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Beam scan mode analysis and design for geosynchronous SAR

Science China(information Sciences) 2017年第6期60卷 72-84页

作者： Wei YIN Zegang DING Xiaojun LU Yu ZHU Beijing Key Laboratory of Embedded Real-time Information Processing Technology School of Information and Electronics Beijing Institute of Technology Beijing Institute of Spacecraft System Engineering Chinese Academy of Space Technology

The beam velocity of geosynchronous synthetic aperture radar(GEO SAR) varies seriously with the orbital position and the scene position, which leads to a significant variation of the scene length and the azimuth resolution in the stripmap(SM) mode. To obtain uniform scene length and azimuth resolution, beam scan modes can be utilized in GEO SAR, such as the sliding spotlight(SLL) mode and the terrain observation by progressive scans(TOPS) mode. However, the conventional design method of the beam scan mode is based on the straight line model(SLM), which does not consider the effects of the curved satellite track and the spherical earth surface. To solve this problem, a curvature circle model(CCM) is proposed considering the actual satellite-earth relationship. By using the CCM, the beam velocity after the beam scan is derived. The scene length and the azimuth resolution are analyzed. The SLL mode and the TOPS mode are recommended for GEO SAR. After that, a design method of the beam scan mode is proposed based on the CMM. The performance of the proposed method is verified by computer simulations.

关键词： GEO SAR beam scan mode design azimuth resolution scene length

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Change detection in optical remote sensing images based on watershed segmentation

Change detection in optical remote sensing images based on w...

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IET International Radar Conference 2015

作者： Mai, Zhihong Shi, Hao Xie, Yizhuang Ma, Long Bejing Key Laboratory of Embedded Real-Time Information Processing Technology Beijing Institute of Technology Beijing100081 China

ISBN: (纸本)9781849199940

A novel approach is presented for change detection of very high resolution (VHR) remote sensing images in this paper, which is achieved by an improved watershed segmentation and mutual correlation. Specifically, the input multitemporal images are watershed segmented separately in the first stage. And then fuse the segmentation regions of two segmented images, which is also a combination of object outlines in other words. Finally, the change mask can be acquired by the mutual correlation method. Experimental results show the superiority of the proposed method over the Markov random filed (MRF) method to the VHR urban optical remote sensing images.

关键词： Change detection

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Merging Clinical Knowledge into Large Language Models for Medical Research and Applications: A Survey

arXiv

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arXiv 2025年

作者： Li, Qiyuan Liu, Haijiang Guo, Caicai Chen, Deyu Wang, Meng Gao, Feng Gu, Jinguang College of Computer Science and Technology Wuhan University of Science and Technology Hubei Wuhan430065 China Hubei Province Key Laboratory of Intelligent Information Processing and Real-time Industrial System Hubei Wuhan430065 China The Key Laboratory of Rich-Media Knowledge Organization Service of Digital Publishing Content Institute of Scientific and Technical Information of China Beijing100038 China School of Computer Science and Technology Huazhong University of Science and Technology Hubei Wuhan430074 China School of Cyber Science and Engineering Wuhan University Hubei Wuhan430072 China

Clinical knowledge is the collection of information learned from studies on the causes, prognosis, diagnosis, and treatment of diseases. This type of knowledge can improve curing performances, and promote physical health. With the emergence of large language models (LLMs), medical artificial intelligence (medical AI), which aims to apply academic medical AI systems to real-world medical scenarios, has entered a new age of development, resulting in excellent works such as DoctorGPT and Pangu-Drug from academic and industrial researches. However, the field lacks a comprehensive compendium and comparison of building medical AI systems from academia and industry. Therefore, this survey focuses on the building paradigms of medical AI systems including the use of clinical databases, datasets, training pipelines, integrating medical knowledge graphs, system applications, and evaluation systems. We hope that this survey can help relevant practical researchers understand the current performance of academic models in various fields of healthcare, as well as the potential problems and future directions for implementing these scientific achievements. Copyright © 2025, The Authors. All rights reserved.

关键词： Clinical research

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Signal Intergrity Analysis for SMA Via on the PCB 9

Signal Intergrity Analysis for SMA Via on the PCB

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2017 9th IEEE International Conference on Communication Software and Networks (ICCSN 2017)

作者： Rongrong Ben Shanqing Hu Xingming Li Zhen Fu Beijing Key Laboratory of Embedded Real-time Information Processing Technology Beijing Institute of Technology

ISBN: (纸本)9781509038237;9781509038220

SMA connector is widely used in the high-speed interconnection system. As more designs move toward highspeed serial links with picosecond edge rate, the signal integrity problems caused by the transition structure from SMA connector to the PCB cannot be neglected, especially for precise AFR calibration. To solve this problem, we present four optimization methods, including optimizing the size of anti-pad, back-drilling, adding GND vias around the signal vias and providing a diving board, which are investigated by HFSS. Finally, by testing two different commonly-used SMA connectors, we can see that the bandwidth after optimization is at least twice as high as that before the optimization. This effectively overcomes the signal effective bandwidth limitations brought by discontinuous impedance and ensures the accuracy of high-speed link verification.

关键词： SMA connectors HFSS signal integrity optimization

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A waterborne salient ship detection method on SAR imagery

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Science China(information Sciences) 2015年第8期58卷 193-196页

作者： MA Long CHEN Liang ZHANG XueJing CHEN He Nouman Qadeer SOOMRO Beijing Key Laboratory of Embedded Real-Time Information Processing Technology Beijing Institute of Technology College of Information Technology Beijing Union University School of Computer Science Beijing Institute of Technology

Dear editor,Synthetic aperture radar(SAR)is a powerful electro-optic sensor for maritime use regardless of impact of time and meteorological ***,ship detection plays an important role in maritime

关键词： SAR A waterborne salient ship detection method on SAR imagery Figure

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Simulation and Analysis of the Impacts of Anisotropic Ionospheric Scintallition on Geosynchronous Synthetic Aperture Radar

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Journal of Beijing Institute of technology 2017年第1期26卷 115-120页

作者： Yinhui Xu Xichao Dong Cheng Hu Yuanhao Li School of Information and Electronics Beijing Institute of Technology Beijing 100081 China Beijing Key Laboratory of Embedded Real-time Information Processing Technology Beijing 100081 China

The impacts of ionospheric scintillation on geosynchronous synthetic aperture radar（GEO SAR）focusing is studied based on the multiple phase screen（MPS）*** power spectrum density of electron irregularities is first modified according to the ionospheric *** propagation wave equations in random medium are deduced in the case of oblique incidence in GEO *** amplitude and phase errors induced by the random electron fluctuations are generated by the iterated MPS simulations and are superimposed into the GEO SAR *** the following imaging and evaluation,the effects of the anisotropic ionospheric scintallition on GEO SAR are *** last,the optimized integration time under different ionospheric scintillation conditions are recommended through Monte Carlo *** is concluded that,greater ionospheric fluctuations and longer integration time will result in more severe deterioration,even no focus at all in the worst case.

关键词： anisotropy focusing geosynchronous synthetic aperture radar （GEO SAR） ionospher-ic scintillation multiple phase screen

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Virtual single-node processing for SAR imaging based on multi-DSP

Virtual single-node processing for SAR imaging based on mult...

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2016 IEEE International Conference on Signal processing, Communications and Computing, ICSPCC 2016

作者： Ye, Jin Shanqing, Hu Jiayun, Zhao Teng, Long Beijing Key Laboratory of Embedded Real-time Information Processing Technology Beijing China

ISBN: (纸本)9781509027088

With the development of SAR technology, the SAR imaging processing data capability and computation complexity increases greatly. According to the situation, we design a virtual single node (VSN) parallel processing method, which uses 8 TMS320C6678 DSPs as a big processor to realize the large capability distributed storage and short time delay of SAR imaging processing. This method designs a remote reading and writing time beat of range line and azimuth line in distributed DDR to improve the remote transmission bandwidth between DSPs, and a data layout optimization approach in local DDR to achieve a balanced two-dimensional matrix local storage bandwidth. Finally, this paper realizes the SAR imaging algorithm based on the VSN method using 8 C6678s. © 2016 IEEE.

关键词： Digital storage

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SAR Parameter Estimation Method for Rectangle Plane Based on information Geometry

SAR Parameter Estimation Method for Rectangle Plane Based on...

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2019 IEEE International Conference on Signal, information and Data processing, ICSIDP 2019

作者： Wen, Yuhan Chen, Xinliang Wei, Yangkai Fan, Yujie Zeng, Tao DIng, Zegang Beijing Key Laboratory of Embedded Real-time Information Processing Technology Beijing China

ISBN: (纸本)9781728123455

After establishing scattering models, the traditional synthetic aperture radar (SAR) parameter estimation methods usually utilize vanilla gradients to estimate target parameters from SAR echoes or images. However, the vanilla gradients will lead to lower iteration efficiency. Hence, in this paper, to take the rectangle plane as an example, we propose a SAR parameter estimation method based on the information geometry (SPEM-IG) to solve the above problem. The SPEM-IG adopts the natural gradient to estimate the parameters based on the information geometry optimization algorithm. The central objective of SPEM-IG is to project the least square function into probability distribution space and find the optimal solution in the new parameter space. In order to reduce the computational complexity caused by the multi-peak feature of least squares function, SPEM-IG utilizes the range of parameters rather than its exact value in calculating the value of least squares function, and takes the optimal solution in this range as the result of the current iteration process. By considering the geometric structure of manifolds, SPEM-IG calculates the optimal gradient direction called natural gradient to obtain faster convergence rate. The experimental results show that the SPEM-IG is effective for estimating target parameters. Besides, SPEM-IG has good performance even at low signal-to-noise ratios of SAR images. © 2019 IEEE.

关键词： Synthetic aperture radar

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SAR Tomography with Improved Non-Local Means Filtering Based on Adaptive Window

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Journal of Beijing Institute of technology 2023年第6期32卷 670-684页

作者： Shenglei Wang Zhiyang Chen Yuanhao Li Cheng Hu Radar Research Laboratory School of Information and ElectronicsBeijing Institute of TechnologyBeijing 100081China Key Laboratory of Embedded Real-time Information Processing Technology Beijing Institute of TechnologyBeijing 100081China

In order to mitigate speckle noise in synthetic aperture radar(SAR)images and enhance the accuracy of SAR tomography,non-local means(NL-means)filtering has been proven to be an effective method for improving the quality of SAR *** from considerations like noise type and the definition of similarity,the size and shape of filtering windows are critical factors influencing the efficacy of NL-means filtering,yet there has been limited research on this *** paper introduces an enhanced NL-means filtering method based on adaptive windows,allowing for the automatic adjustment of filtering window size according to the amplitude information of the SAR ***,a directional window is incorporated to align SAR interferograms,achieving the dual objective of preserving filtering standards and retaining detailed *** results on interferogram filtering and tomography,based on TerraSAR-X data,demonstrate that the proposed method effectively reduces phase noise while maintaining texture accuracy,thereby improving tomography quality.

关键词： NL-means filter adaptive window SAR interferogram filtering SAR tomography

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An autofocusing imaging algorithm for wall penetrating SAR

An autofocusing imaging algorithm for wall penetrating SAR

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IET International Radar Conference 2015

作者： Liu, Wei Zheng, Meng Xiang, Yin Ding, Zegang Zeng, Tao Beijing Key Laboratory of Embedded Real-Time Information Processing Technology Beijing Institute of Technology China

ISBN: (纸本)9781849199940

The absence of wall's characteristic will smear and blur the image, shift the target position, and even defocus the imaging result. To solve the problems, a novel autofocusing imaging algorithm is proposed in this paper. Firstly, the electromagnetic field is employed as a 2-D matching filter during the imaging processing. Then, the electromagnetic field in the airto-wall medium is replaced by that in the air-to-air medium. Thirdly, the mismatching error, which is proved to be an extra frequency gap at the shifted depth, is compensated by using the phase cross-correlation method. Finally, the correctness and efficiency of the proposed method are verified by the full wave simulation with data from CST.

关键词： Electromagnetic fields

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