Simulation-optimization of flow lines: An LP-based bounding approach

Mathematical programming representation has been recently used to describe the behavior of discrete event systems as well as their formal properties. This paper proposes approximate mathematical programming models for the simulation-optimization of flow lines with finite buffer capacities. The approximation exploits the concept of time buffer, modeled as a constraint that put into a temporal relationship the completion times of two jobs in a sample path. The main advantage of the proposed formulation is that it preserves its linearity even when used for buffer optimization in multistage flow lines. The solution of the approximate model can be used to obtain bounds on the variables of the exact model, to reduce its feasible region and hence the computation time to find the optimal buffer allocation for the line.