Effective continuous-time formulations for scheduling shipyard block assembly system

C. A. MÉNDEZ; BASÁN, NATALIA P.; J. FAULIN; A. GARCIA DEL VALLE

Quebec

Conferencia; 23th Conference of the International Federation of Operational Research Societies; 2017

The strong global competition in the shipbuilding market forces the shipyards to focus their efforts on providing reliable products of high quality, with minimum processing and assembly times, and better utilization of critical system resources. Therefore, the development of efficient medium-term and short-term operations strategies in the assembly processes of blocks becomes a potential alternative to achieve greater competitiveness.The present work aims at finding out the optimal solution of production and assembly operations in a system of multi-stage production of ships of a shipyard while all constraints are satisfied.A ship manufacturing system, which involves a series of production and assembly processes of block and sub-block for large-scale shipbuilding is considered. Hence, two new mixed integer linear mathematical formulations (MILP) are proposed to solve the scheduling problem aiming at minimizing the total processing and assembly time of blocks and sub-blocks (makespan) in the yard: a (i) MILP model based on the continuous time-slot time batches concepts, and (ii) a MILP model based on precedence continuous-time concept.The mathematical formulation based on precedenceof continuous conception of time,requires a smaller number of decision variables and, at the same time, allowsobtaining efficient solutions to academic problems with a reasonable computational effort.Both MILP formulations were tested and computational experiences were reported for real world problems.