摘要：
We have numerically investigated the propagation properties of ring Airy beams modeled by a fractional Schrödinger equation (FSE). Beam splitting is exhibited and clarified from the view of group delay. Compared with the case of the condition in free space, the focal intensity is greatly enhanced and presents a trend from increasing to decreasing with the decrement of the Lévy index, while the focal length largely increases; in addition, the parabolic trajectory is distorted with the Bessel pattern gradually disappearing. However, both the focal intensity and its length get decreased due to the absence of the initial phase of ring Airy beams; simultaneously, the size of the focal spot decreases for a larger Lévy index. The changes of focusing properties are clearly clarified. Moreover, without initial phase, the ratio of focal intensity under the Lévy index to the condition in free space is given to show the faster growth of focal intensity when the Lévy index is lower than 1.25; otherwise, the trend gets reversed. The autofocusing properties of ring Airy beams modeled by FSE can find applications in optical trapping and manipulation.
摘要：
We show that the group-velocity-led optical event horizon (OEH) in optical fibers provides a convenient way to actively control the propagation property of higher-order solitons by a comparatively weak dispersive wave (DW) pulse. It has been found numerically that clean soliton breakup, a process by which a second-order soliton completely splits into a pair of constituent solitons with vastly different power proportions after interacting with the weak DW pulse, will occur while external DWs become polychromatic. The temporal separation between both constituent solitons can be controlled by adjusting the power of the external DW. The more energetic main soliton is advanced/trailed in time depending on the selected frequency of input DW pulse. We have developed an analytic formalism describing the external acting-force (AF) perturbation. These results provide a fundamental explanation and physical scaling of optical pulse evolution in optical fibers and can find applications in improved supercontinuum sources.
摘要：
The aim of multi-focus image fusion is to create a synthetic all-in-focus image from several images each of which is obtained with different focus settings. However, if the resolution of source images is low, the fused images with traditional fusion method would be also in low-quality, which hinders further image analysis even the fused image is all-in-focus. This paper presents a novel joint multi-focus image fusion and super-resolution method via convolutional neural network (CNN). The first level network features of different source images are fused with the guidance of the local clarity calculated from the source images. The final high-resolution fused image is obtained with the reconstruction network filters which act like averaging filters. The experimental results demonstrate that the proposed approach can generate the fused images with better visual quality and acceptable computation efficiency as compared to other state-of-the-art works.
期刊：
IEEE Transactions On Electron Devices,2017年64(9):3654-3660 ISSN：0018-9383
通讯作者：
He, Hongyu
作者机构：
[He, Hongyu] Univ South China, Sch Elect Engn, Hengyang 421001, Peoples R China.;[He, Hongyu] Peking Univ, Shenzhen Grad Sch, Sch Elect & Comp Engn, Shenzhen 518005, Peoples R China.;[Liu, Yuan; Zheng, Xueren] South China Univ Technol, Sch Microelect, Guangzhou 510640, Guangdong, Peoples R China.;[Yan, Binghui] South China Agr Univ, Coll Elect Engn, Guangzhou 510642, Guangdong, Peoples R China.;[Lin, Xinnan] Peking Univ, Shenzhen Grad Sch, Sch Elect & Comp Engn, Shenzhen Key Lab Adv Electron Device & Integrat, Shenzhen 518005, Peoples R China.
通讯机构：
[He, Hongyu] U;[He, Hongyu] P;Univ South China, Sch Elect Engn, Hengyang 421001, Peoples R China.;Peking Univ, Shenzhen Grad Sch, Sch Elect & Comp Engn, Shenzhen 518005, Peoples R China.
关键词：
Analytical model;drain current;temperature characteristics;thin-film transistor (TFT);trap states
摘要：
Surface-potential-based drain current model is presented for amorphous InGaZnO thin-film transistors considering both exponential deep and tail trap states densities in the energy gap. The trap states densities are determined by the numerical calculation on the basis of the assumption that the trapped carrier concentration is much higher than the free carrier concentration. The analytical drain current model is developed consistent with the numerical calculation, and verified by the experimental data at different temperatures.
关键词：
Barrier coverage;Internet of Things (IoT);barrier gap;directional sensor networks;line-based deployment
摘要：
The barrier coverage of a wireless sensor network is an important surveillance application of Internet of Things. Barrier coverage guarantees that all intruders traversing the protected region are detected by a chain of connected sensors. However, when the sensors are randomly deployed, barrier gaps may occur due to deployment randomness or insufficient sensors. How to locate the barrier gaps and mend them is an important aspect in the network. In this paper, we study the barrier gap problem in weak barrier coverage and strong barrier coverage that consist of directional sensors, and the sensors are deployed by a line-based deployment strategy. A gap-finding algorithm is proposed to find subbarriers and barrier gaps. Two gap-mending algorithms are devised to mend barrier gaps in the network: One algorithm is a simple rotation algorithm that only rotates two critical sensors in two subbarriers to fix the gap, and the other algorithm is a chain-reaction rotation algorithm that rotates sensors in the subbarrier in a chain-reaction manner to mend the gap. We conduct extensive simulations to evaluate the performance of the proposed algorithms. Simulation results show that the proposed gap-mending algorithms can effectively fix barrier gaps and improve the probability of barrier success construction.
摘要：
Measuring rail profile in the presence of multiple degrees of freedom vibration is a very challenging task. This paper presents a novel method based on the local affine invariant feature descriptor to calibrate distorted profiles, which are obtained by traditional rail measurement system. It has three major modules: local affine invariant (LAI) feature descriptor, affine transformation estimation and parameters refinement. LAI feature descriptor is based on the affine geometry invariant and generated by calculating the proportions of different areas. Using the proposed LAI descriptor, we implement a three-stage profile calibration including matching, estimation, and refinement based on grouping and fast iterative closest point (FICP) algorithm. The performance of proposed LAI descriptor and calibrating method is tested by performing extensive experiments. The experimental results show that our LAI descriptor is highly descriptive and robust with respect to varying resolution and noise, and the LAI descriptor based calibration is effective and repeatable. (C) 2017 Elsevier Ltd. All rights reserved.
作者机构：
[Zhu, Weihua; He, Hongyu; Guo, Wei; Wang, Xinlin; Sheng, Jiabing; Chen, Zhiyong; Wang, XL; Yuan, Zhi] Univ South China, Sch Elect Engn, Hengyang 421001, Peoples R China.;[Wang, Xinlin] Univ South China, Sch Mech Engn, Hengyang 421001, Peoples R China.
通讯机构：
[Chen, ZY; Wang, XL; Wang, Xinlin] U;Univ South China, Sch Elect Engn, Hengyang 421001, Peoples R China.;Univ South China, Sch Mech Engn, Hengyang 421001, Peoples R China.
关键词：
Enhanced optical transmission;Finite-difference time-domain;Localized surface plasmon resonance;Subwavelength metallic film hole arrays;Unit structural features
摘要：
The relation between the enhanced optical transmission and the unit structural features is studied by changing the unit structural features. 3D finite-difference time-domain method is employed to study the enhanced optical transmission of periodic subwavelength circular-sharps shaped hole arrays in metallic films which are deposited on a quartz substrate. The influences of the unit structural features on the enhanced optical transmission are investigated. It is found that the enhanced optical transmission strongly depends on the unit structural edge sharp features: the sharp acuity, numbers, and distributions. The sharp acuity and numbers influence the enhanced optical transmission via localized surface plasmon resonance mode. The sharp distributions affect the enhanced optical transmission equaling to the effect of polarization properties. The results show that the surface plasmons strongly depend on unit structure edge sharp features. Changing the unit structural edge sharp features, the properties of the enhanced optical transmission can be tailored. This paper provides theoretical support for building the various functions of new plasmonic devices.
摘要：
The delay time dependence of photoelectron spectra and state populations of three-level ladder K2 molecule is investigated by pump-probe pulses via time-dependent wave packet approach. The periodical motion of the wave packet with oscillating period 500 fs results in the periodical variation of photoelectron spectra. The photoelectron spectra show Autler-Townes double splitting at zero delay time, and no splitting at positive delay time. The periodical change of state populations with delay time can be ascribed to the coupling effect between the two pulses. It is found that the selectivity of the state populations may be attained by regulating the delay time. The results can provide some important basis for realizing the optical control of molecules experimentally.
作者机构：
[Lu, Xingqiang] Univ South China, Sch Nucl Sci & Technol, Hengyang 421001, Peoples R China.;[Ma, Zhiwei] Zhejiang Univ, Inst Fus Theory & Simulat, Hangzhou 310027, Zhejiang, Peoples R China.;[Guo, Wei] Univ South China, Sch Elect Engn, Hengyang 421001, Peoples R China.
通讯机构：
[Ma, Zhiwei] Z;Zhejiang Univ, Inst Fus Theory & Simulat, Hangzhou 310027, Zhejiang, Peoples R China.
摘要：
Behavior of the fast earthward flow near the braking region in the magnetotail during a substorm is investigated using the Hall MHD simulation. The results indicate that the highspeed earthward plasma flow is associated with fast reconnection in the middle tail. The fast flow is mainly confined in the range -1.5RE > z > 1.5RE. In the region of -15RE >x >-9RE, due to intermittent magnetic reconnection, the earthward flow exhibits a fluctuating property, i.e., the flow is localized in space and is bursty in time. The pile-up of the magnetic flux and plasma in the near-Earth region leads to formation of the fast-flow braking region or dipolarization front. After colliding into the fast-flow braking region, a part of the Earth flow bounces back, and leads to an intermittent tailward flow in the near-Earth magnetotail.
摘要：
The dependence of the wave packet process of three-level ladder K2 molecules on pulse width was investigated via time-dependent wave packet method, and was firstly quantified. There is no Autler-Townes splitting in the photoelectron spectrum with weaker pump intensity or shorter pulse width. The oscillation period of wave packet increases and the oscillation amplitude decreases with increasing pulse width. The pulse width affects Rabi oscillation, which results in the periodical change of the populations of the electronic state. Quantifying its effect on the population of the excited state shows that the change frequency varies with increasing pump intensity. The results illustrates that the needed population in electronic state of interested can be obtained by controlling pulse width, which provide some important basis for light manipulation of molecular processes experimentally.
摘要：
In this paper, an efficient approximate sparse representation (SR) algorithm with multi-selection strategy is used to solve the image fusion problem. We have shown that the approximate SR is effective for image fusion even if the sparse coefficients are not the sparsest ones possible. A multi-selection strategy is used to accelerate the process of generating the approximate sparse coefficients which are used to guide the fusion of image patches. The relative parameters are also investigated experimentally to further reduce the computational time. The proposed method is compared with some state-of-the-art image fusion approaches on several pairs of multi-source images. The experimental results exhibit that the proposed method is able to yield superior fusion results with less consumption time.
