22,879 research outputs found
Distinguishing Bulk-Diffusion from Surface-Desorption Limited Gas Release Processes
The release of a gas limited by surface desorption, or by diffusion from the
bulk of spherical pebbles is revisited. A method is proposed to identify the
release limiting process, by comparing a partial temperature ramp, up to
slightly beyond the release peak, followed by a rapid temperature drop, to a
second, full release ramp. Comparing the release curve from the second ramp to
that of the first one: i) the peak is unmoved in first order desorption
kinetics, and moves to higher temperature in the other cases, ii) as compared
to the Arrhenius analysis of the first curve, that of the second is, again,
identical in first order kinetics, in second order desorption it maintains the
slope but lowers the intercept at the reciprocal temperature origin, and it is
inapplicable in bulk diffusion kinetics.Comment: 5 pages, 3 figures. Published as Ricardo E. Avila, Jap. J. Appl.
Phys. 45, 9254 (2006
Extending tensors on polar manifolds
Let be a Riemannian manifold with a polar action by the Lie group ,
with section and generalized Weyl group . We show that
restriction to is a surjective map from the set of smooth
-invariant tensors on onto the set of smooth -invariant tensors on
. Moreover, we show that every smooth -invariant Riemannian metric
on can be extended to a smooth -invariant Riemannian metric on
with respect to which the -action remains polar with the same section
.Comment: arXiv admin note: text overlap with arXiv:1205.476
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