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338 results on '"Liu, Chun-Guang"'

17. Time–Frequency Buffeting Responses of Transmission Lines Excited by Two-Dimensional Turbulent Wind: Closed-Form Solution.

Author

Du, Wen-Long, Fu, Xing, Li, Hong-Nan, Li, Gang, and Liu, Chun-Guang

Subjects
ELECTRIC lines, WIND pressure, DEAD loads (Mechanics), FINITE element method, NONLINEAR analysis
Abstract

Currently, the buffeting analysis for transmission lines (TLs) only involves the excitation of horizontal turbulence, while numerous investigations have proven that significant vertical turbulence exists in many wind fields. Additionally, overhead conductors generally exhibit nonlinear behavior, rendering the conventional multidimensional wind-excited model based on linear theories no longer applicable. To address these challenges and avoid relying on the extremely time-consuming nonlinear finite-element method, this paper proposes a closed-form solution (CFS) for predicting time-frequency buffeting responses of TLs excited by two-dimensional turbulent wind. First, the static response is determined through nonlinear static analysis. Then a two-dimensional influence line method, employed to evaluate the turbulent wind effect, is developed by decoupling the buffeting responses in two directions. Power spectral density functions for various responses are further derived, considering the cross-correlation between horizontal and vertical turbulence. Moreover, the impact of wind attack angle on various responses is revealed through parametric analyses. Finally, an amplification factor is introduced to modify the vertical wind effect on equivalent static wind load (ESWL), and the corresponding fitting formula is provided to facilitate the design. Numerical verification illustrates the high accuracy and efficiency of the CFS. Although the wind attack angle is time-varying, it is controlled by the mean wind. As it increases, the RMS of transverse and longitudinal reactions decrease, while the RMS of the vertical reaction increases. Neglecting vertical turbulence underestimates the horizontal ESWL, with the amplification factor exceeding 1.35 when a wind attack angle of 50° is considered. [ABSTRACT FROM AUTHOR]

Published
2023
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30. Preparation, Luminescence and Thermal Stability of Li+/La3+ Co-doped Single-phased BaSi2O5∶Eu2+ Green Emitting Phosphors for White LEDs

Author

姜荣云 Jiang Rong-yun, 祝汉成 Zhu Han-cheng, 徐长山 Xu Chang-shan, 黄晓松 Huang Xiao-song, 刘春光 Liu Chun-guang, 严端廷 Yan Duan-ting, 刘玉学 Liu Yu-xue, and 杨 健 Yang Jian

Subjects
Radiation, Materials science, business.industry, Phosphor, Condensed Matter Physics, Electronic, Optical and Magnetic Materials, law.invention, law, Optoelectronics, Thermal stability, business, Luminescence, Co doped, Light-emitting diode
Published
2020

39. Preparation and Optical Properties of Eu2+ Doped 12CaO·7Al2O3 Blue Emitting Conductive Phosphors

Author

张 猛 Zhang Meng, 刘春光 Liu Chun-guang, 刘玉学 Liu Yu-xue, 高 旭 Gao Xu, 杨 健 Yang Jian, 祝汉成 Zhu Han-cheng, 徐长山 Xu Chang-shan, and 严端廷 Yan Duan-ting

Subjects
12CaO.7Al2O3, Radiation, Materials science, business.industry, Doping, Blue emitting, Optoelectronics, Phosphor, Condensed Matter Physics, business, Electrical conductor, Electronic, Optical and Magnetic Materials
Published
2019

41. Study on the Large Power Shortage Island Self-healing Method of Smart Distribution Network Based on Status of Protection

Author

Xu Pei-dong, Cao Wei-jie, Zhou Xiao-qiang, Liu Chun-guang, Qiao Jin-xing, and Xu Rui

Subjects
Scheme (programming language), Computer science, Reliability (computer networking), Key (cryptography), Islanding, State (computer science), Investment (macroeconomics), computer, Unit (housing), computer.programming_language, Reliability engineering, Power (physics)
Abstract

A large number of distributed generators access to low-voltage distribution network, in case of failure disturbance, the system is easy to enter a low power quality instability islanding operation state. When the power capacity of the island is much smaller than the load demand(there is a high power shortage), it is the key to realize the island's automatic restoration to normal operation by improving the protection coordination scheme. The paper analyzes the shortcomings of the prior setting scheme for under-frequency load-shedding device and automatic switching device, especially when large power shortage happens in an unstable island network, and then proposed a zero increase investment method for island self-healing in smart distribution network. The proposed method aims to give priority to ensuring the safety of the unit, achieve the goal of optimal unit safety by improving the protection coordination scheme, and ensure the automatic grid-connected operation of the power supply with zero loss. By actual grid fault simulation analysis, it is proved that the proposed method improves the reliability of power supply and avoids unit into an unstable operating state. It has great engineering application value, and now has been applied in a certain city Power Grid of Jiangsu province.

Published
2020

44. Synergistic Effects of Keggin-Type Phosphotungstic Acid-Supported Single-Atom Catalysts in a Fast NH3-SCR Reaction

Author

Lin, Chun-Hong, Qin, Rui-Cheng, Cao, Ning, Wang, Dan, and Liu, Chun-Guang

Abstract

Fast selective catalytic reduction of nitrogen oxide with ammonia (NH3-SCR) (2NH3+ NO2+ NO → 2N2+ 3H2O) has aroused great interest in recent years because it is inherently faster than the standard NH3-SCR reaction (4NO + 4NH3+ O2→ 4N2+ 6H2O). In the present paper, the mechanism of the fast NH3-SCR reaction catalyzed by a series of single-atom catalysts (SACs), M1/PTA SACs (PTA = Keggin-type phosphotungstic acid, M = Mn, Fe, Co, Ni, Ru, Rh, Pd, Ir, and Pt), has been systematically studied by means of density functional theory (DFT) calculations. Molecular geometry and electronic structural analysis show that Jahn–Teller distortion effects promote an electron transfer process from N–H bonding orbitals of the NH3molecule to the symmetry-allowed d orbitals (dxyand dx2–y2) of the single metal atom, which effectively weakens the N–H bond of the adsorbed NH3molecule. The calculated free energy profiles along the favorable catalytic path show that decomposition of NH3to *NH2and *H species and decomposition of *NHNOH into N2and H2O have high free energy barriers in the whole fast NH3-SCR path. A good synergistic effect between the Brønsted acid site (surface oxygen atom in the PTA support) and the Lewis acid site (single metal atom) effectively enhances the decomposition of NH3to *NH2and *H species. M1/PTA SACs (M = Ru, Rh, Pd, and Pt) were found to have potential for fast NH3-SCR reaction because of the relatively small free energy barrier and strong thermodynamic driving forces. We hope our computational results could provide some new ideas for designing and fabricating fast NH3-SCR catalysts with high activity.

Published
2022
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47. Characterization and Storage Property of Dy3+ Doped C12A7 X-ray Phosphors with Yellowish-green Emission

Author

李胜男 Li Sheng-nan, 张 猛 Zhang Meng, 杨 健 Yang Jian, 严端廷 Yan Duan-ting, 侯 爽 Hou Shuang, 刘春光 Liu Chun-guang, 祝汉成 Zhu Han-cheng, 徐长山 Xu Chang-shan, and 刘玉学 Liu Yu-xue

Subjects
Radiation, Materials science, business.industry, Doping, X-ray, Optoelectronics, Phosphor, Condensed Matter Physics, business, Green emission, Electronic, Optical and Magnetic Materials, Characterization (materials science)
Published
2018

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