22,816 research outputs found
On the difference between updating the mixing matrix and updating the separation matrix
Raw data for our paper: "Interrelated chemical-microstructural-nanomechanical variations in the structural units of the cuttlebone of Sepia officinalis" DOI: 10.1063/1.499320
Sparsity and adaptivity for the blind separation of partially correlated sources
Blind source separation (BSS) is a very popular technique to analyze
multichannel data. In this context, the data are modeled as the linear
combination of sources to be retrieved. For that purpose, standard BSS methods
all rely on some discrimination principle, whether it is statistical
independence or morphological diversity, to distinguish between the sources.
However, dealing with real-world data reveals that such assumptions are rarely
valid in practice: the signals of interest are more likely partially
correlated, which generally hampers the performances of standard BSS methods.
In this article, we introduce a novel sparsity-enforcing BSS method coined
Adaptive Morphological Component Analysis (AMCA), which is designed to retrieve
sparse and partially correlated sources. More precisely, it makes profit of an
adaptive re-weighting scheme to favor/penalize samples based on their level of
correlation. Extensive numerical experiments have been carried out which show
that the proposed method is robust to the partial correlation of sources while
standard BSS techniques fail. The AMCA algorithm is evaluated in the field of
astrophysics for the separation of physical components from microwave data.Comment: submitted to IEEE Transactions on signal processin
CVABS: Moving Object Segmentation with Common Vector Approach for Videos
Background modelling is a fundamental step for several real-time computer
vision applications that requires security systems and monitoring. An accurate
background model helps detecting activity of moving objects in the video. In
this work, we have developed a new subspace based background modelling
algorithm using the concept of Common Vector Approach with Gram-Schmidt
orthogonalization. Once the background model that involves the common
characteristic of different views corresponding to the same scene is acquired,
a smart foreground detection and background updating procedure is applied based
on dynamic control parameters. A variety of experiments is conducted on
different problem types related to dynamic backgrounds. Several types of
metrics are utilized as objective measures and the obtained visual results are
judged subjectively. It was observed that the proposed method stands
successfully for all problem types reported on CDNet2014 dataset by updating
the background frames with a self-learning feedback mechanism.Comment: 12 Pages, 4 Figures, 1 Tabl
Fast Mixing for the Low Temperature 2D Ising Model Through Irreversible Parallel Dynamics
We study tunneling and mixing time for a non-reversible probabilistic cellular automaton. With a suitable choice of the parameters, we first show that the stationary distribution is close in total variation to a low temperature Ising model. Then we prove that both the mixing time and the time to exit a metastable state grow polynomially in the size of the system, while this growth is exponential in reversible dynamics. In this model, non-reversibility, parallel updatings and a suitable choice of boundary conditions combine to produce an efficient dynamical stability
Fast mixing for the low temperature 2d Ising model through irreversible parallel dynamics
We study metastability and mixing time for a non-reversible probabilistic
cellular automaton. With a suitable choice of the parameters, we first show
that the stationary distribution is close in total variation to a low
temperature Ising model. Then we prove that both the mixing time and the time
to exit a metastable state grow polynomially in the size of the system, while
this growth is exponential in reversible dynamics. In this model,
non-reversibility, parallel updatings and a suitable choice of boundary
conditions combine to produce an efficient dynamical stability
Ultraviolet filtering of lattice configurations and applications to Monte Carlo dynamics
We present a detailed study of a filtering method based upon Dirac
quasi-zero-modes in the adjoint representation. The procedure induces no
distortions on configurations which are solutions of the euclidean classical
equations of motion. On the other hand, it is very effective in reducing the
short-wavelength stochastic noise present in Monte Carlo generated
configurations. After testing the performance of the method in various
situations, we apply it successfully to study the effect of Monte Carlo
dynamics on topological structures like instantons.Comment: 39 pages, 15 figure
The supersymmetric Ward identities on the lattice
Supersymmetric (SUSY) Ward identities are considered for the N=1 SU(2) SUSY
Yang Mills theory discretized on the lattice with Wilson fermions (gluinos).
They are used in order to compute non-perturbatively a subtracted gluino mass
and the mixing coefficient of the SUSY current. The computations were performed
at gauge coupling =2.3 and hopping parameter =0.1925, 0.194,
0.1955 using the two-step multi-bosonic dynamical-fermion algorithm. Our
results are consistent with a scenario where the Ward identities are satisfied
up to O(a) effects. The vanishing of the gluino mass occurs at a value of the
hopping parameter which is not fully consistent with the estimate based on the
chiral phase transition. This suggests that, although SUSY restoration appears
to occur close to the continuum limit of the lattice theory, the results are
still affected by significant systematic effects.Comment: 34 pages, 7 figures. Typo corrected, last sentence reformulated,
reference added. To appear in Eur. Phys. J.
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