Glossary of technical terms for the use of metallurgical engineers Terms starting with alphabet ‘N’
Glossary of technical terms for the use of metallurgical engineers
Terms starting with alphabet ‘N’
Nabarro–Herring creep (NH creep) – It is a mechanism of deformation of crystalline materials (and amorphous materials) which occurs at low stresses and held at high temperatures in fine-grained materials. In Nabarro–Herring creep, atoms diffuse through the crystals, and the rate of creep varies inversely with the square of the grain size so fine-grained materials creep faster than coarser-grained ones. Nabarro–Herring creep is solely controlled by diffusional mass transport. This type of creep results from the diffusion of vacancies from regions of high chemical potential at grain boundaries subjected to normal tensile stresses to regions of lower chemical potential where the average tensile stresses across the grain boundaries are zero.
NACE International – It is a professional organization for the corrosion control industry which publishes papers articles and standards on all aspects of corrosion and has written the definitive standard for valve materials for sour gas service. It has been formerly known as the National Association of Corrosion Engineers.
Nacelle – It is the housing which is located on top of the tower, behind the rotor blades. It encloses the key components which convert wind energy into electricity, including the generator, gearbox, brake, and internal equipment. It protects the internal components of the turbine from the surrounding environment.
Nail, chill – It consists of steel nail with a heavy head which is inserted in the mould wall to hasten cooling of the metal at that point.
Nails – These are fasteners consisting of a smooth cylindrical-shaped piece of metal. They have a sharp point on one end and a flat head on the opposite end.
Name-plate capacity – It is also known as the rated capacity, nominal capacity, installed capacity, maximum effect or gross capacity. It is the designed output of a facility. Nameplate capacity is the intended full-load sustained output of a facility such as a power station, electric generator, a chemical plant, fuel plant, mine, metal refinery, and several others.
Nano-additives – These are materials at the nano-scale (with at least one dimension less than 100 nano-meters) that are incorporated into other materials or systems to enhance their properties. These additives, which can include nano-oxides, carbon-based nano-materials like graphene, and several other nano-particles, improve characteristics such as strength, lubricity, barrier properties, and combustion efficiency in applications ranging from packaging and fuels to machining.
Nano-cellulose film – It is a thin, flat, and foldable material mainly composed of nano-fibres of cellulose. It is formed from nano-cellulose, a nano-material with dimensions between 1 nano-meter and 100 nano-meters, which creates a dense network of nano-fibres. These films possess beneficial properties like high mechanical strength, good thermal stability, low gas permeability, and optical transparency, making them suitable for applications such as packaging, and electronic devices.
Nano-clays – These are fine-grained, naturally occurring, or synthetic layered silicate minerals whose particle size is in the nano-meter range (less than 100 nano-meter in at least one dimension). They possess a layered structure, typically consisting of sheets of silica tetrahedra and alumina octahedra, with replaceable ions trapped between the layers. These unique characteristics give nano-clays distinct thermal, mechanical, and barrier properties, making them useful in several applications like polymer composites, and even as a sustainable soil amendment.
Nano-coatings – These are thin films or layers applied to surfaces which have a thickness at the nano-scale, which can include nano-scale particles dispersed within a matrix. These coatings can improve properties such as physical stability, corrosion resistance, and mechanical strength, making them advantageous over traditional coatings in several applications.
Nano-composite – It is a composite material made from at least two distinct phases, where at least one of the phases has a nano-scale morphology (dimensions in the range of 1 nano-meter to 100 nano-meters). These materials are engineered by combining components to achieve new properties which are considerably different and frequently superior to those of the individual constituent materials, because of their large surface area and specific interfacial characteristics.
Nano-composite hydrogels – These are also called hybrid hydrogels. These are highly hydrated polymeric networks, either physically or covalently crosslinked with each other and / or with nano-particles or nano-structures. Nano-composite hydrogels can mimic native tissue properties, structure and micro-environment because of their hydrated and interconnected porous structure. A wide range of nano-particles, such as carbon-based, polymeric, ceramic, and metallic nano-materials can be incorporated within the hydrogel structure to get nano-composites with tailored functionality. Nano-composite hydrogels can be engineered to possess superior physical, chemical, electrical, thermal, and biological properties.
Nano-crystalline (NC) material – It is a polycrystalline material with a crystallite size of only a few nano-meters. These materials fill the gap between amorphous materials without any long-range order and conventional coarse-grained materials. Definitions vary, but nano-crystalline material is normally defined as a crystallite (grain) size below 100. Grain sizes from 100 nano-meters to 500 nano-meters are typically considered ‘ultra-fine’ grains. The grain size of a nano-crystalline sample can be estimated using X-ray diffraction.
Nano-crystalline metals – These are defined as single or multi-phase poly-crystalline solids with grain sizes typically less than 100 nano-meters characterized by a high density of interfaces which can considerably alter their mechanical and physical properties compared to conventional micro-crystalline metals.
Nano-crystallization – It is a process of producing nano-crystals, which are crystalline particles with a size on the nano-meter scale (less than 1 micro-meter). This technique is widely used to increase the solubility and dissolution rate of poorly soluble materials, improving their availability. It can be achieved through several methods, including wet milling, high-pressure homogenization, and other top-down own or bottom-up techniques, which reduce particle size to the nano-scale.
Nano-diamonds – These are engineered carbon nano-materials with a core of diamond-like sp3 hybridized carbon atoms and an outer shell of graphitic sp2 carbon, possessing a particle size under 100 nano-meters. Their unique core-shell structure, high surface area, excellent mechanical and thermal properties make them valuable for applications such as reinforcing polymer composites, and creating functional coatings for electronics and sensors.
Nano-electro-mechanical system (NEMS) – It is a device which integrates electrical and mechanical functionalities on the nano-scale, typically with dimensions in the nano-meter range. These devices combine nano-scale electronics, such as transistors, with mechanical components like actuators, pumps, or resonators to create highly sensitive sensors for detecting physical, or chemical entities. Nano-electro-mechanical systems show unique properties such as high sensitivity, low power consumption, and the ability to perform tasks with nano-scale precision, making them useful in fields like environmental sensing, and advanced electronics.
Nano-electronics – It is a field of engineering and applied science that uses nano-technology to design, create, and study electronic components and systems at the nano-scale, typically from 1 nano-meter to 100 nano meters. At this size, materials display quantum mechanical properties which differ from classical physics, enabling the development of smaller, faster, and more energy-efficient devices such as advanced memory chips and sensors found in modern technology.
Nano-emulsions – These are defined as fine, stable, and normally optically clear dispersions of two immiscible liquids (oil-in-water or water-in-oil) which are stabilized by an amphiphilic surfactant, with droplet sizes less than 300 nano-meters. Their small droplet size contributes to long-term physical stability by mitigating destabilization phenomena such as sedimentation, creaming, and coalescence.
Nano-engineering – It is the practice of engineering on the nano-scale. It derives its name from the nano-meter, a unit of measurement equaling one billionth of a meter. Nano-engineering is largely a synonym for nano-technology, but emphasizes the engineering rather than the pure science aspects of the field.
Nano-fabrication processes – These refer to the manufacturing techniques used to create nano-scale devices, typically involving two main stages namely the formation of an image on a material’s surface and the subsequent processing and patterning of that surface. These processes are normally applied in fields such as micro-electronics and nano-photonics.
Nano-ferrites – These are ferrite materials, which are ceramic ferromagnetic compounds of iron oxide and other metals, with at least one structural dimension in the nano-meter scale (typically less than 100 nano-meters). These nano-structured ferrites are engineered to exploit their improved surface-to-volume ratio and quantum size effects, leading to unique chemical, magnetic, electrical, and optical properties which differ considerably from their bulk counter-parts. This allows them to be used in diverse applications, such as high-performance sensors, and catalysts.
Nano-fibres – These are ultra-fine, one-dimensional fibres with diameters typically less than 1000 nano-meters, possessing unique properties like a high surface-area-to-volume ratio, high porosity, and excellent mass transport properties because of their small scale. These properties stem from the precise alignment of molecules or atoms within the fibre structure, making them suitable for different applications such as filtration, and protective clothing.
Nano filter – It is also called nano-filtration membrane. It is a pressure-driven filter with pore sizes typically between 1 nano-meter to 10 nano-meters used to separate dissolved molecules from water and other solutions. It operates between ultra-filtration and reverse osmosis, selectively removing divalent ions (like calcium and magnesium for water softening), organic matter, and smaller particles, while allowing smaller mono-valent ions and water to pass through. Nano-filters are widely used in water treatment for purification and separation applications.
Nano-filtration – It is a membrane filtration process which uses nano–meter sized pores through which particles smaller than around 1 nano-meter to 10 nano-meters pass through the membrane. Nano-filtration membranes have pore sizes of around 1 nano-meter to 10 nano-meters, smaller than those used in micro-filtration and ultra–filtration, but a slightly bigger than those in reverse osmosis. Membranes used are predominantly polymer thin films. It is used to soften, disinfect, and remove impurities from water.
Nano grains – These are the tiny crystalline structures which make up nano-crystalline materials, with individual grain sizes typically less than 100 nano-meters. The term ‘nano’ signifies a scale of one billionth of a meter. These materials possess unique mechanical, optical, and magnetic properties which differ considerably from conventional coarse-grained materials, largely because of the high proportion of atoms located at the grain boundaries, which are interfaces between the nano grains.
Nano hardness – It is a material’s resistance to plastic deformation at the nano-scale, measured by applying a very small force with a sharp indenter (like a diamond tip) to create a shallow indentation, typically less than 50 nano-meter deep. This technique, known as nano-indentation, uses the resulting load-displacement curve to calculate the mean contact pressure, or hardness. It is crucial for assessing the mechanical properties of thin films, nano-scale structures, and individual micro-constituents.
Nano-hardness test – It is an indentation hardness testing procedure, normally relying on indentation force against tip displacement data, to make assessments of the resistance of surfaces to penetrations of the order of 10 nano-meters to 1,000 nano-meters deep. The prefix ‘nano-’ normally implies hardnesses one thousand times smaller than ‘micro-hardness’, however, use of this prefix has been primarily designed as a means to distinguish this technique from the more traditional micro-indentation hardness procedures. Majority of the nano-hardness testing procedures use three-sided pyramidal diamond indenters first described by Berkovich.
Nano-inverter – It is the grid tied inverters rated less than 100 watts. It is useful for connection of single solar photo-voltaic (PV) panels to a building alternating current power system.
Nano-lithography – It is a nano-fabrication technique used to create patterns with nano-scale dimensions, typically ranging from 1 nano-meter to 100 nano-meters. It involves using different methods like optical lithography, electron beam lithography, and nano-imprint lithography to precisely define structures on materials, frequently light-sensitive ones, for applications in fields such as semi-conductor manufacturing, and electronics.
Nano-manufacturing system – It is the collection of processes, technologies, and specialized equipment used for the commercially-scalable, reliable, and cost-effective production of nano-scale materials, devices, and systems, where components are engineered with dimensions between 1 nano-meter to 100 nano-meters. These systems are the practical application of nano-technology, bridging nano-science discoveries with real-world applications by producing products with unprecedented precision and functionality at the molecular level.
Nano-material – In ISO/TS 80004, nano-material is defined as the ‘material with any external dimension in the nanoscale or having internal structure or surface structure in the nano-scale’, with nano-scale defined as the ‘length range approximately from 1 nano-meter to 100 nano-meter’. This includes both nano-objects, which are discrete pieces of material, and nano-structured materials, which have internal or surface structure on the nano-scale. A nano material can be a member of both these categories.
Nano-materials characterization – It is the use of advanced techniques to identify the unique physical and chemical characteristics of nano-materials, including their structure, surface morphology, and molecular properties, which are necessary for evaluating their performance and safety in different applications.
Nano-materials technology – It is the field concerned with engineering, applying, and manipulating materials at the nano-scale (typically 1 nano-meter to 100 nano-meters) to exploit their unique physical, chemical, and other properties, which differ considerably from their bulk counterparts because of the high surface-area-to-volume ratios and quantum effects. These properties enable applications across different sectors, including packaging, and electronics.
Nano-material types – These refer to the different categories of nano-materials, such as carbonaceous nano-materials and metal oxides, which influence their processing and recycling strategies based on their composition and form in waste materials.
Nano-mechanics – It refers to the study of the mechanical properties and behaviours of materials and structures at the nano-scale, focusing on the size-dependent responses and physical characteristics of nano-structures. It is an emerging field of research which holds substantial technological importance.
Nano-metallurgy – It is the study of metals on a nano scale.
Nano-meter (nm) – It a unit of length in the International System of Units (SI), equal to one billionth part of a meter (0.000,000,001 meter) and to 1,000 picometres. One nano-meter can be expressed in scientific notation as 1/1,000,000,000 meter.
Nano-metrology – It is the science of measurement at the nano-scale level, encompassing the evaluation of dimensions, chemical composition, nano-particle concentrations, and different physical properties of nano-materials, typically under 100 nano-meters in size. It needs high precision measurements and the establishment of new standards because of the unique properties of nano-scale objects.
Nano-particle reinforcement – It is the process of adding nano-particles to a material, such as a polymer or cement, to considerably improve its mechanical and physical properties, like strength and stiffness. The high surface area to volume ratio of nano-particles allows for strong interactions with the surrounding material matrix, which restricts the movement of polymer chains, strengthens the material, and improves overall performance.
Nano-particles – These are extremely small particles, typically ranging from 1 nano-meter to 100 nano-meters in size. A nanometer is one billionth of a meter, making these particles considerably smaller than what the naked eye can perceive. Their small size gives them unique properties, making them useful in a wide range of applications.
Nano-particle surface – It refers to the boundary of a nano-particle, a particle with at least one dimension in the nano-scale (typically 1 nano-meter to 100 nano-meters. Because of its small size, a nano-particle has a high surface area to volume ratio, which results in unique chemical and physical properties different from bulk materials. This extensive surface is critical for its application.
Nano-platelet – It is a nano-scale platelet-shaped material with atomically precise, extremely thin layers, such as semi-conductor sheets or stacked graphene layers. These nano-materials show unique optical properties, high quantum yields, and very good electrical and thermal conductivity, making them valuable in applications like displays, energy storage, and high-performance composites.
Nano-pore – It is an opening on the nano-scale, typically less than 100 nano-meters in diameter, formed within a thin membrane. It can be a man-made hole in synthetic materials like silicon or graphene. Nano-pores act as pathways for molecules, and by monitoring the ionic current changes as molecules pass through, they are used as powerful tools for single-molecule detection and analysis.
Nano-powder – It is a powdered material consisting of individual particles with sizes in the nano-meter scale, typically ranging from 1 nano-meter to 100 nano-meters. Because of their extremely small size, nano-powders possess a very high surface area-to-volume ratio, which results in unique and improved physical, chemical, and mechanical properties compared to their larger-scale counterparts. These improved properties make them valuable in several fields, including electronics, and materials science.
Nano precipitates – These are exceptionally small particles of a secondary phase (a different chemical composition) which form within a host material (like a metal alloy) during specific heat treatments or processing, serving to strengthen the material by hindering dislocation movement, refining grain size, or even trapping impurities like hydrogen. These nano-scale particles act as ‘invisible speed bumps’ which make the material more resistant to deformation and improve its mechanical properties.
Nano-rheology – It is the study of the flow characteristics of matter at a very small scale, specifically focusing on the mechanical properties of viscoelastic materials and their strain-rate dependent viscosity. It involves measuring parameters such as storage modulus, loss modulus, and phase angle to characterize material behaviour under controlled conditions.
Nano roughness – It refers to surface irregularities and textures at the nano-meter scale, typically featuring heights or widths smaller than 100 nano-meters. These nanoscale features considerably influence a surface’s properties, affecting material properties like hydrophobicity and wear resistance. Atomic force microscopy (AFM) is a main tool for measuring nano-scale surface roughness because of its high spatial resolution.
Nano-scale – It is defined as the range of dimensions from 1 nano-meter to 100 nano-meters where materials show unique physico-chemical properties because of their small size.
Nano-scale effect – It is a unique physical or chemical property which a material shows when its dimensions are reduced to the nano-meter scale (typically 1 nano-meter to 100 nano-meters), causing quantum mechanical phenomena and a higher surface area-to-volume ratio to dominate over bulk material behaviour. These changes in properties, such as altered electrical conductivity, optical absorption, or chemical reactivity, enable a wide range of new technological applications.
Nano-scale electronic devices – These refer to electronic components and circuits which operate at the nanos-cale, characterized by their three-dimensional functionality and substantial advancements in micro-electronics. These devices are defined by their operational characteristics and are a result of key discoveries in device components and the technology used for their creation and characterization.
Nano-scale flow – It refers to the movement of fluids at the nano-scale, which is characterized by differences from traditional flow mechanics, including variations in surface behaviour and velocity.
Nano-scale friction – It is the frictional force which arises from the interaction of surfaces at the atomic or nano-meter scale, considerably influencing macroscopic friction in nano-devices and systems. Unlike macroscopic friction, nano-scale friction is not independent of the contact area and is studied using techniques like atomic force microscopy (AFM) to observe and manipulate forces with high precision.
Nano-scale material – It refers to materials which incorporate reinforcements or fillers at the nano-scale, such as nano-particles or nano-fibres, which improve the properties of the final composite material, including mechanical strength, stiffness, and thermal or electrical conductivity. These materials can be customized for different applications by altering the type, size, form, and concentration of the nano-scale components.
Nano-scale roughness – It refers to the surface texture characterized by features at the nano-scale, which can considerably improve the hydrophobic properties of a substrate through engineered surface modifications. This type of roughness is frequently combined with micro-level textures to optimize super-hydrophobic characteristics.
Nano-scale topography – It defines the specific surface features of a material at the nano-meter scale (around 1 nano-meter to 100 nano-meters). It describes the size, shape, and spatial organization of surface elements like ridges, pores, or grooves. This intricate surface detail considerably influences the material’s properties.
Nano-second (ns) – It is a unit of time in the International System of Units (SI) equal to one billionth of a second, that is, 1/1,000,000,000 of a second.
Nano-sensors – These are sensors which utilize the unique properties of nano-materials to detect and measure physical quantities, such as temperature and humidity, at the nanoscale. Their detecting capacity is limited to the nearby nano-context, necessitating multiple nano-sensors for broader coverage.
Nano-silver particles – These are silver materials with at least one dimension less than 100 nano-meters, showing unique physical, and chemical properties because of their extremely high surface-area-to-volume ratio. This increased surface reactivity and unique quantum mechanical effects make them highly valuable in engineering for applications like improving thermal conductivity, improving solar cell efficiency, and developing advanced electronic components.
Nano-steel – It is a type of third generation AHSS (advanced high strength steel) which is still under development. This steel is not yet commercialized. This steel has a nano-crystalline structure created by special chemistry and heat treatment. After casting, the steel is mainly austenite with some borides. After heat treatment, austenite is refined to nano-meter scale. During the plastic deformation, stress induced nano-scale phase formation increases strain hardening.
Nano-structured coating – It is a coating which utilizes nano-structured feedstock powder to achieve improved properties, such as increased fracture toughness, through processes like high-velocity oxygen fuel (HVOF) spraying, suspension plasma spraying, or solution precursor plasma spraying.
Nano-structured fillers – These refer to materials, such as metal oxides and clays, which are incorporated into membranes to improve their physico-chemical properties and functionalities through surface modification. These fillers improve membrane performance by altering its surface and morphology.
Nano-structured surfaces – These are the surfaces with structured components which have at least one dimension in the range of less than 100 nano-meters, which are engineered to improve understanding of molecular interactions.
Nano-structured metal surfaces – These are surfaces of materials where the structural features have dimensions on the scale of nanometers (1 nano-meter to 100 nano-meters). These surfaces show unique properties because of the reduced size and high surface area compared to bulk materials. Nano-structuring can be achieved through different methods, including lithography, etching, and deposition techniques.
Nano-structures – These are materials or objects with at least one dimension measuring between 1 nano-meter to 100 nano-meters. They can have one, two, or three dimensions on this nano-scale, such as nano-textured surfaces (one dimension), nano-tubes (two dimensions), and nano-particles (three dimensions). The study and application of nano-structures are the main focus of nano-technology, with researchers exploring their unique mechanical, electrical, optical, and other properties to develop new technologies across several fields.
Nano-systems – These refer to systems engineered at the nano-scale, where materials can be specified and produced with exact properties, enabling innovative design and functionality which considerably differ from traditional engineering practices.
Nano-technology – It is the manipulation of matter with at least one dimension sized from 1 nano-meter to 100 nano-meters. At this scale, surface area and quantum mechanical effects become important in describing properties of matter. This definition of nano-technology includes all types of research and technologies which deal with these special properties.
Nano-titanium di-oxide – It is titanium di-oxide (TiO2) in particle form with a diameter of less than 100 nano-meters. This nano-scale size gives it a much larger surface area compared to conventional titanium di-oxide, resulting in unique properties like improved photo-catalytic, ultra-violet absorption, and electrical characteristics. These properties make it useful in applications such as sun-screens, coatings, and electronics.
Nano-tesla (nT) – A nano-tesla is an extremely small unit of magnetic flux density, or magnetic field strength. in the International System of Units (SI). A nano-tesla is a SI-multiple (see prefix nano) of the magnetic flux density unit tesla and equal to one billionth of a tesla (0.000,000,001 T). It is used to measure very weak magnetic fields.
Nano-tribology – It is the study of friction, wear, and lubrication at the atomic and molecular scale, investigating phenomena like adhesion, contact mechanics, and surface interactions at the nano-scale. This field utilizes techniques such as ‘atomic force microscopy’ (AFM) and molecular dynamics simulations to characterize and modify surfaces, aiming to control tribological behavior for applications in micro-scale and nano-scale devices and the development of new materials like self-lubricating coatings.
Nano-tube – It is a tubular structure measured on the nano-meter scale (one-billionth of a meter) which shows extraordinary strength and conductivity. While they can be made from several materials, they are very frequently carbon nano-tubes (CNTs), which are cylindrical molecules of carbon atoms arranged in a hexagonal lattice, similar to rolled-up sheets of graphite.
Nano-wire – It is a solid wire-like nano-structure with a diameter typically ranging from 1 nano-meter to 100 nano-meters, and a length which is considerably higher than its diameter. At this nano-scale, quantum mechanical effects become prominent, influencing the material’s properties. Nano-wires can be made from several materials, including metals (like gold), semi-conductors (like silicon), and insulators. They are used in a variety of electronic and opto-electronic devices, such as transistors, diodes, and solar cells.
Naphtha – It is a flammable liquid hydro-carbon mixture. It is normally a fraction of crude oil, but it can also be produced from natural-gas condensates, petroleum distillates, and the fractional distillation of coal tar and peat.
Naphthalene – It is an organic compound with formula C10H8. It is the simplest polycyclic aromatic hydrocarbon, and is a white crystalline solid with a characteristic odor that is detectable at concentrations as low as 0.08 parts per million (ppm) by mass. As an aromatic hydro-carbon, naphthalene’s structure consists of a fused pair of benzene rings. It is the main ingredient of traditional mothballs.
Naphthalene oil – It is a liquid with a brown to dark brown colour. It is complex combination of hydro-carbons and consists primarily of aromatic and other hydro-carbons, naphthalene, phenolic compounds, benzo-thiophene, and aromatic nitrogen compounds. It has boiling range of 210 deg C to 220 deg C and solidifying point of 65 deg C to 75 deg C. It is a flammable liquid. It has a moth ball odour. Its flash point is 56 deg C to 81 deg C. The specific gravity is in the range of 0.987 to 0.993.
Naphthenes – These are also called cyclo-alkanes. These are saturated, cyclic hydrocarbons with the general formula CnH2n and one or more carbon rings, such as cyclo-pentane and cyclo-hexane. They are distinguished from straight-chain alkanes by their ring structure and are important feedstocks for producing high-octane gasoline and different solvents.
Napped cloth – It is a woven cloth in which some fibres are aligned approximately normal to one of its surfaces.
Narrow-band – It describes a system or signal which operates within a narrow range of frequencies, meaning it occupies a small bandwidth relative to the overall frequency spectrum. This characteristic is common in applications like radio communication, radio-frequency identification (RFID), and narrow band FM (frequency modulation for speech, where it enables better range and sensitivity by reducing noise and focusing on specific carrier frequencies.
Narrow-gap welding – It is used to describe processes that have been designed to reduce weld metal volume in butt welds, particularly in carbon and low-alloy steels. These processes are all mechanized. The cost benefits of narrow-gap welding result from its low energy and filler material costs, together with the shorter time needed to fill the considerably smaller weld volume. Other factors include less complicated joint preparation, reduced time at high working temperatures and less distortion of the work-piece because of the smaller volume of weld metal. Narrow-gap welding is suitable for joining sheet and plate in the 25 millimeters to 300 millimeters range. Joints to be welded are prepared with parallel sides or slightly U-shaped. Joints with parallel sides are cheap to prepare, although difficulties can arise as a result of contraction during welding, which has the effect of narrowing the remaining (unwelded) gap.
Narrow span of control – In organizational management, a narrow span of control refers to a management structure where a manager has a small number of direct reporting personnel. This means a manager oversees a smaller team of employees compared to a wide span of control, where a manager has several direct reporting personnel. A narrow span of control typically results in a more hierarchical structure with more layers of management within an organization.
Narrow nozzle – It is a constricted opening designed to control and direct the flow of a fluid, frequently accelerating its velocity and reducing its pressure. The term also refers to a specifically shaped welding torch head which accommodates a very thin weld groove to facilitate ultranarrow gap welding.
Narrow pulse – It refers to a signal with a very short duration, used in applications like spectroscopy for exciting spins or in circuitry to achieve higher resolution and faster operation. The main characteristic is a small width or duration, but this can result in broad excitation band-widths needing high power or, conversely, can be synthesized by combining multiple narrower sub-signals.
Narrow spectral linewidth – It refers to a laser or light source that emits light over a very limited range of wave-lengths, characterized by a small spectral width, frequently measured as ‘full width at half maximum’ (FWHM). This high spectral purity is crucial for applications like fibre-optic communications, optical atomic clocks, and gravitational wave detection, where stable, coherent, and mono-chromatic light is needed. The narrowness of the linewidth is determined by factors such as the laser’s gain material, resonant cavity design, and the presence of phase noise from quantum fluctuations.
Nascent surface – It is a completely uncontaminated surface, produced for example by cleavage fracture under ideal vacuum conditions.
Nash bargaining solution – It is a game theory concept which defines a unique, fair, and efficient outcome for two parties negotiating a surplus, such as dividing a resource, by maximizing the product of their utility gains over a ‘disagreement point’ (what they get if no deal is made). This solution is used in multi-agent systems and other areas of AI (artificial intelligence) to model and predict how autonomous agents can reach mutually beneficial agreements by considering their individual preferences and constraints.
Nash equilibrium – It is a stable state in a competitive system where no individual participant can improve their outcome by unilaterally changing their strategy. It is a game theory concept applied to analyze and design systems where multiple self-interested entities interact and influence each other’s decisions.
National measurement standard – It is a standard recognized by a national decision to serve, in a country, as the basis for assigning values to other standards of the quantity concerned.
National Park – It is a nature park which has been designated for conservation purposes because of unparalleled national natural, historic, or cultural significance. It is an area of natural, semi-natural, or developed land which is protected by the government.
National pipe thread (NPT) – It is a standardized thread size used in different conveyor system components. Routine checks are imperative to validate proper connections and avert potential leaks in threaded components.
National reference standard – It is a standard maintained by national laboratories, and which are the legal standards of their respective countries.
National standards – These are the standards which are established bench-marks or guidelines, normally developed by a national body. These standards define levels of quality, performance, or achievement expected across a specific field or sector. These standards aim to ensure consistency and comparability, whether in education, manufacturing, or other areas, by providing a common reference point.
Native metal – It is a deposit in the earth’s crust consisting of a metal which is occurring in nature in pure form, uncombined with other elements.
Natural aggregate – It refers to granular materials like sand, gravel, and crushed stone, sourced from natural geological deposits (riverbeds, quarries) and used in construction for concrete, roads, and other structures. They are distinguished from manufactured aggregates (like expanded shale) and recycled aggregates (like crushed concrete) and are classified by size into fine (less than 5 millimeters) and coarse (higher than 5 millimeters) particles.
Natural aging – It is spontaneous aging of a super-saturated solid solution at room temperature. It is the process which can alter the hardness and strength in some alloys after a period of time at ambient (room) temperature. It is caused by the spontaneous precipitation of constituents from a super-saturated solid solution. Normally, it increases mechanical properties but can also, in some circumstances, cause loss of properties by over-ageing.
Natural boundary condition – It specifies the value of a variable’s derivative at the boundary of a system, frequently representing physical quantities like flux or surface load, and typically arises from the variational formulation or weak form of a differential equation, such as in the Finite Element Method (FEM). Unlike essential boundary conditions, which directly prescribe the variable’s value, natural boundary conditions are implicitly satisfied when the integral formulation of the problem is derived, meaning no external constraint is imposed by the solver to enforce them.
Natural circulation – It is defined as the flow of fluid in a closed circuit driven by density differences between the heated lower part and cooled upper part of the circuit, which can lead to equilibrium among parameters such as power generated and mass flow. This phenomenon is normally utilized in heat transfer technology, particularly in conventional heat exchangers and nuclear power plant systems.
Natural circulation boiler – This is the boiler in which motion of the working fluid in the evaporator is caused by thermo-siphon effect on heating the tubes. In the natural circulation boilers, circulation of water depends on the difference between the density of a descending body of relatively cool and steam-free water and an ascending mixture of hot water and steam. The difference in density occurs since the water expands as it is heated, and hence, becomes less dense. All natural circulation boilers are drum-type boilers.
Natural convection – It is a type of heat transfer which occurs due to density differences resulting from temperature gradients, without any external forces acting on the fluid. It can be categorized into internal and external convection based on the geometry and flow patterns involved.
Natural coordinate system – It is a dimensionless, local coordinate system, typically defined for a structural element (like a finite element), where coordinate values range from -1 to +1, facilitating the derivation of element properties without direct dependence on its dimensions or global position. This system simplifies calculations in fields like finite element analysis (FEA) and atmospheric science by allowing consistent formulation of element properties, such as stiffness matrices and shape functions.
Natural diamond – It is a gemstone formed from carbon which crystallizes under extreme pressure and temperature hundreds of kilometers below the earth’s surface, making it the only gemstone composed entirely of a single element in its purest form.
Natural disaster – It is the very harmful impact on a society or community after a natural hazard event. Some examples of natural hazard events include avalanches, droughts, earthquakes, floods, heat-waves, landslides, including submarine landslides, tropical cyclones, volcanic activity and wildfires. Additional natural hazards include blizzards, dust storms, fire-storms, hails, ice storms, sinkholes, thunderstorms, tornados, and tsunamis. A natural disaster can cause loss of life or damage property. It typically causes economic damage. How bad the damage is, depends on how well people are prepared for disasters and how strong the buildings, roads, and other structures are.
Natural draft – It takes place when air or flue gases flow due to the difference in density of the hot flue gases and cooler ambient gases. The difference in density creates a pressure differential which moves the hotter flue gases into the cooler surroundings.
Natural draft burner – It is a burner which depends mainly on the natural draft created in the chimney or the venting system to induce air needed for combustion into the burner. In this type of burner, the pressure drop and combustor stack height are critical in producing enough suction to induce enough combustion air into the burners. The main significance of the natural draft type on heat transfer is that the natural-draft flames are usually longer than the forced-draft flames so that the heat flux from the flame is distributed over a longer distance and the peak temperature in the flame is frequently lower.
Natural draft cooling tower – It is a type of cooling tower which utilizes the buoyancy effect of hot and humid air to create airflow, functioning without rotating equipment such as cooling fans, making it suitable for power plants located far from coal sources. Its performance relies on the density difference between ambient air and the warmer air inside the tower.
Natural draft dry cooling tower – It is a large, chimney-like structure designed to cool hot industrial fluids, such as in power plants, by using natural convection to drive air through a heat exchanger without water evaporation. Hot air within the tower becomes less dense and rises because of then buoyancy, similar to a chimney, pulling in cooler ambient air from the base. This passive air movement cools heat exchanger finned tubes carrying the hot working fluid, making it a water-saving solution for arid regions or areas with strict water discharge regulations.
Natural ecosystem – It is a natural ecosystem is a biological environment consisting of all the organisms living in a particular area, as well as all the nonliving, physical components of the environment with which the organisms interact, such as air, soil, water and sunlight. It is all the organisms in a given area along with the nonliving (abiotic) factors with which they interact.
Natural energy – It refers to energy sourced from naturally occurring and replenishable processes or resources, encompassing both renewable sources like sunlight, wind, and hydropower, and non-renewable sources such as fossil fuels formed over geological time. The core principle is harnessing the earth’s inherent energy potential, with a growing emphasis in engineering on developing technologies to capture and utilize renewable forms of natural energy for sustainable power generation.
Natural fibres – These fibres are obtained from organic material (such as materials produced by plants). Natural fibres suffer from several problems including susceptibility to rotting, degradation, mildew, and wear out very quickly. These fibres can be used as a component of composite materials, where the orientation of fibers impacts the properties. Natural fibres can also be matted into sheets to make paper or felt. Natural fibres are good water absorbents and can be found in different textures. Cotton fibres made from the cotton plant, for example, produce fabrics which are light in weight, soft in texture, and which can be made in different sizes and colours.
Natural fibre rope – It is a rope which is made from natural fibres. Cotton, sisal, manila, coir, and papyrus are materials which can be used to create a natural rope. Natural ropes have a susceptibility to rot, degrade, and mildew. They also wear out very quickly and lose much of their strength when placed in water.
Natural fine aggregate – It is small-sized, naturally occurring filler material, very frequently river sand, with a maximum particle size of typically 5 millimeters, which is used in construction materials like concrete and mortar to fill voids, improve workability, and provide a smooth finish. It is a main (or virgin) aggregate, meaning it comes directly from a natural source rather than being a by-product of industrial processes.
Natural frequency – It is the inherent rate at which a system or object tends to vibrate when set into motion and then left to oscillate freely, without any external forces or continuous driving. This inherent property is determined by the system’s physical characteristics, such as its mass and stiffness, and is a crucial factor in understanding resonance, which occurs when an external force matches the natural frequency, leading to amplified vibrations.
Natural gas – It is an environmentally friendly non-renewable gaseous fossil fuel which is extracted from deposits in the earth. It is a clean fuel with a high efficiency. It is transported to long distances (up to 5,000 kilometers) through a pipeline network. It is normally supplied to the consumers as (i) piped natural gas (PNG), (ii) compressed natural gas (CNG), and (iii) liquefied natural gas (LNG). Piped natural gas which is supplied to the consumer with the pipeline pressure at the consumer end normally less than 1.6 mega-pascal (MPa). Compressed natural gas is a form of natural gas which undergoes compression (200 mega-pascals to 250 mega-pascals) is supplied in containers. Liquid natural gas is made by cooling natural gas to a temperature of minus 162 deg C. At this temperature, natural gas becomes a liquid and its volume is reduced by 600 times. Natural gas is a mixture of hydro-carbons consisting primarily of methane (CH4), normally in a percentage of over 85 % by volume. Other hydro-carbons in natural gas include varying amounts of various higher alkanes such as ethane, propane, and butane etc. It also contains water vapour (H2O) at varying degrees of saturation, or condensed water. It can also contain percentages of nitrogen (N2), carbon di-oxide (CO2), hydrogen sulphide (H2S), and helium (He) etc. Natural gas is an odourless, colourless, tasteless and non-toxic gas. It is lighter than air and burns with a clean blue flame when mixed with the requisite amount of air and ignited. It is considered one of the cleanest burning fuels. On burning it produces primarily heat, carbon di-oxide, and water. Quantities of NG are measured in normal cubic meters (corresponding to 0 deg C and 0.1 mega-pascal pressure) or standard cubic feet (corresponding to 16 deg C and 0.1 mega-pascal absolute pressure). The higher heat value of one cubic meter of natural gas varies from around 39.75 mega-joules to 41.85 mega-joules. Its density is around 0.85 kilograms per cubic meters.
Natural gas boiler – It is a closed vessel which burns natural gas to convert its chemical energy into thermal energy, heating a fluid (normally water) to produce hot water or steam for heating, power generation, or other processes. These systems utilize components like heat exchangers, burners, and pumps to transfer this heat and circulate the hot fluid or steam to meet industrial demands.
Natural gas combined cycle – It is a power generation system which uses both a gas turbine (Brayton cycle) and a steam turbine (Rankine cycle) to convert natural gas into electricity with high efficiency. The hot exhaust from the gas turbine, after driving its own generator, is used in a heat recovery steam generator (HRSG) to create steam, which then drives a steam turbine to generate additional electricity, considerably boosting the overall thermal efficiency and reducing emissions compared to conventional power plants.
Natural gas liquefaction – It is the process of cooling natural gas to around -162 deg C, transforming it into a liquid (liquefied natural gas, or LNG) which occupies around 1/600th of its original volume. This process, which occurs in large-scale, energy-intensive liquefaction plants, uses complex refrigeration systems like cascade or mixed-refrigerant processes to facilitate the safe, economical transport of natural gas across oceans through specially designed ships.
Natural gas pipeline – It is an engineered system of interconnected pipes used to transport natural gas from its source to end-users like refineries, distributors, or power plants, needing rdesign considerations for flow, pressure management (frequently through compressor stations), material integrity, and potential contaminants to ensure safe and efficient delivery. These complex networks include gathering, interstate / intrastate, and distribution pipelines, all designed to transport the fuel through different stages of the oil and gas value chain.
Natural gas processing – It consists of a series of steps used to separate different hydrocarbons and fluids from raw natural gas, including purification processes to remove impurities such as hydrogen sulphide and carbon di-oxide, and the extraction of natural gas liquids (NGLs) before transportation or consumption.
Natural gas reformer – It is a system which converts natural gas into valuable products, mainly hydrogen and carbon mono-oxide (synthesis gas), using high-temperature, catalytic processes like steam-methane reforming. This process involves reacting natural gas (mostly methane) with steam, or through partial oxidation, to break down the hydro-carbons into a hydrogen-rich gas mixture which is used in different industries like ammonia production, direct reduced iron production, and fuel cells. Natural gas reformer operates under specific conditions to convert natural gas into syngas, utilizing equilibrium models and reactions such as the water-gas shift and carbon mono-oxide methanation, while managing the molar ratio of steam to carbon to prevent solid carbon formation.
Natural gas reforming – It is an industrial process which converts natural gas (mainly methane) into hydrogen and carbon mono-oxide (syngas) through high-temperature reactions with steam or partial oxidation, frequently catalyzed by metal. This mature technology is the main method for hydrogen production, used to create hydrogen-rich gas.
Natural gas steam methane reforming (SMR) – It is an economic method for hydrogen generation where natural gas is dissociated into hydrogen and carbon mono-oxide using steam through a water gas reaction, followed by further conversion to hydrogen and carbon di-oxide through the water gas shift reaction.
Natural gas steam reforming – It is a well-established technology for hydrogen production which involves the thermal decomposition of methane and steam, typically at temperatures between 800 deg C and 1,000 deg C, and includes the separation of carbon di-oxide from the product gases for pure hydrogen generation.
Natural glue – It is an adhesive derived from organic, animal, or vegetable sources. These adhesives create strong bonds for materials like wood, paper, and fabric but normally have poor resistance to moisture and high temperatures, with their use mainly limited to paper, board, and lightweight wood products.
Natural gypsum – It is a soft, naturally occurring mineral composed of calcium sulphate di-hydrate (CaSO4.2H2O)), a sedimentary rock used mainly in construction for its fire resistance, humidity control, and ease of use. Mined globally, it is processed into products like plaster and drywall, serving as a set retarder in cement, a soil conditioner, and a binding agent for creating different building materials, including gypsum-reinforced composites.
Natural hazard – It is a natural disaster which is a sudden, violent, and destructive change in the environment caused by natural processes. Natural disasters can include floods, earthquakes, hurricanes, droughts, wildfires, and landslides.
Natural hematite – It is an iron ore (mainly Fe2O3) which serves as a principal source of iron and possesses chemical and physical properties making it suitable for applications such as photo-electro-chemical water splitting, chemical looping combustion, and as a semi-conductor in solar cells and batteries. Its low-cost abundance, chemical stability, and distinctive electro-catalytic properties are particularly valued in these advanced materials engineering fields.
Natural insulation material – It is an insulating substance derived from renewable, non-petrochemical biological sources, such as plant fibres, animal fibres, or cellulose, which effectively reduces heat transfer by impeding conduction, convection, and / or radiation. These materials, including wood fibre, hemp, sheep’s wool, and recycled textiles, offer sustainability benefits like lower embodied carbon and improved thermal mass compared to synthetic options.
Natural latex – It is an aqueous dispersion of poly-isoprene particles harvested from the Para rubber tree (Hevea brasiliensis), which possesses elastic and waterproof properties. It is mainly used in several applications, including manufacturing and waterproofing.
Natural lens – It is the transparent, flexible, crystalline structure in the eye, located behind the pupil, which focuses light onto the retina to allow for clear vision. Composed mainly of proteins called crystallins, it changes shape to accommodate focus on objects at varying distances.
Natural logarithm -The number that Euler’s constant (around 2.72) is raised to in order to arrive at the value in question.
Naturally bonded moulding sand – It is a sand containing sufficient bonding material as mined to be suitable for moulding purposes.
Naturally fractured rock – It refers to rock formations containing pre-existing discontinuities called fractures, which result from brittle deformation under geological stresses. These fractures are planar breaks with two rough walls, creating void spaces that form complex networks influencing fluid flow, storage, and rock mass stability in applications like underground construction and hydrocarbon reservoirs.
Naturally-occurring radio-active materials (NORM) – These are materials found naturally and are frequently found in the wastes arising from the oil, gas, and mining industries.
Naturally occurring radio-nuclides (NOR) – These are radioactive isotopes found in the environment from the earth’s formation, including primordial radio-nuclides like uranium (U-238, U-235), thorium (Th-232), and potassium (K-40), along with their decay products. These elements are present in bedrock, soil, water, and air, contributing to telluric radiation, and can become concentrated in industrial processes involving oil, gas, and mining, forming ‘naturally occurring radioactive material’ (NORM) which needs engineering control for safety.
Natural organic matter – It refers to the collection of complex, non-living organic compounds derived from the decomposition of plant and animal matter, found in different natural environments like soils, water, and sediments. It includes components such as humic substances, fulvic acids, and humic acids, which are significant for soil fertility, water quality, and can affect water treatment processes. Natural organic matter is an important part of the terrestrial carbon cycle and plays several roles in ecological systems, including influencing nutrient cycling and acting as a sorbent for contaminants.
Natural oxide – It is a metal oxide which forms spontaneously on a metal’s surface, providing protection against corrosion and environmental factors. It is also a mineral compound composed of oxygen and another element which exists naturally in the earth’s crust. These oxides are crucial for improving material properties and frequently serve as the basis for valuable mineral ores.
Natural oxide film – It is a thin layer, typically a few nano-meters thick, which forms on the surface of metals and alloys in air, resulting from the oxidation process influenced by environmental conditions and chemical reactivity. This film can affect surface interactions and tribological behaviour, with its properties varying based on the specific metal and environmental factors.
Natural oxide layer – It is a thin, self-formed layer of metal oxide which spontaneously develops on the surface of metals when they are exposed to air or other oxygen-containing environments, providing a protective barrier against further corrosion and environmental damage. These layers are frequently called ‘native oxide layers’ or ‘passive films’ and are known for their ability to slow down or even prevent further oxidation.
Natural phenomena hazard (NPH) – It is an act of nature (for example, earthquake, wind, hurricane, tornado, flood, precipitation [rain or snow], and volcanic eruption etc.), lightning strike, or extreme cold or heat) which poses a threat or danger to workers, the public, or to the environment by potential damage to structures, systems, and components.
Natural phenomena hazard (NPH) mitigation – It is an action taken to reduce the impacts of natural phenomena hazard. This includes natural phenomena hazard resistant design, evaluation, construction requirements, and operational procedures.
Natural pozzolans – These are naturally occurring siliceous or aluminous materials, frequently of volcanic origin, which are ground into a fine powder and, when combined with water and lime (or calcium hydro-oxide), form compounds which have cementitious properties and improve the strength and durability of concrete. These materials improve concrete’s resistance to chemical attacks and provide long-term strength development by reacting with the lime produced during the cement hydration process.
Natural resource management – It is the wise and sustainable planning, use, and protection of earth’s resources, such as land, water, minerals, plants, and animals, to ensure they benefit both present and future generations. It involves scientific, technical, and social knowledge to balance human needs with the long-term health and productivity of the environment, promoting sustainability for ecosystems and human livelihoods.
Natural resources – These are those resources which are drawn from nature and used with few modifications. This includes the sources of valued characteristics such as commercial and industrial use, aesthetic value, scientific interest, and cultural value. Natural resources are materials or substances found in nature which are useful or valuable to humans. They exist independently of human intervention and can be used for several purposes, including sustenance, economic activities, and general well-being.
Natural resources conservation – It is the responsible and sustainable management and protection of earth’s natural resources (like water, air, soil, plants, animals, and minerals) to ensure their continued availability for future generations while also meeting the needs of the present population. This involves using resources wisely, reducing waste and pollution, preventing environmental damage, and protecting biodiversity for the benefit of both humanity and the planet.
Natural resources exploration – It is the process of finding, assessing, and characterizing natural resources like minerals, petroleum, and other valuable materials within the earth’s crust or environment. It involves different activities, including geological mapping, geophysical surveys, geochemical analysis, and drilling, to determine the quality, quantity, location, and economic viability of a potential resource deposit.
Natural rubber – It is a good material for belt cover rubbers since it has a very good tensile strength and elongation, high heat resistance and elasticity, high shear and tearing strength, and good abrasion resistance characteristics. It is stable within the temperature range of -30 deg C to + 80 deg C. With special rubber compounding a widening of this range can be achieved from -40 deg C to + 100 deg C. Natural rubber is resistant to water, alcohol, acetone, dilute acids, and alkalis. It has limited resistance to concentrated acids and alkalis where compounding and service temperatures are major consideration. With special compounding, natural rubber-based mixes can be made antistatic and flame resistant. By adding anti-ozonants a substantial protection against harsh temperature effects, sunlight, and ambient weather conditions can be achieved.
Natural sand – It is a granular material composed of finely divided rock and mineral particles, typically less than 5 millimeters in size, formed by natural weathering processes like water and wind erosion over time. Found in diverse locations such as river-beds, sea-beds, and beaches, its composition varies based on local geology but frequently includes quartz along with other minerals and shell fragments. This includes soft sandstone where little pressure is required to separate the individual grains. Natural sand is a fundamental building material, mainly sourced from naturally occurring deposits rather than being mechanically crushed.
Natural stone – It is the rock or mineral substance which is extracted directly from the earth’s crust and used in construction and design for its durability, timeless beauty, and unique characteristics. Formed over millions of years through different geological processes, it is quarried from different locations and processed into products like tiles, countertops, and decorative features. Common examples include granite, marble, limestone, and sandstone.
Natural strain – It is the ratio of the change in dimension, resulting from a given load increment, to the magnitude of the dimension immediately prior to applying the load increment. In a body subjected to axial force, the natural logarithm of the ratio of the gauge length at the moment of observation to the original gauge length. It is also known as true strain.
Natural structure – It is a formation, configuration, or arrangement which arises from natural processes and is not a product of human intervention or construction. These structures are formed by geological, biological, or chemical forces over time and can range from macroscopic features like mountains and rivers to microscopic arrangements of molecules.
Natural uranium– This refers to the properties of naturally-occurring uranium (U) as found in natural sources. It contains 0.7 % Uranium-235, 99.3 % Uranium-238, and a trace of Uranium-234. In terms of the quantity of radioactivity, it contains around 2.2 % Uranium-235, 48.6 % Uranium-238, and 49.2 % Uranium-234.
Natural variable – it is a set of dimensionless, independent variables which define the magnitude of physical phenomena or a thermodynamic potential, allowing other quantities to be calculated through partial differentiation. In thermodynamics, these variables, e.g., temperature (T) and pressure (P) for Gibbs free energy (G), are the most convenient for describing a system’s equilibrium state and deriving its thermodynamic properties.
Natural variation – It is the inherent diversity and randomness found in physical materials, or natural systems, arising from factors like environmental differences, or inherent inconsistencies in formation and processing. In manufacturing, it refers to acceptable inconsistencies in materials or processes. In the environment, it can describe natural fluctuations in climate, such as El Nino, which deviate from a long-term average without human influence.
Natural ventilation – It is a passive building technique which provides fresh air and air circulation in a space by utilizing natural forces like wind and temperature differences (the stack effect) instead of mechanical systems. It involves air entering and exiting a building through openings such as windows and doors, which is an energy-efficient and sustainable method for improving indoor air quality and comfort.
Natural water content – It is the ratio of the mass of water to the mass of dry solids in a soil sample, normally expressed as a percentage. This value indicates how much water is in a given amount of soil and is a crucial property in geotechnical engineering and construction for understanding soil behaviour.
Natural weathering – It is the breakdown and alteration of rocks, minerals, and other materials at or near earth’s surface through physical, chemical, and biological processes, without movement of the weathered material. Caused by agents like water, ice, wind, temperature changes, and living organisms, this in-place disintegration and decomposition create smaller particles and new minerals, which is the first step in forming soil and shaping landscapes.
Natural zeolite – It is a group of microporous, crystalline aluminosilicate minerals formed by the interaction of volcanic glass with alkaline water, characterized by a three-dimensional framework of silicon and aluminum tetrahedra with open cavities and channels. These structures allow for ion exchange and adsorption, making them effective for water and pollutant removal, soil conditioning, and other industrial applications.
Nature or traceability of costs – As per nature or traceability of costs there are direct costs and indirect costs. The direct costs are the ones which can be directly assigned to each type of material or activity at the time of its occurrence, i.e., it is connected directly to each type of good or cost function. The direct costs of a process can be easily identified and quantified from necessary resources to carry out the process activities. These costs are directly attributed to the work of the process and hence do not need apportionment to be allocated to the process. Direct costs are directly attributable or traceable to cost object. The indirect cost is unable to segregate the portion pertaining to each product or different service at the time of application of the cost. Such separation is performed later by a special criterium called apportionment. This cost can be apportioned in different ways and the adequacy of the same depends on the branch to which the organization operates and its needs, so it is an analysis of the best cost allocation. Indirect costs are not directly attributable or traceable to cost object. Indirect costs are allocated or apportioned to the cost objects.
Naval brass – It is a nominal 62 % copper / 37 % zinc brass which has a 1 % tin addition to improve its corrosion resistance in marine environments.
Naval bronze – It is sometimes called naval brass. It is similar to brass but has additional qualities of resistance to saline elements. This is accomplished by changing the proportions of copper, zinc and a little tin. This alloy derived its name from its ability to survive the corroding action of salt water.
Navier–Stokes equations – These are partial differential equations which describe the motion of viscous fluid substances. These equations mathematically express momentum balance for Newtonian fluids and make use of conservation of mass. They are sometimes accompanied by an equation of state relating pressure, temperature, and density.
Navier-Stokes system – It is a set of partial differential equations (PDEs) that mathematically describe the motion of viscous fluids, such as water or air. It applies conservation laws of mass and momentum to a fluid element, incorporating viscosity (friction) to provide a realistic model of fluid behaviour. These equations are fundamental in fluid mechanics and are used to predict phenomena like weather patterns and the flow of other complex fluids.
Navigational equipment – It refers to instruments and devices used on ships to determine and maintain a correct course, including compasses, automatic pilots, and signal lights, which need regular operational tests and checks to ensure proper functioning.
Navigation equipment – It consists of instruments and devices which determine a vessel’s position, speed, and course, as well as safety features like obstacle detection and collision avoidance to ensure safe and efficient movement to a destination. Examples include traditional tools like compasses and sextants, and modern electronic systems such as radar and global positioning system (GPS).
Navy C-ring test – It is a method used to evaluate the potential for distortion in a material during heat treatment, particularly quenching. It involves using a C-shaped sample with varying thicknesses to simulate the stress and dimensional changes which can occur in a real component during heat treatment. By analyzing the distortion of the C-ring, engineers can predict and mitigate potential issues in the final product. The Navy C-ring is a specially designed sample with both thick and thin sections. This design ensures that different parts of the ring cool and transform at different rates during heat treatment, leading to internal stresses and potential distortion.
Nearby structures – These refer to existing buildings, schools, hospitals, and other facilities which can impact proposed construction projects, necessitating consideration of their proximity to avoid issues such as noise during pile driving or negative skin friction on foundation piles.
Near-dry machining – It is machining with minimum quantity lubrication (MQL). It uses a minimal quantity of oil delivered as a mist through compressed air to the cutting area, eliminating large volumes of coolant. This ‘aerosol’ format provides necessary cooling and lubrication, improving tool life and improving part quality while offering substantial cost reductions and environmental benefits compared to flood coolant systems.
Nearest integer – It is the whole number which is closest to a given real number, determined by rounding the number to the one’s place. To find it, one is to look at the digit in the tenths place, e.g., if it is 5 or higher, one is to round up, and if it is less than 5, one is to round down. For example, 4.23 rounds down to 4, while 11.5 rounds up to 12.
Near-infrared laser – It is a laser which emits light in the near-infrared spectrum, a range of electro-magnetic radiation with wave-lengths typically between 700 nanometers and 2,500 nano-meter, just outside the visible light spectrum. This type of laser is has uses such as telecommunications, and manufacturing.
Near-infrared radiation – It is the infrared radiation in the wavelength range of 0.78 micrometers to 3 micrometers (7,800 angstrom to 30,000 angstroms).
Near-isothermal forging – It is a specialized forging process where the work-piece and dies are maintained at nearly the same, high temperature throughout the deformation process. This technique helps minimize temperature variations, leading to improved metal flow, reduced stress and cracking, and the ability to produce near-net-shape components with close tolerances.
Near-net shape – It is a manufacturing technique, in which the initial production of the item is very close to the final, or net shape. This reduces the need for finishing operations (e.g., surface finishing). By minimizing the use of finishing methods like machining or grinding, near-net-shape production substantially reduces the production time and costs.
Near-net-shape forming – It is a manufacturing technique which produces parts closely matching their final geometry, needing minimal post-processing like machining, hence saving material and reducing manufacturing time and costs. This method aims to form a component to nearly the final shape in one step, as opposed to traditional processes which frequently need extensive material removal.
Near-net-shape processes – These are shape replication processes which produce parts needing little or no subsequent processing to get the finished part.
Near miss – it is an incident, which did not show a visible result, but had the potential to do so.
Near miss incident – It is an incident which physically occurred but there was no personal injury to the employee, contractor or visitor bur which could have resulted in a serious injury and needs to be followed up in the same way as a lost time injury but recorded as a near miss.
Nearly zero-energy building – It is a highly energy-efficient building with very low energy consumption, where the minimal energy needed is met to a substantial extent by renewable energy sources produced on-site or nearby. The concept aims for a balance between the energy consumed annually by the building and the renewable energy it generates over the same period.
Nearly zero-energy building standard – It refers to a set of energy performance requirements for buildings which mandates at least 30 % of annual primary energy to be covered using renewable energy sources generated on-site, applicable to both new and renovated buildings.
Neat brick – It is the brick with faces arranged so one of the flat faces in inclined toward the other, almost eliminating one end face.
Neat cement – It is the Portland cement mixed with water only.
Neat oil – It is a hydro-carbon oil with or without additive. It is used undiluted. This term is used particularly in metal cutting to distinguish these fluids from soluble oils (emulsions).
Neat resin – It is the resin to which nothing (additives, reinforcements, and so on) has been added.
Nebulizer – It is a device for converting a sample solution into a gas-liquid aerosol for atomic absorption, emission, and fluorescence analysis. This can be combined with a burner to form a nebulizer burner.
Necessary costs – It is a component of cost of quality. Necessary costs are required to achieve and sustain a defined objective or standard of work. These are those costs which are needed to carry out an activity efficiently and to achieve and sustain a defined standard of work. These costs are required to be incurred. Any action to cut or reduce these costs has an adverse effect on the organizational performance. Necessary costs include prevention and inspection costs.
Neck – It is the contact area between abutting particles in compact undergoing sintering.
Neck down – It is a thin core or tile used to restrict the riser neck, making it easier to break or cut off the riser from the casting.
Neck-down core – It is a specialized core used to create a constricted ‘neck’ or connection point between a casting and its riser. This design improves the efficiency of the casting process and considerably reduces the labour rneeded for post-casting finishing.
Neck formation – It is the growth of inter-particle contacts through diffusion processes during sintering.
Necking – It is the process by which a material in tension reduces locally its cross-sectional area. It is -important in creating imperfections and voids in metal deformation processes. A high strain-rate sensitivity in the material means which an incipient neck becomes stronger and spreads the deformation to neighbouring material, thereby resisting neck formation. It is also the reduction of the cross-sectional area of a material in a localized area by uniaxial tension or by stretching. It is also the reduction of the diameter of a portion of the length of a cylindrical shell or tube.
Necking down – It is the localized reduction in area of a sample during tensile deformation.
Necking instability – It is defined with the aid of true stress and true strain, which differ from definitions of engineering stress and strain.
Necking region – It is an unstable, localized area in a material undergoing tensile stress where the material’s cross-sectional area decreases considerably, leading to a concentration of strain and eventually fracture. This phenomenon occurs after the material’s ultimate tensile strength (UTS) and marks the transition from uniform to localized deformation, forming a ‘neck’ from which the material ultimately breaks.
Necking zone – It is the highly unstable, localized area in a material under tensile stress where the cross-sectional area decreases dramatically, leading to eventual fracture. This phenomenon begins after a material reaches its ultimate tensile strength and continues as deformation concentrates, with the strain in the surrounding area decreasing while strain within the neck region intensifies until the material breaks.
Necklace structure – It is a type of structure formed because of the nucleation of new grains at grain boundaries. This happens with increasing strain beyond the critical condition for the onset of a new softening process of dynamic recrystallization this value.
Needed competencies – These refer to the combination of knowledge, skills, and attitudes which individuals are required to possess to fulfill specific job roles and responsibilities effectively, particularly in relation to organizational goals and training needs. These competencies are necessary for navigating complex tasks and challenges in different sectors, including engineering.
Needle bearing – It is a bearing in which the relatively moving parts are separated by long, thin rollers which have a length-to-diameter ratio exceeding 5 (five).
Needled mat – It is a mat formed of strands cut to a short length, then felted together in a needle loom with or without a carrier.
Needle roller – It is a very slender, cylindrical rolling element characterized by a diameter of 6 millimeters or less and a length-to-diameter ratio higher than 3:1. They are used in needle roller bearings, which are rolling-element bearings designed to handle high radial loads and maintain high rigidity within a restricted radial space, making them suitable for applications with limited room, such as automotive transmissions and compressors.
Needle roller bearing – It is a type of roller bearing which uses small-diameter, long rollers as its rolling elements, which are called needle rollers. Because of the needle rollers’ small diameter, the bearing has a low cross-sectional height, allowing it to handle high radial loads and provide high rigidity within a restricted radial space.
Needles – These are elongated or rodlike particles with a high aspect ratio.
Needle valve – It is a type of small valve which is used for flow metering having a tapered needle-point plug or closure element and a seat having a small orifice. Needle valves are used to make relatively fine adjustments in the amount of fluid flow. The distinguishing characteristic of a needle valve is the long, tapered, needle like point on the end of the valve stem. This ‘needle’ acts as a disk. The longer part of the needle is smaller than the orifice in the valve seat and passes through the orifice before the needle seats. This arrangement permits a very gradual increase or decrease in the size of the opening. Needle valves are frequently used as component parts of other, more complicated valves. For example, they are used in some types of reducing valves.
Needling agents – These are special agents such a boron which markedly increase the hardness of steel.
Needs assessment – It is a systematic process to identify the gaps between a current situation and a desired future state for a project, system, or organization. It involves gathering and analyzing information to understand what is needed to achieve goals, hence providing a foundation for planning, designing, and justifying engineering projects by establishing clear objectives and available resources.
Neel temperature, Neel point – It is the critical temperature at which an anti-ferro-magnetic material loses its ordered magnetic structure and becomes paramagnetic. Below the Neel temperature, the material’s magnetic moments are aligned in an antiparallel, ordered fashion. Above this temperature, the thermal energy overcomes these opposing forces, and the magnetic moments become randomly oriented, behaving like a paramagnet. It is the temperature below which spins in an anti-ferro-magnetic material are ordered anti-parallel so that there is zero net magnetic moment.
Negative affect – It refers to the experience of emotional distress and unpleasant feelings such as anxiety, sadness, anger, fear, and guilt. It is a general dimension of subjective distress which includes several aversive mood states and can influence attitudes and behaviours, sometimes leading to more negative interactions or interpretations of events.
Negative binomial regression – it is similar to Poisson regression except that there is no restriction that the mean and variance of the study end point are to be identical.
Negative camber – It is a profile on the roll faces where the diameter is smaller in the middle and increases toward the ends. This ‘hour-glass’ or concave shape is ground into the rolls to compensate for the bending which occurs under the massive pressure of the rolling process. Negative camber is also a defect on plate and strip. It occurs when the rolled metal strip or plate curves laterally to one side along its length. The term is a reference to its appearance when viewed from above, resembling the inward tilt of a car’s wheels with negative camber. This defect occurs when one side of the metal is elongated more than the other during the rolling process, causing the material to bend toward the side with the shorter length. It is a critical quality issue in rolling mills, as excessive camber can cause serious problems in later processing stages.
Negative consequence – It is an unwelcome outcome which reduces the likelihood of a behaviour, action, or process reoccurring, frequently resulting in undesirable social, economic, or environmental impacts. These adverse effects can include things like losing privileges, experiencing economic hardship, or causing environmental harm. Negative consequences are unintentional adverse effects of processes on their surroundings, which can include issues such as sound pollution or detrimental impacts on the community despite the efficiency of the process.
Negative corona – It is a phenomenon in which negative ions are generated by electron attachment to oxygen atoms in a high electric field, resulting in an intense corona discharge which charges particles with the same negative polarity.
Negative corona discharge – It is a luminous phenomenon in a high electric field near a negatively charged (cathodic) conductor where electrons are repelled outward, forming a bright, filamentary glow which ionizes surrounding air and generates radicals and negative ions. This discharge occurs when positive ions accelerate toward the cathode, causing electron emission, which then accelerates outward to create high-energy electrons known as streamers that ionize the gas, forming a plasma that results in a visible light.
Negative crowned pulley – It is a pulley with a crown which is used to pull tail pulleys or assist in belt tracking. This design includes raised areas set equally in from each end and is applied to tail pulleys which are 600 millimeters. Over all width and wider, contributing to effective belt tracking.
Negative damping – It refers to a condition where the amplitudes of vibrations magnify and increase over successive cycles, leading to destabilization of a system or object. This phenomenon occurs when the natural frequency of the system coincides with the frequency of external ground movement, making it highly vulnerable to failure.
Negative distortion – It is the distortion in the image which occurs when the magnification in the centre of the field exceeds that in the edge of the field. It is also termed barrel distortion.
Negative electrode – It is the cathode in an electrolytic cell (where external power is applied) and the anode in a galvanic cell (like a battery, where a spontaneous reaction occurs). It is the electrode where a species gains electrons, a process called reduction, and where oxidation happens, releasing electrons to the electrode itself.
Negative error – It occurs when a measured quantity is less than the actual or true value. This results in a negative percent error when calculated as [(experimental value – true value) / true value] x 100 %. In measurement contexts like surveying, negative error arises from tools which are longer than their standard length.
Negative eye-piece – It is an eye-piece in which the real image of the object forms between the lens elements of the eye-piece.
Negative feedback It is the feedback from a control system output which tends to oppose the input.
Negative frequency – It is a mathematical concept in signal processing and complex analysis which represents a phase shift or a different direction of rotation for a rotating complex exponential, rather than a negative rate of oscillation. While positive frequencies correspond to counter-clockwise or increasing phase rotation, negative frequencies correspond to clockwise or decreasing phase rotation. In the Fourier spectrum of a real-valued signal, negative frequencies appear symmetrically around zero and, when combined with their positive counterparts, result in a real-valued signal.
Negative gradient – It indicates a downward slope on a graph, meaning that as the input (e.g., x-axis) increases, the output (e.g., y-axis) decreases. A negative gradient also points in the direction of a function’s most rapid decrease or the path of steepest descent, as seen in the gradient descent algorithm used to find a function’s minimum.
Negative integer – It is a whole number with a value less than zero, represented by a minus sign preceding the number. These are the natural numbers (1, 2, 3, …) with a negative sign attached, such as -1, -2, -3, and so on. On a number line, negative integers are located to the left of zero.
Negatively charged surface – It is a surface with an excess of electrons, giving it a net negative electrical charge. This excess of electrons results in a negative surface charge density, a measure of charge per unit area on the surface. These surfaces can attract positively charged particles (cations) and repel negatively charged particles (anions) because of the electrostatic forces.
Negative mean stress – In fatigue analysis, it refers to a situation where the average stress within a cyclic load is compressive, meaning the material is experiencing a pushing force on average rather than a pulling force. This contrasts with positive mean stress, where the average stress is tensile, and zero mean stress, where the average stress is zero.
Negative net income – It is also known as a net loss. It occurs when the organizational total expenses exceed its total revenue for a specific period. In simpler terms, it means the organization has lost money rather than made a profit during that time. This situation is indicated by a negative number on the organization’s income statement.
Negative number – It is a real number with a value less than zero, represented by a minus sign (-) before the number. These numbers are located to the left of zero on a number line and are used to represent quantities such as debts, losses, or temperatures below freezing. Examples of negative numbers include -3, -5.2, and -1/2.
Negative operating income – It is also known as an operating loss. It occurs when the organization’s total operating expenses exceed its total revenue from its core organizational activities. In simpler terms, the organization is losing money from its primary operations.
Negative plate – It is an electrode in an electrical cell, such as a battery, that has a lower electrical potential and serves as the cathode, collecting electrons during a discharging cycle. In lead-acid batteries, the negative plate is made of porous metallic lead and serves as a current collector during discharge.
Negative pole – It is an atom with high electro-negativity, where electrons are attracted within a solvent molecule, resulting in a molecule with a permanently uneven distribution of electrostatic charge.
Negative pressure – It means a pressure which is less than the surrounding atmospheric pressure, causing air or other substances to flow into the area of lower pressure. It is a relative concept, not a physical state of being less than zero pressure, and is used in several applications.
Negative quenching – It is also called negative hardening. It is the accelerated cooling in water or oil, from a temperature below the critical range.
Negative replica – It is a method of reproducing a surface got by the direct contact of the replicating material with the sample. Using this technique, the contour of the replica surface is reversed with respect to that of the original.
Negative resistance – It is a voltage / current characteristic where increasing current leads to decreased voltage drop across the device.
Negative risk – It is also known as a threat. It is an uncertain event or condition which has the potential to adversely affect project objectives, such as causing budget overruns, schedule delays, technical failures, or resource shortages. These risks represent potential negative outcomes that, if they occur, can hinder or even cause the failure of a project. Project managements manage negative risks by applying strategies like avoidance, mitigation, transfer, and acceptance.
Negative thermoie heat exchange – In shell moulding, it is improving the mass-surface ratio by simulating profile geometry of pattern or core cavity on the underside. It boosts running temperature of high projections by 25 %.
Negative temperature coefficient (NTC) of resistance – A negative temperature coefficient refers to materials which experience a decrease in electrical resistance when their temperature is raised. Materials which have useful engineering applications normally show a relatively rapid decrease with temperature, i.e., a lower coefficient. The lower the coefficient, the higher a decrease in electrical resistance for a given temperature increase. Negative temperature coefficient materials are used to create inrush current limiters (since they present higher initial resistance until the current limiter reaches quiescent temperature), temperature sensors, and thermistors.
Negative temperature coefficient (NTC) of resistance of a semi-conductor – An increase in the temperature of a semiconducting material results in an increase in charge-carrier concentration. This results in a higher number of charge carriers available for recombination, increasing the conductivity of the semi-conductor. The increasing conductivity causes the resistivity of the semi-conductor material to decrease with the rise in temperature, resulting in a negative temperature coefficient of resistance.
Negative traits – These refer to undesirable characteristics or failures in design or fabrication processes, which are frequently underreported in engineering contexts, leading to a lack of understanding and learning from these failures. Negative trait is also a personality characteristic, behaviour, or quality which is considered undesirable, harmful, or detrimental to oneself or others. These traits can negatively impact relationships, social interactions, decision-making, and overall quality of life. Examples of negative traits include dishonesty, arrogance, selfishness, laziness, and impatience.
Negligible effect – It means something has so little impact or importance that it can be ignored or is not worth considering. The term describes a quantity or degree which is so small and insignificant that it does not affect the final outcome or deserves any attention.
Negligible velocity – It refers to a very low velocity which is considered insignificant to the point where it does not significantly affect the outcome of calculations or the overall energy balance in a physical system, allowing for simplifications in engineering and physics problems. For example, when analyzing a nozzle, if the inlet fluid velocity is negligible, it can be treated as zero in the energy equation, simplifying the calculation of the exit velocity.
Negator spring – It is a thin metal band slightly concave in cross-section. When coiled it adopts a flat cross-section but when unrolled it returns to its former curve, hence producing a constant force throughout the displacement and negating any tendency to re-wind. The most common application is the retracting steel tape rule.
Negligence – It is the omission to do something, which a reasonable person, guided upon those considerations which ordinarily regulate the conduct of human affairs do, or something, which a prudent and reasonable person does not do.
Negentropy – It is the concept of ‘negative entropy’, which refers to a system’s ability to create and maintain order in contrast to the natural tendency toward disorder (entropy). It represents a measure of the order, organization, and complexity within a system, achieved by exporting its disorder to the environment. Examples include living organisms, which use energy to maintain their complex structures, or star systems, which represent organized structures against the background of space.
Negotiation – It is normally done so as to reach agreement without causing future barriers to communications. Negotiation takes place when two or more people / parties, with differing views, come together to attempt to reach agreement on an issue. It is persuasive communication or bargaining. It is a cooperative process whereby participants try to find a solution which meets the legitimate interests of the negotiating parties. It is the process between two or more parties to settle differences. In the process of negotiation parties try to reach compromise or agreement while avoiding argument and dispute. In case of any disagreement, parties understandably aim to achieve the best possible outcome for their position (or perhaps an organization they represent). However, the principles of fairness, seeking mutual benefit and maintaining a relationship are the keys to a successful outcome. It is the process of communicating back and forth, for the purpose of reaching a joint agreement about differing needs or ideas. It is a collection of behaviours that involves negotiation skills, communication, sales, marketing, psychology, sociology, assertiveness and conflict resolution. A method of negotiation is normally judged by three criteria namely (i) it is to produce wise agreement if agreement is possible, (ii) it is to be efficient, and (iii) it is to improve or at least not damage the relationship between the parties. Negotiations are viewed hard where the participants are adversaries, the goal is victory, there is application of pressure, there is distrust between participants, and there is demand of concessions as a condition of the relationship. Negotiation is considered soft when the participants are friends, goal is agreement, concessions are made to cultivate the relationship, there is trust in each other, and there is no imposement of the viewpoint of one of the parties.
Negotiation process – It is a structured dialogue involving multiple stages consisting of preparation, opening, clarification, bargaining, and closure, to reach a mutually beneficial agreement by exchanging information and making compromises. Key elements include defining objectives, understanding the other party’s needs, establishing communication ground rules, presenting and justifying positions, making concessions through give-and-take, and finally, formalizing and implementing the agreed-upon terms.
NEMA standards – These standards are voluntary standards of the National Electric Manufacturers Association (NEMA) and represent general practice in the industry. They define a product, process, or procedure with reference to nomenclature composition, construction, dimensions, tolerances, operating characteristics, performance, quality, rating, and testing. National Electric Manufacturers Association has standardized frame-size motor dimensions, including bolt-hole sizes, mounting-base dimensions, shaft height, shaft diameter, and shaft length.
Neodymium (Nd) – It is a chemical element, having atomic number 60. It is the fourth member of the lanthanide series and is considered to be one of the rare-earth metals. It is a hard, slightly malleable, silvery metal that quickly tarnishes in air and moisture.
Neodymium-doped yttrium aluminum garnet (Nd:YAG, Nd:Y3Al5O12) – It is a crystal which is used as a lasing medium for solid-state lasers. The dopant, neodymium in the +3 oxidation state, Nd(III), typically replaces a small fraction (1 %) of the yttrium ions in the host crystal structure of the yttrium aluminum garnet (YAG), since the two ions are of similar size. It is the neodymium ion which provides the lasing activity in the crystal, in the same fashion as red chromium ion in ruby lasers.
Neodymium-doped yttrium aluminum garnet (Nd:YAG) laser – It is a type of solid-state laser which uses a crystal of yttrium aluminum garnet (YAG) doped with neodymium (Nd) ions as its gain medium. This laser emits infrared light at a wavelength of 1064 nano-meters and is widely used in several applications because of its properties of deep penetration and minimal damage to surrounding areas. The core of the Nd:YAG laser is the yttrium aluminum garnet crystal, which is doped with neodymium ions (Nd3+). These neodymium ions are responsible for the laser’s ability to amplify light.
Neon (Ne) – It is a chemical element having atomic number 10. It is the second noble gas in the periodic table. It is a colourless, odourless, inert monatomic gas under standard conditions, with approximately two-thirds the density of air. The discovery of neon has been marked by the distinctive bright red emission spectrum it has shown, leading to its immediate recognition as a new element. Neon is a chemically inert gas. Although neon compounds do exist, they are mainly ionic molecules or fragile molecules held together by van der Waals forces.
Neon sign – Strictly, it is a sign which glows orange because of a discharge through neon gas. Less pedantically, it is gas discharge tube formed into a sign.
Neon-sign transformer – It is a high-voltage transformer with features intended to support operation of a neon sign.
Neo-pentyl glycol – It is an organic chemical compound. It is used in the synthesis of polyesters, paints, lubricants, and plasticizers. When used in the manufacture of polyesters, it improves the stability of the product towards heat, light, and water. By esterification reaction with fatty or carbolytic acids, synthetic lubricating esters with reduced potential for oxidation or hydrolysis, compared natural easters, can be produced.
Neoprene – It is also known as poly-chloroprene. It is a family of synthetic rubbers which are produced by polymerization of chloroprene. Neoprene shows good chemical stability and maintains flexibility over a wide temperature range. Neoprene is used either as solid rubber or in latex form and is used in a wide variety of commercial applications, such as laptop sleeves, electrical insulation, gloves, liquid and sheet-applied elastomeric membranes or flashings, and automotive fan belts.
Nernst equation – It is an equation which expresses the exact electro-motive force of a cell in terms of the activities of products and reactants of the cell.
Nernst diffusion layer, Nernst thickness – It is the diffusion layer or the hypothetical thickness of this layer as given by the theory of Nernst. It is a fictitious layer which shows the concentration profile along the direction perpendicular to an electrode surface. The thickness ‘d’ of this layer is called the effective (or equivalent) thickness of the diffusion layer. It is the thickness which the diffusion layer has if the concentration profile is a straight-line coinciding with the tangent to the true concentration profile at the interface, and that straight line is extended up to the point where the bulk concentration is reached. ‘d’ has a formal significance only. It is simply another way of writing the mass transfer coefficient ‘kd’ defined in terms of a resistivity instead of a conductivity.
Nesh – It means hot short. It is a British term applied to metal which is weak and ruptures easily under not working conditions.
Nesosilicate – It is also called island silicate. It is a silicate mineral where isolated SiO4 tetrahedra are not linked to other tetrahedra but are bonded by interstitial cations such as magnesium or iron. Because the tetrahedra are completely isolated, they are frequently referred to as ‘islands’ of silica, and the resulting structures are typically dense and equidimensional. Common nesosilicates include the olivine and garnet groups, as well as single minerals like zircon, andalusite, and kyanite.
Nesting – It is a condition found when surface finishing or machine assembling small parts where they cluster together, making them difficult to treat as individual parts. It is also orientation of sheet metal parts so as to minimize waste when cut from a large sheet. In reinforced plastics, it consists of the placing of plies of fabric so that the yarns of one ply lie in the valleys between the yarns of the adjacent ply (nested cloth).
Net annual cost (NAC) – It is the actual annual expense of a project or operation after all revenues, grants, discounts, and tax credits are accounted for. It represents the true financial burden on the organization or individual each year, providing a clearer picture than just listing total costs by removing the benefits and subsidies which reduce out-of-pocket expenses.
Net calorific value (NCV) – It is also known as the lower heating value (LHV). It is the quantity of heat released from the complete combustion of a fuel, excluding the latent heat of vapourization of the water produced during combustion and already present in the fuel. This value provides a more practical measurement of available heat since it assumes the water vapour escapes with the exhaust gases and does not contribute to usable heat.
Net charge density – It describes the quantity of total net electric charge contained within a specific volume, area, or length. It quantifies how concentrated electric charge is in a given space and is used to determine the electrostatic forces and fields generated by the distribution of charge.
Net force – It is the overall, combined effect of all forces acting on an object, essentially a single force which produces the same motion. It is a vector quantity, meaning it has both magnitude (size) and direction. To find the net force, a person is to add all the individual forces acting on an object as vectors, where forces in opposite directions cancel each other out.
Net generation – It is the quantity of electricity which a power plant produces and sends to the power grid after subtracting the electricity the plant uses to run its own equipment and systems. This includes electricity for operating generators, pumps, pollution control devices, and fuel handling systems. Basically, it is the electricity available for consumers, not the total electricity generated.
Net income – It is obtained after deducting from the net sales (i) the cost of goods sold, (ii) operating expenses, (iii) expenses on interest and depreciation, and (iv) taxes to be paid. It is also called net profit.
Net lift – It is the net vertical distance through which material is conveyed against gravity by a conveyor system. Periodic assessments are necessary to ensure efficient material movement.
Net loss – It occurs when the organization’s total expenses exceed its total revenues in a specific period, resulting in a negative income or loss. It signifies that the organization has not generated enough income to cover its costs during that time.
Net metering – It is a metering plan which allows grid customers with their own generation to be billed only for their net import of energy from the grid.
Net positive suction head (NPSH) – It is a consideration in selecting different types of the pumps In positive displacement pumps, net positive suction head varies as a function of flow determined by the speed. Net positive suction head gets reduced in the positive displacement pump with the reduction of the speed. In a centrifugal pump, net positive suction head varies as function of flow determined by the pressure.
Net present value (NPV) – It is also called net present worth (NPW). It is a way of measuring the value of an asset which has cashflow by adding up the present value of all the future cash flows that asset is going to generate. The present value of a cash flow depends on the interval of time between now and the cash flow because of the time value of money (which includes the annual effective discount rate). It provides a method for evaluating and comparing capital projects or financial products with cash flows spread over time.
Net pressure – It is a concept which describes a pressure imbalance, representing the driving force or excess pressure that causes an effect, such as the opening and growth of a fracture. It is the difference between two opposing pressures, or stresses, within a system, where the higher pressure overcomes the lower one.
Net profit – It is the financial gain of the organization after all expenses, including operating costs, interest, and taxes, have been deducted from total revenue. It is also known as the ‘bottom line’. It represents the true earnings of the organization for a specific period, indicating its financial health and ability to reinvest or distribute profits.
Net resin content prepreg – It is a prepreg product form which contains the final desired resin content and does not need resin bleeding (removal) during the cure process.
Net sales – It is a final value of sales which the organization has made after the deduction of allowances (such as damaged goods), returns and discounts.
Net shape – It is the shape of a powder metallurgy part, casting, or forging which conforms closely to the specified dimensions. Such a part needs no secondary machining or finishing. A near-net shape part can be either one in which some but not all of the surfaces are net or one in which the surfaces require only minimal machining or finishing.
Net surface – It is a surface in a manufactured part which needs no finishing in a subsequent operation.
Netting analysis – It is the analysis of filament- wound structures which assumes the stresses induced in the structure are carried entirely by the filaments, and the strength of the resin is neglected, and assumes also that the filaments possess no bending or shearing stiffness and carry only the axial tensile loads.
Network – It is a system implemented with a collection of interconnected components. Such components can include routers, hubs, cabling, telecommunications controllers, key distribution centres, and technical control devices. In power transmission, network is a system of high-voltage transmission lines, substations, and transformers which transport large quantities of electrical energy over long distances from power plants to local distribution networks, forming the backbone of the electrical grid and ensuring reliable power delivery. This high-voltage infrastructure is distinct from the lower-voltage power distribution network which delivers electricity to end consumers.
Network access – It refers to an access network, the physical infrastructure connecting end-users to a wider network like the internet, or network access control (NAC), the security system which governs who and what can connect to a network, ensuring authorized use and protecting resources. Both are critical for enabling communication and maintaining security in tele-communications and information technology (IT) systems.
Network access control (NAC) – It is a security solution which implements policies to control access to a network by verifying the identity and compliance of users and devices before granting access to network resources. Network access control acts as a network security gatekeeper, ensuring only authenticated, authorized, and compliant entities can connect to the network, hence preventing unauthorized access and bolstering the overall security of the information system.
Network analyzer – It is an analog computer system for modelling power grids. It is now displaced by digital computers.
Network availability – It refers to the percentage of time a computer network is functional and accessible to users for communication and data transfer, essentially measuring its uptime. It is a crucial indicator of a network’s reliability, with organizations frequently striving for a high standard known as ’five nines’ (99.999 % uptime) to avoid operation disruptions and costs. Availability is calculated by dividing the time the network is operational (uptime) by the total time period, and it impacts everything from organizational operations to individual ability to access online services.
Network cable – It is the cables intended for use in data inter-connections, with defined performance parameters.
Network capacity – It is the maximum quantity of electrical power a transmission line or system can deliver to meet demand, limited by factors like conductor size, voltage, and line design. It is typically measured in kilowatts (kW) and is important for ensuring the network’s stability and preventing outages by reliably supplying electricity without exceeding equipment limits.
Network circuit – It is a complex inter-connection of different elements and devices, forming a path or paths to transmit energy or data, ranging from an electrical network of components to a communication network for voice and data transmission. Unlike a simple circuit which can have a single closed path, a network circuit is frequently more complex, potentially containing both series and parallel configurations within a larger structure.
Network components – These are the hardware, software, and media which form a network’s infrastructure, enabling communication and data flow between connected devices. Key hardware examples include servers and clients (endpoints), routers and switches for directing data, and cables or wireless signals for transmission. Software components include protocols and the operating system, while transmission media refers to the physical channels for data.
Network connectivity – It is the ability of devices, systems, and applications to establish communication links and exchange data with each other. It is the fundamental process which allows a computer to access the internet, the smartphone to send messages, and organizations to operate globally. This connection can be established using different physical (like cables) or wireless (like radio waves) technologies and relies on specific protocols for data transfer.
Network data processing – It is the execution of data processing tasks within a network, where raw data is converted into a more useful format, such as comprehensible information, which can be used to make decisions. This is done using multiple inter-connected systems, potentially in different geographical locations, to handle massive volumes of data.
Network domain – It is a centralized, authoritative group of interconnected computers and devices within an IT (information technology) infrastructure which shares a common security policy, user directory, and management system. It provides structure and scalability for a network by allowing administrators to manage users, security, and resources like printers and servers from a single point of control.
Network element – It is a fundamental component within a telecommunications or computer network, encompassing any piece of equipment, device, or functionality which supports the transfer of information, such as routers, switches, servers, and even logical functions like subscriber databases. These elements are managed and interconnected to form a complete infrastructure, enabling services and the efficient routing and management of data.
Network etching – It is the formation of networks, especially in mild steels, after etching in nitric acid. These networks relate to sub-grain boundaries.
Network heat transfer – It is a simplified mathematical model of thermal systems, representing complex structures as interconnected nodes or heat exchange spaces, each with specific thermal properties. These models allow engineers to analyze and predict heat flow through a system using principles like conduction, convection, and radiation, often by translating these physical processes into analogous electrical resistance networks to understand thermal resistance and heat dissipation.
Networking equipment – It is also called network hardware. It consists of the physical electronic devices necessary for communication and data transmission between devices on a computer network. These devices include routers, gateways, switches, hubs, and modems, each with specific functions to manage, direct, and process network traffic, forming the physical infrastructure of any network. Networking equipment facilitates data communication within a network, classified according to their functionality within the Open Systems Interconnection (OSI) reference model.
Network outage – It is a period when network communication or service is unexpectedly disrupted or completely unavailable, preventing devices from connecting to each other or to online resources. These disruptions can range from a localized issue affecting a single device to a widespread problem impacting an entire region or global services. Outages are frequently caused by factors like hardware or software failures, power issues, human error, or cyber-attacks, leading to lost productivity, halted operations, and potential damage to reputation.
Network power supply – It is a system which distributes electrical power to different components of a device or system by converting the input power source into the correct voltage and current for each component. It acts as an interface, processing raw power from sources like the alternating current mains or a battery and delivering stable, regulated power to internal circuits through connectors and terminls.
Network protector – It is a type of circuit breaker used to isolate a fault from a multi-transformer supply network.
Network structure – It is a structure in which one constituent occurs mainly at the grain boundaries, hence enveloping the grains of the other constituent(s). It is a desirable feature in cemented carbide, since in the system cobalt / tungsten carbide, where the cobalt phase forms a ductile network surrounding the brittle carbide grains.
Net worth – It is the difference between total assets and total liabilities.
Net zero carbon di-oxide emissions – It means that the amount of carbon dioxide released into the atmosphere is balanced by an equal amount which is removed. This can be achieved by reducing emissions and removing carbon from the atmosphere.
Net zero emissions – It refers to achieving an overall balance between greenhouse gas emissions produced and greenhouse gas emissions taken out of the atmosphere.
Neumann band – It is as mechanical twin (deformation twin) in ferrite.
Neumann boundary condition – It specifies the value of a function’s derivative at the boundary of a domain, frequently representing a flux or normal derivative. In physical applications, this normally refers to conditions like a zero-flux or insulated boundary for heat transfer or a free surface condition in fluid dynamics. It is distinct from a Dirichlet boundary condition, which specifies the function’s actual value on the boundary.
Neural network – It is an artificial neural network, or one of the biological neural networks which the artificial networks are inspired by.
Neural network method – It is a method in artificial intelligence (AI) which teaches computers to process data in a way that is inspired by the human brain. It is a type of machine learning (ML) process, called deep learning, which uses inter-connected nodes or neurons in a layered structure that resembles the human brain.
Neural network system – It is an information processing technique which consists of interconnected processing units, or ‘neurons’, which learn by example to resolve problems. It utilizes input, activation, and output functions to process information and is configured for specific applications through a learning process known as ‘training’.
Neutral angle – It is a camera angle where the lens is positioned at the subject’s eye level, creating a balanced and relatable perspective. It does not impose power dynamics or distort proportions, making it feel natural and direct to the viewer. This angle is frequently used to create empathy and a sense of equality between the viewer and the subject. In case of metal rolling, it determines the point of no slip during rolling.
Neutral axis – It is an axis in the cross section of a beam (a member resisting bending) or shaft along which there are no longitudinal stresses or strains.
Neutral conductor – It receives and returns alternating current to the supply during normal operation of the circuit; to limit the effects of leakage current from higher-voltage systems, the neutral conductor is frequently connected to earth ground at the point of supply. By contrast, a ground conductor is not intended to carry current for normal operation, but instead connects exposed metallic components (such as equipment enclosures or conduits enclosing wiring) to earth ground. A ground conductor only carries significant current if there is a circuit fault that would otherwise energize exposed conductive parts and present a shock hazard. In that case, circuit protection devices can detect a fault to a grounded metal enclosure and automatically de-energize the circuit, or can provide a warning of a ground fault.
Neutral filter – It is a colour filter which reduces the intensity of the transmitted illumination without affecting its hue. It is also a colour filter having identical transmission at all wavelengths throughout the spectrum. Such an ideal filter does not exist in practice.
Neutral flame – It is a gas flame in which there is no excess of either fuel or oxygen in the inner flame. Oxygen from ambient air is used to complete the combustion of carbon di-oxide and hydrogen produced in the inner flame. It is also an oxy-fuel gas flame in which the portion used is neither oxidizing nor reducing.
Neutral fraction – It refers to the proportion of ions that remain neutral after scattering from a surface, as indicated by their behaviour in relation to parallel velocity.
Neutral impedance – It is a deliberately introduced resistance or reactance in the neutral conductor of an electrical system, connecting the neutral point of a transformer or generator to the earth. Its main purpose is to limit ground fault currents, controlling their magnitude and phase to prevent damage from arcing ground faults and ensure proper system protection.
Neutralization – There is a wide range of pH of the untreated wastewater and it is not so easy to treat the wastewater with such type of varying range of the pH value. To optimize the treatment efficiency the neutralization process is used to adjust the pH value. To reduce the pH value sulphuric or hydrochloric acids can be added and to raise the pH value, dehydrated lime or sodium hydroxide alkalis can be added. Normally the process of neutralization is carried in a rapid mix holding tank or in a tank used for equalization. To control the pH of the discharge in order to meet the standards, the process of neutralization can be carried out at the end of the treatment. Neutralization consists of the balancing of acidity and alkalinity by interaction. In the context of cleaning, the removal of acid soils by alkalines and alkaline soils by acids.
Neutralization number – It is an ASTM (American Society for Testing and Materials) number given to quenching oils which reflects the oil’s tendency towards oxidation and sludging. It is also known as saponification number.
Neutralization point – It determines acidity or alkalinity of oil. Acidity / acid value / acid number is milligrams of KOH (potassium hydroxide) needed to neutralize acid in 1 gram of oil. Alkalinity / base value/ base number is the milligrams of acid needed to neutralize all bases in 1 gram of oil. As the neutralization point of the oil increases, age of the oil decreases.
Neutralization reaction – It is a chemical reaction between an acid and a base which forms a salt and water. This reaction involves the combination of hydrogen ions (H+) from the acid and hydroxide ions (OH-) from the base to create water, while the remaining ions form the salt. The overall process effectively cancels out the chemical properties of both the acid and the base, leading to a neutral solution.
Neutral loading – It refers to a condition in strain hardening materials where the loading surface does not expand, and the stress remains in its plastic state without producing new plastic deformation. In this case, the mathematical expression indicates that the change in stress does not lead to loading or unloading.
Neutral oil – It is a lubricating oil obtained by distillation, which is not treated with acid or with alkali.
Neutral pH – It is 7 on the pH scale’ It is a point on the 0 to 14 scale which signifies a solution is neither acidic nor basic. This neutrality occurs when the concentration of hydrogen ions (H+) and hydroxide ions (OH-) are equal in an aqueous solution, which happens under standard conditions (25 deg C) for pure water. Solutions with a pH below 7 are acidic, and those above 7 are basic.
Neutral plane – It is a conceptual plane within a beam or cantilever. When loaded by a bending force, the beam bends so that the inner surface is in compression and the outer surface is in tension. The neutral plane is the surface within the beam between these zones, where the material of the beam is not under stress, either compression or tension. As there is no lengthwise stress force on the neutral plane, there is no strain or extension either. When the beam bends, the length of the neutral plane remains constant. Any line within the neutral plane parallel to the axis of the beam is called the deflection curve of the beam. The neutral plane is shown by the dotted line.
Neutral point – The neutral point is defined as the point on the rolled strip which has no slipping or sliding motion. It lies at the centre of the arc of contact between the strip and the rolls.
Neutral refractories – These are the refractories which are resistant to chemical attack by both acid and basic slags, refractories, or fluxes at high temperatures. Neutral refractories are chemically stable to both acids and bases and used in the areas where slag and environment are either acidic or basic. Examples are carbon graphite, chromites and alumina. Graphite is the least reactive and is extensively used in the furnaces where the process of oxidation can be controlled.
Neutral voltage – It mainly refers to neutral-to-ground voltage (NEV) or neutral displacement voltage, which is the potential difference between a system’s neutral conductor and its safety ground conductor. Ideally, this voltage should be zero, but in real-world, unbalanced electrical systems with non-linear loads or harmonics, the neutral wire develops a voltage relative to ground because of the current flowing through it.
Neutral wire – It completes an electrical circuit, providing the return path for alternating current (AC) from an appliance or device back to the power source, typically a transformer. Unlike the live wire, the neutral wire is connected to the ground (or earth) at the electrical panel, ensuring it remains at or near zero volts to balance the system and facilitate the flow of current to the load.
Neutral zone – It is a region where an output is essentially zero or inactive because of a lack of sufficient input, or where a system experiences no significant action or force, such as no net airflow, induced voltage, or physical movement resistance. The specific definition of a neutral zone varies by field, from a no-airflow level in ventilation systems to a zero-voltage region in electric motors, or a band of no output in control systems.
Neutron – It is an uncharged atomic particle found in the nuclei of atoms, which can cause fission in some atoms. Neutron is an elementary particle which has around the same mass as the proton, but no electric charge. Rest mass is 1.67495 × 10 to the power -27 kilograms. An unbound (extra-nuclear) neutron is unstable and beta-particles decays with a half-life of 10.6 min.
Neutron absorber – It is a material in which a significant number of neutrons entering combine with nuclei and are not re-emitted.
Neutron absorption – It is a process in which the collision of a neutron with a nucleus result in the absorption of the neutron into the nucleus with the emission of one or more prompt -rays. In certain cases, emission of alpha-particles, protons, or other neutrons or fission of the nucleus results. It is also known as neutron capture.
Neutron activation analysis (NAA) – It is a nuclear process used for determining the concentrations of elements in several materials. Neutron activation analysis allows discrete sampling of elements as it disregards the chemical form of a sample, and focuses solely on atomic nuclei. The method is based on neutron activation and hence needs a neutron source. The sample is bombarded with neutrons, causing its constituent elements to form radioactive isotopes. The radioactive emissions and radioactive decay paths for each element have long been studied and determined. Using this information, it is possible to study spectra of the emissions of the radioactive sample, and determine the concentrations of the various elements within it. A particular advantage of this technique is that it does not destroy the sample, and hence has been used for the analysis of works of art and historical artifacts. Neutron activation analysis can also be used to determine the activity of a radioactive sample. If neutron activation analysis is conducted directly on irradiated samples it is termed instrumental neutron activation analysis (INAA). In some cases, irradiated samples are subjected to chemical separation to remove interfering species or to concentrate the radioisotope of interest. This technique is known as radiochemical neutron activation analysis (RNAA). Neutron activation analysis can perform non-destructive analyses on solids, liquids, suspensions, slurries, and gases with no or minimal preparation.
Neutron beam – It is a focused stream of electrically neutral neutrons used in industrial applications to probe the structure and dynamics of materials. Produced in nuclear reactors or particle accelerators, these beams are valuable since neutrons can penetrate deeply into matter and interact with atomic nuclei, providing insights into atomic arrangements, molecular structures, and the properties of materials which are difficult to get with X-rays.
Neutron bombardment – It is a nuclear reaction where a nucleus is struck by a neutron, frequently causing the nucleus to become unstable and undergo fission or other nuclear reactions. Since neutrons have no electrical charge, they are not repelled by the positively charged nucleus and can easily penetrate and interact with it.
Neutron capture – It is a process in which the collision of a neutron with a nucleus, result in the absorption of the neutron into the nucleus with the emission of one or more prompt -rays. In certain cases, emission of alpha-particles, protons, or other neutrons or fission of the nucleus results. It is also known as neutron absorption.
Neutron cross-section – It is a measure of the probability which an interaction of a given kind takes place between a nucleus and an incident neutron. It is an area such that the number of interactions which occur in a sample exposed to a beam of neutrons is equal to the product of the cross-section, the number of nuclei per unit volume in the sample, the thickness of the sample, and the number of neutrons in the beam which enters the sample if their velocities are perpendicular to it. The normal unit is the barn (10 to the power of -24 square centimeter).
Neutron detector – It is a device which detects passing neutrons, for example, by observing the charged particles or gamma-rays released in nuclear reactions induced by the neutrons or by observing the recoil of charged particles caused by collisions with neutrons.
Neutron diffraction – It is the application of neutron scattering to the determination of the atomic and / or magnetic structure of a material. A sample to be examined is placed in a beam of thermal or cold neutrons to get a diffraction pattern which provides information of the structure of the material. The technique is similar to X-ray diffraction but because of their different scattering properties, neutrons and X-rays provide complementary information: X-Rays are suited for superficial analysis, strong X-rays from synchrotron radiation are suited for shallow depths or thin samples, while neutrons having high penetration depth are suited for bulk samples.
Neutron embrittlement – It is the embrittlement resulting from bombardment with neutrons. It is normally encountered in metals which have been exposed to a neutron flux in the core of the reactor. In steels, neutron embrittlement is evidenced by a rise in the ductile-to-brittle transition temperature.
Neutron emission – It is a type of radioactive decay where a nucleus ejects one or more neutrons, typically occurring in neutron-rich nuclei. This process decreases the nucleus’s mass number by one for each neutron emitted but does not change the number of protons, hence resulting in a different isotope of the same element, not a new element. Neutron emission can also result from nuclear reactions, such as fission in a nuclear reactor, where emitted neutrons can then interact with other nuclei.
Neutron energy – It is the kinetic energy of a neutron, which is a subatomic particle with no electric charge. Neutrons are classified by their energy levels, ranging from low-energy thermal neutrons (around 0.025 electron volt, eV) to high-energy fast neutrons (greater than 1 mega electron volt, MeV). This energy, frequently expressed in electron volts (eV), dictates a neutron’s interaction properties with other atomic nuclei.
Neutron fluctuations – These refer to the variations in neutron population within a nuclear reactor core, which are influenced by perturbations and are characterized by larger amplitudes in molten salt reactors compared to traditional solid fuel systems due to a smaller effective fraction of delayed neutron precursors.
Neutron flux – This term refers to the number of neutrons passing through an area over a span of time. It is a measure of the intensity of neutron radiation, which is measured in neutrons per square centimeter-second.
Neutron generator – It is a device which creates neutrons by accelerating deuterium or tritium ions into a metal hydride target, causing them to undergo fusion reactions. These compact, portable devices use linear accelerators to produce high-energy neutrons, which have several applications including subsurface analysis, security, and scientific research.
Neutronic – It refers to the calculations and analysis related to kinetic parameters and feedback reactivity coefficients in nuclear reactor design, which are necessary for ensuring safety margins during operational conditions.
Neutronic analysis – It is the method used to evaluate and predict the behaviour of neutrons in a reactor core, involving a two-step calculation scheme which includes homogenization calculations within fuel assemblies and core calculations, which consider the core-wide neutron flux distribution and the effects of fuel assembly heterogeneity. This analysis incorporates cross-section adjustment theory and emphasizes computational efficiency to improve prediction accuracy in fast reactors.
Neutron radiation – It is a form of ionizing radiation which presents as free neutrons. Typical phenomena are nuclear fission or nuclear fusion causing the release of free neutrons, which then react with nuclei of other atoms to form new nuclides—which, in turn, can trigger further neutron radiation.
Neutron radiography – It is a form of non-destructive inspection which uses a specific type of particulate radiation, called neutrons, to form a radiographic image of a test-piece. The geometric principles of shadow formation, the variation of attenuation with test-piece thickness, and several other factors which govern the exposure and processing of a neutron radiograph are similar to those for radiography using X-rays or gamma-rays.
Neutron scattering – It involves creating a beam of neutrons, passing that beam through a sample, and noting where (and possibly when) neutrons scattered from the sample hit a detector. At SNS (spallation neutron source), a particle accelerator sends protons to collide with a heavy metal target to produce the neutrons in a process known as spallation.
Neutron source – This is a general term referring to the variety of materials which emit neutrons. An example of which is a mixture of radium and beryllium, which can be inserted into a reactor to ensure a neutron flux large enough to be distinguished from background radiation on neutron detection equipment.
Neutron spectrometer – Neutron spectrometer is a scientific instrument designed to detect neutrons in different energy bands. It is used to search for and determine the abundance of hydrogen, particularly in the form of buried water ice, by measuring the neutron flux and its energy dependence. The instrument uses a neutron-absorbing detector and different scintillator types to differentiate between thermal, epithermal, and fast neutrons. The data output of the instrument is typically represented as histograms of the measured amplitudes integrated over time.
Neutron spectroscopy – It consists of determination of the energy distribution of neutrons. Scintillation detectors, proportional counters, activation foils, and proton recoil are used.
Neutron spectrum – It is the distribution by energy of neutrons impinging on a surface, which can be measured by neutron spectroscopy techniques or sometimes from knowledge of the neutron source.
Neutron stress analysis – It is a technique used to determine the internal stresses within materials, particularly in the interior of components, using neutron diffraction. It is a non-destructive method which leverages the interaction of neutrons with the crystal lattice of a material to measure strain, which is then used to calculate stress. This technique is valuable for understanding residual stresses in manufactured parts and components, which considerably impact their performance and lifespan.
Neutron transport – It is the study of the motion and interactions of neutrons within a system, such as a nuclear reactor, describing how they move, scatter, and are absorbed by atomic nuclei over space, time, and energy. This complex phenomenon is crucial for understanding nuclear processes like chain reactions and designing nuclear facilities safely and efficiently.
Neutron velocity – It is the speed at which neutrons travel, a fundamental property used to classify them as fast, thermal, or cold, based on their energy levels. It is calculated from a neutron’s kinetic energy using the formula v = square root of 2E/m, where ‘v’ is velocity, ‘E’ is kinetic energy, and ‘m’ is the neutron’s mass. Neutron velocity is a critical parameter in neutron transport, affecting interactions with matter like in nuclear reactors.
New black steel sheet clippings – This scrap is for direct charging with maximum size 2.5 meters by 0.5 meters. It is free of metal which is coated, limed, vitreous enameled, and electrical sheet containing over 0.5 % silicon.
Newman-Keuls test – It is a type of post hoc or a posteriori multiple comparison test of data which makes precise comparisons of group means after ANOVA (analysis of variance) has rejected the null hypothesis.
New scrap – It is also called prompt or industrial scrap is generated from manufacturing units which are involved in the fabricating and producing various products from steel material. Scrap is generated when steel is cut, stamped, drawn, extruded, or machined. This type of scrap is generally transported quickly back to steel plants for re-melting. The supply of new scrap is a function of industrial activity. When activity is high, more quantity of new scrap is generated. The chemical composition and physical characteristics of new scrap is well known and in principle new scrap does not need any pre-treatment process before it is re-melted, although cutting to size might be necessary. This scrap is typically clean, meaning that it is not mixed with other materials.
Newt – It is the former English unit of kinematic viscosity.
New technologies – These are innovative tools, methods, processes, and products which offer substantial improvements over existing ones, leading to improved capabilities, increased efficiency, and transformative changes in industries and society. They encompass new inventions, discoveries, and applications of science, frequently characterized by rapid evolution and a substantial impact on economic and social models.
Newton (unit) – The SI (International System of Units) unit of force, which uses the symbol ‘N’. It is defined as 1 kilogram metre per square second, the force which gives a mass of 1 kilogram an acceleration of 1 metre per second per second.
Newtonian behaviour – It describes fluids whose viscosity is constant and does not change with the applied shear rate or shear stress. This means that their flow is predictable and follows a linear relationship between shear stress and strain rate, a principle established by Isaac Newton. Common examples of fluids showing Newtonian behaviour include water, dilute suspensions, and thin mineral oils.
Newtonian flow – It describes the behaviour of Newtonian fluids, where shear stress is directly proportional to the shear rate, resulting in a constant viscosity. This constant relationship is defined by Newton’s law of viscosity, with the proportionality constant being the fluid’s viscosity. Fluids showing this behaviour, like water or silicone oil under certain conditions, show predictable and linear stress-flow characteristics, unlike non-Newtonian fluids whose viscosity changes with applied force.
Newtonian fluid – It is a fluid showing Newtonian viscosity wherein the shear stress is proportional to the rate of shear. It is a fluid in which the viscous stresses arising from its flow are at every point linearly correlated to the local strain rate, i.e., the rate of change of its deformation over time. Stresses are proportional to the rate of change of the fluid’s velocity vector.
Newton’s law of viscosity – It states that the shear stress in a fluid is directly proportional to the velocity gradient (or rate of shear strain). This means that the force needed to make two fluid layers move relative to each other is directly proportional to how quickly their velocities change with distance. The constant of proportionality is called the dynamic viscosity or coefficient of viscosity, a measure of the fluid’s internal resistance to flow.
Newtonian mechanics – It is also known as classical mechanics. It is a physics framework which describes the motion of macroscopic objects, from projectiles to planets. It’s based on Newton’s three laws of motion and the law of universal gravitation. These laws explain how forces affect the motion of objects and how gravity governs the interaction between massive bodies.
Newton’s laws of motion – These are three fundamental laws describing the relationship between an object’s motion and the forces acting on it, establishing the foundation of classical mechanics. The laws state that (i) an object remains at rest or in uniform motion unless an external force acts upon it (law of inertia), (ii) the net force on an object equals its mass multiplied by its acceleration (F=ma) and (iii) for every action, there is an equal and opposite reaction.
Newton-Raphson method – It is a numerical technique which is used to find successively better approximations to the roots (or zeroes) of a real-valued function. It is an iterative method which uses the function’s value and its derivative at a given point to refine an initial guess and converge towards a root. Essentially, it approximates the function with a tangent line at a point and uses the x-intercept of that tangent line as the next approximation.
Newton’s iteration method – It is also known as the Newton-Raphson method. It is a numerical technique used to find the roots (or zeros) of a real-valued function. It works by iteratively improving an initial guess for the root using the function’s value and its derivative at that guess. The method is widely used in various fields, including mathematics, engineering, and computer science, for solving equations and optimization problems.
Newton’s law of heat transfer – It states that the rate of heat loss of a body is proportional to the difference in temperatures between the body and its surroundings while under the effects of a breeze.
Newton’s laws of motion – These consist of are three laws of classical mechanics which describe the relationship between the motion of an object and the forces acting on it. The fist law states that a body continues in its state of rest, or in uniform motion in a straight line, unless acted upon by a force. The second law states that a body acted upon by a force moves in such a manner that the time rate of change of momentum equals the force. The third law states that if two bodies exert forces on each other, these forces are equal in magnitude and opposite in direction.
Newton’s law of universal gravitation – The law states that every particle attracts every other particle in the universe with a force which is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centres.
N-Formylmorpholine (NFM) – It is the organic compound with the formula O(C2H4)2NCHO. It is the formamide of morpholine (O(C2H4)2NH). It is a colourless compound, which is a useful high temperature solvent similar to dimethylformamide. It has been used as a formylating agent.
N-Heptane – It is a straight-chain alkane with the chemical formula C7H16. It is a colourless, flammable liquid with a petroleum-like odour which is insoluble in water but serves as a versatile solvent and a standard for measuring the octane rating of gasoline.
Nib – It is a pressed pre-heated, shaped, sintered, hot pressed, rough drilled, or finished compact. It is a generic term for a piece of cemented carbide intended for use as a wire drawing die.
Nibbling – It is the contour cutting of sheet metal by use of a rapidly reciprocating punch which makes numerous small cuts.
Nicholson hydrometer oscillation – It refers to the back-and-forth, rhythmic movement of the instrument when placed in a liquid, which happens as a result of its buoyancy and inertia, causing it to rise and fall around an equilibrium point. The oscillation occurs since the hydrometer’s equilibrium is disturbed by its initial placement, and a restoring force (buoyancy and gravity) acts to bring it back to a stable position. However, because of the inertia, the hydrometer overshoots the equilibrium and continues to move, repeating the process and causing it to oscillate until it settles at a depth corresponding to the liquid’s density.
Nichrome – It is a trademarked name for an alloy mainly composed of nickel and chromium, with additions of iron and other elements, known for its high electrical resistance, high-temperature stability, and excellent resistance to oxidation. Its properties, particularly its high electrical resistivity and ability to withstand high temperatures, make it ideal for use as a heating element in devices like industrial furnaces.
Nick – For rolled products, it is a mark / an area of broken surface which is introduced after processing. The mark normally has no relationship to the rolling direction.
Nickel (Ni) – Nickel is a metallic element with a silvery-white, shiny appearance. It is the fifth-most common element on earth and occurs extensively in the earth’s crust and core. Nickel, along with iron, is also a common element in meteorites. Nickel occurs naturally in soil and water. It is also an essential nutrient for plants. It increases strength, and improves toughness. It is ineffective in increasing the hardness. It is a ferrite former. It is normally added in quantities ranging from 1 % to 4 % in alloy steels. In some stainless steels it is sometimes as high as 20 %. It is used for strength, corrosion resistance, and toughness. It increases the strength of ferrite, and hence increasing the strength of the steel. It is used in low alloy steels to increase toughness and hardenability. Nickel also tends to help reduce distortion and cracking during the quenching phase of heat treatment.
Nickel alloy – It is a metal with nickel as the main component, intentionally mixed with other elements like chromium, iron, and molybdenum to create superior properties such as improved corrosion resistance, high-temperature strength, and specific mechanical characteristics like ductility and toughness. These engineered materials are important for demanding applications in industries like energy, and nuclear reactors where extreme conditions need reliable performance beyond that of pure nickel or basic steels.
Nickel alloy electro-plating – It is done for engineering applications and includes nickel-iron, nickel-cobalt, nickel-manganese, and zinc-nickel. Iron is a cheap metal, and solutions for plating nickel-iron alloys have been developed mainly in order to reduce the cost of the metal used to form a layer of given thickness, but they have also been developed for special magnetic purposes. Cobalt and manganese are used to increase the hardness and strength of nickel plating. Additionally, nickel-manganese alloys have improved resistance to sulphur embrittlement when heated. Alloy layers 20 micrometers to 30 micro-meters thick of nickel with around 15 % molybdenum show higher hardness and resistance to corrosion than pure nickel but at the expense of a reduction in ductility to around 1 %. Coatings of nickel-tungsten show very high resistance to corrosion, but they are believed not to be true alloys and have not been used in practice. Alloys nickel-iron, nickel-cobalt, and nickel-manganese are of practical interest.
Nickel aluminide – Nickel aluminides are intermetallic compounds composed of nickel (Ni) and aluminum (Al), possessing properties that bridge the gap between metals and ceramics. They are known for their high strength and hardness, particularly at high temperatures, and excellent oxidation and corrosion resistance. However, they can also show brittleness at room temperature. Common nickel aluminides include Ni3Al and NiAl. The term is sometimes used to refer to any nickel–aluminium alloy. These alloys are widely used because of their high strength even at high temperature, low density, corrosion resistance, and ease of production. Ni3Al is of specific interest as a precipitate in nickel-based super-alloys, where it is called the gamma prime phase. It gives these alloys high strength and creep resistance up to 0.7 to 0.8 of its melting temperature. Meanwhile, NiAl displays excellent properties such as lower density and higher melting temperature than those of Ni3Al, and good thermal conductivity and oxidation resistance. These properties make it attractive for special high-temperature applications like coatings on blades in gas turbines and jet engines. However, both these alloys have the disadvantage of being quite brittle at room temperature, with Ni3Al remaining brittle at high temperatures as well. To address this problem, has been shown that Ni3Al can be made ductile when manufactured in single-crystal form rather than in polycrystalline form.
Nickel aluminum bronze – It is a high-strength, copper-based alloy containing substantial quantities of aluminum, nickel, and iron, prized for its excellent corrosion resistance, high mechanical properties like toughness, and wear resistance. This combination makes nickel aluminum bronze suitable for demanding applications in marine environments, aerospace, and heavy machinery, where it is used for components like ship propellers, valves, and bearings exposed to seawater and extreme stress.
Nickel-based alloy steel – It is a broad category encompassing iron-based steels to which nickel is added as a main alloying element, or it refers to nickel-based alloys which have iron as a substantial component. These steels gain improved characteristics like increased strength, superior toughness, improved ductility, and improved corrosion resistance, particularly in high-nickel variants. Nickel’s addition also lowers the critical cooling rate, making heat treatment easier, and helps maintain these desirable properties at both low and high temperatures.
Nickel-based catalyst – It is a catalytic material where nickel serves as the primary active component, used to accelerate chemical reactions in several industrial and scientific applications. These catalysts are valued for their high efficiency, low cost compared to noble metals, and diverse forms, including metallic nickel, nickel oxides, supported catalysts, and porous structures like Raney nickel, facilitating reactions such as hydrogen production, petroleum refining, and synthesis of chemicals like ammonia and plastics.
Nickel-based material – It is a metal or alloy with nickel as the main component, prized for its high strength, corrosion resistance, and durability in several applications, especially at extreme temperatures. These materials encompass different categories, including nickel-based alloys with other elements like iron, chromium, and molybdenum to improve properties for applications like high-temperature turbines and chemical processing equipment, and nickel-based superalloys, which are specifically designed for severe high-temperature conditions.
Nickel-cadmium (Ni-Cd or NiCad) battery – It is a type of rechargeable battery which uses nickel oxide hydroxide and metallic cadmium as electrodes, separated by a membrane and immersed in a potassium hydroxide electrolyte. Known for their durability, ability to handle high discharge rates, and performance in extreme temperatures, nickel-cadmium batteries are common in portable electronics and power tools but have declined in use because of the toxicity of cadmium and the rise of safer, more efficient alternatives like nickel-metal hydride (NiMH) batteries.
Nickel carbonyl – It is a nickel organo-metallic compound with the formula Ni(CO)4. This colourless liquid is the principal carbonyl of nickel. It is an intermediate in the Mond process for producing very high-purity nickel and a reagent in organometallic chemistry, although the Mond Process has fallen out of common usage due to the health hazards in working with the compound. Nickel carbonyl is one of the most dangerous substances yet encountered in nickel chemistry because of its very high toxicity, compounded with high volatility and rapid skin absorption.
Nickel-composite coatings – These are a type of metallic coating composed of a nickel matrix reinforced with dispersed particles of another material, such as ceramics or other metals. These coatings are created through electro-deposition or other techniques and are designed to enhance the properties of the base material, particularly in terms of wear resistance, corrosion resistance, and mechanical strength.
Nickel deposits – These are natural accumulations of nickel-rich minerals or ores, mainly formed from magmatic processes which concentrate nickel in the earth’s crust, or through weathering of nickel-bearing rocks. These deposits are mainly categorized as sulphide deposits, frequently associated with iron and magnesium-rich ultramafic rocks, and laterite deposits, which are near-surface accumulations formed by weathering.
Nickel electro-forming – It is a metal fabrication process where a conductive object is created by depositing a thick layer of nickel onto a mandrel (a mould) using an electrolytic process. The nickel deposit is then separated from the mandrel, resulting in a free-standing nickel part with precise dimensions and intricate details mirroring the mandrel’s shape. This process is distinct from electro-plating, where the metal deposit adheres to the substrate.
Nickel electro-plating – It is a process of depositing nickel onto a metal part. It is a technique of electro–plating a thin layer of nickel onto a metal object. The nickel layer can be decorative, provide corrosion resistance, wear resistance, or used to build up worn or undersized parts for salvage purposes.
Nickel equivalent – It is a calculated value which predicts the austenitic stability of weld metal and the phase type of steel by considering the mass percentages of nickel and other austenite-promoting alloying elements like carbon, manganese, and copper. It is determined by specific empirical equations, such as those found in constitution diagrams like the Schaeffler diagram, which allows for the prediction of phase fields (austenite, ferrite, martensite) by plotting the nickel equivalent and chromium equivalent coordinates.
Nickel-hard iron – Nickel hard is a generic name for white cast iron, alloyed with nickel, chromium, and molybdenum. It is having extremely high strength, abrasion, corrosion resistance, fracture resistance, and toughness. The alloy is best suited to applications in mining, minerals and the iron processing industries. It is ideal for metal-working rolls, grinding mill liners, pulverizer rings, slurry pump parts, grinding media, impact blow bars etc.
Nickel Institute – It is a global association which serves as a centre of excellence for information and guidance on the production and responsible use of nickel. It promotes the use of nickel in several industries and provides a platform for collaboration among nickel producers, fabricators, and users. The institute is known for its research, education, and dissemination of technical information related to nickel and its alloys.
Nickel (II)-iron (III)-oxide – It is normally known as nickel ferrite. It is a mixed-metal oxide with the chemical formula NiFe2O4. It is a type of spinel ferrite, a class of magnetic materials which have a specific cubic crystal structure.
Nickel-iron alkaline rechargeable batteries – These are a type of rechargeable battery which uses nickel oxide-hydroxide as the positive electrode and iron as the negative electrode in an alkaline electrolyte, typically potassium hydroxide. These batteries are known for their robustness, long lifespan, and tolerance for abuse like over-charging and over-discharging, making them suitable for applications needing ruggedness and reliability, such as emergency lighting and off-grid energy storage.
Nickel layer – It is a coating of the metal nickel applied to a substrate, typically through processes like electroplating or electroless plating, to provide benefits such as improved corrosion resistance, improved wear and tear, a decorative glossy finish, or specific magnetic properties. These layers can be decorative, like a mirror finish, or technical, providing protection for industrial parts.
Nickel manganese cobalt – It refers to lithium nickel manganese cobalt oxide, a type of cathode material used in lithium-ion batteries. This layered mixed metal oxide combines nickel, manganese, and cobalt in varying ratios to provide a balance of high energy density (from nickel), structural stability (from manganese), and capacity (from nickel and cobalt). Nickel manganese cobalt batteries are widely used in electric vehicles, consumer electronics, and energy storage systems because of their high energy density and long lifespan.
Nickel mesh – It is a durable, woven, or expanded mesh made from nickel or nickel alloys, valued for its corrosion resistance, high temperature stability, and electrical conductivity. It is used in diverse applications such as battery electrodes, chemical filtration, fuel cell components, and electro-magnetic interference / radio frequency interference shielding. The mesh’s properties, including the precise weave and material purity, dictate its suitability for specific environments and functions.
Nickel-metal hydride (NiMH) battery – It is a type of rechargeable battery which uses nickel oxy-hydroxide for its positive electrode and a hydrogen-absorbing alloy for its negative electrode. The electrodes are immersed in an alkaline electrolyte, typically potassium hydroxide. Nickel-metal hydride batteries offer higher energy density and are more environmentally friendly than nickel-cadmium (NiCd) batteries. They are used in consumer electronics, cameras, and hybrid vehicles.
Nickel mine – It is a site where nickel-bearing ores, specifically sulphide ores or laterite ores, are extracted from the earth for processing and refinement into pure or alloyed nickel. Sulphide ores are typically mined underground, while laterite ores are excavated using surface-mining techniques.
Nickel-olivine catalyst – It is a nickel supported on an olivine mineral catalyst used for high-temperature reactions like methane reforming and biomass gasification, where the olivine acts as a stable support. Key to its effectiveness is the interaction between nickel and the olivine, frequently forming a NiO–MgO solid solution during high-temperature calcination, which improves activity and resistance to carbon deposition and sintering.
Nickel phosphides -These are inorganic compounds composed of nickel and phosphorus, existing in many phases like Ni3P and Ni2P, and are studied for their applications in electro-catalysis, pseudo-capacitors, and alkaline batteries. These earth-abundant materials are valued for their unique electronic properties, high catalytic activity, chemical stability, and anti-corrosion features, making them a low-cost alternative to noble metal catalysts in processes like the hydrogen evolution reaction.
Nickel-phosphorus electroless plating – It is also referred to as E-nickel. It is a chemical process which deposits an even layer of nickel-phosphorus alloy on the surface of a solid substrate, like metal or plastic.
Nickel plating – It is a process where a layer of nickel is applied to the surface of a metal object, typically through electroplating. This coating can be for decorative purposes, improving the appearance and shine of the object, or for functional reasons, like improving corrosion resistance, wear resistance, or even building up worn parts.
Nickel refining – It is the process of purifying crude nickel extracted from its ore into a high-grade, commercially usable form, using methods like electro-winning with acid or chloride solutions, or vapour phase refining through the Mond process, which involves forming and decomposing nickel tetra-carbonyl.
Nickel silver – It consists of copper, nickel and zinc alloys. Their copper content is similar to that of brasses but up to 20 % of the zinc is replaced by nickel. Silvery white in colour they have good corrosion resistance and remain ‘springy’ at moderate temperatures.
Nickel slag – It is the solidified, granulated by-product from the nickel smelting process, mainly composed of non-metallic oxides like silicon di-oxide (SiO2) and magnesium oxide (MgO), and containing valuable elements such as iron (Fe), chromium (Cr), and traces of nickel (Ni). This industrial waste material has gained attention for its potential to be recycled and utilized in several applications, including as a raw material for cement, concrete, glass-ceramics, and in the absorption of electro-magnetic interference (EMI).
Nickel steels – These are the steels which contain nickel as an alloying element. Different quantities of nickel are added to increase the strength in the normalized condition to enable hardening to be performed in oil or air instead of water.
Nickel super-alloy – It is a high-performance metallic alloy with nickel as its main component, designed for extreme high-temperature applications by combining exceptional mechanical strength, creep resistance, fatigue life, and resistance to oxidation and corrosion. These complex, multi-component alloys feature unique micro-structures, frequently with precipitate those phases which improve their durability in harsh environments like jet engines and gas turbines.
Nickel-titanium shape memory alloys – These are frequently called Nitinol. These are a unique class of metallic alloys which show the shape memory effect and super-elasticity. This means they can be deformed at one temperature and return to their original shape upon heating (shape memory effect) or experience large recoverable strains when deformed within a specific temperature range (super-elasticity). These properties, combined with good mechanical properties and corrosion resistance, make them valuable in several applications.
Nickel toxicity – It refers to the adverse health effects caused by exposure to nickel, which can lead to allergic reactions and other physiological issues. The development of nickel-free stainless steel aims to eliminate this risk by replacing nickel with nitrogen, which has been shown to improve the material’s properties without the associated toxicity.
Nickel-zinc (NiZn) rechargeable batteries – These are a type of alkaline battery which uses nickel oxy-hydroxide (NiOOH) and zinc (Zn) as the positive and negative electrodes, respectively, with a potassium hydroxide (KOH) electrolyte. They offer a higher voltage (around 1.65 V per cell) than nickel-metal hydride (NiMH) batteries, making them suitable for high-drain applications.
Nicol prism – It is a prism which is used for polarizing or analyzing light made by cementing together two pieces of calcite using Canada balsam so that the extraordinary ray from the first piece passes through the second piece while the ordinary ray is reflected to the side into an absorbing layer of black paint. No light passes through when two Nicol prisms are crossed. In such a prism the ordinary ray is totally reflected at the calcite / cement interface while the orthogonally polarized extraordinary ray is transmitted. The prism can hence be used to polarize light or analyze the polarization of light.
Ni-Hard – It is a family of high-hardness, abrasion-resistant white cast irons alloyed with nickel and chromium. It is known for its exceptional wear resistance, making it suitable for applications involving abrasive materials and high impact.
Nil-ductility temperature (NDT) – It is defined as the on-heating temperature where ductility is reduced to zero. Essentially, this can be viewed as the temperature of liquation onset, where grain boundary surfaces are coated by a thin continuous liquid film.
Nil-ductility transition temperature (NDTT) – The selection of test temperatures is based on finding, with as few samples as possible, a lower temperature where the sample breaks and an upper temperature where it does not break, and then testing at intervals between these temperatures until the temperature limits for break and no-break performance are determined within 5 deg C. The nil ductility transition temperature is the highest temperature where a sample breaks when the test is conducted by this procedure. Test at least two samples that show no-break performance at a temperature 5 deg C above the temperature judged to be the nil ductility transition temperature.
Nimonic alloy – It is a high-performance, nickel-based superalloy, a family of high-temperature materials designed for applications needing high strength and corrosion resistance at high temperatures, such as in gas turbine blades and other jet engine components. Key additions of chromium, cobalt, titanium, and aluminum provide excellent oxidation resistance and high creep strength at very high temperatures. Nimonic is a registered trademark of Special Metals Corporation.
Nine-inch equivalent – It is a standard unit of volume in refractories industries; 9-inch x 4-1/2-inch x 2-1/2-inch brick.
Niobium (Nb) – It is a light grey, crystalline, and ductile transition metal. Pure niobium has a Mohs hardness rating similar to pure titanium, and it has similar ductility to iron. It increases the yield strength and to a lesser degree the tensile strength of carbon steel. The addition of small quantities of niobium can significantly increase the yield strength of steels. Niobium can also have a moderate precipitation strengthening effect. Its main contributions are to form precipitates above the transformation temperature, and to retard the recrystallization of austenite, thus promoting a fine-grain microstructure having improved strength and toughness. Niobium occurs in association with tantalum (Ta), to which it is closely related. Niobium is a strong carbide-forming element and as such is added to certain austenitic corrosion-resistant steels of the 18/8 chromium-nickel type for the prevention of inter-crystalline corrosion.
Nip – In a bearing, It is the quantity by which the outer circumference of a pair of bearing shells exceeds the inner circumference of the housing. It is also known as crush.
Nip angle – In the rolling of metals, it is the location where all of the force is transmitted through the rolls. It is the maximum attainable angle between the roll radius at the first contact and the line of roll centres. Operating angles less than the angle of bite are termed as contact angles or rolling angles. In roll, jaw, or gyratory crushing, nip angle is the entrance angle formed by the tangents at the two points of contact between the working surfaces and the (assumed) spherical particles to be crushed.
Nip guard – It is an innovative safety apparatus meticulously crafted to shield against potential personnel injuries by obstructing access to the pinch or nip point on the conveyor. Consistent, thorough checks are of paramount importance to uphold the guard’s efficacy in maintaining personnel safety and preventing potential accidents.
Nipple – It is a short stub of pipe normally of threaded steel, brass, chlorinated poly-vinyl-chloride or copper; occasionally just bare copper. A nipple is defined as being a short stub of pipe which has external male pipe threads at each end, for connecting two other fittings. Nipples are normally used for hoses.
Nip point guard – It is a strategically positioned safeguard meticulously devised to eradicate specific points or areas on the conveyor system where injuries could potentially transpire. Periodic inspections play a pivotal role in ensuring the guard’s ongoing effectiveness, actively minimizing the inherent risk of injuries, and fortifying overall safety measures.
Nip rollers – These also known as pinch or laminating rollers. Their main function is to compress and bond multiple sheets of material together to form a laminated product. These rollers are composed of a drive roller and an idler roller working in tandem to exert pressure on materials passed through them. These are pair of rollers which are used in several industrial applications to exert pressure on materials, creating a ‘nip’ point. This nip point is where the rollers come into contact, and it is used to compress, bond, or manipulate materials as they pass between the rollers.
Ni-Resist iron – It is a family of austenitic cast irons known for their excellent corrosion and heat resistance, as well as their high-temperature strength and toughness. These alloys are characterized by their high nickel content, which stabilizes the austenitic structure and enhances their desirable properties. Ni-Resist can be produced with either flake graphite or spheroidal graphite, with the latter normally offering superior mechanical properties.
Nital – It is a solution of nitric acid and alcohol. It is normally used for etching of metals. It is especially suitable for revealing the micro-structure of carbon steels. The alcohol can be methanol or ethanol. Nital is normally used in concentrations of 1 % to 3 % nitric acid (HNO3) in ethanol or methanol. In solutions containing more than 4 % to 5% nitric acid, only methanol is used, since ethanol becomes unstable as the concentration of nitric acid increases. However, nital is not always the best reagent to use to properly reveal all micro-structures.
NiTi alloy – It is also known as Nitinol. It is a nickel-titanium inter-metallic alloy famous for its shape memory and super-elasticity properties. These ‘smart’ characteristics allow the alloy to recover its original shape after being deformed, a phenomenon driven by reversible phase transitions between its low-temperature martensitic phase and its high-temperature austenitic phase. This unique behaviour makes NiTi alloy valuable in several applications.
Nitrate – Nitrate is a polyatomic ion with the chemical formula NO3-. Salts containing this ion are called nitrates. Nitrates are common components of fertilizers and explosives. Almost all inorganic nitrates are soluble in water. Nitrates is found in several different forms in terrestrial and aquatic ecosystems. Nitrates are essential plant nutrients, but in excess amounts they can cause significant water quality problems. Together with phosphorus, nitrates in excess quantities can accelerate eutrophication, causing dramatic increases in aquatic plant growth and changes in the types of plants and animals which live in the stream.
Nitrate fertilizer – It is a type of fertilizer containing nitrate salts, which supply plants with nitrogen. Examples include sodium nitrate and calcium nitrate. While easily absorbed by plants because of high solubility, nitrate fertilizers are prone to leaching into groundwater, leading to pollution and potential harm to livestock if accumulated in crops.
Nitrate removal – It is the process of eliminating nitrate (NO3-) ions from water or other substances, frequently to reduce health risks and environmental impacts, using methods such as biological denitrification, ion exchange, reverse osmosis, or electro-chemical techniques.
Nitrate solution – It is simply a solution where nitrate ions (NO3-) are dissolved in a solvent, typically water. These solutions are formed when a nitrate salt, like sodium nitrate (NaNO3) or potassium nitrate (KNO3), is dissolved in water. Nitrate solutions are widely used in several applications, including as fertilizers, and in laboratories for chemical analysis.
Nitration – It is a chemical process that adds a nitro group (-NO2) to a molecule. This reaction typically involves the substitution of a hydrogen atom in an organic compound for a nitro group and is normally seen in electrophilic substitution reactions, such as the nitration of benzene with a mixture of nitric and sulphuric acids.
Nitric acid – It is an inorganic compound with the formula HNO3. It is a highly corrosive mineral acid. The compound is colourless, but samples tend to acquire a yellow cast over time because of the decomposition into oxides of nitrogen. Majority of the commercially available nitric acid has a concentration of 68 % in water. When the solution contains more than 86 % HNO3, it is referred to as fuming nitric acid. Depending on the amount of nitrogen di-oxide present, fuming nitric acid is further characterized as red fuming nitric acid at concentrations above 86 %, or white fuming nitric acid at concentrations above 95 %. Nitric acid is the primary reagent used for nitration – the addition of a nitro group, typically to an organic molecule. While some resulting nitro compounds are shock-sensitive and thermally-sensitive explosives, a few are stable enough to be used in munitions and demolition, while others are still more stable and used as synthetic dyes and medicines. Nitric acid is also normally used as a strong oxidizing agent.
Nitride -It is a chemical compound of nitrogen. Nitrides can be inorganic or organic, ionic or covalent. The nitride anion, N3- ion, is very elusive but compounds of nitride are many, although rarely naturally occurring. Some nitrides have a found applications, such as wear-resistant coatings (e.g., titanium nitride, TiN), hard ceramic materials (e.g., silicon nitride, Si3N4), and semiconductors (e.g., gallium nitride, GaN). Metal nitrido complexes are also common.
Nitride-carbide inclusion types – It is a compound with the general formula Mx(C,N)y observed normally as coloured idiomorphic cubic crystals, where ‘M’ includes titanium, niobium, tantalum, and zirconium.
Nitride inclusions – These are non-metallic compounds containing nitrogen and a metal, formed during the solidification or processing of metals like steel. These inclusions can negatively impact mechanical properties such as strength and hardness.
Nitride layer – It is a thin surface film composed of a nitride compound, a chemical compound of nitrogen with a more electro-positive element, like silicon nitride or iron nitride. These layers are formed by processes such as nitriding, which hardens surfaces by diffusing nitrogen into metals, or in the fabrication of semi-conductor devices. The specific properties and applications of a nitride layer vary depending on the elements involved and the manufacturing process.
Nitride precipitation – It is the formation of tiny solid particles, or precipitates, of metal nitrides within a metallic matrix. This occurs when nitrogen atoms, frequently introduced during a nitriding process, diffuse into the material and combine with nitride-forming elements, such as iron, chromium, molybdenum, to create these fine, hard nitride particles.
Nitride semi-conductors – These are defined as a class of semi-conductor materials, such as gallium nitride (GaN) and aluminum gallium nitride (AlGaN), which enable the development of high-performance electronic and opto-electronic devices, including light-emitting diodes and lasers, capable of operating in harsh environments.
Nitriding – The nitriding process consists in subjecting machined and heat-treated steel, free from surface decarburization, to the action of a nitrogenous medium, generally ammonia gas, at a temperature of around 500 deg C to 540 deg C. A very hard surface is obtained by this process. The surface-hardening effect is due to the absorption of nitrogen and subsequent heat treatment of the steel becomes not necessary. The time needed is relatively long, normally being 1 day to 2 days. The case, even after 2 days of nitriding, is normally less than 0.5 millimeters. And the highest hardness exists in the surface layers to a depth of only a few hundredth of a millimeter. Special low-alloy steels have been developed for nitriding. These steels contain elements which combine readily with nitrogen to form nitrides. The most favourable of these elements are aluminum, chromium, and vanadium. Molybdenum and nickel are used in these steels to add strength and toughness. The carbon content normally is around 0.20 % to 0.50 %, although in some steels, where high core hardness is necessary, it can be as high as 1.3 %. Stainless steels can also be subjected to nitriding. Since nitriding is carried out at a relatively low temperature, it is advantageous to use quenched and tempered steel as the base material. This gives a strong, tough core with an intensely hard-wear resistant case which is much harder, indeed, than can be obtained by quench hardening either carbonized or cyanided steel. Although warpage is not a problem during the nitriding, steels increase slightly in size during this treatment. Allowance can be made for this growth in the finished article. Protection against nitriding can be achieved by tin, copper, or bronze plating, or by the application of certain paints.
Nitriding steels – These steels are normally suited for the nitriding process. These steels form a very hard and adherent surface upon proper nitriding process (heating in a partially dissociated atmosphere of ammonia gas). These steels have a composition normally containing of carbon in the range of 0.20 % to 0.40 %, chromium in the range of 0.90 % to 1.5 %, molybdenum in the range of 0.15 % to 1 %, and aluminum in the range of 0.85 % to 1.2 %.
Nitrification – It is the biological oxidation of ammonia to nitrate through the intermediary nitrite. Nitrification is an important step in the nitrogen cycle in soil. The process of complete nitrification can occur through separate organisms or entirely within one organism, as in comammox bacteria. The transformation of ammonia to nitrite is normally the rate limiting step of nitrification. Nitrification is an aerobic process performed by small groups of autotrophic bacteria and archaea.
Nitrile – It is an organic compound which has a −C≡N functional group. The name of the compound is composed of a base, which includes the carbon of the −C≡N, suffixed with ‘nitrile’, so for example CH3CH2C≡N is called ‘propionitrile’ (or propane-nitrile). The prefix cyano- is used inter-changeably with the term nitrile in industrial literature. Nitriles are found in many useful compounds, including methyl cyanoacrylate, used in super glue, and nitrile rubber, a nitrile-containing polymer used in latex-free laboratory and medical gloves. Nitrile rubber is also widely used as automotive and other seals since it is resistant to fuels and oils. Organic compounds containing multiple nitrile groups are known as cyano-carbons.
Nitrile chloroprene rubber – The use of nitrile in chloroprene rubber enhances the dynamic properties. It is used for cover rubber which needs high oil and fat resistance whether it be animal, vegetable or mineral and also requiring superior mechanical properties. Nitrile chloroprene rubber is better than chloroprene rubber.
Nitrile-phenolic adhesive – It is a heat-activated, dry-film adhesive formed by blending nitrile rubber and phenolic resin, known for creating strong, permanent bonds with excellent heat, oil, and chemical resistance. It is a thermosetting material, meaning it becomes permanently crosslinked and solidifies under heat and pressure, making it ideal for demanding applications like industrial assembly where high bond strength and durability are needed.
Nitrile rubber – It is a copolymer of butadiene and acrylo-nitrile. It is not resistant to ketones, esters, aromatics, and hydrocarbons. The physical properties are slightly lower than those of natural rubber. The temperature operating range can be controlled between -40 deg C to +120 deg C. It is normally abrasion resistant, resistant to ageing and used for oil and grease resistant belt covers.
Nitro-carburizing – It includes several processes in which both nitrogen and carbon are absorbed into the surface layers of a ferrous material at temperatures below the lower critical temperature and, by diffusion, create a concentration gradient. Nitro-carburizing is performed mainly to provide an anti-scuffing surface layer and to improve fatigue resistance.
Nitrogen (N) – It is a chemical element. It is a non-metal. At standard temperature and pressure, two atoms of the element bond to form N2 which is a colourless and odourless diatomic gas. Nitrogen forms around 78 % of earth’s atmosphere, making it the most abundant chemical species in air. Nitrogen is produced in large quantities and at high purity as a gas or liquid through the liquefaction and distillation of ambient air at the cryogenic air separation plants. It is also produced on commercial scales as a lower purity gas by adsorption technologies (pressure swing adsorption, PSA), or diffusion separation processes (permeation through specially designed hollow fibers). Gaseous nitrogen is called in short as GAN while the liquid nitrogen is called in short as LIN. Liquid nitrogen is a cryogenic liquid. Cryogenic liquids are liquefied gases that have a normal boiling point below – 150 deg C. Liquid nitrogen has a boiling point of -195.8 deg C. Because the temperature difference between the product and the surrounding environment is substantial, it is necessary to keep the liquid nitrogen insulated from the surrounding heat. Nitrogen is frequently stored as a liquid, although it is used primarily as a gas. Liquid storage is less bulky and less costly than the equivalent capacity of high-pressure gaseous storage.
Nitrogen bubbling – It refers to the formation of gaseous nitrogen bubbles from a dissolved state, frequently caused by changes in temperature, pressure, or supercritical conditions, leading to different phenomena such as product protection, and material property changes.
Nitrogen-doped carbon materials – These are carbon-based substances engineered by incorporating nitrogen atoms into their structure, which alters their electronic, catalytic, and surface properties. This doping creates defects and changes the electron density, improving phenomena like carbon di-oxide adsorption, catalytic activity for reactions such as the oxygen reduction reaction (ORR), and electro chemical performance in batteries and super capacitors.
Nitrogen-doped graphene – It is a modified form of graphene where carbon atoms in the honeycomb lattice are replaced by nitrogen atoms, altering its electronic, chemical, and structural properties. This doping process creates nitrogen functional groups like pyridinic, pyrrolic, and graphitic nitrogen, which increase the number of active sites and improve electrocatalytic and electronic conductivity. These improved properties make nitrogen-doped graphene suitable for applications in electro-chemistry, such as fuel cells, and in other fields like energy storage and water treatment.
Nitrogen flush – It is the bubbling of nitrogen gas through a metal melt under vacuum (as with valve bronze) to improve tensile properties and pressure tightness.
Nitrogen flushing – It is the use of high-purity nitrogen gas to create an inert, oxygen-free atmosphere around a metal alloy during high-temperature processes like welding, brazing, and heat treating. This process prevents the formation of oxides and other contaminants which can weaken the final alloy product.
Nitrogen furnace atmosphere – It refers to the use of nitrogen gas within a furnace to create a controlled environment, typically to prevent oxidation or decarburization of materials during heat treatment. Nitrogen, being relatively inert, acts as a protective barrier against reactions with oxygen or other reactive gases in the surrounding air. This controlled environment is crucial for maintaining the desired properties of materials during processes like annealing, sintering, or brazing.
Nitrogen oxides (NOx) – These are a group of gases made up of varying amounts of oxygen (O2) and nitrogen (N2) molecules. Two most important oxides of N2, which are air pollutants, are nitrogen mono-oxide (NO) and nitrogen di-oxide (NO2). These two oxides are frequently lumped together under the designation NOx, although analytical techniques can distinguish clearly between them. Of the two, NO2 is the more toxic and irritating compound.
Nitrous oxide – It is commonly known as laughing gas. It is a chemical compound, an oxide of nitrogen with the formula N2O. At room temperature, it is a colourless non-flammable gas, and has a slightly sweet scent and taste. At high temperatures, nitrous oxide is a powerful oxidizer similar to molecular oxygen. It is a greenhouse gas. It is emitted during agricultural, land use, industrial activities, combustion of fossil fuels and solid waste, as well as during treatment of waste-water. It absorbs 265 times more heat per molecule than carbon di-oxide. Nitrous oxide accounts for around 7 % of the radiative forcing by the long-lived greenhouse gases. It is the third most important individual contributor to the combined forcing. It is emitted into the atmosphere from both natural sources (around 60 %) and anthropogenic sources (around 40 %), including oceans, soils, biomass burning, fertilizer use and various industrial processes.
Nitrogen pick-up – In steelmaking, it is the absorption of nitrogen from the surrounding atmosphere into molten steel, which can affect the steel’s properties. This occurs at various stages of the steelmaking process, from the primary steelmaking such as basic oxygen furnace (BOF) to continuous casting, and can be influenced by factors like the steel grade, deoxidation practices, and stirring methods. The goal is frequently to minimize nitrogen pickup, especially for steels with strict nitrogen content requirements.
Nitrogen purging – It is an industrial process which removes unwanted gases, particularly oxygen and moisture, from systems like pipelines and tanks by displacing them with inert nitrogen gas. This creates a safe, non-reactive environment, preventing problems such as oxidation, corrosion, contamination, and potentially dangerous combustion or explosions.
NLGI – It is the acronym for National Lubricating Grease Institute. This institute describes the different grease grades mainly based on viscosity and, specifically, working penetration testing.
NLGI consistency number – It is also called NLGI grade. It expresses a measure of the relative hardness of a grease used for lubrication, as specified by the standard classification of lubricating grease established by the National Lubricating Grease Institute (NLGI). NLGI’s classification is widely used. The NLGI consistency number is also a component of the code specified in the International Organization for Standardization standard ISO 6743-9. The NLGI consistency number alone is not sufficient for specifying the grease needed by a particular application. However, it complements other classifications (such as ISO 6743-9). Besides consistency, other properties (such as structural and mechanical stability, apparent viscosity, resistance to oxidation, etc.) can be tested to determine the suitability of a grease to a specific application.
N-Methyl-pyrrolidone (NMP) – It is a solvent used in a variety of industries and applications, such as paint and coating removal, petrochemical processing, engineering plastics coatings, agricultural chemicals, electronic cleaning and industrial / domestic cleaning.
N-Methyl-2-pyrrolidone – It is a versatile, polar aprotic solvent which is widely used in industrial, and chemical applications. It is a colourless liquid with strong solvency, a high boiling point, low viscosity, and high resistance to heat and chemicals. It is used in the manufacturing of petrochemicals, and polymers, as well as for applications like nano-material processing, electronics manufacturing, and paint stripping.
No-bake binder – It is a synthetic liquid resin sand binder which hardens completely at room temperature, normally not needing baking. It is used in a cold-setting process.
No-bake binder system – It refers to a method where a chemical binder is mixed with sand to create molds and cores, which then harden at room temperature, eliminating the need for baking or heating the moulds. This system relies on chemical reactions between the binder and a catalyst to achieve self-setting and hardening of the sand mixture.
No-bake process – It is the process of producing moulds / cores with a resin bonded air setting sand. It is also known as the air set process since moulds are left to harden under normal atmospheric conditions.
Noble – It is the positive direction of electrode potential, hence resembling noble metals such as gold and platinum. Noble is a term used to indicate the corrosion resistance, or the lack of it, of a material. If metals are listed in order of their general corrosion resistance, most resistant at the top and going down to the least at the bottom, the higher a metal is in the list the more ‘noble’ it is said to be. When two different metals are connected in a corrosive environment then the least ‘noble’ is attacked preferentially. This effect can be used to protect structures from corrosion buy using a ‘sacrificial anode’ of a less noble metal.
Noble ferro-alloys – These are of high value ferro-alloys which are consumed in low proportions. These ferro-alloys are one of the vital inputs needed for the production of special types of steels and are used as additive inputs especially in the production of alloy and special steels. Noble ferro-alloys are ferro-nickel (Fe-Ni), ferro-molybdenum (Fe-Mo), ferro-vanadium (Fe-V), ferro-tungsten (Fe-W), ferro-niobium (Fe-Nb), ferro-titanium (Fe-Ti), ferro-aluminum (Fe-Al), and ferro-boron (Fe-B). There are some noble ferro-alloys which are having more than one non-ferrous metal as alloying elements. Examples are ferro-silico-magnesium (Fe-Si-Mg), ferro-silico-zirconium (Fe-Si-Zr), and ferro-nickel-magnesium (Fe-Ni-Mg) etc.
Noble gases – These are also called the inert gases. Noble gases are helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), radon (Rn) and, in some cases, oganesson (Og). Under standard conditions, the first six of these elements are odourless, colourless, monatomic gases with very low chemical reactivity and cryogenic boiling points. The properties of the seventh, unstable, element, Og, are uncertain.
Noble metal – It is a metal whose potential is highly positive relative to the hydrogen electrode. It is a metal with marked resistance to chemical reaction, particularly to oxidation and to solution by inorganic acids. The term as frequently used is synonymous with precious metal.
Noble metal thermocouple – It is a type of temperature sensor made from high-precious metal alloys, such as platinum and rhodium, designed for high-temperature applications (up to 1,700 deg C) which need high accuracy, stability, and longevity. These sensors are considerably more expensive than base metal thermocouples but provide exceptional performance in demanding environments like glass manufacturing, semiconductor fabrication, and steel plants.
Noble potential – It is a potential more cathodic (positive) than the standard hydrogen potential.
No cement castable (NCC) – It is deflocculated castable containing a maximum of 0.2 % calcium oxide on a calcined basis and containing no hydraulic setting cement.
Nodal analysis – It is a circuit analysis technique used to determine the voltage at different nodes (junctions) in an electrical circuit by applying Kirchhoff’s current law (KCL) and Ohm’s law to form a system of linear equations. The method defines node voltages as circuit variables, expresses branch currents in terms of these node voltages, and then solves the resulting equations to find the unknown voltages at each non-reference node. It is a technique for analysis of currents in an electrical network.
Nodal diagram – It is a visual representation where ‘nodes’ (points or circles) symbolize entities, and ‘links’ (lines or edges) show the relationships or connections between them. It organizes information to reveal patterns like clusters, key nodes, and relationships, providing a quick overview of interconnected systems such as networks, software architectures, project tasks, or even complex circuits through methods like nodal analysis.
Nodal point – It is either of two points on the axis of a lens or other optical system, determined by extending an incident oblique ray and the corresponding refracted ray to the axis for the pair of rays which are parallel outside the optical system. Some examples of nodal points are (i) the nodal points of a curved interface between two optical media are located at the centre of curvature of the surface, possibly far away from the surface, (ii) for a thin lens, the two nodal points coincide in the center of the length. Therefore, a ray directed to that center will go through the lens without any deflection or parallel offset.
Node – It is a defined point in an electrical network, with some potential relative to a reference node and where currents can be summed. In case of composites, node is the connected portion of adjacent ribbons of honeycomb.
No-draft (draft-less) forging – It is a forging with extremely close tolerances and little or no draft which needs minimal machining to produce the final part. Mechanical properties can be improved by closer control of grain flow and by retention of surface material in the final component.
Nodular cast iron – It is also known as ductile iron or spheroidal graphite iron. It is a type of cast iron where the graphite particles are in the form of small spheres or ‘nodules’ rather than flakes. This nodular structure results from adding small quantities of magnesium or cerium to molten iron, which gives the material considerably higher strength, toughness, ductility, and impact resistance compared to traditional gray cast iron.
Nodular fireclay – It is a rock containing aluminous or ferruginous nodules, or both, bonded by fireclay.
Nodular graphite – It consists of rounded clusters of tempered carbon, such as that obtained in malleable cast iron as a result of the thermal decomposition of cementite. Nodular graphite is characteristic of malleable iron. The graphite of nodular or ductile iron is spherulitic in form, but called nodular.
Nodular graphite iron – The preferred term is ductile iron. It is a cast iron which has been treated while molten with an element such as magnesium or cerium to induce the formation of free graphite as nodules or spherulites, which imparts a measurable degree of ductility to the cast metal.
Nodular iron – It is cast iron, normally gray cast iron, which has the major part of its graphitic carbon in nodular from.
Nodular pearlite – It consists of the pearlite which has grown as a colony with an approximately spherical morphology.
Nodular powder – It is irregular powder having knotted, rounded or similar shape.
No harm threshold – It is the risk of death of 1 in 1 million per annum which is normally considered in the radiation protection community as equating to a dose of 10 micro-Sieverts.
Noise – It is the sounds which can lead to so called noise-induced hearing loss, tinnitus or stress, or interfere with the ability to hear other sounds, to concentrate, to relax or to communicate. Noise is also an undesired signal that tends to interfere with the normal reception or processing of a desired signal. In statistical analysis, noise is a convenient term for a series of random disturbances, or deviation from the actual distribution. Statistical noise is a synonym for error term, disturbance, or random fluctuation. In communication, noise results into breakdown of effective communication breakdown which is caused by different types of noise such as physical noise, linguistic noise, and grammatical noise etc.
Noise abatement – It refers to the reduction of noise levels through the use of urban greenery, such as green roofs and walls, to create a quieter environment and mitigate the health risks associated with noise pollution.
Noise amplitude – It is the level of noise present in a signal, represented as a percentage of the mean signal amplitude, which affects the synchronization of the system. As noise amplitude increases, system synchronization deteriorates and can be destroyed beyond a certain threshold.
Noise barrier – It is a physical structure, such as a wall or berm, designed to block, absorb, or reflect sound, thereby reducing noise pollution from sources like highways, railways, and industrial facilities. These barriers are constructed to create a sound shadow, preventing noise from reaching nearby sensitive areas.
Noise cancelling – It is a type of microphone which preferentially picks up a nearby sound source and rejects ambient noise.
Noise environment – It is an important part of environment impact assessment. Under this included are (i) monitoring the present status of noise levels within the impact zone, and prediction of future noise levels resulting from the proposed project and related activities including increase in vehicular movement, (ii) identification of impacts due to any anticipated rise in noise levels on the surrounding environment, and (iii) recommendations on mitigation measures for noise pollution.
Noise factors – These are factors which are either inherently uncontrollable or impractical to control because of technological / economic reasons. These factors can be further classified into outer noises and inner noises. Outer noise consists of external sources or factors which are operating in the environment in which the product is functioning and whose variation is transmitted through the design to the output performance of the product. Examples of outer noise factors are temperature, humidity, contaminants, voltage fluctuations, vibrations from nearby equipment, and variations in human performance. Inner noise consists of internal change in product characteristics such as drift from the nominal over because of the deterioration. Inner noise can be precipitated by such factors as mechanical wear and aging. In radio frequency (RF) and electronics, noise factor is a measure of how much a component or system degrades the signal-to-noise ratio (SNR) when a signal passes through it. It is essentially a ratio which compares the signal-to-noise ratio at the input to the signal-to-noise ratio at the output. A lower noise factor indicates better performance, meaning the component or system adds less noise to the signal.
Noise level – It is the sound pressure level, normally expressed as dB(A) (audible decibels), emitted by a control valve when operating under specified process conditions. It is also the extent of sound volume produced during the operation of a conveyor system. Regular evaluations are imperative to discern and mitigate heightened noise levels effectively, contributing to the cultivation of a secure and comfortable working environment.
Noise pollution – It is the propagation of noise or sound with potential harmful effects on humans. Noise pollution is normally generated inside several industrial facilities and some other workplaces, but it also comes from highway, railway, and airplane traffic and from outdoor construction activities.
Noise reduction – It is the techniques used to reduce the perception of noise in a communications path. In case off fans, and blowers, noise reduction can be accomplished by several methods like (i) insulating the duct, (ii) mounting the fan on a soft material, such as rubber or suitable spring isolator as needed to limit the quantity of transmitted vibration energy, or (iii) installing sound damping material or baffles to absorb noise energy.
Noise source – It is the point or mechanism which generates unwanted or disruptive signals, such as sound waves in the context of noise pollution, or random electrical disturbances in communication systems. It can be a naturally occurring phenomenon, like thermal motion of electrons in a circuit, or a man-made device, such as a machine or electronic equipment. The key characteristic of a noise source is its production of signals which interfere with or mask a desired signal.
Noise spectrum – It is the distribution of power or energy across different frequencies within a noise signal, which is a random process. This distribution, frequently called the power spectral density (PSD), shows how much energy the noise has at each particular frequency and determines the ‘colour’ of the noise, influencing how it sounds or appears.
Noise standards and limits – These are the guidelines for acceptable sound levels in different environments. These limits are set to reduce the negative effects of noise pollution on people.
Noise suppression – It is a technological process which reduces or removes unwanted background noise from a signal, such as audio or images, to improve the clarity and quality of the desired content. It uses algorithms to differentiate between the intended signal (e.g., speech) and background noise, then selectively attenuates or eliminates the noise components, making the primary signal more understandable. Common applications include enhancing audio for calls in noisy environments, smoothing grainy images, and reducing ambient noise in industrial settings.
Noise zoning – It refers to the classification of areas based on noise levels, or to a model for identifying and removing unwanted components from a sound.
Noisy-channel coding theorem – It is a theorem which establishes the limits of the error-free data transmission in a noisy communication channel.
No-load tap changer (NLTC) – It is also known as an off-circuit or de-energized tap changer. It is a device on a transformer which adjusts the turns ratio to regulate voltage but needs the transformer to be completely disconnected from the power supply to perform the change. Unlike on-load tap changers (OLTCs), this manual process is used only for infrequent voltage adjustments, typically in distribution transformers, to compensate for long-term changes in system voltage.
No-load test – It is a pre-commissioning procedure used to evaluate the performance of equipment, such as motors or transformers, without any load connected to them. This allows for the assessment of core losses, friction and windage losses, and other no-load characteristics. It is a crucial step in commissioning, ensuring the equipment operates as intended before it’s subjected to full operational load.
NOL ring – It is a parallel filament-wound or tape-wound hoop test sample for measuring different mechanical strength properties of the material, such as tension and compression, by testing the entire ring or segments of it. It is also known as a parallel fibre reinforced ring.
Nomex – It is a trade name for an aramid fibre or paper used for honeycomb construction.
Nominal area (of contact) – It is the area bounded by the periphery of the region in which macroscopic contact between two solid bodies is occurring. This is frequently taken to mean the area enclosed by the boundaries of a wear scar, even though the real area of contact, in which the solids are touching instantaneously. It is normally much smaller.
Nominal belt tension – It is the pre-established or recommended tension level designed for a conveyor belt under typical operating conditions. Consistent examinations are essential to sustain optimal belt tension, mitigating issues like slippage and undue wear.
Nominal bore (NB) – This term is frequently used inter-changeably with NPS (North American set of standard sizes for pipes).
Nominal capacity – It is the maximum intended output or storage quantity of a system or device under ideal, specified conditions, as defined by the manufacturer. It differs from the actual or usable capacity, which considers real-world operating conditions and can be lower because of the factors like temperature, pressure, and system inefficiencies. For example, a battery’s nominal capacity is its rated energy at a standard temperature, while a power plant’s nominal capacity is its full-load sustained output.
Nominal cross-sectional area of reinforcement bar – It is the cross-sectional area equivalent to the area of a circular plain bar of the same nominal diameter.
Nominal diameter, Diametre Nominal (DN) – It is the European designation equivalent to NPS (North American set of standard sizes for pipes), in which sizes are measured in millimeters.
Nominal dimension – It is the size of the dimension to which the tolerance is applied. For example, if a dimension is 50 millimeters +/- 0.5 millimeters, the 50 millimeters is the nominal dimension, and the +/- 0.5 millimeter is the tolerance.
Nominal frequency – It is the designed, standard operating frequency of a system or device, like the 50 hertz or 60 hertz standards for power systems, or a 5 mega-hertz label on an oscillator. It serves as a crucial reference point or ideal value, though actual output frequency will naturally vary because of the factors like load changes.
Nominal pipe size (NPS) – NPS is a North American set of standard sizes for pipes used for high or low pressures and temperatures. In this standard ‘NPT’ is used for tapered and ‘NPS’ is used for straight threads to join pipes and fittings. Pipe size is specified with two non-dimensional numbers namely (i) a nominal pipe size based on inches, and (ii) a schedule (Sch.) which specifies the wall thickness.
Nominal power – It is a designated or theoretical power rating, frequently a standard value used for comparison or design, which represents the nameplate capacity of a device under specific, ideal conditions, like a solar panel’s capacity under standard test conditions (STC). This is not the same as the actual, real-world operating power, which is frequently lower because of the factors like heat, and helps designers match equipment, such as solar panels with charge controllers.
Nominal rotational speed – It is the standard, rounded speed a device operates at to deliver its designated power output, such as 2,900 revolutions per minute (rpm) or 1,450 revolutions per minute for a 50 Hertz power supply. It is a practical speed value used for classification and specification purposes, differing from actual operating speeds which can vary depending on load and other conditions.
Nominal scale – It is a variable measured on a nominal scale which is the same as a categorical variable. The nominal scale lacks order and does not possess even intervals between levels of the variable. An example of a nominal scale variable is vehicle type, where levels of response include truck, van, and auto. The nominal scale variable provides the statistician with the least quantity of information relative to other scales of measurement.
Nominal shear strength – It is the theoretical shear capacity of a structural element, calculated as per the established engineering codes and assumptions before any strength-reduction factors are applied. It is determined by summing the contributions from the material itself (like concrete) and any included shear reinforcement (such as steel stirrups). This calculated value serves as a crucial benchmark which is to be higher than the factored shear force to ensure the safety of the structure.
Nominal strain – It is a macroscopic global strain. It is defined with respect to the gauge length over the representative volume element (RVE) (or a whole sample in a material test), while a macroscopic local strain is equivalent to the mesoscopic global strain defined as a measure of the average deformation experienced by each cell (or a row of cells if one-dimensional simplification is adopted).
Nominal strength – It is calculated for a cross-sectional area, taking into account the stress raising effects of the macro-geometrical shape of the component of which the section forms a part, but disregarding the local stress raising effects from the section shape and any weldment or other fixing detail.
Nominal stress – It consists of the stress at a point calculated on the net cross section without taking into consideration the effect on stress of geometric discontinuities, such as holes, grooves, fillets, and so forth. The calculation is made using simple elastic theory.
Nominal temperature – It refers to a standard temperature, typically 25 deg C, used to rate the performance of a device, such as a battery’s capacity or a solar panel’s power output, under specified conditions. It serves as a reference point for manufacturers to establish baseline performance, even though actual operating conditions can differ.
Nominal value – It is the value of input and output which has been stated by the manufacturer of the measuring instruments in the user manual.
Nominal wall thickness – It is the standardized, specified thickness for a component like a pipe, which accounts for manufacturing tolerances and represents an ideal, not an exact, measurement. This standardized value is used in engineering and design as a reference point for calculations and manufacturing, while the actual wall thickness varies within a defined range.
Nomogram – It is also called a nomograph, alignment chart, or abac. It is a graphical calculating device, a two-dimensional diagram designed to allow the approximate graphical computation of a mathematical function. Nomograms use a parallel coordinate system rather than standard Cartesian coordinates. A nomogram consists of a set of ‘n’ scales, one for each variable in an equation. Knowing the values of ‘n-1’ variables, the value of the unknown variable can be found, or by fixing the values of some variables, the relationship between the unfixed ones can be studied. The result is got by laying a straight-edge across the known values on the scales and reading the unknown value from where it crosses the scale for that variable. The virtual or drawn line created by the straightedge is called an index line or isopleth.
Non-aqueous electrolyte – It is an electro-chemical medium whichfacilitates ionic current by using a non-water-based solvent, such as an organic solvent or ionic liquid, instead of water. These electrolytes contain a dissolved salt, providing free-moving ions which act as charge carriers to transport charge between electrodes in devices like batteries.
Non-aqueous fluid – It is a liquid, or solution, in which water is not the solvent. Instead, a non-aqueous fluid uses a liquid other than water, such as oil, alcohol, or other organic compounds, as the base liquid or solvent for a solution or system. These fluids are used in several applications.
Non-automated facility – It is a system or operation which relies on manual, human-driven processes rather than automated or computerized technology. An organization can operate a non-automated facility because of a limited budget, the small scale of the operation, or a desire for higher flexibility.
Non-circular duct – It is a pipe, tube, or channel which conveys a substance (like a fluid) but does not have a circular cross-section, featuring shapes such as rectangles, triangles, or other non-round geometries. Because of the complex fluid flow characteristics in these shapes, engineers frequently use the hydraulic diameter (a measure of the duct’s effective diameter) to approximate flow behaviour and analyze heat transfer and pressure drop.
Non-circular gears – Though frequently overlooked, non-circular gears can provide several types of unusual motion or speed characteristics. Cams and linkages can provide these special motion requirements as well, but non-circular gears often represent a simpler, more compact, or more accurate solution. Common requirements handled by non-circular gears include converting a constant input speed into a variable output speed, and providing several different constant-speed segments during an operating cycle. Other applications need combined translation and rotation, or stop-and-dwell motion. Several types of non-circular gears, particularly elliptical gears, generate variable output speeds. Other, less commonly used types are triangular and square gears.
Non-clogging tail pulley – It is a tail pulley which is meticulously crafted to curtail material build-up and thwart clogging issues. Regular inspections are vital to guarantee the seamless operation and unobstructed material flow on the conveyor.
Non-close packed structure – It is an arrangement of particles which is less dense than a close-packed structure, meaning it has more empty space and larger interstitial voids. Unlike close-packed structures, which can frequently be formed by direct self-assembly, non-close packed structures need specialized techniques like etching, electric-field-directed assembly, or template-guided methods to create.
Non-cohesive sediment – It refers to coarse-grained sedimentary materials, such as sand and gravel, which lack substantial stickiness or cohesion between individual particles. These particles move as independent units under the force of water currents and waves, with their transport governed by their size and friction rather than internal adhesion. This lack of cohesion means they do not form aggregates and are loose and granular, unlike fine-grained sediments which can stick together.
Non-coking coal – It is defined as a type of hard coal which do not have coking properties. This coal is also known as thermal coal, steam coal, or boiler coal. Non-coking coal is that coal which when heated in the absence of air leaves a coherent residue. This residue does not possess the physical and chemical properties of the coke and is not suitable for the manufacture of coke. Non coking coal like any other coal is an organic rock (as opposed to most other rocks in the earth’s crust, such as clays and sandstone, which are inorganic). It contains mostly carbon (C), but it also has hydrogen (H2), oxygen (O2), sulphur (S) and nitrogen (N2), as well as some inorganic constituents which are known as ash (minerals) and water (H2O).
Non-compact section – It is a structural cross-section, frequently steel, which can reach the yield stress in its compression elements before local buckling occurs, but it cannot achieve a full plastic stress distribution needed for a plastic moment. Noncompact sections have a width-to-thickness ratio for their flanges or webs that is greater than the limit for a compact section but less than the limit for a slender section. The design of noncompact sections accounts for the reduction in strength caused by local buckling of the flange or web or by lateral-torsional buckling, which governs the section’s nominal flexural strength.
Non-compliance -It takes place, where legislative requirements, such as those found in an Act, regulation, Code of Practice, or authorization are not met.
Non condensable gas – It is a gas whose temperature is above its critical temperature so that it cannot be liquefied by increase of pressure alone. Non-condensable gas does not turn into a liquid under the specific pressure and temperature conditions of a system. These gases, such as oxygen, carbon di-oxide, and nitrogen, can accumulate and cause problems like reducing heat transfer efficiency, increasing pressure, or hindering system operation.
Non-condensing turbine – It is also known as a back-pressure turbine. It is a type of steam turbine which exhausts steam at a pressure higher than atmospheric pressure. Unlike condensing turbines, which condense exhaust steam into water, non-condensing turbines release the steam for other processes or heating applications.
Non-conductive adhesive – It is an electrically insulating bonding material, typically a polymer or resin, which secures components together without allowing the flow of electrical current. These adhesives, such as specialized epoxies and silicones, are crucial in electronics for providing electrical insulation, mechanical stability, and protection against shorts and interference between sensitive parts.
Non-conformal surfaces – These are the surfaces whose centres of curvature are on the opposite sides of the interface, as in rolling element bearings or gear teeth. In wear testing, non-conformal surface is a geometric configuration in which a ‘point’ or ‘line’ of contact is initially established between samples before the test is started. Examples of non-conformal contacts are ball-on-ring and flat block-on-ring geometries (tangent to the circumferential surface). When wear occurs, the nominal area of contact tends to increase.
Non-conformance – It is a failure to meet one or more established requirements, such as customer expectations, regulatory rules, internal procedures, or quality standards. It signifies a deviation in a product, service, system, or process from its intended specifications, which can lead to issues like decreased quality, operational inefficiencies, or even legal problems. The term is frequently used interchangeably with ‘non-conformity’.
Non-conformance report (NCR) – It is a formal document used in quality management to identify, record, and address deviations from established requirements, standards, or specifications for a product, service, or process. It details the non-conformity, explains how it occurred, and outlines corrective actions to prevent recurrence, playing a crucial role in maintaining quality and compliance within an organization
Non-conforming item – It is a product, material, process, or system which does not meet established requirements, standards, specifications, or customer expectations. These deviations can include visual defects, incorrect dimensions, unmet performance standards, or failures in documentation or procedures, and are documented in nonconforming item is a product, material, process, or system that does not meet established requirements, standards, specifications, or customer expectations. These deviations can include visual defects, incorrect dimensions, unmet performance standards, or failures in documentation or procedures, and are documented in Non-conformance Reports to drive corrective actions and continuous improvement. to drive corrective actions and continuous improvement.
Non-consumable arc melting – It refers to an electric arc melting process where the electrode, typically made of tungsten, does not melt and transfer material into the molten pool during the process. Instead, the electrode serves as a heat source, maintaining an arc that melts the material in a crucible, frequently within a vacuum environment.
Non-consumable welding electrodes – There are two types of non-consumable welding electrodes namely (i) the carbon electrode which is a non-filler metal electrode used in arc welding or cutting, consisting of a carbon graphite rod which may or may not be coated with copper or other coatings, and (ii) the tungsten electrode which is a non-filler metal electrode used in arc welding or cutting, made principally of tungsten. carbon electrodes are of three grades namely (i) plain, (ii) uncoated, and (iii) copper coated. The standard provides diameter information, length information, and requirements for size tolerances, quality assurance, sampling, and various tests. Applications include carbon arc welding, twin carbon arc welding, carbon cutting, and air carbon arc cutting and gouging. Tungsten electrodes are used for gas tungsten-arc (TIG) welding. They are of three types namely (i) pure tungsten, (ii) tungsten containing 1 % or 2 % thorium, and tungsten containing 0.3 % to 0.5 % zirconium. Type of tungsten electrodes can be identified by paint end marks which are green for pure tungsten, yellow for with 1 % thorium, red with 2 % thorium, and brown with 0.3 % to 0.5 % zirconium.
Non-contact bearings – These are the bearings in which no solid contact occurs between relatively moving surfaces. These include fluid bearings and magnetic bearings. The lack of mechanical contact means that static friction can be eliminated, although viscous drag occurs when fluids are present. However, life can be virtually infinite if the external power units needed to operate them do not fail. Strictly speaking, a bearing in which full-film lubrication is occurring would be considered a non-contact bearing. However, this term is more typically applied to gas bearings and magnetic bearings.
Non-contact pyrometry – It is also known as radiation thermometry. It is a method of measuring temperature without physical contact with the object being measured. It works by detecting and analyzing infrared or visible radiation emitted by the object, and then calculating the temperature based on the intensity and wavelength of the radiation.
Non-contact region – It is an area where two objects or surfaces influence each other without any direct physical touch. This concept is applied in different fields, such as tribology, and manufacturing, to describe interactions over a distance.
Non-contact sensor – It is a sensor integrated into conveyor systems which operates without direct physical contact with the material or object being detected. Routine inspections are imperative to ensure precise sensing and avert inaccuracies in readings.
Non-contact switch – It is a safety switch within a conveyor system which is designed to activate without needing physical contact. Regular checks are crucial to ascertain consistent responsiveness and fortify overall system safety measures.
Non-contact ultrasonic – It is a technique which uses ultrasonic sound waves to measure or test a subject without physical contact, unlike traditional methods which need a couplant like gel or water. This is achieved through different technologies, including air-coupled sensors, laser-generated ultra-sound, or electro-magnetic acoustic transducers (EMATs), which allow for remote and faster inspection. Its main applications are in areas where contact is undesirable, such as measuring the level of substances in tanks or performing non-destructive testing on delicate or hard-to-access materials.
Non-conventional fuels – These are alternative energy sources which are not traditional fossil fuels, such as coal, oil, and natural gas. These fuels are often renewable, more environmentally friendly. These include alternatives derived from biomass, waste products, and coal. Examples of non-conventional fuels include bio-mass, bio-diesel, bio-alcohols, and bio-hydrogen, and geothermal energy. They are important for sustainable energy development since they help reduce dependence on finite resources and decrease pollution.
Non-convergence – It is the failure of a process, calculation, or sequence to reach a single, stable result. This can occur in mathematics, where a series does not approach a finite value, or in engineering and statistics, where a simulation or model fails to find a solution within the given parameters.
Non-convex – It describes a property of a set or function which is not convex. A set is non-convex if it is possible to connect two points within the set with a straight line which passes outside the set. A function is non-convex, if its graph between any two points on the , dips below the line segment connecting them, and it can have multiple local minima or maxima.
Non-cryogenic air separation processes – These processes are near ambient temperature separation processes and are used for the production of either nitrogen or oxygen as gases. These processes are cost effective choices when demand of gases is relatively small and when very high purity of the gases is not needed. Non cryogenic air separation plants are compact and produce gaseous nitrogen which is typically 95.5 % to 99.5 % oxygen free or gaseous oxygen which is 90 % to 95.5 % pure. Non-cryogenic plants are less energy efficient than cryogenic plants (for comparable product purity) but at the same time cost less to build. The physical size of the plant can be reduced as required purity is reduced, and the power needed to operate the unit is reduced as well. Non-cryogenic plants are relatively quick and easy to start up and can be brought on line in less than half an hour. This is useful when product is not needed full time. Like cryogenic plants, non-cryogenic air separation processes also start with compression of air. Unlike cryogenic plants which use the difference between the boiling points of nitrogen and oxygen to separate and purify these products, non-cryogenic air separation plants use physical property differences such as molecular structure, size, and mass to produce nitrogen and oxygen. Non-cryogenic processes are based on either selective adsorption or permutation through membranes. The most common technologies used for non-cryogenic air separation plants are adsorption process technology, (ii) chemical process technologies, (iii) membrane separation technology, and (iv) ion transport membrane technology.
Non-crystalline region – It is a part of a material’s structure where the atoms or molecules are arranged in a random, disordered, and haphazard way, lacking the long-range, repeating pattern found in crystals. This is also known as an amorphous structure and is typical of materials like glass or the amorphous phases of polymers and certain elements.
Non-deformable particle – It is a type of a particle which does not change its shape or size, especially under stress or deformation. It is considered as a hard, rigid object which resist deformation, affecting the behaviour of the surrounding material, such as a metal matrix, by influencing dislocation movement and storage. In fluid mechanics, a non-deformable particle (or droplet) is one which maintains its shape despite the fluid flow.
Non-destructive evaluation – It is broadly considered synonymous with non-destructive inspection (NDI). More specifically, it is the quantitative analysis of non-destructive inspection findings to determine whether the material is acceptable for its function, despite the presence of discontinuities. With non-destructive evaluation, a discontinuity can be classified by its size, shape, type, and location, allowing the investigator to determine whether or not the flaw(s) is acceptable. Damage tolerant design approaches are based on the philosophy of ensuring safe operation in the presence of flaws.
Non-destructive examination – It consists of a wide group of analysis techniques which are used in industry to evaluate the properties of a material, component or system without causing damage. Since non-destructive examination does not permanently alter the article being examined, it is a highly valuable technique which can save both money and time in product evaluation, trouble-shooting, and research. The six most frequently used non-destructive examination methods are eddy-current, magnetic-particle, liquid penetrant, radiographic, ultrasonic, and visual testing.
Non-destructive inspection (NDI) – It is a process or procedure, such as ultrasonic or radiographic inspection, for the determination of the quality or characteristics of a material, part, or assembly, without permanently altering the subject or its properties. It is used to find internal anomalies in a structure without degrading its properties or impairing its serviceability.
Non-destructive technique – It is a technique which evaluates a material, component, or system’s properties and integrity without causing damage or permanent alteration. Non-destructive techniques are used to detect defects, ensure quality, and assess condition in industries and manufacturing. Common examples include visual inspection, and X-rays offering a cost-effective way to maintain assets and prevent failures.
Non-developmental item – It is a product or item which has already been developed or needs only minor modifications, frequently available in the market, to meet a customer’s needs.
Non-dimensional mass – It is a measure of mass which has been scaled or normalized so it is no longer tied to any specific units of measurement, such as kilograms. It is created by dividing the mass of an object by a characteristic mass which is intrinsic to the system being studied, frequently resulting in a ratio which simplifies analysis and comparison, particularly in engineering.
Non-dimensional quantity – It is a quantity with no physical units, resulting from a ratio or product of other quantities where all the units cancel out, leaving a pure number. These quantities are useful since they are independent of the system of units used and can simplify complex equations by eliminating dimensions. Examples include strain, which is a ratio of change in length to original length, and dimensionless numbers like the Reynolds number, which compares inertial forces to viscous forces in fluid dynamics.
Non-displacement piles – In these piles the soil is removed when the hole is bored, hence there is no displacement of the soil during installation. The installation of these piles causes very little change in the stresses in the surrounding soil. Bored piles are non-displacement piles.
Non-disclosure agreement (NDA) – It is also known as a confidentiality agreement. It is a legal contract or part of a contract between at least two parties which outlines confidential material, knowledge, or information which the parties wish to share with one another for certain purposes, but wish to restrict access to. Non-disclosure agreement is a contract through which the parties agree not to disclose any information covered by the agreement. An non-disclosure agreement creates a confidential relationship between the parties, typically to protect any type of confidential and proprietary information or trade secrets.
Non-dominated front – It consists a set of solutions in a multi-objective optimization problem where no single solution can be considered better than another when all objectives are considered simultaneously. These solutions represent the best possible trade-offs between conflicting goals, and the most ideal set of such solutions is known as the Pareto optimal front.
Non-dominated solutions – These refer to candidate solutions in a multi-objective optimization problem, where improving one objective function degrades the quality of one or more other objective functions. These solutions are considered Pareto optimal, meaning they are equally good without additional information.
Non-drive end – It is the termination point of the conveyor system where components lack direct connections to the drive unit. Periodic checks are essential to maintain stability and ensure proper alignment on the non-drive end.
Non-edible vegetable oil – It is sustainable alternative to mineral oil which shows improved properties such as lubricity, viscosity, and anti-wear characteristics, contributing to reduced environmental degradation when used as lubricant.
Non-equilibrium – It is a state in which a system is not in a stable, balanced state and is undergoing continuous changes, such as the transfer of energy or matter. This is in contrast to equilibrium, where a system is stable and its properties are uniform throughout. Non-equilibrium can be a temporary state after a system is disturbed, or a permanent condition for systems which are continuously maintained in an unbalanced state.
Non-equilibrium state – It is a condition where a system’s properties change over time and it is not in a state of balance, frequently since there are ongoing flows of energy or matter. Unlike an equilibrium state, where system properties are constant, a non-equilibrium state is dynamic and canbe temporarily displaced from equilibrium by a perturbation, eventually relaxing into a new equilibrium. This imbalance allows for processes like transport and chemical reactions to occur.
Non-equilibrium system – It is one which is not in a state of thermodynamic equilibrium, meaning its properties like temperature and pressure are not uniform or constant across the system. These systems continuously exchange energy and / or matter with their surroundings, preventing them from reaching a stable state of rest and frequently showing phenomena like pattern formation or chemical reactions.
Non-essential variable – It is a condition in welding which can be changed without affecting the mechanical properties of the weldment and does not need a new ‘welding procedure qualification record’ (WPQR). Changes to a nonessential variable only need an amendment to the ‘welding procedure specification’ (WPS). Examples include minor changes in joint design, filler metal diameter, or welding position.
Non-expendable mould casting processes – The non-expendable mould casting is a casting process in which the mould need not be reformed after each production cycle. Non-expendable mould casting is a casting technique which has at least 4 distinct casting processes. These are (i) continuous casting, (ii) centrifugal casting, (iii) die casting, and (iv) permanent mould casting. This form of casting also results in improved repeatability in parts produced and delivers near net shape casting.
Non-faradaic process – It is an electro-chemical process an electrode-solution interface which does not involve a direct transfer of electrons, meaning there is no oxidation or reduction reaction. Instead, it involves the accumulation of charge to form an electrical double layer, similar to a capacitor, which can be charged and discharged without changing the chemical composition of the electrode. This process is driven by the capacitive effect at the interface.
Non-ferrous – It is a negative term, refers to alloy in which the predominate metal or solvent is not iron.
Non-ferrous alloy – It is a metal mixture which does not contain iron (Fe) or only contains trace quantities of it. These alloys are valued for their specific properties like lightness, high conductivity, or corrosion resistance, making them useful in several applications where iron-based alloys are not suitable.
Non-ferrous metal casting – It is the metal casting done with a non-ferrous metal, in which the molten metal is poured into a mould, cooled, and allowed to solidify.
Non-ferrous metal processing – It is the processing of a non-ferrous metal, such as by melting, alloying, or casting.
Non-ferrous metals – These are metals or alloys which do not contain iron (allotropes of iron, ferrite, and so on) in appreciable quantities. Normally more costly than ferrous metals, non-ferrous metals are used because of desirable properties such as low weight (e.g., aluminum), higher conductivity (e.g., copper), non-magnetic properties or resistance to corrosion (e.g. zinc). Some non-ferrous materials are also used in the iron and steel industries. For example, bauxite is used as flux for blast furnaces, while others such as wolframite, pyrolusite, and chromite are used in making ferrous alloys. Important non-ferrous metals include aluminum, copper, lead, tin, titanium, and zinc, and alloys such as brass. Precious metals such as gold, silver, and platinum and exotic or rare metals such as mercury, tungsten, beryllium, bismuth, cerium, cadmium, niobium, indium, gallium, germanium, lithium, selenium, tantalum, tellurium, vanadium, and zirconium are also non-ferrous. They are normally obtained through minerals such as sulphides, carbonates, and silicates. Non-ferrous metals are normally refined through electrolysis.
Non-ferrous slag – It is a byproduct of smelting nonferrous metals like copper, lead, nickel, and zinc, produced when separating metals from ore. This molten material consists of silicates and other compounds and solidifies into a rock-like or granular form after cooling. It is frequently rich in iron, calcium, and silica.
Non-ferruginous wastes – These are the waste materials which do not contain iron. Examples of non-ferruginous waste are lime and dolomite dust and fines, coal and coke dust, sludge (lime sludge, tar sludge, biological treatment sludge, oil sludge, and sewage sludge etc.), non-ferrous scrap, refractory wastes, ironmaking and steelmaking slag, ash (fly ash and bottom ash), and muck, and debris etc.
Non-fill (under-fill) – It is a forging condition which occurs when the die impression is not completely filled with metal.
Non-fired refractory bricks – These are refractory materials which can be used directly without firing. They have the advantages of energy saving, good thermal shock stability, and simple process, and can replace fired refractory products in a wide range of fields.
Non-fluoborate – It is tin-lead electro-plating solution. Non-fluoborate solution are stannous methane sulphonate with lead methane sulphonate, methane sulphonic acid, grain refiners (wetting agents), anti-oxidants, and fungicides. These components, as well as various addition agents, are available in commercial quantities. The solution operates at 100 % cathode and anode efficiency.
Non-fluxed sinter – It is also called acid sinter. It is a type of sintered iron ore produced without adding any flux material to the iron ore mix. It has no or very little added flux (like lime) and is characterized by a high basicity (CaO/SiO2) since the fluxing agents needed to neutralize the acidic components are not included in the sinter mix itself.
Non-friable asbestos products – These are made from a bonding compound (such as cement) mixed with a small proportion (normally less than 15 %) of asbestos. Non-friable asbestos products are solid, rigid and non-friable, and cannot be crumbled, pulverized or reduced to powder by hand pressure. The asbestos fibres are tightly bound in the product and are not normally released into the air.
Non-fusion welding – It is a method in which similar or dissimilar metals are joined together without melting the edges of the base metal by using a low melting point filler rod but without the application of pressure.
Non-functional requirements – These requirements specify the qualities and characteristics of a system, such as its performance, security, and usability, defining how a system performs rather than what it does. They are the operational criteria which a system is required to meet to be effective and meet user and stakeholder needs, influencing factors like speed, reliability, and resilience.
Non-Gaussianity – It is the departure of a probability distribution from a normal (Gaussian) bell curve. This deviation can be quantified using measures like negentropy and indicates that the data is not symmetrically distributed around the mean. Instead, it is often asymmetric, meaning it can be ‘skewed’ with a different shape, such as one with more extreme values or complex dynamics.
Non-Gaussian signal – It is a signal whose probability distribution does not follow a Gaussian (or normal) distribution, deviating from the typical bell curve. These signals can be informational or noise and are analyzed using methods like higher-order statistics, which are necessary since a Gaussian signal can be completely characterized by its mean and variance, while a non-Gaussian signal cannot.
Non-hazardous waste – It is a waste which causes no harm to human or environmental health. Although non-hazardous waste does not sound like it poses a threat, this type of waste can cause significant environmental damage. This type of waste can be subject to certain management requirements. Further it has cost implication since its generation has effect on the yields, and also its disposal has a cost attached to it.
Non-heat treatable alloy – It is an alloy which is incapable of being strengthened by thermal treatment. Non-heat treatable alloys gain their strength from cold-working.
Non-homogeneity – In the context of functions or equations, it means that not all terms have the same degree (or are not of the same homogeneous form) when multiplied by a constant. Specifically, if a function or equation is not homogeneous, it cannot be expressed in a way, where scaling all variables by the same constant results in the function or equation being scaled by that constant raised to a specific power.
Non-homogeneous flow – It is a type of fluid flow where the properties, such as velocity or density, are not uniform across the flow area or over time. This can be caused by variations in the physical boundaries, like a narrowing pipe, or by the uneven distribution of different phases (like gas and liquid) within the fluid itself. As a result, the fluid’s behaviour is spatially dependent, meaning its characteristics change from one point to another.
Non-homogeneous material – It is a material which has non-uniform physical properties. For example, its density at one location can be different from another. Non-homogeneous materials are also known as heterogeneous materials.
Non-hydraulic cement – It is a less common form of cement for example slaked lime (calcium oxide mixed with water), which hardens by carbonation in contact with carbon di-oxide, which is present in the air (around 0.04 %).
Non-hydro-carbon gas – It is a gaseous substance which does not consist of hydro-carbons, meaning it does not contain both carbon and hydrogen atoms. These gases are frequently found as impurities in natural gas and can include compounds like carbon di-oxide (CO2), hydrogen sulphide (H2S), and nitrogen (N2), as well as noble gases such as helium (He) and argon (Ar).
Non-hygroscopic – It means of lacking the property of absorbing and retaining an appreciable quantity of moisture (water vapour) from the air.
Non-interacting system – It is a system where the components or sub-systems do not affect each other’s dynamics or behaviour, allowing for a straight-forward, sequential relationship between variables. In contrast, an interacting system is one where the behaviour of one component directly influences another, making their mathematical analysis more complex.
Non-intrusive measurement technique – It is a method for assessing a system or phenomenon without physically penetrating or altering it, which minimizes or eliminates interference with the subject being measured. This approach allows for data collection while preserving the integrity of the object or system, making it useful in applications like engineering, and scientific research. Examples include using optical or ultrasonic methods instead of physical probes.
Non-invasive studies – These studies are carried out to get underground information without drilling or removable of the surface earth. These studies are similar to someone using a metal detector to find discarded coins on a beach. The larger-scale geophysical studies used by mining organizations can include seismic, gravity, magnetic, or other surveys.
Non-inverting amplifier – It is an operational amplifier circuit where the output signal has the same phase as the input signal, resulting in a positive voltage gain. The input signal is applied to the non-inverting (+) terminal, and the output is amplified without inversion, meaning a positive input produces a positive output. The voltage gain is determined by the ratio of the feedback resistor (Rf) to the input resistor (Ri) and is calculated with the formula Av = 1 + Rf/Ri.
Non-ionic detergent – It is a detergent which produces aggregates of electrically neutral molecules with colloidal properties.
Non-isentropic expansion – It is a thermodynamic process where a fluid expands irreversibly, causing its entropy to increase. This is in contrast to an ideal, reversible isentropic expansion, which maintains constant entropy. In a non-isentropic expansion, inefficiencies like friction lead to a higher final temperature and lower work output than in an isentropic process.
Non-isothermal condition – It is a process or system where temperature varies across different points in space or over time. Unlike isothermal conditions, which assume constant temperature, non-isothermal conditions account for temperature gradients, which can considerably influence properties like density and viscosity, and are common in several engineering and chemical processes.
Non-isothermal hot die forging – It is a metal-working process where the work-piece and dies are not maintained at the same temperature during deformation. This results in a temperature gradient between the work-piece and dies, causing heat transfer and affecting the material flow and deformation behavior. Unlike isothermal forging where temperatures are kept constant, non-isothermal forging involves a dynamic temperature variation throughout the process.
Non-isothermal phase transformations – These transformations refer to phase transitions which occur while the temperature of the material is changing, rather than at a constant, or isothermal, temperature. In simpler terms, it is a phase change happening during heating or cooling, rather than at a specific, fixed temperature.
Non-isothermal side-pressing test – It conducted in a non-isothermal manner can also be used to detect flow localization. Several test samples are side-pressed between flat dies at several work-piece temperatures, die temperatures, and working speeds. The formation of shear bands is determined by metallography. Flow localization by shear band formation is more likely in the side-pressing test than in the upset test. This is because of the absence of a well-defined axisymmetric chill zone. In the side-pressing of round bars, the contact area starts out as 0 and builds up slowly with deformation. In addition, since the deformation is basically plane strain, surfaces of zero extension are present, along which block shearing can initiate and propagate. These are natural surfaces along which shear strain can concentrate into shear bands.
Non-isothermal upset test – It is the simplest workability test for detecting the influence of heat transfer (die chilling) on flow localization, in which the dies are much colder than the work-piece. Flow localization zones are to be made visible by sectioning and metallograhic preparation.
Non-linear association – It is an association between two quantitative variables in which the scatter plot does not follow a linear trend.
Non-linear control – It is the class of control problems relating to the control of systems which are non-linear.
Non-linear crystal – It is a material with optical properties which are dependent on the intensity of the light passing through it, unlike linear materials where the response is proportional to the light intensity. These crystals can alter light’s properties, such as its frequency, by converting it into new wavelengths, and they are necessary for applications like frequency conversion and laser manufacturing.
Non-linear elastic materials – These are substances which deform when a force is applied but return to their original shape once the force is removed, with the relationship between stress and strain not being a straight line. This means the material’s stiffness can change as it deforms, unlike linear elastic materials where stress is directly proportional to strain. Examples include polymers, and certain plastics.
Non-linear equilibrium equation – It is a mathematical expression which describes a system’s balance of forces, where the relationships are not linear, meaning the system’s response does not scale proportionally with the input. Unlike linear equations, non-linear equations have variables with exponents higher than one or are involved in other non-linear terms, and their stiffness matrix can change with each step of an analysis. Solving these equations frequently needs iterative methods and can be complex, especially in fields like structural and mechanical engineering.
Non-linear feedback – It is a control mechanism where the output of a system is not directly proportional to the input, leading to disproportionate or unexpected responses. This occurs in systems where a change in one variable can cause a substantial, non-linear effect on another, frequently resulting in complex dynamics, instability, or a shift to a new state. Unlike linear feedback, which has a predictable, proportional relationship, non-linear feedback needs specialized design methods since its behaviour is dependent on the specific operating point.
Non-linear filter – It is a signal processing method where the output is not a simple linear function of the input, meaning it does not follow the principle of superposition. This allows nonlinear filters to perform more complex operations, such as removing certain types of noise (like impulsive noise) while preserving features like edges in images, which linear filters can struggle with. An example is the median filter, which replaces a pixel’s value with the median of its neighbours.
Non-linear function – It is a mathematical function whose graph is not a straight line and whose rate of change (slope) is not constant. Unlike linear functions, which have a constant rate of change and produce a straight line, nonlinear functions can curve and have a changing slope. Examples include polynomial, exponential, and trigonometric functions.
Non-linear interaction effect – It is an interaction effect in which the non-linear relationship between the study end point and an explanatory factor takes on different shapes over levels of another explanatory variable.
Non-linearity – It means a relationship where the output is not directly proportional to the input, i.e., a change in one variable does not cause a corresponding, constant change in the other. This is frequently represented by a curve instead of a straight line on a graph, indicating that the relationship between variables changes over time.
Non-linear load – It is an electrical device which draws current in a way that is not directly proportional to the voltage, causing the current waveform to be distorted and generate harmonics. Common examples include electronics with switched-mode power supplies (SMPS) like computers, printers, and televisions, as well as variable-speed drives. This contrasts with linear loads, where the current waveform is a direct, sinusoidal reflection of the voltage waveform.
Non-linear model – It is a statistical model which is not linear in the parameters, e.g., the logistic regression model, the Poisson regression model, the proportional hazards model.
Non-linear optical phenomenon – It is an effect where the optical properties of a material change in a way which is not directly proportional to the intensity of the light passing through it. These phenomena occur when the material’s response to an intense light source, typically a laser, depends non-linearly on the light’s strength, leading to changes in the light’s frequency, phase, or polarization. A classic example is second-harmonic generation, where the output light has double the frequency (half the wavelength) of the input light.
Non-linear parameter – It is a parameter in a model where the function is not linear with respect to that parameter, meaning its output does not change proportionally to the parameter’s change. Unlike linear parameters, they need an iterative, numerical algorithm and initial guesses to find the best fit, as there is no direct algebraic solution.
Non-linear phase shift – It is an intensity-dependent change in a signal’s phase as it travels through a medium, unlike a linear phase shift where all frequencies are delayed by the same quantity. This phenomenon is caused by non-linear effects, such as the Kerr effect, where the medium’s refractive index changes with the intensity of the light, leading to different phase shifts for different parts of the signal. It is a fundamental concept in nonlinear optics and is crucial for technologies like optical modulators and sensors.
Non-linear region – It is a state or system where the response is not directly proportional to the input, meaning it does not follow a straight line on a graph. This occurs since the relationship between excitation and response is complex, and the principles of linearity, such as superposition and additivity, do not apply. Examples include materials that have exceeded their yield point, leading to permanent deformation, or systems where the geometry changes considerably with load.
Non-linear relation – A non-linear relation is one where a scatter plot between two variables X1 and X2 does not produce a straight-line trend. In several cases a linear trend can be observed between two variables by transforming the scale of one or both variables. For example, a scatter plot of log(X1) and X2 can produce a linear trend. In this case the variables are said to be non-linearly related in their original scales, but linear in transformed scale of X1.
Non-linear relationship – Non-linear relationship between variables means their connection cannot be represented by a straight line on a graph. Instead, the relationship changes direction or rate, meaning a change in one variable does not always cause a proportional change in the other. This is in contrast to a linear relationship where a constant change in one variable results in a proportional change in the other.
Nonlinear system – It is a system where the output is not directly proportional to the input, meaning it does not obey the principle of superposition. The behaviour of these systems is complex and can show phenomena like chaos, where small changes in initial conditions lead to large differences in outcomes. Unlike linear systems, their response depends on the input size, initial conditions, and other factors.
Non-lubricated hot extrusion – It is a metal forming process where a heated billet is forced through a die without the use of a lubricant to reduce friction between the billet and tooling. While lubricants are typically used to prevent the billet from sticking to tooling like the ram, they are not used to reduce friction between the billet and the die itself in this process. This method is frequently used for complex shapes and tight dimensional tolerances.
Non-magnetic materials – Such materials have little reaction to magnetic fields. They can be composed of molecules where electrons spinning one way are always balanced by electrons spinning the other, or their spins can simply interact only weakly.
Non-magnetic particle – It is a particle which is not attracted to a magnet and cannot be magnetized itself. These particles do not respond to external magnetic fields and are unaffected by them. Examples include wood, plastic, paper, and glass.
Non-magnetic steels – These are steels which have a stable fully austenitic micro-structure.
Non-martensite phases – These phases refer to any microstructural constituents other than martensite which form during the transformation of austenite upon cooling. These phases typically arise when the cooling rate is not rapid enough to prevent diffusion-based transformations, leading to the formation of structures like bainite or ferrite, instead of the desired martensite.
Non-martensitic transformation product (NMTP) – It comprises all micro-structural features other than martensite which transform from austenite upon cooling when a fully martensitic micro-structure is intended.
Non-metal – It is a chemical element which mostly lacks distinctive metallic properties. Non-metals range from colour-less gases like hydrogen to shiny crystals like iodine. Physically, they are normally lighter (less dense) than elements which form metals and are frequently poor conductors of heat and electricity. Chemically, non-metals have relatively high electro-negativity or normally attract electrons in a chemical bond with another element, and their oxides tend to be acidic.
Non-metallic bush bearings – These are slider bearings which use fabric base moulded section. These bearings are normally preferred over the gun metal bearings. The most popular non-metallic bush bearing which is normally used in low-capacity rolling mills is the fibre bearing. The non-metallic bush bearings provide good bearing for rolls having considerable speed variation or where reversal of rotation can take place. The co-efficient of friction is lower in these bearings when compared with the co-efficient of friction of slider bearing with metal bush. Due to the inherent properties, fabric base moulded bush bearings have a low co-efficient of friction, low wear and tear, low maintenance costs, good impact strength, and longer life resulting in higher rate of production. These bearings can with-stand operational temperatures which are in the range of 80 deg C to 120 deg C. Beyond these temperatures fibre bearings generally get charred. Water is used as a general source for lubrication on fibre bearing. These bearings are cheaper than metallic slider bearings and have higher load carrying capacities. Fibre bearings offer better abrasion resistance and do not need machining. These bearings are of light weight and hence easy to handle. They have peculiar frictional behaviour. They are easy to slide when wet and hard to slide when dry.
Non-metallic gaskets – For these gaskets, sheet materials are used in low to medium pressure services. With careful selection, these gaskets are not only suitable for general service but also for extreme chemical services and temperatures. Examples of these gaskets are elastomers, cork, compressed fibre sheets, poly tetra fluoro ethylene (PTFE), bi-axially orientated reinforced PTFE, graphite, thermiculite, and insulating gaskets etc.
Non-metallic impurities – These are also known as non-metallic inclusions. These are undesirable, solid compounds or elements which are present within a metal or alloy, but are not metallic in nature. These inclusions are typically oxides, sulphides, or nitrides, and they can form during the manufacturing process, such as melting and casting. While they exist in small quantities, they can impact considerably the material’s properties. Non-metallic impurities are mainly composed of non-metallic elements like oxygen, sulphur, and nitrogen, frequently combined with metallic elements to form compounds like oxides, sulphides, and nitrides.
Non-metallic inclusions – These are also called simply inclusions. These consist of a physical and mechanical discontinuity occurring within a material or part, normally consisting of solid, encapsulated foreign material. Inclusions are frequently capable of transmitting some structural stresses and energy fields, but to a noticeably different degree than from the parent material. Non-metallic inclusions are also particles of foreign material in a metallic matrix. The particles are normally compounds, such as oxides, sulphides, or silicates, but can be of any substance which is foreign to (and essentially insoluble in) the matrix. Non-metallic inclusions can be exogenous inclusion, indigenous inclusion, or stringer.
Non-metallic ores – These are mineral resources that do not contain substantial quantities of metallic elements and are used for their industrial or chemical properties. Unlike metallic ores, which are mined for extractable metals, non-metallic ores are valued for characteristics like their use in cement, refractories, insulation, and fertilizer production. Examples include limestone, dolomite, mica, gypsum, and quartz.
Non-metallic oxide – It is a chemical compound formed when a non-metal element reacts with oxygen. These compounds are typically covalent and show acidic properties, meaning they react with water to form acids or react with bases to form salts and water. Common examples include carbon di-oxide (CO2), sulphur di-oxide (SO2), and nitrogen di-oxide (NO2).
Non-metallic stringers – These stringers refer to elongated, string-like inclusions of non-metallic compounds within a metallic material, normally steel. These inclusions are typically formed during the manufacturing process and can affect the material’s properties, especially its strength and ductility.
Non-methane hydrocarbons (NMHC) – These are all hydrocarbon air pollutants except for methane. This group includes reactive gases like ethane, propane, and benzene, which are released from both natural and man-made sources like vehicle exhaust and industrial emissions. Non-methane hydrocarbons are important since they are key precursors to the formation of tropospheric ozone and can adversely affect human health.
Non methane volatile organic compounds (NMVOC) – These compounds consist of a group of chemicals which exclude methane. These compounds contain the element carbon in their molecular structure, i.e., they are ‘organic’. They easily vaporize at room temperature and majority of them have no colour or smell. Non methane volatile organic compounds include, in general, the alcohols, aldehydes, alkanes, aromatics, halocarbons and ketones and halogenated derivatives of these substances.
Non-mineral inorganic substance – It is a chemical compound which is inorganic (lacks carbon-hydrogen bonds) but is not a mineral since it is either not naturally occurring or lacks the other specific properties of a mineral, such as a definite crystal structure. This category includes synthetic compounds like brass or bronze, an alloy which does not occur naturally, or ionic salts dissolved in water, such as sodium chloride (NaCl).
Non-Newtonian fluid – It is a fluid whose viscosity (resistance to flow) is not constant and can change depending on the applied force or stress. Unlike Newtonian fluids, where viscosity is constant and independent of shear rate, non-Newtonian fluids show complex flow behaviour, with their viscosity potentially increasing or decreasing under stress.
Non-Newtonian fluid mechanics – It is the study of fluids with variable viscosity, meaning their resistance to flow changes when a force or stress is applied. Unlike Newtonian fluids, which have a constant viscosity (like water), non-Newtonian fluids can become more or less viscous depending on the stress, leading to non-linear flow behaviour. This field examines the complex flow patterns of these fluids, which are common in both nature and industry, for example, in substances like paint.
Non-Newtonian viscosity – It is the apparent viscosity of a material in which the shear stress is not proportional to the rate of shear.
Non-Newtonian wetting – It refers to how non-Newtonian fluids (fluids which do not follow Newton’s law of viscosity) spread on or interact with a surface. It is essentially the study of how these fluids, whose viscosity can change with stress, behave when they come into contact with a solid. This behaviour can be quite complex and differs from the wetting of Newtonian fluids, where viscosity remains constant.
No-node – It is an electron device (although practically, only vacuum tubes) with nine internal active electrodes controlling electron flow.
Non-oriented electrical steel (NOES) – Non-oriented electrical steel can be fully processed or semi processed. Non-oriented, fully processed electrical steel has varying silicon levels which range from 0.5 % silicon to 3.25 % silicon. It has uniform magnetic properties in all directions. This type of electrical steel does not need recrystallization processes to develop its properties. The low silicon alloy grades provide better magnetic permeability and thermal conductivity. For high alloy grades, better performance is expected in high frequencies, with very low losses. This type of steel is good for the magnetic circuits in motors, transformers, and electrical system housing. This fully processed type provides difficulty in punchability because of a completed annealing process. Organic coatings are added to improve lubrication in the punching process. Non-oriented semi-processed electrical steels are largely non-silicon alloyed steel and are annealed at low temperatures after the final cold rolling. The end-user, however, has to provide the final stress-relief annealing as per the intended application of the steel. The punchability of this type of the electrical steel is better than the non-oriented fully processed type, so organic coatings are not needed. Non-oriented semi-processed grades are good core materials for small rotors, stators, and small power transformers. Non-oriented electrical steel is the mostly used material among all soft magnetic materials. It is functional material for the generation of energy as well as for the use of electrical energy in electrical machines and components. The relevant magnetic properties (magnetization behaviour and magnetic losses) of the non-oriented electrical steel are determined by the intensities of the texture components and the inhomogeneity of the micro-structure of the finally processed material (grain size distribution, precipitations, and internal stresses). The number of the processing steps and the process parameters differ remarkably for the non-oriented electrical steel compared to the grain-oriented electrical steel. The processing steps after casting comprises of hot rolling, cold rolling and final annealing. Product and process development in the field of non-oriented electrical steel is characterized, like for the grain-oriented electrical steel, by optimization of the magnetic properties and other physical properties for special application areas as well as by the developments.
Non-oxide ceramics – These are obtained by reacting a metal, or a semi-metal in some cases, with oxygen-free elements such as, sulphur, nitrogen, carbon, boron, phosphorus, arsenic, antimony, selenium, and tellurium. Unlike oxides, barring diamond and graphitic as well as many of the amorphous carbons, these compounds of non-oxide ceramic systems constitute some of the largest manmade substances.
Non-oxide refractories – These are refractories which do not have oxygen in their chemical composition. Example of non-oxide refractories are carbon-based refractory materials, and carbides, nitrides, borides, and silicides. This group also includes sialons which are the silicon nitride sinterable derivatives.
Non-parametric technique – It is a statistical method which does not assume the data comes from a specific probability distribution, which is why it is also called a ‘distribution-free’ test. These methods analyze data based on ranks or frequencies rather than the actual numerical values, making them useful for data which is ordinal, ranked, or does not meet the assumptions of parametric tests, such as normality. Common examples include the Chi-square test, the Wilcoxon rank sum test, and Spearman’s rank-order correlation.
Non-parametric test – It is a statistical test which makes very few assumptions about population distributions.
Non-perishable tooling – It refers to tools which are durable and not consumed or considerably degraded through normal use, allowing for extended use or repair rather than replacement. Unlike perishable tools like drill bits or saw blades, non-perishable tools are typically designed for long-term use and can be refurbished or maintained over their lifespan. Examples include tool holders, fixtures, and power tools.
Non-point sources – These sources of water pollution are those which arrive from different sources of origin and are usually scattered or spread over large areas. These types of sources deliver pollutants indirectly through environmental changes and account for majority of the contaminants in streams and lakes. For example, the contaminated water which runs off from agriculture farms, construction sites, abandoned mines, and acid rains enters streams and lakes. It is quite difficult to control non-point sources.
Non-polar compound – It is a compound consisting of covalent molecules with no permanent dipole moment.
Non-porous membrane – It is also known as a dense membrane. It is a thin film which separates substances by diffusion rather than by size-based filtration. It has very small pores or no pores at all, and its separation performance relies on the difference in solubility and diffusivity of molecules passing through the material itself. These membranes are used in processes like reverse osmosis, nano-filtration, and highly selective gas separations.
Non-positive displacement pumps – These pumps are also known as hydro-dynamic pumps. In these pumps the fluid is pressurized by the rotation of the propeller and the fluid pressure is proportional to the rotor speed. These pumps cannot withstand high pressures and generally used for low-pressure and high-volume flow applications. The fluid pressure and flow generated is due to inertia effect of the fluid. The fluid motion is generated due to rotating propeller. These pumps provide a smooth and continuous flow but the flow output decreases with increase in system resistance (load). The flow output decreases because some of the fluid slip back at higher resistance. The fluid flow is completely stopped at very large system resistance and thus the volumetric efficiency becomes zero. Therefore, the flow rate not only depends on the rotational speed but also on the resistance provided by the system. The important advantages of non-positive displacement pumps are lower initial cost, less operational maintenance because of lesser moving parts, simplicity of operation, higher reliability, and suitability with wide range of fluid etc. These pumps are primarily used for transporting fluids and find little use in the hydraulic or fluid power industries. Centrifugal pump is the common example of non-positive displacement pumps.
Non-powered rollers – These are rollers in a conveyor system which are devoid of a dedicated power source, relying on external forces for movement. Regular inspections are crucial to assess wear, alignment, and overall functionality.
Non-prismatic design – It is a design where the cross-section (shape and / or size) changes along the length of the object. Unlike a prismatic beam which has a constant cross-section, a non-prismatic design allows for optimization of material usage and structural performance by tailoring the geometry to the specific loads and requirements at different points.
Non-probability sample – It is a sample which is not a probability sample, i.e., a hand-picked sample, a convenience sample, or a ‘snowball sample’, etc. Study results using this type of sample can only be generalized to a hypothetical population.
Non-process waste – These are the waste materials which are generated from sources other than the process lines (during the production process). Examples of non-process waste materials are rubber, packing materials, electric wires, plastics and glass, and office and canteen wastes, etc.
Non-processible waste – It means solid waste which cannot be processed at a processing facility because of the physical characteristics of the solid waste or potential harmful effects to the processing facility.
Non-proportional hardening – It is the additional hardening which occurs in a material under cyclic, multi-axial (multi-directional) loading which is not proportional, meaning the ratio between the changes of loads over time. This extra hardening is caused by the activation of multiple slip systems in the material’s micro-structure because of the rotation of principal stress directions during the load cycle.
Non-proportional loading – It is a type of loading where loads are applied sequentially and the ratio between them is not constant. This results in changes in the direction of principal stresses, which can lead to complex material behaviours like ‘non-proportional hardening’ and is frequently seen in real-world engineering applications where multiple loads are applied in a non-synchronized way.
Non-random sample – It is a sample selected by a non-random method. For example, a scheme whereby units are self-selected yields a non-random sample, where units which prefer to participate do so. Some aspects of non-random sampling can be overcome, however.
Non-reactive – It means something which does not react or show a response to a stimulus or condition. It describes substances which are inert or do not easily undergo chemical reactions.
Non-recovery coke ovens – In the non-recovery coke ovens, volatiles evolved during coal carbonization are not recovered as by-products but are combusted in the oven itself in the presence of controlled quantity of air and the heat of the volatiles of evolving gases is utilized for coking of the coal mass into coke and hence no external heating is needed. The heat is generated by the combustion of volatile matter which is then penetrated into the coal mass through radiation from the oven top and also by conduction. The higher level of heat importantly is used to break up the potentially polluting hydro-carbons into the constituent combustible compounds and to burn them hence avoiding the potentially hazardous pollution. The heat consequent to combustion is only partially utilized during the process and the balance heat in the waste flue gas is recovered for energy generation. The key elements of the non-recovery coke oven technology are (i) coke is produced by heating coal, in a controlled atmosphere, thus liberating volatile matter (gas and moisture), (ii) the gas is combusted in an environmentally ‘smart’ way so as to produce the heat to make the coke, (iii) excess heat which is produced in the process is used to generate electricity, (iv) the process does not rely on the combustion of coal, only the gas liberated from the coal, (v) the greenhouse gas emissions of the process are typical of a simple gas fired power generator, that is, one which raises steam that passes through a turbine. Non-recovery coke ovens produce a quality coke for blast furnaces, cupolas, and ferroalloy furnaces etc. These ovens are useful to get high quality coke for blast furnace operation with high pulverized coal injection, where better properties of coke are needed, or to obtain standard quality based on blends with some proportion of non-coking coals.
Non-regulatory instruments – These are performance-based tools which promote improvement through incentives. Their goal is to move ‘beyond compliance’ and to foster continuous improvement by creating the flexibility for parties to innovate. Non regulatory tools include economic instruments (e.g., financial incentives), cooperative management agreements, and voluntary stewardship.
Non-renewable energy – It is the energy derived from finite resources which are consumed much faster than they can be replenished, meaning they are going to eventually run out. These sources, which include fossil fuels like coal, oil, and natural gas, as well as nuclear energy, have been formed over millions of years. Because of their limited supply and negative environmental impact, there is a global shift towards renewable energy alternatives.
Non-renewable resources – These are also called finite resources. These are natural resources which cannot be readily replaced by natural means at a pace quick enough to keep up with consumption. An example is carbon-based fossil fuels. The original organic matter, with the aid of heat and pressure, becomes a fuel such as coal, oil or gas. Other examples for non-renewable resources are minerals and metal ores.
Non-resettable counter – It is a counter within a conveyor system which is resistant to manual resetting, offering precise and tamper-proof tracking of specific events or quantities. Systematic monitoring is necessary for dependable data acquisition.
Non-residential building – It is a structure not primarily used for human habitation, such as offices, and factories etc. These buildings are used for commercial, industrial, institutional, or other non-dwelling purposes, including warehousing. Key characteristics are that they are not designed for living quarters, or any portion of the floor area is not used for dwelling purposes.
Non-return valve – A non-return valve is a single-way valve which allows the fluid to flow only in one direction. The main importance of non-return valves is their working of allowing flow in the downstream direction and preventing the flow in the upstream direction.
Non-rising stem valve – It is a gate valve having its stem threaded into the gate. As the stem turns, the gate moves but the stem does not rise. In this valve, stem threads are exposed to line fluids.
Non-saline water – It is the water with less than 4,000 milligrams per litre of total dissolved solids. It is frequently referred to as fresh water.
Non-slip pulley lagging – It is a layer of material applied to pulley surfaces to amplify grip and diminish slipping with the conveyor belt. Regular inspections are vital to preserve the efficacy of non-slip pulley lagging.
Non-soap grease – It is a grease made with a thickener other than soap, such as clay or asbestos.
Non-solvent – It is a liquid which does not dissolve a given substance, such as a specific polymer. It is the opposite of a solvent, which is a substance that can dissolve another substance. The effectiveness of a non-solvent is relative to the specific solute and conditions, and it can be used in processes like crystallization, where a solvent and non-solvent mixture is used to cause a substance to precipitate out of solution.
Non-spherical nano-particles – These are nano-scale particles which are not in the shape of a sphere, but can have shapes like rods, cubes, prisms, and stars. These shapes give them unique, anisotropic properties which depend on their geometry, allowing them to be tailored for specific applications like advanced electronics, and improved optical devices. Unlike their spherical counter-parts, their asymmetric shape leads to distinct physical and chemical properties.
Non-stationary process – It is a time series where the statistical properties, such as the mean and variance, are not constant over time. This time-dependent nature means that a non-stationary series has characteristics like trends, cycles, or random walks, and its future behaviour cannot be reliably predicted using a single model since the underlying data-generating process changes.
Non-stoichiometric compounds – These are chemical compounds, almost always solid inorganic compounds, having elemental composition whose proportions cannot be represented by a ratio of small natural numbers (i.e. an empirical formula). Very frequently, in such materials, some small percentages of atoms are missing or too many atoms are packed into an otherwise perfect lattice work. Contrary to earlier definitions, modern understanding of non-stoichiometric compounds, view them as homogeneous, and not mixtures of stoichiometric chemical compounds.
Non-stoichiometry – It is a characteristic of a chemical compound where the elemental ratio cannot be expressed as a ratio of small whole numbers, deviating from the ideal chemical formula. This occurs because of the defects in the crystal lattice, such as missing atoms or extra atoms, which can lead to a variable composition rather than a fixed, precise one.
Non-structural adhesive – It is an adhesive which is not needed to support substantial loads but is used to hold lightweight materials in place, frequently referred to as a ‘holding adhesive’. Examples are pressure-sensitive tapes and packaging adhesives.
Non-structural member – It is a building component which is not part of the main load-bearing structure, meaning it does not carry gravity or lateral loads. Examples include architectural partitions, ceilings, windows, piping, mechanical equipment like HVAC (heating, ventilation, and air conditioning) systems, and electrical wiring.
Non-technical aspect – It refers to any aspect of a situation, project, or job which does not need specialized knowledge, skills, or terminology from a particular industrial field. This can include soft skills like communication and teamwork, as well as other factors like regulations, user experience, and ethical considerations.
Non-technical skills – These are also known as soft skills. These are personal attributes and inter-personal abilities which complement technical expertise, enabling people to work effectively with others and manage their tasks efficiently. These skills, such as communication, leadership, and problem-solving, are developed over time through experience and personal growth, rather than formal training, and contribute to a positive and productive work environment.
Non-toxic materials – These are those materials which do not contain substances that are harmful, poisonous, or destructive.
Non-transferred arc (plasma arc welding and cutting, and plasma spraying) – It is an arc established between the electrode and the constricting nozzle. The work-piece is not in the electrical circuit.
Non-uniformity – It is the quality of being inconsistent or lacking uniformity in parts or areas. It describes a situation where something is not the same, or is inconsistent, across its entirety, whether in terms of thickness, temperature, pressure, or other qualities.
Non-uniform properties – These mean that a characteristic, such as a mixture’s composition or an object’s motion, varies across different parts of the system or over time. For a mixture, this means some regions have different components than others. For an object’s motion, it signifies a changing velocity, resulting in unequal distances covered in equal time intervals and a non-zero acceleration.
Non-uniform quality – It is the presence of inconsistency or variation in the characteristics, nature, or performance of a product, material, or system across different parts or at different points in time or space. It means the quality is not the same throughout, leading to differences in aspects like thickness, temperature, concentration, or even the way a task is performed.
Non-uniform quenching – It is perhaps the greatest contributor to the quench cracking. Quench non uniformity can arise from non-uniform flow fields around the part surface during the quench or non-uniform wetting of the surface. Both lead to non-uniform heat transfer during quenching. Non-uniform quenching creates large thermal gradients between the core and the surface of the part.
Non-uniform reduction in cross-section – In this case, the reduction in the thickness direction is not uniform. The material (i) is elongated in the rolling direction, (ii) is spread in the width direction, and (iii) is reduced non-uniformly in the thickness direction. Along the width, material flow occurs only toward the edges of the section. The rolling of an oval section in rod rolling or of an airfoil section is considered to be in this category. In case of highly non-uniform reduction in cross-section, the reduction in the thickness direction is highly non-uniform. A portion of the rolled section is reduced in thickness, while other portions can be extruded or increased in thickness. As a result, in the width (lateral) direction material flow can be toward the centre. Of course, in addition, the material flow takes place in the thickness direction as well as in the rolling (longitudinal) direction.
Non-value-added analysis – Activities which are non-value-added result in profitless expense of time, money, and resources and add unnecessary cost to the products. The non-value-added analysis identifies activities which can be eliminated with no deterioration of the organizational performance (cost, function, quality, and perceived value). Non-value-added analysis highlights wasteful activities.
Non-volatile substance – It is a substance which does not easily evaporate into a gas under normal conditions. It has a low vapour pressure and a high boiling point. Unlike volatile substances, such as alcohol or gasoline, which readily transform into vapour, non-volatile materials, like salt, do not quickly convert to gas and are normally not easily smelled.
Non-wetting liquids – These are the liquids in which the cohesive forces are dominant rather than adhesive forces. These liquids have very high contact angle.
Non-woven fabric – It is a planar textile structure produced by loosely compressing together fibres, yarns, rovings, and so on, with or without a scrim cloth carrier. It is accomplished by mechanical, chemical, thermal, or solvent means, and combinations thereof.
Non-zero coefficient – It is a coefficient (a numerical value) in an equation or polynomial which is not equal to zero. In the context of regression, a non-zero coefficient indicates a relationship exists between the independent and dependent variables. For a polynomial to be non-zero, at least one of its coefficients is to be non-zero, meaning the polynomial is not the zero polynomial, which is defined as all coefficients being zero.
No objection certificate (NOC) – It is a type of legal certificate issued by any agency, organization, institute or, in certain cases, an individual.
Norm – It can be defined as sets of relations that define forms of communicating, feeling, acting, and thinking. Norms define what is allowed and what is not allowed to be said, felt, done, or thought. They are situational and relationally negotiated. Normally described in terms of their functions (descriptive, constitutive, prescriptive), the term commonly designates prescriptive guides. Norms can be more or less explicit, more or less prescriptive, and be more or less opposed and resisted. Although sometimes viewed as limiting possibilities rather than creating them, they can be seen as producing a certain set of possibilities and transformed through people’s engagement with them in their relations to others.
Normal – It is an imaginary line forming right angles with a surface or other lines sometimes called the perpendicular. It is used as a basis for determining angles of incidence, reflection, and refraction.
Normal anisotropy – It refers to the property of a material where its mechanical properties, such as tensile strength or ductility, vary depending on the direction in which they are measured. This difference in properties arises from the material’s internal structure, particularly its crystalline or grain orientation, and is frequently observed in rolled or extruded metal sheets.
Normal boiling point – It is the temperature at which a liquid turns into a gas when the external pressure is exactly one atmosphere. This is a specific and standardized boiling point, defined at standard sea level pressure, where 1 atmosphere is equivalent to 101.325 kilopascals or 760 millimeters of mercury.
Normal continuous load – It means that the given load current is going to flow continuously through cable. Standards are to be referred for current ratings for poly vinyl chloride (PVC) cables which are based on the normal conditions of installation. If the actual conditions are not the same as the normal conditions, the values for the normal current ratings are to be multiplied by the relevant rating factors as given in the standards.
Normal direction – It is that direction which is perpendicular to the plane of working in a worked material.
Normal distribution – It is the probability density function which is used to describe the mechanical properties of materials and the distribution of most random variables encountered in engineering design. In statistical analysis, normal distribution is a continuous distribution which was first studied in connection with errors of measurement and, hence, referred to as the normal curve of errors. The normal distribution forms the cornerstone of a substantial portion of statistical theory. The normal distribution is used to model some continuous variables. It is a symmetrical bell-shaped curve which is completely determined by two parameters. They are the distribution (or population) mean, ‘ mu’, and the standard deviation, ‘sigma’. Hence, once the mean and standard deviation are provided, it is possible to calculate any percentile (or risk) of the distribution. It is a population distribution which is symmetric and for which 68 % of the cases are within one standard deviation of the mean, 95 % of the cases are within two standard deviations of the mean, and around all the cases are within three standard deviations of the mean. This is the origin of the ’70 %, 95 %, 100 % rule of thumb’ which is used to help interpretation of the sample standard deviation, ‘sigma’. The real reason that the sample mean, ‘mu’ and sample standard deviation, ‘sigma’, are so important is since as well as being simple summaries of average and spread, they can also be used to estimate the parameters of the normal distribution. In addition, the central-limit theorem justifies the use of the methods of inference developed for data from a normal model (and hence also the use of the sample ‘mean’ and standard deviation), even when the raw data are not normally distributed. Certain sample statistics have a normal sampling distribution. Normal distribution is also called the Gaussian distribution. The normal distribution has the two parameters mu and sigma. When mu = 0 and sigma = 1 it is said to be in its standard form, and it is referred to as the standard normal distribution. The normal distribution is characterized by its symmetric shape and bell-shaped appearance.
Normal distribution curve – It is also known as a bell curve or Gaussian distribution. It is a symmetrical, bell-shaped graph which shows the distribution of data where most values cluster around a central mean. The mean, median, and mode are all equal and at the peak of the curve, with the data points tapering off symmetrically on either side. It is defined by its mean (mu) and standard deviation (sigma), which determines the curve’s spread.
Normal force – In tribology, it is the force This applied normal to the surface of one body by another contacting body or bodies. term is more precise and hence preferred. However, the term normal load is also in use. If applied vertically, the load can be expressed in mass units, but it is preferable to use force units such as newtons (N).
Normal hydrogen electrode (NHE) – It is also known as the standard hydrogen electrode (SHE). It is a reference electrode used in electro-chemistry to measure the potential of other half-cells. It consists of a platinum electrode coated with platinum black, immersed in a solution of 1M hydrogen ions (H+) at a constant temperature of 298 K, with hydrogen gas at 100 kilo-pascals pressure bubbled over it. Its electrode potential is defined as exactly zero volts under these standard conditions, making it the universal zero point for measuring electrode potentials.
Normality – It is a measure of the number of gram-equivalent weights of a compound per litre of solution. It is defined as the number of gram or mole equivalents of solute present in one litre of solution. The SI (International System of Units) unit of normality is equivalents per litre (Eq/L). Normality is given by the equation N = Msol / (EWsol + Vsol), where ‘N’ is normality, ‘Msol’ is the mass of solute in grams, ‘EWsol’ is the equivalent weight of solute, and ‘Vsol’ is the volume of the entire solution in litres.
Normality, costs – As per this classification, costs can be either normal costs or abnormal costs. Normal costs arise during routine day-to-day operations in the organization. Abnormal costs arise because of those abnormal activities which are not part of normal or routine operations. Example of such costs the costs arising out of accidents or serious equipment breakdown etc.
Normalization – It is the process of bringing or returning something to a normal condition or state. In case of data management, normalization is the process of organizing data within a database to reduce redundancy and improve data integrity. It involves breaking down large tables into smaller, more manageable ones and establishing relationships between them. This process helps to eliminate data anomalies and inconsistencies, leading to a more efficient and reliable database system. In heat treatment, normalization is a process of heating metal, typically steel, to a specific temperature above its critical point, holding it there, and then cooling it in still air. This process refines the metal’s grain structure, relieves internal stresses, and improves mechanical properties like hardness and strength. It is a relatively quick and cost-effective way to enhance a material’s ductility, toughness, and machinability.
Normalization strategy – It is a systematic plan for organizing data to reduce redundancy and improve data integrity, consistency, and efficiency. It involves applying a series of formal rules, known as normal forms, to decompose large, complex tables into smaller, more manageable ones. A sound strategy helps prevent issues called data anomalies, which can lead to inconsistencies when data is inserted, updated, or deleted.
Normalized cut-off frequency – It is the ratio of the actual cut-off frequency to the Nyquist frequency, which is half the sampling frequency. This is a normal practice in digital signal processing to express frequencies on a scale where the Nyquist frequency is defined as 1. This allows designers to define filter parameters independent of the specific sampling rate.
Normalized erosion resistance – It is the volume loss rate of a specified reference material divided by the volume loss rate of a test material got under similar testing and analysis conditions. ‘Similar testing and analysis conditions’ means that the volume loss rates of the two materials are determined at the corresponding portions of the erosion rate-time pattern, for example, the maximum erosion rate or the terminal erosion rate. A desired complete wording has the form, ‘the normalized erosion resistance of (test material) relative to the (reference material) based on (criterion of data analysis) is (numerical value)’.
Normalized power spectrum – It is a representation of a signal’s power distribution across different frequencies, where the total power is scaled to a specific value, typically 1. This normalization makes it possible to compare the relative distribution of power at each frequency, regardless of the total signal energy. For example, it is got by dividing the power spectral density by its maximum value or its total energy, making it useful for applications like signal processing and statistical analysis.
Normalizing – Normalizing treatment is frequently applied to the steel in order for the achievement of any one or more of these objectives, namely (i) to refine the grain structure, (ii) to obtain uniform structure, (iii) to decrease residual stresses, and (iv) to improve the machinability of the steel. Normalizing is a process in which steel is heated, to a temperature above the A3 temperature or the Acm temperatures and then cooled in atmospheric air. The purpose of the normalizing treatment is to remove the effects of any previous heat treatment (including the coarse-grained structure sometimes resulting from high forging temperatures) or cold-working. The normalizing process is done to ensure a homogeneous austenite on reheating for hardening or full annealing. The resultant structures are pearlite or pearlite with excess ferrite or cementite, depending upon the composition of the steel. The structures after normalizing are different from the structures resulting after annealing and the steels of the same carbon content in the hypo-eutectoid or hyper-eutectoid ranges, there is less excess ferrite or cementite and the pearlite is finer. These are the results of the more rapid cooling. Since the type of structure, and, hence, the mechanical properties, are affected by the rate of cooling, substantial variations can take place in normalized steels because of differences in section thickness of the shapes being normalized.
Normal load – In tribology, it is the force applied normal to the surface of one body by another contacting body or bodies. However, the term normal force is more precise and hence preferred. If applied vertically, the load can be expressed in mass units, but it is preferable to use force units such as newtons (N).
Normally-closed valve – It is a condition wherein the valve closure member moves to a closed position when the actuating energy source fails.
Normally closed solenoid valve – It is an electrically operated valve whose inlet orifice is closed when the solenoid coil is not energized. It is to be energized to open.
Normally-open valve – It is a condition wherein the valve closure member moves to an open position when the actuating energy source fails.
Normally open solenoid valve – It is an electrically operated valve whose inlet orifice is open when the solenoid coil is not energized. The valve is to be energized to close.
Normal operating load – It is the set of forces, stresses, or pressures a system, structure, or component is expected to handle during its standard, everyday functioning. It differs from the design load, which includes maximum anticipated loads and safety margins for extreme conditions. Normal operating load encompasses typical forces like weight, pressure, thermal expansion, and the electrical power consumed by connected devices.
Normal operating range – It refers to the typical range of values for a process parameter where a process is expected to operate consistently, producing acceptable quality output. It represents the normal variability of a process that is not easily controlled, but it is not intended to introduce flexibility in manufacturing conditions. Instead, it helps define the practical limits of what is achievable in a real-world manufacturing setting.
Normal operating region – It is the typical range of values for a process or system’s variables where it functions smoothly, safely, and efficiently. This region allows for natural variations and fluctuations without causing equipment failure or performance issues. As an example, a temperature control system might have a normal operating region of 35 deg C +/- 5 deg C, meaning it is expected to operate within this range despite small, inherent variations.
Normal operation – It refers to the standard, expected, and intended functionality of a system, device, or process, working as designed without errors or malfunctions. This includes operating within specified parameters and limits, performing its designed activities smoothly and effectively, and excluding abnormal periods like start-up, shutdown, or malfunctions.
Normal-phase chromatography (NPC) – It refers to liquid-solid chromatography or to bonded-phase chromatography with a polar stationary phase and a non-polar mobile phase.
Normal pressure force – It refers to the force exerted by a fluid on the surface of an immersed body when the fluid is stationary, acting perpendicular to the surface. This pressure contributes to the overall drag experienced by the body in a fluid flow.
Normal segregation – It is a critical phenomenon in metallurgy which affects the quality and properties of metal alloys. It refers to the uneven distribution of alloying elements or impurities during the solidification process, resulting in a non-uniform composition throughout the casting. It occurs when the solidifying alloy rejects certain elements or impurities into the remaining liquid, causing a concentration gradient. This gradient can lead to variations in the microstructure, mechanical properties, and corrosion resistance of the final product. The main causes of normal segregation are (i) differences in the solubility of elements in the solid and liquid phases, (ii) variations in the cooling rate and solidification time, and (iii) presence of impurities or inclusions. Normal segregation results into concentration of alloying constituents which have low melting points in those portions of a casting which solidify last.
Normal solution – It is an aqueous solution containing one gram equivalent of the active reagent in 1 litre of the solution.
Normal strain – It occurs when the elongation of an object is in response to a normal stress (i.e., perpendicular to a surface), and is denoted by the Greek letter epsilon. A positive value corresponds to a tensile strain, while negative is compressive.
Normal strength – It is the strength of a material which is its ability to withstand an applied load without failure or plastic deformation.
Normal stress – It is the stress component which is perpendicular to the plane on which the forces act. Normal stress can be either tensile or compressive.
Normal temperature and pressure (NTP) – NTP means a temperature of 20 deg C (293.15 K) and an absolute pressure of 1 atmosphere (101.325 kilo-pascal, kPa).
Normal wear – It is the loss of material within the design limits expected for the specific intended application. The concept of normal wear depends on economic factors, such as the expendability of a worn part.
Normal wear and tear – It refer to the natural and gradual deterioration of property or equipment due to regular use over time. It is the expected depreciation which happens even with proper care and maintenance, distinct from damage caused by negligence, misuse, or an accident.
Normative commitment dimension – It is the third and the last dimension of the organizational commitment mode. Meyer and Allen define normative commitment as ‘a feeling of obligation to continue employment’. Internalized normative beliefs of duty and obligation make individuals obliged to sustain membership in the organization. As per Meyer and Allen ‘employees with normative commitment feel that they ought to remain with the organization’. In terms of the normative dimension, the employees stay since they are to do so or it is the proper thing to do. It has been found that employee commitment goes up when they feel affiliation with the organization and also when organization recognizes them as a part of organization. Recognition as a part of organizational success story increases the commitment level and also the individual and organizational productivity.
Normative part – It is a section which contains mandatory requirements and prescriptive statements, establishing a standard of what is to be done to be considered correct or compliant. In engineering or standards, this is a rule which is to be followed to claim conformity. In other fields, it defines what is considered good, desirable, or correct behaviour, frequently involving value judgments, as opposed to just describing how things are (a descriptive statement).
Normative reference – It is a document or standard which is necessary and indispensable for the application of another, main standard. These references are incorporated by reference and provide specific requirements, definitions, methodologies, or other details needed to fully implement the main standard. For a product or system to comply with the main standard, it is also to comply with its normative references.
North pole – It is the northern-most point on earth, located at the northern end of the planet’s axis of rotation. It is a specific point where all lines of longitude converge, situated in the middle of the Arctic Ocean, and is covered by a shifting layer of sea ice. The geographic north pole is not to be confused with the magnetic north pole, which is a separate, shifting location that a compass needle points to. In a magnet, it is the end that points toward the earth’s geographic north when the magnet is freely suspended, which is why it is also called the ‘north-seeking’ pole. Despite its name, this pole is attracted to the earth’s magnetic pole located near the geographic north pole, meaning it is actually a south magnetic pole.
Norton circuit – It is a simplified equivalent circuit of a complex linear electrical network that consists of a single current source (IN) in parallel with a single resistor (RN). This simplified representation behaves identically to the original circuit at its terminals, allowing for easier analysis by replacing any complex circuit with a single, two-terminal component.
Norton creep equation – It is also known as Norton’s law. It is a constitutive equation which describes the steady-state creep behaviour of materials, particularly in the secondary creep regime. It relates the creep strain rate to the applied stress, frequently following a power law relationship.
Norton equivalent circuit – It is a simplified two-terminal model of a complex linear electrical circuit, consisting of a single current source (IN) in parallel with a single Norton resistance (RN). This equivalent circuit is used to analyze a complex network by replacing it with these two components, where IN is the current which is flow through a short circuit across the terminals and RN is the equivalent resistance seen looking into the circuit with all independent sources turned off.
Norton’s theorem – it is a theorem which states that any network of current sources, voltage sources, and resistors can be simplified to an equivalent network with only a current source and shunt admittance. It is the dual of Thevenin’s theorem.
Nose bar transfer – It is a conveyor system design incorporating a nose bar to facilitate the seamless transfer of materials between conveyors. Periodic checks are requisite for ensuring proper alignment and efficient material transfer.
Nose-over – It is a segment of the conveyor equipped with transition rollers for ensuring a smooth transition from incline to horizontal or vice versa. Periodic inspections are necessary for sustaining proper functionality and optimal material flow.
Nose radius – It is the radius of the rounded portion of the cutting edge of a tool.
Nose roller – It is a diminutive roller used on power belt curve conveyors to minimize gaps at transfer points. Regular inspections are indispensable to uphold the effective functionality of the nose roller.
No-slip condition – It is a fundamental principle in fluid dynamics which states that a viscous fluid touching a solid surface has zero relative velocity to that surface. This means the fluid ‘sticks’ to the boundary, and its velocity at the interface is equal to the velocity of the solid surface, which is frequently zero. This phenomenon is a direct result of fluid viscosity.
Not applicable – It means that a statement, question, or field is irrelevant or does not apply to a particular situation or person. It is normally abbreviated as N/A and is used on forms or in official documents to indicate that a specific piece of information is not relevant for the respondent or the task at hand.
Notch – It refers to a V-shaped, U-shaped, or semi-circular defect deliberately introduced into a planar material. In structural components, a notch causes a stress concentration which can result in the initiation and growth of fatigue cracks. Notches are used in materials characterization to determine fracture mechanics related properties such as fracture toughness and rates of fatigue crack growth.
Notch acuity – It relates to the severity of the stress concentration produced by a given notch in a particular structure. If the depth of the notch is very small compared with the width (or diameter) of the narrowest cross section, acuity can be expressed as the ratio of the notch depth to the notch root radius. Otherwise, acuity is defined as the ratio of one-half the width (or diameter) of the narrowest cross-section to the notch root radius.
Notch bar – It is small size ingot with notches to facilitate breakage for remelting.
Notch brittleness – It is the susceptibility of a material to brittle fracture at points of stress concentration. For example, in a notch tensile test, the material is said to be notch brittle if the notch strength is less than the tensile strength of an unnotched sample. Otherwise, it is said to be notch ductile.
Notch depth – It is the distance from the surface of a test sample to the bottom of the notch. In a cylindrical test sample, it is the percentage of the original cross-sectional area removed by machining an annular groove.
Notch, double shear – It is an abrupt deviation from straight on a sheared edge. This offset can occur if the flat sheet or plate product is longer than the blade for the final shearing operation.
Notch ductility – It is the percentage reduction in area after complete separation of the metal in a tensile test of a notched sample.
Notched bar – It is a test sample which is notched. It is used in impact test or fatigue test.
Notched bar impact test– It this test, a one-time force with a large load is applied to the metal sample, resulting in multiaxial stresses. Tests are performed at high or low temperatures. The objective of the test is to accurately predict the probability of a brittle fracture.
Notched-bar upset test – It is similar to the conventional upset test, except that axial notches are machined into the test samples. The notched-bar test is used with materials of marginal forgeability for which the standard upset test can indicate an erroneously high degree of workability.
Notched belt – It is a conveyor belt featuring notches or cutouts to accommodate specific product shapes. Regular inspections are imperative to ascertain the integrity of the notched belt.
Notched impact testing – Ferritic steels, with their body-centered cubic (bcc) structure, have the disadvantage of breaking in a brittle fashion at low temperatures. This means, in terms of the ideas of the tensile test that the % elongation at failure is close to zero. As the temperature is lowered, there is a small temperature range over which the steels with bcc structure suddenly begin to fail in the brittle mode. An average temperature of the small range, called the ‘ductile brittle transition temperature’ (DBTT), is often chosen to characterize the temperature where the transition occurs. The simple tensile test detects this transition, but unfortunately, it detects DBTT values well below those that occur in complex steel parts. The tensile test applies stress in only one direction while in complex steel parts, the applied stress acts in all three possible directions, a situation called a tri-axial stress state. The DBTT is raised by a tri-axial stress state. A tri-axial stress state develops at the base of a notch when a notched sample is broken in a tensile machine, and such tests are called notched tensile tests. However, it is more useful to break the sample with an impact test, where the load is applied much more rapidly than in a tensile machine, since the combination of the notch geometry and the high load rate produce values of DBTT close to the temperature where brittle failure begins to occur in complex steel parts.
Notched plate – It is a structural component with a deliberately cut notch, used in engineering to study stress concentration, fatigue, and fracture toughness. It can also refer to a metallic plate with a V-shaped or rectangular opening used to measure the flow rate of a liquid.
Notched sample – It is a test sample which has been deliberately cut or notched, normally in a V-shape, to induce and locate point of failure.
Notch factor – It is the ratio of the resilience determined on a plain sample to the resilience determined on a notched sample.
Notch fatigue – It is the phenomenon where the presence of a ‘notch’ (such as a sharp corner, hole, or other geometric irregularity) in a component considerably reduces its fatigue strength and durability under cyclic loading. This occurs since the notches act as stress concentration points, causing stress to build up locally and making the material more likely to crack and eventually fail under repeated stress cycles.
Notch filter – It is a filter with a narrow reject band which is used to block, for example, a pilot tone out of a communications network.
Notching – It consists of cutting out different shapes from the edge of a strip, blank, or part. Notching is also a vibration testing control technique engineers can use to limit vibration at an input response channel to prevent over-testing or potential damage.
Notching press – It is a mechanical press which is used for notching internal and external circumferences and also for notching along a straight line. These presses are equipped with automatic feeds since only one notch is made per stroke.
Notch root – It is the critical, V-shaped or U-shaped area at the bottom of a notch where stress is concentrated. This concentration can lead to localized plastic deformation and is a key factor in determining a material’s resistance to fracture and fatigue failure. It is where the highest stress is experienced in a notched component.
Notch rupture strength – It is the ratio of applied load to original area of the minimum cross section in a stress-rupture test of a notched sample.
Notch sensitivity – It is the extent to which the sensitivity of a material to fracture is increased by the presence of a stress concentration, such as a notch, a sudden change in cross section, a crack, or a scratch. Low notch sensitivity is normally associated with ductile materials, and high notch sensitivity is normally associated with brittle materials.
Notch strength – It is the maximum load on a notched tensile-test sample divided by the minimum cross-sectional area (the area at the root of the notch). It is also known as notch tensile strength.
Notch-strength ratio – It is the ratio of notch-tensile strength to tensile strength of the material. This provides a measure of tensile efficiency for the specific design of notch. It is not consistently reliable as a measure of notch toughness.
Notch tensile strength (NTS) – Notch tensile strength of a material is the value given by performing a standard tensile strength test on a notched sample of the material. The ratio between the notch tensile strength and the tensile strength is called the notch strength ratio (NSR).
Notch tensile test – It uses a notched sample. This test aims to measure the resistance of planar sample with uniform thickness and sharp notch(es) to a slow crack growth, under boundary conditions of constant or accelerated loading rates.
Notch toughness – It is measured normally in terms of the absorbed impact energy needed to cause fracturing of the sample. The change in potential energy of the impacting head (from before impact to after fracture) is determined with a calibrated dial that measures the total energy absorbed in breaking the sample. Other quantitative parameters, such as fracture appearance (percent fibrous fracture) and degree of ductility / deformation (lateral expansion or notch root contraction), are also frequently measured in addition to the fracture energy. Impact tests can also be instrumented to obtain load data as a function of time during the fracture event. In its simplest form, instrumented impact testing involves the placement of a strain gauge on the tup (the striker).
Notch-yield ratio – It is the ratio of notch-tensile strength to tensile yield strength of the material. This provides a measure of notch toughness and, hence, of the inverse of notch sensitivity. Notch-yield ratio is considered to be a more useful measure of notch toughness than notch-strength ratio since it provides a relative measure of the ability of a material to plastically deform locally in the presence of a stress-raiser and hence to redistribute the stress.
Note – It is a brief record of something written down to assist the memory or for future reference. It is also a commentary or reference appended to a text.
Notice inviting tender (NIT) – It is published by the organizations to get biddings from the contractors for the proposed works. It means this document and its annexures, any corrigendum, addendum, and any other documents provided along with this notice inviting tender or issued during the selection of the bidder, seeking a set of solution(s), services(s), materials and / or any combination of them.
Not to scale (NTS) – It indicates that a drawing, or a portion of it, is not drawn to a specific proportional size relative to the actual object it represents. This abbreviation is normally used on preliminary drawings, sketches, or details where precise measurements are not critical or where it is impractical to maintain a consistent scale.
No-twist block – It is also known as no-twist mill. In wire rod mills, it represents one of the key elements. Only through this development, it has become possible to safely roll thin wire rods at speed of over 120 meters per second. The no twist blocks can be of 4, 6, 8, and 10 roll stands for twist free rolling. A primary gearbox drives the roll units through two common shafts. No-twist blocks having two different sizes of roll units are available, with 170 millimeters / 150 millimeters diameter rolls and 225/200 millimeters diameter rolls. All roll units are identical and inter-changeable. The advantages of the no-twist blocks are (i) ultra heavy-duty housings, (ii) low ring changing time, (iii) negligible spring action, (iv) reduced maintenance, (v) simpler section control, remote adjustments under load, and (vi) flexibility of rolling of different wire rod grades.
Novaculite – It is also called Arkansas stone. It is a micro-crystalline to crypto-crystalline rock type which consists of silica in the form of chert or flint. It is normally white to grey or black in colour, with a specific gravity which ranges from 2.2 to 2.5. It is used in the production of sharpening stones. It is known for its use as a whetstone because of its fine texture and hardness. The name ‘novaculite’ comes from the Latin word novacula, meaning ‘razor’ or ‘sharp knife’, reflecting its main application in sharpening stones.
Novolac – It is a linear, thermoplastic, B-staged phenolic resin, which, in the presence of methylene or other cross-linking groups, reacts to form a thermoset phenolic. It is a type of thermoplastic phenolic resin created by the acid-catalyzed condensation of phenol with formaldehyde under conditions of excess phenol, resulting in a linear polymer structure. It is a key precursor to the thermosetting plastic Bakelite, where novolac is heated with more formaldehyde to form a rigid, infusible, three-dimensional cross-linked network. Novolacs and their derived epoxy resins are used in high-performance applications, such as chemical-resistant coatings for industrial floors, composite materials, and foundry mould binders because of their excellent chemical and thermal stability.
Novolac phenolic adhesives – These are acid-catalyzed phenol-formaldehyde resins which are thermo-plastic and need a separate curing agent, such as hexamethylene tetramine, to become a strong, thermoset material. They differ from resole resins by using an excess of phenol over formaldehyde during synthesis and need a hardener to form a cross-linked network, providing high thermal stability, chemical resistance, and mechanical strength for applications like composite materials and high-temperature binders.
Novolac resin – It is a linear phenol-formaldehyde polymer, produced using an acid catalyst and an excess of phenol over formaldehyde. It is a thermoplastic polymer with a limited degree of polymerization, needing a separate curing agent, such as hexamine, to form a cross-linked, infusible, and thermosetting material.
Nowel – It is the core of a mould for casting a large hollow object. It is also the bottom part of a mould or of a flask, in distinction from the cope.
NOx conversion – It refers to the process of reducing nitrogen oxides (NOx) emissions, typically through selective catalytic reduction (SCR) or other catalytic methods, which need a reducing atmosphere and frequently involve the addition of hydro-carbons or reducing agents like ammonia to achieve substantial conversion efficiencies.
Noxious gases -These are harmful or poisonous gases which can be deadly if inhaled. They can build up in confined spaces, such as factories, and can be caused by certain activities like welding. Examples of noxious gases are carbon mono-oxide, and fumes from certain industrial activities.
NOx removal process – It converts harmful nitrogen oxides (NOx) in flue gas into harmless substances, mainly nitrogen gas (N2) and water (H2O), through chemical reactions, frequently using catalysts and reducing agents like ammonia or urea. These processes use methods such as ‘selective catalytic reduction’ (SCR), which uses catalysts to facilitate the reaction, and non-catalytic methods at high temperatures or by using absorbents and reducing agents like hydrogen peroxide.
Nozzle – It is a device designed to control the direction or characteristics of a fluid flow (specially to increase velocity) as it exits (or enters) an enclosed chamber or pipe. A nozzle is frequently a pipe or tube of varying cross-sectional area, and it can be used to direct or modify the flow of a fluid (liquid or gas). Nozzles are frequently used to control the rate of flow, speed, direction, mass, shape, and / or the pressure of the stream that emerges from them. In a nozzle, the velocity of fluid increases at the expense of its pressure energy. In case of welding, nozzle is a device which directs shielding media. It is also a device within a conveyor system which releases air or other substances for diverse purposes, such as cleaning or cooling. Regular checks are vital to guarantee optimal nozzle performance and prevent potential clogs.
Nozzle, air mist – The essential features of the air mist nozzles are the mixing chamber, extension pipe, water and air inlet adapters and their internal geometries, and geometry of nozzle tip. These components are to be precision designed to ensure a very high heat transfer coefficient, stable spray angles and uniform water distribution. The air mist nozzles have non clogging characteristics and there are no wear parts in the mixing chamber of air and water. The spray width of these nozzles is stable within a wide range of water pressure. Hence, these nozzles have constant and uniform spray characteristics. Air mist nozzle is to meet the requirements of (i) atomization of cooling water into a fine mist for uniform cooling of the steel, (ii) wide angle discharge of the mist stream in order to reduce the installation of number of nozzles, (iii) increase in the size of the nozzle outlet to have reduction in the nozzle clogging and increase in the discharged water volume range, and (iv) the nozzle size is to facilitate its installation between the rolls.
Nozzle brick – It is a thick-walled tubular refractory shape set in bottom of a ladle through which steel is teemed.
Nozzle clogging – Clogging in continuous casting nozzles is the build-up of material in the flow passage between the tundish and mould. The nozzle clogging phenomenon has been one of the most disruptive problems for the continuous casting process as long as the casting machines have been operating. This phenomenon produces an inconsistent flow and temperature variations, steel level fluctuations in the mould, impairment of steel quality, and the abrupt interruption of the steel casting. Clogging starts when solid compounds, mainly steel skull, and non-metallic inclusions, are non-uniformly deposited at the inner wall of the submerged entry nozzle (SEN) at some typical preferential zones characterized for neighbouring dead flow conditions. The primary sources of these inclusions are (i) the reaction between the dissolved oxygen with the deoxidizers, (ii) re-oxidation in the tundish or the nozzle, and (iii) the entrainment of slag or refractory particles. The consequences of nozzle clogging include (i) decreased productivity, (ii) increased cost, and (iii) decreased quality. Nozzle clogging is a serious productivity and quality problem in continuous casting.
Nozzle design – It is the engineering process of creating a device which controls the flow of a fluid to modify its velocity, pressure, and direction. This is achieved by carefully shaping the nozzle’s geometry, which can be simple or highly complex, to achieve specific outcomes like optimized spray patterns for cooling or coating. The design process involves applying fluid dynamics principles to manipulate the fluid’s pressure energy into kinetic energy.
Nozzle Expert – It helps to detect clogged nozzles and broken hoses in all types of continuous casting machines, and ensures that the strand is uniformly cooled during the continuous casting process. The steel is cooled by spraying water onto the strand through nozzles.
Nozzle guide vane (NGV) – It is a stationary component in a gas turbine engine which directs and accelerates high-velocity hot gases from the combustion chamber onto the turbine blades. These components are crucial for increasing turbine efficiency by directing the flow of gases and are frequently made of high-temperature-resistant materials.
Nozzle mix combustion – In nozzle mix or non-premixed combustion, fuel and air are completely separate before they reach the burner head. They come into contact and react at the flame formation place. The flame formed by this method is also known as a diffusion flame. This method is used in nozzle mix burners for burning fuel.
Nozzle pocket brick – It is a refractory shape set in bottom of a ladle containing a recess in which nozzle is set.
Nozzle refractory – It is a refractory shape containing an orifice for the purpose of transmitting molten metal from a refractory-lined container.
Nozzle tip – It is the final, frequently interchangeable, component at the end of a nozzle which controls the discharge of a fluid or material. Its shape and size dictate the flow rate, spray pattern, and droplet size, and it is designed to either facilitate or restrict the flow of material, depending on the application. Examples include the tips of sprayers, which atomize liquids, or the tips of injection moulding nozzles, which inject molten plastic into a mould.
NPN transistor – It is a type of bipolar junction transistor (BJT) made of two n-type semiconductor layers with a thin p-type layer in between, creating three terminals namely the emitter, base, and collector. It functions as a switch or an amplifier by using a small current at the base to control a much larger current flowing from the collector to the emitter. This makes NPN transistors very useful for controlling high-power loads with low-power micro-controllers and for signal amplification.
N shell – It is the fourth layer of electrons surrounding the nucleus of an atom, having electrons with the principal quantum number 4.
‘n’th root – ‘n’th root of a number ‘x’ is a number ’r’ (the root) which, when raised to the power of the positive integer ‘n’ yields ‘x’.
NTP – It stands for ‘normal temperature and pressure’, which refers to a set of specific conditions used as a standardized reference point for measuring and reporting the properties of substances, particularly gases. Under NTP conditions, the temperature is typically 0 deg C (273.15 K) and the pressure is 101.325 kilopascals.
N-type doping – It is the process of adding impurities with five valence electrons to a pure semi-conductor to create an excess of free electrons, which are the majority charge carriers. This process, which uses pentavalent ‘donor’ atoms like phosphorus or arsenic, increases the material’s conductivity by providing extra negative charges.
Nuclear – It relates to, or constituting a nucleus. It also relates to, producing, or using energy which is created when the nuclei of atoms are split apart or joined together.
Nuclear accident – Other terms used are nuclear disaster, and radiation accident. It is defined by the International Atomic Energy Agency (IAEA) as ‘an event that has led to significant consequences to people, the environment or the facility’. Examples for nuclear accident are lethal effects to individuals, large radio-activity release to the environment, or a reactor core melt.
Nuclear cermet fuel – Cermet fuels consist of ceramic fuel particles such as uranium di-oxide (UO2) embedded in a metal matrix, which is typically tungsten (W) because of a high melting point and excellent compatibility with hot hydrogen. It is in the form of a sintered fuel rod composed of a fissile carbide or oxide constituent and a metallic matrix.
Nuclear charge – It refers to the total positive charge found in the nucleus of an atom. In the context of transition elements like copper, it plays a significant role in determining the energy levels of orbitals and the hybridization between them.
Nuclear concrete – It is the concrete which is used for the construction of the nuclear island in a nuclear power plant. It is normally the radiation shielding ultra-high-performance concrete (RS-UHPC) which is an advanced type of concrete engineered for optimal packing density to improve mechanical properties and durability while effectively attenuating radiation.
Nuclear cross-section (sigma) – It is the probability that a nuclear reaction is going to occur between a nucleus and a particle, expressed in units of area (normally barns).
Nuclear decay – It is called radio-active decay. It is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is considered radio-active. Three of the most common types of decay are alpha, beta, and gamma decay.
Nuclear energy – It is the energy released by a nuclear reaction (either fission or fusion) or by radio-active decay.
Nuclear engineering – It is the engineering discipline concerned with designing and applying systems which utilize the energy released by nuclear processes. The most prominent application of nuclear engineering is the generation of electricity.
Nuclear facility – It is a site which handles radio-active materials, such as a nuclear reactor, a site for processing nuclear waste, or a facility for enriching uranium. These installations, which are subject to strict safety and security regulations, are designed to convert nuclear energy into heat or electricity, or to process, store, and dispose of radio-active materials.
Nuclear fission -It is a reaction in which the nucleus of an atom splits into two or more smaller nuclei. The fission process frequently produces gamma photons, and releases a very large amount of energy even by the energetic standards of radio-active decay.
Nuclear fuel – It refers to a substance, typically a fissile material, which is used by nuclear power stations or other nuclear devices to generate energy. It is uranium or plutonium which has been fabricated into pins, assemblies, plates, or other such similar form for the purposes of fuelling a nuclear reactor. Other High-Z elements are capable of being used as nuclear fuel (e.g., thorium) normally used for fusion reactors.
Nuclear fuel cycle – It is the sequence of steps involved in supplying, using, and disposing of the fuel used in nuclear reactors. The fuel cycle is ‘closed’ if it includes the reprocessing of spent fuel and recycling of fissile materials resulting from reprocessing. The term ‘open’ or ‘once-through’ cycle means that the fuel is disposed of in a permanent storage site after use in the reactor.
Nuclear fuel manufacture – It is the process of creating a fuel assembly for nuclear reactors, which involves mining uranium ore and converting it into a usable form through purification, enrichment, and fabrication steps. This front end of the nuclear fuel cycle prepares uranium, typically enriching the U-235 isotope to a specific concentration, into small, dense pellets. These pellets are then stacked into long metal tubes (fuel rods) which are grouped into fuel assemblies for use in a reactor.
Nuclear fuel reprocessing – It is the chemical process of separating usable uranium and plutonium from spent nuclear fuel. This is done to recover these fissile materials for reuse, which can reduce the volume of radio-active waste and extend the availability of nuclear fuel resources.
Nuclear fusion – It is a reaction in which two or more atomic nuclei, combine to form one or more atomic nuclei and neutrons. The difference in mass between the reactants and products is manifested as either the release or absorption of energy.
Nuclear fusion reaction – It is a process where two or more light atomic nuclei combine to form a single, heavier nucleus, releasing a massive quantity of energy. This happens at extremely high temperatures and pressures, such as those found in the cores of stars like our sun, where light elements like hydrogen isotopes fuse to form helium. The energy is released since the resulting heavier nucleus is more stable, and a small quantity of mass is converted into energy, as described by Einstein’s equation E =m(c square), where ‘E’ is energy, ‘m’ is mass, and ‘c’ is the speed of light.
Nuclear gamma resonance (NGR) – Nuclear gamma resonance on the resonant emission and absorption of gamma-ray photons by atomic nuclei in a solid. In spite of the large energies of the gamma-rays involved, these processes occur without an energy loss because of the nuclear recoil, i.e., they are recoilless. This is known as the Mossbauer effect.
Nuclear grade – It is a material of a quality adequate for use in nuclear application.
Nuclear island – It is that part of a nuclear power plant which incorporates all equipment, systems, installation and control and other relevant hardware installed within the reactor and reactor auxiliary buildings. The boundaries of the nuclear island are normally defined as being one metre outside the external boundaries of the above-mentioned buildings in the case of piping and two metres for cable.
Nuclear liability – It is the strict legal liability of the operator of the nuclear facility. Majority of the national nuclear liability laws worldwide are (i) the exclusive liability of the operator of the nuclear installation where the nuclear incident occurred, (ii) the strict (absolute) liability of such operator, (iii) the establishment of a maximum liability amount to be borne by the operator with the nuclear liability conventions providing for a minimum threshold (only a few countries have provided for unlimited liability under their nuclear liability legislation), (iv) the obligation for the operator to have and maintain financial security to cover its nuclear liability and ensure availability of funds, and (v) the obligation of the victims to file claims within a certain period (prescription period).
Nuclear life-cycle – It is a whole life-cycle approach to a nuclear power project consisting of several phases namely research and development, conceptual design, detailed design, construction, commissioning, operations and maintenance, refurbishment or life extension (if applicable), and decommissioning.
Nuclear magnetic resonance (NMR) – It is a physical phenomenon in which nuclei in a strong constant magnetic field are disturbed by a weak oscillating magnetic field (in the near field) and respond by producing an electro-magnetic signal with a frequency characteristic of the magnetic field at the nucleus. This process occurs near resonance, when the oscillation frequency matches the intrinsic frequency of the nuclei, which depends on the strength of the static magnetic field, the chemical environment, and the magnetic properties of the isotope involved. In practical applications with static magnetic fields up to around 20-tesla, the frequency is similar to VHF (very high frequency) and UHF (ultra-high frequency) television broadcasts (60 mega-hertz to 1,000 mega-hertz).
Nuclear magnetic resonance (NMR) spectroscopy – It is a technique which exploits the magnetic properties of certain atomic nuclei. This technique is useful for identifying unknown compounds. Nuclear magnetic resonance is a radio frequency (RF) spectroscopy involving the interaction of the nuclear magnetic dipole or electric quadrupole moments with external or internal magnetic fields or electric-field gradients. These interactions provide detailed information on the atomic (chemical) environment. Majority of the nuclear magnetic resonance spectra are got using radio transmitters, pulse generators, sensitive radio receivers, and a large laboratory electro-magnet. The frequency or the magnetic field is swept to get a resonance. The information in such a resonant spectrum includes line position, frequently related to the chemical shift or the metallic (Knight) shift, quadrupole splitting, and linewidths. This information can then be interpreted to give insight into the local atomic environment of those atoms responsible for the resonance.
Nuclear materials – It refers to the metals uranium, plutonium, and thorium, in any form, as per the International Atomic Energy Agency (IAEA). This is differentiated further into ‘source material’, consisting of natural and depleted uranium, and ‘special fissionable material’, consisting of enriched uranium (U-235), uranium-233, and plutonium-239. Uranium ore concentrates are considered to be a ‘source material’, although these are not subject to safeguards under the Nuclear Non-Proliferation Treaty.
Nuclear metallurgy – It is the branch of the metallurgy which deals with the science and technology of the nuclear materials.
Nuclear non-proliferation – It is a process by which the spread of nuclear weapons technology is prevented.
Nuclear particle – It is a sub-atomic particle found in the nucleus of an atom, such as a proton or a neutron. These particles are also called nucleons and are responsible for an atom’s mass. Some examples of nuclear particles include protons (positively charged), neutrons (neutral charge), and alpha particles (two protons and two neutrons).
Nuclear power – It is the use of nuclear reactions to produce electricity. Nuclear power can be obtained from nuclear fission, nuclear decay and nuclear fusion reactions. Presently, the vast majority of electricity from nuclear power is produced by nuclear fission of uranium and plutonium in nuclear power plants. Nuclear decay processes are used in niche applications such as radioisotope thermoelectric generators in some space probes. Reactors producing controlled fusion power have been operated since 1958 but have yet to generate net power and are not expected to be commercially available in the near future.
Nuclear power generation – It is the process of producing electricity by harnessing the heat from nuclear fission reactions, which uses the splitting of atoms like uranium-235 to create energy. This heat is used to create steam, which spins turbines connected to generators which produce electricity.
Nuclear power plant (NPP) – It is also known as a nuclear power station (NPS), nuclear generating station (NGS) or atomic power station (APS). It is a thermal power station in which the heat source is a nuclear reactor. As is typical of thermal power stations, heat is used to generate steam which drives a steam turbine connected to a generator that produces electricity. A nuclear power plant is divided into two main parts namely the nuclear island and the conventional island. The nuclear island is further sub-divided into the nuclear steam supply system and the balance of nuclear island i.e., everything else which needs to be designed, constructed and tested to complete the nuclear island.
Nuclear pressure equipment (NPE) – A nuclear pressure equipment is the reactor pressure vessel (RPV) in a nuclear power plant which is the pressure vessel containing the nuclear reactor coolant, core shroud, and the reactor core.
Nuclear quadrupole resonance (NQR) – It is a chemical analysis technique related to nuclear magnetic resonance (NMR). Unlike nuclear magnetic resonance, nuclear quadrupole resonance transitions of nuclei can be detected in the absence of a magnetic field, and for this reason nuclear quadrupole resonance spectroscopy is referred to as ‘zero field nuclear magnetic resonance’. The nuclear quadrupole resonance is mediated by the interaction of the electric field gradient (EFG) with the quadrupole moment of the nuclear charge distribution. Unlike nuclear magnetic resonance, nuclear quadrupole resonance is applicable only to solids and not liquids, since in liquids the electric field gradient at the nucleus averages to zero (the electric field gradient tensor has trace zero).
Nuclear radiation – It is the release of energy in the form of high-speed charged particles or electro-magnetic waves from an unstable atomic nucleus. This occurs during a process called radio-active decay, where the nucleus ejects energy to become more stable. The main types of nuclear radiation are alpha particles, beta particles, and gamma rays.
Nuclear reaction – It is a process in which two nuclei, or a nucleus and an external sub-atomic particle, collide to produce one or more new nuclides. Hence, a nuclear reaction causes a transformation of at least one nuclide to another.
Nuclear reactor – It is a device in which nuclear fission can be sustained and controlled in a self-supporting nuclear reaction. The varieties are several, but all incorporate certain features, including fissionable material or fuel, a moderating material (unless the reactor is operated on fast neutrons), a reflector to conserve escaping neutrons, provisions of removal of heat, measuring and controlling instruments, and protective devices. It is also a device in which a fusion chain reaction can be initiated, maintained, and controlled. Its essential components are fuel, shielding, and coolant. There are different approaches to fusion. Nuclear reactors are used at nuclear power plants for electricity generation. Nuclear reactor is the heart of a nuclear power plant.
Nuclear safeguards – These are technical, legal, and institutional measures which are used to verify that a country is using its nuclear material and facilities solely for peaceful purposes, and not for weapons development. These are applied to detect the diversion of nuclear material from the civilian fuel cycle and to provide assurance which countries are adhering to their international non-proliferation commitments. This is mainly done through independent verification by an organization like the International Atomic Energy Agency (IAEA).
Nuclear safety – It consists of the protection of people and the environment from the harmful effects of ionizing radiation.
Nuclear safety culture – IAEA safety series No. 75-INSAG-4 defines nuclear safety culture as ‘that assembly of characteristics and attitudes in organizations and individuals which establishes that, as an overriding priority, nuclear plant safety issues receive the attention warranted by their significance’.
Nuclear sensor – It is also known as a nuclear radiation detector. It is a device which detects and measures ionizing radiation like alpha, beta, and gamma rays. These sensors work by converting the effects of radiation on a detector material into a measurable signal, such as an electrical signal or light pulse. They are used in several applications, including monitoring safety in nuclear power plants, and environmental monitoring.
Nuclear steam supply system (NSSS) – It is that part of a nuclear power plant which incorporates the nuclear heat source, the heat transport system, and other systems directly connected to the nuclear steam supply system. It is normally referred to as ‘N-triple S’.
Nuclear structure – It is the atomic nucleus at the centre of the atom, containing more than 99.975 % of the total mass of the atom. Its average density is around 3 × 1,011 kilogram per cubic centimeter. Its diameter is around 10 to the power -12 centimeter and hence is much smaller than the diameter of the atom, which is around 10 to the power -8 centimeter. The nucleus is composed of protons and neutrons. The number of protons is denoted by ‘Z’, the number of neutrons by ‘N’. The total number of protons and neutrons in a nucleus is termed the mass number and is denoted by ‘A’ which is equal to ‘N + Z’.
Nuclear supply chain – It is the system of organizations, people, technology, activities, information and resources involved in moving nuclear energy from generator / supplier to customer.
Nuclear transmutation – It is the conversion of one chemical element or an isotope into another chemical element. Nuclear transmutation occurs in any process where the number of protons or neutrons in the nucleus of an atom is changed. A transmutation can be achieved either by nuclear reactions (in which an outside particle reacts with a nucleus) or by radioactive decay, where no outside cause is needed.
Nuclear waste – It is a particular type of radio-active waste which is produced as part of the nuclear fuel cycle. Radio-active waste is a broader term which includes all waste that contains radio-activity. Nuclear waste is produced as a result of the activities needed to produce nuclear fission. These include extraction of uranium from ore, concentration of uranium, processing into nuclear fuel, and disposal of by-products.
Nuclear waste management – It is the process of handling, treating, storing, and disposing of radio-active waste from nuclear facilities to protect human health and the environment. Management includes pre-treatment, treatment (like compacting or solidifying), packaging in special containers, interim storage, and final disposal in designated facilities, with the international consensus favouring deep geological repositories for high-level waste.
Nucleate boiling – It is a boiling regime characterized by the formation of vapour bubbles at nucleation sites on a heated surface, which then grow and detach from the surface. This process is highly efficient in transferring heat away from the surface and is frequently observed at low to moderate heat fluxes.
Nucleated grains – These refer to the initial formation of small, stable clusters (nuclei) within a material which then serve as the starting points for further crystal growth. This process, known as nucleation, is crucial in the formation of polycrystalline materials like metals and ceramics, and it governs the kinetics of phase transformations and recrystallization.
Nucleation – It is the initiation of a phase transformation at discrete sites, with the new phase growing on the nuclei. In case of the formation of non-metallic inclusion, nucleation is the stage in which nuclei of new phase are formed as a result of super saturation of the solution (liquid or solid steel) with the solutes (e.g., Al and O) due to dissolution of the additives (deoxidation or desulphurization agents) or cooling down of the steel. The nucleation process is determined by surface tension on the boundary inclusion-liquid steel. The less the surface tension, the lower super saturation is needed for formation of the new phase nuclei. The nucleation process is much easier in the presence of other phase (other inclusions) in the liquid steel. In this case the new phase formation is determined by the wetting angle between a nucleus and the substrate inclusion. Wetting condition (low wetting angle) are favorable for the new phase nucleation.
Nucleation kinetics – It is the rate of formation of stable nuclei.
Nucleation mechanism – It refers to the process by which a new phase forms, overcoming a barrier, and is classified into primary nucleation, occurring in crystal-free solutions, and secondary nucleation, which involves the generation of new crystals in the vicinity of existing crystals.
Nucleation processes – These processes play a key role in the solidification of castings by controlling to a large extent the initial structure type, size scale, and spatial distribution of the product phases. During several solidification processes, the size scale of critical nucleation events is too small and the rate of their occurrence too rapid for accurate observation by direct methods. Nonetheless, nucleation effects in the solidification micro-structure exert a strong influence on the grain size and morphology as well as the compositional homogeneity. The final micro-structure is also modified by the crystal growth, fluid flow, and structural coarsening processes which are important in the later stages of ingot freezing.
Nucleation rate – It is the number of new nuclei formed per unit time per unit volume during a phase transformation. It depends on the frequency of atoms attaching to form a nucleus and the number of stable nuclei, and it normally has a maximum value at a temperature below the equilibrium transition temperature. At higher temperatures, atomic mobility is high but the energy barrier is also high, while at lower temperatures, the energy barrier decreases but mobility slows down.
Nucleation site – It is a location on a surface or within a substance where a new phase (solid, liquid, or gas) can begin to form during a phase transition, such as boiling, freezing, or condensation. These sites are frequently imperfections or irregularities on a surface, or areas with specific chemical or physical properties which u the initiation of the new phase.
Nucleation stress – It is the critical stress needed to initiate a process, such as the formation of a dislocation in a crystal, the creation of a shear band, or the nucleation of a crack. This stress is influenced by factors like temperature, strain rate, and material properties. It is a key concept, determining when a material begins to deform plastically or fracture.
Nucleon – It is either a proton or a neutron, which is considered in its role as a component of an atomic nucleus.
Nucleophile – It is an atom or molecule which can donate an electron pair to another atom or molecule. All molecules or ions with a free pair of electrons or at least one pi bond can act as nucleophiles, by which they are attracted to electron-deficient regions of other species; a chemical reaction involving a nucleophile donating an electron pair to an electrophile can be referred to as nucleophilic attack. Because they donate electrons, nucleophiles are Lewis bases by definition.
Nucleus – It is the heavy central core of an atom, in which majority of the mass and the total positive electric charge are concentrated. It is the first structurally stable particle capable of initiating recrystallization of a phase or the growth of a new phase and possessing an interface with the parent metallic matrix. The term is also applied to a foreign particle which initiates such action.
Nuclide – It is a species of atom distinguished by the constitution of its nucleus. Nuclear constitution is characterized by its mass number, atomic number, and nuclear energy state, provided that the mean life in that state is long enough to be observable.
Nugget – It is a small mass of metal, such as gold or silver, found free in nature. It is the weld metal joining the work-pieces in a spot, seam, or projection welds.
Nugget size (resistance welding) – It is the diameter of a spot or projection weld or width of a seam weld measured in the plane of the faying surfaces.
Nugget zone – It is the central and most highly deformed area of a weld joint, particularly in solid-state welding processes like friction stir welding (FSW) and resistance spot welding (RSW). It is formed by the intense heat and mechanical force applied during the joining process, and it has a unique microstructure which is distinct from the surrounding material.
Null – It is a terminology denoting a state of no movement or a zero position within a conveyor system. Regular monitoring is essential to promptly identify unexpected null conditions.
Null field – It is a database field which that has no value, indicating that the data is missing, unknown, or not applicable, and is distinct from a field which contains a zero or a blank space. In other contexts, a ‘null field’ can refer to a point in a physical field where opposing forces cancel each other out, resulting in a net value of zero.
Null hypothesis – The null hypothesis represents a theory which has been put forward, normally as a basis for argument. The null hypothesis is normally simpler than the alternative hypothesis and is given special consideration. Hence, the conclusion is given in terms of the null hypothesis. Null hypothesis is the opposite of the study hypothesis. In general, this term relates to a particular study hypothesis being tested, as distinct from the alternative hypothesis, which is accepted if the study is rejected. Contrary to intuition, the null hypothesis is frequently a study hypothesis which the analyst prefers to reject in favour of the alternative hypothesis, but this is not always the case. Erroneous rejection of the null hypothesis is known as a Type I error, whereas erroneous acceptance of the null hypothesis is known as a Type II error.
Null zone – It is a designated area within a conveyor system where the absence of products or materials is intended. Regular monitoring is crucial to preserve the integrity of the null zone and address any inadvertent material accumulation.
Number 1 busheling scrap – This scrap is similar to punchings and plate scrap. For the most part, this scrap category contains more steel clippings (up to 300 millimeters in length). The scrap is clean steel scrap and includes new factory busheling (e.g., steel clipping, stamping, etc.). It does not include old auto body and fender stock. It is free of metal which is coated, limed, vitreous enameled, and electrical sheet containing over 0.5 % silicon.
Number 1 heavy melting scrap – This scrap category is characterized by a higher percentage of impurities than is found in cut plate and structural scrap, as well as higher alloy content since it normally consists of high-strength low-alloy (HSLA) steels. It is normally available in lengths under 1.5 meters for charging into basic oxygen furnaces and large electric arc furnaces. It can also include wrought iron and / or steel scrap of 6 millimeters and above in thickness. Individual pieces are normally not above 0.6 meters x 1.5 meters (charging-box size) prepared in a manner to ensure compact charging.
Number 1 scrap bundles – These bundles are also known as hydraulic bundles and are tightly compacted bales of light gauge scrap produced in hydraulic baling machines. The material is collected from press shops, and consists of clean sheets, strips, and trimmings which can also be categorized as punchings and plate scrap or as number 1 busheling scrap. These bundles can also include new black steel sheet scrap, clippings, or skeleton scrap, compressed to charging box size, and have a density of not less than 1.2 tons per cubic meter. The bundles are tightly secured for handling with a magnet. The bundles can include tightly secured mandrel wound bundles or skeleton reels, chemically de-tinned material, and old auto body and fender stock. The scrap bundles are free of metal which is coated, limed, vitreous enameled, and electrical sheet containing over 0.5 % silicon.
Number 2 heavy melting scrap – This scrap category differs from number 1 heavy melting scrap mainly in that the lower limit of thickness is 3 millimeters, and more coated steel is allowed. It includes wrought iron and steel scrap, black and galvanized steel, 3 millimeters and above in thickness. The scrap is of charging-box size and includes material not suitable as number 1 heavy melting scrap.
Number 2 scrap bundles – These bundles are also produced in hydraulic baling machines and contain considerable quantity of steel sheets which have been galvanized or otherwise coated with zinc. With these bundles, not only have the contaminants which result in a poor-quality melt, but also the yield is poor (around 70 %). These bundles consist of old black and galvanized steel sheet scrap, hydraulically compressed to charging box size and have density not less than 1.2 tons per cubic meter. The bundles do not include tin coated or lead coated material or vitreous enameled material.
Number 3 scrap bundles – These bundles are also produced in hydraulic baling machines and contain old steel sheet, compressed to charging box size. The bundles have density not less than 1.2 tons per cubic meter. It can include all coated ferrous scrap not suitable for inclusion in number 2 bundles.
Number density – It is a measure of the concentration of countable objects (atoms, and molecules etc.) in space, expressed as the number per unit volume.
Number of cycles to crack initiation – It refers to the number of load cycles a material can withstand before a crack of a specific, detectable size forms. This is a crucial parameter in understanding a material’s fatigue behaviour and predicting its lifespan.
Numerical analysis – It is the study of algorithms which use numerical approximation (as opposed to the symbolic manipulations) for the problems of mathematical analysis (as distinguished from discrete mathematics). It is the study of numerical methods which attempt to find approximate solutions of problems rather than the exact ones. Numerical analysis finds application in all fields of engineering. Current growth in computing power has enabled the use of more complex numerical analysis, providing detailed and realistic mathematical models in science and engineering.
Numerical aperture (NA) – It is the product of the lowest index of refraction in the object space multiplied by the sine of half the angular aperture of the objective.
Numerical code – It is the numerical designation of each class or sub-class of resource quantity as defined by the United Nations Framework Classification for Mineral Resources (UNFC). Numerical codes are always quoted in the same sequence (i.e., E, F, G).
Numerical control (NC) – It is also called computer numerical control (CNC). It is the automated control of tools by means of a computer. It is used to operate tools such as lathes, drills, mills, grinders, routers, and 3D-printers. Computer numerical control transforms a piece of material (metal, plastic, wood, ceramic, stone, or composite) into a specified shape by following coded programmed instructions and without a manual operator directly controlling the machining operation.
Numerical control programming – It is the process of developing a set of instructions which controls a machine tool or other manufacturing device to produce a part.
Numerical data – It is also known as quantitative data. It is information expressed in numbers which can be measured and counted. This type of data can be used in mathematical operations like addition and subtraction, and is used to represent quantities, making it useful for statistical analysis and visualization.
Numerical error – It is the difference between a computed, approximate value and the true, exact value. This error arises during numerical computations because of several factors like rounding off numbers, using approximations in calculations, or inherent limitations in the numerical methods themselves. Numerical error is either of two kinds of error in a calculation. The first (a rounding error) is caused by the finite precision of computations involving floating-point values. Increasing the number of digits allowed in a representation reduces the magnitude of possible roundoff errors, but any representation limited to finitely several digits still cause some degree of roundoff error for uncountably several real numbers. The second type of error (sometimes called the truncation error) is the difference between the exact mathematical solution and the approximate solution.
Numerical methods – These are mathematical techniques used to find approximate solutions to problems which are difficult or impossible to solve analytically. They use a step-by-step, iterative process, typically performed by computers, to get closer and closer to the correct answer. These methods are used to solve problems involving integrals, derivatives, differential equations, and large systems of equations in several fields including engineering.
Numerical modeling – It is a mathematical technique which uses computers to simulate the behaviour of a physical system, frequently involving complex equations which are difficult to solve analytically. It involves representing a physical process with mathematical equations and then using numerical methods to approximate solutions, making it possible to analyze and predict system behaviour under different conditions.
Numerical process modeling – It is a method of representing real-world processes using mathematical equations and numerical techniques. It involves creating a mathematical model which describes the behaviour of a system and then using numerical methods to solve the equations and simulate the process. This allows for analysis, prediction, and optimization of the process under different conditions.
Numerical techniques – These techniques refer to different methods used for solving mathematical problems through numerical approximation, including interpolation of measured data, spline fitting, data smoothing, and techniques for numerical integration and differentiation.
Numerical variable – It refers to a variable whose possible values are numbers (as opposed to categories).
Nusselt number – In thermal fluid dynamics, the Nusselt number is the ratio of total heat transfer to conductive heat transfer at a boundary in a fluid. Total heat transfer combines conduction and convection. Convection includes both advection and diffusion.
Nut – It is a type of fastener with a threaded hole. Nuts are almost always used in conjunction with a mating bolt to fasten multiple parts together. The two partners are kept together by a combination of their threads’ friction (with slight elastic deformation), a slight stretching of the bolt, and compression of the parts to be held together.
Nut coke – It is fraction of the coke in the size range of +10 millimeters to -30 millimeters. It is charged with the ore burden in the blast furnace.
Nutrients – Both nitrogen and phosphorus, along with carbon, are essential nutrients for growth. When discharged to the aquatic environment, these nutrients can lead to the growth of undesirable aquatic life. When discharged in excessive amounts on land, they can also lead to the pollution of groundwater.
Nutrient requirements (C:N:P ratio) – Maintaining the correct ratio between carbon, nitrogen, and phosphorus. (C:N:P ratio) is very important for plant nutrition but also for maintaining the correct chemical and biological balance of aquatic ecosystems. Besides carbon, hydrogen, and oxygen, bio-mass needs nitrogen, phosphorous, and micro-nutrients such as iron, calcium, magnesium, copper, zinc and so on. Most industrial wastewaters lack nitrogen and phosphorus which is to be added (in the form of urea, super-phosphate or ammonium phosphate) to maintain optimal microbial growth conditions. The minimum C:N:P ratio needed for optimal microbial growth in the in aerobic processes is 100:5:1, and anaerobic processes is 330:5:1.
n-value – It is also called the strain-hardening exponent. It is equal to the slope of the true stress / true strain curve up to maximum load, when plotted on log-log coordinates. The n-value relates to the ability of as sheet metal to be stretched in metal-working operations. The higher is the n-value, the better is the formability (stretchability).
Nylon – It is the generic name for all synthetic polyamides. It is polyamide which has high strength, high elongation, and good resistance to abrasion, fatigue and impact. While moisture absorption not as high as cotton, it absorbs up to 10 % of its own weight in moisture, and hence, it has poor dimensional stability.
Nylon-covered bearings – These are bearings within a conveyor system shielded with a layer of nylon material to augment durability and reduce friction. Regular checks are requisite to monitor wear, ensure proper alignment, and evaluate the overall condition of the bearings.
Nylon conveyor belt – It is a specific type of conveyor belt crafted from nylon material, renowned for its robustness and durability. Periodic inspections are necessary to evaluate wear patterns and maintain the overall condition of the nylon conveyor belt.
Nylon fabric – It is a fabric material which is derived from nylon fibres and utilized in different conveyor components, such as belts and covers. Regular checks are indispensable to uphold the integrity and durability of components fashioned from nylon fabric.
Nylon plastics – These are the plastics based on a resin composed principally of a long-chain synthetic polymeric amide which has recurring amide groups as an integral part of the main polymer chain. Numerical designations (nylon 6, nylon 6/6, and so on) refer to the monomeric amides of which they are made. These plastics are characterized by high toughness and elasticity.
Nylon-reinforced belt – It is a conveyor belt fortified with additional layers of nylon material for heightened strength and extended longevity. Regular inspections are essential to evaluate the condition, alignment, and wear of the nylon-reinforced belt.
Nylon ring elastic stop nut – It is also known as a nylon-insert lock nut or nyloc nut, It is a type of fastener which uses a nylon collar or ring inserted into the nut to create a locking mechanism This nylon insert deforms elastically when the nut is tightened, creating friction against the bolt threads and preventing the nut from loosening because of the vibration or other forces.
Nylon rollers – These are rollers within a conveyor system constructed from nylon material, recognized for their durability and resistance to wear. Regular inspections are necessary for ensuring proper alignment, assess wear, and confirm overall functionality.
Nylon-rubber compound – It is a specialized material compound integrated into conveyor components, amalgamating the advantageous properties of nylon and rubber to improve durability and flexibility. Regular checks are necessary to validate the integrity of components fashioned from the nylon-rubber compound.
Nylon slider bed – It is a conveyor bed design featuring a slider surface composed of nylon material. Frequent inspections are requisite to monitor wear patterns, assess alignment, and facilitate proper material flow on the nylon slider bed.
Nylon sprockets – These are sprockets incorporated into a conveyor system, constructed from nylon material and frequently used in chain-driven applications. Regular assessments are necessary to evaluate wear, ensure proper alignment, and confirm the overall condition of the sprockets.
Nylon wear strip – It is a strip composed of nylon material, strategically used to diminish friction and wear in specific areas of a conveyor system. Regular checks are essential to preserve the effectiveness of nylon wear strips.
Nylon webbing – it is the webbing material produced from nylon fibers, utilized in the construction of conveyor belts. Periodic inspections are crucial to assess the condition, alignment, and wear of the nylon webbing.
Nyquist criterion – It is a graphical method used in control systems engineering to determine the stability of a closed-loop system by analyzing the Nyquist plot of its open-loop transfer function. It assesses stability by examining how the Nyquist curve, which represents the frequency response of the open-loop system, encircles the critical point -1 + j0 on a complex plane. If the curve does not encircle this point, the system is generally stable.
Nyquist curve – It is a graphical method in control systems to assess the stability of a feedback system by plotting its open-loop transfer function in the complex plane as frequency varies. It uses polar coordinates, with the gain as the radial distance and phase as the angle, to show the system’s frequency response and determine stability by analyzing encirclements of the critical point (-1, 0) ae per the Nyquist criterion.
Nyquist diagram -It is a polar plot of a system’s open-loop frequency response, created by plotting the real and imaginary parts of the complex transfer function for all frequencies from –infinity to +infinity. It is a graphical tool used in control systems engineering to determine the absolute and relative stability of a closed-loop system by analyzing how the plot encircles the critical point (-1,0). The diagram provides information about a system’s gain and phase margins, which are key indicators of its stability.
Nyquist frequency – It is half the sampling rate of a discrete signal, representing the highest frequency which can be accurately captured and reconstructed. It is a key concept in the Nyquist-Shannon sampling theorem, which states that to avoid distortion called aliasing, the sampling rate is to be at least twice the highest frequency component of the original continuous signal. For example, if a signal is sampled at 44,100 hertz (like on an audio CD), the Nyquist frequency is 22,050 hertz.
Nyquist plot – It is a graphical method used to assess the stability of a feedback control system. It plots the complex frequency response of a system’s open-loop transfer function on a complex plane, with frequency varying from -infinity to +infinity. The real part of the transfer function is on the x-axis and the imaginary part is on the y-axis. Stability is determined by observing if the plot encircles the point (-1, j0), as per the Nyquist stability criterion.
Nyquist pulse – It is a type of signal pulse shaped to meet the Nyquist criterion by having a rectangular spectral profile, which minimizes inter-symbol interference (ISI) by ensuring the pulses have zero overlap in time at the sampling instants. This pulse shaping allows for higher data transmission rates while using minimal bandwidth, as it satisfies a specific condition for zero inter-symbol interference, making them valuable in high-speed digital communication systems.
Nyquist rate – It is the minimum sampling rate needed to accurately represent a continuous-time signal in the digital domain, ensuring no information loss during the conversion process. It is defined as twice the highest frequency component of the signal. Sampling at or above the Nyquist rate allows for perfect reconstruction of the original signal from its samples.
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