陶瓷刀具模糊可靠性及其与刀具材料力学性能的关系

基于模糊数学和可靠性数学的基本理论 ,阐述了刀具模糊可靠性的基本概念和评价方法 ,并进一步应用于陶瓷刀具研究领域 ,建立了陶瓷刀具模糊可靠性与刀具材料力学性能的关系 ,从而使得不做或少做切削实验就能评价陶瓷刀具可靠性的设想成为可能     

设备远程监控及故障诊断系统

基于GPRS技术和规则引擎,设计开发了一个高校仪器设备远程监控及故障诊断系统。该系统可扩展性强,能实现事件记录、远程监控、故障自诊断等功能。能够真正意义上实现对设备从采购到报废整个生命周期的管理,提高教育投资效益,减少仪器设备重复购置,降低故障率。本文从系统的组成框架、实现流程、关键功能模块以及应用实例等几个方面来介绍该系统设计思想及实现技术。该系统具有人机界面良好,实用性强,成本投资少等特点。     

Failure mode and effects analysis using a group-based evidential reasoning approach

Failure mode and effects analysis (FMEA) is a methodology to evaluate a system, design, process or service for possible ways in which failures (problems, errors, risks and concerns) can occur. It is a group decision function and cannot be done on an individual basis. The FMEA team often demonstrates different opinions and knowledge from one team member to another and produces different types of assessment information such as complete and incomplete, precise and imprecise and known and unknown because of its cross-functional and multidisciplinary nature. These different types of information are very difficult to incorporate into the FMEA by the traditional risk priority number (RPN) model and fuzzy rule-based approximate reasoning methodologies. In this paper we present an FMEA using the evidential reasoning (ER) approach, a newly developed methodology for multiple attribute decision analysis. The proposed FMEA is then illustrated with an application to a fishing vessel. As is illustrated by the numerical example, the proposed FMEA can well capture FMEA team members’ diversity opinions and prioritize failure modes under different types of uncertainties.     

结合OWA算子和模糊DEMATEL的风险评估方法

针对传统故障模式与影响分析(FMEA)方法在实际应用中的不足,提出一种基于有序加权平均(OWA)算子和决策试行与评价实验法(DEMATEL)的风险排序方法。FMEA专家对故障模式的3个风险因子给出模糊评价信息,应用OWA算子对评估信息进行集结,得到各故障原因对故障模式的影响强度。采用模糊DEMATEL法构建FMEA系统要素间的初始直接影响矩阵,经过运算可得综合影响矩阵,并计算各故障原因的原因度,据此进行产品或系统的失效风险评估。运用该方法对地铁车门系统的基础部件进行安全性分析,并将所得结果与传统RPN方法的结果做对比,验证了该方法的可行性和有效性。     

A fuzzy reasoning and fuzzy-analytical hierarchy process based approach to the process of railway risk information: A railway risk management system

Risk management is becoming increasingly important for railway companies in order to safeguard their passengers and employees while improving safety and reducing maintenance costs. However, in many circumstances, the application of probabilistic risk analysis tools may not give satisfactory results because the risk data are incomplete or there is a high level of uncertainty involved in the risk data. This article presents the development of a risk management system for railway risk analysis using fuzzy reasoning approach and fuzzy analytical hierarchy decision making process. In the system, fuzzy reasoning approach (FRA) is employed to estimate the risk level of each hazardous event in terms of failure frequency, consequence severity and consequence probability. This allows imprecision or approximate information in the risk analysis process. Fuzzy analytical hierarchy process (fuzzy-AHP) technique is then incorporated into the risk model to use its advantage in determining the relative importance of the risk contributions so that the risk assessment can be progressed from hazardous event level to hazard group level and finally to railway system level. This risk assessment system can evaluate both qualitative and quantitative risk data and information associated with a railway system effectively and efficiently, which will provide railway risk analysts, managers and engineers with a method and tool to improve their safety management of railway systems and set safety standards. A case study on risk assessment of shunting at Hammersmith depot is used to illustrate the application of the proposed risk assessment system.     

505E调速器在U-GB151CO2压缩机上的应用

川化股份有限公司化肥厂二化尿素装置为日产2460T尿素的大型化肥装置,其CO2压缩机采用日本三菱3V-7B型两缸四段压缩机,由抽汽注汽冷凝式透平驱动.该透平的转速控制由505E控制器实现,并与ProTech 203相结合实现压缩机的两级超速保护.Woodward 505E数字控制器适用于具有一次可调整的纯抽汽、抽补结合或纯补汽型式透平的控制,可现场编程组态,使标准的设计能适用于各种不同的控制场合.文中介绍了505E控制器在UGB151 CO2压缩机上的调速应用,并例举调速系统出现的故障,进行分析排除.     

Failure detection and consensus in the crash-recovery model

Summary. We study the problems of failure detection and consensus in asynchronous systems in which processes may crash and recover, and links may lose messages. We first propose new failure detectors that are particularly suitable to the crash-recovery model. We next determine under what conditions stable storage is necessary to solve consensus in this model. Using the new failure detectors, we give two consensus algorithms that match these conditions: one requires stable storage and the other does not. Both algorithms tolerate link failures and are particularly efficient in the runs that are most likely in practice – those with no failures or failure detector mistakes. In such runs, consensus is achieved within time and with 4 n messages, where is the maximum message delay and n is the number of processes in the system. Received: May 1998 / Accepted: November 1999     

可信度理论与测试

软件的可靠性估计、程序结构及测试之间存在着重要的联合,针对一个程序及其输入值有限集,可以由测试来处理所精心定义的程序状态。但是,程序测试的基本理论仍不明了,其部分原因是测试的目标不明确,对测试或者测试方法的评价也没有统一的标准,测试不应该以纠错为最终目标,其最终目标应该是精度量被估测软件的可靠性。其于这个目标,需要提出蝗可信度理论,并以它为基础,明确应该使用什么样的测试方法及测试环境。目前可信度理     

The election problem in asynchronous distributed systems with bounded faulty processes

Determining the “weakest” failure detectors is a central topic in solving many agreement problems such as Consensus, Non-Blocking Atomic Commit and Election in asynchronous distributed systems. So far, this has been studied extensively for several such fundamental problems. It is stated that Perfect Failure Detector P is the weakest failure detector to solve the Election problem with any number of faulty processes. In this paper, we introduce Modal failure detector M and show that to solve Election, M is the weakest failure detector to solve election when the number of faulty processes is less than ⌈n/2⌉. We also show that it is strictly weaker than P.

一种基于失效检测器的快速异步系统共识算法*

异步系统下的共识问题是容错方向中的关键问题。首先分析了几种基于失效检测器的共识算法,然后考虑减少响应时间,对现有算法提出改进。改进后的算法满足异步系统下共识问题的两阶段最低限度,并且在特定条件下可以在第一阶段快速作出响应。经实验证明,改进后的算法具有更快的响应时间和较少的通信量。