Electronic Waste Disassembly Line Balancing Problem Optimization Model And Method

The continuous progress of science and technology and the rapid development of economy and society promote the technological innovation of electrical and electronic equipment.With the increase of the replacement speed of electrical and electronic equipment,the quantity of electronic waste is in the stage of explosive growth.The treatment of electronic waste is a global problem,because it contains toxic and harmful substances,direct incineration and landfill will cause serious harm to the environment.At present,the effective treatment method is to carry out environmental protection treatment when dismantling toxic and harmful parts to avoid environmental pollution.At the same time,the valuable and needed parts are disassembled and recycled to reduce manufacturing costs and improve resource utilization.Disassembly line is the best configuration for large-scale disassembly.The key to improve the efficiency of disassembly line and the economic benefit of enterprise lies in how to determine the reasonable order and distribution of disassembly tasks in each workstation to achieve the balance of disassembly line.Therefore,the disassembly line balancing problem(DLBP)of ewaste has important theoretical value and practical significance.In this thesis,the disassembly characteristics of electronic waste are deeply explored,such as environmental protection requirements,various types,huge quantities,high potential value,and great harm of parts and components.Combined with the current situation of enterprise disassembly,considering from three perspectives that the uncertain disassembly time of single product,multiple worker operation mode in single workstation of single product and multi product mixed disassembly mode,this thesis study the robust optimization problem of DLBP under single worker operation mode in single workstation for single product,the multi-manned complete DLBP and partial DLBP for single product,and mix-model DLBP with the two sided layout.In the process of dismantling electronic waste,due to uncertain product quality and different proficiency of operators,the operation time of disassembly task is uncertain.In order to solve the DLBP with uncertain disassembly time under single operation mode in single workstation for single product,the uncertainty set of cardinal number in robust optimization is used to describe the uncertainty of disassembly time,and a series of tasks are assigned to the workstation to maximize the profit of disassembly line.The problem is expressed as a nonlinear robust integer programming and then transformed into an equivalent linear programming.Because of the difficulty in solving this kind of problem,the exact algorithm is only suitable for small-scale cases.An improved migratory bird optimization algorithm(IMBO)is designed to solve the problem.The algorithm proposes two enhancement techniques.The first technique is to find out the optimal number of tasks to be disassembled in each sequence,rather than the random selection used in literature;the second is to construct effective neighborhood by using specific problem structure.Numerical results show that,compared with CPLEX algorithm and improved gravity search algorithm,this algorithm has strong performance,especially for large-scale problems.In addition,the example test shows that the enhancement produced by the proposed technology is obvious.In view of large-scale electronic waste dismantling,reasonably increasing the number of workstation workers can shorten the disassembly line length and product disassembly time,and improve the work efficiency of the workstation.In view of this,for the single product disassembly,the multi-manned complete DLBP problem is proposed.Aiming at minimizing the number of workstations,minimizing the number of workers,minimizing the idle time of disassembly line,and dismantling harmful parts and components with demand as soon as possible,a complete DLBP optimization model is constructed based on the priority constraints of task allocation of different workstations and different workers in the same workstation,and an improved genetic algorithm(IGA)is designed to solve the problem.Based on the global search of genetic algorithm,Metropolis criterion is introduced to improve the optimization ability of the algorithm.Numerical experiments on different scales show the effectiveness of the proposed algorithm for solving the complete DLBP problem.The optimal disassembly scheme can make the workstation allocate more disassembly tasks,effectively balance the workload of each workstation,and improve the production capacity and efficiency of the disassembly line.For the electronic waste,it is not necessary to disassemble parts which have no economic value and have no impact on the environment.Because the goal of the enterprise is to extract the largest reusable resources in the electronic waste with the minimum cost under the requirements of environmental protection.For this reason,based on the multi-manned complete DLBP problem of single product,considering the complete disassembly of harmful parts and required parts for partial DLBP,a mixed integer programming model with minimum number of workstations and workers is established,and a memetic algorithm(MAs)with heuristic decoding strategy and effective neighborhood structure is designed to solve the problem.The effectiveness of the model is verified by numerical experiments,which shows that the performance of MAs is better.Compared with the complete DLBP disassembly scheme under the multi-manned mode,the partial DLBP schemes have shorter disassembly line length and shorter product disassembly time,which can effectively save site resources and greatly improve the efficiency of disassembly line.In the face of the reality of the diversification of electronic waste products and the variety of components,each product corresponding to a disassembly process line will cause a huge waste of resources,so it is urgent to need a mixed model disassembly line which can dismantle different products.At the same time,in the case of limited site resources and high cost of linear transformation,for electronic equipment and products with small volume,various types and low equipment demand,the disassembly line adopts the two sided layout,which can effectively improve the operation efficiency and reduce the disassembly cost.In view of this,for the mixed-model DLBP,two-sided layout is considered to reduce the length of disassembly line and improve the efficiency of disassembly line.Aiming at minimizing the number of locations,workstations and load balancing,a mixed-model two sided DLBP model is established,and a variable neighborhood empire competition algorithm is designed to solve the problem.In order to improve the quality of the solution and improve the efficiency of the algorithm,variable neighborhood search is introduced to improve the quality of the solution and improve the efficiency of the algorithm.The simulation results show that the proposed method has better accuracy and robustness than other algorithms.