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Rydberg electromagnetically induced transparency and absorption of strontium triplet states in a weak microwave field

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Physical Review A 2022年第5期105卷 053714-053714页

作者： Yan-Li Zhou Dong Yan Weibin Li Department of Physics College of Liberal Arts and Sciences and Interdisciplinary Center for Quantum Information National University of Defense Technology Changsha 410073 China School of Science and Key Laboratory of Materials Design and Quantum Simulation Changchun University Changchun 130022 China School of Physics and Astronomy and Centre for the Mathematics and Theoretical Physics of Quantum Non-equilibrium Systems University of Nottingham Nottingham NG7 2RD United Kingdom

We study theoretically laser excitation of Rydberg triplet states of strontium atoms in the presence of weak microwave (MW) fields. Starting from the ground state 5s21S0, the Rydberg excitation is realized through the metastable, triplet 5s5p3P1 state, whose decay rate γ2 is 2π×7.5 kHz, much smaller than the one in the singlet state or alkali-metal atoms. The influences of γ2 on the transparency and absorption spectrum in the electromagnetically induced transparency (EIT), and electromagnetically induced absorption (EIA) regime are examined. Narrow transparent windows (EIT) or absorption peaks (EIA) are found, whose distance in the spectrum depends on the Rabi frequency of the weak MW field. It is found that the spectrum exhibits higher contrast than using the singlet state or alkali-metal atoms in typical situations. Using the metastable intermediate state, we find that the resonance fluorescence of Sr gases exhibits very narrow peaks, which are modulated by the MW field. When the MW field is weaker than the probe and control light, the spectrum distance of these peaks is linearly proportional to Ωm. This allows us to propose an alternative way to sense very weak MW fields through resonance fluorescence. Our study shows that the Sr triplet state could be used to develop the Rydberg MW electrometry that gains unique advantages.

关键词： Light-matter interaction Quantum metrology Quantum optics

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Single-Dimensional Intuitive teaching Control for Constrained space Robotic Manipulation

Single-Dimensional Intuitive teaching Control for Constraine...

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IEEE International Conference on Robotics and Biomimetics

作者： Hang Gao Xiaodong Zhang Huanbin Xu Tao Xiao Chao Ma School of Mechanical Engineering University of Science and Technology Beijing Beijing China Beijing Key Laboratory of Intelligent Space Robotic Systems Technology and Application Beijing Institute of Spacecraft System Engineering Cast China

ISBN: (纸本)9781665405362

In this paper, a single-dimensional intuitive teaching algorithm for space robots is proposed to solve the motion control problem when the operating space is limited or the moving direction is relatively special under complex space environments. More precisely, the developed method can specify the direction and reaches the specified position under the drag motion of the hand. The realization algorithm of single-dimension intuitive teaching is derived according to the structure of the robot. In the end, an experiment example is given, which proves the feasibility of the proposed algorithm.

关键词： Robot kinematics Education Aerospace electronics Robot sensing systems Sensor systems Sensors Reliability

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Performance Evaluations for RIS-Aided Satellite Aerial Terrestrial Integrated Networks with Link Selection Scheme and Practical Limitations

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IEEE Transactions on Network and Service Management 2024年

作者： Zhou, Feng Guo, Kefeng Huang, Gaojian Li, Xingwang Markakis, Evangelos K. Politis, Ilias Asif, Muhammad Yancheng Institute of Technology School of Information Technology Yancheng224051 China Nanjing University of Aeronautics and Astronautics College of Electronic and Information Engineering Nanjing210016 China Space Engineering University School of Space Information Beijing101407 China Henan Polytechnic University School of Physics and Electronic Information Engineering Jiaozuo454000 China Southeast University National Mobile Communications Research Laboratory Nanjing210096 China Hellenic Mediterranean University Electrical and Computer Engineering Department Heraklion71410 Greece Industrial Systems Institute / Research Center 'ATHENA' Patras26504 Greece InQbit Innovations Srl Bucharest041386 Romania Jiangsu University School of Computer Science and Communication Engineering Zhenjiang China

This paper researches the system evaluations of the reconfigurable intelligent surface (RIS)-assisted satellite aerial terrestrial integrated systems. To ensure the stability of the regarded network, a link selection scheme is presented to get the balance between the system performance and the system efficiency. Besides, in order to build a practical environment of the transmission networks, the imperfect hardware, channel estimation errors and co-channel interference are both considered in the networks. Relied on the above considerations, the detailed analysis for the outage behaviors is shown along with the asymptotic outage probability in high signal-to-noise ratio scenarios. Moreover, the diversity order and coding gain are also provided to give fast methods to confirm the system evaluation. Finally, some re-presentative simulations are provided to confirm the efficiency and advantage of analytical results and the proposed link selection scheme. © 2004-2012 IEEE.

关键词： Signal to noise ratio

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An Interacting-Multiple-Model Method for Tracking a Hypersonic Glide Target

An Interacting-Multiple-Model Method for Tracking a Hyperson...

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Chinese Control and Decision Conference, CCDC

作者： Jingshuai Huang Hongbo Zhang Shang Wu Guojian Tang Weimin Bao National University of Defense Technology College of Aerospace Science and Engineering Changsha China Science and Technology on Complex Aviation Systems Simulation Laboratory Beijing

ISBN: (数字)9781728158556

ISBN: (纸本)9781728158563

In terms of tracking a hypersonic glide target (HGT), a tracking method is proposed based on interacting-multiple-model (IMM). Target tracking mainly contains two missions: system modeling and choosing filtering algorithm. First, a tracking system is established composed of state and measurement equations on basis of ground-based radar measuring. The Singer model is used to represent the unknown aerodynamic acceleration. Then, to enhance model adaptation of the tracking method, three-model interacting filter is constructed with maneuver-frequency adaption based on unscented Kalman filter (UKF). Through tracking a flight trajectory generated by Gauss Pseudospectral Method, the effectiveness of the proposed method is validated and the multiple-model is superior to the single-model.

关键词： Target tracking Radar tracking Electronic mail Kalman filters Adaptation models Mathematical model Aerospace engineering

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Corrigendum to “Boric acid-regulated gelation and ethanol-assisted preparation of polybenzoxazine aerogels” [Chem. Eng. J. 486 (2024) 150228]

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Chemical Engineering Journal 2025年 506卷

作者： Jinlong Zhou Yunyun Xiao Saihui Liu Zeyu Li Xinyi Liu Sizhao Zhang Zhengquan Li International Institute for Innovation Jiangxi University of Science and Technology Nanchang 330013 PR China Jiangxi Provincial Key Laboratory for Simulation and Modelling of Particulate Systems Nanchang 330013 PR China School of Energy and Mechanics Jiangxi University of Science and Technology Nanchang 330013 P.R. China

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Unmanned Marine Emergency Response System technology

Unmanned Marine Emergency Response System Technology

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2019 IEEE International Conference on Unmanned systems, ICUS 2019

作者： Zhang, Hongli Song, Yuanyun Chen, Chao Chu, Xianying Beijing Aerospace Technology Research Institute Beijing China Aviation Systems Simulation Laboratory Science and Technology on Complex Beijing China

ISBN: (纸本)9781728137926

With the global climate change, the frequency and destructiveness of emergencies in the coastal areas worldwide have increased in recent years. The rapid response of the existing equipment and means is insufficient. It is urgent to improve response speed for marine research, disaster investigation, marine rescue, maritime surveillance and other maritime emergencies. With the development of high-speed civil aircraft technology, the high-speed UAV platform can form an unmanned emergency response system, taking advantage of fast arrival, wide coverage and flexibility. The simulation shows that the unmanned emergency system has outstanding advantages compared with the existing subsonic UAV, and can effectively execute emergency marine missions. © 2019 IEEE.

关键词： Unmanned aerial vehicles (UAV)

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Rapid Automated Mapping of Clouds on Titan With Instance Segmentation

arXiv

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arXiv 2025年

作者： Yahn, Zachary Trent, Douglas M. Duncan, Ethan Seignovert, Benoît Santerre, John Nixon, Conor A. School of Computer Science Georgia Institute of Technology AtlantaGA United States Planetary Systems Laboratory NASA Goddard Space Flight Center GreenbeltMD United States Informatio Data & Analytics Services NASA Langley Research Center HamptonVA United States School of Information University of California Berkeley BerkeleyCA United States Observatoire des Sciences de l'Univers Nantes Atlantique Osuna UAR Nantes3281 France

Despite widespread adoption of deep learning models to address a variety of computer vision tasks, planetary science has yet to see extensive utilization of such tools to address its unique problems. On Titan, the largest moon of Saturn, tracking seasonal trends and weather patterns of clouds provides crucial insights into one of the most complex climates in the Solar System, yet much of the available image data are still analyzed in a conventional way. In this work, we apply a Mask R-CNN trained via transfer learning to perform instance segmentation of clouds in Titan images acquired by the Cassini spacecraft-a previously unexplored approach to a "big data" problem in planetary science. We demonstrate that an automated technique can provide quantitative measures for clouds, such as areas and centroids, that may otherwise be prohibitively time‐intensive to produce by human mapping. Furthermore, despite Titan‐specific challenges, our approach yields accuracy comparable to contemporary cloud identification studies on Earth and other worlds. We compare the efficiencies of human‐driven versus algorithmic approaches, showing that transfer learning provides speed‐ups that may open new horizons for data investigation for Titan. Moreover, we suggest that such approaches have broad potential for application to similar problems in planetary science where they are currently under‐utilized. Future planned missions to the planets and remote sensing initiatives for the Earth promise to provide a deluge of image data in the coming years that will benefit strongly from leveraging machine learning approaches to perform the analysis. © 2025, CC BY.

关键词： Image segmentation

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

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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 grain level model for deformation and failure of ultrafine-grained tungsten

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science China(Technological sciences) 2019年第5期62卷 755-761页

作者： REN Ke CHEN LiRong CHENG YangYang WANG JianXiang DUAN HuiLing State Key Laboratory for Turbulence and Complex Systems Department of Mechanics and Engineering Science College of EngineeringPeking University Key Laboratory of High Energy Density Physics Simulation Center of Applied Physics and Technology BIC-ESAT and IFSA Collaborative Innovation Center of MoE Peking University

Ultrafine-grained tungsten(UFG W) produced by severe plastic deformation technology has many potential applications due to its high strength and ductility. To reveal the mechanism for the high ductility of UFG W, the deformation and failure behaviors of coarse-grained tungsten(CG W) and UFG W have been compared based on a three-dimensional crystal plastic finite element method(CPFEM) simulation. Cohesive element method has been utilized to model the behavior of grain boundaries(GBs). Both plastic deformation in grain interiors and grain boundary opening have been observed in different periods of deformation in UFG W. It is concluded that the high GB density and elongated microstructure in the UFG W suppress crack propagation, decrease the stress concentration and impurity concentration on GBs, therefore enhance the ductility of the material.

关键词： ultrafine grain(UFG) tungsten crystal plasticity interface failure

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Forest or grassland? A quantitative analysis of urban residents' green exposure preference by using multi-temporal mobile signal data

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Urban Forestry and Urban Greening 2025年 108卷

作者： Geng, Hongkai Lin, Tao van Bodegom, P.M. Hu, Mingming Zheng, Yicheng Jia, Zixu Zhang, Junmao Guo, Xiangzhong Chen, Yuan Lin, Meixia Cai, Jiayu Lin, Jing Key Laboratory of Urban Environment and Health Institute of Urban Environment Chinese Academy of Sciences Xiamen 361021 China University of Chinese Academy of Sciences Beijing 100049 China Fujian Key Laboratory of Digital Technology for Territorial Space Analysis and Simulation Fuzhou 350108 China State Key Laboratory of Regional and Urban Ecology Institute of Urban Environment Chinese Academy of Sciences Xiamen 361021 China Institute of Environmental Sciences (CML) Leiden University Leiden Netherlands School of Geographical Sciences Faculty of Science and Engineering University of Nottingham Ningbo 315100 China School of Architecture and Urban-Rural Planning Fuzhou University Fuzhou 350108 China

Urban forests and grasslands provide diverse services from their unique characteristics. Optimizing green spaces by understanding urban residents’ preferences is a critical challenge for sustainable city development amid limited land resources. However, the mechanism influencing exposure across various types of green remains unclear. This study utilized multi-temporal mobile signal data from Shanghai to quantify the exposure intensity (EI) and density (ED) for forests and grasslands. These metrics addressed the gap by revealing spatiotemporal variations in exposure preference (EP) and related socioeconomic influences. Specifically, the study addressed two key questions: (1) Do urban residents exhibit preferences between forests and grasslands in terms of EI and ED? (2) How do socioeconomic features influence these preferences? Results showed: (1) Forests had almost double the annual EI (542.86 p/h) and ED (2.69 p/m²/h) of grasslands (P < 0.001). However, grasslands in central regions exhibited significantly higher ED (13.60 vs. 11.83 p/m²/h;P < 0.001). (2) Commercial House (34.4 % importance) and Sports & Recreation (15.7 %) maximized green exposure, while Road Furniture reduced it. (3) Evening exposure peaks in central regions extended by 1 hour due to commercial-cultural synergies. Forest ED, highly driven by Commercial House, clustered in central cores and specific non-central communities, whereas Road Furniture most negatively impacted central periphery communities. These findings directly inform differentiated urban planning strategies: forests should prioritize improving accessibility to sustain prolonged exposures, while grasslands need spatial optimization to accommodate peak social demand. By aligning green space planning with socioeconomic drivers, cities can enhance the effectiveness of their service under land constraints. © 2025 Elsevier GmbH

关键词： Exposure preference Green exposure Machine learning Multi-scale geographically weighted regression Urban green space

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