检索结果-内蒙古大学图书馆

The Role of Regional Ocean–Atmosphere Coupling in Simulating the2020 Extreme Mei-yu Event

Advances in Atmospheric sciences 2025年第05期 904-920页

作者： Kai LI Liwei ZOU Li DAN Hui ZHENG Zhongfeng XU Jianping TANG Fuqiang YANG Wenli FEI Taotao ZHANG Chunxiang SHI Zong-Liang YANG Key Laboratory of Regional Climate and Environment for Temperate East Asia Institute of Atmospheric PhysicsChinese Academy of Sciences Key Laboratory of Meteorological Disaster (KLME) Ministry of Education & Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters (CIC-FEMD) Nanjing University of Information Science & Technology State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics (LASG) Institute of Atmospheric Physics Chinese Academy of Sciences School of Atmospheric Sciences Nanjing University Institute of Applied Ecology Chinese Academy of Sciences National Meteorological Information Center China Meteorological Administration Department of Earth and Planetary Sciences Jackson School of GeosciencesThe University of Texas at Austin

The Yangtze–Huaihe River Valley(YHRV) experienced a record-breaking mei-yu season during the summer of 2020,prompting investigation into the role of regional ocean–atmosphere coupling in simulating this extreme event. Through comparative analysis of regional ocean–atmosphere coupled(CP) and atmosphere-only(WRF) simulations, the aim of this study was to elucidate the mechanisms underlying this phenomenon. Results indicate that CP effectively reproduced the observed sea surface temperature spatial distribution and its daily variation during the period from 25 June to 25 July 2020,and notably reduced the wet biases over the YHRV when compared to WRF simulations. This improvement in representation was manifested in the observed rainfall spatial distribution and daily variability. The wet biases simulated by WRF were associated with a stronger 200-h Pa westerly jet and a more westward-positioned western North Pacific subtropical high(WNPSH) with more intense 500-h Pa winds and a stronger 850-h Pa circulation. However, these biases were significantly reduced in CP simulations. Mechanism analysis revealed that regional ocean–atmosphere coupling over the western Northwest Pacific influenced surface turbulent heat fluxes and atmospheric instability, thereby modulating the intensity and position of the WNPSH and associated circulation subsystems at different levels. Moreover, adjustments in land–sea thermal contrast induced by ocean–atmosphere coupling impacted YHRV precipitation by altering East Asian circulation systems. These findings highlight the significant role of regional ocean–atmosphere coupling in enhancing the simulation and understanding of extreme mei-yu events over East Asia.

关键词：

来源：评论

学校读者我要写书评

暂无评论

Design of W-band Sheet Beam EIK

Design of W-band Sheet Beam EIK

引用

Asia-Pacific Conference on Microwave

作者： Shuyuan Chen Jinliang Bai Ran Zhang Pei Zheng Jiaqi Liu Xin Liu Hongyan Liu Lu Gao National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing China

ISBN: (数字)9781728135175

ISBN: (纸本)9781728135182

Microwave tube is a vacuum electron device which can be used for amplification in the microwave frequency range. Sheet beam Extended Interaction Klystron (EIK) is an attractive Millimeter Waves amplifier because of its compact configuration, small voltage and high gain per unit length. In this paper, RF structure and the whole tube for W-band sheet beam EIK has been designed. A new and effective method of designing and studying W-band sheet beam EIK is presented in this paper. In order to get the same output power, several kinds of W-band sheet beam EIK are designed and compared. By optimizing the position of cavities, the output power can achieve 30 kW, which is calculated by threedimensional particle in cell (3D-PIC) software. It is a powerful basis for the subsequent study of sheet beam EIK.

关键词： Power generation Klystrons Power amplifiers physics mathematics Urban areas

来源：评论

学校读者我要写书评

暂无评论

Near-field Measurement Method for Electromagnetic Scattering of Electrically Large-scale Plasma

Near-field Measurement Method for Electromagnetic Scattering...

引用

International Applied Computational Electromagnetics Society Symposium (ACES)

作者： Jiaqi Liu Lu Gao Runhui Wu Xia Ai Song Chai Xin Liu Shengjun Zhang Yichun Cui National Key Laboratory of Science and Technology on Test Physics & Numerical Mathematics Beijing China

In the near-field test environment of 01500×3300mm vacuum vessel with low electromagnetic scattering, the relative measurement method is used, that is, the results of electrically large-scale plasma radar cross s... 详细信息

关键词： Radar cross-sections Volume measurement Standards organizations Electromagnetic scattering Elementary particle vacuum Energy measurement Plasma measurements

来源：评论

学校读者我要写书评

暂无评论

A New Criterion For Optimization Of Total Variation Denoising

A New Criterion For Optimization Of Total Variation Denoisin...

引用

International Applied Computational Electromagnetics Society Symposium (ACES)

作者： Feng Xue Xia Ai Lu Gao Jiaqi Liu National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing China

Based on Chambolle’s algorithm, we develop a data-driven optimization scheme based on minimization of Stein’s unbiased risk estimate (SURE)—statistically equivalent to mean squared error (MSE). We propose a recursive evaluation of SURE to monitor the estimation error during Chambolle’s iteration; the optimal value is then identified by the minimum SURE. We exemplify the proposed methods with 1-D signal denoising.

关键词： Estimation error Deconvolution Noise reduction Minimization Computational electromagnetics Signal denoising Optimization

来源：评论

学校读者我要写书评

暂无评论

An Updated Estimation of Radiative Forcing due to CO_2 and Its Effect on Global Surface Temperature Change

引用

Advances in Atmospheric sciences 2013年第4期30卷 1017-1024页

作者：张华张若玉石广玉 Laboratory for Climate Studies China Meteorological Administration National Climate Center Atmosphere Science Academy Nanjing University of Information Science and Technology State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric Physics

New estimations of radiative forcing due to CO2 were calculated using updated concentration data of CO2 and a high-resolution radiative transfer model. The stratospheric adjusted radiative forcing （ARF） due to CO2 from the year 1750 to the updated year of 2010 was found to have increased to 1.95 W m-2, which was 17% larger than that of the IPCC＇s 4th Assessment Report because of the rapid increase in CO2 concentrations since 2005. A new formula is proposed to accurately describe the relationship between the ARF of CO2 and its concentration. Furthermore, according to the relationship between the ARF and surface temperature change, possible changes in equilibrium surface temperature were estimated under the scenarios that the concentration of CO2 increases to 1.5, 2, 2.5, 3, 3.5 and 4 times that of the concentration in the year 2008. The result was values of ＋2.2℃, ＋3.8℃, ＋5.1℃, ＋6.2℃, ＋7.1℃ and ＋8.0℃ respectively, based on a middle-level climate sensitivity parameter of 0.8 K （W m 3）-1. Non-equilibrium surface temperature changes over the next 500 years were also calculated under two kinds of emission scenarios （pulsed and sustained emissions） as a comparison, according to the Absolute Global Temperature change Potential （AGTP） of CO2. Results showed that CO2 will likely continue to contribute to global warming if no emission controls are imposed, and the effect on the Earth-atmosphere system will be difficult to restore to its original level.

关键词： CO2 radiative forcing surface temperature change Global Temperature change Potential

来源：评论

学校读者我要写书评

暂无评论

UAV Track Planning Algorithm Based on Graph Attention Network and Deep Q Network 11th

UAV Track Planning Algorithm Based on Graph Attention Networ...

引用

11th International Conference on Image and Graphics, ICIG 2021

作者： Hu, Xinyu Gao, Jingpeng Jiang, Zhiye College of Information and Communication Engineering Harbin Engineering University Harbin China National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing Institute of Space Long March Vehicle Beijing China

ISBN: (纸本)9783030873578

To solve the problem that the deviation of the Unmanned Aerial Vehicle (UAV) flight status data collected by the equipment during flight leads to the failure of the mission, this paper proposes a UAV track planning algorithm based on Graph Attention Network and Deep Q Network (DQN). Firstly, we use the camera to collect images and apply pre-trained ResNet to extract image features. Secondly, we adopt the Graph Attention Network to establish the connection between the sensor-measured flight state information and the actual flight state information. Thirdly, we build the optimization model of flight state. Moreover, based on the Deep Reinforcement Learning (DRL) theory, the DQN-based UAV track planning system is trained. Finally, the system combined the optimized flight state to complete the optimal flight action output to realize the track planning. Simulation results show that, compared with the original algorithm which is under the same flight conditions as the proposed algorithm, the velocity deviation rate of the proposed algorithm is improved by 46.79%, which can plan a high-quality track and has good engineering application value. © 2021, Springer Nature Switzerland AG.

关键词： Image processing

来源：评论

学校读者我要写书评

暂无评论

Attitude maneuver path optimization for small scale spacescraft

Attitude maneuver path optimization for small scale spacescr...

引用

International Symposium on Applied Machine Intelligence and Informatics (SAMI)

作者： Runle Du Jiaqi Liu Yonghai Wang Test Physics and Numerical Mathematics National Key Laboratory of Science and Technology Beijing China

During its flight, Spacecrafts need to maneuver its attitude across a number of predefined positions. The order to traverse these attitudes is a combinational optimization problem. In this article, fuel cost is estimated by analyzing the angular momentum change during attitude transitions. Based on this estimation, an optimization algorithm for both fuel-cost and maneuver-time oriented path planner is introduced. Simulation result demonstrated the effectiveness of proposed approach.

关键词： Attitude control Fuels Space vehicles Path planning Switches Optimization Heuristic algorithms

来源：评论

学校读者我要写书评

暂无评论

SPECTRAL-SPATIAL ATTENTION FUSION TRANSFORMER FOR HYPERSPECTRAL IMAGE CLASSIFICATION

SPECTRAL-SPATIAL ATTENTION FUSION TRANSFORMER FOR HYPERSPECT...

引用

IET International Radar Conference 2023, IRC 2023

作者： Ji, Xiangyu Gao, Jingpeng Chen, Geng Gao, Lu College of Information and Communication Engineering Harbin Engineering University Harbin China National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing Institute of Space Long March Vehicle Beijing China

ISBN: (纸本)9781839539954

In view of the limited generalization and poor local feature information modeling ability of vision transformer model(ViT) in hyperspectral image classification, a Spectral-Spatial Attention Fusion Transformer (SAFT) method for hyperspectral image classification is proposed in this paper. The proposed method includes two key modules: Spectral-Spatial Feature Extraction Module (SSFE) and Multi-Head Attention Fusion Transformer Module (MAFT). The SSFE module is a lightweight network. It contains a 3D convolution block and a 2D convolution block, which can efficiently obtain local feature information. Based on the proposed attention fusion structure, the MAFT module designs an improved transformer encoder. It improves the generalization ability of the model on the premise of obtaining global information. In this paper, two datasets of HyRANK are used for experiments. The experimental results show that this method is superior to other HSI classification methods. © The Institution of Engineering & technology 2023.

关键词： Convolutional neural networks

来源：评论

学校读者我要写书评

暂无评论

Guidance law recognition of target pursuing vehicle

Guidance law recognition of target pursuing vehicle

引用

IEEE Metrology for Aerospace

作者： Runle Du Jiaqi Liu Zhifeng Li Zhenhong Niu National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing China

Research on guidance law has begun to incorporate behavior information from non-cooperative target, and thus emphasized the importance and necessity of guidance law recognition. Recognition of guidance law on non-cooperative vehicle is highly supportive for pursued vehicle to conduct guidance law optimization, guidance law evaluation, and trajectory prediction. Huge variety of design and implementation of guidance law made recognition a hard problem. In this paper, a generic implicit guidance function is proposed to establish unified description of all known guidance laws. A practical model with time-varying guidance parameter is formulated to approximate generic implicit guidance function, and a Kalman Filter based observation data processing algorithm is proposed to build real-time guidance recognition. Simulation results show that, whether the vehicle under pursuit maneuvers or not, the guidance parameters of pursuing vehicle change or not, recognition algorithm can provide reasonable results.

关键词： Vehicles Kalman filters Trajectory Target recognition Target tracking Optimization Chapters

来源：评论

学校读者我要写书评

暂无评论

Effective Observing Area based evaluating method for formation design

Effective Observing Area based evaluating method for formati...

引用

IEEE AESS European Conference on Satellite Telecommunications (ESTEL)

作者： Runle Du Jiaqi Liu Yonghai Wang Yizhong Fang Gang Meng National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing China

When multiple flying vehicles collaborate in locating a target, their formation design is an important factor to the error of location. Based on the analyses of contribution that formation design made to the location error, Effective Observing Area is defined as a criterion to assess formation design. An evaluation method for formation design is then proposed in this paper, which can serve as a guide in further formation design. Digital simulation results have proved the effectiveness and correct of this concept.

关键词： Vectors Target tracking Algorithm design and analysis Space vehicles Extraterrestrial measurements

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：