Multipurpose optimization of facility location and open routing problem in building material supply chain design: mathematical models and trans-innovative algorithms

In this research, the issue of open location and routing in the four-tier supply chain, including suppliers, manufacturers, distribution centers and retailers, is addressed using a multi-objective mathematical model and taking into account the factors of sustainable development. Material transportation between all levels is direct and is routed between distribution centers and customers as well as manufacturers with customers. The flow of raw materials between suppliers and producers will be based on the technical specifications of the final products. In other words, for each final product, the required composition of raw materials is determined as the input parameter and based on that, the required amount of raw materials for the production of each product is estimated. In many studies, it is assumed that the vehicles are assets to the organization and must return to the distribution center after providing the service. In distribution centers, in order to create flexibility in meeting customer demand, different capacity levels are considered, with the employment of each capacity level having different environmental and social effects and are solved using the mathematical model of the Epsilon constraint method in small dimensions. NSGAII, PESAII and MOGWO meta-heuristic algorithms have been used to solve large-scale problems.