Research On Modeling And Optimization Of Dynamization And Robustness Of Row Facility Layout Problem

Facility layout problem is a kind of problem in which facilities are arranged in a specified form within a specified range according to requirements.The optimization goal is to reduce the total material handling cost during the operation of the facilities.At present,most of the existing researches on the problem focus on the static problems where the material interaction between facilities does not change with time.The changes in the logistics situation between production facilities caused by product iteration often have stage characteristics.Before the product replaced,the material flows between facilities are basically stable,which can be regarded as a static problem.When the product is iterated,the changed process flow will lead to a new inter-facility logistics situation,and the original facility layout for static problems may increase the material handling cost of the new production stage.Due to the uncertainty of the upstream and downstream supply chain or the production process itself,another kind of change in the material flow between facilities is usually more random,which also makes the facility layout plan designed according to the static logistics situation may bring about large fluctuations in the total material handling cost in the actual production process.Such fluctuations will increase the uncertainty of production,and in order to cope with this uncertainty,more redundancy needs to be left in the design of the production system,increasing the overall cost.Thus,it is an effective solution to find a more stable facility layout scheme in the case of random changes in the material flow between facilities.This type of problem is called the problem of facility layout considering robustness.This thesis studies the dynamic facility layout and the problem of facility layout considering robustness,and selects two double-row facility layout problems as representatives,which are Corridor Allocation Proplem(CAP)and Parallel-row Ordering Problem(PROP).This thesis studies and analyzes the dynamic problems and the problem considering robustness corresponding to these two facility layout problems.The obtained method is applied to practical cases,and the corresponding optimization results are given.In this paper,under the condition of dynamic environment and random fluctuation of material handling cost(MHC)between facilities,the static CAP model,dynamic CAP model,robust CAP model,static PROP model,dynamic PROP model,and robust PROP model are respectively utilized.The results confirm that for the dynamic environment and the random fluctuation MHC,the corresponding model can obtain a smaller overall cost.By utilizing the corresponding improved algorithm to solve the larger-scale dynamic problems and robustness problems,it is also confirmed that the solution obtained by the new algorithms has advantages over the solution of the static problem algorithms for the corresponding production environment.The main research contents of this thesis are as follows:(1)Mathematical models for the dynamic corridor allocation problem(DCAP)and corridor allocation problem considering the robustness(r CAP)are established.After verifying the correctness and solution performance of the models through static calculation examples,a generation method of dynamic calculation examples is constructed,and the existing calculation examples are transformed into dynamic calculation examples.The optimal solution sequences of complicate conditions are calculated by the new models.The advantages of the new models are illustrated by comparing the static and new solutions.(2)Corresponding models for the dynamic parallel row ordering problem(DPROP)and the parallel row ordering problem considering the robustness(r PROP)are respectively constructed.The correctness of the two new models is verified respectively,and then the dynamic parallel row ordering problems generated according to certain rules and the parallel row layout problems of floating material flow matrix are solved.The advantages of the two new models on their respective problems are illustrated by comparing with the static solutions.(3)For DPROP,a hybrid algorithm of harmony search and tabu search is designed to optimize large-scale problems that cannot be solved by mathematical models.The algorithm is improved for dynamic problems and complements the advantages of the two algorithms.By comparing with the existing algorithms’ ability to solve PROP,the advantages of the new algorithm are verified.The hybrid algorithm of harmony search and tabu search is utilized to solve large-scale DPROP,and the optimal solutions given is compared with the optimal solutions of the static problems,which shows that the solutions given by the new algorithm are more advantageous in large-scale problems.(4)For r CAP,a simplified two-stage meta-heuristic algorithm is proposed to optimize large-scale problems that cannot be solved by mathematical models.According to a solution rule for the row layout problem found in this thesis,the step of calling the exact solver in the original two-stage meta-heuristic algorithm is simplified,which improves the running efficiency of the algorithm.The new algorithm is utilized to solve the static problem and compared with the results of the existing algorithm,it shows that the new algorithm can reduce the number of iterations of optimizing while maintaining the solving ability.Through the new algorithm,the robustness of the solutions is considered for large-scale calculation examples,and the optimal solution sequences are obtained.The new solutions have more advantages in facing problems under the condition of floating material flow matrix.(5)In this thesis,real production lines is studied,and practical cases for optimization are obtained by collecting relevant data and processing it accordingly.By utilizing the algorithm designed in this thesis to optimize the case under static conditions,dynamic conditions and considering the robustness of the facility sequence,four types of facility layout forms for different needs are obtained.This thesis studies the solution methods of two double-row facility layout problems in the dynamic environment and the inter-facility material flow floating environment,gives the corresponding solution ideas and results,and shows the advantages of the new models and algorithms through comparison.The research on the dynamics and robustness of facility layout has positive significance for promoting the development of theoretical and applied research in the field of facility layout problems.