Research On No Waiting Flow Shop Scheduling Problem Based On Modified Whale Optimization Algorithm

No waiting flow shop scheduling problem is an important combinatorial optimization problem,which widely exists in steelmaking,food,chemical and pharmaceutical fields.The problem has been proved to be NP hard when the number of workpieces is more than or equal to 3.Therefore,many scholars have been attracted to study this issue.In recent years,Whale Optimization Algorithm(WOA)with its unique spiral nonlinear search process greatly improves its performance.However,WOA also has some problems like other heuristic algorithms,such as the convergence accuracy is not ideal,and it is easy to fall into the local optimum.In order to overcome these shortcomings,this thesis proposes a whale optimization algorithm based on complementary difference operator.At the same time,in order to further improve the efficiency of WOA in solving the no wait flow shop scheduling problem,this thesis proposes a Discrete Whale Optimization Algorithm.The main work of this thesis is as follows:1.A whale optimization algorithm based on complementary differential mutation operator is proposed.The whale optimization algorithm(WOA)is a competitive meta-inspired search algorithm to solve the function optimization problem.However,in the later stages of the iteration,WOA suffers from premature convergence because the search agent was attracted by the elite vector.In this thesis,a hybrid whale optimization algorithm based on modified differential evolution called CDE-WOA is proposed.Firstly,a novel uniform initialization strategy is employed to enhance the diversity of initial population.Secondly,the differential evolution with complementary mutation operator(CDE)is embedded in WOA to improve search accuracy and speed.Thirdly,introducing local peak avoidance strategy assist CDE-WOA to jump out local optimum.Finally,the proposed CDE-WOA are tested with 14 mathematical optimization problems.The test results illustrate that CDE-WOA has better performance than WOA,IWOA,DE,CDE,and PSO in terms of convergence speed and convergence accuracy.2.A discrete Whale Optimization Algorithm is proposed.In order to solve the problem of no waiting flow shop scheduling problem directly,this thesis is based on the idea of whale optimization algorithm,discretizes whale initialization process,linear encirclement of prey process and spiral attack process to form a discrete whale optimization algorithm.Firstly,the population initialization is completed by randomly generating the combination sequence.Secondly,the linear encircling process of whales is simulated by keeping the same part between the individual to be updated and the best individual and moving circularly other rest information from the best individual.Finally,we simulate the process of spiral encircling by moving the elements left or right.Finally,CDE-WOA and DWOA are applied to solve the waiting free flow shop scheduling problem,The simulation results show that CDE-WOA and DWOA get good performance in solving the no waiting flow shop scheduling problem,And the DWOA can get strong stability in the process of solving.