学科分类
/ 12
224 个结果
  • 简介:Inordertosolvethemagneto-hydrodyna-mics(MHD)problems,itisneccessarytocombineMaxwell'sequationswithfluidmechanicsequations.But,underthefirstorderapproximationthemasspointmotivationequationsandelectromagneticbasiclawsare

  • 标签: MHD 不稳定性 喷气流 流体力学 麦克斯韦方程
  • 简介:Amorphouscarbonandgrapheneco-modifiedLiFePO4nanocompositehasbeensynthesizedviaafacilepolyolprocessinconnectionwithafollowingthermaltreatment.Variouscharacterizationtechniques,includingXRD.Mossbauerspectra,Ramanspectra,SEM,TEM,BET,O2-TPO,galvanocharge-discharge,CVandEISwereappliedtoinvestigatethephasecomposition,carboncontent,morphologicalstructureandelectrochemicalperformanceofthesynthesizedsamples.TheeffectofintroducingwayofcarbonsourcesonthepropertiesandperformanceofLiFePO4/C/graphenecompositewaspaidspecialattention.Underoptimizedsyntheticconditions,highlycrystalizedolivine-typeLiFePO4wassuccessfullyobtainedwithelectronconductiveFe2PandFePasthemainimpurityphases.SEMandTEManalysesdemonstratedthegraphenesheetswererandomlydistributedinsidethesampletocreateanopenstructuredLiFePO4withrespecttographene,whiletheglucosederivedcarbonmainlycoatedoverLiFeP04particleswhicheffectivelyconnectedthegraphenesheetsandLiFePO4particlestoresultinamoreefficientchargetransferprocess.Asaresult,favorableelectrochemicalperformancewasachieved.Theperformanceoftheamorphouscarbon-grapheneco-modifiedLiFePO4wasfurtherprogressivelyimproveduponcyclinginthefirst200cyclestoreachareversiblespecificcapacityashighas97mAh·g-1at10Crate.

  • 标签: 无定形碳 复合材料 多元醇 锂离子电池 石墨 改性
  • 简介:WithvonMisesyieldcriterion,theloadingrangeofNetSectionCollapse(NSC)Criteriaisextendedfromcombinedtensionandbendingloadingstocombinedbending,torsionandinternalpressureloadings.AnewtheoreticalanalyzingmethodofplasticlimitloadforpressurepipewithincompleteweldingdefectsbasedontheextendedNSCCriteriaispresentedandthecorrelativeformulasarededuced,theinfluencesofpipecurvature,circumferentiallengthanddepthofincompleteweldingdefectsontheplasticlimitloadofpressurepipeareconsideredaswellinthismethod.Meanwhile,accordingtotheorthogonalexperimentaldesignmethod,theplasticlimitloadsarecalculatedbythefiniteelementmethodandcomparedwiththetheoreticalvalues.Theresultsshowthattheexpressionsofplasticlimitloadofpressurepipewithincompleteweldingdefectsunderbending,torsionandinternalpressurebasedonextendedNSCcriteriaarereliable.Thestudyprovidesanimportanttheoreticalbasisfortheestablishmentofsafetyassessmentmeasuretowardspressurepipewithincompleteweldingdefects.

  • 标签:
  • 简介:TheLHCDantennathatwillbeusedinHL-2AistheoriginaloneusedinHL-1M,whichwillbemodified.Wemeasuredthefeatureoftheantenna.Thefeaturesincludethereflectionofmainwaveguide,VSWR,theadjacentphrasingbetweenthesub-waveguidesandsoon.Thepaperdescribesthemeasuredresultsandspectrumcalculationbasedonthemeasuredparameters.FromtheworkswecanappreciateourantennacorrectlywhichwillbeusefulforLHCDexperimentonHL-2Aintheyear.

  • 标签: HL-2A LHCD 子波导 多节发射天线阵 波谱 数值计算
  • 简介:Asahighspecificspeedpump,thecontra-rotatingaxialflowpumpdistinguishesitselfinarearrotorrotatingintheoppositedirectionofthefrontrotor,whichremarkablycontributestotheenergyconversion,thereductionofthepumpsize,betterhydraulicandcavitationperformances.However,withtworotorsrotatingreversely,thesignificantinteractionbetweenbladerowswasobservedinourprototypecontra-rotatingrotors,whichhighlyaffectedthepumpperformancecomparedwiththeconventionalaxialflowpumps.Consequently,anewtypeofrearrotorwasdesignedbytherotationalspeedoptimizationmethodologywithsomeadditionalconsiderations,aimingatbettercavitationperformance,thereductionofbladerowsinteractionandthesecondaryflowsuppression.Thenewrearrotorshowedasatisfactoryperformanceatthedesignflowratebutanunfavorablepositiveslopeofthehead-flowratecurveinthepartialflowraterangelessthan40%ofthedesignflowrate,whichshouldbeavoidedforthereliabilityofpump-pipesystems.Inthepresentresearch,tounderstandtheinternalflowfieldofnewrearrotoranditsrelationtotheperformancesatthepartialflowrates,thevelocitydistributionsattheinletsandoutletsoftherotorsarefirstlyinvestigated.Then,theboundarylayerflowsonrotorsurfaces,whichclearlyreflectthesecondaryflowinsidetherotors,areanalyzedthroughthelimitingstreamlineobservationsusingthemulti-coloroil-filmmethod.Finally,theunsteadynumericalsimulationsarecarriedouttounderstandthecomplicatedinternalflowstructuresintherotors.

  • 标签: 旋转速度 设计流量 轴流泵 实验分析 流动结构 转子结构
  • 简介:Inlostpaperofmagneto-hydrodynamicinstabilityanalysisofliquidmetalfreesurfacejetflow(PartⅠ),themagneto-hydrodynamicinstabilitywasanalyzedforthejetflowinatransversenon-uniformmagneticfield,BT.But,asallknown,fortherealconditionsofliquidmetallimiter-divertorplasma-facingcomponentsareintoroidalandpoloidalfields.So,wetrytoanalyzethemagneto-hydrodynamicinstabilityofthejetflow(herebyonlyforcircularshapecrosssectionjetflow)inthezoneofnon-uniformmagneticfields,

  • 标签: 自由表面射流 磁流体动力学 不稳定性 磁聚变 液态金属偏滤器
  • 简介:Structuralhealthmonitoring(SHM)isarelevanttopicforcivilsystemsandinvolvesthemonitoring,dataprocessingandinterpretationtoevaluatetheconditionofastructure,inordertodetectdamage.Inrealstructures,twoormoresitesortypesofdamagecanbepresentatthesametime.Ithasbeenshownthatonekindofdamagedconditioncaninterferewiththedetectionofanotherkindofdamage,leadingtoanincorrectassessmentaboutthestructurecondition.Identifyingcombineddamageonstructuresstillrepresentsachallengeforconditionmonitoring,becausethereliableidentificationofacombineddamagedconditionisadifficulttask.Thus,thisworkpresentsafusionofmethodologies,whereasinglewavelet-packetandtheempiricalmodedecomposition(EMD)methodarecombinedwithartificialneuralnetworks(ANNs)fortheautomatedandonlineidentification-locationofsingleormultiple-combineddamageinascaledmodelofafive-baytruss-typestructure.Resultsshowedthattheproposedmethodologyisveryefficientandreliableforidentifyingandlocatingthethreekindsofdamage,aswellastheircombinations.Therefore,thismethodologycouldbeappliedtodetection-locationofdamageinrealtruss-typestructures,whichwouldhelptoimprovethecharacteristicsandlifespanofrealstructures.

  • 标签: 经验模式分解 桁架式结构 结构损坏 小波包 振动分析 定位
  • 简介:Inthispaper,adetailedLiesymmetryanalysisofthe(2+1)-dimensionalcouplednonlinearextensionofthereaction-diffusionequationispresented.Thegeneralfinitetransformationgroupisderivedviaasimpledirectmethod,whichisequivalenttoLiepointsymmetrygroupactually.Similarityreductionandsomeexactsolutionsoftheoriginalequationareobtainedbasedontheoptimalsystemofone-dimensionalsubalgebras.Inaddition,conservationlawsareconstructedbyemployingthenewconservationtheorem.

  • 标签: (2+1)-dimensional COUPLED nonlinear REACTION-DIFFUSION equation Lie
  • 简介:Thispaperusesfiniteelementmethodtoobtainthethree-dimensionaltemperaturefieldoflaser-inducedtransientthermalgrating(TTG)fortwo-layeredstructureofdiamondfilmonZnSesubstrate.Thenumericalresultsindicatethatuniquetwo-timesheatingprocessisgraduallyexperiencedintheareabetweentwoadjacentgratingstripes.However,thereisalittlechangeforthetemperaturefieldalongthedepthdirectionforthediamondfilmduetoitsgreatthermalconductivity.Itfurtherfindsthatthethicknessofthediamondfilmhasasignificantinfluenceonthetemperaturefieldindiamond/ZnSesystem.Theresultsareusefulfortheapplicationoflaser-inducedTTGtechniqueinfilm/substratesystem.

  • 标签: 金刚石/硒化锌系统 有限元法 热分析 瞬时热光栅 三维激光
  • 简介:Thispaperdiscussesastatisticalsecond-ordertwo-scale(SSOTS)analysisandcomputationforaheatconductionproblemwitharadiationboundaryconditioninrandomporousmaterials.Firstly,themicroscopicconfigurationforthestructurewithrandomdistributionisbrieflycharacterized.Secondly,theSSOTSformulaeforcomputingtheheattransferproblemarederivedsuccessivelybymeansoftheconstructionwayforeachcell.Then,thestatisticalpredictionalgorithmbasedontheproposedtwo-scalemodelisdescribedindetail.Finally,somenumericalexperimentsareproposed,whichshowthattheSSOTSmethoddevelopedinthispaperiseffectiveforpredictingtheheattransferperformanceofporousmaterialsanddemonstratingitssignificantapplicationsinactualengineeringcomputation.

  • 标签: 热传导问题 多孔材料 计算传热 二阶分析 边界条件 统计
  • 简介:AlthoughtheimpactofroadtransportonurbanairqualityhasachievedahighprofileinChina,stillgreaterattentionisrequiredasithasnotyetbeenconsideredfullyeveninrelationtotheroadnetworklinkingcitiesandurbanareas.Strategicenvironmentalassessment(SEA)isasystematicandcomprehensiveprocessforevaluatingtheenvironmentalimpactsofapolicy,planorprograminpubliclyaccountabledecision-making.AirpollutionhasbeenrecognizedasasignificantissueinmosttransportSEApractices.TheStrategicEnvironmentalAssessmentoftheHubeiRoadNetworkPlan(2002-2020)(HRNP)wasintroducedasoneoftheWorldBank'spilotSEAprojects.Aneffectiveframeworkwasdevelopedtoinvestigatethefunctionalrelationshipbetweentheroadnetworkanditspotentialairpollutantemissions.Inthisstudy,twoindicatorswereidentified:emissionintensity/inventoryofpollutantsandthespatialdistributionofthemostpollutedareas.Becausestrategicactionsareinherentlynebulousanddataqualityisoftendisappointing,threealternativescenarioswereemployedtoaddressuncertaintiesanddata/scaleissues.Calculationsweremadeusingemissionmodelsandresultswereanalyzedwiththehelpofstatisticaltoolsandthegeographicinformationsystem(GIS).TheresultsfromtheprojectimplementationandthefeedbackfromtheWorldBankhavebothshownthattheproposedframeworkiseffectiveinthetransportSEAprocess.

  • 标签:
  • 简介:High-temperaturePhaseChangeMaterial(PCM)isusedasathermalstoragemediumofaheat-pipereceiverinanadvancedsolardynamicsystem.Withbothvoidcavityandnaturalconvectionconsidered,thermalperformanceoftheheat-pipereceiverisnumericallyanalyzedundergravity.TheresultsindicatethatthePCMcontainedintheintegratedheatpipeperformsanaveragingfunctionofheatloadings.Thethermalperformanceoftheheat-pipereceiverisstableandreliable.Whenaheatingcycleisstable,thetemperaturefluctuationsbothonheat-pipewallandinPCMcanisterremainlessthan13Kthroughoutasunlightandeclipsecycle.TheutilityofPCMisessentiallyimproved.ThemaximummeltingratioofPCMis92%.Undergravity,PCMmeltsmorequicklywiththeeffectofnaturalconvection.Naturalconvectionacceleratestheprocessofphasechanges.Numericalresultsarecomparedwiththeexperimentalresultsconcerned.Theaccuracyofnumericalmodelundergravityisverified.TheexperimentforthePCMcanisteronthegroundcanbewellpreparedwithournumericalsimulation.

  • 标签: 重力作用 相变材料 瞬态热分析 热管 二维 吸热
  • 简介:Opticalcouplingbehaviorandassociatedeffectsintwo-dimensionalimplant-definedcoherentlycoupledverticalcavitysurface-emittinglaser(VCSEL)arraysarestudiedviabothexperimentsandtheoreticalcalculations.Experimentsshowthatopticalcouplingbetweenarrayelementscanenhancethearray’soutputpower.Additionally,opticalcouplingvialeakyopticalfieldscanprovideextraopticalgainforthearrayelements,whichcanthenreducethethresholdsoftheseelements.Elementscanevenbepumpedwithoutcurrentinjectiontoemitlightbyreceivingastrongleakyopticalfieldfromotherarrayelements.Opticalcouplingcanalsocauseunusualphenomena:thecentralelementsinlarge-areacoherentlycoupledVCSELarraysthatlasepriortotheouterelementswhenthearraysarebiased,ortheaverageinjectioncurrentrequiredforeachelementtolase,whichismuchlowerthanthethresholdforasingleVCSEL.Theoreticalcalculationsareperformedtoexplaintheexperimentalresults.

  • 标签: VCSEL implant-defined VERTICAL-CAVITY SURFACE-EMITTING laser
  • 简介:导致激光的故障光谱学(解放)作为一种强大的分析技术被使用在新鲜植物样品分析踪迹元素。我们调查新鲜冬青叶子的LIBS系列并且观察在区域230-438nm从25个元素和分子射出的超过430根线。用于踪迹元素的半量的分析的解放上的激光波长的影响在植物样品满足被学习。结果证明紫外激光在植物样品为踪迹元素内容的半量的分析有更低的相对标准差和更好的重覆性。这个工作可能对改进解放的力量使用了种样品的定量分析有用。[从作者抽象]

  • 标签: 痕量元素分析 激光诱导 植物样品 激光波长 半定量 光谱