Euler-Bernoulli梁边界反馈控制系统的Riesz基生成问题

本文用基扰动的方法,证明了由速度和角速度组成的边界反馈Ｅｕｌｅｒ－Ｂｅｒｎｏｕｌｌｉ梁振动系统的广义本征元生成状态空间Ｈ的Ｒｉｅｓｚ基,从而给出了振动系统最优指数衰减率的计算公式,     

Optimal NPID Stabilization of Linear Systems

We consider the problem of finding the optimal, robust stabilization of linear systems within a family of nonlinear feedback laws. Investigation of the efficiency of full-state based and partial-state based so-called NPID feedback schemes proposed for the stabilization of systems in robotic applications has provided the motivation for our work. We prove that, for a given quadratic Lyapunov function and a given family of nonlinear feedback laws, there exist optimal piecewise linear feedbacks that make the generalized Lyapunov derivative of the closed-loop system minimal. The result provides improved stabilization over the nonlinear stabilizing feedback law proposed in Ref. 1 as demonstrated in simulations of the Sarcos Dextrous Manipulator.     

关于连接梁的最优衰减率问题

研究具有耗散结点的连接梁的最优指数衰减率问题,该系统由于能量的衰减而导致弯矩在结点处间断,我们的方法是证明系统的一组广义征元生成状态空间的Riesz基,从而证明最优指数衰减率可由系统的谱确定。     

具有边界反馈控制弱耦合梁-弦系统的稳定性

研究具有边界反馈控制的弱耦合梁-弦系统.首先在合适的假设下,应用线性算子半群理论证明了系统的适定性;进而运用线性算子半群的频域定理证明了具有边界反馈控制的弱耦合梁-弦系统的能量是一致指数衰减的.     

基于输出反馈的一类大型互联非线性系统的鲁棒全局指数稳定

研究基于输出反馈的一类新的大型互联非线性不确定系统的鲁棒全局指数稳定问题,通过构造每个子系统收敛的状态观测器,并对观测器的状态作线性变换,得到鲁棒分散输出反馈控制器.当该反馈控制律作用于该系统时,闭环系统是全局指数稳定的.     

Exponential decay domain of energy for wave equation under feedback control

1.IntroductionLetnbeaboundedopendomaininH"(n22)withsmoothboundaryr,u~u(s)betheouternormalofrat8.GivenavectorxoEE",denotem(x)=x--xo(xER"),R=sup{im(x)IIxEfi}.SetWeconsiderthefollowingwaveequstiononnwithboundaryfeedback:whereK=(m'u)k(8),L=f(m'u),with(,n...     

Energy decay for the elastic wave equation with a local time-dependent nonlinear damping

In this paper, we shall investigate the decay property of the solutions to the initial-boundary value problem for the elastic wave equation with a local time-dependent nonlinear damping. We give some decay rate of the energy when the damping term is effective only in a neighborhood of a suitable subset of the boundary. The results obtained in this paper extend, in particular, the known results for the scalar wave equation.     

Exponential decay of Timoshenko beam with locally distributed feedback

The problem of exponential stabilization of a nonuniform Timoshenkobeam with locally distributed controls is investigated. Withoutthe assumption of different wave speeds, it is shown that, undersome locally distributed controls, the vibration of the beamdecays exponentially. The proof is obtained by using a frequencymultiplier method.     

On Boundary Stability of Wave Equations with Variable Coefficients

In this paper, we consider the boundary stabilization of the wave equation with variable coefficients by Riemmannian geometry method subject to a different geometric condition which is motivated by the geometric multiplier identities. Several (multiplier) identities (inequalities) which have been built for constant wave equation by Kormornik and Zuazua are generalized to the variable coefficient case by some computational techniques in Riemmannian geometry, so that the precise estimates on the exponential decay rate are derived from those inequalitities. Also, the exponential decay for the solutions of semilinear wave equation with variable coefficients is obtained under natural growth and sign assumptions on the nonlinearity. Our method is rather general and can be adapted to other evolution systems with variable coefficients (e.g. elasticity plates) as well.     

Large time behavior of solutions to 3D compressible Navier-Stokes-Poisson system

We consider the three-dimensional compressible Navier-Stokes-Poisson system where the electric field of the internal electrostatic potential force is governed by the self-consistent Poisson equation.If the Fourier modes of the initial data are degenerate at the low frequency or the initial data decay fast at spatial infinity,we show that the density converges to its equilibrium state at the L 2-rate (1+t)(-7/4) or L ∞-rate (1+t)(-5/2),and the momentum decays at the L 2-rate (1+t)(-5/4) or L ∞-rate (1+t)(-2).These convergence rates are shown to be optimal for the compressible Navier-Stokes-Poisson system.     

Optimal time-decay rates of the Boltzmann equation

We consider the optimal time-convergence rates of the global solution to the Cauchy problem for the Boltzmann equation in R3.We show that the global solution tends to the global Maxwellian at the optimal time-decay rate(1+t)-3/4,where the macroscopic density,momentum and energy decay at the optimal rate(1+t)-3/4 and the microscopic part decays at the optimal rate(1+t)-5/4.We also show that the solution tends to the Maxwellian at the optimal time-decay rate(1+t).5/4 in the case of the macroscopic part of the initial data is zero,where the macroscopic density,momentum and energy decay at the optimal rate(1+t)-5/4 and the microscopic part decays at the optimal rate(1+t)-7/4.These convergence rates are shown to be optimal for the Boltzmann equation.     

Boundary stabilization of wave equations with variable coefficients

The aim of this paper is to obtain the exponential energy decay of the solution of the wave equation with variable coefficients under suitable linear boundary feedback. Multiplier method and Riemannian geometry method are used.     

Exponential decay of non‐linear wave equation with a viscoelastic boundary condition

We study in this paper the global existence and exponential decay of solutions of the non‐linear unidimensional wave equation with a viscoelastic boundary condition. We prove that the dissipation induced by the memory effect is strong enough to secure global estimates, which allow us to show existence of global smooth solution for small initial data. We also prove that the solution decays exponentially provided the resolvent kernel of the relaxation function, k decays exponentially. When k decays polynomially, the solution decays polynomially and with the same rate. Copyright © 2000 John Wiley & Sons, Ltd.     

Transmission problem in thermoelasticity with symmetry

In this paper we show the existence, uniqueness and regularityof the solutions to the thermoelastic transmission problem.Moreover, when the solutions are symmetrical we show that theenergy decays exponentially as time goes to infinity, no matterhow small is the size of the thermoelastic part.     

A new algorithm for finding numerical solutions of optimal feedback control

Bing Sun Department of Mathematics, Beijing Institute of Technology, Beijing 100081, People's Republic of China and School of Computational and Applied Mathematics, University of the Witwatersrand, Wits 2050, Johannesburg, South Africa Email: bzguo{at}iss.ac.cn Received on March 15, 2007; Revision received October 17, 2007. A new algorithm for finding numerical solutions of optimal feedbackcontrol based on dynamic programming is developed. The algorithmis based on two observations: (1) the value function of theoptimal control problem considered is the viscosity solutionof the associated Hamilton–Jacobi–Bellman (HJB)equation and (2) the appearance of the gradient of the valuefunction in the HJB equation is in the form of directional derivative.The algorithm proposes a discretization method for seeking optimalcontrol–trajectory pairs based on a finite-differencescheme in time through solving the HJB equation and state equation.We apply the algorithm to a simple optimal control problem,which can be solved analytically. The consistence of the numericalsolution obtained to its analytical counterpart indicates theeffectiveness of the algorithm.     

Finite-time stabilization of a class of chaotic systems via adaptive control method

This paper investigates the stabilization of three dimensional chaotic systems in a finite time by extending our previous method for chaos stabilization. Based on the finite-time stability theory, a control law is proposed to realize finite-time stabilization of three dimensional chaotic systems. In comparison with the previous methods, the controller obtained by our method is simpler than those. Moreover, the method obtained in this paper is suitable for a class of three dimensional chaotic systems. The efficiency of the control scheme is revealed by some illustrative simulations.