简介:Anewmethodforestimationtheboundsofeigenvaluesispresented.InordertoshowthatthemethodproposeisaseffectiveasQiu’s,anundampingspring-masssystemwith5nodesand5degreesoffreedomisgiven.Toillustratethatthepresentmethodcanbeappliedtostructureswhichcannotbetreatedbynon-negativedecompsition,aplandframewith202nodesand357beamelementsisgiven.TheresultsshowthatthepresentmethodiseffectiveforestimatingtheboundsofeigenvaluesandismorecommonthanQiu’s.
简介:Anewstochasticoptimalcontrolstrategyforrandomlyexcitedquasi-integrableHamiltoniansystemsusingmagneto-theological(MR)dampersisproposed.ThedynamicbehaviorofanMRdamperischaracterizedbytheBouc-Wenhystereticmodel.ThecontrolforceproducedbytheMRdamperisseparatedintoapassivepartincorporatedintheuncontrolledsystemandasemi-activeparttobedetermined.ThesystemcombiningtheBouc-Wenhystereticforceisconvertedintoanequivalentnon-hystereticnonlinearstochasticcontrolsystem.ThenItostochasticdifferentialequationsarederivedfromtheequivalentsystembyusingthestochasticaveragingmethod.Adynamicalprogrammingequationforthecontrolleddiffusionprocessesisestablishedbasedonthestochasticdynamicalprogrammingprinciple.Thenon-clippingnonlinearoptimalcontrollawisobtainedforacertainperformanceindexbyminimizingthedynamicalprogrammingequation.Finally,anexampleisgiventoillustratetheapplicationandeffectivenessoftheproposedcontrolstrategy.
简介:Anapproachbasedoncontinuumdamagemechanicstofatiguelifepredictionforstructuresisproposed.Anewfatiguedamageevolutionequationisdeveloped,inwhichtheparametersareobtainedinasimplewaywithreferencetotheexperimentalresultsoffatiguetestsonstandardspecimens.WiththeutilizationofAPDLlanguageontheANSYSplatform,afiniteelementimplementationispresentedtoperformcouplingoperationondamageevolutionofmaterialandstressredistribution.ThefatiguelivesofsomenotchedspecimensandaPitch-change-linkarepredictedbyusingtheaboveapproach.Thecalculatedresultsarevalidatedwithexperimentaldata.
简介:Inthepreviouspapers,ahighperformancesparsestaticsolverwithtwo-levelunrollingbasedonacell-sparsestorageschemewasreported.Althoughthesolverreachesquiteahighefficiencyforabigpercentageoffiniteelementanalysisbenchmarktests,theMFLOPS(millionfloatingoperationspersecond)ofLDLTfactorizationofbenchmarktestsvaryonaDellPentiumⅣ850MHzmachinefrom100to456dependingontheaveragesizeofthesuper-equations,i.e.,ontheaveragedepthofunrolling.Inthispaper,anewsparsestaticsolverwithtwo-levelunrollingthatemploystheconceptofmaster-equationsandsearchesforanappropriatedepthsofunrollingisproposed.ThenewsolverprovideshigherMFLOPSforLDLTfactorizationofbenchmarktests,andthereforespeedsupthesolutionprocess.