Ph.D. Defense Sangmin Lee

Title: Approximate Dynamic Programming for Maritime Optimisation

From Liner Shipping Network Design to Empty ContainerRepositioning

Abstract:

This thesis explores the use of approximate dynamic programming (ADP) to address scalability and uncertainty in maritime logistics, through three studies at different decision levels: strategic (liner shipping network design), operational (inland empty container inventory), and tactical (global empty container repositioning).

 

The first study models the liner shipping network design problem using a Markov decision process (MDP) that co-optimizes network structure and commodity routing. Despite generating optimal solutions for small cases, ADP struggles with the problem’s high-dimensional, discrete nature, limiting its strategic applicability.

 

Shifting focus, the second study applies ADP to single-depot empty container inventory management. Using an MDP with multi-modal transport and stochastic inflows, a backward ADP algorithm improves inventory control and cost efficiency. Results highlight the value of incorporating uncertainty and transport flexibility.

 

The final study addresses global empty container repositioning via a multi-stage stochastic program using stochastic dual dynamic programming (SDDP). A case study shows that SDDP dynamically adjusts its policy to fluctuating demand and varying penalty cost structures, leveraging its ability to learn from data.

 

Overall, this thesis advances the understanding and application of ADP in maritime logistics. While ADP shows promise in tackling sequential decision-

making problems such as ECR, its application to strategic problems like the LSNDP remains challenging due to the dimensionality and complexity of the problem.

 

University supervisor: Trine Krogh Boomsma
Industrial supervisor: Klaus Kähler Holst, Niels-Christian Fink Bagger

Assessment Committee: 

Chair/Associate Professor,  Giovanni Pantuso - Department of Mathematical Sciences

Ass. Professor and Founder, Rune Møller Jensen Owner, CEO of Sealytix,

Professor, Kevin Tierney, Bielefeld University