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Comparison of Polarized Radiative Transfer Codes Used by the EHT Collaboration

The Astrophysical Journal 2023年第1期950卷 35-35页

作者： Ben S. Prather Jason Dexter Monika Moscibrodzka Hung-Yi Pu Thomas Bronzwaer Jordy Davelaar Ziri Younsi Charles F. Gammie Roman Gold George N. Wong Kazunori Akiyama Antxon Alberdi Walter Alef Juan Carlos Algaba Richard Anantua Keiichi Asada Rebecca Azulay Uwe Bach Anne-Kathrin Baczko David Ball Mislav Baloković John Barrett Michi Bauböck Bradford A. Benson Dan Bintley Lindy Blackburn Raymond Blundell Katherine L. Bouman Geoffrey C. Bower Hope Boyce Michael Bremer Christiaan D. Brinkerink Roger Brissenden Silke Britzen Avery E. Broderick Dominique Broguiere Sandra Bustamante Do-Young Byun John E. Carlstrom Chiara Ceccobello Andrew Chael Chi-kwan Chan Dominic O. Chang Koushik Chatterjee Shami Chatterjee Ming-Tang Chen Yongjun Chen Xiaopeng Cheng Ilje Cho Pierre Christian Nicholas S. Conroy John E. Conway James M. Cordes Thomas M. Crawford Geoffrey B. Crew Alejandro Cruz-Osorio Yuzhu Cui Mariafelicia De Laurentis Roger Deane Jessica Dempsey Gregory Desvignes Vedant Dhruv Sheperd S. Doeleman Sean Dougal Sergio A. Dzib Ralph P. Eatough Razieh Emami Heino Falcke Joseph Farah Vincent L. Fish Ed Fomalont H. Alyson Ford Raquel Fraga-Encinas William T. Freeman Per Friberg Christian M. Fromm Antonio Fuentes Peter Galison Roberto García Olivier Gentaz Boris Georgiev Ciriaco Goddi Arturo I. Gómez-Ruiz José L. Gómez Minfeng Gu Mark Gurwell Kazuhiro Hada Daryl Haggard Kari Haworth Michael H. Hecht Ronald Hesper Dirk Heumann Luis C. Ho Paul Ho Mareki Honma Chih-Wei L. Huang Lei Huang David H. Hughes Shiro Ikeda C. M. Violette Impellizzeri Makoto Inoue Sara Issaoun David J. James Buell T. Jannuzi Michael Janssen Britton Jeter Wu Jiang Alejandra Jiménez-Rosales Michael D. Johnson Svetlana Jorstad Abhishek V. Joshi Taehyun Jung Mansour Karami Ramesh Karuppusamy Tomohisa Kawashima Garrett K. Keating Mark Kettenis Dong-Jin Kim Jae-Young Kim Jongsoo Kim Junhan Kim Motoki Kino Jun Yi Koay Prashant Kocherlakota Yutaro Kofuji Shoko Koyama Carsten Kramer Michael Kramer Thomas P. Krichbaum Cheng-Yu Kuo Noemi La Bella Tod R. Lauer Daeyoung L CCS-2 Los Alamos National Laboratory P.O. Box 1663 Los Alamos NM 87545 USA bprather@lanl.gov JILA and Department of Astrophysical and Planetary Sciences University of Colorado Boulder CO 80309 USA Department of Astrophysics/IMAPP Radboud University P.O. Box 9010 6500 GL Nijmegen The Netherlands Department of Physics National Taiwan Normal University No. 88 Sec.4 Tingzhou Road Taipei 116 Taiwan R.O.C. Center of Astronomy and Gravitation National Taiwan Normal University No. 88 Sec. 4 Tingzhou Road Taipei 116 Taiwan R.O.C. Institute of Astronomy and Astrophysics Academia Sinica 11F of Astronomy-Mathematics Building AS/NTU No. 1 Sec. 4 Roosevelt Road Taipei 10617 Taiwan R.O.C. Department of Astronomy and Columbia Astrophysics Laboratory Columbia University 550 W. 120th Street New York NY 10027 USA Center for Computational Astrophysics Flatiron Institute 162 Fifth Avenue New York NY 10010 USA Department of Astrophysics Institute for Mathematics Astrophysics and Particle Physics (IMAPP) Radboud University P.O. Box 9010 6500 GL Nijmegen The Netherlands Mullard Space Science Laboratory University College London Holmbury St. Mary Dorking Surrey RH5 6NT UK Institut für Theoretische Physik Goethe-Universität Frankfurt Max-von-Laue-Straße 1 D-60438 Frankfurt am Main Germany Department of Physics University of Illinois 1110 West Green Street Urbana IL 61801 USA Department of Astronomy University of Illinois at Urbana-Champaign 1002 West Green Street Urbana IL 61801 USA NCSA University of Illinois 1205 W. Clark Street Urbana IL 61801 USA CP3-Origins University of Southern Denmark Campusvej 55 DK-5230 Odense M Denmark School of Natural Sciences Institute for Advanced Study 1 Einstein Drive Princeton NJ 08540 USA Princeton Gravity Initiative Princeton University Princeton NJ 08544 USA Massachusetts Institute of Technology Haystack Observatory 99 Millstone Road Westford MA 01886 USA National Astronomical Observatory of Japan 2-21-1 Osaw

Interpretation of resolved polarized images of black holes by the Event Horizon Telescope (EHT) requires predictions of the polarized emission observable by an Earth-based instrument for a particular model of the black hole accretion system. Such predictions are generated by general relativistic radiative transfer (GRRT) codes, which integrate the equations of polarized radiative transfer in curved spacetime. A selection of ray-tracing GRRT codes used within the EHT Collaboration is evaluated for accuracy and consistency in producing a selection of test images, demonstrating that the various methods and implementations of radiative transfer calculations are highly consistent. When imaging an analytic accretion model, we find that all codes produce images similar within a pixel-wise normalized mean squared error (NMSE) of 0.012 in the worst case. When imaging a snapshot from a cell-based magnetohydrodynamic simulation, we find all test images to be similar within NMSEs of 0.02, 0.04, 0.04, and 0.12 in Stokes I, Q, U, and V, respectively. We additionally find the values of several image metrics relevant to published EHT results to be in agreement to much better precision than measurement uncertainties.

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Texture segmentation using active contour model incorporated with edge flow on MRI image

Texture segmentation using active contour model incorporated...

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IEEE Region 10 International Conference TENCON

作者： Tanunchai Boonnuk Thanwa Sripramong Sanun Srisuk The Electrical Engineering Graduate Program Mahanakorn University of Technology Bangkok Thailand Faculty of Industrial Technology Nakhon Phanom University Nakhon Phanom Thailand

ISBN: (纸本)9781479940745

This paper are presented novel method of texture segmentation using active contour model incorporated with edge flow. The edge flow magnitude was used as a main force (external force) of active contour model. The texture segmentation from both active contour model with edge flow and traditional active contour model were compared. The results reveal that the active contour models with edge flow shown better quality of texture segmentation. In contrast with traditional method, it was not able to identify edge and texture of image. We also found that it works well in the MRI image segmentation and Ultrasound image segmentation.

关键词： Image edge detection Active contours Image segmentation Vectors Equations Mathematical model Force

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Analysis of BitTorrent inspired by The Application Layer Traffic Optimization

Analysis of BitTorrent inspired by The Application Layer Tra...

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International Conference on Information Networking

作者： Nattee Pinthong Woraphon Lilakiatsakun The Electrical Engineering Graduate Program Mahanakorn University of Technology Bangkok Thailand Faculty of Information Science and Technology Mahanakorn University of Technology Bangkok Thailand

This paper present an Analysis of BitTorrent inspired by The Application Layer Traffic Optimization. Recent studies suggest that the long-term relationships among BitTorrent peers can be explored to enhance the downloading performance. In such systems, The mechanisms like tit-for-tat, optimistic unchoking, anti-snubbing and various piece and selection strategy have been working very well. This work is an attempt to study the analysis of BitTorrent protocol and its networking infrastructure through two strategies, (A) we propose a novel approach to make BitTorrent node aware of the topology of underlying networks. Then we modify BitTorrent's original algorithms and replace them with new localized algorithms based on autonomous system (AS) hops. (B) we conduct comprehensive experiments to verify the correctness and effectiveness of our scheme based on the PeerSim simulation. The simulation result shows that, with our scheme, nodes in BitTorrent-like systems have better sense of the topology of their underlying networks, and can interact more efficiently. Besides, our scheme can help to decrease the traffic, optimize traffic distribution across the whole networks, and obtained are used to infer various performance parameters of BitTorrent protocols.

关键词： Peer-to-peer computing Topology Network topology Protocols Algorithm design and analysis IP networks Optimization

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The implementation of the full bridge inverter for the series resonant load

The implementation of the full bridge inverter for the serie...

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International Conference on electrical engineering/Electronics, Computer, Telecommunications and Information Technology, ECTI-CON

作者： Jirapong Jittakort Samart Yachiangkam Sayan Kleangsin Faculty of Technical Education Rajamangala University of Technology Thanyaburi Pathumthani Thailand Department of Electrical Engineering Rajamangala University of Technology Lanna Chiang Mai Chiang Mai Thailand Physics and Engineering Program Department of Science Service Bangkok Thailand

This paper presents the prototype of the series resonant inverter as the full-bridge inverter with the series resonant load as the induction cooking load for the electrical education laboratory of the faculty education of the RMUTT. The inverter is controlled by the microcontroller (MCU) as dsPIC30F2010 that it is three schemes of the gate-signal such as the vary frequency modulation (VFM), the asymmetrical duty cycle (ADC), and an asymmetrical voltage cancellation (AVC) schemes that all technique is to achieve the zero-voltage switching (ZVS) condition. The theory of three schemes can be confirmed by the experimental results.

关键词： Inverters Bridge circuits Logic gates Insulated gate bipolar transistors Automatic voltage control Education

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Adaptive neural networks for nonlinear dynamic systems identification

Adaptive neural networks for nonlinear dynamic systems ident...

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2013 5th International Conference on Computational Intelligence, Modelling and Simulation, CIMSim 2013

作者： Sitompul, Erwin Study Program Electrical Engineering Faculty of Engineering President University Bekasi Indonesia

ISBN: (纸本)9780769551555

A new scheme for adaptive neural networks for nonlinear dynamic system identification is proposed in this paper. The network of structure multi-layer perceptron with external recurrence is trained offline at first to get the initial network parameters. The parameters of the network are classified into short-term memory part and long-term memory part. The short-term memory part includes the parameters which are linear to the network output. In the implementation, the network is validated in each sampling time using a set of new measurement data. Training procedure will be executed if the model error exceeds a specified value and the short-term memory part will be adjusted. The application in modelling of room thermal behaviour demonstrates the performance of the proposed scheme. © 2013 IEEE.

关键词： Nonlinear dynamical systems

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Blind and lighting control to maintain comfort light intensity of the classroom utilizing Microcontroller ATmega8535

Blind and lighting control to maintain comfort light intensi...

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2013 5th International Conference on Information Technology and electrical engineering, ICITEE 2013

作者： Silitonga, Arthur Indrawan, I Gusti L. W. Study Program of Electrical Engineering Faculty of Engineering President University Bekasi Indonesia

ISBN: (纸本)9781479904259

A stable light intensity level of a classroom can actually be obtained by integrating automatic lamp brightness controller with automatic blind system. A brightness controller of the lamp, especially incandescent type can be developed by adopting the principle of phase firing angle. It should be implemented in such a way so that the firing angle is set precisely to keep the classroom's light intensity stays in a steady level. Next, the opening and closing process of the blind can also be done using stepper motor which will be controlled automatically by a microcontroller through a hardware driver. This is intended to take the advantage of light contribution from the outside instead of directly switching on or brightening the lamp. © 2013 IEEE.

关键词： Controllers

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Vulnerability and economic considerations in designing network topology

Vulnerability and economic considerations in designing netwo...

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2013 13th International Conference on Quality in Research, QiR 2013 - In Conjunction with the 2nd International Conference on Civic Space, ICCS 2013

作者： Suhartomo, Antonius Study Program of Electrical Engineering Faculty of Engineering President Univeristy Kota Jababeka Bekasi 17550 Indonesia

ISBN: (纸本)9781467357852

Technological developments change the way of life of all people in interacting with each other, regardless of distance and time. One such interaction is the activity of the exchange of information through communication networks, which are either one-way or two-way with a variety of information, such as voices, images, and data, with the desire to have a fast and reliable delivery. If G(V, E) represents a graph or a network with a number of nodes, V = n, and the number of links, E = e, then assume the nodes are reliable and the links can fail. We investigate new parameter of connectivity called 'k-component order edge-connectivity' or 'component order edge-connectivity', denoted by λ (k)c, in which within each type of topology is then compared such as in the topology of path, cycle, star, complete, and wheel networks, then choose the best selection in vulnerability and economic point of views. © 2013 IEEE.

关键词： Network security

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Optimizing the Energy Portfolio of the Mexican Electricity Sector by 2050 Considering CO 2 eq Emissions and Life Cycle Assessment

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Energy Procedia 2014年 57卷 850-859页

作者： Edgar Roberto Sandoval García Arturo Morales-Acevedo PhD Program on Science Technology & Society CINVESTAV- IPN Av. Inst. Pol. Nacional No. 2508 07360 Mexico D. F. Mexico Electrical Engineering Departmnet CINVESTAV- IPN Av. Inst. Pol. Nacional No. 2508 07360 Mexico D. F. Mexico

Today, Mexico is one of the leading countries of the Latin American region in receiving foreign direct investment, with expected GDP growth for the coming years between 4% and 6% per annum, according to estimates published by the OECD and other international organizations. Sustaining such growth demands the strengthening of one of the main pillars of economic development, the National Electricity Sector. To accomplish this growth in the electricity sector will require an energy portfolio that allows for three basic conditions in the sector's planning: reliability, economy and sustainability. To ensure the sustainability of the National Electric Sector, the optimal energy portfolio must meet the CO 2 eq emission reduction that the country has adopted based on international commitments. Sources of electricity generation with low water consumption as well as reduced pollutant discharge are needed, given the great importance of water efficiency in energy production. This paper determines an optimal energy portfolio involving conventional technologies, clean technologies and alternative and intermittent renewable technologies, based on a simple optimization model and using variables such as future electricity demand, CO 2 eq emissions by source, and taking into account data from several studies of life cycle assessment of the electricity sector, such as energy payback rate and water pollution. The research presented assumes two scenarios of growth in electricity demand of about 350 and 1,150 TW-hours in 2050.

关键词： energy portfolio optimization mexican electricity sector life cycle assessment GHG emissions.

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Ultra wideband microstrip antenna using T-shaped stub fed by coplanar waveguide

Ultra wideband microstrip antenna using T-shaped stub fed by...

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2013 13th International Conference on Quality in Research, QiR 2013 - In Conjunction with the 2nd International Conference on Civic Space, ICCS 2013

作者： Hadinegoro, Rastanto Surjati, Indra Ningsih, Yuli Kurnia Graduate Program Department of Electrical Engineering Faculty of Industrial Technology TrisaktiUniversity Jakarta Indonesia

ISBN: (纸本)9781467357852

A novel design for ultra wideband microstrip antenna using T-shape stub fed by coplanar waveguide is proposed and experimentally studied. The multiband frequencies can be reached by controlling the length of a and b of the T shaped stub. The results shown that the proposed antenna can be achieved multiband frequencies with return loss -21.5 dB at frequency 2.65GHz, return loss -24.5dB at frequency 5GHz, and return loss -35dB at frequency 8.42GHz. Impedance bandwidth of the proposed antenna is 6570 MHz or about 200% (VSWR

关键词： Coplanar waveguides

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The γ-ray spectrum of the core of Centaurus A as observed with H.E.S.S. and Fermi-LAT

arXiv

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arXiv 2018年

作者： Abdalla, H. Abramowski, A. Aharonian, F. Benkhali, F. Ait Angüner, E.O. Arakawa, M. Armand, C. Arrieta, M. Backes, M. Balzer, A. Barnard, M. Becherini, Y. Tjus, J. Becker Berge, D. Bernhard, S. Bernlöhr, K. Blackwell, R. Böttcher, M. Boisson, C. Bolmont, J. Bonnefoy, S. Bordas, P. Bregeon, J. Brun, F. Brun, P. Bryan, M. Büchele, M. Bulik, T. Capasso, M. Caroff, S. Carosi, A. Casanova, S. Cerruti, M. Chakraborty, N. Chaves, R.C.G. Chen, A. Chevalier, J. Colafrancesco, S. Condon, B. Conrad, J. Davids, I.D. Decock, J. Deil, C. Devin, J. deWilt, P. Dirson, L. Djannati-Ataï, A. Donath, A. O’C. Drury, L. Dyks, J. Edwards, T. Egberts, K. Emery, G. Ernenwein, J.-P. Eschbach, S. Farnier, C. Fegan, S. Fernandes, M.V. Fiasson, A. Fontaine, G. Funk, S. Füßling, M. Gabici, S. Gallant, Y.A. Garrigoux, T. Gaté, F. Giavitto, G. Glawion, D. Glicenstein, J.F. Gottschall, D. Grondin, M.-H. Hahn, J. Haupt, M. Hawkes, J. Heinzelmann, G. Henri, G. Hermann, G. Hinton, J.A. Hofmann, W. Hoischen, C. Holch, T.L. Holler, M. Horns, D. Ivascenko, A. Iwasaki, H. Jacholkowska, A. Jamrozy, M. Jankowsky, D. Jankowsky, F. Jingo, M. Jouvin, L. Jung-Richardt, I. Kastendieck, M.A. Katarzyński, K. Katsuragawa, M. Katz, U. Kerszberg, D. Khangulyan, D. Khélifi, B. King, J. Klepser, S. Klochkov, D. Kluźniak, W. Komin, Nu. Kosack, K. Krakau, S. Kraus, M. Krüger, P.P. Laffon, H. Lamanna, G. Lau, J. Lefaucheur, J. Lemière, A. Lemoine-Goumard, M. Lenain, J.-P. Leser, E. Lohse, T. Lorentz, M. Liu, R. López-Coto, R. Lypova, I. Malyshev, D. Marandon, V. Marcowith, A. Mariaud, C. Marx, R. Maurin, G. Maxted, N. Mayer, M. Meintjes, P.J. Meyer, M. Mitchell, A.M.W. Moderski, R. Mohamed, M. Mohrmann, L. Morå, K. Moulin, E. Murach, T. Nakashima, S. de Naurois, M. Ndiyavala, H. Niederwanger, F. Niemiec, J. Oakes, L. O’Brien, P. Odaka, H. Ohm, S. Ostrowski, M. Oya, I. Padovani, M. Panter, M. Parsons, R.D. Pekeur, N.W. Pelletier, G. Perennes, C. Petrucci, P.-O. Centre for Space Research North-West University Potchefstroom2520 South Africa Universität Hamburg Institut für Experimentalphysik Luruper Chaussee 149 HamburgD 22761 Germany Max-Planck-Institut für Kernphysik P.O. Box 103980 HeidelbergD 69029 Germany Dublin Institute for Advanced Studies 31 Fitzwilliam Place Dublin 2 Ireland National Academy of Sciences of the Republic of Armenia Marshall Baghramian Avenue 24 Yerevan0019 Armenia Instytut Fizyki JĄdrowej PAN ul. Radzikowskiego 152 Kraków31-342 Poland Department of Physics Rikkyo University 3-34-1 Nishi-Ikebukuro Toshima-ku Tokyo171-8501 Japan Laboratoire d’Annecy de Physique des Particules Université Savoie Mont-Blanc CNRS/IN2P3 Annecy-le-VieuxF-74941 France LUTH Observatoire de Paris PSL Research University CNRS Université Paris Diderot 5 Place Jules Janssen Meudon92190 France University of Namibia Department of Physics Private Bag 13301 Windhoek Namibia GRAPPA Anton Pannekoek Institute for Astronomy University of Amsterdam Science Park 904 Amsterdam1098 XH Netherlands Department of Physics and Electrical Engineering Linnaeus University Växjö351 95 Sweden Institut für Theoretische Physik Lehrstuhl IV: Weltraum und Astrophysik Ruhr-Universität Bochum BochumD 44780 Germany DESY ZeuthenD-15738 Germany Institut für Astro- und Teilchenphysik Leopold-Franzens-Universität Innsbruck InnsbruckA-6020 Austria School of Physical Sciences University of Adelaide Adelaide5005 Australia 4 place Jussieu Paris Cedex 5F-75252 France Laboratoire Univers et Particules de Montpellier Université Montpellier CNRS/IN2P3 CC 72 Place Eugène Bataillon Montpellier Cedex 5F-34095 France Université Bordeaux CNRS/IN2P3 Centre d’Études Nucléaires de Bordeaux Gradignan Gradignan33175 France IRFU CEA Université Paris-Saclay Gif-sur-YvetteF-91191 France Friedrich-Alexander-Universität Erlangen-Nürnberg Erlangen Centre for Astroparticle Physics Erwin-Rommel-Str. 1 ErlangenD 91058 Germany Astronomica

Centaurus A (Cen A) is the nearest radio galaxy discovered as a very-high-energy (VHE;100 GeV-100 TeV) γ-ray source by the High Energy Stereoscopic System (H.E.S.S.). It is a faint VHE γ-ray emitter, though its VHE flux exceeds both the extrapolation from early Fermi-LAT observations as well as expectations from a (misaligned) single-zone synchrotron-self Compton (SSC) description. The latter satisfactorily reproduces the emission from Cen A at lower energies up to a few GeV. New observations with H.E.S.S., comparable in exposure time to those previously reported, were performed and eight years of Fermi-LAT data were accumulated to clarify the spectral characteristics of the γ-ray emission from the core of Cen A. The results allow us for the first time to achieve the goal of constructing a representative, contemporaneous γ-ray core spectrum of Cen A over almost five orders of magnitude in energy. Advanced analysis methods, including the template fitting method, allow detection in the VHE range of the core with a statistical significance of 12σ on the basis of 213 hours of total exposure time. The spectrum in the energy range of 250 GeV-6 TeV is compatible with a power-law function with a photon index Γ = 2.52 ± 0.13stat ± 0.20sys. An updated Fermi-LAT analysis provides evidence for spectral hardening by ∆Γ 0.4 ± 0.1 at γ-ray energies above 2.8+1.0−0.6 GeV at a level of 4.0σ. The fact that the spectrum hardens at GeV energies and extends into the VHE regime disfavour a single-zone SSC interpretation for the overall spectral energy distribution (SED) of the core and is suggestive of a new γ-ray emitting component connecting the high-energy emission above the break energy to the one observed at VHE energies. The absence of significant variability at both GeV and TeV energies does not yet allow disentanglement of the physical 1 nature of this component, though a jet-related origin is possible and a simple two-zone SED model fit is provided to this end. Copyright © 2018,

关键词： Gamma rays

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