Robust Admissibility and Stabilization of Uncertain Singular Fractional-Order Linear Time-Invariant Systems

This paper addresses the robust admissibility problem in singular fractional-order continuous time systems. It is based on new admissibility conditions of singular fractional-order systems expressed in a set of strict linear matrix inequalities (LMIs). Then, a static output feedback controller is designed for the uncertain closed-loop system to be admissible. Numerical examples are given to illustrate the proposed methods.      

“分数阶广义系统容许性的充分必要条件”一文评论

《自动化学报》39卷12期的"分数阶奇异系统容许性的充分必要条件"得到了基于线性矩阵不等式的分数阶广义系统容许性充分必要条件.本文给出一个数值反例表明文献[1]中定理1的充分条件结论并不成立, 必要条件也不准确.最后, 给出了修改正确的分数阶广义系统容许性充分必要条件.相比于文献[1]的定理1, 改进后充要条件没有保守性并去除了原文中分数阶广义系统正则性的限制要求.     

平衡损失下回归系数的线性可容许性

在平衡损失函数下研究线性模型中回归系数的线性容许估计,得到了回归系数的估计在平衡损失下为可容许估计的充分必要条件.     

Changes in the standards for admitting expert evidence in federal civil cases since the Daubert decision.

The authors used a sample of federal district court opinions between 1980 and 1999 to examine how judges, plaintiffs, and defendants responded to the Supreme Court's 1993 Daubert v. Merrell Dow Pharmaceuticals, Inc. decision. They found that after Daubert (a) judges were more likely to evaluate the reliability of expert evidence, (b) the standards for admitting expert evidence tightened, and (c) the parties proposing and challenging evidence responded to the change in standards. The authors also examined how "general acceptance" of proposed evidence in the specific expert community enters the reliability assessment and which types of evidence were most affected by Daubert. Even though judges are more actively screening expert evidence, whether they are doing so in ways that produce better outcomes has not been determined. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

圆弧钢拱破坏荷载的理论计算

拱结构经常在桥梁、屋顶等大跨结构中使用。尽管这些结构构件容易出现各种失稳现象,但其中短粗拱或细长拱的侧向水平连接失效是由塑性破坏而非平面内或平面外屈曲引起的。通过极限荷载方法分析塑性破坏荷载,以最大限度地发挥截面的塑性能力和出现塑性铰后的内力重分布能力。描述了竖向荷载下圆弧钢拱塑性破坏荷载的计算方法。使用塑性力学中的上限法、下限法和位移协调法来计算塑性破坏荷载,压力致使拱截面的容许塑性力矩减小。确定外荷载与容许塑性力矩之间的非线性关系后,使用迭代法得到塑性破坏荷载。利用有限元方法对分析结果进行检验,二者的分析结果相吻合。最后基于迭代法绘制设计图。     

Admissible Observation Operators for the Right-Shift Semigroup

We give a characterization of infinite-time admissible observation operators for the right-shift semigroup on L ²[0,∞). Our main result is that if A is the generator of this semigroup and C is the observation operator, mapping D(A) into the complex numbers, then C is infinite-time admissible if and only if for all s in the open right half-plane. We derive this using Fefferman's theorem on bounded mean oscillation and Hankel operators. This result solves a special case of a more general conjecture which says that the same equivalence is true for any strongly continuous semigroup acting on a Hilbert space. For normal semigroups the conjecture is known to be true and then it is equivalent to the Carleson measure theorem. We derive some related results and partial results concerning the case when the signals are not scalar but with values in a Hilbert space. Date received: January 15, 1999. Date revised: September 24, 1999.     

An Expert Witness.

In November, 1947, I was engaged by counsel for the defense to do a psychological study of his client, an 18-year-old female who was charged with the murder of her 11-year-old brother (the State of New Jersey vs. Pearl Silverman). Following this study, I was subpoenaed to testify at a pre-trial sanity hearing. Immediately after my outlining of my qualifications to the court, the prosecution attorney attempted to disqualify me from serving as an expert witness on the grounds that I was not a practicing physician. At this point, the judge (Judge John Drewen of the Hudson County Court of Common Pleas) asked me to repeat my qualifications and, upon my so doing, he stated: "It seems to me that a psychologist is qualified to offer expert opinion in this court." (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Admissibility analysis of linear singular systems via a delta operator method

In this paper, the problem of admissibility analysis is investigated for linear singular systems through a delta operator method. The delta operator model of a linear singular continuous system is set up first for a special case and then generalised to the common case. It is shown that when the sampling period tends to zero, the delta operator model tends to the corresponding singular continuous system. In order to obtain the above delta operator model, we adopt a linear singular discrete model which contains the sampling period instead of the standard discrete one which contains no sampling period in the modeling process. The relation between the admissibility of the two singular discrete models is analysed and it is proved that the admissibility of one singular discrete model is equivalent to that of the other discrete model. Moreover, based on the relation between the discrete and delta operator models, some admissibility conditions are derived for linear singular delta operator systems. A numerical example is also provided to demonstrate the theoretical results in this paper.     

线性广义系统基于观测器的严格耗散控制

研究线性广义系统基于观测器的严格耗散控制器的设计问题。首先利用Lyapunov函数的方法,由矩阵不等式的形式给出满足要求的基于观测器的控制器存在的一个充分条件,保证闭环广义系统容许（即正则、稳定、无脉冲）且严格耗散。进而在上述条件的基础上,通过矩阵缩放技术和矩阵等价变换得到由线性矩阵不等式（LMI）形式给出的满足要求的控制器的存在条件和设计方法。最后给出一个数值算例说明设计方法的有效性及可行性。     

Pareto分布参数的Bayes估计

文章主要研究了Pareto分布的参数估计。在平方损失函数下给出了Pareto分布参数的Bayes估计,并且证明了这一估计是可容许的。在Q-对称熵损失函数下,讨论了Pareto分布参数的Bayes估计。