31,529 research outputs found
Theoretical Study for Deformation Kinetics of Glassy Solid Helium within Cylindrical Microtubes
The deformation kinetics for glassy solid helium confined in microscopic
domain at very low temperature regime was investigated using a transition-rate
model considering the shear thinning behavior which means, once material being
subjected to high shear rates, the viscosity diminishes with increasing shear
rate. The preliminary results show that there might be nearly frictionless
fields for rate of deformation due to the almost vanishing shear stress in
microtubes at very low temperature regime subjected to some surface conditions
: The relatively larger roughness (compared to the macroscopic domain) inside
microtubes and the slip. As the pore size decreases, the surface-to-volume
ratio increases and therefore, surface roughness will greatly affect the
deformation kinetics in microtubes. By using the boundary perturbation method,
we obtained a class of temperature and activation energy dependent fields for
the deformation kinetics at low temperature regime with the presumed small wavy
roughness distributed along the walls of an cylindrical microtube. The critical
deformation kinetics of the glassy matter is dependent upon the temperature,
activation energy, activation volume, orientation dependent and is proportional
to the (referenced) shear rate, the slip length, the amplitude and the
orientation of the wavy-roughness. Finally, we also discuss the quantitative
similarity between our results with Ray and Hallock [Phys. Rev. Lett. {\bf
100}, 235301 (2008)].Comment: 9 figure
Possible Frictionless States at Room-Temperature Regime for Many Fermions in Confined Domain
We investigate the possible frictionless transport of many composite
(condensed) fermions at room temperature regime along an annular tube with
transversely wavy-corrugations by using the verified transition-rate model and
boundary perturbation approach. We found that for certain activation volume and
energy there exist possible frictionless states at room temperature regime
Gravity-driven Transport along Cylindrical Topological Defects : Possible Dark Matter and Nearly Frictionless States
The gravity-driven flow along an annular topological defect (string) with
transversely corrugations is investigated by using the verified transition-rate
model and boundary perturbation method. We found that for certain activation
volume and energy there exists possible frictionless states which might be
associated with the missing momentum of inertia or dark matter.Comment: two figure
Note on "Sonic Mach cones induced by fast partons in a perturbative quark-gluon plasma" arXiv:0802.2254
We make remarks on Neufeld {\it et al.}'s [{\it Phys. Rev. C} 78, 041901(R)
(2008), arXiv:0802.2254] paper especially about the Mach cone formation. We
argue that the original bow shock structure (as a fast parton moving through a
quark-gluon plasma) has been smeared out after the approximations made by
Neufeld {\it et al.
Population Inversion, Negative Temperature, and Quantum Degeneracies
We revisit the basic principle for lasing : Population inversion which is
nevertheless closely linked to the negative temperature state in
non-equilibrium thermodynamics. With the introduction of quantum degeneracies,
we also illustrate their relationship with the lasing via the tuning of
population inversion.Comment: two figure
Rapid Transport of Glassy Supersolid Helium in Wavy-Rough Nanpores
We show that the presumed wavy roughness distributed along the wall of
different nanopores (radius : a around 3.5 nm for Vycor or a silica glass;
around 245 nm for porous gold) will induce larger volume flow rates of solid
helium (of which there is a minimum) which might explain reported experimental
differences of the supersolid fractions observed so far.Comment: one Figur
Possible Routes to Frictionless Transport of Electronic Fluids in High-Temperature Superconductors
Electric-field-driven transport of electronic fluids in metallic glasses as
well as three-dimensional amorphous superconductors are investigated by using
the verified approach which has been successfully adopted to study the critical
transport of glassy solid helium in very low temperature environment. The
critical temperatures related to the nearly frictionless transport of
electronic fluids were found to be directly relevant to the superconducting
temperature of amorphous superconductors after selecting specific activation
energies. Our results imply that optimal shear-thinning is an effective way to
reach high-temperature charged superfluidity or superconductivity.Comment: four figure
Possible Frictionless Regime for Ultra-High Temperature Amorphous Matter
The almost frictionless transport of the very-high temperature amorphous
matter which resembles the color glass condensate (possibly having much of
their origin in the RHIC heavy ion collisions) in a confined annular tube with
transversely corrugations is investigated by using the verified transition-rate
model and boundary perturbation method. We found that for certain activation
volume and energy there exist possible frictionless states which might be
associated with the perfect fluid formation during the early expansion stage in
RHIC Au+Au collisions. We also address the possible similar scenario in LHC
Pb+Pb collisions considering the possible perfect fluid formation in ultra-high
temperature transport of amorphous matter
Comments on "Effects of wall roughness on flow in nanochannels"
We make remarks on Sofos {\it et al.}'s [{\it Phys. Rev. E} 79, 026305
(2009)] paper. The focus is about the monotonicity of the slip length of which
it is different from previous similar numerical simulation. We also offer a
possible explanation for this
Comments on "Slip coefficient in nanoscale pore flow" (arXiv:0805.1666)
We make some remarks on Sokhan and Quirke's [{\it Phys. Rev. E} 78, 015301(R)
(2008)] paper (arXiv:0805.1666). Sokhan and Quirke mentioned that, considering
their main result, {the slip coefficient is independent of the external force
(flux)} which is not consistent with previous measurements and approaches. We
also discuss the sudden changes of the slip coefficient for larger Knudsen
numbers or smaller nanopores
- …