Research On Combined Block Stockyard Scheduling And Flat Transporter Transportation

At present,shipbuilding mode tends to be informatization,standardization and modularization,the production scheduling of assembly block affects the shipbuilding efficiency directly.As the basic unit of ship construction,block needs to go through outfitting,painting and other techniques after leaving the manufacturing workshop,then pick up and assemble the ship at the dock.In order to coordinate the technological tempo,the stockyard is divided into cells for temporary storage and partial processing.The block is transported by flat transporters(FT),the scheduling process is limited by space and transportation resources,which makes scheduling difficult and costly.And unreasonable block scheduling method and FT allocation strategy are the main causes of traffic congestion in shipyards.Therefore,it is necessary to optimize scheduling scheme and reasonably distribute the FT,so as to reduce the cost of scheduling and improve the scheduling efficiency.The main contents of this dissertation are outlined as follows:(1)For scheduling in single stockyard,considering block grouping techniques,two blocks with suitable specifications and similar execution time can be combined and stored in one cell.The interference of combined blocks was analyzed,and the depth-first search was used to plan the route.A combined block scheduling model was built to optimize the number of obstructive blocks.A strategy based on cell's weight for allocation of blocks was proposed,and a hybrid algorithm was used for optimization to obtain the scheduling scheme.The effects of scheduling period,stockyard size and capacity on the experimental results were analyzed and verified.(2)For FT scheduling between stockyards,the constraint relationship between TFs were analyzed.Combined with FT's quantity and load capacity limits,as well as the loading and unloading time,a FT scheduling model was built considering the tardiness and delay penalties.Greedy algorithm and genetic algorithm were used to optimize the task sequence which assign to FT,and the feasibility of the solution was tested and repaired based on the constraint relation.(3)For scheduling between multi-stockyard,considering the process of blocks,the process properties of stockyards,block combination,a multistockyard scheduling model was built to minimize the total cost.A moving strategy of obstructive block based on its process stage was proposed,and the traditional task sequence strategy was improved and optimized by Tabu search.The scheduling scheme is obtained,and the effects of the occupancy rate and the combination of various scheduling strategies on the scheduling results are analyzed and verified.