Improved stability criteria for neutral type Lur’e systems with time-varying delays

In this letter, the problem of stability analysis for neutral type Lur’e systems with interval time-varying delays is considered. By introducing a novel Lyapunov–Krasovskii (L–K) functional and utilizing second order reciprocal convex combination technique and Finsler lemma, an improved delay-dependent stability criteria is derived in terms of linear matrix inequalities (LMIs). The information about the time-varying delays and their upper bounds are fully used in the L–K functional. Finally, a numerical example is provided to illustrate the effectiveness of the proposed method.     

A method of finding the principal modes of nonlinear vibration systems and their stabilities

This paper presents a new method of finding the principal modes of nonlinear vibration systems, by means of which the problem of finding principal modes of nonlinear systems is transferred to the problem of finding real roots of a set of algebraic equations. The method is applicable to various kinds of nonlinear vibration systems with many degrees of freedom, and is simple in calculation. The paper presents another new method of analyzing the stabilities of principal modes of nonlinear systems.     

二维各向同性多孔介质的弹性动力学通解

在二维直角坐标系下,从固体位移和流体流速满足的基本方程出发,研究了二维各向同性多孔介质的弹性动力学通解.首先引入4个物理量,对固体骨架的运动方程、流体流速运动方程、连续性方程进行整理,将方程组分解成膨胀波和扭转波两部分,并利用Lur’e算子矩阵理论,获得由3个类调和函数表示的动力学通解,该通解满足全部基本方程.最后将时间项退化获得稳态通解,并证明了稳态通解的完备性.