Presenting a Comprehensive Multi-Objective Model of the Multi level – Multi Product Green Closed-Loop Supply Chain with a Weighted Sum Method Approach: Pareto Front Generation (Case Study: Shahpar Momtaz Shoes Co.)

Planning and inventory control are considered the main factors affecting multi-level closed loop supply chain processes in the process of returning product from consumers to manufacturers. The integrated network is called a Green Closed-Loop Supply Chain (GCLSC). By introducing a mathematical multi-objective model for linear mixed-integer programming and optimizing it through appropriate technical, engineering and management methods, this research aims to eliminate or control the workplace pathogens with a view to minimizing the employees’ limit of exposure and total cost. Thus, a set of criteria titled “Occupational Exposure Limits” are defined to ensure the safety of the workforce in all production centers. Based on the concept of the Pareto Front, a multi-objective algorithm is proposed which uses the proposed mechanism of variable weight in the weighted-sum method to change the direction in the objective space. Comparison of the performance of the algorithm based on the objective functions: minimizing both the emission of hazardous chemical substances and the costs in the workplace, demonstrates the proper performance of the weighted sum method in solving production planning and inventory control issues. The results show that staff exposure to chemical agents is within the permissible range, so that other costs are kept to a minimum.