The Optimization Of Hybrid Flowshop Scheduling Problem In Steelmaking-continuous Casting Process Based On Fruit Fly Algorithm

The steelmaking-continuous casting process is one of the key stages in the whole steel prouction,playing an important role in the steel industry.The optimization of steelmaking-continuous casting scheduling is meaningful for improving the quality and capacity of the steel,reducing the resource energy consumption,saving the cost of production.The scheduling of steelmaking-continuous casting is characterized with diversity scheduling types,complex constraints,various processing technology and frequnent disturbance.Hybird Flowshop Scheduling is a kind of steelmaking-continuious casting scheduling types.Hybird flowshop scheduling problem(HFSP),as a kind of real-world scheduling problem,is developed on the basis of classic flowshop scheduling problem(FSP).The scheduling model abstrsacted from HFSP is the core part of the management and controling in the real-word production.And now,it has been used in the electronic industry,paper industry,textile and other fields,widely.Compared with the classic FSP,HFSP is characteristiced with multi-stages,multi-jobs and parallel machines.Each job can select anyone of the parallel machines to be processed.The mode of production is more confirmed to the real production situation.It has been proved that the HFSP which has only two stages that one of the stages has parallel machines is NP-hard problem.The HFS scheduling in steelmaking-continuous casting is also the NP-hard problem.Considering HFS scheduling in steelmaking-continuious casting,researching contents in the thesis are shown below:(1)The characteristics and difficulties are analysised based on the researching background and status.It also emphasizes the importance of optimization for steelmaking scheduling.(2)The thesis analysises the complexity of establishing mathematical modle by introducing the production and technological constraints.Considering the factors of establishing mathematical modle,3 modles are set up.The objectives are minimizing the penalty,minimizing the average sojourn times and minimizing the total flow times,respectively.(3)A novel intelligent optimization algorithm,called fruit fly optimization(FFO)algorithm is proposed.It proves that FFO algorithm can be used to solve optimization problems through the testing of standard functions.Considering the lack of the FFO algorithm,an improved fruit fly optimization(IFFO)algorithm based on improving the searching radius is proposed.And it has been proved that IFFO is better than FFO in solving problems.The comparison between IFFO and GA is also done in order to show the superiority of IFFO.Based on the results of solving the standard functions,it shows that IFFO is more effective than GA.(4)FFO algorithm and GA are used to solve mathematical modles,according to the practical situations of the iron and steel production in Baosteel complex.During the design of FFO algorithm,heuristic algorithm and special neighborhood structure are used.The experimental results show that the optimization precision and speed of FFO algorithm are better than genetic algorithm in the optimization of HFS scheduling problem in steelmaking-continuous casting.