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  • Authors: M. Elsisi; Minh-Quang Tran; Vu, Thi Lien; Nguyen, Thi Thanh Nga;  Advisor: -;  Co-Author: - (2022)

    Managing procedure for charging and discharging battery system plays an essential contributor in improving the performance of energy storage system for example increment of utilizing batteries. This paper aims to develop a new hybrid genetic algorithm-based proportional integral (GA-based PI) controller with an adaptive neuro-fuzzy inference system (ANFIS) for the charging balance of batteries. The dataset is generated by using the GA-based PI controller, then a training strategy is introduced for the ANFIS controller. The proposed approach is evaluated by the GA-based PI controller and the PI controller based on Ziegler Nichols method.

  • Authors: Ho, Van Minh Hai; Nguyen, Duc Cuong; Hien Duy, Mai;  Advisor: -;  Co-Author: - (2022)

    The assembly of primary nanoparticles to form hierarchical ultra-porous architectures is of great interest in various fields because of their extremely large surface area and porosity. In this work, the 3D ultra-porous γ-Fe2O3 nanocubes were synthesized by a simple method, which was derived from perfect Prussian Blue nanocubes by the oxidative decomposition process. The as-synthesized 3D γ-Fe2O3 nanocubes possess a large specific surface area and high porosity, which arise from the self-assembly of ultrafine nanoparticles. The 3D ultra-porous γ-Fe2O3 nanocubes-based sensors showed superior detection of acetone and ethanol with excellent sensitivity and rapid response time. The fantastic gas-sensing platform of 3D γ-Fe2O3 nanocubes could originate from their unique structures and int...

  • Authors: Ngo, Trong Hai; V. S. Luong; Ramesh, Chandra Bhatt; Lin-Xiu Ye; Te-ho Wu; Lance Horng; Jong-Ching Wu;  Advisor: -;  Co-Author: - (2022)

    It is commonly known that the coercivity (Hc) of the rare-earth/transition-metal (RE–TM) compound is tuned based on the varying RE content as compared to the TM component. The drawback of this approach is that the Hc changes are permanent. In this work, we investigate the coercivity behaviors of the GdFeCo/Hf/MgO heterostructure where the heavy metal Hf layer is inserted in the middle not only to convert charge current into spin current but also to prevent the oxygen diffusion effect. A strong geometry dependence of coercivity detected on Hall bar devices is attributed to the intrinsic properties of GdFeCo and elucidates that the oxidation issue from MgO on GdFeCo is prevented.

  • Authors: Dung, T. K. Ha; Canh, V. Pham; Huan, X. Hoang;  Advisor: -;  Co-Author: - (2022)

    The field of Submodular Maximization subject to a Knapsack constraint has recently expanded to a variety of application domains, which is facing some challenges such as data explosions or additional conditions. There exist plenty of objective functions that cannot be evaluated exactly in many real cases unless they are estimated with errors. It leads to solving the problem under noise models. Somewhat surprisingly, Submodular Maximization subject to a Knapsack constraint under Noise models (SMKN) has never been discussed a lot before. Hence, in this paper, we consider the problem with two kinds of noise models which are addition and multiplication. Inspired by the traditional Greedy algorithm, we first propose a Greedy algorithm under Noises with provable theoretical bounds. In orde...

  • Authors: Thi Thu Hoai, Bui; Thi Thu Huong, Tran; Dinh Kien, Nguyen;  Advisor: -;  Co-Author: - (2022)

    Geometrically nonlinear behavior of functionally graded (FG) beam and frame structures under mechanical loading is studied in this paper using the finite element method. The structures are made of a mixture of ceramic and metal with material properties varying in the thickness direction by a power distribution law. Based on the first-order shear deformation theory, a nonlinear beam element is derived and used in conjunction with Newton-Raphson method to compute deflected curves of the beams. Numerical investigations are carried out in detail to highlight the influence of the material distribution on the nonlinear behavior of the beams.

  • Authors: Chao, Xu; Thien, Van Luong; Luping, Xiang; Shinya, Sugiura; Robert, G. Maunder; Lie-Liang, Yang; Lajos, Hanzo;  Advisor: -;  Co-Author: - (2022)

    A variety of deep learning schemes have endeavoured to integrate deep neural networks (DNNs) into channel coded systems by jointly designing DNN and the channel coding scheme in specific channels. However, this leads to limitations concerning the choice of both the channel coding scheme and the channel paramters. We circumvent these impediments and conceive a turbo-style multi-carrier auto-encoder (MC-AE) for orthogonal frequency-division multiplexing (OFDM) systems, which is the first one that achieves the flexible integration of DNN into any given channel coded systems while achieving an iteration gain. More explicitly, first of all, we design the MC-AE independently of both the channel coding arrangement and of the channel model, where the output layer of the MC-AE decoder is des...

  • Authors: N.N.Hieu; P.N.Chung;  Advisor: -;  Co-Author: - (2021)

    In this paper, the authors investigate the stability and stick-slip motion of a friction-induced vibrating system placed on a belt moving at constant velocity using two-state model with consideration of dwell-time effect. The two-state model can be considered as an extension of the LuGre model because it can capture both Stribeck and dwell-time effects in the case of near-zero relative motion velocity between two surfaces. The previously known Stribeck effect is that the friction force decreases as the relative velocity increases in the near-zero range, while the dwell-time effect exhibits that the friction force increases as two surfaces are kept in contact for a certain time. With new effect of dwell-time, properties of stick-slip motion are explored in detail, including the equil...

  • Authors: Vinh Van, Le; Thi Hinh, Dinh; Thao T. Nguyen; Ha Thi Thanh, Nguyen;  Advisor: -;  Co-Author: - (2022)

    Multiphase Al2O3 samples are simulated using molecular dynamics method. These samples consist of γ-Al2O3 and α-Al2O3 crystals embedded in a disordered phase matrix. The stress–strain curves of these samples show elastic and plastic deformation. Structural analysis indicates that the AlO bond lengths are stretched and the geometries of the AlOx (x = 4, 5, and 6) units are distorted during tensile deformation. AlO bond breakage causes the transformation of AlOx units; AlO4 increases while AlO6 decreases with increasing strain. The γ-Al2O3 and α-Al2O3 crystals transfer into the disordered phase, while a small number of atoms recrystallize under tensile loads. In plastic deformation, large simplexes with radii above 1.958 Å increase rapidly with increasing strains above 0.116, with th...