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1、1 11.1 Electrical Network and Basic Elements1.2 Electrical Engineering1.3 Kirchhoffs Circuit Laws1.4 Three-Phase Circuit1.5 Electromagnetic FieldPart 1 Fundaments of Electric Circuit2 21.1.1语言现象1专业英语(SpecifiedEnglish)概述随着科学技术的迅猛发展，新技术、新学科、新材料、新工艺的不断出现，各层次技术交流的日益频繁，用英语撰写的科技文献大量出现。20世纪70年代以来科技英语在教育领域逐
2、渐成为一种专业，对科技英语的研究也在不断深入，在科技翻译方面出版了大量的论文、专著，以探讨其翻译理论和翻译方法。1.1ElectricalNetworkandBasicElements3 3什么是科技英语？它和公共英语之间有哪些区别与联系呢？科技英语是指科技文体，包括英语科技论文、科技报告、科普文章、科技新闻和科技产品说明书等与科技有关的各种文献，它有别于一般英语和文学英语，对科技文体的翻译也有别于其他文体的翻译。要搞好科技英语翻译就要了解科技英语的词汇、语法、句法和特征，熟悉科技英语的思维翻译过程，掌握科技英语的翻译原则和标准，懂得科技英语的翻译技巧，学习有关的专业知识，打好扎实的功底。4
3、4科学技术是由许多专业构成的，每一个专业涉及的词汇又有一定的不同。为了掌握科技英语的一般规律，从某一个、某一类专业英语的规律认识起，不失为一种从特殊到一般的解决问题的思维方式。经过公共英语的学习后，我们基本掌握了英语的常用语法，并具有4000以上的词汇量，具备了一定的英语基础。进入高年级后，随着专业课的进一步学习，学生的专业知识技能也开始逐渐加强。5 56 6尽管很多人在此之前已经进行了多年的公共英语学习，但专业英语的学习仍是很必要的。首先，专业英语在词义上具有不同于公共英语的特点和含义，如下例：Providedyoufulfillthetermsofthecredit,wewillaccep
4、tandpayatmaturitythedraftpresentedtousunderthiscredit.错误译法：在贵公司履行信用条款的条件下，我行将接受并于成熟之日支付信用证下提示的汇票。正确译法：我们行承兑并与期满时支付信用证项下提示的汇票。句中的accept和maturity的常用意义分别为“接受”和“成熟”，而在此处，accept意为“承兑，7 7即远期汇票的付款人接受汇票，正式确认如期支付汇票金额的责任”；maturity意为“(票据的)到期”。两处错误显然是因为忽略了这两个词在专业英语中的特别意义。通过以上的例子，我们不难认识到专业词汇的一些特点，即同一个词在日常生活中，在不同
5、的专业中可能会有截然不同的含义。例如bus这个词，在日常生活中是“公共汽车”的意思，但在计算机中是指“总线”，在电力系统中是指“母线”。单靠日常用语进行望文生义的判断不仅会闹笑话，还有可能出事故。如：8 8Ifamouseisinstalledinacomputer,theavailablememoryspacewillreduce.应译为：若接上鼠标，可利用的存储空间将减小。其次，外文科技文章在结构上也具有很多自身的特点，如长句多、被动语态多、名词化结构多等，这都给对原文的理解和翻译带来了难以解决的困难。如：Itmaybetheinductorvoltageratherthanthecurr
6、entinthevariableofinterestinthecircuit.应译为：在该电路中关心的变量是电感电压而不是电流。9 910 10专业翻译是指把科技文章由原作语言(sourcelanguage)用译文语言(targetlanguage)忠实、准确、严谨、通顺、完整地再现出来的一种语言活动。它要求翻译者在具有一定专业基础知识和英语技能的前提下，借助于合适的英汉科技字典来完成整个翻译过程。专业翻译直接应用于科技和工程，因而对翻译的质量具有一定的要求。翻译上的失之毫厘，工程中就有可能差之千里，造成巨大的损失。例如，有这样一个标志牌：ControlCenter,SmokingFree.1
7、1 11它的意思是“控制中心，严禁吸烟”，free在这里作“免除的”讲；而如果理解为“随便的，自由的”，就会产生完全相反的意义。想翻译出一篇好的科技文体的文章来，并不是一件容易的事。仅仅依靠对英语的掌握或对汉语的文字驾驭能力，都不能搞好科技翻译。因为科技翻译是一个复杂的过程，涉及多方面的素质，必须综合各方面的因素。第一，必须具备科学严谨的态度。历数翻译界的专家学者所从事的翻译事业，可以看出他们付出了艰辛劳动，耗费了很多精力，进行了大量实践，12 1213 13第三，必须具备熟练地驾驭汉语的能力。同样，没有熟练地驾驭汉语语言的能力，即使理解得很透彻，翻译出来的文字不是晦涩难懂，就是语义模糊，让人
8、似懂非懂。第四，必须具备广博的专业及相关领域的知识。当今科技发展迅速，学科之间交叉渗透普遍，一个领域里会有另外领域的知识。因此，只有经常学习本专业和相关专业的知识，才能胜任科技翻译的工作。第五，必须具备必要的英语翻译理论和技巧。理论是指导实践的有效工具，有时一个段落、一个句子或一个术语，尽管了然于心，14 1415 152常见公式及符号的表达和译法在专业英语中，数词出现的频率很高，对数词的翻译及读法的掌握程度会影响对专业的学习、研究及交流。现分别介绍一些专业英语中常用的数词的译法和数学符号、公式的读法。1)基数词的表达和译法从1到12是单个单词。如，11读做eleven；12读做twelve。
9、从13到19加后缀-teen。如，13读做thirteen；19读做nineteen。16 16从20到90加后缀-ty。如，20读做twenty；23读做twenty-three；90读做ninety。百位数以上需连起来。如，500读做fivehundred；561读做fivehundred(and)sixty-one；5,661读做fivethousandsixhundred(and)sixty-one。2)序数词的表达和译法序数词翻译时加“第”。如twelfth：12th，第十二；thirtieth：30th，第三十。3)数词的增加和减少的表达和译法例：Theoxygenatomisne
10、arly16timesheavierthanthehydrogenatom.17 1718 18今年空调的产量增加2倍(增加到3倍)(如果句中three用n表示，那么常译成“增加了n-1倍或增加到n倍”)。Theproductionofair-conditionershasincreasedbythreetimesoverthepreviousyear.今年空调的产量比上一年增加了3倍。Theproductionofair-conditionershasdecreasedbythreetimesoverthepreviousyear.今年空调的产量是去年的1/3。Theproductionof
11、air-conditionershasincreasedtothreetimesthisyear.今年空调的产量增加到了3倍。19 19Theproductionofair-conditionershasincreasedbyafactorofthreetimesthisyear.今年空调的产量增加2倍。如果句中three用n表示，那么常译成“增加了n-1倍”。类似减少的译法如：reduceby10%：减少了10%；reduceto10%：减少到10%；reducebyafactorof10：减少了9/10(减少到1/10)；reduce10times：减少到1/10(减少了9/10)。4)分
12、数、小数、时间的表达和译法简单的分数容易表达。如：1/7，oneseventh；3/4，threequarters；1/4，a/onequarter；1/2，a/onehalf；，fourandahalf；，threeandfour-fifths。2020复杂的分数，表达亦有一定的规律。如：24/9，twenty-fourovernine；20/83，twentyovereightythree(twentyeighty-thirds)；7/20，seventwentieths；67/200，sixty-seventwohundredths。小数容易表达。如：0.124，(nought)poin
13、tonetwofour；0.24，(nought)pointtwofour；0.4(nought)pointfour；16.789，onesixpointseveneightnine。21 21时间或其他，表达时有一定的规律。如，60年代初期：intheearlysixties；本世纪90年代：intheninetiesofthecentury；20世纪90年代(1990s，1990s)：nineteennineties；2005年10月10日：October10th,2005(10thOctober,2005/October10,2005/10October2005)；Fig.7：图7(直译
14、)；1459.38：十四分五十九点三八秒，fourteenminutesfifty-ninepointthirtyeightseconds。5)数学符号、公式的表达和译法常见的有：2222+加(上)plus，positive，and-减(去)minus，negative乘以times，multipliedby除以dividedby，above=等于beequalto/equals/be大约等于isapproximatelyequalto()圆括号roundbrackets/parentheses方括号squaredbrackets/斜杠slash65%百分之六十五65percent232324
15、24大于或等于ismorethanorequalto小于或等于islessthanorequalto大于ismorethandeltaPhiomegaepsilon与成比例variesas/isproportionaltoomega5mm5毫米5millimetersxxapproachestoinfinity25251.1.2SpecifiedEnglishWordselectricaldevice电气设备；电气元件；电气装置conductinglead引线体，导线端resistorn.电阻器resistancen.抵抗；抵抗力；反抗；电阻；阻力inductorn.授职者；圣职授予的人；感应
16、器；电感器capacitorn.电容器capacitancen.电容；电流容量passiveelements无源元件activeelements有源元件2626circuitdiagram电路图powern.能力；力量；功率；幂；势力；政权vt.激励sinen.正弦time-variable时变的coilvt.盘绕，把卷成圈n.卷；线圈vi.成圈状transformersn.变压器dielectricadj.非传导性的；诱电性的n.电介质；绝缘体mechanismn.机械装置；机制；技巧；原理，途径；进程272728281.1.3TextElectrical Network and Basic
17、 ElementsAcircuit(electricalnetwork)isaninterconnectionofelectricalelementssuchasresistors,inductors,capacitors,transmissionlines,voltagesources,currentsourcesandswitches.Anelectricalcircuitisaspecialtypeofnetwork,onethathasaclosedloopgivingareturnpathforthecurrent.Electricalnetworksthatconsistonlyo
18、fsources(voltageorcurrent),linearlumpedelements(resistors,capacitors,inductors),andlineardistributedelements(transmissionlines)canbeanalyzedbyalgebraicandtransformmethodstodetermineDCresponse,ACresponse,andtransientresponse.2929Anactivenetworkisanetworkthatconsistsofatleastoneactivesourcelikeavoltag
19、esourceorcurrentsource.Apassivenetworkisanetworkwhichdoesnotcontainanyactivedevice.Alinearcircuitisacircuitwhichiscomposedentirelyofindependentsources,lineardependentsourcesandlinearpassiveelementsoracombinationofthese.Otherwiseitiscalledasnon-linearnetwork.Sourcescanbeclassifiedasindependentsources
20、anddependentsources.303031 31Thus,theratioofthevoltageappliedacrossaresistorsterminalstotheintensityofcurrentthroughthecircuitiscalledresistance.Resistorsarecommonelementsofelectricalnetworksandelectroniccircuitsandareubiquitousinelectronicequipment.Practicalresistorscanbemadeofvariouscompoundsandfi
21、lms,aswellasresistancewire(wiremadeofahigh-resistivityalloy,suchasnickel-chrome).Resistorsarealsoimplementedwithinintegratedcircuits,particularlyanalogdevices,andcanalsobeintegratedintohybridandprintedcircuits.3232Theelectricalfunctionalityofaresistorisspecifiedbyitsresistance:commoncommercialresist
22、orsaremanufacturedoverarangeofmorethannineordersofmagnitude.Whenspecifyingthatresistanceinanelectronicdesign,therequiredprecisionoftheresistancemayrequireattentiontothemanufacturingtoleranceofthechosenresistor,accordingtoitsspecificapplication.Thetemperaturecoefficientoftheresistancemayalsobeofconce
23、rninsomeprecisionapplications.3333Practicalresistorsarealsospecifiedashavingamaximumpowerratingwhichmustexceedtheanticipatedpowerdissipationofthatresistorinaparticularcircuit:thisismainlyofconcerninpowerelectronicsapplications.Resistorswithhigherpowerratingsarephysicallylargerandmayrequireheatsinks.
24、Inahigh-voltagecircuit,attentionmustsometimesbepaidtotheratedmaximumworkingvoltageoftheresistor.3434A1lelectricaldevicesthatconsumeenergymusthavearesistor(alsocalledaresistance)intheircircuitmodel.Inductorsandcapacitorsmaystoreenergybutovertimereturnthatenergytothesourceortoanothercircuitelement.Pow
25、erintheresistor,givenby,isalwayspositive.Energyisthendeterminedastheintegraloftheinstantaneouspower(1-1-1)3535Aninductor(alsochoke,coilorreactor)isapassivetwo-terminalelectricalcomponentthatstoresenergyinitsmagneticfield.Forcomparison,acapacitorstoresenergyinanelectricfield,andaresistordoesnotstoree
26、nergybutratherdissipatesenergyasheat.Anyconductorhasinductance.Aninductoristypicallymadeofawireorotherconductorwoundintoacoil,toincreasethemagneticfield.3636Whenthecurrentflowingthroughaninductorchanges,creatingatime-varyingmagneticfieldinsidethecoil,avoltageisinduced,accordingtoFaradayslawofelectro
27、magneticinduction,whichbyLenzslawopposesthechangeincurrentthatcreatedit.Inductorsareoneofthebasiccomponentsusedinelectronicswherecurrentandvoltagechangewithtime,duetotheabilityofinductorstodelayandreshapealternatingcurrents.Thecircuitelementthatstoresenergyinamagneticfieldisaninductor(alsocalledanin
28、ductance).3737Withtime-variablecurrent，theenergyisgenerallystoredduringsomepartsofthecycleandthenreturnedtothesourceduringothers.Whentheinductanceisremovedfromthesource,themagneticfieldwillcollapse;inotherwords,noenergyisstoredwithoutaconnectedsource.Coilsfoundinelectricmotors,transformers,andsimila
29、rdevicescanbeexpectedtohaveinductancesintheircircuitmodels.Evenasetofparallelconductorsexhibitsinductancethatmustbeconsideredatmostfrequencies.Thepowerandenergyrelationshipsareasfollows.3838(1-1-2)(1-1-3)Energystoredinthemagneticfieldofaninductanceis.3939Acapacitor(originallyknownascondenser)isapass
30、ivetwo-terminalelectricalcomponentusedtostoreenergyinanelectricfield.Theformsofpracticalcapacitorsvarywidely,butallcontainatleasttwoelectricalconductorsseparatedbyadielectric(insulator);forexample,onecommonconstructionconsistsofmetalfoilsseparatedbyathinlayerofinsulatingfilm.Capacitorsarewidelyuseda
31、spartsofelectricalcircuitsinmanycommonelectricaldevices.4040Whenthereisapotentialdifference(voltage)acrosstheconductors,astaticelectricfielddevelopsacrossthedielectric,causingpositivechargetocollectononeplateandnegativechargeontheotherplate.Energyisstoredintheelectrostaticfield.Anidealcapacitorischa
32、racterizedbyasingleconstantvalue,capacitance,measuredinfarads.Thisistheratiooftheelectricchargeoneachconductortothepotentialdifferencebetweenthem.Thecapacitanceisgreatestwhenthereisanarrowseparationbetweenlargeareasofconductor,41 41hencecapacitorconductorsareoftencalled“plates”,referringtoanearlymea
33、nsofconstruction.Inpractice,thedielectricbetweentheplatespassesasmallamountofleakagecurrentandalsohasanelectricfieldstrengthlimit,resultinginabreakdownvoltage,whiletheconductorsandleadsintroduceanundesiredinductanceandresistance.Capacitorsarewidelyusedinelectroniccircuitsforblockingdirectcurrentwhil
34、eallowingalternatingcurrenttopass,infilternetworks,forsmoothingtheoutputofpowersupplies,4242intheresonantcircuitsthattuneradiostoparticularfrequencies,inelectricpowertransmissionsystemsforstabilizingvoltageandpowerflow,andformanyotherpurposes.Whenthevoltageisvariableoveracycle,energywillbestoredduri
35、ngonepartofthecycleandreturnedinthenext.Whileaninductancecannotretainenergyafterremovalofthesourcebecausethemagneticfieldcollapses,thecapacitorretainsthechargeandtheelectricfieldcanremainafterthesourceisremoved.Thischargedconditioncanremainuntiladischargepathisprovided，4343atwhichtimetheenergyisrele
36、ased.Thecharge,qCv,onacapacitorresultsinanelectricfieldinthedielectricwhichisthemechanismoftheenergystorage.Inthesimpleparallel-platecapacitorthereisanexcessofchargeononeplateandadeficiencyontheother.Itistheequalizationofthesechargesthattakesplacewhenthecapacitorisdischarged.Thepowerandenergyrelatio
37、nshipsforthecapacitanceareasfollows.(1-1-4)4444(1-1-5)Theenergystoredintheelectricfieldofcapacitanceis.Intheanalysisofthecircuit,everycircuitdiagramcanbeconstructedinavarietyofwayswhichmaylookdifferentbutareinfactidentical.Thediagrampresentedinaproblemmaynotsuggestthebestofseveralmethodsofsolution.4
38、545Consequently,adiagramshouldbeexaminedbeforeasolutionisstartedandredrawnifnecessarytoshowmoreclearlyhowtheelementsareinterconnectedAnextremeexampleisillustratedinFig.1.1,wherethethreecircuitsareactuallyidentical.InFig.1.1(a)thethree“junctions”labeledAareshownastwo“junctions”in(b).However,resistorR
39、4isbypassedbyashortcircuitandmayberemovedforpurposesofanalysis.Then,inFig1.1(c)thesinglejunctionAisshownwithitsthreemeetingbranches.4646Fig.1.1examplethatthethreecircuitsareactuallyidenticalAnumberofelectricallawsapplytoallelectricalnetworks.Theseinclude:Kirchhoffscurrentlaw:Thesumofallcurrentsenter
40、inganodeisequaltothesumofallcurrentsleavingthenode.Kirchhoffsvoltagelaw:Thedirectedsumoftheelectricalpotentialdifferencesaroundaloopmustbezero.4747Ohmslaw:Thevoltageacrossaresistorisequaltotheproductoftheresistanceandthecurrentflowingthroughit.Nortonstheorem:Anynetworkofvoltageorcurrentsourcesandres
41、istorsiselectricallyequivalenttoanidealcurrentsourceinparallelwithasingleresistor.Theveninstheorem:Anynetworkofvoltageorcurrentsourcesandresistorsiselectricallyequivalenttoasinglevoltagesourceinserieswithasingleresistor.4848Fig.1.1examplethatthethreecircuitsareactuallyidentical4949 Notes1A1lelectric
42、aldevicesthatconsumeenergymusthavearesistor(alsocalledaresistance)intheircircuitmodel.所有耗能的仪器在其电路模型中都有电阻器(也称为电阻)。2Thecharge,q=Cv,onacapacitorresultsinanelectricfieldinthedielectricwhichisthemechanismoftheenergystorage.5050电容器中的电荷，q=Cv，在电介质中产生电场，这便是电容器储存能量的机理。3Itistheequalizationofthesechargesthattak
43、esplacewhenthecapacitorisdischarged.当电容放电时，两极板上的电荷趋向均衡。51 511.1.4ReadingMaterialsNonlinear ResistorsThecurrentvoltagerelationshipinanelementmaybeinstantaneousbutnotnecessarilylinear.Theelementisthenmodeledasanonlinearresistor.Anexampleisafilamentlampwhichathighervoltagesdrawsproportionallylesscurren
44、t.Anotherimportantelectricaldevicemodeledasanonlinearresistorisadiode.Adiodeisatwo-terminaldevicethat,roughlyspeaking,conductselectriccurrentinonedirectionfromanodetocathode,calledforward-biasedmuchbetterthantheoppositedirection(reverse-biased).5252Thecircuitsymbolforthediodeandanexampleofitscurrent
45、-voltagecharacteristicareshowninFig.1.2.Thearrowisfromtheanodetothecathodeandindicatestheforwarddirection(i0).Asmallpositivevoltageatthediodesterminalbiasesthediodeintheforwarddirectionandcanproducealargecurrent.Anegativevoltagebiasesthediodeinthereversedirectionandproduceslittlecurrentevenatlargevo
46、ltagevalues.Anidealdiodeisacircuitmodelwhichworkslikeaperfectswitch.Its(i,v)characteristicis(1-1-6)5353Fig.1.2diodescurrent-voltagecharacteristic5454Thestaticresistanceofanonlinearresistoroperatingat(i,v),is.Itsdynamicresistanceiswhichistheinverseoftheslopeofthecurrentplottedversusvo1tage.Staticandd
47、ynamicresistancesbothdependontheoperatingpoint.Otherexamplesofnonlinearelementsaretransistorsandothersemiconductordevices,vacuumtubes,andironcoreinductorsandtransformerswhenoperatedabovetheirsaturationcurrent.Manycircuitelementsthatoperatelinearlyatlowsignallevelswillshownonlinearityathighersignalle
48、vels.5555Anexampleofthiscanbeseeninmanyaudiosystemsbyturningupthevolume.Atahighenoughvolumelevel,thetransistorsorotheramplifyingelementswillbegintooperatenonlinearlyanddistortthesound.Conversely,nonlinearelementscanbemadetooperatelinearlyifthesignalinthemislimitedtoalowlevel.Iftheinputofanon-lineard
49、evicesuchasatransistoronlyvariesinasmallrangearoundafixedvalue,thentheinput/outputrelationislinearizedaroundthisfixedvalue(usuallycalledthequiescentpoint,Q-point,orBiaspoint).Thisiscalledasmallsignalmodel.56561.1.5Homework1Pleasesumupthemainpointsofthetextinseveralsentences.2Translatethefollowingsen
50、tencesintoChinese.(1)Thecurrentinareverse-biaseddiodeissmallandapproximatelyindependentofvoltageuntilthebreakdownregionathighreversevoltagesisreached.(2)Inacircuitdiagram,ontheotherhand,aresistormightbeorientedhorizontallyorvertically,anditmightappearabove,below,ornexttotheprecedingcircuitelement.57