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Constrained optimum test configuration for reliability acceptance tests incorporating environmental stresses
World Abstracts on Microelectronics and Reliability
Reliability optimization by 0-1 programming for a system with several failure modes. KWANG-NAM, Hyun (Mitsuo Geni. IEEE Trans. Reliab. R-24, 206 (1975). Mathematical models for reliability of a redundant system with two classes of failure modes are usually formulated as a nonlinear integer programming (NIP) problem. This paper reformulates the NIP problem into a 0-1 linear programming (ZOLP) problem and a one-to-one correspondence is shown between this NIP problem and the ZOLP problem. A NIP example treated by Tillman is formulated into a ZOLP problem and optimal solutions, identical to Tillman's are obtained by an implicit enumeration method. Calculating the new coefficients of the objective function and the constraints in the ZOLP are straightforward. There are not many constraints or variables in the proposed ZOLP. Consequently, the computation (CPU) time is less.
Constrained optimum test configuration for reliability acceptance tests incorporating environmental stresses. J. M. Mo(;ci. IEEE Trans. Reliab. R-24, 211 (1975). The cost of reliability acceptance testing can be more easily reduced by optimizing the parameters of the test rather than by relaxing the precision of the test. The test parameters are sample size, test configuration, and the duration of the test: the environmental stresses that are inherent in reliability testing are fixed. Optimization can be achieved when the various costs associated with the test are known, and limited resources of funds, time, and space constrain the tests.
Reliability bounds in probabilistic design. K. C. KAPUR. IEEE Trans. Reliab. R-24, 193 (1975). Reliability for probabilistic design and the simple stress-strength failure model depend only upon the interference of the stress and the strength random variables. This paper presents a methodology to compute bounds on the design reliability, given some bounds on probabilities over intervals of the overlapping tails of the stress and the strength random variables. Quadratic programming optimization is employed to find upper and lower bounds on reliability.
Needed for logic testing: a new breed of instruments. ANy SAgTONL Electronics. September 18th 1975. p. 88. For small-scale requirements, when computer control is not feasible, a number of new instruments are entering the field to make accurate fault analysis easier and less expensive. But more is wanted.
Is MIL-STD-781B a good reliability test specification. FRANK A. STOVAI_L. IEEE Trans. Reliab. August 1975. p. 166. This paper describes some of the advantages, shortcomings and recommended changes to MIL-STD-781B, which is a military specification for reliability test plans. Particular emphasis is given to laboratory discrepancies that are excluded from consideration as relevant failures. The principal reason that MIL-STD-781B test results do not reasonably foretell the minimum MTBF that can be expected in the field is that the field definition of failure is not compatible with the laboratory definition.
IC testing economics--in-house versus external testing services. B I L L COKER. Evaluation Engineering, July/August 1975. p. a26. At last, the electronic equipment industry has recognised the need for screening (preconditioning and testing) lC's before assembly into electronic equipment. Pre-conditioning steps, such as High Temperature Reverse Bias Burn-In, are no longer looked upon as a mysterious thing to try in order to eliminate failures that drastically increase equipment manufacturing costs. M&R I~/I--B
17
The question today is the economic consideration of developing a facility in-house versus contracting with an Independent Testing Facility.
Field Data Analysis via Markov Renewal Life Models. SHUN-ICHI ABE. Prec. Reliability and Maintainability Syrup. 28-30 p. 562 (January, 1975). On estimating the rare probability of failures of extremely reliable units, the field data of the units are very important. However. in their observation and analysis there are five pitfalls or difficulties specified. In order to overcome them a kind of Marker renewal life model is proposed and the notion of extended hazard is introduced. These enable us to take into account various maintenance informations and to estimate the mode-by-mode failure characteristics from short term observations of the stochastic processes of the units. The usefulness of the model and method is exemplified by the real field data.
Bayesian confdence limits for the availability of systems. W. E. THOMPSON and P. A. PALICIO. IEEE Trans. Reliab. R-24, 118 (1975). This paper presents a numerical procedure for computing Baves confidence intervals for the availability of a series or parallel system consisting of several statistically independent 2-state subsystems each having exponential distributions of life and repair time. The present results (1) provide a useful generalization of a previous result in which test data were limited to "snapshot" observations on the subsystems operating states; (2) allow conventional Iife-test data for estimating the exponential parameters. The methods are suited to numerical evaluation using electronic computers as shown by particular examples.
System reliability: exact Bayesian intervals compared with fiducial intervals. KATHRY~ P. BFRKm~n ER and JAMES K. BYERS. IEEE Trans. Reliab. R-24, 199 (1975). This paper compares numerically two different, widely used lower limit estimates for the reliability of a series system: Bayesian limits and fiducial limits. The fiducial limits are obtained by Monte Carlo simulation because of its simplicity and ease of computer programming. Subsystem failures are s-independent and exponentially distributed; life test data are available for estimating the failure rate of each system.
An introduction to fault tree analysis with emphasis on failure rate evaluation. G. W. E. NIEUWHOF. Prec. 1975. Canadian SRE Reliability SymposiunL May 10th, 1975. Ottawa. p. 105. The construction criteria and the two major evaluation methods of fault trees are briefly discussed. The equations of the basic logic units (OR-gate and AND-gate) of the tree are derived. The probability evaluation and the failure rate evaluation methods are each illustrated by means of a simple example. The effect of active redundancy on the failure rate of a system and its calculation methods are discussed in more detail.
Maintainability payoffs during weapon-system test: the value of appropriate testing. J. R NELSON. Proc Reliability and Maintainability Symposium. 28-31) January I975. Washington D . C . p . 26. A summary of lessons learned from a decade of experience in examining developmental and operational field tests of aircraft weapon systems is presented. An approach to reconcile design-to-cost and life-cycle cost in the context of maintainability payoffs during weapon-system test is discussed.
Economical attainment of high reliability. DI~RAID A. STUART. Prec. Reliability and Maintainability Symposium 28-30 January, 1975. Washington D.C.p. 418. Estimated reliability of the Poseidon missile system, at the onset of
Reliability optimization by 0-1 programming for a system with several failure modes. KWANG-NAM, Hyun (Mitsuo Geni. IEEE Trans. Reliab. R-24, 206 (1975). Mathematical models for reliability of a redundant system with two classes of failure modes are usually formulated as a nonlinear integer programming (NIP) problem. This paper reformulates the NIP problem into a 0-1 linear programming (ZOLP) problem and a one-to-one correspondence is shown between this NIP problem and the ZOLP problem. A NIP example treated by Tillman is formulated into a ZOLP problem and optimal solutions, identical to Tillman's are obtained by an implicit enumeration method. Calculating the new coefficients of the objective function and the constraints in the ZOLP are straightforward. There are not many constraints or variables in the proposed ZOLP. Consequently, the computation (CPU) time is less.
Constrained optimum test configuration for reliability acceptance tests incorporating environmental stresses. J. M. Mo(;ci. IEEE Trans. Reliab. R-24, 211 (1975). The cost of reliability acceptance testing can be more easily reduced by optimizing the parameters of the test rather than by relaxing the precision of the test. The test parameters are sample size, test configuration, and the duration of the test: the environmental stresses that are inherent in reliability testing are fixed. Optimization can be achieved when the various costs associated with the test are known, and limited resources of funds, time, and space constrain the tests.
Reliability bounds in probabilistic design. K. C. KAPUR. IEEE Trans. Reliab. R-24, 193 (1975). Reliability for probabilistic design and the simple stress-strength failure model depend only upon the interference of the stress and the strength random variables. This paper presents a methodology to compute bounds on the design reliability, given some bounds on probabilities over intervals of the overlapping tails of the stress and the strength random variables. Quadratic programming optimization is employed to find upper and lower bounds on reliability.
Needed for logic testing: a new breed of instruments. ANy SAgTONL Electronics. September 18th 1975. p. 88. For small-scale requirements, when computer control is not feasible, a number of new instruments are entering the field to make accurate fault analysis easier and less expensive. But more is wanted.
Is MIL-STD-781B a good reliability test specification. FRANK A. STOVAI_L. IEEE Trans. Reliab. August 1975. p. 166. This paper describes some of the advantages, shortcomings and recommended changes to MIL-STD-781B, which is a military specification for reliability test plans. Particular emphasis is given to laboratory discrepancies that are excluded from consideration as relevant failures. The principal reason that MIL-STD-781B test results do not reasonably foretell the minimum MTBF that can be expected in the field is that the field definition of failure is not compatible with the laboratory definition.
IC testing economics--in-house versus external testing services. B I L L COKER. Evaluation Engineering, July/August 1975. p. a26. At last, the electronic equipment industry has recognised the need for screening (preconditioning and testing) lC's before assembly into electronic equipment. Pre-conditioning steps, such as High Temperature Reverse Bias Burn-In, are no longer looked upon as a mysterious thing to try in order to eliminate failures that drastically increase equipment manufacturing costs. M&R I~/I--B
17
The question today is the economic consideration of developing a facility in-house versus contracting with an Independent Testing Facility.
Field Data Analysis via Markov Renewal Life Models. SHUN-ICHI ABE. Prec. Reliability and Maintainability Syrup. 28-30 p. 562 (January, 1975). On estimating the rare probability of failures of extremely reliable units, the field data of the units are very important. However. in their observation and analysis there are five pitfalls or difficulties specified. In order to overcome them a kind of Marker renewal life model is proposed and the notion of extended hazard is introduced. These enable us to take into account various maintenance informations and to estimate the mode-by-mode failure characteristics from short term observations of the stochastic processes of the units. The usefulness of the model and method is exemplified by the real field data.
Bayesian confdence limits for the availability of systems. W. E. THOMPSON and P. A. PALICIO. IEEE Trans. Reliab. R-24, 118 (1975). This paper presents a numerical procedure for computing Baves confidence intervals for the availability of a series or parallel system consisting of several statistically independent 2-state subsystems each having exponential distributions of life and repair time. The present results (1) provide a useful generalization of a previous result in which test data were limited to "snapshot" observations on the subsystems operating states; (2) allow conventional Iife-test data for estimating the exponential parameters. The methods are suited to numerical evaluation using electronic computers as shown by particular examples.
System reliability: exact Bayesian intervals compared with fiducial intervals. KATHRY~ P. BFRKm~n ER and JAMES K. BYERS. IEEE Trans. Reliab. R-24, 199 (1975). This paper compares numerically two different, widely used lower limit estimates for the reliability of a series system: Bayesian limits and fiducial limits. The fiducial limits are obtained by Monte Carlo simulation because of its simplicity and ease of computer programming. Subsystem failures are s-independent and exponentially distributed; life test data are available for estimating the failure rate of each system.
An introduction to fault tree analysis with emphasis on failure rate evaluation. G. W. E. NIEUWHOF. Prec. 1975. Canadian SRE Reliability SymposiunL May 10th, 1975. Ottawa. p. 105. The construction criteria and the two major evaluation methods of fault trees are briefly discussed. The equations of the basic logic units (OR-gate and AND-gate) of the tree are derived. The probability evaluation and the failure rate evaluation methods are each illustrated by means of a simple example. The effect of active redundancy on the failure rate of a system and its calculation methods are discussed in more detail.
Maintainability payoffs during weapon-system test: the value of appropriate testing. J. R NELSON. Proc Reliability and Maintainability Symposium. 28-31) January I975. Washington D . C . p . 26. A summary of lessons learned from a decade of experience in examining developmental and operational field tests of aircraft weapon systems is presented. An approach to reconcile design-to-cost and life-cycle cost in the context of maintainability payoffs during weapon-system test is discussed.
Economical attainment of high reliability. DI~RAID A. STUART. Prec. Reliability and Maintainability Symposium 28-30 January, 1975. Washington D.C.p. 418. Estimated reliability of the Poseidon missile system, at the onset of