102,752 research outputs found
Component-based Segmentation of words from handwritten Arabic text
Efficient preprocessing is very essential for automatic recognition of handwritten documents. In this paper, techniques on segmenting words in handwritten Arabic text are presented. Firstly, connected components (ccs) are extracted, and distances among different components are analyzed. The statistical distribution of this distance is then obtained to determine an optimal threshold for words segmentation. Meanwhile, an improved projection based method is also employed for baseline detection. The proposed method has been successfully tested on IFN/ENIT database consisting of 26459 Arabic words handwritten by 411 different writers, and the results were promising and very encouraging in more accurate detection of the baseline and segmentation of words for further recognition
Possible TeV Source Candidates In The Unidentified EGRET Sources
We study the -ray emission from the pulsar magnetosphere based on
outer gap models, and the TeV radiation from pulsar wind nebulae (PWNe) through
inverse Compton scattering using a one-zone model. We showed previously that
GeV radiation from the magnetosphere of mature pulsars with ages of years old can contribute to the high latitude unidentified EGRET
sources. We carry out Monte Carlo simulations of -ray pulsars in the
Galaxy and the Gould Belt, assuming the pulsar birth rate, initial position,
proper motion velocity, period, and magnetic field distribution and evolution
based on observational statistics. We select from the simulation a sample of
mature pulsars in the Galactic plane () and in the high
latitude () which could be detected by EGRET. The TeV flux from
the pulsar wind nebulae of our simulated sample through the inverse Compton
scattering by relativistic electrons on the microwave cosmic background and
synchrotron seed photons are calculated. The predicted fluxes are consistent
with the present observational constraints. We suggest that strong EGRET
sources can be potential TeV source candidates for present and future
ground-based TeV telescopes.Comment: Minor changes, MNRAS in pres
Effect of Diethylenetriamine and Triethylamine sensitization on the critical diameter of Nitromethane
In this work, the critical diameter for detonation was measured for Nitromethane (NM) sensitized with two different amines: Diethylenetriamine (DETA) and Triethylamine (TEA). The critical diameter in glass and polyvinylchloride tubes is found to decrease rapidly as the amount of sensitizer is increased, then increase past a critical amount of sensitizer. Thus the critical diameter reaches a minimum at a critical concentration of sensitizer. It was also found that the critical diameter is lower with DETA than with TEA
Solving the puzzle of an unconventional phase transition for a 2d dimerized quantum Heisenberg model
Motivated by the indication of a new critical theory for the spin-1/2
Heisenberg model with a spatially staggered anisotropy on the square lattice as
suggested in \cite{Wenzel08}, we re-investigate the phase transition of this
model induced by dimerization using first principle Monte Carlo simulations. We
focus on studying the finite-size scaling of and ,
where stands for the spatial box size used in the simulations and
with is the spin-stiffness in the -direction.
Remarkably, while we do observe a large correction to scaling for the
observable as proposed in \cite{Fritz11}, the data for
exhibit a good scaling behavior without any indication of a large
correction. As a consequence, we are able to obtain a numerical value for the
critical exponent which is consistent with the known O(3) result with
moderate computational effort. Specifically, the numerical value of we
determine by fitting the data points of to their expected scaling
form is given by , which agrees quantitatively with the most
accurate known Monte Carlo O(3) result . Finally, while we can
also obtain a result of from the observable second Binder ratio
which is consistent with , the uncertainty of calculated
from is more than twice as large as that of determined from
.Comment: 7 figures, 1 table; brief repor
Rotor Spectra, Berry Phases, and Monopole Fields: from Antiferromagnets to QCD
The order parameter of a finite system with a spontaneously broken continuous
global symmetry acts as a quantum mechanical rotor. Both antiferromagnets with
a spontaneously broken spin symmetry and massless QCD with a broken
chiral symmetry have rotor spectra when considered in
a finite volume. When an electron or hole is doped into an antiferromagnet or
when a nucleon is propagating through the QCD vacuum, a Berry phase arises from
a monopole field and the angular momentum of the rotor is quantized in
half-integer units.Comment: 4 page
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