Research On Dynamic Stowage Problem Of Coils-Ship Based On Differential Evolution Algorithm

The main mode of coil transportation is shipping,and quality of stowage plan has a direct impact on the efficiency of transportation.The stowage plan is to determine the specific loading position of the coil in the ship considering the factors such as the rules of how coils put on ship and coil properties.At present,the load capacity of ship is significantly increasing,then a ship usually have a number of dynamic stowage plans.In practice,planers need make many stowage plans for one ship according to the different arriving time.However,there is no research that considers the multiple stowage plans.It is difficult to take the properties of the coils which have already been loaded into account.Therefore,the loading position of coil is not centralized,which easily lead to a large number of reshuffle operations when unloading the coils.Besides,the ship is imbalance during the whole process,which reduces the transportation efficiency and increases the transportation cost.To solve above issues,this thesis studies the ship dynamic stowage plan problem of coils.This thesis mainly studies around the following three aspects:(1)In order to solve the optimization problem of ship dynamic stowage,we considers the constraints such as batches of plans,invariant of the coil position constraint,the coil loading regulation,the size of ship,the balance of ship,etc,and established a linear programming model to minimize the number of stacking in the unloading process and the crane's movement during loading.The optimal solution for small-scale problems can be obtained by CPLEX,which verifies the correctness and effectiveness of the model.(2)A classification search based heuristic algorithm and an improved differential evolution algorithm are proposed to effectively solve the ship dynamic stowage problem of coils.A mixed real number coding method is introduced for the proposed differential evolution algorithm.Four novel strategies including improved encoding,parallel differential evolution,improved mutation strategy and DE&EDA hybrid mechanism are proposed to improve the performance of the algorithm.Through solution validation by a large number of actual data and random data,the improved differential algorithm proposed in this paper performs better than the classical differential heuristic algorithm.(3)Based on the mathematic model and the proposed differential evolution algorithm,a ship stowage automatic decision support system of coils is developed.The system includes the establishment of stowage database,data management,material summary,the group ship to port,automatic stowage,and manual modification,print stowage plan and so on.It is to achieve efficient ship stowage program,and reduce business costs.