Study Of Closed-loop Logistics Distribution And Recycling Center Site-path Optimization

Advances in technology and the rapid development of the retail industry have led to accelerated product replacement and shorter life cycles,resulting in an elevated demand for product returns and a rapid expansion of its recycling market.At the same time,globalized supply chains,unstable energy sources,rising raw material costs and inevitable environmental pollution have led to rising social concerns about economic and environmental issues.In this context,energy and materials are constantly being consumed and environmental issues are becoming increasingly serious,giving rise to strict environmental protection bills and requirements for optimal resource allocation,forcing companies to expand their existing supply chains by establishing effective recycling systems that combine forward distribution of products with reverse recycling to improve the resource utilization and operational efficiency of logistics systems while capturing the recycling value of products.Therefore,the design of a closed-loop logistics system considering the combination of forward and reverse logistics is an important issue worthy of study.In order to further improve the research of closed-loop logistics system,this thesis starts from the design of closed-loop logistics network of products,and studies the distribution center and recycling center location allocation and product path optimization to reduce the total network cost,improve logistics efficiency and enhance environmental friendliness.This thesis summarizes the research on site-path optimization of closed-loop logistics at home and abroad,analyzes the development trend of logistics networks in the context of decarbonization,considers the application scenarios of short-life electronics,and proposes a multi-objective mixed-integer linear programming model for the characteristics of cyclical changes in their demand.The model integrates the multi-cycle demand changes of products into the decision making,introduces the site-path problem integrating the simultaneous delivery and pickup operations of forward and reverse logistics,CO₂emissions of transportation,and uncertain recycling demand,and carries out the network design of closed-loop logistics to optimize the economic and environmental objectives in the closed-loop logistics network of short life-cycle electronic products.In terms of model solving,this thesis solves two single-objective mini-cases by CPLEX 12.6 to verify the feasibility of the model,and uses the NSGA-II algorithm to determine the number and location of facilities under the multi-objective model for the distribution business case of a smartphone company in China,optimizes the routes for delivering and picking up products to each retailer,and investigates through sensitivity analysis the effects of demand,recycling rate The impact of fixed facility opening cost and vehicle type on the objectives of the closed-loop logistics network was investigated through sensitivity analysis.The results show that the proposed model effectively balances the objectives of cost reduction and emission reduction,is applicable to realistic scenarios,and helps to provide a reference basis for corporate practice.This thesis provides new ideas for the problem of location-path optimization of closed-loop logistics networks for products with cyclical changes in demand.At the same time,the simultaneous delivery and pickup of goods flow patterns and the flexible location of recycling centers considered in this thesis respond to the policy requirements of energy conservation and emission reduction,and have certain theoretical and practical significance for expanding the theory and application of low-carbon chemical flow operations.