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IET International Radar Conference 2018, IRC 2018

作者： Liu, Hong Yan Zheng, Pei Wang, Chao Guo, Lei Zhang, Xin Yu National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing China

In this study, the near-field beam focusing algorithm of reconfigurable reflect array for security imaging application is proposed. The proposed near-field focusing algorithm is based on classic array method, which is usually adopted for far-field pattern calculation. In order to satisfy the near-field imaging application, the imaging distance is added to array method, and the improved formula can calculate the shifting phase of every array element precisely. In addition, due to discrete phase characteristic of reconfigurable reflect array, a phase choice method based on trigonometric function is used in authors' design. Based on the proposed algorithm, the shifting phase of every element is calculated and obtained the simulated beam focusing patterns. Meanwhile, the calculated shifting phase is written to whole array by field-programmable gate array, the near-field beam scanning patterns is measured and the measured results are in good agreement with the simulated ones. © 2019 Institution of Engineering and technology. All rights reserved.

关键词： Field programmable gate arrays (FPGA)

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Application of Graphic Electromagnetic Computing in Electrically Large Scale Composite Target Scattering

Application of Graphic Electromagnetic Computing in Electric...

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2022 International Applied Computational Electromagnetics Society Symposium, ACES-China 2022

作者： Gao, Lu Fang, Ning Wang, Mingliang Liu, Jiaqi Li, Yanan Wu, Runhui Xu, Yinfang National Key Laboratory of Science and Technology on Test Physics & Numerical Mathematics Beijing China Beihang University Academy of Electronic Information Engineering Beijing China National Key Laboratory of Science and Technology on Test Physics Beijing China

ISBN: (纸本)9781665452366

The radar cross section(RCS) calculation model of electrically large-scale composite target is established by combining graphic electromagnetic computing(GRECO) with high-frequency optical approximation and physical diffraction. Using different illumination modes, the normal vector at each point on the target surface is obtained, and the total scattering field of the target is acquired by the coherent superposition of the scattering field and the diffraction field at each point on the target surface. © 2022 IEEE.

关键词： Radar cross section

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Unmanned aerial vehicle infrared detector simulation modelling and performance analysis

Unmanned aerial vehicle infrared detector simulation modelli...

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2017 IASTED International Conference on Modelling, Identification and Control, MIC 2017

作者： Liu, Fang Liu, Xin Liu, Jiaqi National Key Laboratory of Science and Technology On Test Physics and Numerical Mathematics Nandahongmen Road No.1 Beijing China

ISBN: (纸本)9780889869882

An observation model of unmanned aerial vehicle(UAV) infrared detector is developed. The visibility criterion is derived via geometric relationships between the infrared detector, target and earth, the constraint of the detector's frame angle, and the detection range of infrared detector. Because of the infrared sensor can only obtain the angular information of the target, so it is impossible for one detector to locate position of the target. The position of the target is obtained by two or more detectors. The least square method based multi-sensor target tracking method is introduced. It is important to set a filter before using the tracking data as there are observation errors caused by UAV position error, UAV attitude error, sensor pointing error and sensor image plane position error. The extend Kalman Filter (EKF) algorithm is used to smooth the tracking signals. Finally, two UAV infrared detectors observing a low-orbit target is simulated for their observation performance. The result shows that the infrared detectors can observe the target within the scope of the detection range. When the target flies off the top of the UAV, the detectors can't observe it because of the constraint of the frame angle. The observation error is reduced substantially after the EKF is used.

关键词： Infrared detectors

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Predicting Electromagnetic Response of Electromagnetic Metasurface using Deep Learning 15

Predicting Electromagnetic Response of Electromagnetic Metas...

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15th International Conference on Signal Processing Systems, ICSPS 2023

作者： Yang, Bingyan Wang, Qiong Mu, Lei School of Electronic Science and Engineering Nanjing University China Key Laboratory of Science and Technology on Test Physics & Numerical Mathematical Beijing100076 China

ISBN: (纸本)9781510675056

Digitally coded metasurface(DMS) is a novel class of electromagnetic materials that possess the ability to manipulate electromagnetic waves at scales significantly smaller than the wavelength. They hold great potential for a wide range of applications, including wireless communication, millimeter-wave imaging, data storage, and sensing. However, the conventional full-wave simulation methods currently employed often require precise geometric modeling, grid planning, and consideration of complex physical models such as material parameters and boundary conditions. These time-consuming and costly approaches face significant challenges in large-scale electromagnetic response studies. Therefore, there is an urgent need to explore more efficient and cost-effective methods to address these issues. In this paper, we propose a deep learning-based approach for predicting the electromagnetic response of individual units in a DMS. We construct a convolutional neural network (CNN) model that can accurately and real-time predict the electromagnetic response based on the input coding pattern. To train and validate the model, we utilize a substantial amount of electromagnetic simulation data and incorporate amplitude constraints into the loss function for model optimization. A way to abandon the dual network structure and achieve simultaneous prediction of dual parameters with smaller computational requirements. Experimental results demonstrate that our model achieves highly accurate predictions of both amplitude and phase responses of DMS, surpassing traditional numerical methods in terms of efficiency and scalability. The proposed deep learning approach offers a promising solution for efficient and low-cost prediction of electromagnetic responses in DMS. © 2024 SPIE.

关键词： Neural network models

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Real-Time Path Planning based on the Lock Loss Model

Real-Time Path Planning based on the Lock Loss Model

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2022 International Applied Computational Electromagnetics Society Symposium, ACES-China 2022

作者： Luo, Xun Liu, Li Liu, Xin National Key Laboratory of Science and Technology on Test Physics & Numerical Mathematical Beijing China China Academy of Launch Vehicle Technology Beijing China

ISBN: (纸本)9781665452366

A new method of aircraft low altitude penetration is proposed with temporal constraints that allow periods of high observability interspersed with periods of low observability. The aircraft's RCS character is simplified into the 'bow-tie' distribution, then the aircraft can dynamically adjust its yaw angle to minimize the risk from the radars. According to the modified Lock Loss model and the TWS(Track While Scan) radar work flow, and real-time evaluating model on the original path, a fast real-time path planning method is present on the situation that unexpected threats occur. An example of real-time path planning is given. © 2022 IEEE.

关键词： Locks (fasteners)

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Adaptive feed-forward control for seeker based on the disturbance observer 4

Adaptive feed-forward control for seeker based on the distur...

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4th IEEE Advanced Information technology, Electronic and Automation Control Conference, IAEAC 2019

作者： Liu, Xin Niu, Zhenhong Shu, Yi Xue, Lian Zhu, Mingchao National Key Laboratory of Science and Technology on Test Physics Numerical Mathematics China Chinese Academy of Sciences Changchun Institute of Optics Mechanics and Physics China

ISBN: (纸本)9781728119076

In order to improve the tracking and stabilization performance, a control method combining disturbance observer and adaptive feed-forward control using parameterization is proposed for seeker stabilized platforms. The system identification algorithm is used to identify dynamic model of the true plant. Then the discrete-time disturbance observer is designed. The feedback loop controller is designed using pole-placement techniques. The recursive least square (RLS) adaptive filter is used to build the inverse model of the feedback control loop and in this way, the feed-forward control is constructed. The adaptive filter and the feedback loop constitute a control scheme with two degrees-of-freedom (DOF). Tracking experiments conducted on velocity command inputs verify the validity of the adaptive feed-forward controller. Experimental results show that this method responses quickly to commands. For a sinusoidal signal at the frequency of 30Hz, the adaptive feed-forward controller can obtain an amplitude response without attenuation and the phase lag is reduced to 11° in contrast with the feedback control whose phase lag is 60°. This method significantly improves the transient performance and is superior to the feedback control alone. © 2019 IEEE.

关键词： Adaptive filters

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1-bit Coding Metasurface for Wideband RCS Reduction

1-bit Coding Metasurface for Wideband RCS Reduction

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2022 International Applied Computational Electromagnetics Society Symposium, ACES-China 2022

作者： Xu, Yinfang Liu, Jiaqi Gao, Lu Ai, Xia Zhang, Zhongjie Liang, Huan Beijing Institute of Space Long March Vehicle National Key Laboratory of Science and Technology on Test Physics & Numerical Mathematics Beijing China

ISBN: (纸本)9781665452366

This paper achieve efficient RCS reduction over a wide frequency range by exploiting the reflection properties of the coding metasurface. The metasurface consists of '0' cells and '1' cells, and the reflection phase difference is close to 180° over a wide frequency range. By designing the spatial random coding arrangement of '0' units and '1' units, the electromagnetic waves incident on the metasurface form diffuse reflection, so as to achieve the purpose of broadband RCS reduction. The simulation results show that when the incident wave is irradiated vertically, the metasurface can basically achieve a RCS reduction of more than 10dB in a wide frequency band of 10-20.5GHz compared to a metal plate of the same size. In the case of oblique incidence, the RCS reduction still has a good effect, which is basically the same as the curve at normal incidence, and has the characteristics of wide-angle incidence RCS reduction. The reduced bandwidth of the broadband RCS of the coding metasurface is basically consistent with the 10 dB polarization bandwidth of the cell structure. The design of the metasurface is simple and efficient, so it has great application potential in stealth new technologies and new materials. © 2022 IEEE.

关键词： Plate metal

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Multiple model PHD filter for tracking sharply maneuvering targets using recursive RANSAC based adaptive birth estimation

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Journal of Systems Engineering and Electronics 2024年第3期35卷 780-792页

作者： DING Changwen ZHOU Di ZOU Xinguang DU Runle LIU Jiaqi School of Astronautics Harbin Institute of TechnologyHarbin 150001China School of Electronics and Information Engineering Harbin Institute of TechnologyHarbin 150001China National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing 100076China

An algorithm to track multiple sharply maneuvering targets without prior knowledge about new target birth is proposed. These targets are capable of achieving sharp maneuvers within a short period of time, such as drones and agile *** probability hypothesis density (PHD) filter, which propagates only the first-order statistical moment of the full target posterior, has been shown to be a computationally efficient solution to multitarget tracking problems. However, the standard PHD filter operates on the single dynamic model and requires prior information about target birth distribution, which leads to many limitations in terms of practical applications. In this paper,we introduce a nonzero mean, white noise turn rate dynamic model and generalize jump Markov systems to multitarget case to accommodate sharply maneuvering dynamics. Moreover, to adaptively estimate newborn targets’information, a measurement-driven method based on the recursive random sampling consensus (RANSAC) algorithm is proposed. Simulation results demonstrate that the proposed method achieves significant improvement in tracking multiple sharply maneuvering targets with adaptive birth estimation.

关键词： multitarget tracking probability hypothesis density(PHD)filter sharply maneuvering targets multiple model adaptive birth intensity estimation

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An Ultra Wideband FSS Operating at Ka Band 5

An Ultra Wideband FSS Operating at Ka Band

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5th IEEE International Conference on Computational Electromagnetics, ICCEM 2019

作者： Xu, Yinfang Zhang, Shengjun National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing Institute of Space Long March Vehicle Beijing China

ISBN: (纸本)9781538671115

An Ultra Wideband frequency selective surface (FSS) with forth-order bandpass responses operating at Ka band is proposed in the paper. To improve the performance of the FSS especially in angular stability, the coupling of capacitive surface and inductive surface is employed to realize the miniaturization of the structural unit around 0.26λ. Furthermore, to enhance the passband and to suppress sharply the bandstop edge of the FSS, a multi-layer FSS structure is adopted to form a forth-order filter. In addition, the FSS working at the Ka band frequency with a low-profile broadband and a high rejection stopband is designed. The proposed FSS can provide sharp frequency selectivity and stable frequency responses as functions of angle and polarization of incidence of the EM wave. Principles of operation, detailed design, and simulated results of the fabricated prototypes are presented and discussed in this paper. © 2019 IEEE.

关键词： Frequency selective surfaces

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Theoretical Simulation and Experimental Analysis of Electromagnetic Wave Propagation characteristics in Sub-dense Nonuniform Plasma 4

Theoretical Simulation and Experimental Analysis of Electrom...

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4th International Applied Computational Electromagnetics Society Symposium in China, ACES-China 2021

作者： Wu, Runhui Liu, Jiaqi Chai, Song Meng, Gang Li, Yanan Cui, Yichun Beijing Institute of Space Long March Vehicle National Key Laboratory of Science and Technology on Test Physics Numerical Mathematics Beijing China

In this paper, reflection, absorption and transmission characteristics of 1-50GHz frequency electromagnetic wave by the sub-dense heterogeneous plasma are studied by combining theoretical modeling and simulation with ... 详细信息

ISBN: (纸本)9781733509619

关键词： Computation theory

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