检索结果-南通市图书馆

Influences of Earth Incidence Angle on FY-3/MWRI SST Retrieval and Evaluation of Reprocessed SST

Journal of Tropical Meteorology 2024年第3期30卷 230-240页

作者： ZHANG Miao CHEN Lin XU Na CAO Guang-zhen Key laboratory of Radiometric Calibration and Validation for Environmental satellites National Satellite Meteorological CenterChina Meteorological AdministrationBeijing 100081 China Innovation Center for FengYun Meteorological satellite(FYSIC) Beijing 100081 China

Sea surface temperature(SST)is a crucial physical parameter in meteorology and *** study demonstrates that the influence of earth incidence angle(EIA)on the SST retrieved from the microwave radiation imager(MWRI)onboard FengYun-3(FY-3)meteorological satellites should not be *** with algorithms that do not consider the influence of EIA in the regression,those that integrate the EIA into the regression can enhance the accuracy of SST ***,based on the recalibrated Level 1B data from the FY-3/MWRI,a long-term SST dataset was reprocessed by employing the algorithm that integrates the EIA into the *** reprocessed SST data,including FY-3B/MWRI SST during 2010-2019,FY-3C/MWRI SST during 2013-2019,and FY-3D/MWRI SST during 2018-2020,were compared with the in-situ SST and the SST dataset from the Operational Sea Surface Temperature and Ice Analysis(OSTIA).The results show that the FY-3/MWRI SST data were consistent with both the in-situ SST and the OSTIA SST *** with the Copernicus Climate Change Service V2.0 SST,the absolute deviation of the reprocessed SST,with a quality flag of 50,was less than 1.5℃.The root mean square errors of the FY-3/MWRI orbital,daily,and monthly SSTs,with a quality flag of 50,were approximately 0.82℃,0.69℃,and 0.37℃,*** primary discrepancies between the FY-3/MWRI SST and the OSTIA SST were found mainly in the regions of the western boundary current and the Antarctic Circumpolar ***,this reprocessed SST product is recommended for El Niño and La Niña events monitoring.

关键词： FengYun-3 satellites sea surface temperature microwave radiation imager earth incidence angle reprocessing

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Progress and Achievements of Fengyun Meteorological satellite Program since 2022

引用

空间科学学报 2024年第4期44卷 712-721页

作者： GUAN Min WANG Jingsong ZHAO Xiangang QIN Danyu FAN Cunqun XIAN Di LIU Chang National satellite Meteorological Center(National Centre for Space Weather) Beijing 100081 Innovation Center for Fengyun Meteorological satellite(FYSIC) Beijing 100081 Key laboratory of Radiometric Calibration and Validation for Environmental satellites/Key laboratory of Space Weather China Meteorological AdministrationBeijing 100081

Fengyun meteorological satellites have undergone a series of significant developments over the past 50 *** generations,four types,and 21 Fengyun satellites have been developed and launched,with 9 currently operational in *** data obtained from Fengyun satellites is employed in a multitude of applications,including weather forecasting,meteorological disaster prevention and reduction,climate change,global environmental monitoring,and space *** data products and services are made available to the global community,resulting in tangible social and economic *** 2023,two Fengyun meteorological satellites were successfully *** report presents an overview of the two recently launched Fengyun satellites and currently in orbit Fengyun satellites,including an evaluation of their remote sensing instruments since ***,it addresses the subject of Fengyun satellite data archiving,data services,application services,international cooperation,and supporting ***,the development prospects have been outlined.

关键词： Fengyun meteorological satellites Data services and application International cooperation and support

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Perturbed low-thrust geostationary orbit transfer guidance via polynomial costate estimation

引用

Chinese Journal of Aeronautics 2024年第3期37卷 181-193页

作者： Zhao LI Hengnian LI Fanghua JIANG Junfeng LI State Key laboratory of Astronautic Dynamics Xi’an Satellite Control CenterXi’an 710043China School of Aerospace Engineering Tsinghua UniversityBeijing 100084China

This paper proposes an optimal,robust,and efficient guidance scheme for the perturbed minimum-time low-thrust transfer toward the geostationary *** Earth’s oblateness perturbation and shadow are taken into *** is difficult for a Lyapunov-based or trajectory-tracking guidance method to possess multiple characteristics at the same time,including high guidance optimality,robustness,and onboard computational *** this work,a concise relationship between the minimum-time transfer problem with orbital averaging and its optimal solution is identified,which reveals that the five averaged initial costates that dominate the optimal thrust direction can be approximately determined by only four initial modified equinoctial orbit elements after a coordinate *** on this relationship,the optimal averaged trajectories constituting the training dataset are randomly generated around a nominal averaged *** polynomial regression models are trained on the training dataset and are regarded as the costate *** the transfer,the spacecraft can obtain the real-time approximate optimal thrust direction by combining the costate estimations provided by the estimators with the current state at any ***,all these computations onboard are *** simulation results show that the proposed guidance scheme possesses extremely high guidance optimality,robustness,and onboard computational efficiency.

关键词： Low thrust Orbital transfer Trajectory optimization Guidance Indirect method Orbital averaging Machine learning Geostationary satellites

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

A Recursive DRL-Based Resource Allocation Method for Multibeam satellite Communication Systems

引用

Chinese Journal of Electronics 2024年第5期33卷 1286-1295页

作者： Haowei MENG Ning XIN Hao QIN Di ZHAO State Key laboratory of Integrated Services Networks Xidian University China Academy of Space Technology Institute of Telecommunication Satellite

Optimization-based radio resource management(RRM) has shown significant performance gains on high-throughput satellites(HTSs). However, as the number of allocable on-board resources increases, traditional RRM is difficult to apply in real satellite systems due to its intense computational complexity. Deep reinforcement learning(DRL) is a promising solution for the resource allocation problem due to its model-free advantages. Nevertheless, the action space faced by DRL increases exponentially with the increase of communication scale, which leads to an excessive exploration cost of the algorithm. In this paper, we propose a recursive frequency resource allocation algorithm based on long-short term memory(LSTM) and proximal policy optimization(PPO), called PPO-RA-LOOP,where RA means resource allocation and LOOP means the algorithm outputs actions in a recursive manner. Specifically, the PPO algorithm uses LSTM network to recursively generate sub-actions about frequency resource allocation for each beam, which significantly cuts down the action space. In addition, the LSTM-based recursive architecture allows PPO to better allocate the next frequency resource by using the generated sub-actions information as a prior knowledge, which reduces the complexity of the neural network. The simulation results show that PPO-RA-LOOP achieved higher spectral efficiency and system satisfaction compared with other frequency allocation algorithms.

关键词： High-throughput satellites Proximal policy optimization Deep reinforcement learning Long-short term memory High-throughput satellites Proximal policy optimization Deep reinforcement learning Long-short term memory OPTIMIZATION POWER

来源：

同方期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

A self-centering and stiffness-controlled MEMS accelerometer

引用

Microsystems & Nanoengineering 2024年第1期10卷 27-40页

作者： Yiming Jin Zhipeng Ma Ziyi Ye Mingkang Li Xudong Zheng Zhonghe Jin School of Aeronautics and Astronautics Zhejiang UniversityHangzhou 310013China Key laboratory of Micro/Nano-satellite Research of Zhejiang Province Hangzhou 310007PR China

This paper presents a high-performance MEMS accelerometer with a DC/AC electrostatic stiffness tuning capability based on double-sided parallel plates(DSPPs).DC and AC electrostatic tuning enable the adjustment of the effective stiffness and the calibration of the geometric offset of the proof mass,respectively.A dynamical model of the proposed accelerometer was developed considering both DC/AC electrostatic tuning and the temperature *** on the dynamical model,a self-centering closed loop is proposed for pulling the reference position of the forceto-rebalance(FTR)to the geometric center of *** self-centering accelerometer operates at the optimal reference position by eliminating the temperature drift of the readout circuit and nulling the net electrostatic tuning *** stiffness closed-loop is also incorporated to prevent the pull-in instability of the tuned low-stiffness accelerometer under a dramatic temperature ***-time adjustments of the reference position and the DC tuning voltage are utilized to compensate for the residue temperature drift of the proposed *** a result,a novel controlling approach composed of a self-centering closed loop,stiffness-closed loop,and temperature drift compensation is achieved for the accelerometer,realizing a temperature drift coefficient(TDC)of approximately 7μg/℃ and an Allan bias instability of less than 1μg.

关键词： stiffness electrostatic centering

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Staring-imaging satellite pointing estimation based on sequential ISAR images

引用

Chinese Journal of Aeronautics 2024年第8期37卷 261-276页

作者： Canyu WANG Libing JIANG Weijun ZHONG Xiaoyuan REN Zhuang WANG National Key laboratory of Automatic Target Recognition National University of Defense TechnologyChangsha 410073China Xi’an satellite Control Center Xi’an 710600China

Pointing estimation for spacecraft using Inverse Synthetic Aperture Radar(ISAR)images plays a significant role in space situational awareness and ***,feature extraction and cross-range scaling of ISAR images create bottlenecks that limit performances of current estimation ***,the emergence of staring imaging satellites,characterized by complex kinematic behaviors,presents a novel challenge to this *** address these issues,this article proposes a pointing estimation method based on Convolutional Neural Networks(CNNs)and a numerical optimization algorithm.A satellite’s main axis,which is extracted from ISAR images by a proposed Semantic Axis Region Regression Net(SARRN),is chosen for investigation in this article due to its unique ***,considering the kinematic characteristic of the staring satellite,an ISAR imaging model is established to bridge the target pointing and the extracted *** on the imaging model,pointing estimation and cross-range scaling can be described as a maximum likelihood estimation problem,and an iterative optimization algorithm modified by using the strategy of random sampling-consistency check and weighted least squares is proposed to solve this ***,the pointing of targets and the cross-range scaling factors of ISAR images are *** experiments based on actual satellite orbital parameters verify the effectiveness of the proposed *** work can improve the performance of satellite reconnaissance warning,while accurate cross-range scaling can provide a basis for subsequent data processes such as 3D reconstruction and attitude estimation.

关键词： Staring-imaging Agile satellite Inverse Synthetic Aperture Radar(ISAR) Pointing estimation Cross-range scaling

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Global intensification of weak tropical cyclones in the past 30 years

引用

Science China Earth Sciences 2024年第2期67卷 639-640页

作者： Dake CHEN State Key laboratory of satellite Ocean Environment Dynamics Second Institute of OceanographyMinistry of Natural ResourcesHangzhou 310012China Southern Marine Science and Engineering Guangdong laboratory(Zhuhai) Zhuhai 519000Chin

The response of tropical cyclones(TCs)to climate change is a hot topic in ocean and atmosphere *** theoretical analysis and numerical experiments indicated that the intensity of TCs may increase with global warming(Emanuel,1987;Knutson and Tuleya,2004),which however has not been convincingly validated by presently available observations(Landsea,2005;Pielke,2005).Using a huge amount of global ocean surface drifter data,Wang et al.

关键词： tropical ocean cyclones

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Service Function Chain Migration in LEO satellite Networks

引用

China Communications 2024年第3期21卷 247-259页

作者： Geng Yuhui Wang Niwei Chen Xi Xu Xiaofan Zhou Changsheng Yang Junyi Xiao Zhenyu Cao Xianbin School of Electronic and Information Engineering Beihang UniversityBeijing 100191China Key laboratory of Advanced Technology of Near Space Information System Ministry of Industry and Information Technology of ChinaBeijing 100191China Shanghai Key laboratory of satellite Network Shanghai 201204China Shanghai satellite Network Research Institute Co. Ltd.Shanghai 201204China

With the advancements of software defined network(SDN)and network function virtualization(NFV),service function chain(SFC)placement becomes a crucial enabler for flexible resource scheduling in low earth orbit(LEO)satellite *** due to the scarcity of bandwidth resources and dynamic topology of LEO satellites,the static SFC placement schemes may cause performance degradation,resource waste and even service *** this paper,we consider migration and establish an online migration model,especially considering the dynamic *** the scarcity of bandwidth resources,the model aims to maximize the total number of accepted SFCs while incurring as little bandwidth cost of SFC transmission and migration as *** to its NP-hardness,we propose a heuristic minimized dynamic SFC migration(MDSM)algorithm that only triggers the migration procedure when new SFCs are *** results demonstrate that MDSM achieves a performance close to the upper bound with lower complexity.

关键词： network function virtualization(NFV) resource allocation satellite networks service function chain(SFC) SFC migration SFC placement soft-ware defined network(SDN)

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Distributed adaptive prescribed-time orbit containment control for satellite cluster flight

引用

Chinese Journal of Aeronautics 2024年第8期37卷 342-357页

作者： Tingting ZHANG Shijie ZHANG Huayi LI Xiangtian ZHAO Research Center of satellite Technology Harbin Institute of TechnologyHarbin 150080China State Key laboratory of Networking and Switching Technology Beijing University of Posts and TelecommunicationsBeijing 100876China

The distributed prescribed-time orbit containment control for the satellite cluster flight with multiple dynamic leaders is *** directed information communication topology between followers is taken into account in the overall *** the satellite mass is assumed to be constant,a distributed prescribed-time orbit containment controller is,firstly,presented to drive the followers into the dynamic convex hull produced by multiple ***,the parameter uncertainty is considered,and a prescribed-time sliding mode estimator is introduced to estimate the desired velocity of each *** on the estimated state,a novel distributed adaptive prescribed-time orbit containment control scheme is *** Lyapunov stability theory is utilized to prove the prescribed-time stability of the closed-loop ***,several numerical simulations and comparison of different control methods are provided to verify the effectiveness and superiority of the proposed control method.

关键词： satellite cluster Orbit containment control Prescribed-time control Parameter uncertainty Directed communication graph

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Deep reinforcement learning using least-squares truncated temporal-difference

引用

CAAI Transactions on Intelligence Technology 2024年第2期9卷 425-439页

作者： Junkai Ren Yixing Lan Xin Xu Yichuan Zhang Qiang Fang Yujun Zeng College of Intelligence Science and Technology National University of Defense TechnologyChangshaChina State Key laboratory of Astronautic Dynamics Xi'an Satellite Control CenterXi'anChina

Policy evaluation(PE)is a critical sub-problem in reinforcement learning,which estimates the value function for a given policy and can be used for policy ***,there still exist some limitations in current PE methods,such as low sample efficiency and local convergence,especially on complex *** this study,a novel PE algorithm called Least-Squares Truncated Temporal-Difference learning(LST2D)is *** LST2D,an adaptive truncation mechanism is designed,which effectively takes advantage of the fast convergence property of Least-Squares Temporal Difference learning and the asymptotic convergence property of Temporal Difference learning(TD).Then,two feature pre-training methods are utilised to improve the approximation ability of ***,an Actor-Critic algorithm based on LST2D and pre-trained feature representations(ACLPF)is proposed,where LST2D is integrated into the critic network to improve learning-prediction *** simulation studies were conducted on four robotic tasks,and the corresponding results illustrate the effectiveness of *** proposed ACLPF algorithm outperformed DQN,ACER and PPO in terms of sample efficiency and stability,which demonstrated that LST2D can be applied to online learning control problems by incorporating it into the actor-critic architecture.

关键词： Deep reinforcement learning policy evaluation temporal difference value function approximation

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

欢迎您,

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

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

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

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

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：