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Impacts of air pressure on the evolution of nanosecond pulse discharge products

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Chinese Physics B 2013年第5期22卷 363-368页

作者：于锦禄何立明丁未王育虔杜纯 The Engineering Institute Air Force Engineering University Department of Training Air Force Engineering University

Based on the nonequilibrium plasma dynamics of air discharge, a dynamic model of zero-dimensional plasma is established by combining the component density equation, the Boltzmann equation, and the energy transfer equation. The evolution properties of nanosecond pulse discharge （NPD） plasma under different air pressures are calculated. The results show that the air pressure has significant impacts on the NPD products and the peak values of particle number density for particles such as O atoms, 03 molecules, N2（A3） molecules in excited states, and NO molecules. It increases at first and then decreases with the increase of air pressure. On the other hand, the peak values of particle number density for N2（B3） and N2（C3） molecules in excited states are only slightly affected by the air pressure.

关键词： plasma air pressure evolution numerical simulation

Preparation,characterization and catalytic oxidation property of CeO_2/Cu^(2+)-attapulgite (ATP) nanocomposites

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Journal of Rare Earths 2010年第S1期28卷 347-352页

作者：游静陈丰赵晓兵陈志刚 School of Information Science and Engineering Changzhou University School of Materials Science and Engineering Changzhou University

Cerium oxide(CeO2) coated on copper modified attapulgite clay nanocomoposite(CeO2/Cu2+-ATP) was prepared by homogeneous deposition *** microstructures of the as-prepared CeO2/Cu2+-ATP nanocomposites were characterized by X-ray diffraction(XRD),energy-dispersive spectrometer(EDS) and transmission electron microscopy(TEM).The results indicated that CeO2 particles with average size of about 5 nm were loaded onto the Cu2+-ATP and were widely *** the catalytic activity of ATP/CeO2 and CeO2/Cu2+-ATP,the catalytic activity was improved when a small quantity of Cu2+ was *** loading amount of CeO2 and reaction temperature had important effects on decolorization ratio of methyl orange(MO).When the loading amount and reaction temperature were 70% and 338 K,respectively,the decolorization ratio of MO reached over 99%,which showed excellent catalytic activity.

关键词： attapulgite cerium dioxide methyl orange catalytic activity rare earths

Sintering process as relevant parameter for Bi_2O_3 vaporization from ZnO-Bi_2O_3-based varistor ceramics

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中国有色金属学会会刊：英文版 2009年第6期19卷 1526-1532页

作者：徐东程晓农严学华徐红星施利毅 School of Materials Science and Engineering Jiangsu University School of Materials Science and Engineering Shanghai University

The relationship between sintering process and vaporization of the Bi2O3 in ZnO-Bi2O3-based varistor ceramics was *** phase and microstructure evolution during the sintering process were *** results show that the higher the sintering temperature or the longer the sintering time is,the more the Bi2O3 is *** heating rate has little effects on the Bi2O3 volatilized in ZnO-Bi2O3-based varistor *** is in accordance with the relative X-ray diffraction peak area ratio *** results also show that the sintering temperature has the greatest impact on the vaporization of the Bi2O3,then followed by sintering time,and the effect of the heating rate is the minimum.

关键词：烧结过程压敏陶瓷氧化锌铋基汽化微观组织演变烧结温度烧结时间

Development of an autonomous flapping-wing aerial vehicle

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Science China(Information Sciences) 2017年第6期60卷 249-256页

作者： Wei HE Haifeng HUANG Yunan CHEN Wenzhen XIE Fusen FENG Yemeng KANG Changyin SUN School of Automation and Electrical Engineering University of Science and Technology Beijing School of Automation Southeast University

The flapping-wing aerial vehicle(FWAV) has appealed to more and more researchers recently owing to its outstanding performance in various domains and the development of some related technologies. The research on autonomous flight control of the FWAV involves many challenges and is still in nascent stages. In this work, we develop an FWAV with a mass of 14.1 g and build a vision-based experimental platform. A modelbased controller is proposed on the basis of theory and simulation results prove its effectiveness. A PID control algorithm based on visual measurement is utilized to achieve the height-keeping control of the FWAV, and a software platform is designed to record the flight status determined using Euler angles and position information.

关键词： flapping-wing aerial vehicle autonomous robot control design vision-based control unmanned aerial vehicle

Numerical simulation of chemical vapor deposition reaction in polysilicon reduction furnace

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Journal of Central South university 2016年第1期23卷 44-51页

作者：夏小霞王志奇刘斌 Institute of Mechanical Engineering Xiangtan University School of Energy Science and Engineering Central South University

Three-dimensional model of chemical vapor deposition reaction in polysilicon reduction furnace was established by considering mass, momentum and energy transfer simultaneously. Then, CFD software was used to simulate the flow, heat transfer and chemical reaction process in reduction furnace and to analyze the change law of deposition characteristic along with the H_2 mole fraction, silicon rod height and silicon rod diameter. The results show that with the increase of H_2 mole fraction, silicon growth rate increases firstly and then decreases. On the contrary, SiHCl_3 conversion rate and unit energy consumption decrease firstly and then increase. Silicon production rate increases constantly. The optimal H_2 mole fraction is 0.8-0.85. With the growth of silicon rod height, Si HCl3 conversion rate, silicon production rate and silicon growth rate increase, while unit energy consumption decreases. In terms of chemical reaction, the higher the silicon rod is, the better the performance is. In the view of the top-heavy situation, the actual silicon rod height is limited to be below 3 m. With the increase of silicon rod diameter, silicon growth rate decreases firstly and then increases. Besides, SiHCl_3 conversion rate and silicon production rate increase, while unit energy consumption first decreases sharply, then becomes steady. In practice, the bigger silicon rod diameter is more suitable. The optimal silicon rod diameter must be over 120 mm.

关键词： polysilicon reduction furnace chemical vapor deposition silicon growth rate

Text Semantics Based Automatic Summarization for Chinese Videos

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Chinese Journal of Electronics 2015年第3期24卷 462-467页

作者： WANG Xingqi ZHA Taotao WU Chunming FANG Jinglong JIANG Ming School of Computer Science Hangzhou Dianzi University College of Computer Science and Technology Zhejiang University

This paper is concerned with the task of automatically summarizing videos, which is important for many video-related applications. Examples include video retrieval, accessing and categorization, et al. Our approach summarizes video semantically from the texts embedded in videos. To improve the accuracy, ant colony algorithm,maximum matching method, Singular value decomposition(SVD) are employed for locating text region, segmenting words and clustering sentences, respectively. Based on these methods, a prototype is developed. In an experimental evaluation on the real world video datasets, we show that our proposed approach could provide accurate, satisfactory performance.

关键词： Video summarization Ant colony algorithm Maximum matching method Singular value decomposition(SVD)

Waring-Goldbach Problem: One Square and Nine Biquadrates

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Chinese Annals of Mathematics,Series B 2019年第2期40卷 273-284页

作者： Xiaodong Lü Yingchun CAI School of Mathematical Science Yangzhou University Department of Mathematics Tongji University

In this paper it is proved that every sufficiently large even integer N satisfying one of the congruence conditions N ≡ 10, 58, 130, or 178(mod 240) may be represented as the sum of one square and nine fourth powers ... 详细信息

关键词： Waring-Goldbach problem Hardy-Littlewood method

On the limitations of linear beams for the problems of moving mass-beam interaction using a meshfree method

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Acta Mechanica Sinica 2012年第1期28卷 164-179页

作者： Keivan Kiani Ali Nikkhoo Department of Civil Engineering Islamic Azad University Department of Civil Engineering University of Science and Culture

This paper deals with the capabilities of linear and nonlinear beam theories in predicting the dynamic response of an elastically supported thin beam traversed by a moving mass. To this end, the discrete equations of motion are developed based on Lagrange＇s equations via reproducing kernel particle method （RKPM）. For a particular case of a simply supported beam, Galerkin method is also employed to verify the results obtained by RKPM, and a reasonably good agreement is achieved. Variations of the maximum dynamic deflection and bending moment associated with the linear and nonlinear beam theories are investigated in terms of moving mass weight and velocity for various beam boundary conditions. It is demonstrated that for majority of the moving mass velocities, the differences between the results of linear and nonlinear analyses become remarkable as the moving mass weight increases, particularly for high levels of moving mass velocity. Except for the cantilever beam, the nonlinear beam theory predicts higher possibility of moving mass separation from the base beam compared to the linear one. Furthermore, the accuracy levels of the linear beam theory are determined for thin beams under large deflections and small rotations as a function of moving mass weight and velocity in various boundary conditions.

关键词： Nonlinear beam theory Moving mass-beam in- teraction Euler-Bernoulli beam theory - Reproducing kernel particle method (RKPM) Galerkin method (GM)

Impingement capability of high-pressure submerged water jet: Numerical prediction and experimental verification

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Journal of Central South university 2015年第10期22卷 3712-3721页

作者：刘海霞邵启明康灿龚辰 School of Material Science and Engineering Jiangsu university School of Energy and Power Engineering Jiangsu university

At jet pressures ranging from 80 to 120 MPa, submerged water jets are investigated by numerical simulation and experiment. Numerical simulation enables a systematic analysis of major flow parameters such as jet velocity, turbulent kinetic energy as well as void fraction of cavitation. Experiments facilitate an objective assessment of surface morphology, micro hardness and surface roughness of the impinged samples. A comparison is implemented between submerged and non-submerged water jets. The results show that submerged water jet is characterized by low velocity magnitudes relative to non-submerged water jet at the same jet pressure. Shear effect serves as a key factor underlying the inception of cavitation in submerged water jet stream. Predicted annular shape of cavity zone is substantiated by local height distributions associated with experimentally obtained footprints. As jet pressure increases, joint contribution of jet kinetic energy and cavitation is demonstrated. While for non-submerged water jet, impingement force stems exclusively from flow velocity.

关键词： submerged water jet cavitation shear effect impingement test micro hardness surface morphology