عنوان مقاله [English]
This paper develops a model that aims to plan transportation and inventory in a multi-product multi-period supply chain, in which one supplier meets the needs of a group of retailers. The developed model attempts to coordinate the different members of the supply chain whilst taking carbon emissions into consideration. Vehicles used for transportation are considered to be heterogeneous. With regard to the retailers demands in every period, the supplier makes decisions about the weight and volume of the freight, the number and types of vehicles to be dispatched, and the amount of every product types to be delivered to each retailer. The carbon emission factor is defined as being dynamic in the sense that it changes based on the weight of the freight and the type of vehicle dispatched. The presented model is a mixed integer non-linear programming, which is first linearized through certain techniques, that allows us to obtain optimal solutions for small and medium sized instances. Moreover, different scenarios are provided in order to show the application of the model in practice, and certain managerial insights are given. Results show that with the increase of the number of periods, transportation costs and the total cost increase strictly. Moreover, there is a tendency to use vehicles with higher capacities whilst carbon emission costs never exceeds ten percent. Changes in the weight and volume of the products which are to be delivered affect the costs of the supply chain. Even when the total weight of the freight remains constant, these changes alter the percentage of the ratio of carbon emission costs to the total cost. Although increase in the weight and volume of products results in an increase of the total cost, this is not the case for carbon emission costs which are only affected by the weight and the type of vehicle dispatched. As tax rates increase, the total cost as well as carbon emission costs increases, whereas the amount of carbon emissions decreases. If tax rates increase, vehicles with higher pollution standards will be gradually used.