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IET International Radar Conference 2018, IRC 2018

作者： Wang, Ming-Liang Liu, Jia-Qi Xin, Liu Zhao, Xin-Ying Zhang, Sheng-Jun Lei, Mu Xia, Ai Guobin, Wan Wang, Wei-Dong Zhao, Ju-Yan National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematical Beijing100076 China Northwestern Polytechnical University Xi'an710072 China

To realise wide-band stealth of radar absorbing material, a special-shaped honeycomb radar absorbing structure within nested cone-shaped scattering configuration is designed. Based on the HS theory and the impedance matching design, the rule about the influence of the geometry parameter and electromagnetic parameter on the absorbing performance is analysed. In addition, the reflectivity performance is analysed on the condition of oblique incidence angles. By optimising the geometry parameters of the special-shaped honeycomb structure and designing the multilayer composite structure based on impedance matching theory, the results indicate that the two absorbing peaks can be formed for the special-shaped honeycomb radar absorbing structure, and the reflectivity is improved for both the vertical and oblique incidence angles. © 2019 Institution of Engineering and technology. All rights reserved.

关键词： Reflection

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Complex forward scattering coefficient for signal characterisation

Complex forward scattering coefficient for signal characteri...

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IET International Radar Conference 2018, IRC 2018

作者： Chen, Jing Liu, Xiangrong Liu, Changjiang Dong, Xichao School of Information and Electronics Beijing Institute of Technology Beijing China Beijing Key Laboratory of Embedded Real-time Information Processing Technology Beijing China National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics 100076 China

In this study, modelling and characteristics analysis of forward scattering coefficients and echoes are investigated. Traditional ground-target forward scattering signal model has not considered the impact of scattering phase;thus it is not accurate enough for describing air-target echoes. To solve this problem, a novel echo model was proposed based on the analytical deduction of complex forward scattering coefficient. The novel model separately expresses the target scattering characteristics and Doppler, greatly facilitating the theoretical analyses of echo characteristics. Then, theoretical and simulation investigations on the amplitude and phase characteristics of forward scattering echoes were made based on the complex forward scattering coefficient model. Theoretical explanations for the periodical fluctuation of far-field echo amplitude, periodical saltation of far-field echo phase, shadow blocking of near-field echo amplitude, and slow variation of near-field echo phase were given, respectively. Meanwhile, the boundary between near-field forward scattering and far-field forward scattering was quantitatively defined, which laid the theoretical foundation for the corresponding signal processing algorithms. Finally, with CST simulation results the accuracy of the echo model is verified and impacts of objects' real shapes are analysed. © 2019 Institution of Engineering and technology. All rights reserved.

关键词： Forward scattering

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Dynamic event-triggered cooperative tracking algorithm for high-speed vehicles 4

Dynamic event-triggered cooperative tracking algorithm for h...

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2024 4th International Conference on Mechatronics, Automation and Intelligent Control, MAIC 2024

作者： Chen, Yu Cai, Yuanli Liu, Jiaqi Deng, Yifan Lu, Jing Faculty of Electronic and Information Engineering Xi’an Jiaotong University Shanxi Xi’an China National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing China Shanghai Institute of Satellite Engineering Shanghai China

To address the challenges of single-sensor visual limitations and network congestion in tracking high-speed vehicles, a dynamic event-triggered cooperative cubature Kalman filtering algorithm is proposed. Initially, a dynamic event-triggered mechanism is developed based on measurement state information to reduce bandwidth consumption and enhance system responsiveness. Subsequently, within the framework of the cubature Kalman Filter, the covariance matrix and filtering gain matrix for each sensor’s distributed filter are derived using minimum mean square error approximation techniques. Finally, a cooperative filtering algorithm is designed using a weighted average consensus method and applied to tracking of hypersonic glide vehicles. Simulation results demonstrate that the proposed algorithm achieves higher accuracy compared to existing methods. © 2024 Institute of physics Publishing. All rights reserved.

关键词： Kalman filters

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X-band narrowband high-temperature super-conducting filter with high selectivity

X-band narrowband high-temperature super-conducting filter w...

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IET International Radar Conference 2015

作者： Gao, L. Jiang, Z.Y. Liu, J.Q. Liu, H.Y. Bai, J.L. Xu, F. Li, H. Chen, S.Y. Sun, L. Bian, Y.B. Wang, J. He, Y.S. National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics P.O. Box 9200 Beijing100076 China Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences P.O. Box 603 Beijing100190 China

ISBN: (纸本)9781785610387

This paper presents a development of a narrowband hightemperature superconducting filter with high selectivity. The center frequency of this filter is 8.625 GHz and the 3 dB bandwidth is 156 MHz (a fractional bandwidth of 1.81 %). In order to achieve high band edge steepness, we introduce a 10-resonator quasi-elliptic function response with two pairs of transmission zeros in the cascaded quadruplet coupling structure. The filter was manufactured on a 2-in-diameter 0.5-mm-thick MgO wafer with double-sided YBCO films. The measured results show a midband insertion loss of 0.58 dB and a return loss better than 16 dB. Band edge steepness reaches over 3.82 dB/MHz at both the high and low frequency edges. The 60 dB rectangle ratio is less than 1.19. The out-of-band rejection is over 60 dB at 17.8 MHz from the 3 dB band edge.

关键词： Magnesia

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Deterministic and complete hyperentangled Bell states analysis assisted by frequency and time interval degrees of freedom

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Frontiers of physics 2022年第5期17卷 149-157页

作者： Xin-Jie Zhou Wen-Qiang Liu Hai-Rui Wei Yan-Bei Zheng Fang-Fang Du School of Mathematics and Physics University of Science and Technology BeijingBeijing 100083China Center for Quantum Technology Research and Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurements(MOE) School of PhysicsBeijing Institute of TechnologyBeijing 100081China Science and Technology on Electronic Test and Measurement Laboratory North University of ChinaTaiyuan 030051China

Hyperentangled Bell states analysis(HBSA)is an essential building block for certain hyper-parallel quantum information *** propose a complete and deterministic HBSA scheme encoded in spatial and polarization degrees of freedom(DOFs)of two-photon system assisted by a fixed frequency-based entanglement and a time interval *** parity information the spatial-based and polarization-based hyper-entanglement can be distinguished by the distinct time intervals of the photon pairs,and the phase information can be distinguished by the detection *** with previous schemes,the number of the auxiliary entanglements is reduced from two to one by introducing time interval ***,the additional frequency and time interval DOFs suffer less from the collective channel noise.

关键词： hyperentangled Bell states analysis multiple degrees of freedom time interval

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On the metric resolvent: nonexpansiveness, convergence rates and applications

arXiv

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arXiv 2021年

作者： Xue, Feng National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing100076 China

In this paper, we study the nonexpansive properties of metric resolvent, and present a convergence rate analysis for the associated fixed-point iterations (Banach-Picard and Krasnosel’skii-Mann types). Equipped with a variable metric, we develop the global ergodic and non-ergodic iteration-complexity bounds in terms of both solution distance and objective value. A byproduct of our expositions also extends the proximity operator and Moreau’s decomposition identity to arbitrary variable metric. It is further shown that many classes of the first-order operator splitting algorithms, including alternating direction methods of multipliers, primal-dual hybrid gradient and Bregman iterations, can be expressed by the fixed-point iterations of a simple metric resolvent, and thus, the convergence can be analyzed within this unified *** Codes 68Q25, 47H05, 90C25, 47H09 Copyright © 2021, The Authors. All rights reserved.

关键词： Iterative methods

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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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The Study on Porous Media Phase Change Coupling Heat transfer model in Enclosed Metal Cavity

The Study on Porous Media Phase Change Coupling Heat transfe...

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The 2nd International Conference on Materials science and Engineering technology (MSET 2015)

作者： WU Run-hui LIU Jia-qi LIU Xin REN Ai-min ZHANG Sheng-jun MENG Gang National Key Laboratory of Science and Technology on Test Physics & Numerical Mathematical

This thesis is aimed to the external instantaneous high energy heat source,according to enclosed metal cavity,porous medium in the cavity,porous media can by phase change heat transfer characteristic of variegated medium coupling state target's special requirements in the field of aerospace,it is innovatively to put forward a kind of applicable to simulate sealed coupling target,under the condition of instant high energy heat source excitation,By heat source-metal cavityporous medium—porous medium's phase-changeable phase change process heat-transfer characteristic numerical calculation model-creation approach,in use of the metal cavity,in the porous medium incompressible flow phase transition of working medium's heat energy conservation,momentum conservation and mass conservation principle,it is to establish analysis model of coupled heat transfer characteristics of multiple parts,in order to acquire the full target area of airtight coupling state targets,temperature field,pressure field,velocity field and phase change of phase transition of working medium characteristics change with time and space change numerical value to analog *** study results points out:when the incentive heat source keep constant,the change rule of full target area temperature,pressure flow rate and phase change characteristic parameters is in conformity with theory of heat transfer *** heat transfer model can be popularized and applied to the optimization design of incentive heat source,and comprehensive performance optimization of enclosed coupling state objects.

关键词： Enclosed metal cavity,Porous foam materials,Phase transition working medium,Heat transfer model,numerical modeling

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Moving target modelling and indication in MIMO GEO SAR

Moving target modelling and indication in MIMO GEO SAR

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IET International Radar Conference 2018, IRC 2018

作者： Cui, Chang Liu, Xiangrong Dong, Xichao Hu, Cheng Li, Yuanhao School of Information and Electronics Beijing Institute of Technology Beijing China National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing China Beijing Key Laboratory of Embedded Real-time Information Processing Technology Beijing Institute of Technology Beijing China

Multiple-input multiple-output geosynchronous synthetic aperture radar (MIMO GEO SAR), composed by several mini-satellites in GEO orbits, has more spatial degrees of freedom, which helps to suppress clutter and improves the performance of ground moving target indication (GMTI). However, in order to ensure the satellite safety, the satellite spacing in MIMO GEO SAR is very large. It results in the failure of far-field assumption and causes the moving target defocusing because of the mismatch between the steering vector in far-field sources and the moving target echo. Here, a new signal model based on the near-field sources is first given according to the GEO SAR satellite-ground geometry relationship. Then, considering the phase difference between the different channels, the spatial steering vector is derived and the weight vector for adaptive processing is proposed to suppress clutter and indicate the moving target. Finally, computer simulations are carried out for the validation of the proposed method. © 2019 Institution of Engineering and technology. All rights reserved.

关键词： Synthetic aperture radar

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Relationship Between East Asian Winter Monsoon and Summer Monsoon

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Advances in Atmospheric sciences 2011年第6期28卷 1345-1356页

作者：晏红明杨辉袁媛李崇银 Yunnan Climate Center State Key Laboratory of Numerical Modeling for Atmospheric and Geophysical Fluid Dynamics Institute of Atmospheric PhysicsChinese Academy of Sciences National Climate Center School of Meteorology PLA University of Science and Technology

Using national Centers for Environmental Prediction/national Centre for Atmospheric Research（NCEP/NCAR） reanalysis data and monthly Hadley Center sea surface temperature（SST） data,and selecting a representative East Asian winter monsoon（EAWM） index,this study investigated the relationship between EAWM and East Asian summer monsoon（EASM） using statistical analyses and numerical *** possible mechanisms regarding this relationship were also *** indicate a close relationship between EAWM and EASM：a strong EAWM led to a strong EASM in the following summer,and a weak EAWM led to a weak EASM in the following *** EAWM has persistent impacts on the variation of SST in the tropical Indian Ocean and the South China Sea,and on the equatorial atmospheric thermal anomalies at both lower and upper *** these impacts,the EAWM influences the land-sea thermal contrast in summer and the low-level atmospheric divergence and convergence over the Indo-Pacific *** further affects the meridional monsoon circulation and other features of the *** simulations support the results of diagnostic *** study provides useful information for predicting the EASM by analyzing the variations of preceding EAWM and tropical SST.

关键词： East Asian winter monsoon East Asian summer monsoon interannual variation interaction possible mechanism

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