This study is concerned with the performance modeling of a fault tolerant system consisting of operating units supported by a combination of warm and cold spares. The on-line as well as warm standby units are subject to failures and are send for the repair to a repair facility having single repairman which is prone to failure. If the failed unit is not detected, the system enters into an unsafe...

this paper analyzes a controllable discrete-time machine repair problem withl operating machines and two repairmen. the number of working servers can be adjusteddepending on the number of failed machines in the system one at a time at machine's failure orat service completion epochs. analytical closed-form solutions of the stationary probabilities ofthe number of failed machines in the sys...

  A novel optimal single machine replacement policy using a single as well as a two-stage decision making process is proposed based on the quality of items produced. In a stage of this policy, if the number of defective items in a sample of produced items is more than an upper threshold, the machine is replaced. However, the machine is not replaced if the number of defective items is less than ...

In this paper, the single machine replacement problem is being modeled into the frameworks of stochastic dynamic programming and control threshold policy, where some properties of the optimal values of the control thresholds are derived. Using these properties and by minimizing a cost function, the optimal values of two control thresholds for the time between productions of two successive nonco...

In this paper, we consider a queueing model for machine repairing system with Bernoulli vacation schedule. The failure times, repair times and vacation times are all assumed to be exponentially distributed. In congestion, the server may increase the repair rate with pressure coefficient  to reduce the queue length. We assume that the server begins the working vacation when the system is empty....

In this paper, we discuss a batch arrival bulk service queue with rework for the faculty item, possibility of breakdown, repair, and two kinds multiple vacation different threshold policy. The server serves remaining after repair completion. This type queuing model has lot applications in manufacturing/ production industries. Performance measures stability conditions are obtained. Numerical ill...

this paper studies an m/g/1 repairable queueing system with multiple vacations and n-policy, in which the service station is subject to occasional random breakdowns. when the service station breaks down, it is repaired by a repair facility. moreover, the repair facility may fail during the repair period of the service station. the failed repair facility resumes repair after completion of its re...

this paper investigates a discrete-time impatient customer queue with bernoulli-schedule vacation interruption. the  vacation times and the service times during regular busy period and during working vacation period are assumed to follow geometric distribution. we obtain the steady-state probabilities at arbitrary and outside observer's observation epochs using recursive technique. cost an...

This paper deals with the optimal control policy of two-phase service M X / Ek /1 queues with vacation, N-policy, server break downs and balking. Generating functions method is used to derive the system characteristics. The total expected cost function is developed to determine the optimal threshold of N at a minimum cost. Numerical experiment is performed to validate the analytical results. Th...