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WKBJ近似保辛吗?   总被引:3,自引:1,他引:2  
WKBJ短波近似是最常用的有效求解方法之一。保守体系的微分方程可用Hamilton体系的方法描述,其特点是保辛。保辛给出保守体系结构最重要的特性。但WKBJ短波近似却未曾考虑保辛的问题。本文给出验证近似解保辛的条件,并指出WKBJ近似难于保辛。然后给出正则变换的摄动保辛方法。数值例题展示了提出的保辛算法的有效性。  相似文献
2.
吴志刚  高强 《力学学报》2004,36(6):757-761
系统的H∞范数表征其对外界干扰的抑制能力.艰据控制系统最小H∞范数与Hamilton微分系统两 点边值问题一阶特征值之间的对应关系,利用微分方程特征值的摄动法估计由区间参数描述的不确定性系统的 最小H∞范数.  相似文献
3.
基于H∞滤波系统的最优性能指标与相应的Hamilton微分方程特征值之间的对应关系,利用微分方程特征值的摄动法研究了参数摄动H∞滤波系统的性能指标计算问题。当原滤波系统的最优性能指标已知时,利用系统参数的变化量就可以确定摄动系统的最优性能指标。  相似文献
4.
Propagation of stationary random waves in viscoelastic stratified transverse isotropic materials is investigated. The solid was considered multi-layered and located above the bedrock, which was assumed to be much stiffer than the soil, and the power spectrum density of the stationary random excitation was given at the bedrock. The governing differential equations are derived in frequency and wave-number domains and only a set of ordinary differential equations ( ODEs) must be solved. The precise integration algorithm of two-point boundary value problem was applied to solve the ODEs. Thereafter, the recently developed pseudo-excitation method for structural random vibration is extended to the solution of the stratified solid responses.  相似文献
5.
When using H∞ techniques to design decentralized controllers for large systems,the whole system is divided into subsystems, which are analysed using H∞ control theorybefore being recombined. An analogy was established with substructural analysis instructural mechanics, in which H∞ decentralized control theory corresponds to substructuralmodal synthesis theory so that the optimal H∞ norm of the whole system corresponds to thefundamental vibration frequency of the whole structure. Hence, modal synthesismethodology and the extended Wittrick-Williams algorithm were transplanted from structuralmechanics to compute the optimal H∞ norm of the control system. The orthogonality and theexpansion theorem of eigenfunctions of the subsystems H∞ control are presented in part(I) of the paper. The modal synthesis method for computation of the optimal H∞ norm ofdecentralized control systems and numerical examples are presented in part (Ⅱ).  相似文献
6.
When using H∞ techniques to design decentralized controllers for large systems, the whole system is divided into subsystems, which are analysed using H∞ control theorybefore being recombined. An analogy was established with substructural analysis instructural mechanics, in which H∞ decentralized control theory corresponds to substructuralmodal synthesis theory so that the optimal H∞ norm of the whole system corresponds to thefundamental vibration frequency of the whole structure. Hence, modal synthesismethodology and the extended Wittrick-Williams algorithm were transplanted from structuralmechanics to compute the optimal H∞ norm of the control system. The orthogonality and theexpansion theorem of eigenfunctions of the subsystems H~ control are presented in part (I)of the paper. The modal synthesis method for computation of the optimal H∞ norm ofdecentralized control systems and numerical examples are presented in part (Ⅱ).  相似文献
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将弹性力学辛对偶求解方法与Laplace变换相结合,提出了一个求解粘弹性平面问题的新方法。首先利用Laplace变换,将粘弹性平面问题转化为一个准弹性问题,在辛弹性力学的框架下,利用分离变量和辛本征展开法对其进行求解,然后由逆变换得到原问题的解。为证明方法的有效性,求解分析了矩形域平面粘弹性圣维南问题,得到了令人满意的结果。  相似文献
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