Dictionary of Engineering

a: Category : electricity(see ampere)
a axis: Category : mechanical engineering; The angle that specifies the rotation of a machine tool about the x axis.
A block: Category : civil engineering; A hollow concrete masonry block with one end closed and the other open and with a web between, so that when the block is laid in a wall two cells are produced.
A frame: Category : building construction engineering; A dwelling whose main frames are in the shape of the letter A.Two poles supported in an upright position by braces or guys and used for lifting equipment. Also known as double mast.
A size: Category : engineering; One of a series of sizes to which trimmed paper and board are manufactured, for size AOf a sheet of paper, the dimensions 8.5 inches by 11 inches (216 millimeters by 279 millimeters).
abandon: Category : engineering; To stop drilling and remove the drill rig from the site of a borehole before the intended depth or target is reached.
abat-jour: Category : building construction; A device that is used to deflect daylight downward as it streams through a window.
abattoir: Category : industrial engineering; A building in which cattle or other animals are slaughtered.
abat-vent: Category : building construction; A series of sloping boards or metal strips, or some similar contrivance, to break the force of wind without being an obstruction to the passage of air or sound, as in a louver or chimney cowl.
ablatograph: Category : engineering; An instrument that records ablation by measuring the distance a snow or ice surface falls during the observation period.
abnormal reading: Category : industrial engineering(see abnormal time)
abnormal time: Category : industrial engineering; During a time study, an elapsed time for any element which is excessively longer or shorter than the median of the elapsed times. Also known as abnormal reading.
abort branch: Category : control systems; A branching instruction in the program controlling a robot that causes a test to be performed on whether the tool-center point is properly positioned, and to reposition it if it drifts out of the acceptable range.
Abrams' law: Category : civil engineering; In concrete materials, for a mixture of workable consistency the strength of concrete is determined by the ratio of water to cement.
abrasion test: Category : mechanical engineering; The measurement of abrasion resistance, usually by the weighing of a material sample before and after subjecting it to a known abrasive stress throughout a known time period, or by reflectance or surface finish comparisons, or by dimensional comparisons.
abrasive belt: Category : mechanical engineering; A cloth, leather, or paper band impregnated with grit and rotated as an endless loop to abrade materials through continuous friction.
abrasive blasting: Category : mechanical engineering; The cleaning or finishing of surfaces by the use of an abrasive entrained in a blast of air.
abrasive cloth: Category : mechanical engineering; Tough cloth to whose surface an abrasive such as sand or emery has been bonded for use in grinding or polishing.
abrasive cone: Category : mechanical engineering; An abrasive sintered or shaped into a solid cone to be rotated by an arbor for abrasive machining.
abrasive disk: Category : mechanical engineering; An abrasive sintered or shaped into a disk to be rotated by an arbor for abrasive machining.
abrasive jet cleaning: Category : engineering; The removal of dirt from a solid by a gas or liquid jet carrying abrasives to ablate the surface.
abrasive machining: Category : mechanical engineering; Grinding, drilling, shaping, or polishing by abrasion.
abreast milling: Category : mechanical engineering; A milling method in which parts are placed in a row parallel to the axis of the cutting tool and are milled simultaneously.
abreuvoir: Category : civil engineering; A space between stones in masonry to be filled with mortar.
ABS: Category : mechanical engineering(see antilock braking system)
absolute altimeter: Category : engineering; An instrument which employs radio, sonic, or capacitive technology to produce on its indicator the measurement of distance from the aircraft to the terrain below. Also known as terrain-clearance indicator.
absolute altitude: Category : engineering; Altitude above the actual surface, either land or water, of a planet or natural satellite.
absolute block system: Category : civil engineering; A block system in which only a single railroad train is permitted within a block section during a given period of time.
absolute blocking: Category : civil engineering; A control arrangement for rail traffic in which a track is divided into sections or blocks upon which a train may not enter until the preceding train has left.
absolute efficiency: Category : engineering acoustics; The ratio of the power output of an electroacoustic transducer, under specified conditions, to the power output of an ideal electroacoustic transducer.
absolute expansion: Category : thermodynamics; The true expansion of a liquid with temperature, as calculated when the expansion of the container in which the volume of the liquid is measured is taken into account, in contrast with apparent expansion.
absolute instrument: Category : engineering; An instrument which measures a quantity (such as pressure or temperature) in absolute units by means of simple physical measurements on the instrument.
absolute magnetometer: Category : engineering; An instrument used to measure the intensity of a magnetic field without reference to other magnetic instruments.
absolute pressure gage: Category : engineering; A device that measures the pressure exerted by a fluid relative to a perfect vacuum, used to measure pressures very close to a perfect vacuum.
absolute pressure transducer: Category : engineering; A device that responds to absolute pressure as the input and provides a measurable output of a nature different than but proportional to absolute pressure.
absolute scale: Category : thermodynamics(see absolute temperature scale)
absolute specific gravity: Category : mechanics; The ratio of the weight of a given volume of a substance in a vacuum at a given temperature to the weight of an equal volume of water in a vacuum at a given temperature.
absolute stop: Category : civil engineering; A railway signal which indicates that the train must make a full stop and not proceed until there is a change in the signal. Also known as stop and stay.
absolute temperature scale: Category : thermodynamics; A scale with which temperatures are measured relative to absolute zero. Also known as absolute scale.
absolute volume: Category : engineering; The total volume of the particles in a granular material, including both permeable and impermeable voids but excluding spaces between particles.
absolute weighing: Category : engineering; Determination of the mass of a sample and expressing its value in units, fractions, and multiples of the mass of the prototype of the international kilogram.
absolute zero: Category : thermodynamics; The temperature of -273.16°C, or -459.69°F, or 0 K, thought to be the temperature at which molecular motion vanishes and a body would have no heat energy.
absorber capacity: Category : chemical engineering; During natural gas processing, the maximum volume of the gas that can be processed through an absorber without alteration of specified operating conditions.
absorber plate: Category : engineering; A part of a flat-plate solar collector that provides a surface for absorbing incident solar radiation.
absorbing boom: Category : civil engineering; A device that floats on the water and is used to stop the spread of an oil spill and aid in its removal.
absorbing well: Category : civil engineering; A shaft that permits water to drain through an impermeable stratum to a permeable stratum.
absorption bed: Category : civil engineering; A sizable pit containing coarse aggregate about a distribution pipe system, absorbs the effluent of a septic tank.
absorption column: Category : engineering(see absorption tower)
absorption cycle: Category : mechanical engineering; In refrigeration, the process whereby a circulating refrigerant, for example, ammonia, is evaporated by heat from an aqueous solution at elevated pressure and subsequently reabsorbed at low pressure, displacing the need for a compressor.
absorption dynamometer: Category : engineering; A device for measuring mechanical forces or power in which the mechanical energy input is absorbed by friction or electrical resistance.
absorption field: Category : civil engineering; Trenches containing coarse aggregate about distribution pipes permitting septic-tank effluent to seep into surrounding soil. Also known as disposal field.
absorption hygrometer: Category : engineering; An instrument with which the water vapor content of the atmosphere is measured by means of the absorption of vapor by a hygroscopic chemical.
absorption loss: Category : civil engineering; The quantity of water that is lost during the initial filling of a reservoir because of absorption by soil and rocks.
absorption meter: Category : engineering; An instrument designed to measure the amount of light transmitted through a transparent substance, using a photocell or other light detector.
absorption number: Category : engineering; A dimensionless group used in the field of gas absorption in a wetted-wall column, represents the liquid side mass-transfer coefficient.
absorption plant: Category : chemical engineering; A facility to recover the condensable portion of natural or refinery gas.
absorption process: Category : chemical engineering; A method in which light oil is introduced into an absorption tower so that it absorbs the gasoline in the rising wet gas, the light oil is then distilled to separate the gasoline.
absorption refrigeration: Category : mechanical engineering; Refrigeration in which cooling is effected by the expansion of liquid ammonia into gas and absorption of the gas by water, the ammonia is reused after the water evaporates.
absorption system: Category : mechanical engineering; A refrigeration system in which the refrigerant gas in the evaporator is taken up by an absorber and is then, with the application of heat, released in a generator.
absorption tower: Category : engineering; A vertical tube in which a rising gas is partially absorbed by a liquid in the form of falling droplets. Also known as absorption column.
absorption trench: Category : civil engineering; A trench containing coarse aggregate about a distribution tile pipe through which septic-tank effluent may move beneath earth.
absorption-emission pyrometer: Category : engineering; A thermometer for determining gas temperature from measurement of the radiation emitted by a calibrated reference source before and after this radiation has passed through and been partially absorbed by the gas.
absorptivity: Category : thermodynamics; The ratio of the radiation absorbed by a surface to the total radiation incident on the surface.
Abt track: Category : civil engineering; One of the cogged rails used for railroad tracking in mountains and so arranged that the cogs are not opposite one another on any pair of rails.
abutment: Category : civil engineering; A surface or mass provided to withstand thrust, for example, end supports of an arch or a bridge.
abutting joint: Category : design engineering; A joint which connects two pieces of wood in such a way that the direction of the grain in one piece is angled (usually at 90°) with respect to the grain in the other.
abutting tenons: Category : design engineering; Two tenons inserted into a common mortise from opposite sides so that they contact.
ac: Category : electricity(see alternating current)
accelerated aging: Category : engineering; Hastening the deterioration of a product by a laboratory procedure in order to determine long-range storage and use characteristics.
accelerated life test: Category : engineering; Operation of a device, circuit, or system above maximum ratings to produce premature failure, used to estimate normal operating life.
accelerated weathering: Category : engineering; A laboratory test used to determine, in a short period of time, the resistance of a paint film or other exposed surface to weathering.
accelerating incentive: Category : industrial engineering(see differential piece-rate system)
acceleration: Category : mechanics; The rate of change of velocity with respect to time.
acceleration analysis: Category : mechanical engineering; A mathematical technique, often done graphically, by which accelerations of parts of a mechanism are determined.
acceleration measurement: Category : mechanics; The technique of determining the magnitude and direction of acceleration, including translational and angular acceleration.
acceleration of free fall: Category : mechanics(see acceleration of gravity)
acceleration of gravity: Category : mechanics; The acceleration imparted to bodies by the attractive force of the earth, has an international standard value of 980.665 cm/s² but varies with latitude and elevation. Also known as acceleration of free fall, apparent gravity.
acceleration signature: Category : industrial engineering; A printed record that shows the pattern of acceleration and deceleration of an anatomical reference point in the performance of a task.
acceleration tolerance: Category : engineering; The degree to which personnel or equipment withstands acceleration.
acceleration-error constant: Category : control systems; The ratio of the acceleration of a controlled variable of a servomechanism to the actuating error when the actuating error is constant.
accelerator: Category : mechanical engineering; A device for varying the speed of an automotive vehicle by varying the supply of fuel.
accelerator jet: Category : mechanical engineering; The jet through which the fuel is injected into the incoming air in the carburetor of an automotive vehicle with rapid demand for increased power output.
accelerator linkage: Category : mechanical engineering; The linkage connecting the accelerator pedal of an automotive vehicle to the carburetor throttle valve or fuel injection control.
accelerator pedal: Category : mechanical engineering; A pedal that operates the carburetor throttle valve or fuel injection control of an automotive vehicle.
accelerator pump: Category : mechanical engineering; A small cylinder and piston controlled by the throttle of an automotive vehicle so as to provide an enriched air-fuel mixture during acceleration.
accelerogram: Category : engineering; A record made by an accelerograph.
accelerograph: Category : engineering; An accelerometer having provisions for recording the acceleration of a point on the earth during an earthquake or for recording any other type of acceleration.
accelerometer: Category : engineering; An instrument which measures acceleration or gravitational force capable of imparting acceleration.
accelerometry: Category : industrial engineering; The quantitative determination of acceleration and deceleration in the entire human body or a part of the body in the performance of a task.
accent lighting: Category : civil engineering; Directional lighting which highlights an object or attracts attention to a particular area.
acceptability: Category : engineering; State or condition of meeting minimum standards for use, as applied to methods, equipment, or consumable products.
acceptable quality level: Category : industrial engineering; The maximum percentage of defects that has been determined tolerable as a process average for a sampling plan during inspection or test of a product with respect to economic and functional requirements of the item. Abbreviated AQL.
acceptable reliability level: Category : industrial engineering; The required level of reliability for a part, system, device, and so forth, may be expressed in a variety of terms, for example, number of failures allowable in 1000 hours of operating life. Abbreviated ARL.
acceptance criteria: Category : industrial engineering; Standards of judging the acceptability of manufactured items.
acceptance number: Category : industrial engineering; The maximum allowable number of defective pieces in a sample of specified size.
acceptance sampling: Category : industrial engineering; Taking a sample from a batch of material to inspect for determining whether the entire lot will be accepted or rejected.
acceptance test: Category : industrial engineering; A test used to determine conformance of a product to design specifications, as a basis for its acceptance.
acceptor: Category : chemical engineering; A calcined carbonate used to absorb the carbon dioxide evolved during a coal gasification process.
access: Category : civil engineering; Freedom, ability, or the legal right to pass without obstruction from a given point on earth to some other objective, such as the sea or a public highway.
access door: Category : building construction; A provision for access to concealed plumbing or other equipment without disturbing the wall or fixtures.
access flooring: Category : civil engineering(see raised flooring)
access hole: Category : engineering(see manhole)
access road: Category : civil engineering; A route, usually paved, that enables vehicles to reach a designated facility expeditiously.
access tunnel: Category : civil engineering; A tunnel provided for an access road.
accessory: Category : mechanical engineering; A part, subassembly, or assembly that contributes to the effectiveness of a piece of equipment without changing its basic function, may be used for testing, adjusting, calibrating, recording, or other purposes.
accident frequency rate: Category : industrial engineering; The number of all disabling injuries per million worker-hours of exposure.
accident severity rate: Category : industrial engineering; The number of worker-days lost as a result of disabling injuries per thousand worker-hours of exposure.
accident-cause code: Category : industrial engineering; Sponsored by the American Standards Association, the code that classifies accidents under eight defective working conditions and nine improper working practices.
accommodation: Category : control systems; Any alteration in a robot's motion in response to the robot's environment, it may be active or passive.
accordion door: Category : building construction; A door that folds and unfolds like an accordion when it is opened and closed.
accordion partition: Category : building construction; A movable, fabric-faced partition which is fitted into an overhead track and folds like an accordion.
accordion roller conveyor: Category : mechanical engineering; A conveyor with a flexible latticed frame which permits variation in length.
accretion: Category : civil engineering; Artificial buildup of land due to the construction of a groin, breakwater, dam, or beach fill.
accumulated discrepancy: Category : engineering; The sum of the separate discrepancies which occur in the various steps of making a survey.
accumulative timing: Category : industrial engineering; A time-study method that allows direct reading of the time for each element of an operation by the use of two stopwatches which operate alternately.
accustomization: Category : engineering; The process of learning the techniques of living with a minimum of discomfort in an extreme or new environment.
acetate process: Category : chemical engineering; Acetylation of cellulose (wood pulp or cotton linters) with acetic acid or acetic anhydride and sulfuric acid catalyst to make cellulose acetate resin or fiber.
acetone-benzol process: Category : chemical engineering; A dewaxing process in petroleum refining, with acetone and benzol used as solvents.
acetylene cutting: Category : engineering(see oxyacetylene cutting)
acetylene generator: Category : engineering; A steel cylinder or tank that provides for controlled mixing of calcium carbide and water to generate acetylene.
acetylene torch: Category : engineering(see oxyacetylene torch)
acfm: Category : chemical engineering(see actual cubic feet per minute)
acid blowcase: Category : chemical engineering(see blowcase)
acid cleaning: Category : engineering; The use of circulating acid to remove dirt, scale, or other foreign matter from the interior of a pipe.
acid conductor: Category : chemical engineering; A vessel designed for refortification of hydrolyzed acid by heating and evaporation of water, or sometimes by distillation of water under partial vacuum.
acid egg: Category : chemical engineering(see blowcase)
acid gases: Category : chemical engineering; The hydrogen sulfide and carbon dioxide found in natural and refinery gases which, when combined with moisture, form corrosive acids, known as sour gases when hydrogen sulfide and mercaptans are present.
acid lining: Category : engineering; In steel production, a silica-brick lining used in furnaces.
acid number: Category : engineering; A number derived from a standard test indicating the acid or base composition of lubricating oils, it in no way indicates the corrosive attack of the used oil in service. Also known as corrosion number.
acid polishing: Category : engineering; The use of acids to polish a glass surface.
acid process: Category : chemical engineering; In paper manufacture, a pulp digestion process that uses an acidic reagent, for example, a bisulfite solution containing free sulfur dioxide.
acid recovery plant: Category : chemical engineering; In some refineries, a facility for separating sludge acid into acid oil, tar, and weak sulfuric acid, with provision for later reconcentration.
acid sludge: Category : chemical engineering; The residue left after treating petroleum oil with sulfuric acid for the removal of impurities.
acid soot: Category : engineering; Carbon particles that have absorbed acid fumes as a by-product of combustion, hydrochloric acid absorbed on carbon particulates is frequently the cause of metal corrosion in incineration.
acid treatment: Category : chemical engineering; A refining process in which unfinished petroleum products, such as gasoline, kerosine, and diesel oil, are contacted with sulfuric acid to improve their color, odor, and other properties.
aciding: Category : engineering; A light etching of a building surface of cast stone.
acid-water pollution: Category : engineering; Industrial wastewaters that are acidic, usually appears in effluent from the manufacture of chemicals, batteries, artificial and natural fiber, fermentation processes (beer), and mining.
Ackerman linkage: Category : mechanical engineering(see Ackerman steering gear)
acme screw thread: Category : design engineering; A standard thread having a profile angle of 29º and a flat crest, used on power screws in such devices as automobile jacks, presses, and lead screws on lathes. Also known as acme thread.
acme thread: Category : design engineering(see acme screw thread)
acoubuoy: Category : engineering; An acoustic listening device similar to a sonobuoy, used on land to form an electronic fence that will pick up sounds of enemy movements and transmit them to orbiting aircraft or land stations.
acoustic array: Category : engineering acoustics; A sound-transmitting or sound-receiving system whose elements are arranged to give desired directional characteristics.
acoustic center: Category : engineering acoustics; The center of the spherical sound waves radiating outward from an acoustic transducer.
acoustic clarifier: Category : engineering acoustics; System of cones loosely attached to the baffle of a loudspeaker and designed to vibrate and absorb energy during sudden loud sounds to suppress these sounds.
acoustic coupler: Category : engineering acoustics; A device used between the modem of a computer terminal and a standard telephone line to permit transmission of digital data in either direction without making direct connections.
acoustic delay: Category : engineering acoustics; A delay which is deliberately introduced in sound reproduction by having the sound travel a certain distance along a pipe before conversion into electric signals.
acoustic detection: Category : engineering; Determination of the profile of a geologic formation, an ocean layer, or some object in the ocean by measuring the reflection of sound waves off the object.
acoustic fatigue: Category : mechanics; The tendency of a material, such as a metal, to lose strength after acoustic stress.
acoustic feedback: Category : engineering acoustics; The reverberation of sound waves from a loudspeaker to a preceding part of an audio system, such as to the microphone, in such a manner as to reinforce, and distort, the original input. Also known as acoustic regeneration.
acoustic generator: Category : engineering acoustics; A transducer which converts electrical, mechanical, or other forms of energy into sound.
acoustic heat engine: Category : engineering; A device that transforms heat energy first into sound energy and then into electrical power, without the use of moving mechanical parts.
acoustic hologram: Category : engineering; The phase interference pattern, formed by acoustic beams, that is used in acoustical holography, when light is made to interact with this pattern, it forms an image of an object placed in one of the beams.
acoustic horn: Category : building construction(see horn)
acoustic jamming: Category : engineering acoustics; The deliberate radiation or reradiation of mechanical or electroacoustic signals with the objectives of obliterating or obscuring signals which the enemy is attempting to receive and of deterring enemy weapons systems.
acoustic labyrinth: Category : engineering acoustics; Special baffle arrangement used with a loudspeaker to prevent cavity resonance and to reinforce bass response.
acoustic line: Category : engineering acoustics; The acoustic equivalent of an electrical transmission line, involving baffles, labyrinths, or resonators placed at the rear of a loudspeaker and arranged to help reproduce the very low audio frequencies.
acoustic ocean-current meter: Category : engineering; An instrument that measures current flow in rivers and oceans by transmitting acoustic pulses in opposite directions parallel to the flow and measuring the difference in pulse travel times between transmitter-receiver pairs.
acoustic position reference system: Category : engineering; An acoustic system used in offshore oil drilling to provide continuous information on ship position with respect to an ocean-floor acoustic beacon transmitting an ultrasonic signal to three hydrophones on the bottom of the drilling ship.
acoustic radar: Category : engineering; Use of sound waves with radar techniques for remote probing of the lower atmosphere, up to heights of about 5000 feet (1500 meters), for measuring wind speed and direction, humidity, temperature inversions, and turbulence.
acoustic radiator: Category : engineering acoustics; A vibrating surface that produces sound waves, such as a loudspeaker cone or a headphone diaphragm.
acoustic radiometer: Category : engineering; An instrument for measuring sound intensity by determining the unidirectional steady-state pressure caused by the reflection or absorption of a sound wave at a boundary.
acoustic ratio: Category : engineering acoustics; The ratio of the intensity of sound radiated directly from a source to the intensity of sound reverberating from the walls of an enclosure, at a given point in the enclosure.
acoustic reflex enclosure: Category : engineering acoustics; A loudspeaker cabinet designed with a port to allow a low-frequency contribution from the rear of the speaker cone to be radiated forward.
acoustic regeneration: Category : engineering acoustics(see acoustic feedback)
acoustic seal: Category : engineering acoustics; A joint between two parts to provide acoustical coupling with low losses of energy, such as between an earphone and the human ear.
acoustic signature: Category : engineering; In acoustic detection, the profile characteristic of a particular object or class of objects, such as a school of fish or a specific ocean-bottom formation.
acoustic spectrograph: Category : engineering; A spectrograph used with sound waves of various frequencies to study the transmission and reflection properties of ocean thermal layers and marine life.
acoustic spectrometer: Category : engineering acoustics; An instrument that measures the intensities of the various frequency components of a complex sound wave. Also known as audio spectrometer.
acoustic strain gage: Category : engineering; An instrument used for measuring structural strains, consists of a length of fine wire mounted so its tension varies with strain, the wire is plucked with an electromagnetic device, and the resulting frequency of vibration is measured to determine the amo
acoustic theodolite: Category : engineering; An instrument that uses sound waves to provide a continuous vertical profile of ocean currents at a specific location.
acoustic transducer: Category : engineering acoustics; A device that converts acoustic energy to electrical or mechanical energy, such as a microphone or phonograph pickup.
acoustic transformer: Category : engineering acoustics; A device, such as a horn or megaphone, for increasing the efficiency of sound radiation.
acoustic treatment: Category : building construction; The use of sound-absorbing materials to give a room a desired degree of freedom from echo and reverberation.
acoustic well logging: Category : engineering; A ground exploration method that uses a high-energy sound source and a receiver, both underground.
acoustical ceiling: Category : building construction; A ceiling covered with or built of material with special acoustical properties.
acoustical ceiling system: Category : building construction; A system for the structural support of an acoustical ceiling, lighting and air diffusers may be included as part of the system.
acoustical door: Category : building construction; A solid door with gasketing along the top and sides, and usually an automatic door bottom, designed to reduce noise transmission.
acoustical model: Category : civil engineering; A model used to investigate certain acoustical properties of an auditorium or room such as sound pressure distribution, sound-ray paths, and focusing effects.
acoustical treatment: Category : civil engineering; That part of building planning that is designed to provide a proper acoustical environment, includes the use of acoustical material.
acoustic-wave-based sensor: Category : engineering; A device that employs a surface acoustic wave, a thickness-shear-mode resonance (a resonant oscillation of a thin plate of material), or other type of acoustic wave to measure the physical properties of a thin film or liquid layer or, in combination with
acoustoelectronics: Category : engineering acoustics; The branch of electronics that involves use of acoustic waves at microwave frequencies (above 500 megahertz), traveling on or in piezoelectric or other solid substrates. Also known as pretersonics.
acquisition: Category : engineering; The process of pointing an antenna or a telescope so that it is properly oriented to allow gathering of tracking or telemetry data from a satellite or space probe.
acquisition and tracking radar: Category : engineering; A radar set capable of locking onto a received signal and tracking the object emitting the signal, the radar may be airborne or on the ground.
acre: Category : mechanics; A unit of area, equal to 43,560 square feet, or to 4046.8564224 square meters.
acrometer: Category : engineering; An instrument to measure the density of oils.
actinogram: Category : engineering; The record of heat from a source, such as the sun, as detected by a recording actinometer.
actinograph: Category : engineering; A recording actinometer.
actinometer: Category : engineering; Any instrument used to measure the intensity of radiant energy, particularly that of the sun.
action: Category : mechanics; An integral associated with the trajectory of a system in configuration space, equal to the sum of the integrals of the generalized momenta of the system over their canonically conjugate coordinates. Also known as phase integral.
activated sludge: Category : civil engineering; A semiliquid mass removed from the liquid flow of sewage and subjected to aeration and aerobic microbial action, the end product is dark to golden brown, partially decomposed, granular, and flocculent, and has an earthy odor when fresh.
activated-sludge effluent: Category : civil engineering; The liquid from the activated-sludge treatment that is further processed by chlorination or by oxidation.
activated-sludge process: Category : civil engineering; A sewage treatment process in which the sludge in the secondary stage is put into aeration tanks to facilitate aerobic decomposition by microorganisms, the sludge and supernatant liquor are separated in a settling tank, the supernatant liquor or effluent
active accommodation: Category : control systems; The alteration of preprogrammed robotic motions by the integrated effects of sensors, controllers, and the robotic motion itself.
active detection system: Category : engineering; A guidance system which emits energy as a means of detection, for example, sonar and radar.
active earth pressure: Category : civil engineering; The horizontal pressure that an earth mass exerts on a wall.
active illumination: Category : engineering; Lighting whose direction, intensity, and pattern are controlled by commands or signals.
active infrared detection system: Category : engineering; An infrared detection system in which a beam of infrared rays is transmitted toward possible targets, and rays reflected from a target are detected.
active leaf: Category : building construction; In a door with two leaves, the leaf which carries the latching or locking mechanism. Also known as active door.
active sludge: Category : civil engineering; A sludge rich in destructive bacteria used to break down raw sewage.
active solar system: Category : mechanical engineering; A solar heating or cooling system that operates by mechanical means, such as motors, pumps, or valves.
active sonar: Category : engineering; A system consisting of one or more transducers to send and receive sound, equipment for the generation and detection of the electrical impulses to and from the transducer, and a display or recorder system for the observation of the received signals.
active system: Category : engineering; In radio and radar, a system that requires transmitting equipment, such as a beacon or transponder.
active vibration suppression: Category : mechanical engineering; The prevention of undesirable vibration by techniques involving feedback control of the vibratory motion, whereby the forces designed to reduce the vibration depend on the system displacements and velocities.
active-cord mechanism: Category : mechanical engineering; A slender, chainlike grouping of joints and links that makes active and flexible winding motions under the control of actuators attached along its body.
activity: Category : systems engineering; The representation in a PERT or critical-path-method network of a task that takes up both time and resources and whose performance is necessary for the system to move from one event to the next.
activity chart: Category : industrial engineering; A tabular presentation of a series of operations of a process plotted against a time scale.
activity duration: Category : systems engineering; In critical-path-method terminology, the estimated amount of time required to complete an activity.
activity sampling: Category : industrial engineering(see work sampling)
actual cost: Category : industrial engineering; Cost determined by an allocation of cost factors recorded during production.
actual cubic feet per minute: Category : chemical engineering; A measure of the volume of gas at operating temperature and pressure, as distinct from volume of gas at standard temperature and pressure. Abbreviated acfm.
actual horsepower: Category : mechanical engineering(see actual power)
actual power: Category : mechanical engineering; The power delivered at the output shaft of a source of power. Also known as actual horsepower.
actual relative movement: Category : civil engineering(see slip)
actual time: Category : industrial engineering; Time taken by a worker to perform a given task.
actuate: Category : mechanical engineering; To put into motion or mechanical action, as by an actuator.
actuated roller switch: Category : mechanical engineering; A centrifugal sequence-control switch that is placed in contact with a belt conveyor, immediately preceding the conveyor which it controls.
actuating system: Category : control systems; An electric, hydraulic, or other system that supplies and transmits energy for the operation of other mechanisms or systems.
ada mud: Category : engineering; A conditioning material added to drilling mud to obtain satisfactory cores and samples of formations.
adamantine drill: Category : mechanical engineering; A core drill with hardened steel shot pellets that revolve under the rim of the rotating tube, employed in rotary drilling in very hard ground.
Adam's catalyst: Category : chemical engineering; Finely divided plantinum(IV) oxide, made by fusing hexachloroplatinic(IV) acid with NaNO₃.
adapter: Category : engineering; A device used to make electrical or mechanical connections between items not originally intended for use together.
adaptive branch: Category : control systems; A branch instruction in the computer program controlling a robot that may lead the robot to execute a series of instructions, depending on external conditions.
adaptive control: Category : control systems; A control method in which one or more parameters are sensed and used to vary the feedback control signals in order to satisfy the performance criteria.
adaptive robot: Category : control systems; A robot that can alter its responses according to changes in the environment.
adaptive structure: Category : engineering; A structure whose geometric and inherent structural characteristics can be changed beneficially in response to external stimulation by either remote commands or automatic means.
adaptive system: Category : systems engineering; A system that can change itself in response to changes in its environment in such a way that its performance improves through a continuing interaction with its surroundings.
adaptive-control function: Category : control systems; That level in the functional decomposition of a large-scale control system which updates parameters of the optimizing control function to achieve a best fit to current plant behavior, and updates parameters of the direct control function to achieve good d
adaptometer: Category : engineering; An instrument that measures the lowest brightness of an extended area that can barely be detected by the eye.
addendum: Category : design engineering; The radial distance between two concentric circles on a gear, one being that whose radius extends to the top of a gear tooth (addendum circle) and the other being that which will roll without slipping on a circle on a mating gear (pitch line).
addendum circle: Category : design engineering; The circle on a gear passing through the tops of the teeth.
adding tape: Category : engineering; A surveyor's tape that is calibrated from 0 to 100 by full feet (or meters) in one direction, and has 1 additional foot (or meter) beyond the zero end which is subdivided in tenths or hundredths.
additive synthesis: Category : engineering acoustics; A method of synthesizing complex tones by adding together an appropriate number of simple sine waves at harmonically related frequencies.
adhesional work: Category : thermodynamics; The work required to separate a unit area of a surface at which two substances are in contact. Also known as work of adhesion.
adhesive bond: Category : mechanics; The forces such as dipole bonds which attract adhesives and base materials to each other.
adhesive bonding: Category : engineering; The fastening together of two or more solids by the use of glue, cement, or other adhesive.
adhesive strength: Category : engineering; The strength of an adhesive bond, usually measured as a force required to separate two objects of standard bonded area, by either shear or tensile stress.
adiabatic: Category : thermodynamics; Referring to any change in which there is no gain or loss of heat.
adiabatic compression: Category : thermodynamics; A reduction in volume of a substance without heat flow, in or out.
adiabatic cooling: Category : thermodynamics; A process in which the temperature of a system is reduced without any heat being exchanged between the system and its surroundings.
adiabatic curing: Category : engineering; The curing of concrete or mortar under conditions in which there is no loss or gain of heat.
adiabatic engine: Category : mechanical engineering; A heat engine or thermodynamic system in which there is no gain or loss of heat.
adiabatic envelope: Category : thermodynamics; A surface enclosing a thermodynamic system in an equilibrium which can be disturbed only by long-range forces or by motion of part of the envelope, intuitively, this means that no heat can flow through the surface.
adiabatic expansion: Category : thermodynamics; Increase in volume without heat flow, in or out.
adiabatic extrusion: Category : engineering; Forming plastic objects by energy produced by driving the plastic mass through an extruder without heat flow.
adiabatic process: Category : thermodynamics; Any thermodynamic procedure which takes place in a system without the exchange of heat with the surroundings.
adiabatic vaporization: Category : thermodynamics; Vaporization of a liquid with virtually no heat exchange between it and its surroundings.
adit: Category : civil engineering; An access tunnel used for excavation of the main tunnel.
adjustable base anchor: Category : building construction; An item which holds a doorframe above a finished floor.
adjustable parallels: Category : engineering; Wedge-shaped iron bars placed with the thin end of one on the thick end of the other, so that the top face of the upper and the bottom face of the lower remain parallel, but the distance between the two faces is adjustable, the bars can be locked in posit
adjustable square: Category : engineering; A try square with an arm that is at right angles to the ruler, the position of the arm can be changed to form an L or a T. Also known as double square.
adjustable wrench: Category : engineering; A wrench with one jaw which is fixed and another which is adjustable, the size is adjusted by a knurled screw.
adjusting: Category : engineering; In measurement technology, setting or compensating a measuring instrument or a weight in such a way that the indicated value deviates as little as possible from the actual value.
adjutage: Category : engineering; A tube attached to a container of liquid at an orifice to facilitate or regulate outflow.
admittance: Category : electricity; A measure of how readily alternating current will flow in a circuit, the reciprocal of impedance, it is expressed in siemens.
adobe construction: Category : building construction; Wall construction with sun-dried blocks of adobe soil.
ADP: Category : engineering(see automatic data processing)
ADR studio: Category : engineering acoustics; A sound-recording studio used in motion-picture and television production to allow an actor who did not intelligibly record his or her speech during the original filming or video recording to do so by watching himself or herself on the screen and repeatin
adsorption system: Category : mechanical engineering; A device that dehumidifies air by bringing it into contact with a solid adsorbing substance.
advance signal: Category : civil engineering; A signal in a block system up to which a train may proceed within a block that is not completely cleared.
advance slope grouting: Category : engineering; A grouting technique in which the front of the mass of grout is forced to move horizontally through preplaced aggregate.
advance slope method: Category : engineering; A method of concrete placement in which the face of the fresh concrete, which is not vertical, moves forward as the concrete is placed.
advanced programmatic risk analysis: Category : industrial engineering; A method for managing engineering programs with multiple projects and strict resource constraints which balances both technical and management risks.
advanced sewage treatment: Category : civil engineering(see tertiary sewage treatment)
adz: Category : design engineering; A cutting tool with a thin arched blade, sharpened on the concave side, at right angles on the handle, used for rough dressing of timber.
adz block: Category : mechanical engineering; The part of a machine for wood planing that carries the cutters.
aerated flow: Category : engineering; Flowing liquid in which gas is dispersed as fine bubbles throughout the liquid.
aeration tank: Category : engineering; A fluid-holding tank with provisions to aerate its contents by bubbling air or another gas through the liquid or by spraying the liquid into the air.
aerial cableway: Category : mechanical engineering(see aerial tramway)
aerial photogrammetry: Category : engineering; Use of aerial photographs to make accurate measurements in surveying and mapmaking.
aerial photographic reconnaissance: Category : engineering(see aerial photoreconnaissance)
aerial photography: Category : engineering; The making of photographs of the ground surface from an aircraft, spacecraft, or rocket. Also known as aerophotography.
aerial photoreconnaissance: Category : engineering; The obtaining of information by air photography, the three types are strategic, tactical, and survey-cartographic photoreconnaissance. Also known as aerial photographic reconnaissance.
aerial reconnaissance: Category : engineering; The collection of information by visual, electronic, or photographic means while aloft.
aerial ropeway: Category : mechanical engineering(see aerial tramway)
aerial spud: Category : mechanical engineering; A cable for moving and anchoring a dredge.
aerial survey: Category : engineering; A survey utilizing photographic, electronic, or other data obtained from an airborne station. Also known as aerosurvey, air survey.
aerial tramway: Category : mechanical engineering; A system for transporting bulk materials that consists of one or more cables supported by steel towers and is capable of carrying a traveling carriage from which loaded buckets can be lowered or raised. Also known as aerial cableway, aerial ropeway.
aeroballistics: Category : mechanics; The study of the interaction of projectiles or high-speed vehicles with the atmosphere.
aerobic digestion: Category : chemical engineering; Digestion of matter suspended or dissolved in waste by microorganisms under favorable conditions of oxygenation.
aerobic lagoon: Category : civil engineering; An aerated pond in which sewage solids are placed, and are decomposed by aerobic bacteria. Also known as aerobic pond.
aerobic pond: Category : civil engineering(see aerobic lagoon)
aerobic-anaerobic interface: Category : civil engineering; That point in bacterial action in the body of a sewage sludge or compost heap where both aerobic and anaerobic microorganisms participate, and the decomposition of the material goes no further.
aerobic-anaerobic lagoon: Category : civil engineering; A pond in which the solids from a sewage plant are placed in the lower layer, the solids are partially decomposed by anaerobic bacteria, while air or oxygen is bubbled through the upper layer to create an aerobic condition.
aerochlorination: Category : civil engineering; Treatment of sewage with compressed air and chlorine gas to remove fatty substances.
aerodrome: Category : civil engineering(see airport)
aerodynamic balance: Category : engineering; A balance used for the measurement of the forces exerted on the surfaces of instruments exposed to flowing air, frequently used in tests made on models in wind tunnels.
aerodynamic trajectory: Category : mechanics; A trajectory or part of a trajectory in which the missile or vehicle encounters sufficient air resistance to stabilize its flight or to modify its course significantly.
aeroelasticity: Category : mechanics; The deformation of structurally elastic bodies in response to aerodynamic loads.
aerofall mill: Category : mechanical engineering; A grinding mill of large diameter with either lumps of ore, pebbles, or steel balls as crushing bodies, the dry load is airswept to remove mesh material.
aerofilter: Category : civil engineering; A filter bed for sewage treatment consisting of coarse material and operated at high speed, often with recirculation.
aerograph: Category : engineering; Any self-recording instrument carried aloft by any means to obtain meteorological data.
aerometeorograph: Category : engineering; A self-recording instrument used on aircraft for the simultaneous recording of atmospheric pressure, temperature, and humidity.
aerometer: Category : engineering; An instrument to ascertain the weight or density of air or other gases.
aerophotography: Category : engineering(see aerial photography)
aerosol generator: Category : mechanical engineering; A mechanical means of producing a system of dispersed phase and dispersing medium, that is, an aerosol.
aerospace engineering: Category : engineering; Engineering pertaining to the design and construction of aircraft and space vehicles and of power units, and to the special problems of flight in both the earth's atmosphere and space, as in the flight of air vehicles and in the launching, guidance, and c
aerospace industry: Category : engineering; Industry concerned with the use of vehicles in both the earth's atmosphere and space.
aerostatic balance: Category : engineering; An instrument for weighing air.
aerosurvey: Category : engineering(see aerial survey)
aerotrain: Category : engineering; A train that is propelled by a fan jet engine and floats on a cushion of low-pressure air, traveling at speeds up to 267 miles (430 kilometers) per hour.
aesthesiometer: Category : engineering(see esthesiometer)
affreightment: Category : industrial engineering; The lease of a vessel for the transportation of goods.
after top dead center: Category : mechanical engineering; The position of the piston after reaching the top of its stroke in an automotive engine.
afterboil: Category : mechanical engineering; In an automotive engine, coolant boiling after the engine has stopped because of the inability of the engine at rest to dissipate excess heat.
afterburning: Category : mechanical engineering; Combustion in an internal combustion engine following the maximum pressure of explosion.
aftercondenser: Category : mechanical engineering; A condenser in the second stage of a two-stage ejector, used in steam power plants, refrigeration systems, and air conditioning systems.
aftercooler: Category : mechanical engineering; A heat exchanger which cools air that has been compressed, used on turbocharged engines.
aftercooling: Category : mechanical engineering; The cooling of a gas after its compression.
afterfilter: Category : mechanical engineering; In an air-conditioning system, a high-efficiency filter located near a terminal unit. Also known as final filter.
afterrunning: Category : mechanical engineering; In an automotive engine, continued operation of the engine after the ignition switch is turned off. Also known as dieseling, run-on.
agger: Category : civil engineering; A material used for road fill over low ground.
aggregate bin: Category : engineering; A structure designed for storing and dispensing dry granular construction materials such as sand, crushed stone, and gravel, usually has a hopperlike bottom that funnels the material to a gate under the structure.
aggregate interlock: Category : engineering; The projection of aggregate particles or portions thereof from one side of a joint or crack in concrete into recesses in the other side so as to effect load transfer in compression and shear, and to maintain mutual alignment.
aggregate production scheduling: Category : industrial engineering; A type of planning at a broad level without consideration of individual products and activities in order to develop a program of output that will meet future demand under given constraints.
aggressive carbon dioxide: Category : chemical engineering; The carbon dioxide dissolved in water in excess of the amount required to precipitate a specified concentration of calcium ions as calcium carbonate, used as a measure of the corrosivity and scaling properties of water.
agile manufacturing: Category : industrial engineering; Operations that can be rapidly reconfigured to satisfy changing market demands.
agitating speed: Category : mechanical engineering; The rate of rotation of the drum or blades of a truck mixer or other device used for agitation of mixed concrete.
agitating truck: Category : mechanical engineering; A vehicle carrying a drum or agitator body, in which freshly mixed concrete can be conveyed from the point of mixing to that of placing, the drum being rotated continuously to agitate the contents.
agitator: Category : mechanical engineering; A device for keeping liquids and solids in liquids in motion by mixing, stirring, or shaking.
agitator body: Category : mechanical engineering; A truck-mounted drum for transporting freshly mixed concrete, rotation of internal paddles or of the drum prevents the setting of the mixture prior to delivery.
agricultural pipe drain: Category : civil engineering; A system of porous or perforated pipes laid in a trench filled with gravel or the like, used for draining subsoil.
agricultural robot: Category : control systems; A robot used to pick and harvest farm products and fruits.
AGV: Category : industrial engineering(see automated guided vehicle)
aided tracking: Category : engineering; A system of radar-tracking a target signal in bearing, elevation, or range, or any combination of these variables, in which the rate of motion of the tracking equipment is machine-controlled in collaboration with an operator so as to minimize tracking err
aided-tracking mechanism: Category : engineering; A device consisting of a motor and variable-speed drive which provides a means of setting a desired tracking rate into a director or other fire-control instrument, so that the process of tracking is carried out automatically at the set rate until it is ch
aided-tracking ratio: Category : engineering; The ratio between the constant velocity of the aided-tracking mechanism and the velocity of the moving target.
aiguille: Category : engineering; A slender form of drill used for boring or drilling a blasthole in rock.
aiming circle: Category : engineering; An instrument for measuring angles in azimuth and elevation in connection with artillery firing and general topographic work, equipped with fine and coarse azimuth micrometers and a magnetic needle.
aiming screws: Category : mechanical engineering; On an automotive vehicle, spring-loaded screws designed to secure headlights to a support frame and permit aiming of the headlights in horizontal and vertical planes.
air: Category : mechanical engineering(see air-injection reactor)
air aspirator valve: Category : mechanical engineering; On certain automotive engines, a one-way valve installed on the exhaust manifold to allow air to enter the exhaust system, provides extra oxygen to convert carbon monoxide to carbon dioxide. Also known as gulp valve.
air bag: Category : mechanical engineering; An automotive vehicle passenger safety device consisting of a passive restraint in the form of a bag which is automatically inflated with gas to provide cushioned protection against the impact of a collision.
air belt: Category : mechanical engineering; The chamber which equalizes the pressure that is blasted into the cupola at the tuyeres.
air bind: Category : engineering; The presence of air in a conduit or pump which impedes passage of the liquid.
air bleeder: Category : mechanical engineering; A device, such as a needle valve, for removing air from a hydraulic system.
air brake: Category : mechanical engineering; An energy-conversion mechanism activated by air pressure and used to retard, stop, or hold a vehicle or, generally, any moving element.
air breaking: Category : engineering(see airblasting)
air bypass valve: Category : mechanical engineering; Also known as diverter valve.
air cap: Category : mechanical engineering; A device used in thermal spraying which directs the air pattern for purposes of atomization.
air casing: Category : engineering; A metal casing surrounding a pipe or reservoir and having a space between to prevent heat transmission.
air chamber: Category : mechanical engineering; A pressure vessel, partially filled with air, for converting pulsating flow to steady flow of water in a pipeline, as with a reciprocating pump.
air change: Category : engineering; A measure of the movement of a given volume of air in or out of a building or room in a specified time period, usually expressed in cubic feet per minute.
air check: Category : engineering acoustics; A recording made of a live radio broadcast for filing purposes at the broadcasting facility.
air classifier: Category : mechanical engineering; A device to separate particles by size through the action of a stream of air. Also known as air elutriator.
air cleaner: Category : engineering; Any of various devices designed to remove particles and aerosols of specific sizes from air, examples are screens, settling chambers, filters, wet collectors, and electrostatic precipitators.
air compressor: Category : mechanical engineering; A machine that increases the pressure of air by increasing its density and delivering the fluid against the connected system resistance on the discharge side.
air conditioner: Category : mechanical engineering; A mechanism primarily for comfort cooling that lowers the temperature and reduces the humidity of air in buildings.
air conditioning: Category : mechanical engineering; The maintenance of certain aspects of the environment within a defined space to facilitate the function of that space, aspects controlled include air temperature and motion, radiant heat level, moisture, and concentration of pollutants such as dust, micro
air conveyor: Category : mechanical engineering(see pneumatic conveyor)
air cooling: Category : mechanical engineering; Lowering of air temperature for comfort, process control, or food preservation.
air course: Category : building construction(see airway)
air curtain: Category : mechanical engineering; A stream of high-velocity temperature-controlled air which is directed downward across an opening, it excludes insects, exterior drafts, and so forth, prevents the transfer of heat across it, and permits air-conditioning of a space with an open entrance.
air cushion: Category : mechanical engineering; A mechanical device using trapped air to arrest motion without shock.
air cycle: Category : mechanical engineering; A refrigeration cycle characterized by the working fluid, air, remaining as a gas throughout the cycle rather than being condensed to a liquid, used primarily in airplane air conditioning.
air cylinder: Category : mechanical engineering; A cylinder in which air is compressed by a piston, compressed air is stored, or air drives a piston.
air density: Category : mechanics; The mass per unit volume of air.
air diffuser: Category : building construction; An air distribution outlet, usually located in the ceiling and consisting of deflecting vanes discharging supply air in various directions and planes, and arranged to promote mixing of the supplied air with the air already in the room.
air diving: Category : engineering; A type of diving in which the diver's breathing medium is a normal atmospheric mixture of oxygen and nitrogen, limited to depths of 190 feet (58 meters).
air drain: Category : civil engineering; An empty space left around the external foundation wall of a building to prevent the earth from lying against it and causing dampness.
air drill: Category : mechanical engineering; A drill powered by compressed air.
air drying: Category : engineering; Removing moisture from a material by exposure to air to the extent that no further moisture is released on contact with air, important in lumber manufacture.
air duct: Category : engineering(see airflow duct)
air ejector: Category : mechanical engineering; A device that uses a fluid jet to remove air or other gases, as from a steam condenser.
air eliminator: Category : mechanical engineering; In a piping system, a device used to remove air from water, steam, or refrigerant.
air elutriator: Category : mechanical engineering(see air classifier)
air engine: Category : mechanical engineering; An engine in which compressed air is the actuating fluid.
air entrainment: Category : engineering; The inclusion of minute bubbles of air in cement or concrete through the addition of some material during grinding or mixing to reduce the surface tension of the water, giving improved properties for the end product.
air escape: Category : design engineering; A device that is fitted to a pipe carrying a liquid for releasing excess air, it contains a valve that controls air release while preventing loss of liquid.
air filter: Category : engineering; A device that reduces the concentration of solid particles in an airstream to a level that can be tolerated in a process or space occupancy, a component of most systems in which air is used for industrial processes, ventilation, or comfort air conditionin
air flotation: Category : chemical engineering(see dissolved air flotation)
air grating: Category : building construction; A fixed metal grille on the exterior of a building through which air is brought into or discharged from the building for purposes of ventilation.
air hammer: Category : mechanical engineering(see pneumatic hammer)
air heater: Category : mechanical engineering(see air preheater)
air hoist: Category : mechanical engineering; A lifting tackle or tugger constructed with cylinders and pistons for reciprocating motion and air motors for rotary motion, all powered by compressed air. Also known as pneumatic hoist.
air horn: Category : mechanical engineering; In an automotive engine, the upper portion of the carburetor barrel through which entering air passes in quantities controlled by the choke plate and the throttle plate.
air horsepower: Category : mechanical engineering; The theoretical (minimum) power required to deliver the specified quantity of air under the specified pressure conditions in a fan, blower, compressor, or vacuum pump. Abbreviated air hp.
air hp: Category : mechanical engineering(see air horsepower)
air inlet: Category : mechanical engineering; In an air-conditioning system, a device through which air is exhausted from a room or building.
air knife: Category : engineering; A device that uses a thin, flat jet of air to remove the excess coating from freshly coated paper.
air lift: Category : mechanical engineering(see air-lift pump); Equipment for lifting slurry or dry powder through pipes by means of compressed air.
air meter: Category : engineering; A device that measures the flow of air, or gas, expressed in volumetric or weight units per unit time. Also known as airometer.
air mileage indicator: Category : engineering; An instrument on an airplane which continuously indicates mileage through the air.
air mileage unit: Category : engineering; A device which derives continuously and automatically the air distance flown, and feeds this information into other units, such as an air mileage indicator.
air monitoring: Category : civil engineering; A practice of continuous air sampling by various levels of government or particular industries.
air motor: Category : mechanical engineering; A device in which the pressure of confined air causes the rotation of a rotor or the movement of a piston.
air nozzle: Category : mechanical engineering; In an automotive engine, a device for supplying air to the air-injection reactor.
air outlet: Category : mechanical engineering; In an air-conditioning system, a device at the end of a duct through which air is supplied to a space.
air pocket: Category : engineering; An air-filled space that is normally occupied by a liquid. Also known as air trap.
air preheater: Category : mechanical engineering; A device used in steam boilers to transfer heat from the flue gases to the combustion air before the latter enters the furnace. Also known as air heater, air-heating system.
air propeller: Category : mechanical engineering; A rotating fan for moving air.
air pump: Category : mechanical engineering; A device for removing air from an enclosed space or for adding air to an enclosed space.
air puncher: Category : engineering; A machine consisting essentially of a reciprocating chisel or pick, driven by air.
air purge: Category : mechanical engineering; Removal of particulate matter from air within an enclosed vessel by means of air displacement.
air receiver: Category : mechanical engineering; A vessel designed for compressed-air installations that is used both to store the compressed air and to permit pressure to be equalized in the system.
air register: Category : engineering; A device attached to an air-distributing duct for the purpose of controlling the discharge of air into the space to be heated, cooled, or ventilated.
air regulator: Category : mechanical engineering; A device for regulating airflow, as in the burner of a furnace.
air reheater: Category : mechanical engineering; In a heating system, any device used to add heat to the air circulating in the system.
air release valve: Category : mechanical engineering; A valve, usually manually operated, which is used to release air from a water pipe or fitting.
air resistance: Category : mechanics; Wind drag giving rise to forces and wear on buildings and other structures.
air ring: Category : engineering; In plastics forming, a circular manifold which distributes an even flow of cool air into a hollow tubular form passing through the manifold.
air sampling: Category : engineering; The collection and analysis of samples of air to measure the amounts of various pollutants or other substances in the air, or the air's radioactivity.
air scoop: Category : design engineering; An air-duct cowl projecting from the outer surface of an aircraft or automobile, which is designed to utilize the dynamic pressure of the airstream to maintain a flow of air.
air screw: Category : mechanical engineering; A screw propeller that operates in air.
air separator: Category : mechanical engineering; A device that uses an air current to separate a material from another of greater density or particles from others of greater size.
air shaft: Category : building construction; An open space surrounded by the walls of a building or buildings to provide ventilation for windows. Also known as air well.
air shot: Category : engineering; A shot prepared by loading (charging) so that an air space is left in contact with the explosive for the purpose of lessening its shattering effect.
air space: Category : engineering; An enclosed space containing air in a wall for thermal insulation.
air spring: Category : mechanical engineering; A spring in which the energy storage element is air confined in a container that includes an elastomeric bellows or diaphragm.
air starting valve: Category : mechanical engineering; A device that admits compressed air to an air starter.
air stripping: Category : chemical engineering; The process of bubbling air through water to remove volatile organic substances from the water.
air surveillance: Category : engineering; Systematic observation of the airspace by visual, electronic, or other means, primarily for identifying all aircraft in that airspace, and determining their movements.
air surveillance radar: Category : engineering; Radar of moderate range providing position of aircraft by azimuth and range data without elevation data, used for air-traffic control.
air survey: Category : engineering(see aerial survey)
air sweetening: Category : chemical engineering; A process in which air or oxygen is used to oxidize lead mercaptides to disulfides instead of using elemental sulfur.
air system: Category : mechanical engineering; A mechanical refrigeration system in which air serves as the refrigerant in a cycle comprising compressor, heat exchanger, expander, and refrigerating core.
air thermometer: Category : engineering; A device that measures the temperature of an enclosed space by means of variations in the pressure or volume of air contained in a bulb placed in the space.
air toxics: Category : engineering(see hazardous air pollutants)
air valve: Category : mechanical engineering; A valve that automatically lets air out of or into a liquid-carrying pipe when the internal pressure drops below atmospheric.
air well: Category : building construction(see air shaft)
air-actuated: Category : engineering; Powered by compressed air.
air-arc furnace: Category : engineering; An arc furnace designed to power wind tunnels, the air being superheated to 20,000 K and expanded to emerge at supersonic speeds.
air-assist forming: Category : engineering; A plastics thermoforming method in which air pressure is used to partially preform a sheet before it enters the mold.
air-atomizing oil burner: Category : engineering; An oil burner in which a stream of fuel oil is broken into very fine droplets through the action of compressed air.
airblasting: Category : engineering; A blasting technique in which air at very high pressure is piped to a steel shell in a shot hole and discharged. Also known as air breaking.
airborne collision warning system: Category : engineering; A system such as a radar set or radio receiver carried by an aircraft to warn of the danger of possible collision.
airborne detector: Category : engineering; A device, transported by an aircraft, whose function is to locate or identify an air or surface object.
airborne electronic survey control: Category : engineering; The airborne portion of very accurate positioning systems used in controlling surveys from aircraft.
airborne intercept radar: Category : engineering; Airborne radar used to track and (
airborne magnetometer: Category : engineering; An airborne instrument used to measure the magnetic field of the earth.
airborne profile recorder: Category : engineering; An electronic instrument that emits a pulsed-type radar signal from an aircraft to measure vertical distances between the aircraft and the earth's surface. Abbreviated APR. Also known as terrain profile recorder (TPR).
airborne radar: Category : engineering; Radar equipment carried by aircraft to assist in navigation by pilotage, to determine drift, and to locate weather disturbances, a very important use is locating other aircraft either for avoidance or attack.
airborne waste: Category : engineering; Vapors, gases, or particulates introduced into the atmosphere by evaporation, chemical, or combustion processes, a frequent cause of smog and an irritant to eyes and breathing passages.
air-bound: Category : engineering; Of a pipe or apparatus, containing a pocket of air that prevents or reduces the desired liquid flow.
air-breathing: Category : mechanical engineering; Of an engine or aerodynamic vehicle, required to take in air for the purpose of combustion.
Airco-Hoover sweetening: Category : chemical engineering; Removal of mercaptans from gasoline by caustic and water washes, then heating the dried gasoline and passing it with some oxygen through a reactor containing a slurry of diatomaceous earth impregnated with copper chloride, the oxygen regenerates the catal
air-compressor unloader: Category : mechanical engineering; A device for control of air volume flowing through an air compressor.
air-compressor valve: Category : mechanical engineering; A device for controlling the flow into or out of the cylinder of a compressor.
air-cooled engine: Category : mechanical engineering; An engine cooled directly by a stream of air without the interposition of a liquid medium.
air-cooled heat exchanger: Category : mechanical engineering; A finned-tube (extended-surface) heat exchanger with hot fluids inside the tubes, and cooling air that is fan-blown (forced draft) or fan-pulled (induced draft) across the tube bank.
aircraft detection: Category : engineering; The sensing and discovery of the presence of aircraft, major techniques include radar, acoustical, and optical methods.
aircraft impactor: Category : engineering; An instrument carried by an aircraft for the purpose of obtaining samples of airborne particles.
air-cure: Category : chemical engineering; To vulcanize at ordinary room temperatures, or without the aid of heat.
air-cushion vehicle: Category : mechanical engineering; A transportation device supported by low-pressure, low-velocity air capable of traveling equally well over water, ice, marsh, or relatively level land. Also known as ground-effect machine (GEM), hovercraft.
air-cut: Category : engineering; Referring to the inadvertent mechanical incorporation of air into a liquid system.
air-distributing acoustical ceiling: Category : building construction; A suspended acoustical ceiling in which the board or tile is provided with small, evenly distributed mechanical perforations, designed to provide a desired flow of air from a pressurized plenum above.
airdraulic: Category : mechanical engineering; Combining pneumatic and hydraulic action for operation.
air-exhaust ventilator: Category : mechanical engineering; Any air-exhaust unit used to carry away dirt particles, odors, or fumes.
airfield: Category : civil engineering; The area of an airport for the takeoff and landing of airplanes.
airflow duct: Category : engineering; A pipe, tube, or channel through which air moves into or out of an enclosed space. Also known as air duct.
airflow orifice: Category : engineering; An opening through which air moves out of an enclosed space.
airflow pipe: Category : engineering; A tube through which air is conveyed from one location to another.
air-fuel mixture: Category : mechanical engineering; In a carbureted gasoline engine, the charge of air and fuel that is mixed in the appropriate ratio in the carburetor and subsequently fed into the combustion chamber.
air-handling system: Category : mechanical engineering; An air-conditioning system in which an air-handling unit provides part of the treatment of the air.
air-handling unit: Category : mechanical engineering; A packaged assembly of air-conditioning components (coils, filters, fan humidifier, and so forth) which provides for the treatment of air before it is distributed.
air-heating system: Category : mechanical engineering(see air preheater)
air-injection reactor: Category : mechanical engineering; A unit installed in an automotive engine which mixes fresh air with hot exhaust gases in the exhaust manifold to react with any gasoline that has escaped unburned from the cylinders. Abbreviated AIR.
air-injection system: Category : mechanical engineering; A device that uses compressed air to inject the fuel into the cylinder of an internal combustion engine. Also known as thermactor.
air-inlet valve: Category : mechanical engineering; In a heating/air-conditioning system of a motor vehicle, a valve in the plenum blower assembly that permits selection of either inside or outside air.
air-knife coating: Category : engineering; An even film of coating left on paper after treatment with an air knife.
air-lance: Category : engineering; To direct a pressurized-air stream to remove unwanted accumulations, as in boiler-wall cleaning.
airless spraying: Category : engineering; The spraying of paint by means of high fluid pressure and special equipment. Also known as hydraulic spraying.
air-lift hammer: Category : mechanical engineering; A gravity drop hammer used in closed die forging in which the ram is raised to its starting point by means of an air cylinder.
air-lift pump: Category : mechanical engineering; A device composed of two pipes, one inside the other, used to extract water from a well, the lower end of the pipes is submerged, and air is delivered through the inner pipe to form a mixture of air and water which rises in the outer pipe above the water
air-line lubricator: Category : mechanical engineering(see line oiler)
air-lock strip: Category : building construction; The weather stripping which is fastened to the edges of each wing of a revolving door.
air-mixing plenum: Category : mechanical engineering; In an air-conditioning system, a chamber in which the recirculating air is mixed with air from outdoors.
airometer: Category : engineering(see air meter); An apparatus for both holding air and measuring the quantity of air admitted into it.
air-permeability test: Category : engineering; A test for the measurement of the fineness of powdered materials, such as portland cement.
airplane flare: Category : engineering; A flare, often magnesium, that is dropped from an airplane to illuminate a ground area, a small parachute decreases the rate of descent.
air-pollution control: Category : engineering; A practical means of treating polluting sources to maintain a desired degree of air cleanliness.
airport: Category : civil engineering; A terminal facility used for aircraft takeoff and landing and including facilities for handling passengers and cargo and for servicing aircraft. Also known as aerodrome.
airport engineering: Category : civil engineering; The planning, design, construction, and operation and maintenance of facilities providing for the landing and takeoff, loading and unloading, servicing, maintenance, and storage of aircraft.
airproof: Category : engineering(see airtight)
air-raid shelter: Category : civil engineering; A chamber, often underground, provided with living facilities and food, for sheltering people against air attacks.
air-seasoned: Category : engineering; Treated by exposure to air to give a desired quality.
Airslide conveyor: Category : mechanical engineering; An air-activated gravity-type conveyor, of the Fuller Company, using low-pressure air to aerate or fluidize pulverized material to a degree which will permit it to flow on a slight incline by the force of gravity.
airspeed head: Category : engineering; Any instrument or device, usually a pitot tube, mounted on an aircraft for receiving the static and dynamic pressures of the air used by the airspeed indicator.
airspeed indicator: Category : engineering; A device that computes and displays the speed of an aircraft relative to the air mass in which the aircraft is flying.
air-standard cycle: Category : thermodynamics; A thermodynamic cycle in which the working fluid is considered to be a perfect gas with such properties of air as a volume of 12.4 cubic feet per pound at 14.7 pounds per square inch (approximately 0.7756 cubic meter per kilogram at 101.36 kilopascals) an
air-standard engine: Category : mechanical engineering; A heat engine operated in an air-standard cycle.
air-supply mask: Category : engineering(see air-tube breathing apparatus)
air-suspension encapsulation: Category : chemical engineering; A technique for microencapsulation of various types of solid particles, the particles undergo a series of cycles in which they are first suspended by a vertical current of air while they are sprayed with a solution of coating material, and are then moved
air-suspension system: Category : mechanical engineering; Parts of an automotive vehicle that are intermediate between the wheels and the frame, and support the car body and frame by means of a cushion of air to absorb road shock caused by passage of the wheels over irregularities.
airtight: Category : engineering; Not permitting the passage of air. Also known as airproof.
air-to-air resistance: Category : civil engineering; The resistance provided by the wall of a building to the flow of heat.
air-tube breathing apparatus: Category : engineering; A device consisting of a smoke helmet, mask, or mouthpiece supplied with fresh air by means of a flexible tube. Also known as air-supply mask.
air-tube clutch: Category : mechanical engineering; A clutch fitted with a tube whose inflation causes the clutch to engage, and deflation, to disengage.
air-water jet: Category : engineering; A jet of mixed air and water which leaves a nozzle at high velocity, used in cleaning the surfaces of concrete or rock.
air-water storage tank: Category : engineering; A water storage tank in which the air above the water is compressed.
airway: Category : building construction; A passage for ventilation between thermal insulation and roof boards.
Airy points: Category : engineering; The points at which a horizontal rod is optionally supported to avoid its bending.
Airy stress function: Category : mechanics; A biharmonic function of two variables whose second partial derivatives give the stress components of a body subject to a plane strain.
aisleway: Category : civil engineering; A passage or walkway within a factory, storage building, or shop permitting the flow of inside traffic.
Aitken dust counter: Category : engineering; An instrument for determining the dust content of the atmosphere. Also known as Aitken nucleus counter.
Aitken nucleus counter: Category : engineering(see Aitken dust counter)
alarm gage: Category : engineering; A device that actuates a signal either when the steam pressure in a boiler is too high or when the water level in a boiler is too low.
alarm system: Category : engineering; A system which operates a warning device after the occurrence of a dangerous or undesirable condition.
alarm valve: Category : engineering; A device that sounds an alarm when water flows in an automatic sprinkler system.
albedometer: Category : engineering; An instrument used for the measurement of the reflecting power, that is, the albedo, of a surface.
Alberger process: Category : chemical engineering; A method of manufacturing salt by heating brine at high pressure and passing it to a graveler which removes calcium sulfate, the salt crystallizes as the pressure is reduced and thus is separated from the brine.
alcohol thermometer: Category : engineering; A liquid-in-glass thermometer that uses ethyl alcohol as its working substance.
alcoholimeter: Category : engineering(see alcoholometer)
alcoholmeter: Category : engineering(see alcoholometer)
alcoholometer: Category : engineering; A device, such as a form of hydrometer, that measures the quantity of an alcohol contained in a liquid. Also known as alcoholimeter, alcoholmeter.
aligning drift: Category : mechanical engineering; A rod or bar that is used for aligning parts during assembly.
alignment correction: Category : engineering; A correction applied to the measured length of a line to allow for not holding the tape exactly in a vertical plane of the line.
alignment pin: Category : design engineering; Pin in the center of the base of an octal, loctal, or other tube having a single vertical projecting rib that aids in correctly inserting the tube in its socket.
alignment wire: Category : civil engineering(see ground wire)
alkali ion diode: Category : engineering; In testing for leaks, a device which senses the presence of halogen gases by the use of positive ions of alkali metal on the heated diode surfaces.
alkaline wash: Category : chemical engineering; The removal of impurities from kerosine,used for illuminating purposes, by caustic soda solution.
Alkar process: Category : chemical engineering; Catalytic alkylation of aromatic hydrocarbons with olefins to produce alkylaromatics, for example, production of ethylbenzene from benzene and ethylene.
alkylate bottom: Category : chemical engineering; Residue from fractionation of total alkylate which boils at a higher temperature than aviation gasolines.
alkylation: Category : chemical engineering; A refinery process for chemically combining isoparaffin with olefin hydrocarbons.
allège: Category : building construction; A part of a wall which is thinner than the rest, especially the spandrel under a window.
Allen screw: Category : design engineering; A screw or bolt which has an axial hexagonal socket in its head.
Allen wrench: Category : design engineering; A wrench made from a straight or bent hexagonal rod, used to turn an Allen screw.
alligator shears: Category : engineering; A cutting tool with a fixed lower blade and a movable upper blade (shearing arm) that moves in an arc around a fulcrum pin, used mainly for shearing applications that do not require great accuracy.
alligator wrench: Category : design engineering; A wrench having fixed jaws forming a V, with teeth on one or both jaws.
allocate: Category : industrial engineering; To assign a portion of a resource to an activity.
allowable bearing value: Category : civil engineering; The maximum permissible pressure on foundation soil that provides adequate safety against rupture of the soil mass or movement of the foundation of such magnitude as to impair the structure imposing the pressure. Also known as allowable soil pressure.
allowable load: Category : mechanics; The maximum force that may be safely applied to a solid, or is permitted by applicable regulators.
allowable soil pressure: Category : civil engineering(see allowable bearing value)
allowable stress: Category : mechanics; The maximum force per unit area that may be safely applied to a solid.
allowance: Category : design engineering; An intentional difference in sizes of two mating parts, allowing clearance usually for a film of oil, for running or sliding fits.
allowed hours: Category : industrial engineering(see standard hour)
allowed time: Category : industrial engineering; Amount of time allowed each employee for personal needs during a work cycle.
all-translational system: Category : control systems; A simple robotic system in which there is no rotation of the robot or its components during movements of the robot's body.
all-weather airport: Category : civil engineering; An airport with facilities to permit the landing of qualified aircraft and aircrewmen without regard to operational weather limits.
alpha-ray vacuum gage: Category : engineering; An ionization gage in which the ionization is produced by alpha particles emitted by a radioactive source, instead of by electrons emitted from a hot filament, used chiefly for pressures from 10⁻³ to 10 torrs. Also known as alphatron.
alphatron: Category : engineering(see alpha-ray vacuum gage)
alt: Category : engineering(see altitude)
altazimuth: Category : engineering; An instrument equipped with both horizontal and vertical graduated circles, for the simultaneous observation of horizontal and vertical directions or angles. Also known as astronomical theodolite, universal instrument.
alt-azimuth mounting: Category : engineering(see altitude-azimuth mounting)
alternate energy: Category : engineering; Any source of energy other than fossil fuels that is used for constructive purposes.
alternating current: Category : electricity; Electric current that reverses direction periodically, usually many times per second. Abbreviated ac.
alternating stress: Category : mechanics; A stress produced in a material by forces which are such that each force alternately acts in opposite directions.
alternating-current welder: Category : engineering; A

exaVAR

Dictionary of Engineering