8,000 research outputs found
An Energy Driven Architecture for Wireless Sensor Networks
Most wireless sensor networks operate with very limited energy sources-their
batteries, and hence their usefulness in real life applications is severely
constrained. The challenging issues are how to optimize the use of their energy
or to harvest their own energy in order to lengthen their lives for wider
classes of application. Tackling these important issues requires a robust
architecture that takes into account the energy consumption level of functional
constituents and their interdependency. Without such architecture, it would be
difficult to formulate and optimize the overall energy consumption of a
wireless sensor network. Unlike most current researches that focus on a single
energy constituent of WSNs independent from and regardless of other
constituents, this paper presents an Energy Driven Architecture (EDA) as a new
architecture and indicates a novel approach for minimising the total energy
consumption of a WS
Statistical Analysis to Extract Effective Parameters on Overall Energy Consumption of Wireless Sensor Network (WSN)
In this paper, we use statistical tools to analysis dependency between
Wireless Sensor Network (WSN) parameters and overall Energy Consumption (EC).
Our approach has two main phases: profiling, and effective parameter
extraction. In former, a sensor network simulator is re-run 800 times with
different values for eight WSN parameters to profile consumed energy in nodes;
then in latter, three statistical analyses (p-value, linear and non-linear
correlation) are applied to the outcome of profiling phase to extract the most
effective parameters on WSN overall energy consumption.Comment: 5-pages. This paper has been accepted in PDCAT-2012 conference
(http://www.pdcat2012.org/
On surface completion and image inpainting by biharmonic functions: Numerical aspects
Numerical experiments with smooth surface extension and image inpainting
using harmonic and biharmonic functions are carried out. The boundary data used
for constructing biharmonic functions are the values of the Laplacian and
normal derivatives of the functions on the boundary. Finite difference schemes
for solving these harmonic functions are discussed in detail.Comment: Revised 21 July, 2017. Revised 12 January, 2018. To appear in
International Journal of Mathematics and Mathematical Science
Spinning Dust Emission: Effects of irregular grain shape, transient heating and comparison with WMAP results
Planck is expected to answer crucial questions on the early Universe, but it
also provides further understanding on anomalous microwave emission. Electric
dipole emission from spinning dust grains continues to be the favored
interpretation of anomalous microwave emission. In this paper, we present a
method to calculate the rotational emission from small grains of irregular
shape with moments of inertia . We show that a torque-free
rotating irregular grain with a given angular momentum radiates at multiple
frequency modes. The resulting spinning dust spectrum has peak frequency and
emissivity increasing with the degree of grain shape irregularity, which is
defined by . We discuss how the orientation of dipole moment
\bmu in body coordinates affects the spinning dust spectrum for different
regimes of internal thermal fluctuations. We show that the spinning dust
emissivity for the case of strong thermal fluctuations is less sensitive to the
orientation of \bmu than in the case of weak thermal fluctuations. We
calculate spinning dust spectra for a range of gas density and dipole moment.
The effect of compressible turbulence on spinning dust emission intensity is
investigated. We show that the emission intensity in a turbulent medium
increases by a factor from 1.2-1.4 relative to that in a uniform medium, as
sonic Mach number increases from 2-7. Finally, spinning dust parameters
are constrained by fitting our improved model to five-year {\it Wilkinson
Microwave Anisotropy Probe} cross-correlation foreground spectra, for both the
H-correlated and 100 m-correlated emission spectra.Comment: 24 pages, 17 figures, relation to molecular rotation spectra added,
accepted by Astrophysical Journa
Three-Loop Anomalous Dimension of the Heavy Quark Pair Production Current in Non-Relativistic QCD
The three-loop non-mixing contributions to the anomalous dimension of the
leading order quark pair production current in non-relativistic QCD are
computed. It is demonstrated that the renormalization procedure can only be
carried out consistently if the dynamics of both soft and the ultrasoft degrees
of freedom is present for all scales below the heavy quark mass, and if the
soft and ultrasoft renormalization scales are always correlated.Comment: 19 pages, revtex, 5 postscript figures include
Electroweak non-resonant NLO corrections to e+ e- -> W+ W- b bbar in the t tbar resonance region
We analyse subleading electroweak effects in the top anti-top resonance
production region in e+ e- collisions which arise due to the decay of the top
and anti-top quarks into the W+ W- b bbar final state. These are NLO
corrections adopting the non-relativistic power counting v ~ alpha_s ~
sqrt(alpha_EW). In contrast to the QCD corrections which have been calculated
(almost) up to NNNLO, the parametrically larger NLO electroweak contributions
have not been completely known so far, but are mandatory for the required
accuracy at a future linear collider. The missing parts of these NLO
contributions arise from matching coefficients of non-resonant production-decay
operators in unstable-particle effective theory which correspond to off-shell
top production and decay and other non-resonant irreducible background
processes to t tbar production. We consider the total cross section of the e+
e- -> W+ W- b bbar process and additionally implement cuts on the invariant
masses of the W+ b and W- bbar pairs.Comment: LaTeX, 33 pages, 6 figure
Supersymmetric Correction to Top Quark Pair Production near Threshold
We studied the leading supersymmetric contribution to top-antitop threshold
production using the NRQCD framework. The one-loop matching to the potential
and the Wilson coefficient of the leading production current were considered.
We point out that the leading correction to the potential is zero due to
SU(3)_c gauge invariance. This is true in general for any new physics that
enters above the electroweak scale. The shape of the top quark pair production
cross section is therefore almost unaffected near threshold, allowing a precise
determination of the top quark mass based on the Standard Model calculations.
The supersymmetric correction to the Wilson coefficient c_1 of the production
current decouples for heavy super particles. Its contribution is smaller than
the Standard Model next-to-next-leading-log results.Comment: 7 pages, 2 figure
Origin of the structural phase transition in Li7La3Zr2O12
Garnet-type Li7La3Zr2O12 (LLZO) is a solid electrolyte material with a
low-conductivity tetragonal and a high-conductivity cubic phase. Using
density-functional theory and variable cell shape molecular dynamics
simulations, we show that the tetragonal phase stability is dependent on a
simultaneous ordering of the Li ions on the Li sublattice and a
volume-preserving tetragonal distortion that relieves internal structural
strain. Supervalent doping introduces vacancies into the Li sublattice,
increasing the overall entropy and reducing the free energy gain from ordering,
eventually stabilizing the cubic phase. We show that the critical temperature
for cubic phase stability is lowered as Li vacancy concentration (dopant level)
is raised and that an activated hop of Li ions from one crystallographic site
to another always accompanies the transition. By identifying the relevant
mechanism and critical concentrations for achieving the high conductivity
phase, this work shows how targeted synthesis could be used to improve
electrolytic performance
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