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XIAOYU LI,HUAMING YANG,LIANGJIE FU,TIANCHENG LIU 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2014 NANO Vol.9 No.4
Nickel oxide (NiO) nanoparticles were synthesized by calcination at 400?C to 700?C for 8 h of theprecursor obtained via mechanochemical reaction of Ni(NO 3 ) 2 ? 6 H 2 O with citric acid as a dis-persant. The nanoparticles were characterized by thermogravimetric-diferential scanningcalorimetry (TG-DSC), X-ray difraction (XRD) and transmission electron microscopy (TEM). The kinetics of diferent surfaces of the nanocrystals under nonisothermal conditions wasinvestigated. The activation energies for diferent lattice planes of NiO nanoparticles weredetermined using the Arrhenius equation, revealing their preferred orientation. The growth ofNiO obeyed the general theory that nanoparticles with the largest surface energy tend to form. XRD data reveal that the NiO nanoparticles possess preferred (111) or (200) orientations thatre°ect their complex activity. The nature of preferred growth orientation was found to benegative difusion activity among diferent lattice surfaces, which indicates that oxygen atomsdi®use from low oxygen concentration on the lattice surface to high concentration on the latticesurface.
Lei Wang,Wei Luo,Liangjie Weng,Yongbo Hu,Bing Li 대한전기학회 2018 Journal of Electrical Engineering & Technology Vol.13 No.5
In this paper, the fault line selection and location problems of single line-to-ground (SLG) fault in distribution network are addressed. Firstly, the adaptive filtering property for empirical mode decomposition is formulated. Then in view of the different characteristics showed by the intrinsic mode functions(IMF) under different fault inception angles obtained by empirical mode decomposition, the sign of peak value about the low-frequency IMF and the capacitance transient energy is chosen as the fault line selection criteria according to the different proportion occupied by the low-frequency components. Finally, the fault location is determined based upon the comparison result with adjacent fault passage indicators’ (FPI) waveform on the strength of the interaction between the distribution terminal unit(DTU) and the FPI. Moreover, the logic nodes regarding to fault line selection and location are newly expanded according to IEC61850, which also provides reference to acquaint the DTU or FPI’s function and monitoring. The simulation results validate the effectiveness of the proposed fault line selection and location methods.
Homogenized thermal properties of 3D composites with full uncertainty in the microstructure
Juan Ma,Peter Wriggers,Liangjie Li 국제구조공학회 2016 Structural Engineering and Mechanics, An Int'l Jou Vol.57 No.2
In this work, random homogenization analysis for the effective thermal properties of a three-dimensional composite material with unidirectional fibers is presented by combining the equivalent inclusion method with Random Factor Method (RFM). The randomness of the micro-structural morphology and constituent material properties as well as the correlation among these random parameters are completely accounted for, and stochastic effective thermal properties as thermal expansion coefficients as well as their correlation are then sought. Results from the RFM and the Monte-Carlo Method (MCM) are compared. The impact of randomness and correlation of the micro-structural parameters on the random homogenized results is revealed by two methods simultaneously, and some important conclusions are obtained.
Sairong Zhu,Yong Yin,Liangjie Bi,Zhiwei Chang,Che Xu,Fanbo Zeng,Ruibin Peng,Wen Zhou,Bin Wang,Hailong Li,Lin Meng 한국물리학회 2018 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.73 No.9
A method aimed at improving the beam-wave interaction eciency by changing the coupling slot configuration has been proposed in the study of extended interaction oscillators (EIOs). The disper- sion characteristics, coupling coecient and interaction impedance of the high-frequency structure based on different types of coupling slots have been investigated. Four types of coupled cavity structures with different layouts of the coupling slots have been compared to improve the beam- wave interaction eciency, so as to analyze the beam-wave interaction and practical applications. In order to determine the improvement of the coupling slot to a coupled cavity circuit in an EIO, we designed four nine-gap EIOs based on the coupled cavity structure with different coupling slot configurations. With different operating frequencies and voltages takes into consideration, beam voltages from 27 to 33 kV have been simulated to achieve the best beam-wave interaction eciency so that the EIOs are able to work in the 2 mode. The in uence of the Rb and the ds on the output power is also taken into consideration. The Rb is the radius of the electron beam, and the ds is the width of the coupling slot. The simulation results indicate that a single-slot-type EIO has the best beam-wave interaction eciency. Its maximum output power is 2.8 kW and the eciency is 18% when the operating voltage is 31 kV and electric current is 0.5 A. The output powers of these four EIOs that were designed for comparison are not less than 1.7 kW. The improved coupling-slot con- gurations enables the extended interaction oscillator to meet the different engineering requirements better.
Wang, Lei,Luo, Wei,Weng, Liangjie,Hu, Yongbo,Li, Bing The Korean Institute of Electrical Engineers 2018 Journal of Electrical Engineering & Technology Vol.13 No.5
In this paper, the fault line selection and location problems of single line-to-ground (SLG) fault in distribution network are addressed. Firstly, the adaptive filtering property for empirical mode decomposition is formulated. Then in view of the different characteristics showed by the intrinsic mode functions(IMF) under different fault inception angles obtained by empirical mode decomposition, the sign of peak value about the low-frequency IMF and the capacitance transient energy is chosen as the fault line selection criteria according to the different proportion occupied by the low-frequency components. Finally, the fault location is determined based upon the comparison result with adjacent fault passage indicators' (FPI) waveform on the strength of the interaction between the distribution terminal unit(DTU) and the FPI. Moreover, the logic nodes regarding to fault line selection and location are newly expanded according to IEC61850, which also provides reference to acquaint the DTU or FPI's function and monitoring. The simulation results validate the effectiveness of the proposed fault line selection and location methods.