简介:Inthispaper,twoirreversibleexothermicautocatalyticreactionswhichcarryoutincontinuousstirredtankreactor(CSTR)areconsidered.Adifferential-algebraicsystemisappliedtomodelthesechemicalreactions.Thestabilityandthedynamicbehaviorarestudiedforthedifferential-algebraicsystem.TheHopfbifurcationappearswhentheparameterexceedsacriticalvalue.Inordertoeliminatethiscomplexbehavior,thedifferential-algebraicsystemisdescribedbyasingle-inputandsingle-outputsystemwithparametervaryingwithindefiniteintervals,andthenvariablestructurecontrolwithslidingmodebasedonaspecialpowerreachinglawisdesignedtostabilizethischemicalsystem.Numericalsimulationsaregiventoillustratetheeffectivenessofthemethod.
简介:Contact-impactprocessesoccuratmostcasesinmultibodysystems.Sub-periodsandsub-regionalmethodsarefrequentlyusedrecently,anddifferentcoordinatesareintroducedinbothoftheapproaches.However,thesub-regionalmethodseemstobemoreeffective.Floatingframeofreferenceformulationiswidelyusedforcontacttreatment,whichdescribesdisplacementsbytherigidbodymotionandasmallsuperposeddeformation,andthecoordinatesdepictingthedeformationincludefiniteelementnodalcoordinatesandmodalcoordinates,theformerdealswiththecontact/impactregion,andthelaterdescribesthenon-contactregion.Inthispaper,freeinterfacesubstructuremethodisusedinmodeling,andthedynamicequationofasinglebodyisderived.Then,usingtheLagrangeequationofthefirstkind,thedynamicequationsofmultibodysystemsareestablished.Furthermore,contact-impactareasaretreatedthroughadditionalconstraintequationsandLagrangemultipliers.Usingsuchapproach,thenumberofsystemcoordinatesandthedimensionsofmassmatrixaresignificantlyreducedwiththemodaltruncation,thereforebothoftheefficiencyandaccuracyareguaranteed.Finiteelementmethodinthelocalcontactregioncandealwithcontact/impactbetweenarbitrarilycomplexinterfaces,whereas,additionalcontactconstraintsusedinthenodaldescriptionregioncanavoidthecustomizedparametersthatareusedinthecontinuousforcemodel.
简介:Large-scalewindturbinegeneratorsystemshavestrongnonlinearmultivariablecharacteristicswithmanyuncertainfactorsanddisturbances.Automaticcontroliscrucialfortheefficiencyandreliabilityofwindturbines.Onthebasisofsimplifiedandpropermodelofvariablespeedvariablepitchwindturbines,theeffectivewindspeedisestimatedusingextendedKalmanfilter.Intelligentcontrolschemesproposedinthepaperincludetwoloopswhichoperateinsynchronismwitheachother.Atbelow-ratedwindspeed,theinnerloopadoptsadaptivefuzzycontrolbasedonvariableuniverseforgeneratortorqueregulationtorealizemaximumwindenergycapture.Atabove-ratedwindspeed,acontrollerbasedonleastsquaresupportvectormachineisproposedtoadjustpitchangleandkeepratedoutputpower.Thesimulationshowstheeffectivenessoftheintelligentcontrol.
简介:这份报纸在通常在实验经济研究被遇到的endogeneity的存在在一个二阶段的最少的广场(2SLS)模型的结构的方程学习可变选择问题。在结构的方程的模型无常和可变选择是在安德鲁斯和陆和Caner(2009)(2001)描述了的一个重要问题。作者与endogeneity为线性结构的方程建议一个适应套索2SLS评估者并且证明它享受神谕性质,即,在评价和模型的一致性选择。在蒙特卡罗模拟,作者证明建议评估者与桥类型GMM评估者相比有更小的偏爱和MSE(Caner,2009)。在案例研究,作者重游经典回来到教育问题(Angrist和Krueger,1991)用中国人口普查数据。作者发现教育铺平不仅在收入上有强壮的效果而且在不同年龄队显示出异质。
简介:现在的学习探讨能改进驱逐者效率并且在固定操作压力比率下面控制再通行比率的一个可变驱逐者。可变驱逐者是一台设备由改变驱逐者喉咙区域比率在给定的操作压力比率下面获得特定的再通行比率。数字模拟被执行在可变驱逐者内提供流动特征的理解。声音、超声的嘴在驱逐者系统,和活动的锥柱体作为主要的开车的嘴被采用,插入了到一个常规驱逐者弥漫的系统,被用来改变驱逐者喉咙区域比率。数字模拟基于可压缩的、平均Reynolds的海军司烧方程的一个充分含蓄的有限体积计划。结果证明可变驱逐者能在固定操作压力比率控制再通行比率。关键词可变驱逐者-驱逐者喉咙区域比率-再通行比率CLC数字O358
简介:WeconsiderHardyspaceswithvariableexponentsdefinedbygrandmaximalfunctionontheHeisenberggroup.ThenweintroducesomeequivalentcharacterizationsofvariableHardyspaces.ByusingatomicdecompositionandmoleculardecompositionwegettheboundednessofsingularintegraloperatorsonvariableHardyspaces.WeinvestigatetheLittlewood-Paleycharacterizationbyvirtueoftheboundednessofsingularintegraloperators.
简介:Inthispaper,theauthorsintroducecertainHerztypeHardyspaceswithvariableexponentsandestablishthecharacterizationsofthesespacesintermsofatomicandmoleculardecompositions.Usingthesedecompositions,theauthorsobtaintheboundednessofsomesingularintegraloperatorsontheHerztypeHardyspaceswithvariableexponents.
简介:Inthispaper,weconsidertheboundarystabilizationofthewaveequationwithvariablecoefficientsbyRiemmanniangeometrymethodsubjecttoadifferentgeometricconditionwhichismotivatedbythegeometricmultiplieridentities.Several(multiplier)identities(inequalities)whichhavebeenbuiltforconstantwaveequationbyKormornikandZuazuaaregeneralizedtothevariablecoefficientcasebysomecomputationaltechniquesinRiemmanniangeometry,sothatthepreciseestimatesontheexponentialdecayratearederivedfromthoseinequalitities.Also,theexponentialdecayforthesolutionsofsemilinearwaveequationwithvariablecoefficientsisobtainedundernaturalgrowthandsignassumptionsonthenonlinearity.Ourmethodisrathergeneralandcanbeadaptedtootherevolutionsystemswithvariablecoefficients(e.g.elasticityplates)aswell.
简介:可变几何学捆绑操纵者(VGTM)有潜力在未来空间应用程序,一个动态模型对系统的动态分析和控制重要工作。在这份报纸,一条途径被介绍由独立变量为VGTM的动态方程建模,它由二双octahedral组成捆绑单位和3-revolute-prismatic-spherical(3-RPS)平行操纵者。在这条途径,二邻近的身体的运动学的递归的关系并且几何抑制被用来推出VGTM的运动学的方程,并且Jourdains速度变化原则被采用建立系统的动态方程。建议动态模型的有效性被数字模拟的比较与软件亚当斯验证。而且,为轨道追踪系统的一个活跃控制器被计算转矩方法设计。控制器的有效性数字地被证明。
简介:TheRitzprojectionsoftheellipticproblem(?)(aij(?)ju)+c0u=finΩ,u=0on(?)Ω,andthequasilineareilipticproblem(?)(ai(x,Du))+a0(x,Du)=0inΩ,u=0on(?)Ωwithlinearfiniteelementsadmitanasymptoticerrorexpansion,respectively,forcertainclassesof“uniform”meshes.ThisprovidesthetheoreticaljustificationfortheuseofRichardsonextrapolationforincreasingtheaccuracyoftheschemefromO(h2)toO(h4|lnh|).
简介:ThispaperinvestigatesnumericallytheinherentirreversibilityinunsteadygeneralizedCouetteflowbetweentwoparallelplateswithvariableviscosity.ThenonlineargoverningequationsarederivedfromtheNavier-Stokesequationsandsolvednumericallyusingasemi-discretizationfinitedifferencemethodtogetherwiththeRunge-Kutta-Fehlbergintegrationscheme.Theprofilesofvelocityandthetemperatureobtainedareusedtocomputetheentropygenerationnumber,Bejannumber,skinfrictionandNusseltnumber.Theeffectsofembeddedparametersonentireflowstructurearepresentedgraphicallyanddiscussedquantitatively.