6,950 research outputs found
Antiferromagnetism, -wave and chiral -wave superconductivity in a Kagome lattice with possible application to -graphenes
We investigate the electronic instabilities in a Kagome lattice with Rashba
spin-orbital coupling by the unbiased singular-mode functional renormalization
group. At the parent -filling, the normal state is a quantum spin Hall
system. Since the bottom of the conduction band is near the van Hove
singularity, the electron-doped system is highly susceptible to competing
orders upon electron interactions. The topological nature of the parent system
enriches the complexity and novelty of such orders. We find -type
intra-unitcell antiferromagnetic order, -wave superconductivity and chiral
-wave superconductivity with increasing electron doping above the van Hove
point. In both types of superconducting phases, there is a mixture of
comparable spin singlet and triplet components because of the Rashba coupling.
The chiral -wave superconducting state is characterized by a Chern number
, supporting a branch of Weyl fermion states on each edge. The model bares
close relevance to the so-called -graphenes proposed recently.Comment: 6 pages, 5 color figure
Superconductivity in SrRuO thin film under biaxial strain
Motivated by the success of experimental manipulation of the band structure
through biaxial strain in SrRuO thin film grown on a mismatched
substrate, we investigate theoretically the effects of biaxial strain on the
electronic instabilities, such as superconductivity (SC) and spin density wave
(SDW), by functional renormalization group. According to the experiment, the
positive strain (from lattice expansion) causes charge transfer to the
-band and consequently Lifshitz reconstruction of the Fermi surface.
Our theoretical calculations show that within a limited range of positive
strain a p-wave superconducting order is realized. However, as the strain is
increased further the system develops into the SDW state well before the
Lifshitz transition is reached. We also consider the effect of negative strains
(from lattice constriction). As the strain increases, there is a transition
from p-wave SC state to nodal s-wave SC state. The theoretical results are
discussed in comparison to experiment and can be checked by further
experiments.Comment: 9 pages, 5 color figure
Efficient Multi-level Correlating for Visual Tracking
Correlation filter (CF) based tracking algorithms have demonstrated favorable
performance recently. Nevertheless, the top performance trackers always employ
complicated optimization methods which constraint their real-time applications.
How to accelerate the tracking speed while retaining the tracking accuracy is a
significant issue. In this paper, we propose a multi-level CF-based tracking
approach named MLCFT which further explores the potential capacity of CF with
two-stage detection: primal detection and oriented re-detection. The cascaded
detection scheme is simple but competent to prevent model drift and accelerate
the speed. An effective fusion method based on relative entropy is introduced
to combine the complementary features extracted from deep and shallow layers of
convolutional neural networks (CNN). Moreover, a novel online model update
strategy is utilized in our tracker, which enhances the tracking performance
further. Experimental results demonstrate that our proposed approach
outperforms the most state-of-the-art trackers while tracking at speed of
exceeded 16 frames per second on challenging benchmarks.Comment: Accepted by ACCV'201
Improved Thermometer from Intermediate Mass Fragments in Heavy-Ion Collisions with Isobaric Yield Ratio Difference
\item[Background] Temperature is an important parameter in studying many
important questions in heavy-ion collisions. A thermometer based on the
isobaric yield ratio (IYR) has been proposed [Ma \textit{et al.}, Phys. Rev. C
\textbf{86}, 054611 (2012) and Ma \textit{et al.}, \textit{ibid.}, Phys. Rev. C
\textbf{88}, 014609 (2013)]. \item[Purpose] An improved thermometer ()
is proposed based on the difference between IYRs. obtained from
isobars in different reactions will be compared. \item[Methods] The yields of
three isobars are employed in . The residual free energy of the three
isobars are replaced by that of the binding energy. No secondary decay
modification for odd fragment is used in . \item[Results] The
measured fragment yields in the 140 MeV Ca + Be
(Ta) and Ni + Be (Ta), the 1 GeV Xe + Pb, and the Sn + Sn reactions have been
analyzed to obtain from IMFs. from most of the fragments in
the Ca and Ni reactions is in the range of 0.6 MeV 3.5 MeV. from most of the fragments in the Xe and
Sn reactions is in the range of 0.5 MeV 2.5 MeV,
while the range is 0.5 MeV 4 MeV from most of the fragments in
the Xe reaction. In general, for most of the fragments in the
Ca and Ni reactions are very similar (except in the very
neutron-rich fragments), and from IMFs in the Xe and
Sn reactions is also similar. A slightly dependence of on
is found. \item[Conclusions] Using the binding energy of the nucleus,
can be obtained without the knowledge of the free energies of
fragments. In the investigated reactions, from most of the IMFs is
low.Comment: 7 pages, 9 figures. To appear on Physical Review
Dependence of elliptic flow on transverse momentum in 200 GeV Au-Au and 2.76 TeV Pb-Pb collisions
We investigate the dependence of elliptic flows on transverse momentum
for charged hadrons produced in nucleus-nucleus collisions at high energy
by using a multi-source ideal gas model which includes the interaction
contribution of the emission sources. Our calculated results are approximately
in agreement with the experimental data over a wider range from the STAR
and ALICE Collaborations. It is found that the expansion factor increases
linearly with the impact parameter from most central (0-5%) to mid-peripheral
(35-40%) collisions.Comment: 8 pages, 4 figure
Toric Difference Variety
In this paper, the concept of toric difference varieties is defined and four
equivalent descriptions for toric difference varieties are presented in terms
of difference rational parametrization, difference coordinate rings, toric
difference ideals, and group actions by difference tori. Connections between
toric difference varieties and affine N[x]-semimodules are established by
proving the correspondence between the irreducible invariant difference
subvarieties and the faces of the N[x]-submodules and the orbit-face
correspondence. Finally, an algorithm is given to decide whether a binomial
difference ideal represented by a Z[x]-lattice defines a toric difference
variety
A Scaling Phenomenon in Shannon Information Uncertainty Difference of fragments in Heavy-ion Collisions
The Shannon information-entropy uncertainty (in brief as "information
uncertainty") is used to analyze the fragments in the measured 140 MeV
Ca + Be and Ni + Be reactions. A scaling
phenomenon is found in the information-uncertainty difference of fragments
between the reactions. The scaling phenomenon is explained in a manner of
canonical ensemble theory, and is reproduced in the simulated reactions by the
antisymmetric molecular dynamics (AMD) and AMD + GEMINI models. The probes
based on information uncertainty, requiring no equilibrium state of reaction,
can be used in the non-equilibrium system, and bridge the results of the static
thermodynamics models and the evolving dynamical transport models.Comment: 11 pages, 7 figure
Optimal Size for Maximal Energy Efficiency in Information Processing of Biological Systems Due to Bistability
Energy efficiency is closely related to the evolution of biological systems
and is important to their information processing. In this paper, we calculated
the excitation probability of a simple model of a bistable biological unit in
response to pulsatile inputs, and its spontaneous excitation rate due to noise
perturbation. Then we analytically calculated the mutual information, energy
cost, and energy efficiency of an array of these bistable units. We found that
the optimal number of units could maximize this array's energy efficiency in
encoding pulse inputs, which depends on the fixed energy cost. We conclude that
demand for energy efficiency in biological systems may strongly influence the
size of these systems under the pressure of natural selection.Comment: 5 pages, 3 figures, submitted to Chinese Physics Lette
Generalized two-dimensional linear discriminant analysis with regularization
Recent advances show that two-dimensional linear discriminant analysis
(2DLDA) is a successful matrix based dimensionality reduction method. However,
2DLDA may encounter the singularity issue theoretically and the sensitivity to
outliers. In this paper, a generalized Lp-norm 2DLDA framework with
regularization for an arbitrary is proposed, named G2DLDA. There are
mainly two contributions of G2DLDA: one is G2DLDA model uses an arbitrary
Lp-norm to measure the between-class and within-class scatter, and hence a
proper can be selected to achieve the robustness. The other one is that by
introducing an extra regularization term, G2DLDA achieves better generalization
performance, and solves the singularity problem. In addition, G2DLDA can be
solved through a series of convex problems with equality constraint, and it has
closed solution for each single problem. Its convergence can be guaranteed
theoretically when . Preliminary experimental results on three
contaminated human face databases show the effectiveness of the proposed
G2DLDA
Designing an Inertia Actuator with a Fast Rotating Gyro inside an Egg-shaped Robot
In this paper, we describe features of two new robot prototypes that are
actuated by an actively controlled gyro (flywheel, symmetric rotor) inside a
hollow sphere that is located in the middle of the robots. No external
actuators are used. The outside structure of the robots and the gyro are
connected by a gimbal, which is similar in structure to a control moment
gyroscope in spacecrafts. The joints of the gimbal can be actuated. In this
way, the orientation of axis for the gyro in relation to the egg can be
changed. Since the inertia of the fast rotating gyro is large in relation to
the outside structure, a relative rotation of the axis against the outside
structure results in a motion of the egg by inertia principle. In this way, we
can use this principle for controlling the robot to move forward and turn
around. The robots are shaped as spheroidal ellipsoids so they resemble eggs.
So far, we have built and tested two robot prototypes
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