30,943 research outputs found
Phantom Thermodynamics Revisited
Although generalized Chaplygin phantom models do not show any big rip
singularities, we investigated k-essence models together with noncanonical
kinetic energy for which there might be a big rip future singularity in the
phantom region. We present our results by finely tuning the parameter ()
which is closely related to the canonical kinetic term in -essence
formalism. The scale factor could be negative and decreasing within a
specific range of during the initial evolutional period. There will be
no singularity for the scale factor for all times once is carefully
selected.Comment: 4 pages; 1 figur
Dispersion Relations for Waves propagating in Composite Fermion Gases
The discrete Uehling-Uhlenbeck equations are solved to study the propagation
of plane (sound) waves in a system of composite fermionic particles with
hard-sphere interactions and the filling factor () being 1/2. The
Uehling-Uhlenbeck collision sum, as it is highly nonlinear, is linearized
firstly and then decomposed by using the plane wave assumption. We compare the
dispersion relations thus obtained by the relevant Pauli-blocking parameter
which describes the different-statistics particles for the quantum analog of
the discrete Boltzmann system when is positive (Bose gases), zero
(Boltzmann gases), and negative (Fermi Gases). We found, as the effective
magnetic field being zero (=1/2 using the composite fermion formulation),
the electric and fluctuating (induced) magnetic fields effect will induce
anomalous dispersion relations.Comment: 13 pages with 2 figure
Possible Pressure Effect for Superconductors
We make an estimate of the possible range of induced by
high-pressure effects in post-metallic superconductors by using the theory of
{\it extended irreversible/reversible thermodynamics} and Pippard's length
scale. The relationship between the increment of the superconducting
temperature and the increase of the pressure is parabolic.Comment: 6 pages; 1999-March result
Stability of Quantum Fluids : Wavy Interface Effect
A numerical investigation for the stability of the incompressible slip flow
of normal quantum fluids (above the critical phase transition temperature)
inside a microslab where surface acoustic waves propagate along the walls is
presented. Governing equations and associated slip velocity and wavy interface
boundary conditions for the flow of normal fluids confined between elastic wavy
interfaces are obtained. The numerical approach is an extension (with a complex
matrix pre-conditioning) of the spectral method. We found that the critical
Reynolds number ( or the critical velocity) decreases significantly
once the slip velocity and wavy interface effects are present and the latter is
dominated ( mainly depends on the wavy interfaces).Comment: 4 Figures; 2004-Jan work
Possible Negative Pressure States in the Evolution of the Universe
Hydrodynamic derivation of the entrainment of matter induced by a surface
elastic wave propagating along the flexible vacuum-matter interface is
conducted by considering the nonlinear coupling between the interface and the
rarefaction effect. The critical reflux values associated with the product of
the second-order (unit) body forcing and the Reynolds number (representing the
viscous dissipations) decrease as the Knudsen number (representing the
rarefaction measure) increases from zero to 0.1. We obtained the critical
bounds for matter-freezed or zero-volume-flow-rate states corresponding to
specific Reynolds numbers (ratio of wave inertia and viscous dissipation
effects) and wave numbers which might be linked to the evolution of the
Universe. Our results also show that for positive evolution of the matter (the
maximum speed of the matter (gas) appears at the center-line) there might be
existence of negative pressure.Comment: 4 Figures in tota
Note on the Zero-Energy-Limit Solution for the Modified Gross-Pitaevskii Equation
The modified Gross-Pitaevskii equation was derived and solved to obtain the
1D solution in the zero-energy limit. This stationary solution could account
for the dominated contributions due to the kinetic effect as well as the
chemical potential in inhomogeneous Bose gases.Comment: 4 pages in total; 2002-May complete
Comments on "Microscale flow visualization"
We make comments on the presentation of Sinton's paper (Microfluidics and
Nanofluidics {\bf 1}: 2, 2004) about the microscale flow visualization since
the effects of the roughness along the microfabricated wall upon the current
macroflow visualization methods could be significant and cannot be neglected in
microdomain and even nanodomain.Comment: 3 page
Comments on "Evidence for Quantized Displacement in Macroscopic Nanomechanical Oscillators"
We make comments on Gaidarzhy {\it et al.}'s [{\it Phys. Rev. Lett.} 94,
030402 (2005)] letter.Comment: 3 page
Note on the 8-Knot
We define some physical variables associated with the traversing sequences of
electrons along the orbit which is a 2D projection of 8-knot. The
configuration is regular but the resulting contributions, which are related to
the physical variable, of those combinations from all the possible states to
the fixed spatial sites show certain irregular behavior near the over- or
under-crossing points of this knot. The possible explanation for this kind of
direct geometric consequences is made to linked to the physical insight.Comment: One Table and Two Figures; 1999-Feb. complete
Resonant States of Wave Propagation in Disordered System of Bosonic Particles
We demonstrate the effects of an induced disorder (or a free-orientation :
which is related to the relative direction of scattering of particles
w.r.t. to the normal of the propagating plane-wave front) upon the possible
resonance of the plane (sound) wave propagating in Bose gases by using the
quantum kinetic equations. We firstly present the diverse dispersion relations
obtained by the relevant Pauli-blocking parameter (which describes the Bose
particles when is positive) and the free-orientation and then,
based on the acoustic analog, address the possible resonant states.Comment: 7 Figures; 2004-March complete
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