A Parallel Tabu Search Algorithm for Short-term Lot Sizing and Scheduling in Flexible Flow Line Environments1

In this paper, the problem of short-term production planning in flexible flow lines is considered. A MIP model formulation of the proportional lot sizing problem for multilevel production processes with alternatively usable machines is presented. This model is very general in terms of material routing through the system and allocation of items and machines to production stages. By definition of additional constraints for the parameters a similar model for the proportional lot sizing problem in flexible flow lines is derived. For the solution of this model a parallel tabu search algorithm is presented. We describe the implementation of this algorithm by the aid of ”Virtual Data Space” (VDS) – a C-library which supports various paradigms of parallel programming and provides sophisticated load balancing methods for irregular structured applications. Experimental results measured on a parallel system with up to 192 Pentium II processors show that the new algorithm is an efficient method to compute good solutions for the presented problem, even then if problem instances are considered which are not only toy examples.