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The Solar Close Observations and Proximity Experiments(SCOPE)mission

Astronomical Techniques and Instruments 2025年第3期2卷 148-174页

作者： Jun Lin Jing Feng Zhenhua Ge Jiang Tian Yuhao Chen Xin Cheng Hui Tian Jiansen He Alexei Pevtsov Haisheng Ji Shangbin Yang ParidaHashim Bin Zhou Yiteng Zhang Shenyi Zhang Xi Lu Yuan Yuan Liu Liu Haoyu Wang Hu Jiang Lei Deng Xingjian Shi Lin Ma Jingxing Wang Shanjie Huang Xiaoshi Zhang Hao Yang Zhonghua Yao He Zhang Yuanming Miao Lei Ni Zhixing Mei Jing Ye Yan Li Yunnan Observatories Chinese Academy of SciencesKunming 650216China University of Chinese Academy of Sciences Beijing 100049China Yunnan Key Laboratory of Solar Physics and Space Science Kunming 650216China Center for Astronomical Mega-Science Chinese Academy of SciencesBeijing 100012China Kunming University of Science and Technology Kunming 650031China Nanjing University Nanjing 210093China Peking University Beijing 100871China National Solar Observatory Boulder 80303USA Purple Mountain Observatories Chinese Academy of SciencesNanjing 210008China National Astronomical Observatories Chinese Academy of SciencesBeijing 100101China School of Astronomy and Space Sciences University of Chinese Academy of SciencesBeijing 100049China Key Laboratory of Solar Activity and Space Weather Beijing 100190China Xinjiang Astronomical Observatory Chinese Academy of SciencesUrumqi 830011China National Space Science Center Chinese Academy of SciencesBeijing 100012China Shanghai Institute of Satellite Engineering Shanghai 201109China Innovation Academy for Microsatellites Chinese Academy of SciencesShanghai 201203China Yunnan University Kunming 650500China Department of Earth Sciences the University of Hong KongHong Kong 999077China Key Laboratory of Earth and Planetary Physics Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100101China Beijing Institute of Spacecraft System Engineering Beijing 100094China

The Solar Close Observations and Proximity Experiments(SCOPE)mission will send a spacecraft into the solar atmosphere at a low altitude of just 5 R☉from the solar *** aims to elucidate the mechanisms behind solar eruptions and coronal heating,and to directly measure the coronal magnetic *** mission will perform in situ measurements of the current sheet between coronal mass ejections and their associated solar flares,and energetic particles produced by either reconnection or fast-mode shocks driven by coronal mass *** will help to resolve the nature of reconnections in current sheets,and energetic particle acceleration *** investigate coronal heating,the mission will observe nano-flares on scales smaller than 70 km in the solar corona and regions smaller than 40 km in the photosphere,where magnetohydrodynamic waves *** study solar wind acceleration mechanisms,the mission will also track the process of ion charge-state freezing in the solar wind.A key achievement will be the observation of the coronal magnetic field at unprecedented proximity to the solar *** polar regions will also be observed at close range,and the inner edge of the solar system dust disk may be identified for the first *** work presents the detailed background,science,and mission concept of SCOPE and discusses how we aim to address the questions mentioned above.

关键词： Solar activities Coronal magnetic field In situ measurements Deep space mission Thermal protection system Thermal-electric conversion

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A high order explicit time finite element method for the acoustic wave equation with discontinuous coefficients

arXiv

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arXiv 2021年

作者： Chen, Zhiming Liu, Yong Xiang, Xueshuang LSEC Institute of Computational Mathematics Academy of Mathematics and System Sciences School of Mathematical Science University of Chinese Academy of Sciences Chinese Academy of Sciences Beijing100190 China Laboratory of Space Technology China Academy of Space Technology Beijing100194 China

In this paper, we propose a novel high order unfitted finite element method on Cartesian meshes for solving the acoustic wave equation with discontinuous coefficients having complex interface geometry. The unfitted finite element method does not require any penalty to achieve optimal convergence. We also introduce a new explicit time discretization method for the ODE system resulting from the spatial discretization of the wave equation. The strong stability and optimal hp-version error estimates both in time and space are established. Numerical examples confirm our theoretical *** Codes 65M12, 65M60 © 2021, CC BY.

关键词： Finite element method

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Fusing Visual and Mobility Data for City Sensing: A Case Study of Urban Village Recognition

SSRN

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SSRN 2023年

作者： Huang, Yingjing Zhang, Fan Gao, Yong Tu, Wei Duarte, Fabio Ratti, Carlo Guo, Diansheng Liu, Yu Hong Kong University of Science and Technology Hong Kong Institute of Remote Sensing and Geographical Information System School of Earth and Space Sciences Peking University Beijing China Senseable City Lab Massachusetts Institute of Technology United States Guangdong Key Laboratory of Urban Informatics Research Institute for Smart Cities Shenzhen Key Laboratory of Spatial Smart Sensing and Services Department of Urban Informatics School of Architecture and Urban Planning Shenzhen University Shenzhen518060 China Tencent Corporation Beijing China

Using multimodal data fusion for city sensing can lead to more accurate, comprehensive and reliable results. Existing studies have used the strategy of fusion of remote sensing and social sensing to make the results least resource-intensive and most accurate. However, it is difficult to distinguish some similar urban functions using only remote sensing to represent visual information in spatial units. To fill the gap, this paper designs Sensing Blender, an end-to-end deep learning model that integrates remote sensing, street view imagery and social sensing to comprehensively characterize urban space. Specifically, this model combines physical environment features from satellite imagery and street view imagery with the dynamic mobility features from taxi trajectory data. In particular, a novel module in Sensing Blender is proposed to extract features from varying numbers of street view images. To validate the performance of the proposed model, a series of experiments of urban village recognition were conducted in Shenzhen, China, with a grid resolution of 500 meters. The results indicate that Sensing Blender achieved good performance with an overall accuracy (OA) of 92.0% and the Kappa of 0.720. Compared with unimodal models, our multimodal model improved the OA by 9.2% and the Kappa by 0.179. The proposed model provides an effective and efficient method for monitoring the distribution of urban villages, potentially supporting urban management, decision-making, and research on urban expansion and urban renewal. © 2023, The Authors. All rights reserved.

关键词： Remote sensing

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An 8-Channel RF Coil based on Microstrip Yagi-antenna for 7T Magnetic Resonance Imaging

An 8-Channel RF Coil based on Microstrip Yagi-antenna for 7T...

引用

IEEE International Symposium on Antennas and Propagation

作者： Ke He Mengxia Yu E Zhao Guiping Li Maoyan Wang Jing Ma School of Physics University of Electronic Science and Technology of China (UESTC) Chengdu China Science and Technology on Special System Simulation Laboratory Beijing China

ISBN: (数字)9781728166704

ISBN: (纸本)9781728166704;9781728166711

A new RF coil based on microstrip Yagi-antenna for 7T magnetic resonance imaging (MRI) is presented in this paper. The RF coil element consists of a driver which is a pair of dipoles printed on the dielectric substrate and two reflectors distributed on either sides of the driver. simulation results show that the proposed 8-channel RF coil array with these elements has high magnetic field intensity and uniform magnetic field distribution in the transverse plane, and can also maintain relatively low specific absorption rate (SAR) in the human body electromagnetic model. In addition, by comparing the RF field distribution of healthy organs and diseased organs, the feasibility of 8-channel RF coil array for human body imaging in MRI system is confirmed.

关键词： Radio frequency Microstrip antenna arrays Magnetic resonance imaging Electromagnetic modeling Specific absorption rate Magnetic fields Microstrip

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Improving the estimation of directional area scattering factor (DASF) from canopy reflectance: theoretical basis and validation

arXiv

引用

arXiv 2022年

作者： Lin, Yi Liu, Siyuan Yan, Lei Yan, Kai Zeng, Yelu Yang, Bin Institute of Remote Sensing and Geographic Information System School of Earth and Space Sciences Peking University Beijing100871 China Guangxi Key Laboratory of Remote Measuring System Guiling University of Aerospace Technology Guilin541004 China School of Land Science and Techniques China University of Geosciences Beijing100083 China College of Land Science and Technology China Agricultural University Beijing100091 China College of Electrical and Information Engineering Hunan University Changsha410082 China

Directional area scattering factor (DASF) is a critical canopy structural parameter for vegetation monitoring. It provides an efficient tool for decoupling of canopy structure and leaf optics from canopy reflectance. Current standard approach to estimate DASF from canopy bidirectional reflectance factor (BRF) is based on the assumption that in the weakly absorbing 710 to 790 nm spectral interval, leaf scattering does not change much with the concentration of dry matter and thus its variation can be neglected. This results in biased estimates of DASF and consequently leads to uncertainty in DASF-related applications. This study proposes a new approach to account for variations in concentrations of this biochemical constituent, which additionally uses the canopy BRF at 2260 nm. In silico analysis of the proposed approach suggests significant increase in accuracy over the standard technique by a relative root mean square error (rRMSE) of 49% and 34% for one- and three dimensional scenes, respectively. When compared with indoor multi-angular hyperspectral measurements reported in literature, the mean absolute error has reduced by 68% for needle leaf and 20% for broadleaf canopies. Thus, the proposed DASF estimation approach outperforms the current one and can be used more reliably in DASF-related applications, such as vegetation monitoring of functional traits, dynamics, and radiation budget. Copyright © 2022, The Authors. All rights reserved.

关键词： Vegetation

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ExpoNAS: Using Exposure-based Candidate Exclusion to Reduce NAS space for Heterogeneous Pipeline of CNNs

ExpoNAS: Using Exposure-based Candidate Exclusion to Reduce ...

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International Conference on Parallel and Distributed systems (ICPADS)

作者： Huijuan Duan Danghui Wang Xingting Zhao Kuizhi Mei Jihe Wang School of Computer Science Northwestern Polytechnical University Xi'an China Engineering Research Center of Embedded System Integration Ministry of Education Northwestern Polytechnical University Xi'an China Institute of Artificial Intelligence and Robotics Xi'an Jiaotong University Xi'an China National Engineering Laboratory for Integrated Aero-Space-Ground-Ocean Big Data Application Technology Northwestern Polytechnical University Xi'an China

Efficiently deploying neural network models on heterogeneous edge systems faces unique challenges. Two major issues are underutilized pipelines caused by hardware heterogeneity and explosive growth of architecture search space. To address these challenges, we propose ExpoNAS, a framework enabling fast deployment-oriented neural architecture search on heterogeneous platforms. ExpoNAS evaluates model partitioning and deployability before search to meet accuracy and latency constraints. However, repeated partitioning leads to exponential growth in architecture search space. We first observe a strong correlation between operational exposure and accuracy improvement, and then we propose an exposure-based reduction technique that excludes the operations of low exposure. By removing these non-critical operations, the exposure-based pruning successfully reduces architecture search time. Our experiments on popular datasets show that the ExpoNAS pipelined design improves execution efficiency by a factor of 2 compared to traditional batch processing. Without compromising accuracy, ExpoNAS is able to reduce the architecture search time by 47.5% for discovering high-accuracy networks, compared to the SOTA NAS strategies.

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Strong controls of daily minimum temperature on the autumn photosynthetic phenology of subtropical vegetation in China

引用

Forest Ecosystems 2021年第3期8卷 413-424页

作者： Peixin Ren Zelin Liu Xiaolu Zhou Changhui Peng Jingfeng Xiao Songhan Wang Xing Li Peng Li College of Geographic Science Hunan Normal UniversityChangsha 410081China Department of Biology Sciences Institute of Environment SciencesUniversity of Quebec at MontrealC.P.8888Succ.Centre-VilleMontreal H3C 3P8Canada Earth Systems Research Center Institute for the Study of EarthOceansand SpaceUniversity of New HampshireDurhamNH 03824USA International Institute for Earth System Sciences Nanjing UniversityNanjing 210023China Jiangsu Provincial Key Laboratory of Geographic Information Technology Key Laboratory for Land Satellite Remote Sensing Applications of Ministry of Natural ResourcesSchool of Geography and Ocean ScienceNanjing UniversityNanjing 210023China

Background:Vegetation phenology research has largely focused on temperate deciduous forests,thus limiting our understanding of the response of evergreen vegetation to climate change in tropical and subtropical ***:Using satellite solar-induced chlorophyll fluorescence(SIF)and MODIS enhanced vegetation index(EVI)data,we applied two methods to evaluate temporal and spatial patterns of the end of the growing season(EGS)in subtropical vegetation in China,and analyze the dependence of EGS on preseason maximum and minimum temperatures as well as cumulative *** results indicated that the averaged EGS derived from the SIF and EVI based on the two methods(dynamic threshold method and derivative method)was later than that derived from gross primary productivity(GPP)based on the eddy covariance technique,and the time-lag for EGSsif and EGSevi was approximately 2 weeks and 4 weeks,*** found that EGS was positively correlated with preseason minimum temperature and cumulative precipitation(accounting for more than 73%and 62%of the study areas,respectively),but negatively correlated with preseason maximum temperature(accounting for more than 59%of the study areas).In addition,EGS was more sensitive to the changes in the preseason minimum temperature than to other climatic factors,and an increase in the preseason minimum temperature significantly delayed the EGS in evergreen forests,shrub and ***:Our results indicated that the SIF outperformed traditional vegetation indices in capturing the autumn photosynthetic phenology of evergreen forest in the subtropical region of *** found that minimum temperature plays a significant role in determining autumn photosynthetic phenology in the study *** findings contribute to improving our understanding of the response of the EGS to climate change in subtropical vegetation of China,and provide a new perspective for accurately evaluating the role played by evergreen vegetatio

关键词： Carbon cycle Evergreen vegetation Plant phenology Solar-induced Fluorescence Climate change MODIS Eddy covariance

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A Type II Radio Burst Driven by a Blowout Jet on the Sun

arXiv

引用

arXiv 2023年

作者： Hou, Zhenyong Tian, Hui Su, Wei Madjarska, Maria S. Chen, Hechao Zheng, Ruisheng Bai, Xianyong Deng, Yuanyong School of Earth and Space Sciences Peking University Beijing100871 China Key Laboratory of Solar Activity and Space Weather National Space Science Center Chinese Academy of Sciences Beijing100190 China National Astronomical Observatories Chinese Academy of Sciences Beijing100011 China TianQin Research Center for Gravitational Physics School of Physics and Astronomy Sun Yat-sen University Zhuhai Campus Zhuhai519082 China Max Planck Institute for Solar System Research Justus-von-Liebig-Weg 3 Göttingen37077 Germany Space Research and Technology Institute Bulgarian Academy of Sciences Acad. Georgy Bonchev Str. Bl. 1 Sofia1113 Bulgaria School of Physics and Astronomy Yunnan University Kunming650050 China School of Space Science and Physics Institute of Space Sciences Shandong University Shandong Weihai264209 China School of Astronomy and Space Science University of Chinese Academy of Sciences Beijing101408 China

Type II radio bursts are often associated with coronal shocks that are typically driven by coronal mass ejections (CMEs) from the Sun. Here, we conduct a case study of a type II radio burst that is associated with a C4.5 class flare and a blowout jet, but without the presence of a CME. The blowout jet is observed near the solar disk center in the extreme-ultraviolet (EUV) passbands with different characteristic temperatures. Its evolution involves an initial phase and an ejection phase with a velocity of 560±87 km s−1. Ahead of the jet front, an EUV wave propagates at a projected velocity of ∼403±84 km s−1 in the initial stage. The moving velocity of the source region of the type II radio burst is estimated to be ∼641 km s−1, which corresponds to the shock velocity against the coronal density gradient. The EUV wave and the type II radio burst are closely related to the ejection of the blowout jet, suggesting that both are likely the manifestation of a coronal shock driven by the ejection of the blowout jet. The type II radio burst likely starts lower than those associated with CMEs. The combination of the velocities of the radio burst and the EUV wave yields a modified shock velocity at ∼757 km s−1. The Alfvén Mach number is in the range of 1.09-1.18, implying that the shock velocity is 10%-20% larger than the local Alfvén velocity. Copyright © 2023, The Authors. All rights reserved.

关键词： Blowouts

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The Medium Energy X-ray telescope (ME) onboard the Insight-HXMT astronomy satellite

引用

science China(Physics,Mechanics & Astronomy) 2020年第4期63卷 35-48页

作者： XueLei Cao WeiChun Jiang Bin Meng WanChang Zhang Tao Luo Sheng Yang ChunLei Zhang YuDong Gu Liang Sun XiaoJing Liu JiaWei Yang Xian Li Ying Tan ShaoZhen Liu YuanYuan Du FangJun Lu YuPeng Xu Ju Guan ShuangNan Zhang HuanYu Wang TiPei Li ChengMo Zhang XiangYang Wen JinLu Qu LiMing Song XiaoBo Li MingYu Ge YuPeng Zhou ShaoLin Xiong Shu Zhang YongJie Zhang ZeHao Cheng Fei Zhang MaoShun Li XiaoHua Liang Min Gao EnBo Yang XiaoHang Liu HongWei Liu YiJung Yang Fan Zhang Key Laboratory of Particle Astrophysics Institute of High Energy PhysicsChinese Academy of SciencesBeijing 100049China Department of Engineering Physics Tsinghua UniversityBeijing 100084China Beijing Key Laboratory of Space Thermal Control Technology Beijing Institute of Spacecraft System EngineeringBeijing 100094China Department of Modern Physics School of Physical SciencesUniversity of Science and Technology of ChinaHefei 230022China School of Physical Sciences Guizhou UniversityGuivang 550025China School of Opto-Electronic Information Science and Technology Yantai UniversityYantai 264005China University of Chinese Academy of Sciences Beijing 100049China

The Medium Energy X-ray telescope(ME) is one of the three main telescopes on board the Insight hard X-ray modulation telescope(Insight-HXMT) astronomy satellite. ME contains 1728 pixels of Si-PIN detectors sensitive in 5-30 ke V with a total geometrical area of 952 cm^2. The application specific integrated circuit(ASIC) chip, VA32TA6, is used to achieve low power consumption and low readout noise. The collimators define three kinds of field of views(FOVs) for the telescope, 1°×4°, 4°×4°,and blocked ones. Combination of such FOVs can be used to estimate the in-orbit X-ray and particle background *** energy resolution of ME is ~3 ke V at 17.8 ke V(FWHM) and the time resolution is 255 μs. In this paper, we introduce the design and performance of ME.

关键词： Si-PIN ASIC medium energy X-ray

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Large-Scale Single Tree Information Extraction of Oil Palm in Malaysia Based on Sub-Meter Visible Light Satellite Images

SSRN

引用

SSRN 2024年

作者： Zhang, Sen Li, Nan Cui, Yaoping Dong, Jinwei Yu, Le Ran, Lishan Chen, Ziyue Niu, Jiqiang Yan, Wei Kanniah, Kasturi Devi Xiao, Xiangming Zhang, Yongguang Key Laboratory of Geospatial Technology for the Middle and Lower Yellow River Regions Henan University Ministry of Education Kaifeng475004 China College of Geography and Environmental Science Henan University Kaifeng475004 China Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application International Institute for Earth System Sciences Nanjing University Nanjing210023 China Key Laboratory of Land Surface Pattern and Simulation Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing100101 China Department of Earth System Science Ministry of Education Key Laboratory for Earth System Modeling Institute for Global Change Studies Tsinghua University Beijing100084 China Department of Geography The University of Hong Kong Pokfulam999077 Hong Kong State Key Laboratory of Earth Surface Processes and Resource Ecology College of Global Change and Earth System Science Beijing Normal University Beijing100875 China College of Geographic Sciences Xinyang Normal University Xinyang464000 China Department of Geoinformation Faculty of Built Environment & Surveying Universiti Teknologi Malaysia Johor Bahru81310 Malaysia Department of Microbiology and Plant Biology Center for Spatial Analysis University of Oklahoma NormanOK73019 United States College of Environment and Planning Faculty of Geoinformation and Real Estate

The distribution of specific tree species and single tree information can shift down the research scale of geography and ecology, bridging research from regional to local scales. However, efficiently and finely extracting the spatial distribution and single tree information for a tree species regionally has always been a challenge due to the constraints of data and algorithms. With sub-meter visible light satellite images (RGB bands) in 2021 to 2022, we constructed a novel method for extracting the spatial distribution and single tree information of oil palm across Malaysia, namely the Single Tree Extraction Method - Oil Palm (STEM-OP). We developed a graphic morphological algorithm based on gradient difference window detection to extract the spatial distribution of oil palms. Then, we proposed an algorithm of double ring sliding detection algorithm to identify the canopy texture features of single oil palm. Finally, an adaptive iterative erosion algorithm was employed to separate overlapping and adjacent canopies into single trees. The overall accuracy of both the spatial distribution and number of single oil palm extracted by STEM-OP exceeded 90%. Our study revealed that the total area of oil palm in Malaysia was 5.25 million hectares, with a total of 572.6 million trees and an average planting density of 109 palms per hectare. The STEM-OP addresses the computational inefficiencies of methods with training samples and limitations of satellite image bands. For the first time, our study extracts the refined spatial distribution of oil palm and obtains the planting density and single tree position on a national scale. All of these are of great value to the formulation of oil palm development policies and ecological protection measures. © 2024, The Authors. All rights reserved.

关键词： Morphology

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