امير حسنا

Abstract: In this study, a bi-level model for a sustainable inventory system has been developed to address environmental and social aspects of sustainability together for two issues of the deterioration and full backlogging. In this thesis, first, the Economic Order Quantity model (EOQ) was revised by adding the cost of sustainability to the cost function of the inventory system. Then, considering the amount of dust released from the cement production process, the optimization problem was formed at the follower level of a bi-level model. In order to evaluate the interdependence between the social and environmental indices in the model, the issue of optimizing the leader level was considered in terms of human factors in the two areas of auditory health and respiratory health. Since the general structure of the proposed bi-level programming includes nonlinear objective functions and constraints at first, using Karush -Kuhn-Tucker (KKT) optimization conditions, the bi-level model has been transformed into a single level problem. an‎d then was solved with nonlinear solver in GAMS optimization software. Finally, the efficiency of the model was evaluated in a real case study for the cement industry and led to significant results in three aspects (i.e. economic, environmental and social) sustainability. Among them, it can be mentioned into increasing the amount of profit obtained from the model of this study compared to the current situation of the studied industrial unit, the reduction of the mass of cement deposited in vegetation body in the study area compared to its current state and to compensating a large part of the auditory and respiratory pollutants according to the model obtained from this study compared to their current values within the industrial unit. Validation of the model was also carried out of the current situation of industrial unit as well as the models developed in this thesis. Keywords: Inventory Model, Sustainability, Cement Production Industry, Bi-level Optimization,