چكيده به لاتين
Nowadays, supply chains Compete with each other in the world of commerce. In addition to the economic aspect, in the context of sustainable development, attention to environmental and social issues has also been the focus of the researchers and activists of this field. One of the most important functions along the chain that is economically significant and also is important in terms of sustainability considerations is the vehice routing. Two-echelon vehicle routing problem is related to distributing goods from central warehouses to final costumer through intermadite facilities or warehouses calles satelites. The nature of this problem is consistent with the today’s life becauses distribution is done through appropriate vehicles (urban and suburban) in each level. The aim of this problem is to provide optimal routes for suburban vehicles (first level) and urban vehicles (second level) integrately by minimizing the total cost of the chain. In this study, a multi-period two-echelon vehicle routing problem in a multi-product supply chain is formulated which considers environmental as social objectives besides of economical objective. The proposed model is robust against travel time uncertainty in the second level.Decision variables are inventory levels in final demand nodes and intermediate warehouses, routing of the vehicles in the both levels, scheduling of the vehicles travel and also the amount of answered demands in warehouses and final nodes in each period by each vehicle. the model has NPhard complexity and it is necessary to develop a meta-heuristic algorithm to solve it in the size of real life problems. A simulated annealing based algorithm is introduced in this study which can produce optimum soloutions in small and medium problem sizes and used for solving the real life problem of the case study. The real datas are extracted from an Iraninan food-distribution supply chain case and the model is solved and the results are reported. Results and discussion show the validity of the model.
Keywords: Supply Chain, Sustainability Indexes, Two echelon vehicle routing problem, Inventory- Routing, Simulated annealing.
