Web站点的故障转移群集的应用

分析了故障转移群集的基本原理，运用“故障转移群集化”来规划网络，保证了Web站点的安全性和数据的可靠性，通过提供应用程序服务器中的冗余设计，来避免应用程序故障(可用性中断)，并确保联机商业活动的安全性与可靠性。     

一种基于C/S模式的分布式数据库服务器系统模型

该文介绍了一种分布式数据库服务器的构成原理及工作模型,讨论了它的冗余关系、中间件结构、并发控制策略、实现机理及其性能分析等。     

A combined approach to solve the redundancy optimization problem for multi-state systems under repair policies

This paper combines universal moment generating function technique with stochastic Petri nets to solve the redundancy optimization problem for multi-state systems under repair policies. Redundant elements are included in order to achieve a desirable level of production availability. The elements of the system are characterized by their cost, performance and availability. These elements are chosen from a list of products available on the market. The number of repair teams is less than the number of reparable elements, and a repair policy specifies the maintenance priorities between the system elements. A heuristic is proposed to determine the minimal cost system configuration under availability constraints. This heuristic, first applies universal moment generating function technique to evaluate the system availability, assuming unlimited maintenance resources. Once a preliminary solution is found by the optimization algorithm, stochastic Petri nets are used to model different repair policies, and to find the best system configuration (architecture and number of repairmen) in terms of global performance (availability and cost). This combined procedure is applied to a reference example.     

基于信号重要子空间匹配追踪的擦除补偿方法

近年来的研究表明,自然界中能够为人们所理解的信号都具有稀疏的性质。利用信号的稀疏性,提出了一种基于被擦除信号重要子空间匹配追踪的擦除补偿方法。首先,在给定错误率的基础上定义了信号稀疏性的度量方法。然后,依据被擦除信号的有效部分基于正交匹配追踪方法来寻找信号的重要子空间。最后,基于迭代方程在信号的重要子空间中获得信号的近似表示,并将其作为被擦除信号的补偿信号。模拟实验结果显示了所提出方法补偿被擦除信号的有效性。     

On the value of redundancy subject to common-cause failures: Toward the resolution of an on-going debate

Common-cause failures (CCF) are one of the more critical and challenging issues for system reliability and risk analyses. Academic interest in modeling CCF, and more broadly in modeling dependent failures, has steadily grown over the years in the number of publications as well as in the sophistication of the analytical tools used. In the past few years, several influential articles have shed doubts on the relevance of redundancy arguing that “redundancy backfires” through common-cause failures, and that the latter dominate unreliability, thus defeating the purpose of redundancy. In this work, we take issue with some of the results of these publications. In their stead, we provide a nuanced perspective on the (contingent) value of redundancy subject to common-cause failures. First, we review the incremental reliability and MTTF provided by redundancy subject to common-cause failures. Second, we introduce the concept and develop the analytics of the “redundancy–relevance boundary”: we propose this redundancy–relevance boundary as a design-aid tool that provides an answer to the following question: what level of redundancy is relevant or advantageous given a varying prevalence of common-cause failures? We investigate the conditions under which different levels of redundancy provide an incremental MTTF over that of the single component in the face of common-cause failures. Recognizing that redundancy comes at a cost, we also conduct a cost–benefit analysis of redundancy subject to common-cause failures, and demonstrate how this analysis modifies the redundancy–relevance boundary. We show how the value of redundancy is contingent on the prevalence of common-cause failures, the redundancy level considered, and the monadic cost–benefit ratio. Finally we argue that general unqualified criticism of redundancy is misguided, and efforts are better spent for example on understanding and mitigating the potential sources of common-cause failures rather than deriding the concept of redundancy in system design.     

基于稀疏重建的信号DOA估计

从稀疏信号重建角度提出了一种改进的波达方向(DOA)估计方法。由于最小冗余线阵(MRLA)能以较少的阵元数获得较大的阵列孔径,将MRLA与l1-SVD方法相结合估计信号的DOA。仿真结果表明,经多次实验验证,所提方法是有效的,相比l1-SVD方法可以估计出更多信源的DOA,并且可以用较少的阵元数估计更多的信源DOA,具有信源过载能力。     

命题逻辑公式中的冗余子句及冗余文字

主要研究命题逻辑公式中的冗余子句和冗余文字。针对子句集中必需的、有用的、无用的子句,分别给出了一些等价描述方法,进而讨论子句集的无冗余等价子集。另外,得到了子句集中冗余文字的判别方法,借助可满足性给出了冗余子句的一种等价条件。上述结果为命题逻辑公式的化简奠定了一些理论基础。     

分布式网络故障检测及恢复技术研究

IEC 62439系列协议专为高可用性工业自动化网络所设计,它们各具特点,着重分析IEC 62439-6 DRP（分布式冗余协议）的通信机理以及故障检测与恢复机制。根据DRP环形网络循环周期、网络交换设备数量、报文处理时间等一系列参数,提出了一种关于故障检测至恢复所需时间的算法。经测试平台的验证,DRP网络能迅速地检测出节点和链路的故障,并能在短时间内恢复网络的通信功能,满足现代工业网络对网络高可用性的要求。     

基于VxWorks+ARM9的PROFIBUS-DP冗余主站的设计

以ARM9微处理器与VxWorks操作系统为基础设计实现冗余PROFIBUS-DP主站控制器.详细讨论了冗余DP主站控制器对从站的管理维护以及冗余通信与主备切换的实现方法,并提供了与上位机通信的以太网接口,通过该接口可以对冗余DP主站组态并监控运行状态.本设计对国内冗余DP主站方面的研究提供了一种参考.     

FADS压力传感器冗余配置研究

嵌入式大气数据传感器系统通过在飞行器各部位的压力传感器阵进行工作,压力传感器的数量,布局形式将对系统的工作性能产生影响.为衡量冗余配置的性能,提出两项性能指标:可靠件,噪声抑制性能,并分别给出性能指标的具体计算方法.根据现有典型的压力传感器布局类型,分别计算出不同压力传感器数量、不同布局形式的性能指标.通过对性能指标的分析得出结论:可靠性,噪声抑制性能随压力传感器数量增加而增加;放射型布局的噪声抑制性能最优.