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RISS 인기검색어
- 검색키워드
- 저자 : You-He Zhou (검색결과 12 건)
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He, Feng-You,Xu, Shi-Zhou,Geng, Cheng-Fei The Korean Institute of Power Electronics 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.6
Laminated busbars with a low stray inductance are widely used in NPC three-level inverters, even though some of them have poor performances in heat equilibrium and overvoltage suppression. Therefore, a theoretical method is in need to establish an accurate mathematical model of laminated busbars and to calculate the impedance and stray inductance of each commutation loop to improve the heat equilibrium and overvoltage suppression performance. Firstly, an equivalent circuit of a NPC three-level inverter laminated busbar was built with an analysis of the commutation processes. Secondly, on the basis of a 3D (three dimensional) cubical thermal model and mirror circulation theory, a supersymmetric mirror circulation 3D cubical thermal model was built. Based on this, the laminated busbar was decomposed in 3D space to calculate the equivalent resistance and stray inductance in each commutation loop. Finally, the model and analysis results were put into a busbar design, simulation and experiments, whose results demonstrate the accuracy and feasibility of the proposed method.
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Lei Zhou,Tanghong Liu,Zhengwei Chen,Wenhui Li,Zijian Guo,Xuhui He,You-Wu Wang 한국풍공학회 2021 Wind and Structures, An International Journal (WAS Vol.32 No.6
This paper studied the case of high-speed train running from flat ground to bridges and into/out of tunnels, with or without crosswind based on the Computational Fluid Dynamics (CFD) method. First, the flow structure was analyzed to explain the influence mechanisms of different infrastructures on the aerodynamic characteristics of the train. Then, the evolution of aerodynamic forces of the train during the entire process was analyzed and compared. Additionally, the pressure variation on the train body and the tunnel wall was examined in detail. The results showed that the pressure coefficient and the flow structure on both sides of the high-speed train were symmetrical for no crosswind case. By contrast, under crosswind, there was a tremendous and immediate change in the pressure mapping and flow structure when the train passing through the bridge-tunnel section. The influence of the ground-bridge transition on the aerodynamic forces was much smaller than that of the bridge-tunnel section. Moreover, the variation of aerodynamic load during the process of entering and exiting the bridge-tunnel sections was both significant. In addition, in the case without crosswind, the change in the pressure change in the tunnel conformed to the law of pressure wave propagation, while under crosswind, the variation in pressure was comprehensively affected by both the train and crosswind in the tunnel.
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Feng-You He,Shi-Zhou Xu,Cheng-Fei Geng 전력전자학회 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.6
Laminated busbars with a low stray inductance are widely used in NPC three-level inverters, even though some of them have poor performances in heat equilibrium and overvoltage suppression. Therefore, a theoretical method is in need to establish an accurate mathematical model of laminated busbars and to calculate the impedance and stray inductance of each commutation loop to improve the heat equilibrium and overvoltage suppression performance. Firstly, an equivalent circuit of a NPC three-level inverter laminated busbar was built with an analysis of the commutation processes. Secondly, on the basis of a 3D (three dimensional) cubical thermal model and mirror circulation theory, a supersymmetric mirror circulation 3D cubical thermal model was built. Based on this, the laminated busbar was decomposed in 3D space to calculate the equivalent resistance and stray inductance in each commutation loop. Finally, the model and analysis results were put into a busbar design, simulation and experiments, whose results demonstrate the accuracy and feasibility of the proposed method.
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Shi-Zhou Xu,Feng-You He 전력전자학회 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.4
In some special occasions with strict size requirements, such as mine hoists, improving the design accuracy of the forced-air cooling systems of NPC three-level inverters is a key technology for improving the power density and decreasing the volume. First, a fast power-loss calculation method was brought. Its calculation principle introduced in detail, and the computation formulas were deduced. Secondly, the average and dynamic power losses of a 1MW mine hoist acting as the research target were analyzed, and a forced-air cooling system model based on a series of theoretical analyses was designed with the average power loss as a heat source. The simulation analyses proves the accuracy and effectiveness of this cooling system during the unit lifting period. Finally, according to an analysis of the periodic working condition, the maximum power-loss range of a NPC three-level inverter under multi cycle operation was obtained and its dynamic power loss was taken into the optimized cooling system model as a heat source to solve the power device damage caused by instantaneous heat accumulation. The effectiveness and feasibility of the optimization design based on the dynamic power loss calculation of the maximum power-loss range was proved by simulation and experimental results.
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Photocatalytic removal of methyl orange in an aqueous solution by a WO3/TiO2 composite film
Jian He,Qi Zhou Cai,Qiang Luo,Dan Qing Zhang,Teng Teng Tang,You Fang Jiang 한국화학공학회 2010 Korean Journal of Chemical Engineering Vol.27 No.2
WO3/TiO2 composite film was prepared by microarc oxidation technique and characterized by SEM, XRD,UV-vis spectra and Zeta-potential. The photocatalytic activity of WO3/TiO2 composite film was evaluated by examining the degradation of methyl orange. The influence of solution pH and inorganic anions on removal ratio of methyl orange was investigated. Removal ratio of methyl orange decreased with an increase of pH value in acidic solution, while it increased with the pH value in alkaline solution. The influence of added anions on the removal ratio is divided into two aspects. Addition of Cl− and SO42− resulted in a decrease in photocatalytic removal ratio of methyl orange, while it was facilitated by PO43−, HCO3− and NO3−.
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Xu, Shi-Zhou,He, Feng-You The Korean Institute of Power Electronics 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.4
In some special occasions with strict size requirements, such as mine hoists, improving the design accuracy of the forced-air cooling systems of NPC three-level inverters is a key technology for improving the power density and decreasing the volume. First, a fast power-loss calculation method was brought. Its calculation principle introduced in detail, and the computation formulas were deduced. Secondly, the average and dynamic power losses of a 1MW mine hoist acting as the research target were analyzed, and a forced-air cooling system model based on a series of theoretical analyses was designed with the average power loss as a heat source. The simulation analyses proves the accuracy and effectiveness of this cooling system during the unit lifting period. Finally, according to an analysis of the periodic working condition, the maximum power-loss range of a NPC three-level inverter under multi cycle operation was obtained and its dynamic power loss was taken into the optimized cooling system model as a heat source to solve the power device damage caused by instantaneous heat accumulation. The effectiveness and feasibility of the optimization design based on the dynamic power loss calculation of the maximum power-loss range was proved by simulation and experimental results.
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RhoGDI2 induced malignant phenotypes of pancreatic cancer cells via regulating Snail expression
Yi Bin,Hu You,Zhu Dongming,Yao Jun,Zhou Jian,Zhang Yi,He Zhilong,Zhang Lifeng,Zhang Zixiang,Yang Jian,Tang Yuchen,Huang Yujie,Li Dechun,Liu Qiuhua 한국유전학회 2022 Genes & Genomics Vol.44 No.5
Background: Rho GDP dissociation inhibitor 2 (RhoGDI2) has been shown to contribute to the aggressive phenotypes of human cancers, such as tumor metastasis and chemoresistance. Objective: This study aimed to assess the effects of RhoGDI2 on tumor progression and chemoresistance in pancreatic cancer cells. Methods: The expression of RhoGDI2 in pancreatic cancer cells was detected by Western blot analysis. Gain-of-function and loss-of-function approaches were done to examine the malignant phenotypes of the RhoGDI2-expressing or RhoGDI2-depleting cells. The correlation between RhoGDI2 and Snail was also analyzed. Results: Differential expression of RhoGDI2 protein in pancreatic cancer cell lines was identified. Gain-of-function and loss-of-function experiments showed that RhoGDI2 induced the malignant phenotypes of pancreatic cancer cells, including proliferation, migration, invasion, and gemcitabine (GEM) chemoresistance. The upregulation of RhoGDI2 stimulated the expression of Snail, resulting in the altered expression of epithelial marker E-cadherin and mesenchymal marker Vimentin, which were characteristics of the tumorigenic activity of epithelial-mesenchymal transition. The expression of RhoGDI2 and Snail was upregulated in clinical tumor samples, and higher expression of RhoGDI2 or Snail was significantly associated with poor patient survival in pancreatic ductal adenocarcinoma (PDAC). Conclusion: The findings indicated that RhoGDI2 promoted GEM resistance and tumor progression in pancreatic cancer and that RhoGDI2 might be a potential therapeutic target in patients with PDAC.
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A New Algorithm for Non-Rigid Shape Matching with Anisotropic-Scaling Transformation Parameters
Wen-Long Li,He Xie,Zhou-Ping Yin,You-Lun Xiong 한국정밀공학회 2015 International Journal of Precision Engineering and Vol. No.
Three-dimensional (3D) shape matching finds a wide application in manufacturing industry, such as surface inspection, workpiece localization and reverse engineering. In this paper, a new optimization method is proposed for non-rigid shape matching modeling and solving. The point-tangent distance function is used to construct a nonlinear least-squares model for anisotropic non-rigid shape matching, from which 9 variables with respect to non-rigid matching parameters are computed simultaneously by solving a linear system. In order to strengthen the non-rigid matching robustness to potential outliers, the optimization model is improved by an iteratively reweighted method. The typical characteristic is to weaken the influence of outliers during iterations. Finally, experiments are carried out to evaluate and analyze the proposed method, including matching accuracy, efficiency and robustness. Shape matching is also an important task in computer vision (such as face registration and object recognition), and the proposed method can find its application in this field.
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Zhi-Wen Gao,이강용,You-He Zhou 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.2
In this letter, the shielding or anti-shielding effect is firstly applied to obtain the behavior of two parallel cracks in a two-dimensional type-II superconducting under electromagnetic force. Fracture analysis is performed by the finite element method and the magnetic behavior of superconductor is described by the critical state Bean model. The stress intensity factors at the crack tips can be obtained and discussed for decreasing field after zero-field cooling. The shielding or anti-shielding effect at the crack tips depend on the distance between two parallel cracks and the crack length. The results indicate that the shielding effects of the two parallel cracks increase when the distance between the two parallel cracks decreases. It can be also obtained that the superconductors with shorter cracks has more remarkable shielding effect than those with longer cracks.
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Kouzhong Shi,Jun Li,San He,Han Bai,Yang Hong,You Wu,Dechang Jia,Zhongxiang Zhou 한국물리학회 2019 Current Applied Physics Vol.19 No.7
Large reflection loss and wide bandwidth are significant targets, determining the microwave absorption ability. However, it is still a challenge to simultaneously satisfy the two conditions. As a multifunctional material, BaFe12O19 possess excellent electromagnetic properties in the microwave frequency band. Due to the natural resonance phenomenon of the material, BaFe12O19 can produce a large magnetic loss which correlates with Fe3+ content, and the microwave absorption characteristics of barium ferrite can be modulated by ion doping. As a typical magnetic metal, Ni coupled with high-valence state Zr4+ doping helps to produce double resonance peaks. In this work, Ni2+-Zr4+ co-doping M-type barium ferrites (BaFe12-2xNixZrxO19, BNZFO-x, x=0–0.8) were prepared conveniently by solid-state reaction method. Several necessary measurements to characterize its microwave absorption property have been operated such as morphology, magnetic performance and electromagnetic parameters. The results show that reflection loss and bandwidth can be simply tuned by tailoring Ni2+- Zr4+ content. The reflection loss peak drifts from 18 GHz to 9.76 GHz, which involves a half of the studied frequency range. The maximum reflection loss achieves −60.6 dB and the corresponding bandwidth over −10 dB is 7.68 GHz for BNZFO-0.6 ceramic with only 2.1mm thickness. Thus, the doping of Ni2+-Zr4+ ion pairs is beneficial to improve the absorbing properties of the material, and the superior microwave absorption property may originate from its inner double natural resonance in micro-scale. The excellent microwave absorption properties suggest that BNZFO-x is a promising candidate applied for designing electromagnetic shielding devices.
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