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McGRAW-HILL DICTIONARY OF SCIENTIFIC AND

TECHNICAL ·.TERMS

-:, I'

McGraw· Hill

New York . Chicago San Francisco Lisbon London Madrid Mexico City

Milan New Delhi San Juan Seoul Singapore Sydney Toronto

)0 p ¥

On the cover: Representation of a fullerene molecule with a noble gas atorn trapped inside. At the Permian· Triassic sedimentary boundary the noble gases helium and argon have been found trapped inside fullerenes. They exhibit isotope ratios quite similar to those found in meterorites, suggesting that a fireball meteorite or asteroid exploded when it hit the Earth, causing major changes in the environment. {Image copyright © Dr. Luann Becker. Reproduced with permission.)

Over the six editions of the Dictionary, material ha$ been drawn(l'Dm the folltiwing references: G. M. Garrity eta!., Taxonomic Outline of the Procaryote$'; Release 2; Springer-Verlag, January 2002; D. W. Linzey, Vertebrate Biology, McGraw-Hill, 2001; J. A. Pechenik, Biology of the Invertebrates, 4th ed., McGraw-Hill, 2000; U.S. Air Force Glossary of Standardized Terms, AF Manual 11-1, vol. 1, 1972; F. Casey, ed., Compilation of Terms in Information Sciences Technology, Federal Council for Science and Technology, 1970; Communications­Electronics Terminology, AF Manual 11-1, vol. 3, 1970; P. W. Thrush, comp. and ed., A Dictionary of Mining, Mineral, and Related Terms, Bureau of Mines, 1968; A DOD Glossary of Mapping, Charting and Geodetic Terms, Department of Defense, 1967; J. M. Gilliland, Solar-Terrestrial Physics: A Glossary of Terms and Abbreviations, Royal Aircraft Establishment Technical Report 67158, 1967; W. H. Allen, ed., Dictionary of Technical Terms for Aermpace Use, National Aeronauticsand Space Administration, 1965; Glossary of Stinfo Terminology, Office of Aerospace Research, U.S. Air Force, 1963; Naval Dictionary of Electronic, Technical, and Imperative Terms, Bureau of Naval Personnel, !962; R. E. Huschke; Glossary of Meteorology, American Meteorological Society, 1959; ADP Glossary, Department of the Navy, NAVSO P-3097; Glossary of Air Traffic Control Terms, Federal Aviation Agency; A Glossary of Range Termin()!og}~ White Sands Missile Range, New Mexico, National Bureau of Standards, AD 467C:424; Nuclear TrmiS: A, Glossary, 2d ed., Atomic Energy Commission.

McGRAW-HILL DICTIONARY Of SCIENTIFIC AND TECHNICAL TERMS, Sixth Edition Copyright © 2003, 1994, 1989, 1984, 1978, 1976, 1974 by The McGraw-Hill Companies, Inc. All rights reserved. Printed in the United States of America. Except as permitted under the United States Copyright Act of 1976, no part of this publication may be reproduced or distributed in any form or by any means, or stored in a database or retrieval system, without the prior written permission of the publisher.

1234567890 DOW/DOW 08765432

ISBN 0-07-042313-X

Library of Congress Cataloging-in-Publication Data

McGraw-Hill dictionary of scientific and technical terms--6th ed. p. em.

ISBN 0-07-042313-X (alk. paper) 1. Science--Dictionaries. 2. Technology--Dictionaries. I. Title: Dictionary of scientific

and technical terms.

Q123.M15 503-dc21

2002

2002026436

TECH) To remove something, especially gases from an enclosure, ,su9h as ,from, the envelope of tube, or from a welL ; Als,o known as, exhaust.

} . ' .. ,,

zoo) The ensign flit1S; afamily ofhymenop­in the superfamily Proctotrupoidea. L ,ev·<J'ui·

. ' ' Al3(P04)(0Hk6HP A .<.:olorless to

of a hydrated,basic aluminum form and as stalactites. ; (''e~·:

Conversi~~ of a liquid to the va.por state heat. { i,vap·~'ra·sh<Jn )

:;:;,;,,r;aclt•v, See .evaporative powet. ·( i,vap•<J'.ra·.

•[OCEANOGR] An · ocean current accumulation of water through precipitation one point, and loss by evaporation at.(lllother

·sh<Jp ,k<J·r<Jnt.) a1mo,Weter. { i,vap•<J'ra·sh')n ,gaj')

The loss qf a stqmd voli\;t,i.\y mixture by ·evaporat.ion;. controlled by

. . and. the presence or., absence of vapor-· [i,vap:<J'r~·sh<Jn ,los }

[EN.Q] A type of atmometer consi,sting qf measurement of the evaporation of water

\ i,vap·<J'ra·sh<Jn ,pan} See evaporative power ... { i,vaw<J'.ra·sh<Jn

[ENG] A tank used to measure theevapo­

}

c.ontrolled conditions. {i,vap·<J'ra·

[MECH ENG] An apparatus in which tJ,~bes that are cooled by the·evapora­

over the o.utside of the tubes ... { i'vap•

sys~em [MEet! ENG] A motor vehiclg MAif"''"ntc escape of gasoline vapors from. the fuel

the atmosphere ,whilesl)e engine ,is :.not ·iv k<Jn.'trol ,sis·tom }

[ENG] . 1. Lowering the \emperature of by utilizing the latent heat of vaporization

liquid. 2. Cooling airby evapor~til)g, water vaporization cooling. ( i'vap·o,rad·iv 'kiil·,

[PHYSIO]. Thecompositeproc: .body is cooled by evaporation of

:W~Wif~ pe>rsr>iration: this avenue ofhe~t loss serves as a physii .the body temperature. [i'vap:<J,rad·

·shan} . , power [METEOROl} A mea~ure ofthe degr,e.e weather or climate of a region. is favorable to the

••·••··~·~·•·')'an'''"'e,_v·a·poration; it is. qsually cqnsidered to be the rate , {;{,:1~ll!lce 0

under existing atmospheric1 condition~, from a

1~ Water which is chemically pure and has the,tempem, e lowest layer of .the, iltrnosphere. Also known as

capacity; ev~porationpower; evaporative capacity; , potential evaporation. { i'vap·o,rad·iv 'pall>

See evaporati;\f power. { i,vap·a·r<J'tiv·;:,~·e } sol [CHEM ENG] A device used to vaporiz~ part or

a so]ivent from a sqlution; the v:;tluabh;,prodp.ct is usq\[lly · A d or concentrated. solu.tion of the solute. [MECH

statny bof many devices in which liquid is changed to, 1the wa~er Y th~ addition of heat, for example, distiller, still;

Pllnf~er, or refrigeration ·system .element where

evaporation procee,ds at low pressure and consequent,low:tem­perature. (. i'vap·G·,rad·;:,r}

evaporimeter See atmometer. { i;\'ap·:l'rim·;:>d·Gr} evaporite [GEOL] Deposits of mjnetal salts from sea water or salt lakes due. to evaporation of the water. { i'vap·G,l'lt}

evaporite pond [IND ENG) Any containment area for brines or solution-mined effluents constructed to,permits0lar evapora; tion ,and har\'esting of dewatered evaporite' concentrates. (.i'vap·<J,rit • ,pand }

evapotranspiration [HY,D] Discharge· of water frorri the earth's surface to tlie atmosphere by evaporation from lakes, streams, and soil, surfaces. and by transpiration from plants. Also ktiown as fly-off; total evaporation;'water loss. .{ i,vap· o,tranz·p0'ra·sh0n}

evapotranspirometer [ENG] An instrument which ',meas­ures the rate of evapotranspiration;· consists of a vegetation soil. tank so designed that all water added to. the tank and all water left after· evapotranspiration can be measJlred. { i,vap·O,tranz.· p;:,'ram·Gch>r }

Evase stack [civ ENG] In tunnel engineering, ari exhaust stack for air.having a cross section that incre·aHes in the direction' of airflow. at a rate to regain pressure. r:a,va:z:t ,stak.J

evection [AsTROPHYS] A perturbation cif the moon in its orbit 'due to ihe attraction of the sun. { e'vekish<Jh J

E vector [ELECTROMAG] Vector representing the electric field of an ele'ctromagnetic w'ave. { 'e , vek·wr }

even-even nucleus [Nuc PHYS] A nucleus which has un even number of neutrons and an even number of protons. { :e· V<Jn :e·von ,nii·hle·<Js } · ,

even function [MATH] A function with the property that f(?:) = f( C:.x)'for each number X. . ( 'e·v;;in ,f<J\]k,sh<Jn'}

even harmonic [PHYS] A hllrmoniC that is an even multiple of the fundamental t'requency. { :e·y0n h~r,m~n·ik. )

evening gun [ ORD] Firing of a gun as a signal for the lov,:­ering of the 11ag at retreat; ihe gun is fired. afteqhe sounding ofthe last note"of the•bugle call at retreaf. Also known as retreat glm.'" l :e¥·'nio 'g011}' , · ..

evening star [ASTRON) 'A misnqmer for U planet that can be ~een witho\It a telescqpe when it set~ aft~ the sun. ( :ev· nil} ,'stiir} ' . · ·.

evening twilijjht, i [ASTRciN} The period oftime between sun­?et and dmknb.s. { :ev·niu 'twi,ln J

eve" keel [NAY AR<;H] Floating Je~el. without inclination. { )e·vM' 'kel l , · .

even nu)Ilber [MATH] J\n integerr which is a multiple of 2. { 'e·v(m ,nilip·b<Jr}

even-odd riucl~US . [NUC PHYS] A nuci~us which has an even number of ptotoris and an odd number of ne,Utrons. t:e·v<Jn lad .'nii·lde·ils 'j . .. · . . . ..

eve.n pari~y check [COMPUT sq] A parity .chec]< in which th.e nl!mb'er of. O's or l 's in each word is expected to be even. { :e·van 'par·0d·e ,chek } ·

even. rermutation [MATH] A p,ermutati911. which, may be represented as a result of an even number .of transpositions. ( :e·v;:,n p<Jr·myG'ta·sh<Jn } · ·

even pitch [DES ENGJ, The ,pitch of a screw in which the number.of threl)dS. per iiich is a multiple (Or submultiple) of tl]e threads per)nch of the lead screW of the lathe on which the screw is cut. { ie·v<Jn 'pich } . .•

event [ cOMI?UT sci l The moment of time at y;hlcl) a speci­fied change, of state occurs; usually.tjlarks the completion of an asynchronous input/output operation. [ <;JEOH An incident of probable tectonic significance, but whose full implications are. unknown. [!ND E':!G] J;.. sp~cified <)CcompJishrrient in a pro­gram at a particular time; appears as. a nqde in a graphic repre­sentation of an endeavor with a specific. objective (project), [PHYS] A point in space-time.· [STAT] A mathematical model of the result of a conceptual experiment; this model L~ a measurable subset of a probability space. { i'vent}

event-driven monitor [coMPUT sci) A computer program that measures the pprformaQ.ce of a computer system bY count­ing the tasks.performed by the system. {.i'vent ldriv·gn 'man· ad·;:,rJ

event horizon [RELAT] The boundary of aregjon ofspace­ti)Ile ~l'Ol)l which it \s.notpossibl~ to escape to. in~injty.,$ymbol-ized :J>+. {i'venthG,rfz·an l ·

Eventogn;:tthi . [vnRT zoo] The equivalent nanw for Cypriui­formes. { ,e,ven'tag·n<J,thr}

t:ventognatm r

EVAPORATOR

t feed liquor

Long-tube vertical evaporator.

Also known as instrumental conditionin~; rein­conditioning. { 'ap·;:,·r;mt k;:,n'dish·;:,·nil] r

[COMPUT SCI] The phase of computer opera7 an instruction is being carried out. [ELECI Total

time from application of energizing current to a relay ··time the contacts have opened or closed. { 'tip· }. angle [ELECTR] Electrical angle of the input sig­

portion of a cycle) during which plate cmrent a vacuum tube amplifier. ['ap·;:,,rild·iiJ ,aJ]·g;:,l}

characteristic' curve [STAr] In hypothesis test­of the probability of accepting the hypothesis against

state of nature. Abbreviated OC curve.. { 'ap:;:~,rad· ""'~····•o·hlr 'k;:,rv } .

delay [COMPUT SCI] Computer time lost because or inefficiency of operating personnel or users of excluding time lost because of defects in programs.

{ 'lip·;:~,rad·iiJ di,la ) handle [ORD] Handle or bar. with which the lever of a gun is operated to open and close the

{ 'ap·;:~,rad·iiJ ,han·d;:~l } instructions [coMPUT scr] A detailed descrip­

actions that must be carried out by a computer a program or group of interrelated programs,

in the documentation of a program supplied :ogrannmer or systems analyst, along with the source

tlow charts. { 'ap·;:~,rad·iiJ in,str;:,k·sh;:,nz ) [ORD} Lever device on a gun with which

is opened and closed. ( 'ap·;:~,rad· il]' ,lev·;:,r ] [ CHEM ENG] ln the graphical solution of equi­

(such as distillation absorption extraction), liquid-vapor relationship of a key component, in a true equilibrium relationship. { 'ap·;:,,rad·iu ,lin} point [ELECTR] Point on. a family of characteristic a vacuum tube or transistor where the coordinates of represent the instantaneous values of the ele~trode

currents for the operating conditions under study {. 'ap·;:,,rad·iiJ ,p<;iint } ,

position [coMMUN] Terminal of a communicit­channel which is. attended by an operator; usually the refers to. a single operator, such as a radio operator's

or a telephone operator's position; however, certain inay require more than 'one operating position. ·iiJ p;:,,zish·;:,n]

power [ELECTIWMAG] Power that is actually sup­radio transmitter antenna. { -'ap·;:,,rad·iiJ ,pau·;:,r] pressure . [ENG] The system pressure at which a operating. ( 'ap·;:~,racl·iiJ ,presh·;:,r )

[ELECTR] The frequency range ov6r which transducer is operable. [NAV] The maximum

which reliable service is provided by an aiel to { 'ap·a,rad·iiJ ,ranj } . ,

Iii op,er<llirlg ratio [ COMPUT sci} The time during which com· operat.es and gives reliable results divided by

time scheduled for computer operation. { ~ap·;:,,racl· J . ' •

·~··················~~'-··'''··-slide )ORD] Mechanism in a Browning machine that permits openipg the breech for loading, unloading,

and clearjng out stoppages, and closing the breech for firing. ( 'iip·;:,,rad·io ,slTd) •

Operating stress [MEet!] The stress to. which a structm'al unit is subjected in service. { 'iip·;:,}ad·irJ ,stres }

Operating sy~em [coM PUT sci) A set of programs and rou­tines which guides a computer or network in the performance of its tasks, assists the programs (and programmers) with certain supporting functions, and increas~s the usefulness of the com: puter or network hardware. { 'ap·a,rad·io ,sis·t;:>m }

0 Perating system supervisor [COMPUT sci] The control program of a set of programs which guide a compliter in the, Performance of its tasks and which assist the progra1n with certain supporting functions. { 'iip·;:~,rad·iiJ ,sis,iam ··so· P<lr,vrz.~r ] ·

0Perating water level [MECH ew;J The water level In a boiler drum which is normally maintained above the lowest safe level. { 'ap·.;:~,racl·iu 'w6d·;:,r ,Jev·gl }

0Peration [CoMPUT scr] 1. A process or proce,clure that obtains a unique result from any permissible combination of 0Perancls. 2. The sequence of. actions resulting :from the exe­cution of one digital computer instruction. [IND E~IG] A job,

operation process chart

usually performed in one location, and consisting of one or more work elements. [MAI'H] An operation of a group G on a setS is a mapping which associates to each ordered pair (g,s), where g is in G and s is in S, another element in S, denoted gs, such that, for any g,h in G and s inS, (gh)s = g(hs), an4 es = s, where e is the identity element of G. ( ,ap·;:,'ra ·sh;:,n ]

operational · ! ENG J Of equipment such as aircraft or vehicles, being in such a state of repair as to be immediately usable. { ,ap·;:,'ra·sh;:,n ·;:,I }

operational advantage [NAV] In air operations, an improvement which. benefits the users of an instrument proce­dure, such as the ability to· use lower minimums. { ,ap·;:,'ra· sh;:,n·;:,l ;:~d'van·tij } ·

operational amplifier [ELECTR] An amplifier having high direct-current stability and high immunity to oscillation, gener­ally .1.1chieved by using a large amount of negative feedback; used to perform analog-computer fimctions. such as summing and integrating. { ,ap·;:,'ra·sh;:,n·;:,l 'am·pl;:~,fi·;ir]

operational analysis :See operational calculus. {',iip·;:,'ra· sh;:,n·;:,l ;J'rial·;:>·s;:,s}

operational calculus [MATH] A technique by which prob­lems in analysis, in particular differential equations, are transo formed into algebraic problems, usually. the problem of solving a polynomial equation. Also known as operational analysis. { ,iip·;:,'ra·sh;:,n·;:,l 'kal·ky;:~·l;:,.s}

operational g,ame See management game. ( ,iip·;:,'rii·sh;:,n· ;:~l'gam l

operational label [coM PUT sCI] A combination of letters and digits at the beginning of the tape which uniquely identify the tape ryquired by the system. { ,ap·;:,'ra·sh;:,n·;:,l 'la·b;:~l }

operational malntllnance [ENG] The clea!ling, servicing, preservation, lubrication, inspection,. and adjustment of equip: ment; it includes that minor replacement of parts not" requiring high technical skill, internal alignment, or special locative train­ing. { ,iip·;:,'ra·sh;:,n-;:,1 'mant·,;:,n·;:,ns }

operational standby program [coMPUT sci] The program operating in the standby computer when !11 the dup)ex )I!Ode of opeimion. { ,iip·;:,'ra·sh;:,n·;:,l 'stancl,br ;pro,gram}

operational unit [GEOL]' An arbitrary stratigraphic unit that is clistinguishecll:)y objective criteria for some practical purpose. , ~]so known as parastratigraphic unit: { ,ap·;:,'ra·siJ;:,n·;:,l 'yii·n;:,t}

operational weather limits [METEOROL] The limiting val­ues of ceiling, visibility, and wind, or runway visual' range,' established as safety minima for aircraft hindings ariel takeoffs. { ,iip·;:,'ra·sh;:,n·;:,l 'wefu·;:,r ,lim·;:,ts ]

operation analysis [IND ENG] An analysis of all procedures concerned with the design or improvement of production, the purpose of the operation, inspection standards, materials used and the manner of handling them, the setup, tool eqliipment, and working conditioJL~ and methods. { ,ap·;:,'ra·sh;:,n ;:~'nal· ;)·S;:>S} . .. ,

operation analysis chart I IND ENG] A form that lists ,all the essential factors influencing the effectiveness of an operation. { ,iip·;:,'ra·sh;:,n ;:,'nal·;:,·sos ,chart}

operation breakdown See job breakdown. [. ,ap·;:,'ra·sh;:,n 'brak,diuln }

operation code [ COMPUT scr] A field or portion of a digital computer instruction that indicates which action is to be per­formed by the computer. Also k11own .as command code, { ,iip·;:,'ra·sh;:,n ,kiicl } ..

operation cycle [coMPl.IT sci] The portion of a memory ~ycle require<) to perform an operation; division and m~ltiplica­tion. usually require !)lore than one memory cycle to be 'com-pleted. { ,ap·;:,'ra·sll;:,n ,si:k;:,] ) ·

operation decoder [COMPUT sc1] A device (hat examines the operation contained in an instruction of a computer program and sends signals to .the circuits required to carry out the opera­tion: { ,ap·;:,'rli·shim de'kocJ·;:,r }

operati6n number [ COMPUT SCI] . ' 1. Number designating the position 'of an operation,. or its equivalent subroutine, in the s.eqtience of operations composing a routine. 2. Number iden­tifying each step in a program stated in symbolic code. ( ,ap: ;:,'ra·sh;:,n ,nam·bor} . . ·

operation part [cOMPUT SCI] Tliat portion of a digital com­puter instruction which is reserved for the operation· cod<;>. { ,ap·;:,'ra·sh;:,n ,part }

operation process chart. [IND ENG] A graphic ~;epresenta: · iion that gives an overall yiew of an entire process, including

1.1