3,022 research outputs found
From Dumb Wireless Sensors to Smart Networks using Network Coding
The vision of wireless sensor networks is one of a smart collection of tiny,
dumb devices. These motes may be individually cheap, unintelligent, imprecise,
and unreliable. Yet they are able to derive strength from numbers, rendering
the whole to be strong, reliable and robust. Our approach is to adopt a
distributed and randomized mindset and rely on in network processing and
network coding. Our general abstraction is that nodes should act only locally
and independently, and the desired global behavior should arise as a collective
property of the network. We summarize our work and present how these ideas can
be applied for communication and storage in sensor networks.Comment: To be presented at the Inaugural Workshop of the Center for
Information Theory and Its Applications, University of California - San
Diego, La Jolla, CA, February 6 - 10, 200
Evolution of correlation strength in KxFe(2-y)Se2 superconductor doped with S
We report the evolution of thermal transport properties of iron-based
superconductor KFeSe with sulfur substitution at Se sites.
Sulfur doping suppresses the superconducting as well as the Seebeck
coefficient. The Seebeck coefficient of all crystals in the low temperature
range can be described very well by diffusive thermoelectric response model.
The zero-temperature extrapolated value of Seebeck coefficient divided by
temperature gradually decreases from to a very small
value 0.03 V/K where is completely suppressed. The normal
state electron Sommerfeld term () of specific heat also decreases
with the increase of sulfur content. The dcrease of and
reflects a suppression of the density of states at the Fermi energy, or a
change in the Fermi surface that would induce the suppression of correlation
strength.Comment: 5 Pages, 4 figures, 1 Table; submitted to Physical Review
NMR Characterization of Sulphur Substitution Effects in the K(x)Fe(2-y)Se(2-z)S(z) high Tc Superconductor
We present an NMR study of the effect of S substitution in the high Tc
superconductor K(x)Fe(2-y)Se(2-z)S(z) in a temperature range up to 250 K. We
present NMR Knight shift and nuclear spin-lattice relaxation rate 1/T1 data,
and compare our results to that of the non-substituted system K(x)Fe(2-y)Se(2).Comment: Typos fixed, figure replace
Thermoelectric studies of KxFe2-ySe2: weakly correlated superconductor
We report thermal transport measurement of KxFe2-ySe2 superconducting single
crystal. Significant peak anomaly in thermal conductivity is observed at nearly
TC/2 indicating a large phonon mean-free-path in the superconducting state. The
zero-temperature extrapolated thermoelectric power is smaller than the value in
typical strongly correlated superconductors, implying large normalized Fermi
temperature. In contrast to other iron superconductors, thermoelectric power in
our sample does not exhibit significant anomalies. These findings indicate that
KxFe2-ySe2 is a weakly or intermediately correlated superconductor without
significant Fermi surface nesting.Comment: Revised version, 5 pages, 5 figures, Will appear in Physical Review
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