797 research outputs found

    Determining parameters of ULXs with model grids of extended atmospheres

    Full text link
    In current work we continued study of wind parameters of ultraluminous X-ray sources (ULXs) using model grids of extended atmospheres. We present sets of models with temperatures from 18000 up to 56000K as a line equivalent widths (EWs) and their ratios diagrams. The fundamental wind parameters for some spectrally studied ULXs were estimated using EW diagrams. Also, influence of the wind velocity law on the equivalent widths of observed emission lines was investigated. This study was funded by RFBR according to the research project 18-32-20214.Comment: "Groundbased Astronomy in Russia. XXI Century" conference proceeding

    IRIS: A new generation of IRAS maps

    Full text link
    The Infrared Astronomical Satellite (IRAS) had a tremendous impact on many areas of modern astrophysics. In particular it revealed the ubiquity of infrared cirrus that are a spectacular manifestation of the interstellar medium complexity but also an important foreground for observational cosmology. With the forthcoming Planck satellite there is a need for all-sky complementary data sets with arcminute resolution that can bring informations on specific foreground emissions that contaminate the Cosmic Microwave Background radiation. With its 4 arcmin resolution matching perfectly the high-frequency bands of Planck, IRAS is a natural data set to study the variations of dust properties at all scales. But the latest version of the images delivered by the IRAS team (the ISSA plates) suffer from calibration, zero level and striping problems that can preclude its use, especially at 12 and 25 micron. In this paper we present how we proceeded to solve each of these problems and enhance significantly the general quality of the ISSA plates in the four bands (12, 25, 60 and 100 micron). This new generation of IRAS images, called IRIS, benefits from a better zodiacal light subtraction, from a calibration and zero level compatible with DIRBE, and from a better destriping. At 100 micron the IRIS product is also a significant improvement from the Schlegel et al. (1998) maps. IRIS keeps the full ISSA resolution, it includes well calibrated point sources and the diffuse emission calibration at scales smaller than 1 degree was corrected for the variation of the IRAS detector responsivity with scale and brightness. The uncertainty on the IRIS calibration and zero level are dominated by the uncertainty on the DIRBE calibration and on the accuracy of the zodiacal light model.Comment: 16 pages, 17 figures, accepted for publication in ApJ (Suppl). Higher resolution version available at http://www.cita.utoronto.ca/~mamd/IRIS/IrisTechnical.htm

    Trans-Eurasian Land Transport Corridors: Assessment of Prospects and Barriers

    Get PDF
    This study is part of the “Challenges and Opportunities of Economic Integration within a Wider European and Eurasian Space” project, an ambitious undertaking seeking to scope the complex issues and potentials for economic cooperation between the European Union (EU) and the Eurasian Economic Union (EAEU), as well as with third-party countries of the vast Eurasian landmass. It is based on the intense research going on in over 25 countries, including Member-States of both the EU and the EAEU, the United States, China, Japan, Turkey and Ukraine, and on the results of seven international project workshops held at IIASA from June 2013 to April 2016, which discussed and synthesized these analyses. The project workshops were attended by renowned academics and high-level policymakers, including representatives from the European Commission and the Eurasian Economic Commission. This report presents the synthesis of three years of multi-disciplinary work

    Cross-relaxation and phonon bottleneck effects on magnetization dynamics in LiYF4:Ho3+

    Full text link
    Frequency and dc magnetic field dependences of dynamic susceptibility in diluted paramagnets LiYF4_4:Ho3+^{3+} have been measured at liquid helium temperatures in the ac and dc magnetic fields parallel to the symmetry axis of a tetragonal crystal lattice. Experimental data are analyzed in the framework of microscopic theory of relaxation rates in the manifold of 24 electron-nuclear sublevels of the lowest non-Kramers doublet and the first excited singlet in the Ho3+^{3+} ground multiplet 5I8^5I_8 split by the crystal field of S4_4 symmetry. The one-phonon transition probabilities were computed using electron-phonon coupling constants calculated in the framework of exchange charge model and were checked by optical piezospectroscopic measurements. The specific features observed in field dependences of the in- and out-of-phase susceptibilities (humps and dips, respectively) at the crossings (anti-crossings) of the electron-nuclear sublevels are well reproduced by simulations when the phonon bottleneck effect and the cross-spin relaxation are taken into account

    Electrical load forecasting

    Full text link
    Some long-term design activities are based on electrical load forecasting. Forecasting errors result in the wrong decisions being made in the future. At present there are three widely used methods of forecasting: the method based on enlarged specific indexes (ESI), the econometric method and the self-sufficient method. All of these methods have their own disadvantages and errors in estimation. The main reasons for errors in areas such as objective reasoning, changes in production technology, the lack of reliable long-term forecasting for economy development and consumer infraction of load schedule are determined in this paper and an objective estimation for the forecasted error of different spheres of application is made. This work aims to determine a sphere of application for each of these methods and to develop a principal of combined application, so that they may decrease forecasting error. The purpose of this work consists of the creation of an electrical load forecasting method to obtain more reliable data for the different time periods and territory. A new method is presented, based on calculations carried out. Recommendations for all existing methods are given with reference to the calculations and the way that the combined application of several methods was introduced to increase the reliability of a forecast. © 2014 WIT Press.International Journal of Safety and Security Engineering;International Journal of Sustainable Development and Planning;WIT Transactions on Ecology and the Environmen
    corecore