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Upconversion luminescence of Gd2O3:Er3+and Gd2O3:Er3+/silica nanophosphors fabricated by EDTA combustion method

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Journal of Rare Earths 2019年第11期37卷 1126-1131页

作者： Le Quoc Minh tran Kim Anh nguyen Duy Hung Pham Thi Minh Chau nguyen Thi Quy Hai Ho Van Tuyen Vu Thi Thai Ha Vu Duc Tu Wieslaw Strek Institute of Theoretical and Applied Research Duy Tan UniversityDa Nang 55000Viet Nam Advanced Institute for Science and Technology Hanoi University of Science and Technology1 Dai Co VietHai Ba TrungHanoiViet Nam Institute of Materials Science Vietnam Academy of Science and Technology18 Hoang Quoc Viet RoadCau Giay DistrictHanoiViet Nam Institute of Low Temperature and Structure Research Polish Academy of Science 2 OkolnaWroclawPoland

Gd2O3:Er^3+nanophosphors were fabricated by the combustion method in presence of Na2 ethylene diamine tetra acetic acid(EDTA-Na2)as fuel at not high temperature(≤350℃)within a very short time of 5 *** added concentration of Er^3+ions in Gd2O3 matrix was changed from 0.5 mol%to 5.0 mol%.The X-ray diffraction pattern of samples indicates the monoclinic structure of Gd2O3:Er^3+.The morphology and chemical composition analysis of the Gd2O3:Er^3+samples are characterized by a field emission scanning electron microscope(FESEM)and a Fourier-transform infrared spectrometer(FTIR).The photoluminescence(PL),photo luminescence excitation(PLE)and upconversion(UC)at room temperature of the prepared materials with different concentrations of Er^3+were *** PL of Gd2O3:Er^3+nanomaterials are shown in visible at 545,594,623,648,688 nm under excitation at 275 *** emission bands from transitions of Er^3+from 2P3/2 to 4F9/2 are observed,UC luminescent spectra of the Gd2O3:Er^3+/silica nanocomposites under 976 nm excitation show the bands at 548 and 670 *** influence of excitation power at 980 nm for transitions were measured and *** results indicate that the upconversion process of Gd2O3:Er^3+/silica is two photons absorption *** low temperature dependence of UC luminescent intensities of the main bands of Gd2O3:Er^3+was investigated towards development of a nanotemperature sensor in the range of 10-300 K.

关键词： Upconversion luminescence Gd2O3:Er3+ Gd2O3:Er3+/silica Nanophosphors EDTA combustion Rare earths

Picture-Neutrosophic Trusted Safe Semi-Supervised Fuzzy Clustering for Noisy Data

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Computer Systems Science & Engineering 2023年第8期46卷 1981-1997页

作者： Pham Huy Thong Florentin Smarandache Phung The Huan tran Manh Tuan tran Thi Ngan Vu Duc Thai nguyen Long Giang Le Hoang Son Graduate University of Science and Technology Vietnam Academy of Science and TechnologyHanoi100000Vietnam Institute of Information Technology Vietnam Academy of Science and TechnologyHanoi100000Vietnam VNU Information Technology Institute Vietnam National UniversityHanoi100000Vietnam Department of Mathematics University of New MexicoGallup87301New MexicoUSA University of Information and Communication Technology Thai Nguyen UniversityThai Nguyen250000Vietnam Faculty of Computer Science and Engineering Thuyloi UniversityHanoi100000Vietnam

Clustering is a crucial method for deciphering data structure and producing new *** to its significance in revealing fundamental connections between the human brain and events,it is essential to utilize clustering for cognitive *** with noisy data caused by inaccurate synthesis from several sources or misleading data production processes is one of the most intriguing clustering *** data can lead to incorrect object recognition and *** research aims to innovate a novel clustering approach,named Picture-Neutrosophic Trusted Safe Semi-Supervised Fuzzy Clustering(PNTS3FCM),to solve the clustering problem with noisy data using neutral and refusal degrees in the definition of Picture Fuzzy Set(PFS)and Neutrosophic Set(NS).Our contribution is to propose a new optimization model with four essential components:clustering,outlier removal,safe semi-supervised fuzzy clustering and partitioning with labeled and unlabeled *** effectiveness and flexibility of the proposed technique are estimated and compared with the state-of-art methods,standard Picture fuzzy clustering(FC-PFS)and Confidence-weighted safe semi-supervised clustering(CS3FCM)on benchmark UCI *** experimental results show that our method is better at least 10/15 datasets than the compared methods in terms of clustering quality and computational time.

关键词： Safe semi-supervised fuzzy clustering picture fuzzy set neutrosophic set data partition with noises fuzzy clustering

Effects of the urban heat island and climate change on the growth of Khaya senegalensis in Hanoi,Vietnam

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Forest Ecosystems 2018年第4期5卷 516-529页

作者： Astrid Moser-Reischl Enno Uhl Thomas Rotzer Peter Biber tran van Con nguyen Thanh Tan Hans Pretzsch Chair for Forest Growth and Yield Science Center of Life and Food Sciences WelhenstephanTechnical University MunichHans-Carl-von-Carlowitz-Platz 285354 FreisingGermany Vietnamese Academy of Forest Sciences Dong Ngac CommuneTu Liem DistrictHanoiVietnam Tay nguyen University 567 Le Duan StreeBuon Ma Thuot CityDak La ProvinceVietnam

Background: Recent projections expect that Vietnam will be affected most severely by climate change with higher temperatures, more precipitation and rising sea levels. Especially increased temperatures will worsen the situations in cities, amplifying the urban heat island effect. Green infrastructures, i.e. urban trees are a common rtool to improve the urban micro-climate for humans. Vital and well growing trees provide greatest benefits such as evaporative cooling, shading, air filtering and carbon storage. However, urban tree growth is often negatively affected by urban growing conditions such as high soil sealing with compacted tree pits providing small growing spaces with limited water, nutrient and oxygen supply, further warm temperatures and high pollution emissions. This study analyzed the growth of urban and rural African mahogany(Khaya senegalensis(Desr.) A. Juss.) trees in the city of Hanoi, Vietnam and the effects of the surrounding climate conditions on tree ***: The results showed that rural African mahogany trees grew better than trees situated in the city center, which is contrary to other results on tree growth of temperate and subtropical cities worldwide. Moreover tree growth was similar regardless of the time of growth. Other results regarding stem growth of African mahogany located in different areas of Hanoi(east, west, north, city center) revealed a better growth in the northern and western outskirts of the city compared to the growth of trees in the city ***: African mahogany trees in the urban centers of Hanoi showed a decreased growth compared to rural trees,which was likely induced by a low ground-water level and high pollution rates. In view of climate change and global warming, the decreased tree growth in the city center may also affect tree service provision such as shading and cooling. Those climate mitigation solutions are strongly needed in areas severely affected by climate change and global warming such as

关键词： African mahogany Dendrochronology Ecosystem services Urban tree growth

Invariant Lighting Hand Posture Classification

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Invariant Lighting Hand Posture Classification

Spatio-Temporal Analysis of Drought in the North-Eastern Coastal Region of Vietnam Using the Standardized Precipitation Index (SPI)

The 2010 IEEE International Conference on Progress in Informatics and Computing

作者： Thi-Thanh-Hai tran Thi-Thanh-Mai nguyen MICA International Research Center Hanoi University of Science and Technology VietNam

ISBN: (纸本)9781424467860

＜正＞Hand posture classification is a key problem for many human computer interaction ***,this is not a simple *** this paper,we propose to decompose the hand posture classification problem into 2 *** the first step,we detect skin regions using a very fast algorithm of color segmentation based on thresholding *** segmentation is robust to lighting condition thank to a step of color normalization using neural *** the second step, each skin region will be classified into one of hand posture class using Cascaded Adaboost *** contributions of this paper are:（i） By applying a step of color normalization,the posture classification rate is significantly improved under varying lighting condition;（ii） The cascaded Adaboost technique has been studied for the problem of face detection（2 classes）.In this paper, it will be studied and evaluated in more detail in a problem of classification of hand postures（multi-classes）.

关键词： Hand posture classification Cascaced Adaboost Color normalization Neural network Lighting invariance

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Atmospheric and Climate Sciences 2023年第2期13卷 175-200页

作者： nguyen Van Tuan nguyen Van hieu nguyen Khac Bang Pham Hoang Hai nguyen Khanh Van Le Vinh Ha tran Thi Hoa Lê Trọng Hiếu Institute of Water Resources Planning Hanoi Vietnam Institute of Environment and Public Health Vietnam Union of Science and Technology Associations Hanoi Vietnam Thai Binh University Thai Binh Vietnam Faculty of Electronics and Telecommunications Electric Power University Hanoi Vietnam

Spatio-temporal analysis of drought provides valuable information for drought management and damage mitigation. In this study, the Standardized Precipitation Index at the time scale of 6 months (SPI-6) is selected to reflect drought conditions in the North-Eastern coastal region of Vietnam. The drought events and their characteristics from 1981 to 2019 are detected at 9 meteorological stations and 10 Chirps rainfall stations. The spatio-temporal variation of drought in the study region is analyzed on the basis of the number, duration, severity, intensity, and peak of the detected drought events at the 19 stations. The results show that from 1981 to 2019 the drought events mainly occurred with 1-season duration and moderate intensity and peak. The number, duration, severity, and peak of the drought events were the greatest in the period 2001-2010 and were the smallest in the period 2011-2019. Among the 19 stations, the drought duration tends to decrease at 11 stations, increase at 7 stations, and has a slight variant at 1 station;the drought severity tends to decrease at 14 stations, increase at 4 stations, and has not a significant trend at 1 station;the drought intensity tends to decrease at 17 stations, increase at 1 station, and has a slight variant at 1 station;and the drought peak tends to decrease at 18 stations and increase at 1 station.

关键词： Spatio-Temporal Analysis of Drought Standardized Precipitation Index (SPI) Drought Characteristics

Improved flood susceptibility mapping using a best first decision tree integrated with ensemble learning techniques

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Geoscience Frontiers 2021年第3期12卷 333-342页

作者： Binh Thai Pham Abolfazl Jaafari tran Van Phong Hoang Phan Hai Yen tran Thi Tuyen Vu Van Luong Huu Duy nguyen Hiep Van Le Loke Kok Foong University of transport Technology Ha Noi 100000Viet Nam Research Institute of Forests and Rangelands Agricultural ResearchEducation and Extension Organization(AREEO)TehranIran Institute of Geological Sciences Vietnam Academy of Sciences and Technology84 Chua Lang StreetDong daHa NoiViet Nam Department of Geography School of Social EducationVinh UniversityViet Nam Department of Resource and Environment Management School of Agriculture and ResourcesVinh UniversityViet Nam Faculty of Geography VNU University of Science334 Nguyen TraiHa NoiViet Nam Institute of Research and Development Duy Tan UniversityDa Nang 550000Viet Nam Department for Management of Science and Technology Development Ton Duc Thang UniversityHo Chi Minh CityViet Nam Faculty of Civil Engineering Ton Duc Thang UniversityHo Chi Minh CityViet Nam

Improving the accuracy of flood prediction and mapping is crucial for reducing damage resulting from flood *** this study,we proposed and validated three ensemble models based on the Best First Decision Tree(BFT)and the Bagging(Bagging-BFT),Decorate(Bagging-BFT),and Random Subspace(RSS-BFT)ensemble learning techniques for an improved prediction of flood susceptibility in a spatially-explicit manner.A total number of 126 historical flood events from the Nghe An Province(Vietnam)were connected to a set of 10 flood influencing factors(slope,elevation,aspect,curvature,river density,distance from rivers,flow direction,geology,soil,and land use)for generating the training and validation *** models were validated via several performance metrics that demonstrated the capability of all three ensemble models in elucidating the underlying pattern of flood occurrences within the research area and predicting the probability of future flood *** on the Area Under the receiver operating characteristic Curve(AUC),the ensemble Decorate-BFT model that achieved an AUC value of 0.989 was identified as the superior model over the RSS-BFT(AUC=0.982)and Bagging-BFT(AUC=0.967)models.A comparison between the performance of the models and the models previously reported in the literature confirmed that our ensemble models provided a reliable estimate of flood susceptibilities and their resulting susceptibility maps are trustful for flood early warning systems as well as development of mitigation plans.

关键词： Machine learning Ensemble learners Hybrid modeling

Fuzzy Feedback Control for Electro-Hydraulic Actuators

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Intelligent Automation & Soft Computing 2023年第5期36卷 2441-2456页

作者： Tan nguyen Van Huy Q.tran Vinh Xuan Ha Cheolkeun Ha Phu Huynh Minh School of Engineering-Technology Thu Dau Mot UniversityThu Dau Mot City590000Vietnam Faculty of Engineering-Technology Nguyen Tat Thanh UniversityHo Chi Minh City754000Vietnam Hue Industrial College Hue City530000Vietnam Robotics and Mechatronics Lab University of UlsanUlsan City44610Korea

Electro-hydraulic actuators(EHA)have recently played a signiﬁcant role in modern industrial applications,especially in systems requiring extremely high *** can be explained by EHA’s ability to precisely control the position and force through advanced sensors and innovative control *** of the promising approaches to improve control accuracy for EHA systems is applying classical to modern control algorithms,in which the proportional–inte-gral–derivative(PID)algorithm,fuzzy logic controller,and a hybrid of these methods are popular *** this paper,we developed a novel version of the fuzzy control algorithm and linear feedback control method,namely fuzzy lin-ear feedback control,to improve the control *** achieve the highest performance,weﬁrst designed a mathematical EHA model based on the Matlab/Simulink software packages thanks to the selected parameters,which are similar to a real EHA ***,we respectively applied PID,fuzzy PID(FPID),and fuzzy linear feedback control(FLFC)before comparing them to have a full view of the outstanding advantages of the proposed *** simulation results showed that the proposed FLFC algorithm is approximately 99%and 77%super-ior in performance to the PID and feedback control algorithms,respectively.

关键词： Electro-hydraulic actuator fuzzy PID feedback control

Differential Mortality Outcomes in Real-world Patients with Lean,Nonobese,and Obese Nonalcoholic Fatty Liver Disease

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Journal of Clinical and translational Hepatology 2023年第7期11卷 1448-1454页

作者： Vy H.nguyen Audrey Ha Nicholas Ajit Rouillard Richard hieu Le Ashley Fong Surya Gudapati Jung Eun Park Mayumi Maeda Scott Barnett Ramsey Cheung Mindie H.nguyen Division of Gastroenterology and Hepatology Stanford University Medical CenterPalo AltoCAUSA Harvard Medical School BostonMAUSA William Carey University College of Osteopathic Medicine HattiesburgMSUSA Washington University St LouisMOUSA Division of Gastroenterology and Hepatology Palo Alto Veterans Affairs Medical CenterPalo AltoCAUSA Department of Epidemiology and Population Health Stanford University Medical CenterPalo AltoCAUSA

Background and Aims:Nonalcoholic fatty liver disease(NAFLD)is commonly associated with obesity but can de-velop in normal-weight people(lean NAFLD).We compared outcomes in lean,overweight,and obese ***:This retrospective chart review included patients at Stanford University Medical Center with NAFLD confirmed by imaging between March 1995 and December ***,overweight,and obese patients had body mass index of25.0 and23.0 and≥27.5 for overweight and obese Asian ***:A total of 9061 lean(10.2%),overweight(31.7%),and obese(58.1%)patients were *** patients were 5 years older than obese patients(53±17.4 VS.48.7±±15.1 years),more were female(59.6%vs.55.2%),white(49.1%vs.46.5%),had NASH(29.2%VS.22.5%),cirrhosis(25.3%.Vs.19.2%),or nonliver cancer(25.3%Vs.18.3%).Fewer had diabetes(21.7%Vs.35.8%)or metabolic comorbidi-ties(all p<0.0001).Lean NAFLD patients had liver-related mortality similar to other groups but higher overall(p=0.01)and nonliver-related(p=0.02)*** multivariable model adjustment for covariates,differences between lean and obese NAFLD in liver-related,nonliver-related,and over-all mortality(adjusted hazard ratios of 1.34,1.00,and 1.32;p=0.66,0.99,and 0.20,respectively)were not ***:Lean NAFLD had fewer metabolic comorbidi-ties but similar adverse or worse outcomes,suggesting that it is not *** providers should provide the same level of care and intervention as for overweight and obese NAFLD.

关键词： Chronic liver disease Cirrhosis Lean NAFLD Liver-related mortality NAFLD NASH Nonliver cancer mortality

Anti-inflammatory effects of fatty acids isolated from Chromolaena odorata

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Asian Pacific Journal of Tropical Medicine 2011年第10期4卷 760-763页

作者： tran Thi Hong Hanh Dan Thi Thuy Hang Chau Van Minh nguyen Tien Dat Institute of Marine Biochemistry Vietnam Academy of Science and Technology(VAST)

Objective:To identify inhibitors of nitric oxide production and NF-κB activity from Chromolaena odorata（***）.Methods:The compounds isolated from the aerial parts of *** by bioassay-guided fractionation were investigated for their inhibitory effects on the NO production and NF-κB activity in LPS-stimulated RAW264.7 ***:Six fatty acids （S）-coriolic acid（1）,（S）-coriolic acid methyl ester（2）,（5）-15,16-didehydrocoriolic acid（3）,（S）- 15,16-didehydrocoriolic acid methyl ester（4）,linoleamide（5） and linolenamide（6） were isolated. All compounds inhibited the NO production at concentrations consistent with those required for NF-κB *** 2 was the most active with the IC50 values of 5.22 and 5.73μM. The addition of a double bond in the fatty chain decreased the inhibitory effects while the methyl esterification increased the ***:The fatty acid components in *** with NF-κB inhibitory activity could explain the anti-inflammation property of this plant in traditional *** study could also contribute to the better use of *** for human health care.

关键词： Chromolaena odorata Asteraceae Fatty acid NF-κB Nitric oxide