稳定化的有限频段H∞控制及有限频段跟踪问题

基于GKYP引理的动态输出反馈设计,未保证设计后闭环系统的稳定性。针对以小增益作为指标的有限频段动态输出反馈问题,在不增加新变量的前提下,增加稳定性约束,使得设计后的闭环系统渐近稳定且满足有限频段性能指标。针对增加约束后难以找到可行解的情况,基于零空间条件的不惟一性,补充了另一种零空间条件,从而扩大了问题的可行域。将改进后的方法应用于有限频段跟踪问题的研究,通过仿真例子验证,有限频段动态输出反馈虽然存在保守性,但在合理选择基矩阵R的情况下,仍然可以使得其保守性小于传统的全频段最优H∞控制的保守性。     

A pumping lemma for random permitting context languages

Random context grammars belong to the class of context-free grammars with regulated rewriting. Their productions depend on context that may be randomly distributed in a sentential form. Context is classified as either permitting or forbidding, where permitting context enables the application of a production and forbidding context inhibits it. For random context languages of finite index a generalization of the well-known pumping lemma for context-free languages has been proven. We drop the finite index restriction and concentrate on non-erasing grammars that use permitting context only. We prove a pumping lemma for their languages that generalizes and refines the existing one, and show that these grammars are strictly weaker than the non-erasing random context grammars.     

电力系统外部等值网络快速修正方法

在基于外部静态等值的电力系统最优潮流计算中,为了保持外部等值精度,不断重新计算外部等值导纳矩阵将导致优化计算时间效率下降,文中针对Ward外部等值方法的特点,从不同解决思路入手,分别采用矩阵求逆辅助定理和支路等值注入功率模型提高外部等值网络参数修正计算速度,对两种快速修正方法的修正原理和计算过程做了充分的分析和说明,以IEEE 39节点系统和某538节点系统作为试验系统,验证所提方法的有效性,并对两种修正方法进行详细分析比较.     

An improved finite frequency approach to robust filter design for LTI systems with polytopic uncertainties

In this paper, the finite frequency robust filtering problem (‐FFRFP), design of a robust filter minimizing the norm from the disturbance input to the estimation error evaluated over a prescribed finite frequency domain, is considered for continuous‐time and discrete‐time linear time‐invariant (LTI) systems with polytopic parameter uncertainties. By means of the generalized Kalman–Yakubovich–Popov (KYP) lemma in combination with a result known as Finsler's lemma, the ‐FFRFP is cast as a linear matrix inequality (LMI) optimization. Examples are given to demonstrate that the proposed condition can achieve improvement over the previous ones in the literature. Copyright © 2012 John Wiley & Sons, Ltd.     

Neumann引理的一个推广及其应用

给出了经典Neumann引理的一个推广，并给出这一推广在研究算子扰动及Bessel列与框架的扰动问题中的一些应用．     

上下文无关语言的可重复序列及其性质

通过分析下推自动机的运行规律和特点,提出上下文无关语言的可重复序列的概念,将其划分为平衡重复序列、增重复序列、减重复序列三类;研究了这三类可重复序列在下推自动机的状态转换图中的结构表现和性质,通过分析下推自动机状态转换图中标注回路与可重复序列之间的关系,给出求解可重复序列的计算方法;证明了不同类型的可重复序列对上下文无关语言性质的影响,利用可重复序列揭示了上下文无关语言的Pumping引理的本质特征,并给出正规语言判定的一个充分必要条件.     

Forking引理与一类基于身份签名体制的安全性证明

在随机谕示模型下,研究一类基于身份的签名体制(称为基于身份的一般签名体制)的安全性.所得理论成果可以被看作Pointcheval和Stern提出的Forking引理在基于身份签名体制研究领域的扩展,有助于理解和简化一些现有的基于身份签名体制的安全性证明,如Cha-Cheon的体制、Hess的体制1及Cheon-Kim-Yoon的体制等.     

Nonlinear Consensus Algorithms with Uncertain Couplings

Distributed algorithms for synchronization and consensus in multi‐agent networks are considered. The agents are assumed to be linear of arbitrary order, the interaction topology may switch, and the couplings are uncertain, assumed only to satisfy certain quadratic constraints. Using the Kalman‐Yakubovich‐Popov lemma and absolute stability theory techniques, consensus criteria for the networks of this type are obtained. These criteria extend a number of known results for agents with special dynamics and are close in spirit to the celebrated circle criterion for the stability of Lurie systems.     

公差优化设计中几个引理的研究

本文得出了计算机辅助公差优化设计中有关最优解存在条件的几个引理；引入和论证了公差优化设计中有关目标函数、约束函数性质等引理；并给出了新的机加工成本──公差模型．     

退化拟线性椭圆型方程某类边值问题的广义解

本文在一定条件下证明了如下的退化拟线性椭圆型方程的边值问题: -D_1(g(|D_u|~2)D_1u)=f(x,u) x∈Ω g(|D_u|~2)D_1ucos(n,x_1)+h(x,u)=0 x∈Ω存在非平凡的广义解。