检索结果-内蒙古大学图书馆

International Applied Computational Electromagnetics Society Symposium (ACES)

作者： Ying Zhang Wei Xiong Xichao Dong Cheng Hu Chengxiang Liu Yang Sun Science and Technology on Complex Electronic System Simulation Laboratory Space Engineering University Beijing China School of Information and Electronics Beijing Institute of Technology Beijing China

ISBN: (数字)9780996007894

ISBN: (纸本)9781728146331

GEO SAR has great potential in marine surveillance. But the extremely low SNR of echo, resulting in the traditional signal integration method become invalid. This paper proposes an improved GRFT-based approach to realize the moving ship targets' radial accelerated velocity estimation. Firstly, the accurate slant range is constructed which has considered the curved synthetic aperture trajectory. Then, the GRFT-based estimation method is redefined to realize radial accelerated velocity estimation and imaging. Finally, the simulation results are given to verify the proposed methods.

关键词： Acceleration Marine vehicles Synthetic aperture radar Estimation Imaging systems simulation Aerospace electronics

来源：评论

学校读者我要写书评

暂无评论

Climatic and Biotic Controls of Evapotranspiration Across Grassland Ecosystems on Tibetan Plateau

SSRN

引用

SSRN 2024年

作者： Peng, Siyuan Yang, Yue Luo, Dengnan Zeng, Xiang Liang, Minqi Tao, Long Zhang, Guangru Li, Pan Liao, Weijie Guo, Qun Cao, Ruochen Li, Yuzhe Zhang, Weirong Hu, Zhongmin School of Geography South China Normal University Shipai Campus Guangzhou510631 China Hainan Baoting Tropical Rainforest Ecosystem Observation and Research Station Key Laboratory of Agro-Forestry Environmental Processes and Ecological Regulation School of Ecology and Environment Hainan University Haikou570228 China Center for Eco-Environment Restoration Engineering of Hainan Province Hainan University Haikou570228 China Facility of Geographical Science Beijing Normal University Beijing100875 China Zhuhai Branch of State Key Laboratory of Earth Surface Processes and Resource Ecology Beijing Normal University Zhuhai519087 China School of Atmospheric Sciences Guangdong Province Data Center of Terrestrial and Marine Ecosystems Carbon Cycle Sun Yat-sen University Guangdong Zhuhai510245 China Key Lab of Ecosystem Network Observation and Modeling Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing100101 China College of Resources and Environment University of Chinese Academy of Sciences Beijing101408 China International Institute for Earth System Sciences Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application Nanjing University Jiangsu210023 China Jiangsu Provincial Key Laboratory of Geographic Information Science and Technology Key Laboratory for Land Satellite Remote Sensing Applications of Ministry of Natural Resources School of Geography and Ocean Science Nanjing University Jiangsu210023 China Key Laboratory of Land Surface Pattern and Simulation Institute of Geographical Sciences and Natural Resources Research Chinese Academy of Sciences Beijing China

Understanding the spatial variations of evapotranspiration (ET) and its components on Tibetan Plateau (TP) is pivotal for grasping the regional water cycle and energy balance dynamics. Yet it is unclear how the changes of the intricate synergy among diverse environment factors significantly impacts the patterns of ET and its transformation state. Addressing this gap, this study employed observational data from 14 sites, utilizing the Shuttleworth-Wallace-Hu (SWH) model to investigate the spatial relationships between ET, its components, and influencing factors. Model parameters of SWH were optimized by Monte Carlo method, achieving a commendable simulation performance with a mean R2 value of 0.75. Our analysis reveals that in alpine meadow, the ratio of transpiration (T) to ET (T/ET) is generally higher (0.55) compared to alpine steppe (0.39). The T/ET values for hover around or below 0.5, indicating a balanced contribution of various ET components. Spatially, both PPT and LAI have an impact on ET and T/ET. PPT emerges as the primary driver of interannual spatial variations in ET, while LAI plays a crucial role in regulating T/ET. Our results further demonstrate that a transition from water-dominated to energy-dominated systems in TP grassland ecosystem at an approximately aridity index of 0.73. This is noteworthy considering the general application of an aridity index of 0.65 to delineate arid from humid regions. It implies that TP grasslands, within the 0.65-0.73 range, remain primarily water-driven. This insight holds substantial implications for comprehending water-energy dynamics in similar ecosystems, challenging the conventional binary categorization of arid and humid areas. Such findings are of immense significance in enhancing understanding of the intricate interactions of the water cycle between land and the atmosphere. © 2024, The Authors. All rights reserved.

关键词： Water supply

来源：评论

学校读者我要写书评

暂无评论

Application of the view factor model on the particle-in-cell and Monte Carlo collision code

引用

Physical Review E 2020年第3期102卷 033311-033311页

作者： Ruojian Pan Junxue Ren Haibin Tang Shuai Cao Juan Li Zhe Zhang Jun Zhou Jinbin Cao School of Space and Environment Beihang University Beijing 100083 China School of Astronautics Beihang University Beijing 100083 China Key Laboratory of Spacecraft Design Optimization and Dynamic Simulation Technologies Ministry of Education Beijing 100083 China Laboratory of Space Environment monitoring and Information Processing Ministry of Industry and Information Technology Beijing 100083 China National Key Laboratory of Science and Technology on Vacuum Technology & Physics Lanzhou Institute of Physics Lanzhou 730000 China School of Instrumentation and Optoelectronic Engineering Beihang University Beijing 100083 China

Particle-in-cell and Monte Carlo collision (PIC-MCC) has been widely adopted as a simulation method for electric propulsion. However, neutral atoms move much more slowly than other species, which can cause a serious reduction in simulation speed. In this work, we investigate the view factor model in combination with the PIC-MCC method and propose a method for simulating three-dimensional neutral atoms. The accuracy of the PIC-MCC method can be significantly improved by updating the neutral distribution periodically. We compare the computational results with the fixed-neutral PIC-MCC model of the miniature ring-cusp discharge experiment at the University of California, Los Angeles (UCLA). The plasma distribution and potential distribution of the simulation match well with the UCLA experimental data. Compared with the fixed-neutral model, the view factor model increases the simulation time by only 33% while it improves the distribution accuracy of neutrals, plasma density, and electric potential, and reduces the simulation errors of discharge current and discharge power from 19.8% to 9.8%. The accuracy of PIC-MCC simulation has been improved at the expense of slightly increasing the computational time.

关键词： Particle-in-cell methods

来源：评论

学校读者我要写书评

暂无评论

Range migration-based Doppler ambiguous integer estimation for moving targets with azimuth spectrum aliasing

Range migration-based Doppler ambiguous integer estimation f...

引用

Asian and Pacific Conference on Synthetic Aperture Radar (APSAR)

ISBN: (数字)9781728129129

ISBN: (纸本)9781728129136

In some case, the azimuth spectrum bandwidth is larger than the pulse repetition frequency (PRF), leading to a whole azimuth spectrum has been folded into multiple subsegments and aliased. Therefore, the traditional Doppler ambiguous integer estimation method cannot be used directly. In this paper, the influence of Doppler ambiguous integer on residual range migrations' slope is analyzed. Based on the slope, the Doppler ambiguous integer estimation method for moving targets with azimuth spectrum aliasing is given. From the simulation results, the Doppler ambiguous integer can be estimated accurately by proposed method.

关键词：

来源：评论

学校读者我要写书评

暂无评论

A Novel Geosynchronous spaceborne-Airborne Bistatic Multichannel Sar For Ground Moving Targets Indication

A Novel Geosynchronous Spaceborne-Airborne Bistatic Multicha...

引用

IEEE International Symposium on Geoscience and Remote Sensing (IGARSS)

作者： Xichao Dong Wei Xiong Ying Zhang Cheng Hu Feifeng Liu School of Information and Electronics Beijing Institute of Technology Beijing China Science and Technology on Complex Electronic System Simulation Laboratory Space Engineering University Beijing China

Geosynchronous synthetic aperture radar (GEO SAR) has great potentials in synthetic aperture radar ground moving target indication (SAR-GMTI) due to its high time resolution and wide swath coverage. But the signal-to-noise ratio (SNR) of echo is too low and multichannel configuration cannot be realize in GEO monostatic SAR. Therefore, geosynchronous spaceborne-airborne bistatic multichannel synthetic aperture radar (GEO-SABM SAR) can realize enhanced SNR and multichannel configuration. In this paper, we establish the slant range model for GEO-SABM SAR and give the VSAR processing flowchart. Finally, the numerical experiments is given to verify the effectiveness of proposed method.

关键词： Synthetic aperture radar Clutter Doppler effect Imaging Flowcharts Orbits Remote sensing

来源：评论

学校读者我要写书评

暂无评论

The impact of rain to observed signal from Chinese Gaofen-3 synthetic aperture radar in typhoons

引用

Acta Oceanologica Sinica 2019年第11期38卷 121-133页

作者： Jian Shi Jiachen Hu Weizeng Shao Xiaoqing Wang Xinzhe Yuan Liangbo Zhao Xiaofeng Li College of Meteorology and Oceanography National University of Defense TechnologyNanjing 211101China Marine Science and Technology College Zhejiang Ocean UniversityZhoushan 316022China School of Electronics and Communication Engineering Sun Yat-sen UniversityGuangzhou 510275China Key Laboratory of Space Ocean Remote Sensing and Application National Satellite Ocean Application ServiceBeijing 100081China Institute of Spacecraft System Engineering China Academy of Space TechnologyBeijing 100094China

Gaofen-3(GF-3),a Chinese civil synthetic aperture radar(SAR)at C-band,has operated since August ***,several typhoons have been captured by GF-3 around the China Seas over its last two-year *** this study,six images acquired in Global Observation(GLO)and Wide ScanSAR(WSC)modes at verticalvertical(VV)polarization channel are *** work focuses on investigating the observation of rainfall using GF-3 *** images were collocated with winds from the European Centre for Medium-Range Weather Forecasts(ECMWF),significant wave height simulated from the WAVEWATCH-III(WW3)model,sea surface currents from climate forecast system version 2(CFSv2)of the National Centers for Environmental Prediction(NCEP)and rain rate data from the Tropical Rainfall Measuring Mission(TRMM)*** surface roughness,was compared with the normalized radar cross section(NRCS)from SAR observations,and indicated a 0.8 correlation(COR).We analyzed the dependences of the difference between model-simulated NRCS and SARmeasured NRCS on the TRMM rain rate and WW3-simulated significant wave *** was found that the effects of rain on SAR damps the radar signal at incidence angles ranging from 15°to 30°,while it enhances the radar signal at incidence angles ranging from 30°to 45°and incidence angles smaller than 10°.This behavior is consistent with previous studies and an algorithm for rain rate retrieval is anticipated for GF-3 SAR.

关键词： Gaofen-3 synthetic aperture radar typhoon

来源：评论

学校读者我要写书评

暂无评论

Flexible data handling in the flight control decision software for space science satellites 15th

Flexible data handling in the flight control decision softwa...

引用

15th International Conference on space Operations, spaceOps 2018

作者： Zhang, Y.Z. Peng, X.D. Gao, C. Laboratory of System Simulation and Concurrent Design Technology National Space Science Center Chinese Academy of Sciences Beijing100190 China Laboratory of System Simulation and Concurrent Design Technology University of Chinese Academy of Sciences Beijing100049 China

ISBN: (纸本)9781624105623

In order to support the in-orbit operation of the satellites in the Strategic Priority Program on space science, the Flight Control Decision Support Software (FCDSS) is developed. It belongs to the mission operation subsystem of the ground support system of the Strategic Priority Program on space science. The FCDSS is responsible for the comprehensive analysis of the operating status of the onboard equipment, the use of the satellite resources, the scientific detection results, and full life cycle visualization of the scientific mission in real time and afterwards, and mission situation analysis. The software contains two parts--"Flight Control Decision Analysis and Comprehensive Situation Visualization Unit" and "Full-lifecycle Data Processing Unit". The latter is the main focus in this paper. It is responsible for acquiring required data (such as telemetry data) from the database and do calculations for coverage analysis, observation plan analysis and etc. Due to the various types and massive amount of data need to be processed, it posed high requirements to data processing. In brief, in this paper, we will first describe the software architecture in detail. Then, give detailed information on the design and implementation of the data processing layer. At last, mission applications of the software will be shown with conclusions on the performance and lessons we have learned as the four mission carries on. © 2018, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

关键词： Visualization

来源：评论

学校读者我要写书评

暂无评论

One-proton emission from 148−151Lu in the DRHBc+WKB approach

arXiv

引用

arXiv 2023年

作者： Xiao, Yang Xu, Si-Zhe Zheng, Ru-You Sun, Xiang-Xiang Geng, Li-Sheng Zhang, Shi-Sheng School of Space and Environment Beihang University Beijing102206 China School of Physics Beihang University Beijing102206 China Institut für Kernphysik Institute for Advanced Simulation Jülich Center for Hadron Physics Forschungszentrum Jülich JülichD-52425 Germany School of Nuclear Science and Technology University of Chinese Academy of Sciences Beijing100049 China Peng Huanwu Collaborative Center for Research and Education Beihang University Beijing100191 China Beijing Key Laboratory of Advanced Nuclear Materials and Physics Beihang University Beijing102206 China Institute of Modern Physics Chinese Academy of Sciences Guangdong Province Huizhou516000 China

One-proton radioactivity in 149Lu, the latest identified proton emitter, is studied in the Wentzel-Kramers-Brillouin (WKB) approach with the proton-nucleus potential extracted from the deformed relativistic Hartree-Bogoliubov theory in continuum (DRHBc) for the first time. The predicted half-life turns out to be consistent with the experimental measurement within uncertainties and (almost) independent of the density functionals in the DRHBc theory. Such a microscopic self-consistent calculation reveals that 149Lu is oblately deformed with a quadrupole deformation β2 ≈ −0.18, and rules out the possibility of a prolate quadrupole deformation suggested in the nonadiabatic quasiparticle model. We also check the validity of this approach in the description of 150,151Lu and their isomeric states. The deviations of the predicted half-lives from their experimental counterparts are mostly smaller than those of the theoretical studies without considering deformation effects. Furthermore, we predict 148Lu to be a more oblately deformed proton-emitter with a longer half-life than that of 149Lu, which can be checked in the future. Our studies show that the DRHBc + WKB approach provides a new alternative method to evaluate the half-lives of well-deformed proton emitters. © 2023, CC BY.

关键词： Uncertainty analysis

来源：评论

学校读者我要写书评

暂无评论

Compound extreme events and health risks in China: A review

引用

Atmospheric and Oceanic science Letters 2025年

作者： Haosu Tang Gang Huang Kaiming Hu Jun Wang Cunrui Huang Xianke Yang School of Geography and Planning University of Sheffield Sheffield UK 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. 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.加强上述方

关键词： Global warming Extreme weather Compound extreme event Air pollution Population health Carbon neutrality 全球变暖极端天气复合型极端事件大气污染人群健康碳中和

来源：评论

学校读者我要写书评

暂无评论

Better Modeling the Hierarchical Structure of Language for Sentence Semantic Matching

引用

Journal of Physics: Conference Series 2020年第1期1651卷

作者： Zhongmin Pei Changqun Li Wei Xiong Zhangkai Luo Science and Technology on Complex Electronic System Simulation Laboratory Space Engineering University Beijing 100014 China

Sentence semantic matching requires understanding the semantic relationship between two sentences, which is widely used in various natural language tasks such as paraphrase identification, natural language inference and question answering. Usually, the underlying structure of sentence is not strictly sequential, this structure is hierarchical. This paper studies how to better model the hierarchical structure of sentence for semantic matching. Recent research suggests that BERT implicitly captures classical, tree-like structures. Based on this, this paper proposes to further enhance the strength of modeling hierarchical structure of language with an advanced variant of LSTM – Ordered Neurons LSTM(ON-LSTM), which introduces a syntax-oriented inductive bias to perform the composition of classical tree structure. Experimental results demonstrate that the proposed approach, which enhances hierarchical structure of language, significantly improves the performance of sentence semantic matching.

关键词：

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：