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11 个结果
  • 简介:Thedirect-forcingfictitiousdomainmethodisextendedtosimulatethelocomotionofapassivelypitchingfoil.Ourstudyfocusesonthehysteresisphenomenonthatthecriticalfrequencyforthereverseofthelocomotiondirectionofthewingincaseofdecreasingfrequencyissmallerthanthatincaseofincreasingfrequency.Inoursimulations,thehysteresisphenomenonisproducedbyimposingdifferentinitialconditionsatasamefrequency.Ourresultsindicatethattheratiooftheheavingamplitudesoftwofoiledgesiscrucialtothedirectionofthefoil'shorizontalmotion,andtheamplitudeoftheleadingedgeisgenerallysmaller.Thecriticalfrequenciesforthereverseofthelocomotiondirectionareincreased,whenthefoil-fluiddensityratioisdecreasedorthespringconstantisincreased.Thecriticalfrequenciesinthebi-stabilityregimealsodependontheinitialvelocityimposed,andthehysteresisloopgenerallybecomeslargeriftheinitialvelocitiesareclosertotheterminallocomotionvelocitiesofthefoil.

  • 标签: 运动方向 滞后现象 数值研究 临界频率 俯仰 初始速度
  • 简介:马氏体域形成,进化和歼灭广泛地在superelasticNiTi多晶的形状存储器合金的导致压力的阶段转变被观察。由热力学的驱动力的计算和接口的磨擦动力学的加入,领域形态学和它的进化被追踪接口的技术成功地模仿。计算结果与张力的脱衣的试验性的观察同意很好。基于理论、计算的结果,我们在在不同领域模式之间的转变上讨论了批评驱动力和metastability的存在的效果。

  • 标签: 应力诱导 热演化 镍钛形状记忆合金 热力学驱动力 张力 域名
  • 简介:Backlash-likehysteresisisoneofthenonsmoothandmulti-valuednonlinearitiesusuallyexistinginmechanicalsystems.Thetraditionalidentificationmethodisquitedifficulttobeusedtomodelthesystemsinvolvedwithsuchcomplexnonlinearities.Inthispaper,anonsmoothrecursiveidentificationalgorithmforthesystemswithbacklash-likehysteresisisproposed.Inthismethod,theconceptofClarkesubgradientisintroducedtoapproximatethegradientsatnonsmoothpointsandtheso-calledbundlemethodisusedtoobtaintheoptimizationsearchdirectioninnonsmoothcases.Then,arecursivealgorithmbasedontheideaofbundlemethodisdevelopedforparameterestimation.Afterthat,theconvergenceanalysisofthealgorithmisinvestigated.Finally,simulationresultstovalidatetheproposedmethodonasimulatedmechanicaltransmissionsystemarepresented.

  • 标签: IDENTIFICATION Mechanical system Pseudo-Hammerstein model BACKLASH
  • 简介:Investigationintothemagnetswithdifferentsquarenessofhysteresisloop(SHL)revealsthatthemicrostructureofsinteredNdFeBmagnetshasgreateffectsontheSHLofthemagnets.TheabnormalgraingrowthdeterioratestheSHLseriously.Theshapeofthegrainandthegrainboundaryaffecttheintensityofdemagnetizationfield,andconsequentlyontheSHL.Theaddedelementshaveeffectsonthephasestructuresanddistributionsinthemagnets,whichinfluencestheuniformofdemagnetizationfield.

  • 标签: NDFEB SQUARENESS of HYSTERESIS loop ABNORMAL
  • 简介:Controlmethodsofhysteresiscurrentvectorcontrolofpermanentmagnetsynchronousservodrivefedbyvoltagesourceinverterareexamined.Detaileddescriptionofthecontrolmethodsinstationaryreferenceframewithcircle,squareandhexagonshapetoleranceareausingadaptivesolutionsispresented.Thetheoreticalconsiderationsaresupportedbysimulationresults.

  • 标签: 电流矢量控制 伺服驱动器 形状自适应 控制同步 滞环 公差
  • 简介:根据输入的开车的率更新参数,率依赖者Prandtl-Ishlinskii(PI)模型广泛地在磁滞现象建模和赔偿被使用。以便改进当模特儿的精确性,独立以低、高的开车的率识别的二个PI模型通过一条联合法律被合并。为驾驶piezo的基于弯曲的机制,低抑制比率使使结构的颤动激动容易。作为结果,测量磁滞现象环极大地被弄歪,识别PI模型的当模特儿的精确性显著地被影响。在这份报纸,作为控制输入利用附加正弦曲线信号的一个新奇时间有效的参数鉴定方法被建议。这个方法有效地避免结构的颤动的刺激。另外,作为附加正弦曲线信号的开车的率盖住一个宽范围,为为率依赖建模要求的所有系数能通过仅仅试验性的数据的一个集合被识别。当模特儿的磁滞现象和追踪实验的轨道在2-DOF上被执行驾驶piezo的基于弯曲的机制。试验性的结果证明联合磁滞现象模型在基于弯曲的机制的全部工作范围上维持当模特儿的精确性。机制磁滞现象被反的PI模型的使用显著地作为前馈控制控制器压制;并且当一个反馈环也被合并时,更好的结果被完成。基于弯曲的机制的追踪的表演极大地被改进。

  • 标签: 磁滞现象建模 率依赖 压电的致动器 基于弯曲的机制
  • 简介:Adual-stageservosystemconsistsofaprimarycoarseactuatorforfacilitatinglargemotionandasecondarymicro-actuatorforsmallbutprecisemotiontoimprovetrackingperformance.Piezoelectricmicro-actuatormadefromleadzirconatetitanate(PZT)hasbeenapopularchoiceforthesecondarystage.However,theadvantagegainedbytheresolutionofthesecondaryPZTactuatorisreducedbyitsinherenthysteresisnonlinearity.Modelbasedhysteresiscompensationtechniquesarepreferredduetotheirsimplicityandfastresponse.Identificationandmodelingaretwosubstantialpartsinsuchmodel-basedtechniques.ThispaperpresentsarigorousanalysisandmodelingofthehysteresisofPZTmicro-actuator.ModifiedGeneralizedPrandtl-IshlinskiiandColeman-Hodgdonmodelsarestudied.Identificationofthemodelthroughnonlinearleastsquareandparticleswarmoptimizationareexaminedandcompared.Severalanalysesaredonethroughtuningofthemodelparametersandidentificationtechniques.Experimentalanalysisandsimulationresultsunderscoretheeffectivenessofthismodelingapproach.Finallyasadesignexample,adual-stagesimulationanalysisisdonetoshowtheeffectivenessofsystematicmodelingonhysteresiscompensation.

  • 标签: HYSTERESIS particle SWARM optimization(PSO) modified generalized