判定P_n(Γ)的Hilbert基的一个充要

设Γ是一作用在R^n上的紧李群，P_n(Γ)是Γ不变的多项式芽构成的环. Hilbert-Weyl定理证明了对于P_n(Γ)总存在一组由Γ不变的齐次多项式芽组成的Hilbert基. 然而，如何从Γ不变的齐次多项式芽中选出一组Hilbert基？如何判定Γ不变的齐次多项式芽的一个有限集就是P_n(Γ)的一组Hilbert基？该文借助于Noether环和不变积分的某些基本性质以及奇点理论的有关定理，证明了判定P_n(Γ)的Hilbert基的一个充要条件. 这对某些P_n(Γ)提供了计算一组Hilbert基的新途径.     

拟多项式的迭代

讨论了更广泛的拟多项式映射,研究了拟多项式的迭代,证明了关于逃逸集,充满 Julia集和Julia集的几个定理.推广了多项式动力系统的相关结果.     

有理单变元表示在优化问题上的应用

利用零维多项式系统的有理单变元表示,给出了求多项式在有限点集上的正性判定算法.同时,结合不等式证明,呈现了目标函数在零维系统约束下最优化的一个纯代数算法,从而将多元函数约束优化问题转化为单变元函数在单变元多项式约束下的优化问题.新算法不仅能处理目标函数为多项式的最优化问题,而且还能处理目标函数为有理分式函数和根式函数的的最优化问题,并且给出了目标函数最优值的精确区间表示,使得能任意精度地逼近最优值.     

P_n(Γ)一组Hilbert基的判定和计算

设Γ是一作用在Rn上的紧李群,Pn(Γ)是Γ不变的多项式芽环,Hilbert-Weyl定理证明了对于Pn(Γ)总存在一组由Γ不变的齐次多项式芽构成的Hilbert基.然而,如何从Γ不变的齐次多项式芽中选出一组Hilbert基?如何判定Γ不变的齐次多项式芽的一个有限集就是Pn(Γ)的一组Hilbert基?在有关的文献中,Pn(Γ)的一组Hilbert基常常是通过幂级数展开进行计算.作为一个补充,本文借助Noether环、不变积分的基本性质以及奇点理论的某些定理,证明了判定、计算Pn(Γ)的Hilbert基的有关定理和原理,这提供了计算某些Pn(Γ)一组Hilbert基的而与幂级数展开不同的方法.最后,举例加以说明.     

关于多项式与多项式函数相等的注记

给出了域上两个多项式作为多项式相等与作为多项式函数恒等的充要条件,引入有限域上约化多项式的概念,给出了有限域上多项式函数重根的定义及判定法则.     

P_n(Γ)一组Hilbert基的判定和计算

设Γ是一作用在Rn上的紧李群,Pn(Γ)是Γ不变的多项式芽环,Hilbert-Weyl定理证明了对于Pn(Γ)总存在一组由Γ不变的齐次多项式芽构成的Hilbert基.然而,如何从Γ不变的齐次多项式芽中选出一组Hilbert基?如何判定Γ不变的齐次多项式芽的一个有限集就是Pn(Γ)的一组Hilbert基?在有关的文献中,Pn(Γ)的一组Hilbert基常常是通过幂级数展开进行计算.作为一个补充,本文借助Noether环、不变积分的基本性质以及奇点理论的某些定理,证明了判定、计算Pn(Γ)的Hilbert基的有关定理和原理,这提供了计算某些Pn(Γ)一组Hilbert基的而与幂级数展开不同的方法.最后,举例加以说明.     

Tarski模型外的一类机器可判定问题

利用对称多项式的降维方法和证明代数不等式的胞腔分解方法,给出了一个实用的算法, 用于判定一类变元个数也是变量的多项式正性命题.这是一类在Tarski模型外的机器可判定问题.在Maple平台上,根据该算法设计的程序nprove,可以快速实现判定目标.     

关于Sturm定理的一点注记

经典的S turm定理用于判定多项式在给定区间上不同的实根个数,但是并不能刻画重根的情况.在这里定义了推广的S turm序列,将S turm定理进行一定地延拓,给出区间上多项式的所有实根均是偶重根或奇重根的充要条件.作为应用,讨论了多项式正(负)半定的判定问题.     

一类多项式系数二阶线性微分方程解法的研究

给出了一类具有多项式系数的二阶线性微分方程有多项式型特解和通解的充要条件,并在Maple下实现了这类微分方程具有多项式型特解和通解自动判定和求解的算法.     

一个新的多项式不可约判定定理

一个新的多项式不可约判定定理梅汉飞，龙占洪（湖南常德师专４１５０００）（湖南常德市五中）本文利用复数性质深化了Ｂｒｏｗ，Ｇｒａｈａ判定定理［１］，使其有更广的应用范围．约定Ｑ为有理数域，Ｚ为整数环，表示ｘ的共轭数，表示集Ａ的元素个数．表示多项式ｖ（ｘ...     

Quantized stabilization of stochastic systems with multiplicative noise under Markovian switching

A problem of quantized state feedback quadratic mean-square stabilization of discrete-time stochastic processes under Markovian switching and multiplicative noise is considered. A static quantizer is used in the feedback channel and the jump Markovian switching is modeled by a discrete-time Markov chain. The control input is simultaneously applied to both the rate vector and the diffusion term. It is shown that the coarsest quantization density that permits quadratic mean-square stabilization of this system is achieved with the use of a logarithmic quantizer, and the coarsest quantization density is determined by an algebraic Riccati equation, which is also the solution to a special linear stochastic Markovian switching control system. Also, sufficient conditions for exponential mean-square stabilization of such systems are also explored. An example is given to demonstrate the obtained results.     

Stabilization of delayed Cohen‐Grossberg BAM neural networks

This paper deals with finite‐time stabilization results of delayed Cohen‐Grossberg BAM neural networks under suitable control schemes. We propose a state‐feedback controller together with an adaptive‐feedback controller to stabilize the system of delayed Cohen‐Grossberg BAM neural networks. Stabilization conditions are derived by using Lyapunov function and some algebraic conditions. We also estimate the upper bound of settling time functional for the stabilization, which depends on the controller schemes and system parameters. Two illustrative examples and numerical simulations are given to validate the success of the derived theoretical results.     

Event-triggered control for sampled-data set stabilization of switched delayed boolean control networks

This paper considers the event-triggered control design for the uniform sampled-data set stabilization of switched delayed Boolean control networks (SDBCNs). First, using the algebraic state space representation method, SDBCNs are converted into the equivalent algebraic form. Second, using the algebraic form, the uniform sampled-data reachable sets are constructed, based on which, a necessary and sufficient condition is obtained for the uniform sampled-data set stabilization of SDBCNs. Finally, the event-triggered mechanism is presented, and a sufficient condition is proposed to design the time-variant state feedback event-triggered controller for the uniform sampled-data set stabilization of SDBCNs.     

Algebraic Multiplicities Arising from Static Feedback Control Systems of Parabolic Type

In stabilization studies of linear parabolic control systems, a successful approach is a scheme employing dynamic compensators in the feedback loop. An essential reason is the fact that both sensors and actuators cannot be designed freely, especially in the case of boundary observation/boundary feedback. Most fundamental in this scheme is a simple stabilization result under the static feedback control scheme. In this scheme, little attention has been paid to how to assign new eigenvalues of the feedback system. In this article, we show a new feature of pole assignment that shows some choices of new eigenvalues cause a deterioration of the stability property. An algebraic growth rate is added to the feedback system in such a choice.     

Chaos control and synchronization for a special generalized Lorenz canonical system – The SM system

This paper presents some simple feedback control laws to study global stabilization and global synchronization for a special chaotic system described in the generalized Lorenz canonical form (GLCF) when τ = −1 (which, for convenience, we call Shimizu–Morioka system, or simply SM system). For an arbitrarily given equilibrium point, a simple feedback controller is designed to globally, exponentially stabilize the system, and reach globally exponent synchronization for two such systems. Based on the system’s coefficients and the structure of the system, simple feedback control laws and corresponding Lyapunov functions are constructed. Because all conditions are obtained explicitly in terms of algebraic expressions, they are easy to be implemented and applied to real problems. Numerical simulation results are presented to verify the theoretical predictions.     

Finite-dimensional controller design for semilinear parabolic systems

This paper considers the stabilization of steady-state solutions of a semilinear parabolic system using finite-dimensional feedback controllers with support in an arbitrary open subset and which are active in one equation only. It is shown that such a controller, with dimension given by the largest algebraic multiplicity of the unstable eigenvalues of the linearized system, exponentially stabilizes the steady-state solution. An optimal design methodology for these types of controllers, which is based on the finite element approximation of the semilinear parabolic system, is introduced and illustrated by numerical simulation examples.     

Internal Optimal Controller Synthesis for Navier–Stokes Equations

Barbu and Triggiani (Indiana Univ. Math. J. 2004; 53:1443–1494) have proposed a solution of the internal feedback stabilization problem of Navier–Stokes equations with no-slip boundary conditions. They have shown that any unstable steady-state solution can be exponentially stabilized by a finite-dimensional feedback controller with support in an arbitrary open subset of positive measure. The finite dimension of the feedback controller is minimal and is related to the largest algebraic multiplicity of the unstable eigenvalues of the linearized equation. The feedback law is obtained as a solution of a linear-quadratic control problem. In this paper, we formulate a practical algorithm implementation of the proposed stabilization approach, based on the finite element method, and demonstrate its applicability and effectiveness using an example involving the stabilization of two-dimensional Navier–Stokes equations.     

Controllability and stabilization of periodic switched Boolean control networks with application to asynchronous updating

This paper investigates the periodic switching point controllability and stabilization of periodic switched Boolean control networks (PSBCNs), and applies the obtained results to the stabilization of deterministic asynchronous Boolean control networks (DABCNs). Firstly, using the algebraic state space representation of PSBCNs, a kind of periodic switching point controllability matrix is constructed, based on which, a necessary and sufficient condition is presented for the periodic switching point reachability and controllability of PSBCNs. Secondly, using the reachable set of PSBCNs, a constructive procedure is proposed to design time-variant state feedback controllers for the periodic switching point stabilization of PSBCNs. Finally, by converting the dynamics of DABCNs into the form of PSBCNs, the time-variant state feedback stabilization problem of DABCNs is solved.     

A stabilization algorithm of the Navier–Stokes equations based on algebraic Bernoulli equation

In this paper, we consider the stabilization of the nonstationary incompressible Navier–Stokes equations around a stationary solution by a boundary linear feedback control. The feedback operator is obtained from the solution of the algebraic Bernoulli equation associated with the penalized linearized Navier–Stokes equations around an unstable stationary solution and is used to locally stabilize the original nonlinear equations. We give the explicit factorized form of the stabilizing solution of the algebraic Bernoulli equation. The numerical effectiveness of this approach is demonstrated by stabilizing the vortex shedding behind a circular obstacle. Copyright © 2011 John Wiley & Sons, Ltd.