Stability of a nonuniform Rayleigh beam with indefinite damping

This is a continuation of our earlier work [J.M. Wang, G.Q. Xu, S.P. Yung, Exponential stability for variable coefficients Rayleigh beams under boundary feedback control: a Riesz basis approach, Systems Control Lett. 51 (1) (2004) 33–50] on the study of a nonhomogeneous Rayleigh beam and this time the stabilization is achieved via an internal damping instead of the boundary feedbacks. We continue to address a conjecture of Guo [Basis property of a Rayleigh beam with boundary stabilization, J. Optim. Theory Appl. 112(3) (2002) 529–547] in this paper and demonstrate how the damping term can affect the decay rate asymptotically. By a detailed spectral analysis, we obtain a necessary condition for the stability and establish the Riesz basis property as well as the spectrum determined growth condition for the system. Furthermore, when the damping is indefinite, we provide a condition on how “negative” the damping can be without destroying the exponential stability.     

具有边界控制的线性Timoshenko型系统的指数稳定性

本文研究多孔弹性材料在实际应用中的镇定问题.多孔物体的动力学行为由线性Timoshenko型方程描述,这样的系统一般只是渐近稳定但不指数稳定.假定系统两端都是自由的,在自由端对系统施加边界速度反馈控制,本文讨论闭环系统的适定性和指数稳定性.首先,利用有界线性算子半群理论得到了系统的适定性.进一步对系统算子的本征值的渐近值估计,得到算子谱分布在一个带域,相互分离的,模充分大的本征值都是简单本征值.通过引入一个辅助算子,利用它的谱性质以及有界线性算子的扰动理论,得到系统的广义本征向量的完整性以及Riesz基性质.最后利用Riesz基性质和谱分布得到闭环系统的指数稳定性.     

Exponential convergence and stability of delayed fuzzy cellular neural networks with time-varying coefficients

In this paper, the dynamic behaviors of fuzzy cellular neural networks (FCNNs) with time-varying coefficients and delays are considered. Some criteria are established to ensure the exponential convergence or exponential stability of such neural networks. The effectiveness of obtained results is illustrated by a numerical example.     

Exponential stability of a mono-tubular heat exchanger equation with output feedback

This paper is concerned with stability analysis of a mono-tubular heat exchanger equation with static output feedback. The mono-tubular heat exchanger equation is exponentially stable when the input variable is identically zero. In this paper, it is shown that the C₀-semigroup generated by the closed-loop operator consisting of the mono-tubular heat exchanger equation and the output feedback law satisfies the spectrum determined growth assumption.     

串联弦系统的控制器和补偿器的设计及其Riesz基

针对一类串联弦系统,在两端自由,内部连接点处力连续而位移不连续的条件下,论文先在内部连接点处构造补偿器对位移进行补偿,然后在两端设计控制器对系统进行控制.于是得到一个闭环控制系统.利用半群理论证明了这一系统的适定性.通过算子的谱分析,推出了该系统的谱由重数有限的孤立本征值构成并且谱分布在左半复平面,平行于虚轴的一个带域内.因此该系统存在Riesz基,满足谱确定增长条件并且是渐近稳定的.     

Stabilisation of Schrödinger equation in dynamic boundary feedback with a memory-typed heat equation

In this work, we study the dynamic behaviour for a heat equation with exponential polynomial kernel memory to be a controller for a Schrödinger system. By introducing some new variables, the time-variant system is transformed into a time-invariant one. Remarkably, the resolvent of the closed-loop system operator is not compact anymore. The residual spectrum is shown to be empty and the continuous spectrum consisting of finite isolated points are obtained. It is shown that the sequence of generalised eigenfunctions forms a Riesz basis for the Hilbert state space. This deduces the spectrum-determined growth condition for the C ₀-semigroup, and the exponential stability is then established.     

On boundary feedback stabilization of Timoshenko beam with rotor inertia at the tip

The feedback stabilization problem of a nonuniform Timoshenko beam system with rotor inertia at the tip of the beam is studied. First, as a special kind of linear boundary force feedback and moment control is applied to the beam‘ s tip, the strict mathematical treatment, a suitable state Hilbert space is chosen, and the well-poseness of the corresponding closed loop system is proved by using the semigroup theory of bounded linear operators. Then the energy corresponding to the closed loop system is shown to be exponentially stable. Finally, in the special case of umform beam, some sufficient and necessary conditions for the corresponding closed loop system to be asymptotically stable are derived.     

Exponential stability of a network of serially connected Euler–Bernoulli beams

The aim is to prove the exponential stability of a system modelling the vibrations of a network of N Euler–Bernoulli beams serially connected. Using a result given by K. Ammari and M. Tucsnak, the problem is reduced to the estimate of a transfer function and the obtention of an observability inequality. The solution is then expressed in terms of Fourier series so that one of the sufficient conditions for both the estimate of the transfer function and the observability inequality is that the distance between two consecutive large eigenvalues of the spatial operator involved in this evolution problem is superior to a minimal fixed value. This property called spectral gap holds. It is proved using the exterior matrix method due to W. H. Paulsen. Two more asymptotic estimates involving the eigenfunctions are required. They are established using an adequate basis.     

Exponential stabilisation of a simple tree-shaped network of Timoshenko beams system

The stabilisation problem of a forked triple system of Timoshenko beams, which is a simple tree-shaped network, is considered in this article. Suppose that the root of the fork is clamped. At the interior node of the fork, the displacement and rotational angle of the beams are continuous; the shearing force and bending moments of the beams satisfy the transmission conditions. The feedback controllers are designed at the exterior tips to stabilise this system. Then the closed-loop system is proved to be well-posed. By the eigenfrequency analysis together with the asymptotic technique, the system is shown to satisfy the spectrum-determined-growth condition. Finally, this closed-loop system is proved to be exponentially stable. Furthermore, a simulation is given to support these results.     

Exponential stability of a class of nonlinear dynamical systems with uncertainties

Exponential stability for a class of nonlinear dynamical systems with uncertainties is investigated. Based on the stability of the nominal systems, a new approach to synthesizing a class of continuous state feedback controllers for uncertain nonlinear dynamical systems is proposed. By such a class of feedback controllers, we can guarantee exponential stability of uncertain nonlinear dynamical systems. Our approach can give a clear insight into system analysis. Finally, an illustrative example is given to demonstrate the utilization of the approach developed in this paper.     

Robustness of the exponential stability of a non-linear controlled system under some state and control perturbations

Given a deterministic controlled system (in continuous time or in discrete time), we assume that we have computed a feedback control which stabilizes the system. We show that the system remains exponentially stable under some stochastic perturbations of the applied control and of the system equation.     

Output feedback stabilisation of a tree-shaped network of vibrating strings with non-collocated observation

In this article, the authors consider the simple tree-shaped network of strings with non-collocated observation. Suppose that the network consists of three strings and the displacements of these strings are continuous at the common vertex. The sensors and actuators are required to be set at different vertices. We propose an observer-based output feedback controller to stabilise this network. The exponential stability of the closed-loop network is obtained based on the Riesz basis approach together with estimates of the spectral distribution. Finally, a numerical simulation is given to support these results.     

铰支柔性梁主参数共振的时滞反馈控制

研究了时滞反馈控制作用下铰支柔性梁主参数共振问题.采用多尺度法,从理论上推导了时滞位移反馈控制作用下铰支柔性梁非线性主参数共振,分析了时滞、反馈控制增益,非线性系数等系统参数对系统非线性主参数振动的影响,分析了主参数动力响应随参数变化的规律.结果表明:随着反馈增益的增大,系统响应幅值得到明显抑制,合理地控制系统参数选取可提高振动控制的效率.     

A Riccati equation approach to maximizing the stability radius of a linear system by state feedback under structured stochastic Lipschitzian perturbations

The object of this paper is to maximize the stability radius of a linear state space system by state feedback under Lipschitzian structured stochastic perturbations. The supermanl achievable stability radius is characterized via the resolution of a parametrized Riccati equation and a matrix inequality. The dependence on the parameters is investigated and the limiting behaviour is examined. An example illustrating the results is treated at the end of the paper.     

Stabilisation of Timoshenko beam system with a tip payload under the unknown boundary external disturbances

This paper is concerned with the boundary stabilisation of a Timoshenko beam with a tip payload under the boundary external disturbances. Nonlinear feedback control laws are designed to reduce the effects of the external disturbances. Since the controlled system is nonlinear, the well posedness of the nonlinear closed-loop system is investigated using the theory of nonlinear maximal monotone operators and the variational principle. In addition, we show the exponential stability of the nonlinear controlled system using the Lyapunov direct method. In the end, the numerical simulations are displayed to illustrate the effectiveness of the proposed boundary controls.     

Spatial stability of shear deformable curved beams with non-symmetric thin-walled sections. I: Stability formulation and closed-form solutions

For spatial stability analysis of shear deformable thin-walled curved beams with non-symmetric cross-sections, an improved analytical formulation is proposed. Firstly the displacement field is introduced considering the second order terms of semi-tangential rotations. Next an elastic strain energy is derived by using transformation equations of displacement parameters and stress resultants and considering shear deformation effects due to shear forces and restrained warping torsion. And then the potential energy due to initial stress resultants is consistently derived with accurate calculation of Wagner effect. In addition, closed-form solutions for in-plane and lateral-torsional buckling loads of curved beams subjected to uniform compression and pure bending are newly derived. In the companion paper, FE procedures are developed by using curved and straight beam elements with arbitrary thin-walled sections. In numerical examples, to illustrate accuracy and validity of this study, closed-form solutions for in-plane and out-of-plane buckling loads are presented and compared with those obtained from analytical solutions by other researchers.     

Adaptive control of feedback linearizable systems: a modelling error compensation approach

An adaptive output feedback controller for single input feedback linearizable systems is proposed. The output derivatives are estimated with a state high-gain observer, and the matched uncertainties are handled using a modelling error compensation method. Compared with existing adaptive methods, this approach avoids overparameterizations yielding an (n+1)-order compensator, where n is the system dimension. Semiglobal stability is proven with the aid of existing results on the stability of controlled nonlinear systems with high-gain state observation. Copyright © 1999 John Wiley & Sons, Ltd.     

On the transfer matrix of a neutral system: Characterizations of exponential stability in input—output terms

This paper investigates the stability of linear autonomous multivariable neutral systems from an input—output viewpoint. Several frequency-domain and input—output characterizations for exponential stability of neutral systems are given. We provide two examples which illustrate that the behaviour of neutral systems may be quite different from that of retarded systems. Moreover we give necessary and sufficient conditions for the transfer functions of a neutral system to belong to certain algebras of meromorphic functions introduced in this paper.     

Frequency-domain criteria of robust stability: Discrete-time and continuous-time systems,a unified approach

This paper is concerned with the stability and robust stability of linear discrete-time and continuous-time systems. The characteristic polynomials of linear systems are transformed into the general polynomials of discrete-time systems, and similarly to the hodogram of the discrete-time system, the stability and the robust stability for the general characteristic polynomials with parameter uncertainty are analysed by using the zero exclusion method, where the order of the system is not used specifically a condition for a stability.     

Spatial stability of shear deformable curved beams with non-symmetric thin-walled sections. II: F. E. solutions and parametric study

In the companion paper, an improved formulation for spatial stability analysis of shear deformable thin-walled curved beams with non-symmetric cross-sections is presented based on the displacement field considering both constant curvature effects and the second-order terms of semi-tangential rotations. Thus the elastic strain energy and the potential energy due to initial stress resultants are consistently derived. Also closed-form solutions for in-plane and lateral-torsional buckling of curved beams subjected to uniform compression and pure bending are newly derived for mono-symmetric thin-walled curved beams under simply supported and clamped end conditions. In this paper, F. E. procedures are developed by using curved and straight beam elements with non-symmetric cross-sections. Analytical and numerical solutions for spatial buckling of shear deformable thin-walled circular beams are presented and compared in order to illustrate the accuracy and the practical usefulness of this study. In addition, the extensive parametric studies are performed on spatial stability behavior of curved beams. Particularly transition and crossover phenomena of buckling mode shapes with change in curvature and length of beam on buckling for curved beams are investigated for the first time.