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Journal of Central South University 2014年第1期21卷 27-34页

作者： Duc-Toan nguyen duy-Khoe Dinh Hong-Minh Thi nguyen Tien-Long Banh Young-Suk Kim School of Mechanical Engineering Hanoi University of Science and Technology1A-Dai Co Viet StreetHai Ba Trung DistrictHanoi CityVietnam Department of Mechanical Engineering Hungyen University of Technology and EducationHungyenVietnam Department of Mechanical Engineering Kyungpook National University1370 SangyeokBuk-kuDaegu 702-701Korea

In the current work, to predict and improve the formability of deep drawing process for steel plate cold rolled commercial grade （SPCC） sheets, three parameters including the blanking force, the die and punch comer radius were considered. The experimental plan according to Taguchi＇s orthogonal array was coupled with the finite element method （FEM） simulations. Firstly, the data from the test of stress-strain and forming limit curves were used as input into ABAQUS/Explicit finite element code to predict the failure occurrence of deep drawing process. The three parameters were then validated to establish their effects on the press formability. The optimum case found via simulation was finally confirmed through an experiment. In order to obtain the complex curve profile of cup shape after deep drawing, the anisotropic behavior of earring phenomenon was modeled and implemented into FEM. After such phenomenon was correctly predicted, an error metric compared with design curve was then measured.

关键词： finite element method SPCC deep-drawing forming limit diagram criterion Taguchi's method earring prediction

Scouring of a granular bed by dam break: Experimental study and numerical simulation by a VOF-LPT coupling

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International Journal of Sediment Research 2023年第3期38卷 432-445页

作者： Quyen Thi le nguyen Viet Dung nguyen Patrice Coorevits EPROAD Research Unit University of Picardie Jules Verne IUT of Aisne Hanoi University of Civil Engineering

The first part of the research reported here consists of an experimental campaign to study the scouring of a granular bed(glass beads, sand) induced by a dam break in an open channel. Two configurations are considered: with and without cylinders. In the second part of this study, the volume of fluid method coupled with the shear stress transport turbulent model and the lagrangian particle tracking method is used to simulate the local scour processes. The four-way coupling is realized by considering the drag force and collisions between particles. Using a vortex map and velocity profiles, the flow dynamics and scour pattern can be studied. The current research also focuses on the profiles of the erodible particle bed and the sediment transport rate to study the effects of a cylinder on local scour. The presence of the cylinder increases the experimental erosion depth by up to 42%. It was found that for relatively close particle diameters(2 and 3 mm), a granular bed with larger porosity(larger diameter) erodes the *** and numerically it was found that the center of the granular bed experiences more erosion compared to the channel sides. In the last part of the research, comparisons between the numerical results and the experimental data allowed risk areas to be identified and the roles of porosity,sediment density, and flow dynamics on erosion to be identified.

关键词： Volume of fluid Lagrangian particle tracking Scour Granular bed Cylinder Dam break

A combination of damage locating vector method （DLV） and differential evolution algorithm （DE） for structural damage assessment

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Frontiers of Structural and Civil Engineering 2018年第1期12卷 92-108页

作者： T. nguyen-THOI A. TRAN-VIET N. nguyen-MINH T. VO-duy V. HO-HUU Division of Computational Mathematics and Engineering Institute for Computational Science Ton Duc Thang University Hochiminh City Vietnam Division of Construction Computation Institute for Computational Science Ton Duc Thang University Hochiminh City Vietnam Faculty of Civil Engineering Ton Duc Thang University Hochiminh City Vietnam

In this study, a two-stage method is presented for identifying multiple damage scenarios. In the first stage, the damage locating vector （DLV） method using normalized cumulative energy （nce） is employed for damage localization in structures. In the second stage, the differential evolution algorithm （DE） is used for damage severity of the structures. In addition, in the second stage, a modification of an available objective function is made for handing the issue of symmetric structures. To verify the effectiveness of the present technique, numerical examples of a 72-bar space truss and a one-span steel portal frame are considered. In addition, the effect of noise on the performance of the identification results is also investigated. The numerical results show that the proposed combination gives good assessment of damage location and extent for multiple structural damage cases.

关键词： damage assessment damage locating vector method (DLV) differential evolution (DE) multiple damagelocation assurance criterion (MDLAC) mode shape error function

Electronic Band Structure of Carbon Nanotubes with Kekule Structure

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Chinese Physics letters 2013年第9期30卷 97-100页

作者： nguyen Ngoc Hieu le Cong Nhan Center of Research and Development Duy Tan UniversityK7/25 Quang TrungDa NangViet Nam Department of Environmental Science Saigon University273 An Duong VuongHo Chi Minh cityViet Nam

Electronic band structure of carbon nanotubes with the Kekule structure is studied by the tight-binding *** give a complete geometrical approach to structural properties of carbon nanotubes with bond alternation,including chiral and achiral *** the Kekule is introduced,all carbon nanotubes become semiconducting with a small band gap at the Fermi *** band gap of the carbon nanotubes depends only on the difference between C–C bond lengths or the resonance integrals.

关键词： carbon structure Fermi

ON BOUNDEDNESS PROPERTY OF SINGULAR INTEGRAL OPERATORS ASSOCIATED TO A SCHRODINGER OPERATOR IN A GENERALIZED MORREY SPACE AND APPLICATIONS

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Acta Mathematica Scientia 2020年第5期40卷 1171-1184页

作者： Xuan Truong le Thanh Nhan nguyen Ngoc Trong nguyen Division of Computational Mathematics and Engineering Institute for Computational ScienceTon Due Thang UniversityHo Chi Minh CityVietnam Faculty of Mathematics and Statistics Ton Due Thang UniversityHo Chi Minh CityVietnam Department of Mathematics Ho Chi Minh City University of EducationHo Chi Minh CityVietnam Department of Primary Education Ho Chi Minh City University of EducationHo Chi Minh CityVietnam

In this paper,we provide the boundedness property of the Riesz transforms associated to the Schrodinger operator■=-Δ+V in a new weighted Morrey space which is the generalized version of many previous Morrey type *** additional potential V considered in this paper is a non-negative function satisfying the suitable reverse Holder's *** results are new and general in many cases of *** an application of the boundedness property of these singular integral operators,we obtain some regularity results of solutions to Schrodinger equations in the new Morrey space.

关键词： weighted Morrey spaces Schodinger operator riesz transforms Regularity estima tes

Production of asiaticoside from centella(Centella asiatica ***)cells in bioreactor

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Asian Pacific Journal of Tropical Biomedicine 2013年第10期3卷 806-810页

作者： nguyen Hoang Loc nguyen Thi duy Nhat Institute of Resources.Environment and Biotechnology.Hue University Hue 47000Vietnam

Objective:To investigate the effects of some culture conditions on production of asialicoside from centella(Centella asiatica ***)cells cultured in 5-L ***:The centell cell suspension culture was conducted in 5-L bioreactor to investigate the growth and asiaticoside accumulation under various *** content was determined by HPLC ***:The results showed that the cell growth and asiaticoside accumulation peaked after 24d of culture at an agitation speed of 150 r/min and aeration rate of 2.5 L/*** cell biomass reached a maximum value of 302.45 g fresh weight(31.43 g dry weight)and growth index of 3.03with inoculum size of 100 ***,asiaticoside content was the highest(60.08 mg/g dry weight)when culture was initiated with an inoculum size of 50 ***:The present study found the suitable conditions for growth of centella cells and their asiaticoside production in bioreactor.

关键词： Asiaticoside Bioreactor Centella asiatica Cell suspension culture

Effect of land use change on water discharge in Srepok watershed,Central Highland,Viet Nam

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International Soil and Water Conservation Research 2014年第3期2卷 74-86页

作者： nguyen Thi Ngoc Quyen nguyen duy Liem nguyen Kim Loi Tay nguyen University Viet Nam.567 Le Duan streetBuon Ma Thuot CityDak Lak Province Nong Lam University Viet Nam.Linh Trung WardThu Duc districtHo Chi Minh City

Srepok watershed plays an important role in Central Highland in Viet *** impacts to developing social-economic ***,it is necessary to research elements which impact to natural resources in this *** Soil and Water Assessment Tool(SWAT)model and Geography Information System(GIS)were used to simulate water discharge in the Srepok *** objectives of the research were to apply GIS and SWAT model for simulation water discharge and then,we assessed land use change which impacted on water discharge in the *** observed stream flow data from Ban Don Stream gauge station was used to calibrate for the period from 1981 to 2000 and then validate for the period from 2001 to *** using SWAT-CUP software to calibration,NSI reached 0.63 and R square value achieved 0.64 from 2004 to 2008 in calibration and NSI gained good level at 0.74 and R square got 0.75 from 2009 to 2012 in validation step at Ban Don *** that,land cover in 2010 was processed like land cover in 2000 and set up SWAT model *** simulated water discharge in scenario 1(land use 2000)was compared with scenario 2(land use 2010),the simulation result was not significant difference between two scenarios because the change of area of land use was not much enough to affect the fluctuation of water ***,the effect of land cover on water resource could be seen clearly via total water *** percentage of surface flow in 2000 was twice times more than in 2010;retard and base flow in 2000 was slightly more than in ***,decreased surface flow,increased infiltration capacity of water and enriched base flow resulted in the growth of land cover.

关键词： Water discharge Land use change GIS SWAT model Simulations

Assessing Satellite-Based Precipitation Products to Create Flood Forecasting in the Da River Basin, Vietnam

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Journal of Geoscience and Environment Protection 2019年第11期7卷 113-123页

作者： le Viet Son Luong Ngoc Chung Bui Tuan Hai Sai Hong Anh nguyen duy quang Division for Water Resources Planning for the North Region Institute of Water Resources Planning Hanoi Vietnam Board of directors Institute of Water Resources Planning Hanoi Vietnam Department of Agro-Environmental Sciences Graduate School of Bioresource and Bioenvironmental Sciences Kyushu University Fukuoka Japan

The Da River Basin is an international basin where available access to hydrological data is limited;it has a total basin area of 52,900 km2, about 50% of the area in which it is located, Vietnam. The Da River is the primary source of water for agriculture in 25 provinces and cities, and the primary source of drinking water for more than 30 million people in both urban and rural areas. It has huge economic and historical value. However, flood forecasting for the Da River basin has not been adequately addressed yet because of the challenge of the inconsistency, scarcity, poor spatial representation, as well as difficult access and incompleteness of the availability of ground observed rainfall data. In this research, the IFAS model has been utilized to assess the benefits of using satellite-based precipitation products to create flood forecasting for the whole research area. The results showed that the Integrated Flood Analysis System (IFAS) model was able to integrate the satellite-based precipitation products for simulating the flood event in the Da River basin. Also, the 3B42RT algorithm showed a definite improvement in reproducing the flood peak and low flow very well in the research area. These results could be used to enhance the effectiveness of flood management strategy in the basin.

关键词： IFAS Flood Flow 3B42RT and GSMaP Algorithm

Twin reversed arterial perfusion sequence-a rare and dangerous complication form of monochorionic twins:A case report

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World Journal of Clinical Cases 2022年第28期10卷 10214-10219页

作者： nguyen duy Anh nguyen-Thi Thu Ha nguyen-Thi Sim nguyen Khac Toan Phan-Thi huyen Thuong nguyen Minh Duc Fetal Medicine Center Hanoi Obstetrics and Gynecology HospitalHanoi 100000Vietnam Department of Assisted Reproduction Hanoi Obstetrics and Gynecology HospitalHanoi 100000Vietnam Department of Obstetrics and Gynecology Hanoi University of Medicine and PharmacyHanoi 100000Vietnam Department of Radiology Pham Ngoc Thach University of MedicineHo Chi Minh City 700000Vietnam

BACKGROUND Twin reversed arterial perfusion(TRAP) sequence is an extremely rare congenital anomaly in monochorionic(MC) *** condition is characterized by a malformed fetus(acardiac twin) without cardiac activities being perfused by a structurally normal one(pump twin) via an artery-to-artery anastomosis in a reverse *** SUMMARY We described the first case of TRAP to receive laser surgery in *** 26-wk pregnancy was originally misdiagnosed in another hospital as MC twins with single intrauterine fetal *** admission to our center,the diagnosis was amended to a 26-wk TRAP sequence stage *** acardiac twin was 7.5 cm at the longest length,the ratio of the weight of the acardiac twin to the weight of the pump twin was more than 90%,the pump twin showed fetal distress with absent diastolic flow in umbilical artery of pump twin,and the peak systolic velocity in the middle cerebral artery = 1.6 Mo *** performed emergency laser photocoagulation of the acardiac twin’s umbilical *** surgery,we successfully maintained the pregnancy for 8 wk and ended it electively by cesarean section at 34 wk of gestation due to rupture of *** TRAP should be appropriately diagnosed and treated early to avoid complications of the pump *** laser photocoagulation is a new and effective treatment for this condition.

关键词： Twin reversed arterial perfusion Acardiac twin Pump twin Laser Case report