75,731 research outputs found
Stability Of contact discontinuity for steady Euler System in infinite duct
In this paper, we prove structural stability of contact discontinuities for
full Euler system
Behavior of the collective rotor in wobbling motion
The behavior of the collective rotor in wobbling motion is investigated
within the particle-rotor model for the nucleus Pr by transforming the
wave functions from the -representation to the -representation. After
reproducing the experimental energy spectra and wobbling frequencies, the
evolution of the wobbling mode in Pr, from transverse at low spins to
longitudinal at high spins, is illustrated by the distributions of the total
angular momentum in the intrinsic reference frame (azimuthal plot). Finally,
the coupling schemes of the angular momenta of the rotor and the high-
particle for transverse and longitudinal wobbling are obtained from the
analysis of the probability distributions of the rotor angular momentum
(-plots) and their projections onto the three principal axes (-plots).Comment: 21 pages, 9 page
Hawking radiation from the Schwarzschild black hole with a global monopole via gravitational anomaly
Hawking flux from the Schwarzschild black hole with a global monopole is
obtained by using Robinson and Wilczek's method. Adopting a dimension reduction
technique, the effective quantum field in the (3+1)--dimensional global
monopole background can be described by an infinite collection of the
(1+1)--dimensional massless fields if neglecting the ingoing modes near the
horizon, where the gravitational anomaly can be cancelled by the
(1+1)--dimensional black body radiation at the Hawking temperature.Comment: 4 pages, no figure, 3nd revsion with one reference adde
Delay-induced multiple stochastic resonances on scale-free neuronal networks
We study the effects of periodic subthreshold pacemaker activity and
time-delayed coupling on stochastic resonance over scale-free neuronal
networks. As the two extreme options, we introduce the pacemaker respectively
to the neuron with the highest degree and to one of the neurons with the lowest
degree within the network, but we also consider the case when all neurons are
exposed to the periodic forcing. In the absence of delay, we show that an
intermediate intensity of noise is able to optimally assist the pacemaker in
imposing its rhythm on the whole ensemble, irrespective to its placing, thus
providing evidences for stochastic resonance on the scale-free neuronal
networks. Interestingly thereby, if the forcing in form of a periodic pulse
train is introduced to all neurons forming the network, the stochastic
resonance decreases as compared to the case when only a single neuron is paced.
Moreover, we show that finite delays in coupling can significantly affect the
stochastic resonance on scale-free neuronal networks. In particular,
appropriately tuned delays can induce multiple stochastic resonances
independently of the placing of the pacemaker, but they can also altogether
destroy stochastic resonance. Delay-induced multiple stochastic resonances
manifest as well-expressed maxima of the correlation measure, appearing at
every multiple of the pacemaker period. We argue that fine-tuned delays and
locally active pacemakers are vital for assuring optimal conditions for
stochastic resonance on complex neuronal networks.Comment: 7 two-column pages, 5 figures; accepted for publication in Chao
Simulating radiative cooling/heating using BES-CFD coupled simulation
The radiant cooling and heating system like the thermo-active concrete core system (TACS) has long been recognized as an alternative to the conventional all-air system, especially in Europe. The latest developments in simulation tools for radiative cooling/heating focused on the explicit plant definition in the simulation tools , i.e. how to simulate what is behind the radiant surfaces There is less attention on what is going on between radiant surface and the occupied zone. This paper explores the advantages of using the coupled simulation between building energy simulation (BES) and computational fluid dynamics (CFD) simulation in designing space conditioning by radiative cooling/heating. The way the coupled simulation treats the convection coefficient definition can be utilised to improve the prediction of thermal comfort and energy consumption
Chemical composition of 90 F and G disk dwarfs
High resolution, high S/N spectra have been obtained for a sample of 90 F and
G main-sequence disk stars covering the metallicity range -1.0 < [Fe/H] < +0.1,
and have been analysed in a parallel way to the work of Edvardsson et al.
(1993). Effective temperatures are based on the Alonso et al. (1996)
calibration of color indices and surface gravities are calculated from
Hipparcos parallaxes, which also allow more accurate ages to be calculated. In
addition, more reliable kinematical parameters are derived from Hipparcos
distances and proper motions. Finally, a larger spectral coverage, 5600 - 8800
A, makes it possible to improve the abundance accuracy by studying more lines
and to discuss several elements not included in the work of Edvardsson et al.
The present paper provides the data and discusses some general results of the
abundance survey. A group of stars in the metallicity range of -1.0 < [Fe/H] <
-0.6 having a small mean Galactocentric distance in the stellar orbits, Rm < 7
kpc, are shown to be older than the other disk stars and probably belong to the
thick disk. Excluding these stars, a slight decreasing trend of [Fe/H] with
increasing Rm and age is found, but a large scatter in [Fe/H] (up to 0.5 dex)
is present at a given age and Rm. The derived trends of O, Mg, Si, Ca, Ti, Ni
and Ba as a function of [Fe/H] agree rather well with those of Edvardsson et
al., but the overabundance of Na and Al for metal-poor stars found in their
work is not confirmed. Furthermore, the Galactic evolution of elements not
included in Edvardsson et al., K, V and Cr, is studied.Comment: 16 pages with 10 figures. Accepted for publication in A&A
Ground-state properties of one-dimensional ultracold Bose gases in a hard-wall trap
We investigate the ground state of the system of N bosons enclosed in a
hard-wall trap interacting via a repulsive or attractive -function
potential. Based on the Bethe ansatz method, the explicit ground state wave
function is derived and the corresponding Bethe ansatz equations are solved
numerically for the full physical regime from the Tonks limit to the strongly
attractive limit. It is shown that the solution takes different form in
different regime. We also evaluate the one body density matrix and second-order
correlation function of the ground state for finite systems. In the Tonks limit
the density profiles display the Fermi-like behavior, while in the strongly
attractive limit the Bosons form a bound state of N atoms corresponding to the
N-string solution. The density profiles show the continuous crossover behavior
in the entire regime. Further the correlation function indicates that the Bose
atoms bunch closer as the interaction constant decreases.Comment: 7 pages, 6 figures, version published in Phys. Rev.
Multidimensional Conservation Laws: Overview, Problems, and Perspective
Some of recent important developments are overviewed, several longstanding
open problems are discussed, and a perspective is presented for the
mathematical theory of multidimensional conservation laws. Some basic features
and phenomena of multidimensional hyperbolic conservation laws are revealed,
and some samples of multidimensional systems/models and related important
problems are presented and analyzed with emphasis on the prototypes that have
been solved or may be expected to be solved rigorously at least for some cases.
In particular, multidimensional steady supersonic problems and transonic
problems, shock reflection-diffraction problems, and related effective
nonlinear approaches are analyzed. A theory of divergence-measure vector fields
and related analytical frameworks for the analysis of entropy solutions are
discussed.Comment: 43 pages, 3 figure
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