Ocean-based electricity generating system utilizing the electrochemical conversion of wave energy by ionic polymer-metal composites

Vinh, Nguyen Duy,Kim, Hyung-Man Elsevier Inc. 2017 Electrochemistry Communications Vol.75 No.-

<P><B>Abstract</B></P> <P>In this research we used an energy harvesting system based on ionic polymer–metal composites (IPMCs) to absorb the kinetic energy of the ocean waves and generate electricity. The experimental results showed that IPMC materials have many advantages, including softness and durability; they also respond rapidly to wave parameters such as frequency, amplitude, and wavelength. In addition, the 296-day recorded data showed that the average power density generated each day remained stable at approximately 245μW/m<SUP>2</SUP>, the degradation of the IPMC's electrical performance in long-term operation being trivial.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Optimization of energy harvesting system design using IPMC for performance enhancement. </LI> <LI> Numerical studies of the energy harvesting system using IPMC materials operating in the ocean. </LI> <LI> Experiments matched to the optimized conditions to analyze energy system performance. </LI> <LI> The average power density at a given time of the day oscillated above 180μW/m<SUP>2</SUP>. </LI> <LI> Prevention of the growth of algae and barnacles contributes to improved system performance. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Enhancement of PEM Fuel Cell Performance by Flow Control

Duy, Vinh Nguyen,Lee, Jung Koo,Park, Ki Won,Kim, Hyung Man Trans Tech Publications, Ltd. 2015 Materials science forum Vol.804 No.-

<P>Flow-field design affects directly to the PEM fuel cell performance. This study aims to stimulate the under-rib convection by adding sub-channels and by-passes to the conventional-advanced serpentine flow-field to improve the PEM fuel cell performance. The experimental results show that if reacting gases flow in the same direction as the neighboring main channels, the under-rib convection shows a flow from the main channels to the sub-channels makes progress in reducing pressure drop and enhancing uniform gas supply and water diffusion. Alternatively, if in the direction opposite to that of the neighboring main channels, the under-rib convection shows a flow from the inlet side towards the outlet side across the sub-channel as in the conventional serpentine channels. Analyses of the local transport phenomena in the cell suggest that the inlet by-pass supplies the reacting gases uniformly from the entrance into the sub-channels and the outlet by-pass enhances water removal. Novel serpentine flow-field pattern employing sub-channels and by-passes shows uniform current density and temperature distribution by uniformly supplying the reacting gas. Furthermore, performance improvement of around 20% is observed from the experimental performance evaluation. As a result, longer battery life is expected by reducing the mechanical stress of membrane electrode assembly.</P>

Re-examination of Energy-Loss Straggling Calculations of Alpha Particles at 5.486 MeV

Nguyen Ngoc Duy,Nguyen Kim Uyen,Vinh N. T. Pham 한국물리학회 2020 New Physics: Sae Mulli Vol.70 No.2

We report on an evaluation of energy-loss straggling calculations performed using the LISE++ code and theoretical models. The energy-loss straggling of the alpha particles at 5.486 MeV in Al, Cu, Ag, Tb, Ta, and Au was calculated by using the LISE++ code and the Titeica model. The results of the calculations were compared to the measured data to improve the accuracy of the straggling predictions. The results show that the straggling is increased by the energy loss at a rate of 8.0 keV/%. The uncertainties of the LISE++ and Titeica calculations were reduced to about 15% by adding fitting parameters. We also propose a new semi-empirical formula which well reproduces the measured data with an uncertainty of about 20% for 5.486-MeV alpha particles in the materials used in the research.

An Approximation of the Synthesis Cross Section for the Unknown 126th Element via 58Ni + 251Cf and 64Zn + 248Cm Combinations

Duy Nguyen Ngoc,Ho Phuong-Thao,Pham Vinh N. T.,Hoan Nguyen Thi Thu 한국물리학회 2020 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.77 No.1

In this paper, we estimate the production cross section of the unknown super-heavy nuclei 309, 312126 via 58Ni + 251Cf and 64Zn + 248Cm combinations by using approximation methods. For each reaction, the competition between compound nucleus (CN) formation and quasi-fission process is also analyzed. We found that the synthesis cross section for the 309126 isotope is about 3 fb, which is about 5 orders of magnitude higher than that for the 312126 nucleus. The results also suggest that a valley exists around the isotope with A = 313 in the production yields for the 126th element. Moreover, the synthesis of the 310-317126 isotopes is still a challenge for experimental techniques due to the small cross sections, which are less than 1 fb.

A Numerical Calculation of the Nuclear Spin-Parity and Magnetic Moment Based on the Single-Particle Shell Model

Nguyen Ngoc Duy,Latsamy Xayavong,Nguyen Kim Uyen,Vinh Nguyen Thanh Pham,Tran Viet Nhan Hao 한국물리학회 2019 새물리 Vol.69 No.10

Nuclear physics is an obligatory subject for the general physics program of undergraduates in most of the natural science universities worldwide. In nuclear physics, the shell model is one of the most important models, and is well used to determine the spin-parity and the magnetic moment of a nucleus. Over ten years of teaching general physics, we have realize that most undergraduate students find calculating these parameters by using this shell model to be difficult due to the classification of the subshells and the intrinsic spin of nucleons. With the hope to help these students, in the present study, we introduce a graphical-user-interface (GUI) program to execute our selfdeveloped Shell Model Calculator (SMC) code written in the Visual Basic 6.0 (VB6) programming language. Our SMC validation results for the quantum quantities in a series of nuclei Z = 1 - 20 were compared with experimental data and found to be in good agreement. In general, we successfully developed an SMC program that can be used for teaching, learning, and researching nuclear physics in universities.

Prediction of the Spin-Parities and the Magnetic Moments for the Ground States of Proton-rich Nuclei with Z = 21–30

Ly Nguyen Duy,Xayavong Latsamy,Uyen Nguyen Kim,Pham Vinh N. T.,Hao T. V. Nhan,Duy Nguyen Ngoc 한국물리학회 2020 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.77 No.11

The present paper reports on the spin-parities and the magnetic moments for the ground states of 44 proton-rich isotopes with Z = 21-30 and A = 36-57, which are important for studies of either reaction rates in X-ray bursts or nuclear structure. These nuclear properties were calculated based on the single-particle shell model. The spins of the concerned nuclei were compared to available experimental data adopted from the NuDat database to evaluate the variations in the astrophysical rates of the rp-process reactions. We found discrepancies, due to the deformed nuclear structure, between the present results and those reported in the NuDat database. The spin uncertainties result in large variations, 13% - 200%, in the astrophysical rates of the rp-process reactions. In particular, the spin uncertainties of the 44V and the 46-49Mn isotopes significantly affect the astrophysical rates of the reverse reactions of the proton captures 43Ti(p,γ)44V$(p,γ)45Cr, 45Cr(p,γ)46Mn(p,γ)47Fe, 47Mn(p,γ)48Fe, 47Cr(p,γ)48Mn(p,γ)49Fe, and 48Cr(p,γ)49Mn(p,γ)50Fe. Moreover, the magnetic moments of most of the isotopes were predicted for the first time. The results show that the magnetic moments are in the order of μp(1f7/2) > μp(2p3/2) > μn(1d3/2)> μn(1f7/2) for the nuclei having an unpaired nucleon in the proton/neutron shells. The present study suggests that reliable calculations and/or measurements for the properties of proton-rich nuclei are highly demanded.

Key Determinants of Repurchase Intention toward Organic Cosmetics

Phuong Ngoc Duy NGUYEN,Vinh Tan NGUYEN,Nguyen Ngoc Thao VO 한국유통과학회 2019 The Journal of Asian Finance, Economics and Busine Vol.6 No.3

This paper aims to discover factors and their influences degree to repurchase organic cosmetic in Vietnam. In addition, this research also discloses the main segments that have high demand re-buying intention based on demographic groups of gender, age, income, educational level, job, type of products, and place of production. Twenty-eight scale was designed based on previous studies and adjusted to match the 5-point Likert scale to conduct measurement. By using survey method to test hypotheses and set up conceptual models to collect 295 Vietnamese consumers who have experience in consuming organic cosmetic by explain the results through Smart PLS software. The findings show that there is positive attitude of customers to the intention of acquiring organic cosmetics, green perceived and customer satisfaction. In addition, customer satisfaction, knowledge of products, safety values, and environmental protection consciousness also play important roles to form a positive attitude of customers for products. Moreover, the consciousness of green living of consumers accounts for a high proportion in creating customer satisfaction for organic products. The results show useful information for current premises to determine the factors that influence the decision to repurchase organic cosmetic product, that provide business strategies.

A study on emission and fuel consumption of motorcycles in idle mode and the impacts on air quality in Hanoi, Vietnam

Yen-Lien T. Nguyen,Anh-Tuan Le,Khanh Nguyen Duc,Vinh Nguyen Duy,Cong Doan Nguyen 서울시립대학교 도시과학연구원 2021 도시과학국제저널 Vol.25 No.4

This study aims to develop the models of emission and fuel consumption during idling of motorcycles (MCs) in Hanoi, including the unsteady and steady idling stages. Five MC models commonly used in Hanoi were selected to measure the instantaneous emission and fuel consumption rates under the controlled conditions at the laboratory conditions. The instantaneous emission and fuel consumption models during idling were developed for the test MCs in the unsteady idling stage. The R2 of obtained models are higher than 0.9. The average emission and fuel consumption rates in the steady idling stages were determined. The average idling emissions of pollutants CO, CO2, HC and NOx were 60.9, 534.3, 10.3 and 1.8 g/h, respectively. The average fuel loss during idling is around 180 g/h. The emission released from the MC fleet in Hanoi during idling was estimated for the year 2018. The total idling emissions from the MC fleet of 3.9 million vehicles in the year 2018 of CO, CO2, HC and NOx were 6.5, 57.1, 1.1 and 0.2 kt, respectively. The total fuel loss during idling of the MC fleet in 2018 was ∼19.3 kt. The air pollutants eliminated in the idle mode as CO, CO2, HC and NOx contributed 2.23%, 3.19%, 1.14% and 1.03%, respectively, of the total emission from the MC fleet in Hanoi.

Effects of Foreign Direct Investment and Human Capital on Labour Productivity: Evidence from Vietnam

Nguyen Hoang LE,Luong Vinh Quoc DUY,Bui Hoang NGOC 한국유통과학회 2019 The Journal of Asian Finance, Economics and Busine Vol.6 No.3

The paper aims to investigate whether foreign direct investment (FDI) has positive effect on the labour productivity in Vietnam. Labour productivity is the elemental determinant of a country’s development level in long-term. In recent years, although increasing consistently, labour productivity of Vietnam remains low in comparison to other South East Asian countries. To identify the direction of effect and the level of effect of FDI and human capital on the labour productivity of Vietnam, Autoregressive Distributed Lag (ARDL) model was used to examine the effect of FDI and human capital on labour productivity in Vietnam from 1986 to 2014. The results of bounds test confirm the existence of cointegration among the variables. Further, the Toda and Yamamoto Granger causality test affirms that there is unidirectional causality running from foreign direct investment and human capital index to labour productivity. The empirical results provide strong statistical evidence that foreign direct investment and human capital has a positive impact on labour productivity in Vietnam in long-term. These findings imply that workers are expected to further improve their knowledge, skills and that policy-maker should establish concrete plans to increase human capital. Results from this study provide suggestion necessary for Vietnam to achieve sustainable development.

Electrical Conduction and Resistance Switching Mechanisms of Ag/ZnO/Ti Structure

Nguyen, Trung Do,Pham, Kim Ngoc,Tran, Vinh Cao,TuanNguyen, Duy Anh,Phan, Bach Thang Institute of Korean Electrical and Electronics Eng 2013 전기전자학회논문지 Vol.17 No.3

We investigated electrical conduction and resistance switching behavior of the Ag/ZnO/Ti structures for random access memory devices. These films were prepared on glass substrate by dc sputtering technique at room temperature. The resistance switching follows unipolar switching mode with small switching voltages (0.4 V - 0.6 V). Two electrical conduction mechanisms dominating the LRS and HRS are Ohmic and trap-controlled space charge limited current, respectively. These both conductions are consistent with the filamentary model. Based on the filamentary model, the switching mechanism was also interpreted.