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A note on heuristic methods in optimal system reliability
414
World Abstracts on Microelectronics and Reliability
Optimal allocation of fault detectors. I. TAKAMI,T. INAGAKI, E. SAKINO and K. INOUE. IEEE Trans. Reliab. R-27, (5) 360 (December 1978). A Markov model is given for a class of series systems which have fault detectors to find component failures. The optimal allocation of fault detectors is determined. This problem is a nonlinear 0-1 integer programming (0-1 IP) problem. The problem is solved easily because the nonlinearity is of a special type. An illustrative example is given. A decomposition method for computing system reliability by a matrix expression. HAYAO NAKAZAWA. IEEE Trans. Reliab. R-27, (5) 342 (December 1978). A decomposition method using a matrix representation for computing the reliability of a redundant system is proposed. The system is decomposed into two subsystems according to up- and down-states of a keystone element. This is repeated recursively until all subsystems have known reliability. The criterion for choosing the keystoneelement and an algorithm for decomposing a system are described. Reliability based quality (RBQ) technique for evaluating the degradation of reliability during manufacturing. LEWIS NERI, VERNON ALLEN and RONALD ANDERSON. Microelectron. Reliab. 19, 117 (1979). Complex, modern day aviation systems such as Army helicopters require much more than sophisticated performance and versatility. Such systems demand high levels of field reliability to render their operation both safe and cost effective. To meet this need, a total life cycle reliability program is r e q u i r e d - o n e that does not stop after design and development but continues through production and field use. Only through a total life cycle program that is executed by well disciplined engineering methods and procedures, can safe, reliable, and economical helicopter systems be achieved. In order to assure that helicopter systems and components are reliable and cost-effective,a comprehensive methodology is being developed by the U.S. Army Aviation Research and Development Command (AVRADCOM). The basic framework for developing the methodology is defined in AVRADCOM's R & M management guidebook. The entire range of reliability engineering efforts as they relate to all phases of a helicopter's life cycle are covered in the guidebook. This paper addresses the production phase, which historically contributes to helicopter unreliability, and which traditionally has had no detailed reliability engineering procedures. It discusses how to assess and control the reliability of a helicopter system or component as it leaves production, by performing reliability and quality control analyses that account for production degradation factors due to manufacturing induced defects and imperfect inspection. The need for feedback of field RAM data. A. R. GILLIS. Microelectron. Reliab. 19, 89 (1979). Reliability has been an important factor in past wars and is becoming more prominent as equipment populations increase in size and complexity. This paper shows that RAM performance greatly affects life cycle cost and more importantly system effectiveness. It outlines aspects of the design process and casts doubt on the contractor's ability to understand or duplicate field conditions during development with a resultant disparity between achieved and predicted RAM performance. The paper concludes with a summary of information which should serve as design goals for any subsequent information system. Management of total reliability. S. C. PURl. Microelectron. Reliab. 19, 7 (1979). The ultimate goal of any quality program is to achieve such a state of process control that would continuously produce a high quality product that is satisfactory, reliable, and economical. To achieve this objective it is not enough to control only the technical
aspect of manufacturing/production process, but needs developing a total management system. Such a system would encompass all activities and functions associated with the development of quality, viz., quality control, quality assurance, and quality reliability. Many quality programs fail because they lack the essential elements of coordination and communication. Our contention is to suggest a simple model of a total management system--a system that is built essentially on the concept of incorporating a systematic integration and collective co-ordination of all elements of quality required towaros achieving the optimum goal. Most simply, a total quality management system essentially consists of three major components: management, technical, and statistical.
Management of satellite systems reliability program. FRANCOIS BEHMANN. Microelectron. Reliab. 19, 15 (1979). The management aspects of a reliability program are discussed relating to objectives, organization and program assurances. Satellite system reliability program basic activities are outlined including reliability considerations, requirements and achievement. A cost-effective satellite system configuration is briefly described. Finally, effective assurances and decision making for reliability program are discussed. A note on heuristic methods in optimal system reliability. WAY KUO, CHING-LAI HWANG and FRANK A. TILLMAN. IEEE Trans~ Reliab. R-27, (5) 320 (December 1978). Many optimization techniques have been used to solve redundancy allocation problems, most of which result in noninteger solutions. A few, including dynamic programming and integer programming, as well as a host of heuristic methods give integer solutions. This note critically reviews six promising heuristic approaches. The advantages and disadvantages of each of the approaches are discussed. An extended approach is presented which incorporates some of the ideas of the previous methods for solving a general non series-parallel system. The extended approach appears to be quite efficient and is general. The simplicity and efficiency of the approach will lend itself to solving large practical problems. Multiobjective optimization by the Surrogate Worth Tradeoff method. MASATOSH!SAKAWA.IEEE Trans. Reliab. R-27, (5) 311 (December 1978). This paper applies the Surrogate Worth Trade-off method to multiobjective reliabilityallocation problems. A multiobjective mathematical model is formulated and the problem is to assign reliability to each stage of a series system such that system reliability is maximized and cost is minimized, subject to multiple constraints. The preferred solution of the decision-maker is obtained by using the Surrogate Worth Trade-off method. A numerical example illustrates the efficiency of the proposed method. Although only a problem with two objectives is considered, more than two objectives can be tackled by the same approach. Effect of restricted repair on system reliability indices. R. BILLINTON and M. ALAM. IEEE Trans. Reliab. R-27, (5) 376 (December 1978). In many power system applications, two of the most practical indices of reliability assessment are the system average failure rate and the average outage duration. This paper illustrates the development of these indices for two dissimilar units connected in series and in parallel. The equations for a restricted repair condition are developed using the frequency and duration approach and compared with the known results for unrestricted repair. The only parameter which is appreciably affected by restricted repair is the average system outage duration when the two units operate in parallel. This paper develops an approximate and simple expression to evaluate this
World Abstracts on Microelectronics and Reliability
Optimal allocation of fault detectors. I. TAKAMI,T. INAGAKI, E. SAKINO and K. INOUE. IEEE Trans. Reliab. R-27, (5) 360 (December 1978). A Markov model is given for a class of series systems which have fault detectors to find component failures. The optimal allocation of fault detectors is determined. This problem is a nonlinear 0-1 integer programming (0-1 IP) problem. The problem is solved easily because the nonlinearity is of a special type. An illustrative example is given. A decomposition method for computing system reliability by a matrix expression. HAYAO NAKAZAWA. IEEE Trans. Reliab. R-27, (5) 342 (December 1978). A decomposition method using a matrix representation for computing the reliability of a redundant system is proposed. The system is decomposed into two subsystems according to up- and down-states of a keystone element. This is repeated recursively until all subsystems have known reliability. The criterion for choosing the keystoneelement and an algorithm for decomposing a system are described. Reliability based quality (RBQ) technique for evaluating the degradation of reliability during manufacturing. LEWIS NERI, VERNON ALLEN and RONALD ANDERSON. Microelectron. Reliab. 19, 117 (1979). Complex, modern day aviation systems such as Army helicopters require much more than sophisticated performance and versatility. Such systems demand high levels of field reliability to render their operation both safe and cost effective. To meet this need, a total life cycle reliability program is r e q u i r e d - o n e that does not stop after design and development but continues through production and field use. Only through a total life cycle program that is executed by well disciplined engineering methods and procedures, can safe, reliable, and economical helicopter systems be achieved. In order to assure that helicopter systems and components are reliable and cost-effective,a comprehensive methodology is being developed by the U.S. Army Aviation Research and Development Command (AVRADCOM). The basic framework for developing the methodology is defined in AVRADCOM's R & M management guidebook. The entire range of reliability engineering efforts as they relate to all phases of a helicopter's life cycle are covered in the guidebook. This paper addresses the production phase, which historically contributes to helicopter unreliability, and which traditionally has had no detailed reliability engineering procedures. It discusses how to assess and control the reliability of a helicopter system or component as it leaves production, by performing reliability and quality control analyses that account for production degradation factors due to manufacturing induced defects and imperfect inspection. The need for feedback of field RAM data. A. R. GILLIS. Microelectron. Reliab. 19, 89 (1979). Reliability has been an important factor in past wars and is becoming more prominent as equipment populations increase in size and complexity. This paper shows that RAM performance greatly affects life cycle cost and more importantly system effectiveness. It outlines aspects of the design process and casts doubt on the contractor's ability to understand or duplicate field conditions during development with a resultant disparity between achieved and predicted RAM performance. The paper concludes with a summary of information which should serve as design goals for any subsequent information system. Management of total reliability. S. C. PURl. Microelectron. Reliab. 19, 7 (1979). The ultimate goal of any quality program is to achieve such a state of process control that would continuously produce a high quality product that is satisfactory, reliable, and economical. To achieve this objective it is not enough to control only the technical
aspect of manufacturing/production process, but needs developing a total management system. Such a system would encompass all activities and functions associated with the development of quality, viz., quality control, quality assurance, and quality reliability. Many quality programs fail because they lack the essential elements of coordination and communication. Our contention is to suggest a simple model of a total management system--a system that is built essentially on the concept of incorporating a systematic integration and collective co-ordination of all elements of quality required towaros achieving the optimum goal. Most simply, a total quality management system essentially consists of three major components: management, technical, and statistical.
Management of satellite systems reliability program. FRANCOIS BEHMANN. Microelectron. Reliab. 19, 15 (1979). The management aspects of a reliability program are discussed relating to objectives, organization and program assurances. Satellite system reliability program basic activities are outlined including reliability considerations, requirements and achievement. A cost-effective satellite system configuration is briefly described. Finally, effective assurances and decision making for reliability program are discussed. A note on heuristic methods in optimal system reliability. WAY KUO, CHING-LAI HWANG and FRANK A. TILLMAN. IEEE Trans~ Reliab. R-27, (5) 320 (December 1978). Many optimization techniques have been used to solve redundancy allocation problems, most of which result in noninteger solutions. A few, including dynamic programming and integer programming, as well as a host of heuristic methods give integer solutions. This note critically reviews six promising heuristic approaches. The advantages and disadvantages of each of the approaches are discussed. An extended approach is presented which incorporates some of the ideas of the previous methods for solving a general non series-parallel system. The extended approach appears to be quite efficient and is general. The simplicity and efficiency of the approach will lend itself to solving large practical problems. Multiobjective optimization by the Surrogate Worth Tradeoff method. MASATOSH!SAKAWA.IEEE Trans. Reliab. R-27, (5) 311 (December 1978). This paper applies the Surrogate Worth Trade-off method to multiobjective reliabilityallocation problems. A multiobjective mathematical model is formulated and the problem is to assign reliability to each stage of a series system such that system reliability is maximized and cost is minimized, subject to multiple constraints. The preferred solution of the decision-maker is obtained by using the Surrogate Worth Trade-off method. A numerical example illustrates the efficiency of the proposed method. Although only a problem with two objectives is considered, more than two objectives can be tackled by the same approach. Effect of restricted repair on system reliability indices. R. BILLINTON and M. ALAM. IEEE Trans. Reliab. R-27, (5) 376 (December 1978). In many power system applications, two of the most practical indices of reliability assessment are the system average failure rate and the average outage duration. This paper illustrates the development of these indices for two dissimilar units connected in series and in parallel. The equations for a restricted repair condition are developed using the frequency and duration approach and compared with the known results for unrestricted repair. The only parameter which is appreciably affected by restricted repair is the average system outage duration when the two units operate in parallel. This paper develops an approximate and simple expression to evaluate this