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  • 简介:Ageneralnonlinearconstitutivemodelisproposedformagnetostrictivematerials,basedontheimportantphysicalfactthatanonlinearpartoftheelasticstrainproducedbyapre-stressisrelatedtothemagneticdomainrotationormovementandisresponsibleforthechangeofthemaximummagnetostrictivestrainwiththepre-stress.Toavoidthecomplicityofdeterminingthetensorfunctiondescribingthenonlinearelasticstrainpart,thispaperproposesasimplifiedmodelbymeansoflinearizingthenonlinearfunction.Fortheconvenienceofengineeringapplications,theexpressionsofthe3-D(bulk),2-D(film)and1-D(rod)modelsare,respectively,givenforanisotropicmaterialandtheirapplicablerangesarealsodiscussed.BycomparisonwiththeexperimentaldataofaTerfenol-Drod,itisfoundthattheproposedmodelcanaccuratelypredictthemagnetostrictivestraincurvesinlow,moderateandhighmagneticfieldregionsforvariouscompressivepre-stresslevels.Thenumericalsimulationfurtherillustratesthat,foreithermagnetostrictiverodsorthinfilms,theproposedmodelcaneffectivelydescribetheeffectsofthepre-stressorresidualstressonthemagnetizationandmagnetostrictivestraincurves,whilenoneoftheknownmodelscancaptureallofthem.Therefore,theproposedmodelenjoyshigherprecisionandwiderapplicabilitythanthepreviousmodels,especiallyintheregionofthehighfield.

  • 标签: 非线性模型 磁致伸缩材料 磁致伸缩薄膜 弹性应力 磁场
  • 简介:Thedynamicresponseofthenon-linearelasticsimplysupportedbeamsubjectedtoaxialforcesandtransverseperiodicloadisstudied.Melnikovmethodisusedtoconsiderthedynamicbehav-iorofthesystemwhosepost-bucklingpathissteady.Theeffectofthehigherordertermsinthecon-trollingequationistakenintoaccount.Itisfoundthatthefifth-ordertermshaveagreatinfluenceonthedynamicbehaviorofthesystem.Theresultshowsthatthereexisteitherhomoclinicorbitsorhete-roclinicorbitsinthesystem.Inthispaper,thecriticalvaluesofthesystementeringchaoticstatesaregiven.Thediagramofanexampleisshown.

  • 标签: CHAOS HOMOCLINIC ORBIT HETEROCLINIC ORBIT MELNIKOV
  • 简介:Fromthegroupmovementofthebedloadwithinthebottomlayer,detailsofthenonlineardynamiccharacteristicsofbedloadmovementarediscussedinthispaper.Whetherthesedimentisinitiatedintomotioncorrespondstowhethertheconstanttermintheequationisequaltozero.Ifconstanttermiszeroandnodispersiveforceisconsidered,theequationrepresentsthetraditionalShieldsinitiationcurve,andifconstanttermiszerowithoutthedispersiveforcebeingconsidered,thenanewShieldscurvewhichismuchlowerthanthetraditionaloneisgot.Thefixedpointoftheequationcorrespondstotheequilibriumsedimenttransportofbedload.Inthemutationanalysis,wehavefoundthattheinflectionpointisthedemarcationpointofbreaking.Intheory,thebreakingpointcorrespondstothedividingboundaryline,acrosswhichthebedformchangesfromflatbedtosandrippleorsanddune.ComparedwiththeexperimentaldataofChatouHydraulicLabinFrance,theconclusionsareverified.

  • 标签: 非线性机制 非线性动态特性 输沙 运动负荷 启动曲线 常数项
  • 简介:Wededuceacompletewavepropagationequationthatincludesinhomogeneityofthedielectricconstantandpresentthispropagationequationincompactvectorform.Althoughsimilarequationsareknowninnarrowfieldssuchasradiowavepropagationintheionosphereandelectromagneticandacousticwavepropagationinstratifiedmedia,wedevelophereanovelapproachofusingsuchequationsinthemodelingoflaserbeampropagationinnonlinearmedia.Ourapproachsatisfiesthecorrespondenceprinciplesinceinthelimitofzero-lengthwavelengthitreducesfromphysicaltogeometricaloptics.

  • 标签: LIGHT PROPAGATION SELF-FOCUSING WAVEFRONT CORRECTION
  • 简介:Theconjugategradientmethodforunconstrainedoptimizationproblemsvarieswithascalar.Inthisnote,ageneralconditionconcerningthescalarisgiven,whichensurestheglobalconvergenceofthemethodinthecaseofstrongWolfelinesearches.ItisalsodiscussedhowtousetheresulttoobtaintheconvergenceofthefamousFletcher-Reeves,andPolak-Ribiere-Polyakconjugategradientmethods.Thattheconditioncannotberelaxedinsomesenseismentioned.

  • 标签: UNCONSTRAINED optimization CONJUGATE GRADIENT Line SEARCH
  • 简介:Startingfromnonlinearequationsonthef-planecontainingfrictionaldissipationundertheBoussinesqapproximation,anewkindofgeneralizedenergyisproposedastheLyapunovfunction,andaveragesaretakenasanyfunctionsof(x,z)insteadofthecommonly-usedmeansofbilinearfunctionsof(x,z),therebyresultinginanewcriterionofgeneralizednonlinearsymmetricstability.Itshowsthatnotonlymustthedissipativecoefficientbegreaterthanacertaincriticalvaluebuttheinitialdisturbanceamplitudemustbesynchronouslysmallerthananothermarginalvalueaswell.Itfollowsthatthelatterimposesacrucialconstraintontheformer,thusleadingtothefactthatwhentheamplitudeisbiggercomparedtoanothercriticalvalue,generalizednonlinearsubcriticalsymmetricalinstabilitymayoccur.Thenewcriterioncontributesgreatlytotheimprovementofthepreviousresultsofitskind.

  • 标签: 广义非线性亚临界对称稳定性 非线性方程组 LYAPUNOV函数 摩擦耗散 耗散系数 初始扰动振幅
  • 简介:Inanormalousdispersionofmonomodeopticalfiber,opticalsolitonsareevolvedfromopticalpulseswhenthedispersionisbalancedbythenonlinearity.Undistortedtransmissioncanberealizedbyusingopticalsolitons,whichcanoffermuchgreaterthetransmissioncapacityandextendtherepeaterspacingofthefibercommunicationsystem.Themechanismofthegenerationofopticalsolitonsisexpounded.Afewformsofnonlineartransmissionequationareobtainedbyusingaconcisemethod.Thegeneralcompleteexpressionofelementarysolitonsolutionofthenonlineartransmissionequationwithoutlossisgiven,andthedesignofthesolitontransmissionsystemisdiscussed.

  • 标签: NONLINEARITY DISPERSION SOLITON SOLITON INTERACTION
  • 简介:Someofthemathematicalpropertiesoftheinterfacebetweentwoincompressibleinviscidandimmisciblefluidswithdifferentdensitiesundertheinfluenceofaconstantgravityfieldgareinvestigated.ThepurposeofthispaperistoprovethatlinearlyunstablemodesforRayleigh-Taylorinstabilitiesgivebirthtononlinearinstabilitiesforthefullnonlinearsystem.Themainingredientisageneralinstabilitytheoreminananalyticframeworkwhichenablesustogofromlineartononlinearinstabilities.

  • 标签: 流体力学 不稳定性 非线性 光谱 解析规律
  • 简介:§1.IntroductionAssociatedwiththeeigenvalueproblem

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  • 简介:完美的改编描述一个生物系统的能力在被环境骚乱影响以后精确恢复它的生物函数到不安前水平。算术地,有完美的改编的一个生物系统能作为输入产量被建模产量的非线性的系统,通常决定生物函数,在担心的所有输入骚乱下面是asymptotically稳定的。在这份报纸,相当一般的输入产量数学模型被雇用并且生物功能(FBF)功能-产量Lyapunov功能-被探索调查它的完美的改编能力。足够的状况与FBF为系统被建立完成完美的改编。然后,一个足够、必要的条件被获得让线性系统拥有一个输出Lyapunov函数。而且,这被显示出受体功能活动在E的完美的改编模型存在。coli趋化性。与存在不同完美的改编,其大多数基于控制理论的立场,上的数学调查我们首先用非线性的系统分析的方法调查这个问题。

  • 标签: 系统科学 系统学 系统工程 理论
  • 简介:我们在某些合理假设下面考虑有弹性的薄盘子的颤动。我们由哈密尔顿原则为这个模型导出非线性的方程。在为起始的数据的hyperbolicity上的条件下面,我们建立本地时间well-posedness为起始并且由Picard重复的边界值问题为解决方案策划,并且获得估计。

  • 标签: 弹性薄板 板振动 非线性分析 HAMILTON原理 非线性方程组 初边值问题
  • 简介:交换非线性的系统的一个类的稳定在纸被调查。担心的系统具有(概括)交换了Byrnes-Isidori正规形式,它都交换了模型在(概括)Byrnes-Isidori正规形式。首先,交换系统的稳定性结果被获得。然后,解决交换非线性的控制系统的稳定问题被用来。另外,必要;足够的条件为是等价于的反馈的一个交换仿射的非线性的系统被获得(概括)交换Byrnes-Isidori正规系统被介绍。最后,作为一个应用程序,交换lorenz系统的稳定性被调查。

  • 标签: 非线性转换系统 稳定性 规范模式 LYAPUNOV函数