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Ha-Linh Quach,Thai Quang Pham,Ngoc-Anh Hoang,Dinh Cong Phung,Viet-Cuong Nguyen,Son Hong Le,Thanh Cong Le,Dang Hai Le,Anh Duc Dang,Duong Nhu Tran,Nghia Duy Ngu,Florian Vogt,Cong-Khanh Nguyen 대한의료정보학회 2022 Healthcare Informatics Research Vol.28 No.4
Objectives: Online misinformation has reached unprecedented levels during the coronavirus disease 2019 (COVID-19) pandemic. This study analyzed the magnitude and sentiment dynamics of misinformation and unverified information about public health interventions during a COVID-19 outbreak in Da Nang, Vietnam, between July and September 2020. Methods: We analyzed user-generated online information about five public health interventions during the Da Nang outbreak. We compared the volume, source, sentiment polarity, and engagements of online posts before, during, and after the outbreak using negative binomial and logistic regression, and assessed the content validity of the 500 most influential posts. Results: Most of the 54,528 online posts included were generated during the outbreak (n = 46,035; 84.42%) and by online newspapers (n = 32,034; 58.75%). Among the 500 most influential posts, 316 (63.20%) contained genuine information, 10 (2.00%) contained misinformation, 152 (30.40%) were non-factual opinions, and 22 (4.40%) contained unverifiable information. All misinformation posts were made during the outbreak, mostly on social media, and were predominantly negative. Higher levels of engagement were observed for information that was unverifiable (incidence relative risk [IRR] = 2.83; 95% confidence interval [CI], 1.33–0.62), posted during the outbreak (before: IRR = 0.15; 95% CI, 0.07–0.35; after: IRR = 0.46; 95% CI, 0.34-0.63), and with negative sentiment (IRR = 1.84; 95% CI, 1.23–2.75). Negatively toned posts were more likely to be misinformation (odds ratio [OR] = 9.59; 95% CI, 1.20–76.70) or unverified (OR = 5.03; 95% CI, 1.66–15.24). Conclusions: Misinformation and unverified information during the outbreak showed clustering, with social media being particularly affected. This indepth assessment demonstrates the value of analyzing online “infodemics” to inform public health responses.
Dual-band isotropic metamaterial absorber based on near-field interaction in the Ku band
The Linh Pham,Hong Tiep Dinh,Dinh Hai Le,Xuan Khuyen Bui,Son Tung Bui,Hong Luu Dang,Anh Duc Phan,Dac Tuyen Le,Dinh-Lam Vu 한국물리학회 2020 Current Applied Physics Vol.20 No.2
We numerically and experimentally investigate single-band and dual-band isotropic metamaterial absorbers (IMAs) based on metallic disks. By optimizing the diameter of the metallic disks and the thickness of the dielectric substrate, the single-band IMA is observed at 16.2 GHz with absorptivity of 97%. When adding one diskpair to the structure, the dual-band IMA is obtained at 12.8 and 15.5 GHz due to the symmetry breaking. The physical mechanics is explained by near-field coupling effect and equivalent LC circuit model. The measurement results performed in the range 12–18 GHz show a good agreement with simulation and theoretical analysis. Our findings demonstrate a new approach to achieve dual-band and multi-band IMAs.
Dinh, To Xuan,Thuy, Le Khac,Tien, Nguyen Thanh,Dang, Tri Dung,Ho, Cong Minh,Truong, Hoai Vu Anh,Dao, Hoang Vu,Do, Tri Cuong,Ahn, Kyoung Kwan The Korean Society for Fluid Power and Constructio 2019 드라이브·컨트롤 Vol.16 No.2
Fuel cell hybrid electric vehicle is an attractive solution to reduce pollutants, such as noise and carbon dioxide emission. This study presents an approach for energy management and control algorithm based on energetic macroscopic representation for a fuel cell hybrid electric vehicle that is powered by proton exchange membrane fuel cell, battery and supercapacitor. First, the detailed model of the fuel cell hybrid electric vehicle, including fuel cell, battery, supercapacitor, DC-DC converters and powertrain system, are built on the energetic macroscopic representation. Next, the power management strategy was applied to manage the energy among the three power sources. Moreover, the control scheme that was based on back-stepping sliding mode control and inversed-model control techniques were deduced. Simulation tests that used a worldwide harmonized light vehicle test procedure standard driving cycle showed the effectiveness of the proposed control method.
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.
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.
Efficacy of electrochemically activated water solution in gingivitis treatment
Dinh‑Toi Chu,Van‑Huy Pham,Thien Chu‑Dinh,Truong Nhu Ngoc Vo,Duc Long Duong,Van Nhon Bui,Minh Son Tong,Thi Thu Phuong Nguyen,Quynh Anh Le,Khanh‑Hoang Nguyen 한국약제학회 2019 Journal of Pharmaceutical Investigation Vol.49 No.3
Mouthwash is one of the most commonly oral healthcare products for prevention and treatment of gum diseases. Dr. ECA is a disinfectant solution manufactured by a Vietnamese company and has been licensed for oral healthcare, but its effect on gingivitis is still unclear. To evaluate the effectiveness of this product in the treatment of gingivitis, we conducted a clinical study in 60 students diagnosed with gingivitis to compare the results of gingivitis treatment using Dr. ECA and a control mouthwash (a demonstrated anti-gingivitis product). The data showed that in the treated group, the rate of good Gingivitis Index (GI) before treatment was 46.67%, but after 2 and 4 weeks of using Dr. ECA that rate was increased to 96.67% and 100%, respectively. The percentage of patients with bleeding on probing was 63.33% but declined sharply after 2 weeks of treatment to 6.67%, and further reduced to 3.33% after 4 weeks of treatment. The treatment outcomes in were similar in the Dr. ECA treated group and control one with no statistically significant difference. Our results suggest that the electrolyte saline solution Dr. ECA is effective in treating gingivitis. Its effects are similar to other mouthwash products that had been approved and marketed.
New look at secure performance of massive MIMO with low-resolution DACs
Anh-Tu Le,Dinh-Thuan Do,Nhu-Ngoc Dao,Nhan Duc Nguyen,Adão Silva 한국통신학회 2023 ICT Express Vol.9 No.4
Since the requirement of secure transmission for massive multiple-input–multiple-output (mIMO) is high, we consider a secure massive MIMO system in presence of multiple digital to analog converters (DACs). We deal with complicated performance analysis of the proposed system including a base station, a legitimate user, and an eavesdropper while these nodes are equipped with multiple antennas. In particular, we intend to present the closed-form expression for the ergodic secrecy rate of the system and also calculate the optimal power allocation for better performance gain. The simulation analysis shows that quantization bits, transmit signal to noise ratio at the base station, and power allocation plays a major role in enhancing the performance of the system.
Linh, Dinh Chi,Thanh, Tran Dang,Anh, Le Hai,Dao, Van Duong,Piao, Hong-Guang,Yu, Seong-Cho Elsevier 2017 JOURNAL OF ALLOYS AND COMPOUNDS Vol.725 No.-
<P><B>Abstract</B></P> <P>Influence of alkaline earth element doping in the A-site on the structure, magnetic and magnetocaloric properties of La<SUB>0.7</SUB>Ca<SUB>0.3-x</SUB>A<SUB>x</SUB>MnO<SUB>3</SUB> (A = Sr and Ba; <I>x</I> = 0, 0.15 and 0.3) perovskite manganites have been investigated. X-ray diffraction data indicates that samples <I>x</I> = 0 and 0.15 crystallize in the orthorhombic structure (space group <I>Pnma</I>), whereas samples <I>x</I> = 0.3 belong to the rhombohedral structure (space group <I>R</I>-3<I>c</I>). Substitution of Sr or Ba for Ca plays an important role in the increase of Curie temperature (<I>T</I> <SUB>C</SUB>) and modification the nature of the magnetic phase transition in materials. Sample <I>x</I> = 0 exhibits the first-order phase transition (FOPT) with a large magnetic entropy change (Δ<I>S</I> <SUB>m</SUB>), whereas samples <I>x</I> = 0.15 and 0.3 exhibit the second-order phase transition (SOPT) characterizations and the moderate values of Δ<I>S</I> <SUB>m</SUB>. Using the modified Arrott plots method, the critical behaviors around <I>T</I> <SUB>C</SUB> for SOPT samples have been investigated through the values of critical parameters (<I>T</I> <SUB>C</SUB>, <I>β</I>, <I>γ</I>, and <I>δ</I>). We pointed out that Ba-doping favors establishing long-range ferromagnetic order, contrary to the case of Sr-doping.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Sr or Ba-doped La<SUB>0.7</SUB>Ca<SUB>0.3</SUB>MnO<SUB>3</SUB> leads to modify the nature of the phase transition. </LI> <LI> Ba-doping favors establishing long-range FM order, contrast with Sr-doping. </LI> <LI> The effective exponents vary non-monotonically in the asymptotic region. </LI> </UL> </P>