54,513 research outputs found
A New Data Processing Inequality and Its Applications in Distributed Source and Channel Coding
In the distributed coding of correlated sources, the problem of
characterizing the joint probability distribution of a pair of random variables
satisfying an n-letter Markov chain arises. The exact solution of this problem
is intractable. In this paper, we seek a single-letter necessary condition for
this n-letter Markov chain. To this end, we propose a new data processing
inequality on a new measure of correlation by means of spectrum analysis. Based
on this new data processing inequality, we provide a single-letter necessary
condition for the required joint probability distribution. We apply our results
to two specific examples involving the distributed coding of correlated
sources: multi-terminal rate-distortion region and multiple access channel with
correlated sources, and propose new necessary conditions for these two
problems.Comment: 45 pages, 3 figures, submitted to IEEE Trans. Information Theor
Studies of hypersonic viscous flows over a blunt body at low Reynolds number
Viscous hypersonic shock layer over blunt bodies at low Reynolds numbe
Investigation of Micro Porosity Sintered wick in Vapor Chamber for Fan Less Design
Micro Porosity Sintered wick is made from metal injection molding processes,
which provides a wick density with micro scale. It can keep more than 53 %
working fluid inside the wick structure, and presents good pumping ability on
working fluid transmission by fine infiltrated effect. Capillary pumping
ability is the important factor in heat pipe design, and those general
applications on wick structure are manufactured with groove type or screen
type. Gravity affects capillary of these two types more than a sintered wick
structure does, and mass heat transfer through vaporized working fluid
determines the thermal performance of a vapor chamber. First of all, high
density of porous wick supports high transmission ability of working fluid. The
wick porosity is sintered in micro scale, which limits the bubble size while
working fluid vaporizing on vapor section. Maximum heat transfer capacity
increases dramatically as thermal resistance of wick decreases. This study on
permeability design of wick structure is 0.5 - 0.7, especially permeability (R)
= 0.5 can have the best performance, and its heat conductivity is 20 times to a
heat pipe with diameter (Phi) = 10mm. Test data of this vapor chamber shows
thermal performance increases over 33 %.Comment: Submitted on behalf of TIMA Editions
(http://irevues.inist.fr/tima-editions
Efimov Physics in Atom-Dimer Scattering of Lithium-6 Atoms
Lithium-6 atoms in the three lowest hyperfine states display universal
properties when the S-wave scattering length between each pair of states is
large. Recent experiments reported four pronounced features arising from Efimov
physics in the atom-dimer relaxation rate, namely two resonances and two local
minima. We use the universal effective field theory to calculate the atom-dimer
relaxation rate at zero temperature. Our results describe the four features
qualitatively and imply there is a hidden local minimum. In the vicinity of the
resonance at 685 G, we perform a finite temperature calculation which improves
the agreement of theory and experiment. We conclude that finite temperature
effects cannot be neglected in the analysis of the experimental data.Comment: 13 pages, 5 figures, final versio
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