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Space shuttle component reuse study
World Abstracts on Microelectronics and Reliability
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method of moments is used to lit the distributions. A comparison of posterior producer and consumer risks in a Bayesian reliability demonstration test is made using the fitted inverted gamma and uniform distributions as the priors. There can be rather large differences in the values of the posterior risks even when the two priors fit the data equally well or equally poorly.
Several studies have been performed with the ALE model, and one in particular is discussed in this paper. In this case, Hughes recommended 27 separate reliability and maintainability improvements to the AWG-9; AWM-23 systems. The contribution of these improvements to F-14 availability is discussed, with particular emphasis on achieved crisis-flight rate.
An efficient algorithm for deducing the minimal cuts and reliability indices of a general network configuration. R. N. ALLAY, R. BH.HXroN and M. 1-. DE OLWEmA. IEEE Trans. Reliah. R-25 (4), 226 (October 1976). The paper describes an efficient algorithm for evaluating the minimal cut sets of any general network. The algorithm is based on Boolean algebra and set theory, and contains many important improvements. The four most important features are 1. only one set of topological input data is required to evaluate the minimal cuts and reliability indices of every output node; 2. a mix of undirectional and multi ended components can bc included very simply; 3. any number of input nodes may be specified; 4. a new concept of overall system reliability permits different, large, and complex systems to be compared. The computational efficiency of the algorithm is clearly indicated by the fact that the time required to analyse Example 1 on a CDC7600 was 0.7 sec. The storage required with the appropriate arrays dimensioned ['or a system having 100 components and up to 125 minimal cut sets per output node is 15 k-words. These times and storagc include the ovcrall system reliability analysis.
Analysis of pesudo-reliability of a combat tank system and its optimal design. F. A. TILLMAN, C. H. LIE and C. L. HWAN(;. IEEE Trans. Reliab. R-25 (4), 239 (October 1976). The effectiveness of an actual combat tank system is analyzed. A measure of effectiveness (called pseudo-reliability) which is the reliability of a system weighted by the relativeperformance is introduced. It appears to be a more practical measure of the system effectiveness than reliability whenever the level of performance is of primary concern as is the case for the combat tank system. A model is used to optimize the design of the system in which the system pseudo-reliability is maximized subject to a cost constraint. This model involves nonlinear programming and is solved by the sequenti',d unconstrained minimization technique (SUMT). A numerical example with actual data from the test evaluation of five combat tanks illustrates the model.
~)me comparisons between redundant structures for telephone exchange central control. M. VALI-~NTI. Altd Freq. X L V (8), 510 (August 1976). Reliability prediction is of major importance in those systems which employ a realtime digital computer as a process control unit, particularly with reference to stored-program controlled telephone exchanges. This paper presents a brief outline of some redundant control systems, makes a comparison between their performance and describes the choice which, since 1971, was made at Tclcttra Laboratories in developing the central control system for time-division DTNI and AFDT1 exchanges. ALE---a carrier aircraft availability model. TIMOTHY A. Mok. IEEE Trans. Reliab. R-2fi (4), 243 (October 1976). The Avionics Logistics Effects (ALE) model was developed in 1973 in response to a US Navy requirement to evaluate potential benefits of reliability and maintainability improvements that might be incorporated into the AWG-9 weapon control system on the F-14 aircraft and AWM-23 ground support equipment. The model simulates the entire 1--14 aircraft (avionics and non-avionics) in terms of squadron flight operations, maintenance, and support aboard an aircraft carrier. Its major application is to determine the impact of avionic,'s system design and maintenance changes on aircraft availability.
Space shuttle component reuse study. CHARI.ES A. KROHN. IEEE Trans. Reliab. R-25 (4), 234 (October 1976). The effects of maximum allowable uses and mission losses on space shuttle reusable-item inventor3,, are analyzed. The approach was applied to preliminary trade-off studies of the solid rocket booster reusable components. Reuse reduces considerably the quantity of items required for 445 launches over an l 1-year period. The effect of maximum allowable uses on the total number of items to be manufactured is highly nonlinear. The effect of mission cycle reliability is approximately linear. The trade-off analysis is illustrated by the example of rocket-motor case cylinder segments. The analysis is applicable to any reusable booster component. Automatic fault diaguosLs on analogue boards. DAVID NEW'ill and DAVID DYCIIE. Electron. Emjng. p. 61 (October 1976). Diagnosis of analogue boards is not simple to implement automatically, because faults are propagated not only forwards, but backwards and sideways, making it very di(ficult to trace a fault from a failing pin. Intensive development has attacked this problem with the aim of allowing the production line operator to be completely indifferent to the type of board to be tested and diagnosed, whether it be digital, hybrid or analogue. The basis of the solution lies in defining functional blocks of circuitry, which are linked by primary paths, characterised by essentially unidirectional signal flow. While a fault may permeate a functional block it propagates from block to block only forwards towards the outputs. Faults are traced along primary paths only until the failing functional block is found.
4. M I C R O E L E C T R O N I C S - - G E N E R A L
Introduction to charge.coupled devices. J. D. E. BEYNON. Mi~roelectron. and Reliab. 15, 273 (1976). The operating principles of charge-coupled devices are described in terms of the basic properties of semiconductors. The overall aim is for those unfamiliar with CCD's to understand how they work and this to appreciate their capabilities ~LS well as their limitations. The topics discussed include charge storage and transfer, electrical and optical inputting of charge and charge sensing, factors governing maximum and mini-
mum operating frequencies, transfer efficiency, and basic CCD fabrication techniques.
Current liquid crystal display technology. W. G. FREER. Microelectron. and Reliab. 15, 315 (1976). There are two predominant types of liquid crystal display in use at present, the dynamic scattering and the twisted nematie display. In most applications the earlier dynamic scattering
17
method of moments is used to lit the distributions. A comparison of posterior producer and consumer risks in a Bayesian reliability demonstration test is made using the fitted inverted gamma and uniform distributions as the priors. There can be rather large differences in the values of the posterior risks even when the two priors fit the data equally well or equally poorly.
Several studies have been performed with the ALE model, and one in particular is discussed in this paper. In this case, Hughes recommended 27 separate reliability and maintainability improvements to the AWG-9; AWM-23 systems. The contribution of these improvements to F-14 availability is discussed, with particular emphasis on achieved crisis-flight rate.
An efficient algorithm for deducing the minimal cuts and reliability indices of a general network configuration. R. N. ALLAY, R. BH.HXroN and M. 1-. DE OLWEmA. IEEE Trans. Reliah. R-25 (4), 226 (October 1976). The paper describes an efficient algorithm for evaluating the minimal cut sets of any general network. The algorithm is based on Boolean algebra and set theory, and contains many important improvements. The four most important features are 1. only one set of topological input data is required to evaluate the minimal cuts and reliability indices of every output node; 2. a mix of undirectional and multi ended components can bc included very simply; 3. any number of input nodes may be specified; 4. a new concept of overall system reliability permits different, large, and complex systems to be compared. The computational efficiency of the algorithm is clearly indicated by the fact that the time required to analyse Example 1 on a CDC7600 was 0.7 sec. The storage required with the appropriate arrays dimensioned ['or a system having 100 components and up to 125 minimal cut sets per output node is 15 k-words. These times and storagc include the ovcrall system reliability analysis.
Analysis of pesudo-reliability of a combat tank system and its optimal design. F. A. TILLMAN, C. H. LIE and C. L. HWAN(;. IEEE Trans. Reliab. R-25 (4), 239 (October 1976). The effectiveness of an actual combat tank system is analyzed. A measure of effectiveness (called pseudo-reliability) which is the reliability of a system weighted by the relativeperformance is introduced. It appears to be a more practical measure of the system effectiveness than reliability whenever the level of performance is of primary concern as is the case for the combat tank system. A model is used to optimize the design of the system in which the system pseudo-reliability is maximized subject to a cost constraint. This model involves nonlinear programming and is solved by the sequenti',d unconstrained minimization technique (SUMT). A numerical example with actual data from the test evaluation of five combat tanks illustrates the model.
~)me comparisons between redundant structures for telephone exchange central control. M. VALI-~NTI. Altd Freq. X L V (8), 510 (August 1976). Reliability prediction is of major importance in those systems which employ a realtime digital computer as a process control unit, particularly with reference to stored-program controlled telephone exchanges. This paper presents a brief outline of some redundant control systems, makes a comparison between their performance and describes the choice which, since 1971, was made at Tclcttra Laboratories in developing the central control system for time-division DTNI and AFDT1 exchanges. ALE---a carrier aircraft availability model. TIMOTHY A. Mok. IEEE Trans. Reliab. R-2fi (4), 243 (October 1976). The Avionics Logistics Effects (ALE) model was developed in 1973 in response to a US Navy requirement to evaluate potential benefits of reliability and maintainability improvements that might be incorporated into the AWG-9 weapon control system on the F-14 aircraft and AWM-23 ground support equipment. The model simulates the entire 1--14 aircraft (avionics and non-avionics) in terms of squadron flight operations, maintenance, and support aboard an aircraft carrier. Its major application is to determine the impact of avionic,'s system design and maintenance changes on aircraft availability.
Space shuttle component reuse study. CHARI.ES A. KROHN. IEEE Trans. Reliab. R-25 (4), 234 (October 1976). The effects of maximum allowable uses and mission losses on space shuttle reusable-item inventor3,, are analyzed. The approach was applied to preliminary trade-off studies of the solid rocket booster reusable components. Reuse reduces considerably the quantity of items required for 445 launches over an l 1-year period. The effect of maximum allowable uses on the total number of items to be manufactured is highly nonlinear. The effect of mission cycle reliability is approximately linear. The trade-off analysis is illustrated by the example of rocket-motor case cylinder segments. The analysis is applicable to any reusable booster component. Automatic fault diaguosLs on analogue boards. DAVID NEW'ill and DAVID DYCIIE. Electron. Emjng. p. 61 (October 1976). Diagnosis of analogue boards is not simple to implement automatically, because faults are propagated not only forwards, but backwards and sideways, making it very di(ficult to trace a fault from a failing pin. Intensive development has attacked this problem with the aim of allowing the production line operator to be completely indifferent to the type of board to be tested and diagnosed, whether it be digital, hybrid or analogue. The basis of the solution lies in defining functional blocks of circuitry, which are linked by primary paths, characterised by essentially unidirectional signal flow. While a fault may permeate a functional block it propagates from block to block only forwards towards the outputs. Faults are traced along primary paths only until the failing functional block is found.
4. M I C R O E L E C T R O N I C S - - G E N E R A L
Introduction to charge.coupled devices. J. D. E. BEYNON. Mi~roelectron. and Reliab. 15, 273 (1976). The operating principles of charge-coupled devices are described in terms of the basic properties of semiconductors. The overall aim is for those unfamiliar with CCD's to understand how they work and this to appreciate their capabilities ~LS well as their limitations. The topics discussed include charge storage and transfer, electrical and optical inputting of charge and charge sensing, factors governing maximum and mini-
mum operating frequencies, transfer efficiency, and basic CCD fabrication techniques.
Current liquid crystal display technology. W. G. FREER. Microelectron. and Reliab. 15, 315 (1976). There are two predominant types of liquid crystal display in use at present, the dynamic scattering and the twisted nematie display. In most applications the earlier dynamic scattering