Retrieving containers from a bay in a port terminal yard is a time consuming activity. The Block Retrieval Problem (BRTP) aims at minimizing the number of relocations, the unproductive moves of hindering containers, while retrieving target containers belonging to a customer. The choice of relocations leads to alternative bay configurations, some of which would minimize the relocations of forthcoming retrievals. The Bi-objective Block Retrieval Problem (2BRTP) includes a secondary objective, the minimization of the expected number of relocations for retrieving the containers of the next customer. This paper provides NP-Hardness proofs for both the BRTP and 2BRTP. A branch-and-bound algorithm and a linear time heuristic are developed for the BRTP; a branch-and-bound algorithm and a beam search algorithm are presented for the 2BRTP. Extensive computational tests on randomly generated instances as well as instances adapted from the literature are performed, and the results are presented.
- Management - Professor
- EPSRC Centre for Doctoral Training in Statistical Applied Mathematics (SAMBa)
- Information, Decisions & Operations - Director of Studies MSc in Business Analytics
- Bath Centre for Healthcare Innovation and Improvement
- Institute for Mathematical Innovation (IMI)
- Smart Warehousing and Logistics Systems
Person: Research & Teaching, Researcher