关于递阶控制的几个问题

本文论述了近几年关于递阶控制的几个问题.全文分四节.第一节较详细地介绍了从无限维凸规划出发提出的辅助问题原则和松弛原则,根据这两个原则形成的统一方法可以推导出若干分解-协调算法.第二节介绍了用递阶方法离线地计算线性和非线性系统的闭环控制律,并对稳态系统的在线控制问题作了较详细的介绍.第三节论述了stackelberg策略在递阶控制中的应用.第四节介绍了两种递阶系统状态估计的算法.     

嵌入式系统门级在线自修复技术研究

为保证复杂电磁环境下嵌入式系统的安全运行,提出一种通用嵌入式系统在线故障自修复模型。基于ARM处理器和商业FPGA芯片实现原型试验系统,借鉴生物系统在遭受一定损伤时能自行康复的特点,结合仿生硬件领域中的内进化试验方法,在原型系统上设计重配置执行单元的门级冗余拓扑结构和自律控制单元的演化修复算法。利用马尔可夫模型评价系统的可靠性与稳态可用度。结果表明,在随机电磁损伤事件频繁发生并导致电路功能故障时,该系统能保持较高的可用度和安全性。     

Bi-directional self-healing ring network planning

In this paper we study the network planning problem of bi-directional self-healing ring (BSHR), which is a network structure providing higher survivability when there is a failure on link or node. Given a network with nodes, links, and demand pairs, our target is to design an optimal network comprising rings, which use only the existing links to satisfy all demands. The objective is to minimize the total amount of equipment (add/drop multiplexer) on nodes, thus reducing the major cost of SHR structure. We propose two integer programming models. For larger networks, we have developed an efficient solution procedure based on its hierarchical network structure. Computational results are given to show that the solution procedure is effective in obtaining an optimal or near-optimal solution.Scope and purposeThe merging of information networking and telecommunication services has created an increasing demand for telecommunication networks of high bandwidth, aiming to exchange ever larger volumes of data in a very short time interval. The self-healing ring (SHR) is a ring network that provides redundant bandwidth in which disrupted services can be automatically restored following network failures. In this paper, we study the network planning problem of bi-directional SHR aiming to minimize the amount of equipment.     

Data Filtering Based Multi-innovation Gradient Identification Methods for Feedback Nonlinear Systems

With the development of industry information technology, many researchers pay attention to the estimation problems of feedback nonlinear systems increasingly. In this paper, a filtering based multi-innovation stochastic gradient algorithm is derived for Hammerstein equation-error autoregressive systems by using the hierarchical technique. The parameter estimates accuracy can be improved with the innovation length increasing. These algorithms are easy to implement on-line. The simulation results verify the effectiveness of the proposed algorithm.     

多代理分层的智能配电网自愈控制研究

介绍了配电网自愈的基本概念,对传统的框架体系进行了改进,并提出一种基于智能多代理分层的配电网自愈控制技术。根据配电网的功能进行了分层,将智能多代理技术与电网的运行状态相结合,根据不同的运行状态执行不同的控制策略,并充分利用多代理技术的自治性和协同性,为智能配电网自愈控制提供理论和方法上的依据。     

一种基于J2EE应用服务器的容侵自治愈方法

针对目前容忍入侵技术和软件自治愈技术的不足,在研究现有JANTM平台的基础上,提出了一种基于J2EE应用服务器的容侵自治愈模型,并在该模型下提出了一种容侵自治愈方法;和传统单一方法相比,该方法不仅解决了容忍入侵技术中存在的隐性入侵、软件老化以及容侵前提条件易遭破坏的问题,也改善了自治愈技术中未解决的外界入侵等问题;最后通过将容侵自治愈集群、JANTM集群和JBoss4.0集群进行比较测试,验证了该容侵自治愈方法可以使基于J2EE应用服务器的容侵自治愈集群有更高的可靠性和生存性。     

一般双率随机系统状态空间模型及其辨识

对于双率采样数据系统,本文使用提升技术,推导了双率系统的提升状态空间模型.对 于系统状态可测量的双率系统,利用最小二乘原理辨识提升系统模型的参数矩阵;对于状态不 可测的未知参数双率系统,利用递阶辨识原理,提出了双率系统递阶状态空间模型辨识方法,来 辨识系统的状态和参数.具体做法:基于获得的状态估计和提升系统的输入输出数据递归估计 系统参数,然后基于获得的参数估计,计算系统的状态.     

Design of reject rules for ECOC classification systems

ECOC is a widely used and successful technique, which implements a multi-class classification system by decomposing the original problem into several two-class problems. In this paper, we study the possibility to provide ECOC systems with a tailored reject option carried out through different schemes that can be grouped under two different categories: an external and an internal approach. The first one is based on the reliability of the entire system output and does not require any change in its structure. The second scheme, instead, estimates the reliability of the internal dichotomizers and implies a slight modification in the decoding stage. Experimental results on popular benchmark data sets are reported to show the behavior of the different schemes.     

Improved survivability analysis for SONET SHRs

Recently, a special type of Markov model called parametric state reward Markov model (SRMM/p) [H.C. Cankaya, V.S.S. Nair, in: IEEE Proceedings of GLOBECOM 97, vol. 1, IEEE Computer Soc. Press, Silver Spring, MD, 1997, pp. 252–256] and a set of survivability metrics comprising reliability, availability, and restorability have been proposed for the evaluation of self-healing SONET mesh networks [H.C. Cankaya, V.S.S, Nair, in: Proceedings of ISCIS 'XII, vol. 1, Bogazici University, Bogazici University Press, 1997, pp. 269–276]. The SRMM/p accommodates multiple consecutive link failures and uses topology-free approximation in order to calculate the average performance loss due to a failure. The SRMM/p is equally applicable to the analysis of self-healing SONET rings by considering a ring as a special case of a mesh topology [H.C. Cankaya, V.S.S. Nair, in: IEEE Proceedings of GLOBECOM '98, vol. 4, IEEE Computer Soc. Press, Silver Spring, MD, 1998, pp. 2276–2281]. Further, the topological uniformity and simplicity of rings allow one to include more detailed features of the network in the model so that the analysis will be more accurate. For this purpose, we propose an improved approach to the survivability analysis of self-healing SONET rings which employs a probability-tree based evaluation of the probability of various system states resulting from all possible combinations of node and link failures. The corresponding tree-construction and traversal algorithms are presented. Survivability of rings with distinctive demand patterns are studied with the improved analysis and compared experimentally. One limitation to the model is the high run-time complexity caused mainly by the disparity between transition rates amongst various states in the SRMM/p [H.C. Cankaya, V.S.S. Nair, ACM Comput. Commun. Rev. 28 (4) (1998) 268–277]. In this paper, we also present an approach to circumvent this problem by state aggregation method and compare the results in terms of run-time complexity and accuracy by conducting an experimental study.     

Approximation Capabilities of Hierarchical Fuzzy Systems

Derived from practical application in location analysis and pricing, and based on the approach of hierarchical structure analysis of continuous functions, this paper investigates the approximation capabilities of hierarchical fuzzy systems. By first introducing the concept of the natural hierarchical structure, it is proved that continuous functions with natural hierarchical structure can be naturally and effectively approximated by hierarchical fuzzy systems to overcome the curse of dimensionality in both the number of rules and parameters. Then, based on Kolmogorov's theorem, it is shown that any continuous function can be represented as a superposition of functions with the natural hierarchical structure and can then be approximated by hierarchical fuzzy systems to achieve the universal approximation property. Further, the conditions under which the hierarchical fuzzy approximation is superior to the standard fuzzy approximation in overcoming the curse of dimensionality are analyzed     

Task allocation for maximizing reliability of distributed systems: A simulated annealing approach

This paper addresses the problem of task allocation in heterogeneous distributed systems with the goal of maximizing the system reliability. It first develops an allocation model for reliability based on a cost function representing the unreliability caused by the execution of tasks on the system processors and the unreliability caused by the interprocessor communication time subject to constraints imposed by both the application and the system resources. It then presents a heuristic algorithm derived from the well-known simulated annealing (SA) technique to quickly solve the mentioned problem. The performance of the proposed algorithm is evaluated through experimental studies on a large number of randomly generated instances. Indeed, the quality of solutions are compared with those derived by using the branch-and-bound (BB) technique.     

Reliability analysis of structures using stochastic response surface method and saddlepoint approximation

Stochastic response surface method (SRSM) is a technique used for reliability analysis of complex structural systems having implicit or time consuming limit state functions. The main aspects of the SRSM are the collection of sample points, the approximation of response surface and the estimation of the probability of failure. In this paper, sample points are selected close to the most probable point of failure and the actual limit state surface (LSS). The response surface is fitted using the weighted regression technique, which allows the fitting points to be weighted based on their distance from the LSS. The cumulant generating function (CGF) of the response surface is derived analytically. The saddlepoint approximation (SPA) method is utilized to compute the probability of failure of the structural system. Finally, four numerical examples compare the proposed algorithm with the traditional quadratic polynomial SRSM, Kriging based SRSM and direct MCS.     

Hierarchical time-extended Petri nets (H-EPNs) based erroridentification and recovery for multilevel systems

In this paper, hierarchical time-extended Petri nets (H-EPNs), an extended Petri net based modeling and analysis tool, are used to derive the coordination level model of hierarchically decomposable systems, viewed from a three-level hierarchical structure of organization, coordination and execution of tasks. A two-layer (vertical) coordination level framework, consisting of the dispatcher/analyzer and the H-EPN controller is presented. A detailed two sub-level (horizontal) H-EPN controller model is derived to model system operations (including system soft failures). Error classification based on the interaction between the various system coordinators is derived from the H-EPN model. The H-EPN approach preserves multi-resolutional system details as well as effective communication flows between the various subsystems. A simple example illustrates the proposed approach. The important H-EPN properties of boundedness, safeness and reversibility are verified.     

A tutorial on Reed–Solomon coding for fault-tolerance in RAID-like systems

It is well-known that Reed-Solomon codes may be used to provide error correction for multiple failures in RAID-like systems. The coding technique itself, however, is not as well-known. To the coding theorist, this technique is a straightforward extension to a basic coding paradigm and needs no special mention. However, to the systems programmer with no training in coding theory, the technique may be a mystery. Currently, there are no references that describe how to perform this coding that do not assume that the reader is already well-versed in algebra and coding theory. This paper is intended for the systems programmer. It presents a complete specification of the coding algorithm plus details on how it may be implemented. This specification assumes no prior knowledge of algebra or coding theory. The goal of this paper is for a systems programmer to be able to implement Reed-Solomon coding for reliability in RAID-like systems without needing to consult any external references. © 1997 John Wiley & Sons, Ltd.     

Hierarchical Fuzzy Systems for Function Approximation on Discrete Input Spaces With Application

This paper investigates the capabilities of hierarchical fuzzy systems to approximate functions on discrete input spaces. First, it is shown that any function on a discrete space has an arbitrary separable hierarchical structure and can be naturally approximated by hierarchical fuzzy systems. As a by-product of this result, a discrete version of Kolmogorov's theorem is obtained; second, it is proven that any function on a discrete space can be approximated to any degree of accuracy by hierarchical fuzzy systems with any desired separable hierarchical structure. That is, functions on discrete spaces can be approximated more simply and flexibly than those on continuous spaces; third, a hierarchical fuzzy system identification method is proposed in which human knowledge and numerical data are combined for system construction and identification. Finally, the proposed method is applied to the market condition performance modeling problem in site selection decision support and shows the better performance in both accuracy and interpretability than the regression and neural network approaches. In additions, the reason and mechanism why hierarchical fuzzy systems outperform regression and neural networks in this type of application are analyzed.      

Reliability model for hierarchical systems: Regenerative approach

Most of real technical systems and biological objects with sufficiently high organization are complex hierarchical partially controllable systems. In the paper for modeling and analysis of reliability of such systems the method of decomposable semi-regenerative processes is used. A simple example illustrates our approach.     

基于增强型双向散列链的自愈组密钥分发方案

针对基于传统双向散列链的自愈组密钥分发方法无法抵制合谋攻击的不足,提出了引入滑动窗口和轻量级子链LiBHC结构的增强型双向散列链结构,并给出了基于该结构的自愈组密钥分发方案。该方案有效地解决了组密钥的无缝切换问题,更大程度地减少了合谋攻击对系统构成的安全威胁。分析表明,本方案在保持较好的资源开销优势的前提下,获得了更好的安全性和可靠性,更适用于节点俘获攻击多发的应用场景。     

Stabilisation analysis for switched neutral systems based on sampled-data control

In this paper, the problem of stabilisation analysis for switched neutral systems based on sampled-data control and average dwell time approach is investigated. Delay-dependent stabilisation results are derived in terms of linear matrix inequalities by constructing piecewise Lyapunov–Krasovskii functional based on the Wirtinger's inequality. Also, the controller gain matrix is designed by applying an input-delay approach. Further convex combination technique and some integral inequalities are used to derive less conservative results. The effectiveness of the derived results is validated through numerical examples.     

自愈控制系统研究的综述、分析与展望

近年来,为了改变依靠紧急停车、人工维护和故障排除的传统的维修方法,在一些技术应用领域中人们提出了自愈控制的思想.本文通过梳理智能电网的自愈控制、飞行控制系统的自愈控制和机器故障自愈调控的相关研究成果,明确了自愈控制的特征和功能并给出了其定义;其次,讨论了自愈控制、自愈系统和容错控制的联系与区别;最后,总结了研究自愈控制的意义并分析了其发展趋势.作者对自愈控制的相关技术应用领域及成果进行综述和深入分析,旨在提高自愈控制系统的规范化和重用性、提炼和总结其共性并给出自愈控制系统的基本架构,从而为其将来的理论研究奠定初步的基础、为指导实际的自愈控制的应用提供一定的参考.