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 The information may have been taken offline because it is outdated.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


Roses Alloy
A fusible alloy consisting of 50 per cent bismuth, 25 percent lead and 25 per cent tin.

Rosin
Natural resin obtained from living pine trees or from dead tree stumps and knots.

Rotary Engine
The crankshaft is fixed and the crankcase, pistons and cylinders rotate with the propeller.Rotary engines were used extensively in early aircraft. See also: Engine Configurations, Radial Engine.

Rotation
Motion of an object where the path of every point is a circle or circular arc. A rotation is defined by a point and vector which determine the axis of rotation. The direction of the vector is the direction of the axis and the magnitude of the vector is the angle of rotation. See also: Isometry, Plane Angle, Vector.

Rotational Inertia
The property of an object that measures its resistance to a change in its rotational speed. See also: Angular Velocity, Inertia.

Rotational Kinetic Energy
The energy a body possesses due to it's rotation about an axis.whereT = rotational kinetic energy [J]I1, I2, I3 = principal moments of inertia [kgm2]?1, ?2, ?3 = components of angular velocity along principal axis [rads-1]

Roughing
The fast removal of stock to reduce a workpiece to approximate dimensions. leaving only enough material to finish the part to specifications. See also: Lathe.

Round-Off Error
The error accumulated during a calculation due to rounding intermediate results.

Rubidium
Rubidium is a soft and highly reactive member of the alkali group of metals. It is widely distributed throughout nature, but only occurs in small amounts, the main source being carnallite, the hydrated chloride of magnesium and potassium. The metal is obtained by the electrolysis of the fused halide, although it can be obtained on a laboratory scal…

Rubidium Bromide
White crystalline solid. Symbol RbBr

Rubidium Chloride
White crystalline solid. Symbol RbCl

Rubidium Fluoride
White crystalline solid. Symbol RbF

Rubidium Hydride
White crystalline solid. Symbol HRb

Rubidium Iodide
White crystalline solid. Symbol RbI

Rubidium Oxide
Yellow to yellow brown crystalline solid. Symbol Rb2O

Rubidium Peroxide
White, yellow or dark brown crystalline solid. Symbol Rb2O2

Rubidium Sulphide
White, yellow or red. Symbol Rb2S

Rubidium Superoxide
Orange crystalline solid. Symbol RbO2

Rudder
The moving part of the vertical tail surface of an aeroplane which provides yaw control or the device in the water on a boat that provides directional control.A boat rudder.Aircraft rudder. Forces the tail left or right, correspondingly yawing the aircraft right or left. Rudder movement coordinates with the banking of wings to balance a turn. See a…

Ruled Surface
A surface formed by moving a straight line.

Ruler
Photograph courtesy of Draper.co.ukA straight edge with graduation marks used to measure and draw or cut straight lines. See also: Scribe.

Running Fit
A class of fit intended for use on machinery with moderate speeds, where accurate location and minimum play are desired. See also: Fit.

Running Modes
This is a term used for watching the dynamic behaviour of a system during it's normal mode of operation. In vibration terms the motion is normally measured using accelerometers in the time domain and then Fourier Transformed into the frequency domain so that the motion at certain frequencies may be observed. This frequency may be related to a certa…

Rupture
Failure that is accompanied by significant plastic deformation. See also: Plastic Deformation.

Rust
A corrosion product consisting of hydrated oxides of iron. This term is only applied to ferrous alloys. See also: Iron, Iron II Oxide, Iron III Oxide, Steel.

Ruthenium
Ruthenium is a rare member of the platinum group of metals. It is a lustrous, silvery coloured metal which is unaffected by air, water and acids, but is soluble in fused alkalis. Extraction of the metal is achieved by several techniques; for example, extraction of the mixed platinum group metals by dissolution in aqua regia, followed by treatment o…

Rydberg Constant
A constant which governs the relationship of the spectral line features of an atom through the Rydberg formula.R = 1.0973731568549x107m-1ttle='Rydberg Constant';consttxt='R';constval=1.0973731568549e7;constunt='m-1';Also,Rc = 3.289841960368×1015 HzRhc = 2.17987190×10-18 Jwherec = speed of light…

Sabin
The unit of measure of sound absorption in the inch-pound system. A measure of the sound absorption of a surface. One sabin is the equivalent to one square foot of a perfectly absorptive surface.Named after Wallace Clement Sabine, the Harvard professor honoured as the 'father of architectural acoustics' for his investigations into concert hall soun…

Sabine, Wallace Clement
The Harvard professor honoured as the father of architectural acoustics for his investigations into concert hall sound at the turn of the century. See also: Sabin.

Saccade
The normal, but largely unnoticed rapid darting of the eyes from one fixed point to another.

SAE Steel
Steel manufactured under the specifications by the Society of Automotive Engineers. See also: Steel.

Safety Pin
A simple pin that clips shut most commonly used to fasten two pieces of fabric.The safety pin was invented by Walter Hunt in 1849. He patented the safety pin on April 10, 1849 (patent No. 6,281). Hunt's pin was made by twisting a length of wire. He invented the safety pin in order to pay a debt of $15, he eventually sold the rights to his patent fo…

Sag
Deflection due to gravity acting on a cantilevered or otherwise supported object. Mechanical brackets that hold alignment tools always sag a certain amount. This sag must be corrected if the machine moves are to calculated correctly.

Sagnac Effect
First discovered in 1913 by Georges Sagnac, it involves sending two beams of light in opposite directions around a closed path and then using a detector to examine the beams when they arrive back at the starting point.If the light path, light source and detector is stationary then both beams will reach the detector at the same time. The beams will …

Salts
Ionic compounds that can be formed by replacing one or more of the hydrogen ions of an acid with another positive ion. However, salts may be more usefully considered as ionic compounds in which the ionizable hydrogen ions of an acid have been replaced by either metal or ammonium ions. A monoprotic acid, such as ethanoic acid, has one ionizable hydr…

Samarium
A lanthanide group element, samarium is a silvery-white metal which is found in the minerals allanite, cerite, gadolinite and its namesake, samarskite. It is relatively stable in dry air but oxidises on contact with moisture. Applications of the metal are limited, but it finds uses in the glass, ceramics and electronics industries and also in the m…

Sample
A set of observations, usually considered to have been taken from a much larger population. Statistics are numerical or graphical quantities calculated from a sample. Since the data in one sample will vary from that of another, so will the statistics calculated from those samples.A sample is generally selected for study because the population is to…

Sampling Frequency
The frequency or rate at which an analog signal is sampled or converted into digital data. Expressed in Hertz. See also: Frequency, Hertz, Sample.

Sand
A term generally given to rock with a grain size between 1/16mm and 2mm.

Sandblasting
A process of blowing sand by compressed air with considerable force through a hose against an object. See also: Shot Blasting.

Sandpaper
Photograph courtesy of Draper.co.ukAn abrasive paper used to smooth the rough edges of freshly sawn wood. Also known as glasspaper. See also: Abrasive, Emery Cloth, File, Wire Brush.

Sapid
To have a decided, yet pleasant taste.

Saponaceous
To be soapy, slippery, sometimes foaming.

Satellite
An object in an orbit around a planet. It can be either natural, for example a moon, or it can be artificial, for example a space probe.Historical Notes1610 Jupiter's satellites discovered by Galileo.4 October 1957 Sputnik becomes the first man-made object to orbit the Earth.4 January 1958 Sputnik 1 fell back to earth.31 January 1958 USA launches i…

Saturated Liquid
Purely liquid, but at the saturationtemperature any additional heat will cause some vapourisation. See also: Liquid.

Saturation Velocity
Maximum velocity which can be obtained in a specific semiconductor.

Saturn
The sixth 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 120536000 mClip Average Density 690 kgm-3Clip Axial tilt 26.7 degreesClip Rotational period 10.67 hoursClip Average surface temperature -180 °CClip Maximum apparent magnitud…

Saw
A tool with a blade or disc with teeth along the edge used to cut metal, wood, plastic and many other materials. There are many different types of saw:BandsawPhotograph courtesy of Draper.co.ukA power saw, the blade of which is a continuous, narrow, steel band having teeth on one edge and passing over two large pulley wheels.Bow SawPhotograph court…

Scalar
Any quantity that has only magnitude as opposed to both magnitude and direction. For example mass is scalar quantity. By convention in physics the word speed is a scalar quantity, having only magnitude, while the word velocity is used to denote both the speed and the direction of the motion and is thus a vector quantity. See also: Vector.

Scale Effect
Any variation in the nature of the flow and in the force coefficients associated with a change in value of the Reynolds number, i.e., caused by change in size without change in shape. See also: Reynolds Number.

Scalene Triangle
A triangle in which no two sides are of equal length.

Scandium
Scandium is a soft, silvery white metal. It has been identified in several minerals, including cerite, orthite, thertveitite, wolframite and euxenite (a niobate, tantalate and titanate of several rare elements in which scandium was originally discovered). It is a metal which tarnishes in air (shows a pink colouration), burns easily and reacts with …

Scattering
The irregular diffraction and reflection of waves in many directions. See also: Diffraction, Reflection.

Schlieren
An optical technique that detects density gradients occurring in a fluid flow. Schlieren is a German word that means 'striations.' It refers to various shadowgraphic techniques for optical investigations. Variations in density in flow through shock waves and supersonic flow, for example, are sharply visible in tonal gradations. See also: Shadowgrap…

Schmitt Trigger
A building block in which the input must be taken to about 70% of rail voltage before the output will change. The lower level for change is about 30%. This produces a gap and thus noise is prevented from entering. See also: Transitive.

Schneider Index
A composite weighted index of pulse and blood-pressure response to exercise, utilized as a test of physical efficiency.

Schottky Diode
A diode using an aluminium-silicon junction in which carrier storage is negligible, leading to very fast on and off states and thus very fast switching speeds. The foward voltages is 0.3v. Also known as a 'hot-carrier diode' or a 'surface-barrier diode'. See also: Diode, Zener Diode.

Schrödinger Equation
The basic equation of quantum mechanics. In time-dependent form, it describes the evolution of atomic-scale motions and is widely used by chemists studying the dynamics of chemical reactions.

Schrödinger, Erwin (1887-1961)
Austrian physicist; developed atomic theory of wave mechanics (1926); shared Nobel Prize for physics with Paul Dirac in 1933.Famous Quotes:'I do not like it, and I am sorry I ever had anything to do with it.' When talking about quantum mechanics.

Schuler Pendulum
A hypothetical pendulum with a period of 84 minutes. A simulated Schuler pendulum carried in a vehicle moving in the earth's gravitational field would always indicate the true vertical.Schuler TuningAdjusting a system performing the function of a pendulum so that is has a period of 84 minutes.

Schwarzschild Black Hole
A nonrotating, spherical black hole that has no electric charge. See also: Black Hole, Kerr Black Hole.

Scientific Notation
Numbers entered as a number from one to ten multiplied by a power of ten.Example: 3745 = 3.745×103.

Scintillation Counter
A scintillation counter consists of a material that emits light when radiation passes through it. Various liquid, plastic, and crystalline materials have scintillation properties. Scintillation light is measured with photomultiplier tubes. In general the amount of scintillator light detected is proportional to the energy of the radiation. See also:…

Score
Twenty pieces of something.

Scraper
A hardened steel hand tool used to scrape surfaces very smooth by removing minute amounts of metal.

Screw
A helical projection of uniform section on the internal or external surface of cylinder or cone. See also: Bolt, Screw Thread, Thread, Wood Screws.

Screw Thread
A ridge of constant section which is manufactured so that a helix is developed on the internal or external surface of a cylinder. See also: Screw, Thread.

Screwdriver
A tool that locates on the head of a screw and allows a torque to be applied to turn it.Angled ScrewdriverPhotograph courtesy of Draper.co.ukAn angled screwdriver is useful when there is not enough space to get access to with a normal straight screwdriver.Cordless ScrewdriverPhotograph courtesy of Draper.co.ukA battery powered handheld screwdriver …

Scribe
A steel rod 8 to 12 inches long and about 3/16 inches in diameter. It has a long, slender, hardened steel point on one or both ends. See also: Ruler.

Scruple
An old unit of weight.Conversions1 scruple=1/24 ounce troy1 scruple=20 grains1 scruple=1.295978x10-3kg3 scruples=1 drachmttle='Scruple';xiunt='kg';yiunt='scruple';mconv=1.295978e-3;cconv=0.0; See also: Grain, Ounces.

SEA Coupling Loss Factors
Using the consistency relationship for coupling between any two subsystems, eta1eta12 = eta2eta21.Plate to Room/CavityRoom to PlateCavity to PlateRoom to Room/Cavity (non resonant)Cavity to RoomPlate to Plate (line)Structure to Structure (point)whererho0 = density of air [kgm-3]rho
Sea Water
Contains the majority of the common elements in small quantities.

Seaborg, Glenn T. (1921- )
American nuclear chemist.1951 shared Nobel Prize for chemistry with Edwin Mattison McMillan for the discovery of Plutonium.

Sealing Wax
The wax used to seal confidential documents.

Secant
Note: In this series A is in radians and See also: Cosecant, Cosine, Cotangent, Series Expansions, Sine, Tangent.

Secant Line
A line that intersects a curve or circle in two places.

Second
The main definition for the second is the SI unit of time. However, it is also defined as 1/360 of a degree.The SI unit of TimeThe SI unit of time is the second and is the duration of 9192631770 periods of the radiation corresponding to the transition between two hyperfine levels of the ground state of a caesium 133 atom.Angle1 second = 1/360 degre…

Second Law of Thermodynamics
Clausius statementNo process is possible whose sole result is the transfer of heat from a colder to a hotter body.Kelvin-Planck statementNo process is possible whose sole result is the absorption of heat from a reservoir and the conversion of all of this heat into work.Carnot's theorems:i)No engine can be more efficient than a reversible engine wor…

Second Order Reaction
A reaction with a rate law that is proportional to either the concentration of a reactant squared, or the product of concentrations of two reactants. See also: First Order Reaction, Reactants, Zero Order Reaction.

Secondary Cell
A galvanic battery which, after discharge, may be restored to the fully charged state by the passage of an electric current though the cell in the opposite direction to that of discharge. See also: Battery, Primary Cell.

Secondary Radiation
Electromagnetic or particulate radiation resulting from absorption of other radiation in matter. See also: Radiation.

Secondary Ride
A term used to indicate the ride response of a vehicle in the frequency range of 8-20 Hz. Secondary ride response is dominated by the phenomenon termed 'engine shake'. Actual mechanism involves transient or steady state vibrations of the power unit on its mounts, which can be excited by inputs from the suspension. See also: Ride Quality.

Seebeck Effect
The principle that describes how a thermocouple works. In a circuit in which there are junctions between dissimilar metals, an electromotive force (voltage) is set up when the junctions are at different temperatures. See also: Thermocouple.

Seiche
An oscillation of a fluid body in response to a disturbing force having the same frequency as the natural frequency of the fluid system. Tides are now considered to be seiches induced primarily by the periodic forces caused by the sun and moon.

Seismic
Of or having to do with earthquakes. See also: Mercalli Scale, Richter Scale, Seismograph, Volcanoes.

Seismograph
An instrument for detecting and recording the intensity, direction, and duration of a movement of the ground caused by an earthquake or explosion. See also: Mercalli Scale, Richter Scale, Seismic.

Selenium
Selenium exists in several allotropic forms; red selenium is monoclinic and contains Se8 rings. It has a melting point of 180°C and a relative density of 4.45. The grey (metallic) form of selenium is formed when other varieties are heated to 200°C; this has a melting point of 220°C and a relative density of 4.80. The metal burns in air a…

Selenoid
A satellite of the earth's moon, no such satellites are known. See also: Earth, Moon, Satellite.

Selenology
That branch of astronomy that treats of the moon, its magnitude, motion, constitution, and the like.Selene is Greek for moon.

Self Discharge
The loss of useful capacity of a cell or battery due to internal chemical action. See also: Battery.

Self Extinguishing
A material which will not supportcombustion when external source of flame is removed.

Self Noise
Extraneous non-acoustical signals, generated or induced in a measurement system. Take just about any audio system, turn it up very loud with no signal being played, and put your ear close to a speaker in a very quiet room and you will hear some hiss. See also: Noise.

Semi-Anechoic Chamber
A room which creates free field conditions but above a reflective plane.Above a certain frequency all sound waves that hit the walls or ceiling of the chamber will be absorbed.This type of chamber is normally used in vehicle testing with a rolling round so that the vehicle may be driven. The semi-anechoic chamber then forms a controlled environment…

Semiconductor
An element, such as silicon, that is intermediate in electrical conductivity between conductors and insulators, through which conduction takes place by means of holes and electrons. The conductivity of a semiconductor is changed by the addition of small amounts of impurities to its crystal structure.p-type SemiconductorA semiconductor for which the…

Semiconductor Detector
Radiation striking very pure Ge and Si semiconductor detectors can excite a large number of electrons into the conduction band leading to a measurable current. This current is proportional to the energy of the radiation. Semiconductor detectors can be used to accurately measure the energy and intensity of radiation. See also: Geiger Counter, Radioa…

Sensation Level
The level of psychophysiologic stimulation above the threshold. See also: Psychoacoustics.

Sensitivity
The greater the sensitivity, the greater the system's signal-to-noise ratio.

Separable Equations
A differential equation is separable if it can be written

Septet
A unit of quantity equal to 7.

Septillion
A number equal to 1024. See also: Octillion, Sextillion.