简介:Thepressurereflectedfromabi-laminatedpiezoelectricplatehasbeendeterminedusingtheThomson-Haskellmatrixmethod.Theplateiscomposedofapiezoelectriclayerwithgroundedvacuumandanelasticlayerincontactwiththefluid.Anincidentplanewaveinthefluidmediumstrikestheplateatdif-ferentangles.Therequiredelectricpotentialacrossthepiezoelectriclayertocancelthereflectionfromthefluid/elasticboundaryhasbeendeterminedforthepiezoelectricmaterialPZT-5atvariousthicknessparame-lersandincidentfrequencies.
简介:ByapplyingtheHeavisidefunction,theequationsgoverninglaminatedplatespossess-ingspatiallydistributedpiezoelectricpatcheshavebeenestablished.Basedontheseequations,staticshapecontroloflaminatedplatesisdiscussed.Byusingageneticandcollocationalgorithm,theopti-mallocationsandscalesofthesepiezoelectricpatcheshavebeenselected.Numericalexamplesarepre-sentedtoillustratetheefficiencyofthealgorithmandthepiezoelectricactuators.
简介:Anewstochasticoptimalcontrolstrategyforrandomlyexcitedquasi-integrableHamiltoniansystemsusingmagneto-theological(MR)dampersisproposed.ThedynamicbehaviorofanMRdamperischaracterizedbytheBouc-Wenhystereticmodel.ThecontrolforceproducedbytheMRdamperisseparatedintoapassivepartincorporatedintheuncontrolledsystemandasemi-activeparttobedetermined.ThesystemcombiningtheBouc-Wenhystereticforceisconvertedintoanequivalentnon-hystereticnonlinearstochasticcontrolsystem.ThenItostochasticdifferentialequationsarederivedfromtheequivalentsystembyusingthestochasticaveragingmethod.Adynamicalprogrammingequationforthecontrolleddiffusionprocessesisestablishedbasedonthestochasticdynamicalprogrammingprinciple.Thenon-clippingnonlinearoptimalcontrollawisobtainedforacertainperformanceindexbyminimizingthedynamicalprogrammingequation.Finally,anexampleisgiventoillustratetheapplicationandeffectivenessoftheproposedcontrolstrategy.
简介:Thispaperpresentsananalysisoftheactivecontrolofrandomvibrationforlaminatedcompositeplatesusingpiezoelectricfiberreinforcedcomposites(PFRC).WithHamilton’sprincipleandtheRayleigh-Ritzmethod,theequationofmotionfortheresultingelectromechanicalcouplingsystemisderived.Avelocityfeedbackcontrolruleisemployedtoobtainaneffectiveactivedampinginthesuppressionofrandomvibration.Thepowerspectraldensityandmeansquaredisplacementsoftherandomvibrationforlaminatedplatesunderdifferentcontrolgainsaresimulatedandthevalidityofthepresentcontrolstrategyisconfirmed.TheeffectofpiezoelectricfiberorientationinthePFRClayerontherandomvibrationsuppressionisalsoinvestigated.Theanalyticalmethodologycanbeexpandedtootherkindsofrandomvibration.
简介:Theeffectivenessofafluid-loadedsandwichedviscoelasticlayerinsuppressingacousticscat-teringandradiationhasbeenestimatedusingtheThomson-Haskellmatrixmethod.TheGU(GaunaurdandUberall)resonancetheoryhasbeenadoptedtohandlethreetypesofviscoelasticsubstrateswithair-filledin-clusions.Theeffectsofthevaryingthicknessofthesubstrates,thevolumefractionsoftheinclusionsandfre-quenciesofincidentwaveshavebeenstubbedtodeterminetheoptimalstrategiesofsignalreduction.Intheinvestigation,themonopoleresonancephenomenaoftheinclusionshavebeentakenintoaccount.
简介:BasedontheFloquettheoryonordinarydifferentialequationswithperiodicallyvariablecoefficientsandthebifurcationapproachtononlinearequations,anumericalapproachtodeterminingthestabilityregionofcontrolparametersisestablishedforadynamiccontrolsystemcomposedofamovingbodylevitatedmagneticallyoverflexibleguideways.Thesystemisnonlinearlycoupledamongtheelasticdeformationofguideways,disturbancethelevitationpositionofthebodyandelectromagneticcontrolforces.Thenumericalsimulationisgivenforthesysteminthecaseinwhichthecontrolparametersaretakenwithinandoutofthestabilityregionrespectively.Resultsshowthatthisapproachisreliable.
简介:为在有致动器浸透的非白种人的宽带随机刺激下面的强烈非线性的系统的围住的最佳的控制策略被建议。首先,随机的平均方法用概括泛音功能在宽带随机刺激下面为控制强烈非线性的系统被介绍。然后,为浸透的控制问题的动态编程方程被提出从部分平均它吗?方程基于动态编程原则。由无界的最佳的控制组成的最佳的控制和围住的枪战影片控制被解决动态编程方程决定。最后,最佳地控制的系统的反应被解决方程与联系了的减少的Fokker-Planck-Kolmogorov(FPK)预言完成平均它吗?方程。一个例子被给说明建议控制策略。数字结果证明建议控制策略有高控制有效性和效率并且啁啾显著地被减少与枪战影片作比较控制策略。