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49 个结果
  • 简介:Inthispaper,wederivetheanalyticalsolutionsinathree-dimensionalanisotropicmagnetoelectroelasticbimaterialspacesubjecttouniformextendeddislocationsandtractionswithinahorizontalcirculararea.ByvirtueoftheStrohformalismandFouriertransformation,thefinalexpressionofsolutionsinthephysicaldomaincontainsonlylineintegralsover[0,2π]ratherthaninfiniteintegrals.Asthereducedcases,thehalf-spaceandhomogeneousfull-spacesolutionscanbedirectlyderivedfromthepresentsolutions.Also,intermsofmaterialdomains,thepresentsolutionscanbereducedtothepiezoelectric,piezomagnetic,purelyelasticmaterialswithdifferentsymmetriesofmaterialproperty.Tocarryoutnumericalcalculations,Gaussquadratureisadopted.Inthenumericalexamples,theeffectofdifferentloadinglocationsontheresponseattheinterfaceisanalyzed.Itisshownthat,whenthemagnetictractionorelectricdislocationisapplied,thephysicalquantitiesontheinterfacemaynotdecreasemonotonicallyastheloadingareamovesawayfromtheinterface.Thedistributionsofdifferentin-planephysicalquantitiesontheupperandlowerinterfacesundervariousextendedhorizontalloadingsarecomparedandthedifferencesarediscussed.Theworkpresentedinthispapercanserveasbenchmarksforfuturenumericalstudiesinrelatedresearchfields.

  • 标签: 扩展位错 各向异性 圆形区域 牵引 均匀 磁电
  • 简介:Inthispaper,aresearchontheproblemofmultiplesolutionsofthethree-coefficientlow-spectrummodelforthequasi-geostrophicoceancurrentequationwithforcinganddissipationtermsiscarriedout.Thestateoftheoceancurrentunderwindconditionssuchasthoseoftyphoonisdiscussedcarefullyandtherela-tionsbetweenthemultiplesolutionsandthecoefficientsRandεareanalyzed.Itisseenthatinanapproxi-matetriangularregionwiththeRossby-coefficientRlessthan0.5,andthefriction-coefficientεlessthan0.22,thereexistthreeequifibriumsolutions,amongwhichtwoarestableandoneisunstable.Fortheformer,thecoefficientAorBintheexpansionisratherlarge,whileforthelatter,AorBisrelativelysmall.TheyrespectivelyimplyhowmuchtheoceanenergyisfedbackfromthewindstressandthesolutionwithalargeAismuchmorestablethanthatwithalargerB.

  • 标签: OCEAN EQUATION low SPECTRAL model multiple
  • 简介:ThePainlev'eintegrabilityandexactsolutionstoacouplednonlinearSchr¨odinger(CNLS)equationappliedinatmosphericdynamicsarediscussed.SomeparametricrestrictionsoftheCNLSequationaregiventopassthePainlev'etest.TwentyperiodiccnoidalwavesolutionsareobtainedbyapplyingtherationalexpansionsoffundamentalJacobiellipticfunctions.TheexactsolutionstotheCNLSequationareusedtoexplainthegenerationandpropagationofatmosphericgravitywaves.

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  • 简介:Twodimensionalequationsofsteadymotionforthirdorderfluidsareexpressedinaspecialcoordinatesystemgeneratedbythepotentialflowcorrespondingtoaninviscidfluid.Fortheinviscidflowaroundanarbitraryobject,thestreamlinesarethephicoordinatesandvelocitypotentiallinesarepsi-coordinateswhichformanorthogonalcurvilinearsetofcoordinates.Theoutcome,boundarylayerequations,isthenshowntobeindependentofthebodyshapeimmersedintotheflow.Asafirstapproximation,assumptionthatsecondgradetermsarenegligiblecomparedtoviscousandthirdgradeterms.Secondgradetermsspoilscalingtransformationwhichisonlytransformationleadingtosimilaritysolutionsforthirdgradefluid.ByusingLiegroupmethods,infinitesimalgeneratorsofboundarylayerequationsarecalculated.Theequationsaretransformedintoanordinarydifferentialsystem.NumericalsolutionsofoutcomingnonlineardifferentialequationsarefoundbyusingcombinationofaRunge-Kuttaalgorithmandshootingtechnique.

  • 标签: 李群 边界层方程 第三级流体 非牛顿流体 流体力学
  • 简介:Optimalcontrolsystemofstatespaceisaconservativesystem,whoseapproximatemethodshouldbesymplecticconservation.Basedonthepreciseintegrationmethod,analgorithmofsymplecticconservativeperturbationispresented.Itgivesauniformwaytosolvethelinearquadraticcontrol(LQcontrol)problemsforlineartime-varyingsystemsaccuratelyandefficiently,whosekeypointsaresolutionsofdifferentialRiccatiequation(DRE)withvariablecoefficientsandthestatefeedbackequation.Themethodissymplecticconservativeandhasagoodnumericalstabilityandhighprecision.Numericalexamplesdemonstratetheeffectivenessoftheproposedmethod.

  • 标签: 线性时变系统 线性二次控制 辛守衡摄动法 数值解
  • 简介:Aclassofperiodicinitialvalueproblemsfortwo-dimensionalNewton-Boussinesqequationsareinvestigatedinthispaper.TheNewton-Boussinesqequationsareturnedintotheequivalentintegralequations.Withiterationmethods,thelocalexistenceofthesolutionsisobtained.Usingthemethodofaprioriestimates,theglobalexistenceofthesolutionisproved.

  • 标签: BOUSSINESQ方程 初值问题 牛顿 二维 周期 局部存在性
  • 简介:TheSchmidtmethodisadoptedtoinvestigatethefractureproblemofmultipleparallelsymmetricandpermeablefinitelengthmode-IIIcracksinafunctionallygradedpiezoelectric/piezomagneticmaterialplane.Thisproblemisformulatedintodualintegralequations,inwhichtheunknownvariablesarethedisplacementjumpsacrossthecracksurfaces.Inordertoobtainthedualintegralequations,thedisplacementjumpsacrossthecracksurfacesaredirectlyexpandedasaseriesofJacobipolynomials.Theresultsshowthatthestress,theelectricdisplacement,andthemagneticfluxintensityfactorsofcracksdependonthecracklength,thefunctionallygradedparameter,andthedistanceamongthemultipleparallelcracks.Thecrackshieldingefectisalsoobviouslypresentedinafunctionallygradedpiezoelectric/piezomagneticmaterialplanewithmultipleparallelsymmetricmode-IIIcracks.

  • 标签: 压磁材料 功能梯度 对称模式 III 裂缝 平行
  • 简介:Thispaperinvestigatesthestaticbehaviorofafunctionallygradedcircularplatemadeofmagneto-electro-elastic(MEE)materialsundertensionandbending.Theanalysisisdirectlybasedonthethree-dimensionalgoverningequationsformagnetoelectro-elasticity,withtheboundaryconditionsontheupperandlowersurfacessatisfiedexactlyandthoseonthecylindricalsurfacesatisfiedapproximately(intheSaintVenantsense).Theanalyticalsolutions,derivedwithadirectdisplacementmethod,arevalidforanyfunctionallygradedmaterial(FGM)withitspropertiesvaryingindependentlyinacontinuousmanneralongthethicknessdirection.Forhomogeneousmaterials,thesesolutionsaredegeneratedtotheonesavailableintheliterature.Interestingrelationsarealsofoundbetweenthesolutionsforafunctionallygradedmagneto-electro-elastic(FGMEE)circularplateandthoseforanFGMEErectangularbeam,andeventhoseforafunctionallygradedelasticbeamwhenonlytheelasticdisplacementsareconsidered.Thebeamsolutionsarealsoderivedusingadirectdisplacementmethod.Numericalexamplesarepresentedtoverifythepresentanalyticalsolutions,showtheeffectsofmaterialheterogeneityandmulti-fieldcoupling,andindicatethecorrespondencebetweentheplatesolutionsandbeamsolutions.

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  • 简介:Ironcatalystnanoparticleswerepreparedonsiliconwafersbyspin-coatingcolloidalsolutionscontainingironnitrate,polyethyleneglycol(PEG)andabsoluteethanol.Theeffectsofvariousspin-coatingconditionswereinvestigated.Thefindingsshowedthatthesizeoftheironparticleswasgovernedbythecompositionofthecolloidalsolutionusedandthatahighangularspeedwasresponsiblefortheformationofathincolloidalfilm.Theeffectofangularaccelerationonthesizeanddistributionoftheironparticleswerefoundtobeinsignificant.Itwasobservedthatalongerspin-coatingdurationprovokedtheagglomerationofironparticles,leadingtotheformationoflargeparticles.Wealsoshowedthatsingle-walledcarbonnanotubescouldbegrownfromthesmallestironcatalystnanoparticlesafterthechemicalvapordepositionofmethane.

  • 标签: 单壁碳纳米管 铁纳米粒子 胶体溶液 无水乙醇 PEG 旋涂