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

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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

Xanthine oxidase inhibitors from Archidendron clypearia(Jack.) I.C. Nielsen: Results from systematic screening of Vietnamese medicinal plants

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Asian Pacific Journal of Tropical Medicine 2017年第6期10卷 619-626页

作者： Nguyen Thuy Duong Pham Duc Vinh Phuong Thien Thuong Nguyen Thi Hoai le Nguyen Thanh Tran The Bach Nguyen Hai Nam Nguyen hoang Anh Department of Pharmacology Hanoi University of Pharmacy Department of Pharmaceutical Analysis and Standardization National Institute of Medicinal Materials Department of Pharmacognosy Hue University of Medicine and Pharmacy Institute of Marine Biochemistry Vietnam Academy of Science and Technology Institute of Ecology and Biological Resources Vietnam Academy of Science and Technology Department of Medicinal Chemistry Hanoi University of Pharmacy

Objective: To screen Vietnamese medicinal plants for xanthine oxidase(XO) inhibitory activity and to isolate XO inhibitor(s) from the most active plant. Methods: The plants materials were extracted by methanol. The active plant materials were fractionated using different organic solvents, including n-hexane, ethyl acetate, and n-butanol. Bioassay-guided fractionation and column chromatography were used to isolate compounds. The compounds structures were elucidated by analysis of spectroscopic data, including IR, MS, and NMR. Results: Three hundreds and eleven methanol extracts(CME) belonging to 301 Vietnamese herbs were screened for XO inhibitory activity. Among these plants, 57 extracts displayed XO inhibitory activity at 100 μg/m L with inhibition rates of over 50%. The extracts of Archidendron clypearia, Smilax poilanei, Linociera ramiflora and Passiflora foetida exhibited the greatest potency with IC_(50) values below 30 μg/m L. Chemical study performed on the extract of Archidendron clypearia resulted in the isolation of six compounds, including 1-octacosanol, docosenoic acid, daucosterol, methyl gallate, quercitrin and(-)-7-O-galloyltricetiflavan. The compound(-)-7-O-galloyltricetiflavan showed the most potent XO inhibitory activity with an IC_(50) value of 25.5 μmol/L. Conclusions: From this investigation, four Vietnamese medicinal plants were identified to have XO inhibitory effects with IC_(50) values of the methanol extracts below 30 μg/m L. Compound(-)-7-O-galloyltricetiflavan was identified as an XO inhibitor from Archidendron clypearia with IC_(50) value of 25.5 μmol/L.

关键词： Xanthine oxidase Inhibitor Medicinal plants Vietnam

Genetic variants of interferon regulatory factor 5 associated with chronic hepatitis B infection

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World Journal of Gastroenterology 2018年第2期24卷 248-256页

作者： Bui Tien Sy Nghiem Xuan Hoan hoang Van Tong Christian G Meyer Nguyen Linh Toan le Huu Song Claus-Thomas Bock Thirumalaisamy P Velavan Vietnamese-German Center of Excellence in Medical Research HanoiVietnam Institute of Clinical Infectious Diseases 108 Military Central HospitalHanoiVietnam Institute of Tropical Medicine University of TübingenTübingen 72074Germany Department of Infectious Diseases Robert Koch InstituteBerlin 13302Germany Department of Pathophysiology Vietnam Military Medical UniversityHanoiVietnam

AIM To investigate possible effects of IRF5 polymorphisms in the 3' UTR region of the IFR5 locus on susceptibilityto hepatitis B virus(HBV) infection and progression of liver diseases among clinically classified Vietnamese *** Four IFR5 SNPs(rs13242262 A/T, rs77416878 C/T, rs10488630 A/G, and rs2280714 T/C) were genotyped in clinically classified HBV patients [chronic hepatitis B(CHB). n = 99; liver cirrhosis(LC), n = 131; hepatocellular carcinoma(HCC), n = 149] and in 242 healthy controls by direct sequencing and Taq Man realtime PCR assays. RESULTS Comparing patients and controls, no significant association was observed for the four IFR5 variants. However, the alleles rs13242262 T and rs10488630 G contributed to an increased risk of liver cirrhosis(LC vs CHB: OR = 1.5, 95%CI: 1.1-2.3, adjusted P = 0.04; LC vs CHB: OR = 1.7, 95%CI: 1.1-2.6, adjusted P = 0.019). Haplotype IRF5*TCGT constructed from 4 SNPs was observed frequently in LC compared to CHB patients(OR = 2.1, 95%CI: 1.2-3.3, adjusted P = 0.008). Haplotype IRF5*TCAT occurred rather among CHB patients than in the other HBV patient groups(LC vs CHB: OR = 0.4, 95%CI: 0.2-0.8, adjusted P = 0.03; HCC vs CHB: OR = 0.3, 95%CI: 0.15-0.7, adjusted P = 0.003). The IRF5*TCAT haplotype was also associated with increased levels of ALT, AST and bilirubin. CONCLUSION Our study shows that IFR5 variants may contribute as a host factor in determining the pathogenesis in chronic HBV infections.

关键词： hepatitis B virus infection Liver diseases IRF5 IFR5 polymorphisms IFR5 haplotypes

Locally weighted learning based hybrid intelligence models for groundwater potential mapping and modeling: A case study at Gia Lai province, Vietnam

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Geoscience Frontiers 2021年第5期12卷 54-68页

作者： hoang Phan Hai Yen Binh Thai Pham Tran Van Phong Duong Hai Ha Romulus Costache Hiep Van le Huu Duy Nguyen Mahdis Amiri Nguyen Van Tao Indra Prakash Department of Geography School of Social Sciences EducationVinh University182 Le DuanVinhNghe AnVietnam University of Transport Technology Hanoi 100000Viet Nam Institute of Geological Sciences Vietnam Academy of Science and Technology(VAST)84 Chua LangDong DaHanoiViet Nam Institute for Water and Environment Hanoi 100000Viet Nam Research Institute of the University of Bucharest 90-92 Sos.Panduri5th DistrictBucharestRomania National Institute of Hydrology and Water Management București-Ploiești Road97E1st District013686 BucharestRomania Faculty of Geography VNU University of ScienceVietnam National University334 Nguyen TraiHanoi 100000Viet Nam Department of Watershed&Arid Zone Management Gorgan University of Agricultural Sciences&Natural ResourcesGorgan ***Iran DDG(R)Geological Survey of India Gandhinagar 382010India

The groundwater potential map is an important tool for a sustainable water management and land use planning,particularly for agricultural countries like *** this article,we proposed new machine learning ensemble techniques namely AdaBoost ensemble(ABLWL),Bagging ensemble(BLWL),Multi Boost ensemble(MBLWL),Rotation Forest ensemble(RFLWL)with Locally Weighted learning(LWL)algorithm as a base classifier to build the groundwater potential map of Gia Lai province in *** this study,eleven conditioning factors(aspect,altitude,curvature,slope,Stream Transport Index(STI),Topographic Wetness Index(TWI),soil,geology,river density,rainfall,land-use)and 134 wells yield data was used to create training(70%)and testing(30%)datasets for the development and validation of the *** statistical indices were used namely Positive Predictive Value(PPV),Negative Predictive Value(NPV),Sensitivity(SST),Specificity(SPF),Accuracy(ACC),Kappa,and Receiver Operating Characteristics(ROC)curve to validate and compare performance of *** show that performance of all the models is good to very good(AUC:0.75 to 0.829)but the ABLWL model with AUC=0.89 is the *** the models applied in this study can support decision-makers to streamline the management of the groundwater and to develop economy not only of specific territories but also in other regions across the world with minor changes of the input parameters.

关键词： Locally weighted learning Hybrid models Groundwater potential GIS Vietnam

On the Alternate Direction Implicit (ADI) Method for Solving Heat Transfer in Composite Stamping

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Materials Sciences and Applications 2017年第1期8卷 37-63页

作者： Arthur levy Duc Anh hoang Steven le Corre Laboratoire de Thermique et Energie de Nantes La Chantrerie Rue Christian Pauc Nantes France IRT Jules Verne Chemin du Chaffault Bouguenais France

Thermostamping of thermoplastic matrix composites is a process where a preheated blank is rapidly shaped in a cold matching mould. Predictive modelling of the main physical phenomena occurring in this process requires an accurate prediction of the temperature field. In this paper, a numerical method is proposed to simulate this heat transfer. The initial three-dimensional heat equation is handled using an additive decomposition, a thin shell assumption, and an operator splitting strategy. An adapted resolution algorithm is then presented. It results in an alternate direction implicit decomposition: the problem is solved successively as a 2D surface problem and several one-dimensional through thickness problems. The strategy was fully validated versus a 3D calculation on a simple test case and the proposed strategy is shown to enable a tremendous calculation speed up. The limits of applicability of this method are investigated with two parametric studies, one on the thickness to width ratio and the other one on the effect of curvature. These conditions are usually fulfilled in industrial cases. Finally, even though the method was developed under linear assumption (constant material properties), the strategy validity is extended to multiply, temperature dependant (nonlinear) case using an industrial test case. Because of the standard methods involved, the proposed ADI method can readily be implemented in existing software.

关键词： Thin Plates Alternate Direction Implicit Shell Theory Operator Splitting In-Plane Variations

Buckling Analysis of FG Porous Truncated Conical Shells Resting on Elastic Foundations in the Framework of the Shear Deformation Theory

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Advances in Applied Mathematics and Mechanics 2022年第1期14卷 218-247页

作者： le Kha Hoa Bui Gia Phi Do Quang Chan Dang Van Hieu Military Academy of Logistics HanoiVietnam Department of Technical Fundamental University of Transport Technology54 Trieu Khuc9 Thanh XuanHanoiVietnam Department of Mechanical Engineering and Mechatronics PHENIKAA UniversityHanoi 12116Vietnam PHENIKAA Research and Technology Institute(PRATI) A&A Green Phoenix Group JSCNo.167 Hoang NganTrung HoaCau GiayHanoi 11313Vietnam Thainguyen University of Technology ThainguyenVietnam

In this article,an analytical method is proposed to analyze of the linear buckling behavior of the FG porous truncated conical shells subjected to a uniform axial compressive load and resting on the Pasternak elastic *** material properties including Young’s modulus,shear modulus and density are assumed to vary in the thickness *** types of FG porous distributions including symmetric porosity distribution,non-symmetric porosity and uniform porosity distribution are *** governing equations of the FG porous truncated conical shells are obtained by using the first-order shear deformation theory(FSDT).With the help of the Galerkin method,the expressions for critical buckling loads are obtained in closed *** reliability of the obtained results is verified by comparing the present solutions with the published ***,the numerical results show the effects of shell characteristics,porosity distribution,porosity coefficient,and elastic foundation on the critical buckling load.

关键词： Buckling truncated conical shells first order shear deformation theory porous materials elastic foundations

Ecoregional variations of aboveground biomass and stand structure in evergreen broadleaved forests

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Journal of Forestry Research 2020年第5期31卷 1713-1722页

作者： Tran Van Do Mamoru Yamamoto Osamu Kozan Vo Dai Hai Phung Dinh Trung Nguyen Toan Thang Lai Thanh Hai Vu Thanh Nam Trieu Thai Hung hoang Van Thang Tran Duc Manh Cao Chi Khiem Vu Tien Lam Nguyen Quang Hung Tran hoang Quy Pham Quang Tuyen Trinh Ngoc Bon Nguyen Thi Thu Phuong Ninh Viet Khuong Nguyen Van Tuan Dang Thi Hai Ha Tran Hai Long Dang Van Thuyet Dang Thinh Trieu Nguyen Van Thinh Tran Anh Hai Duong Quang Trung Nguyen Van Bich Dinh Hai Dang Pham Tien Dung Nguyen Huy hoang le Thi Hanh Phan minh Quang Nguyen Thi Thuy Huong hoang Thanh Son Nguyen Thanh Son Nguyen Thi Van Anh Nguyen Thi Hoai Anh Pham Dinh Sam hoang Thi Nhung hoang Van Thanh Nguyen Huu Thinh Tran Hong Van Ho Trung Luong Bui Kieu Hung Research Institute for Sustainable Humanosphere Kyoto UniversityUjiKyotoJapan Silviculture Research Institute Vietnamese Academy of Forest SciencesNorth Tu LiemHanoiVietnam Center for Southeast Asian Studies Kyoto UniversityKyotoJapan Vietnamese Academy of Forest Sciences North Tu LiemHanoiVietnam Vietnam Administration of Forestry No.2 Ngoc HaBa DinhHanoiVietnam

Biotic and abiotic factors control aboveground biomass(AGB)and the structure of forest *** study analyses the variation of AGB and stand structure of evergreen broadleaved forests among six ecoregions of Vietnam.A data set of 1731-ha plots from 52 locations in undisturbed old-growth forests was *** results indicate that basal area and AGB are closely correlated with annual precipitation,but not with annual temperature,evaporation or hours of *** area and AGB are positively correlated with trees>30 cm *** areas surveyed(52.6%)in these old-growth forests had AGB of 100–200 Mg ha^-1;5.2%had AGB of 400–500 Mg ha^-1,and 0.6%had AGB of>800 Mg ha^-*** percent of the areas surveyed had stand densities of 300–600 ***^-1,and 64%had basal areas of 20–40 m^2 ha^-*** is an important factor influencing the AGB of old-growth,evergreen broadleaved forests in *** causing the loss of large-diameter trees(e.g.,>100 cm DBH)affects AGB but may not seriously affect stand density.

关键词： Aboveground biomass Carbon storage Climatic variables Ecoregion Edaphic variables Oldgrowth forest

Optimization method to suppress background for imaging multiple planes

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Journal of Innovative Optical Health Sciences 2019年第2期12卷 24-34页

作者： Vannhu le Department of Optical Engineering le Quy Don Technical University 236 Hoang Quoc Viet Street Tu Liem DistrictHanoiVietnam State Key Laboratory of Modern Optical Instrumentation College of Optical Science and Engineering Zhejiang University Hangzhou 310027P.R.China Institute of Research and Development Duy Tan University Da Nang 550000Vietnam

3D live imaging is important for better understanding of biological *** obtain biological dynamic process,high imaging speed is *** order to improve speed in 3D live imaging,simultaneous imaging of multiple planes throughout a 3D volume has been ***,a main disadvantage of this method is the cross-talk from neighboring imaging *** this paper,we propose an optimization method to suppress background from neighboring imaging planes.A D-aperture is used to generate multiple light *** optimization method to suppress background is *** simulation results demonstrated that the proposed method can be used to suppress the effectiveness of background from neighboring light sheets.

关键词： Fluorescence microscopy imaging systems supper-resolution