Research On Modeling And Solving Methods Of Workshop Layout Optimization Based On Different Configurations

The facility layout problem(FLP)is an important problem in the industrial production and service industry.According to the manufacturing demands and certain rules,to achieve the predetermined goal,the FLP focuses on the reasonable organization and arrangement of the physical location of equipment,warehouses,office departments and logistics channels in the production system and service system within a limited space.Designing a reasonable layout can effectively shorten the distance of material handling,reduce the circulation time of WIP,and also show certain flexibility when dealing with the rearrangement of the facility layout caused by changes in the production plan.It is reported that 20% to 50% of the total operating costs and 15% to 70% of the total production costs of manufacturing enterprises are related to material handling costs.As a part of production and operation strategy,FLP is often regarded as one of the most important design decisions.At the critical moment when manufacturing enterprises are accelerating the transformation and upgrading of intelligent manufacturing,considering actual development needs,it is very necessary to expand the research on the layout of new configurations and novel optimization methods under different production characteristics and modes.In theory,FLP belongs to a typical NP-hard problem,and its optimal solution cannot be obtained in polynomial time.Therefore,building a more efficient mathematical model and designing a superior optimization method is also a hot topic in the field of facility layout.Considering the new requirements of the actual production system for layout optimization,this thesis studies the facility layout of different configurations.Considering the limited layout space in the actual production layout activities,this thesis studies the optimization of the corridor layout in multi-floor space.The double-floor corridor allocation problem(DFCAP)is proposed,and a mathematical model of this problem is built.Aiming at the target of minimizing material handling costs,firstly,the improved discrete flower pollination algorithm is designed to solve it.Three methods used to generate initial population are designed for the algorithm,a variable neighborhood search structure is constructed,and the termination criterion of the algorithm is redefined.Sequentially,considering the goal of minimizing the corridor length,a genetic algorithm with variable neighborhood search based on Pareto dominance theory is designed.This algorithm is used to solve the bi-objective corridor allocation problem,and its effectiveness and superiority are shown according to the obtained results.A double-floor double row layout problem(DFDRLP)considering the position of a vertical channel is proposed.This problem studies the optimization of double-row layout in double-floor space.Aiming at minimizing the material handling cost,this problem involves assigning machines to different floors and different rows.Simultaneously,the optimization of the position of a vertical channel that connects different floors is considered.The mathematical model of this problem is established,and the symmetry-breaking constraint is designed to speed up the solution of the model.Since the DFDRLP has the mixed characteristics of combinatorial optimization and continuous optimization,a hybrid evolution algorithm based on a two-stage strategy is designed.The neighborhood search structure based on pairwise exchange and insertion operation is mixed,and mutation operation is added to ensure the exchange of neighborhood space.The comparison results with other current algorithms verify that the proposed algorithm has obvious advantages in solving speed and quality.In view of the deficiencies in the current research on the multi-row layout problem(MRLP),a new MRLP layout configuration is proposed which considers the influence of shape of machine on the layout and the minimum gap between machine and floor boundary.In order to minimize the material handling cost,the number of layout rows and the area of the layout envelope,a mathematical model is constructed.In order to facilitate the algorithm design,the representation method of the proposed MRLP solution is redesigned.A complete MRLP feasible layout can be expressed as row position vector,row space vector,machine index sequence and machine position vector.Based on this representation method,a two-stage solution method combining multi-objective discrete differential evolution and linear programming is proposed.The proposed method firstly discretizes the differential evolution formula and redefines the mutation,crossover and selection operations.Then,the effects of three evolution modes on the solution performance of the algorithm are compared through example simulation tests.From the perspective of plant layout planning,considering the collaborative optimization of layout in multiple production workshops,a multi-workshop facility layout problem(MWFLP)is proposed.This problem considers the dividing and distribution of machines in different workshops,and machines in the workshop are arranged in the form of unequal area layout.The MWFLP considers the transportation of materials inside and outside workshops respectively.Firstly,this thesis constructs a multi-objective mixed-integer linear programming model of this problem,and the optimal solutions are obtained for the small-scale problem.Then,a multi-objective particle swarm optimization algorithm is developed which designs an effective representation for MWFLP to avoid the generation of infeasible layouts.The proposed multi-objective particle swarm optimization algorithm redefines the particle velocity,position and learning mechanism,and also designs a new search framework.Finally,several unequal-area facility layout problem instances are used to test the performance of the algorithm,the comparison results show that the proposed method has more advantages than other algorithms.Based on the actual production demands,this thesis studied the layout problems of different configurations,a series of mixed-integer linear programming mathematical models were established,and a variety of intelligent optimization algorithms with obvious solution advantages were designed.This research expands the research content in the field of layout optimization,and provides rich ideas and methods for solving this kind of problems.It is of great practical significance for the actual production workshop to improve efficiency,save resources and improve economic benefits.