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

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

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Efficient Real-Time Devices Based on Accelerometer Using Machine Learning for HAR on Low-Performance Microcontrollers

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Computers, Materials & Continua 2024年第10期81卷 1729-1756页

作者： Manh-tuyen Vi Duc-Nghia tran Vu thi Thuong Nguyen Ngoc Linh Duc-Tan tran Faculty of Electrical and Electronic Engineering Phenikaa UniversityHanoi City100000Vietnam Institute of Information Technology Vietnam Academy of Science and TechnologyHanoi City100000Vietnam Faculty of Information Technology and Communication Phuong Dong UniversityHanoi City100000Vietnam Graduate University of Sciences and Technology Vietnam Academy of Science and TechnologyHanoi City100000Vietnam International School–Vietnam National University Hanoi City100000Vietnam

Analyzing physical activities through wearable devices is a promising research area for improving health *** research focuses on the development of an affordable and real-time Human Activity Recognition(HAR)system designed to operate on low-performance *** system utilizes data from a bodyworn accelerometer to recognize and classify human activities,providing a cost-effective,easy-to-use,and highly accurate solution.A key challenge addressed in this study is the execution of efficient motion recognition within a resource-constrained *** system employs a Random Forest(RF)classifier,which outperforms Gradient Boosting Decision Trees(GBDT),Support Vector Machines(SVM),and K-Nearest Neighbors(KNN)in terms of accuracy and computational *** proposed features Average absolute deviation(AAD),Standard deviation(STD),Interquartile range(IQR),Range,and Root mean square(RMS).The research has conducted numerous experiments and comparisons to establish optimal parameters for ensuring system effectiveness,including setting a sampling frequency of 50 Hz and selecting an 8-s window size with a 40%overlap between *** was conducted on both the WISDM public dataset and a self-collected dataset,focusing on five fundamental daily activities:Standing,Sitting,Jogging,Walking,and Walking the *** results demonstrated high recognition accuracy,with the system achieving 96.7%on the WISDM dataset and 97.13%on the collected *** research confirms the feasibility of deploying HAR systems on low-performance microcontrollers and highlights the system’s potential applications in patient support,rehabilitation,and elderly care.

关键词： Accelerometer classification wearable computing activity recognition HAR

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Static and dynamic analysis of functionally graded fluidinfiltrated porous skew and elliptical nanoplates using an isogeometric approach

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Frontiers of Structural and Civil Engineering 2023年第3期17卷 477-502页

作者： tran thi Thu THUY Faculty of Mechanical Engineering Hanoi University of IndustryHanoi 100000Vietnam

The analysis of static bending and free and forced vibration responses of functionally graded fluidinfiltrated porous(FGFP)skew and elliptical nanoplates placed on Pasternak’s two-parameter elastic foundation is performed for the first time using isogeometric analysis(IGA)based on the non-uniform rational B-splines(NURBSs)basis *** types of porosity distributions affect the mechanical characteristics of materials:symmetric distribution,upper asymmetric distribution,and lower asymmetric *** stress–strain relationship for Biot porous materials was determined using the elastic *** general equations of motion of the nanoplates were established using the four-unknown shear deformation plate theory in conjunction with the nonlocal elastic theory and Hamilton’s principle.A computer program that uses IGA to determine the static bending and free and forced vibration of a nanoplate was developed on MATLAB software *** accuracy of the computational program was validated via numerical comparison with confidence *** set of programs presents the influence of the following parameters on the static bending and free and forced vibrations of nanoplates:porosity distribution law,porosity coefficient and geometrical parameters,elastic foundation,deviation angle,nonlocal coefficient,different boundary conditions,and Skempton *** numerical findings demonstrated the uniqueness of the FGFP plate’s behavior when the porosities are saturated with liquid compared with the case without *** findings of this study have significant implications for engineers involved in the design and fabrication of the aforementioned type of ***,this can form the basis for future research on the mechanical responses of the structures.

关键词： static bending free and forced vibrations nonlocal theory isogeometric analysis fluid-infiltrated porous nanoplates

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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

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Organic dye removal and recycling performances of graphene oxide-coated biopolymer sponge

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Progress in Natural Science:Materials International 2022年第5期32卷 634-642页

作者： thi Sinh Vo tran thi Bich Chau Vo School of Mechanical Engineering Sungkyunkwan University Department of Industrial Management Can Tho University

In this study, a biopolymer sponge(PS) with a crosslinked mixture of gelatin-chitosan-poly(vinyl alcohol) was dipped into graphene oxide(GO) solution to form a composite sponge(CS, GO-coated PS) by a combination of simple dip-coating and freeze-drying procedures, as a sponge-like adsorbent in organic dye removal *** morphological, chemical, crystalline, mechanical and thermal characterizations of the as-obtained sponges were further investigated for the possible changes in the structure of sponge-like adsorbent after coating the GO sheets on the 3D porous structure of PS. The results showed that the CS had possessed effectively organic dye removal performances comparing to the PS. In the adsorption, the Langmuir and pseudo-second-order models corresponding to a monolayer approach and a chemical adsorption were appropriated. The maximum adsorption capacity of Rhodamine B and Congo red reached 126.8 and 135.0 mg·g-1; and 145.6 and 148.6 mg·g-1corresponding onto the PS and CS. It indicates that the maximum adsorption capacity on the CS enhanced significantly comparing to those on the PS owing to the functional GO sheets coated in the 3D porous structure of PS, which leads to supplying further functional adsorption sides on the whole 3D porous structure of CS. Notably, the sponges-like adsorbents could be regenerated and used again without a remarkable decrease of dye removal ability occurred in 9 adsorbing–desorbing cycles. Therefore, the CS prepared in this study can become a potential adsorbent for actual applications because of non-toxic materials, proper structural features, low-cost material and operation, and reliable recyclability.

关键词： Graphene oxide Biopolymer sponge Organic dye Adsorption Dye removal Recyclability

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Graphene oxide-covered melamine foam utilizing as a hybrid foam toward organic dye removal and recyclability

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Progress in Natural Science:Materials International 2022年第3期32卷 296-303页

作者： thi Sinh Vo tran thi Bich Chau Vo School of Mechanical Engineering Sungkyunkwan University Department of Industrial Management Can Tho University

Graphene-based adsorbents have been attracted extensive interest in recent years. Herein, graphene oxidecovered melamine foam(GO-covered MF) was designed and prepared by a mild submerge-covering method with the support of a super-hydrophilic melamine framework, showing its adsorption performances for various organic dyes. The structure morphology as well as chemical, thermal and mechanical properties of the as-obtained hybrid foam(HF) were further determined for the possible structure changes after covering the GO sheets on the MF framework. Moreover, the HF exhibited an excellent ability for organic dye adsorption application, and which was well fitted in the pseudo-second-order kinetic and Langmuir models corresponding to a chemical adsorption and a mono-layer approach during the adsorption process. The maximum adsorption capacity by using the asobtained HF corresponded to 258.56 mg g-1(methylene blue), 233.22 mg g-1(Rhodamine B), 206.92 mg g-1(methyl orange), and 184.93 mg g-1(Congo red), which are competitive with that of other graphene-based absorbents. In particular, the HF could be reused without a noticeable degradation of organic dye removal performance. As such, the HF prepared in this study can become an encouraging candidate for practical application owing to the reliable recyclability and low-cost.

关键词： Graphene oxide Melamine foam Organic dye Adsorption Hybrid foam Recyclability

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Surface characterization of polyimide and polyethylene terephthalate membranes toward plasma and UV treatments

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Progress in Natural Science:Materials International 2022年第3期32卷 314-327页

作者： thi Sinh Vo tran thi Bich Chau Vo School of Mechanical Engineering Sungkyunkwan University Department of Industrial Management Can Tho University

this study is to bring an overview on various methods regarding the surface treatment performed on different polymeric membranes in relation to a deference between the treatment mechanism and their chemical ***, plasma and UV surface treatments(PST and UST) were utilized to treat the surfaces of two commercial membranes, i.e., aromatic polyimide and polyethylene terephthalate for various durations using a discharge electrode and an UV LED curing system, respectively. Based on the effects of PST and UST processes on the surface of these membranes, their surface properties have been characterized to surface morphology and hydrophilicity(or wettability), at same time the changes have probably occurred on their surface during the PST and UST processes. As a result, their hydrophilic behavior was significantly enhanced after conducting these treatment processes based on the investigation of water contact angle. Moreover, Fourier-transform infrared and Raman spectroscopy manifested the changes in the chemical bonds, interactions and orientations of molecules, which confirmed the apparition and insertion of polar functional groups after the surface treatments, and accordingly,their wettability was enhanced significantly. Also, optical microscopy images showed direct impactions on their surface and the evidence of slight surface aging/damage during the treatment processes based on the presentation of the strange streaks on the treated surfaces. In particular, the peel forces exhibited an increase comparing to the initial membranes, which is characteristically for enhancing their adhesion behavior. Hence, these results are needful for improving the surface properties of a material, and obtaining better adhesion behavior on the membrane-like materials and recycling polymer materials.

关键词： Plasma treatment UV treatment Polymeric membrane Aromatic polyimide Polyethylene terephthalate

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transient response of doubly-curved bio-inspired composite shells resting on viscoelastic foundation subject to blast load using improved first-order shear theory and isogeometric approach

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Defence Technology（防务技术） 2024年第8期38卷 171-193页

作者： Thuy tran thi Thu Tu Nguyen Anh Hue Nguyen thi Hong Nguyen thi School of Mechanical and Automotive Engineering Hanoi University of IndustryHanoiViet Nam Faculty of Technical Fundamental University of Transport TechnologyHanoiViet Nam Faculty of Mechanical Engineering Thuyloi University175 Tay SonDong DaHanoiViet Nam

Investigating natural-inspired applications is a perennially appealing subject for scientists. The current increase in the speed of natural-origin structure growth may be linked to their superior mechanical properties and environmental resilience. Biological composite structures with helicoidal schemes and designs have remarkable capacities to absorb impact energy and withstand damage. However, there is a dearth of extensive study on the influence of fiber redirection and reorientation inside the matrix of a helicoid structure on its mechanical performance and reactivity. The present study aimed to explore the static and transient responses of a bio-inspired helicoid laminated composite(B-iHLC) shell under the influence of an explosive load using an isomorphic method. The structural integrity of the shell is maintained by a viscoelastic basis known as the Pasternak foundation, which encompasses two coefficients of stiffness and one coefficient of damping. The equilibrium equations governing shell dynamics are obtained by using Hamilton's principle and including the modified first-order shear theory,therefore obviating the need to employ a shear correction factor. The paper's model and approach are validated by doing numerical comparisons with respected publications. The findings of this study may be used in the construction of military and civilian infrastructure in situations when the structure is subjected to severe stresses that might potentially result in catastrophic collapse. The findings of this paper serve as the foundation for several other issues, including geometric optimization and the dynamic response of similar mechanical structures.

关键词： Blast load Modified first-order shear theory Biological composite structures

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Instability of colloidal lead halide perovskite nanocrystals:Causes,improvement,and evaluation

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Nano Research 2024年第12期17卷 10607-10619页

作者： thi Kim tran tran Hawi N.Nyiera Jing Zhao North Eagleville Road Department of ChemistryUniversity of ConnecticutStorrsConnecticut 06269USA

The instability of colloidal lead halide perovskite nanocrystals(NCs)presents a significant challenge for their application in optoelectronic *** review examines the primary causes of instability in these NCs and the proposed mechanisms of *** also introduces the recently developed synthesis and surface passivation methods to address the instability issue of colloidal perovskite ***,we focus on the various types of ligands and precursors introduced during NC synthesis or post-treatment and how they impact the structural and optical properties of the perovskite *** review also proposes a systematic approach to evaluating stability enhancement strategies by establishing key parameters and ranking them based on working and processing ***,we discuss the issues that need to be addressed in future research to achieve practical application of lead halide perovskite NCs in advanced optoelectronic systems.

关键词： lead halide perovskites colloidal nanocrystals stability optical properties

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Highly active brookite TiO2-assisted photocatalytic degradation of dyes under the simulated solar-UVA radiation

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Progress in Natural Science:Materials International 2019年第6期29卷 641-647页

作者： Huyen tran thi Thuong Chi tran thi Kim Liem Nguyen Quang Hendrik Kosslick Institute of Materials Science (IMS) Vietnam Academy of Science and Technology (VAST) University of Rostock Institute of Chemistry Department of Inorganic Chemistry

Brookite TiO2nanoparticles were synthesized by hydrothermal method and characterized by X-ray powder diffraction(XRD), diffuse reflectance UV–Visible spectroscopy(DRUV), and scanning electron microscopy(SEM). The obtained particles were spherical in shape with the diameter of about ～10 nm under the hydrothermal temperature of 175 °C. The photocatalytic performance of brookite was investigated in the photodegradation of dyes(rhodamine B and rose bengal) under UV-A radiation by low-power lamp. The activity of brookite and the photodegradation efficiency of dyes were estimated using a UV–Visible spectrophotometer and a total organic carbon(TOC) analyzer. Compared to anatase and rutile prepared by the similar synthesis procedure, brookite is highly active in terms of decolourization, aromatic ring opening, and mineralization.

关键词： Brookite Anatase Dye Photocatalytic degradation Decolourization Mineralization

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