Truong Giang - Academia.edu (original) (raw)

Papers by Truong Giang

─ This paper proposes an adaptive null-steering beamformer based on Bat Algorithm (BA) for Unifor... more ─ This paper proposes an adaptive null-steering beamformer based on Bat Algorithm (BA) for Uniform Linear Array (ULA) antennas to suppress the interference. The beamformer is targeted at steering nulls of ULA pattern in the directions of the interferences. The amplitude-only nulling method has been utilized for adjusting excitation weight of each array element. In order to validate the proposal, several scenarios of ULA array pattern imposed with the prescribed nulls have been investigated and compared with those of accelerated particle optimization (APSO) and genetic algorithm (GA). The proposed beamformer has shown the ability to suppress sidelobes and to place precisely single, multiple, and broad nulls at arbitrary interference directions. Furthermore, the beamformer is much faster and more effective than APSO and GA-based ones. Index Terms ─ Array pattern synthesis, bat algorithm, beamformer, beamforming, interference suppression, null-steering, ULA antennas.

Journal of Electromagnetic Waves and Applications, 2020

In this study, an adaptive pattern nulling approach of half-wave dipole uniform linear arrays (DU... more In this study, an adaptive pattern nulling approach of half-wave dipole uniform linear arrays (DULA), inspired by binary bat algorithm (BBA)-based beamformers and the phase-only control of array excitation weights, has been proposed. This helps suppress interference with unknown directions in the sidelobe region. Several scenarios have been conducted to investigate the performance of the proposal including operation speed and adaptive pattern nulling with or without the effect of mutual coupling. The simulation results show that the proposed approach is a potential solution to precisely place nulls at any direction of unknown interferences while maintaining the main lobe and suppressing the sidelobes. In addition, regarding the pattern nulling, the approach proposed in this study demonstrates greater efficiency and higher speed than those using binary particle swarm optimization (BPSO).

IEEE/ACES International Conference on Wireless Communications and Applied Computational Electromagnetics, 2005.

This paper presents a generalized approach to derive the dyadic Green's function of arbitrary mul... more This paper presents a generalized approach to derive the dyadic Green's function of arbitrary multilayer structures in planar, cylindrical and spherical coordinate systems. It is based on a full-wave equivalent-circuit representation that makes it possible to apply simple network analysis techniques. The planar stratified structures may be laterally bounded or open, the cylinders or spheres circumferentially closed or limited sectors. The procedure can be extended to other coordinate systems and anisotropic materials by means of a generalized transmission-line approach. For a demonstration of the applicability of this method, the derivation of the dyadic Green's functions in spectral domain of some commonly used cylindrical and spherical microstrip structures is presented.

2009 International Conference on Advanced Technologies for Communications, 2009

The recently developed method for the analysis of microstrip antennas on hemispherical structures... more The recently developed method for the analysis of microstrip antennas on hemispherical structures has been applied to derive the input impedance characteristics of quasi-rectangular microstrip antennas. By using corresponding full-wave equivalent circuits, the dyadic Green's functions of this structure and the system equation for the tangential field components at the interfaces can be analytically derived in a simple way. The Galerkin method-of-moments approach is used to solve the unknown current distribution on the patch, where the system equation involving the impedance matrix and the excitation vector can be set up and solved in the spectral domain. The computation data is verified with commercial software codes. Some advantages over commercial codes are also given. ©2009 IEEE.

Proceedings of the 5th International Confernece on Ubiquitous Information Management and Communication - ICUIMC '11, 2011

Claus Kuperschmidt Thomas Kaiser Institut for Communication Engineering Leibniz University of Han... more Claus Kuperschmidt Thomas Kaiser Institut for Communication Engineering Leibniz University of Hanover Appelstr. 9A 30167 Hanover, Germany kupfers@ikt.uni-hannover.de ... Truong Vu Bang Giang Tien Hoa Nguyen Faculty of Electronics and Telecommunications University ...

The 2011 International Conference on Advanced Technologies for Communications (ATC 2011), 2011

Abstract The basic structure of the Multi-Band Orthogonal Frequency Division Multiplexing (MB-OFD... more Abstract The basic structure of the Multi-Band Orthogonal Frequency Division Multiplexing (MB-OFDM) Ultra-Wide Band (UWB) System is discussed in this paper. The fixed-point simulation platform using the WiMedia Alliance proposed by ECMA 368 standards has ...

The Pediatric Infectious Disease Journal, 2009

Results presented as N (%) or median (interquartile range), unless otherwise noted. Abbreviations... more Results presented as N (%) or median (interquartile range), unless otherwise noted. Abbreviations: ARV=antiretroviral, EIA=HIV enzyme-linked immunoassay, SD=standard deviation. ** Univariate analyses conducted between EIA-negative vs. EIA-indeterminate and EIA-positive patients *** Percentages based on the denominator of mothers who received ARVs.

IEEE Transactions on Microwave Theory and Techniques, 2005

AbstractThis paper presents a uniform procedure to analyze radial waveguides, dielectric resonat... more AbstractThis paper presents a uniform procedure to analyze radial waveguides, dielectric resonators, dielectric resonator an-tennas, and microstrip antennas on spherical structures. It can be applied to any type of spherical multilayer closed and sector struc-tures, which ...

IEEE Transactions on Antennas and Propagation, 2008

AIDS and Behavior, 2000

The Ho Chi Minh City (HCMC) AIDS Committee is concerned about providing prevention and sexually t... more The Ho Chi Minh City (HCMC) AIDS Committee is concerned about providing prevention and sexually transmitted disease (STD) services to increasing numbers of female sex workers (FSWs). We interviewed 250 non-brothel-based FSWs in HCMC in 1997, ...

AIDS and Behavior, 2008

Pregnant and postpartum women with HIV often face stigma and discrimination at home and in the co... more Pregnant and postpartum women with HIV often face stigma and discrimination at home and in the community. In Vietnam, associations between HIV and the ''social evils'' of drug use and sex work contribute to stigmatization of people with HIV. We conducted a qualitative study to explore discrimination experienced by HIV-positive pregnant and postpartum women in Ho Chi Minh City at home and in the community. We conducted 20 in-depth interviews and two focus group discussions. Participants described managing disclosure of their HIV infection because of fear of stigma and discrimination, particularly to the wider community. In cases where their HIV status was disclosed, women experienced both discrimination and support. The findings highlight the need for targeted interventions to support pregnant and postpartum women with HIV, particularly during this period when they are connected to the healthcare system and more readily available for counseling.

AIDS and Behavior, 2006

Vietnam is in the midst of an expanding HIV epidemic, primarily driven by an increase in injectio... more Vietnam is in the midst of an expanding HIV epidemic, primarily driven by an increase in injection drug use in young people. This study was conducted to understand the patterns and initiation of drug use, and the sexual risk behavior among youth in three provinces in southern Vietnam. A cross-sectional survey was conducted among male and female drug users under age 25 recruited from drug treatment centers (N = 560) and the community (N = 240) in Ho Chi Minh City, Dong Nai and Ba Ria-Vung Tau. The majority of those surveyed (82%) began by smoking heroin; after a year, 57% were injecting heroin and/or opium. Initiation of drug use frequently occurred in entertainment venues. Among injectors, 23% shared needles; 71% of all users were sexually active of whom 77% had unprotected sex. More than half of those recruited from treatment centers had previously been in drug treatment. Public health programs to prevent and treat the dual epidemics of HIV and drug abuse must be able to access and respond to the needs of youth, many of whom are unemployed and exposed to drug traffic.