18,912 research outputs found
Network Flow Optimization for Restoration of Images
The network flow optimization approach is offered for restoration of
grayscale and color images corrupted by noise. The Ising models are used as a
statistical background of the proposed method. The new multiresolution network
flow minimum cut algorithm, which is especially efficient in identification of
the maximum a posteriori estimates of corrupted images, is presented. The
algorithm is able to compute the MAP estimates of large size images and can be
used in a concurrent mode. We also describe the efficient solutions of the
problem of integer minimization of two energy functions for the Ising models of
gray-scale and color images
Nonlinear Model of non-Debye Relaxation
We present a simple nonlinear relaxation equation which contains the Debye
equation as a particular case. The suggested relaxation equation results in
power-law decay of fluctuations. This equation contains a parameter defining
the frequency dependence of the dielectric permittivity similarly to the
well-known one-parameter phenomenological equations of Cole-Cole, Davidson-Cole
and Kohlrausch-Williams-Watts. Unlike these models, the obtained dielectric
permittivity (i) obeys to the Kramers-Kronig relation; (ii) has proper
behaviour at large frequency; (iii) its imaginary part, conductivity, shows a
power-law frequency dependence \sigma ~ \omega^n where n<1 corresponds to
empirical Jonscher's universal relaxation law while n>1 is also observed in
several experiments. The nonlinear equation proposed may be useful in various
fields of relaxation theory
Creating solitons by means of spin-orbit coupling
This mini-review collects theoretical results predicting the creation of
matter-wave solitons by the pseudo-spinor system of Gross-Pitaevskii equations
(GPEs) with the self-attractive cubic nonlinearity and linear
first-order-derivative terms accounting for the spin-orbit coupling (SOC). In
one dimension (1D), the so predicted bright solitons are similar to their
well-known counterparts supported by the GPE in the absence of SOC. Completely
novel results were recently obtained for 2D and 3D systems: SOC suppresses the
collapse instability of the multidimensional GPE, creating fully stable 2D
ground-state solitons and metastable 3D ones of two types: semi-vortices (SVs),
with vorticities m = 1 in one spin component and m = 0 in the other, and mixed
modes (MMs), with m = 0 and m = (+/-)1 present in both components. With the
Galilean invariance broken by SOC, moving solitons exist up to a certain
critical velocity, suffering delocalization above it. The newest result
predicts stable 2D "quantum droplets" of the MM type in the presence of the
Lee-Huang-Yang corrections to the GPE system, induced by quantum fluctuations
around the mean-field states, in the case when the inter-component attraction
dominates over the self-repulsion in each component.Comment: a slightly shortened version will be published as an invited
mini-review (perspective) in EP
Nucleon-Nucleon Scattering and Large N(c) QCD
Nucleon-nucleon scattering observables are discussed in the context of large
Nc QCD. As is well known, the baryon spectrum in the large Nc limit exhibits
contracted SU(2Nf) spin-flavor sym- metry. This symmetry can be used to derive
model-independent relations between proton-proton and proton-neutron total
cross sections. These relations are valid in the kinematic regime in which the
relative momentum of two nucleons is of order of Nc. In this semiclassical
regime the nucleon-nucleon scattering can be described in the time-dependent
mean field approximation. These model-independent results are compared to
experimental data for spin-independent and polarized total nucleon-nucleon
cross sections.Comment: 9 pages, 3 figures. Invited talk, Xth Quark Confinement and the
Hadron Spectrum, October 201
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