Research On Double Flexible Flow Shop Scheduling And Its Integration With Transportation Scheduling

With the rapid development of economy,both of products and demand of customers have shown the tendency of diversification.In the meantime,in order to satisfy the requirements of production and customers,manufacturing enterprises are expanding their production scale and how to maximize economic benefits through rational allocation of resources in the production system is a problem with which they are confronted.Production scheduling is a kind of optimization problem of how to make full use of varied production resources by allocating them reasonably in order to meet certain indexes.The problem of double flexible flow shop scheduling with machine selection flexibility and worker selection flexibility is more consistent with the characteristics of actual production,and the integrated production and transportation problem,as an extension problem of production scheduling,will affect the economy benefits of enterprises.Therefore,the further study on double flexible flow shop scheduling and its transportation scheduling not only has theoretical significance,but also plays a role of guiding actual production process of the products,which has important practical application value.The main contents and creations are as follows:(1)Based on the flexible flow shop scheduling problem,a double flexible flow shop scheduling problem with machine and worker selection flexibility,which exists in the actual production process,is proposed.It is described in detail and its mathematical model is established in this paper.(2)In view of the characteristics of the double flexible flow shop scheduling problem,the classical NSGAII is improved and a layer-based coding is proposed to describe the problem.Then the crossover operator and mutation operator are designed based on the work layer,machine layer and worker layer respectively.Additionally,inspired by different priority of machine constraint and worker constraint conditions,the local search operator based on two critical paths is innovatively added to the algorithm to improve the local search ability.The results show that the improved algorithm is effective for the double flexible flow shop scheduling problem,and the superior overall quality of the obtained solution set to that of the comparison algorithms proves better performance of the improved algorithm.(3)In this paper,the integrated problem of production and transportation scheduling problem,which is an extension of double flexible flow shop scheduling problem,is analyzed first,and several different production strategies and transportation strategies are designed for the production and transportation stages respectively.Based on NSGAII,each benchmark is calculated under different strategy combination conditions.Then the results are analyzed,with stability of the different strategy combination in the optimization process and quality of the Pareto optimal solution set taken into consideration,the best strategy combination for the problem is obtained.Finally,based on the best strategy combination,a scheduling scheme to a problem is given and illustrated.