javad jafarzadeh

Using a case study in scaffold production, this paper aimed to develop an integrated multi-objective mathematical model for a dynamic and sustainable cellular manufacturing system under fuzzy uncertainty. In this field, most studies have considered only the economic component or at most two components of sustainable production. Furthermore, with increasing concerns about global warming, environmental issues have become particularly important in manufacturing products and goods. On the other hand, customer satisfaction as one of the social responsibility cases is crucial because customer satisfaction is one of the factors of sustainability of organizations and companies in a competitive environment. Accordingly, sustainable production in this article consists of three components: economic, environmental, and social responsibility. We also subjected sustainable production in a dynamic cellular manufacturing system to fuzzy uncertainty. A sustainable multi-objective mathematical model with objective functions of minimizing costs, minimizing CO2 emissions, and minimizing product shortages (customer satisfaction) was proposed. A case study on scaffolding production was solved in GAMS software with CPLEX solver and augmented Epsilon-constraint method, and its basic variables were investigated to validate the proposed model. Then, due to the high complexity of the cellular manufacturing model, the NSGA-II and MOPSO meta-heuristic algorithms were applied to solve larger problems. As the results can be shown, the NSGA-II algorithm performed better than the MOPSO algorithm. Therefore, the results are then analyzed on the NSGA-II approach. The results indicate the proper performance of the proposed solution approach

In long-term gas contracts, there is usually a risk for the seller that the buyer will refuse to take delivery. For this reason, the condition of obligation to take or pay in such contracts has become common. Commitment condition is a condition that obliges the buyer in the gas sales contract to pay the seller a part of the contract price, which is determined as a percentage of the total amount, even if he does not receive the agreed gas volume. The research question is whether this condition has economic efficiency? Will a long-term balance between buyer and seller be an option for this condition in the contract or not? To answer these question, first, with the concept of evolutionary game theory, we have shown a picture of contracts before the existence of this condition and after its formation. Then, by setting the normal form of the game and using Python software, we have repeated this game thousand times, the results show that accepting the condition of commitment to take or pay will be stable evolutionary equilibrium. From this perspective, the inclusion of such a condition in the contract creates economic efficiency, and the policy recommendation in this regard would be for policy makers to prefer a lower definite income to a higher probable income by including such a condition.