23,507 research outputs found
"Possible Definitions of an ’A Priori’ Granule\ud in General Rough Set Theory" by A. Mani
We introduce an abstract framework for general rough set theory from a mereological perspective and consider possible concepts of ’a priori’ granules and granulation in the same. The framework is ideal for relaxing many of the\ud
relatively superfluous set-theoretic axioms and for improving the semantics of many relation based, cover-based and dialectical rough set theories. This is a\ud
relatively simplified presentation of a section in three different recent research papers by the present author.\u
Edwards thermodynamics of the jamming transition for frictionless packings: ergodicity test and role of angoricity and compactivity
This paper illustrates how the tools of equilibrium statistical mechanics can
help to explain a far-from-equilibrium problem: the jamming transition in
frictionless granular materials. Edwards ideas consist of proposing a
statistical ensemble of volume and stress fluctuations through the
thermodynamic notion of entropy, compactivity, X, and angoricity, A (two
temperature-like variables). We find that Edwards thermodynamics is able to
describe the jamming transition (J-point). Using the ensemble formalism we
elucidate the following: (i)We test the combined volume-stress ensemble by
comparing the statistical properties of jammed configurations obtained by
dynamics with those averaged over the ensemble of minima in the potential
energy landscape as a test of ergodicity. Agreement between both methods
supports the idea of "thermalization" at a given angoricity and compactivity.
(ii) A microcanonical ensemble analysis supports the idea of maximum entropy
principle for grains. (iii) The intensive variables describe the approach to
jamming through a series of scaling relations as A {\to} 0+ and X {\to} 0-. Due
to the force-volume coupling, the jamming transition can be probed
thermodynamically by a "jamming temperature" TJ comprised of contributions from
A and X. (iv) The thermodynamic framework reveals the order of the jamming
phase transition by showing the absence of critical fluctuations at jamming in
observables like pressure and volume. (v) Finally, we elaborate on a comparison
with relevant studies showing a breakdown of equiprobability of microstates.Comment: 22pages, 24 figure
Structure and properties of a novel fulleride Sm6C60
A novel fulleride Sm6C60 has been synthesized using high temperature solid
state reaction. The Rietveld refinement on high resolution synchrotron X-ray
powder diffraction data shows that Sm6C60 is isostructural with body-centered
cubic A6C60 (A=K, Ba). Raman spectrum of Sm6C60 is similar to that of Ba6C60,
and the frequencies of two Ag modes in Sm6C60 are nearly the same as that of
Ba6C60, suggesting that Sm is divalent and hybridization between C60 molecules
and the Sm atom could exist in Sm6C60. Resistivity measurement shows a weak
T-linear behavior above 180 K, the transport at low temperature is mainly
dominated by granular-metal theory.Comment: 9 pages, 3 figures, submitted to Phys. Rev. B (March 12, 1999
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