THE OPTIMIZATION OF A MULTI-PERIOD MULTI-PRODUCT CLOSED-LOOP SUPPLY CHAIN NETWORK WITH CROSS-DOCKING DELIVERY STRATEGY

The main reason for the development of this research refers to the increased attention of businesses to the CLSC concept due to the social resp on-sibilities, strict international legislations and economic motives. Hence, this study investigates the issue of optimizing a CLSC problem involving multiple manufacturers, a hybrid cross-dock/collection center, multiple retailers and a disposal center in deterministic, multi-pro duct and multi-period contexts. The bi-objective MILP model developed here is to simultaneously minimize total costs and total processing time of CLSC. Both strategic and tactical decisions are considered in the model where retailer demands and capacity constraints are satisfied. Since the presented model is NP-hard, NSGAII and MOPSO are hired to find near-to-optimal results for practical problem sizes in polynomial time.Then, to increase the accuracy of solutions by tuning the algorithms' pa-rameters, the Taguchi method is applied. The practicality of the developed model and the efficiency of the proposed algorithms are demonstrated using a set of real-sized problems. Furthermore, sensitivity analysis is conducted to study the effects of variations in demand, on the objective function values. Finally, the results are examined by the statistical analysis and performance measures which indicates the better performance of MOPSO in comparison with NSGAII in general.