简介:Tworocksampleswithdifferentstructuresandmaterialsweredeformedunderabiaxialloadingsystem,andmulti-pointstrainmeasurementswereperformedforeachsample.ThedistributionofstrainanomaliesduringthedeformationandtheinstabilityprocesswereanalyzedbyusingCvvalueputforwardbyWANGXiao-qingandCHENXue-zhong,etal,aparametertodescribetheheterogeneousdistributionofearthquakeprecursors,soastoexaminethemethodofCvvalueandtoexploreitsphysicalmeaningexperimentally.TheresultshowsthatthechangeofCvvalueiscorrelatedtothechangeofdeformationcharacteristicsandisaneffectiveparametertodescribetheheterogeneityofprecursordistribution.Cvvalueincreasesfirstlyandthendecreasesbeforetheinstability,andtheinstabilityoccurswhenCvvaluedecreasestothelevelbeforeincreasing.ThisindicatesthatCvvaluemaybeausefulparameterforearthquakeprediction.
简介:在这篇论文,一个新奇参量的基于模型的分解方法为变化时间的结构监视的结构的健康被建议。为这个目的,先进功能系列的时间依赖者汽车回归的动人的一般水准(FS-TARMA)技术被用来估计在参量的信号分解计划使用的参数和革新变化。另外,一个唯一的特征抽取和减小方法基于分解信号,已知的同样潜伏的部件(LC),被建议。为了在实验室评估建议方法,数字模拟和试验性的研究的效率,在变化时间的结构上被进行,在损坏的各种各样的类型被介绍的地方。模糊专家系统(FES)被用作一个分类工具当时,证明建议方法成功地识别不同结构的条件与另外的方法相比基于非减少、平常的特征抽取。
简介:Evolutionarycomputationbasedontheideaofbiologicevolutionisonetypeofglobaloptimizationalgorithmthatusesself-adaptation,self-organizationandrandomsearchingtosolveoptimizationproblems.Theevolutionary-simplexalgorithmisintroducedinthispaper.Itcontainsfloatingencodingwhichcombinestheevolutionarycomputationandthesimplexalgorithmtoovcrcomctheproblemsencounteredinthegeneticalgorithmandevolutionarystrategymethods.Numericalcxpcrimcntsarcperformedusingseventypicalfunctionstoverifythealgorithm.Aninverseanalysismethodtoidentifystructuralphysicalparametersbasedonincompletedynamicresponsesobtainedfromtheanalysisinthetimedomainisprcscntcdbyusingtheevolutionary-simplexalgorithm.Themodalevolutionary-simplexalgorithmconvertedfromthetimedomaintothemodaldomainisproposedtoimprovetheinverseefficiency.Numericalcalculationsfora50-DOFsystemshowthatwhcncomparedwithothermethods,theevolutionary-simplexalgorithmoffersadvantagesofhighprecision,cfficientsearchingability,strongabilitytoresistnoise,independenceofinitialvalue,andgoodadaptationtoincompleteinformationconditions.
简介:Thispaperpresentsacopulatechniquetodeveloptime-variantseismicfragilitycurvesforcorrodedbridgesatthesystemlevelandconsiderstherealistictime-varyingdependenceamongcomponentseismicdemands.Basedonmaterialdeteriorationmechanismsandincrementaldynamicanalysis,thetime-evolvingseismicdemandsofcomponentswereobtainedintheformofmarginalprobabilitydistributions.Thetime-varyingdependencesamongbridgecomponentswerethencapturedwiththebestfittingcopulafunction,whichwasselectedfromthecommonlyusedcopulaclassesbytheempiricaldistributionbasedanalysismethod.Thesystemtime-variantfragilitycurvesatdifferentdamagestatesweredevelopedandtheeffectsoftime-varyingdependencesamongcomponentsonthebridgesystemfragilitywereinvestigated.Theresultsindicatethetime-varyingdependenceamongcomponentssignificantlyaffectsthetime-variantfragilityofthebridgesystem.Thecopulatechniquecapturesthenonlineardependenceamongcomponentseismicdemandsaccuratelyandeasilybyseparatingthemarginaldistributionsandthedependenceamongthem.
简介:Incorporatingrateandstatefrictionlaws,stabilityoflinearlystable(i.e.,withstiffnessgreaterthanthecriticalvalue)spring-slidersystemssubjectedtotriggeringperturbationswasanalyzedundervariablenormalstresscondition,andcomparisonwasmadebetweenourresultsandthatoffixednormalstresscasesrevealedinpreviousstudies.Forsystemsassociatedwiththesliplaw,thecriticalmagnitudeofratestepsfortriggeringunstableslipsarefoundtohaveasimilarpatterntothefixednormalstresscase,andthecriticalvelocitystepsscalewitha/(b-a)whenk=kcrforbothcases.Therate-stepboundariesforthevariablenormalstresscasesarerevealedtobelowerthanthefixednormalstresscaseby7%–16%forarelativelylargea=0.56with(b-a)/arangingfrom0.25to1,indicatingeasiertriggeringunderthevariablenormalstressconditionwithratesteps.Thedifferencebetweenfixedandvariablenormalstresscasesdecreaseswhentheavalueissmaller.Inthesamesliplaw-typesystems,criticaldisplacementstotriggerinstabilityarerevealedtobelittleaffectedbythevariablenormalstresscondition.WhenkCkcr(V*),aspring-slidersystemwiththeslownesslawismuchmorestablethanwiththesliplaw,suggestingthattheslownesslawfitsexperimentaldatabetterwhenasinglestatevariableisadopted.Instick-slipmotions,thevariablenormalstresscasehaslargerstressdropsthantheconstantnormalstresscase.Thevariablenormalstresshaslittleeffectontherangeofslipvelocityinsystemsassociatedwiththeslownesslaw,whereassystemsassociatedwiththesliplawhaveaslowestslipvelocityimmenselysmallerthanthefixednormalstresscase,by*10ordersofmagnitude.
简介:这个地点和结构的参数无常的动态效果的考虑被标准在大多数国家为核电厂(NPP)要求。抗地震的标准提供二个基本方法分析参数无常。手工地直接处理计算地板反应系列(皇家学会会员)确定的途径珍视是第一个方法。第二个方法是执行概率统计的FRS的分析根据蒙特卡罗方法结果。二个方法能仅仅反映不明确的参数的全面效果,并且结果不能为某个参数影响和贡献被屏蔽。在这研究,基于NPP的地板反应系列的动态分析,为各种各样的不明确的参数的估计的影响的一个全面索引被介绍并且推荐,包括关联系数,回归斜坡系数和旋风秋千。在NPP地震标准补偿指导的缺乏,建议方法能有效地被用来从敏感,尖酸和统计秋千的方面评估各种各样的参数的贡献关联。最后,例子被提供从系统、直觉的观点验证指示物的集合,例如NPP的皇家学会会员的结构参数和贡献的影响的无常。这个索引对参数的不同类型敏感,它为评估为NPP要求的抗地震的参数提供一种新技术。
简介:Thispaperaddressesthefreetransversevibrationsofthinsimplysupportednonhomogeneousisotropicrectangularplatesofbilinearlyvaryingthicknesswithelasticallyrestrainededgesagainstrotation.TheGram-Schmidtprocesshasbeenusedtogeneratetwo-dimensionalboundarycharacteristicorthogonalpolynomials,whichhavebeenusedintheRayleigh-Ritzmethodtostudytheproblem.Thelowestthreefrequencieshavebeencomputedforvariousvaluesofnonhomogeneousparameters,thicknessparameters,aspectratioandflexibilityparameters.Acomparisonoftheresultswiththoseavailableintheliteraturehasbeenmade.Three-dimensionalmodeshapesforthespecifiedplatehavebeenpresented.