Reliability and availability analysis of an n-unit outdoor power system subject to adjustable repair facility

This paper presents a newly developed stochastic mathematical model to represent a system of n active redundant outdoor power equipment. The system considered is subject to common cause failure and adjustable repair facility. Laplace transforms of the state probabilities, system reliability and availability equations are developed. In addition, steady-state availability and mean-time-between-failures expressions are developed. The special case when n = 2 is discussed numerically.     

s̱-expected busy period of the service facility of a 1-server n-unit system subject to arbitrary failure and different repair strategies

This paper deals with the s?-expected busy period of a n-unit system with a single repair facility. The service facility is called for whenever r (1 ≤ r ≤ n) units are in failed condition and is retained until no unit is waiting for repair. The analysis is carried out under the assumption that the time to failure of a unit is arbitrarily distributed while the service rate is constant. The case when n = 2 with the failure time distribution is 2-stage Erlangian is discussed.     

An n-unit standby redundant system with r repair facilities and preventive maintenance

Identifying suitable regeneration points the availability and reliability of an n-unit warm standby system with r repair facilities, in which the operating online unit is subjected to preventive maintenance are obtained. A numerical example is provided to illustrate the results obtained. Based on the numerical result, an optimal PM policy is also derived.     

Stochastic behavior of a two-unit cold standby redundant system subject to random failure

The present paper deals with a stochastic model of a two-unit cold standby redundant system subject to random failure. The random failure occurs at random times which follow an exponential distribution. Using a regenerative point technique in the Markov-renewal process, several reliability characteristics are obtained. The mean time to system failure function is studied graphically.     

Analysis of 1-server n-unit parallel system subject to different service strategies

This paper deals with the cost-benefit analysis of 1-server n-unit parallel system subject to different service strategies. At t = 0, all the n units are switched on. The repair times of the units are arbitrarily distributed, while the failure rates of the units are constants. The system is analysed by writing integral equations for the probabilities of the system being found in various states by identifying the system at suitable regeneration epochs. These equations are solved using integral transforms. The following system characteristics, namely,

1. (1) expected duration in [0, t] k units are operating, 0 ≤ k ≤ n

2. (2) expected duration in [0, t] the server is busy with the repair of the units

3. (3) expected number of repairs in the interval [0, t], and

4. (4) expected number of times the system enters down-state

are evaluated to carry out the cost-benefit analysis of the system.     

Stochastic analysis of a two-unit cold standby system subject to maximum operation and repair time

A two-unit standby system is considered under excess time stochastic behaviour, i.e. the failure and repair time of the on line (off line) unit is exceeding some prespecified value. Whenever an operating unit crosses a prespecified operation time, it is sent to preventive maintenance and when repair of a failed unit crosses a prespecified time, the unit is rejected and replaced by a new unit. Using the regeneration point technique, certain characteristics of the system are derived and the cost of the system is calculated. Particular cases of the system are also considered.     

Profit analysis of a one-server one-unit system with partial failure subject to random inspection

This paper deals with the cost-benefit analysis of a single-server one-unit system with partial failure, which is subject to random inspection. An inspection policy model is considered in which the partial failure of the unit is detected only by inspection, but complete failure of the unit is detected instantaneously without inspection. The system is observed at suitable regenerative epochs in order to obtain several economics-related system characteristics. Explicit results are obtained in a few particular cases. Graphs are also given.