In the article authored by Alexander Rave, Pirmin Fontaine, and Heinrich Kuhn, we analyze the optimal distribution of medications to smaller clinics, considering both inventory costs and uncertain demand. The focus was on a two-echelon Inventory Routing Problem (IRP) with stochastic demand, modeled as a two-stage stochastic program. The study accounts for short-term replenishment orders to prevent shortages, executed by various transport means such as vans or drones. To efficiently solve larger, practically relevant instances, an Adaptive Large Neighborhood Search (ALNS) algorithm was developed, specifically optimizing routes, delivery intervals, and inventory strategies. A numerical case study at a large German clinic supplying multiple smaller clinics explored the impact of integrating drone deliveries instead of conventional vans on overall costs. Results indicate that the integrated approach achieves cost savings of 57% for the surrounding clinics and 18% for the central clinic.
The article is now available online here