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Results 191-200 of 698 (Search time: 0.001 seconds).
  • Authors: Tianxu, Li; Kun, Zhu; Nguyen, Cong Luong; Dusit, Niyato; Qihui, Wu; Yang, Zhang; Bing, Chen;  Advisor: -;  Co-Author: - (2022)

    Future Internet involves several emerging technologies such as 5G and beyond 5G networks, vehicular networks, unmanned aerial vehicle (UAV) networks, and Internet of Things (IoTs). Moreover, the future Internet becomes heterogeneous and decentralized with a large number of involved network entities. Each entity may need to make its local decision to improve the network performance under dynamic and uncertain network environments. Standard learning algorithms such as single-agent Reinforcement Learning (RL) or Deep Reinforcement Learning (DRL) have been recently used to enable each network entity as an agent to learn an optimal decision-making policy adaptively through interacting with the unknown environments. However, such an algorithm fails to model the cooperations or competition...

  • Authors: Truong V. Vu;  Advisor: -;  Co-Author: - (2021)

    A compound droplet solidifying on a cold curved surface in a gaseous environment is numerically studied by an axisymmetric three-phase front tracking method. The compound droplet containing an inner core of gas is initially assumed to be part of a sphere, and the curved surface is maintained at temperature below the solidification point of the shell liquid. The effects of the radius of the cold surface, volume change (in terms of the solid-to-liquid density ratio ρsl), supercooling degree (in terms of the Stefan number St), growth angle ϕgr and shell liquid thickness on the solidified droplet shape, the solidification rate and the solidification times are under consideration. Volume expansion (ρsl < 1.0) induces an apex, and volume shrinkage (ρsl > 1.0) results in a cavity on top of...

  • Authors: Tran Khoa Dang; Nguyen Tang Son; Nguyen Thi Lanh; Phan Hong Phuoc; Nguyen Ngoc Viet; Le Viet Thong; Chu Manh Hung; Nguyen Van Duy; Nguyen Duc Hoa; Nguyen Van Hieu;  Advisor: -;  Co-Author: - (2021)

    External and internal heterojunctions of reduced graphene oxide (rGO) and ZnO nanofibers (NFs) are developed for ultrasensitive H2S sensing. The gas response of both heterojunctions is significantly higher than that of bare ZnO NFs. The internal heterojun

  • Authors: Dung Do Thi Thuy;  Advisor: Vu, Thi Ngoc Minh; Nguyen, Xuan Truong; Pham, Van Huan; Vuong-Pham Hung; Nguyen, Duy-Hung; Bui, Thi Hoan; Tu Le Manh; Hoang, Nhu Van;  Co-Author: - (2021)

    This work presents a novel multifunctional material synthesized by hydroxyapatite/ β-tricalcium phosphate (HA/β-TCP) doped with Er-Yb-Mo ions (using hydrothermal method) and its characterization, showing a peculiar property of green dual-mode emissions (up and down-conversions). It was found that the obtained material exhibits an intense green emission (510–560 nm) both via up-conversion (excited by 975 nm) and down-conversion (excited by 379 nm), which depend on the Mo6+ contents. Particularly, compared with the free-Mo6+ sample, the green emission intensities of the samples doped with 5% Mo6+ mol are 50 and 35 times higher for UC and DC emissions, respectively. Furthermore, the temperature sensing property of the HA/β-TCP: Er-Yb-Mo composite is investigated by fluorescence intensi...

  • Authors: Quang-Cherng Hsu; Vinh -Hung Tran; Anh-Tuan Do; Tat-Tai Truong;  Advisor: -;  Co-Author: - (2022)

    Design of extrusion dies for complex solid profiles with varying wall thickness to ensure the flow balance in the extrudate is difficult. The type of dies and their structure, which directly affect the quality of the extruded product, are significantly influenced by experience of the designer. In this study, two types of dies, including feeder die and porthole die, were designed for extruding a complex heatsink profile. The basic dimensions of the feeder die were similar to the porthole die except for the bridge structure. Steady-state extrusion simulations of these two dies using HyperXtrude software were carried out. The numerical analysis results revealed that the porthole die with a unique bridge design offered a better distribution of velocity and residual stress in the extruda...

  • Authors: Anh D. Phan; Nguyen K. Ngan; Nam B. Le; Le T. M. Thanh;  Advisor: -;  Co-Author: - (2021)

    Physical properties of the pressure-induced activation volume and dynamic decoupling of ternidazole, glycerol, and probucol by the elastically collective nonlinear Langevin equation theory is theoretically investigated. Based on the predicted temperature dependence of activated relaxation under various compressions, the activation volume is determined to characterize effects of pressure on molecular dynamics of materials. It is found that the decoupling of the structural relaxation time of compressed systems from their bulk uncompressed value is governed by the power-law rule. The decoupling exponent exponentially grows with pressure below 2 GPa. The decoupling exponent and activation volume are intercorrelated and have a connection with the differential activation free energy. Rela...

  • Authors: Govindaraj Ramya; Govindaraj Priya; Chowdhury Subrata; Dohyeun Kim; Duc Tan Tran; Anh Ngoc Le;  Advisor: -;  Co-Author: - (2021)

    The extremely vibrant, scattered, and non–transparent nature of cloud computing formulate trust management a significant challenge. According to scholars the trust and security are the two issues that are in the topmost obstacles for adopting cloud comput