31,298 research outputs found
Estimated ion mobilities for some air constituents
Estimating ion mobilities and ion-neutral collisions in upper atmospher
Field dependence of gaseous ion mobility: Test of approximate formulas
The accuracies of three approximate formulas were tested by comparison with special cases for which accurate results could be found. The Wannier free flight theory was found to be superior, and can be extended to yield a formula without further adjustable constants that gives an exact result at low electric fields and good results at medium and high fields. It is applicable for any ion neutral force law and mass ratio
Nonadditivity of intermolecular forces - Effects on the third virial coefficient
Effects of nonadditive three body forces on third virial coefficien
Critical Evaluation and Compilation of Viscosity and Diffusivity Data Semiannual Status Report No. 1, Jul. 1 - Dec. 31, 1965
Compilation and evaluation of diffusivity and viscosity data on gas and liquid turbulent flow system
Collision Integrals for the Transport Properties of Dissociating Air at High Temperatures
Collision integrals for the transport properties of dissociating air at high temperature
Composition dependence of ion diffusion coefficients in gas mixtures at arbitrary field strengths
Expressions for the diffusion coefficient of ions in gas mixtures are obtained from momentum transfer theory, and are given in terms of the diffusion coefficients and drift velocities of the ions in the pure component gases. Blanc's law holds exactly at all field strengths if the mean free time between collisions is independent of velocity (Maxwell model), but otherwise there may be either positive or negative deviations from Blanc's law at high fields. Such deviations are of comparable magnitude for the diffusion coefficients and the mobility, but are not identical. Specific cases of inverse-power potentials are treated in further detail, and some numerical examples are given for rigid-sphere interactions
Feshbach Resonance Management of Bose-Einstein Condensates in Optical Lattices
We analyze gap solitons in trapped Bose-Einstein condensates (BECs) in
optical lattice potentials under Feshbach resonance management. Starting with
an averaged Gross-Pitaevsky (GP) equation with a periodic potential, we employ
an envelope wave approximation to derive coupled-mode equations describing the
slow BEC dynamics in the first spectral gap of the optical lattice. We
construct exact analytical formulas describing gap soliton solutions and
examine their spectral stability using the Chebyshev interpolation method. We
show that these gap solitons are unstable far from the threshold of local
bifurcation and that the instability results in the distortion of their shape.
We also predict the threshold of the power of gap solitons near the local
bifurcation limit.Comment: 8 pages, 4 figures (1 with six parts, 3 with two parts
Active Region Moss: Doppler Shifts from Hinode/EIS Observations
Studying the Doppler shifts and the temperature dependence of Doppler shifts
in moss regions can help us understand the heating processes in the core of the
active regions. In this paper we have used an active region observation
recorded by the Extreme-ultraviolet Imaging Spectrometer (EIS) onboard Hinode
on 12-Dec-2007 to measure the Doppler shifts in the moss regions. We have
distinguished the moss regions from the rest of the active region by defining a
low density cut-off as derived by Tripathi et al. (2010). We have carried out a
very careful analysis of the EIS wavelength calibration based on the method
described in Young et al. (2012). For spectral lines having maximum sensitivity
between log T = 5.85 and log T = 6.25 K, we find that the velocity distribution
peaks at around 0 km/s with an estimated error of 4-5 km/s. The width of the
distribution decreases with temperature. The mean of the distribution shows a
blue shift which increases with increasing temperature and the distribution
also shows asymmetries towards blue-shift. Comparing these results with
observables predicted from different coronal heating models, we find that these
results are consistent with both steady and impulsive heating scenarios.
However, the fact that there are a significant number of pixels showing
velocity amplitudes that exceed the uncertainty of 5 km s is suggestive
of impulsive heating. Clearly, further observational constraints are needed to
distinguish between these two heating scenarios.Comment: 21 pages (single column), 7 figures, Accepted for Publication in The
Astrophysical Journa
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