Mohammad Ali najafi Nobar - Mster Graduate, Khaje Nasir Toosi University of technology, Department of Industrial Engineering, Tehran, Iran
Mostafa Setak - Assistant Professor Khaje Nasir Toosi University of technology, Department of Industrial Engineering, Tehran, Iran

In nowadays world competitive market , on account of the development of electronic media and its influence on shortening distances, companies require some core competitors in industry and sustain their situation in such a market . In addition companies achieve this target ree those which their processes perform great and exploit from competitive price, quality, tuarantee, etc. Since some parameters such as price and quality are so dependent on the performance of company supply chain management, so the results can highly impress the final price and quality of products. One of the main processes of supply chain management is supplier selection process which its accurate implementation can dramatically increase company competitiveness. In presented article two layers of suppliers have been considered as a chain of suppliers. First layer suppliers are evaluated by two groups of criterai which the first one encompasses criteria belongs to first layer suppliers features and the second group contais criteria belong to the characteristics of second layer suppliers. One of the criteria is the performance of second layer suppliers against environmental issues. Then the proposed approach is solved by a method combined of concepts of fuzzy set theory (FST) and linear programming (LP) which has been nourished by real data extracted from an engineering design and supplying parts company. At the end results reveal the high importance of considering second layer suppliers features as a criteria for selecting the best supplier.

Supply Chain Management (SCM) Supplier Selection, Second Layer Supplier, Green Factor, Linear Programming, Fuzzy Set Theory