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Generalisation enhancement via input space transformation: A GP approach 17

17th European Conference on Genetic Programming, EuroGP 2014

作者： Kattan, Ahmed Kampouridis, Michael Agapitos, Alexandros Um Al Qura University AI Real-World Applications Lab Department of Computer Science Saudi Arabia University of Kent School of Computing United Kingdom Complex and Adaptive Systems Laboratory School of Computer Science and Informatics University College Dublin Ireland

ISBN: (纸本)9783662443026

This paper proposes a new approach to improve generalisation of standard regression techniques when there are hundreds or thousands of input variables. The input space X is composed of observational data of the form (xi, y(xi)), i = 1…n where each xi denotes a k-dimensional input vector of design variables and y is the response. Genetic Programming (GP) is used to transform the original input space X into a new input space Z = (zi, y(zi)) that has smaller input vector and is easier to be mapped into its corresponding responses. GP is designed to evolve a function that receives the original input vector from each xi in the original input space as input and return a new vector zi as an output. Each element in the newly evolved zi vector is generated from an evolved mathematical formula that extracts statistical features from the original input space. To achieve this, we designed GP trees to produce multiple outputs. Empirical evaluation of 20 different problems revealed that the new approach is able to significantly reduce the dimensionality of the original input space and improve the performance of standard approximation models such as Kriging, Radial Basis Functions Networks, and Linear Regression, and GP (as a regression techniques). In addition, results demonstrate that the new approach is better than standard dimensionality reduction techniques such as Principle Component Analysis (PCA). Moreover, the results show that the proposed approach is able to improve the performance of standard Linear Regression and make it competitive to other stochastic regression techniques. © Springer-Verlag Berlin Heidelberg 2014.

关键词： Genetic programming

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Fermi-lat observations of high-energy behind-the-limb solar flares

arXiv

引用

arXiv 2017年

作者： Ackermann, M. Allafort, A. Baldini, L. Barbiellini, G. Bastieri, D. Bellazzini, R. Bissaldi, E. Bonino, R. Bottacini, E. Bregeon, J. Bruel, P. Buehler, R. Cameron, R.A. Caragiulo, M. Caraveo, P.A. Cavazzuti, E. Cecchi, C. Charles, E. Ciprini, S. Costanza, F. Cutini, S. D'Ammando, F. de Palma, F. Desiante, R. Digel, S.W. Di Lalla, N. Di Mauro, M. Di Venere, L. Drell, P.S. Favuzzi, C. Fukazawa, Y. Fusco, P. Gargano, F. Giglietto, N. Giordano, F. Giroletti, M. Grenier, I.A. Guillemot, L. Guiriec, S. Jogler, T. Jóhannesson, G. Kashapova, L. Krucker, S. Kuss, M. la Mura, G. Larsson, S. Latronico, L. Li, J. Liu, W. Longo, F. Loparco, F. Lubrano, P. Magill, J.D. Maldera, S. Manfreda, A. Mazziotta, M.N. Mitthumsiri, W. Mizuno, T. Monzani, M.E. Morselli, A. Moskalenko, I.V. Negro, M. Nuss, E. Ohsugi, T. Omodei, N. Orlando, E. Pal'shin, V. Paneque, D. Perkins, J.S. Pesce-Rollins, M. Petrosian, V. Piron, F. Principe, G. Rainò, S. Rando, R. Razzano, M. Reimer, O. Rubio da Costa, F. Sgrò, C. Simone, D. Siskind, E.J. Spada, F. Spandre, G. Spinelli, P. Tajima, H. Thayer, J.B. Torres, D.F. Troja, E. Vianello, G. Deutsches Elektronen Synchrotron DESY ZeuthenD-15738 Germany W. W. Hansen Experimental Physics Laboratory Kavli Institute for Particle Astrophysics and Cosmology Department of Physics SLAC National Accelerator Laboratory Stanford University StanfordCA94305 United States Università di Pisa Istituto Nazionale di Fisica Nucleare Sezione di Pisa PisaI-56127 Italy Istituto Nazionale di Fisica Nucleare Sezione di Trieste TriesteI-34127 Italy Dipartimento di Fisica Università di Trieste TriesteI-34127 Italy Istituto Nazionale di Fisica Nucleare Sezione di Padova PadovaI-35131 Italy Dipartimento di Fisica e Astronomia "G. Galilei" Università di Padova PadovaI-35131 Italy Istituto Nazionale di Fisica Nucleare Sezione di Pisa PisaI-56127 Italy Istituto Nazionale di Fisica Nucleare Sezione di Bari BariI-70126 Italy Istituto Nazionale di Fisica Nucleare Sezione di Torino TorinoI-10125 Italy Dipartimento di Fisica Università degli Studi di Torino TorinoI-10125 Italy Laboratoire Univers et Particules de Montpellier Université Montpellier CNRS IN2P3 MontpellierF-34095 France Laboratoire Leprince-Ringuet École polytechnique CNRS IN2P3 PalaiseauF-91128 France Dipartimento di Fisica "M. Merlin" dell'Università e del Politecnico di Bari BariI-70126 Italy INAF-Istituto di Astrofisica Spaziale e Fisica Cosmica Milano via E. Bassini 15 MilanoI-20133 Italy Science Data Center RomaI-00133 Italy Istituto Nazionale di Fisica Nucleare Sezione di Perugia PerugiaI-06123 Italy Dipartimento di Fisica Università degli Studi di Perugia PerugiaI-06123 Italy INAF Istituto di Radioastronomia BolognaI-40129 Italy Dipartimento di Astronomia Università di Bologna BolognaI-40127 Italy Università Telematica Pegaso Piazza Trieste e Trento 48 NapoliI-80132 Italy Università di Udine UdineI-33100 Italy Department of Physical Sciences Hiroshima University Higashi-Hiroshima Hiroshima739-8526 Japan Laboratoire AIM CEA IRFU CNRS Université Paris Diderot Servic

We report on the Fermi-LAT detection of high-energy emission from the behind-the-limb solar flares that occurred on 2013 October 11, 2014 January 6 and 2014 September 1. The Fermi-LAT observations are associated with flares from active regions originating behind both the eastern and western limbs, as determined by STEREO. All three flares are associated with very fast Coronal Mass Ejections (CMEs) and strong Solar Energetic Particle events. We present updated localizations of the > 100 MeV photon emission, hard X-ray (HXR) and EUV images and broad-band spectra from 10 keV to 10 GeV as well as microwave spectra. We also provide a comparison of the behind-the-limb flares detected by the Fermi-LAT with three on-disk flares and present a study of some of the significant quantities of these flares as an attempt to better understand the acceleration mechanisms at work during these occulted flares. We interpret the HXR emission to be due to electron bremsstrahlung from a coronal thin-target loop-top with the accelerated electron spectra steepening at semirelativistic energies. The > 100 MeV gamma-rays are best described by a pion decay model resulting from interaction of protons (and other ions) in a thick target photospheric source. The protons are believed to have been accelerated (to energies > 10 GeV) in the CME environment and precipitate down to the photosphere from the down-stream side of the CME shock and landed on the front side of the Sun, away from the original flare site and the HXR emission. Copyright © 2017, The Authors. All rights reserved.

关键词： Gamma rays

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GAMMA-RAY BLAZARS WITHIN THE FIRST 2 BILLION YEARS

arXiv

引用

arXiv 2017年

作者： Ackermann, M. Ajello, M. Baldini, L. Ballet, J. Barbiellini, G. Bastieri, D. Becerra Gonzalez, J. Bellazzini, R. Bissaldi, E. Blandford, R.D. Bloom, E.D. Bonino, R. Bottacini, E. Bregeon, J. Bruel, P. Buehler, R. Buson, S. Cameron, R.A. Caragiulo, M. Caraveo, P.A. Cavazzuti, E. Cecchi, C. Cheung, C.C. Chiang, J. Chiaro, G. Ciprini, S. Conrad, J. Costantin, D. Costanza, F. Cutini, S. D’Ammando, F. Palma, F.D.E. Desiante, R. Digel, S.W. Lalla, N.D.I. Mauro, M.D.I. Venere, L.D.I. Domínguez, A. Drell, P.S. Favuzzi, C. Fegan, S.J. Ferrara, E.C. Finke, J. Focke, W.B. Fukazawa, Y. Funk, S. Fusco, P. Gargano, F. Gasparrini, D. Giglietto, N. Giordano, F. Giroletti, M. Green, D. Grenier, I.A. Guillemot, L. Guiriec, S. Hartmann, D.H. Hays, E. Horan, D. Jogler, T. Jóhannesson, G. Johnson, A.S. Kuss, M. Mura, G.L.A. Larsson, S. Latronico, L. Li, J. Longo, F. Loparco, F. Lovellette, M.N. Lubrano, P. Magill, J.D. Maldera, S. Manfreda, A. Marcotulli, L. Mazziotta, M.N. Michelson, P.F. Mirabal, N. Mitthumsiri, W. Mizuno, T. Monzani, M.E. Morselli, A. Moskalenko, I.V. Negro, M. Nuss, E. Ohsugi, T. Ojha, R. Omodei, N. Orienti, M. Orlando, E. Ormes, J.F. Paliya, V.S. Paneque, D. Perkins, J.S. Persic, M. Pesce-Rollins, M. Piron, F. Porter, T.A. Principe, G. Rainò, S. Rando, R. Rani, B. Razzano, M. Razzaque, S. Reimer, A. Torres, D.F. Torresi, E. Tosti, G. Troja, E. Vianello, G. Wood, K.S. Reimer, O. Romani, R.W. Sgrò, C. Simone, D. Siskind, E.J. Spada, F. Spandre, G. Spinelli, P. Stalin, C.S. Stawarz, L. Suson, D.J. Takahashi, M. Tanaka, K. Thayer, J.B. Thompson, D.J. Deutsches Elektronen Synchrotron DESY ZeuthenD-15738 Germany Department of Physics and Astronomy Clemson University Kinard Lab of Physics ClemsonSC29634-0978 United States Università di Pisa Istituto Nazionale di Fisica Nucleare Sezione di Pisa PisaI-56127 Italy Laboratoire AIM CEA-IRFU CNRS Université Paris Diderot Service d’Astrophysique CEA Saclay Gif sur YvetteF-91191 France Istituto Nazionale di Fisica Nucleare Sezione di Trieste TriesteI-34127 Italy Dipartimento di Fisica Università di Trieste TriesteI-34127 Italy Istituto Nazionale di Fisica Nucleare Sezione di Padova PadovaI-35131 Italy Dipartimento di Fisica e Astronomia "G. Galilei" Università di Padova PadovaI-35131 Italy NASA Goddard Space Flight Center GreenbeltMD20771 United States Department of Physics Department of Astronomy University of Maryland College ParkMD20742 United States Istituto Nazionale di Fisica Nucleare Sezione di Pisa PisaI-56127 Italy Istituto Nazionale di Fisica Nucleare Sezione di Bari BariI-70126 Italy W. W. Hansen Experimental Physics Laboratory Kavli Institute for Particle Astrophysics and Cosmology Department of Physics SLAC National Accelerator Laboratory Stanford University StanfordCA94305 United States Istituto Nazionale di Fisica Nucleare Sezione di Torino TorinoI-10125 Italy Dipartimento di Fisica Università degli Studi di Torino TorinoI-10125 Italy Laboratoire Univers et Particules de Montpellier Université Montpellier CNRS/IN2P3 MontpellierF-34095 France Laboratoire Leprince-Ringuet École polytechnique CNRS/IN2P3 PalaiseauF-91128 France NASA Postdoctoral Program Fellow United States Dipartimento di Fisica "M. Merlin" dell’Università e del Politecnico di Bari BariI-70126 Italy INAF-Istituto di Astrofisica Spaziale e Fisica Cosmica Milano via E. Bassini 15 MilanoI-20133 Italy Science Data Center RomaI-00133 Italy Istituto Nazionale di Fisica Nucleare Sezione di Perugia PerugiaI-06123 Italy Dipartimento di Fisica Università

The detection of high-redshift (z >3) blazars enables the study of the evolution of the most luminous relativistic jets over cosmic time. More importantly, high-redshift blazars tend to host massive black holes and can be used to constrain the space density of heavy black holes in the early Universe. Here, we report the first detection with the Fermi-Large Area Telescope of five γ-ray emitting blazars beyond z = 3.1, more distant than any blazars previously detected in γ-rays. Among these five objects, NVSS J151002+570243 is now the most distant known γ-ray emitting blazar at z = 4.31. These objects have steeply falling γ-ray spectral energy distributions (SEDs) and, those that have been observed in X-rays, a very hard X-ray spectrum, both typical of powerful blazars. Their Compton dominance (ratio of the inverse Compton to synchrotron peak luminosities) is also very large (> 20). All of these properties place these objects among the most extreme members of the blazar population. Their optical spectra and the modeling of their optical-UV SEDs confirm that these objects harbor massive black holes (MBH ∼ 108−10M.). We find that, at z ≈ 4, the space density of > 109M. black holes hosted in radio-loud and radio-quiet active galactic nuclei are similar, implying that radio-loudness may play a key role in rapid black hole growth in the early Universe. Copyright © 2017, The Authors. All rights reserved.

关键词： Cosmology

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Mechanism of heuristic strategy based partition algorithm for massive semantic data flow

引用

Xitong Gongcheng Lilun yu Shijian/System Engineering Theory and Practice 2014年 34卷 248-254页

作者： Chen, Feng-Jiao Fu, Hai-Dong Wu, Gang Gu, Jin-Guang Department of Computer Science and Technology Wuhan University of Science and Technology Wuhan430065 China Hubei Province Key Laboratory of Intelligent Information Processing and Real-Time Industrial System Wuhan430065 China

The dramatic growth of massive semantic data has brought about great challenges to the distributed storage for large data. The core technology of distributed storage is graph partitioning. This paper discussed the partition mechanism for graph data flow and the strategy of partitioning heuristic function, and the partitioning algorithm and implementation process of graph data flow for the RDF file. The experiment verified the validity of the partitioning algorithm for graph data flow by comparing with METIS (a multi-level graph partitioning algorithm) and hash partitioning methods, using several true RDF datasets.

关键词： Heuristic algorithms

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Positional translation language model for ad-hoc information retrieval

Positional translation language model for ad-hoc information...

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18th Pacific-Asia Conference on Advances in Knowledge Discovery and Data Mining, PAKDD 2014

作者： Tu, Xinhui Luo, Jing Li, Bo He, Tingting Gu, Jinguang College of Computer Science and Technology Wuhan University of Science and Technology Wuhan China Hubei Province Key Laboratory of Intelligent Information Processing and Real-time Industrial System Wuhan China Department of Computer Science Central China Normal University Wuhan China State Key Lab. of Software Engineering Wuhan University Wuhan China

ISBN: (纸本)9783319066042

Most existing language modeling approaches are based on the term independence hypothesis. To go beyond this assumption, two main directions were investigated. The first one considers the use of the proximity features that capture the degree to which search terms appear close to each other in a document. Another one considers the use of semantic relationships between words. Previous studies have proven that these two types of information, including term proximity features and semantic relationships between words, are both useful to improve retrieval performance. Intuitionally, we can use them in combination to further improve retrieval performance. Based on this idea, this paper propose a positional translation language model to explicitly incorporate both of these two types of information under language modeling framework in a unified way. In the first step, we present a proximity-based method to estimate word-word translation probabilities. Then, we define a translation document model for each position of a document and use these document models to score the document. Experimental results on standard TREC collections show that the proposed model achieves significant improvements over the state-of-the-art models, including positional language model, and translation language models. © 2014 Springer International Publishing.

关键词： Information retrieval

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Search for Spectral Irregularities due to Photon–Axionlike-Particle Oscillations with the Fermi Large Area Telescope

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Physical Review Letters 2016年第16期116卷 161101-161101页

作者： M. Ajello A. Albert B. Anderson L. Baldini G. Barbiellini D. Bastieri R. Bellazzini E. Bissaldi R. D. Blandford E. D. Bloom R. Bonino E. Bottacini J. Bregeon P. Bruel R. Buehler G. A. Caliandro R. A. Cameron M. Caragiulo P. A. Caraveo C. Cecchi A. Chekhtman S. Ciprini J. Cohen-Tanugi J. Conrad F. Costanza F. D’Ammando A. de Angelis F. de Palma R. Desiante M. Di Mauro L. Di Venere A. Domínguez P. S. Drell C. Favuzzi W. B. Focke A. Franckowiak Y. Fukazawa S. Funk P. Fusco F. Gargano D. Gasparrini N. Giglietto T. Glanzman G. Godfrey S. Guiriec D. Horan G. Jóhannesson M. Katsuragawa S. Kensei M. Kuss S. Larsson L. Latronico J. Li L. Li F. Longo F. Loparco P. Lubrano G. M. Madejski S. Maldera A. Manfreda M. Mayer M. N. Mazziotta M. Meyer P. F. Michelson N. Mirabal T. Mizuno M. E. Monzani A. Morselli I. V. Moskalenko S. Murgia M. Negro E. Nuss C. Okada E. Orlando J. F. Ormes D. Paneque J. S. Perkins M. Pesce-Rollins F. Piron G. Pivato T. A. Porter S. Rainò R. Rando M. Razzano A. Reimer M. Sánchez-Conde C. Sgrò D. Simone E. J. Siskind F. Spada G. Spandre P. Spinelli H. Takahashi J. B. Thayer D. F. Torres G. Tosti E. Troja Y. Uchiyama K. S. Wood M. Wood G. Zaharijas S. Zimmer Department of Physics and Astronomy Clemson University Kinard Lab of Physics Clemson South Carolina 29634-0978 USA W. W. Hansen Experimental Physics Laboratory Kavli Institute for Particle Astrophysics and Cosmology Department of Physics and SLAC National Accelerator Laboratory Stanford University Stanford California 94305 USA Department of Physics Stockholm University AlbaNova SE-106 91 Stockholm Sweden The Oskar Klein Centre for Cosmoparticle Physics AlbaNova SE-106 91 Stockholm Sweden Università di Pisa and Istituto Nazionale di Fisica Nucleare Sezione di Pisa I-56127 Pisa Italy Istituto Nazionale di Fisica Nucleare Sezione di Trieste I-34127 Trieste Italy Dipartimento di Fisica Università di Trieste I-34127 Trieste Italy Istituto Nazionale di Fisica Nucleare Sezione di Padova I-35131 Padova Italy Dipartimento di Fisica e Astronomia “G. Galilei ” Università di Padova I-35131 Padova Italy Istituto Nazionale di Fisica Nucleare Sezione di Pisa I-56127 Pisa Italy Istituto Nazionale di Fisica Nucleare Sezione di Bari I-70126 Bari Italy Istituto Nazionale di Fisica Nucleare Sezione di Torino I-10125 Torino Italy Dipartimento di Fisica Generale “Amadeo Avogadro ” Università degli Studi di Torino I-10125 Torino Italy Laboratoire Univers et Particules de Montpellier Université Montpellier CNRS/IN2P3 Montpellier France Laboratoire Leprince-Ringuet École polytechnique CNRS/IN2P3 Palaiseau France Deutsches Elektronen Synchrotron DESY D-15738 Zeuthen Germany Consorzio Interuniversitario per la Fisica Spaziale (CIFS) I-10133 Torino Italy Dipartimento di Fisica “M. Merlin” dell’Università e del Politecnico di Bari I-70126 Bari Italy INAF-Istituto di Astrofisica Spaziale e Fisica Cosmica I-20133 Milano Italy Istituto Nazionale di Fisica Nucleare Sezione di Perugia I-06123 Perugia Italy Dipartimento di Fisica Università degli Studi di Perugia I-06123 Perugia Italy College of Science George Mason University Fairfax Virginia 22030 USA and Naval Research Laborato

We report on the search for spectral irregularities induced by oscillations between photons and axionlike-particles (ALPs) in the γ-ray spectrum of NGC 1275, the central galaxy of the Perseus cluster. Using 6 years of Fermi Large Area Telescope data, we find no evidence for ALPs and exclude couplings above 5×10−12 GeV−1 for ALP masses 0.5≲ma≲5 neV at 95% confidence. The limits are competitive with the sensitivity of planned laboratory experiments, and, together with other bounds, strongly constrain the possibility that ALPs can reduce the γ-ray opacity of the Universe.

关键词： Gamma ray astronomy Active & peculiar galaxies Axions

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Empowering planetlab: A method for TCP evaluation over the planetary-scale testbed

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Journal of Networks 2013年第2期8卷 307-316页

作者： Fraiwan, Mohammad Govindarasu, Manimaran Department of Computer Engineering Jordan University of Science and Technology Irbid 22110 Jordan Real-Time computing and Networking Lab Department of Computer Engineering Iowa State University Ames IA 50011 United States

PlanetLab, the planetary-scale overlay network, has become the de facto platform for conducting network experiments under real-life realistic conditions, scale, and geographic distribution. Many tools have been developed to manage the PlanetLab resources. However, they do not provide extra experimental capabilities to this network. Currently, PlanetLab only allows experiments at the application level, as lower levels (e.g., TCP level) are shared among all users and modifications to, for example, the TCP stack will affect all users' experiments. In this paper, we present the design of a methodology that allows researchers to implement their new TCP stack, transport algorithms, and protocols on top of PlanetLab. The approach works much like a plug-in that interacts with the PlanetLab nodes without interfering with the operating system or any other running processes. We present a research case study as an example that can make use of such a method to allow for evaluation over PlanetLab. The case study is about testing a new TCP stack, and comparing it to an existing TCP implementation under specific deployment scenarios. © 2013 ACADEMY PUBLISHER.

关键词： Geographical distribution

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Resolving the Extragalactic γ-Ray Background above 50 GeV with the Fermi Large Area Telescope

引用

Physical Review Letters 2016年第15期116卷 151105-151105页

作者： M. Ackermann M. Ajello A. Albert W. B. Atwood L. Baldini J. Ballet G. Barbiellini D. Bastieri K. Bechtol R. Bellazzini E. Bissaldi R. D. Blandford E. D. Bloom R. Bonino J. Bregeon R. J. Britto P. Bruel R. Buehler G. A. Caliandro R. A. Cameron M. Caragiulo P. A. Caraveo E. Cavazzuti C. Cecchi E. Charles A. Chekhtman J. Chiang G. Chiaro S. Ciprini J. Cohen-Tanugi L. R. Cominsky F. Costanza S. Cutini F. D’Ammando A. de Angelis F. de Palma R. Desiante S. W. Digel M. Di Mauro L. Di Venere A. Domínguez P. S. Drell C. Favuzzi S. J. Fegan E. C. Ferrara A. Franckowiak Y. Fukazawa S. Funk P. Fusco F. Gargano D. Gasparrini N. Giglietto P. Giommi F. Giordano M. Giroletti G. Godfrey D. Green I. A. Grenier S. Guiriec E. Hays D. Horan G. Iafrate T. Jogler G. Jóhannesson M. Kuss G. La Mura S. Larsson L. Latronico J. Li L. Li F. Longo F. Loparco B. Lott M. N. Lovellette P. Lubrano G. M. Madejski J. Magill S. Maldera A. Manfreda M. Mayer M. N. Mazziotta P. F. Michelson W. Mitthumsiri T. Mizuno A. A. Moiseev M. E. Monzani A. Morselli I. V. Moskalenko S. Murgia M. Negro E. Nuss T. Ohsugi C. Okada N. Omodei E. Orlando J. F. Ormes D. Paneque J. S. Perkins M. Pesce-Rollins V. Petrosian F. Piron G. Pivato T. A. Porter S. Rainò R. Rando M. Razzano S. Razzaque A. Reimer O. Reimer T. Reposeur R. W. Romani M. Sánchez-Conde J. Schmid A. Schulz C. Sgrò D. Simone E. J. Siskind F. Spada G. Spandre P. Spinelli D. J. Suson H. Takahashi J. B. Thayer L. Tibaldo D. F. Torres E. Troja G. Vianello M. Yassine S. Zimmer Deutsches Elektronen Synchrotron DESY D-15738 Zeuthen Germany Department of Physics and Astronomy Clemson University Kinard Lab of Physics Clemson SC 29634-0978 USA W. W. Hansen Experimental Physics Laboratory Kavli Institute for Particle Astrophysics and Cosmology Department of Physics and SLAC National Accelerator Laboratory Stanford University Stanford CA 94305 USA Santa Cruz Institute for Particle Physics Department of Physics and Department of Astronomy and Astrophysics University of California at Santa Cruz Santa Cruz CA 95064 USA Università di Pisa and Istituto Nazionale di Fisica Nucleare Sezione di Pisa I-56127 Pisa Italy Laboratoire AIM CEA-IRFU/CNRS/Université Paris Diderot Service d’Astrophysique CEA Saclay F-91191 Gif sur Yvette France Istituto Nazionale di Fisica Nucleare Sezione di Trieste I-34127 Trieste Italy Dipartimento di Fisica Università di Trieste I-34127 Trieste Italy Istituto Nazionale di Fisica Nucleare Sezione di Padova I-35131 Padova Italy Dipartimento di Fisica e Astronomia “G. Galilei” Università di Padova I-35131 Padova Italy Dept. of Physics and Wisconsin IceCube Particle Astrophysics Center University of Wisconsin Madison WI 53706 USA Istituto Nazionale di Fisica Nucleare Sezione di Pisa I-56127 Pisa Italy Istituto Nazionale di Fisica Nucleare Sezione di Bari I-70126 Bari Italy Istituto Nazionale di Fisica Nucleare Sezione di Torino I-10125 Torino Italy Dipartimento di Fisica Generale “Amadeo Avogadro” Università degli Studi di Torino I-10125 Torino Italy Laboratoire Univers et Particules de Montpellier Université Montpellier CNRS/IN2P3 Montpellier France Department of Physics University of Johannesburg PO Box 524 Auckland Park 2006 South Africa Laboratoire Leprince-Ringuet École polytechnique CNRS/IN2P3 Palaiseau France Consorzio Interuniversitario per la Fisica Spaziale (CIFS) I-10133 Torino Italy Dipartimento di Fisica “M. Merlin” dell’Università e del Politecnico di Bari I-70126 Bari Italy INAF-Istituto di As

The Fermi Large Area Telescope (LAT) Collaboration has recently released a catalog of 360 sources detected above 50 GeV (2FHL). This catalog was obtained using 80 months of data re-processed with Pass 8, the newest event-level analysis, which significantly improves the acceptance and angular resolution of the instrument. Most of the 2FHL sources at high Galactic latitude are blazars. Using detailed Monte Carlo simulations, we measure, for the first time, the source count distribution, dN/dS, of extragalactic γ-ray sources at E>50 GeV and find that it is compatible with a Euclidean distribution down to the lowest measured source flux in the 2FHL (∼8×10−12 ph cm−2 s−1). We employ a one-point photon fluctuation analysis to constrain the behavior of dN/dS below the source detection threshold. Overall, the source count distribution is constrained over three decades in flux and found compatible with a broken power law with a break flux, Sb, in the range [8×10−12,1.5×10−11] ph cm−2 s−1 and power-law indices below and above the break of α2∈[1.60,1.75] and α1=2.49±0.12, respectively. Integration of dN/dS shows that point sources account for at least 86−14+16% of the total extragalactic γ-ray background. The simple form of the derived source count distribution is consistent with a single population (i.e., blazars) dominating the source counts to the minimum flux explored by this analysis. We estimate the density of sources detectable in blind surveys that will be performed in the coming years by the Cherenkov Telescope Array.

关键词： Gamma ray astronomy Galactic nuclei & quasars

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On authentication in a connected vehicle: Secure integration of mobile devices with vehicular networks

On authentication in a connected vehicle: Secure integration...

引用

2013 ACM/IEEE International Conference on Cyber-Physical Systems, ICCPS 2013

作者： Han, Kyusuk Divya Potluri, Swapna Shin, Kang G. Real-Time Computing Laboratory Department of Electrical Engineering and Computer Science University of Michigan Ann Arbor M148109-2121 United States

ISBN: (纸本)9781450319966

Recent advances in in-vehicle technologies have paved way to a new era of connectivity. Vehicle manufacturers have already deployed various technologies for driving assistance, anti-theft, and infotainment. They are now developing ways to interface mobile devices with vehicles and provide the customer's smart phone or tablet the ability to send/receive information to/from the car. However, such an integration introduces severe security risks to the vehicle. The in-vehicle network was originally designed to operate in a closed environment and thus, security was not of concern. It has now become an important issue due to an increasing number of external interfaces to the in-vehicle network. Several studies have already shown that an in-vehicle network can be easily compromised just by connecting cheap commercial devices and doing reverse engineering. Although research efforts have been made to secure in-vehicle networks, most of them focused on defining security requirements, or presenting attack scenarios without providing any feasible solution. Also, to the best of our knowledge, there hasn't been any study with a specific focus on understanding and analyzing the security aspects of integrating mobile devices with cars. In this paper, we define the integration model, present the attack scenarios, define the security objectives, and then propose a 3-step verification mechanism that meets our objectives. © 2013 IEEE.

关键词： Authentication

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Measurement of the high-energy gamma-ray emission from the Moon with the Fermi Large Area Telescope

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Physical Review D 2016年第8期93卷 082001-082001页

作者： M. Ackermann M. Ajello A. Albert W. B. Atwood L. Baldini G. Barbiellini D. Bastieri R. Bellazzini E. Bissaldi R. D. Blandford R. Bonino E. Bottacini J. Bregeon P. Bruel R. Buehler G. A. Caliandro R. A. Cameron M. Caragiulo P. A. Caraveo E. Cavazzuti C. Cecchi A. Chekhtman J. Chiang G. Chiaro S. Ciprini R. Claus J. Cohen-Tanugi F. Costanza A. Cuoco S. Cutini F. D’Ammando A. de Angelis F. de Palma R. Desiante S. W. Digel L. Di Venere P. S. Drell C. Favuzzi S. J. Fegan W. B. Focke A. Franckowiak S. Funk P. Fusco F. Gargano D. Gasparrini N. Giglietto F. Giordano M. Giroletti T. Glanzman G. Godfrey I. A. Grenier J. E. Grove S. Guiriec A. K. Harding J. W. Hewitt D. Horan X. Hou G. Iafrate G. Jóhannesson T. Kamae M. Kuss S. Larsson L. Latronico J. Li L. Li F. Longo F. Loparco M. N. Lovellette P. Lubrano J. Magill S. Maldera A. Manfreda M. Mayer M. N. Mazziotta P. F. Michelson W. Mitthumsiri T. Mizuno M. E. Monzani A. Morselli S. Murgia E. Nuss N. Omodei E. Orlando J. F. Ormes D. Paneque J. S. Perkins M. Pesce-Rollins V. Petrosian F. Piron G. Pivato S. Rainò R. Rando M. Razzano A. Reimer O. Reimer T. Reposeur C. Sgrò E. J. Siskind F. Spada G. Spandre P. Spinelli H. Takahashi J. B. Thayer D. J. Thompson L. Tibaldo D. F. Torres G. Tosti E. Troja G. Vianello B. L. Winer K. S. Wood M. Yassine F. Cerutti A. Ferrari P. R. Sala Deutsches Elektronen Synchrotron DESY D-15738 Zeuthen Germany Department of Physics and Astronomy Clemson University Kinard Lab of Physics Clemson South Carolina 29634-0978 USA W. W. Hansen Experimental Physics Laboratory Kavli Institute for Particle Astrophysics and Cosmology Department of Physics and SLAC National Accelerator Laboratory Stanford University Stanford California 94305 USA Santa Cruz Institute for Particle Physics Department of Physics and Department of Astronomy and Astrophysics University of California at Santa Cruz Santa Cruz California 95064 USA Università di Pisa and Istituto Nazionale di Fisica Nucleare Sezione di Pisa I-56127 Pisa Italy Istituto Nazionale di Fisica Nucleare Sezione di Trieste I-34127 Trieste Italy Dipartimento di Fisica Università di Trieste I-34127 Trieste Italy Istituto Nazionale di Fisica Nucleare Sezione di Padova I-35131 Padova Italy Dipartimento di Fisica e Astronomia “G. Galilei” Università di Padova I-35131 Padova Italy Istituto Nazionale di Fisica Nucleare Sezione di Pisa I-56127 Pisa Italy Istituto Nazionale di Fisica Nucleare Sezione di Bari I-70126 Bari Italy Istituto Nazionale di Fisica Nucleare Sezione di Torino I-10125 Torino Italy Dipartimento di Fisica Generale “Amadeo Avogadro” Università degli Studi di Torino I-10125 Torino Italy Laboratoire Univers et Particules de Montpellier Université Montpellier CNRS/IN2P3 F-34095 Montpellier France Laboratoire Leprince-Ringuet École polytechnique CNRS/IN2P3 F-91128 Palaiseau Cedex France Consorzio Interuniversitario per la Fisica Spaziale (CIFS) I-10133 Torino Italy Dipartimento di Fisica “M. Merlin” dell’Università e del Politecnico di Bari I-70126 Bari Italy INAF-Istituto di Astrofisica Spaziale e Fisica Cosmica I-20133 Milano Italy Agenzia Spaziale Italiana (ASI) Science Data Center I-00133 Roma Italy Istituto Nazionale di Fisica Nucleare Sezione di Perugia I-06123 Perugia Italy Dipartimento di Fisica Università degli Studi di Perugia I-06123 Perugia

We have measured the gamma-ray emission spectrum of the Moon using the data collected by the Large Area Telescope onboard the Fermi satellite during its first seven years of operation, in the energy range from 30 MeV up to a few GeV. We have also studied the time evolution of the flux, finding a correlation with the solar activity. We have developed a full Monte Carlo simulation describing the interactions of cosmic rays with the lunar surface. The results of the present analysis can be explained in the framework of this model, where the production of gamma rays is due to the interactions of cosmic-ray proton and helium nuclei with the surface of the Moon. Finally, we have used our simulation to derive the cosmic-ray proton and helium spectra near Earth from the Moon gamma-ray data.

关键词： Cosmic ray sources Cosmic rays & astroparticles Gamma ray astronomy Solar cycles

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