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arXiv 2020年

作者： McGruder, Chima D. López-Morales, Mercedes Espinoza, Néstor Rackham, Benjamin V. Apai, Dániel Jordán, Andrés Osip, David J. Alam, Munazza K. Bixel, Alex Fortney, Jonathan J. Henry, Gregory W. Kirk, James Lewis, Nikole K. Rodler, Florian Weaver, Ian C. Center for Astrophysics Harvard & Smithsonian 60 Garden St CambridgeMA02138 United States 3700 San Martin Dr BaltimoreMD21218 United States Department of Earth Atmospheric and Planetary Sciences Kavli Institute for Astrophysics and Space Research Massachusetts Institute of Technology CambridgeMA02139 United States Department of Astronomy/Steward Observatory University of Arizona 933 N. Cherry Avenue TucsonAZ85721 United States Lunar and Planetary Laboratory University of Arizona 1640 E. Univ. Blvd TucsonAZ85721 United States Earths in Other Solar Systems Team NASA Nexus for Exoplanet System Science Facultad de Ingeniería y Ciencias Universidad Adolfo Ibáñez Av. Diagonal las Torres 2640 Peñalolén Santiago Chile Millennium Institute for Astrophysics Santiago Chile Las Campanas Observatory Carnegie Institution of Washington Colina el Pino Casilla 601 La Serena Chile Department of Astronomy and Astrophysics University of California Santa Cruz United States Center of Excellence in Information Systems Tennessee State University NashvilleTN37209 United States Department of Astronomy and Carl Sagan Institute Cornell University 122 Sciences Drive 14853 IthacaNY United States European Southern Observatory Alonso de Cordova 3107 Vitacura Santiago de Chile Chile

We present a new optical (400–950 nm) transmission spectrum of the hot Jupiter WASP-31b (M=0.48 MJ;R= 1.54 RJ;P=3.41 days), obtained by combining four transits observations. These transits were observed with IMACS on the Magellan Baade Telescope at Las Campanas Observatory as part of the ACCESS project. We investigate the presence of clouds/hazes in the upper atmosphere of this planet as well as the contribution of stellar activity on the observed features. In addition, we search for absorption features of the alkali elements Na I and K I, with particular focus on K I, for which there have been two previously published disagreeing results. Observations with HST/STIS detected K I, whereas ground-based low- and high-resolution observations did not. We use equilibrium and non-equilibrium chemistry retrievals to explore the planetary and stellar parameter space of the system with our optical data combined with existing near-IR observations. Our best-fit model is that with a scattering slope consistent with a Rayleigh slope (α = 5.3+2.9−3.1), high-altitude clouds at a log cloud top pressure of -3.6−2.1+2.7 bars, and possible muted H2O features. We find that our observations support other ground-based claims of no K I. Clouds are likely why signals like H2O are extremely muted and Na or K cannot be detected. We then juxtapose our Magellan/IMACS transmission spectrum with existing VLT/FORS2, HST/WFC3, HST/STIS, and Spitzer observations to further constrain the optical-to-infrared atmospheric features of the planet. We find that a steeper scattering slope (α = 8.3 ± 1.5) is anchored by STIS wavelengths blueward of 400 nm and only the original STIS observations show significant potassium signal. Copyright © 2020, The Authors. All rights reserved.

关键词： Planets

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Comparison of computational codes for direct numerical simulations of turbulent Rayleigh-Bénard convection

arXiv

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arXiv 2018年

作者： Kooij, Gijs L. Botchev, Mikhail A. Frederix, Edo M.A. Geurts, Bernard J. Horn, Susanne Lohse, Detlef Van Der Poel, Erwin P. Shishkina, Olga Stevens, Richard J.A.M. Verzicco, Roberto Multiscale Modeling and Simulation Faculty EEMCS University of Twente Enschede Netherlands Applied Mathematics and Mathematical Physics Imperial College London Physics of Fluids Faculty of Science and Technology University of Twente Enschede Netherlands Mathematics of Computational Science Faculty EEMCS University of Twente Enschede Netherlands Keldysh Institute of Applied Mathematics Russian Academy of Sciences Moscow Russia Max Planck Institute for Dynamics and Self-Organization Göttingen Germany Dipartimento di Ingegneria Meccanica Università di Roma Tor Vergata Rome Italy Faculty of Applied Physics Fluid Dynamics Laboratory Eindhoven University of Technology Eindhoven Netherlands Earth Planetary and Space Sciences University of California Los Angeles United States

Computational codes for direct numerical simulations of Rayleigh-Bénard (RB) convection are compared in terms of computational cost and quality of the solution. As a benchmark case, RB convection at Ra = 108and Pr = 1 in a periodic domain, in cubic and cylindrical containers is considered. A dedicated second-order finite-difference code (AFID/RBflow) and a specialized fourth-order finite-volume code (Goldfish) are compared with a general purpose finite-volume approach (OpenFOAM) and a general purpose spectral-element code (Nek5000). Reassuringly, all codes provide predictions of the average heat transfer that converge to the same values. The computational costs, however, are found to differ considerably. The specialized codes AFID/RBflow and Goldfish are found to excel in efficiency, outperforming the general purpose flow solvers Nek5000 and OpenFOAM by an order of magnitude with an error on the Nusselt number Nu below 5%. However, we find that Nu alone is not sufficient to assess the quality of the numerical results: in fact, instantaneous snapshots of the temperature field from a near wall region obtained for deliberately under-resolved simulations using Nek5000 clearly indicate inadequate flow resolution even when Nu is converged. Overall, dedicated special purpose codes for RB convection are found to be more efficient than general purpose codes. Copyright © 2018, The Authors. All rights reserved.

关键词： Direct numerical simulation

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Overview of KAGRA: KAGRA science

arXiv

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arXiv 2020年

作者： Akutsu, T. Ando, M. Arai, K. Arai, Y. Araki, S. Araya, A. Aritomi, N. Asada, H. Aso, Y. Bae, S. Bae, Y. Baiotti, L. Bajpai, R. Barton, M.A. Cannon, K. Cao, Z. Capocasa, E. Chan, M. Chen, C. Chen, K. Chen, Y. Chiang, C.-Y. Chu, H. Chu, Y.-K. Eguchi, S. Enomoto, Y. Flaminio, R. Fujii, Y. Fujikawa, F. Fukunaga, M. Fukushima, M. Gao, D. Ge, G. Ha, S. Hagiwara, A. Haino, S. Han, W.-B. Hasegawa, K. Hattori, K. Hayakawa, H. Hayama, K. Himemoto, Y. Hiranuma, Y. Hirata, N. Hirose, E. Hong, Z. Hsieh, B.H. Huang, C.-Z. Huang, H.-Y. Huang, P. Huang, Y.-C. Huang, Y. Hui, D.C.Y. Ide, S. Ikenoue, B. Imam, S. Inayoshi, K. Inoue, Y. Ioka, K. Ito, K. Itoh, Y. Izumi, K. Jeon, C. Jin, H.-B. Jung, K. Jung, P. Kaihotsu, K. Kajita, T. Kakizaki, M. Kamiizumi, M. Kanda, N. Kang, G. Kashiyama, K. Kawaguchi, K. Kawai, N. Kawasaki, T. Kim, C. Kim, J. Kim, J.C. Kim, W.S. Kim, Y.-M. Kimura, N. Kita, N. Kitazawa, H. Kojima, Y. Kokeyama, K. Komori, K. Kong, A.K.H. Kotake, K. Kozakai, C. Kozu, R. Kumar, R. Kume, J. Kuo, C. Kuo, H.-S. Kuromiya, Y. Kuroyanagi, S. Kusayanagi, K. Kwak, K. Lee, H.K. Lee, H.W. Lee, R. Leonardi, M. Li, T.G.F. Li, K.L. Lin, L.C.-C. Lin, C.-Y. Lin, F.-K. Lin, F.-L. Lin, H.L. Liu, G.C. Luo, L.-W. Majorana, E. Marchio, M. Michimura, Y. Mio, N. Miyakawa, O. Miyamoto, A. Miyazaki, Y. Miyo, K. Miyoki, S. Mori, Y. Morisaki, S. Moriwaki, Y. Nagano, K. Nagano, S. Nakamura, K. Nakano, H. Nakano, M. Nakashima, R. Nakayama, Y. Narikawa, T. Naticchioni, L. Negishi, R. Nguyen Quynh, L. Ni, W.-T. Nishizawa, Atsushi Nozaki, S. Obuchi, Y. Ogaki, W. Oh, J.J. Oh, K. Oh, S.H. Ohashi, M. Ohishi, N. Ohkawa, M. Ohta, H. Okutani, Y. Okutomi, K. Oohara, K. Ooi, C.P. Oshino, S. Otabe, S. Pan, K. Pang, H. Parisi, A. Park, J. Peña Arellano, F.E. Pinto, I. Sago, N. Saito, S. Saito, Y. Sakai, K. Sakai, Y. Sakuno, Y. Sato, S. Sato, T. Sawada, T. Mitaka City Tokyo181-8588 Japan Mitaka City Tokyo181-8588 Japan Department of Physics University of Tokyo Bunkyo-ku Tokyo113-0033 Japan University of Tokyo Bunkyo-ku Tokyo113-0033 Japan KAGRA Observatory University of Tokyo Kashiwa City Chiba277-8582 Japan Tsukuba City Ibaraki305-0801 Japan Earthquake Research Institute University of Tokyo Bunkyo-ku Tokyo113-0032 Japan Department of Mathematics and Physics Hirosaki University Hirosaki City Aomori036-8561 Japan Kamioka-cho Hida City Gifu506-1205 Japan Mitaka City Tokyo181-8588 Japan Yuseong-gu Daejeon34141 Korea Republic of National Institute for Mathematical Sciences Daejeon34047 Korea Republic of International College Osaka University Toyonaka City Osaka560-0043 Japan Tsukuba City Ibaraki305-0801 Japan Department of Astronomy Beijing Normal University Beijing100875 China Department of Applied Physics Fukuoka University Jonan Fukuoka City Fukuoka814-0180 Japan Department of Physics Tamkang University Danshui Dist. New Taipei City25137 Taiwan Department of Physics and Institute of Astronomy National Tsing Hua University Hsinchu30013 Taiwan Department of Physics Center for High Energy and High Field Physics National Central University Zhongli District Taoyuan City32001 Taiwan Institute of Physics Academia Sinica Nankang Taipei11529 Taiwan Université Savoie Mont Blanc CNRS/IN2P3 AnnecyF-74941 France Department of Astronomy University of Tokyo Mitaka City Tokyo181-8588 Japan Faculty of Engineering Niigata University Nishi-ku Niigata City Niigata950-2181 Japan State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics China Chinese Academy of Sciences Xiao Hong Shan Wuhan430071 China Ulsan44919 Korea Republic of Tsukuba City Ibaraki305-0801 Japan Chinese Academy of Sciences Shanghai Astronomical Observatory Shanghai200030 China Faculty of Science University of Toyama Toyama City Toyama930-8555 Japan KAGRA

KAGRA is a newly build GW observatory, a laser interferometer with 3 km arm length, located in Kamioka, Gifu, Japan. In this paper in the series of KAGRA-featured articles, we discuss the science targets of KAGRA projects, considering not only the baseline KAGRA (current design) but also its future upgrade candidates (KAGRA+) for the near to middle term (∼5 years). Copyright © 2020, The Authors. All rights reserved.

关键词： Interferometers

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ASASSN-14ko is a periodic nuclear transient in ESO 253−G003

arXiv

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arXiv 2020年

作者： Payne, Anna V. Shappee, Benjamin J. Hinkle, Jason T. Vallely, Patrick J. Kochanek, Christopher S. Holoien, Thomas W.-S. Auchettl, Katie Stanek, K.Z. Thompson, Todd A. Neustadt, Jack M.M. Tucker, Michael A. Armstrong, James D. Brimacombe, Joseph Cacella, Paulo Cornect, Robert Denneau, Larry Fausnaugh, Michael M. Flewelling, Heather Grupe, Dirk Heinze, A.N. Lopez, Laura A. Monard, Berto Prieto, Jose L. Schneider, Adam C. Sheppard, Scott S. Tonry, John L. Weiland, Henry Institute for Astronomy University of Hawai'i at Manoa 2680 Woodlawn Dr. HonoluluHI96822 United States Department of Astronomy Ohio State University 140 West 18th Avenue ColumbusOH43210 United States Center for Cosmology and AstroParticle Physics Ohio State University 191 W. Woodruff Ave. ColumbusOH43210 United States Observatories of the Carnegie Institution for Science 813 Santa Barbara St. PasadenaCA91101 United States School of Physics University of Melbourne ParkvilleVIC3010 Australia Department of Astronomy and Astrophysics University of California Santa CruzCA95064 United States DARK Niels Bohr Institute University of Copenhagen Lyngbyvej 2 Copenhagen2100 Denmark Institute for Astronomy University of Hawai'i 34 Ohia Ku St. PukalaniHI96768 United States Coral Towers Observatory CairnsQLD4870 Australia Dogsheaven Observatory SMPW Q25CJ1 LT10B Brasilia Brazil Moondyne Observatory Bakers HillWA Australia Department of Physics Kavli Institute for Astrophysics and Space Research Massachusetts Institute of Technology CambridgeMA02139 United States Department of Physics Earth Science and Space System Engineering Morehead State University 235 Martindale Dr MoreheadKY40351 United States Bronberg Observatory Center for Backyard Astrophysics Pretoria PO Box 11426 Tiegerpoort0056 South Africa Kleinkaroo Observatory Center for Backyard Astrophysics Kleinkaroo Sint Helena 1B PO Box 281 Calitzdorp6660 South Africa Núcleo de Astronomía de la Facultad de Ingeniería y Ciencias Universidad Diego Portales Av. Ejército 441 Santiago Chile Millennium Institute of Astrophysics Santiago Chile US Naval Observatory Flagstaff Station P.O. Box 1149 FlagstaffAZ86002 United States Department of Physics and Astronomy George Mason University MS3F3 4400 University Drive FairfaxVA22030 United States Carnegie Institution for Science Earth and Planets Laboratory 5241 Broad Branch Road WashingtonDC20015 United States

We present the discovery that ASASSN-14ko is a periodically flaring AGN at the center of the galaxy ESO 253−G003. At the time of its discovery by the All-Sky Automated Survey for Supernovae (ASAS-SN), it was classified as a supernova close to the nucleus. The subsequent six years of V- and g-band ASAS-SN observations reveal that ASASSN-14ko has nuclear flares occurring at regular intervals. The seventeen observed outbursts show evidence of a decreasing period over time, with a mean period of P0 = 114.2 ±0.4 days and a period derivative of Ṗ = −0.0017 ±0.0003. The most recent outburst in May 2020, which took place as predicted, exhibited spectroscopic changes during the rise and a had a UV bright, blackbody spectral energy distribution similar to tidal disruption events (TDEs). The X-ray flux decreased by a factor of 4 at the beginning of the outburst and then returned to its quiescent flux after ∼ 8 days. TESS observed an outburst during Sectors 4-6, revealing a rise time of 5.60±0.05 days in the optical and a decline that is best fit with an exponential model. We discuss several possible scenarios to explain ASASSN-14ko's periodic outbursts, but currently favor a repeated partial TDE. The next outbursts should peak in the optical on UT 2020-09-7.4 ± 1.1 and UT 2020-12-26.5 ± 1.4. Copyright © 2020, The Authors. All rights reserved.

关键词： Supernovae

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The evolution of disk winds from a combined study of optical and infrared forbidden lines

arXiv

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arXiv 2020年

作者： Pascucci, Ilaria Banzatti, Andrea Gorti, Uma Fang, Min Pontoppidan, Klaus Alexander, Richard Ballabio, Giulia Edwards, Suzan Salyk, Colette Sacco, Germano Flaccomio, Ettore Blake, Geoffrey A. Carmona, Andres Hall, Cassandra Kamp, Inga Käufl, Hans Ulrich Meeus, Gwendolyn Meyer, Michael Pauly, Tyler Steendam, Simon Sterzik, Michael Lunar and Planetary Laboratory University of Arizona TucsonAZ85721 United States Earths in Other Solar Systems Team NASA Nexus for Exoplanet System Science Department of Physics Texas State University 749 N Comanche Street San MarcosTX78666 United States SETI Institute NASA Ames Research Center Mail Stop 245-3 Moffett FieldCA94035-1000 United States California Institute of Technology Cahill Center for Astronomy and Astrophysics MC 249-17 PasadenaCA91125 United States Space Telescope Science Institute 3700 San Martin Drive BaltimoreMD21218 United States School of Physics and Astronomy University of Leicester LeicesterLE1 7RH United Kingdom Five College Astronomy Department Smith College NorthamptonMA01063 United States Department of Physics and Astronomy Vassar College 124 Raymond Avenue PoughkeepsieNY12604 United States INAF Osservatorio Astrofisico di Arcetri Largo E. Fermi 5 Firenze50125 Italy INAF Osservatorio Astronomico di Palermo Piazza del Parlamento 1 Palermo90134 Italy Division of Geological and Planetary Sciences California Institute of Technology PasadenaCA91125 United States Astrophysics & Planetology Research Institute 9 avenue du Colonel Roche BP 44346 Toulouse Cedex 431028 France Department of Physics and Astronomy University of Georgia AthensGA30602 United States Center for Simulational Physics University of Georgia AthensGA30602 United States Kapteyn Astronomical Institute University of Groningen Groningen Netherlands European Southern Observatory Karl-Schwarzschild-Str. 2 Garching85748 Germany Department of Theoretical Physics Autonomous of Madrid Cantoblanco Madrid28049 Spain Facultad de Ciencias UAM Madrid28049 Spain Department of Astronomy University of Michigan 311 West Hall 1085 S. University Ave Ann ArborMI48109 United States

We analyze high-resolution (∆v ≤ 10 km/s) optical and infrared spectra covering the [O I] 6300 Å and [Ne II] 12.81 µm lines from a sample of 31 disks in different evolutionary stages. Following work at optical wavelengths, we use Gaussian profiles to fit the [Ne II] lines and classify them into HVC (LVC) if the line centroid is more (less) blueshifted than 30 km/s with respect to the stellar radial velocity. Unlike for the [O I] where a HVC is often accompanied by a LVC, all 17 sources with a [Ne II] detection have either a HVC or a LVC. [Ne II] HVCs are preferentially detected toward high accretors (Ṁacc > 10−8 M☉/yr) while LVCs are found in sources with low Ṁacc, low [O I] luminosity, and large infrared spectral index (n13−31). Interestingly, the [Ne II] and [O I] LVC luminosities display an opposite behaviour with n13−31: as the inner dust disk depletes (higher n13−31) the [Ne II] luminosity increases while the [O I] weakens. The [Ne II] and [O I] HVC profiles are generally similar with centroids and FWHMs showing the expected behaviour from shocked gas in micro-jets. In contrast, the [Ne II] LVC profiles are typically more blueshifted and narrower than the [O I] profiles. The FWHM and centroid vs. disk inclination suggest that the [Ne II] LVC predominantly traces unbound gas from a slow, wide-angle wind that has not lost completely the Keplerian signature from its launching region. We sketch an evolutionary scenario that could explain the combined [O I] and [Ne II] results and includes screening of hard (∼ 1 keV) X-rays in inner, mostly molecular, MHD winds. Copyright © 2020, The Authors. All rights reserved.

关键词： Luminance

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Research on requirement elicitation model of high-end equipment based on requirement classification under Internet and big data environment

Research on requirement elicitation model of high-end equipm...

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2016 4th International Conference on Machinery,Materials and Information technology Applications(ICMMITA 2016)

作者： Yu GUO Junting WU Ke-wei YANG Lixin Yu College of Information System and Management National University of Defense Technology Science and Technology on Special System Simulation Laboratory Beijing Simulation Center

ISBN: (纸本)9781510835467

Currently, Internet and big data as the representative of emerging technologies are widely penetrated into every aspect of the high-end equipment manufacturing industry. Considering the characteristics of multi-source, personalized and potential for high-end equipment, this paper focuses on requirement elicitation in the background of Internet, and proposes a high-end equipment requirement elicitation model based on requirement classification, which stands on the perspective of management to study the high-end equipment requirement elicitation. First, we classify the user's need, and then different technical means are taken orienting different types of needs. In this paper, according to users' master degree of requirement, requirements can be divided into instant user requirement and potential user requirement. For instant user requirement, we design a requirement interaction platform based on Internet;For potential user requirement, a requirement mining model based on the open source information of the Internet is established. Eventually, a complete user requirement program is integrated. In conclusion, the idea of classifying the requirements provides a new perspective on requirement elicitation of high-end equipment.

关键词： high-end equipment Internet requirement elicitation requirement classification

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Nonlinear Optical Conversion: Highly Efficient Nonlinear Optical Conversion in Waveguiding GaSe Nanoribbons with Pump Pulses Down to a Femto-Joule Level (Advanced Optical Materials 5/2018)

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Advanced Optical Materials 2018年第5期6卷

作者： Feng Liao Yu Wang Tao Peng Jian Peng Zhaoqi Gu Huakang Yu Tao Chen Jiaxin Yu Fuxing Gu Shanghai Key Laboratory of Modern Optical System Engineering Research Center of Optical Instrument and System (Ministry of Education) University of Shanghai for Science and Technology Shanghai 200093 China School of Physics and Optoelectronics South China University of Technology Guangzhou 510641 China Key Laboratory of Space Active Opto-Electronics Technology Shanghai Institute of Technical Physics Chinese Academy of Sciences Shanghai 200083 China

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3D-Parallel Coordinates:Visualization for Time Varying Multidimensional Data

3D-Parallel Coordinates:Visualization for Time Varying Multi...

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2016 IEEE 7th International Conference on Software Engineering and Service science

作者： Yao Zhonghua Wu Lingda Science and Technology on Complex Electronic System Simulation Laboratory Equipment Academy

Parallel coordinates can visualize multidimensional data efficiently,during to its shortage in displaying time-varying data,we present a new method to add time dimension,which can extend parallel coordinates into 3D space(3D-Parallel Coordinates)consisted of attribute,range and time *** that timevarying multidimensional data can be displayed as polygonal line cluster for recording and analyzing.A technique called clipping shade is taken to highlight datasets around the current time,and results reveal that 3D-Parallel Coordinates can effectively analyze attribute's time-varying character.

关键词： parallel coordinates time-varying multidimensional data data visualization

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Temporal and spatial evolutions of a large sunspot group and great auroral storms around the carrington event in 1859

arXiv

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arXiv 2019年

作者： Hisashi, Hayakawa Ebihara, Yusuke Willis, David M. Toriumi, Shin Iju, Tomoya Hattori, Kentaro Wild, Matthew N. Oliveira, Denny M. Ermolli, Ilaria Ribeiro, José R. Correia, Ana P. Ribeiro, Ana I. Knipp, Delores J. Graduate School of Letters Osaka University JSPS Research Toyonaka5600043 Japan UK Solar System Data Centre Space Physics and Operations Division RAL Space Science and Technology Facilities Council Rutherford Appleton Laboratory Harwell Oxford Didcot OxfordshireOX11 0QX United Kingdom Research Institute for Sustainable Humanosphere Kyoto University Uji6100011 Japan Unit of Synergetic Studies for Space Kyoto University Kyoto6068306 Japan Centre for Fusion Space and Astrophysics Department of Physics University of Warwick CoventryCV4 7AL United Kingdom 3-1-1 Yoshinodai Chuo-ku Sagamihara Kanagawa252-5210 Japan National Astronomical Observatory of Japan Mitaka1818588 Japan Graduate School of Science Kyoto University Kyoto Kitashirakawa Oiwake-cho Sakyo-ku Kyoto6068502 Japan Goddard Planetary Heliophysics Institute University of Maryland Baltimore County 1000 Hilltop Circle BaltimoreMD21250 United States NASA Goddard Space Flight Center 8800 Greenbelt Road GreenbeltMD21021 United States INAF Osservatorio Astronomico di Roma Via Frascati 33 Monte Porzio Catone00078 Italy Escola Secundária Henrique Medina Esposende Av. Dr. Henrique Barros Lima Esposende4740-203 Portugal EPIUnit - Instituto de Saúde Pública Universidade do Porto Rua das Taipas Porto135 4050-600 Portugal Departamento de Ciências da Saúde Pública e Forenses e Educação Médica Faculdade de Medicina Universidade do Porto Porto4200-319 Portugal High Altitude Observatory National Center for Atmospheric Research BoulderCOCO 80307 United States Smead Aerospace Engineering Sciences Department University of Colorado Boulder BoulderCOCO 80309 United States

The Carrington event is considered to be one of the most extreme space weather events in observational history within a series of magnetic storms caused by extreme interplanetary coronal mass ejections (ICMEs) from a large and complex active region (AR) emerged on the solar disk. In this article, we study the temporal and spatial evolutions of the source sunspot active region and visual aurorae, and compare this storm with other extreme space weather events on the basis of their spatial evolution. Sunspot drawings by Schwabe, Secchi, and Carrington describe the position and morphology of the source AR at that time. Visual auroral reports from the Russian Empire, Iberia, Ireland, Oceania, and Japan fill the spatial gap of auroral visibility and revise the time series of auroral visibility in mid to low magnetic latitudes (MLATs). The reconstructed time series is compared with magnetic measurements and shows the correspondence between low to mid latitude aurorae and the phase of magnetic storms. The spatial evolution of the auroral oval is compared with those of other extreme space weather events in 1872, 1909, 1921, and 1989 as well as their storm intensity, and contextualizes the Carrington event, as one of the most extreme space weather events, but likely not unique. Copyright © 2019, The Authors. All rights reserved.

关键词： Visibility

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A Hierarchical Access Control Model of Software Repository Based on RBAC

A Hierarchical Access Control Model of Software Repository B...

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2016 IEEE 7th International Conference on Software Engineering and Service science

作者： Cen Pengrui Wu LingDa Yang Chao Yu Ronghuan Science and Technology on Complex Electronic System Simulation Laboratory Academy of Equipment

Analized the task and general form of the software management;pionted out the shortages of the software repository on *** introduced the Role-Based Access Control model(RBAC model) which was introduced into the construction of software repository service by combining with the requirement of security management about software repository.A hierarchical access control model based on RBAC was proposed,and it database of the software repository based on RBAC was *** effective application of this model in the process of software management can ensure the convenience of software distribution;and meanwhile it can effectively improve the security of the software packages.

关键词： software management access control model security

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