bluuebunny/crossref_metadata_2025 huggingface dataset:
Study of electron spin diffusion transport in intrinsic GaAs quantum wells by time- and space-resolved absorbtion spectroscopy
Authors: Yu Hua-Liang  , Zhang Xiu-Min  , Teng Li-Hua  , Wen Jin-Hui  , Lin Wei-Zhu  , Lai Tian-Shu  ,   中山大学光电材料与技术国家重点实验室,物理科学与工程学院,广州  510275
Published: December 2020

A time- and space-resolved circularly polarized pump-probe spectroscopy and its theory are developed, and are used experimentally to study electron spin diffusion transport in intrinsic GaAs quantum wells. The ambipolar spin diffusion coefficient of Ｄas=37.5±15 cm2/s is obtained at room temperature, and is smaller than that in a doped GaAs quantum well obtained by spin grating. The difference is explained based on “hole Coulomb drag" effect which slows the diffusion transport of electron spin packet.
The electron dynamics of semimetal Sb films
Authors: Chen Yu-Hui  , Wang Yang  , Zuo Fang-Yuan  , Lai Tian-Shu  , Wu Yi-Qun  ,   (1)中国科学院上海光学精密机械研究所，中国科学院强激光材料科学与技术重点实验室，上海  201800; (2)中山大学物理科学与工程技术学院,光电材料与技术国家重点实验室,广州  510275
Published: December 2020

The time resolved pump-probe spectroscopy was used to study the ultrafast carrier dynamics of semimetal Sb films at different wavelengths and pump fluences. The profiles of differential transmission versus delayed time showed sharp oscillation near the zero-time_delayed point. A positive absorption saturation peak turned into a negative absorption peak in subpicosecond time. Then the latter began to attenuate and again showed absorption saturation eventually in several picoseconds. The amplitudes of the positive and negative peaks were proportional to the pump fluence and wavelength. These phenomena are analyzed in this article and explained reasonably and semi-quantitatively by introducing the “defect model" and considering fast capture and release by “defect states" of hot electrons.
Use of Monte Carlo simulations for the scatter events analysis of PET scanners
Authors: Gao Fei  , Ryoko Yamada  , Mitsuo Watanabe  , Liu Hua-Feng  ,   (1)日本滨松光子学株式会社中央研究所,滨松,日本  434-8601; (2)浙江大学现代光学仪器国家重点实验室,杭州  310027
Published: December 2020

Monte Carlo simulation is an essential tool to assist in the design of new medical imaging devices for emission tomography. This paper modeled the full 3D whole body PET scanner and 2D animal PET scanner with septa using Monte Carlo simulation code GATE based on Geant4, analyzed the scatter fraction, scatter distribution, multiple scatter events, and scatter events from outside of FOV under 3D acquisition mode and scatter events from the septa under 2D acquisition mode. For the critical problems of 3D scatter correction: multiple scatter events and scatter events from outside of FOV, we designed additional experiments, got the fitted relationship between the percentage of multiple scatter events and the cross sectional area of the phantom, and the effects of the scatter events from outside of FOV at different ring positions; for the 2D scatter correction, we separated the scatter events from septa for analysis, and provided a quantitative reference for the elimination of these events or introduction into the procedure of reconstruction.
Analysis of synchronization in the varying-period slow-wave structures
Authors: Xu Ao  , Wang Wen-Xiang  , Wei Yan-Yu  , Gong Yu-Bin  , Wang Zhan-Liang  , Fu Cheng-Fang  , Yin Hai-Rong  ,   电子科技大学物理电子学院,大功率微波电真空器件技术重点实验室,成都  610054
Published: December 2020

To utilize the interaction between the field and the electron beam in a traveling wave tube （TWT）, the velocity of electrons and the longitudinal phase velocity of field should be made approximately equal. But when the electromagnetic energy increases, the electrons are slowed down and the synchronization condition is no longer satisfied in periodic structures. However, the varying-period slow-wave structure can be used to maintain the synchronization in the whole interaction section. This structure also has the advantages of space harmonic selectivity and wide bandwidth. The space harmonic in varying-period slow-wave structures is analyzed here. The synchronization condition of one space harmonic with the electron beam during the whole interaction process is presented in this paper. And the folded waveguide with varying period is analyzed as an example.
Stochastic collocation method for interconnect delay estimation in the presence of process variations
Authors: Li Xin  , Wang Janet M.  , Tang Wei-Qing  ,   (1)南京理工大学计算机科学与技术学院，南京  210094; (2)亚利桑那大学电子工程系，美国亚利桑那州  AZ8742; (3)中国科学院计算技术研究所，北京  100190
Published: December 2020

We present a process variations based stochastic collocation method to estimate interconnect delay. This method translates the strongly correlated process variations into orthogonal random variables by Cholesky decomposition. Polynomial chaos expression （PCE） and stochastic collocation method （SCM） are used to analyse the system response. A finite representation of interconnect delay is then obtained by using the collocation approach of minimizing the Hilbert space norm of the residual error. Experiment demonstrates that results obtained from the analysis method agree well with that from HSPICE simulation. The difference between the delays obtained from the analytical method and that from HSPICE is about 0.2% or less. Moreover, the method shows good computational efficiency, and much less running time has been observed compared with HSPICE simulation.
A kind of conserved quantity of Mei symmetry for Lagrange system
Authors: Fang Jian-Hui  ,   中国石油大学物理科学与技术学院，东营  257061
Published: December 2020

A kind of conserved quantity which is directly induced by Mei symmetry of Lagrange system is studied. The definition and criterion of Mei symmetry for Lagrange system are given. The condition under which Mei symmetry can lead to a conserved quantity and the form of the conserved quantity are obtained. An example is given to illustrate the application of the result.
Acceleration-dependent Lagrangians in classical mechanics
Authors: Ding Guang-Tao  ,   安徽师范大学物理与电子信息学院，芜湖  241000
Published: December 2020

The linear acceleration-dependent Lagrangians are studied. Under the symmetric conditions of coefficients in acceleration terms, the Lagrange's equations remain second-order differential equations. The approach to constructing an acceleration-dependent Lagrangian from its equations of motion is presented. The relations between the acceleration-dependent Lagrangians and the acceleration independent ones of the same system are studied. Two examples are given to illustrate the application of the results.
The Lie symmetry and Noether conserved quantity of discrete difference variational Hamilton system
Authors: Shi Shen-Yang  , Huang Xiao-Hong  , Zhang Xiao-Bo  , Jin Li  ,   (1)温州大学物理与电子信息学院,温州  325000; (2)浙江理工大学物理系,杭州  310018
Published: December 2020

The Lie symmetry and Noether conserved quantity of discrete difference Hamilton system are investigated. Based on the extended mechanical variational principle of discrete time, the difference dynamical equations of Hamilton system are constructed. The invariance of difference equations of discrete system under infinitesimal transformation groups is defined to be Lie symmetry and the criterion for when discrete Noether conserved quantities may be obtained from Lie symmetries is also deduced. An example is discussed to show the applications of the results.
Ion acceleration by shock wave induced by laser plasma interaction
Authors: He Min-Qing  , Dong Quan-Li  , Sheng Zheng-Ming  , Weng Su-Ming  , Chen Min  , Wu Hui-Chun  , Zhang Jie  ,   (1)北京凝聚态物理国家实验室，中国科学院物理研究所，北京  100190; (2)北京凝聚态物理国家实验室，中国科学院物理研究所，北京  100190；上海交通大学物理系，上海  200240
Published: December 2020

The structure of the collisionless electrostatic shockwave (CES) and the process of the ion acceleration by shock wave are investigated with a series of two dimensional particle-in-cell (PIC) simulations. It is found that only ions satisfying some criteria can be accelerated due to the bipolar electric field in the shock wave front. A comparative investigation of the ion acceleration process by shock wave and solitary wave has been made. Only ions located in the sheath can be accelerated by the solitary wave. We also compare the shock wave for different laser intensities and different plasma densities. The ion energy spectrum of the shock wave has a platform. It can be used to ignite as the ignition material.
Spread dynamics of infectious disease in growing scale-free networks
Authors: Ni Shun-Jiang  , Weng Wen-Guo  , Fan Wei-Cheng  ,   (1)清华大学工程物理系，公共安全研究中心，北京  100084; (2)清华大学工程物理系，公共安全研究中心，北京  100084；清华大学航天航空学院，北京  100084
Published: December 2020

Some fundamental social structures in human population, such as household, dormitory, and colleague, are of significant importance for epidemic spreading. In this paper, a growth model of scale-free network incorporating these local structures is introduced, in which both the node degree and the local structure degree follow a power-law distribution with the exponent depending on the size of the local structure. The existence of the local structures also results in the positive correlation between the nodes degree, which is a particularly key feature of social networks. By means of analysis and simulation, we study the effects of network structure on the SIS（susceptible-infected-susceptible） epidemic dynamics, and obtain the epidemic threshold and the phase diagram of prevalence, indicating that the propagation is coupled by the local infection process within local structure and the global infection process between local structures, both of which are governed by the network features and the transmission mechanism. These results are of scientific significance to the control of infectious diseases.
Cascading failures on complex networks based on the local preferential redistribution rule of the load
Authors: Wang Jian-Wei  , Rong Li-Li  ,   大连理工大学系统工程研究所，大连  116024
Published: December 2020

Cascading failures are common in real-life networks. To better explore the robustness against cascading failures on complex networks，by adopting the initial load of a node j to be Lj=kαj，where kj is the degree of the node j，a new cascading model is proposed based on the local preferential redistribution rule of the broken node's load. According to a new measure to the robustness of a network，we further investigate cascading failures on four typical networks. The numerical simulations show that four networks reach the strongest robustness level against cascading failures and that the robustness against cascading failures on four networks has a negative correlation with the average degree 〈k〉 when α=1. The simulation results are also verified by the theoretical analysis.
The twofold influence of non-periodic force on chaos control
Authors: Yang Xiao-Li  , Xu Wei  ,   (1)陕西师范大学数学与信息科学学院，西安  710062；西北工业大学应用数学系，西安  710072; (2)西北工业大学应用数学系，西安  710072
Published: December 2020

The influences of a kind of non-periodic force，modeled by bounded noise or chaotic driving，on chaos control of nonlinear dynamical system are studied. Suppressing chaos as well as inducing chaos in a periodically driven Duffing-van der Pol oscillator with 5 nonlinear components is studied in detail. By examining the separation distance，the largest Lyapunov exponent，the scaling exponent of power spectrum, and the Poincar map of the considered oscillator，it is found that the non-periodic driving of appropriate amplitude，on one hand，can eliminate the sensitive dependence on initial conditions，then suppress the chaotic behavior and convert a chaotic attractor to a strange but nonchaotic one in this DVP oscillator. On the other hand，it can induce the chaotic behavior and then convert a periodic attractor to a chaotic one as well. Thus，the dual roles of non-periodic driving，i.e. suppressing and inducing chaos，in chaos control of nonlinear dynamical systems are revealed.
Adaptive projective synchronization and parameter identification of Takagi-Sugeno fuzzy hyperchaotic systems
Authors: Wang Xing-Yuan  , Meng Juan  ,   大连理工大学电子与信息工程学院，大连  116024
Published: December 2020

The projective synchronization problems of uncertain hyperchaotic systems is investigated. Based on the Takagi-Sugeno （T-S） fuzzy model，an adaptive controller and the parameter update rule are designed. The feasibility of the proposed scheme is verified according to Lyapunov stability theory. Using the designed controller，parameters identification and the projective synchronization of uncertain hyperchaotic systems can be achieved simultaneously. Hyperchaotic Lorenz system is employed to illustrate the effectiveness of the proposed scheme.
Luminescence properties and upconversion of Er3+ doped and Er3+/Yb3+ co-doped LaF3 particles
Authors: Xiao Si-Guo  , Yang Xiao-Liang  , Ding Jian-Wen  ,   湘潭大学材料与光电物理学院，湘潭  411105；湘潭大学纳米物理与稀土发光研究所,湘潭  411105
Published: December 2020

Er3+ doped and Er3+/Yb3+ co-doped superfine LaF3 powders are prepared using co-precipitation method. The sample shows spherical particles with size of about 250 nm. The quantum efficiencies of 4S3/2 and 4F9/2 levels in the prepared Er3+ doped LaF3 powders are calculated to be 67.0% and 71.9%, respectively. With the enhancement of the Yb3+ doping concentration, The upconvertion intensity increases as a function of excitation power more slowly due to the enhancement of the sensitization of Yb3+ to Er3+. The Er3+-Er3+ interaction is also reinforced as the Yb3+ concentration increases. This leads to the increase of the ratio of the green emission to the red one with the enhancement of Yb3+ concentration.
A method for magnetic field prediction caused by naval vessels using magnetic charge distribution
Authors: Chen Jie  , Lu Xi-Wen  ,   华东理工大学理学院,上海  200237
Published: December 2020

From the viewpoint of equivalent sources, the ferromagnetic hull of naval vessels is regarded as a magnetic charge layer, and a Fredholm integral equation of the first kind relating the layer with the measurements of magnetic field sensors is developed. After the discretization of the integral equation, a system of linear equations is obtained which is solved by generalized inverse matrix, and the condition number is employed to assess whether the system is ill-posed. Then the field caused by the hull at an arbitrary point in the space is predicted by the calculated layer. A numerical simulation shows that our method can precisely identify the magnetization to predict the field. And finally a ship model is used to verify the method.
Three-dimensional numerical modeling of marine controlled-source electromagnetic responses in a layered anisotropic seabed using integral equation method
Authors: Chen Gui-Bo  , Wang Hong-Nian  , Yao Jing-Jin  , Han Zi-Ye  ,   (1)吉林大学物理学院，长春  130021; (2)中国地质科学院地球物理地球化学勘察研究所，廊坊  065000
Published: December 2020

We perform a numerical simulation of marine controlled-source electromagnetic （MCSEM） responses in a layered anisotropic seabed using integral equation method. Firstly, we use the operator theory to deduce the contraction integral equation, which is always convergent regardless of any parameters, for it satisfies the contraction mapping condition. Then we introduce the subdomain multigrid and quasi-linear approximation to improve the computation efficiency. We also validate the accuracy and efficiency of the algorithm by synthetic numerical modelings. Finally, we simulate the three-dimensional MCSEM responses in the layered anisotropic seabed, and investigate the effects of anisotropy.
Study of Nd3+-doped polarization maintaining fiber amplifier
Authors: Ren Guang-Jun  , Wei Zhen  , Zhang Qiang  , Yao Jian-Quan  ,   (1)天津大学精密仪器与光电子工程学院，激光与光电子研究所，光电信息科学技术教育部重点实验室,天津  300072; (2)天津理工大学电子信息与通信工程学院，薄膜电子与通信器件天津市重点实验室，通信器件与技术教育部工程研究中心，天津  300191
Published: December 2020

The distribution of pump light and signal light power of Nd3+-doped fiber amplifier along the fiber is numerically simulated. The Nd3 +-doped polarization-maintaining fiber amplifier is experimentally studied, which is pumped by 808nm semiconductor laser. The enlargement factor of small-signal is 300（the gain is 25dB）, and the steady 5W amplificatory pulse is obtained by using the self-made Nd:YAG passive mode-locking laser as seed source. The 86142B-type spectrograph and TDS5104 oscillograph are employed to detect the output laser, and the output power is measured by power meter.
Synthesis of metallic nanoparticles in spinel via defects induced by the inert-gas-ion implantation
Authors: Yang Yi-Tao  , Zhang Chong-Hong  , Zhou Li-Hong  , Li Bing-Sheng  , Zhang Li-Qing  ,   (1)中国科学院近代物理研究所，兰州  730000; (2)中国科学院近代物理研究所，兰州  730000；中国科学院研究生院，北京  100049
Published: December 2020

Spinel specimens deposited with a thin heavy metal (Cu，Au) film were implanted with inert-gas-ions and annealed in vacuum subsequently. The surface-plasmon-resonance-absorbance peak corresponding to metallic nanoparticles in the dielectric matrix was observed in the ultraviolet-visible absorbance spectra，indicating metallic nanoparticles were formed in the spinel specimens. The influence of the thickness of the metallic film deposited on the spinel specimen surface on the nanoparticle formation is evident besides the effect of annealing temperature.
The transformation between the third-order Eulerian and Lagrangian solutions for irrotational progressive gravity waves
Authors: Hsu Hung-Chu  , Chen Yang-Yih  ,   (1)成功大学水工试验所，台南 701; (2)中山大学海洋环境及工程学系，高雄 807
Published: December 2020

This study reports the transformation between the third-order Eulerian and Lagrangian solutions for the progressive water gravity waves propagating on water of uniform depth. Regarding to the motion of a marked fluid particle, the instantaneous velocity, mass conservation and free surface must be the same for solufions of either Eulerian or Lagrangian method. Using a successive Taylor series expansion to the path and the period of particle motion, the given conventional Eulerian solutions can be transformed into the completely unknown Lagrangian solutions and the reversible process is also identified. In the asymptotic solution, the explicit parametric equation of water particles can be obtained. In particular, the Lagrangian mean level and the Lagrangian wave frequency which differ from those in the Eulerian approach are found as part of the solutions. It shows that the present technique provides a modified method to obtain the third-order Lagrangian solution from the known Eulerian solutions.
Finite segment method for calculating the shear lag in thin-walled curved box girders
Authors: Wu You-Ming  , Yue Zhu-Feng  , Lü Zhen-Zhou  ,   (1)佛山大学数学系,佛山  528000; (2)西北工业大学工程力学系,西安  710072
Published: December 2020

The homogeneous solutions to the governing difference equations derived from energy variational method were used as the displacement patterns of finite segment. A finite segment model considering the initial curvature, bending,torsion,shear lag and distortion was established. The stiffness matrix and load column matrix were obtained based on the directed stiffness method and the working energy principle. A finite segment method was presented to calculate the shear lag effects with multi-span continuous curved box girder generally used in engineering. A perspex glass model of a two-span continuous curved box girder was made.The test on the perspex model were performed to study the shear lag effects respectively under concentrated load and uniformly distributed load. The calculation results of finite segment method were in agreement with the experimental results and results of finite element method, which verifies the accuracy of the finite segment method.
The effect of surface tension on bubble oscillation near a rigid boundary
Authors: Liu Xiu-Mei  , He Jie  , Lu Jian  , Ni Xiao-Wu  ,   (1)南京工程学院基础部, 南京  211167; (2)南京理工大学应用物理系,南京  210094
Published: December 2020

The surface tension of a liquid is one of the basic factors determining cavitation and cavitation erosion. The expansion and contraction of cavitation bubble in liquids with different surface tensions are investigated experimentally, which are compared with theoretical analyses based on Rayleigh-Plesset equation. In the experimental study, cavitation bubble is induced by a laser pulse, the spatial evolution and velocity of the bubble wall in liquids with different surface tensions are detected by a fiber-optic diagnostic technique based on optical beam deflection. Experimental results show that the surface-tension forces hinder the bubble growth progress, so increasing surface-tension decreases the maximum bubble radii. On the other hand, the surface-tension forces speed up bubble collapse process. In larger surface tension cases, the bubble velocity is higher, and higher erosive power is produced.
Creep behavior of a Fe-based bulk amorphous alloy using nanoindentation
Authors: Peng Jian  , Long Zhi-Lin  , Wei Hong-Qing  , Li Xiang-An  , Zhang Zhi-Chun  ,   湘潭大学土木工程与力学学院，湘潭  411105
Published: December 2020

The creep behavior of a {［（Fe0.6Co0.4）0.75B0.2Si0.05］0.96Nb0.04}96Cr4 bulk amorphous alloy and effects of different loading rates on its creep deformation behavior were investigated using nanoindentation technique at room temperature. It is found that the creep deformation of this alloy is strongly dependent on the indentation loading rate: when the loading rate ranges from 3 to 24 mN/s, distinct creep deformation occurs; but when the loading rate decreases to 1 mN/s or 0.75 mN/s, the creep deformation is completely suppressed. The creep deformation behavior of the {［（Fe0.6Co0.4）0.75B0.2Si0.05］0.96Nb0.04}96Cr4 bulk amorphous alloy was modeled using the elastic-viscoelastic-viscous （EVEV） model and a high correlation coefficient （R） of 0.9392 was obtained, implying that this creep behavior studied can be well described by the EVEV model. Based on the EVEV model, the creep compliance and retardation spectrum, which are related to the interior structure of the bulk amorphous alloy, were further calculated by the EVEV model. Finally, the creep mechanism at room temperature was discussed in detail according to the analysis of the creep rate sensitivity index （m） as well as the observation on the morphology of indents using the atomic force microscope （AFM）.
Molecular-dynamics simulation of the structure and elastic constants of barium titanium
Authors: Chen Yu-Xiang  , Xie Guo-Feng  , Ma Ying  , Zhou Yi-Chun  ,   湘潭大学材料与光电物理学院，低维材料及其应用技术教育部重点实验室，湘潭  411105
Published: December 2020

An effective interatomic potential is crucial for molecular dynamics simulations. A more effective potential is proposed. One of the characteristics of this potential is the introduction of the parameter reff to calculate the electrostatic interactions among atoms. The pair-correlation functions and X-ray diffraction patterns of cubic and tetragonal Barium Titanium are derived from molecular-dynamics simulations with the use of the new potential function. Lattice constants and elastic constants are also calculated. The calculated results agree well with the experimental data, which suggests that this potential is promising in describing the thermodynamic or mechanic properties of Barium Titanium.
The effect of nonlinear parameters in one-dimensional mixed Klein-Gordon/Fermi-Pasta-Ulam chain
Authors: Zhou Qian  , Lü Bin-Bin  , Tian Qiang  ,   北京师范大学物理系，北京  100875
Published: December 2020

The possible discrete breathers are obtained numerically in the system of one-dimensional mixed Klein-Gordon/Fermi-Pasta-Ulam chain on the basis of simplified motion equations by using extended rotating plane wave approximation. Furthermore，the effect of each nonlinear parameter on the static，first-order harmonic and second-order harmonic components of the discrete breathers is investigated.
Spin-dependent transport through a closed Aharonov-Bohm interferometer coupled to ferromagnetic electrodes
Authors: Wu Shao-Quan  ,   四川师范大学物理与电子工程学院,成都  610068
Published: December 2020

Using the Keldysh nonequilibrium Green function and equation-of-motion technique, we investigate the spin-dependent transport through a closed Aharonov-Bohm interferometer coupled to ferromagnetic leads. With the Fano factor, We analyse the effect of the Fano and the Kondo resonance on the conductance and the variation of the conductance with the spin-polarization strength and the magnetic flux in both the parallel and the antiparallel lead-polarization alignments. Our results show that the conductance can be controlled effectively by the spin-polarization strength and the magnetic flux, while the line shapes of the conductance depend mainly on the magnetic flux and that a large tunneling magnetoresistance and a negative tunneling magnetoresistance can arise by adjusting the relative parameters. This system is a possible candidate for spin valve transistors and is of potential applications in the spintronics.
Cellular neural network with hybrid single-electron and MOS transistors architecture and its application
Authors: Li Qin  , Cai Li  , Feng Chao-Wen  ,   空军工程大学理学院，西安  710051
Published: December 2020

Based on both the cell equivalent circuit of cellular neural network and the electrical characteristic model of cellular neural networks（CNN） cell，the cell circuit of cellular neural networks is implemented. The activation function of cell circuit is made of two cascaded SET-MOS inverter, which is proposed previously by the author. The CNN cloning template is built by coupling capacitance of input terminal. Then the CNN and its application in image processing are built and studied. The computer simulation results show that the designed circuits is suitable for CNN implementation because of its simple structure, low power dissipation and fast response. The designed circuit can be used to form CNN of various scales so as to further satisfy the need of large-scale signal processing and improve the density of integrated circuit.
High temperature superconducting filter with linear phase on LaAlO3 substrates
Authors: Zuo Tao  , Zhao Xin-Jie  , Wang Xiao-Kun  , Yue Hong-Wei  , Fang Lan  , Yan Shao-Lin  ,   (1)南开大学电子系，天津  300071; (2)中国人民解放军68612部队，宁夏  750021
Published: December 2020

A linear phase high temperature superconducting （HTS） filter fabricated on LaAlO3 substrates is presented. The designed passband of the HTS filter is 10 MHz and the group delay ripples over 80% of the passband is less than 20 ns. The filter consists of novel resonators, which are able to minimize the spurious couplings between resonators. As a result, the filter shows not only the linear phase characteristic but also the symmetrical frequency response. The measured passband is 9.85 MHz. The return loss is better than 16 dB and the out-of -band rejection is better than 80 dB. The measured group delay ripples is about 20 ns, which is in good agreement with the simulated result.
Fabrication and characterization of La0.7Sr0.3MnO3 sandwich structure separated by （La0.7Sr0.3MnO3）m（BiFeO3）n superlattice
Authors: Wang Jun-Wei  , Zhang Yong  , Jiang Ping  , Tang Wei-Hua  ,   浙江理工大学光电材料与器件中心,杭州\ 310018
Published: December 2020

The La0.7Sr0.3MnO3 sandwich structure separated by （La0.7Sr0.3MnO3）m（BiFeO3）n superlattices is grown in situ on SrTiO3（001） substrates by RF magnetron sputtering. The X-ray diffraction scans indicate that the films are obviously superlattice structures. The resistivity-temperature curves measured in the case of current perpendicular to the plane geometry show that the films undergo metal-insulator transition at 290 K, which is a little lower than the temperature of single La0.7Sr0.3MnO3 film. When the current is within 0.01—10 mA, the peak resistivity of the （La0.7Sr0.3MnO3）m（BiFeO3）n films decreases with the increasing current.The change rate which is higher than that of single La0.7Sr0.3MnO3 film increases with the increasing thickness of the period films. The current-voltage curves indicate that the conduction mechanism in superlattices is space-charge-limited con-duction and a big bias voltage which is a characteristic of Schottky junction is also found in the current-voltage curves at low temperatures.
ESR characteristics of high-quality semi-insulating 4H-SiC crystal prepared by LPCVD
Authors: Cheng Ping  , Zhang Yu-Ming  , Guo Hui  , Zhang Yi-Men  , Liao Yu-Long  ,   西安电子科技大学微电子学院，宽禁带半导体材料与器件教育部重点实验室，西安  710071
Published: December 2020

By using electron spin resonance （ESR）, the intrinsic defects in high-quality semi-insulating 4H-SiC prepared by low pressure chemistry vapor deposition （LPCVD） are investigated. In dark-field condition, the results show that the defects have the characteristics of VC and its complex compounds, while the absorption spectra are obviously asymmetry and have wider ESR half-width. The asymmetric chart and the wider ESR half-width are attributed to the higher testing temperature, non-homogeneous distribution of the defect concentration and the unsymmetrical crystal structure in 4H-SiC. The distributions of electrons have little effect on the ESR characteristic at the testing temperature of 110 K.
Photoluminescence properties of Ge-doped silica glass
Authors: Wang Xing-He  , Zhou Yan-Huai  ,   南京师范大学物理科学与技术学院，南京  210097
Published: December 2020

Ge crystals doped in SiO2 glassy materials were formed by heating GeO2/SiO2 glass at 700 ℃ in the presence of hydrogen. The GeO2/SiO2 glass was prepared by the sol-gel technique. The Ge/SiO2 samples showed a special photoluminescence property to give off strong room temperature luminescence at 392 nm（3.12 eV）, secondary strong luminescence at 600 nm（2.05 eV）,and weak luminescence at 770 nm（1.60 eV）, when excited by 246nm （5.01 eV） ultra-violet light. The structure of this new luminescence material was studied by XRD, XPS, and TEM techniques. The results show that the existences of nanometer-sized （around 10 nm） Ge and GeO crystals in the SiO2 may cause the three band photoluminescence property. As a comparison, there is only GeO2 in SiO2 glass before the heating plus reducing process, and the photoluminescence property is not found.
Optimization of high rate growth high quality μc-Si:H thin films and its application to the solar cells
Authors: Han Xiao-Yan  , Hou Guo-Fu  , Wei Chang-Chun  , Zhang Xiao-Dan  , Dai Zhi-Hua  , Li Gui-Jun  , Sun Jian  , Chen Xin-Liang  , Zhang De-Kun  , Xue Jun-Ming  , Zhao Ying  , Geng Xin-Hua  ,   南开大学光电子薄膜器件与技术研究所，光电子薄膜器件与技术天津市重点实验室，光电信息技术科学教育部重点实验室，天津  300071
Published: December 2020

A series of high rate growth μc-Si:H thin films with different thicknesses were deposited by very high frequency plasma enhanced chemical vapor deposition （VHF-PECVD） process with high power and high pressure. The microstructure of the μc-Si:H thin films was studied by the Raman and XRD spectra. It was found that the crystal fraction and grain size increased with the thickness of the thin film when the thickness was less than 1000 nm, and then came to saturation when the thickness was higher than 1000 nm. However, the performance of solar cells decreased obviously when the thickness increased from 1000 nm to 2000 nm. Considering the microstructure properties and the ion bombardment during the high rate process, we investigated the controlled microstructure evolution and the improved material quality by discharge power profiling, which improved the performance of solar cells. By optimizing the profiling parameters, such as the amount and the rate of change in discharge power, a high efficiency of 9.36% was obtained with an i-layer deposition rate of 1.2 nm/s. Furthermore, we used the improved μc-Si:H cell in an a-Si:H/μc-Si:H double-junction structure and achieved an initial active-area cell efficiency of 1114%.
Synchrotron radiation angle-resolved photoelectron spectroscopy studies of 6H-SiC（0001）-6[KF（]3[KF）]×6[KF（]3[KF）] R30° surface
Authors: Wu Yu-Yu  , Chen Shi  , Gao Xin-Yu  , Andrew Thye Shen Wee  , Xu Peng-Shou  ,   (1)新加坡国立大学物理系,117542  新加坡; (2)中国科学技术大学国家同步辐射实验室，合肥  230029
Published: December 2020

The electronic structure including some surface states of the 6[KF（]3[KF）]×6[KF（]3[KF）] R30° reconstructed 6H-SiC（0001） surface have been investigated by synchrotron radiation angle-resolved photoelectron spectroscopy （SRARPES）. The energy position of the bulk valence band maximum （VBM） is determined to be at （-2.1±0.1） eV related to the Fermi level by identifying bulk states from valence band spectra. The experimentally measured bulk energy band structure agrees well with the theoretical calculation result. Three surface states are clearly identified at the binding energies of -0.48 eV （S0）, -1.62 eV （S1） and -4.93 eV （S2） referred to the Fermi level. The surface state dispersion is measured along ΓKM, the high symmetry lines of the surface Brillouin zone. Only surface state S0 （-0.48 eV） shows expected 6[KF（]3[KF）]×6[KF（]3[KF）] R30° periodicity in all probed SBZ. Surface state S0 should be attributed to the C—C dangling bonds of the surface reconstruction. Surface states S1 should be attributed to the unsaturated C dangling bonds.
Preparation of large area CdS thin film and its application in photovoltaic cells
Authors: Cai Ya-Ping  , Li Wei  , Feng Liang-Huan  , Li Bing  , Cai Wei  , Lei Zhi  , Zhang Jing-Quan  , Wu Li-Li  , Zheng Jia-Gui  ,   四川大学材料科学与工程学院，成都  610064
Published: December 2020

In this paper，large area CdS thin film was prepared by chemical bath deposition (CBD). The structure and morphology and optical characteristics of the thin film were investigated with XRD，optical transmittance spectra analyzer and AFM. The experimental results indicate that the properties of the thin film were homogeneous. The CdTe solar cells with different thickness of window layer by using the prepared CdS thin film were fabricated. It was found that the short circuit current density，Jsc，of the CdTe solar cells increases with the reduction of the thickness of CdS window layer and the device performance is improved. The module of CdTe solar cells with substrate size 30cm×40cm and total area of 993.6cm2 was fabricated. The results showed that the electrical behaviors of the 27 interconnected unitc were homogeneous too. The efficiency of greater than 8% for the module of CdTe solar cells with area of 993.6 cm2 was obtained.
Nonlinear feedback control of Hopf bifurcation in a relative rotation dynamical system
Authors: Liu Shuang  , Liu Bin  , Shi Pei-Ming  ,   (1)燕山大学电气工程学院，秦皇岛  066004; (2)燕山大学工业计算机控制工程河北省重点实验室，秦皇岛  066004；燕山大学电气工程学院，秦皇岛  066004
Published: December 2020

The Hopf bifurcation characteristic in a relative-rotation dynamical system with nonlinear damping force is analyzed and the necessary and sufficient condition of Hopf bifurcation is given under which the system has Hopf bifurcation emerging from the equilibrium. In order to make the Hopf bifurcation point transformed and control the stability and amplitude of limit cycle，a nonlinear feedback controller is proposed. The analytical results on controlling Hopf bifurcation points via the nonlinear controller agree well with the numerical results.
One-dimensional traffic cellular automaton model with consideration of the change of driving rules
Authors: Kang Rui  , Peng Li-Juan  , Yang Kai  ,   四川大学计算机学院图形图象研究所,成都  610064
Published: December 2020

Based on the WWH and SDNS cellular automata （CA） traffic model, an improved single lane traffic CA model with consideration of the change of driving rules is proposed. The model considers the drivers adopting different driving rules under mutative traffic condition, and introduces the rules of driving method change. Numerical simulations have been carried out. The results show the complicated evolution process of traffic flow. Different values of change probability have different effect on mixed traffic flow. With the increase of change probability, aggressive vehicles cause greater effect. In the evolution process, the change frequency can be controlled by the definition of the change probability and safety probability. The traffic flow is higher in the new model than in the NS and SDNS model. This proves that the stop status of the whole traffic flow has been improved.
Experimental investigation of L-band bifrequency magnetically insulated transmission line oscillator
Authors: Chen Dai-Bing  , Wang Dong  , Fan Zhi-Kai  , Meng Fan-Bao  , An Hai-Shi  , Gong Hai-Tao  , Qin Fen  ,   中国工程物理研究院应用电子学研究所,绵阳  621900
Published: December 2020

Experimental investigation of an L-band bifrequency（BF） magnetically insulated transmission line oscillator（MILO） based on azimuthal partition of cavity-depth, is carried out for the first time. Experimental system and measurement system of the BFMILO are set up. Far-field patterns of the antenna of the L-band BFMILO are obtained, and the total microwave power is obtained by integral of the power density of radiation field. Employing an electron beam of 420kV, 34kA, an L-band BFMILO can generate high power microwave （HPM） with two stable and separate frequencies. They are 1.26GHz and 1.45GHz respectively with power of 398MW and 222MW. Preliminary experimental results of BFMILOs with different azimuthal partition proportion are presented. The investigation proves the feasibility that BFMILO can generate HPM with two stable frequencies, which indicates an L-band BFMILO is developed successfully for the first time. A new direction of HPM investigations is pointed out.
Analysis of a new kind of LTCC cascade multilayer structure by wave concept iterative process
Authors: Feng He  , Xie Yong-Jun  , Wang Yuan-Yuan  , Fu Huan-Zhan  , Lei Fei-Ran  ,   西安电子科技大学,西安  710071
Published: December 2020

In this paper, an efficient new method named wave concept iterative process （WCIP） based on transformation between space domain and spectral domain is introduced. The derived WCIP theory formulation is presented in detail. A new kind of LTCC multilayer structure is analyzed using the iterative method. The approach involves the mixed magnetic and electric field equation and S parameter extraction technique based on a simple form of matched load simulation. The whole process is illustrated by MATLAB programming, so that frequency response of S parameter is determined. The numerical results are compared with the simulation results and good agreement shows the validity and usefulness of the iterative method given in this paper.
The influence of Kerr medium on the intrinsic decoherence under the condition of existence of dipole-dipole interaction
Authors: Qi Lin-Na  , Zhang Shou  ,   延边大学理学院物理系,延吉  133002
Published: December 2020

We investigate the influence of Kerr medium on the concurrence of the two-atom system under the condition of existence of dipole-dipole interaction. The entanglement of the system is calculated by making use of concurrence. We discuss the variation of the concurrence with time. The result shows that the appropriate choice for the nonlinear coupling constant χ of Kerr medium can improve the concurrence of the system and restrain effectively the intrinsic decoherence of the system. We also find that with respect to increasing concurrence, the multiple Λ may take different values as Ω varyies.
Effect of different effective mass and electric field on the electronic structure in GaN/AlxGa1-xN spherical quantum dot
Authors: Wu Hui-Ting  , Wang Hai-Long  , Jiang Li-Ming  ,   曲阜师范大学物理工程学院，曲阜  273165
Published: December 2020

In this paper，we have calculated the impurity electronic states and the binding energy with the variation of the quantum dot radius and Al content in GaN/AlxGa1-xN spherical quantum dot (QD) using the plane wave method. The modification of the energy states is discussed when the difference in effective electron mass in GaN and AlxGa1-xN is taken into account. The results show that the difference in effective mass can not be neglected when Al content is large. In addition，with the consideration of the difference in effective mass，we investigate the binding energy as function of quantum dot radius, impurity position and external electric field. The results are meaningful and can be widely applied in the design of optoelectronic devices.
High power tunable single-frequency 1064 nm quasi-continuous-wave laser oscillator-amplifier system
Authors: Xie Shi-Yong  , Lu Yuan-Fu  , Bo Yong  , Cui Qian-Jin  , Xu Yi-Ting  , Xu Jia-Lin  , Peng Qin-Jun  , Cui Da-Fu  , Xu Zu-Yan  ,   (1)中国科学院理化技术研究所，激光物理与技术研究中心，北京  100190; (2)中国科学院物理研究所，北京凝聚态物理国家实验室，北京  100190；中国科学院理化技术研究所，激光物理与技术研究中心，北京  100190; (3)中国科学院物理研究所，北京凝聚态物理国家实验室，北京  100190；中国科学院研究生院，北京  100190
Published: December 2020

We have developed a high power tunable single-frequency 1064 nm quasi-continuous-wave laser oscillator-amplifier system. By controlling precisely the temperature of etalon in the three-mirror ring traveling-wave oscillating cavity viz. adjusting refractive index and thickness of material to tune laser wavelength, 13.2 W 1064 nm single-frequency quasi-continuous-wave oscillating light with tunable range of 58 GHz is obtained, at repetition rate of 1 kHz and duty ratio of 10%. After the laser beam from the oscillator transfers through the amplifier with two laser heads, the output of the oscillator is amplified to be 44 W and the beam quality factor M2 is measured to be 1.58.
Collinear amplification by dual-beam stimulated Brillouin scattering in a single optical cell
Authors: Chen Xu-Dong  , Shi Jin-Wei  , Ouyang Min  , Liu Bao  , Xu Yan-Xia  , Shi Jiu-Lin  , Liu Da-He  ,   (1)无损检测技术教育部重点实验室,南昌航空大学,南昌  330063; (2)应用光学北京市重点实验室,北京师范大学物理系,北京  100875; (3)应用光学北京市重点实验室,北京师范大学物理系,北京  100875；华南师范大学信息光电子科技学院,广州  510631; (4)应用光学北京市重点实验室,北京师范大学物理系,北京  100875；无损检测技术教育部重点实验室,南昌航空大学,南昌  330063
Published: December 2020

The amplification of the signal of stimulated Brillouin scattering （SBS） is widely used in many area. A method for amplifying the signal of SBS using dual collinear beams in a single optical cell is introduced. The stimulated Brillouin scattering can be induced and amplified in one optical cell. Comparing with previous double-cell technique, the proposed method has the advantages of simple structure and low energy loss. It is necessary for some applications with weak signal of stimulated Brillouin scattering such as lidar for remote sensing, in which double-cell technique is not suitable.
Capillary drawing for fabrication of photonic crystal fibers: theoretical calculation and experiments
Authors: Guo Tie-Ying  , Lou Shu-Qin  , Li Hong-Lei  , Jian Shui-Sheng  ,   (1)全光网络与现代通信网教育部重点实验室,北京  100044; (2)全光网络与现代通信网教育部重点实验室,北京  100044；北京交通大学光波技术研究所,北京  100044; (3)全光网络与现代通信网教育部重点实验室,北京  100045; (4)全光网络与现代通信网教育部重点实验室,北京  100046
Published: December 2020

A simplified fluid-mechanics model is developed for the drawing of silica capillaries. Calculations are carried out to predict the influence of the technical parameters on the final geometry of the capillaries. Geometrical collapse is inevitable when drawing capillaries, and active control of the parameters only helps to some extent in tuning the final structures. Drawing experiments were performed to check the theoretical calcualtions. Good agreement was obtained, which certified the validity of the model. The predictions provide valuable practical information for the fabrication of photonic crystal fibers.
The role of slit in stop band of periodical narrow slit metal tubes
Authors: Cui Zhan-You  , Chen Tian-Ning  , Xu Rui-Qi  , Wu Jiu-Hui  ,   (1)西安交通大学机械学院振动与噪声控制研究所,西安  710049; (2)烟台市东方电子信息产业股份有限公司,烟台  264000
Published: December 2020

The band gap of two-dimensional metal tube structure with multi-width narrow slits is simulated and verified experimentally. The unique properties of the stop band exist in the band gap structure with combined parameters of slit tubes. It is found that the band gap of this structure is large and the starting frequency is low. In contrast to the band gap of the structure with narrow slits, the stop band of the combined structure of the parameters of the slits is continuous and large.
Experimental study on K-shell radiation production of aluminum wire array Z-pinch at Qiangguang-I facility
Authors: Wu Gang  , Qiu Ai-Ci  , Lü Min  , Kuai Bin  , Wang Liang-Ping  , Cong Pei-Tian  , Qiu Meng-Tong  , Lei Tian-Shi  , Sun Tie-Ping  , Guo Ning  , Han Juan-Juan  , Zhang Xin-Jun  , Huang Tao  , Zhang Guo-Wei  , Qiao Kai-Lai  ,   (1)清华大学工程物理系,北京  100084; (2)清华大学工程物理系,北京  100084；西北核技术研究所,西安  710024; (3)西北核技术研究所,西安  710024
Published: December 2020

Experimental study of aluminum wire array Z-pinch was conducted on Qiangguang-I facility （1.5 MA, 80 ns） to produce —1.7 keV characteristic X-ray radiation. With fixed wire diameter of 20 μm and annular diameter of 12 mm, K-shell yield up to 0.9 kJ/cm and 1.1 kJ/cm was obtained for wire number N=8 and N=12 arrays, respectively, which are much higher than that for N=16 and N=24 loads. X-ray power waveforms and time-resolved images showed that several implosions occurred due to the existence of trailing mass. During 60%—80% of the whole implosion time，the wire array almost stayed at its initial position rather than running inwards. Main implosion was completed in the next 25—30 ns, with parts of load mass left behind and forming so-called trailing mass. At later time of main implosion, load current was transferred to trailing mass left in outer radii, and caused secondary even tertiary implosion, which also contributed to total K-shell yield. Appearance of trailing mass might be caused by azimuthally correlated axial modulation, consisting of hot spots and gaps on wire plasma column, as well as the development of other inhomogeneities.
Finite element simulations of thermal-stress on cemented tungsten carbide anvil used in cubic high pressure apparatus
Authors: Han Qi-Gang  , Jia Xiao-Peng  , Ma Hong-An  , Li Rui  , Zhang Cong  , Li Zhan-Chang  , Tian Yu  ,   (1)长春理工大学材料科学与工程学院，长春  130012; (2)吉林大学超硬材料国家重点实验室，长春  130012
Published: December 2020

Based on the theoretical analysis, we performed finite element simulation of high pressure experiment in multi-anvil devices （XKY-6×2000 MN） to determine the temperature and the stress in WC anvil. The simulated results show that the temperature is not uniform, and the ununiform temperature can produce thermal-shear stress in the anvil. The peak value of thermal-shear stress lies on the beveling edge of the anvil, the peak value of thermal-shear stress is 0.62 GPa, which is 18 percent that of unheated anvil. The simulation results have been verified by high pressure synthesis experiment. We developed a new method to simulate the stress of WC anvil at high pressure and high temperature. This would greatly help the design of anvil with safe dimension.
Simulation of evolution mechanisms of microstructures during rapid solidification of Al-Mg alloy melt
Authors: Hou Zhao-Yang  , Liu Li-Xia  , Liu Rang-Su  , Tian Ze-An  ,   (1)长安大学应用物理系，西安  710064; (2)湖南大学应用物理系，长沙  410082; (3)西安电子科技大学理学院，西安  710071
Published: December 2020

The rapid solidification of Al50Mg50 alloy melt has been simulated by using molecular dynamics method, and the evolution mechanism of microstructures at different levels during the rapid solidification process have been deeply studied with the pair distribution function, the bond-type index method and the cluster-type index method. It is demonstrated that the simulated Faber-Ziman partial structure factors are in good agreement with the experimental results. The Al50Mg50 alloy melt possesses heredity. The Al50Mg50 amorphous structure is formed during the rapid solidification process, and the icosahedron short-rang-order structure plays a critical role in the formation of amorphous structure. The atomic cluster analyses based on the cluster-type index method shows that the microstructures of Al50Mg50 amorphous alloy is built from some different types of short-rang-order structures, and the icosahedron is the main short-rang-order structure. There are various cluster structures with different sizes in the short-rang-order regions. But it can not be described with the Bernal model.