5,258 research outputs found
Anisotropic thermal expansion and thermomechanic properties of monolayer -Te
Recently, -Te (atomically 2D tellurium) with rectangular crystal
structure has been synthesized successfully on highly oriented pyrolytic
graphite substrates by using molecular beam epitaxy. It has been found
possessing remarkable properties such as ultralow lattice thermal conductivity
and high thermoelectric efficiency. Based on the first-principles calculations,
we study the thermal expansion and thermomechanic properties of the
experimental phase monolayer -Te, using quasiharmonic approach. It is
found -Te shows large positive thermal expansion at elevated
temperature, while the linear thermal expansion coefficient is negative along a
direction at very low temperature. The linear thermal expansion coefficient
along b direction is 4.9*10 K at 500 K, which is considerably
large in 2D materials. -Te exhibits strong in-plane anisotropy,
including thermal expansion, 2D elastic moduli and Poisson's ratios. However,
the elastic moduli, Poisson's ratios and the in-plane anisotropy are weakened
with increasing temperature, and the variations are dominated by the
generalized mode Gr\"{u}neisen parameters.Comment: 25 pages, 7 figures, 14 formula
Synthesizing and Controlling Helical Indirect Exchange Interactions at Nonequilibrium
We study the nonequilibrium effects of spin and/or electric currents on the
helical indirect exchange interactions of local spins that embedded in general
open electronic systems. Especially, besides the synthesized anisotropic
Heisenberg interactions, we find that the synthetic helical indirect exchange
interactions possess two parts: antisymmetric (Dzyaloshinskii-Moriya
interaction) and symmetric (Kaplan-Shekhtman-Entin-Wohlman-Aharony
interaction), which are all formulated in terms of Keldysh nonequilibrium
Green's functions. The presence of either spin-orbit coupling or spin polarized
currents alone is able to synthesize and control the antisymmetric
Dzyaloshinskii-Moriya exchange interactions, as the same direction as spin
splitting. However, the appearance of symmetric
Kaplan-Shekhtman-Entin-Wohlman-Aharony interactions requires both, i.e., the
spin-orbit coupling and spin polarized currents with different splitting
directions. Our results show the detailed scheme of controlling the sign,
magnitude, and direction of indirect Dzyaloshinskii-Moriya vectors and
Kaplan-Shekhtman-Entin-Wohlman-Aharony interactions at nonequilibrium in open
quantum devices.Comment: 8 pages, 7 figure
Next-to-leading order QCD corrections to production at 14 TeV LHC
Since the precise study of Higgs gauge couplings is important to test the
Standard Model (SM), we calculate the complete next-to-leading order QCD(NLO
QCD) correction to the production in the SM at 14 TeV LHC.
Our results show that the NLO QCD correction can enhance the leading-order
cross section of by 45%, when = 125.3 GeV. We also
study the dependence of the LO and NLO corrected cross sections on the
renormalization and factorization scale . Besides, due to the unbalance of
parton distribution functions, we investigate the charge asymmetry of
in the production of , which can reach 32.94% for
at 14 TeV LHC.Comment: discussions added, accepted by Physics Letters
Entanglement entropy and fidelity susceptibility in the one-dimensional spin-1 XXZ chains with alternating single-site anisotropy
We study the fidelity susceptibility in an antiferromagnetic spin-1 XXZ chain
numerically. By using the density-matrix renormalization group method, the
effects of the alternating single-site anisotropy on fidelity
susceptibility are investigated. Its relation with the quantum phase transition
is analyzed. It is found that the quantum phase transition from the Haldane
spin liquid to periodic N\'{e}el spin solid can be well characterized by the
fidelity. Finite size scaling of fidelity susceptibility shows a power-law
divergence at criticality, which indicates the quantum phase transition is of
second order. The results are confirmed by the second derivative of the
ground-state energy. We also study the relationship between the entanglement
entropy, the Schmidt gap and quantum phase transitions. Conclusions drawn from
these quantum information observables agree well with each other.Comment: 5 pages, 6 figures, accepted by J. Phys.: Condens. Matte
Revisiting Associated Production of 125 GeV Higgs Boson with a Photon at a Higgs Factory
Considering the constraints from the flavor physics, precision electroweak
measurements, Higgs data and dark matter detections, we scan over the parameter
space of the MSSM and calculate the cross section of in
the allowed parameter space. Since the loop-induced gauge couplings
and can simultaneously contribute to the process
, we find the cross section can be sizably enhanced by a
light stau, maximally 1.47(1.38) times larger than the SM prediction at
GeV. So with the high luminosity, the measurement of
may be used to test the anomalous gauge couplings
and in the MSSM at a Higgs Factory.Comment: discussions and references added, version accepted by J. Phys.
Gated Multi-layer Convolutional Feature Extraction Network for Robust Pedestrian Detection
Pedestrian detection methods have been significantly improved with the
development of deep convolutional neural networks. Nevertheless, robustly
detecting pedestrians with a large variant on sizes and with occlusions remains
a challenging problem. In this paper, we propose a gated multi-layer
convolutional feature extraction method which can adaptively generate
discriminative features for candidate pedestrian regions. The proposed gated
feature extraction framework consists of squeeze units, gate units and a
concatenation layer which perform feature dimension squeezing, feature elements
manipulation and convolutional features combination from multiple CNN layers,
respectively. We proposed two different gate models which can manipulate the
regional feature maps in a channel-wise selection manner and a spatial-wise
selection manner, respectively. Experiments on the challenging CityPersons
dataset demonstrate the effectiveness of the proposed method, especially on
detecting those small-size and occluded pedestrians
Physical States and BRST Operators for Higher-spin Strings
In this paper, we mainly investigate the
system, in which the matter and the Liouville subsystems generate
and algebras respectively. We first give a brief discussion of the
physical states for corresponding stings. The lower states are given by
freezing the spin-2 and spin- currents. Then, introducing two pairs of
ghost-like fields, we give the realizations of algebras. Based on
these linear realizations, BRST operators for algebras are obtained.
Finally, we construct new BRST charges of Liouville system for
strings at the specific values of central charges : for
algebra, for algebra and
for algebra, at which the corresponding algebras are
singular.Comment: 18 pages, 2 tables, no figure
An End-to-End Compression Framework Based on Convolutional Neural Networks
Deep learning, e.g., convolutional neural networks (CNNs), has achieved great
success in image processing and computer vision especially in high level vision
applications such as recognition and understanding. However, it is rarely used
to solve low-level vision problems such as image compression studied in this
paper. Here, we move forward a step and propose a novel compression framework
based on CNNs. To achieve high-quality image compression at low bit rates, two
CNNs are seamlessly integrated into an end-to-end compression framework. The
first CNN, named compact convolutional neural network (ComCNN), learns an
optimal compact representation from an input image, which preserves the
structural information and is then encoded using an image codec (e.g., JPEG,
JPEG2000 or BPG). The second CNN, named reconstruction convolutional neural
network (RecCNN), is used to reconstruct the decoded image with high-quality in
the decoding end. To make two CNNs effectively collaborate, we develop a
unified end-to-end learning algorithm to simultaneously learn ComCNN and
RecCNN, which facilitates the accurate reconstruction of the decoded image
using RecCNN. Such a design also makes the proposed compression framework
compatible with existing image coding standards. Experimental results validate
that the proposed compression framework greatly outperforms several compression
frameworks that use existing image coding standards with state-of-the-art
deblocking or denoising post-processing methods.Comment: Submitted to IEEE Transactions on Circuits and Systems for Video
Technolog
Real-Time Robot Localization, Vision, and Speech Recognition on Nvidia Jetson TX1
Robotics systems are complex, often consisted of basic services including
SLAM for localization and mapping, Convolution Neural Networks for scene
understanding, and Speech Recognition for user interaction, etc. Meanwhile,
robots are mobile and usually have tight energy constraints, integrating these
services onto an embedded platform with around 10 W of power consumption is
critical to the proliferation of mobile robots. In this paper, we present a
case study on integrating real-time localization, vision, and speech
recognition services on a mobile SoC, Nvidia Jetson TX1, within about 10 W of
power envelope. In addition, we explore whether offloading some of the services
to cloud platform can lead to further energy efficiency while meeting the
real-time requirementsComment: 12 pages, 8 figure
High Thermoelectric Performance in Two-Dimensional Tellurium: An Ab Initio Study
In 2016, bulk tellurium was experimentally observed as a remarkable
thermoelectric material. Recently, two-dimensional (2D) tellurium, called
tellurene, has been synthesized and has exhibited unexpected electronic
properties compared with the 2D MoS. They have also been fabricated into
air-stable and high efficient field-effect transistors. There are two stable 2D
tellurene phases. One (-Te) has been confirmed with an ultralow lattice
thermal conductivity (). However, the study of the transport
properties of the other more stable phase, -Te, is still lacking. Here,
we report the thermoelectric performance and phonon properties of -Te
using Boltzmann transport theory and first principle calculations. A maximum ZT
value of 0.83 is achieved under reasonable hole concentration, suggesting that
the monolayer -Te is a potential competitor in the thermoelectric
field.Comment: 14 pages, 5 figure
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