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InSAR Image Registration Using Modified Correlation Coefficient Algorithm

2007 Asian and Pacific Conference on Synthetic Aperture Radar(APSAR 2007)

作者： Wenshuai Zhai yunhua zhang center for space science and applied research Chinese Academy of sciences Beijing 100080

Spatially Variant Apodization （SVA） is one of nonlinear apodization methods used for sidelobe control in SAR/ISAR or optical imagery while maintaining mainlobe resolution unchanged. In this paper,we apply SVA to process RADARSAT image and show that by using SVA one can get better resolution compared with using classic windowing techniques such as Hamming,etc. Also,we investigate the impact of SVA for phase sensitive applications and find that SVA can be used to enhance coherence of image pair for INSAR. SIR-C/X X-band experimental data are processed to demonstrate the significant effect of SVA.

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InSAR Image Registration Using Modified Correlation Coeffici...

2006 7th International Symposium on Antennas, Propagation and EM Theory

作者： Xiaojin Shi, yunhua zhang, and Jingshan Jiang center for space science and applied research, Chinese Academy of sciences P.O.Box 8701, Beijing 100080, China Graduate School of the Chinese Academy of sciences, Beijing 100039, China

In this paper, a modified correlation coefficient algorithm is proposed to accomplish image-registration for repeat-pass SAR interferometry. This algorithm utilizes a new definition of correlation coefficient to improve the calculation accuracy of offset between two images. Our simulation shows that Doppler centroid has a significant influence on the correlation coefficient and it should be removed before registration. SIR-C/X X-band experimental data has been processed to demonstrate the effect of the proposed algorithm. Also quantitative comparison between this paper's results and the results from the maximum-spectrum method is presented to show the improvement.

关键词： InSAR Image Registration Using Modified Correlation Coefficient Algorithm image Doppler

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线天线及天线阵的时域传输线矩阵法分析

微波学报 1996年第4期12卷 276-280,295页

作者：张云华陈抗生中国科学院空间科学与应用研究中心北京100080 浙江大学信电系杭州310027

本文针对线天线及天线阵的频域分析方法的缺点.首次将时域传输线矩阵(TLM)法应用到这一领域.应用时域TLM法时.只需经过一次运算就可以得到天线及天线阵的各个区域(近区.中间区和远区)的场特性.本文计算方法及数值结果表明,运用时域TLM... 详细信息

本文针对线天线及天线阵的频域分析方法的缺点.首次将时域传输线矩阵(TLM)法应用到这一领域.应用时域TLM法时.只需经过一次运算就可以得到天线及天线阵的各个区域(近区.中间区和远区)的场特性.本文计算方法及数值结果表明,运用时域TLM法可以对各种大型天线阵进行有效的分析,便于工程应用.

关键词：线天线天线阵雷达天线时域传输线矩阵法分析

Modified filter for mean elements estimation with state jumping

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Journal of Systems Engineering and Electronics 2024年第4期35卷 999-1012页

作者： YU Yanjun YUE Chengfei LI Huayi WU yunhua CHEN Xueqin research center of Satellite Technology Harbin Institute of TechnologyHarbin 150001China Institute of space science and applied Technology Harbin Institute of Technology(Shenzhen)Shenzhen 518055China College of Astronautics Nanjing University of Aeronautics and AstronauticsNanjing 211106China

To investigate the real-time mean orbital elements(MOEs)estimation problem under the influence of state jumping caused by non-fatal spacecraft collision or protective orbit trans-fer,a modified augmented square-root unscented Kalman filter(MASUKF)is *** MASUKF is composed of sigma points calculation,time update,modified state jumping detec-tion,and measurement *** with the filters used in the existing literature on MOEs estimation,it has three main ***,the state vector is augmented from six to nine by the added thrust acceleration terms,which makes the fil-ter additionally give the state-jumping-thrust-acceleration ***,the normalized innovation is used for state jumping detection to set detection threshold concisely and make the filter detect various state jumping with low ***,when sate jumping is detected,the covariance matrix inflation will be done,and then an extra time update process will be con-ducted at this time instance before measurement *** this way,the relatively large estimation error at the detection moment can significantly ***,typical simulations are per-formed to illustrated the effectiveness of the method.

关键词： unscented Kalman filter mean orbital elements(MOEs)estimation state jumping detection nonlinear system

Lunar ~3He estimations and related parameters analyses

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science China Earth sciences 2010年第8期53卷 1103-1114页

作者： LI DiHui, LIU HeGuang, zhang WeiGuo, LI Yun & XU ChuanDong center for space science and applied research, Chinese Academy of sciences, Beijing 100190, China center for space science and applied research Chinese Academy of Sciences Beijing China

As a potential nuclear fuel, 3He element is significant for both the solution of impending human energy crisis and the conservation of natural environment. Lunar regolith contains abundant and easily extracted 3He. Based on the analyses of the impact factors of 3He abundance, here we have compared a few key assessment parameters and approaches used in lunar regolith 3He reserve estimation and some representative estimation results, and discussed the issues concerned in 3He abundance variation and 3He reserve estimation. Our studies suggest that in a range of at least meters deep, 3He abundance in lunar regolith is homogeneously distributed and generally does not depend on the depth; lunar regolith has long been in a saturation state of 3He trapped by minerals through chemical bonds, and the temperature fluctuation on the lunar surface exerts little influence on the lattice 3He abundance. In terms of above conclusions and the newest lunar regolith depth data from the microwave brightness temperature retrieval of the "ChangE-1" Lunar Microwave Sounder, a new 3He reserve estimation has been presented.

关键词： lunar regolith 3He abundance reserve estimation maturity granularity composition solar wind flux CELMS

Correlative ionospheric disturbances in the sunlit hemisphere during the flare on July 14,2000

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Chinese science Bulletin 2002年第12期47卷 975-977页

作者： zhang Donghe & XIAO ZuoDepartment of Geophysics, Peking University, Beijing 100871, China Qingdao research center, Chinese research Institute of Radio-wave Propagation, Qingdao 266071, China center for space science and applied research, Chinese Academy o Department of Geophysics Peking University Beijing China Qingdao research center Chinese Research Institute of Radio-wave Propagation Qingdao China center for space science and applied research Chinese Academy of Sciences Beijing China

Using GPS data obtained from GPS sites located on the sunlit hemisphere during the flare on July 14, 2000, the ionospheric response to the flare was analyzed. A kind of tiny correlative ionospheric fluctuations were revealed from the temporal total electron content (TEC) curves derived from GPS measurements, and the values of this kind of disturbances are about 1015 m-2. A comparative analysis of these disturbances and soft X-ray flux detected at GOES satellite during the flare is done. It is found that this kind of disturbances revealed in the temporal TEC curves did occur in a very large area of sunlit ionosphere and its behavior is mainly controlled by the characteristics of the flare’s extra radiation. Because the similar fluctuations are not found in the curve of soft X-ray flux, it is concluded that the flare extra radiation in EUV band should have corresponding fluctuations and it is the fluctuations that cause the TEC disturbances. The height, where the disturbances occur, should be in the F

关键词： GPS TEC flare correlative disturbance.

Faster structured illumination microscopy using complementary encoding-based compressive imaging

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Photonics research 2024年第4期12卷 740-748页

作者： ZHENGQI HUANG yunhua YAO YILIN HE YU HE CHENGZHI JIN MENGDI GUO DALONG QI LIANZHONG DENG ZHENRONG SUN ZHIYONG WANG SHIAN zhang State Key Laboratory of Precision Spectroscopy School of Physics and Electronic ScienceEast China Normal UniversityShanghai 200241China School of Mathematical sciences University of Electronic Science and Technology of ChinaChengdu 611731China Joint research center of Light Manipulation science and Photonic Integrated Chip of East China Normal University and Shandong Normal University East China Normal UniversityShanghai 200241China Collaborative Innovation center of Extreme Optics Shanxi UniversityTaiyuan 030006China

Structured illumination microscopy (SIM) has been widely applied to investigate intricate biological dynamics due to its outstanding super-resolution imaging speed. Incorporating compressive sensing into SIM brings the possibility to further improve the super-resolution imaging speed. Nevertheless, the recovery of the superresolution information from the compressed measurement remains challenging in experiments. Here, we report structured illumination microscopy with complementary encoding-based compressive imaging (CECI-SIM) to realize faster super-resolution imaging. Compared to the nine measurements to obtain a super-resolution image in a conventional SIM, CECI-SIM can achieve a super-resolution image by three measurements;therefore, a threefold improvement in the imaging speed can be achieved. This faster imaging ability in CECI-SIM is experimentally verified by observing tubulin and actin in mouse embryonic fibroblast cells. This work provides a feasible solution for high-speed super-resolution imaging, which would bring significant applications in biomedical research.

关键词： illumination complementary faster

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基于电磁计算的同时极化雷达成像仿真

现代雷达 2024年第2期46卷 146-154页

作者：陈云张云华李东中国科学院国家空间科学中心微波遥感技术重点实验室北京100190 中国科学院大学电子电气与通信工程学院北京100049

雷达信号的电磁(EM)仿真对新体制雷达技术的研究具有重要价值。文中针对新体制同时极化雷达(SPR)回波信号开展EM仿真,提出了快速仿真方法,并在此基础上进行了高分辨雷达成像。首先,利用FEKO构建了雷达目标在4π空间里所有入射角度下的... 详细信息

雷达信号的电磁(EM)仿真对新体制雷达技术的研究具有重要价值。文中针对新体制同时极化雷达(SPR)回波信号开展EM仿真,提出了快速仿真方法,并在此基础上进行了高分辨雷达成像。首先,利用FEKO构建了雷达目标在4π空间里所有入射角度下的宽带全极化EM散射数据库;接着,在推导SPR目标回波信号模型的基础上,基于优化最小化方法以最小化互补积分旁瓣电平为准则设计了H、V发射通道的正交互补序列波形。最后,根据实际雷达对目标的视角和频率范围以调用数据库的方式“装配”得到相应的雷达回波信号。为了进一步验证所提方法,该文以F22模型为例开展了SPR成像仿真实验,并通过Pauli分解分析了幅相误差对目标极化散射特性测量的影响。

关键词：同时极化雷达电磁计算成像仿真互补序列

Effect of upward ion on field-aligned currents in the near-earth magnetotail

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science China(Physics,Mechanics & Astronomy) 2007年第5期50卷 673-680页

作者： zhang LingQian1, LIU ZhenXing1, MA ZhiWei2, SHEN Chao1, ZHOU XuZhi3 & zhang XianGuo3 1 center for space and applied research, Chinese Academy of sciences, Beijing 100080, China 2 Institute of Plasma Physics, Chinese Academy of sciences, Hefei 230031, China 3 School of Earth and space science, Peking University, Beijing 100871, China center for space and applied research Chinese Academy of Sciences Beijing China Institute of Plasma Physics Chinese Academy of Sciences Hefei China School of Earth and space science Peking University Beijing China

A 3-dimensional resistive MHD simulation was carried out to study the effect of the upward ions on the field-aligned currents (FACs) in the near-earth magnetotail. The simulation results show that the up-flow ions originating from the nightside auroral oval would drift into the center plasma sheet along the magnetic field lines in the plasma sheet boundary, and have an important effect on the field-aligned currents. The main conclusions include that: 1) the upward-ions mainly affect the field- aligned currents in the near-earth magnetotail (inside 15 Re); 2) the generated FACs in the near-earth region have two types, i.e., Region 1 FAC in the high-latitude and Region 2 FAC in the low-latitude; 3) FACs increase with the enhancement of the upward ion flux; 4) with the same flux of the upward ions, FACs enhance with the increase of the velocity of the up-flow ions; 5) the intensification of FACs is also closely related with the latitude of the upward ions, and the ions from the closed field line region generate larger FACs; 6) the generation of FACs is closely related with By created by the upward ions.

关键词： up-flow ions, near-earth magnetotail, field-aligned current