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A multicomponent two-unit cold standby system with three modes
808
World Abstracts on Microelectronics and Reliability
determine optimal maintenance policy is developed based on Howard's Policy Iteration scheme. Numerical examples are included to illustrate the results.
On standby redundant system with repair, post repair and preventive maintenance. M. I. MAHMOUD and M. A. W. MAHMOUD. Microelectron. Reliab. 23 (5), 817 (1983). A twounit standby system with repair, post repair and preventive maintenance (PM) is considered. The Laplace transform (LT) of survivor function (SF) of time to the first system failure (TFSF) and the mean are derived. Finally one theorem about the effect of (PM) is proved. Seeded bug volume for software validation. MOHAMMEDTAHIR RAMZAN. Microelectron. Reliab. 23 (5), 981 (1983). It is not always'possible to determine the number of particular items from a population if the size of the population is unknown. The common procedure is to take a sample of items then mark these items and redistribute into the population. Then another sample is taken which will contain both marked and unmarked items, from which it is possible to estimate the population size. This technique is used in various fields such as estimation of population of fish in ponds for ecological studies, or estimation of a number of certain types of molecules in a chemical solution etc. A variation of this technique is to be used here to estimate the number of bugs resident in a computer program after debugging and hence predict the reliability of that program. High-speed testing equipment essential to AMRAAM development program success. LARRY S. KLIVANS. Microwave Syst. News 78 (November 1983). By using greater complexity and concurrent activity in a missile testing system, the methods for preparing and conducting unit verification have been simplified and speeded. Facing the headaches of early failures: a state-of-the-art review of burn-in decisions. WAY K u o and YUE KUO. Proc. IEEE 71 (1 l), 1257 (November 1983). System screening during electronic equipment manufacturing offers cost-effective opportunities to remove and replace defective items. Burn-in is an important screening method used in predicting, achieving, and enhancing field reliability. Based on a simple calculation, we would expect the number of failures in the field to be a decreasing function of burn-in period. Especially, the expected number of failures drops significantly in the first part of the curve. Thus only a few hours of burn-in greatly reduces the failure rate, hence enhancing reliability. Qualitative studies on electronics burn-in have been done. It is well known that burn-in is costly. However, a comprehensive quantitative approach is lacking in the determination of optimal burn-in periods. This paper thoroughly reviews the studies of burn-in screenings applied to industrial products. Papers published in the past have been critically commented and systematically classified. This state-of-the-art review can serve as a guide in studying the burn-in problems. Modification to the reduction technique of Thomas Case for obtaining a simplified reliability expression. K. K. Govm and R. A. AGARWALA.Microelectron. Reliab. 23 (5), 793 (1983). A modification has been suggested to the reduction technique of Thomas Case, whereby it is easier to reduce less numberof-failure terms rather than more number-of-success terms. A single unit multicomponent system subject to various types of failures. L. R. GOEL, RAKESHGUPTA and PRAVEENGUPTA. Microelectron. Reliab. 23 (5), 813 (1983). This paper investigates the mathematical model of a reparable system with several possible states of operation, failure and repair. There is also an inspection facility for deciding whether on failure, the system needs minor repair or overhaul. Repair rates are arbitrary functions of the time spent. All other transition
rates are constant. Several reliability characteristics of interest to system designers as well as operations managers have been computed and results obtained earlier are verified as particular cases.
Stochastic analysis of outdoor power systems in fluctuating environment. B. S. DHILLON and J. NATESAN. Microelectron. Reliab. 23 (5), 867 (1983). This paper presents newly developed expressions for state probabilities, system reliability, system availability and mean-time-to-failure (MTTF) for three types of outdoor electric power systems working in random environment. System measure plots are shown for all these Markov models. A multicomponent two-unit cold standby system with three modes. L. R. GOEL and RAKESH GUPTA. Microelectron. Reliab. 23 (5), 799 (1983). This paper investigates a mathematical model of a two-unit cold standby redundant system with three possible states of each unit--normal, partially failed and failed. Each unit has n components, each having a constant failure rate and a repair rate, an arbitrary function of the time spent. These vary from component to component. Steady-state probabilities, steady-state pointwise availability, mean time to system failure and Laplace transforms of various transient probabilities have been obtained. Several earlier results are verified as special cases. Network Quality Tester. R. DIETSCHI, CH. GESSLER and E. STABER. Electl Commun. 58 (2), 162 (1983). The quality of a telephone service as seen by the subscriber is an important characteristic which should be checked regularly. The network quality tester has been designed to provide rapid and accurate assessments of network quality using microprocessor controlled equipment in exchanges. Maintainability and availability calculations for series, parallel and r-out-of-n configurations. K. K. GOVIL. Microelectron. Reliab. 23 (5), 785 (1983). Maintainability and availability calculations are given for the following three configurations, viz. series configuration (1-out-of-n:F), parallel configuration (1-out-of-n : G) and r-out-of-n configuration. Mean-timeto failure (MTTF), mean-time-to-repair (MTTR), and meantime-to-availability (MTTA) are also computed using basic equations. It is assumed that exponential law holds good both for failure time and repair time. Simplification of Boolean functions through petri nets. G. S. HURA. Microelectron. Reliab. 23 (3), 467 (1983). A technique exploiting the modern concepts of Petri nets for simplification of Boolean functions is proposed. The firing concept of Petri nets has been utilized to give a Petri net interpretation to certain properties of switching algebra. These Petri net interpreted properties are then used for the simplification process. Unlike the existing method, the proposed technique does not require the functions to be expressed explicitly in a canonical form. This alleviates the computational efforts. It is simple and amenable for computer programming implementation. A multi-standby multi-failure mode system with repair and replacement policy. L. R. GOEL and RAKESHGUPTA. Microelectron. Reliab. 23 (5), 809 (1983). This paper investigates the mathematical model of a system composed of (m + l ) nonidentical units--one functioning and rn standby. Each unit of the system has three possible states--normal, degraded and failed. We consider two types of repair facilities--overhaul and minor repair. The system breaks down when the (m + 1)th unit after total failure is finally rejected and no standby remains to replace it. Several reliability characteristics of interest to system designers as well as operations managers have been computed. Results obtained earlier are verified as particular cases.
World Abstracts on Microelectronics and Reliability
determine optimal maintenance policy is developed based on Howard's Policy Iteration scheme. Numerical examples are included to illustrate the results.
On standby redundant system with repair, post repair and preventive maintenance. M. I. MAHMOUD and M. A. W. MAHMOUD. Microelectron. Reliab. 23 (5), 817 (1983). A twounit standby system with repair, post repair and preventive maintenance (PM) is considered. The Laplace transform (LT) of survivor function (SF) of time to the first system failure (TFSF) and the mean are derived. Finally one theorem about the effect of (PM) is proved. Seeded bug volume for software validation. MOHAMMEDTAHIR RAMZAN. Microelectron. Reliab. 23 (5), 981 (1983). It is not always'possible to determine the number of particular items from a population if the size of the population is unknown. The common procedure is to take a sample of items then mark these items and redistribute into the population. Then another sample is taken which will contain both marked and unmarked items, from which it is possible to estimate the population size. This technique is used in various fields such as estimation of population of fish in ponds for ecological studies, or estimation of a number of certain types of molecules in a chemical solution etc. A variation of this technique is to be used here to estimate the number of bugs resident in a computer program after debugging and hence predict the reliability of that program. High-speed testing equipment essential to AMRAAM development program success. LARRY S. KLIVANS. Microwave Syst. News 78 (November 1983). By using greater complexity and concurrent activity in a missile testing system, the methods for preparing and conducting unit verification have been simplified and speeded. Facing the headaches of early failures: a state-of-the-art review of burn-in decisions. WAY K u o and YUE KUO. Proc. IEEE 71 (1 l), 1257 (November 1983). System screening during electronic equipment manufacturing offers cost-effective opportunities to remove and replace defective items. Burn-in is an important screening method used in predicting, achieving, and enhancing field reliability. Based on a simple calculation, we would expect the number of failures in the field to be a decreasing function of burn-in period. Especially, the expected number of failures drops significantly in the first part of the curve. Thus only a few hours of burn-in greatly reduces the failure rate, hence enhancing reliability. Qualitative studies on electronics burn-in have been done. It is well known that burn-in is costly. However, a comprehensive quantitative approach is lacking in the determination of optimal burn-in periods. This paper thoroughly reviews the studies of burn-in screenings applied to industrial products. Papers published in the past have been critically commented and systematically classified. This state-of-the-art review can serve as a guide in studying the burn-in problems. Modification to the reduction technique of Thomas Case for obtaining a simplified reliability expression. K. K. Govm and R. A. AGARWALA.Microelectron. Reliab. 23 (5), 793 (1983). A modification has been suggested to the reduction technique of Thomas Case, whereby it is easier to reduce less numberof-failure terms rather than more number-of-success terms. A single unit multicomponent system subject to various types of failures. L. R. GOEL, RAKESHGUPTA and PRAVEENGUPTA. Microelectron. Reliab. 23 (5), 813 (1983). This paper investigates the mathematical model of a reparable system with several possible states of operation, failure and repair. There is also an inspection facility for deciding whether on failure, the system needs minor repair or overhaul. Repair rates are arbitrary functions of the time spent. All other transition
rates are constant. Several reliability characteristics of interest to system designers as well as operations managers have been computed and results obtained earlier are verified as particular cases.
Stochastic analysis of outdoor power systems in fluctuating environment. B. S. DHILLON and J. NATESAN. Microelectron. Reliab. 23 (5), 867 (1983). This paper presents newly developed expressions for state probabilities, system reliability, system availability and mean-time-to-failure (MTTF) for three types of outdoor electric power systems working in random environment. System measure plots are shown for all these Markov models. A multicomponent two-unit cold standby system with three modes. L. R. GOEL and RAKESH GUPTA. Microelectron. Reliab. 23 (5), 799 (1983). This paper investigates a mathematical model of a two-unit cold standby redundant system with three possible states of each unit--normal, partially failed and failed. Each unit has n components, each having a constant failure rate and a repair rate, an arbitrary function of the time spent. These vary from component to component. Steady-state probabilities, steady-state pointwise availability, mean time to system failure and Laplace transforms of various transient probabilities have been obtained. Several earlier results are verified as special cases. Network Quality Tester. R. DIETSCHI, CH. GESSLER and E. STABER. Electl Commun. 58 (2), 162 (1983). The quality of a telephone service as seen by the subscriber is an important characteristic which should be checked regularly. The network quality tester has been designed to provide rapid and accurate assessments of network quality using microprocessor controlled equipment in exchanges. Maintainability and availability calculations for series, parallel and r-out-of-n configurations. K. K. GOVIL. Microelectron. Reliab. 23 (5), 785 (1983). Maintainability and availability calculations are given for the following three configurations, viz. series configuration (1-out-of-n:F), parallel configuration (1-out-of-n : G) and r-out-of-n configuration. Mean-timeto failure (MTTF), mean-time-to-repair (MTTR), and meantime-to-availability (MTTA) are also computed using basic equations. It is assumed that exponential law holds good both for failure time and repair time. Simplification of Boolean functions through petri nets. G. S. HURA. Microelectron. Reliab. 23 (3), 467 (1983). A technique exploiting the modern concepts of Petri nets for simplification of Boolean functions is proposed. The firing concept of Petri nets has been utilized to give a Petri net interpretation to certain properties of switching algebra. These Petri net interpreted properties are then used for the simplification process. Unlike the existing method, the proposed technique does not require the functions to be expressed explicitly in a canonical form. This alleviates the computational efforts. It is simple and amenable for computer programming implementation. A multi-standby multi-failure mode system with repair and replacement policy. L. R. GOEL and RAKESHGUPTA. Microelectron. Reliab. 23 (5), 809 (1983). This paper investigates the mathematical model of a system composed of (m + l ) nonidentical units--one functioning and rn standby. Each unit of the system has three possible states--normal, degraded and failed. We consider two types of repair facilities--overhaul and minor repair. The system breaks down when the (m + 1)th unit after total failure is finally rejected and no standby remains to replace it. Several reliability characteristics of interest to system designers as well as operations managers have been computed. Results obtained earlier are verified as particular cases.