期刊：
Physica E-Low-Dimensional Systems & Nanostructures,2022年143:115350 ISSN：1386-9477
通讯作者：
L.Z. Sun
作者机构：
[Zhou, P.; Sun, L. Z.; Li, W. Q.] Xiangtan Univ, Sch Mat Sci & Engn, Hunan Prov Key Lab Thin Film Mat & Devices, Xiangtan 411105, Peoples R China.;[Tan, R.] Hengyang Normal Univ, Coll Phys & Elect Engn, Hengyang 421002, Peoples R China.
通讯机构：
[L.Z. Sun] H;Hunan Provincial Key Laboratory of Thin Film Materials and Devices, School of Material Sciences and Engineering, Xiangtan University, Xiangtan 411105, China
关键词：
Two-dimensional carbon-nitrogen;Dirac semimetal;Topological phase;Density functional theory
摘要：
Two-dimensional (2D) carbon-nitrogen materials have aroused a lot of interest due to their amazing performance and possible uses. However, only a few of them have been discovered to have semimetallic properties. Based on first-principles calculations, we predict a unique 2D Dirac semimetal C(5)N(4 )with stable thermodynamics, dynamics, and mechanics. The Dirac cones in the system are rightly located at the Fermi level, and they are mostly contributed by the pz orbitals of C and N atoms. By examining the irreducible representations of related Bloch states, we discover that they are protected by the sigma(g)(x) and C-2z symmetries. In addition, we establish a k.p model and an 18-band tight-binding (TB) model to investigate the formation and properties of Dirac points. Furthermore, we find that the Dirac points are robust to external strains. Finally, we propose a method for synthesizing this material. The C5N4 monolayer is a novel potential material for high-performance electronic devices in the future.
摘要：
In multiferroic materials, microscopic magnetic and electric textures are correlated with each other via magnetoelectric (ME) coupling. Thus, a ferroelectric (FE) dipolar skyrmionic crystal (or lattice so as to be abbreviated as SL for convenience) is expected to be induced once a ferromagnetic (FM) SL is stabilized in these materials. Using a quantum computational method, we find in simulations that the two sorts of topological crystals can indeed be generated simultaneously in a two-dimensional multiferroic monolayer; each FE skyrmion is a ferroelectric dipolar complex formed around one FM skyrmion; the topological charges of these FE skyrmions are quantized to be integers, half integers and multiples of certain fractional values; the topological charge density of every FE SL also forms periodic pattern; and a perpendicularly applied electric field is able to alter the wavelengths of the FM and FE SLs, elevate their formation temperatures, and destroy them below the original critical temperatures.
关键词：
compact torus (CT);circuit modelling;nonlinear regression analysis (NRA);point Model
摘要：
Compact torus（CT） injection is one of the most promising methods for the central fuelling of next-generation reactor-grade fusion devices due to its high density, high velocity, and selfcontained magnetised structure. A newly compact torus injector（CTI） device in Keda Torus e Xperiment（KTX）, named KTX-CTI, was successfully developed and tested at the University of Science and Technology in China. In this study, first, we briefly introduce the basic principles and structure of KTX-CTI, and then, present an accurate circuit model that relies on nonlinear regression analysis（NRA） for studying the current waveform of the formation region. The current waveform, displacement, and velocity of CT plasma in the acceleration region are calculated using this NRA-based one-dimensional point model. The model results were in good agreement with the experiments. The next-step upgrading reference scheme of the KTX-CTI device is preliminarily investigated using this NRA-based point model. This research can provide insights for the development of experiments and future upgrades of the device.
通讯机构：
[Liemao Cao] C;[Yee Sin Ang] S;College of Physics and Electronic Engineering, Hengyang Normal University , Hengyang 421002, China<&wdkj&>Science, Mathematics and Technology (SMT), Singapore University of Technology and Design (SUTD) , 8 Somapah Road, Singapore 487372
期刊：
Journal of Electronic Materials,2022年51(9):5142-5149 ISSN：0361-5235
通讯作者：
Xue, W.
作者机构：
School of Physics and Optoelectronics Engineering, Xiangtan University, Hunan, 411105, China;School of Physics and Electrical Sciences, Hunan Institute of Science and Technology, Yueyang, 414006, China;Institution of Condensed Physics, College of Physics and Electronic Engineering, Hengyang Normal University, Hengyang, 421002, China
通讯机构：
School of Physics and Optoelectronics Engineering, Xiangtan University, Hunan, China
作者：
Liu, Hong Bo;Liu, Guan Nan;Sun, Ai Ping;Xiao, Zheng Yao;Li, Xin Xia
期刊：
Journal of the Korean Physical Society,2022年81(5):397-402 ISSN：0374-4884
通讯作者：
Xin Xia Li
作者机构：
[Li, Xin Xia; Liu, Guan Nan; Xiao, Zheng Yao; Liu, Hong Bo] Univ South China, Dept Nucl Phys, Hengyang 421001, Peoples R China.;[Liu, Hong Bo] Hengyang Normal Univ, Sch Phys & Elect Engn, Hengyang 421008, Peoples R China.;[Sun, Ai Ping] Southwestern Inst Phys, POB 432, Chengdu 610041, Sichuan, Peoples R China.
通讯机构：
[Xin Xia Li ] D;Department of Nuclear Physics, University of South China, Hengyang, People’s Republic of China
关键词：
Helicon wave;Off-axis current drive;HL-2M;AORSA
摘要：
Helicon waves have been proposed for efficient off-axis current drive in high-performance tokamaks. The HL-2M tokamak will be operated with high plasma beta approaching to
$$\beta _{N}\sim 4.0\%$$
, which provides a good platform to apply helicon wave system in the machine. Based on the helicon wave dispersion relation, effects of electron Landau damping and transit time magnetic pumping on wave absorption are analyzed according to the HL-2M plasma, and then, an optimized scheme of helicon wave parameter is proposed. The evolution of helicon wave electric field and produced current drive are calculated by the AORSA full-wave code. It shows that current drive efficiency of 100 kA/MW can be generally received in the machine. Moreover, the AORSA results are actively benchmarked with the ray-tracing code, and the results show a good consistency. Finally, the numerical convergence and the consumption of computation resources on grid point numbers in AORSA code are discussed.
作者机构：
[Lu, Wangjun; Zhai, Cuilu] Hunan Inst Engn, Dept Maths & Phys, Xiangtan 411104, Peoples R China.;[Liu, Yan; Lu, Wangjun; Yuan, Jibing; Tang, Shiqing; Song, Yaju] Hengyang Normal Univ, Coll Phys & Elect Engn, Hengyang 421002, Peoples R China.;[Lu, Wangjun] Zhejiang Univ, Zhejiang Inst Modern Phys, Dept Phys, Hangzhou 310027, Peoples R China.;[Li, Songsong] Nanchang Normal Univ, Coll Phys & Elect Informat, Nanchang 330032, Peoples R China.
通讯机构：
[Shiqing Tang] C;College of Physics and Electronic Engineering, Hengyang Normal University, Hengyang 421002, China<&wdkj&>Author to whom correspondence should be addressed.
摘要：
In this paper, we investigate the effect of the Dicke quantum phase transition on the speed of evolution of the system dynamics. At the phase transition point, the symmetry associated with the system parity operator begins to break down. By comparing the magnitudes of the two types of quantum speed limit times, we find that the quantum speed limit time of the system is described by one of the quantum speed limit times, whether in the normal or superradiant phase. We find that, in the normal phase, the strength of the coupling between the optical field and the atoms has little effect on the dynamical evolution speed of the system. However, in the superradiant phase, a stronger atom–photon coupling strength can accelerate the system dynamics’ evolution. Finally, we investigate the effect of the entanglement of the initial state of the system on the speed of evolution of the system dynamics. We find that in the normal phase, the entanglement of the initial state of the system has almost no effect on the system dynamics’ evolution speed. However, in the superradiant phase, larger entanglement of the system can accelerate the evolution of the system dynamics. Furthermore, we verify the above conclusions by the actual evolution of the system.
摘要：
Many multi-objective optimization problems in reality are dynamic, requiring the optimization algorithm to quickly track the moving optima after the environment changes. Therefore, response strategies are often used in dynamic multi-objective algorithms to find Pareto optimal. In this paper, we propose a hybrid prediction strategy based on the classification of decision variables, which consists of three steps. After detecting the environment change, the first step is to analyze the influence of each decision variable on individual convergence and distribution in the new environment. The second step is to adopt different prediction methods for different decision variables. Finally, adaptive selection is applied to the solution set generated in the first and second steps, and solutions with good convergence and diversity are selected to make the initial population more adaptable to the new environment. The prediction strategy can help the solution set converge while maintaining its diversity. The experimental results and performance show that the proposed algorithm is capable of significantly improving the dynamic optimization performance compared with five state-of-the-art evolutionary algorithms.
通讯机构：
[Gang Ouyang] K;Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control of Ministry of Education, Key Laboratory for Matter Microstructure and Function of Hunan Province, School of Physics and Electronics, Hunan Normal University, Changsha, 410081 China
关键词：
C-60;MoS2;electron (hole) transfer rate;light absorptance;mixed-dimensional van der Waals heterostructures;power conversion efficiencies
摘要：
Constructing 0D-2D mixed-dimensional van der Waals (MvdW) heterostructures is an effective strategy to improve photovoltaic properties of photovoltaic devices. However, addressing the underlying mechanism on the role of array periodicity of 0D and thickness of 2D components on the photovoltaic properties at the atomic-level still remains challenging. Herein, the interfacial charge transfer and photovoltaic conversion mechanism in C-60/MoS2 0D-2D MvdWs based on the atomic-bond-relaxation consideration, Marcus theory, modified-detailed balance principle, and first-principles calculations are investigated. Compared with the case of monolayer MoS2, it is found that C-60/MoS2 MvdW heterostructures have lower interface reflectivity and type II band alignment, leading to obvious improvement of power conversion efficiency (PCE) from 0.27% to 1.40%. Moreover, the photovoltaic properties can be tuned by changing the array periodicity of the C-60 and the thickness of the MoS2, and the optimized PCE can be up to 5.35%. The results reveal that the modification of 0D C-60 is an effective strategy to enhance the photovoltaic properties of MoS2-based solar cells.
摘要：
Protection of entanglement from disturbance of the environment is an essential task in quantum information processing. We study the dynamic behaviours of quantum entanglement between two uncoupled qubits, which are immersed in a common phase decoherence environment. We examine the validity of the local non-Hermitian operation in the amplification of qubit–qubit entanglement. In particular, using analytical and numerical investigations, we show explicitly that the quantum entanglement of the two qubits can be greatly amplified by means of non-Hermitian operation.
通讯机构：
[Xiaolin Wei] D;Department of Physics & Hunan Institute of Advanced Sensing and Information Technology, Xiangtan University, Xiangtan, Hunan 411105 China<&wdkj&>College of Physics and Electronic Engineering, Hengyang Normal Univerisity, Hengyang 421002, China
关键词：
First-principle calculation;NRR;Single atom catalysts
摘要：
Single atom electrocatalysts show great potential to nitrogen reduction reaction (NRR). Here, we studied transition metals (V, Cr, Nb, Mo, Ta, W) doped on MoSe2 as single atom electrocatalysts by first-principles theory. We investigated different NRR pathways and its corresponding Gibbs free energy. It is found that W/MoSe2 has a better NRR catalytic activity than others due to the larger charge composition with N2 molecule. Furthermore, the limiting potential has a quasi-linear relationship with the N2 adsorption energy, which is also related to the changes of charge composition. The result highlights a new family of efficient TM/MoSe2 catalysts for NRR.
期刊：
BULLETIN DES SCIENCES MATHEMATIQUES,2021年173:103054 ISSN：0007-4497
通讯作者：
Saminathan Ponnusamy
作者机构：
[Liu, Gang] Hengyang Normal Univ, Hunan Prov Key Lab Intelligent Informat Proc & Ap, Coll Math & Stat, Hengyang 421002, Hunan, Peoples R China.;[Liu, Zhihong] Guilin Univ Technol, Coll Sci, Guilin 541004, Guangxi, Peoples R China.;[Ponnusamy, Saminathan] Indian Inst Technol Madras, Dept Math, Chennai 600036, Tamil Nadu, India.
通讯机构：
[Saminathan Ponnusamy] D;Department of Mathematics, Indian Institute of Technology Madras, Chennai-600 036, India
关键词：
Bohr inequality;Bohr radius;Bohr-Rogosinski inequality;Bounded analytic function;Symmetric function
摘要：
In this article, by combining appropriate refined Bohr's inequalities with some techniques concerning bounded analytic functions defined in the unit disk, we generalize and improve several Bohr-type inequalities for such functions. (C) 2021 Elsevier Masson SAS. All rights reserved.
摘要：
Several works on optical higher-order differential operations have recently attracted attention, particularly in image processing for edge detection. However, the inefficient differential operation leads to barriers to practical applications. Here, we report an anisotropic epsilon-near-zero slab to significantly enhance the transmission efficiency of second-order differentiators and discuss the Berry phase mechanism of this optical calculation process. Through a rigorous full-wave analysis of the process, we find that the conversion efficiency of differential operation depends on the spin-orbit interactions. Our scheme can strengthen the spin-orbit interaction by introducing anisotropy, which significantly enhances the transmission efficiency. We finally give transfer functions to reveal how to improve the efficiency and compare the quadratic coefficient among different systems. This highly efficient differentiation operation may develop significant applications in fast, compatible, and power-efficient ultrathin devices for data processing and biological imaging.
摘要：
Optical spin-Hall effect (SHE) exhibits many intriguing features as a linearly polarized (LP) light beam strikes an interface at incident angles around the Brewster angle, but the underlying physics remains obscure. Here, we elucidate the physics through reanalyzing this problem employing rigorous calculations and the Berry phase concept. As a circularly polarized (CP) light beam strikes an optical interface, the reflected light beam contains two components, a spin-flipped abnormal mode acquiring geometric phases (thus exhibiting a spin-Hall shift) and a spin-maintained normal mode without such phases. Strengths of these two modes are determined by the incident angle and the optical properties of the interface. Under the LP incidence, however, a spin component inside the reflected light beam must be the sum of normal and abnormal components of reflected light beams corresponding to CP incidences with different helicity, which thus sensitively depends on the incident angle. In particular, at incident angles near the Brewster one, reflection coefficients for two CP components exhibit opposite signs, leading to significant destructive interferences between normal and abnormal modes, finally generating highly deformed reflected light patterns with anomalously enhanced spin-Hall shifts. These findings can be extended to both reflected and transmitted cases with Brewster-like behaviors. Our analyses reinterpret previously discovered effects, providing an alternative understanding on the SHE of light.
作者机构：
[Xu, Qiang; Yu, Fu-Xing; Chen, Ping; Wang, Run; Zhang, Yue; He, Xiao-Li; Ma, Xing-Juan; Xiong, Zu-Hong; Jia, Ya-Lan; Zhang, Yong; Gao, Chun-Hong] Southwest Univ, Sch Phys Sci & Technol, MOE Key Lab Luminescence & Real Time Anal, Chongqing 400715, Peoples R China.;[Deng, Yan-Hong; Gao, Chun-Hong] Hengyang Normal Univ, Coll Phys & Elect Engn, Hunan Prov Appl Basic Res Base Optoelect Informat, Hengyang 421002, Peoples R China.
通讯机构：
[Chun-Hong Gao] S;School of Physical Science and Technology, MOE Key Laboratory on Luminescence and Real Time Analysis, Southwest University, Chongqing, 400715, China<&wdkj&>Hunan Provincial Applied Basic Research Base of Optoelectronic Information Technology, College of Physics and Electronics Engineering, Hengyang Normal University, Hengyang, 421002, China
摘要：
Tetraphenylphosphonium chloride (TPPCl) is used as an additive in the antisolvent for preparing the quasi-two Dimensional (quasi-2D) perovskite film. This strategy is not only beneficial for the morphology formation but also the phase tuning of the quasi-2D perovskite film. Highly efficient and stable perovskite light-emitting diodes (PeLEDs) were achieved with the maximum luminance of 35,000 cd/m2, the maximum current efficiency of 48.0 cd/A and the maximum external quantum efficiency (EQE) of 12.42%. Due to the reduced exciton quenching rate, improved charge carrier injection and transport ability, the electroluminescent performance of the TPPCl-based PeLEDs has been enhanced.
