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Assessment of soil quality indicators under different agricultural land uses and topographic aspects in Central Vietnam

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International Soil and Water Conservation Research 2018年第4期6卷 280-288页

作者： Tung Gia Pham hung Trong nguyen Martin Kappas Cartography GIS and Remote Sensing DepartmentGottingen UniversityGeorge August University of GoettingenGoldschmidstr.537077 GoettingenGermany University of Agriculture and Forestry Hue UniversityVietnam Ministry of Natural Resources and Environment Vietnam

Soil quality assessment is valuable for agricultural production. In this research, 155 soil samples at two soil depths were collected from four land use types in an agricultural area of the A Luoi district in the Central Vietnam. Differences of soil organic carbon, total nitrogen in soil and soil pH under different land use types and topographic aspects were compared. Soil organic carbon contents in arable land and plantation forest are higher than those in natural forest and grassland (p < 0.05). Conversely, the total nitrogen in natural forest was significantly lesser in comparison to other land use types. Meanwhile there were no significant differences of the total nitrogen content (p < 0.05) among arable land, plantation forest, and grassland. The soil of grassland, natural and plantation forests land use types were more significantly acidic than those of the soils of the arable land use type. Soil organic carbon and total nitrogen showed a decreasing trend while soil depth increased in all land use types. The soil pH in plantation forest and arable land use types showed no significant change in relation to soil depth. Significant differences were not found in topographic aspects and soil organic carbon content;however, the different changing trends of soil organic carbon content between land use types and aspects were found. The impact of slope, elevation, farming system or soil texture accounted for the differences in these soil indicators under different land use types in the A Luoi district.

关键词： Central Vietnam Land use type Hilly area Soil quality Topographic aspects

Zirconium metal organic framework for design of tetragonal rare earth-doped zirconia nanoparticles

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Journal of Rare Earths 2019年第11期37卷 1230-1236页

作者： Lam Thi Kieu Giang Lukasz Marciniak Krzysztof Kamil Zur dinh Manh Tien nguyen Vu nguyen Thanh Binh Tran Kim Anh Le Quoc Minh Institute of Materials Science Vietnam Academy of Science and Technology18 Hoang Quoc VietCau GiayHanoiViet Nam Graduate University of Science and Technology Vietnam Academy of Science and Technology18 Hoang Quoc VietCau GiayHanoiViet Nam Institute of Low Temperature and Structural Research Polish Academy of Sciencesul.Okolna 250-422 WroclawPoland Faculty of Mechanical Engineering Bialystok University of TechnologyWiejska 45C15-351 BialystokPoland Institute of Applied Physics and Scientific Instrument Vietnam Academy of Science and Technology18 Hoang Quoc VietCau GiayHanoiViet Nam Duy Tan University 03 Quang TrungDa NangViet Nam

Zirconium metal-organic frameworks ZrOBDC(where BDC=C6H4(COOH)2,terephthalic acid)doped and co-doped with rare earth ions Ln(ZrOBDC:Ln^3+,where Ln^3+=Eu3+and Tb^3+as well as Er^3+and Yb^3+)were used as precursors for the design of tetragonal rare earth doped zirconia nanoparticles(t-ZrO2:Ln^3+NPs)through annealing ***,characterization and luminescence properties of ZrOBDC:Ln^3+and ZrO2:Ln^3+NPs were *** as-obtained t-ZrO2:Ln^3+NPs have high purity with an average size of 20-30 *** luminescence spectra of ZrOBDC:Tb^3+and ZrOBDC:Eu3+display strong green and red emission at around 544 and 611 nm which correspond to 5D4→7F5 and 5D0→7F2 transitions of Tb^3+and Eu3+ions,*** green and red up-conversion emissions of ZrO2:Er^3+,Yb^3+NPs due to 2H11/2,4S3/2→4I15/2 and 4F9/2→4I15/2 transitions of the Er^3+ions are observed under 976 nm laser excitation.

关键词： Zirconium Rare earth ZrOBDC ZrOBDC:Ln3+ ZrO2:Ln3+ Up-conversion

Double-loop Control Structure Using Proportional Resonant and Sequence-decoupled Resonant Controllers in Static Coordinates for Dynamic Voltage Restorer

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Chinese Journal of Electrical Engineering 2019年第3期5卷 10-19页

作者： Vu Thai hung Hongchun Shu Le Ngoc Giang nguyen Duc The School of Electric Power Engineering Kunming University of Science and TechnologyKunming 650500China AD-AF Academy of Viet Nam Son TayHa Noi 100000Viet Nam

Among incidents on grids,the sag/swell voltage is considered as the most frequent *** solve this problem,custom power devices are *** particular,the dynamic voltage restorer(DVR)is a modern and efficient customer *** are used to mitigate voltage sag/swells and harmonics on the load bus,thus protecting the sensitive *** DVR is a serial compensator that applies a voltage to the point of common coupling to maintain the voltage of sensitive load at the nominal *** improve the performance of DVRs,in this study,the control strategy of the two-stage loop circuit is *** external voltage control loop uses a sequence-decoupled resonant(SDR)controller,and the inner current-control loop uses the proportional resonant(PR)controller implemented in the stationary frameαβ.

关键词： Dynamic voltage restorer PR controller SDR controller nonlinear load

Forecasting Damage Mechanics By Deep Learning

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Computers, Materials & Continua 2019年第9期61卷 951-977页

作者： Duyen Le Hien nguyen Dieu Thi Thanh Do Jaehong Lee Timon Rabczuk hung nguyen-Xuan CIRTech Institute Ho Chi Minh City University of Technology(HUTECH)Ho Chi Minh CityVietnam Department of Architectural Engineering Sejong University209 Neungdong-roGwangjin-guSeoulKorea Institute of Structural Mechanics Bauhaus-Universität Weimar99423WeimarGermany Department of Physical Therapy Graduate Institute of Rehabilitation ScienceChina Medical UniversityTaichung40402Taiwan

We in this paper exploit time series algorithm based deep learning in forecasting damage mechanics *** methodologies that are able to work accurately for less computational and resolving attempts are a significant demand *** on learning an amount of information from given data,the long short-term memory(LSTM)method and multi-layer neural networks(MNN)method are applied to predict *** examples are implemented for predicting fracture growth rates of L-shape concrete specimen under load ratio,single-edge-notched beam forced by 4-point shear and hydraulic fracturing in permeable porous media problems such as storage-toughness fracture regime and fracture-height growth in Marcellus *** predicted results by deep learning algorithms are well-agreed with experimental data.

关键词： Damage mechanics time series forecasting deep learning long short-term memory multi-layer neural networks hydraulic fracturing

Facile synthesis of FeFe2O4 magnetic nanomaterial for removing methylene blue from aqueous solution

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Progress in Natural Science:Materials International 2019年第6期29卷 648-654页

作者： Van-Phuc dinh Ngoc Quyen Tran nguyen-Que-Tran Le Quang-Huy Tran Trinh Duy nguyen Gr EEN), nguyen Tat Thanh University Van Tan Le Future Materials and Devices Laboratory Institute of Fundamental and Applied Sciences Duy Tan University Institute of Applied Materials Science VAST Graduate University of Science and Technology VAST Le Quy Don–LBT Highschool Bien Hoa City Dong Nai province Center of Excellence for Green Energy and Environmental Nanomaterials (CE Industrial University of Ho Chi Minh City

A facile and simple chemical precipitation method was utilized to synthesize FeFe2O4magnetic nanomaterial for removing methylene blue（MB） from aqueous solution. Characterizations of this material were examined by using XRD, SEM, FT-IR, TGA-DTG and BET methods. Factors affecting the uptake of methylene blue, including p H, adsorption time, and MB initial concentration were also studied. The measured data were fitted by using four isotherm models including Langmuir, Freundlich, Sips and Temkin. Results showed that the Sips model offers the best fit to the data. In addition, the monolayer MB adsorption capacity obtained from the Langmuir model was 42.35 mg g-1under the optimal conditions of p H = 10 and adsorption time = 80 min. In particular, the uptake of MB onto FeFe2O4magnetic nanomaterial obtained from the kinetic and mechanism studies of the adsorption was in good agreement with prediction of the pseudo-first-order model, whereas the electrostatic interaction was found to play a primary mechanism.

关键词： FeFe2O4 magnetic nanomaterial Adsorption Methylene blue Adsorption mechanism

Effect of Poly-Alkylene-Glycol Quenchant on the Distortion, Hardness, and Microstructure of 65Mn Steel

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Computers, Materials & Continua 2021年第6期67卷 3249-3264页

作者： Thi Xuan Tran Xuan Phuong nguyen Duong Nam nguyen dinh Toai Vu Minh Quang Chau Osamah Ibrahim Khalaf Anh Tuan Hoang Hanoi University of Science and Technology HanoiVietnam Ho Chi Minh City University of Transport Ho Chi Minh CityVietnam Vietnam Maritime University HaiphongVietnam Industrial University of Ho Chi Minh City(IUH) Ho Chi Minh CityVietnam Al-Nahrain Nanorenewable Energy Research Center Al-Nahrain UniversityBaghdadIraq Ho Chi Minh city University of Technology(HUTECH) Ho Chi Minh CityVietnam

Currently,the 65Mn steel is quenched mainly by oil *** though the lower cooling rate of oil compared to water reduces the hardness of steel post quenching,the deforming and cracking of parts are often *** the other hand,the oil media also has the disadvantage of being ammable,creating smoke that adversely affects the *** poly alkylene glycol(PAG)polymer quenchant is commonly used for quenching a variety of steels based on its advantages such as non-ammability and exible cooling rate subjected to varying concentration and stirring *** article examines the effect of PAG polymer quenching solution(with concentrations of 10%and 20%)on deformation,hardness,and microstructure of C-ring samples made of 65Mn ***,the performance of PAG polymer quenchant is also compared with those of two common quenching solutions:Water and *** cooling in water,the C-ring samples had the largest deformation and 2 times higher than the results obtained when a 10%PAG solution was *** particular,similar levels of deformation on the C-ring samples were observed in both cases of 20%PAG solution and oil as the primary quenching ***,the hardness level measured between the sampled parts quenched in the 20%PAG solution appeared to be more uniform than that obtained from the oil-quenched *** study of the microscopic structure of steel by optical microscopy combined with X-ray diffraction showed that the water hardened sample exhibited cracks and comprised of two phases,martensite and retained *** to the results of Electron Back Scattering Diffraction(EBSD)analysis and backscattering electronic image(BSE),the content of austenite residue in the sample when the sample was cooled in PAG 10 and 20%solution was 3.21%and 4.73%,respectively and smaller than the measurements obtained from oil quenching ***,the 65Mn steel is cooled in 20%PAG solution for high hardness and more evenly distributed than when it is q

关键词： Polyethylene glycol electron backscattering diffraction quenching media cooling rate backscattering electronic image

Morphological Change in the Northern Red River Delta,Vietnam

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Journal of Ocean University of China 2018年第6期17卷 1272-1280页

作者： BUI Vuong Van FAN Daidu nguyen Dac Ve TRAN dinh Lan TRAN Duc Thanh HOANG Van Long nguyen Thi Hong Hanh Institute of Marine Environment and Resources Vietnam Academy of Science and TechnologyHaiphong 18000Vietnam State Key Laboratory of Marine Geology Tongji UniversityShanghai 200092China Hanoi University of Mining and Geology Hanoi 10000Vietnam Graduate University of Science and Technology Vietnam Academy of Science and TechnologyHanoi 10000Vietnam

Coastal erosion has become a worldwide concern, typically in the densely populated Asian mega-river deltas. Severe coastal erosion in the southern Red River Delta(RRD) has been intensively studied. Coastal morphological change in the northern RRD was examined in detail through DEM(Digital Elevation Model) analysis based on time series of bathymetrical maps(1965–2004) and Landsat images(1975–2015) in this study. The results show that the northern RRD is featured by rapid coastal accretion in the past few decades, although suspended sediment flux has dropped by roughly 60% after the completeness of Hoa Binh Dam(HBD) in 1988 and relative sea level rose at 1.9 mm yr^(-1). However, accretion at the outer part of subtidal shoals and platforms was observed to slow down quickly or even turned into erosion in the last two decades. The resuspended sediments from the erosion zone can be transported landward to replenish the inner coastal zone, keeping the latter accretion in the near future to compensate for the sediment discharge decrease from the river. However, this lag effect should be terminated soon if other adverse effects go worse, e.g., damming rivers, sea-level rising, strengthening storms, land reclamation and other poor-designed coastal engineering. Coastal planners and managers should pay full attention to these changes.

关键词： Morphological change DEM coastal erosion coastal engineering coastal management tide-dominated Red River Delta

Sorption of biodegradation end products of nonylphenol polyethoxylates onto activated sludge

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Journal of Environmental Sciences 2004年第4期16卷 564-569页

作者： nguyen Viet hung Masafumi Tateda Michihiko Ike Masanori Fujita Shinji Tsunoi Minoru Tanaka Department of Environmental Engineering Department of Environmental Systems TechnologyDepartment of Environmental EngineeringDepartment of Environmental EngineeringResearch Center for Environmental PreservationResearch Center for Environmental Preservation Graduate School of Engineering Osaka University 2-1 Yamada-oka Suita Osaka 565-0871 Japan College of Technology Toyama Prefectural University 5180 Kurokawa Kosugi Imizu Toyama 939-0398 Japan Graduate School of Engineering Osaka University 2-1 Yamada-oka Suita Osaka 565-0871 Japan Graduate School of Engineering Osaka University 2-1 Yamada-oka Suita Osaka 565-0871 JapanOsaka University 2-4 Yamada-oka Suita Osaka 565-0871 JapanOsaka University 2-4 Yamada-oka Suita Osaka 565-0871 Japan

Nonylphenol(NP), nonylphenoxy acetic acid(NP1EC), nonylphenol monoethoxy acetic acid(NP2EC), nonylphenol monoethoxylate(NP1EO) and nonylphenol diethoxylate(NP2EO) are biodegradation end products(BEPs) of nonionic surfactant nonylphenolpolyethoxylates (NPnEO). In this research, sorption of these compounds onto model activated sludge was characterized. Sorption equilibrium experiments showed that NP, NP1EO and NP2EO reached equilibrium in about 12 h, while equilibrium of NP1EC and NP2EC were reached earlier, in about 4 h. In sorption isotherm experiments, obtained equilibrium data at 28℃ fitted well to Freundlich sorption model for all investigated compounds. For NP1EC, in addition to Freundlich, equilibrium data also fitted well to Langmuir model. Linear sorption model was also tried, and equilibrium data of all NP, NP1EO, NP2EO and NP2EC except NP1EC fitted well to this model. Calculated Freundlich coefficient(K F) and linear sorption coefficient(K D) showed that sorption capacity of the investigated compounds were in order NP>NP2EO>NP1EO>NP1EC≈NP2EC. For NP, NP1EO and NP2EO, high values of calculated K F and K D indicated an easy uptake of these compounds from aqueous phase onto activated sludge. Whereas, NP1EC and NP2EC with low values of K F and K D absorbed weakly to activated sludge and tended to preferably remain in aqueous phase.

关键词： activated sludge biodegradation end products endocrine disruptor nonylphenol polyethoxylates sorption

Leaf fossils of Sabalites(Arecaceae)from the Oligocene of northern Vietnam and their paleoclimatic implications

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Plant Diversity 2022年第4期44卷 406-416页

作者： Ai Song Jia Liu Shui-Qing Liang Truong Van Do hung Ba nguyen Wei-Yu-Dong Deng Lin-Bo Jia Cedric Del Rio Gaurav Srivastava Zhuo Feng Zhe-Kun Zhou Jian Huang Tao Su Institute of Palaeontology Yunnan Key Laboratory for PalaeobiologyMEC International Joint Laboratory for Palaeobiology and PalaeoenvironmentYunnan Key Laboratory of Earth System ScienceYunnan UniversityKunming650500China CAS Key Laboratory of Tropical Forest Ecology Xishuangbanna Tropical Botanical GardenChinese Academy of SciencesMengla666303China Vietnam National Museum of Nature Vietnam Academy of Science and Technology18 Hoang Quoc VietHanoiViet Nam Graduate Academy of Science and Technology Vietnam Academy of Science and Technology18 Hoang Quoc VietHanoiViet Nam CAS Key Laboratory of Plant Diversity and Biogeography of East Asia Kunming Institute of BotanyChinese Academy of SciencesKunming650204China Birbal Sahni Institute of Palaeosciences Lucknow226007India

Recent paleobotanical investigations in Vietnam provide a good opportunity to improve our understanding of the biodiversity and paleoclimatic conditions in the geological past of Southeast ***(Arecaceae)are a diverse family of typical thermophilous plants with a relatively low tolerance for *** this study,we describe well-preserved fossil palm leaves from the Oligocene Dong Ho Formation of Hoanh Bo Basin,northern *** of the fossil leaves,such as a fan-shaped costapalmate lamina,an unarmed petiole,a costa slightly enlarged at the base that then tapers distally into the blade,and well-preserved amphistomatic leaves with cuticles,suggest that they represent a new fossil species,which we herein designate Sabalites colaniae ***,***,*** et *** *** with other paleontological and palaeoclimatic evidence,we conclude that a warm climate prevailed in northern Vietnam and nearby areas during the Oligocene.

关键词： Fossil Leaf Oligocene Paleoclimate Palm Vietnam