Impact analysis of change in component reliabilities in safety‐critical systems

A safety‐critical system or life‐critical system is a system whose failure or malfunction may result in one (or more) of the following outcomes: death or serious injury to people and loss or severe damage to equipment/property. Such systems are very common in nuclear power plants and are composed of several components, performing different functions. The criticality of these components is ranked according to the criticality of the functions they perform. Therefore, the impact of component failure on system will be different for different components. It is essential to determine the impact of failure of any component on overall system to take preventive and corrective actions. This paper proposes a technique to determine the criticality of the components for their impact on the overall system using Bayesian approach. The theoretical basis and effectiveness of the proposed technique is shown and validated on a real case study of a nuclear power plant system.     

摩托车零部件模糊可靠性设计方法的研究

简述了摩托车零部件进行模糊可靠性设计的必要性,并从模糊可靠性设计的理论基础人手,通过对应力一强度干涉理论的相关方法的分析,并考虑摩托车零部件应力及其组合的随机性和相关强度的模糊性,讨论了适合摩托车零部件的以强度为模糊量同时以应力为随机量的一种模糊可靠性设计方法．举例说明了如何确定一些相关的参数,如何将模糊事件转化为普通事件的技术。     

机械零件可靠性设计理论与方法研究

机械可靠性设计的任务就是提供实际计算的数学模型和方法,在机械产品的研发阶段预测其在规定工作条件下的工作能力或寿命．结合可靠性理论研究的历史及现状对机械可靠性设计理论进行深入分析,阐明了可靠性优化设计、可靠性灵敏度设计、可靠性稳健设计、可靠性试验、传统设计方法与可靠性设计相结合等机械零件可靠性设计理论与方法的内涵,为机械零件可靠性设计提供系统的理论和方法．     

Circuit reliability and complexity with similar constant faults in the components

The task is considered of realizing Boolean functions asymptotically the best as regards reliability by circuits with constant faults of the same type only at the outputs or only at the inputs of the gates. The complexity of the circuits made of unreliable components that are asymptotically the best on reliability is of the same order as the complexity of circuits constructed only from reliable components. __________ Translated from Izmeritel’naya Tekhnika, No. 3, pp. 12–15, March, 2006.     

任意分布参数的机械零件的可靠性稳健设计（一）：理论部分

 将可靠性优化设计理论、可靠性灵敏度技术和稳健设计方法相结合，讨论了具有任意分布参数的机械零件的可靠性稳健设计问题，提出了可靠性稳健设计的计算方法．把可靠性灵敏度融入可靠性优化设计模型之中，将可靠性稳健设计归结为满足可靠性要求的多目标优化问题．在基本随机参数的前四阶矩已知的情况下，通过计算机程序可以实现具有任意分布参数的机械零件的可靠性稳健设计，迅速准确地得到具有任意分布参数的机械零件的可靠性稳健设计信息。     

An efficient algorithm for sequential generation of failure states in a network with multi-mode components

In this work a new algorithm for the sequential generation of failure states in a network with multi-mode components is proposed. The algorithm presented in the paper transforms the state enumeration problem into a K-shortest paths problem.Taking advantage of the inherent efficiency of an algorithm for shortest paths enumeration and also of the characteristics of the reliability problem in which it will be used, an algorithm with lower complexity than the best algorithm in the literature for solving this problem, was obtained.Computational results will be presented for comparing the efficiency of both algorithms in terms of CPU time and for problems of different size.     

An analysis of the field failure of passive and active components

This paper briefly describes work that is in hand on establishing and running an organization for the collection and analysis of field failure data on passive and active components in electronic equipment. Data have now been collected from all the sources for nearly two and a half years as of June 1989 and the results obtained are presented. Analysis covers a wide range of electronic component categories.     

Toward modeling and simulation of critical national infrastructure interdependencies

Modern society's physical health depends vitally upon a number of real, interdependent, critical infrastructure networks that deliver power, petroleum, natural gas, water, and communications. Its economic health depends on a number of other infrastructure networks, some virtual and some real, that link residences, industries, commercial sectors, and transportation sectors. The continued prosperity and national security of the US depends on our ability to understand the vulnerabilities of and analyze the performance of both the individual infrastructures and the entire interconnected system of infrastructures. Only then can we respond to potential disruptions in a timely and effective manner. Collaborative efforts among Sandia, other government agencies, private industry, and academia have resulted in realistic models for many of the individual component infrastructures. In this paper, we propose an innovative modeling and analysis framework to study the entire system of physical and economic infrastructures. That framework uses the existing individual models together with system dynamics, functional models, and nonlinear optimization algorithms. We describe this framework and demonstrate its potential use to analyze, and propose a response for, a hypothetical disruption.     

Copula‐based reliability and safety analysis of safety‐critical systems with dependent failures

A safety‐critical system (SCS) is a system whose failure could result in a certain serious consequence, such as loss of life and significant damage to property or environment. Examples of SCSs abound in real‐world applications, such as medical instruments, emergency shutdown systems, and fire/gas detection systems. An SCS can assume 1 of 3 states: working, safe failure, and dangerous (or unsafe) failure. To analyze reliability and safety of SCSs accurately, we build multi‐state models of an SCS and its constituent units. The dependent relationships (nonlinear correlation) of different parts within a safety‐critical unit as well as across the units are modeled using the Copula method. Formulas computing reliability and safety indexes of a safety‐critical unit and of safety‐critical series or parallel systems are derived. Numerical examples are provided to demonstrate the application of the proposed methodology.     

Semi-Markovian reliability models for systems with testable components and general test/outage times

Semi-Markov models for systems undergoing periodic test and maintenance are developed. In particular, systems undergoing specific changes of state at predetermined instances of time and transiting to states with generally distributed sojourn times are considered. Problems addressed by the models are those concerned with optimum assessment of test intervals, and allowable outage times. Equivalent Markovian models allowing for the decomposition of a system of dimensionality N+M into two smaller problems of dimensionality N and M, respectively are developed. The general model is also specialized to systems with instantaneously testable components, unmonitored components undergoing tests (repair, maintenance) of fixed duration, and systems containing components characterized by limited allowable outage time (under test, or repair). Approximate equivalent Markov models are derived in these cases. Simple numerical examples are also presented.     

Research on reliability allocation technology for NC machine tool meta‐action

The reliability of machine tool is getting more and more attention. Reasonable reliability allocation is beneficial to improve the inherent reliability of machine tool. However, the existing reliability allocation methods for machine tool have some limitations. For example, static part is selected as the reliability allocation object of machine tool, which cannot reflect the characteristics “function realized by motion”; factors affecting reliability allocation are not considered comprehensively, weights of experts are treated as the same, and the allocation results are not optimized or the impact of time on enterprise is neglected in the optimization. To solve these problems, a new multiobjective optimization reliability allocation method for machine tool is proposed in this paper. Firstly, the latest achievements about meta‐action are given, and meta‐action is set as the reliability allocation object. Secondly, more reasonable and comprehensive factors affecting reliability allocation are extracted. Thirdly, expert weight coefficient is brought to reduce the subjective impact of expert scoring. Fourthly, time factor is brought to make the optimized allocation results more reasonable and accurate. Finally, a numerical control (NC) machine tool made in China is taken as an example, with a comparison on the reliability allocation results of current methods and proposed method. The results verify the applicability, rationality, and accuracy of the proposed method, which lays a foundation for the subsequent study on the quality characteristics of machine tool based on meta‐action.     

基于模糊设计准则的机械可靠性优化设计研究

按照应力-强度分布干涉和模糊理论,对机械模糊可靠性优化设计方法进行系统的研究,提出了剩余可靠度的概念,建立了数学模型,给出了设计实例。研究表明：仅仅以实现要求的可靠度为目标的一般模糊可靠性设计由于不能考虑其他条件对设计变量取值的约束作用,往往导致设计结果不具可行性而失去实际意义。可靠性优化设计将模糊可靠性条件与其他所有限制条件一起作为设计约束,在设计空间围成一个可行设计域,然后按照设计目标要求用一定方法寻求可行域内的最优设计点,从而保证了设计结果既具可靠性,又具可行性和最优性。     

过盈联结的可靠性分析与优化

在机械制造,特别是重型机械制造中,过盈联结具有十分显著的经济效益,但传统的计算方法不仅复杂,而且无法对过盈联结的工作可靠性给出定量的评价,因此影响了过盈配合的工作质量,妨碍了过盈配合的广泛应用,从可靠性理论和优化技术出发,对过盈联结的可靠性进行分析,并对过盈联结可靠度的优化进行研究,建立了计算模型,编制了相应的通用计算机程序,该方法和程序,不仅可以对过盈联接的可靠度进行分析,而且可以对过盈量进行优化,有效地提高配合系统的可靠度。     

Quality and 1/f noise of electronic components

Classification rules of electronic components based on their 1/f noise measurements are presented. It is proposed to classify electronic components into four groups with different quality: high, good, low, poor. The results of investigations of type BF 414 transistors are reported.     

Methodology for the optimal component selection of electronic devices under reliability and cost constraints

The objective of this paper is to present an efficient computational methodology for the reliability optimization of electronic devices under cost constraints. The system modeling for calculating the reliability indices of the electronic devices is based on Bayesian networks using the fault tree approach, in order to overcome the limitations of the series–parallel topology of the reliability block diagrams. Furthermore, the Bayesian network modeling for the reliability analysis provides greater flexibility for representing multiple failure modes and dependent failure events, and simplifies fault diagnosis and reliability allocation. The optimal selection of components is obtained using the simulated annealing algorithm, which has proved to be highly efficient in complex optimization problems where gradient‐based methods can not be applied. The reliability modeling and optimization methodology was implemented into a computer program in Matlab using a Bayesian network toolbox. The methodology was applied for the optimal selection of components for an electrical switch of power installations under reliability and cost constraints. The full enumeration of the solution space was calculated in order to demonstrate the efficiency of the proposed optimization algorithm. The results obtained are excellent since a near optimum solution was found in a small fraction of the time needed for the complete enumeration (3%). All the optimum solutions found during consecutive runs of the optimization algorithm lay in the top 0.3% of the solutions that satisfy the reliability and cost constraints. Copyright © 2007 John Wiley & Sons, Ltd.     

渐开线行星轮系参数优选及可靠性优化设计

将渐开线行星齿轮传动参数优选的结果用于可靠性优化设计中,包括按两轮滑动率相等原则分配外啮合变位系数和X1∑;按提高内啮合副轮齿接触强度并保证具有较高重合度来确定内啮合角αH;按等强度原则寻求最佳m/a值,最后对该传动进行可靠性优化设计。     

Influence of the critical velocity on deformation of launcher components

This paper is related to the dynamics of hypervelocity electromagnetic launchers. A projectile accelerating along launcher rails may cross a range of critical velocities and induce structural resonance. As a result, the rails and other components exhibit increased displacements and stress that may affect launcher performance and lead to premature launcher failure. This work is a continuation of our previous studies of the critical velocity and resulting transient resonance that was performed for a notional hypervelocity launcher [Nechitailo NV, Lewis KB. Critical velocity for rails in hypervelocity launchers. In: Proceedings of the 2005 hypervelocity impact symposium. International Journal of Impact Engineering Dec. 2006; 33: 485–495; Lewis KB, Nechitailo NV. Transient resonance in hypervelocity launchers at critical velocities [Selected papers from the 13th Electromagnetic Launch Technology (EML) Symposium, Potsdam, Germany, May 22–25, 2006]. IEEE Transactions on Magnetics Jan. 2007; 43 (No. 1, Part II): 157–162 [1,2]]. Analytical models including Bernoulli–Euler model of a beam resting on an elastic foundation and the Timoshenko and Flügge tube models as well as finite element tools helped to better understand the transient resonant regimes in launcher components and offered insight on how to alter the launching device materials and geometry to reduce the critical-velocity effects. Analysis showed that the various components of a launcher can have different critical velocities and there is a possibility of enhanced group resonance in the assemblies. The resonance in the launcher assembly can be reduced by controlling the bending stiffness of the individual components. Finite element models were used to illustrate the influence of variations in materials of launcher components on the resulting critical velocities, intensity of the group resonance, and resulting maximum displacements and stress.     

Quality and reliability information integration for design evaluation of fixture system reliability

Quality and reliability are two important factors in manufacturing‐system design. However, the analysis and optimization of manufacturing‐system reliability and product quality are normally conducted separately in practice. There is no general framework to integrate these two important factors, quantitatively analyze the interactions between them, and further study their integrated effects on the manufacturing‐system performance. In this paper, the QR‐Co‐Effect of product/part quality and manufacturing‐system component reliability is investigated in an assembly fixture system. The concept, model and analysis of QR‐Co‐Effect are addressed in this paper. Copyright © 2001 John Wiley & Sons, Ltd.     

Influence of ions on the critical behavior of a binary mixture near the consolute point

The lower critical point of stratification of a 3-methylpyridine (MP)+heavy water (D₂O) mixture in the presence of Na⁺ and CI^– ions has been studied by the Toepler shadow method. Addition of 0.3% ions lowered the critical temperature and reduced the equilibration time and the gradient of the refractive index (compressibillity). The analysis of the form of the near-critical isotherm demonstrated the ionic mixture to be described by the index = 3.05 ± 0.15. which corresponds to the classical mean-field theory. The results obtained provide evidence that even small admixtures of charged particles result in a substantial suppression of fluctuations near the critical point by the long-range Coulomb interaction.Paper presented at the Twelfth Symposium on Thermophysical Properties, June 19–24, 1994, Boulder, Colorado, U.S.A.