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Reliability and availability analysis of on surface transit systems
1164
World Abstracts on Microelectronics and Reliability
able to expand the system failure event in the form of unions of mutually exclusive events. Simple substitution of probabilities of success or failure, as the case may be, of the events involved in the union of expanded form gives the unreliability of the system. The algorithm is explained by an example.
Cost-effective reliable software engineering and development. ARUMALLAV. REDOI. Microelectron. Reliab. 24, 677 (1984). In recent years the development of superfast computer systems with very high speeds and throughputs is growing rapidly with the tremendous advances in computer hardware technology. At the same time the software costs are becoming more dominant in the total system costs. Considering these aspects some of the most important considerations in the development and maintenance of computer software in costeffective reliable software engineering and development are discussed. For the success of software managers, effective management and software engineering and development techniques have been presented to reduce the software lifecycle costs and to improve the efficiency of reliable software management in practice. An extensive survey of cost-effective reliable software engineering and development techniques, and the foundation upon which to establish the development and maintenance environment for future software systems are also provided. s-Expected number of inspections and repairs of a one-server two-unit system subject to arbitrary failure. R. SUBRAMANYAM NAIDU and M. N. GOPALAN. Microelectron. Reliab. 24, 647 (1984). The paper deals with a single-server two-unit system subject to random inspection and two failure modes. It is assumed that the failure time of a unit is distributed arbitrarily while all the other time distributions involved are exponential. Further, it is assumed that there is a singleservice facility which serves the dual purpose of inspection and repair. At any instant t, the system is characterized by the probabilities of its being in the "up" or "down" state. Integral equations are set up for these probabilities by adopting the regeneration point technique. A cost-benefit analysis of the system is developed by obtaining various system characteristics of importance, namely, 1. s-expected number of inspections in [0,t], 2. s-expected number of repairs of type i (i = 1, 2) in [0,t] and 3. s-expected net gain per unit time in [0, t].
Adaptive probability distribution estimation based upon maximum entropy. JAMESE. MILLER, JR., RICHARD W. KULP and GEORGE E. ORR. IEEE Trans. Reliab. R-33, 353 (1984). Our ad-hoc adaptive estimation procedure for the probability distribution of a continuous random variable is based upon the Shannon Jaynes maximum entropy concept and uses regression techniques or the Kullback-Leibler Divergence measure of information variation to select the appropriate functions for fitting a regular exponential family distribution to the data. This parametric estimation technique uses the data to select the probability distribution and estimate the parameters of the distribution. It is not known how this technique compares to other parametric techniques (eg. maximum likelihood) when the underlying distribution is known. However, this procedure is reasonable when the underlying distribution is not known. The scheme has been tested against known distributions with excellent results. A method of predicting availability characteristics of series-parallel systems. M. MODARRES.IEEE Trans. Reliab. R-33, 309 (1984). A simple method for predicting failure characteristics of a series-parallel system from the failure characteristics of the components that compose the system is presented. It is tutorial, and explained in detail.
Refiability and availability analysis of on surface transit systems. BALBIR S. DHILLON and SUBRAMANYAM N. RAYAPATl. Microelectron. Reliab. 24, 1029 (1984). This paper presents four Markov models pertaining to repairable and non-repairable on surface transit systems. The expressions for state probabilities, system reliability, mean time to failure (MTTF) and steady state availability are developed. System reliability, MTTF and steady state availability plots for various assumed values of system parameters are shown. The generic method of the muitistate fault tree analysis. HUANG XIZHI. Microelectron. Reliab. 24, 617 (1984). The FTA method suited for multistate components has already been researched [3], bat now it is apparent that it is only within the scope of the coherent system. This paper first extends it to the non-coherent system of multistate components, then further extends it to the multistate system. Theoretically speaking, the method mentioned below might be used for analysing any multistate system, no matter how complex its structure will be, and how many failure states the system and its components might take. State space representation of Petri nets. G. S. HURA. Microelectron. Reliab. 24, 865 (1984). The reachability concepts and firing characteristics of Petri nets are used to obtain a new mathematical behavioural notation of Petri nets. The proposed notation describes the binary relationships between input and output variables of the modeled system. This helps in studying the dynamic behaviour of various modules and also their interactions within the system. Catastrophic failure modes limit redundancy effectiveness. J. VON BANK. IEEE Trans. Reliab. R-32, 409 (1983). This paper shows that it is essential to know the failure rates of the failure modes in order to decide effectively about employing redundancy. In general, all redundancy decisions fall into one of two regions: (1) additional redundancy is effective, and (2) additional redundancy is not effective. This paper quantifies the boundary between these two regions. There will always be a point at which the reliability is decreased with further redundancy due to the diminishing returns caused by the catastrophic failure modes. Any design using redundant components must examine the trade-off criteria before choosing to use redundancy or the manner in which redundant components are interfaced. MIL-HDBK-217 is deficient in that the composite failure rate is not broken down into the relative failure rates of various failure modes. Approximate tolerance limits and confidence limits on reliability for the Gamma distribution. LEE J. BAIN, MAX ENGELHARDT and WEI-KEI SHIUE. IEEE Trans. Reliab. R-33, 184 (1984). No exact method is known for determining tolerance limits or s-confidence limits for reliability for the gamma distribution when both parameters are unknown. Perhaps the simplest approximate method is to determine a tolerance limit assuming the shape parameter known and then replace the shape parameter with its ML estimate to obtain approximate limits. Simulated values of the true probability levels, achieved by this method, indicate that this method is not suitable, contrary to what has been anticipated. A second approach is to consider the corresponding tolerance limits assuming the distribution mean known and the shape parameter unknown, and then replace the distribution mean by the sample mean. This approach gives useful results for many practical cases. Simulated values of the true probability levels achieved are presented for some typical cases and limiting values are provided. This method appears satisfactory for all values of the shape parameter for the common s-confidence levels, and moderate sample sizes. An empirically developed Fourier series model for describing software failures. LARRY H. CROW and NOZER D.
World Abstracts on Microelectronics and Reliability
able to expand the system failure event in the form of unions of mutually exclusive events. Simple substitution of probabilities of success or failure, as the case may be, of the events involved in the union of expanded form gives the unreliability of the system. The algorithm is explained by an example.
Cost-effective reliable software engineering and development. ARUMALLAV. REDOI. Microelectron. Reliab. 24, 677 (1984). In recent years the development of superfast computer systems with very high speeds and throughputs is growing rapidly with the tremendous advances in computer hardware technology. At the same time the software costs are becoming more dominant in the total system costs. Considering these aspects some of the most important considerations in the development and maintenance of computer software in costeffective reliable software engineering and development are discussed. For the success of software managers, effective management and software engineering and development techniques have been presented to reduce the software lifecycle costs and to improve the efficiency of reliable software management in practice. An extensive survey of cost-effective reliable software engineering and development techniques, and the foundation upon which to establish the development and maintenance environment for future software systems are also provided. s-Expected number of inspections and repairs of a one-server two-unit system subject to arbitrary failure. R. SUBRAMANYAM NAIDU and M. N. GOPALAN. Microelectron. Reliab. 24, 647 (1984). The paper deals with a single-server two-unit system subject to random inspection and two failure modes. It is assumed that the failure time of a unit is distributed arbitrarily while all the other time distributions involved are exponential. Further, it is assumed that there is a singleservice facility which serves the dual purpose of inspection and repair. At any instant t, the system is characterized by the probabilities of its being in the "up" or "down" state. Integral equations are set up for these probabilities by adopting the regeneration point technique. A cost-benefit analysis of the system is developed by obtaining various system characteristics of importance, namely, 1. s-expected number of inspections in [0,t], 2. s-expected number of repairs of type i (i = 1, 2) in [0,t] and 3. s-expected net gain per unit time in [0, t].
Adaptive probability distribution estimation based upon maximum entropy. JAMESE. MILLER, JR., RICHARD W. KULP and GEORGE E. ORR. IEEE Trans. Reliab. R-33, 353 (1984). Our ad-hoc adaptive estimation procedure for the probability distribution of a continuous random variable is based upon the Shannon Jaynes maximum entropy concept and uses regression techniques or the Kullback-Leibler Divergence measure of information variation to select the appropriate functions for fitting a regular exponential family distribution to the data. This parametric estimation technique uses the data to select the probability distribution and estimate the parameters of the distribution. It is not known how this technique compares to other parametric techniques (eg. maximum likelihood) when the underlying distribution is known. However, this procedure is reasonable when the underlying distribution is not known. The scheme has been tested against known distributions with excellent results. A method of predicting availability characteristics of series-parallel systems. M. MODARRES.IEEE Trans. Reliab. R-33, 309 (1984). A simple method for predicting failure characteristics of a series-parallel system from the failure characteristics of the components that compose the system is presented. It is tutorial, and explained in detail.
Refiability and availability analysis of on surface transit systems. BALBIR S. DHILLON and SUBRAMANYAM N. RAYAPATl. Microelectron. Reliab. 24, 1029 (1984). This paper presents four Markov models pertaining to repairable and non-repairable on surface transit systems. The expressions for state probabilities, system reliability, mean time to failure (MTTF) and steady state availability are developed. System reliability, MTTF and steady state availability plots for various assumed values of system parameters are shown. The generic method of the muitistate fault tree analysis. HUANG XIZHI. Microelectron. Reliab. 24, 617 (1984). The FTA method suited for multistate components has already been researched [3], bat now it is apparent that it is only within the scope of the coherent system. This paper first extends it to the non-coherent system of multistate components, then further extends it to the multistate system. Theoretically speaking, the method mentioned below might be used for analysing any multistate system, no matter how complex its structure will be, and how many failure states the system and its components might take. State space representation of Petri nets. G. S. HURA. Microelectron. Reliab. 24, 865 (1984). The reachability concepts and firing characteristics of Petri nets are used to obtain a new mathematical behavioural notation of Petri nets. The proposed notation describes the binary relationships between input and output variables of the modeled system. This helps in studying the dynamic behaviour of various modules and also their interactions within the system. Catastrophic failure modes limit redundancy effectiveness. J. VON BANK. IEEE Trans. Reliab. R-32, 409 (1983). This paper shows that it is essential to know the failure rates of the failure modes in order to decide effectively about employing redundancy. In general, all redundancy decisions fall into one of two regions: (1) additional redundancy is effective, and (2) additional redundancy is not effective. This paper quantifies the boundary between these two regions. There will always be a point at which the reliability is decreased with further redundancy due to the diminishing returns caused by the catastrophic failure modes. Any design using redundant components must examine the trade-off criteria before choosing to use redundancy or the manner in which redundant components are interfaced. MIL-HDBK-217 is deficient in that the composite failure rate is not broken down into the relative failure rates of various failure modes. Approximate tolerance limits and confidence limits on reliability for the Gamma distribution. LEE J. BAIN, MAX ENGELHARDT and WEI-KEI SHIUE. IEEE Trans. Reliab. R-33, 184 (1984). No exact method is known for determining tolerance limits or s-confidence limits for reliability for the gamma distribution when both parameters are unknown. Perhaps the simplest approximate method is to determine a tolerance limit assuming the shape parameter known and then replace the shape parameter with its ML estimate to obtain approximate limits. Simulated values of the true probability levels, achieved by this method, indicate that this method is not suitable, contrary to what has been anticipated. A second approach is to consider the corresponding tolerance limits assuming the distribution mean known and the shape parameter unknown, and then replace the distribution mean by the sample mean. This approach gives useful results for many practical cases. Simulated values of the true probability levels achieved are presented for some typical cases and limiting values are provided. This method appears satisfactory for all values of the shape parameter for the common s-confidence levels, and moderate sample sizes. An empirically developed Fourier series model for describing software failures. LARRY H. CROW and NOZER D.