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arXiv 2020年

作者： Shen, Tong Zhang, Xiao-Wei Shang, Honghui Zhang, Min-Ye Wang, Xinqiang Wang, En-Ge Jiang, Hong Li, Xin-Zheng State Key Laboratory for Artificial Microstructure and Mesoscopic Physics Frontier Science Center for Nano-optoelectronics School of Physics Peking University Beijing China International Center for Quantum Materials and School of Physics Peking University Beijing China State Key Laboratory of Computer Architecture Institute of Computing Technology Chinese Academy of Sciences Beijing China Beijing National Laboratory for Molecular Sciences College of Chemistry and Molecular Engineering Peking University Beijing China Collaborative Innovation Center of Quantum Matter Peking University Beijing100871 China Ceramic Division Songshan Lake Lab Institute of Physics Chinese Academy of Sciences Guangdong China School of Physics Liaoning University Shenyang China Beijing National Laboratory for Molecular Sciences College of Chemistry and Molecular Engineering Peking University Beijing China Collaborative Innovation Center of Quantum Matter Peking University Beijing China

We report ab initio band diagram and optical absorption spectra of hexagonal boron nitride (h-BN), focusing on unravelling how the completeness of basis set for GW calculations and how electron-phonon interactions (EPIs) impact on them. The completeness of basis set, an issue which was seldom discussed in previous optical spectra calculations of h-BN, is found crucial in providing converged quasiparticle band gaps. In the comparison among three different codes, we demonstrate that by including high-energy local orbitals in the all-electron linearized augmented plane waves based GW calculations, the quasiparticle direct and fundamental indirect band gaps are widened by ∼0.2 eV, giving values of 6.81 eV and 6.25 eV respectively at the GW0 level. EPIs, on the other hand, reduce them to 6.62 eV and 6.03 eV respectively at 0 K, and 6.60 eV and 5.98 eV respectively at 300 K. With clamped crystal structure, the first peak of the absorption spectrum is at 6.07 eV, originating from the direct exciton contributed by electron transitions around K in the Brillouin zone. After including the EPIs-renormalized quasiparticles in the Bethe-Salpeter equation, the exciton-phonon coupling shifts the first peak to 5.83 eV at 300 K, lower than the experimental value of ∼6.00 eV. This accuracy is acceptable to an ab initio description of excited states with no fitting parameter. Copyright © 2020, The Authors. All rights reserved.

关键词： III-V semiconductors

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Taking the pulse of COVID-19:a spatiotemporal perspective

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International Journal of Digital Earth 2020年第10期13卷 1186-1211页

作者： Chaowei Yang Dexuan Sha Qian Liu Yun Li Hai Lan Weihe Wendy Guan Tao Hu Zhenlong Li Zhiran Zhang John Hoot Thompson Zifu Wang David Wong Shiyang Ruan Manzhu Yu Douglas Richardson Luyao Zhang Ruizhi Hou You Zhoua Cheng Zhong Yifei Tian Fayez Beaini Kyla Carte Colin Flynn Wei Liu Dieter Pfoser Shuming Bao Mei Li Haoyuan Zhang Chunbo Liu Jie Jiang Shihong Du Liang Zhao Mingyue Lu Lin Li Huan Zhou Andrew Ding NSF Spatiotemporal Innovation Center George Mason Univ.FairfaxVAUSA Department of Geography and GeoInformation Science George Mason Univ.FairfaxVAUSA Department of Geographical Sciences University of MarylandCollege ParkMDUSA Center for Geographic Analysis Harvard UniversityCambridgeMAUSA Geoinformation and Big Data Research Lab Department of GeographyUniversity of South CarolinaColumbiaSCUSA Chinese Academy of Surveying and Mapping BeijingPeople’s Republic of China School of Resource and Environmental Sciences Wuhan UniversityWuhanPeople’s Republic of China Cloud Computeand Storage OperationsInformation Technology ServicesGeorge Mason UniversityFairfaxVAUSA Department of Geography Pennsylvania State UniversityState CollegePAUSA School of Business Management East China Normal UniversityShanghaiPeople’s Republic of China School of Mathematical Sciences East China Normal UniversityShanghaiPeople’s Republic of China Department of Psychology George Mason UniversityFairfaxVAUSA mDepartment of Computer Science George Mason UniversityFairfaxVAUSA Department of Information Technology George Mason UniversityFairfaxVAUSA Department of Biology George Mason UniversityFairfaxVAUSA College of Land Science and Technology China Agricultural UniversityBeijingPeople’s Republic of China China Data Institute Ann ArborMIUSA Institute of Remote Sensing and GIS Peking UniversityBeijingPeople’s Republic of China Aerospace Information Research Institute Chinese Academy of SciencesBeijingPeople’s Republic of China School of Geomatics and Urban Spatial Informatics Beijing University of Civil Engineering and ArchitectureBeijingPeople’s Republic of China School of Geographical Sciences Nanjing University of Information Science&TechnologyNanjingPeople’s Republic of China School of Geodesy and Geomatics Wuhan UniversityWuhanPeople’s Republic of China wFaculty of Environment University of WaterlooWaterlooCanada

The sudden outbreak of the Coronavirus disease(COVID-19)swept across the world in early 2020,triggering the lockdowns of several billion people across many countries,including China,Spain,India,the U.K.,Italy,France,Germany,Brazil,Russia,and the *** transmission of the virus accelerated rapidly with the most confirmed cases in the U.S.,India,Russia,and *** response to this national and global emergency,the NSF Spatiotemporal Innovation Center brought together a taskforce of international researchers and assembled implementation strategies to rapidly respond to this crisis,for supporting research,saving lives,and protecting the health of global *** perspective paper presents our collective view on the global health emergency and our effort in collecting,analyzing,and sharing relevant data on global policy and government responses,human mobility,environmental impact,socioeconomical impact;in developing research capabilities and mitigation measures with global scientists,promoting collaborative research on outbreak dynamics,and reflecting on the dynamic responses from human societies.

关键词： Big Data Earth system emergency geospatial sciences epidemics applications

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Deep learning based video system for accurate and real-time parking measurement

arXiv

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arXiv 2019年

作者： Cai, Bill Yang Alvarez, Ricardo Sit, Michelle Duarte, Fábio Ratti, Carlo Senseable City Lab Massachusetts Institute of Technology 77 Massachusetts Avenue CambridgeMA02139 United States Center for Computational Engineering Massachusetts Institute of Technology 77 Massachusetts Avenue CambridgeMA02139 United States School of Architecture and Design Pontifical Catholic University of Paraná R. Imac. ConceiÃgÃ čo 1155 - Prado Velho Curitiba - PR80215-901 Brazil Department of Computer Science and Engineering University of California San Diego 9500 Gilman Drive La JollaCA92093 United States

Parking spaces are costly to build, parking payments are difficult to enforce, and drivers waste an excessive amount of time searching for empty lots. Accurate quantification would inform developers and municipalities in space allocation and design, while real-time measurements would provide drivers and parking enforcement with information that saves time and resources. In this paper, we propose an accurate and real-time video system for future Internet of Things (IoT) and smart cities applications. Using recent developments in deep convolutional neural networks (DCNNs) and a novel vehicle tracking filter, we combine information across multiple image frames in a video sequence to remove noise introduced by occlusions and detection failures. We demonstrate that our system achieves higher accuracy than pure image-based instance segmentation, and is comparable in performance to industry benchmark systems that utilize more expensive sensors such as radar. Furthermore, our system shows significant potential in its scalability to a city-wide scale and also in the richness of its output that goes beyond traditional binary occupancy statistics. Copyright © 2019, The Authors. All rights reserved.

关键词： Internet of things

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Extended Linear Mixing Model in an Ecosytem with High Spectral Variability

Extended Linear Mixing Model in an Ecosytem with High Spectr...

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IEEE International Symposium on Geoscience and Remote Sensing (IGARSS)

作者： Edurne Ibarrola-Ulzurrun Lucas Drumetz Jocelyn Chanussot Consuelo Gonzalo-Martin Javier Marcello Department of Computer Architecture and Technology Universidad Politécnica de Madrid Boadilla del Monte Madrid Spain IMT Atlantique Lab-STICC Brest France CNRS GIPSA-Lab Grenoble France Universidad de Las Palmas de Gran Canaria Las Palmas de Gran Canaria Islas Canarias ES

Hyperspectral imagery (HSI) has become an important tool in ecosystem conservation due to its capability to perform accurate spectral unmixing, for vegetation mapping and ecosystem monitoring. An issue to be solved is the spectral variability of endmembers that can be induced by sensor noise and topographic changes. This spectral variability is considered by the Extended Linear Mixing Model (ELMM), which is applied to a mountainous ecosystem with high spectral variability and radiometric changes in each swath. The results obtained are very satisfactory, achieving reasonable abundance estimations and accurate characterization of the variability within the scene. ELMM allows studying the features of each pixel, including additional information about the characterization of the mixed pixels, in HSI by taking spectral variability into account. Moreover, it is observed that ELMM is robust to the absence of pure pixels as well as to noise.

关键词： Ecosystems Vegetation mapping Biological system modeling Hyperspectral imaging Radiometry Soil

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PHP: Power hungry pattern generation at higher abstraction level

PHP: Power hungry pattern generation at higher abstraction l...

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East-West Design & Test Symposium (EWDTS)

作者： Rohini Gulve Anshu Goel Virendra Singh Computer Architecture and Dependable Systems Lab Electrical Engineering Indian Institute of Technology Bombay India

The Performance, area, and power are most essential factors to be considered and optimize at every step in the design cycle. Design engineers often need to learn about these factors in order make right decisions on design strategies. Power analysis at lower levels of abstraction can provide more accurate analysis than higher levels. Worst case power can be estimated through high activity pattern generation. However, generation of such power hungry patterns (PHP) become challenging as the number of modules or design components increases. This process can be accelerated at higher abstraction levels by utilizing the available information. In this paper, we generate PHP by at higher abstraction level with significant speed up. A genetic algorithm is implemented to find out the global maximum power of designs. An experiment indicates that the process implemented is much faster and it finds about 10 % more power demanding PHP than random samples generated.

关键词： Mathematical model Genetic algorithms Integrated circuit modeling Logic gates Power demand Optimization Libraries

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Matrix architecture: 3d-printed and simulated kirigami matrices & auxetic materials 8

Matrix architecture: 3d-printed and simulated kirigami matri...

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8th Annual Symposium on Simulation for architecture and Urban Design, SimAUD 2017

作者： Eggers, Madeleine Liu, Jingyang Liu, Jasmine Chia-Chia Norman, Ben Sabin, Jenny E. Architecture Cornell University Ithaca United States Sabin Design Lab Cornell University Ithaca United States Material Science Cornell University Ithaca United States Computer Science Cornell University Ithaca United States

ISBN: (纸本)9781510870185

This paper explores the possibilities of kirigami geometry — folding with the addition of strategically placed cuts and holes — through simulation and kinetic and adaptive architectural assemblies. Typical kinetic assemblies consist of rigid components connected by mechanical joints that offer limited range of motion and tend to require mechatronic actuation. While mechanical motion is adequate for specific applications, mechanically motile systems lack the adaptive potential, elasticity, and embedded intelligence of adaptive structures. We propose to focus on the design of flexible matrices as a way of moving away from stiff, mechanical unitized systems and toward pliable, continuous 2D and 3D structures that can elastically change geometry in response to external stimuli without the need for external mechatronic energy input. As a proof-of-concept, we have produced an integrated panel-and-hinge assembly in which the panels and hinges are not discrete, mechanically connected components, but are instead functional zones of a continuous matrix. In addition, by controlling aspects of the individual units (panel size, hinge geometry, spacing, unit shape), we can induce larger-scale behavioral changes in the whole matrix. © 2017 Society for Modeling & Simulation International (SCS).

关键词： 3D printers

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EVALUATION OF HYPERSPECTRAL CLASSIFICATION MAPS IN HETEROGENEOUS ECOSYSTEM

EVALUATION OF HYPERSPECTRAL CLASSIFICATION MAPS IN HETEROGEN...

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IEEE International Geoscience and Remote Sensing Symposium

作者： Edurne Ibarrola-Ulzurrun Javier Marcello Consuelo Gonzalo-Martin Jocelyn Chanussot Department of Computer Architecture and Technology Universidad Politécnica de Madrid Madrid Spain Instituto de Oceanografía y Cambio Global IOCAG Universidad de Las Palmas de Gran Canaria ULPGC Telde Las Palmas Spain Univ. Grenoble Alpes GIPSA-lab Grenoble France

Ecosystem management and monitoring are essential to preserve natural resources. Hyperspectral imagery (HSI) is a useful tool to obtain accurate classification maps, providing significant level of detail. Thus, traditional and novel methodologies based on pixel and object classification approaches are compared and evaluated in a homogeneous and mixed vulnerable ecosystem. Considering the challenging ecosystem, all classifications successfully resulted in high OA (higher than 82%), showing that HSI is very useful providing accurate vegetation maps to evaluate and monitor the ecosystems in a faster and economic way.

关键词： Support vector machines Hyperspectral imaging Ecosystems Image segmentation Vegetation mapping

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Evolved control of natural plants: Crossing the reality gap for user-defined steering of growth and motion

Evolved control of natural plants: Crossing the reality gap ...

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作者： Hofstadler, Daniel Nicolas Wahby, Mostafa Heinrich, Mary Katherine Hamann, Heiko Zahadat, Payam Ayres, Phil Schmickl, Thomas Artificial Life Lab Department of Zoology University of Graz Universitatsplatz 2 GrazA-8010 Austria Paderborn University Germany Institute of Computer Engineering University of Lubeck Ratzeburger Allee 160 Lubeck23562 Germany Centre for IT and Architecture Royal Danish Academy of Fine Arts School of Architecture Philip de Langes Alle 10 Kobenhavn K1435 Denmark

Mixing societies of natural and artificial systems can provide interesting and potentially fruitful research targets. Here we mix robotic setups and natural plants in order to steer the motion behavior of plants while growing. The robotic setup uses a camera to observe the plant and uses a pair of light sources to trigger phototropic response, steering the plant to user-defined targets. An evolutionary robotic approach is used to design a controller for the setup. Initially, preliminary experiments are performed with a simple predetermined controller and a growing bean plant. The plant behavior in response to the simple controller is captured by image processing, and a model of the plant tip dynamics is developed. The model is used in simulation to evolve a robot controller that steers the plant tip such that it follows a number of randomly generated target points. Finally, we test the simulation-evolved controller in the real setup controlling a natural bean plant. The results demonstrate a successful crossing of the reality gap in the setup. The success of the approach allows for future extensions to more complex tasks including control of the shape of plants and pattern formation in multiple plant setups. 2017 Copyright is held by the owner/author(s). Publication rights licensed to ACM.

关键词： Controllers

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Author Correction: BigNeuron: a resource to benchmark and predict performance of algorithms for automated tracing of neurons in light microscopy datasets

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Nature methods 2024年第10期21卷 1959页

作者： Linus Manubens-Gil Zhi Zhou Hanbo Chen Arvind Ramanathan Xiaoxiao Liu Yufeng Liu Alessandro Bria Todd Gillette Zongcai Ruan Jian Yang Miroslav Radojević Ting Zhao Li Cheng Lei Qu Siqi Liu Kristofer E Bouchard Lin Gu Weidong Cai Shuiwang Ji Badrinath Roysam Ching-Wei Wang Hongchuan Yu Amos Sironi Daniel Maxim Iascone Jie Zhou Erhan Bas Eduardo Conde-Sousa Paulo Aguiar Xiang Li Yujie Li Sumit Nanda Yuan Wang Leila Muresan Pascal Fua Bing Ye Hai-Yan He Jochen F Staiger Manuel Peter Daniel N Cox Michel Simonneau Marcel Oberlaender Gregory Jefferis Kei Ito Paloma Gonzalez-Bellido Jinhyun Kim Edwin Rubel Hollis T Cline Hongkui Zeng Aljoscha Nern Ann-Shyn Chiang Jianhua Yao Jane Roskams Rick Livesey Janine Stevens Tianming Liu Chinh Dang Yike Guo Ning Zhong Georgia Tourassi Sean Hill Michael Hawrylycz Christof Koch Erik Meijering Giorgio A Ascoli Hanchuan Peng Institute for Brain and Intelligence Southeast University Nanjing China. Microsoft Corporation Redmond WA USA. Tencent AI Lab Bellevue WA USA. Computing Environment and Life Sciences Directorate Argonne National Laboratory Lemont IL USA. Kaya Medical Seattle WA USA. University of Cassino and Southern Lazio Cassino Italy. Center for Neural Informatics Structures and Plasticity Krasnow Institute for Advanced Study George Mason University Fairfax VA USA. Faculty of Information Technology Beijing University of Technology Beijing China. Beijing International Collaboration Base on Brain Informatics and Wisdom Services Beijing China. Nuctech Netherlands Rotterdam the Netherlands. Janelia Research Campus Howard Hughes Medical Institute Ashburn VA USA. Department of Electrical and Computer Engineering University of Alberta Edmonton Alberta Canada. Ministry of Education Key Laboratory of Intelligent Computation and Signal Processing Anhui University Hefei China. Paige AI New York NY USA. Scientific Data Division and Biological Systems and Engineering Division Lawrence Berkeley National Lab Berkeley CA USA. Helen Wills Neuroscience Institute and Redwood Center for Theoretical Neuroscience UC Berkeley Berkeley CA USA. RIKEN AIP Tokyo Japan. Research Center for Advanced Science and Technology (RCAST) The University of Tokyo Tokyo Japan. School of Computer Science University of Sydney Sydney New South Wales Australia. Texas A&M University College Station TX USA. Cullen College of Engineering University of Houston Houston TX USA. Graduate Institute of Biomedical Engineering National Taiwan University of Science and Technology Taipei Taiwan. National Centre for Computer Animation Bournemouth University Poole UK. PROPHESEE Paris France. Department of Neuroscience Columbia University New York NY USA. Mortimer B. Zuckerman Mind Brain Behavior Institute Columbia University New York NY USA. Department of Computer Science Northern Illinois Universit

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LEPR: Link Stability Estimation-based Preemptive Routing Protocol for Flying Ad Hoc Networks

LEPR: Link Stability Estimation-based Preemptive Routing Pro...

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IEEE Symposium on computers and Communications

作者： Xianfeng Li Jiaojiao Yan Shenzhen Key Lab of Information Theory & Future Network Architecture School of Electronic and Computer Engineering Peking University Shenzhen China

Flying Ad Hoc Network (FANET) consisting of Unmanned Aerial Vehicles (UAVs) can undertake many tasks difficult for traditional Mobile Ad Hoc Networks (MANETs). However, the highly dynamic topology of FANET imposes difficulties for adopting existing MANET routing protocols. In this paper, we present the Link Stability Estimation-based Preemptive Routing (LEPR) protocol targeting FANET on the basis of AODV, an existing routing protocol for ad hoc networks. Taking advantage of GPS location information of UAVs, a new link stability metric is introduced for LEPR. This new metric uses the link quality, safety degree and mobility prediction factor to take into account the past, current and future statuses of link stability respectively. With this new metric, LEPR calculates multiple robust link-disjoint paths during the route discovery process. In addition, a semi-proactive route maintenance process is initiated when anticipating link breaks. This preemptive mechanism reduces the number of broken paths and packet latency by finding and switching to a more reliable path early. Simulation results demonstrate that LEPR significantly outperforms two popular routing protocols, AODV and DSR, in terms of packet delivery ratio, delay and routing overhead, whether in a high or low mobility setting.

关键词： Measurement Routing protocols Routing Ad hoc networks Stability analysis Safety

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