非理想开关电容网络的组元电荷状态变量分析法

针对运放的有限增益带宽乘积给SCN带来的非理想效应,引入了非理想运放的SC电路宏模型,定义了非理想运放负端组元割集,根据非理想SCN的连接特点,通过判断各SC积木块中电容支路两端节点的连接情况,在时域和频域分别推导出了非理想SCN的组元电荷状态方程,应用实例进行了仿真,两种方法的结果对比说明了本文算法的可行性.     

多参数多状态变量离散型有势非线性稳定问题的活化方法*

本文针对多参数变量和多状态变量的离散型有势系统的非线性稳定问题,提出了活化方法,导出了活化势函数和活化平衡方程.活化方法是弹性稳定理论中Liapunov-Schmidt方法的改进和提高,它比通常的摄动方法更加一般化、规范化.活化势函数可变换成标准突变势函数,活化平衡方程可作为分岔方程.本文的研究将促进弹性稳定理论与突变理论和分岔理论的结合.     

多跨多层框架分析的状态变量传递法

取柱端位移和对应的柱端力作为状态变量,利用传递矩阵和逐段分析的方法来分析多跨多层框架。文章取框架的每一层作为一个单元,建立基本单元端部的状态变量到相邻单元端部状态变量之间的转换关系。分析过程中,框架层数的增加仅增加矩阵相乘的次数,而待求的基本未知量的数目始终保持不变,从而提高了计算机分析问题的能力     

A continuum damage model for piezoelectric materials

In this paper, a constitutive model is proposed for piezoelectric material solids containing distributed cracks. The model is formulated in a framework of continuum damage mechanics using second rank tensors as internal variables. The Helrnhotlz free energy of piezoelectric mate- rials with damage is then expressed as a polynomial including the transformed strains, the electric field vector and the tensorial damage variables by using the integrity bases restricted by the initial orthotropic symmetry of the material. By using the Talreja＇s tensor valued internal state damage variables as well as the Helrnhotlz free energy of the piezoelectric material, the constitutive relations of piezoelectric materials with damage are derived. The model is applied to a special case of piezoelectric plate with transverse matrix cracks. With the Kirchhoff hypothesis of plate, the free vibration equations of the piezoelectric rectangular plate considering damage is established. By using Galerkin method, the equations are solved. Numerical results show the effect of the damage on the free vibration of the piezoelectric plate under the close-circuit condition, and the present results are compared with those of the three-dimensional theory.     

一种改进的电压暂降概率评估方法

针对电压暂降随机预估中传统蒙特卡洛法认为线路长度是影响线路故障率唯一影响因素的缺陷,提出了一种改进的电压暂降概率评估方法.构建了包含线路自身属性及多种客观因素的线路故障概率评估体系;并结合该评估体系,建立了完善的短路故障模型,在PSCAD/EMTDC搭建IEEE-30节点系统仿真模型,运用随机数发生模块和Multiple Run组件对故障信息进行抽样和传送,通过仿真计算得到敏感负荷接入点的电压暂降特征量和评估指标的概率分布.仿真结果表明,改进的蒙特卡洛法相比于蒙特卡洛法在电压暂降概率评估中更接近电网的真实状况,验证了该方法的有效性.     

一种新的混沌掩盖保密通信方案

提出了反馈式多变量混沌掩盖保密通信方案，理论研究及计算机模拟表明，该方案极大地改善了通信效果，其安全性和可靠性优于一般的混沌掩盖通信方案。     

Symplectic multi-level method for solving nonlinear optimal control problem

By converting an optimal control problem for nonlinear systems to a Hamiltonian system,a symplecitc-preserving method is proposed.The state and costate variables are approximated by the Lagrange polynomial.The state variables at two ends of the time interval are taken as independent variables.Based on the dual variable principle,nonlinear optimal control problems are replaced with nonlinear equations.Furthermore,in the implementation of the symplectic algorithm,based on the 2N algorithm,a multilevel method is proposed.When the time grid is refined from low level to high level,the initial state and costate variables of the nonlinear equations can be obtained from the Lagrange interpolation at the low level grid to improve efficiency.Numerical simulations show the precision and the efficiency of the proposed algorithm in this paper.     

动态规划方法中应注意的两个问题

本文从理论与实际两个方面论述了在使用动态规划方法时应注意的两个问题，即目标函数的可分性和状态变量的无后效性。分析了这两个问题在理论上的意义，提出了在实际应用中如何处理这两个问题的方法，最后举出了计算实例。对理论和实际工作者都有一定的参考价值。     

转变状态变量有源RC滤波器为电流模式滤波器的方法

给出了一种把状态变量有源RC滤波器转换成相应电流模式滤波器的新方法-替换法,并从理论上论证了替换法的正确性和可行性,还给出了将有源RC状态变量滤波器转换成由电流传送器构成的相应电流模式滤波器的具体转换程序和实例。