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Using certified test records
World Abstracts on Microelectronics and Reliability 490 (1979) (in German). The problem of the Iocalisation of faults at electronic circuits is a problem of the pattern recognition and can be taken back to a set-theoretical task. By connection (averaging) of fault causes a fault Iocalisation is possible. A special method of the pattern recognition is represented. Signature analysis wins new acclaim. MARTIN MARSHALL. Electronics. p. 102 (14 February 1980). Discovery that the "field service technique of the '80s" can be retroflited erases early disappointment.
A computer method for fault detection in combinational cirCull& SURESH RAt and K. K. AGGARWAL.Internat. J. Electron. 47 (3) 247 (1979). In this paper a computer method for fault detection using Boolean matrices has been proposed. The method is computationally advantageous and it also defines the normal output of the circuit for all stuck-line faults. A computer program using Fortran IV, which is successfully tried on TDC-316 computer is also given. An example illustrates the method. Memory finds and fixes errors to raise reliability of microcomputer. ALAN HEIMLICH and JOEL KORELITZ. Electronics p. 168 (3 January i980). Using a Hamming code scheme lets byte- and word-wide memory boards correct single-bit errors, tell system to act when double-bit errors occur. Using certified test records. T. WAGSTAFFE. Electron. Product. p. 26 (January 1980). The certified test record is a summary of test results and includes information derived from endurance tests. The CTR is issued each 6 month period by the manufacturer of his approved component and summarises the results of Groups A (Final Acceptance) B (Lot by Lot) C and D (Environmental and Endurance) testing. The results are reported in two f o r m s (a) the current 6 month period and (b) the current 3 yr period (including the current 6 months). Calculation of system reliability by algebraic manipulation of probability expressions. T. B. BOFFEY and R. J. M. WATERS. IEEE Trans. Reliab. R-28, (5) 358 (December 1979). The method of synthesis for calculating the reliability of a complex network was developed by Woodcock. However, he experienced some difficulty in properly incorporating s-dependency, and this often necessitated considerable manipulation of the network beforehand. This difficulty is overcome in the present method by working with algebraic expressions involving component failure probabilities, and combining these expressions according to a simple set of rules. Experimental results are encouraging. Optimal seheduled-maintenance policy based on multiplecriteria declsion-making. C. L. HWANG, F. A. TILLMAN, W. K. WEt and C. H. Lm. IEEE Trans. Reliab. R-28, (5) 394 (December 1979). Usually, more than one independent (conflicting) criterion is important in determining the replacement age of a critical item for a maintained system. In this study, mathematical models have been developed for three such criteria: 1) minimum replacement cost-rate, 2) maximum availability, and 3) lower-bound on mission reliability. The solutions are obtained using four methods for multiple criteria decision making: 1) strictest-selection, 2) lexicographic, 3) Waltz lexicographic, and 4) sequential multiple-objective problem-solving technique (SEMOPS). Using an aircraft engine as an example, the optimal replacement age has been found by the four different methods. The results and the implications of the methods are discussed.
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Apportionment of overall system reliability among subsystems. ROLF MULLER and GUNTER VOLLHARDT. Frequenz 34, (1) 25 (1980) (in German). Communication satellites are required to have a specific survival probability for a given mission time. This reliability requirement must be apportioned amongst the individual subsystems. Mathematical methods for determining reliability apportionment are described. An efficient bottom-up algorithm for enumerating minimal cut sets of fault trees, KYOICHI NAKASHIMA and YOSHIO HA'rrORI. IEEE Trans. Reliab. R-28, (5) 353 (December 1979). The paper improves the conventional bottom-up algorithm for enumerating minimal cut sets of fault tree. It is proved that, when the logical product of two reduced sum-of-product forms is expanded by the distribution rule, one need only check if each resulting term is absorbed by some terms of two original sum-of-product forms. The algorithm for executing this process is presented and illustrated by an example. The entire computer program is given in a supplement and the computational results for sevei'al examples are presented to demonstrate the efficiency of the algorithm. Reliability analysis of 3-state systems. YUKIO HATOYAMA. IEEE Trans. Reliab. R-28, (5) 386 (December 1979). This paper describes a reliability analysis of a system where its components take one of three states--good, degraded, or bad. For this 3-state system, the analogy of 2-state system is investigated. The calculation of system reliability can be reduced to that of the reliability of a corresponding 2-stat~; system, provided that it is a generalized S-P system, with or without artificial, degraded components. Consequently, methods for evaluating the exact system reliability and useful bounds on system reliability of 2-state s-coherent system directly apply to 3-state systems. Some basic properties of system reliability with s-independent components are then presented. Further, some reliability bounds on systems with s-associated components are derived. Finally, the method is extended to multi-statE' systems. This state reduction can be used somewhat in analyzing models where time plays a role.
Computer simulation of system testing strategies for fault elimination. J. M. KONTOLEON. IEEE Trans. Reliab. R-28, (5) 407 (December 1979). This paper deals with the optimum testing strategy for systems organized into a number of cascaded modules; the strategy gives the minimum s-expected number of tests for eliminating all faulty modules. A single test is carried out by exciting the input of the system and measuring all of the output terminals of one module. Testing continues until all faulty modules are replaced by known good ones. A computer simulation is used to generate an optimal or near-optimal sequence of tests; this depends on the number of modules, their probabilities of success, and the relative position of the modules. Inverting and minimizing Boolean functions, minimal paths and minimal cuts: noncoherent system analysis. MITCHELL O. LOCKS. IEEE Trans. Reliab. R-28, (5) 373 (December 1979). An efficient technique is presented for inverting the minimal paths of a reliability logic diagram or fault tree, and then minimizing to obtain the minimal cuts, or else inverting the minimal cuts for the minimal paths. The method is appropriate for both s-coherent and s-noncoherent systems; it can also obtain the minimized dual inverse of any Boolean function. Inversion is more complex with s-noncoherence than with s-coherence because the minimal form (m.f.) is not uniqt~e. The result of inversion is the dual prime implicants (p.i.'s). The terms of a dual m.f., the dual minimal states, are obtained by a search process. First the dual p.i.'s are obtained; then a m.f. is found by an
A computer method for fault detection in combinational cirCull& SURESH RAt and K. K. AGGARWAL.Internat. J. Electron. 47 (3) 247 (1979). In this paper a computer method for fault detection using Boolean matrices has been proposed. The method is computationally advantageous and it also defines the normal output of the circuit for all stuck-line faults. A computer program using Fortran IV, which is successfully tried on TDC-316 computer is also given. An example illustrates the method. Memory finds and fixes errors to raise reliability of microcomputer. ALAN HEIMLICH and JOEL KORELITZ. Electronics p. 168 (3 January i980). Using a Hamming code scheme lets byte- and word-wide memory boards correct single-bit errors, tell system to act when double-bit errors occur. Using certified test records. T. WAGSTAFFE. Electron. Product. p. 26 (January 1980). The certified test record is a summary of test results and includes information derived from endurance tests. The CTR is issued each 6 month period by the manufacturer of his approved component and summarises the results of Groups A (Final Acceptance) B (Lot by Lot) C and D (Environmental and Endurance) testing. The results are reported in two f o r m s (a) the current 6 month period and (b) the current 3 yr period (including the current 6 months). Calculation of system reliability by algebraic manipulation of probability expressions. T. B. BOFFEY and R. J. M. WATERS. IEEE Trans. Reliab. R-28, (5) 358 (December 1979). The method of synthesis for calculating the reliability of a complex network was developed by Woodcock. However, he experienced some difficulty in properly incorporating s-dependency, and this often necessitated considerable manipulation of the network beforehand. This difficulty is overcome in the present method by working with algebraic expressions involving component failure probabilities, and combining these expressions according to a simple set of rules. Experimental results are encouraging. Optimal seheduled-maintenance policy based on multiplecriteria declsion-making. C. L. HWANG, F. A. TILLMAN, W. K. WEt and C. H. Lm. IEEE Trans. Reliab. R-28, (5) 394 (December 1979). Usually, more than one independent (conflicting) criterion is important in determining the replacement age of a critical item for a maintained system. In this study, mathematical models have been developed for three such criteria: 1) minimum replacement cost-rate, 2) maximum availability, and 3) lower-bound on mission reliability. The solutions are obtained using four methods for multiple criteria decision making: 1) strictest-selection, 2) lexicographic, 3) Waltz lexicographic, and 4) sequential multiple-objective problem-solving technique (SEMOPS). Using an aircraft engine as an example, the optimal replacement age has been found by the four different methods. The results and the implications of the methods are discussed.
543
Apportionment of overall system reliability among subsystems. ROLF MULLER and GUNTER VOLLHARDT. Frequenz 34, (1) 25 (1980) (in German). Communication satellites are required to have a specific survival probability for a given mission time. This reliability requirement must be apportioned amongst the individual subsystems. Mathematical methods for determining reliability apportionment are described. An efficient bottom-up algorithm for enumerating minimal cut sets of fault trees, KYOICHI NAKASHIMA and YOSHIO HA'rrORI. IEEE Trans. Reliab. R-28, (5) 353 (December 1979). The paper improves the conventional bottom-up algorithm for enumerating minimal cut sets of fault tree. It is proved that, when the logical product of two reduced sum-of-product forms is expanded by the distribution rule, one need only check if each resulting term is absorbed by some terms of two original sum-of-product forms. The algorithm for executing this process is presented and illustrated by an example. The entire computer program is given in a supplement and the computational results for sevei'al examples are presented to demonstrate the efficiency of the algorithm. Reliability analysis of 3-state systems. YUKIO HATOYAMA. IEEE Trans. Reliab. R-28, (5) 386 (December 1979). This paper describes a reliability analysis of a system where its components take one of three states--good, degraded, or bad. For this 3-state system, the analogy of 2-state system is investigated. The calculation of system reliability can be reduced to that of the reliability of a corresponding 2-stat~; system, provided that it is a generalized S-P system, with or without artificial, degraded components. Consequently, methods for evaluating the exact system reliability and useful bounds on system reliability of 2-state s-coherent system directly apply to 3-state systems. Some basic properties of system reliability with s-independent components are then presented. Further, some reliability bounds on systems with s-associated components are derived. Finally, the method is extended to multi-statE' systems. This state reduction can be used somewhat in analyzing models where time plays a role.
Computer simulation of system testing strategies for fault elimination. J. M. KONTOLEON. IEEE Trans. Reliab. R-28, (5) 407 (December 1979). This paper deals with the optimum testing strategy for systems organized into a number of cascaded modules; the strategy gives the minimum s-expected number of tests for eliminating all faulty modules. A single test is carried out by exciting the input of the system and measuring all of the output terminals of one module. Testing continues until all faulty modules are replaced by known good ones. A computer simulation is used to generate an optimal or near-optimal sequence of tests; this depends on the number of modules, their probabilities of success, and the relative position of the modules. Inverting and minimizing Boolean functions, minimal paths and minimal cuts: noncoherent system analysis. MITCHELL O. LOCKS. IEEE Trans. Reliab. R-28, (5) 373 (December 1979). An efficient technique is presented for inverting the minimal paths of a reliability logic diagram or fault tree, and then minimizing to obtain the minimal cuts, or else inverting the minimal cuts for the minimal paths. The method is appropriate for both s-coherent and s-noncoherent systems; it can also obtain the minimized dual inverse of any Boolean function. Inversion is more complex with s-noncoherence than with s-coherence because the minimal form (m.f.) is not uniqt~e. The result of inversion is the dual prime implicants (p.i.'s). The terms of a dual m.f., the dual minimal states, are obtained by a search process. First the dual p.i.'s are obtained; then a m.f. is found by an