专业英语4044.docx
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专业英语4044.docx
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专业英语4044
40.ProgrammableControllers
Vocabulary:
archaically[]古老的,古代的,旧式的
albeit[]虽然
unsophisticated[]单纯的,纯洁的,简单的
arise[]出现,发生
comeonthescene出现
retention[]保持,保留
psychologically[]心理上地,心理学地
versed[]精通的
binary[]二进位的,二元的
switch[]转换,转变
relay[]继电器
transistor[]晶体管
fluidics[]射流技术
sheer[]纯粹的,绝对的
bulk[]大小,体积
profligate[]肆意挥霍的
facility[]设备,工具
readily[]容易地
integral[]部分
plug[]插头
interaction[]交互作用
keypad[]袖珍键盘
emit[]发出,放射
diode[]二极管
robust[]坚固的,耐用的
interference[]干扰
ladder[]梯子
Boolean[]布尔数学体系的
proprietary[]专用的,专利的
instruction[]指令说明
manual[]手册,指南
individual[]个别的,单独的
consult[]查阅,参考,考虑
interpreter[]解释程序
execution[]实行,完成,执行
subject[]课题,问题,主题
Text:
1.Generaldescription
Modernprogrammablecontrollersarenomorethanmicrocomputersusedforcontrolpropose.
Theuseofthename“programmablecontroller”(PC),ormorearchaically,“programmablelogiccontroller”(PLC),arisesbecauseprogrammablecontrollers,albeitveryunsophisticatedlogicdevices,wereavailablebeforethemicrocomputercameonthescene.Theretentionofthenameismoreacceptablepsychologicallytoengineersalreadyversedinlogiccontrol.
Previousdevicesusedbinaryswitching,justasmicrocomputersdo.Theyincorporatedsuchcomponentsasrelays,solidstate(transistor)switchesorfluidics(airflowlogic).Theywereprogrammedtousetheminimumnumberofcomponents.
Theirperformancewaslimitedbyspeedofoperation,sheerbulkandcostofcomponents.
Amicroprocessormaycontain100,000switches.Memoryforprogramsisinexpensiveandplentiful.Thelimitationsoftheearlierprogrammablecontrollers,therefore,disappear.Programsarenowbestwrittenforeaseofunderstanding,ratherthantominimizecomponent,andonewaybeasprofligatewithmemoryasonechoose.
2.Facilities
Programmablecontrollerswillusuallyhavethefollowingfacilities:
a.Controlinterfaceswhicharereadilyavailableeitherintegralwiththebasicunitorasplugsinextras.
b.SomemeansofpermanentstorageofdevelopedprogramswhichwillbeeitherRAMwithbatteryorPROM.
c.Interactionwithhumansisoftenbyasimplenumerickeypad.Readoutmaybeonasimplydisplayoflight-emittingdiodes.Afullkeyboardandmonitorcanbeusedifappropriate.
d.Theyarerobustinconstructionandwell-protectedagainstelectricalnoiseandinterference.
3.Relayladderlogic
ProgrammingmaybedoneinBASICormachinecode,butoftenprogrammablecontrollersaredesignedtouserelayladderlogic.
Relayladderlogic,asitsnamesuggests,isbaseduponrelaylogicBooleanexpressions.ProprietaryPCseachhavetheirownsetofinstructionandprogrammingmanualsforindividualPCsneedtobeconsulted.
JustasaprogramwritteninBASIChastobeconvertedintomachinecodebyaspecialprogramcalledaninterpreter,sorelayladderlogichastohaveaninterpreter.
Relayladderlogicis:
a.ashardtolearnasmachinecode.
b.slowerthanmachinecodeinexecution.
c.muchmorelimitedthanmachinecodeorBASIC.
ItissuggestthereforethatanyengineercomingnewtothesubjectshouldchoosesystemsusingBASICandmachinecoderatherthanrelayladderlogic.
41.CAD/CAM
Vocabulary:
accuracy[]精确性,正确度
evolves[](使)发展,(使)进展,(使)进化
electronics[]电子学
maturity[]成热,完备
integration[]成为整体;集成;综合;一体化
threshold[]开始,开端
envision[]想象,预想
various[]不同的,各种各样的,多方面的,多样的
draft[]草图;起草,设计
schedule[]时间表;确定时间
fabrication[]制造,生产,制作
conceptualize[]使有概念
idealize[]理想化
via[]经,通过,经由
terminal[]终点站,终端
advent[]出现,到来
stack[]堆,堆栈
tape[]带子
instantaneous[]瞬间的,即刻的,即时的
dimensional[]空间的
specify[]指定
representation[]表现,陈述,代表
diagram[]图表
stroke[]一划,(绘画等)一笔
flip[]翻转
otherwise[]另外的
manipulate[]操作,处理
issue[]发布命令
symmetrical[]对称的,均匀的
linear[]线的,直线的,线性的
detailed[]详细的,逐条的
flawless[]无瑕疵的,无缺点的
resultant[]作为结果而发生的
geometric[]几何的,几何学的
artwork[]工艺图
circuit[]电路
arrange[]解决
simulate[]模拟,模仿
validate[]使生效,确认,证实
verify[]检验,校验,查证,核实
summary[]摘要,概要
comprise[]包含,由...组成
distinct[]截然不同的,独特的
analysis[]分析,分解
kinematics[]运动学
Text:
Computer-aideddesign(CAD)andcomputer-aidedmanufacturing(CAM)usedigitalcomputers,withtheirspeedandaccuracy,astheintegratingforcethroughouttheentireprocessfromengineeringdesigntoproductmanufacture.CAD/CAMevolvesfromandbringstogethersuchtechnologiesasnumericalcontrolandcomputertechnology.Tiedtogetherbythecommonusageofdigitaldata,andfedbyacontinuousstreamofelectronicsdevelopments,numericalcontrolandthedigitalcomputerhavereachedthematuritytopermitalevelofintegrationthatbringsustothethresholdofthelong-envisionedautomaticfactory.
ThevariouscomputerizedfunctionsunderCAD/CAMfallintothreegeneralareas:
1.Design/drafting,orcomputer-aidedengineering.
2.Planning/scheduling,ormanagementinformationsystems.
3.Fabrication,ormanufacturingautomation.
AconceptualizedoridealizedCAD/CAMsystemisshowninFig.Thisshowshowtheuserinteractswiththecomputerviaagraphicsterminal,designingandcontrollingthemanufacturingprocessfromstarttofinishwithinformationstoredinashareddatabase.Withtheadventofinteractivegraphics,theproblemoftheuserenteringdataandinstructionsintothecomputerwithstacksofcodedpunchedcardsorreelsoftapswentaway.Nolongerwastheuserrequiredtobeexperiencedincomputerprogrammingandoperationtousethemachine.Withinteractivegraphics,theusercommunicateswiththecomputerindisplay-screenpictures.Noknowledgeofcomputersisrequiredtooperatethesesystems,andthecommunicationisinrealtime,whichmeansthatthecomputer'sresponsetotheuser'sinstructionsisalmostinstantaneous.InCAD/CAM,therequirementisforthesolutionofthree-dimensionalmechanicaldesignandmanufacturingproblems.Interactingwiththecomputerviakeyboardandlightpenorotherpencillikedevices,thedesignerspecifiespointsandlinesonthedisplayscreentoquicklyconstructadisplay-screendrawingormodel.Thisisinrealitytherepresentationofthediagramstoredinthecomputerdatabase.
Withastrokeofthepenorbypushingabutton,thedesignercanmove,magnify,rotate,flip,copy,orotherwisemanipulatetheentiredesignoranypartofit.Forexample,bypushingabutton,thedesignermayissueaflipcommandtoproduceamirrorimageofadisplayformodelingsymmetricalparts,oratranslatecommandmaybeusedtocreatemodelsforlinearparts.Acrosssectionmaybedefinedandthentranslatedlinearlytocreateasurfacedmodel.Inasimilarmanner,circularpartscanbeeasilymodeledwitharotatecommandinwhichacrosssectionisrotatedaboutacentralaxistomodelparts.Thereoperationstakeadvantageofthecomputer'scapabilitytorepeatdetailedoperationsquicklyandflawlessly.
Afterdesigncompletion,theresultantgeometricdatastoredinthecomputermemorymaybeusedtoproducenumericalcontrolinstructionsformakingthepartsonautomatedmachinetools,ortogeneratetheartworkanddrilltapesforautomatedprintedcircuitcardfabrication.ManyCAD/CAMsystemscannowproduceNCinstructionsautomaticallyforarrangeofdifferentparttypes.Toolpathsmaybesimulatedonthedisplayscreentovalidate,verify,andmodifytheprogrammorerapidly.
Insummary,CAD/CAMiscomprisedofdistinctfunctionalareas.TheexpertsgroupCADfunctionsintofourmajorcategories:
1.Geometricmodeling2.Engineeringanalysis3.Kinematics4.Automateddrafting
CAMtechnologyalsocentersaroundfourmajorareasorcategories:
1.Numericalcontrol2.Processplanning3.Robotics4.Factorymanagement
42.CNCandDNC
Vocabulary:
desirable[]值得要的,合意的,令人想要的,悦人心意的
confuse[]搞乱,使糊涂
essentially[]本质上,本来
dedicate[]专用于
conventional[]惯例的,常规的,传统的
facility[]设备
configuration[]构造,结构,配置
bare[]刚刚充足的;仅仅
term[]术语
conveniently[]便利地
capability[](实际)能力,性能,容量
eliminate[]消除
prototype[]原型
comparatively[]比较地,相当地
reliability[]可靠性
diagnostic[]诊断的
respective[]分别的,各自的
substantial[]坚固的,实质的
interlink[]连结
cable[]电缆
compatible[]谐调的,一致的,兼容的
necessitate[]成为必要
module[]模块
approach[]方法
definitely[]明确地,干脆地
Text:
Abriefmentionaboutcomputerizednumericalcontrol(CNC)anddirectnumericalcontrol(DNC)isdesirableatthisstage.ThisshouldnotbeconfusedwithcomputeraidedprogrammingassociatedwithNC.Thelatterisessentiallyoff-linesincetheprogramsarepreparedonthecomputerindependentoftheNCmachine.TheCNCsystemhasadedicatedcomputerinitwhichcontrolstheNCfunctions.InaconventionalNCsystem,thecontrolishardwaredandthereforeanymodificationsoradd
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