Crane Scheduling In Slab Yard Of Steel Enterprise

Under the integrated production model of steel-making, continuous-casting and hot-rolling, slab-yard plays the buffer role between continuous-casting and hot-rolling. The management level of slab-yard directly affects the production continuity of continuous-casting and hot-rolling as well as the production cost of the whole integrated production model. Both the transferring and shuffling of each slab are completed by a crane in the slab yard. For a crane, the idle operation is the main factor that causes the low utilization. In this thesis, a crane scheduling problem for the hot-rolling slab yard is studied. For a given set of crane tasks, the problem to decide the crane route and operation sequence of all tasks. With the purpose of improving the utilization of crane as well as lifting the efficiency of the whole slab yard minimizing the completion time of all tasks is selected as the objective of the problem. The result of research can not only improve logistics management level of the steel enterprise, but also reduce the operation cost of logistics. The main content of this thesis are summarized as follows:(1) According to the characteristics of slab yard crane scheduling process of the iron and steel enterprise, a 0-1 mixed integer linear programming model with the objective of minimizing the completion time of all tasks is built for the crane scheduling problem with the given crane task. The validity of the model has been verified by the linear solver CPLEX.(2) The crane scheduling problem under this thesis can be seen as a traveling salesman problem (TSP) which has been proved to be NP-hard, Then the Branch-and-Cut algorithm which is a efficiency exact algorithm for solving the integer NP-hard problem is adopted to solve the our problem.(3) Considering the large scale of the practical crane scheduling problem, the exact algorithm cannot be applied to practice. Hence a tabu search method is developed to solve the large scale problem appropriately. Firstly, based on the structure characteristic of the problem, a greedy heuristic is designed for obtaining the initial solution. Then two kinds of search neighborhoods with the tabu search frame are proposed to improve the initial solution. The experiment results on practical data can show that the tabu search heuristic is valid and effective for solving the crane scheduling problem.(4) Take the slab library crane of a domestic large steel enterprise as background, based on the proposed model and tabu search heuristic, a slab yard crane command decision support system is developed. The decision support system can automatically optimize the crane sequence of tasks and the crane route and dynamic simulate crane task route. The dynamic image provided by the system can help planners get more information about the crane schedule and guarantee the smooth of cranes operations. The application of system can reduce logistics cost of the slab transferring in the slab yard.