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Results 361-370 of 698 (Search time: 0.002 seconds).
  • Authors: Mai Quan Doan; Nguyen Ha Anh; Nguyen Xuan Quang; Ngo Xuan Dinh; Doan Quang Tri; Tran Quang Huy; Anh-Tuan Le;  Advisor: -;  Co-Author: - (2021)

    An electrochemical approach has been used for green synthesis of gold and silver nanoparticles (e-AuNPs and e-AgNPs) with high levels of purity and scalability. The electrochemically synthesized noble-metal nanoparticles were characterized by ultraviolet–visible (UV–Vis) spectroscopy and scanning electron microscopy (SEM), confirming the formation of spherical e-AuNPs and e-AgNPs with average size of 19 nm and 24 nm, respectively. These green nanoparticles were deposited on aluminum substrates using the drop-drying method for surface-enhanced Raman scattering (SERS)-based detection of Methylene Blue (MB) within the ranges from 10−5 M to 10−8 M and 10−7 M to 10−10 M, respectively. The SERS sensors also exhibited outstanding sensing performance for MB detection with limits of detectio...

  • Authors: Amélie Schultheiss; Abderrahime, Sekkat; Viet Huong, Nguyen;  Advisor: -;  Co-Author: - (2022)

    Poly(3,4-ethylenedioxythiophene) (PEDOT) is a transparent conductive polymer widely used in flexible photonic and optoelectronic devices because of its excellent electrical and optical properties. However, its current range of applications is limited by its poor stability under high humidity and solar radiations. Encapsulation is an attractive solution to this problem and the development of a low-temperature and scalable deposition method is highly desirable. In this study, we report the use of spatial atomic layer deposition (SALD) to deposit ultrathin layers of ZnO, TiO2, and Al2O3. These nanolayers maintain the electrical performance of the conductive polymer and its high optical transmittance. The use of SALD ensures low-cost and flexible processing with pinhole-free high-qualit...

  • 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: Duc, M. Tran; Duy, V. Nguyen; Bin, Ho Le; Hung, Q. Nguyen;  Advisor: -;  Co-Author: - (2022)

    We execute the quantum eraser, the Elitzur–Vaidman bomb, and the Hardy’s paradox experiment using high-level programming language on a generic, gate-based superconducting quantum processor made publicly available by IBM. The quantum circuits for these experiments use a mixture of one-qubit and multi-qubit gates and require high entanglement gate accuracy. The results aligned with theoretical predictions of quantum mechanics to high confidence on circuits using up to 3 qubits. The power of quantum computers and high-level language as a platform for experimenting and studying quantum phenomena is henceforth demonstrated

  • Authors: Tien Thinh, Le; Minh Vuong, Le;  Advisor: -;  Co-Author: - (2022)

    This work develops a Neural Network (NN) model for the prediction of the tensile modulus of carbon nanotube (CN)/polymer nanocomposites, based on experimental database. A data set composed of 282 configurations is collected from available resources. Considered input variables of the dataset are such as mechanical properties of separated phases, density of polymer matrix, processing method, geometry of CN, modification method at the CN surface, etc. while the problem output is the tensile modulus of nanocomposite. Parametric studies have been performed in finding optimum architecture of the proposed NN model.

  • Authors: Ho, Van Minh Hai; Nguyen, Duc Cuong; Mai, Duy Hien; Hoang, Thai Long; Tran, Quy Phuong; Tran, Khoa Dang; Le, Viet Thong; Nguyen, Ngoc Viet; Nguyen,Van Hieu;  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: Vidal, Thibaut;  Advisor: Martinelli, Rafael; Pham, Tuan Anh; Hà, Minh Hoàng;  Co-Author: - (2021)

    Vehicle routing algorithms usually reformulate the road network into a complete graph in which each arc represents the shortest path between two locations. Studies on time-dependent routing followed this model and therefore defined the speed functions on the complete graph. We argue that this model is often inadequate, in particular for arc routing problems involving services on edges of a road network. To fill this gap, we formally define the time-dependent capacitated arc routing problem (TDCARP), with travel and service speed functions given directly at the network level. Under these assumptions, the quickest path between locations can change over time, leading to a complex problem that challenges the capabilities of current solution methods. We introduce effective algorithms for...

  • Authors: Vu, Thi Lien; Vu, Ngoc Pi; Nguyen, Thi Quoc Dung;  Advisor: -;  Co-Author: - (2022)

    This study presents a comprehensive method for designing a multifocal contact lens (MCL) with Snell’s law and non-uniform rational B-spline (NURBS) curves. Instead of using thin lens approximation, general mathematical formulas have been developed to achieve the accurate coordinates of points on the anterior lens surface profile of the MCL to meet various given optical power distributions. Then the NURBS curve is adjusted to fit these data points to obtain the smooth front lens surface profile. This method not only improves the accuracy of the optical power profiles of MCLs but also reduces the spherical aberration in near/distance optical zones. The experimental results show that the power profiles of soft MCLs agree with those of the simulation results and original design requirem...

  • Authors: Van-The Than; Thi-Thao Ngo; Jin H. Huang; Chi-Chang Wang; Vinh Hung, Tran;  Advisor: -;  Co-Author: - (2022)

    In this paper, a method for optimizing a cross-section of hollow square steel used in manufacturing a chair is presented. The chair model is de-signed with dimension according to Vietnamese standards. A static analysis model of the chair is established and then solved to find the results such as factor of safety, mass and fatigue life. Response optimization module in Ansys software is applied to optimize the cross-section of chair frame including width and thickness. Different standardized dimension levels of the steel cross-sections are performed to carry out simulated results. Based on required safety factor, mass and fatigue life, some candidate points are given and further evaluated an optimal parameter.

  • Authors: Nguyen Le Nhat Trang; Van-Tuan Hoang; Ngo Xuan Dinh; Le Thi Tam; Van Phan Le; Dong Thi Linh; Doan Manh Cuong; Nguyen Tien Khi; Nguyen Ha Anh; Pham Tuyet Nhung; Anh-Tuan Le;  Advisor: -;  Co-Author: - (2021)

    In this work, an eco-friendly approach for the synthesis of biogenic silver nanoparticles (bio-AgNPs) using botanical extracts in combination with an electrochemical process was carried out. We employed three types of plant extracts, including green tea leaf (GTE), grapefruit peel (GP), and mangosteen peel (MP) extracts to successfully synthesize the bio-AgNPs and optimized the experimental conditions aiming to get the highest synthetic yield. The formation of bio-AgNPs was monitored by UV-Vis spectroscopy via a surface plasmon resonance (SPR) band at about 420–430 nm. Transmission electron microscope (TEM) showed their spherical shape with the size range within 23–55 nm. While X-ray diffraction (XRD) analysis described in detail the crystalline structure of the bio-AgNPs with a fac...