Research On Closed-loop Supply Chain Network Design And Transportation Optimization Problem For Dangerous Goods

In recent years,the extensive use of dangerous goods has produced a large number of dangerous wastes,seriously endangering the ecological environment and public safety.With the increasing environmental pollution and market competition,the government and many enterprises have realized the importance of the safety management and recycling of dangerous goods,which depends on the development of the dangerous goods closed-loop supply chain network.Therefore,it is necessary to study the design and operation process of dangerous goods closed-loop supply chain network.For dangerous goods enterprises,good design and operation of closed-loop supply chain network is very important for building green supply chain and sustainable supply chain.Taking the safety management and recycling of dangerous goods as the research object,this thesis studies the optimal design of dangerous goods closed-loop supply chain network and the transportation optimization in the operation process.The corresponding mathematical models are established,and the solution methods are designed according to the characteristics of the models.The main research work includes:(1)The single-period dangerous goods closed-loop supply chain network design problem under uncertain environment is studied,and a scenario-based two-stage stochastic programming model is proposed with consideration of uncertain demand and waste of customers.For the proposed model,two solution methods are designed:parallel enumeration algorithm and genetic algorithm.The validity of the model and the two solution methods are verified by numerical experiments.The results show that the parallel enumeration algorithm can achieve an approximate linear acceleration effect,and the genetic algorithm can obtain a good quality solution in a short time.Finally,sensitivity analysis of social acceptable risk criteria and reward and punishment intensity is carried out,and some management insights are is obtained for government.When formulating these two policies,the government should pay attention to the coordination of these two policies so as to achieve the desired results at the same time.(2)The multi-period dangerous goods closed-loop supply chain network design problem with facilities expansion is studied.Considering that customers'demand and waste will change with time,a mathematical optimization model with dynamic facilities expansion decision-making is established.By introducing two kinds of virtual variables and a series of constraints,the model is equivalently transformed into a mixed 0-1 linear programming model.The validity and advantages of the model are verified by numerical experiments.The results show that the dynamic design strategy with facilities expansion has advantages in saving costs and improving the average expected collection rate of dangerous wastes.(3)The dangerous goods multi-task transportation optimization with consideration of cooperative transportation is studied.Considering the scale effect of transportation costs,the overlapping effect of transportation risks and the requirement of delivery time,a mathematical model is established to minimize both transportation costs and transportation risks,which can rationally plan the transportation routes and confluence choices for each task.To solve this problem,a heuristic algorithm based on greedy strategy is designed.The validity of the model and the algorithm is verified by numerical experiments.The results show that different preference coefficients correspond to different transportation costs and risks,and decision makers can choose the most suitable transportation scheme for dangerous goods.(4)The multi-period hazardous goods collection planning problem with delay collection is studied.A new multi-objective mathematical model is proposed,which includes three objectives:minimizing total cost,minimizing transportation risk,and maximizing risk stability.By introducing a class of auxiliary variables and a series of constraints,the proposed model is transformed into a mixed 0-1 linear programming model.The applicability and validity of the model are verified by numerical experiments.The results show that,compared to the case without considering the objective of risk stability,considering the objective of risk stability may increase the total cost to some extent,but it can reduce the transportation risk,the uneven distribution of transportation risk in each period and the number of vehicles used.The research results obtained in this thesis can provide a theoretical basis for the scientific decision-making of government departments,and play a guiding role in the design of closed-loop supply chain network and transportation optimization for hazardous goods enterprises.