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Synthesis of TiO<sub>2</sub> Nanotubes and Their Sensitivity for Toluene Gas
Yue, H.Y.,Huang, S.,Guo, E.J.,Wang, L.P.,Kang, F.W.,Yu, Z.M.,Guo, Y.K.,Sun, F.L. The Korean Powder Metallurgy Institute 2011 한국분말재료학회지 (KPMI) Vol.18 No.1
$TiO_2$ nanopowders with anatase structure were firstly prepared by controlling the pH value of a precursor solution without any heat-treatment at room temperature. The prepared $TiO_2$ nanopowders were hydrothermally treated in 10M NaOH solution at $170^{\circ}C$. Then, the samples were washed in DI water or 0.1M HCl. The $TiO_2$ nanotubes were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). The gas sensitivity of $TiO_2$ nanotubes for toluene gas was also investigated. The results show that $TiO_2$ nanotubes can be prepared by hydrothermal treatment. The morphology of $TiO_2$ nanotubes prepared by 0.1M HCl washing is destroyed to some extent. $TiO_2$ nanotubes with DI water washing show better sensitivity than that with 0.1M HCl washing.
Y. Q. Li,M. Yue,J. H. Zuo,D. T. Zhang,W. Q. Liu,J. X. Zhang,Z. H. Guo,W. Li 한국자기학회 2013 Journal of Magnetics Vol.18 No.3
A finite element model was built for MnBi/α-Fe nanocomposite permanent magnets, and the demagnetization curves of the magnets were simulated by micro-magnetic calculation. The microstructure of the cubic model is composed of 64 irregular grains with an average grain size of 20 nm. With the volume fraction of soft magnetic phase (t vol. %) ranged from 5 to 20 vol. %, both isotropic and anisotropic nanocomposite magnets show typical single-phase permanent magnets behavior in their demagnetization curves, illustrating good intergranular exchange coupling effect between soft and hard magnetic phases. With the increase of volume fraction of soft magnetic phase in both isotropic and anisotropic magnets, the coercive force of the magnets decreases monotonically, while the remanence rises at first to a peak value, then decreases. The optimal values of maximum energy products of isotropic and anisotropic magnets are 84 and 200 kJ/m3, respectively. Our simulation shows that the MnBi/α-Fe nanocomposite permanent magnets own excellent magnetic properties and therefore good potential for practical applications.
C.H. Li,W. Zhao,J.L. Zhang,W. Lu,P. Li,B.J. Yan,H.W. Guo 한양대학교 세라믹연구소 2021 Journal of Ceramic Processing Research Vol.22 No.4
The bluestone tailings are quickly expanded in China with the continuous utilization and mining of bluestone resources. Theincremental recycling of bluestone tailings is important to solve the resources waste and environmental pollution. This studyaims to reuse the bluestone tailings as the main material to prepare α-cordierite glass-ceramics based on melting process. Theresults show that the nucleation temperature, crystallization peak temperature and the activation energy for crystallizationdecreased gradually with increasing the percentage of bluestone tailings. The complete preparation parameters of α-cordieriteglass-ceramics include a bluestone tailings percentage of 70%, a heating rate of 5 oC·min^-1, a crystallization duration of 1.5h, a crystallization temperature of 970 oC, a nucleation temperature of 830 oC, and a nucleation duration of 1.0 h. Theperformances analyses reveals that the α-cordierite glass-ceramics based on the optimized parameters exhibits high densityand Vickers hardness, low dielectric loss and water absorption, and strong chemical resistance.
Research of Seamless Transfer Control Strategy of Microgrid System
M.J. Yang,F. Zhuo,X.W. Wang,H.P. Guo,Y.J. Zhou 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5
Microgrid has two typical working modes: grid-connected mode and islanded mode. The transfer between these two modes should be seamless. In a microgrid that uses master-slave strategy to avoid circumfluence in the islanded mode, to control the master converter’s voltage is to control the microgrid voltage. Considering this, the master converter in this paper works as a voltage-controlled inverter when the microgrid is disconnecting from the utility grid while working as a current-controlled rectifier when the microgrid is in the grid-connected mode. Besides, by gradually adjusting the master converter’s output voltage to equal that of the utility grid when the microgrid is going to connect the utility grid and by setting an appropriate initial phase of the converter voltage when the microgrid needs to work alone, the seamless transfers between these two modes are accomplished. Experiment has been done to validate the accuracy, rapidity and reliability of this strategy.