简介：Handlingindustrialpowdersleadstodustemissions.Theseemissionstendtogeneratehumandiseasesorcauseotherenvironmentaleffects.Amultitudeofapparatushasbeendevelopedtoestimatethisdustinessbehaviourofpowders.Twoofthesewell-knownmethodsarepresentedandcomparedwitheachother.Athirdrecentlydevelopedmethodisalsointroduced.

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简介：Basedonelementarygrouptheory,theblockpivotmethodsforsolv-ingtwo-dimensionalelasticfrictionalcontactproblemsarepresentedinthispaper.Itisprovedthatthealgorithmsconvergewithinafinitenumberofstepswhenthefrictioncoefficientis'relativesmall'.Unlikemostmathematicalprogrammingmeth-odsforcontactproblems,theblockpivotmethodspermitmultipleexchangesofbasicandnonbasicvariables.

简介：Inthiswork,dynamiccompositeanalysistruncatedsandwichconicalshells(STCS)withdifferentboundaryconditionsunderlowvelocityimpactwasinvestigatedanalytically,accordinghigherordersandwichpaneltheory.ImpactoccurredatthetopfacesheetandthecontactforcehistoryispredictedusingtwosolutionmodelscalculatedapplyingprincipalofHamiltonbyconsideringthedisplacementcontinuityconditionsbetweenthelayers.Forobtainingthedisplacementandcontactforcehistories,thedifferentialquadraturemethod(DQM)isutilised.Inthisinvestigation,theeffectsoflayerlaminanumber,conesemivertexangle,boundaryconditionsandimpactvelocityontheimpactresponsearestudied.

简介：Inthiswork,dynamiccompositeanalysistruncatedsandwichconicalshells(STCS)withdifferentboundaryconditionsunderlowvelocityimpactwasinvestigatedanalytically,accordinghigherordersandwichpaneltheory.ImpactoccurredatthetopfacesheetandthecontactforcehistoryispredictedusingtwosolutionmodelscalculatedapplyingprincipalofHamiltonbyconsideringthedisplacementcontinuityconditionsbetweenthelayers.Forobtainingthedisplacementandcontactforcehistories,thedifferentialquadraturemethod(DQM)isutilised.Inthisinvestigation,theeffectsoflayerlaminanumber,conesemivertexangle,boundaryconditionsandimpactvelocityontheimpactresponsearestudied.

简介：The6thAsianConferenceonMultibodyDynamics(ACMD2012)hasbeensuccessfullyheldinShanghaiChinaorganizedbyShanghaiJiaoTongUniversity,hostedbytheChineseSocietyofTheoreticalandAppliedMechanics,divisionofdynamicsandcontrol,theJapanSocietyofMechanicalEngineers,theKoreanSocietyofMechanicalEngineers,InternationalFederationforthePromotionofMechanismandMachineScienceandInternationalSteeringCommitteeofAsianConferenceonMultibodyDynamics.

简介：Severaleffectivenumericalmethodsforsolvingtheelasto-plasticcontactproblemswithfrictionarepres-ented.First,adirectsubstitutionmethodisemployedtoimposethecontactconstraintconditionsoncondensedfiniteele-mentequations,thusresultinginareductionbyhalfinthedimensionoffinalgoverningequations.Second,analgorithmcomposedofcontactconditionprobesandelasto-plasticiterationsisutilizedtosolvethegoverningequation,whichdistinguishestwokindsofnonlinearities,andmakesthesolutionunique.Inaddition,Positive-NegativeSequenceModifica-tionMethodisusedtocondensethefiniteelementequationsofeachsubstructureandananalyticalintegrationisintro-ducedtodeterminetheelasto-plasticstatusaftereachtimesteporeachiteration,hencethecomputationalefficiencyisen-hancedtoagreatextent.Finally,severaltestandpracticalexamplesarepressentedshowingthevalidityandversatilityofthesemethodsandalgorithms.

简介：Themulti-scalestructuresofcomplexflowsinchemicalengineeringhavebeengreatchallengestothedesignandscalingofsuchsystems,andmulti-scalemodelingisthenaturalwayinresponse.Particlemethods(PMs)areidealconstituentsandpowerfultoolsofmulti-scalemodels,owingtotheirphysicalfidelityandcomputationalsimplicity.Especially,pseudo-particlemodeling(PPM,Ge&Li,1996;Ge&Li,2003)ismostsuitableformolecularscaleflowpredictionandexplorationoftheoriginofmulti-scalestructures;macro-scalePPM(MaPPM,Ge&Li,2001)andsimilarmodelsareadvantageousformeso-scalesimulationsofflowswithcomplexanddynamicdiscontinuity,whilethelatticeBoltzmannmodelismorecompetentforhomogeneousmediaincomplexgeometries;andmeso-scalemethodssuchasdissipativeparticledynamicsareuniquetoolsforcomplexfluidsofuncertainpropertiesorflowswithstrongthermalfluctuations.Allthesemethodsarefavorableforseamlessinterconnectionofmodelsfordifferentscales.However,asPMsarenotoriginallydesignedaseithertoolsforcomplexityorconstituentsofmulti-scalemodels,furtherimprovementsareexpected.PPMisproposedformicroscopicsimulationofparticle-fluidsystemsasacombinationofmoleculardynamics(MD)anddirectsimulationMonte-Carlo(DSMC).ThecollisiondynamicsinPPMisidenticaltothatofhard-sphereMD,sothatmass,momentumandenergyareconservedtomachineaccuracy.However,thecollisiondetectionprocedure,whichismosttime-consuminganddifficulttobeparallelizedforhard-sphereMD,hasbeengreatlysimplifiedtoaprocedureidenticaltothatofsoft-sphereMD.Actually,thephysicalmodelbehindsuchatreatmentisessentiallydifferentfromMDandismoresimilartoDSMC,butanintrinsicdifferenceisthatinDSMCthecollisionsfollowdesignedstatisticalrulesthatarereflectionoftherealphysicalprocessesonlyinverylimitedcasessuchasdilutegas.PPMisidealforexploringthemechanismofcomplexflowsa

简介：U-shapedmicro-nanochannelscangeneratesignificantflowdisturbanceaswellaslocallyamplifiedelectricfield,whichgivesitselfpotentialtobemicrofluidicmixers,electrokineticpumps,andevencelllysisprocess.NumericalsimulationisutilizedinthisworktostudythehiddencharacteristicsoftheU-shapedmicro-nanochannelsystem,andtheeffectsofkeycontrollingparameters(theexternalvoltageandpressure)onthedeviceoutputmetrics(current,maximumvaluesofelectricfield,shearstressandflowvelocity)wereevaluated.Alargeportionofcurrentflowingthroughthewholesystemgoesthroughthenanochannels,ratherthanthemiddlepartofthemicrochannel,withitsvalueincreasinglinearlywiththeincreaseofvoltage.Duetothelocaliondepletionnearmicro-nanofluidicjunction,significantlyenhancedelectricfield(asmuchas15foldatV=1VandP0=0)aswellasstrongshearstress(leadingtoelectrokineticflow)isgenerated.Withincreasingexternalpressure,bothelectricfieldandshearstresscanbeincreasedinitially(duetoshorteningofdepletionregionlength),butaresuppressedeventuallyathigherpressureduetothedestructionofiondepletionlayer.Insightsgainedfromthisstudycouldbeusefulfordesigningnonlinearelectrokineticpumpsandothersystems.

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简介：Whendesigningawavepowerplant,reliableandfastsimulationtoolsarerequired.Computationalfluiddynamics(CFD)softwareprovideshighaccuracybutwithaveryhighcomputationalcost,andinoperational,moderateseastates,linearpotentialflowtheoriesmaybesufficienttomodelthehydrodynamics.Inthispaper,amodelisbuiltinCOMSOLMultiphysicstosolveforthehydrodynamicparametersofapoint-absorbingwaveenergydevice.TheresultsarecomparedwithalinearmodelwherethehydrodynamicalparametersarecomputedusingWAMIT,andtoexperimentalresultsfromtheLysekilresearchsite.Theagreementwithexperimentaldataisgoodforbothnumericalmodels.

简介：Inthispaper,afullythird-orderaccurateprojectionmethodforsolvingtheincompressibleNavier-Stokesequationsisproposed.Toconstructthescheme,acontinuousprojectionprocedureisfirstlypresented.Wethenderiveasufficientconditionforthecontinuousprojectionequationstobetemporallythird-orderaccurateapproximationsoftheoriginalNavier-Stokesequationsbymeansofthelocaltruncation-error-analysistechnique.Thecontinuousprojectionequationsarediscretizedtemporallyandspatiallytothird-orderaccuracyonthestaggeredgrids,resultinginafullythird-orderdiscreteprojectionscheme.Thepossibilitytodesignhigher-orderprojectionmethodsisthusdemonstratedinthepresentpaper.Aheuristicstabilityanalysisisperformedonthisprojectionmethodshowingtheprobabilityofitsbeingstable.Thestabilityofthepresentschemeisfurtherverifiedthroughnumericaltests.Thethird-orderaccuracyofthepresentprojectionmethodisvalidatedbyseveralnumericaltestcases.

简介：Basedontheclassical(matrixtype)input-outputanalysis,atypeofnonlinear(continuoustype)conditionalLeontiefmodel,input-outputequationwereintroduced,aswellasthreecorrespondingquestions,namely,solvability,continuityandsurjectivity,andsomefixedpointandsurjectivitymethodsinnonlinearanalysiswereusedtodealwiththesequestions.Asaresult,themaintheoremsareobtained,whichprovidesomesufficientcriterionstosolveabovequestionsdescribedbytheboundarypropertiesoftheenterprise'sconsumingoperator.

简介：Aninitial-boundaryvalueproblemforshallowequationsystemconsistingofwaterdynamicsequations,silttransportequation,theequationofbottomtopographychange,andofsomeboundaryandinitialconditionsisstudied,theexistenceofitsgeneralizedsolutionandsemidiscretemixedfiniteelement(MFE)solutionwasdiscussed,andtheerrorestimatesofthesemidiscreteMFEsolutionwasderived.Theerrorestimatesareoptimal.

简介：Inthispaper,thenonlinearconjugatemapbasedontheconjugateRackwitz-FiesslerandHasofer-Lind(CHL-RF)methodisusedtoevaluatethereliabilityusingfirstorderreliabilitymethodoftheembeddednanocompositebeam,whichismadefrompolymerreinforcedwithcarbonnanotubs(CNTs).ThestructureissimulatedwithTimoshenkobeammodel.TheMori-Tanakamethodisappliedforobtainingtheeffectivepropertiesofnanocompositebeam.Thesurroundingelasticmediumisconsideredbyspringandshearconstants.UtilisingenergymethodandHamilton'sprincipal,thegoverningequationsareobtained.Usingananalyticalmethod,thebucklingperformancefunctionofstructureisobtained.Theinfluencesofthebasicrandomvariablesincludingthelengthtothicknessratioofbeam(L/h),springconstantandshearconstantoffoundationwithrespecttothevolumefractionofCNTsareinvestigatedonthereliabilityindexofthenanocompositebeamsubjectedtoaxialforceof20GPa.Theresultsindicatedthatthefailureprobabilitiesofthestudiedthenanocompositebeamarethesensitivetothelengthtothicknessofbeam(L/h)andspringconstantoffoundationvariables.

简介：Inthispaper,thenonlinearconjugatemapbasedontheconjugateRackwitz-FiesslerandHasofer-Lind(CHL-RF)methodisusedtoevaluatethereliabilityusingfirstorderreliabilitymethodoftheembeddednanocompositebeam,whichismadefrompolymerreinforcedwithcarbonnanotubs(CNTs).ThestructureissimulatedwithTimoshenkobeammodel.TheMori-Tanakamethodisappliedforobtainingtheeffectivepropertiesofnanocompositebeam.Thesurroundingelasticmediumisconsideredbyspringandshearconstants.UtilisingenergymethodandHamilton'sprincipal,thegoverningequationsareobtained.Usingananalyticalmethod,thebucklingperformancefunctionofstructureisobtained.Theinfluencesofthebasicrandomvariablesincludingthelengthtothicknessratioofbeam(L/h),springconstantandshearconstantoffoundationwithrespecttothevolumefractionofCNTsareinvestigatedonthereliabilityindexofthenanocompositebeamsubjectedtoaxialforceof20GPa.Theresultsindicatedthatthefailureprobabilitiesofthestudiedthenanocompositebeamarethesensitivetothelengthtothicknessofbeam(L/h)andspringconstantoffoundationvariables.

简介：ThisisoneoftheapplicationsofPart(Ⅰ),inwhichtheangularstiffness,andthecorrespondingstressdistributionsofU-shapedbellowswerediscussed.Thebellowswasdividedintoprotrudingsections,concavesectionsandringplatesforthecalculationthatthegeneralsolution(Ⅰ)withitsreducedformtoringplateswereusedrespectively,butthecontinuityofthesurfacestressesandthemeridianrotationsateachjointofthesectionswereentirelysatisfied.Thepresentresultswerecomparedwiththoseoftheslenderringshellsolutionproposedearlierbytheauthors,thestandardsoftheExpansionJointManufacturersAssociation(EJMA),theexperimentandthefiniteelementmethod.Itisshownthatthegoverningequationandthegeneralsolution(Ⅰ)areveryeffective.

简介：Thispaperfollowstheworkof[1,2].Therearesomeprogressindealingwithmoderatelysmallrotations(thesquaresofrotationanglesaretheorderofmagnitudeofstrains)ofmiddlesurfacenormalsofinsideandoutsideringshellsandcompressedangleofbellows.Calculationresultsagreewithexperimentswell.Tobellowdesign,themethodgiveninthispaperisofpracticalvalueandthediscussionoftheinfluenceofcompressedangleoncharacteristicrelationishelpful.

简介：针对SINS/GNSS组合导航在GNSS信号异常时出现的系统滤波精度和稳定性下降的问题,提出一种基于EKF的自适应分类容错滤波算法。该算法通过比较系统残差协方差矩阵的实际值与理论值来检测GNSS信号是否存在异常,然后对异常信号进行分类,并对不同类别的异常信号使用不同的加权矩阵进行修正,以减弱异常值对系统滤波精度的影响,同时在滤波过程中加入UD分解,使系统滤波性能更稳定。仿真结果表明：该算法能够有效降低GNSS输出异常信号对SINS/GNSS组合导航带来的不利影响并提高系统稳定性;在GNSS信号出现异常情况下,其导航精度相比EKF至少提高95.6%,相比REKF和AEKF分别至少提高44.5%和24.6%。

简介：通过采取快速插入、建立同步采集系统等措施,在中国航天空气动力技术研究院FD-07常规高超声速风洞建立了磷光热图技术,并成功地获得了平板三角翼模型表面热流分布.基于实验结果,初步分析了来流Reynolds数等参数对三角翼表面热流分布的影响.结果表明,三角翼外形中心线处转捩靠后,两侧转捩靠前,且随着来流Reynolds数的增加,转捩位置进一步前移.总的来说,磷光热图技术能够直观地显示流动转捩发生的位置以及转捩后湍流区的形状,为高超声速飞行器热防护设计提供了一种新的技术途径.