346 research outputs found
A DATA HIDING SCHEME BASED ON CHAOTIC MAP AND PIXEL PAIRS
Information security is one of the most common areas of study today. In the literature, there are many algorithms developed in the information security. The Least Significant Bit (LSB) method is the most known of these algorithms. LSB method is easy to apply however it is not effective on providing data privacy and robustness. In spite of all its disadvantages, LSB is the most frequently used algorithm in literature due to providing high visual quality. In this study, an effective data hiding scheme alternative to LSB, 2LSBs, 3LSBs and 4LSBs algorithms (known as xLSBs), is proposed. In this method, random numbers which are to be used as indices of pixels of the cover image are obtained from chaotic maps and data hiding process is applied on the values of these pixels by using modulo function. Calculated values are embedded in cover image as hidden data. Success of the proposed data hiding scheme is assessed by Peak Signal-to-Noise Ratio (PSNR), payload capacity and quality
Bohr-Sommerfeld Quantization of Space
We introduce semiclassical methods into the study of the volume spectrum in
loop gravity. The classical system behind a 4-valent spinnetwork node is a
Euclidean tetrahedron. We investigate the tetrahedral volume dynamics on phase
space and apply Bohr-Sommerfeld quantization to find the volume spectrum. The
analysis shows a remarkable quantitative agreement with the volume spectrum
computed in loop gravity. Moreover, it provides new geometrical insights into
the degeneracy of this spectrum and the maximum and minimum eigenvalues of the
volume on intertwiner space.Comment: 32 pages, 10 figure
Holographic Superconductors in a Cohesive Phase
We consider a four-dimensional N=2 gauged supergravity coupled to matter
fields. The model is obtained by a U(1) gauging of a charged hypermultiplet and
therefore it is suitable for the study of holographic superconductivity. The
potential has a topologically flat direction and the parameter running on this
"moduli space" labels the new superconducting black holes. Zero temperature
solutions are constructed and the phase diagram of the theory is studied. The
model has rich dynamics. The retrograde condensate is just a special case in
the new class of black holes. The calculation of the entanglement entropy makes
manifest the properties of a generic solution and the superconductor at zero
temperature is in a confined cohesive phase. The parameter running on the
topologically flat direction is a marginal coupling in the dual field theory.
We prove this statement by considering the way double trace deformations are
treated in the AdS/CFT correspondence. Finally, we comment on a possible
connection, in the context of gauge/gravity dualities, between the geometry of
the scalar manifold in N=2 supergravity models and the space of marginal
deformations of the dual field theory.Comment: 32 pages, 11 figures. Introduction rewritten and clarified, comments
and details on section 4 added, acknowledgements rectified. To appear in JHE
Information Hiding in Lossy Compression Gray Scale Image
[[abstract]]We propose an information hiding technique which based on pixels’ block. We used pixels contractive relation to hide the information that we want to embed. The characteristic of our method is that to use pixels contractive relation to assist lossy compression process in reducing the image size. There exists many hiding techniques, but most of the techniques cannot tolerate the destruction of lossy compression. Compression will speed up the transmission of the image with the hiding data.We achieve something others cannot do, to implement compression into the transmission of images in order to speed up the process. Besides, in our method it is easy to hide and extract the hiding data when implemented.We show that our method can extract the data efficiently and correctly, even with JPEG (Joint Picture Expert Group) compression. Our proposed technique tallies with the transmitted image on the Internet and it is a secure and efficient method.[[notice]]補正完畢[[incitationindex]]E
On the Large -charge Expansion in Superconformal Field Theories
In this note we study two point functions of Coulomb branch chiral ring
elements with large -charge, in quantum field theories with superconformal symmetry in four spacetime dimensions. Focusing on the case
of one-dimensional Coulomb branch, we use the effective-field-theoretic methods
of arXiv:1706.05743, to estimate the two-point function in the limit where the operator insertion On has large total
-charge . We show that
has a nontrivial but universal asymptotic expansion at large , of
the form where approaches a constant as
, and is an -independent constant
describing on the normalization of the operator relative to the effective
Abelian gauge coupling. The exponent is a positive number proportional
to the difference between the -anomaly coefficient of the underlying CFT and
that of the effective theory of the Coulomb branch. For Lagrangian SCFT, we
check our predictions against exact results from supersymmetric localization of
Baggio et. al. and Gerchkovitz et. al., and find precise agreement for the
logarithm , up to and including order
. We also give predictions for the growth of two-point
functions in all rank-one SCFT in the classification of Argyres et. al. In this
way, we show the large--charge expansion serves as a bridge from the world
of unbroken superconformal symmetry, OPE data, and bootstraps, to the world of
the low-energy dynamics of the moduli space of vacua.Comment: minor change
A survey of exemplar-based texture synthesis
Exemplar-based texture synthesis is the process of generating, from an input
sample, new texture images of arbitrary size and which are perceptually
equivalent to the sample. The two main approaches are statistics-based methods
and patch re-arrangement methods. In the first class, a texture is
characterized by a statistical signature; then, a random sampling conditioned
to this signature produces genuinely different texture images. The second class
boils down to a clever "copy-paste" procedure, which stitches together large
regions of the sample. Hybrid methods try to combine ideas from both approaches
to avoid their hurdles. The recent approaches using convolutional neural
networks fit to this classification, some being statistical and others
performing patch re-arrangement in the feature space. They produce impressive
synthesis on various kinds of textures. Nevertheless, we found that most real
textures are organized at multiple scales, with global structures revealed at
coarse scales and highly varying details at finer ones. Thus, when confronted
with large natural images of textures the results of state-of-the-art methods
degrade rapidly, and the problem of modeling them remains wide open.Comment: v2: Added comments and typos fixes. New section added to describe
FRAME. New method presented: CNNMR
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