Combining Wang-Landau sampling algorithm and heuristics for solving the unequal-area dynamic facility layout problem

The dynamic facility layout problem (DFLP) is the problem of placing facilities in a certain plant floor for multiple stages so that facilities do not overlap and the sum of the material handling and rearrangement costs are minimized. We describe a model, where the facilities have unequal-areas and the layout for each stage is produced on the continuous plant floor. The most difficulty of solving this problem consists in the lack of a powerful optimization method. Wang-Landau (WL) sampling algorithm is an improved Monte Carlo method, and has been successfully applied to solve many optimization problems. In this paper, we combine the WL sampling algorithm and some heuristic strategies to solve the unequal-area DFLP. In the WL sampling algorithm, a vacant point strategy is applied to update layout at one stage. To prevent overlapping of facilities and reduce the empty space among facilities, a pushing strategy and a pressuring strategy are applied. We have tested the proposed algorithm on four groups of cases and the computational results show that the proposed algorithm is effective in solving the unequal-area DFLP.