Closed loop supply chain network design under uncertainty

Climate change and environmental impacts of economic activities, have forced supply chains to implement green policies and reduce environmental impacts and destruction to achieve competiete advantage. One approach to achive simultaneously to the economic and envitonmental objectives is to design closed loop supply chain networks (CLSCN) that integrate reverse logistics into their forward paths. In this paper, a bi-objective mixed integer linear programming model was developed for the CLSCN problem. The first objective is to minimize the cost function and the second objective function tries to minimize the time of transferring products from manufacturers to the distributors. Lp Metric and ε -constraint methods were utilized to solve the model. A numerical example was presented to show the applicability of the model and also sensitivity analysis was done. In this model two parameters of cost and demand are uncertain, in order to deal with uncertain parameters a robust optimization approach was utilizec. Multi objective particle swarm optimization (MOPSO) was used to solve the model in lare scales ad the solutions were compared with the solutions that obtained by exact methods. the findings of this research can help decision makers and executives to design efficient closed loop supply chains.