Glossary of technical terms for the use of metallurgical engineers Terms starting with alphabet ‘O’
Glossary of technical terms for the use of metallurgical engineers
Terms starting with alphabet ‘O’
Objective – It is an optical element that gathers light from an object being observed and focuses the light rays from it to produce a real image of the object. Objectives can be a single lens or mirror, or combinations of several optical elements. They are used in microscopes, binoculars, telescopes, cameras, slide projectors, compact disk players and countless other optical instruments. Objectives are also called object lenses, object glasses, or objective glasses.
Objective aperture – In optical microscopy, it is the working diameter of a lens or a mirror. It is used for accepting a transmitted wave or one of diffracted waves to get a bright-field image or a dark-field image. The objective aperture is inserted into the back focal plane of the objective lens.
Objective function – · In design optimization, it is the grouping of design parameters which is attempted to be maximized or minimized, subject to the problem constraints. It is also known as criterion function.
Objective lens – Objective lens of a microscope is the one at the bottom near the sample. At its simplest, it is a very high-powered magnifying glass, with very short focal length. This is brought very close to the specimen being examined so that the light from the sample comes to a focus inside the microscope tube. The objective itself is normally a cylinder containing one or more lenses which are typically made of glass. Its function is to collect light from the sample.
Objective turret – Majority of microscopes have several objective lenses mounted on a rotating turret to facilitate changing lenses. The objectives are mounted in ascending order of magnification so the user can easily change to progressively higher power lenses.
Object-oriented analysis and design – Object-oriented analysis and design is a technical approach for analyzing and designing an application, system, or business by applying object-oriented programming, as well as using visual modeling throughout the software development process to guide stakeholder communication and product quality. Object-oriented analysis and design in modern software engineering is typically conducted in an iterative and incremental way. The outputs of object-oriented analysis and design activities are analysis models (for object-oriented analysis) and design models (for object-oriented design) respectively. The intention is for these to be continuously refined and evolved, driven by key factors like risks and business value.
Object-oriented data-base management system – It is a database management system which supports the modelling and creation of data as objects.
Object-oriented management – It is a model for management and for project management. The objective of object-oriented management is to provide a clear set of principles set into a framework which enables all participants while minimizing management overhead.
Object-oriented programming – It is a computer programming model that organizes software design around data, or objects, rather than functions and logic.
Oblique evaporation shadowing – It consists of the condensation of evaporated material onto a substrate that is inclined to the direct line of the vapour stream to produce shadows.
Oblique illumination – It is the illumination from light inclined at an oblique angle to the optical axis.
Oblong weaves – These weaves are a development of square weaves for increasing the open screen area. With oblong weaves the number of weft wires is reduced, hence enlarging the mesh opening in the warp direction. The typical weave ratio of this asymmetrical mesh is 3:1. Customized weave ratios for specific requirements are also possible.
Observability – In control theory, it is the measure of how well the internal state of a system corresponds to its measurable outputs.
Observational data – Observational data are non-experimental data, and there is no control of potential confounding variables in the study. Because of the weak inferential grounds of statistical results based on observational data, the support for conclusions based on observational data is to be strongly supported by logic, underlying material explanations, identification of potential omitted variables and their expected biases, and caveats identifying the limitations of the study.
Observational study – It is the study in which the study treatments (or levels of the explanatory variables) are not randomly assigned to cases.
Observed value – It is the particular value of a characteristic determined as a result of a test or measurement.
Obvert level – It is the highest interior level of the sewer pipe, and which can be considered the ‘ceiling’ level, being the highest level of that sewer pipe.
Occluded gas – It consists of any of several gases which enter rocks or a mine atmosphere from pores, as feeders and blowers, and also from blasting operations. These gases pollute the mine air mainly by the absorption of oxygen by the coal, and in addition by chemical combination of oxygen with carbonaceous matter, for example, from decaying timbers, rusting of iron rails, burning of lights, and breathing of humans and animals. These gases include oxygen, nitrogen, argon, carbon dioxide, and methane.
Occupational health – It is normally defined as the science of the anticipation, recognition, evaluation, and control of hazards arising in or from the workplace which can impair the health and well-being of the employees, taking into account the possible impact on the surrounding communities and the general environment. This field is necessarily vast, encompassing a large number of disciplines and numerous workplace and environmental hazards. A wide range of structures, skills, knowledge, and analytical capacities are needed to coordinate and implement all of the ‘building block’ which make up the occupational health system so that protection is extended to both the employees and the environment. The scope of occupational health has evolved gradually and continuously in response to social, political, technological, and economic changes. In recent years, globalization of the world’s economies and its repercussions have been perceived as the greatest force for change in the world of work, and consequently in the scope of occupational health, in both positive and negative ways.
Occupational safety and health administration (OSHA) – It is a regulatory agency of the United States of America whose mission is to ‘assure safe and healthy working conditions for working men and women by setting and enforcing standards and by providing training, outreach, education, and assistance’. The agency is also charged with enforcing a variety of whistle-blower statutes and regulations. Its work-place safety inspections have been shown to reduce injury rates and injury costs without adverse effects on employment, sales, credit ratings, or organizational survival.
Occupational health and safety management system – Occupational health and safety constitutes a system which deals with the prevention of injuries and illnesses related to work, as well as the protection and improvement of the health of the employees. It aims to improve the working conditions and the surrounding environment. Occupational health includes promoting and maintaining the highest degree of physical and mental health and social well-being of the employees of all professions in the organization. In this context, the basic principles of the process of assessing and managing occupational hazards is based on the expectation, recognition, evaluation, and control of the risks arising in or from the workplace and which are harmful to the health and well-being of the employees. Occupational health and safety management systems have been defined as ‘a combination of the planning and review, the management organizational arrangements, the consultative arrangements, and the specific programme elements which work together in an integrated way to improve occupational health and safety performance’. These systems differ from earlier methods. They make those in the workplace more responsible for occupational health and safety, but this responsibility is discharged through an integrated management system rather than the earlier method consisting of ad-hoc structures and prescriptions.
Octahedral shearing stress theory – This theory states that the failure of a member by yielding occurs when the octahedral shearing stress in the member reaches the octahedral shearing stress at yielding in the simple tension or compression test.
Octet rule – It is a chemical rule of thumb which reflects the theory that main-group elements tend to bond in such a way that each atom has eight electrons in its valence shell, giving it the same electronic configuration as a noble gas. The rule is especially applicable to carbon, nitrogen, oxygen, and the halogens, although more generally the rule is applicable for the s-block and p-block of the periodic table.
Ocular – It is also known as eyepiece. It is a lens or system of lenses for increasing magnification in a microscope by magnifying the image formed by the objective.
Ocvirk number – It is a dimensionless number used to evaluate the performance of journal bearings, and defined by the equation ‘Ocvirk number = (P/eta x U) x (c/r)square x (d/b)square’ where ‘P’ is the load per unit width, ‘eta’ is the dynamic viscosity, ‘U’ is the surface velocity, ‘c’ is the radial clearance, ‘r’ is the bearing radius, ‘b’ is the bearing length, and ‘d’ is the bearing diameter. This number can be used in its inverted form and is related to the Sommerfeld number.
Odds – It is the ratio of probabilities for two different events for one group.
Odds ratio – It is the ratio of the odds of an event for two different groups.
OEM – It stands for original equipment manufacturer. OEM is an organization which manufactures and sells products or parts of a product that their buyer, another organization, sells to its own customers while putting the products under its own branding.
OEM vendors – They are suppliers of components to original equipment manufacturers (OEM), i.e., those who manufacture and sell the completely assembled product. For example, a typical OEM vendor
might provide small electrical motors to the producer of home appliances.
Oersted (Oe) – It is the coherent derived unit of the auxiliary magnetic field ‘H’ in the centimeter–gram–second system of units (CGS). It is equivalent to 1 dyne per maxwell.
Off-axis laminate – It is a laminate whose principal axis is oriented at an angle (theta) other than 0-degree or 90-degree with respect to a reference direction, normally related to principal load or stress direction.
Off-gas – It is a gas which is produced as a by-product of an industrial process or which is given off by a manufactured object or material.
Off gauge – It is the deviation of thickness or diameter of a solid product, or wall thickness of a tubular product, from the standard or specified dimensional tolerances.
Off-hand grinding – It is the grinding where the operator manually forces the wheel against the work, or vice versa. It frequently implies casual manipulation of either grinder or work to achieve the desired result. Dimensions and tolerances frequently are not specified, or are only loosely specified. The operator relies mainly on visual inspection to determine how much grinding should be done.
Off-set – It is the distance along the strain coordinate between the initial portion of a stress-strain curve and a parallel line which intersects the stress-strain curve at a value of stress (normally 0.2 %) that is used as a measure of the yield strength. The term is used for materials which have no obvious yield point. In statistical analysis, offset is the log of the length of the time period over which an event count is taken, entered into a regression model with its coefficient constrained to equal 1. This converts the study end point into the rate of event occurrence.
Off-set link chains – These chains have all links alike. These include integral link chains, such as bar-link, flat-top, and welded steel chains, where internal rollers cannot be installed.
Off-set modulus – It is the ratio of the off-set yield stress to the extension at the off-set point (plastics).
Off-set printing – It is a common printing technique in which the inked image is transferred (or ‘off-set’) from a plate to a rubber blanket and then to the printing surface. Offset printing is a widely used printing technique. It involves transferring an image from a plate to a rubber blanket, and then onto the desired printing surface. It is a cost-effective and high-quality method used to produce large quantities of printed materials. Offset printing involves several essential components which work together to produce high print quality. These components include the plate, blanket, ink, and printing press. The plate is typically made of aluminum and carries the image to be printed. The blanket acts as an intermediary, transferring the inked image from the plate to the printing surface. High-quality inks are used to ensure vibrant and accurate colour reproduction. The printing press is the machine which brings all these components together to produce the final printed material.
Off-set valve – It is a valve construction having inlet and outlet line connections on different planes, but 180-degree opposite each other.
Off-set yield strength – It is the stress at which the strain exceeds by a specific quantity (the off-set) an extension of the initial, approximately linear, proportional portion of the stress-strain curve. It is expressed in force per unit area.
Off-shore construction – It is the installation of structures and facilities in a marine environment, normally for the production and transmission of electricity, oil, gas and other resources. It is also called maritime engineering.
Off-site release – It means the release of a pollutant or radioactivity which leaves the plant site boundary.
Off-stream use – It consists of water withdrawn from a surface water source for uses such as industrial water supply, and steam electric power generation etc.
Off the bars – It means a situation when a nuclear power station is not generating electricity.
Ogive – It is also known as a cumulative frequency polygon, can refer to one of two things namely (i) any hand-drawn graphic of a cumulative distribution function, and (ii) any empirical cumulative distribution function. The points plotted as part of an ogive are the upper-class limit and the corresponding cumulative absolute frequency or cumulative relative frequency. The ogive for the normal distribution (on one side of the mean) resembles (one side of) an Arabesque or ogival arch, which is likely the origin of its name. Along the horizontal axis, the limits of the class intervals for an ogive are marked. Based on the limit values, points above each are placed with heights equal to either the absolute or relative cumulative frequency. The shape of an ogive is obtained by connecting each of the points to its neighbours with line segments.
Ohm – It is the unit of electrical resistance in the International System of Units (SI). The ohm is defined as an electrical resistance between two points of a conductor when a constant potential difference of one volt (V), applied to these points, produces in the conductor a current of one ampere (A), the conductor not being the seat of any electromotive force.
Ohm-meter – It is an instrument for the measurement of electrical resistance.
Ohm’s law – It states that the electric current through a conductor between two points is directly proportional to the voltage across the two points. Introducing the constant of proportionality, the resistance, one arrives at the three mathematical equations used to describe this relationship. These three equations are (i) V = IR, (ii) I = V/R, and (iii) R = V/I, where ‘I’ is the current through the conductor, ‘V’ is the voltage measured across the conductor, and ‘R’ is the resistance of the conductor. More specifically, Ohm’s law states that the ‘R’ in this relation is constant, independent of the current. If the resistance is not constant, the previous equation cannot be called Ohm’s law, but it can still be used as a definition of static / direct current resistance. Ohm’s law is an empirical relation which accurately describes the conductivity of the vast majority of electrically conductive materials over several orders of magnitude of current. However, some materials do not obey Ohm’s law. These materials are called non-ohmic.
Oil – It is a liquid of vegetable, animal, mineral, or synthetic origin which feels slippery to the touch.
Oil-based paints – These are the paints with films which form solids by the air-induced cross-linking of certain unsaturated plant oils known as drying oils. Oxygen is consumed in the process.
Oil burner – It is a burner for firing oil. The purpose of the oil burner is to mix the fuel oil with enough air to cause heat release from the fuel. This act needs the combustion of the fuel, but the combustion takes place outside the burner, that is at the tip. The performance of the burner is achieved by proper air-fuel mixing. The good burner mixes well and liberates a maximum amount of heat from the fuel. A poor burner does not accomplish this task well at all. Oil burners for industrial use are normally classified according to the method used for atomizing the oil.
Oil canning – It is a dished distortion in a flat or nearly flat sheet metal surface.
Oil content – It is the quantity of oil which an impregnated part, such as a self-lubricating bearing, retains.
Oil cooling – It is the use of engine oil as a coolant, typically to remove surplus heat from an internal combustion engine. The hot engine transfers heat to the oil which then normally passes through a heat-exchanger, typically a type of radiator known as an oil cooler. The cooled oil flows back into the hot object to cool it continuously.
Oil country tubular goods (OCTG) – Oil country tubular goods is a collective term applied in the oil and gas industries to three kinds of pipes used in oil wells namely (i) drill pipe, (ii) casing, and (iii) tubing. These products conform to respective standard specifications. The chemical composition requirements and the strength requirements are given in the respective standards. Drill pipe is used to transmit power by rotary motion from ground level to a rotary drilling tool below the surface and to convey flushing media to the cutting face of the tool. Drill pipe is produced in sizes ranging from 60 millimeters to 170 millimeters in outside diameter. Size designations refer to actual outside diameter and weight per meter. Drill pipe is usually upset, either internally or externally, or both, and is prepared to accommodate welded-on types of joints. Casing is used as a structural retainer for the walls of oil or gas wells, to exclude undesirable fluids and to confine and conduct oil or gas from productive sub-surface strata to ground level. Casing is produced in sizes from 110 millimeters to 500 millimeters outside diameter. Size designations refer to actual outside diameter and weight per meter. Ends are normally threaded and furnished with couplings, but can be prepared to accommodate other types of joints. Tube is used within the casing of oil wells to conduct oil and gas to ground level. It is produced in sizes from 25 millimeters to 115 millimeters in outside diameter, in several weights per meter. Ends are threaded for special integral type joints or fitted with couplings and may or may not be upset externally.
Oil cup – It is a device connected to a bearing which uses a wick, valve, or other means to provide a regulated flow of lubricant.
Oil, crude – It means a mixture of hydro-carbons which exists in liquid phase in natural underground reservoirs and remains liquid at atmospheric pressure after passing through surface separating facilities.
Oil, diesel – It is a liquid fuel specifically designed for use in a diesel engine, a type of internal combustion engine in which fuel ignition takes place without a spark as a result of compression of the inlet air and then injection of fuel. Hence, diesel fuel needs good compression ignition characteristics. The most common type of diesel fuel is a specific fractional distillate of petroleum fuel oil.
Oil drilling – It is a complex process which involves the drilling and pumping of oil from underground wells.
Oil-filled, inert-gas system, transformer – A positive seal of the transformer oil can be provided by an inert-gas system. Here, the tank is slightly pressurized by an inert gas such as nitrogen. The main tank gas space above the oil is provided with a pressure gauge. Since the entire system is designed to exclude air, it is required to operate with a positive pressure in the gas space above the oil, otherwise, air is admitted in the event of a leak. Smaller station service units do not have nitrogen tanks attached to automatically add gas, and it is common practice to add nitrogen yearly early winter as the tank starts to draw partial vacuum, because of the cooler weather. The excess gas is expelled each summer as loads and temperatures increase. Some systems are designed to add nitrogen automatically from the pressurized tanks when the pressure drops below a set level. A positive pressure of around 3.5 kilopascal (kPa) to 35 kilopascal is maintained in the gas space above the oil for preventing the ingress of air. This system includes a nitrogen gas cylinder, three-stage pressure-reducing valve, high-pressure and low-pressure gauges, high-pressure and low-pressure alarm switch, an oil / condensate sump drain-valve, an automatic pressure-relief valve, and necessary piping.
Oil-filled – self-cooled transformers – In small-sized and medium-sized transformers, cooling takes place by direct radiation from the tank to surrounding air. In oil-filled, self-cooled types, tank surfaces can be corrugated to provide a larger radiating surface. Oil in contact with the core and windings rises as it absorbs heat and flows outward and downward along tank walls, where it is cooled by radiating heat to the surrounding air. These transformers can also have external radiators attached to the tank to provide larger surface area for cooling.
Oil film bearings – These are machine elements which designed to produce smooth (low friction) motion between solid surfaces in relative motion and to generate a load support for mechanical components. The lubricant between the surfaces is a liquid is a lubricating oil. Oil film bearings are hydrodynamic bearings. These bearings are flood lubricated, precision journal bearings which operate on a hydro-dynamically generated film of oil. These bearings completely enclose the roll neck. The bearing surfaces are separated by a liquid film. These bearings have a low co-efficient of friction at high speeds. They have a long life and low space requirement. These are used in flat rolling in slabbing mills, hot strip mills and cold rolling mills. Oil film bearing being of hydrodynamic design distributes the bearing load over a large area with no concentration points. The film of oil on which the bearing operates has enormous load carrying capacity. Because of its continuous, unbroken nature, the film eliminates wear caused by metal-to-metal contact. This oil film is constantly maintained by the hydrodynamic action of the rotating sleeve to which a surplus of oil is presented at controlled temperatures.
Oil flow rate – it is the rate at which a specified oil passes through a porous sintered compact under specific test conditions.
Oil fog lubrication – It is the lubrication by an oil mist produced by injecting oil into a gas stream.
Oil, fuel – It consists of any of the different fractions got from the distillation of crude oil. Such oils include distillates (the lighter fractions) and residues (the heavier fractions). Fuel oils include heavy fuel oil (bunker fuel), marine fuel oil (MFO), furnace oil (FO), gas oil (gasoil), heating oils, diesel fuel, and others. The term fuel oil normally includes any liquid fuel which is burned in a furnace or boiler to generate heat, or used in an engine to generate power. However, it does not normally include other liquid oils, such as those with a flash point of around 42 deg C, or oils burned in cotton-wick or wool-wick burners. In a stricter sense, fuel oil refers only to the heaviest commercial fuels which crude oil can yield, i.e., those fuels heavier than gasoline (petrol) and naphtha. Fuel oil consists of long-chain hydro-carbons, particularly alkanes, cyclo-alkanes, and aromatics. Small molecules, such as those in propane, naphtha, gasoline, and kerosene, have relatively low boiling points, and are removed at the start of the fractional distillation process. Heavier petroleum-derived oils like diesel fuel and lubricating oil are much less volatile and distill out more slowly.
Oil, furnace – It is a dark viscous residual fuel got by blending mainly heavier components from crude distillation. Furnace oil is classified into four grades namely low viscosity, medium viscosity 1, medium viscosity 2, and high viscosity. Furnace oil falls under the category of Class C, under PESO (Petroleum and Explosives Safety Organization) classification.
Oil groove – It consists of a channel or channels cut in a bearing to improve oil flow through the bearing. A similar groove can be used for grease-filled bearings.
Oil hardening – It is quench-hardening treatment involving cooling in oil.
Oil heating and pumping set – It is a group of apparatus consisting of a heater for raising the temperature of the oil to produce the desired viscosity, and a pump for delivering the oil at the desired pressure.
Oil impregnation – It consists of filling of a sintered skeleton body with oil by capillary attraction or under the influence of an external pressure or a vacuum.
Oiliness – It is the ability of a lubricant to reduce wear and friction, other than by its purely viscous properties.
Oil-less bearing – It is the non-standard term for self-lubricating bearing which is a sintered product whose accessible pore volume is filled with a liquid lubricant which produces a lubricating film on the bearing surface during running of a shaft. This is because of a pumping action of the shaft and the frictional heat which lowers the viscosity of the oil. After completion of the running cycle, the oil is reabsorbed into the pore system of the bearing by capillary action.
Oil-lift drop hammer – It is also known as hydraulic gravity power drop hammer. In this hammer, the ram is lifted with oil pressure against an air cushion. The compressed air slows down the upstroke of the ram and contributes to its acceleration during the down stroke.
Oil, light diesel – it is a blend of distillates feed and residual oil. It is primarily recommended for stationary or slow speed diesel engines and as Industrial Fuel. Light diesel oil is a Class C product, under Petroleum and Explosives Safety Organization classification.
Oil-permeability – It is a measure of the capacity of the sintered bearing to allow the flow of an oil through its open pore system.
Oil pocket – It consists of a depression which is designed to retain oil in a sliding surface.
Oil quenching – It means hardening of carbon steel in an oil bath. Oils are categorized as conventional, fast, martempering, or hot quenching. Oil quenching facilitates hardening of steel by controlling heat transfer during quenching, and it improves wetting of steel during quenching to minimize the formation of undesirable thermal and transformational gradients which can lead to increased distortion and cracking.
Oil resistant conveyor belt – Ordinary grade belts are damaged quickly by imbibition of oil into cover rubber, peeling of cover rubber, and reverse troughing of the belt if oily materials are transported. Hence, oil resistant belts are to be used to transport oily materials.
Oil ring lubrication – It consists of a system of lubrication for horizontal shafts. It is a ring of larger diameter which rotates with the shaft and collects oils from a container beneath.
Oils and greases – Oils and greases are complex mixtures of hydrocarbons and degradable under bacterial action. The bio-degradation rate is different for different oils and greases with the bio-degradation rate for the tars being one of the slowest. Oil enters in to water through oil spills, leak from oil pipes, and waste water from the by-product plant of the coal carbonization plant. Being lighter than water, oils and greases spread over the surface of water, separating the contact of water with air, hence resulting in reduction of the dissolved oxygen. A surface film of oil on water restricts reoxygenation and together with bacterial degradation of the oil hydrocarbons causes the dissolved oxygen content to fall quickly. Oils and greases are also responsible for endangering water birds and coastal plants due to coating of oily materials and adversely affecting their normal activities. It also results in reduction of light transmission through surface waters, thereby reducing the photosynthetic activity of the aquatic plants. Oils include polycyclic aromatic hydrocarbons (PAH), some of which are known to be carcinogenic.
Oil staining – It is the surface staining which is caused by the partial decomposition during thermal treatment of residual lubricant.
Oil starvation – It is a condition in which a bearing, or other tribo-component, which receives an inadequate supply of lubricant.
Oil well – It is a drillhole boring in earth which is designed to bring petroleum oil hydro–carbons to the surface. Normally some natural gas is released as associated petroleum gas along with the oil. A well which is designed to produce only gas can be termed a ‘gas well’. Wells are created by drilling down into an oil or gas reserve and if necessary equipped with extraction devices such as pump-jacks.
Oil whirl – It is the instability of a rotating shaft which is associated with instability in the lubricant film. Oil whirl is to be distinguished from shaft whirl, which depends only on the stiffness of the shaft.
Old or post-consumer scrap – It results when industrial and consumer steel products (such as automobiles, appliances, buildings, bridges, ships, cans, railroad coaches and wagons, etc.) have served their useful life. Old scrap is collected after a consumer cycle, either separately or mixed, and it is frequently contaminated to a certain degree, depending highly on its origin and the collection systems.
Olefin – It is also known as alkene. It is a hydro-carbon containing a carbon-carbon double bond. The double bond can be internal or in the terminal position. Terminal alkenes are also known as alpha-olefins.
Oleic acid – It is a fatty acid that occurs naturally in different animal and vegetable fats and oils. It is an odorless, colorless oil, although commercial samples can be yellowish because of the presence of impurities.
Oleum – It is a term referring to solutions of different compositions of sulphur trioxide in sulphuric acid, or sometimes more specifically to di-sulphuric acid (also known as pyro-sulphuric acid). It is a strong oxidant. It reacts with combustible and reducing materials and organic materials. This generates fire and explosion hazard. Oleums can be described by the formula ySO3·H2O where ‘y’ is the total molar mass of sulphur tri-oxide content. The value of ‘y’ can be varied, to include different oleums. They can also be described by the formula H2SO4.xSO3 where ‘x’ is now defined as the molar free sulphur tri-oxide content. Oleum is normally assessed according to the free SO3 content by mass. It can also be expressed as a percentage of sulphuric acid strength, for oleum concentrations, that would be over 100 %.
Olsen ductility test, Olsen cup test – It is a cupping test in which a piece of sheet metal, restrained except at the centre, is deformed by a standard steel ball until fracture occurs. The height of the cup at the time of fracture is a measure of the ductility.
Oligotrophic – It is also known as eutrophic, hypereutrophic, and mesotrophic. It pertains to a lake or other body of water characterized by extremely low nutrient concentrations such as nitrogen and phosphorous and resulting very moderate productivity.
Olivine – It is a naturally occurring mineral of the composition (Mg,Fe)2SiO4 which is crushed and used as a moulding sand.
Omega phase – It is a non-equilibrium, sub-microscopic phase which forms as a nucleation growth product. It is frequently thought to be a transition phase during the formation of alpha from beta. It occurs in metastable beta alloys and can lead to severe embrittlement. It typically occurs during aging at low temperature, but can also be induced by high hydrostatic pressures.
Omitted variable bias – Variables which affect the dependent variable that are omitted from a statistical model are problematic. Irrelevant omitted variables cause no bias in parameter estimates. Important variables which are uncorrelated with included variables also cause no bias in parameter estimates, but the estimate of ‘sigma’ square biased high. Omitted variables which are correlated with an included variable X1 produce biased parameter estimates. The sign of the bias depends on the product of the covariance of the omitted variable and X1 and b1, the biased parameter. For example, if the covariance is negative and b1 is negative, then the parameter is biased positive. In addition, ‘sigma’ square is also biased.
One-coat ware – It consists of work-pieces finished in a single coat of porcelain enamel. It is also known as one-coat work. It is also sometimes a contraction of one-cover-coat ware in which the finish consists of a single cover coat applied over the ground coat.
One-line diagram – It is popularly known as single-line diagram (SLD). It is a simplest symbolic representation of an electric power system. The one-line diagram typically corresponds to more than one physical conductor. In a direct current system, the line includes the supply and return paths, in a three-phase system, the line represents all three phases (the conductors are both supply and return because of the nature of the alternating current circuits). The one-line diagram has its largest application in power flow studies. Electrical elements such as circuit breakers, transformers, capacitors, bus bars, and conductors are shown by standardized schematic symbols. Instead of representing each of three phases with a separate line or terminal, only one conductor is represented.
One-tail test – It is a test of hypothesis for which the study hypothesis is directional, i.e., if the null hypothesis is false, the true parameter value is hypothesized to be either strictly above the null-hypothesized value or strictly below it. One-tail test is also known as a one-sided test, a test of a statistical hypothesis in which the region of rejection consists of either the right-hand tail or the left-hand tail of the sampling distribution of the test statistic. Philosophically, a one-sided test represents the analyst’s a priori belief that a certain population parameter is either negative or positive.
One-way analysis of variance (ANOVA) – It is an extension of the independent group t-test where one has more than two groups. It computes the difference in means both between and within groups and compares variability between groups and variables. Its parametric test statistic is the F-test.
On/off permanent magnets – These have the safety of an ‘always on’ permanent magnet and the controlled ‘on/off’ of an electro-magnet. These magnets frequently use rare earth magnetic
material in two separate fields. When both fields are lined up, ‘north to north’ and ‘south to south’, the magnetic field goes down into the steel. When one field is reversed, caused by rotating the ‘on/off’ handle, the field stays within the magnet, no longer holding the steel. The ‘on/off’ magnets normally have two parallel poles which give this magnet a deep penetrating magnetic field for rougher, and flat surfaces and work well on round pipe or shaft material. When this type of permanent magnet is ‘off’ all collected fuzz iron falls away. In most sizes, the ‘on/off’ magnet is needed to be on steel to rotate the handle to the ‘on’ position. This is a safety feature which prevents pre-energizing of the magnet prior to being placed on steel, reducing the chance of injury or equipment damage.
Opacifier – It is a material which imparts or increases the diffuse reflectance of porcelain enamel.
Opacity – In porcelain enamel, it is the property of reflecting light diffusely and non-selectively.
Open-back inclinable press – It consists of a vertical crank press which can be inclined so that the bed has an inclination normally varying from 0-degree to 30-degree. The formed parts slide off through an opening in the back. It is frequently called an OBI press.
Open-circuit potential – It is the potential of an electrode measured with respect to a reference electrode or another electrode when no current flows to or from it.
Open-cell foam – It is the foamed or cellular material with cells which are normally inter-connected. Closed cell refers to cells which are not inter-connected.
Open-circuit time constant method – It is a method for approximately evaluating the transfer function of an electrical network.
Open-circuit voltage – It is the voltage which is developed at the terminals of a device with no load connected.
Open crack – It is a crack or tear in the surface of a brick or block whose length is more than 10 millimeters and whose width is more than 0.2 millimeters.
Open cycle vapour recompression – The open cycle vapour recompression uses compression to increase the pressure (and consequently the temperature) of the waste vapour. Mechanical vapour recompression uses a mechanical compressor, while thermal vapour recompression uses a steam ejector, and hence is heat driven rather than mechanically driven.
Open-die forging – It consists of the hot mechanical forming of metals between flat or shaped dies in which metal flow is not completely restricted. It is also known as hand or smith forging. Open-die forging can be distinguished from most other types of deformation processes in that it provides discontinuous material flow as opposed to continuous flow. Forgings are made by this process when (i) the forging is too large to be produced in closed dies, (ii) the needed mechanical properties of the worked metal which can be developed by open-die forging cannot be obtained by other deformation processes, (iii) the quantity needed is very small to justify the cost of closed dies, and (iv) the delivery date is too close to permit the fabrication of dies for closed-die forging. All forgeable metals can be forged in open dies.
Open dies – These are dies with flat surfaces which are used for preforming stock or producing hand forgings.
Open drip proof (ODP) motors – These motors allow air to circulate through the windings for cooling, but prevent drops of liquid from falling into motor within a 15-degree angle from vertical. Typically these motors are used for indoor applications in relatively clean, and dry locations.
Open hearth furnace – It is a reverberatory melting furnace with a shallow hearth and a low roof. The flame passes over the charge on the hearth, causing the charge to be heated both by direct flame and by radiation from the roof and sidewalls of the furnace.
Open hole compression (OHC) test – This test is used to determine the influence of a hole on the compressive strength of a laminate. The ratio of the open hole compression strength to compressive strength of the same unnotched laminate provides the open hole compression strength knockdown factor.
Open industrial control panels – An open industrial control panel is comprised of a mounting sub-panel and all components mounted to the sub-panel. It is intended for installation into an enclosure in the field. This category also covers industrial control panel enclosures. The enclosures can contain ventilation openings, observation windows, conduit fittings, environmental control devices, or maintenance luminaires. These control panels include wiring, terminals, and several other types of components, as well as mounting devices attached to a sub-panel which do not include a complete enclosure. The enclosure which is included with this type of industrial control panel is only intended to be a part of the overall installation. An open industrial control panel includes internal wiring, field wiring terminals, and components mounted on a sub-panel without a complete enclosure.
Open moulding – It is also known as contact moulding, open laminating, and wet lay-up. It is the method used longest in the polymer-matrix composites industry to make thermoset composite products, and it is still the selected production process for a wide range of composite products. It is a basic process which provides several of the advantages of composites processing, using relatively basic materials technology and processing methods. The moulding method involves placing reinforcements and liquid resin onto the surface of an open mould (which may or may not be precoated with gel coat), or onto other substrates, as, for example, when making a one-off sandwich construction, when making on-site repairs by applying a reinforcing vacuum-formed acrylic, corrosion-resistant lining on steel, or when making on-site repairs of tanks and pipes. The hand lay-up version involves applying the reinforcements and the resin by hand, while the spray-up version uses tailored spray equipment to deposit both reinforcements and resin on the mould or an alternative substrate.
Open pit mine – It is a mine that is entirely on surface. It is also referred to as open-cut or open-cast mine.
Open pore – It is a pore which is open to the surface of a compact. Open pore is connected with a network of connecting pores.
Open pores – These are pores in a refractory which are penetrated by the immersion liquid in the test specified in ISO 5017. These pores are, in principle, all those which are connected with the atmosphere, either directly or through one another.
Open porosity – It consists of a network of connecting pores in a sintered object which permits a fluid or gas to pass through the object.
Open rod press – It is a hydraulic press in which the slide is guided by vertical, cylindrical rods (normally four) which also serve to hold the crown and bed in position.
Open-sand casting – It is the casting made in a mould which has no cope or other covering.
Open systems inter-connection (OSI) model – It is a conceptual model created by the International Organization for Standardization (ISO) which enables diverse communication systems to communicate using standard protocols. In plain English, the open systems inter-connection provides a standard for different computer systems to be able to communicate with each other. The open systems inter-connection model can be seen as a universal language for computer networking. It is based on the concept of splitting up a communication system into seven abstract layers, each one stacked upon the last. Each layer of the open systems inter-connection model handles a specific job and communicates with the layers above and below itself.
Open type roll stand housings – They have a removable top connected to the housing by screws for easier rolls changing. Open type housings facilitate easy removal of rolls. When the housings have to withstand large horizontal forces, the pillars are made with an I-section. The integrally cast construction presents many difficulties in manufacturing. In such case the housing can be made up of two forged pillars bolted to two cast cross beams.
Operating control – In a boiler, it is a control to start and stop the burner. It is in addition to the high limit control.
Operating hazard analysis (OHA) – It is a hazard analysis which focuses on operating the product, including testing, maintaining, repairing, transporting, and handling. In this analysis, emphasis is on people performing tasks.
Operating pressure – It is the pressure at which a boiler is operated.
Operating stress map – It is one way to assess potential fracture for an alloy of given toughness and operating stress. Operating stress maps are based on the same principle as a residual strength diagram. Construction of an operating stress map is based on calculations of net section yield and fracture mechanics.
Operating system – It is the system software which manages computer hardware and software resources, and provides common services for computer programmes. Time-sharing operating systems schedule tasks for efficient use of the system and can also include accounting software for cost allocation of processor time, mass storage, peripherals, and other resources. For hardware functions such as input and output and memory allocation, the operating system acts as an intermediary between programmes and the computer hardware, although the application code is normally executed directly by the hardware and frequently makes system calls to an operating systems function or is interrupted by it. Operating systems are found on several devices which contain a computer.
Operating temperature – Itis the allowable temperature range of the local ambient environment at which an electrical or mechanical device operates. The device operates effectively within a specified temperature range which varies based on the device function and application context, and ranges from the minimum operating temperature to the maximum operating temperature (or peak operating temperature). Outside this range of safe operating temperatures, the device can fail.
Operation – It refers to the everyday running of the plant. This involves several activities such as (i) proper starting and stopping of the plant, (ii) the correct handling of the plant to ensure long component life, (iii) ensure such setting of the plant so that the products produced are as per the specification needed by the customer, (iv) running of the plant efficiently for meeting of the targets and the capacities, (v) running of the plant without the violation of the technological discipline, and (vi) running of the plant with meeting of all the requirements for the safety of both the personnel and the plant. The proper operation results into (i) high plant productivity, (ii) motivated plant operators, (iii) optimum use of the plant, and (v) a reduction in breakdowns and maintenance needs.
Operational amplifier – It is a type of amplifier with differential inputs. It is widely used in circuits where feed-back determines the circuit properties.
Operational considerations – It is important in the selection of crusher and includes power demand, equipment availability (hours / annum), availability and cost of replaceable parts, reduction ratio, maintenance requirements, needed manpower, approachability of parts for maintenance, availability of spares, safety and environment.
Operational discipline – It means complying with a set of ‘well thought out’ and ‘well defined’ processes, and consistently executing them correctly. It is defined as ‘the deeply rooted dedication and commitment by every member of an organization to carry out each task the right way every time’. In short, operational discipline can be stated as ‘everyone in the organization doing it right every time’. It means complying with a set of well thought out and well-defined processes, and consistently executing them correctly. It is an essential ingredient when trying to achieve operational excellence. Operational discipline provides an organized and systematic way to complete tasks and implement operational changes through a fundamental set of procedures which are specific to the steel organization’s unique product. Regardless of the final products of the steel plant, operational discipline increases reliability and decreases the risk of the occurrence of a high magnitude incident.
Operation plan – It describes the specific steps in any given strategic planning model and explains how and what portion of resources are going to be put into operation during a given operational period. The operational plan is the basis for, and justification of, an annual operating budget needed to achieve an overall strategic plan. It draws from an organization’s strategic plans to describe organizational missions and goals, organizational objectives, and organizational activities. While an operational plan can differ depending on the industry sector, the core components of an operational plan includes bench-marking and determining how progress is measured.
Operational planning (OP) – It is the process of implementing strategic plans and objectives to reach specific goals. Operational planning is one of the four basic types of planning involved in organizational management.
Operational testing, magnets – New and reinstalled lifting magnets are to be tested by a qualified person, or a designated person under the direction of a qualified person, prior to initial use to verify compliance with applicable provisions, including, but not limited to (i) moving parts, (ii) latches, (iii) stops, (iv) switches, (v) control devices, and (vi) alarms. Altered, repaired, or modified lifting magnets are to be tested by, or under the direction of, a qualified person. The test can be limited to the provisions affected by the alteration, repair or modification as determined by a qualified person with guidance from the manufacturer. All indicator lights, gauges, horns, bells, alarms, pointers and other warning devices are to be tested. Reports with date of all operational tests are to be made available.
Operation and maintenance costs – It is the operational costs of running a plant excluding fuel and any capital costs.
Operation and maintenance manual – Operation and maintenance (O&M) manual for an equipment / facility (frequently referred as ‘plant’) is necessary for the smooth operation of the plant. The operation and maintenance manual serves as an important tool for existing and new employees to safely and successfully operate and maintain the plant. When put together properly, employees at the workplace are able to utilize the operation and maintenance manual as a quick reference guide for anything from trouble-shooting to facing of an emergency during the plant operation. It provides necessary details about the upkeep of the plant. The manual also summarizes the actions necessary and identify those steps needed for cost effective, efficient, safe, and reliable plant operation.
Operator console – It is an electronic device which is used to control various field equipment in a production unit. Operator consoles are designed for ergonomic mounting of all types of operator interface devices: pushbuttons, display screens, human machine interfaces (HMIs), gauges, and meters etc. Larger free-standing consoles include ample enclosure space for other control devices to be mounted on interior sub-panels.
Operator work-stations – These are used for monitoring all system operations and for effecting control actions and parameter adjustments. These operator workstations are normally referred to as ‘clients’ since they get their current and historical data from the ‘server’ computer. There are normally multiple operator workstations for a production unit, each of which contains all of the process graphic displays and historical trend displays for the system.
OPEX – It means operating expenses. An operating expense is an expenditure which an organization incurs as a result of performing its normal operations.
Opinion – It is a belief or conviction, based on what seems probable or true but not demonstrable fact. The collective views of a large number of people, especially on some particular topic. Several studies have shown that individuals do not possess the skills to adequately assess risk or estimate probabilities, or predict the natural process of randomness. Hence, opinions can frequently be contrary to statistical evidence.
Optical axis – It is the line formed by the coinciding principal axes of a series of optical elements comprising an optical system. It is the line passing through the centers of curvature of the optical surfaces.
Optical emission spectrometry – It involves applying electrical energy in the form of spark generated between an electrode and a metal sample, whereby the vapourized atoms are brought to a high energy state within a so-called ‘discharge plasma’. These excited atoms and ions in the discharge plasma create a unique emission spectrum specific to each element. Hence, a single element generates several characteristic emission spectral lines.
Optical emission spectroscopy – It is pertaining to emission spectroscopy in the near-ultraviolet, visible, or near-infrared wave-length regions of the electro-magnetic spectrum. Optical emission spectroscopy is a well trusted and widely used analytical technique used for determining the elemental composition of a broad range of metals. The type of samples which can be tested using optical emission spectroscopy include samples from the melt in primary and secondary metal production, and in the metals processing industries, tubes, bolts, rods, wires, plates and many more. The part of the electromagnetic spectrum which is used by optical emission spectroscopy includes the visible spectrum and part of the ultraviolet spectrum. In terms of wave-length, it ranges from 130 nanometers up to around 800 nanometers.
Optical etching – It consists of development of micro-structure under application of special illumination techniques, such as dark-field illumination, phase contrast illumination, differential interference contrast illumination, and polarized light illumination.
Optical fibre – It is a flexible glass or plastic fibre which can transmit lighthttps://en.wikipedia.org/wiki/Optical_fiber#cite_note-1 from one end to the other. Such fibres find wide usage in fibre-optic communications, where they permit transmission over longer distances and at higher band–widths (data transfer rates) than electrical cables. Fibres are used instead of metal wires since signals travel along them with less loss and are immune to electro-magnetic interference. Fibres are also used for illumination and imaging, and are frequently wrapped in bundles so they can be used to carry light into, or images out of confined spaces, as in the case of a fibre-scope. Specially designed fibres are also used for a variety of other applications, such as fibre optic sensors and fibre lasers. Glass optical fibres are typically made by drawing, while plastic fibres can be made either by drawing or by extrusion. Optical fibres typically include a core surrounded by a transparent cladding material with a lower index of refraction. Light is kept in the core by the phenomenon of total internal reflection which causes the fibre to act as a wave–guide. Fibres which support several propagation paths or transverse modes are called multi-mode fibres, while those which support a single mode are called single-mode fibres (SMF). Multi-mode fibres normally have a wider core diameter and are used for short-distance communication links and for applications where high power are to be transmitted. Single-mode fibres are used for majority of the communication links longer than 1,050 meters.
Optical gas imaging camera – It can be considered a highly specialized version of an infrared or thermal imaging camera. There is a lens, a detector, some electronics to process the signal from the detector, and a viewfinder or screen for the user to see the image produced by the camera. The detectors used for optical gas imaging cameras are quantum detectors which need cooling to cryogenic temperatures (around 70 K or -203 deg C). Mid-wave cameras which detect gases such as methane commonly operate in the 3 micrometers to 5 micrometers range and use an indium antimonide (InSb) detector. Long-wave cameras which detect gases such as sulphur hexa-fluoride tend to operate in the 8 micrometers to 12 micrometers range and use a quantum well infrared photo-detector (QWIP).
Optical gas sensors – Optical sensors’ operation mainly includes controlling, then detection of the beam propagating through the target area where the photons which got detected generate the electrical signals. Frequently utilized optical sensors are, namely fibre-optic gas sensors and photonic-crystal gas sensors. These sensors are based on the principle of the detection of the beam propagation through utilization of devices. Fibre-optic-based sensor measures the modification in optical property (namely, wave-length) and detects the analytes introduced on the sensing polymeric layer by employing optical fibre. These sensors are enriched with excellent sensitivity, stability with respect to the environmental factor as well as longer lifetime. Implementation of optical fibre in the structure causes complications in the miniaturization. Structure of the photonic crystal sensor utilizes the periodic arrangements of dielectric materials with several refractive indexes.
Optical holography – It is a technique which enables an optical wavefront to be recorded and later re-constructed. Holography is best known as a method of generating three-dimensional images but it also has a wide range of other applications. A hologram is made by superimposing a second wavefront (normally called the reference beam) on the wavefront of interest, thereby generating an interference pattern which is recorded on a physical medium. When only the second wavefront illuminates the interference pattern, it is diffracted to recreate the original wavefront. Holograms can also be computer-generated by modelling the two wavefronts and adding them together digitally. The resulting digital image is then printed it onto a suitable mask or film and illuminated by a suitable source to reconstruct the wavefront of interest.
Optically detected magnetic resonance (ODMR) – It is a double resonance technique by which the electron spin state of a crystal defect may be optically pumped for spin initialization and readout. Like electron paramagnetic resonance (EPR), optically detected magnetic resonance makes use of the Zeeman effect in unpaired electrons.
Optical metallography – It is one of three general categories of metallography, entails examination of materials using visible light to provide a magnified image of the micro-structure and macro-structure microscopy (micro-structural examination) involves magnifications of around 50× or higher. Macroscopy (macro-structural examination) involves magnifications of around 50× or lower. Optical microscopy and, is used to characterize structure by revealing grain boundaries, phase boundaries, inclusion distribution, and evidence of mechanical deformation.
Optical metrology – It is a measurement technique which uses light to gather data about the physical properties of objects. This can include measurements of distance, shape, size, surface roughness, and more. Optical metrology has a wide range of applications across different fields e.g., manufacturing and engineering.
Optical microscope – It is frequently referred to as the light microscope. It is a type of microscope which uses visible light and a system of lenses to magnify images of small samples. Optical microscopes are the oldest and simplest of the microscopes. It is a very important instrument for the study of microstructure, despite the evolution of sophisticated electron metallographic instruments.
Optical microscopy – It is the microscopic examination of materials through the optical microscope. The visible part of electromagnetic spectrum is the type of radiation used by optical microscopy.
Optical parametric amplifier (OPA) – It is a laser light source which emits light of variable wave-lengths by an optical parametric amplification process. It is essentially the same as an optical parametric oscillator, but without the optical cavity (i.e., the light beams pass through the apparatus just once or twice, rather than many-many times).
Optical pyrometers – These pyrometers are non-contact temperature measuring devices used for such purposes as flame temperature measurement and for specialized research purposes such as the measurement of piston-ring surface temperatures by sighting through a hole in the cylinder wall. These instruments provide a no-touch means of estimating the surface temperatures of hot objects in the range of 700 deg C to 4,200 deg C, such as metals being hot-worked, liquid metals, gas plasmas, and furnace interiors. Optical pyrometers make use of the fact that all objects at temperatures above 0 K radiate heat in the form of broad-band, electro-magnetic energy. Optical pyrometers operate within the visible spectrum to measure temperatures by comparing the photometric brightness of the heated object against the brightness of a standard source, such as an incandescent tungsten filament. A mono-chromatic filter for the red wavelength radiation (630 nano-meter) is used to support the operation. The comparison of the brightnesses is dependent on the sensitivity of the human eye (on manual versions) to distinguish the brightness difference between two surfaces of the same colour. The brightness comparison is made adjusting the current through the filament of the standard brightness source until its brightness becomes equal to that of the measured object. It is possible to get measurements with accuracy better than 1%. There are also commercial automatized versions of optical pyrometers.
Optical rotation – It is also known as polarization rotation or circular birefringence. It is the rotation of the orientation of the plane of polarization about the optical axis of linearly polarized light as it travels through certain materials. Circular birefringence and circular dichroism are the manifestations of optical activity. Optical activity occurs only in chiral materials, those lacking microscopic mirror interactions symmetry.
Optical spectrometry – It refers to the analysis of a light spectrum separated by wave-lengths. It can be of two types – absorption or emission. An atomic optical / emission spectrometer (AES / OES) is one which analyses an optical (light) spectrum emitted by an excited sample. The excitation can be by a number of means, such as application of a spark, plasma, and flame etc. The term ‘optical emission spectrometry’ is now almost ubiquitously used to refer to the arc-spark optical emission spectrometry technique.
Optics – It is the branch which studies the behaviour and properties of light, including its with matter and the construction of instruments that use or detect it. Optics normally describes the behaviour of visible, ultra-violet, and infra–red light. Light is a type of electro-magnetic radiation, and other forms of electro-magnetic radiation such as X-rays, micro-waves, and radio waves show similar properties. Majority of the optical phenomena can be accounted for by using the classical electro-magnetic description of light, however complete electro-magnetic descriptions of light are frequently difficult to apply in practice. Practical optics is normally done using simplified models. The most common of these, geometric optics, treats light as a collection of rays that travel in straight lines and bend when they pass through or reflect from surfaces. Physical optics is a more comprehensive model of light, which includes wave effects such as diffraction and interference which cannot be accounted for in geometric optics.
Optimal control – It is the branch of control theory studying optimization of a control system to fit some optimization criterion.
Optimal design – It is normally considered as the design process which seeks the ‘best’ possible solution(s) for a mechanical structure, device, or system, satisfying the requirements and leading to the ‘best’ performance, through optimization techniques. It also refers to the design points that best satisfy objective(s) which are in contrast to non-optimal design. A formal definition of design is ‘design establishes and defines solutions to pertinent structures for problems not solved before, or new solutions to problems which have previously been solved in a different way’. Optimal indicates a searching and decision-making process which is needed to determine the best possible design alternatives. Optimization techniques are used to evaluate the trade-off among design alternatives and determine the best one(s).
Optimization – It is the action of making the best or most effective use of a situation or resource. It is the process of searching for the best combination of design parameters.
Optimization, engineering – It is the process of finding the most effective or favourable value or condition. The purpose of optimization is to achieve the ‘best’ design relative to a set of prioritized criteria or constraints. Design optimization suggests that for a given set of possible designs and design criteria there exists a single design which is best or optimal.
Orange peel – It is a surface roughening in the form of a pebble-grained pattern which occurs when a metal of unusually coarse grain size is stressed beyond its elastic limit. It has the appearance of an orange skin. It is also called pebbles and alligator skin. In painting, it is a pebbled film surface caused by too rapid drying after spraying, by failure of the coating material to show the desired leveling effects, or by uneven flow (application) in roller coating techniques. In porcelain enamel, it is a surface condition characterized by an irregular waviness that resembles an orange skin in texture, which is sometimes considered a defect.
Orbit – It is the fixed path on which electron moves or revolves around the atom’s nucleus. Furthermore, an orbit is a simple planar representation of a particular electron. Moreover, it is the path whose establishment takes place because of a circular motion as the electron revolves around the nucleus.
Orbital – It is a region of an atom or molecule in which one or more electrons can be found. The term can refer to either an atomic orbital or a molecular orbital.
Orbital forging – It is a process in which the work-piece is pressed between a flat anvil and a swiveling (rocking) die with a conical working face. The platens move toward each other during forging.
Orbital maneuvering system (OMS) – It is a key component of spacecraft propulsion, responsible for making orbital adjustments and maneuvers during spaceflight.
Orbital motion – It is the motion of an object in orbit around another object and an orbit is the curved path of an object around another object in space. An orbital motion is a motion over a repeating path taken by an object around another object. In general, orbits are elliptical.
Orbital scanning – It is an angle probe technique which is used to get information about the form of discontinuity previously located. The scanning is made around the discontinuity.
Order (in x-ray reflection) – It is the factor ‘n’ in the Bragg equation. In x-ray reflection from a crystal, the order is an integral number that is the path difference measured in wave-lengths between reflections from adjacent planes.
Order-disorder transformation – It is a phase change among two solid solutions having the same crystal structure, but in which the atoms of one phase (disordered) are randomly distributed. In the other, the different kinds of atoms occur in a regular sequence upon the crystal lattice, i.e., in an ordered arrangement.
Ordered crystal structure – It is a structure held together by atoms, ions, or molecules arranged in a highly ordered 3-dimensional arrangement is a crystal structure. Crystal structure can be thought of as the highest level of ordering which can exist in a solid material. This arrangement can be referred to as the crystal lattice structure.
Ordered structure – Ordered structures, frequently called ‘superlattices’, result from the ability of the atoms within several alloy phases to arrange themselves into specific configurations. It is the crystal structure of a solid solution in which the atoms of different elements seek preferred lattice positions.
Order hardening – It is a low-temperature annealing treatment which permits short-range ordering of solute atoms within a matrix, which greatly impedes dislocation motion.
Ordinal logistic regression – It is a logistic regression model for a study end point with more than two values where the values also represent rank order on the characteristic of interest.
Ordinal scale – The ordinal scale of measurement occurs when a random variable can take on ordered values, but there is not an even interval between levels of the variable. Examples of ordinal variables include the choice between three automobile brands, where the response is highly desirable, desirable, and least desirable. Ordinal variables provide the second lowest quantity of information compared to other scales of measurement.
Ordinal variable – An ordinal variable is a categorical variable in which the categories have an obvious order, e.g. (strongly disagree, disagree, neutral, agree, strongly agree), or (dry, trace, light rain, heavy rain).
Ordinary differencing – It consists of creating a transformed series by subtracting the immediately adjacent observations.
Ordinary differential equation – It is a differential equation dependent on only a single independent variable. As with any other differential equation, its unknown(s) consists of one (or more) function(s) and involves the derivatives of those functions. The term ‘ordinary is used in contrast with partial differential equations which can be with respect to more than one independent variable, and, less commonly, in contrast with stochastic differential equations where the progression is random.
Ordinary least squares (OLS) – It is a means of estimating coefficients in linear regression and ANOVA models which depends on finding the estimates which minimize the sum of squared prediction errors.
Ordinary portland cement (OPC) – It is available in several grades, namely 33-grade, 43-grade, and 53-grade etc. If 28-day strength is not less than 33 mega pascals (MPa) then it is called cement of 33-grade. If 28-day strength is not less than 43 MPa then it is called cement of 43-grade. Use of higher-grade cement offers several advantages and makes stronger concrete. Although higher grade cement is little costlier than the low-grade cement, it offers 10 % to 20 % saving in the cement consumption and it also offers several other hidden advantages. One of the most important advantages is the faster rate of development of the strength. Ordinary portland cement is used for the ordinary works. This type of cement is used in constructions where there is no exposure to sulphates in the soil or ground-water. The lime saturation factor (LSF) for this cement [(CaO-0.7 SO3)/(2.8 SiO2 + 1.2 Al2O3 + 0.65 Fe2O3)] is limited between 0.66-1.02. Here each oxide denotes the percentage of the oxide in cement composition.
Ore – It is a natural mineral which can be mined and treated for the extraction of any of its components, metallic or otherwise, at a profit. Ore is a mixture of ore minerals and gangue from which at least one of the metals can be extracted at a profit.
Ore-body – It is a natural concentration of valuable material which can be extracted and sold at a profit.
Ore characteristics – It includes material specification, feed (input) size, material friability, and material abrasiveness of the ore.
Ore deposits – These are rock volumes containing selected elements in sufficient concentration and quantity that they can be extracted economically. The formation of ore deposits, like all other geologic processes, is the consequence of multiple events spread through geologic time. Two groups of ore deposits can be established syngenetic and epigenetic depending on their formation time relationship to the rocks associated with them. Syngenetic ore deposits are formed at the same time as the associated rocks as in magmatic segregation during the orthomagmatic stage of consolidation of magma or during precipitation of sedimentary rocks. Formation of ore deposits in gossans and laterites because of in situ residual gossans are also considered as syngenetic because as the new rock (laterite, bauxite, kaolinite, or duricrust) is formed it is at that same time the ore deposit is formed. The epigenetic mineral deposits are formed later after the enclosing or host rocks have been formed in filled or opened fissures in the country rocks and such ore bodies are called lodes or veins. These vein and lode deposits occur as in interstices of the country where the rock forms first and then ores form as impregnations or replacements of the country rock. In contact metamorphism mineral deposits form irregular ore bodies on the margins of metamorphosed rocks. In sedimentary rocks epigenetic processes, ore deposits are formed because of weathering and deposition of detrital sedimentary rocks in basins where placer deposits are emplaced.
Ore dressing – It consists of physical and chemical concentration of raw ore into a product from which a metal can be recovered at a profit.
Ore pass – It is the vertical or inclined passage for the downward transfer of ore connecting a level with the hoisting shaft or a lower level.
Ore reserve – An Ore reserve is the economically mineable part of a Measured and / or Indicated Mineral resource. It includes diluting materials and allowances for losses, which can occur when the material is mined or extracted and is defined by studies at Pre- Feasibility or Feasibility level as appropriate that include application of the Modifying factors. Such studies demonstrate that, at the time of reporting, extraction can reasonably be justified.
Ore reserves – It is the calculated tonnage and grade of mineralization which can be extracted profitably. Ore reserves are classified as possible, probable, and proven as per the level of confidence which can be placed in the data.
Ore-shoot – It is the portion, or length, of a vein or other structure which carries sufficient valuable minerals to be extracted profitably.
Organic – It means being or composed of hydrocarbons or their derivatives. It is the matter originating in plant or animal life, or composed of chemicals of hydrocarbon origin, either natural or synthetic.
Organic acid – It is a chemical compound with one or more carboxyl radicals (COOH) in its structure; examples are butyric acid, CH3(CH2)2COOH; maleic acid, HOOCCH-CHCOOH; and benzoic acid, C6H5COOH. It is an organic compound with acidic properties.
Organic air pollutants – These are sometimes divided according to particulate organic compounds (POCs) and volatile organic, although there are some species which are actually distributed between the particulate and gaseous phases. The emission of unburned or partially burned fuel from combustion processes and escape of organic vapours from industrial operations are the major anthropogenic sources of organic air pollutants. There are a large number of volatile organic compounds. They include hydro-carbons (CxHy) and also other organic chemicals which are emitted from a very wide range of sources, including fossil fuel combustion, industrial activities, and natural emissions from vegetation and fires. Volatile organic compounds are an important outdoor air pollutant. In this field they are frequently divided into the separate categories of methane (CH4) and non-methane volatile organic compounds (NMVOCs). Major anthropogenic sources of methane include natural gas production and use, coal mining, livestock, and rice paddies. Methane, the simplest and most long-lived volatile organic compounds is an extremely efficient greenhouse gas which contributes towards increased global warming. Other hydrocarbon volatile organic compounds are also significant greenhouse gases through their role in creating ozone (O3) and in prolonging the life of methane in the atmosphere, although the effect varies depending on local air quality. Within the non-methane volatile organic compounds, the aromatic compounds benzene (C6H6), toluene (C7H8), and xylene (C8H10) are suspected carcinogens. The compound 1, 3-butadiene (C4H6) is another dangerous compound which is frequently associated with industrial uses.
Organic base – It is an organic compound which acts as a base. Organic bases are normally, but not always, proton acceptors. They normally contain nitrogen atoms, which can easily be protonated. For example, amines or nitrogen-containing heterocyclic compounds have a lone pair of electrons on the nitrogen atom and can thus act as proton acceptors.
Organic bond – It consists of bond of organic nature with bonding or hardening at ambient temperature or at a higher temperature.
Organic chemistry – It is the study of the structure, properties, composition, reactions, and preparation of carbon-containing compounds.
Organic coating – It is a type of coating formed by carbon-based polymeric chains derived from natural (vegetable, animal) or synthetic matter. Solid, adhesive, and cohesive organic coatings can be found in the form of paints, varnishes, and lacquers.
Organic compound – It is defined as a chemical compound which contains a carbon–hydrogen or carbon-carbon bond, others consider an organic compound to be any chemical compound which contains carbon. For example, carbon-containing compounds such as alkanes (e.g., methane CH4) and its derivatives are universally considered organic, but several others are sometimes considered inorganic, such as halides of carbon without carbon-hydrogen and carbon-carbon bonds (e.g., carbon tetra-chloride, CCl4), and certain compounds of carbon with nitrogen and oxygen (e.g., cyanide ion CN-, hydrogen cyanide HCN, chloro–formic acid ClCO2H, carbon di-oxide CO2, and carbonate ion (CO3)2−.
Organic contaminants – It consists of carbon-based chemicals, such as solvents and pesticides, which can get into water through run-off from discharge from factories. Organic contaminants include herbicides, pesticides, and plant and animal tissues, and are normally expected to cause adverse impacts on the environment. Trace levels of organic contaminant residues present in the soil, water, air, and sometimes food can result in harmful effects for human and environmental health.
Organic emissions – Organic emissions from primary steel operations can include benzene, toluene, xylene, solvents, PAHs, dioxins and phenols. The scrap steel used as raw material can include a variety of these substances, depending on its source and the way it had been used (e.g., paint and other coatings, other metals, and lubricants). Not all of these organic pollutants are captured by the conventional gas cleaning systems.
Organic insulation materials – These materials are derived from a petro-chemical or renewable feedstock (bio-based). Almost all of the petro-chemical insulation materials are in the form of polymers and are cellular. A material is cellular when the material’s structure consists of pores or cells. On the other hand, several plants contain fibres for their strength. Hence, almost all the bio-based insulation materials are fibrous (except expanded cork, which is cellular). Examples of petro-chemical materials (oil / coal-derived) are expanded poly-styrene (EPS), extruded poly-styrene (XPS), poly-urethane (PUR), phenolic foam, and poly-iso-cyanurate foam (PIR). Examples of renewable materials (plant / animal-derived) are cellulose, cork, wood-fibre, hemp fibre, flax wool, sheep wool, and cotton insulation.
Organic linings – These linings are made of organic substances (i.e., chemically speaking these are complex carbon molecules) such as cellulose and phenolic resin. Organic linings are a separate category of lining distinct from other types of linings made out of different materials such as semi-metallic, metallic and carbon.
Organic liquids – These are used in a wide variety of industrial applications. They can be characterized as liquids which consist of one or more carbon atoms joined to other atoms through covalent bonds. Common atoms included in organic molecules are hydrogen, oxygen, nitrogen, sulphur, and halogens. Both the rate and yield of certain reactions have been found to greatly increase when performed in organic liquids. Hence, they are widely used in the chemical process industry for synthesis. With the increase in the use of organic liquids, increases in observed corrosion problems associated with the exposure of materials to them have also occurred. In some cases, failures involve an unacceptably large loss of metal or degradation of material properties.
Organic matrix composite (OMC) – It is a composite material composed of a variety of short or continuous fibres bound together by a matrix of organic polymers. Organic matrix composites are designed to transfer loads between fibres of a matrix. Some of the advantages with organic matrix composites include their light weight, high resistance to abrasion and corrosion, and high stiffness and strength along the direction of their reinforcements.
Organic matter – It is the compounds containing carbon frequently derived from living organisms.
Organic maturation – It is the process of turning peat into coal.
Organic pollutants – Organic pollutants include proteins, carbo-hydrates, fats and oils, dyestuffs, organic acids, phenols, detergents and organo-pesticides. Organic pollutants are organic compounds which are resistant to environmental degradation through chemical, biological, and photolytic processes. Because of this property of the organic pollutants, these pollutants have potential adverse impacts on the human health and the environment. Organic pollutants can be further divided into three categories namely (i) oxygen demanding wastes, (ii) synthetic organic compounds, and (iii) oils and grease.
Organic Rankine cycle (ORC) – The organic Rankine cycle operates similar to the steam Rankine cycle, but uses an organic working fluid instead of steam. Alternatives include silicon oil, propane, halo-alkanes (e.g. freons), iso-pentane, iso-butane, p-xylene, and toluene, which have a lower boiling point and higher vapour pressure than water. This allows organic Rankine cycle to operate with significantly lower waste heat temperatures. The most appropriate temperature range depends on the fluid used, as fluids’ thermo-dynamic properties influence the efficiency of the cycle at various temperatures. In comparison with water vapour, the fluids have a higher molecular mass, enabling compact designs, higher mass flow, and higher turbine efficiencies. However, since organic Rankine cycle functions at lower temperatures, the overall efficiency is low and depends on the temperature of the condenser and evaporator. While the efficiency is lower than a high temperature steam power plant, it is important to remember that low temperature cycles are inherently less efficient than high temperature cycles. Limits on efficiency can be expressed according to Carnot efficiency which is the maximum possible efficiency for a heat engine operating between two temperatures. A Carnot engine operating with a heat source at 150 deg C and rejecting it at 25 deg C is only about 30 % efficient. In this light, a low efficiency in the range of 10 % to 20 % in case of organic Rankine cycle is a substantial percentage of theoretical efficiency, especially in comparison to other low temperature alternatives, such as piezoelectric generation, which are only 1 % efficient. Although the economics of organic Rankine cycle, heat recovery need to be carefully analyzed for any given application, it is a useful alternative in those industries which do not have in-house use for additional process heat or no neighbouring plants which can make economic use of the heat.
Organic zinc-rich paint – It consists of coating containing zinc powder pigment and an organic resin.
Organic solvents – It is a common designation for a large group of more than 200 chemical compounds capable of dissolving non-water-soluble materials such as fats, oils, waxes, resins, rubber, asphalt, cellulose filaments, and plastic materials. Compounds from several different chemical groups can serve as solvents. Organic refers to compounds which contain carbon bonds and in which at least one carbon atom is covalently linked to an atom of another type (normally hydrogen, oxygen, or nitrogen). Organic solvents contain at least one carbon and one hydrogen molecule. Aliphatic compounds form a chain, whereas aromatic compounds form a six-carbon ring. The hydrogen group can be substituted by some other element such as a hydroxyl group in alcohols or a carbonyl group in ketones and esters. Halogenated hydro-carbons contain a substituted halogen element, often a chloride. As a group, they share few physical features and even fewer chemical properties.
Organization – It is a body built for a collection of individuals who join together to achieve some common goals and objectives bounded by legal entities. Organizations are frequently referred to as a company, institution, association, and government body etc. They follow certain legal procedures like business registration, tax identification, and maintaining corporate book records.
Organizational agility – It is the ability of the organization to manage continuous, rapid and sustainable change. It is the capacity and flexibility of the organization to be consistently adaptable to market and environmental changes with rapidness and speed. It is the efficiency with which the organization can respond to nonstop change. It is the organizational ability to exploit both revenue enhancing and cost cutting opportunities within its core business more quickly, effectively, and consistently than its competitors. It makes the organization to operate at the speed with which the opportunities are getting created. In the fast-changing complex environment of the present-day organizational agility is the key differentiator between organizations.
Organizational behaviour – It deals with employee attitudes and feelings, including job satisfaction, organizational commitment, job involvement, and emotional labour.
Organizational competencies – These are the competencies needed in the organization so that it can excel and remain competitive in the market. The competencies provide an inventory of expected behaviours, skills and attitudes which lead to the successful performance of the organization. They depend heavily on the competencies of the employees of the organization. Organizational competencies, in the most general terms, are those ‘things’ which the employees of the organization are to demonstrate to be effective in their job, role, function, task, or duty. These ‘things’ include (i) job-relevant behaviour (what the employees say or do which result in good or poor performance), (ii) motivation (how the employees feel about a job, organization, or geographic location), and (iii) technical knowledge / skills (what the employees know / demonstrate regarding facts, technologies, their professions, procedures, jobs, and the organization, etc.).
Organizational culture – It means work related activities and meanings attached to such activities in the framework of norms and values of the organization. These activities, norms, and values are normally contextualized in the organization. The organizational culture normally focuses on employee centricity, teamwork and continuous process improvement. It is also expressed in terms of values, ideologies of the organization. It further makes the foundation of integrity, thoughts and actions of the employees working there. The culture of the organization is to be developed to support continuous improvement, improve employees’ style of performing their job and thus develop quality awareness. Organizational culture has influence on employee work behaviour as a result on the acceptable behaviours and attitudes to different jobs in the organization. Organizational culture is a major determinant of the employees’ efficiency and effectiveness in carrying out their jobs. Hence, organizational culture determines of how employees perform or behaves in their job.
Organization discipline – It is the force which prompts individuals or groups to observe rules, regulations, standards, and procedures deemed necessary for the organization. It means orderly and systematically conducting the different operations of the organization by the employees who strictly adhere to the necessary procedures. The employees work together as a team and cooperate harmoniously with each other so as to achieve organizational goal and objectives as well as mission and vision and they truly understand that the individual and group aims and desires are to match so as to achieve organizational success. Organizational discipline is the force or fear of a force which deters the employee or a group of employees from doing things which are detrimental to the accomplishment of the goal and objectives of the organization. In other words, organizational discipline is the orderly conduct by the employees of the organization who adhere to its rules and regulations since they desire to cooperate harmoniously in forwarding the end which the organization has in view.
Organizational environment – It is defined as a set of characteristics which describe the organization and distinguish it from other organizations within a given time period affecting behaviour of the employees therein. These characteristics affect the functional behaviour of the employees, their trends and motives. These characteristics basically interconnect the internal work environment in the organization and make it a distinct feature of the organization. Organizational environment also differentiates the organization with other organizations. It also provides relative stability to the organization.
Organizational ethics – It is a broad and dynamic concept comprising ethical environment, levels of trust, moral awareness, and ways of acting which ensure that a shared set of values which promotes the common good becomes the prevailing culture of the organization. It includes both the corporate values and the financial practices of the organization. They relate to all aspects of the organization including mission, vision, governance, and leadership. It includes not only culture and trust, but also processes, outcomes, and character and denotes a way of acting, and not a code of principles. It is at heart, pumping blood which perfuses the entire organization with a common sense of purpose and a shared set of values. It refers to the attempt of the organization to define its values, recognize values which can cause tension, seek best solutions to these tensions, and manage the operations to maintain the values. It constitutes the principles and standards which determine acceptable conduct in the organization. It relates to actions, which are characterized by honesty, integrity, morality, and good management practices.
Organizational learning – It is the ability of an organization to gain insight and understanding from experience through experimentation, observation, analysis, and a willingness to examine both successes and failures. It denotes a change in organizational knowledge. It typically adds to, transforms, or reduces organizational knowledge. It changes in the state of knowledge. It involves knowledge acquisition, dissemination, refinement, creation and implementation. It is the ability to acquire diverse information and to share common understanding so that this knowledge can be exploited for the ability to develop insights, knowledge, and to associate among past and future activities.
Organizational mission – It is related to goals, and refers to the domineering purpose of the organization. Mission is frequently stated in terms of the seemingly simple but challenging statement which defines purpose of the organization. Hence, mission statement enables management to emphasize on the essential area of the organizational strategy.
Organizational objectives – These are described in a clear-cut and quantifiable statement of the organizational goals over the selected time period. This can refer to different targets which the organization desires to achieve in the selected time period. Objectives introduce discipline to strategy. They state what the organization is going to accomplish in the selected time period.
Organizational performance – It is defined as the outcome which indicate or reflect the organization efficiencies or inefficiencies in term of corporate image, competencies and financial outcomes. It is concerned with the effectiveness, productivity, efficiency, excellence, or quality of the organization. It means the transformation of inputs into outputs for achieving certain outcomes. With regards to its content, organizational performance informs about the relation between minimal and effective cost (economy), between effective cost and realized output (efficiency), and between output and achieved outcome (effectiveness). Organizational performance is the process to enhance both the effectiveness of the organization and the well-being of its employees through planned interventions. It refers to the actual output or results of the organization as measured against its intended outputs, goals and objective. There are four types of organizational performance measures namely (i) human resource outcomes, (ii) organizational outcomes, (iii) financial accounting outcome, and (iv) capital market outcomes
Organizational policies and procedures – These reflect their vision, values, and culture as well as the needs of their employees. Organizational policy is a statement of principles, rules, and guidelines which the organization follows in order to achieve a desired outcome. The policy is a set of general guidelines which outline the organization’s plan for tackling an issue. It exists to communicate the organizational point of view to its employees and to ensure that actions carried out at the organization take place within the defined boundaries of the policies and procedure. Policies and procedures communicate the connection between the organization’s vision and values and its day-to-day operations. A procedure explains a specific action plan for carrying out a policy. It is a set of actions which an employee takes to complete an activity within the confines of an organizational policy. It exists as a reference for employees to understand their roles and responsibilities. Procedures tell employees how to deal with a situation and when. Using policies and procedures together gives employees a well-rounded view of the organization.
Organizational strategy – It consists of the direction and scope of the organization over the long-term which helps it to attain benefit through its configuration of resources within a challenging environment aimed at meeting market needs and fulfilling stake-holder expectations. It constitutes large scale action plans for relating with the environment in order to accomplish long-term goals. It is a form of actions and resource apportionments designed to accomplish the goals of the organization. It consists of the determination of long-term goals and objectives, the adoption of courses of action and associated allocation of resources needed to achieve goals. Organizational strategy is an indispensable tool for the success of an organization, since as it helps the organization to be more proactive than reactive in moulding its own future. It makes the organization to initiate and affect activities so that it can exert control over its own purpose.
Organizational structure – It refers to the relations between the components of an organization as a whole. The organization structure can be considered mostly of two types namely (i) physical, and (ii) social. Physical structure refers to the relations between physical elements of organizations as buildings and geographical places in which the works are carried out. Social structure refers to the relations between social elements as people, positions and organizational units (e.g. departments and sectors). It is the social structure which is normally referred to as ‘organizational structure’. Organizational structure refers to the model of internal relations in the organization. Through it are clarified the (i) power, relations and reporting, (ii) formal communication channels, and (iii) responsibility and decision-making delegation. Organizational structure is the framework of the relations on jobs, systems, operating process, people and groups making efforts to achieve the goals. It is a set of methods dividing the task to determine the duties and coordinates them. Through the organizational structure, the organizational activities are divided, organized and coordinated. The organization creates the structure to coordinate the activities of work factors and control the employees’ actions. The organizational structure determines the way the job tasks are formally divided, grouped, and coordinated within the organization. When the organizational management develops or changes the structure, it is engaged in organizational design, a process which involves decisions about six key elements namely (i) work specialization, (ii) departmentalization, (iii) chain of command, (iv) span of control, (v) centralization and decentralization, and (vi) formalization.
Organizational vision – It is connected to organizational goals, and refers to the anticipated future state of the organization. Vision is an aspiration which can help mobilize the energy and passion of the employees. It states what the organization want to achieve.
Organizing – It is the function of management which follows planning. It is the process of establishing orderly uses for all resources within the management system of the organization. It is a function in which the synchronization and combination of human, physical, financial, and information resources takes place for the achievement of the results. Organizing function is necessary since it facilitates administration as well as the functioning of the organization.
Organo-metallic chemical vapour deposition (CVD) – It is an advanced technique in materials science used for the precise deposition of organo-metallic materials on substrates. This method has wide applications in the production of thin films, coatings and nano-structures. In organo-metallic chemical vapour deposition, an organo-metallic compound is used as the starting material. This compound normally contains metal atoms that carry organic ligands. During the chemical vapour deposition process, the organo-metallic compound is transported in a gas stream and passed over the substrate to be coated. By heating the substrate, the organo-metallic molecules are dissociated and the metal atoms are deposited on the substrate surface, creating a thin layer. Organo-metallic chemical vapour deposition offers precise control over the thickness and composition of the deposited layers. By selecting specific organo-metallic compounds, different metals and compound types can be deposited, enabling a wide range of applications. This technique is used in particular in the semi-conductor industry, micro-electronics and the production of thin films for solar cells.
Orientation – It is the alignment of the crystalline structure in polymeric materials in order to produce a highly aligned structure. Orientation can be accomplished by cold drawing or stretching in fabrication. In crystals, orientation is the arrangements in space of the axes of the lattice of a crystal with respect to a chosen reference or coordinate system.
Orientation distribution function (ODF) – It is sometimes also called orientation density function. It is a function on the orientation space which associates to each orientation ‘g’ the volume percentage (V) of crystals in a poly-crystalline sample which are in this specific orientation. Formally, this is frequently expressed by the formula ODF(g) = (1/V) x [(dV(g)/dg].
Oriented materials – These are the materials, particularly amorphous polymers and composites, whose molecules and / or macro-constituents are aligned in a specific way. Oriented materials are anisotropic. Orientation can normally be divided into two classes, uniaxial and biaxial.
Orifice – It is the opening from the whirling chamber of a mechanical atomizer or the mixing chamber of a steam atomizer through which the liquid fuel is discharged. It is also a calibrated opening in a plate, inserted in a gas stream for measure velocity of flow.
Orifice gas (plasma arc welding and cutting) – it is the gas which is directed into the torch to surround the electrode. It becomes ionized in the arc to form the plasma and issues from the orifice in the torch nozzle as the plasma jet.
Orifice plate – It is a device which used for measuring flow rate, for reducing pressure, or for restricting flow. In the latter two cases, it is frequently called a restriction plate. An orifice plate is a thin plate with a hole in it, which is normally placed in a pipe. When a fluid (whether liquid or gaseous) passes through the orifice, its pressure builds up slightly upstream of the orifice, but as the fluid is forced to converge to pass through the hole, the velocity increases and the fluid pressure decreases. A little downstream of the orifice the flow reaches its point of maximum convergence, the ‘vena contracta’ where the velocity reaches its maximum and the pressure reaches its minimum. Beyond that, the flow expands, the velocity falls and the pressure increases. By measuring the difference in fluid pressure across tappings upstream and downstream of the plate, the flow rate can be obtained from Bernoulli’s equation using coefficients established from extensive research.
Original crack size (ao) – It is the physical crack size at the start of testing.
Original resource – It is the amount of a resource before production.
Orogeny – It is a period of mountain-building characterized by the folding of a portion of the earth’s crust.
Orphan source – It is a radioactive source which is not under the control of a licensee.
Orsat – It is a gas-analysis apparatus in which certain gaseous constituents are measured by absorption in separate chemical solution.
Orsat analyzer – It is an atmosphere analysis device in which gases are absorbed selectively (volumetric basis) by passing them through a series of preselected solvents.
Orthochromatic filter It consists of a colour filter which modifies the illumination quality reaching the film so that the brightness of coloured objects is relatively the same in the resultant black-and-white positive.
Orthogonal – The term is used to describe lines which meet at a right angle, it also describes events which are statistically independent, or do not affect one another in terms of outcome.
Orthogonal array – A balanced fractional factorial type of design of experiments. It is used as a key part of robust design to determine the effect each factor has on the mean and the variability in an experiment where several factors are involved. It consists of a ‘table’ (array) whose entries come from a fixed finite set of symbols (for example, {1,2,…,v}, arranged in such a way that there is an integer ‘t’ so that for every selection of ‘t’ columns of the table, all ordered t-tuples of the symbols, formed by taking the entries in each row restricted to these columns, appear the same number of times. The number ‘t’ is called the strength of the orthogonal array.
Orthogonality condition – It is the assumption that the experimental- error term in a statistical model is uncorrelated with the explanatory variables in the model.
Orthographic drawing – It is a drawing in which a three-dimensional object is represented in two dimensions. This is done making multiple two-dimensional drawings of the object, viewed from different angles.
Orthographic projection – It is a means of representing three-dimensional objects in two dimensions. Orthographic projection is a form of parallel projection in which all the projection lines are orthogonal to the projection plane, resulting in every plane of the scene appearing in affine transformation on the viewing surface. The obverse of an orthographic projection is an oblique projection, which is a parallel projection in which the projection lines are not orthogonal to the projection plane.
Orthographic views – These are two-dimensional views used to define a three-dimensional model. More than one orthographic view is needed to define a model unless the model is of uniform thickness. Standard practice calls for three orthographic views, a front, top, and side view, although more or fewer views can be used as needed. The International Organization for Standardization (ISO) standard ISO 5456-2 specifies the orthographic projection methods.
Orthorhombic – It consists of having three mutually perpendicular axes of unequal lengths.
Orthorhombic crystal system – It is one of the seven crystal systems. Orthorhombic lattices result from stretching a cubic lattice along two of its orthogonal pairs by two different factors, resulting in a rectangular prism with a rectangular base (‘a’ by ‘b’) and height (‘c’), such that ‘a’, ‘b’, and ‘c’ are distinct. All three bases intersect at 90-degree angles, so the three lattice vectors remain mutually orthogonal.
Orthotropic – It means having three mutually perpendicular planes of elastic symmetry.
Ortho-xylene – It is an aromatic hydrocarbon with the formula C6H4(CH3)2, with two methyl substituents bonded to adjacent carbon atoms of a benzene ring (the ortho configuration). It is a constitutional isomer of m-xylene and p-xylene, the mixture being called xylene or xylenes. Ortho-xylene is a colourless slightly oily flammable liquid.
Oscillating die press – It is a small high-speed metal forming press in which the die and punch move horizontally with the strip during the working stroke. Through a reciprocating motion, the die and punch return to their original positions to begin the next stroke.
Oscillating piston totalizers – In this type of totalizer, the oscillating piston in a cylindrical housing a hollow cylinder, oscillates eccentrically. In this manner it transports defined volumes. The stationary outer cylinder is also the housing, in which a dividing wall and a guide ring are mounted. The dividing wall on the bottom of the housing provides the boundary between the inlet and outlet openings. The bearing for the oscillating piston is mounted in the sleeve and is guided along the dividing wall. Openings for filling and draining are located in its base. The movement of the piston bearing is transmitted to an indicator using a magnet and follower arrangement. In a direct piston totalizer, the magnetic coupling is not utilized and the rotary motion of the piston is transmitted directly from the piston to the totalizer. Since the oscillating piston wears rapidly, proper material selection is very important. Various materials are available such as gray cast iron, bronze, hard rubber, carbon and plastics. For high temperature operation an intermediate spacer is used to provide additional separation from the totalizer. Oscillating piston totalizers are especially used for water and oil measurement.
Oscillating screens – They are suitable for wet and dry materials, particles and chips. They provide for a precise classification of material into different fractions, which are then sent to further processing. The principle of operation is based on the oscillation of a sifting case equipped with several sifting decks located inside. The vibration intensity is adjustable by means of counter-weights. The quantity of the screening fractions depends upon the number of the sifting decks, while the obtainable particle size depends upon the type and mesh size of the single screens. The relative motion between the sieve and the particle mass can be gyratory, with a vertical rocking oscillation super-imposed on the circular motion or oscillating in a straight-line, simple harmonic motion.
Oscillation – It is the repetitive or periodic variation, typically in time, of some measure about a central value (frequently a point of equilibrium) or between two or more different states. Familiar examples of oscillation include a swinging pendulum and alternating current. Oscillations can be used in physics to approximate complex interactions, such as those between atoms. Oscillations occur not only in mechanical systems but also in dynamic systems in virtually every area of science.
Oscillation marks – These marks appear as grooves perpendicular to the casting direction. They are typically 0.1 millimeter to 1 millimeter deep. The oscillation marks can work as initiation point for cracks and beneath them there is a zone with higher risk for inclusions, pores, and segregation.
Oscilloscope – It is an instrument for graphically displaying a wave-form as a function of time.
Osmium – It is a chemical element; it has symbol Os and atomic number 76. It is a hard, brittle, bluish-white transition metal in the platinum group which is found as a trace element in alloys, mostly in platinum ores. Osmium is the densest naturally occurring element. When experimentally measured using X-ray crystallography, it has a density of 22.59 grams per cubic meter. Manufacturers use its alloys with platinum, iridium, and other platinum-group metals to make fountain pen nib tipping, electrical contacts, and in other applications that require extreme durability and hardness.
Osmosis – It is the spontaneous net movement or diffusion of molecules of a solvent (e.g., water) through a selectively permeable membrane separating two solutions with different concentrations of dissolved solutes, in the direction that tends to equalize the solute concentrations on the two sides, i.e., from the more dilute solution to the more concentrated solution, or, equivalently, from a region of high-water potential to a region of low water potential. Since the solute is unable to cross the membrane, the tendency towards equilibration compels the solvent to cross the membrane instead. This continues until an equilibrium is reached, where neither side of the membrane is more or less concentrated than the other.
Osmotic pressure – It is the minimum pressure which needs to be applied to a solution to prevent the inward flow of its pure solvent across a semi-permeable membrane. It is also defined as the measure of the tendency of a solution to take in its pure solvent by osmosis. Potential osmotic pressure is the maximum osmotic pressure which can develop in a solution if it is separated from its pure solvent by a semi-permeable membrane.
Osprey process – It converts a stream of molten metal into a particulate spray by gas atomization, which then produces a preform shape by impingement directly on to a collector. Molten metal poured into a tundish is atomized by a mixture of argon and nitrogen gas. The particulate droplets are sprayed onto a preform die. The established preform then undergoes hot working processes to result in its final shape.
Oudin coil – It is an early form of high-voltage induction coil which is identical in principle to a Tesla coil except for being constructed essentially as an auto-transformer.
Outage – It is a period when a service or an application is not available or when equipment is not operational. It can be planned or unplanned.
Outage, power– A power outage (also called a power cut, a power out, a power failure, a power blackout, a power loss, or a blackout) is the loss of the electrical power network supply to an end user.
Out-crop – It is an exposure of rock or mineral deposit which can be seen on surface, that is, not covered by soil or water.
Outcome – It is the result of either planned or unplanned actions. For planning purposes, ‘outcomes’ are the desired end-point and are to guide the development and implementation of related programmes. Outcomes can be broad and long-term in nature or focused. They are used in both direction setting and performance measurement.
Outer noise – It 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.
Outer sheath, electrical cable – Outer sheaths are made of black poly-vinyl chloride compound, which protect the armour material from corrosion. This PVC compound is applied by extrusion method. Outer sheath is applied over the non-magnetic metallic tape covering the insulation or over the non-magnetic metallic part of insulation screening in case of unarmoured single core cables and over the armouring in case of armoured cables.
Outfall – It is the point at which a pipe or channel discharges to a water body.
Out-gassing – It is the release of solvents and moisture from composite parts under vacuum. It also occurs during the normal curing process under vacuum. It is sometimes called off-gassing, particularly when in reference to indoor air quality. It is the release of a gas which has been dissolved, trapped, frozen, or absorbed in some material. Out-gassing can include sublimation and evaporation (which are phase transitions of a substance into a gas), as well as desorption, seepage from cracks or internal volumes, and gaseous products of slow chemical reactions. Boiling is generally thought of as a separate phenomenon from out-gassing since it consists of a phase transition of a liquid into a vapour of the same substance.
Outlet – It is a discharge opening which is lower than the spillway crest designed to release reservoir water through or around a dam.
Outlet gate – It is a gate which is designed to control the flow of water through a reservoir outlet in or around a dam.
Outlier – In a set of data, a value so far removed from other values in the distribution that it is probably not a bona fide measurement. There are statistical methods for classifying a data point as an outlier and removing it from a data set.
Outliers – An outlier is an observation which is very different to other observations in a set of data. Since the most common cause is recording error, it is sensible to search for outliers (by means of summary statistics and plots of the data) before conducting any detailed statistical modelling. Outliers are identified as such since they ‘appear’ to be outlying with respect to a large number of apparently similar observations or experimental units according to a specified model. In several cases, outliers can be traced to errors in data collecting, recording, or calculation, and can be corrected or appropriately discarded. However, outliers can be so without a plausible explanation. In these cases, it is normally the analyst’s omission of an important variable which differentiates the outlier from the remaining otherwise similar observations, or a mis-specification of the statistical model which fails to capture the correct underlying relationships. Outliers of this latter kind are not to be discarded from the ‘other’ data unless they can be modelled separately, and their exclusion justified. Several indicators are normally used to identify outliers. One is that an observation has a value which is more than 2.5 standard deviations from the mean. Another indicator is an observation with a value more than 1.5 times the interquartile range beyond the upper or the lower quartile. It is sometimes tempting to discard outliers, but this is imprudent unless the cause of the outlier can be identified, and the outlier is determined to be spurious. Otherwise, discarding outliers can cause one to under-estimate the true variability of the data.
Out of phase – It is the condition when the alternating current (AC) generation sources are not synchronized with the grid.
Out-of-plane loads – These are the loads which are applied to the composite structures that are perpendicular to the surface of the composite structure. These loads, uniform and non-uniform, are a combination of the applied forces due to wind, roofing materials, equipment, machinery, live loads, and other factors.
Out-of-register – It is an embossed pattern distortion because of the misalignment of the male and female embossing rolls.
Out-of-roundness – It is deviation of the circumference from a circle. This can be an ovalization, i.e. an elliptic cross-section, or a local out-of-roundness, e.g., flattening. The numerical definition of out-of-roundness and ovalization is the same.
Output – It is the result of an activity which is carried out by an organization, while the outcome is the added value that is derived from the output. Output can include results, products, or outcomes produced by the processes. In case of a computer system, output is the visual, auditory, or tactile perceptions provided by the computer after processing the provided information. Examples are text, images, sound, or video displayed on a monitor or through speaker.
Outside diameter (OD) – Outside diameter of a hollow circular pipe is the measurement of the outside edges of the pipe passing through its centre. In case of gears, the outside diameter (or the tip diameter) is the diameter of the circle produced by connecting the tooth tips.
Outside screw and yoke valve – It is a valve in which the fluid does not come in contact with the stem threads. The stem sealing element is between the valve body and the stem threads.
Outsourcing – Outsourcing is when any operation or process that could be (or would usually be) performed in-house by the organizational employees is sub-contracted to another organization for a substantial period. The outsourced tasks can be performed on-site or off-site. By outsourcing, the organization uses third parties to perform noncore activities of the organization. Contracting third parties enables the organization to focus its efforts on its core competencies. Third parties that specialize in an activity are likely to be lower cost and more effective, given their focus and scale. Through outsourcing, the organization can access the state of the art in all of its operational activities without having to master each one internally.
Out time – It is the time a prepreg is exposed to ambient temperature, namely, the total quantity of time the prepreg is out of the freezer. The primary effects of out-time are to decrease the drape and tack of the prepreg while also allowing it to absorb moisture from the air.
Oval gear totalizers – The measuring element of an oval gear totalizer consists of two oval gears. The driving liquid produces the required torque, which varies as a function of the gear position, to rotate the gears. For example, the torques on the lower gear cancel each other while the torque on the upper gear is one sided and actually causes the rotation. Around the upper gear a bounded crescent like volume exists which is pushed towards the outlet of the meter. Each rotation of the pair of oval gears transports a defined liquid volume. The number of rotations is hence an exact measure of the quantity of liquid which has flowed through the meter. The precision teeth assure a good seal between the two gears. The clearance between the oval gears and the walls of the measuring chambers is so small that the leakage flow (gap loss) is negligible.
Ovality – It consists of the variation from a true circle of the cross section of a round tube, bar, or wire.
Ovaloid – It is a surface of revolution symmetrical about the polar axis which forms the end closure for a filament wound cylinder.
Oven – It is a tool which is used to expose materials to a hot environment. Ovens contain a hollow chamber and provide a means of heating the chamber in a controlled way. They are used to accomplish a wide variety of tasks needing controlled heating. Since they are used for a variety of purposes, there are many different types of ovens. These types differ depending on their intended purpose and based upon how they generate heat.
Oven machines, coke oven battery – These machines are an integral part of any coke oven battery. These machines charge the coke ovens with the coal feedstock, push the coke from the ovens after coking, and feed it to the coke quenching process. In recent times, coke oven machines are acquiring a more prominent role in the coke making process. The increasing dimensions of coke oven chambers and the demand for the high performance have spurred the development of complex coke oven machines. Apart from the traditional handling of the coal and coke flow, coke oven machines are to meet the requirements for automation, productivity, safety, and user friendliness. Nowadays, where there can be up to 150 pushing cycles per day, so called ‘single spot operation’ of these machines, which involves no additional travelling, has become standard norm for each cycle.
Oven pressure regulation system – At any given point of time, pressure inside individual coke ovens is different since they are at different stages of coking periods. It is a known fact that coke ovens which are freshly charged witness highest pressure while coke ovens which are nearing their coking time witness lowest pressures. This has two effects namely (i) coke ovens at a higher pressure in comparison to gas collecting main are more prone to have fugitive emissions, and (ii) adjacent coke ovens operating at different pressures have different levels of stress on the oven chamber walls hence, reducing the refractory life considerably. In order to overcome these serious issues, it is important to regulate pressures in individual ovens so as to maintain a slightly negative pressure throughout the coking period. This can be easily achieved by installing oven pressure regulation system.
Oven soldering – It is a non-standard term for furnace soldering .
Over-aging – It consists of aging under conditions of time and temperature higher than those needed to get maximum change in a certain property, so that the property is altered in the direction of the initial value. Over-ageing is artificial ageing treatment at too high a temperature, or for too long a time, after the maximum hardening effect has been achieved. It causes some loss of properties. In some cases, it can be a deliberate act, e.g., to improve resistance to stress corrosion or to minimize any further loss of properties in alloys operating at higher temperatures.
Overbasing – It is a technique for increasing the basicity of lubricants. Overbased lubricants are used to assist in neutralizing acidic oxidation products.
Over-bending – It consists of bending metal through a higher arc than that needed in the finished part to compensate for spring-back.
Over-dispersion parameter – It is a parameter in the negative binomial regression model which allows for the possibility that the variance of the study end point can be larger than the mean of the study end point.
Over-draft – It is a condition wherein a metal curves upward on leaving the rolls because of the higher speed of the lower roll.
Over-fill – it is the fill of a die cavity with a quantity of powder which is in excess of the specification.
Overfiring – In porcelain enamel, it is a condition sometimes occurring during firing when the temperature of the furnace is too high or the ware is left in the furnace for a greater length of time than necessary.
Over-head costs – It is the cost which is not directly associated with the production of identifiable goods or services. In production costs there are usually two types of overhead namely works overheads and administrative overheads. Works overheads are for the fixed expenditure directly related to production departments while the administrative overheads are because of those fixed expenditure which are outside the production departments. Over-head costs is sometimes called burden or indirect costs.
Over-head drive press – It is a mechanical press with the driving mechanism mounted in or on the crown or upper parts of the uprights.
Over-head line – It consists of the power transmission or telecommunication wires which run on poles or other structures outside plant.
Over-head position – It is the position in which welding is performed from the underside of the joint.
Over-head travelling crane – An overhead travelling crane is also known as a bridge crane. It is a type of crane where the hook and the line mechanism run along a horizontal beam which itself runs along two widely separated rails normally in a long factory building and runs along rails along the two long walls of the building. The crane includes a hoist to lift the items, the bridge, which spans the area covered by the crane, and a trolley to move along the bridge. The bridge girders of the overhead travelling crane can be built using typical steel beams or a more complex box girder type. The advantage of the box girder type configuration results in a system which has a lower deadweight yet a stronger overall system integrity. The configuration of overhead travelling crane can be either under running or top running.
Overhead valve engine – It is a piston engine whose valves are located in the cylinder head above the combustion chamber. This contrasts with flat-head (or side-valve) engines, where the valves are located below the combustion chamber in the engine block.
Over-heating – It consists of heating a metal or alloy to such a high temperature that its properties are reduced. When the original properties cannot be restored by further heat treating, by mechanical working, or by a combination of working and heat treating, the overheating is known as burning. In ferrous alloys, heating to an excessively high temperature so that the properties/ structure undergo modification. The resulting structure is very coarse grained. Unlike burning, it can be possible to restore the original properties / structure by further heat treatment, mechanical working, or both. In aluminum alloys, over-heating produces structures that shows areas of resolidified eutectic or other evidence indicating the metal has been heated within the melting range.
Over-lap – In resistance seam welding, it is the area in a given weld which is remelted by the succeeding weld. It is the protrusion of the weld metal over the weld toe or weld root (because of lack of fusion). This can be caused by insufficient amperage or travel speed.
Over-lap (resistance seam welding) – It is the portion of the preceding weld nugget remelted by the succeeding weld.
Over-laying – It is a nonstandard term for surfacing.
Overlay sheet – It is a non-woven fibrous mat (of glass, synthetic fibre, and so on) which is used as the top layer in a cloth or mat lay-up to provide a smoother finish, minimize the appearance of the fibrous pattern, or permit machining or grinding to a precise dimension. It is also called surfacing mat.
Over-loading – An electrical system is said to be overloaded when the current drawn by the devices connected to the circuit exceeds the pre-fixed capacity of electricity. Overload relays protect the motor, motor branch circuit, and motor branch circuit components from excessive heat from the overload condition.
Over-mix – It is the mixing of a powder longer than necessary to produce adequate distribution of the powder particles. Over mixing can cause particle size segregation.
Over-peening effects – Over-peening is excessive peening because of which the shot peening effect on the peened surface is decreased because of the reduction in the cold work generated by the shot impacts.
Over-pickling – It consists of using pickling solutions of greater strength or at higher temperature than recommended, or allowing the work-piece to remain in the pickling tanks for a greater length of time than necessary. Over-pickling can lead to blistering of subsequently applied porcelain enamel finishes.
Over-pressure – It is the minimum operating pressure of a hot water boiler sufficient to prevent the water from steaming.
Over-sampling – It consists of sampling a signal at a rate which is higher than needed by the Nyquist criterion.
Over-shoot – It is the occurrence of a signal or function exceeding its target. It arises especially in the step response of band-limited systems such as low-pass filters. It is frequently followed by ringing, and at times conflated with the latter. In control theory, overshoot refers to an output exceeding its final, steady-state value.
Over-sinter – It is sintering of a compact at higher temperature or for longer time periods than necessary to get the desired micro-structure or physical properties. It frequently leads to swelling because of the excessive pore formation.
Over-size powder – It consists of powder particles which are larger than the maximum permitted by a particle size specification.
Over-stressing – In fatigue testing, cycling at a stress level higher than that used at the end of the test.
Overturned – It is the case, where the oldest sedimentary rock beds are lying on top of a younger beds.
Over-voltage – It is the application of more than rated voltage to a device.
Oxalic acid – It is an organic acid with the chemical formula (COOH)2 or (CO2H)2 or H2C2O4. It is the simplest dicarboxylic acid. It is a white crystalline solid that forms a colourless solution in water. It is a reducing agent and its conjugate bases hydrogen oxalate (HC2O−4) and oxalate (C2O2−4) are chelating agents for metal cations. It is used as a cleaning agent, especially for the removal of rust, since it forms a water-soluble ferric iron complex, the ferrioxalate ion. Oxalic acid typically occurs as the dihydrate with the formula H2C24·2H2O.
Oxalate coating – It is a chemical coating which is suitable to act as a lubricant carrier. It is produced on stainless steels and most types of nickel / chrome alloys with a process based on oxalates and oxalic acid. Oxalate coatings are formed on alloy steel substrates to facilitate cold working because of the lower coefficient of friction of the coating.
Oxidation – It is the chemical combination with oxygen. It is a reaction in which there is an increase in valence resulting from a loss of electrons. It is also a corrosion reaction in which the corroded metal forms an oxide which is normally applied to reaction with a gas containing elemental oxygen, such as air. High temperatures increase the rate of oxidation. Oxidation is also a chemical reaction in which one substance is changed to another by oxygen combining with the substance. Much of the dross from holding and melting furnaces is the result of oxidation of the alloy held in the furnace. In case of minerals, oxidation is a chemical reaction caused by exposure to oxygen which results in a change in the chemical composition of the mineral. In carbon / graphite fibre processing, it is the step of reacting the precursor polymer (rayon, poly-acrylo-nitrile abbreviated as PAN, or pitch) with oxygen, resulting in stabilization of the structure for the hot stretching operation.
Oxidation grain size – It means determination of grain size by holding a sample at a suitably high temperature in a mildly oxidizing atmosphere. The sample is polished before oxidation and etched afterwards. It refers to the method involving heating a polished steel sample to a specified temperature, followed by quenching and repolishing. The grain boundaries are sharply defined by the presence of iron oxide.
Oxidation losses – It is the reduction in the quantity of metal or alloy through oxidation.
Oxidation reaction – In electro-chemistry, it is a chemical reaction which occurs at an anodic site by the liberation of electrons.
Oxidation reduction – It means to change the valence state of oxide scale and rust to soluble forms for removal from metal surfaces. Rust is chemically changed in this way to a more soluble form, easily dissolved by acids.
Oxidation resistance – It is the ability of a material to resist degradation by reacting with air or another gas to form a surface oxide.
Oxidative wear – It is a corrosive wear process in which chemical reaction with oxygen or oxidizing environment predominates. It is a type of wear resulting from the sliding action between two metallic components which generate oxide films on the metal surfaces. These oxide films prevent the formation of a metallic bond between the sliding surfaces, resulting in fine wear debris and low wear rates.
Oxide discolouration – It is a discolouration because of non-uniform oxidation of the metal surface during solution heat treatment.
Oxide dispersion strengthened (ODS) alloys – These alloys consist of a class of materials in which fine oxide particles are incorporated in metal powders, compacted, and then fabricated into finished forms by deformation processing. The resulting material has improved thermal softening resistance with excellent thermal and electrical conductivity. Oxide dispersion strengthened alloys are alloys which consist of a metal matrix with small oxide particles dispersed within it. They have high heat resistance, strength, and ductility. Alloys of nickel are the most common but includes iron aluminum alloys. Applications include high temperature turbine blades and heat exchanger tubing, while steels are used in nuclear applications. Oxide dispersion strengthened materials are used on spacecraft to protect the vehicle, especially during re-entry.
Oxide film – It is a typical ultra-thin oxide film consists of a single monolayer of an oxide material on a crystalline metal support. In case of iron and steel, an oxide film refers to a layer of compounds formed on the surface of iron, consisting of inner magnetite and outer hematite or maghemite layers. These films can impact the performance of iron in reactions by hindering mass and electron transport. In case of aluminum, whenever a freshly created surface is exposed to air or water at room temperature, an oxide film is formed immediately and grows to a thickness of around 5 nanometers in air and to a somewhat higher thickness in water. The film thickness increases at high temperature. Majority of the aluminum alloys have good corrosion resistance resulting from a thin, compact, adherent oxide film that forms on the surface. Without this protective film, aluminum is a reactive metal with poor corrosion resistance.
Oxide film replica – It is a thin film of an oxide of the sample to be examined. The replica is prepared by air, oxygen, chemical, or electro-chemical oxidation of the parent metal and is subsequently freed mechanically or chemically for examination.
Oxide fuels – In nuclear power plant, it is the enriched or natural uranium in the form of oxide UO2, or mixed oxide (MOX) which is used in several types of reactors. Pure metal fuels can also be used in other reactor designs (e.g., Magnox).
Oxide layer glaze – It describes the frequently shiny, wear-protective layer of oxide formed when two metals (or a metal and ceramic) are slid against each other at high temperature in an oxygen-containing atmosphere. The layer forms on either or both of the surfaces in contact and can protect against wear.
Oxide scale – It is almost always associated with the hot working. Except for highly reactive and expensive metallic systems, where jacketing (e.g., zirconium alloys) or protective coating (e.g., glass coating) is used, the oxide scale is typically a part of any thermo mechanical process practice of warm / hot working. The oxide scale is frequently complex. For example, in hot steel, the scale consists of three layers namely (i) inner wustite (FeO), (ii) intermediate magnetite (Fe3O4), and (iii) outer hematite (Fe2O3), with interesting surface characteristics. The scale has strong implications to die-tool and metal interactions and to heat transfer. But the more important technologically is the control and removal of oxide scale. High-pressure water jets are an integral part of a modern hot rolling mill where water jets are used to control the severity of oxide scale. Even then an entire pickling process and the technology of pickling are usually associated with the thermo mechanical process technology. Improper pickling leads to surface defects (such as pickling blisters etc.) and even to embrittlement.
Oxides of nitrogen – Nitrogen oxides (NOx) are a group of gases made up of varying quantities of oxygen and nitrogen molecules. Two most important oxides of nitrogen, which are air pollutants, are nitric 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, nitrogen di-oxide is the more toxic and irritating compound. Nitric oxide is a principal by-product of combustion process, arising from the high temperature reaction between nitrogen and oxygen in the combustion air and from the oxidation of organically bound nitrogen in certain fuels such as coal and oil. While nitric oxide is the dominant NOx compound emitted by most sources, nitrogen di-oxide fraction from a source varies somewhat with the type of source. Once emitted, nitric oxide can be oxidized quite effectively to nitrogen di-oxide in the atmosphere through atmospheric reactions. Nitric oxide is colourless, odourless gas. It is nonflammable and is soluble in water. It is a toxic gas. Nitrogen di-oxide is a reddish-orange-brown gas with sharp and pungent odour. It is toxic and highly corrosive. It absorbs light over much of the visible spectrum.
Oxide stringers – Any oxides which form during welding are to be removed by abrasive blasting or grinding. If such films are not removed as they accumulate on multiple-pass welds, then they can become thick enough to inhibit weld fusion and produce unacceptable laminar-type oxide stringers along the weld axis.
Oxide-type inclusions – These are oxide compounds occurring as non-metallic inclusions in metals, normally as a result of deoxidizing additions. In wrought steel products, they can occur as a stinger formation composed of distinct granular or crystalline-appearing particles.
Oxidized steel surface – It is a surface having a thin, tightly adhering oxidized skin (from straw to blue in colour), extending in from the edge of a coil or sheet.
Oxidizing agent – It is a compound which causes oxidation, hence itself being reduced. It is a substance in a redox chemical reaction which gains or ‘accepts’ / ‘receives’ an electron from a reducing agent. In other words, an oxidizer is a substance which oxidizes another substance.
Oxidizing atmosphere – It is an atmosphere which tends to promote the oxidation of immersed materials. It is a furnace atmosphere with an oversupply of oxygen which tends to oxidize materials placed in it.
Oxidizing flame – It is a gas flame produced with excess oxygen in the inner flame which has an oxidizing effect.
Oxy-acetylene cutting – It is an oxy-fuel gas cutting process in which the fuel gas is acetylene.
Oxy-acetylene welding – It is an oxy-fuel gas welding process in which the fuel gas is acetylene.
Oxy fuel burners – Oxy-fuel burners are installed in electric arc furnaces to reduce electricity consumption by substituting electricity with oxygen and hydrocarbon fuels. This technology has been introduced for improving melting rates and to provide more even heat distribution throughout the furnace. It reduces total energy consumption because of reduced heat times, increases heat transfer during the refining period, and facilitates slag foaming, which increases efficiency of oxygen usage and injected carbon.
Oxy-fuel combustion – It is the process of burning a fuel using pure oxygen, or a mixture of oxygen and recirculated flue gas, instead of air. Since the nitrogen component of air is not heated, fuel consumption is reduced, and higher flame temperatures are possible. Historically, the primary use of oxy-fuel combustion has been in welding and cutting of metals, especially steel, since oxy-fuel allows for higher flame temperatures than can be achieved with an air-fuel flame. Oxy-fuel combustion represents an emerging novel approach to near zero-emission and cleaner fossil fuel combustion. It is accomplished by burning the fuel in pure oxygen instead of air. By eliminating nitrogen in the combustion process, the exhaust of the flue gas stream is mainly composed of water and carbon di-oxide, without any nitrogen. High purity carbon di-oxide can be recovered by condensation of water. However, when fuel is burnt in pure oxygen, the flame temperature is much higher than that in a normal air-blown burner and the conventional material of construction for the burner is not able to withstand this high temperature. Hence, either the material of construction is to be improved or the flame temperature is to be lowered. The development of high temperature resistant materials has been slow because it is a major research and development undertaking. There are a number of methods, which can be used to moderate the flame temperature, the most common being carbon di-oxide recycling. In carbon di-oxide recycling, a portion of the carbon di-oxide rich flue gas stream is recycled back to the burner to lower the flame temperature similar to that in a normal air-blown burner. Another method is to use water injection rather than carbon di-oxide recycling to control the flame temperature. This is frequently referred to as ‘hydroxy-fuel’ combustion. Effectively, these two options allow the continual use of conventional refractory material until new high temperature resistant material can be developed. A primary benefit of oxy-fuel combustion is the very high-purity carbon di-oxide stream which is produced during combustion. After trace contaminants are removed, this carbon di-oxide stream is more easily purified and removed than post-combustion capture. Because of this, oxy-fuel combustion has also received a lot of attention in recent decades as a potential carbon capture and storage technology.
Oxy-fuel detonation process – It is the other name of oxy-fuel powder spray process.
Oxy-fuel gas – It is the gas used for oxy-fuel processes. Oxy-fuel processes can use a variety of fuel gases (or combustible liquids), the most common being acetylene. Other gases which can be used are propylene, liquified petroleum gas (LPG), propane, natural gas, hydrogen, and MAPP gas which is a stabilized mixture of methyl-acetylene (propyne), propadiene and propane.
Oxy-fuel gas cutting – It is any of a group of processes which is used to sever metals by means of chemical reaction between hot base metal and a fine stream of oxygen. The necessary metal temperature is maintained by gas flames resulting from combustion of a specific fuel gas such as acetylene, hydrogen, natural gas, propane, propylene, or Mapp gas (stabilized methylacetylene-propadiene).
Oxy-fuel gas spraying – it is a non-standard term for flame spraying.
Oxy-fuel gas welding (OFW) – It is any of a group of processes which is used to fuse metals together by heating them with gas flames resulting from combustion of a specific fuel gas such as acetylene, hydrogen, natural gas, or propane. The process can be used with or without the application of pressure to the joint, and with or without adding any filler metal.
Oxy-fuel powder (OFP) spray process – It is a thermal spray process. This process extends the range of available coatings and subsequent applications to include ceramics, cermets, carbides, and fusible hard-facing coatings. Using either gravity flow or pressurized feed, powder is fed into the gun and carried to the gun nozzle, where it is melted and projected by the gas stream onto a prepared surface. For general-purpose spraying, the gravity-flow system is used. When exacting coating consistency and / or high spray rates are desired, the pressurized feed system is used. Oxy-fuel powder guns are the lowest cost thermal spray equipment and are easiest to set up and change coating materials. The oxy-fuel powder spray process finds widest use in short-run machinery maintenance work and in the production spraying of abradable clearance-control seals for gas turbine engines.
Oxy-fuel wire spray process – It is also called wire flame spraying or the combustion wire process. It is the oldest of the thermal spray coating methods and among the lowest in capital investment. The process utilizes an oxygen-fuel gas flame as a heating source and coating material in wire form. Solid rod feed stock has also been used. During operation, the wire is drawn into the flame by drive rolls which are powered by an adjustable air turbine or electric motor. The tip of the wire is melted as it enters the flame and is atomized into particles by a surrounding jet of compressed air and propelled to the work-piece.
Oxy-gas cutting – The preferred term is oxygen cutting which consists of a group of cutting processes that is used to sever or remove metals by means of the chemical reaction between oxygen and the base metal at high temperatures. In the case of oxidation-resistant metals, the reaction is facilitated by the use of a chemical flux or metal powder.
Oxygen – It is a chemical element with the symbol ‘O’ and atomic number 8. It is a highly reactive non-metal, and a potent oxidizing agent which readily forms oxides with majority of the elements as well as with other compounds. At standard temperature and pressure, two oxygen atoms bind covalently to form di-oxygen, a colourless and odourless di-atomic gas with the chemical formula O2. Di-atomic gas presently constitutes 20.95 % molar fraction of the earth’s atmosphere. Oxygen is an active component of the atmosphere making up 20.94 % by volume or 23 % by weight of the air. It is a colourless, odourless, and tasteless gas. It is highly oxidizing. Oxygen reacts vigorously with combustible materials, especially in its pure state, releasing heat in the reaction process. Several reactions need the presence of water or are accelerated by a catalyst. Oxygen has a low boiling / condensing point which is -183 deg C. The gas is around 1.11 times heavier than air and is slightly soluble in water and alcohol. Below its boiling point, oxygen is a pale blue liquid slightly heavier than water. Oxygen is produced in large quantities and at high purity as a gas or liquid by cryogenic distillation process and in smaller quantities as a lower purity gas (typically around 93 %) by adsorption technologies such as pressure swing adsorption (PSA) or vacuum pressure swing adsorption (VPSA) or vacuum swing adsorption (VSA).
Oxygen arc cutting – It consists of an oxygen cutting process which is used to sever metals by means of the chemical reaction of oxygen with the base metal at elevated temperatures. The necessary temperature is maintained by an arc between a consumable tubular electrode and the base metal.
Oxygen attack – It is the corrosion or pitting in a boiler caused by oxygen.
Oxygen blowing lance, basic oxygen furnace – In the basic oxygen furnace (BOF) steelmaking a water-cooled lance is used for injecting a high velocity (super-sonic) stream of oxygen onto the liquid bath for its refining. The velocity or momentum of the oxygen jet results in the penetration of the liquid slag and metal to promote oxidation reactions over a relatively small area. The velocity of the oxygen jet and the penetration characteristics are functions of the nozzle (lance tip) design. The top-blowing lance oxygen jet of the basic oxygen furnace converter works as the source of feeding oxygen and energy for stirring of the liquid metal in the bath.
Oxygen concentration cell – It is also known as differential aeration cell. It is an electrolytic cell , the electromotive force of which is because of a difference in air (oxygen) concentration at one electrode as compared with that at another electrode of the same material.
Oxygen corrosion – It is the degradation of metals and the reaction of dissolved ions in the presence of oxygen to form insoluble deposits due to the rapid rate of oxidation.
Oxygen cutter – It is the person who performs a manual oxygen cutting operation.
Oxygen cutting – It consists of a group of cutting processes which are used to sever or remove metals by means of the chemical reaction between oxygen and the base metal at high temperatures. In the case of oxidation-resistant metals, the reaction is facilitated by the use of a chemical flux or metal powder.
Oxygen cutting operator – It is the person who operates machine or automatic oxygen cutting equipment.
Oxygen deficiency – It is a form of crevice corrosion in which galvanic corrosion proceeds since oxygen is prevented from diffusing into the crevice.
Oxygen demanding wastes – These are the waste waters such as, domestic and municipal sewage and waste water from certain industries have considerable concentration of bio-degradable organic compounds either in suspended, colloidal or dissolved form. These wastes undergo degradation and decomposition by bacterial activity. The dissolved oxygen available in the water body gets consumed for aerobic oxidation of organic matter present in the waste water. Hence, depletion of the dissolved oxygen takes place. This adversely affects the aquatic life if the dissolved oxygen falls below critical level. The decrease of dissolved oxygen is an index of pollution.
Oxygen enrichment of air – It is a crucial process to get oxygen-rich streams for several industrial applications. In recent years, oxygen-enriched air (OEA) is seen as a promising technology to facilitate energy-efficient carbon capture. High purity oxygen-enriched air (90 % to 95 % oxygen) can be used for oxy-combustion to directly sequester or valorize the carbon di-oxide rich flue gas. Also, coupling of oxygen enrichment (50 % to 80 % oxygen) with the post-combustion capture can be an attractive hybrid capture strategy for the reduction of energy penalty. oxygen-enriched air can also be highly advantageous for economic fuel combustion as the quantity of fuel needed in combustion processes for a fixed power production can be significantly reduced with low-purity oxygen-enriched air with oxygen concentration of 25 % to 30 %. Normally, replacing air with low-purity oxygen-enriched air can reduce the volume of process gas and can increase process efficiency. For example, the use of oxygen-enriched air in the Claus process for sulphur recovery has been predicted to yield cost savings up to 40 % attributing to the increase in the combustion temperature and the sulphur processing capacity of the furnace. Hydrocarbon oxidation processes can also benefit from oxygen-enriched air, e.g., the yield of terephthalic acid from p-xylene can be increased and corresponding production cost can be decreased. oxygen-enriched air has also been proposed for increasing the capacity of catalyst regeneration in fluidized catalytic cracking.
Oxygen-free – It is referred to the absence of oxygen in an environment or in a material.
Oxygen-free copper – It is the electrolytic copper free from cuprous oxide, produced without the use of residual metallic or metalloidal deoxidizers. It is a grade of copper which is preferred for electrical applications for its low electrical resistance.
Oxygen gouging – It consists of an application of oxygen cutting in which a bevel or groove is formed.
Oxygen grooving – It is a non-standard term for oxygen gouging.
Oxygen injection lance – It is a specialized tool which is used in industrial processes to introduce controlled quantities of oxygen into high-temperature environments. It typically consists of a long tube or lance made of heat-resistant materials, with an opening or nozzle at the end for oxygen release. The lance is designed to withstand extreme temperatures and harsh conditions. The purpose of an oxygen injection lance is to improve combustion and improve the efficiency of various industrial processes. By injecting oxygen directly into the combustion zone, it increases the availability of oxygen for chemical reactions, resulting in more complete and intense combustion. This, in turn, leads to increased heat generation, improved energy efficiency, and enhanced productivity in industries such as steel production, waste incineration, and other applications where high temperatures and controlled combustion are crucial.
Oxygen lance – It is a length of pipe which is used to convey oxygen to the point of cutting in oxygen lance cutting.
Oxygen lance cutting – It is an oxygen cutting process which is used to sever metals with oxygen supplied through a consumable lance. The preheat to start the cutting is done by other means.
Oxygen lancing – It is a non-standard term for oxygen lance cutting.
Oxygen probe – It is an atmosphere-monitoring device which electronically measures the difference between the partial pressure of oxygen in a furnace or furnace supply atmosphere and the external air.
Oxygen steelmaking process – It is a generic name given to those processes in which gaseous oxygen is used as the primary agent for autothermic generation of heat as a result of the oxidation of dissolved impurities like carbon, silicon, manganese, and phosphorus, and to a limited extent the oxidation of iron itself. Several types of oxygen steelmaking processes are practiced, including top blowing, bottom blowing and combined blowing. The essential features of conventional steelmaking are the partial oxidation of the carbon, silicon, phosphorus and manganese present in the hot metal and the accompanying reduction in sulphur levels.
Oxygen top blown converter process – This process involves the charging of hot metal and steel scrap into a vessel or ‘converter’. A ‘lance’ is inserted into the top of the converter, and oxygen is blown into the liquid. The oxygen reacts with the iron to form an iron oxide, which reacts with carbon, as per the reaction FeO + C = Fe + CO.
Oxy-hydrogen welding – It is an oxy-fuel gas welding process which produces coalescence of materials by heating them with a gas flame or flames obtained from the combustion of hydrogen with oxygen, without the application of pressure and with or without the use of filler metal.
Oyane damage criterion – It is based on stress triaxiality, which implicates the initiation of fracture.
Ozone – It is an inorganic molecule with the chemical formula ‘O3’ It is a pale blue gas with a distinctively pungent smell. It is an allotrope of oxygen that is much less stable than the di-atomic allotrope oxygen (O2), breaking down in the lower atmosphere to O2 (di-oxygen). Ozone is formed from di-oxygen by the action of ultra-violet (UV) light and electrical discharges within the earth’s atmosphere. It is present in very low concentrations throughout the atmosphere, with its highest concentration high in the ozone layer of the stratosphere, which absorbs most of the Sun’s ultraviolet (UV) radiation. Ozone’s odour is reminiscent of chlorine, and detectable by several people at concentrations of as little as 0.1 parts per million (ppm) in air.
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