中国科学院机构知识库网格系统: 检索

A method to estimate the neutral atmospheric density near the ionospheric main peak of Mars 期刊论文 OAI收割
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, 2016, 卷号: 121, 期号: 4, 页码: 3464-3475
作者: Zou, Hong; Ye, Yu Guang; Wang, Jin Song; Nielsen, Erling; Cui, Jun

收藏 | 浏览/下载：29/0 | 提交时间：2016/10/27

The neutral densities at 130 km can be derived fromtheMGS/RS measurements with our method The derived neutral densities can be used to verify or calibrate the Martian atmospheric model The method can be applied to other radio occultation measurements such as MEX/RS measurements

Stray light analysis of solar photoelectric detection system on space target (EI CONFERENCE) 会议论文 OAI收割
2012 International Conference on Intelligent System and Applied Material, GSAM 2012, January 13, 2012 - January 15, 2012, Taiyuan, Shanxi, China
Li L.-Y.; Wang Y.-F.; San X.-G.

收藏 | 浏览/下载：148/0 | 提交时间：2013/03/25

Most conventional spacious solar photoelectric detection systems suffer from unexpected stray light. This paper demonstrates the effects on photoelectric detection system bring out by stray light. On this foundation build up evaluation index of stray light system to search the reasonable programme to eliminating stray light. A detailed telescope system geometry model was created and scatter models were create for telescope and enclosure components. By the means of designing the structure of main baffle baffle vane and the coating technology. In order to verify the prosperity of structure that designed we utilizes software to analysis opto-mechanical model. we utilizes software to analysis opto-mechanical model. The simulations show that point source transmittance of the system is thus reduced by up to two orders of magnitude between 10-8 and 10-10. Meanwhile the experiment obtains clean detection data which satisfies the system requirements. Stray light has been suppressed effectually and so measurement precision was improved from detection graphics. (2012) Trans Tech Publications.

Immersed nanospheres super-lithography for the fabrication of sub-70nm nanoholes with period below 700nm (EI CONFERENCE) 会议论文 OAI收割
2012 12th IEEE International Conference on Nanotechnology, NANO 2012, August 20, 2012 - August 23, 2012, Birmingham, United kingdom
作者: Li S.; Du J.; Shi L.

收藏 | 浏览/下载：144/0 | 提交时间：2013/03/25

A maskless nano-lithography method by using polystyrene spheres (PSs) self-assembled on silver slab (NSSL) was proposed in [optics express Vol. 16 No. 19 (2008) 14397]. Following that to break the limitations in resolution and PSs period of NSSL method in this paper we present PSs immersed super-resolution lithography (NSISL) technology by embedding the PSs into appropriate material to improve the efficiency of the surface plasmon excitation. The energy modulating mechanism and the rules of the resolution affected by silver slab were studied by calculating and analysing the energy distribution. The curve of the lithography resolution versus the silver thickness was presented. In order to verify this method contrast analysis was carried out with NSSL. The results show that the lithography resolution is improved efficiently. Taking a specific configuration with PS diameter of 600nm as an example the resolution was improved to 54nm from 190nm with Ag thickness of 25nm. Based on the calculation results we carried out the experiments. Nano holes with dimension of 75nm and period of 600nm were obtained. 2012 IEEE.

Design of semi-physical simulation for small satellite by virtual display (EI CONFERENCE) 会议论文 OAI收割
2011 3rd International Conference on Mechanical and Electronics Engineering, ICMEE 2011, September 23, 2011 - September 25, 2011, Hefei, China
Xu K.; Lv Y.; Jin G.

收藏 | 浏览/下载：23/0 | 提交时间：2013/03/25

Semi-physical simulation of attitude control system is the more synthetically test and verify for designing of small satellite control system. It is an important means of small satellite development. However the results of current semi-physical simulation system have a lot of non-intuitive. Compare with the actual environment the simulation environment still has striking disparity. So the shortcomings affect precision of simulation. Based on the virtual display technology the group semi-physical simulation system has been constructed for attitude control of small satellite due to the combination with xPC real-time environment the simulation computer high-precision single-axis air-bearing turntable reaction wheel air thrust device fiber gyroscopes sensors synchronizer power subsystem and wireless devices virtual display computer etc. Semi-physical simulation achieved the visual simulation in orbit and tracked new information of virtual environment of space into real-time simulation computer. Simulation results show that the simulation system for real-time attitude and orbit position of small satellite semi-physical simulation has an excellent display effect. At the same time Real-time transfuse of orbit information provides a more accurate space environment simulation. The simulation system of small satellite attitude control to design and evaluate the more direct and convenient. (2012) Trans Tech Publications Switzerland.

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：42/0 | 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.

Study of horizontal shafting with spherical four-way structure (EI CONFERENCE) 会议论文 OAI收割
2012 International Conference on Optoelectronics and Microelectronics, ICOM 2012, August 23, 2012 - August 25, 2012, Changchun, China
作者: Yang L.; Yang L.

收藏 | 浏览/下载：34/0 | 提交时间：2013/03/25

Altazimuth photoelectric theodolite level shaft U-type and T-type structure but with the expanding field of applications of photoelectric theodolite the horizontal shaft structure occur great changes. For example in the marine environment shipboard conditions the instrument has a waterproof corrosion-resistant easy maintenance and other functions while carrier-based optoelectronic devices from a single visible television configure the development of integrated infrared system and ranging system as one of the single-station measurement system due to the spherical structure has sufficient internal space exactly adapted to this need. In this paper the horizontal axis of a spherical four-way structure. From aspects of the spherical four-way split in the form and shafting design and finite element analysis of the detailed design. A spherical four-way horizontal axis system diameter 550mm weight 19kg sphere in the 40kg load the maximum deformation of 3.3m fully meet the requirements. The shaft of the structure of the shaking is less than 2 arc seconds the vibration test the re-examination instrument accuracy change is less than 1 arc seconds. Verify that the structure is stable and reliable. 2012 IEEE.

Tracking error modeling of the theodolite based on GRNN method (EI CONFERENCE) 会议论文 OAI收割
2nd International Conference on Frontiers of Manufacturing and Design Science, ICFMD 2011, December 11, 2011 - December 13, 2011, Taichung, Taiwan
作者: Li M.

收藏 | 浏览/下载：28/0 | 提交时间：2013/03/25

To meet the requirement of high tracking accuracy as well as develop more reasonable evaluation method in this paper the General Regression Neural Network (GRNN) has been applied to build the tracking error model of the theodolite. First we analyze the nonlinear factors in the theodolite. Second we discuss the principle of GRNN including its structure the function as well as its priors. Third we build the tracking error model based on GRNN and verify the model through the different parameters. The result indicated that the network model based on GRNN has high accuracy and good generalization ability. It could instead the real system to a certain extent. The research in this paper has important value to the engineering practice.

Experiments and finite element simulations on micro-milling of aluminium alloy7050-T7451 (EI CONFERENCE) 会议论文 OAI收割
10th Asia-Pacific Conference on Materials Processing, APCMP 2012, June 14, 2012 - June 17, 2012, Jinan, China
作者: Li J.; Li J.; Li J.; Zhou J.; Wang F.

收藏 | 浏览/下载：38/0 | 提交时间：2013/03/25

The mechanism of micro-milling modeling for aluminum alloy 7050-T745 is to be investigated and a finite element model for micro-milling that reflects the actual state of the three-dimensional micro-milling is built by adopting the software of ABAQUS/Explicit. Experiment is conducted to verify the validation of the model. Simulated chip morphology in different cutting parameters agrees to the experimental results very well. Based on the FE model cutting stresses equivalent plastic strains temperatures distribution and cutting forces are obtained and analyzed. This provides a good method to investigate the micro milling principles. (2012) Trans Tech Publications.

Three-dimensional transient numerical simulation of gaussian laser beam drilling process 会议论文 OAI收割
23rd International Congress of Theoretical and Applied Mechanics, 中国北京/Beijing, China, 2012-08-19
作者: Ge ZF(葛志福); Yu G(虞钢); He XL(何秀丽); Lu GQ; Li SX(李少霞)

收藏 | 浏览/下载：24/0 | 提交时间：2014/03/19

drilling simulation laser dimensional transient numerical process diameter Profile defocus different Gaussian three boiling negative material highly validity ejection verify

Space camera dynamic image quality measurement and evaluation (EI CONFERENCE) 会议论文 OAI收割
3rd International Conference on Measuring Technology and Mechatronics Automation, ICMTMA 2011, January 6, 2011 - January 7, 2011, Shanghai, China
作者: Zhang X.; Zhang X.; Zhang X.

收藏 | 浏览/下载：28/0 | 提交时间：2013/03/25

By using analysis of the infinity image of the space camera we intend to obtain the curve of the dynamic modulation transfer function. We extract the pixel gray values at the image edge which distribute as a knife-edge function and make differential calculation and Fourier transformation of it and then we can obtain the dynamic MTF curve of the optical system. The value of the curve at the Nyquist frequency is the most important parameter that reflects the image quality. We add push-scanning imaging and environmental effects to the static MTF of space camera and compare the MTF value with the dynamic MTF at Nyquist frequency. The comparison result can help us verify the accuracy of the calculating results and the feasibility of our method. (2011) Trans Tech Publications.