THE UNCERTAIN EIGENVALUES ANALYSIS OF STRUCTURES WITH UNCERTAIN PARAMETERS

This paper presents a method for estimating the upper and lower bounds of eigenvalues of structures with uncertainties. The uncertain parameters are described by the convex model. A numerical example of the frame structure is given to illustrate the efficiency of the method. This work is supported by the National Natural Science Foundation of China(No. 19872028).     

Robust Stabilization by Dynamic Combined State and Output Feedback Compensator for Nonlinear Systems with Jumps

This paper deals with the robustness of the class of nonlinear systems with Markovian jumping parameters and unknown but bounded uncertainties. Under the assumption that the Markovian jump process (disturbance) is irreducible and under complete access to the system state and its mode, we establish robust stability results in two cases: (i) under matching conditions; and (ii) under bounded uncertainties.Research of this author was supported by the Natural Sciences and Engineering Research Council of Canada under Grant OGP0036444     

Nonfragile Robust Controller for Linear Markovian Jumping Parameter Systems with Multiplicative Brownian Disturbance

This paper deals with the uncertain class of continuous-time linear systems with Markovian jumping parameters and multiplicative Brownian disturbance. A design method for a nonfragile robust controller for this class of systems is proposed when the uncertainties are of the norm-bounded type. An LMI based sufficient condition is developed. The methodology used is based mainly on the Lyapunov approach. A numerical example is presented to show the usefulness of the proposed results.     

Decentralized Output Feedback Sliding Mode Control of Nonlinear Large-Scale Systems with Uncertainties

In this paper, a class of nonlinear large-scale interconnected systems with mismatched uncertainties is considered. Based on sliding mode control ideas, a kind of decentralized robust control scheme using only output information is presented to stabilize the system. The approach allows more general uncertain interconnections than all of the associated existing work and better robustness is achieved. Compared with existing decentralized output feedback schemes, it is unnecessary to solve Lyapunov equations and the so-called strict structural condition is avoided. Also, it is not necessary that the nominal subsystem is output feedback stabilizable. Finally, a simulation example is presented to illustrate the effectiveness of the results.     

Robust D-stability analysis for linear discrete singular time-delay systems with structured and unstructured parameter uncertainties

In this paper, the robust D-stability problem (i.e. the robusteigenvalue-clustering in a specified circular region problem)of linear discrete singular time-delay systems with structured(elemental) and unstructured (norm-bounded) parameter uncertaintiesis investigated. Under the assumptions that the linear nominaldiscrete singular time-delay system is regular and impulse-free,and has all its finite eigenvalues lying inside a specifiedcircular region, a new sufficient condition is proposed to preservethe assumed properties when structured and unstructured parameteruncertainties are added into the linear nominal discrete singulartime-delay system. When all the finite eigenvalues are justrequired to locate inside the unit circle of the z-plane, theproposed criterion will become the stability robustness criterion.For the case that the linear discrete singular time-delay systemis only subject to structured parameter uncertainties, by anillustrative example, the presented sufficient condition isshown to be less conservative than the existing one reportedrecently in the literature.     

OUTPUT VERSUS INPUT CONTROLS UNDER UNCERTAINTY: THE CASE OF A FISHERY

Abstract The paper compares the management outcomes with a total allowable catch (TAC) and a total allowable effort (TAE) in a fishery under uncertainty. Using a dynamic programming model with multiple uncertainties and estimated growth, harvest, and effort functions from one of the world's largest fisheries, the relative economic and biological benefits of a TAC and TAE are compared and contrasted in a stochastic environment. This approach provides a decision and modeling framework to compare instruments and achieve desired management goals. A key finding is that neither instrument is always preferred in a world of uncertainty and that regulator's risk aversion and weighting in terms of expected net profits and biomass, and the trade‐offs in terms of expected values and variance determine instrument choice.     

Impulsive control of permanent magnet synchronous motors with parameters uncertainties

The permanent magnet synchronous motors (PMSMs) may have chaotic behaviours for the uncertain values of parameters or under certain working conditions, which threatens the secure and stable operation of motor-driven. It is important to study methods of controlling or suppressing chaos in PMSMs. In this paper, robust stabilities of PMSM with parameter uncertainties are investigated. After the uncertain matrices which represent the variable system parameters are formulated through matrix analysis, a novel asymptotical stability criterion is established. Some illustrated examples are also given to show the effectiveness of the obtained results.     

Anti-Disturbance Compensation-Based Nonlinear Control for a Class of MIMO Uncertain Nonlinear Systems

Multi-Inputs-Multi-Outputs (MIMO) systems are recognized mainly in industrial applications with both input and state couplings, and uncertainties. The essential principle to deal with such difficulties is to eliminate the input couplings, then estimate the remaining issues in real-time, followed by an elimination process from the input channels. These difficulties are resolved in this research paper, where a decentralized control scheme is suggested using an Improved Active Disturbance Rejection Control (IADRC) configuration. A theoretical analysis using a state-space eigenvalue test followed by numerical simulations on a general uncertain nonlinear highly coupled MIMO system validated the effectiveness of the proposed control scheme in controlling such MIMO systems. Time-domain comparisons with the Conventional Active Disturbance Rejection Control (CADRC)-based decentralizing control scheme are also included.     

2006年基本物理常数国际推荐值

文章给出了国际科学技术数据委员会（简称CODATA）向全世界推荐的一组2006年基本物理常数及转换因子自洽数值.这组数据代替了先前推荐的2002 CODATA基本物理常数组.从上一次平差的截止日期2002年12月31日到这一次平差的截止日期2006年12月31日,尽管只过了4年的时间,实验和理论上一系列进展使我们对这些常数的知识有了显著改善.     

中子反应总截面测量系统关联不确定度的模拟

在15 MeV电子加速器驱动的白光中子源装置上进行了铍材料的中子总反应截面测量,测量结果与已有实验数据和ENDF/VII.1数据库的评价数据基本符合。为了得到由于加速器束流波动、飞行路径测量、靶厚度测量以及获取系统死时间等引起的测量系统的关联不确定度,利用Geant4模拟软件对整个实验装置、实验过程进行了模拟,经过对模拟中使用的中子反应总截面与模拟计算得到截面的比较分析,得到了实验系统关联不确定度的估计值。在模拟中采用了局部区域增加权重的方法来降低模拟运算时间。对模拟得到的中子飞行时间谱与实验测量得到的飞行时间谱进行了比较,并且对探测器处的中子产额也进行了比较,以此来验证模拟程序的可靠性。