求职简历飞行学院论文翻译格式模板.docx
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求职简历飞行学院论文翻译格式模板.docx
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求职简历飞行学院论文翻译格式模板
学号
2009030350
滨州学院论文翻译
英文题目
Vehicleemissionscontrol
中文题目
机动车排放控制
(系)院
飞行学院
专业
交通运输
班级
2009级2班
学生姓名
王根
指导教师
王海燕袁伟
职称
副教授助教
2011
年
6
月
5
日
Vehicleemissionscontrol(Section)
Vehicleemissionscontrolisthestudyandpracticeofreducingthemotorvehicleemissions--emissionsproducedbymotorvehicles,especiallyinternalcombustionengines.
Emissionsofmanyairpollutantshavebeenshowntohavevarietyofnegativeeffectsonpublichealthandthenaturalenvironment.Emissionsthatareprincipalpollutantsofconcerninclude:
Hydrocarbons-Aclassofburnedorpartiallyburnedfuel,hydrocarbonsaretoxinsandareamajorcontributortosmog,whichcanbeamajorprobleminurbanareas.Prolongedexposuretohydrocarbonscontributestoasthma,liverdisease,andcancer.Regulationsgoverninghydrocarbonsvaryaccordingtotypeofengineandjurisdiction;insomecases,"non-methanehydrocarbons"areregulated,whileinothercases,"totalhydrocarbons"areregulated.Technologyforoneapplication(tomeetanon-methanehydrocarbonstandard)maynotbesuitableforuseinanapplicationthathastomeetatotalhydrocarbonstandard.Methaneisnottoxic,butismoredifficulttobreakdowninacatalyticconverter,soineffecta"non-methanehydrocarbon"standardcanbeconsideredtobelooser.Sincemethaneisagreenhousegas,interestisrisinginhowtoeliminateemissionsofit.
Carbonmonoxide(CO)-Aproductofincompletecombustion,carbonmonoxidereducestheblood'sabilitytocarryoxygen;overexposure(carbonmonoxidepoisoning)maybefatal.
1.History
throughoutthe1950sand1960s,variousfederal,stateandlocalgovernmentsintheUnitedStatesconductedstudiesintothenumeroussourcesofairpollution.Thesestudiesultimatelyattributedasignificantportionofairpollutiontotheautomobile,andconcludedairpollutionisnotboundedbylocalpoliticalboundaries.Atthattime,suchminimalemissioncontrolregulationsasexistedintheU.S.werepromulgatedatthemunicipalor,occasionally,thestatelevel.Theineffectivelocalregulationsweregraduallysupplantedbymorecomprehensivestateandfederalregulations.By1967theStateofCaliforniacreatedtheCaliforniaAirResourcesBoard,andin1970,thefederalUnitedStatesEnvironmentalProtectionAgencywasestablished.Bothagencies,aswellasotherstateagencies,nowcreateandenforceemissionregulationsforautomobilesintheUnitedStates.SimilaragenciesandregulationswerecontemporaneouslydevelopedandimplementedinWesternEurope,Australia,andJapan.
ThefirsteffortatcontrollingpollutionfromautomobileswasthePCV(positivecrankcaseventilation)system.Thisdrawscrankcasefumesheavyinunburnedhydrocarbons—aprecursortophotochemicalsmog— intotheengine'sintaketractsotheyareburnedratherthanreleasedunburnedfromthecrankcaseintotheatmosphere.Positivecrankcaseventilationwasfirstinstalledonawidespreadbasisbylawonallnew1961-modelcarsfirstsoldinCalifornia.Thefollowingyear,NewYorkrequiredit.By1964,mostnewcarssoldintheU.S.weresoequipped,andPCVquicklybecamestandardequipmentonallvehiclesworldwide.
Thefirstlegislatedexhaust(tailpipe)emissionstandardswerepromulgatedbytheStateofCaliforniafor1966modelyearforcarssoldinthatstate,followedbytheUnitedStatesasawholeinmodelyear1968.Thestandardswereprogressivelytightenedyearbyyear,asmandatedbytheEPA.
Bythe1974modelyear,theemissionstandardshadtightenedsuchthatthede-tuningtechniquesusedtomeetthemwereseriouslyreducingengineefficiencyandthusincreasingfuelusage.Thenewemissionstandardsfor1975modelyear,aswellastheincreaseinfuelusage,forcedtheinventionofthecatalyticconverterforafter-treatmentoftheexhaustgas.Thiswasnotpossiblewithexistingleadedgasoline,becausetheleadresiduecontaminatedtheplatinumcatalyst.In1972,GeneralMotorsproposedtotheAmericanPetroleumInstitutetheeliminationofleadedfuelsfor1975andlatermodelyearcars.Theproductionanddistributionofunleadedfuelwasamajorchallenge,butitwascompletedsuccessfullyintimeforthe1975modelyearcars.Allmoderncarsarenowequippedwithcatalyticconvertersandunleadedfuelcannowbefoundalmosteverywhere.
Regulatoryagencies
Theagencieschargedwithregulatingexhaustemissionsvaryfromjurisdictiontojurisdiction,eveninthesamecountry.Forexample,intheUnitedStates,overallresponsibilitybelongstotheEPA,butduetospecialrequirementsoftheStateofCalifornia,emissionsinCaliforniaareregulatedbytheAirResourcesBoard.InTexas,theTexasRailroadCommissionisresponsibleforregulatingemissionsfromLPG-fueledrichburnengines(butnotgasoline-fueledrichburnengines).
Ultimately,theEuropeanUnionhascontroloverregulationofemissionsinEUmemberstates;however,manymemberstateshavetheirowngovernmentbodiestoenforceandimplementtheseregulationsintheirrespectivecountries.Inshort,theEUformsthepolicy(bysettinglimitssuchastheEuropeanemissionstandard)andthememberstatesdecidehowtobestimplementitintheirowncountry.
IntheUnitedKingdom,mattersconcerningenvironmentalpolicyarewhatisknownas"devolvedpowers"whichmeans,eachoftheconstituentcountriesdealswithitseparatelythroughtheirowngovernmentbodiessetuptodealwithenvironmentalissuesintheirrespectivecountry:
However,manyUK-widepoliciesarehandledbytheDepartmentoftheEnvironmentFoodandRuralAffairs(DEFRA)andtheyarestillsubjecttoEUregulations.
2.Emissionscontrol
Engineefficiencyhasbeensteadilyimprovedwithimprovedenginedesign,morepreciseignitiontimingandelectronicignition,moreprecisefuelmetering,andcomputerisedenginemanagement.
Advancesinengineandvehicletechnologycontinuallyreducethetoxicityofexhaustleavingtheengine,butthesealonehavegenerallybeenprovedinsufficienttomeetemissionsgoals.Therefore,technologiestodetoxifytheexhaustareanessentialpartofemissionscontrol.
(1)Airinjection
Oneofthefirst-developedexhaustemissioncontrolsystemsissecondaryairinjection.Originally,thissystemwasusedtoinjectairintotheengine'sexhaustportstoprovideoxygensounburnedandpartially-burnedhydrocarbonsintheexhaustwouldfinishburning.Airinjectionisnowusedtosupportthecatalyticconverter'soxidationreaction,andtoreduceemissionswhenanengineisstartedfromcold.Afteracoldstart,anengineneedsafuel-airmixturericherthanwhatitneedsatoperatingtemperature,andthecatalyticconverterdoesnotfunctionefficientlyuntilithasreacheditsownoperatingtemperature.Theairinjectedupstreamoftheconvertersupportscombustionintheexhaustheadpipe,whichspeedscatalystwarmupandreducestheamountofunburnedhydrocarbonemittedfromthetailpipe.
(2)Exhaustgasrecirculation
IntheUnitedStatesandCanada,manyenginesin1973andnewervehicles(1972andnewerinCalifornia)haveasystemthatroutesameteredamountofexhaustintotheintaketractunderparticularoperatingconditions.Exhaustneitherburnsnorsupportscombustion,soitdilutestheair/fuelchargetoreducepeakcombustionchambertemperatures.This,inturn,reducestheformationofNOx.
(3)Catalyticconverter
Thecatalyticconverterisadeviceplacedintheexhaustpipe,whichconvertshydrocarbons,carbonmonoxide,andNOxintolessharmfulgasesbyusingacombinationofplatinum,palladiumandrhodiumascatalysts.
3.Evaporativeemissionscontrol
Evaporativeemissionsaretheresultofgasolinevaporsescapingfromthevehicle'sfuelsystem.Since1971(1970inCalifornia),allU.S.vehicleshavehadfullysealedfuelsystemsthatdonotventdirectlytotheatmosphere;mandatesforsystemsofthistypeappearedcontemporaneouslyinotherjurisdictions.Inatypicalsystem,vaporsfromthefueltankandcarburetorbowlvent(oncarburetedvehicles)areductedtocanisterscontainingactivatedcarbon.Thevaporsareadsorbedwithinthecanister,andduringcertainengineoperationalmodesfreshairisdrawnthroughthecanister,pullingthevaporintotheengine,whereitburns.
4.Emissiontesting
In1966,thefirstemissiontestcyclewasenactedintheStateofCaliforniameasuringtailpipeemissionsinPPM(partspermillion).
SomecitiesarealsousingatechnologydevelopedbyDr.DonaldStedmanoftheUniversityofDenver,whichuseslaserstodetectemissionswhilevehiclespassbyonpublicroads,thuseliminatingtheneedforownerstogotoatestcenter.Stedman'slaserdetectionofexhaustgasesiscommonlyusedinmetropolitanareas.
Useofemissiontestdata
Emissiontestresultsfromindividualvehiclesareinmanycasescompiledtoevaluatetheemissionsperformanceofvariousclassesofvehicles,theefficacyofthetestingprogramandofvariousotheremission-relatedregulations(suchaschangestofuelformulations)andtomodeltheeffectsofautoemissionsonpublichealthandtheenvironment.Forexample,theEnvironmentalWorkingGroupusedCaliforniaASMemissionsdatatocreatean"AutoAsthmaIndex"thatratesvehiclemodelsaccordingtoemissionsofhydrocarbonsandnitrogenoxides,chemicalprecursorstophotochemicalsmog.
5.Seealso
(1)Vehicleinspection
Vehicleinspectionisaproceduremandatedbynationalorsubnationalgovernmentsinmanycountries,inwhichavehicleisinspectedtoensurethatitconformstoregulationsgoverningsafety,emissions,orboth.Inspectioncanberequiredatvarioustimes,e.g.,periodicallyorontransferoftitletoavehicle.Ifrequiredperiodically,itis
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