On Approximate Queueing Models of Dynamic Job Shops

In this paper we consider a class of job shops with a dispatch area and a machine shop, where operational controls are exercised at the dispatch area as well as at the machine shop. For such dynamic job shops with these two levels of control, there are three categories of models. They are (1) pseudo-static, (2) pure dynamic, and (3) pseudo-dynamic. In this paper approximate queueing models are developed for pure dynamic and pseudo-dynamic job shops; open queueing network models and controlled arrival single stage queueing models, respectively. The accuracy of the open queueing network models and their use are illustrated. An example indicative of the possible accuracy of the controlled arrival single stage queueing models is also given.