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


Metric Ounce
A unit of mass, equal to 25 grams. Also known as a mounce. See also: gram, Ounces.

Metric Sabin
This is the product of surface area and absorption coefficient. Therefore, the absorption within a room may be specified by a single number. One metric sabin is the equivalent to one square metre of a perfectly absorptive surface. See also: Average Room Absorption Coefficient, Sabin.

Metric Threads
Metric CoarseSize [mm]Pitch [mm]Tap drill [mm]Clearance drill [mm]1.00.250.75 1.10.250.85 1.20.250.95 1.40.31.1 1.60.351.251.81.70.351.3 1.80.351.45 20.41.62.42.20.451.75 2.50.452.052.903.00.52.53.403.50.62.93.904.00.73.34.504.50.753.7 50.84.25.506156.60716 81.256.89.091.257.8 101.58.512.0111.59.5 121.7510.214.01421216.01621418.0182.515.5 202.517.5…

Mho
The unit of conductance, transconductance, or admittance; it is the word ohm spelled backwards. See also: Conductance, Statmho.

Mica
A group of silicates with similar chemical composition. Used as an electrical insulator.

Micro Electro Mechanical Systems
A technology dealing with building mechanical structures on silicon wafers using integrated circuit processing techniques. See also: Integrated Circuit.

Microcomputer
One integrated circuit or a collection of integrated circuits including a microprocessor that make a computer. These components usually reside on a single printed circuit board.

Microgravity
The condition of near weightlessness induced by free-fall or unpowered space flight. It also refers to the scientific discipline concerned with the evaluation of the processes in a near-zero gravity environment, particularly those of fluid physics, life, and material sciences.

Microhardness
The hardness of microscopic areas or of the individual microconstituents in a metal, as measuredby such means as Tukon, Knoop or scratch methods.

Micrometeorology
The detailed study of the weather at a specific location.

Micrometer
An instrument used to measure the size of a body. See also: Caliper, Combination Square, Depth Micrometer, Dial Indicator Gauge, Vernier, Vernier Caliper.

Micron
A derived SI Unit of length. Through common usage 10-6m has been named the micron.1 micron (µm) = 10-6mHuman hair is approximately 20 microns in diameter.

Microphone
An acoustical-electrical transducer by which sound waves in air may be converted to electrical signals.

Microprocessor
The single integrated circuit or the portion of a single-chip microcomputerthat implements the processor and control unit of a microcomputer. See also: Central Processing Unit, Computer, Memory, Microcomputer.

Microscopic
Micro comes from the Greek word mikros meaning small. In the everyday world the word microscopic is used to refer to objects that are too small for the unaided eye to see.

Microshock
Small discharges sometimes experienced when touching a metal object in an electric field, similar to touching a door knob after walking across a nylon carpet.

Microstructure
The structural features of an alloy that are subject to observation under a microscope. See also: Macrostructure.

Microwaves
Electromagnetic waves longer than infra-red but shorter than radio, in the region of the spectrum between about 3x108Hz and 3x1011Hz and wavelengths between about 10-4m and 1m. See also: Wavelength.

Mie Potential
m, n = positive integers, n>m dominates as and this positive term goes to zero more quickly as

mil
American name for one thousandth (0.001) of an inch (1 mil = 25.4 microns).ttle='mil';xiunt='m';yiunt='mil';mconv=25.4e-6;cconv=0.0; See also: Inches, Thou.

Milankovich Theory
Theory by which ice ages were caused by slow changes of the motion of the Earth in space, including the coupling between the 26 000 year cycle of the precession of the equinoxes and the annual variation of the Earth-Sun distance.

Mild Steel
A term used for low-carbon machine steel.

Mile
A unit of distance most commonly used in Britain and the US.Abbreviation: miConversions1 mile=1609.344 metres1 mile=5280 feet1 mile=80 chains (Gunter)1 mile=8000 links (Gunter)1 mile=1.609344 kilometres1 mile=320 rods1 mile=1760 yards1 mile=0.869 nautical milesttle='Mile';xiunt='m';yiunt='mile';mconv=1609.344;cconv=0.0; See also: Chain, Foot, Furlo…

Miles per Hour
Traditional British unit of velocity used by land based vehicles.Conversions1 mile per hour (mph)=1.609 kilometres per hour (kph)1 mile per hour (mph)=0.44694 ms-1ttle='Velocity';xiunt='mph';yiunt='ms-1';mconv=2.2374145;cconv=0.0;ExamplesSnail0.03 mph (0.013 ms-1)Fast walk4 mph (1.79 ms-1)Stephenson's Roc…

Milk
Opaque white liquid secreted by female mammals for feeding young.

Mill
A milling machine. Also, the act of performing an operation on the milling machine.Climb MillingA method of milling in which the work table moves in the same direction as the direction of rotation of the milling centre. Sometimes called down cutting or down milling. Down FeedA seldom used method of feeding work into milling cutters. The work is fed…

Mill Edge
The edge of strip, sheet or plate in the as rolled state.

Millennium
Unit of time equal to 1000 years. See also: Bimillennium, Time.

Miller Indices
A set of three integers that designate crystallographic planes, as determined from reciprocals of fractional axial intercepts. See also: Crystal, Lattice, Miller-Bravis Indices.

Miller-Bravis Indices
A set of four integers that designate crystallographic planes in hexagonal crystals. See also: Crystal, Hexagonal Close Packed, Lattice, Miller Indices.

Millikan Oil Drop Experiment
A famous experiment designed to measure the electronic charge. Drops of oil were carried past a uniform electric field between charged plates. After charging the drop with x-rays, he adjusted the electric field between the plates so that the oil drop was exactly balanced against the force of gravity. Then the charge on the drop would be known. Mill…

Million
A number equal to 106. See also: Billion, Thousand.

Millisecond
One thousandth of a second, abbreviated ms or msec. See also: Second.

millivolt
Abbreviated as mV. A unit of electrical potential equal to one thousandth of a volt. See also: Volt.

milliwatt
Unit of power equal to 0.001 watt. See also: Watt.

Mineral Wool
Also known as rock wool.

Minima
The minima are points where the value of a function is less than other surrounding points. See also: Maxima, Maximum.

Minimum
In a sample of data, the smallest observation. See also: Maximum.

Minor Axis
The minor axis of an ellipse is its smallest chord. See also: Major Axis.

Minority Carriers
The conduction band holes in n-type material and valence band electrons in p-type material. Most minority carriers are produced by temperature rather than by doping with impurities. See also: Semiconductor.

Minuend
A number from which another number is to be subtracted. See also: Subtraction, Subtrahend.

Minus
The symbol: -

Minute
The main definition for the minute is as 60 seconds within the definition of time. However, it is also defined as 1/60 of a degree.Unit of Time1 minute = 60 seconds.1 sidereal minute = 59.83617 seconds.Angle1 minute = 60 seconds = 1/60 degree (°)

Mirage
An optical effect that produces an image that looks like it has been reflected from the surface of a body of water. See also: Fata Morgana, Inferior Mirage.

Mismatch Loss
The loss of power delivered into a load as a result of the interconnection of devices having unequal impedances. See also: Impedance.

Missing Fundamental
The phenomenon by which an observer, presented with a harmonic tone in which the fundamental is absent, hears the same pitch as would be heard if the fundamental had been present. Therefore, only some of the harmonics are needed to hear the pitch. The pitch that is heard when the fundamental is absent is called periodicity pitch because the period …

Mixed Dislocation
A dislocation that has both edge and screw components. See also: Dislocation Line, Edge Dislocation.

Mixture
Two or more substances which are not chemically bonded together. See also: Chemical Stability, Chromatography, Column Chromatography, Component, Compound, Eutectic Mixture.

Mobility
ElectronicsThe ratio of the carrier velocity to the applied electric field.MechanicalVelocity per unit force. The Point Mobility is the velocity at a point per unit force at the same point and same direction.

Modal Analysis
The process of determining a set of generalized coordinates for a system such that the equations of motion are both inertially and elastically uncoupled. More commonly, it is a process of determining the natural frequencies, damping factors, and mode shapes for a structure. This is usually done either experimentally through frequency response testi…

Mode
AcousticsA room resonance. Axial modes are associated with pairs of parallel walls. Tangential modes involve four room surfaces and oblique modes all six surfaces. MathematicsThe most frequently occurring value in a sequence of numbers. OpticsA term used to describe how the power of a laser beam is geometrically distributed across the cross-section…

Mode Shape
The relative position of all points on a structure at a given natural frequency. See also: Modal Analysis, Node, Vibration.

Model
A copy of an object that is n times smaller than the fullsize object. See also: Mathematical Model.

Modem
A device whose name combines the term 'modulate' with 'demodulate' which refers to its ability to transmit and receive data superimposed on a carrier frequency.

Moderator
A material used to slow down the neutrons in a nuclear reactor, thus increasing their chances of being obsorbed by a fissile material.Some of the materials used as moderators are:graphiteheavy waterwater

Modular Number System
A number system represented best by numbers on a circle because the numbers repeat. The numbers on a clock face are an example.

Modulus
The absolute value of a quantity, not considering it's sign or direction. For example, .

Modulus of Rupture
Breaking strength in a non-ductile solid as measured by bending.The modulus of rupture is the maximum surface stress in a bent beam at the instant of failure. It is always larger than the tensile strength by a factor of about 1.3.The Modulus of Rupture strictly only applies to brittle materials.

Mohs
A hardness scale developed by F. Mohs in 1812 where the hardness of a material is compared with that of a mineral. Any mineral is able to mark any other below it on the Mohs scale.MohsMineral1Talc2Gypsum3Calcite4Fluorite5Apatite6Orthoclase7Quartz8Topaz9Corundum10Diamond

Moire Fringes
A pattern formed by the interference between two regular sets of divisions.Parallel Patternwheredm = Moire fringe spacing [m]d1 = grating 1 spacing [m]d2 = grating 2 spacing [m]Rotated Patternwheredm = Moire fringe spacing [m]d = grating spacing [m]? = relative rotation angle between gratings where -p/2=?…

Molar Gas Constant
R = 8.31441 JK-1mol-1ttle='Molar Gas Constant';consttxt='R';constval=8.31441;constunt='JK-1mol-1'; See also: Boltzmann's Constant, Gas, Molar Volume, Mole, Specific Gas Constant.

Molar Heat Capacity
The amount of heat required to raise the temperature of 1mol of a substance through 1K.Units of molar heat capacity are Jmol-1K-1

Molar Volume
The volume occupied by one mole of a substance under specified conditions. For an idealgas at stp:Vm = 22.41410x10-3 m3mol-1ttle='Molar Volume';consttxt='Vm';constval=22.41410e-3;constunt='m3mol-1'; See also: Molar Gas Constant, Molar Heat Capacity, Mole.

Mole
The SI unit of Amount of SubstanceThe SI unit of the Amount of Substance is the mole. It is the amount of substance of a system which contains as many elementary entities as there are atoms in 0.012 kilogram of carbon 12. The elementary entities must be specified and may be atoms, molecules, ions, electrons or specified groups of particles.

Mole Fraction
The number of moles of a particular substance expressed as a fraction of the total number of moles.ExampleThe mole fraction of oxygen in air is about 0.21, which means that 1 mol of air contains about 0.21 mol O2.

Molecular Formula
Shows the number of atoms of each element present in a molecule e.g. H2O See also: Atom, Structural Formula.

Molecular Geometry
Shape of a molecule, based on the relative positions of the atoms.

Molecular Sieve
A material that contains many small cavities interconnected with pores of precisely uniform size. Molecular sieves adsorb molecules that are small enough to pass through their pore systems- especially water. They are often used as drying agents, and to separate large molecules from smaller ones in preparatory work and in exclusion chromatography.Ex…

Molecular Weight
The combined weight (as given on the periodic table) of all the elements in a compound. In chemistry the words mass and weight are both used interchageably.Atomic and Molecular WeightsClick on an item to paste into clipboard or use clipboard symbol at end to clipboard all values Acetaldehyde 44.05 gmol-1Clip Actinium 227.0278 gmol-1…

Molecule
The smallest part of an element or of a covalently bondedcompound that can exist independently and still retain the ordinarychemical properties of that element or compound. See also: Absorption Spectrum, Intermolecular Forces, Intramolecular Forces, Ion Dipole Forces, Molecular Weight, Orbital.

Molybdenum
Molybdenum is a lustrous silvery coloured metal. In many instances, it shows a resemblance to tungsten with which it tends to be paired in the transition series in the periodic table, but their chemistries tend to show more distinct differences than might be expected. Molybdenum has a high melting point and applications for the pure metal take adva…

Moments of Inertia
Moment of inertia has two distinct but related meanings:it is a property of a an object relating to the magnitude of the moment required to rotate the object and overcome its inertia.A property of a two dimensional cross section shape with respect to an axis, usually an axis through the centroid of the shape.

Monatomic Ion
An ion formed from a single atom by the loss or gain of electrons. See also: Electron, Ion.

Monel
Strong and corrosion resistant. Applications include: turbine blades, propellers, pump fittings, condenser tubes.... 29.15% Copper 68.44% Nickel 0.06% Silicon 1.19% Iron 1.02% Manganese 0.12% Carbon 0.008% Sulphur. Originally produced directly from a copper-nickel ore.

Monochromatic
Radiation that has a single wavelength. See also: Frequency, Wavelength.

Monomer
A molecule that, under the correct conditions, can link together with others to form larger molecules called polymers. A monomer must be capable of forming two or more bonds to other monomers.A molecule consisting of a single mer.Common monomers:vinyl acetatestyrenebutadienevinyl chloride

Monomial
An algebraic expression consisting of just one term.

Monophonic
Single-channel sound.

Monoplane
An aircraft with one set of wings.Early monoplane designs used wire braces or rigid struts to improve the strength of the wing.

Monostable
Circuit with two states. Only one state is stable. See also: Astable, Bistable.

Monotone
A sequence is monotone if its terms are increasing or decreasing.

Monotonic
Designating sequences, the successive members of which either consistently increase or decrease but do not oscillate in relative value. Each member of a monotone increasing sequence is greater than or equal to the preceding member; each member of a monotone decreasing sequence is less than or equal to the preceding member.

Moon
The Earth's moon. Galileo observed the moon through a telescope and thought that the dark areas were seas. This is why some areas of the Moon are named as seas.A view of the Apollo 11 lunar module 'Eagle' as it returned from the surface of the moon to dock with the command module 'Columbia'. 21 July 1969Click on an item to paste into clipboard or u…

Moore's Law
Gordon Moore wrote an article for the 35th anniversary issue of Electronics magazine, published in April 1965 describing the future of electronics. Integrated circuits at the time were limited to 30 transistors, but Moore`s research team was finishing a component with 60 transistors. Balancing innovation and economic factors, Moore wrote that the n…

Morse Code
The International Morse Code used to transmit signals by wire or by radio using short and long duration signals. The short duration is shown as a dot and the long duration signal as a dash.

Morse Taper
A self-holding standard taper largely used on small cutting tools such as drills, end mills, and reamers, and, on some machines, spindles in which these tools are used.

Mossbauer Spectrometer
An instrument that provides information on the bonding of an atom in a mineral by bombarding it with gamma rays and measuring small shifts in the velocity or energy of the gamma rays emitted.It is most commonly used to identify the nature of iron in a mineral.

Most Significant Bit (MSB)
The bit within a digital word that represents the biggest possible single-bit coded value. See also: Binary Notation, Bit, Least Significant Bit (LSB).

Motion Sickness
Motion sickness is defined specifically to describe nausea, vomiting and colour changes. It does not include discomfort.Motion sickness caused by vertical oscillation occurs at frequencies below 0.5 Hz. Human insensitivity to motion sickness caused by vertical vibration above this frequency is attributed to habitation because such oscillations occu…

Moving Average
The average of the most recent n data values, where n is the 'order' or 'span' of the moving average. This is one of the methods often used for forecasting time series data. Large values for n give good results for very stable series. Smaller values are needed for series which tend to change level frequently. See also: Average.

Muddy
A listening term, a sound that is poorly defined, sloppy or vague. For example, a 'muddy' bass is often boomy with all the notes tending to run together.

Multimeter
Electronic meter that displays voltage, current and resistance.

Multiple
The integer b is a multiple of the integer a if there is an integer d such that b=da. See also: Integer.

Multiple Thread Screw
A screw made of two or more threads to provide an increased lead with a specified pitch. See also: Thread.

Multiplication
Symbol : In arithmetic, multiplication of one number, a, by another, b, consists of adding a to itself b times. This kind of multiplication is commutative, i.e. . The identity element for arithmetic multiplication is 1, i.e. multiplication by 1 produces no change. In a series of multiplications the order in which they are carried out makes no diff…

Multivibrator
A building block in which the output is either High or Low. There are three foms of multivibrator: Monostable, bi-stable and astable. The monostable has only one stable state, the bi-stable has two stable states and the astable is free-running (no stable states).

Mumetal
An alloy of high magnetic permeability containing up to 78% nickel with iron, copper and manganese.

Muntz Metal
Stonger than normal brass and used for castings and hot worked items 60 % Copper 40 % Zinc. Developed in 1832.

Muon
The second flavour of charged leptons (in order of increasing mass oftencalled a heavy electron), with electric charge -1.Click on an item to paste into clipboard or use clipboard symbol at end to clipboard all values muon mass 1.88353109e-28 kgClip muon-electron mass ratio 206.7682657 Clip muon-tau mass ratio 5.94572e-2 Clip muon-proton mass ratio…

Music Wire
Another name for piano wire, a high quality steel wire used for making springs.