An application of PSO in a two-warehouse inventory model for deteriorating item under permissible delay in payment with different inventory policies

This paper deals with an alternative approach for a two-warehouse inventory model for single deteriorating item considering allowable delay in payments with two separate warehouses having different preserving facilities. Partially backlogged shortages are allowed with a rate dependent on the duration of waiting time up to the arrival of next lot. Here, two different types of inventory policies, viz. inventory follows shortage (IFS) and shortage follows inventory (SFI) have been considered. To formulate the model, different realistic scenarios and sub scenarios in each policy have been investigated. The corresponding problems have been formulated as non-linear constrained optimization problems and solved by different versions of PSO algorithm. Then, to illustrate the model as well as to test the performance of the PSO algorithm, four numerical examples have been solved and the computational results have been compared. Finally, to study the effect of changes of different parameters, sensitivity analyses have been carried out by changing one parameter at a time and keeping the others at their original values.