简介：OfconcernisaviscoelasticbeammodelledusingtheTimoshenkotheory.Itiswell-knownthatthesystemisexponentiallystableifthekernelinthememorytermissub-exponential.Thatis,iftheproductofthekernelwithanexponentialfunctionisasummablefunction.Inthisarticleweaddressthequestions:Whatifthekernelistestedagainstadifferentfunction(sayGamma)otherthantheexponentialfunction?Wouldtherestillbestability?Intheaffirmative,whatkindofdecayrateweget?Itisprovedthatforanon-decreasingfunction'Gamma'whose'logarithmicderivative'isdecreasingtozerowehaveadecayoforderGammatosomepowerandinthecaseitdecreasestoadifferentvaluethanzerothenthedecayisexponential.

简介：mass-spring-damper-type的古典理论平常的扁平的空间3上的动态系统可以被reformulating概括到高度维的Riemannianmanifolds通过微分几何学的基本内在的物理原则。因为他们从当模特儿复杂物理结构自然地产生并且因为如此的动态系统为象信息的安全传播那样的几个现代应用程序组成基础，非线性的动态系统在科学文学被学习了。非线性的动态系统的流动可以在建筑群随着时间的过去演变，非重复(尽管确定)模式。现在的纸的焦点在提出描述在以一种没有坐标的方式歧管的Riemannian上滑动的一个点明智的粒子的动力学的一般方程上。纸显示出方程怎么在对科学文学的兴趣的某manifolds的情况中列举，例如歧管的Stiefel并且对称的积极明确的矩阵歧管。

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简介：ＦｌｕｃｔｕａｔｉｏｎｏｆＥｘｃｉｔａｔｉｏｎＦｕｎｃｔｉｏｎｓｏｆＤａｍｐｅｄＰｒｏｄｕｃｔｓｏｆＩｄｅｎｔｉｆｉｅｄＩｓｏｔｏｐｅｓ￥ＷａｎｇＱｉ；ＬｕＪｕｎ；ＸｕＨｕｓｈａｎ；ＬｉＳｏｎｇｌｉｎ；ＺｈｕＹｏｎｇｔａｉ；ＹｉｎＸ...

简介：为有抑制Δ~2x_n+p_nΔx_n+F的非线性的延期差别方程的一些新摆动标准(n，x_(n-τ)，Δx_(n-σ))=0，n=0,1,2，...，(*)被给。我们的结果部分解决摆姿势在的开的问题[数学。Bohemica，125(2000)，421-430]。另外，我们将为(*)的特殊情况建立一些新摆动标准，它在文学改进一些知道thewell的结果。

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简介：Thispaperinvestigatesaclassofevenorderfunctionaldifferentialequationswithdampedterm,andderivestwonewoscillatorycriteriaofsolution.

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简介：Anewresponse-spectrummodesuperpositionmethod,entirelyinrealvalueform,isdevelopedtoanalyzethemaximumstructuralresponseunderearthquakegroundmotionforgenerallydampedlinearsystemswithrepeatedeigenvaluesanddefectiveeigenvectors.Thisalgorithmhasclearphysicalconceptsandissimilartothecomplexcompletequadraticcombination(CCQC)methodpreviouslyestablished.Sinceitcanconsidertheeffectofrepeatedeigenvalues,itiscalledtheCCQC-Rmethod,inwhichthecorrelationcoefficientsofhigh-ordermodalresponsesareenclosedinadditiontothecorrelationcoefficientsinthenormalCCQCmethod.Asaresult,theformulasforcalculatingthecorrelationcoefficientsofhigh-ordermodalresponsesarededucedinthisstudy,includingdisplacement,velocityandvelocity-displacementcorrelationcoefficients.Furthermore,therelationshipbetweenhigh-orderdisplacementandvelocitycovarianceisderivedtomaketheCCQC-Ralgorithmonlyrelevanttothehigh-orderdisplacementresponsespectrum.Finally,apracticalstep-by-stepintegrationprocedureforcalculatinghigh-orderdisplacementresponsespectrumisobtainedbychangingtheearthquakegroundmotioninput,whichisevaluatedbycomparingittothetheorysolutionunderthesine-waveinput.Themethodderivedhereissuitableforgenerallylinearsystemswithclassicalornon-classicaldamping.

简介：完整的波形倒置(FWI)直接最小化在合成、观察的数据之间的错误。为表面获得几何学，从深反射镜产生的思考是敏感的压垂组织，因此更新宏速度模型在是合理的一从上到下举止。为水平地分层的结构统治的模型，偏移量/时间weighting和经常的更改深度控制(CUDC)的联合为剥去层的FWI是足够的。CUDC要求光线跟踪在经常的深度决定思考traveltimes。作为模型复杂性增加，多路径效果将不得不被考虑。我们开发了利用抑制地震思考数据的一个新剥去层的FWI方法，它不需要CUDC并且光线跟踪。数字例子证明有效更改深度(EUD)能被甚至在复杂区域抑制常数控制，倒置结果比常规方法更精确。

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简介：Fundamentalprinciplesfromstructuraldynamics,randomtheoryandperturbationmethodsareadoptedtodevelopanewresponsespectrumcombinationrulefortheseismicanalysisofnon-classicallydampedsystems,suchasstructure-dampersystems.Theapproach,whichisnamedtheperturbationspectrummethod,canprovideamoreaccurateevaluationofanon-classicallydampedsystem'smeanpeakresponseintermsofthegroundresponsespectrum.Toaccountfortheeffectofnon-classicaldamping,allelementsareincludedintheproposedmethodforseismicanalysisofstructure,whichisusuallyap-proximatedbyignoringtheoff-diagonalelementsofthemodaldampingmatrix.Moreover,ashasbeenadoptedinthetraditionalCompleteQuadraticCombination(CQC)method,thewhitenoisemodelisalsousedtosimplifytheexpressionsofperturbationcorrelationcoefficients.Finally,numericalworkisperformedtoexaminetheaccuracyoftheproposedmethodbycomparingtheapproximateresultswithexactonesandtodemonstratetheimportanceoftheneglectedoff-diagonalelementsofthemodaldampingmatrix.Intheexaminedcases,theproposedmethodshowsgoodagreementwithdirecttime-historyintegration.Also,theperturbationspectrummethodleadstoamoreefficientandeconomicalcalculationbyavoidingtheintegralandcomplexoperation.

简介：Amethodtocalculatethestationaryrandomresponseofanon-classicallydampedstructureisproposedthatfeaturesclearly-definedphysicalmeaningandsimpleexpression.Themethodisdevelopedinthetrequencydomain.Theexpressionoftheproposedmethodconsistsofthreeterms,i.e.,modalvelocityresponse,modaldisplacementresponse,andcoupled(betweenmodalvelocityandmodaldisplacementresponse).Numericalresultsfromtheparametricstudyandthreeexamplestructuresrevealthatthemodalvelocityresponsetermandthecoupledtermareimportanttostructuralresponseestimatesonlyforadynamicsystemwithatunedmassdamper.Intypicalcases,themodaldisplacementtermcanprovideresponseestimateswithsatisfactoryaccuracybyitself,sothatthemodalvelocitytermandcoupledtermmaybeignoredwithoutlossofaccuracy.Thisisusedtosimplifvtheresponsecomputationofnon-classicallydampedstructures.Forthewhitenoiseexcitation,threemodalcorrelationcoefficientsmclosedformarederived.Toconsiderthemodalvelocityresponsetermandthecoupledterm,asimplifiedapproximationbasedonwhitenoiseexcitationisdevelopedforthecasewhenthemodalvelocityresponseisimportanttothestructuralresponses.Numericalresultsshowthattheapproximateexpressionbasedonwhitenoiseexcitationcanprovidestructuralresponseswithsatisfactoryaccuracy.

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简介：Thispaperproceedsfromthegeneralcaseoftheunsymmetriclinearizedmulti-degreesoffree-dom(MDOF)systems.Byadoptingthegeneralcomplexmodaltheoryofthestatespace,theresponseanalysisforasys-temsubjectedtorandomexcitationofthesamesourceiscarriedoutusingasakindofdirectspectrumanalysismethodinfrequencydomain.Withtheinputofpowerspectraldensityfunctiongiven,theexplicitexpressionofthepowerspectraldensityfunctionmatrixoftheoutputresponsecanbeobtained.BytakingFourierinversetransform,theintegratedexpres-sionsofthecorrelationfunctionmatrixandofthespectrummomentmatrixareobtained.Comparingwiththetimedomainmethod,thismethodenjoysthemeritofvisualizationandavoidstheprocedureoftransformationfromtheobtainedre-sponsecorrelationfunctiontobesolvedfortheoutputspectrumutilizingFouriertransform.Thispaperhasextendedtheapplicationrangeofthetraditionalfrequencydomainanalysismethod.Themeansquarevaluesandvarietyofstatisticalval-uescanbeobtainedconveniently.Thismethodandthetimedomainmethodaredifferentinapproachbutequallysatisfac-toryintheirresults.

简介：NonlinearSchrodingerequation(NSE)arisesinmanyphysicalproblems.Itisaveryimportantequation.Alotofworksstudiedthewellposed,theexistenceofsolutionofNSEetc.Andtherearemanyworksstudiedthenumericalmethodsforit.Recently,sincethedevelopmentofinfinitedimensionaldynamicsystemthedynamicalbehaviorofNSEhasbeeninvestigated.Thepaper[1]studiedthelongtimewellposedness,theexistenceofuniversalattractorandtheestimateofLyapunovexponentforNSEwithweaklydamped.Atthesametimeitwasneedtostudythelargetimenewcomputationalmethodsandtodiscussitsconvergenceerrorestimate,theexistenceofapproximateattractorsetc.InthispapewestudytheNSEwithweaklydamped(1.1).Weassume,where0<λ<2isaconstant.Ifwewishtoconstructthehigheraccuracycomputationalscheme,itwillbedifficultthatstaighfromtheequation(1.1).Thereforewestartwith(1.4)andusefullydiscreteFourierspectralmethodwithtimedifferencetodisscus

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简介：与联合了在担心下面受到添加剂和趋于增加的噪音的弱抑制的周期性地驾驶的双稳态的振荡器，这份报纸的目的是检查到到什么程度，反响的点由Gaussian分发预言假设能接近模仿的。调查基于动态吝啬地的近似和直接模拟证明预言的反响的点和模仿的点为纯添加剂噪音的盒子是基本上重合的，但是为包括趋于增加的噪音的盒子，状况变得有点复杂。当随机的回声(SR)被改变添加剂噪音紧张观察时，明确地说，预言的反响的点比模仿的那个低；不过，当SR被改变趋于增加的噪音紧张观察时，预言的反响的点比模仿的那个高。我们的观察暗示Gaussian分发假设不能确切描述实际状况，但是它对在预言联合弱抑制的双稳态的振荡器的低频率的随机的回声的某程度有用。

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