Modelling multi-tour inventory routing problem for deteriorating items with time windows

In the recent past, deteriorating inventory has been intensively studied. However, only a few researchers have focused on the inventory routing problem for deteriorating items. There are many items, such as food and electronic products, which deteriorate over time, and many other products in the market have perishable characteristics. The items not only decay during the stockpiling period, but also deteriorate throughout transportation time. To determine deterioration rate and time, this study develops an inventory routing problem with time windows for deteriorating items. Particle Swarm Optimization (PSO) is used to solve the problem since PSO can solve problems in a reasonable amount of time with near-optimum solutions. Two examples are used to illustrate the model. In sensitivity analysis, the parameters that impact costs are demonstrated. Our results show that the deterioration rate in inventory has larger effects than that in the vehicle; therefore, this research study makes a signicant contribution, and managers can devote more effort to reducing deterioration rate in inventory rather than the deterioration rate in vehicles.