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Pham V.-C.,National Cheng Kung University | Pham V.-C.,Lac Hong University | Juang J.-C.,National Cheng Kung University
Journal of Atmospheric and Solar-Terrestrial Physics | Year: 2015

Abel inversion techniques have been widely employed to retrieve electron density profiles (EDPs) from radio occultation (RO) measurements, which are available by observing Global Navigation Satellite System (GNSS) satellites from low-earth-orbit (LEO) satellites. It is well known that the ordinary Abel inversion might introduce errors in the retrieval of EDPs when the spherical symmetry assumption is violated. The error, however, is case-dependent; therefore it is desirable to associate an error index or correction coefficient with respect to each retrieved EDP. Several error indices have been proposed but they only deal with electron density at the F2 peak and suffer from some drawbacks. In this paper we propose an artificial neural network (ANN) based error correction method for EDPs obtained by the ordinary Abel inversion. The ANN is first trained to learn the relationship between vertical total electron content (TEC) measurements and retrieval errors at the F2 peak, 220. km and 110. km altitudes; correction coefficients are then estimated to correct the retrieved EDPs at these three altitudes. Experiments using the NeQuick2 model and real FORMOSAT-3/COSMIC RO geometry show that the proposed method outperforms existing ones. Real incoherent scatter radar (ISR) measurements at the Jicamarca Radio Observatory and the global TEC map provided by the International GNSS Service (IGS) are also used to valid the proposed method. © 2015.

Tran L.B.,Lac Hong University | Le T.H.,Ho Chi Minh City University of Technology
Proceedings - 2015 IEEE International Conference on Knowledge and Systems Engineering, KSE 2015 | Year: 2015

In this paper, the authors propose a personal authentication system using a combination of both face and fingerprint features. In the proposed system, face and fingerprint features are extracted by Zernike Moment (ZM), the extracted features are classified by Relevance Vector Machine (RVM), the generated matching scores are fused using sum rule. Experimental results on the FVC2004 DB4 and ORL databases show that RVM provides better accuracy compared to unit face or fingerprint recognition and existing fusion algorithms. With respect to SVM fusion, it is observed that, the accuracy of RVM and SVM are comparable, however, the time for RVM fusion is significantly reduced. © 2015 IEEE.

Nguyen L.T.L.,HCMC University of Technology | Nguyen C.V.,Lac Hong University | Dang G.H.,HCMC University of Technology | Le K.K.A.,HCMC University of Technology | Phan N.T.S.,HCMC University of Technology
Journal of Molecular Catalysis A: Chemical | Year: 2011

A highly porous metal-organic framework (IRMOF-8) was synthesized by a solvothermal method, and used as an efficient heterogeneous catalyst for the Friedel-Crafts acylation reaction. The solid catalyst was characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), atomic absorption spectrophotometry (AAS), and nitrogen physisorption measurements. High conversions were achieved in the presence of a catalytic amount of the IRMOF-8 (1-5 mol%) without the need for an inert atmosphere. The solid catalyst could be facilely separated from the reaction mixture by simple centrifugation, and could be reused without a significant degradation in catalytic activity. No contribution from homogeneous catalysis of active acid species leaching into the reaction solution was detected. © 2011 Elsevier B.V. All rights reserved.

Manh H.D.,Lac Hong University
Scientometrics | Year: 2015

This paper investigates Vietnam’s scientific publications between 1996 and 2013 from Scopus database, focusing on international collaboration. The total scientific output of the country increased about 16 publications per year during 1996–2001 and quickly increased 20 % per year during 2002–2013. However, the share of international collaboration was about 77 % of the total output. Biological and agricultural science, medicine dominated the total output, but 80–90 % of these publications are from international collaboration. In contrast, mathematics is the only field that domestic output is larger than collaboration output. Japan is the largest collaborating country, followed by United States, France, South Korea and United Kingdom. Analyzing titles of publications with these collaborating countries, we found high frequency of “Vietnam” or “Vietnamese” words. This result suggested that many study subjects of these research collaborations were from Vietnam. Furthermore, corresponding authors of these research collaborations are mainly from collaborating countries, which suggested that these research collaborations mainly led by foreign authors. Although the total output was quickly increased, especially collaboration output, Vietnamese researchers should be aware about their low contribution to these collaborations. © 2015 Akadémiai Kiadó, Budapest, Hungary

Long T.B.,Lac Hong University | Thai L.H.,Ho Chi Minh City University of Natural Sciences | Hanh T.,Lac Hong University
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2012

In this paper, the authors present a multimodal biometric system using face and fingerprint features with the incorporation of Zernike Moment (ZM) and Radial Basis Function (RBF) Neural Network for personal authentication. It has been proven that face authentication is fast but not reliable while fingerprint authentication is reliable but inefficient in database retrieval. With regard to this fact, our proposed system has been developed in such a way that it can overcome the limitations of those uni-modal biometric systems and can tolerate local variations in the face or fingerprint image of an individual. The experimental results demonstrate that our proposed method can assure a higher level of forge resistance in comparison to that of the systems with single biometric traits. © 2012 Springer-Verlag.

Cu T.S.,Vietnam Academy of Science and Technology | Cao V.D.,Lac Hong University | Nguyen C.K.,Vietnam Academy of Science and Technology | Tran N.Q.,Vietnam Academy of Science and Technology
Macromolecular Research | Year: 2014

In this paper, we report the preparation and stabilization of colloidal silver nanoparticle solution, with the assistance of chitosan dihydroxyphenyl acetamide (CDHPA), or oligochitosan dihydroxyphenyl acetamide (OCDHPA). The structure of the chitosan derivatives were characterized by nuclear magnetic resonance (1H NMR) spectroscopy. The morphology of the synthesized silver core-chitosan shell nanoparticles were observed by transmission electron microscopy (TEM) and X-ray diffraction (XRD) techniques, and showed a well-defined core-shell structure of polymer-coated silver nanoparticles (AgNPs). The core-shell NPs exhibited a strong antibacterial activity against E. coli and S. aureus, at a very low concentration of AgNPs (2.5 ppm). Our studies offer a new method for the preparation and protection of silver nanoparticles for antibacterial applications. [Figure not available: see fulltext.] © 2014 The Polymer Society of Korea and Springer Sciene+Business Media Dordrecht.

Kung Y.-S.,Southern Taiwan University of Science and Technology | Nguyen V.Q.,Southern Taiwan University of Science and Technology | Nguyen V.Q.,Lac Hong University | Huang C.-C.,Industrial Technology Research Institute of Taiwan | Huang L.-C.,Industrial Technology Research Institute of Taiwan
2011 IEEE Symposium on Industrial Electronics and Applications, ISIEA 2011 | Year: 2011

Based on Simulink/Modelsim co-simulation technology, the design of a sensorless control IP (Intellectual Property) for PMSM (Permanent Magnet Synchronous Motor) drive is presented in this paper. Firstly, a mathematical model for PMSM is derived and the vector control is adopted. Secondly, a rotor flux position is estimated by using a sliding mode observer (SMO). These estimated values are feed-backed to the current loop for vector control and to the speed loop for speed control. Thirdly, the Very-High-Speed IC Hardware Description Language (VHDL) is adopted to describe the behavior of the sensorless speed control IP which includes the circuits of space vector pulse width modulation (SVPWM), coordinate transformation, SMO, fuzzy controller, etc. Fourthly, the simulation work is performed by MATLAB/Simulink and ModelSim co-simulation mode, provided by Electronic Design Automation (EDA) Simulator Link. The PMSM, inverter and speed command are performed in Simulink and the sensorless speed control IP of PMSM drive is executed in ModelSim. Finally, the co-simulation results validate the effectiveness of the sensorless PMSM speed control system. © 2011 IEEE.

Shu M.-H.,National Kaohsiung University of Applied Sciences | Chiu C.-C.,National Kaohsiung University of Applied Sciences | Nguyen T.-L.,National Kaohsiung University of Applied Sciences | Nguyen T.-L.,Lac Hong University | Hsu B.-M.,Cheng Shiu University
Expert Systems with Applications | Year: 2014

For monitoring online manufacturing processes, the proportion of weights imposed on each type of product's defects (nonconformities or demerits) has a profoundly effective impact on control charts' performance. Apparently, the demerit-chart approach is superior than the widely-used c-chart scheme, because it allows us to place relative precise weights (real numbers) on defects according to their distinctly inferior degrees affecting the product quality so that the abnormal variations of processes can be literally exposed. However, in many applications, the seriousness of defects is evaluated partially or entirely by the inspectors' perceptive judgement or knowledge, so with the precise-weight assignment, the demerit rating mechanism is considered to be somewhat constrained and subjective which inevitably leads to the targeted manufacturing process with limited and possibly biased information for online surveillance. To cope with the drawback, a demerit-fuzzy rating system and monitoring scheme is proposed in this paper. We first incorporate fuzzy weights (fuzzy numbers) to properly reflect the severity measures of defects which are categorized linguistically. Then, based on properties of fuzzy set theory and proposed approaches for fuzzy-number ranking, we develop the demerit-fuzzy charting scheme which is capable of discriminating process conditions into multi-intermittent statuses between in-control and out-of-control. This approach improves the traditional process control techniques with the binary-classification restraint for the process conditions. Finally, the proposed demerit-fuzzy rating system, monitoring scheme, and classification is elucidated by an application in garment industry to monitor textile-stitching nonconformities conditions. © 2014 Elsevier Ltd. All rights reserved.

Wang C.-N.,National Kaohsiung University of Applied Sciences | Nguyen N.-T.,National Kaohsiung University of Applied Sciences | Nguyen N.-T.,Lac Hong University | Tran T.-T.,Lac Hong University
Scientific World Journal | Year: 2015

The growth of economy and population together with the higher demand in energy has created many concerns for the Indian electricity industry whose capacity is at 211 gigawatts mostly in coal-fired plants. Due to insufficient fuel supply, India suffers from a shortage of electricity generation, leading to rolling blackouts; thus, performance evaluation and ranking the industry turn into significant issues. By this study, we expect to evaluate the rankings of these companies under control of the Ministry of Power. Also, this research would like to test if there are any significant differences between the two DEA models: Malmquist nonradial and Malmquist radial. Then, one advance model of MPI would be chosen to see these companies' performance in recent years and next few years by using forecasting results of Grey system theory. Totally, the realistic data 14 are considered to be in this evaluation after the strict selection from the whole industry. The results found that all companies have not shown many abrupt changes on their scores, and it is always not consistently good or consistently standing out, which demonstrated the high applicable usability of the integrated methods. This integrated numerical research gives a better "past-present-future" insights into performance evaluation in Indian electricity industry. © 2015 Chia-Nan Wang et al.

Le D.-H.,Ton Duc Thang University | Nguyen K.-H.,Lac Hong University
Procedia Engineering | Year: 2016

The present study aims to investigate the fresh and hardening properties of a soil-based controlled low-strength material (CLSM) containing stainless steel slag as a cementitious material. This type of CLSM primarily uses in construction as a trench-fill material. Four levels of the cement substitution (i.e. 0%, 10%, 20%, and 30%) and three amounts of binder content (80-, 100-, and 130 kg/m3) were generated for the experimental work. Fresh and hardening properties of the recommended CLSM were examined in the laboratory. The results show that the proposed CLSM could be employed for eco- friendly trench fills. © 2016 The Authors. Published by Elsevier Ltd.

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