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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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Predicted aerodynamic damping of slender single beam structures in across-wind vibrations

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Acta Mechanica Sinica 2020年第5期36卷 990-998,I0001页

作者： Cung huy nguyen dinh Tung nguyen Department of Civil Engineering Industrial University of Ho Chi Minh CityHo Chi Minh City 700000Vietnam Department of Civil Engineering University of NottinghamNottingham NG72RDUK

The paper presents a generalization of the conventional analytical approach where the quasisteady theory is utilised to evalu-ate the across-wind aerodynamic damping of slender single beam *** generalized theory considers the variation of structural and aerodynamic parameters along the structural height,together with the nature of the vertical wind profile and mode ***-form solutions for typical uniform and tapered tall buildings are given.A numerical application on a prototype tall building shows that the conventional method may be oversimplified,which results in incorrect predictions of the aerodynamic damping.

关键词： Aerodynamic damping Across-wind Slender structure-Galloping Tall building

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An analytical model for cross-Kerr nonlinearity in a four-level N-type atomic system with Doppler broadening

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Chinese Physics B 2022年第2期31卷 314-319页

作者： dinh Xuan Khoa nguyen huy Bang nguyen Le Thuy An nguyen Van Phu Le Van Doai Vinh University 182 Le Duan StreetVinh CityVietna

We present an analytical model for cross-Kerr nonlinear coefficient in a four-level N-type atomic medium under Doppler *** model is applied to87 Rb atoms to analyze the dependence of the cross-Kerr nonlinear coefficient on the external light field and the temperature of atomic *** analysis shows that in the absence of electromagnetically induced transparency(EIT)the cross-Kerr nonlinear coefficient is zero,but it is significantly enhanced when the EIT is *** means that the cross-Kerr effect can be turned on/off when the external light field is on or ***,the amplitude and the sign of the cross-Kerr nonlinear coefficient are easily changed according to the intensity and frequency of the external light *** amplitude of the cross-Kerr nonlinear coefficient remarkably decreases when the temperature of atomic medium *** analytical model can be convenient to fit experimental observations and applied to photonic devices.

关键词： electromagnetically induced transparency Kerr nonlinear effect Doppler effect

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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

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A deep feed-forward neural network for damage detection in functionally graded carbon nanotube-reinforced composite plates using modal kinetic energy

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Frontiers of Structural and Civil Engineering 2021年第6期15卷 1453-1479页

作者： huy Q.LE Tam T.TRUONG D.dinh-CONG T.nguyen-THOI Division of Computational Mathematics and Engineering Institute for Computational ScienceTon Duc Thang UniversityHo Chi Minh City 700000Vietnam Faculty of Civil Engineering Ho Chi Minh City University of TransportHo Chi Minh City 700000Vietnam Division of Construction Computation Institute for Computational ScienceTon Duc Thang UniversityHo Chi Minh City 700000Vietnam Faculty of Civil Engineering Ton Duc Thang UniversityHo Chi Minh City 700000Vietnam

This paper proposes a new Deep Feed-forward Neural Network(DFNN)approach for damage detection in functionally graded carbon nanotube-reinforced composite(FG-CNTRC)*** the proposed approach,the DFNN model is developed based on a data set containing 20000 samples of damage scenarios,obtained via finite element(FE)simulation,of the FG-CNTRC *** elemental modal kinetic energy(MKE)values,calculated from natural frequencies and translational nodal displacements of the structures,are utilized as input of the DFNN model while the damage locations and corresponding severities are considered as *** state-of-the art Exponential Linear Units(ELU)activation function and the Adamax algorithm are employed to train the DFNN ***,in order to enhance the performance of the DFNN model,the mini-batch and early-stopping techniques are applied to the training process.A trial-and-error procedure is implemented to determine suitable parameters of the network such as the number of hidden layers and the number of neurons in each *** accuracy and capability of the proposed DFNN model are illustrated through two distinct configurations of the CNT-fibers constituting the FG-CNTRC plates including uniform distribution(UD)and functionally graded-V distribution(FG-VD).Furthermore,the performance and stability of the DFNN model with the consideration of noise effects on the input data are also *** results indicate that the proposed DFNN model is able to give sufficiently accurate damage detection outcomes for the FG-CNTRC plates for both cases of noise-free and noise-influenced data.

关键词： damage detection deep feed-forward neural networks functionally graded carbon nanotube-reinforced composite plates modal kinetic energy

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Photocatalytic removal of NO and NO_2 using titania nanotubes synthesized by hydrothermal method

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Journal of Environmental Sciences 2014年第5期26卷 1180-1187页

作者： Nhat huy nguyen Hsunling Bai Institute of Environmental Engineering National Chiao Tung University

In this study, the photocatalysts of titania nanotubes （TNTs） were synthesized at different calcination temperatures using commercial Degussa TiO2 （P25） as a precursor. The materials were then characterized by BET, SEM, TEM, and XRD analyses. The photocatalytic reactions with NO and NO2 under UV-A irradiation were both performed. The results showed that the photocatalytic reaction rate of NO was much faster than that of NO2, and the conversion of NO2 to nitrate was the rate-limiting step for photocatalytic removal of NOx if the nitrate produced cannot be removed continuously from the photocatalyst surface. For TNTs calcined at different temperatures, a significant enhancement was observed on the total NOx removal efficiency by TNT calcined at 500℃ for both NO and NO2 photocatalytic reaction, which could be attributed to its high anatase crystallinity as well as high surface area. These two factors affect primarily on the NO2 conversion step in which the high anatase crystallinity could be responsible for the high efficiency at the beginning, while the high surface area could be accounted for retaining this high efficiency from nitric acid poisoning during the test period.

关键词： nitrogen oxides TNTs TiO2 indoor air pollution control environmental photocatalysis

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STABILITY ANALYSIS OF A COMPUTER VIRUS PROPAGATION MODEL WITH ANTIDOTE IN VULNERABLE SYSTEM

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Acta Mathematica Scientia 2016年第1期36卷 49-61页

作者： nguyen Huu KHANH nguyen Bich huy Department of Mathematics College of Natural SciencesCan Tho University Departmet of Mathematics Ho Chi Minh University of Education

We study a proposed model describing the propagation of computer virus in the network with antidote in vulnerable system. Mathematical analysis shows that dynamics of the spread of computer viruses is determined by the threshold Ro. If Ro 〈 1, the virusfree equilibrium is globally asymptotically stable, and if R0 〉 1, the endemic equilibrium is globally asymptotically stable. Lyapunov functional method as well as geometric approach are used for proving the global stability of equilibria. A numerical investigation is carried out to confirm the analytical results. Through parameter analysis, some effective strategies for eliminating viruses are suggested.

关键词： computer virus virus-free equilibrium endemic equilibrium global stability antidote

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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

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Push forward LC-MS-based therapeutic drug monitoring and pharmacometabolomics for anti-tuberculosis precision dosing and comprehensive clinical management

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Journal of Pharmaceutical Analysis 2024年第1期14卷 16-38页

作者： nguyen Quang Thu nguyen Tran Nam Tien nguyen Thi Hai Yen Thuc-huy Duong nguyen Phuoc Long huy Truong nguyen Department of Pharmacology and PharmacoGenomics Research Center Inje University College of MedicineBusan47392Republic of Korea Department of Chemistry University of EducationHo Chi Minh City700000Viet Nam Faculty of Pharmacy Ton Duc Thang UniversityHo Chi Minh City700000Viet Nam

The spread of tuberculosis(TB),especially multidrug-resistant TB and extensively drug-resistant TB,has strongly motivated the research and development of new anti-TB *** strategies to facilitate drug combinations,including pharmacokinetics-guided dose optimization and toxicology studies of first-and second-line anti-TB drugs have also been introduced and *** chromatography-mass spectrometry(LC-MS)has arguably become the gold standard in the analysis of both endo-and exo-genous *** technique has been applied successfully not only for therapeutic drug monitoring(TDM)but also for pharmacometabolomics *** improves the effectiveness of treatment,reduces adverse drug reactions,and the likelihood of drug resistance development in TB patients by determining dosage regimens that produce concentrations within the therapeutic target *** on TDM,the dose would be optimized individually to achieve favorable *** is essential in generating and validating hypotheses regarding the metabolism of anti-TB drugs,aiding in the discovery of potential biomarkers for TB diagnostics,treatment monitoring,and outcome *** article highlighted the current progresses in TDM of anti-TB drugs based on LC-MS bioassay in the last two ***,we discussed the advantages and disadvantages of this technique in practical *** pressing need for non-invasive sampling approaches and stability studies of anti-TB drugs was ***,we provided perspectives on the prospects of combining LC-MS-based TDM and pharmacometabolomics with other advanced strategies(pharmacometrics,drug and vaccine developments,machine learning/artificial intelligence,among others)to encapsulate in an all-inclusive approach to improve treatment outcomes of TB patients.

关键词： Tuberculosis Therapeutic drug monitoring LC-MS MIPD Pharmacometabolomics Precision medicine

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Numerical Solutions for Optimal Control of Stochastic Kolmogorov Systems

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Journal of Systems Science & Complexity 2021年第5期34卷 1703-1722页

作者： YIN George WEN Zhexin QIAN Hongjiang nguyen huy Department of Mathematics University of ConnecticutStorrsCT 06269USA School of Mathematics and Statistics Central South UniversityChangsha 410083China Department of Mathematics Wayne State UniversityDetroitMI 48202USA

This work is concerned with controlled stochastic Kolmogorov *** systems have received much attention recently owing to the wide range of applications in biology and *** with the basic premise that the underlying system has an optimal control,this paper is devoted to designing numerical methods for *** from the existing literature on numerical methods for stochastic controls,the Kolmogorov systems take values in the first *** is,each component of the state is *** work is designing an appropriate discrete-time controlled Markov chain to be in line with(locally consistent)the controlled *** authors demonstrate that the Kushner and Dupuis Markov chain approximation method still *** of the numerical scheme is proved under suitable conditions.

关键词： Controlled diffusion controlled Markov chain Kolmogorov equation numerical approximation

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