The parallel stack loading problem minimizing the number of reshuffles in the retrieval stage

Abstract

In this paper, we consider the parallel stack loading problem (PSLP) with the objective to minimize the number of reshuffles in the retrieval stage. Since in the PSLP the incoming items have to be stored according to a fixed arrival sequence, some reshuffles cannot be avoided later on. We study two surrogate objective functions (number of unordered stackings, number of badly placed items) to estimate the number of reshuffles and compare them theoretically as well as in a computational study. For this purpose, MIP formulations and a simulated annealing algorithm are proposed.