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IET International Radar Conference 2015

作者： Xia Ai Shengjun Zhang Mingliang Wang Weidong Wang Jiaqi Liu Chengguo Liu Xuemei Liu National Key Laboratory of Science and Technology on Test physics & Numerical Mathematical China

ISBN: (纸本)9781510822023

In this paper, a higher-order shift operater (SO) FDTD scheme with second-order accuracy in time and fourth-order in space has been proposed to accurately model scattering of perfect electronic conductor coated with cloaking structures. Several different electromagnetic parameters of the cloaks are taken into account using SO-FDTD method. numerical results indicate that the proposed method is more accuracy than the traditional method maintaining the same grid size. Scattering of different kinds of simplified cylindrical cloaks including thickness and loss are presented and could be served as further study on this subject.

关键词： Finite difference time domain method Higher-order algorithm Scattering of cloaks

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Multi-feature radar signal modulation recognition based on improved PSO algorithm

Multi-feature radar signal modulation recognition based on i...

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IET International Radar Conference 2018, IRC 2018

作者： Gao, Jing-Peng Shen, Liang-Xi Ye, Fang Wang, Shang-Yue Zhang, Ran College of Information and Communication Engineering Harbin Engineering University Harbin China National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing Institute of Space Long March Vehicle Beijing China

In order to solve the problem that radar emitter signal modulation recognition under low signal-to-noise ratio (SNR) has difficulty in selecting the parameters of the classifier and the problem of low recognition rate caused by the improper selection of features, a multi-feature fusion modulation recognition algorithm based on improved particle swarm optimisation (PSO) algorithm is proposed. Firstly, the algorithm uses Choi-Williams distribution time-frequency analysis to transform the radar signals into time-frequency images, and combines transfer learning and principal component analysis (PCA) to extract the transfer features. Then it extracts the Renyi entropy and AR model coefficients of the signals and combines with the image features to realise multi-feature fusion. Finally, the improved PSO algorithm optimises support vector machine parameters so that population converge quickly. The simulation results show that the recognition rate of this algorithm is 95.3% when the SNR is 0 dB. The number of iterations of this algorithm is small, the signal recognition rate of the system is improved, and the effectiveness of the system is improved by applying PCA. © 2019 Institution of Engineering and technology. All rights reserved.

关键词： Principal component analysis

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A Radar Signal Modulation Recognition Algorithm Based on Multi-branch Fusion Difference 6

A Radar Signal Modulation Recognition Algorithm Based on Mul...

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6th IEEE International Conference on Electronic Information and Communication technology, ICEICT 2023

作者： Jiang, Sisi Gao, Jingpeng Jiang, Zhiye Ye, Fang College of Information and Communication Engineering Harbin Engineering University Harbin China Beijing Institute of Space Long March Vehicle National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing China College of Information and Communication Engineering Harbin Engineering University National Key Laboratory of Underwater Acoustic Technology Harbin China

ISBN: (纸本)9798350399059

The time-frequency images of radar modulation signals are similar at low signal-to-noise ratios, which will lead to lower recognition accuracy. This paper proposes an algorithm based on multi-branch fusion differences to identify radar modulation signals. The algorithm designs a multi-branch fusion differential module based on the attention mechanism and differential thinking, to extract time-frequency image fine-grained features and improve the Convolution Neural Network characterization ability. After that, a dual-branch differential network is proposed by combining vanilla convolution and multi-branch fusion difference module. The network can fuse global and detailed features of time-frequency images, which can achieve radar signal modulation recognition. The simulation results show that the recognition accuracy of the algorithm can reach 93.17% at 0dB. Therefore, the algorithm can obtain high recognition accuracy and has high recognition performance. © 2023 IEEE.

关键词： Convolution

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Supertetragonal BaZrS_(3):A promising perovskite sulphide with giant ferroelectricity and low band gap

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science China(physics,Mechanics & Astronomy) 2024年第8期67卷 126-133页

作者： Menglu Li Sa Zhang Chenhan Liu Xiaotao Zu Liang Qiao Haiyan Xiao School of Physics University of Electronic Science and Technology of ChinaChengdu 611731China College of Mathematics and Physics Chengdu University of TechnologyChengdu 610059China Micro-and Nano-scale Thermal Measurement and Thermal Management Laboratory Ministry of Education Key Laboratory of Numerical Simulation of Large-Scale Complex SystemsSchool of Energy and Mechanical EngineeringNanjing Normal UniversityNanjing 210023China

Over the past century,ferroelectricity has offered exciting opportunities for fundamental research and device ***,most of the discovered excellent ferroelectrics are oxide materials with large band gaps,limiting their potential for optoelectronics *** using first-principles calculations we identify a new narrow-gap ferroelectric beyond oxides,i.e.,ferroelectric perovskite sulphide BaZrS_(3).Under large compressive strains,BaZrS_(3)can be stabilized into a unique supertetragonal phase with an extraordinary polarization of 67.16μC/cm^(2),which is even stronger than that of conventional oxide ***,the supertetragonal BaZrS_(3)exhibits a direct narrow band gap of 1.2 eV and excellent electronic *** on the chemical bonding analysis,we attribute the formation of supertetragonal phase to charge re-ordering in which theπbond overlap along the long〈Zr-S〉bond completely vanishes and the antibonding states of theσbond appear below the Fermi *** work provides a conceptual strategy for designing new ferroelectrics for electronic and photovoltaic applications.

关键词： supertetragonal phase perovskite sulphide ferroelectricity

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A Conservative Lagrangian Scheme for Solving Compressible Fluid Flows with Multiple Internal Energy Equations

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Communications in Computational physics 2012年第10期12卷 1307-1328页

作者： Juan Cheng Chi-Wang Shu Qinghong Zeng National Key Laboratory of Science and Technology on Computational Physics Institute of Applied Physics and Computational MathematicsBeijing 100088China Division of Applied Mathematics Brown UniversityProvidenceRI 02912USA Institute of Applied Physics and Computational Mathematics Beijing 100088China

Lagrangianmethods arewidely used inmany fields formulti-material compressible flow simulations such as in astrophysics and inertial confinement fusion(ICF),due to their distinguished advantage in capturing material interfaces *** some of these applications,multiple internal energy equations such as those for electron,ion and radiation are *** the past decades,several staggeredgrid based Lagrangian schemes have been developed which are designed to solve the internal energy equation *** schemes can be easily extended to solve problems with multiple internal energy *** such schemes are typically not conservative for the total ***,significant progress has been made in developing cell-centered Lagrangian schemes which have several good properties such as conservation for all the conserved variables and easiness for ***,these schemes are commonly designed to solve the Euler equations in the form of the total energy,therefore they cannot be directly applied to the solution of either the single internal energy equation or the multiple internal energy equations without significant *** modifications,if not designed carefully,may lead to the loss of some of the nice properties of the original schemes such as conservation of the total *** this paper,we establish an equivalency relationship between the cell-centered discretizations of the Euler equations in the forms of the total energy and of the internal *** a carefully designed modification in the implementation,the cell-centered Lagrangian scheme can be used to solve the compressible fluid flow with one or multiple internal energy equations and meanwhile it does not lose its total energy conservation *** advantage of this approach is that it can be easily applied to many existing large application codes which are based on the framework of solving multiple internal energy *** two dimensional numerical examp

关键词： Lagrangian scheme conservative cell-centered internal energy equation compressible fluid flow three-temperaturemodel

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Widely tunable single-photon source with high spectral-purity from telecom wavelength to mid-infrared wavelength based on MgO:PPLN

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Chinese physics B 2021年第10期30卷 108-112页

作者： Chang-Wei Sun Yu Sun Jia-Chen Duan Guang-Tai Xue Yi-Chen Liu Liang-Liang Lu Qun-Yong Zhang Yan-Xiao Gong Ping Xu Shi-Ning Zhu National Laboratory of Solid State Microstructures and School of Physics Nanjing UniversityNanjing 210093China Key Laboratory of Optoelectronic Technology of Jiangsu Province School of Physical Science and TechnologyNanjing Normal UniversityNanjing 210023China Faculty of Mathematics and Physics Huaiyin Institute of TechnologyHuaian 223003China

By utilizing the extended phase-matching(EPM)method,we investigate the generation of single photons with high spectral-purity in a magnesium-doped periodically-poled lithium niobate(MgO:PPLN)crystal via the spontaneous parametric down-conversion(SPDC)*** adjusting the temperature and pump wavelength,the wavelength of the single photons can be tuned from telecom to mid-infrared(MIR)wavelengths,for which the spectral-purity can be above 0.95 with high transmission *** experiments,we engineer a MgO:PPLN with poling period of 20.35µm which emits the EPM photon pair centered at 1496.6 nm and 1644.0 nm and carry out the joint spectral intensity(JSI)and Glauber’s second-order self-correlation measurements to characterize the spectral *** results are in good agreement with the numerical *** work may provide a valuable approach for the generation of spectrally pure single photons at a wide range of wavelengths which is competent for various photonic quantum technologies.

关键词： single photons quantum technologies periodically-poled lithium niobate

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Dispersive FDTD scheme with conformal technology for analyzing electromagnetic scattering of inhomogeneous plasma array

Dispersive FDTD scheme with conformal technology for analyzi...

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IET International Radar Conference 2015

作者： Xia Ai Shendong Liu Shengjun Zhang Mingliang Wang Jiaqi Liu Gang Meng Hongchao Zhou National Key Laboratory of Science and Technology on Test physics & Numerical Mathematical China

ISBN: (纸本)9781510822023

In this paper, a dispersive conformal FDTD method have been proposed to accurate model the interface between two adjacent dispersive mediums. The method is based on the technology of area average between two adjacent dispersive interfaces, which is different from existing dispersive conformal FDTD schemes which involve with the interface between free space and dispersive medium. numerical results show the proposed method would enhance the accurate level compared to the staircasing FDTD scheme involved in the inhomogeneous plasma.

关键词： Conformal method FDTD electromagnetic scattering

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A Fast Design Method for Ultra Broadband Absorbers Using RC Equivalent Circuit Model

A Fast Design Method for Ultra Broadband Absorbers Using RC ...

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

作者： Kong, Xianglin Zhao, Lei Wang, Fengjun Zhang, Shengjun Fu, Yixiang Pang, Xiaoyu Liu, Xiaochun Shen, Xiaopeng China University of Mining and Technology School of Information and Control Engineering XuZhou China National Key Laboratory of Science and Technology on Test Physics & Numerical Mathematical Beijing China Key Laboratory of Aeronautical Science and Technology for High Performance Electromagnetic Window Jinan China China University of Mining and Technology School of Materials and Physics Xuzhou China

ISBN: (纸本)9781665452366

An accuracy and efficient approach is proposed to fast design ultra-wideband microwave absorbers. The RC equivalent circuit model of absorbers is established according to impedance matching and transmission line theory. The model is suitable for low and high-frequency absorbers composed of multilayer square high impendence surface (HIS) and air layers of impendence matching. Absorbers with different parameters can be fast designed by utilizing the proposed model and genetic algorithm. The reflection coefficient of RC circuit and full-simulation are in good agreement, both of them are lower than -10 dB within 2-18 GHz or 4-50 GHz (fractional bandwidth of 160% or 170.37%), with the total thickness close to the Rozanov limit. An absorber is fabricated and measured to further verify the accuracy of the model. The measured results have a good agreement with the RC circuit model, which indicates the proposed method is an efficient way for fast designing ultra-broadband thin absorbers using double-layer (or multilayer) square HIS. © 2022 IEEE.

关键词： Multilayers

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A unified back-projection correction algorithm for squint SAR based on SPECAN processing

A unified back-projection correction algorithm for squint SA...

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Signal, Information and Data Processing (ICSIDP), IEEE International Conference on

作者： Chao Wang Heng Sun Xin-Yu Zhang Ran Zhang National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing P.R. China

ISBN: (数字)9781728123455

ISBN: (纸本)9781728123462

The missile-borne or airborne synthetic aperture radar (SAR) usually adopts the squint mode and subaperture to satisfy maneuvering and the real-time processing. A realtime imaging algorithm of squint SAR based on SPECAN processing is presented. It has high computational efficiency in low resolution. A unified back-projection algorithm is proposed to solve the problem of fan-shaped distortion and geometric distortion. Simulation results validate the effectiveness of the proposed method.

关键词：

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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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International Applied Computational Electromagnetics Society Symposium in China

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

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.

ISBN: (纸本)9781509043118

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.

关键词： Artificial structure Electromagnetic lattice Artificial structure lattice theory natural material ELECTROMAGNETIC

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