电气专业毕业设计中英文对照翻译

本科毕业设计（论文）中英文对照翻译院（系部）电气学院专业名称电气工程及其自动化年级班级学生姓名指导老师河南理工大学毕业设计外文翻译2Chapter3DigitalElectronics3.1IntroductionAcircuitthatemploysanumericalsignalinitsoperationisclassifiedasadigitalcircuit.Computers,pocketcalculators,digitalinstruments,andnumericalcontrol(NC)equipmentarecommonapplicationsofdigitalcircuits.Practicallyunlimitedquantitiesofdigitalinformationcanbeprocessedinshortperiodsoftimeelectronically.Withoperationalspeedofprimeimportanceinelectronicstoday,digitalcircuitsareusedmorefrequently.Inthischapter,digitalcircuitapplicationsarediscussed.Therearemanytypesofdigitalcircuitsthathaveapplicationsinelectronics,includinglogiccircuits,flip-flopcircuits,countingcircuits,andmanyothers.Thefirstsectionsofthisunitdiscussthenumbersystemsthatarebasictodigitalcircuitunderstanding.TheremainderofthechapterintroducessomeofthetypesofdigitalcircuitsandexplainsBooleanalgebraasitisappliedtologiccircuits.3.2DigitalNumberSystemsThemostcommonnumbersystemusedtodayisthedecimalsystem,inwhich10digitsareusedforcounting.Thenumberofdigitsinthesystemiscalleditsbase(orradix).Thedecimalsystem，therefore，hasabaseof10.Numberingsystemshaveaplacevalue，whichreferstotheplacementofadigitwithrespecttoothersinthecountingprocess.Thelargestdigitthatcanbeusedinaspecificplaceorlocationisdeterminedbythebaseofthesystem.Inthedecimalsystemthefirstpositiontotheleftofthedecimalpointiscalledtheunitsplace.Anydigitfrom0to9canbeusedinthisplace.Whennumbervaluesgreaterthan9areused,theymustbeexpressedwithtwoormoreplaces.Thenextpositiontotheleftoftheunitsplaceinadecimalsystemisthetensplace.Thenumber99isthelargestdigitalvaluethatcanbeexpressedbytwoplacesinthedecimalsystem.Eachplaceaddedtotheleftextendsthenumbersystembyapowerof10.Anynumbercanbeexpressedasasumofweightedplacevalues.Thedecimalnumber2583,forexample,isexpressedas(2×1000)+(5×100)+(8×10)+(3×1).Thedecimalnumbersystemiscommonlyusedinourdailylives.Electronically,however,itisratherdifficulttouse.Eachdigitofabase10systemwouldrequirea河南理工大学毕业设计外文翻译3specificvalueassociatedwithit,soitwouldnotbepractical.3.2.1BinaryNumberSystemElectronicdigitalsystemsareordinarilythebinarytype，whichhas2asitsbase.Onlythenumbers0or1areusedinthebinarysystem.Electronically,thevalueof0canbeassociatedwithalow-voltagevalueornovoltage.Thenumber1canthenbeassociatedwithavoltagevaluelargerthan0.Binarysystemsthatusethesevoltagevaluesaresaidtohavepositivelogic.Negativelogic,bycomparison,hasavoltageassignedto0andnovoltagevalueassignedto1.Positivelogicisusedinthischapter.Thetwooperationalstatesofabinarysystem,1and0,arenaturalcircuitconditions.Whenacircuitisturnedofforhasnovoltageapplied，itisintheoff,or0,state.Anelectricalcircuitthathasvoltageappliedisintheon，or1,state.ByusingtransistororICs，itiselectronicallypossibletochangestatesinlessthanamicrosecond.Electronicdevicesmakeitpossibletomanipulatemillionsof0sandisinasecondandthustoprocessinformationquickly.Thebasicprinciplesofnumberingusedindecimalnumbersapplyingeneraltobinarynumbers.Thebaseofthebinarysystemis2,meaningthatonlythedigits0and1areusedtoexpressplacevalue.Thefirstplacetotheleftofthebinarypoint,orstartingpoint，representstheunits，oris,location.Placestotheleftofthebinarypointarethepowersof2.Someoftheplacevaluesinbase2are2º=1,2¹=2,2²=4,2³=8,2⁴=16,25=32,and26=64.Whenbasesotherthan10areused,thenumbersshouldhaveasubscripttoidentifythebaseused.Thenumber100₂isanexample.Thenumber100₂(read“one,zero,zero,base2”)isequivalentto4inbase10,or410.Startingwiththefirstdigittotheleftofthebinarypoint,thisnumberhasvalue(0×20)+(0×21)+(1×22).Inthismethodofconversionabinarynumbertoanequivalentdecimalnumber，writedownthebinarynumberfirst.Startingatthebinarypoint，indicatethedecimalequivalentforeachbinaryplacelocationwherea1isindicated.Foreach0inthebinarynumberleaveablankspaceorindicatea0'Addtheplacevaluesandthenrecordthedecimalequivalent.Theconversionofadecimalnumbertoabinaryequivalentisachievedbyrepetitivestepsofdivisionbythenumber2.Whenthequotientisevenwithno河南理工大学毕业设计外文翻译4remainder,a0isrecorded.Whenthequotienthasaremainder.as1isrecorded.Thedivisionprocesscontinuesuntilthequotientis0.Thebinaryequivalentconsistsoftheremaindervaluesintheorderlasttofirst.3.2.2Binary-codedDecimal(BCD)NumberSystemWhenlargenumbersareindicatedbybinarynumbers，theyaredifficulttouse.Forthisreason，theBinary-CodedDecimal(BCD)methodofcountingwasdevised.Inthissystemfourbinarydigitsareusedtorepresenteachdecimaldigit.Toillustratethisprocedure，thenumber105，isconvertedtoaBCDnumber.Inbinarynumbers，10510=10001012.ToapplytheBCDconversionprocess，thebase10numberisfirstdividedintodigitsaccordingtoplacevalues.Thenumber10510givesthedigits1-0-5.Convertingeachdigittobinarygives0001-0000-0101BCD.Decimalnumbersupto99910maybedisplayedbythisprocesswithonly12binarynumbers.ThehyphenbetweeneachgroupofdigitsisimportantwhendisplayingBCDnumbers.ThelargestdigittobedisplayedbyanygroupofBCDnumbersis9.Sixdigitsofanumber-codinggrouparenotusedatallinthissystem.Becauseofthis,theoctal(base8)andthehexadecimal(base16)systemsweredevised.Digitalcircuitsprocessnumbersinbinaryformbu