Coral reefs optimization for unequal area facility layout with slicing tree structure

Facility layout problem (FLP) is an optimization problem of placing given facilities in a specific space to minimize overall logistics transportation cost or maximize its efficiency. Unequal area FLP (UA-FLP) means the layout design problem in that each facility has a different area. This study provides the performance of the modified coral reefs optimization on UA-FLP through experiments. Coral reefs optimization (CRO) is relatively new, and few studies have applied this method to layout design. There are two ways of placing facilities. One is flexible bay structure (FBS) and the other is slicing tree structure (STS). STS is known as a more difficult method than FBS. There have been no studies combining coral reefs optimization with slicing tree structure. By applying levy-flight to coral reefs optimization, it can easily escape from the local minima, and by applying an iterated local search method, the solution has been easily strengthened. We experimented with cases taken from previous literature and compared the results with either the optimal or best-known solutions from those studies. As a result, the problems of 7, 8, 9, 12, 20, 30 facilities were effectively addressed, and especially, AB20 and SC30 were found to have a better objective function value than previous studies.