This paper focuses on rough approximation operators in group mapping. The relationships between rough set theory and group theory are considered from a novel perspective. The necessary and sufficient conditions for the upper approximation and lower approximation of a group to be groups are analyzed. In addition, the homomorphism and isomorphism between two groups which have related upper or lower approximations are investigated. Finally, the applications of rough approximation operators in group mapping to coding theory are developed.
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In recent years, closed-loop supply chain (CLSC) operation has been an important method to recover waste materials and products for resource conservation and environmental protection and paid more attention in industry and academia. We establish a dynamic model for closedloop supply chain with product recovering with the consideration of some uncertainties including remanufacturing rate, disposal rate, operation costs and customers’ demand in this paper. Furthermore, we provide some insights about robust operation of closed-loop supply chain and propose a robust H∞ control strategy based on linear matrix inequality (LMI) arithmetic. Some simulations are executed to validate the effectiveness of our control strategy, and the results show that through state feedback control of supply chain inventories, it can not only make the CLSC achieve the goal of restraining uncertainty disturbances, but also result in an ideal operation cost.
PL
Closed loop supply chain (CLCP – zamknięta pętla łańcucha zasobów) jest dziś ważną metodą odzyskiwania zmarnowanego materiału i produktu w celu ochrony środowiska i konserwacji zasobów. Zaproponowano model dynamiczny uwzględniający niepewności typu tempo produkcji, tempo usuwania, koszty operacyjne i żądania klienta.
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