43 research outputs found

    Investigation of the new cataclysmic variable 1RXS J180834.7+101041

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    We present the results of our photometric and spectroscopic studies of the new eclipsing cataclysmic variable star 1RXS J180834.7+101041. Its spectrum exhibits double-peaked hydrogen and helium emission lines. The Doppler maps constructed from hydrogen lines show a nonuniform distribution of emission in the disk similar to that observed in IP Peg. This suggests that the object can be a cataclysmic variable with tidal density waves in the disk. We have determined the component masses (M_WD =0.8 \pm 0.22 M_sun and M_RD =0.14 \pm 0.02 M_sun) and the binary inclination (i =78 \pm 1.5 deg) based on well-known relations between parameters for cataclysmic variable stars. We have modeled the binary light curves and showed that the model of a disk with two spots is capable of explaining the main observed features of the light curves.Comment: 22 pages, 9 figures, 2 tables, published in Astronomy Letters, 2011, 37, 845-85

    Isospin-Violating Meson-Nucleon Vertices as an Alternate Mechanism of Charge-Symmetry Breaking

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    We compute isospin-violating meson-nucleon coupling constants and their consequent charge-symmetry-breaking nucleon-nucleon potentials. The couplings result from evaluating matrix elements of quark currents between nucleon states in a nonrelativistic constituent quark model; the isospin violations arise from the difference in the up and down constituent quark masses. We find, in particular, that isospin violation in the omega-meson--nucleon vertex dominates the class IV CSB potential obtained from these considerations. We evaluate the resulting spin-singlet--triplet mixing angles, the quantities germane to the difference of neutron and proton analyzing powers measured in elastic np\vec{n}-\vec{p} scattering, and find them commensurate to those computed originally using the on-shell value of the ρ\rho-ω\omega mixing amplitude. The use of the on-shell ρ\rho-ω\omega mixing amplitude at q2=0q^2=0 has been called into question; rather, the amplitude is zero in a wide class of models. Our model possesses no contribution from ρ\rho-ω\omega mixing at q2=0q^2=0, and we find that omega-meson exchange suffices to explain the measured npn-p analyzing power difference~at~183 MeV.Comment: 20 pages, revtex, 3 uuencoded PostScript figure

    The COST292 experimental framework for TRECVID 2007

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    In this paper, we give an overview of the four tasks submitted to TRECVID 2007 by COST292. In shot boundary (SB) detection task, four SB detectors have been developed and the results are merged using two merging algorithms. The framework developed for the high-level feature extraction task comprises four systems. The first system transforms a set of low-level descriptors into the semantic space using Latent Semantic Analysis and utilises neural networks for feature detection. The second system uses a Bayesian classifier trained with a “bag of subregions”. The third system uses a multi-modal classifier based on SVMs and several descriptors. The fourth system uses two image classifiers based on ant colony optimisation and particle swarm optimisation respectively. The system submitted to the search task is an interactive retrieval application combining retrieval functionalities in various modalities with a user interface supporting automatic and interactive search over all queries submitted. Finally, the rushes task submission is based on a video summarisation and browsing system comprising two different interest curve algorithms and three features

    The COST292 experimental framework for TRECVID 2007

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    In this paper, we give an overview of the four tasks submitted to TRECVID 2007 by COST292. In shot boundary (SB) detection task, four SB detectors have been developed and the results are merged using two merging algorithms. The framework developed for the high-level feature extraction task comprises four systems. The first system transforms a set of low-level descriptors into the semantic space using Latent Semantic Analysis and utilises neural networks for feature detection. The second system uses a Bayesian classifier trained with a "bag of subregions". The third system uses a multi-modal classifier based on SVMs and several descriptors. The fourth system uses two image classifiers based on ant colony optimisation and particle swarm optimisation respectively. The system submitted to the search task is an interactive retrieval application combining retrieval functionalities in various modalities with a user interface supporting automatic and interactive search over all queries submitted. Finally, the rushes task submission is based on a video summarisation and browsing system comprising two different interest curve algorithms and three features

    Synergistic effect of phosphorus, nitrogen and silicon on flame retardancy properties of cotton fabric treated by sol-gel process

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    Purpose – The purpose of this paper is to develop the flame retardancy properties of cotton fabrics with treatment of phosphorus and nitrogen containing silane-based nanosol by sol-gel process. Design/methodology/approach – Nanosols containing tetraethoxysilane or (3-aminopropyl) triethoxysilane as precursors, (3-glycidyloxypropyl) trimethoxysilane as cross-linking agent and guanidine phosphate monobasic as flame retarding agent were impregnated on cotton fabrics. Flame retardancy properties of the fabric samples were determined by limited flame spread test and limited oxygen index (LOI) test. In addition, microstructural and surface morphological properties of the fabric samples were characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and scanning electron microscope. Findings – Depending on the limited flame spread test, the authors show that the coated fabric samples gain flame retardancy properties and the LOI value of the samples increased as to 45.7 per cent by the synergistic effect of phosphorus-nitrogen-silicon. Originality/value – There have some studies in flame retardancy behaviour of textiles. In this study, flame retardant cotton fabric with very low weight in grams was improved by sol-gel process. Moreover, ecological process was provided thanks to using halogen-free flame retardant. © 2016, © Emerald Group Publishing Limited
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