batteries – These refer to solvent systems which facilitate the dissociation of salts into ions, enabling ionic conductivity within the battery. These can include different organic solvents, such as carbonates and ethers, which are selected based on their dielectric constant, viscosity, and electro-chemical stability to optimize performance in applications like sodium-ion batteries.
Electrolytes for fuel cells – These are substances which can be alkaline, acid, molten carbonates, or ceramic, facilitating ion conduction necessary for the electro-chemical reactions in fuel cells. Common examples include potassium hydro-oxide (KOH) and phosphoric acid, which are utilized for their specific conductive properties and compatibility with different operational conditions.
Electrolyte species – These are the specific dissolved ions (e.g., Li+, Na+. Cl-) in a solvent which carry electric charge and facilitate mass transport. Electrolyte species refers to the computational modelling, tracking, and thermodynamic tailoring of these ions to optimize the performance, efficiency, and safety of electro-chemical devices. Engineers treat the electrolyte as a multi-component mixture where individual species dictate mass, charge, and thermal transport. In system modeling, defining these species involves specific engineering work-flows.
Electrolyte stability – It is the ability of an ion-conducting medium to resist decomposition or degradation when exposed to specific voltages, temperatures, and chemical reactions. It dictates a system’s safety, efficiency, and operational lifespan in devices like batteries, supercapacitors, and fuel cells.
Electrolyte supply – It refers to the system which continuously delivers a conductive fluid (electrolyte) to an electro-chemical cell or machining gap. It manages flow rates, pressure, and filtration to remove heat, gas bubbles, and debris, ensuring stable operation, efficient ion transfer, and process continuity.
Electrolytic bath – It is a tank or container filled with an electrolyte solution (normally water-based or molten salts) through which direct electrical current is passed. It serves as the physical medium for electro-chemical processes like electro-plating, electro-polishing, and metal extraction.
Electrolytic brightening – It is a technique normally used to prepare metallographic samples, in which a high polish is produced making the sample the anode in an electrolytic cell, where preferential dissolution at high points smooths the surface.
Electrolytic capacitor – It is a polarized electronic component which uses an ion-conductive liquid or solid electrolyte to achieve a considerably higher capacitance-per-unit volume than standard electro-static capacitors. It works by using an anodized metal oxide layer as its main dielectric.
Electrolytic cell – It is an assembly, consisting of a vessel, electrodes, and an electrolyte, in which electrolysis can be carried out. It is a unit apparatus in which electro-chemical reactions are produced by applying electrical energy, or which supplies electrical energy as a result of chemical reactions and which includes two or more electrodes and one or more electrolytes contained in a suitable vessel.
Electrolytic chromium coated steel – It is a type of steel which has a thin layer of chromium electroplated onto its surface. This chromium coating is typically less than a micrometer thick and is intended to protect the steel from corrosion and improve its appearance.
Electrolytic cleaning – It is a process of removing soil, scale, or corrosion products from a metal surface by subjecting it as an electrode to an electric current in an electrolytic bath.
Electrolytic corrosion – It is the corrosion by means of electro-chemical or mechanical action.
Electrolytic copper – It is the copper which has been refined by electro-deposition, including cathodes which are the direct product of the refining operation. Refinery shapes cast from melted cathodes, and, by extension, fabricators’ products made therefrom. Normally when this term is used alone, it refers to electrolytic tough pitch copper without elements other than oxygen being present in significant quantities.
Electrolytic deposition – It is the deposition of a conductive material from a plating solution by the application of electrical current. It is also the deposition of a substance on an electrode by passing electric current through an electrolyte. Electro-plating, electro-forming, electro-refining, and electro-winning result from electro-deposition.
Electrolytic etching – It is a surface treatment technique which uses an electric current (direct current) and an electrolytically conductive solution to selectively dissolve and remove metal from the surface of a work-piece. Unlike conventional chemical etching, which relies solely on harsh acids, electrolytic etching acts as the reverse of electroplating, where the work-piece acts as the anode, allowing for precise, controlled material removal.
Electrolytic extraction – It is the removal of phases by using an electrolytic cell containing an electrolyte which preferentially dissolves the metal matrix.
Electrolytic galvanized steel – t is cold rolled steel to which a coating of zinc is applied by electro-deposition. It is used for applications in which corrosion resistance and paintability is a primary concern.
Electrolytic grinding – It is a combination of grinding and machining wherein a metal-bonded abrasive wheel, normally diamond, is the cathode in physical contact with the anodic work-piece, the contact being made beneath the surface of a suitable electrolyte. The abrasive particles which produce grinding act as non-conducting spacers permitting simultaneous machining through electrolysis.
Electrolytic hydrogen production – It is the process of splitting water molecules (H2O) into hydrogen and oxygen using an electric current. By utilizing direct current (DC) in a device called an electrolyzer, high-purity hydrogen gas is released at the cathode and oxygen at the anode.
Electrolytic machining – It is the controlled removal of metal using an applied potential and a suitable electrolyte to produce the shapes and dimensions desired.
Electrolytic pickling – It is the pickling in which electric current is used, the work-piece being one of the electrodes.
Electrolytic polishing – It is an electrochemical polishing process in which the metal to be polished is made the anode in an electrolytic cell where preferential dissolution at high points in the surface topography produces a specularly reflective surface.
Electrolytic powder – It is the powder produced by electro-deposition or by pulverizing of an electrodeposit.
Electrolytic protection – The preferred term is cathodic protection which is the partial or complete protection of a metal from corrosion by making it a cathode, using either a galvanic or an impressed current.
Electrolytic refining – It is the process of purifying metal ingots which are suspended as anodes in an electrolytic bath, alternated with refined sheets of the same metal which act as starters or cathodes.
Electrolytic system – It is an electro-chemical assembly which uses an externally applied direct current (DC) to drive a non-spontaneous oxidation-reduction (redox) reaction. It converts electrical energy into chemical energy, and is foundational for applications like water electrolysis (hydrogen production), metal refining, electro-plating, and corrosion prevention.
Electrolytic tank – It refers to two distinct concepts: an electrochemical reactor used to drive chemical changes using electricity (e.g., hydrogen production), or an analog computer used to map potential fields and solve complex differential equations.
Electrolytic tin coated sheets – These are cold rolled sheets coated with tin by electro-deposition through an acid or alkaline process.
Electrolytic tin plate – It is light-gauge, low-carbon, cold reduced steel on which tin has been electro-deposited. It is also the black plate coated with tin-by-tin electron deposition.
Electrolytic tin plating – It is a process where a thin layer of tin is deposited onto a metal surface using an electric current. This is achieved by immersing the object in a tin-containing electrolyte bath and passing an electrical current through it. The object to be plated acts as the cathode, and the tin anode gradually dissolves, depositing tin ions onto the object’s surface.
Electrolytic tough pitch – It is a term used for describing the method of raw copper preparation to ensure a good physical-grade and electrical-grade copper-finished product.
Electrolytic tough pitch (ETP) copper – It is pure copper (with a maximum of 0.0355 % impurities) refined by the electrolytic refining process. It is the most widely used grade of copper. It has a minimum conductivity rating of 100 % IACS (International Annealed Copper Standard). It is required to be 99.9 % pure. It has 0.02 % to 0.04 % oxygen content (typical). Electrical wiring is the most important use of this grade of copper.
Electrolyzer – It is a device which combines oxidation and reduction reactions driven by electricity to produce separate streams of hydrogen gas and oxygen gas through the process of electrolysis.
Electrolyzer technology – It refers to systems which produce hydrogen and oxygen gases from water through the process of electrolysis, playing an important role in generating clean and sustainable hydrogen for environmental sustainability and the transition to clean energy.
Electro-magnet – It is a magnet which generates a magnetic field from an electric current.
Electro-magnetic – It refers to the physical relationship between electricity and magnetism, describing forces, fields, and radiation produced by moving or accelerating electric charges. It involves a unified field composed of perpendicular electric and magnetic components and includes phenomena across the spectrum, from radio waves to gamma rays.
Electro-magnetic-acoustic transducer – It is a non-contact ultrasonic testing device which generates and detects sound waves within conducting materials through electro-magnetic induction, eliminating the need for coupling liquids. It works by interacting high-frequency magnetic fields with static fields to create Lorentz forces or magnetostriction directly inside the material.
Electromagnetic actuation – It is a mechanism which converts electrical signals into mechanical motion using the principles of electro-magnetism. When electrical current passes through a coil, it generates a magnetic field which moves a ferro-magnetic component (or armature), delivering precise and rapid forces for controlling, locking, or moving mechanical systems.
Electro-magnetic analysis – It is the study of how electric and magnetic fields interact with physical objects and devices. By utilizing mathematical models based on Maxwell’s equations and computational simulations, engineers predict electro-magnetic behaviour to optimize performance, prevent interference, and ensure regulatory compliance.
Electro-magnetic balance – it is frequently called an electro-magnetic force compensation balance. It is a high-precision weighing device which uses an electro-magnetic force to counter-balance the weight of an object. Instead of using physical weights or strain gauges, it continuously adjusts an electric current through a coil to return the weighing pan to a precise null position.
Electro-magnetic braking – Electro-magnetic braking of the liquid steel flow in the mould of a continuous casting machine improves the quality of the cast steel by reducing the penetration of non-metallic inclusions.
Electro-magnetic casting – It is an advanced, contactless manufacturing process which uses alternating electro-magnetic fields to shape, support, and control molten metal during solidification. By inducing eddy currents which interact with the magnetic field, this method exerts a ‘pinch’ force (Lorentz force) on the molten metal, allowing it to solidify without touching the mould walls. This technique is a combination of magneto-hydro-dynamics (MHD) and conventional casting, frequently used for continuous casting to considerably improve the surface quality of metal ingots.
Electro-magnetic coil – It is a coiled electrical conductor, typically insulated copper wire, designed to generate a magnetic field from electric current, or conversely, to induce voltage when exposed to a varying magnetic field. It serves as the fundamental bridge between electrical and mechanical or magnetic energy.
Electro-magnetic compatibility – It is the ability of electrical and electronic systems to operate properly in their intended environment without causing or experiencing unacceptable electro-magnetic interference (EMI) with other devices. It ensures that devices do not emit excessive interference and have sufficient immunity to function nearby without disruption.
Electro-magnetic coupling – It is the transfer of energy between two or more circuits or structures through electric (capacitive) or magnetic (inductive) fields. It occurs when the electro-magnetic field produced by a source circuit interacts with a victim circuit, and can be intentionally designed or completely unintentional.
Electro-magnetic disturbance – It is an unintended or unwanted electro-magnetic phenomenon, such as an electro-magnetic field, electrical noise, or voltage surge, which can interrupt, obstruct, or degrade the effective performance of electrical and electronic equipment.
Electro-magnetic environmental effect – It is the impact of the total electro-magnetic environment, including radiated and conducted emissions, on the operational capability of equipment, and systems. Electro-magnetic environmental effect (E3) ensures systems can operate safely without causing or suffering electromagnetic interference (EMI).
Electro-magnetic field – It is the field produced by moving electric charges and magnetic fields.
Electro-magnetic flowmeter – It is an industrial instrument that measures the volumetric flow rate of electrically conductive fluids. It is widely utilized across engineering sectors for its high accuracy and unobstructed design.
Electro-magnetic focusing device – It is a device which effectively increases the angular aperture of the electron beam illuminating the object, rendering the focusing more critical.
Electro-magnetic forming – It is an assembly technique which is widely used to both join and shape metals and other materials with precision and rapidity, and without the heat effects and tool marks associated with other techniques. It is also known as magnetic pulse forming. The electro-magnetic forming process uses the direct application of a pressure created in an intense, transient magnetic field. Without mechanical contact, a metal work-piece is formed by the passage of a pulse of electric current through a forming coil. It is also known as magnetic pulse forming.
Electro-magnetic generator – It is an electro-mechanical device which converts mechanical energy into electrical energy using the principle of electro-magnetic induction. It operates by rotating a conductive coil within a magnetic field or a magnetic field around a coil, which induces an electric current in the wire.
Electro-magnetic induction – It is the production of current in a circuit by the change of magnetic field intersecting the circuit.
Electro-magnetic interference – It is an unwanted disturbance to the performance of an electronic device caused by an electro-magnetic field. This interference can be generated by natural or human-made sources and can disrupt circuits and prevent them from working correctly.
Electro-magnetic interference (EMI) shielding – It is the practice of using conductive or magnetic materials to reduce, block, or redirect electro-magnetic waves. It acts as a barrier to prevent unwanted external electro-magnetic radiation from interfering with sensitive electronic components or to stop emitted signals from interfering with surrounding devices.
Electro=magnetic leakage – It is the unintentional emission of electro-magnetic energy from a system, or the unwanted penetration of external electro-magnetic fields into a shielded system. It occurs when signals bypass designed containment through gaps, enclosures, cables, or connectors.
Electro-magnetic lens – It is an electro-magnet designed to produce a suitably shaped magnetic field for the focusing and deflection of electrons or other charged particles in electron-optical instrumentation.
Electro-magnetic levitation – It is a technique which uses active or induced magnetic fields to counteract gravity and suspend an object without physical contact. It relies on precise control of magnetic forces (through attraction or repulsion) and active feedback systems to ensure stability.
Electro-magnetic loads – These are the forces and stresses exerted on structural components because of the interaction of magnetic fields and electric currents. These loads are typically categorized into two types namelyhttps://www.sciencedirect.com/topics/computer-science/electromagnetic-loads Lorentz forces and ferro-magnetic forces.
Electro-magnetic methods – They detect the electrical properties of the subsurface by inducing electro-magnetic energy within the subsurface and measuring the response of earth materials. Normally, electro-magnetic geophysical instruments output a time-varying electric current into its transmitter coil, or loop. As the current travels in the transmitter loop, it generates a magnetic field that has the same frequency and phase as the current. This induced field propagates lines of force that penetrate the earth.
Electro-magnetic model – It is a mathematical or computational representation of electric and magnetic fields, typically based on Maxwell’s equations. It is used to simulate, analyze, and predict how electro-magnetic waves interact with physical objects, materials, and circuits to optimize device performance.
Electro-magnetic parameters – These are fundamental material properties which define how a medium interacts with electric and magnetic fields. They dictate how electro-magnetic waves propagate, reflect, or attenuate.
Electro-magnetic pollution – It is also known as electro-smog. It is the pervasive presence of undesirable, man-made electro-magnetic energy in the environment. It ranges from low-frequency radiation (power grids) to high-frequency radio waves, such as Wi-Fi (wireless fidelity) cell towers, which can degrade electronic equipment performance and pose potential health hazards.
Electro-magnetic properties – These properties define how materials interact with electric and magnetic fields. They govern how devices conduct electricity, generate magnetic fields, and resist electro-magnetic interference. These fundamental material characteristics dictate the efficiency and functionality of everything from power grids to micro-chips.
Electro-magnetic pulse – It is a sudden, intense burst of electro-magnetic radiation which uses damaging, high-voltage surges in electrical and electronic systems. Caused by nuclear detonations (especially high-altitude), lightning, or solar coronal mass ejections (CMEs), it can destroy communication systems, power grids, and electronics over large areas. Electro-magnetic pulses (EMPs) work by creating rapidly changing electric and magnetic fields which induce high-voltage spikes, known as transient electro-magnetic waves, which exceed the tolerance of electrical devices.
Electro-magnetic radiation – It is the energy propagated by an electro-magnetic field. It consists of radio waves, light and other radiation which travels through space at the speed of light.
Electro-magnetic shielding materials – These can be defined as materials used to block electro-magnetic wave interference, hence reducing the harm caused by electro-magnetic pollution and protecting human health and electronic devices.
Electro-magnetic signature – It is the unique pattern of electro-magnetic energy emitted, reflected, or scattered by a device, system, or object. It functions like a physical fingerprint, shaped by a target’s geometry, material composition, and electrical activity, and is measured across different frequencies, amplitudes, and polarizations. Electro-magnetic signatures are critical for two main applications namely signature management and diagnostic analysis.
Electro-magnetic spectrum – It is the range of frequencies of electro-magnetic radiation. The electro-magnetic spectrum includes the several approximate wavelength regions as given in Tab 1.
| Tab 1 Electro-magnetic spectrum regions and their wavelengths | ||
| Spectrum region | Wavelength | |
| Angstrom | Nano meter | |
| Gamma ray | 0.005 – 1.4 | 0.0005 – 0.14 |
| X-ray | 0.1 – 100 | 0.01 -10 |
| Far ultra-violet | 100-2000 | 10-200 |
| Near ultra-violet | 2000 -3800 | 200-380 |
| Visible | 3800 -7800 | 380-780 |
| Near infra-red | 7800-30,000 | 0.78-3 micro-metre |
| Middle infra-red | 30,000-300,000 | 3-30 micro-meter |
| Far infra-red | 300,000-3 million | 30-300 micro-meter |
| Micro-wave | 3 million- 10 billion | 0.3 millimeter to 1 metre |
Electro-magnetic stirring – It is the process by which a high level of stirring efficiency can be achieved through interaction between the magnetic field from the static induction coil and the electrically conducting metal bath. Electromagnetic stirring generates a fluid flow by the Lorenz force provided by a linear induction motor. EMS technology has been used in the continuous casting of steel for several years but the effect of the application and subsequent benefits of stirring the liquid core depends very much on section size, steel grade, and product application. It differs from the conventional mechanical and decompression types as it is a non-contact stirrer in which no part touches the liquid steel.
Electro-magnetic survey – It is a geophysical survey method which measures the electro-magnetic properties of the rocks. Electromagnetic surveys are based on variations of electric conductivity in the rock mass. A transmitter is used for creating a primary alternating electromagnetic field. Induced current produces a secondary field in the rock mass. The resultant field is traced and measured, thus revealing the conductivity of the underground masses.
Electro-magnetic techniques – These techniques are used for residual stress measurements. Residual stresses in materials can be non-destructively measured by a variety of methods, including x-ray diffraction, ultrasonic, and electro-magnetic techniques. With electro-magnetic techniques, one or more of the magnetic properties of a material (such as permeability, magnetostriction, hysteresis, coercive force, or magnetic domain wall motion during magnetization) are sensed and correlated to stress. These techniques rely on the change in magnetic properties of the material caused by stress, which is known as the magneto-elastic effect. These techniques, hence, apply only to ferro-magnetic materials, such as steel.
Electro-magnetic transient – it is a rapid, short-duration disturbance in an electrical power system. It involves the fast exchange of energy between a system’s magnetic and electric fields, resulting in high-frequency voltage and current spikes, surges, or waveform distortions which last from a few micro-seconds to milli-seconds.
Electro-magnetic water conditioning – It is frequently referred to as magnetic water treatment. It involves passing water through a strong magnetic field. The goal is to alter the behaviour of dissolved minerals, particularly calcium and magnesium, to prevent or reduce scale formation. While the water’s chemical composition remains unchanged, the magnetic field is claimed to alter the minerals’ crystalline structure, making them less likely to adhere to surfaces.
Electro-magnetic wavelength – It is the physical distance a wave takes to complete one full cycle of oscillation, measured between two consecutive corresponding points (like peaks or troughs). It dictates how electro-magnetic (EM) energy propagates through space and interacts with physical matter and antenna structures.
Electro-magnetic waves – These are oscillating electric and magnetic fields which propagate through space, transferring energy and momentum without requiring a medium. They are formed when an electric field interacts with a magnetic field, creating a self-sustaining wave. These waves are transverse, meaning the electric and magnetic fields oscillate perpendicular to each other and to the direction of propagation.
Electro-magnetism – It is the science of electric fields, magnetic fields, currents, charges, and forces. It is an interaction which occurs between particles with electric charge through electro-magnetic fields. The electro-magnetic force is one of the four fundamental forces of nature. It is the dominant force in the interactions of atoms and molecules. Electro-magnetism can be thought of as a combination of electrostatics and magnetism, which are distinct but closely intertwined phenomena.
Electro-mechanical – It is a system which has both an electrical component and a mechanical component, such as a motor or a relay.
Electro-mechanical actuation – It is the process of converting electrical energy into controlled mechanical motion (force, torque, or displacement) using electric motors and mechanical drive mechanisms. It translates electronic control signals into physical, mechanical work. These systems replace traditional fluid-based methods (such as hydraulics and pneumatics) with cleaner, more digitally controllable, and energy-efficient architectures.
Electro-mechanical behaviour – It defines how a system, component, or material interacts across both electrical and mechanical domains. It encompasses two main processes namely (i) the conversion of electrical signals into mechanical motion (e.g., actuators), and (ii) the generation of electrical energy from mechanical movement (e.g., generators). It represents the dynamic interplay between electrical currents, magnetic fields, and physical forces.
Electro-mechanical components – These are devices which combine electrical and mechanical processes to transfer motion, data, or power. They bridge the electronic and physical realms by converting electrical signals into mechanical movement, or vice versa.
Electro-mechanical coupling – It describes the interaction and mutual conversion between electrical and mechanical energy within a system, where a change in electrical state directly influences mechanical properties and vice versa.
Electro-mechanical coupling factor – It is a fundamental engineering metric which measures the efficiency of a piezoelectric, magnetostrictive, or electrostrictive material in converting electrical (or magnetic) energy into mechanical energy, and vice versa. The coupling factor is fundamentally defined by the energy conversion ratio.
Electro-mechanical engineering – It is the cross-disciplinary field focused on the design, development, and integration of electrical, electronic, and mechanical systems. Component engineers in this space are responsible for evaluating, testing, and standardizing these dual-nature parts to ensure they meet exact reliability, cost, and lifecycle requirements.
Electro-mechanical mud gun – A mud gun is used to close the tap hole after tapping is complete. A quantity of the tap hole mass is pushed by the mud gun to fill the worn hole and to maintain a quantity of the tap hole mass (the mushroom) within the hearth. The mud gun is normally held in place on the tap hole until the tap hole mass cures and the tap hole is securely plugged. It has three separate electric drives for unit swing, barrel positioning, and ramming. Hence several separate motions are needed for accurate positioning of the mud gun at the tap hole. Tap hole mass injection pressure is in the range of only 5 mega-pascals to 8 mega-pascals. The electro-mechanical mud gun is latched to the furnace to keep it in place during plugging.
Electro-mechanical polishing – It is an attack-polishing method in which the chemical action of the polishing fluid is improved or controlled by the application of an electric current between the sample and the polishing wheel.
Electro-mechanical properties – These properties refer to the behavioural characteristics of a material, component, or system which arise from the interaction between mechanical forces and electrical fields. This important discipline focuses on how electrical inputs trigger mechanical movement, or how mechanical deformation generates electrical signals.
Electro-mechanical system – It integrates electrical and mechanical components to generate, control, or convert energy. These systems process electrical signals to produce physical movement or utilize mechanical forces to generate electrical energy, forming the backbone of modern automation, robotics, and manufacturing equipment.
Electro-mechanical transducer – It is a device which converts electrical energy into mechanical energy, or vice versa. These devices act as bridges between electrical systems and physical motion, serving as important components in sensors (measuring physical displacement) and actuators (creating physical movement).
Electro- mechanical valves – These valves have electro magnets controlling whether the valve is open or closed. These valves can only be fully open or fully closed.
Electro-mechanics – It is a hybrid engineering discipline which merges electrical and mechanical systems. It focuses on the design, analysis, and manufacture of devices which convert electrical energy into mechanical movement, or vice versa, using electrical signals, magnetic fields, and physical components.
Electro-metallurgy – It that branch of metallurgical engineering which deals with the industrial recovery or processing of metals and alloys by electric or electrolytic methods.
Electromigration– It is the gradual movement of metal atoms in a conductor because of the momentum transfer from moving electrons under high current densities. It causes physical degradation in microelectronic circuit, i.e., atoms displaced by the ‘electron wind’ build up to form short-circuiting ‘hillocks’ and leave behind empty ‘voids’ which result in open circuits.
Electrometer tube – It is an electronic tube, with very high grid-to-cathode resistance which is suitable for use with input grid resistors of very high ohmic value.
Electrometric titration – It consists of a family of techniques in which the location of the endpoint of a titration involves the measurement of, or observation of changes in, some electrical quantity. Examples of such quantities include potential, current, conductance, frequency, and phase.
Electromobility – It is also called e-mobility. It is the transition from internal combustion engines to electric propulsion in transportation. It is a multi-disciplinary field, encompassing automotive, electrical, and systems engineering, which designs and optimizes electric vehicles (EVs), powertrains, battery management systems, and charging infrastructure.
Electro-motive force – It is the force which determines the flow of electricity. It is a difference of electric potential. In electromagnetism and electronics, electromotive force is an energy transfer to an electric circuit per unit of electric charge, measured in volts. Devices called electrical transducers provide an emf by converting other forms of energy into electrical energy.
Electro-motive force series (emf series) – It is a series of elements arranged according to their standard electrode potentials, with ‘noble’ metals such as gold being positive and ‘active’ metals such as zinc being negative. In corrosion studies, the analogous but more practical galvanic series of metals is normally used. The relative positions of a given metal are not necessarily the same in the two series.
Electro-motive force source – It is a device which converts non-electrical energy into electrical energy, providing the potential difference (voltage or push) needed to drive electric current through a circuit. Examples include batteries, generators, solar cells, and transformers.
Electron – It is a very small negatively charged particle which orbits the nucleus of an atom, and can also exist in a free state for short periods of time.
Electron acceptor – It is a chemical entity or material which receives electrons during an oxidation-reduction (redox) reaction, becoming reduced in the process. This concept spans multiple disciplines, operating differently depending on the specific field.
Electron backscatter diffraction – It is a ‘scanning electron microscope (SEM)-based technique used to analyze the crystallographic structure, orientation, and phase distribution of crystalline materials at the micrometer or nano-meter scale. It works by analyzing diffraction patterns (Kikuchi patterns) formed by backscattered electrons on a tilted sample, providing detailed microstructural data such as grain size, boundary character, and texture. Electron backscatter diffraction (EBSD) technique is frequently paired with ‘energy-dispersive X-ray spectroscopy’ (EDS) to provide simultaneous chemical and crystallographic information.
Electron bands – It is the energy states for the free electrons in a metal, as described by the use of the band theory (zone theory) of electron structure. It is also called Brillouin zones.
Electron beam – It is a stream of electrons in an electron-optical system.
Electron bombardment – It is the process of directing a concentrated, high-velocity stream of electrons at a target material. The immense kinetic energy of these electrons converts into intense heat or ionization upon impact, driving critical manufacturing, analytical, and propulsion processes.
Electron-bombardment thrusters – It is a type of electric propulsion (or ion thruster) used in spacecraft. Electrons bombard a propellant gas (such as xenon) to strip away its electrons, creating a high-energy plasma that is accelerated electromagnetically to generate thrust.
Electron-beam curing – It is a system for curing paint films using the energy of an electron beam. The process lends itself to high-speed curing of paint on flat surfaces. Special paints are to be used and personal shielding is needed.
Electron beam cutting – It is a cutting process which uses the heat got from a concentrated beam composed mainly of high-velocity electrons, which impinge on the work-pieces to be cut, it may or may not use an externally supplied gas.
Electron-beam evaporation – It is utilized in thin-film deposition and semi-conductor manufacturing. This method directs electron beams to bombard a target material. The target rapidly vapourizes and condenses onto a substrate to form highly dense coatings.
Electron beam gun – It is a device for producing and accelerating electrons. Typical components include the emitter (also called the filament or cathode), which is heated to produce electrons through thermionic emission, a cup (also called the grid or grid cup), and the anode.
Electron beam hardening – It is a precise surface treatment process which uses a focused beam of high-energy electrons to rapidly heat the surface layer of a material, typically steel or iron, to its austenitization temperature, followed by immediate self-quenching. This creates a hardened martensitic structure which boosts wear resistance while preserving the component’s ductile core.
Electron beam hardening treatment – It is a short surface hardening procedure for martensitically hardenable ferrous materials. Austenitizing occurs through the energy transferred by electron beams. Precise application of the energy with respect to workpiece location and elapsed time using a focused and deflectable electron beam makes it the process of choice, especially for the partial hardening of highly stressed surface regions in components. The austenitizing process advances from the surface toward the inner core regions of the component through heat conduction, hence allowing for a defined adjustment of the hardness penetration by selecting a suitable energy transfer duration. Typical hardening depths got by this process range from 0.1 millimeters to 1.5 millimeters. The rapid cooling of the austenite needed for martensite formation occurs through a self-quenching process which is dependent on the thermal conductivity and starts after the energy transfer has ceased. Depending on the material selected, the workpiece thickness required should be at least 5 times to 10 times the austenitizing depth.
Electron beam heat treating – It is a selective surface hardening process which rapidly heats a surface by direct bombardment with an accelerated stream of electrons.
Electron beam heating-quenching – It is a high-precision surface hardening process which uses a focused beam of high-energy electrons to rapidly heat a metal surface to austenitic temperatures in a vacuum, followed by immediate ‘self-quenching’ through heat conduction into the cold bulk material. This creates a hard, wear-resistant martensite layer without distortion.
Electron beam machining – It is removing material by melting and vaporizing the work-piece at the point of impingement of a focused high-velocity beam of electrons. The machining is done in high vacuum to eliminate scattering of the electrons due to interaction with gas molecules. The most important use of electron beam machining is for hole drilling.
Electron beam melting – It is a 3-dimention (3D) manufacturing process in which a powdered metal is melted by a high-energy beam of electrons. An electron beam produces a stream of electrons that is guided by a magnetic field, melting layer upon layer of powdered metal to create an object matching the precise specifications defined by a computer aided design model. Production takes place in a vacuum chamber to guard against oxidation that can compromise highly reactive materials.
Electron-beam physical vapour deposition – It is a high-vacuum coating technique where a high-energy electron beam bombards a target material, causing it to melt and evaporate. The vapourized atoms travel and condense onto a substrate, creating a high-purity, thin, and frequently dendritic-structured film.
Electron beam probe – It is a highly focused stream of electrons used for the non-destructive analysis, testing, or modification of materials. It directs a concentrated flow of high-velocity electrons onto a target, measuring the resulting signals to evaluate chemical composition, electrical properties, or structural integrity at micro-scale and nano-scale levels.
Electron-beam radiation – It is the radiation generated from high-energy electrons which is used in cross-linking coating systems.
Electron-beam refining – It is a high-vacuum metallurgical process which uses high-energy electron beams to melt and purify reactive or refractory metals (such as titanium, T=tantalum, niobium, and tungsten) by evaporating impurities and removing inclusions. It produces ultra-pure metals by controlling material vapourization and degassing in a water-cooled copper crucible.
Electron-beam remelting – It is a specialized vacuum metallurgy process used to produce high-purity ingots of reactive and refractory metals. It uses a high-energy electron beam to melt feedstock (such as raw material or cast electrodes) in a high-vacuum chamber, allowing impurities to evaporate and the material to be purified in a water-cooled, ceramic-free crucible.
Electron beam technology – It is a high-energy process which directs concentrated streams of accelerated electrons onto materials. This kinetic energy is harnessed to either generate intense localized heat (for manufacturing) or alter molecular structures (for processing) with extreme precision.
Electron beam welding – It is a welding process which produces coalescence of metals with the heat got from a concentrated beam composed primarily of high-velocity electrons impinging on the surfaces to be joined.
Electron binding energy – It is the minimum energy rneeded to remove an electron from an atom within a metal or alloy, overcoming the electrostatic attraction of the nucleus. It determines electronic stability and is measured in electron-volts (eV), with inner shell electrons having higher binding energy than valence electrons.
Electron capture – It is a process where analytes with high electron affinity capture electrons from a steady stream emitted in an electron capture detector, resulting in a reduction of current which produces a signal corresponding to the presence of these analytes.
Electron channel – It is a conductive pathway formed in a transistor, such as metal-oxide semi-conductor field-effect transistor (MOSFET), which allows electric current to flow between the source and drain terminals. It is created or modulated by an applied electrical gate voltage.
Electron collector – It is an electrode designed to capture, absorb, and dissipate beams or streams of electrons after they have served their purpose in a device. It is a critical component of the air cathode which provides the foundation for the gas diffusion and catalytic layers, needing high conductivity, corrosion resistance, and physical strength. It can be made from materials such as carbon-based substances or metallic options, with the latter offering advantages in conductivity and durability.
Electron concentration – It refers to the density of electrons present in a material, such as InN (indium nitride) nano-wires, which considerably influences the electrical conduction properties of the material.
Electron configuration – It is the distribution of electrons within an atom’s orbitals, shells, and subshells, determining the element’s unique chemical and physical properties. It defines metallic bonding, alloy formation, and oxidation states by describing how valence electrons occupy orbitals (e.g., 1s, 2p, 3d) following Aufbau principle, Pauli exclusion principle, and Hund’s rule.
Electron confinement – It is the restriction of an electron’s movement into a small, defined space. When electrons are trapped in tiny, nano-scale dimensions, their energy states change from a continuous band to discrete, atom-like levels, altering the material’s optical and electrical properties. This phenomenon drives how quantum dots, light-emitting diodes (LEDs), and advanced transistors behave.
Electron devices – These are hardware components or systems which control, process, and manage the flow of electric current (electrons) to perform specific tasks. They rely on active components, such as semi-conductors, transistors, and diodes, to manipulate electron flow for signal processing, computing, data storage, and automation.
Electron diffraction – It is the phenomenon, or the technique of producing diffraction patterns through the incidence of electrons upon matter.
Electron diffusion – It is the random, thermal movement of electrons from regions of high concentration to regions of low concentration within a material (such as a semi-conductor). Driven by concentration gradients rather than electric fields, it works to establish a uniform distribution of charge.
Electron diffusion length – It is the average distance an electron can travel through a material, such as a semi-conductor, from its point of creation or injection until it recombines with another charge carrier.
Electron distribution function – It is a mathematical probability function which describes the spatial location, velocity, or energy state of electrons within a system. It tracks the statistical likelihood of finding an electron in specific conditions, accounting for their behaviour in atoms, molecules, or larger systems like plasma.
Electron donor – It is a chemical entity or atom which transfers electrons to another compound. By giving up electrons, it acts as a reducing agent and becomes oxidized. This concept is fundamental to multiple scientific disciplines.
Electron effect – It normally refers to how the distribution of electron density within a molecule influences its stability, structure, and chemical reactivity. It can also refer to the interactions of multiple electrons, or the emission of electrons caused by external stimuli like light.
Electron effective mass – It is the apparent mass which an electron shows when moving inside a crystal lattice. It allows the complex interactions between the electron and the periodic potential of the atoms to be treated as if it has been a normal free particle, but with an altered mass.
Electro-negative element – It is an atom with a high tendency to attract or gain shared electrons in a chemical bond, frequently forming negative ions (anions). These elements, typically non-metals found on the right side of the periodic table, increase in strength from left to right and decrease down a group, with Fluorine (F) being the most electro-negative. Highly electro-negative elements are fluorine (F), oxygen (O), nitrogen (N), and chlorine (Cl).
Electro-negativity – It is the relative tendency of an atom to attract electrons. Carbon, the basic building block of polymers, is neutral in this respect with a Pauling electro-negativity of 2.5. Metallic atoms on the left side of the periodic table have a propensity to lose electrons when forming covalent bonds, and their electro-negativities are less than 2.5. The atoms on the right side of the periodic table tend to gain electrons, and their electro-negativities tend to be higher than 2.5.
Electro-negativity difference – It refers to the variation in electro-negativity between two bonded atoms, influencing the character of the chemical bond. It can be quantified using formulas related to dissociation energies, reflecting the ability of each atom to attract electron charge.
Electron emission – It is the release of electrons from the surface of a material (typically a metal). It occurs when external energy provides free electrons with enough kinetic energy to overcome the attractive forces holding them to the material’s surface. For releasing an electron, the energy supplied is required to meet or exceed the material’s work function. The work function represents the minimum energy needed for an electron to escape the surface barrier of the material and is typically measured in electron-volts (eV).
Electron energy – It refers to the energy which electrons possess within a solid, which is influenced by their interactions within the crystal lattice and is characterized by a distribution in accordance with Fermi-Dirac statistics. The energy of electrons in metals is bounded by the Fermi energy level, with free electrons contributing to electrical conductivity.
Electron energy band – It is a continuous range of allowed energy levels which electrons can occupy in a solid, formed by the merging of discrete atomic energy levels because of the close proximity of atoms. These bands determine a material’s electrical conductivity by classifying energy states into valence, conduction, and forbidden gaps.
Electron energy level – It refers to the specific, quantized quantities of energy which electrons can possess while orbiting an atom’s nucleus. Electrons cannot exist between these levels. They occupy exact, allowable ‘steps’ (like standing on a staircase).
Electron energy loss spectroscopy – It is a spectrographic technique in the electron microscope which analyzes the energy distribution of the electrons transmitted through the sample. The energy loss spectrum is characteristic of the chemical composition of the region being sampled.
Electro-neutrality – It is the principle which the sum of all positive charges in a solution is required to equal the sum of all negative charges, ensuring that macroscopic charge separation is not possible in electrolytic solutions.
Electron flow – It is a movement of electrons in an external circuit an anode and cathode in a corrosion cell. The current flow is arbitrarily considered to be in an opposite direction to the electron flow.
Electron gun – It is a device for producing and accelerating a beam of electrons.
Electron hole – It is a quasiparticle denoting the lack of an electron at a position where one can exist in an atom or atomic lattice. Since in a normal atom or crystal lattice the negative charge of the electrons is balanced by the positive charge of the atomic nuclei, the absence of an electron leaves a net positive charge at the hole’s location.
Electron-hole pair formation – It is the process where external energy (like heat or light) excites an electron from a material’s valence band into its higher-energy conduction band. This jump creates a free, mobile electron while leaving behind a positively charged vacancy called a ‘hole’ in the valence band. This fundamental concept in semi-conductor drives the operation of opto-electronic devices, such as solar cells, photo-diodes, and transistors
Electronic access control and monitoring system – It is a technology-driven security solution which regulates, permits, or denies entry to physical spaces (doors, gates, facilities) by authenticating credentials, such as cards, PINs (personal identification numbers), or biometrics, while recording real-time entry and exit data. It provides modern, flexible, and centralized security over traditional keys, enabling remote management, audit trails, and, in some cases, integration with surveillance systems for improved site safety.
Electronically scanned array – It is a computer-controlled antenna array which steers beams of radio waves electronically without physically moving the antenna. By dynamically altering the phase and amplitude of signals across multiple radiating elements, Electronically scanned arrays (ESAs) provide near-instantaneous beam steering, multi-target tracking, and high resilience to hardware failures.
Electronic amplifier – It is a device which increases the power of an electrical signal by electronic means.
Electronic blow-energy control – It is a method which uses solid-state electronics and sensors to precisely manage the power, force, or intensity of a percussive or pneumatic tool’s ‘blow’ or impact. This system allows operators or automated controllers to adjust the energy output of machinery (such as breakers, hammers, or piezo-actuators) in real-time for improved efficiency, accuracy, and safety.
Electronic charge density – It is the quantity of electric charge per unit length, surface area, or volume. In electrical engineering and electromagnetics, it mathematically describes how charge is distributed across a region. In materials and quantum engineering, it refers to the spatial distribution of electrons, which dictates the electronic structure and properties of materials.
Electronic chart – It is a digitized representation of a nautical paper chart. From an engineering standpoint, it is a core ‘geographic information system’ (GIS) sub-subsystem which integrates digital databases with real-time navigational sensors to automate route planning and monitoring for safe maritime operations.
Electronic circuit – It is a circuit using one or more electronic devices.
Electronic circuit breaker – It is a solid-state protective device which interrupts power when current exceeds a predetermined threshold. Unlike mechanical breakers, electronic circuit breakers (ECBs) use active electronic components, like MOSFETs (metal-oxide semiconductor field-effect transistor) or silicon-controlled rectifiers (SCRs), and high-speed feedback loops to provide near-instantaneous overcurrent protection with no moving parts
Electronic circuitry – It refers to the arrangement of electronic components and connections which facilitate the functioning of electrical devices, frequently represented through specific diagrams created using computer-aided design (CAD) tools. These tools support the modeling and simulation of circuit behaviour, enabling engineers to investigate and optimize their designs.
Electronic circuit tracking – It consist of a ‘maximum power point tracking (MPPT) circuit, or, is a system which optimizes the power output from solar panels by continuously adjusting the electrical operating point to extract the maximum available power. It monitors input voltage and current to ensure the photo-voltaic arrays operate at their maximum power point.
Electronic command – It is a digital or electronic instruction transmitted to a device, software, or system to trigger a specific action or operation. It typically consists of a coded signal (like a binary string or data packet) sent from a controller to a receiver.
Electronic commerce – It is also called e-commerce. It is the buying and selling of goods, services, or information over computer networks, mainly the internet. It involves online transactions through websites, mobile apps, and social media, covering B2B (business-to-business), B2C (business-to-customer), C2B (customer to business), and C2C (customer to customer) models. Key elements include digital payments, online shopping carts, and electronic data interchange.
Electronic component – It is an active or passive element of an electronic circuit.
Electronic conductivity – It consists of the movement of charge, specifically electrons or holes, in response to an electric field within solid conductors such as metals and semi-conductors.
Electronic contribution – It refers to the impact or role of electronic circuits, components, and systems in controlling, processing, or transmitting electricity and information. It involves manipulating the flow of electrons using active semiconductor devices (like transistors) to amplify signals, process data, or perform logical operations.
Electronic control – It is the process of using electronic circuits and systems to manage, command, and regulate the behaviour of machines or processes. It involves a continuous loop of monitoring physical conditions, processing that data, and directing physical actions to achieve a desired performance.
Electronic control module – It is also known as an electronic control unit (ECU). It is an embedded minicomputer which manages one or more electrical systems or sub-systems in a vehicle or industrial equipment. It acts as the vehicle’s ‘brain’ by processing sensor inputs in real-time to optimize efficiency, performance, and emissions.
Electronic control unit – In some equipments, it is an embedded electronic system which controls certain aspects of equipment operation.
Electronic counter-measures – These are engineering systems designed to deceive or disrupt enemy electronic emissions, mainly in radar, sonar, and communications. In engineering, it involves applying advanced radio frequency (RF) and signal processing to mask friendly assets or spoof enemy sensors.
Electronic data – It is information stored, processed, or transmitted by computer systems, including programmes, software, coded instructions, and digitized documents. It facilitates automated, paperless, and secure exchange of information between systems, frequently used for organizational transactions, data analysis, and storage.
Electronic data capture (EDC) system – It is a computerized, software-based solution designed to collect, manage, and store clinical trial data in an electronic format, replacing traditional paper-based methods. It uses electronic case report forms to streamline data entry, improve accuracy, ensure regulatory compliance, and accelerate study timelines.
Electronic data interchange – It refers to the automated exchange of business documents between organizations using standardized electronic formats, instead of paper or manual methods. This includes documents like purchase orders, invoices, and shipping notices, facilitating quicker and more efficient communication and data transfer. In simpler terms, electronic data interchange is a way for businesses to send and receive documents electronically, speeding up processes and reducing errors.
Electronic document identification systems – These systems refer to digital solutions which authenticate, track, and verify both the origin of digital documents and the identity of the individuals or organizations accessing them. In engineering, these systems are critical for managing complex assets, controlling revisions, and ensuring regulatory compliance.
Electronic design – It is the process of conceptualizing, creating, and optimizing electronic circuits and systems. It blends hardware, software, and physical layout, ensuring that devices, from microchips to telecommunications networks, meet specific performance, power, and cost constraints. Electronic design engineering follows a highly iterative lifecycle which transitions a concept into a functional, manufacturable product.
Electronic design automation – It is also referred to as electronic computer-aided design (ECAD). It is a category of software tools for designing electronic systems such as integrated circuits and printed circuit boards.
Electronic engineering – It is a sub-discipline of electrical engineering which focuses on the design, development, and application of circuits, devices, and systems which use active electronic components (like semi-conductors and transistors) to control, process, and amplify electric current and signals.
Electronic excitation – It is a quantum process where an electron absorbs energy and transitions from its stable ground state to a higher, less stable energy level or orbital. It is foundational for semi-conductor function, opto-electronics, lasers, and chemical bonding.
Electronic filter – It is a filter which alters some frequency-related characteristic of a signal.
Electronic identification (eID) frameworks – These are standardized, socio-technical systems which securely link a physical identity to digital credentials, allowing individuals and organizations to authenticate themselves online. Engineering these frameworks involves building the cryptographic infrastructure, identity proofing, and verification protocols necessary for seamless and legally recognized transactions.
Electronic interface – It defines the physical and logical boundaries where two or more electrical or electronic systems connect to communicate, transfer power, or exchange data. It acts as a bridge, translating disparate signals so separate components can function together seamlessly.
Electronic line – It normally refers to a conductor or pathway which carries signals. Signal lines are copper traces on a printed circuit board (PCB) or wires in a cable which carry information-bearing electrical signals. Transmission lines are specialized interconnects, like coaxial cables or parallel PCB (printed circuit board) traces, where the travel time of the electrical wave matters. In this domain, the line is defined by its characteristic impedance, which is required to match the source and load to prevent signal reflection.
Electronic load cell – It is a precision electro-mechanical transducer which converts mechanical force (such as weight, tension, compression, or torque) into a proportional, readable electrical signal. It serves as the hidden ‘brain’ in modern digital weighing scales, industrial process controls, and structural safety monitors.
Electronic mail – It is also called email. It is a digital communication method which uses computer networks, mainly the internet, to send, receive, and store messages between devices instantly. It allows users to exchange text, documents, images, and audio files globally. Messages are managed through email clients (e.g., Outlook) or web-based services (e.g., Gmail).
Electronic messaging services – These are digital platforms or systems, such as email, instant messaging, and SMS (short message service), which facilitate the near real-time transmission of text, audio, images, or video over communication networks. These services act as intermediaries, enabling fast, recordable communication between individuals or automated systems.
Electronic module – It is a self-contained, modular assembly of electronic components designed to perform a specific function within a larger system. It integrates parts like integrated circuits, sensors, and resistors on a printed circuit board (PCB), allowing engineers to reuse designs and simplify complex hardware development.
Electronic noise – It is any unwanted random fluctuation or disturbance in an electrical signal which corrupts the desired information. It degrades signal clarity, limits system sensitivity, and is typically measured by metrics like the signal-to-noise ratio (SNR).
Electronic optical circuit board – It is a hybrid substrate which integrates both traditional electrical copper traces and optical waveguides (normally made of polymer or glass) onto a single board. It routes power and low-speed signals electrically, while utilizing light for high-speed, high-bandwidth data transmission.
Electronic packaging – It is the design and manufacturing of enclosures, housings, and interconnections for electronic devices. It bridges the gap between raw micro-chips and functional consumer products, providing physical protection against damage, efficient heat dissipation, and safe electrical connections.
Electronic product code – It is a unique identifier stored on an RFID (radio frequency identification) tag, designed to track physical objects like products, cases, or pallets within a supply chain. It serves as a modern successor to barcodes, providing granular, real-time inventory visibility without needing line-of-sight scanning.
Electronics – It is the study of the flow of electrons through a vacuum, gases, or semi-conductors.
Electronics engineering – It is a sub-discipline of electrical engineering which focuses on the design, development, and testing of circuits, semiconductor devices, and micro-processors. It powers the digital world, building everything from smartphones to satellite systems by managing the flow of electricity to amplify and process signals.
Electronics industry – It is the economic sector which designs, develops, manufactures, and markets electronic components, devices, and systems. Electronic engineering is the branch of engineering which powers this sector, dealing with the design, fabrication, and operation of circuits and micro-processors which make modern technology possible.
Electronic polarizability – It is the tendency of an atom’s electron cloud to distort and shift away from its central, positively charged nucleus in response to an external electric field. This creates an induced electric dipole moment within the atom.
Electronic polymer – It is frequently called a conductive or electroactive polymer. It is a class of synthetic macro-molecule which shows electrical conductivity, semi-conductivity, or changes in shape in response to an electric field. Unlike conventional insulating plastics, these polymers combine the unique mechanical properties of plastics with electronic capabilities.
Electronic power circuit – It is a specialized electronic circuit designed to process, control, and convert electrical energy. It operates at higher voltages and currents than standard signal circuits, efficiently transforming raw power from a source, like an AC (alternating current) grid or battery, into a usable format for motors, computers, or appliances. These circuits are the backbone of modern energy conversion. Instead of continuously dissipating energy like a resistor, they achieve high efficiency by using semiconductor devices as high-speed switches.
Electronics – It is the branch of science and engineering which deals with the emission, behaviour, and control of electrons using specialized devices. It involves manipulating electric currents through active components (like transistors, diodes, and microchips) to process data, transmit information, and perform complex tasks. The field is broadly divided into several key concepts.
Electronic scanning – It is a method of deflecting a beam or signal across a field of view using electrical controls rather than mechanical movement. It is mainly used to rapidly steer radar / antenna beams or to map surfaces using an electron beam.
Electronic scanning antenna – It is frequently called a phased array. It is a computer-controlled antenna array which steers a beam of radio waves without physically moving the hardware. It manipulates the phase or frequency of the signal at each element to rapidly and precisely redirect energy in space.
Electronic sources – It refer to a range of digital materials used for information gathering, including online digital libraries, technical reports, books, patents, and relevant online literature.
Electronic speckle pattern interferometry – It is also called digital speckle interferometry. It is a non-contact, high-accuracy optical technique used to measure surface displacements and deformation on rough objects. It uses a laser, a camera, and digital image processing to detect sub-wave-length movements caused by stress, vibration, or thermal loading, producing real-time ‘fringe’ data.
Electronic specific heat coefficient – It is frequently denoted as ‘gamma’ and known as the Sommerfeld coefficient. It is the constant of proportionality relating the linear temperature dependence of a metal’s electronic heat capacity (Ce) to the temperature (T) at low temperatures, defined by the relationship ‘Ce = gamma x T’. It measures the heat energy absorbed by the conduction electron gas in a solid as the temperature increases.
Electronic speed control – It is a device for regulating the speed of a motor.
Electronic spreadsheet – It is a digital software tool which organizes data into a grid of intersecting rows and columns. It is an important computational asset used for numerical modelling, project management, and automated design calculations, functioning as an interactive, computerized ledger.
Electronics thermal management – It is the engineering discipline of controlling, dissipating, and regulating the heat generated by electronic devices. Its main goal is to maintain component temperatures within safe operating limits, preventing performance degradation, hardware failure, and thermal runaway. The field relies on three fundamental modes of heat transfer.
Electronic textiles – These are also called e-textiles. These are fabrics which seamlessly integrate electronic components, such as sensors, micro-controllers, and batteries, into their structure. They function electrically as circuits while behaving physically as flexible, comfortable cloth. This field merges materials science, electrical engineering, and textile manufacturing.
Electronic theory – It is the concept which electrostatic forces between an adhesive and adherend are responsible for adhesion, with electrostatic attraction forming an electrical double layer at their interface, which provides resistance to separation.
Electronic valves – In these valves, the movement of the ball or flap which controls the flow is controlled electronically through circuits or digitally. These types of valves have very precise control but can also be very expensive.
Electronic zero strain logic – It is a sophisticated electronic control system designed for zero pressure accumulation conveyor systems, necessitating recurrent evaluations to ensure continued functionality and optimal system performance’
Electron image – It is a representation of an object formed by a beam of electrons focused by an electron-optical system.
Electron injection – It is the fundamental process of introducing electrons into a material, semiconductor junction, or device structure to facilitate electrical conductivity, light emission, or data storage. This concept applies to several major branches of physics and engineering such as optoelectronics (light emitting diodes and solar cells), semi-conductor physics and p-n Junctions, and integrated circuits and memory (hot electron injection).
Electron ionization – It is a hard ionization technique used in mass spectrometry where high-energy electrons (typically 70 electron volts) bombard gaseous sample molecules, causing them to ionize and fragment extensively. It produces characteristic fragmentation patterns (fingerprints) for identifying unknown volatile compounds and is widely used for analyzing gases, residues, and surface contaminants.
Electron lens – It is a device for focusing an electron beam to produce an image of an object.
Electron level – It is a specific, quantized region surrounding an atomic nucleus where electrons reside. Electrons are restricted to these discrete levels, meaning they cannot exist in the spaces between them.
Electron lifetime – It is the duration in which conduction band electrons remain in their excited state before recombining, which can vary based on factors such as light intensity and the presence of charge traps within the material. It means the fundamental stability of the electron itself.
Electron micrograph – It is a reproduction of an image formed by the action of an electron beam on a photographic emulsion.
Electron microprobe analyzer – It is also called electron probe micro-analyzer. It is a non-destructive, high-precision analytical tool which uses a focused electron beam to determine the quantitative elemental composition (from boron to uranium / plutonium) of small volumes in solid materials. It is an instrument for selective analysis of a microscopic area, in which an electron beam bombards the point of interest in vacuum at a given energy level. Intensity of backscatter is measured to interpret which chemical elements are present, and by scanning a large area the microprobe can analyze chemical composition and indicate the distribution of an element.
Electron microscope – it is an electron-optical device that produces a magnified image of an object. Detail can be revealed by selective transmission, reflection, or emission of electrons by the object. It is a microscope which uses a beam of electrons as a source of illumination. They use electron optics which are analogous to the glass lenses of an optical light microscope to control the electron beam, e.g., focusing them to produce magnified images or electron diffraction patterns. As the wavelength of an electron can be up to 100,000 times smaller than that of visible light, electron microscopes have a much higher resolution of about 0.1 nano-meter, which compares to around 200 nano-meters for light microscopes.
Electron microscope column – It is the assembly of gun, lenses, sample, and viewing and plate chambers.
Electron microscopy -It is the study of materials by means of an electron microscope.
Electron microscopy impression – It is the reproduction of the surface contours of a sample formed in a plastic material after the application of pressure, heat, or both.
Electron multiplier phototube – It is a device in which incident electro-magnetic radiation creates electrons by the photoelectric effect. These electrons are accelerated by a series of electrodes called dynodes, with secondary emission adding electrons to the stream at each dynode. It is also known as multiplier phototube, photoelectric electron-multiplier tube, and photo-multiplier tube.
Electron number – It refers to the total number of electrons associated with an atom, ion, or molecule. It dictates the chemical properties, reactivity, and bonding behavior of an element. In neutral atoms, the electron number is equal to the atomic number (number of protons). Ions are formed when atoms lose or gain electrons. In cations (positive charge), the electron number is the atomic number minus the net charge. In anions (negative charge), the electron number is the atomic number plus the net charge.
Electron optical axis – It is the path of an electron through an electron-optical system, along which it suffers no deflection due to lens fields. This axis does not necessarily coincide with the mechanical axis of the system.
Electron optical lithography – it is frequently referred to as electron beam lithography (EBL). It is a nano-fabrication technique which uses a focused beam of electrons to draw custom patterns directly onto a substrate coated with an electron-sensitive film (resist). Since it bypasses the need for physical photomasks, it is known as a ‘maskless’ technique.
Electron optical system – It is a combination of parts capable of producing and controlling a beam of electrons to yield an image of an object.
Electron pathway – It describes the physical or logical route electric charges (electrons) follow. By convention, current flows from positive to negative. However, the actual physical pathway of electrons goes from the negative terminal (excess of electrons) to the positive terminal (deficiency of electrons).In case of circuit path, the pathway forms a continuous, closed loop (circuit) for electrons to move and power devices.
Electron probe – It is a narrow beam of electrons which is used to scan or illuminate an object or screen.
Electron probe micro-analyzer – It is a microbeam instrument used mainly for the in situ non-destructive chemical analysis of minute solid samples. It also informally called an electron microprobe, or just probe. The main importance of an electron probe micro-analyzer is the ability to acquire precise, quantitative elemental analyses at very small ‘spot’ sizes (as little as 1micrometer to 2 micrometers). The electron microprobe operates under the principle that if a solid material is bombarded by an accelerated and focused electron beam, the incident electron beam has sufficient energy to liberate both matter and energy from the sample. These electron-sample interactions mainly liberate heat, but they also yield both derivative electrons and X-rays.
Electron probe x-ray micro-analysis – It is a technique in analytical chemistry in which a finely focused beam of electrons is used to excite an x-ray spectrum characteristic of the elements in a small region of the sample.
Electron scattering – It is a change in the direction of propagation or kinetic energy of an electron as a result of a collision.
Electron spectroscopy – It refers to a group of surface-sensitive analytical techniques, mainly X-ray photo-electron spectroscopy / electron spectroscopy for chemical analysis (XPS / ESCA) and Auger electron spectroscopy (AES), used to identify elements and chemical states on the topmost atomic layers (typically below 10 nano-meters) of metals, alloys, and coatings. These methods measure the kinetic energy of electrons ejected from a material, identifying surface composition, contamination, oxidation, and corrosion.
Electron spectroscopy for chemical analysis – It is normally known as X-ray photo-electron spectroscopy (XPS). It is a surface-sensitive analytical technique used in metallurgy to identify elemental composition and oxidation states in the top 1 nano-meter to 10 nano-meters of materials. It works by irradiating a surface with X-rays, causing the emission of photo-electrons whose kinetic energies are measured to determine elemental binding energies.
Electron spin resonance (ESR) – it is also known as electron paramagnetic resonance (EPR) and paramagnetic resonance. It is an instrumental technique which can provide a great deal of information on any material containing unpaired electrons. Such materials are ordinarily paramagnetic, although they can sometimes be ordered magnetic solids, such as ferro-magnets. If placed in a microwave-resonant cavity between the pole pieces of a strong electro-magnet, such a sample absorbs microwave energy at particular values of the magnetic field which are characteristic of the positions and the crystalline environments of the unpaired electrons. Plotting the microwave absorption intensity against the magnetic-field strength yields a line spectrum. The number, positions, intensities, and shapes of the component lines provide information used to identify and specify such components and properties of the sample as the degree of crystallinity, valence states of ions, local crystalline environments, defects and trace transition ions, radiation products, and free radicals.
Electron state – It is a complete description of an electron’s properties and behaviour within a system, such as an atom or a crystal. Since electrons are quantum particles, they do not have a specific location or path. Instead, their state is defined by a mathematical wave-function which determines the probability of finding them in a certain region.
Electron state level – It is a specific, quantized, and allowable energy value an electron can occupy within an atom, molecule, or solid. Electrons cannot exist between these discrete levels, which are defined by quantum numbers and typically represent specific orbitals.
Electron system – It is an assembly of two or more interacting electrons within a defined boundary (such as an atom, molecule, or crystal lattice). It operates as a complex, collective many-body quantum mechanical environment where particle behaviours dictate the chemical, physical, and electrical properties of the material. The concept spans several scientific disciplines.
Electron temperature – It is the measure of the average kinetic energy of electrons in a plasma, which influences factors such as the scaled inverse screening length and the behaviour of ions within the plasma.
Electron trajectory – It is the path of an electron.
Electron transition – It is the process by which an electron moves between energy levels within an atom, either gaining energy to ascend to a higher state or releasing energy to descend to a lower state. This process frequently involves the emission or absorption of photons corresponding to the energy difference between the two states.
Electron trap – It is a defect, impurity, or localized potential well within a material which captures and holds an electron, restricting its movement. These traps prevent electrons from recombining with ‘holes’ and are fundamental to understanding luminescence, photo-conductivity, and the reliability of electronic devices.
Electron vacancy number – It is frequently referred to as the average electron vacancy number or Nv number. It is a computed parameter used to predict the stability of the austenitic matrix (gamma phase) in nickel-base and cobalt-base superalloys. It measures the tendency of an alloy to form brittle ‘topologically close-packed’ (TCP) phases, such as sigma, mu, or Laves phases, which can embrittle the material at high temperatures.
Electron velocity – It is the rate of motion of an electron. It is the speed at which electrons move through a semi-conductor material under the influence of an electric field, with peak electron velocity representing the maximum achievable speed in high-frequency operations. This velocity can be estimated through pulsed current measurements in semiconductor structures, indicating how it changes with varying electric fields.
Electron volt (eV) – It is a tiny unit of energy defined as the quantity of kinetic energy gained (or lost) by a single unbound electron as it accelerates through an electrostatic potential difference of one volt (1 V) in a vacuum. It is mainly used in atomic, nuclear, and particle physics since it offers a convenient scale for measuring the minute energies involved.
Electron wave-length It is the wave-length necessary to account for the deviation of electron rays in crystals by wave diffraction theory. It is numerically equal to the quotient of Planck’s constant divided by the electron momentum.
Electron wind effect – It is the momentum transferred from flowing conduction electrons to the atoms or crystalline defects in a metal. When a high-density electric current passes through a conductor, the moving electrons physically collide with metal ions, ‘pushing’ them in the direction of the electron flow.
Electron wind force – It is the mechanical force exerted on an atomic lattice by a high-density flow of drifting electrons. When electrons accelerate through a conductor, they transfer momentum to atoms or defects through scattering, effectively ‘pushing’ them in the direction of the current.
Electro-optical device – It is a component or system which interacts with, manipulates, or generates light using electrical signals. By leveraging materials whose optical properties change in response to an electric field, these devices form the bridge between electronic controls and optical communications, imaging, or sensor systems.
Electro-optics – It is a branch of engineering which studies and applies the interaction between electrical energy and optical phenomena. It mainly deals with how electric fields alter the optical properties of materials (such as their refractive index), enabling precise control over light waves.
Electro-osmotic dewatering – It is a non-thermal process which uses an applied electric field (direct current) to drive moisture through a porous material or charged medium. It effectively extracts trapped and adsorbed water which is too tightly bound to be removed by conventional mechanical methods like pressing or centrifugation.
Electro-osmotic flow – It is the bulk movement of liquid in a micro-channel induced by the migration of mobile counter ions towards an oppositely charged electrode when an electric field is applied to charged surfaces. Electro-osmotic flow (EOF) is utilized for fluid actuation in micro-scale systems but needs the presence of charged surfaces.
Electro-oxidation – It is an electro-chemical process where an electric current is used to drive an oxidation reaction. Normally applied in wastewater treatment, it converts toxic organic pollutants into harmless by-products by transferring electrons at the surface of an anode or generating powerful oxidizing agents (like hydroxyl radicals).
Electrophoresis – It is the transport of charged colloidal or macro-molecular materials in an electric field.
Electrophoresis technique – It is a laboratory technique used to separate charged molecules by applying an electric current. It forces these molecules to migrate through a porous gel or matrix, which acts as a molecular sieve, sorting them by their size and electrical charge.
Electrophoretic display – It is normally known as an e-paper or electronic ink display. It is a reflective screen technology which mimics the appearance of natural ink on paper. It creates images by using an electric field to move microscopic, charged pigment particles suspended within a clear fluid. The technology relies on a principle called electrophoresis, the motion of charged particles in a fluid under an applied electric force.
Electrophoretic mobility – It is the measurement of how fast a charged particle or molecule moves through a fluid when subjected to an external electric field. It serves as a fundamental metric to determine a particle’s surface charge and molecular size. It is calculated as the ratio of a particle’s migration velocity to the applied electric field strength.
Electrophoretic paint – It is also called e-coat. It is a paint which is applied by electrophoresis, in which colloidal charged particles are transported within an electric field.
Electrophoretic technology – It uses an applied electric field to manipulate charged particles in a fluid medium or suspension. It powers two primary functions namely analytical separation (sorting molecules by size / charge) and industrial deposition (applying uniform protective coatings to complex materials).
Electrophorus – It is an instrument which is used to produce electrostatic charge through electrostatic induction.
Electro-photography – It is widely known as xerography. It is a dry, electrical printing and photocopying method. It creates visible images on paper by using light to form electrostatic charge patterns, which then attract oppositely charged toner particles. These particles are subsequently transferred and heat-fused onto the page.
Electro-plate – It is the application of a metallic coating on a surface by means of electrolytic action.
Electro-plated galvanneal coating – It is a specialized metal finishing process which combines electro-deposition with specific alloy characteristics, resulting in a thin, matte, zinc-iron layer designed for superior paint adhesion and corrosion resistance. Unlike conventional hot-dip galvanneal, this process uses an electrochemical method to apply the zinc-iron alloy at room temperature, ensuring high surface precision, which is particularly useful for exposed automotive and home appliance panels.
Electro-plating – It is the electrode-position of an adherent metallic coating on an object serving as a cathode for the purpose of securing a surface with properties or dimensions different from those of the substrate.
Electro-plating solution – It is normally referred to as an electrolyte or plating bath. It is an aqueous solution containing dissolved metal salts, acids, bases, and specialized additives. It acts as the ion-conducting medium which allows metal cations to travel from an anode to a cathode (the work-piece) under the influence of an applied direct current.
Electro-plating technology – It is a manufacturing and surface treatment process which uses an electric current to deposit a thin layer of metal onto a conductive object. It is mainly used to improve a part’s corrosion resistance, durability, electrical conductivity, and aesthetic appeal.
Electro-polymerization – It is an electro-chemical technique used to synthesize and deposit thin polymer films directly onto conductive substrates by applying an electrical potential. By controlling the voltage, monomers undergo oxidation or reduction, creating reactive radicals that link together into polymer chains.
Electro-polishing – It is a technique normally used to prepare metallographic samples, in which a high polish is produced making the sample the anode in an electrolytic cell, where preferential dissolution at high points smoothens the surface. It is also referred to as electrolytic polishing.
Electro-positive -It refers to the tendency of metal atoms to donate electrons and form positive ions (cations), a fundamental characteristic of metallic behaviour. Highly electro-positive metals (e.g., alkali metals, aluminium) are strong reducing agents used to extract other metals, whereas less electropositive (noble) metals are more resistant to corrosion.
Electro-positive elements – These are atoms with a strong tendency to lose valence electrons and form positive ions (cations), a characteristic mainly shown by metals. They are characterized by low ionization energy and low electro-negativity, normally found on the left side of the periodic table. Caesium (Cs) is normally considered the most electro-positive stable element.
Electro-positivity – It is the inherent tendency of metal atoms to lose valence electrons and form positively charged cations. It defines a metal’s reactivity and ability to form ionic bonds, with higher electro-positivity indicating easier electron loss. This property is important for determining extraction methods like electrolysis or pyro-metallurgy.
Electro-reduction – It is an electro-chemical process in which electrons are added to a substance, causing it to be reduced at the cathode of an electrolytic cell. By applying an external electrical current, the process drives non-spontaneous chemical reactions to extract metals, synthesize valuable fuels, or treat pollutants.
Electro-refining – It is using electric or electrolytic methods to convert impure metal to purer metal, or to produce an alloy from impure or partly purified raw materials.
Electro-slag heating (ESH) tundish – It acts as a metallurgical reactor vessel where the steel is heated while flowing between the ladle and the casting mould. Electric current (normally alternating current) is passed through a slag pool, which becomes superheated. This heat transfers to the steel, allowing for precise temperature regulation (+/- 1 deg C to 5 deg C).
Electro-slag heating tundish process – It is an advanced secondary refining process used during continuous casting to precisely control the temperature and chemical composition of molten steel. It works by passing an electric current through a conductive slag layer covering the molten steel, generating heat through ‘joule heating’ (resistance heating).
Electro-slag refining process – It is also called electroslag remelting process. It is a secondary metallurgical process used to remelt and refine metals, mainly steels and superalloys, to produce ultra-clean, high-homogeneity ingots for critical applications. The process involves melting a consumable electrode through a superheated conductive slag, which absorbs impurities before the refined metal solidifies in a water-cooled copper mould.
Electro-slag remelting – It is a consumable-electrode remelting process in which heat is generated by the passage of electric current through a conductive slag. The droplets of metal are refined by contact with the slag.
Electro-slag remelting (ESR) process – It is a consumable-electrode remelting process in which heat is generated by the passage of electric current through a conductive slag. The droplets of metal are refined by contact with the slag. This process is a continuous process. In this process, during the remelting of the consumable electrode, refining and solidification of the steel take place at the same time. Cast, rolled or forged steel ingots can be used as a consumable electrode. The process is based on an electrical current running through an electrode through the liquid slag and ingot. Because of the high electrical resistance of the slag, the slag heats up and melts. The complete remelting process is carried out in a water-cooled copper mould, which allows the remelted ingot to solidify quickly and very uniformly. It is a secondary steelmaking process which is used for remelting and refining of steels and special alloys normally used for critical applications in aircraft, thermal and nuclear power plants, and defense hardware, etc. The main purpose of the electroslag remelting process is to control the non-metallic inclusions in the steel, remove segregations and shrinkage, and produce more homogenous ingots. This process is normally essential for heavy steel ingots.
Electro-slag welding – It is a welding process which produces coalescence of metals with molten slag that melts the filler metal and the surfaces of the work-pieces. The weld pool is shielded by this slag, which moves along the full cross section of the joint as welding progresses. The process is initiated by an arc that heats the slag. The arc is then extinguished by the conductive slag, which is kept molten by its resistance to electric current passing through the electrode and the work-pieces.
Electro-spark deposition – It is a micro-welding process which uses electrical energy to deposit a thin layer of material onto a substrate. It involves creating a series of electrical sparks between an electrode and the work-piece, melting a small amount of both the electrode material and the substrate, and then rapidly solidifying the molten material to form a fused coating. Electro-spark deposition is mainly used for improving surface properties like wear and corrosion resistance, or for repairing damaged components.
Electro-spinning – It is a process for producing nano-fibres with diameters ranging from nano-meters to a few micro-meters by applying an electric charge to a polymer melt or solution, effectively drawing fibres through electrostatic forces. Different materials such as polymers, ceramics, and inorganic compounds can be utilized in this process.
Electro-spinning distance – It is frequently called the needle-to-collector distance. It is the physical gap between the tip of the spinneret (needle) and the grounded target in an electro-spinning setup. It is a critical processing parameter which creates the electric field intensity, determines flight time, and dictates whether the ejected polymer jet dries sufficiently before deposition.
Electro-spinning jet – It is a slender, continuous stream of electrified fluid (a polymer melt or solution) which is ejected from a nozzle under high voltage. It elongates, thins, and solidifies into continuous nano-fibres as the solvent evaporates on its way to a grounded collector. The formation and behaviour of the jet involve a precise series of physical and electrical phenomena namely jet initiation (the Taylor cone, the straight segment, bending instability (the whipping process), and solidification and collection.
Electro-spinning method – It is a fibre-production method which uses high-voltage electrostatic forces to draw and stretch charged threads of polymer solutions or melts. It produces continuous, ultra-fine fibres, ranging from nano-meters to a few micro-meters in diameter, with high surface-to-volume ratios and porous structures.
Electro-spinning post – It is frequently called post-electrospinning modification or post-treatment. It refers to the different chemical, and physical processes applied to electro-spun nano-fibres after their initial fabrication. These steps are used to improve properties like strength, or conductivity capabilities.
Electro-spinning process – It is a technique which utilizes electric forces to draw charged threads of polymer solutions, forming fibrous structures at the nano-meter or micro-meter scale. This process involves applying a high voltage to a liquid droplet, which elongates and deposits fibers, resulting in a highly fibrous scaffold with tunable fibre width and mechanical properties.
Electro-spinning set – It is the assembly of equipment used to draw polymer solutions or melts into ultrafine fibres using high-voltage electricity. This process creates solid, non-woven continuous fibres with diameters ranging from the nano-meter to micro-meter scale.
Electro-spinning solution – It is a liquid mixture consisting of a polymer completely dissolved in a volatile solvent. It is utilized in the electro-spinning process, where a high-voltage electric field draws the charged solution into ultra-fine nano-fibres or micro-fibres. Key properties of the solution include to produce uniform, bead-free fibres, the electro-spinning solution is to meet specific physical and chemical criteria.
Electro-spinning technique – It is a method for fabricating nano-fibres from polymer solutions by applying high voltage to create a charged droplet that forms a jet, leading to the production of fibres with a high surface-to-volume ratio. The structural properties of the resulting nano-fibres are influenced by factors such as polymer concentration, delivery rates, air gap distance, and applied voltage.
Electrospray – It is a technique which uses high-voltage electricity to disperse a liquid into a fine, electrically charged aerosol. It relies on electrostatic forces to draw the liquid into a conical shape (the Taylor cone) before breaking it down into tiny, highly charged droplets.
Electrospray ionization – It is a soft, atmospheric-pressure technique used in mass spectrometry to generate gas-phase ions from liquid samples by applying high voltage to create an aerosol. It creates multiply-charged droplets without breaking molecules apart, enabling identification of thermally labile macro-molecules, complex supra-molecules, and trace elements.
Electro-spun – It refers to micro-fibres or nano-fibres which are produced using a high-voltage electrical field to draw and stretch a charged polymer solution or melt into ultra-fine threads. This process, known as electro-spinning, yields extremely thin, non-woven fibre mats with unique properties like high porosity and a massive surface-to-volume ratio.
Electro-spun composite nano-fibres – These are ultra-fine, nano-scale fibres fabricated through electro-spinning, a high-voltage electrostatic process which stretches a charged polymer liquid jet into continuous fibres. These fibres are characterized by a high surface-to-volume ratio, high porosity, and the integration of multiple distinct materials to achieve improved structural, and functional properties.
Electro-spun fibres – These are micro-fibres or nano-fibres produced by drawing polymer solutions or melts through a high-voltage electrostatic field. This electrostatic force elongates and thins the fluid into continuous, ultra-fine threads which collect as a non-woven mesh. These fibres are highly prized for their immense surface-to-volume ratio and porous structure.
Electro-spun jet – It is a slender, continuous, and electrically charged filament of fluid ejected from a polymer solution or melt. It is formed when electrostatic repulsion overcomes the fluid’s surface tension, causing the droplet at the tip of a nozzle to deform into a cone (Taylor cone) before accelerating toward a collector. As the jet travels, it undergoes a complex sequence of physical and electrical transformations as it solidifies into nano-fibres.
Electro-spun mat – It is a non-woven sheet of ultra-fine fibres, typically ranging from nano-meters to micro-meters in diameter produced using electro-spinning technology. This process uses a high-voltage electric field to draw a liquid polymer solution or melt into continuous fibres, which collect as a highly porous, interconnected mesh.
Electro-spun materials – These are ultrafine fibres or non-woven 3D scaffolds produced through electro-spinning, a technique which uses high-voltage electricity to draw a charged polymer solution or melt into continuous nano-scale fibres. They are valued for their extremely high surface-to-volume ratio, adjustable porosity, and customizable morphology. Since these materials can be engineered from a massive variety of natural and synthetic polymers, ceramics, and composites, they are highly adaptable. Their unique properties are leveraged across several key fields.
Electro-spun nano-fibres – These are ultra-thin, continuous fibres produced using a high-voltage electrostatic field to stretch and solidify polymer solutions or melts. They typically feature diameters ranging from tens to hundreds of nano-meters, offering an extraordinarily high surface-to-volume ratio and a highly porous, non-woven mesh structure.
Electro-spun nano-fibre membrane – It is a highly porous, non-woven mat of ultra-fine fibres (ranging from tens of nano-meters to a few micro-meters) produced through a high-voltage electrostatic field. These membranes are prized for their extremely high surface area-to-volume ratio, interconnected pore structures, and superior permeability.
Electro-spun scaffold – It is a non-woven, highly porous mesh of micro-scale or nano-scale fibres fabricated using a high-voltage electrical field to spin polymers.
Electro-spun polymer nano-fibres – These are ultra-fine solid fibres formed by stretching an electrically charged liquid polymer solution or melt. Through a high-voltage electrostatic field, the polymer is elongated into a continuous, nano-scale thread which is deposited as highly porous, non-woven sheets.
Electrostatic actuation – It is a mechanism which generates mechanical motion or force by utilizing attractive or repulsive Coulomb forces between electrically charged bodies. When voltage is applied across conductive electrodes, it creates an electric field which causes the movable parts to shift, serving as the driving force for microscopic machines.
Electrostatic application – It uses static electricity to manipulate, coat, or separate materials. By imparting an electrical charge to particles, they are attracted to an oppositely charged or grounded target. This highly efficient method reduces waste, improves adhesion, and is necessary in manufacturing, pollution control, and printing.
Electrostatic application of lubricants – It is an advanced technique where lubricant particles (typically dry powders or mist) are electrically charged and sprayed onto a surface. Using high-voltage charging, the particles are strongly attracted to the electrically grounded target, ensuring uniform, thin-film deposition with minimal waste, frequently used in powder metallurgy, die wall lubrication, and high-velocity precision machining.
Electrostatic attraction -It is a non-contact force which pulls together objects or particles with opposite electrical charges (positive and negative). It is governed by fundamental physical rules where opposite charges attract and like charges (positive / positive or negative / negative) repel each other.
Electrostatic charge – It is a stationary build-up of electric charge on the surface of a material, typically caused by a gain or loss of electrons. When two materials come into contact, electrons can transfer, leaving one with a positive charge and the other with a negative charge.
Electrostatic coating – It is an advanced painting and finishing technique where electrically charged particles (liquid paint or dry powder) are sprayed onto a grounded target. Since the particles and the substrate hold opposite electrical charges, the coating is magnetically attracted to the surface, resulting in an exceptionally even, durable, and highly efficient application.
Electrostatic contribution – It refers to the portion of a total physical, or chemical property (such as energy, force, or binding affinity) which arises directly from the Coulombic interactions, attractive or repulsive forces, between static electric charges.
Electrostatic coupling – It is frequently called capacitive coupling. It is the transfer of electrical energy between two or more conductors in close proximity through an electric field. A changing voltage on one conductor creates an electric field which induces a corresponding voltage on a nearby conductor.
Electrostatic discharge – It is the sudden and momentary flow of electric current between two electrically charged objects caused by contact, an electrical short, or dielectric breakdown. It occurs when objects with different electrical potentials come into close proximity, frequently resulting in a visible spark or a felt, tiny shock.
Electrostatic driving – It is also called electrostatic actuation. It is a mechanical or physical actuation method that uses the attractive or repulsive forces between electric charges to create movement. It is the fundamental mechanism behind micro-electro-mechanical systems (MEMS), certain types of propulsion, and specialized motors.
Electrostatic field – It is the invisible region of force surrounding a stationary electric charge. It dictates how other charged particles in its vicinity interact, pulling opposites together and pushing likes apart. It is a specific, time-invariant type of electric field generated entirely by charges at rest.
Electrostatic filters – These are devices designed to separate electrically charged particulates, such as dust and tar droplets, from a gaseous stream by utilizing electrostatic forces, which can be significantly stronger than gravitational forces. These filters operate by ionizing gas molecules and charging the particulates, allowing them to be collected on grounded electrodes.
Electrostatic filtration – It is a physical separation process which uses electrical charges to attract and trap airborne or fluid-borne particles. It ionizes particles so that electrostatic forces, which are considerably stronger than gravity, pull them onto oppositely charged collector plates or specialized filter media.
Electrostatic focusing device – It is a device which effectively increases the angular aperture of the electron beam illuminating the object, rendering the focusing more critical.
Electrostatic force – It is the force of attraction or repulsion between electrically charged objects because of their electric charge. This force is also known as the Coulomb force. It arises from the interaction between charges and can be attractive (opposite charges) or repulsive (like charges). Electrostatic forces arise from the charge of two interacting surfaces, which can be two solid surfaces, but can also relate to a solid surface and a bacterium.
Electrostatic force and adhesion – Electrostatic force is the attractive or repulsive force between charged particles or objects. Adhesion is the tendency of dissimilar surfaces, molecules, or materials to stick together. When combined, electrostatic adhesion refers to how electrical charges and interactions, such as induced dipoles or electrical double layers at an interface, drive materials to attract and bond to one another.
Electrostatic hazard – It is the danger posed by the uncontrolled generation, accumulation, and sudden discharge of static electricity. The rapid release of energy (an electrostatic discharge, or ESD) creates a spark which can ignite flammable gases, vapours, or combustible dusts, leading to fires and explosions.
Electrostatic immersion lens – It is a lens system in which the object space is at a potential or in a medium of index of refraction different from that of the image space.
Electrostatic induction – It is the redistribution of electric charge within a conductor, such as metal, caused by the influence of a nearby charged object without direct contact. This process separates charges, inducing opposite charges on the near side of the material, attracting it, and creating potential difference.
Electrostatic lens – It is a lens producing a potential field capable of deflecting electron rays to form an image of an object.
Electrostatic motor – It is a motor which relies on the forces generated by electric fields, instead of magnetic fields.
Electrostatic painting – it is an advanced spray-coating technique which uses static electricity to apply paint to conductive surfaces, typically metals. By applying an electrical charge to the paint and creating an opposite charge on the object being painted, the paint is magnetically drawn to the surface, ensuring an even, highly efficient coat.
Electrostatic potential – It is the quantity of work done by an external force to bring a unit positive test charge from infinity to a specific point in a static electric field, without accelerating it. It represents the potential energy per unit charge at that exact location.
Electrostatic potential energy – Electrostatic potential energy (Uei), like all energy, is a measure of the ability of a system to do work. In the case of electrostatic potential energy, the system is composed of charged particles which interact through electrostatic forces. Like all potential energies, the value of ‘Uei’ is measured relative to a reference configuration for which the potential energy is chosen to be equal to zero. Normally, electrostatic potential energy is specified to be equal to zero when the charges constituting the system are separated by an infinite distance. Then ‘Uei’ for a system of charges in a given configuration is equal to the work which is done against the electrical forces in order to assemble that configuration from an initial state of infinite separation of the charges. This work, and, hence, the energy of the configuration, is also equal to the work which the electrical forces among the charges performs as the charges are caused to be separated by an infinite distance.
Electrostatic precipitator – An electrostatic precipitator is a particulate collection device which removes particles from a flowing gas (such as exhaust gas) using the force of an induced electrostatic charge. Electrostatic precipitators are highly efficient filtration devices which minimally impede the flow of gases through the device, and can easily remove fine particulate matter from the exhaust gas stream. Electrostatic precipitator applies energy only to the particulate matter being collected and therefore is very efficient in its consumption of energy (in the form of electricity). It consists of (i) baffles for the distribution of the flow of exhaust gas, (ii) discharge and collection electrodes, (iii) a dust clean-out system, and (iv) collection hoppers. A high DC (direct current) voltage is applied to the discharge electrodes to charge the particles, which then are attracted to oppositely charged collection electrodes on which they get trapped.
Electrostatic printing – It is a dry reproduction process which uses static electricity to attract and bind dry toner or ink to a substrate. It works by creating an invisible electrostatic ‘latent image’ on a charged surface, which then attracts oppositely charged pigment particles which are subsequently fused using heat or pressure. The electrostatic printing process relies on a few fundamental concepts namely latent imaging, toner attraction, and transfer and fusing.
Electrostatic propulsion – It is an advanced class of electric propulsion which accelerates ionized propellant to extremely high speeds using direct electric fields. By utilizing electrical energy rather than chemical combustion, it generates very little thrust but achieves incredible fuel efficiency, making it ideal for long-duration deep-space missions and satellite maneuvering.
Electrostatic repulsion – It is a pushing force which occurs when two objects or particles with the same type of electric charge (both positive or both negative) come close to each other. Since ‘like’ charges repel, this force drives them apart.
Electrostatics – It is the study of stationary electric charges and resulting forces. It is a branch of physics which studies slow-moving or stationary electric charges. Since classical times, it has been known that some materials, such as amber, attract lightweight particles after rubbing.
Electrostatic screen – It is also called electrostatic shield. It is a conductive barrier or enclosure used to block external electric fields from penetrating a specific region. By redistributing induced surface charges, the barrier neutralizes the internal electric field, protecting delicate instruments, audio cables, and electrical circuits from electromagnetic interference.
Electrostatic sensor – It is a non-contact, passive device which detects changes in an electrostatic (electric) field. By relying on electrostatic induction, these sensors measure the movement of static charges or particles without requiring direct physical contact with the target object.
Electrostatic spray – It is the process by which paint particles are electrically charged and attracted to a substrate bearing an opposite charge.
Electrostatic theory – It is the branch of physics and electromagnetism which studies stationary or slow-moving electric charges. It defines how charged particles interact, store energy, and generate electric fields and potentials without the influence of magnetic effects. The theoretical framework is necessary for explaining everyday phenomena (like static cling or lightning) as well as technological applications (like capacitors and powder coating).
Electrostrictive effect – It is the reversible interaction, showed by some crystalline materials, between an elastic strain and an electric field. The direction of the strain is independent of the polarity of the field.
Electrostrictive constant – It is also called electrostrictive coefficient. It quantifies a material’s mechanical deformation (strain) in response to an applied electric field. Unlike piezoelectricity, which is linear and reversible, electrostriction is a quadratic effect. This means the deformation is proportional to the square of the electric field or polarization, and the direction of expansion or contraction does not change if the polarity of the electric field is reversed.
Electrostrictive materials – These are dielectrics which change shape (strain) when exposed to an electric field. Unlike the linear piezoelectric effect, electrostrictive strain is quadratic, meaning deformation is proportional to the square of the applied field, so the direction of shape change remains the same regardless of the field’s polarity.
Electro-synthesis – It is the production of chemical compounds through electro-chemical reactions, where electricity is used to drive oxidation or reduction rather than using traditional chemical reagents. It offers a sustainable alternative to conventional synthesis, frequently increasing reaction selectivity, reducing hazardous waste, and enabling precise control over reaction rates through potential adjustment.
Electro-textiles – These are frequently called e-textiles or electronic textiles. These are fabrics which have electronic components, such as conductive threads, sensors, and micro-controllers, seamlessly integrated into their structure. They represent a fusion of traditional textiles and wearable technology, allowing clothing and fabrics to sense, react, and communicate.
Electro-thermal atomization atomic absorption spectroscopy (ETA-AAS) – It is frequently called graphite furnace atomic absorption spectroscopy (GF-AAS). It is a highly sensitive analytical technique used to determine the concentration of metal elements in a sample. It works by introducing a small sample into a graphite tube, which is then heated electrically in stages (drying, ashing, atomization) to generate free atoms which absorb light at specific wave-lengths, with absorption proportional to the concentration.
Electro-thermal furnaces – These are the furnace which uses electricity for the generation of heat.
Electro-tinning – It consists of electro-plating of tin on an object.
Electro-typing – It is the production of printing plates by electro-forming.
Electro-upsetting – It is also called electric upsetting. It is a thermal-mechanical forging process used to enlarge the diameter of a metal bar by heating it with high-amperage electrical current while applying hydraulic pressure. It is used to create large ‘onion’ heads on bars, which are then used as preforms for further forging in producing items like engine valves, shafts, and axles.
Electro-winning – It is the recovery of a metal from an ore by means of electro-chemical processes. It is a process which uses an electric current to extract and recover metals from a solution, typically a leach solution, by plating them onto a cathode. This process, also known as electro-extraction, is widely used in mining, refining, and recycling industries for extracting metals like copper, gold, silver, and zinc.
Element – It is a chemical substance which cannot be broken down into other substances by chemical reactions. The basic particle which constitutes an element is the atom. Element is identified by the number of protons in its nucleus, known as the element’s atomic number. Element cannot be broken down into simpler substances. It retains its basic physical properties, regardless of the number of atoms in a sample.
Elemental – It refers to the use of pure, unalloyed metallic powders as raw materials, rather than pre-mixed alloy powders.
Elemental analysis – Elemental analysis is a process where a sample of some material is analyzed for its elemental and sometimes isotopic composition. Elemental analysis can be qualitative, and it can be quantitative. It also consists of the determination of the percentage composition of the different elements present in an organic compound. It is one of the oldest quantitative techniques. It remains one of the first steps taken to investigate a new or unknown substance. The determination of the elemental composition of a sample normally enables the writing of an empirical formula for the substance under investigation, i.e., writing a formula expressing the relative number of the different atoms present. Some examples of empirical formulas are CH4 (methane, natural gas), HC2H3O2 (acetic acid), and C2H6O (ethyl alcohol).
Elemental approach – It means physically blending pure metal powders (e.g., iron, copper, carbon) in precise proportions before compacting and sintering them
Elemental carbon – It refers to uncombined carbon which exists as a distinct, pure phase, very frequently graphite. Unlike combined carbon (which forms compounds with iron like cementite or carbides), elemental carbon dictates specific mechanical properties, machinability, and brittleness in iron and steel alloys.
Elemental chlorine (Cl2) – It is a highly reactive, yellow-green gas used mainly to extract, separate, and refine metals from complex ores and waste materials. It acts as a powerful oxidizing agent to convert target metals into volatile or water-soluble metal chlorides.
Elemental composition – It refers to the exact types and quantitative proportions of chemical elements which make up a metal or alloy. It determines physical, mechanical, and chemical properties like strength, corrosion resistance, and malleability.
Elemental mercury – It is pure mercury rather than a mercury containing compound, the vapour of which is normally used in fluorescent and other light bulb types.
Elemental metal – It is a pure chemical substance consisting of only one type of atom (e.g., iron, copper, gold). It serves as the fundamental building block of the field and is contrasted with alloys, which are deliberate mixtures of multiple elements. Elemental metals in their pure form possess distinct, standardized properties.
Elemental phase – It refers to a physically homogeneous region of a pure metallic element with uniform chemical composition and a distinct, repeating crystalline structure, e.g., face-centered cubic (fcc) or body-centred cubic (bcc). While pure metals have just one elemental phase at a time, changing the temperature or pressure causes distinct phase transformations into different solid structures.
Elemental semi-conductor – It is a material composed of a single, pure chemical element from the periodic table (very frequently group IV) which shows electrical conductivity between that of a conductor and an insulator. These unmixed, intrinsic materials typically form crystalline structures, such as a diamond lattice.
Elemental sulphur – It refers to uncombined, non-metallic sulphur used as a chemical reagent, slag former, or vulcanizing agent. It mainly aids in separating valuable metals from impurities, converting metals into stable sulphides, or creating specialized copper and iron alloys.
Elemental thrust – It is an incremental or localized unit of a total propulsive force. It is very frequently used to describe the specific force generated by an isolated, microscopic portion of a system, such as a single segment of a wind turbine.
Elemental volume – It is the smallest, infinitesimal, or finite portion of a material or fluid domain. It serves as the fundamental building block for modeling physical behaviours like stress, fluid flow, or heat transfer, allowing engineers to derive mathematical equations across a system.
Element antennas – These are the most widely used out of the three main types of antennas. Some examples of element antennas are the monopole, dipole, and bowtie antenna. This class of antennas is nondispersive, it is characterized by linear polarization and low directivity, and some of them have a relatively limited bandwidth. The radiation characteristics of element antennas are well understood. The calculation of the radiated field is based on the approximation of the current distribution on the antenna by a number of elementary currents.
Elementary beam theory – It is also known as the Euler-Bernoulli or classical beam theory. It is a foundational engineering framework used to calculate the load-carrying capacity, stress, and deflection of slender beams. It simplifies complex three-dimensional elasticity problems by assuming that cross-sections remain perfectly plane and perpendicular to the beam’s neutral axis during bending.
Elementary charge (e) – It is the fundamental physical constant equal to the magnitude of the electric charge carried by a single proton or electron. It is the smallest discrete unit of charge which can exist independently in nature. By exact definition, the elementary charge is ‘e = 1.602176634 times 10 to the power -19 coulombs (C)’.
Elementary fibre – It is the most basic, fundamental unit of a fibrous material. It represents a single, individual cell rather than a bundled strand, typically possessing an elongated structure with a defined cell wall and a hollow central core.
Elementary magnetic moment – It is the fundamental vector quantity which represents a particle’s intrinsic strength and orientation to generate a magnetic field or align with an external field. For electrons, it stems from orbital motion and intrinsic spin, measured in fundamental units called Bohr magnetons.
Elementary matrix – It is a square identity matrix which has been altered by exactly one single elementary row operation. In engineering, multiplying a system matrix by an elementary matrix is a powerful, systematic way to perform operations like Gaussian elimination, matrix inversion, and system solving. There are three types of elementary matrices, corresponding to the three basic row operations. These are row swap (interchange), row scaling, and row addition (replacement).
Elementary reaction – It is a chemical reaction in which one or more chemical species react directly to form products in a single reaction step and with a single transition state, i.e. without any intermediates.
Elementary row operations – These are three fundamental, reversible manipulations applied to the rows of a matrix to transform it into simpler forms, such as row-echelon or reduced row echelon form (RREF). These operations, which preserve the row equivalence of matrices, include switching two rows, multiplying a row by a non-zero scalar, and adding a multiple of one row to another.
Elementary solution – It normally refers to a foundational, basic, or uncomplex approach utilized to solve a problem. It frequently serves as a baseline configuration, a fundamental building block of a larger system, or a basic analytical function used to model a complex physical phenomenon.
Elementary theory – It refers to the simplest, classical mathematical approximations used to model physical systems, structures, or materials. It streamlines complex 3D behaviours into manageable 1D or 2D equations by applying simplifying geometric and physical assumptions. The most prominent example is the elementary beam theory (also known as the Euler-Bernoulli beam theory).
Elementary transformations – These are fundamental, reversible operations applied to the rows or columns of a matrix. They are mainly used to solve systems of linear equations, invert matrices, and determine matrix rank, all without altering the underlying solution.
Elementary wave – It is the fundamental, sinusoidal building block of a wave (e.g., a pure sine or cosine wave). In hyperbolic partial differential equations (PDEs), it refers to simple, foundational solutions like shocks, rarefactions, or contact discontinuities which describe how information or disturbances propagate through a medium.
Element balance – It is the mathematical accounting of specific chemical elements (e.g., carbon, hydrogen, oxygen) entering and leaving a system. Based on the law of conservation of mass, it ensures that the total moles of an element in the reactants equal the total moles of that element in the products.
Element behaviour – It defines how specific metallic and non-metallic elements physically and chemically interact, migrate, and distribute within alloys or during processing. It dictates whether elements dissolve, segregate to grain boundaries, form new compounds, or are eliminated as waste. Understanding element behaviour is the foundational core of both chemical and physical metallurgy. It is broken down into two primary field namely chemical (extractive) element behaviour and physical (alloy) element behaviour.
Element composition – It refers to the specific types and exact proportions of chemical elements which make up a metal or alloy. It is the foundation of material science, determining a metal’s mechanical, thermal, and chemical behaviour, including strength, ductility, and corrosion resistance.
Element co-ordinate system – It is a local, right-handed orthogonal system used in metallurgical engineering and computational mechanics. It orients non-isotropic material properties, applies directional surface pressures, and measures structural responses like stress, strain, and thermal gradients.
Element discretization – It is the process of breaking down a continuous geometric domain or mathematical system into a finite number of smaller, manageable subdivisions (elements). It is the foundational first step of numerical simulations like finite element analysis (FEA) or finite element method (FEM).
Element-free Galerkin (EFG) method – It is a meshless numerical technique used to solve partial differential equations (PDEs) by constructing shape functions based on scattered nodes rather than pre-defined element connectivity. It uses the moving least squares (MLS) approximation to formulate the solution, making it highly effective for large deformation and fracture problems. It is widely used to model processes involving large deformations, complex material flow, and fracture mechanics. Unlike the finite element method (FEM), it does not need a predefined element connectivity, making it superior for problems where elements otherwise become excessively distorted.
Element generation – It is the process of programmatically creating UI (user interface) components, DOM (document object model) objects, or structural data. It is mainly used in web development and software engineering to dynamically build, modify, and display interactive content on a screen based on user actions or external data sources.
Element mass matrix – In the finite element method (FEM), it is a mathematical representation of a structure’s continuous mass distribution within an individual element. It relates nodal forces to nodal accelerations and is used to solve dynamic structural problems, such as vibrations, impacts, and seismic responses.
Element model – It is a fundamental building block used to describe the relations of variables and loads in a specific segment of a larger system. It simplifies complex spatial or systemic problems into localized, interconnected components to predict overall behaviours.
Element multiplication – It is also known as element-wise multiplication or the Hadamard product. It is a mathematical operation where two matrices or vectors of the exact same dimensions are multiplied together. It multiplies the corresponding elements in the exact same positions to produce a new matrix of the same size.
Element processes – These refer to a series of operations or fundamental steps involved in treating, creating, or manipulating components, frequently used in engineering, manufacturing, or computer science contexts. They represent the granular, individual steps or inputs (like materials or machinery) which, when combined, create a, fully defined, functional process.
Element shape function – It is a mathematical interpolation formula used mainly in finite element analysis (FEA) to approximate field variables (like displacement or temperature) within the boundaries of a discrete geometric element using the known values at its nodes.
Element specie – It is a specific chemical form of an element, defined by its molecular structure, oxidation state, or complexed state. Since elements can exist in multiple forms. each with vastly different chemical, physical, and biological properties, this concept is important for understanding environmental toxicity and industrial processes.
Element stiffness matrix – It is a mathematical representation which relates nodal forces to nodal displacements for a single discrete portion (or element) of a structure. It serves as the fundamental building block of the finite element method (FEM) and structural analysis.
Element transformation – It refers to the process of changing the state, structure, coordinates, or mathematical representation of a distinct unit (an element).
Elevated pressure – It refers to the application of increased pressure to enable solvents to operate above their boiling points, improving solvation power and extraction kinetics, hence improving extraction efficiency and reducing the consumption of organic solvents and operation time.
Elevated storage – It refers to a method of storing water in a structure, such as a water tower, positioned above ground level to maintain necessary pressure in the distribution system. This approach is frequently more expensive to construct and maintain compared to ground-level storage but can allow for shorter connection pipelines.
Elevated temperatures – These refer to conditions considerably higher than ambient, typically causing physical property /chemical property changes in materials, such as reduced strength or creep. It frequently refers to operating environments exceeding 100 deg C for liquids, 240 deg C for solids in transport, or 800 deg C in specialized, high-heat systems. These are the temperatures high enough to alter the microstructure, durability, and strength of materials like concrete or steel, frequently evaluated regarding fire safety.
Elevated-temperature fracture – It is the failure or cracking of materials under high-temperature conditions, typically occurring at temperatures higher than 0.3 times to 0.5 times the absolute melting point (Tm) of the material. At these temperatures, fractures are normally time-dependent and driven by both mechanical load and thermally activated processes, such as creep, rather than solely by instantaneous tensile stress.
Elevated-temperature tensile testing – It is a procedure which measures material properties, such as yield strength, ultimate tensile strength, and ductility, under tension while subjected to temperatures above ambient, typically using a furnace. It evaluates how materials behave under heat and load, normally following the International Organization for Standardization standard ISO 6892-2.
Elevation – It refers to the vertical distance of a point, object, or structure above or below a fixed reference datum, typically sea level, a benchmark, or a designated ‘grade’. It is used to define height for topography and construction, ensuring precise vertical alignment of foundations, floors, and structural elements.
Elevation head – It is also known as potential head or static lift. It refers to the potential energy of a fluid, such as molten metal, slurry, or water, because of its elevation above a specific reference datum (reference level). It represents the vertical distance a fluid must travel and is a key component in calculating total hydraulic head, which determines fluid flow and pressure in piping, casting, or mineral processing systems.
Elevation view – It is a two-dimensional, flat, straight-on orthographic projection of a building or structure’s exterior (or interior) facade. Unlike a floor plan which shows a bird’s-eye view looking down, an elevation view shows a structure from the side, detailing vertical measurements, heights, and features.
Elevator – It is a machine that vertically transports people or materials between levels. They are typically powered by electric motors which drive traction cables and counterweight systems such as a hoist, although some pump hydraulic fluid to raise a cylindrical piston like a jack. Elevators are used in manufacturing to lift materials. There are several types such as chain and bucket elevators, grain augers, and hay elevators.
Elevator angle – It is the angular displacement of the elevator from its neutral position. It is positive when the trailing edge of the elevator is below the neutral position, and negative when it is above.
Elevator belt – It is used for vertical conveying, with buckets mounted to it.
Elevator shaft – It is also called hoist-way. It is a vertical, enclosed tubular space within a building that provides a dedicated path for an elevator car to travel between floors. It serves as a structural core and houses the car, counterweights, guide rails, and important safety systems.
Eley-Rideal mechanism – It is a fundamental concept in heterogeneous catalysis where a gas-phase reactant collides and reacts directly with a chemically adsorbed species on a solid surface. Unlike other pathways, it skips the step where the second reactant adsorbs onto the catalyst.
Ellipse – It is a closed, symmetric curve resembling a flattened circle or oval, defined mathematically as the locus of points where the sum of the distances to two fixed points (foci) is constant. It is a conic section formed by intersecting a cone with a plane, normally used to describe planetary orbits and elliptical shapes in design. It refers to the geometric shape of features observed in micro-structures or fracture surfaces. It is normally used to describe the shape of particles, pores, or grains which have been deformed, or the shape of a crack propagation front.
Ellipsoid – It is a 3D quadratic surface defined by three principal semi-axes. It is the 3D equivalent of an ellipse and is widely used for modelling planetary bodies, structural confidence regions, fluid-particle shapes, and iterative optimization algorithms.
Ellipsoid algorithm – It is an iterative mathematical method used in engineering and computer science to solve convex optimization problems and systems of linear inequalities. It is historically significant as the first algorithm proven to solve linear programming (LP) problems in polynomial time, confirming that such problems are computationally ‘efficient’ to solve (P complexity class).
Elliptical area – It is the total two-dimensional space enclosed by an ellipse. In structural and mechanical fields, it is also used dynamically to represent energy dissipated per cycle in damping models.
Elliptical bearing – It is a two-lobed bearing. It is one type of non-circular journal bearing which has two main advantages over the conventional circular bearings namely lower temperature rise and lower vibrations.
Elliptical crack – It is a 3D structural flaw where the crack front forms a semi-elliptical or fully elliptical shape. It is the standard geometric model used in fracture mechanics to analyze naturally occurring surface, corner, or embedded fatigue cracks in materials subjected to applied stresses.
Elliptical distribution – It is a broad family of multivariate probability distributions which generalizes the multivariate normal distribution. It is characterized by symmetric, elliptical contours of equal probability density, allowing engineers to model complex, heavy-tailed, or skewed data.
Elliptical duct – It is a conduit with an oval-shaped cross-section. It combines the structural rigidity and superior aerodynamic airflow of round ducts with the space-saving, low-profile footprint of rectangular ducts. It is widely used in HVAC (heating, ventilation, and air conditioning) systems with height restrictions.
Elliptical head – It is also called ellipsoidal head. It is a pressure vessel end cap shaped like a half-ellipse. Its semi-elliptical cross-section distributes internal stress evenly, making it an efficient, economical, and space-saving choice for containing medium-pressure to high-pressure liquids and gases.
Elliptical hole – It is a geometrical cutout defined by its major and minor axes, modeled by the equation x-square/c-square + y-square/b-square =1. It is mainly used to manage structural stress, as orienting its elliptical radii correctly minimizes stress concentration compared to circular holes.
Elliptical gears – A set of like elliptical gears can run at a constant centre distance, but deliver an output speed that changes as they rotate. Elliptical gears come in two basic types (i) uni-lobe, which rotates about one of two fixed points on its long axis, and bi-lobe, which rotates about its centre. The speed-reduction ratio of these gears varies from ‘1/K’ to ‘K’ during each cycle of rotation, where practical values of ‘K’ range up to 3. As the gears rotate, the radii of the driving and driven gears change, so that speed first decreases for 1/4 revolution, then increases for 1/4 revolution, etc. These periods of increasing or decreasing speed occur four times per revolution. Elliptical gears are normally used in packaging and conveyor applications.
Elliptical nozzle – It is a fluid-handling device featuring a discharge orifice with an oval, cross-sectional geometry. By breaking axisymmetry, these nozzles introduce asymmetric shear and vortex structures, which accelerate fluid mixing, improve atomization, and optimize spatial distribution compared to standard circular designs.
Elliptical orbit – It is a closed, oval-shaped orbital path defined as having an eccentricity (e) higher than 0 but less than 1. It is characterized by two foci, with the central body at one focus, and it includes distinct points of closest approach (perigee / perihelion) and farthest distance (apogee / aphelion).
Elliptical plate – It is a flat structural element shaped like an oval, defined by a major and minor axis. These plates are used in specialized applications, such as pressure vessels, aerodynamic surfaces, and acoustic diaphragms, where specific stress distributions or fluid flow characteristics are needed.
Elliptical ring – It is a structural or mechanical component defined by a continuous, oval-like loop with an inner and outer boundary. Unlike circular rings, their geometry is defined by two unequal axes, a major axis and a minor axis, which dictate how they handle structural stress and vibration. Engineers utilize elliptical rings and related components across several distinct disciplines.
Elliptical shape – It refers to a closed, continuous, and symmetrical curve resembling a flattened or stretched circle. It is the locus of all points where the sum of distances to two fixed points (foci) remains constant. It is widely used for optimal stress distribution and fluid flow.
Elliptical vibration – It refers to a controlled, two-dimensional oscillatory motion where a component (such as a cutting tool or surface texture generator) moves in an oval or elliptical trajectory. It is mainly used in ’elliptical vibration-assisted machining’ (EVAC).
Elliptical vibration-assisted machining – It is an advanced, ultra-precision manufacturing process. It superimposes a localized, high-frequency, two-dimensional elliptical vibration onto a cutting tool or work-piece. This controlled oscillation creates a unique, cyclic ‘micro-chiseling’ and intermittent separation motion between the tool and the material. Elliptical vibration-assisted machining (EVAC) is mainly used to machine ‘difficult-to-cut’ materials. It solves the traditional problem of rapid tool wear when cutting ferrous metals with diamond tools, and prevents brittle fracture in hard ceramics.
Elliptic distribution – It is a broad family of multivariate probability distributions whose contours of constant probability density are concentric ellipses. It generalizes the multivariate normal (Gaussian) distribution, retaining its geometric properties while allowing for heavier tails or extreme outliers.
Elliptic filter – It is also called Cauer filter. It is a signal processing filter defined by equi-ripple (equalized) magnitude behaviour in both its passband and its stopband. It uses mathematically derived transmission zeros to achieve the sharpest possible transition between passing and blocking frequencies for any given filter order.
Elliptic function – It is a doubly periodic, meromorphic function in the complex plane. Just as standard trigonometric functions (e.g., sin x) describe periodic phenomena using a single real period, elliptic functions represent processes governed by two independent complex periods. These functions are frequently used to solve non-linear differential equations, map fluid flows, and analyze wave propagation.
Elliptic hole – It is a geometrical feature in a material characterized by an oval-shaped opening. It is mainly studied for how it disrupts uniform stress distribution, leading to a maximum concentration of stress at the ‘foot’ (the ends of the major axis) when the material is subjected to external loads. Understanding elliptic holes is important for evaluating structural integrity and preventing mechanical failure.
El Nino-Southern Oscillation – The term El Nino has been initially used to describe a warm-water current that periodically flows along the coast of Ecuador and Peru, disrupting the local fishery. It has since become identified with a basin-wide warming of the tropical Pacific Ocean east of the dateline. This oceanic event is associated with a fluctuation of a global-scale tropical and sub-tropical surface pressure pattern called the Southern Oscillation. This coupled atmosphere-ocean phenomenon, with preferred time scales of 2 years to around 7 years, is collectively known as the El Nino-Southern Oscillation. It is often measured by the surface pressure anomaly difference between Darwin and Tahiti and the sea surface temperatures in the central and eastern equatorial Pacific. During an El Nino-Southern Oscillation event, the prevailing trade winds weaken, reducing upwelling and altering ocean currents such that the sea surface temperatures warm, further weakening the trade winds. This event has a great impact on the wind, sea surface temperature, and precipitation patterns in the tropical Pacific. It has climatic effects throughout the Pacific region and in many other parts of the world, through global teleconnections. The cold phase of El Nino-Southern Oscillation is called La Nina.
Elongated alpha – It is a fibrous structure brought about by unidirectional metalworking. It can be improved by the prior presence of blocky and / or grain-boundary alpha.
Elongated grain – It is a grain with one principal axis slightly longer than either of the other two.
Elongated particle – It is a granular material or aggregate whose length is considerably larger than its width or thickness. Defined mainly by their dimensional aspect ratio (length to thickness or length to mean dimension), these particles are prone to breaking and can negatively impact structural strength and material compaction.
Elongated region – It is an area, shape, or geographic feature which is considerably longer in one direction than it is wide. The term is used across multiple fields.
Elongated shaped inclusions – These are internal imperfections within a material, such as steel, which have a long, slender form, with a length considerably higher than their width. These inclusions are characterized by a high aspect ratio, frequently created by the deformation and stretching of ductile, non-metallic particles during manufacturing processes like rolling.
Elongation – It is a term used in mechanical testing to describe the quantity of extension of a test piece when stressed. It is expressed in units of length or as strain (percent change in length). Quantitative value describing the length increase of the gauge length of a tensile-test bar because of the deformation up to and including the fracture process. It is to be noted that elongation (expressed as length or strain) is not an inherent material property but depends on the dimension of the sample tested as well as whether it is measured under load, such as with a laser extensometer, or after fracture, normally after manually remating the fracture surfaces in a fixture.
Elongation at break – It is the elongation recorded at the moment of rupture of the sample. It is frequently expressed as a percentage of the original length.
Elongation curve – it is frequently called a load-elongation curve or stress-strain curve. It is a graphical representation of how a material deforms when pulled by a tensile force. It plots the quantity of stretch or extension (elongation) against the applied pulling force, helping engineers determine a material’s ductility, strength, and elasticity. The curve is highly specific to the material being tested and can be broken down into three main phases namely elastic region (linear phase), plastic region (curved phase), and necking and fracture point (end of curve).
Elongation forging – It is normally known as drawing out or cogging. It is a metalworking process which reduces the cross-sectional area of a work-piece while increasing its length. As a type of open-die forging, this technique involves applying compressive force, using hammers or presses, perpendicular to the longitudinal axis of the work-piece, frequently while rotating or moving it through the dies. Elongation forging is a plastic deformation process where metal is pushed lengthwise, refining the internal grain structure.
Elongation, percent – it is the extension of a uniform section of a sample expressed as a percentage of the original gauge length calculated by the formula percent elongation = [(Lx- Lo)/Lo) x 100], where ‘Lo’ is the original gauge length and ‘Lx’ is the final gauge length.
Elution volume – It is the volume of mobile phase needed to elute an analyte from a chromatographic system, which is proportional to the partition coefficient (P) and related to the volumes of the stationary and mobile phases.
Elutriation – It is a process for separating particles based on their size, shape and density, using a stream of gas or liquid flowing in a direction normally opposite to the direction of sedimentation. This method is mainly used for particles smaller than 1 micro-meter. The smaller or lighter particles rise to the top (overflow) because their terminal sedimentation velocities are lower than the velocity of the rising fluid. It is a test for particle size in which the speed of a liquid or gas is used to suspend particles of a desired size, with larger sizes settling for removal and weighing, while smaller sizes are removed, collected, and weighed at certain time intervals.
Eluvial deposit – It is also known as eluvium. Eluvial deposits are geological deposits and soils formed by the in-situ weathering of rocks, sometimes combined with gravitational movement or accumulation. These deposits are the remaining materials after the removal of soluble elements or lower density materials through processes like leaching or winnowing. Eluvial deposits can be enriched with economic minerals like tungsten and gold in placer deposits.
Email – It is short for electronic mail. It is a digital method of exchanging messages, files, and data between people or systems over the internet or private networks. It acts as both a communication system and individual messages, allowing for fast, asynchronous, and cost-effective communication across different digital devices.
Email address – It is also called email ID. It is a unique string of characters used to identify a specific electronic mailbox, acting as a digital address for sending and receiving messages over the internet. It consists of a user-defined local part, an ‘@’ symbol, and a domain name (e.g., username@example.com).
Email attachment – It is a computer file sent along with an email message. One or more files can be attached to any email message, and be sent along with it to the recipient. This is typically used as a simple method to share documents and images.
EM algorithm – It is defined as a numerical technique used for obtaining maximum likelihood estimates (MLEs) in standard incomplete data problems by iterating between an E-step (expectation step), which computes the expected complete log-likelihood, and an M-step (ma, which maximizes this expected log-likelihood based on the observed data.
E matrix – It is also called elasticity matrix. It is a fundamental constitutive matrix used in solid mechanics and the finite element method (FEM). It relates stress to strain in elastic materials, defining how a material deforms under applied loads based on its Young’s modulus and Poisson’s ratio.
Embankment – It is an artificially raised mound of earth, rock, or aggregate. It is mainly constructed to raise the grade of a roadway or railway above surrounding ground levels, to support a canal, or to serve as a barrier to contain and hold back water.
Embankment construction – It is the process of building a stable embankment which is focus on preventing slope failure, minimizing long-term settling, and ensuring adequate drainage. The stages in the construction process are site preparation, material selection, compaction, and staged construction. Key engineering considerations are settlement analysis, slope stability, and drainage.
Embankment fill – It refers to the earthen materials, such as soil, rock, or aggregate, used to construct a raised mound or ridge. It is systematically placed and compacted to elevate the grade for roadways, railways, or to act as a barrier against water.
Embankment load – It is the downward vertical force exerted by a raised earthen structure (like a highway, railway, or dam) onto its underlying foundation soil. Calculated as the product of the fill material’s unit weight and the embankment’s height, it governs foundation settlement, bearing capacity, and overall structural stability.
Embankment settlement – It is the total vertical downward displacement of a raised earth structure (like a road, railway, or dam) and its underlying soil. It is caused by the weight of the fill material and applied loads, which compress the ground and fill.
Embankment slope – It is the inclined outer surface of a raised earthwork structure (like a highway, railway, or dam). It is typically defined as a ratio of horizontal distance to vertical rise (e.g., 2:1) or as an angle of inclination to prevent soil erosion and structural failure.
Embankment stability – it is a structure’s ability to resist downslope gravitational movement and maintain structural integrity under different loads and environmental conditions. It is an important civil engineering concept ensuring that elevated earthworks, such as dams, highways, and railways, do not fail or collapse.
Embeddability – It normally refers to a material’s ability to safely absorb and envelop microscopic debris or foreign particles without causing surface damage to rotating parts. It is a critical design property mainly used in bearing alloys, machine design, and software systems. It is the ability of a bearing material to embed harmful foreign particles and reduce their tendency to cause scoring or abrasion.
Embedded abrasive – It consists of fragments of abrasive particles forced into the surface of a work-piece during grinding, abrasion, or polishing.
Embedded applications – These applications refer to specialized software systems designed to perform specific tasks within larger systems, often built on operating systems such as ‘real-time operating systems’ (RTOS) for critical timing or variants of Linux for less time-sensitive operations. These applications can either be real-time, where timing is important, or non-real-time, depending on the requirements of the system.
Embedded architecture – It is a structured abstraction of a specialized computing system which integrates hardware and software. It defines how components, such as micro-controllers, memory, and interfaces, interact to perform dedicated, real-time tasks, serving as the master blueprint before detailed hardware or software implementation begins. A robust embedded architecture organizes the system into specific conceptual layers to ensure efficiency, reliability, and low power consumption.
Embedded assembler – It is a feature in certain compilers which allows the inclusion of assembly code within a C-program, enabling low-level system control and performance optimization, particularly for tasks like direct stack manipulation and timing-critical routines.
Embedded board – It is a specialized circuit board designed to host a master processor, memory, and I/O (input / output) interfaces to perform a single, dedicated function within a larger mechanical or electronic system. Unlike standard personal computers (PCs), they prioritize long-term stability, real-time responsiveness, and compact, application-specific footprints. Embedded boards are foundational to hardware and firmware engineering, driving everything from smart appliances to industrial robotics and automotive electronic control units (ECUs).
Embedded capsule – It can refer to different concepts depending on the field. Very frequently, it describes a specialized vessel used in materials science for self-healing products. In microscopy, it consists of small plastic, gelatin, or polyethylene moulds used in laboratory settings to embed samples. In artificial intelligence and deep learning, it is a hybrid neural network architecture which integrates ‘capsule layers’ (designed to recognize spatial hierarchies and object orientation) into deeper, traditional convolutional networks.
Embedded control unit – It is a specialized, dedicated computing system (hardware + software) designed to manage, monitor, or regulate specific functions within a larger machine. It processes input from sensors and controls actuators in real-time, functioning within dedicated applications. These units operate independently to execute specific, repetitive control tasks. Unlike general-purpose computers, they are optimized for efficiency, cost, and reliability in a particular application. They typically consist of a micro-controller or micro-processor, memory, input/output (I/O) interfaces, and peripheral components (sensors / actuators).
Embedded device – It is a specialized computing system built into a larger mechanical or electrical system to perform a single, dedicated function. Unlike general-purpose computers (like laptops or smartphones) designed for several tasks, embedded devices are highly optimized, task-specific, and invisible to the user.
Embedded fibre – It refers to the incorporation of continuous or discontinuous fibres within a solid base material (matrix) to form a stronger, composite material. It is widely used to improve structural integrity, and add sensing capabilities.
Embedded Linux – It is a customized version of the Linux operating system designed for embedded systems, comprising major components such as a boot loader, Linux kernel, root file system, and cross-tool chain, all derived from freely available source code.
Embedded operating system – It is the common operating environment which supports embedded software. It can be a highly tailored version of a general-purpose operating system, or written solely for the purpose of embedded system operations.
Embedded processor – It is a specialized microchip designed to perform dedicated functions within a larger mechanical or electrical system. Unlike the general-purpose processors in personal computers (PCs), they are optimized for specific tasks, power efficiency, and physical size rather than running varied software.
Embedded reinforcement bar – It refers to ribbed steel or composite bars cast directly inside concrete structures. Since concrete is strong under compression but weak under tension, this embedded steel acts as a composite material, absorbing bending and pulling stresses to prevent structural failure.
Embedded sensor – It is a sensing device integrated directly into a larger piece of hardware, software, or material to monitor physical conditions in real-time. It acts as the ‘eyes and ears’ of an embedded system, capturing data which a microcontroller uses to make automated decisions and interact with the environment. Embedded sensors differ from traditional, standalone sensors since they are deeply integrated into a host architecture.
Embedded software – It is a firmware component of a micro-processor-controlled system.
Embedded system – It is a specialized computer system which controls a device or system, with no or a minimal user interface. It is a combination of a computer processor, computer memory, and input / output peripheral devices, i.e., it has a dedicated function within a larger mechanical or electronic system.
Embedded system architecture – It is a structured plan or blueprint which defines the hardware and software components of a specialized computing device. It abstracts the system by representing functions as interacting blocks, prioritizing the relationships, behaviours, and specifications needed to operate within a larger mechanical or electrical host.
Embedded system design – It is the process of developing specialized computing hardware and software to perform dedicated functions within a larger mechanical or electrical system. It merges electronic components and code to create efficient, low-power devices tailored for specific applications.
Embedded system model – It defines the architectural representation of a purpose-built computing device, integrating specialized hardware, system software, and application firmware, designed to execute dedicated functions within a larger mechanical or electrical system. These models typically break the architecture down into distinct operational layers to help engineers visualize and manage complex component interactions.
Embedding dimension – It is the length of the numerical vector which represents a piece of data (such as a word, image, or document) in machine learning. It determines the number of numerical features used to capture the data’s semantic meaning, relationships, and attributes in a continuous vector space.
Embedding distortion – It is a mathematical metric which measures how much the distances or relationships between data points change when they are transformed from one space to another (e.g., from an original dataset into a lower-dimensional vector representation). Lower distortion means better, more accurate preservation of the original data.
Embedding function – It is a process which translates complex, high-dimensional data (such as text, images, or audio) into dense numerical vectors. It maps these objects into a lower-dimensional space so that items with similar meanings or properties are grouped closely together mathematically.
Embedding process – It is a technique used to map discrete, high-dimensional data (such as words, images, or categories) into continuous, lower-dimensional vectors while preserving their underlying meaning or structural relationships.
Embedment – It refers to the act, process, or state of firmly fixing, enclosing, or integrating something deeply within a surrounding mass, system, or matrix. It is utilized across different fields to describe physical placement, digital integration, structural design, or data representation.
Embodied carbon – It refers to the total greenhouse gas emissions generated during the entire lifecycle of a product or material. It includes emissions from raw material extraction, manufacturing, transportation, installation, maintenance, and final disposal.
Embodied energy – It is the total sum of all the energy needed to produce a product, service, or structure across its entire lifecycle. It is a ‘hidden’ cost which includes raw material extraction, manufacturing, transportation, installation, and final disposal.
Embodied water – It is frequently called virtual water. It is the total volume of freshwater consumed or polluted across a product’s entire supply chain. This includes the water needed to extract, process, manufacture, and transport raw materials, as well as the water used directly in final assembly and disposal.
Embodiment design – It is the stage after conceptual design in the engineering design process in which the features of a part and their arrangement and connectivity are determined. Qualitative reasoning based on fundamental principles is used to make decisions between alternatives. A sketch of the part and preliminary decisions on material selection and manufacturing methods are made in this stage. Final dimensions and tolerances are not determined in this stage. It is also known as configuration design.
Embossed-projection technique – It is a specialized resistance welding technique used to join metal sheets by pre-forming a small raised protrusion (the projection or boss) on one of the components. The technique is used to create highly localized joints in sheet-to-sheet applications, allowing for precise welding of components.
Embossed projection welding – It is a resistance welding technique where projections, or raised areas, are created on one workpiece before welding, concentrating current flow and heat at those specific points. These projections can be embossed, dimpled, or otherwise formed on the base material to achieve localized welding.
Embossing – It is a technique which is used to create depressions of a specific pattern in plastic film and sheeting. Such embossing in the form of surface patterns can be achieved on moulded parts by the treatment of the mould surface with photo-engraving or another process. It is also raising a design in relief against a surface.
Embossing die – It is a die used for producing embossed designs.
Embossment – It is a raised, three-dimensional design, pattern, or texture pressed into a surface, such as paper, leather, or metal. It is the physical result of the embossing process, which uses pressure and sometimes heat with specialized metal dies to elevate areas of a material above the standard background.
Embrittlement – It is the severe loss of ductility or toughness or both, of a material, normally a metal or alloy. Several forms of embrittlement can lead to brittle fracture. Several forms can occur during thermal treatment or high-temperature service (thermally induced embrittlement). Some of these forms of embrittlement, which affect steels, include blue brittleness, 475 deg C embrittlement, quench-age embrittlement, sigma-phase embrittlement, strain-age embrittlement, temper embrittlement, tempered martensite embrittlement, and thermal embrittlement. In addition, steels and other metals and alloys can be embrittled by environmental conditions (environmentally assisted embrittlement). The forms of environmental embrittlement include acid embrittlement, caustic embrittlement, corrosion embrittlement, creep-rupture embrittlement, hydrogen embrittlement, liquid metal embrittlement, neutron embrittlement, solder embrittlement, solid metal embrittlement, and stress-corrosion cracking.
Embrittlement, 475 deg C – It is the embrittlement of stainless steels upon extended exposure to temperatures between 400 deg C and 510 deg C. This type of embrittlement is caused by fine, chromium-rich precipitates which segregate at grain boundaries. Time at temperature directly influences the quantity of segregation. Grain-boundary segregation of the chromium-rich precipitates increases strength and hardness, decreases ductility and toughness, and changes corrosion resistance. This type of embrittlement can be reversed by heating above the precipitation range.
Embroidery technology – It is a specialized textile manufacturing method which uses computer-controlled machines to stitch fibres, wires, or conductive yarns onto a base material. It bridges ancient craftsmanship with digital engineering, allowing engineers to create intricate, programmable geometries for smart textiles, wearable electronics.
Emerged structure – It typically refers to a system or physical construction which rises above a reference baseline (such as a mean sea level or a foundation plane).
Emergency – It is a non-routine situation which necessitates prompt action, primarily to mitigate a hazard or adverse consequences for human life and health, property, and the environment.
Emergency action plan – It is a written document which defines specific procedures to facilitate and organize management / employee actions during work-place emergencies. It ensures safety by reducing injuries and structural damage, ensuring a swift, coordinated response to incidents like fires, explosions, or natural disasters
Emergency activation cord – It is a specially coated cord running parallel to the conveyor system, deployable in emergencies to swiftly halt conveyor operations, frequently paired with an emergency stop switch.
Emergency channel – It refers to a dedicated, high-priority communication pathway or structural flow path. It ensures life-safety, reliability, and network continuity during extreme crises or system failures. In telecommunications and systems engineering, emergency channel is a designated communication pathway (e.g., radio frequency, network slice, or satellite link) reserved for crisis coordination when main networks fail. In structural and civil engineering, emergency channel is a structural steel profile (frequently U-shaped or C-shaped) utilized in frameworks, masonry support systems, or load-bearing reinforcements. In nuclear engineering, emergency channel is a specialized, independent measurement pathway, such as a neutron flux channel, which functions independently of external power grids. In software and network architecture, emergency channel is an isolated data pipe or message queue priority used to route high-severity alerts (such as a fire alarm activation or severe weather warning). The core engineering needs for emergency channel is high reliability, redundancy, and prioritization.
Emergency circumstance – It is an unexpected event which causes or poses an immediate risk of severe harm to life, health, infrastructure, or the environment. These situations demand urgent, non-standard intervention and rapid decision-making to prevent escalation.
Emergency core cooling system – It comprises a series of systems which are designed to safely shut down a nuclear reactor during accident conditions. Under normal conditions, heat is removed from a nuclear reactor by condensing steam after it passes through the turbine. In a boiling water reactor, condensed steam (water) is fed back into the reactor. In a pressurized water reactor, it is fed back through the heat.
Emergency core cooling water – It refers to the sub-cooled water injected into the core to prevent overheating during emergency core cooling (ECC) scenarios, facilitating heat removal through condensation and ensuring fast water delivery under critical conditions.
Emergency demand – It refers to the sudden, critical requirement for resources, energy, or structural capacity to ensure safety or prevent system failure. It is the forecasted quantity and type of critical materials (e.g., medical supplies, water, heavy machinery) needed to sustain life, restore infrastructure, or mitigate disasters.
Emergency demand response – It is a grid management strategy where utility organizations incentivize or mandate consumers to reduce or shift their electricity usage during sudden crises (e.g., equipment failure, extreme weather). It helps balance supply and demand instantly to avoid blackouts, grid instability, or widespread load shedding.
Emergency demand response programme – It is a utility grid reliability strategy. It provides financial incentives to commercial, industrial, and residential customers to temporarily curtail electricity use or activate backup generators during critical contingencies (e.g., severe capacity shortfalls, extreme weather) to avoid rolling blackouts.
Emergency disconnect – It is a fail-safe system or switch designed to instantly and safely sever a connection or shut down power to an entire system during a crisis. It protects operators, first responders, and equipment from hazards like electrocution, fire, or catastrophic pressure loss.
Emergency equipment – It refers to designated devices, safety systems, and specialized tools designed to mitigate hazards, protect personnel, and safely shut down processes during an abnormal event. This encompasses both life-preserving medical / safety gear (e.g., eyewash stations) and critical hardware designed for safe facility operation (e.g., backup generators, emergency-stops).
Emergency generator – It is an independent, legally mandated backup power system. It automatically activates during main grid failures to supply power exclusively to critical life-safety and operational loads. It is integrated with an ‘automatic transfer switch’ (ATS) to detect grid outages and safely start, isolate, and connect to loads within 10 seconds to 15 seconds.
Emergency halt mechanism – It is a safety feature enabling the immediate cessation of conveyor operations in emergency scenarios, necessitating regular tests and inspections to ensure continual reliability.
Emergency maintenance – It is the maintenance which is taken for equipment restoration during an emergency. It is carried out as fast as possible in order to bring a failed equipment or facility to a safe and operationally efficient condition.
Emergency management – It is the organization and management of resources and responsibilities for addressing all aspects of emergencies, in particular preparedness, response and rehabilitation.
Emergency plan – It is detailed procedures for responding to an emergency such as fire, explosion, chemical spill, or an uncontrolled release of gas or energy. Emergency plan is a description of the objectives, policy, and concept of operations for the response to an emergency and of the structure, authorities and responsibilities for a systematic, coordinated and effective response. Emergency plan minimizes the effects of a disaster.
Emergency plume gamma monitoring system – It is a site boundary system for monitoring any airbourne radioactivity released from a nuclear site.
Emergency power – It refers to the power supply which is automatically activated to ensure life safety during electrical power interruptions. It typically supports systems such as lighting, fire detection, and elevators, and is normally designed to transfer power within 10 seconds of a service failure. In governance, emergency power describes the special, extraordinary authority granted to a manager or organizational head during an urgent crisis.
Emergency power supply system – It is an independent backup source of electrical power. Engineered to activate automatically upon main grid failure, it protects life and property by supporting critical loads, such as life-sustaining medical equipment, fire pumps, and emergency lighting, typically restoring power within 10 seconds.
Emergency power system – It is an independent, backup power source designed to automatically provide electrical power within 10 seconds of a main grid failure. Its main function is to protect human life and safety by keeping critical life-support, fire protection, and evacuation systems operational.
Emergency preparedness – It is the state of being prepared for an emergency so as to minimize the damage. It is the capability to take actions which effectively mitigate the consequences of an emergency for human life and health, property, and the environment.
Emergency procedures – These are a set of instructions describing in detail the actions to be taken by emergency workers in an emergency.
Emergency pull cord – It is a cord which runs alongside the conveyor system and can be deployed to stop the conveyor for emergencies and malfunctions.
Emergency pump – It is a redundant or backup mechanical device designed to operate during system failures, power outages, or critical contingencies. It prevents critical equipment damage or sustains life-safety operations, such as fire suppression or bearing lubrication, when main systems fail.
Emergency reference level – It consists of one of a dual set of doses likely to be averted by the introduction of counter-measures to protect the public from ionizing radiation after a nuclear or other serious accident.
Emergency rescue – It is the systematic process and use of specialized equipment to safely extract individuals from hazardous or confined environments. It relies on data-driven risk management, structural analysis, and pre-defined protocols to mitigate harm to life, property, and critical infrastructure.
Emergency response – It is the immediate, systematic action taken to manage unexpected, dangerous events (natural disasters, accidents, or health crises). It prioritizes protecting life first, then property and the environment through rapid mobilization, evacuation, and containment to prevent crises from becoming disasters.
Emergency response service – It is a systematic framework of data-driven protocols, technologies, and technical advisory teams mobilized during disasters, structural failures, or industrial accidents. Its core objective is to mitigate immediate threats to life, critical infrastructure, and the environment.
Emergency response team – It is a designated group of employees or personnel trained to immediately identify, manage, and mitigate onsite emergencies. They act as the first line of defense to ensure safety, minimize damage, and facilitate evacuation or medical assistance before professional emergency services arrive.
Emergency room – It is a specialized facility which provides immediate, unscheduled acute care for life-threatening conditions and severe injuries. In systems engineering, it is defined as a complex, highly variable operational node characterized by process flow optimization, resource allocation, queuing theory, and real-time decision-making. Emergency room (ER) is a dynamic, high-stress processing system. Engineers view the emergency room through the lens of process flow, capacity management, and constraint mitigation.
Emergency sealant injection (fitting) – For obtaining tight shut off in an emergency situation, a sealant can be injected into a specially designed groove in the seat rings and / or in the stem seal pockets. It is normally used for the majority of the ball valves and gate valves.
Emergency services – These are the critical systems, infrastructure, and first-response networks deployed to mitigate dangers to life, property, and the environment. This spans safety organizations, rapid-repair engineering for critical infrastructure, and specialized communication protocols for dispatching emergency personnel.
Emergency shutdown – It is a safety system designed to quickly and safely stop a process or equipment in response to a hazardous situation, minimizing potential damage or injury. It is a critical component of safety in high-risk industries and other environments with explosion risks.
Emergency shutdown procedure – It is a predefined plan of actions to be taken in response to a critical event or emergency situation, designed to minimize the potential for harm and prevent escalation of the event. It outlines the steps to stop operations, isolate hazardous areas, and ensure the safety of personnel and equipment.
Emergency shutdown system – It is a valve or a system of valves which, when activated, initiate a shutdown of the plant, process, or platform they are tied to.
Emergency shutdown switch – It is an electrical mechanism strategically placed to instantaneously cease conveyor functions during emergency situations, typically used alongside an emergency activation cord.
Emergency shutdown system – It is an automated safety mechanism designed to immediately halt or isolate hazardous industrial processes to prevent catastrophes like fires, explosions, or hazardous material releases. By monitoring sensors for anomalies (pressure / temp spikes), it triggers fail-safe actions like closing valves and isolating power to protect personnel and equipment.
Emergency shutdown valve – It is a valve which is capable of adequately blocking the flow of fluid within the pipeline at the point at which it is incorporated. In the absence of a definition, ‘adequate’ is taken to mean sufficient for a particular purpose. Minor internal leakage past the emergency shutdown valve can be accepted providing it does not represent a threat to the safety. The rate of leakage is to be based on the installation’s ability to control safely the hazards produced by such a leak.
Emergency stop – It is a mandatory safety mechanism designed to immediately halt hazardous machine motion or process, typically triggered by a single human action. It features a prominent red mushroom-head button on a yellow background, using a self-latching mechanism which needs manual reset.
Emergency stop switch – It is a fail-safe, manually activated control device designed to immediately halt machinery, equipment, or process during hazardous situations. As a last line of defense, it cuts power through a, typically red, mushroom-head button to prevent injury or damage, conforming to standards like International Organization for Standardization standard ISO 13850.
Emergency switch – It is a fail-safe control mechanism designed to instantly shut down machinery or cut off electrical power during urgent situations. Triggered by a single human action, it prevents accidents, protects operators, and averts escalating hazards.
Emergency switchboard – It is a critical electrical distribution board designed to automatically supply power to essential safety services (like emergency lighting, communication, and alarms) if the main electrical system fails. It is mainly fed by a backup generator or battery source.
Emerging contaminant removal – It is the process of eliminating recently identified or unregulated pollutants from water and wastewater. Since standard facilities are frequently ineffective, engineers use advanced physicochemical and biological methods to target these trace-level, persistent chemicals.
Emerging economy – It is a developing nation transitioning toward a more advanced, industrialized, and technologically sophisticated state. These economies feature high GDP (gross domestic product) growth, expanding middle classes, and growing global integration, but frequently face elevated institutional and financial volatility compared to developed nations.
Emerging feedstock – It refers to a next-generation raw material like captured carbon, used in biorefineries chemical plants. Feedstock engineering involves optimizing these materials’ chemical, and physical traits to maximize yield, process efficiency, and sustainability in manufacturing bio-based fuels and chemicals.
Emerging process – It refers to next-generation techniques designed to decarbonize, reduce energy consumption, or fabricate complex parts. These innovations pivot away from traditional, carbon-heavy methods in favour of technologies like hydrogen reduction, additive manufacturing, and closed-loop metal recycling. It is also a non-linear phase of change within a system where micro-level components reconfigure into new macro-level structures, producing unpredictable properties. Unlike traditional linear development, it involves rapid, disruptive transitions often driven by positive feedback loops.
Emerging technologies – These are new or rapidly evolving technologies which are still largely unrealized, meaning their full potential and impact are not yet fully understood or realized. These technologies are frequently perceived as having the potential to significantly change the status quo, impacting society, economy, and various sectors. They can include both new technologies and older ones finding new applications.
Emerging topologies – These refer to the development of new, optimized structural or electrical configurations which arise dynamically from specific algorithmic constraints, loads, or performance goals.
Emerging trend – It is a newly introduced or rapidly growing shift in technology, materials, or methodology. These developments reshape how engineers design, build, and operate systems, driven by digital transformation, sustainability goals, and market demands.
Emergy – It is an alternative to market evaluation for determining the net value of environmental projects to human society and is the common denominator used to express the value of environmental and economic work. This method is not normally met in economics but rather in ecological engineering.
Emery – It is naturally occurring abrasive containing 57 % to 75 % aluminum oxide and a remainder of iron oxide and impurities.
Emission – It is the release or discharge of a substance (like pollutants or exhaust) or energy (such as radiation or electrons) from a source into an environment or medium.
Emission band – It is a specific continuous range of photon energies (or wave-lengths) emitted by a material when its electrons transition from a higher energy state (the conduction band or localized defect states) to a lower energy state (the valence band).
Emission coefficient – It refers to a parameter used in the emission dispatch problem, representing the quantity of emissions produced per unit of power generation by a generating unit, typically formulated as a quadratic function.
Emission colour – It defines the specific wave-length of electro-magnetic radiation, or light, emitted by a material when it releases energy. In engineering, it refers to the precise, tailored light output used to drive technologies like light-emitting diodes (LEDs), lasers, and optical sensors through electron transitions or thermal radiation.
Emission control – It is the design and application of technologies, processes, and strategies to minimize the release of harmful pollutants and greenhouse gases from combustion engines, power plants, and industrial facilities into the atmosphere.
Emission cross-section – It is a fundamental quantum property quantifying a material’s probability of emitting a photon at a given wave-length. Measured in area (e.g., square centi-meter), it characterizes how efficiently an excited electron or ion can emit light. It the measure related to the emission properties of a material, specifically at the peak-emission wavelength.
Emission factor – It is the relationship between the quantity of pollution produced and the quantity of raw material processed, e.g., an emission factor for a blast furnace making iron is the number of kilograms of particulates per ton of raw materials.
Emission footprint – It quantifies the total release of pollutants or greenhouse gases (GHGs) into the environment. It evaluates these impacts across the entire life cycle of a process, product, or facility, from raw material extraction and manufacturing to use and final disposal. Engineers rely on standardized metrics to track and minimize these releases, ensuring processes comply with environmental regulations and sustainability goals.
Emission from biofuels – These emissions are analyzed through life cycle assessment (LCA), factoring in carbon di-oxide (CO2) absorbed during plant growth alongside greenhouse gases (GHGs) and pollutants released during farming, processing, and tailpipe combustion. Understanding biofuel emissions needs looking at both the chemical engineering and life-cycle perspectives.
Emission gas – It is the discharge of vapours or gaseous by-products into the atmosphere. These emissions are normally categorized by their environmental impact, their source, and whether they are the result of natural processes or industrial and mechanical combustion. Engineers strictly manage and monitor these gases to meet environmental regulations and optimize system efficiency.
Emission intensity – It is a metric which measures the quantity of greenhouse gases (GHGs) released relative to a specific unit of activity, economic output, or physical production. It decouples the scale of an operation from its environmental impact, making it ideal for evaluating efficiency and tracking improvements over time. This metric is expressed as a ratio given by emission intensity = total emissions (carbon di-oxide equivalent) / unit of activity or output.
Emission inventory – It consists of a listing by source of the amount of air pollutant discharge into the atmosphere of a community is known as emission inventory. It is used to establish emission standards.
Emission legislation – It dictates the strict legal limits on pollutants, e.g., nitrogen oxides (NOx), carbon mono-oxides (CO), and particulates, released into the atmosphere by vehicles, and industry. It serves as the foundational boundary condition, needing the design of power-trains, aftertreatment systems, and control software which meet these rigorous compliance standards while optimizing performance.
Emission lines – These are spectral lines resulting from emission of electro-magnetic radiation by atoms, ions, or molecules during changes from excited states to states of lower energy.
Emission measurement – It is the systematic process of quantifying the release of pollutants, greenhouse gases, or electro-magnetic interference into the environment. It utilizes specialized sensors, analyzers, and test cycles to assess compliance with regulations and optimize system efficiency.
Emission of electro-magnetic radiation – It is the creation of radiant energy in matter, resulting in a corresponding decrease in the energy of the emitting system.
Emission peak – It refers to the maximum magnitude, intensity, or wavelength of a substance or signal released into the environment or system. In case of electromagnetics and radio frequency, emission peak is the maximum amplitude of an electromagnetic signal emitted by a device. In electro-magnetic compatibility (EMC) / electro-magnetic interference (EMI) testing, it is the highest power or voltage spike across a frequency spectrum. In case of physics and photonics, emission peak is the specific wave-length where a light source, laser, or radiating body releases maximum energy or exhibits peak spectral intensity. In case of energy and sustainability, emission peak is the historical or projected point in time when greenhouse gas or carbon emissions reach their absolute maximum level before beginning a downward trend.
Emission reduction unit – In environmental engineering and carbon markets, emission reduction unit (ERU) is a tradeable compliance credit representing the reduction or removal of 1 metric ton of carbon di-oxide equivalent (CO2e) emissions. These credits are typically generated through certified sustainability or operational interventions.
Emission regulations – These are legally enforceable rules which establish the maximum allowable limits for specific pollutants released into the atmosphere by vehicles, power plants, and industrial facilities. They drive the design, development, and testing of exhaust after-treatment systems, combustion efficiency, and alternative power-trains to ensure strict compliance.
Emission requirements – It is the process of translating global or regional environmental regulations into strict, quantifiable technical specifications. It dictates the maximum allowable limits for pollutants like nitrogen oxides (NOx), carbon di oxide (CO2), particulate matter (PM), and unburned hydro-carbons, and outlines test cycles, durability needs, and diagnostic protocols for a product. This important phase in the product development lifecycle bridges the gap between environmental law and the physical design of engines, vehicles, or industrial systems.
Emissions – These are substances released into the air and are measured by their concentrations, or parts per million, in the atmosphere. Technically, an emission is anything which is being released out into the open. But more frequently it refers to gases being released into the air, like greenhouse gasses or emissions from power plants and factories. The main greenhouse gases are water vapour, carbon di-oxide, methane, nitrous oxide, hydro-fluoro-carbons, per-fluoro-carbons and sulphur hexa-fluoride.
Emissions offsets – It consists of emissions reductions from one set of actions which are used to offset emission caused by another set of actions.
Emission source – It is a physical equipment, process, or facility which releases pollutants or greenhouse gases into the environment. These origins are defined by specific parameters, such as emission rate, exit velocity, temperature, and physical dimensions, which are used to model environmental dispersion and ensure regulatory compliance.
Emission spectrometer – It is an instrument which measures percent concentrations of elements in samples of metals and other materials. When the sample is vapourized by an electric spark or arc, the characteristic wave-lengths of light emitted by each element are measured with a diffraction grating and an array of photo-detectors or photographic plates.
Emission spectroscopy – It is the branch of spectroscopy treating the theory, interpretation, and application of spectra originating in the emission of electro-magnetic radiation by atoms, ions, radicals, and molecules.
Emission spectrum – It is an electro-magnetic spectrum which is produced when radiation from an emitting source, excited by any of different forms of energy, is dispersed.
Emissions reduction unit – It is equal to one ton of carbon di-oxide emissions reduced or sequestered arising from a Joint Implementation (defined in Article 6 of the Kyoto Protocol) project calculated by using ‘global warming potential’ (GWP).
Emissions requirement – It refers to the systematic process of identifying, analyzing, and documenting legally enforceable or performance-based limits on pollutants and energy waste released by a product, system, or facility. It translates high-level environmental regulations into measurable technical specifications for design teams.
Emission standards – These are the regulatory requirements governing air pollutants which are released into the atmosphere. Emission standards set quantitative limits on the permissible quantity of specific air pollutants which can be released from specific sources over specific time-frames. These standards are normally designed to achieve air quality standards and to protect human life. Several standards use emission factors in their prescription and hence do not impose absolute limits on the emissions.
Emission test – It evaluates the release of energy, pollutants, or physical waves from a material, device, or system. It mainly ensures compliance with environmental, regulatory, or safety standards to minimize environmental pollution, protect public health, and prevent electromagnetic or structural failures.
Emissions trading – It is one of the three Kyoto mechanisms, by which an Annexure I party can transfer Kyoto Protocol units to or acquire units from another Annexure I party. It is a market-based approach to achieving environmental objectives which allows, those reducing green-house gas emissions below what is needed, to use or trade the excess reductions to offset emissions at another source inside or outside the country. In general, trading can occur at the intra-company, domestic, and international levels. An emission trading under Article 17 of the Kyoto Protocol is a tradable quota system based on the assigned amounts calculated from the emission reduction and limitation commitments listed in Annexure B of the Protocol.
Emissions trading scheme – It is a market-based ‘cap-and-trade’ regulatory mechanism. It defines an absolute limit (cap) on total greenhouse gas or pollutant emissions and distributes corresponding tradeable allowances to participating industrial or corporate entities, allowing the market to determine the price of emissions.
Emission wave-length – It refers to the specific wave-length of electro-magnetic radiation released by a material or object when it undergoes a transition from an energetic, excited state to a lower or ground state.
Emissive layer – It is the active core of optoelectronic devices, such as OLEDs (organic light-emitting diodes), where electrical energy is directly converted into visible photons. It is sandwiched between charge transport layers and is where injected electrons and holes recombine to emit light.
Emissive material – It refers to any substance evaluated for its ability to emit electromagnetic radiation (such as light or heat). Emissivity is quantified by a dimensionless coefficient, which ranges from ‘0’ (a perfect reflector) to ‘1’ (a perfect emitter, or blackbody).
Emissivity – It is the ratio of the quantity of energy or of energetic particles radiated from a unit area of a surface to the quantity radiated from a unit area of an ideal under the same conditions.
Emitted components – These refer to the radiation emitted by the atmosphere as a function of temperature at different altitudes, which integrates contributions from different altitudes along the view path. This results in a spectral distribution which represents a mixture of blackbodies over a range of temperatures.
Emitted light – It is the process by which a material transforms an external energy source (electrical, thermal, or optical) into electro-magnetic radiation visible to the human eye, normally between 380 nano-meters to 750 nano-meters. This process is governed by the principles of quantum mechanics.
Emitted radiance – It is the rate at which electromagnetic energy is emitted by a surface, per unit of emitting surface area, per unit of solid angle (watts per square meter per steradian). It measures the angular brightness of an emitting source, defining how much radiant power travels in a specific direction.
Emitted wave – It refers to energy, either electromagnetic or mechanical, radiated outward from a specific source. These waves (like radio, light, or acoustic emissions) transmit power, momentum, and information through space or a medium without transporting physical matter.
Emitter amplifier – It is a fundamental electronic circuit utilizing a ‘bipolar junction transistor’ (BJT). It takes a weak input signal applied to the base and magnifies it to produce a powerful, inverted output signal at the collector. In this configuration, the emitter terminal serves as the shared reference point (or ground) for both the input and output circuits.
Emitter circuit – it refers to the portion of a transistor circuit associated with the emitter terminal, the heavily doped region of a ‘bipolar junction transistor’ (BJT) which injects charge carriers into the base. It mainly sets up current, provides feedback, and establishes bias. Depending on the circuit topology, emitter circuit can also refer to broader configurations where the emitter acts as a reference or terminal.
Emitter-coupled logic – It is an ultrafast digital bipolar logic family. By using a differential amplifier to steer current rather than driving transistors into saturation, emitter-coupled logic (ECL) prevents charge storage delays. This allows it to achieve propagation delays under 1 nano-second, making it ideal for high-speed Ethernet and fibre optics.
Emitter-coupled logic circuit – It is a type of current mode logic which is normally used to build logic gates in which emitters of two transistors are connected to a current carrying resistor so that only one transistor works at a time. Here output of the transistor is taken from emitter instead of collector.
Emitter follower – It is a bipolar junction transistor (BJT) transistor circuit where the output is taken from the emitter and follows the input base voltage. It provides no voltage gain but offers high input impedance and low output impedance, making it ideal for impedance matching and signal buffering.]
Emitter junction – It is also called emitter-base junction. It is the semi-conductor interface within a bipolar junction transistor (BJT) which separates the emitter from the base. Its main function is to inject charge carriers (electrons or holes) into the base region when forward-biased, initiating current flow through the device. Understanding the emitter junction requires looking at its physical design, operational state, and electrical characteristics:
Emitter node – is is a component in the emitter-receiver architecture responsible for broadcasting messages, typically observations collected by a robot, to a processing unit or supervisor node for further analysis and action determination. It defines the highly-doped terminal of a transistor or an emission point for physical particles and heat.
Emitter resistance – It refers to the resistance at the emitter terminal of a bipolar junction transistor (BJT). It can be an external component used for biasing and stability, or the small intrinsic resistance inherent to the semi-conductor junction itself.
Emitter resistor – It is a passive component placed in series with the emitter terminal of a BJT (bipolar junction transistor). Its main function is to provide negative feedback, which stabilizes the transistor’s DC (direct current) operating point (biasing), prevents thermal runaway, and controls AC (alternating current) signal gain.
Emitter saturation current density (Jo) – It measures the rate of minority carrier recombination within a semiconductor’s heavily doped emitter region. It is an important metric in semi-conductor physics, particularly in photo-voltaics, where a lower ‘Jo’ value indicates a higher-quality emitter and better overall solar cell efficiency.
Emitter side – It refers to the highly doped terminal of a bipolar junction transistor (BJT) or insulated gate bipolar transistor (IGBT) designed to inject charge carriers (electrons or holes) into the adjacent base region. It acts as the main source for the device’s electrical current.
Emitter voltage – It is the electrical potential at the emitter terminal of a transistor. In bipolar junction transistors (BJTs), it acts as the main reference point for amplifying or switching signals, with the base-emitter voltage needing a 0.7 V forward bias to operate.
Emitting device – It refers to a component, system, or transducer which that converts input energy (like electrical current or thermal energy) into an output wave or particle (e.g., light, radio frequencies, heat, or electrons) to perform a specific function.
Emitting diode – It is a semiconductor device that emits visible light or infrared energy when an electric current passes through it, consisting of a p-type and n-type semi-conductor forming a p–n junction.
Emitting fabric – It integrates optical, electrical, or thermal emitters directly into woven or knitted materials. Engineered for applications like wearable displays, and thermal management, this technology combines flexible waveguides with woven structures to emit specific wavelengths without compromising textile flexibility.
Emitting laser – It is a device that generates a coherent, concentrated beam of light through the process of stimulated emission. It refers to a specific semiconductor architecture where electrical energy is converted into highly directional and mono-chromatic light.
Emitting light – It is the physical process of converting electrical, thermal, or chemical energy into visible or invisible electro-magnetic radiation (photons). This is very frequently achieved through electro-luminescence (like light-emitting diodes) or incandescence (like traditional light bulbs).
Emitting phosphor – It is an engineered luminescent material which absorbs incident energy and converts it into visible or non-visible light. It functions as a down-converter, where materials (like rare-earth doped crystals or quantum dots) are excited by external sources like UV (ultra-violet) rays or electrons to emit specific colours.
E-modulus – It is also called elastic modulus or Young’s modulus. It is a fundamental mechanical property which measures a material’s stiffness. It defines how much a material stretches or compresses under applied stress while maintaining its ability to return to its original shape.
Empirical distribution – It directly describes the observed data rather than assuming a theoretical model. It defines the probability of outcomes based strictly on experimental frequencies, where each of ‘n’ data points is assigned an equal probability of ‘1/n’.
Empirical formula – It is the simplest whole-number ratio of the atoms of each element present in a chemical compound.
Empirical growth law – It is a mathematical relationship derived from experimental observation and data fitting, rather than from first-principles theory. It describes how a specific quantity (such as crack length, or system performance) changes over time or in response to external factors, serving as a predictive tool within specific operational limits.
Empirical-mode decomposition – It is a fully data-driven, adaptive technique used to analyze non-linear and non-stationary signals. It breaks down complex datasets into a finite set of oscillatory components known as intrinsic mode functions (IMFs).
Empirical model – It is a mathematical or statistical representation of a system based entirely on observed experimental data and experience, rather than theoretical first principles. It is frequently called a black-box model since it focuses strictly on mapping inputs to outputs.
Empirical nature – It refers to an approach driven by observation, experimental data, and past success rather than purely theoretical or mathematical derivation. It emphasizes real-world testing, curve-fitting, and practical rules of thumb to solve complex problems when exact first principle theories are insufficient.
Empirical rule – It is also known as the 68 – 95 – 99.7 rule. It is a statistical guideline which describes the distribution of data in a normal distribution. It states that in a normal distribution, 99.7 % of observed data falls within three standard deviations of the mean. Specifically, 68 % of the observed data occur within one standard deviation, 95 % within two standard deviations, and 99.7 % within three standard deviations. The empirical rule is applied to anticipate probable outcomes in a normal distribution.
Empirical specification – It defines system parameters, models, or needs based on historical data, observation, and experimentation rather than purely theoretical or fundamental mathematical derivations.
Employee – Employee is a person who is on the payroll of the organization emitter. The employee has an employee number which identifies the person as an employee of the organization and who is directly supervised by a representative of the organization. Temporary or agency workers hired directly by the organization are to be considered as employees if the organization has primary responsibility for supervising their activities.
Employee engagement – It consists of the harnessing of organization members’ selves to their work roles; in engagement, people employ and express themselves physically, cognitively, and emotionally during role performances. It is translating employee potential into employee performance and organizational success. It can also a set of positive attitudes and behaviours of the employees enabling their high job performance of a kind which is in tune with the organization’s mission. It is a fundamental concept in the effort to understand and describe, both qualitatively and quantitatively, the nature of the relationship between an organization and its employees. It is a workplace approach resulting in the right conditions for all members of an organization to give their best each day, committed to their organization’s goals and values, and motivated to contribute to organizational success with an improved sense of their own well-being. There are four main sub-concepts within the term employee engagement. These are (i) ‘needs satisfying’ approach, in which engagement is the expression of one’s preferred self in task behaviours, (ii) ‘burnout antithesis’ approach, in which energy, involvement, efficacy are presented as the opposites of established ‘burnout’ concepts consisting of exhaustion, pessimism, and lack of accomplishment, (iii) satisfaction-engagement approach, in which engagement is a more technical version of job satisfaction, and (iv) the multi-dimensional approach, in which a clear distinction is maintained between job and organizational engagement, normally with the primary focus on antecedents and consequents to the role performance rather than the organizational identification.
Employee innovativeness – It consists of an employee engagement in the innovative work behaviours, which includes behaviours related to the innovation process, i.e. idea generation, idea promotion, and idea realization with the aim of producing innovations. Innovations which have to do with the implementation or adoption of the new ideas can in turn be categorized as either technological (changes in products, services, production processes) or administrative (changes in activities, social processes, structures), and as either radical or incremental, depending on the extent of their influence for existing products or processes. Employee innovativeness can thus be examined throughout the innovation process, from the initial idea generation to product development and eventually to product commercialization, or to the adoption of new processes or structures in the organization.
Employee morale – It related to how the employees feel about the organization. It is an important factor in creating a healthy work environment. Organization which has higher employee morale displays improved productivity, improved performance and creativity, reduced number of days taken for leave, higher attention to details, a safer workplace, and an increased quality of work. In addition to that, the organization has employees who arrive to work on time, communicate better, waste lesser time in gossip, have higher rate of retention, and are more creative. Moreover, employees who work with high morale develop higher rates of job satisfaction, creativeness and innovation, respect for their own job, commitment to the organization, eagerness to satisfy group objectives instead of individual objectives, and desire to improve the organizational performance.
Employee productivity – It is a measure of the quantity and quality of work done, considering the cost of the resources used. The more productive an organization is, the better is its competitive advantage, since the costs to produce its goods and services are lower. Better productivity does not necessarily mean higher production. It is perhaps fewer employees (or less money or time) is used to produce the same quantity of products or services.
Employee relations – It is a broad concept which involves maintaining a working environment which satisfies the needs of the management and the employees. An effective employee relations programme involves creating and cultivating a productive work-force. It covers all the relations between employers and employees in industry. Employee relations also include defining the scope for employee participation in management decisions which relate to health and safety, collective bargaining, communication, and conflict resolution. In the current dynamic and competitive environment, it is necessary for the organization to maintain suitable employee relations as a way of achieving sustainable competitive advantage. Employee relations have several positive effects in the organization which includes strengthening corporate communication and culture, improvements in the organizational products to the customers, providing opportunities for the training and development of the employees, and providing information to the employee based on their needs.
Employee suggestion scheme – It plays a crucial role in an organization having a desire to become more innovative. It is described as a formalized mechanism which encourages employees to contribute constructive ideas for improving the organization in which they work. It can be seen as an un-tapped reservoir of effort and knowledge which can improve organizational processes and effectiveness. Employee suggestion schemes are also sources of innovation as they promote the implementation of new routines and facilitate the improvement and refinement of existing routines. Hence, employee suggestion scheme plays a pivotal role for the organization wishing to become more innovative. New and creative ideas are essential to solve problems, economize work hours, spare the efforts of several employees, and meet their social and cultural needs. After all, untapped employee creativity is a wasted organizational resource. An effective employee suggestion scheme helps convert that waste into wealth. The employees’ suggestions create a win–win situation both for the organizational management and the employees alike. However, despite several benefits of the employee suggestion schemes, sustaining and implementing them is still a challenge for the organizational management.
Employer – Employer is a person or organization with recognized responsibilities, commitments and duties towards a worker in the employment of the person or organization by virtue of a mutually agreed relationship.
Empty mass – It is the base mass of a machine, vehicle, or structure in its fully assembled state, excluding payloads, passengers, and operational consumables like usable fuel. It is the foundation for calculating maximum load capacities and assessing overall structural performance.
Empty tank – It refers to a vessel with negligible contents. A tank is normally classified as empty if it contains a regulated substance of no more than 2.5 centimeters in depth, or less than 0.3 % to 3 % by weight of its total capacity. Even in this state, it is frequently classified as a ‘residue tank’ and is to be treated as hazardous if flammable or toxic vapours are present. As per mechanical design, an empty state is the baseline used to calculate the tare weight (the weight of the structural shell without fluid). Structural engineers evaluate the empty state for structural integrity, as it is the most vulnerable condition for wind-load uplift, buckling, and vacuum-induced implosions if venting fails. In fluid dynamics, for calculations of drainage time, an empty tank is mathematically defined when the fluid level reaches the minimum design height or drain orifice, governed by principles like Torricelli’s law.
Emulsification – It is the property of lubricating oil to get mixed with water easily. Emulsions can be oil in water emulsion or water in oil emulsion.
Emulsifiers – These are substances which allow normally unmixable liquids, such as oil and water, to blend together into a stable, smooth, and uniform mixture. By reducing interfacial tension, they create emulsions which prevent ingredients from separating.
Emulsifying agent – It is a substance which increases the stability of an emulsion.
Emulsion – It is a stable dispersion of one liquid in another, normally by means of an emulsifying agent which has affinity for both the continuous and discontinuous phases. The emulsifying agent, discontinuous phase, and continuous phase can together produce another phase which serves as an enveloping (encapsulating) protective phase around the discontinuous phase.
Emulsion calibration curve – It is the plot of a function of the relative transmittance of the photographic emulsion against a function of the exposure. The calibration curve is used in spectrographic analysis to calculate the relative intensity of a radiant source from the density of a photographically recorded image.
Emulsion cleaner – It is a cleaner consisting of organic solvents dispersed in an aqueous medium with the aid of an emulsifying agent. Majority of the emulsion cleaners include emulsifying agents, and some are aided by surfactants. Emulsion cleaners are normally used in situations where alkaline or acid cleaners are not applicable.
Emulsion cleaning – It is an industrial cleaning process which uses an organic solvent as the main active agent. The solvent is normally a hydro-carbon of distilled petroleum dispersed in water. The emulsion, which alone is potentially volatile, is suspended in a non-volatile aqueous vehicle.
Emulsion inversion – An emulsion is said to invert when, e.g., a water-in-oil emulsion changes to an oil-in-water emulsion.
Emulsion phase – It refers to the dispersed and continuous phases in an emulsion, typically consisting of two immiscible liquids where one phase, frequently an oil, is present as droplets within the other phase, normally an aqueous solution. The stability of this phase is important in industrial applications and can be affected by factors such as droplet size and the presence of surfactants.
Emulsion polymerization – It is a type of free-radical polymerization which occurs in an emulsion, typically oil-in-water, to create polymer particles dispersed in water, frequently called latex. It uses monomers, water, surfactants (soap) to stabilize particles, and water-soluble initiators to produce synthetic rubbers, coatings, and plastics.
Emulsion system – It is a thermodynamically unstable, heterogeneous mixture of at least two immiscible liquids. One of the liquids acts as a dispersed phase (small droplets), while the other acts as a continuous liquid phase. Engineered systems rely on surfactants (emulsifiers) to lower interfacial tension and achieve kinetic stability.
Enabling system – It is a supporting system which facilitates a ‘system of interest’ throughout its lifecycle, development, production, testing, deployment, or support, without being part of its direct operational function. It enables the main system to progress and function effectively, such as a training system preparing operators.
Enabling systems engineering – It is a structured, inter-disciplinary approach which facilitates the development, operation, and support of a ‘system-of-interest’ throughout its lifecycle. It involves creating the necessary processes, tools, organizational structures, and training systems, such as manufacturing, testing, or maintenance systems, which allow the main product to be developed, operated, and sustained effectively.
Enabling technology – It is a foundational innovation or tool which drives radical leaps in capability. It acts as a catalyst, making subsequent products, services, or diverse sub-technologies possible which otherwise is unattainable.
Enamel – It is essentially a glass with a low softening temperature ranging from 510 deg C to 530 deg C. It is a glass obtained by fusion at high temperature between 1,000 deg C and 1,300 deg C. Enamels normally consist of an acidic refractory material such as quartz, feldspar, clays and mica. In order to confer on enamelled parts its properties of durability, silica glass has to be modified, as it cannot be used in its original state. Its melting point is too high, its coefficient of thermal expansion is too low compared to that of steel and its adhesion to steel is zero. Hence, various additives need to be added in order to obtain enamel. Depending on the ultimate function of the enamel, various additives which can be used are pigments, opacifiers, clays or other materials to serve as deflocculants and floatation agents, which help suspend the enamel particles in an aqueous solution.
Enamel coating – It is a substantially vitreous or glassy inorganic coating bonded to the steel substrate by thermal fusion. This coating is applied for the protection of steel products from surrounding environments. This coating provides not only an aesthetic exterior but also provides outstanding engineering properties, such as mechanical strength of the enameled surface, multiplicity and stability of colour, corrosion resistance, resistance to wear and abrasion, chemical and heat resistance, resistance to thermal shock and fire, hygiene and ease of cleaning etc.
Enameled wire – It is a wire insulated with a thin flexible layer of enamel, used for electrical windings.
Enameling iron – It is a low-carbon, cold-rolled sheet steel, produced specifically for use as a base metal for porcelain enamel.
Enameling process – The enameling process involves applying and firing one or more layers of enamel on one or both sides of a suitable steel substrate. Successful enameling is characterized by (i) good adhesion of enamel to the steel, and (ii) a good surface appearance after firing of the enamel. The carbon content of the steel can hinder the process of achieving these two properties. Carbon content of steel is important for ensuring the adhesion of enamel. However, if the carbon content is too high then it can adversely affect the surface appearance of the enamel because of the release of gaseous carbon di-oxide and carbon mono-oxide produced during firing.
Enantiotropy – It is the relation of crystal forms of the same substance in which one form is stable above a certain temperature and the other form is stable below that temperature. For example, ferrite and austenite phases are enantiotropic in ferrous alloys.
Enargite – It is a copper arsenic sulphide mineral which poses substantial challenges in base metals production because of its high toxicity and the lack of developed commercial methods for its selective flotation from copper sulphides.
eNBs – These are also called evolved Node B. These refer to the base stations in a wire-less communication network which manage radio resource management (RRM) for user equipment (UE) and relay nodes (RNs), ensuring quality of service (QoS) and fairness while addressing interference and resource constraints. HeNB, or home eNB, is a subtype of eNB which at operates under similar principles but typically serves a limited area and can have additional constraints because of its backhaul link to the core network.
Encapsulation – The encasement of radioactive waste (normally low level and intermediate level wastes) by an encapsulent such as concrete.
Encapsulated healing agent – It is a liquid substance contained in microcapsules which, when released because of crack formation in a material, polymerizes and bonds the crack closed upon contact with an embedded catalyst.
Encased column – It is normally referred to as a concrete encased steel (CES) column. It is a heavy-duty structural member where a central steel section (such as an I-beam) is fully surrounded by, or ‘encased’ in, reinforced concrete. It functions as a composite column to maximize load-bearing capacity and improve fire and corrosion resistance.
Encasement – It is the process of enclosing a component (such as a pipe, structural beam, or soil mass) within a protective barrier. Its main purpose is to shield the material from environmental degradation, physical damage, and extreme temperatures.
Enclosed die forging – It is also known as impression die forging. It is a metal forming process where a preheated metal billet is forced into a set of dies which fully enclose the work-piece. These dies have cavities shaped to create the desired final part, ensuring a highly accurate and detailed product with minimal subsequent machining.
Enclosed industrial control panels – An enclosed industrial control panel is comprised of the enclosure, all components located within the enclosure, and all components mounted to the walls of the enclosure. The construction of the entire unit has been inspected, including its ability to safely function within the specified marked voltage, current, and short circuit current ratings (SCCRs).
Enclosed rotor – It refers to a rotating component (such as an electric motor rotor, or turbine disc) which operates within a protective casing, shroud, or stator. It isolates the mechanism from the external environment, shields the blades from foreign object damage (FOD), and improves both aerodynamic efficiency and noise reduction.
Enclosing envelope – It is also caked building envelop or enclosure. It is the physical separation between the interior conditioned environment of a building and the exterior, unconditioned environment. It serves as the ‘skin’ or shell which protects the structure’s interior, occupants, and contents from external elements like rain, snow, wind, sun, and temperature extremes. Enclosing envelope consists of all elements which form this boundary.
Enclosure – It is a specialized protective housing or chassis designed to contain, support, and shield electrical, electronic, or mechanical components from environmental hazards (dust, moisture, heat) and physical damage. It serves as an important interface, ensuring reliability by separating sensitive machinery from harsh surroundings.
Enclosure boundary – It defines the physical or theoretical limits (walls, panels, or fluid interfaces) which separate an internal system from its external environment. It dictates how heat, pressure, and acoustic or electro-magnetic waves interact with the space.
Enclosure protection – It is the design and application of specialized housings which shield sensitive electrical, electronic, or mechanical components from environmental hazards (dust, moisture), physical damage, and unauthorized access, while also protecting personnel from dangerous live parts. It ensures system reliability and safety using rated standards.
Enclosure volume – It is the total internal 3-dimensional space contained within a structure or boundary. It dictates ventilation efficiency, acoustic resonance, and thermal performance. It is formally calculated using the formula ‘volume = length x width x height’.
Encode direction – It determines the physical axis, path, or sequence used to convert mechanical motion, data, or signals into a standardized coded format.
Encoded message – It is information converted from its original, readable format into a new, specific format (code, symbol, or cipher) for secure transmission, efficient storage, or system compatibility. It ensures data remains safe from unauthorized access or is transformed into a standardized form for easier processing by computers.
Encoded signal – It refers to data or information which has been systematically converted into a specific electrical, optical, or digital format designed for efficient transmission, secure storage, or error correction. This process maps bits, characters, or symbols to physical characteristics like voltage levels, frequencies, or light pulses. It encompasses several key engineering applications.
Encoded state – It refers to the assignment of unique, specific binary patterns to each distinct mode or condition of a system, particularly in finite state machines (FSMs). It translates abstract system behaviours into physical signals (1s and 0s) to dictate hardware operations, logic gate requirements, and overall circuit efficiency.
Encoded version – It refers to data or information which has been systematically converted into an alternative, standardized format using specific algorithms, coding schemes, or compression techniques. It is mainly designed to enable efficient storage, secure transmission, or processing by machines.
Encoder side – It refers to the intentional design and optimization of the initial processing phase in an encoder-decoder architecture. It defines how raw inputs are processed, compressed, or measured before being transmitted or transformed.
Encoder signal – It refers to the electrical or optical output generated by a sensor which translates physical motion, such as rotation or linear displacement, into digital or analog data. Controllers and programmable logic controllers (PLCs) use these signals to track precise parameters like position, velocity, and direction of travel.
Encoding circuit – It is a combinational logic device which converts multiple input signals into a smaller, compressed binary code. It performs the inverse function of a decoder by translating an active, human-readable, or parallel input into a unique ‘n’-bit digital output representation.
Encoding complexity – It measures the computational resources (time, space, or hardware) and algorithm severity needed to translate source data into a specific format. It balances the trade-off between how efficiently data is compressed or transmitted and the processing burden placed on the system.
Encoding functions – These functions transform raw information or source data into a specific format, such as bits or physical signals, for transmission, storage, or processing. They are the critical mathematical and logical mappings ‘E(x)’ which convert original data ‘x’ into a codeword ‘c’, making it compatible with hardware or networks.
Encoding matrix – It is a mathematical matrix used to transform plaintext, signals, or data into a coded, secure, or transmissible format through matrix multiplication. It acts as a set of mathematical rules to map original information to a new representation, mainly used for encryption and error-correction.
Encoding method – It refers to the systematic process of designing, selecting, and implementing mathematical transformations which convert raw data into a structured, machine-readable format. It is a foundational pipeline in machine learning and data science, directly shaping a model’s efficiency, geometry, and predictive accuracy. The methodology dictates how categorical semantics (e.g., colours, zip codes, or text sequences) are mapped into mathematical structures. Choosing the correct technique dictates how well a system learns patterns while avoiding computational bottlenecks.
Encoding scheme – It is a standardized set of rules and algorithms used to convert data (such as text, numbers, or multimedia) into a specific, uniform format for secure storage, efficient transmission, or system compatibility. It acts as a universal dictionary that computers and hardware use to correctly translate, compress, and interpret information.
Encounter frequency – It is the measure of how many times two nodes come into contact with each other in a network, which is used to predict suitable next hops for message forwarding in encounter-based routing techniques. Encounter frequency is also the rate at which a moving system, experiences external, cyclical fluctuations. It measures how frequently these repetitive interactions happen relative to the moving vehicle’s frame of reference.
End – It is a strand of roving consisting of a given number of filaments gathered together. The group of filaments is considered an ‘end’ or strand before twisting, a ‘yarn’ after twist has been applied. It is an individual warp yarn, thread, fiber, or roving.
End approach – End approach describes the minimum horizontal distance, parallel to the runway, between the outermost extremities of the crane and the centre line of the hook.
End arch, wedge – It is a brick in which the large faces are inclined towards each other in a such a way that one of the end faces is narrower than the other.
End bearing – In steel and concrete construction, this refers to the physical support location where a beam or truss rests on a column, wall, or bearing plate.
End-bearing pile – It is a deep foundation structural element which passes through soft, compressible soil to transfer a building’s weight directly into a stiff, immovable layer of bedrock or dense gravel.
End bevel – It means weld end preparations for butt-welding.
End-centered – It consists of having an atom or group of atoms separated by a translation of the type 1/2, 1/2, 0 from a similar atom or group of atoms. The number of atoms in an end-centered cell is needed to be a multiple of 2.
End breakage rate – It is a metric which quantifies the frequency at which material breaks during a continuous production process. In industries like textile manufacturing, it measures the number of yarn or fibre strand breaks per specified unit of operational time, such as breaks per 1,000 spindle hours.
End connection – It is the type of connection supplied at the ends of a valve which allows its installation on a pipeline. Weld end (WE), raised face flange (RF), ring-type joint (RTJ) are the most common end types.
End constraint – It is a reaction at structures such as a rigid flange, anchor, or a rigid tie-in. The restraint prevents pipe expansion. The restraining force generated is calculated by summing the internal pressure and thermal expansion forces. Soil friction is not a factor in this case as there is no longitudinal movement.
End count – It is an exact number of ends supplied on a ball of roving.
End defects – These defects normally refer to irregularities, discontinuities, or physical imperfections located at the, or associated with, the end of a metal product, frequently occurring during casting, rolling, or extrusion processes. Casting end defects are pipe which is an inverted-cone shaped cavity which forms at the top (end) of an ingot during solidification because of the shrinkage. Rolling end defects are irregularities on the trailing or leading ends of rolled stock, such as split ends (alligatoring), caused by inconsistent deformation during hot rolling or cold rolling. Extrusion end defects are also known as the extrusion defect or funnel. This defect is where the oxidized surface of the billet flows toward the centre of the extruded bar, resulting in a pipe-like inclusion. Welding end defects are the defects which occur at the end of a weld pass, such as crater cracks or improper termination of the weld.
End delivery – It is frequently referred to as end-to-end delivery. It is the process of guiding a system or product from its initial conceptual design, through manufacturing and testing, all the way to final deployment, operation, and customer handover. The concept spans the full operational lifecycle, ensuring that the final output meets all requirements and functions seamlessly in the real world.
End dimension – It is also called end-to-end dimension. It defines the total physical length of a component, such as a valve or pipe fitting, measured from one extremity to the other. It ensures installation and replacement interchangeability.
End-drive conveyor system – It is a conveyor configuration with the drive unit situated at one end, needing periodic checks to uphold proper alignment and ensure the system’s efficient operation.
Ended pin – It is frequently called a ‘pin-ended’ support or connection) refers to a joint which allows a beam or column to rotate freely while entirely preventing it from moving (translating) in any direction. This is a fundamental concept in structural engineering and mechanics.
End effect – It refers to the inaccurate or anomalous behaviour which occurs at the boundaries or edges of a dataset, system, or physical object, departing from the behaviour observed in the middle. These effects are normal in signal processing, modelling, and physical measurements where boundary conditions differ from the interior.
End effector – It is a peripheral device attached to the wrist of a robotic arm, designed to interact with the environment to perform a specific task. Frequently called the ‘business end of the robot’, it enables the machine to execute operations like gripping, welding, painting, or sensing.
End-effector position – It refers to the specific spatial coordinates and orientation of a robotic manipulator’s ‘hand’ or tool. It defines where the physical device, such as a gripper, welding torch, or sensor, is located within the work-space relative to a fixed, base coordinate system.
End elevation – It is a 2D orthographic projection which shows the side view of an object, building, or structure. It shows the height, width, and cross-profile as seen from a perpendicular angle relative to the front or main view.
End face – In a standard square brick, it is one of the faces which is bounded by the two shortest dimensions.
End face defects – These are structural, geometrical, or surface imperfections located on the flat, terminal surfaces (ends) of metal products, such as steel coils, billets, pipes, or machined parts. These defects are normally caused by manufacturing processes like rolling, forging, casting, or cutting, and can lead to premature structural failure, poor sealing, or failure to meet dimensional tolerances.
End feather, feather end – It is a brick, in which one of the faces is inclined from the top of one end face to the bottom of the opposite one, where the thickness is reduced normally to zero.
End feed – It refers to a casting technique or a specific feeding mechanism where molten metal is introduced, or a riser is placed, at the end or edge of a casting cavity to supply hot metal during solidification.
End-feeding attachments – These are frequently associated with riser or feeder design. These refer to specific, localized feeding methods or added components designed to provide molten metal to the last part of a casting to solidify. In piping systems, end-feeding attachments (like flanges or welded ends) connect pipes to other equipment, valves, or fixtures. They allow for the secure fastening, welding, or sealing of a pipe end to a component within a system.
End-feeding heads – These are frequently called end risers or simply risers. These are reservoirs of molten metal designed to counteract shrinkage as a casting solidifies. They are placed at the extremities (ends) of a casting or connected to the last part to freeze, ensuring that the casting remains sound and free from cavities or porosity.
End grain – It is the grain flow lines which intersect with the exposed surface of the ends of bar stock, tubing, or the parting lines of forgings. A long, narrow test sample sectioned so that the grain is parallel to the longitudinal axis of the sample has no exposed end grain, except at the extreme ends. In contrast, a corresponding sample cut in the transverse direction has end-grain exposure at all points along its length. End grain is especially pronounced in the short-transverse direction on die forgings designed with a flash line.
End-grain attack – It is the preferential corrosive attack of grains exposed by cutting through the cross section or at the parting lines of forgings.
End-grain exposure – It refers to the exposure of the cross-sectional, transverse surface of a metal component, where the elongated grains (micro-structure) resulting from manufacturing processes like hot rolling or forging are perpendicular to the surface. This orientation exposes the edges of the grain boundaries, which are frequently enriched with inclusions (like sulphides or phosphorus), making that specific area highly susceptible to chemical attack, localized pitting, and intergranular corrosion.
End hooks – These are pronounced bends which appear close (normally within 455 milli-meters) to the leading or trailing ends of some tubular products.
Ending scheme – It refers to the closing phase of system design where conceptual models and abstract parameters are translated into finalized, actionable specifications. This step finalizes design boundaries, material tolerances, and operational parameters before entering the prototyping or manufacturing phase.
Endless length – It is the length of a closed belt (without splice allowances).
Endless loop – It is also called an infinite loop. It is a sequence of instructions in computer programming which repeats indefinitely. It occurs when a loop’s exit condition is missing, poorly defined, or impossible to meet, causing the programme to run forever until forcibly terminated by an external force.
Endless rolling technology – It is a process method for the rolling of the bars and rods (also known as long products) from the billets. It consists of a welding arrangement designed to endlessly join billets together in order to provide a continuous supply of material to the rolling mill train. It is enabled by welding of the billets which come from a reheating furnace at the upstream side of the stands of rolling mill train. In fact, the joining of the tail end of the billet being rolled and the head end of the billet to be rolled is one of the key aspects of the endless rolling technology.
Endless splice – It is the technique which is used to connect the terminals of a conveyor belt, creating an unbroken loop without relying on mechanical fasteners. This process requires expert installation and regular inspections.
End-loaded split (ELS) test – It is a standardized fracture mechanics procedure used to measure mode-II (in-plane shear) interlaminar fracture toughness of composite materials and structural adhesives. It is a standardized fracture mechanics method. It involves bending a pre-cracked sample clamped at one end while applying a load at the opposite end to induce stable crack growth.
End mark – It is a roll mark caused by the end of a sheet marking the roll during hot rolling or cold rolling.
End-members – These refer to the pure spectral signatures or components which make up the pixel spectra in hyperspectral imagery, which are necessary for accurate unmixing analysis. They can be specified through different methods such as laboratory reflectance spectra, spectral libraries, automated techniques, and variable bundles which account for spectral variability. End-members are also the pure, distinct chemical components or phases which define the boundaries of a phase diagram or solid solution series. They represent the 100 % pure versions of the materials being mixed, alloyed, or analyzed, providing a baseline reference for compositions.
End mill – It is a specialized cylindrical cutting tool used in industrial milling applications to remove material from a work-piece. Unlike standard drill bits, which only cut axially (downward), end mills feature cutting edges on both their sides and bottom, allowing for both axial plunge-cutting and radial-profiling.
End milling – It is a method of machining with a rotating cutting tool with cutting edges on both the face end and the periphery. It is a subtractive machining process where a rotating, multi-tooth cutting tool (an end mill) removes material from a work-piece. Distinguished by cutting edges on both its outer periphery and bottom, it can cut laterally and plunge axially to create complex 3-D shapes, slots, and contours.
End-notched flexure – It is an experimental testing configuration used to measure the inter-laminar fracture toughness of bonded joints and composite laminates. It subjects a pre-cracked beam to three-point bending to determine the material’s resistance to mode-II (sliding or shear) fracture.
End notched flexure (ENF) test – It is a standard mechanical test used to measure mode-II (in-plane shear) interlaminar fracture toughness of composite laminates and bonded joints. It determines a material’s resistance to crack propagation or delamination under shear forces.
Endochronic theory – It is a theory of plasticity which does not need a yield surface for the transition from elastic to elasto-plastic behaviour, allowing for the prediction of different mechanical phenomena in materials such as concrete, rock, and powders.
End-of-life – It refers to the final stage in a product’s lifecycle where the manufacturer ceases production, sales, and active support (updates, patches, or repairs) for hardware or software. It signals that a product is obsolete, needing users to plan for upgrades, replacements, or continued use at their own risk.
End-of-life vehicle – It is a motor vehicle which has reached the end of its useful service life and is classified as waste. This classification is triggered by age, severe damage (total loss), failed fitness testing, registration cancellation, or a voluntary declaration of being non-roadworthy by the owner.
End-of-life (EoL) waste management – it is the final phase of a product’s life cycle, frequently called the ‘grave’, comprising the collection, treatment, and disposal or recovery of products no longer useful to the consumer. It focuses on minimizing environmental impact through recycling, reuse, repair, or safe disposal rather than simple discarding.
End-of-pipe limit – It is also known as case-specific technology limit, or sector-specific technology limit. End-of-pipe limits are either technology or water quality based. If they are water quality based, then the limits are calculated to support a waste-load allocation value, the value needed to maintain in-stream guidelines. A technology limit is formulated on some statistical derivation of existing performance, or published sector-specific limits. The average monthly limit (AML) and the maximum daily limit (MDL) are end-of-pipe limits which are calculated either to ensure that the waste-load allocation is not exceeded at some specified frequency, or they are based on technological capability (i.e., the limits are either sector-specific or case-specific technology based).
End-of-pipe protection – It refers to added technical installations for environmental control of emissions. They operate independently from the production process or are an identifiable part added on to production facilities.
End of pipe techniques – These are methods which are used to remove already formed contaminants from a stream of air, water, waste, product or similar. These techniques are called ‘end-of-pipe’ as they are normally implemented as a last stage of a process before the stream is disposed of or delivered.
Endogenic ore deposits – Endogenic ore deposits are normally intimately associated with geological structures. Ore deposits are grouped as endogenetic when their origin is associated with thermal processes and when, in general, they are clearly related to magmatic and tectonic events.
Endogenous factor – It is an internal element or variable whose value is determined by the relationships and interactions within a specific model or system. These are the outputs and dependent variables which change in response to external inputs or design choices.
Endogenous inclusions – These are inclusions which originate from the steelmaking process.
Endogenous variable – It is a factor within a system or model whose value is determined by its relationships with other variables inside that same system. It serves as a dependent output or internal state which reacts to external inputs (exogenous variables) and system parameters.
Endohedral doping – It is an advanced nano-scale engineering technique where dopant atoms or molecules are encapsulated inside the hollow interior of a molecular cage or tube (like fullerenes or carbon nano-tubes), rather than being substituted into its atomic lattice or sitting on its outer surface.
Endorsement – It is the act of partners within a partnership formally expressing their assent, publicly and definitively, to proceed with a policy, plan, or initiative.
Endothermal heat of solution – It is the net absorption of heat which occurs when a solute dissolves in a solvent, resulting in a positive enthalpy change ‘dHsoln = above 0’. This process feels cold to the touch since the energy needed to break apart solute and solvent bonds exceeds the energy released during solvation.
Endothermic atmosphere – It is a gas mixture produced by the partial combustion of a hydrocarbon gas with air in an endothermic reaction. It is also known as endogas.
Endothermic atmosphere (gas) – It is a reducing gas atmosphere used in sintering and produced by the reaction of a hydrocarbon fuel gas and air over a catalyst with the aid of an external heat source. It is low in carbon dioxide and water vapour with relatively large percentages of hydrogen and carbon mono-oxide. Maximum combustibles are around 60 %.
Endothermic furnace atmosphere – It is a controlled, protective gas mixture produced by reacting hydrocarbon fuel (natural gas or propane) with air over a heated catalyst. It is used in heat treatment to provide a reducing environment, preventing oxidation and surface decarburization during processes like hardening, carburizing, and sintering.
Endothermic heat absorption – It is the absorption of heat energy from its surroundings, resulting in a temperature decrease of the immediate environment. This process is characterized by a positive enthalpy change (delta H is above zero), meaning the system gains thermal energy to break bonds or change states.
Endothermic nitrogen-base atmosphere – It is a type of controlled, reducing gas mixture used in industrial heat treating which needs an external heat source to form. It is produced by passing a lean mixture of air and hydrocarbon gas (such as methane or propane) over a heated catalyst, breaking the compounds down to create a protective atmosphere which is roughly 40 % hydrogen (H2), 40 % nitrogen (N2), and 20 % carbon mono-oxide (CO). This atmosphere is normally considered the ‘work-horse’ of heat treatment for hardening steel without changing its surface chemistry.
Endothermic nitrogen / methanol atmosphere – It is a synthetic, reducing furnace atmosphere used in heat treating (e.g., carburizing, hardening) produced by injecting methanol (CH3OH) and nitrogen (N2) directly into a hot furnace. The methanol thermally dissociates into hydrogen and carbon mono-oxide, mimicking traditional endothermic generator gas (around 40 % hydrogen (H2), 20 % carbon mono-oxide (CO), 40 % nitrogen (N2) but with higher purity, lower dew points, and improved consistency.
Endothermic peak – It is a distinct downward deflection on a thermal analysis graph (like a differential scanning calorimetry (DSC) curve). It indicates that a material is absorbing heat from its surroundings to undergo a specific physical or chemical change. Endothermic peaks typically represent several events such as melting, vapourization or evaporation, decomposition, and (iv) crystal transitions.
Endothermic process – It a chemical or physical process which absorbs heat from its surroundings. In terms of thermodynamics, it is a thermodynamic process with an increase in the enthalpy (or internal energy) of the system. In an endothermic process, the heat that a system absorbs is thermal energy transfer into the system. Hence, an endothermic process normally leads to an increase in the temperature of the system and a decrease in that of the surroundings.
Endothermic reaction – It is the designating or pertaining to a reaction which involves the absorption of heat. It is a process which absorbs thermal energy from its surroundings to proceed, resulting in a positive enthalpy change (dH is above 0). These reactions need a continuous external energy input to maintain equilibrium, optimize conversion rates, and drive the reaction forward.
End-plate – It is a widely used connecting element in bolted connections, typically shop welded to the end of a steel beam, facilitating the connection to hollow columns with bolts, and available in extended or flush types for varying strength and ductility needs.
End-plate connection – It is a structural joint used in steel construction where a flat steel plate is welded to the end of a beam. This plate is then bolted to a supporting column or another beam. It is a highly efficient, cost-effective way to transfer shear or moment forces between members.
End point – It refers to a specific, defined termination point within a process or system, typically marking the end of a process, a physical location in a network. In metallurgy, the end point refers to the precise moment a metallurgical process, such as steelmaking, refining, or smelting, is complete and is to be stopped to achieve the desired material composition and quality. It represents the completion of specific chemical reactions, such as the oxidation of impurities, at which point the furnace or reactor is tapped. In titration, it is the physical moment when an indicator changes colour or physical property change, signaling that the titration is complete and the reaction is finished. It signals the user to stop adding the titrant and occurs just after the stoichiometric equivalence point.
End-point carbon prediction – In basic oxygen furnace (BOF) steelmaking, it refers to predicting the final carbon content in the molten steel bath before it is tapped from the furnace. This prediction is crucial for achieving the desired steel composition, optimizing production efficiency, and minimizing energy consumption. Accurate endpoint prediction helps ensure the steel is ready for the next stage of production.
End-point drum – It is the pulley positioned at the discharge or delivery end of a conveyor, which undergoes periodic inspections to evaluate wear, and balance, and ensure proper alignment.
End product quality – It defines the exact degree to which a finished product meets or exceeds customer needs and adheres to technical specifications. It is measured by evaluating reliability, functionality, durability, and safety through controlled manufacturing and design processes.
End pulley – It is the pulley at the discharge or delivery end of the conveyor, necessitates regular inspections for wear, balance, and alignment.
End-quench hardenability test – It is a laboratory procedure for determining the hardenability of a steel or other ferrous alloy. It is widely referred to as the Jominy test. Hardenability is determined by heating a standard sample above the upper critical temperature, placing the hot sample in a fixture so that a stream of cold water impinges on one end, and, after cooling to room temperature is completed, measuring the hardness near the surface of the specimen at regularly spaced intervals along its length. The data are normally plotted as hardness against distance from the quenched end.
End return – It is the continuation of a fillet weld around a corner of a member as an extension of the principal weld.
End seal – It is a device which prevents the leakage of fluids along rotating shafts. Sealing is accomplished by a stationary primary-seal ring bearing against the face of a mating ring mounted on a shaft. Axial pressure maintains the contact between seal ring and mating ring.
End skew – It is a brick in which one face makes an angle of 60-degree with one of the side faces and 120-degree with the other which of reduced length.
End shear – It refers to the maximum internal shear force experienced at the extreme ends of a structural member (like a beam) where it connects to a support (such as a column or wall). It represents the exact reaction force needed to keep the structure in static equilibrium.
End shortening – It is the reduction in physical length of a structural member (like a column or stiffener) caused by an applied compressive load. It represents the combined effect of axial strain and buckling. Engineers use load-end shortening curves to model and evaluate a material’s pre-collapse and post-collapse behaviour.
End slope – It typically refers to the inclined surface at the termination of a structure or earthwork.
End state – It is the state and condition to which the site of a designated nuclear power station or facility is required to be restored at the time of decommissioning for the unrestricted use of a site.
End structure – It refers to the supporting framework or specialized components at the physical extremity of a vehicle, pipeline, or electrical line.
End-to-end (E2E) management – It is the oversight of a complete operational work-flow from its initial trigger to final delivery. Instead of breaking a work-flow into departmental silos, it ensures smooth transitions across every participant, system, and process, aiming to optimize resources and deliver a unified final result.
End-to-end (E2E) principle – It is a design principle in computer networking which needs application-specific features (such as reliability and security) to be implemented in the communicating end nodes of the network, instead of in the network itself. Intermediary nodes (such as gateways and routers) which exist to establish the network can still implement these features to improve efficiency but do not guarantee end-to-end functionality.
End-to-end vector – It mainly refers to a term in polymer physics and physical chemistry. It is the spatial displacement vector ‘R’ which points directly from the starting monomer (or atom) of a molecular chain to the terminal monomer (or atom).
End treatment – it refers to the specialized finishing process preparing a pipe’s ends for field welding and coating. It involves cutting, milling, brushing, or peeling. End treatment is also a structural feature designed to protect exposed, hazardous edges of barriers (like guard-rails) or drainage pipes (like culverts). Its main purpose is to safely absorb the impact of a crashing vehicle or prevent hydraulic erosion and scouring at structural openings.
End trucks – They are located on either side of the crane bridge. They house the wheels on which the entire crane travels. It is an assembly consisting of structural members, wheels, bearings, and axles etc., which supports the bridge girder(s) or the trolley cross member(s).
Endurance – It is the capacity of a material to withstand repeated application of stress.
Endurance limit – It is an obsolete term which is used to describe a characteristic in components subject to fatigue cracking. It does not reflect the current understanding of how fatigue cracks initiate and grow. It referred to the maximum stress below which a material can presumably endure an infinite number of stress cycles. If the stress is not completely reversed, the value of the mean stress, the minimum stress, or the stress ratio also should be stated.
Endurance ratio – It is the ratio of the endurance limit for completely reversed flexural stress to the tensile strength of a given material.
Endurance test – It is a method used to evaluate a product, component, or system’s ability to withstand prolonged, cyclic, or repetitive stress over an extended operational lifespan. The goal is to uncover long-term wear, fatigue, or performance degradation without immediately destroying the sample.
End user – It is the person or persons who eventually uses the product. Products are designed with end users in mind.
End user license agreement – It is a legally binding contract between a technology / process developer / vendor and the end-user, granting a restricted license to use the technology / process while retaining ownership. It defines permitted use, restricts modification and reverse engineering, disclaims warranties, and limits liability to protect intellectual property.
End voltage – In power transmission and distribution, electrical lines have a sending-end voltage (where power originates) and a receiving-end voltage (the end voltage where the load or consumer receives power). Because of wire resistance and load variations, the receiving end voltage is usually lower than the sending end voltage.
End-wall burners – These are specialized combustion devices located on the end walls (rather than side walls) of a furnace, typically a reverberatory furnace or a flash smelting furnace, which direct flames horizontally over the molten bath to provide heat for melting or refining operations. These burners are critical in metallurgical processes such as copper smelting, anode furnaces, and ladle preheating, helping to maintain high temperatures required to prevent molten metal from solidifying.
Energain – It is a commercial phase change material (PCM) which consists of a flexible sheet 5 millimeters thick, made up of 60 % micro-encapsulated paraffin wax, laminated on both sides with aluminum.
Energetic – It refers to chemical substances or mixtures which possess a large capacity for storing chemical energy, which can be rapidly released through reactions triggered by external stimuli such as mechanical or thermal shock waves.
Energetic ion – It is an atom or molecule which has lost or gained electrons (giving it a net electrical charge) and possesses an unusually high kinetic energy, typically ranging from a few electron volts (eV) to mega electron volts (MeV).
Energiron – It is a highly efficient, environmentally clean direct reduction (DR) technology used in the steel industry to convert iron ore into metallic iron. It utilizes a highly flexible shaft furnace system capable of using different reducing gases, including pure hydrogen, to minimize carbon emissions.
Energiron direct reduction technology – It is a gas based direct reduction technology. Energiron process converts iron ore pellets or lumps into metallic iron. It uses the HYL direct reduction technology developed jointly by Tenova and Danieli and is a competitive and environmentally clean solution for lowering the liquid steel production cost. It uses a simple plant configuration, has flexibility for using different sources of reducing gases and has a very efficient and flexible use of iron ores. Energiron process uses a shaft reduction furnace to produce direct reduced iron. The main characteristics of the Energiron process consists of (i) utilization of hydrogen rich reducing gases with hydrogen to carbon mono-oxide ratio of more than 4, (ii) high reduction temperature normally more than 930 deg C, and (iii) high operating pressure normally in the range of 0.5 MPa to 0.8 MPa. The higher operating pressure has several characteristics which include (i) lower gas velocity, (ii) lower dragging force, (iii) lesser dust carry over, (iv) lower consumption of iron bearing materials, (v) higher ratio of plant capacity/size, and (vi) lower power consumption due to lower compression factor. High operating pressure in the shaft furnace also results into a high furnace productivity which is around 9 tons per hour per square meter area.
Energization – It is the act of providing energy to a system or the state of being filled with active vigour. In electrical engineering, it is the process of applying an electrical voltage, connecting a circuit, or closing a switch so that electrical current can safely flow through a system or component. In management process, it is the act of invigorating, motivating, or rousing people into an active, enthusiastic state.
Energizing coil – It is a wire winding which generates a magnetic field when an electric current passes through it. This electro-magnetism is used to actuate mechanical switches (like in relays and contactors) or induce secondary electric currents in transformers and sensors.
Energy – It is the quantitative property which is transferred to a body or to a physical system, recognizable in the performance of work and in the form of heat and light. Energy is a conserved quantity. The law of conservation of energy states that energy can be converted in form, but not created or destroyed. Matter and energy may also be converted to one another. The unit of measurement for energy in the International System of Units (SI) is the joule (J). Forms of energy include the kinetic energy of a moving object, the potential energy stored by an object (for instance due to its position in a field), the elastic energy stored in a solid object, chemical energy associated with chemical reactions, the radiant energy carried by electromagnetic radiation, the internal energy contained within a thermo-dynamic system, and rest energy associated with an object’s rest mass.
Energy absorption – It refers to the process of dissipating the input energy from external loading (e.g., because of impact / collision in particular) by plastic deformation (e.g., for metals and polymers) or fracture (e.g., for ceramics and composites). The energy-absorption behaviour of materials and structures plays a key role in the safety of structures under impact.
Energy absorption capability – It is the maximum quantity of kinetic or mechanical energy a material, component, or structure can dissipate or absorb, frequently through controlled deformation (like crushing or bending) or fracturing, before structural failure.
Energy absorption capacity – It is the ability of a material or structure to dissipate or store energy from external loads (typically impacts or collisions) through deformation, fracture, or damage mechanisms. It is a critical performance indicator, frequently measured as the area under a force-displacement or stress-strain curve.
Energy absorption mechanism – It is the physical or chemical process by which a system dissipates external energy, such as kinetic force from an impact or electro-magnetic radiation, converting it into other forms like heat, sound, or structural deformation.
Energy amplifier – It is a proposed type of sub-critical nuclear power reactor which uses a particle accelerator to stimulate a reaction. Instead of a traditional self-sustaining chain reaction, the particle beam triggers a cascade of reactions which release enough energy to power the accelerator while generating excess electricity.
Energy analysis technique – It is a systematic method used to evaluate how energy is consumed, converted, and lost within a system. It involves tracking energy inputs and outputs to optimize efficiency, reduce operational costs, and identify areas for conservation.
Energy application – It refers to the practical use, consumption, conversion, or storage of energy to perform a specific task. This concept spans daily human usage (like powering homes), industrial operations, and engineering technologies (such as renewable power generation and battery storage).
Energy auction – It is a competitive bidding process used by governments or grid operators to procure electricity or allocate energy generation capacity. The main goal is to balance grid supply and demand while securing long-term contracts at the lowest possible cost.
Energy audit – Energy audit is the inspection, examination, analysis and evaluation of the physical and financial processes of an industrial plant relating to the use of the energy. The aim of the energy audit is to systematically identify the potential for saving energy and make recommendations for improvement. It is a key requirement for an industrial plant. It helps the plant management to identify and realize energy efficiency improvements in a systematic way. It assists the plant management in understanding how it uses energy and helps to identify the areas where waste occurs and where opportunities for improvement exist.
Energy balance – It refers to a comprehensive accounting of energy inputs, outputs, and transformations within a specific industrial process or system. It essentially tracks the flow of energy from its initial source to its final use, including any energy losses or transformations along the way.
Energy balance calculation – It applies the law of conservation of energy to quantify the flow, transformation, and accumulation of energy within a specific system. Depending on the context, it is used in engineering to design industrial processes, or in economics to track energy supply and demand.
Energy balance equation – It is the mathematical expression of the ‘first law of thermodynamics’, stating that energy cannot be created or destroyed, only transferred or transformed. It dictates that the total energy entering a system is to equal the total energy leaving the system, plus any accumulation of energy within that system. The fundamental engineering equation is written as ‘energy-in – energy-out = energy accumulated’.
Energy band – It is a range of energy levels which electrons can occupy in a solid, which influences the material’s electrical properties based on how these levels are filled, leading to classifications such as conductors, semiconductors, and insulators.
Energy band diagram – It is a graphical tool used in solid-state physics and electrical engineering to visualize how electron energy levels change across the spatial dimension of a material or device. It explains the electrical and optical properties of semiconductors, such as why and how current flows.
Energy band gap – It is the forbidden energy range between the top of the valence band (highest filled electron band) and the bottom of the conduction band (lowest unfilled band) in a solid. It is the minimum energy needed to excite an electron from a bound state to a mobile state, allowing electrical conduction.
Energy band theory – It explains how isolated atomic energy levels overlap to form continuous ‘bands’ of energy in solids. It is the foundation for understanding electrical, optical, and thermal properties in engineering, classifying materials as conductors, insulators, or semi-conductors based on their specific energy band structure.
Energy band-width – It refers to the potential for energy-efficiency improvements within different sectors, assessed through classifications such as ‘current technology’, ‘state of the art’, ‘practical minimum’, and ‘thermodynamic minimum’, which provide benchmarks for estimating energy demand and savings.
Energy barrier – It is the minimum energy threshold a system is required to overcome to undergo a physical or chemical transformation. It represents an energy ‘hurdle’ which dictates process rates, stability, and whether a reaction or transition occurs spontaneously.
Energy based detection – It refers to a method of sensing signals by analyzing the energy levels of received signals, utilizing techniques such as fast fourier transform (FFT) based spectral estimates to filter out noise and detect both narrow-band and wide-band signals effectively. This approach aims to optimize sensitivity while managing the trade-offs between band-width resolution and sensing time.
Energy-based parameter – It is a metric which evaluates system performance, material durability, or structural response based on cumulative energy, such as work done, kinetic energy, or energy dissipated. These parameters are used to predict life-spans, evaluate seismic damage, and model physical dependencies.
Energy basis – It broadly defines the specific standard or metric against which energy data is measured, calculated, or priced.
Energy beam – It is a directed, focused stream of particles or electro-magnetic waves (such as lasers or X-rays) used to transfer focused energy over a distance. It is broadly defined across several scientific, industrial, and pop-culture fields, each utilizing the concept for specific applications.
Energy behaviour – It encompasses all human actions, habits, and mental processes which influence how energy is consumed, managed, or produced. It includes daily actions (usage), long-term purchases (investments), and equipment maintenance that directly impact the organization’s overall carbon footprint and utility costs.
Energy benefit – It typically refers to the positive impacts derived from energy efficiency or the advantages of consuming specific power sources. It spans everything from immediate cost savings to broader environmental and social improvements.
Energy capacity – It is the total quantity of energy a system can store, produce, or deliver over time. It dictates ‘how long’ a system can operate rather than how fast it produces energy. Depending on the context, it is typically measured in watt-hours, kilo-watt-hours, or mega-watt-hours.
Energy carrier – It is a substance or system which stores energy and can be transported to produce mechanical work, heat, or operate chemical and physical processes elsewhere. Unlike main energy sources found in nature, they act as an intermediary, transforming energy into a usable format for consumers.
Energy cascade – It refers to the process where kinetic energy is transferred from large-scale, main flow structures to progressively smaller vortices or eddies, until the energy is ultimately dissipated as heat by viscous forces.
Energy collection – It is also called energy harvesting. It is the process of capturing and converting ambient, naturally occurring, or waste energy from the environment into usable electrical or thermal power. Its main goal is to provide autonomous, battery-free power for small electronic circuits and sensors.
Energy commission – It refers to a statutory government regulatory body which sets policies, issues licenses, and enforces standards to ensure safe, efficient, and sustainable energy usage.
Energy commissioning – It is the systematic process of testing and verifying that a facility’s energy systems operate optimally and securely.
Energy communication – It mainly refers to the transmission of data and information to coordinate, monitor, and optimize power networks. Alternatively, in hardware and networking, it denotes the energy consumed to transfer data across systems.
Energy compaction – It is the process of redistributing pixel energy in an image to concentrate it into a small number of high-valued coefficients, hence improving the significance of these coefficients for further coding. This transformation does not result in data compression but facilitates a more efficient representation of the image.
Energy component – It has two main definitions depending on context. It refers to either a physical device which converts or manages energy (like a turbine, battery, or heat exchanger), or a quantifiable mathematical portion of total energy within a thermodynamic or mechanical system (such as kinetic, potential, or thermal energy).
Energy conservation – It plays a fundamental role in an industrial plant. This approach to the processes of the plant helps the plant management to focus on to control activities and practices for the reduction of the energy wastes. Energy conservation not only has a positive effect on the energy efficiency, but it also implies a reduced use of energy sources, possibly integrated with the recovery of the waste energy. The goals and objectives of energy conservation activities in a plant include (i) provision of the opportunities to decrease the specific energy consumption, (ii) provision of good practices to utilize energy sources more effectively, (iii) provision of good practices to recover waste energy (heat, gas) wherever practical, (iv) to enable the plant management to develop plans for plant energy intensity reduction, and (v) to use benchmarking technique for the prioritization of investments to maximize the energy conservation and adopt practices with the biggest impact.
Energy conservation in buildings – It is the systematic process of reducing structural energy consumption without compromising occupant thermal comfort or core functionality. It involves optimizing building design, envelope materials, and active systems to minimize reliance on non-renewable power while maintaining a healthy, productive indoor environment.
Energy conservation law – It states that energy cannot be created or destroyed. It can only be transformed or transferred from one form to another. In an isolated system, the total energy remains constant over time.
Energy conservation measures – These are specific technological resources, operational strategies, or projects implemented to reduce energy consumption. The core objective is to minimize energy waste and optimize resource usage without compromising productivity, safety, or occupant comfort. These measures are foundational to building performance, industrial processes, and sustainability.
Energy conservation through energy storage – It is a paradigm focused on capturing and holding energy produced at one time for use later. It minimizes main energy waste, balances supply-demand imbalances, and maximizes efficiency across thermal, electrical, and mechanical systems.
Energy constraint – It is a design limitation or operational boundary related to energy storage, consumption, or generation. It dictates the maximum energy a system can use, the rate at which it can use it, or the thresholds needed to prevent failure, excessive heat, and battery depletion.
Energy consumer – It is a physical system, device, facility, or entity which draws upon an energy source to perform work or operate. Broadly defined, these are end-users, such as industries, buildings, or equipments, which convert energy forms (e.g., electricity, gas, heat) into useful output, while frequently interacting with modern, bi-directional grids.
Energy consumption – It is the total quantity of energy used by a device, system, or process over a specific period of time. It is distinct from power, which is the rate at which energy is transferred.
Energy consumption data – It refers to the systematic measurement, collection, and analysis of the energy used by a system, device, or facility over time. It quantifies how much energy (e.g., electricity in kilo-watt hours, thermal energy in joules or kilo-calories) is needed to perform specific tasks, allowing engineers to benchmark efficiency and reduce operating costs.
Energy consumption reduction – It is the systematic process of minimizing the power needed to operate devices, systems, or industrial processes. It is achieved by improving energy efficiency (maintaining the same output with less input) and eliminating waste, hence optimizing performance, lowering operating costs, and reducing greenhouse gas emissions.
Energy conversion – It is the process of transforming energy from naturally occurring or raw sources into forms which can be utilized for human applications. It is governed by the ‘law of conservation of energy’, which dictates that energy cannot be created or destroyed, only changed from one form to another.
Energy conversion efficiency – It is the ratio of useful energy output to the total energy input, expressed as a percentage. It measures a device or system’s ability to transform energy from one form into another (e.g., thermal to mechanical) without losing it to waste heat, friction, or other irreversibilities.
Energy crisis – It is defined as a critical bottleneck where system load (demand) exceeds available generation, transmission, or distribution capacity (supply). It threatens grid stability or critical infrastructure, frequently resulting in systemic failures like rolling blackouts, forced load shedding, or extreme price volatility.
Energy defect – It typically refers to defect formation energy, the energy needed to create a crystallographic flaw (such as a vacancy or interstitial atom) within a host lattice. It determines material stability, doping ability, and ion transport.
Energy demand – It is the total quantity of power or thermal energy needed by consumers (e.g., buildings, industrial processes) to perform work or maintain comfortable conditions. It is categorized into peak demand (the highest momentary rate of energy used) and energy consumption (total energy used over time).
Energy demand analysis – It is the systematic evaluation of how and where energy is consumed within a system. It quantifies power requirements, identifies inefficiencies, and evaluates the impact of variables like climate and technology, enabling the design of optimized, cost-effective, and sustainable energy systems.
Energy demand management – It is frequently called ‘demand-side management’ (DSM) or ‘demand-side response’ (DSR), is the modification of consumer energy use. It uses automation, smart metering, and control strategies to optimize consumption, reduce peak loads, and align demand with available energy supplies.
Energy density – It is the quantity of usable energy stored within a system, material, or region of space per unit volume. It is used to evaluate the efficiency and physical footprint of power sources like batteries, capacitors, and fuels.
Energy density analysis – It is a method for partitioning the total energy of a system into respective atomic energy densities, which include contributions from nuclear-nuclear repulsion, kinetic energy, nuclear-electron attraction, classical Coulomb interactions, and exchange-correlation energy. Energy density analysis (EDA) provides insights into the electron density distribution and the nature of chemical bonds within a material.
Energy detection – It is a signal processing technique used to identify the presence of a signal by measuring its power within a specific bandwidth and comparing it to a pre-determined noise threshold. It is widely used in communications, radar, and cognitive radio for spectrum sensing and channel assessment.
Energy detector – It is a non-coherent system which senses the presence of a signal by measuring its power or energy level, without needing prior knowledge of the signal’s data or modulation type.
Energy development – It is the systematic process of researching, designing, and optimizing systems to explore, harness, and convert natural resources into usable power. It encompasses the entire lifecycle of power generation, from resource extraction and conversion to efficient distribution and sustainable consumption.
Energy-dispersive spectrometer – It is an analytical technique used to identify and quantify the elemental composition of a sample by detecting characteristic X-rays emitted when it is bombarded with an electron beam. Mainly paired with scanning electron microscopes (SEM), it provides rapid qualitative and quantitative analysis of elements from beryllium to californium.
Energy-dispersive spectroscopy – It is a method of X-ray analysis which discriminates by energy levels the characteristic x-rays emitted from the sample.
Energy dispersive X-ray analysis – It is also known as energy dispersive spectroscopy (EDS). It is an analytical method used to evaluate the elemental composition of materials by detecting X-rays emitted when high-energy electrons interact with a sample. Energy dispersive X-ray (EDX) systems are typically integrated with electron microscopy and are effective for mapping the spatial distribution of elements within materials.
Energy dispersive X-Ray spectrometer – It is an analytical tool integrated with electron micro-scopes (like scanning electron microscope or transmission electron microscope) used to determine a material’s elemental composition. It identifies elements by detecting and measuring the energy of characteristic X-rays emitted when an electron beam bombards the sample.
Energy-dispersive X-ray spectroscopy – It is an analytical technique used for the elemental analysis or chemical characterization of a sample. It relies on an interaction of some source of X-ray excitation and a sample. Its characterization capabilities are due in large part to the fundamental principle which each element has a unique atomic structure allowing a unique set of peaks on its electro-magnetic emission spectrum (which is the main principle of spectroscopy). The peak positions are predicted by the Moseley’s law with accuracy much better than experimental resolution of a typical Energy dispersive X-ray (EDX) instrument.
Energy dispersive X-Ray spectroscopy analysis – it is defined as an analytical method for the chemical characterization of materials, utilizing the emission of characteristic X-rays from a sample when it is bombarded with high-energy charged particles, resulting in a spectrum that reveals the elemental composition and allows for elemental mapping of the sample.
Energy dissipation – It is the irreversible process of converting kinetic or mechanical energy into heat or other non-recoverable forms. It is a fundamental mechanism used to control destructive forces, absorb vibrations, and prevent catastrophic failures in structural, mechanical, hydraulic, and electrical systems.
Energy dissipation rate – It is the speed at which energy is converted from a useful or mechanical form into an irrecoverable form (like heat or sound) because of the friction, viscosity, or structural deformation.
Energy efficiency – In an industrial plant, energy efficiency is the practice of reducing manufacturing energy consumption levels through a broad range of technologies, methodologies and practices. There are several reasons for the plant management to make the plant become energy efficient which include (i) rising energy costs, (ii) rising inflation rates, (iii) environmental concerns, (iv) to improve competitiveness, and (v) to create economic stability.
Energy efficiency measures – These refer to strategies and techniques implemented in buildings to reduce energy consumption, improve economic performance, and minimize CO2 (carbon di-oxide) emissions. These measures include upgrading heating and cooling systems, enhancing insulation, sealing leaks, and using energy-efficient appliances.
Energy efficiency ratio – It measures an air conditioner or heat pump’s efficiency by dividing its cooling capacity by its electrical power consumption. It operates as a ‘snapshot’ of performance, indicating how effectively a system cools when running at maximum capacity under specific, fixed conditions.
Energy-efficient building – It uses strategic architectural design and smart technologies to minimize power consumption while maintaining a comfortable indoor climate. This concept encompasses ‘net-zero energy buildings’ (NZEB), which generate as much renewable energy on-site as they consume annually.
Energy-efficient building envelope – It is the physical barrier separating a building’s conditioned interior from the external environment. It functions as a multi-layered system designed to minimize energy consumption and maintain occupant comfort by precisely controlling the transfer of heat, air, and moisture.
Energy electrons – These refer to energetic electrons which interact with atoms, leading to either elastic or inelastic collisions, where inelastic collisions can result in the excitation of an atom or its ionization depending on the quantity of energy transferred.
Energy emulsification methods – These refer to high-energy processes utilized to create nano-emulsions, where energy is generated through mechanical devices such as high shear stirrers, high-speed homogenizers, ultrasonicators, and micro-fluidizers, enabling the formation of emulsions with very small droplet sizes.
Energy end use – It refers to the final utilization of energy by consumers (like heating, cooling, or powering machines). It measures the exact quantity of energy delivered to a device to perform useful work, strictly separating the ‘demand’ side from the ‘main’ energy extraction, conversion, and transmission losses. Energy end-use analysis allows professionals to design highly efficient systems by categorizing exactly how, where, and why energy is consumed across different domains.
Energy engineering – It is a multi-disciplinary field focused on designing, optimizing, and managing energy systems. It combines physics, chemistry, and mathematics with environmental science to develop renewable technologies, improve energy efficiency, and reduce carbon footprints.
Energy equation – It is the mathematical formulation of the conservation of energy principle in fluid dynamics, which accounts for different factors such as velocity, temperature, density, and energy sources within a fluid system.
Energy error – It is a metric which evaluates the discrepancy between a theoretically conserved value and an observed or computationally calculated value. Depending on the field, it typically measures the deviation from the law of conservation of energy or the inaccuracy of an energy measurement.
Energy exploration – It refers to the process of searching for and assessing potential new sources of power. It is the foundational phase of the energy industry, encompassing the geological and geophysical surveys needed to locate, map, and estimate the viability of resources like fossil fuels (oil, natural gas, coal) or renewables (geothermal).
Energy feasibility study – It is an investigative assessment which evaluates the technical, financial, and operational viability of a proposed energy project or system before substantial investments are made. It aims to mitigate risk and determine if a project will deliver reliable energy savings and a solid return on investment. These studies act as ‘bankable’ blueprints to help businesses, governments, and developers make confident, data-backed investment decisions.
Energy flexibility – It is the capability of an energy system to adjust its electricity generation or consumption in response to external signals (like price changes or grid conditions). It acts as a shock absorber to stabilize the power grid, maximize the use of renewable energy, and lower utility costs.
Energy flow – It is the quantitative movement and transfer of physical energy through a system, process, or component. It involves energy being transferred as work or heat, and it is evaluated using thermodynamic principles, such as the ‘steady flow energy equation’ (SFEE), to track inputs, outputs, accumulation, and losses.
Energy flux – It is the rate of energy transfer passing through a specific surface area per unit of time. Frequently called ‘energy flux density’, it quantifies how intensely energy moves through a medium or boundary.
Energy flux density – It is the rate of energy transfer per unit area, measured in watts per square meter. It describes how intensely energy (such as heat, sound, or electro-magnetic radiation) flows through or hits a specific surface.
Energy footprint – It measures the total quantity of energy consumed by an individual, organization, product, or system throughout its lifecycle, including both direct energy (electricity / fuel) and indirect energy (embedded in goods / services). It tracks the impact of human activities from production to disposal, serving as a key indicator for sustainability, energy efficiency, and carbon reduction strategies.
Energy formulation – It is a mathematical or structural framework to analyze a system by evaluating its energy states (e.g., kinetic, potential, and thermal) rather than forces. It simplifies complex problems by using scalar values, which are frequently easier to solve than vector-based equations.
Energy-from-waste plant – It is an industrial facility which converts non-recyclable solid waste into usable energy, mainly electricity, or steam, through thermal or biological processes like combustion, gasification, or anaerobic digestion. It serves as an important tool in modern waste management and the circular economy.
Energy functional – It is a mathematical tool which maps a system’s state to a single scalar value representing its total energy. By formulating problems as an energy functional, complex physical or computational states can be modelled, optimized, or minimized by determining the state which needs the lowest quantity of energy.
Energy gain – It is also called net energy gain. It refers to the difference between the total usable energy produced by a system and the total energy invested to create, extract, or initiate that energy.
Energy gap – It is the minimum energy needed to excite an electron from a material’s valence band into its conduction band, enabling it to conduct electricity. In this range, no electron states can exist. It is measured in electron-volts (eV) and determines a material’s electrical and optical properties.
Energy generation technologies – These technologies refer to different methods and systems used to convert different energy sources into electrical energy, including thermoelectric, hydroelectric, solar, wind, ocean, geothermal, nuclear, and fuel cell systems.
Energy grade line – It is a graphical representation of the total energy head, or the sum of pressure head, velocity head, and elevation head, at different points along a fluid flow system. It represents the total energy and always slopes downward in the direction of flow, representing energy loss because of the friction, except where energy is added by a pump.
Energy harvesting – It is the process of capturing, converting, and storing ambient energy from the surrounding environment, such as vibrations, heat, light, and radio waves, into usable electrical power. This method eliminates the need for battery replacements or wired power connections in remote or hard-to-reach hardware.
Energy hybridization – It is the integration of two or more distinct power generation or storage sources into a single, cohesive system. The goal is to maximize efficiency, reduce costs, and ensure a stable, continuous energy supply by using the strengths of each technology to offset their individual weaknesses.
Energy independence – It is the structural capacity of a region to meet its total energy demand using entirely domestic generation.
Energy input – It is the total energy supplied to a system, machine, or process to perform a specific function or achieve a desired state. It represents the initial power required to drive a system, whether that energy is electrical, mechanical, thermal, or chemical. Energy input is foundational across several engineering disciplines.
Energy input rate – It is the amount of energy supplied to a system or device per unit of time. Since it is energy over time, it is physically equivalent to power. It is measured in watts or kilo-watts.
Energy integral equation – It is a simplified mathematical tool used to calculate thermal boundary layer thickness, heat transfer coefficients, and temperature profiles over surfaces.
Energy integration – It is a systematic methodology which optimizes energy consumption, generation, and recovery processes. It involves capturing and reusing excess energy (like waste heat), coordinating different energy pathways (such as electricity, thermal, and fuels), and minimizing reliance on external utilities to improve efficiency and reduce environmental impact.
Energy-intensive industries – These industries are manufacturing and processing sectors where energy consumption represents a high proportion of total production costs (typically above 3 %) of production value). In these sectors, engineering focuses on optimizing thermal processes, recovering waste heat, and reducing greenhouse gas emissions.
Energy issues – These issues refer to the critical economic, social, diplomatic, environmental, and security problems related to the supply and demand of energy resources. They encompass challenges such as energy security, resource optimization, and the impact of energy consumption on ecosystems.
Energy labels – These are informative stickers affixed to products which describe their energy performance, allowing consumers to compare energy efficiency and consumption among similar models. They aim to promote the purchase of more efficient products and encourage manufacturers to develop better energy-saving technologies.
Energy level structure – It defines the discrete, quantized states of potential energy which particles, like electrons, can occupy within an atom, molecule, or solid material. These states determine how materials conduct electricity, absorb light, and react chemically.
Energy load – It refers to the quantity of power consumed by a device or system over a specific period, measured in kilowatt-hours (kWh).
Energy load management – It refers to strategies used to modify and optimize electricity consumption patterns, particularly during peak demand periods, through techniques such as peak clipping, load shifting, and dynamic energy management. These methods aim to reduce demand deficits without the need for additional power generation.
Energy load rate – It is also known as load factor. It is a measure of how efficiently and continuously the consumed energy is utilized.
Energy loss rate – It is the speed at which energy is dissipated, converted to unusable forms (like waste heat), or lost from a system over time. Depending on the discipline, it is defined either as power (energy per unit time, measured in watts) or as a spatial gradient (energy lost per unit of distance).
Energy management – It is the proactive, systematic planning and operation of energy production, distribution, and consumption. Its goal is to maximize energy efficiency, minimize costs, and reduce environmental impact through the use of specialized hardware, software, and optimization techniques.
Energy management approach – Under this approach, the plant management develops procedures and system of recording and analyzing the operating data. The employees are thoroughly trained in these procedures and system. By adopting this approach, there is normally a substantial reduction in the operating mistakes by the operators and the processes run in more stable mode, which in turn helps in the energy conservation. A sound energy management system creates a foundation for positive change and provides guidance for managing energy throughout the plant resulting into continuous improvements towards the conservation of energy. Energy conservation under energy management occurs because of existence of a strong organizational commitment. Energy management system helps to ensure that energy efficiency improvements do not just happen on a one-time basis, but rather are continuously identified and implemented.
Energy management controller – It is a hardware and software system which monitors, coordinates, and optimizes the generation, storage, and consumption of power. It serves as the central brain, balancing energy loads, integrating renewable sources, and reducing costs while maintaining operational stability.
Energy management system – It supports an organization to use energy more efficiently. The organization specifies the requirements for establishing, implementing, maintaining, and improving an energy management system, whose purpose is to enable an organization to follow a systematic approach in achieving continual improvement of energy performance, including energy efficiency, energy security, energy use, and consumption. The system aims to help the organization continually reduce the energy use, and hence the energy costs and the greenhouse gas emissions.
Energy market – It is a structured framework which facilitates the trade, transmission, and balancing of energy resources (such as electricity and natural gas). It matches supply and demand, dictates pricing, and optimizes grid stability.
Energy meteorology – It is a specialized field which applies atmospheric science and weather data to analyze, forecast, and optimize energy production. It bridges meteorology and renewable energy systems, providing the critical data needed to design, operate, and stabilize power grids reliant on fluctuating sources like wind and solar.
Energy metering – It is the process of continuously measuring and recording the total electrical power consumed (or produced) over a specific period. It integrates instantaneous power (P) over time (t) to calculate total energy, which is standardly quantified in kilo-watt-hours (kWh).
Energy methods – These are analytical and computational techniques used to solve structural, mechanical, and dynamic problems by utilizing principles of work and energy (such as kinetic energy, potential energy, and internal strain energy). These methods allow engineers to analyze complex systems, like beams, trusses, and vibrations, without having to solve the governing differential equations of motion simultaneously.
Energy minimization – It is a mathematical and computational optimization process used to find the most stable state of a system, such as the lowest potential energy, stress, or power consumption, by adjusting design variables or spatial configurations until the net forces acting on the system are practically zero.
Energy mix – It refers to the specific combination of main energy sources used to meet the energy consumption and generation needs of a specific region or country. It is typically expressed as a percentage breakdown of resources like fossil fuels, nuclear, and renewables. From an engineering and systems perspective, optimizing the energy mix is a complex challenge focused on balancing supply and demand while minimizing costs and environmental impact.
Energy modelling – It is the process of creating computer-based mathematical simulations of physical systems to predict, analyze, and optimize energy consumption. It evaluates how systems like buildings, industrial plants, or power grids perform, helping engineers reduce costs, improve efficiency, and meet sustainability goals. Depending on the engineering discipline, energy modelling typically falls into two main categories namely building energy modelling (BEM), and energy systems and process modelling.
Energy norm – It is a mathematical measure of a structural system’s total deformation or stress. In finite element analysis (FEA), it quantifies the ‘size’ of the error between theoretical and approximate solutions. By calculating the square root of the system’s strain energy, engineers can identify regions needing mesh refinement.
Energy, nucleation – It refers to the total work needed to create a nucleus, which is the sum of the work needed to form the surface of the nucleus and the work associated with the bulk of the particle. This energy is characterized by opposing contributions from surface and volume terms, influencing the stability and growth of the nucleus.
Energy optimizing furnace – It is a furnace for the primary steelmaking. It is a melting / refining furnace for the production of liquid steel. It is having a scrap pre-heater. The basic principle consists of working with combined submerged and atmosphere oxygen blown in an initial charge containing hot metal, preheated solid scrap and fluxes for slag formation. Scrap is preheated to around 850 deg C to 900 deg C by the sensible heat in the off gas in one or two chambers located above the furnace roof. Blown submerged oxygen reacts with the carbon from hot metal and generates carbon mono-oxide bubbles which travel through the liquid bath to the furnace atmosphere. Here carbon mono-oxide is burnt to carbon di-oxide by the oxygen blown through atmospheric injectors and supersonic lances. The bubbling of carbon mono-oxide generates a very strong stirring action and increases significantly the bath surface. This allows transfer of a good quantity of heat to the bath. The process also constitutes de-slagging and formation of the secondary slag.
Energy optimization model – It is a mathematical framework used to identify the most efficient and cost-effective ways to design, operate, or upgrade energy systems. It systematically minimizes or maximizes an objective function (such as cost or carbon emissions) under specific technical constraints (like fluctuating demand or equipment limits).
Energy payback time – It is the duration an energy system is required to operate to generate a quantity of renewable or clean energy equal to the total life-cycle energy needed to produce, install, maintain, and decommission it. It measures the net-energy efficiency and sustainability of power systems.
Energy performance – It is the quantitative measurement of how efficiently a system, building, or process converts energy into useful output. It evaluates energy consumption against established baselines to optimize efficiency, minimize waste, and meet sustainability standards. The concept forms the bedrock of modern engineering and facilities management. It operates through several core components.
Energy performance contracting – It is a financial and engineering model where an ‘energy service company’ (ESCO) designs, implements, and maintains energy-efficiency upgrades for a customer. The unique feature of this contract is that the energy service company’s repayment is directly tied to the achieved cost reductions.
Energy planning – It is the process of developing long-term policies and systems to manage energy resources, optimize conversion technologies, and balance supply with demand. It evaluates technical, economic, and environmental criteria to ensure sustainable, efficient, and cost-effective energy use across infrastructures. Energy planning combines thermodynamic principles with systems analysis to create actionable strategies.
Energy planning tools – These are computational instruments to design, optimize, and forecast future energy systems. These tools allow engineers to analyze the production, distribution, and consumption of energy to meet demand while minimizing costs, optimizing resources, and achieving sustainability or climate-action objectives. These tools typically fall into specific engineering and economic modeling categories.
EnergyPlus – It is a free, open-source whole-building energy modeling engine used by engineers and architects to simulate energy consumption (heating, cooling, lighting, and ventilation) and water use. It models complex building physics, such as radiant systems and thermal comfort.
Energy-plus building – It produces more energy from renewable energy sources, over the course of a year, than it imports from external sources. This is achieved using a combination of micro-generation technology and low-energy building techniques, such as passive solar building design, insulation and careful site selection and placement.
EnergyPlus simulation – It is a whole-building energy modeling process which predicts a structure’s energy consumption, water usage, and thermal comfort. It uses physics-based algorithms to simultaneously calculate heating, cooling, lighting, and HVAC (heating, ventilation, and air conditioning) system performance based on building geometry, materials, and local weather data.
Energy policy – It is a strategic set of guidelines, regulations, and standards governing how energy is generated, distributed, and consumed. It uses data and technology to optimize efficiency, manage costs, reduce emissions, and integrate renewable resources.
Energy price model – It is a mathematical or algorithmic framework which simulates and predicts future energy costs. It integrates operational constraints, historical data, and market dynamics, such as supply, demand, and carbon pricing, to balance power systems, optimize resource deployment, and manage financial risk.
Energy principle – It typically refers to the work-energy theorem. It states that the net work done by all forces acting on a system is exactly equal to the change in its kinetic energy. It provides a fast, powerful way to solve complex dynamics and structural problems without calculating acceleration or time.
Energy problem – It is the fundamental challenge of satisfying a growing global demand for power without depleting limited resources or causing environmental harm. It needs optimizing how to produce, transmit, store, and consume energy while minimizing waste and carbon emissions.
Energy product – It is the product of the flux density and the field strength at any point of a de-magnetization curve for a permanent magnet. The maximum value of the product is called (BH)max. It is directly related to the stored energy per unit volume of the material. The units of (BH)max are joules per metre.
Energy production – It is the process of extracting and converting primary energy sources (e.g., coal, natural gas, solar, wind, nuclear) into usable, secondary energy forms like electricity or refined fuels. It relies on maximizing conversion efficiency, optimizing output yield, and minimizing thermal or environmental losses.
Energy project – It is a temporary initiative to develop, modify, or manage energy resources or infrastructure. It involves applying scientific and mathematical principles to convert natural resources into useful energy (like electricity, thermal power, or fuel) while maximizing efficiency and economic viability.
Energy quality – It defines how easily a specific form of energy can be converted into useful work. Quantitatively, it is expressed as the ratio of exergy (maximum usable work) to total energy (or enthalpy). Higher quality means higher versatility and work potential.
Energy quantity – It is the scalar physical property which measures a system’s capacity to perform work or produce heat. Governed by the first law of thermodynamics, it is a conserved quantity which can be neither created nor destroyed, but only converted between different forms (such as kinetic, potential, or thermal).
Energy rate balance – It is derived from the first law of thermodynamics. It is an accounting principle for open systems which equates the rate at which energy enters and leaves a system. It is formally defined as ‘rate of energy in – rate of energy out = rate of energy accumulation’.
Energy ratio – It is a performance metric which measures the relationship between energy output (or useful work) and energy input. Expressed as ‘ER = Eout / Ein’, it is a universal concept used to evaluate system efficiency, sustainability, and dynamic responses across different engineering disciplines.
Energy recovery device – It is a system which captures and reuses waste energy. such as heat, pressure, or kinetic force, which otherwise is to be exhausted from a process. By recycling this energy, energy recovery devices (ERDs) dramatically improve overall system efficiency, reduce operational costs, and lower environmental impact across multiple industries.
Energy recovery ventilator – It is a mechanical HVAC (heating, ventilation, and air conditioning) component which continuously replaces stale indoor air with fresh outdoor air while recovering both sensible (heat) and latent (moisture) energy from the exhaust air. It precools / dehumidifies incoming air in the summer and prewarms / humidifies it in the winter to optimize efficiency.
Energy reduction – It refers to the practice of decreasing energy consumption or usage across different units of the organization, leading to benefits like lower specific energy consumption, environmental sustainability, and reduced greenhouse gas emissions. Targets for energy consumptions are set base on industry norms.
Energy refurbishment – It refers to the process of energetically renovating buildings to improve energy efficiency, reduce dependence on fossil fuels, and comply with guidelines set by regulatory directives. This concept is related to the implementation of different energy conservation measures (ECMs) aimed at achieving substantial energy savings and reducing greenhouse gas emissions.
Energy release rate – It is the rate at which total potential energy is made available for the growth of a crack per unit of newly created crack surface area. It is a foundational parameter in fracture mechanics used to predict material failure and structural fatigue.
Energy renovation – It refers to the systematic process of upgrading an existing structure to drastically reduce energy consumption, minimize carbon emissions, and improve occupant comfort. It involves analyzing and redesigning a building’s thermal envelope and mechanical systems using cost-effective, sustainable engineering interventions.
Energy requirements – These requirements define the total quantity of energy (mega-joules, kilo-watt hours, etc.) needed to operate a system, produce a functional unit of a product, or complete a specific process, incorporating inputs for production, transportation, and equipment. It covers both useful energy and inefficiencies (losses).
Energy research and development – It is the systematic process of innovating, designing, and testing new technologies to optimize energy production, improve efficiency, and reduce environmental impact. It translates scientific concepts into scalable, practical solutions like renewable systems and advanced grids.
Energy resource – It is a naturally occurring or artificial physical system, material, or phenomenon which can be harnessed to produce useful power, heat, or work. These resources are the main inputs used by engineers to design systems for electricity generation, transportation, and manufacturing.
Energy-restricted machines – These are also known as energy-limited or load-limited machines. These are forging equipment where the total deformation during a stroke is determined by the total energy available, rather than a fixed distance or position. These machines, which include hammers and several types of screw presses, are defined by their ability to provide a specific maximum quantity of energy in a single blow or cycle.
Energy retrofit measure – It is a specific technical intervention or upgrade applied to an existing building or system to improve its energy efficiency, reduce consumption, and lower greenhouse gas emissions. It aims to optimize operational performance without compromising the comfort or utility of the space.
Energy return on investment – It is a thermodynamic metric used in engineering and systems analysis to measure the efficiency of an energy-producing process. It calculates the ratio of usable energy delivered to society divided by the total energy directly or indirectly needed to extract, process, and deliver that energy.
Energy saving conveyor belt – Energy saving conveyor belt applies the cover rubber to minimize the transformation of rubber by idler. This conveyor belt can improve in reducing the electrical power needed operate the conveyor belt by decreasing the loss of energy.
Energy savings – It is the reduction of energy consumption needed to achieve the same level of service, output, or comfort. It is achieved by optimizing processes, upgrading to high-efficiency equipment, recovering waste heat, and reducing losses without compromising overall operational performance.
Energy scenario – It is a structured, quantitative, and narrative model used to explore and map out alternative future states of an energy system. It evaluates the production, distribution, and consumption of energy against changing economic, environmental, and technological variables to guide policy and infrastructure development.
Energy security – It is the capability of an infrastructure system to reliably supply, transmit, and deliver energy to meet societal and economic demands—even when subjected to extreme disruptions or cyber-physical attacks. It is measured by an infrastructure’s reliability, robustness, and rapid-recovery metrics. It is the engineering resilience of the system to guarantee an uninterrupted, affordable, and stable supply, even when subjected to physical, cyber, or geopolitical shocks.
Energy separation – It refers to the spontaneous division of a single gas or fluid stream into distinct high-temperature (high-energy) and low-temperature (low-energy) regions. In process and chemical engineering, energy separation describes the expenditure or management of energy to separate components from a mixture.
Energy service organization – It is a commercial organization which provides comprehensive energy solutions, including facility upgrades, retrofitting, and energy supply. Crucially, these organizations assume the financial risk of a project by linking their compensation directly to the actual energy savings achieved, frequently through energy performance contracting (EPC).
Energy shift – It normally refers to one of three concepts. The first is energy transition which means industrial infrastructure from fossil fuels to renewables. The second is frequency energy shift, which is a diagnostic technique for detecting and monitoring mechanical faults (e.g., in bearings) by analyzing frequency bands. The third is phase shift, which is the difference between the peaks and troughs of two sinusoidal waves, which is critical in electrical power engineering.
Energy simulation – It is the process of modelling a building’s energy use and performance based on input parameters to predict energy consumption and assess potential energy savings from retrofit measures. It serves as an important tool in evaluating the effectiveness of different energy efficiency strategies within the context of building design and renovation.
Energy sources – They are materials or elements which can be used to produce energy. They are forms of potential energy which can be used to perform work, such as to generate heat, light, or power. They can be classified as primary energy sources and secondary energy sources. Primary energy sources take several forms, including nuclear energy, fossil energy such as oil, coal and natural gas, and renewable sources like wind, solar, geothermal and hydropower. These primary sources van be converted to electricity, a secondary energy source, which flows through power lines and other transmission infrastructure to industry.
Energy spectral density – It defines how the total energy of a finite-duration signal is distributed across different frequencies. It is typically calculated as the squared magnitude of the signal’s Fourier transform.
Energy spectrum – It defines how energy is distributed across a range of frequencies, wave-lengths, or energy levels. Depending on the engineering discipline, it is an important tool used to analyze signals, evaluate structural vibrations, or measure radiation.
Energy standard – It refers to a set of mandatory or voluntary guidelines, regulations, and specifications designed to control, measure, and minimize energy consumption. These bench-marks promote sustainability, drive continuous efficiency improvements, and regulate the design, operation, and performance of energy systems.
Energy state – It defines the specific configuration of total mechanical or thermo-dynamic energy possessed by a system at any given moment.
Energy storage – It is the capture and containment of energy in one form to be converted and drawn upon later as a different or more convenient form. It is an important mechanism for load balancing, managing fluctuating energy demands, and integrating intermittent renewable resources into the power grid.
Energy storage and conversion – It is the discipline focused on capturing energy in one form, transforming it into a more convenient or economical state for storage, and releasing it as usable power later. It bridges the gap between fluctuating energy production and consumer demand to optimize efficiency and sustainability.
Energy storage applications – These refer to technologies and systems which manage and store energy for later use, improving the efficiency and reliability of electric grids and supporting the integration of renewable energy sources like wind and solar.
Energy storage capacity – It is the total usable energy an accumulator or storage system can hold and deliver. It is defined as the mathematical product of the discharge power and the time it can be sustained, measured in watt-hours or joules.
Energy storage demand – It is the engineering requirement for devices to capture, hold, and release energy. It defines the necessary capacity (kilo-watt hour / mega-watt hour), discharge duration, and power ratings (kilo-watt / mega-watt) needed to bridge gaps between energy supply and user consumption, ensuring grid stability and integrating intermittent renewable sources.
Energy storage density – It is the quantity of energy a system or material can hold relative to its unit of mass or volume. It is a critical engineering metric used to evaluate, compare, and design storage solutions across electric vehicles, consumer electronics, and grid-scale power systems.
Energy storage economics – It is the financial analysis of capturing and releasing energy (like electricity or heat) to balance supply and demand, optimize grid efficiency, and maximize profitability. In engineering, it marries system thermodynamics and hardware specifications with capital costs, operational lifespans, and market value streams to determine the optimal deployment technology.
Energy storage element – It is a physical or dynamic component which captures, retains, and releases energy over time. These elements bridge the gap between energy supply and demand, improving system efficiency, grid stability, and operational reliability across different domains.
Energy storage inductor – It is a passive electrical component which resists changes in current by temporarily storing energy in a magnetic field. Normally built as a coil of wire, it regulates power in electronic circuits by absorbing energy during current spikes and releasing it to prevent drops.
Energy storage modelling – It is the process of creating mathematical and computational representations of energy storage systems (like batteries or pumped hydro) to predict performance, thermal stability, and cycle life. It evaluates variables like power limits, capacity, and efficiency to optimize system deployment.
Energy storage solution – It is a system which captures and retains energy for later use. It enables power stabilization, load balancing, and renewable integration. Engineering these solutions involves selecting, sizing, and integrating physical technologies with power electronics and control algorithms to match specific operational profiles.
Energy storage system (ESS) control – It refers to the hardware and software architectures designed to manage, monitor, and optimize energy capture, storage, and discharge. It bridges the gap between raw physical assets, such as batteries, flywheels, or hydrogen electrolyzers, and dynamic energy demands, ensuring system stability, grid reliability, and peak efficiency.
Energy storage system (ESS) modelling – It is the process of creating mathematical and computational representations of storage technologies (like batteries) to simulate their behaviour. It defines how to predict performance, thermal stability, degradation, and state-of-charge under dynamic operating conditions.
Energy storage system (ESS) optimization – It refers to the use of mathematical models and algorithms to design and control energy buffers, maximizing efficiency, minimizing costs, and supporting grid stability. It fine-tunes system hardware and operations while respecting physical and economic constraints.
Energy storage technology – It refers to the methods and equipment used to capture energy produced at one time and store it for later use. These systems are designed to balance supply and demand, bridge the gap between intermittent renewable generation (like wind and solar) and grid stability, and provide localized power. These technologies are classified based on the physical or chemical principles they use to capture and release energy.
Energy sustainability – It is the systemic design and management of energy systems to meet current societal and industrial demands. It optimizes the entire lifecycle of energy, from harvesting and conversion to transport and utilization, without depleting natural resources or compromising the ability of future generations to meet their needs. Sustainability is evaluated across four core pillars namely environmental impact, economic viability, technical reliability, and social equity.
Energy system analysis – It is the process of quantitatively modeling, simulating, and optimizing complex energy infrastructures (such as power grids, generation plants, and storage facilities). It applies mathematical and economic principles to evaluate how technologies produce, convert, and distribute energy to meet societal demands.
Energy system analysis models – These are computational frameworks which simulate the complex interactions between energy supply, demand, and environmental impacts. These models use quantitative methods to evaluate technologies, infrastructure, and policies, helping stakeholders identify cost-effective, sustainable, and reliable pathways for energy generation and consumption.
Energy system audit – It is a systematic inspection, survey, and analysis of energy flows within a building, process, or system to identify opportunities for reducing energy consumption and costs without affecting production or comfort. It acts as a diagnostic tool, providing a technical report with actionable recommendations for improving energy efficiency.
Energy system models – These are mathematical and computational representations used to simulate the complex interactions between energy supply, demand, and the environment. These models analyze technology configurations, infrastructure, and economic costs to optimize system feasibility, maximize energy efficiency, and minimize greenhouse gas emissions.
Energy system operation – It is the real-time monitoring, control, and optimization of integrated energy networks. It ensures the continuous balance between energy supply and end-user demand while maximizing efficiency, reliability, and economic viability across power generation, transmission, and distribution.
Energy system planning – It is the process of evaluating, designing, and optimizing long-term strategies for energy production, transmission, and consumption. It utilizes mathematical modeling to balance technical, economic, and environmental factors, ensuring reliable energy supply while minimizing costs and carbon emissions.
Energy systems – These are well-engineered systems designed to supply energy services, including power generation, heating, cooling, and domestic hot water, to end users. They encompass primary energy sources, energy conversion management, and distribution to different sectors such as residential, commercial, and industrial sectors.
Energy systems engineering – It is a multi-disciplinary field focused on designing, optimizing, and managing the entire lifecycle of energy. It encompasses the generation, conversion, transmission, distribution, and efficient end-use of energy across residential, commercial, and industrial sectors.
Energy technology – It is an interdisciplinary field focused on the extraction, generation, conversion, storage, and distribution of energy. It applies physics, chemistry, and mathematics to create efficient, safe, and sustainable power systems which meet human and economic needs while minimizing environmental impacts.
Energy transfer function – It is a mathematical model which defines how a system distributes, converts, or dissipates energy from an input source to an output load. It typically represents the ratio of the system’s output power or energy state relative to the input over a specific frequency domain.
Energy transfer model – It is a mathematical or conceptual framework used to track how energy is exchanged, stored, and transformed between systems. Based on the first law of thermodynamics, these models define energy interactions, mainly as heat, work, and mass flow, while enforcing the law of conservation of energy ‘Ein-Eout = delta E’. Engineers rely on these models to design efficient thermodynamic cycles, structural systems, and electronic components. The methodology breaks down into specific components, mechanisms, and modeling techniques.
Energy transfer rate – It is the quantity of energy transferred from one system or location to another per unit of time. It is synonymous with power, where 1 joule per second equals 1 watt. It governs how efficiently heat, work, or mass is exchanged.
Energy transformation – It is the change from one form of energy, such as the energy embodied in fossil fuels to another form of energy such as electricity.
Energy transition – It is the structural shift from fossil-based energy systems to sustainable, renewable sources (like solar, wind, and hydrogen) to achieve net-zero carbon emissions. It needs redesigning how energy is generated, transmitted, and consumed to maximize efficiency, grid resilience, and sustainability.
Energy transmission – It is the bulk movement or transfer of energy from its point of generation (like a power plant) to the location where it is utilized. It fundamentally branches into two main disciplines namely electrical power transmission and mechanical energy transmission.
Energy transmission system – It refers to the infrastructure and equipment used to transport energy from its source to points of consumption or application. Depending on the field, it is categorized as electrical (transporting power) or mechanical (transferring physical force and torque).
Energy transportation – It refers to the movement of energy resources (like electricity, oil, or gas) from production to consumers, or the mechanical energy required to move people and goods. It blends power transmission, thermodynamics, and fluid dynamics to design safe, efficient delivery systems.
Energy upgrade – It is the strategic improvement of a system or infrastructure to improve energy efficiency, reduce consumption, and lower carbon emissions. It relies on data-driven approaches, like cost-benefit analyses and financial return on investment (ROI) metrics, to optimize resource use across buildings, industrial processes, or grids. Energy engineers approach these upgrades using a systematic, step-by-step framework to ensure maximum efficiency and sustainability.
Energy usage – It refers to the total quantity of energy consumed by a device, system, or facility over a specific period. It is distinct from power (the rate of energy transfer) and is calculated by multiplying operational power by time.
Energy use behaviour – It refers to the human actions and decisions which affect the utilization, consumption, and conservation of energy within a built environment. It combines physical, technical, and psychological factors to understand how occupants interact with systems to achieve desired services.
Energy use in buildings – It refers to the total energy consumed during a building’s operational lifecycle. It mainly encompasses the energy needed for ‘heating, ventilation, and air conditioning’ (HVAC), lighting, water heating, and appliances to maintain a safe and comfortable indoor environment.
Energy valley – It refers to a low-energy state in a potential energy landscape, where a system can reside, surrounded by higher energy mountains and connected by passes to other valleys. Energy valley is mathematically known as the algorithm models unstable, high-energy particles decaying or shedding mass / energy to settle into a stable state.
Energy valley optimizer – It is an AI (artificial intelligence) algorithm used for mathematical and complex engineering optimizations. It is inspired by advanced physics principles, specifically how the subatomic particles adjust their neutron-proton ratios and undergo decay to reach stability.
Energy values – These values refer to the quantitative measures of energy associated with heat and work flows, which are absolute for these flows but relative for material flows, needing reference levels for accurate evaluations such as enthalpy.
Energy viability – It is the evaluation of whether an energy system or technology can reliably, efficiently, and profitably produce, store, and deliver power. It is determined by analyzing technical performance, life-cycle energy output against inputs, and economic sustainability.
Energy vision – It is a strategic roadmap defining the future state of energy systems. It focuses on reforming infrastructure by integrating renewables, improving grid resiliency, and maximizing efficiency through smart technologies to achieve sustainability and net-zero emissions. Energy visions serve as actionable master plans guiding research, development, and implementation.
Energy waste costs – These costs quantify the financial and operational burden of consuming energy beyond the theoretical minimum required to execute a process or maintain production. It is the economic penalty paid for inefficiencies, equipment degradation, or poor system design.
Energy yield – It typically refers to the total usable energy produced by a power system (like a solar or wind farm) over a specific period, or it can describe the energy returned during a material’s life-cycle.
Energy yield ratio – It is a fundamental metric which measures the ratio of total life-time energy output of a power system to the total primary energy invested to manufacture, construct, and operate it. It is mainly used in lifecycle and economic analyses to assess the viability and environmental sustainability of power-generating systems. It is the measure of how many times the energy invested in a wind turbine is returned or paid back by the system throughout its entire life.
Enforcement – It consists of those activities which compel and / or force adherence to statutory requirements.
Enforcement authority – It is the statutory or regulatory body designated to ensure that designs, manufacturing processes, and infrastructure projects comply with established safety, environmental, and technical laws. These bodies have the legal power to mandate standards, conduct inspections, and issue penalties or stop-work orders.
Enforcement order – Under the different statutory regulations, it is an enforcement order (a legal document) requiring an organization to stop an activity, fix a problem, or restore the environment.
Enforcement response – It consists of the actions taken in response to a determination of non-compliance in order to remedy the non-compliance, deter future non-compliance, or punish the offender.
Engine base – It refers to the foundational structure (frequently an engine block, oil pan, or sub-frame) which supports the moving parts of an internal combustion or electric motor. It provides structural rigidity and absorbs torque and vibration.
Engine case – It is frequently called an engine block or crankcase. It is the main structural housing which encloses, protects, and supports important internal mechanisms like the crankshaft, pistons, and connecting rods. It provides rigidity, seals in lubricating fluids, and manages the extreme pressures generated during operation.
Engine combination – It is the specific pairing of hardware components, induction systems, and calibrations designed to produce a targeted power output and efficiency. This applies across multiple engineering disciplines, focusing on how different mechanisms, software modules, or power units interact to achieve optimal overall system performance.
Engine concept – It refers to innovative designs and technologies in automotive propulsion aimed at improving combustion efficiency, reducing pollutant emissions, and improving engine performance. Examples include engine downsizing, homogeneous charge compression ignition (HCCI), and reactivity-controlled compression ignition (RCCI), which utilize different fuel characteristics and combustion strategies.
Engine connecting rod – It is a critical component which connects the piston to the crankshaft in an internal combustion engine, allowing the conversion of linear motion into rotational motion. It plays a substantial role in the overall performance of the engine, including factors such as torque and reaction forces.
Engine control – It refers to the systems and algorithms used to regulate, monitor, and optimize an engine’s operation. It relies on control theory to process data from different sensors and adjusts mechanical parameters in real-time for ideal power, fuel efficiency, and emissions.
Engine control module – It is frequently called the engine control unit (ECU). It is the central onboard computer in modern vehicles. It continuously gathers data from sensors to regulate fuel injection, ignition timing, and air intake, optimizing performance, fuel efficiency, and emissions.
Engine control unit – It is an embedded electronic system which serves as the ‘brain’ of an internal combustion engine. It continuously monitors critical engine parameters, such as air-fuel ratio, engine speed, and temperature, to optimize performance, maximize fuel efficiency, and minimize exhaust emissions.
Engine cooling – It is the engineering process of regulating an engine’s temperature to prevent thermal damage and maintain optimal efficiency. It manages the massive waste heat generated by combustion and friction using fluid circulation or forced airflow to transfer heat away from critical metal components into the atmosphere.
Engine cost – it refers to the comprehensive financial and resource expenditure tied to the design, manufacturing, operation, and life-cycle of a mechanical engine (such as an internal combustion engine, jet engine, or electric motor). It utilizes cost engineering methodologies.
Engine cycle – It is the fundamental sequence of thermodynamic processes, such as compression, combustion, expansion, and exhaust, which an engine repeats to continuously convert energy into usable mechanical work or thrust. Different engineering applications rely on specific cycles to optimize for power, efficiency, or operational demands.
Engine cylinder – It is the central working chamber in a reciprocating engine where the piston moves back and forth. It confines the expanding gases from the combustion of fuel and air, translating this pressure into mechanical energy.
Engine data – It refers to the performance charts or data necessary for estimating engine performance, including thrust settings, specific fuel consumption (SFC), and the effects of altitude and speed on engine parameters. This data is essential for conducting aircraft performance calculations and may be derived from manufacturers or predictions based on similar engine types.
Engine design – It is the iterative industrial process of developing and configuring a motor to convert thermal, electrical, or chemical energy into usable mechanical work. It needs optimizing subsystems like thermodynamics, fluid mechanics, and structural mechanics to achieve strict targets for power, fuel efficiency, and emissions.
Engine designer – Engine designer is a specialized mechanical engineer who conceptualizes, develops, and tests propulsion systems and power generation units (such as internal combustion engines, electric power-trains, or gas turbines). They transform technical specifications into buildable, efficient, and reliable engines for different applications.
Engine design process – It is a complex industrial procedure which optimizes interactions among engine sub-systems to meet specific performance, durability, packaging, and cost targets while adhering to strict regulatory requirements. It is a highly iterative cycle involving continuous analysis, prototyping, and testing.
Engine developers – They are professionals who focus on optimizing engine performance by balancing fuel consumption, emissions, and response behaviour while adapting technologies to meet evolving testing and operational requirements.
Engine development – It is the systematic process of planning, designing, testing, and optimizing an engine system. It translates vehicle or industrial requirements into finished engine specifications, carefully balancing performance, fuel efficiency, emissions, durability, and cost. The development life-cycle of an engine typically follows a structured engineering pipeline.
Engine downsizing – It is the automotive practice of replacing a larger, naturally aspirated engine with a smaller, more fuel-efficient one, while using technologies like turbo-charging or super-charging to maintain or even improve power output.
Engine drive – It is the mechanism or linkage through which an engine powers a machine or vehicle. It translates the rotational energy generated by the engine into usable work, such as turning wheels, spinning propellers, or operating heavy machinery.
Engine-driven generator – It is a combined unit (frequently called a genset) which uses an internal combustion engine, such as a diesel or gas turbine, to convert chemical energy into mechanical energy, which an alternator then converts into electrical energy. An engine-driven generator operates as an integrated system, coupling a prime mover with an electrical generating unit.
Engine durability – It is an engine’s ability to operate reliably over its expected life-span without needing a major rebuild or overhaul because of the wear. It measures structural strength against cumulative operational loads like friction, thermal stress, and vibration.
Engine dynamometer – It is a testing device used to measure an internal combustion engine’s torque and rotational speed (revolutions per minute, rpm). By coupling directly to the engine’s driveshaft, it calculates instant horsepower, allowing engineers to evaluate, tune, and trouble-shoot engine performance under highly controlled, simulated loads.
Engine efficiency – It refers to the ratio of useful work output from an engine to the energy input, typically expressed as a percentage. This concept is important in understanding how effectively an engine converts fuel into mechanical energy and directly relates to the performance and environmental impact of different engines, including those found in vehicles and power plants.
Engineer – An engineer is a trained professional who applies scientific principles, mathematics, and creativity to design, build, and maintain structures, machines, systems, and processes to solve complex problems. They bridge the gap between scientific discovery and practical application, improving efficiency and safety while operating under constraints like cost and regulations.
Engineered cementitious composites – These are fibre-reinforced cementitious materials which typically contain around 2 % fibres by volume and no coarse aggregate, allowing for improved ductility and minimized crack widths. These composites are suitable for applications needing thin layers, contributing to more durable and sustainable structures.
Engineered construct – It is a physical, or digital structure deliberately designed and manufactured using scientific principles, mathematical calculations, and technical specifications, rather than relying on natural formation or empirical trial-and-error.
Engineered device – It is a specifically designed mechanism, tool, or system which manipulates physical, chemical, or biological processes to achieve a controlled, predictable outcome. It moves beyond basic or mass-produced commodities to incorporate custom requirements, scientific principles, and highly optimized functions.
Engineered geo-polymer composites – These are sustainable, high-performance construction materials which combine geo-polymer binders with short reinforcing fibres. By replacing traditional, carbon-intensive Portland cement with industrial by-products, engineered geo-polymer composites (EGC) achieves very good tensile ductility, crack-control, and high compressive strength with up to 80 % lesser carbon emissions.
Engineered nano-particles – These are intentionally manufactured materials ranging from 1 nano-meter to 100 nano-meters in size. By manipulating matter at this atomic scale, engineers create particles with unique physical, and chemical, properties (like increased conductivity) which differ vastly from their larger, bulk-scale counterparts.
Engineered plastic – It is a material which has been made by specific design and through use of particular monomers and monomer sequences to produce a plastic with desired properties, possibly for a specific application.
Engineered safety features – These are engineered systems which are important to the safety of the plant. These systems relate to shutting down the reactor, provision of cooling, mitigating the effects of a loss of reactor coolant accident (LOCA), or minimizing offsite release.
Engineered system – It is a system designed or adapted to interact with an anticipated operational environment to achieve one or more intended purposes while complying with applicable constraints.
Engineered valve – It is a custom-designed flow-control device built for extreme, critical, or highly specialized applications. Unlike mass-produced standard valves, they are tailored with specific materials, geometries, and seals to handle harsh conditions like extreme temperatures, corrosive chemicals, or abrasive powders.
Engineering – It is the practice of using natural science, mathematics, and the engineering design process to solve technical problems, increase efficiency and productivity, and improve systems. Modern engineering comprises several sub-fields which include designing and improving infra-structure, machinery, vehicles, electronics, materials, and energy systems.
Engineering adhesives – These are advanced, high-strength synthetic polymers used to join primary and secondary load-bearing structures. Unlike standard glues, they distribute mechanical stress evenly across the joint, provide environmental and chemical resistance, and can bond dissimilar materials like metals, plastics, and composites without mechanical fasteners.
Engineering alloys – These are metallic mixtures designed to have superior mechanical, physical, and chemical properties. These alloys combine a base metal with other elements to achieve specific performance traits like improved strength, corrosion resistance, or high-temperature stability. Majority of the industrial metal components are alloys.
Engineering analysis – It is the process of breaking down complex engineering systems or problems into smaller, manageable parts. By applying scientific principles, mathematical modelling, and physical laws, engineers study these components to predict system behaviour, optimize designs, and ensure safety, reliability, and performance before physical prototyping.
Engineering application – It is the practical use of scientific, mathematical, and technical principles to solve real-world problems. It translates theoretical engineering designs into functional physical products, materials, or systems across several industries.
Engineering behaviour – It refers to how a material, system, or structure responds to external forces, loads, and environmental conditions. It is the fundamental measure of a component’s stability, durability, and performance under specific operating scenarios.
Engineering brick – It is a highly dense, strong clay brick manufactured to achieve exceptional compressive strength and very low water absorption. Unlike standard aesthetic facing bricks, they are mainly specified by structural and civil engineers for their technical performance in demanding, load-bearing, and moisture-exposed environments.
Engineering calculation – It is the systematic process of applying mathematical equations, physical principles, and empirical data to solve technical problems, design systems, and verify safety. It is the core framework engineers use to ensure that structures, machines, and products are reliable, efficient, and built to code. These calculations serve as the bridge between theoretical concepts and physical reality, translating variables like load, stress, and energy into actionable dimensions.
Engineering ceramics – These are also known as advanced, technical, or fine ceramics. These are highly pure, man-made inorganic and non-metallic materials engineered for maximum performance in demanding applications. They are valued for extreme hardness, heat tolerance, wear resistance, and chemical stability, but remain highly brittle. Engineering ceramics can be categorized into functional ceramics and high-strength structural ceramics. These ceramics are frequently characterized by their brittleness and impressive material strength, but prone to fracture because of the small defects in their micro-structure.
Engineering component – It is a distinct, identifiable building block of a larger system or assembly. It performs a specific function, such as transmitting power, supporting a load, or executing a process. and interacts with other parts through defined interfaces. Engineering component has one or more functions namely to support a load, to contain a pressure, to transmit heat, and so forth. These components, while in service, are subjected to a variety of loading.
Engineering controls – A category of hazard control which uses physical / engineering methods to eliminate or minimize the hazard. Examples of engineering controls include ventilation, isolation, elimination, enclosure, substitution and design of the work-place or equipment.
Engineering data book – It is a concise, highly structured technical reference guide which provides professionals and students with necessary formulas, charts, materials data, and mathematical tables. Unlike comprehensive textbooks, it acts as a rapid, on-the-job pocket reference.
Engineering document management system – It is specialized software designed to centrally create, store, track, and share complex engineering files, such as computer-aided design (CAD) drawings and BIM (building information modelling) models. It acts as a single source of truth, optimizing workflows and ensuring teams only access the correct, most up-to-date revisions.
Engineering designers – They are professionals who blend technical engineering knowledge with creative problem-solving to conceptualize, develop, and test new products or systems. They act as the bridge between theoretical design and functional manufacturing, ensuring that an idea is safe, cost-effective, and works as intended. They engage in systematic and purposeful activities aimed at solving important problems through a structured design process, which is iterative and collaborative, and involves using technical knowledge while navigating several constraints.
Engineering design problem – It refers to complex and often open-ended challenges which does not have unique answers, needing creative solutions which satisfy different requirements. These problems differ from traditional textbook problems, as they can involve multiple acceptable designs and necessitate an expanded problem-solving approach. It is the initial phase of the engineering design process. It involves identifying a specific need, establishing goals, and outlining the needs and constraints that a successful solution is required to satisfy. A clearly articulated problem serves as the foundation for all subsequent work. It prevents engineers from wasting time on the wrong issues and ensures that the final design is feasible, functional, and user-centred.
Engineering design process – It is a structured, systematic approach that engineers use to solve problems and create innovative solutions. It is a series of steps, often iterative, that involves identifying a problem, brainstorming solutions, designing a prototype, testing and refining, and ultimately, creating a final product or process.
Engineering design specification – it is a detailed description of the intended and unintended uses which product is going to be put to, a list of any special features needed or desired, and a detailed list of the functional requirements with qualitative or quantitative goals and limits for each. It is also known as product design specification.
Engineering discipline – It refers to a field of study which focuses on understanding how technology works, innovating new solutions, and creating new inventions based on deductive and analytic thinking. It is the designing, testing and building of machines, structures and processes using mathematics and science. It has several branches such as civil, electrical, mechanical, and metallurgical.
Engineering document – It is a formalized record detailing a product or system’s design, development, and implementation. It captures the specific ‘why’ and ‘how’ behind a build, providing stakeholders, such as engineers, manufacturers, and clients, with the precise specifications, calculations, and standards needed to safely build and maintain the project.
Engineering drawing – It is a two-dimensional representation of three-dimensional objects. In general, it provides necessary information about the shape, size, surface quality, material, and manufacturing process, etc. of the object. It is the graphic language from which a trained person can visualize objects. Engineering drawing is called the universal language of engineers. It is also known as technical drawing. It is an effective way of communicating technical ideas and is a necessary tool in engineering design where the majority of the design processes are graphically based. Engineering drawings are used in the design process for visualization, communication, and documentation.
Engineering, English units – These units represent a system of measurement. These are a system defined by feet (length), pounds-mass (mass), and pound-force (force). It is a ‘foot-pound-second’ system where, unlike International System of Units (SI), force and mass are distinct base units, needing a dimensional constant for calculation. Because of this distinction, Newton’s second law (F=ma) incorporates a dimensional conversion constant.
Engineering equation solver – It is a commercial software package used by engineers to numerically solve large, complex systems of linear, non-linear, and differential equations. It is widely used in thermodynamics, fluid mechanics, and heat transfer because of its massive, built-in property database for fluids and materials.
Engineering equation solver software – It is software normally used to simulate thermal systems, such as absorption chillers, which utilizes an iterative method to solve a set of equations.
Engineering ethics – It consists of the moral principles and standards of conduct which guide engineers in their professional responsibilities, particularly concerning the potential impact of their actions on society and the environment. It emphasizes the importance of honesty, integrity, and accountability in engineering practices to ensure the welfare of the public.
Engineering facilities – These facilities refer to the physical buildings, infrastructure, and technical spaces equipped to support engineering design, testing, manufacturing, or maintenance operations. They range from heavy manufacturing plants and oil refineries to high-tech laboratories and data centres, which are engineered for safety, efficiency, and operational reliability.
Engineering handbook – It is a reference book containing factual information such as definitions, formulas, physical constants, chemical properties, materials properties, and so on. It is a reference or operational guide used by engineers. It typically falls into one of two categories namely a technical reference (containing formulas, data, and material properties) or a team operations guide (detailing workflows, coding standards, and best practices). Majority of the handbooks cover a specific technology or field of engineering.
Engineering instrumentation – It is the use of devices and systems to measure, monitor, and control physical quantities like temperature, pressure, flow, and level. It integrates electrical, mechanical, and computer principles to automate processes, ensuring industrial systems operate safely, efficiently, and accurately.
Engineering instruments – These are devices used to measure, analyze, record, or control physical quantities (such as temperature, pressure, flow, and voltage). They are critical across mechanical, electrical, and civil disciplines to ensure safety, operational efficiency, and precise data in manufacturing and research.
Engineering judgement – It is the application of an engineer’s professional expertise, experience, and scientific knowledge to make informed, safe decisions. It is important when navigating ambiguous situations, conflicting data, or job-site conditions which fall outside the scope of standardized codes and manuals.
Engineering laboratory – It is a specialized facility equipped for conducting scientific experiments, testing materials, analyzing processes, and developing prototypes. Engineering laboratories are used in industry for research, design validation, and training, covering areas like robotics, structural testing, and manufacturing. Common examples include material testing, fluid mechanics, and electronics laboratories.
Engineering method – It is a systematic approach used to reach the desired solution to a problem. There are six steps (or phases) namely idea, concept, planning, design, development, and launch from problem definition to desired result. Engineering method supports an engineer or project team in reaching the desired solution to a problem, which has been specified by customers, sponsors, or stakeholders who perceive value in resolving the problem.
Engineering model – It is a physical, mathematical, or virtual representation of a system used to test design, validate functionality, and ensure safety before full-scale production. It serves as an iterative prototype to identify and resolve flaws early in the development life-cycle.
Engineering office – It is a coordinated work-space and organization entity where engineering teams develop project designs, construction drawings, and specifications. It bridges the gap between conceptual design and physical execution by managing budgets, technical compliance, and inter-disciplinary collaboration.
Engineering organization – It refers to the structural arrangement of people, processes, and resources dedicated to designing, developing, and deploying engineering solutions. It can denote an internal organizational department (e.g., a tech team) or an external professional association which sets industry standards and supports the profession.
Engineering normal strain (e) – It is the deformation per unit length, calculated as the change in length (dL or ‘L – Lo’ where ‘L’ is the final length) divided by the original, undeformed gauge length (Lo). It is a dimensionless measure of deformation under axial load, positive for tension (elongation) and negative for compression (shortening).
Engineering phase – It is a structured stage in project development where a team applies scientific and mathematical principles to transform concepts into actionable, technical designs. It bridges the gap between initial planning and physical construction, minimizing risks and ensuring the final product meets functional and safety specifications. The engineering phase is typically broken down into three core, progressive sub-phases namely conceptual engineering (feasibility), basic engineering (front-end engineering design, FEED), and detailed engineering.
Engineering plastics – It is a general term covering all plastics, with or without fillers or reinforcements, which have mechanical, chemical, and thermal properties suitable for use as construction materials, machine components, and chemical processing equipment components. Engineering plastics include acrylonitrile-butadiene-styrene, acetal, acrylic, fluorocarbon, nylon, phenoxy, polybutylene, polyaryl ether, polycarbonate, polyether (chlorinated), polyether sulfone, polyphenylene oxide, polysulfone, polyimide, rigid polyvinyl chloride, polyphenylene sulfide, thermoplastic urethane elastomers, and several other reinforced plastics.
Engineering, procurement, and construction (EPC) contract – It is a, frequently turnkey (lump-sum) project delivery model where a single contractor manages all aspects of a project, from detailed engineering design and material procurement to construction, commissioning, and handover to the owner.
Engineering professional – Engineering professional is a licensed or academically qualified expert who applies scientific and mathematical principles to design, develop, and optimize technical solutions. These professionals bridge the gap between theoretical research and practical application, ensuring that structures, software, and manufacturing processes are functional, safe, and cost-effective.
Engineering property – It is a quantifiable characteristic of a material or system which determines how it behaves under specific physical, chemical, or mechanical conditions. These measurable traits, such as strength, conductivity, and density, are necessary for design calculations, material selection, and structural safety. These characteristics are typically divided into several key categories to guide engineering design.
Engineering research – It is a structured investigation which applies scientific and mathematical principles to develop new technologies, optimize existing systems, or solve practical, real-world problems. It serves as the bridge between pure scientific theory and functional, marketable applications.
Engineering rock mechanics – It is the theoretical and applied science of the mechanical behaviour of rock and rock masses. It is the study of the response of rock to engineering-induced disturbances, incorporating principles from physical, mathematical, and geological sciences along with civil, petroleum, and mining engineering. It focuses on site-specific rock properties, utilizing laboratory tests and in-situ measurements to understand rock behaviour under various conditions. It applies solid mechanics and geology to design structures built in or on rock, such as tunnels, dams, and mine shafts, by predicting how rock responds to human-induced and natural forces.
Engineering scaffold – It is a temporary framework or a 3D architectural platform designed to provide physical and structural support. In construction, a scaffold is a temporary, elevated platform used to support workers, tools, and materials while building, repairing, or cleaning. It ensures safe access to heights and is typically constructed from prefabricated metal tubes (like steel or aluminum), couplers, and wooden or metal planks.
Engineering services – These services include construction and construction modification, removal and installation, and rearrangement of facilities.
Engineering specifications – These specifications are detailed documents which stipulate specific requirements for engineering, design, fabrication, and construction projects, guiding different stakeholders in ensuring that all components meet necessary standards and performance criteria.
Engineering staff – It normally refers to the organizational team of technical professionals responsible for researching, designing, and developing products or systems. In several organizations, a staff engineer is a specific, high-level technical leadership role for senior experts who guide organization-wide technology strategies without having direct management duties.
Engineering steel chains – These chains have been developed for greater strength, speed, shock resistance, and for better dimensional control. They operate dependably in the most demanding conditions. Several different types of engineering steel chains are used in a wide variety of applications. Most engineering steel chains are used in conveyors, bucket elevators, and tension linkages. Only a few are used in drives. The main design considerations for these chains are tensile loads, several types of wear, lubrication, and environment. The main design considerations for an engineering steel chain to be used on a drive include the various tensile loads, certain types of wear, roller and bushing impact, and galling.
Engineering strain (e) – It is a term sometimes used for average linear strain or conventional strain in order to differentiate it from true strain. In tension testing it is calculated by dividing the change in the gauge length by the original gauge length.
Engineering strain rate (e’) – It is the time rate of change of engineering strain, representing how fast a material deforms relative to its original dimensions. It is defined as the velocity of deformation divided by the original gauge length (Lo), normally expressed in units of reciprocal seconds.
Engineering strategy – It is a tailored plan which aligns an engineering team’s technical decisions, architecture, and processes with overarching organizational objectives. It answers how a team executes work, manages technical debt, and builds infrastructure to support the organizational long-term vision.
Engineering stress (s) – It is a term sometimes used for conventional stress in order to differentiate it from true stress. In tension testing, it is calculated by dividing the breaking load applied to the sample by the original cross-sectional area of the sample.
Engineering stress-strain curve – In the conventional engineering tensile test, an engineering stress-strain curve is constructed from the load-elongation measurements made on the test sample. The engineering stress (s) used in this stress-strain curve is the average longitudinal stress in the tensile sample which is got by dividing the load by the original area of the cross section of the sample. The strain (e) used for the engineering stress-strain curve is the average linear strain, which is got by dividing the elongation of the gauge length of the sample by its original length.
Engineering structures – These are constructed systems which are designed and analyzed based on fundamental principles, incorporating different modelling techniques for effective performance and stability. These structures are required to withstand loads or contain pressure, whilst satisfying specified performance targets. Several materials and joining processes are available to fabricate engineering structures.
Engineering students – They are individuals enrolled in engineering programmes who engage in hands-on experiences to understand theoretical concepts, collaborate on projects, and develop skills necessary for professional teamwork across different engineering disciplines.
Engineering system design – It is the process of defining the architecture, components, modules, interfaces, and data flow for a system to satisfy specified needs. It translates abstract concepts and operational needs into a concrete, implementable technical blueprint. The engineering system design process is typically broken down into two main phases namely high-level design (HLD) and low-level design (LLD) and is guided by several key principles.
Engineering, systems – System engineering is an interdisciplinary field of engineering and engineering management which focuses on how to design, integrate, and manage complex systems over their life cycles. At its core, systems engineering utilizes systems thinking principles to organize the systems engineering body of knowledge.
Engineering team – It is a collaborative group comprised of participants from different engineering and non-engineering disciplines, who contribute their expertise to support system design, implementation, and verification throughout the system life cycle. This team frequently includes roles such as systems engineering managers, requirements analysts, architecture developers, systems analysts, and integration and test members to address complex project needs.
Engineering theory – It is a systematic framework of scientific and mathematical principles used by engineers to design, analyze, and predict the behaviour of structures, systems, and processes. Unlike pure science, which seeks to understand why the universe works, engineering theory focuses on how to apply that knowledge to solve practical, real-world problems safely and economically. Understanding engineering theory frequently needs exploring several core dimensions.
Engineering thermodynamics – It consists of the fundamental principles governing the conversion, transfer, and utilization of energy in different forms, including heat, work, and electricity, necessary for designing and optimizing energy systems.
Engineering tolerance – It is the allowable deviation from a base (nominal) measurement. It ensures that parts function properly, fit together in assemblies, and remain interchangeable, even when inherent manufacturing inaccuracies occur. Tighter tolerances increase production costs, so engineers only specify them when strictly necessary. Engineering tolerances refer to the allowable variability in the dimensions of components produced through manufacturing processes, which ensures that assembled parts function reliably despite slight differences in size. This concept encompasses the specification of acceptable ranges for both individual components and processes to maintain performance standards.
Engineering tool – It is a method, instrument, or software used by engineers to design, simulate, analyze, or build systems. These tools apply scientific, mathematical, and technical knowledge to solve complex problems and are categorized mainly into physical instruments, computational software, and graphical / analytical methodologies.
Engineering units – These are standardized, conventional measurements, such as meters, kilograms, seconds, or mega-pascals, used to quantify physical properties in technical fields. They convert raw sensor data (e.g., voltage) into meaningful physical values (e.g., temperature or pressure) and are divided into International System of Units (metric) and Imperial / English systems.
Engineering view – It is a technical representation used in engineering and design which illustrates a three-dimensional physical object onto a two-dimensional sheet or digital screen. It provides precise perspectives needed for manufacturing, assembly, and analysis. These drawings use standardized symbols to eliminate personal interpretation. The most informative perspective (normally the functioning or manufacturing orientation) serves as the base.
Engineer of record – Engineer of record is the licensed professional engineer responsible for the design, preparation, and final sealing of engineering plans, calculations, and specifications for a project. They assume ultimate legal and professional accountability for ensuring the design meets all applicable safety codes and regulations.
Engine exhaust gas temperature – It is the measurement of the hot gases exiting the cylinders or turbine of an engine. It serves as an important diagnostic tool to evaluate combustion efficiency, ensure safe operational limits, and monitor overall engine health.
Engine failure – It occurs when a machine’s engine unexpectedly stops functioning properly or completely ceases to produce power. This can be caused by mechanical wear, fluid loss, electrical faults, or parts disintegrating. It can result in a complete shutdown or a partial loss of thrust. It is a heavy wheel mounted on the crankshaft. It stores the excess energy delivered by the engine during power stroke and supplies the energy needed during other strokes. Thus it keeps the fluctuations in the crankshaft speed within desired limits.
Engine flywheel – It is a heavy wheel mounted on the crankshaft. It stores the excess energy delivered by the engine during power stroke and supplies the energy needed during other strokes. Hence, it keeps the fluctuations in the crankshaft speed within desired limits.
Engine knock – It is an abnormal working state of an engine characterized by unusual sounds and vibrations, which can weaken the engine’s power output, increase temperature and fuel consumption, and potentially cause damage.
Engine management system – It is a mixed-signal embedded system which interacts with a spark ignition (SI) engine through different sensors and actuators, incorporating control algorithms for functions such as air-to-fuel ratio control and ignition control to optimize engine performance, fuel consumption, and emissions.
Engine mountings – These are the components which secure an engine to a vehicle’s frame or chassis. Mainly made of metal and rubber, they absorb engine vibrations and harsh shocks, ensuring a smooth, quiet, and stable ride for the passengers.
Engine oil – It is an oil which is used to lubricate an internal combustion engine.
Engine operating point – It is the specific combination of rotational speed and load (or torque) at which an engine operates at any given moment. It is the main metric used to evaluate fuel efficiency, emissions, and overall powertrain performance.
Engine-out emissions – These emissions refer to the pollutants released from an engine after combustion, which include nitrogen oxides (NOx), carbon mono-oxide (CO), and hydro-carbons (HC). These emissions are influenced by factors such as the fuel composition, initial temperature, and combustion quality, with variations affecting the formation of different pollutants.
Engine part – It refers to any individual physical component which makes up an engine. In internal combustion engines, these thousands of coordinated parts work together to convert the chemical energy of fuel into the mechanical motion needed to power a vehicle.
Engine performance – It is a parameter on which the acceptability of an engine is strongly dependent. The fuel properties, fuel injection pressure and timing, air–fuel mixture, quantity of injected fuel, fuel spray pattern etc. have noticeable effects on engine performance.
Engine piston – It is a cylindrical, sliding component which moves up and down inside an engine’s cylinder. Its main function is to serve as a movable wall for the combustion chamber, transforming the energy of expanding gases into mechanical power to drive the crankshaft.
Engine power – It is the rate at which an engine does work. In simpler terms, it measures how quickly an engine can generate energy to move or accelerate a vehicle. It is the main factor which determines a vehicle’s top speed and overall performance capability. Power relies on two main components namely torque (the twisting or pulling force) and engine speed.
Engine power cycle – It is a thermodynamic process which converts thermal energy (heat) into mechanical work. It uses a working fluid, such as air or steam, which undergoes repeated stages of compression, heating, expansion, and cooling, returning to its initial state to continuously produce power.
Engine room – It is the compartment in an industrial facility where the main propulsion machinery and heavy mechanical equipment are housed. It is basically the ‘heart’ or power-house of the plant.
Engine size – It is also called engine displacement. It is the total volume of air and fuel pushed through all of an engine’s cylinders in a single cycle. It is normally measured in litres or cubic centimeters.
Engine speed – It the rate at which an engine’s internal crank-shaft rotates. It is very frequently measured in revolutions per minute (rpm). For example, 3,500 rpm means the crankshaft completes 3,500 full rotations in a single minute.
Engine speed-load domain – It defines an engine’s operational space, mapped across two main variables namely engine speed (rotational velocity, typically revolutions per minute) and engine load (torque output or demand). It provides a comprehensive framework to understand and optimize engine performance, emissions, and fuel consumption.
Engine system – It is a mechanical system which combines hardware and software components to produce power through a working fluid medium, needing optimization, dynamic analysis, and control to achieve target performance while addressing factors such as gas pressures, temperatures, and flow rates.
Engine test cell – It is a specialized, controlled facility used to house and evaluate internal combustion or jet engines. It is designed to safely simulate real-world operating conditions, such as extreme temperatures, stress, and fluid flows, while precisely measuring performance metrics like torque, thrust, and emissions.
Engine thermal efficiency – It is the ratio of useful mechanical work output to the total chemical energy input from the fuel. It measures how effectively an engine converts fuel into power, with the remaining energy typically lost as heat and friction.
Engine torque – It is the rotational or twisting force produced by an engine’s crank-shaft. It represents the engine’s raw pulling power and its ability to overcome resistance, accelerate a vehicle from a standstill, or tow heavy loads.
Engine, traction – A traction engine is a self-propelled steam engine designed for mobility, which incorporates a horizontal locomotive-type boiler and utilizes rotary motion of the crankshaft transmitted to the wheels, allowing it to function as a prime mover for different industrial applications.
Engine volumetric efficiency – It is the ratio of the actual volume of air an engine’s cylinder takes in during the intake stroke to the cylinder’s theoretical displacement volume. It measures the engine’s ‘breathing capacity’. A higher percentage means the cylinder is filled more effectively, which translates to higher torque and power.
Engler viscosity – It is a commercial measure of viscosity expressed as the ratio between the time in seconds needed for 200 cubic centimeters of a fluid to flow through the orifice of an Engler viscometer at a given temperature under specified conditions and the time needed for 200 cubic centimeters of distilled water at 20 deg C to flow through the orifice under the same conditions. It is desired that standard viscosity units are used.
Engraved pattern – It is a specific design, texture, or groove permanently etched or carved into a physical surface. It is achieved through subtractive manufacturing methods like CNC (computer numerical control) milling, laser ablation, or chemical etching. These patterns serve critical functional, structural, or aesthetic purposes.
Engraving brass – It is the brass formulated to be best suited for engraving.
Engulfment – It normally describes a process where a fluid, substance, or interface completely surrounds, submerges, or swallows another material or object. In safety and occupational engineering (HSE), engulfment is defined as the surrounding or effective capture of a person by a liquid or finely divided (flowable) solid substance. In solidification processes, particle engulfment occurs when a solid-liquid interface (like a freezing metal) overtakes an impurity or secondary particle rather than pushing it away. In reactor design, the engulfment model (E-model) is a mathematical framework used to describe micro-mixing inside fluid reactors.
Enhanced adhesion – It describes the intentional strengthening of inter-molecular, mechanical, or chemical bonds at the interface of two dissimilar materials. It utilizes surface treatments, nano-materials, or geometric structuring to increase surface energy, maximize contact area, and prevent delamination.
Enhanced coal bed methane – It is a technique which injects gases like carbon di-oxide (CO2), or nitrogen (N2) into unmineable coal seams. The injected gases displace trapped methane (CH4), boosting recovery rates and allowing the coalbed to permanently sequester carbon di-oxide.
Enhanced coal bed methane recovery – It is a process which injects gases (typically carbon di-oxide (CO2), or nitrogen (N2) into deep, unmineable coal seams to displace and extract trapped methane (CH4). It serves dual purposes such as maximizing natural gas recovery while permanently storing greenhouse gases underground.
Enhanced data – It is the process of improving existing datasets by cleaning, validating, and adding new information to make data more complete, accurate, and actionable. It involves structuring data for deeper insights.
Enhanced diffusion – It is frequently called radiation-enhanced diffusion. It refers to the accelerated movement of atoms within a solid or material caused by external stimulation, such as radiation damage or mechanical deformation, which drastically lowers the activation energy required for atomic jumps.
Enhanced flooded batteries – These are a type of flooded lead-acid battery designed for micro-hybrid applications, characterized by features such as increased positive paste density, the use of fibre shims to reduce shedding, higher plate compression, special carbon additives in the negative material, and improved plate designs for better current distribution, all of which improve performance and cycle life under high-rate partial state of charge (HRPSoC) conditions.
Enhanced gas recovery – It is a tertiary engineering process used to extract trapped natural gas from depleted reservoirs. It involves injecting fluids, such as nitrogen, flue gas, or carbon di-oxide, into a reservoir to re-pressurize the field, displace the remaining gas, and improve extraction efficiency.
Enhanced geothermal systems – These are engineered, artificial reservoirs created to produce clean electricity from hot, dry rock (HDR) which lacks natural water or permeability. By injecting high-pressure water to create or expand fracture networks, enhanced geothermal system enables heat extraction in areas previously unsuitable for traditional geothermal energy.
Enhanced gravity separators – These are specialized metallurgical processing units designed to separate fine valuable minerals from gangue (waste) material by using centrifugal force, which is frequently dozens or hundreds of times higher than normal gravity (above 1G). Unlike traditional gravity separators (like spirals or shaking tables), enhanced gravity separator (EGS) technology bridges the gap between conventional gravity separation and froth flotation, making it highly efficient for processing fine and ultra-fine particles (roughly 1 millimeter down to a few micro-meters).
Enhanced image – It is a digital picture which has been modified to improve its visual quality, clarity, or appeal. It involves using digital editing or artificial intelligence to adjust elements like brightness, contrast, and sharpness, making specific features easier to perceive without altering the original content.
Enhanced insert – It refers to the optimization of embedded components (inserts) in manufacturing or thermal systems to improve mechanical strength, heat transfer, or flow dynamics.
Enhanced knowledge – It refers to an improved, deepened, or augmented state of understanding or information regarding a specific subject, skill, or field. It goes beyond merely increasing the quantity of information (which is simply ‘increased knowledge’), focusing instead on increasing the quality, depth, and application of that knowledge.
Enhanced model – It is a framework which calculates infiltration rates based on the pressure differences induced by stack and wind effects, incorporating factors such as leakage areas in building structures and interactions between these effects. It utilizes equations derived from Bernoulli’s principle and includes adjustments for specific building characteristics.
Enhanced oil recovery – It is also known as tertiary recovery. It is an advanced extraction process used to recover trapped crude oil from a reservoir which cannot be extracted using conventional primary and secondary methods. While traditional techniques recover 20 % to 40 % of a field’s oil, enhanced oil recovery (EOR) can boost total extraction up to 60 % or more.
Enhanced oil recovery technique – It is also called tertiary recovery technique. It is an advanced technique used to extract additional crude oil, frequently 30 % to 60 % more, from mature fields after primary and secondary methods are exhausted. Enhanced oil recovery (EOR) works by injecting substances (gas, heat, or chemicals) to alter the oil’s physical properties / chemical properties, reducing viscosity and improving flow, rather than just increasing pressure.
Enhanced process – it is the improvement, extension, or optimization of an existing workflow or model, utilizing data-driven insights to increase efficiency, quality, or speed. It involves analyzing actual operational data to identify bottlenecks and deviations, then modifying the process to achieve superior, more reliable results
Enhanced product – It is a modified or updated version of an existing product, designed to improve quality, performance, or value to better meet customer needs. It frequently includes extra features, improved functionality, or services, such as warranties, support, or superior design, which go beyond the core product to offer superior user experience.
Enhanced recovery methods – These methods refer to techniques used to recover more oil from reservoirs beyond natural production, typically classified into secondary and tertiary recovery methods. These methods include processes such as water injection, gas injection, thermal methods, and chemical injection, aimed at improving oil displacement and sweep efficiency.
Enhanced recovery projects – These projects refer to techniques aimed at increasing oil production from reservoirs, utilizing methods such as improved waterflooding and thermal recovery, which have shown promise in laboratory and pilot testing for technical and economic success. These projects are frequently supported by government funding to accelerate commercialization and increase oil output.
Enhanced reflectivity – It refers to the use of engineered surface treatments, such as multi-layer thin-film coatings or nano-structures, to artificially increase a material’s capacity to reflect incident electro-magnetic radiation. This technique is widely used in optics, and energy to control light absorption, manage heat, and boost device efficiency.
Enhanced resistance – It refers to the intentional optimization of a system, structure, or material to withstand external stressors (e.g., thermal, mechanical, electrical, or corrosive). It relies on specific, measurable material properties and physical phenomena to prevent failure, degradation, or energy loss.
Enhanced signal techniques – It refers to techniques which improve the clarity, discernibility, and quality of a physical or electrical signal against background interference. In hardware engineering, this is achieved by increasing the signal-to-noise ratio (SNR), sampling at higher bit-resolutions, or altering wavelengths and lenses for clearer optical output.
Enhanced strain – It refers to an additional or modified strain component incorporated into the standard displacement-gradient formulation in elasticity problems, allowing for improved accuracy in the analysis of material behavior under deformation.
Enhanced vision systems – These systems refer to imaging systems which utilize sensors, such as forward-looking infrared or millimeter-wave radar, to provide an enhanced image of the external scene, thereby improving situational awareness. The quality of enhanced vision systems (EVS) images is highly dependent on the types of sensors used.
Enhance fly ash – Fly ash enhances refers to the process by which fly ash, a byproduct of thermal power plants, is utilized to improve the properties of materials, such as increasing the fire resistance and mechanical strength of polymer composites and concrete. This is achieved through the incorporation of its components, such as silicon di-oxide and metal oxides, which contribute to superior performance characteristics.
Enhancement factor – It is a multiplier used to quantify how much a physical, chemical, or electrical process is improved, accelerated, or amplified by a specific intervention or mechanism.
Enhancement layer – It is a supplementary data or material component added to a foundational ‘base layer’ to increase its quality, resolution, performance, or value.
Enlargement of fillets – It refers to increasing the radius of the concave, rounded transition corner between two surfaces which meet at an angle. This design adjustment is mainly used to distribute stress over a larger area, reducing stress concentration, improving fatigue strength, and minimizing the risk of cracks or ‘hot tears’ during casting and forging processes.
Enhance production – It refers to methods used to increase oil extraction from a well, frequently through processes such as gas reinjection or enhanced oil recovery (EOR), which maintain reservoir pressure and improve production rates.
Enhancing mechanism – It involves refining the precise, functional description of a mechanical assembly to ensure it transmits forces and motions in a highly predictable, constrained manner. Optimizing this definition bridges the gap between conceptual design and robust physical execution.
En-masse conveying system – It is also called trough conveying system. It is based on a continuous conveyor using a drive mechanism. This is an endless chain of so-called flights or rather transverse flights. The entire system runs in a closed trough, which is where its name has come from. En-masse conveyors are the perfect solution for conveying virtually any free-flowing bulk material in both vertical and horizontal directions.
Enriched uranium – It is the uranium in which the percent composition of Uranium-235 has been increased from the natural level of around 0.7 % through the process of isotope-separation.
Enrichment – It is the process used to increase the abundance of fissile isotopes in an element, such as naturally-occurring uranium.
Ensemble average – It refers to the expected value of a property obtained statistically from a collection of representative phase points for all microstates in a macrosystem, calculated using their probabilities. It is expressed as a continuous function of the property and the probability density function over the ensemble of possible motions.
Enskog equation – It is a foundational kinetic theory model used to describe dense gases and liquids. It is the main extension of the classical Boltzmann transport equation, which is limited to dilute gases, accounting for the finite size of molecules and non-local, instantaneous collisions.
Ensuing analysis – It is the systematic examination of a system, component, or data which immediately follows a preceding event, action, or failure. It serves as a downstream diagnostic or optimization step to determine causes, inform mitigation strategies, or predict future behaviour based on baseline testing.
Enstatite – It is a common rock-forming silicate mineral belonging to the orthorhombic pyroxene group, characterized by the formula Mg2Si2O6 (magnesium silicate). It is typically found in igneous and metamorphic rocks, ranging in colour from white, grey, or green to brown.
Enstatite-ferrosilite solid solution series – It is a complete, continuous range of silicate minerals in the orthopyroxene group [formula (Mg,Fe)SiO3 or (Mg,Fe)2Si2O6), spanning from pure magnesium end-member enstatite (MgSiO3, En) to pure iron end-member ferrosilite (FeSiO3, Fs). These common rock-forming minerals are important components of igneous rocks, metamorphic rocks, and meteorites.
Entangled photons – These are pairs of photons whose quantum states are fundamentally inter-dependent. The measurement of one photon instantaneously determines the state of its partner, regardless of distance. Photon engineering involves actively designing the physical systems and optical properties which govern how these photon pairs are generated, shaped, and manipulated.
Entangled states – These are quantum systems of two or more particles whose properties are so deeply linked that the state of one cannot be described independently. Measuring one particle instantly determines the state of its paired companion, even across large distances.
Entanglement – It is a type of correlation between sub-systems which cannot be explained by classical random processes, representing a fundamental concept in quantum information theory and enabling the transmission of quantum information through channels which cannot be simulated by classical means.
Entanglement concentration – It refers to the critical polymer concentration necessary for the entanglement of polymer macro-molecular chains, beyond which stable nano-fibres can be formed instead of droplets during the electro-spinning process. It is defined as the threshold at which the polymer solution achieves sufficient chain entanglement to facilitate the development of continuous nano-fibres.
Enterprise – A company, business, firm, institution or organization designed to provide goods and / or services to the consumers. It can imply for-profit business, not-for-profit organizations, agencies, or self-employed individuals.
Enterprise asset mastery – It is an integrated methodology for overseeing the complete lifecycle of physical assets, designed to optimize utilization, improve cost efficiency, elevate quality standards, ensure health and safety, and safeguard environmental well-being.
Enterprise asset oversight – It is the holistic strategy for managing the entire lifespan of physical assets, integrating measures for optimized utilization, cost-effectiveness, heightened quality, and efficiency, along with safeguarding health, safety, and environmental standards.
Enterprise information technology – It refers to large-scale, robust hardware, software, and services designed to meet the complex data, security, and scalability needs of major organizations. These systems integrate disparate business processes, such as HR, finance, and manufacturing, into a unified, top-down, and highly secure infrastructure.
Enterprise integration – It is the strategic practice of connecting disparate IT (information technology) systems, applications, and databases to enable seamless data exchange, process automation, and interoperability across an organization.
Enterprise resource planning – It is a software system that helps organizations streamline their core operating processes such as finance, human resource, manufacturing, supply chain, marketing, and procurement etc. with a unified view of activity and provides a single source for information. At its most basic level, it helps to efficiently manage all these processes in an integrated system. It is frequently referred to as the system of record of the organization.
Enterprise risk – It is the broad spectrum of potential internal and external uncertainties, strategic, operational, financial, and compliance-related, which can affect an organization’s ability to achieve its objectives and create value. It encompasses holistic, organization-wide risk management rather than isolated, functional risk management.
Enterprise risk management – It is a comprehensive, structured framework for identifying, assessing, and mitigating risks across an entire organization. By integrating risk management into strategic planning and daily operations, enterprise risk management (ERM) enables organizations to minimize threats and capitalize on opportunities, hence preserving and creating value.
Enterprise system – It is a large-scale, integrated software package designed to support and automate core organizational processes, data, and workflows across an entire organization. These systems break down functional silos by sharing a central database, ensuring consistent information flow from manufacturing to human resources and finance.
Enthalpy – It is the sum of a thermodynamic system’s internal energy and the product of its pressure and volume. It is a state function in thermodynamics used in several measurements in chemical, biological, and physical systems at a constant external pressure, which is conveniently provided by the large ambient atmosphere.
Enthalpy change – It is the heat energy absorbed or released by a system during a process at constant pressure. It represents the total heat transfer involved in chemical reactions, phase transitions, or flow processes, and is defined as the difference between the final and initial enthalpy states.
Enthalpy drop – It is the decrease in the specific enthalpy (h) of a working fluid (like steam or gas) as it expands through a device. It represents the conversion of thermal energy into mechanical work or kinetic energy, and is calculated using the formula ‘delta h = hin – hout)’.
Enthalpy energy equation – It is the conservation equation which describes the total enthalpy within a flow field, accounting for changes in mass, momentum, and energy as functions of space and time. It incorporates terms related to heat transfer and viscous stresses, reflecting the dynamics of the flow in a compressible fluid context.
Enthalpy method – It is a numerical modeling technique used to simulate phase changes (like melting and solidification) in engineering. Instead of tracking a moving boundary between liquid and solid, it uses enthalpy (total heat content) as the main variable, allowing the energy equation to be solved continuously across the entire system.
Enthalpy of adsorption – It is the heat energy released or absorbed when molecules (adsorbate) adhere to a surface (adsorbent). It measures the binding strength between the molecules, typically expressed in kilo-joules per mol. A negative value indicates an exothermic process, which is the most common.
Enthalpy of fusion – Enthalpy of fusion of a substance, also known as (latent) heat of fusion, is the change in its enthalpy resulting from providing energy, typically heat, to a specific quantity of the substance to change its state from a solid to a liquid, at constant pressure. The enthalpy of fusion is the quantity of energy required to convert one mole of solid into liquid.
Enthalpy-porosity approach – It is a computational fluid dynamics (CFD) technique used to simulate melting and solidification processes without needing to track the exact physical boundary of the phase front. Instead, it treats the solid-liquid ‘mushy zone’ as a porous medium, dynamically updating state variables based on energy conservation.
Enthalpy values – These refer to the measurement of enthalpy, which is defined as the sum of internal energy and the product of pressure and volume, expressed relative to a reference state where the enthalpy is typically set to zero for convenience.
Entire life cycle – It refers to the comprehensive, phased journey of a system or product, from initial concept, design, and manufacturing through its operational use, and ultimately to its retirement, disposal, or recycling. This holistic approach is called life cycle engineering (LCE).
Entity – It is a distinct, identifiable object, concept, or component which exists independently and about which data is stored or processed. Entities can be tangible (a physical machine) or intangible (a software process, database record, or network node). They are defined by specific attributes and are fundamental to systems modelling, database design, and software architecture.
Entity work (W) – It is frequently paired with energy. It is the measure of energy transferred to or from an object by applying a force (F) over a distance (d). The basic mathematical definition, where force and displacement are parallel, is ‘W = F x d’. If the force acts at an angle (A) to the direction of motion, it is defined as ‘W = F x d cos A. Its unit is joules or Newton-meter.
Entomb – It is a method of decommissioning whereby the radioactive material is encased in a structurally long-lived material, such as concrete. The entombment structure is appropriately maintained and continued surveillance is carried out until the radioactivity decays to a level permitting decommissioning and ultimate unrestricted release of the property.
Entrained air – It refers to the air which is induced into a fire plume because of the buoyant force, which is necessary for fuel combustion and influences factors such as flame shape, burning rates, and soot formation.
Entrained concrete – It is a specialized mix containing billions of microscopic, evenly spaced air bubbles. Created intentionally using chemical admixtures, this air-void network improves workability and provides important internal expansion chambers which prevent cracking and structural failure during freezing and thawing cycles.
Entrained flow absorber (EFA) process – This process is installed at the end of the sinter plant process. It essentially consists of an entrained flow absorber and a bag-type filter. Using this equipment, from the sinter plant off-gas, dust, sulphur oxides, hydrochloric, hydrofluoric acids, dioxins and furans are captured. The absorber operates with hydrated lime (calcium hydroxide) and brown coal coke to absorb dioxins and furans. The optimum reaction conditions are reached by means of water sprayed into the reactor at high pressure and maintaining the temperature in the range of 80 deg C to 110 deg C. The injected water is evaporated and dust from the off-gas is collected in the bag-type filter. The sulphur content is lower than 50 milligrams per cubic metre at standard temperature and pressure, dust content is lower than 5 milligrams per cubic metre at standard temperature and pressure and furans / dioxins content are lower than 0.1 nano-grams per cubic metre at standard temperature and pressure.
Entrained flow gasifier – It is a reactor where finely pulverized feedstock (coal, biomass, or waste) and a gasifying agent (oxygen / steam) are injected together in a high-velocity, co-current stream. Operating at high temperatures and pressures, it yields high-quality, tar-free syngas through rapid mixing and heat transfer.
Entrained water – It refers to liquid droplets or moisture unintentionally captured and carried along by a high-velocity gas or vapour stream. It occurs in different disciplines, including chemical, mechanical, and nuclear engineering, frequently reducing system efficiency or causing contamination.
Entrainer – It is a third component added to a binary mixture in an azeotropic distillation process to influence the azeotropic system, facilitating the collection of pure products.
Entraining admixtures – These are admixtures which introduce a large numbers of uniform, stable, and closed tiny bubbles into concrete mixtures, improving workability, improving impermeability and frost resistance, while potentially reducing compressive strength.
Entraining velocity – It is the velocity of a liquid at which bubbles of gas are carried along in the stream.
Entrainment limit – It is the critical threshold where a high-velocity vapour flow shears and lifts liquid droplets from a liquid-gas interface (or wick structure) into the vapour stream. This phenomenon, also known as flooding, disrupts fluid circulation and causes system failure. It is a major performance factor in several engineering fields.
Entrainment ratio (w) – It is the ratio of the mass flow rate of a secondary (induced) fluid (m-secondary) to the mass flow rate of a primary (motive) fluid (m-primary). ‘w = m-secondary / m-primary’. Entrainment ratio is the ratio of entrained flow to driving flow, indicating how much fluid is drawn into a system relative to the driving fluid. For example, an entrainment ratio of 9 to 1 means that 9 litres per minute are entrained by 1 litre per minute of driving gas. It is a key performance indicator in fluid mechanics, used to evaluate systems that rely on one fluid to pull, pump, or mix with another.
Entrance burr – It is the burr formed on the surface at which the cutting tool or its teeth enters the work-piece.
Entrance zone – It refers to a transitional region where fluid, traffic, or physical environments move from external conditions into a constrained space.
Entrant cavity – It is very frequently referred to as a re-entrant cavity. It typically refers to two distinct applications, both of which describe a structure where boundaries or walls extend inward to shape energy or fluid flow.
Entrant jet – It is also called re-entrant jet. It is a reverse-flow phenomenon where a thin film of liquid travels backward beneath a vapour cavity. It occurs when localized pressure gradients push fluid upstream, cutting off the cavity and triggering unstable cloud cavitation.
Entropic elasticity – It is the property where a material’s elastic behaviour originates from changes in its molecular entropy (disorder) rather than internal energy. When deformed (e.g., stretching rubber), polymer chains straighten out, reducing their conformational entropy. The resulting restoring force drives the material to return to a higher-entropy, coiled state.
Entropy – It is the measure of a system’s thermal energy per unit temperature which is unavailable for doing useful work. Because work is obtained from ordered molecular motion, the quantity of entropy is also a measure of the molecular disorder, or randomness, of a system. It is a scientific concept which is normally associated with a state of disorder, randomness, or uncertainty. The term and the concept are used in diverse fields. Entropy is central to the second law of thermodynamics, which states that the entropy of an isolated system left to spontaneous evolution cannot decrease with time. As a result, isolated systems evolve toward thermodynamic equilibrium, where the entropy is highest. A consequence of the second law of thermodynamics is that certain processes are irreversible.
Entropy balance – It is an application of the second law of thermodynamics used to quantify irreversibilities and track entropy changes within a system. It states that the change in a system’s entropy equals the net entropy transferred across its boundaries plus the entropy internally generated by irreversibilities.
Entropy balance equation – It is a mathematical expression of the second law of thermodynamics. It states that the change in entropy of a system equals the net entropy transferred into or out of the system, plus the entropy generated within the system because of the irreversibilities.
Entropy change – It is a thermodynamic property measuring the change in a system’s molecular disorder or the unavailability of its thermal energy to perform useful work. As a state function, it depends solely on the initial and final states of a process. For any process, entropy change is defined as the integral of heat transfer divided by temperature.
Entropy creation – It is also called entropy generation. It is the of entropy produced within a system during an irreversible process, caused by inefficiencies like friction, turbulence, or unrestrained expansion. It measures energy degradation, i.e., the loss of useful energy which becomes unavailable to do work.
Entropy encoder – It is a lossless data compression technique which reduces the average number of bits needed to represent data by assigning shorter codes to frequently occurring symbols and longer codes to rare ones. It operates on the information theory principle of entropy.
Entropy fluctuation – It refers to the microscopic or macroscopic deviations of a system’s actual entropy from its equilibrium value. These variations occur in response to thermal noise, fluid turbulence, or changes in probability states, driving unpredictable shifts in energy, density, and temperature.
Entropy generation – It measures the quantity of entropy produced within a system because of the real-world irreversibilities like friction, turbulence, and heat transfer across a finite temperature difference. It indicates energy degradation and system inefficiency.
Entropy generation rate – It is a quantitative measure of the irreversibilities, such as friction, unrestricted expansion, and unresisted heat transfer, occurring within a thermodynamic system. It gauges how much energy is degraded into unusable forms, always acts as a positive value, and is calculated using the second law of thermodynamics.
Entropy inequality – It is a thermodynamic principle stating which the total change in entropy of a system, plus its surroundings, is always to be higher than or equal to zero for any spontaneous or real process.
Entropy measurement – It refers to the quantification of uncertainty or disorder within a signal, employing different methods such as Shannon’s entropy and log energy entropy to characterize the signal’s information content.
Entropy method – It is the most representative objective weighting tool. This method determines the relative importance of the attributes and how they are related to the evaluation or final result. That is, the entropy shows how a criterion reflects the information system and its uncertainty.
Entropy production – It quantifies the quantity of irreversibility, energy dissipation, and lost work created during a thermodynamic process. Since all real, practical processes involve friction, unrestrained expansion, or heat transfer across a finite temperature difference, they always create entropy, which reduces system efficiency.
Entropy production rate – It is the measure of entropy generated within a system over time because of the irreversible processes, such as friction, heat transfer across a finite temperature gradient, or chemical reactions. By the second law of thermodynamics, it is always to be higher than or equal to zero.
Entropy rate balance – It is the application of the second law of thermodynamics. It establishes that the rate of change of entropy within a system equals the net rate of entropy transferred across its boundaries plus the rate of entropy internally generated because of the irreversibilities (like friction).
Entropy transfer – It is the transport of thermodynamic disorder or unavailability of energy across a system boundary. In thermodynamics, it is driven by two mechanisms namely heat transfer and mass flow.
Entropy transport – It is the transfer of entropy associated with mass crossing a system boundary, where each mass element carries a specific entropy which contributes to the overall entropy change in the system. The net mass flow entropy transport rate accounts for the sum of entropy contributions from all inlet and outlet streams.
Entry guide – It is a mechanism that precisely aligns and guides the material (like metal) as it enters the set of rollers. It ensures the material is correctly positioned and fed into the mill for consistent forming.
Entry operation – It refers to the initial phase of a project’s life cycle or a routine action needed to initiate a mechanical or chemical process. It specifically defines when a system is fully tested and ready for production, or when raw materials and fluids are mechanically fed into a system.
Entry velocity – It refers to the speed and direction at which a fluid, object, or material enters a specific system, boundary, or medium.
Envelope design – It typically refers to the building envelope, the physical barrier separating a building’s conditioned interior from the outside environment. It optimizes structural integrity, energy efficiency, and occupant comfort by controlling heat, air, and moisture transfer.
Envelope detection – It is a signal processing technique used to extract the low-frequency envelope or boundary which outlines a higher-frequency, amplitude-modulated (AM) signal. It is widely used in radio demodulation (amplitude-modulated receivers), sonar, radar, and mechanical fault diagnosis.
Envelope detector – It is an electronic circuit which takes a high-frequency modulated signal as input and outputs a wave-form which traces the peaks of the original signal. It is mainly used to recover the original message (base-band) signal from an amplitude-modulated (AM) wave-form.
Envelope equation – It defines the mathematical boundary or limit of a family of varying curves, wave signals, or system performance parameters. It outlines the extreme limits of a dynamic system, identifying maximums, minimums, or allowable operational spaces.
Envelope function – It is a smooth curve which outlines the extremes (peaks and troughs) of a rapidly varying oscillatory signal. It generalizes the concept of a constant amplitude to an instantaneous or time-varying amplitude.
Environment – It is the complex of physical, chemical, and biotic factors (climate, soil, and living things) which act upon metal and ultimately affect the corrosion rate.
Environmental acceptable hydraulic fluids – These fluids are basically used in the application where there is a risk of leakage or spills into the environment, which can cause some damage to the environment. These fluids are not harmful to the aquatic creatures and they are bio-degradable. These fluids are used in forestry, lawn equipment, off-shore drilling, dams and maritime industries. The ISO have classified these fluids as HETG (based on natural vegetable oils), HEES (based on synthetic esters), HEPG (poly-glycol fluids) and HEPR (polyalphaolefin types).
Environmental acoustics – It is the branch of engineering and applied physics which focuses on assessing, predicting, and controlling outdoor sound. It evaluates how sound propagates through the environment, interacting with terrain, atmospheric conditions, and barriers, and engineers solutions to mitigate noise pollution from transportation, industrial, and construction sources.
Environmental action – It is a planned, measurable measure designed to minimize, mitigate, or eliminate negative environmental impacts caused by industrial, operational, or production processes. It is the actionable implementation phase of an environmental management system (EMS), putting sustainable engineering principles into practice.
Environmental advantages – These refer to the beneficial impacts of utilizing natural resources, such as jute, which include high biomass production, carbon di-oxide absorption, and low reliance on chemical fertilizers, leading to reduced environmental pollution and improved ecological sustainability.
Environmental agenda – It is the organizational policy-driven plan for sustainability. It normally focus on the environmental issues, such as climate change and carbon di-oxide emissions.
Environmental agent – It is a physical, chemical, or biological external factor which interacts with a person, organism, or material. Exposure to these agents can considerably impact health, cause illnesses (such as cancer), or induce material degradation.
Environmental aspect – It is an element of an organization’s activities, products, or services which interacts or can interact with the environment. In short, an environmental aspect is the cause, an action or input, which leads to an environmental change. Understanding the distinction between an aspect and an impact is fundamental to environmental management, particularly under standards like International Organization for Standardization standard ISO 14001.
Environmental assessment – It is a process to identify, predict and evaluate the potential environmental effects of a proposed project. This process happens before decisions about a proposed project are made.
Environmental assessment method – It is a systematic procedure or framework used to evaluate, predict, and mitigate the potential environmental, social, and economic impacts of proposed projects before they are approved or carried out.
Environmental assisted cracking – It is the premature brittle failure of a material resulting from the combined, simultaneous effects of a corrosive environment and tensile stress. It threatens metals, alloys, and plastics, causing them to fracture at stress levels far below their normal mechanical capacity.
Environmental audit – It is a methodical examination involving analyses, tests, and confirmations to verify whether the emissions, discharges and waste management of the industrial plant comply with statutory requirements, internal norms and accepted practices. During the environmental audit, procedures and practices of the plant are also examined. Environmental audits are normally voluntary in nature and they are not the requirement which is imposed by the regulating agencies.
Environmental awareness – It is the understanding of the natural world, the impact of human behaviour on ecosystems, and the importance of protecting the environment. It bridges the gap between ecological knowledge and actionable, sustainable habits to preserve the planet for current and future generations.
Environmental barriers – These are obstacles, either natural or human-made, which make it difficult for people, especially those with disabilities, to access, use, or navigate the environment. Environmental barriers are normally seen as negative features of the environment. These barriers can limit participation in daily life, create social isolation, and affect overall well-being.
Environmental benefit – It is a positive, measurable impact which an action, policy, or practice has on the natural environment, ecosystems, or public health. These gains are typically generated by reducing pollution, conserving resources, or restoring natural habitats.
Environmental certification – It is a form of environmental regulation and development where an organization can voluntarily choose to comply with predefined processes or objectives set forth by the certification service. Majority of the certification services have a logo (normally known as an ecolabel) which can be applied to products certified under their standards. This is seen as a form of corporate social responsibility allowing organizations to address their obligation to minimize the harmful impacts to the environment by voluntarily following a set of externally set and measured objectives.
Environmental chamber – It is an engineered, sealed enclosure used to simulate specific environmental conditions, such as extreme temperature, humidity, altitude, or pressure, to test the performance, reliability, and durability of products, materials, and components. These chambers provide controlled, repeatable, and frequently accelerated, testing to ensure products meet quality and regulatory standards.
Environmental chemical engineering – It is the application of chemical engineering principles to minimize pollution, maximize resource efficiency, and develop sustainable industrial processes. It focuses on scaling up scientific and biological solutions to solve ecological challenges, ranging from wastewater treatment to clean energy generation.
Environmental clearance – it is the clearance for the project from the environment regulatory authorities. It is normally given after the project authorities have made and submitted an acceptable report for the environmental impact assessment and environmental management plan.
Environmental clearance (EC) process – The environmental clearance process has several steps which are required to be followed. These steps are (i) screening, (ii) scoping and consideration of alternatives, (iii) baseline data collection, (iv) impact prediction, (v) assessment of alternatives, description of mitigation measures and environmental impact statement, (vi) public hearing, (vii) environment management plan, (viii) decision making, (ix) monitoring of the clearance conditions.
Environmental code – It is a consolidated, comprehensive set of regulatory or procedural rules designed to protect the environment, regulate natural resources, and ensure sustainable development. It unifies disparate environmental laws, policies, and management practices into a single, cohesive framework.
Environmental compensation – It is the measures taken to address adverse effects caused by a project, particularly those impacting ecosystems and communities, ensuring that the compensation effectively mitigates the negative impacts while maintaining ecological functions. It involves careful assessment and follow-up to prevent further conflicts and to ensure that the compensated ecosystems resemble their original state.
Environmental concerns – These are challenges and issues resulting from human activities that negatively impact the Earth’s natural environment and ecosystems. They represent people’s collective awareness and worry about environmental degradation, and encompass the active measures taken by society, government, and individuals to protect natural resources. Environmental concerns refer to a general concept consisting of a series of broad attitudes towards land, air, and water pollution, which influence individuals’ behaviours related to the environment. These concerns are positively associated with environmentally friendly behaviours and attitudes towards energy conservation.
Environmental conditions – These conditions refer to the surrounding physical, chemical, or biological factors (e.g., climate, air / water quality, contamination) influencing a system, structure, or site. They include static conditions (design constraints) and dynamic conditions (operational changes) which impact performance, safety, and compliance with regulations.
Environmental control system – It is a critical technology used to automate, regulate, and maintain stable indoor conditions, including temperature, humidity, airflow, and air quality. The specific function of an environmental control system (ECS) depends heavily on its operational context.
Environmental cost – It refers to the direct and indirect expenses incurred in relation to the assessment, prevention, mitigation, reclamation, and compensation of environmental impacts caused by human activities. These costs are often not included in conventional economic measure.
Environmental cracking – It is the brittle fracture of a normally ductile material in which the corrosive effect of the environment is a causative factor. Environmental racking is a general term which includes corrosion fatigue, high temperature hydrogen attack, hydrogen blistering, hydrogen embrittlement, liquid metal embrittlement, solid metal embrittlement, stress-corrosion cracking, and sulphide stress cracking. Several other terms have been used in the past in connection with environmental cracking, but have now become obsolete. These terms are caustic embrittlement, delayed fracture, season cracking, static fatigue, stepwise cracking, sulphide corrosion cracking, and sulphide stress-corrosion cracking.
Environmental damage – It is the adverse impact caused to the environment by human activities, such as industrialization and pollution, for which polluters can be held legally accountable. This damage can affect not only the local ecosystem but also neighbouring regions and the global environment.
Environmental degradation – It is the reduction of the capacity of the environment to meet social and ecological objectives and needs is known as environmental degradation. Degradation of the environment can alter the frequency and intensity of natural hazards and increase the vulnerability of communities. The types of human-induced degradation are varied and include land misuse, soil erosion and loss, desertification, wild land fires, loss of biodiversity, deforestation, mangrove destruction, land, water and air pollution, climate change, sea level rise and ozone depletion.
Environmental design – It is the process of creating spaces, structures, and products which harmonize with natural ecosystems and improve human well-being. It integrates principles from architecture, landscape design, urban planning, and behavioural psychology to minimize negative environmental impacts and improve ecological health.
Environmental dimension – It refers to the natural surroundings, ecosystems, and resources which influence or are impacted by human activities. It is a core pillar of sustainability—alongside social and economic dimensions, focusing on minimizing ecological footprints, promoting biodiversity, and ensuring that natural resources are preserved for future generations.
Environmental disturbance – It is a discrete event, force, or process, natural or human-caused, which disrupts an ecosystem’s structure, community composition, or resource availability. These events alter physical environments and frequently cause organism mortality, ultimately driving ecosystem dynamics, recovery, and bio-diversity.
Environmental durability – It refers to a material or product’s ability to resist deterioration and maintain its performance characteristics when exposed to harsh external conditions, such as extreme temperatures, moisture, UV (ultra-violet) light, and chemical exposure, over its intended service life.
Environmental emissions – These are the release of harmful gases, particles, or other pollutants into the atmosphere and broader environment. Mainly driven by human activities like fossil fuel combustion and industrial processes, they are a major cause of climate change and air pollution.
Environmental enforcement – It refers to the statutory and regulatory actions taken to ensure full compliance with environmental laws, halt activities which threaten public health, and penalize violators. It is the practical application of legal mandates designed to protect ecosystems, air, water, and soil.
Environmental engineering – It is a branch of engineering which applies scientific and mathematical principles to protect public health and the environment. It involves designing systems and technologies to control pollution, supply clean drinking water, manage waste, and promote sustainable development.
Environmental engineers – These engineers apply scientific and engineering principles to improve the environment, protect human health, and promote sustainability. They develop solutions to control pollution, ensure access to clean drinking water, manage solid and hazardous waste, and mitigate the impacts of climate change.
Environmental enhancement – It is the process of actively improving ecological quality and sustainability through regulations, conservation efforts, or design practices. It balances economic activity with ecological protection, aiming to reverse degradation and restore natural habitats.
Environmental ergonomics – It is the scientific study of how physical surroundings affect human health, comfort, and performance. It evaluates external factors like thermal conditions, lighting, noise, and vibration to optimize spaces for safety, well-being, and productivity.
Environmental evaluation – It is a systematic process which identifies, predicts, and assesses the potential environmental, social, and economic consequences of a proposed project, policy, or activity prior to decision-making. It is used to minimize negative ecological impacts and ensure sustainable development.
Environmental factors – These are the conditions in an ecosystem which affect living organisms, encompassing both physical and biological aspects. These factors can be broadly categorized into abiotic and biotic elements. Abiotic factors include non-living elements like temperature, light, water, soil, and air, while biotic factors involve living organisms and their interactions, such as competition, predation, and parasitism.
Environmental footprint – It is a measure of the impact human activities have on the environment. It quantifies the quantity of natural resources consumed and the waste generated by an individual, community, organization, or product in relation to the earth’s capacity to renew those resources.
Environmental footprint assessment – It is a multi-criteria analytical method used to measure the total impact of a human activity, organizational activities, or product on the environment. It evaluates resource consumption, waste generation, and pollution across an entire life cycle to help organizations and individuals improve sustainability.
Environment, health, and safety – It is a multi-disciplinary field which focuses on the protection of human health and the environment in different settings, including work-sites, communities, and public spaces. The main objectives of environment, health, and safety (EHS) are to identify and mitigate potential hazards, prevent accidents and promote a safe and healthy living and working environment.
Environmental impact – It is any change to the environment, whether adverse or beneficial, which results wholly or partially from human activities, products, or services. It encompasses a wide range of effects, including pollution, resource depletion, habitat destruction, and climate change.
Environmental impact analysis – It is a systematic process used to predict and evaluate the potential environmental, socio-economic, and human-health effects of a proposed infrastructure or development project before construction begins. Its main goal is to inform decision-making and minimize ecological harm.
Environmental impact assessment – It is a process which predicts the effects of proposed developments on the environment which informs decision-makers in relation to planning permissions, consents, licenses and other statutory approvals. The purpose of environmental impact assessment is to identify and evaluate the potential impacts (beneficial and adverse) of the planned project on the environmental system. It is a useful tool for decision making based on understanding of the environmental implications including social, cultural and aesthetic concerns which can be integrated with the analysis of the project costs and benefits. It is also a system-wide determination of the multiple impacts which an engineering product has on the environment.
Environmental impact assessment study – It is a written report, compiled prior to a plant approval decision, which examines the effects proposed plant is going to have on the natural surroundings.
Environmental impact factor – It is a quantitative metric used to measure, evaluate, and minimize the ecological damage caused by a product, process, or infrastructure project. It acts as a standardized index to track variables like energy use, emissions, waste generation, and resource depletion.
Environmental impact statement – It is a comprehensive organizational or technical document which identifies and evaluates the potential environmental, social, and economic consequences of a proposed infrastructure or development project. It serves as a vital decision-making tool which a project’s benefits with its adverse effects, while proposing measures to mitigate damages.
Environmental indicator – It consists of a measurement, statistic or value which provides a proximate gauge or evidence of the effects of environmental management programmes or of the state or condition of the environment.
Environmental input – It refers to external conditions (like temperature, vibration, or humidity) which act on a system, or the raw materials and energy used in a process. Environmental inputs also refer to changes in environmental conditions which affect the output of a measurement system, leading to potential measurement errors. These inputs can modify the system’s output and complicate the determination of the actual measured variable.
Environmentalist – Environmentalist is a person or activist who campaigns for the preservation, restoration, and improvement of the natural environment. In contrast, an environmental engineer is a technical professional who uses math, science, and engineering principles to design practical solutions for pollution control, waste management, and public health.
Environmental label – It is also called eco-label. It is an official or voluntary certification which communicates the ecological impacts and sustainability of a product or service. These labels rely on a strict, science-based approach to quantify a product’s environmental footprint across its entire life-cycle.
Environmental laws – These are laws which protect the environment. Environmental law is the collection of laws, regulations, agreements and common law which governs how humans interact with their environment.
Environmental load – It refers to the different types of forces such as winds, currents, and waves which act on offshore structures over time, including short-term events like wind gusts and wave slamming, as well as long-term phenomena like steady waves and tides. Environmental load also represents the total burden or pressure a human activity or production system places on the environment. This normally means the total volume of greenhouse gases, pollutants, and waste discharged into the air, water, and land, or the rate at which natural resources are depleted.
Environmental loading – It refers to the natural, external forces and pressures exerted by the surrounding environment on a structure throughout its lifespan. Unlike constant weight (dead load) or occupancy (live load), these dynamic forces, such as wind, waves, earthquakes, and snow, are variable and location-dependent.
Environmentally assisted cracking – It is also called environmentally induced cracking. It is the forms of corrosion which produce cracking of metals as a result of exposure to their environment. This cracking can take the form of relatively slow, stable crack extension or, as is frequently the case, unpredictable catastrophic fracture. It is the brittle fracture of a normally ductile material in which the corrosive effect of the environment is a causative factor. Environmental cracking is a general term which includes corrosion fatigue, high temperature hydrogen attack, hydrogen blistering, hydrogen embrittlement, liquid metal embrittlement, solid metal embrittlement, stress-corrosion cracking, and sulphide stress cracking. In general, these different phenomena show several similarities, as well as there are several differences encountered between these different forms of environmentally assisted cracking, and in fact, substantial differences are observed for behaviour of metals and alloys within a specific form of cracking.
Environmentally assisted embrittlement – It is the embrittlement because of the environment conditions. The forms of environmental embrittlement include acid embrittlement, caustic embrittlement, corrosion embrittlement, creep-rupture embrittlement, hydrogen embrittlement, liquid metal embrittlement, neutron embrittlement, solder embrittlement, solid metal embrittlement, and stress-corrosion cracking.
Environmentally assisted fracture – It is the premature failure of materials (metals, alloys, plastics) because of the synergistic interaction of tensile stress and a harmful, normally corrosive environment. It typically causes brittle, unexpected fractures in normally ductile materials when both static or cyclic stress and a specific medium (like water, gas, or acid) are present, frequently causing failure below design loads.
Environmentally conscious manufacturing – It is an approach within the broader concept of green manufacturing, aimed at minimizing negative environmental impacts and maximizing resource efficiency throughout the industrial production process.
Environmentally induced fracture – It is a failure mechanism where a material experiences premature, brittle-like fracture under the combined, synergistic action of tensile stress and a harmful environment. [This type of failure occurs at stress levels below the material’s normal yielding point (tensile strength), which does not typically cause failure in a neutral environment.
Environmentally sound technologies – These are technologies which have the potential for significantly improved environmental performance relative to other technologies. Environmentally sound technologies protect the environment, are less polluting, use resources in a sustainable manner, recycle more of their wastes and products, and handle all residual wastes in a more environmentally acceptable way than the technologies for which they are substitutes. These technologies are not just and individual technologies. They can also be defined as total systems which include know-how, procedures, goods services, and equipment, as well as organizational and managerial procedures for promoting environmental sustainability.
Environmentally sustainable transport – It refers to mobility systems designed to meet societal access needs while drastically reducing greenhouse gas emissions, ecological degradation, and resource depletion. The engineering approach relies on a systems framework to balance economic viability, social equity, and ecosystem health.
Environmental management – It is a systematic approach for incorporating energy and environmental goals and priorities (such as energy use and regulatory compliance) into the routine operations. While some sort of de-facto system is inherent to the organization which is to meet the requirements of energy and environment as part of its daily operations, it is normally accepted as a valuable step to formalize the approach by documenting it. Not only does documentation of the system ensure consistency over time and across employees, there is a growing body of evidence indicating that there is considerable value in defining a systematic approach to managing energy and environmental goals. Environmental management system is also a systematic approach of meeting the goal and objectives of the organization. The focus of the environmental management system is on the quality principles for improving the environment.
Environmental management plan – It describes how an action might impact on the natural environment in which it occurs and sets out clear commitments from the people taking the action on how those impacts are avoided, minimized and managed so that they are environmentally acceptable. It is needed for the formulation, implementation and monitoring of environmental protection measures during and after commissioning of the project. Environmental management plan is required to indicate the details of the various measures already incorporated in the project or are proposed to be taken including cost components. Cost of measures for environmental safeguards is to be treated as an integral component of the project cost.
Environmental management system – It is a structured framework which enables organizations to identify, manage, monitor, and continually improve their environmental impacts. It integrates sustainability, pollution prevention, and resource optimization into core operational processes, ensuring compliance with regulations like the International Organization for Standardization standard ISO 14001.
Environmental medium – It is a distinct physical component of the natural or built environment, primarily air, water, or land, which can contain, transport, or be impacted by pollutants. It is the fundamental component engineers monitor, sample, and treat to protect ecosystems and public health.
Environmental model – It is a tool extensively used to evaluate different design, planning, and policy options by linking with optimization algorithms to identify the most suitable decision options for achieving the best environmental outcomes within resource constraints.
Environmental movement – It is a social movement which aims to protect the natural world from harmful environmental practices in order to create sustainable living.
Environmental nano-materials – These are substances at the nano-scale (1 nano-meter to 100 nano-meters) designed or used to monitor, remediate, or prevent ecological issues. Engineered through nano-engineering, their unusually high surface-to-volume ratio creates unique reactivity, allowing them to effectively target and break down contaminants.
Environmental nano-technology – It is the application of nano-science to design, produce, and utilize materials sized between 1 nano-meter to 100 nano-meters for environmental protection and sustainability. It leverages the unique, size-dependent properties of nano-materials, such as incredibly high surface-area-to-volume ratios, to solve global ecological and pollution challenges.
Environmental outcome – It is the desired environmental end state defining the specific conditions or functions which are expected for the environment. An outcome is an event, occurrence, or condition which results from an activity or programme that has an actual effect on resources, the environment, or the region.
Environmental noise – It is unwanted or harmful outdoor sound created by human activities (such as transportation, industry, and construction) which interferes with daily life, causes annoyance, or negatively impacts human health. It excludes noise generated in the work-place.
Environmental parameters – These are the specific, measurable external factors (physical, chemical, or biological) which surround, influence, or interact with a system, or component. These parameters define the operational conditions and are crucial for design, testing, and regulatory compliance.
Environmental performance – It refers to the measurable results of an organization’s or product’s interaction with the natural ecosystem. It uses quantifiable metrics and data to assess, control, and minimize negative environmental impacts across the entire life cycle of a design, process, or facility.
Environmental permit – It is permit issued by the Environment agency to control the environmental impacts associated with, among other issues, discharges and waste. It is also known as environmental consent.
Environmental pressure – It refers to the physical and systemic strain placed on natural resources and ecosystems by human activities. It encompasses both the underlying driving forces (like population growth and economic policies) and the direct consequences (like industrial pollution, deforestation, and waste generation) which alter the state of the environment.
Environmental product declaration – It is a quantified environmental information document concerning the life cycle of products and services, allowing for comparisons between items which perform the same function. Environmental product declarations (EPDs) are based on independent verification of life cycle assessment (LCA) data and follow specific product category rules (PCR) for data collection and presentation.
Environmental properties – These refer to the characteristics of a material which dictate its behaviour, durability, and performance when exposed to external operating conditions. In the broader field of environmental engineering, the term describes the physical, chemical, and biological parameters used to evaluate ecosystems and pollution levels.
Environmental protection – It is the application of scientific and engineering principles to minimize the negative impacts of human and economic activity on the natural environment. It focuses on preventing pollution, managing resources sustainably, and restoring ecosystems to protect both human health and ecological balance.
Environmental protection requirements – These refer to the strict criteria which are to be met in the evaluation of hydropower projects, focusing on minimizing impacts on terrestrial and aquatic life, and ensuring the preservation of natural reserves and rare species. These requirements can complicate the approval process for such projects.
Environmental quality – It is a measure of the status of the environment, overall or in relation to a media (air, water, land) or the needs of its inhabitants, including humans.
Environmental reform – It is the process of redesigning industrial systems, infrastructure, and methodologies to minimize ecological impact and improve sustainability. It blends engineering principles with environmental science to curb pollution, optimize resource efficiency, and adapt to climate change.
Environmental regulation – It is any state intervention in the market in order to protect the environment, be it by general rules or individual action. The basic orientation of ER depends on how it perceives nature such as ‘fate’, a resource, an ‘environment’, or a bio-sphere.
Environmental report – It is a technical document assessing how a proposed infrastructure project or facility impacts the surrounding ecology. It evaluates pollution, risks, and compliance, and outlines actionable engineering designs to mitigate environmental degradation and protect human health.
Environmental resistance – It is the ability of materials, components, or structures to withstand degradation, damage, and functional failure caused by external operating conditions. It determines long-term durability and is an important design factor to prevent structural or material break-downs.
Environmental risk – It is the statistical probability of adverse effects or harm to human health and ecosystems, resulting from exposure to physical, chemical, or biological stressors. It is calculated using the formula ‘risk = probability of hazard x severity of consequence.
Environmental risk assessment – It is a systematic process which evaluates the likelihood and severity of adverse effects on ecosystems and human health caused by engineering projects, industrial operations, or pollutants. Engineers use environmental risk assessment (ERA) to proactively identify hazards, measure potential impacts, and design preventive or mitigative controls.
Environmental scanning electron microscope – It is a specialized type of scanning electron microscope which enables the collection of electron micrograph samples in a gaseous environment, allowing for imaging of wet or non-conductive samples without damage. It operates under controlled pressure, temperature, and humidity conditions, facilitating direct observation of condensed water droplets on materials at the micro-scale.
Environmental sensors – These are the devices used to detect physical changes in the environment, such as temperature, humidity, and air pollution. They play a crucial role in monitoring conditions which can impact health, including respiratory issues.
Environmental solution – It refers to the application of scientific and engineering principles to design, construct, and manage systems which mitigate pollution, protect public health, and ensure sustainable development. It balances human needs with ecological preservation.
Environmental state – It is a concept describing a government which has developed specialized administrative, regulatory, and financial institutions to minimize ecological degradation and provide environmental welfare. The term can also refer to the base-line physical or biological condition of an ecosystem.
Environmental stress cracking – It is a common cause of polymer failure where a plastic part fractures under tension well below its normal mechanical strength. This brittle-looking failure is caused by the simultaneous and synergistic exposure of the material to mechanical stress and a chemical agent.
Environmental stress crack resistance – It is a vital property needed in plastics for its longevity. It is one of the most common causes of unexpected brittle failure in thermo-plastic. It is a measure of the susceptibility of a plastic to crack or craze under the influence of certain chemicals, stresses, or other agents.
Environmental support – It in engineering refers to the planning, design, and continuous provision of critical environmental conditions (such as power, temperature, humidity control, and fire protection) which systems need to function, particularly during emergencies or contingencies. In a broader engineering context, this concept ensures that technology and infrastructure are maintained in a stable environment to prevent failure, even if the environment is in a ‘degraded state’.
Environmental sustainability – It refers to the responsible management of natural resources to fulfill current needs without compromising the ability of future generations to meet theirs. It aims to balance ecological, economic and social goals, such as reducing carbon emissions, promoting renewable energy and ensuring equitable resource access.
Environmental system audit – It is a systematic, documented, periodic, and objective evaluation of an organization’s operational, management, and compliance practices regarding the environment. It identifies environmental risks, ensures compliance with laws, and measures performance against standards, frequently focusing on International Organization for Standardization standard ISO 14001 or specific pollution control measures.
Environmental technology – It is defined as the application of technology to improve the environmental quality and reduce the negative impacts of human activities on ecosystems. It encompasses methods to identify and understand environmental threats, as well as processes aimed at minimizing environmental degradation.
Environmental temperature – It refers to the temperature of the surrounding environment, which is a critical factor influencing the quality and safety of product. Accurate measurement of environmental temperature is necessary for compliance with different product specifications and regulations.
Environmental test – It is a procedure which subjects a module or system to extreme conditions, such as temperature, shock, vibration, humidity, pressure, and corrosion, to verify its capability to operate within expected environments and to identify potential weaknesses or faults.
Environmental testing – It is the process of evaluating a product’s ability to withstand different environmental conditions, such as temperature, humidity, and mechanical shock, to ensure it meets specified operational and storage requirements. This testing is necessary for identifying design limitations and confirming product reliability under anticipated deployment conditions. Environmental testing validates that designs meet specifications (qualification) or that production units are defect-free (acceptance).
Environmental textile – It is a technical fabric designed for ecological protection and conservation. This refers to the systematic design and manufacturing of fabrics using sustainable production techniques, green chemistry, and bio-degradable or recycled materials to minimize ecological footprints and improve circular economies.
Environmental variables – These refer to the conditions of a chemical system, such as temperature, pressure, and the presence of gravitational, magnetic, or electric fields, which are necessary for fully describing its physical state and can influence its thermodynamic properties.
Environment-assisted cracking – It is the premature, frequently brittle failure of a normally ductile material caused by the simultaneous combination of a susceptible material, tensile stress, and a specific corrosive environment. Environment-assisted cracking (EAC) occurs because of the adverse effects of the environment, predominantly from corrosive environments.
Environment-friendly lubricants – These are frequently referred to as environmentally acceptable lubricants (EALs) or bio-lubricants. These are oils and greases designed to minimize harm to ecosystems. They are defined by three key characteristics namely high biodegradability, minimal toxicity, and a lack of bio-accumulation.
Environment impact monitoring – It consists of the systematic observation of the state of the environment and of the factors influencing it. Its main purposes are to forecast changes to the state of the environment and to provide initial data for planning documents, programmes and projects. The procedure of environmental monitoring is established by law.
Environment parameters – These are measurable factors in a surrounding environment, including temperature, humidity, and brightness, which can be sensed to facilitate effective control and improve conditions, particularly in long-term care settings.
Environment plan drawing – Some projects are built around rivers or streams. In that case, the environmental plan drawing provides insights into how erosion and sedimentation is to be managed. These drawings also talk about plant effluent removal procedures and chemical disposal mechanisms. Moreover, it also has the procedures and plans to reduce the harmful effects.
Environment protection – It refers to the practices and policies aimed at safeguarding the natural environment from degradation and pollution. It is the safeguarding of the environment from negative impacts arising from economic activities, plans, or the use of natural resources. It is the systematic application of science and technology to prevent pollution, manage waste, and conserve natural resources, mitigating negative impacts from human activities on ecosystems. It focuses on sustainable design, water / air purification, and environmental remediation to protect public health and ecological balance.
Environment state – It is the complete, comprehensive set of information which describes the condition, properties, and configuration of a surrounding world or system at a given point in time. It encompasses all variables, dynamics, and elements relevant to an observer or active agent operating within that space.
Enzymatic activity – It refers to the measure of the catalytic ability of enzymes to convert substrates into products, which can be assessed through techniques which measure changes in substrate concentration or product concentration over time. This activity is influenced by the enzyme’s specificity for its substrate and can depend on the presence of cofactors.
Enzymatic bio-fuel cells – These are bio-electro-chemical devices which utilize oxido-reductase enzymes as bio-electro-catalysts to convert chemical energy into electrical energy by oxidizing a substrate at the anode and reducing a substrate at the cathode. These cells operate efficiently under mild conditions and are capable of processing organic bio-fuel molecules like alcohols.
Enzymatic reaction – It is a biochemical process which involves enzymes facilitating chemical transformations, which can occur in various solvents, including nonaqueous environments, improving applications in organic synthesis.
Enzymatic reactor – It is a system which utilizes immobilized enzymes on solid supports to facilitate bio-chemical reactions, allowing for increased reaction rates and cost-effectiveness through enzyme reuse and reduced contamination.
Enzymatic treatment – It is an environmentally friendly technique which utilizes enzymes to selectively remove hydrophilic components such as pectin, lignin, and hemicellulose from natural fibres, hence improving fibre-matrix adhesion and improving the mechanical properties of polymer composites.
Enzyme bio-catalysis – It is the use of enzymes to facilitate chemical transformations in industrial processes, leveraging microbial enzymes for their selective and efficient catalytic properties. This approach includes the application of both immobilized and free bio-catalysts to produce fine and bulk chemicals, contributing to economic and ecological benefits.
Enzyme cocktails – These refer to a mixture of cellulolytic enzymes and accessory proteins necessary for the efficient conversion of biomass to biofuels, often optimized through methods like sequential addition and blending.
Enzyme layer – It refers to a structure where enzymes are intercalated within the layers of host materials, typically layered metal oxides, enhancing their stability and accessibility to substrates while allowing for unique cooperative functions derived from both components. This configuration provides improved resilience under harsh conditions, such as high temperatures and organic solvents.
Eon – It is also spelled as aeon. It is an indefinably long period of time, frequently used to describe vast spans of history. In geology, it is the largest division of earth’s history, spanning hundreds of millions to billions of years, while in general usage, it means an extremely long, immeasurable quantity of time.
EPC contract – EPC stands for ‘engineer, procure and construct’. It describes a contract under which an engineering contractor undertakes to (i) design a process plant or power plant etc., or works with a heavy engineering element, normally to meet a specified level of performance, (ii) procure all components comprised in the design, and (iii) physically construct and test the plant. The equivalent term used in relation to more standard construction (e.g. housing, office blocks etc.) is ‘design-and-build’.
EPDM – It is the abbreviation for ‘ethylene propylene diene monomer’. It is a popular seal material which is compatible with fireproof hydraulic fluids, ketones, hot and cold water and alkalis. But it is not compatible with majority of the oils, gasoline, kerosene, aromatic and aliphatic hydro-carbons, halogenated solvents and concentrated acids.
Ephemeral water – It refers to bodies of water, like streams, rivers, or wetlands, that exist only temporarily during or shortly after periods of rainfall or snowmelt, drying up and becoming dry channels or beds during drier periods.
Epicentre – In seismology, it is the point on the earth’s surface directly above a hypo-centre or focus, the point where an earthquake or an underground explosion originates.
Epicerol – It is a proprietary bio-based technology developed by Solvay for producing epichlorohydrin from natural glycerin, which is obtained as a by-product of biofuel production. This process is characterized by its cost competitiveness and eco-efficiency, achieving a 60 % lower carbon di oxide (CO2) balance compared to conventional methods.
Epichlorohydrin – It is the basic epoxidizing resin intermediate in the production of epoxy resins. It contains an epoxy group and is highly reactive with polyhydric phenols such as bisphenol A.
Epicyclic gear train – It is a gear system where one or more gears rotate around another fixed gear, allowing for high velocity ratios in a compact space. It can be categorized as simple or compound and is normally used in applications such as differential gears and driving mechanisms in machinery.
Epigenetic – It is the orebodies formed by hydrothermal fluids and gases that were introduced into the host rocks from elsewhere, filling cavities in the host rock.
Epipolar constraint – It is a foundational rule in computer vision and multi-view geometry which defines the relationship between corresponding points in two images of the same 3D scene. It states that for a given point in one image, its corresponding point in a second image is to lie on a specific straight line known as the epipolar line.
Epipolar geometry – It refers to the geometry which describes the relationship between a pair of images taken by two cameras or different locations of a mobile camera. It involves the concept of epipolar lines and the ‘fundamental matrix’ to represent the projective motion between uncalibrated perspective cameras.
Epipolar geometry constraint – It is the geometric relationship between the image projections of a 3D point observed from two different camera positions, which ensures that corresponding points in the two images lie on a common epipolar line. This constraint is derived from the coplanarity of the vectors associated with the image points and the relative camera positions.
Epipolar lines – These are the straight lines of intersection formed when an epipolar plane (a plane passing through a 3D point and both camera centres) cuts across the image planes of a stereopair. They define the specific line in one image where a point from the first image must lie, restricting correspondence searches from a 2D area to a 1D line.
Epipolar plane image – It is a 2D image slice extracted from a 4D light field or a dense sequence of images taken by a moving camera. It typically plots one spatial coordinate of the scene against the camera position over time, making it highly useful for 3D reconstruction and depth estimation. Epipolar plane images are normally utilized for estimating depth information in light field imaging.
Epipole – It is a specialized point in computer vision and photogrammetry, representing the intersection of the baseline (the line connecting the optical centres of two cameras) with an image plane. In a stereo vision setup, where two cameras are capturing a scene from different locations, the epipoles (frequently denoted e and e’) are important for narrowing down the search space for corresponding pixels between images.
Epitaxial film – It is a crystalline layer formed on a substrate with a well-defined orientation, resulting from the process of epitaxy. This film shows a precise geometric relationship with the underlying crystalline material.
Epitaxial graphene – It is a type of graphene grown directly on a crystalline substrate (normally silicon carbide) through thermal decomposition. Unlike exfoliated graphene, which is a single detached sheet, epitaxial graphene consists of a carbon-rich buffer layer followed by one or more graphene layers, structurally and electronically coupled to the substrate.
Epitaxial hetero-structure – It is an artificially engineered, layered nano-material which combines different crystalline materials with precise atomic alignment at their boundaries. By merging distinct materials, engineers can create unique electrical, optical, and catalytic properties which neither material possesses on its own.
Epitaxial layer – It is a highly pure, thin crystalline film grown on top of a base crystalline substrate. The atoms of this deposited layer perfectly align with and continue the crystallographic pattern of the substrate beneath it.
Epitaxy – It is the growth of an electro-deposit or vapour deposit in which the orientation of the crystals in the deposit are directly related to crystal orientations in the underlying crystalline substrate.
Epithermal deposit – It is a mineral deposit consisting of veins and replacement bodies, normally in volcanic or sedimentary rocks, containing precious metals or, more rarely, base metals.
Epoxide – It is the compound containing the oxirane structure, i.e., a three-member ring containing two carbon atoms and one oxygen atom. The most important members are ethylene oxide and propylene oxide.
Epoxide equivalent weight – It is the weight of a resin (in grams) which contains one gram equivalent of epoxy.
Epoxidized linseed oil – It is a bio-based chemical derivative of flaxseed (linseed) oil, created by chemically converting its natural double bonds into highly reactive epoxide groups. This modification enhances the oil’s stability, chemical resistance, and reactivity, making it a versatile, renewable ingredient in modern manufacturing.
Epoxidized methyl oleate (C19H34O3) – It is a bio-based, modified fatty acid methyl ester produced through the epoxidation of methyl oleate (derived from plant or vegetable oils). It introduces highly reactive epoxide (oxirane) rings into the fatty acid chain, transforming it into an environmentally friendly chemical intermediate.
Epoxidized oils – These are bio-based chemical intermediates created by converting naturally occurring double bonds in unsaturated vegetable oils into highly reactive oxirane (epoxy) rings using hydrogen peroxide and organic acids. A common type of epoxidize oil id epoxidized linseed oil (ELO).
Epoxy – It is the resin formed by the reaction of bisphenol and epichlorohydrin.
Epoxy adhesive – It is a high-strength, two-part structural adhesive made by mixing an epoxy resin and a hardener. When combined, they trigger a chemical reaction which cures into a rigid, durable, and waterproof plastic. It is highly versatile and capable of bonding dissimilar materials. Epoxy adhesive is a high-performance structural and engineering adhesive known for its exceptional bonding strength and versatility, capable of adhering to metal, glass, ceramics, and plastics, while offering unmatched heat and chemical resistance.
Epoxy coating – It is a two-part system consisting of an epoxy resin and a hardener, which when mixed and applied, creates a hard, chemical and solvent-resistant finish. It is normally used to protect surfaces such as concrete and steel from water, alkali, and acids, though its brittleness can limit its applications unless toughening agents are incorporated.
Epoxy composites – These are advanced materials made by combining an epoxy resin matrix with reinforcing fibres (like carbon, glass, or aramid) or fillers. This combination creates a strong, lightweight, and corrosion-resistant structure widely used in demanding industries like wind energy.
Epoxy content – It refers to the concentration of reactive epoxide groups (also known as oxirane rings) present within a polymer chain, typically measured in moles per kilogram or as an equivalent weight. It indicates the density of reactive sites, which directly dictates the resin’s reactivity, cross-linking ability, and resulting hardness when cured.
Epoxy curing agents – These are also called hardeners. These are chemical compounds, normally polyamines or acid anhydrides, added to epoxy resin to initiate a polymerization reaction. They transform liquid resin into a solid, cross-linked, three-dimensional thermoset structure, providing mechanical strength, heat resistance, and adhesion to the final product.
Epoxy equivalent weight – It is the weight of epoxy resin in grams which contains 1 mole (or one equivalent) of epoxide (oxirane) groups. It is a critical parameter used to determine the correct stoichiometric quantity of curing agent (hardener) needed to achieve optimal physical and mechanical properties in the cured polymer, normally determined through titration.
Epoxy glass – It is also called glass epoxy or fibre-glass reinforced epoxy. It is a durable, high-strength composite material made by weaving glass fibres into a cloth and binding them with a hardened thermosetting epoxy resin. It is highly valued for its lightweight nature, excellent electrical insulation, and resistance to heat and chemicals.
Epoxy grout – It is a high-performance material used to fill gaps between tiles. Unlike traditional, cement-based grout, it is made from epoxy resins and a hardening powder. It hardens through chemical reaction rather than evaporation, resulting in a completely non-porous, waterproof, and highly durable finish.
Epoxy laminate – It is a high-performance composite material made by stacking multiple layers of reinforcing fabric, such as woven fibre-glass or carbon fibre, and bonding them together with a hardened epoxy resin. This material is known for its exceptional strength, heat resistance, and electrical insulation.
Epoxy material – It is a two-part resin which can be used as an adhesive, potting material, or paint, characterized by controllable parameters such as viscosity and setting time, and known for its good insulating properties and mechanical strength. It is normally used in applications like epoxy bonded fibre-glass and can be machined to size after curing.
Epoxy matrix – It is a continuous polymer phase created by curing an epoxy resin with a hardener, resulting in a robust, cross-linked thermosetting plastic. It is widely used in advanced composites to bind together reinforcing materials (like carbon or glass fibres) because of its high strength, heat resistance, and excellent adhesion.
Epoxy mortar – It is a high-strength, two-component mixture made by blending epoxy resin with a hardening agent and graded silica sand or quartz aggregates. Unlike standard cement-based mortars, it cures chemically rather than through evaporation, delivering superior adhesion, chemical resistance, and heavy-duty load-bearing capacity.
Epoxy nylon – It typically refers to a high-performance structural adhesive or composite material which blends epoxy resins with nylon (polyamide). Epoxy acts as a rigid, heat-resistant matrix, while nylon provides enhanced flexibility, peel strength, and impact resistance.
Epoxy patch – It is a heavy-duty, high-strength repair material used to fill holes, cracks, or surface damage in materials like concrete, masonry, or metal. It is created by mixing an epoxy resin, a hardener, and frequently an aggregate, which chemically bond to cure into a solid, durable surface.
Epoxy plastic – It is a polymerizable thermoset polymer containing one or more epoxide groups and curable by reaction with amines, alcohols, phenols, carboxylic acids, acid anhydrides, and mercaptans. It is an important matrix resin in composites and structural adhesive.
Epoxy polyamides – These are durable, two-part protective coatings and structural adhesives created by blending standard epoxy resins with reactive polyamide hardeners (curing agents). They are prized for their exceptional flexibility, strong adhesion, and superior water and corrosion resistance.
Epoxy pre-polymer – It is the main component of a reactive system, which can be di, tri, or tetra functional molecules, with di-glycidyl ether of bisphenol A (DGEBA) being a widely used variant. Depending on the degree of polymerization, epoxy pre-polymers can be either liquid or solid and can react with different chemical groups such as amines and anhydrides.
Epoxy reactive diluent – It is a low-viscosity, epoxy-functional compound added to epoxy resins to reduce thickness (viscosity) for easier application. Unlike non-reactive solvents, they chemically react during the curing process to become part of the polymer matrix, ensuring low VOC (volatile organic compound) emissions and maintaining mechanical properties.
Epoxy resins – These are a class of thermoset materials which are used extensively in structural and specialty composite applications since they offer a unique combination of properties which are not attainable with other thermoset resins. They are available in a wide variety of physical forms from low-viscosity liquid to high-melting solids. They are amenable to a wide range of processes and applications. Epoxy resins offer high strength, low shrinkage, excellent adhesion to different substrates, effective electrical insulation, chemical and solvent resistance, low cost, and low toxicity. They are easily cured without evolution of volatiles or by-products by a broad range of chemical specie. Epoxy resins are also chemically compatible with majority of the substrates and tend to wet surfaces easily, making them especially well-suited to composites applications. Epoxy resins are routinely used as adhesives, coatings, encapsulates, casting materials, potting compounds, and binders.
Epoxy resin system – It is a two-part high-performance plastic which cures into a rigid, durable solid. It consists of an epoxy base resin and a chemical hardener / curing agent. When mixed, they undergo a heat-releasing, irreversible chemical reaction called cross-linking.
Epoxy ring opening – It is also called epoxide ring-opening. It is a chemical process where a highly strained, three-membered cyclic ether, an epoxide, is cleaved to form a linear molecule. Since the bond angles in the ring are highly strained, the ring is incredibly reactive and readily opens when attacked by a nucleophile.
Epoxy silicone – It is also called epoxy-modified silicone. It is a high-performance hybrid material which combines the chemical and structural properties of epoxy resins with those of silicone resins. It bridges the gap between the rigid, chemical-resistant nature of epoxy and the flexible, high-temperature resilience of silicone.
E-procurement – It is also called electronic procurement process. It refers to requisitioning, ordering, and purchasing of goods and services online. It is normally a business-to-business (B2B) transaction. The E-procurement system, unlike E-commerce, is a closed system accessible only to registered users. With E-procurement, customers and preferred suppliers can interact through bids, purchase orders, and invoices. E-procurement connects suppliers and customers through a web interface or other networked systems. The enterprise’s procurement department or chief procurement officer is normally responsible for setting policies governing e-procurement.
Epsilon – It is a designation normally assigned to intermetallic, metal-metalloid, and metal-non-metallic compounds found in ferrous alloy systems, e.g., Fe3Mo2, FeSi, and Fe3P.
Epsilon carbide – It is a metastable, hexagonal close-packed (hcp) transition iron carbide with a chemical formula normally between iron (II) carbide (Fe2C) and iron (III) carbide (Fe3C), frequently cited as Fe2.4C, which forms during the early stages of tempering martensitic steels between 100 deg C to 200 deg C. It precipitates as fine, needle-like particles, contributing to high strength and hardness before transforming into stable cementite at higher temperatures.
Epsilon carbo-nitrides – These are also referred to as epsilon-iron carbo-nitrides or epsilon-phases. These are hexagonal interstitial compounds formed on the surface of iron-based materials during thermal chemical surface treatments like nitro-carburizing. They form as part of a compound layer (or white layer) which improves wear resistance and fatigue strength.
Epsilon nitrides – These are a type of interstitial iron nitride phase, typically denoted as (epsilon Fe2-3N or epsilon {FexN) with 2 below or equal to ‘x’ below or equal to 3), which form on the surface of iron and steel during thermochemical heat treatments like nitriding and nitro-carburizing. They are characterized by a hexagonal close-packed (hcp) crystal structure, where small nitrogen atoms occupy the interstitial voids in the iron lattice.
Epsilon structure – It is structurally analogous close-packed phases or electron compounds which have ratios of seven valence electrons to four atoms.
Epsom salt – It is the common name for magnesium sulphate heptahydrate (MgSO4.7H2O). It is a white, crystalline, inorganic salt which acts as a source of magnesium and sulphate, frequently found as a hydrated mineral known as epsomite. It is a naturally occurring mineral compound of normally used as a fertilizer. It appears as colourless or white crystals which dissolve in water.
Equal – It means being the same in quantity, size, degree, value, or status. It indicates a balance or uniformity where different elements or entities share the exact same traits, privileges, or measurements without distinction.
Equal angle – It is a type of structural steel shape characterized by its L-shaped cross-section with two legs of equal length. These legs are perpendicular to each other, forming a 90-degree angle. This shape is normally used in construction and engineering where support or framework is needed.
Equal-channel angular extrusion – It is a severe plastic deformation (SPD) process used to refine the grain structure of materials, improving their mechanical properties. It involves pressing a billet through a die with two intersecting channels of equal cross-section, causing the material to undergo a large shear deformation while maintaining its overall shape and dimensions.
Equal channel angular pressing – It is a severe plastic deformation technique used to refine and shrink the grain size of metals and alloys. By forcing a material through a die with two channels of equal cross-section intersecting at a specific angle (normally 90-degree), the material undergoes intense shear deformation without changing its overall dimensions.
Equal-cost multi-path – It is a routing technique used in computer networks to distribute the traffic to be distributed across multiple, parallel paths to a single destination, provided they have the same routing cost (metric). It improves network performance through load balancing, allows congestion control, increases throughput, and improves fault tolerance, making it important for the organization.
Equal error rate – It is the error rate at which the false accept rate (FAR) equals the false reject rate (FRR) value, used to evaluate system performance in verification mode.
Equality constraint – In optimization, it is a mandatory condition needing a function of decision variables to equal a specific value, normally expressed as ‘h(x) = 0’. These constraints strictly define the feasible region, reducing the problem’s dimensionality by forcing solutions to lie on a specific surface or boundary.
Equalization of heat flow – It refers to the process where thermal energy transfers from a hotter region to a colder region takes place until both reach the same temperature, at which point the net heat transfer stops. This phenomenon is driven by a temperature gradient i.e., heat moves from high-temperature areas to low-temperature areas.
Equalize – It means to make things even, uniform, or comparable in size, quantity, or value. It normally involves compensating for differences so that parts, people, or situations are brought into alignment or an equal state.
Equalized image – It is a processed digital image where pixel intensities are redistributed to spread across the entire available dynamic range, considerably improving global contrast. This is achieved using histogram equalization, a technique which adjusts brightness values so that the image’s histogram, representing the frequency of pixel values, is as uniform as possible.
Equalizer – It is a circuit used at the transmitter and / or receiver to correct for signal distortion caused by the transmission medium, producing an equal and opposite effect to the low-pass filtering. It deliberately distorts the transmitted signal so that it appears normal at the receiver, and can use techniques such as peaking amplifiers for restoring high-frequency content.
Equal-loudness contour – It is also known as an isophonic curve. It is a graph which plots the sound pressure level needed for different frequencies to be perceived as equally loud by the human ear. These contours quantify how the ears perceive certain frequencies as louder or softer even when their physical sound intensity (in decibels) is identical.
Equal percentage flow characteristics – It is an inherent flow characteristic in which equal increments of rated travel ideally give equal percentage changes of the existing flow.
Equal percentage valve – It is a control valve which produces equal valve stroke for equal increments in valve travel. This is the most common type of valve.
Equal power allocation – It is a method which uniformly distributes available transmission power across multiple users, antennas, or frequency subcarriers, regardless of individual channel conditions, signal quality, or user demand. It contrasts with dynamic methods like water-filling, which adjust power based on varying conditions.
Equating coefficients – These are also called comparing coefficients. It is an algebraic method used to find unknown variables in mathematical identities or polynomial equations. It is based on the principle that if two polynomial expressions are identically equal, the coefficients of matching variable powers on both sides are to be identical.
Equation log – It refers to a mathematical representation which relates the logarithmic values of variables in a linear format, allowing for the plotting of data to derive parameters such as slope and intercept, as shown in the context of tool life calculations.
Equation model – It uses mathematical equations to define relationships between variables. It serves as a simplified representation of a real-world system, physical process, or theoretical hypothesis. This approach is widely applied across different fields.
Equations for mass – These are mathematical expressions which represent the conservation of mass in different processes, such as fluid flow and electro-chemical reactions, and include terms for mass accumulation and mass flux changes.
Equation of constraint – It is a mathematical relation which restricts the possible positions, velocities, or motions within a physical or mathematical system. By reducing the number of independent variables, it defines the degrees of freedom available to the system.
Equation of continuity – It is a mass balance of a fluid flowing through a stationary volume element, stating that the rate of mass accumulation equals the rate of mass entering minus the rate of mass exiting the volume.
Equation of state – It is a thermodynamic expression which mathematically relates state variables. typically pressure (P), volume (V), and temperature (T), to describe the state of matter under specific physical conditions. The fundamental thermodynamic relations provide frameworks for these equations, which range from simple models to highly complex calculations used across physics, chemistry, and engineering.
Equation turbulence model – It refers to a mathematical framework in computational fluid dynamics (CFD) used to simulate turbulent fluid flows. Since resolving every single eddy needs immense computing power, these models use simplified equations to estimate how turbulence impacts the overall, time-averaged flow field. These models typically fall into two main categories depending on the number of transport equations they use one-equation models, and two-equation models.
Equator – In filament winding, it is the line in a pressure vessel described by the junction of the cylindrical portion and the end dome. It is also called tangent line or point.
Equatorial plane – It is an imaginary, two-dimensional flat plane which passes through the centre of a celestial body (like a planet or moon) and its equator. It is strictly perpendicular to the axis of rotation and divides the object into northern and southern hemispheres.
Equi-axed grains -These are crystalline structures in metals or alloys where the grains have approximately equal dimensions in all directions (aspect ratio typically 2.5 and below). Unlike elongated or columnar grains, they lack a directional bias, yielding uniform, isotropic mechanical properties throughout the material.
Equi-axed grain structure – It is a structure in which the grains have approximately the same dimensions in all directions.
Equi-axed powder – It consists of particles having approximately equi-dimensional non-spherical shapes.
Equi-axed solidification behaviour – It refers to a solidification mode in materials, typically metal alloys, characterized by the formation of roughly spherical, randomly oriented, and uniform crystals (grains) rather than long, elongated columnar crystals. This type of solidification occurs within the ‘mushy zone’ of a casting, where the solid and liquid coexist, particularly in the central region where temperature gradients are low.
Equiaxed zone – It is the central region in a metal casting or ingot characterized by randomly oriented, roughly spherical (equiaxed) grains. This zone normally forms when detached dendrite fragments act as growth centres, halting the inward advance of elongated, directional columnar grains and promoting uniform mechanical properties.
Equi-cohesive temperature – It is the temperature at which the strength of a metal’s grain boundaries equals the strength of the grain interiors. Below this temperature, grains are weaker and fractures are transgranular. Above it, boundaries are weaker, leading to intergranular fractures and grain boundary sliding.
Equi-distant interval – It is a segment of measurement, time, or space where the distance between each point, boundary, or marking remains perfectly equal. It combines equidistant (the same distance) and interval (a gap or period).
Equi-distribution – It is a property of a sequence of numbers (or points) evenly spread out within a specific space or interval, such that the proportion of terms falling into any given sub-region is proportional to its size.
Equilateral triangle – It is a geometric polygon with three sides of equal length. Since its sides are equal, all three interior angles are also equal, each measuring exactly 60-degree. It represents a regular polygon and is a special case of an isosceles triangle.
Equilateral triangular duct – It is a conduit, pipe, or channel with a constant cross-section shaped like an equilateral triangle (three equal sides and three 60-degree angles). It is widely used in compact heat exchangers, gas turbines, and electronics cooling for its unique thermal and hydrodynamic properties.
Equilateral triangular prism – It is a 3D solid with two parallel, congruent equilateral triangle bases (sides of equal length and 60-degree angles) and three rectangular faces connecting them. It is a pentahedron (5 faces, 9 edges, 6 vertices).
Equilibrium – It is the dynamic condition of physical, chemical, mechanical, or atomic balance which appears to be a condition of rest rather than one of change.
Equilibrate – It refers to the process of achieving a stable state in a system, where parameters such as pH and pCa reach consistent values over time, frequently needing extended durations to ensure accurate measurements, particularly in the context of zeta potential studies.
Equilibration – It is the process where a metal or alloy reaches a state of minimum energy and maximum stability. During this state, temperature, composition, and phase fractions remain constant over time, with opposing metallurgical reactions (like melting and solidifying) occurring at equal rates.
Equilibrium, alloy phases – There are three types of equilibria namely stable, meta-stable, and unstable. Stable equilibrium exists when the object is in its lowest energy condition. Meta-stable equilibrium exists when additional energy is to be introduced before the object can reach true stability. Unstable equilibrium exists when no additional energy is needed before reaching meta-stability or stability. Although true stable equilibrium conditions rarely exist in metal objects, the study of equilibrium systems is extremely valuable, since it constitutes a limiting-conditions from which actual conditions can be estimated.
Equilibrium boundary layer – It is frequently referred to in the context of phase diagrams as the local equilibrium layer or diffusion layer. It is the microscopic region near a liquid-solid interface during solidification or melting. It defines the thin zone of liquid where diffusion occurs and compositions match thermodynamic equilibrium.
Equilibrium branch – It refers to a stable pathway on a phase diagram or a specific thermodynamic trajectory where an alloy’s phases, defects, or structures exist in a state of minimal free energy. It represents the idealized, thermodynamically stable state of a material under a specific set of conditions.
Equilibrium catalyst – It is the circulating mix of aged, regenerated, and fresh catalytic particles actively used in large-scale industrial processes, particularly fluid catalytic cracking (FCC) in petroleum refining. It represents a steady state where fresh catalyst is continuously added to balance out the gradual loss of activity.
Equilibrium composition – It refers to the specific quantities, concentrations, or partial pressures of all reactants and products present in a chemical or physical system once it has reached equilibrium. At this stage, the forward and reverse reaction rates are equal, resulting in no net change in the mixture over time.
Equilibrium condition – It refers to the state where an alloy’s microstructure and phase composition are at their most stable, lowest Gibbs free energy level. It is achieved through extremely slow heating or cooling, giving atoms sufficient time to diffuse and form phases dictated by a phase diagram.
Equilibrium configuration – It is the most thermodynamically stable state of an alloy at a specific temperature and pressure. It occurs when the Gibbs free energy is at its absolute minimum, resulting in a perfectly balanced structure where no spontaneous transformations, such as phase changes, occur. It also refers to the state of an elastic body in which the internal forces balance the external forces, resulting in a stable and unique configuration which can be determined using principles such as virtual power or minimum total potential energy.
Equilibrium concentration – It refers to the specific proportion of solute atoms (alloying elements) dissolved within a solvent metal when the system reaches its lowest possible Gibbs free energy at a given temperature. At this point, the phase composition remains stable over time.
Equilibrium constant (Keq) – It is a thermodynamic value which quantifies the extent to which a specific chemical reaction, such as the reduction of an ore, oxidation, or slag-metal refining, reaches a state of balance. It represents the ratio of the chemical activities of the products to the reactants once a reversible reaction reaches dynamic equilibrium.
Equilibrium contact angle – It is the angle formed at the intersection of a liquid, gas, and solid phase. It quantitatively measures wettability (e.g., how well molten metal or slag spreads over a solid metal, ceramic mould, or refractory). It is the internal angle measured through the liquid phase, from the solid surface to the liquid-vapour interface.
Equilibrium criterion – It defines the exact conditions under which a metallic system exists in a state of balance without spontaneous changes. It mainly needs the system to be at its minimum Gibbs free energy (G), meaning no driving force exists for further phase transformations, chemical reactions, or mass transfer.
Equilibrium crystal – It refers to a crystal which has achieved its most thermodynamically stable shape by minimizing its total surface free energy. It represents the ideal geometric form which a metallic crystal or grain naturally seeks to adopt when all interfacial, structural, and chemical forces are completely balanced.
Equilibrium curve – It refers to specific boundaries on a phase diagram (such as a temperature vs. composition graph) which separate different phases of a metal alloy. These curves identify the temperatures and compositions at which phase changes occur under theoretical, slow-cooling conditions. The two most common equilibrium curves are the liquidus and solidus lines.
Equilibrium data – It refers to the thermodynamic and phase information which dictates how alloys and metals behave under completely stable conditions (where temperature, pressure, and chemical composition remain constant over time). This data is mainly used to construct phase diagrams.
Equilibrium diagram – It is a graph of the temperature, pressure, and composition limits of phase fields in an alloy system as they exist under conditions of thermodynamical equilibrium. In metal systems, pressure is normally considered constant.
Equilibrium distribution function – It describes how a solute partitions itself between two phases (such as a solid and a liquid) when a system reaches thermodynamic equilibrium. Mathematically, it is frequently represented as the equilibrium partition (or distribution) coefficient, denoted by the symbol (k).
Equilibrium efficiency – It measures how closely an actual industrial separation process (such as leaching or solvent extraction) approaches the theoretical maximum separation achievable under perfect thermodynamic equilibrium. It is expressed as a ratio of the actual change in concentration to the equilibrium change.
Equilibrium electrode potential – It is a static electrode potential when the electrode and the electrolyte are in equilibrium with respect to a specified electro-chemical reaction.
Equilibrium equation – It defines the state where the forward and reverse reactions of a system (such as in slag-metal reactions, oxidation / reduction, or dissolution) occur at the exact same rate, or when the chemical potential of a component is equal across different coexisting phases.
Equilibrium gamma – It refers to the stable phase of a nickel-based superalloy which coexists with the gamma’ phase, characterized by specific composition ratios which maintain a consistent balance under given conditions.
Equilibrium line – It is a boundary on a phase diagram which indicates the temperatures and compositions at which different phases of a metal or alloy coexist in thermodynamic equilibrium. It represents the conditions where phase transformations (such as melting or solidification) occur under infinitely slow, fully reversible conditions.
Equilibrium load – It normally refers to a mechanical or chemical state of balance. It refers to a balanced state of forces where all external loads and internal reactions nullify each other. In this state, the vector sum of all forces and moments is zero, resulting in no linear or angular acceleration.
Equilibrium method – It describes materials under conditions of near-infinite cooling or heating, where a system reaches its most thermodynamically stable state. It dictates the baseline phases, compositions, and structures a metal form when given enough time for all atomic diffusion and reactions to fully complete.
Equilibrium model – It is a thermodynamic framework which predicts the stable phases, composition, and transformations of a material (like an alloy) under the assumption that it has reached a state of perfect balance.
Equilibrium moisture content – It refers to the stable state where a material, such as a metal powder or porous casting, neither gains nor loses moisture when exposed to a specific, constant ambient relative humidity and temperature. At this point, the vapour pressure of the moisture in the material matches the vapour pressure of the surrounding air. It is the specific moisture level a hygroscopic material reaches when it is in balance with the surrounding air’s temperature and humidity, resulting in no further net gain or loss of moisture. It is the stability point where the material neither dries out nor absorbs water.
Equilibrium modulus – It is the elastic response of a material when all time-dependent viscous or relaxation processes have fully ceased. It is the long-term or ‘static’ stiffness of a material, measured as the low-frequency asymptote of the dynamic modulus.
Equilibrium moisture content – It is the specific state where a material’s internal moisture is perfectly balanced with the ambient temperature and relative humidity of its surrounding environment. At this point, the material neither absorbs water from the air nor releases its own moisture. This concept is mainly applied in powder metallurgy (where powders can absorb moisture from the air), pelletizing, and the preparation of raw materials (like ores and coke) for sintering or smelting.
Equilibrium morphology – It is the physical shape or microstructure a crystalline phase naturally adopts when its overall Gibbs free energy and surface tension are minimized at a specific volume. It dictates the thermodynamically stable boundaries of grains and precipitates in an alloy, though it is frequently altered by non-equilibrium processing.
Equilibrium, phase – It is a stable thermodynamic state where two or more phases (solid, liquid, or gas) coexist without any net change in their quantities over time. It occurs when temperature, pressure, and chemical potentials are uniform across all phases, such as when evaporation equals condensation in a sealed container.
Equilibrium phase diagram – It is a graphical representation showing the stable regions of substances or solutions within a chemical system as a function of temperature and composition, showing where phases coexist. It serves as a powerful tool for predicting the state of a system under varying conditions.
Equilibrium point – It refers to a specific condition or location on a phase diagram, such as an alloy’s composition and temperature, where the system’s phases (e.g., solid, liquid) exist in thermodynamic balance, meaning no further spontaneous changes occur and chemical potentials are equalized. These points define where distinct phase transformations occur.
Equilibrium position – It is a state in which a system remains stationary in the absence of external interference, characterized by the condition where the derivatives of the state satisfy zero, indicating that the system is not subject to net forces or changes.
Equilibrium potential – It is also called reversible potential. It is the potential of an electrode in an electrolytic solution when the forward rate of a given reaction is exactly equal to the reverse rate. The equilibrium potential can only be defined with respect to a specific electro-chemical reaction.
Equilibrium pressure – It is the specific partial pressure of a reactive gas (such as oxygen or carbon mono-oxide) at which a metal and its compound (like an oxide or carbide) exist in thermodynamic balance. At this exact pressure, the rates of formation and decomposition are equal, meaning no net oxidation or reduction occurs.
Equilibrium process – It is a theoretical thermodynamic change which occurs so slowly that the metal remains in a continuous state of balance. Since the system can continuously adjust, the process is perfectly reversible, meaning no net energy is lost and phase changes happen with minimal energy input. Since true equilibrium needs infinite time, actual industrial metallurgical processes are non-equilibrium processes. However, thermodynamics relies heavily on these theoretical benchmarks to predict phase limits and final alloy structures.
Equilibrium reaction – It refers to a reversible process where a forward reaction (such as a phase change or chemical reduction) occurs at the same rate as its reverse reaction. This results in a stable state where the proportions of reacting materials and resulting products no longer change over time.
Equilibrium reaction equation – It defines the point where the rate of a forward metallurgical reaction (e.g., oxidation, smelting) equals the reverse reaction rate, or where phases coexist in thermodynamic harmony (like melting and freezing).
Equilibrium shape – It refers to the specific geometry a crystal or grain assumes when its total surface free energy is minimized. It dictates how facets, curved surfaces, and edges balance to achieve thermodynamic stability, frequently modelled using the Wulff construction.
Equilibrium situation – It refers to the state where a metal alloy reaches its lowest possible Gibbs free energy at a specific temperature and pressure. In this balanced state, the microstructure and phase composition of the material remain perfectly stable over time.
Equilibrium spin – It refers to the state where the intrinsic angular momentum (spin) of particles in a system is symmetrically balanced, resulting in a net-zero total magnetization under thermodynamic conditions.
Equilibrium state – It is a condition of balance within a system where opposing forces, processes, or actions perfectly counteract one another. As a result, there is no overall net change in the system’s observable properties, and it remains stable over time.
Equilibrium steady state – It is a condition in a dynamic system where state variables remain constant over time since the rate of input exactly equals the rate of output. No net changes occur, as all opposing forces or processes perfectly balance each other. The concept can be broken down by looking at the two underlying ideas namely equilibrium and steady state.
Equilibrium step – It normally refers to a stage in a scientific process, very frequently a chemical reaction, where a state of balance has been reached. In case of chemical equilibrium, an equilibrium step occurs in a reversible reaction when the rate of the forward reaction equals the rate of the reverse reaction. In case of mechanical equilibrium, an equilibrium state is reached when all opposing forces or influences acting on a system are perfectly balanced. In case of thermodynamics (phase equilibrium), an equilibrium step or process involves two or more phases of matter (e.g., solid and liquid) where no net transfer of mass or energy occurs between them. In market analysis, equilibrium step represents the point where supply exactly meets demand.
Equilibrium strategy – It is very frequently associated with the Nash equilibrium. It is a set of choices made by players in a game or economic scenario where no player can improve their outcome by unilaterally changing their strategy, assuming the other players keep theirs unchanged. At this strategic balance, every participant’s chosen move is their absolute best response to the moves chosen by everyone else. Since no one has anything to gain by doing something differently, the situation remains stable.
Equilibrium temperature – It is the final, stable temperature reached when two or more systems (or substances) exchange heat until no net heat transfer occurs. At this point, the substances are in thermal equilibrium, meaning they share the same temperature and energy flows equally between them.
Equilibrium thickness – It refers to a state of physical balance where a specific dimension (such as a fluid film or ice layer) stops changing since competing forces or heat transfer mechanisms have perfectly canceled each other out.
Equilibrium vapour pressure – It is the pressure exerted by a metal or alloy’s vapour when its gaseous phase is in thermodynamic balance with its condensed phase (liquid or solid) in a closed system. At this point, the rate of vapourization exactly equals the rate of condensation.
Equipartition theorem – It relates the temperature of a system to its average energies. The equipartition theorem is also known as the law of equipartition, equipartition of energy, or simply equipartition. The original idea of equipartition has been that, in thermal equilibrium, energy is shared equally among all of its different forms, e.g., the average kinetic energy per degree of freedom in translational motion of a molecule is equal that in rotational motion.
Equipment – It is the set of tools, machinery, apparatus, or supplies needed to perform a specific activity, job, or function. It typically refers to tangible, long-term items used to achieve a particular purpose or produce goods and services.
Equipment capacity requirements – These requirements define the maximum and minimum production volume, speed, or performance a machine or system is to achieve to meet planned production goals within a specific timeframe. It bridges the gap between customer demand and available production resources, ensuring that machines can handle workloads efficiently without causing bottlenecks.
Equipment certification – It is the formal verification and documented proof which processing or testing machinery meets specific safety, performance, and industrial standards. It ensures that equipment, such as furnaces, casting machinery, and testing apparatus, operates accurately and safely under extreme conditions. The certification process normally focuses on three pillars namely calibration, inspection, and testing.
Equipment drawing – It is pertaining to equipment parts or components. It is presented through a number of orthographic views, so that the size and shape of the component is fully understood. Part drawings and assembly drawings belong to equipment drawing.
Equipment erection – It involves the assembly and installation of simple, large, and complex equipment. The process is complex and challenging which needs precise planning and execution. This needs expertise in engineering principles and techniques along with skilled workmen and engineers.
Equipment failure rate – It is the frequency at which a metal component or machine breaks down or degrades beyond functional use. It is mathematically defined as the total number of failures divided by the total operating time.
Equipment foundation – It is the super-structure of vibrating and rotating equipments. It essentially consists of a mass of reinforced concrete. Design of equipment foundation involves consideration of static and dynamic loads. Equipment foundation is specially designed to meet machinery loads, movements and other actions. These specific foundations can help protect flooring as you use machinery, enhancing working conditions for operators by absorbing vibrations and frequencies.
Equipment foundation system – In a broader sense, it comprises of equipment, supported by foundation resting over soil subjected to dynamic loads namely (i) generated by equipment itself, (ii) applied externally, or (iii) caused by external sources and transmitted through soil.
Equipment identity register – It is a secure mobile network database which stores and verifies the identity of physical devices using their ‘international mobile equipment identity’ (IMEI) numbers. It ensures only authorized, safe, and non-stolen hardware can access a cellular network.
Equipment item – It is a single, identifiable, and durable article, machine, or apparatus needed to perform a specific task, function, or operation. It is an individual physical unit which is functionally complete and typically used in an operation, trade, or project.
Equipment manufacture – It is the industrial process of producing machinery, tools, and technical systems used across the economy. Frequently called ‘machines that produce machines’, it spans different sectors like electronics, and industrial fabrication.
Equipment manufacturer – It is an organization which designs and produces parts, components, or complete systems. These items are either sold as finished goods or supplied to other organizations who integrate them into their own final products.
Equipment piping – It refers to the system of pipes, valves, fittings, and other components used to transport fluids (liquids and gases) within or between different pieces of equipment. These systems are crucial for several industrial processes, including refining, manufacturing, and power generation.
Equipment-register – It is a centralized database or inventory listing all machinery, tools, and assets used in engineering projects, facilities, or laboratories. It tracks critical details, such as ID (identity document), location, maintenance history, and certification status, ensuring compliance, safety, and efficient maintenance scheduling.
Equipment reliability operating envelope – It defines the specific, safe operating range for rotating equipment, particularly centrifugal pumps, which ensures freedom from hydraulic disturbances and minimizes component wear. It identifies the ‘heart of the curve’ where equipment operates reliably without premature failure. It is the range of flow (typically +10 %, -50 % of best efficiency point flow) designed to eliminate hydraulic disturbances and prevent damage.
Equipment requirement – It refers to the specific tools, machinery, software, or hardware needed to execute a particular task, project, or operational process. It establishes the technical standards, operating capabilities, and material constraints necessary for successful operation.
Equipment shutdown – It is the process of intentionally taking a machine or system offline from an active operational state to an inoperative one. It involves safely de-energizing, isolating, and powering down assets to perform maintenance, repairs, inspections, or to prevent catastrophic safety hazards.
Equipment supplier – It is an organization, manufacturer, or vendor which provides machinery, tools, or hardware needed to operate, maintain, or produce goods. They act as strategic partners across industries (like manufacturing), frequently handling equipment delivery, installation, staff training, and maintenance.
Equipment testing – It is the process of evaluating machinery, tools, or devices to verify their safety, reliability, and operational performance. It ensures equipment meets industry standards, identifies potential defects or hazards before use, and complies with regulatory requirements.
Equipment vendor – It is a manufacturer, distributor, or third-party seller which provides physical hardware, machinery, or technical tools. They mainly operate in business-to-business (B2B) supply chains and frequently provide value-added services like installation, staff training, and maintenance contracts.
Equi-potential – It is a region in space where every point is at the exact same electric or scalar potential. Since the potential is uniform, the potential difference between any two points on an equi-potential is zero. It refers to a line or surface where the velocity potential is constant, indicating that there is no flow along that line. In a fluid context, streamlines and equi-potentials intersect at right angles, meaning fluid flow is perpendicular to equi-potential lines.
Equi-potential curve – It is a line in a two-dimensional space where every point has the exact same scalar potential. The concept is widely used to map fields, such as electric, gravitational, or fluid flow, where a specific value (like voltage or pressure) remains constant.
Equi-ripple – It describes a design criterion where periodic fluctuations (ripples) in a system’s frequency response, very frequently seen in filters and amplifiers, are constrained to have identical, uniform heights. This minimax optimization approach minimizes the maximum possible deviation from an ideal target response.
Equity financing – It is the process of raising capital by selling shares of ownership in an organization to investors. Instead of taking out a loan, the organization exchanges partial ownership for cash, meaning there are no debt obligations or interest payments to repay.
Equity investor – Equity investor is an individual or entity who provides capital to an organization in exchange for partial ownership, sharing in both the risks and the rewards of the organizational operations. Unlike lenders, equity investors do not need the money to be paid back. Instead, they invest to grow their wealth through the success of the organization.
Equivalence class – It is a logical concept used to group items which behave in the exact same way under a specific set of rules or conditions. It divides a larger system or dataset into distinct subsets so that evaluating one item in a subset is identical to evaluating any other item in that same subset.
Equivalence principle – It is the foundational concept that the effects of a uniform gravitational field are locally indistinguishable from the effects of uniform acceleration. It describes how gravitational mass and inertial mass are identical, meaning all objects fall at the same rate regardless of mass.
Equivalence ratio – It is a dimensionless parameter in combustion engineering defined as the ratio of the actual fuel-to-oxidizer (e.g., air) ratio to the stoichiometric fuel-to-oxidizer ratio. It determines if a combustion mixture has an excess of fuel or air.
Equivalence relation – It is a logical relationship which allows people to group different elements based on shared characteristics. A relation is an equivalence relation if and only if it satisfies three fundamental properties namely reflexivity, symmetry, and transitivity.
Equivalent circuit – It is a simplified theoretical model which shows the exact same voltage, current, and frequency behaviour at its terminals as a more complex real-world device or system. It allows engineers to easily analyze, calculate, and predict system performance. The concept relies on a ‘black box’ approach. If people connect an external circuit to two exposed terminals, they cannot distinguish between the original complex system and its simplified equivalent circuit by simply measuring the inputs and outputs.
Equivalent circuit model – It is a simplified theoretical representation of a complex physical, or electrical system which uses ideal circuit components (resistors, capacitors, inductors, and voltage / current sources) to replicate the system’s exact terminal characteristics.
Equivalent circulating density – It is the effective density exerted by a circulating drilling fluid against the wellbore. It represents the sum of the fluid’s static hydrostatic pressure and the frictional pressure losses created by the fluid moving up the annulus.
Equivalent code – It refers to an alternative component, material, design, or standard which an ‘engineer of record’ (EOR) accepts to fulfill the exact same function, safety requirements, and performance parameters as the originally specified code.
Equivalent conductance – It is the conducting power of all the ions produced by exactly one gram-equivalent of an-electrolyte dissolved in a given volume of solution. It normalizes the measurement of electrical conductivity to allow for direct comparisons across different types of chemical solutions.
Equivalent creep strain – It is a scalar, time-dependent measure of cumulative, permanent inelastic deformation in a material subjected to constant load and high temperatures, normally defined as the accumulated uniaxial equivalent of a complex 3D multiaxial creep strain state, frequently based on the Von Mises criterion. It allows designers to predict total creep failure by comparing multi-axial simulation results to uniaxial experimental test data.
Equivalent damping ratio – It is a metric used to represent complex, non-linear, or structural energy dissipation as a single, simplified linear viscous damping value. It equates the actual energy lost in a cyclic vibration to the energy dissipated by an equivalent viscous damper.
Equivalent density – It is the apparent fluid density which creates the same pressure in a system as the combined static and dynamic forces. Very frequently used in drilling and fluid mechanics as ‘equivalent circulating density’ (ECD), it represents the total downhole pressure exerted on a wellbore.
Equivalent design – It refers to a substitute component, material, or system which functionally matches the original specification. It delivers the same performance, durability, safety, and efficiency without altering the project’s core parameters.
Equivalent diameter – It is a hypothetical diameter used to analyze non-circular shapes (like ducts or irregularly shaped particles) using standard mathematical equations, formulas, and correlations originally developed for perfect circles or spheres.
Equivalent dose – It is a dose quantity representing the stochastic health effects of low levels of ionizing radiation on the human body which represents the probability of radiation-induced cancer and genetic damage.
Equivalent flexural strength – It is a calculated value representing a material’s post-cracking bending capacity. It is mainly used in civil engineering to assess the toughness of fibre-reinforced concrete (FRC) by calculating the area under the load-deflection curve.
Equivalent full load hours – It is a metric used to calculate a system’s actual energy usage over a specific period. It is defined as the number of hours a piece of equipment needs to run continuously at its maximum (rated) capacity to consume the equivalent of its total actual energy consumed.
Equivalent hardness numbers – These are corresponding values from different hardness test methods (such as Brinell, Rockwell, or Vickers) which indicate around the same level of material resistance to plastic deformation or indentation. Since different methods measure hardness in unique ways, such as depth of penetration (Rockwell) or surface area of an indentation (Brinell / Vickers), conversion tables are used to relate these different scales to one another.
Equivalent heat capacity method – It is also known as the apparent or effective heat capacity method. It is a transient heat transfer modelling approach used to simplify complex phase-change problems (such as melting and solidification). It incorporates a material’s latent heat into its specific heat, allowing the system to be solved as a standard, single-phase non-linear conduction problem.
Equivalent homogeneous material – It is a theoretical abstraction used to model complex, heterogeneous structures. It represents a composite or layered material as a single, uniform substance which behaves identically to the original structure under identical mechanical, thermal, or electro-magnetic loads.
Equivalent impedance – It is the total, simplified impedance of a complex electrical circuit which replaces multiple components with a single, equivalent value. It preserves the exact voltage and current relationships at a specific pair of terminals, making it easier to calculate overall behaviour in AC (alternating current) circuits.
Equivalent inclusion method – It is a foundational micro-mechanics technique used to analyze heterogeneous materials (e.g., composites or poly-crystals) by mathematically replacing actual material defects or particles with simpler, homogeneous ‘inclusions’ which show the same stress and strain fields.
Equivalent initial flaw size (EIFS) method – It is a fatigue life prediction approach which models a complex material defect as a single, imaginary crack, growing it ‘backwards’ from a detected crack size to time-zero using a long-crack growth model. It simplifies fatigue analysis by replacing complex, small crack initiation processes with an initial crack size which yields equivalent results.
Equivalent input noise – It is the hypothetical noise which, if applied to the input of a perfectly noiseless amplifier, produces the same total noise at the output as the actual, practical amplifier. It is an important metric used to evaluate the internal noise added by a system to a signal.
Equivalent isotropic radiated power – It is the theoretical power a hypothetical isotropic antenna (which radiates equally in all directions) needs to emit to produce the same peak signal strength as an actual directive antenna in its strongest direction. It quantifies the true strength of a wireless transmission.
Equivalent linear model – It is an analytical technique used to approximate complex, non-linear systems by using linear, frequency-dependent material properties. By iteratively adjusting the system’s stiffness and damping parameters based on the strain or amplitude of motion, engineers can perform faster linear analyses that closely simulate the actual non-linear response.
Equivalent loading stress – It is a calculated scalar value which simplifies a complex, multiaxial stress state into a single uniaxial stress value. It is used to predict yielding or failure in ductile materials by comparing the combined stress state to a simple tensile test result, with the most common definition being Von Mises stress.
Equivalent materials – These are those materials which, while not identical, possess comparable properties, functionality, or characteristics, making them suitable as replacements or alternatives in a specific application.
Equivalent mud weight – It is the density a static fluid column needs to exert the exact same downhole pressure at a specific depth. Engineers use equivalent mud weight (EMW) to convert complex downhole pressures, such as those caused by circulating mud, friction, or formation surges, into a familiar, easy-to-compare density unit.
Equivalent network – It is a simplified theoretical model which replicates the exact terminal voltage and current relationships of a more complex original system. It is used to drastically reduce mathematical complexity while preserving the precise performance characteristics of the actual hardware.
Equivalent orifice – It is a conceptual tool used to quantify, simplify, and compare complex flow restrictions. It is defined as the area of an imaginary, idealized sharp-edged circular opening which allows the same volume of fluid (liquid or gas) to pass through as the actual, complex flow path, under an identical pressure difference.
Equivalent plane strain – It refers to a simplified two-dimensional modelling approach used to analyze vertical drains in ground improvement projects, transforming parameters from a three-dimensional axisymmetric condition to a two-dimensional plane strain condition for computational efficiency.
Equivalent plastic strain – It is a scalar quantity used in solid mechanics to quantify the magnitude of permanent, non-recoverable deformation in a material under complex, multi-axial stress states. It condenses multiple strain tensor components into a single value, making it easier to track material yielding and predict ductile failure.
Equivalent process – It refers to a process, design, or component which can differ in structure, composition, or method but produces the same output, performance, or behaviour under similar conditions. This concept is used to simplify complex systems, validate changes, or ensure product quality during testing. Two processes are equivalent if they take the same input and produce the same output.
Equivalent radial load – It is the level of constant radial load on a rolling-element bearing which, when the bearing is stationary with respect to the outer race, produces the same rating life as a given combination of radial and thrust loads under the same conditions of operation.
Equivalent replacement – It is the substitution of a component or material with an alternative which is not identical but performs the same function. The substitute is to meet identical design requirements, operational performance standards, and physical or software interface constraints as the original item.
Equivalent resistance – It is the single, total resistance which can replace an entire network of resistors in a circuit. It simplifies circuit analysis by ensuring that the voltage and current flowing through the rest of the circuit remain exactly the same as they are with the original, complex combination. Depending on how components are wired within the system, this aggregate value is calculated using specific mathematical formulas.
Equivalent Reynolds number – It is a modified Reynolds number used in fluid mechanics and heat transfer to predict fluid flow behaviour in non-circular geometries. It allows engineers to apply standard circular-pipe data to complex systems (like rectangular ducts or heat exchangers) by using the hydraulic diameter as the characteristic length.
Equivalent roughness – It is also called equivalent sand-grain roughness. It is an idealized, single length-scale value which characterizes an irregular, non-uniform surface. It represents the height of uniform sand grains which causes the same fluid flow resistance and frictional pressure drop as the actual surface.
Equivalent round – It is the diameter of a circle having a circumference equal to the outside perimeter of other than round tube.
Equivalent sand – It is a measure used to test the clay content in fine aggregates, calculated as the ratio of the height of settled sand to the height of suspended clay in a graduated cylinder, expressed as a percentage.
Equivalent sand grain roughness – It is a theoretical length scale used in fluid mechanics to characterize how an irregular, real-world rough surface affects fluid flow. It defines the physical height of uniformly sized, closely packed sand grains which causes the exact same quantity of friction and pressure drop as the actual surface.
Equivalent standard – It is an alternate technical guideline, material, or part accepted as a direct substitute for a originally specified one. It guarantees that the substitute delivers identical performance, quality, and safety as the original without altering the design’s overall integrity.
Equivalent stiffness – It is a single, theoretical spring constant which represents the overall resistance to deformation of a complex mechanical or structural system. It simplifies intricate setups, such as multiple connected springs, beams, or trusses, into a single, easy-to-analyze variable.
Equivalent strain – It is a scalar quantity used to describe a complex, multi-axial strain state (such as in forming or welding) as a single value, making it easier to predict plastic deformation or failure by comparing it directly to uniaxial tensile test results. It reduces individual strain components into one equivalent value, frequently based on the von Mises yield criterion.
Equivalent uniaxial strain – It is frequently called equivalent plastic strain, or von Mises strain. It is a single scalar value used to quantify the total magnitude of deformation, regardless of whether the material is subjected to complex multi-axial loading (such as in forming processes) or simple tension / compression.
Equivalent stress – It is a scalar value used to represent a complex, multi-axial stress state as a single uniaxial stress value. It enables designers to predict failure by comparing this single value against uniaxial tensile test results (like yield strength), especially for ductile materials. It reduces complex 3D stress tensors, composed of normal and shear stresses, into one equivalent uniaxial stress value.
Equivalent stress intensity factor – It is a single scalar parameter used in fracture mechanics to represent a complex, multi-axial crack condition (mixed-mode loading). It equates combined loading modes to an equivalent mode-I (opening mode) condition, allowing engineers to reliably predict crack propagation and structural fatigue.
Equivalent stress range – It is a single scalar value used to evaluate fatigue damage under varying, multi-axial operational loads. It translates a complex, fluctuating multi-axial stress state into a single, fluctuating uniaxial equivalent stress, which can be compared against standard fatigue life curves (S-N curves).
Equivalent temperature – It is a standardized metric used to simplify complex thermal environments. It is defined as the uniform temperature of an imaginary enclosure (or reference environment) where a subject experiences the same rate of heat exchange (by convection and radiation) as they do in the actual, non-uniform environment.
Equivalent transformation – It is a mathematical or physical modification which simplifies a complex system while preserving its external behaviour or key properties. By converting a rigid system into an easier-to-analyze form, engineers can readily solve for forces, stresses, or circuit responses.
Equivalent vessel – It is a conceptual or mathematical stand-in used to simplify complex piping, hydraulic, or structural systems. It represents a theoretical container or component which produces the exact same flow resistance, pressure drop, or dynamic response as the original, more complex system.
Equivalent voltage – It is the theoretical open-circuit voltage present at a specific set of terminals in an electrical network. It represents the single ideal voltage source which, when combined with a series equivalent resistance, perfectly mimics the electrical behaviour of a complex, linear circuit.
Equivalent weight – It is the mass of a substance which exactly reacts with, displaces, or is equivalent to a fixed standard (typically 1.008 grams) of hydrogen, 8 grams of oxygen, or 1 mole of electrons).
Erase operation – It typically refers to the process of resetting physical media (like flash memory or magnetic disks) to a baseline state, or a surface-finishing process used to remove surface asperities, defects, and excess material to achieve required dimensional or aesthetic properties.
Erbium (Er) – It is a chemical element having atomic number 68. It is a soft, silvery-white rare-earth metal in the lanthanide series. Natural erbium is always found in chemical combination with other elements. Mainly used in technology, erbium-doped fibres amplify signals in optical communications, while its pink-coloured oxide is used as a u in glass, and ceramics.
Erbium-doped fibre – It is a specialized optical fibre used as a light amplification medium. By integrating rare-earth erbium ions into its silica core, the fibre amplifies optical signals directly (without converting them to electricity) when stimulated by a pump laser. This technology is the foundation of erbium-doped fibre amplifiers (EDFA), which are critical for high-speed, long-haul telecommunications.
Erbium-doped fibre amplifier – It is a device which directly boosts the intensity of weak optical signals without converting them into electrical data. By using a silica optical fibre infused with erbium ions, it uses pump lasers to amplify light precisely within the low-loss (1,550 nano-meters) communication band.
Erbium-doped yttrium aluminium garnet (Er:YAG laser) – It is a type of solid-state laser which uses a synthetic crystal (Er:Y3Al5O12) as the gain medium, typically emitting light at a wavelength of 2,940 nano-meters in the infrared spectrum. It is highly absorbed by water.
Erbium fibre – It is normally known as erbium-doped fibre (EDF). It is an optical fibre core infused with erbium ions. When pumped with a specific laser diode, it acts as an active gain medium used to amplify weak optical signals without first converting them into electrical signals.
Erbium ion (Er3+) – It is a positively charged rare-earth metal atom with a unique ‘4f’ inner electron shell which produces distinct optical and magnetic properties. It is mainly utilized to amplify light signals in fibre-optic communications and is an emerging hardware building block for quantum networks.
Erection – It means all the on-site erection and installation activities, as applicable, including fabrication, assembly, construction, alignment, leveling, installation, interfacing, piping, welding, preheating, annealing, insulating, lagging, painting, grouting, fastening and anchoring, clearing, checking, oil filling and treating, adjusting, and quality testing.
Erection and maintenance loads – Erection and maintenance loads are temporary loads from equipment, such as cranes and fork-lifts, needed for installing or dismantling equipment components during erection or maintenance. Erection loads are normally furnished in the manufacturer’s foundation load drawing and are to be used in conjunction with other specified dead, live, and environmental loads. Maintenance loads occur any time the equipment is being drained, cleaned, repaired, and realigned or when the components are being removed or replaced. Loads can result from maintenance equipment, davits, and hoists. Environmental loads, such as full wind and earth-quake, are not normally assumed to act with maintenance loads, which normally occur for only a relatively short duration.
Erection contract – It describes a contract under which an engineering contractor undertakes erection activities at site.
Erection drawing – An erection drawing provides information for properly positioning and installing items relative to their supporting structure and adjacent items. This information includes dimensional data, hardware descriptions, and general configuration information for the installation site. The erection drawing is prepared to provide detailed installation information for (i) functionally related items (such as a control system, electrical system, or hydraulic system) which cannot be effectively shown on an assembly drawing of the item to which it belongs, or (ii) a part or assembly which is so large or complex that the major assembly drawing cannot accommodate all relevant data. An erection drawing normally includes (i) overall and principal dimensions in sufficient detail to establish space requirements for installation, operation, and servicing including clearances for opening of doors, removal of plug-in units and travel or rotation of any moving parts (including the centres of rotation, angles of elevation and depression), (ii) interface mounting and mating information (e.g. locating dimensions for attaching hardware), (iii) interfaces for pipe and cable attachments, (iv) information necessary for preparation of foundation plans including mounting details, (v) references to interconnecting and cabling data and to associated lists, (vi) identification of and requirements for installation items not included in the parts list of the using assembly drawing, (vii) reference to the assembly drawing of the major item being installed, (viii) a parts list specifying the items to be installed thus establishing item identification for a work package, and (ix) supporting structure or associated items which are not included in the installed items.
Erection equipment – It refers to the specialized heavy machinery and temporary tools used to lift, position, and assemble structural components (e.g., steel beams, girders) or industrial machinery (e.g., turbines, conveyors) on-site.
Ergodic capacity – It is the theoretical maximum average data rate which can be reliably transmitted over a time-varying (fading) channel, where the channel’s statistical properties remain constant over time. It is the statistical expectation or mean of instantaneous capacities over all possible fading states. Unlike static channels where capacity is calculated for a fixed signal-to-noise ratio (SNR), a time-varying channel has a fluctuating capacity. To use ergodic capacity, the channel is to be ergodic, meaning the time average of a single fading sequence is identical to its statistical average over all possible fading states.
Ergodic hypothesis – It is the assumption that monitoring a stochastic system over a long time is equivalent to statistically sampling several independent realizations of the system, particularly when only a single instance can be observed. This hypothesis is important in fields like statistical physics, thermodynamics, and economics and is rigorously true only in the infinite volume limit.
Ergodicity – It means that the time average of a single system’s trajectory equals its ensemble average (the average of several identical systems observed at the same moment). If a process is ergodic, watching one system over a long period reveals all possible statistical behaviours of the entire system.
Ergodic process – It is a stochastic system where the time average of a single trajectory equals the ensemble average of all possible trajectories. If a system is ergodic, people can accurately predict its long-term behaviour by observing one instance over a long period.
Ergodic rate – It is the maximum, theoretically achievable data rate (in bits per second per hertz) over a fading channel, assuming the channel state varies sufficiently over time. It relies on the statistical principle of ergodicity, where the long-time average of a signal equals its ensemble average (i.e., looking at several different channel states at once).
Ergonomic design – It is the scientific discipline of tailoring products, systems, and work-spaces to fit human capabilities and limitations. Its main operation is to ‘fit the job to the person’ rather than forcing the user to adapt to the equipment, ultimately reducing injury risks, physical fatigue, and operational errors.
Ergonomic intervention – It is the process of modifying or redesigning a work environment, task, or tool to fit the physical, cognitive, and organizational capabilities of the user. Its main operation is to prevent injuries and optimize human well-being and overall system performance. These interventions normally operate across three main approaches namely physical interventions, organizational Interventions, and cognitive and training interventions.
Ergonomic manufacturing – It refers to the design of work environments, tools, and processes to fit the physical and cognitive capabilities of human workers. Its main goal is to optimize efficiency and productivity by minimizing fatigue and reducing the risk of musculoskeletal disorders.
Ergonomic optimization – It is the ongoing study and implementation of design principles to improve worker safety, comfort, and efficiency within conveyor systems and work environments, needing continual assessments and improvements.
Ergonomics – It is also known as human factors or human factors engineering (HFE). It is the application of psychological and physiological principles to the engineering and design of products, processes, and systems. Main objectives of ergonomics are to reduce human error, increase productivity and system availability, and improve safety, health and comfort with a specific focus on the interaction between the human and equipment.
Ergonomics management – It is the systematic process of designing and arranging a work-place to fit the physical and cognitive capabilities of the workers. Its main operational goal is to prevent injuries like back pain, while improving overall productivity and efficiency.
Ergonomic system – It is a design and operational framework which adapts tools, environments, and tasks to fit human capabilities and limitations, rather than forcing humans to adapt. The main goal is to optimize human well-being and overall system performance.
Ergun equation – It is a mathematical relationship used to calculate pressure losses through packed beds, combining a viscous term from the Kozeny-Carman equation and an inertial term from the Burke-Plummer equation to address varying porosity conditions.
Erichsen cupping test – Erichsen test is conducted as per International Organization for Standardization standard ISO 20482. It involves pressing a spherical punch into clamped sheet metal until a crack appears, measuring the depth of the resulting cup to gauge formability. It is a quick and standardized mechanical testing method used to determine the stretch-forming capacity (ductility) of metal sheets and strips. It is a deep-drawing test which is used to determine the stretch-forming capacity of sheet metals, which have a thickness of 0.1 millimeters to 2 millimeters and a width of 90 millimeters or more. This cupping test is used to assess the ductility of sheet metal.
Erichsen test – It is a standardized, quick industrial method for determining the stretch-forming capacity (formability) and ductility of metallic sheets and strips. It involves pressing a spherical punch into a clamped sheet until a crack appears, with the depth of the resulting cup (in millimeter) defining the Erichsen number (Ie).
Eriochrome black-T – It is a complexometric indicator, a type of dye, used in titration to determine the concentration of metal ions, particularly in water hardness testing. It is an azo dye, known for its colour change in the presence of metal ions.
Eroding polymers – These refer to polymeric materials which undergo a process of erosion, which involves the gradual removal of material because of the factors such as diffusion and degradation, frequently occurring in a complex interplay of mechanisms. This process is modelled through different approaches which account for the dynamics of degradation and the release of low-molecular-weight compounds.
Erosion – It is the loss of material from a solid surface because of the relative motion in contact with a fluid which contains solid particles. Erosion in which the relative motion of particles is nearly parallel to the solid surface is called abrasive erosion. Erosion in which the relative motion of the solid particles is nearly normal to the solid surface is called impingement erosion or impact erosion. Erosion is also the progressive loss of original material from a solid surface because of the mechanical interaction between that surface and a fluid, a multicomponent fluid, and impinging liquid, or solid particles. It is also the loss of material from the surface of an electrical contact because of an electrical discharge (arcing).
Erosion, brazing – It is a condition caused by dissolution of the base metal by molten filler metal resulting in a reduction in the thickness of the base metal.
Erosion control – It refers to practices and techniques used to prevent or minimize the loss of soil because of the natural forces like wind and water. It involves stabilizing the soil, managing runoff, and protecting vulnerable areas from erosion, ultimately conserving the environment and reducing potential damage.
Erosion-corrosion – It is a conjoint action involving corrosion and erosion in the presence of a moving corrosive fluid, leading to the accelerated loss of material.
Erosion damage – It is the gradual wearing away, fracturing, or deterioration of a solid material caused by continuous mechanical or physical force (such as wind, water, or abrasive particles). It results in surface roughening, cracking, or loss of material, distinctly differing from chemical corrosion.
Erosion model – It is a mathematical or computer simulation used to predict how and where earthen materials or physical surfaces wear away and transport because of the natural forces like wind or water, or through mechanical wear in industrial equipment.
Erosion problem – It is the mechanical wear, deterioration, or progressive loss of a material (soil, rock, or metal) caused by the impact or friction of fluids, solid particles, or gas flows. Unlike chemical corrosion, erosion is a strictly physical phenomenon which damages both natural landscapes and industrial equipment.
Erosion process – It is defined as the wear produced on materials due to the impact of solid particles or liquid droplets, resulting in continuous or rapid material loss and potentially creating smooth, scoured, or rippled surfaces. This process can be exacerbated by corrosive attacks that remove protective films.
Erosion rate – It is a determination of the rate of loss of material (erosion) with exposure duration. In certain contexts, it is given by the slope of the cumulative erosion-time curve.
Erosion rate-time curve – It is a graph of instantaneous erosion rate against exposure duration, normally got by numerical or graphical differentiation of the cumulative erosion-time curve.
Erosion, refractories – It is the wearing-away of refractory surfaces by the washing action of moving liquids. It consists of surface wear of a refractory caused by the mechanical action of a fluid, whether or not it contains solid material.
Erosion resistance – It is a material’s or surface’s ability to withstand incremental material loss caused by mechanical forces—such as friction, high-speed fluid impact, or abrasive solid particles. It is a critical property for maintaining structural integrity and preventing degradation in harsh environments.
Erosion scab – It is a casting defect in metal casting where molten metal erodes (washes away) a part of the sand mould, resulting in a rough, uneven, and raised protrusion on the surface of the finished casting. It is a type of expansion defect, frequently appearing as a thin, flaky, or crusty piece of metal, normally separated from the main casting by a thin layer of sand.
Erosion wear – – It is also called erosive wear. It is (i) loss of material from a solid surface because of the relative motion in contact with a fluid which contains solid particles. Erosion in which the relative motion of particles is nearly parallel to the solid surface is called abrasive erosion. Erosion in which the relative motion of the solid particles is nearly normal to the solid surface is called impingement erosion or impact erosion, (ii) progressive loss of original material from a solid surface due to mechanical interaction between that surface and a fluid, a multi-component fluid, and impinging liquid, or solid particles, and (iii) loss of material from the surface of an electrical contact because of an electrical discharge (arcing). Because of the broad scope of this term, it is desired that it normally be qualified to indicate the relevant mechanism or context, e.g., impingement erosion. abrasive erosion, and so forth.
Erosive particles – These are also called erodents. are hard solid particles or liquid droplets which impact a material surface at high speeds, causing progressive material loss. This process, known as erosive wear, is common in industrial equipment, wind turbines, and aerospace components subjected to high-velocity fluid or gas flows.
Erosive wear – It is the progressive loss of material from a solid surface because of the mechanical impact of high-velocity fluids, gases, or entrained solid particles. It is a form of mechanical surface degradation common in components exposed to flow, such as piping, pumps, and turbine blades.
Erosive wear resistance – It is the ability of a material to withstand progressive surface degradation caused by the repeated, high-velocity impact of solid particles or liquid droplets. It dictates a material’s lifespan in harsh environments like fluid piping, pumps, and turbine blades.
Erosivity – It is the characteristic of a collection of particles, liquid stream, or a slurry that expresses its tendency to cause erosive wear when forced against a solid surface under relative motion.
Erroneous sample – It is a dataset, sample, or observation which deviates from the true, expected, or accurate state of the target population. These samples lead to invalid results.
Error – It is a mistake or error of judgement leading to action resulting in an accident and its subsequent effects. In the process control systems, error is defined as the difference between set point and process variable and is given by the equation ‘error = set point – process variable’. In a statistical interpretation, the word ‘error’ is used to denote the difference between an observed value and its ‘expected’ value as predicted or explained by a model. In addition, errors occur in data collection, sometimes resulting in outlying observations. Finally, type I and type II errors refer to specific interpretive errors made when analyzing the results of hypothesis tests.
Error amplifier – It is a core control-system component which calculates the difference between an actual system output (like voltage or current) and a target reference signal, and amplifies this discrepancy into a control signal. It serves as the decision-making brain of the feedback loop to maintain stability.
Error bound – It defines the maximum possible difference between an approximated, calculated, or measured value and the true value. It establishes an upper limit to uncertainty, ensuring that numerical simulations, control system models, or physical measurements remain within safe, predictable operating thresholds.
Error cancellation – It refers to active techniques used to actively offset, eliminate, or suppress unwanted disturbances, noise, or computational errors. Depending on the engineering discipline, it can mean canceling physical audio / vibration noise, mitigating computational floating-point flaws, or correcting quantum hardware errors.
Error coefficients – These are also called error constants. These are numerical parameters used to measure the performance and steady-state accuracy of a system. They define how effectively a system tracks a desired input, where higher coefficients indicate a smaller steady-state error.
Error concealment – It is a technique used in signal and data processing to hide or mitigate the effects of missing or corrupted data (e.g., packet loss) at the receiver end. Rather than halting the system, it estimates and reconstructs the lost information to maintain an acceptable quality of service.
Error convergence – It refers to the discrepancies between a fully converged solution and a solution which has not yet achieved convergence in iterative computational methods. It arises when the iterative process is stopped prematurely or when excessive convergence tolerances are applied, leading to solutions which can still be considerably distant from the final converged state.
Error correcting capability – It refers to a system’s or code’s ability to automatically detect and reconstruct corrupted data back to its original state without needing a retransmission. It relies on adding redundant bits during encoding to identify and fix transmission or storage faults caused by signal noise.
Error-correcting code – This is a technique used to detect and automatically fix data errors which occur during transmission or storage. By adding structured, redundant bits to the original message, error-correcting code (ECC) allows the receiving system to isolate and reconstruct the correct data without needing a retransmission from the sender.
Error correction – It is the process of detecting and reconstructing corrupted or distorted data into its original, accurate form. It ensures systems, like telecommunications, computer storage, and micro-processors, maintain data integrity and reliable performance despite interference, noise, or hardware faults.
Error correction capability – It defines a system’s ability to automatically detect and fix corrupted, degraded, or lost data during storage or transmission without needing a retransmission. It ensures structural and informational integrity in physical systems, networks, and storage media.
Error covariance – It is a mathematical measure of uncertainty. It defines how the errors in different estimated variables or measurements relate to one another, typically expressed as a covariance matrix where diagonal elements represent individual variances and off-diagonal elements show error correlations. In engineering fields like robotics, control systems, and signal processing, this concept is important for understanding the reliability of state estimates.
Error covariance matrix – It is a square matrix which quantifies the uncertainty and statistical correlation between errors in a set of estimated variables. It defines how far off estimated values are from true values, including the directional dependencies of these deviations.
Error decay – It refers to the rate at which the difference between a desired (target) state and an actual (observed) state diminishes over time, iterations, or distance. It is an important performance metric used to evaluate stability, convergence, and accuracy across multiple disciplines.
Error diffusion – It is a digital halftoning technique which converts multi-level images (like continuous-tone grayscale) into binary or limited-palette images. It works by calculating the quantization error, the difference between the original pixel value and the approximated output, and distributing which exact error to neighbouring, unprocessed pixels to preserve local average intensity.
Error dynamics – It refers to the mathematical and physical representation of how the difference between a desired state (or reference input) and an actual system output changes over time. It models how errors evolve, propagate, and are corrected by control inputs within time-varying systems.
Error estimation procedure – It is a systematic methodology to quantify the uncertainty, deviation, or numerical inaccuracy in a measurement, experimental result, or computational model (such as finite element analysis). It ensures the reliability, safety, and validity of engineering designs.
Error estimator -It is a mathematical or algorithmic tool used to quantify the difference between a computed (or approximated) value and the true value of an unknown parameter. It evaluates model accuracy, guides system design optimizations, and minimizes uncertainties in practical applications.
Error function – It is a special, non-elementary mathematical function which represents the integral of the normal (Gaussian) distribution. It is heavily used to model probability, diffusion, and heat transfer.
Error message – It is a notification or system communication indicating an operation failed, a fault occurred, or an unintended event happened. It serves to inform users or developers of the specific issue and provide actionable steps to resolve or recover from it.
Error modelling – It is the process of mathematically identifying, quantifying, and predicting the inaccuracies and uncertainties within a system or model. It distinguishes between errors (measurable, recognizable discrepancies) and uncertainties (unknowns because of the lack of knowledge) to ensure system reliability and accuracy.
Error of measurement – It is the result of a measurement minus a true value of the measurement. It can also be expressed as a percentage.
Error rate – It is the frequency at which a system, process, or component produces incorrect, invalid, or failed outcomes. It is an important metric for quantifying reliability, accuracy, and performance, normally calculated by dividing defective units or failed operations by the total number of attempts.
Error rate prediction – It is a forecast of the possibility of error based on statistical data.
Error signal – It is the difference between a system’s desired reference input (or set-point) and its actual measured output. It serves as the core feed-back mechanism which drives controllers to self-correct and minimize discrepancies.
Error term – It is a variable in a mathematical or statistical model which accounts for the deviation between the model’s predicted values and real-world reality. It represents the effects of omitted variables, inherent randomness, or unpredictable physical factors.
Error tolerance – It refers to a system’s ability to function safely and acceptably despite variations, defects, or human mistakes. It ensures that minor errors do not cause catastrophic system failure, prioritizing continuous operation or graceful performance degradation.
Error vector – It is the geometric difference in the complex In-phase / quadrature (I/Q) plane between a measured actual signal symbol and its corresponding ideal reference symbol. It serves as an important tool to identify, quantify, and trouble-shoot cumulative distortions within hardware systems.
Error voltage – It is the difference between an expected (or reference) voltage and the actual measured voltage. It acts as a corrective signal in closed-loop systems, and represents a deviation or inaccuracy in measurement systems.
Escape peak – It is an artifact observed in X-ray analysis. It is manifested as a peak at energy 1.74 kilo-electron volt (the silicon K-alpha peak) less than the major line detected. Escape peaks can be avoided by increasing the accelerating voltage.
Escape velocity – It refers to the rate at which gas bubbles or vapour pores rise to the surface of a liquid metal pool. It is the critical speed a bubble is required to achieve to break free from the melt before the metal solidifies, which dictates the metal’s final porosity and density. Escape velocity is also the minimum speed needed for an object to break free from a celestial body’s gravitational pull and escape into space without any further propulsion.
Eshelby problem – It is a fundamental concept in continuum mechanics which defines the elastic strain and stress fields within an infinitely extended elastic material caused by a localized eigenstrain (transformation strain) in an ellipsoidal sub-region (the inclusion).
Eshelby tensor – It is a fourth-rank tensor in solid mechanics which relates the eigenstrain (inelastic stress-free transformation strain) of an ellipsoidal inclusion to the resulting constrained strain within it. It is a fundamental concept in micro-mechanics, describing how stress is distributed within an inhomogeneity.
ESR-VAR remelting process – In this process, the ESR (electroslag remelting) operation produces a clean, sound electrode for subsequent remelting. The improved electrode quality facilitates control in the VAR (vacuum arc remelting) operation, producing material with a higher assurance of freedom from alloy-rich segregation (in very large ingot) and a reduced frequency of white spots for all ingot sizes.
Essential boundary condition – It is also known as a Dirichlet condition. It is a constraint which directly specifies the fixed value of a main variable (such as displacement, temperature, or voltage) at the boundary of a domain. Essential boundary conditions are fundamental since they are strictly needed to make the governing differential equations solvable and to yield a unique solution.
Essential node – It is also called extraordinary node. It is a junction point in an electrical circuit where three or more circuit elements (branches) connect. Unlike standard nodes which only connect two components, essential nodes are the main focus for applying Kirchhoff’s current law (KCL) and performing nodal analysis.
Essential requirement – It is a core, indispensable feature or condition a system is required to have to function and meet its fundamental goals. It captures the absolute necessities which cannot be altered or removed without compromising the product’s very purpose.
Essential service water system – This system circulates the water which cools the plant’s heat exchangers and other components before dissipating the heat into the environment. Since this includes cooling the systems which remove decay heat from both the primary system and the spent fuel rod cooling ponds, the essential service water system is a safety-critical system. Since the water is frequently drawn from an adjacent river, the sea, or other large body of water, the system can be fouled by seaweed, marine organisms, oil pollution, ice and debris. In locations without a large body of water in which to dissipate the heat, water is recirculated through a cooling tower.
Essential variable – It is a process parameter which directly impacts the structural integrity, mechanical properties (such as tensile strength or ductility), or metallurgical structure of a finished product. If any essential variable is changed outside its pre-approved or qualified range, in manufacturing, fabrication, and welding, the entire procedure or operator is required to undergo formal re-qualification (such as destructive testing or writing a new procedure qualification record) to prove the new parameters still meet industry safety codes.
Ester – It is a class of organic and inorganic compounds derived from the reaction of an acid with an alcohol, in which at least one hydroxyl group (–OH) is replaced by an alkoxy group (–O–). Esters have the general formula RCOOR′, where R and R’ represent any alkyl or aryl group.
Ester amide – It refers to a copolymer or hybrid linkage containing both ester and amide functional groups. It merges the bio-degradability and hydrolytic cleavage properties of esters with the structural rigidity, thermal stability, and high tensile strength of amides.
Ester bond – It is also called ester linkage. It is a chemical bond formed by the condensation reaction (esterification) of a carboxylic acid and an alcohol, resulting in the elimination of a water molecule. The general chemical formula for this functional group is R-COOR’.
Ester content – It refers to the exact percentage of ester molecules present in a given chemical product or fuel mixture. It is an important quality control metric, very frequently measured in synthetic lubricants and bio-fuels to ensure purity, oxidative stability, and regulatory compliance.
Ester linkage – It is a covalent chemical bond (-COO-) formed through a condensation reaction between a carboxylic acid and an alcohol. These bonds are foundational for synthesizing polyesters, e.g., poly-ethylene terephthalate (PET), bio-plastics, and formulating durable coatings.
Ester urethane urea – It is typically categorized as a poly(ester urethane) urea or PEUU. It is a segmented block copolymer renowned for its elasticity and tunable mechanical properties. It is synthesized by reacting a polyester polyol with a diisocyanate and chain-extended using diamines.
Estimate – It is an approximate calculation, judgment, or educated guess regarding the size, cost, value, or quantity of something based on available information. It acts as a projection rather than an exact measurement, frequently used in the organization to determine potential project costs or in statistics to gauge population parameters.
Estimated budget – It is a preliminary calculation of anticipated income and expenditures for a future period, acting as a financial guideline. It serves as a, roughly, calculated plan rather than a final commitment, allowing organizations to map out resources, allocate funds for projects, and set performance targets.
Estimated coefficient – It represents the calculated or approximated numerical value of a parameter within a mathematical model. It quantifies the relationship between variables (e.g., how a change in input affects output) or reflects a physical property of a system which cannot be measured directly.
Estimated consumption – It is an approximated calculation of raw materials, utilities, or services used by a process when actual, real-time measurement is unavailable or impossible. It is normally determined using historical data, such as average consumption over a prior 3-month or 12-month period.
Estimated cost – It is a forecasted, pre-production or pre-construction calculation of the projected expenditures for a project or manufactured product, including materials, labour, and overhead. It serves as an important baseline for budgeting, evaluating project feasibility, and establishing final, competitive, or contractual pricing.
Estimated distance – It is a calculated or predicted value of physical separation derived from mathematical models, sensor data, or statistical approximations, rather than direct physical measurement. It is typically used in system design, navigation, and quality control when direct measurement is impractical.
Estimated production – It is a forecasted quantity of goods, energy, or resources expected to be generated over a specific future period, frequently based on historical data, capacity, or engineering projections. It serves as a key metric for planning, valuation, and contractual obligations in industries like energy, mining, and manufacturing.
Estimated quality – It is the assessed value, excellence, or fitness for purpose of a product or service based on customer perceptions, standards, or anticipated performance, frequently measuring how well it meets requirements. It combines tangible metrics (performance, durability) with subjective perceptions (aesthetics, brand reputation).
Estimated results – These are approximate values, calculations, or projections regarding unknown quantities, derived from available data, samples, or projections. They represent educated guesses, such as budgeted expenses, expected software outputs, or calculated production metrics, frequently used when exact, instantaneous, or actual data is impossible or too expensive to get.
Estimated risk – It is the quantitative or qualitative measurement of the likelihood of an unwanted event combined with the magnitude of its potential consequences. It is calculated to prioritize hazards, allocate safety resources, and guide decision-making.
Estimated strain – It is the measure of deformation experienced by a material, frequently determined through the analysis of strain markers which show known pre-strain geometric details or distributions. It reflects the finite strain state of a rock, which is necessary for understanding its deformation history and tectonic structures.
Estimated ultimate recovery – It is the total volume of hydro-carbons (oil and gas) estimated to be economically recoverable from a well, reservoir, or field over its entire productive life-span. Estimated ultimate recovery (EUR) is the sum of all oil and gas already produced up to a specific date, plus the volumes projected to be produced in the future.
Estimated utility – It is a quantifiable metric representing the desirability of a design, system, or process. It combines the probabilities of different outcomes with the subjective value of those outcomes to help engineers optimize choices under uncertainty.
Estimate methods – These are techniques for calculating the quantities of different work items. These estimation techniques enable a person to plan for resource allocation, provide better forecasts, and budget the funds and resources needed for project success more accurately.
Estimating software – It refers to specialized tools designed to facilitate the calculation of manufacturing costs through different methods, including parametric and feature-based approaches, enabling users to produce accurate cost estimates based on part features and historical data.
Estimation – Estimation is the process by which sample data are used to indicate the value of an unknown quantity in a population. The results of estimation can be expressed as a single value, known as a point estimate. It is normal to also give a measure of precision of the estimate. This is called the standard error of the estimate. A range of values, known as a confidence interval can also be given.
Estimation criterion – It is a defined mathematical rule or operational standard used to measure, evaluate, and optimize system parameters (e.g., error minimization, signal processing) or project outcomes (e.g., cost, scheduling). It dictates exactly how an ‘ideal’ or ’acceptable’ estimate is calculated.
Estimation error dynamic – It is a mathematical model which describes how the difference between a system’s true state and its estimated state evolves over time. It is used to guarantee that algorithms like observers or filters accurately converge and maintain stability.
Estimation procedure – It is a systematic process used to approximate costs, effort, timelines, or technical parameters before a project begins. It relies on data, mathematical formulas, historical benchmarks, and expert judgment to establish reliable targets for budgeting, resource allocation, and project feasibility. The estimation procedure typically follows a structured, phased methodology to ensure accuracy and minimize risk.
Estimation scheme – It refers to the structured methodology, mathematical framework, or set of procedures used to predict a project’s future outcomes (such as costs, timelines, or resource requirements) or to calculate unknown physical / system variables from incomplete data.
Estimator – An estimator is a quantity calculated from the sample data, which is used to give information about an unknown quantity (normally a parameter) in the population. For example, the sample mean is an estimator of the population mean. Estimators of population parameters are sometimes distinguished from the true (but unknown) population value, by using the symbol ‘hat’.
Estuaries – These are areas where freshwater from rivers meets and mixes with saltwater from the sea, frequently characterized by substantial sediment transport capabilities influenced by varying freshwater discharges.
Eta carbide – It is a hard, brittle, sub-stoichiometric phase which forms in cemented carbides (such as tungsten carbide-cobalt (WC-Co), and certain steels when there is a deficiency of carbon. It is normally described as a tertiary carbide with the chemical formula M6C or M12C, where ‘M’ represents transition metals such as tungsten, cobalt, iron, or nickel.
Eta layer – It is the fourth outer layer of the galvanized coating solely comprised of zinc.
Etalon – It is an optical device consisting of two parallel, partially reflecting surfaces, such as glass plates, separated by a fixed distance. It acts as a high-resolution interferometer or narrow-band filter which uses multiple-beam interference to measure wave-lengths, analyze spectral lines, and tune laser frequencies in optics, spectroscopy, and telecommunications.
Eta phase – It is normally designated as Ni3Ti or sometimes Ni3(Ti, Al, Nb). It is a stable intermetallic phase which forms in nickel (Ni) based superalloys at high temperatures, typically between 750 deg C and 900 deg C. While it can serve as a grain-size control agent during hot working, its accumulation at grain boundaries is frequently considered deleterious to the long-term creep strength and ductility of superalloys.
Eta, statistics – It is an index which indicates the degree of a curvilinear relationship.
Etch – It is a roughened surface produced by chemical or electro-chemical means. It also means to dissolve unevenly a part of the surface of a metal.
Etch adhesive – It is mainly defined as a resin bonding agent which needs a preliminary acid-etching phase (using phosphoric acid) to create micro-mechanical retention between a substrate and a restorative material.
Etchant – It is a chemical solution used to etch a metal to reveal structural details. It is also a solution used to remove, by chemical reaction, the unwanted portion of material from a printed circuit board. It also means hydro-fluoric acid or other agent used to attack the surface of glass for marking or decoration.
Etch cleaning – It consists of removing soil by dissolving away some of the underlying metal.
Etch cracks – These are shallow cracks in hardened steel containing high residual surface stresses, produced by etching in an embrittling acid.
Etch depth – It refers to the vertical distance or the extent to which material is intentionally removed from a substrate’s surface during the etching process. It is the difference in height between the original, unetched surface and the bottom of the newly formed trench, cavity, or channel.
Etch figures – These are the characteristic markings produced on crystal surfaces by chemical attack, normally having facets parallel to low-index crystallographic planes.
Etching – It is subjecting the surface of a metal to preferential chemical or electrolytic attack in order to reveal structural details for metallographic examination. It is also chemically or electro-chemically removing tenacious films from a metal surface to condition the surface for a subsequent treatment, such as painting or electro-plating.
Etching, pitting -It is the localized attack of metal surfaces. Controlled etching of metals improves the adhesion of organic coatings. By contrast, uncontrolled etching of metals by an acid can cause damage by weakening the crystal structure.
Etching process – It is a micro-fabrication / nano-fabrication technique which removes material to create complex 3D micro-structures, utilizing methods such as wet etching and dry etching, with the latter including processes like reactive ion etching (RIE) which allow for high-resolution, anisotropic material removal.
Etching treatment – It is a controlled material-removal process used to create intricate micro-features on a substrate or to alter surface properties for better adhesion. It is widely used across semi-conductor manufacturing, printed circuit board (PCB) fabrication, and metallurgical surface treatment.
Etch pits – It is the localized corrosion attack at the microscopic scale. It is typically seen on a polished and etched metallographic specimen. Etch pits typically have recognizable, simple geometric shape (square, rectangle, and triangle) and hence reveal, in a qualitative way, the orientation of a grain. It is also a conjoint action involving corrosion and erosion in the presence of a moving corrosive fluid, leading to the accelerated loss of material.
Etch primer – It is a type of pre-treatment coating used to promote adhesion, particularly on non-ferrous metals, while providing temporary protection to ferrous metals. It is typically based on poly-vinyl butyral resins and is to be overcoated with a fully pigmented primer.
Etch priming – It is a chemical and mechanical surface preparation technique. It applies a specialized coating, frequently containing a mild acid like phosphoric acid and a synthetic resin, to bare metal. Some galvanized coating primers contain acid etching components to improve adhesion. These are application critical products which needs experience in their application.
Etch rate – It is the speed at which a material is removed from a substrate during an etching process. It is a fundamental metric in semi-conductor manufacturing, dictating the precision, quality, and manufacturing throughput of micro-fabrication techniques.
Etch rinsing – It is pouring etchant over a tilted surface until the desired degree of attack is achieved. It is used for etchants with severe gas formation.
Etch test – It is also called macro-etch test. It is a destructive metallurgical examination which involves cutting, polishing, and chemically treating a metal sample normally a weld cross-section, to reveal its internal structure, including grain structure, porosity, cracks, and penetration depth. It highlights disparities in material composition, such as between the base metal and heat-affected zone (HAZ), to verify quality.
E-textiles – These are also called electronic textiles. These are fabrics which integrate electronic components and conductive materials directly into their structure. These fabrics serve as ‘soft circuits’ which blend electrical functionality with mechanical flexibility, solving electro-mechanical problems in wearables, automotive interiors, and robotics where traditional rigid circuit boards might fail.
Ethane – It is a naturally occurring organic chemical compound with chemical formula C2H6. At standard temperature and pressure, ethane is a colourless, odourless gas. Like several hydrocarbons, ethane is isolated on an industrial scale from natural gas and as a petrochemical by-product of petroleum refining. Its main use is as feedstock for ethylene production. The ethyl group is formally, although rarely practically, derived from ethane.
Ethanol – It is a clear, volatile, and flammable organic compound with the chemical formula CH3CH2OH. It is a primary alcohol which is widely used as a renewable bio-fuel, a chemical solvent, and an octane-improving additive in automotive fuels.
Ethanol bio-refinery – It is a facility which processes biomass to produce ethanol through methods like fermentation and distillation, while also generating value-added coproducts like bio-fuels.
Ethanol concentration – It refers to the quantitative measurement of ethanol (C2H5OH) relative to other substances (like water, impurities, or gasoline) in a mixture. It is typically expressed in weight percent, volume percent, or mole fraction.
Ethanol fuel – It is a clear, renewable alcohol (C2H5OH) derived from biomass through fermentation and distillation. It serves as a combustible alternative to petroleum, valued for its high-octane rating and cleaner combustion properties.
Ethanol industry – It is the industrial sector dedicated to producing ethyl alcohol (C2H5OH) on a massive scale, mainly as a renewable fuel additive, industrial solvent, and chemical feedstock. It relies heavily on chemical and process engineering to convert biomass efficiently into high-purity alcohol.
Ethanol production – It is the systematic process of converting biological feedstocks into high-purity ethyl alcohol (C2H5OH) through fermentation, followed by energy-intensive separation and dehydration techniques.
Ethanol production process – It is an industrial method which converts plant-based biomass or organic feedstocks into ethyl alcohol through grinding, enzymatic hydrolysis, fermentation, and distillation. The main goal is to break down starches into simple fermentable sugars, which are then processed by yeast into fuel-grade or industrial ethanol.
Ethanol purification – It is the process of recovering and concentrating bio-ethanol from a dilute fermentation broth to achieve high-purity levels (up to 99+ %). It mainly relies on separating ethanol from water and organic impurities through distillation, rectification, and dehydration techniques based on boiling point and volatility differences.
Ether – It is a class of organic compounds and a functional group containing an oxygen atom connected to two alkyl or aryl groups, which can be the same or different. Ethers have the general formula R–O–R′, where R and R′ represent the alkyl or aryl groups.
Etherification – It is a chemical treatment used to modify the fibre surface by grafting bi-functional monomers capable of making the reaction easier between polymer chains and fibres. This treatment chemically alters the cellulose fibres on the surface to promote other treatments such as silane, esterification, acetylation, and benzoylation. These modifications have no substantial influence on the native structure of natural fibres and their morphology.
Ethernet controller – It is a hardware component which manages the transmission and reception of data over Ethernet networks, supporting different features such as both half-duplex and full-duplex operation, automatic polarity detection, and collision management.
Ethernet frame – It is the foundational data link layer (layer 2) protocol data unit (PDU) used to encapsulate and transmit data across local area networks. Standardized by the Institute of Electrical and Electronics Engineers standard IEEE 802.3 specifications, it structures upper-layer traffic into discrete blocks to guarantee hardware-level delivery, synchronization, and error detection.
Ethernet interface – It is the hardware, software, and protocol boundary which connects a computing device to a local area network (LAN). It defines the exact physical, electrical, and logical specifications (standardized under Institute of Electrical and Electronics Engineers standard IEEE 802.3) needed to transmit data packets between systems.
Ethernet protocol – It is defined as a communication protocol that operates at layer 2 of the open system intercommunication (OSI) seven-layer model, playing a crucial role in data networks by facilitating the transmission of data packets between devices. It has evolved from shared coaxial cable to switch-based protocols, incorporating technologies like ‘spanning tree protocol’ and virtual local area network (VLAN) for reliability and segmentation of broadcast domains.
Ether urethane – It frequently called poly-ether poly-urethane. It is a highly versatile elastomer or foam formed by reacting isocyanates with poly-ether polyols. It is widely used for its superior hydrolytic stability (moisture resistance) and flexibility in low temperatures.
Ethoxylate – It is a non-ionic surfactant produced through the ethoxylation of compounds containing free hydroxyl groups, resulting in a polymer chain of ethylene oxide (EO) which influences its properties and performance in different applications, particularly in the formulation of micro-emulsions.
Ethyl-benzene – It is a colourless, highly flammable liquid hydrocarbon with a gasoline-like odour, having the chemical formula C8H10. It is an important intermediate in the production of styrene, which is a precursor to the common plastic polystyrene. It is also naturally present in petroleum products and is an organic compound.
Ethyl carbamate – It is also known as urethane, is an organic compound with the chemical formula CH3CH2OC(O)NH2. It is an ester of carbamic acid and is a white solid. While its name includes ‘urethane’, it is not a component of polyurethanes.
Ethyl cyano-acrylate – is the primary liquid monomer in instant adhesives like ‘super glue’. It is a one-part, room-temperature curing adhesive that polymerizes instantly upon contact with moisture, forming a rigid, high-strength thermo-plastic bond across a variety of materials.
Ethyl-lead – It is also known as tetra-ethyl lead (TEL) with the chemical formula Pb(C2H5)4, is a toxic organo-metallic compound. It has been famously used as a gasoline additive to boost the octane rating, prevent engine ‘knocking’, and cushion exhaust valves.
Ethylene carbonate – It is a highly polar, cyclic organic solvent (C3H4O3) formed as the ester of ethylene glycol and carbonic acid. it acts as a premier ‘green’ solvent with a high dielectric constant, widely utilized in the formulation of electrolytes for lithium-ion batteries.
Ethylene chloro-trifluoro-ethylene – It is a high-performance, semi-crystalline, and melt-processible copolymer of ethylene and chloro-trifluoro-ethylene. Known for its exceptional chemical resistance, high mechanical strength, it is widely used in harsh environments as coatings and linings for tanks and pipes, with a functional temperature range of roughly -76 deg C to +150 deg C.
Ethylene-chloro-trifluoro-ethylene copolymer – It is a semi-crystalline thermoplastic copolymer composed of alternating units of ethylene and chloro-trifluoro-ethylene. It is known for its good chemical resistance, barrier properties, and high-frequency electrical characteristics. It is normally used in applications such as wire and cable coatings, and chemically resistant linings.
Ethylene-diamine-tetra-acetic acid – It is also called EDTA acid’ It is an amino-poly-carboxylic acid with the formula [CH2N(CH2CO2H)2]2. This white, slightly water-soluble solid is widely used to bind to iron and calcium ions, forming water-soluble complexes even at neutral pH. It is hence used to dissolve iron-containing and calcium-containing scale as well as to deliver iron ions under conditions where its oxides are insoluble.
Ethylene-ethyl acrylate – It is a polar ethylene co-polymer which shows adhesive characteristics because of its low crystallinity and high polarity, making it suitable for applications needing bonding capabilities, particularly in multi-layer packaging structures.
Ethylene glycol – It is an organic compound with the formula (CH2OH)2. It is mainly used for two purposes namely (i) as a raw material in the manufacture of polyester fibres and (ii) for antifreeze formulations. It is an odourless, colourless, flammable, viscous liquid. It has a sweet taste but is toxic in high concentrations.
Ethylene glycol derivative – It is a chemical compound synthesized from ethylene glycol (C2H6O2), which is a fundamental organic compound (ethane-1,2-diol). These derivatives are highly valued for their solvency, volatility, and ability to drastically alter freezing and boiling points. Derivatives of ethylene glycol fall into several primary structural categories, categorized by how they are processed and utilized:
Ethylene oxide – It is a colourless, flammable gas with a sweet odour. It is mainly used as a raw material for producing other chemicals, particularly antifreeze (ethylene glycol). Additionally, EtO is used as a sterilizing agent, especially for those devices which are heat-sensitive.
Ethylene plant – It is a large-scale industrial facility which produces ethylene (C2H4). It serves as a foundational building block for manufacturing plastics like poly-ethylene, as well as solvents, antifreeze, and synthetic fibres.
Ethylene propylene diene monomer – It is a versatile, high-performance synthetic rubber (elastomer) known for exceptional resistance to heat, ozone, UV (ultra-violet) exposure, and weathering. It is a terpolymer of ethylene, propylene, and a diene comonomer, normally used in automotive seals, roofing membranes, and gaskets.
Ethylene propylene diene monomer rubber – It is a synthetic thermoset rubber copolymer composed of ethylene and propylene, typically containing 45 % to 85 % ethylene, and characterized by its outstanding resistance to heat, ozone, and weather. It is normally cured with sulphur using diene components to improve cross-linking and improve performance properties.
Ethylene-propylene-diene rubber – It is known as EPDM (ethylene propylene diene monomer) rubber. The temperature resistance of this rubber is similar to butyl rubber but with a considerable higher resistance to wear and tear. It has also got a better ozone resistance.
Ethylene propylene rubber – It is a type of synthetic elastomer produced from ethylene and propylene monomers, known for its excellent resistance to heat, oxidation, ozone, and weathering. It is a versatile, flexible, and non-toxic material widely used in electrical cable insulation, automotive hoses, and seal applications, frequently offering a cost-effective alternative to natural rubber in harsh environments.
Ethylene tetra-fluoro-ethylene – It is a high-performance, fluorine-based thermoplastic copolymer designed for high corrosion resistance, strength, and durability over a wide temperature range. As a transparent, lightweight, and self-cleaning material, it is widely used in architecture for facades and roofs, as well as in electrical insulation.
Ethylene tetra-fluoro-ethylene copolymer – It is an advanced, melt-processable fluoro-polymer consisting of alternating ethylene and tetra-fluoro-ethylene units. Engineered to bridge the gap between standard plastics and fully fluorinated polymers like PTFE (poly-tetra-fluoro-ethylene), it combines high tensile strength, exceptional chemical inertness, and superb environmental and UV (ultra-violet) resistance.
Ethylene terephthalate – It is frequently referring to the polymerized form, poly-ethylene terephthalate (PET). It is a high-performance thermoplastic polyester. It is synthesized through the poly-condensation of ethylene glycol and terephthalic acid. It is highly valued for its exceptional tensile strength, dimensional stability, and resistance to chemicals and moisture. This polymer is a cornerstone for multiple industrial sectors because of its highly tunable physical and structural properties.
Ethylene vinyl alcohol – It is a flexible, thermo-plastic co-polymer of ethylene and vinyl alcohol. Engineered for its exceptional impermeability to gases (like oxygen and carbon di-oxide) and organic solvents, it is mainly used as a high-barrier layer in multi-layer packaging, and automotive fuel systems.
Ethyl group – It is an alkyl substituent with the formula −CH2CH3, derived from ethane (C2H6).
Ethyl mercaptan – It is also known as ethanethiol. It is a colourless liquid with a very pungent, skunk-like odour. It is an organo-sulphur compound with the formula C2H6S or CH3CH2SH, and its chemical structure resembles that of ethanol, but with a sulphur atom replacing an oxygen atom. The disagreeable odour has been described as penetrating, persistent, and garlic- or leek-like, similar to decaying cabbage. It is used as an intermediate and starting material in the manufacture of plastics, insecticides, and antioxidants, and as an odourant to serve as a warning property for natural gas.
Ethyl silicate – It is light brown liquid consisting predominantly of tetra-ethyl silicate with some poly-silicates which can be hydrolyzed with water to form alcohol and silicic acid. It is a strong bonding agent for sand and refractories used in preparing moulds in the investment casting process.
Ettringite – It is a mineral which forms part of the hydrated cement gel, and its delayed formation after concrete has set can lead to expansive stresses and cracking.
Ettringite formation – It is the chemical precipitation of a hydrous calcium aluminum sulphate mineral Ca6Al2(SO4)3(OH)12.26H2O within cement paste. While beneficial during the initial setting of concrete, delayed ettringite formation (DEF) in hardened concrete causes expansive internal stress, leading to cracking and structural degradation.
Euclidean distance – It is a measurement of distances between two vectors in Euclidean space, frequently used to assess the proximity of similar blocks in image processing to identify duplication or tampering.
Euclidean distance transform – It is an operator which converts a binary image into a distance map. For every pixel in the space, it calculates the straight-line (Euclidean) distance to the nearest boundary or obstacle pixel, yielding highly accurate proximity maps.
Euclidean geometry – It is the study of plane and solid figures based on the axioms and theorems. It describes the ‘flat’ geometry of everyday life, where parallel lines never meet, angles in a triangle sum to 180-degree, and the shortest distance between two points is a straight line.
Euclidean norm – It represents the physical magnitude or length of a vector in multi-dimensional space. It is the n-dimensional generalization of the Pythagorean theorem, used to calculate forces, signal strengths, and spatial distances.
Euclidean space – It is the fundamental, flat 3D framework used to model the atomic structure of crystals, micro-structure, and the physical space occupied by materials. It is defined as a space where Euclidean geometry applies, meaning distances and angles are measured using the standard formula derived from Pythagoras’ theorem, and parallel lines remain parallel.
Euler angles – These are a set of three independent rotational parameters used to describe the orientation or attitude of a rigid body in 3D space relative to a fixed reference frame. They are the foundation of motion analysis in aerospace, robotics, and automotive engineering. The system works by breaking a complex 3D rotation down into three sequential, elemental rotations around specific axes. These are three angular parameters which specify the orientation of a body with respect to reference axes.
Euler axis – It is the single, stationary, three-dimensional axis about which a rigid body rotates to get from its initial orientation to its final orientation. It is the physical realization of Euler’s rotation theorem, which dictates that any 3D spatial rotation can be fully defined by this single axis and an accompanying angle of rotation.
Euler backward method – It is also called backward Euler method or implicit Euler method. It is a first-order numerical technique for solving ordinary differential equations (ODEs), defined by the iterative formula ‘y(n+1) = y(n) + hf[t(n+1), y(n+1)]. It is an implicit method, meaning the unknown value ‘y(n+1)’ appears on both sides, needing equation solvers to determine the next step.
Euler beam – It is also called an Euler-Bernoulli beam. It is a simplified structural model used in engineering to calculate the load-carrying capacity and deflection of beams subjected to bending. It assumes the beam is slender and that its cross-sections remain perfectly plane and perpendicular to the axis during deformation.
Euler-Bernoulli beam theory – It is also called classical beam theory. It is a simplified mathematical method used to calculate how beams bend and deflect under loads. It assumes that plane sections remain plane and perpendicular to the neutral axis after deformation, focusing on bending effects while ignoring shear deformation and rotary inertia. It is defined as a fundamental theory which analyzes beam deflections and natural frequencies while assuming that the cross-section of a beam remains plane and normal to the deformed axis after deformation, disregarding shear deformation and rotary inertia effects. This theory is applicable mainly to slender, isotropic, homogeneous beams with simple cross-sections.
Euler buckling – It is a structural failure mode in which a long, slender column subjected to an axial compressive load suddenly bows or deflects sideways instead of just compressing. This buckling occurs at a specific threshold called the critical load (or crippling load), which can happen long before the material reaches its yield or crushing strength.
Euler equations – These equations can be defined as the simplified governing equations which describe the pure convection of flow quantities in an inviscid fluid, got by omitting viscous effects from the Navier-Stokes equations. These are used to represent phenomena such as shocks, expansion waves, and vortices.
Eulerian approach – It is a method for solving finite element problems where nodes corresponding to the working volume are fixed in space, allowing for the analysis of material flow through a defined control volume. This approach eliminates issues related to mesh distortion but can complicate boundary condition definitions and material constitutive equations.
Eulerian-based finite element method – It is a numerical simulation approach where the mesh (grid) remains fixed in space while material flows through it. Unlike the traditional Lagrangian approach, where the mesh moves and deforms with the material, the Eulerian mesh is stationary, allowing for the analysis of large deformations, fluid flows, and moving boundaries without encountering mesh distortion issues.
Eulerian coordinate – It is also called frame of reference. It tracks the physical properties of a flowing medium, such as velocity, pressure, or temperature, at fixed spatial locations over time, rather than following individual particles.
Eulerian-Eulerian approach – It is a modeling technique in ’computational fluid dynamics’ (CFD) where two or more phases, such as gas, liquid, or solid, are treated as interpenetrating continua. Instead of tracking individual particles, it solves conservation equations for mass, momentum, and energy for each phase over a fixed spatial grid, making it highly efficient for dense, high-volume fraction multiphase flows.
Eulerian frame – It is a fixed reference frame where an observer monitors properties, such as velocity, pressure, and temperature, at stationary points in space over time, rather than tracking individual moving particles. This approach is highly analogous to sitting on the bank of a river and watching the water flow past a specific point, rather than getting into a boat and floating downstream (which is a Lagrangian frame).
Eulerian mesh – It is a stationary, fixed grid in space used in numerical simulations (like finite element analysis or computational fluid dynamics) where the mesh remains completely rigid while the material or fluid flows through it. Instead of following individual particles, this framework calculates physical properties at fixed points, making it ideal for severe deformations, multi-phase flows, and high-speed impacts.
Eulerian method – It is a modelling technique where the mesh remains fixed in space while the material flows through it, normally used for simulating fluid behaviour in computational analysis.
Eulerian model – It is a mathematical framework which describes fluid flow and moving phases (like particles or bubbles) within a fixed coordinate system. Rather than tracking individual particles, it treats each phase as an inter-penetrating continuum, calculating properties like average velocity, volume fraction, and pressure on a stationary mesh. The Eulerian model handles complex systems by solving individual sets of conservation equations for each phase present.
Eulerian multi-phase approach = It (or Eulerian-Eulerian model) is a computational fluid dynamics (CFD) method that treats all phases in a fluid mixture (gas, liquid, or solid) as inter-penetrating continua. It solves individual sets of conservation equations (mass, momentum, and energy) for each phase.
Eulerian representation – It is a framework used to analyze fluid flow or solid mechanics by observing physical properties at fixed points in space over time, rather than tracking individual moving particles.
Eulerian velocity field – It defines fluid motion at fixed points in space over time, rather than tracking individual fluid particles. It describes velocity (v) as a mathematical function of a fixed spatial coordinate {x} = (x, y, z) and time (t).
Euler-Lagrange equation – It is a fundamental differential equation in the calculus of variations. It is used to find the path, motion, or state which minimizes or maximizes a system’s total action or energy. It forms the mathematical foundation of Lagrangian mechanics.
Euler load – It is the theoretical maximum compressive axial force a long, slender column can support before it suddenly bends or buckles. It marks the point of structural instability rather than material failure.
Euler model – It very frequently refers to the Euler-Euler multiphase model. It is a computational framework used to model two or more distinct phases (like solids, liquids, or gases) simultaneously. Instead of tracking individual particles, it treats each phase as an interpenetrating continuum, using averaged transport equations.
Euler number – it is a dimensionless parameter in fluid mechanics used to analyze pressure drops in flowing fluids. It represents the ratio of pressure forces to inertial forces, helping engineers quantify energy losses across pipes, valves, and flow restrictions.
Euler pump and turbine equations – These are the most fundamental equations in the field of turbo-machinery. These equations govern the power, efficiencies and other factors that contribute to the design of turbomachines. With the help of these equations the head developed by a pump and the head utilized by a turbine can be easily determined. These equations can be derived from the moment of momentum equation when applied for a pump or a turbine.
Euler’s column buckling theory – It is a fundamental structural concept used to determine the maximum axial load a long, slender column can support before it becomes unstable and bows outward (buckles). Rather than failing by crushing or yielding, columns fail through elastic instability, which occurs when the compressive load exceeds a specific threshold.
Euler’s formula – It is a fundamental mathematical equation in complex analysis which connects exponential functions with trigonometry. It is the theorem which states that ’eix = cosx + isinx’, ‘x’ is a real number., ‘e’ is the base of the natural logarithm, and ‘i’ is the imaginary unit (i.e., square root of −1). Euler’s formula establishes the fundamental relationship between trigonometric functions and exponential functions. Geometrically, it can be thought of as a way of bridging two representations of the same unit complex number in the complex plane. It is widely used to simplify calculations involving oscillations and waves.
Euler’s rotation theorem – It states that, in three-dimensional space, any displacement of a rigid body with a fixed point is equivalent to a single rotation about some fixed axis (the Euler axis) running through that point. This simplifies complex spatial movements into a single rotation angle around a specific vector.
Euler scheme – It is a fundamental numerical procedure to approximate solutions to ordinary differential equations (ODEs) or to simulate dynamic systems step-by-step when an exact, analytical solution cannot be easily found.
Euler solution – It typically refers to the Euler method. It is a numerical technique for solving differential equations, or it can describe the Euler equations used in fluid dynamics to model inviscid flow.
Euler space – It is a three-dimensional mathematical parameter space used to define the orientation of a rigid body or coordinate frame in 3D space, typically defined by three successive rotations (phi-1, phi, phi-2) about specified axes.
Euler theory – It is defined as a mathematical framework which describes the critical buckling stress of columns, which is influenced by the column’s slenderness ratio and its material properties. It predicts which for long and slender columns, the critical stress is low, while for short columns with larger cross-sectional areas, the critical stress is high.
Eurocodes – These are a suite of ten harmonized European standards (EN 1990 to EN 1999) developed for the structural and geotechnical design of buildings and civil engineering works across the European Union. They ensure the mechanical strength, stability, and fire safety of structures. Developed by the European Committee for Standardization, these codes replaced varying national building regulations to create a unified framework for the construction industry.
European Norms (EN) – It is also known as European Standards. These are technical standards developed and maintained by the European Standards Organizations (ESOs) CEN (European Committee for Standardization), CENELEC (European Committee for Electrotechnical Standardization), and ETSI (European Telecommunications Standards Institute) providing a common language and technical specifications for products, processes, and services within the European market.
Europium (Eu) – It is a chemical element having atomic number 63. It is a silvery-white metal of the lanthanide series which reacts readily with air to form a dark oxide coating. Europium is the most chemically reactive, least dense, and softest of the lanthanides. It is soft enough to be cut with a knife. Europium normally assumes the oxidation state +3, like other members of the lanthanide series, but compounds having oxidation state +2 are also common. All europium compounds with oxidation state +2 are slightly reducing because of their tendency to get oxidized into the more stable +3 state. It is relatively non-toxic compared to other heavy metals. Most applications of europium exploit the phosphorescence of europium compounds. Europium is one of the rarest of the rare-earth elements on the earth.
Eustis process – It is a hydrometallurgical, cyclic method for extracting high-purity iron directly from iron sulphide ores, such as pyrrhotite [Fe(1-x)S] or pyrites (FeS2), without traditional smelting. It uses electro-winning in a concentrated ferric / ferrous chloride (FeCl3 / FeCl2) solution to dissolve the ore and deposit metallic iron, concurrently producing elemental sulphur as a by-product. The Eustis process is the leaching of finely divided pyrrhotitic iron sulphide ore using an aqueous solution of iron chloride, followed by the electrolysis of the resulting iron-rich liquor to recover electrolytic iron.
Eutectic – It is an isothermal reversible reaction in which a liquid solution is converted into two or more intimately mixed solids on cooling, the number of solids formed being the same as the number of components in the system. It is also an alloy having the composition indicated by the eutectic point on a phase diagram. Eutectic is also an alloy structure of intermixed solid constituents formed by a eutectic reaction frequently in the form of regular arrays of lamellas or rods.
Eutectic alloy – It is the alloy composition which freezes at constant temperature similar to a pure metal. It is the lowest melting (or freezing) combination of two or more metals. The alloy structure (homogeneous) of two or more solid phases formed from the liquid eutectically.
Eutectic arrest – In a cooling or heating curve, it is an approximately isothermal segment corresponding to the time interval during which the heat of transformation from the liquid phase to two or more solid phases are evolving.
Eutectic bonding – It is a wafer and die-level joining technique which uses an intermediate metal layer to form a joint between two surfaces at a temperature considerably lower than the melting points of the individual materials. This process is heavily utilized in the semi-conductor, MEMS (micro-electro-mechanical systems), and – industries.
Eutectic carbide – It is the carbide formed during freezing as one of the mutually insoluble phases participating in the eutectic reaction of ferrous alloys.
Eutectic-cell etching – It consists of the development of eutectic cells (grains).
Eutectic melting – It is the melting of localized microscopic areas whose composition corresponds to that of the eutectic in the system.
Eutectic phase – It is a specific, intimate solid mixture of two or more components which solidifies at a single, minimum, and constant temperature, lower than the melting points of its individual constituents. It acts like a pure substance by freezing directly from a liquid to a solid at a specific ‘eutectic point’.
Eutectic point – It is the composition of a liquid phase in univariant equilibrium with two or more solid phases. It is also the lowest melting alloy of a composition series.
Eutectic reaction – It is a type of ‘invariant reaction’ where a single liquid phase transforms directly into two distinct solid phases upon cooling, at a specific constant temperature and composition. Known as ‘easy melting’, this process yields a fine, intermingled microstructure (frequently layered).
Eutectic salt-water solution – It is a specific, precise mixture of salt and water which possesses the lowest possible freezing point for that combination of substances. Unlike typical solutions, it freezes and melts completely at one constant temperature, transitioning directly between liquid and solid states without becoming mushy.
Eutectic silicon – It refers to the silicon which precipitates out of hypo-eutectic or near-eutectic metal alloys, very frequently in aluminum-silicon (Al-Si) casting alloys. It forms a microscopic, eutectic phase characterized by specific crystalline morphologies which heavily dictate the mechanical properties of the material.
Eutectic solidification – It is a metallurgical process where a liquid alloy transforms directly into two distinct solid phases simultaneously at a single, constant temperature, which is the lowest possible melting point for that system. It occurs in a specific composition (eutectic mixture) which acts like a pure metal, melting and freezing sharply without a temperature range.
Eutectic structure – It is an intimate, finely mixed solid micro-structure formed when a liquid alloy of a specific composition (the eutectic composition) solidifies at a constant, minimum temperature (the eutectic temperature). It represents a simultaneous crystallization of two or more solid phases directly from the liquid, frequently producing layered (lamellar) or rod-like patterns, rather than forming a single solid solution.
Eutectic system – It is a homogeneous mixture of two or more components (normally metals or compounds) which solidifies or melts at a single, consistent temperature lower than the melting point of any individual constituent. It forms at a specific ratio, known as the eutectic composition.
Eutectic system with solid solution – It is a specific mixture of substances (typically alloys) which are fully soluble in the liquid state but have limited, partial solubility in the solid state. It melts or solidifies at a single, minimum temperature, the eutectic point, which is lower than the melting points of its individual constituents.
Eutectic temperature – It is the lowest possible melting point over all of the mixing ratios of the constituents of an alloy. On a phase diagram, the eutectic temperature is seen as the eutectic point.
Eutectic-type solidification – It is a phase transformation process where a homogeneous liquid solution, upon cooling, simultaneously transforms into two or more distinct solid phases at a specific, constant temperature. This temperature is the lowest melting point among all possible compositions of the components involved
Eutectoid – It is an isothermal reversible reaction in which a solid solution is converted into two or more intimately mixed solids on cooling, the number of solids formed being the same as the number of components in the system. It is also an alloy having the composition indicated by the eutectoid point on a phase diagram. Eutectoid is an alloy structure of intermixed solid constituents formed by a eutectoid reaction.
Eutectoid composition – It is the exact proportion of alloy elements in which a single solid phase transforms directly into two distinct solid phases upon cooling. This transformation happens simultaneously at a specific, fixed temperature known as the eutectoid temperature.
Eutectoid ferrite – It is the body-centred cubic (bcc) iron phase formed during the slow cooling of austenite in the iron-carbon (Fe-C) system. It forms exclusively within pearlite, a lamellar, alternating-plate mixture of ferrite and cementite (Fe3C).
Eutectoid point – It is the composition of a solid phase which undergoes univariant transformation into two or more other solid phases upon cooling.
Eutectoid reaction – It is a solid-state transformation where a single solid phase solid-1 decomposes upon cooling into two distinct solid phases solid-2 + solid-3 at a specific temperature and composition. It is an invariant reaction frequently forming a lamellar structure (like pearlite in steel) and occurs completely in the solid state.
Eutectoid steels –These are the steels representing the eutectoid composition of the iron-carbon system with around 0.80 % to 0.83 % C and the eutectoid temperature of around 723 deg C. Such steels in the annealed condition consist exclusively of pearlite. The presence of certain elements, such as nickel or chromium lowers the eutectoid carbon content.
Eutectoid structure – It is a finely mixed micro-structure formed when a single solid phase decomposes into two distinct solid phases upon cooling, typically creating a lamellar (plate-like) morphology. It occurs at a specific, invariant temperature and composition where the high-temperature phase transforms into two new solid phases simultaneously.
Eutectoid temperature – It is the specific temperature at which a single, high-temperature solid phase transforms simultaneously into two distinct solid phases upon cooling. It acts as a critical anchor point in metallurgical phase diagrams.
Eutectoid tool steel – It is a type of carbon steel containing around 0.76 % to 0.83 % carbon, which transforms entirely from austenite to a 100 % pearlite micro-structure upon cooling through the eutectoid temperature (around 727 deg C). It is characterized by high strength, wear resistance, and hardness, containing alternating layers of ferrite and cementite.
Eutectoid transformation – It is a solid-state reaction where a single solid phase decomposes into two distinct, alternating solid phases upon cooling, occurring at a specific temperature and composition. It is an invariant reaction (Gibbs free energy change is zero) where the new solid phases frequently form a lamellar structure.
Eutrophication – It is a process in which nutrients accumulate in a body of water, resulting in an increased growth of microorganisms which can deplete the oxygen in water. The discharge of nitrogenous and phosphorous compounds into receiving water-bodies can alter their fertility. Enhanced fertility can lead to excessive plant growth. The latter can include algal growth. The subsequent impact of such growth on a water-body can include increased turbidity, oxygen depletion, and toxicity issues. Algal growth in unpolluted water-bodies is normally limited since the water is nutrient limiting. While nutrients include macro-nutrients like nitrogen, phosphorous, and carbon, and micro-nutrients like cobalt, manganese, calcium, potassium, magnesium, copper, and iron which are needed only in very small quantities, the focus in concerns over eutrophication is on phosphorous and nitrogen since the quantities of the other nutrients in the natural environment are frequently inherently adequate.
Eutrophication potential – It is an environmental impact indicator measuring a substance’s capacity to cause over-fertilization in water and soil. It quantifies the emissions generated during metal extraction and processing which contain excess nitrogen and phosphorus, which trigger harmful algal blooms and severe oxygen depletion in aquatic ecosystems.
Evacuated tube collector – It is a high-efficiency solar thermal device which utilizes parallel glass tubes enclosing a vacuum-sealed, insulated space. This design traps solar radiation to heat a working fluid while drastically minimizing convective and conductive heat loss, enabling exceptional thermal performance even in freezing or cloudy conditions.
Evacuated tube solar collector – It is a highly efficient solar thermal device which absorbs solar radiation to generate heat. It consists of parallel rows of glass tubes containing a vacuum to provide near-perfect thermal insulation, ensuring minimal heat loss even in freezing, windy, or overcast conditions.
Evaluation – It is a systematic determination and assessment of a subject’s merit, worth and significance, using criteria governed by a set of standards. It can assist an organization, programme, design, project or any other intervention or initiative to assess any aim, realizable concept / proposal, or any alternative, to help in decision-making, or to generate the degree of achievement or value in regard to the aim and objectives and results of any such action that has been completed.
Evaluation authority – It is a designated entity, committee, or body responsible for conducting rigorous, systematic assessments of programmes, projects, or policies to determine their merit, value, and achievements. They ensure objective decision-making, frequently focusing on evidence-based policy making, performance monitoring, and compliance with standards.
Evaluation criteria – These are the specific, predefined standards, benchmarks, or metrics used to assess, compare, and judge the quality, value, or suitability of proposals, products, projects, or performance. They ensure objective, consistent decision-making, transforming subjective opinions into measurable, transparent results.
Evaluation matrix – It is also called decision matrix. It is a structured, quantitative tool used to compare and rank multiple design alternatives or project solutions. It objectively scores options against pre-defined criteria (like cost, weight, and durability), eliminating personal bias to find the most viable solution.
Evaluation operator – It is a formal mapping which takes a state, variable, or system space and judges its effectiveness, output, or adherence to requirements. Depending on the engineering context, it measures performance, computes mathematical operations, or represents a specific function within the system life-cycle.
Evaluation process – It goes through four distinct phases namely planning, implementation, completion, and reporting. While these mirror common programme development steps, it is important to remember that a person’s evaluation efforts cannot always be linear.
Evaluation of metals – It involves analyzing the composition, properties, and structural integrity of metallic materials to determine their suitability for specific applications, identify failures, or verify material standards (International Organization for Standardization, ISO). It combines physical testing (hardness, ductility) with chemical analysis to ensure quality and reliability.
Evaluation of property data – It is the process of establishing the accuracy and integrity of property data by appraisal of the data presented, assessment of the experimental technique and its associated errors, and checking for consistency of values and comparison with other experimental or theoretical values.
Evaluation report – It is a document which distills and articulates the outcomes and findings of an evaluation process, incorporating both qualitative and quantitative aspects. It is tailored to different audiences and serves as a basis for informed decision-making in programming choices and practices.
Evaluator – It is a systematic testing framework, a physical hardware prototype, or a specialized technical professional that assesses whether a product, system, or AI (artificial intelligence) model meets predefined safety, efficiency, and performance standards.
Evanescent – It refers to light which does not propagate but instead decays in intensity over a sub-wave-length distance, playing an important role in techniques such as fluorescence microscopy for surface-selective imaging and measurement of fluorophore orientation.
Evanescent field – It is an oscillating electric or magnetic field which decays exponentially with distance without carrying energy away. It stays tightly confined near the source or boundary and allows for non-radiative energy transfer across very small gaps.
Evanescent wave – It is an oscillating electro-magnetic field which does not propagate as a wave but instead decays exponentially with distance from an interface. Formed during total internal reflection at boundaries between different refractive indices, these ‘near-field’ waves exist only within a short distance, roughly one wave-length, from the surface.
Evaporated atom – It is a particle of source material which has gained enough thermal or electrical energy to escape into a vapour state, typically within a vacuum. These atoms travel freely and condense onto cooler surfaces to form thin films or coatings.
Evaporated carbon – It is a material produced by vapourizing solid graphite in a high-vacuum environment using resistive heating or an electron beam. The resulting carbon vapour condenses on cooler surfaces to form ultra-thin, highly pure, amorphous films valued for their mechanical strength, high thermal conductivity, and low atomic number.
Evaporated coating – It is a physical vapour deposition (PVD) process where a source material is heated inside a high-vacuum chamber until it vapourizes. The vapourized particles travel unimpeded and condense onto a target substrate, forming an ultra-thin, precise, and uniform film.
Evaporated water – It is the mass of liquid water which has absorbed enough thermal energy to undergo a phase change into a gas (water vapour). It describes the quantity of water lost or utilized through this transition, a critical factor for cooling systems, waste-water processing, and hydrology.
Evaporating meniscus – It is the ultra-thin region of fluid where a liquid-vapour interface meets a solid, heated surface. It acts as a main pathway for highly efficient heat transfer, driving evaporation by relying on micro-scale liquid flow and capillary forces.
Evaporating pressure – It is also called suction pressure or low-side pressure. It is the specific pressure maintained within an evaporator. It dictates the temperature at which a fluid boils and absorbs heat. Lowering this pressure lowers the fluid’s boiling point, which is the foundational principle of vapour-compression refrigeration and HVAC (heating, ventilation, and air conditioning) systems.
Evaporating temperature – It is the specific temperature at which a fluid transitions from a liquid state to a vapour state under constant pressure. It is the temperature at which a refrigerant changes from liquid to vapour within the evaporator, affecting heat transfer efficiency and exergy loss in vapour compression refrigeration systems. Higher evaporating temperatures lead to increased refrigerating effect and reduced exergy losses.
Evaporation – It is the vapourization of a material by heating, normally in a vacuum. In electron microscopy, this process is used for shadowing or to produce thin support films by condensation of the vapours of metals or salts.
Evaporation capacity – It refers to the quantity of volatile solvent which can be vapourized, typically measured in terms of tons of water per hour, particularly in large-scale operations.
Evaporation-condensation process – It is a thermodynamic phase-change cycle. It converts a liquid into a vapour by absorbing thermal energy (evaporation), transports the vapour, and converts it back to a liquid to release latent heat (condensation). This closed-loop mechanism transfers immense heat with minimal temperature differences. This process forms the backbone of highly efficient thermal management and fluid transport systems.
Evaporation momentum force – It is also known as the vapour recoil force. It is the steady reaction force exerted on a liquid-vapour interface when liquid evaporates. Since vapour has a much lower density and leaves the surface at a higher velocity than the approaching liquid, this net momentum-change pushes back on the liquid.
Evaporation ponds – These are artificial ponds with very large surface areas which are designed to efficiently evaporate water by sunlight and expose water to the ambient temperatures. Evaporation ponds are inexpensive to design making them ideal for multiple purposes such as waste-water treatment processes, storage, and extraction of minerals. Evaporation ponds differ in purpose and can result in a wide range of environmental and health effects. Salt evaporation ponds produce salt from seawater. Evaporation ponds are used to extract lithium from underground brine solution. The extracted lithium is then used to make ion batteries. Mines use them to separate ore from water. The ore can be sold for use in different industries. Potash evaporation ponds are used to extract potassium from the mineral rich solution.
Evaporation point – It is frequently referred to within the context of vacuum metallurgy or thin-film deposition. It is the temperature at which a metal’s surface atoms or molecules gain sufficient kinetic energy to escape its liquid or solid phase and enter the gaseous (vapour) phase. This process is highly pressure-dependent and is frequently utilized in vacuum environments, such as during thermal evaporation thin film deposition.
Evaporation rate – It is the mass, volume, or molar quantity of a liquid which transforms into vapour per unit of time and exposed surface area. It is a critical parameter used to size ventilation systems, design industrial dryers, and assess the fire or health hazards of volatile chemicals.
Evaporation retarder – It is also called evaporation retardant. It is a specialized chemical solution applied to freshly poured concrete. It forms a temporary, invisible, one-molecule-thick film on the surface which traps bleed water, considerably slowing moisture loss in hot, dry, or windy conditions.
Evaporation temperature – It is also called boiling point. It is the specific temperature at which a liquid changes into a gas (vapour) under a given pressure. It is dictated by the exact relationship between the vapour pressure of the liquid and the surrounding ambient pressure.
Evaporative condenser – It is a heat exchanger which condenses high-pressure refrigerant vapour into a liquid by spraying water over exterior condenser coils while continuously blowing ambient air across them. It essentially functions as a hybrid between a water-cooled condenser and a cooling tower, leveraging the latent heat of vapourization to dramatically improve energy efficiency.
Evaporative deposition – It is the techniques of condensing a thin film of material on a substrate. The entire process takes place in a high vacuum. The source material may be radioactively heated by bombardment with electrons (electron-beam radiation) or can be heated by thermal-conduction techniques.
Evaporative loss – It refers to the reduction in volume, mass, or efficiency of a fluid or material because of its conversion from a liquid into a gas or vapour. This phenomenon is studied across different disciplines, and the specific definition changes depending on the system.
Evaporative pattern casting – It is also called lost foam casting. It is a type of investment casting which uses a polystyrene foam pattern which evaporates (vapourizes) upon contact with molten metal. This sand-casting process eliminates the need to remove the pattern, allowing for complex geometries without parting lines or cores.
Evaporative pattern (mould) casting process – It is a type of casting process which uses a pattern made from a material which evaporates when the liquid metal is poured into the mould cavity. This means that there is no need to remove the pattern material from the mould before casting. The most common evaporative-pattern material used is polystyrene foam. The two main processes are lost foam casting and full mould casting.
Evaporative resistance – It is a measure of a material’s ability to impede the transfer of water vapour from a surface to the surrounding environment. It is a critical metric in textile engineering and ergonomics for evaluating thermal comfort, moisture management, and heat stress.
Evaporative stave cooling, natural (NEVC) – It is a technique where boiler quality water is introduced into the bottom row of staves and flows by natural mean up the vertical cooling circuits. As the process heat conducts through the stave and cooling pipe into the water, the water in turn heats up. As the water warms, it expands. Since cooler water is being introduced below, the warm water tends to move upwards. At some point in the vertical cooling circuit, the water is at the boiling point. As the water changes its phase to steam, due to the latent heat of vapourization, additional heat is absorbed (driving the phase change). After boiling begins, two-phase flow (water and steam mixture) ascends the cooling pipes to the top of the furnace. Normally located on the furnace top platform are steam separator drums used to extract and vent the steam to atmosphere. Make-up water is introduced to the drum (to replace the discharged steam). The water is piped back by gravity to the furnace bottom and is fed once more to the staves. This cooling technique is very efficient and has low operating costs. There is no pumping equipment.
Evaporative stave cooling, forced – It is the improvements in natural evaporative stave cooling. In this system the flow of the cooling water gets a boost with recirculating pumps (forced evaporative cooling, FEVC) in order to ensure uniform cooling water flow and to cool the recirculating water (forced cold water cooling, FCWC).
Evaporator – It is an equipment wherein evaporation occurs, i.e. liquid is evaporated from a thin (low-density) feed material in order to produce a denser or thicker product (concentrate). The feed can be a solution, slurry or suspension of solid materials in a liquid.
Evaporator capacity – It is the total mass of solvent (normally water) vapourized by an evaporator per unit of time. It is typically expressed in kilograms per hour or tons per hour and dictates the processing throughput of an industrial unit.
Evaporator circuit – It is a distinct fluid pathway within an evaporator heat exchanger where a liquid absorbs thermal energy and boils into a vapour. It dictates how refrigerant mass flow or process fluid is distributed to optimize heat transfer, maintain uniform pressure drops, and prevent liquid from entering the compressor. The engineering principles, design criteria, and primary functions of evaporator circuits focus on several key factors.
Evaporator pressure – It is the internal operating pressure inside an evaporator. In refrigeration / HVAC (heating, ventilation, and air conditioning), it dictates the boiling point of the refrigerant. In chemical / process engineering, it dictates the boiling point of the solution being concentrated. Adjusting this pressure directly controls the phase-change temperature.
Evaporator region – It is the specific zone within a thermal system where a working fluid absorbs heat and undergoes a phase change from liquid to vapour. It serves as a primary heat exchanger designed to transfer thermal energy into the fluid.
Evaporator section – It is a heat exchanger where a liquid absorbs thermal energy and undergoes a phase change into a vapour. Its primary function is either to remove heat from an environment (refrigeration) or to concentrate liquid solutions by boiling off solvents (chemical / process engineering).
Evaporator system – It is an engineered unit operation which uses heat transfer to convert a liquid into a vapour, normally to eliminate water, eliminate volatile solvents, or extract heat from a surrounding medium.
Evaporator temperature – It is the specific temperature at which a liquid refrigerant undergoes a phase change into a vapour while absorbing heat in an evaporator. This metric is directly controlled by the system’s pressure and determines the equipment’s cooling capacity and overall heat transfer efficiency.
Event – An event is an occurrence unintended by the operator, including operating error, equipment failure, or other mishap, and deliberate action on the part of others, the consequences or potential consequences of which are not negligible from the point of view of protection and safety.
Event-driven programming – It is a software engineering design paradigm where the flow of execution is determined by external occurrences or signals called events, such as user actions, system notifications, or sensor outputs. Unlike traditional procedural models that follow a strict, linear sequence of instructions, event-driven applications remain in an idle state or execute background tasks until an event occurs to trigger a specific response.
Even tension – It is the process whereby each end of roving is kept in the same degree of tension as the other ends making up that ball of roving.
Event handler – It is a callback function which automatically executes in response to a specific trigger or system action, such as a user clicking a button, a key-stroke, or a database update. It is the foundation of event-driven programming, allowing applications to act asynchronously rather than executing in a strict, linear sequence.
Event, networking – An event represents a point in time signifying the completion of some activities and the beginning of new ones. This is normally represented by a circle in a network which is also called a node or connector. The events are classified in to three categories namely (i) merge event which is when more than one activity comes and joins an event, (ii) burst event which is when more than one activity leaves an event, and (iii) merge and burst event which is when an activity can be merge and burst event at the same time as with respect to some activities it can be a merge event and with respect to some other activities it can be a burst event.
Event tree analysis – It is a binary logic tree for tracing all the possible consequences of an event. Unlike the fault tree, the event tree starts with an initiating event and traces all possible consequences. It is also a graphical method of exploring how an initiating (hazardous) event can lead to an accident through a set of further events. The method allows the exploration of barriers to escalation of the hazard (mitigations) and the calculation of the relative likelihoods of different outcomes.
Event-triggered control – It is a strategy which updates control signals only when specific conditions are violated, rather than at fixed time intervals. By breaking the traditional time-driven loop, it minimizes unnecessary computations and data transmissions, optimizing network bandwidth and extending the battery life of embedded systems.
Evolution – It refers to the iterative, continuous process of refining, adapting, and improving a system, software, or product in response to changing requirements, user feedback, and technological advancements. Instead of a fixed, static end state, the system is designed to continuously adapt and scale.
Evolutionary design – It is an iterative approach where systems, products, or software are not fully planned out at the beginning. Instead, a minimal working version is created and incrementally adapted through continuous testing, user feedback, and changing requirements, allowing the design to organically mature over time.
Evolutionary engineering – It is a method which mimics natural selection to design or optimize complex systems. Rather than relying on a single, perfectly calculated blueprint from the start, it introduces small variations into a system and repeatedly tests and selects the best-performing versions over multiple generations.
Evolutionary function – It refers to a set of practices which allow mathematical, functional, or system requirements to adapt and improve over time based on iterative feedback, environmental changes, or continuous machine learning. It bridges multiple disciplines.
Evolutionary phase – It refers to an iterative, phased development model where a system or product is built, delivered, and continuously refined over successive versions based on stakeholder feedback. Rather than attempting a final big bang’ release, engineers build a basic working model and incrementally add features.
Evolution function – It is a mathematical formula, algorithm, or process used to optimize systems, track material degradation, or continuously update software by imitating natural selection. It guides a system from a baseline state toward a highly adapted, optimal end state over time.
Evolution law – It defines how a system, material, or software changes over time. Depending on the discipline, it acts as a predictive model for material degradation, software maintenance, or the physical design of flow systems. It refers to the specified patterns, such as linear or exponential, which define the progression of damage in materials, particularly how the damage factor increases from 0 to 1, leading to a gradual degradation of material stiffness until complete failure occurs.
Evolution operator – It is also called time-propagator. It is a mathematical operator which advances a system’s state or observable from an initial time to a future time. It maps the system’s configuration forward through time while preserving the underlying physical rules of the system.
Evolution period – It is also called evolutionary phase It is an iterative stage in system development where a product, software, or design is continuously refined and expanded through sequential cycles of prototyping, testing, and user feedback.
Evolution rule – It involves creating mathematical or logical frameworks which that describe how systems, materials, or software change over time. It is critical for predicting material degradation (e.g., fatigue or damage evolution laws), optimizing algorithms (e.g., evolutionary computing), and managing software architecture life-cycles.
Evolved packet core – It is the framework for converged voice and data on 4G LTE (fourth generation long term evolution) mobile networks. As an all-IP (internet protocol), packet-switched core network, it replaces older circuit-switched systems to deliver data, authenticate users, and manage seamless mobility across different access technologies.
Ewald sphere – It is a geometric construction, of radius equal to the reciprocal of the wave-length of the incident radiation, with its surface at the origin of the reciprocal lattice. Any crystal plane will reflect if the corresponding reciprocal lattice point lies on the surface of this sphere.
E-waste – It consists of the waste materials generated from using or discarding electronic devices, such as computers, televisions, and mobile phones. E-waste tends to be highly toxic to humans, plants, and animals, and has been known to contaminate water, air, and dirt. It causes concern since several of the components used in these products are toxic and are not bio-degradable.
Example – It is a specific instance, sample’ or case which represents a larger group, illustrates a general rule, or serves as a model to be imitated. It functions to clarify, justify, or demonstrate a concept, such as a ‘sample’ of a product or a ‘case’ used by trainer for the training of the employees.
Exact integration – It is the process of calculating an integral such that a polynomial of degree (2nQ – 1) can be accurately integrated using (nQ) quadrature points, typically performed using Gauss quadrature. However, achieving exact integration is frequently challenging in meshfree methods because of the non-polynomial nature of meshfree shape functions.
Exact model – It is a formal learning model where the learner’s objective is to precisely identify an unknown binary target function from a known concept class, using membership and equivalence queries to ascertain how the function classifies instances from its domain.
Exact potential game – It is a strategic-form game where any change in a single player’s utility (payoff) resulting from a unilateral action matches the exact change in a globally defined ‘potential function’. It aligns individual selfish incentives with a system-wide objective.
Exact theory – It is a mathematical model derived directly from fundamental physical principles without introducing simplifying approximations or assumptions. It provides rigorously derived, exact solutions for behaviours such as structural mechanics, thermodynamics, or fluid dynamics, though it frequently relies on complex non-linear equations. Since exact theories, such as geometrically exact beam theory or exact differential equations, can be highly complex to solve, engineers typically use them as a base-line to validate approximate numerical models (e.g., finite element analysis) or in highly specialized, safety-critical civil designs.
Excavation method – It refers to the specific techniques and systems used to safely remove soil, rock, or other earthen materials from a site. It is a fundamental process needed to prepare building foundations, create underground spaces, or install subterranean utilities. Selection of the techniques depends on geological conditions, project scale, and water management needs.
Excavation, rock – It is the removal of hard, compacted, or cemented materials which cannot be excavated with standard earth-moving or heavy ripping equipment (such as bull-dozers or standard back-hoes).
Excavation surface – It is the exposed area created during digging operations where earth, rock, or construction materials are actively removed. Defining this surface needs precise calculations of cut slopes, grade tolerances, and shoring limits to ensure structural stability and manage ground-water before installing foundations or utilities.
Excavator– It is a self-propelled crawler or wheel mounted machine, with an upper structure, capable of a minimum of 360-degree rotation. It excavates, elevates, swings, and discharges material, by the action of a bucket fitted to the boom and arm or telescopic boom, without moving the chassis or under-carriage, during any part of the working cycle, of the machine. Hydraulic excavator is a multi-purpose earthmoving machine, which can perform several duties, in the field, such as digging earth, mining, loading, quarrying, etc., apart from other activities like well-digging, and material handling. The excavator is the only earth-moving machine, capable of, working in three dimensions and in all the directions.
Exceedance – It refers to the probability that a natural extreme event exceeds a specified intensity over a given period, highlighting the relationship between return periods and the reliability of structures against potential destructive effects.
Excellent di-electric properties – These refer to a material’s capacity to act as an electrical insulator while being highly responsive to an external electric field. This combination allows materials to effectively store electrical energy (in capacitors) or guide electro-magnetic waves while minimizing energy loss as heat.
Excel spreadsheet – It is a dynamic, grid-based software document which organizes data into rows and columns. It serves as a powerful computational tool to manage technical variables, automate design calculations, analyze test data, and generate technical reports.
Excel table – It is a powerful feature which allows users to manage and analyze tabular data, enabling functionalities such as filtering, automatic formula extension, and dynamic updates when new data is added.
Exception handler – It is a dedicated block of code or routine that intercepts abnormal events (exceptions) during execution. It prevents system crashes, preserves state, and dictates how the software responds to errors, such as bad inputs, lost network connections, or memory faults. Exception handling is a structured software engineering mechanism which separates normal business logic from error-recovery operations. Without it, runtime anomalies cause abrupt programme termination.
Exception return mechanism – It refers to a system’s ability to recover from an anomaly. In software or processor architectures, it uses a specific address or routine to restore the system’s state. In mechanical engineering, it refers to a linkage (like a shaper machine) where the return stroke is faster than the cutting stroke.
Exception vector – It is a specific memory address pointing to an exception handler, a routine that forces a processor to suspend its current execution and respond to an error, hardware interrupt, or system event. These addresses are organized sequentially in a memory-mapped structure known as an exception vector table.
Excess air coefficient – It is the ratio of the actual quantity of air supplied to a combustion system against the theoretical (stoichiometric) air needed to burn the fuel completely.
Excess capacity – It is the difference between a system’s maximum potential output and its current actual production. It represents the untapped capability of machinery, facilities, or personnel to produce more goods or provide more services under existing resources.
Excess carrier density – It refers to the concentration of charge carriers (electrons and holes) in a semi-conductor which exceeds the base-line thermal equilibrium concentration. It is typically created by external energy sources like light, lasers, or electrical injection.
Excess carriers – These are additional electrons and holes generated in a semi-conductor beyond its baseline thermal equilibrium. They are introduced by external stimuli like light (photons), thermal energy, or an applied electrical bias, and are the fundamental basis for the operation of electronic and opto-electronic devices.
Excess cement – It refers to cement paste content which exceeds the optimal mix design. In concrete, it can cause excessive heat during curing (which leads to thermal cracking), increased drying shrinkage, and decreased workability.
Excess energy – It is normally defined as the quantity of energy generated, consumed, or produced which exceeds what is needed, utilized, or anticipated. It represents a surplus or waste, normally applied to energy systems producing more electricity than necessary, or chemical reactions releasing extra heat.
Excess Gibbs energy – It is the difference between the actual Gibbs free energy of a real liquid mixture and the Gibbs free energy it would have if it behaved as an ideal solution at the same temperature and pressure. It measures molecular deviations from ideality. It serves as a foundational bridge in chemical engineering, mainly used to calculate activity coefficients, which are necessary for predicting vapour-liquid equilibrium (VLE) and designing distillation columns or extraction processes.
Excess heat generation – It refers to the unintended production or accumulation of thermal energy beyond what a system is designed to handle or operate at. This mainly occurs as an energy by-product of inefficiencies (such as electrical resistance or friction) or as heat output exceeding what a system can safely dissipate.
Excessive leakage – It is the unintentional escape of mass (fluid / gas) or electrical current beyond pre-defined, safe, or efficient tolerances. It represents a functional failure that compromises system efficiency, component lifespan, or operational safety.
Excess metal – It refers to the unneeded material on a raw work-piece which is to be removed through metal machining (subtractive manufacturing) or trimmed after casting processes.
Excess oxygen – It refers to the unburned oxygen which remains in the exhaust gas after a combustion process, or the extra oxygen supplied to a system beyond the exact stoichiometric requirement. It is used as a critical metric to ensure complete combustion, protect equipment, or maintain optimal biological processes.
Excess oxygen ratio – It is the proportion of actual oxygen supplied to a system compared to the theoretical quantity needed for complete reaction or combustion. This term is mainly applied to combustion and fuel cells to optimize efficiency and prevent system failure.
Excess pore pressure – In geotechnical engineering, it is the quantity of pressure in the water-filled gaps between soil particles which rises above normal, steady-state hydrostatic pressure. It is mainly generated by rapid external loading, such as construction, seismic vibrations, or cyclic wave action.
Excess pore pressure dissipation – In geotechnical engineering, it is the gradual process where water trapped in soil pores escapes because of an applied load. As water drains, the temporary pressure it carries transfers to the solid soil particles, resulting in soil volume reduction (consolidation) and increased soil strength.
Excess pore water pressure – It is the temporary, localized increase in ground-water pressure above the normal hydrostatic level. It occurs when saturated soils are subjected to rapid loading, vibration, or seismic forces, and the trapped water cannot drain quickly enough, temporarily reducing the soil’s strength and stability.
Excess reactant – It is a substance present in a quantity higher than what is stoichiometrically needed to completely consume the limiting reactant. While the limiting reactant determines the maximum quantity of product that can be formed, the excess reactant is only partially consumed and remains in the mixture after the reaction concludes.
Excess slurry – It refers to the additional volume of a liquid-solid suspension (like cement or drilling mud) pumped into a system beyond the exact calculated volume. This buffer ensures operations succeed despite unpredictable void spaces, pipe friction, or settling.
Excess stress – It refers to internal or applied mechanical loads that exceed a material’s yield strength (or elastic limit). When this happens, it causes plastic (permanent) deformation, microscopic crack nucleation, and eventual metal fatigue or catastrophic component failure.
Excess supply – It refers to a state where the available resource or production capacity exceeds consumer demand. In project engineering, it is frequently tied to excess capacity (e.g., equipment or vessels overproducing compared to market need), while in power systems, it represents surplus electricity generation.
Excess temperature – It is the temperature difference between a heated solid surface and the saturation (boiling) temperature of the surrounding fluid.
Excess vacancy – It refers to a concentration of missing atoms (lattice defects) which exceeds the natural thermodynamic equilibrium. These are typically created through rapid cooling (quenching), severe plastic deformation, or additive manufacturing, and they considerably influence atomic diffusion, material strength, and electrical properties.
Excess zinc – It is the extra amounts of zinc which can accumulate on the steel because of chemical composition of the steel or the profile of the steel.
Excess wear – It is the gradual loss of material because of friction, abrasion, or other factors, needing regular inspections and maintenance to prevent equipment failure.
Exchangeable image file format – It is a standardized specification for storing metadata within digital image and audio files generated by cameras and smart-phones. It embeds technical details, such as camera settings, date / time, and GPS (global positioning system) location, directly into the file, allowing software to read and organize image information.
Exchangeable load – It refers to a modular unit, weight, or resource which can be detached, swapped, or replaced with another to alter a system’s function.
Exchange coefficient – It very frequently referred to as a heat transfer coefficient. It quantifies how effectively thermal energy moves between a solid surface and a fluid, or between two fluids. It measures the rate of heat exchange per unit of surface area per unit of temperature difference.
Exchange constant – It is also called exchange stiffness constant. It is a fundamental parameter which quantifies the strength of the quantum mechanical exchange interaction between neighbouring atomic spins in a magnetic material. It dictates how strongly a material’s microscopic magnetic moments ‘prefer’ to align parallel to each other, acting as an energetic penalty against non-uniform magnetization (e.g., spin waves, domain walls).
Exchange-correlation potential – It is the quantum-mechanical component in density functional theory (DFT) which accounts for all complex electron-electron interactions. It encapsulates the Pauli exclusion principle (exchange) and electron repulsion (correlation) so systems can be modelled accurately.
Exchange current – When an electrode reaches dynamic equilibrium in a solution, the rate of anodic dissolution balances the rate of cathodic plating. The rate at which either positive or negative charges are entering or leaving the surface at this point is known as the exchange current.
Exchange current density – It is the rate of charge transfer per unit area when an electrode reaches dynamic equilibrium (at its reversible potential) in a solution. i.e., the rate of anodic charge transfer (oxidation) balances the rate of cathodic charge transfer (reduction).
Exchange degree – It refers to the extent of ion exchange which occurs in zeolites, which affects their structural properties and surface characteristics, as demonstrated by changes in crystallinity and surface roughness with varying quantities of exchanged ions.
Exchange energy – It is the energy associated with the tendency of neighbouring magnetic moments in ferro-magnetic materials to orient parallel to each other, where any inhomogeneity of the magnetization increases the exchange energy.
Exchange fibre – It refers to the core optical fibre-optic cables which connect a local internet service provider (ISP) or telephone exchange to regional cabinets, hubs, or directly to premises. They are responsible for transmitting data as pulses of light at extreme speeds. Network engineers divide exchange fibre technologies into two main engineering setups, namely FTTC (fibre to the cabinet), and FTTP (fibre to the premises or full fibre).
Exchange membrane – It is normally known as an ion-exchange membrane. It is a semi-permeable polymer barrier designed to selectively transport specific dissolved ions while blocking other molecules. It acts as a crucial ion-conducting and reactant-separating layer in electro-chemical devices like fuel cells, electrolyzers, and water purification systems.
Exchange membrane pair – It refers to a combination of ion-exchange membranes used in microbial electrolysis and desalination cells (MEDCs) to improve energy efficiency and facilitate the removal of organics and recovery of nutrients during wastewater treatment. The performance of these pairs can impact energy consumption and ion migration in the treatment process.
Exchange operation – It refers to the process in energy geo-structures where heat is transferred between the ground and a superstructure, allowing for heating or cooling depending on climatic conditions. This operation can occur through either direct heating / cooling or combined with heat storage, depending on the thermal recharge capacity of the ground.
Exchange reaction – It is a process where ions or functional groups in two reacting molecules switch partners to form new products while maintaining electrical neutrality. The reaction relies on the formation of precipitates, gases, or weak electrolytes.
Exchange resin – It is the ion-exchange resin. It is an insoluble, cross-linked polymer matrix fabricated into microscopic beads. It is engineered to facilitate reversible chemical reactions by capturing unwanted, dissolved ions from a fluid stream and replacing them with desirable ions of a similar electrical charge. These resins act as the active filtering media in chemical engineering, separation science, and water treatment.
Exchanger, heat – It is the equipment used to efficiently transfer thermal energy between two or more fluids (liquids or gases) without allowing them to mix. It is frequently categorized by its structure, role, or working fluid. The transfer relies on conduction and convection across a physical barrier, normally a metal surface.
Exchanger tube – It is a cylindrical conduit used in a heat exchanger to transfer thermal energy between two fluids without allowing them to mix. Acting as the primary physical barrier and heat-transfer surface, it separates the ‘tube-side’ fluid from the ‘shell-side’ fluid. Exchanger tubes are critical components across process engineering, characterized by its design attributes and functions.
Excimer lamp – It is a specialized gas-discharge ultra-violet (UV) or vacuum ultra-violet (VUV) light source. It operates by producing spontaneous emission from excited dimers (excimers) or exciplexes. Unlike lasers, they do not use optical resonators and emit light diffusely rather than in a coherent beam.
Excimer laser – It is a pulsed gas laser that emits high-power ultra-violet (UV) light. It operates through electrical discharge through a high-pressure gas mixture of noble gases (e.g., argon, krypton, xenon) and reactive halogens (e.g., fluorine, chlorine), which form temporary, highly energized molecules that emit deep-UV (ultra-violet) radiation.
Excitable media – These are chemical systems which maintain a stable steady state but can respond to perturbations above a critical threshold with excitation events, followed by a refractory period during which they are insensitive to further excitation. These media can show wave-like patterns of excitation when coupled spatially, allowing for reusable chemical processing systems.
Excitation – It refers to the process of energy being supplied to atoms, causing them to transition from a lower energy state to a higher energy state. It also refers to the process of applying an external voltage, current, or physical force to a system to activate it or produce a specific response.
Excitation condition – It refers to the application of an external force, voltage, stimulus, or boundary condition used to activate, power, or test a system. The exact definition and function vary considerably depending on the engineering discipline.
Excitation density – It is frequently referred to as excitation power density or energy density. It quantifies the concentration of external energy (such as light or electron beams) applied to a specific volume or area of a material. It is the key metric used to evaluate how a system responds to stimulation, driving phenomena like luminescence, charge-carrier generation, and nonlinear optical effects.
Excitation energy – It is the specific quantity of energy needed to move a system (such as an electron in an atom) from its lowest energy state (ground state) to a higher, unstable energy state (excited state).
Excitation force – It is any dynamic, external force or stimulus applied to a physical system (like a machine, building, or structure) which causes it to vibrate or move. It initiates structural response, dictating how the system reacts in terms of frequency, amplitude, and resonance.
Excitation frequency – It is the rate at which an external force, vibration, or stimulus is cyclically applied to a system. Measured in hertz (Hz) or cycles per second, it drives the system’s dynamic response and determines how energy transfers through a structure, mechanical assembly, or circuit.
Excitation index – It is the ratio of the intensities of two selected spectral lines of an element having widely different excitation energies. This ratio serves to indicate the level of excitation energy in the source.
Excitation laser beam – It is a focused, highly coherent light source used to illuminate a material or sample. Its main purpose is to impart energy, driving atoms or molecules into higher energy states to trigger specific optical or chemical responses.
Excitation light – It is the specific wavelength of energy used to illuminate a sample in order to stimulate electrons and raise them to a higher energy state. This fundamental principle drives analytical techniques like fluorescence, spectroscopy, and flow cytometry.
Excitation method – It defines the technique used to supply a regulated, continuous direct current (DC) to the field windings of a generator or to apply dynamic forces / stimuli to structural and electrical systems.
Excitation potential (X-ray) – It is the applied potential on an x-ray tube needed to produce characteristic radiation from the target.
Excitation source – It refers to the origin of the energy or stimulus applied to a system to produce a specific response, voltage, or measurement. It is the light source used to stimulate a sample, typically for fluorescence or Raman measurements, which can include lasers, narrow-band light-emitting diodes (LEDs), ultra-violet lamps, and high-pressure arc lamps. These sources generate light through mechanisms such as stimulated emission and provide concentrated energy with specific wave-lengths.
Excitation spectrum – It is a plot of fluorescence or luminescence intensity against varying excitation wave-lengths, while holding the emission wave-length constant. It reveals which light wave-lengths are most efficiently absorbed by a material to produce light emission, guiding the design of optical and sensing systems.
Excitation volume – It is the volume within the sample in which data signals originate.
Excited electron – It is a bound electron which has absorbed sufficient energy to jump from its stable base energy level (ground state) to a higher, less stable energy level. This concept is fundamental to semi-conductor engineering, opto-electronics, and telecommunications.
Excited state – It refers to a high-energy, unstable state of an atom or electron in a metal, caused by absorbing external energy (e.g., heat or light). Electrons move from their lowest energy state (ground state) to higher, more distant electron orbitals. These metastable states are crucial in spectroscopic material analysis.
Excited vibration – It occurs when a mechanical or structural system is continuously driven by an external, time-varying force, moment, or displacement. These vibrations are classified broadly into two categories namely forced vibration and self-excited vibration.
Exciter – It is a device which supplies direct current (DC) to the field windings of a larger electrical machine (like a generator or alternator). By creating the necessary magnetic field, the exciter enables the main equipment to induce voltage and generate electrical power.
Exciting frequency – It is also called excitation frequency. It is the rate at which an external force, vibration, or stimulus is applied to a mechanical or structural system. Measured in hertz (Hz) or revolutions per minute (rpm), it drives the system’s forced response.
Exciton binding energy – It is the energy needed to dissociate an exciton (an electrically neutral, bound state of an electron and an electron hole) into its constituent free charge carriers. It is the stabilization energy resulting from Coulomb electrostatic attraction between the two particles.
Exclusion chromatography – It is normally called size-exclusion chromatography (SEC). It is a separation technique which sorts molecules in a fluid mixture based strictly on their size and hydrodynamic volume. It is widely used to analyze molecular weight distributions, and characterize industrial polymers.
Exclusive economic zone – It is a maritime area extending up to 200 nautical miles (370 kilometers ) offshore, where a state has sovereign rights to explore and exploit natural resources, including the water column, seabed, and its subsoil.
Excrescence – It is a term used by some tribologists describing micro-extrusions on friction surfaces that lead to localized welding.
Executable code – It is the low-level machine code or byte-code which a computer’s central processing unit (CPU) can directly process and run. Unlike human-readable source code, executable code is the final, translated version of a programme generated by compilers, assemblers, or interpreters, ready to perform specific instructions.
Executable specification – It is a system requirement which is written in a standardized, human-readable format, but is also capable of being run as an automated test. It acts as a single, unambiguous ‘living document’ which links plain-English business rules directly to the actual functioning code.
Executing agency – It is the main entity, institution, or organization responsible for the overall execution, management, and supervision of a project. They are accountable to the funding source for achieving project goals, managing funds, and ensuring compliance with technical specifications.
Execution cycle – It is also known as the instruction cycle. It is the fundamental operational process of a central processing unit (CPU), during which it repeatedly fetches machine instructions from memory, decodes them, and carries them out. This sequence dictates how hardware processes data, repeating millions or billions of times per second.
Execution engine – It is the core software component responsible for taking compiled or abstracted code (like byte-code, or workflow graphs), translating it into native machine instructions, and running it on hardware. It handles memory allocation, thread management, and the actual processing logic of the application.
Execution phase – It is the core implementation stage where finalized designs and approved project plans are transformed into tangible deliverables. It is typically the longest and most resource-intensive phase, encompassing detailed engineering, procurement, construction, fabrication, testing, and commissioning, culminating in project handover.
Execution time – It is the quantity of time needed to fully complete the execution of a task, assuming no other tasks are competing for resources. It is the total quantity of time a system, processor, or algorithm takes to complete a specific task or process from start to finish. It is a n important performance metric for evaluating system efficiency and hardware capabilities.
Exemplary system – It refers to a standard, prototypical, or highly representative implementation of a complex system designed to serve as a model for analysis, testing, or broader development. It provides a baseline architecture with concrete engineering choices which effectively solve a given problem.
Exemption level – It is the legally defined threshold of radioactivity (in activity concentration or total activity). Below this value, radioactive materials or sources are free from regulatory control and do not need formal notification, authorization, or licensing.
Exempt solvents – These are solvents which are not subject to air pollution legislation. Several alcohols, esters, some ketones, and mineral spirits are exempt. Aromatic and some ethylenic compounds are not exempt, and their use as solvents is hence subject to regulation.
Exergetic efficiency – It measures how effectively a system converts available energy into useful work. Unlike standard energy efficiency, it accounts for both the quantity and the quality of energy, assessing how much exergy is preserved relative to idealized reversible conditions.
Exergetic life cycle assessment – it is a methodology which integrates exergy analysis with standard life cycle assessment (LCA). It quantifies both the quantity and quality of energy and materials needed across a product’s entire life cycle, from raw material extraction to end-of-life disposal, while specifically accounting for exergy losses and irreversibilities. In traditional life cycle assessment, energy is evaluated purely based on quantity (e.g., joules or watt-hours consumed). Exergetic life cycle assessment (ExLCA) refines this by utilizing the fundamental concept of exergy, which is the maximum theoretical useful work a system can perform as it comes into thermodynamic equilibrium with its surrounding environment.
Exergo-economic analysis – It is an integrated approach which examines the relationship between thermodynamic inefficiencies and the cost of energy conversion systems, involving the costs of product and fuel streams as well as total capital and operational expenses.
Exergy – It is the maximum useful work (or potential to do work) obtainable from a system as it reaches equilibrium with its environment (the dead state or reference environment) through reversible processes. It represents the ‘quality’ of energy, rather than just its quantity, and is a key metric for second-law thermodynamic analysis to improve system efficiency and identify energy losses.
Exergy analysis – It is a thermodynamic accounting technique that evaluates the performance of systems by measuring the ‘quality’ or maximum useful work potential of energy. Based on the second law of thermodynamics, it goes beyond basic energy analysis by pinpointing exactly where, why, and by how much energy is destroyed or lost.
Exergy, availability – Availability exergy is the useful work potential of a system, quantifying the maximum work which can be extracted as it undergoes a reversible process to reach thermodynamic equilibrium with its environment. It measures the usefulness of energy or matter in causing change and is a key parameter for analyzing thermal systems.
Exergy balance – It is an accounting method based on the second law of thermodynamics. It tracks the usable energy (work potential) entering, leaving, and being destroyed within a system. Unlike energy, which is conserved, exergy is consumed because of irreversibilities (like friction or heat transfer). Exergy balances are used to identify thermodynamic inefficiencies in thermal and mechanical systems, helping engineers figure out exactly where and how much useful work potential is lost.
Exergy balance equation – It is a thermodynamic tool used to quantify the maximum useful work potential of a system. Rooted in the second law of thermodynamics, it accounts for exergy inputs, outputs, and consumption (destruction), showing that unlike energy, exergy is consumed by irreversibilities. The equation is foundational for thermodynamic system analysis to identify where energy losses and inefficiencies occur.
Exergy concept – It is the maximum ability of a substance to perform work relative to its environment, reflecting its practical value when conditions are not in equilibrium. It quantifies the potential of matter to do work based on its parameters like pressure, temperature, and composition.
Exergy consumption – It is the loss of the useful work potential of a system during a real, irreversible process. Unlike energy, which is conserved, exergy is consumed when entropy is generated, representing wasted potential to perform mechanical work.
Exergy content – It is the maximum theoretical useful work obtainable from a system or energy stream as it reversibly comes into thermodynamic equilibrium with its surrounding environment. Unlike energy, which is strictly conserved, exergy acts as a measure of energy quality and is destroyed by irreversible processes like friction or heat transfer.
Exergy destruction – It is the loss of useful work potential in a system undergoing a thermodynamic process because of the internal irreversibilities. It represents the ‘unavailable energy’ which cannot be recovered as work. Frequently referred to as irreversibility or lost work, it highlights where energy efficiency is lost in equipment like compressors or turbines.
Exergy destruction rate – It is the rate at which useful work potential is lost because of the irreversibilities (like friction, mixing, or heat transfer) in a thermodynamic process. It represents the gap between perfect, reversible performance and real-world operation.
Exergy efficiency – It is a measure of how effectively a system converts available energy (exergy) into useful work or a desired product. It compares actual system performance against the theoretical maximum (ideal or reversible) performance, highlighting exactly how much energy potential is destroyed by irreversibilities. It is the parameter which gauges the effectiveness of a system in preserving its exergy during a physical process, with higher efficiency indicating lower irreversibility. It considers the exergy quantities which cross the system boundaries, including flow exergy associated with mass flux and exergy transfer related to energy quantities such as heat and work.
Exergy flow – It is the maximum theoretical useful work obtainable from a stream of matter or energy as it moves from its current state to a state of equilibrium with the surrounding environment (dead state). It measures both the quantity and quality of energy, representing the ‘useful’ portion which can be converted into work, rather than just the total energy content. Exergy flow includes physical exergy (temperature / pressure), chemical exergy (composition), potential, and kinetic components.
Exergy flow diagram – It is also known as a Grassmann diagram. It is a visual tool used to map the maximum useful work potential of energy as it moves through a system. Unlike standard energy flow diagrams, they clearly highlight exergy destruction (irreversibility) and trace where potential work is lost during processes.
Exergy flow rate – It is the useful work potential of a flowing stream of energy or matter as it enters or exits a system per unit of time. Measured in kilo-watts or mega-watts, it quantifies the ‘quality’ of energy based on its ability to do useful work relative to the environment.
Exergy input – It is the maximum quantity of useful work which can be extracted from an energy source or material stream as it is brought into complete thermodynamic equilibrium with its surrounding environment. It represents the true ‘quality’ or work potential of the energy entering a system. Unlike energy, which is conserved, exergy input is degraded or partially destroyed in every real process because of the internal irreversibilities (such as friction or heat transfer across a finite temperature difference).
Exergy loss – It is the measure of useful energy which is wasted or becomes unavailable to perform work because of the inefficiencies and irreversibilities in a system. It specifically represents exergy which is transferred across system boundaries (e.g., through rejected heat, exhaust, or escaping mass) rather than exergy permanently destroyed internally by entropy generation.
Exergy loss rate – It quantifies the rate of useful work potential lost during a thermodynamic process because of the irreversibilities, such as friction, unrestrained expansion, or heat transfer across a finite temperature difference. The exergy loss rate identifies exactly where and how much energy quality degrades.
Exergy method – It is a technique based on the second law of thermodynamics. It quantifies the true ‘quality’ of energy by determining the theoretical maximum useful work a system can produce as it comes into equilibrium with its environment. Unlike conventional energy balances, which only account for energy quantity (conserving energy), the exergy method pinpoints where and how much useful work potential is destroyed (lost) because of the irreversibilities like friction, mixing, and heat transfer.
Exergy price – It is also called or unit exergy cost. It is the monetary value assigned to resources based on their exergy values, their maximum potential to perform useful work. This metric aligns financial costs with the actual physical quality of the resources, rather than just raw energy content.
Exergy quasi-unsteady flow – It refers to an analysis method which treats a changing fluid flow process (unsteady / transient) as a series of discrete, steady-state, or equilibrium steps over time, specifically to evaluate the maximum useful work potential (exergy). It is frequently used when the time-dependent changes in fluid properties (velocity, pressure, temperature) are slow enough that steady-state equations can be applied within small time steps, but the overall process needs tracking the accumulated changes.
Exergy rate – It measures the maximum useful work potential a system can produce per unit of time as it reaches equilibrium with its environment (the dead state). It is measured in power units like watts or mega-watts and is mainly used to evaluate process efficiency.
Exergy utilization – It is a thermodynamic metric which measures how effectively a system converts the actual useful work potential (exergy) of a resource into the desired output. Unlike standard energy efficiency, which treats all energy equally, exergy utilization assesses the quality and usefulness of energy.
Exfiltration – It is the unintentional or uncontrolled leakage of materials, such as water, sewage, or air, out of a designed system into the surrounding environment. It represents a failure in system containment (e.g., pipes, buildings), and is the opposite of infiltration (inward leakage) or inflow.
Exfoliated graphene – It is a form of graphene produced by peeling or separating individual, single-atom-thick layers of carbon from bulk graphite. Since graphite is made of these layers stacked on top of each other, the exfoliation process works by breaking the weak van der Waals forces between the sheets.
Exfoliation – It is the corrosion which proceeds laterally from the sites of initiation along planes parallel to the surface, normally at grain boundaries, forming corrosion products which force metal away from the body of the material, giving rise to a layered appearance. It is normally associated with wrought aluminum alloys. In case of refractories, it is the property possessed by certain materials, e.g., vermiculites, hydro-biotites, when submitted to sudden heating, to expand permanently in a direction parallel to the C-axis, forming a laminar texture.
Exhaust air-flow rate – It is the volume or mass of air expelled from a space or system over a specific time. Important for HVAC (heating, ventilation, and air conditioning) and industrial ventilation, it ensures the safe removal of contaminants, moisture, and heat while maintaining proper indoor air quality and room pressurization.
Exhaust back-pressure – It is the resistant pressure which exhaust gases encounter as they exit an engine to the atmosphere. It is the cumulative effect of hydraulic resistance from components like pipes, catalytic converters, and mufflers. Excessive back-pressure forces the engine to perform extra pumping work, hindering overall power and efficiency.
Exhaust condition – It describes the state of waste gases (temperature, pressure, and chemical composition) or the physical / operational health of an exhaust system. It evaluates how efficiently an engine processes combustion by-products while managing back-pressure, thermal loads, and environmental factors.
Exhaust connection – It refers to the mechanical junction or joint which links different segments of an exhaust system. These connections channel high-temperature, toxic gases away from an engine or process (like a combustion chamber or industrial tool) toward a safe disposal point while managing thermal expansion, vibrations, and structural stress.
Exhaust cooling water – It refers to the circulating or injected water used to lower the temperature of hot exhaust gases and steam. It absorbs extreme thermal energy, prevents component degradation, dampens engine noise, and facilitates condensation in closed-loop systems.
Exhaust duct – It is a specialized conduit or piping system designed to safely remove stale air, toxic gases, chemical fumes, smoke, or particulate matter from an indoor space to the external environment. It plays an important role in maintaining indoor air quality, thermal regulation, and structural safety.
Exhaust emissions – These refer to the gaseous and particulate by-products released into the atmosphere from an internal combustion engine after fuel combustion. These emissions typically include carbon di-oxide (CO2), water (H2O), carbon mono-oxide (CO), nitrogen oxides (NOx), and unburned hydrocarbons (HC).
Exhauster – It is a mechanical device, such as a fan, blower, or pump, designed to extract, expel, or pull air, gases, or particulate matter from an enclosed space or system.
Exhaust exergy – It is the maximum theoretical useful work an engine’s exhaust gas can produce as it comes into thermodynamic equilibrium with the surrounding environment. It evaluates the quality and potential usability of exhaust heat and pressure, rather than just its raw energy quantity.
Exhaust fan – It is a mechanical ventilation device which removes stale air, heat, moisture, fumes, or pollutants from an enclosed space and discharges them outdoors. It operates by creating negative pressure, which continuously draws out contaminated air and induces the passive intake of fresh air.
Exhaust flow – It refers to the movement, volume, and velocity of gases expelled from a system, such as an internal combustion engine or an HVAC (heating, ventilation, and air conditioning) unit. It is defined by its flow rate (volume over time) and is optimized to maximize efficiency while minimizing resistance, known as exhaust back pressure.
Exhaust flow rate – It is the volume or mass of gas, air, or fluid expelled from a system per unit of time. It is an important parameter for designing safe and efficient internal combustion engines, HVAC (heating, ventilation, and air conditioning) systems, and industrial exhaust hoods.
Exhaust fumes – It is also called exhaust gas. These fumes are the waste vapours and gases expelled from an internal combustion engine as a result of the fuel combustion process. This complex mixture is expelled into the atmosphere through a dedicated exhaust system.
Exhaust gas – It is also sometimes called flue gas or stack gas. It is the gas which emanates from th furnace because of the combustion of a fuel in the furnace. It contains the reaction products of fuel and combustion air and residual substances such as particulate matter (dust), and oxides of sulphur, nitrogen, and carbon.
Exhaust gas emissions – These are the by-products discharged into the atmosphere following the combustion of fuels (such as gasoline, diesel, or natural gas) in engines. These emissions are rigorously studied and monitored since incomplete combustion and high operating temperatures generate compounds harmful to human health and the environment.
Exhaust gas mixture – It is the complex combination of organic and inorganic compounds resulting from the combustion of fuel in an internal combustion engine or plant. It behaves thermodynamically as a unique ideal gas and consists of reaction by-products and excess air.
Exhaust gas recirculation – It is an emissions control technique which routes a portion of an engine’s exhaust gas back into the cylinders. By replacing some of the incoming fresh air with inert exhaust, the system dilutes the oxygen concentration and lowers peak combustion temperatures, considerably reducing harmful nitrogen oxide (NOx) emissions.
Exhaust gas recirculation (EGR) system – It is an emissions-control technique which diverts a controlled portion of an engine’s exhaust back into the combustion cylinders. By introducing inert exhaust gases, the system reduces oxygen concentration and lowers peak combustion temperatures, which considerably decreases the formation of harmful nitrogen oxides (NOx).
Exhaust gas recirculation (EGR) tube – It is a durable metal pipe which carries a portion of exhaust gases from the engine’s exhaust manifold to the intake manifold. It is a key part of the exhaust gas recirculation (EGR) system, reducing nitrogen oxides (NOx) by lowering combustion temperatures. These tubes are often flexible stainless steel with bellows to manage high temperatures (over 650 deg C) and vibrations.
Exhaust hood – It is the entry point of a local exhaust ventilation (LEV) system. It acts as a physical boundary or directional airflow device designed to capture, contain, and remove airborne contaminants, such as heat, steam, grease, dust, or toxic fumes, before they can disperse into the work-space.
Exhaust inlet – It is the opening or duct which captures spent gases or polluted air from a mechanism and directs them into an exhaust system. Depending on the field, it refers either to the engine port pulling gas from a cylinder or to the main intake of an industrial ventilation hood.
Exhaustive search – It is a method which evaluates all possible combinations of available variables for regression, frequently resulting in a substantial computational effort because of the large number of potential subsets formed.
Exhaust loss – It is the unrecovered thermal or kinetic energy lost when working fluids (like steam or combustion gases) are discharged into the environment or a condenser. It dictates overall thermal efficiency and is divided into leaving-velocity loss and exhaust pressure loss.
Exhaust manifold – It is a vital engine component which collects exhaust gases from multiple engine cylinders and funnels them into a single outlet pipe. It acts as a primary heat-resistant conduit, optimizing gas flow to reduce backpressure while helping to channel toxic by-products out of the combustion chamber.
Exhaust method – It refers to the techniques and processes used to safely extract, treat, and route spent gases out of a system (such as an internal combustion engine) or to manipulate physical phenomena to improve overall machine efficiency.
Exhaust nozzle – It is an important engine component which accelerates the flow of hot exhaust gases to generate thrust. By converting thermal and pressure energy into kinetic energy, the nozzle dictates the exit velocity of the exhaust, directly driving the forward propulsion of the aircraft and spacecraft.
Exhaust opening – It is any designated outlet, aperture, or valve used to expel gases, heat, or pollutants from an enclosure, engine, or system. Depending on the field, it refers to a mechanical valve in an engine or a ventilation port in industrial / architectural design.
Exhaust outlet – It is the final discharge point in an exhaust system where air, gases, or by-products are expelled from a machine, engine, or facility into the atmosphere. It marks the transition where internal flows are safely vented and dispersed.
Exhaust pipe – It is a critical conduit which transports high-temperature, pressurized combustion gases from the engine to the atmosphere. It is designed to optimize engine performance, reduce exhaust back-pressure, route emissions through the catalytic converter, and minimize acoustic noise.
Exhaust pressure – It is very frequently referred to as exhaust back pressure. It is the resistance to the flow of combustion gases moving through an engine’s exhaust system. It represents the hydraulic resistance or pressure buildup the engine is required to overcome to expel spent gases into the atmosphere.
Exhaust product – It refers to the complex mixture of gases, particulate matter, and compounds, such as carbon di-oxide (CO2), water vapour (H2O), carbon mono-oxide (CO), and nitrogen oxides (NOx), discharged after fuel combustion. It also describes the hardware, like mufflers and catalytic converters, which guide, treat, and safely vent these waste products.
Exhaust stroke – It is the final phase of a four-stroke internal combustion cycle where the piston travels upward from the bottom dead centre (BDC) to the top dead centre (TDC) with the exhaust valve open. This action expels the burnt combustion gases out of the cylinder and through the exhaust manifold.
Exhaust system – It is a network of components which collects high-temperature, high-pressure gases from a combustion chamber, safely disposes of them, and minimizes noise, emissions, and back-pressure.
Exhaust temperature – It is also called exhaust gas temperature. It is the heat of the gases leaving an engine or heat engine. It is a critical diagnostic metric which indicates how hard the machine is working, its overall combustion efficiency, and whether components are experiencing dangerous thermal stress.
Exhaust valve – It is a component in an internal combustion engine which opens and closes to release burnt gases (exhaust) from the combustion chamber. It is one of the key components in the valve mechanism, alongside intake valves, which control the entry of fresh air or air-fuel mixture. The opening and closing of the exhaust valve are precisely timed by the camshaft, ensuring efficient engine operation.
Exhaust valve closing – In internal combustion engine, it defines the exact crankshaft angle when the exhaust valve fully shuts, sealing the combustion chamber. It typically occurs slightly after top dead centre (TDC) to utilize the momentum of escaping exhaust gases for maximum cylinder clearance.
Exhaust velocity – It is the speed at which propellant mass, or combustion gases, exit a rocket or jet engine’s nozzle, relative to the engine. It is the main metric determining how efficiently a propulsion system converts fuel into thrust and dictates a spacecraft’s ultimate speed capabilities.
Exit burr – It is the burr formed on the surface at which the cutting tool or its teeth leaves the work-piece.
Existence region – It defines the stress-strain domain where a material can be deformed by an applied force and fully return to its original size and shape once the load is removed. It is the foundation of safe, non-permanent structural and mechanical design. It also refers to the specific area in the pressure -temperature (P-T) plane where a pure substance is to be entirely in a particular phase, such as solid, liquid, or gas, and is defined by the boundaries of phase.
Existence theorem – It is a mathematical statement guaranteeing that a solution to a specific problem or equation exists, without necessarily providing a method to find it. It serves as a foundational validation to ensure that dynamic models are stable, predictable, and physically possible to solve before running complex simulations.
Exit angle – It is the specific geometric angle at which a drill bit, cutting tool, fluid, or mechanical component leaves a surface or passage. Since definitions vary by field, it is used to optimize performance in machining, fluid dynamics, trench-less drilling, and turbo-machinery.
Exit burr – It is an unwanted, raised ridge or deformed edge of material left on a work-piece at the exact point where a cutting or shaping tool (like a drill bit, milling cutter, or saw) finishes its cut and exits the material.
Exit criteria – These are predefined conditions or requirements which is to be met before a specific project phase, design process, or testing iteration can be officially declared complete and ready to move to the next stage. They serve as a quality gate to prevent unfinished or low-quality work from progressing downstream.
Exit density – It refers to the concentration of individuals in proximity to exits during evacuation scenarios, which considerably influences decision-making and movement behaviour in emergency situations.
Exit diameter – It refers to the physical measurement of an opening (such as a nozzle, pipe, or drilled hole) at the point where a fluid, gas, or physical object leaves the system. It is a critical parameter used to calculate flow rates, pressure drops, and propulsion thrust.
Exit flow – It refers to the state, velocity, and behaviour of a fluid (liquid or gas) as it leaves a confined system, boundary, or device. It is important for determining system efficiency, thrust generation, and energy losses.
Exit guide – It is a device used to maintain the alignment and prevent buckling of the metal as it leaves the rolls. It ensures the rolled material exits the pass line smoothly, preventing potential defects.
Exit loss – It is a minor energy loss which that occurs when a fluid leaves a confined pipe or channel and enters a larger, unconfined space (such as a reservoir) or a different flow regime. It is caused by the sudden expansion and dissipation of the fluid’s kinetic energy.
Exiting stream – It refers to any fluid or substance (liquid, gas, or solid suspension) which leaves a specific component or unit within a larger system at a defined temperature, pressure, and flow rate. It is a fundamental concept in mass and energy balance calculations.
Exit Mach number – It is the ratio of a fluid’s flow velocity to the local speed of sound at the discharge point of a flow device (like a nozzle, turbine, or engine exhaust). It defines the compressibility and expansion state of the fluid as it leaves a boundary.
Exit plane – It refers to the cross-sectional boundary where fluid, gas, or material leaves a physical device or opening. It is an important theoretical station used to define fluid dynamics or machining parameters.
Exit portal – In civil and tunneling engineering, it is the opening, mouth, or transition structure where a tunnel, mine, or underground passage ends and emerges into the open air. It frequently needs specialized structural reinforcement to prevent rock collapse and control airflow.
Exit pressure – It refers to the static pressure of a fluid, gas, or vapour at the exact point it leaves a flow device, such as a pipe, valve, or converging-diverging nozzle. It refers to the pressure at the exit of a nozzle, which is critical in determining the flow behaviour relative to atmospheric pressure. It influences whether the flow is under expanded, perfectly expanded, or over expanded, hence affecting performance and thrust.
Exit side – It refers to the side of a material where the kerf width is measured after a cutting process, indicating the characteristics of the cut at the end of the operation. It very frequently identifies the location where a drill emerges from the ground, the surface where a cutting tool finishes its pass, or an architectural fire-rated exit.
Exit strip speed – In a hot strip mill, it refers to the velocity of the steel strip as it leaves a particular stand or stage of the rolling process. This speed is a critical parameter which influences factors like strip tension, flatness, and the overall quality of the final product.
Exit swirl – It is also residual swirl. It refers to the rotational, tangential motion of a fluid as it leaves a component (like a turbine, pump, or nozzle) and moves into the next stage. It represents left-over kinetic energy which does not convert into useful work or thrust.
Exit temperature – It is the temperature of a fluid, gas, or material as it leaves a specific process, component, or system. It is an important parameter used to evaluate thermal efficiency, ensure equipment safety, and control the quality of manufactured goods.
Exit velocity – It refers to the speed at which a fluid (liquid or gas) passes out of a designated boundary, such as a nozzle, pipe, flare tip, or duct. It is used to calculate mass flow rate, thrust, and energy losses.
Exit zone – In architecture and occupational safety, it is a heavily regulated pathway. As per the standard, an exit is a completely enclosed, fire-rated passage, such as an exit stairwell or exterior door, which physically separates occupants from fire and smoke. The exit zone is where a safe, protected route terminates and discharges into a public way or open space. In the natural gas and energy industries, an exit zone defines a geographical or operational boundary within a gas pipeline network. It is used to allocate pipeline capacity and manage the flow of gas delivered to consumers or distribution organizations.
Exo-electron emission – It is a, normally low-energy, electron emission from the surface of solids (typically insulators or metals) occurring after pre-treatment, such as mechanical deformation (scratching, abrading) or irradiation (ionizing, ultra-violet), rather than from high temperature alone. It represents the relaxation of an unstable state created by the stimulation, frequently emitting electrons when heated or illuminated.
Exogenic deposits -These are ore deposits formed because of the exogenic processes. Ore deposits are grouped as exogenic if their origin is because of the surficial processes such as weathering or shallow sedimentation with little or no relation to tectonics.
Exogenic processes – These are the processes which operates over the surface and are responsible for the formation of ore deposits. These processes include sedimentary precipitation, residual concentration processes, supergene enrichment process and volcanic exhalative processes.
Exogenous disturbance -It refers to any external influence, signal, or environmental factor which affects a system’s performance or dynamics. Because it originates outside the system boundary, it cannot be directly controlled at its source but is to be mitigated or compensated for by the system’s controller.
Exogenous factor – It is any external variable or outside influence which affects a system but is not determined or controlled by that system. These independent inputs drive or stress the system, while the internal responses are known as endogenous factors.
Exogenous inclusion – It is an inclusion which is derived from external causes. Slag, dross, entrapped mould materials, and refractories are examples of inclusions which are classified as exogenous. In majority of the cases, these inclusions are macroscopic or visible to the naked eye.
Exogenous variables – An exogenous variable in a statistical model refers to a variable whose value is determined by influences outside of the statistical model. An assumption of statistical modelling is that explanatory variables are exogenous. When explanatory variables are endogenous, problems arise when using these variables in statistical models.
Exo-process – It is an electric arc cutting process. Similar to flux-cored processes, it uses a consumable tubular electrode and a specially designed gun which feeds high-speed compressed air to the arc. The air flow functions to push molten metal from the gouge cavity, to constrict the arc for more precise control, and to cool the electrode. The system can be adapted to conventional gas metal arc welding equipment (it needs a direct current constant voltage power source and a conventional wire feeder). The velocity of the air flow at the arc is the key factor for straight cutting. A 1.5 milli-meter wire size can cut up to 6 milli-meters thick carbon steel. Speed and edge cut quality on most commercial metals and alloys is good, particularly for sheet metal thicknesses. Gouge quality on carbon steels is also good. The process is well suited for automated equipment, in that high travel speeds can be attained. An obvious benefit of the process is that it can be mounted on a gas metal arc dual-wire feed system to provide the operator with a multifunctional welding and cutting unit
Exotherm – It is the liberation or evolution of heat during the curing of a plastic product.
Exothermic – It is characterized by the liberation of heat.
Exothermic atmosphere – it is a gas mixture produced by the partial combustion of a hydrocarbon gas with air in an exothermic reaction. It is also known as exogas.
Exothermic brazing – It is a highly specialized processes where braze filler metals are melted using exothermic reactions between two metals, a metal oxide and a metal or an inorganic non-metal. It a process which utilizes the heat produced in a solid-state chemical reaction to melt a conventional filler metal or to produce molten filler metal as a product of the reaction.
Exothermic compounds – These are those compounds which generate enough heat to melt conventional filler metals. These compounds have been developed for iron alloys, copper alloys, and refractory metals. Aluminum compounds which react and produce a heterogeneous filler metal can be used to join aluminum alloys.
Exothermic gas atmosphere – It is a reducing gas atmosphere used in sintering and produced by partial or complete combustion of a hydrocarbon fuel gas and air. Maximum combustibles are around 25 %.
Exothermic oxidation – It is a thermal reaction which involves the oxidation of a substance, such as carbon, releasing energy in the form of heat, as seen in the reaction of carbon with oxygen to produce carbon di-oxide.
Exothermic peak – It is the point on a thermal analysis graph, like those from differential scanning calorimetry (DSC), where a material rapidly releases energy in the form of heat. This peak indicates that a physical or chemical change has occurred, such as [crystallization] or [polymer curing].
Exothermic process – It is a thermodynamic process or reaction which releases energy from the system to its surroundings. It is normally in the form of heat, but also in a form of light (e.g., a spark, flame, or flash), electricity (e.g. a battery), or sound (e.g., explosion heard when burning hydrogen).
Exothermic reaction – It is a reaction which liberates heat, such as the burning of fuel or when certain plastic resins are cured chemically.
Exothermic soldering – It is a highly specialized processes where solder filler metals are melted using exothermic reactions between two metals, a metal oxide and a metal or an inorganic non-metal.
Exothermic welding – It is also known as exothermic bonding, thermite welding (TW), and thermit welding. It is a welding process which uses molten metal to permanently join the conductors. The process employs an exothermic reaction of a thermite composition to heat the metal, and needs no external source of heat or current.
Exotic alloys – These are zirconium, niobium, hafnium, and tantalum products. Materials with high alloy content are also known as super alloys or exotic alloys; These materials offer improved performance properties including excellent strength and durability, and resistance to oxidation, corrosion and deforming at high temperatures or under extreme pressure. Because of these properties, exotic alloys make the best spring materials for demanding working conditions, which can be encountered across different industry sectors, including the automotive, marine and aerospace sectors as well as oil and gas extraction, thermal processing, petrochemical processing and power generation.
Expandable tube – It is a type of casing with a thinner wall compared to conventional casing, allowing for a larger internal diameter, but resulting in reduced collapse strength because of the potential non-uniform expansion and variations in wall thickness. It is mainly used in applications such as intermediate strings or liners during well drilling.
Expanded area ratio – It is the ratio of the total expanded surface area of all propeller blades to the total area of the propeller disk (the sweeping circle described by the rotating blades). It is an important hydro-dynamic parameter used to determine propeller efficiency and prevent cavitation.
Expanded austenite – It is also known as the S-phase. It is a metastable, nitrogen or carbon super-saturated solid solution formed in austenitic stainless steel. It is created through low-temperature thermo-chemical surface treatments (such as nitriding), which cause the crystal lattice to expand dramatically because of the massive interstitial intake of atoms.
Expanded clay aggregate – It is also known as light-weight expanded clay aggregate (LECA). It is a light-weight aggregate created by heating natural clay in a rotary kiln at extremely high temperatures (1,100 deg C to 1,300 deg C). This rapid heating expands the clay into a durable, porous, honey-combed ceramic pellet with a hard outer crust.
Expanded graphite – It is a highly porous, low-density carbon material produced by treating natural flake graphite with intercalants (like sulphuric acid and oxidizers) and exposing it to rapid heat. This thermal shock triggers a massive expansion, creating worm-like structures with immense surface area, thermal resilience, and electrical conductivity.
Expanded poly-styrene – It is a lightweight and rigid foam material. It is a material of choice for the packaging and construction industry. It provides cost-effective solutions and energy-efficient insulation. It also acts as a cushion transport packaging material for shock-sensitive goods. It is a generic term for polystyrene and styrene copolymers, supplied as a compound with physical blowing agents and other additives which can be processed into low density foamed articles.
Expanded poly-tetra-fluoro-ethylene – It is a porous membrane derived from poly-tetra-fluoro-ethylene (PTFE) which retains several of poly-tetra-fluoro-ethylene’s unique properties while introducing new ones and addressing its limitations, particularly in strength under stress.
Expander process – It is a thermodynamic cycle or engineering method which utilizes an expansion turbine (turbo-expander) to reduce the pressure of a high-pressure gas. This rapid expansion extracts potential heat and pressure energy, converting it into mechanical work while causing the gas temperature to drop considerably. The expander process mainly drives major applications like cryogenics, natural gas liquids (NGL) recovery, and power generation.
Expander-compressor – It is also known as a turbo-expander. It is a coupled turbo-machine in which a high-pressure gas expands through a turbine to generate mechanical work. This work is directly used to drive a centrifugal compressor mounted on the same shaft, effectively recycling extracted energy to recompress process gases or provide industrial refrigeration.
Expanding – It is a process used to increase the diameter of a cup, shell, or tube. Expanding can be done by drifting with sectional expanders or by rolling with three-roll expanders.
Expanding crack – It is frequently called crack propagation. It refers to the growth, extension, or widening of an existing defect or fissure within a material over time. This phenomenon compromises structural integrity and can ultimately lead to material or structural failure.
Expanding gate valve – It is also called double expanding gate valve. It is a gate valve comprised of a separate gate and segment which, as the valve operates the gate and segment, move without touching the seats, permitting the valve to be opened and closed without wear. In the closed position, the gate and segment are forced against the seats. Continued downward movement of the gate causes the gate and segment to expand against the seats. When the valve reaches its full-open position, the gate and segment seal off against the seats while the flow is isolated from the valve body.
Expanding ring test – It is a procedure which applies internal pressure or radial force to a ring-shaped sample, frequently cut from pipe or tube, until it undergoes plastic deformation or breaks. It measures hoop / transverse yield strength and material ductility under tensile strain. The test evaluates the circumferential (hoop) tensile strength and deformation ability of a material. It is frequently used to assess pipe quality or investigate high-strain-rate behaviours.
Expansion bus – It is an electrical pathway and protocol used in computer engineering to connect the central processing unit (CPU) and main memory to peripheral devices. It allows users to improve system capabilities and upgrade hardware using add-on expansion boards like graphics processing units (GPUs) and sound cards.
Expansion chamber – It is a precisely tuned, acoustic exhaust component used in two-stroke engines to maximize volumetric efficiency. By harnessing sound waves, it artificially boosts engine power, effectively acting as an acoustic supercharger with zero moving parts.
Expansion coefficient – It refers to the measure of how much a solid material expands or contracts in response to changes in temperature. It can be estimated using a thermodynamic equation of state which relates the expansion coefficient to specific heat, density, and bulk modulus of the material.
Expansion factor – It is a dimensionless or fractional multiplier used to account for a change in volume, density, or rate.
Expansion flow – It typically refers to supersonic fluid expansion (aero-dynamics) or pipe expansion (fluid mechanics). It describes how gases or liquids accelerate and lose pressure as the cross-sectional area increases or as they turn around a convex corner.
Expansion joint – It is an assembly designed to hold parts together while safely absorbing temperature-induced expansion and contraction of building materials. They are normally found between sections of buildings, bridges, sidewalks, railway tracks, piping systems, ships, and other structures.
Expansion loop – It is a flexible, U-shaped or zig-zag section of pipe installed in long, straight pipe-line runs. Its main purpose is to safely absorb thermal expansion and contraction caused by temperature fluctuations. By adding this geometric loop, the pipe acts as a giant spring. Instead of transmitting extreme bending and compressive stresses which can buckle the pipe or damage connected equipment, the loop deflects elastically to absorb the movement.
Expansion, operator – Operator expansion is a method for representing the Fermi operator in a system’s electronic structure, which can be generalized for use in non-orthogonal basis sets, although it is computationally costly compared to other methods.
Expansion pressure – It refers to the force generated when a confined material expands, or the rapid rise in pressure caused by thermal or hydraulic expansion of trapped fluids. Its magnitude depends on the material’s expansion properties and the elasticity of the surrounding container or host medium.
Expansion process – It refers to the increase in volume of a substance, typically a gas, fluid, or solid, because of the changes in temperature, pressure, or physical manipulation. It is a fundamental concept used to convert thermal energy into mechanical work or to accommodate dimensional changes.
Expansion ratio – It is a dimensionless parameter defined as the ratio of a substance’s volume, area, or size after expansion to its initial state.
Expansion, sand – It refers to the rapid increase in volume of moulding sand, particularly silica sand, when heated by molten metal. This phenomenon is a critical factor in sand casting, as the expansion can create substantial compressive stresses in the mould, leading to casting defects.
Expansion scab – It is a surface casting defect which appears as a rough, irregular, and raised layer of metal, frequently with sand inclusions trapped underneath. It is characterized as a ‘skin’ of metal which has detached from the main casting surface and is normally found on the cope (top) surface or on vertical walls. Expansion scabs are mainly caused by the rapid, uneven expansion of sand mould materials, particularly silica sand, when heated by molten metal.
Expansion tank – It is also called expansion vessel. It is an important pressure vessel in closed-loop fluid systems, such as hydronic heating. It acts as a safety cushion to absorb the increase in water volume and pressure caused by thermal expansion. Since water is an incompressible liquid, heating it in a closed system causes a rapid and dangerous spike in pressure. The expansion tank safely manages this state using the engineering principles.
Expansion, thermal – It is the tendency of matter to increase in length, area, or volume, changing its size and density, in response to an increase in temperature (normally it excludes phase transitions).
Expansion turbine – It is also called turboexpander. It is a centrifugal or axial-flow turbine which expands high-pressure gas to produce mechanical work while considerably reducing the gas temperature. It is used to generate refrigeration for industrial processes, such as natural gas processing and air liquefaction, or to drive compressors / generators.
Expansion unit – It typically refers to a peripheral hardware device attached to a computer or main system to add extra features, storage, or processing capabilities. The term can also refer to physical changes driven by temperature, such as the thermal expansion of materials.
Expansion valve – It is a thermodynamic device that restricts fluid flow to rapidly reduce its pressure. In HVAC (heating, ventilation and air conditioning) and refrigeration, it serves as the important dividing line between the high- and low-pressure sides of the system, converting high-pressure liquid refrigerant into a low-pressure, cold mixture of liquid and vapour.
Expansive agent – It is an admixture added to concrete or mortar which induces controlled expansion during hydration. This expansion is specifically designed to offset or minimize the natural volumetric shrinkage of concrete, preventing structural cracking and mitigating the formation of voids.
Expansive cements – These are hydraulic cements which expand slightly during the early hardening period after setting. Expansive cement contains portland cement, anhydrous tetra-calcium-tri-alumino-sulphate, calcium sulphate, and uncombined calcium oxide (lime). Expansive cement is used to make shrinkage-compensating concrete which is used (i) to compensate for volume decrease due to drying shrinkage, (ii) to induce tensile stress in reinforcement, and (iii) to stabilize long term dimensions of post tensioned concrete structures. One of the major advantages of using expansive cement is in the control and reduction of drying shrinkage cracks.
Expansive clay – It is also called shrink-swell soil. It is a type of clay soil which experiences substantial volume changes, swelling when absorbing moisture and shrinking when drying. Driven by specific minerals like montmorillonite, this cyclical expansion can exert immense upward pressure, frequently causing structural damage to foundations, pipes, and roads.
Expansive clay soils – These are clay-rich soils which undergo substantial volume changes (shrinking and swelling) in response to moisture fluctuations. When wet, they absorb water and expand dramatically; when dry, they lose moisture, shrink, and crack.
Expansive materials – These materials typically refer to either geotechnical soils (clays which swell when wet and shrink when dry) or chemical admixtures (additives used in concrete to offset shrinkage).
Expansive reaction – It refers to an internal chemical or physical process within a material which causes macroscopic volume expansion. In structural and materials engineering, this very frequently pertains to concrete where internal swelling forces, frequently caused by moisture and chemical interactions, lead to cracking and structural degradation.
Expansive soils – These are clay-rich soils which experience substantial volume changes (swelling and shrinking) in response to moisture fluctuations. When they absorb water, they expand and when they dry out, they shrink, leading to severe structural instability and ground movement.
Expectation – It is the expected or mean value of a random variable, or function of that variable such as the mean or variance. Exponential: A variable raised to a power of ‘x’. The function F (x) = (a)x is an exponential function.
Expectation-maximization (EM) algorithm – It is an iterative numerical technique used to find maximum likelihood estimates (MLE) or maximum A Posteriori (MAP) estimates for model parameters. It is specifically designed for situations where data is incomplete or involves latent (unobserved) variables.
Expectation over transformation – It is an advanced machine learning training technique used to create adversarial examples which are robust to real-world modifications, such as changes in lighting, viewpoint, or rotation. It works by optimizing a perturbation which remains adversarial across a whole distribution of transformations, rather than just on a single input image.
Expected life-time – It is the predicted duration or total amount of usage a product, component, or system is anticipated to function effectively before reaching the end of its operational life. It is calculated using design data, statistical modeling, and reliability testing. Engineers measure expected life-time through a few standard parameters.
Expected monetary value – It is a statistical risk management technique which calculates the average financial outcome of a decision under uncertainty. It quantifies the monetary impact of potential hazards, delays, or opportunities by multiplying each outcome’s financial value by its probability of occurrence.
Expected output – It refers to the targeted, tangible, or measurable results (products, services, or data) which a system, process, or task is designed to produce from given inputs. It represents the desired, planned, or predicted performance metric, frequently contrasted with actual output to measure efficiency and quality.
Expected result – It is the predefined, predicted outcome of a test case, simulation, or process, outlining how a component, system, or software is going to behave under specific conditions. It serves as an objective benchmark for verifying which a design, product, or code fulfills its requirements and functions correctly.
Expected value – It is the theoretical long-term average or ‘centre of mass’ of a random variable’s possible outcomes, weighted by their probabilities. It acts as a foundational decision-making tool for calculating reliability, mean lifetime, expected costs, and optimal system design.
Expendable-mould casting – It is a manufacturing process where molten metal is poured into a single-use mould, typically made of sand, plaster, or ceramic, which is destroyed to remove the solidified part. This technique allows for complex geometries, intricate internal cavities, and high-temperature alloys, though it needs a new mould for every cast.
Expendable pattern – It is also called expendable mould. It is a pattern which is destroyed in making a casting. It is normally made of wax (investment casting) or expanded polystyrene (lost foam casting).
Expendable-pattern casting – It is also called expendable mould casting. It is also called lost foam process. The pattern used in this process is made from polystyrene (a light, white packaging material). Polystyrene foam is 95 % air bubbles, and the material itself evaporates when the liquid metal is poured on it. The pattern is made by moulding. The polystyrene beads and pentane are put inside an aluminum mould, and heated. It expands to fill the mould, and takes the shape of the cavity. The pattern is removed, and used for the casting process.
Expensive generator – It refers to systems which, while offering high efficiency or advanced technology, need huge capital and operational costs. These generators typically feature heavy metals, specialized magnetics, or complex construction, such as medium-speed permanent magnet synchronous generators (PMSG) in wind turbines or large-scale DC (direct current) generators needing copper commutators.
Experience curve – It is a strategic management concept stating that the total cost of producing a good or service systematically decreases by a constant percentage (typically 10 % to 25 %) every time the cumulative volume of production doubles.
Experience curve concept – It is a representation of technological progress which shows the decline in technology costs as a function of cumulative experience, incorporating learning processes such as learning-by-doing and upscaling.
Experimental aerodynamics – It is the branch of engineering focused on the empirical investigation of airflow around solid objects. It utilizes specialized facilities like wind tunnels and advanced instrumentation to measure aerodynamic forces, such as lift and drag, validate computational models, and uncover complex flow behaviours.
Experimental aluminum alloys – These are new or specialized metallic mixtures under development to improve mechanical properties, such as increased tensile strength, higher temperature resistance, or improved corrosion resistance over standard industrial grades. Engineered by combining aluminum with elements like magnesium, silicon, or copper, these alloys are designed for advanced aerospace and automotive applications needing lower weight, higher fatigue resistance, and better formability.
Experimental blast furnace – It refers to a specially designed and constructed blast furnace used for research, development, or testing purposes, rather than for industrial production. These furnaces are frequently smaller, simplified versions of industrial blast furnaces, allowing researchers to study specific aspects of the ironmaking process in a controlled environment.
Experimental category – It normally refers to a regulatory classification or a formalized methodology used to test unproven hypotheses, prototypes, and designs. Depending on the field, this concept spans from rigorous statistical product testing to the official certification of custom-built machinery which lacks standard type certificates. This category emphasizes the importance of controlled environments to isolate variables and get reliable results.
Experimental characterization -It is the process of using empirical testing and measurement to determine the physical, chemical, or mechanical properties of a material or component. Its main objective is to evaluate these properties under controlled conditions to validate designs, calibrate simulations, and ensure structural integrity.
Experimental data set – It is a structured collection of measurements, observations, or test results got by deliberately manipulating controlled variables in an experiment. It is used to empirically validate physical theories, train machine learning models, and evaluate the performance of engineering systems.
Experimental determination – It is the process of empirically measuring and evaluating specific parameters, properties, or behaviours of a physical system or material under controlled conditions. It is an important method used to validate theoretical models, establish material properties, and ensure designs meet practical safety and performance requirements.
Experimental equation – It is a mathematical expression derived from empirical data and statistical analysis. It is used to quantify relationships between physical variables when theoretical physics cannot fully describe the system. These equations are built by curve-fitting observed measurements and are highly specific to the testing conditions.
Experimental exploration – It is the process of conducting physical or simulated tests to investigate new methods, materials, or system behaviours. Rather than merely confirming a known hypothesis, it prioritizes discovering the unknown, expanding system understanding, and reducing uncertainty in early design phases.
Experimental fact – It is an empirically verified piece of data gathered through controlled testing, observation, or measurement. It serves as irrefutable proof used to validate theoretical models, evaluate physical phenomena, and confirm the real-world performance of a material or system.
Experimental finding – It is a discovered fact, parameter, or performance metric derived from a structured, empirical investigation. It serves to validate theoretical models, optimize physical systems, or test hypotheses under controlled, measurable conditions.
Experimental investigation – It is a systematic, controlled process used to test a hypothesis, validate theoretical models, or analyze the cause-and-effect relationship between specific variables. It typically involves isolating a system and manipulating parameters to measure the physical, mechanical, or operational performance of an engineered component.
Experimental layout – It refers to the structured physical arrangement of experimental units (e.g., physical test samples, pilot processes) and the defined sequence of tests used in a design of experiments (DOE) to evaluate how specific variables impact a system. The concept forms a fundamental bridge between mathematical modeling and practical execution, establishing exactly where, how, and in what order tests occur.
Experimental measurement – It is the quantitative comparison between a pre-defined standard and an unknown physical quantity (the measurand). It is the empirical process of collecting, quantifying, and analyzing data from physical phenomena or engineering systems under controlled conditions.
Experimental model – It refers to a physical, scale, or mathematical representation of a system used to validate theories, test prototypes, and observe real-world performance. It serves to optimize designs, minimize risks, and bridge the gap between theoretical analysis and practical application.
Experimental observation – It refers to the systematic process of gathering empirical data by manipulating specific variables in a controlled environment to establish cause-and-effect relationships. It provides the physical insight and evidence necessary to formulate theories, design new systems, and validate engineering models.
Experimental parameter – It is a specific, quantifiable variable, condition, or setting which is purposefully controlled, altered, or measured during an experiment to evaluate its effect on a system. These parameters are foundational for empirical testing, system modeling, and product optimization.
Experimental plant – It is a pilot facility designed to test new materials, processes, or technologies on a smaller, scalable level. It focuses on exploring process uncertainties and human factors to refine full-scale operations.
Experimental plate – It frequently refers to a physical flat component or boundary used to study heat transfer, fluid dynamics, or structural stress. For example, a heated experimental plate is frequently used in fluid mechanics to observe thermal instability or boundary layer formations.
Experimental set-up – It refers to the specific physical configuration, testing environment, and arrangement of equipment designed to investigate a hypothesis or test a physical system. It translates a theoretical or mathematical model into actionable, empirical testing by manipulating variables and measuring outcomes.
Experimentation – It is the iterative process of testing materials, designs, and prototypes through trials to evaluate performance, validate models, and refine products before final production. It is an important, frequently iterative component of the design process, where engineers manipulate variables to gain knowledge, reduce uncertainty, and ensure safety and functional requirements are met.
Experimentation platform – It is a system which allows teams to test product changes, features, or infrastructure variations with real users. It manages randomized traffic allocation (e.g., A/B testing) and tracks performance metrics, replacing guesswork with data-driven decision-making. In software and systems engineering, an experimentation platform consists of three core components namely experiment management, experiment execution, and experiment analysis.
Experimental pressure distribution – It is the set of physical pressure values measured at different points across the surface of an object interacting with a fluid (such as in a wind tunnel). It is used to calculate forces like lift and drag, and to validate theoretical aerodynamic models.
Experimental range – It defines the minimum and maximum boundary values over which an independent variable or factor is intentionally varied during a test. It sets the operational envelope for an experiment, allowing engineers to systematically observe how a process or system responds to changing conditions.
Experimental reactors – These are non-commercial facilities utilized to test new technologies, materials, and physics regimes. Unlike production or power reactors, they serve as testing platforms to study radiation effects, validate new designs, or generate controlled neutron sources.
Experimental report – It is frequently called a laboratory report. It is a formal document which outlines an experiment. It provides precise data reporting, statistical analysis, and clear indications of uncertainties. Its main purpose is to narrate the research story, objectively present findings, and validate the reliability of the engineering design or concept.
Experimental response – It is the measurable physical or behavioural output of a system or material when subjected to specific, controlled inputs or environmental conditions. It provides real-world data used to validate computer simulations, evaluate performance limits, and characterize material properties.
Experimental results – These are the quantitative data, measurements, and observations gathered by executing a test or experiment. These are empirical evidence used to evaluate a system’s physical performance, validate theoretical models, and determine material properties. These findings are necessary for bridging the gap between abstract design and real-world application.
Experimental run – It is a single, continuous execution of a process or test under a specific set of input parameters. It involves applying deliberate values to variables to measure their impact on the output. It is the fundamental building block of the design of experiments (DoE).
Experimental session – It is a distinct, controlled period of data collection from a system, prototype, or human subject. It normally involves one or more experimental runs where independent variables are manipulated to measure their effect on dependent variables, ultimately evaluating a hypothesis or system performance.
Experimental stress – It refers to the measured force per unit area applied to a material during mechanical testing. It is a physical quantity used to determine how a structure deforms under real-world loading conditions. [It serves as the foundation for experimental stress analysis (ESA), which is the practice of evaluating stresses and strains in materials through physical tests rather than just theoretical or numerical models.
Experimental stress analysis – It is the use of physical testing and instrumentation to measure, analyze, and map the mechanical stresses and strains experienced by a material, component, or structure under real-world loading conditions. Since calculating complex stress states, which need defining multiple stress, strain, and displacement tensors, can be mathematically impossible or computationally uncertain, engineers rely on experimental stress analysis (ESA) to capture real-world data and validate theoretical models.
Experimental technique – It is a systematic method or procedure used to measure, analyze, and characterize physical phenomena. It involves manipulating specific variables to observe their effects on a system, allowing engineers to validate theoretical models, measure material properties, and determine real-world operational performance. Engineers rely on these techniques to bridge the gap between abstract mathematical models and physical reality.
Experimental trend – It refers to the observed, directional relationship between variables within experimental data. It is the graphical or statistical pattern which emerges when engineers test how changing one parameter affects another, helping to validate hypotheses and optimize system performance.
Experimental trial – It is an individual run-through of a controlled experiment where specific variables are deliberately altered to observe their impact on system performance. It provides the empirical data needed to validate theoretical models, optimize designs, and establish cause-and-effect relationships.
Experimental uncertainty – It is a quantified estimate of the range within which a true value lies. It accounts for the unavoidable deviations in physical measurements caused by equipment limitations, calibration, and environmental factors, establishing a confidence level.
Experimental value – It is a quantitative measurement or data point collected through direct observation or testing in an empirical setting. It represents the actual, real-world performance of a system or material, as opposed to a purely theoretical calculation.
Experimental velocity profile – It is the measured distribution of a fluid’s speed and direction as it flows through a confined space or across a solid surface. It is generated using physical instrumentation rather than purely theoretical fluid dynamics calculations.
Experimental work – It refers to the hands-on process of testing prototypes, materials, and systems under controlled conditions. Its main goal is to validate theoretical models, measure real-world performance, and collect empirical data to solve practical design problems.
Expert determination – It is a private, contractual dispute resolution method where an independent technical expert makes a binding or non-binding decision on technical, financial, or valuation issues. It is normally used in construction and engineering projects to quickly resolve technical disputes, such as variations, defects, or project delays, by leveraging industry expertise rather than formal legal arbitration.
Expert network – It is an intermediary business which connects organizations and institutional researchers with vetted subject-matter experts (SMEs) for specialized, on-demand industry insights. Customers use these networks to conduct due diligence, validate investment theses, or solve niche operational and market challenges. The term ‘expert network’ takes on two distinct definitions depending on whether you are looking at it from a business perspective or an engineering / computer science perspective:
Expert opinion – It is a specialized technical assessment formed by a qualified professional based on industry standards, technical analysis, and specific data investigations. It translates complex technical problems into clear, objective conclusions.
Expert system – It is a computer-based system which captures the knowledge of experts through the integration of databases and knowledge bases using search and logic deduction algorithms.
Expert training – It is a specialized, high-level learning process designed to cultivate mastery in a specific field, focusing on developing advanced technical knowledge, situational assessment, and decision-making skills. It is characterized by structured, evidence-based methods and frequently involves mentorship to achieve, maintain, or elevate expert performance.
Expert witness – It is a specialist with advanced knowledge, education, or experience in a specific field. Unlike standard eye-witnesses who testify only to what they saw or experienced, expert witnesses are permitted to provide professional opinions, analyze complex evidence, and help in understanding technical matters.
Explanatory data analysis – This analyzing method is used to determine the consequences happening to one variable when changing another one using randomized trial data sets.
Explicit dependence – It occurs when a variable, object, or system is defined or stated clearly, directly, and without ambiguity in terms of another. It isolates the dependent component so that you can directly calculate or observe how it relates to its independent inputs.
Explicit Euler method – It is also known as the forward Euler method. It is a fundamental first-order numerical procedure used to solve ordinary differential equations (ODEs) with a given initial value. It works by using the derivative at the current point to linearly approximate the function’s value at the next step.
Explicit expression – It defines a mathematical relationship clearly, stating exactly how to calculate a value. In this type of expression, the dependent variable is isolated directly on one side of an ‘equals’ sign, allowing people to find a solution by plugging in values without guessing or rearranging the equation.
Explicit feedback – It is direct, intentional input provided by a user or learner to express their precise opinions or performance. It needs conscious effort, such as clicking a ‘thumbs up’, completing a survey, or leaving a written comment, and contrasts with implicit feedback, which is passively inferred from behaviour like clicks or watch time.
Explicit formula – It is also called analytical expression. It defines a direct, closed-form relationship which calculates an unknown variable without the need for iterative guessing. One is to simply plug in the known values to get the result.
Explicit integration method – It is a numerical technique used to solve time-dependent differential equations. It determines the future state of a system based entirely on known data from the current time step. This eliminates the need to solve complex systems of simultaneous equations or perform iterative guesses.
Explicit power – It refers to a mathematical expression or dynamic process where a physical variable is solved for directly, using a closed-form formula, rather than through iterative guessing.
Explicit solver – It is a numerical method used in finite element analysis (FEA) to calculate the physical response of a system by directly evaluating future states from the current known state. It does this without the need for complex, iterative matrix inversions at every step. Since it calculates the next state step-by-step using an extrapolation, it is ideal for capturing fast, transient, and highly non-linear events.
Exploded assembly drawing – It shows exploded axonometric views. In the exploded views, the parts are positioned in the sequence of assembly, but separated from each other. Drawings of this type can be easily understood even by those with lesser experience in the reading of drawings, since in these exploded views, the parts are positioned in the sequence of assembly, but separated from each other.
Exploded views – These are typically used in assembly drawings in order to show the relationship or order of assembly of the different parts. An exploded view shows the components of an object slightly separated by distance, or suspended in surrounding space in the case of a three-dimensional exploded diagram.
Exploratory bore-holes – These are narrow, deep shafts drilled into the ground to extract core samples and gather precise sub-surface data. These bore-holes physically confirm the geological, geo-technical, and hydrological conditions of a site before the design and construction of heavy structures, foundations, or underground utilities.
Exploratory data analysis – It is the initial, critical phase of investigating datasets to summarize main characteristics, identify anomalies, and detect patterns using visualization and statistical methods. It serves as a foundational ‘detective work’ step, enabling engineers to refine data, test assumptions, and validate hypotheses before deploying predictive models.
Exploratory design – It is an iterative, open-ended phase used when a problem is undefined or when designing systems needing future technologies. It relies on hypothesis generation, feasibility analysis, and prototyping to clarify unknowns before committing to rigorous, production-level development.
Exploration – It consists on prospecting, sampling, mapping, diamond drilling and other work involved in searching for ore. It is a term embracing geophysics, geochemistry, and finally the more costly activities namely drilling into the ground for getting samples from any depth. Efficient exploration depends on increasingly sophisticated map production for planning purpose and access routes, for geological, geophysical, geochemical and structural mapping. Today detailed aerial topographic maps are available giving the explorer basic information to determine where to find areas with good potential of ore deposit.
Exploration geophysics – It is the applied branch of geophysics which employs different methods to measure the physical properties of the earth’s subsurface, in order to detect or infer the presence and position of valuable minerals, hydrocarbons, geothermal reservoirs, groundwater reservoirs, and other geological structures. Seismic, gravitational, magnetic, electrical and electromagnetic methods are frequently used.
Exploratory data analysis – It means using statistical and visualization techniques to understand a dataset’s characteristics, patterns, and relationships without preconceived notions. It’s an iterative process that helps uncover hidden insights, identify potential problems like outliers or missing data, and guide further analysis or modeling. This analyzing method is used to explore the unknown relationships and discover new connections, and define future studies or questions.
Exploratory engineering – It is the process of designing and analyzing detailed hypothetical models of systems which are not feasible with current technologies or methods, but do seem to be clearly within the bounds of what science considers to be possible. It normally results in prototypes or computer simulations which are as convincing as possible to those that know the relevant science, given the lack of experimental confirmation.
Explosibility – It is the inherent susceptibility of a material to undergo a sudden, rapid oxidation or decomposition reaction, releasing heat and gas to produce a destructive pressure wave. It is an important parameter in process safety and mechanical design for preventing catastrophic failures in industrial environments.
Explosion – It is a rapid expansion in volume of a given quantity of matter associated with an extreme outward release of energy, normally with the generation of high temperatures and release of high-pressure gases. Explosions can also be generated by a slower expansion which normally is not forceful, but is not allowed to expand, so that when whatever is containing the expansion is broken by the pressure which builds as the matter inside tries to expand, the matter expands forcefully.
Explosion characteristic – It refers to any measurable physical or chemical property which defines how a flammable substance, such as gas, vapour, or dust, ignites, burns, and generates destructive pressure. These metrics are important for designing safe industrial processes and preventing catastrophic accidents.
Explosion initiation – It refers to the process or stimulus which triggers a rapid, uncontrolled release of energy (pressure, heat, and gas). It involves delivering a specific threshold of energy to a reactive substance or system to start a self-sustaining exothermic reaction (such as combustion or detonation). The initiation phase is critical since it dictates how a system transitions from a stable state to an explosive one, and it is a main focus in both safety engineering and explosive design.
Explosion load – It is also called blast load. It is a high-intensity, transient pressure wave resulting from a rapid release of energy. Unlike standard static loads, these forces feature an extremely rapid rise time, high peak pressure, and subsequent rapid decay.
Explosion proof – It is the prevention of explosion triggered by electrical components through containment in special housings. It is a requirement for electrical devices such as solenoids and switches when exposed to a potentially explosive environment.
Explosion protection – It is used to protect all sorts of buildings and civil engineering infrastructure against internal and external explosions or deflagrations.
Explosion risk – It is the mathematical product of the probability an explosion occurs and the severity of its consequences. It is the quantitative or qualitative assessment of how combustible materials, ignition sources, and environmental factors interact to create hazards. Engineers evaluate and manage this risk through structured processes to ensure industrial safety and compliance.
Explosion welding – It is a solid-state welding process which produces coalescence by a controlled detonation, which causes the parts to move together at high velocity. The resulting bond zone has a characteristic wavy appearance.
Explosive bonding – It is also called explosive welding. It is a solid-state joining process which uses controlled explosive energy to force two or more metals together at high velocities. The resulting extreme pressure creates a high-strength, permanent metallurgical bond without melting the base materials, making it ideal for joining dissimilar metals.
Explosive compacting – It is the compacting of a powder at a very rapid rate by the use of explosives in a closed die.
Explosive decompression – It is also referred as anti-explosive decompression (AED). It is the phenomenon occurring in rubber seals after exposure to high-pressure gas. This gas permeates into the elastomer through flaw sites present in all moulded rubber products. During an equilibrium shift (rapidly lowered pressure), the gas expands within the seal causing internal ruptures in high shear modulus (hard) materials and surface blisters in low shear modulus (soft) materials.
Explosive energy – It is the rapid, exothermic conversion of chemical or nuclear energy into immense physical force, heat, and highly pressurized gas. It is characterized not by exceptionally high total energy density, but by an ultra-fast release rate which creates a destructive or shaping shock wave.
Explosive evaporation – It is the extremely rapid vapourization of a liquid which generates high local vapour pressures and potentially destructive shock-waves. It occurs when a highly superheated liquid spontaneously flashes into gas or when extreme heat transfer rapidly converts a thin liquid layer into vapour.
Explosive forming – It is the shaping of metal parts in which the forming pressure is generated by an explosive charge which takes the place of the punch in conventional forming. It is a process in which a charge generates a shock wave which deforms a sheet material against a die, with the charge either placed at a distance or directly on the sheet to achieve the desired pressure and deformation.
Explosiveness – It is the capacity of a substance or system to rapidly release potential energy, generating high-pressure gases, heat, and shockwaves in an extremely brief period. It is dictated by the speed of decomposition or combustion and the material’s ability to trigger a violent, expanding reaction. The concept is evaluated through several core areas and technical parameters.
Explosive process – It is a highly unsteady, rapid release of energy which generates extreme heat, high-pressure gases, and shock-waves. It relies on rapid exothermic chemical reactions or pressurized volume expansions to perform destructive, propellant, or material-shaping work.
Explosive-type wetting – It refers to the extremely rapid, violent spreading of a liquid metal over a solid metallic substrate, frequently accompanied by intense chemical reactions, surface cleaning, or metallurgical interaction. This phenomenon is characteristic of the extreme conditions found in explosive welding (EXW) and high-energy collision, where high pressures and temperatures facilitate wetting which is not observed under conventional conditions.
Explosive welding – It is a solid-state welding process which uses controlled chemical explosions to accelerate one metal plate (flyer) into another (base) at high velocity, creating a high-strength metallurgical bond without melting the bulk metals. It is mainly used to clad large surfaces, such as joining dissimilar metals.
Explosive well stimulation – It is also known as well shooting. It is a technique which uses controlled, high-energy chemical detonations inside a wellbore to fracture surrounding reservoir rock. The main goal is to permanently increase formation permeability, allowing trapped oil, gas, or water to flow more easily into the well.
Exponent bit – It refers to the specific bits in a computer’s floating-point number representation dedicated to storing the exponent. It determines the range of values the number can hold, while the mantissa (or fraction) dictates the precision.
Exponential approximation – It refers to a method of estimating the packet error probability (PER) in coded transmission systems using a simplified exponential function characterized by two parameters, which is derived from simulation results to minimize relative quadratic error.
Exponential auto-correlation – It describes how a signal’s similarity to itself drops off over time or distance as per a mathematical exponential decay. It models the behaviour of random, noisy processes (stochastic processes) where past events dictate the future, but that memory gradually fades.
Exponential decay – It is a process where a quantity decreases at a rate directly proportional to its current value. The speed of the decrease slows down as the quantity becomes smaller, mathematically modeled using exponential decay. Exponential decay phenomenon is prevalent in different fields, including nuclear physics, where it describes the decay of natural radioactive nuclei.
Exponential decay model – It describes a quantity which decreases over time at a rate proportional to its current value. It is widely used in several disciplines. physics (radioactive decay), chemistry, and finance (asset depreciation).
Exponential decline – It refers to a production rate which decreases at a constant rate over time, characterized by a straight line on a semi-log plot, where the decline rate remains constant and is defined by the initial production rate and the decline rate.
Exponential distribution – It is a continuous probability distribution which models the time or distance between independent events in a Poisson process. It is mainly used to calculate the time elapsed before an occurrence, such as component failure. It is typically used to model life cycles or decay of materials or events.
Exponential drop – It refers to a process where a quantity decreases at a rate proportional to its current value. This means the drop is very rapid initially and gradually slows down as the value approaches zero over time.
Exponential factor – It typically refers to a mathematical term of the form (‘e’ to the power ‘at’, where ‘e’ is Euler’s number, ‘a’ is a constant, and ‘t’ is time). It defines processes where a quantity’s rate of change is proportional to its current value, such as radio-active decay or the charging of a capacitor.
Exponential Fourier series – It is a tool used to break down complex periodic signals into a sum of simple, harmonically related complex exponentials. It acts as a bridge between the time-domain and frequency-domain, making the analysis of electronic circuits and communication systems much more mathematically efficient.
Exponential function – It is a mathematical function denoted by 𝑓(𝑥)=exp(𝑥) f(x) = exp(x) or𝑒𝑥 ‘e’ to the power ‘x’, (where the argument ‘x’ is written as an exponent). Unless otherwise specified, the term generally refers to the positive-valued function of a real variable, although it can be extended to the complex numbers or generalized to other mathematical objects like matrices.
Exponential growth – It is a process where the rate of change of a quantity is directly proportional to its current value. This creates a rapid, accelerating pattern (frequently visualized as a J-curve) where growth compounds continuously over time. It contrasts sharply with linear growth, which simply adds a constant quantity over time. While powerful, true exponential growth is normally limited in the physical world by constraints like resource depletion, carrying capacity, or system limits.
Exponential notation – It is a standardized way to write and calculate extremely large or small numbers using powers of 10. It expresses numbers in the format ‘a’ times 10 to the power ‘n’, where ‘a’ is the coefficient and ‘n’ is the integer exponent.
Exponential reliability function – It is a mathematical model in reliability engineering which calculates the probability a component or system operates without failure over a specific period of time, assuming a constant failure rate.
Exponential smoothing – It is a time series regression in which recent observations are given more weight by way of exponentially decaying regression coefficients.
Exponential softening – It is a constitutive material model describing how a material gradually loses its load-bearing capacity and stiffness after reaching its peak stress. It typically defines the post-peak behavior of brittle materials like concrete, rock, or composites as they crack or yield.
Exponential stability – It defines a system where an equilibrium point is approached at a rate specified by an exponential decay function. It ensures which system trajectories converge to the equilibrium state faster than or equal to a decreasing exponential function, guaranteeing both stability and a guaranteed speed of response.
Exponential term – It refers to any mathematical expression where an independent variable appears in the exponent position. These terms represent processes where the rate of change is proportional to the current value, perfectly describing exponential growth (compounding, rapid increases) or exponential decay (diminishing, discharging). It refers to a mathematical component in generalized multi-compartment models that represents distinct phases in the plasma concentration versus time curve, including absorption, distribution, and elimination rates, characterized by specific rate constants.
Exposed node – It refers to a scenario in a communication network where a transmitter can send signals to its receiver without interference, even though it is unable to transmit simultaneously because of a protocol which restricts transmission when the channel is perceived as occupied. This situation can lead to underutilization of the communication channel.
Exposure – It refers to the contact between a target (person, system, or material) and a specific agent (pollutant, hazard, or environmental condition). It defines the extent to which a system is subjected to external forces, such as structural loads, hazardous materials, or, in education, real-world industry practices. In case of radiography, it is the exposure of an organism to a source of radiation characterized by the dose received. External exposure is the exposure from a radiation source located outside the organism, while the internal exposure is the exposure from a radiation source located inside the organism.
Exposure control – It refers to the methods used to protect personnel from hazardous substances or physical agents. Engineering controls specifically involve physical modifications to equipment, processes, or work-stations to eliminate or reduce hazards at their source or along their transmission path.
Exposure dose – It is the specific amount of an agent (such as a chemical contaminant, radiation, or pollutant) which crosses an individual’s physical boundary (like the lungs, or skin). It is the actual quantity taken into the body, as opposed to the concentration present in the environment.
Exposure effects – These refer to the health outcomes which result from human exposure to toxic agents, where the relationship between the source of exposure and the resultant health effects is established through epidemiologic studies and clinical investigation. These effects can be influenced by factors such as the route and magnitude of exposure, which are critical for understanding and managing health risks associated with environmental and occupational toxicants.
Exposure estimation – It is the process of quantifying the magnitude, frequency, and duration of contact between individuals or populations and environmental or occupational hazards (e.g., chemicals, radiation, or noise). It is a core component of risk assessment used to design safe systems and protective equipment.
Exposure factor – It is a variable used to calculate external forces or risks. Depending on the discipline, it evaluates how much a building is subjected to wind and weather, the electrical loads needed for imaging, or the physical risk to assets.
Exposure geometry – In radiography and nondestructive testing (NDT), it is the spatial arrangement and distance relationship between a radiation source, the test sample, and the detector or film. Optimizing these geometric factors ensures maximum image clarity and minimizes penumbra or blurriness.
Exposure index – It is the relative transmittance or optical density of a selected spectral line, this value serving to indicate the degree of blackening of the photographic emulsion.
Exposure information – It typically refers to data defining the contact, magnitude, and duration of a population or individual with a hazardous physical, chemical, or biological agent. It is a core component of risk management, guiding safety protocols, hazard controls, and protective equipment design.
Exposure level – It defines the specific magnitude or concentration of a physical or chemical agent (such as noise, toxic dust, or radiation) an individual or structure is subjected to over a stated period. It is mainly used to assess risks and ensure compliance with established health, safety, and design thresholds.
Exposure potential – It defines the likelihood, probability, and magnitude of individuals or populations coming into contact with a physical, chemical, or radiological hazard. It is a foundational metric used to evaluate risks, establish exposure levels, and design safe control systems.
Exposure profiles – These are estimates of the magnitude and spatial and temporal patterns of exposure to chemical stressors, developed using data from exposure analyses to inform risk characterization. These profiles typically incorporate measures such as the quantity of chemical and its distribution across different scenarios.
Expression yields – These refer to the quantity of liquid extracted from a solid matrix during expression processes, influenced by factors such as the compressibility of the solid, the viscosity of the liquid, and the pretreatment of the material. The yield can vary based on the pressure applied and the duration of the expression, with higher pressure frequently leading to different quality grades of the expressed liquid.
Expressiveness – It is also called expressive power. It is the breadth of ideas, relationships, or algorithms which can be concisely and clearly represented within a specific language, model, or system. A highly expressive tool allows a user to do more with fewer lines of code or complex configurations.
Expulsion force – It refers to the mechanical or physical force used to eject, propel, or separate material from a designated area.
Ex-situ composites – These are metal matrix composites (MMCs) produced by adding pre-synthesized reinforcement particles (such as ceramic particles, whiskers, or fibres) into a molten or powdered metal matrix during fabrication. Unlike in-situ composites, the reinforcement is manufactured separately and does not form through chemical reactions during processing, frequently resulting in larger particle sizes.
Extend – It means adding fillers or low-cost materials in an economy-producing endeavour. It is the adding of inert materials for improving void-filling characteristics and reduce crazing.
Extendable transport module – It is a specialized roller or wheel conveyor equipped with the flexibility to be extended or retracted within defined limits, catering to evolving operational demands. Standard extensions come in lengths of 5 meters, 10 meters and 15 meters, necessitating periodic assessments and adjustments.
Extended analysis – It typically refers to advanced numerical and simulation techniques (such as the extended finite element method, or XFEM) used to model complex physical phenomena, like cracks or phase changes, without needing costly, time-consuming mesh updates.
Extended automation – It represents an evolution of traditional control systems (distributed control system / programmable logic controller) towards an open, modular, and cyber-secure ecosystem which integrates advanced digital technology with core operational technology (OT) without replacing the underlying, reliable control infrastructure. Engineering for extended automation involves bridging the gap between existing ‘rip-and-replace’ paradigms and the adoption of modern technologies such as artificial intelligence (AI), machine learning (ML), and Industrial internet of things (IIoT).
Extended blow-down valve – It is used on buried valves where the drain plug is inaccessible. Instead, a line is piped above ground, terminating in a small valve. Line pressure is used to blow-out condensates and other material which settles in the bottom of the body cavity.
Extended chain polyethylene (ECPE) fibre – It is an ultra-strong, light-weight, and high-modulus synthetic fibre derived from ultra-high molecular weight poly-ethylene. Engineered to maximize tensile strength and stiffness, it is predominantly used in several demanding applications.
Extended contract – It refers to a formal agreement which extends the duration of an existing contract beyond its original end date, without needing to create a completely new agreement. It allows the parties to push the date of termination further to complete ongoing obligations, frequently used when project scope changes, unforeseen delays occur, or a project nears completion.
Extended cyclic prefix – It is a longer guard interval used in ‘orthogonal frequency division multiplexing’ (OFDM) systems. It copies the end of an orthogonal frequency division multiplexing symbol and pastes it at the beginning. By doing so, it serves as a temporal buffer to prevent delayed multi-path signals from corrupting subsequent data streams.
Extended defect – It is an imperfection which affects a large region of a crystal lattice, disrupting its long-range, orderly structure. Unlike localized point defects, these encompass multiple atoms or molecules and frequently dictate the mechanical, electrical, and optical properties of the material.
Extended dislocation – It is a crystallographic defect where a single, larger dislocation splits into two or more smaller ‘partial’ dislocations. When these partial dislocations separate, they leave behind a two-dimensional ribbon of an imperfect crystal structure called a stacking fault.
Extended heat transfer surface – It is normally called a fin. It is a solid structure attached to a main surface to increase the total heat transfer area. It facilitates concurrent convective and conductive heat transfer, improving thermal performance relative to the base object.
Extended idler spacing – It refers to the practice of increasing the distance between conveyor belt idler sets beyond standard recommendations (which frequently range from 0.8 meters to 2.5 meters). This technique is utilized, particularly in long-distance or high-capacity conveyors, to reduce the total number of idlers, aiming to minimize capital investment, lower operational costs, and reduce energy consumption.
Extended Kalman filter – It is a recursive mathematical algorithm used to estimate the unknown state of a dynamic system from a series of noisy measurements. Unlike the standard Kalman filter, which only handles linear systems, the extended Kalman filter (EKF) can accommodate non-linear systems by continuously linearizing them around the current estimate.
Extended operation – It typically refers to a custom command or a set of advanced derived operators which go beyond a system’s standard set of basic functions. Depending on the field, it has highly specific technical meanings, most notably in databases, cryptography, aviation, and corporate business operations.
Extended plate – It is also called end plate. It is a specialized metal plate used in structural engineering to connect beams to columns, adding rigidity to the joint. The plate is welded to the beam’s end in a workshop and bolted on-site to the column flange, and extends past the beam flange to provide extra leverage against bending.
Extended range electric vehicle – It is an electric vehicle which relies mainly on an electric motor to turn the wheels, but features an onboard internal combustion engine (or fuel cell) which acts exclusively as a generator to recharge the battery when depleted. Since the combustion engine never mechanically connects to the drive axles, extended range electric vehicle (EREVs) operate fundamentally as pure electric vehicles but completely eliminate ‘range anxiety’.
Extended state observer – It is a control theory algorithm which estimates both the internal states of a system and its ‘total disturbance’ (unmodelled dynamics, friction, and external forces) in real-time. It achieves this by treating these unknown disturbances as an additional, fictitious state within the system.
Extended temperature range – It refers to the operating or storage limits of a device or component which exceed standard (commercial) specifications. While standard commercial devices typically operate from 0 deg C to 60 deg C, extended-grade components are designed to withstand considerably harsher, hotter, or colder environments.
Extended thermodynamics – It is an advanced framework of non-equilibrium thermodynamics which expands traditional theories by treating macroscopic fluxes (such as heat and momentum) as independent variables. It resolves physical paradoxes and effectively models rapid, small-scale processes.
Extended X-ray absorption fine structure – It is the weak oscillatory structure extending for several hundred electron volts away from an absorption edge. The oscillations occur since the electro-magnetic wave produced by the ionization of the absorbing atom for some energy ‘E’ has a wavelength Lambda = 1.225/(E-Ek) to the power 1/2 nanometer, where ‘Ek’ is the energy of the absorption edge. For example, a loss of 100 eV (electron volt) above an edge corresponds to a wavelength of 0.12 nano-meter, which is of the order of atomic spacing. Consequently, the wave can be diffracted from neighboring atoms and return to interfere with the outgoing wave. An analysis of extended X-ray absorption fine structure (EXAFS) data reveals important information about atomic arrangements and bonding. Either synchrotron x-radiation or the electron beam in the analytical transmission electron microscope can be used as the excitation source.
Extended X-ray absorption fine structure spectroscopy – It is a technique that uses destructive and constructive interference effects to provide detailed information about the coordination number and distances to neighboring atoms, particularly useful in analyzing the local atomic environment in different materials.
Extender – It is a specialized device, chemical, or software component designed to extend the physical reach, structural capability, or functional distance of an existing system, signal, or material. Extenders are low-cost materials which are used to dilute or extend high-cost resins without extensive lessening of properties.
Extensibility – It is the ability of a material to extend or elongate upon application of sufficient force, expressed as percent of the original length. It is a design principle where a system, framework, or material is built to easily accommodate future growth, feature improvements, or physical modifications without needing major overhauls. It emphasizes flexibility, adaptability, and minimal disruption to the original structure.
Extensible hyper-text mark-up language – It is part of the family of XML (extensible mark-up language) mark-up languages which mirrors or extends versions of the widely used hyper-text mark-up language (HTML), the language in which web pages are formulated.
Extensible mark-up language – It is a flexible, text-based language designed to store and transport structured data by allowing users to define their own custom tags, making it both human- and machine-readable. Extensible mark-up language (XML) is a W3C (world wide web consortium) recommendation widely used for data exchange, configuration files, and web services.
Extension – It is the act of lengthening, stretching out, or enlarging the scope, time, or size of something. It refers to an addition which increases the capacity of an existing structure or system, such as a building addition, an extra telephone line, or a deadline prolongation.
Extensional-bending coupling – It is a property of certain classes of laminates which show bending curvatures when subjected to extensional loading.
Extensional flow – It is also called elongational flow. It is a fluid deformation where a velocity gradient occurs in the same direction as the flow itself. Unlike shear flow (where fluid layers slide past each other), extensional flow stretches a fluid element in one direction and compresses it in others.
Extensional-shear coupling – It is a property of certain classes of laminates which show shear strains when subjected to extensional loading.
Extensional stiffness – It is also called axial stiffness. It measures an element’s ability to resist stretching or compressing along its length when subjected to an applied load. It depends on the material’s elastic properties, the cross-sectional area, and the length of the structural member.
Extension bonnet – It is a bonnet with higher dimension between the packing box and bonnet flange for direction hot or cold service.
Extension direction – It refers to the orientation along which the dominant eigenvector of the tensor order parameter ellipsoid aligns, influencing the structural state of materials under extensional flow.
Extension headers – These are additional segments appended to the basic IPv6 (internet protocol version 6) header which provide extra information to the IP (internet protocol) layer, including functionalities such as fragmentation, routing, destination options, and hop-by-hop options. These headers allow networks to handle specialized tasks, like fragmentation, routing, and security, without cluttering the base packet header.
Extension layer – It is a modular architectural component built on top of a core system. It allows software, networks, or physical models to scale and add new features without altering or disrupting the original, foundational code-base.
Extension lead – It is also called extension cord. It is a flexible length of electrical power cable featuring a plug on one end and one or more sockets on the other. It temporarily extends the reach of a power supply to appliances which are beyond the physical reach of their built-in cords. These devices are designed to meet rigorous safety, mechanical, and thermal specifications to prevent circuit overloading and hazards.
Extension line – In engineering drawing, it is a thin, solid line which extends from an object’s boundary to define the specific area being measured, connected to a dimension line to show precise measurements without crowding the drawing. Extension lines begin with a 1 millimeter to 2 millimeters gap from the object and extend slightly beyond the dimension line.
Extension line origin – It is the starting point from which extension lines are drawn in a dimensioning process, allowing for the specification of a dimension’s length and position in technical drawings.
Extension meter – It is normally known as an extensometer. It is a high-precision instrument used to measure minute changes in the length, deformation, or strain of a material or structure under applied mechanical or physical stress.
Extension ratio – It is a measure of how much a material stretches under uniaxial tension. It is defined as the ratio of the stretched, current length (l) to the material’s original, unstrained length (Io).
Extension spring – It is a tightly coiled helical spring designed to absorb and store energy while resisting a pulling force. When mechanisms pull apart, the spring extends, creating a reaction force which draws the components back together to their original position.
Extension stem – It is also called extensions. It is the equipment applied to the buried valves to provide above grade accessibility to operating gear, blowdown, and seat sealant systems.
Extension, surface – Surface extension refers to the adjustment of damper border dimensions relative to the air gap height in a simplified model that extends the applicability of certain flow models, with the extension depending on the Knudsen number (Kn). The extension is calculated using a specific formula that accounts for the continuum and rarefied gas flows.
Extension-under-load (EUL) yield strength – It is a method for determining the yield point of a material which does not have a sharp, distinct yield point, such as stainless steel or aluminum. It is defined as the stress applied when the total strain (elastic + plastic) reaches a specific, predefined percentage, such as 0.5 % or 0.6 %.
Extension wire – It is a specially designed, flexible electrical cable used to extend a power or signal circuit across a distance. It carries electrical current, data, or thermal readings without altering the signal, though its length, thickness, and material is to be carefully engineered to prevent voltage drop and overheating.
Extensive property – It is a physical quantity whose value is proportional to the size of the system it describes or to the quantity of matter in the system. Examples include mass, volume, enthalpy, and entropy.
Extensometer – It is an instrument for measuring changes in length over a given gauge length caused by application or removal of a force. It is normally used in tension testing. It is a mechanical or optical device for measuring linear strain due to mechanical stress.
Extent of reaction – It is a fundamental quantitative measure which describes how far a chemical reaction has progressed, tracking the cumulative moles of a substance consumed or formed based on reaction stoichiometry.
Exterior application – It refers to the use of materials, protective finishes, or hardware exposed directly to environmental elements. It needs careful design considerations for weather resistance, durability, moisture control, and UV (ultra-violet) protection to prevent structural degradation and corrosion.
Exterior column – It is a vertical structural member positioned on the perimeter of a building. It transfers gravity (compressive) loads from roofs and floors to the foundation while uniquely resisting lateral forces like wind and earthquakes. Unlike interior columns, which bear mainly vertical dead and live loads, exterior columns operate under complex combined stresses. Since they rest on the outside of the structure, they are subject to specific engineering dynamics, materials, and challenges.
Exterior hoods – These are exhaust systems which are typically easy to install and cost-effective, used when the exhaust source is close to the hood, and the demands on the exhaust and hazard of contaminants are moderate. These include different types such as basic openings, rim exhausts, low-volume high-velocity hoods, receptor hoods, and downdraft ventilation tables.
Exterior noise – It normally refers to the airborne sound radiated by a piece of equipment, vehicle, or facility into the surrounding environment. It is defined by its source, how it propagates, and the regulations governing permissible sound levels.
External – It refers to any force, signal, or component originating outside the boundaries of a specific system. The term defines how a designed system interacts with its surrounding environment.
External armour layer – It is a protective coating applied to equipment components exposed to external wear, needing periodic scrutiny and timely replacement to sustain optimal performance.
External calcium – It refers to calcium ions supplied from external substances (such as calcium chloride, calcium nitrate, or calcium lactate). It is mainly used in construction and materials engineering to drive biological or chemical precipitation reactions, such as inducing crack-healing in concrete.
External calibration – It is the process of verifying and adjusting a measuring instrument by comparing its readings to a known, certified reference standard. It ensures that the device’s measurements are highly accurate and directly traceable to national or international benchmarks.
External capacitor – It is a discrete capacitor connected outside of an integrated circuit (IC) or module. It is used to provide bulk energy storage, stabilize power supplies, or fine-tune frequencies which cannot be efficiently built into the silicon chip itself. Like all capacitors, an external unit works by storing electrical energy in an electrostatic field. It consists of two conductive metal plates separated by an insulating material called a dielectric.
External cavity – It refers to a configuration where a resonator or optical path is extended outside of a main gain medium (typically a laser diode) using external optical elements. It is mainly used to suppress unwanted modes, stabilize the system, and provide highly precise tuning of the emission frequency.
External chills – These are high-density, high-thermal-conductivity materials, typically steel, iron, or graphite, placed inside a sand mould cavity, directly touching the casting surface to accelerate local cooling. By rapidly removing heat from thicker sections, they create steep temperature gradients, enabling directional solidification to reduce shrink defects and improve structural soundness.
External circuit – It consists of wires, connectors, measuring devices, and current sources etc., which are used to bring about or measure the desired electrical conditions within the test cell. It is this portion of the cell through which electrons travel.
External coating – It is the coating applied to protect valves against different environments i.e., sea air, salt water, earth buried, and normal air exposure.
External combustion heat engine – It is a system where the fuel burns outside the engine, and the resulting thermal energy is transferred to a separate internal working fluid (like water, air, or helium) through a heat exchanger. This heated fluid expands to generate mechanical work.
External connection – It is a bridge allowing data to flow between a local system (or network) and the outside world. In technology, it refers to external peripheral hardware like USB (universal serial bus) devices, network paths between different systems, or software API (application programming interface) integrations.
External convection – It is the transfer of heat between a solid surface and an unbounded fluid flowing over it (e.g., wind blowing over a flat plate, a pipe, or a car body). Unlike internal convection, which is constrained inside a pipe or channel, the fluid here is free to expand.
External coordinate – It refers to a point, vector, or measurement defined outside the immediate local frame of a specific component, body, or system. These coordinates are used to describe how that object interacts with its environment, moves within a, or connects to, a broader, fixed reference frame (like ‘world’ or ‘global’ space).
External corrosion – It is the gradual degradation and destruction of a material’s exterior surface (typically metals) caused by electro-chemical or chemical reactions with its surrounding environment. Common examples include atmospheric rusting, soil-based degradation of underground pipelines, and pitting.
External damping – It refers to the reduction of an oscillating system’s vibration or movement because of the energy loss caused by external environmental factors, such as fluid resistance, air drag, or boundary friction. It causes a system’s amplitude to decay over time.
External diameter – It is also called outer diameter (OD). It is the straight-line distance spanning the entire width of a circular, cylindrical, or spherical object, measured directly from one outer edge to the opposite outer edge through the centre.
External disturbance – It is any unwanted outside force, signal, or environmental influence that negatively impacts the stability and performance of a system. These phenomena originate from outside a specific environment and force the system to deviate from its intended or desired state.
External electric field – It is an electric field applied to a system from an outside source. It acts upon the system’s internal charges without being generated by or altered by the system itself. It is a vector quantity measured in volts per meter.
External electro-optic modulator – It is a device which alters the properties of a light beam (such as its phase, amplitude, frequency, or polarization) by applying an external voltage. It is placed ‘externally’ after a continuous-wave laser, allowing data to be encoded into light without causing undesirable frequency chirping.
External energy – It is the sum of a system’s macroscopic kinetic energy (because of its motion as a whole) and potential energy (because of an external force field, like gravity). Unlike internal energy, it describes the system’s overall state relative to its environment.
External exergy loss – It is the transfer of potentially usable work capacity (exergy) across the boundaries of a system to its surroundings, where it is lost and no longer utilized. Unlike exergy destruction (which is the internal loss of work potential because of the irreversibilities like friction or mixing), external loss involves exergy actually leaving the system.
External flow – It refers to the flow of an unbounded fluid around a completely submerged solid object. The defining characteristic is that the boundary layers develop freely without constraints from adjacent surfaces, unlike internal flows where fluid is confined.
External flush – It refers to the use of an independent fluid source, from a separate system or console, to clean, lubricate, or cool critical machinery components like mechanical seals. It is mainly used when the main fluid contains abrasive solids, is highly corrosive, or operates at extreme temperatures.
External gear – It is a mechanical component with teeth cut into the outer surface of a cylinder or cone. When two external gears mesh, they transmit torque and rotate in opposite directions. They are a fundamental machine element widely used in power transmission and hydraulic systems.
External indicator – It refers to a testing reagent which does not participate in the main reaction. Instead, it is used to detect an endpoint (such as a colour change) by testing small drops of the mixture externally, avoiding interference with the main batch. External indicators also refer to metrics used to evaluate the performance of clustering algorithms by comparing the clustering results against known labels in a dataset. These indicators include measures such as purity, mutual information (MI), adjusted mutual information (AMI), Rand index (RI), and F-measure, which assess the degree of alignment between clustering and actual classifications.
External information source – It refers to any data, record, or documentation generated outside of a facility’s internal operations or system boundaries. These sources provide important, objective data needed for comprehensive planning, hazard assessments, system analysis, and technological innovation.
External irreversibility – It is the degradation of available energy which occurs outside the system’s boundaries, specifically in the surroundings. It is mainly caused by processes operating across finite gradients, such as transferring heat across a temperature difference or encountering friction outside the working fluid.
External light source – It typically refers to a primary lighting device, illumination system, or optical power supply which is physically separated from the main device, sensor, or reactor it is supporting.
Externally applied loads – These refer to loads acting on a structure which are applied at joints or other locations, and can include point loads and distributed loads. These loads are considered in the analysis of internal forces within the structure.
Externally applied stress – It refers to the mechanical forces exerted on a material by its surrounding environment. These forces are quantified as the load applied per unit of cross-sectional area. It is the main catalyst which causes a material to deform or develop internal resistive forces.
Externally pressurized seal – it is a seal which operates on a thin film at the interface with the mating surface. The film is formed by high-pressure fluid which is brought to the interface at some mid-dam location and that is at a pressure equal to, or higher than, the up-stream seal pressure.
External magnetic field – It is a magnetic field whose source originates entirely outside the object, system, or material being analyzed. It is not influenced by the object’s internal magnetic properties and is typically denoted as ‘H’.
External mass transfer – It describes the movement of chemical species from the bulk fluid to a boundary surface (such as a solid catalyst or liquid-gas interface). It is a fundamental concept in transport phenomena and is frequently the ‘rate-limiting step’ when transport is slower than the actual chemical reaction.
External memory – It is also known as secondary memory or auxiliary storage. It refers to non-volatile storage devices which are separate from a system’s primary memory (random-access memory, RAM). It retains data persistently even when powered off and is mainly designed to hold massive data-sets, operating systems, and programmes.
External modulation – It is a high-speed telecommunications technique where a laser operates at a constant, uninterrupted wave, and an external optical device (rather than the laser itself) encodes the data. This method produces cleaner signals, eliminates laser ‘chirping’, and enables data rates exceeding 10 gigabits per second (Gbps). In optical engineering, external modulation (frequently contrasted with direct modulation) solves significant limitations found in high-band-width broad-band networks.
External modulator – It is an optical device placed after a continuous-wave laser which encodes electrical data onto a light beam by manipulating its amplitude, phase, or polarization. By separating light generation from data encoding, it prevents laser instability and enables high-speed, long-distance optical communications.
External network – It is a network, such as the internet or a partner WAN (wide area network), situated outside an organization’s internal, secure boundary. Engineered to facilitate data exchange, it operates outside the security controls of the internal network, typically needing firewalls, NAT (network address translation) devices, or proxies to manage traffic securely.
External power input – It refers to the delivery of electrical or mechanical energy from an outside source (such as the electrical grid, a generator, or a battery) to a device or system to make it perform work. It represents the total energy consumed by the system.
External power source – It is also called external power supply. It is an independent device or circuit which converts raw, high-voltage mains electricity into stable, lower-voltage current. Housed in its own enclosure separate from the equipment it powers, it connects through a cord and provides regulated power to consumer or industrial electronics.
External pressure – It is the force exerted on the outer surface of a structure or system by its surrounding environment, such as atmospheric air, water, or process fluids. It occurs when the pressure outside an object is higher than the pressure inside, creating compressive stresses which can cause the material to collapse or buckle.
External pressure gradient – It refers to the spatial rate of change of pressure along the external surface of an object in a fluid flow. It dictates whether the fluid flow accelerates or decelerates, directly influencing boundary layer development and the likelihood of flow separation.
External processor – It is a dedicated hardware module, auxiliary device, or microservice filter that operates outside the main system to perform specialized tasks, reducing the work-load on the main central processing unit (CPU).
External programmer – It is a specialized piece of hardware or external device used to transfer code (like firmware or machine code) into a microcontroller, memory chip, or FPGA (field programmable gate array).
External quantum efficiency – It is the ratio of the number of charge carriers (electrons) collected by a solar cell to the number of photons incident on the device from an external source. It is an important) wavelength-dependent measurement of how efficiently a device converts light into electricity, encompassing both optical losses (reflection) and electrical losses (recombination).
External radiation – It refers to the electro-magnetic energy emitted, absorbed, or reflected by surfaces interacting with their external surroundings. In safety engineering, it refers to a worker’s exposure to radiation sources located outside of their physical body (e.g., from X-ray machines or radioactive materials).
External radiation dose – It is a measure of the energy imparted to a physical material from a radiation source located outside the body. It is categorized into absorbed dose, equivalent dose, and effective dose, and is calculated based on radiation field strength and exposure time.
External resistance – It refers to the total electrical resistance of all components located outside the power source (such as wires, resistors, and appliances). It dictates how much current is drawn from the source and determines the useful power delivered to the load.
External resistor – It refers to any discrete, stand-alone resistor connected outside of a main component, integrated circuit (IC), or power source. It is used to modify, protect, or interface with a circuit, such as providing bias, limiting current, or acting as a pull-up / pull-down.
External resonance – It is a phenomenon where an external, periodic force or vibration causes a system to oscillate with considerably higher amplitude since the external frequency matches the system’s natural frequency. It acts as a maximum energy transfer mechanism, amplifying vibrations, sound, or electric current.
External screw – It is defined as a type of screw which features a helical thread wound around a cylinder, which is used in conjunction with corresponding internal threads in nuts or other components to create a fastening mechanism.
External sheath – It is the outermost protective covering of a cable or composite structure. It acts as the main barrier shielding internal components (like conductors or optical fibres) from mechanical stress, moisture, chemicals, and environmental hazards.
External shielding overlay – It is a protective covering strategically applied to shield equipment components from external wear, prompting systematic inspections and timely replacement whenever necessary.
External signal – It is an input, stimulus, or data originating outside a system or circuit. These electro-magnetic, digital, or physical variations trigger, control, or inform the system’s operation, needing conditioning or translation by sensors.
External stimulation – It is the deliberate application of an outside force, energy, or signal to a system, such as electronic components, to predictably control, measure, or alter its behaviour and function.
External stream – It refers to the motion of a fluid around a solid body that is completely immersed and unbounded. Unlike internal flows (like fluids inside a pipe), the boundary layers in external streams develop freely without constraints from adjacent solid surfaces.
External stress – It refers to the external mechanical forces (like tension, compression, or shear) exerted on a material from the outside. Since these forces try to deform the material, the object naturally generates an internal resisting force. This internal resistance per unit area is technically what is measured as stress.
External structure – it normally has two distinct definitions. It can refer to exterior structural elements (like facades or columns) supporting a building, or to an external structural frame applied to an existing building for seismic retrofitting.
External test equipment – It refers to standalone diagnostic, measurement, or stimulus devices needed to troubleshoot and maintain a system when its internal or built-in test capabilities are insufficient. It is important for assessing reliability, verifying performance, and diagnosing complex malfunctions across different engineering domains.
External thread – It frequently called a male thread. It is a continuous helical ridge or groove formed on the outer surface of a cylinder or cone. Mainly utilized on screws, bolts, and studs, it mates with a complementary internal thread to join components or transmit mechanical motion.
External tooling for direct external and internal shape production – It involves CAD (computer-aided design) / CAM (computer-aided manufacturing) software and specialized hardware used to directly program, design, and manufacture complex internal and external geometries without intermediate models. Key technologies include CNC (computer numerical control) turning with customized form tools, 3D printing (additive manufacturing) for direct tool fabrication, and computer-aided design based design for internal profiled cutting tools.
External tooth gear – It is the most common type of spur gear. It has teeth cut on the outside perimeter of mating cylindrical wheels, with the larger wheel called the gear and the smaller wheel the pinion. The simplest arrangement of spur gears is a single pair of gears called a single reduction stage, where output rotation is in a direction opposite that of the input which means that one is clockwise while the other is anti-clockwise. Higher net reduction is produced with multiple stages in which the driven gear is rigidly connected to a third gear. This third gear then drives a mating fourth gear that serves as output for the second stage. In this manner, several output speeds on different shafts can be produced from a single input rotation.
External triggering – It is the use of a signal originating outside a measurement or control system to synchronize the device’s data capture or process operations. It allows equipment like oscilloscopes or micro-controllers to align their measurements with specific external events rather than relying on internal timing.
External velocity – It typically refers to the speed and direction of a fluid (like air or water) flowing outside or around a solid object, such as an airfoil, building, or pipe. It is the freestream flow outside the boundary layer where surface friction and viscous effects are negligible.
External velocity distribution – It defines how the speed and direction of a fluid change as it flows around a solid, immersed object. It is mainly driven by the object’s geometry, the fluid’s free-stream conditions, and the angle of attack.
External virtual work – It is the hypothetical work done by actual external forces and loads as they act through an imaginary, infinitesimally small ‘virtual’ displacement of a structure. It is a foundational concept in the principle of virtual work, which engineers use to analyze structural stability, calculate deformations, and determine whether a system is in equilibrium.
External venting – These are the holes which prevent high-pressure gas build-up in enclosed fabrications dipped in the molten zinc of the galvanizing bath.
External wear liner – It consists of a protective layer applied to the equipment components exposed to external wear, needing regular inspections and replacement as needed.
Extinction coefficient – It is the ratio of the diffracted beam intensity when extinction is present to the diffracted beam intensity when extinction is absent. It applies to primary or secondary extinction.
Extinction – It is a decrease in the intensity of the diffracted beam caused by perfection or near perfection of crystal structure.
Extinction coefficient – It is the sum of scattering and absorption by particles and gases in the atmosphere, measuring the alteration of radiant energy as it passes through. It is particularly useful for assessing visibility impairment because of the pollutants along the line of sight between an observer and a distant object. It describes how strongly a substance absorbs or scatters electro-magnetic radiation (such as light) at a specific wave-length.
Extinction ratio – It is a metric used mainly in photonics and optical communications to measure the contrast and purity of a light signal. It measures either the power ratio between digital data states or the purity of a polarized light source.
Extinction time – It is the specific moment or duration t at which a dynamic system’s state variables (like energy, or amplitude) decay entirely to zero. It evaluates how quickly a process terminates, burns out, or settles completely.
Extinguishing agent – It is any substance or medium designed to suppress or extinguish a fire by interrupting the combustion process. Agents work through four main mechanisms namely cooling, smothering (oxygen displacement), starvation (fuel removal), or chemical inhibition (breaking the chain reaction).
Extracted binder – it refers to the bituminous adhesive (asphalt) which has been chemically separated from its aggregate in an asphalt mixture or pavement sample. This separation process allows engineers to evaluate the binder’s original properties, test for aging, and determine if it meets binder specification standards.
Extracted compound – It refers to a target solute which has been isolated from a raw material (like a ore, or liquid mixture) using a specific separation process.The isolation relies on differences in chemical properties, such as relative solubility or volatility, between the target compound and the rest of the mixture.
Extracted core – It refers to a cylindrical sample of material (like rock, soil, asphalt, or concrete) removed from a structure or geological formation using a specialized drill bit. It is retrieved to preserve the material’s internal structure and evaluate its properties, such as compressive strength and density.
Extracted skeleton – it refers to the process of reducing a complex, higher-dimensional object (such as a 3D mesh, 2D image, or spatial network) into a simplified, low-dimensional centre-line or frame-work which preserves the object’s important topological features and geometry.
Extracting medium – It is also called extractant. It is the solvent, fluid, or gas used to selectively dissolve, separate, or concentrate specific target compounds from a solid or liquid mixture. It is the active agent which drives liquid-liquid, solid-liquid, or super-critical fluid extraction processes.
Extraction – It is a general term denoting chemical methods of isolating phases from the metal matrix. It is also extraction of ore from ore deposit. Ore is extracted from the earth through mining and treated or refined, often through smelting, to extract the valuable metals or minerals.
Extraction cell – It is a main component of solvent extraction-separation systems for rare earth elements, consisting of a mixing chamber and a phase separation chamber. It is designed to facilitate the mixing and separation processes important for extraction efficiency.
Extraction chromatography – It is a hybrid separation technique combining the high selectivity of liquid-liquid extraction with the multi-stage efficiency of column chromatography. A liquid extractant (or a solution of an extractant) is immobilized onto a solid, porous support material to act as the stationary phase, while a liquid mobile phase carries the sample through it.
Extraction condensing turbine – It is an industrial steam turbine which generates electricity while simultaneously extracting a portion of its steam at an intermediate pressure for external use. The left-over steam is routed to a condenser to complete the thermodynamic cycle.
Extraction curve – It refers to either the graphical representation of a chemical separation process (solute concentration over time) or the extraction of geometric data (feature lines or cross-sections) from 3D CAD models and point clouds.
Extraction plant – It is an industrial facility designed to separate and recover target chemical constituents or fluids from a raw material, such as minerals, using solvents, heat, or mechanical compression.
Extraction process – It is a separation technique which utilizes differences in solubility to solubilize and separate a solute from other materials, typically involving methods such as solid-liquid extraction and liquid-liquid extraction. It is a mass-transfer unit operation used to separate a desired substance (solute) from a mixture by transferring it into a different phase or solvent. It relies on differences in solubility, volatility, or chemical affinity rather than heat alone.
Extraction ratio – It measures the fraction or proportion of a target material (like solute, or raw resource) removed from an inlet source into an output.
Extraction turbine – It is a type of steam turbine designed with one or more openings (extraction points) which allow steam to be extracted at various intermediate pressures. This extracted steam can then be used for industrial processes like heating, feedwater heating, or other applications.
Extractive content – It normally refers to non-structural, low-molecular-weight components, such as fats, waxes, resins, and phenolic compounds, found within materials like biomass. In software, it refers to systems that extract key statements directly from data.
Extractive distillation – It is a method for separating zeotropic and azeotropic mixtures by utilizing an entrainer to selectively improve the relative volatility of components, allowing for the separation of lighter components as a top product while heavier components exit with the solvent.
Extractive distillation column – In this column the separation of non-aromatics contained in the feed is carried out, which is not possible under normal distillation conditions. The non-aromatics originally with boiling points higher than aromatics, are converted into low boiling non-aromatics which can be withdrawn at the top of the column while the aromatic substances dissolve in the N-formylmoropholine (NFM) is yielded at the bottom of the column.
Extractive distillation unit – In this unit, the BTXS (benzene, pure toluene, xylene, and solvent oil) raffinate is processed to separate benzene, toluene, xylene, and solvent. Further benzene and toluene are also separated. N-formylmoropholine (NFM) is used as solvent for the separation of BTX (benzene, toluene, xylene) into BT (benzene and toluene) and ‘X’ (xylene). Non aromatic compounds present in BTXS (benzene, toluene, xylene, and solvent oil) are removed by pressure distillation as solvent which is recovered in solvent recovery column. Benzene and toluene are separated in BT (benzene and toluene) separation column. The objective of the extractive unit is to separate non aromatics from benzene and toluene. This unit produces pure benzene, pure toluene, xylene, and light solvent oil along with still bottom oil from BTXS (benzene, toluene, xylene, and solvent oil) raffinate.
Extractive fermentation – It is the incorporation of liquid–liquid extraction with liquid biphasic systems to extract products simultaneously as they form, thereby overcoming product inhibition and low productivity while simplifying purification stages.
Extractive metallurgy – It is the branch of process metallurgy dealing with the winning of metals from their ores.
Extractor – It is a device, machine, or tool designed to remove, pull out, or separate a substance, object, or component from something else. It is normally used in industrial contexts to withdraw materials through mechanical, chemical, or physical means.
Extra deep drawing steel – It is a superior quality of low carbon deep drawing steel.
Extrados – It is the exterior, convex curve or upper surface of an arch. It is a fundamental term in architecture and structural engineering, normally used to describe the ‘back’ of an arch.
Extra hard – It is a temper of non-ferrous alloys and some ferrous alloys characterized by values of tensile strength and hardness about one-third of the way from those of full hard to those of extra spring temper.
Extra-high voltage – It refers to power systems operating at nominal voltages between 330 kilo-volts and 1,000 kilo-volts. Extra-high voltage (EHV) lines act as the electrical inter-state highways, designed to efficiently transmit bulk electricity over long distances from generation sites to major urban and industrial centres.
Extra-high voltage (EHV) power transmission – It refers to bulk electricity transmission operating in the range of 345 kilo-volts to 800 kilo-volts). These extreme voltages are utilized to transport massive quantities of generated power over long distances with minimal losses, considerably reducing conductor material requirements and infrastructure costs.
Extrapolation – It is the mathematical and statistical method of estimating an unknown value which falls outside the range of known, observed data points. It extends existing trends (e.g., historical sensor readings, stress test results) to predict future outcomes or untested operational limits. It is used for forecasting system behaviour, evaluating material durability, and predicting component life-spans. Since it relies on the assumption that past or current patterns continue uninterrupted, it carries a higher margin of error than interpolation (which estimates between known data points).
Extrapolation distance – It is a boundary condition parameter used mainly in neutron transport (nuclear engineering) and radiation physics. It is defined as the distance beyond the physical boundary of a medium (such as a reactor core) where the mathematical neutron flux is assumed to theoretically drop to zero.
Extrapolation method – It is a statistical and mathematical method used to estimate unknown values or predict future outcomes which fall outside the range of the known data. It works by extending observed trends or patterns under the assumption that the underlying relationship continue beyond the measured dataset.
Extra fuel – It typically refers to supplementary fuel carried for safety reserves, weight buffers, or to chemically alter combustion characteristics. It means intentionally running an engine with a rich mixture (a lower air-to-fuel ratio). The excess fuel does not burn completely but instead absorbs heat through vapourization, acting as an internal coolant. This process protects turbine blades or engine cylinders from extreme thermal stress and suppresses engine knock.
Extra spring – It is a temper of non-ferrous alloys and some ferrous alloys corresponding approximately to a cold-worked state above full hard beyond which further cold work does not measurably increase strength or hardness.
Extremal – It refers to a mathematical function, curve, or solution which optimizes a system by achieving a maximum or minimum value. It is foundational in calculus of variations, where engineers seek pathways (like minimum energy or shortest time) that satisfy specific constraints.
Extremal curve – It is a path or trajectory which optimizes a specific system or process. It acts as the ultimate boundary, balancing opposing constraints to achieve a goal like minimizing time, reducing energy consumption, or maintaining structural stability.
Extremal points – These are the intersection of the three implicit surfaces. The notions of extremal lines and extremal points are closely related to the notion of corner points, in 2D images.
Extremal trajectory – It is a path which satisfies the necessary conditions for optimality. Derived using the calculus of variations or the Pontryagin maximum principle, it represents a candidate trajectory where a system’s performance index (like time, energy, or fuel) is at a local maximum or minimum.
Extreme compression fibre – It is the specific theoretical line or layer of material furthest from the neutral axis in a beam’s cross-section which experiences the maximum compressive stress during bending.
Extreme displacement – It normally refers to either the total physical distance a structure deflects under maximum stress or the total volumetric capacity of an engine or pump. It defines the maximum deflection or spatial translation of a structure, foundation, or rock mass from its original resting position under extreme loading or seismic activity.
Extreme learning machine – It is a type of single-hidden-layer feed-forward neural network (SLFN). It dramatically speeds up training by randomly assigning input weights and biases, and mathematically calculating output weights using the Moore-Penrose generalized inverse, bypassing traditional, iterative gradient descent.
Extreme point – It is a location within a convex set which cannot be expressed as a linear combination of any other two distinct points in that same set. In practical terms, these are the vertices, corners, or boundaries of a system’s feasible region.
Extreme pressure (EP) additives – These are additives for lubricants with a role to decrease wear of the parts of the gears exposed to very high pressures. These additives are usually used under heavier loads, at high temperatures and low speeds to prevent catastrophic failure or seizing of the application. Common examples of extreme pressure additives are molybdenum disulfide, graphite, sulphurized olefins and di-alkyl-di-thiocarbamate complexes. extreme pressure additives are also added to cutting fluids for machining of metals.
Extreme-pressure layers – These are protective, sacrificial films formed on metal surfaces under high-load, high-temperature, or extreme sliding conditions. These layers are created through the thermochemical reaction of extreme-pressure (EP) additives (containing sulphur, phosphorus, or chlorine) with metal surfaces when the standard lubricating oil film breaks down, typically preventing welding, scoring, and excessive wear.
Extreme-pressure (EP) lubricant – It is a lubricant which imparts increased load-carrying capacity to rubbing surfaces under severe operating conditions. Extreme-pressure lubricants normally contain sulphur, halogens, or phosphorus. The term anti-scuffing lubricant has been suggested as a replacement for extreme-pressure lubricant.
Extreme-pressure lubrication – It is a condition of lubrication in which the friction and wear between two surfaces in relative motion depend upon the reaction of the lubricant with a rubbing surface at elevated temperature.
Extreme programming – It is an agile software development methodology which emphasizes a high degree of responsiveness to evolving customer demands. Development cycles in extreme programming are short, and releases are frequent. Its main features include high-volume communication with customers and pair programming.
Extreme ultra-violet lithography – It is an advanced photo-lithography technique used in semi-conductor manufacturing to print ultra-fine circuit patterns onto silicon wafers. By utilizing extreme short-wave length light (13.5 nano-meters), it allows engineers to create transistor features below 5 nano-meters driving modern computing power. Extreme ultra-violet (EUV) is an important departure from older deep ultra-violet (DUV) methods and needs a completely different approach to optics and engineering.
Extremum point – It is a point in a system’s domain where a variable or function achieves its absolute or relative maximum or minimum value. These points are used to identify critical limits like peak loads, optimum material usage, and minimum energy states.
Extremum seeking control – It is a model-free, real-time adaptive optimization algorithm used in control engineering to automatically find and maintain the optimal operating point (maximum or minimum) of a performance function without needing a mathematical model of the system. The controller achieves this optimization through a continuous, four-step process consisting of modulation, system response, demodulation, and parameter update.
Extrinsic contribution – It refers to any property, response, or behaviour which originates from external factors or structural imperfections rather than the base material’s inherent (intrinsic) atomic lattice.
Extrinsic healing – It refers to a self-repair process in materials (such as polymers, asphalt, or composites) which relies on pre-packaged, external healing agents embedded within the material’s matrix. When damage occurs, these agents are released to mend the crack.
Extrinsic inclusion – It is also called exogenous inclusion. It is a type of non-metallic impurity in steel which originates from outside sources, rather than forming inside the melt through chemical reactions.
These inclusions are typically introduced into the molten metal during the processing stages, such as tapping, transferring, or casting, because of the mechanical or chemical erosion of materials.
Extrinsic parameters – These parameters define the spatial position and orientation of a sensor, like a camera or light detection and ranging (LiDAR) relative to an external, fixed world coordinate system or to another sensor. These parameters mathematically map where the sensor is located in the physical environment.
Extrinsic point defect – It is a zero-dimensional irregularity in a crystal lattice caused by the presence of foreign, impurity, or solute atoms. Unlike intrinsic defects (which occur naturally in pure materials), extrinsic defects result directly from the addition of foreign elements.
Extrinsic property – Extrinsic property is not essential or inherent to the subject that is being characterized. For example, weight is an extrinsic property which depends on the strength of the gravitational field in which the object is placed.
Extrinsic semi-conductor – It is a pure (intrinsic) semi-conductor material intentionally doped with trace impurities to dramatically increase its electrical conductivity and control its electrical properties. These materials form the basis of modern electronics, with doping producing either n-type (donor) or p-type (acceptor) material.
Extrinsic sensor – It is a device where the sensing process occurs outside the main transducer or transmission medium. The medium (like an optical fibre) serves purely to carry or relay the signal to and from an external sensing element.
Extrinsic workability – It refers to the ability of a material to be shaped or deformed, dictated by external process conditions rather than the internal metallurgical properties of the material itself. This defines how the surrounding environment, such as temperature, stress state, and lubrication, affects the ease of forming without cracking.
Extrudability – It is the measure of a material’s capacity to be forced, pushed, or drawn through a die, nozzle, or orifice under pressure. It determines how easily a material, such as metal, plastic, or gel flows and holds its shape without surface defects.
Extrudate – It is the final, continuous product which results from an extrusion process. It is formed by forcing raw material (like heated metal or molten plastic) under high pressure through a shaping orifice known as a die. The extrudate takes on the fixed cross-sectional profile of the die and is typically cut into standardized lengths or spooled for downstream applications.
Extrudate temperature – It refers to the actual temperature of the material (polymer, or metal) as it exits the die during an extrusion process. It is a critical parameter for quality control, influenced by viscous shear, friction, and heat application, and it determines the final product’s micro-structure, viscosity, and expansion.
Extruded aluminum alloys – These are versatile materials shaped by forcing heated alloy billets through a die to create complex profiles, normally using 6xxx series alloys for their high strength-to-weight ratio and corrosion resistance. These profiles are widely used in construction, automotive, and industrial applications for their stability, durability, and customization potential.
Extruded copper alloys – These are metal products created by forcing heated copper-based alloys (such as brass or bronze) through a shaped die to produce long, continuous, and complex solid or hollow cross-sections. This hot-working process produces durable, high-precision shapes with excellent thermal / electrical conductivity, normally used for architectural, automotive, and electrical applications.
Extruded filament – It is a continuous strand of material (typically thermoplastic, metal, or ceramic) created by forcing a softened or melted material through a shaped opening called a die. This manufacturing process is fundamental to producing raw spooled wire for material extrusion 3D printing and synthetic fibres.
Extruded hole – It is a hole formed by a punch which first cleanly cuts a hole and then is pushed farther through to form a flange with an enlargement of the original hole.
Extruded magnesium – It refers to magnesium alloys shaped by forcing a heated billet through a shaped die. This deformation process refines the metal’s grain structure, producing high-strength, light-weight structural components.
Extruded pipe – It is a continuous cylindrical product manufactured by forcing heated raw material, such as molten thermo-plastic polymers or heated metal billets, through a specialized annular die. The process defines both the outer diameter and inner wall thickness, creating seamless, uniform piping for different applications.
Extruded products – Extruded products are items created by forcing raw material, such as metal, or plastic, through a shaped opening, known as a die, to produce a continuous, uniform cross-sectional shape. This manufacturing technique is used to create items with consistent profiles, including tubes, pipes, rods, and structural frames.
Extruded profile design – It is the process of defining a specific, consistent cross-sectional shape, ranging from simple tubes to complex, customized geometries, which is produced by forcing heated material (such as aluminum or plastic) through a shaped die. This design method ensures that the cross-section remains uniform along its entire length, allowing for high-strength, lightweight, and customizable components utilized extensively in construction, automotive, and industrial applications.
Extruded profiles – These are long, continuous shapes created by forcing softened material, typically plastic or metal, through a customized die opening. The resulting products maintain a consistent cross-sectional geometry along their entire length. This manufacturing process produces intricate shapes used in construction, automotive, and industrial applications, including tubes, rods, and complex hollow or solid forms.
Extruded rod, bar, and wire – These are metal products formed by forcing a heated or unheated metal billet through a shaped die to create a specific, consistent cross-sectional profile. Rods and bars are stiff, structural forms used in manufacturing, while wire is a flexible, thin strand frequently produced by further drawing.
Extruded shapes – These are 3D objects or profiles created by forcing raw material, such as metal, or plastic, through a shaped die, resulting in long, continuous items with a consistent cross-section. This manufacturing process can be done through hot or cold methods to create solid or hollow forms like pipes, tubes, and custom profiles.
Extruded titanium alloy products – These are specialized structural components formed by forcing heated titanium alloy billets (typically a mix of titanium with elements like aluminum and vanadium) through a shaped die to create long, consistent cross-sections. This manufacturing technique is mainly used to produce complex shapes with high strength-to-weight ratios, corrosion resistance, and high-temperature performance, mainly for industries like high-performance automotive sectors.
Extruded tube – It is a semi-finished or finished tubular part created by forcing heated material (metal or plastic) through a die and around a mandrel. This thermo-mechanical process produces continuous tubes with precise cross-sectional profiles, uniform wall thickness, and highly consistent surface finishes.
Extruded tube and pipe – These are hollow, cylindrical, or shaped products created by forcing heated metal (like aluminum or steel) or plastic through a shaped die. This continuous manufacturing process ensures a uniform cross-section, precise wall thickness, and a smooth surface finish.
Extruder – It is a manufacturing machine which continuously pushes softened or molten materials through a shaped opening, known as a die, to create continuous products like pipes, tubing, films, or structural profiles. It transforms raw materials (such as pellets, powders, or billets) into uniform, finished geometries.
Extruding – It is the process of shaping material, typically plastic, or metal by forcing it under pressure through a shaped opening called a die. This manufacturing technique produces long, constant cross-section objects like pipes, tubes, or aluminum window frames. It is also forming of a flange around a hole in sheet metal.
Extrusion – 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 product and ram travel in the same direction. Also, there is relative motion between the extrusion stock and the die. In backward (indirect) extrusion, the die is at the ram end of the stock and the product travels in the direction opposite that of the ram, either around the ram (as in the impact extrusion of cylinders such as cases for dry cell batteries) or up through the centre of a hollow ram. It is also the pressure-induced distortion or extension of part of a seal into the clearance gap between mating seal surfaces.
Extrusion billet – It is a metal slug used as extrusion stock.
Extrusion blow moulding – It is an automated manufacturing process used to produce hollow thermo-plastic parts. It involves melting plastic resin, extruding it downward through a die to form a molten tube (a parison), capturing it inside a cooled metal mold, and inflating it with compressed air so it takes the mould’s shape.
Extrusion butt end defect – It is a longitudinal discontinuity in the extreme rear portion of an extruded product, which is normally discarded.
Extrusion (ceramics) – It is the process of forcing a mixture of plastic binder and ceramic powder through the opening(s) of a die at relatively high pressure. The material can hence be compacted and emerges in elongated cylindrical or ribbon (or wire, etc.) form having the cross section of the die opening. The process is normally followed by drying, curing, activating, or firing.
Extrusion coating – It is using a resin to coat a substrate by extruding a thin film of molten resin and pressing it onto or into the substrate, or both, without the use of an adhesive. It combines the distinct properties of both materials to create a high-performance composite used heavily in flexible packaging and liquid containers.
Extrusion conditions – These are the specific processing parameters, mainly temperature, pressure, screw speed, and feed rate, which control the deformation of materials through a die to produce consistent cross-sectional shapes. These conditions determine the final characteristics of the extrudate, such as its density, structural strength, moisture content, and shape.
Extrusion cooling systems -These are important downstream components in manufacturing which rapidly remove heat from molten plastic, rubber, or metal immediately after it exits the die. By transitioning the hot material from a molten to a solid state, these systems lock in the needed dimensional shape, prevent deformation, and ensure high-quality surface finishes.
Extrusion defect – The preferred term is extrusion pipe which is a central oxide-lined discontinuity which occasionally occurs in the last 10 % to 20 % of an extruded metal bar. It is caused by the oxidized outer surface of the billet flowing around the end of the billet and into the centre of the bar during the final stages of extrusion.
Extrusion die – It is a precision-engineered metal tool (typically steel) with a specific opening or channel through which heated material, such as metal, plastic, or rubber, is forced to create a continuous, fixed cross-sectional profile. It defines the final shape, accuracy, and external / internal profile of the extruded product.
Extrusion die material – Extrusion die is typically made from hardened hot work tool steel or specialized alloys. This material is to withstand high temperature, high pressure, and severe friction.
Extrusion, direct – Ij it a stem, normally with a pressure pad in front, pushes the billet in a stationary container through a tool of the desired shape, the die. Relative movement takes place between the billet and the container.
Extrusion direction – It defines the orientation of material flow through a die relative to the movement of the pressing ram. It dictates the process type, such as forward, backward, or radial, and directly impacts the friction, force needed, and the structural properties of the extruded part.
Extrusion effect – Extrusion results into textures which signify differences in the deformation behaviour in different directions. Hot-worked structure in the extruded sections contains elongated grains in the longitudinal direction. The mechanical properties in the longitudinal direction are higher than in the transverse direction. In extruded bars which have not completely recrystallized, e.g., high-strength aluminum alloys, the strength in the extrusion direction is higher than in the transverse.
Extrusion force – It is the total compressive load needed to push a raw work-piece (billet or powder) through a shaped die. It forces the material to undergo plastic deformation, transforming it into a continuous, reduced-size profile or component.
Extrusion forging – It is the forcing metal into or through a die opening by restricting flow in other directions. It is also a part made by the operation.
Extrusion, indirect – In it, the die is located in front of a hollow stem and pushed against the billet by the forward movement of the container closed at the back. There is, hence, no relative movement between the billet and the container.
Extrusion ingot – It is a cast metal slug used as extrusion stock.
Extrusion load – It is also called extrusion force. It is the total force needed to push a material (billet) through a die to reduce its cross-section. It is a critical parameter in manufacturing, representing the mechanical energy needed to overcome both the material’s deformation resistance and friction.
Extrusion log – It is the starting stock for extrusion billet. Extrusion log is normally produced in lengths from which shorter extrusion billets are cut.
Extrusion mandrel – It is a specialized, typically cylindrical metal tool used in the extrusion process to create hollow cavities or specific internal profiles in materials like metal, plastic, or rubber. It acts as a core or plug around which the material is forced, defining the inner diameter (ID) and shaping the internal void as the material passes through a die.
Extrusion, metals – It is the conversion of an ingot or billet into long lengths by forcing metal to flow through a die orifice. The cross section of the extrusion can be circular or highly irregular and specific in shape.
Extrusion moulding – It is a continuous manufacturing process where heated material (like plastic or metal) is forced through a shaped die to create long, uniform cross-sectional profiles. It is widely used to produce high volumes of items like pipes, tubes, window frames, and structural shapes.
Extrusion of iron-alloys – Iron alloys include steel and cast iron. It is a high-pressure, metal-forming manufacturing process which forces a solid, heated, or sometimes cold iron billet through a die of a desired cross-sectional shape. This process reduces the billet’s cross-sectional area and causes the metal to take on a new, consistent shape which is uniform over its entire length.
Extrusion of low-alloy copper material – It is a metal-forming manufacturing process where a heated billet of low-alloy copper is forced under high pressure through a die orifice to create long, solid, or hollow shapes with a constant cross-section. Low-alloyed copper materials are defined as copper alloys with total alloying element concentrations below 5 % (and frequently individual elements below 1 % to 2 %), which are designed to maintain high electrical and thermal conductivity while improving strength compared to pure copper.
Extrusion of powder metals – It is a manufacturing process which compacts, consolidates, and shapes metal powder into a solid, continuous profile by forcing it through a die aperture under high pressure. It combines powder metallurgy with extrusion to create dense, complex parts, often involving packing powder into a container (canning), heating, and extruding, followed by sintering.
Extrusion of semifinished products – It is an advanced manufacturing process used to create long, consistent, and continuous shapes by forcing raw material, typically plastic, rubber, or metal, under high pressure through a specially shaped die. It is considered a primary forming process in which the resulting extrudate (rod, tube, profile) needs further processing, such as cutting, finishing, or heat treatment, to become a finished product.
Extrusion parameters – These refer to the specific, controllable conditions and mechanical settings (e.g., temperature, speed, pressure) used during the extrusion process. These variables dictate how material is forced through a die to form specific shapes, directly determining the structural integrity, dimensions, and surface finish of the final product. The extrusion process is guided by several foundational parameters, broadly categorized into process settings, material variables, and tooling geometries.
Extrusion pipe – It is a central oxide-lined discontinuity which occasionally occurs in the last 10 % to 20 % of an extruded metal bar. It is caused by the oxidized outer surface of the billet flowing around the end of the billet and into the centre of the bar during the final stages of extrusion. It is also called coring.
Extrusion, plastics – It consists of compacting a plastic material into a powder or granules in a uniform melt and forcing it through an orifice in a more or less continuous fashion to yield a desired shape. While held in the desired shape, the melt is required to be cooled to a solid state.
Extrusion press – It is a machine which shapes metal, plastic, or other materials by forcing them through a shaped die, using high pressure to create a constant cross-section. These machines frequently use hydraulic systems to push heated materials (like aluminum billets) into specific profiles, ranging from simple tubes to complex, thin-walled shapes.
Extrusion pressure – It is the force per unit area applied by a ram to a material (billet or polymer) to force it through a die, shaping it into a specific cross-sectional profile. It is high-intensity force needed to overcome material deformation resistance and friction, typically ranging from 30 mega-pascals (MPa) to 700 mega-pascals in metal hot extrusion.
Extrusion principles – These are the principles which govern the effective functioning and precision of the extrusion process. Key principles include (i) the selection of materials which is important considering that the material is needed to soften or melt under determined conditions but without degradation, (ii) temperature control which is to be successfully held for the material to flow evenly through the die, (iii) die design since it defines the shape and dimensions of the extruded product and hence is to be very precise, (iv) consistency of pressure which is to be imposed on the material inside the extrusion barrel so as to ensure that the material does not suffer from defects during finishing, and (v) a proper cooling scheme for the extruded product while solidifying from the molten state of perfection so as not to impart any internal stress or warpage to the product. Following all these principles, extrusion can quickly and reliably produce high-quality custom components.
Extrusion process – Extrusion is a compressive deformation process in which a block of metal is squeezed through an orifice or die opening in order to get a reduction in diameter and increase in length of the metal block. The resultant product has the desired cross-section. Extrusion involves forming of axi-symmetric (symmetrical about an axis) products. Dies of circular on non-circular cross-section are used for extrusion. Extrusion normally involves high forming forces. Large hydrostatic stress in extrusion helps in the process by improving the ductility of the material. Metals like aluminum, which are easily workable, can be extruded at room temperature. Other difficult to work metals are normally hot extruded or warm extruded. Both circular and non-circular products can be achieved by extrusion. Channels, angles, rods, window frames, door frames, pipes tubes, and aluminium fins are some of the extruded products. Difficult to form materials such as steels, nickel alloys are extruded because of inherent advantage of the extrusion process, such as, no surface cracking because of reaction between the billet and the extrusion container takes place. Extrusion results in better grain structure, better accuracy, and surface finish of the components. Less wastage of material in extrusion is another attractive feature of the extrusion process.
Extrusion process limitations – These refer to the constraints and disadvantages inherent in manufacturing, where material is forced through a die to create uniform shapes. Key limitations include the need for a constant cross-section along the entire length, high initial tooling costs, limited material flexibility for complex shapes, and potential surface defects or dimensional variations.
Extrusion puller – It is a downstream machine used in manufacturing to continuously draw extruded material, such as plastics, rubber, or aluminum profiles, through a die, cooling tank, or curing unit. It ensures consistent speed and tension, preventing deformation and controlling the final dimensions of the product. The main purpose is to pull the material at a constant, controlled speed to maintain precise dimensions and quality. Typically, pullers use top and bottom tracks (belts) or wheels which grip the product, frequently powered by variable-speed servo drives to ensure synchronization with the extruder.
Extrusion rate – It is the quantity of material (plastics, metals, or paste) processed through a die over a specific period, normally measured in mass per time. It dictates the speed of production, with higher rates frequently needed for higher efficiency but potentially impacting material quality.
Extrusion ratio – It is the ratio of the cross-sectional area of the extrusion container to that of the extruded product.
Extrusion seam – It is a region in extruded hollow profiles observed after creating two streams of metal and rejoining them around the mandrel of a porthole or bridge die.
Extrusion speed – It is the velocity at which material (such as plastic, or metal) is forced out of the die exit during a manufacturing process. It is an important, controllable parameter which determines production efficiency, product quality, and surface finish, frequently measured in meters per minute.
Extrusion stock – It is a rod, bar, or other section which is used to make extrusions.
Extrusion temperature – It refers to the controlled thermal conditions of the material, container, and die during an extrusion process. It is carefully regulated to maintain plasticity, prevent microstructural defects, and achieve the desired mechanical properties and cross-sectional shape of the final product.
Extrusion texture – It refers to the preferred, non-random orientation of crystal grains which develops in a metal or alloy during the extrusion process. Since extrusion forces metal through a die under high pressure, the grains align along the deformation axis, resulting in a fibrous or directional micro-structure known as a fibre texture.
Extrusion tooling – It can be broadly classified into (i) tooling which is directly involved in the shape forming of the material being extruded, (ii) tooling which is not directly involved, and (iii) tooling which fulfills auxiliary and support functions. The first group includes extrusion dies, porthole and bridge dies, as well as mandrels. These extrusion tools come into direct contact with the billet material heated to the deformation temperature. The second group includes extrusion tooling which does not have any shape-producing function but, at the same time, is indirectly involved in the shape-changing process. This includes container liners, extrusion stems, dummy blocks, and mandrel holders as well as die-carrying stems, container-sealing plates, and container-sealing stems with sealing discs in indirect extrusion. The third group is represented by the auxiliary tooling, including die holders, tool holders, pressure plate holders, as well as support tooling including the container mantle, liner holder, and sub-bolsters and bolsters in the direct-extrusion tool stack.
Extrusion velocity – It is the speed at which a material is expelled or pushed through the die opening during the extrusion process. Measured in units like millimeters per second, it determines production output rates and directly influences the structural properties and surface quality of the final part.
Extrusion welding – It is a specialized welding technique used mainly for joining thermoplastics and composite materials. It involves using a hand-held extruder to melt a filler rod and deposit it as a molten bead into a preheated joint, creating a robust, watertight bond upon cooling.
Exudation – it is the action by which all or a portion of low melting constituent of a compact is forced to the surface during sintering. It is sometimes referred to as bleed out or sweating.
Ex Works – ‘Ex Works’ means that the seller delivers when it places the goods at the disposal of the buyer at the seller’s premises or at another named place (i.e. works, factory, warehouse, etc.). The seller does not need to load the goods on any collecting vehicle, nor does it need to clear the goods for export, where such clearance is applicable.
Eyebolt – It is a bolt featuring a looped head, designed for lifting or attaching components within the conveyor system, warranting inspections to validate proper installation and sustained structural integrity.
Eyehole – It is the region in which film is absent because of the non-wetting of the metal surface by the coating.
Eyeleting – It is the displacing of material about an opening in sheet or plate so that a lip protruding above the surface is formed.
Eyelet linkage (splice) – It is a sophisticated technique for securely joining the ends of a conveyor belt using a looped connection, needing adept installation and regular assessments to monitor wear and ensure ongoing security.
Eyelets – They are intended to be placed on the load either by threading or by welding for lifting it.
Eye-piece – It is a lens or system of lenses for increasing magnification in a microscope by magnifying the image formed by the objective.
Eytelwein equation – It is also known as the capstan equation or belt friction equation. It is used in several industries to analyze friction between a rope or belt and a cylindrical surface, like a pulley or capstan. It helps determine the relationship between the tension on either side of the wrapped rope or belt and the friction involved. This equation is crucial for understanding and designing systems involving power transmission, load holding, and braking mechanisms.
EZ logic – It means ‘Electronic Zero Pressure Logic’ for zero pressure accumulation conveyor systems.
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