检索结果-内蒙古大学图书馆

arXiv 2018年

作者： Silverman, J.D. Daddi, E. Rujopakarn, W. Renzini, A. Mancini, C. Bournaud, F. Puglisi, A. Rodighiero, G. Liu, D. Sargent, M. Arimoto, N. Béthermin, M. Fensch, J. Hayward, C.C. Kartaltepe, J. Kashino, D. Koekemoer, A. Magdis, G. McCracken, H.J. Nagao, T. Sheth, K. Smolčić, V. Valentino, F. Kavli Institute for the Physics and Mathematics of the Universe University of Tokyo Kashiwa277-8583 Japan Laboratoire AIM CEA/DSM-CNRS-Universite Paris Diderot Irfu/Service d'Astrophysique CEA Saclay Department of Physics Faculty of Science Chulalongkorn University 254 Phayathai Road Pathumwan Bangkok10330 Thailand Don Kaeo Mae Rim Chiang Mai50180 Thailand Kavli Institute for the Physics and Mathematics of the Universe Todai Institutes for Advanced Study University of Tokyo Kashiwa277-8583 Japan Instituto Nazionale de Astrofisica Osservatorio Astronomico di Padova v.co dell'Osservatorio 5 PadovaI-35122 Italy Dipartimento di Fisica e Astronomia Universita di Padova vicolo Osservatorio 3 Padova35122 Italy Astronomy Centre Department of Physics and Astronomy University of Sussex BrightonBN1 9QH United Kingdom Astronomy Program Department of Physics and Astronomy Seoul National University 599 Gwanak-ro Gwanak-gu Seoul151-742 Korea Republic of Subaru Telescope 650 North A'ohoku Place Hilo Hawaii96720 United States European Southern Observatory Karl-Schwarzschild-Str. 2 Garching85748 Germany European Southern Observatory Karl-Schwarzschild-Str. 2 Garching bei München85748 Germany Center for Computational Astrophysics Flatiron Institute 162 Fifth Avenue New YorkNY10010 United States School of Physics and Astronomy Rochester Institute of Technology 84 Lomb Memorial Drive RochesterNY14623 United States Institute of Astronomy ETH Zürich Wolfgang-Pauli-Strasse 27 ZürichCH-8093 Switzerland Space Telescope Science Institute 3700 San Martin Drive BaltimoreMD21218 United States Cosmic DAWN Centre Niels Bohr Institute University of Copenhagen Juliane Mariesvej 30 Copenhagen2100 Denmark Institut d'Astrophysique de Paris CNRS UMR 7095 and UPMC 98bis boulevard Arago ParisF-75014 France Graduate School of Science and Engineering Ehime University 2-5 Bunkyo-cho Matsuyama790-8577 Japan NASA Headquaters 300 E. St SW WashingtonDC2054

We report on the discovery of a merger-driven starburst at z = 1:52, PACS-787, based on high signal-to-noise ALMA observations. CO(5-4) and continuum emission (850μm) at a spatial resolution of 0.3" reveal two compact (r1/2 ∼ 1 kpc) and interacting molecular gas disks at a separation of 8.6 kpc thus indicative of an early stage in a merger. With a SFR of 991 Mo yr-1, this starburst event should occur closer to final coalescence, as usually seen in hydrodynamical simulations. From the CO size, inclination, and velocity profile for both disks, the dynamical mass is calculated through a novel method that incorporates a calibration using simulations of galaxy mergers. Based on the dynamical mass, we measure (1) the molecular gas mass, independent from the CO luminosity, (2) the ratio of the total gas mass and the CO(1 - 0) luminosity (αCO ≡ Mgas/L'CO1-0), and (3) the gas-to-dust ratio, with the latter two being lower than typically assumed. We find that the high star formation, triggered in both galaxies, is caused by a set of optimal conditions: a high gas mass/fraction, a short depletion time (τdepl = 85 and 67 Myrs) to convert gas into stars, and the interaction of likely counter-rotating molecular disks that may accelerate the loss of angular momentum. The state of interaction is further established by the detection of di_use CO and continuum emission, tidal debris that bridges the two nuclei and is associated with stellar emission seen by HST/WFC3. This observation demonstrates the power of ALMA to study the dynamics of galaxy mergers at high redshift. Copyright © 2018, The Authors. All rights reserved.

关键词： Galaxies

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The large Trans-Neptunian Object 2002 TC302 from combined stellar occultation, photometry and astrometry data

arXiv

引用

arXiv 2020年

作者： Ortiz, J.L. Santos-Sanz, Pablo Sicardy, B. Benedetti-Rossi, G. Duffard, R. Morales, N. Braga-Ribas, F. Fernández-Valenzuela, E. Nascimbeni, V. Nardiello, D. Carbognani, A. Buzzi, L. Aletti, A. Bacci, P. Maestripieri, M. Mazzei, L. Mikuz, H. Skvarc, J. Ciabattari, F. Lavalade, F. Scarfi, G. Mari, J.M. Conjat, M. Sposetti, S. Bachini, M. Succi, G. Mancini, F. Alighieri, M. Dal Canto, E. Masucci, M. Vara-Lubiano, M. Gutiérrez, P.J. Desmars, J. Lecacheux, J. Vieira-Martins, R. Camargo, J.I.B. Assafin, M. Colas, F. Beisker, W. Behrend, R. Mueller, T.G. Meza, E. Gomes-Junior, A.R. Roques, F. Vachier, F. Mottola, S. Hellmich, S. Bagatin, A. Campo Alvarez-Candal, A. Cikota, S. Cikota, A. Christille, J.M. Pál, A. Kiss, C. Pribulla, T. Komžík, R. Madiedo, J.M. Charmandaris, V. Alikakos, J. Szakáts, R. Farkas-Takács, A. Varga-Verebélyi, E. Marton, G. Marciniak, A. Bartczak, P. Butkiewicz-BĄk, M. Dudziński, G. Alí-Lagoa, V. Gazeas, K. Paschalis, N. Tsamis, V. Guirado, J.C. Peris, V. Iglesias-Marzoa, R. Schnabel, C. Manzano, F. Navarro, A. Perelló, C. Vecchione, A. Noschese, A. Morrone, L. Instituto de Astrofísica de Andalucía IAA-CSIC Glorieta de la Astronomía s/n Granada18008 Spain LESIA Observatoire de Paris Université PSL CNRS Sorbonne Université Université de Paris 5 place Jules Janssen Meudon92195 France Laboratório Interinstitucional de e-Astronomia - LIneA Rua Gal. José Cristino 77 Rio de Janeiro RJ20921-400 Brazil Curitiba Brazil Observatório Nacional MCTIC Rio de Janeiro Brazil Florida Space Institute University of Central Florida 12354 Research Parkway Partnership 1 OrlandoFL United States Dipartimento di Fisica e Astronomia ’G. Galilei’ Universita degli Studi di Padova Padova Italy INAF-Osservatorio Astronomico di Padova Padova Italy Aix Marseille Univ CNRS CNES LAM Marseille France INAF - Osservatorio di Astrofisica e Scienza dello Spazio Bologna Italy Schiaparelli Astronomical Observatory Varese Italy Astronomical Observatory San Marcello Pistoiese CARA Project Italy Crni Vrh Observatory Crni Vrh nad Idrijo Slovenia Faculty of Mathematics and Physics University of Ljubljana Slovenia Osservatorio Astronomico di Monte Agliale Lucca Italy Vinon sur Verdon 83560 France Observatorio Astronomico Iota-Scorpii La Spezia Italy Biot 06410 France Observatoire de la Côte d’Azur France Gnosca 6525 Switzerland Osservatorio Astronomico di Tavolaia Pisa Italy Institut Polytechnique des Sciences Avancées IPSA 63 boulevard de Brandebourg Ivry-sur-SeineF-94200 France Institut de Mécanique Céleste et de Calcul des Éphémérides IM-CCE Observatoire de Paris PSL Research University CNRS Sorbonne Universités UPMC Univ Paris 06 Univ. Lille 77 Av. Denfert-Rochereau ParisF-75014 France Observatório do Valongo/UFRJ Rio de Janeiro Brazil Germany Observatoire de Geneve Sauverny Switzerland Garching Germany UNESP - São Paulo State University Grupo de Dinâmica Orbital e Planetologia Guaratinguetá SP12516-410 Brazil Institute of Planetary Research Berlin Germany DFISTS Universidad de Alicante Spain IUFACyT Unversidad de Al

Context. Deriving physical properties of Trans-Neptunian Objects is important for the understanding of our solar system. This requires observational efforts and the development of techniques suitable for these studies. Aims. Our aim was to characterize the large Trans-Neptunian Object 2002 TC302 Methods. Stellar occultations offer unique opportunities to determining key physical properties of Trans-Neptunian Objects. On 28th January 2018, the large Trans-Neptunian Object 2002 TC302 occulted a mv ∼ 15.3 star with designation 593-005847 in the UCAC4 stellar catalog, corresponding to Gaia source 130957813463146112. Twelve positive occultation chords were obtained from Italy, France, Slovenia and Switzerland. Also, four negative detections were obtained near the north and south limbs. This represents the best observed stellar occultation by a Trans-Neptunian Object other than Pluto, in terms of the number of chords published thus far. From the twelve chords, an accurate elliptical fit to the instantaneous projection of the body, compatible with the near misses, can be obtained. Results. The resulting ellipse has major and minor axes of 543 ± 18 km and 460 ± 11 km, respectively, with a position angle of 3 ± 1 degrees for the minor axis. This information, combined with rotational light curves obtained with the 1.5-m telescope at Sierra Nevada Observatory and the 1.23-m telescope at Calar Alto observatory, allows us to derive possible three-dimensional shapes and density estimations for the body, based on hydrostatic equilibrium assumptions. The effective diameter in equivalent area is around 84 km smaller than the radiometrically derived diameter using thermal data from Herschel and Spitzer Space Telescopes. This might indicate the existence of an unresolved satellite of up to ∼ 300 km in diameter, to account for all the thermal flux, although the occultation and thermal diameters are compatible within their error bars given the considerable uncertainty of the thermal res

关键词： Photometry

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Equation of state dependent dynamics and multimessenger signals from stellar-mass black hole formation

arXiv

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arXiv 2017年

作者： Pan, Kuo-Chuan Liebendörfer, Matthias Couch, Sean M. Thielemann, Friedrich-Karl Department of Physics and Astronomy Michigan State University East LansingMI48824 United States Joint Institute for Nuclear Astrophysics Michigan State University East LansingMI48824 United States Departement Physik Universität Basel Klingelbergstrasse 82 BaselCH-4056 Switzerland Department of Computational Mathematics Science and Engineering Michigan State University East LansingMI48824 United States National Superconducting Cyclotron Laboratory Michigan State University East LansingMI48824 United States

We investigate axisymmetric black hole (BH) formation and its gravitational wave (GW) and neutrino signals with self-consistent core-collapse supernova simulations of a non-rotating 40 M☉ progenitor star using the isotropic diffusion source approximation for the neutrino transport and a modified gravitational potential for general relativistic effects. We consider four different neutron star (NS) equations of state (EoS): LS220, SFHo, BHBΛφ and DD2, and study the impact of the EoS on BH formation dynamics and GW emission. We find that the BH formation time is sensitive to the EoS from 460 to > 1300 ms and is delayed in multiple dimensions for ∼ 100 − 250 ms due to the finite entropy effects. Depending on the EoS, our simulations show the possibility that shock revival can occur along with the collapse of the proto-neutron star (PNS) to a BH. The gravitational waveforms contain four major features that are similar to previous studies but show extreme values: (1) a low frequency signal (∼ 300 − 500 Hz) from core-bounce and prompt convection, (2) a strong signal from the PNS g-mode oscillation among other features, (3) a high frequency signal from the PNS inner-core convection, and (4) signals from the standing accretion shock instability and convection. The peak frequency at the onset of BH formation reaches to ∼ 2.3 kHz. The characteristic amplitude of a 10 kpc object at peak frequency is detectable but close to the noise threshold of the Advanced LIGO and KAGRA, suggesting that the next generation gravitational wave detector will need to improve the sensitivity at the kHz domain to better observe stellar-mass BH formation from core-collapse supernovae or failed supernovae. Copyright © 2017, The Authors. All rights reserved.

关键词： Gravity waves

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Tracking origins of below-threshold harmonics with a trajectory-resolved fully quantum approach

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Physical Review A 2016年第6期94卷 063417-063417页

作者： Rui-Hua Xu Yan-Jun Chen Jie Liu Li-Bin Fu National Laboratory of Science and Technology on Computational Physics Institute of Applied Physics and Computational Mathematics Beijing 100088 China Graduate School China Academy of Engineering Physics Beijing 100088 China College of Physics and Information Technology Shaan'xi Normal University Xi'an China HEDPS Center for Applied Physics and Technology Peking University Beijing 100084 China

The emission of below-threshold harmonics (BTHs) is a promising tool for producing vacuum-ultraviolet frequency combs. Nevertheless, the generation mechanism of BTHs is still an open question and a lot of efforts have been devoted to this issue. Here, with a developed trajectory-resolved fully quantum numerical scheme which allows us to “coherently” trace the motion of the rescattering electron, the complex roles of different rescattering trajectories, such as the first return or multiple returns in the origin of BTHs are identified unambiguously. We show that the emission of BTHs is influenced dramatically by laser intensity. At strong laser fields, multiple returns (especially the third return) play an important role in BTHs. At weak fields, effects related to multiphoton processes dominate. The interference of the different contributions to BTHs is also addressed.

关键词： Atomic & molecular processes in external fields High-order harmonic generation

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Short-distance matrix elements for D0-meson mixing from Nf=2+1 lattice QCD

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Physical Review D 2018年第3期97卷 034513-034513页

作者： A. Bazavov C. Bernard C. M. Bouchard C. C. Chang C. DeTar D. Du A. X. El-Khadra E. D. Freeland E. Gámiz Steven Gottlieb U. M. Heller A. S. Kronfeld J. Laiho P. B. Mackenzie E. T. Neil J. N. Simone R. Sugar D. Toussaint R. S. Van de Water R. Zhou Department of Computational Mathematics Science and Engineering Department of Physics and Astronomy Michigan State University East Lansing Michigan 48824 USA Department of Physics Washington University St. Louis Missouri 63130 USA School of Physics and Astronomy University of Glasgow Glasgow G12 8QQ United Kingdom Department of Physics University of Illinois Urbana Illinois 61801 USA Fermi National Accelerator Laboratory Batavia Illinois 60510 USA Department of Physics and Astronomy University of Utah Salt Lake City Utah 84112 USA Department of Physics Syracuse University Syracuse New York 13244 USA Liberal Arts Department School of the Art Institute of Chicago Chicago Illinois 60603 USA CAFPE and Departamento de Física Teórica y del Cosmos Universidad de Granada 18071 Granada Spain Department of Physics Indiana University Bloomington Indiana 47405 USA American Physical Society Ridge New York 11961 USA Institute for Advanced Study Technische Universität München 85748 Garching Germany Department of Physics University of Colorado Boulder Colorado 80309 USA RIKEN-BNL Research Center Brookhaven National Laboratory Upton New York 11973 USA Department of Physics University of California Santa Barbara California 93016 USA Department of Physics University of Arizona Tucson Arizona 85721 USA

We calculate in three-flavor lattice QCD the short-distance hadronic matrix elements of all five ΔC=2 four-fermion operators that contribute to neutral D-meson mixing both in and beyond the Standard Model. We use the MILC Collaboration’s Nf=2+1 lattice gauge-field configurations generated with asqtad-improved staggered sea quarks. We also employ the asqtad action for the valence light quarks and use the clover action with the Fermilab interpretation for the charm quark. We analyze a large set of ensembles with pions as light as Mπ≈180 MeV and lattice spacings as fine as a≈0.045 fm, thereby enabling good control over the extrapolation to the physical pion mass and continuum limit. We obtain for the matrix elements in the MS¯−NDR scheme using the choice of evanescent operators proposed by Beneke et al., evaluated at 3 GeV, ⟨D0|Oi|D¯0⟩={0.0805(55)(16),−0.1561(70)(31),0.0464(31)(9),0.2747(129)(55),0.1035(71)(21)} GeV4 (i=1–5). The errors shown are from statistics and lattice systematics, and the omission of charmed sea quarks, respectively. To illustrate the utility of our matrix-element results, we place bounds on the scale of CP-violating new physics in D0 mixing, finding lower limits of about 10–50×103 TeV for couplings of O(1). To enable our results to be employed in more sophisticated or model-specific phenomenological studies, we provide the correlations among our matrix-element results. For convenience, we also present numerical results in the other commonly used scheme of Buras, Misiak, and Urban.

关键词： Flavor changing neutral currents Form factors Charmed mesons Lattice QCD

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Lattice computation of the electromagnetic contributions to kaon and pion masses

arXiv

引用

arXiv 2018年

作者： Basak, S. Bazavov, A. Bernard, C. DeTar, C. Levkova, L. Freeland, E. Gottlieb, Steven Torok, A. Heller, U.M. Laiho, J. Osborn, J. Sugar, R.L. Toussaint, D. van de Water, R.S. Zhou, R. School of Physical Sciences NISER Bhubaneswar Orissa752050 India Department of Computational Mathematics Science and Engineering Department of Physics and Astronomy Michigan State University East LansingMI48824 United States Department of Physics Washington University St. LouisMO63130 United States Department of Physics and Astronomy University of Utah Salt Lake CityUT84112 United States Liberal Arts Department School of the Art Institute of Chicago ChicagoIL60603 United States Department of Physics Indiana University BloomingtonIN47405 United States American Physical Society One Research Road RidgeNY11961 United States Department of Physics Syracuse University SyracuseNY13244 United States ALCF Argonne National Laboratory ArgonneIL60439 United States Physics Department University of California Santa BarbaraCA93106 United States Physics Department University of Arizona TucsonAZ85721 United States Theoretical Physics Department Fermi National Accelerator Laboratory Batavia60510 United States

We present a lattice calculation of the electromagnetic (EM) effects on the masses of light pseudoscalar mesons. The simulations employ 2+1 dynamical flavors of asqtad QCD quarks, and quenched photons. Lattice spacings vary from ≈0.12 fm to ≈0.045 fm. We compute the quantity Ε, which parameterizes the corrections to Dashen’s theorem for the K+–K0 EM mass splitting, as well as ΕK0, which parameterizes the EM contribution to the mass of the K0 itself. An extension of the nonperturbative EM renormalization scheme introduced by the BMW group is used in separating EM effects from isospin-violating quark mass effects. We correct for leading finite-volume effects in our realization of lattice electrodynamics in chiral perturbation theory, and remaining finite-volume errors are relatively small. While electroquenched effects are under control for Ε, they are estimated only qualitatively for ΕK0, and constitute one of the largest sources of uncertainty for that quantity. We find Ε = 0.78(1)stat(+−118)syst and ΕK0 = 0.035(3)stat(20)syst. We then use these results on 2+1+1 flavor pure QCD highly improved staggered quark (HISQ) ensembles and find mu/md = 0.4529(48)stat(+150−67)syst. Copyright © 2018, The Authors. All rights reserved.

关键词： Hadrons

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The impact of different neutrino transport methods on multidimensional core-collapse supernova simulations

arXiv

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arXiv 2018年

作者： Pan, Kuo-Chuan Mattes, Carlos O’Connor, Evan P. Couch, Sean M. Perego, Albino Arcones, Almudena Department of Physics and Astronomy Michigan State University East LansingMI48824 United States Joint Institute for Nuclear Astrophysics Center for the Evolution of the Elements Michigan State University East LansingMI48824 United States Department of Physics Institute of Astronomy National Tsing Hua University Hsinchu Taiwan Institut für Kernphysik Technische Universität Darmstadt Schlossgartenstrasse 9 DarmstadtD-64289 Germany Department of Astronomy Oskar Klein Centre Stockholm University AlbaNova StockholmSE-106 91 Sweden Department of Computational Mathematics Science and Engineering Michigan State University East LansingMI48824 United States National Superconducting Cyclotron Laboratory Michigan State University East LansingMI48824 United States Istituto Nazionale di Fisica Nucleare Sezione Milano Bicocca Gruppo collegato di Parma ParmaI-43124 Italy Università degli Studi di Milano-Bicocca Dipartimento di Fisica Piazza della Scienza 3 Milano20126 Italy GSI Helmholtzzentrum für Schwerionenforschung GmbH Planckstr. 1 Darmstadt64291 Germany

Neutrinos play a crucial role in the core-collapse supernova (CCSN) explosion mechanism. The requirement of accurately calculating the transport of neutrinos makes simulations of the CCSN mechanism extremely challenging and computationally expensive. Historically, this stiff challenge has been met by making approximations to the full transport equation. In this work, we compare CCSN simulations in one- and two-dimensions with three approximate neutrino transport schemes, each implemented in the FLASH simulation framework. We compare a two moment M1 scheme with an analytic closure (M1), the Isotropic Diffusion Source Approximation (IDSA), and the Advanced Spectral Leakage (ASL) method. We identify and discuss the advantages and disadvantages of each scheme. For each approximate transport scheme, we use identical grid setups, hydrodynamics, and gravity solvers to investigate the transport effects on supernova shock dynamics and neutrino quantities. We find that the transport scheme has a small effect on the evolution of protoneutron star (PNS) radius, PNS mass, and the mass accretion rate. The neutrino luminosities, mean energies, and shock radii have a ∼ 10-20% quantitative difference but the overall qualitative trends are fairly consistent between all three approximations. We find larger differences in the gain region properties, including the gain region mass and the net heating rate in the gain region, as well as the strength of PNS convection in the core. We investigate the progenitor, nuclear equation of state, and stochastic perturbation dependence of our simulations and find similar magnitudes of impact on key quantities. We also compare the computational expense of the various approximations. Copyright © 2018, The Authors. All rights reserved.

关键词： Supernovae

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Online Machine Learning for Big Data Analytics by Cognitive Robots

Online Machine Learning for Big Data Analytics by Cognitive ...

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2016 IEEE International Conference of Online Analysis and computing science(ICOACS 2016)

作者： Yingxu Wang FICIC FWIF Information Systems Lab Stanford University Laboratory for Computational Intelligence Denotational Mathematicsand Software Science Dept.of Electrical and Computer EngineeringSchulich School of Engineering and Hotchkiss Brain InstituteUniversity of Calgary

It is recognized that both sources of and solutions to the big data challenges are human collective *** are an abstract representation of the quantity of realistic entities and perceived *** data play an indispensable role not only in a wide range of engineering applications,but also in the cognitive mechanisms of both humans and cognitive robots such as sensation,quantification,qualification,estimation,memory,and *** keynote lecture presents online big data analytic theories by machine learning as well as knowledge extraction by cognitive ***,information,knowledge,and intelligence are the four hierarchical layers of cognitive objects in the brain and cognitive systems from the bottom *** is discovered by the author that,although the cognitive unit of data is bit,that of knowledge is bir,i.e.,a binary relation.A resent finding towards big data science is that big data systems in nature are a recursive ndimensional typed hyperstructure(RNDTHS).This topological property of big data reveals that the mathematical foundation of big data science is underpinned by big data algebra(BDA),which is a denotational mathematical structure for efficiently dealing with the inherited complexities and unprecedented challenges in big data *** leads to a coherent theory for big data modeling,analyses,mining,information elicitation,knowledge extraction,and intelligent generation for cognitive *** experiments demonstrate that cognitive robots may autonomously transform big data in vast linguistic databases(corpuses) into sophistic knowledge bases by cognitive machine learning.

关键词： Big data big data science denotational mathematics mathematical models recursively hierarchical hyperstructures big data algebra cogniitve machine learning formal concepts knowledge extraction knowledge generation cognitive informatics cognitive computing computational intelligence applications

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Comprehensive Analysis of Hd 105, A Young Solar System Analog

arXiv

引用

arXiv 2018年

作者： Marshall, J.P. Milli, J. Choquet, É. Del Burgo, C. Kennedy, G.M. Matrà, L. Ertel, S. Boccaletti, A. Academia Sinica Institute of Astronomy and Astrophysics 11F of AS/NTU Astronomy-Mathematics Building No.1 Sect. 4 Roosevelt Rd Taipei10617 Taiwan Alonso de Córdova 3107 Vitacura Casilla Santiago19001 Chile Department of Astronomy California Institute of Technology 1200 E. California Blvd MC 249-17 PasadenaCA91125 United States Instituto Nacional de Astrofísica Óptica y Electrónica Luis Enrique Erro 1 Sta. Ma. Tonantzintla Puebla Mexico Department of Physics University of Warwick CoventryCV4 7AL United Kingdom Harvard-Smithsonian Center for Astrophysics 60 Garden Street CambridgeMA02138 United States Steward Observatory University of Arizona 933 N Cherry Ave TucsonAZ85719 United States LESIA Observatoire de Paris PSL Research University CNRS Sorbonne Universités UPMC Univ. Paris 06 Univ. Paris Diderot Sorbonne Paris Cité Computational Engineering and Science Research Centre University of Southern Queensland ToowoombaQLD4350 Australia Jet Propulsion Laboratory California Institute of Technology 4800 Oak Grove Drive PasadenaCA91109 United States

HD 105 is a nearby, pre-main sequence G0 star hosting a moderately bright debris disc (Ldust/L? ∼ 2.6 ×10−4). HD 105 and its surroundings might therefore be considered an analogue of the young Solar System. We refine the stellar parameters based on an improved Gaia parallax distance, identify it as a pre-main sequence star with an age of 50 ± 16 Myr. The circumstellar disc was marginally resolved by Herschel/PACS imaging at far-infrared wavelengths. Here we present an archival ALMA observation at 1.3 mm, revealing the extent and orientation of the disc. We also present HST/NICMOS and VLT/SPHERE near-infrared images, where we recover the disc in scattered light at the ≥ 5-σ level. This was achieved by employing a novel annular averaging technique, and is the first time this has been achieved for a disc in scattered light. Simultaneous modelling of the available photometry, disc architecture, and detection in scattered light allow better determination of the disc’s architecture, and dust grain minimum size, composition, and albedo. We measure the dust albedo to lie between 0.19 and 0.06, the lower value being consistent with Edgeworth-Kuiper belt objects. Copyright © 2018, The Authors. All rights reserved.

关键词： Light scattering

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Exploring outliers in crowdsourced ranking for QoE

arXiv

引用

arXiv 2017年

作者： Xu, Qianqian Yan, Ming Huang, Chendi Xiong, Jiechao Huang, Qingming Yao, Yuan Institute of Information Engineering Cas Beijing100093 Department of Computational Mathematics Michigan State University East LansingMI48824 United States BICMR-LMAM-LMEQF-LMP School of Mathematical Sciences Peking University Beijing100871 Tencent Ai Lab Shenzhen518057 University of Chinese Academy of Sciences Beijing100049 China Key Lab of Intell. Info. Process. Inst. of Comput. Tech. Cas Beijing100190 Key Lab of Big Data Mining and Knowledge Management Cas Beijing100190 Department of Mathematics Hong Kong University of Science and Technology 100871 Hong Kong

Outlier detection is a crucial part of robust evaluation for crowd-sourceable assessment of Quality of Experience (QoE) and has attracted much attention in recent years. In this paper, we propose some simple and fast algorithms for outlier detection and robust QoE evaluation based on the nonconvex optimization principle. Several iterative procedures are designed with or without knowing the number of outliers in samples. Theoretical analysis is given to show that such procedures can reach statistically good estimates under mild conditions. Finally, experimental results with simulated and real-world crowdsourcing datasets show that the proposed algorithms could produce similar performance to Huber-LASSO approach in robust ranking, yet with nearly 8 or 90 times speed-up, without or with a prior knowledge on the sparsity size of outliers, respectively. Therefore the proposed methodology provides us a set of helpful tools for robust QoE evaluation with crowdsourcing data. Copyright © 2017, The Authors. All rights reserved.

关键词： Crowdsourcing

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