Consistent Stochastic Inventory Routing Management (COSIMA)
Final Report Abstract
The project covered many variants of the Consistent Stochastic Inventory Routing Problem. It was investigated under non‐stationary demands and considering consistency aspects such as delivery time windows and delivery time consistency within given time windows. Results show that the benefit of integrated planning of lot‐sizing and routing under non‐stationary demands is less beneficial than if demands are stationary. Under non‐stationary demands, the lot‐sizing solution is dependent on peaks and lows of demands to a greater extent, such that they influence the lot‐sizing solution and allow for fewer synergies than if stationary demands are assumed. Dynamic safety stock planning is applied, to hedge against demand uncertainty and account for non‐stationarity of demands. This feature is new to the literature on inventory routing. Moreover, the IRP is investigated under intra‐day demand depletion for a planning horizon of one week, which was so far done only for a planning horizon of one period (day). For the first time in the literature, the impact of considering stockout situations due to bad delivery plans, and late deliveries, are evaluated in the framework of both deterministic and stochastic demands. Results show that the proposed algorithms outperform other methods adapted from the literature. Finally, an approximate dynamic programming algorithm to solve the stochastic dynamic variant of the problem is presented. An iterative procedure to adapt the reorder points and replenishment quantities of all customers is presented and saves more than 3 percent of total costs on average compared to the best result obtained by six other policies. The savings are achieved through the adaptation to the non‐stationary demands and the advancement of urgent replenishments.
Publications
- (2020) Matheuristic search techniques for the consistent inventory routing problem with time windows and split deliveries. Operations Research Perspectives 7 100152
Alarcon Ortega, Emilio J.; Schilde, Michael; Doerner, Karl F.
(See online at https://doi.org/10.1016/j.orp.2020.100152) - (2018). Consistent Inventory Routing with Split Deliveries. In N. Kliewer, & J. F. Ehmke, Operations Research Proceedings 2017: Selected Papers of the Annual International Conference of the German Operations Research Society (GOR), Freie Universiät Berlin, Germany, September 6‐8, 2017 (pp. 395‐401). Cham: Springer
Alarcon Ortega, E. J., Schilde, M., Doerner, K. F., & Malicki, S.
(See online at https://doi.org/10.1007/978-3-319-89920-6_53)
