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Broadband Polarization-Conversion Metasurface for a Cassegrain Antenna with High Polarization Purity

Physical Review Applied 2019年第1期12卷 014009-014009页

作者： Wen-Long Guo Guang-Ming Wang Ke Chen Hai-Peng Li Ya-Qiang Zhuang He-Xiu Xu Yijun Feng Air and Missile Defense College Air Force Engineering University Xi’an 710051 China Department of Electronic Engineering School of Electronic Science and Engineering Nanjing University Nanjing 210093 China Science and Technology on Complex Aviation Systems Simulation Laboratory Beijing 100076 China

Polarization conversion has been widely explored in the study of metasurfaces in order to achieve broad operation bandwidths, but its application is still restricted to a few practical scenarios. We design a broadband cross-polarization conversion metasurface and apply it to form a directionally radiated Cassegrain antenna with a low profile and high polarization purity. A quasi-I-shaped meta-atom is first optimized with both high cross-polarization conversion efficiency and a full span of phase modulation in a broad bandwidth. With a hyperbolic phase profile imposed on the surface, a metasurface is engineered that can conduct both focusing and polarization conversion into its cross-polarization component. Then, by introducing a polarized grating as a subreflector and simultaneously fixing the designed metasurface as the main reflector, a planar Cassegrain antenna is facilitated with a low profile, high gain, and high polarization purity in a broad frequency band. This strategy of broad-band polarization conversion and its attempt to design a Cassegrain antenna lays a foundation for high-performance functional devices, promising great potential in real-world applications.

关键词： Metamaterials Polarization of light Radio frequency techniques Devices Wireless communication networks Electromagnetic wave theory Microwave techniques

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Affinity Propagation for Hyperspectral Band Selection 2

Affinity Propagation for Hyperspectral Band Selection

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2018 2nd International Symposium on Resource Exploration and Environmental science, REES 2018

作者： Ren, Zhiwei Wu, Lingda Department of Graduate Management Space Engineering University Beijing101416 China Science and Technology on Complex Electronic System Simulation Laboratory Space Engineering University Beijing101416 China

Because hyperspectral images have the characteristics of high correlation between bands and strong information redundancy, the reduction in dimension of hyperspectral images is an important step in the pre-processing of hyperspectral images. Band selection can preserve the physical meaning of the original data while reducing dimension and has application in many aspects. Affinity Propagation Clustering (AP) is a clustering method proposed by Fray et al. in 2007. AP clusters based on the correlation between data points and treats all data points as potential cluster centers. This paper proposes a band selection method based on AP clustering, which introduces wavelet transform into the calculation of similarity and preference value in clustering algorithm. The dimensionality reduction results are input into the minimum distance classifier for classification, and the classification accuracy was calculated. The dataset is validated by the Indiana Pines dataset. The experimental results verify the effectiveness of the proposed method. © Published under licence by IOP Publishing Ltd.

关键词： Wavelet transforms

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Corrigendum to 'Transition in air pollution, disease burden and health cost in China: A comparative study of long-term and short-term exposure' [Environmental Pollution 277 (2021) Start page 4-End page 4/116770]

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Environmental pollution (Barking, Essex : 1987) 2023年 329卷 121714页

作者： Jun Liu Hao Yin Xiao Tang Tong Zhu Qiang Zhang Zhu Liu XiaoLong Tang HongHong Yi Department of Environmental Engineering School of Energy and Environmental Engineering University of Science and Technology Beijing Beijing 100083 PR China Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants University of Science and Technology Beijing Beijing 100083 PR China Ministry of Education Key Laboratory for Earth System Modeling Department of Earth System Science Tsinghua University Beijing 100084 PR China. Ministry of Education Key Laboratory for Earth System Modeling Department of Earth System Science Tsinghua University Beijing 100084 PR China School of Population and Public Health The University of British Columbia Vancouver BC Canada Energy and Resources Group University of California Berkeley CA USA. State Key Laboratory of Atmospheric Boundary Physics and Atmospheric Chemistry Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 PR China. State Key Joint Laboratory of Environmental Simulation and Pollution Control College of Environmental Sciences and Engineering Peking University Beijing 100871 PR China. Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants University of Science and Technology Beijing Beijing 100083 PR China. Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants University of Science and Technology Beijing Beijing 100083 PR China. Electronic address: yihonghong@***.

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A General Framework for Chinese Domain Knowledge Graph Question Answering Based on TransE

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Journal of Physics: Conference Series 2020年第1期1693卷

作者： Zhongmin Pei Jie Zhang Wei Xiong Li Li Zhangkai Luo Science and Technology on Complex Electronic System Simulation Laboratory Space Engineering University Beijing China Gaojing Network Management and Security Center Beijing China

This paper introduces a general question answering (QA) framework for Chinese domain knowledge graphs to serve various industries. The question is analyzed by shielding invalid characters in this framework, and the TransE calculation of entities and relations is used to search answer, rather than traditional logical queries that rely heavily on predefined rules. In this way, the QA framework can be easily applied to different fields with little manual participation, and reduce the migration cost caused by the lack of scalability of the existing QA systems, which are designed only for specific domains. Then, the proposed framework is operated on the space launch knowledge graph and has achieved HITS@1, HITS@3, HITS@5 scores of 60.60%, 80.87%, 85.61% separately, which is competitive with other restricted domain knowledge graphs. In addition, numerical results on the knowledge graph of the Three Kingdoms and the COVID-19-Character verified the scalability of the QA framework.

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An evaluation method for network communication system efficiency based on multi-source information fusion 37

An evaluation method for network communication system effici...

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37th Chinese Control Conference, CCC 2018

作者： Yuan, Cao Yue-Ping, Wang Xue-Mei, Tang Xiao-Fang, Zhao Science and Technology on Complex Land Systems Simulation Laboratory Beijing100012 China Beijing Institute of Spacecraft System Engineering 100094 China

ISBN: (纸本)9789881563941

The number of experimental data obtained under different conditions is large, and there are some differences in the distribution characteristics of samples. If a large number of different types of data are mixed and the network communication Effectiveness evaluation is carried out, the characteristics of some samples may be drowned out, on the other hand, the information of many experimental samples is not fully utilized. In order to solve this problem, this paper proposes a method of network communication effectiveness evaluation based on multi-source information fusion. This method firstly analyzes the communication success rate of the cell communication node by longitudinal fusion of experimental information. Based on this, the confidence degree is used to construct the weighting coefficient, and the whole communication success rate of the network information system is evaluated by the experiment information of multiple nodes. Thus, the comprehensive evaluation of the communication efficiency of the unit node and the network Information system is realized. © 2018 Technical Committee on Control Theory, Chinese Association of Automation.

关键词： Efficiency

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Dynamic Phase Enabled Topological Mode Steering in Composite Su-Schrieffer-Heeger Waveguide Arrays

arXiv

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arXiv 2024年

作者： Tang, Min Pang, Chi Saggau, Christian N. Dong, Haiyun Lee, Ching Hua Thomale, Ronny Klembt, Sebastian Fulga, Ion Cosma Van Den Brink, Jeroen Vaynzof, Yana Schmidt, Oliver G. Wang, Jiawei Ma, Libo Leibniz Institute for Solid State and Materials Research Dresden Helmholtzstraße 20 Dresden01069 Germany Key Laboratory of Photochemistry Institute of Chemistry Chinese Academy of Sciences Beijing100190 China Department of Physics National University of Singapore Singapore117551 Singapore Institut für Theoretische Physik und Astrophysik Universität Würzburg Würzburg97074 Germany Technische Physik Physikalisches Institut Wilhelm Conrad Roentgen-Research Center for Complex Material System Universität Würzburg Würzburg D-97074 Germany Institute for Theoretical Physics Technische Universität Dresden Dresden01069 Germany Technical University of Dresden Nöthnitzer Str. 61 Dresden01187 Germany TU Chemnitz Chemnitz09126 Germany TU Chemnitz Chemnitz09107 Germany School of Science TU Dresden Dresden01062 Germany School of Electronic and Information Engineering Harbin Institute of Technology Guangdong Shenzhen518055 China

Topological boundary states localize at interfaces whenever the interface implies a change of the associated topological invariant encoded in the geometric phase. The generically present dynamic phase, however, which is energy and time dependent, has been known to be non-universal, and hence not to intertwine with any topological geometric phase. Using the example of topological zero modes in composite Su-Schrieffer-Heeger (c-SSH) waveguide arrays with a central defect, we report on the selective excitation and transition of topological boundary mode based on dynamic phase-steered interferences. Our work thus provides a new knob for the control and manipulation of topological states in composite photonic devices, indicating promising applications where topological modes and their bandwidth can be jointly controlled by the dynamic phase, geometric phase, and wavelength in on-chip topological devices. Copyright © 2024, The Authors. All rights reserved.

关键词： Topology

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Effect of temporal disorder on wave packet dynamics in one-dimensional kicked lattices

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Chinese Physics B 2018年第12期27卷 85-91页

作者： Yuting Wang Yi Gao Peiqing Tong Center for Quantum Transport and Thermal Energy Science School of Physics and TechnologyNanjing Normal UniversityNanjing 210023China jiangsu Key Laboratory on Opto-Electronic Technology School of Physics and TechnologyNanjing Normal UniversityNanjing 210023China Jiangsu Key Laboratory for Numerical Simulation of Large Scale Complex Systems Nanjing Normal UniversityNanjing 210023China

Inspired by the recent experimental progress in noisy kicked rotor systems,we investigate the effect of temporal disorder or quasi-periodicity in one-dimensional kicked lattices with pulsed on-site *** found that,unlike the spatial disorder or quasi-periodicity which usually leads to localization,the effect of the temporal one is more complex and depends on the spatial *** the kicked on-site potential is periodic in real space,then the wave packet will stay diffusive in the presence of temporal disorder or *** the other hand,if the kicked on-site potential is spatially quasi-periodic,then the temporal disorder or quasi-periodicity may lead to a shift of the transition point of the dynamical localization and destroy the dynamical localization in a certain parameter *** results we obtained can be readily tested by experiments and may help us better understand the dynamical localization.

关键词： temporal disorder quasi-periodicity dynamical localization

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Bias Analysis and Correction for Wideband Polarimetric Phased Array Radar

Bias Analysis and Correction for Wideband Polarimetric Phase...

引用

Progress in Electromagnetic Research Symposium (PIERS)

作者： Zhanling Wang Chen Pang Yongzhen Li Xuesong Wang Dou Sun State Key Laboratory of Complex Electromagnetic Environment Effects on Electronics and Information System College of Electronic Science National University of Defense Technology China

ISBN: (数字)9781728134031

ISBN: (纸本)9781728134048

There exhibit some challenges for the wideband fully polarimetric phased array radar (PPAR) in order to meet the requirement for highly accurate polarimetric measurements. Specifically, the electric field radiated from the horizontal (H) port is not necessarily orthogonal to that from the vertical (V ) port when the beam is directed away from the normal of the antenna plane. The cross-polar components are produced, and this is where the polarization biases yield from. Meanwhile, the parameters of electronic equipment, such as transmitter and receiver, are frequency-dependent. The polarimetric characteristics of the practical wideband PPAR antenna vary with frequency, and the polarization non-orthogonality are also frequency-dependent. Therefore, the wideband characteristics and the frequency-dependent polarimetric properties are mutually coupled. All the above factors will cause the polarization measurement bias, and they can also be considered as the frequency response (FR). In this paper, a bias correction method for the wideband PPAR is proposed. Firstly, the fully polarization measurement bias model based on the transmitting and receiving process of the electromagnetic wave is built, and the effects of frequency response on the polarization scattering matrix (PSM) are analyzed. Then, the proposed frequency band division method for measurement parameter bias is detailedly derived to eliminate the effect of the bandwidth. A wideband microstrip patch array element is conducted to demonstrate the effectiveness of the proposed method. The effects of bandwidth and beam direction for the polarimetric variables, such as differential reflectivity (Z DR ) and linear depolarization ratio (L DR ), are analyzed. The simulation results show that the biases of Z DR and L DR can be decreased to less than 0.1dB and -40dB, respectively. The proposed method can maintain a favorable measurement accuracy with widening the frequency band.

关键词： Wideband Frequency measurement Springs Antenna measurements Radar Scattering Frequency response

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A maneuvering penetration strategy via integrated flight/propulsion guidance and control method for air-breathing hypersonic vehicle

A maneuvering penetration strategy via integrated flight/pro...

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2018 IEEE CSAA Guidance, Navigation and Control Conference, CGNCC 2018

作者： Xue, Kong Guodong, Ning Ming, Yang Songyan, Wang Harbin Institute of Technology Control and Simulation Center and Science and Technology Complex System Control and Intelligent Agent Cooperation Laboratory China Beijing Electro-Mechanical Institute China Harbin Institute of Technology Control and Simulation Center China

ISBN: (纸本)9781538611715

Given a maneuvering control strategy for air-breathing hypersonic vehicle, which adopt the compound integrated flight/propulsion guidance and control method, further excavation the capability of scramjet to run stable and low fuel consumption, on this basis, implement accelerate snake maneuver, improve the survival probability of weapons, guarantee the practical application ability of the project. Take one certain type of air-breathing hypersonic vehicle as an example, on the basis of an accurate simulation model, several groups of simulation analysis are carried out, the simulation results show that the method is effective and reliable. © 2018 IEEE.

关键词： Hypersonic vehicles

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Fabrication of highly reliable joint based on Cu/Ni/Sn double-layer powder for high temperature application

Fabrication of highly reliable joint based on Cu/Ni/Sn doubl...

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作者： Xu, Hongyan Shen, Yaochun Hu, Yihua Li, Jianqiang Xu, Ju Beijing Engineering Laboratory of Electrical Drive System and Power Electronic Device Packaging Technology Micro-Nano Fabrication Technology Department Institute of Electronic Engineering Chinese Academy of Sciences Beijing100190 China University of Chinese Academy of Sciences Beijing100049 China School of Electrical Engineering Electronics and Computer Science University of Liverpool Brownlow Hill LiverpoolL69 3GJ United Kingdom State Key Laboratory of Multiphase Complex System Institute of Process Engineering Chinese Academy of Sciences Beijing100190 China

A highly reliable three-dimensional network structure joint was fabricated based on Cu/Ni/Sn powder with double-layer coatings and transient liquid phase bonding (TLPB) technology for high temperature application. The Cu/Ni/Sn joint is characterized by Cu metal particles embedded in the matrix of (Cu,Ni)6Sn5/Ni3Sn4 intermetallic compounds (IMCs), with a low void ratio, and can be reflowed at low temperatures (6Sn5/ Ni3Sn4 IMCs, and the Cu/Ni/Sn joint had a lower void ratio and a higher shear strength than those of Cu/Sn. The mechanism of the Ni-coating layer inhibiting phase transformation was studied. The high reliable three-dimensional network structure joint based on Cu/Ni/Sn double-layer powder was fabricated for high temperature application. Copyright © International Microelectronics Assembly and Packaging Society

关键词： High temperature applications

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