Robustness and exponentiality in redundant repairable systems

A redundant system of independent repairable components with general failure time and repair time distributions is considered. It is shown that the system failure time has an expectation dependent only on the mean failure times and mean repair times of the components and not on their distributions. An intuitive argument is provided, based on the time of onset of the quasi-stationary distribution on the set of working states, to show that for highly reliable systems, the system failure time is exponentially distributed to good approximation. The argument also justifies a simple figure of merit for the quality of the exponential approximation. A key ingredient in the analysis is the system relaxation time, an informal review of which is provided.     

Q-superlinear convergence of the iterates in primal-dual interior-point methods

Sufficient conditions are given for the Q-superlinear convergence of the iterates produced by primal-dual interior-point methods for linear complementarity problems. It is shown that those conditions are satisfied by several well known interior-point methods. In particular it is shown that the iteration sequences produced by the simplified predictor–corrector method of Gonzaga and Tapia, the simplified largest step method of Gonzaga and Bonnans, the LPF+ algorithm of Wright, the higher order methods of Wright and Zhang, Potra and Sheng, and Stoer, Wechs and Mizuno are Q-superlinearly convergent. Received: February 9, 2000 / Accepted: February 20, 2001?Published online May 3, 2001     

Quadruple systems of the projective special linear group PSL(2,q), q ≡ 1 (mod 4)

We determine the distribution of quadruple systems among the orbits of 4‐element subsets under the action of PSL(2,q) on the projective line when q ≡ 1 (mod 4). © 2003 Wiley Periodicals, Inc. J Combin Designs 11: 339–351, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/jcd.10043     

残差绝对值之和最小准则下回归方程的求法

本应用线性规划方法,解决了“残差绝对值之和最小”,“最大偏差最小”准则下回归方程的求法,这种方法对于建立多元线性回归方程、多项式回归方程和可以线性化的回归方程都是有效的。     

Non-coercive Linear Elliptic Problems

We study here some linear elliptic partial differential equations (with Dirichlet, Fourier or mixed boundary conditions), to which convection terms (first order perturbations) are added that entail the loss of the classical coercivity property. We prove the existence, uniqueness and regularity results for the solutions to these problems.     

A Polynomial Time Approximation Scheme for the Grade of Service Steiner Minimum Tree Problem

In this paper, we present the design of a Polynomial Time Approximation Scheme (PTAS) for the Grade of Service Steiner Minimum Tree (GOSST) problem, which is known to be NP-Complete. Previous research has focused on geometric analyses and different approximation algorithms have been designed. We propose a PTAS that provides a polynomial time, near-optimal solution with performance ratio 1+. The GOSST problem has some important applications. In network design, a fundamental issue for the physical construction of a network structure is the interconnection of many communication sites with the best choice of the connecting lines and the best allocation of the transmission capacities over these lines. Good solutions should provide paths with enough communication capacities between any two sites, with the least network construction costs. Also, the GOSST problem has applications in transportation, for road constructions and some potential uses in CAD in terms of interconnecting the elements on a plane to provide enough flux between any two elements.     

冗余技术提高PLC控制系统可靠性的研究

针对工业现场对PLC控制系统可靠性提出更高的要求,提出利用冗余技术提高其可靠性。分析了硬件冗余和软件冗余在PLC控制系统中的应用,详细阐述了PLC控制器、输入输出口、通讯网络和电源各自的冗余方法,并着重以西门子300/400系列PLC为例进行了软硬件冗余的架构和原理分析。最后对冗余控制系统的可靠性进行分析,结果表明,使用冗余技术可使PLC控制系统的可靠性得到明显提高。     

场景自适应的红外焦平面成像动态范围调整技术

针对红外焦平面对辐射强度较大的目标输出动态范围不足的问题,提出了一种场景自适应的红外焦平面成像动态范围调整技术。包括3个方面的内容：从图像中提取目标灰度特征,获取动态范围自适应依据;结合最小均方自适应滤波算法,对调整依据进行滤波预测后给出调节值;把灰度调节值转换成电平值,利用电平值设置红外焦平面偏置电压完成焦平面成像动态范围自适应。最后,对整体方案进行了实验验证。通过在红外焦平面成像系统中实验证明了基于场景成像动态范围自适应方法的可行性,并获得了很好的效果,成像质量有明显提高。     

求解多主多从线性斯坦伯格问题的新方法

在本文中,我们研究斯坦伯格问题,发展了罚函数法。     

On Tensor Products of l-Operators and bo-Operators

It is proved that the tensor product of two linear operators is a cone summing operator (respectively, order bounded operator) if and only if both operators are cone summing (respectively, order bounded).