Optimal configurations of general job shops

In this paper we study the problem of minimizing the expected number of job s in a single class general open queueing network model of a job shop. This problem was originally posed by Buzacott and Shanthikumar [2] and solved b y them for a special case. We extend their work in this paper. We derive fe asibility conditions that simplify the analysis of the problem. We show tha t the optimal configuration can be completely characterized when both the u tilizations of the machine centers are high and there are a large number of servers at each machine center. We also derive conditions under which the optimization problem reduces to solving a concave or a convex program and p rovide conditions under which the uniform flow line and the symmetric job s hop (or variants of these) are optimal configurations for the job shop.