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Video viewing is currently the primary form of entertainment for modern people due to the rapid development of mobile devices and 5G networks. The combination of pervasive edge devices and adaptive bitrate streaming technologies can lessen the effects of network changes, boosting user quality of experience (QoE). Even while edge servers can offer near-end services to local users, it is challenging to accommodate a high number of mobile users in a dynamic environment due to their restricted capacity to maximize user long-term QoE. We are motivated to integrate user allocation and bitrate adaptation into one optimization objective and propose a multiagent reinforcement learning method combined with an attention mechanism to solve the problem of multiedge servers cooperatively serving users. Through comparative experiments, we demonstrate the superiority of our proposed solution in various network configurations. To tackle the edge user allocation problem, we proposed a method called attention-based multiagent reinforcement learning (AMARL), which optimized the problem in two directions, i.e., maximizing the QoE of users and minimizing the number of leased edge servers. The performance of AMARL is proved by experiments.

学位の種別: 課程博士, 審査委員会委員 : （主査）東京大学教授 髙橋 淳, 東京大学教授 岡部 洋二, 東京大学准教授 沖田 泰良, 東京大学准教授 ドドビバ ジョルジュ, 東京大学准教授 横関 智弘

Dry eye formation often originates from oxidative damage to the ocular surface, which can be caused by external environment or internal pathologic factors. Esculetin (6, 7-dihydroxycoumarin) is a natural product found in many plants, and has been reported to have multiple pharmacological activities. The objective of our present study is to investigate if esculetin could protect the corneal epithelial cells from oxidative damages and its underlying antioxidant molecular mechanisms. Our experimental results demonstrated that pretreatment with esculetin markedly increased the cell viability while decreased the apoptosis in H2O2-treated human corneal epithelial (HCE) cells, by regulating Bcl-2, Bax and caspase-3 protein expressions and by altering the imbalance of activities of intracellular reactive oxygen species (ROS) and superoxide dismutase (SOD). Our data revealed that esculetin played an antioxidant role not only through its antioxidant activity, but also by highly inducing Nrf-2 translocation to the nucleus, which in turn, enhanced Nrf2 signaling regulated antioxidant genes (HO-1, NQO1, GCLM, SOD1 and SOD2) mRNA expression levels in H2O2-treated HCE cells. In the present study, the protective effects of esculetin on the corneal epithelium were also confirmed by a murine desiccating stress induced dry eye model in vivo. These data illustrated, for the first time, that esculetin may have the ability to protect human corneal epithelial cells from oxidative damages through its scavenging of free radical properties and through the activation of Nrf2 signaling.

At present, China is in the stage of transition from the monopoly and unified management mode of the traditional power system to an open power market. The formation of a good market model and rules can meet the needs of fair competition, improve the production efficiency and service level of power enterprises, and reduce production costs. This article mainly introduces three methods of stability analysis, and expounds the potential risks and solutions facing China's power market from the perspective of risk management.

This paper presents the application of data processing technique to the spray analysis of a diesel nozzle. Faced with a large number of oil droplets, we have used several techniques to improve the image quality and to make the processing more rapid and reliable.