Unit-14-Electrical-Appliances.ppt

Unit14ElectricalAppliances 幻灯制作 吴岱曦 Index Pre reading14 1Text14 2Readingmaterials14 3Knowledgeabouttranslation14 4Exercises14 5课文参考译文14 6阅读材料参考译文 Pre reading Readthefollowingpassage payingattentiontothequestion 1 Whatisthebasicprincipleofarefrigerator 2 Whatisthefunctionofrefrigerantinsidearefrigerator 3 Whatfrequencyradiowavethemicrowaveovenusuallyused 14 1Text 14 1 1theRefrigerator14 1 2TheAirconditioner14 1 3TheMicrowaveOven 14 1 1theRefrigerator Thebasicideabehindarefrigeratorisverysimple Itusestheevaporationofaliquidtoabsorbheat Youprobablyknowthatwhenyouputwateronyourskinitmakesyoufeelcool Asthewaterevaporates itabsorbsheat creatingthatcoolfeeling Rubbingalcoholfeelsevencoolerbecauseitevaporatesatalowertemperature Theliquid orrefrigerant usedinarefrigeratorevaporatesatanextremelylowtemperature soitcancreatefreezingtemperaturesinsidetherefrigerator Ifyouplaceyourrefrigerator srefrigerantonyourskin definitelyNOTagoodidea itwillfreezeyourskinasitevaporates Therearefivebasicpartstoanyrefrigerator Fig14 1 CompressorHeat exchangingpipes serpentineorcoiledsetofpipesoutsidetheunitExpansionvalve Heat exchangingpipes serpentineorcoiledsetofpipesinsidetheunitRefrigerant liquidthatevaporatesinsidetherefrigeratortocreatethecoldtemperatures Manyindustrialinstallationsusepureammoniaastherefrigerant Pureammoniaevaporatesat 32degreesCelsius Fig14 1partsofrefrigerator A insidetherefrigeratorB CompressorC Expansionvalve Thebasicmechanismofarefrigeratorworkslikethis Thecompressorcompressestherefrigerantgas Thisraisestherefrigerant spressureandtemperature sotheheat exchangingcoilsoutsidetherefrigeratorallowtherefrigeranttodissipatetheheatofpressurization Asitcools therefrigerantcondensesintoliquidformandflowsthroughtheexpansionvalve Whenitflowsthroughtheexpansionvalve theliquidrefrigerantisallowedtomovefromahigh pressurezonetoalow pressurezone soitexpandsandevaporates lightblue Inevaporating itabsorbsheat makingitcold Thecoilsinsidetherefrigeratorallowtherefrigeranttoabsorbheat makingtheinsideoftherefrigeratorcold Thecyclethenrepeats Pureammoniagasishighlytoxictopeopleandwouldposeathreatiftherefrigeratorweretoleak soallhomerefrigeratorsdon tusepureammonia YoumayhaveheardofrefrigerantsknowasFreonanon toxicreplacementforammonia Ithasaboutthesameboilingpointasammonia However Freonisnottoxictohumans soitissafetouseinyourkitchen butmanylargeindustrialrefrigeratorsstilluseammonia Inthe1970s itwasdiscoveredthattheFreontheninuseareharmfultotheozonelayer soasofthe1990s allnewrefrigeratorsandairconditionersuserefrigerantsthatarelessharmfultotheozonelayer 14 1 2theAirConditioner Anairconditionerisbasicallyarefrigeratorwithouttheinsulatedbox Itusestheevaporationofarefrigerant likeFreon toprovidecooling ThemechanicsoftheFreonevaporationcyclearethesameinarefrigeratorasinanairconditioner 1 ThecompressorcompressescoolFreongas causingittobecomehot high pressureFreongas 2 Thishotgasrunsthroughasetofcoilssoitcandissipateitsheat anditcondensesintoaliquid 3 TheFreonliquidrunsthroughanexpansionvalve andintheprocessitevaporatestobecomecold low pressureFreongas 4 Thiscoldgasrunsthroughasetofcoilsthatallowthegastoabsorbheatandcooldowntheairinsidethebuilding MixedinwiththeFreonisasmallamountofalightweightoil Thisoillubricatesthecompressor MostairconditionershavetheircapacityratedinBritishthermalunits BTU Generallyspeaking aBTUistheamountofheatrequiredtoraisethetemperatureofonepound 0 45kg ofwater1degreeFahrenheit 0 56degreesCelsius Specifically 1BTUequals1 055joules Theenergyefficiencyrating EER ofanairconditionerisitsBTUratingoveritswattage Forexample ifa10 000 BTUairconditionerconsumes1 200watts itsEERis8 3 10 000BTU 1 200watts Obviously youwouldliketheEERtobeashighaspossible butnormallyahigherEERisaccompaniedbyahigherprice 14 1 3theMicrowaveOven Amicrowaveoven Fig14 2 consistsof amagnetronamagnetroncontrolcircuit usuallywithamicrocontroller awaveguideacookingchamber orcookingcavity Fig14 2amicrowaveoven Amicrowaveovenworksbypassingmicrowaveradiation usuallyatafrequencyof2 450MHz awavelengthof12 24cm throughthefood Water fat andsugarmoleculesinthefoodabsorbenergyfromthemicrowavebeaminaprocesscalleddielectricheating Mostmoleculesareelectricdipoles meaningthattheyhaveapositivechargeatoneendandanegativechargeattheother andisthereforetwistedtoandfromasittriestoalignitselfwiththealternatingelectricfieldinducedbythemicrowavebeam Thismolecularmovementcreatesheat Microwaveheatingismostefficientonliquidwater andmuchlesssoonfats sugars andfrozenwater Microwaveheatingissometimesincorrectlyexplainedasresonanceofwatermolecules butthisoccursonlyatmuchhigherfrequencies inthetensofgigahertz ThecookingchamberitselfisaFaradaycageenclosuretopreventthemicrowavesescapingintothesurroundings Theovendoorisusuallyaglasspanel buthasalayerofconductivemeshtomaintaintheshielding Sincethemeshwidthismuchlessthanthewavelengthof12cm themicrowaveradiationcannotpassthroughthedoor whilevisiblelight withamuchshorterwavelength can Microwavesareradiowaves Inthecaseofmicrowaveovens thecommonlyusedradiowavefrequencyis2 450MHz Radiowavesinthisfrequencyrangehaveaninterestingproperty theyareabsorbedbywater fatsandsugars Whentheyareabsorbedtheyareconverteddirectlyintoatomicmotion heat Microwavesinthisfrequencyrangehaveanotherinterestingproperty theyarenotabsorbedbymostplastics glassorceramics Metalreflectsmicrowaves whichiswhymetalpansdonotworkwellinamicrowaveoven Withwirelesscomputernetworksgaininginpopularity microwaveinterferencehasbecomeaconcernamongthosewithwirelessnetworks Microwaveovensarecapableofdisruptingwirelessnetworktransmissionsduetothefactthatthemicrowavecreatesradiowavesatabout2 450MHz 14 2Readingmaterials 14 2 1GasandPropaneRefrigerators14 2 2Historyaboutmicrowaveoven14 2 3VacuumCleaner14 2 4EmbeddedSystem 14 2 1GasandPropaneRefrigerators Ifyouwanttousearefrigeratorwhereelectricityisnotavailable youmayuseagasorpropane poweredrefrigerator Theserefrigeratorsareinterestingbecausetheyhavenomovingpartsandusegasorpropaneastheirprimarysourceofenergy Also theyuseheat intheformofburningpropane toproducethecoldinsidetherefrigerator Agasrefrigeratorusesammoniaasthecoolant andituseswater ammoniaandhydrogengastocreateacontinuouscyclefortheammonia Therefrigeratorhasfivemainparts Generator generatesammoniagasSeparator separatesammoniagasfromwater Condenser wherehotammoniagasiscooledandcondensedtocreateliquidammoniaEvaporator whereliquidammoniaevaporatestocreatecoldtemperaturesinsidetherefrigeratorAbsorber absorbstheammoniagasinwater Thecycleworkslikethis Heatisappliedtothegenerator Theheatcomesfromburningsomethinglikegas propaneorkerosene Inthegeneratorisasolutionofammoniaandwater Theheatraisesthetemperatureofthesolutiontotheboilingpointoftheammonia Theboilingsolutionflowstotheseparator Intheseparator thewaterseparatesfromtheammoniagas Theammoniagasflowsupwardtothecondenser Thecondenseriscomposedofmetalcoilsandfinsthatallowtheammoniagastodissipateitsheatandcondenseintoaliquid Theliquidammoniamakesitswaytotheevaporator whereitmixeswithhydrogengasandevaporates producingcoldtemperaturesinsidetherefrigerator Theammoniaandhydrogengasesflowtotheabsorber Here thewaterthathascollectedintheseparatorismixedwiththeammoniaandhydrogengases Theammoniaformsasolutionwiththewaterandreleasesthehydrogengas whichflowsbacktotheevaporator Theammonia and watersolutionflowstowardthegeneratortorepeatthecycle 14 2 2HistoryaboutMicrowaveOven TheideaforusingmicrowavestocookfoodwasdiscoveredbyPercySpencerwhowasworkingforRaytheonandwasbuildingmagnetronsforradarsets Onedayhewasworkingonanactiveradarsetwhenhehadnoticedasuddenandstrangesensation andsawthatachocolatebarhehadinhispockethadmelted Theholderof120patents Spencerwasnostrangertodiscoveryandexperiment andrealizedwhatwashappening Thefirstfoodtobedeliberatelycookedwithmicrowaveswaspopcorn andthesecondwasanegg whichexplodedinthefaceofoneoftheexperimenters In1946Raytheonpatentedthemicrowavecookingprocessandin1947 theybuiltthefirstcommercialmicrowaveoven theRadarange Itwasalmost6feet 1 8m tallandweighed750pounds 340kg Itwaswater cooledandproduced3 000watts aboutthreetimestheamountofradiationproducedbymicrowaveovenstoday Inthe1960s LittonboughtfromStudebaker FranklinManufacturingassets whichhadbeenmanufacturingmagnetrons building andsellingmicrowaveovenssimilartotheRadarange Littonthendevelopedauniqueconfigurationofthemicrowave theshort wideshapethatisnowcommon Themagnetronfeedwasalsounique ThenewovenwasshownatatradeshowinChicago andthiswasthebeginningoftherevolutionarygrowthofmicrowaveovens Anumberofothercompaniesjoinedinthemarket andforatimemostsystemswerebuiltbydefensecontractors whowerethemostfamiliarwiththemagnetron Littonwasparticularlywellknownintherestaurantbusiness Bythelate1970sthetechnologyhadimprovedtothepointwherepriceswerefallingrapidly Formerlyfoundonlyinlargeindustrialapplications microwaveswereincreasinglybecomingastandardfixtureofmostkitchens Therapidlyfallingpriceofmicroprocessorsalsohelpedbyaddingelectroniccontrolstomaketheovenseasiertouse Bythelate1980stheywerealmostuniversalandcurrentlyitisestimatedthatnearly95 ofAmericanhouseholdshaveamicrowave 14 2 3VacuumCleaner Whenyousipsodathroughastraw youareutilizingthesimplestofallsuctionmechanisms Suckingthesodaupcausesapressuredropbetweenthebottomofthestrawandthetopofthestraw Withgreaterfluidpressureatthebottomthanthetop thesodaispusheduptoyourmouth Thisisthesamebasicmechanismatworkinavacuumcleaner thoughtheexecutionisabitmorecomplicated itreliesonahostofphysicalprinciplestocleaneffectively Fig14 3TheVacuumCleaner Itmaylooklikeacomplicatedmachine buttheconventionalvacuumcleanerisactuallymadeupofonlysixessentialcomponents seeinFig14 3 Anintakeport whichmayincludeavarietyofcleaningaccessories AnexhaustportAnelectricmotorAfanAporousbagAhousingthatcontainsalltheothercomponents Whenyouplugthevacuumcleanerinandturniton thisiswhathappens Theelectriccurrentoperatesthemotor Themotorisattachedtothefan whichhasangledblades likeanairplanepropeller Asthefanbladesturn theyforceairforward towardtheexhaustport Whenairparticlesaredrivenforward thedensityofparticles andthereforetheairpressure increasesinfrontofthefananddecreasesbehindthefan Thispressuredropbehindthefanisjustlikethepressuredropinthestrawwhenyousipfromyourdrink Thepressurelevelintheareabehindthefandropsbelowthepressureleveloutsidethevacuumcleaner theambientairpressure Thiscreatessuction apartialvacuum insidethevacuumcleaner Theambientairpushesitselfintothevacuumcleanerthroughtheintakeportbecausetheairpressureinsidethevacuumcleanerislowerthanthepressureoutside Aslongasthefanisrunningandthepassagewaythroughthevacuumcleanerremainsopen thereisaconstantstreamofairmovingthroughtheintakeportandouttheexhaustport Thisstreamofairactsjustlikeastreamofwater Themovingairparticlesrubagainstanyloosedustordebrisastheymove andifthedebrisislightenoughandthesuctionisstrongenough thefrictioncarriesthematerialthroughtheinsideofthevacuumcleaner Thisisthesameprinciplethatcausesleavesandotherdebristofloatdownastream Somevacuumdesignsalsohaverotatingbrushesattheintakeport whichkickdustanddirtloosefromthecarpetsoitcanbepickedupbytheairstream Asthedirt filledairmakesitswaytotheexhaustport itpassesthroughthevacuum cleanerbag Thesebagsaremadeofporouswovenmaterial typicallyclothorpaper whichactsasanairfilter Thetinyholesinthebagarelargeenoughtoletairparticlespassby buttoosmallformostdirtparticlestofitthrough Thus whentheaircurrentstreamsintothebag alltheairmovesonthroughthematerial butthedirtanddebriscollectinthebag Youcanputthevacuum cleanerbaganywherealongthepathbetweentheintaketubeandtheexhaustport aslongastheaircurrentflowsthroughit Inuprightvacuumcleaners thebagistypicallythelaststoponthepath Immediatelyafteritisfiltered theairflowsbacktotheoutside Incanistervacuums thebagmaybepositionedbeforethefan sotheairisfilteredassoonasitentersthevacuum 14 2 4EmbeddedSystem Anembeddedsystemisaspecial purposecomputersystemdesignedtoperformoneorafewdedicatedfunctions oftenwithreal timecomputingconstraints Itisusuallyembeddedaspartofacompletedeviceincludinghardwareandmechanicalparts Incontrast ageneral purposecomputer suchasapersonalcomputer candomanydifferenttasksdependingonprogramming Embeddedsystemscontrolmanyofthecommondevicesinusetoday Sincetheembeddedsystemisdedicatedtospecifictasks designengineerscanoptimizeit reducingthesizeandcostoftheproduct orincreasingthereliabilityandperformance Someembeddedsystemsaremass produced benefitingfromeconomiesofscale Physically embeddedsystemsrangefromportabledevicessuchasdigitalwatchesandMP3players tolargestationaryinstallationsliketrafficlights factorycontrollers orthesystemscontrollingnuclearpowerplants Complexityvariesfromlow withasinglemicrocontrollerchip toveryhighwithmultipleunits peripheralsandnetworksmountedinsidealargeenclosure Ingeneral embeddedsystem isnotanexactlydefinedterm asmanysystemshavesomeelementofprogrammability Forexample Handheldcomputerssharesomeelementswithembeddedsystems suchastheoperatingsystemsandmicroprocessorswhichpowerthem butarenottrulyembeddedsystems becausetheyallowdifferentapplicationstobeloadedandperipheralstobeconnected 14 3Knowledgeabouttranslation 在一般情况下 句中的某些成分应当放在一起 如主语和谓语 动词和宾语等 但在科技英语中我们常可以看到这些成分离得较远 被其他成分隔开了 这种语言现象叫分离现象 起隔离作用的主要有 1 各种短语 介词短语 分词短语 不定式短语等 2 各种从句 3 句中的附加成分 插入语 同位语和独立成分 分析这种隔离现象可以更好地帮助我们理解整个句子的原义 常见的分离现象有 1 主谓分离2 动宾分离3 复合谓语本身的分离4 定语和被修饰名词的分离5 某些词与所要求介词的分离 1 主谓分离 Theforcethatpushesyoutowardthefrontofthebuswhenitstopsistheinertiaofyourbody 汽车停止时 推你往前倾的力就是你身体的惯性 Thekeyboard themostcommonlyusedinputdevice isintroducedinUnit14 在14单元中介绍了键盘 一种最常用的输入设备 2 动宾分离 有时作状语的介词短语等放在动词之后 用来修饰该动词 而把动词描述动作的对象 宾语隔开了 Butnaysayerspointoutthattablet stylecomputershavebeentestedwithflawsthatvendorsnowclaimtohaveovercome 但是反对者指出 平板风格的计算机以前就试验过但是有缺陷 虽然供应商声称已经克服了缺陷 overcome的宾语是that或者说flaws 3 复合谓语本身的分离 在复合谓语之间插入含有状语意义的介词短语或状语从句 使复合谓语本身产生分离现象 Manyformsofmotionarehighlycomplex buttheymayinallcasesbeconsideredasbeingmadeupoftranslationsandrotations 很多运动的形式是非常复杂的 但在所有的情况下 都可以认为是由平移和转动合成的 复合谓语maybeconsidered之间插入inallcases造成分离现象 4 定语和被修饰名词的分离 Aninsulatorisamaterialthatoffersaveryhighresistancetothepassagethroughitofanelectriccurrent 绝缘体是一种对通过它的电流产生很高阻力的材料 ofanelectriccurrent是修饰passage的定语 被throughit分隔开了 5 某些词与所要求介词的分离 Theelectricresistanceofawireistheratioofthepotentialdifferencebetweenitstwoendstothecurrentinthewire 导线的电阻等于该导线两端之间的电位差与导线中电流的比值 theratioofAtoB 为 A 与 B 之比 这里被betweenitstwoends隔开了 14 4Exercises 1 PutthePhrasesintoEnglish2 PutthePhrasesintoChinese3 Translation4 Translation 2 1 PutthePhrasesintoEnglish 1 吸热2 冰点温度3 热交换线圈4 扩张阀5 低压区 1 absorbheat2 freezingtemperatures3 heat exchangingcoils4 theexpansionvalve5 low pressurezone 单击鼠标显示答案 6 空调7 压缩冷的氟里昂气体8 磁电管控制电路9 正电荷10 糖分子 6 airconditioner7 compressescoolFreongas8 amagnetroncontrolcircuit9 positivecharge10 sugarmolecules 单击鼠标显示答案 2 PutthePhrasesintoChinese 1 thebasicideabehindarefrigerator2 creatingthatcoolfeeling3 evaporatesatalowertemperature4 liquidthatevaporatesinsidetherefrigerator5 flowthroughtheexpansionvalve 1 冰箱的基本概念 原理 2 产生冷的感觉3 在低温下蒸发4 在冰箱内部蒸发的液体5 流过扩张阀 单击鼠标显示答案 6 behighlytoxictopeople7 runthroughasetofcoils8 absorbenergyfromthemicrowavebeam9 twistedtoandfrom10 resonanceofwatermolecules 6 对人有毒性 或译容易使人中毒7 流过一组线圈 或译流过一组散热管 8 从微波束中吸收能量9 扭来扭去 或来回扭动10 水分子的共振 单击鼠标显示答案 3 Translation 1 Asthewaterevaporates itabsorbsheat creatingthatcoolfeeling 2 Ifyouplaceyourrefrigerator srefrigerantonyourskin definitelyNOTagoodidea itwillfreezeyourskinasitevaporates 1 因为水蒸发时 吸收热量 带来凉爽的感觉 2 如果你把冰箱中的制冷剂放在皮肤上 绝对不是好主意 别这样做 当它蒸发时会使皮肤结冰 单击鼠标显示答案 3 Pureammoniagasishighlytoxictopeopleandwouldposeathreatiftherefrigeratorweretoleak 4 TheFreonliquidrunsthroughanexpansionvalve andintheprocessitevaporatestobecomecold low pressureFreongas 3 纯氨气是有毒的 如果制冷液泄漏对人是一种威胁 或译是很危险的 4 氟里昂液体流过扩散阀 在这过程中蒸发成冷的低压氟里昂气体 单击鼠标显示答案 5 Microwaveheatingismostefficientonliquidwater andmuchlesssoonfats sugars andfrozenwater 6 Withwirelesscomputernetworksgaininginpopularity microwaveinterferencehasbecomeaconcernamongthosewithwirelessnetworks 5 微波加热对液态的水最有效 对脂肪 糖 结冰的水加热效果就差一些 6 随着无线计算机网络日益普及 微波干扰已成为无线网络工作中值得关注的问题 单击鼠标显示答案 7 Thefirstfoodtobedeliberatelycookedwithmicrowaveswaspopcorn andthesecondwasanegg whichexplodedinthefaceofoneoftheexperimenters 8 Bythelate1970sthetechnologyhadimprovedtothepointwherepriceswerefallingrapidly 7 第一种故意用微波去加热的食品是爆玉米 第二种食品是鸡蛋 鸡蛋在一个实验者面前炸开了 8 到1970年后期 技术已得到很大的改进 价格迅速下降 单击鼠标显示答案 9 Itmaylooklikeacomplicatedmachine buttheconventionalvacuumcleanerisactuallymadeupofonlysixessentialcomponents 10 Youcanputthevacuum cleanerbaganywherealongthepathbetweentheintaketubeandtheexhaustport aslongastheaircurrentflowsthroughit 9 真空吸尘器也许看起来像一个复杂的机器 但传统的真空吸尘器实际上仅由六个基本部件组成 10 可以把真空吸尘器的垃圾袋放在进风口和排气口之间任何地方 只要空气流可以经过袋子 单击鼠标显示答案 4 Translation 2 Afirewallisaprotectivesystemthatlies inessence betweenyourcomputernetworkandtheInternet Whenusedcorrectly afirewallpreventsunauthorizeduseandaccesstoyournetwork 防火墙本质上是你的计算机网络和互联网之间的一个保护系统 如果正确运用的话 防火墙可以阻止任何未授权的使用和访问你的计算机网络 单击鼠标显示答案 Thejobofafirewallistocarefullyanalyzedataenteringandexitingthenetworkbasedonyourconfiguration Itignoresinformationthatcomesfromanunsecured unknownorsuspiciouslocations 防火墙的任务是根据你的设置仔细分析流入和流出网络的数据 它 忽视 不允许来自不可靠的 不知或值得怀疑的地址的信息进入 你的计算机 单击鼠标显示答案 Afirewallplaysanimportantroleonanynetworkasitprovidesaprotectivebarrieragainstmostformsofattackcomingfromtheoutsideworld 防火墙在任何网络中都起到一个重要的作用 因为它对来自外部世界的各种侵袭起到保护和屏障的作用 单击鼠标显示答案 14 5课文参考译文 14 5 1冰箱14 5 2空调14 5 3微波炉 14 5 1冰箱 冰箱的基本原理十分简单 用液体的蒸发来吸收热量 也许你知道当皮肤上有水时会感到凉快 这是因为水蒸发时 会吸收热量带来凉爽的感觉 如果擦酒精你会感到更凉爽 因为酒精的蒸发温度更低 冰箱中所用的液体或称制冷剂的蒸发温度特别低 所以可以在冰箱中产生冰冻的温度 如果你把冰箱中的制冷剂放在皮肤上 绝对不是好主意 别这样做 当它蒸发时会使皮肤结冰 冰箱由五个基本部分组成 见图14 1 压缩机热交换管 箱外的一组蜿蜒盘绕的管子扩散阀热交换管 箱内的一组蜿蜒盘绕的管子制冷剂 在冰箱中蒸发以获得低温的液体 很多工业冰箱用纯氨作为制冷剂 纯氨的蒸发温度在 32 冰箱的基本工作原理如下 压缩机压缩制冷剂气体 使制冷剂的压力和温度升高 冰箱外面的热交换管使制冷剂散热 当制冷剂冷却后 收缩成液态 流过扩散阀 流过扩散阀时 液态制冷剂从高压管中流入低压管中 制冷剂膨胀蒸发成为 淡蓝色 气体 在蒸发过程中制冷剂要吸收热量 使变成冷的气体 冰箱内部的管子使制冷剂从冰箱中吸收热量 使冰箱内部变冷 如此反复循环 纯氨气是有毒的 如果纯氨制冷剂泄漏对人是一种威胁 所以家用冰箱不用纯氨 你可能听说过Freon 氟里昂 一种氨的无毒替代品 与氨有基本相同的沸点 但氟里昂对人是没有毒的 所以可以安全地在厨房中使用 但许多大的工业冰箱仍用纯氨作制冷剂 在 20世纪 70年代 发现当时所用的氟里昂破坏臭氧层 因此 到90年代 所有的冰箱和空调采用新制冷剂以减少对臭氧层的破坏作用 14 5 2空调 空调是没有隔热箱的冰箱 它利用制冷剂如氟里昂的蒸