Modeling And Optimization On Operation Scheduling Of A Steel Plate Stacking Yard In A Shipyard

With the regulation of the world industry structure and the improvement of shipbuilding technology of our country,the proportion of shipbuilding industry of China is increasing gradually in global market.And China has become one of the most important shipbuilding centers all over the world.As the main storage place of the production materials,steel plate stacking yard is responsible for the feed,classify stacking,storage and supply of raw materials of steels,and plays an important role in making the production operation develop successfully.However,the laggard management mode and extensive operation method of steel plate stacking yard in shipbuilding firms of our country are still remained while the production requirement and the ability of shipbuilding both nave improved.Improving the level of stacking yard management and operation efficiency becomes the key problem to be solved currently.The operation of steel plate stacking yard includes warehousing operation,storing operation and pick-up operation.And the operation planning of steel plate stacking yard consists of selection of pick-up steel plate,allocation of space resource and scheduling of operation equipments.In view of different operation kinds,this paper analyzes the research status in operation management of steel plate stacking yard in home and abroad.And much more attention is paid to the pick-up operation of steel plates in this paper.After a deep analysis on the pick-up operation process of steel plate stacking yard,a multi-stage decision optimization model is constructed.The objective of the optimization model is the shortest pick-up operation time.This model is decomposed into three small models:model of steel plate selection,model of sorting the pick-up plates and model of rehandlling decision.On the basis of the work referred in the previous section,a two stage multi-level nested optimization algorithm is designed and implemented.The first stage is the optimization of pick-up operation scheme.A set of optimized pick-up steel plates is obtained based on nested genetic algorithm.The second stage is the optimization of rehandlling operation.Under the condition that the pick-up plates have been selected in the first stage,we confirm the objective positions for the rehandlling steel plates using optimization algorithm.As a result,the optimized pick-up operation plan of steel plate is gained. At last,according to the practical operation situation of shipbuilding factory,a simulated steel plate stacking yard is built.And an evaluation index of algorithm performance is proposed to test the optimization algorithm proposed forward in this paper.Compared to the pick-up plan scheme obtained from the simulated manual operation decision,we verify that the scheme generated by our algorithm can reduce the unloading operation time and improve the operation efficiency obviously.