32,725 research outputs found
Monte Carlo Simulations of Some Dynamical Aspects of Drop Formation
In this work we present some results from computer simulations of dynamical
aspects of drop formation in a leaky faucet. Our results, which agree very well
with the experiments, suggest that only a few elements, at the microscopic
level, would be necessary to describe the most important features of the
system. We were able to set all parameters of the model in terms of real ones.
This is an additional advantage with respect to previous theoretical works.Comment: 7 pages (Latex), 6 figures (PS) Accepted to publication in Int. J.
Mod. Phys. C Source Codes at http://www.if.uff.br/~arlim
Efeito de diferentes sistemas de aquecimento no desempenho de leitoes.
bitstream/item/59001/1/CUsersPiazzonDocuments122.pd
Memory in the Black-Scholes model
The evolution in time of European options is usually studied using
the Black-Scholes formula. This formula is obtained from the equivalence between
the Black-Scholes equation and a heat equation. The solution of the last equation
presents infinite speed of propagation which induces the same property for European
options. In this paper we study integro-differential equations which can be used to
describe the evolution of European options and which is established replacing the
heat equation by a delayed heat equation.Center for Mathematics of University of Coimbra; Project PTDC/MAT/74548/200
Comparison of solar radio and EUV synoptic limb charts during the present solar maximum
The present solar cycle is particular in many aspects: it had a delayed
rising phase, it is the weakest of the last 100 years, and it presents two
peaks separated by more than one year. To understand the impact of these
characteristics on the solar chromosphere and coronal dynamics, images from a
wide wavelength range are needed. In this work we use the 17~GHz radio
continuum, formed in the upper chromosphere and the EUV lines 304 and
171~{\AA}, that come from the transition region (He II) and the corona (Fe IX,
X), respectively. We analyze daily images at 304 and 171~{\AA} obtained by the
Atmospheric Imaging Assembly (AIA). The 17~GHz maps were obtained by the
Nobeyama Radioheliograph (NoRH). To construct synoptic limb charts, we
calculated the mean emission of delimited limb areas with 100" wide and angular
separation of . At the equatorial region, the results show an
hemispheric asymmetry of the solar activity. The northern hemisphere dominance
is coincident with the first sunspot number peak, whereas the second peak
occurs concurrently with the increase in the activity at the south. The polar
emission reflects the presence of coronal holes at both EUV wavelengths,
moreover, the 17~GHz polar brightenings can be associated with the coronal
holes. Until 2013, both EUV coronal holes and radio polar brightenings were
more predominant at the south pole. Since then they have not been apparent in
the north, but thus appear in the beginning of 2015 in the south as observed in
the synoptic charts. This work strengthens the association between coronal
holes and the 17~GHz polar brightenings as it is evident in the synoptic limb
charts, in agreement with previous case study papers. The enhancement of the
radio brightness in coronal holes is explained by the presence of bright
patches closely associated with the presence of intense unipolar magnetic
fields.Comment: 6 pages, 5 figures. Acccepted for publication in Astronomy &
Astrophysic
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