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Second Order Suboptimal Power Allocation for MIMO-OFDM Based Cognitive Radio Systems
( Tien Hoa Nguyen ),( Thanh Hieu Nguyen ),( Van Duc Nguyen ),( Duyen Trung Ha ),( Guilllaume Gelle ),( Hyunseung Choo ) 한국인터넷정보학회 2014 KSII Transactions on Internet and Information Syst Vol.8 No.8
This paper proposes an efficient and low complexity power-loading algorithm for MIMO-OFDM downlink based cognitive radio system that maximizes the sum rate of single secondary user (SU) under constraints on the tolerable interference thresholds between secondary user and primary user`s frequency bands and the total transmission power. Our suboptimal algorithm is based on the 2<sup>nd</sup> order interference tracking and nulling mechanism to allocate transmission power of the subcarriers among SU`s scheme. The performance of our proposed suboptimal scheme is compared with the performance of the classical power loading algorithms, e.g., water filling, 1<sup>st</sup> order interference tracking, nulling, and other suboptimal schemes. Numerical results show that our algorithm has low complexity but obtains a higher channel capacity than that of some previous suboptimal algorithms in some scenarios. We dedicate also that for a given interference threshold, the 2<sup>nd</sup> order interference tracking mechanism has dynamic number of nulling position instead fixed number of nulling position.
Trung Tran,Loc Thi My Nguyen,Thanh Thi Nghiem,Hien Thi Thu Le,Cuong Huu Nguyen,Thuy Phuong La,Trung Tien Nguyen,Hang Thi-Thu Nguyen 한국과학학술지편집인협의회 2019 Science Editing Vol.6 No.2
This study aimed at elucidating the present situation of scholarly journals published in Vietnam according to the minimum criteria to be indexed in the ASEAN Citation Index (ACI) and Scopus, with the goal of suggesting development strategies for scholarly journals in Vietnam. From the 387 journals accredited by the Vietnamese State Council for Professorship, 13 education journals were arbitrarily selected, and their compliance with the five minimum criteria for the ACI (peer review, timeliness, abstracts in English, references in Roman script, and a website in English) and the six minimum criteria for Scopus (peer review, timeline, abstracts in English, references in Roman characters, Electronic International Standard Serial Number [ISSN], and publication ethics) were assessed. Two of the 13 journals were eligible to be indexed in the ACI, while none fulfilled the minimum criteria to be indexed in Scopus. An urgent task for the editors of those journals is to establish an informative journal homepage in English that provides basic information on the journal. Then, an Electronic ISSN can be obtained from the ISSN International Center. Furthermore, the following steps are suggested for journal promotion: establishment of appropriate editorial policies and publication ethics procedures, improvement of research integrity, enhancement of the journals’ reputation in the international scientific community, and improvement of the online publishing system by adopting a journal manuscript management system. To achieve those goals, financial support from the Vietnamese government will be invaluable.
Hien, Nguyen Khoa,Bao, Nguyen Chi,Ai Nhung, Nguyen Thi,Trung, Nguyen Tien,Nam, Pham Cam,Duong, Tran,Kim, Jong Seung,Quang, Duong Tuan Elsevier 2015 Dyes and pigments Vol.116 No.-
<P><B>Abstract</B></P> <P>A fluorescent chemosensor based on dimethylaminocinnamaldehyde-aminothiourea (DA) has been designed, synthesized, and applied with a combined theoretical and experimental study. The synthetic path, optimized molecular structure and characteristics of DA were carried out using the calculations at the B3LYP/LanL2DZ level of theory. The experimental investigations have a good agreement with the theoretical results. DA can be used as a chemosensor for simultaneous quantification of silver, copper, and mercury ions in aqueous solution at the ppb level. The stable geometric structures of the complexes between DA and Ag<SUP>+</SUP>, Hg<SUP>2+</SUP>, Cu<SUP>2+</SUP> with stoichiometry of 1:1, 2:1, and 2:1, have been found and investigated for electronic properties and fluorescence quenching phenomena by using Atoms in Molecules (AIM) and Natural Bond Orbitals (NBO) analyses.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A chemosensor has been studied with a combined theoretical and experimental study. </LI> <LI> Suitable for detecting trace amounts of Ag(I), Hg(II), Cu(II) ions at the ppb concentration level. </LI> <LI> High water solubility, simplicity, rapid analysis time, wide range of pH. </LI> <LI> The stable geometric structures of the complexes have been found and investigated. </LI> <LI> The fluorescence quenching of complexes is studied by using AIM and NBO analyses. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Cuong Huu Nguyen,Loc Thi My Nguyen,Trung Tran,Tien-Trung Nguyen 한국과학학술지편집인협의회 2020 Science Editing Vol.7 No.1
Purpose: This study aimed to analyze the bibliographic characteristics and content of articles on education published in Scopus-indexed journals by authors with Vietnamese affiliations from 2009 to 2018. Methods: Scopus was searched on July 6, 2019 using the search option “affiliation country,” with “Vietnam OR Viet Nam” as the country name, and “subject area” as “social sciences AND education.” Results: A total of 193 articles were identified. They were classified by publication year, co-authors’ country, affiliation, subarea, journal, and author. Content analysis of these articles demonstrated that the number of publications on education from Vietnam in Scopus increased rapidly during the last 10 years. The top five countries of co-authors were Australia, the USA, New Zealand, the UK, and the Netherlands. The main research subfields were English-language teaching, pedagogy, and educational management. Conclusion: Although Vietnamese education researchers collaborated with colleagues in developed countries to publish papers, there was still a lack of articles discussing global trends in education, such as cross-border education, equity in education, and international assessment programs.
Loc My Thi Nguyen,Tien-Trung Nguyen,Thanh Thi Nghiem,Hien Thu Thi Le,Thao Phuong Thi Trinh,Thuan Van Pham,Thanh Chi Nguyen,Linh Khanh Hoang,Trung Tran 한국과학학술지편집인협의회 2020 Science Editing Vol.7 No.1
In the context of the need to ensure appropriate signalling of the publication of high-quality, international-calibre publications in Vietnam, as well as new policies to improve the quality and effectiveness of scientific research in Vietnam, it is practical to investigate the possibility of developing a national open access database (NOAD). This study aims to answer the question of whether it is necessary to establish a NOAD in Vietnam. We used document analysis to evaluate issues related to NOADs. The results of this study show the complexity, lack of consistency, and difficulty in obtaining practical statistics and assessing research and scientific records in Vietnam today. Furthermore, the findings of this study imply that it is necessary to establish a NOAD of scientific research in Vietnam. The information in this report can be used to develop a NOAD for Vietnam in particular, and for any country that lacks one in general.
Vo, Vien,Nguyen Thi, Xuan Dieu,Jin, Ying-Shi,Ly Thi, Giang,Nguyen, Tien Trung,Duong, Tuan Quang,Kim, Sung-Jin Elsevier 2017 Chemical physics letters Vol.674 No.-
<P>Tin dioxide (SnO2) nanosheets/graphitic carbon nitride (g-C3N4) composite was prepared by a hydrothermal method using mercapto acetic acid as the morphology directing agent in an acidic medium. The as obtained composite was characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscope, and X-ray photoelectron spectroscopy; the results of this study show that in the composite, SnO2 nanosheets with a thickness in the range similar to 20-25 nm dispersed well on the g-C3N4. The lithium storage capability of the composite was investigated. The cycling performance of the composite was improved and is believed to be attributed by the presence of g-C3N4 support. (C) 2017 Elsevier B.V. All rights reserved.</P>