Improving supply chain performance: order picking and service network design

The thesis's main objective is to develop mathematical models and algorithms for optimising two important supply chain management problems, namely the warehouse order picker routing problem and the multi-commodity network design problem. The second chapter of this thesis presents a graph reduction algorithm for solving the Travelling Salesman Problem in a planar grid graph applied in the order picking problem. The proposed algorithm applies to any other problem with a planar grid graph. In the third chapter, a more general and realistic case of order picking within modern warehouses is considered with scattered storage policies. In this chapter, a mathematical formulation is presented for the Generalized Travelling Salesman Problem and in larger instances, a Guided Local Search algorithm is proposed. The third chapter is focused on a variant of multi-modal Multi-commodity Network design problems with delivery time, hub capacities, stochastic demand and express delivery.