压电热弹性体混合层合板的响应分析

根据广义Hamilton变分原理推导出了压电热弹性体非齐次的Hamilton正则方程.考虑热平衡方程与导热方程中变量的对偶关系,通过增加正则方程的维数,成功地将非齐次的正则方程转化为能独立求解的压电热弹性体耦合问题的齐次方程.将非齐次方程转化为齐次方程不仅使问题变得大为简化,同时也减少了数值计算的工作量.数值实例研究了温度载荷和力载荷作用下压电热弹性材料四边简支层合板的响应问题,部分算例与相关文献进行了比较.     

利用广义内作用矩阵对多变量非最小相位系统进行最小相位/全域通分解

对于任意可检测和左可逆多变量非最小相位系统, 给出了其最小相位 /全域通分解的显示解. 本文的结果表明全域通因子是系统的广义内作用矩阵的逆矩阵. 因此, 直接求解系统的广义内作用矩阵便可得到上述频域分解的显示表达式. 由于本文的方法是频域法, 它可以成为对现有时域法的补充.     

变质量力学系统的Herglotz型Lagrange方程与Noether对称性和守恒量

Herglotz变分原理提供了非保守耗散问题的变分描述，同时变质量力学在自然界和工程领域有大量的应用，因此将Herglotz变分原理应用于变质量力学系统的Lagrange方程与守恒律研究，为研究变质量力学提供了一个新的途径.文中建立了变质量力学系统的Herglotz型广义变分原理，导出了变质量系统的Herglotz型Lagrange方程.定义了变质量力学系统的Herglotz型Noether对称性，建立并证明了Herglotz型Noether定理及其逆定理.文末给出两个变质量非保守系统的具体例子以说明结果的应用.     

预测控制算法的改进

通过分析非参数模型得出非参数模型容易建模,而广义预测控制在线滚动优化计算量小的特点.结合非参数模型和广义预测控制的优点,在最小绝对值误差辨识的基础上,提出了一种冗余参数模型预测控制算法,从而使得在线计算量大为减少.由于参数化模型有冗余参数,无须掌握有关模型结构和系统纯时延的确切的先验知识,不仅给建模带来极大的方便,而且有利于提高预测模型的精度和鲁棒性.     

事件空间中非完整力学系统的Herglotz-d′Alembert原理与守恒律

研究事件空间中非完整力学系统的Herglotz型守恒律.给出事件空间中Herglotz型广义变分原理,引入非完整约束并采用交换关系的H9lder定义,导出事件空间中非完整力学系统的新型微分变分原理—Herglotz-d′Alembert原理.引进事件空间中的空间生成元和参数生成元,建立Herglotz-d′Alembert原理不变性条件的变换.基于该原理构建了事件空间中非完整非保守力学系统的Herglotz型守恒定理及其逆定理.作为特例,给出了位形空间的Herglotz型守恒量和事件空间中完整力学系统的Herglotz型守恒量.文末还给出了一个算例.     

非最小相位系统的PID型广义预测自校正控制器

本文将被控对象的零点分解为非最小相位项和最小相位项,建立新的预测方程,在对一般预测控制目标函数改进的基础上加入抑制超调的预测控制量和模型误差修正,得到能抑制非最小相位系统超调的PID型广义预测自校正控制器。仿真结果表明,该算法极大地改善了控制性能,提高了系统瞬态响应。     

零点配置与一类非线性广义系统的状态反馈控制

针对状态空间实现为非最小相位的非线性广义系统的控制问题,提出一种非线性广义系统的状态空间实现算法,构建了一个等价于原输出函数的综合输出函数,能任意配置状态空间实现的传输零点,使该状态空间实现为最小相位的.所构建的最小相位输出函数能直接用于构造状态反馈控制器,实现对非线性广义系统状态反馈控制.将所得结论应用于Logistic增长的SIR传染病模型,仿真结果表明了所提方法的有效性和可行性.     

《动力学与控制学报》2007年总目次

时间-空间混和有限元……………………………………………………钟万勰高强(2007,5(1):1)广义非保守系统的新型最小作用量原理………………………赵淑红梁立孚乔水芬(2007,5(1):8)基于主动控制的三维自治混沌系统的异结构反同步……………………王兴元王勇(2007,5(1):13)Qi四维系统的暂态混沌现象……………………………………王琳倪樵黄玉盈(2007,5(1):18)极限环高阶分岔控制……………………………………………吴志强张建伟王喆(2007,5(1):23)混合Cable-Mass动力系统的一致稳定性………………………………呼青英张宏伟(2007,5(1):27)碰…     

不确定性离散时间系统非保守自适应鲁棒控制

研究含未知干扰和互质因子摄动离散时间不确定性系统的自适应鲁棒控制问题，为非保守的自适应鲁棒镇定提出一种广义参数递推估计方法，基于确定性等价原理，并利用ι1设计方法提出一种自适应鲁棒控制策略，证明了自适应算法的全局收敛性，给出了一个可验算的鲁棒稳定性条件，证明了该鲁棒稳定性条件是非保守和最优的。     

广义系统的最小实现问题

本文利用传递函数对偶的概念,给出了非真有理分式阵的实现算法和最小实现算法,提出了广义系统的最小实现定理和最小实现之间的强等价定理。     

Sensitivity analysis of the linear nonconservative systems with fractional damping

In this paper, the influence of small structural perturbation on a linear, nonconservative dynamical system exhibiting fractional bifurcation was investigated. In considering design problems for nonconservative systems, the integral structural characteristics as fundamental frequencies, critical loads for instability, and the sensitivity analysis play an important part. In this paper, the influence of small perturbation on a linear, nonconservative dynamical system exhibiting a flutter type bifurcation was investigated. The hereditary damping is described by means of fractional derivatives. To study the dynamical instability for nonconservative governing equations with fractional damping, the method of auxiliary eigenvalue problem is applied. The stability conditions of generalized Lyapunov type for the system with hereditary damping were derived. A new analytical framework for the coupled optimization of aero-structural, fractionally damped systems is presented. The approach to obtain aerodynamic sensitivities is based on adjoint systems.     

Preconditioned methods for simulations of low speed compressible flows

A time-derivative preconditioned system of equations suitable for the numerical simulation of inviscid compressible flow at low speeds is formulated. The preconditioned system of equations are hyperbolic in time and remain well-conditioned in the incompressible limit. The preconditioning formulation is easily generalized to multicomponent/multiphase mixtures. When applying conservative methods to multicomponent flows with sharp fluid interfaces, nonphysical solution behavior is observed. This stimulated the authors to develop an alternative solution method based on the nonconservative form of the equations which does not generate the aforementioned nonphysical behavior. Before the results of the application of the nonconservative method to multicomponent flow problems is reported, the accuracy of the method on single component flows will be demonstrated. In this report a series of steady and unsteady inviscid flow problems are simulated using the nonconservative method and a well-known conservative scheme. It is demonstrated that the nonconservative method is both accurate and robust for smooth low speed flows, in comparison to its conservative counterpart.     

Order,degree, and complexity

The order of a system not in state-space form has been defined elsewhere. Degree has been defined for rational transfer function matrices, and by extension to systems of least order : this definition is generalized for systems not having least order. A new concept of ‘ complexity ’ is introduced, and these ideas are used to resolve a confusion which exists in the literature.     

Extended variational formulations and F.E. models for nonlinear beams under nonconservative loading

For nonconservative mechanical systems, classical variational principles do not hold true; hence the principle of incremental virtual work is usually taken as a convenient foundation for finite element solution methods [2,8,9]. Recent results on the so-called ‘inverse problem’ of calculus of variations, however, lead to ‘extended’ variational formulations, which can be provided even for nonconservative systems. In the present paper, this approach is used for the particular case of a nonlinear beam subjected to a co-planar follower static loading. Suitable finite element models are deduced from the ‘extended’ variational principle, and their numerical performance is assessed by means of some meaningful examples.     

On least squares algorithms for system parameter identification

A new least squares solution for obtaining asymptotically unbiased and consistent estimates of unknown parameters in noisy linear systems is presented. The proposed algorithms are in many ways more advantageous than generalized least squares algorithm. Extensions to on-line and multivariable problems can be easily implemented. Examples are given to illustrate the performance of these new algorithms.     

Principle of feedback with additive system disturbances and some compensator schemes

The most complete form of control systems corresponding the principle of duality is given. Established is a new principle of feedback with additive system disturbances which permits to put in practice the optimal system variables in the case when they cannot be realized by using the feedback principle. Some other schemes of closed-loop systems are studied and generalized. The corresponding examples are given.     

平面框架结构折线型弹塑性动力学非传统Hamilton型增量变分原理

根据古典阴阳互补和现代对偶互补的基本思想,通过罗恩提出的一条简单而统一的新途径,系统地建立了平面框架结构折线型弹塑性动力学的各类非传统Hamilton型变分原理.文中首先给出平面框架结构折线型弹塑性动力学的广义虚功原理的表式,然后从该式出发,不仅能得到平面框架结构折线型弹塑性动力学的虚功原理,而且通过所给出的广义Legendre变换,还能系统地成对导出平面框架结构折线型弹塑性动力学的5类变量分原理的互补泛函,以及1类变量和相空间非传统Hamilton型变分原理的泛函.同时,通过这条新途径还能清楚地阐明这些原理的内在联系.     

Generalized normal form for rewriting P systems

P systems, introduced by Gh. Păun [9] as a new theoretical model for molecular computations, are based on the notion of membrane structure. Several variants of P systems have been proposed and shown to be computationally universal. One of such variant is the rewriting P systems, where we consider string-objects and process them using rewriting rules. Particular cases of normal forms for rewriting P systems were proposed in [11–13]. In this work we introduce the generalized normal form for rewriting P systems which take into consideration the depth of the membrane structure and the number of rewriting rules present in each membrane. Such generalized normal forms are given for rewriting P systems with priorities, and for partially parallel rewriting P systems. In this way, several results from the literature are generalized and improved. Received: 14 March 2002 / 5 June 2002     

广义信息系统的属性约简

把完备信息系统、不完备信息系统、序信息系统、覆盖信息系统等常见信息系统统称为广义信息系统,采用新的知识表达形式将其知识结构进行统一表示,特别是将覆盖信息系统纳入了广义信息系统的框架之中。在广义信息系统中引入粒度熵的概念,对属性的重要性给出度量;在此基础上,提出一种广义信息系统属性约简的启发式算法,进而得到广义信息系统的知识约简,并给出了若干算例。