1,864 research outputs found

    Homological invariants associated to semi-dualizing bimodules

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    Cohen-Macaulay dimension for modules over a commutative noetherian local ring has been defined by A. A. Gerko. That is a homological invariant sharing many properties with projective dimension and Gorenstein dimension. The main purpose of this paper is to extend the notion of Cohen-Macaulay dimension for modules over commutative noetherian local rings to that for bounded complexes over non-commutative noetherian rings.Comment: 19 pages, to appear in J. Math. Kyoto Uni

    Upper Cohen-Macaulay Dimension

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    In this paper, we define a homological invariant for finitely generated modules over a commutative noetherian local ring, which we call upper Cohen-Macaulay dimension. This invariant is quite similar to Cohen-Macaulay dimension that has been introduced by Gerko. Also we define a homological invariant with respect to a local homomorphism of local rings. This invariant links upper Cohen-Macaulay dimension with Gorenstein dimension.</p

    Local cohomology based on a nonclosed support defined by a pair of ideals

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    We introduce an idea for generalization of a local cohomology module, which we call a local cohomology module with respect to a pair of ideals (I,J), and study their various properties. Some vanishing and nonvanishing theorems are given for this generalized version of local cohomology. We also discuss its connection with the ordinary local cohomology.Comment: 28 pages, minor corrections, to appear in J. Pure Appl. Algebr

    Specific-heat study on successive magnetic transitions in α-Dy2S3 single crystals under magnetic fields

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    Specific heat measurements in magnetic fields have been performed on !-Dy2S3 single crystal that shows successive magnetic transitions at TN1 = 11.4 K and TN2 = 6.4 K. The specific heat in no magnetic field exhibits sharp peaks at both temperatures of TN1 and TN2.The change of magnetic entropy across each transition is estimated as Rln2/2 per mol-Dy,which suggests magnetic moments on only one Dy site between two crystallographically inequivalent Dy sites order at each transition temperature. When the magnetic field is applied along the b-axis of the orthorhombic system, two peaks of the specific heat shift toward lower temperatures. On the other hand, the magnetic field perpendicular to the b-axis shifts the peaks toward higher temperatures. The TN1 shifts to 9.6 K (H// b) and 12.5 K (H⊥b) under the magnetic field of 2 T. The peak of TN2 broadens gradually with increasing magnetic field for each direction, and the peak is consequently obscure under the field of 2 T

    Study on problems in detecting plural cracks by alternating flux leakage testing using 3D nonlinear eddy current analysis

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    The alternating magnetic flux leakage testing is used for the detection of cracks in a steel plate. A new technique of how to detect plural cracks, which are located at a very short distance from each other, using the parallel (x-) component of the leakage flux density is proposed. The behavior of leakage flux is examined using a three-dimensional edge-based hexahedral finite-element method. The effects of dimensions of search coils and cracks on the detection accuracy are illustrated. </p
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