科技英語(yǔ)部分課后練習(xí)答案

Amultibillion dollarcraftcalledtheCrewExplorationVehicle CEV Page26 27 III TextOrganization PartI 1 3 PartII 4 7 PartIII 8 11 PartIV 12 14 PartV 15 18 DavidGumpandGaryHudson anentrepreneurwithfreshideas Innovativetechnology Viabilityofanewmethodforair launchingspacecraft WinmoneyfromNASAandprivateinvestors IV MultipleChoices 1 5CBAAC6 10BDCAA Page52 III Translation 3 試圖利用計(jì)算機(jī)來(lái)復(fù)制人腦活動(dòng)方式的數(shù)學(xué)家們發(fā)現(xiàn) 即使運(yùn)用最先進(jìn)的電子設(shè)備 他們也要建造一臺(tái)重1萬(wàn)公斤的計(jì)算機(jī)才行 4 結(jié)果表明 在相當(dāng)長(zhǎng)的時(shí)間內(nèi) 全球平均氣溫都是相當(dāng)穩(wěn)定的 可極小的溫度變化卻意味著環(huán)境的巨大改變 5 但是 最近發(fā)表在科學(xué)雜志的一對(duì)研究報(bào)告并沒(méi)有驗(yàn)證生物燃料的這種作用 并且 事實(shí)上 相對(duì)于要被取而代之的化石燃料來(lái)說(shuō) 生物燃料對(duì)氣候產(chǎn)生的危害是有過(guò)之而無(wú)不及 Page52 III Translation 6 盡管備受關(guān)注的是研發(fā)金屬 陶瓷 聚合物與復(fù)合材料材質(zhì)的改善 但有能力生產(chǎn) 制造可以滿足特定需求的材料現(xiàn)在也在漸漸變成現(xiàn)實(shí) 7 信息高速公路是一種電子通訊網(wǎng)絡(luò) 這一網(wǎng)絡(luò)把所有的人互相聯(lián)系起來(lái) 并可提供任意一種人們想得到的電子通訊方式 8 如果把管子裝成這個(gè)樣子 使最熱的水上升 而最冷的水流下來(lái)后返回鍋爐里去 那么 鍋爐中的熱水系統(tǒng)不用水泵就能循環(huán) 道理就在于此 Page52 III Translation 9 多種因素促使人們更加關(guān)注 垃圾的處理 這種興趣的產(chǎn)生有很多因素 包括對(duì)垃圾越來(lái)越多 垃圾填埋場(chǎng)地越來(lái)越少 焚燒垃圾造成的空氣污染越來(lái)越嚴(yán)重的擔(dān)心 及對(duì)環(huán)境保護(hù)的必要性已形成的共識(shí)等 10 無(wú)論是用作轎車(chē)和公汽的能源 還是發(fā)電作其他的什么用途 燃料電池都是無(wú)需燃燒就可將氫轉(zhuǎn)化成電能 Page52 III Translation 11 每個(gè)化學(xué)元素在周期表中都有一定的原子數(shù)和位置 可以據(jù)此來(lái)推測(cè)其特性 如何同別的元素相互作用 能形成什么樣的化合物 以及它的物理屬性 12 固體加熱到足夠溫度時(shí) 它所含的電子就會(huì)有一部分離開(kāi)固體表面而飛到周?chē)目臻g中去 這種現(xiàn)象稱(chēng)為熱電子放射 通常 電子管就利用這種現(xiàn)象產(chǎn)生自由電子 Page74 75 II AbstractCorrection Thecurrentcalibrationmethodsoftheprojectile velocitymeasurementsystemareintroduced andtheproblemandtheunreasonablenessofthesemethodsareanalyzed Basedontheprincipleofthemathematicalstatistics thecalibrationmethodisinvestigatedthatmeasurestheprojectile velocityatthesametimebythemulti groupzone blockdeviceisunbiased uniformandefficientandusestheaverageofthemeasuredvalueasthetruevalueoftheprojectile velocityatthepoint Page74 75 II AbstractCorrection Themethodadvantagesareanalyzedtoo Thecalibrationsystemoftheprojectile velocitymeasurementsystembasedonthelaserscreentargetsisestablished Theexperimentandthedataprocessprovethatthemethodisnotonlyfeasible butalsoprovidesaneffectivecalibrationmethodforquantificationally 定量 givingtheuncertaintyofmeasuringtheprojectile velocityquantitatively Page77 78 2 Translation 機(jī)械 a Aimedatthesystemconsistingofsquareplansifterandflexiblesuspenderattachedtosquareplansifter therigid flexiblecouplingdynamicmodelingandthefiniteelementsimulationareemployedtostudyit ThenonlineardynamicequationofsquareplansifterisestablishedbasedontheLagrangeequation andthekinematiccirclelawisderivedfromstabilizationcondition ByusingMSC Patran Nastran thefiniteelementmodelofsquareplansifteriscreatedandthetransientresponseanalysisisapplied Thetheoreticmodelandtheresultsoffiniteelementsimulationareverifiedbyexperimentaldate Thedynamicmodelandfiniteelementsimulationmethodpresentedinthispaperpossessanimportantreferencevalueandguidancetointensitycheckoutandstructureoptimizationofsquareplansifter Page77 78 2 Translation 機(jī)械 b Inordertoobtaintheaccurateandefficientsimulationalgorithmfordescribingtherotationofthefuzeballrotor twokindsofthefuzeballrotorarenumericallysimulatedwiththemathematicalmodelofquaternionasexamples Runge KuttamethodandGearmethodareadopted TheresultsshowthatcomparingwiththenonlinearmathematicalmodelofEulerangles themodelofquaternionoffuzeballrotorisabletoavoidthesingularitywhenthenutationangleapproaches0 or180 ThearithmeticalsolutioncanbeobtainedbyRunge KuttamethodinsteadofusingtheGearmethodwhichiscomplicatedandmoretime consumedforcalculation Page82 83 I 1 7 FTFTTFFII 1 Thatbranchofscientificanalysiswhichdealswithmotions timeandforcesiscalledmechanics 2 Staticsdealswiththeanalysisofstationarysystems i e thoseinwhichtimeisnotafactor 3 Dynamicsdealswithsystemswhichchangewithtime 4 Geometryandmechanics BytheseparationofGeometryfromMechanics thedeterminationofthemotionfromdynamicalprincipleswillbemademucheasierthanifthetwopartswereundertakenconjointly ThesetwoaspectsofdynamicswerelaterrecognizedasKinematicsandkinetics anddealwithmotionandtheforcesproducingit respectively Page82 83 5 Kinematicsisthestudyofmotion Moreparticularly kinematicsisthestudyofposition displacement rotation speed velocity andacceleration Thestudy say ofplanetaryororbitalmotionisalsoaprobleminkinematics 6 Eulerbasedhisseparationofdynamicsintokinematicsandkineticsontheassumptionthattheyshoulddealwithrigidbodies Itisthisveryimportantassumptionthatallowsthetwotobetreatedseparately 7 Althoughallrealmachinepartsareflexibletosomedegree machinesareusuallydesignedfromrelativelyrigidmaterials keepingpartdeflectionstoaminimum Therefore itiscommonpracticetoassumethatdeflectionsarenegligibleandpartsarerigid Page82 83 III a d b a c j d b e c f I g f h g i h j eIV convertmotionfamiliarvariousFurthermoresuitablecombinetechnique Page85 86 I 1 Indimensioningadrawing nominalsizeisthenumbersplacedinthedimensionlinesthatrepresentdimensionsthatareonlyapproximateanddonotrepresentanydegreesofaccuracyunlesssostatedbythedesigner 2 Inengineeringpractice apermissibledeviationfromthenominalsizeistermedastolerance 3 Ifthedimensionoftheshaftislowerthanthedimensionofthehole thentherewillbeclearance Suchafitistermedclearancefit 4 Ifthedimensionoftheshaftismorethanthatofthehole thenitistermedinterferencefit 5 Dimensionsgivenclosetolerancesmeansthatthepartmustfitproperlywithsomeotherparts Page85 86 I 6 Allowanceistheminimumclearancespaceintendedbetweenmatingpartsandrepresentstheconditionofthetightestpermissiblefit 7 Unilateraltolerancemeansthatanyvariationismadeinonlyonedirectionfromthenominalorbasicdimension Thetolerancewouldbebilateralifitvariesbothoverandunderthenominaldimension II Measurement straight volumes irregular foundation necessary instruments accuracy Page85 86 III Page85 86 IV 1 緊公差的尺寸表示該零件必須與其他零件恰當(dāng)配合 兩者所示公差必須要與設(shè)計(jì)允差 制造工藝的能力以及獲取最大利潤(rùn)的最小生產(chǎn)與轉(zhuǎn)配成本一致 2 容差有時(shí)與公差相混淆 兩者的意義是完全不同的 容差是在兩配合零件間允許的最小間隙 表示配合允許的最緊的狀態(tài) 3 單向公差允許容差與配合類(lèi)型不變化的情況下改變公差 而對(duì)雙向公差來(lái)說(shuō) 如果不改變兩個(gè)配合零件中的一個(gè)或兩個(gè)的公稱(chēng)尺寸 改變公差是不可能的 Page87 88 I 1 Standardmachinetoolsareusuallygroupedinsixbasicclasses lathes drillingmachines shapers planers millingmachines andgrindingmachines 2 Grinding Grindingisoneofthemostaccurateofallthebasicmachiningmethods Agrinderdiffersfromothermachinesinthatitusesatoolmadeofemery carborundum 金剛砂 orsimilarmaterials Thewheel madeupofmanytinycuttingpoints cutswiththeentiresurfaceareathatcomesincontactwiththematerialbeingground Grinderscutwithagrindingaction removingmaterialintheformoftinyparticles Page87 88 II 車(chē)床lathe turningmachine鉆床driller drillingmachine鏜床borer boringmachine磨床grinder grindingmachine齒輪加工機(jī)床gearcuttingmachine螺紋加工機(jī)床threadingmachine銑床miller millingmachine刨插床planer shaper拉床broacher broachingmachine電加工機(jī)床electricmachine切割機(jī)床cuttingmachineIII size blueprints removing figures indicate modification belongs stands improved Page87 88 IV 1 每一種機(jī)床都根據(jù)這樣的原理來(lái)工作 對(duì)刀具或者工件施以運(yùn)動(dòng)并使兩者相接觸 然而 每種機(jī)床在所采用的運(yùn)動(dòng)方式或所應(yīng)用的方法上 又各不相同 2 旋轉(zhuǎn)的刀具垂直于工件的表面進(jìn)行連續(xù)的切削 多刃刀具旋轉(zhuǎn)與直線進(jìn)給兩種運(yùn)動(dòng)合成后 就可以在工件上加工出滿足要求的孔 3 砂輪的表面是由許多極小的微刃 砂粒 組成 操作者通過(guò)移動(dòng)工件與砂輪表面接觸 Page91