This paper considers a single-server retrial queue with constant retrial rate and batch arrivals, where an unreliable server may take an additional optional vacation after the first essential vacation. Customers arrive at the system according to a compound Poisson process, and they are served immediately if the server is available; otherwise, they will enter a retrial orbit and form a single wa...

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 system a...

The objective of this paper is to study the M/M/R machine repair queueing system with mixed standbys. The life-time and repair time of units are assumed to be exponentially distributed. Failed units are repaired on FCFS basis. The standbys have switching failure probability q (0≤q≤1). The repair facility of the system consists of R permanent as well as r additional removable repairmen. Due to i...

This paper presents the analysis of a continuous review perishable inventory system wherein the life time of each item follows an exponential distribution. The operating policy is (s,S) policy where the ordered items are received after a random time which follows exponential distribution. Primary arrival follows Poisson distribution and they may turnout to be posit...

In this paper, application of an evolutionary strategy to positioning a GI/M/1/N -type finite-buffer queueing system with exhaustive service and a single vacation policy is presented. The examined object is modeled by a conditional joint transform of the first busy period, the first idle time and the number of packets completely served during the first busy period. A mathematical model is defin...

This paper proposes the procedure to find out the total average cost in terms of crisp values for /M/1/BD/MV with fuzzy parameters. In which arrival rate, service rate, batch size, setup, vacation, breakdown, repair rates, and the start up ,build up, holding, setup, dormant, breakdown costs and cost for busy and vacation periods are all considered as trapezoidal fuzzy numbers. As ranking techni...

This study aimed at presenting a method for formulating optimal production, repair and replacement policies. The system was based on the production rate of defective parts and machine repairs and then was set up to optimize maintenance activities and related costs. The machine is either repaired or replaced. The machine is changed completely in the replacement process, but the productio...