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Estimation of Sensible and Latent Heat Flux Over Mountainous Areas Using the SEBAL Model

IEEE Transactions on Geoscience and Remote Sensing 2025年 63卷

作者： Wei Fu Bo-Hui Tang Xianguang Ma Dong Fan Xinming Zhu Faculty of Land Resource Engineering Kunming University of Science and Technology Kunming China Yunnan Key Laboratory of Quantitative Remote Sensing Kunming China Yunnan International Joint Laboratory for Integrated Sky-Ground Intelligent Monitoring of Mountain Hazards Kunming China State Key Laboratory of Resources and Environment Information System Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing China Planning and Design Institute of Land and Resources of Yunnan Province Kunming China

Accurately estimating sensible heat (H) and latent heat (LE) in mountainous areas is a significant challenge due to the influence of complex topography factors. Currently, most models have been developed to estimate surface heat flux for flat surfaces without considering the effect of complex geometric terrain structures. In this study, the surface energy balance algorithm for land (SEBAL) coupled with a mountainous net surface radiation ( $R_{n}$ ) calculation method (MSEBAL) was proposed to accurately estimate H and LE in the upstream catchment regions of the Heihe River Basin (HRB). $R_{n}$ was estimated by correcting the solar incoming radiation components using topographic factors, including slope, aspect, sky view factor (SVF), and terrain configuration factor (TCF). The SEBAL and MSEBAL models were applied to satellite remote sensing (RS) data from Landsat 8 images and ground-observed datasets. In situ measurements from the eddy covariance (EC) system of the A’rou superstation were used to validate the estimation accuracy of $R_{n}$ , LE, and H by MSEBAL. The results show that $R_{n}$ , LE, and H estimated by the MSEBAL exhibit good consistency with the validation of in situ measurements. $R_{n}$ estimated by MSEBAL showed a decrease in RMSE from 164.32 to 51.31 W/m2 and a reduction in absolute bias from 154.50 to 10.50 W/m2 compared to SEBAL. The H and LE estimated by MSEBAL exhibit low RMSE and bias, with values of 31.96 and −17.93 W/m2 for H, and 35.67 and −6.18 W/m2 for LE, respectively, compared to SEBAL. The spatial pattern of surface heat fluxes exhibited variations with complex terrain changes. H and LE were found to be higher at mountain peaks, while lower values were observed in valleys. Additionally, H and LE were greater on east- and south-facing slopes that receive more solar radiation compared to west- and north-facing slopes. This study provides an effective tool for estimating surface heat fluxes over mountainous regions.

关键词： Surface topography Heating systems Land surface Estimation Surfaces Remote sensing Monitoring Land surface temperature Data models Mathematical models

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Limit-Cycle-Based design of Formation Control for Mobile Agents

Limit-Cycle-Based Design of Formation Control for Mobile Age...

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作者： Wang, Chen Xia, Weiguo Xie, Guangming National Engineering Research Center for Software Engineering Key Lab. of Intelligent Control and Optimization for Industrial Equipment of Ministry of Education School of Control Science and Engineering Dalian University of Technology Dalian116024 China State Key Laboratory of Turbulence and Complex Systems Intelligent Biomimetic Design Lab College of Engineering Peking University Beijing China

In this article, we study the formation problem for a group of mobile agents in a plane, in which the agents are required to maintain a distribution pattern, as well as to rotate around or remain static relative to a static/moving target. The prescribed distribution pattern is a class of general formations where the distances between neighboring agents or the distances between each agent and the target do not need to be equal. Each agent is modeled as a double integrator and can merely perceive the relative information of the target and its neighbors, and the acceleration of the target. In order to solve the formation problem, a limit-cycle-based controller design is delivered. We divide the overall control objective into two subobjectives, where the first is target circling that each agent keeps its own desired distance to the static/moving target as well as rotating around or remaining static relative to the target as expected, and the second is distribution adjustment that each agent maintains the desired distance to its neighbors. Then, we propose a controller comprised of two parts, where a limit cycle oscillator named a converging part is designed to deal with the first subobjective, while a layout part is introduced to address the second subobjective. One key merit of the controller is that it can be implemented by each agent in its local frame so that only local information is utilized without knowing global information. Theoretical analysis of the convergence to the desired formation, of which the agents are required to be evenly distributed on a circle around the target, is provided for the multiagent system under the proposed controller. Numerical simulations are given to validate the effectiveness of the proposed controller for the cases of general formations, and to show that no collision between agents ever takes place throughout the system's evolution. © 1963-2012 IEEE.

关键词： Multi agent systems

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An FPGA-based HF/VHF/UHF integrated self-interference cancellation system

An FPGA-based HF/VHF/UHF integrated self-interference cancel...

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2019 Joint International Symposium on Electromagnetic Compatibility, Sapporo and Asia-Pacific International Symposium on Electromagnetic Compatibility, EMC Sapporo/APEMC 2019

作者： Xing, Jinling Liu, Yongcai Ge, Songhu Li, Yi Meng, Jin National Key Laboratory of Science and Technology on Vessel Integrated Power System Naval University of Engineering Wuhan Hubei Province430033 China

ISBN: (纸本)9784885523229

The paper describes the design and performance of an FPGA-based interference cancellation system operating in the 2MHz-500MHz frequency band. The system adopts the RF direct bandpass sampling structure without down-converter introduced. The paper lays stress on the analysis and demonstration of feasibility and design consideration of bandpass sampling technique in the cancellation system, and presents the high speed FPGA realization of the low pass filter - a key module of the adaptive correlation algorithm. Experimental results show that average 64.2dB and 61.8dB suppression are achieved for the ideal sine-wave signal interference and amplitude-modulated signal interference, respectively, presenting an excellent cancellation performance of the proposed system. © 2019 The Institute of Electronics, Information and Communication Engineer.

关键词： Field programmable gate arrays (FPGA)

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Effect of finned structure on critical heat flux (CHF) in downward-face pool boiling 27

Effect of finned structure on critical heat flux (CHF) in do...

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27th International Conference on Nuclear Engineering: Nuclear Power Saves the World!, ICONE 2019

作者： Wang, Kai Erkan, Nejdet Cai, Rong Okamoto, Koji Department of Nuclear Engineering and Management School of Engineering University of Tokyo Tokyo Japan Science and Technology on Reactor System Design Technology Laboratory Chengdu China Nuclear Professional School School of Engineering University of Tokyo Tokyo Japan

ISBN: (纸本)9784888983051

CHF plays an important role in the heat transfer process during the external reactor vessel cooling (IVR-ERVC) which is deemed as a very effective way to release the decay heat after the core melted. In this paper, the experiment of the macro-fin structure experiment positioned on slope that is declined at angles of 5°and 10°was done. The results of the copper bar experiment were then analyzed and compared with the results obtained from a copper block experiment that had been conducted previously at the same test facility, and it was found that the CHF decreased. Finally, the hot/dry spot theory for the copper bar was brought up in an attempt to explain the difference of copper and copper bar. It seemed that using this theory can explain the decrease of CHF for copper bar. Copyright © 2018-2019 by JSME

关键词： Heat flux

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Kinematic, Workspace and Force Analysis of a five-DOF Hybrid Manipulator R(2RPR)R/SP+RR

Research Square

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Research Square 2021年

作者： Xu, Yundou Yang, Fan Mei, Youen Zhang, Dongsheng Zhou, Yulin Zhao, Yongsheng Laboratory of Parallel Robot and Mechatronic System of Hebei Province Yanshan University Qinhuangdao066004 China Key Laboratory of Advanced Forging & Stamping Technology Science of Ministry of National Education Yanshan University Qinhuangdao006004 China School of Mechanical Engineering Yanshan University Qinhuangdao066004 China Tencent Robotics X Tencent Holdings Shenzhen518057 China

In the present study, the over-constrained hybrid manipulator R(2RPR)R/SP+RR is considered as the research objective. In this paper, kinematics of the hybrid manipulator, including the forward and inverse position, are analyzed. Then, the workspace is checked based on the inverse position solution to evaluate whether the workspace of the hybrid manipulator meets the requirements, and the actual workspace of the hybrid robot is analyzed. After that, the force analysis of the over-constrained parallel mechanism is carried out, and an ADAMS-ANSYS rigid-flexible hybrid body model is established to verify the simulation. Based on the obtained results from the force analysis, the manipulator structure is design. Then, the structure optimization is carried out to improve the robot stiffness. Finally, calibration and workspace verification experiments are performed on the prototype, cutting experiment of an S-shaped aluminum alloy workpiece is completed, and the experiment verifies the processing ability of the prototype and proves that the prototype has good application prospects. © 2021, CC BY.

关键词： Kinematics

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Tri-Polarized Holographic MIMO Surface in Near-Field: Channel Modeling and Precoding design

arXiv

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arXiv 2022年

作者： Wei, Li Huang, Chongwen Alexandropoulos, George C. Yang, Zhaohui Yang, Jun Sha, Wei E.I. Zhang, Zhaoyang Debbah, Mérouane Yuen, Chau Pillar Singapore University of Technology and Design 487372 Singapore College of Information Science and Electronic Engineering Zhejiang University Hangzhou310027 China International Joint Innovation Center Zhejiang University Haining314400 China Hangzhou310027 China The Department of Informatics and Telecommunications National and Kapodistrian University of Athens Panepistimiopolis Ilissia Athens15784 Greece The Technology Innovation Institute Abu Dhabi United Arab Emirates The State Key Laboratory of Mobile Network and Mobile Multimedia Technology Shenzhen518055 China Wireless Product R&D Institute ZTE Corporation Shenzhen518057 China The College of Information Science and Electronic Engineering Zhejiang University Hangzhou310027 China The Technology Innovation Institute Masdar City Abu Dhabi9639 United Arab Emirates CentraleSupelec University Paris-Saclay Gif-sur-Yvette91192 France

This paper investigates the utilization of triple polarization (TP) for multi-user (MU) holographic multiple-input multi-output surface (HMIMOS) wireless communication systems, targeting at capacity boosting and diversity exploitation without enlarging the antenna array sizes. We specifically consider that both the transmitter and receiver are both equipped with an HMIMOS consisting of compact sub-wavelength TP patch antennas within near-field (NF) regime. To characterize TP MU-HMIMOS systems, a TP NF channel model is constructed using the dyadic Green’s function, whose characteristics are leveraged to design two precoding schemes for mitigating the cross-polarization and inter-user interference contributions. Specifically, a user-cluster-based precoding scheme assigns different users to one of three polarizations at the expense of system’s diversity, and a two-layer precoding scheme removes interference using Gaussian elimination method at high computational cost. The theoretical correlation analysis for HMIMOS in NF region is also investigated, revealing that both the spacing of transmit patch antennas and user distance impact transmit correlation factors. Our numerical results show that the users far from transmit HMIMOS experience higher correlation than those closer within NF regime, resulting in a lower channel capacity. Meanwhile, in terms of channel capacity, TP HMIMOS can almost achieve 1.25 times gain compared with dual-polarized HMIMOS, and 3 times compared with conventional HMIMOS. In addition, the proposed two-layer precoding scheme combined with two-layer power allocation realizes a higher spectral efficiency than other schemes without sacrificing diversity. Copyright © 2022, The Authors. All rights reserved.

关键词： Polarization

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Microscopic Origin of Capillary Force Balance at Contact Line

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Physical Review Letters 2020年第12期124卷 125502-125502页

作者： JingCun Fan Joël De Coninck HengAn Wu FengChao Wang CAS Key Laboratory of Mechanical Behavior and Design of Materials Department of Modern Mechanics CAS Center for Excellence in Complex System Mechanics University of Science and Technology of China Hefei 230027 China Laboratory of Surface and Interfacial Physics (LPSI) University of Mons 7000 Mons Belgium

We investigate the underlying mechanism of capillary force balance at the contact line. In particular, we offer a novel approach to describe and quantify the capillary force on the liquid in coexistence with its vapor phase, which is crucial in wetting and spreading dynamics. Its relation with the interface tension is elucidated. The proposed model is verified by our molecular dynamics simulations over a wide contact angle range. Differences in capillary forces are observed in evaporating droplets on homogeneous and decorated surfaces. Our findings not only provide a theoretical insight into capillary forces at the contact line, but also validate Young’s equation based on a mechanical interpretation.

关键词： Capillary interactions Wetting Liquid-solid interfaces

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Re-Recognizing Fluorescence Quenching Units: Improve Abnormally the Luminescent Efficiency of AIEgens for Fluorescence Sensing, Organelle Targeted Imaging and Photodynamic Therapy

SSRN

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SSRN 2022年

作者： Teng, Muzhou Tong, Jialin Xie, Yili Li, Yumin Li, Zhijia Shan, Guoguang Li, Yin Wan, Qing Wang, Zhiming Liu, Tao The Second Clinical Medical College ofLanzhou University Lanzhou University Second Hospital Key Laboratory of the Digestive System Tumors of Gansu Province Lanzhou China College of Ecology and Environment Yuzhang Normal University Nanchang330103 China Institute of Functional Material Chemistry and National & Local United Engineering Lab for Power Battery Faculty of Chemistry Northeast Normal University Changchun China Molecular Diagnosis and Treatment Center for Infectious Diseases Dermatology Hospital Southern Medical University Guangzhou510091 China School of Materials Science and Engineering Nanchang Hangkong University Nanchang330063 China State Key Laboratory of Luminescent Materials and Devices Guangdong Provincial Key Laboratory of Luminescence from Molecular Aggregates Center for Aggregation-induced emission South China University of Technology Guangzhou510640 China

Fluorescence quenching phenomenon caused by the heavy atom effect and intramolecular charge transfer (ICT) is a classical and generally recognized photophysical phenomenon. However, its universality is not observed in some special aggregation-induced emission luminogens (AIEgens). Herein, a series of cyanostyrene (CST)-based AIEgens were designed and synthesized by coupling different electronic donors and fluorescent quenching groups at both ends of the CST "bridge". By clear study of structure-properties relationship of materials, the performance of full-wavelength emission from deep blue to far red could be achieved by regulating the excited state. Intriguingly, grafting fluorescent quenching groups of bromine (Br) atom and nitro (NO2) to CSTs resulted in abnormal fluorescence enhancement, which broke the conventional rule of quenching fluorescence brought from the above-mentioned quenching units. In addition, the introduction of quenching groups was beneficial for boosting reactive oxygen species (ROS) generation because of activating intersystem crossing (ISC) channel to produce triplet excitons, effectively. In view of special chemical structure contained alkaline group as well as clear photophysical performances, some representative CST-based emitters were chosen to explore advanced applications such as information encryption, fluorescent sensor chips of detecting hydrogen chloride and biological amines, target simultaneously fluorescent imaging of cellular lysosome and mitochondria, and effective photodynamic therapy (PDT) to treat cancer cells. This work revealed that conventional rule of heavy atom effect and strong ICT effect to quench fluorescence was not suitable for some unique CST-based AIEgens, which played important role in liberating our inherent cognition to design novel special functional materials in the future. © 2022, The Authors. All rights reserved.

关键词： Charge transfer

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Stability and energetics of two-dimensional surface crystals in liquid AuSi thin films and nanoscale droplets

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Physical Review Materials 2021年第7期5卷 074003-074003页

作者： Hailong Wang Mengyuan Wang Alireza Shahabi Alain Karma Moneesh Upmanyu CAS Key Laboratory of Mechanical Behavior and Design of Materials Department of Modern Mechanics CAS Center for Excellence in Complex System Mechanics University of Science and Technology of China Hefei Anhui 230027 China Group for Simulation and Theory of Atomic-Scale Material Phenomena (stAMP) Department of Mechanical and Industrial Engineering Northeastern University Boston Massachusetts 02115 USA Department of Physics Northeastern University Boston Massachusetts 02115 USA

We employ atomic-scale computational frameworks to study the surface crystallization in AuSi films and droplets as a function of composition, temperature, and size. Above the melting point, the surfaces of both thin films and droplets undergo a first-order transition from a two-dimensional (2D) Au2Si crystalline phase to a laterally disordered yet stratified layer. The thin film surfaces exhibit an effective surface tension that increases with temperature and decreases with Si concentration, while for droplets in the size range 10–30 nm, the bulk Laplace pressure alters the surface segregation as it occurs with respect to a strained bulk. Above the transition, the size effect on the surface tension due to the stratified surface layer is small, while the crystalline surface layer below the transition is strained and composed of 2D crystallites separated by extended grain boundary scars that lead to large fluctuations in its energetics. As a specific application, all-atom simulations of AuSi droplets on Si(111) substrate subject to Si surface flux show that the supersaturation dependent surface tension destabilizes the contact line via formation of a precursor wetting film on the solid-vapor interface and has ramifications for size selection during droplet-catalyzed routes for nanowire growth. Our study sheds light on the interplay between stability and energetics of surfaces in this unique class of binary alloys and offers pathways for exploiting their surface structure for varied applications such as catalytic nanocrystal growth, dealloying, and polymer crystallization.

关键词： Crystal forms Growth Interface & surface thermodynamics Nanocrystals Structural phase transition 2-dimensional systems Surfaces Molecular dynamics

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The Power Control Method of Data Center Based on Cloud- Edge Collaboration

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Journal of Physics: Conference Series 2021年第1期1754卷

作者： Junjie Zhao Yucheng Hou Liu Liu Feng Xie Xiang Mao Pan Luo Jinxin Wang Zhiqiang Zhang Jiang Deng Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu 610213 China Key Laboratory of the Ministry of Education on Smart Power Grids (Tianjin University) Tianjin 300072 China

Data centers have the characteristics of huge energy consumption and strong power fluctuations. To solve the problem of unstable supply and demand such as frequent power fluctuations in the micro-grid of the data center using renewable energies, this paper establishes a controllable load model of server clusters based on the task migration mechanism by analyzing the various tasks and characteristics of large cloud data centers, as well as edge computing nodes. Through the collaborative optimization control of edge and cloud computing tasks, and dynamically adjusting and migrating the server cluster load, a new data center tie-line power control method is proposed. The results of calculation examples show that the method can achieve power smoothing of large-scale cloud data center tie lines through cloud-edge collaborative control.

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