Modelling And Solution For Slab Relocation Logistics Space Scheduling Problem In Hot Rolling Slab Yard

The slab-yard is used for storing the slabs produced by the processes of steel-making and casting.It provides the materials of the hot rolling.It is an important part of the hot-rolled process.To meet the need of the process of the hot-rolling,there are a lot of slabs stored in the slab yard,which are enough to satisfy the demand of the hot rolling.As the clients don't need so many slabs as before,there are many varieties of slabs now.Given the circumstances in which the degrees of the stack are very low and similar slabs are not stored in the same stack,the logistics of the slab relocation is to relocate the location of the slabs which are stored in the warehouse.This process can improve the regularity of the stacks and reduce the shuffling times of the related slabs.Reasonable storage method can improve the regularity of the stack and reduce the shuffling times when the slab need to be fed or be moved out of the warehouse.It can also improve the efficiency of the logistics.The slab relocation is based on the logistics of the slab relocation,which take the safety of the slab storage process and the regularity of the stack into consideration.It aims to relocate the locations of the slab in yard.If it works well,it can improve the regularity of the warehouse and reduce the shuffling times of the slabs with few movements of the process.So it makes sense to study the modeling and optimization method of this problem.The thesis does a lot of investigations during the study of this problem,which include:(1)The thesis formulates an integer programming model for the problem of the slab relocation logistics space scheduling problem based on the safety of the storage of the slabs.The model is to determine the locations of the slabs with the objective of minimizing the total number of the movements of the slab and maximizing the regularity of stacks.This thesis can get the best solution by CPLEX in small-scale instances.(2)Since the CPLEX can't get solutions within reasonable time when it is used to solve the large scale problems,the thesis proposes differential evolution algorithm(DE)to solve the problem.DE adopts continuous coding and decoding method according to the problem's characteristics.It uses the random method to generate the initial population.This thesis also designs mutation which is based on the method of DE/rand/1,crossover and selection step to solve the problem.To improve convergence speed and global search ability of DE,this thesis proposes an improvement strategy of adaptive mutation and crossover parameter.The thesis uses practical data and random data to ensure the improvement strategy is valid when compared with other algorithms.(3)Designing and developing hot rolling slab yard slab relocation space scheduling decision support system based on the proposed integer programming model and the DE algorithm.This system which includes functions of data downloading,area optimization,results evaluation and results uploading and so on.The system can solve this problem according to practical slabs' and stacks' information.The result can improve the regularity of the stack and efficiency of the logistics with less movements of the slabs.