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More accurate maintainability predictions
576
World Abstracts on Microelectronics and Reliability
out-of-n systems in i.i.d. IFR components proven by Barlow and Proschan cannot be extended to all s-coherent systems. The class of s-coherent systems for which such closure obtains is characterized.
Present worth of service cost for consumer product warranty. KYUNG S. PARK and SEUNG R. YEE. IEEE Trans. Reliab. R33 (5) 424 (December 1984). Under a warranty service contract, the manufacturer of a consumer product agrees to repair and maintain the product over a certain stated period of time for a fee from the customer. The manufacturer offering such a service contract is faced with several policy design and planning decisions. Mathematical models of product failures and of future repair costs are basic to the formulation of these decision problems. We assume Weibull time-to-failure distribution for analytic amenability and reasonable realism. A repair returns the product to the average condition for a working unit of its age (bad as old). Simple stochastic models of sequences of failures and their costs are developed. Expressions are obtained for the s-expectation of the present worth of the future repair costs. Nonlinear integer goal programming applied to optimal system reliability. C. L. HWANG, HOON BYUNG LEE, F. A. TILLMAN and CHANG HOON LIE. IEEE Trans. Reliab. R-33 (5) 431 (December 1984). Few studies have been done on techniques to solve multiple objective nonlinear integer problems. This paper formulates an algorithm for nonlinear integer goal .programming using a branch-and-bound method and Hwang & Masud's nonlinear goal programming method. The application of this algorithm is demonstrated by solving reliability problems with single and multiple objectives. The single objective nonlinear integer problem is solved by the nonlinear integer goal programming taking the constraints at priority level one and the objective at priority level two. One interesting feature in this algorithm is that the problem is solved by traditional nonlinear search techniques, such as Hooke and Jeeves pattern search, that are originally intended for solving the "unconstrained' problem. However, there is no way to guarantee finding the global optimum for a given problem. This means that the investigator must usually be satisfied with a local optimum or a set of local optima. Quantile estimates in complete and censored samples from extreme-value and Weibuil distributions. KHATAB M. HASSANEIN, m. K. MD. EHSANES SALEH and EDWARD F. BROWN. 1EEE Trans. Reliab. R-33 (5) 370 (December 1984). This paper deals with the problem of estimating the quantiles (0 = 0.01, 0.05(0.05)0.95, 0.99 of the largest extreme-value distribution by using order statistics in small samples. Linear unbiased estimators, with minimum variance, based on ordered observations are constructed for sample sizes 5(5)20 for both complete and right-censored samples. Normal probability plotting--a tool for trouble shooting. P. K. PERUMALLU.QR J., India. 103 (September 1984). The use of the Normal Probability Plotting as a simple tool for getting quantitative information on process setting, standard deviation and percentage nonconformance in production, with a case study, has been considered in this paper. More accurate maintainability predictions. DAVID BAKKEN and JAMESM. BANGHART.Proc. a. Reliab. Maintanab. Syrup. 44 (1985). Computer programs that perform the calculations to complete a maintanability prediction are in frequent use. These programs can and should easily accommodate analysis which is not practical for manual maintainability predictions. Among the more sophisticated analysis capabilities are the handling of probabifistic task times in the calculation of task time distributions, and the ability to analyze multiple levels of repair performed at the same repair facility.
Correct the process, not the product. TIM FULLER. Electron. Prod. 73 (September ]984). Thirteen months after Hewlett Packard implemented its statistical quality control (SQC) in manufacturing, dramatic gains were made both in quality and productivity, Polyimide discoloration--a failure analysis study. T. E. SVARNEY and J. F. TURNER. Solid St. Technol. 171 (January 1985). PMDA-ODA polyimide samples exhibited a brown discoloration after curing. The samples were slides coated with the polyimide film; they were examined using optical and surface analysis techniques. A comparison study was done to determine the cause of the polyimide discoloration. Results of the study Were correlated with the data obtained from the original discolored samples. The brown polyimide discoloration was caused by residual negative resist strip solution, This solution reacts with the polyamic acid to form an altered structure which cannot be fully imidized during cure. A brown discoloration results. A low-cost concept for the testing of microprocessorcontrolled assemblies. D. FUNKE and G. W. WOSTENKUHLER. Feinwerktechnik Messtechnik 92 (8) 385 (1984) (in German). Over the past years the use of microprocessors has steadily increased the trend is continuing. Already today, there is hardly an electronic device which is not equipped with one of these intelligent chips. This report describes the concept, device structure and software of an economical testing system on a personal-computer-basis and shows its practical application in a specific microelectronic assembly group. Models for the reliability of memory with ECC. ROBERT A. RUTLEDGE. Proc. a. Reliab. Maintainab. Syrup. 57 (1985). This paper reviews a number of analytic techniques for evaluating the reliability of memory with single-error correction. The techniques for computing Rm(t), the memory reliability function, can be divided into three basic models, depending on the nature and number of simultaneously acting failure modes. Other measures of system reliability, such as the MTTF, hazard rate and uncorrectable error rate, are derived from Rm(t). Finally, the effect of soft errors on memory reliability is considered. Relating factory and field reliability and maintainability measures. PRESTON R. MACDIARMID. Proc. a. Reliab. Maintainab. Syrup. 177 (1985). This paper addresses the issue of field reliability not equaling factory reliability. It overviews Air Force and DOD policy on the issue, reviews previous works on the subject and details current Rome Air Development Center activities related to it, including a recently completed study that developed models translating contractual to operational (and vice versa) R&M parameters. AV-8B design for maintainability. RAYMONDJ. ANDERSON. Proc. a. Reliab. Maintainab. Symp. 28 (1985). This paper identifies methods, procedures, and design features used to create a maintainable and effective AV-8B light attack Vertical/Short Takeoff and Landing (V/STOL) aircraft for operations from all classes of carriers, VTOL ships/sea platforms, shore bases, and forward sites. The AV-8B combines the vectored thrust concept of the AV-8A with a new, larger wing, simple lift improvement device and other improvements which result in twice the payload or radius capability, improved weapon delivery accuracy, improved readiness, increased effectiveness, and lower cost of ownership. The challenge has been to achieve significant contractually specified maintainability improvements while utilizing the inherent qualities of the AV-8A in an austere funding environment. The initial effort concentrated on: detailed analysis of the AV-8A to establish areas of enhancement, investigation of high yield technology for AV8B application, and the establishment of best mix of new and existing equipment.
World Abstracts on Microelectronics and Reliability
out-of-n systems in i.i.d. IFR components proven by Barlow and Proschan cannot be extended to all s-coherent systems. The class of s-coherent systems for which such closure obtains is characterized.
Present worth of service cost for consumer product warranty. KYUNG S. PARK and SEUNG R. YEE. IEEE Trans. Reliab. R33 (5) 424 (December 1984). Under a warranty service contract, the manufacturer of a consumer product agrees to repair and maintain the product over a certain stated period of time for a fee from the customer. The manufacturer offering such a service contract is faced with several policy design and planning decisions. Mathematical models of product failures and of future repair costs are basic to the formulation of these decision problems. We assume Weibull time-to-failure distribution for analytic amenability and reasonable realism. A repair returns the product to the average condition for a working unit of its age (bad as old). Simple stochastic models of sequences of failures and their costs are developed. Expressions are obtained for the s-expectation of the present worth of the future repair costs. Nonlinear integer goal programming applied to optimal system reliability. C. L. HWANG, HOON BYUNG LEE, F. A. TILLMAN and CHANG HOON LIE. IEEE Trans. Reliab. R-33 (5) 431 (December 1984). Few studies have been done on techniques to solve multiple objective nonlinear integer problems. This paper formulates an algorithm for nonlinear integer goal .programming using a branch-and-bound method and Hwang & Masud's nonlinear goal programming method. The application of this algorithm is demonstrated by solving reliability problems with single and multiple objectives. The single objective nonlinear integer problem is solved by the nonlinear integer goal programming taking the constraints at priority level one and the objective at priority level two. One interesting feature in this algorithm is that the problem is solved by traditional nonlinear search techniques, such as Hooke and Jeeves pattern search, that are originally intended for solving the "unconstrained' problem. However, there is no way to guarantee finding the global optimum for a given problem. This means that the investigator must usually be satisfied with a local optimum or a set of local optima. Quantile estimates in complete and censored samples from extreme-value and Weibuil distributions. KHATAB M. HASSANEIN, m. K. MD. EHSANES SALEH and EDWARD F. BROWN. 1EEE Trans. Reliab. R-33 (5) 370 (December 1984). This paper deals with the problem of estimating the quantiles (0 = 0.01, 0.05(0.05)0.95, 0.99 of the largest extreme-value distribution by using order statistics in small samples. Linear unbiased estimators, with minimum variance, based on ordered observations are constructed for sample sizes 5(5)20 for both complete and right-censored samples. Normal probability plotting--a tool for trouble shooting. P. K. PERUMALLU.QR J., India. 103 (September 1984). The use of the Normal Probability Plotting as a simple tool for getting quantitative information on process setting, standard deviation and percentage nonconformance in production, with a case study, has been considered in this paper. More accurate maintainability predictions. DAVID BAKKEN and JAMESM. BANGHART.Proc. a. Reliab. Maintanab. Syrup. 44 (1985). Computer programs that perform the calculations to complete a maintanability prediction are in frequent use. These programs can and should easily accommodate analysis which is not practical for manual maintainability predictions. Among the more sophisticated analysis capabilities are the handling of probabifistic task times in the calculation of task time distributions, and the ability to analyze multiple levels of repair performed at the same repair facility.
Correct the process, not the product. TIM FULLER. Electron. Prod. 73 (September ]984). Thirteen months after Hewlett Packard implemented its statistical quality control (SQC) in manufacturing, dramatic gains were made both in quality and productivity, Polyimide discoloration--a failure analysis study. T. E. SVARNEY and J. F. TURNER. Solid St. Technol. 171 (January 1985). PMDA-ODA polyimide samples exhibited a brown discoloration after curing. The samples were slides coated with the polyimide film; they were examined using optical and surface analysis techniques. A comparison study was done to determine the cause of the polyimide discoloration. Results of the study Were correlated with the data obtained from the original discolored samples. The brown polyimide discoloration was caused by residual negative resist strip solution, This solution reacts with the polyamic acid to form an altered structure which cannot be fully imidized during cure. A brown discoloration results. A low-cost concept for the testing of microprocessorcontrolled assemblies. D. FUNKE and G. W. WOSTENKUHLER. Feinwerktechnik Messtechnik 92 (8) 385 (1984) (in German). Over the past years the use of microprocessors has steadily increased the trend is continuing. Already today, there is hardly an electronic device which is not equipped with one of these intelligent chips. This report describes the concept, device structure and software of an economical testing system on a personal-computer-basis and shows its practical application in a specific microelectronic assembly group. Models for the reliability of memory with ECC. ROBERT A. RUTLEDGE. Proc. a. Reliab. Maintainab. Syrup. 57 (1985). This paper reviews a number of analytic techniques for evaluating the reliability of memory with single-error correction. The techniques for computing Rm(t), the memory reliability function, can be divided into three basic models, depending on the nature and number of simultaneously acting failure modes. Other measures of system reliability, such as the MTTF, hazard rate and uncorrectable error rate, are derived from Rm(t). Finally, the effect of soft errors on memory reliability is considered. Relating factory and field reliability and maintainability measures. PRESTON R. MACDIARMID. Proc. a. Reliab. Maintainab. Syrup. 177 (1985). This paper addresses the issue of field reliability not equaling factory reliability. It overviews Air Force and DOD policy on the issue, reviews previous works on the subject and details current Rome Air Development Center activities related to it, including a recently completed study that developed models translating contractual to operational (and vice versa) R&M parameters. AV-8B design for maintainability. RAYMONDJ. ANDERSON. Proc. a. Reliab. Maintainab. Symp. 28 (1985). This paper identifies methods, procedures, and design features used to create a maintainable and effective AV-8B light attack Vertical/Short Takeoff and Landing (V/STOL) aircraft for operations from all classes of carriers, VTOL ships/sea platforms, shore bases, and forward sites. The AV-8B combines the vectored thrust concept of the AV-8A with a new, larger wing, simple lift improvement device and other improvements which result in twice the payload or radius capability, improved weapon delivery accuracy, improved readiness, increased effectiveness, and lower cost of ownership. The challenge has been to achieve significant contractually specified maintainability improvements while utilizing the inherent qualities of the AV-8A in an austere funding environment. The initial effort concentrated on: detailed analysis of the AV-8A to establish areas of enhancement, investigation of high yield technology for AV8B application, and the establishment of best mix of new and existing equipment.