An algorithm is developed to obtain a simplified reliability expression for a general network. All the success paths of the network are determined; then they are modified to be mutually disjoint. The reliability expression follows directly from the disjoint paths. The algorithm is easy and computationally economical. The reliability expression involves fewer terms and arithmetic operations than any of the existing methods. This is an advantage, considering the size of the system a reliability engineer normally handles and the frequency with which the expression is used for reliability studies.
[Show abstract][Hide abstract] ABSTRACT: The maintenance of an urban transit vehicle accounts for 60-70% of total costs over its entire life cycle, so it is critical to reduce maintenance costs and extend the life times of urban transit EMUs (electric multiple units) through research. For these researches, the reliability and availability data management system was constructed through the case study of several industries in the domestic and international in the field of reliability centered maintenance system. And we created a system to manage reliability and availability data for use in urban-EMU maintenance. In this work, we identified the major functions needed to successfully develop the system. Here we report the successful development of a reliability and availability data management system for maintenance of urban transit vehicles.
". 신뢰도를 계산하는 기존의 방 법으로는 신뢰도를 등가로 유지하면서 그래프의 전 체 가지를 소거하여 신뢰도를 구하는 방법, 그래프의 전체 연결경로를 열거하여 부울(Boole)연산에 의해서 처리하는 방법 등이 있다 . 이 연구에서는 먼저 복잡한 공정을 서브시스템간의 연결구조를 RBD(Reliability Block Diagram)으로 표 현하였다. "
[Show abstract][Hide abstract] ABSTRACT: Large scale systems, the facilities for the production of power, gas and chemical, have the complex structures. Most systems require the high reliability for the improvement of process efficiency, but it is difficult to analyze the reliability of processes with complex structures. In this study, we investigated reliability path of chemical process with k-out-of-n system by reliability block diagram(RBD) and calculated the reliability of process through the failure enumeration method of reliability path. This method should help in analyzing the reliability of k-out-of-n system.
"But finding the shortest paths is not always an easy task, especially for large-scale networks. Aggarwal and Misra (1975) proposed disjoint shortest path algorithm. Later, researchers (Dotson and Gobien, 1979; Yoo and Deo, 1988; Torrieri, 1994; Li and He, 2002) improved this algorithm and found it can give exact reliability for large-scale complex networks. "
[Show abstract][Hide abstract] ABSTRACT: The stability and reliability of electrical power grids are indispensable to the continuous operation of modern cities and critical for preparedness, response, recovery and mitigation in emergence management. Because present power grids in China are often running near their critical operation points, they are especially vulnerable and sensitive to external disturbances such as hurricanes, earthquakes and terrorist attacks, which may trigger cascading failures or blackouts. This paper describes a quantitative investigation of the stability and reliability of power grids with a focus on cascading failures under external disturbances. The 118-bus (substation) power network in Hainan, China is employed as a case study to investigate the risk of cascading failure of the regional power grids. System performance and reliability of the power grids are evaluated under two hypothetical scenarios (seismic impact and intentional disturbance) that could trigger cascading failures. By identifying the most vulnerable (critical) edges and nodes, the robustness of the power network is evaluated under the triggered cascading failures. It is found that the system reliabilities could decline as much as 95% during the triggered cascading failure. This paper also explores the use of concepts from modern complex network theories such as state transition graph and characteristic length to understand the complex mechanism of cascading failures. The findings could be useful for power industries and emergency managers to evaluate the vulnerability of power systems, understand the risk of blackout induced by cascading failures, and improve the resilience of power systems to external disturbances.
International Journal of Electrical Power & Energy Systems 10/2011; 33(8):1410-1419. DOI:10.1016/j.ijepes.2011.06.021 · 3.43 Impact Factor
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