51,695 research outputs found

    Formal Desingularization of Surfaces - The Jung Method Revisited -

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    In this paper we propose the concept of formal desingularizations as a substitute for the resolution of algebraic varieties. Though a usual resolution of algebraic varieties provides more information on the structure of singularities there is evidence that the weaker concept is enough for many computational purposes. We give a detailed study of the Jung method and show how it facilitates an efficient computation of formal desingularizations for projective surfaces over a field of characteristic zero, not necessarily algebraically closed. The paper includes a generalization of Duval's Theorem on rational Puiseux parametrizations to the multivariate case and a detailed description of a system for multivariate algebraic power series computations.Comment: 33 pages, 2 figure

    Stress corrosion crack inhibiting method for titanium

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    Addition of oxyanions to liquid solvents in excess of the number of chloride, bromide, or iodide ions present prevents cracking of titanium-aluminum alloys under exposure to aqueous and other solvent environments. The molar concentration of oxyanion is set from 10 to 100 times higher than concentration of halide ions

    Method of inhibiting stress corrosion cracks in titanium alloys Patent

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    Method to prevent stress corrosion cracking in titanium alloy

    Adjoint Computation for Hypersurfaces Using Formal Desingularizations

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    We show how to use formal desingularizations (defined earlier by the first author) in order to compute the global sections (also called adjoints) of twisted pluricanonical sheaves. These sections define maps that play an important role in the birational classification of schemes.Comment: 10 page

    On supercorrelated systems and phase space entrainment

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    It is demonstrated that power-laws which are modified by logarithmic corrections arise in supercorrelated systems. Their characteristic feature is the energy attributed to a state (or value of a general cost function) which depends nonlinearly on the phase space distribution of the constituents. A onedimensional dissipative deterministic model is introduced which is attracted to a supercorrelated state (phase space entrainment). Extensions of this particular model may have applications in the study of transport and equilibration phenomena, particularly for supply and information networks, or for chemical and biological nonequilibrium systems, while the qualitative arguments presented here are believed to be of more general interest.Comment: 12 pages - some technical material removed from second version, several explanatory comments and references added instea

    Magnetic fields in merging spirals - the Antennae

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    We present an extensive study of magnetic fields in a system of merging galaxies. We obtained for NGC4038/39 (the Antennae) radio total intensity and polarization maps at 8.44, 4.86 and 1.49GHz using the VLA in the C and D configurations. The radio thermal fraction was found to be about 50% at 10.45GHz, higher than in normal spirals. The mean total magnetic fields in both galaxies are about two times stronger (20microG) than in normal spirals. However,the degree of field regularity is rather low, implying tangling of the regular component in regions with interaction-enhanced star formation. Our data combined with those in HI, Halpha, X-rays and in far infrared allow us to study local interrelations between different gas phases and magnetic fields. We distinguish several radio-emitting regions with different physical properties and at various evolutionary stages. The whole overlapping region shows a coherent magnetic field structure, probably tracing the line of collision between the arms of merging spirals while the total radio emission reveals hidden star formation nests. The southern part of it is a particularly intense merger-triggered starburst. Highly tangled magnetic fields reach there strengths of 30microG, even larger than in both individual galaxies, possibly due to compression of the original fields pulled out from the parent disks. In the northeastern ridge, away from star-forming regions, the magnetic field is highly coherent with a strong regular component of 10microG tracing gas shearing motions along the tidal tail. Modelling Faraday rotation data show that we deal with a three-dimensionally curved structure of magnetic fields, becoming almost parallel to the sky plane in the southeastern part of the ridge.Comment: Accepted for publication in AA, 16 pages including 16 figures, high-res version at http://www.oa.uj.edu.pl/~chris/publ/4038.ps.g
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