چكيده به لاتين
Abstract:
Improving the efficiency of logistics operations and costs is a issue that has been emphasized both in the business world and in the research world. Companies have always been looking for solutions to create competitive advantage to reduce their logistics costs, thereby reducing the cost of their products. The transportation system is one of the industry sectors that has a major role in greenhouse gas emissions and dangerous environmental effects in the form of energy use and acidification. Locating distribution and routing centers is one of the most challenging issues in supply chain management. Separate examination of these two issues results in increased costs and scheduling time. Therefore, a location-routing problem is proposed to simultaneously determine location and routing decisions in the design of supply chain networks. Therefore, in this research, the supply chain under study consists of three parts: warehouses, customers and collection centers. In order to model this problem, two integer linear mathematical models are presented based on stochastic programming and robust programming. In this research, the aim is to find optimal warehouses and collection centers and to find optimal service routes for customers. Optimal locations for storage facilities should be considered and simultaneously optimal routes should be found for customer service. The two previous decisions will be taken in such a way that the total routing costs (distance, fuel, ....) and location of the facility (start up costs, property costs or rentals, etc.), and greenhouse gas costs Minimize. For numerical analysis of the models, numerical analysis has been investigated. GAMS software and CPLEX solver have been used to solve the model. For model data, a numerical example is generated with hypothetical data. Then, stochastic and Robust models are solved using this data and the results of the models are presented and for the stochastic model, EVPI and VSS indices are calculated. Finally, sensitivity and validation analysis is presented on the model. Also, to solve in higher dimensions, a new metaheuristic algorithm based on the genetic algorithm has been developed.
Keywords: Location-Routing Problem, Green Routing, Simultaneous Pick-Up and Delivery, Stochastic Programming, Robust Programming.
