簡介：JOURNALOFMATERIALSSCIENCE15198018231831THEMECHANICALPROPERTIESOFEPOXYRESINSPART2EFFECTOFP/ASTICDEFORMATIONUPONCRACKPROPAGATIONSALFMYAMINI,ROBERTJYOUNGDEPARTMENTOFMATERIALS,QUEENMARYCOLLEGE,MILEENDROAD,LONDONE14NS,UKCRACKPROPAGATIONINASERIESOFEPOXYRESINSDESCRIBEDINPART1HASBEENSTUDIEDASAFUNCTIONOFTESTINGRATEANDTEMPERATUREITHASBEENFOUNDTHATCRACKPROPAGATIONISCONTINUOUSATLOWTEMPERATURESBUTTHATASTHETEMPERATUREISRAISEDTHEMODEOFPROPAGATIONBECOMESUNSTABLESTICK/SLIPFEATURESONTHEFRACTURESURFACESATTHECRACKARRESTLINESHAVEBEENSHOWNTOBEOFTHESAMEDIMENSIONSASTHOSEEXPECTEDFORADUGDALEPLASTICZONEITHASBEENSUGGESTEDTHATTHE“SLIP“PROCESSTAKESPLACEBYSLOWGROWTHOFACRACKTHROUGHTHEPLASTICZONEFOLLOWEDBYRAPIDPROPAGATIONTHROUGHVIRGINMATERIALITHASBEENSHOWNTHATTHESTICK/SLIPBEHAVIOURISDUETOBLUNTINGOFTHECRACKWHICHISCONTROLLEDBYTHEYIELDBEHAVIOUROFTHERESINAUNIQUEFRACTURECRITERIONHASBEENSHOWNTOBEAPPLICABLETOEPOXYRESINSWHICHISTHATACRITICALSTRESSOFTHEORDEROFTHREETIMESTHEYIELDSTRESSMUSTBEACHIEVEDATACRITICALDISTANCEAHEADOFTHECRACKELECTRONMICROSCOPEREPLICASOFTHEFRACTURESURFACESHAVEBEENOBTAINEDANDANUNDERLYINGNODULARSTRUCTURECANBERESOLVEDHOWEVER,NODIRECTCORRELATIONBETWEENTHENODULESIZEANDFRACTUREPROPERTIESHASBEENFOUND1INTRODUCTIONTHEREISCURRENTLYAGREATDEALOFINTERESTINTHEMECHANISMSOFCRACKPROPAGATIONINBRITTLEPOLYMERSTHEGENERALSUBJECTOFCRACKPROPAGATIONINTHERMOSETTINGPOLYMERSHASBEENREVIEWEDRECENTLYBYONEOFTHEAUTHORS1ANDTHISPARTICULARPAPERISCONCERNEDWITHTHEPROPAGATIONOFCRACKSINEPOXYRESINSINCERTAINPOLYMERSSUCHASPOLYMETHYLMETHACRYLATEPMMACRACKSTENDTOPROPAGATEINASTABLE,CONTINUOUSWAYTHROUGHACONSTANTCRACKOPENINGDISPLACEMENT8CCRITERION2,3,WHEREASINOTHERPOLYMERSSUCHASEPOXYRESINS4,CRACKPROPAGATIONTENDSTOOCCURINANUNSTABLESTICK/SLIPMANNERITISKNOWN5THATUNSTABLEPROPAGATIONISSUPPRESSEDINEPOXYRESINSIFTHECRACKSAREPROPAGATEDATLOWTEMPERATURES,WHENTHEMATERIALISWELLBELOWITSTGITHASBEENSHOWNRECENTLY6THATUNDERTHESECONDITIONSACONSTANT6ECRITERIONALSOHOLDSFORANEPOXYRESINITHASBEENRECOGNIZEDFORSEVERALYEARSTHATTHEREISARELATIONSHIPBETWEENTHECRACKPROPAGATIONBEHAVIOURANDTHEPLASTICFLOWPROPERTIESOFANEPOXYRESIN6,7BUTITISONLYVERYRECENTLYTHAT00222461/80/0718230950290/0QUANTITATIVETHEORIESHAVEBEENDEVELOPEDTOACCOUNTFORTHISRELATIONSHIPFOLLOWINGASUGGESTIONFROMWILLIAMS8,THEAUTHORSHAVEBEENABLETOSHOWTHATSTICK/SLIPPROPAGATIONINONEPARTICULAREPOXYRESINSYSTEMCOULDBEEXPLAINEDTHROUGHACRACKBLUNTINGMECHANISM9THESAMEAPPROACHHASBEENDEVELOPEDMOREFORMALLYBYKINLOCHANDWILLIAMS10WHOFOUNDTHATTHECRACKBLUNTINGMECHANISMCOULDSUCCESSFULLYEXPLAINTHEMODESOFCRACKPROPAGATIONINAWIDEVARIETYOFEPOXYRESINSTHEPLASTICDEFORMATIONOFASERIESOFEPOXYRESINSHASBEENCAREFULLYINVESTIGATEDINPART1ANDEXPLAINEDINTERMSOFCURRENTTHEORIESOFPLASTICDEFORMATIONINGLASSYPOLYMERSINTHISSECONDPAPERTHERELATIONSHIPBETWEENTHEFLOWBEHAVIOURANDCRACKPROPAGATIONHASBEENANALYSEDINDETAILASAFUNCTIONOFTHEAMOUNTOFCURINGAGENTUSEDWITHTHERESINANDPOSTCURETEMPERATURE2EXPERIMENTALTHEEPOXYRESINUSEDINTHISSTUDYWASEPIKOTE828HARDENEDWITHDIFFERENTAMOUNTSOFTRIETHYLENETETRAMINETETAANDCUREDFOR3HATDIF?91980CHAPMANANDHALTLTD1823FIGURE2FRACTURESURFACESOFANEPOXYRESINCUREDWITH98PHRTETATHESPECIMENWASPOSTCUREDAT50CFOR3HANDTESTEDATACROSSHEADSPEEDOF005MMRAINAT22CAOPTICALMICROGRAPHOFSURFACEBEMREPLICAOFCRACKARRESTLINECRACKGROWTHDIRECTIONINDICATEDBYARROWSATROOMTEMPERATUREFIG3ASHOWSTHATTHESPECIMENHASAFINEARRESTLINETHEELECTRONMICROGRAPHINFIG3BSHOWSTHEARRESTLINEATAHIGHERMAGNIFICATIONITCANBESEENTHATTHESTRUCTUREISAGAINSTREAKEDANDTHEARRESTLINECORRESPONDSTOANABRUPTCHANGEINDIRECTIONOFTHESTREAKSTHEREAPPEARSTOBEANUNDERLYINGNODULARSTRUCTUREOFTHESCALEOF500AAGOODEXAMPLEOFABROADERTYPEOFCRACKARRESTLINEISGIVENINFIG4ATHISTYPEOFFEATUREISTYPICALOFWELLCUREDSPECIMENSFRACTUREDATTEMPERATURESCLOSETOTG7THEFRACTURESURFACEISFEATURELESSUNTILTHECRACKARRESTPOINTAFTERCRACKARRESTTHEREISASLOWGROWTHREGION13OFCLOSELYSPACEDSTRIATIONSPARALLELTOTHECRACKGROWTHDIRECTIONFOLLOWINGTHESLOWGROWTHREGIONTHEREISAROUGHERHACKLEDREGIONWHERETHECRACKACCELERATESDURINGTHE“SLIP“PROCESSEXAMINATIONOFTHEFRACTURESURFACEBYEMREPLICASHASSHOWNTHATTHESMOOTHAREASOFSUCHSPECIMENSARERELATIVELYFEATURELESSINCONTRASTTOTHESLOWGROWTHREGIONWHICHISSHOWNINFIG4BINTHISAREATHEREAREVSHAPEDFEATURESWHICHAPPEARTOBECAUSEDBYTHECRACKPROPAGATINGONDIFFERENTLEVELSITWASNOTPOSSIBLETORESOLVEANYUNDERLYINGNODULARSTRUCTUREONTHESPECIMENUSEDINFIG433SLOWGROWTHREGIONITWASPOINTEDOUTINTHEPREVIOUSSECTIONTHATINWELLCUREDSPECIMENSFRACTUREDATHIGHTEMPERATURESTHEREISACHARACTERISITCREGIONOFSLOWCRACKGROWTHWHICHWASFIRSTIDENTIFIEDBYPHILLIPSETAL13ITISFOUNDTHATTHESIZEOFTHISREGION,/R,INCREASESASTHETEMPERATUREOFTESTINGISRAISEDTHISCANBESEENCLEARLYINFIG5FORARESINCONTAINING14TPHRTETA,WHEREMICROGRAPHSAREGIVENFORSPECIMENSWHICHHAVEBEENFRACTUREDATTWODIFFERENTTEMPERATURESITWASSHOWNINFIG1THATFORTHISFORMULATIONTHECRITICALSTRESSINTENSITYFACTORFORCRACKINITIATIONKXCIALSOINCREASESFIGURE3FRACTURESURFACEOFANEPOXYRESINCUREDWITH98PHRTETATHESPECIMENWASPOSTCUREDAT100CFOR3HANDTESTEDATACROSSHEADSPEEDOF005MMMINAT22CAOPTICALMICROGRAPHOFFRACTURESURFACEBEMREPLICAOFCRACKARRESTLINECRACKGROWTHDIRECTIONINDICATEDBYARROWS1825

簡介：UNDERSTANDINGHEATTRANSFERMECHANISMSDURINGTHECOOLINGPHASEOFBLOWMOLDINGUSINGINFRAREDTHERMOGRAPHYABENDADAA,,FERCHIQUIB,AKIPPINGCANATIONALRESEARCHCOUNCILOFCANADA,INDUSTRIALMATERIALSINSTITUTE,75DEMORTGANE,BOUCHERVILLE,QUE,CANADAJ4B6Y4BUNIVERSITYOFQUEBECINABITIBITEMISCAMINGUE,445UNIVERSITE′BLVD,ROUYNNORANDA,QUE,CANADAJ9X5E4CUNIVERSITYOFSIEGEN,PAULBONATZSTRASSE911,SIEGEN57068,GERMANYRECEIVED15JUNE2004ACCEPTED25NOVEMBER2004AVAILABLEONLINE24FEBRUARY2005ABSTRACTTHECOOLINGPHASEOFTHEEXTRUSIONBLOWMOLDINGPROCESSHASALARGEINFLUENCEONTHECYCLETIMEOFTHEPROCESSASWELLASONTHEPROPERTIESANDQUALITYOFTHEMOLDEDPRODUCTSABETTERUNDERSTANDINGOFTHEHEATTRANSFERMECHANISMSOCCURRINGDURINGTHECOOLINGPHASEWILLHELPINTHEOPTIMIZATIONOFBOTHMOLDCOOLINGCHANNELSANDOPERATINGCONDITIONSACONTINUOUSEXTRUSIONBLOWMOLDINGMACHINEANDARECTANGULARBOTTLEMOTOROILTYPEMOLDWEREUSEDTOPRODUCEBOTTLESAHIGHDENSITYPOLYETHYLENEHDPEANDAMETALLOCENEPOLYETHYLENEMPEHAVINGDIFFERENTRHEOLOGICALPROPERTIESWERETESTEDMELTANDMOLDTEMPERATURES,COOLINGTIME,INFLATINGPRESSUREANDDIEGAPWEREVARIEDSYSTEMATICALLYANINFRAREDCAMERAWASUSEDTOMEASURETHETEMPERATUREDISTRIBUTIONOFTHEPLASTICPARTJUSTAFTERMOLDOPENINGASWELLASAFTERPARTEJECTIONTHEWALLTHICKNESSANDDIMENSIONSOFTHEBOTTLESOFTHEFINISHEDPARTSWEREMEASUREDINORDERTODETERMINETHESHRINKAGEANDWARPAGEFINALLY,THEINFRAREDTEMPERATUREFINGERPRINTSWEREUSEDTOEXPLAINWHATHAPPENSDURINGTHECOOLINGPHASEANDCORRELATEDWITHTHEFINALPARTCHARACTERISTICSCROWNCOPYRIGHTQ2005PUBLISHEDBYELSEVIERLTDALLRIGHTSRESERVEDKEYWORDSBLOWMOLDINGCOOLINGINFRAREDTHERMOGRAPHYPOLYMERPROCESSING1INTRODUCTIONINTHEEXTRUSIONBLOWMOLDINGOFMEDIUMSIZEBOTTLES,THECOOLINGSTAGEREPRESENTSASUBSTANTIALPARTOFTHEOVERALLCYCLEANDHASAPROFOUNDEFFECTONTHEMICROSTRUCTUREDEVELOPMENTANDONTHEULTIMATEPROPERTIESOFTHEMOLDEDARTICLEDURINGTHECOOLINGOFTHEBLOWNPARTWHILSTINTHEMOLD,HEATISREMOVEDBOTHBYFORCEDCONVECTIONPOLYMER/AIRINTERFACEATTHEINTERNALWALLANDCONDUCTIONPOLYMER/METALINTERFACEATTHEMOLDWALLONCETHEMOLDOPENS,THEPARTWILLCONTINUETOCOOLFROMBOTHSURFACESBYNATURALCONVECTIONSEVERALAUTHORS1–4HAVEDEVELOPEDNUMERICALALGORITHMSFORTHEPREDICTIONSOFTHETEMPERATUREPROFILESINTHEPARTSTHEIREFFORTSHAVEBEENOFLIMITEDVALUEDUETOTHEUNCERTAINTYINTHEVALUESOFHEATTRANSFERCOEFFICIENTSUSEDTOREPRESENTTHEDIFFERENTHEATTRANSFERMECHANISMSFORTHESEREASONSINFRAREDTHERMOGRAPHYPRESENTSITSELFASACOMPLEMENTARYTECHNIQUECAPABLEOFMAPPINGTHETHERMALHISTORYOFBLOWMOLDEDPARTSDURINGTHEDIFFERENTSTAGESOFTHECOOLINGPROCESS5–72EXPERIMENTALSETUPTHEPARAMETRICSTUDYWASDONEONACONTINUOUSEXTRUSIONBLOWMOLDINGMACHINEBATTENFELDFISCHERFBZ1000,EQUIPPEDWITHAMOTOROILTYPEBOTTLEMOLDTHEMOLDISMODULARANDHASFIVEINTERCHANGEABLEPARTSTHECAVITYISMADEOFATOPBLOCK,AMIDDLEBLOCKANDABOTTOMBLOCK,EACHWITHITSOWNCOOLINGCIRCUITTHETHREEBLOCKSAREMOUNTEDONTOABACKPLATEANDWITHINTHEMIDDLEBLOCKANEXCHANGEABLEINSERTISLOCATEDFIG1THEMOLDCAVITYHASAHEIGHTOF220MM,AWIDTHOF100MMANDADEPTHOF50MMINTHISSTUDY,AFLATINSERTWASUSEDINTHEMIDDLEBLOCKTOENSUREACOMPLETECONTACTBETWEENPLASTICANDMOLDADIVERGINGDIEFZ30MMWASUSEDINTHISSTUDY09638695/SEEFRONTMATTERCROWNCOPYRIGHTQ2005PUBLISHEDBYELSEVIERLTDALLRIGHTSRESERVEDDOI101016/JNDTEINT200411007NDTFAXC14506415106EMAILADDRESSAKIMBENDADAIMICNRCNRCGCCAABENDADADOW/POLISUR70055LANDANENHANCEDPOLYETHYLENEMPEPRODUCEDUSINGMETALLOCENETECHNOLOGYDOWELITE5100THEBASICMATERIALPROPERTIESAREGIVENINTABLE1DUETOTHEDIFFERENTMOLECULARSTRUCTUREOFTHEMATERIALS,DIFFERENTPARISONSWELLANDSAGGINGBEHAVIORDURINGEXTRUSIONISEXPECTEDACRUDEESTIMATIONOFTHISBEHAVIORWASOBTAINEDBYMEASURINGTHEDIAMETERANDTHICKNESSOFTHEEXTRUDEDPARISONS,BOTHCLOSETOTHEDIEANDATTHEBOTTOMOFTHEPARISONACOMPARISONOFTHECROSSSECTIONOFTHEPARISONSATTHETOPANDATTHEBOTTOMISSHOWNINFIG3FORHDPEANDMPE,RESPECTIVELYHDPESWELLSCONSIDERABLYANDALSOAPPEARSTOHAVELOWMELTSTRENGTHTHISRESULTSINAPARISONHAVINGAWALLTHICKNESSDISTRIBUTIONALONGITSLENGTHONTHEOTHERHAND,THEMPEEXHIBITSLOWERSWELLANDLOWMELTSTRENGTH,WHICHRESULTSPARADOXICALLYINAPARISONHAVINGAMOREUNIFORMTHICKNESSALONGITSLENGTHTHESEDIFFERENCESWILLHAVEASTRONGINFLUENCEONTHEABSOLUTEANDTHICKNESSDISTRIBUTIONSVALUESINTHEBLOWPARTANDCONSEQUENTLYONITSCOOLINGBEHAVIOR4PROCESSINGPARAMETERSASIMPLEDESIGNOFEXPERIMENTSSCHEMEWASUSEDTOVARYTHEPROCESSINGPARAMETERSDURINGTHEVARIATIONOFONEOFTHEDESCRIBEDPARAMETERS,ALLOTHERPARAMETERSWEREKEPTCONSTANTATTHEIRMEANVALUEASUMMARYOFTHERANGEOFPARAMETERVARIATIONISGIVENINTABLE2DUETOTHEDIFFERENTMATERIALBEHAVIOR,DIFFERENTMELTTEMPERATURESANDCOOLINGTIMESWERECHOSENFORTHEHDPEANDTHEMPETHETEMPERATUREOFTHEHDPEMELTISVARIEDBETWEEN220AND2408C,WHILEFORTHEMPEMELTA190–2108CTEMPERATURERANGEWASUSEDINTHECASEOFTHEBLOWINGTIMES,THESEWEREVARIEDASFOLLOWSHDPE10,15AND20SMPE5,8AND11STHELOWERTEMPERATURESANDSHORTERCOOLINGTIMESWEREUSEDINORDERTOACCOMMODATETHESHORTERDROPTIMESOFTHEMPETHEMOLDTEMPERATUREISCONTROLLEDTHROUGHTHEVARIATIONOFTHEFLOWRATEANDTEMPERATUREOFTHECOOLINGLIQUIDTHESETEMPERATURESWERESETAT4,10AND218CTHEACTUALMOLDTEMPERATUREWASMEASUREDBYUSINGATHERMOCOUPLEINSERTEDFLUSHWITHTHEMOLDSURFACETHEDIEGAPISALSOCHANGEDWITHTHECONTROLUNITOFTHEMACHINEBYTHEUSEOFASERVOCYLINDER,THEMANDRELWITHINTHEDIECANBEMOVEDAXIALLYBECAUSETHEMANDRELHASACONICALSHAPE,THEDIEGAPCHANGESBY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簡介：INTERNATIONALSYMPOSIUMCOULSONANDBROMLEY,1990GISHASLONGBEENACCEPTEDASTHEMOSTAPPROPRIATESOLUTIONTOADDRESSSPATIALLYREFERENCEDDATATHEESSENCEOFGISINTHEPLANMAKINGPROCESS,QUOTINGCALKINS1972,SUGGESTEDTHAT‘BETTERPLANNINGWILLBEACHIEVEDTHROUGHBETTERINFORMATION,ANDBETTERINFORMATIONWILLNECESSARILYFLOWFROMANINFORMATIONSYSTEM’HOWEVER,GISALONECANNOTSERVEALLTHENEEDSOFPLANNINGBECAUSETHECURRENTGENERATIONOF“GENERALPURPOSE”SYSTEMSCANNOTEASILYACCOMMODATETHEPARTICULARINFORMATIONAL,COMPUTATIONAL,ANDDISPLAYNEEDSOFPLANNINGCLEARLY,PLANNINGREQUIRESIINFORMATIONTHATISEFFECTIVELY“ASPATIAL”ATAPARTICULARLEVELOFANALYSISIIINFORMATIONOVERTIMEANDIIIMEASURESOFSPATIALINTERACTIONNONEOFTHISCANBEEASILYINCORPORATEDINTOSTANDARDGISPACKAGESHARRISANDBATTY,199332PLANNINGSUPPORTSYSTEMANDDECISIONSUPPORTSYSTEMGISISAPARTOFTHEPLANNINGSUPPORTSYSTEMSPSS,WHICHALONECANSUPPORTDECISIONMAKINGANDURBANPROBLEMSOLVINGTOACONSIDERABLEEXTENTHOWEVER,PLANNERSWILLHAVETOADAPTEXISTINGGISTOOLSTOMEETTHEIRNEEDSTRADITIONALPROGRAMMINGLANGUAGESCANBEUSEDTODEVELOPSPATIALANALYSISANDMODELLINGTOOLSENTIRELYINDEPENDENTOFCOMMERCIALPACKAGESACOMBINATIONOFSOPHISTICATEDGISMACROCOMMANDSANDTRADITIONALPROGRAMMINGLANGUAGECANALSOBEUSEDTODEVELOPANALYTICALMODELSCLOSELYLINKEDTOFULLFEATUREDGISTOOLKITSKLOSTERMAN,2001THEPSSWHICHISACOMBINATIONOFGISDATA,URBANMODELANDPRESENTATIONTECHNIQUEUSINGCOMPUTERFORPLANNINGSUPPORTHASBEENINCREASINGINUSEFORMOREENHANCEDENDPRODUCTSTHEINEVITABLEEVOLVEMENTOFINFORMATIONTECHNOLOGYTOWARDSPSSMEANSTHATTHEEXPLOITATIONOFGISISMORESIGNIFICANTGISWILLSERVEFIRSTASADISPLAYANDCOMMUNICATIVEDEVICE,PRODUCINGMAPSANDCHARTSTHATDESCRIBEPASTANDPRESENTCONDITIONSANDMODELOUTPUTSTHATSUGGESTALTERNATIVEFUTURES,WHICHSUPPORTDECISIONMAKINGONTOPOFTHAT,THEDECISIONSUPPORTSYSTEMDSSISALSOKNOWNASASYSTEMINWHICHDECISIONMAKERSCOULDRELYONINMAKINGDECISIONS3

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簡介：IEEETRANSACTIONSONPOWERELECTRONICS,VOL8,NO4,OCTOBER1993347HIGHENERGYPULSESWITCHINGCHARACTERISTICSOFTHYRISTORSVENKATESWARAASANKARAN,MEMBER,IEEE,JERRYLHUDGINS,SENIORMEMBER,IEEE,ANDWILLIAMMPORTNOY,FELLOW,IEEEABSTRACTEXPERIMENTSWERECONDUCTEDTOSTUDYTHEHIGHENERGY,HIGHDILDTPULSESWITCHINGCHARACTERISTICSOFSCRSWITHANDWITHOUTTHEAMPLIFYINGGATEHIGHDILDTHIGHENERGYSINGLESHOTEXPERIMENTSWEREFIRSTDONEDEVICESWITHOUTTHEAMPLIFYINGGATEPERFORMEDMUCHBETTERTHANTHEDEVICESWITHTHEAMPLIFYINGGATEAPHYSICALMODELISPRESENTEDTODESCRIBETHEROLEOFTHEAMPLIFYINGGATEINTHETURNONPROCESS,THEREBYEXPLAININGTHEDIFFERENCESINTHESWITCHINGCHARACTERISTICSTHETURNONAREAFORTHEFAILUREOFTHEDEVICESWASTHEORETICALLYESTIMATEDANDCORRELATEDWITHOBSERVATIONSTHISALLOWEDCALCULATIONOFTHECURRENTDENSITYREQUIREDFORFAILURESINCETHEFAILUREOFTHESEDEVICESUNDERHIGHDILDTCONDITIONSWASTHERMALINNATURE,ASIMULATIONUSINGAFINITEELEMENTMETHODWASPERFORMEDTOESTIMATETHETEMPERATURERISEINTHEDEVICESTHERESULTSFROMTHISSIMULATIONSHOWEDTHATTHETEMPERATURERISEWASSIGNIFICANTLYHIGHERINTHEDEVICESWITHTHEAMPLIFYINGGATETHANINTHEDEVICESWITHOUTTHEAMPLIFYINGGATEFROMTHESERESULTS,THESAFEOPERATINGFREQUENCIESFORALLTHEDEVICESUNDERHIGHDILDTCONDITIONSWASESTIMATEDTHESEESTIMATESWERECONFIRMEDBYEXPERIMENTALLYSTRESSINGTHEDEVICESUNDERHIGHDILDTREPETITIVEOPERATIONIINTRODUCTIONECENTINNOVATIONSINSEMICONDUCTORDEVICEDESIGNSRANDADVANCESINMANUFACTURINGTECHNOLOGIESHAVEHELPEDEVOLVEHIGHPOWERTHYRISTORSTHESEDEVICESAREDESIGNEDTOOPERATEINACONTINUOUSMODEFORAPPLICATIONSSUCHASACTODCPOWERCONVERSIONANDMOTORDRIVESUNTILRECENTLY,THEIRAPPLICATIONTOHIGHPOWERPULSESWITCHINGWASMOSTLYUNKNOWNONEOFTHEMAINREASONSTHATHASDISCOURAGEDTHEUSEOFTHYRISTORSFORHIGHSPEED,HIGHENERGYSWITCHINGISTHEIRLOWDILDTRATINGTHELIMITINGVALUEOFTHEDILDTBEFOREDAMAGEOCCURSISRELATEDTOTHESIZEOFTHEINITIALTURNONAREAANDTHESPREADINGVELOCITYIRECENTEXPERIMENTALRESULTSPRESENTEDIN24SHOWTHATWITHINCREASEDGATEDEVICE,SCRSANDGTOSHAVINGHIGHLYINTERDIGITATEDGATECATHODESTRUCTURESCANRELIABLYOPERATEUNDERHIGHDILDTCONDITIONSONASINGLESHOTBASISPREVIOUSLY,SCRSHAVEALSOBEENUSEDFORREPETITIVESWITCHINGOF1KA,10PSWIDEPULSESHAVINGADILDTOFABOUT10000ALPS,AT500AND800HZFORA10HPERIODSIITISREPORTEDIN6THATGTOMODULESFIVEDEVICESINSERIESCANBLOCK115KVANDSWITCH45KAPULSESHAVINGADILDTOF2500A/KSATFREQUENCIESOF100HZASYMMETRICDEVICES,SUCHASTHEASCRSINASTACKASSISTEDBYSATURABLEINDUCTORS,HAVEMANUSCRIPTRECEIVEDAUGUST6,1991REVISEDJULY16,1993VASANKARANISWITHFORDRESEARCHLABORATORY,DEARBOM,M1JLHUDGINSISWITHTHEDEPARTMENTOFELECTRICALANDCOMPUTERENGINEERWMPORTNOYISWITHTEXASTECHNICALUNIVERSITY,LUBBOCK,TXIEEELOGNUMBER9213643ING,UNIVERSITYOFSOUTHCAROLINA,COLUMBIA,SC29208SHOWNTHEPOTENTIALTOREPETITIVELYSWITCHHIGHCURRENTPULSESWITHDI/DTOFABOUT2000ALPS,ONTHEORDEROFKILOHERTZ7UNDERHIGHDILDTCONDITIONSTHEJUNCTIONTEMPERATURESCANVARYRAPIDLYINHIGHPOWERDEVICES106“C/S8THEFAILUREOFTHESEDEVICESUNDERTHESECONDITIONSISNORMALLYTHERMALINNATUREITHASBEENREPORTED9,THATTHETEMPERATUREOFDESTRUCTIONDUETOATUMONDILDTFAILUREISINTHERANGEOFI10013OO0C,BELOWTHEMELTINGPOINTOFSILICON1415°CTHERISEINAVERAGETEMPERATUREISTHEREFORECOMPLETELYINADEQUATEASAMEASUREOFDEVICEAPPLICABILITYFORPULSESWITCHINGAPPLICATIONSSINCEASIMPLEEXPERIMENTALTECHNIQUEISNOTAVAILABLETOMEASURETHEINSTANTANEOUSTEMPERATURERISE,THESPATIOTEMPORALDISTRIBUTIONOFTEMPERATURESINTHEDEVICESHASTOBEESTIMATEDUSINGCOMPUTERAIDEDTECHNIQUESINTHISPAPER,THEHIGHDILDTSINGLESHOTEXPERIMENTALRESULTSAREGIVENINBRIEFAQUALITATIVEPHYSICALMODELISTHENPROPOSEDTOEXPLAINTHEEXPERIMENTALRESULTS,WHICHAREPRESENTEDINDETAILELSEWHERE3NEXT,THERESULTSFROMTHETHERMALANALYSISUSINGFEM,GIVENINDETAILINLO,AREBRIEFLYPRESENTEDTHEPARTICULARSOFTHEEXPERIMENTALARRANGEMENTFORTHEREPETITIVETESTINGOFTHEDEVICES,RESULTSFROMTHESEEXPERIMENTS,ANDTHEIRCORRELATIONWITHTHENUMERICALPREDICTIONSAREGIVENINTHEDISCUSSION11SINGLESHOTEXPERIMENTSINVERTERGRADESCRSWITHTHEAMPLIFYINGGATEUNSHORTEDDEVICEANDWITHOUTTHEAMPLIFYINGGATESHORTEDDEVICEWEREUSEDFOREXPERIMENTALSTUDIESTODETERMINETHEROLEOFTHEAMPLIFYINGGATEDURINGTHETURNONPROCESSESOFTHEDEVICETHESCRSUSEDFORTHETESTSWERESYMMETRICWITHINVOLUTEGATECATHODESTRUCTURESTHEYWERERATEDFORAFORWARDANDREVERSEBLOCKINGVOLTAGEOF24KVAT25°CAND22KVAT125°CTHEEXPERIMENTALDETAILSANDRESULTSAREFULLYPRESENTEDELSEWHERE3THEEXPERIMENTALARRANGEMENTANDTHERESULTSAREGIVENINBRIEFBELOWTHEDEVICESWEREELECTRICALLYCHARACTERIZEDINITIALLYANDRECHARACTERIZEDAFTERTESTINGINATYPEEPULSEFORMINGNETWORKPFNTHATHASATOTALIMPEDANCEOF010THISNETWORKDELIVERSA15KA,10PSWIDEPULSEWHENCHARGEDTOAVOLTAGEOF25KVTHEDI/DTOFTHIS15KAPULSEIS125000ALPSTHEGATETRIGGERUSEDFORSWITCHINGTHESCRSWASA100A,500NSTRAPEZOIDALCURRENTPULSETHEDI/DTOFTHEGATEPULSEWAS980ALPSTHEUNSHORTEDDEVICESFAILEDWHILESWITCHINGAPEAKANODECURRENTOF105KAATADILDTOFABOUT26000ALPSINAPFN08858993/93030001993IEEESANKARANETALPULSESWITCHINGCHARACTERISTICSOFTHYRISTORS349AMPLIFYINGPILOTGATECATHODECONTACTGATECONTACTFIG4CROSSSECTIONALVIEWOFTHEUNSHORTEDDEVICECIAICHIFIG6TYPICALICCHI,CH2ANDPOWERLOSSMULTOFTHEUNSHORTEDDEVICECHI40A/DIV,CH220V/DIV,MULT4096W/DIVTIMEBASE100NS/DIVCATHODECONTACTPILOTGATECONTACTII/MAINCATHODEAREASINI2IIMAINIAIPIGATECURRENT1ANDTHEINCREASEINTHEGATECATHODEVOLTAGEVGK,SHOWNINFIG6,CORRESPONDSINTIME,TOTHEPILOTANODECURRENTFLOWTHISSUPPORTSTHEABOVESUGGESTIONTHATTHEANODECURRENTISINITIALLYFORCEDTOFLOWTHROUGHASMALLAREAHIGHRESISTANCENEARTHEPILOTGATECONTACTTHEREFORETHECURRENTDENSITYDURINGPHASEIANDPHASEI1ISVERYHIGHANDLEADSTOACONSIDERABLEINCREASEINTHELOCALTEMPERATUREITWASREPORTEDEARLIERIN9THATFAILURETEMPERATUREOFTHEDEVICEISABOUT1200°CBASEDONTHISTHECONDUCTIONAREAANDTHECURRENTDENSITYFORTHEFAILUREOFTHEDEVICECANBEESTIMATEDASFOLLOWSFIEADIABATICHEATENERGYOFDISSIPATIONINAVOLUMECANBEMATHEMATICALLYRELATEDTOTHETEMPERATURERISEINTHEVOLUMEASGIVENBELOWFIG5CROSSSECTIONALVIEWOFTHESHORTEDDEVICETHEPBASEBYTHENEMITTERWITHACERTAINEMITTERINJECTIONTAKENFORTHISPROCESSISCALLEDTHETRANSITTIMEANDACCUMULATENEARTHEDEPLETIONREGIONTHISNEGATIVECHARGEACCUMULATIONLEADSTOINJECTIONOFHOLESFROMTHEANODEATTHISTIMETHEDEVICETURNSONAFTERACERTAINDELAY,DICTATEDBYTHEPBASETRANSITTIMELL,ANDTHEPILOTANODECURRENT2BEGINSTOFLOWTHROUGHASMALLREGIONNEARTHEPILOTGATECONTACTASSHOWNINFIG4THISFLOWOFPILOTANODECURRENTCORRESPONDSTOTHEINITIALSHARPRISEINTHEANODECURRENTWAVEFORMPHASEISHOWNINFIG1THEDEVICETHENGOESINTOPHASE11,DURINGEFFICIENCYTHESEELECTRONSTRAVERSETHROUGHTHEPBASETIMEEMC,AT1WHEREEISTHEENERGYDISSIPATEDINTHEVOLUME,MISTHEMASSOFTHEVOLUME,C,ISTHEHEATCAPACITYSPECIFICHEATATCONSTANTPRESSUREOFTHEMATERIAL,ANDATISTHETEMPERATURERISEINTHEVOLUMEEQUATION1CANBEMODIFIEDASEPVC,AT2WHICHTHEANODECURRENTREMAINSFAIRLYCONSTANT,SUGGESTINGTHATTHERESISTANCEOFTHEREGIONHASREACHEDITSLOWERLIMITTHISISBECAUSETHEPILOTANODECURRENT2TAKESAFINITETIMETOTRAVERSETHROUGHTHEPBASELATERALLYANDBECOMETHEGATEWHEREPISTHEMASSDENSITYOFTHEMATERIALANDVISTHEVOLUMEOFTHEMATERIALAREAAXTHICKNESSHTHEREFORE,THECONDUCTIONAREAFORFAILURECANBEESTIMATEDASCURRENTFORTHEMAINCATHODEAREAASARESULT,THENEMITTERSSTARTTOINJECTELECTRONS,WHICHTRAVERSETHEPBASEVERTICALLYANDAFTERACERTAINFINITETIMETRANSITTIMEOFTHEPBASE3REACHTHEREGIONTHETIMETAKENBYTHEABOVESAIDSPECIFICHEATISAFUNCTIONOFTEMPERATURE,BUTSATURATESATABOUT140°CSINCETHEFAILURETEMPERATUREIS1000°C,THEVALUEOFVALUESFORTHEPROPERTIESOFSILICONUSEDINTHECALCULATIONSAREGIVENBELOWPROCESSESISTHEREASONFOROBSERVINGTHISCHARACTERISTICPHASETOTHESWITCHINGDELAY,SUGGESTINGTHATTHEPBASETRANSITTIMEISRESPONSIBLEONCETHEMAINCATHODEREGIONTUMSON,THERESISTANCEOFTHEDEVICEDECREASESANDTHEANODECURRENTBEGINSTHEWIDTHOFTHEPHASEIISSPECIFICHEATUSEDFORTHECALCULATIONISITSSATURATEDVALUETHETORISEAGAINTRANSITIONFROMPHASEI1TOPHASE111FROMHEREONTHEPLASMASPREADINGVELOCITYWILLDICTATETHERATEATWHICHTHECONDUCTIONAREAWILLINCREASETHEDIPINTHEP23G/CRN3C,08J/G/“C

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簡介：MEASUREMENT332003109–119WWWELSEVIERCOM/LOCATE/MEASUREMENTDEVELOPMENTOFMINIATURIZEDSEMICONDUCTORFLOWSENSORSA,BBBBFKOHL,RFASCHING,FKEPLINGER,RCHABICOVSKY,AJACHIMOWICZ,CGURBANA¨LUDWIGBOLTZMANNINSTITUTFURBIOMEDIZINISCHEMIKROTECHNIK,WIEN,AUSTRIAB¨INSTITUTFURINDUSTRIELLEELEKTRONIKUNDMATERIALWISSENSCHAFTEN,VIENNAUNIVERSITYOFTECHNOLOGY,GUSSHAUSSTRASSE27–29,A1040WIEN,AUSTRIAC¨¨¨INSTITUTFURMIKROSYSTEMTECHNIK,ALBERTLUDWIGSUNIVERSITATFREIBURG,GEORGEKOHLERALLEE103,D79110FREIBURG,GERMANYACCEPTED8OCTOBER2002ABSTRACTMINIATURIZEDFLOWSENSORSBASEDONTHINFILMGERMANIUMTHERMISTORSWEREDEVELOPEDOFFERINGHIGHFLOWSENSITIVITIESANDSHORTRESPONSETIMESTHETHERMISTORSAREPLACEDONASILICONNITRIDEDIAPHRAGMCARRIEDBYASILICONFRAMEUSINGTHE3CONTROLLEDOVERTEMPERATURESCHEMETHEMEASURABLEAIRFLOWRATERANGESFROM06TO150000CM/HINTHISPAPERWEMAINLYREPORTONTHEDYNAMICPROPERTIESOFTHESENSORTHERESPONSEOFTHESENSORTOSTEPCHANGESOFTHEHEATERPOWERWILLBECOMPAREDWITHITSRESPONSETOSHOCKWAVESFORBOTHTHECONSTANTPOWERMODEANDTHECONSTANTOVERTEMPERATUREOPERATINGMODEASIMPLEARRANGEMENTFORTHEGENERATIONOFACOUSTICSHOCKWAVESWILLBEPRESENTED?2002ELSEVIERSCIENCELTDALLRIGHTSRESERVEDKEYWORDSELECTROCALORIMETRICFLOWMEASUREMENTTHINFILMGERMANIUMTHERMISTORSMICROMACHINEDFLOWSENSOR1INTRODUCTIONTHEENGINE’SFUELCONSUMPTIONANDTHEPOLLUTIONOFTHEENVIRONMENTFORTHEDEVELOPMENTOFSUCHENTHEREISAGROWINGDEMANDOFMICROFLOWSENSORSGINESAWIDEVELOCITYMEASURINGRANGEANDHIGHFORINDUSTRIAL,AUTOMOTIVE,DOMESTICANDMEDICALRESOLUTIONMONITORINGOFTHETIMECOURSEOFTHEAIRAPPLICATIONSTHEMEASURINGPRINCIPLECANBEBASEDVELOCITYISDESIRABLEONTHERMISTORS,THERMOPILES,PYROELECTRICELEMENTS,THEELECTROCALORIMETRICFLOWSENSORPRESENTEDHEREPNJUNCTIONS,RESONATINGMICROBRIDGES,PRANDTLTUBESISBASEDONAHEATTRANSFERPRINCIPLEINWHICHAANDSEVERALOTHEREFFECTS1–10MICROMACHININGISHEATEDBODYISCOOLEDBYAPASSINGFLOWANDTHELOCALADOPTEDTOACHIEVEHIGHSENSITIVITY,QUICKRESPONSERATEOFCOOLINGDEPENDSONTHEFLOWVELOCITY11ANDLOWPOWERCONSUMPTIONTHESENSORISBASEDONTHESOCALLED‘HOTFILM’FLOWONEIMPORTANTAPPLICATIONOFFLOWSENSORSISTHEMEASUREMENTMETHODAVERYTHINSILICONNITRIDEMEASURINGOFTHEINSTANTANEOUSAIRINTAKEOFCOMBUSDIAPHRAGMSUPPORTEDBYAMICROMACHINEDSILICONTIONENGINESKNOWLEDGEOFTHISCOMBUSTIONPROCESSFRAMEISMOUNTEDFLUSHWITHTHEWALLOFAFLOWPARAMETERISESSENTIALIFONETRIESTOMINIMIZEBOTHCHANNELASSHOWNINFIG1ATHINFILMHEATINGRESISTORISEMBEDDEDINTHEDIAPHRAGMTOOBTAINACORRESPONDINGAUTHORSYMMETRICSURFACETEMPERATUREDISTRIBUTIONTWO02632241/02/–SEEFRONTMATTER?2002ELSEVIERSCIENCELTDALLRIGHTSRESERVEDPIIS0263224102000581FKOHLETAL/MEASUREMENT332003109–119111BOTHSILICONNITRIDELAYERSFORMTHEDIAPHRAGMOFTHEMICROMACHINEDSENSORSILICONNITRIDEEXHIBITSALOWTHERMALCONDUCTIVITYRESULTINGINHIGHFLOWSENSITIVITYTHETHERMALCONDUCTIVITYOFSILICONNITRIDEISABOUT23W/MKASCOMPAREDTO150W/MKFORSILICONAFURTHERADVANTAGEOFTHESILICONNITRIDEDIAPHRAGMISITSSMALLTHICKNESSRESULTINGINASMALLTHERMALCONDUCTIONTHE800NMTHICKDIAPHRAGMUSEDINOURSENSORHASBEENPROVEDTOBEVERYSTABLEINATANGENTIALFLOWFIG2AMORPHOUSGERMANIUMEXHIBITSHIGHVALUESOFFIG3SCHEMATICTOPVIEWOFTHETHINFILMSTRUCTURESONTHESENSORDIAPHRAGMTWOLAYOUTSWITHINTERDISTANCESBETWEENHEATERBOTHTHERESISTIVITYANDITSTEMPERATURECOEFFICIENTANDDIAPHRAGMTEMPERATURESENSORSOF35AND100MMWERETHETEMPERATURECOEFFICIENTOFRESISTANCETCRISREALIZEDAPPROXIMATELY22/KANDTHERESISTIVITYISABOUT5VMATROOMTEMPERATUREMEASUREMENTSOFTHETEMPERATUREDEPENDENCEOFTHETHERMISTORRESISTANCEPOWERISABOUT4MW,WHICHCORRESPONDSTOAHEATERBETWEEN77AND330KREVEALED,THATTHEELECTRICALVOLTAGEOF3VBOTHPLATINUMANDNICHROMEHAVECONDUCTIVITYOFAMORPHOUSGERMANIUMISGOVERNEDBEENAPPLIEDASTHEHEATERMATERIALBYAVARIABLERANGEHOPPINGPROCESS14ATROOMFURTHERMORE,NARROWPAIRTOLERANCESOFTHETHERTEMPERATURETHETCRVARIESONLYSLIGHTLYWITHTEMMISTORCHARACTERISTICSAREIMPORTANTTOACHIEVEHIGHPERATURE,WHICHEASESAPPRECIABLETHEBURDENFORRESOLUTIONINTEMPERATUREDIFFERENCEMEASUREMENTSCOMPENSATINGOFCHANGESOFTHEAMBIENTTEMPERATURENONETHELESSAHIGHPRECISIONOFTHESENSORGEOMETRYALAYOUTASSHOWNINFIG3ANDA250NMTHICKISNECESSARYFORANOFFSETFREEBIDIRECTIONALSENSORGERMANIUMFILMRESULTINARESISTANCEOF70KVATCHARACTERISTIC208CITHASBEENPROVEDTHATTHELONGTERMSTABILITYBOTHTHEHEATERANDTHETHERMISTORSEXHIBITSMALLOFTHISCHARACTERISTICISBETTERTHAN05PERYEARADIMENSIONSINTHENOMINALFLOWDIRECTIONANDLARGENOISEEQUIVALENTTEMPERATUREDIFFERENCEOF10MKFOREXTENTSPERPENDICULARTOTHISDIRECTIONTHESEEXABANDWIDTHOF10HZISACHIEVEDWITHTHISTHERMISTREMEASPECTRATIOSOFHEATERANDTHERMISTORAREATORTECHNOLOGY10FORCOMPARISON,JOHNSONNOISEWERECHOSENFORFOURREASONSATOACHIEVEAONLYWOULDLIMITTHERESOLUTIONTO475MKPRONOUNCEDDIRECTIONALCHARACTERISTICFORTHEFLOWSENSITIVITY,BTOAVOIDDELAYOFRESPONSEDUETOTHERMALPROPAGATIONTIMES,CTOACHIEVESUITABLERESISTANCEVALUESOFTHETHERMISTORANDTHEHEATER,3EXPERIMENTALANDDTOENSUREAUNIFORMLOCALTEMPERATURETHROUGHOUTTHEAMORPHOUSGERMANIUMAREAUNDER31SENSORMOUNTINGSTATICANDDYNAMICHEATTRANSPORTCONDITIONSFURTHERMORE,DUETOTHEHIGHASPECTRATIOAONETOSTUDYTHESENSORPROPERTIESINSITUATIONSTHATAREDIMENSIONALMODELINGOFHEATCONDUCTIONINTHETYPICALFORVARIOUSAPPLICATIONSTHECHIPWASATTACHEDDIAPHRAGMANDTWODIMENSIONALMODELSFORHEATTODIFFERENTCARRIERCONSTRUCTIONSCONVECTIONARESUFFICIEN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