The MILP model was first validated by solving a series of small instances deriving from a real-world case study faced by a multi-national shipping company operating a fleet of multi-parcel chemical tankers.
The results obtained were compared with others presented by two authors from the literature.
Comparison between results reveals that the general precedence based model has a better computational performance than the time-slots based model proposed to solve the same problem instances.
Despite this, the exact approach has not converged and the MIP solver terminated because the memory capacity was exceeded when the full problem, involving 10 ships, 36 ports,and 79 potential cargos, is considered. After that, the iterative algorithm was applied to solve the same full problem instance.
A convergence to a near-optimal solution was achieved in only 764 second of CPU time.
Such computational performance significantly overcomes these ones achieved by other algorithms presented in the literature.
Moreover, the new schedule improves profits by approximately 40% with regards to actually used by the company.
The MILP model was first validated by solving a series of small instances deriving from a real-world case study faced by a multi-national shipping company operating a fleet of multi-parcel chemical tankers. The results obtained were compared with others presented by two authors from the literature.Comparison between results reveals that the general precedence based model has a better computational performance than the time-slots based model proposed to solve the same problem instances. Despite this, the exact approach has not converged and the MIP solver terminated because the memory capacity was exceeded when the full problem, involving 10 ships, 36 ports,and 79 potential cargos, is considered. After that, the iterative algorithm was applied to solve the same full problem instance. A convergence to a near-optimal solution was achieved in only 764 second of CPU time. Such computational performance significantly overcomes these ones achieved by other algorithms presented in the literature. Moreover, the new schedule improves profits by approximately 40% with regards to actually used by the company.
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