5,503 research outputs found
Computational procedure for finite difference solution of one-dimensional heat conduction problems reduces computer time
Computational procedure reduces the numerical effort whenever the method of finite differences is used to solve ablation problems for which the surface recession is large relative to the initial slab thickness. The number of numerical operations required for a given maximum space mesh size is reduced
Bound States of (Anti-)Scalar-Quarks in SU(3)_c Lattice QCD
Light scalar-quarks \phi (colored scalar particles or idealized diquarks) and
their color-singlet hadronic states are studied with quenched SU(3)_c lattice
QCD in terms of mass generation. We investigate ``scalar-quark mesons''
\phi^\dagger \phi and ``scalar-quark baryons'' \phi\phi\phi as the bound states
of scalar-quarks \phi. We also investigate the bound states of scalar-quarks
\phi and quarks \psi, i.e., \phi^\dagger \psi, \psi\psi\phi and \phi\phi\psi,
which we name ``chimera hadrons''. All the new-type hadrons including \phi are
found to have a large mass due to large quantum corrections by gluons, even for
zero bare scalar-quark mass m_\phi=0 at a^{-1}\sim 1{\rm GeV}. We conjecture
that all colored particles generally acquire a large effective mass due to
dressed gluon effects.Comment: Talk given at The 17th International Spin Physics Symposium
(SPIN2006), Kyoto, Japan, 2-7 Oct 200
Detection of flux emergence, splitting, merging, and cancellation of network field. I Splitting and Merging
Frequencies of magnetic patch processes on supergranule boundary, namely flux
emergence, splitting, merging, and cancellation, are investigated through an
automatic detection. We use a set of line of sight magnetograms taken by the
Solar Optical Telescope (SOT) on board Hinode satellite. We found 1636 positive
patches and 1637 negative patches in the data set, whose time duration is 3.5
hours and field of view is 112" \times 112". Total numbers of magnetic
processes are followed: 493 positive and 482 negative splittings, 536 positive
and 535 negative mergings, 86 cancellations, and 3 emergences. Total numbers of
emergence and cancellation are significantly smaller than those of splitting
and merging. Further, frequency dependences of merging and splitting processes
on flux content are investigated. Merging has a weak dependence on flux content
only with a power- law index of 0.28. Timescale for splitting is found to be
independent of parent flux content before splitting, which corresponds to \sim
33 minutes. It is also found that patches split into any flux contents with a
same probability. This splitting has a power-law distribution of flux content
with an index of -2 as a time independent solution. These results support that
the frequency distribution of flux content in the analyzed flux range is
rapidly maintained by merging and splitting, namely surface processes. We
suggest a model for frequency distributions of cancellation and emergence based
on this idea.Comment: 32 pages, 10 figures, 1 table, accepted to Ap
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Surface damage resulting from rolling contact operating in magnetic field
This paper describes the effects of magnetic field in rolling contact tests of steel by using a two-disc configuration and the investigation of mechanisms involved.
Two contact conditions, namely pure rolling and rolling with 10% sliding were used together with 0.4 and 1.1 Tesla horizontal static magnetic fields created by permanent magnets. Results of optical and scanning electron microscope observations point out that finer wear particles and smoother worn surfaces are produced in the presence of a magnetic field. It is proposed that finer wear particles result from the movement of subsurface crack initiation towards the surface due to the action of magnetic field
Single domain YBCO/Ag bulk superconductors fabricated by seeded infiltration and growth
We have applied the seeded infiltration and growth (IG) technique to the processing of samples containing Ag in an attempt to fabricate Ag-doped Y-Ba-Cu-O (YBCO) bulk superconductors with enhanced mechanical properties. The IG technique has been used successfully to grow bulk Ag-doped YBCO superconductors of up to 25 mm in diameter in the form of single grains. The distribution of Ag in the parent Y-123 matrix fabricated by the IG technique is observed to be at least as uniform as that in samples grown by conventional top seeded melt growth (TSMG). Fine Y-211 particles were observed to be embedded within the Y-123 matrix for the IG processed samples, leading to a high critical current density, Jc, of over 70 kA/cm2 at 77.3 K in self-field. The distribution of Y-211 in the IG sample microstructure, however, is inhomogeneous, which leads to a variation in the spatial distribution of Jc throughout the bulk matrix. A maximum-trapped field of around 0.43 T at 1.2 mm above the sample surface (i.e. including 0.7 mm for the sensor mould thickness) is observed at liquid nitrogen temperature, despite the relatively small grain size of the sample (20 mm diameter Ă— 7 mm thickness)
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