Optimization models and methods for maritime cargo and inventory routing problems
Abstract
This thesis is part of the DOMinant II project. The DOMinant II project is a
collaboration between three Norwegian research groups within the field of
operations research. The goal of the project is to reduce the gap between the
research frontier and the needs of Norwegian and international maritime and
road-based transport industry, by developing new models and solution
algorithms for computationally challenging discrete optimization problems in
this field. As part of the project, the aim of this thesis is to develop models and
efficient and effective solution methods for realistic maritime cargo and
inventory routing problems.
This thesis consists of four papers. The papers are connected to each other in a
way to achieve the goals of the thesis and to partially cover the aims of the
DOMinant II project. The first paper provides a benchmark suite for industrial
and tramp ship routing and scheduling problems. The second paper considers a
problem that combines traditional tramp shipping with a vendor managed
inventory (VMI) service and presents a heuristic for realistic sized instances.
The effect of offering VMI services to traditional tramp shipping industry is
then analyzed. The third paper which covers a large part of the thesis’ purpose,
introduces a rich maritime inventory routing problem. In the paper, some
realistic features such as considering multiple products and a many-to-many
distribution structure make the problem very complex. A hybrid matheuristic is
developed to solve realistic instances of the problem within reasonable
computing times. The fourth paper focuses on the very well-known ALNS
algorithm which is implemented in the first paper, to investigate the role of
randomization in this algorithm by using empirical tests through statistical tools.
The results indicate that initial implementations of simple straight-forward
deterministic alternatives are immediately able to match the performance of the
randomized components.