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 1/21/2 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 $r_{01}$ and $r_{10}$ 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 $\delta_{\rm ov}$ between approximately 1.2 and 1.6 can reproduce the observed ratios $r_{01}$ and $r_{10}$ of KIC 2837475. The ratios $r_{01}$ and $r_{10}$ 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 $\delta_{\rm ov}$. Thus the ratio distributions are more sensitive to $\delta_{\rm ov}$ 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 $M=1.490\pm0.018$ $M_{\odot}$, $R=1.67\pm0.01$ $R_{\odot}$, age $=2.8\pm0.4$ Gyr, and $1.2\lesssim$ $\delta_{\rm ov}$ $\lesssim1.6$ for KIC 2837475.Comment: Accepted for publication in MNRAS. 9 pages, 10 figures. The ratios $r_{01}$ and $r_{10}$ 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