Research On Cold Slab Prepared Logistics Scheduling Problem In Hot-Rolling Slab Yard

The slab yard is an important buffer in iron and steel enterprise production process,connecting the steel-making process with hot rolling process.Therefore reasonable logistics scheduling in hot rolling slab yard plays a key role in the hot rolling production process.The cold slab prepared logistics,which is the most important logistics in slab yard,contains operations of picking up the required cold slabs to feeding area and assigning locations in feeding area according to the slab rolling sequence in the hot-rolling production process.When picking the required slab up,if there are some slabs covering it in the same stack,it needs to move the covering slabs to other stacks in idle area first,which is called shuffling.The cold slab prepared logistics scheduling is to determine the retrieving sequence of required slabs in hot rolling scheduling and their locations in feeding area satisfying the slab rolled sequence,and to determine the restorage space for covering slabs during shuffling process.The retrieving sequence of required slabs and the restorage space for the covering slabs influent the number of shuffles occurring in the process of cold slab prepared logistics.Reasonable cold slab prepared logistics scheduling can effectively reduce the number of shuffles and keep the stacks regular.Therefore,research on modeling and optimization method for cold slab prepared logistics scheduling problem has significance meaning for improving the logistic efficiency in the process of picking up the required cold slabs for preparing hot rolling production.Around the research on the cold slab logistics scheduling problem,the main contents include:(1)An integer programming model is formulated for the cold slab prepared logistics scheduling problem.The model contains regularity constraints of satisfying the stack security as well as the required slabs rolling sequence constraints.The objective is minimizing the total number of shuffles and the overall crane travelling distance,and maximizing regularity of stacks.This thesis adapted CPLEX to solve the small size model to prove the model validity.(2)An improved differential evolution algorithm(improved DE)based on self-adaption mutation is proposed to solve the problem,because CPLEX is unable to solve the problem in large size within valid time.Improved DE adapts continuous coding combining with the characteristics of the problem.A mixed strategy is proposed to generate initial population based on heuristics algorithm,local search algorithm and random generation.This thesis designs self-adaption mutation because of randomness of normal DE's mutation.Improved DE improves 3,15%by comparing with normal DE after experiments based on random data.Improved DE improves 10.7%by comparing with current method in the experiment of actual data.(3)The cold slab prepared logistics scheduling optimization decision support system is designed and developed based on inter programming model and improved DE on the background of iron and steel enterprise slab yard logistics.The system includes some modules such as data download,automatic optimization,manual optimization,results evaluation.Also the system can realize human-computer interaction.The system can provide decision-making support for the cold slab prepared logistics in slab yard to improve the efficiency of logistics and ensure the hot rolling production rhythm.