IEEE Transactions on Reliability

A typographical error in the log-likelihood in the paper by N. Ebrahimi (see ibid., vol.45, p.54-8, 1996) is corrected. View full abstract»

This paper studies the steady-state availability of systems with times to outages and recoveries that are generally distributed. Availability bounds are derived for systems with limited information about the distributions. Also investigated are the applicability of convenient exponential models in evaluating availability for systems that have two-sided bounded distributions of times to planned out... View full abstract»

A component-based software development approach has become a trend in integrating modern software systems. To ensure the overall reliability of an integrated software system, its software components have to meet certain reliability requirements, subject to some testing schedule and resource constraints. Efficiency improvement of the system-testing can be formulated as a combinatorial optimization ... View full abstract»

A new approach is proposed for the data analysis of failure-censored step-stress accelerated life tests with exponential failures, following an assumed log-linear life-stress relationship. This approach, transformed least squares: (1) provides closed-form parameter estimates; (2) motivates a simple statistic for life-stress relationship verification; and (3) appreciably simplifies the derivation o... View full abstract»

This paper studies a deteriorating simple repairable system. In order to improve the availability or economize the operating costs of the system, the preventive repair is adopted before the system fails. Assume that the preventive repair of the system is as good as new, while the failure repair of the system is not, so that the successive working times form a stochastic decreasing geometric proces... View full abstract»

A predictive-maintenance structure for a gradually deteriorating single-unit system (continuous time/continuous state) is presented in this paper. The proposed decision model enables optimal inspection and replacement decision in order to balance the cost engaged by failure and unavailability on an infinite horizon. Two maintenance decision variables are considered: the preventive replacement thre... View full abstract»

Stochastic models, describing multiple availability, are analyzed for a system with periods of operation and repair that form an alternating renewal process with exponential times to failure and repair. For the simplest case multiple availability is defined as the probability that the system is available in the interval [0, t) at each moment of demand. Instants of demand form a homogeneous Poisson... View full abstract»

This paper proposes a generalized phased-mission system (GPMS) analysis methodology called GPMS-CPR that has high computation efficiency and is easy to implement. GPMS-CPR can evaluate a wider range of more practical systems with less restrictive mission requirements, while offering more human-friendly performance indices such as multilevel grading as compared to the previous PMS approaches. GPMS-... View full abstract»

The "explosive growth in bursty traffic" changes the network dynamics and requires a good evaluation of various classes of service when designing an access network. From a topological standpoint, the multiservice networks in this paper are heterogeneous systems which integrate both a core and some wireless access networks into an infrastructure similar to third-generation wireless networks. Such n... View full abstract»

During the early stages of conceptual design, the ability to predict reliability is very limited. Without a prototype to test in a lab environment or without field data, component failure rates and system reliability performance are usually unknown. A popular method for early reliability prediction is to develop a computer model for the system. However, most of these models are extremely specific ... View full abstract»

Optimal times of changing stress-level for the simple step-stress plans under the Khamis-Higgins model (an alternative to the Weibull step-stress model) are determined for a wide range of values of the model parameters. The applicability of the "optimal time of changing stress" formula obtained by Khamis-Higgins for a known shape parameter to the case of unknown shape parameter is examined. Their ... View full abstract»

Safety systems and protection systems can experience two phases of operation (standby and active); an accurate dependability analysis must combine an analysis of both phases. The standby mode can last for a long time, during which the safety system is periodically tested and maintained. Once a demand occurs, the safety system must operate successfully for the length of demand. The failure characte... View full abstract»

This paper describes a novel approach to software-implemented fault tolerance for distributed applications. This new approach can be used to enhance the flexibility and maintainability of the target applications in a cost-effective way. This is reached through a framework-approach including: (1) a library of fault tolerance functions; (2) a middleware application coordinating these functions; and ... View full abstract»

Various models have been proposed over the years to fit crack growth data. Many papers have appeared in which one or more models are mooted and fitted, and various assessments made of the quality of the fit. At the basic level the data are plotted, together with the fitted curve, to show agreement of experimental and predicted values. In this paper we suggest that it can be useful and informative ... View full abstract»

Testing has typically been a key means of detecting anomalous performance and of providing a foundation for estimating reliability for weapon systems. The objective of model-based reliability analysis (MBRA) is to identify ways to capitalize on the insights gained from physical-response modeling both to supplement the information obtained from testing and to better-understand test results. Five ge... View full abstract»

This paper describes a simple technique for estimating the mean time between failure (MTBF) of a system that has periodic maintenance at regular intervals. This type of maintenance is typically found in high reliability, mission-oriented applications where it is convenient to perform maintenance after the completion of the mission. This approximation technique can greatly simplify the MTBF analysi... View full abstract»