293 research outputs found
Formation of singularities for equivariant 2+1 dimensional wave maps into the two-sphere
In this paper we report on numerical studies of the Cauchy problem for
equivariant wave maps from 2+1 dimensional Minkowski spacetime into the
two-sphere. Our results provide strong evidence for the conjecture that large
energy initial data develop singularities in finite time and that singularity
formation has the universal form of adiabatic shrinking of the degree-one
harmonic map from into .Comment: 14 pages, 5 figures, final version to be published in Nonlinearit
Gravitating monopoles and black holes in Einstein-Born-Infeld-Higgs model
We find static spherically symmetric monopoles in Einstein-Born-Infeld-Higgs
model in 3+1 dimensions. The solutions exist only when a parameter \a
(related to the strength of Gravitational interaction) does not exceed certain
critical value. We also discuss magnetically charged non Abelian black holes in
this model. We analyse these solutions numerically.Comment: LaTex,10 pages, 5figure
Three-dimensional finite-element elastic analysis of a thermally cycled single-edge wedge geometry specimen
An elastic stress analysis was performed on a wedge specimen (prismatic bar with single-wedge cross section) subjected to thermal cycles in fluidized beds. Seven different combinations consisting of three alloys (NASA TAZ-8A, 316 stainless steel, and A-286) and four thermal cycling conditions were analyzed. The analyses were performed as a joint effort of two laboratories using different models and computer programs (NASTRAN and ISO3DQ). Stress, strain, and temperature results are presented
DMD Analysis of Experimental PIV Data of a Swirled Jet
This paper concerns the study of high Reynolds and high swirl number flow through the use of PIV measurements and Dynamic Mode Decomposition (DMD) analysis. Principles governing DMD are briefly recalled, then the use of DMD is demonstrated by analysing the acquired PIV data in order to study the dominant dynamics of the system and extracting relevant morphology via DMD modes, focusing the attention on phenomenon known as Precessing Vortex Core (PVC)
Gravitating dyons and dyonic black holes in Einstein-Born-Infeld-Higgs model
We find static spherically symmetric dyons in Einstein-Born-Infeld-Higgs
model in 3+1 dimensions. The solutions share many features with the gravitating
monopoles in the same model. In particular, they exist only up to some critical
value of a parameter \a related to the strength of the gravitational
interaction. We also study dyonic non-Abelian black holes. We analyse these
solutions numerically.Comment: Minor modifications, few more references added. To appear in Phys.
Lett.
Dirty blackholes: Thermodynamics and horizon structure
Considerable interest has recently been expressed in (static spherically
symmetric) blackholes in interaction with various classical matter fields (such
as electromagnetic fields, dilaton fields, axion fields, Abelian Higgs fields,
non--Abelian gauge fields, {\sl etc}). A common feature of these investigations
that has not previously been remarked upon is that the Hawking temperature of
such systems appears to be suppressed relative to that of a vacuum blackhole of
equal horizon area. That is: . This paper will argue that this suppression is generic.
Specifically, it will be shown that
Here is an integral quantity, depending on the distribution of
matter, that is guaranteed to be positive if the Weak Energy Condition is
satisfied. Several examples of this behaviour will be discussed.
Generalizations of this behaviour to non--symmetric non--static blackholes are
conjectured.Comment: [minor revisions] 22 pages, RevTe
The fate of Reissner-Nortstr\"{o}m black hole in the Einstein-Yang-Mills-Higgs system
We study about an evaporating process of black holes in SO(3)
Einstein-Yang-Mills-Higgs system. We consider a massless scalar field which
couple neither with the Yang-Mills field nor with the Higgs field surrounding
the black hole. We discuss differences in evaporating rate between a monopole
black hole and a Reissner-Nortstr\"{o}m (RN) black hole.Comment: 9 pages, 8 figure
Internal structure of Skyrme black hole
We consider the internal structure of the Skyrme black hole under a static
and spherically symmetric ansatz. $@u8(Be concentrate on solutions with the
node number one and with the "winding" number zero, where there exist two
solutions for each horizon radius; one solution is stable and the other is
unstable against linear perturbation. We find that a generic solution exhibits
an oscillating behavior near the sigularity, as similar to a solution in the
Einstein-Yang-Mills (EYM) system, independently to stability of the solution.
Comparing it with that in the EYM system, this oscillation becomes mild because
of the mass term of the Skyrme field. We also find Schwarzschild-like
exceptional solutions where no oscillating behavior is seen. Contrary to the
EYM system where there is one such solution branch if the node number is fixed,
there are two branches corresponding to the stable and the unstable ones.Comment: 5 pages, 4 figures, some contents adde
Stability of Non-Abelian Black Holes
Two types of self-gravitating particle solutions found in several theories
with non-Abelian fields are smoothly connected by a family of non-trivial black
holes. There exists a maximum point of the black hole entropy, where the
stability of solutions changes. This criterion is universal, and the changes in
stability follow from a catastrophe-theoretic analysis of the potential
function defined by black hole entropy.Comment: 4 Figures to be sent on request,8 pages, WU-AP/33/9
Transport Coefficients for Granular Media from Molecular Dynamics Simulations
Under many conditions, macroscopic grains flow like a fluid; kinetic theory
pred icts continuum equations of motion for this granular fluid. In order to
test the theory, we perform event driven molecular simulations of a
two-dimensional gas of inelastic hard disks, driven by contact with a heat
bath. Even for strong dissipation, high densities, and small numbers of
particles, we find that continuum theory describes the system well. With a bath
that heats the gas homogeneously, strong velocity correlations produce a
slightly smaller energy loss due to inelastic collisions than that predicted by
kinetic theory. With an inhomogeneous heat bath, thermal or velocity gradients
are induced. Determination of the resulting fluxes allows calculation of the
thermal conductivity and shear viscosity, which are compared to the predictions
of granular kinetic theory, and which can be used in continuum modeling of
granular flows. The shear viscosity is close to the prediction of kinetic
theory, while the thermal conductivity can be overestimated by a factor of 2;
in each case, transport is lowered with increasing inelasticity.Comment: 14 pages, 17 figures, 39 references, submitted to PRE feb 199
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