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A recent approach to generate a zero divergence velocity field by operating directly on the discretized Navier-Stokes equations is used to obtain the decoupling of the pressure from the velocity field. By following the methodology suggested by Amit, Hall, and Porsching the feasibility of treating… |
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In this paper we develop a direct quadrature method for solving Volterra-Fredholm integral equations on an unbounded spatial domain. These problems, when related to some important physical and biological phenomena, are characterized by kernels that present variable peaks along space. The method we… |
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Marine species reproduce and compete while being advected by turbulent flows. It is largely unknown, both theoretically and experimentally, how population dynamics and genetics are changed by the presence of fluid flows. Discrete agent-based simulations in continuous space allow for accurate… |
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The world lines of null particles admit arbitrary parametrizations. In the presence of a family of observers one may introduce along a null world line an extension of the so-called Cattaneo's relative standard time parameter (valid for massive particles) which plays a special role. Another… |
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In this paper we present an innovative and automatic procedure
which is used to extract the coastline from SAR (Synthetic Aperture
Radar) images by the level set model. This model consists in a PDE (Partial
Differential Equation) equation governing the evolution of a curve
corresponding to the zero… |
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In this paper we revisit the problem of performing a QZ step with a so-called "perfect shift", which is an
"exact" eigenvalue of a given regular pencil lambda B-A in unreduced Hessenberg-Triangular form. In exact
arithmetic, the QZ step moves that eigenvalue to the bottom of the pencil, while the… |
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One of the promising frontiers of bioengineering is the controlled release of a therapeutic drug from a vehicle across the skin (transdermal drug delivery). In order to study the complete process, a two-phase mathematical model describing the dynamics of a substance between two coupled media of… |
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In this paper, for the "critical case" with two delays, we establish two relations between any two solutions y(t) and y*(t) for the Volterra integral equation of non-convolution type
y(t)=f(t)+\int_{t-\tau}^{t-\delta}k(t,s)g(y(s))ds
and a solution z(t) of the first order differential equation
\dot… |
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A quadrature rule using Appell polynomials and generalizing both
the Euler-MacLaurin quadrature formula and a similar quadrature rule, obtained
in Bretti et al [15], which makes use of Euler (instead of Bernoulli)
numbers and even (instead of odd) derivatives of the given function at the
extrema of… |
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Results from direct numerical simulations (DNS) of particle relative dispersion in three-dimensional homogeneous and isotropic turbulence at Reynolds number Re?~300 are presented. We study point-like passive tracers and heavy particles, at Stokes number St=0.6,1 and 5. Particles are emitted from… |
