A symbol of merit, often abbreviated Q, for an energy-storing device, resonant system, or tuned circuit.
A term given to a device which applies an artificial force on the control column of a power-controlled aircraft proportional to the aerodynamic loads on the control surfaces, thereby simulating the natural feel of the aircraft throughout its speed range.
One based on helium (98.2% He, 1.8% butane) widely used in gas-flow counting.
A trade name for a special nylon with silken properties when spun into fiber.
An algebraic equation of the second degree (ax² + bx + c = 0), whose solution is
The relation between two waves of the same frequency but one-quarter of a cycle (90°) out of phase, as in TV color difference signals
Quadrature amplitude modulation
A modulation system involving phase and amplitude modulation of a carrier, used in microwave and satellite communication links.
A term used in the two reaction theory of synchronous machines to denote the ratio which the synchronous reactance drop produced by the quadrature component of the armature current bears to actual value of quadrature component.
A transformer designed so that secondary emf is 90° displaced from primary emf
An early type of lightweight, four-wheeled automobile using bicycle wheels and a frame of steel tubes.
A four-sided polygon
Quadrilateral speed-time curve
A simplified form of speed-time curve used in making preliminary calculations regarding energy consumption and average speed of railway trains. The acceleration and coasting portions of the curve are sloping straight lines and the braking portion is neglected, so that the curve becomes a quadrilateral
A network with two input and two output terminals. A balanced wave-filter section
A term describing an atom with four electrons in its valency shell
A system of sound transmission using a minimum of four speakers fed by four, or sometimes three, separate channels.
A steam engine in which the steam is expanded successively in four cylinders of increasing size, all working on the same crankshaft
A point on a concentration-pressure-temperature diagram at which a two-component system can exist in four phases
Videotape recording and reproduction system using four rotating heads to produce transverse tracks on two-inch wide magnetic tape
A system of Morse telegraphy arranged for simultaneous independent transmission of two messages in each direction over a single circuit
A collection of charges such that the potential at a point distance r from their center of mass may be expressed by an infinite series of terms in inverse powers of r. The inverse third power term is the quadrupole potential
The moment derived from the series expansion of charges multiplied by space co-ordinates. The sum of the quadratic terms is the quadrupole moment, which is possessed by most metals.
Radiator producing a sound field of two adjacent dipoles in antiphase. the eddies in a subsonic jet of gas are quadrupoles
An evaluation of a flight article or its equivalent to verify that it functions correctly under the specified conditions of space-flight; normally the test conditions are more severe than those expected
Identification of the constituents of a sample without regard to their relative amounts. It often refers to elemental analysis, but may also refer to the detection of acid-base or redox properties in a sample
Conformance to requirements in relation to a degree of excellence.
In sound reproduction, the degree to which a sample of reproduced sound resembles a sample of the original sound. The general description of freedom from various types of acoustic distortion in sound-reproducing systems.
The timbre or quality of a note which depends upon the number and magnitude of harmonics of the fundamental.
The condition of a saturated vapor, particularly steam, expressed as the ratio per cent of the vaporized portion to the total weight of liquid and vapor.
In radiography, an indication of the approximate penetrating power. Higher voltages produce higher quality X-rays of shorter wavelength and greater penetration. The term dates from before the nature of X-rays was completely understood.
Ways of managing materials, components and products so as to ensure high-quality control of manufactured products at all levels
The argument of the cumulative distribution function corresponding to a specified probability; (of a sample) the value below which occur a specified proportion of the observations in the ordered set of observations.
A trade name for a machine which analyses material surfaces for microstructural variables such as grain size diameter, orientation etc.Based originally on the optical microscope, extended to electron optical examination. Uses computer techniques to perform statistical analyses based on stereological methods.
Identification of the relative amounts of substances making up a sample. It usually refers to elemental analysis, but may refer to any constituent of the sample. In addition to chemical methods, virtually every physical property can be a basis for some analytical method, and spectroscopic and electrochemical techniques are particularly often employed.
Quantity of electricity
A product of the flow of electricity (current) and time during which it flows. The term may also refer to a charge of electricity.
Quantity of light
A product of luminous flux and time during which it is maintained; usually stated in lumen-hours.
Quantity of radiation
Product of intensity and time of X-ray radiation. Not measured by energy, but by energy density and a coefficient depending on ability to cause ionization.
One who measures up from drawings and prepares a bill (or schedule) of quantities showing the content of each item. This is then used by contractors for estimating. The quantity surveyor also periodically measures and assesses the value of the work done.
In quantum theory, the division of energy of a system into discrete units (quanta), so that continuous infinitesimal changes are excluded.
In Pulse-code modulation, the division of the amplitude range of a continuously variable signal, e.g., speech or video, into discrete levels for the purposes of sampling and coding.
The distortion that arises in the mapping of a continuous signal on to a number of discrete levels so that it may be coded for digital transmission.
Quantization distortion unit
A measure of Quantization distortion equivalent to the transition from analogue to 64 Kbits--1 A-law digital code and back again.
Noise introduced into a circuit using Pulse-code modulation because there are too few levels of quantitation to describe the waveform accurately.
An instrument showing by spectrographical analysis the percentages of the various metals present in a metallic sample.
general term for the indivisible unit of any form of physical energy; in particular the photon, the discrete amount of electromagnetic radiation energy, its magnitude being hv where v is the frequency and h is Planck’s constant.
An interval on a measuring scale, fractions of which are considered insignificant.
(QCD) The theory of strong interactions between elementary particles including the interaction that binds protons and neutrons to form a nucleus. It assumes that strongly interacting particles are made of quarks and that gluons bind the quarks together.
The number of electrons released in a photocell per photon of incident radiation of specified wavelength.
(QED) A relativistic quantum theory of electromagnetic interactions. It provides a description of the interaction of electrons, muons and photons and hence the underlying theory of all electromagnetic phenomena.
The study of the amplification or generation of microwave power in solid crystals, governed by quantum mechanical laws.
Quantum field theory
The overall theory of fundamental particles and their interactions. Each type of particle is represented by appropriate operators which obey certain commutation laws. Particles are the quanta of fields in the same way as photons are the quanta of the electromagnetic field. So gluon fields and Intermediate vector boson fields can be related to strong and weak interactions. Quantum field theory accounts for the Lamb shift.
The effect in which Hall resistivity changes by steps so that it is a fraction of h/e² where h is Planck’s constant and e is the electronic charge. Observed in two-dimensional semiconductors (e.g., Metal-oxide-silicon) at high magnetic fields and ultra-low temperatures.
A generally accepted theory replacing classical mechanics for microscopic phenomena. Quantum mechanics also gives results consistent with classical mechanics for macroscopic phenomena. Two equivalent formalisms have been developed matrix mechanics (developed by W. Heisenberg) and wave mechanics (developed by E. Schrödinger). The theory accounts for a very wide range of physical phenomena.
One of a set of numbers describing possible quantum states of a system, e.g., nuclear spin.
Statistics of the distribution of particles of a specified type in relation to their energies, the latter being quantized.
The theory developed from Planck’s law to account for black-body radiation, the Photoelectric effect and the Compton effect and to form the Bohr model of the atom and its modification by Sommerfeld.
Voltage through which an electron must be accelerated to acquire the energy corresponding to a particular quantum
A nano-structure proportioned like a wire so that electron behavior is strongly constrained by quantum mechanical effects in two dimensions.
The ratio of the number of photon-induced reactions occurring to the total number of incident photons.
A dome-like structure of folded sedimentary rocks which dip uniformly outward from a central point.
A type of fundamental particle that forms the constituents of Hadrons. There are currently believed to be six types (or Flavors) of quarks (and their antiquarks) up, down, charm, strange, top, bottom. In quark theory, the baryon is composed of three quarks of different color, an antibaryon is composed of three antiquarks, and a meson is composed of a quark and an antiquark. No quark has been observed in isolation.
An open working or pit for granite, building-stone, slate or other rock.
An underground working in a coal mine for stone to fill the goaf. distinction between quarry and mine is somewhat blurred in law, but usage implies surface workings.
A term applied to a building-stone whose face is hammer-dressed before leaving the quarry.
A term applied to stones which are roughly squared before leaving the quarry.
Quarry stone bond
A term applied to the arrangement of stones in rubble masonry.
The common unglazed, machine-made paving tile not less than .75′ (20 mm) in thickness, Also called promenade tile.
One-quarter of a gallon, or two pints (UK 1.14 litre, US 0.946 litre in liquid measure, 1.1 litre in dry measure).
The phase of the Moon at quadrature. The first quarter occurs when the longitude of the Moon exceeds that of the Sun by 90°, the last quarter when the excess is 270°. The two other quarters are the new Moon and full Moon.
The fourth part of a hundredweight, equivalent to 28 (or in US 25) pounds avoirdupois.
The ordinary brickwork bond obtained by using a 2.25′ (57 mm) closer.
A term applied to a book having its back and part of its sides covered in one material and the rest of its sides in another.
A type of shortened bumper designed to give a car a sporting image. Instead of extending around the full width of the car, short bumper sections around the left-hand and right-hand corners leave the center unprotected. This type of bumper was popular on certain sports models manufactured by Opel and Ford in the 1970s
The point on the Chord line at one quarter of the chord length behind the leading edge. Sweepback is usually quoted by the angle between the line of the quarter-chord points and the normal to the aircraft fore-and-aft center-line.
Quarter-elliptic leaf spring
A cantilevered half of a semi-elliptic leaf spring, rigidly attached to a vehicle at its major section and carrying the axle at its end section
(QIC) A standard for computer tapes.
A method of obtaining a representative sample for analysis or test of an aggregate with occasional shovelsful, of which a heap or cone is formed, This is flattened out and two opposite quarter parts are rejected. Another cone is formed from the remainder which is again quartered, the process being repeated until a sample of the required size is left.
A small, roughly triangular, front-door window that swings out on fixed hinges; situated in front of and separate from the main window.
A small, roughly triangular window situated behind the main rear-door window
Quarter light filler panel
A relatively small, roughly triangular panel, usually black, inserted into the rear side-window’s rear bottom corner
The aggregation of waterlines, buttocklines, sections and diagonals indicative of a ship’s form, drawn on a scale of .25′ = 1 ft.
A supplementary device to give a third fold in line with the run of the paper on webfed presses.
A rear section of the body shell which incorporates the rear fender and usually also the C-pillar. In modern car bodies, the rear fender usually is no longer a separate welded or bolt-on panel, Instead it blends smoothly into the bottom of the rear window frame and the rear panel
Accommodations (i.e., a place where occupants of a ship can stay).
A landing extending across only half the width of a staircase.
A wreath subtending an angle of 90°
One whose overall length is approximately a quarter of free-space wavelength corresponding to frequency of operation. Under these conditions it is oscillating in its first natural mode, and is half a dipole.
Resonating two-wire or coaxial line, approximately one quarter-wavelength long, of high impedance at resonance. Used in antennas, as insulating support for another line, and as a coupling element.
Quarter-wavelength section of transmission line designed to operate as a matching device between lines of different impedance levels.
A plate of quartz, cut parallel to the optic axis, of such thickness that a retardation of a quarter of a period is produced between ordinary and extraordinary rays traveling normally through the plate. By using a quarter-wave plate, with its axis at 45° to the axes of a polarizer, circularly polarized light is obtained.
A small, roughly triangular, front-door window that swings out on fixed hinges; situated in front of and separate from the main window.
A small, roughly triangular window situated behind the main rear-door window.
A relatively small, roughly triangular panel, usually black, inserted into the rear side-window’s rear bottom corner
An algebraic equation of the fourth degree, i.e., ax4+bx3+cx2+dx+e=0. Its resolution into a pair of quadratic equations, and hence its solution, depends upon the solution of a subsidiary cubic equation.
The argument of the cumulative distribution function corresponding to a probability of either 1/4 (first or lower quartile) or 3/4 (third or upper quartile); (of a sample) the value below which occurs a quarter (first or lower quartile) or three-quarters (third or upper quartile) of the observations in the ordered set of observations.
The quarter of a sheet, or a sheet folded twice to make four leaves or eight pages; written 4to.
Crystalline silica, SiO2, occurring either in prisms capped by rhombohedra (low-temperature quartz, stable up to 573°C) or in hexagonal bipyramidal crystals (high-temperature quartz, stable above 573°C). Widely distributed in rocks of all kinds; igneous, metamorphic and sedimentary; usually colorless and transparent (rock crystal), but often colored by minute quantities of impurities as in citrine, cairngorm, etc; also finely crystalline in the several forms of chalcedony, jasper etc.
A disk or rod cut in the appropriate directions from a specimen of piezoelectric quartz, and accurately ground so that its natural resonance shall occur at a particular frequency.
A coarse-grained holo-crystalline igneous rock of intermediate composition, composed of quartz, plagioclase feldspar, hornblende and biotite, and thus intermediate in mineral composition between typical diorite and granite.
A variety of dolerite which contains interstitial quartz usually intergrown graphically with feldspar, forming patches of micropegmatite. A dyke-rock of worldwide distribution, well represented by the Whin Sill rock in N. England.
A very sensitive spring balance, the spring being a quartz fiber
A personal radiation monitor whose state can be viewed at any time. The fiber is charged periodically and discharged by radiation.
A Bulb with an inner quartz Bulb which holds a tungsten Filament. Usually the inner Bulb contains an inert gas such as iodine or one of the other five halogen gases. The use of a halogen gas prevents the Bulb from turning black and thus reducing the amount of light output. Because this type of Bulb requires intense heat, a quartz inner Bulb is needed instead of glass. As a result, the quartz-halogen Bulb produces more light per watt of electrical power. When replacing a quartz-halogen Bulb, it is important not to touch the outer Bulb with your fingers. The moisture and oils deposited on the glass will cause the glass to break under the high temperature.
A compact high-intensity light source, consisting of a bulb with a tungsten filament, filled with an inert gas containing iodine (sometimes bromine) vapor. The bulb is of quartz, glass being unable to withstand the high operating temperature (600°C). Used for vehicle-lamps, cine projectors etc.
The characteristic product of the metamorphism of a siliceous sandstone or grit. The term is also used to denote sandstones and grits which have been cemented by silica.
A type of soda-trachyte carrying accessory quartz.
One which contains a mercury arc under pressure, a powerful source of ultraviolet radiation.
One whose oscilliation frequency is controlled by a piezoelectric quartz crystal.
A porphyrite carrying quartz as an accessory constituent; the representative in the medium grain-size group of the fine-grained dacite.
A medium-grained igneous rock of granitic composition occurring normally as minor intrusions, and carrying prominent phenocrysts of quartz.
A standard of frequency comparison making use of the sharply resonant properties of a piezoelectric quartz crystal.
Quartz tuning system
(QTS) quartz-controlled tuning system with digital tuning and frequency display; uses microprocessor-controlled PLL circuitry
A thin wedge of quartz which provides a means of superposing any required thickness of quartz on a mineral section being viewed under a polarming microscope, the wedge being cut parallel to the optic axis of a prism of quartz crystal. It enables the sign of the birefringence of biaxial minerals to be determined from their interference figure in convergent light.
A form of acoustic streaming near ultrasonic transducers operated at high amplitudes
A distant, compact, object far beyond our Galaxy which looks star-like on a photograph but has a red shift characteristic of an extremely remote object.
(QBO) Alternation of easterly and westerly wind regimes in the equatorial stratosphere with an interval between successive corresponding maxima of from 24 to 30 months. A new regime starts above 30 km and propagates downward at about 1 km per month.
An astable circuit which is triggered at a high rate as compared with its natural frequency.
A circuit which operates apparently duplex, but actually functions in only one direction at a time, e.g., a long distance telephone or a radio link, which is automatically switched by speech.
A method of stress analysis for non-linear and/or time-dependent materials, especially polymers, in which elastic moduli in the elastic equations are replaced by the values of the corresponding secant modulus or creep modulus, at the required levels of strain or time, respectively.
Energy levels in a semi-conductor from which the number of electrons or holes available for conduction under nonequilibrium conditions; esp. when light is falling on the semiconductor, can be calculated in the same way as from the true Fermi level which applies under equilibrium conditions.
An approximation to the dynamical equations governing atmospheric flow, esp. the vorticity equation, whereby the horizontal wind is replaced by the geostrophic wind in the term representing the vorticity, but not in the term representing the divergence.
A special type of wave occurring in plates and bars. The particle motion is mainly longitudinal and has a small transverse component caused by lateral contraction.
Invisible electromagnetic waves with similar wavelength and laws of propagation to visible light.
A weather front which is moving slowly and irregularly so that it cannot be described as either a cold front or a warm front.
Quasi S-VHS playback
The facility for playing S-VHS tapes in a VHS video recorder – with VHS resolution.
A chemical term consisting of four components etc.; also, connected to four non-hydrogen atoms.
The geological period which succeeded the Tertiary. It includes the Pleistocene and Holocene epochs and covers a time span of approx the last two million years.
Quaternary ammonium bases
Bases derived from the hypothetical ammonium hydroxide NH4OH, in which the four hydrogen atoms attached to the nitrogen are replaced by alkyl radicals, e.g.,
(C2H5)4NOH, tetraethyl-ammonium hydroxide.
Phase diagram of four-component system.
Quaternary phaseshift keying
Used in microwave links and satellite communications to double the channel capacity of conventional binary phase-shift keying without changing the bandwidth. The phase of the carrier can be set by modulation to any one of four positions.
An Italian term for four and indicates that a car has four-wheel drive
A slate 36 x 24 in (914 x 610 mm).
A long iron or steel bolt serving in place of a timber queen-post.
A half-brick made by cutting the brick lengthwise.
The two spaced vertical ties required for roofs of more than about 30 ft (ca 10 m) span, where the central support of the tie-beam by the king-post is insufficient.
Queen post roof
A timber roof having two queen-posts but no king-post.
To damp or suppress a spark.
A resistor or resistor-capacitor shunting a contact, to reduce high-frequency sparking when a current is broken in an inductive circuit
A material introduced into a luminescent substance to reduce the duration of phosphorescence.
The lower frequency signal used to quench intermittently a high-frequency oscillator, e.g., in a super-regenerative receiver.
Hardening a ferrous alloy by austenitizing and then cooling rapidly enough so that some or all of the austenite transforms to martensite
Dipping a heated object into water, oil or other substance, to quickly reduce the temperature. Quenching into water gives a more rapid cooling rate than into oil. The term also applies to cooling in salt and molten-metal baths or by means of an air blast. Applied to steels heated above their upper critical temperature in order to harden them prior to tempering and to other alloys for solution treatment prior to precipitation hardening.
A nuclear engineering term to describe the process of inhibiting continuous discharge, by choice of gas and/or external valve circuit, so that discharge can occur again on the incidence of a further photon or particle in a counting tube.
A suppression of oscillation, particularly periodically, as in a super-regenerative receiver.
Rapid cooling. When applicable, the following more specific terms should be used: direct quenching, fog quenching, hot quenching, interrupted quenching, selective quenching, spray quenching, and time quenching.
One with a frequency slightly above the audible limit, and which generates the voltage necessary to quench the high-frequency oscillations in a super-regenerative receiver.
Oil injected into the product stream leaving a cracking or reforming heater. It lowers the temperature of the stream and thus stops (quenches) any further, undesired, chemical reaction.
That required to quench the discharge of a Geiger tube. dead time for internal quenching, paralysis time for electronic quenching, although dead time is often used synonymously for the other two terms.
Those areas within the combustion chamber of an engine where the temperature of the air-fuel mixture is lower than necessary for optimum combustion, due to contact with the relatively cold metal surface; incomplete combustion in the quench zones is one of the two major factors contributing to HC and CO concentrations in the exhaust gas
A method of retrieving information interactively from a database without having to write a complex program. Simple commands such as FIND postcode = ‘SO9 2QU’ are used.
A list for which insertions are made at one end and deletions at the other. The arrangement is called FIFO.
Programs waiting, in order determined by their priority, for access to the central processor in a time-sharing system.
The situation that arises in a digital network or other system when data arrives at a device faster than the device can process it, in which data is allowed to accumulate in a buffer until a reduction in data rate allows it to be dealt with.
A switch having a spring or other device to produce a quick break, independently of the operator.
A device which permits easy and fast connecting of two fluid lines.
Electrodeposition of mercury on a surface before regular plating.
A special bicycle chain connecting link that allows derailleur-type chains to be disassembled and reassembled without the use of tools
Quick make-and-break switch
An electrical switch which makes and breaks the circuit with a quick snap.
The minimum input signal required by a frequency-modulation radio receiver to give a specified signal/noise ratio at the output.
Similar to the Rattrap type of bicycle pedal except that the two sides of the pedal frame are joined by a piece of metal that loops around the Dust cap.
A form of drive used for electric locomotives in which the armature of the driving motor is mounted on a quill surrounding the driving axle, but connected to it only by a flexible connection. This enables a small amount of relative motion to take place between the motor and the driving axle.
A hollow non-rotating shaft in which another shaft rotates under power, for providing axial movement as in a drilling machine spindle.
2-methylquinaline. C10H9N. Bp 246°C. A colorless refractive liquid, which occurs to the extent of 25% in quinoline obtained from coaltar.
A method for determining the magnetic susceptibility of a substance in solution by measuring the force acting on it in terms of the change of height of the free surface of the solution when placed in a suitable magnetic field.
C6H4O2 + C6H4(OH)2. An additive compound of one molecule of l.4 quinone and one molecule of l.4-dihydroxybenzene. It crystallizes in green prisms with a metallic luster.
A system consisting of a clean, polished, gold or platinum electrode dipping into a solution containing a little quinhydrone, for determining pH-values, making use of the pH dependence of the redox properties of the system
C20H24O2N2N23H2O. Mp 177°C. An alkaloid of the quinoline group, present in Cinchona bark. It is a diacid base of very bitter taste and alkaline reaction. It crystallizes in prisms or silky needles; the hydrochloride and sulfate are used as a febrifuge but have been largely superseded as a remedy for malaria, although they are still used in the treatment of leg cramps.
A synonym for 1.4-dihydroxy-anthra-quinone
A heterocyclic compound consisting of a benzene ring condensed with a pyridine ring. It is a colorless, oily liquid, mp -19.5°C, bp 240°C, rel.d. 1.08, of characteristic odor, insoluble in water, soluble in most organic solvents. It is found in coaltar, in bone oil, and in the products of the destructive distillation of many alkaloids. It can be synthesized by heating a mixture of aniline, glycerine, and nitrobenzene with concentrated sulfuric acid.
Compounds derived from benzene and its homologues by the replacement of two atoms of hydrogen with two atoms of oxygen, and characterized by their yellow color and by being readily reduced to dihydric phenols. According to their configuration they are divided into 1.2-quinones and 1.4-quinones.
A formula based upon the diketone configuration of 1.4-quinone (benzoquinone), involving the rearrangement of the double bonds in a benzene nucleus; adopted to explain the formation of dyestuffs, e.g., colored salts of compounds of the triphenylmethane series.
A group of heterocyclic compounds consisting of a benzene ring condensed with a diazine ring. They can be obtained by the condensation of 1.2-diamines with 1.2-diketones.
(q) Unit of mass in the metric system, equal to 100 kg.
An algebraic equation of the fifth degree. Unlike like equations of lower degree, its general solution (and that of equations of higher degree) cannot be expressed in terms of a finite number of root extractions.
(PCNB) Pentachloronitrobenzene. Used as a fungicide
A point on a concentration-pressure-temperature diagram at which a three-component system can exist in five phases.
A paper quantity 25 sheets or 1/20 of a ream
On a rotary printing press, as the product is delivered, it is separated into quires or batches by the kicker which delivers a kick copy at the required interval.
Sections which after printing are folded and insetted one in the other. This method allows the booklet to be stitched instead of stabbed.
The narrow groove alongside a bead sunk flush with a surface.
A plasterer’s trowel specially shaped for finishing moldings.
A molding having a small groove in it
A form of plane for shaping quirks
A deed of relinquishment of a claim or portion of mining ground.
An exterior angle of a building, esp. one formed of large squared cornerstones projecting beyond the general faces of the meeting wall surfaces.
A wooden wedge or a metal device used to lock up forms.
A brick laid at the external angle of a building to be a header in the wall proper and a stretcher in the return wall.
Metal spaces of varying widths, 1, 2, 3, or 4 em used for filling blanks in pages or forms.
The group G/N whose elements are the cosets of N in G, where N is a normal subgroup of G. The product of two cosets is defined to be equal to the coset which contains the product of an element of the first coset and an element of the second.
Quantity of energy released in a given nuclear reaction. Normally expressed in MeV, but occasionally in atomic mass units.
Ratio of thermonuclear power output to power needed to maintain the plasma.
A keyboard laid out in the standard typewriter pattern where the top row of letters begins with the letters QWERTY