Abolfazl Mirzazadeh

This paper presents a Location-Allocation-Vehicle Routing Problem to design a humanitarian blood supply chain in response to earthquakes, incorporating quality concepts, reliability, and horizontal communication. The aim of the model is to minimize the total cost, minimize maximum shortage of demand points with high priority and low route value, and maximize the satisfaction of customers, including donors, hospitals, and blood transfusion centers. In order to deal with considerations of real world, the structure of the blood supply chain and all the intricacies incorporated in the model are defined based on the network and challenges of Blood Transfusion Center of Tehran. In addition, the blood demand and reliability of routes and facilities are considered uncertain, and the Interval Evidential Reasoning (IER) approach is used to handle the uncertainty. Since the problem is NP-hard, NSGAII and MOPSO algorithms have been applied to solve it. To demonstrate the efficiency of the model and compare the algorithms, several numerical examples in different sizes are designed. Finally, the most favorable algorithm is chosen for each size using the TOPSIS method.

In the classical inventory systems, the retailer had to settle the accounts of the purchased items at the time they were received. But in practice, the supplier applies some strategic tools, such as trade credit contract, to enhance his sales channel and offers delay period to his customers to settle the account. Any member of the supply chain may offer full or partial trade credit contract to his downstream level. Full trade credit is the case that the latter is allowed to defer the whole payment to the end of the credit period. In partial trade credit, however, the downstream supply chain member must pay for a proportion of the purchased goods at first and can delay paying for the rest until the end of the credit period. This paper considers a two-level trade credit, where the supplier offers order-quantity-dependent partial trade credit to a retailer, who suggests full trade credit to his customers. An economic order quantity (EOQ) inventory model of a deteriorating item is formulated here, and the Branch and Reduce Optimization Navigator is applied to find the optimal replenishment policy. The sensitivity of the variables on different parameters has been analyzed by applying some numerical examples. The data reveal that increasing the credit periods of the retailer and the customers can decrease and increase the retailer’s total cost, respectively.