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 DiracDelta - Science & Engineering encyclopedia
Category: Sciences > Science & Engineering
Date & country: 01/12/2007, UK
Words: 4470


Transistor
Term derived from 'transfer resistor.' Semiconductor device that can be used as an amplifier or as an electronic switch.A three leaded device (Collector, Base, Emitter) used for amplifying or switching. Also called a bi-polar transistor to distinguish it from Field Effect Transistor etc.An active semiconductor device that operates like a current va…

Transistor-Transistor Logic (TTL)
Referring to logic circuits consisting of two or more directly interconnected transistors, to provide conditional switching capability.

Transition Metal
An element with an incomplete d subshell. Elements which have common cations with incomplete d subshells are also considered transition metals. Elements with incomplete f subshells are sometimes called 'inner transition elements'.HHeLiBeBCNOFNeNaMgAlSiPSClArKCaScTiVCrMnFeCoNiCuZnGaGeAsSeBrKrRbSrYZrNbMoTcRuRhPdAgCdInSnSbTeIXeCsBaLaHfTaWReOsIrPtAuHgT…

Transitive
Describes the property that if the relation holds between a first object and a second, and between the second and a third, then it holds between the first and the third. For example, is greater than is transitive, if a>b and b>c then a>c.

Translational
Motion through space as opposed to rotation. See also: Isometry.

Transmissibility
The nondimensional ratio of the response amplitude of a system in steady-state forced vibration to the excitation amplitude. The ratio may be one of forces, displacements, velocities, or accelerations.

Transmission Electron Microscope
A microscope that produces an image by using electron beams to pass through the specimen, making examination of internal features at high magnifications possible.

Transmission Error
This is the difference between the actual position of the output gear and the position it would occupy if the gear drive were perfect. This is usually expressed as angular displacement and may be shown as linear displacement at the pitch point. Transmission error is the primary excitation of gear noise and is dependent on load. See also: Gear Desig…

Transmission Line
A structure that guides electromagnetic energy. See also: Load, Mayer Method.

Transmutation
A process of converting one element to another by irradiating or bombarding it with radioactive particles.

Transonic
A range of speed between about 0.8 and 1.2 times the speed of sound in air.

Transuranic
Transuranic is a chemical term referring to artificially manufactured elements which have an atomic number higher than uranium. See also: Uranium.

Transverse Wave
A wave in which the vibrations of the medium are perpendicular to thedirection the wave is moving.

Treble
The higher frequencies of the audible spectrum. See also: Audio Frequency, Bass.

Triac
Similar to a thyristor but allows current to flow in both directions. See also: Thyristor.

Triad
A unit of quantity equal to three. See also: Triple.

Triangle
Law of SinesLaw of CosinesLaw of TangentsAlso,where

Triangulation
In general, the unique location of the source from some combination of at least three ranges and/or bearings in three dimensional space. See also: Tomography, Trilateration.

Tribology
The technology of interacting surfaces in relative motion and concerned with the design, friction, lubrication, and wear of contacting surfaces that move relative to one another.

Trichlorethene
A solvent and dry cleaning fluid. Symbol C2HCl3

Trichlorofluoromethane
A colourless, nearly odorless liquid that boils at about room temperature. This was the first widely used refrigerant. Symbol CCl3F Also known as Freon-11, Fluorotrichloromethane

Tridecagon
A 13 sided polygon. See also: Polygon.

Trilateration
Method of surveying wherein the lengths of the triangle sides are measured, usually by electronic methods, and the angles are computed from the measured lengths. See also: Triangulation.

Trillion
A number equal to 1012. See also: Billion, Quadrillion.

Trinitrotoluene
Used as a high explosive and known as TNT.

Triode
A triode is an electronic amplifying valve with three main electrodes (anode, cathode and grid). See also: Valve.

Trioxide
In chemistry, a trioxide is a compound with three atoms of oxygen with an element or radical.

Triplane
A fixed wing aeroplane with 3 wings arranged one above the other. See also: Biplane, Monoplane.

Triple
A group of three items. See also: Quartet, Sextuple, Triad.

Triple Point
The temperature at which solid, liquid and vapour can exist together in equilibrium. For water this temperature is 273.16K.Click on an item to paste into clipboard or use clipboard symbol at end to clipboard all values Benzoic Acid 395.52 KClip Hydrogen Equilibrium 13.81 Normal 13.956 KClip Neon 24.555 KClip Nitrogen 63.148 KClip Oxygen 54.361 KCli…

Trisect
To cut an object into three equal parts. See also: Bisect.

Tritium
A radioisotope of hydrogen with two neutrons and one proton in its nucleus. It is radioactive to beta decay with a half life of 12.5 years. In a nuclear fusion device, lithium is important as a source of tritium and serves as a booster for the fusion reaction in the secondary component of a nuclear weapon.

Triton
Nucleus of a tritium atom. See also: Tritium.

Tropism
The movement of a plant in response to a stimulus.ChemotropismMovement in response to chemicals.GeotropismMovement in response to gravity.Negative Geotropism - shoots grow upwards.Positive Geotropism - roots grow downwards.HaptotropismResponse to touch such as tendrils on a climbing plant wrapping themselves around other plants or supports.Hydrotro…

Tropospheric Ducting
Tropospheric ducting is the propagation of radio signals above 30Mhz via bending and ducting along weather fronts in the lowest layer of the Earth's atmosphere, the troposphere.

Trough
A valley of a wave disturbance. See also: Crest, Peak to Peak Value, Wave.

Trowel
A handtool with a flat sheet steel surface that is rectangular or pointed and is used to manipulate and finish concrete or plaster.Brick Jointer TrowelPhotograph courtesy of Draper.co.ukUsed to create the finished mortar surface of a brick joint.Brick TrowelPhotograph courtesy of Draper.co.ukUsed by a bricklayer to place mortar between bricks.Plast…

Troy Ounce
An old British unit of mass mainly used for measuring prescious metals. 1 troy ounce = 31.1035 gConversions1 troy ounce=31.1035 g1 troy ounce=480 grainttle='Mass';xiunt='troy ounce';yiunt='kg';mconv=32.150743260882706;cconv=0.0; See also: Mass.

True Strain
The ratio of the change in dimension, resulting from a given load, to the magnitude of the dimension immediately prior to applying the load. The natural logarithm of the ratio of the gauge length at the moment of observation to the original gauge length. See also: Strain.

True Stress
The load applied to a material divided by the cross sectional area over which it acts. See also: Stress.

Truth Table
A tabular representation of a logic gate showing all the possible combinations. AND Gate

Tsunami
A giant wave set in motion by a large earthquake under or near the ocean that causes the ocean floor to shift vertically.These waves may reach enormous dimensions and have sufficient energy to travel across entire oceans. They proceed as ordinary gravity waves with a period between 15 and 60 minutes. Tsunamis steepen and increase in height on appro…

Tungsten
Tungsten metal is lustrous and silvery white in colour, and does not occur naturally (it has an abundance of 1 ppm in the earth`s crust). It is found in the ore Wolframite, a tungstate of iron and manganese, (FeMn)WO4, which is converted to the trioxide and then reduced to the metal by reduction in hydrogen (carbon cannot be used as the …

Tungsten Carbide
Strong alloy often used in grinding and polishing.

Tuning Fork
Tuningfork photograph courtesy of Indigo® Instruments.A small two-pronged steel instrument which when struck produces a fixed tone.

Tunnel Diode
Heavily doped junction diode that has negative resistance in the forward direction of its operating range. See also: Diode.

Turbine
A rotary machine which extracts mechanical shaft power from the working fluid, gas or liquid, using rotor vanes. Steam turbines often propel ships and power stations. Gas turbines are also used.

Turbocharger
A supercharger powered by an exhaust-driven turbine. Turbochargers always use centrifugal-flow compressors, which operate efficiently at the high rotational speeds produced by the exhaust turbine.Boost PressureThe increase above atmospheric pressure produced inside the intake manifold by a forced-induction system such as a turbocharger or superchar…

Turbulence
Describes fluid motion disturbed from its average behaviour by random fluctuations over a range of temporal and spatial scales. See also: Aerodynamic Noise.

Turnbull's Blue
Turnbull's Blue is a pigment produced by the action of a ferrous salt on potassium ferri-cyanide.

Turpentine
Distilled pine oil, used as a cleaner, solvent or thinner for oil-based and alkyd coatings.

Twin
Two portions of a crystal with a definite orientation relationship; the orientation of one portion is a mirror image of the orientation of the other portion across a twinning plane or an orientation derived by rotating one portion about a twinning axis. See also: Crystal.

Twin Primes
Two prime numbers that differ by 2. eg 11 and 13. See also: Prime Numbers.

Twist Drill
A commonly used metal-cutting drill, usually made with two flutes running around the body. See also: Drill Bits.

Twisted Pair
Cable that consists of individual wires wrapped around each other for carrying telephone or computer data. Reduces pickup noise levels in signals. See also: Noise.

Two-Stroke Engine
An internal-combustion engine that has one power stroke per revolution.

Tyndall Effect
Light passing through a colloid is scattered by suspended particles. The light beam becomes clearly visible; this phenomenon is called the Tyndall effect. Examplecar headlight beams can be seen in fog, but the beams are invisible in clear air.

Tyndall, John (1820-93)
Tyndall is tagged as an English physicist, lecturer and writer. He collaborated with T. H. Huxley in certain of his scientific studies. A classic, is Tyndall's book, Fragments of Science. In addition, Tyndall wrote Six Lectures on Light (London: Longmans, Green; 1885). Studied the diffusion of light by large molecules and dust, known as the Tyndall…

Typematic Rate Delay
In computer terms, the typematic rate delay is the initial delay before key auto-repeat starts. That is how long you've got to press a key before it starts repeating. See also: Typematic Rate.

Typematic Rate
In computer terms, the typematic rate is how fast keys repeat when held down. See also: Typematic Rate Delay.

Tyre
The rubber part of the wheel which contacts the ground. The construction can be bias-ply, bias-belted, or radial. The plies are made of rayon, nylon, and polyester. Belting can be fibreglass, steel, or kevlar. The rest of the tyre is hard rubber.Tyre BeadThat portion of the tire that bears against the rim flange. The bead has a number of turns of s…

Tyrian Dye
Tyrian dye was a purple dye derived from animal juice in the shell-fish murex. It was used in ancient times. Since only small quantities could be obtained, it's use was limited to the great and the wealthy, hence purple became the colour associated with majesty.

Ultimate Strength
Maximum stress at point of rupture. See also: Working Stress.

Ultra High Frequency
Radio frequencies that are between 300 to 3000 MHz. See also: Super High Frequency, Very High Frequency.

Ultramarine
Ultramarine is a blue pigment derived from lapis lazuli.

Ultrasonic
Sound at frequencies above the audible range, i.e. above about 20 kHz.Biological effects of ultrasound:Thermal â€` tissue is damaged due to heatingNonthermal â€` tissue damage due to mechanisms other than heating. These include mechanical forces on or within the tissue.Cavitational mechanisms â€` microstreaming, shock waves and microjetsNon-cavitational …

Ultrasonic Cleaning
An effective cleaning process for small items and fine detail where the item is immersed in a bath of cleaning fluid that is excited at ultrasonic frequenices (i.e. greater than 20kHz).

Ultrasonic Testing
A method of non destructive testing of steel bars, plates or parts with high frequency sound waves produced with electronic equipment. The test is used for locating internal or surface discontinuities or inhomogeneities in materials. See also: Ultrasonic.

Ultraviolet Light
Electromagnetic radiation with wavelength longer thanthat of x-rays but shorter than that of visible light, wavelengths range from 1x10-9m to 400x10-9m. Ultraviolet light canbreak some chemical bonds and cause cell damage.Used for exposing photoresist in making semiconductor devices.

Umber
Umber is a substance comprised of hydrated ferric and manganese oxides with variable proportions of earthy matter. It is used as a brown pigment.

Umbra
The darkest part of a shadow where no light from the source reaches.

UNC
SizeTapping Drill mmPitch mmTPIOD mm2-56 UNC1.850.45562.183-48 UNC2.100.53482.514-40 UNC2.350.64402.846-32 UNC2.840.79323.518-32 UNC3.500.79324.1710-24 UNC3.901.06244.8312-24 UNC4.551.06245.491/4-20 UNC5.301.27206.355/16-18 UNC6.601.41187.943/8-16 UNC8.001.59169.537/16-14 UNC9.401.811411.111/2-13 UNC10.801.951312.709/16-12 UNC12.252.121214.295/8-11…

Undecagon
An eleven sided polygon. Each internal angle is 147.3° and the sum of the internal angles is 1620°. See also: Polygon.

Under-Cooling
Cooling a material below the temperature of an equilibrium phase change fast enough to not allow the occurrence of the transformation.

Understeer
A handling condition in which the slip angle of the front tyres is greater than the slip angle of the rears. An understeering car is sometimes said to push, because it resists turning and tends to go straight.

UNF
SizeTapping Drill mmPitch mmTPIOD mm2-64 UNF1.900.40642.183-56 UNF2.150.45562.514-48 UNF2.400.53482.846-40 UNF2.950.64403.518-36 UNF3.550.71364.1710-32 UNF4.100.79324.8312-28 UNF4.650.91285.491/4-28 UNF5.500.91286.355/16-24 UNF6.901.06247.943/8-24 UNF8.501.06249.537/16-20 UNF9.901.272011.111/2-20 UNF11.401.272012.709/16-18 UNF12.901.411814.295/8-18…

Unicode
Unicode is a standard of computer character sets that aims to unambiguously represent every known glyph in every human language. Unicode's native encoding is 32 bit (older versions use 16 bits). See also: American Standard Code for Information Interchange.

Uniform Motion
Motion at a constant velocity.

Uninterruptible Power Supply
A type of power supply designed to support the load for specified periods when the line varies outside specified limits.

Unit
A standard for comparison in measurements. For example, the metre is a standard length which may be compared to any object to describe its length. See also: Conversions, Engineering Units, SI Units, Unit Cube.

Unit Cell
The smallest repetitive volume that comprises the complete pattern of a crystal. See also: Atomic Packing Factor, Crystal.

Unit Circle
A circle with radius 1.

Unit Cube
A cube with edge length 1. See also: Cube, Unit.

Unit Fraction
A fraction whose numerator is 1. See also: Fraction.

Unit of Blood
Unit of volume for human blood and its components. A unit of whole blood is 450 millilitres. For components of blood, one unit is the amount of that substance that would normally be found in one unit of whole blood.The adult human body contains roughly 12 units of whole blood.ttle='Unit of Blood';xiunt='litre';yiunt='unit of blood';mconv=0.45;cconv…

Unit Square
A square of side length 1. See also: Square.

Unit Vector
A vector with a length of 1.

Unity
One.

Universal Indicator
A universal indicator is an indicator which undergoes several colour changes over a wide range of pH. The colour is used to 'indicate' pH directly. Universal indicators are usually mixtures of several indicators. See also: pH.

Universe
All the matter and space that exists.Age of the UniverseThe time elapsed since the singularity predicted by the Big Bang theory, estimated to be around 13 billion years.

Unnilhexium
Element with an atomic number of 106. Symbol Unh

Unnilpentium
Element with an atomic number of 105. Symbol Unp

Unnilquadium
An element with an atomic number of 104. Symbol Unq

Unnilseptium
An element with an atomic number of 107. Symbol Uns

Unsaturated Compounds
In chemistry, unsaturated compounds are organic compounds containing double or triple bonds and are capable of forming addition products.

Unsaturated Solution
A solution with a concentration lower than its equilibrium solubility. See also: Concentration.

Unsigned Binary Number
A binary number in which all the bits are used to represent positive quantities. Thus, an unsigned binary number can only be used to represent positive values.function init(){}This will convert decimal numbers up to 255 and binary up to 11111111 multicalc_form(0)

Uranium
Although uranium is the longest known member of the actinide group of metals, it attracted scant attention until the discovery of uranium fission in 1939. It is now of vital importance as a nuclear fuel. Uranium occurs naturally as two main isotopes, 238U (99.3%) and 235U (0.7%), along with a trace of a third isotope, 233…

Uranium Oxide
Greyish-black brittle and heavy mineral. Uraninite is the name given to naturally occuring Uranium Oxide. Symbol UO2

Uranus
The seventh planet from the sun in our solar system.Click on an item to paste into clipboard or use clipboard symbol at end to clipboard all values Equatorial diameter 51118000 mClip Average Density 1270 kgm-3Clip Axial tilt 97.9 degreesClip Rotational period 17.23 hoursClip Average surface temperature -210 °CClip Maximum apparent magnit…