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arXiv 2020年

作者： Belkacem, Abdelkader Nasreddine Ouhbi, Sofia Lakas, Abderrahmane Benkhelifa, Elhadj Chen, Chao Department of Computer and Network Engineering CIT UAEU UAE Department of Computer Science and Software Engineering CIT UAEU UAE Cloud Computing and Applications Reseach Lab Staffordshire University United Kingdom Key Laboratory of Complex System Control Theory and Application Tianjin University of Technology China

Respiratory symptoms can be a caused by different underlying conditions, and are often caused by viral infections, such as Influenza-like illnesses or other emerging viruses like the Coronavirus. These respiratory viruses, often, have common symptoms, including coughing, high temperature, congested nose, and difficulty breathing. However, early diagnosis of the type of the virus, can be crucial, especially in cases such as the recent COVID-19 pandemic. One of the factors that contributed to the spread of the pandemic, was the late diagnosis or confusing it with regular flu-like symptoms. science has proved that one of the possible differentiators of the underlying causes of these different respiratory diseases is coughing, which comes in different types and forms. Therefore, a reliable lab-free tool for early and more accurate diagnosis that can differentiate between different respiratory diseases is very much needed. This paper proposes an end-to-end portable system that can record data from patients with symptom, including coughs (voluntary or involuntary) and translate them into health data for diagnosis, and with the aid of machine learning, classify them into different respiratory illnesses, including COVID-19. With the ongoing efforts to stop the spread of the COVID-19 disease everywhere today, and against similar diseases in the future, our proposed low cost and user-friendly solution can play an important part in the early diagnosis. Copyright © 2020, The Authors. All rights reserved.

关键词： Diagnosis

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A Infrared Cloud Image Simulation Method for Cloud Segmentation Network Training

A Infrared Cloud Image Simulation Method for Cloud Segmentat...

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International Applied Computational Electromagnetics Society Symposium (ACES)

作者： Hang Qi Jianquan Yuan Lei Li Jun Ren Jie Liang Science and Technology on Complex System Control and Intelligent Agent Cooperation Laboratory Beijing China Institute of Mechanical and Electrical Engineering Beijing China

ISBN: (数字)9780996007894

ISBN: (纸本)9781728146331

Due to the difficulty of acquiring real aerial infrared cloud images, we propose an efficient way to set up cloud simulation data set by particle system and texture synthesis, in order to alleviate the problem of data shortage. The deep network for cloud segmentation is trained on our simulation image data set, substantially decreasing the demand for real aerial cloud images. When testing on the real image data set, a satisfactory segmentation result with 79.64% has been reached which can meet the usage requirements. Our method can make the deep cloud segmentation network training feasible despite of the real image shortage, reducing the cost of data acquisition.

关键词： Clouds Image segmentation Data models Training Shape Image edge detection Force

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An Improved Robust Adaptive Kalman Filtering Algorithm

An Improved Robust Adaptive Kalman Filtering Algorithm

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第三十八届中国控制会议

作者： Liuyang Jiang Wenxing Fu Hai Zhang Zheng Li Longyun Chi School of Automation Science and Electrical Engineering Beihang University Science and Technology on Complex System Control and Intelligent Agent Cooperation Laboratory National Airspace Management Center

Robust adaptive Kalman filter(RAKF) is a method that can not only compensate for the model errors but also resist the measurement outliers. The method reduces the influence of the measurement outliers on the filtering system by reducing the weight of the abnormal observation. After the processing of robust estimation, all the errors are attributed to the inaccuracy of the model. Since the robust estimation is not theoretically quantitative that it can only reduce the observation error to a certain extent, the remaining observation errors are compensated as the model errors, resulting in new estimation errors. To address this problem, a method for detecting the model error is proposed as a trigger condition for RAKF to compensate for the model error,and this constitutes an improved robust adaptive Kalman filter(IRAKF) algorithm. The new algorithm performs the model errors compensation stricter than the original method. The efficacy of the improved algorithm is demonstrated via a traffic running testing with GPS/INS tight integration navigation system. Simulation results indicate that the improved algorithm can effectively reduce the inaccurate adaptive procedure and obtain relatively accurate and stable filtering results.

关键词： Adaptive Kalman Filter Robust Estimation Improved Model Errors Tight Integrated Navigation

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A Novel Geosynchronous Spaceborne-Airborne Bistatic Multichannel Sar For Ground Moving Targets Indication

A Novel Geosynchronous Spaceborne-Airborne Bistatic Multicha...

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IEEE International Symposium on Geoscience and Remote Sensing (IGARSS)

作者： Xichao Dong Wei Xiong Ying Zhang Cheng Hu Feifeng Liu School of Information and Electronics Beijing Institute of Technology Beijing China Science and Technology on Complex Electronic System Simulation Laboratory Space Engineering University Beijing China

Geosynchronous synthetic aperture radar (GEO SAR) has great potentials in synthetic aperture radar ground moving target indication (SAR-GMTI) due to its high time resolution and wide swath coverage. But the signal-to-noise ratio (SNR) of echo is too low and multichannel configuration cannot be realize in GEO monostatic SAR. Therefore, geosynchronous spaceborne-airborne bistatic multichannel synthetic aperture radar (GEO-SABM SAR) can realize enhanced SNR and multichannel configuration. In this paper, we establish the slant range model for GEO-SABM SAR and give the VSAR processing flowchart. Finally, the numerical experiments is given to verify the effectiveness of proposed method.

关键词： Synthetic aperture radar Clutter Doppler effect Imaging Flowcharts Orbits Remote sensing

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Range migration-based Doppler ambiguous integer estimation for moving targets with azimuth spectrum aliasing

Range migration-based Doppler ambiguous integer estimation f...

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Asian and Pacific Conference on Synthetic Aperture Radar (APSAR)

作者： Ying Zhang Wei Xiong Xichao Dong Cheng Hu Chengxiang Liu Yang Sun Science and Technology on Complex Electronic System Simulation Laboratory Space Engineering University Beijing China School of Information and Electronics Beijing Institute of Technology Beijing China

ISBN: (数字)9781728129129

ISBN: (纸本)9781728129136

In some case, the azimuth spectrum bandwidth is larger than the pulse repetition frequency (PRF), leading to a whole azimuth spectrum has been folded into multiple subsegments and aliased. Therefore, the traditional Doppler ambiguous integer estimation method cannot be used directly. In this paper, the influence of Doppler ambiguous integer on residual range migrations' slope is analyzed. Based on the slope, the Doppler ambiguous integer estimation method for moving targets with azimuth spectrum aliasing is given. From the simulation results, the Doppler ambiguous integer can be estimated accurately by proposed method.

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Radial Accelerated Velocity Estimation for Moving Ship Target Imaging based on GRFT in Geosynchronous SAR

Radial Accelerated Velocity Estimation for Moving Ship Targe...

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International Applied Computational Electromagnetics Society Symposium (ACES)

ISBN: (数字)9780996007894

ISBN: (纸本)9781728146331

GEO SAR has great potential in marine surveillance. But the extremely low SNR of echo, resulting in the traditional signal integration method become invalid. This paper proposes an improved GRFT-based approach to realize the moving ship targets' radial accelerated velocity estimation. Firstly, the accurate slant range is constructed which has considered the curved synthetic aperture trajectory. Then, the GRFT-based estimation method is redefined to realize radial accelerated velocity estimation and imaging. Finally, the simulation results are given to verify the proposed methods.

关键词： Acceleration Marine vehicles Synthetic aperture radar Estimation Imaging systems simulation Aerospace electronics

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Line-point feature based structure-preserving image stitching

Line-point feature based structure-preserving image stitchin...

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Chinese Automation Congress (CAC)

作者： Longyun Chi Xujun Guan Xiaorong Shen Hai Zhang School of Automation Science and Electrical Engineering Beihang University Beijing China Science and Technology on Complex System Control and Intelligent Agent Cooperation Laboratory Beijing China

The naturalness of the panoramic image is an important criterion for evaluating the result of image stitching. When the overlapping region of the image has a low-texture area, the alignment is hard to accomplish due to incorrect and inadequate feature point matching pairs, and the salient structures are easily destroyed due to the unreasonable position of the optimal seam. To solve the problem, we use line segment matching information to assist the alignment of low-texture regions and use superpixel segmentation regions to filter the unreliable point correspondences. An improved seam-finding algorithm is finally used to blend images together. The experimental results demonstrate that the proposed method can get more natural stitching results.

关键词： Image segmentation Strain Feature extraction Information filters Matched filters Optimization

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Amorphous alloys surpass E/10 strength limit at extreme strain rates

arXiv

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arXiv 2021年

作者： Zhu, Wenqing Li, Zhi Shu, Hua Gao, Huajian Wei, Xiaoding State Key Laboratory for Turbulence and Complex System Department of Mechanics and Engineering Science College of Engineering Peking University Beijing100871 China School of Mechanical and Aerospace Engineering College of Engineering Nanyang Technological University 70 Nanyang Drive 637457 Singapore Shanghai Institute of Laser Plasma China Academy of Engineering Physics Shanghai201102 China Institute of High Performance Computing A*STAR 138632 Singapore Beijing Innovation Center for Engineering Science and Advanced Technology Peking University Beijing100871 China Peking University Nanchang Innovation Institute Nanchang330000 China

Theoretical predictions of the ideal strength of materials range from E/30 to E/10 (E is Young’s modulus). However, despite intense interest over the last decade, the value of the ideal strength that can be attained experimentally for metals remains a mystery (1-5). In this study, we demonstrated the unprecedented strength of an amorphous Cu-Zr alloy that surpassed the E/10 limit. Laser-induced shock experiments were conducted on Cu50Zr50 to explore its strength and failure mechanisms at ultrahigh strain rates. The material demonstrated a high spall strength of 9.8 GPa, approximately 1/13 of its P-wave modulus (~ E/6), at strain rates greater than 107 s−1, which sets a new record for the elastic limit of metallic materials. Electron microscopy and large-scale molecular dynamics simulations revealed that void nucleation and growth, not shear-banding, comprised the major failure mechanism for metallic glasses at extremely fast strain rates. A new model for void formation under the control of surface energy explained the rate dependence of the material strength. The results of this study reveal new possible ways to use the amorphous phase in nanostructured metals in future applications under demanding mechanical conditions. Copyright © 2021, The Authors. All rights reserved.

关键词： Copper alloys

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Research on the Radio Frequency Simulation Method for Wide-band Radar complex Target based on Physical Optics and Physical Diffraction Theory

Research on the Radio Frequency Simulation Method for Wide-b...

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2019 IEEE International Conference on Signal, Information and Data Processing, ICSIDP 2019

作者： Guijier, DIao Hong, Ni Tianming, Zhan Yajing, Zhang Liang, Yang Science and Technology on Complex System Control and Intelligent Agent Cooperation Laboratory Beijing China Beijing Electro-mechanical Engineering Institute Beijing China Beijing Aerospace Smart Manufacturing Technology Development Co.Ltd. Beijing China Datang Mobile Communication Equipment Co. Ltd. Datang Telecom Group Beijing China

ISBN: (纸本)9781728123455

A radio frequency (RF) simulation technique based on high frequency hybrid method is proposed for complex target. Firstly, the radar cross section (RCS) of the target is obtained by vector addition of facets scattering field and wedges scattering field that are calculated respectively by physical optics (PO) method and physical theory of diffraction (PTD). Then, scattering centers of the target are extracted based on multi scattering center theory, and the radar echo signal is simulated through radio frequency simulation system (RFSS). This technique could improve the fidelity of radar signal simulation and the confidence of RF simulation test. At last, simulation results validate the technique. © 2019 IEEE.

关键词： Physical optics

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Optimal linear-quadratic guidance law considering autopilot first-order lag with terminal acceleration constraint

Optimal linear-quadratic guidance law considering autopilot ...

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Asia-Pacific International Symposium on Aerospace technology, APISAT 2018

作者： Zheng, Duo Xu, Xinghua Yan, Ruyi Lin, Defu Beijing Electro-Mechanical Engineering Institute Science and Technology on Complex System Control and Intelligent Agent Cooperation Laboratory Beijing100074 China Beijing Institute of Automatic Control Equipment Beijing100074 China Unit 95806 PLA Air Force Beijing100070 China School of Aerospace Engineering Beijing Institute of Technology Beijing100081 China

ISBN: (纸本)9789811333040

In this paper, a new optimal linear-quadratic guidance law with terminal acceleration constraints is proposed for intercepting maneuvering target. Because the angle of attack is approximately proportional to the normal acceleration for aerodynamic control missile, not only miss distance, but also terminal acceleration is required to converge to zero for increasing effectiveness of the warhead for destroying armored target in the proposed guidance law. The gain characteristic of proposed guidance law is studied by comparing with traditional optimal guidance law with considering autopilot dynamics lags. Numerical simulations are performed to examine performance of the proposed optimal guidance law, and its robustness with respect to the time constant of autopilot dynamic lags is also studied by considering time constant typical errors. © Springer Nature Singapore Pte Ltd. 2019.

关键词： Angle of attack

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