15h30 - 15h55
On Storage Assignment Policies for Unit-Load Automated Storage and Retrieval Systems.
We present a discrete-event simulator that was designed to accurately reproduce the characteristics of an industrial AS/RS owned by a large manufacturer in the food industry located in Quebec City, Canada. Various scenarios inspired by real data provided by our industrial partner were used to compare the system performance under several storage assignment policies. Our experimental results confirm our hypothesis that the system behavior deviates from the theoretical expectations as soon as the most simplistic, yet realistic conditions are considered.
15h55 - 16h20
On Sequencing Policies for Unit-Load Automated Storage and Retrieval Systems.
In this talk we review and adapt the most popular storage and sequencing policies to dynamic contexts, and then we propose a mathematical model to simultaneously solve the sequencing and storage location problems. Computational results based on a thorough simulation experiment plan confirm that having the right sequencing approach can have a measurable impact (up to 23%) on AS/RS performance. When coupled with a storage assignment policy, an integrated approach encompassing request sequencing and storage location decisions can yield a reduction of up to 45% in crane travel-time.
16h20 - 16h45
A Branch and Bound Approach to Scheduling Material Handling in Cross Docking Terminals
Cross docking is a concept that allows products to transfer directly from incoming to outgoing semi-trailers in a logistics facility. This presentation investigates the problems with scheduling semi-trailers as well as inside transfers in order to lessen double handling. It proposes an Integer programming formulation to model freight transport. Some families of valid inequalities are introduced to strengthen the formulation. Also, it describes a special branching structure and several properties to enhance the branch and bound method. Computational experiments show that this algorithm can solve most instances of up to 20 incoming semi-trailers within a reasonable time.
16h45 - 17h10
Layout and Trailer Flows Optimization in a Distribution Center Yard
Problems related to distances have been studied extensively in various industries, but not much for distribution center yard flows. Our research focuses on optimizing the layout of the yard to minimize the distances related to trailer flows. We show analytical results under various layout types using a Monte Carlo simulation.