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High-Resolution Simulations for Vietnam - Methodology and Evaluation of Current Climate
Jack Katzfey,Kim Nguyen,John McGregor,Peter Hoffmann,Suppiah Ramasamy,Hiep Van Nguyen,Mai Van Khiem,Thang Van Nguyen,Kien Ba Truong,Thang Van Vu,Hien Thuan Nguyen,Tran Thuc,Doan Ha Phong,Bang Thanh Ng 한국기상학회 2016 Asia-Pacific Journal of Atmospheric Sciences Vol.52 No.2
To assist the government of Vietnam in its efforts to better understand the impacts of climate change and prioritise its adaptation measures, dynamically downscaled climate change projections were produced across Vietnam. Two Regional Climate Models (RCMs) were used: CSIRO’s variable-resolution Conformal-Cubic Atmospheric Model (CCAM) and the limited-area model Regional Climate Model system version 4.2 (RegCM4.2). First, global CCAM simulations were completed using bias- and variance-corrected sea surface temperatures as well as sea ice concentrations from six Coupled Model Intercomparison Project Phase 5 (CMIP5) global climate models. This approach is different from other downscaling approaches as it does not use any atmospheric fields from the GCMs. The global CCAM simulations were then further downscaled to 10 km using CCAM and to 20 km using RegCM4.2. Evaluations of temperature and precipitation for the current climate (1980-2000) were completed using station data as well as various gridded observational datasets. The RCMs were able to reproduce reasonably well most of the important characteristics of observed spatial patterns and annual cycles of temperature. Average and minimum temperatures were well simulated (biases generally less than 1oC), while maximum temperatures had biases of around 1oC. For precipitation, although the RCMs captured the annual cycle, RegCM4.2 was too dry in Oct.-Nov. (−60% bias), while CCAM was too wet in Dec.- Mar. (130% bias). Both models were too dry in summer and too wet in winter (especially in northern Vietnam). The ability of the ensemble simulations to capture current climate increases confidence in the simulations of future climate.
Improving Deep CNN-Based Radar Target Classification Performance by Applying a Denoise Filter
Nguyen Van-Tra,Vu Chi-Thanh,Doan Van Sang 한국전자파학회 2024 Journal of Electromagnetic Engineering and Science Vol.24 No.2
This paper presents a novel method for removing noise from range-Doppler images by using a filter prior to conducting target classification using a deep neural network. Specifically, Kuan, Frost, and Lee filters are employed to eliminate speckle noise components from radar data images. Furthermore, a neural network that combines residual and inception blocks (RINet) is proposed. The RINet model is trained and tested on the RAD-DAR dataset—a collection of range-Doppler feature maps. The analysis results show that the application of a Lee filter with a window size of 7 in the RAD-DAR dataset demonstrates the most improvement in the model’s classification performance. On applying this noise filter to the dataset, the RINet model successfully classified radar targets, exhibiting a 4.51% increase in accuracy and a 14.07% decrease in loss compared to the classification results achieved for the original data. Furthermore, a comparison of the RINet model with the noise filtering solution with five other networks was conducted, the results of which show that the proposed model significantly outperforms the others.
Content-Aware Proactive Caching for Backhaul Offloading in Cellular Network
Doan, Khai Nguyen,Van Nguyen, Thang,Quek, Tony Q. S.,Shin, Hyundong IEEE 2018 IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS Vol.17 No.5
<P>Proactive caching is considered a cost-effective method to address the backhaul bottleneck problem in cellular network. In this paper, we propose a novel popularity predicting–caching procedure that takes raw video data as an input to determine an optimal cache placement policy, which deals with both published and unpublished videos. To anticipate the popularity of unpublished videos of which the statistical information is not available, we apply the content-based approach by extracting and condensing video features into a high-dimensional vector. Subsequently, we form <TEX>$G$</TEX> clusters of features representing the potential video categories (VCs) and map the feature vector into a <TEX>$G$</TEX>-dimensional space, where each element indicates the percentage to which the video contains the features of the corresponding VC. Finally, we train a prediction model to foresee the popularity, where the set of published videos is used as training data. Last, the prediction with expert advice method is used to update the training set, and to gain insight into how the predictor output will deviate from the best expert prediction, we address the concept of expected cumulative loss and derive the analytical expression for its upper bound. Extensive simulation results are shown to gain insight into our proposed system subject to different factors, such as network size, cache capacity, and user’s preference profile. In summary, we show that applying intelligence-based content-aware proactive caching is an efficient approach to significantly improving the operation of cellular networks in the future.</P>
Nguyen Duc Anh,Pham Van Thanh,Doan Tu Lap,Nguyen Tuan Khai,Tran Van An,Tran Duc Tan,Nguyen Huu An,Dang Nhu Dinh 한국인터넷정보학회 2022 KSII Transactions on Internet and Information Syst Vol.16 No.2
Forest fires inflict great losses of human lives and serious damages to ecological systems. Hence, numerous fire detection methods have been proposed, one of which is fire detection based on sensors. However, these methods reveal several limitations when applied in large spaces like forests such as high cost, high level of false alarm, limited battery capacity, and other problems. In this research, we propose a novel forest fire detection method based on image processing and correlation coefficient. Firstly, two fire detection conditions are applied in RGB color space to distinguish between fire pixels and the background. Secondly, the image is converted from RGB to YCbCr color space with two fire detection conditions being applied in this color space. Finally, the correlation coefficient is used to distinguish between fires and objects with fire-like colors. Our proposed algorithm is tested and evaluated on eleven fire and non-fire videos collected from the internet and achieves up to 95.87% and 97.89% of F-score and accuracy respectively in performance evaluation.
Nguyen, Tuan Lam,Pham, Thi Quynh Nga,Hoang, Van Minh,Kim, Bao Giang,Phan, Thi Hai,Doan, Thu Huyen,Nguyen, Thuy Linh,Duong, Khanh Van,Luong, Ngoc Khue Asian Pacific Journal of Cancer Prevention 2016 Asian Pacific journal of cancer prevention Vol.17 No.no.sup1
Second-hand tobacco smoke (SHS) exposure at home, especially among children, is a serious issue in Viet Nam. During the past decade, much effort has been taken for tobacco control in the country, including various prgorammes aiming to reduce SHS exposure among adults and children. This article analysed trends and factors associated with SHS exposure at home among school children aged 13-15 in Viet Nam, using the Global Youth Tobacco Surveys conducted in 2007 and 2014. Descriptive and inferential statistical methods with logistic regression were applied. Overall, there was a significant reduction in the level of exposure, from 58.5% (95%CI: 57.6-59.3) in 2007 to 47.1% (95%CI: 45.4-48.8) in 2014. Of the associated factors, having one or both parents smoking was significantly associated with the highest odds of SHS exposure at home (OR=5.0; 95%CI: 4.2-6.1). Conversely, having a mother with a college or higher education level was found to be a protective factor (OR=0.5; 95%CI: 0.3-0.8).
Nguyen, Thanh Huong,Nguyen, Trung Kien,Kim, Bao Giang,Hoang, Van Minh,Phan, Thi Hai,Doan, Thu Huyen,Luong, Ngoc Khue,Nguyen, Thuy Linh,Nguyen, Tuan Lam,Pham, Thi Quynh Nga Asian Pacific Journal of Cancer Prevention 2016 Asian Pacific journal of cancer prevention Vol.17 No.no.sup1
Studies have shown that smoking is a learnt behavior, often initiated during adolescence. This paper aims to describe tobacco-related knowledge, attitude and associations among school adolescents aged 13-15 with exposure to anti-smoking information. Using data from the Global Youth Tobacco Survey (GYTS) in Viet Nam, 2014, knowledge was measured through 4 questions about tobacco use, and attitude was assessed through 3 questions on personal, social and environmental aspects. Students giving most anti-tobacco responses to all questions were considered as having correct knowledge or appropriate attitude or both. Access to anti-smoking information was determined by exposure to any media messages on tobacco control during the past 30 days and teaching in school about the danger of tobacco use during the past 12 months. A substantial percentage of students thought that being near others who smoke might be harmful to them and smoking is harmful to health (89.4% and 89.6% respectively). However, only 46.4% reported that it is definitely difficult to quit smoking and 66.9% thought that smoking for only 1 or 2 years, once stopped, is harmful to health. Slightly more than half of the respondents reported appropriate attitude that young smokers have fewer friends than others and smoking makes them less attractive and less comfortable at social events. Noticing anti-smoking messages in the media together with having lessons in school about the dangers of tobacco substantially increased the likelihood of having correct knowledge, appropriate attitude and both. Despite relatively high awareness about smoking harms, effective educational communication is still highly needed to improve the level of comprehensive knowledge and an appropriate attitude regarding tobacco use.
The Role of Zn Doping on the Catalytic Activity of the Nanoparticle Perovskite La0.7Sr0.3MnO3
Tran Thi Minh Nguyet,Nguyen Quang Huan,Tran Que Chi,Do The Chan,Nguyen Doan Thai,Nguyen Cong Trang,Luu Tien Hung,Le Van Tiep,Nguyen Van Qui 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.52 No.5
The nanometer complex oxide La0:7Sr0.3Mn0.6Zn0.₄O₃ was prepared by using a Sol-Gel method with citric acid as a ligand. The in uence of Zn doping of La0.7Sr0.₃MnO₃ on the structure, the morphology, the surface properties and on the catalytic activity of material was studied by using X-ray diraction (XRD), transmission electron microscopy (TEM), a high-resolution images and selected area electron diraction (SAED), physical adsorption and temperature programmed surface reaction (TPSR) methods. The results showed that perovskite La0:7Sr0:3Mn0:6. Zn0.₄O₃ could well catalyse propene oxidation in the temperature range 190 { 280 ℃, which was reduced to 100 { 120 ℃ for catalyst La1-χSrχMnO₃ The nanometer complex oxide La0:7Sr0.3Mn0.6Zn0.₄O₃ was prepared by using a Sol-Gel method with citric acid as a ligand. The in uence of Zn doping of La0.7Sr0.₃MnO₃ on the structure, the morphology, the surface properties and on the catalytic activity of material was studied by using X-ray diraction (XRD), transmission electron microscopy (TEM), a high-resolution images and selected area electron diraction (SAED), physical adsorption and temperature programmed surface reaction (TPSR) methods. The results showed that perovskite La0:7Sr0:3Mn0:6. Zn0.₄O₃ could well catalyse propene oxidation in the temperature range 190 { 280 ℃, which was reduced to 100 { 120 ℃ for catalyst La1-χSrχMnO₃
Artocarpus nigrifolius: Cytotoxic and Antibacterial Constituents
Hoi, Tran Minh,Anh, Ha Van,Huong, Nguyen Thi Thanh,Tuyen, Nguyen Van,Anh, Le Thi Tu,Tra, Nguyen Thanh,Cham, Ba Thi,Ha, Nguyen Thi Thu,Linh, Pham Thuy,Tien, Doan Duy,Kiem, Phan Van,Ban, Ninh Khac,Kukha The Korean Society for Applied Biological Chemistr 2013 Applied Biological Chemistry (Appl Biol Chem) Vol.56 No.6
Six known compounds including ${\alpha}$-amyrin 3-acetate (1), ${\beta}$-sitosterol (2), betulinic acid (3), friedelan-3-one (4), artochamin B (5), and 2-C-methyl-D-erythritol 4-O-${\alpha}$-D-glucopyranoside (6) were isolated from the stem barks and leaves of Artocarpus nigrifolius (Moraceae) for the first time. Their structures were identified by spectroscopic methods as well as comparison with literatures. Cytotoxicity and antibacterial activity of 1-6 were evaluated. Results showed that artochamin B (5) possessed the highest cytotoxicity towards MCF7, Lu, HepG2, and KB cell lines with $IC_{50}$ values of 4.59, 20.00, 3.60, and $1.18{\mu}g/mL$, respectively. It also inhibited the growth of Gram-positive bacteria (Bacillus subtilis, Staphylococcus aureus), whereas inactive on the growth of both Gram-negative bacteria and yeast.
Artocarpus nigrifolius: Cytotoxic and Antibacterial Constituents
Tran Minh Hoi,김영호,Ha Van Anh,Nguyen Thi Thanh Huong,Nguyen Van Tuyen,Le Thi Tu Anh,Nguyen Thanh Tra,Ba Thi Cham,Nguyen Thi Thu Ha,Pham Thuy Linh,Doan Duy Tien,Phan Van Kiem,Ninh Khac Ban,Lidziya Kukha 한국응용생명화학회 2013 Applied Biological Chemistry (Appl Biol Chem) Vol.56 No.6
Six known compounds including α-amyrin 3-acetate (1), β-sitosterol (2), betulinic acid (3), friedelan-3-one (4),artochamin B (5), and 2-C-methyl-D-erythritol 4-O-α-D-glucopyranoside (6) were isolated from the stem barks and leaves of Artocarpus nigrifolius (Moraceae) for the first time. Their structures were identified by spectroscopic methods as well as comparison with literatures. Cytotoxicity and antibacterial activity of 1-6 were evaluated. Results showed that artochamin B (5)possessed the highest cytotoxicity towards MCF7, Lu, HepG2,and KB cell lines with IC50 values of 4.59, 20.00, 3.60, and 1.18μg/mL, respectively. It also inhibited the growth of Gram-positive bacteria (Bacillus subtilis, Staphylococcus aureus), whereas inactive on the growth of both Gram-negative bacteria and yeast.