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

作者： Jinliang Bai Peng Qin Hu Li Ran Zhang Xinyu Zhang National key laboratory of science and technology on test physics and numerical mathematics Beijing Institute of Space Long March Vehicle Beijing China

ISBN: (数字)9781728123455

ISBN: (纸本)9781728123462

In this paper, the radar signal is optimized based on the pulse compression repair (PCR) algorithm, which mainly reduces the computational amount to makes it more advantageous to achieve. The main idea is to implement PCR in a parallel way. The method of implementing parallelism is well known, that is, the signal is segmented, and different segmentation methods can be adopted according to different signal models. In this paper, the chirp signal is mainly processed by decimation and segmentation, and some intrinsic benefits of the performance and computational balance of the proposed method are discussed.

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Broadband Dual-Polarized Antenna with Enhanced Front-To-Back Ratio Using Meta-surface

Broadband Dual-Polarized Antenna with Enhanced Front-To-Back...

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Asia-Pacific Conference on Microwave

作者： Pei Zheng Yuwei Qiu Jinliang Bai Ziwei Xu Xin Liu Jiaqi Liu Jun Li Shuo Zhang Hailiang Zhu Gao Wei National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing China Northwestern Polytechnical University Xi'an Shaanxi China

ISBN: (数字)9781728135175

ISBN: (纸本)9781728135182

A novel broadband dual-polarized dipole antenna with enhanced front-to-back ratio is proposed. By placing metasurface around the radiators, the proposed dipole antenna exhibits wide impedance bandwidth (S11&S22 ≤ -12dB) of 52% from 0.675 to 1.15 GHz, covering the lower frequency band (0.69~0.96GHz) of base station antenna. Simulated results show that the front-to-back ratio can be increased by 4-5dB after adding the meta-surface, radiation pattern with enhanced frontto-back ratio (FBR) higher than 20dB were achieved over the operating frequency range. In addition, the antenna architecture is simple and easy to fabricate in base stations that can be used in modern mobile communication systems.

关键词： Dipole antennas Broadband antennas Antenna radiation patterns Probes Broadband communication Bandwidth

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Physical Layer Security of Cooperative Network with Machine Learning-based Relay Selection

Physical Layer Security of Cooperative Network with Machine ...

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IEEE International Symposium on Electromagnetic Compatibility (EMC-Beijing)

作者： Fang Liu Yajuan Wang Hu Li Beijing University of Posts and Telecommunications Beijing China National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing China

ISBN: (数字)9781728144160

ISBN: (纸本)9781728144177

We explore the potential of machine learning for relay selection in a cooperative multi-relay wiretap network with decode-and-forward (DF) protocol, aiming to enhance the physical layer security. Such network is divided into two scenarios according to whether the channel state information (CSI) of wiretap links is available or not for source, when it is assumed that the CSI of the main links has been known at the source. In addition, two machine learning-based schemes, namely, the convolutional neural network(CNN)-based multi-classifier and the support vector machine(SVM)-based multi-classifier, are proposed to characterize the conventional optimization problem of cooperative relay selection as a multi-classification problem in two scenarios mentioned above. In our study, we provide more insight into the spatial correlation of CSI and make the first attempt to introduce the CNN for relay selection in a cooperative multi-relay wiretap network. Finally, the simulation results indicate that two machine learning-based with relatively low selection complexity and less feedback amount achieve substantially the same secrecy performance as the conventional selection scheme.

关键词： Relays Training Machine learning Support vector machines Physical layer security Neurons Correlation

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Influences of different definitions of the winter NAO index on NAO action centers and its relationship with SST

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Atmospheric and Oceanic science Letters 2019年第5期12卷 320-328页

作者： JING Yujie LI Yangchun XU Yongfu FAN Guangzhou School of Atmospheric Sciences ζhengdu University of Information TechnologyChengduChina State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry Institute of Atmospheric PhysicsChinese Academy of SciencesBeijingChina Laboratory for Regional Oceanography and Numerical Modeling Qingdao National Laboratory for Marine Science and TechnologyQingdaoChina Department of Atmospheric Chemistry and Environmental Sciences College of Earth ScienceUniversity of Chinese Academy of SciencesBeijingChina

Winter North Atlantic Oscillation(NAO)indexes from observations based on various winter durations are *** show that there are significant differences in the interannual and decadal variations of these NAO *** the same data source,a different definition of winter duration can lead to different signs of NAO index in some years,which mainly appear to be in the period of decadal phase *** different winter durations induce different cycles of the observation-based *** longer the winter duration,the stronger the decadal *** NAO defined by different winter durations also can generate different descriptions of the NAO action centers,including the position and *** longer the winter duration,the more southerly action centers appear to *** movement of the action centers affects not only site-based NAO indexes but also those defined by other methods,such as empirical orthogonal function(EOF)*** length of time used in EOF analysis has a great influence on the spatial pattern of the NAO mode,which results in a considerable difference between the corresponding NAO *** of which NAO index is used,the NAO-related SST anomalies show the same tripole *** longer the winter duration,the more significant the relationship between the NAO and SST affected by the timescale of sea-air interaction.

关键词： NAO index winter duration period action centers sea surface temperature

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Impact analysis of CFAR detection for false targets generated by the phase-switched screen

Impact analysis of CFAR detection for false targets generate...

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

作者： Ran Zhang Yuan S Chen Yu X Zhang Lei Guo Liang J Bai Ping L Zhang National key laboratory of science and technology on test physics and numerical mathematics Beijing institute of Space Long March Vehicle No. 1 Nanda Hongmen Road of Fengtai District Beijing China National key laboratory of science and technology on test physics and numerical mathematics Beijing institute of Space Long March Vehicle Beijing China

ISBN: (数字)9781728123455

ISBN: (纸本)9781728123462

The phase-switched screen (PSS) has been proved effective in the application of shielding a target or deceiving the radar system when the modulation frequency of it is set greater or smaller than the signal bandwidth. This paper analyses impacts of false targets generated by PSS (PSS-decoys) echoes on radar constant false alarm rate detection. The generation principle of PSS-decoys and the key factors that influence the signatures of PSS-decoys are introduced briefly at first. On base of it, the detection cost caused by the false alarm and false dismissal in a search period of radar is chosen as the criteria of detection performance. The detection costs of CA-CFAR, OS-CFAR, CMLD-CFAR detectors under multiple decoys jamming environment are analysed. Specially, we investigate the influence of the PSS key factors on detection costs from the perspective of simulation. The results show that detection costs will increase remarkably due to false targets existing and it is sensitive to the switching frequency, and the relationship to the duty ratio is tightly relevant to SNR. Among three detectors, the detection costs of CMLD-CFAR detector are higher than that of adopting CA-CFAR and that of adopting OS-CFAR.

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A New Formation Mechanism of Counterstreaming Mass Flows in Filaments and the Doppler Bullseye Pattern in Prominences

arXiv

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arXiv 2025年

作者： Zhou, Chengrui Shen, Yuandeng Xia, Chun Liu, Dongxu Tang, Zehao Yao, Surui Yunnan Observatories Chinese Academy of Sciences Kunming650216 China School of Aerospace Harbin Institute of Technology Shenzhen518055 China Shenzhen Key Laboratory of Numerical Prediction for Space Storm Harbin Institute of Technology Shenzhen518055 China State Key Laboratory of Solar Activity and Space Weather National Space Science Center Chinese Academy of Sciences Beijing100190 China School of Physics and Astronomy Yunnan University Kunming650500 China University of Chinese Academy of Sciences Beijing100049 China

The eruption of solar prominences can eject substantial mass and magnetic field into interplanetary space and cause geomagnetic storms. However, various questions about prominences and their eruption mechanism remain unclear. In particular, what causes the intriguing Doppler bullseye pattern in prominences has not yet been solved, despite some preliminary studies proposing that they are probably associated with counterstreaming mass flows. Previous studies are mainly based on single-angle and short timescale observations, making it difficult to determine the physical origin of Doppler bullseye patterns in prominences. Here, taking advantage of stereoscopic observations taken by the Solar Dynamics Observatory and the Solar Terrestrial Relations Observatory and a three-dimensional numerical simulation, we investigate the origin of prominence Doppler bullseye pattern by tracing a long-lived transequatorial filament/prominence from July 23 to August 4, 2012. We find that repeated coronal jets at one end of the prominence can launch the Doppler bullseye pattern. It is evidenced in our observations and simulation that during the forward traveling of jet plasma along the helical magnetic field structure of the prominence, part of the ejecting plasma can not pass through the apex of the prominence due to the insufficient kinetic energy and therefore forms a backward-moving mass flow along the same or neighboring magnetic field lines. This process finally forms counterstreaming mass flows in on-disk filaments. When the on-disk filament rotates to the solar limb to be a prominence, the counterstreaming mass flows are naturally observed as a Doppler bullseye pattern. Copyright © 2025, The Authors. All rights reserved.

关键词： Plasma magnetohydrodynamic waves

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A Novel Deceptive Jamming Method Via Frequency Diverse Array

A Novel Deceptive Jamming Method Via Frequency Diverse Array

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IEEE International Symposium on Geoscience and Remote Sensing (IGARSS)

作者： Wei Mao Hui Wang Shunsheng Zhang Xiangrong Liu National Key Laboratory of Science and Technology Test Physics and Numerical Mathematics Beijing China Research Institute of Electronic Science and Technology University of Electronic Science and Technology of China Chengdu China

Different from traditional single-element and phased-array antennas, frequency diverse array (FDA) uses a slight frequency offset across the elements to produce angle-, range- and even time-dependent transmit beampattern, which provides promising potentials to develop new jamming techniques on synthetic aperture radar (SAR) imaging. In this paper, we propose a novel deception jamming method against SAR imaging, which uses FDA to quickly generate false targets. Moreover, the position of the false target is controlled by the jammer, and the number of false targets is determined by the number of FDA elements. The proposed methods are validated by extensive simulation results with range-Doppler imaging algorithm.

关键词： Jamming Synthetic aperture radar Imaging Azimuth Interference Radar imaging

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A Physical Layer key Generation method with Reliable Negotiation

A Physical Layer Key Generation method with Reliable Negotia...

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

作者： Yuchen Wang Xuanli Wu Zhicong Xu Wei Wu Hu Li Ran Zhang School of Electronics and Information Engineering Harbin Institude of Technology Harbin China National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing China

ISBN: (数字)9781728123455

ISBN: (纸本)9781728123462

There is a risk of information leakage in the process of wireless communication. The introduction of key generation in the physical layer can effectively improve the security of wireless communication. This paper proposes a new physical layer key generation method in the TDD (time division duplex) communication system. Assume that the uplink and downlink channels are reciprocal. Through LDPC (Low Density Parity Check)channel coding and negotiation algorithm, the inconsistency rate of key generation between Alice and Bob is reduced. Simulation and analysis results show that the method improves the key generation rate and reduces the key inconsistency rate.

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Interannual Salinity Variability in the Tropical Pacific in CMIP5 Simulations

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Advances in Atmospheric sciences 2019年第4期36卷 378-396页

作者： Hai ZHI Rong-Hua ZHANG Pengfei LIN Peng YU College of Atmospheric Sciences Nanjing University of Information Science and TechnologyNanjing 210044China Key Laboratory of Ocean Circulation and Waves Institute of OceanologyChinese Academy of SciencesQingdao 266071China Laboratory for Ocean and Climate Dynamics Qingdao National Laboratory for Marine Science and TechnologyQingdao 266237China University of Chinese Academy of Sciences Beijing 100029China State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics (LASG) Institute of Atmospheric Physics (IAP)Chinese Academy of SciencesBeijing 100029China The Cooperative Institute for Climate and Satellites(CICS) University of MarylandCollege ParkMD 20740USA

Salinity variability and its causes in the tropical Pacific are analyzed using observations, reanalysis products and model simulations. The mixed-layer salinity(MLS) budget analyses from observations and reanalysis products indicate that its interannual evolution is closely related to ENSO and is predominantly governed by surface forcing and surface advection in the western-central equatorial Pacific. It is found that the observed MLS tendency leads Nin?o3.4 by about 12 months due to the effect of negative freshwater flux(evaporation minus precipitation). These observation-based analyses are used to evaluate the corresponding simulation using GFDL-ESM2 M. It is evident that the model can simulate the spatiotemporal variations of MLS with some discrepancies compared to observations. In the warm pool of the equatorial Pacific the MLS tendency in the model is sensitive to ocean dynamics, however model biases cause the tendency to be underestimated. In particular, the freshwater flux is overestimated while the ocean surface zonal current and vertical velocity at the base of the mixed layer are underestimated. Due to model biases in representing the related physics, the effects of surface forcing on the simulated MLS budget are overestimated and those of subsurface and surface advection are relatively weak. Due to weaker surface advection and subsurface forcing than observed, the simulated compensations for surface forcing are suppressed, and the simulated MLS tendency that leads Nin?o3.4 by 8–10 months, which is shorter than the observed lead time. These results are useful for the interpretation of observational analyses and other model simulations in the tropical Pacific.

关键词： mixed-layer salinity salt budget interannual variability tropical Pacific model simulation

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CONDITIONAL NONLINEAR OPTIMAL PERTURBATIONS: APPLICATION IN TROPICAL CYCLONE FORECASTS

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Journal of Tropical Meteorology 2019年第4期25卷 421-436页

作者： TIAN Hong-jun LI Ze-chun WANG Dong-liang WANG Bin Nanjing University of Information Science and Technology Nanjing 210044 China Shanghai Central Meteorological Observatory Shanghai 200030 China National Meteorological Centre Beijing 100081 China Shanghai Typhoon Institute CMAShanghai 200030 China State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric PhysicsChinese Academy of ScienceBeijing 100029 China Ministry of Education Key Laboratory for Earth System Modeling Tsinghua UniversityBeijing 100084 China

Considering the feature of tropical cyclones(TCs) that strong positive vorticity exists in the lower layers of troposphere, this study proposed to use vorticity at 850 hPa as cost function to find the conditional nonlinear optimal perturbation(CNOP), which was largely different from previous studies using total energy of perturbed forecast variables. The CNOP was obtained by an ensemble-based approach. All of the sensitive areas determined by CNOP with vorticity at 850 hPa as cost function for the three cases were located over the TC core region and its vicinity. The impact of the CNOP-based adaptive observations on TC forecasts was evaluated with three cases via observational system simulation experiments(OSSEs). Results showed obvious improvements in TC intensity or track forecasts due to the CNOP-based adaptive observations, which were related to the main error source of the verification area, i.e.,intensity error or location error.

关键词： conditional nonlinear optimal perturbations tropical cyclone intensity track

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