92,881 research outputs found

    Rankine-Hugoniot Relations in Relativistic Combustion Waves

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    As a foundational element describing relativistic reacting waves of relevance to astrophysical phenomena, the Rankine-Hugoniot relations classifying the various propagation modes of detonation and deflagration are analyzed in the relativistic regime, with the results properly degenerating to the non-relativistic and highlyrelativistic limits. The existence of negative-pressure downstream flows is noted for relativistic shocks, which could be of interest in the understanding of the nature of dark energy. Entropy analysis for relativistic shock waves are also performed for relativistic fluids with different equations of state (EoS), denoting the existence of rarefaction shocks in fluids with adiabatic index \Gamma < 1 in their EoS. The analysis further shows that weak detonations and strong deflagrations, which are rare phenomena in terrestrial environments, are expected to exist more commonly in astrophysical systems because of the various endothermic reactions present therein. Additional topics of relevance to astrophysical phenomena are also discussed.Comment: 34 pages, 9 figures, accepted for publication in Ap

    Magnetic reconnection detonation in supernova remnants

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    As a key process that refreshes the interstellar medium, the dynamics and radiative properties of the supernova remnant (SNR) expansion front not only reflect the physical environment of the old interstellar medium (ISM) surrounding the supernova, but they also provide information about the refreshed ISM. However the expansion dynamics of SNRs cannot be simply explained by the conventional law of spherical shock wave propagation; on the other hand, the high energy radiation requires an additional electron acceleration mechanism in the shock front beyond thermal collision. We consider herein the detonation wave description of the SNR expansion, in which magnetic reconnection follows the shock front and transfers the SNR magnetic field energy to both fluid thermal energy and particle kinetic energy. The structure of the magnetic reconnection detonation (MRD) is identified based on scaling analysis in this paper. By applying the MRD description of the SNR expansion shock to the example of the Crab Nebula, this paper shows that the MRD description can explain both the accelerative expansion of the nebula as well as the origin of the luminous expanding shell.Comment: Accepted for publication in Ap

    Detailed comparison of Milky Way models based on stellar population synthesis and SDSS star counts at the north Galactic pole

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    We test the ability of the TRILEGAL and Besancon models to reproduce the CMD of SDSS data at the north Galactic pole (NGP). We show that a Hess diagram analysis of colour-magnitude diagrams is much more powerful than luminosity functions (LFs) in determining the Milky Way structure. We derive a best-fitting TRILEGAL model to simulate the NGP field in the (g-r, g) CMD of SDSS filters via Hess diagrams. For the Besancon model, we simulate the LFs and Hess diagrams in all SDSS filters. We use a chi2 analysis and determine the median of the relative deviations in the Hess diagrams to quantify the quality of the fits by the TRILEGAL models and the Besancon model in comparison and compare this with the Just-Jahreiss model. The input isochrones in the colour-absolute magnitude diagrams of the thick disc and halo are tested via the observed fiducial isochrones of globular clusters (GCs). We find that the default parameter set lacking a thick disc component gives the best representation of the LF in TRILEGAL. The Hess diagram reveals that a metal-poor thick disc is needed. In the Hess diagram, the median relative deviation of the TRILEGAL model and the SDSS data amounts to 25 percent, whereas for the Just-Jahreiss model the deviation is only 5.6 percent. The isochrone analysis shows that the representation of the MS of (at least metal-poor) stellar populations in the SDSS system is reliable. In contrast, the RGBs fail to match the observed fiducial sequences of GCs. The Besancon model shows a similar median relative deviation of 26 percent in (g-r, g). In the u band, the deviations are larger. There are significant offsets between the isochrone set used in the Besancon model and the observed fiducial isochrones. In contrast to Hess diagrams, LFs are insensitive to the detailed structure of the Milky Way components due to the extended spatial distribution along the line of sight.Comment: 21 pages, 17 figures and 5 tables. Accepted by publication of A&

    Optimal Controlled Teleportation

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    We give the analytic expressions of maximal probabilities of successfully controlled teleportating an unknown qubit via every kind of tripartite states. Besides, another kind of localizable entanglement is also determined. Furthermore, we give the sufficient and necessary condition that a three-qubit state can be collapsed to an EPR pair by a measurement on one qubit, and characterize the three-qubit states that can be used as quantum channel for controlled teleporting a qubit of unknown information with unit probability and with unit fidelity.Comment: 4 page

    Innovation Institution and Spatial Transfer of Energy Industry: The Case of Jiangsu Province, China

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    This study aims to explore the effect of innovation institution on spatial transfer of energy industry in Jiangsu, China. We focus on the disparity of innovation and energy industry, and analyze the spatial transfer difference in different types of energy industry, rather than view energy industry as a whole. The study demonstrates the spatial change of energy industry at regional level and maps the spatial pattern at city level. The study chooses intellectual property rights (IPRs) protection intensity, authorization patents and local research and development (R&D) investment as the proxy of innovation. Using official data and employing panel fixed-effect model at city-industry level, we conclude (a) innovation abilities significantly influence the spatial transfer of energy industry in Jiangsu. Especially, due to the different time, IPRs protection, patent counts, and R&D investment have different effects on different regions in Jiangsu; (b) 2010 is an important turning point for energy industry development in Jiangsu, and after 2010, the energy industry begins to shift to the middle and northern Jiangsu, whereas the spatial pattern of energy industry in coastal cities is basically unchanged; (c) there is a great difference between the regions in Jiangsu Province, and industrial upgrading has not been achieved in northern Jiangsu
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