中国科学院机构知识库网格系统: 检索

Experimental Study on the Effects of Discharge Chamber Length on 5 cm Radio-Frequency Ion Thruster 期刊论文 OAI收割
MICROGRAVITY SCIENCE AND TECHNOLOGY, 2020, 页码: 8
作者: Ma LF(马隆飞); He JW(贺建武); Duan L(段俐); Kang Q(康琦)

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收藏 | 浏览/下载：34/0 | 提交时间：2020/05/18

Microgravity condition Radio-frequency ion thruster Discharge chamber length Electron density

Three-Dimensional Aerators: Characteristics of the Air Bubbles 期刊论文 OAI收割
Water, 2018, 卷号: 10, 页码: 1430
作者: Shuai Li; Jianmin Zhang; Xiaoqing Chen; Jiangang Chen; Chen, Jiangang

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收藏 | 浏览/下载：35/0 | 提交时间：2018/12/01

Three-dimensional Aerator Air Concentration Air Bubble Frequency Air Bubble Chord Length

Effects of Conjugate Gradient Methods and Step-Length Formulas on the Multiscale Full Waveform Inversion in Time Domain: Numerical Experiments 期刊论文 OAI收割
PURE AND APPLIED GEOPHYSICS, 2017, 卷号: 174, 期号: 5, 页码: 1983-2006
作者: Liu, Youshan; Teng, Jiwen; Xu, Tao; Badal, Jos; Liu, Qinya

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收藏 | 浏览/下载：28/0 | 提交时间：2017/11/15

Full waveform inversion nonlinear conjugate gradient method step-length formulas multiscale strategy frequency-band selection strategy

Seasonal variation in abundance, diel vertical migration and body size of pelagic tunicate Salpa fusiformis in the Southern Yellow Sea CNKI期刊论文 OAI收割
2012
作者: Liu YQ(刘永芹); Sun S(孙松); Zhang GT(张光涛)

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收藏 | 浏览/下载：2/0 | 提交时间：2024/12/18

Salpa fusiformis swarm diel vertical migration length frequency Southern Yellow Sea

Study on ultra-light secondary baffle for coaxial two-mirror telescope (EI CONFERENCE) 会议论文 OAI收割
2012 9th IEEE International Conference on Mechatronics and Automation, ICMA 2012, August 5, 2012 - August 8, 2012, Chengdu, China
作者: Zhang L.; Zhang L.

收藏 | 浏览/下载：74/0 | 提交时间：2013/03/25

The coaxial two-mirror telescope consists of two mirrors facing each other. Classical two-mirror arrangements are Gregorian and Cassegrain. These systems are usually applied to space telescopes and often have optical baffles to prevent stray light from entering the focal plane. The optical baffles consist of concentric rings suspended between the secondary and the primary mirror. The secondary baffle for a large two-mirror optical system is designed and analyzed in this paper. According to mission of a telescope the structure should have high stiffness and high reliability and light weight. Compared with invar aluminum alloy and titanium alloy carbon fiber composite is currently the best material in terms of weight-to-strength ratio. It also has advantages of high temperature tolerance and low thermal expansion. So carbon fiber composite is chosen as material to meet requirements of the coaxial telescope. In this paper optimization method based on finite element analysis (FEA) is used for design the secondary baffle. Minimum weight of the baffle is chosen as an objective function. Thicknesses of former tube and vanes are chosen as variables. Analysis results show that the designed secondary baffle has maximum diameter of 180mm total length of 120mm and weighs 142g. And its fundamental frequency reaches 651Hz. Therefore the baffle has many advantages such as ultra-light weight high stiffness and dimensional stability etc. The optimization method and the baffle design can be helpful to other coaxial telescopes such as Cassegrain Gregorian and their subdivisions. 2012 IEEE.

Comparison and simulation of subpixel imaging modes for linear CCD (EI CONFERENCE) 会议论文 OAI收割
2012 3rd International Conference on Information Technology for Manufacturing Systems, ITMS 2012, September 8, 2012 - September 9, 2012, Qingdao, China
作者: Li Y.; He B.; Li Y.; Li Y.; Li Y.

收藏 | 浏览/下载：45/0 | 提交时间：2013/03/25

Subpixel technique of linear CCD is effective to enhance the spatial resolution without increasing the focal length of optics and reducing the pixel size. To compare image quality of two main subpixel imaging modes quincunx sampling and four-point sampling a method to quantitatively evaluate image quality of subpixel based on MTF was proposed. The MTF of quincunx and four-point sampling modes were derived. Analytical results shows that theoretical limiting resolution of quincunx sampling and four-point sampling is improved to 1.4 and 1.86 times respectively and MTF values at Nyquist frequency of two modes are increased by 0.1106 and 0.1679 respectively. MTFA in (0 0.5) of two subpixel imaging modes were calculated and results illustrates that four-point sampling offers much more improvement with image quality than quincunx sampling at the cost of double amount of data. A model for simulating subpixel imaging using Matlab was established and simulation results of spoke target verify the theoretical analysis. (2012) Trans Tech Publications Switzerland.

Seasonal variation in abundance, diel vertical migration and body size of pelagic tunicate Salpa fusiformis in the Southern Yellow Sea 期刊论文 OAI收割
CHINESE JOURNAL OF OCEANOLOGY AND LIMNOLOGY, 2012, 卷号: 30, 期号: 1, 页码: 92-104
作者: Liu Yongqin; Sun Song; Zhang Guangtao

收藏 | 浏览/下载：34/0 | 提交时间：2013/09/24

Salpa fusiformis swarm diel vertical migration length frequency Southern Yellow Sea

On the performance of the open-shell perturbation theory 期刊论文 OAI收割
SCIENCE CHINA-CHEMISTRY, 2011, 卷号: 54, 期号: 3, 页码: 446-453
作者: Chen FeiWu; Wei MeiJu; Liu WenJian

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收藏 | 浏览/下载：32/0 | 提交时间：2019/04/09

Open Shell Perturbation Theory Convergence Bond Length Harmonic Vibrational Frequency

Structural design for lightweight off-axis TMA space telescope (EI CONFERENCE) 会议论文 OAI收割
2011 2nd International Conference on Digital Manufacturing and Automation, ICDMA 2011, August 5, 2011 - August 7, 2011, Zhangjiajie, Hunan, China
作者: Li Z.; Li Z.

收藏 | 浏览/下载：45/0 | 提交时间：2013/03/25

A kind of small space telescope with 1m focal length was designed. By adopting finite element analysis technique the structure of the space telescope was analyzed. The analysis results indicate that the surface profile accuracy of the mirrors reach to RMS 8.0nm with the working circumstances 4C uniform temperature change and space micro-gravity the base frequency of the structure was 115 Hz. It shows that the designed structure has sufficiently high dynamic and static stiffness and thermal dimensional stabiLity. This space optical telescope is very suitable for little satellite application. 2011 IEEE.

Research on lightweight outer baffle for coaxial space camera (EI CONFERENCE) 会议论文 OAI收割
2011 International Conference on Electronic and Mechanical Engineering and Information Technology, EMEIT 2011, August 12, 2011 - August 14, 2011, Harbin, China
作者: Zhang L.; Zhang L.

收藏 | 浏览/下载：23/0 | 提交时间：2013/03/25

Stray light is non-imaging light that reach the optical system imaging plane. The non-imaging light can be received by detector if it is not effectively controlled and stray light which directly irradiates on the detector has great influence on the imaging quality. Stray light can be effectively inhibited if the outer baffle of space camera is designed optimally. Carbon fiber composite material is chosen as main material to meet requirements of a coaxial space optical system. The outer baffle should have advantages such as lightweight high stiffness and dimensional stability etc. Using optimization design tools the lightweight outer baffle is designed. And finite element method is used to check the structure. Development and test results show that the outer baffle with a diameter of 620mm and a total length of 1200mm only weighs 7.3kg. And the baffle's natural frequency reaches 88Hz and it can satisfy the requirements of the space camera. 2011 IEEE.