不确定性参数系统振动控制闭环特征值的上、下界估计

用凸模型理论讨论参数不确定性系统的振动控制问题。把不确定系统的振动控制转化为确定性问题来处理，然后讨论不确定参数对闭环特征值的影响，提出了闭环系统特征值上、下界的计算公式。

A method for estimating upper and lower bounds of eigenvalues of closedloop systems with uncertain parameters

Weibull distribution is a three-parameter distribution that contains normal, exponential and Rayleigh distribution as special cases. It is one of the most common and widely-used distribution in reliability theory, especially in fatigue life estimation. The goal of this paper is to use the method of probability weighted moments for estimating parameters and quantiles of fatigue life distribution (i.e. Weibull distribution) and to describe our MATLAB implementation of the method of probability weighted moments from field sample data. The relationship between sample probability weighted moments and the parameters of Weibull distribution was investigated. Two examples were presented to illustrate the applicability of the method. The results obtained from probability weighted moments were compared with the actual parameters by the method of Monte-Carlo method and with the results obtained by the method of Mean Rank Fitting and the method of Correlation Coefficient. It was demonstrated that the parameters estimated by the method of probability weighted moments are accurate enough to be used in reliability analysis.