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A Numerical Analysis of Turbulent Compressible Radial Channel Flow with Particular Reference to Pneumatic Controllers

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Journal of Thermal Science 2004年第1期13卷 24-29页

作者： Gilles Roy dinh Vo-ngoc Vadim Bravine Faculty of Engineering Université de MonctonMonctonNBCanadaE1A 3E9Faculty of EngineeringUniversité de MonctonMonctonNBCanadaE1A 3E9Faculty of EngineeringUniversité de MonctonMonctonNBCanadaE1A 3E9

A numerical analysis of turbulent axisymmetric radial compressible channel flow between a nozzle and a flat plate is presented in this paper. In particular, the application of this type of flow situation in pneumatic dimensional control systems is considered. The Spalart-Allmaras one-equation turbulence model is used. The resulting highly coupled PDE system has been solved using the control volume based numerical approach where the power-law scheme was used extensively to compute the diffusive and convective fluxes of momentum. Results show that local Mach numbers can easily achieve and surpass unity for typical industrial configurations. Also, in the case of a standard industrial nozzle geometry, the presence of a toroidal recirculation zone that moves radially outward is clearly identified in most cases. Separated flow areas are of particular concern as it has been shown previously that they can cause nozzle fouling in industrial applications. It has been shown that the size of this region is dependant on feed pressure. Considerable differences between results obtained using the Spalart-Allmaras and standard k- εturbulence models have also been noticed.

关键词： compressible radial flow numerical simulation pneumatic controllers impinging jet with confinement.

Determination of Helmert transformation parameters for continuous GNSS networks:a case study of the Géoazur GNSS network

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Geo-Spatial Information Science 2023年第1期26卷 125-138页

作者： dinh Trong Tran Jean-Mathieu Nocquet ngoc Dung Luong dinh Huy Nguyen Department of Geodesy and Geomatics Engineering Hanoi University of Civil EngineeringHanoiVietnam UniversitéCôte d’Azur CNRSObservatoire de la Côte d’AzurIRDValbonneFrance

In this paper,we propose an approach to determine seven parameters of the Helmert transfor-mation by transforming the coordinates of a continuous GNSS network from the World Geodetic System 1984(WGS84)to the International Terrestrial Reference *** includes(1)convert-ing the coordinates of common points from the global coordinate system to the local coordinate system,(2)identifying and eliminating outliers by the Dikin estimator,and(3)estimating seven parameters of the Helmert transformation by least squares(LS)estimation with the“clean”data(*** removed).Herein,the local coordinate system provides a platform to separate points’horizontal and vertical ***,the Dikin estimator identifies and eliminates outliers in the horizontal or vertical component *** is significant because common points in a continuous GNSS network may contain *** proposed approach is tested with the Géoazur GNSS network with the results showing that the Dikin estimator detects outliers at 6 out of 18 common points,among which three points are found with outliers in the vertical compo-nent ***,instead of eliminating all coordinate components of these six common points,we only eliminate all coordinate components of three common points and only the vertical component of another three common ***,the classical LS estimation is applied to“clean”data to estimate seven parameters of the Helmert transformation with a significant accuracy *** Dikin estimator’s results are compared to those of other robust estimators of Huber and Theil-Sen,which shows that the Dikin estimator performs ***,the weighted total least-squares estimation is implemented to assess the accuracy of the LS estimation with the same *** inter-comparison of the seven estimated parameters and their standard deviations shows a small difference at a few per million levels(E-6).

关键词： Continuous GNSS tectonic geodesy Dikin estimation Helmert transformation

Novel Criteria for Exponential Stability of Linear Non-Autonomous Functional Differential Equations

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Journal of Systems Science & Complexity 2019年第2期32卷 479-495页

作者： PHAM HUU ANH ngoc THAI BAO Tran CAO THANH Tinh NGUYEN dinh Huy Department of Mathematics Vietnam National University-HCMC International University Faculty of Information Systems Vietnam National University-HCMC University of Information Technology Department of Mathematics Vietnam National University-HCMC University of Information Technology Division of Applied Mathematics Faculty of Applied Sciences Vietnam National University-HCMC Ho Chi Minh city University of Technology

General linear non-autonomous functional differential equations are considered. Explicit criteria for exponential stability are given. Furthermore, the authors present an explicit robust stability bound for systems su... 详细信息

关键词： Exponential stability linear functional differential equations perturbation

Fabrication and Characterization of Multi-layer Heat Mirror with Photocatalytic Properties

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Chinese Physics Letters 2009年第11期26卷 152-155页

作者： Tran Le Tuan Tran Huu Chi Nguyen Dac ngoc Son Luu Minh Nam Hoang dinh Quan Nguyen Department of Applied Physics College of Natural Science National University of He Chi Mirth City 227 Nguyen Van Cu District 5 Ward 4 He Chi Minh City Vietnam Department of Chemical Engineering College of Technology National University of He Chi Minh City 168 Ly Thuong Kiet District 10 Ho chi Minh City Vietnam

A novel TiO2（5）/TiO2（buffer）/Ti（4）/Ag（3）/Ti（2）/TiO2（1） multi-layer film coating with corning glass is designed and fabricated by a dc magnetron sputtering method as a renovation of the well-known TiO2/Ti/Ag/Ti/TiO2 system in order to obtain a heat mirror system with photocatalytic properties due to sufficient thickness of the Ti02 layer. The outer TiO2 layer is fabricated in two steps, possibly claimed as two layers TiO2（5） and TiO2（buuer）, among which TiO2（buffer） the 70-nm-thick layer deposited in poor oxygen effectively minimizes the oxidation toward its neighbor Ti（4） layer. The optimal total thickness of the TiO2（5） and TiO（buffer） di-layer is found to be 300nm to yield a highly photo-catalytic property of the film without affecting the optical properties considerably. This multi-layer film can transmit light of above 75-85% in the visible spectrum （380 ≤ λ≤ 760 nm） and reflect radiation of above 90% in the infrared spectrum （ λ≥760 nm）. Such multi-layer coatings are strongly recommended not only as promising transparent heat mirrors but also as photo-catalytic films for architectural window coatings.

关键词： Condensed matter: electrical magnetic and optical Surfaces interfaces and thin films Chemical physics and physical chemistry

Sediment transport trends and cross-sectional stability of a lagoonal tidal inlet on the Central Coast of Vietnam

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International Journal of Sediment Research 2019年第4期34卷 322-334页

作者： Do Minh Duc Tran Thanh Tung Patrick Mc Laren Tran ngoc Anh dinh Thi Quynh Faculty of Geology VNU University of Science Vietnam National University Faculty of Marine and Coastal Engineering Thuyloi University Sed Trend Analysis Limited 4. Faculty of Meteorology Hydrology and Oceanography VNU University of Science Vietnam National University

Lagoonal tidal inlets are a typical morphology of the Central Coast of Vietnam. Recently, navigation channels in these inlets have become increasingly threatened by siltation. This study analyses the relations between sediment distribution and transport trends(using the technique of Sediment Trend Analysis-STAs) in the lagoonal system of the De Gi inlet and then proposes appropriate countermeasures against sand deposition in the navigation channel. The STA identified three types of transport trends in the De Gi inlet, namely dynamic equilibrium, net accretion, and net erosion. Processes associated with the tidal prism have resulted in trends of sediment transport and deposition across the flood and ebb tidal shoals, which maintain a present cross-sectional area of about 1000 m~2. However, longshore sediment transport from north to south resulting from northeast waves cause additional sand deposition in the channel. In addition, the effects of refraction associated with a nearby headland and jetty also increase sedimentation. These processes provide the main reasons for sediment deposition in the De Gi inlet. Short term and regular dredging helps to maintain the navigation channel. A system comprised of three jetties(north, south, and weir) is necessary to ensure the longterm cross-sectional stability of the navigation channel.

关键词： Lagoon Tidal inlet Sediment Trend Analysis (STA) Tidal prism Cross-sectional stability

任意角度水平向荷载下现浇X形桩力学特性研究(Ⅰ)：惯性矩

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岩土力学 2012年第9期33卷 2754-2758页

作者：周航孔纲强刘汉龙 thach Pham-ngoc 河海大学岩土力学与堤坝工程教育部重点实验室南京210098 河海大学土木与交通学院南京210098

现浇X形桩是为了提高单位混凝土承载力性能而开发的一种新型桩,异形横截面在确保桩周周长的前提下,能有效地减少混凝土用量;但目前针对异形横截面对水平向承载力特性影响方面的研究相对较少。基于X形横截面的3个控制参数:外包圆直径、... 详细信息

现浇X形桩是为了提高单位混凝土承载力性能而开发的一种新型桩,异形横截面在确保桩周周长的前提下,能有效地减少混凝土用量;但目前针对异形横截面对水平向承载力特性影响方面的研究相对较少。基于X形横截面的3个控制参数:外包圆直径、开弧间距和开弧弧度,建立任意方向轴惯性矩控制方程,并分析X形横截面3个控制参数对截面轴惯性矩的影响规律。最后,提出控制截面面积或周长情况下X形截面惯性矩的最优化设计方案。研究结果表明,X形截面惯性矩随着开弧角度、开弧间距的减小而增大,随着外包圆直径的增大而增大。因此,在等混凝土材料用量或者控制桩周长情况下,适当增大外包圆直径、减小开弧角度和开弧间距有利于提高X形截面轴惯性矩,从而提高X形桩整体水平向承载力。

关键词：软土地基水平向荷载截面几何性质现浇X形桩惯性矩

Effects of low energy (160 keV) X-ray on microbial inactivation,sprouting inhibition and genetic variation in potato

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Food Bioscience 2022年第3期47卷 262-270页

作者： Nguyen An Son Nguyen Thi Nguyet Ha Nguyen Thi Minh Sang Le Doan dinh Duc Le ngoc Trieu Faculty of Physic and Nuclear Engineering Da Lat UniversityViet Nam Dalat Vocational Training College Viet Nam Faculty of Biology Da Lat UniversityViet Nam

The effects of low energy X-ray irradiation on microbial inactivation,sprouting inhibition and genetic variation were *** was an inverse correlation between the exposure dose in range of 0 Gy–5000 Gy and the survival rate of *** dose of 1000 Gy seemed to be suitable for inactivation of microorganisms because the respective survival rate is relatively low (0.59%).Dose rate of 13.87 Gy/min was the most appropriate to inactivate the microorganisms,with the survival rate of 0.37%.Applying the irradiation dose of 1000 Gy and dose rate of 13.87 Gy/min,there was a significant sprouting inhibition of irradiated potatoes compared to the control for six months *** effect of irradiation dose (100–1200 Gy) and dose rate (8.63–19.62 Gy/min) on genetic variation of the irradiated samples was assessed by DNA fingerprints induced from using three molecular techniques including Random Amplified Polymorphic DNA (RAPD),Start Codon Targeted Polymorphism (SCoT) and CAAT box – derived polymorphism (CBDP).At the irradiation dose of 1000 Gy and dose rate of 13.87 Gy/min,the level of genetic variation was relatively low (4.85%).Thus,this treatment is a suitable condition of irradiation for potato treatment with the purpose of preservation.

关键词： Dose Dose rate Low energy X-ray Microbial inactivation Potato

Risk Management via Measuring Impacts of Micro and Macro Economic Factors on Financial Firm Stock Price—A Case of Mitsubishi UFJ in Japan

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Economics World 2020年第1期8卷 1-14页

作者： dinh Tran ngoc Huy Banking University HCM cityVietnam International University of Japan NiigataJapan

Mitsubishi UFJ(MUFJ)has made very positive contributions to the overall achievements of the banking industry,deserving its position as one of the leading financial groups in Japan,contributing to helping government stabilizes the market and successfully implement monetary *** is aiming for growth of approximately¥250 billion in net operating profits,with MUFG Group companies,business groups,and the corporate *** of stock price in financial groups such as MUFJ will reflect the business health of bank and financial system and the whole *** business management requires us to consider the impacts of multi micro and macro factors on stock price,and it contributes to promoting business plan and economic policies for economic growth and stabilizing macroeconomic *** data collection method through statistics,analysis,synthesis,comparison,quantitative analysis to generate qualitative comments and discussion;using econometric method to perform regression equation and evaluate quantitative results,the article analyzed and evaluated the impacts of six(6)micro and macro economic factors such as:cost,net sale,lending rate,inflation,GPD growth,S&P 500,*** stock price of a big financial group,MUFJ in Japan in the period of 2010-2019,both positive and negative *** results of quantitative research,in a seven-factor model,show that the decrease in inflation,GDP,and high lending rate has a significant effect on reducing MUFJ stock price with the highest impact coefficient,the second is increase in *** research finding and recommended policy also can be used as reference in policy for commercial bank and financial system in many developing countries.

关键词： MUFJ stock price GDP growth inflationary risk free rate market interest rate

Behavior of noncircular tunnels excavated in stratified rock masses-Case of underground coal mines

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Journal of Rock Mechanics and Geotechnical Engineering 2019年第1期11卷 99-110页

作者： ngoc Anh Do Daniel Dias Van Diep dinh Tien Tung Tran Van Canh Dao Viet Doan Dao Phuc Nhan Nguyen Department of Underground and Mining Construction.Faculty of Civil Engineering Hanoi University of Mining and Ceology School of Automotive and Transportation Engineering Hefei University of Technology Laboratory 35R Crenoble Alpes University

The amount of tunnels excavated along stratified/sedimentary rock masses in Quangninh coal mine area,Vietnam, is gradually increasing. Rock mass in Quangninh is characterized by beddings between rock layers. The behavior of stratified rock masses surrounding the tunnels depends on both the intact rock and the beddings between rock layers. The main characteristics of stratified rock masses that need to be considered are their heterogeneity and anisotropy. Depending on the dip angle of rock layers, movements and failure zones developed surrounding the tunnels can be asymmetrical over the vertical axis of tunnel. This asymmetry causes adverse behaviors of the tunnel structures. The objective of this study is to highlight convergences and yielded zones developed in rock masses surrounding noncircular tunnels in Quangninh coal mine area using a finite element method. The presence of bedding joints is explicitly simulated. The numerical results indicated that with the increase in dip angle of bedding joints, the stress asymmetry over the tunnel vertical axis increases. It gradually leads to an asymmetry of the failure zone surrounding the tunnel. An increase of rock mass quality means a decrease of rock mass sensitivity to the discontinuities. In addition,a dip angle of the bedding joints of approximately 45° could be considered as the critical angle at which the rock mass mechanism changes between sliding and bending.

关键词： Tunnel Bedding Stratification Anisotropic Heterogeneity