2022年信息科學(xué)與電子工程專業(yè)英語課后翻譯答案

Unit1Exercises(1)TranslatethefollowingsentencesintoChinese.1.2.3.Aswithseriesresonance,thegreatertheresistanceinthecircuitthelowertheQand,accordingly,theflatterandbroadertheresonancecurveofeitherlinecurrentorcircuitimpedance.對于串聯(lián)諧振,電路中電阻愈大Q值就愈低,相應(yīng)地線路電流或電路阻抗諧振曲線也就愈平、愈寬。Awirecarryingacurrentlooksexactlythesameandweighsexactlythesameasitdoeswhenitisnotcarryingacurrent.一根帶電導(dǎo)線其外表與重量都與不帶電導(dǎo)線完全同樣。Clickmouseonthewaveformanddragittochangethepulserepetitionrate,ordirectlyenteranewvalueoftheperiodintheprovideddialoguebox,whilekeepingthepulsewidthunchanged.在波形上點擊鼠標(biāo)并拖動來變化脈沖重復(fù)頻率,或者在提供對話框中直接輸入新周期值,而保持脈沖寬度不變。4.Electronicsisthescienceandthetechnologyofthepassageofchargedparticlesinagas,inavacuum,orinasemiconductor.Pleasenotethatparticlemotionconfinedwithinametalonlyisnotconsideredelectronics.電子學(xué)是一門關(guān)于帶電粒子在氣體、真空或半導(dǎo)體中運動科學(xué)技術(shù)。注意,在本書中粒子運動僅限于金屬狀況不屬于電子學(xué)。5.6.Hardwaretechnologieshaveplayedvitalrolesinourabilitytouseelectronicpropertiestoprocessinformation,butsoftwareanddataprocessingaspectshavenotdevelopedatthesamespeed.硬件技術(shù)在我們使用電子特性來解決信息能力中始終起著重要作用,而軟件及數(shù)字解決方面卻沒能與硬件同步發(fā)展。However,inaproperlydesignedDCamplifiertheeffectoftransistorparametervariation,otherthanIco,maybepracticallyeliminatediftheoperationpointofeachstageisadjustedsothatitremainsinthelinearoperationrangeofthetransistorastemperaturevaries.然而在設(shè)計得當(dāng)直流放大器中,若調(diào)節(jié)每一級工作點使之在溫度變化時保持在晶體管線性區(qū),就能在事實上消除Ico以外晶體管參數(shù)變化所導(dǎo)致影響。Unit2Exercises(1)TranslatethefollowingsentencesintoChinese.1.2.3.Ifanalogsignalsaretobetransmitteddigitally,theyfirsthavetobesampledataspecifiedrateandfurtherconvertedtodiscreteamplitudesamplesbyquantization.如果要以方式傳播模擬信號轉(zhuǎn)換為離散幅度樣本。,一方面必要以一定頻率對信號進行采樣,然后通過量化進一步將它們Linearfiltersamplifyorattenuateselectedspatialfrequencies,canachievesucheffectsassmoothingandsharpening,andusuallyformthebasisofre-samplingandboundarydetectionalgorithms.線性濾波器放大或衰減選取空間頻率,可以實現(xiàn)像平滑和銳化這些效果,普通是重采樣和邊沿檢測算法基本。Stabilityandrepeatabilityarefundamentalattributesofdigitalcircuits,however,andthenecessaryaccuracycanbeobtainedinadigitalversionofthemodulatorbyanappropriatechoiceofwordlengthtorepresentthesignals.但是穩(wěn)定性和可重復(fù)性是數(shù)字電路字長而獲得。Thefirstobservationismadeonthefundamentalrelationshipbetweenthenatureofsystem基本性質(zhì),在數(shù)字式調(diào)制器中必要精度可通過恰本地選取代表信號4.andtheperiodicityofitsfrequencyresponse:acontinuoussystemhasanaperiodicfrequencyresponse,

whileadiscretesystemhasaperiodicfrequencyresponse.從系統(tǒng)性質(zhì)和它頻率響應(yīng)周期性之間基本關(guān)系中一方面可以看到:持續(xù)系統(tǒng)有非周期性頻率響應(yīng),而離散系統(tǒng)有周期性頻率響應(yīng)。5.Themainfunctionofthereceiveristoextracttheinputmessagesignalfromthedegradedversionofthetransmittedsignalcomingfromthechannel.接受器重要功能是從由信道傳播來退化了信號中提取出輸入消息。Unit3Exercises(1)TranslatethefollowingsentencesintoChinese.1.2.Averycommonlyusedmethodofmicrowavemeasurementsisbasedonthestudyofastandingwavepatternformedalongthelinebecauseoftheinterferenceofincidentandreflectedwaves.一種很慣用微波測量辦法是基于對駐波圖型研究,這種駐波是由入射波和反射波之間干涉而沿著傳播線形成。Computationsshowareductionof6dBintheEMfieldintensitywiththedistancedoubled,andanincreaseof3dBintheintensitywiththetransmittedpowerdoubled.Thisresultprovidesverificationtothealgorithmused.計算表白,當(dāng)距離增大一倍時,電磁場強度減小6分貝;而發(fā)射功率增大一倍時,場強則增長3分貝。這一成果驗證了所用算法對的性。3.Liketransferofheatbyconduction,convectionandradiation,microwaveheatingcanbeconsideredasanothermodeofheattransfer,inwhichheatisproduceddirectlyatthelocationofthedielectriclosses.就像通過傳導(dǎo)、對流、輻射來傳遞熱量同樣,微波加熱可以看作熱傳遞另一種方式,即熱量直接產(chǎn)生于發(fā)生介電損耗地方。4.5.Operationoftheradarisbasedonthemeasurementofthetimeittakesforapulsetransmittedfromanantennatogetreflectedbytheobjecttobedetectedandtoreturnattheantennaandthereceiver.雷達工作是基于對天線發(fā)出脈沖被所要探測目的反射,(然后)回到天線和接受機所需時間測量。OthermotivationsforusingCADincircuitdesignincludesthewishtoacquireconfidenceinadesignthatwasaccomplishedbyothermeans,and,notleastinimportance,asenseofcuriosityorperhapsadesiretodiscovertheunexpected.在電路設(shè)計中使用CAD其他動機涉及:想要驗證用設(shè)計出來電路;滿足好奇心或者也許是想發(fā)別辦法現(xiàn)預(yù)想不到現(xiàn)象。后一種動機并非是最不重要。(獲得信心,并非最不重要,意料之外事)6.7.Thespacingbetweentherepeatingamplifiersisafunctionofthecableattenuationandthesystembandwidthsothatthegainprovidedbytheseamplifierscompensatesforthelossintroducedbythecable.中繼放大器之間間距是電纜衰減和系統(tǒng)帶寬函數(shù),以便這些放大器提供增益補償電纜引起損耗。Whenthecut-offfrequencyisnolessthanthemaximalfrequencyoftheoriginalsignal,norisitgreaterthanthedifferencebetweenthesamplingfrequencyandthemaximalfrequency,theoriginalsignalmaybecompletelyrebuilt.當(dāng)截止頻率不不大于原始信號最高頻率,也不不不大于采樣頻率和最高頻率之差,原始信號可以完整地重建。8.WhilethepoliticsofthelastonehundredyearscenteredaroundIndustrialAgetechnology,thepoliticsofthefuturewillbebasedonInformationAgeconcernsorientedtowardsthestorage,protectionandexchangeofinformation.盡管近百年來政治活動是以工業(yè)時代技術(shù)為中心,將來政治活動將基于信息時代事物,面向信息存儲、保護和互換。

Unit4Exercises(1)TranslatethefollowingpassagesintoChinese.1.Communicationmaybebroadlydefinedasthetransferofinformationfromonepointtoanother.Whentheinformationistobeconveyedoveranydistanceacommunicationsystemisusuallyrequired.Withinacommunicationsystemtheinformationtransferisfrequentlyachievedbysuperimposingormodulatingtheinformationontoanelectromagneticwavewhichactsasacarrierfortheinformationsignal.Thismodulatedcarrieristhentransmittedtotherequireddestinationwhereitisreceivedandtheoriginalinformationsignalisobtainedbydemodulation.Sophisticatedtechniqueshavebeendevelopedforthisprocessbyusingelectromagneticcarrierwavesoperatingatradiofrequenciesaswellasmicrowaveandmillimeterwavefrequencies.However,communicationmayalsobeachievedbyusinganelectromagneticcarrierthatisselectedfromtheopticalrangeoffrequencies.通信可以廣義地定義為從一處到另一處信息傳遞。當(dāng)要將信息傳播到任何距離以外時就需要有一種通信系統(tǒng)。在通信系統(tǒng)內(nèi)部,信息傳播經(jīng)常通過將信息疊加或調(diào)制到作為信號載體電磁波上來實現(xiàn)。經(jīng)調(diào)制載波然后被傳送到規(guī)定目地,在那里被接受,原始信號通過解調(diào)被恢復(fù)出來。為了實現(xiàn)這一過程,已經(jīng)運用工作在射頻、微波以及毫米波頻率上電磁載波開發(fā)了復(fù)雜技術(shù)。但是通信也可以用光波頻段上電磁載波來實現(xiàn)。2.Electroniccommunicationsisthetransferandmovementofdatabetweenlocationsthroughtheuseofcomputers.Anelectroniccommunicationsystemincludestheequipmentneededtosupportthemovementofinformation,thecommunicationlinesandmediatocarrytheinformation,thecomputersoftwareandprogramstocontroltheflowofinformation,thepersonneltoplan,implement,andoperatecommunications,andthemanagementofalltheseresources.Electroniccommunicationsestablisheslinksbetweenpeopleaswellascomputers.電子通信就要設(shè)備,承載信息通信對所有這些資源管理。電子通信建立起人和人、計算機和計算機之間聯(lián)系。是通過使用計算機在不同地點之間傳播數(shù)據(jù)。一種電子通信系統(tǒng)涉及:支持信息流動所需線路和媒介,控制信息流計算機軟件和程序,籌、劃實行、操作通信系統(tǒng)人員,以及3.Firstgenerationcommunicationssystemscanbecharacterizedbytheuseofanalogtransmissiontechniques,andtheuseofsimplemultiplexaccesstechniquessuchasfrequencydivisionmultipleaccess(FDMA).Theysufferedfromalowusercapacity,andsecurityproblemsduetothesimpleradiointerfaceused.Secondgenerationsystemswereintroducedintheearly1990’s,andallusedigitaltechnology.Thisprovidedanincreaseintheusercapacityofaroundthreetimes,achievedbycompressingthevoicewaveformsbeforetransmission.Thirdgenerationsystemsareanextensiononthecomplexityofsecond-generationsystemsandaretobeintroducedaftertheyear.Thesystemcapacitywillbeincreasedtoovertentimesoriginalfirstgenerationsystems,achievedbyusingcomplexmultiplexaccesstechniquessuchascodedivisionmultiplexaccess(CDMA),oranextensionofTDMA,andbyimprovingflexibilityofservicesavailable.第一代通信系統(tǒng)以模擬傳播技術(shù)和簡樸復(fù)用技術(shù)如頻分復(fù)用為特性。這使用簡樸無線電接口而存在安全問題。第二代通信系統(tǒng)于20世紀(jì)90年代初開始引入,所有前將話音波形壓縮使得顧客容量提高了三倍。第三代通信系統(tǒng)是對第二代系統(tǒng)在復(fù)雜性方面擴展,預(yù)測于后來啟用。通過雜復(fù)用技術(shù)如CDMA或TDMA擴展,并提高服務(wù)靈活性些系統(tǒng)顧客容量低,并且由于使用數(shù)字技術(shù)。通過在傳播使用復(fù)使得系統(tǒng)容量比本來第一代系統(tǒng)提高10倍。4.Foreachcombinationofcommunication(modulation/detection)type,channelfadingmodel,anddiversitytype,theaveragebiterrorrate(BER)and/orsymbolerrorrate(SER)ofthesystemisobtainedandrepresentedbyanexpressioninaformthatcanreadilybeevaluated.Allcasesconsidered

correspondtorealpracticalchannels,andinmanyinstancestheBERandSERexpressionsobtainedcanbeevaluatednumericallyonahand-heldcalculator.對于通信(調(diào)制/檢測)類型、信道衰落模型、分集類型每一種組合,得到系統(tǒng)平均誤碼率(BER)和符號錯誤率(SER),并以容易求值形式表達。所有考慮相應(yīng)于實際信道狀況,以及許多狀況下得到BER和SER表達式均可用手持計算器來計算。5.Modulationisthesystematicvariationofsomeattributeofacarrierwaveformsuchastheamplitude,phase,orfrequencyinaccordancewithafunctionofthemessagesignal.Itisusedincommunicationsystemsformatchingsignalcharacteristicstochannelcharacteristics,forreducingnoiseandinterference,forsimultaneouslytransmittingseveralsignalsoverasinglechannel,andforovercomingsomeequipmentlimitations.Aconsiderableportionofthisbookisdevotedtothestudyofhowmodulationschemesaredeignedtoachievetheabovetasks.Thesuccessofacommunicationsystemdependstoalargeextentonthemodulation.調(diào)制是載波波形某些屬性,例如幅度、相位和頻率,依照消息信號函數(shù)有規(guī)則變化。它用于通信系統(tǒng)以道上同步傳播各種信號,并克服某些設(shè)備限制。本使信號特性匹配信道特性,減少噪聲和干擾,在單個信書相稱大某些內(nèi)容是研究如何設(shè)計調(diào)制方案以實現(xiàn)上述任務(wù)。一種通信系統(tǒng)成功很大限度上依賴于調(diào)制。Unit5Exercises(1)TranslatethefollowingpassageintoChinese.OFDMconsistsofalargenumberofsubcarriersequallyspacedinafrequencyband,eachmaybedigitallymodulatedbyasameschemesuchasPSK,QAM,etc.,orbydifferentschemes.Aseriallytransmittedsequenceisdividedintoanumberofsections,eachhavingNsymbols,andtheNsymbolsineachsectionareusedtomodulateNcarriersforsimultaneoustransmission.ThereforeOFDMisessentiallyaparallelmodulationsystem.Whenthenumberofsubcarriersissufficientlylarge,thesystemcanresistmultipathinterference.Thisisbecausethat,inthetimedomain,asymboldurationlongerthanthemultipathdelaycanbechosen,whileinthefrequencydomain,eachsymbolonlyoccupiesasmallportionofthechannel’sfrequencyband.Thus,theeffectofmultipathfadingspreadsovermanysymbols,resultinginslightdistortiontomanysymbolsratherthancompletedestroyofafewsymbols.Inthisway,correctdemodulationisnotaffectedsothatthesignalcanbeaccuratelyrecoveredatthereceiver.InanOFDMsystem,theprincipleofchoosingthesubcarrierintervalistomakethesubcarriersmutuallyorthogonalwithintheentiresymbolperiod.Thus,evenifspectraloverlapexistsbetweenthesubcarriers,thesymbolscanstillberecoveredwithoutloss.Inordertorealizemaximumspectralefficiency,theintervalbetweensubcarriersisusuallychosentoequalthereciprocalofthesymboldurationT.Thereforethesubcarrierfrequenciesinthebasebandarefn=n/T,(n=0,1,...,N1).Denotingthen-thmodulatingsymbolasX(n),theOFDMwaveformwithinasymboldurationcanbeexpressedas:nTN1x(t)X(n)exp2jt,0tT(1)(2)n0Samplingthiswaveformatt=T/NyieldsN1Xn()exp2kTjnk,k1,2,,N1NN1x(k)Xn()exp2jNn0n0Itisobservedfromtheaboveexpressionthatx(k)andX(n)formadiscreteFouriertransformpair,thereforethebasebandOFDMwaveformcanbegeneratedfromthediscreteFouriertransformofNmodulatingsymbols.WhenN=2mwheremisaninteger,thefastalgorithmofIDFTiseasytoimplement.OFDM由大量在頻率上等間隔子載波構(gòu)成。每個子載波可用同樣方案,如PSK,QAM等,或者用不同方案數(shù)字調(diào)制。將串行傳播符號序列提成許多段,每一段有N個符號,每段N個符號被用來分別調(diào)制N個載波同步發(fā)送。因而,OFDM本質(zhì)上是一種并行調(diào)制系統(tǒng),當(dāng)載波數(shù)足夠大時,這種系統(tǒng)具備抗多徑干擾能力。這是由于在時域上符號周期能選獲得比多徑延遲時間長,而在頻域上每個符號只占整個信道帶寬一小某些,因而多徑衰落影響被分散到許多符號上,其成果是許多符號都發(fā)生輕度畸變,而不是使某些符號被完全破壞。這樣,不影響對的解調(diào),信號能在接受器中精確地恢復(fù)。在OFDM系統(tǒng)中,選取子載波間隔原則,這樣。雖然在子載波間存在頻譜某些重疊,符號仍能無損失地恢復(fù)。為了實現(xiàn)最大頻譜效符號周期倒數(shù)。因而基帶子載波頻率為fn=n/T,(n=0,1,...,N1),第n個調(diào)制符號記為周期內(nèi)OFDM波形可表達是使子載波在整個符號周期內(nèi)互相正交率,子載波之間間隔普通選用為X(n),在一種符號:nN1x(t)X(n)expj2t,0tT(1)Tn0在t=T/N時刻采樣這個波形得到:N1kTnk,k1,2,,N1X(n)expj2NNN1x(k)X(n)expj2(2)n0n0從上面表達中可以看到,x(k)和X(n)構(gòu)成了一對離散傅里葉變換,因而基帶OFDM波形可依照N個調(diào)制符號離散傅里葉。變換來生成。當(dāng)N=2m,其中m為整數(shù),IDFT迅速算法很容易實現(xiàn)Unit6Exercises(1)TranslatethefollowingsentencesintoChinese.1.2.3.Communicationisthetransmissionofinformationfromonepointtoanother.Thistransmissionrequirestheabilitytovarysignalswithtimeinamannerwhichisunpredictabletothereceiver.通信就是信息從一點傳送到另一點。這種傳送規(guī)定信號隨時間發(fā)生變化不能在接受端預(yù)測。Itistrueofanycommunicationsystemthattheshapeandamplitudeofthetransmittedsignalwillbecontinuouslydegradedbytheintroductionofnoise,andtheattenuationalongthetransmissionpath.傳播信號會不斷地被噪聲引入和線路上衰減所損傷,對任何通信系統(tǒng)都是如此。Sincetheverybeginning,communicationssystemshaveconsistedofthreemajorparts,namely,theequipment,themedium,andtheprotocol.Itisstillthecasetoday.However,thecloselinkoftelecommunicationswiththecomputertechnologyhasbroughtabouttremendouschangesincommunications,fromtheconcepts,tothecontentsandthemethods.4.5.從一開始通信系統(tǒng)就由設(shè)備、媒介和合同三個要素構(gòu)成。至今依然如此。然算機技術(shù)緊密聯(lián)系使得通信從概念到內(nèi)容和手段都發(fā)生了重大變化。Theavailabilityofsuchalargecollectionofsystemperformancecurvesinasinglecompilationallowstheresearcherorsystemdesignertoperformtrade-offstudiesamongthevariouscommunicationtype/fadingchannel/diversitycombinationssoastodeterminetheoptimumchoiceinthefaceofhisorheravailableconstraints.在一本書中提供如此大量系統(tǒng)性能曲線,使研究者或系統(tǒng)設(shè)計者能在各種通信類型、衰落信道、分集佳選。取組合之間進行比較研究,從而在她或她所面臨限制之下做出最6.Thechannelprovidestheelectricalconnectionbetweentheinformationsourceandtheuser.Thechannelcanhavemanydifferentformssuchasamicrowaveradiolinkoverfreespace,apairofwires,oranopticalfiber.信道提供信息源和顧客之間電路聯(lián)接。信道可以有許多不同形式,例如自由空間里微波聯(lián)接,一對電線,或者一根光纖。7.Thedegradationofthetransmittedsignalisaresultofsignaldistortionduetoimperfectresponseofthechannelandduetoundesirableelectricalsignals(noise)andinterference.Noiseandsignaldistortionaretwobasicproblemsofelectricalcommunication.傳播信號退化是信號失真成果,而這種失真又是由信道非抱負(fù)響應(yīng)及不想要電信號(噪聲)和干擾引起。噪聲和信號畸變是電子通信兩個基本問題。Unit8Exercises(1)TranslatethefollowingsentencesintoChinese.1.Earlyinthetwentiethcentury,itwasfoundthatlightcouldcauseatomstoemitelectronsandthat,whenlightreleasedanelectronfromanatom,theenergypossessedbytheelectronverygreatlyexceededthatwhichtheatomcould,accordingtotheelectromagneticwavetheory,havereceived.在二十世紀(jì)初期,人們發(fā)現(xiàn)光可以使原子放出電子,并且當(dāng)光從原子中釋放一種電子時,電子所包括能量大大超過由電磁波理論得到原子所接受能量。2.3.Pulsebroadeningdeterminestheminimumseparationbetweenadjacentpulses,whichinturndeterminesthemaximuminformation-carryingcapacityoftheopticalfiber.脈沖展寬決定了相鄰脈沖之間最小間隔,這一間隔進而又決定了光纖最大信息量容。Ifoneweretotransmitsuchinformationwithoutimpressingitonanopticalcarrierbutinsteadonaradiofrequency(RF)carrierabithigherthanthemaximumrate,thetransmissionwavelengthoftheRFcarrierwouldbecentimetersorlarger.如果傳播這樣信息不是將它加載到光纖上,而是加載在略高于最大速率射頻載波上,則此射頻載波就會是厘米波或是波長更長某些波。4.5.6.Thesmallnessoftheopticalwavelength,therefore,allowsfortheminiaturizationoftransmitandreceivemodules,whichshouldallowconsiderablereductioninsize,weight,andcostofopticalcommunicationsystemswithrespecttomicrowave/radiowavecounterparts.光波波長之小使發(fā)射和接受模塊得以小型化,這就使光通信系統(tǒng)尺寸、重量以至價格與相應(yīng)微波、無線電波通信系統(tǒng)相比都大為減少。Althoughalltheadvantagesofcoherentopticalcommunicationsystemshaveyettobebroughttofruition,anotherpropertyofopticalradiationhasmadetoday’sopticalcommunicationsystemsnotdesirableforapplications.雖然相干光通信系統(tǒng)所有長處尚有待于貫徹在詳細(xì)成果中,光輻射另一性質(zhì)卻使當(dāng)前光通信系統(tǒng)不利于應(yīng)用。Whencoupledwithlight’sshortwavelengthwhichallowsforminiaturesourcesanddetectorsandmicron-sizedwaveguides,directdetectionschemeshaveallowedforsmall,lightweight,highbandwidthsystemswhicharecompetitiveinmanyareas,mostnotablytothepresenttelecommunicationstransmission,althoughamyriadofotherapplicationsarecontinuallyopeningup.光波長很小,可以使用小型光源和檢測器以及微米級波導(dǎo),于是用直接檢測方案可實當(dāng)前許多領(lǐng)域具備競爭力小巧寬帶系統(tǒng),這些領(lǐng)域中特別引人注目是當(dāng)前電信傳播中應(yīng)用,盡管無數(shù)其她應(yīng)用也在不斷涌現(xiàn)出來。7.Asmentionedpreviously,theseapplicationshavetendedtoopenupmoreslowlythanoriginallypredicted,ascostwasreallynotmuchofaconsiderationintelecommunications,whereequipmentcostsareswampedbyotherconsiderations.如前所述,(線路)成本并非電信系統(tǒng)中真正重要考慮因素,通信設(shè)備成本重要受到其她因素制約,因而這些應(yīng)用比預(yù)料浮現(xiàn)得慢。

8.Aswavelengthsdecreasetoapproachthesizeofcircuitcomponents,circuitelementsarenolongerlumpedassuch,andleadscanactasreflectivecomponentsand/orantennasandlumpedelementsaselectromagneticresonators.隨著波長減小到接近于電路元件尺寸,電路單元就不再是集總,導(dǎo)線可起到反射元件以及(或)天線作用,集總單元則成為電磁諧振器。Unit11Exercises1.Inatelevisionscanninggeneratorusingapairoffree-runningrelaxationoscillators,free-runningfrequenciesoftheoscillatorsaresetslightlybelowthehorizontalandverticalpulserates,andthestrippedpulsesareusedtotriggertheoscillatorsprematurelyandthustosynchronizethemtothelineandhalf-framerates.在采用一對自由張弛振蕩器電視掃描發(fā)生器中,振蕩器自由頻率被設(shè)立得略低于水平和垂直(掃描)頻率,分離出來脈沖被用來提前觸發(fā)振蕩器從而使它們與行頻和半幀頻(場頻)同步。Unit12Exercises1.2.Referringtothefigure,weseethatsignalprocessingtechniquesareneededforpreprocessing,patternrecognitiontechniquesareneededforsegmentation,featureextraction,andclassification,andartificialintelligencetechniquesareneededforstructureanalysis,knowledge-acquisitionandrepresentation(worldmodel),andcontrolstructure(interactionamongtheblocks).參照圖,我們看到信號解決技術(shù)是預(yù)解決所需要,模式辨認(rèn)技術(shù)是分割、特性提取以及分類所需要,而人工智能技術(shù)則是構(gòu)造分析、知識獲取及表達(世界模型)以及控制構(gòu)造(塊間交互)所需要。Thepictureelementsacrossalineareconvertedtothevideosignalandlow-passfilteredwithanelectricalfilter.Thissmoothingremovesthediscretestructureinthehorizontaldimension.沿著一條直線圖像像素被轉(zhuǎn)換成視頻信號,然后由一種電子濾波器進行低通濾波。這一平滑解決可消除水平方向離散構(gòu)造。Unit13Exercises(1)TranslatethefollowingsentencesintoChinese.1.2.Theprecedingchaptershavedescribedhowtheautomaticcomputerperforms,buthavenotdescribedhowtheautomaticcomputercanbeputtousetododatahandlingworktoserveanorganization,norwhysuchworkisdoneinthewaythatitis.前面章節(jié)講述了自動計算機是如何工作,但沒有講述自動計算機如何能用于數(shù)據(jù)解決工作以服務(wù)于一種機構(gòu),也沒有講述這種工作為什么用這種辦法實現(xiàn)。Whilethesubjectofcodingoftencarrieswithitanairofsecrecy,amoreimportantmotiveinmanycodingsystemsistheimprovedefficiencyinconveyinginformation.如果說編碼這一主題常帶有一種秘密色彩,那么許多編碼系統(tǒng)一種更重要目則是為了提高信息傳遞效率。Unit14Exercises(1)TranslatethefollowingsentencesintoChinese.1.Theimportanceofearlybraindevelopmentinsettingthefoundationsforlanguageisapparentinbabiesyoungerthan6months.大腦初期發(fā)展對于奠定語言基本重要性在半年如下嬰兒中是顯而易見。Unit15Exercises(1)TranslatethefollowingpassageintoChinese.Becausedigitalimageprocessingdoesencompasssuchawidevarietyoftechniquesandmathematicaltools,eachapplicationinvolvesasequenceofprocessingsteps.Thesestepsaremodulesthatcanbe

arrangedinanenormousnumberofdifferentsequences,andeachmodulegenerallyadmitsthespecificationofparametervaluesthatfurtherexpandtherangeofpossiblemanipulationschemestoachievethedesiredresults.Themajoradvantagesofdigitalimagesascomparedwithanalog(i.e.film)imagesarethequalityofthedataandtheaccessibilityofthatdatatocomputermanipulation.Thequalityadvantageisreallyanaggregateoftwoadvantages:Dynamicrange:upto128ormoregraylevelscanbepresentondigitalimageswhereasonly1530discernibleonfilmproducts.Reproducibility:acopyofacopyofacopyofadigitalimagecontainsexactlythesamedataastheoriginal,whereasaforth-generationphotographicproductissubstantiallydegradedincomparisonwiththeoriginal.Althoughtheseareadvantages,thecompellingadvantagefortheapplicationscommunityderivesfromtheaccessibilityofthedatatocomputermanipulation.Togenerateageneral-purposefilmproductisessentiallytochooseacompromiseamongcompetingrequirementsfromagronomists,hydrologists,foresters,geologists,urbanplanners,andotherusergroups;itisnotoptimizedforanyone.Digitalimageslendthemselvestocustomtailoringbytheuserforhisorherapplicationinawaythatfilmproductscannot.數(shù)字圖像解決涉及了各種各樣技術(shù)和數(shù)學(xué)工具,每一項應(yīng)用都涉及到一系列解決環(huán)節(jié)。這些環(huán)節(jié)是以大量不同順序排列各種模塊,每一模塊普通容許某些參數(shù)值技術(shù)指標(biāo),從而進一步擴大了為獲得預(yù)期成果而也許采用解決方案選取范疇。與模擬圖像(即膠片)相比,數(shù)字圖像重要長處在于數(shù)據(jù)質(zhì)量和數(shù)據(jù)可供計算機進行解決這兩方面。質(zhì)量方面優(yōu)越性事實上是如下兩種優(yōu)越性綜合:動態(tài)范疇:數(shù)字圖像可體現(xiàn)128級或更多灰度,而膠片產(chǎn)品只能辨別15至30級;重現(xiàn)性:一幅數(shù)字圖像多次復(fù)制后仍與原件包括完全相似信息,而一幅第四代照片與原件相比卻大大地退化(損傷)了。Unit16Exercises(1)TranslatethefollowingsentencesintoChinese.1.2.Inrecentyears,therehasbeenatremendousincreaseintheuseofdigitalcomputersandspecial-purposedigitalcircuitryforperformingvariedsignalprocessingfunctionsthatwereoriginallyachievedwithanalogequipment.近年來為實現(xiàn)各種信號解決功能,數(shù)字計算機和專用數(shù)字電路使用有了巨大增長,這些解決功能原先都是用模擬設(shè)備實現(xiàn)。Inthebeginning,computerswereusedtoprocessonlynumericalinformation,butmajorityofourinformationisnon-numericalinnatureandverylittleisknownaboutitsdescriptionandprocessing.一開始計算機只是被用來解決數(shù)值信息,而我們大多數(shù)信息都是非數(shù)值性質(zhì),并且人們對這些信息描述和解決所知甚少。Unit17Exercises(1)TranslatethefollowingpassagesintoChinese.1.Forthefirsttimeeverthelandscapeischanging,ashighvolumepersonalcomputermultimediaapplicationsproliferate.Firstaffectedweremonitors,whichforsometimehaveofferedhigher-than-broadcastspeedandresolution.Onecanexpectcamerastofollow,withhigh-speed,high-resolutiondevicesdrivenbyconsumerdigitalstillcameratechnologyandlower-resolution,ultralowcostunitsdrivenbyentertainment,internetconferencing,andperceptualuserinterfaceapplications.隨著大量個人計算機多媒體應(yīng)用急劇增是顯示屏,相稱長時間以來它已經(jīng)可以提供比廣播級更高辨別率和速度。人們可期待照相機/攝像機也隨之跟上,涉及由民數(shù)字照相機所推動高速度、高辨別率器件,娛樂業(yè)、互聯(lián)網(wǎng)遠(yuǎn)程會議和顧客視覺界面應(yīng)用所推動低辨別率和極低價格設(shè)備IfyoualreadyhavethefastestCPUinaparticularfamilyandstillwantmoreperformance,長,狀況初次發(fā)生了變化。最早受到影響用。2.

thenitmaybemorecost-effectivetoaddsystemRAMorcacheRAMthantoputinaprocessorfromadifferentfamily.Addingsystemmemorycanbringsignificantperformanceincreasesatarelativelylowcost,assumingyouconfigurethememorycorrectly.InadditiontoaddedcacheandsystemRAM,afasterandlargerharddrivecansaveyoutimewhenrunningapplicationsdependentonheavydriveaccessanddatathroughput.Addingagraphicsacceleratorcardcanhelp,too,especiallyifyouarelookingforawaytostayawakewhileyoursystemredrawsimages.如果你已有了某一系列中最快CPU而還想要更多性能插入一枚另一系列解決器更合算。特別是如果你是一名Windows顧客系統(tǒng)內(nèi)存可以較低代價帶來可觀性能提高。除了增長高速緩存或系統(tǒng)RAM,一種更快和更大硬盤可在,如果你使用Windows,并且發(fā)現(xiàn)你在尋找某種途徑使你在系統(tǒng)重顯圖象時能保持“蘇醒”,則特別是如,那么增長系統(tǒng)RAM或高速緩存RAM也許比,假設(shè)你對的地配備內(nèi)存,則增長運營依賴于大量讀寫硬盤和有大量數(shù)據(jù)吞吐時節(jié)約你時間。增長一種圖形加速器也是有益此。3.Inuniversityenvironments,MATLABhasbecomethestandardinstructionaltoolforintroductorycoursesinappliedlinearalgebra,aswellasadvancedcoursesinotherareas.Inindustrialsettings,MATLABisusedforresearchandtosolvepracticalengineeringandmathematicalproblems.Typicalusesincludegeneralpurposenumericalcomputation,algorithmprototyping,andspecialpurposeproblemsolvingwithmatrixformulationsthatariseindisciplinessuchasautomaticcontroltheory,statistics,anddigitalsignalprocessing(time-seriesanalysis).在大學(xué)環(huán)境里,它已界,MATLAB被用于研究和解決實際工程和數(shù)矩陣公式專門問題解決,這些問題是在自動控制理論、記錄、數(shù)字信號解決科中提出來。成為應(yīng)用線性代數(shù)導(dǎo)論以及其她領(lǐng)域中許多高檔課程原則教學(xué)工具。在工業(yè)學(xué)問題。典型應(yīng)用涉及通用數(shù)值計算、算法原型測試以(時間序列分析)等學(xué)及使用4.Multimediaisagenerictermfor“multimediacomputing”or“interactivemultimedia”.Thecomputerandsoftwareareusedtocontrolandnavigatethroughthecommunicationslinks,notonlyoneatthetime,butseveralsimultaneously.Computersystemshavebeenmostdevelopedinusingvisionandhearingtointerfacebetweenthedigitalandanalogueworlds,e.g.,stillandmovingimages,textandgraphicsusethevisualsenses,andaudiouseshearing.Multimediaisdefinedasvisual,audioandtextualinformationwhichcanbepresented,separatelyorsimultaneously,toconveyandpresentinformationinteractivelytousers.Itistechnicallyeasytodigitizetheanalogueformsofthesecommonmediaandhandledbycomputersnowwidelyavailableandinexpensivetobeaccessibletomostusers.多媒體是表達“多媒體計算”或條通信鏈接同步進行瀏覽。在運用視覺和聽覺在數(shù)到極大發(fā)展,例如對靜止和活動圖像、文本和圖形使用視覺,對音頻使用聽覺。多別或同步呈現(xiàn)視頻、音頻、文本信息,用以交互式地將信息傳遞和展示給顧客。普通媒體模擬形式用計算機實現(xiàn)數(shù)字化并加以解決,計算機當(dāng)前已十分普遍,其價格便宜,大多數(shù)顧客都能使用。Theessentialcapabilityofanymultimediacomputersystemistheabilitytoconvertthe“交互式多媒體”普通術(shù)語。計算機和軟件被用于控制并通過不止一字和模擬世界之間進行交互方面,計算機系統(tǒng)已媒體被定義為可以得分技術(shù)上很容易將這些5.analoguesignaltoadigitalformatandtocompressthisinformationusingstandardalgorithms.ThepoweroftheCPUwilldeterminewhetherthisprocesscanbecarriedoutinreal-timeorwhetherithastobedoneoff-line.OriginallythispoweronlyexistedinUNIXsystems,butmorerecentlyithasbecomeavailableinPCsandMacintosh.Thecompressionprocessisnecessaryotherwisethequantityofdatatobestoredandtransmittedwouldbeexcessive.MostPCshaveuntilrecentlydependeduponhardwareencoding/decodingsystems,butthespeedofcurrentprocessorsissuchthatsoftwarecompressionsystemshavebeendeveloped.Theadvantageofthesoftwaresystemsisthatthecompatibilityandinteroperabilityissuescanbehandledmoreeasily,andthecostoftheequipmentisnotraisedbytheneedtopurchaseexpensive

hardwaredevices.任何多媒體計算機基本功能是將模擬信號轉(zhuǎn)換成數(shù)字格式,并用原則算法將此信息壓縮能力。CPU解決能力將決定與否能實時完畢此過程還是必要離線執(zhí)行。原先只有UNIX系統(tǒng)才有這種實時能力,但近年來PC和Macintosh也能勝任(有這種能力)了。壓縮是必要,否則要存儲和傳送數(shù)據(jù)量太大。直到不久前大多數(shù)PC還依賴硬件編解碼系統(tǒng),而當(dāng)前解決器速度已使軟件編解碼系統(tǒng)開發(fā)成為也許。軟件系統(tǒng)長處在于可更以便地解決兼容性和協(xié)同工作問題,并且不會因購買昂貴硬件而提高設(shè)備成本。Unit19Exercises(1)Translatethefollowing