218,893 research outputs found
Algebraic cobordism of bundles on varieties
The double point relation defines a natural theory of algebraic cobordism for
bundles on varieties. We construct a simple basis (over the rationals) of the
corresponding cobordism groups over Spec(C) for all dimensions of varieties and
ranks of bundles. The basis consists of split bundles over products of
projective spaces. Moreover, we prove the full theory for bundles on varieties
is an extension of scalars of standard algebraic cobordism.Comment: 24 pages, reference adde
The GSFC NASTRAN thermal analyzer new capabilities
An overview of four analysis capabilities, which developed and integrated into the NASTRAN Thermal Analyzer, is given. To broaden the scope of applications, these additions provide the NTA users with the following capabilities: (1) simulating a thermal louver as a means of the passive thermal control, (2) simulating a fluid loop for transporting energy as a means of the active thermal control, (3) condensing a large sized finite element model for an efficient transient thermal analysis, and (4) entering multiple boundary condition sets in a single submission for execution in steady state thermal analyses
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Elicitation and representation of expert knowledge for computer aided diagnosis in mammography
To study how professional radiologists describe, interpret and make decisions about micro-calcifications in mammograms. The purpose was to develop a model of the radiologists' decision making for use in CADMIUM II, a computerized aid for mammogram interpretation that combines symbolic reasoning with image processing
SETI low-frequency feed design study for DSS 24
The Search for Extraterrestrial Intelligence Sky Survey project requires operation from 1 to 10 GHz on the beam waveguide (BWG) antenna DSS 24. The BWG reflectors are undersized in the 1- to 3.02-GHz range, resulting in poor performance. Horn designs and a method for implementing 1- to 3.02-GHz operation on DSS 24 are presented. A combination of a horn and a shaped feed reflector placed above the main reflector is suggested. The horn and feed reflector could be hidden in the RF shadow of the subreflector and struts. Results from computer analysis of this design indicate that adequate performance could be achieved
Magnetization-controlled spin transport in DyAs/GaAs layers
Electrical transport properties of DyAs epitaxial layers grown on GaAs have
been investigated at various temperatures and magnetic fields up to 12T. The
measured longitudinal resistances show two distinct peaks at fields around 0.2
and 2.5T which are believed to be related to the strong spin-disorder
scattering occurring at the phase transition boundaries induced by external
magnetic field. An empirical magnetic phase diagram is deduced from the
temperature dependent experiment, and the anisotropic transport properties are
also presented for various magnetic field directions with respect to the
current flow.Comment: 3 pages with 3 figure
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