5,797 research outputs found
Possible Enhanced Flux of Glassy Solid Helium in Cylindrical Corrugated Nanopores
By using the glassy (helium-)fluid model and boundary perturbation method, we
can obtain the velocity fields (as well as the flow rate; up to the second
order) inside the wavy-rough cylindrical nanopores which are of the same size
as those samples prepared by Kim and Chan as well as Day {\it et al.} Our
results show that the velocities measured in porous Vycor samples could be
reproduced by carefully selecting relevant parameters but those in glass
capillaries are difficult to obtain.Comment: 2 figure
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
Comments on "Attainable conditions and exact invariant for the time-dependent harmonic oscillator"
We make remarks on Fern\'{a}ndez Guasti's paper [{\it J. Phys. A: Math. Gen.}
39 (2006) 11825-11832] by pointing out some mistakes Fern\'{a}ndez Guasti
derived therein.Comment: Comments for ; 2 Pages in tota
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
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
Possible Orientation Effects to Phase Diagram of Strange Matter
We obtain possibly valuable information about the orientation-tuning of phase
diagram of superdense nuclear matter at high fermion as well as boson number
density but low temperature, which is not accessible to relativistic heavy ion
collision experiments. Our results resemble those proposed before by Alford.
Possible observational signatures associated with the theoretically proposed
states of matter inside compact stars are discussed as well.Comment: 3 Figures; 2006-Jan. work
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
Transport induced by Density Waves in a Andreev-Lifshitz Supersolid
Macroscopic derivation of the entrainment in in a Andreev-Lifshitz Supersolid
induced by a surface elastic wave propagating along the flexible interface is
conducted by considering the nonlinear coupling between the interface and the
rarefaction effect. We obtain the critical bounds for zero-volume-flow-rate
states corresponding to specific rarefaction measure and wave number which is
relevant to the rather small critical velocity of supersolid flows reported by
Kim and Chan.Comment: 2 Figures in total, 2006-March work
Possible Structures of Sprites
Upon using the hydrodynamic analog we can derive some families of stationary
Beltrami field-like solutions from the free Maxwell equations in vacuum. These
stationary electromagnetic fields are helical and/or column-like once they are
represented in a suitable frame of reference. Possible dendritic and
jelly-fish-like patterns of sprites are demonstrated.Comment: 2005 Feb. works; 5 figure
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
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