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Anh Tuan DINH,Phung Quang NGUYEN,Minh-Duc LE 제어로봇시스템학회 2010 제어로봇시스템학회 국제학술대회 논문집 Vol.2010 No.10
Control of Inductor Motors is a difficult task because of the motors’ non-linear nature. Hence, the Inductor Motors are usually expressed by complicated non-linear models. This paper presents a new and effective method for modeling stator current and estimating rotor flux of an induction motor by applying Direct?ecoupling Methodology. A nonlinear control approach with full state feedback linearization has been used to construct the decoupling form of the induction motors. A new current controller named “irect-decoupling” based on exact linearization algorithm of the motor current model has been proposed. The obtained linear system in a new state-space is very convenient to design the current controller and the rotor flux estimator for induction motors. A linear Kalman filter has also been derived to construct an observer for rotor flux. Effectiveness of the new adaptive backstepping controller for induction motors and Kalman filter for observation of rotor flux has been verified by simulations and experiments in wide ranges of motor speed. Simulations and experiment results show clearly that the rotor flux can be well estimated in all operating conditions and performance of induction motors under all dynamic modes can be improved by using the new developed controller.
Anh-Tuan Le,P.T. Huy,Phuong Dinh Tam,Tran Quang Huy,A.A. Kudrinskiy,Yu A. Krutyakov 한국물리학회 2010 Current Applied Physics Vol.10 No.3
In this article, we represent a versatile and effective technique which using non-toxic chemicals to prepare stable aqueous dispersions of silver nanoparticles (NPs) via modified Tollens process. It was shown that as-prepared silver colloids consisted of finely-dispersed NPs with average diameter about 10 nm and a relatively narrow size distribution. Moreover, they could be stored very stable after several months without observation of aggregates or sedimentation. In comparison with previous works where Tollens process was being used, we for the first time applied UV-irradiation simultaneously with glucose reduction of silver salt through NPs preparation. The colloidal solutions of silver NPs were found to exhibit a high antibacterial activity against gram-negative Escherichia coli. The concentration of silver leading to a complete inhibition of bacteria growth was revealed as low as at 1.0 ㎍ml-1 and found much lower compared to earlier reports. These advantages of aqueous dispersions of silver NPs make them ideal for green industrial, medicinal, microbiological and other applications.
Nguyen Duc Anh,Pham Van Thanh,Doan Tu Lap,Nguyen Tuan Khai,Tran Van An,Tran Duc Tan,Nguyen Huu An,Dang Nhu Dinh 한국인터넷정보학회 2022 KSII Transactions on Internet and Information Syst Vol.16 No.2
Forest fires inflict great losses of human lives and serious damages to ecological systems. Hence, numerous fire detection methods have been proposed, one of which is fire detection based on sensors. However, these methods reveal several limitations when applied in large spaces like forests such as high cost, high level of false alarm, limited battery capacity, and other problems. In this research, we propose a novel forest fire detection method based on image processing and correlation coefficient. Firstly, two fire detection conditions are applied in RGB color space to distinguish between fire pixels and the background. Secondly, the image is converted from RGB to YCbCr color space with two fire detection conditions being applied in this color space. Finally, the correlation coefficient is used to distinguish between fires and objects with fire-like colors. Our proposed algorithm is tested and evaluated on eleven fire and non-fire videos collected from the internet and achieves up to 95.87% and 97.89% of F-score and accuracy respectively in performance evaluation.
The Study of Mach Waves Generated by a Roughness Element
Hoang Quan Dinh,Anh Tuan Nguyen,Ivan Vladimirovich Egorov,Ngoc Hai Duong 한국항공우주학회 2022 International Journal of Aeronautical and Space Sc Vol.23 No.3
In this paper, a simplified inviscid boundary condition is applied to solve the problem of Mach waves generated by a roughness element on the wall surface of a supersonic wind tunnel. The geometry of the roughness element is simplified by a parabolic function, to which mathematical formulas are introduced to model the boundary condition. These techniques help simplify the problem and minimize the required computer resources for the simulation performance. Using the direct numerical simulation (DNS) method while employing the above-mentioned techniques, the authors can simulate the generation and the propagation of Mach waves from a roughness element at a Mach number of 2.5. The result shows that a pair of Mach waves are generated at the leading and trailing edges of the roughness element and oscillate with small amplitudes. We also study the effect of the height of the element, the flow speed, the Reynolds number, and the unsteadiness of the flow on the simulation result. The numerical result is compared with published experimental data for the validation.
Duc, Nguyen Dinh,Seung-Eock, Kim,Cong, Pham Hong,Anh, Nguyen Tuan,Khoa, Nguyen Dinh Elsevier 2017 International journal of mechanical sciences Vol.133 No.-
<P><B>Abstract</B></P> <P>The purpose of the present study is to investigate dynamic response and vibration of composite double curved shallow shells with negative Poisson's ratios in auxetic honeycombs core layer on elastic foundations subjected to blast and damping loads using analytical solution. This study considers composite double curved shallow shells with auxetic core which have three layers in which the top and bottom outer skins are isotropic aluminum materials; the central layer has honeycomb structure using the same aluminum material. Based on the first order shear deformation theory (FSDT) with the geometrical nonlinear in von Karman and using Airy stress functions method, Galerkin method and the fourth-order Runge–Kutta method, the resulting equations are solved to obtain expressions for nonlinear motion equations. The effects of geometrical parameters, material properties, elastic foundations Winkler and Pasternak, the nonlinear dynamic analysis and vibration of double curved shallow shells with negative Poisson's ratios in auxetic honeycombs core layer are studied.</P> <P><B>Highlights</B></P> <P> <UL> <LI> To investigate dynamic response and vibration of composite double curved shallow shells by using analytical solution. </LI> <LI> The composite shells have the central auxetic core layer—honeycomb structures with negative Poisson's ratio. </LI> <LI> Based on the first order shear deformation theory (FSDT). </LI> <LI> Used airy stress functions, Galerkin method and fourth-order Runge–Kutta method. </LI> <LI> The effects of geometrical parameters, material properties, elastic Winkler and Pasternak foundations, mechanical and blast loads are studied. </LI> </UL> </P>
The Factors Affecting Corporate Income Tax Non-Compliance: A Case Study in Vietnam
NGUYEN, Loan Thi,NGUYEN, Anh Hong Viet,LE, Hac Dinh,LE, Anh Hoang,TRUONG, Tu Tuan Vu Korea Distribution Science Association 2020 The Journal of Asian Finance, Economics and Busine Vol.7 No.8
In many countries, the Government enacts tax laws in order to manage tax collection and regulate the macro-economy. According to Noor, Jamaludin, Omar, and Aziz (2013), tax non-compliance is a growing concern because of its negative effects on the state budget. The main objectives of this article are to identify the factors affecting corporate income tax non-compliance of enterprises in Ho Chi Minh City in accordance with the current situation of Vietnamese tax administration. We use several research methods, including the exploitation of information and practical experiences from both taxpayers and tax authorities; with Probit regression model on a sample of 187 enterprises that have been inspected or examined by tax authorities in Vietnam during the period from 2013 to 2017.The article identified eight factors affecting corporate income tax (CIT) non-compliance: (1) working capital/total assets; (2) revenue/total assets; (3) total debt/total assets; (4) loss in the previous year; (5) receivables/revenue; (6) the size of enterprises; (7) tax administrative penalties/tax payable; and (8) business field. In particular, the tax non-compliance was studied as a violation of Vietnamese tax laws by enterprises declaring an insufficient amount of CIT payable to the State budget.
Quan T. Lai,Vu Anh Tuan,Dinh Kim Dieu,Alexander B. Orfinger,Ngo Minh Ly,Nguyen Thanh Ha,Trinh Truong Giang 한국해양과학기술원 2022 Ocean science journal Vol.57 No.4
This study aimed to analyze the sex ratio, spawning seasons, length at first maturity, length distribution, length–weight relationship, and relative condition factor of Cultellus maximus (Gmelin, 1791) in Southern Vietnam. A total of 1037 individuals of C. maximus were collected at 3 sampling sites from June, 2019 to June, 2020. The sex ratio was found to be female biased in Can Gio and male biased in Phu Tan and Ngoc Hien. The clam spawns throughout the year, peaking at Q2 and Q3 during the rainy season. Pooled length at first maturity was 10.12 cm (9.65–10.49 cm CI 95%, P-value < 2.2·10–16). The length–weight relationship indicates positive allometric growth. This study suggests that imposing a minimum harvest size limit on C. maximus using the length at first maturity as reference and with harvest seasons in Q1 in Ngoc Hien and Can Gio and Q2 or Q3 in Phu Tan would be ideal for consumption of this species.
Tam-Thanh Pham,Anh-Tuan Dinh,Hong-Ha Tran,Dang-Khanh Le 대한전자공학회 2019 IEIE Transactions on Smart Processing & Computing Vol.8 No.3
In this paper, we consider a cooperative cognitive radio network with multiple relays under an eavesdropping attack. We first propose a novel relay selection scheme to improve network security and reliability. Then, we derive accurate closed-form expressions of the network outage and intercept probabilities. Finally, several representative simulation results are provided to validate our analyses. We show that network reliability is completely irrelevant to the channels’ statistical characteristics between relays and the eavesdropper, while network security is independent of the channel statistical characteristics for relays to the destination. We also point out that network security is first improved from increasing the number of relays; however, when the number of relays reaches a certain point, the increased network reliability is not proportional to the number of relays any more.
Nguyen Thi Thuy,Phuong Dinh Tam,Mai Anh Tuan,Anh-Tuan Le,Le Thi Tam,Vu Van Thu,Nguyen Van Hieu,Nguyen Duc Chien 한국물리학회 2012 Current Applied Physics Vol.12 No.6
The present paper introduces a facile and cost-effective route for the direct dispersion of multi-walled carbon nanotubes (MWCNTs) in DNA solution. Their application in detecting Escherichia coli O157:H7using DNA biosensorwas demonstrated. The dispersion state of theMWCNTswas characterized via UVeVis spectroscopy, transmission electron microscopy, and field emission scanning electron microscopy. The interaction between DNA sequence and the MWCNTs was investigated using Raman spectroscopy and Fourier transform infrared spectroscopy. As-obtainedMWCNT solutionwas used in the preparation of DNA sensor. Results revealed that the developed DNA sensor can detect a DNA target as low as 1 nM in a buffer solution. The sensitivity of the DNA sensor reached approximately 0.19 nM/mV. The effect of dispersion parameters, including pH values, DNA concentration, ion strength, and sonication time, on sensor response was also studied. TheDNA sensor can respondwell to 120 min of sonication time, a pH value of 9, and 20 mM of DNA sequence concentration. The results of the present study showed a potential application of the DNA sensor in the detection of Escherichia coli O157:H7.
Thanh-Tung Duong,Ta Quoc Tuan,Dang Viet Anh Dung,Nguyen Van Quy,Dinh-Lam Vu,Man Hoai Nam,Nguyen Duc Chien,윤순길,Anh-Tuan Le 한국물리학회 2014 Current Applied Physics Vol.14 No.12
Polyaniline nanowires (PANI NWs) were deposited onto fluorine-doped tin oxide (FTO) glass substrate using the cyclic voltammetric method with aniline monomer precursor in HCl aqueous solution. The secondary oxidation peak plays an important role in polymerization of aniline monomer and the optimization of catalytic activity of PANI-based counter electrodes was achieved by controlling the number of cycles. The photovoltaic performance of the dye-sensitized solar cells (DSSCs) with PANI NWs counter electrodes (CEs) was optimized at 4th cycles, and then following parameters were obtained: Jsc ¼ 17.2 mA cm2, Voc ¼ 0.71 V, FF ¼ 59.3%, and efficiency (h) ¼ 7.24%. While, Jsc ¼ 14.7 mA cm2, Voc ¼ 0.77 V, FF ¼ 70.6%, and efficiency (h) ¼ 7.98% in cells with Pt CEs. The PANI NWs were attractive as an alternative CEs for the low-cost DSSCs instead of Pt.