13,003 research outputs found
Deep Learning for Single Image Super-Resolution: A Brief Review
Single image super-resolution (SISR) is a notoriously challenging ill-posed
problem, which aims to obtain a high-resolution (HR) output from one of its
low-resolution (LR) versions. To solve the SISR problem, recently powerful deep
learning algorithms have been employed and achieved the state-of-the-art
performance. In this survey, we review representative deep learning-based SISR
methods, and group them into two categories according to their major
contributions to two essential aspects of SISR: the exploration of efficient
neural network architectures for SISR, and the development of effective
optimization objectives for deep SISR learning. For each category, a baseline
is firstly established and several critical limitations of the baseline are
summarized. Then representative works on overcoming these limitations are
presented based on their original contents as well as our critical
understandings and analyses, and relevant comparisons are conducted from a
variety of perspectives. Finally we conclude this review with some vital
current challenges and future trends in SISR leveraging deep learning
algorithms.Comment: Accepted by IEEE Transactions on Multimedia (TMM
Isospin effect in the statistical sequential decay
Isospin effect of the statistical emission fragments from the equilibrated
source is investigated in the frame of statistical binary decay implemented
into GEMINI code, isoscaling behavior is observed and the dependences of
isoscaling parameters and on emission fragment size, source
size, source isospin asymmetry and excitation energies are studied. Results
show that and neither depends on light fragment size nor on
source size. A good linear dependence of and on the inverse of
temperature is manifested and the relationship of
and
from different
isospin asymmetry sources are satisfied. The symmetry energy coefficient
extracted from simulation results is 23 MeV which includes
both the volume and surface term contributions, of which the surface effect
seems to play a significant role in the symmetry energy.Comment: 8 pages, 8 figures; A new substantially modified version which has
been accepted by the Physical Review
The roles of deformation and orientation in heavy-ion collisions induced by light deformed nuclei at intermediate energy
The reaction dynamics of axisymmetric deformed Mg + Mg
collisions have been investigated systematically by an isospin-dependent
quantum molecular dynamics (IDQMD) model. It is found that different
deformations and orientations result in apparently different properties of
reaction dynamics. We revealed that some observables such as nuclear stopping
power (), multiplicity of fragments, and elliptic flow are very sensitive to
the initial deformations and orientations. There exists an eccentricity scaling
of elliptic flow in central body-body collisions with different deformations.
In addition, the tip-tip and body-body configurations turn out to be two
extreme cases in central reaction dynamical process.Comment: 5 pages, 7 figures, to appear in Physical Review C (Rapid
Communication
Dynamical and sequential decay effects on isoscaling and density dependence of the symmetry energy
The isoscaling properties of the primary and final products are studied via
isospin dependent quantum molecular dynamics
(IQMD) model and the followed sequential decay model GEMINI, respectively. It
is found that the isoscaling parameters of both primary and final
products keep no significant change for light fragments, but increases with the
mass for intermediate and heavy products. The dynamical effects on isoscaling
are exhibited by that value decreases a little with the evolution time
of the system, and opposite trend for the heavy products. The secondary decay
effects on isoscaling are reflected in the increasing of the value for
the final products which experiences secondary decay process.
Furthermore the density dependence of the symmetry energy has also been
explored, it is observed that in the low densities the symmetry energy
coefficient has the form of ,
where for both primary and final products, but
have different values for primary and final products. It is also suggested that
it might be more reasonable to describe the density dependence of the symmetry
energy coefficient by the
with , and constant
parameters.Comment: 10 pages, 10 figure
Hard photon flow and photon-photon correlation in intermediate energy heavy-ion collisions
Hard photons emitted from energetic heavy ion collisions are very interesting
since they do not experience nuclear interaction, and therefore they are useful
to explore properties of nuclear matter. We investigated hard photon production
and its properties in intermediate energy heavy-ion collisions with the help of
the Blotzmann-Uehling-Ulenbeck model. Two components of hard photons are
discussed: direct and thermal. The positive directed flow parameter and
negative elliptic flow parameter of direct photons are demonstrated and they
are anti-correlated to the flows of free protons. The dependencies of hard
photon production and anisotropic parameters on impact parameter, beam energy,
nuclear equation of state and symmetry energy are also discussed. Furthermore,
we investigated the two-photon momentum correlation function from which the
space-time structure information of the photon source could be extracted as
well as the two-photon azimuthal correlation which could provide another good
method to determine the elliptic flow parameter of direct hard photons.Comment: 13 pages, 18 figure
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