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Nguyen Van Minh,Yury Konyukhov,Gopalu Karunakaran,Dmitry Ryzhonkov,Tang Duong,Sergey Kotov,Denis Kuznetsov 대한금속·재료학회 2017 METALS AND MATERIALS International Vol.23 No.3
In the present study, the influence of nano additives (Ni, Fe) and different mixing (turbular and magnetic) on thedensification, microstructure and micro-hardness of the tungsten material under spark plasma sintering is analyzed. After turbulent mixing the nanoparticles are distributed widely in the W interparticle gaps but after magneticmixing the nanoparticles are distributed not only on the gaps of the W particles but also on the broken surfaces. Niincorporated tungsten materials achieved the maximum density of 98.3% at 1400 °C (turbular mixing) and 97.9%at 1300 °C (magnetic mixing). Fe incorporated tungsten material showed density of 97.7% at 1600 °C and 97.2%at 1400 °C after turbular and magnetic mixing. The influence of nanoparticles in the densification process wasexplained by Laplace force, boundary slip and Agte-Vacek effect. The microstructural analysis showed that nanomodificationreduced the degree of porosity, and provides a compact material at low temperatures. X-ray fluorescenceanalysis reveals that magnetic mixing shows more uniform distribution of nanoparticles than turbular mixing. Thenanoparticles incorporation increased the micro hardness of tungsten material. Hence, it is clear that magnetic mixingand nano modification greatly improved the densification and sintering behavior of the tungsten material.
On-line and Off-line Based Approximation Algorithm for Model Predictive Control of Hybrid Systems
Koichi Kobayashi,Nguyen Van Tang,Kunihiko Hiraishi 대한전자공학회 2008 ITC-CSCC :International Technical Conference on Ci Vol.2008 No.7
In this paper, a new approximate algorithm for model predictive control of hybrid systems is proposed. The proposed algorithm consists of the off-line computation and the on-line computation. In the off-line computation, lower and upper bounds of the optimal value of a given cost function for each mode sequence are calculated. In the on-line computation, after the mode sequence is decided by using off-line computation results, the finite-time optimal control problem, i.e., the quadratic programming problem is solved. So the reduction of the computation time in the on-line computation is achieved. In this paper, the effectiveness of the proposed algorithm is shown by a numerical example.
Factors Affecting Parents' Intention to Choose English Centers: The Role of STEM Education
Tran, Do-Van-Anh,Nguyen, Ngoc-Duyen,Tang, Thai-Ngoc,Le, Dinh-Bao-Nhi,Vo, Huyen-Yen-Nhi,Le, Hoanh-Su Korea Multimedia Society 2020 The journal of multimedia information system Vol.7 No.1
Parents' desire for daily English practice for students and the urge for a etter English education has led to a demand for a highly qualified educational curriculum. In addition to getting deep-dive insights into parents' decision-making process, the increasingly important role of STEM education method has been proved in accordance with plenty of evidenced-based many of previous research. This study was conducted to examine the five independent factors affecting parents' intentions when designating English centers for their children, respectively named: Facility, Teachers, Brands, Social factors and Tuition. Through a preliminary approach, 235 samples were analyzed. Analysis of the sample responses reveals the importance level of five independent factors affecting Parents' intention to choose English centers in descending order: Facilities, Teachers, Brands, Tuition and Social factors. Furthermore, a positive correlation was found between STEM and Intention to choose English centers, indicating that whether the center applies STEM-related curriculum in English courses or not, in fact, has a significant impact on parents' decision. In terms of attitude towards STEM, further statistical tests revealed an interesting finding, which is the fact that how STEM affects Intention of parents is directly proportional to the Attitude towards STEM. With the help of SPSS 20 and AMOS 20, the SEM analysis was processed in order to draw conclusions about factors impacting Intentions to choose English centers. Combining with Multi-group analysis, the major role of STEM education has been assessed in relation to plenty of correlations. In light of recent major and massive growth of English teaching market in Vietnam, several suggestions and recommendations in terms of sustainable developments have been displayed in this research.
$P$-extremal functions and Bernstein-Markov properties associated to compact sets in $\mathbb R^d$
Hoang Thieu Anh,Kieu Phuong Chi,Nguyen Quang Dieu,Tang Van Long 대한수학회 2022 대한수학회보 Vol.59 No.4
Given a compact subset $P \subset (\R^+)^d$ and a compact set $K$ in $\C^d$. We concern with the Bernstein-Markov properties of the triple $(P,K,\mu)$ where $\mu$ is a finite positive Borel measure with compact support $K$. Our approach uses (global) $P$-extremal functions which is inspired by the classical case (when $P=\Sigma$ the unit simplex) in \cite{BloomLe99}.