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Results 441-450 of 691 (Search time: 0.001 seconds).
  • Authors: Tran, Quang Huy; Khai Tuan, Nguyen; Phuc Thinh, Doan; Duc Tan, Tran;  Advisor: -;  Co-Author: - (2022)

    In ultrasound tomography (UT), Born iterative method (BIM) and distorted-Born iterative method (DBIM) based on Born approximation are considered efficacious. DBIM offers faster convergence compared to BIM; however, it is more susceptible to noise and vice versa. Combined or multi-model imaging is an indispensable trend of modern imaging to detect and accurately assess tissue states. The proposed method exploits the advantages, limiting the disadvantages and increasing the imaging speed of the merging of BIM and DBIM

  • Authors: Ta, Van Ranh; Le, Hong Ky; Tran, Vinh Hung;  Advisor: -;  Co-Author: - (2022)

    This paper presents research results on direct machining of Turbine blades in Turbocharger from point cloud data. In the study, the ATOS Core 80 scanner was used to create a point cloud file from the parts of the compression Turbine blades of the sample Turbocharger. From the point cloud data file, without any processing, the machining code is programmed using Inventor Professional software. The 5-axis HASS VF2 CNC milling machine is used to perform the machining steps. To evaluate the accuracy of machining parts compared with sample parts, the CMM coordinate measuring machine is used, and the original point cloud data file is compared with the detailed point cloud data file after processing by GOM Inspect software. The research results show that it is possible to directly machine T...

  • Authors: Nguyen, Le Nhat Trang; Dao, Thi Nguyet Nga; Van, Tuan Hoang; Xuan, Dinh Ngo; Pham, Tuyet Nhung; Anh,Tuan Le;  Advisor: -;  Co-Author: - (2022)

    The present work reports efficient electrochemical nanosensors for the sensitive monitoring of 4-nitrophenol (4-NP) in tomato samples using various biosynthesized silver nanoparticles (bio-AgNPs). Three different bio-AgNP types were synthesized using natural plant extracts, including green tea (GT) leaf, grapefruit peel (GP), and mangosteen peel (MP), aiming to investigate their effects on the formation of bio-AgNPs, as well as the analytical performance of 4-NP. Based on the obtained results, it was found that the phytochemical content in various plant extracts directly influenced the physicochemical parameters of the created bio-AgNPs, such as particle size, crystallinity, and distribution. More importantly, these parameters have decisive effects on the electrocatalytic activity, ...

  • Authors: Amit, Chanda; Derick, DeTellem; Yen, Thi Hai Pham;  Advisor: -;  Co-Author: - (2022)

    Understanding the effects of phase transition, phase coexistence, and surface magnetism on the longitudinal spin Seebeck effect (LSSE) in a magnetic system is essential to manipulate the spin to charge current conversion efficiency for spincaloritronic applications. We aim to elucidate these effects by performing a comprehensive study of the temperature dependence of the LSSE in biphase iron oxide (BPIO = α-Fe2O3 + Fe3O4) thin films grown on Si (100) and Al2O3 (111) substrates. A combination of a temperature-dependent anomalous Nernst effect (ANE) and electrical resistivity measurements show that the contribution of the ANE from the BPIO layer is negligible in comparison to the intrinsic LSSE in the Si/BPIO/Pt heterostructure, even at room temperature. Below the Verwey transition of...

  • Authors: Truong V. Vu; Binh D. Pham; Phuc H. Pham; Hung V. Vu; Bo X. Tran;  Advisor: -;  Co-Author: - (2021)

    We present a numerical investigation of the breakup and freezing of a pendant hollow water drop beneath a cold curved surface. The drop contains a bubble surrounded by a shell of water that forms at an outer wetting angle of θo with the surface. The freezing begins on the cold curved surface and evolves in the direction of gravity. As it freezes, the water accumulates and forms a bulbous end at the bottom of the drop. Breakup can occur, inducing a daughter water drop. As a result, the freezing process of the remaining hollow drop attached to the surface takes less time, and the frozen drop shrinks. However, this breakup has no effect on the bubble. The various parameters under consideration include the Bond number Bo, the Stefan number St, the size of the bubble, and the angle θo. I...

  • Authors: Duc Minh, Vu; Mike, Hewitt; Duc D.Vuc;  Advisor: -;  Co-Author: - (2022)

    In this paper, we present exact methods for solving the Time Dependent Minimum Tour Duration Problem (TD-MTDP) and the Time Dependent Delivery Man Problem (TD-DMP). Both methods are based on a Dynamic Discretization Discovery (DDD) approach for solving the Time Dependent Traveling Salesman Problem with Time Windows (TD-TSPTW). Unlike the TD-TSPTW, these problems involve objective functions that depend in part on the time at which the vehicle departs the depot. As such, optimizing these problems adds a scheduling dimension to the problem. We present multiple enhancements to the DDD method, including enabling it to dynamically determine which waiting opportunities at the depot to model. With an extensive computational study we demonstrate that the resulting methods outperform all know...

  • Authors: Quan Hoang, Vuong; Minh Hoang, Nguyen; Tam Tri, Le;  Advisor: -;  Co-Author: - (2021)

    The book examines the psycho-religious mechanism behind the violent extremism of suicide attacks in the post-9/11 world. It employs the mindsponge concept, an original dataset, and original research results obtained from the authors' statistical investigations using the Hamiltonian Markov chain Monte Carlo technique. It provides insights and implications for policymakers and strategists in their efforts to engage in peace talks and reduce violent conflicts worldwide.

  • Authors: Vu, Le Huy; Nguyen, Dinh Dung;  Advisor: -;  Co-Author: - (2022)

    This study aims at improving the control quality of parallel robot, where Rostock Delta robot is the main object. This study proves stability of the sliding mode control method when the dynamic parameters of Rostock Delta robot are uncertain. Numerical simulation is then performed for trajectory tracking problem of Rostock Delta robot using sliding mode control method, where the dynamic parameters are assumed in case to be precise and in case to be uncertain. The obtained results show agreement with the established theory.

  • Authors: Nguyen, Cuong T.;  Advisor: Vu, Hung V.; Vu, Truong V.; Truong, Thuan V.; Ho, Nang X.; Pham, Binh D.; Nguyen, Vinh T.; Nguyen, Hoe D.;  Co-Author: - (2021)

    Compound droplets with different sizes are increasingly used in industrial production and academic research. This study aims to improve understanding of the dynamical behaviors of the compound droplet moving in microchannels. The compound droplet consisting of one inner core is initially concentric and placed at the entrance of a circular channel with a cone at the downstream region. Following this primary channel is a secondary channel that is circular and straight. Manipulation of the droplet is assisted by a flow introduced via the gap between two channels. The numerical results show that when passing through these confined channels, the droplet experiences a finite deformation or breakup mode. In each mode, the deformation or breakup of the compound droplet is also different whe...

  • Authors: Thomas E. Jones; Minh, Hoang Nguyen;  Advisor: -;  Co-Author: - (2021)

    The rapid post-millennial internationalisation of Japan’s tourism sector and the influx of international visi-tors have quickly increased visitor motivations’ heterogeneity, thereby posing challenges for management. Given the lack of prior research, we aimed to identify nature-based tourism (NBT) push-factor motivation domains of visitors in a Japanese national park and segment domestic and international visitors based on their motivations, demographics and trip profiles. Primary data collection of 137 responses took place in November 2019 through an on-site self-admin-istered questionnaire. From 11 push-factor statements, the principal component analysis yielded a four-factor solution: ‘enjoying nature with family or friends’, ‘improving physical health’, ‘discovering and learning’...