Reliability analysis of a two-unit redundant system with a replaceable repair facility

This paper considers a two-unit redundant system where the repair facility is subject to failure and can be replaced by a new one when it fails. By using Markov renewal theory we obtain some reliability quantities of the system and the repair facility, respectively.     

Reliability and availability analysis of two-unit warm standby microcomputer systems with self-reset function and repair facility

Reliability and availability analysis of systems having one active unit and one warm standby unit with self-reset function and one maintenance facility is presented. Two failure models are discussed. The failure unit is repaired through self-reset or maintenance according to different failure models. The state transition diagram and equation are described. The formulae for reliability and steady-state availability are given.     

Reliability analysis of a two-unit cold standby system with a replaceable repair facility

This paper considers a two-dissimilar-unit cold standby system where the repair facility is subject to failure and can be replaced by a new one after it fails. By using Markov renewal theory, we obtain some reliability quantities of the system and the repair facility, respectively.     

CHE failure in a two-unit standby system with slow switch, repair and post repair

A mathematical model of a two-unit cold standby system with critical human errors (CHE) and slow switch is investigated. The CHE leads to complete system failure, and repair and post-repair are needed before the system can be put back into operation. Slow switch means that on failure of the operative unit the switch puts the standby unit into operation after a random time. Failure time and switchover time distributions are negative exponential whereas all the repair and post repair time distributions are general. Using a regenerative point technique, we obtain various reliability characteristics which can be used to carry out the cost-benefit analysis. In a particular case, the behaviour of the cost function is also studied graphically.     

Reliability analysis of systems with fuzzy times of structure modifications

In this paper it is considered the systems which may change structure at fixed time moments because of some reasons, such as external effect, human intervention, etc. Very often the exact time moments are unknown or uncertain. Therefore, it is presented a method to compute reliability characteristics by the precise and fuzzy time moments of the system modifications. The proposed method is accurate in results and efficient in computations.     

Analysis of a two-unit parallel redundant system with phase type failure and general repair

Explicit expressions for the Laplace transform of the reliability and availability of a general two-unit parallel redundant system are obtained. The mean time to system failure and steady state availability are deduced as special cases. Some particular cases of our result are also obtained.     

Reliability of systems with two failure modes by using structure functions

This paper deals a three-state (normal, short-mode and open-mode failures) device network that is required to control the quantity of s-t flow. If the control policy is to pass the flow or to shut off the flow, i.e. the amount of s-t flow equals one, this network system is a conventional three-state system. In order to obtain the reliability of the network system, we propose a new structure function. Some examples are presented to show that using the structure function simplifies the reliability calculation.     

Reliability analysis of two-unit warm standby system with partial failure mode and inspection time

A two-unit warm standby system is discussed, in which units are identical. Partial failure and complete failure of a unit can be detected by inspection from time to time. The inspection time follows an exponential distribution, whereas the repair and failure time follows an exponential and arbitrary distribution. Several reliability characteristics of interest to system designers and operation managers have been evaluated.     

General measures of a two-unit system

In this paper, we consider a two-unit standby system with single repair facility. The bivariate random variables (X₁, Y₁); i = 1, 2, …, n are defined as the busy and idle periods respectively of the repair facility. General measures like joint point availability and joint interval reliability are obtained using the regeneration point technique. Numerical example illustrates the results.     

Redundancy optimization problems for systems with dependent failure rates

The present study is concerned with some redundancy optimization models for “load-sharing” devices. The models considered here enable one to examine the extent to which the optimal allocation of redundancies is affected if a model based on the assumption of mutual independence of components is used in situations where there is actual “load-sharing”.     

Reliability evaluation of a two-unit unrepairable system

As one of the redundancy techniques for an unrepairable system, we suppose an unrepairable two-unit standby redundant system in which each new component for replacement is supplied by an order. We analyze the stochastic behavior of our model applying a unique modification of Markov Renewal Processes. Further, we compare an unrepairable two-unit standby redundant system with an unrepairable one-unit system. Finally, we give numerical examples of the stochastic behavior for our model.     

GERT analysis of a two-unit warm standby system with repair

A two-unit warm standby system has been modelled and analysed through GERT approach. A general concept of system utilization factor and availability curve have been introduced.     

GERT analysis of a two-unit cold standby system with repair

This paper presents a GERT (Graphical Evaluation and Review Technique) analysis of a two-unit cold standby system. The various performance characteristics of the system have been derived analytically.     

GERT analysis of a two-unit warm standby system with repair

A two-unit warm standby system has been modelled and analysed through GERT approach. A general concept of system utilization factor and availability curve has been introduced.     

Performance-related reliability measures for a repairable two-unit gracefully degrading system

The system analysed is a two-unit gracefully degrading system with repair. After each repair, the unit is tested to see if the repair meets certain predefined specifications. If it does, the unit is put to operation, otherwise it goes to post-repair. The failure-time and testing-time distributions are exponential whereas all other distributions are arbitrary. The technique of embedded SMP is employed to obtain several system performance parameters, namely, MTFF (mean time to first failure), availability, computational availability, expected number of visits to a certain state etc.     

Generalised availability measures for a two-unit intermittently used repairable system

This paper obtains generalised availability measures as defined by Baxter, J. appl. Prob.18, 227–235 (1981), for a two-unit cold stand-by intermittently used redundant repairable system. Regenerative point technique of Markov Renewal Process has been employed to obtain these measures. A particular case is also considered.     

Generalized availability measures for reparable systems with preparation time for repair

Availability measures, e.g. interval reliability and joint availability, are obtained for one-unit and two-unit cold standby reparable systems in which the failed unit undergoes inspection and waits for repair for a random time because of necessary preparation for repair. The regenerative point technique of Markov renewal processes has been used to obtain these measures.     

Reliability analysis of a two-unit parallel system with dissimilar units and general distributions

We study the reliability characteristics of a parallel system attended by a single repair facility and general failure and repair time probability distribution functions (pdf). The basic mathematical problem is the solution of a pair of simultaneous Wiener-Hopf integral equations.A formal solution procedure of the equations has been discussed in the case of unspecified characteristic functions (cf).Fairly explicit solutions are performed if at least one of the failure time pdf's has a rational cf.We compare some of the results presented in previous literature.     

Reliability and maintainability of a multicomponent series-parallel system with simultaneous failure and repair priorities

This paper considers a system consisting of two subsystems connected in series with a single repair facility. One subsystem is K-out-of-N:G system consisting of N identical units, while the other consists of M different units connected in series. The life-times of the active units depend on each other in having simultaneous failure of all the operating units and repair times are distributed quite generally. The system breaks down if more than (N?K+1) units in the parallel group are simultaneously in the failed states or if any failure occures in the series group. The availability and reliability function of the system are obtained simultaneously. Explict expressions for the steady state availability of the system and the mean time to the first system failure are obtained.     

On the first failure time of two-unit systems in two environments

Using semi-Markov processes and PH distribution, we study the first failure time of two-unit systems in two environments, and show that the first failure time distribution is a PH distribution if the repair time distribution is a PH distribution.