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45th EPS Conference on Plasma physics, EPS 2018

作者： Wu, Runhui Liu, Jiaqi Meng, Gang Chai, Song Liu, Xin Ren, Aimin Yan, Feng Beijing Institute of Space Long March Vehicle National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing100076 China

ISBN: (纸本)9781510868441

In this paper, the spatial distribution characteristics of electron density are calculated based on the plasma jet diffusion model. The computed results are compared with the results of numerical calculation, validation test results. Researches of the paper are demonstrated that the plasma electron density is attenuated as the approximate exponential with increasing distance from the nozzle exit, the closer distance from the nozzle exit, the greater the attenuation slope, on the far away from the nozzle exit, the electron density attenuation with distance is the flat state. This method is simple and efficient, and it is a good tool to solve engineering calculation problems. © Copyright (2018) by European Physical Society (EPS) All rights reserved.

关键词： Plasma jets

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numerical and feasibility study of onboard MHD power extraction on supersonic vehicle 45

Numerical and feasibility study of onboard MHD power extract...

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45th EPS Conference on Plasma physics, EPS 2018

作者： Chai, Song Meng, Gang Wu, Runhui Liu, Jiaqi Liu, Xin Sun, Ruiqi Beijing Institute of Space Long March Vehicle National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing100076 China

ISBN: (纸本)9781510868441

Within this paper, a concept model containing main features of on-board magnetohydrodynamic (MHD) generators has been constructed and its feasibility of power extraction on supersonic vehicle for a typical flight condition has been studied numerically. The results revealed that the MHD generator is capable of providing substantial energy output up to tens of kilowatts per square meter or even several hundred kilowatts if the alkali-seeded boundary layer has been coated. © Copyright (2018) by European Physical Society (EPS) All rights reserved.

关键词： Magnetohydrodynamic converters

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Compound extreme events and health risks in China: A review

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Atmospheric and Oceanic science Letters 2025年

作者： Tang, Haosu Huang, Gang Hu, Kaiming Wang, Jun Huang, Cunrui Yang, Xianke School of Geography and Planning University of Sheffield Sheffield United Kingdom National Key Laboratory of Earth System Numerical Modeling and Application Institute of Atmospheric Physics Chinese Academy of Sciences Beijing China University of Chinese Academy of Sciences Beijing China The Key Laboratory of Land Surface Pattern and Simulation Institute of Geographical Sciences and Natural Resources Research Chinese Academy of Sciences Beijing China Vanke School of Public Health Tsinghua University Beijing China MARA Key Laboratory of Crop Ecophysiology and Farming System in the Middle Reaches of the Yangtze River College of Plant Science and Technology Huazhong Agricultural University Hubei China

Against the backdrop of global warming, China has been facing increasingly frequent and severe extreme weather and climate events, with a prominent risk of compound extreme events induced by interactions among multiple climate drivers and/or hazards. The present study first reviews the definition and classification of compound extreme events in China. Then, it summarizes research progress on the evolutionary characteristics, formation mechanisms, and future projections of different types of compound extreme events. The potential risks and possible impact pathways of three specific event types—namely, continuous day–night hot extremes, temperature–humidity compound events, and high-temperature–ozone compound events—on the health of the Chinese population are then explored. Finally, a framework for assessing the hazard risk of compound extreme events is constructed, accompanied by response strategies based on carbon neutrality targets. Building on existing research achievements, five future research directions are proposed: (1) identifying the risk chains of compound events;(2) addressing the constraints of observational records and coupled model performances;(3) attributing and understanding the drivers of compound extreme events;(4) finding optimal pathways for carbon reduction and air quality improvement;and (5) promoting inter-disciplinary, multi-regional, and cross-sectoral collaboration. Strengthening research in these directions will deepen our understanding of compound extreme events and provide technological support for climate change adaptation and health risk responses in China. 摘要在全球变暖的背景下, 中国面临着日益频繁和严峻的极端天气气候事件, 其中以多种气候驱动因子和/或灾害相互作用而形成的复合型极端事件风险尤为突出. 本文首先回顾了中国区域复合型极端事件的定义与分型;然后综述了不同类型复合型极端事件的演变特征, 形成机制以及未来预估等方面的研究进展;随后, 探讨了日夜持续型极端高温事件, 温湿复合事件以及高温–臭氧复合事件等三类事件对我国人群健康的潜在风险及可能的影响途径;最后, 阐述了复合型极端事件灾害风险评估框架, 并在此基础上提出了基于碳中和目标的应对策略. 在总结既有研究成果的基础上, 提出了五个未来亟需关注的研究方向: (1)复合事件灾害风险链的识别问题;(2)观测资料和耦合模式性能的制约问题;(3)复合型极端事件的归因与成因问题;(4)碳减排与空气质量改善的最优路径问题;(5)多学科, 多区域, 多部门的合作问题

关键词： Air pollution Carbon neutrality Compound extreme event Extreme weather Global warming Population health

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Dual-Polarized Filtering Antenna for Base Station Application

Dual-Polarized Filtering Antenna for Base Station Applicatio...

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International Conference on Microwave and Millimeter Wave technology Proceedings

作者： Chao Feng Ding Xiu Yin Zhang Zhi Jie Zhang Yun Fei Cao Lu Gao Jun Yang School of Electronic and Information Engineering South China University of Technology Guangzhou China The State Key Laboratory of Millimeter Waves Nanjing China National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing China

In this paper, a broadband dual-polarized filtering dipole is proposed for base station application. Filtering response is obtained by adding simple slits on each arm of the traditional dual polarized dipole antenna. Both lower and upper stopband radiation nulls are generated. The operating bandwidth of the proposed antenna is 1.7-2.9 GHz (52%). The out-of-band suppression level is about 10 dB within 0.69-1.5 GHz and 3.3-3.8 GHz. The simulated port isolation is more than 26 dB. The proposed antenna element is suitable for potential base station applications.

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PolSAR Image Edge Detection via Structure Tensor Analysis

PolSAR Image Edge Detection via Structure Tensor Analysis

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IEEE International Geoscience and Remote Sensing Symposium

作者： Xiangrong Liu Wei Mao Shunsheng Zhang Lei Wu Wen-Qin Wang National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing China Sch. of Info. Comm. Engin. University of Electronic Science and Technology of China Chengdu China

The weighted structure tensor (ST) can be usually used on edge detection of multi-channel images, including polarimetric synthetic aperture radar (polSAR) images. The traditional weighting method is average weighting, each channel considered to provide the same edge information. But in fact different channels tend to contain different amount of edge information, so the traditional weighting method cannot be adopted to extract full edge information of the multi-channel images. This letter proposes a novel weighting method for ST, in which the weight of each channel is obtained by the eigenvalue-measured way. Experimental results show that the proposed method outperforms the traditional method on edge detection.

关键词： Image edge detection Eigenvalues and eigenfunctions Estimation Optical imaging Hyperspectral imaging Corner detection

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Two-Dimensional Imaging With Stationary Nonuniform Frequency Diverse Array Transmitter

Two-Dimensional Imaging With Stationary Nonuniform Frequency...

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IEEE International Geoscience and Remote Sensing Symposium

作者： Xiangrong Liu Wei Mao Lei Wu National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing China Sch. of Info. Comm. Engin. University of Electronic Science and Technology of China Chengdu China

This paper proposes a simple two-dimensional imaging via stationary nonuniform frequency diverse array (FDA) transmitter by exploiting FDA both range and angle dependent transmit beampattern. The nonuniform FDA transmitter only generates range-dependent beampattern, so that two-dimensional (range-angle dimension) imaging of targets can be achieved without the employment of moving radar platform, by jointly utilizing the only range-dependent transmitter beampattern and general single-antenna or phased-array antenna. The effectiveness of the proposed method is verified by simulation results.

关键词： Radar imaging Imaging Frequency diversity Radar antennas Transmitters Radar remote sensing

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Assimilating summer sea ice thickness enhances predictions of Arctic sea ice and surrounding atmosphere within two months

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npj Climate and Atmospheric science 2025年第1期8卷 1-13页

作者： Liu, Anling Yang, Jing Bao, Qing Vitart, Frederic Liu, Jiping Liang, Xi Lu, Mengqian Kim, Seong-Joong Gong, Daoyi Tian, Zhongxiang Liu, Hongbo State Key Laboratory of Earth Surface Processes and Hazards Risk Governance (ESPHR) Faculty of Geographical Science Beijing Normal University Beijing China State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics (LASG) Institute of Atmospheric Physics Chinese Academy of Sciences Beijing China European Centre for Medium-Range Weather Forecasts (ECMWF) Reading United Kingdom School of Atmospheric Sciences Sun Yat-sen University Zhuhai China Key Laboratory of Marine Hazards Forecasting National Marine Environmental Forecasting Center Ministry of Natural Resources Beijing China Department of Civil and Environmental Engineering The Hong Kong University of Science and Technology Hong Kong Otto Poon Centre for Climate Resilience and Sustainability The Hong Kong University of Science and Technology Hong Kong Korea Polar Research Institute Incheon South Korea

Subseasonal prediction of Arctic sea ice and associated atmospheric conditions during the melting season remains challenging due to limited understanding of sea ice initial conditions. This study integrates sea ice assimilation into the coupled model FGOALS-f2 using the localized error subspace transform ensemble Kalman filter, and conducts subseasonal predictions starting from August 1st over 2004–2023. Results show that simultaneous assimilation of sea ice concentration (SIC) and thickness (SIT) significantly improves sea ice predictions for up to two months, while assimilating SIC alone primarily benefits one-month lead predictions. SIT assimilation provides added predictive value for surface air temperature (SAT) forecasts beyond SIC assimilation alone, effectively extending the atmospheric influence of sea ice initial conditions to two months. This improvement in SAT predictions is primarily attributed to a more realistic representation of the surface energy budget. These findings highlight the pivotal role of summer SIT assimilation to enhance subseasonal predictions in the Arctic and challenge the conventional view that initial conditions affect only short-term forecasts. This study underscores the necessity for better representation of ice–atmosphere interactions in models and advocates for enhanced observational capabilities for summer SIT to improve subseasonal predictions in the Arctic and surrounding regions. © The Author(s) 2025.

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An Experimental Study on the Object Shielding Performance of Discrete Metal Wire Array

An Experimental Study on the Object Shielding Performance of...

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2018 IEEE International Conference on Computational Electromagnetics, ICCEM 2018

作者： Wang, Weidong Liu, Xin Wang, Mingliang Liu, Jiaqi Meng, Gang Gao, Zhiyong Mu, Lei Ai, Xia Zhang, Shengjun Li, Jianbing Beijing Institute of Space Long March Vehicle National Key Laboratory of Science and Technology on Test Physics Numerical Mathematical Beijing China College of Electronic Science National University of Defense Technology Changsha China

ISBN: (纸本)9781538612415

In this paper, a method of shielding the object behind a discrete metal wire array is proposed and verified by anechoic chamber experiments. Results show that if the metal wire array is dense enough (cell size is smaller than half of the wavelength), the object behind it can be effectually shielded by the discrete metal wire array. The principle can be applied to electromagnetic camouflage and protection. © 2018 IEEE.

关键词： Electromagnetic shielding

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Sub-seasonal to Seasonal Hindcasts of Stratospheric Sudden Warming by BCC_CSM1.1(m):A Comparison with ECMWF

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Advances in Atmospheric sciences 2019年第5期36卷 479-494页

作者： Jian RAO Rongcai REN Haishan CHEN Xiangwen LIU Yueyue YU Yang YANG Key Laboratory of Meteorological Disaster Ministry of Education/Joint International Research Laboratory of Climate and Environment Change/Collaborative Innovation Center on Forecast and Evaluation of Meteorological DisastersNanjing University of Information Science and Technology State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric Physics Chinese Academy of Sciences Fredy and Nadine Herrmann Institute of Earth Sciences The Hebrew University of Jerusalem Edmond J.Safra Campus Climate Model Division National Climate Center China Meteorological Administration Institute of Urban Meteorology China Meteorological Administration

This study focuses on model predictive skill with respect to stratospheric sudden warming(SSW) events by comparing the hindcast results of BCC_CSM1.1(m) with those of the ECMWF's model under the sub-seasonal to seasonal prediction project of the World Weather Research Program and World Climate Research Program. When the hindcasts are initiated less than two weeks before SSW onset, BCC_CSM and ECMWF show comparable predictive skill in terms of the temporal evolution of the stratospheric circumpolar westerlies and polar temperature up to 30 days after SSW onset. However, with earlier hindcast initialization, the predictive skill of BCC_CSM gradually decreases, and the reproduced maximum circulation anomalies in the hindcasts initiated four weeks before SSW onset replicate only 10% of the circulation anomaly intensities in observations. The earliest successful prediction of the breakdown of the stratospheric polar vortex accompanying SSW onset for BCC_CSM(ECMWF) is the hindcast initiated two(three) weeks earlier. The predictive skills of both models during SSW winters are always higher than that during non-SSW winters, in relation to the successfully captured tropospheric precursors and the associated upward propagation of planetary waves by the model initializations. To narrow the gap in SSW predictive skill between BCC_CSM and ECMWF, ensemble forecasts and error corrections are performed with BCC_CSM. The SSW predictive skill in the ensemble hindcasts and the error corrections are improved compared with the previous control forecasts.

关键词： sub-seasonal to seasonal(S2S)hindcast stratospheric sudden warming BCC_CSM ensemble forecast error correction

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Preface to Special Topic on Atmospheric Greenhouse Gas Measurement and Application in China

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Advances in Atmospheric sciences 2020年第6期37卷 555-556页

作者： Pengfei HAN Ning ZENG Bo YAO Weijian ZHOU Liqi CHEN Shaoqiang WANG Honggang LV Wei XIAO Lingyun ZHU Jiaping XU State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China Department of Atmospheric and Oceanic Science University of MarylandCollege ParkMD 20742USA Meteorological Observation Centre of China Meteorological Administration Beijing 100081China Institute of Earth Environment Chinese Academy of SciencesXi’an 710061China Third Institute of Oceanography Ministry of Natural ResourcesXiamen 361005China Institute of Geographic Sciences and Natural Resources Research Chinese Academy of SciencesBeijing 100101China National Marine Environment Forecasting Center Beijing 100081China Nanjing University of Information Science&Technology Nanjing 210044China Shanxi Institute of Meteorological Sciences Taiyuan 030002China Jiangsu Institute of Meteorological Sciences Nanjing 210009China

China initiated a national carbon trading market in December *** and actions to reduce greenhouse gas(GHG)emissions require consistent,reliable and timely information on GHG *** monitoring and modeling studies provide GHG emission estimates to evaluate and guide progress towards emission *** monitoring has mainly focused on global-scale background networks over the last few decades,while recent efforts have been made on regional and urban scales,such as projects in the Beijing-Tianjin-Hebei city cluster,in Paris,Washington-Baltimore.

关键词： national market city cluster

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