analysis of discrete-time machine repair problem with two removable servers under triadic policy

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 are obtained. we develop the total expected costfunction per machine per unit time and obtain the optimal operating policy and the optimalservice rate at minimum cost using quadratic ¯t search method and simulated annealingmethod. various performance measures along with numerical results to illustrate the in°uenceof various parameters on the bu®er behavior are also presented.