2,360 research outputs found
Integration of statistics and food process engineering: Assessing the uncertainty of thermal processing and shelf-life estimations
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Photo-ionization of planetary winds: case study HD209458b
Close-in hot Jupiters are exposed to a tremendous photon flux that ionizes
the neutral escaping material from the planet leaving an observable imprint
that makes them an interesting laboratory for testing theoretical models. In
this work we present 3D hydrodynamic simulations with radiation transfer
calculations of a close-in exoplanet in a blow-off state. We calculate the
Ly- absorption and compare it with observations of HD 209458b an
previous simplified model results.Our results show that the hydrodynamic
interaction together with a proper calculation of the photoionization proccess
are able to reproduce the main features of the observed Ly- absorption,
in particular at the blue-shifted wings of the line. We found that the ionizing
stellar flux produce an almost linear effect on the amount of absorption in the
wake. Varying the planetary mass loss rate and the radiation flux, we were able
to reproduce the absorption observed at .Comment: 9 pages, 6 figure
Coupling Between Thermal Oscillations in the Surface of a Micro-Cylinder and Vortex Shedding
his article studies the coupling between prescribed thermal oscillations in the surface of a micro-cylinder and vortex shedding. We deal with the unsteady, laminar, compressible flow regime where the aerodynamics forces have a periodic behavior. It is shown that appropriate spatial and time-dependent temperature oscillations on the surface of the micro-cylinder create a resonance that controls the amplitude and frequency of both lift and drag coefficients. In practice, what we study is a mechanism to modulate the amplitude and frequency of mechanical loads of aerodynamics origin in a micro-structure by using surface temperature fluctuations as the control parameter
Origin of the bilateral structure of the supernova remnant G296.5+10
In this work, we have modelled the supernova remnant (SNR) G296.5+10, by means of 3D magnetohydrodynamics (MHD) simulations. This remnant belongs to the bilateral SNR group and has an additional striking feature: the rotation measure (RM) in its eastern and western parts are very different. In order to explain both the morphology observed in radio-continuum and the RM, we consider that the remnant expands into a medium shaped by the superposition of the magnetic field of the progenitor star with a constant Galactic magnetic field. We have also carried out a polarization study from our MHD results, obtaining synthetic maps of the linearly polarized intensity and the Stokes parameters. This study reveals that both the radio morphology and the reported RM for G296.5+10 can be explained if the quasi-parallel acceleration mechanism is taking place in the shock front of this remnant.Fil: Moranchel-Basurto, A.. Universidad Nacional Autónoma de México; MéxicoFil: Velazquez, P.. Universidad Nacional Autónoma de México; MéxicoFil: Giacani, Elsa Beatriz. Universidad de Buenos Aires. Facultad de Arquitectura y Urbanismo; Argentina. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Toledo Roy, J. C.. Universidad Nacional Autónoma de México; MéxicoFil: Schneiter, E.. Universidad Nacional Autónoma de México; MéxicoFil: De Colle, F.. Universidad Nacional Autónoma de México; MéxicoFil: Esquivel, A.. Universidad Nacional Autónoma de México; Méxic
Fluctuation geometry: A counterpart approach of inference geometry
Starting from an axiomatic perspective, \emph{fluctuation geometry} is
developed as a counterpart approach of inference geometry. This approach is
inspired on the existence of a notable analogy between the general theorems of
\emph{inference theory} and the the \emph{general fluctuation theorems}
associated with a parametric family of distribution functions
, which describes the behavior of a set of
\emph{continuous stochastic variables} driven by a set of control parameters
. In this approach, statistical properties are rephrased as purely
geometric notions derived from the \emph{Riemannian structure} on the manifold
of stochastic variables . Consequently, this theory
arises as an alternative framework for applying the powerful methods of
differential geometry for the statistical analysis. Fluctuation geometry has
direct implications on statistics and physics. This geometric approach inspires
a Riemannian reformulation of Einstein fluctuation theory as well as a
geometric redefinition of the information entropy for a continuous
distribution.Comment: Version submitted to J. Phys. A. 26 pages + 2 eps figure
Numerical Modeling of Eta Carinae Bipolar Outflows
In this paper, we present two-dimensional gas dynamic simulations of the
formation and evolution of the eta-Car bipolar outflows. Adopting the
interacting nonspherical winds model, we have carried out high-resolution
numerical simulations, which include explicitly computed time-dependent
radiative cooling, for different possible scenarios of the colliding winds. In
our simulations, we consider different degrees of non-spherical symmetry for
the pre-outburst wind and the great eruption of the 1840s presented by the
eta-Car wind. From these models, we obtain important differences in the shape
and kinematical properties of the Homunculus structure. In particular, we find
an appropriate combination of the wind parameters (that control the degree of
non-spherical symmetry) and obtain numerical experiments that best match both
the observed morphology and the expansion velocity of the eta-Car bipolar
shell. In addition, our numerical simulations show the formation of a bipolar
nebula embedded within the Homunculus (the little Homunculus) developed from a
secondary eruptive event suffered by the star in the 1890s, and also the
development of tenuous, high velocity ejections in the equatorial region that
result from the impact of the eruptive wind of the 1840s with the pre-outburst
wind and that could explain some of the high speed features observed in the
equatorial ejecta. The models were, however, unable to produce equatorial
ejections associated to the second eruptive event.Comment: 33 pages, 9 figures, accepted by the Astrophysical Journa
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