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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

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Isogeometric analysis for free vibration of bidirectional functionally graded plates in the fluid medium

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Defence Technology（防务技术） 2022年第8期18卷 1311-1329页

作者： Quoc-Hoa Pham Phu-Cuong Nguyen Van Ke tran Trung Nguyen-Thoi Faculty of Civil Engineering Ho Chi Minh City Open UniversityHo Chi Minh CityViet Nam Faculty of Mechanical Engineering Le Quy Don Technical UniversityHanoiViet Nam Division of Computational Mathematics and Engineering Institute for Computational ScienceTon Duc Thang UniversityHo Chi Minh CityViet Nam Faculty of Civil Engineering Ton Duc Thang UniversityHo Chi Minh CityViet Nam

This paper for first time proposes an isogeometric analysis (IGA) for free vibration response of bi-directional functionally graded (BDFG) rectangular plates in the fluid medium. Material properties of the BDFG plate change in both the thickness and length directions via power-law distributions and Mori-Tanaka model. The governing equation of motion of BDFG plate in the fluid-plate system is formulated basing on Hamilton's principle and the refined quasi three-dimensional (3D) plate theory with improved function f(z). The fluid velocity potential is derived from the boundary conditions of the fluid-plate system and is used to determine the added mass. The discrete system of equations is derived from the Galerkin weak form and numerically analyzed by IGA. The accuracy and reliability of the proposed solutions are verified by comparing the obtained results with those published in the literature. Moreover, the effects of the various parameters such as the interaction boundary condition, geometric parameter, submerged depth of plate, fluid density, fluid level, and the material volume control coefficients on the free vibration behavior of BDFG plate in the fluid medium are investigated in detail. Some major findings regarding the numerical results are withdrawn in conclusions.

关键词： Contact plate-fluid Refined quasi 3D plate theory Mori-Tanaka model Isogeometric analysis Bidirectional functionally graded plate

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Prediction of acute stroke progression by the National Institutes of Health Stroke Scale

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Journal of Geriatric Cardiology 2007年第4期4卷 225-228页

作者： Vinh Phuong tran Van Huy Department of Geriatric Cardiology Khanh Hoa HospitalVietnam

Objective To determine the occurrence of neurological changes during the first 48 hours after acute stroke as it relates to the initial stroke severity assessment. Methods The assessment with the National Institutes of Health Stroke Scale (NIHSS) was performed serially for the first 48 hours on 68 consecutive ischemic stroke patients admitted to the Department of Geriatric Cardiology at the Khanh Hoa Hospital, Nha trang, Vietnam. Incidence of stroke progression (a ≥ 3-point increase on the NIHSS) was recorded and analysis performed to determine its association with initial stroke severity and other demographic and physiological variables. Deficit resolution by 48 hours, defined as an NIHSS score of 0 or 1, measured the frequency of functional recovery predicted by the initial deficit. Results Overall progression was noted in 28% of events (19/68). Applying Bayes' solution to the observed frequency of worsening, the greatest likelihood of predicting future patient progression occurred with NIHSS score of =7 and >7. Patients with an initial NIHSS score of =7 experienced a 13% (6/47) worsening rate versus those of an initial score of >7 with a 62% (13/21) worsening rate (P7 returned to a normal examination within this period (χ2, P<0.05). Conclusions This study suggests that the early clinical course of neurological deficit after acute stroke be dependent on the initial stroke severity and that a dichotomy in early outcome exist surrounding an initial NIHSS score of 7. These findings may have significant implications for the design and patient stratification in treatment protocols with respect to primary clinical outcome.(J Geriatr Cardiol 2007;4:225-228.)

关键词： stroke prediction

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Evaluation of the Ability to Apply Near-Infrared Spectroscopy on Direct Assay of Acyclovir in Tablets

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Journal of Pharmacy and Pharmacology 2017年第12期5卷 841-849页

作者： Le Dinh Chi tran Viet hung Bui Van Trung Doan Cao Son . The Department of Analytical Chemistry and Toxicology Hanoi University of Pharmacy Hanoi 110403 Vietnam Director Institute of Drug Quality Control Ho Chi Minh City Ho Chi Minh City 712161 Vietnam The Laboratory of Physical Measurements National Institute of Drug Quality Control Hanoi 110116 Vietnam Director National Institute of Drug Quality Control Hanoi 110116 Vietnam

This paper aimed at developing a simple and fast approach using chemometrics processing for direct assay of acyclovir in tablets by NIR （near infrared） spectroscopy in diffuse reflectance mode. In making trials with 5 different tablet matrices, the experimental results showed that regardless the matrix variation, it was always possible to construct a quantitative model with suitable linear range, accuracy and precision for direct assay of acyclovir in tablet from NIR spectra. Therefore, the approach used in this study was suitable for on-site fast assay of APIs in tablets during manufacturing process or in post-marketing surveillance of drug quality.

关键词： Near-infrared spectroscopy chemometrics acyclovir tablet partial least square regression direct assay.

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Some problems on the research and development of the application of methane draining boring technology to prevent hazards in underground coal mines in Vietnam

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Journal of Coal Science & Engineering(China) 2009年第2期15卷 129-133页

作者： NGUYEN Xuan-Thao NGUYEN tran-Tuan tran Dinh-Kien Institute of Mining Science and Technology University of Mining and Geology

Underground coal mining activities in the Quangninh coal basin (in the North ofVietnam) have been carried out at a depth of-130 m to-150 m,and in the near future thismining depth will become-300 m and-500 *** with the increasing coal output,the quantity of methane and other mine gases emitted from coal beds during mining activitieswill grow bigger and *** to the forecast of the coal mining industry,ifmines go deeper downward,all underground coal mines in the Quangninh basin will beclassified into the mine group with the dangerous level of methane *** gascontrol and management operations with conventional ventilation are less effective andentail high *** of the main solutions is to carry out short,medium and longboreholes for controlling and recovering methane and other mine gases from coal bedsbefore mining *** of drilling activities for methane gas recovery from coalseams with horizontal bore holes at underground coal mines depends on many factors includingthe mine gas draining borehole layout at the roadways,gas content in the coalbeds,technologies for mine gas draining boring activities,and so *** gas existsin the coal beds under the adhesive state with stable physical and chemical *** orderto recover these gases,it is necessary to carry out boreholes and create artificial joints(collecting pits) in coal beds with the impulse method (hydraulic separation method).

关键词： problems methane draining bodng technology Vietnam

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One-loop formulas for H→Zνlνl for l=e, μ, τ in 't Hooft-Veltman gauge

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Chinese Physics C 2023年第5期47卷 118-137页

作者： Dzung Tri tran Khiem Hong Phan Institute of Fundamental and Applied Sciences Duy Tan University Faculty of Natural Sciences Duy Tan University

In this paper,we present analytical results for one-loop contributions to the decay processes H→■(for l=e,μ,τ).The calculations are performed within the Standard Model framework in the ’t Hooft-Veltman ***-loop form factors are then written in terms of scalar one-loop functions in the standard notations of *** a result,one-loop decay rates for the decay channels can be evaluated numerically by using the ***,we analyze the signals of H→■l via the production processes e-e+→ZH*→Z(H*→■),including the initial beam polarizations at future lepton *** Standard Model backgrounds,such as the processes e-e+→■,are also examined in this *** results indicate that one-loop corrections make contributions of approximately 10% to the decay *** are sizeable contributions and should be taken into account at future *** show that the signals H→■l are clearly visible at the center-of-mass energy ■ =GeV and are difficult to probe in higher-energy regions owing to the dominant backgrounds.

关键词： analytic methods for quantum field theory dimensional regularization future colliders Higgs phenomenology one-loop Feynman integrals

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A High-order Coupled Compact Integrated RBF Approximation Based Domain Decomposition Algorithm for Second-order Differential Problems

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Computer Modeling in Engineering & Sciences 2015年第4期104卷 251-304页

作者： C.M.T.Tien N.Pham-Sy N.Mai-Duy C.-D.tran T.tran-Cong Computational Engineering and Science Research Centre Faculty of HealthEngineering and SciencesThe University of Southern QueenslandToowoombaQueensland 4350Australia

This paper presents a high-order coupled compact integrated RBF(CC IRBF)approximation based domain decomposition(DD)algorithm for the discretisation of second-order differential *** Schwarz DD algorithms,including one-level additive/multiplicative and two-level additive/multiplicative/hybrid,are *** CCIRBF based DD algorithms are analysed with different mesh sizes,numbers of subdomains and overlap sizes for Poisson *** convergence analysis shows that the CCIRBF two-level multiplicative version is the most effective algorithm among various schemes employed ***,the present CCIRBF two-level method converges quite rapidly even when the domain is divided into many subdomains,which shows great promise for either serial or parallel *** practical tests,we then incorporate the CCIRBF into serial and parallel two-level multiplicative *** numerical examples,including those governed by Poisson and Navier-Stokes equations are analysed to demonstrate the accuracy and efficiency of the serial and parallel algorithms implemented with the *** results show:(i)the CCIRBF-Serial and-Parallel algorithms have the capability to reach almost the same solution accuracy level of the CCIRBF-Single domain,which is ideal in terms of computational calculations;(ii)the CCIRBF-Serial and-Parallel algorithms are highly accurate in comparison with standard finite difference,compact finite difference and some other schemes;(iii)the proposed CCIRBF-Serial and-Parallel algorithms may be used as alternatives to solve large-size problems which the CCIRBF-Single domain may not be able to deal *** ability of producing stable and highly accurate results of the proposed serial and parallel schemes is believed to be the contribution of the coarse mesh of the two-level domain decomposition and the CCIRBF *** is noted that the focus of this paper is on the derivation of highly accurate serial and parallel algorithms

关键词： Coupled compact integrated RBF (CCIRBF) Schwarz domain decomposition one-level two-level coarse meshes additive multiplicative hybrid serial parallel colouring technique Poisson equation Naiver-Stokes equation liddriven cavity

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Effects of C/N ratio on nitrate removal and floc morphology of autohydrogenotrophic bacteria in a nitrate-containing wastewater treatment process

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Journal of Environmental Sciences 2018年第7期30卷 52-60页

作者： tran Ngoc Phu Nguyen Shu-Ju Chao Pei-Chung Chen Chihpin Huang Institute of EnvironmentaZ Engineering National Chiao Tung University Hsinchu 300 Chinese Taipei

The effects of C/N ratio of a nitrate-containing wastewater on nitrate removal performed by autohydrogenotrophic bacteria as well as on the morphological parameters of floc such as floc morphology, floc number distribution, mean particle size（MPS）, aspect ratio and transparency were examined in this study. The results showed that the nitrate reduction rate increased with increasing C/N ratio from 0.5 to 10 and that the nitrogen removal of up to 95% was found at the C/N ratios of higher than 5（between 0.5–10）. Besides, high C/N ratio values reflected a corresponding high nitrite accumulation after 12-hr operation, and a fast decreasing rate of nitrite in the rest of operational time. The final p H values increased with the C/N ratio increasing from 0.5 to 2.5, but decreased with the C/N ratio increasing from2.5 to 10. There were no significant changes in floc morphology with the MPSs ranging from35 to 40 μm. Small and medium-sized flocs were dominant in the sludge suspension, and the number of flocs increased with the increasing C/N ratios. Furthermore, the highest apparent frequency of 10% was observed at aspect ratios of 0.5 and 0.6, while the transparency of flocs changed from 0.1 to 0.7.

关键词： Autohydrogenotrophic bacteria C/N ratio Floc morphology Nitrate reduction Nitrite accumulation Nitrogen removal

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The Continuous Knapsack Problem with Capacities

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Journal of the Operations Research Society of China 2021年第3期9卷 713-721页

作者： Huynh Duc Quoc Nguyen Chi Tam tran Hoai Ngoc Nhan Department of Mathematics College of Natural ScienceCan Tho UniversityCan Tho City 900900Vietnam Faculty of Basic Sciences Vinh Long University of Technology EducationVinh Long 940000Vietnam

We address a variant of the continuous knapsack problem,where capacities regarding costs of items are given into *** prove that the problem is NP-complete although the classical continuous knapsack problem is solvable in linear *** the case that there exists exactly one capacity for all items,we solve the corresponding problem in O(n log n)time,where n is the number of items.

关键词： Knapsack problem Complexity Capacity Polynomially solvabl

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Synthesis of cation exchange resin-supported iron and magnesium oxides/hydroxides composite for nitrate removal in water

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Chinese Journal of Chemical Engineering 2021年第4期34卷 378-384页

作者： Trung Thanh Nguyen Vu Anh Khoa tran Le Ba tran Phuoc Toan Phan Minh Tan Nguyen Long Giang Bach Surapol Padungthon Cong Khiem Ta Nhat Huy Nguyen Nanomaterial Laboratory An Giang University18 Ung Van Khiem St.Dong Xuyen DistLong Xuyen CityAn Giang ProvinceViet Nam Vietnam National University Ho Chi Minh City Linh Trung WardThu Duc DistrictHo Chi Minh CityViet Nam Faculty of Natural Resources and Environment Ho Chi Minh City University of Technology(HCMUT)268 Ly Thuong Kiet St.Dist.10Ho Chi Minh CityViet Nam Faculty of Engineering-Technology-Environment An Giang University18 Ung Van Khiem StDong Xuyen DistLong Xuyen CityAn Giang ProvinceViet Nam Department of Scientific Research and International Relation Bac Lieu University178 Vo Thi Sau St.Ward 8Bac Lieu CityBac Lieu ProvinceViet Nam NTT Institute of High Technology Nguyen Tat Thanh University298-300A Nguyen Tat ThanhHo Chi Minh CityViet Nam Department of Environmental Engineering Khon Kaen University123 Moo 16 Mittraphap Rd.Nai-MuangMuang DistrictKhon Kaen 40002Thailand

In this study,we reported on the concept and practical use of cation exchange resin(CER)for removing anions in water via pretreating the CER with metal *** cation exchange resinsupported iron and magnesium oxides/hydroxides composite(FeMg/CER)was synthesized and introduced as a new and potential adsorbent for selective removal of nitrate ion in the water *** of FeMg/CER were determined by techniques such as Fouriertransform infrared spectroscopy,scanning electron microscopy,and Xray *** results showed that FeMg/CER material had a high nitrate adsorption capacity of 200 mg NO_(3)^()·g^(1)with a fast equilibrium adsorption time of 30 min at pH *** addition,it had good durability of at least 10 times of regeneration,which could be applied to practical water and wastewater treatment.

关键词： Iron oxide/hydroxide Magnesium oxide/hydroxide Cation exchange resin Adsorption Environment Nanomaterials

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