Modular Spatial Scheduling Modeling And Algorithm In Block Assembly Shop

Shipbuilding is an integrated industry that provides huge and heavy furnishments for shipping, ocean developing and national defence, which has great promotion to the industries related. In recent 20 years, shipbuilding industry of China has gained high-speed progress, and China has become one of the greatest countries in shipbuilding turnout in the world. But there is a huge gap between China and other powerful countries such as Japan and Korea in some key shipbuilding indexes, such as yearly DWT per worker, yearly turnover per worker and shipbuilding period. With the great economic development and the increase of market demands, However, China is still weak in shipbuilding competition especially in the traditional advantage of low human power cost. Chinese shipbuilding companies encounter cruel pressure from Japan and Korea. It is a very important for Chinese shipbuilding companies to improve existing construction mode, shorten shipbuilding period and implement modern shipbuilding mode guided by semifinished products. It is also a strategic measure for the companies to improve the competition in participating in international shipbuilding market.Modular shipbuilding is an advanced mode based on modular design and modular fabrication. Under this mode, ship design and fabrication procedure can be improved, shipbuilding period can be thus condensed obviously, the expenses of fields, equipments and fabrication per ship can be reduced greatly. Hence, capital turnover can be expedited and market competition can be improved. Through modular shipbuilding mode, hull is decomposed into many modules, modules are fabricated based on process stage and area, and hull erection in dock. In the mode, production plan and dynamic control on it is very important. To exert the advantage of modular shipbuilding, production plan must be drawn exactly, resources such as material, facilities and human must be distributed effectively, and whole production process shall be controlled dynamically.Module fabrication in assembly shop, which is on critical production path, consumes most periods and occupies large quantity of expensive facilities. This dissertation takes it as the research focus to seek optimal modular layouts and processing sequence under the constraints of technology, space and resources. A modular spatial scheduling model is established and scheduling system minimizing makespan is developed in the dissertation. Several key issues are addressed in the dissertation as follows:(1) The characteristics of module and workspace, resources distribution in the whole process, facilities utilization, and typical constraints on shipbuilding are analyzed in a mathematical method. A computer recognition method for module, workspace and typical constraints is established. This lays the mathematical foundation for developing modular spatial scheduling model.(2) On the basisi of analysis on the problem of two-dimensional projection of shipbuilding module, and by adding a dimension of time, the modular spatial scheduling problem is put forward in a three-dimensional view. A mathematical model of modular spatial scheduling in shipbuilding is established with the objective of minimizing makespan.(3) Considering the NP-hard features of modular spatial scheduling, algorithms for batch and non-batch are given according to the production styles of flow-shop and job-shop. Based on the shape features, technology features and resources constraints, several heuristic modular spatial scheduling strategies are designed. Moreover, a heuristic modular spatial scheduling algorithm is developed using the above strategies.(4) Condidering that modular spatial scheduling is complex and diverse, such that many objectives should be satisfied such as on-time delivery, minimizing makespan, minimizing maximal tardy and improving facilities utilization ratio and so on, a multi-objective modular spatial scheduling algorithm is proposed with the objective of minimizing makespan and on-time delivery.(5) Modular spatial scheduling system in shipbuilding is established and exemplified with real data from a shipyard. The proposed algorithm is compared with grid algorithm, genetic algorithm, Cplex and manual methods. The result shows that the algorithm has comprehensive advantages in makespan, space utilization, computation time and solving large quantity modular scheduling issue.Ships are very large products and manufactured under make-to-order mode. The modular spatial scheduling algorithm developed in this dissertation can be extended to other similar heavy equipment manufacturing industries such as rockets and airplanes. The scheduling algorithms proposed in this dissettation can be made as references for improving production scheduling and manufacturing efficiency of such manufacturing industries.