عنوان مقاله [English]
By increasing the environmental consciousness, reverse supply chain is getting known in business theory and application. However, the high costs of implementing them is one of the important impediments for managers. In the current paper, a variant of vendor managed inventory is proposed for parallel reverse supply chains and the cost functions are compared with the non-collaborative and simple collaborative cases. In the non-collaborative case, different reverse supply chains are working in isolation and there is no sharing between them. The simple collaboration is possible when the members just share a collection center as a warehouse. The proposed collaboration is designed such that these members share their information with collection center and this center plans for collecting and transferring returns to the recovery centers in a way that less inventory is hold at that center. To compare our model with the traditional and simple collaboration, the cost functions are defined for two parallel simple three tier reverse supply chains. In order to reflect the reverse supply chain uncertainties, probability distribution of the amount of returned products is considered at the cost functions. Then, the mathematical situation for superiority of the proposed model to non-collaborative and simple collaborative case is studied using these cost functions. Two mathematical non-equalities show these situations as the result of this part. As this collaboration is not used in the reality, to compare the results in actual case, some illustrative examples are created by two different probability distributions for return generation. Finally, a Monte Carlo simulation technique is used for about 100 samples in1000 periods. The average costs for different components of cost function are calculated. Comparing the costs shows 48% decrease in shifting from non-collaborative to simple collaborative, 54% decrease in changing the non-collaborative case to the proposed model, and 11% decrease in changing the simple collaboration to proposed one. However, the results show a high decrease in costs of the model and its superiority to other two cases. The model can be expanded to broader and longer reverse supply chains by future researchers. Some other opportunities for study subjects are also introduced in the last section.