Analysis Of Network Equilibrium And Robust H_∞Control Of Closed-loop Supply Chain Systems

Economic globalization, information and the requirements of human for the environment, especially in the structure of the domestic resource-conserving and environment-friendly society which make people pay much attention to closed-loop supply chain. As a system, the role of closed-loop supply chain is to coordinate the relationship among different members and in order to achieve the equilibrium state. The closed-loop supply chain network equilibrium model effectively achieves this goal. As the competition becomes increasingly fierce, enterprises must make quick response to the complication and changes of customer demands. Therefore, time is becoming a source of competitive advantage, which makes the study on dynamic characteristics of supply chain become a more important issue.With the consideration of multi-uncertainty, robust H∞control strategies are studied in order to achieve dynamic closed-loop supply chain system’s stability.Based on analyzing the existing study of the above topic, this thesis focuses on the coordination of closed-loop supply chain dynamic system’s network equilibrium problem and the robust H∞control strategies. The main contributions of this thesis include:First, we develop a closed-loop supply chain network equilibrium model, which consists of supplier, manufacturer, distributor, retailer, demand market and collector. On one hand, We develop a closed-loop supply chain network model in which both the demands associated with the retail outlets are random and the allowance policy to collectors by the government is consider in the formulation. We model the optimizing behavior of the various decision-makers, derive the equilibrium conditions, and establish the finite-dimensional variational inequality formulation. A modified projection method for variational inequality is used to solve numerical examples. It demonstrates the influence of the changing of parameters for the closed-loop supply chain equilibrium result; On the other hand, we develop a closed-loop supply chain network model in which both physical and electronic transactions are allowed and supply side risk as well as demand side risk and random demands are included in the formulation. We model the optimizing behavior of the various decision-makers, derive the equilibrium conditions, and establish the finite-dimensional variational inequality formulation. A closed-loop supply chain network equilibrium model with two-channel and multi-objective is obtained and a modified projection method for variational inequality is used to solve numerical example. The equilibrium prices and produce shipments will be helpful for enterprises.Second, the dynamic operation and control of closed-loop supply chain under multi-uncertainty are studied. On one hand, with the uncertain factors of remanufacturing rate parameter, remanufacturing time-delays and customer demand, the dynamic model of closed-loop supply chain based on electronic commerce is established. A robust H∞control is used to present optimal control strategy which guarantees the closed-loop supply chain dynamic system’s stability;On the other hand, the dynamic operation and control of closed-loop supply chain under multi-uncertainty are studied. Some uncertain factors such as remanufacturing time-delay, production time-delay, order time-delay, demand and recycling are considered. Operation robustness of closed-loop supply chain is analyzed, as well as the robust H∞control strategy of closed-loop supply chain and linear matrix inequality arithmetic is proposed. A robust H∞control is used to present optimal control strategy which guarantees the closed-loop supply chain dynamic system’s stability.