Banach空间中的微分方程的平稳振荡

近几十年来,在抽象空间中的微分方程的研究十分活跃。由于从有限维情形过渡到无限维情形发生了质的变化。因此在研究方法上,把有限维情形的一些理论和结果推广到无限维情形中去,需要建立新的概念、方法和条件。关于Banach空间中的微分方程存在唯一稳定的周期解(即存在平稳振荡)问题,人们研究很少。其困难在于Banach空间中的有界闭集不一定是紧致集。本文首先把欧氏空间中的Lasalle平稳振荡定理平行移植到Banach空间中去,然后避免使用Lasalle平稳振莎定理中的“系统有一个     

复Banach空间的单位球上Bloch-型空间之间的有界的加权复合算子

设X是有限或无限维的复Banach空间.作者刻画了X的单位球上Bloch-型空间与小Bloch-型空间之间的有界的加权复合算子,从而推广了有限维区域上的一些结果.     

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阿拉坦仓　张鸿庆　钟万勰　矩阵多元多项式的带余除法及其应用周泽宣　ＴａｎＳｏｏｎＫｅａｔ　林建忠　含悬浮固粒射流界面稳定性研究李　粤　李立希　吴学谋　泛系方法论与幻方构造陈建康　黄筑平　白树林　颗粒增强复合材料相界面的动态应力分析谢伟松　陶建华　用ＬｅｖｅｌＳｅｔ算法模拟孤立波与前台阶的相互作用孙　璐　邓学钧　运动分布荷载作用下无限大板的稳态响应武建勋　用链式模型讨论圣文南原理张英世　文克尔地基上中面单向受拉(压)的阶梯式单向矩形薄板的振动张继业　杨翊仁　曾　京　无限维关联系统的弦稳定性何吉欢　凑…     

基于动态面技术的随机非线性关联系统的输出反馈控制

针对一类参数不确定且含有未知关联项的随机非线性关联系统,提出了一种自适应输出反馈控制方案.该方案利用K滤波器估计不可量测的系统状态,将动态面技术与输出反馈控制相结合,避免了传统后推设计过程中对虚拟控制律反复求导出现的"复杂性膨胀"问题,设计的自适应动态面控制器可以确保闭环系统中的所有信号在概率意义下半全局一致终结有界,且跟踪误差收敛到一个小的残差集内.     

二维自治g-Navier-Stokes系统的全局渐近行为研究

研究了有界区域上二维自治g-Navier-Stokes系统的双全局吸引子,利用非紧性测度方法,给出了一种验证其存在性的新方法.得出二维自治g-Navier-Stokes方程在有界区域上有一个非空、紧可逆H_g一V_g全局吸引子这一结论.     

非线性广义系统最优控制的最大值原理：无限维情形

§1.引言 对于无限维非线性最优控制问题,[1]—[3]在一定条件下证明了最大值原理。在有限维情形,[4]讨论了线性广义系统的二次型指标最优问题。关于有限维非线性广义系统的讨论见[5],[6]。而对于无限维非线性广义系统的最优控制问题,目前尚无讨论。本文利用Ekeland变分原理[7]—[10]和Fattorini引理,对具有一般目标泛函的无限维广义系统的最优控制问题给出了最大值原理。     

失效单调关联系统中可存活元件的剩余寿命的混合表示

本文中研究的是由$n$个独立同分布元件构成的单调关联系统,当该单调关联系统失效时得到了系统中可存活元件的剩余寿命的可靠性函数的混合表示.基于signature的概念,对两个系统的剩余寿命进行了随机比较.     

RICCATI方程解的正向延拓与脱逸

本文给出关于有限维Riccati方程正向解有限脱逸时间的Martin命题的简单的直接证明,以典例阐明抛物型系统关联的无限维Riccati方程解的无正向延拓性,对双曲型系统关联的无限维Riccati方程利用二次最优控制的特性证明了相应的有限脱逸时间定理。     

线性连续衰退记忆系统的可分性

为逼近建模和辨识问题的需要,讨论线性时变连续有界输入有界输出稳定衰退记忆系统的不同子类．从衰退记忆系统的子类包括概周期系统,渐近周期系统,渐近强周期系统,找到了LTV系统的可分子空间即渐近强周期系统．     

具无限时滞中立型泛函微分方程解的稳定性与有界性

以相空间为基础，研究了具有无限时滞中立型泛函微分方程解的稳定性和有界性，建立了方程解为一致稳定，一致渐近稳定的充要性判据；证明了当方程右端泛函满足Lipschitz条件时，解的一致渐近稳定性蕴涵了有界解的存在性，推广了文献［4-6］中已有的相关结果.     

中立多变时滞Volterra型随机动力系统的稳定性

探讨了一类非线性随机积分微分动力系统,并通过Banach不动点方法,给出了该系统零解均方渐近稳定的充要条件,形成了中立多变时滞Volterra型随机积分微分动力系统零解均方渐近稳定性定理。与前人的研究方法不同,该文根据多变时滞随机动力系统各时滞的特点,灵活构造算子,相比以往文献的方法更加灵活实用。文章的结论一定程度上改进和发展了相关研究论文的结果。另外,文章所得结论补充并推广了不动点方法在研究非线性中立多变时滞Volterra型随机积分微分动力系统零解稳定性方面的成果。     

Global solvability and decay estimates for a type III thermo-viscoelastic coupled system with infinite memory and boundary interaction feedback

A type III thermo-viscoelastic coupled system with infinite memory and distributed delay is considered. The interaction feedback between the nonlinear damping and the acoustic conditions are reacted on portion of the boundary. We obtain the well posedness and regularity of the system by using semigroup theory which is combined with Schauder's fixed point theorem. Moreover, the general decay estimates are established under a much larger class of relaxation functions. Our results are obtained without the boundedness condition of initial data assumed in many earlier papers in the literature. This work generalizes the composite stability between infinite memory and nonlinear damping.     

Output feedback vibration control of a string driven by a nonlinear actuator

In this paper, we design an observer-based output feedback controller to exponentially stabilize a system of nonlinear ordinary differential equation-wave partial differential equation-ordinary differential equation. An observer is designed to estimate the full states of the system using available boundary values of the partial differential equation. The output feedback controller is built via the combination of the ordinary differential equation backstepping which is applied to deal with the nonlinear ordinary differential equation, and the partial differential equation backstepping which is used for the wave partial differential equation-ordinary differential equation. The controller can be applied into vibration suppression of a string-payload system driven by an actuator with nonlinear characteristics. The global exponential stability of all states in the closed-loop system is proved by Lyapunov analysis. The numerical simulation illustrates the states of the actuator, string, payload and the observer errors are fast convergent to zero under the proposed output feedback controller.     

基于滑模方法的倒立摆台车系统的非线性控制

以倒立摆台车系统为研究对象，将系统状态分成两组，构造出一种双层滑动面，给出一种基于滑模控制的非线性控制律，并设计了控制器参数．然后采用Lyapunov方法，证明了各级滑动平面的稳定性，实现了台车在水平方向位置及摆角的渐近跟踪．     

微分本构粘弹性轴向运动弦线横向振动分析的差分法

给出了微分本构粘弹性轴向运动弦线横向振动数值仿真的一种差分法．文中建立了具有微分本构的粘弹性运动弦线的横向振动模型;通过对系统的控制方程和本构方程在不同的分数节点离散,得到一种新的差分方法．利用这一方法,弦线振动方程的数值计算过程可以交替地显式进行,且有较小的截断误差和好的数值稳定性．与通用的方法比较,新的方法计算简单、方便．文中利用方程的不变量检验了数值结果的可靠性,并利用这一方法给出了一类弦线模型的参数振动分析．     

Nonlinear scheme with high accuracy for nonlinear coupled parabolic-hyperbolic system

A nonlinear finite difference scheme with high accuracy is studied for a class of two-dimensional nonlinear coupled parabolic-hyperbolic system. Rigorous theoretical analysis is made for the stability and convergence properties of the scheme, which shows it is unconditionally stable and convergent with second order rate for both spatial and temporal variables. In the argument of theoretical results, difficulties arising from the nonlinearity and coupling between parabolic and hyperbolic equations are overcome, by an ingenious use of the method of energy estimation and inductive hypothesis reasoning. The reasoning method here differs from those used for linear implicit schemes, and can be widely applied to the studies of stability and convergence for a variety of nonlinear schemes for nonlinear PDE problems. Numerical tests verify the results of the theoretical analysis. Particularly it is shown that the scheme is more accurate and faster than a previous two-level nonlinear scheme with first order temporal accuracy.     

Robust exponential stability of switched delay interconnected systems under arbitrary switching

The problem of robust exponential stability for a class of switched nonlinear dynamical systems with uncertainties and unbounded delay is addressed. On the assumption that the interconnected functions of the studied systems satisfy the Lipschitz condition, by resorting to vector Lyapunov approach and M-matrix theory, the sufficient conditions to ensure the robust exponential stability of the switched interconnected systems under arbitrary switching are obtained. The proposed method, which neither require the individual subsystems to share a Common Lyapunov Function (CLF), nor need to involve the values of individual Lyapunov functions at each switching time, provide a new way of thinking to study the stability of arbitrary switching. In addition, the proposed criteria are explicit, and it is convenient for practical applications. Finally, two numerical examples are given to illustrate the correctness and effectiveness of the proposed theories.     

Stability analysis of cyclic switched nonlinear systems via event-triggered method

In this paper, the exponential stability problem is addressed for a class of cyclic switched nonlinear systems with unstable modes. A novel event-triggered cyclic switching scheme (ETCSS) is proposed to generate a cyclic switching signal that exponentially stabilizes the considered system for any given initial configuration. Some easily verifiable stability criteria for switched nonlinear and linear systems are established, and the effects of event parameters on the convergence rate are also analyzed. Different from the existing studies, here the developed switching scheme is not only cyclic but also event-triggered and thereby the switching frequency is relatively low. Finally, a numerical example is given to verify the efficiency of the method.     

Input-to-state stability and sliding mode control of the nonlinear singularly perturbed systems via trajectory-based small-gain theorem

This paper presents the trajectory-based input-to-state stability (ISS) and input-to-output stability (IOS) small-gain theorem, and the finite-time ISS (FTISS) and finite-time IOS (FTIOS) of nonlinear singularly perturbed systems. The contribution of this paper is threefold. Firstly, a novel idea is proposed to analyze the stability of the nonlinear singularly perturbed system, which is regarded as an interconnected system by using two-time-scale decomposition. Secondly, the trajectory-based approach is applied to establish ISS and IOS small-gain theorem for singularly perturbed systems and the FTISS and FTIOS properties are proposed. Thirdly, a novel sliding mode controller is developed for a class of nonlinear singularly perturbed systems. Finally, the effectiveness of proposed method is illustrated by using a numerical example, a DC motor simulation and a multi-agent singularly perturbed system.     

具有输入时滞的时滞关联不确定系统的鲁棒分散控制

研究了一类同时具有输入时滞以及不确定参数的时滞关联大系统的稳定性问题.基于所谓的还原法,给出一种新的状态反馈控制器的设计方法,这种方法的不同之处在于利用了时延的大小以及反馈控制的历史信息.根据Lyapunov稳定性理论得到了系统在控制器作用下稳定的充分条件,所有条件都化成可解的标准LMIs(Linear matrix inequalities)形式.文章最后给出了一个数值例子说明本文结果的可行性.