Optimization of combined ship routing and inventory management in the salmon farming industry
Fish feed is the largest component of a salmon farmers production costs and lost
feed days are a large cost driver. Norways largest salmon farmer, Marine Harvest
Norway, hopes to cut costs and increase reliability of feed deliveries by starting
in-house feed production and distribution. In order to deliver feed to fish farms from
the new factory in an efficient and reliable way, they need to create cost-effective
and robust transportation plans.
The basis for this thesis is the problem of planning feed deliveries faced by Marine
Harvest Norway, hereby referred to as Marine Harvest. The goal is to provide a
model to simultaneously aid in routing of feed deliveries and inventory management.
We have further developed our Inventory Routing Problem (IRP) model from
Ivarsøy and Solhaug (2013) into three mathematical formulations. We have also
developed two frameworks for parallel branch-and-bound, in an attempt to search
through a larger part of the solution space in shorter time.
The three formulations have been tested on three various-sized test cases,
which differ in the number of fish farms considered, as well as production and
transportation capacity. The largest test case is a realistic representation of the
planning problem. Most of the parameters used are real data provided by Marine
Harvest, while we have made our own estimations when needed.
The first formulation is an arc-load formulation, similar to the one given in Ivarsøy
and Solhaug (2013). The arc-flow and multi-commodity formulations are extensions
of this, and include more detailed information about loads on board ships. Results
showed that the arc-flow model performed best for all test cases. The arc-load
model performed well for the smallest test case, while the multi-commodity model
suffers from long solution times for each branch-and-bound-node and has scaling
issues due to a large number of variables.
The parallel frameworks did not work as well as hoped. The first framework
parallelize the work of solving each branch-and-bound node, and did not manage
to find any integer solutions or good lower bounds. The second framework is more
promising, but our simple synchronous implementation only finds a marginally
better solution than the sequential run, and the solution time was not decreased
in accordance with the increased use of computing resources.
Place, publisher, year, edition, pages
Institutt for industriell økonomi og teknologiledelse , 2014. , 182 p.
IdentifiersURN: urn:nbn:no:ntnu:diva-26467Local ID: ntnudaim:11475OAI: oai:DiVA.org:ntnu-26467DiVA: diva2:747968
Tomasgard, Asgeir, ProfessorChristiansen, Marielle