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Sensors, systems, and Next-Generation Satellites XXV 2021

作者： Swartz, William H. Krotkov, Nickolay A. Lamsal, Lok N. Otter, Gerard C. J. Van Kempen, Floris Boldt, John D. Morgan, M. Frank Van Der Laan, Ludger Zimbeck, Walter R. Storck, Steven M. Post, Zachary J. Janz, Scott J. Kowalewski, Matthew G. Li, Can Veefkind, J. Pepijn Levelt, Pieternel F. Johns Hopkins University Applied Physics Laboratory 11100 Johns Hopkins Road LaurelMD20723 United States NASA Goddard Space Flight Center GreenbeltMD20771 United States Universities Space Research Association ColumbiaMD21046 United States Stieltjesweg 1 DelftNL-2628 CK Netherlands Earth System Science Interdisciplinary Center University of Maryland 5825 University Research Court Suite 4001 College ParkMD20740 United States Utrechtseweg 297 R and D Satellite Observations De Bilt3731 GA Netherlands University of Technology Delft PO Box 5 Delft2600 AA Netherlands

ISBN: (数字)9781510645615

ISBN: (纸本)9781510645608

Adverse air quality impacts human health and climate and has implications for environmental equity. The Compact Hyperspectral Air Pollution Sensor (CHAPS) is a newly designed small imaging spectrometer for remote sensing of nitrogen dioxide (NO2) and other air pollutants from space. It incorporates two emerging technologies, to achieve the miniaturization necessary to fit within a 6U CubeSat. The first is freeform optics, which can be used to reduce the size of an imaging spectrometer without compromising optical performance. We report the science requirements;preliminary, fully freeform and fully reflective optical design of the CHAPS demonstrator, CHAPS-D;and model its performance. The second technology is additive manufacturing, coupled with topology optimization, which has a number of potential advantages over traditional subtractive manufacturing. The instrument mechanical structure, including optical mounts and integral light baffles, and two of the optical elements will be additively manufactured using a high-strength nextgeneration aluminum alloy. We show preliminary results of additive manufacturing tests. CHAPS-D is currently being developed for ground-based and airborne testing. © COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.

关键词： 3D printers

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Reconfigurable Intelligent Surface Assisted High-Speed Train Communications: Coverage Performance Analysis and Placement Optimization

arXiv

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arXiv 2023年

作者： Liu, Changzhu He, Ruisi Niu, Yong Han, Zhu Ai, Bo Gao, Meilin Ma, Zhangfeng Wang, Gongpu Zhong, Zhangdui The State Key Laboratory of Advanced Rail Autonomous Operation The School of Electronics and Information Engineering The Frontiers Science Center for Smart High-speed Railway System The Beijing Engineering Research Center of High-Speed Railway Broadband Mobile Communications Beijing Jiaotong University Beijing100044 China The State Key Laboratory of Advanced Rail Autonomous Operation Beijing Jiaotong University Beijing100044 China The National Mobile Communications Research Laboratory Southeast University Nanjing211189 China The Department of Electrical and Computer Engineering The University of Houston HoustonTX77004 United States The Department of Computer Science and Engineering Kyung Hee University Seoul446-701 Korea Republic of Henan Joint International Research Laboratory of Intelligent Networking and Data Analysis Zhengzhou University Zhengzhou450001 China Research Center of Networks and Communications Peng Cheng Laboratory Shenzhen China The Tsinghua Space Center the Beijing National Research Center for Information Science and Technology Tsinghua University Beijing100091 China The College of Information Engineering Shaoyang University Shaoyang422000 China The Beijing Key Lab of Transportation Data Analysis and Mining School of Computer and Information Technology Beijing Jiaotong University Beijing100044 China

Reconfigurable intelligent surface (RIS) emerges as maximization problem is formulated to facilitate RIS discrete an efficient and promising technology for the next wireless phase design and RIS placement optimization, which is subject generation networks and has attracted a lot of attention owing to coverage probability constraint. simulation results validate to the capability of extending wireless coverage by reflecting that better coverage performance and higher travel distance signals toward targeted receivers. In this paper, we consider can be achieved with deployment of RIS. The impacts of some a RIS-assisted high-speed train (HST) communication system key system parameters including transmission power, signal-to-to enhance wireless coverage and improve coverage probability. noise ratio threshold, number of RIS elements, number of RIS First, coverage performance of the downlink single-input-single- quantization bits, horizontal distance between base station and output system is investigated, and the closed-form expression RIS, and speed of HST on system performance are investigated. of coverage probability is derived. Moreover, travel distance In addition, it is found that RIS can well improve coverage probability with limited power consumption for HST communications. Copyright © 2023, The Authors. All rights reserved.

关键词： Railroads

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

SSRN

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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 School of Ecology 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

Study region: The Tibetan Plateau in China, the Third Pole of the *** focus: Accurate descriptions of spatial variation in evapotranspiration (ET) and its components on the Tibetan Plateau (TP) are crucial for understanding the dynamics of the regional water cycle and energy balance. However, how various environmental factors affect ET and its components remains unclear. This study addresses this gap using observational data from 14 sites and employing the Shuttleworth-Wallace-Hu (SWH) model to examine the spatial relationships between ET, its components, and underlying *** hydrological insights for the region: The SWH model parameters were optimized using the Monte Carlo method, achieving a satisfactory model performance with an average R² of 0.75. The ratio of transpiration to ET was generally higher in alpine meadows (0.55) than alpine steppes (0.39). Across the TP, precipitation and the leaf area index together shaped spatial variation in ET and transpiration. Precipitation emerged as the primary driver of interannual variation in ET, while the leaf area index strongly regulated the proportion of ET accounted for by transpiration. Furthermore, above aridity index values of 0.73, grassland ecosystems transitioned from water to energy. This finding is significant as it challenges the common application of an aridity index value of 0.65 to distinguish arid from humid regions. It suggests that TP grasslands, with an AI of 0.65-0.73, remain primarily water-limited. © 2024, The Authors. All rights reserved.

关键词： Biotic

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THE TROPICS

引用

BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY 2023年第9期104卷 S207-S269页

作者： Diamond, H. J. Schreck, C. J. NOAA/OAR Air Resources Laboratory College Park Maryland North Carolina State University North Carolina Institute for Climate Studies Cooperative Institute Satellite Earth System Studies Asheville North Carolina NOAA/NWS National Centers for Environmental Prediction Climate Prediction Center College Park Maryland University of Miami Rosenstiel School of Marine and Atmospheric Science Miami Florida NOAA/NWS National Hurricane Center Miami Florida NOAA/OAR Atlantic Oceanographic and Meteorological Laboratory Miami Florida Lamont-Doherty Earth Observatory Columbia University Palisades New York Institute for Climate and Application Research (ICAR)/KLME/ILCEC/CIC-FEMD Nanjing University of Information Science and Technology Nanjing China Centro de Previsão do Tempo e Estudos Climáticos/National Institute for Space Research Center for Weather Forecasts and Climate Studies Cachoeira Paulista Brazil National Institute of Water and Atmospheric Research Ltd. Auckland New Zealand Canadian Hurricane Centre Dartmouth Canada Earth System Modeling Center Nanjing University of Information Science and Technology Nanjing China NOAA/NWS Climate Prediction Center College Park Maryland Department of Atmospheric Science Colorado State University Fort Collins Colorado NOAA/NESDIS Center for Satellite Applications and Research Fort Collins Colorado National Taiwan University Taipei Taiwan Institute for Climate and Application Research Nanjing University of Information Science and Technology Nanjing China Centre for Water Climate and Land School of Environmental and Life Sciences University of Newcastle Callaghan Australia Greater Wellington Regional Council Wellington New Zealand Slovak Hydrometeorological Institute Bratislava Slovakia Australian Bureau of Meteorology Melbourne Australia WeatherTiger Tallahassee Florida School of Ocean and Earth Science and Technology Department of Meteorology University of Hawaii International Pacific Research Center Honolulu Hawaii Department

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Natural image classification based on multi-parameter optimization in deep convolutional neural network

引用

International Journal of Performability Engineering 2019年第9期15卷 2515-2521页

作者： Wang, Lei Zhang, Yanning Xi, Runping Ling, Lu School of Computer Northwestern Polytechnical University Xi'an710072 China National Engineering Laboratory for Integrated Aero-Space-Ground-Ocean Big Data Application Technology Xi'an710072 China Jiangxi Engineering Technology Research Center of Nuclear Geoscience Data Science and System East China University of Technology Nanchang330013 China

Traditional machine learning algorithms cannot adequately train the parameters of networks using massive data. A deep convolutional neural network based on multi-parameter optimization by the TensorFlow deep learning framework is designed in this paper. In order to improve the training speed and prevent over-fitting, we improve and optimize the multi-parameters, including the batch value, dropout, and momentum in the network structure. The experiment involves training and testing on the standard natural image data sets in cifar-10 and cifar-100. The experimental results show that the method achieve better classification accuracy in less time compared with other algorithms, such as Conv-KN, ImageNet-2010, SVM, LR, and Boosting. © 2019 Totem Publisher, Inc. All rights reserved.

关键词： Image classification

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Highly stable and wide-range flexible pressure sensors with a gradient modulus and selective foaming layer

引用

Chemical Engineering Journal 2025年 515卷

作者： Wang, Meng Li, Wendong Lv, Yadong Li, Guangxian Zhao, Zhijun Wang, Yaobing Zhou, Qinghua Pu, Wei Kong, Miqiu School of Aeronautics and Astronautics Key Laboratory of Advanced Spatial Mechanism and Intelligent Spacecraft Ministry of Education National Key Laboratory of Advanced Polymer Materials Sichuan University Chengdu610065 China College of Polymer Science and Engineering National Key Laboratory of Advanced Polymer Materials Sichuan University Chengdu610065 China Beijing Key Laboratory of Intelligent Space Robotic Systems Technology and Applications Beijing Institute of Spacecraft System Engineering Beijing100094 China

The service life and stability of flexible pressure sensors vary with the interfacial toughness of these multilayered structures, which are principally fabricated by adhesive bonding, hot melting, and interconnection. However, balancing the trade-off between interface toughness and sensing performance under complex stresses remains challenging. To address this issue, a foam sandwich structure with gradient modulus is constructed by integrating a thermoplastic polyurethane (TPU)/carbon nanotube electrode with a selectively foamed TPU/ionic liquid dielectric. The synthesis is fundamentally inspired by the molecular chain entanglements and hydrogen bonds formed at the electrode/dielectric interface owing to solvent diffusion due to secondary solubilization and differential foaming temperatures. The synthesized sensing structure exhibits ultra-high toughness (3000 J/m2) and dynamic impact resistance (1 J);meanwhile, the sensor shows an ultra-wide sensing range (0.02–2000 kPa), high sensitivity (1.7 nF/kPa), and excellent service stability up to 50,000 cycles under compressive stress (100 kPa), shear stress (30 kPa), bending stress (bending radius of 1.6 mm), and complex stress of 120 kPa (compression stress of 116 kPa and shear stress of 31 kPa). Additionally, on integration into robot grippers, the sensor provides accurate feedback on multi-stage object gripping and can resist shear stress while gripping high-weight objects. This study provides a new strategy for fabricating flexible pressure sensors that can be effectively used under complex stresses. © 2025 Elsevier B.V.

关键词： Shear bands

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THE MOLECULAR CLOUD LIFECYCLE II: FORMATION AND DESTRUCTION OF MOLECULAR CLOUDS DIAGNOSED VIA H2 FLUORESCENT EMISSION

arXiv

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arXiv 2024年

作者： Burkhart, Blakesley Bialy, Shmuel Seifried, Daniel Walch, Stefanie Hamden, Erika Haworth, Thomas J. Hoadley, Keri Kong, Shuo Johnson, Madisen Jeffreson, Sarah Krumholz, Mark R. Lee, Min-Young Sternberg, Amiel Turner, Neal J. Department of Physics and Astronomy Rutgers University 136 Frelinghuysen Rd PiscatawayNJ08854 United States Center for Computational Astrophysics Flatiron Institute 162 Fifth Avenue New YorkNY10010 United States Physics Department Technion - Israel Institute of Technology Haifa31000 Israel I. Physics Institute University of Cologne Zülpicher Str. 77 Cologne50937 Germany Center for Data and Simulation Science www.cds.unikoeln.de Cologne Germany Steward Observatory University of Arizona TucsonAZ85719 United States Astronomy Unit School of Physics and Astronomy Queen Mary University of London LondonE1 4NS United Kingdom Department of Physics & Astronomy University of Iowa Van Allen Hall Iowa CityIA52242 United States Harvard-Smithsonian Center for Astrophysics 60 Garden Street CambridgeMA United States Research School of Astronomy and Astrophysics Australian National University CanberraACT2600 Australia Korea Astronomy and Space Science Institute 776 Daedeok-daero Daejeon34055 Korea Republic of Department of Astronomy and Space Science University of Science and Technology 217 Gajeong-ro Daejeon34113 Korea Republic of Tel Aviv University P.O. Box 39040 Tel Aviv6997801 Israel Jet Propulsion Laboratory California Institute of Technology PasadenaCA91109 United States

Molecular hydrogen (H2) formation and dissociation are key processes that drive the gas lifecycle in galaxies. Using the SImulating the LifeCycle of Molecular Clouds (SILCC) zoom-in simulation suite, we explore the utility of future observations of H2 dissociation and formation for tracking the lifecycle of molecular clouds. The simulations used in this work include non-equilibrium H2 formation, stellar radiation, sink particles, and turbulence. We find that, at early times in the cloud evolution, H2 formation rapidly outpaces dissociation and molecular clouds build their mass from the atomic reservoir in their environment. Rapid H2 formation is also associated with a higher early star formation rate. For the clouds studied here, H2 is strongly out of chemical equilibrium during the early stages of cloud formation but settles into a bursty chemical steady-state about 2 Myrs after the first stars form. At the latest stage of cloud evolution, dissociation outweighs formation and the clouds enter a dispersal phase. We discuss how theories for the molecular cloud lifecycle and the star formation efficiency may be distinguished with observational measurements of H2 fluorescence with a space-based high-resolution FUV spectrometer, such as the proposed Hyperion and Eos NASA Explorer missions. Such missions would enable measurements of the H2 dissociation and formation rates, which we demonstrate can be connected to different phases in a molecular cloud’s star-forming life, including cloud building, rapidly star-forming, H2 chemical equilibrium, and cloud destruction. © 2024, CC BY.

关键词： Dissociation

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Two Efficient Beamforming Methods for Hybrid IRS-aided AF Relay Wireless Networks

arXiv

引用

arXiv 2023年

作者： Wang, Xuehui Shu, Feng Huang, Mengxing Zhou, Fuhui Chen, Riqing Pan, Cunhua Wu, Yongpeng Wang, Jiangzhou The School of Information and Communication Engineering Hainan University Haikou570228 China The School of Information and Communication Engineering and Collaborative Innovation Center of Information Technology Hainan University Haikou570228 China The School of Electronic and Optical Engineering Nanjing University of Science and Technology Nanjing210094 China The College of Electronic and Information Engineering Nanjing University of Aeronautics and Astronautics Nanjing210000 China The Key Laboratory of Dynamic Cognitive System of Electromagnetic Spectrum Space Nanjing University of Aeronautics and Astronautics Nanjing210000 China The Ministry of Industry and Information Technology Nanjing211106 China The Digital Fujian Institute of Big Data for Agriculture Fujian Agriculture and Forestry University Fuzhou350002 China National Mobile Communications Research Laboratory Southeast University Nanjing211111 China The Shanghai Key Laboratory of Navigation and Location Based Services Shanghai Jiao Tong University Minhang200240 China The School of Engineering University of Kent CanterburyCT2 7NT United Kingdom

Due to the "double fading" effect caused by conventional passive intelligent reflecting surface (IRS), the signal via the reflection link is weak. To enhance the received signal, active elements with the ability to amplify the reflected signal are introduced to the passive IRS forming hybrid IRS. In this paper, we propose a hybrid IRS-aided amplify-and-forward (AF) relay wireless network, where an optimization problem is formulated, which is subject to the constraints of transmit power budgets at the source/AF relay/hybrid IRS and that of unit modulus for passive IRS elements. By alternately designing the beamforming matrix at AF relay and the reflecting coefficient matrices at IRS, signal-to-noise ratio can be maximized. To achieve high rate performance and extend the coverage range, a high-performance method based on semidefinite relaxation and fractional programming (HP-SDR-FP) algorithm is presented. Due to its extremely high complexity, a low-complexity method based on whitening filter, general power iterative and generalized Rayleigh-Ritz (WF-GPI-GRR) is proposed, which is different from HP-SDR-FP method. It is assumed that the amplifying coefficient of each active IRS element is equal, and the corresponding analytical solution of the amplifying coefficient can be obtained according to the transmit powers at AF relay and hybrid IRS. simulation results show that the proposed two methods can greatly improve the rate performance compared to the existing networks, such as the passive IRS-aided AF relay and only AF relay network. In particular, a 50.0% rate gain over the existing networks is approximately achieved in the high power budget region of hybrid IRS. Moreover, it is verified that the proposed HP-SDR-FP method perform better than WF-GPI-GRR method in terms of rate performance. Copyright © 2023, The Authors. All rights reserved.

关键词： Wireless networks

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Learning a faster locomotion gait for a quadruped robot with model-free deep reinforcement learning

Learning a faster locomotion gait for a quadruped robot with...

引用

2019 IEEE International Conference on Robotics and Biomimetics, ROBIO 2019

作者： Hu, Biao Shao, Shibo Cao, Zhengcai Xiao, Qing Li, Qunzhi Ma, Chao Beijing University of Chemical Technology College of Information Science and Technology Beijing100029 China Beijing Institute of Spacecraft System Engineering Beijing Key Laboratory of Intelligent Space Robotic Systems Technology and Applications Beijing China

ISBN: (纸本)9781728163215

Quadruped robots have great agility, flexibility and stability, which enables them to walk through uneven terrain. Motion control of legged robots is always a difficult problem. Previous approaches mostly either use a predefined gait that results in clumsy and unnatural behavior, or use reinforcement learning approach to generate a gait strategy that needs longtime computation and elegant network design. In this paper, we present an effective approach that uses deep reinforcement learning with prior knowledge to optimize the gait of quadruped robot. By using a specific quadruped robot walking gait as a priori knowledge, this approach adopts the technique of distributed proximal policy optimization to optimize the search for better gait. The proposed approach does not require modelling of complex robots, and has good network convergence speed and learning effect. simulation results demonstrate that our proposed approach converges faster than other deep reinforcement learning methods without prior knowledge. Besides, our achieved gait has higher speed that is 50% faster than the trot gait without optimization. © 2019 IEEE.

关键词： Reinforcement learning

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A Microservices Oriented Edge Computing Framework for LVC simulation in the IoT Era

A Microservices Oriented Edge Computing Framework for LVC Si...

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2019第十一届计算机建模与仿真国际会议

作者： Wenxin Sun Yanlong Zhai Tianhong Bao Muhammad Mudassar Jun Shen Kai Yang School of Computer Science Beijing Institute of Technology School of Computing & Information Technology University of Wollongong Science and Technology on Special System Simulation Laboratory Beijing Simulation Center

Modeling and simulation are essential methods to better understand a complex system in the real world. Many simulation systems have strong demand for involving physical devices or equipment in the system to improve the fidelity. But most of the current cloud based simulation systems are designed for equipment with adequate resources and suffering from high latency for their centralized communication. Edge computing is getting much attention as a new paradigm for distributed systems involving heterogeneous devices and requiring real-time communication. However, edge computing is still in its initial stage and there is no consensus on the edge framework and implementation. To the best of our knowledge, no detailed studies have explored the edge-side simulation and modeling. In this paper, we study and design an edge-side simulation framework, which exploits light-weight microservices architecture to build scalable and real-time LVC(Live, Virtual and Constructive) simulations. Specifically, the application model is designed to illustrate how LVC simulation integrates with edge computing and cloud computing. The autonomous negotiation service and time synchronization services are discussed in details. Though it is a preliminary edge computing framework for LVC simulation, no similar research has been conducted for modeling and simulation using edge computing.

关键词： Edge-side simulation microservices LVC simulation IoT

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