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SSRN 2024年

作者： Kim, Hyeonmin Park, Rokjin J. Hong, Song-You Park, Do-Hyeon Kim, Sang-Woo Oak, Yujin J. Feng, Xu Lin, Haipeng Fu, Tzung-May School of Earth and Environmental Sciences Seoul National University Seoul Korea Republic of Cooperative Institute for Research in Environmental Sciences University of Colorado Boulder United States Physical Sciences Laboratory The National Oceanic and Atmospheric Administration Earth System Research Laboratories Boulder United States Center for Sustainable Environment Research Korea Institute of Science and Technology Seoul Korea Republic of John A. Paulson School of Engineering and Applied Sciences Harvard University CambridgeMA United States State Environmental Protection Key Laboratory of Integrated Surface Water-Groundwater Pollution Control School of Environmental Science and Engineering Southern University of Science and Technology Guangdong Shenzhen China Shenzhen Institute of Sustainable Development Southern University of Science and Technology Guangdong Shenzhen China Seoul National University Korea Republic of

Vertical mixing within the planetary boundary layer (PBL) is crucial for determining surface-level pollutant concentrations. However, standard PBL schemes in chemical transport models (CTMs) often fail to adequately define the upper bounds of vertical mixing, particularly at night. This limitation frequently results in overestimated nocturnal concentrations of pollutants near the surface. To address this issue, we propose a parameterization of mixed layer height (MLH) derived from the Yonsei University (YSU) PBL scheme and thoroughly evaluate it by comparing simulations with various observations. We utilized the Weather research and Forecasting model coupled with GEOS-Chem (WRF-GC) to simulate gas and aerosol distributions over South Korea during the Satellite Integrated Joint Monitoring of Air Quality (SIJAQ) campaign in 2021. The WRF-GC simulations incorporating the MLH parameterization improved the excessive titration of O3 and the overproduction of HNO3 and NO3- in the model. Consequently, the model performances in gaseous and aerosol simulations showed a better agreement with observations, with changes in normalized mean biases (NMBs) of NOX (from 50% to -27%), O3 (from -49% to -28%), NO3- (from 126% to 91%), NH4+ (from 113% to 85%), BC (from 322% to 135%), and PM2.5 (from 58% to 28%). © 2024, The Authors. All rights reserved.

关键词： Atmospheric chemistry

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INTRODUCTION

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Bulletin of the American Meteorological Society 2024年第8期105卷 S1-S11页

作者： Boyer, T. Blunden, J. Dunn, R.J.H. NOAA/NESDIS National Centers for Environmental Information Silver Spring Maryland NOAA/NESDIS National Centers for Environmental Information Asheville North Carolina Met Office Hadley Centre Exeter United Kingdom European Centre for Medium-Range Weather Forecasts Reading United Kingdom University of Maryland College Park Maryland Scripps Institution of Oceanography University of California San Diego La Jolla California NOAA/NWS National Centers for Environmental Prediction Climate Prediction Center College Park Maryland Brandenburg University of Technology (BTU) Cottbus-Senftenberg Germany Servicio Meteorológico Nacional Buenos Aires Argentina NOAA/OAR Physical Sciences Laboratory Boulder Colorado European Centre for Medium-Range Weather Forecasts Bonn Germany Center for Geophysical Research and School of Physics University of Costa Rica San José Costa Rica Department of Meteorology and National Centre for Earth Observation University of Reading Reading United Kingdom Centro Nacional de Monitoramento e Alertas de Desastres Naturais CEMADEN São Paulo Brazil Université Grenoble Alpes Institut des Géosciences de l’Environnement IRD CNRS Grenoble INP Grenoble France Hampton University Hampton Virginia Seychelles Meteorological Authority Mahe Seychelles Section for Glaciers Ice and Snow Norwegian Water Resources and Energy Directorate Oslo Norway National Research Institute for Agriculture Food and Environment (INRAE) CARRTEL Université Savoie Mont Blanc Thonon les Bains France Graduate School of Agriculture Osaka Metropolitan University Sakai Japan Science Faculty Universidad Nacional de Colombia Bogotá Colombia University of Bremen Bremen Germany NOAA Global Monitoring Laboratory Boulder Colorado Servicio Nacional de Meteorología e Hidrología del Perú Lima Perú Centro de Investigaciones sobre Desertificación – Spanish National Research Council (CSIC-UV-GVA) Valencia Spain Hydro-Climate Extremes Lab (H-CEL) Ghent University Ghent Belgium Department o

In 2023, La Niña conditions that generally prevailed in the eastern Pacific Ocean from mid-2020 into early 2023 gave way to a strong El Niño by October. Atmospheric concentrations of Earth’s major greenhouse gases—carbon dioxide, methane, and nitrous oxide—all increased to record-high levels. The annual global average carbon dioxide concentration in the atmosphere rose to 419.3±0.1 ppm, which is 50% greater than the pre-industrial level. The growth from 2022 to 2023 was 2.8 ppm, the fourth highest in the record since the 1960s. The combined short-term effects of El Niño and the long-term effects of increasing levels of heat-trapping gases in the atmosphere contributed to new records for many essential climate variables reported here. The annual global temperature across land and oceans was the highest in records dating as far back as 1850, with the last seven months (June–December) having each been record warm. Over land, the globally averaged temperature was also record high. Dozens of countries reported record or near-record warmth for the year, including China and continental Europe as a whole (warmest on record), India and Russia (second warmest), and Canada (third warmest). Intense and widespread heatwaves were reported around the world. In Vietnam, an all-time national maximum temperature record of 44.2°C was observed at Tuong Duong on 7 May, surpassing the previous record of 43.4°C at Huong Khe on 20 April 2019. In Brazil, the air temperature reached 44.8°C in Araçuaí in Minas Gerais on 20 November, potentially a new national record and 12.8°C above normal. The effect of rising temperatures was apparent in the cryosphere, where snow cover extent by June 2023 was the smallest in the 56-year record for North America and seventh smallest for the Northern Hemisphere overall. Heatwaves contributed to the greatest average mass balance loss for Alpine glaciers around the world since the start of the record in 1970. Due to rapid volume loss beginning in 2021, St. A

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Channel Characterization for the mmWave Vehicle-to-Vehicle Communication in the See-through situation

Channel Characterization for the mmWave Vehicle-to-Vehicle C...

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International Symposium on Antennas, Propagation and EM Theory (ISAPE)

作者： Dong Yan Ke Guan Danping He Junhyeong Kim Heesang Chung Bo Ai Zhangdui Zhong State Key Laboratory of Rail Traffic Control and Safety Beijing Jiaotong University Beijing China Frontiers Science Center for Smart High-speed Railway System Beijing China Moving Wireless Network Research Section Electronics and Telecommunications Research Institute South Korea Beijing Engineering Research Center of High-speed Railway Broadband Mobile Communications Beijing China

ISBN: (纸本)9781665418133

Millimeter-wave (mmWave) is crucial autonomous driving for its wide bandwidth and low I complex vehicular communication scenarios, the shad of large vehicles has a significant influence on th to-vehicle (V2V) channel. Thus, it is necessary to channel characteristics in this case. This paper uses a ray-tracing simulator to research the influence of the and the beam switching technology on the V2V c the “See-Through situation”. Finally, through the ext channel parameters, the characteristics of the V2V (the mmWave band are explored. Conclusions can project ideas for the design of the vehicular communication li

关键词： Antenna theory Millimeter wave technology Vehicular ad hoc networks Switches Bandwidth Ray tracing Millimeter wave communication

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Uplink Precoding Design for Cell-Free Massive MIMO with Iteratively Weighted MMSE

arXiv

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arXiv 2023年

作者： Wang, Zhe Zhang, Jiayi Ngo, Hien Quoc Ai, Bo Debbah, Mérouane The School of Electronic and Information Engineering Beijing Jiaotong University Beijing100044 China The Frontiers Science Center for Smart High-speed Railway System Beijing Jiaotong University Beijing100044 China The Institute of Electronics Communications and Information Technology Queen’s University BelfastBT3 9DT United Kingdom The State Key Laboratory of Rail Traffic Control and Safety Beijing Jiaotong University Beijing100044 China Frontiers Science Center for Smart High-Speed Railway System The Henan Joint International Research Laboratory of Intelligent Networking and Data Analysis Zhengzhou University Zhengzhou450001 China The Research Center of Networks and Communications Peng Cheng Laboratory Shenzhen518066 China The Technology Innovation Institute Abu Dhabi United Arab Emirates CentraleSupélec University Paris-Saclay Gif-sur-Yvette91192 France

In this paper, we investigate a cell-free massive multiple-input multiple-output system with both access points and user equipments equipped with multiple antennas over the Weichselberger Rayleigh fading channel. We study the uplink spectral efficiency (SE) for the fully centralized processing scheme and large-scale fading decoding (LSFD) scheme. To further improve the SE performance, we design the uplink precoding schemes based on the weighted sum SE maximization. Since the weighted sum SE maximization problem is not jointly over all optimization variables, two efficient uplink precoding schemes based on Iteratively Weighted sum-Minimum Mean Square Error (I-WMMSE) algorithms, which rely on the iterative minimization of weighted MSE, are proposed for two processing schemes investigated. Furthermore, with maximum ratio combining applied in the LSFD scheme, we derive novel closed-form achievable SE expressions and optimal precoding schemes. numerical results validate the proposed results and show that the I-WMMSE precoding schemes can achieve excellent sum SE performance with a large number of UE antennas. Copyright © 2023, The Authors. All rights reserved.

关键词： MIMO systems

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Photo-Based Monitoring of Particulate Matter in the Campus: A New Strategy for Student Health

Photo-Based Monitoring of Particulate Matter in the Campus: ...

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2020 International Conference on Green Energy, Environment and Sustainable Development, GEESD 2020

作者： Zhang, Yonghui Gu, Ke Xia, Zhifang Qiao, Junfei Faculty of Information Technology Beijing University of Technology Beijing100124 China Engineering Research Center of Intelligent Perception and Autonomous Control Ministry of Education Beijing100124 China Beijing Key Laboratory of Computational Intelligence and Intelligent System Beijing100124 China Beijing Artificial Intelligence Institute Beijing100124 China State Information Center Beijing100045 China

It is imperative for the students' future health to ensure the students in good physical levels. Recent years have witnessed the increasingly serious harm to student health caused by the continually growing concentration of Particulate Matters (PMs). Consequently, the task of preventing and controlling PM concentrations in the campus is eagerly required. A well-designed model for the monitoring of PM (as the basis for PM prevention and control) has posed a big challenge. Prior works have revealed that photo-based methods are available for the monitoring of PM. Towards validating the effectiveness of existing methods for PM monitoring in the campus, we construct a novel dataset that involves 1,500 photos collected in the Beijing University of Technology. Results confirm that stated-of-the-art methods are far from ideal for the monitoring of PM in the campus. To solve the aforesaid issue, this paper further proposes a novel photo-based PM monitoring model by using the weighted average method solved by LASSO regression to fuse the above methods' outputs tested to infer the PM values. Results demonstrate the superiority of our proposed model as compared to state-of-the-art methods on the large-scale AQPDBJUT dataset. © Published under licence by IOP Publishing Ltd.

关键词： Students

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Fabrication and Mechanical Testing of Ultralight Folded Lattice-CoreSandwich Cylinders

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engineering 2020年第2期6卷 196-204页

作者： Wanxin Li Qing Zheng Hualin Fan Bin Ji State Key Laboratory for Disaster Prevention and Mitigation of Explosion and Impact Army Engineering University of PLANanjing 210007China Research Center of Lightweight Structures and Intelligent Manufacturing State Key Laboratory of Mechanics and Control of Mechanical StructuresNanjing University of Aeronautics and AstronauticsNanjing 210016China Aerospace System Engineering Shanghai Shanghai 2011089China

In this research,two novel folded lattice-core sandwich cylinders were designed,manufactured,and *** lattice core has periodic zigzag corrugations,whose ridges and valleys are directed axially or *** vibration and axial compression experiments were performed to reveal the fundamental frequency,free vibration modes,bearing capacity,and failure mode of the cylinder.A folded lattice core effectively restricts local buckling by reducing the dimension of the local skin periodic cell,and improves the global buckling resistance by enhancing the shear stiffness of the sandwich *** cylinders fail at the mode of material failure and possess excellent load-carrying *** axially directed folded sandwich cylinder has greater load-carrying capacity,while a circumferentially directed folded sandwich cylinder has higher fundamental *** two types of folded lattices provide a selection for engineers when designing a sandwich cylinder requiring strength or *** research also presents a feasible way to fabricate a large-dimensional folded structure and promote its engineering application.

关键词： Folded lattice-core sandwich cylinder Fabrication Mechanical testing

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Evaluation and Uncertainty Analysis of Himawari-8 Hourly Aerosol Product Version 3.1 and its Influence on Surface Solar Radiation Before and During the COVID-19 Outbreak

SSRN

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SSRN 2023年

作者： Tang, Chenqian Shia, Chong Husi, Letu Ma, Run Yoshida, Mayumi Kikuchi, Maki Xu, Jian Li, Nan Zhao, Mengjie Chen, Liangfu Shi, Guangyu State Key Laboratory of Remote Sensing Science Aerospace Information Research Institute Chinese Academy of Sciences Beijing100101 China Nanjing University of Information Science & Technology Nanjing210044 China Remote Sensing Technology Center of Japan Tsukuba305-8505 Japan Japan Aerospace Exploration Agency Tsukuba305-8505 Japan National Space Science Center Chinese Academy of Sciences Beijing100190 China Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control Jiangsu Collaborative Innovation Center of Atmospheric Environment and Equipment Technology School of Environmental Science and Engineering Nanjing University of Information Science & Technology Nanjing210044 China Institute of Tibetan Plateau Research Chinese Academy of Sciences Beijing100101 China State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric Physics Chinese Academy of Sciences Beijing100029 China University of Chinese Academy of Sciences Beijing100049 China

The hourly Himawari-8 version 3.1 (V31) aerosol product has been released and incorporates an updated Level 2 algorithm that uses forecast data as an a priori estimate. However, there has not been a thorough evaluation of V31 data across a full-disk scan, and V31 has yet to be applied in the analysis of its influence on surface solar radiation (SSR). This study firstly investigates the accuracy of V31 aerosol products, which includes three categories of aerosol optical depth (AOD) (AODMean, AODPure, and AODMerged) as well as the corresponding Ångström exponent (AE), using ground-based measurements from the AERONET and SKYNET. Results indicate that V31 AOD products are more consistent with ground-based measurements compared to previous products (V30). The highest correlation and lowest error were seen in the AODMerged, with a correlation coefficient of 0.8335 and minimal root mean square error of 0.1919. In contrast, the AEMerged shows a larger discrepancy with measurements unlike the AEMean and AEPure. Error analysis reveals that V31 AODMerged has generally stable accuracy across various ground types and geometrical observation angles, however, there are higher uncertainties in areas with high aerosol loading, particularly for fine aerosols. The temporal analysis shows that V31 AODMerged performs better compared to V30, particularly in the afternoon. Finally, the impacts of aerosols on SSR based on the V31 AODMerged are investigated through the development of a sophisticated SSR estimation algorithm in the clear sky. Results demonstrate that the estimated SSR is significant consistency with those of well-known CERES products, with preservation of 20 times higher spatial resolution. The spatial analysis reveals a significant reduction of AOD in the North China Plain before and during the COVID-19 outbreak, resulting in an average 24.57 W m–2 variation of the surface shortwave radiative forcing in clear sky daytime. © 2023, The Authors. All rights reserved.

关键词： COVID-19

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Toward a sustainable grassland ecosystem worldwide

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The Innovation 2022年第4期3卷 15-16页

作者： Jian Sun Yi Wang Shilong Piao Miao Liu Guodong Han Junran Li Eryuan Liang Tien Ming Lee Guohua Liu Andreas Wilkes Shiliang Liu Wenwu Zhao Huakun Zhou Mesenbet Yibeltal Mulatu Liyew Berihun Dawn Browning Ayele Almaw Fenta Atsushi Tsunekawa Joel Brown Walter Willms Mitsuru Tsubo State Key Laboratory of Earth System Resources and Environment of Tibetan Plateau Institute of Tibetan Plateau ResearchChinese Academy of SciencesBeijing 100101China School of Life Sciences and School of Ecology State Key Lab of Biological ControlSun Yat-sen UniversityGuangzhou 510275China Sino-French Institute for Earth System Science College of Urban and Environmental SciencesPeking UniversityBeijing 100871China College of Grassland Science and Technology China Agricultural UniversityBeijing 100193China Key Laboratory of Grassland Resources of the Ministry of Education College of GrasslandResources and EnvironmentInner Mongolia Agricultural UniversityHohhot 010011China Department of Geosciences The University of TulsaTulsaOK 74137USA State Key Laboratory of Urban and Regional Ecology Research Center for Eco-Environmental SciencesChinese Academy of SciencesBeijing 100085China Values for Development Ltd Bury St.Edmunds IP333EQUK School of Environment Beijing Normal UniversityBeijing 100875China Faculty of Geographical Science Beijing Normal UniversityBeijing 100875China Key Laboratory of Restoration Ecology for Cold Regions in Qinghai Northwest Institute of Plateau BiologyChinese Academy of SciencesXining 810008China Faculty of Civil and Water Resource Engineering Bahir Dar Institute of TechnologyBahir Dar UniversityBahir DarEthiopia Arid Land Research Center Tottori UniversityTottori 6800001Japan USDA–ARS Jornada Experimental Range Las CrucesNM 88003USA USDA NRCS Jornada Experimental RangeNew Mexico State UniversityMSC 3JERPO Box 30003Las CrucesNMUSA Agriculture and Agri-Food Canada Lethbridge Research Centre54031st Avenue SouthLethbridgeABCanada

Globally,grasslands,covering about 40%of the Earth’s land area,are vital for supporting important ecosystem functions,services,and livelihoods of millions of ***,grassland degradation is a major threat to the maintenance of ecological services,1 food security,and sustainable development,and directly hinders the global efforts with meeting goals and targets such as the The UN Decade on Ecosystem Restoration and Sustainable Development Goals(SDGs).Remote sensing approaches have the advantages of spanning large geographical areas withmultiple spatial,spectral,and temporal *** global scale,remote sensing methods used normalized difference vegetation index to determine net primary productivity(NPP),which still is the effectivemethod to indicate grassland *** master the general situation of grassland,we analyzed the global spatial-temporal variation of NPP from 2001 to 2019 at the pixel level across the *** presented in Figure 1A,the NPP values of global grasslands showed an obvious variation trend,which indicated a considerable distribution pattern of spatial *** decreasing and increasing trend in grassland NPP covered approximately 25.3%and 74.5%of the total grassland area,respectively.

关键词： grassland Figure hinder

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Arbitrarily shaped retro-reflector by optics surface transformation

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Chinese Optics Letters 2020年第10期18卷 58-62页

作者： Fei Sun Yichao Liu Yibiao Yang Zhihui Chen Sailing He Key Laboratory of Advanced Transducers and Intelligent Control System Ministry of Education and Shanxi ProvinceCollege of Physics and OptoelectronicsTaiyuan University of TechnologyTaiyuan 030024China Centre for Optical and Electromagnetic Research State Key Laboratory of Modern Optical InstrumentationNational Engineering Research Center for Optical InstrumentsZhejiang UniversityHangzhou 310058China

A novel way to design arbitrarily shaped retro-reflectors by optics surface transformation is proposed. The entire design process consists of filling an optic-null medium between the input and output surfaces of the retroreflector, on which the points have 180 deg reverse corresponding relations. The retro-reflector can be designed to be very thin(a planar structure) with high efficiency. The effective working angles of our retro-reflector are very large(from-80 deg to +80 deg), which can, in principle, be further extended. Layered metal plates and zero refractive index materials are designed to realize the proposed retro-reflector for a TM polarized beam.

关键词： retro-reflector optics surface transformation

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research on the Segmentation and Extraction of Scenes Along Railway Lines Based on Remote Sensing Images of UAVs 4th

Research on the Segmentation and Extraction of Scenes Along ...

引用

4th International Conference on Electrical and Information Technologies for Rail Transportation, EITRT 2019

作者： Tong, Lei Jia, Limin Wang, Zhipeng Wu, Yunpeng Wang, Ning State Key Laboratory of Rail Traffic Control and Safety Beijing Jiaotong University Beijing China National Engineering Laboratory for System Safety and Operation Assurance of Urban Rail Transit Beijing Jiaotong University Guangdong China Beijing Research Center of Urban Traffic Information Sensing and Service Technologies Beijing Jiaotong University Beijing China

ISBN: (纸本)9789811528651

At present, the manual inspection along railway lines is still a major method to ensure railway operation safely, but the cost is high and work efficiency is low. Therefore, unmanned aerial vehicles (UAVs) patrol inspection is required. This paper presents the effective segmentation of scenes along railway lines (SRL) from remote sensing perspective of UAVs based on the full convolutional networks (FCN). Firstly, the datasets needed in this research are collected and produced from Langfang section of the Beijing–Shanghai high-speed railway. The datasets are expanded by using data augmentation to constrain the overfitting in the training process. Secondly, the segmentation model FCN-8s for SRL is developed and trained. The related setting and hardware environment in the training process are described in this paper. The experimental results show that a single image prediction needs 151.2 ms, to achieve 6.6 fps when input size is 384 × 384. Good accuracy is obtained on the test dataset, i.e., 55.8% MIoU and 70.2% MPA, which meets the expectations of FCN. At the same time, it is also found that the segmentation of railway area achieves the best result thus the railway area is extracted accordingly. © Springer Nature Singapore Pte Ltd. 2020.

关键词： Remote sensing

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