第2章信息與通信工程專業(yè)英語(第2版)-韓定定

第2章ApplicationandAppreciation★

LessonOne

ModernDigitalDesign&DigitalSignalProcessing★L(fēng)essonTwo EmbeddedSystemsandApplications★L(fēng)essonThree

VirtualInstruments★L(fēng)essonFour

DesignPatterns第2章ApplicationandAppreciation★

LessonFive

DigitalImageProcessing&VideoCompression★

LessonSix

TechnologyofModernCommunication★

LessonSeven

WirelessSensorNetworks

★

LessonEight

Cryptology第2章ApplicationandAppreciation★

LessonNine

ComplexNetworksandItsApplications★

LessonTen CloudComputingLessonOne

ModernDigitalDesign&Digital

SignalProcessing＊TextA:IntroductiontoDigitalSignalProcessing＊TextB:ModernDigitalDesignLessonOne

ModernDigitalDesign&Digital

SignalProcessing

TextA

IntroductiontoDigitalSignalProcessing

DigitalSignalProcessingisoneofthemostpowerfultechnologies….EachoftheseareashasdevelopedadeepDSPtechnology,withitsownalgorithms,mathematics,andspecializedtechniques.ThiscombinationofbreathanddepthmakesitimpossibleforanyindividualtomasteralloftheDSPtechnologythathasbeendeveloped.…andlearningspecializedtechniquesforyourparticularareaofinterest.每個研究領(lǐng)域都在它自身特有的算法、數(shù)學(xué)和技術(shù)的基礎(chǔ)上更深入地開發(fā)DSP技術(shù)，從而使DSP技術(shù)在廣度和深度兩個方面都得到拓展，因此，任何人都不可能掌握所有現(xiàn)存的DSP技術(shù)。LessonOne

ModernDigitalDesign&Digital

SignalProcessing

TextA

IntroductiontoDigitalSignalProcessing

Thedevelopmentofdigitalsignalprocessingdatesfromthe1960'swiththeuseofmainframedigitalcomputersfornumber-crunchingapplicationssuchastheFastFourierTransform(FFT),whichallowsthefrequencyspectrumofasignaltobecomputedrapidly.Thesetechniqueswerenotwidelyusedatthattime,becausesuitablecomputingequipmentwasgenerallyavailableonlyinuniversitiesandotherscientificresearchinstitutions.數(shù)字信號處理技術(shù)源于20世紀(jì)60年代，彼時，大型計(jì)算機(jī)開始用于處理計(jì)算量較大的運(yùn)算，例如可以快速獲得信號的頻譜的快速傅立葉變換（FFT）等。在本句中，Thedevelopmentofdigitalsignalprocessing是主語，datesfrom是謂語，意思是起源于歷史上的某一個年代。后面以which引導(dǎo)的定語從句用于修飾FFT。LessonOne

ModernDigitalDesign&Digital

SignalProcessing

TextA

IntroductiontoDigitalSignalProcessing

Thistechnologicalrevolutionoccurredfromthetop-down.…Whilestilltherealmofelectricalengineering,nearlyeveryscientistandengineerhassomebackgroundinbasiccircuitdesign.Withoutit,theywouldbelostinthetechnologicalworld.DSPhasthesamefuture.DSPhasrevolutionizedmanyareasinscienceandengineering.AfewofthesediverseapplicationsareshowninFigure1.沒有基本的電路設(shè)計(jì)的背景（經(jīng)驗(yàn)），他們將會被技術(shù)界淘汰。it是指前一句中的somebackgroundinbasiccircuitdesign。lost的原意是丟失,這里意譯為“淘汰”。LessonOne

ModernDigitalDesign&Digital

SignalProcessing

TextA

IntroductiontoDigitalSignalProcessing

Theintroductionofthemicroprocessorinthelate1970'sandearly1980'smadeitpossibleforDSPtechniquestobeusedinamuchwiderrangeofapplications.…(NotethattheacronymDSPcanvariouslymeanDigitalSignalProcessing,thetermusedforawiderangeoftechniquesforprocessingsignalsdigitally,orDigitalSignalProcessor,aspecializedtypeofmicroprocessorchip).

…需要注意的是，縮寫DSP有多種含義，它既可以解釋為“數(shù)字信號處理”，也可以解釋為“數(shù)字信號處理器”，前者表示一種目前被廣泛采用的數(shù)字信號處理技術(shù)，后者則表示一種專用的微處理器芯片。LessonOne

ModernDigitalDesign&Digital

SignalProcessing

TextA

IntroductiontoDigitalSignalProcessing

Thereareapproximatelyonebilliontelephonesintheworld.Atthepressofafewbuttons,switchingnetworksallowanyoneofthesetobeconnectedtoanyotherinonlyafewseconds.…Incomparison,DSPconvertsaudiosignalsintoastreamofserialdigitaldata.Sincebitscanbeeasilyintertwinedandlaterseparated,manytelephoneconversationscanbetransmittedonasinglechannel.Thistechnologyiscalledmultiplexing.比較而言，DSP可以將音頻信號轉(zhuǎn)變?yōu)閿?shù)據(jù)流。由于數(shù)字比特易于組合與分離，因此，多路電話信號可以通過一條信道實(shí)現(xiàn)傳輸，這種技術(shù)稱為復(fù)用。LessonOne

ModernDigitalDesign&Digital

SignalProcessing

TextA

IntroductiontoDigitalSignalProcessing

Whenavoicesignalisdigitizedat8000samples/sec,mostofthedigitalinformationisredundant.Thatis,theinformationcarriedbyanyonesampleislargelyduplicatedbytheneighboringsamples.DozensofDSPalgorithmshavebeendevelopedtoconvertdigitizedvoicesignalsintodatastreamsthatrequirefewerbits/sec.Thesearecalleddatacompressionalgorithms.…當(dāng)對話音信號在8000次/秒的采樣率基礎(chǔ)上進(jìn)行編碼時，獲得的數(shù)字信號存在冗余，也就是說，某一采樣點(diǎn)的信息在很大程度上與其它采樣點(diǎn)的信息重復(fù)。LessonOne

ModernDigitalDesign&Digital

SignalProcessing

TextA

IntroductiontoDigitalSignalProcessing

NewWordsandExpressionsalgorithmn.算法sonar

n.

聲納

，聲波定位儀ECG=Electrocardiograph

心電圖FourierTransform

傅立葉變換programmable

adj.可編程的multiplexing

多路復(fù)用技術(shù)amplifier

n.放大器transducern.傳感器，變頻器LessonOne

ModernDigitalDesign&Digital

SignalProcessing

TextA

IntroductiontoDigitalSignalProcessing

uncompression

解壓縮digitalrecording

數(shù)字式錄音featureextraction特征抽取reproductionn.再現(xiàn)，再生electroden.電極noisen.噪聲mainssupply交流電源electronicvoicemail語音郵件LessonOne

ModernDigitalDesign&Digital

SignalProcessing

TextA

IntroductiontoDigitalSignalProcessing

HilbertTransform

希爾伯特變換redundantadj.多余的，冗余的filteringn.濾波datacompression數(shù)據(jù)壓縮artificialreverberation人工混響vocaltractsimulation

聲音模擬器speechgeneration語音產(chǎn)生featurematching特征匹配LessonOne

ModernDigitalDesign&Digital

SignalProcessing

TextB

ModernDigitalDesign

Thespeedoflightisjusttooslow.…Thesesystemsoperateathighfrequenciesatwhichconductorsnoongerbehaveassimplewires,butinsteadexhibithigh-frequencyeffectsandbehaveastransmissionlinesthatareusedtotransmitorreceiveelectricalsignalstoorfromneighboringcomponents.Ifthesetransmissionlinesarenothandledproperly,theycanunintentionallyruinsystemtiming.…當(dāng)系統(tǒng)工作于高頻段時，導(dǎo)體不再是簡單的導(dǎo)線，此時，導(dǎo)體將具表現(xiàn)出高頻特性，即具有傳輸線的功能和特性，該特性使得導(dǎo)體能與相鄰器件之間實(shí)現(xiàn)信號的發(fā)送和接收。transmitto和receivefrom是固定搭配。LessonOne

ModernDigitalDesign&Digital

SignalProcessing

TextB

ModernDigitalDesign

Asthereaderundoubtedlyknows,thebasicideaindigitaldesignistocommunicateinformationwithsignalsrepresenting1sor0s.…Fromthesystemdesignerspointofview,thereareusuallyhigh-andlow-voltagethresholds,knownasVihandVil,associatedwiththereceivingsilicon,abovewhichandbelowwhichahighorlowvaluecanbeguaranteedtobereceivedunderallconditions.…從系統(tǒng)設(shè)計(jì)者的角度來說，高電壓門限（Vih）和低電壓門限（Vil）的取值與硅的品質(zhì)有關(guān)，在任何條件下，高于Vih的值或低于Vil的值都可以保證被正確接收。fromone’spointofview:從某人的角度來看，從某人的觀點(diǎn)來看。LessonOne

ModernDigitalDesign&Digital

SignalProcessing

TextB

ModernDigitalDesign

Inordertomaximizethespeedofoperationofadigitalsystem,…Everyconductorhasacapacitance,inductance,andfrequency-dependentresistance.Atahighenoughfrequency,noneofthesethingsisnegligible.Thusawireisnolongerawirebutadistributedparasiticelementthatwillhavedelayandatransientimpedanceprofilethatcancausedistortionsandglitchestomanifestthemselvesonthewaveformpropagatingfromthedrivingchiptothereceivingchip.每個導(dǎo)體都有電容和電感，他們的阻抗因頻譜而變。當(dāng)頻率足夠高時，必須要考慮這些因素的影響，此時，導(dǎo)線不再僅僅是簡單的導(dǎo)線，而是分布參數(shù)元件，這樣的元件會帶來延時和瞬變阻抗，從而導(dǎo)致驅(qū)動芯片和接收芯片之間傳輸?shù)牟ㄐ伟l(fā)生畸變。LessonOne

ModernDigitalDesign&Digital

SignalProcessing

TextB

ModernDigitalDesign

Thewireisnowanelementthatiscoupledtoeverythingaroundit,includingpowerandgroundstructuresandothertraces.Thesignalisnotcontainedentirelyintheconductoritselfbutisacombinationofallthelocalelectricandmagneticfieldsaroundtheconductor.Thesignalsononeinterconnectwillaffectandbeaffectedbythesignalsonanother.Furthermore,athighfrequencies,…信號不再僅僅存在于導(dǎo)體內(nèi)，也在導(dǎo)體外產(chǎn)生磁場。LessonOne

ModernDigitalDesign&Digital

SignalProcessing

TextB

ModernDigitalDesign

NewWordsandExpressionsconductor

n.導(dǎo)線，導(dǎo)體socket

n.插座(承窩,管套)bus

n.母線,總線siliconprocess

硅過程，硅加工transient

n.瞬變現(xiàn)象,瞬態(tài)，暫態(tài)delay

n.延遲glitch

n.(俚)短時脈沖波形干擾,

失靈,小故障transmissionline

傳輸線，波導(dǎo)線LessonOne

ModernDigitalDesign&Digital

SignalProcessing

TextB

ModernDigitalDesign

volume-manufactured

大量制造的motherboard

n.母板high-frequencyeffects

高頻效應(yīng)conductive

a.傳導(dǎo)的(導(dǎo)電的)connector

n.連接物(接線器,插頭)thresholdregion

臨界域parasitic

a.寄生的impedance

n.阻抗distortion

n.失真LessonTwo

EmbeddedSystemsandApplications＊TextA:CharacteristicsofEmbeddedSystems＊TextB:DesignLanguagesforEmbeddedSystemsLessonTwo

EmbeddedSystemsandApplications

TextA

CharacteristicsofEmbeddedSystems

Eventhetoolsweuseformanufacturingaretheresultofembeddedsystems.Itstandstoreasonthattherearecompaniesthatspecializeinthedevelopmentofembeddedsystems,eitherindependently,orintandemwiththemachinerywithwhichthey'retobeused.Moreandmore,engineeringfirmsarecallingonthiskindofexpertisetoUpgradetheirproductsineverywayimaginable.這就很容易理解為什么越來越多的公司致力于嵌入式系統(tǒng)的開發(fā)，他們或獨(dú)立開發(fā)操作系統(tǒng)，或連帶開發(fā)相關(guān)芯片，與此同時，越來越多的工程公司也在不斷研究利用這種技術(shù)，運(yùn)用它從而實(shí)現(xiàn)其產(chǎn)品的全面升級。LessonTwo

EmbeddedSystemsandApplications

TextA

CharacteristicsofEmbeddedSystemsManyotherembeddedsystems,thoughnotsoprice-sensitive,havephysicalconstraintsonformfactororweighttousethesmallestcomponentspossible.Again,thisfavorsperformanceoptimizationatthecostofmaintainability.還有一種可能，即用戶并不在乎嵌入式系統(tǒng)的價格，而對外形尺寸、重量等物理?xiàng)l件有較高的要求，要求使用體積最小的器件，針對尺寸的優(yōu)化過程是以犧牲系統(tǒng)的穩(wěn)定性為代價的。LessonTwo

EmbeddedSystemsandApplications

TextA

CharacteristicsofEmbeddedSystems

Bynature,…Therearegenerallybothhardreal-timeconstraints,whichrequireaneventtobehandledbyafixedtime,andsoftreal-timeconstraints,whichsetlimitsontheaverageeventresponsetime.Real-timeoperatingsystemsusepreemptiveprioritizedschedulingtohelpensurethatreal-timedeadlinesaremet,…嵌入式系統(tǒng)既要受到硬實(shí)時限制，也要受到軟實(shí)時限制，前者要求某個進(jìn)程必須在固定時間內(nèi)完成，后者則確定了平均響應(yīng)時間。LessonTwo

EmbeddedSystemsandApplications

TextA

CharacteristicsofEmbeddedSystemsFurthermore,forseveraltypesofembeddedsystems,itisdifficultorevenimpossibletoupgradefirmware,whichemphasizestheneedto“getitright”inthesystem’sinitialcommercialrelease.另外，有的嵌入式系統(tǒng)固化軟件升級困難，甚至不能實(shí)現(xiàn)升級，這就要求系統(tǒng)在投入市場時必須做到“起步正確”。LessonTwo

EmbeddedSystemsandApplications

TextA

CharacteristicsofEmbeddedSystemsNewWordsandExpressionsembeddedsystems

嵌入式系統(tǒng)micro-controller

n.微控制器real-time

實(shí)時PDA

abbr.PersonalDigitalAssistant

個人數(shù)字助理（即掌上型電腦）monolithic

n.單片電路,單塊集成電路cross-coupling

交叉耦合solarpanels

太陽電池板communicationsprotocols

通信協(xié)議LessonTwo

EmbeddedSystemsandApplications

TextA

CharacteristicsofEmbeddedSystemscompiler

n.編輯者,[計(jì)]編譯器robustnessn.健壯性modularityn.[計(jì)]模塊性executioncontext[計(jì)]執(zhí)行文本FPGAabbr.可編程器件ASICabbr.[電]特定用途集成電路cohesionn.結(jié)合,凝聚,[物理]內(nèi)聚力architecturen.建筑,建筑學(xué)體系機(jī)構(gòu)LessonTwo

EmbeddedSystemsandApplications

TextB

DesignLanguagesforEmbeddedSystemsBecausethetasksmustsolvediverseproblems,alanguagegeneral-purposeenoughtosolvethemallwouldbedifficulttowrite,analyze,andcompile.Instead,avarietyoflanguageshaveevolved,eachbestsuitedtoaparticularProblemdomain.Forexample,alanguageforsignalprocessingisoftenmoreconvenientforaparticularproblemthan,say,assembly,butmightbepoorforcontrol-dominatedbehavior.由于這些任務(wù)需要解決很多問題，若采用通用語言，無論是程序的編寫，還是程序的分析和編譯都會十分困難，因此需要采用多種語言，在解決不同的特定問題時采用不同的語言。信號處理中采用的語言，如匯編語言，比其他語言更適合解決特定問題，但是，它卻不適合于控制領(lǐng)域的應(yīng)用。LessonTwo

EmbeddedSystemsandApplications

TextB

DesignLanguagesforEmbeddedSystems

ACprogramcontainsfunctionsbuiltfromarithmeticexpressionsstructuredwithloopsandconditionalsInstructionsinaCprogramrunsequentially,…

Whencontrolreachesafunctioncallinanexpressioncontrolispassedtothecalledfunction,whichrunsuntilitproducesaresult,andcontrolreturnstocontinueevaluatingtheexpressionthatcalledthefunction.當(dāng)程序計(jì)算包含某個功能函數(shù)的表達(dá)式時，將會調(diào)用這個功能函數(shù)，功能函數(shù)返回運(yùn)行結(jié)果后，程序帶入該結(jié)果，并繼續(xù)計(jì)算表達(dá)式。LessonTwo

EmbeddedSystemsandApplications

TextB

DesignLanguagesforEmbeddedSystems

Dataflowlanguagesdescribesystemsofproceduralprocessesthatrunconcurrentlyandcommunicatethroughqueues.…

Dataflowsemanticsarenaturalforexpressingtheblockdiagramstypicallyusedtodescribesignal-processingalgorithms,andtheirregularitymakesdataflowimplementationsveryefficientbecauseotherwisecostlyrun-timeschedulingdecisionscanbemadeatcompiletimeeveninsystemscontainingmultiplesamplingrates.數(shù)據(jù)流語言適合于表示方塊圖，常用于描述信號處理算法。數(shù)據(jù)流語言能提高數(shù)據(jù)流的運(yùn)行效率，因?yàn)榧词乖诙喾N抽樣速率下，它也能在編譯時完成耗費(fèi)系統(tǒng)資源較多的進(jìn)程，如運(yùn)行模式選擇進(jìn)程。LessonTwo

EmbeddedSystemsandApplications

TextB

DesignLanguagesforEmbeddedSystems

SDLisagraphicalspecificationlanguagedevelopedfordescribingtelecommunicationprotocolsdefinedbytheITU.Asystemconsistsofconcurrently-runningFSMs,eachwithasingleinputqueue,connectedbychannelsthatdefinewhichmessagestheycarry.EachFSMconsumesthemostrecentmessageinitsqueue,reactstoitbychanginginternalstateorsendingmessagestootherFSMs,…SDL是用于描述國際電信聯(lián)盟（ITU）定義的電信協(xié)議的一種圖形說明語言。LessonTwo

EmbeddedSystemsandApplications

TextB

DesignLanguagesforEmbeddedSystemsNewWordsandExpressionsmemorylocations

存儲單元raceconditions

[電]紊亂情況；競態(tài)條件iterator

n.[計(jì)]迭代器，迭代程序verbose

a.詳細(xì)的,冗長的functioncall

函數(shù)引用[調(diào)用]groupobjects

n.[計(jì)](程序)組對象synchronize

v.同步,整步,使…同步化singleprocessor

單一處理機(jī)blockdiagrams

結(jié)構(gòu)圖，方塊圖,簡圖LessonThree

VirtualInstruments＊TextA:AboutVirtualInstrumentation

＊TextB:WhatExactlyIsLabVIEW,andWhatCanItDoForMeLessonThree

VirtualInstruments

TextA

AboutVirtualInstrumentation

Withvirtualinstrumentation,softwarebasedonuserrequirementsdefinesgeneral-purposemeasurementandcontrolhardwarefunctionality.Virtualinstrumentationcombinesmainstreamcommercialtechnologies,suchasthePC,withflexiblesoftwareandawidevarietyofmeasurementandcontrolhardware,soengineersandscientistscancreateuserdefinedsystemsthatmeettheirexactapplicationneeds.(seeFigure1)…虛擬儀器將主流商業(yè)技術(shù)，如PC，與靈活的軟件和多種測量控制硬件相結(jié)合，使得工程師和科學(xué)家得以根據(jù)用戶的需要組成用戶自定義系統(tǒng)。LessonThree

VirtualInstruments

TextA

AboutVirtualInstrumentation

Virtualinstrumentationisnecessarybecauseitdeliversinstrumentationwiththerapidadaptabilityrequiredfortoday’sconcept,product,andprocessdesign,development,anddelivery.Onlywithvirtualinstrumentationcanengineersandscientistscreatetheuserdefinedinstrumentsrequiredtokeepupwiththeworld’sdemands.只有采用虛擬儀器，工程師和科學(xué)家們才能適應(yīng)不斷變化的需求，組成由用戶定義的設(shè)備。句中“Onlywith…”引導(dǎo)了一個倒裝結(jié)構(gòu)。LessonThree

VirtualInstruments

TextA

AboutVirtualInstrumentationHowever,thisincreaseinfunctionalitycomeswithaprice.Upgradedfunctionalityintroducesthepossibilityofunforeseeninteractionorerror.So,justasdevice-levelsoftwarehelpsrapidlydevelopandextendfunctionality,designandtestinstrumentationalsomustadapttoverifytheimprovements.設(shè)備級的軟件能快速開發(fā)、擴(kuò)展系統(tǒng)功能，而設(shè)計(jì)與測試設(shè)備必須為這些功能提供驗(yàn)證工具。LessonThree

VirtualInstruments

TextA

AboutVirtualInstrumentation

Thethird,virtualinstrumentationelement–usingcommercialplatforms,oftenenhancedwithaccuratesynchronization–ensuresthatvirtualinstrumentationtakesadvantageoftheverylatestcomputercapabilitiesanddatatransfertechnologies.Thiselementdeliversvirtualinstrumentationonalong-termtechnologybasethatscaleswiththehighinvestmentsmadeinprocessors,buses,andmore.這個因素使得虛擬儀器成為一種影響處理器、總線等產(chǎn)業(yè)技術(shù)投資力度的長線技術(shù)。LessonThree

VirtualInstruments

TextA

AboutVirtualInstrumentation

Finally,…TheLabVIEWgraphicaldevelopmentenvironmentofferstheperformanceandflexibilityofaprogramminglanguage,aswellashighlevelfunctionalityandconfigurationutilitiesdesignedspecificallyformeasurementandautomationapplications.LabVIEW圖形開發(fā)環(huán)境提供了靈活、有效的編程語言，同時也提供了用于測量和自動化應(yīng)用的高級功能模塊和配置工具程序。LessonThree

VirtualInstruments

TextA

AboutVirtualInstrumentationNewWordsandExpressionsconcurrentoperation并發(fā)操作Moore’slaw摩爾氏定律actuatorn.[電信]激勵器；調(diào)節(jié)器prototypingn.原型；標(biāo)準(zhǔn)vibrationn.振動breadthn.寬度；幅度drag-and-drop拖放LessonThree

VirtualInstruments

TextB

WhatExactlyIsLabVIEW,andWhatCanItDoForMe

You'dprobablyliketoknowwhatexactlyLabVIEWisbeforeyougomuchfurther.Whatcanyoudowithitandwhatcanitdoforyou?

LabVIEW,shortforLaboratoryVirtualInstrumentEngineeringWorkbench,isaprogrammingenvironmentinwhichyoucreateprogramswithgraphics;inthisregarditdiffersfromtraditionalprogramminglanguageslikeC,C++,orJava,inwhichyouprogramwithtext.…實(shí)驗(yàn)室虛擬儀器工程平臺，簡稱“LabVIEW”，提供一種圖形化編程環(huán)境，它與傳統(tǒng)的，用文本編程的編程語言（如C，C++，Java）是不同的。LessonThree

VirtualInstruments

TextB

WhatExactlyIsLabVIEW,andWhatCanItDoForMe

Providingyouwithaverypowerfulgraphicalprogramminglanguage,LabVIEWcanincreaseyourproductivitybyordersofmagnitude.ProgramsthattakeweeksormonthstowriteusingconventionalprogramminglanguagescanbecompletedinhoursusingLabVIEW,becauseitisspecificallydesignedtotakemeasurements,analyzedata,andpresentresultstotheuser.…LabVIEW提供一種強(qiáng)大的圖形化編程語言，可以大大地提高工作效率。LessonThree

VirtualInstruments

TextB

WhatExactlyIsLabVIEW,andWhatCanItDoForMe

TheLabVIEWprogramdevelopmentenvironmentisdifferentfromcommercialCorJavadevelopmentsystemsinoneimportantrespect.…Withthismethod,youcanconcentrateontheflowofdatawithinyourapplication;thesimplersyntaxdoesn'tobscurewhattheprogramisdoing.…出于這種思路，你可以將注意力集中在應(yīng)用的數(shù)據(jù)流上，編程所采用的簡單句法使得程序的功能目的一目了然。LessonThree

VirtualInstruments

TextB

WhatExactlyIsLabVIEW,andWhatCanItDoForMe

LabVIEWusesterminology,icons,andideasfamiliartoscientistsandengineers.…Theprincipleofdataflow,inwhichfunctionsexecuteonlyafterreceivingthenecessarydata,governsexecutioninastraightforwardmanner.YoucanlearnLabVIEWevenifyouhavelittleornoprogrammingexperience,…“數(shù)據(jù)流”原理：只有在獲得必要數(shù)據(jù)后，才運(yùn)行功能模塊，它的控制執(zhí)行方式采用的是直接方式。LessonThree

VirtualInstruments

TextB

WhatExactlyIsLabVIEW,andWhatCanItDoForMeNewWordsandExpressionsMacOS

蘋果機(jī)操作系統(tǒng)Solaris諸如SUN這種大型工作站所用的一種操作系統(tǒng)HP-UX隸屬于Unix的一種操作系統(tǒng)plug-inhardware插入式硬件subroutinen.子程序memoryallocation內(nèi)存配置regressionn.回歸LessonFour

DesignPatterns＊TextA:IntrotoDesignPatterns(1)＊TextB:IntrotoDesignPatterns(2)LessonFour

DesignPatterns

TextA

IntrotoDesignPatterns(1)

Inthischapter,you’lllearnwhy(andhow)youcanexploitthewisdomandlessonslearnedbyotherdevelopers…h(huán)owonepatternworks.Thebestwaytousepatternsistoloadyourbrainwiththemandthenrecognizeplacesinyourdesignsandexistingapplicationswhereyoucanapplythem.Insteadofcodereuse,withpatternsyougetexperiencereuse.使用設(shè)計(jì)模式最好的辦法是將它們裝進(jìn)你的腦袋里，然后在你設(shè)計(jì)的現(xiàn)有程序中找到合適的地方把它們放進(jìn)去。它不是代碼復(fù)用，使用模式是經(jīng)驗(yàn)復(fù)用。LessonFour

DesignPatterns

TextA

IntrotoDesignPatterns(1)

Inthelastyear,thecompanyhasbeenunderincreasingpressurefromcompetitors.Afteraweek-longoff-sitebrainstormingsessionovergolf,thecompanyexecutivesthinkit'stimeforabiginnovation.TheyneedsomethingreallyimpressivetoshowattheupcomingshareholdersmeetinginMauinextweek.

去年，公司的競爭壓力加劇。在為期一周的高爾夫假期兼頭腦風(fēng)暴會議之后，公司主管認(rèn)為該是創(chuàng)新的時候了，他們需要在“下周”毛伊島股東會議上展示一些“真正”讓人印象深刻的東西來振奮人心。LessonFour

DesignPatterns

TextA

IntrotoDesignPatterns(1)

Joerealizedthatinheritanceprobablywasn'ttheanswer,becausehejustgotamemothatsaysthattheexecutivesnowwanttoupdatetheproducteverysixmonths(inwaystheyhaven'tyetdecidedon).Joeknowsthespecwillkeepchangingandhe'llbeforcedtolookatandpossiblyoverridefly()andquack()foreverynewDucksubclassthat'severaddedtotheprogram…forever.

Joe認(rèn)識到繼承可能不是答案，因?yàn)樗麆倓偰玫絹碜灾鞴艿膫渫?，希望以后?個月更新一次產(chǎn)品（至于更新的方法，他們還沒想到）。Joe知道規(guī)格會常常改變，每當(dāng)有新的鴨子子類出現(xiàn)，他就要被迫檢查并可能需要覆蓋fly()和quark()…這簡直是無窮無盡的噩夢。

LessonFour

DesignPatterns

TextA

IntrotoDesignPatterns(1)

AtthispointyoumightbewaitingforaDesignPatterntocomeridinginonawhitehorseandsavetheday.Butwhatfunwouldthatbe?No,we'regoingtofigureoutasolutiontheold-fashionedway—byapplyinggoodOOsoftwaredesignprinciples.

此時，你可能正期盼著設(shè)計(jì)模式能騎著白馬來解救你離開苦難的一天。但是，如果直接告訴你答案，這有什么樂趣？我們會用老方法找出一個解決之道：“采用良好的面向?qū)ο筌浖O(shè)計(jì)原則”。

LessonFour

DesignPatterns

TextA

IntrotoDesignPatterns(1)

Nomatterwhereyouwork,whatyou'rebuilding,orwhatlanguageyouareprogrammingin,what'stheonetrueconstantthatwillbewithyoualways?Nomatterhowwellyoudesignanapplication,overtimeanapplicationmustgrowandchangeoritwilldie.不管你在何處工作，構(gòu)建些什么，用何種編程語言，在軟件開發(fā)上，一直伴隨你的那個不變真理是什么？

不管當(dāng)初軟件設(shè)計(jì)得有多好，一段時間之后，總是需要成長與改變，否則軟件會“死亡”。LessonFour

DesignPatterns

TextA

IntrotoDesignPatterns(1)NewWordsandExpressionsdesignpattern

n.設(shè)計(jì)模式superclass

n.超類；父類inherit

vt.繼承competitorn.競爭者executive

n.

經(jīng)理主管人員innovation

n.改革；創(chuàng)新OO(ObjectOriented)

面向?qū)ο蟮膃ncapsulate

vt.封裝LessonFour

DesignPatterns

TextA

IntrotoDesignPatterns(1)dynamically

adv.動態(tài)地impressive

adj.給人印象深刻的shareholdersmeetingn.股東大會exploit

v.充分利用LessonFour

DesignPatterns

TextB

IntrotoDesignPatterns(2)

Okay,nowthatwe'vedonethedeepdiveontheducksimulatordesign,it'stimetocomebackupforairandtakealookatthebigpicture.好，我們已經(jīng)深入研究了鴨子模擬器的設(shè)計(jì)，該是將頭探出水面，呼吸空氣的時候了?，F(xiàn)在就來看看整體的格局。

LessonFour

DesignPatterns

TextB

IntrotoDesignPatterns(2)

Asyou'veseen,creatingsystemsusingcompositiongivesyoualotmoreflexibility.Notonlydoesitletyouencapsulateafamilyofalgorithmsintotheirownsetofclasses,butitalsoletsyouchangebehavioratruntimeaslongastheobjectyou'recomposingwithimplementsthecorrectbehaviorinterface.如你所見，使用組合建立系統(tǒng)具有很大的彈性，不僅可將算法封裝成類，更可以“在運(yùn)行時動態(tài)地改變行為”，只要組合的行為對象符合正確的接口標(biāo)準(zhǔn)即可。

LessonFour

DesignPatterns

TextB

IntrotoDesignPatterns(2)Thestrategypatterndefinesafamilyofalgorithms,encapsulateseachone,andmakestheminterchangeable.Strategyletsthealgorithmvaryindependentlyfromclientsthatuseit.策略模式定義了一組算法，將每個算法封裝起來，并使其可以互換。策略模式使得算法可以獨(dú)立于使用它們的客戶變化。

LessonFour

DesignPatterns

TextB

IntrotoDesignPatterns(2)

Designpatternsgivesyouasharedvocabularywithotherdevelopers.Onceyou'vegotthevocabularyyoucanmoreeasilycommunicatewithotherdevelopersandinspirethosewhodon'tknowpatternstostartlearningthem.Italsoelevatesyourthinkingaboutarchitecturesbylettingyouthinkatthepatternlevel,notthenittygrittyobjectlevel.設(shè)計(jì)模式讓你和其他開發(fā)人員之間有共享的詞匯，一旦懂得這些詞匯，和其他開發(fā)人員之間溝通就很容易，也會促使那些不懂的程序員想開始學(xué)習(xí)設(shè)計(jì)模式。設(shè)計(jì)模式也可以把你的思考架構(gòu)的層次提高到模式層面，而不是僅反停留在瑣碎的對象上。LessonFour

DesignPatterns

TextB

IntrotoDesignPatterns(2)

Talkingatthepatternlevelallowsyoutostay"inthedesign"longer.Talkingaboutsoftwaresystemsusingpatternsallowsyoutokeepthediscussionatthedesignlevel,withouthavingtodivedowntothenittygrittydetailsofimplementingobjectsandclasses.將說話的方式保持在模式層次，可讓你待在“設(shè)計(jì)圈子”久一點(diǎn)。使用模式談?wù)撥浖到y(tǒng)，可以讓你保持在設(shè)計(jì)層次，不會被壓低到對象與類這種瑣碎的事情上面。想想看，有多少次的設(shè)計(jì)會議中，你們一不小心就進(jìn)入了瑣碎的實(shí)現(xiàn)細(xì)節(jié)的討論上。LessonFour

DesignPatterns

TextB

IntrotoDesignPatterns(2)NewWordsandExpressionscomposition

n.合成overhear