798 research outputs found
Logarithmic mathematical morphology: a new framework adaptive to illumination changes
A new set of mathematical morphology (MM) operators adaptive to illumination
changes caused by variation of exposure time or light intensity is defined
thanks to the Logarithmic Image Processing (LIP) model. This model based on the
physics of acquisition is consistent with human vision. The fundamental
operators, the logarithmic-dilation and the logarithmic-erosion, are defined
with the LIP-addition of a structuring function. The combination of these two
adjunct operators gives morphological filters, namely the logarithmic-opening
and closing, useful for pattern recognition. The mathematical relation existing
between ``classical'' dilation and erosion and their logarithmic-versions is
established facilitating their implementation. Results on simulated and real
images show that logarithmic-MM is more efficient on low-contrasted information
than ``classical'' MM
Визнання арбітражної угоди недійсною
У статті розглянуто питання недійсності арбітражної угоди, визначені етапи, на яких виникає дане питання, досліджені підстави для визнання арбітражної угоди недійсною.В статье рассмотрен вопрос недействительности арбитражного соглашения, определены этапы, на которых возникает данный вопрос, исследованы основания для признания арбитражного соглашения недействительным.This article analyses the issue of invalidity of the arbitration agreement, marks out the stages on which this matter arises, examines the grounds for invalidity of the arbitration agreement
Reconstruction of three-dimensional porous media using generative adversarial neural networks
To evaluate the variability of multi-phase flow properties of porous media at
the pore scale, it is necessary to acquire a number of representative samples
of the void-solid structure. While modern x-ray computer tomography has made it
possible to extract three-dimensional images of the pore space, assessment of
the variability in the inherent material properties is often experimentally not
feasible. We present a novel method to reconstruct the solid-void structure of
porous media by applying a generative neural network that allows an implicit
description of the probability distribution represented by three-dimensional
image datasets. We show, by using an adversarial learning approach for neural
networks, that this method of unsupervised learning is able to generate
representative samples of porous media that honor their statistics. We
successfully compare measures of pore morphology, such as the Euler
characteristic, two-point statistics and directional single-phase permeability
of synthetic realizations with the calculated properties of a bead pack, Berea
sandstone, and Ketton limestone. Results show that GANs can be used to
reconstruct high-resolution three-dimensional images of porous media at
different scales that are representative of the morphology of the images used
to train the neural network. The fully convolutional nature of the trained
neural network allows the generation of large samples while maintaining
computational efficiency. Compared to classical stochastic methods of image
reconstruction, the implicit representation of the learned data distribution
can be stored and reused to generate multiple realizations of the pore
structure very rapidly.Comment: 21 pages, 20 figure
Density of States for a Specified Correlation Function and the Energy Landscape
The degeneracy of two-phase disordered microstructures consistent with a
specified correlation function is analyzed by mapping it to a ground-state
degeneracy. We determine for the first time the associated density of states
via a Monte Carlo algorithm. Our results are described in terms of the
roughness of the energy landscape, defined on a hypercubic configuration space.
The use of a Hamming distance in this space enables us to define a roughness
metric, which is calculated from the correlation function alone and related
quantitatively to the structural degeneracy. This relation is validated for a
wide variety of disordered systems.Comment: Accepted for publication in Physical Review Letter
Life and Death at the Edge of a Windy Cliff
The survival probability of a particle diffusing in the two dimensional
domain near a ``windy cliff'' at is investigated. The particle dies
upon reaching the edge of the cliff. In addition to diffusion, the particle is
influenced by a steady ``wind shear'' with velocity , \ie, no average bias either toward or away from the cliff.
For this semi-infinite system, the particle survival probability decays with
time as , compared to in the absence of wind. Scaling
descriptions are developed to elucidate this behavior, as well as the survival
probability within a semi-infinite strip of finite width with particle
absorption at . The behavior in the strip geometry can be described in
terms of Taylor diffusion, an approach which accounts for the crossover to the
decay when the width of the strip diverges. Supporting numerical
simulations of our analytical results are presented.Comment: 13 pages, plain TeX, 5 figures available upon request to SR
(submitted to J. Stat. Phys.
The A+B -> 0 annihilation reaction in a quenched random velocity field
Using field-theoretic renormalization group methods the long-time behaviour
of the A+B -> 0 annihilation reaction with equal initial densities n_A(0) =
n_B(0) = n_0 in a quenched random velocity field is studied. At every point (x,
y) of a d-dimensional system the velocity v is parallel or antiparallel to the
x-axis and depends on the coordinates perpendicular to the flow. Assuming that
v(y) have zero mean and short-range correlations in the y-direction we show
that the densities decay asymptotically as n(t) ~ A n_0^(1/2) t^(-(d+3)/8) for
d<3. The universal amplitude A is calculated at first order in \epsilon = 3-d.Comment: 19 pages, LaTeX using IOP-macros, 5 eps-figures. It is shown that the
amplitude of the density is universal, i.e. independent of the reaction rat
Spinoza
"Spinoza", second edition.
Encyclopedia entry for the Springer Encyclopedia of EM Phil and the Sciences, ed. D. Jalobeanu and C. T. Wolfe
Invisibility in billiards
The question of invisibility for bodies with mirror surface is studied in the
framework of geometrical optics. We construct bodies that are invisible/have
zero resistance in two mutually orthogonal directions, and prove that there do
not exist bodies which are invisible/have zero resistance in all possible
directions of incidence
First Passage Time in a Two-Layer System
As a first step in the first passage problem for passive tracer in stratified
porous media, we consider the case of a two-dimensional system consisting of
two layers with different convection velocities. Using a lattice generating
function formalism and a variety of analytic and numerical techniques, we
calculate the asymptotic behavior of the first passage time probability
distribution. We show analytically that the asymptotic distribution is a simple
exponential in time for any choice of the velocities. The decay constant is
given in terms of the largest eigenvalue of an operator related to a half-space
Green's function. For the anti-symmetric case of opposite velocities in the
layers, we show that the decay constant for system length crosses over from
behavior in diffusive limit to behavior in the convective
regime, where the crossover length is given in terms of the velocities.
We also have formulated a general self-consistency relation, from which we have
developed a recursive approach which is useful for studying the short time
behavior.Comment: LaTeX, 28 pages, 7 figures not include
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