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International Applied Computational Electromagnetics Society Symposium (ACES)

作者： Yichun Cui Shengjun Zhang Mingliang Wang Jiaqi Liu Xin Liu Yue Wang National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing China

Large working bandwidth is now an attractive topic for FSS design, while it's hard to acquire a FSS structure with very wide bandwidth. So the way to actively tune the response frequency of the FSS, thus giving dynamic wide bandwidth maybe an available solution to this problem. In this paper, a two-layer structure loaded with variable capacitor was proposed to adjust resonance frequency. The upper layer employs strip lines and the lower layer joins capacitors between the cross rings to tune the frequency response curves of the whole structure quantitatively. This active frequency selective surface (AFSS) is sensitive to the change of loaded capacitance in some range while stay invariably above that, in which element can be regarded as being connected. Simulation results indicates that the rationality of analysis, which provides a general method to adjust resonance frequency and guides the active design of corresponding passive FSS in return.

关键词： Frequency selective surfaces Resonant frequency Capacitance Capacitors Equivalent circuits Integrated circuit modeling Bandwidth

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A Dual-Band Multilayer Heterogeneous Frequency Selective Surface with Miniaturized Unit Cell

A Dual-Band Multilayer Heterogeneous Frequency Selective Sur...

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2018 IEEE International Conference on Computational Electromagnetics, ICCEM 2018

作者： Cui, Yichun Zhang, Shengjun Liu, Jiaqi Liu, Xin Xue, Hui Zhang, Borong National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing100076 China Beijing Institute of System Engineering Beijing China Beijing Institute of Astronauctical Systems Engineering Beijing100076 China

ISBN: (纸本)9781538612415

In terms that most researches about Frequency Selective Surface (FSS) concentrate on single layer structure design or FSS with one fundamental mode, a multilayer heterogeneous dual-band frequency selective surface composed of slot FSS, dielectric medium, patch FSS is proposed. This FSS possess miniaturized unit cell with dimension of 6× 6mm2, it acts as a dual-band filter in given bands while behaving as an entire reflector in others. Results show that this dual-band frequency selective surface has narrow transmission bandwidths near 8.5GHz and 19.5GHz and flat rejection bands except for that. The structure exhibits excellent stability for oblique incident angles and provides polarization-independent response with compact design which moves the operating bands away from grating lobes. A method to adjust the element's size is proposed as well based on basic elements when given pass band frequency changed. © 2018 IEEE.

关键词： Frequency selective surfaces

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A Dual-Band Multilayer Heterogeneous Frequency Selective Surface with Miniaturized Unit Cell

A Dual-Band Multilayer Heterogeneous Frequency Selective Sur...

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IEEE International Conference on Computational Electromagnetics (ICCEM)

作者： Yichun Cui Shengjun Zhang Jiaqi Liu Xin liu Hui Xue Borong Zhang National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing China National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing 100076 China Beijing Institute of System Engineering Beijing China

ISBN: (纸本)9781538612422

In terms that most researches about Frequency Selective Surface (FSS) concentrate on single layer structure design or FSS with one fundamental mode, a multilayer heterogeneous dual-band frequency selective surface composed of slot FSS, dielectric medium, patch FSS is proposed. This FSS possess miniaturized unit cell with dimension of 6×6mm 2 , it acts as a dual-band filter in given bands while behaving as an entire reflector in others. Results show that this dual-band frequency selective surface has narrow transmission bandwidths near 8.5GHz and 19.5GHz and flat rejection bands except for that. The structure exhibits excellent stability for oblique incident angles and provides polarization-independent response with compact design which moves the operating bands away from grating lobes. A method to adjust the element's size is proposed as well based on basic elements when given pass band frequency changed.

关键词： electromagnetic wave polarisation frequency selective surfaces microwave filters multilayers frequency selective surfaces electromagnetic wave polarisation Microwave filters unit cell multilayers Dual band belt cleaner compact design

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Station Layout Optimization Genetic Algorithm for Four Stations TDOA Location

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Journal of physics: Conference Series 2019年第6期1176卷

作者： Ruiqi Sun Zhonghang He Lu Gao Jinliang Bai National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing 100076

Station layout has a direct impact on localization precision for four-station TDOA (time difference of arrival) location system. In order to optimize the overall location precision of targets in certain area, genetic algorithm for station layout optimization is presented. GDOP is regarded as the measurement rule of location precision. Then the multi-object programming mathematical model of station layout optimization is built. The optimal solution is searched by genetic algorithm. Consequently, the optimal layout of station is obtained. The simulation provides the GDOP distribution of two station layouts. One is the initial station layout, and the other is the optimal station layout. The simulation results show that for the optimal station layout, the effect of improving the location precision is obvious, and also indicate the validity of genetic algorithm.

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Study of RF structure and Beam Wave Interaction system for a W-band Sheet Beam EIK

Study of RF structure and Beam Wave Interaction system for a...

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2017 International Conference on Radar Systems, Radar 2017

作者： Chen, Shuyuan Liu, Jiaqi Gao, Lu Bai, Jinliang Jiang, Zhiye Xu, Feng Qin, Peng Liu, Hongyan Liu, Xin Li, Hu Gao, Jingpeng National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing100076 China

ISBN: (纸本)9781785615153

Sheet beam Extended Interaction Klystron (EIK) is an attractive Millimeter Waves (MMW) amplifier because of its high gain per unit length and compact configuration, which can be used in radar transmission system. In this paper, RF structure and beam wave interaction system of W band sheet beam EIK has been designed. A new and effective method of designing and studying the beam wave interaction system is presented in this *** whole tube consists of one single-gap cavity, six tri-gaps cavities and one five-gaps cavity. By optimizing the position of cavities, the output power can achieve 30 kW and high gain of 50 dB, which is calculated by three dimensional particle in cell (3D-PIC)*** provides a powerful basis for the subsequent study of sheet beam EIK. © 2017 Institution of Engineering and technology. All rights reserved.

关键词： Millimeter waves

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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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The way from natural to artificial - The story of periodic electromagnetic structures

The way from natural to artificial - The story of periodic e...

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2017 International Applied Computational Electromagnetics Society Symposium in China, ACES-China 2017

作者： Zhang, Shengjun Wang, Mingliang Ai, Xia Wang, Weidong Wu, Runhui Liu, Xin Liu, Jiaqi Meng, Gang Sun, Yuan National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing China Institute of Effectiveness Evaluation of Flying Vehicle Beijing China

In this paper, the general of artificial electromagnetic structure with analog to the natural materials were briefly reviewed. The lattice theory of artificial structure was suggested to be built. © 2017 Applied ... 详细信息

ISBN: (纸本)9780996007856

关键词： Lattice theory

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A Novel Gcv-Based Criterion for Parameter Selection In Image Deconvolution

A Novel Gcv-Based Criterion for Parameter Selection In Image...

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IEEE International Conference on Acoustics, Speech and Signal Processing

作者： Feng Xue Thierry Blu Jiaqi Liu Xia Ai National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing 100076 China Dept. of Electronic Engineering The Chinese University of Hong Kong Shatin N.T. Hong Kong

ISBN: (纸本)9781538646595

A proper selection of regularization parameter is essential for regularization-based image deconvolution. The main contribution of this paper is to propose a new form of generalized cross validation (GCV) as a criterion for this optimal selection. Incorporating a nil-trace non-linear estimate, we develop this new GCV based on Stein's unbiased risk estimate (SURE)-an unbiased estimate of mean squared error (MSE). The key advantage of this GCV over SURE is that it does not require the knowledge of noise variance. We exemplify this criterion with both Tikhonov regularization and l_1-based sparse deconvolution. In particular, we develop a recursive evaluation of GCV for the l_1-estimate based on iterative soft-thresholding (IST) algorithm. numerical experiments demonstrate the nearly optimal parameter selection and negligible loss of its resultant deconvolution quality.

关键词： Image deconvolution regularization parameter generalized cross validation (GCV) Stein's unbiased risk estimate (SURE) deconvolution Mean square error optimal selection optimal parameter Imagery (Psychotherapy) Image images

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The Probability Density Function for Network Coding with Three Input Flows

The Probability Density Function for Network Coding with Thr...

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International Conference on Computers, Communications, and Systems (ICCCS)

作者： Xiangrong Liu Yaping Liang Qing Chang Xianxu Li National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing China School of Electronic Information Engineering Beihang University Beijing China State grid information & communication branch Beijing China

ISBN: (纸本)9781538663516

Now many researches have been studying the optimization between throughput/energy consuming and delay with a couple of independent input flows in network coding (NC). However, the implementation of network coding (NC) requires a thorough investigation of its impact on relevant queueing systems which little work focuses on. In this paper, the scenario with three independent Poisson input flows based on our previous work about the pdf with two independent Poisson input flows., and one output flow is considered. The asynchronous NC-based strategy is that a new arrival evicts a head packet holding in its queue when waiting for another packet from the other flow to encode. The three flows are divided into two parts for getting the probability density function (pdf) of the output flow. The pdf for the output flow which contains both coded and uncoded packets is derived. Besides, the statistic characteristics of this strategy are analyzed. These results are verified by numerical simulations.

关键词： Probability density function Network coding Encoding Relays Merging Simulation numerical simulation

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Recursive Evaluation of Sure for Total Variation Denoising

Recursive Evaluation of Sure for Total Variation Denoising

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IEEE International Conference on Acoustics, Speech and Signal Processing

ISBN: (纸本)9781538646595

Recently, total variation (TV)-based regularization has become a standard technique for signal denoising. The reconstruction quality is generally sensitive to the value of regularization parameter. In this work, based on Cham-bolle's algorithm, we develop two data-driven optimization schemes based on minimization of Stein's unbiased risk estimate (SURE)-statistically equivalent to mean squared error (MSE). First, we propose a recursive evaluation of SURE to monitor the estimation error during Chambolle's iteration;the optimal value is then identified by the minimum SURE. Second, for fast optimization, we perform alternating update between regularization parameter and solution within Chambolle's iteration. We exemplify the proposed methods with both 1-D and 2-D signal denoising. numerical experiments show that the proposed methods lead to highly accurate estimate of regularization parameter and nearly optimal denoising performance.

关键词： Signal denoising total variation (TV) Stein's unbiased risk estimate (SURE) Chambolle's algorithm

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