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Approximate system availability models
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W O R L DABSTRACTS ON MICROELECTRONICS
AND RELIABILITY
Quality standards for large-scale integration [LSI]. L. HAMITER,Mikroelektronik 3. Publ. by R. Oldenbourg. Munchen, Gelmany (1969), p. 387. Large-scale integration is the incorporation of a large number of devices (transistors, diodes and resistors) and functions on a single integrated circuit chip or wafer. As the designer can create and apply more functions on one chip, its degree of specialization increases, thereby resulting in custom design for each circuit. For a system designer to put his trust on LSI circuits, the circuits must come up to the realm of unquestionable quality and reliability. This paper proposes quality standards for LSI, both bipolar and metal-oxide-semiconductor (MOS).
Precision testing of thin-film resistors. F. E. MALLETT,Electron. Compon., March (1969), p. 312. Tantalum alloy thin-film circuits offering a very high order of reliability in severe environments are now in quantity production at Ultra Electronics (Components) Ltd. The use of vacuum sputtered tantalum alloys for resistive elements provides sufficient accuracy for many applications without further adjustment, while trimming techniques using a d.c. current calibrator supplied by G. & E. Bradley Ltd. enable accuracies of 4-0.5 per cent to be readily maintained on the production line. Equipment for trimming to greater accuracies is under development. 3. CIRCUIT AND SYSTEMS RELIABILITY, MAINTENANCE AND REDUNDANCY Suggested improvements for maintainability demonstrations. J. E. DAVEAU, Proc. 1969 Ann. Symp. Reliab., Chicago, Illinois, 21-23 January (1969), p. 572. This paper first discusses current maintainability demonstration techniques; then, based on actual field data and the author's personal experience, examines the weakness in current "simulated" type of maintainability demonstration. Recommendations are included which will significantly improve demonstration measurement. Actual system mean time to repair (MTTR) field data is analyzed for mathematical distribution, range and upper and lower limits. This data is discussed further from the standpoint of field (collection of actual M T T R events as they occur) maintainability demonstrations, and conclusions are presented regarding the testing. Environmental testing--the key to high reliability. R. L. VAN DER HAMM, Proc. 1969 Ann. Syrup. Reliab., Chicago, Illinois, 21-23 January (1969), p. 27. This paper describes experiences with, and general results of, MIL-STD-781 (AGREE) testing on many military and commercial equipment types during the past 10 years. The benefits of AGREE testing are delineated and emphasized are the disciplines necessary to realize the maximum benefits from applying this testing philosophy. Its application to reliability evaluation, demonstration and burn-in testing is also discussed. The adoption of AGREE testing as a standard practice during the development and manufacturing phases of commercial electronic equipment program is also described. Economic benefits are explained. Recommendations are presented to the military and the commercial segment of the electronic industry, which, if followed, will result in more efficient and effective utilization of the AGREE testing philosophy. Approximate system availability models. K. GRACE,JR., Proc. 1969 Ann. Symp. Reliab., Chicago, Illinois, 21-23 January (1969), p. 146. This paper considers the evaluation of steady-state system availability when there are a limited number of repairable spares for the various types of outline units. The spare supply creates a statistical dependence among units of a given type. System availability is expressed in terms of unit availabilities using a procedure adapted from work of Messinger and Shooman. Availabilities of various numbers of units of a given type are obtained from an exact Markov model and from several approximate models. The models are compared by means of some simple examples. Progress in on-line control by computer. D. BEST, Radio Electron. Engr, February (1969), p. 85. The paper presents an account of the development of industrial process control by computer. Some of the control functions carried out by computer are described, with examples from a number of industrial processes. The special features of digital equipment for on-line industrial use are examined. In particular, reliability and fail-safe aspects are emphasized. Some of the methods used and problems encountered in system design and programming activities are illustrated.
W O R L DABSTRACTS ON MICROELECTRONICS
AND RELIABILITY
Quality standards for large-scale integration [LSI]. L. HAMITER,Mikroelektronik 3. Publ. by R. Oldenbourg. Munchen, Gelmany (1969), p. 387. Large-scale integration is the incorporation of a large number of devices (transistors, diodes and resistors) and functions on a single integrated circuit chip or wafer. As the designer can create and apply more functions on one chip, its degree of specialization increases, thereby resulting in custom design for each circuit. For a system designer to put his trust on LSI circuits, the circuits must come up to the realm of unquestionable quality and reliability. This paper proposes quality standards for LSI, both bipolar and metal-oxide-semiconductor (MOS).
Precision testing of thin-film resistors. F. E. MALLETT,Electron. Compon., March (1969), p. 312. Tantalum alloy thin-film circuits offering a very high order of reliability in severe environments are now in quantity production at Ultra Electronics (Components) Ltd. The use of vacuum sputtered tantalum alloys for resistive elements provides sufficient accuracy for many applications without further adjustment, while trimming techniques using a d.c. current calibrator supplied by G. & E. Bradley Ltd. enable accuracies of 4-0.5 per cent to be readily maintained on the production line. Equipment for trimming to greater accuracies is under development. 3. CIRCUIT AND SYSTEMS RELIABILITY, MAINTENANCE AND REDUNDANCY Suggested improvements for maintainability demonstrations. J. E. DAVEAU, Proc. 1969 Ann. Symp. Reliab., Chicago, Illinois, 21-23 January (1969), p. 572. This paper first discusses current maintainability demonstration techniques; then, based on actual field data and the author's personal experience, examines the weakness in current "simulated" type of maintainability demonstration. Recommendations are included which will significantly improve demonstration measurement. Actual system mean time to repair (MTTR) field data is analyzed for mathematical distribution, range and upper and lower limits. This data is discussed further from the standpoint of field (collection of actual M T T R events as they occur) maintainability demonstrations, and conclusions are presented regarding the testing. Environmental testing--the key to high reliability. R. L. VAN DER HAMM, Proc. 1969 Ann. Syrup. Reliab., Chicago, Illinois, 21-23 January (1969), p. 27. This paper describes experiences with, and general results of, MIL-STD-781 (AGREE) testing on many military and commercial equipment types during the past 10 years. The benefits of AGREE testing are delineated and emphasized are the disciplines necessary to realize the maximum benefits from applying this testing philosophy. Its application to reliability evaluation, demonstration and burn-in testing is also discussed. The adoption of AGREE testing as a standard practice during the development and manufacturing phases of commercial electronic equipment program is also described. Economic benefits are explained. Recommendations are presented to the military and the commercial segment of the electronic industry, which, if followed, will result in more efficient and effective utilization of the AGREE testing philosophy. Approximate system availability models. K. GRACE,JR., Proc. 1969 Ann. Symp. Reliab., Chicago, Illinois, 21-23 January (1969), p. 146. This paper considers the evaluation of steady-state system availability when there are a limited number of repairable spares for the various types of outline units. The spare supply creates a statistical dependence among units of a given type. System availability is expressed in terms of unit availabilities using a procedure adapted from work of Messinger and Shooman. Availabilities of various numbers of units of a given type are obtained from an exact Markov model and from several approximate models. The models are compared by means of some simple examples. Progress in on-line control by computer. D. BEST, Radio Electron. Engr, February (1969), p. 85. The paper presents an account of the development of industrial process control by computer. Some of the control functions carried out by computer are described, with examples from a number of industrial processes. The special features of digital equipment for on-line industrial use are examined. In particular, reliability and fail-safe aspects are emphasized. Some of the methods used and problems encountered in system design and programming activities are illustrated.