Copy of `DiracDelta - Science & Engineering encyclopedia`

The wordlist doesn't exist anymore, or, the website doesn't exist anymore. On this page you can find a copy of the original information. The information may have been taken offline because it is outdated.

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

Subwoofer
A speaker designed exclusively for low-frequency reproduction. See also: Loudspeaker.

Sugars
Sugars are a group of carbohydrates, soluble in water and having a sweet taste. The group includes glucose, lactose and saccharose. Sugars are classified as monosaccharides, disaccharides, or trisaccharides. See also: Carbohydrate.

Sulphur
Photograph courtesy of MineraliteSulphur is a non-metallic element occurring in several allotropic forms. Symbol S

Sulphur Dioxide
A colourless gas formed when sulphur is burnt in air and forms sulphurous acid when dissolved in water. Symbol SO₂

Sulphuric Acid
An oily, corrosive liquid that acts as a strong acid when dissolved in water. Sulphuric acid has so many industrial uses that sulfuric acid production was once used as an index of industrial productivity. Salts of sulphuric acids are called sulphates. Symbol H₂SO₄ Also known as Oil of Vitriol

Sulphurous Acid
A colourless liquid that acts as a weak acid when dissolved in water, sometimes used as a bleach. Salts of sulphurous acid are called sulphites. Symbol H₂SO₃

Sun
The star at the centre of our solar system. In the sun, the basic fusion process converts hydrogen to helium liberating large amounts of energy. The sun converts about 2 million kg of mass to energy every second.Equatorial radius6.96x10⁸mMass1.9891x10³⁰kgPolar moment of inertia5.7x10⁴⁶kgm²Bolometric lumin…

Sun Protection Factor
A rating for lotions used to protect the skin against sunburn. Abbreviated as SPF. An SPF 10 would mean that anybody who would be burnt in 12 minutes without any protection would be able to last 120 minutes with this level of sun lotion.

Sundial
A device for telling time of day by the shadow which sunlight produces on the instrument.GnomonThe part of a sundial which casts the shadow, usually a rod or fin pointed at the celestial pole.

Super High Frequency
Radio Frequencies between 3 GHz and 30 GHz See also: Ultra High Frequency, Very High Frequency.

Supercharger
An air compressor used to force more air into an engine than it can inhale on its own. The term is frequently applied only to mechanically driven compressors, but it actually encompasses all varieties of compressors-including turbochargers. Including:RootsLysholmCentrifugalCrankcase

Supercluster
A cluster of clusters of galaxies which stretches for hundreds of millions of light years. So far about fifty have been observationally identified. See also: Galaxy.

Supercomputer
A general term used to describe the fastest available mainframe computers. See also: Computer.

Superconductivity
The phenomena by which, at sufficiently low temperatures, a conductor can conduct charge with zero resistance. The current theory for explaining superconductivity is the BCS theory. Named after J. Bardeen, L.N. Cooper and J.R. Schrieffer.A theory put forth to explain both superconductivity and superfluidity. It suggests that in the superconducting …

Supercooled
Liquids at temperatures below their normal freezing points are said to be 'supercooled'.

Supercritical
A chain reaction that grows rapidly because an average of more than one neutron from each fission reaction causes another fission reaction. An extreme example of this is the explosion of a nuclear bomb. See also: Neutron, Subcritical.

Superficial Rockwell Hardness Test
Form of Rockwell hardness test using relatively light loads which produceminimum penetration. Used for determining surface hardness or hardness of thin sections or small parts, or wherelarge hardness impression might be harmful. See also: Knoop Hardness Test, Rockwell Hardness.

Superfluidity
The phenomena by which, at sufficiently low temperatures, a fluid can flow with zero viscosity. Its causes are associated with superconductivity. See also: Viscosity.

Supergiant
A star with a higher luminosity and a larger radius than a giant of the same spectral classification. It will have typically one hundred times the luminosity of a giant. It will almost certainly become a supernova. Blue SupergiantA supergiant star with spectral type O or B. Red SupergiantA supergiant with spectral type M. These are the largest star…

Supernova
The death explosion of a massive star, resulting in a sharp increase in brightness followed by a gradual fading. At peak light output, supernova explosions can outshine a galaxy. The outer layers of the exploding star are blasted out in a radioactive cloud. This expanding cloud, visible long after the initial explosion fades from view, forms a supe…

Superposition
The general idea that, when a number of influences are acting on a system, the total influence on that system is merely the sum of the individual influences; that is, influences governed by the superposition principle add linearly. Some specific examples are:Superposition Principle of Forces The net force on a body is equal to the sum of the forces…

Supersonic
Having a speed greater than the speed of sound in a given medium, especially air. See also: Hypersonic, Hypervelocity, Mach Number, Sound, Subsonic.

Supplementary Angles
Two angles are supplementary if they add up to 180°. See also: Angles.

Support
A support contributes to keeping a structure in place by restraining one or more degrees of freedom. In a structural model, supports represent boundary entities which are not included in the model itself, e.g., foundations, abutments, or the earth itself. For each restrained translation degree of freedom at a support, there is a corresponding react…

Surd
Used in mathematics to describe an irrational quantity. See also: Irrational Number.

Surface Combustion
Surface combustion is a method of causing a mixture of air and gas to burn by bringing it into contact with a suitable porous surface. Usually this consists of a diaphragm of porous refractory material, to one side of which a mixture of gas and air is supplied under a low pressure.

Surface Force
A force applied to the surface of an object. See also: Body Force, Concentrated Force, External Force, Force.

Surface Gauge
Photograph courtesy of Draper.co.ukA gauge used to check the accuracy, of plane surfaces, to scribe lines at desired distances from a given surface and to check the height of a point or points on a piece of work from a given surface.

Surface Mount Technology
The technology used when components are mounted to the surface of circuit boards. Surface mount technology allows smaller component size, improves signal speed, increases reliability and automation in manufacturing, and requires less handling of parts.

Surface Roughness
At a microscopic scale, no surface appears perfectly smooth.

Surface Tension
The work required to expand the surface of a liquid by unit area.The surface behaves as if it were covered with an elastic stretched skin. The effect is due to the fact that at the surface the attraction between the molecules of the liquid is unbalanced, surface molecules being attracted towards the body of the liquid, whereas in the body of the li…

Surfactant
A material that spreads along a surface, changing the properties of the surface.An example is soap.Soap spreads over a water surface and lowers its surface tension.

Surge Protector
A device for protecting electronic equipment from damaging voltage levels sometimes occurring in electrical transients. See also: Volt.

Suspension
ChemistryA system consisting of small particles dispersed in a liquid. The particles will settle out slowly upon standing.

Swing By
A particular manoeuvre that exploits the gravitational force of a moon or a planet to modify the trajectory of a spacecraft and to boost it into space.

Switch
Mechanical switches are used to permit or interrupt the flow of current in a circuit. They can be used to direct current to different points in a circuit.

Switching Time
The time required for the output of a switch to attain 90 percent of its steady-state level referenced to the 50 percent level of the command signal.

Symbol ic Logic
A mathematical form in which propositions and their relationships may be represented symbolically using Boolean equations, truth tables, Karnaugh maps, or similar techniques.

Synaesthesia
A 'cross talk' effect in the brain in which one sensory pathway links across to another, resulting in two outputs from one input.The commonest form of synaesthesia is the linking of colours to printed letters and numbers. The letters may appear to be coloured even though they are printed as black. Other effects are to 'see' music in colours. It is …

Synchronous
ElectronicsThe transmission of data between a transmitting and receiving device occurs as a series of zeros and ones. For the data to be 'read' correctly, the receiving device must begin reading at the proper point in the series. In synchronous communication, this coordination is accomplished by synchronizing the transmitting and receiving devices …

Synchronous Averaging
A type of signal averaging where successive records of the time waveform are averaged together. This is also know as time domain averaging. The important criterion is that the start of each time record must be triggered from a repetitive event in the signal, such as 1X rpm. The triggering assures that the phase of the waveform components that are s…

Synchrotron
A type of circular accelerator in which the particles travel in synchronized bunches at fixed radius. See also: Accelerator, Collider, Synchrotron Radiation.

Synchrotron Radiation
Electromagnetic radiation emitted by a very high-energy electron, moving in a magnetic field. See also: Synchrotron.

Syneresis
The shrinking of a gel, with the expulsion of water or other liquid from it.

Synthesis
ChemistryThe construction of a compound by the union of elements or simple compounds.

Systematic Error
A measurement error in an instrumentation system which is predictable and correctable.

Tablespoon
A convenient unit of capacity.Conversions1 tablespoon (UK)=14.20653x10^-6m³1 tablespoon (US)=14.78676x10^-6m³ttle='tablespoon';xiunt='m³';yiunt='tablespoon (UK)';mconv=14.20653e-6;cconv=0.0; See also: Fluid Ounce, Teaspoon, Volume.

Tachyon
A tachyon is a theoretical particle that always travels faster than light. See also: Velocity of Light in Vacuo.

Tandem Mill
Arrangement of rolling mills, in direct line, allowing the metal to pass from one set of rolls to the next for the reduction of steel. See also: Mill.

Tang
The flat on the shank of a cutting tool, such as a drill, reamer or end mill, that fits a slot in -the spindle of a machine to keep the tool from slipping. See also: Drill Bits.

Tangent
A line that meets a smooth curve at a single point and does not cut across the curve.OrA trigonometric function. The trigonometric function of angle A is defined as:

Tangential Mode
A room mode produced by reflections off four of the six surfaces of the room. See also: Room Modes.

Tantalum
Tantalum is a shiny, silvery coloured metal which is heavy, dense, malleable and ductile when pure. It is found in small quantities in minerals (generally in conjunction with niobium), and is isolated by conversion to the oxide and then the fluoro-complex, K2 TaF7 , from which the pure metal is obtained by electrolysis. Tantalum is extremely corros…

Tap Wrench
A bar with a hole and clamping device or T-bar design to hold a tap used to make internal threads.

Tape
A strip of long, thin, narrow material that may be rolled up.

Taper Roller Bearing
A bearing composing of a cone of rollers and a matching cup for the rollers to sit within. See also: Bearing.

Tappet
A tappet is an arm, collar or cam within a machine which imparts intermittent motion.

Tar
A mixture of hydrocarbon oils.

Target Population
The entire group a researcher is interested in, the group about which the researcher wishes to draw conclusions. See also: Population.

Taste
Four basic tastes are sour, sweet, salt and bitter.

Tau
The third flavor of charged lepton (in order of increasing mass), with electriccharge -1.Click on an item to paste into clipboard or use clipboard symbol at end to clipboard all values tau mass 3.16788e-27 kgClip tau-electron mass ratio 3477.60 Clip tau-muon mass ratio 16.8188 Clip tau-proton mass ratio 1.89396 Clip tau-neutron mass ratio 1.89135 C…

Tautomer
A structure formed by facile motion of a hydrogen from one site to another within the same molecule. See also: Hydrogen.

Teak
A strong and durable wood that doesn't shrink much and is comparatively easy to work. Valuable for many purposes on account of the small amount of shrinkage which takes place with seasoning.

Teaspoon
A convenient unit of capacity.Conversions1 teaspoon (UK)=4.735513x10^-6m³3 teaspoon (US)=4.928922x10^-6m³ttle='teaspoon';xiunt='m³';yiunt='teaspoon (UK)';mconv=4.735513e-6;cconv=0.0; See also: Fluid Ounce, Tablespoon, Volume.

Technetium
A radioactive element not found in ores. Symbol Tc

Tectonic Earthquakes
Earthquakes resulting from sudden release of energy stored by major deformation of the Earth.

Tee Joint
A joint between two members located approximately at right angles to each other in the form of a T. See also: Joint.

Telescope
Instrument used to focus electromagnetic radiation (light, X-rays) into an image. See also: Cassegrain Telescope, Reflecting Telescope, Refracting Telescope.

Telescoping Gauge
A T-shaped gage used to measure the diameter or width of holes.

Tellurium
Tellurium is a rare, silvery-white, semi-metallic element which exhibits both metallic and non-metallic traits and has an abundance of 0.005 ppm in the earth`s crust. It exists in only one form, whereas the other members of the oxygen group of elements in the periodic table all exhibit at least two allotropic forms. It is generally found in combina…

Telodynamic Transmission
The system of transmitting power over long distances by means of pulleys and wire ropes. See also: Pulley.

Temper
The state of or condition of a metal as to its hardness or toughness produced by either thermal or heat treatment and quench or cold working or a combination of same in order to bring the metal to its specified consistency. In heat treatment, reheating hardened steel or hardened cast iron to some temperature below theeutectoid temperature for the p…

Temper Colours
The colours which appear on the surface of steel heated at low temperature in an oxidizing atmosphere. See also: Colour Temperature, Temper.

Temperature
A measure as to whether two bodies are hot or cold relative to one another. It determines the direction of spontaneous heat flow, always from hot to cold.function init(){function init(){}init();}Enter one value and then press calculate.multicalc_form(0)

Temperature Range
The minimum to maximum temperature over which a piece of equipment will operate. See also: Temperature.

Tempering
Reheating a quench-hardened or normalized ferrous alloy to a temperature below the transformationrange and then cooling at any rate desired. See also: Quenching.

Tempo
The speed of occurrence of the beats for a given metric structure. In a musical score, the tempo is specified in terms of the number of metric units per minute, for example, quarter-note = 60, in which the time value of each quarter-note is 1 second. The inverse of tempo, the time between beats, is called the beat period.

Temporal
An adjective meaning 'pertaining to time'.

Temporary Threshold Shift
A temporary impairment of hearing acuity as indicated by a change in the threshold of audibility.Sustained exposure to moderately high noise levels over a period of time can cause gradual hearing loss. It starts out as a temporary hearing loss, such as immediately after a loud rock concert. The hearing usually restores itself within a few hours aft…

Tensile Strength
The ultimate strength of a material prior to fracture when subjected to an increasing tension load.For brittle solids: ceramics, glasses and brittle polymers - it is much less than the compressive elastic limit. For metals, ductile polymers and most composites - it is larger than the yield strength by a factor ranging from 1.1 to 3.Click on an item…

Tensile Stress
Stress acting on the cross-sectional area of a body normal to the tension force acting on the body. See also: Bending Stress, Compressive Stress, Neutral Plane, Shear Stress, Stress.

Teratogen
A substance that can cause deformities in embryos. Dioxin is a teratogen.

Terbium
A lanthanide group metal, it is soft, malleable and ductile. Terbium has an abundance of 1.1 ppm in the earth`s crust and is found in minerals in combination with other lanthanide group elements. It is slowly oxidised in air, the rate of the reaction being increased if terbium powder is used. Terbium reacts slowly with cold water. Terbium is used i…

Terminal
ChemistryThe end of a polymer molecule.ElectronicsA point at which electrical connections can easily be made or broken.

Terminal Reaction
A reaction that ends a cycle or chain of other chemical reactions. See also: Reaction.

Terminal Speed
The speed obtained in free fall when the upward force of air resistance is equal to the downward force of gravity.Balancing the force due to air resistance, F_A and the downward force of gravity, F_gthis givesthis can then be rearranged to give the terminal speed, vwhereF = aerodynamic drag force [N]C_d = drag coeffici…

Termination Shock
Where particles from the Sun begin to slow and clash with matter from the sparse gas found between the stars. At this point the solar wind slows abruptly from a speed in the range 1.1-2.4 million km/h and becomes denser and hotter. Changes in the speed and pressure of the solar wind cause the termination shock to expand, contract and ripple.The loc…

Terrestrial Planet
One of four rocky planets found within the inner solar system. They are Mercury, Venus, Earth and Mars. They are distinguished from the gas giants by their smaller diameters, higher densities and tenuous atmospheres.

Tertiary Logic
An experimental technology in which logic gates are based on three distinct voltage levels. The three voltages are used to represent the tertiary digits 0, 1, and 2, and their logical equivalents FALSE, TRUE, and MAYBE.

tesla
The SI unit of magnetic flux density, named after Nicola Tesla. 1T is equal to 1 weber per square meter in the mks (meter-kilogram-second) system . The average magnetic field strength of the earth is 0.00005 T or 0.5 G. A long straight wire carrying 100 A of current produces a magnetic field of 0.001 T (10 G) at a distance of 2 cm from the wire.. T…

Tetrad
Unit of quantity equal to four.

Tetrafluoromethane
Colourless and odourless gas, used in circuit board manufacture, manufacture of insulating materials and semiconductors. Also used as a low temperature refrigerant. Symbol CF₄ Also known as Carbon Tetrafluoride, Freon-14, Perfluoromethane

Tetrode
A four-electrode tube or transistor. See also: Transistor.

Thallium
Thallium is a soft, silvery-grey, reactive metal which is only found as a minor constituent of various minerals (it has an abundance of 0.6 ppm in the earth`s crust), from which the metal is obtained by electrolytic reduction in aqueous solution. Thallium tarnishes readily in moist air and reacts with steam to form TlOH. It is readily soluble in ac…

Theodolite
A theodolite is an instrument used in surveying for measuring horizontal and vertical angles.

Theorem
A theorem is a statement that has been proven to be true. See also: Lemma, Logic.

Therm
Unit of energy in the British and American system of units. Mainly used within the gas industry. One therm can be provided by roughly 96.7 cubic feet of natural gas.Conversions1 calorie=4.1868 joules1 kilowatt hour=3.6x10⁶ J1 therm (EEC)=105.506x10⁶ J1 therm (US)=105.4804x10⁶ J1 thermie=4.185407x10⁶ J1 th…

Thermal Conduction
The transfer of thermal energy by collisions of the atoms or molecules within a substance.Thermal conductivity varies with temperature, but we will consider it constant in this class. The conductivity of most solids falls with increasing temperature but for most gases it rises with increasing temperature.It is measured by recording the heat flux fl…

Thermal Cycling
Subjecting a product to pre-determined temperature changes, between hot and cold extremes. See also: Thermal Shock.

Thermal Diffusivity
The ratio of heat conducted to the heat stored per unit volume.whereD = thermal diffusivity [m²s^-1]k = thermal conductivity [Wm^-1K^-1]? = density [kgm^-3]C_p = specific heat at constant pressure [Jkg^-1K^-1]