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Availability analysis of 3-state systems
World Abstracts on Microelectronics and Reliability progressively less with the Shooman, and Jelinski-Moranda models. Simulation shows that, with respect to the number of detected errors, (1) testing the functions of a software system in a random or round-robin order gives linearly decaying system-error rates, (2) testing each function exhaustively one at a time gives flat system-error rates, (3) testing different functions at widely different frequencies gives exponentially decaying system-error rates, and (4) testing strategies which result in linear decaying error rates tend to require the fewest tests to detect a given number of errors.
Undersea transmission-system reliability with laser-diode standby-redundant optical repeaters. KAZUO AIDA and MASArd AMEMIYA.IEEE Trans. Reliab. R-33 (5) 439 (1984). This paper presents reliability evaluation formulae for a system having a series of replaceable standby, redundancy units. By using this formula, this paper evaluates the reliability of an undersea transmission system with laser-diode redundant repeaters.
A conditional probability approach to reliability with common-cause failures. JOHN YUAN.IEEE Trans. Reliab. R34 (1) 38 (1985). This paper presents a conditional probability method to evaluate the reliability or availability of a system whose components failures can be s-independent or have a common-cause. Different failure types can be in each cut-set. By applying pivotal decomposition, the chain rule of conditional probability, and the recursive rule of probability of a union of events, I obtain the steady-state system unavailability. This approach requires the failure and repair rates of each component due to s-independent causes, the occurrence rate of each common-cause failure, and the mean duration of each corqmon-cause. Hence it is practical and useful. The general model in the adverse environment assumes sdependency and faces the dilemma of how to estimate the transition rates of each component. Availability analysis of 3-state systems. NASIR M. KHAN and AsrtoK GUr'TA. IEEE Trans. Reliab. R-34 (1) 86 (1985). This paper introduces the concept of a pending-failure state in order to consider usual operating and wearout periods of engineering systems and proposes a 3-state system model. System reliability is evaluated in terms of mean time-tofailure (MTTF) and the ratio of"transition rate from pending failure to failed" to "that from good to pending failure state". The analysis is rather general and applies to many systems, regardless of mean duration of pending-failure state. The reliability and availability of this system are higher than a 2state system model having same MTTF and repair rate.
Optimal consecutive-2-out-of-n:F
component sequencing.
DAVID M. MALON.IEEE Trans. Reliab. R-33 (5) 414 (1984). A consecutive-k-out-of-n:F system is an ordered linear arrangement of n components that fails if and only if at least k consecutive components fail. When the components are not necessarily equally likely to fail, the problem of interest is to assign components to positions in the system in a way that minimizes the probability of system failure. This paper shows that when k = 2 and component failures are s-independent, the optimal configuration can be determined without knowledge of the exact particular component-failure probabilities, but with knowledge of the component ranks (in terms of failure probability).
Using the decomposition tree for directed-network reliability computation. JANEN. HAGSTROM.IEEE Trans. Reliab. R-33 (5) 390 (1984). A related paper provides an algorithm to compute the reliability of an undirected network. The algorithm exploits the decomposition tree of the network derived from decomposing the network graph into its triconnected components. This paper extends the algorithm to apply to reliability problems involving directed networks.
785
Details are presented which specialize the algorithm to apply to the problems of 2-terminal communication, transportation flow feasibility, and path-length feasibility.
Confidence intervals for system failure rates; a literature review. WILLIAM E. JUDNICK. Proc. a. Reliab. Maintainab. Syrup. 444 (1985). Reliability engineers need to be able to make statistical statements concerning an entire system's probability of failing. A point estimate for the probability of system failure may not be sufficient. Some sort of 'confidence" statements about that probability may be most desirable. However, sometimes only raw data on failure probabilities of components are available, or probabilities are estimated at various levels of confidence. Further, available estimates are sometimes founded on differing assumptions. This paper reviews the literature on this problem, focusing on why the problem is difficult, guiding the reader to the major results, and recommending an approximate method for those who would like an intuitive grasp of the subject.
Hybrid reliability modeling of fault-tolerant computer systems. KISHOR TR1VEDI, JOANNE BECHTA DUGAN, ROBERT GEIST and MARKSMOTHERMAN.Comput. Electrical Engn# I 1 (2/3), 87 (1984). Current technology allows sufficient redundancy in fault-tolerant computer systems to insure that the failure probability due to exhaustion of spares is low. Consequently, the major cause of failure is the inability to correctly detect, isolate, and reconfigure when faults are present. Reliability estimation tools must be flexible enough to accurately model this critical fault-handling behaviour and yet remain computationally tractable. This paper discusses reliability modeling techniques based on a behavioral decomposition that provides tractability by separating the reliability model along temporal lines into nearly disjoint faultoccurrence and fault-handling submodels. An extended stochastic Petri net (ESPN) model provides the needed flexibility for representing the fault-handling behavior, while a nonhomogeneous Markov chain accounts for the possibly non-Poissoon fault-occurrence behavior. Since the submodels are separate, the ESPN submodel, in which all time constants are of the same order of magnitude, can be simulated. The non homogeneous Markov chain is solved analytically, and the result is a hybrid model. The method of coverage factors, used to combine the submodels, is generalized to more accurately reflect the fault-handling effectiveness within the fault-occurrence model. However, due to approximations made in the aggregation of the two submodels and inaccurate estimation of component failure rates and other model parameters, errors can still arise in the subsequent reliability predictions. The accuracy of the model predictions is evaluated analytically, and error bounds on the system reliability are produced. These modeling techniques have been implemented in the HARP (hybrid automated reliability predictor) program. Optimal age-replacement policy for equipment monitored by a stochastically failing indicator. B. K. Yoo and C. S. SUNG. IEEE Trans. Reliab. R-34 (2) 162 (1985). An optimal agereplacement policy is presented for the system composed of a single piece of equipment and an indicator. The state of the equipment (good or failed) is monitored by the indicator, and both the equipment and the indicator can fail. Our model generalizes one of Barlow & Hunter, in that it duplicates their model when the indicator is perfect.
Fault diagnosis of analog circuits. JOHNW. BANDLERand ALYE. SALAMA.Proc. IEEE 73 (8) 1279 (1985). In this paper, various fault location techniques in analog networks are described and compared. The emphasis is on the more recent developments in the subject. Four main approaches for fault location are addressed, examined, and illustrated using simple network examples. In particular, we consider the fault dictionary approach, the parameter identification approach, the
Undersea transmission-system reliability with laser-diode standby-redundant optical repeaters. KAZUO AIDA and MASArd AMEMIYA.IEEE Trans. Reliab. R-33 (5) 439 (1984). This paper presents reliability evaluation formulae for a system having a series of replaceable standby, redundancy units. By using this formula, this paper evaluates the reliability of an undersea transmission system with laser-diode redundant repeaters.
A conditional probability approach to reliability with common-cause failures. JOHN YUAN.IEEE Trans. Reliab. R34 (1) 38 (1985). This paper presents a conditional probability method to evaluate the reliability or availability of a system whose components failures can be s-independent or have a common-cause. Different failure types can be in each cut-set. By applying pivotal decomposition, the chain rule of conditional probability, and the recursive rule of probability of a union of events, I obtain the steady-state system unavailability. This approach requires the failure and repair rates of each component due to s-independent causes, the occurrence rate of each common-cause failure, and the mean duration of each corqmon-cause. Hence it is practical and useful. The general model in the adverse environment assumes sdependency and faces the dilemma of how to estimate the transition rates of each component. Availability analysis of 3-state systems. NASIR M. KHAN and AsrtoK GUr'TA. IEEE Trans. Reliab. R-34 (1) 86 (1985). This paper introduces the concept of a pending-failure state in order to consider usual operating and wearout periods of engineering systems and proposes a 3-state system model. System reliability is evaluated in terms of mean time-tofailure (MTTF) and the ratio of"transition rate from pending failure to failed" to "that from good to pending failure state". The analysis is rather general and applies to many systems, regardless of mean duration of pending-failure state. The reliability and availability of this system are higher than a 2state system model having same MTTF and repair rate.
Optimal consecutive-2-out-of-n:F
component sequencing.
DAVID M. MALON.IEEE Trans. Reliab. R-33 (5) 414 (1984). A consecutive-k-out-of-n:F system is an ordered linear arrangement of n components that fails if and only if at least k consecutive components fail. When the components are not necessarily equally likely to fail, the problem of interest is to assign components to positions in the system in a way that minimizes the probability of system failure. This paper shows that when k = 2 and component failures are s-independent, the optimal configuration can be determined without knowledge of the exact particular component-failure probabilities, but with knowledge of the component ranks (in terms of failure probability).
Using the decomposition tree for directed-network reliability computation. JANEN. HAGSTROM.IEEE Trans. Reliab. R-33 (5) 390 (1984). A related paper provides an algorithm to compute the reliability of an undirected network. The algorithm exploits the decomposition tree of the network derived from decomposing the network graph into its triconnected components. This paper extends the algorithm to apply to reliability problems involving directed networks.
785
Details are presented which specialize the algorithm to apply to the problems of 2-terminal communication, transportation flow feasibility, and path-length feasibility.
Confidence intervals for system failure rates; a literature review. WILLIAM E. JUDNICK. Proc. a. Reliab. Maintainab. Syrup. 444 (1985). Reliability engineers need to be able to make statistical statements concerning an entire system's probability of failing. A point estimate for the probability of system failure may not be sufficient. Some sort of 'confidence" statements about that probability may be most desirable. However, sometimes only raw data on failure probabilities of components are available, or probabilities are estimated at various levels of confidence. Further, available estimates are sometimes founded on differing assumptions. This paper reviews the literature on this problem, focusing on why the problem is difficult, guiding the reader to the major results, and recommending an approximate method for those who would like an intuitive grasp of the subject.
Hybrid reliability modeling of fault-tolerant computer systems. KISHOR TR1VEDI, JOANNE BECHTA DUGAN, ROBERT GEIST and MARKSMOTHERMAN.Comput. Electrical Engn# I 1 (2/3), 87 (1984). Current technology allows sufficient redundancy in fault-tolerant computer systems to insure that the failure probability due to exhaustion of spares is low. Consequently, the major cause of failure is the inability to correctly detect, isolate, and reconfigure when faults are present. Reliability estimation tools must be flexible enough to accurately model this critical fault-handling behaviour and yet remain computationally tractable. This paper discusses reliability modeling techniques based on a behavioral decomposition that provides tractability by separating the reliability model along temporal lines into nearly disjoint faultoccurrence and fault-handling submodels. An extended stochastic Petri net (ESPN) model provides the needed flexibility for representing the fault-handling behavior, while a nonhomogeneous Markov chain accounts for the possibly non-Poissoon fault-occurrence behavior. Since the submodels are separate, the ESPN submodel, in which all time constants are of the same order of magnitude, can be simulated. The non homogeneous Markov chain is solved analytically, and the result is a hybrid model. The method of coverage factors, used to combine the submodels, is generalized to more accurately reflect the fault-handling effectiveness within the fault-occurrence model. However, due to approximations made in the aggregation of the two submodels and inaccurate estimation of component failure rates and other model parameters, errors can still arise in the subsequent reliability predictions. The accuracy of the model predictions is evaluated analytically, and error bounds on the system reliability are produced. These modeling techniques have been implemented in the HARP (hybrid automated reliability predictor) program. Optimal age-replacement policy for equipment monitored by a stochastically failing indicator. B. K. Yoo and C. S. SUNG. IEEE Trans. Reliab. R-34 (2) 162 (1985). An optimal agereplacement policy is presented for the system composed of a single piece of equipment and an indicator. The state of the equipment (good or failed) is monitored by the indicator, and both the equipment and the indicator can fail. Our model generalizes one of Barlow & Hunter, in that it duplicates their model when the indicator is perfect.
Fault diagnosis of analog circuits. JOHNW. BANDLERand ALYE. SALAMA.Proc. IEEE 73 (8) 1279 (1985). In this paper, various fault location techniques in analog networks are described and compared. The emphasis is on the more recent developments in the subject. Four main approaches for fault location are addressed, examined, and illustrated using simple network examples. In particular, we consider the fault dictionary approach, the parameter identification approach, the