17,496 research outputs found
Band Modulation for Silicene and Graphene Quantum Dots: A First-Principles Calculation
The band modulation of the silicene and graphene quantum dots is investigated
by a first-principles method. This study includes the ordinary silicene and
graphene quantum dots and the embedded quantum dots in the hydrogenated
silicene and graphene. The shapes and sizes of quantum dots are recognized as
important factors for the electronic properties. We studied several types of
quantum dots: triangular, parallelogram, rectangular, hexagonal dots. It
demonstrates the energy gap of the quantum dot can be tuned by the dot size,
the larger of the dot the smaller the energy gap. Moreover, the shapes affect
the magnetism of the quantum dots. The triangular dot exhibits as magnetic
semiconductor; the parallelogram dot shows antiferromagnetic characteristics;
while the hexagonal dot is non-magnetic. Control the size and shape of a
silicene or graphene quantum dot can manipulate its magnetism and electronic
properties.Comment: 3 pages, 5 figure
KL property of exponent for zero-norm composite quadratic functions
This paper is concerned with a class of zero-norm regularized and constrained
composite quadratic optimization problems, which has important applications in
the fields such as sparse eigenvalue problems, sparse portfolio problems, and
nonnegative matrix factorizations. For this class of nonconvex and nonsmooth
problems, we establish the KL property of exponent 1/2 of its objective
function under a suitable assumption, and provide some examples to illustrate
that the assumption holds
Small world yields optimal public goods in presence of both altruistic and selfish cooperators
Empirical studies have shown that individuals' behaviors are largely
influenced by social conformity, including punishment. However, a
coevolutionary theoretical framework that takes into account effects of
conformity on individuals' punishment behaviors has not been put forward yet.
Herein we propose a coevolutionary game model to extend the theory of
cooperation with conformity in spatial public goods game by considering pool
punishment, as well as two converse feedback modes of conformity that strongly
affect cooperators' punishment behaviors. We focus on how different parameters
and spatial structures govern evolutionary dynamics on three different kinds of
networks by employing mean-field analysis based on replicator dynamics and
Monte Carlo simulations. On regular lattices, defectors are overall extincted
since cooperators, especially selfish cooperators, have great evolutionary
advantages due to strong network reciprocity, and at the same time the number
of altruistic cooperators decays. Conversely, abundant shortcuts in regular
random networks lead to the prevalence of altruistic cooperators, but
cooperators suffer from free-riding behaviors of defectors. Of particular
interest, we find that small-world topology can simultaneously help cooperators
successfully outperform defectors by means of strong network reciprocity, and
enable rich contacting opportunities with defectors to facilitate the expansion
of altruistic cooperators. Therefore, we clarify that small world is the
optimal topology subject to the dominance of altruistic cooperators.Comment: 12 pages 14 figure
Holographic complexity of the disk subregion in (2+1)-dimensional gapped systems
Using the volume of the space enclosed by the Ryu-Takayanagi (RT) surface, we
study the complexity of the disk-shape subregion (with radius R) in various
(2+1)-dimensional gapped systems with gravity dual. These systems include a
class of toy models with singular IR and the bottom-up models for quantum
chromodynamics and fractional quantum Hall effects. Two main results are: i) in
the large-R expansion of the complexity, the R-linear term is always absent,
similar to the absence of topological entanglement entropy; ii) when the
entanglement entropy exhibits the classic `swallowtail' phase transition, the
complexity is sensitive but reacts differently.Comment: 30 pages, 7 figures, revised version accepted for publication in PR
Large magnetoelectric effect in mechanically mediated structure of TbFe2, Pb(Zr,Ti)O3 and nonmagnetic flakes
Magnetoelectric (ME) effect has been studied in a structure of a
magnetostrictive TbFe2 alloy, two piezoelectric Pb(Zr,Ti)O3 (PZT) ceramics, and
two nonmagnetic flakes. The ME coupling originates from the
magnetic-mechanical-electric transform of the magnetostrictive effect in TbFe2
and the piezoelectric effect in PZT by end bonding, instead of interface
bonding. Large ME coefficients of 10.5 and 9.9 Vcm-1Oe-1 were obtained at the
first planar acoustic and third bending resonance frequencies, which are larger
than that of conventional layered TbFe2/PZT composites. The results show that
the large ME coupling can be achieved without interface coupling.Comment: 3 pages, 4 figures, 18 conference
An End-to-End Mispronunciation Detection System for L2 English Speech Leveraging Novel Anti-Phone Modeling
Mispronunciation detection and diagnosis (MDD) is a core component of
computer-assisted pronunciation training (CAPT). Most of the existing MDD
approaches focus on dealing with categorical errors (viz. one canonical phone
is substituted by another one, aside from those mispronunciations caused by
deletions or insertions). However, accurate detection and diagnosis of
non-categorial or distortion errors (viz. approximating L2 phones with L1
(first-language) phones, or erroneous pronunciations in between) still seems
out of reach. In view of this, we propose to conduct MDD with a novel end-
to-end automatic speech recognition (E2E-based ASR) approach. In particular, we
expand the original L2 phone set with their corresponding anti-phone set,
making the E2E-based MDD approach have a better capability to take in both
categorical and non-categorial mispronunciations, aiming to provide better
mispronunciation detection and diagnosis feedback. Furthermore, a novel
transfer-learning paradigm is devised to obtain the initial model estimate of
the E2E-based MDD system without resource to any phonological rules. Extensive
sets of experimental results on the L2-ARCTIC dataset show that our best system
can outperform the existing E2E baseline system and pronunciation scoring based
method (GOP) in terms of the F1-score, by 11.05% and 27.71%, respectively.Comment: Accepted by Interspeech202
The damage inflicted by a computer virus: A new estimation method
This paper addressed the issue of estimating the damage caused by a computer
virus. First, an individual-level delayed SIR model capturing the spreading
process of a digital virus is derived. Second, the damage inflicted by the
virus is modeled as the sum of the economic losses and the cost for developing
the antivirus. Next, the impact of different factors, including the delay and
the network structure, on the damage is explored by means of computer
simulations. Thereby some measures of reducing the damage of a virus are
recommended. To our knowledge, this is the first time the antivirus-developing
cost is taken into account when estimating the damage of a virus
Field-free spin-orbit-torque switching of perpendicular magnetization aided by uniaxial shape anisotropy
It has been demonstrated that the switching of perpendicular magnetization
can be achieved with spin orbit torque (SOT) at an ultrafast speed and low
energy consumption. However, to make the switching deterministic, an
undesirable magnetic field or unconventional device geometry is required to
break the structure inverse symmetry. Here we propose a novel scheme for
SOT-induced field-free deterministic switching of perpendicular magnetization.
The proposed scheme can be implemented in a simple magnetic tunnel junction
(MTJ) /heavy-metal system, without the need of complicated device structure.
The perpendicular-anisotropy MTJ is patterned into elliptical shape and
misaligned with the axis of the heavy metal, so that the uniaxial shape
anisotropy aids the magnetization switching. Furthermore, unlike the
conventional switching scheme where the switched final magnetization state is
dependent on the direction of the applied current, in our scheme the bipolar
switching is implemented by choosing different current paths, which offers a
new freedom for developing novel spintronics memories or logic devices. Through
the macrospin simulation, we show that a wide operation window of the applied
current pulse can be obtained in the proposed scheme. The precise control of
pulse amplitude or pulse duration is not required. The influences of key
parameters such as damping constant and field-like torque strength are
discussed as well.Comment: 6 pages, 5 figure
Generic Multiview Visual Tracking
Recent progresses in visual tracking have greatly improved the tracking
performance. However, challenges such as occlusion and view change remain
obstacles in real world deployment. A natural solution to these challenges is
to use multiple cameras with multiview inputs, though existing systems are
mostly limited to specific targets (e.g. human), static cameras, and/or camera
calibration. To break through these limitations, we propose a generic multiview
tracking (GMT) framework that allows camera movement, while requiring neither
specific object model nor camera calibration. A key innovation in our framework
is a cross-camera trajectory prediction network (TPN), which implicitly and
dynamically encodes camera geometric relations, and hence addresses missing
target issues such as occlusion. Moreover, during tracking, we assemble
information across different cameras to dynamically update a novel
collaborative correlation filter (CCF), which is shared among cameras to
achieve robustness against view change. The two components are integrated into
a correlation filter tracking framework, where the features are trained offline
using existing single view tracking datasets. For evaluation, we first
contribute a new generic multiview tracking dataset (GMTD) with careful
annotations, and then run experiments on GMTD and the PETS2009 datasets. On
both datasets, the proposed GMT algorithm shows clear advantages over
state-of-the-art ones
Asteroseismic analysis of Kepler target KIC 2837475
The ratios and of small to large separations of KIC 2837475
primarily exhibit an increase behavior in the observed frequency range. The
calculations indicate that only the models with overshooting parameter
between approximately 1.2 and 1.6 can reproduce the observed
ratios and of KIC 2837475. The ratios and
of the frequency separations of p-modes with inner turning points that are
located in the overshooting region of convective core can exhibit an increase
behavior. The frequencies of the modes that can reach the overshooting region
decrease with the increase in . Thus the ratio distributions
are more sensitive to than to other parameters. The increase
behavior of the KIC 2837475 ratios results from a direct effect of the
overshooting of convective core. The characteristic of the ratios provides a
strict constraint on stellar models. Observational constraints point to a star
with , , age
Gyr, and for KIC
2837475.Comment: Accepted for publication in MNRAS. 9 pages, 10 figures. The ratios
and of KIC 2837475 exhibit an interesting behavior, which
can be directly reproduced by stellar models. Adiabatic oscillation
frequencies of the models can be downloaded from
http://pan.baidu.com/s/1c00LPwk. arXiv admin note: text overlap with
arXiv:1508.0095
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