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简介：Inthispaperanewapproachisdevelopedtovaluelifeinsurancecontractsbymeansofthemethodofbackwardstochasticdifferentialequation.Suchavaluationmayrelaxcertainmarketlimitations.Followingthisapproach,thevaluesofsingledecrementpoliciesarestudiedandThiele's-typePDEsforgenerallifeinsurancecontractsarederived.

简介：Considerthemotionofimmersedhypersurfacesdrivenbysurfacediffusionflowandgiveanlowerboundonthelifespanofasmoothimmersedsolution,whichdependsonlyonhowmuchthecurvatureoftheinitialsurfaceisconcentratedinspace.

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简介：Thermalfatigue(TF)isoneofthemostimportantfactorsthatinfluenceturbine'slife.Thispaperestablishesa3Dsolid-fluidcouplingmodelforasteadytemperatureanalysisofahigh-pressureturbinenozzleatdifferentturbineinletgastotaltemperatures(TIGTTs).Thetemperatureanalysissuppliesthetemperatureloadforsubsequent3Dfiniteelementanalysistoobtainthestrainvalues.Followingthis,thepredictionoftheTFlifeismadeonthebasisofequivalentstrainrange.TheresultsshowthatthestrainincreaseswithTIGTT,andthepredictedTFlifedecreasescorrespondingly.ThislifepredictionwasconfirmedbyoneTFtest.

简介：Acousticfatiguelifeevaluationisessentialforthermalprotectionstructuresduetotheseverethermo-acousticloadinservice.AstudyontemperaturedependenceofacousticfatiguelifeforaC/SiCpanelispresentedinthispaper.EffectsoftemperatureonboththestructuralresponsesandtheS–Ncurvesareinvestigated.TheDirlikmethodisadoptedtopredictthefatiguelifeofaC/SiCpanelatthreedifferenttemperaturesrespectively.Significantdifferencesareobservedfromtheresultsofnumericalsimulationsbetweenthefatiguelivesofthepanelinthethreecases.Thetemperature-dependenceofacousticfatiguelifeofaC/SiCpanelisverified,andfatiguetestofthematerialneedstobemoreattentivelyperformed.

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简介：Thefatiguebehaviorofahighstrengthsteel300Minthegigacycleregimewasinvestigated.Fullyreversedtension-compressionfatiguetestsatambienttemperaturewereperformedusinganultrasonicfatiguesystemoperatingat20kHz.Thestaircasetestmethodwasemployedtoobtainaccuratevaluesofthemeanfatiguestrengthcorrespondingtofixednumbersofcyclesupto10~9.Theseresultswerecomparedtothecurvewhichisestimatedbythedatatestedinthemid-longliferegimeonconventionalservohydraulictestmachineat20Hz.Resultsindicatethatthefatiguestrengthdeterminedfromultrasonicfatiguetestingislightlyhigherthanconventionaltestingintherangeof10~6-10~7cycles.Itisobviousthatnucleationsoffracturestendtooccurbelowthesurface,iffractureshappenaftermorethan10~7cycles.AllthefracturedspecimensfailsfrominternalSiO_2inclusionsorsmallercarbidesandcarbideclusters.

简介：ThispaperdealswiththeCauchyproblemforadoublysingularparabolicequationwithaweightedsource■whereN≥1,1max{0,3-p-p/N}satisfying21,andα>N(3-p-m)-p.Wegivethesecondarycriticalexponentonthedecayasymptoticbehaviorofaninitialvalueatinfinityfortheexistenceandnon-existenceofglobalsolutionsoftheCauchyproblem.Moreover,thelifespanofsolutionsisalsostudied.更多还原

简介：Anapproachbasedoncontinuumdamagemechanicstofatiguelifepredictionforstructuresisproposed.Anewfatiguedamageevolutionequationisdeveloped,inwhichtheparametersareobtainedinasimplewaywithreferencetotheexperimentalresultsoffatiguetestsonstandardspecimens.WiththeutilizationofAPDLlanguageontheANSYSplatform,afiniteelementimplementationispresentedtoperformcouplingoperationondamageevolutionofmaterialandstressredistribution.ThefatiguelivesofsomenotchedspecimensandaPitch-change-linkarepredictedbyusingtheaboveapproach.Thecalculatedresultsarevalidatedwithexperimentaldata.

简介：Theauthorconsidersthelife-spanofclassicalsolutionstoCauchyproblemforgeneralfirstorderquasilinearstrictlyhyperbolicsystemsintwoindependentvariableswith"slow"decayinitialdata.Byconstructinganexample,firstitisillustratedthattheclassicalsolutiontothiskindofCauchyproblemmayblowupinafinitetime,evenifthesystemisweaklylinearlydegenerate.Thensomelowerboundsofthelife-spanofclassicalsolutionsaregiveninthecasethatthesystemisweaklylinearlydegenerate.Theseestimatesimplythat,whenthesystemisweaklylinearlydegenerate,theclassicalsolutionexistsalmostgloballyintime.Finally,itisprovedthatTheorems1.1-1.3in[2]arestillvalidforthiskindofinitialdata.

简介：Hydrousrutheniumoxide（h-RuO2）nanoparticlesanditscompositewithmultiwalledcarbonnanotubes（h-RuO2/MWCNT）weresynthesizedbyasimplehydrothermalmethodandprovedtohavepotentialapplicationashybridsupercapacitormaterial.Theh-RuO2andh-RuO2/MWCNTwerecharacterizedfortheirphysico-chemicalpropertiesbyPXRD,BETsurfacearea,Raman,SEM-EDSandTEMtechniques.Theelectrochemicalperformanceofthematerialswereinvestigated,specificcapacitance（Cs）ofh-RuO2andhRuO2/MWCNTestimatedbytheircyclicvoltammetricstudieswerefoundtobe604and1585F/grespectivelyatascanrateof2mV/sinthepotentialrange0–1.2V.Further,thisvaluewasfoundtobenearlythreetimeshigherthanthatofpureh-RuO2.Anasymmetricsupercapacitor（AS）devicewasfabricatedbyemployingh-RuO2/MWCNTasthepositiveelectrodeandactivatedcarbonasthenegativeelectrode.ThedeviceexhibitedCsof61.8F/gatascanrateof2mV/s.Further,thedeviceshowedexcellentlongtermstabilityfor20,000cycleswith88%capacitanceretentionatahighcurrentdensityof25A/g.

简介：Toconsidertheanisotropicdamageinfatigue,animprovedboom-panelmodelispresentedtosimulatearepresentativevolumeelement(RVE)intheframeworkofcontinuumdamagemechanics.TheanisotropicdamagestateoftheRVEisdescribedbythecontinuityextentsofboomsandpanels,whosedamageevolutionsareassumedtobeisotropic.Thenumericalimplementationisproposedonthebasisofdamagemechanicsandthefiniteelementmethod.Finally,theapproachisappliedtothefatiguelifepredictionof2A12-T4aluminiumalloyspecimenundercyclicloadingoftension-torsion.Theresultsindicateagoodagreementwiththeexperimentaldata.