10,940 research outputs found
Symbolic analysis for some planar piecewise linear maps
In this paper a class of linear maps on the 2-torus and some planar piecewise
isometries are discussed. For these discontinuous maps, by introducing codings
underlying the map operations, symbolic descriptions of the dynamics and
admissibility conditions for itineraries are given, and explicit expressions in
terms of the codings for periodic points are presented.Comment: 4 Figure
Image Aesthetics Assessment Using Composite Features from off-the-Shelf Deep Models
Deep convolutional neural networks have recently achieved great success on
image aesthetics assessment task. In this paper, we propose an efficient method
which takes the global, local and scene-aware information of images into
consideration and exploits the composite features extracted from corresponding
pretrained deep learning models to classify the derived features with support
vector machine. Contrary to popular methods that require fine-tuning or
training a new model from scratch, our training-free method directly takes the
deep features generated by off-the-shelf models for image classification and
scene recognition. Also, we analyzed the factors that could influence the
performance from two aspects: the architecture of the deep neural network and
the contribution of local and scene-aware information. It turns out that deep
residual network could produce more aesthetics-aware image representation and
composite features lead to the improvement of overall performance. Experiments
on common large-scale aesthetics assessment benchmarks demonstrate that our
method outperforms the state-of-the-art results in photo aesthetics assessment.Comment: Accepted by ICIP 201
Topological Strings and Quantum Spectral Problems
We consider certain quantum spectral problems appearing in the study of local
Calabi-Yau geometries. The quantum spectrum can be computed by the
Bohr-Sommerfeld quantization condition for a period integral. For the case of
small Planck constant, the periods are computed perturbatively by deformation
of the Omega background parameters in the Nekrasov-Shatashvili limit. We
compare the calculations with the results from the standard perturbation theory
for the quantum Hamiltonian. There have been proposals in the literature for
the non-perturbative contributions based on singularity cancellation with the
perturbative contributions. We compute the quantum spectrum numerically with
some high precisions for many cases of Planck constant. We find that there are
also some higher order non-singular non-perturbative contributions, which are
not captured by the singularity cancellation mechanism. We fix the first few
orders formulas of such corrections for some well known local Calabi-Yau
models.Comment: 47 pages, 3 figures. v2: journal version, typos correcte
Four-fermion interactions and the chiral symmetry breaking in an external magnetic field
We investigate the chiral symmetry and its spontaneous breaking at finite
temperature and in an external magnetic field with four-fermion interactions of
different channels. Quantum and thermal fluctuations are included within the
functional renormalization group approach, and properties of the set of flow
equations for different couplings, such as its fixed points, are discussed. It
is found that external parameters, e.g. the temperature and the external
magnetic field and so on, do not change the structure of the renormalization
group flows for the couplings. The flow strength is found to be significantly
dependent on the route and direction in the plane of couplings of different
channels. Therefore, the critical temperature for the chiral phase transition
shows a pronounced dependence on the direction as well. Given fixed initial
ultraviolet couplings, the critical temperature increases with the increasing
magnetic field, viz., the magnetic catalysis is observed with initial couplings
fixed.Comment: 8 pages, 4 figure
Potential Integral Equations in Electromagnetics
In this work, a new integral equation (IE) based formulation is proposed
using vector and scalar potentials for electromagnetic scattering. The new
integral equations feature decoupled vector and scalar potentials that satisfy
Lorentz gauge. The decoupling of the two potentials allows low-frequency
stability. The formulation presented also results in Fredholm integral
equations of second kind. The spectral properties of second kind integral
operators leads to a well-conditioned system.Comment: This paper was submitted to the proceedings of 2017 IEEE
International Symposium on Antennas and Propagation and USNC-URSI Radio
Science Meeting in January 201
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