bluuebunny/crossref_metadata_2025 huggingface dataset:
Dielectric waveguide with deep subwavelength mode confinement based on coupled nanowires
Authors: Yue Song  , Li Zhi  , Chen Jian-Jun  , Gong Qi-Huang  ,   State Key Laboratory for Mesoscopic Physics and Department of Physics,Peking University, Beijing 100871, China
Published: December 2020

Dielectric waveguide with deep subwavelength mode confinement based on coupled semiconductor nanowires is proposed.Through the coupling between two adjacent nanowires with high refractive indexes, light can be efficiently confined in the nano-gap between the nanowires with a low refractive index. Numerical simulations indicate that the effective mode area of such a waveguide can be as small as Λ20/200, which is one order of magnitude smaller than that of a single nanowire, and such a mode confinement is comparable to that of hybrid plasmonic waveguide. It is also shown that from the view of real applications, possible existing low refractive index oxidization layers of nanowires, low refractive index substrate and small deviation of nanowire dimensions do not have significant influence on the property of the waveguide. As the propagation length is theoretically infinite for dielectric waveguides, such a coupled nanowire waveguide with deep subwavelength mode confinement may have important applications in future integrated photonic circuits.
Strongly nonlocal spatial soliton propagation in lead glass
Authors: Shou Qian  , Jiang Qun  , Liang Yan-Bin  , Hu Wei  ,   Key Laboratory of Photonic Information Technology of Guangdong Higher Education Institutes, South China Normal University, Guangzhou 510631, China
Published: December 2020

The soliton propagations in lead glass separately with circle and rectangle boundaries are theoretically and experimentally investigated. Based on the image beam method the soliton propagation in lead glass is comprised of two independent processes: the soliton forming and the soliton steering as a whole. The soliton-forming process is boundary independent, which is caused by the source beam itself induced refractive index distribution. The force which leads to the soliton steering essentially comes from the boundary effect and is equal to the force between the soliton beam and all of the image beams. The numbers of the images are one and infinite respectively for the boundaries of circle and rectangle. This results in a different steering force with a different boundary. The closed-form solutions of the soliton critical power and the steering trajectories are in good agreement with the experimental results.
A universal cryptosystem based on two simple physical models
Authors: Zhou Qing  , He Xiao-Dong  , Hu Yue  ,   College of Computer Science, Chongqing University, Chongqing 400044, China
Published: December 2020

Digital objects, such as images, videos, digital warehouse are diverse in the sense of dimension and representation-precision. Conventional encryption algorithms treat all digital objects as one-dimensional data, thus they cannot make it effective to take advantage of their spatial characteristics. A cryptosystem is constructed by combining RE arrays with extended HPP model we proposed. The cryptosystem is applicable to digital object of arbitrary dimension and representation-precision. Moreover, it has the merits of spatiality, parallelism, and high efficiency. Experimental results demonstrate that the cryptosystem has satisfactory randomness and sensitivity.
First-principles study of ordered structures in Ba0.5Sr0.5TiO3
Authors: He Jian-Ping  , Lü Wen-Zhong  , Wang Xiao-Hong  ,   Department of Electronic Science and Technology, Huazhong University of Science and Technology, Key Laboratory of Functional Materials for Electronic Information (B) (Huazhong University of Science and Technology), Ministry of Education, Wuhan 430074, China
Published: December 2020

The lattice structures and the electronic structures of different ordered structures in Ba0.5Sr0.5TiO3 are calculated by the first-principles method. The results of geometry structures and overlap populations reveal that the BST{100} ordered structure is tetragonal. The O atoms in Ti-O octahedron parallel to Ba plane and Sr plane are shifted ward Sr plane by 0.065 Å. And the Ti atom in Ti-O octahedron has a off-center displacement of 0.040 Å. The off-center displacements of O atoms and Ti atoms result in the distortion of Ti-O octahedron, and the occurrence of antiparallel spontaneous polarization. Therefore the BST{100} ordered structure is in antiferroelectric phase. The O atoms in BST{110} ordered structure also have a off-center displacement of 0.029 Å, while the Ti atom in Ti-O octahedron is still in-center. This tetragonal structure is in paraelectric phase. The BST{111} ordered structure is in cubic paraelectric phase. The calculated density of states shows that the hybridization between Ti 3d and O 2p plays a primary role in the generation of ferroelectricity. The results of the present work imply that the local order of A site can significantly influences the structural phase transition of disordered BST solid solution.
An model of tunneling gate current for uniaxially strained Si nMOSFET
Authors: Wu Hua-Ying  , Zhang He-Ming  , Song Jian-Jun  , Hu Hui-Yong  ,   Microelectronics Insititute, Xidian University, key Laboratory of Wide Band-Gap Semiconductor Materials and Devices, Xi’an 710071, Chnia
Published: December 2020

Based on quantum mechanics, a tunneling current of uniaxially strained Si nMOSFET is bulit. The relationships between the tunneling current and device structure parameter, biased voltage and stress are analyzed. The simulation result is shown to accord well with the reported experimentalal result, implying that our model is correct. Our result is also compared with the result of biaxially stressed silicon nMOSFET, which shows that the current of uniaxially straining Si nMOSFET is lower than that of biaxially stressed silicon nMOSFET, and so uniaxial devices have advantages over biaxial devices. The model has a definite physical mechanism and it is suitable not only for uniaxially strained Si nMOSFET, but also for uniaxially strained Si pMOSFET,as long as changing the relevant parameters.
Comprehensive Survey for the Frontier Disciplines Progress in lattice, magnetic and electronic transport properties of antiperovskite Mn3AX
Authors: Ding Lei  , Wang Cong  , Chu Li-Hua  , Na Yuan-Yuan  , Yan Jun  ,   Center for Condensed Matter and Material Physics, School of Physics, Beihang University,Beijing 100191,China
Published: December 2020

In recent years, it was found that antiperovskite compounds Mn3AX(A=Cu, Zn, Sn, Ni, Al, Ga etc.;X=N/C) exhibit abundant physical properties. Their useful functionalities arising from the interplay between crystal lattice and magnetism, such as superconductivity, giant magnetoresistance, near-zero temperature coefficient of resistance, negative thermal expansion, magnetostriction, piezomagnetic effect, the magnetocaloric effect, etc, have aroused the great interest. The thorough study of the crystal structure and physical properties of Mn3AX is important for understanding the relationship of "nature-structure". In this article, we review the progress in the peculiar physical properties of Mn3AX, especially the progress of strong correlations among lattice, electronic transport and magnetic ordering. Meanwhile, the control over the lattice,magnetoresistance and magnetic transition is also reviewed. Finally, some perspectives are proposed.
Influence of tensile stress on the phase formation and electronicproperties of Pb(Zr,Ti)O3 film at morphotropic phase boundary
Authors: Wen Xin-Yi  , Wang Yun-Bo  , Zhou Wen-Li  , Gao Jun-Xiong  , Yu Jun  ,   Department of Electronic Science & Technology, Huazhong University of Science and Technology, Wuhan 430074, China
Published: December 2020

Pb(Zr0.52,Ti0.48)Nb0.04O3 (Nb-doped PZT, PZTN) films are deposited on Pt/TiOx/SiO2/Si substrates with BaPbO3(BPO) buffer layers by RF-magnetron sputtering method. The magnitudes of tensile stress in PZTN films can be changed by adjusting the thickness of BPO layer. For PZTN films with 68 nm and 135 nm-BPOs, the tensile stresses measured by 2θ-sin2ψ method are 0.786 and 0.92 GPa respectively. Enhanced ferroelectric is observed in PZTN film with raised tensile stress. The remanent polarization and the coercive field for PZTN films with tensile stresses of 0.786 GPa and 0.92 GPa are 41.2μC/cm2(70.7 kV/cm) and 44.1μC/cm2(58.1 kV/cm) respectively. The leakage current decreases from 6.57×10-7A/cm-2 to 5.54×10-8A/cm-2 while tensile stress of PZTN film is raised from 0.786 to 0.92GPa. Fine XRD scan is performed with grazing incidence geometry to investigate the phase composition of PZTN films. Rietveld analysis shows that an increased tensile stress in PZTN film can promote the amount of monoclinic phase,which may be the reason for the ferroelectric property improvement.
Near-infrared broadband emission spectroscopic properties of Bi: α-BaB2O4 single crystal induced by electron irradiation
Authors: Fang Xiao-Ming  , Yang Qiu-Hong  , Guo Xing  , Su Liang-Bi  , Zhao Heng-Yu  , Yu Ping-Sheng  , Li Xin-Nian  , Xu Jun  ,   Applied Radiation Institute, Shanghai University, Shanghai 201800, China;,   Department of Electronic Information Materials, School of Materials Science and Engineering, Shanghai University, Shanghai 200072, China;,   Department of Electronic Information Materials, School of Materials Science and Engineering, Shanghai University, Shanghai 200072, China;Key Laboratory of Transparent and Opto-functional Inorganic Materials, Chinese Academy of Sciences, Shanghai Institute of Ceramics, Shanghai 201800, China;,   Key Laboratory of Transparent and Opto-functional Inorganic Materials, Chinese Academy of Sciences, Shanghai Institute of Ceramics, Shanghai 201800, China
Published: December 2020

Bi:α-BaB2O4 crystal samples are grown by the traditional Czochralski method and the obtained samples are irradiated by electron beam. Absorption and emission spectra of the samples are measured at room temperature before and after their electron irradiation. Under 808 nm LD excitation, broadband (FWHM at 52 nm) near-infrared emissions centered at about 1135 nm are observed in electron-irradiated Bi:α-BaB2O4 samples. Both the emissions are believed to be due to Bi+ ions. Electron beam helps to reduce Bi3+ and Bi2+ into univalence. The formation processes in the samples with different radiation doses are not the same, which is primarily discussed in this work.
Analysis and forecasting of heavy-rainfall event by strong convection
Authors: Ran Ling-Kun  , Zhou Yu-Shu  , Yang Wen-Xia  ,   (1)Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029,China; (2)Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029,China;Hebei Key Laboratory of Meteorology and Ecological Environment, Shijiazhuang 050021,China
Published: December 2020

For the case of severe convection occurring in the southern region of North China on July 8, 2009, the three dynamical factors, namely, vertical component of convective vorticity vector, moist thermodynamic advection parameter and wave-activity density are diagnosed. The result shows that the anomalous-value regions of dynamical factors are located mainly in middle and lower troposphere over the strong precipitation area. Since the dynamical factors can effectively describe the synthetical characteristics of strong convective system, such as vertical shear of horizontal wind, advection of potential temperature, vorticity perturbation and baroclinicity of moist atmosphere, they correspond to the observation of 6-h accumulative rainfall in horizontal distribution patterns. Using the 6-h, 12-h, 18-h and 24-h forecasting dataset of U.S. NCEP/NCAR 0.5-Degree GFS, the dynamical factors are calculated to analyze their indications of precipitation forecasting during a longer period. The results show that during June 2 – Oct 1, 2009, the 6-h, 12-h, 18-h and 24-h forecasted dynamical factors each have an indication of strong precipitation. The moist thermodynamic advection parameter suggests that the precipitation is best among the three dynamical factors.
Comparison between sliding spectral method and back propagation method for radio occultation data
Authors: Guo Peng  , Xu Xian-Sheng  , Huang Si-Xun  , Xiang Jie  ,   (1)Institute of Meteorology, PLA University of Science and Technology, Nanjing 211101, China; (2)Shanghai Astronomical Observatory, Chinese Academy of Sciences, Shanghai 200030, China; (3)Shanghai Institute of Applied Mathematics and Mechanics, Shanghai University, Shanghai 200072, China
Published: December 2020

The sliding spectral (SS) method of processing radio occultation data in multipath zone is introduced in detail and compared with back propagation (BP) method through processing simulated data and COSMIC soundings. The modeled signals are inverted with the use of two methods: BP method and SS method. Both methods can solve the problem of calculating bending angle profiles in multipath regions. Better agreement with Abel integral is indicated by the BP method. The BP method is almost free from noise, while the SS method will be affected severely by noise. About 4500 COSMIC radio occultation soundings are retrieved by the BP method and the SS method, and the statistical comparison of retrieved refractivity with that from ECMWF analyses shows that the SS method has better penetration ability than the BP method in the lower moist troposphere. The mean of fractional difference in refractivity retrieved by the BP method is generally smaller than that by the SS method.
Analytical method of softness abrasive two-phase flow field based on 2D model of LSM
Authors: Ji Shi-Ming  , Weng Xiao-Xing  , Tan Da-Peng  ,   Key Laboratory of Special Purpose Equipment and Advanced Manufacturing Technology, Zhejiang University of Technology, Ministry of Education, Hangzhou 310014, China
Published: December 2020

To solve the precision machining problem in the structural surface mould manufacturing process, a new no-tool precision machining method based on softness abrasive flow machining (SAFM) is proposed. The key technology of SAFM is the characteristic analysis of two-phase flow. To solve this problem, a two-dimensional model of the two-phase flow is established by the topological structure transformation of level set method. This mechanics model is used to simulate the motion of the turbulent flow and work out the characteristic parameters of abrasive two-phase flow. The simulation results show that this model can preferably simulate the motion of the two-phase flow and calculate velocity and pressure with k- model and Preston equation. Therefore the feasibility of SAFM can be confirmed and a good reference can be provided for the further research.
Relation analysis between starting voltage and input voltage for a magneticaly insulated linear oscillator
Authors: Chen Dai-Bing  , Wang Dong  , Qin Fen  , Wen Jie  , Jin Xiao  , An Hai-Shi  , Zhang Xin-Kai  ,   Laboratory of High Power Microwave Technology, Institute of Applied Electronics, Chinese Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

Resorting to particle-in-cell (PIC), simulation and experimental investigation, the phenomenon is observed that the starting voltage increases with the increase of input operation voltage of a magnetically insulated transmission linear oscillator (MILO). Therefore, PIC simulation and theoretical analysis are carried out for further study. The key factor responsible for the phenomenon is found, that is, the bigger the operation voltage and the bigger the rise slope of the operation voltage is, and the bigger the starting voltage is; when the rise slope of the operation voltage is infinite, the starting voltage is equal to the operation voltage. Therefore, the variation of the rise slope of the input voltage is the key factor that causes the variation of the starting spot for an MILO; when there is no change of the rise slope of the voltage, the starting spot for the same MILO will not change, and the starting voltage will not change either; when there is the increase of the rise slope of the input voltage, the starting voltage for the same MILO will increase accordingly. In addition, the expression of the self-insulating critical current for an MILO is modified partly.
Structure and potential energy function for the ground state (X2)of TiN molecule
Authors: Xiong Xiao-Ling  , Wei Hong-Yuan  , Chen Wen  ,   Institute of Nuclear Physics and Chemistry, Chinese Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

Based on the group theory and the theory of atomic-molecular reaction statics, the reasonable dissociation limit for the ground state (X2) of TiN molecule is derived. Optimization calculation is performed using different groups of density functional method including BP86, B3P86, B3LYP, B3PW91 with different basis sets. The results show that the BP86 method with D95V++ (d, P) basis set for nitrogen atom and 6-311++G** basis set for titanium atom is the best group for calculating the geometric structure, the vibration frequency and the dissociation energy. The potential energy curves and the relevant spectroscopic constants for the ground state of TiN are obtained by least square fitting to the Murrell-Sorbie analytical potential function. All calculation results are in good agreement with the experimental data.
Quantum evolution of entanglement property in two-qubit and oscillator coupling system
Authors: Xia Jian-Ping  , Ren Xue-Zao  , Cong Hong-Lu  , Wang Xu-Wen  , He Shu  ,   College of Science, Southwest University of Science and Technology, Mianyang 621010, China;,   Physics Group, Beijing Jiaotong University Hai Bin College, Huanghua 061100, China
Published: December 2020

Under the non-rotating wave approximation, the quantum evolution of entanglement property of a two-qubit and oscillator coupling system is accurately investigated by the method of coherent-state orthogonalization expansion. The property of the ground state for qubit-oscillator system and the difference between qubit-oscillator entanglement and qubit-qubit entanglement when resonant vibration occurs are discussed. The calculation results show that when the external field is not taken into consideration, the qubit-qubit entanglement reduces from 1 to 0 rapidly with the increase of coupling strength, indicating the strong sensitivity of the entanglement to the coupling strength. On the contrary, with the increase of the coupling the qubit-oscillator entanglement rises from 0, but does not reach the maximum value 2. At the beginning, when the two qubits do not entangle, the vacuum field does not lead to the entanglement in weak coupling. However, the strong coupling can induce the sudden appearance of the entanglement.
Numerical study on coherent keV x ray generation by the interaction of ultra-short intense lasers with thin solid foils
Authors: Jia Qian-Qian  , Wang Wei-Min  , Dong Quan-Li  , Sheng Zheng-Ming  ,   Laboratory of Optical Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China;,   Key Laboratory of Laser Plasma of the Education Ministry, Department of Physics, Shanghai Jiao Tong University, Shanghai 200240, China
Published: December 2020

The scheme of x ray generation by the interaction of ultra-short intense laser puls with two thin solid foils is re-investigated by one-dimensional numerical simulation. Attention is paid particularly to the effects of the thickness and the density distribution of the source target on the frequency spectrum and the conversion efficiency of the produced x ray emission, where the source target provides a relativistic electron layer. When the thickness of the source target is comparable to or smaller than the wavelength of x ray /4x2 ( is the wavelength of the incident laser), quasi-monochromatic x ray spectrum can be generated. Otherwise the spectrum will be broadened significantly and the maximum frequency will decrease rapidly. In addition, the presence of inhomogeneous preplasma in front of the foil will induce a similar change of the spectrum.
First-principles analysis of properties of Cu surfaces
Authors: Shu Yu  , Zhang Yan  , Zhang Jian-Min  ,   College of Physics and Information Technology, Shaanxi Normal University, Xi'an 710062, China
Published: December 2020

Using first-principles pseudopotential plane wave method, the energy, atomic geometry and electronic density of states of FCC Cu crystal and its (111), (110) and (100) surface models were calculated and analyzed. According to the calculated results of the surface energy, the structural stability of the Cu surfaces increases for Cu (110), Cu (100), Cu (111) surfaces successively. The relaxation extent of the surface atoms decreases successively with the increasing the number of the layers. For the inwards relaxation of the surface layer atoms, Cu (110) surface moves maximum, Cu (100) takes second place, Cu (111) surface moves least. It was found that the relaxation of the surface atom layers not only causes the change of geometrical structures of the surface models but also leads to the change of peak contour of density of states (DOS) of surface layer atoms comparing with crystal inside. The increment of the total energy caused by these change is the main reason of the surface energy. And that the Cu (110) surface having higher activity than that of Cu(111) and Cu(100) surfaces may be attributed to its apparent rising of the surface layer atoms DOS in the high energy level.
The variations in composition and bonding configuration of SiNx film under high annealing temperature treatment
Authors: Jiang Li-Hua  , Zeng Xiang-Bin  , Zhang Xiao  ,   Department of Electronic Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, China
Published: December 2020

Non-stoichiometric silicon nitride (SiNx) thin films are deposited on p-type crystalline silicon substrates at low temperature (200 ℃) using ammonia and silane mixtures by plasma enhanced chemical vapor deposition. The evolutions of SiN, SiH and NH bonding configurations, the variations of Si 2p and N 1s electron binding energy and the ratio R of nitrogen to silicon atoms in SiNx films annealed at temperature in a range of 5001100 ℃ are investigated at room temperature by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS), respectively. The relationship between the evolutions of FTIR and XPS spectroscopy of the samples at different annealing temperatures and the variations of bonding configurations of Si, N and H atoms is discussed in detail. According to the arguments about FTIR and XPS spectroscopy we conclude that when the annealing temperature is lower than 800 ℃, the breakings of SiH and NH bonds in the SiNx films lead mainly to the formation of SiN bonds; when the annealing temperature is higher than 800 ℃, the breakings of SiH and NH bonds are conducible to the effusion of N atoms and the formation of silicon nanoparticles; when the annealing temperature equals 1100 ℃, the N2 react on the SiNx films to cause the ratio R of nitrogen to silicon atoms to inerease. These results are useful for controlling the probable chemical reaction in SiNx films under high annealing temperatures and optimizing the fabrication parameters of silicon nanoparticles embedded in SiNx films.
Effects of sodium and potassium ion channel fluctuation on the spatiotemporal patterns of neuronal network
Authors: Liu Shao-Bao  , Wu Ying  , Hao Zhong-Wen  , Li Yin-Jun  , Jia Ning  ,   State key Laboratory for strength and Vibration, School of Aerospace, Xi’an Jiaotong University, Xi’an 710049, Chain;,   Department of Engineering Mechanics, School of Sciences, Xi’an University of Technology, Xi’an 710048, China
Published: December 2020

Taking into account sodium and potassium ion channel noises, the evolution of the patterns of neuronal networks is investigated. No matter what kind of ion channel noise is working, with coupling coefficient increasing, the spatiotemporal patterns of the neuronal network can be evolved into spiral waves when temperature and noise strength are given, and there is a coupling coefficient threshold for forming a spiral wave. The analysis shows that sodium ion channel noise contributes to the formation of spiral waves in neurons network, while the potassium ion channel noise is not conducive to the formation of spiral waves. In addition, it is found that lower temperature can make the neurons network more sensitive to noise. Finally, the transformation of spiral waves into target waves, in the case of specific parameters is discussed.
A second order gradient representation of mechanics system
Authors: Lou Zhi-Mei  , Mei Feng-Xiang  ,   Department of Physics, Shaoxing University, Shaoxing 312000, China;,   Department of Mechanics, Beijing Institute of Technology, Beijing 100081, China
Published: December 2020

A gradient representation and a second order gradient representation of the mechanics system are studied. The differential equations of motion of the holonomic and nonholonomic mechanics systems are expressed in the canonical coordinates. A condition under which the system can be considered as a gradient system is given. A condition under which the system can be considered as a second order gradient system is obtained. Two examples are given to illustrate the application of the result.
Limited penetrable visibility graph for establishing complex network from time series
Authors: Zhou Ting-Ting  , Jin Ning-De  , Gao Zhong-Ke  , Luo Yue-Bin  ,   School of Electrical Engineering and Automation, Tianjin University, Tianjin 300072, China
Published: December 2020

We propose an improved visibility graph method, i.e., limited penetrable visibility graph, for establishing complex network from time series. Through evaluating the degree distributions of three visibility algorithms(visibility graph, horizontal visibility graph, limited penetrable visibility graph), we find that the horizontal visibility graph cannot distinguish signals from periodic, fractal, and chaotic systems; for fractal signal, the degree distributions obtained from visibility graph and limited penetrable visibility both can be well fitted to a power-law(scale-free distribution), but the anti-noise ability is not good; for periodic and chaotic signals, the limited penetrable visibility graph shows better anti-noise ability than visibility graph. In this regard, we use the limited penetrable visibility graph to extract the network degree distribution parameters from conductance fluctuating signals measured from oil-gas-water three-phase flow test. The results indicate that combination parameters of network degree distribution can be used to classify typical three phase flow patterns, e.g., oil-in-water bubble flow, bubble-slug transitional flow and slug flow.
Infrared quantum cutting of ErP5O14 noncrystalline glass
Authors: Chen Xiao-Bo  , Yang Guo-Jian  , Li Song  , Yang Xiao-Dong  , Liu Da-He  , Chen Ying  , Ding Feng-Lian  , Wu Zheng-Long  ,   Applied Optics Beijing Area Major Laboratory and Analytical Testing Center, Beijing Normal University, Beijing 100875, China
Published: December 2020

The infrared quantum cutting phenomena, which is an international hot research field, of Er1.0P5O14 noncrystalline glass are studied by the present paper for the first time. The 1537.0nm infrared fluorescence of Er1.0P5O14 noncrystalline glass is confirmed to be the multi-photon quantum cutting fluorescence by computation and comparison between absorption and excitation spectra. It is found that the 4I13/2→4I15/2 quantum cutting fluorescence is very strong, induced by the excited 2H11/2, 4G11/2, and 4G9/2 energy levels. Its mechanism is thoroughly analyzed based on the calculation of spontaneous emission rates, nonradiative multiphonon relaxation rates and energy transfer rates. It is found the strong downconversion energy transfers {2H11/2→4I9/2,4I15/2→4I13/2},{4G11/2→4I13/2, 4I15/2→2H11/2},{4G9/2→4F7/2,4I15/2→4I13/2} 和 {4G9/2→4I13/2, 4I15/2→2H11/2} are responsible for the strong infrared three-photon and four-photon quantum cutting fluorescence of Er1.0P5O14 noncrystalline glass. The present research is significant for enhancing solar cell efficiency.
Characteristics of the photovoltaic device with nanohole array antireflection coating layer
Authors: Wang Ning  , Zhu Yong  , Wei Wei  , Chen Jian-Jun  , Li Ping  , Wen Yu-Mei  ,   Key Laboratory for Optoelectronic Technology and System, Education Ministry of China, College of Optoelectronic Engineering, Chongqing University, Chongqing 400044, China
Published: December 2020

The optical characteristic of the nanohole array film is analyzed by using rigorous coupled wave, and the nanohole array film is proposed to serve as photovoltaic device anti-reflection film to improve the device absorption and efficiency. According to theoretical analysis, nanohole array anti-reflection film has a better anti-reflection effect than the monofilm and can better enhance the photovoltaic device's efficiency, especially in a speetral range of 400 nm600 nm; the optimal period of the nanohole array is 500 nm, the optimal filling factor of the nanohole array is 0.2 and the optimal thickness of the nanohole array is 110 nm. In order to testify the optical effect of nanohole array, the nanohole arrays of different sizes are made by the micro-nano processing technology in the anti-reflection film of the 200 m Si Detector, and a relevant experimental system is set up. With the optimized nanohole arrays, the short circuit currents of the experimental sample are increased ～6% in a 4001100 nm spectral range, especially, increased ～15% in a 400 nm-600 nm spectral range.
Solving method of a class of reactive diffusion model for atmospheric plasmas
Authors: Shi Lan-Fang  , Ouyang Cheng  , Chen Li-Hua  , Mo Jia-Qi  ,   College of Mathematics and Statistics, Nanjing University of Information Science and Technology, Nanjing 210044, China;,   Faculty of Science, Huzhou Teacher College, Huzhou 313000, China;,   Department of Mathematics and Computer Science,Fuqing Branch of Fujian Normal University, Fuqing 350300, China;,   Department of Mathematics, Anhui Normal University, Wuhu 241003, China
Published: December 2020

A class of reactive diffusion model for atmospheric plasmas is studied. The asymptotic solution is obtained by using the singular perturbation method, and the validity of the solution is proved.
Noise-induced synchronization of two-dimensional complex spatiotemporal systems
Authors: Du Lin  , Xu Wei  , Xu Yong  , Wang Liang  ,   Department of Applied Mathematics, Northwestern Polytechnical University, Xi'an 710072, China
Published: December 2020

A type of noise-induced synchronization in two-dimensional (2D) complex spatiotemporal system is studied in this paper. First, we employ a 2D complex Ginzburg-Laudau equation (CGL) to present spatiotemporal chaos. Then the synchronization in the CGL equation driven by spatiotemporal noise is studied. Theoretically, the critical control intensity is obtained by linear stability analysis of a constant forced CGL system. Combining with randomness and non-zero mean of the noise, we reveal the mechanism of synchronization and give the required conditions for control parameters and noise intensity resulting in synchronization theoretically and numerically. A complete synchronization in a pair of uncoupled CGL equations is achieved. A good agreement between the theoretical analyses and the numerical results is obtained.
Study on properties of the H1 photonic crystal slab cavity using the effective index perturbation method
Authors: Zhou Wen-Fei  , Ye Xiao-Ling  , Xu Bo  , Zhang Shi-Zhu  , Wang Zhan-Guo  ,   Key Laboratory of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China;,   Department of Physics, Tsinghua University, Beijing 100084, China
Published: December 2020

In this paper the effective index perturbation technique in combination with two-dimensional (2D)/three-dimensional (3D) plane wave expansion methods is used to predict resonant mode frequencies of donor-like and acceptor-like H1 photonic crystal slab cavity, and their results are very close to the ones obtained by three-dimensional finite difference time domain method. For donor-like H1 photonic cavity, when the perturbed effective index by matching dielectric band edge is used, there is a relatively small frequency difference; however, for acceptor-like H1 photonic cavity, the matching criterion should be set at middle band position. The effective index perturbation method can not only save computation time and computer memory with reducing dimensionality (from 3D to 2D), but also ensure the accuracy of the simulation results, which is substantially important for the extensive application of photonic crystal slab cavity.
Nonlinear Rosen-Zener transition of Fermi superfluid gases
Authors: Meng Hong-Juan  , Yang Yang  , Wang Wen-Yuan  , Qi Peng-Tang  , Ma Yun-Yun  , Ma Ying  , Wang Shan-Jin  , Duan Wen-Shan  ,   Key Laboratory of Atomic and Molecular Physics and Functional Materials of Gansu Province, College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070, China;,   School of Electronic Engineering, Dongguan University of Technology, Dongguan 523808 China
Published: December 2020

By considering the contribution of the higher order term representing the lowest approximation of beyond mean field correction and taking Roser-Zener tunneling as the underling process, we study the nonlinear Rosen-Zener transition of Fermi superfluid gas in a two-level system. We find that the nonlinearity can affect the quantun trasition in the fast scan limit and the adiabatic limit. We also derive the analytical expression for the of rectangular oscillation period dependent on nonlinear parameter. This provides a theoretical basis for a deeper understanding of the basis properties of Fermi gases.
Research on eye location algorithm robust to driver's pose and illumination
Authors: Zhang Wei  , Cheng Bo  , Zhang Bo  ,   State Key Laboratory of Automotive Safety and Energy, Department of Automotive Engineering, Tsinghua University, Beijing 100084, China
Published: December 2020

Driver's drowsiness is one of the major causes of road accidents. The monitoring of a given driver's eye state by the use of a camera is considered to be a promising way to detect driver's drowsiness due to its accuracy and non-intrusiveness. However, eye location remains a challenging vision problem because of the constantly changing of illumination and driver's pose. Active shape model (ASM) is introduced in this paper to align the face. Though the ASM is a powerful statistical tool, it can suffer from changes in illumination and posture. Three contributions are involved in this paper. First, in order to maximize the tolerance of the ASM algorithm to illumination changes, we propose a robust ASM method with a novel local texture model learned from the self-quotient image instead of the original image. Second, a double layer overall shape model is proposed to enhance the adaptability of ASM. Third, strong constraints are achieved by an on-line learning of the distribution characteristics of the model parameters. The results show that the proposed algorithm is robust to the variation of illumination and driver's pose.
First-principles study of Ni-based metal compound
Authors: Tang Zhi-Qiang  , Qi Yan-Yong  , Yi Yong  , Ding Zhi-Jie  ,   Southwest University of Science and Technology and Laboratory for Extreme Conditions Matter Properties, Mianyang 621010, China
Published: December 2020

The rare earth-transition (R-T) intermetallics has excellent physical and chemical properties. The electronic structure, the band structure and the magnetic properties of the compound Ni13Nd3B2 are studied by using the first-principles plane wave pseudopotential method and the local spin-density approximation (LSDA). The calculation results indicate that this system is a metallic conductor with a very small band gap. The system has very complex bonding, where Nd atoms and the neighboring Ni and B atoms form ionic banding, whereas Ni atoms and the neighboring Ni atoms form covalent bonding. Under LSDA approximation, the system has Nd-Ni ferromagnetic coupling, and the total magnetic moment ( 8.4329B) is provided by the local Nd magnetic moment. The Nd-4f, Ni-3p, Nd-5p electron spin splittings due to spin polarization result in the magnetic system.
Epitaxial growth of thick Ge layers with low dislocation density on silicon substrate by UHV/CVD
Authors: Chen Cheng-Zhao  , Zheng Yuan-Yu  , Huang Shi-Hao  , Li Cheng  , Lai Hong-Kai  , Chen Song-Yan  ,   Department of Physics, Semiconductor Photonics Research Center, Xiamen University, Xiamen 361005, China;,   Department of Physics and Electronic Engineering, Hanshan Normal University, Chaozhou 521041, China
Published: December 2020

Thick Ge epitaxial layers are grown on Si(001) substrates in the ultra-high vacuum chemical vapor deposition system by using the method of low temperature buffer layer combining strained layer superlattices. The microstructure and the optical properties of the Ge layers are characterized by double crystal X-ray diffraction, HRTEM, AFM and photoluminescence spectroscopy. The root-mean-square surface roughness of the Ge epilayer with a thickness of 880nm is about 0.24 nm and the full-width-at-half maximum of the Ge peak of the XRD profile is about 273. The etch pit density related to threading dislocations is less than 1.5106 cm-2. The direct band transition photoluminescence is observed at room temperature and the photoluminescence peak is located at 1540 nm. It is indicated that the Ge epitaxial layer is of good quality and will be a promising material for Si-based optoelectronic devices
Multivariate chaotic time series prediction based on extreme learning machine
Authors: Wang Xin-Ying  , Han Min  ,   Faculty of Electronic Information and Electrical Engineering, Dalian University of Technology, Dalian 116023, China
Published: December 2020

For multivariate chaotic time series prediction problem, a prediction based on input variable selection and extreme learning machine is proposed in this paper. The multivariate chaotic time series is reconstructed in phase space, and a mutual information based method is used to select the input variables, which have high statistics information with the output variables. The extreme learning machine is conducted to model the multivariate chaotic time series in the phase space by utilizing its approximation capability. In order to improve the prediction accuracy, a model selection algorithm is conducted for extreme learning machine to choose an expected minimum risk prediction model. Simulation results based on Lorenz, Rssler multivariate chaotic time series and Rssler hyperchaotic time series show the effectiveness of the proposed method.
Phase stability, crystal structure and thermoelectric properties of Cu doped AgSbTe2
Authors: Zhang He  , Luo Jun  , Zhu Hang-Tian  , Liu Quan-Lin  , Liang Jing-Kui  , Rao Guang-Hui  ,   State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China;,   Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
Published: December 2020

CuxAg1-xSbTe2 samples withx = 00.3 are prepared by a combined process of melt-quenching and spark plasma sintering (SPS). X-ray powder diffraction (XRD) analysis indicates that single phase samples with the NaCl-type structure are obtained for the Cu-doped samples before SPS treatment, whereas a small quantity of Ag2Te impurities coexist with the main cubic phase for the sample without Cu. According to our thermoanalysis and XRD results, the substitution of Cu for Ag can effectively prevent the precipitation of Ag2Te, but this also leads to the presence of a minor amorphous phase in the melt-quenched sample. The amorphous phase crystallizes into Sb7Te metastable phase at about 540 K, which finally transforms into the stable Sb2Te3 compound. After the SPS treatment of the melt-quenched sample, the sample withx=0.1 remains a single phase with the face-centered-cubic crystal structure, while Sb7Te and Sb2Te3 are precipitated as the second phases for the samples withx = 0.2 and 0.3, respectively. The electrical conductivity increases and the Seebeck coefficient decreases with the addition of Cu due to the existence of the second phase in the samples withx = 0.2 and 0.3. Accordingly, thermal conductivities also increase with the addition of Cu, leading to the reduced thermoelectric performance of thex= 0.2 and 0.3 samples. For the sample withx = 0.1, its power factor is comparable to that of the literature reported AgSbTe2 compound. As a result of so-called alloying effect, the phonon scattering effect is enhanced due to the partial replacement of Ag by Cu, leading to the reduced thermal conductivity of thex = 0.1 sample. Therefore, the Cu0.1Ag0.9SbTe2 sample exhibits the promising thermoelectric performance and a dimensionless thermoelectric figure of merit (ZT) value of 1 is achieved at 620 K.
Design and fabrication of SiO2/Si3N4 dielectric distributed Bragg reflectors for ultraviolet optoelectronic applications
Authors: Li Zhi-Cheng  , Liu Bin  , Zhang Rong  , Zhang Zhao  , Tao Tao  , Xie Zi-Li  , Chen Peng  , Jiang Ruo-Lian  , Zheng You-Dou  , Ji Xiao-Li  ,   National Laboratory of Solid State Microstructures, Key Laboratory of Advanced Photonic and Electronic Materials of Jiangsu Province, School of Electronics Science and Engineering, Nanjing University, Nanjing 210093, China;,   Semiconductor Lighting Research and Development Center, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
Published: December 2020

In this paper, we design a SiO2/Si3N4 dielectric distributed Bragg reflector (DDBR) by the transfer-matrix method, which is grown by plasma-enhanced chemical vapor deposition on sapphire (0001). There exists a slight difference between theoretical and experimental results in peak wavelength (～ 10 nm). The peak wavelength is blue shifted with the number of DDBR pairs increasing. The 13-pair DDBR provides a 58 nm wide stop band centered at 333 nm with a maximal reflectivity of higher than 99%, as the refractive index ratio of Si3N4 to SiO2 is relatively high. It is proved by the scanning electron microscope and atomic force microscope measurements that the variations of thickness and roughness of Si3N4 layer with respect to SiO2 layer during growth contribute to the blue shift of peak wavelength. The X-ray reflectivity measurements indicate that the interfacial degradation of the samples has little effect on the maximum reflectivity, and the relatively poor quality of SiO2 compared with Si3N4 may be one of the reasons that cause the difference between the measurements and simulations.
Rovibrational population transfer controlled by two overlapping pulses
Authors: Niu Ying-Yu  , Wang Rong  , Xiu Jun-Ling  ,   School of Science, Dalian Jiaotong University, Dalian 116028, China
Published: December 2020

Rovibrational population transfer is controlled by a two-overlapping- pulse scheme in which the frequency ratio of the two pulses is 1:3. The calculated results show that nearly 100% of the population can be transferred from initial state |0,0to target state |3,1. The probability of population transfer can be controlled by pulse phase. When 1 =1.68 , the two pulses can be increased mutually and the probability of population transfer is also increased. When 1 =0.64 , the two pulses can be offset mutually and the probability of population transfer is reduced. The intensity of the second pulse has a significant effect on the population transfer.
Photoinduced coherent acoustic-phonons in Fe/Si film
Authors: Zhang Zheng-Bing  , Ma Xiao-Bai  , Jin Zuan-Ming  , Ma Guo-Hong  , Yang Jin-Bo  ,   Department of Physics, Shanghai University, Shanghai 200444, China;,   State Key Laboratory for Artificial Microstructure and Mesoscopic Physics, Peking University, Beijing 100871, China
Published: December 2020

High frequency coherent acoustic-phonons are excited in Fe/Si film by using femtosecond pump-probe technique. The dynamics of coherent acoustic-phonons can be fitted well to a classical damped harmonic function. The frequency and the dephasing time of the observed acoustic-phonons are 0.25 THz and 12 ps, respectively, which are independent of pumping photo-energy and fluence. Moreover, the amplitude of the coherent acoustic-phonons is linearly proportional to the fluence. The critical parameter (12e-ph/T) is calculated to be about 0.6, which indicates that the electron pressure might play a significant role in driving coherent acoustic phonons. The thickness and the mass density of the film are required to determine the out-of-plane elastic constant C～283 GPa of the Fe/Si film.
Analysis of characteristics of spatters during high-power disk laser welding
Authors: Gao Xiang-Dong  , Long Guan-Fu  , Wang Run-Lin  , Katayama Seiji  ,   Faculty of Mechanical and Electrical Engineering, Guangdong University of Technology, Guangzhou 510006, China;,   Joining and Welding Research Institute, Osaka University, Osaka 567-0047, Japan
Published: December 2020

Real-time monitoring and control of welding process is important for laser welding quality. Therefore, the variation rule of sensing characteristics of welding process and their relations to weld quality should be known. Spatter is one of the most important phenomena in high-power laser welding process. The characteristics of spatters are related to the quality and stability of welding and the utilization of the laser power. An approach to analyze the characteristics of spatters is investigated during high-power disk laser bead-on-plate welding of Type 304 austenitic stainless steel plates at a continuous wave laser power of 10 kW. An ultraviolet and visible sensitive high-speed video camera is used to capture the dynamic images of the laser welding spatters. The number, area, and ejecting distance of spatters and the centroid height of spatter images are calculated as the characteristic parameters of spatters by using the image processing technology. The weld bead width is considered as a parameter reflecting the quality and stability of welding process. The linear and the higher order polynomial curve fitting for the data of the characteristic parameters are used to study the variation rule of the characteristic parameters of spatters. In comparison of the fluctuation of the weld bead width, the correlation between the spatter characteristics and the quality and stability of welding is studied. The experimental results of actual laser welding show that the quality and stability of a high-power disk laser welding of Type 304 austenitic stainless steel plates could be monitored and estimated by analyzing the characteristic parameters of spatters, which is the foundation for monitoring and control of welding quality in real time.
Coherent excitation and control of Rydberg lithium atoms in a chirped microwave field
Authors: Jiang Li-Juan  , Zhang Xian-Zhou  , Jia Guang-Rui  , Zhang Yong-Hui  , Xia Li-Hua  ,   Department of Physics, Henan Normal University, Xinxiang 453007, China;,   Department of Physics and Electronic Engineering, Xinxiang University, Xinxiang 453003, China
Published: December 2020

The time-dependent multilevel approach (TDMA) and the B-spline expansion technique are used to study the properties of Rydberg lithium atom. The energy level structures of high excited states n = 7075, l = 05 and population transfer of lithium atom in a microwave field are studied by numerical calculation. The results show that the coherent control of the population transfer in microwave field from the initial to the target states can be accomplished by optimizing the microwave field parameters. and that each state plays a crucial role in the transition process.