17,583 research outputs found
The Dropping of In-Medium Hadron Mass in Holographic QCD
We study the baryon density dependence of the vector meson spectrum using the
D4/D6 system together with the compact D4 baryon vertex. We find that the
vector meson mass decreases almost linearly in density at low density for small
quark mass, but saturates to a finite non-zero value for large density. We also
compute the density dependence of the mass and the
velocity. We find that in medium, our model is consistent with the GMOR
relation up to a few times the normal nuclear density. We compare our hQCD
predictions with predictions made based on hidden local gauge theory that is
constructed to model QCD.Comment: 20 pages, 7 figure
Non-thermal origin of nonlinear transport across magnetically induced superconductor-metal-insulator transition
We have studied the effect of perpendicular magnetic fields and temperatures
on the nonlinear electronic transport in amorphous Ta superconducting thin
films. The films exhibit a magnetic field induced metallic behavior intervening
the superconductor-insulator transition in the zero temperature limit. We show
that the nonlinear transport in the superconducting and metallic phase is of
non-thermal origin and accompanies an extraordinarily long voltage response
time.Comment: 5 pages, 4 figure
Growth Dynamics of Photoinduced Domains in Two-Dimensional Charge-Ordered Conductors Depending on Stabilization Mechanisms
Photoinduced melting of horizontal-stripe charge orders in
quasi-two-dimensional organic conductors
\theta-(BEDT-TTF)2RbZn(SCN)4[BEDT-TTF=bis(ethylenedithio)tetrathiafulvalene]
and
\alpha-(BEDT-TTF)2I3 is investigated theoretically. By numerically solving
the time-dependent Schr\"odinger equation, we study the photoinduced dynamics
in extended Peierls-Hubbard models on anisotropic triangular lattices within
the
Hartree-Fock approximation. The melting of the charge order needs more energy
for \theta-(BEDT-TTF)2RbZn(SCN)4 than for \alpha-(BEDT-TTF)2I3, which is a
consequence of the larger stabilization energy in \theta-(BEDT-TTF)2RbZn(SCN)4.
After local photoexcitation in the charge ordered states, the growth of a
photoinduced domain shows anisotropy. In \theta-(BEDT-TTF)2RbZn(SCN)4, the
domain hardly expands to the direction perpendicular to the horizontal-stripes.
This is because all the molecules on the hole-rich stripe are rotated in one
direction and those on the hole-poor stripe in the other direction. They
modulate horizontally connected transfer integrals homogeneously, stabilizing
the charge order stripe by stripe. In \alpha-(BEDT-TTF)2I3, lattice distortions
locally stabilize the charge order so that it is easily weakened by local
photoexcitation. The photoinduced domain indeed expands in the plane. These
results are consistent with recent observation by femtosecond reflection
spectroscopy.Comment: 9 pages, 8 figures, to appear in J. Phys. Soc. Jpn. Vol. 79 (2010)
No.
Efficient Coil Design by Electromagnetic Topology Optimization for Electromagnetic Sharp Edge Forming of DP980 Steel Sheet
This paper proposes a design method of the tool coil by topology optimization for the
electromagnetic sharp edge forming process. Topology optimization is an approach that
optimizes material configuration in a given domain to meet the design requirements. The
design problem for the tool coil is defined as enhancing efficiency of the forming process
and optimization problem is set to be maximization of the Lorentz force induced on the tool
coil. A new topology optimization formulation based on the numerical methods for
electromagnetism using FEM and BEM is developed for maximization of the Lorentz force.
Optimum design of the tool coil is obtained by the topology optimization using the element
density approach. The optimized result is compared with other coils which have different
configurations to show the effectiveness of the proposed method. The idea of applying
topology optimization to the design of the tool coil is successful and this formulation deals
effectively for the optimization problems
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