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arXiv 2024年

作者： Gui, Ke Zhang, Xutao Che, Huizheng Li, Lei Zheng, Yu An, Linchang Miao, Yucong Zhao, Hujia Dubovik, Oleg Holben, Brent Wang, Jun Gupta, Pawan Lind, Elena S. Toledano, Carlos Wang, Hong Wang, Zhili Wang, Yaqiang Huang, Xiaomeng Dai, Kan Xia, Xiangao Xu, Xiaofeng Zhang, Xiaoye State Key Laboratory of Severe Weather Key Laboratory of Atmospheric Chemistry of CMA Chinese Academy of Meteorological Sciences Beijing China National Meteorological Center CMA Beijing China Institute of Atmospheric Environment China Meteorological Administration Shenyang China Université de Lille CNRS UMR 8518–Laboratoire d’Optique Atmosphérique Lille France NASA Goddard Space Flight Center GreenbeltMD United States Department of Chemical and Biochemical Engineering The University of Iowa Iowa CityIA United States HuntsvilleAL United States NASA Marshall Space Flight Center HuntsvilleAL United States Department of Electrical and Computer Engineering Virginia Tech BlacksburgVA United States Grupo de Optica Atmosférica Universidad de Valladolid Paseo Prado de la Magdalena Valladolid Spain Institute of Artificial Intelligence for Meteorological Chinese Academy of Meteorological Sciences Beijing China Department of Earth System Science Tsinghua University Beijing China Key Laboratory of Middle Atmosphere and Global Environment Observation Institute of Atmospheric Physics Chinese Academy of Sciences Beijing China China Meteorological Administration Beijing China

Aerosol forecasting is essential for air quality warnings, health risk assessment, and climate change mitigation. However, it is more complex than weather forecasting due to the intricate interactions between aerosol physicochemical processes and atmospheric dynamics, resulting in significant uncertainty and high computational costs. Here, we develop an artificial intelligence-driven global aerosol-meteorology forecasting system (AI-GAMFS), which provides reliable 5-day, 3-hourly forecasts of aerosol optical components and surface concentrations at a 0.5° × 0.625° resolution. AI-GAMFS combines Vision Transformer and U-Net in a backbone network, robustly capturing the complex aerosol-meteorology interactions via global attention and spatiotemporal encoding. Trained on 42 years of advanced aerosol reanalysis data and initialized with GEOS Forward Processing (GEOS-FP) analyses, AI-GAMFS delivers operational 5-day forecasts in one minute. It outperforms the Copernicus Atmosphere Monitoring Service (CAMS) global forecasting system, GEOS-FP forecasts, and several regional dust forecasting systems in forecasting most aerosol variables including aerosol optical depth and dust components. Our results mark a significant step forward in leveraging AI to refine physics-based aerosol forecasting, facilitating more accurate global warnings for aerosol pollution events, such as dust storms and wildfires. Copyright © 2024, The Authors. All rights reserved.

关键词： Risk assessment

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Observation of the dual quantum spin Hall insulator by density-tuned correlations in a van der Waals monolayer

arXiv

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arXiv 2024年

作者： Tang, Jian Ding, Thomas Siyuan Chen, Hongyu Gao, Anyuan Qian, Tiema Huang, Zumeng Sun, Zhe Han, Xin Strasser, Alex Li, Jiangxu Geiwitz, Michael Shehabeldin, Mohamed Belosevich, Vsevolod Wang, Zihan Wang, Yiping Watanabe, Kenji Taniguchi, Takashi Bell, David C. Wang, Ziqiang Fu, Liang Zhang, Yang Qian, Xiaofeng Burch, Kenneth S. Shi, Youguo Ni, Ni Chang, Guoqing Xu, Su-Yang Ma, Qiong Department of Physics Boston College Chestnut HillMA United States Division of Physics and Applied Physics School of Physical and Mathematical Sciences Nanyang Technological University Singapore Singapore Department of Chemistry and Chemical Biology Harvard University CambridgeMA United States Department of Physics and Astronomy and California NanoSystems Institute University of California Los Angeles Los AngelesCA United States Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences Beijing China Department of Materials Science and Engineering Texas A&M University College StationTX United States Department of Physics and Astronomy University of Tennessee KnoxvilleTN United States Min H. Kao Department of Electrical Engineering and Computer Science University of Tennessee KnoxvilleTN United States Research Center for Electronic and Optical Materials National Institute for Materials Science Tsukuba Japan Research Center for Materials Nanoarchitectonics National Institute for Materials Science Tsukuba Japan Harvard John A. Paulson School of Engineering and Applied Sciences The Center for Nanoscale system Harvard University CambridgeMA United States Department of Physics Massachusetts Institute of Technology CambridgeMA United States CIFAR Azrieli Global Scholars program CIFAR Toronto Canada

The convergence of topology and correlations represents a highly coveted realm in the pursuit of novel quantum states of matter [1, 2]. Introducing electron correlations to a quantum spin Hall (QSH) insulator can lead to the emergence of a fractional topological insulator and other exotic time-reversal-symmetric topological order [3- 10], not possible in quantum Hall and Chern insulator systems. However, the QSH insulator with quantized edge conductance remains rare, let alone that with significant correlations. In this work, we report a novel dual QSH insulator within the intrinsic monolayer crystal of TaIrTe4, arising from the interplay of its single-particle topology and density-tuned electron correlations. At charge neutrality, monolayer TaIrTe4 demonstrates the QSH insulator that aligns with single-particle band structure calculations, manifesting enhanced nonlocal transport and quantized helical edge conductance. Interestingly, upon introducing electrons from charge neutrality, TaIrTe4 only shows metallic behavior in a small range of charge densities but quickly goes into a new insulating state, entirely unexpected based on TaIrTe4's single-particle band structure. This insulating state could arise from a strong electronic instability near the van Hove singularities (VHS), likely leading to a charge density wave (CDW). Remarkably, within this correlated insulating gap, we observe a resurgence of the QSH state, marked by the revival of nonlocal transport and quantized helical edge conduction. Our observation of helical edge conduction in a CDW gap could bridge spin physics and charge orders. The discovery of a dual QSH insulator introduces a new method for creating topological flat minibands via CDW superlattices, which offer a promising platform for exploring time-reversal-symmetric fractional phases and electromagnetism [3-5, 11, 12]. Copyright © 2024, The Authors. All rights reserved.

关键词： Charge density waves

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Observation of intrinsic chiral bound states in the continuum

arXiv

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arXiv 2022年

作者： Chen, Yang Deng, Huachun Sha, Xinbo Chen, Weijin Wang, Ruize Chen, Yuhang Wu, Dong Chu, Jiaru Kivshar, Yuri S. Xiao, Shumin Qiu, Cheng-Wei Department of Electrical and Computer Engineering National University of Singapore Singapore117583 Singapore Chinese Academy of Sciences Key Laboratory of Mechanical Behavior and Design of Materials Department of Precision Machinery and Precision Instrumentation University of Science and Technology of China Hefei230027 China Ministry of Industry and Information Technology Key Lab of Micro-Nano Optoelectronic Information System Harbin Institute of Technology Shenzhen518055 China Nonlinear Physics Center Research School of Physics Australian National University CanberraACT2601 Australia Pengcheng Laboratory Shenzhen518055 China

Photons with spin angular momentum possess intrinsic chirality which underpins many phenomena including nonlinear optics1, quantum optics2, topological photonics3 and chiroptics4. Intrinsic chirality is weak in natural materials, and recent theoretical proposals5-7 aimed to enlarge circular dichroism by resonant metasurfaces supporting bound states in the continuum that enhance substantially chiral light-matter interaction. Those insightful works resort to three-dimensional sophisticated geometries, which are too challenging to be realized for optical frequencies8. Therefore, most of the experimental attempts9-11 showing strong circular dichroism rely on false/extrinsic chirality by employing either oblique incidence9, 10 or structural anisotropy11. Here, we report on the experimental realization of true/intrinsic chiral response with resonant metasurfaces where the engineered slant geometry breaks both in-plane and out-of-plane symmetries. Our result marks the first observation of intrinsic chiral bound states in the continuum with near-unity chiral dichroism of 0.93 and record-high quality factor exceeding 2663 for visible frequencies. Our chiral metasurfaces promise a plethora of applications in chiral light sources and detectors, chiral sensing, valleytronics and asymmetric photocatalysis. © 2022, CC BY.

关键词： Dichroism

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Deep Reinforcement Learning Based Intelligent Reflecting Surface for Secure Wireless Communications

arXiv

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arXiv 2020年

作者： Yang, Helin Xiong, Zehui Zhao, Jun Niyato, Dusit Xiao, Liang Wu, Qingqing School of Computer Science and Engineering Nanyang Technological University Singapore639798 Singapore Department of Information and Communication Engineering Key Laboratory of Digital Fujian on IoT Communication Architecture and Security Technology Xiamen University Xiamen361005 China Department of Electrical and Computer Engineering National University of Singapore Singapore119260 Singapore

In this paper, we study an intelligent reflecting surface (IRS)-aided wireless secure communication system for physical layer security, where an IRS is deployed to adjust its reflecting elements to secure the communication of multiple legitimate users in the presence of multiple eavesdroppers. Aiming to improve the system secrecy rate, a design problem for jointly optimizing the base station (BS)’s beamforming and the IRS’s reflecting beamforming is formulated considering different quality of service (QoS) requirements and time-varying channel conditions. As the system is highly dynamic and complex, and it is challenging to address the non-convex optimization problem, a novel deep reinforcement learning (DRL)-based secure beamforming approach is firstly proposed to achieve the optimal beamforming policy against eavesdroppers in dynamic environments. Furthermore, post-decision state (PDS) and prioritized experience replay (PER) schemes are utilized to enhance the learning efficiency and secrecy performance. Specifically, PDS is capable of tracing the environment dynamic characteristics and adjust the beamforming policy accordingly. Simulation results demonstrate that the proposed deep PDS-PER learning based secure beamforming approach can significantly improve the system secrecy rate and QoS satisfaction probability in IRS-aided secure communication systems. Copyright © 2020, The Authors. All rights reserved.

关键词： Deep learning

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Video-based point cloud compression artifact removal

arXiv

引用

arXiv 2021年

作者： Akhtar, Anique Gao, Wen Li, Li Li, Zhu Jia, Wei Liu, Shan Department of Computer Science and Electrical Engineering University of Missouri-Kansas City Kansas CityMO64110 United States Tencent America 661 Bryant St. Palo AltoCA94301 United States Department of Computer Science and Electrical Engineering University of Missouri-Kansas City Kansas CityMO64110 United States CAS Key Laboratory of Technology in Geo-Spatial Information Processing and Application System University of Science and Technology of China Hefei230027 China

—Photo-realistic point cloud capture and transmission are the fundamental enablers for immersive visual communication. The coding process of dynamic point clouds, especially video-based point cloud compression (V-PCC) developed by the MPEG standardization group, is now delivering state-of-the-art performance in compression efficiency. V-PCC is based on the projection of the point cloud patches to 2D planes and encoding the sequence as 2D texture and geometry patch sequences. However, the resulting quantization errors from coding can introduce compression artifacts, which can be very unpleasant for the quality of experience (QoE). In this work, we developed a novel out-of-the-loop point cloud geometry artifact removal solution that can significantly improve reconstruction quality without additional bandwidth cost. Our novel framework consists of a point cloud sampling scheme, an artifact removal network, and an aggregation scheme. The point cloud sampling scheme employs a cube-based neighborhood patch extraction to divide the point cloud into patches. The geometry artifact removal network then processes these patches to obtain artifact-removed patches. The artifact-removed patches are then merged together using an aggregation scheme to obtain the final artifact-removed point cloud. We employ 3D deep convolutional feature learning for geometry artifact removal that jointly recovers both the quantization direction and the quantization noise level by exploiting projection and quantization prior. The simulation results demonstrate that the proposed method is highly effective and can considerably improve the quality of the reconstructed point cloud. Copyright © 2021, The Authors. All rights reserved.

关键词： Geometry

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A detailed comparison of MYD11 and MYD21 land surface temperature products in China's Mainland

引用

International Journal of digital Earth 2020年第12期13卷 1391-1407页

作者： Rui Yao Lunche Wang Shaoqiang Wang Lizhe Wang Jing Wei Junli Li Deqing Yu Hunan Key Laboratory of Remote Sensing of Ecological Environment in Dongting Lake Area School of Geography and Information EngineeringChina University of GeosciencesWuhanPeople’s Republic of China Hubei Key Laboratory of Critical Zone Evolution School of Geography and Information EngineeringChina University of GeosciencesWuhanPeople’s Republic of China Faculty of Computer Science China University of GeosciencesWuhanPeople’s Republic of China Hubei Key Laboratory of Intelligent Geo-Information Processing China University of GeosciencesWuhanPeople’s Republic of China State Key Laboratory of Remote Sensing Science College of Global Change and Earth System ScienceBeijing Normal UniversityBeijingPeople’s Republic of China Department of Atmospheric and Oceanic Science Earth System Science Interdisciplinary CenterUniversity of MarylandCollege ParkMDUSA School of Resources and Environment Anhui Agricultural UniversityHefeiAnhuiPeople’s Republic of China Hunan Key Laboratory of remote sensing of ecological environment in Dongting Lake Area Hunan Natural Resources Affairs CenterChangshaPeople’s Republic of China

Land surface temperature(LST)is a key parameter in land surface *** National Aeronautics and Space Administration(NASA)recently released new Moderate Resolution Imaging Spectroradiometer(MODIS)LST products(MOD21 and MYD21).Here,we conducted a detailed comparison between the MYD11 and MYD21 LST data in China's *** LSTs of MYD21 were approximately 1℃ higher than those of MYD11 averaged for China's Mainland,as MYD21 corrected the cold bias of *** proportions of the valid value of MYD21 were generally lower than those of MYD11 because the cloud removal method of MYD21 was stricter than that of ***,the outliers were less significant in MYD11 than in MYD21 because the outliers in MYD11 were removed using temporal constraints on *** outliers in MYD21A2 resulted in a difference of greater than 3℃ in average seasonal surface urban heat island intensity(SUHII)between MYD11A2 and ***,using MYD11 may underestimate the slope of long-term trends of ***21 LST data may have some uncertainties in urban *** study provided a reference for users for selecting LST products and for data producers to further improve MODIS LST products.

关键词： Remote sensing land surface temperature data comparison surface urban heat island China's Mainland

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Hardware Acceleration of Kalman Filter for Leak Detection in Water Pipeline systems using Wireless Sensor Network

Hardware Acceleration of Kalman Filter for Leak Detection in...

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2019 International Conference on High Performance Computing and Simulation, HPCS 2019

作者： Karray, Fatma Maalaoui, Melek Obeid, Abdulfattah M. Garcia-Ortiz, Alberto Abid, Mohamed National Engineering School of Sfax Computer and Embedded System Laboratory Sfax Tunisia Digital Research Center of Sfax Sfax Tunisia National Center for Electronics and Photonics Technology Riyadh Saudi Arabia Bremen Germany

ISBN: (纸本)9781728144849

The world migration towards automatic and wire-less systems results an increased usage of Wireless Sensor Networks (WSNs). The noticeable popularity of WSNs has imposed enlarged computational in-node demands. Hence, the recourse to fully-integrated and sophisticated systems with low power is a challenging task. Since wireless sensor nodes have limited power resources, it is important to find a balance between energy consumption and computational performance. The traditional software optimizations are not usually suited or enough to find this tradeoff. Consequently, the use of codesign methodology and the careful implementation of hardware accelerator with low frequency processors could offer a good compromise between energy consumption and performance. In this paper, we present a SoC WSN node prototype based on Leon 3 processor for leak detection in water pipeline using Kalman Filter (KF). A hardware acceleration of the KF has been designed and implemented to reduce energy consumption. We have compared also the software implementation of the algorithm and its hardware acceleration in terms of the execution time, the energy consumption and the area requirements. The results show about 97% reduction in energy consumption and execution time without noticeable increased area. © 2019 IEEE.

关键词： system-on-chip

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An Efficient Evolutionary Algorithm for High-Speed Train Rescheduling Under a Partial Station Blockage

SSRN

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SSRN 2023年

作者： Wang, Rongsheng Zhang, Qi Dai, Xuewu Yuan, Zhiming Zhang, Tao Ding, Shuxin Jin, Yaochu China Academy of Railway Sciences Corporation Limited Beijing100081 China Signal and Communication Research Institute China Academy of Railway Sciences Corporation Limited Beijing100081 China Train Operation Control Laboratory for High-Speed Railway National Engineering Research Center of System Technology for High-Speed Railway and Urban Rail Transit Beijing100081 China State Key Laboratory of Synthetical Automation for Process Industries Northeastern University Shenyang110819 China Faculty of Technology Bielefeld University BielefeldD-33615 Germany Department of Computer Science University of Surrey GuildfordGU2 7XH United Kingdom

This paper investigates the high-speed train rescheduling (HSTR) problem under a partial station blockage and proposes an efficient problem-specific strengthen elitist genetic algorithm (PS-SEGA) for HSTR. An HSTR model that is subject to train operation constraints is established to minimize the total train delay. The PS-SEGA framework consists of the following main steps. Firstly, a permutation-based encoding method is developed to define an efficient search space based on a train departure sequence. A decoding method is employed to output the rescheduled timetable and objective value based on the departure sequence. Moreover, a hybrid initialization method involving an efficient heuristic strategy (EHS) is put forward to accelerate the convergence speed of Evolutionary algorithms (EAs). Using problem-specific knowledge, EHS generates an efficient and feasible solution for the initial population. Finally, a restart strategy is presented to maintain genetic diversity. Compared with other advanced EAs and their improved variants also using the PS-SEGA framework, experimental results demonstrate the effectiveness of the proposed PS-SEGA for addressing HSTR scenarios under the partial station blockage. As for the scenarios that CPLEX can not obtain optimal solutions within 10 minutes, PS-SEGA can all provide quasi-optimal solutions in real-time. Furthermore, compared with the other two strategies (i.e., First-Scheduled-First-Served and EHS), PS-SEGA can find the best departure sequence that can output the timetable with a quasi-optimal solution. © 2023, The Authors. All rights reserved.

关键词： Genetic algorithms

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Iterative rational krylov algorithms for model reduction of a class of constrained structural dynamic system with engineering applications

arXiv

引用

arXiv 2021年

作者： Du, Xin Uddin, Mohammad Monir Fony, A. Mostakim Hossain, Md. Tanzim Shuzan, Md. Nazmul Islam School of Mechatronic Engineering and Automation Shanghai University Shanghai200072 China Key Laboratory of Modern Power System Simulation and Control & Renewable Energy Technology Ministry of Education Northeast Electric Power University Jilin132012 China Department of Mathematics and Physics North south University Dhaka1229 Bangladesh Department of Mathematics Chittagong University Chittagong Bangladesh Department of Electrical and Computer Engineering North South University Dhaka1229 Bangladesh

This paper discusses model order reduction of large sparse second-order index-3 differential algebraic equations (DAEs) by applying Iterative Rational Krylov Algorithm (IRKA). In general, such DAEs arise in constraint mechanics, multibody dynamics, mechatronics and many other branches of sciences and technologies. By deflecting the algebraic equations the second-order index-3 system can be altered into an equivalent standard second-order system. This can be done by projecting the system onto the null space of the constraint matrix. However, creating the projector is computationally expensive and it yields huge bottleneck during the implementation. This paper shows how to find a reduce order model without projecting the system onto the null space of the constraint matrix explicitly. To show the efficiency of the theoretical works we apply them to several data of second-order index-3 models and experimental resultants are discussed in the paper. © 2021, CC BY.

关键词： Differential equations

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Uav trajectory and communication co-design: flexible path discretization and path compression

arXiv

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arXiv 2020年

作者： Guo, Yijun You, Changsheng Yin, Changchuan Zhang, Rui Beijing Key Laboratory of Network System Architecture and Convergence Beijing University of Posts and Telecommunications China Department of Electrical and Computer Engineering National University of Singapore Singapore

The performance optimization of UAV communication systems requires the joint design of UAV trajectory and communication efficiently. To tackle the challenge of infinite design variables arising from the continuous-time UAV trajectory optimization, a commonly adopted approach in the existing literature is by approximating the UAV trajectory with piecewise-linear path segments connected via a finite number of waypoints in three-dimensional (3D) space. However, this approach may still incur prohibitive computational complexity in practice when the UAV flight period/distance becomes long, as the distance between consecutive waypoints needs to be kept sufficiently small to retain high approximation accuracy. To resolve this fundamental issue, we propose in this paper a new and general framework for UAV trajectory and communication co-design with flexible number of waypoint optimization variables (called designable waypoints) or their sub-path representations. First, we propose a flexible path discretization scheme that optimizes only a number of selected waypoints (designable waypoints) along the UAV path for complexity reduction, while all the designable and non-designable waypoints are used in calculating the approximated communication utility along the UAV trajectory for ensuring high trajectory discretization accuracy. Next, given any number of designable waypoints, we propose a novel path compression scheme where the UAV 3D path is first decomposed into three one-dimensional (1D) sub-paths and each sub-path is then approximated by superimposing a number of selected basis paths (which are generally less than the number of designable waypoints) weighted by their corresponding path coefficients, thus further reducing the path design complexity. Finally, we provide a case study on UAV trajectory design for aerial data harvesting from distributed ground sensors, and numerically show that the proposed flexible path discretization and path compression schemes can significa

关键词： Unmanned aerial vehicles (UAV)

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