Proceedings of 7th Annual American Business Research Conference 23 - 24 July 2015, Sheraton LaGuardia East Hotel, New York, USA ISBN: 978-1-922069-79-5 A Model for Green Supply Chain Based on Reliability: Goal Programming Approach Seyed Sadegh Dajkhosh*, Ramin Sepehrirad**, Reza Dabestani*** and Haidar Almohri**** Closed-loop supply chain (Green CLSC) is defined as the supply chain activities to make use of products no longer required by the customer to usable products. This paper proposes a novel general multi-objective mixed- integer goal programming model for multi-product CLSC, where supply chain either can provide required parts from suppliers or cover the demand through reverse logistics loop. It is supposed that suppliers, refurbishing sites and remanufacturing subcontractor are multiple. We propose a multi objective mixed-integer linear programming model to determine which suppliers and refurbishing sites should be selected (strategic decisions), and find out the optimal number of parts and products in CLSC network (tactical decisions). The Goal programming model minimizes the cost, maximizes utilizing returned product and maximizes products reliability and the Green CLSC forces manufacturer to achieve required parts through closed-loop supply chain rather than buying new parts. A numerical example has been solved. JEL Codes: Closed-loop supply chain, Green CLSC, Goal programming, Reliability 1. Introduction High competitiveness and the emergence of new Information and Communication technologies in two early decades, has lead industrial enterprises to new activities such as procurement, distribution and logistics of supply chain management. As one of the key aspects of supply chain management, logistics try to improve the movement of products/parts between or within the facilities. In this field, closed-loop supply chain systems utilize used subsystems’ elements and components, together with new ones, which represents a special case of the management of closed loop supply chains, i.e. supply chains involving, among others, the reuse of products and materials, which are tackled in the recent literature with economic and environmental motivations (amin and ahang, 2012). In this paper we will introduce a new hard Multiobjective model for closed-loop supply chain using goal programming approach. _____________________ *Sadegh Dajkhosh, IE Department, Email: s.s.dajkhosh@gmail.com **Ramin Sepehrirad, IE Department, Email: r.seperirad$gmail.com ***Reza Dabestani, IE Department, Email: rdabest@yahoo.com ****Haidar Almohri, ISE Department, Email: almohri@wayne.edu Tarbiat Modares University, Tehran, Iran, Tarbiat Modares University, Tehran, Iran, Tarbiat Modares University, Tehran, Iran, Wayne 1 State University, Detroit MI, USA, Proceedings of 7th Annual American Business Research Conference 23 - 24 July 2015, Sheraton LaGuardia East Hotel, New York, USA ISBN: 978-1-922069-79-5 2. Literature Review Initially, the growing attention on Reverse Logistics (RL) and Closed-Loop Supply Chain (CLSC) issues originated with public awareness. Then governmental legislations forced producers to take care of their End of Life (EOL) products. For instance, the Waste Electrical and Electronic Equipment(WEEE) directive (directive 2002/96/EC) became European law in 2003, which contains mandatory requirements on collection, recycling, and recovery for all types of electrical goods, with a minimum rate of 4 kilograms per head of population per annum (Govindan, Soleimani & Kannan, 2015). Logistics can be divided into two categories of forward and backward. A backward movement can be described as a process that considers the return goods to suppliers called reverse logistics (Lu and Zhang, 2005). Reverse logistics or Closedloop supply chain is defined as the process of planning, implementing and controlling the inbound flow and storage of secondary goods and related information opposite to the traditional supply chain directions for the purpose of recovering value and proper disposal (Du and Evans, 2008). It encompasses all of the processes described in logistics, but in a reverse manner (Baenas et al. 2011). There are various motives for product remanufacturing e.g. increased profitability, ethical responsibility, legislation, secured spare part supply, increased market share and brand protection (Östlin, Sundin & Björkman, 2008). However, there are different types of reverse logistics models that can be considered according to the characteristics and requirements of the industry, but in general, the design of reverse logistics network is a difficult problem because of economic aspects and the effects on other aspects of human life, such as the environment and sustainability of natural resources (Francas & Minner, 2009). It has come to conclusion that this type of return is more predictable than others due to the additional information that is available to the remanufacturing company. In the automotive industry, there is widespread use of ‘‘exchange cycles’’ where products are only sold if a core is given back (Seitz and Peattie, 2004). Green logistics (CLSC) is receiving much attention recently due to growing environmental or legislative concerns and economic opportunities for cost savings or revenues from returned products (Roghanian & Pazhoheshfar, 2014). 3. Problem Definition We have proposed a general framework for the remanufacturing system in reverse logistics. In this study, a CLSC network that consists of disassembly, refurbishing and disposal sites is investigated. Figure.1 shows a general layout of a CLSC network. Remanufacturing process begins with the returned products from customers. First, these products are sent to the collection site. The used products are then moved to 2 Proceedings of 7th Annual American Business Research Conference 23 - 24 July 2015, Sheraton LaGuardia East Hotel, New York, USA ISBN: 978-1-922069-79-5 disassembly site. Therefore, the parts are divided into two categories of reusable and non-reusable products. Next, the useable parts are cleaned and repaired in the refurbishing site. Extra products beyond the disassembly and refurbishing capacity are transported to remanufacturing subcontractor. Finally, the outputs of remanufacturing subcontractor and refurbishing site are stocked in the part inventory in order to be used as a new part in the manufacturing process. Figure 1: A general green CLSC layout 4. Proposed model According to the proposed general green CLSC diagram, the goal programming model has been developed. The model and its indices is mentioned in the next part: π½ πΌ πππ π1 = ∑ ππππ π·πΌπππππ‘π + ∑(πππ + ππ‘ππ )π·ππ π + ππ ππ ππ·π + (πβπ + ππ‘ππ + ππ )ππ π π=1 π=1 πΌ π ′ + ∑ ∑ (ππππ + ππ‘ππππ + ππ‘ππππ )π πΉππππ‘ππ + ππ πππ ππ ππ π=1 π=1 πΌ πΏ πΌ πΎ + ∑ ∑ πππ πππππ‘ππ + ∑ ∑ ππ‘πππ π πππππ‘ππ (1 − π€ππππ ) π=1 π=1 π½ πΎ π=1 π=1 + ∑ ∑(ππππ + ππ‘πππ )π πππ ππ π=1 π=1 3 (1) Proceedings of 7th Annual American Business Research Conference 23 - 24 July 2015, Sheraton LaGuardia East Hotel, New York, USA ISBN: 978-1-922069-79-5 πΌ πΎ πΌ π πππ₯ π2 = ∑ ∑ π πππππ‘ππ (1 − π€ππππ ) + ∑ ∑ π πΉππππ‘ππ π=1 π=1 πΌ π=1 π=1 πΏ − ∑ ∑ πππππ‘ππ πΌ (2) π=1 π=1 π½ πΏ π½ πΌ π πππ₯ π3 = ∑ ∑ ∑ πΌππ πππ πππππ‘ππ + ∑ ∑ ∑ π½ππ πππ π πΉππππ‘ππ π=1 π=1 π=1 π½ πΌ π=1 π=1 π=1 πΎ + ∑ ∑ ∑ πΎππ πππ π πππππ‘ππ (−π€ππππ ) (3) π=1 π=1 π=1 π π’πππππ‘ π‘π π½ ∑ π£π ππ π ≤ πΆπππΆ (4) π=1 π½ ∑ π‘ππ π·ππ π ≤ πΆπππ· (5) π=1 πΌ ∑ π‘ππ π πΉππππ‘ππ ≤ πΆπππ πΉπ π = 1, 2, . . . . , π (6) π=1 π½ ∑ π πππ ππ ≤ πΆπππ ππ π = 1, 2, . . . , πΎ (7) π=1 πΌ ∑ πππππ‘ππ ≤ πΆππππ π=1 πΏ π = 1, 2, . . . , πΏ π (8) πΎ ∑ πΌππ πππππ‘ππ + ∑ π½ππ π πΉππππ‘ππ + ∑ πΎππ π πππππ‘ππ (1 − π€ππππ ) ≥ ππ ππππ‘π π π=1 π=1 = 1, 2, . . . , πΌ πΏ π=1 (9) π πΎ ∑ πππππ‘ππ + ∑ π πΉππππ‘ππ + ∑(1 − π€πππ )π πππππ‘ππ ≥ ππππ‘π π=1 π=1 π=1 = 1, 2, . . . , πΌ πΎ (10) πΎ π½ ∑ π πππππ‘ππ (1 − π€ππππ ) ≤ ∑ ∑ π πππ ππ π΅ππππ π=1 π π=1 π=1 = 1, 2, . . . , πΌ (11) 4 π Proceedings of 7th Annual American Business Research Conference 23 - 24 July 2015, Sheraton LaGuardia East Hotel, New York, USA ISBN: 978-1-922069-79-5 π π·πΌπππππ‘π + ∑ π πΉππππ‘ππ π=1 π½ = ∑ π·ππ π π΅ππππ π = 1, 2, . . . , πΌ (12) π=1 π½ π·πΌπππππ‘π ≥ ∑ π·ππ π π€πππ π΅ππππ π = 1, 2, . . . , πΌ (13) π=1 πΎ ππ π = π·ππ π + ∑ π πππ ππ ππ π ≤ ππ ππ’ π·ππ π ≤ π. ππ·π π = 1,2, … , π½ (14) π=1 π = 1,2, … π½ π = 1,2, … π½ π πΉππππ‘ππ ≤ π. ππ ππ (15) (16) π = 1,2, … , πΌ; π = 1,2, … , π (17) πππππ‘ππ , π πππ ππ , π πππππ‘ππ , π πΉππππ‘ππ , π·ππ π , ππ π , π·πΌπππππ‘π ≥ 0, πΌππ‘πππ ππ·π , ππ ππ = 0 ππ 1 Where indices include: π Set of parts π = {1,2, … , πΌ} π Set of products π = {1,2, … , π½} Variables and parameters Most of the variables and parameters are shown in figure 1 of the conceptual model, and the rest are described as follows: ππ·π , ππ ππ ππ πππ ππππ‘π Binary variable for set-up of disassembly product π & refurbishing part π at site π The unit price of purchasing Second-hand product π The unit purchasing cost of part π from supplier π The required 5 Proceedings of 7th Annual American Business Research Conference 23 - 24 July 2015, Sheraton LaGuardia East Hotel, New York, USA ISBN: 978-1-922069-79-5 ππππ ππππ πππ ππ ππ ππ πππ πβπ ππππ ππ‘ππ ππ‘πππ ππ‘πππ ππ‘ππ quantity of part π The remanufacturing cost for product π by subcontractor π The unit operation cost of refurbishing disassembled part π at of refurbishing site π The unit operation cost of disassembling product π The set-up cost for disassembling collected product π The set-up cost for refurbishing disassembled part π at site π The unit cost of holding product π The unit cost of disposing part π The unit cost of transporting product π to collection site The unit cost of transporting product π from collection site to subcontractor π The unit cost of transporting part π from subcontractor π to part inventory The unit cost of transporting product π from collection site to disassembly site 6 Proceedings of 7th Annual American Business Research Conference 23 - 24 July 2015, Sheraton LaGuardia East Hotel, New York, USA ISBN: 978-1-922069-79-5 ππ‘ππππ ′ ππ‘ππππ πΌππ , π½ππ , πΎππ π£π π‘ππ π‘ππ π΅ππππ ππ ππ’ The unit cost of transporting part π from disassembly site to refurbishing site π The unit cost of transporting part π from refurbishing site π to part inventory Reliability of part π produced by supplier π, refurbishing site π & subcontractor π The volume of the product π The required time for disassembling one unit of product π The unit required time for refurbishing one unit of part π The number of part π used in product j (Bill Of Material) The upper bound of returned product π 5. A Numerical Example Here, we have presented a numerical example to show the efficiency of the model. Researchers believe that the model can be solved optimally, rather than binary and integer variables. Consider a manufacturer that produces 3 types of products, each composed of 5 parts that can be achieved directly from one of five suppliers, three remanufacturer subcontractors, or five refurbishing sites. The needed amount of each part (ππππ‘π ) is 100, 500, 200, 700 and 50 respectively. Table .1 indicates the bill-of-material of each product (π΅ππππ ). The capacity of remanufacturing sites for each product or part type is set to be 800 m3 for collection site (assuming the volume of products are 12, 5 and 14 m3 respectively), 1000 minutes for disassembly site, 20 products for each remanufacturing subcontractors and 1200, 1500, 800, 7 Proceedings of 7th Annual American Business Research Conference 23 - 24 July 2015, Sheraton LaGuardia East Hotel, New York, USA ISBN: 978-1-922069-79-5 1000 parts for each refurbishing site. The upper bound of returned products is assumed 60 units for each type. Each supplier can deliver 80, 300, 250, 400, 150 parts of all types, respectively. Table 1: The BOM of products Product 1 Product 2 Product 3 Part 1 Part 2 Part 3 Part 4 Part 5 4 3 0 2 1 0 2 5 0 0 1 4 0 3 0 We have utilized goal programming method to solve the multi-objective model. Hence, we solve the single objective model for each objective function separately to achieve a goal for the linear goal programming. Table .2 indicates some information about the described models. The results are shown in Table .3; it indicates the number of purchased parts directly from the supplier. The remaining required parts must be covered from reverse logistic loop. Table .4 shows the number of returned and disassembled and outsourced products. Tables 5 and 6 illustrate the number of parts received from each subcontractor and refurbishing site respectively. Table 2: Solving time, memory used, number of iteration and objective function value πΉππ·πππππ πΉππ·πππππ πΉππ·πππππ πΉππ·πππππ Part 0 0 0 0 1 Part 35 0 0 0 2 Part 0 0 0 0 3 Part 0 0 23 0 4 Part 4 0 0 7 5 8 Proceedings of 7th Annual American Business Research Conference 23 - 24 July 2015, Sheraton LaGuardia East Hotel, New York, USA ISBN: 978-1-922069-79-5 Table 3: The number of purchased parts from suppliers Par t1 Par t2 Par t3 Par t4 Par t5 πΊπ·ππππππΊπ·πππππ πΊπ·ππππππΊπ·ππππππΊπ·πππππ 0 0 0 0 0 50 5 170 63 0 0 50 0 150 0 30 299 0 200 100 0 0 0 2 0 Table 4: The number of returned, disassembled, and out-sourced products to each subcontractor Produ ct 1 Produ ct 2 Produ ct 3 π·πΉπ π«π·πΉππΉπ΄π·πΉππ πΉπ΄π·πΉ ;π ;π ππ πΉπ΄π·πΉ ππ ; π =π =π =π 5 13 20 4 20 7 0 0 0 0 0 1 6 0 0 16 0 Table 5: The number of parts received from each subcontractor Par t1 Par t2 Par t3 Par t4 Par t5 πΉπ΄π·ππππΉπ΄π·πππ πΉπ΄π·πππ ππ ππ ππ 0 222 3 236 0 0 0 0 0 0 0 138 0 51 0 9 Proceedings of 7th Annual American Business Research Conference 23 - 24 July 2015, Sheraton LaGuardia East Hotel, New York, USA ISBN: 978-1-922069-79-5 Table 6: The number of parts received from each refurbishing site Objec tive functi on Cost Gree n Relia bility Multi Objec tive Iterati on 4302 42 2103 4773 1021 23 7104 76 Mem ory Use d (K) 62 75 55 71 OFV Optim al? 8365.7 20 326.48 42 2572.3 20 170.69 21 Yes Yes Yes Yes 6. Conclusion In This paper, we proposed a goal programming model for reverse logistics considering remanufacturing, repairing and recycling. Based on the framework of green CLSC in this study, a multi-objective integer programming model was proposed to optimize the performance of supply chain. First objective function (eq.1) minimizes total cost of covering required parts including the cost of purchasing parts from suppliers directly, the cost of buying, holding, disassembling, refurbishing, and remanufacturing used products, the cost of transportation over the network and the cost of disposing unusable parts. Second objective (eq.2) forces the manufacturer to cover its demands trough reverse logistics rather than purchasing new parts from suppliers. Since it tries to maximize the number of parts from reverse logistics, we called eq.2 as green objective. Third objective function (eq.3) maximizes the reliability of products whereπππ is proportion of part π on the reliability of productπ. The findings from the model solution indicate that there is an optimal solution for each facility. Therefore, the results may provide a guideline for companies which are interested to manage their products according to the reverse logistics system. 10 Proceedings of 7th Annual American Business Research Conference 23 - 24 July 2015, Sheraton LaGuardia East Hotel, New York, USA ISBN: 978-1-922069-79-5 References Amin, S. H., & Zhang, G. (2012). An integrated model for closed-loop supply chain configuration and supplier selection: Multi-objective approach. Expert Systems with Applications, 39(8), 6782-6791. Baenas, J. M. H., De Castro, R., Battistelle, R. A. G., & Junior, J. A. G. (2011). A study of reverse logistics flow management in vehicle battery industries in the midwest of the state of São Paulo (Brazil). Journal of Cleaner Production, 19(2), 168172. Du, F., & Evans, G. W. (2008). A bi-objective reverse logistics network analysis for post-sale service. Computers & Operations Research, 35(8), 2617-2634. Francas, D., & Minner, S. (2009). Manufacturing network configuration in supply chains with product recovery. Omega, 37(4), 757–769. Govindan, K., Soleimani, H., & Kannan, D. (2015). Reverse logistics and closed-loop supply chain: A comprehensive review to explore the future.European Journal of Operational Research, 240(3), 603-626. Lu, J., & Zhang, G. (2005). Personalized Multi-Stage Decision Support in Reverse Logistics Management. In Intelligent Data Mining (pp. 293-312). Springer Berlin Heidelberg. Östlin, J., Sundin, E., & Björkman, M. (2008). Importance of closed-loop supply chain relationships for product remanufacturing. International Journal of Production Economics, 115(2), 336-348. Roghanian, E., & Pazhoheshfar, P. (2014). An optimization model for reverse logistics network under stochastic environment by using genetic algorithm.Journal of Manufacturing Systems, 33(3), 348-356. Seitz, M., & Peattie, K. (2004). Meeting the closed-loop challenge. California management review, 46(2), 74-89. 11