Genetic algorithm to the machine repair problem with two removable servers operating under the triadic (0, Q, N, M) policy

This paper considers the controllable M/M/2 machine repair problem with L operating machines operating under the triadic (0,Q,N,M) policy. Expressions for the steady-state probabilities of the number of failed machines in the system are derived and taken in neat closed-form. We establish the total expected cost function per machine per unit time and formulate an optimization problem to find the minimum cost. The genetic algorithm (GA) is implemented to determine the optimal operating (0,Q,N,M) policy and the service rate simultaneously at the global minimum cost. Sensitivity analysis with numerical illustrations is also provided.