bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of grating mosaic error tolerance among three types of laser pulse compressor configurations
Authors: Hu Yao  , Wang Xiao  , Zhu Qi-Hua  ,   School of Optoelectronics, Beijing Institute of Technology, Beijing 100081, China;,   State Key Laboratory of Precision Measurement Technology and Instruments, Tsinghua University, Beijing 100084, China;,   Research Center of Laser Fusion, Chinese Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

Theoretical models of three types (two-pass Z-type, X-type and diamond-type) of laser pulse compressors containing grating mosaics are developed. The corresponding grating mosaic error tolerances are calculated and analyzed with a simulation method adopting ray-tracing phase analysis and Fourier transform. The mosaic error tolerances corresponding to 0.9 of ideal far-field intensity maximum (Strehl ratio equivalent to 0.9) in the case of three types of compressor are determined. The simulation shows different sensitivities of respective compressor configurations to grating mosaic errors,which can help to select the configuration and the design parameters of laser pulse compressor.
Contrast ratio of femtosecond ultraintense Ti:sapphire laser with multi-pass amplifier
Authors: Li Wei-Chang  , Wang Zhao-Hua  , Liu Cheng  , Teng Hao  , Wei Zhi-Yi  ,   Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China;,   Department of Applied Physics, National University of Defense Technology, Changsha 410073, China
Published: December 2020

According to the theory of chirped pulse amplification (CPA), we analyze numerically the gain characteristic of laser pulses in multi-pass amplifier. A CPA Ti:sapphire laser with 10-pass scheme is designed and built. The experimental result shows that the contrast ratio of the femtosecond pulse is obviously enhanced by two orders from 10-5 to 10-7 under a pump flux of 1.6 J/cm2. This work demonstrates that the contrast ratio of the amplified femtosecond laser pulse could be effectively improved by multi-pass preamplifier.
The analysis of transport properties stability in molecular dynamics simulations
Authors: Chen Jun  , Shi Lin  , Wang Nan  , Bi Sheng-Shan  ,   Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Thermal Engineering, Tsinghua University, Beijing 100084, China;,   Key Laboratory of Thermal Fluid Science and Engineering of Ministry of Education, Xi’an Jiaotong University, Xi’an 710049, China
Published: December 2020

The Green-Kubo time correlation function is used to predict fluid argon transport properties, such as diffusion coefficient, viscosity and thermal conductivity, through molecular dynamics simulations. The results show that the transport characteristics, especially the viscosity and thermal conductivity, fluctuate intensely during the simulations. The collective stress tensor is separated into two parts, one is due to the kinetic energy and the other is due to the pair virial function, and the collective heat flux vector is contributed from the kinetic energy, the intermolecular potential and the pair virial function. The results show that the transport characteristics, especially the viscosity and the thermal conductivity, fluctuate intensely during the simulations. The most important contribution to the viscosity and the thermal conductivity is from the autocorrelation of the virial term. The calculations indicate that a more compatible integration time step method is needed to reduce instabilities when the Green-Kubo time correlation is used to calculate the fluid transport parameters. Other factors which influence the stability are also discussed in the paper.
Effect of substrate topography for YBa2 Cu3 O7-x coated conductors on the nucleation mechanism of buffer layer
Authors: Ding Fa-Zhu  , Gu Hong-Wei  , Zhang Teng  , Dai Shao-Tao  , Peng Xing-Yu  , Zhou Wei-Wei  ,   Key Laboratory of Applied Superconductivity, Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190, China
Published: December 2020

The surface condition of substrate tape is an important factor to obtain epitaxial buffer layer on biaxially textured Ni tape for YBa2Cu3O7-x coated conductors. We prepare ceria films on Ni single crystal, biaxially textured Ni tape and sulfured Ni substrates by direct current magnetron sputtering. The results show that the ceria films prepared on Ni single crystal and sulfured Ni substrates each have a poor-textured grain structure. However, the ceria film fabricated on rolling assisted biaxially textured substrate (RABiTS) exhibits a good c-axis texture and desirable surface morphology. Reflection high-energy electron diffraction analysis indicates that the c(22) superstructure on the RABiTS Ni surface has a dramatic effect on the heteroepitaxial growth of oxide buffer layer.
Photoemission mechanism of GaN vacuum surface electron source
Authors: Qiao Jian-Liang  , Chang Ben-Kang  , Qian Yun-Sheng  , Wang Xiao-Hui  , Li Biao  , Xu Yuan  ,   Institute of Electronic Engineering and Optoelectronic Technology, Nanjing University of Science and Technology, Nanjing 210094, China;,   Department of Electronic and Electric Engineering, Nanyang Institute of Technology, Nanyang 473004, China
Published: December 2020

GaN photocathode is fully activated by employing a continuous Cs source and an alternate O source. The quantum efficiency curve of transmission-mode photocathode is tested in situ. The quantum efficiency reaches up to 13% in transmission-mode. According to the one-dimensional Schrdinger equation, the electron transmission coefficient formula of GaN vacuum electron source material is deduced. For a certain profile of photocathode surface potential barrier, the electron transmission coefficient relates to the incident electron energy, the height and the width of the surface potential. The energy band of transmission-mode negative electron affinity (NEA) GaN photocathode and the change of surface barrier in the deposit course of Cs,O are given. Using the double dipole layer surface model [CaN(Mg):Cs]:O-Cs, the NEA property formation of GaN vacuum electron source material is analyzed. The results show that the double dipole layer formed in the activation course of Cs,O is conducible to the escape of electrons, and it is the formation of double dipole layer that causes the drop of vacuum energy level of the material surface.
Energy dissipation of the mixed traffic system with automatic cruise
Authors: Zhu Liu-Hua  , Zheng Rong-Sen  , Tian Huan-Huan  , Wei Yan-Fang  ,   Department of Physics and Information Science, Yulin Normal College, Yulin 537000, China
Published: December 2020

Based on the cellular automaton traffic flow model of automatic cruise controlling, the influences of speed maximum, mixing ratio, expectation factor of speed, and mass of vehicle on energy dissipations of the mixed traffic system are studied. Through computer simulation, the energy dissipations of mixed traffic system under the different parameters are obtained and analysed by the mean field theory. The theoretical analyses are consistent with the results of numerical simulation.
Numerical simulation of RESET operation for multilevel storage in phase change memory cell
Authors: Xie Zi-Jian  , Hu Zuo-Qi  , Wang Yu-Hui  , Zhao Xu  ,   Department of Electronic Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, China
Published: December 2020

The REST operation for multilevel storage in phase change random access memory cell is investigated via numerical simulation. A three-dimensional memory cell model is built, and the physical property variation is calculated by solving the Laplace equation and the heat conduction equation with finite element method. The phase distribution in phase change layer and the total resistance of the cell are examined. The influences of cell structure size variation on multilevel storage process and states are analyzed. The simulation results demonstrate that multilevel storage can be achieved through accurate electrical pulse control while the variations of phase change layer thickness and bottom electrode contact size have relatively large effect on the storage state. The storage states can all keep stable for more than 10 years at 80 ℃.
Synchronization of hyperchaotic systems via improved impulsive control method
Authors: Ma Tie-Dong  , Jiang Wei-Bo  , Fu Jie  , Xue Fang-Zheng  ,   College of Automation, Chongqing University, Chongqing 400044, China;,   Key Laboratory of Optoelectronic Technology and System, Ministry of Education, College of Optoelectronic Engineering, Chongqing University, Chongqing 400044, China
Published: December 2020

The improved impulsive control method is proposed to realize the complete synchronization of integral and fractional order hyperchaotic systems. Some effective sufficient conditions are produced to realize the asymptotical stability of synchronization error system. In particular, some simple and practical conditions are derived in synchronizing the chaotic systems by choosing constant impulsive distances and control gains. Compared with the existing results, the main results are less conservative by relaxing some unnecessary inequality constraints. Simulation results show the effectiveness and the feasibility of the proposed impulsive controller.
The effects of correlated time between noises on stability of unstable state in Logistic system
Authors: Yang Lin-Jing  , Dai Zu-Cheng  ,   College of Chinese Medicine, Yunnan University of Traditional Chinese Medicine, Kunming 650500, China;,   Department of Physics Science and Technology, Kunming University, Kunming 650031, China
Published: December 2020

The effects of correlated time between noises on the stability of unstable state in the Logistic system are investigated. Using the steepest-descent approximation, the analytic expression for the mean first-passage time from unstable state to stable state is derived. The numerically calculated results indicate that the additive noise, the multiplicative noise and the correlated time between the additive and the multiplicative noises weaken the stability of unstable state, but the correlation between the additive and the multiplicative noises enhances the stability of unstable state.
Blackbody-radiation shift in a 199Hg+ ion optical frequency standard
Authors: Liu Li-Hui  , Zou Hong-Xin  , Liu Qu  , Li Xi  ,   Department of Physics, National University of Denfense Technology, Changsha 410073, China
Published: December 2020

The background blackbody radiation causes the shift of the hyperfine energy level and affects the accuracy of the optical frequency standard. The polarizabilities of the hyperfine energy levels 5d106s2S1/2 (F=0) and 5d96s2 2D5/2 (F=2) of 199Hg+ are evaluated and the relative frequency shift at room temperature due to blackboby radiation is calculated to be -5.410-17. Finally the effect of blackbody radiation on single 199Hg+ optical frequency standard is discussed at an ultralow temperature.
Research of subwavelength grating based on multilayer films structure
Authors: Liang Gao-Feng  , Zhao Qing  , Chen Xin  , Wang Chang-Tao  , Zhao Ze-Yu  , Luo Xian-Gang  ,   School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054, China;,   State Key Laboratory of Optical Technologies for Microfabrication, Institute of Optical and Electronics,Chinese Academy of Science, Chengdu 610209, China
Published: December 2020

Based on the theory of suface plasmon resonance and the special nano-optical effect of metal-dielectric composite, we study super-resolution photolithography using multilayer films. The main point is to use 365 nm exposal light to realize super-resolution imaging by using a mask with a period of 230 nm and linewidth of 100 nm. We discuss the selection of the parameters multi-film with equal thickness, and achieve a sufficient contrast and high intensity through numerical simulation, then verify the obtained results by the plasmon nanolithography technique. Choosing the best scheme, we achieve large-area super-resolution images with the subwavelength structure.
First-principles study of nanoscale friction between graphenes
Authors: Wang Jian-Jun  , Wang Fei  , Yuan Peng-Fei  , Sun Qiang  , Jia Yu  ,   School of Physics and Engineering, Center for Energy and Quantum Structures, Zhengzhou University, Zhengzhou 450001, China
Published: December 2020

Using the first-principles calculations within the density functional theory, we study the nanofriction between two graphene layers. The result shows that the friction of the graphene is isotropic, and the relationship between the load and the friction factor can be divided into three phases. For the smaller and larger loads, the friction factor does not increase as the load increases, which follows the Amonton's law; for the middle phase, with the increase of the load, the friction factor increases linearly. However, the nanofriction characteristics between the two incommensurate graphenes show that the incommensurate structure can reduce the friction factor between graphenes greatly, which is in agreement with experimental result. These studies provide a fundamental understanding about the nanofriction phenomenon between the graphene layers.
The influence of Cu on the magnetic and martensitic transformation properties of Ni50Mn36In14
Authors: Liu Zhu-Hong  , Yi Bi  , Li Ge-Tian  , Ma Xing-Qiao  ,   Department of Physics, University of Science and Technology Beijing, Beijing 100083, China
Published: December 2020

In this paper, we investigate the magnetic and martensitic transformation properties of Cu doping partial Ni in Ni50Mn36In14 alloy. It is found that the critical temperature of the martensitic transformation decreases with Cu concentration x in Ni50-xCuxMn36In14 increases. While Cu concentration is less than 5% at., the magnetization of austenite phase is stronger than that of martensite phase, and ΔM of magnetization martensite and austenite increases with Cu doping. ΔM increases rapidly to 80 emu/g when x=4.5 and a field-induced transformation is observed in this alloy, predicting the application potential as the magnetic actuation and magnetoresistance materials. As Cu content increases to x > 5, the magnetization of austenite becomes weaker than that of martnensite, ΔM decreases to near zero.
Preparation and photoelectrochemical properties of multilayer TiO2/CdSe structures
Authors: Li Li-Qun  , Liu Ai-Ping  , Zhao Hai-Xin  , Cui Can  , Tang Wei-Hua  ,   Center for Optoelectronics Materials and Devices, Department of Physics, Key Laboratory of Advanced Textile Materials and Manufacturing Technology of Ministry of Education, Zhejiang Sci-Tech University, Hangzhou 310018, China;,   State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310027, China
Published: December 2020

The red-brown CdSe thin films are electrochemically deposited on conductive ITO/TiO2 film surfaces, and the multilayer TiO2/CdSe structures are constructed. The microstructures and the photoelectrochemical properties of multilayer TiO2/CdSe structures are investigated. The results show that the CdSe thin films are grown preferentially along the (111) direction. The thickness and UV-Vis absorbance intensity of multilayer films increase with the increase of layer number of TiO2/CdSe structure. The results obtained from photoelectrochemistry measurement indicate that the optimal photoelectrochemical current response and open-circuit voltage are obtained in a biolayer TiO2/CdSe system, which therefore demonstrates the favorable photoelectrochemical properties.
Analysis of characteristics of a sharp turn from drought to flood in the middle and lower reaches of the Yangtze River in spring and summer in 2011
Authors: Shen Bai-Zhu  , Zhang Shi-Xuan  , Yang Han-Wei  , Wang Kuo  , Feng Guo-Lin  ,   Department of Atmospheric Sciences, Lanzhou University, Lanzhou 730000, China;,   Jilin Meteorological Science Institute, Changchun 130062, China;,   Laboratory for Climate Studies of China Meteorological Administration, National Climate Center, Beijing 100081, China
Published: December 2020

We use global reanalysis data probided by NCEP/NCAR, precipitation data at 740 observational stations of China provided by the National Climate Center of the China Meteorological Administration, and grid data of precipitation in 2011 provided by National Meteorological Information Center to analyze the phenomenon of a sharp turn from drought to flood in the middle and lower reacher of Yangtze River in early June 2011, and the characteristics of its circulation background and briefly conclude as follows: 1) the precipitation in the middle and lower reaches of the Yangtze River was less and its change rate was smaller than that of corresponding climatological normals from January to May in 2011, both surged suddenly in June, leading to the appearence of a sharp turn from drought to flood in June, and the kickpoint was at the 31st pentad (the 1st pentad in June); 2) around the sharp turn, both flood water vapor flux and the space-time evolution characteristics of the first and the second modes of EOF analysis represented the transform of water vapor transport from a weaker state to a stronger one; 3) before and after the turn, atmospheric circulation fields were significantly different. Before the sharp turn, winter monsoon in northern hemisphere was strong, and summer monsoon in southern hemisphere was weak, leading to the delay of monsoon tranform, stronger East Asian Trough, which went against warm-moist air blowing to the north. All of that eventually led to less rainfall in south China and occurance of this sharp turn. In early June, the period of turining, the circulation was adjusted quickly, which presented that the western Pacific subtropical high extended to west and jump to north abruptly, East Asian Trough kept strong and was maintained in the west, and blocking high located in the Okhotsk Sea weakened. Thus, cold and warm air converged in the middle and lower reaches of the Yangtze River and contributed to the occurance and continuation of precipitation. It is the main reason of the sharp turn from drought to flood in the middle and lower reaches of the Yangtze River.
Thresholds for kinetic and potential energies of Arq+ induced Au target atomic M-X rays emission
Authors: Zhang Xiao-An  , Li Yao-Zong  , Zhao Yong-Tao  , Liang Chang-Hui  , Cheng Rui  , Zhou Xian-Ming  , Wang Xing  , Lei Yu  , Sun Yuan-Bo  , Xu Ge  , Li Jin-Yu  , Xiao Guo-Qing  ,   Ion Beam and Optical Physical Joint Laboratory of Xianyang Normal University and Institute of Modern Physics, Chinese Academy of Sciences, Xianyang 712000, China;,   Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China
Published: December 2020

The X ray emissions from Arq+ (the kinetic energy 150 keV and 1.2 MeV) beams impinging on Au surface are measured. The results show that the about 2 keV minimum-potential energy of Ar11+ and Ar12+ (150 keV) is necessary for exciting Au atoms to emit M-X rays. The kinetic energy threshold for exciting target atomic X ray emission is estimated by the semiclassical approximation theory of binary collision.
Dynamics of vertical-cavity surface-emitting laser subject to optical injection and positive optoelectronic feedback
Authors: Cao Ti  , Lin Xiao-Dong  , Xia Guang-Qiong  , Chen Xing-Hua  , Wu Zheng-Mao  ,   School of Physical Science and Technology, Southwest University, Chongqing 400715, China
Published: December 2020

Based on the spin-flip model (SFM), we theoretically investigate the dynamics of a vertical-cavity surface-emitting laser (VCSEL) subject to optical injection and positive optoelectronic feedback. The results show that under the joint action of positive optoelectronic feedback and optical injection from a master VCSEL (M-VCSEL), two polarization modes of a slave VCSEL (S-VCSEL) will show many dynamic states such as period one, period two, multi-period and chaos, and the evolution routes of these states are different for two polarization modes. Mapping of dynamic region as a function of feedback strength f and injection strength is varied with frequency detuning between M-VCSEL and S-VCSEL (=m-s, where m ands are the free-running frequencies of M-VCSEL and S-VCSEL, respectively). Compared with the case for zero or negative frequency detuning, the region of chaotic state is expanded significantly under positive . For a fixed , the influences of f and on the chaotic bandwidth of S-VCSEL are discussed. Through selecting proper f and , chaotic bandwidth of S-VCSEL can be improved obviously.
Hybrid simulation of stimulated Brillouin scattering in laser fusions
Authors: Liu Zhan-Jun  , Hao Liang  , Xiang Jiang  , Zheng Chun-Yang  ,   Institute of Applied Physics and Computational Mathematics, Beijing 100094, China;,   Center for Applied Physics and Technology, Peking University, Beijing 100871, China
Published: December 2020

In laser plasmas interactions, the simulation of stimulated Brillouin scattering takes a long time. In order to decrease the simulation time, a hybrid Vlasov code is developed, in which the electrons are treated as Boltzmann fluid. The two-ion beam instability is simulated, and the simulation results are compared with the theoretical results. Stimulated Brillouin scattering is also simulated, the results show the code correctness.
Experimental research on viscoelastic behavior for pump-oil saturated sandstones
Authors: Xi Dao-Ying  , Xu Song-Lin  , Du Yun  ,   Mengcheng National Geophysical Observatory, School of Earth and Space Science, University of Science and Technology of China, Hefei, 230026, China;,   Key Laboratory for Mechanical Behavior and Design of Materials, Chiese Academy of Sciences, University of Science and Technology of China, Hefei 230027, China
Published: December 2020

Experiments are performed by Metravib dynamic mechanical analyzer (DMA+450) using the stress-strain method. The static load is fixed at 100 N, and the dynamic load amplitude of the sine wave is 60 N, so that the total loading force is controlled under yield stress. Temperature is controlled between -50 ℃ and 175 ℃, and the heating rate is 1 ℃ per min. The frequency ranges from 1 Hz to 1000 Hz. Pump-oil saturated arkoses and Pengshan sandstones are tested under uniaxial cyclic loading. The variations of attenuation, phase angle, Young's modulus, and velocity with temperature or frequency are obtained. The attenuation peak and the phase angle peak shift toward higher temperatures with frequency increasing, which can be considered as thermal relaxation regularity. The activation energy and the transition frequency corresponding to the thermal relaxation peak are determined by experimental results and explained by the sandstone characteristics. A new phase transition attenuation peak, which is corresponding to mineral ion exchange in rock, is observed in the present experiments. Some dynamic characteristics of rock minerals under thermal and vibration loading are used to explain the peak. The Young's modulus and the velocity increase with frequency increasing and decrease with temperature increasing. There is obvious frequency dispersion, and the dispersion weakens when temperature increases. This investigation is helpful for studying theoretical model and interprating seismic data.
A Study of the hydrodynamic behavior of cylindrical structure with double porous outer shelters
Authors: Liu Jun  , Lin Gao  , Li Jian-Bo  ,   State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology, Dalian 116024, China;
Published: December 2020

Porous structure can effectively reduce the loads caused by the water wave, which results in lowering the cost of engineering project. The double porous shelter performs even better. Therefore, it receives much attention from researches. However, most of the previous studies dealing with the analysis of the interaction between water wave are porous structure were based on two-dimensional plane wave assumption. This can hardly reflect the real phenomena of complex wave action. In this paper, a semi-analytical solution to the hydrodynamic interaction between the three-dimensional short-crested wave and the cylindrical structure with double porous shelters is performed by employing the scaled boundary finite element method (SBFEM). The SBFEM possesses the advantages of finite element method (FEM) and boundary element method (BEM): the spatial dimension of the problem is reduced by one, no fundamental solution is needed and no singularity occurs. Meanwhile, this method can meet the infinity of the boundary condition automatically. In the SBFEM, the total computational domain is divided into three sub-domains, two ring-shaped finite sub-domains and one outer infinite sub-domain. A variational principle approach is proposed to establish the SBFE governing equations, which describe the variation of the velocity potential of wave motion in the radial direction. Bessel functions and Hankel functions are chosen as the basis functions for the solution of bounded and unbounded sub-domain problems, respectively. Numerical examples show that the proposed approach achieves very high accuracy and converges rapidly with quite few discretized nodes at the outer boundary. In comparison with the cylindrical structure with single porous shelter, the former performs better for the reduction of the water wave force. In addition, The influences of the wave parameters and the configuration of the structure on the system hydrodynamics, including the wave force, wave and diffracted wave contour are extensively examined. This research provides a valuable insight into the hydrodynamic analysis of cylindrical structure with double porous shelters and their structural design.
A study of two-dimensional hexagonal phase array optical beam splitter modulated by external electric field
Authors: Li Jian-Guang  , Chen Yun-Lin  , Zhang Jin-Hong  ,   School of Science, Beijing Jiaotong University, Beijing 100044, China
Published: December 2020

In this paper, we establish a theoretical model of reciprocal-lattice vector of the two-dimensional hexagonal phase array optical beam splitter modulated by an external electric field, perform the analysis of the tunable phase-difference array optical beam splitter according to the numerical simulation, and then obtain the images of intensity distribution with different values of fractional Talbot distance and external electric field. The two-dimensional hexagonal phase array optical beam splitter is designed and fabricated by lithium niobate. An experimental study of beam splitting is also given. When the applied voltage is 0.5 kV (with electric field of 1 kV/mm), we observe the phenomenon of the beam splitting in Talbot diffraction. As the external field increases, the images of beam splitting in diffraction become clearer, the experimental results are in agreement with theoretical results.
Preparation and near-infrared luminescence properties of Bi-doped BaO-B2O3glasses
Authors: Liu Jun-Fang  , Su Liang-Bi  , Tang Hui-Li  , Xu Jun  ,   College of Materials Science and Engineering, Tongji University, Shanghai 200092, China;,   Key Laboratory of Advanced Civil Engineering Materials (Tongji University), Ministry of Education, Shanghai 200092, China;,   Key Laboratory of Transparent and Opto-Functional Inorganic Materials, Shanghai Institute if Ceramics, Chinese Academy of Sciences, Shanghai 201800, China
Published: December 2020

Bi-doped BaO-B2O3 glasses are prepared by the melting method. Visible and infrared luminescence spectra, fluorescence decay curve and Raman scattering spectra are measured. NIR emissions, not only one broadband emission peak but also several emission peaks, appear in Bi-doped BaO-B2O3 glass under 808 nm LD pumping. The effect of the network structure of BaO-B2O3 glass on the NIR emission is discussed, and the mechanism for the emission is investigated preliminarily.
Structure and spectral properties of Yb3+:Gd2SiO5 crystal
Authors: Ning Kai-Jie  , Zhang Qing-Li  , Zhou Peng-Yu  , Yang Hua-Jun  , Xu Lan  , Sun Dun-Lu  , Yin Shao-Tang  ,   The Key Laboratory of Photonic Devices and Materials, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China;,   Graduate University of Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

15at.%Yb3+:Gd2SiO5 crystal with a size of30 mm75 mm is grown by the Czochralski method, and its lattice parameters, atom coordinates and temperature factors are determined by the full-profile Rietveld refinement method. Its spectral parameters of oscillator strength, line strength, transition probability, energy lifetime and integral emission cross-section for Yb3+2F7/22F5/2 transition are calculated using the absorption spectraum. And the laser performance evaluation shows that this crystal is a potential laser crystal with relatively high threshold, and could be used as a medium of tunable or ultra-fast laser pumped by high-power laser diode.
Structures and melting behaviors of ultrathin platinum nanowires
Authors: Xia Dong  , Wang Xin-Qiang  ,   Department of Physics, Chongqing University, Chongqing 401331, China
Published: December 2020

The amorphous-like structures and melting behaviors of ultrathin platinum nanowires are studied by EAM potential by using empirical molecular-dynamic simulation and the dependence of nanowire melting temperature pm soze os pntaomed. When the Lindeman criterion is 0.03, we find that the melting temperature for Pt nanowires is well consistent with the result obtained from the potential energy. Through comparing the Lindemann indexes on each shell, the thermal stability is studied. The results indicate that melting of the cylindrical helical structures starts from the interior atoms and that of the bulklike rectangular structure starts from the surface. We also observe the positions of the atoms at different temperatures to obtain the atomic diffusion and mobility.
The effects of local density of states on surface plasmon polaritons
Authors: Han Qing-Yao  , Tang Jun-Chao  , Zhang Chao  , Wang Chuan  , Ma Hai-Qiang  , Yu Li  , Jiao Rong-Zhen  ,   Science School, Beijing University of Posts and Telecommunication, Beijing 100876, China
Published: December 2020

Surface plasmon polariton (SPP) is a kind of electromagnetic oscillation coupling due to the undulation of charge intensity, which is excited at the interface between metal and dielectric. With the help of near-field enhancement, surface plasmon polariton plays an important role in nano-photonics. When the effect of SPP is used to fabricate the single photon resource, not only the volume can be miniaturized, but also the single photon radiation and collection efficiency can be effectively improved. According to the relationship between the factor of Purcell effect and the density of states, we calculate the local density of electromagnetic states(LDOS) and Purcell factor. By analyzing the local densities of electromagnetic states of different metallic materials, we find that silver is the most suitable metal. For a certain metal, the detection distance and the dielectric material also have influences on local density of electromagnetic states and Purcell factor, and they provide important parameters for the designing of single photon resource based on surface plasmon resonances.
Synthesis and characteristic research of nanoparticles KY3F10: Yb, RE (RE=Er, Ho, Tm) by thermal decomposition
Authors: Peng Yong  , Xing Ming-Ming  , Luo Xi-Xian  , Wang Li-Qiang  ,   Institute of Optoelectronic Technology, Department of Physics, Dalian Maritime University, Dalian 116026, China
Published: December 2020

Organic dyes and quantum dots possess the defects: wide emission spectrum and the poor photothermal stability and cytotoxicity, which restricts their applications in biological studies. Lanthanide-doped upconversion fluorescent materials in which there exists neither autofluorescence nor light bleaching phenomenon, has high sensitivity and good long-term stability, which are conducive to in vivo detection. KY3F10: Yb, RE(RE=Er, Ho, Tm) nanocrystals are synthesized by the thermal decomposition method and oleic acid as surface coating agent. The effects of the oleic acid content on morphology and particle size are studied. Optimal ratio of oleic acid to octadecene is 3:1 for the preparation of spherical monodisperse nanocrystals. Strong yellow green, green and blue emissions from the prepared samples are observed at 980 nm laser excitation. These results show that KY3F10: Yb, RE (RE=Er, Ho, Tm) nanoparticles as biological probes have excellent features in multiple fluorescent markers.
Stable behavior of solution for the reaction-diffusion system of atmospheric nonlinear dynamics and thermodynamics
Authors: Chen Li-Hua  , Lin Wan-Tao  , Lin Yi-Hua  , Mo Jia-Qi  ,   Department of Mathematics and Computer Science, Fuqing Branch of Fujian Normal University, Fuqing 350300, China;,   State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamic, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China;,   Department of Mathematics, Anhuii Normal University, Wuhu 241003, China
Published: December 2020

A class of nonlinear system is studied. Firstly, the reaction-diffusion system with speed, temperature and humidity for a atmospheric nonlinear force dissipative system is discussed using the atmospheric nonlinear theory of thermodynamics and dynamics. Secondly, the small disturbed solution of atmospheric nonlinear reaction-diffusion system in the neighborhood of homogeneous steady state solution is obtained from the Lyapunov stability theory. Finally, from the variations of the control parameters for transgenic processes, the states of ordered-unordered-ordered processes of atmospheric nonlinear reaction-diffusion system are found. Thus the corresponding local atmospheric nonlinear force dissipative system can be predicated and calculated.
Laser without inversion in a Δ -configuration three-level system with cyclic transition
Authors: Gao Qiang  , Song Tong-Qiang  ,   Department of Physics, Ningbo University, Ningbo 315211, China
Published: December 2020

In the case of incoherent pumping, laser without population inversion in a resonant three-level Δ -configuration system is investigated. By taking the strong coupling field limit, we obtain the approximate steady-state analytical solution of populations and imaginary part of coherences within the dressed-state regime, and discuss the condition of the generating of laser without inversion and the dependences of population distribution and system gain on Rabi frequency of the probe and coherence fields. The results show that the resonant three-level Δ-configuration system is always in the state of no population inversion, and laser without inversion occurs if one of the two fields is strong. When one of the two fields is much stronger than the other one, the gain without inversion is independent of the two Rabi frequencies.
Structural, magnetic, transport, and half-metallic properties of Fe2Co1-xCrxSi Heusler alloys
Authors: Du Yin  , Wang Wen-Hong  , Zhang Xiao-Ming  , Liu En-Ke  , Wu Guang-Heng  ,   State Key Laboratory of Magnetism, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
Published: December 2020

The structural, the magnetic, the transport and the half-metallic properties of quaternary Heusler alloy Fe2Co1-xCrxSi are investigated. The studies of X-ray diffraction and temperature dependence of magnetization reveal that Fe2Co1-xCrxSi alloy always maintains a high degree of order, while the Curie temperature decreases gradually with the increase of Cr concentration x. Importantly, the lattice constant and the saturation magnetic moment of Fe2Co1-xCrxSi alloy follow the Vegard law and half-metallic Slater-Pauling rule, respectively. Based on the band structure calculation, Fe2Co1-xCrxSi alloy keeps a 100% spin polarization and Fermi level moves from the top of valence band to the bottom of conduction band, depending on Cr concentration x. Our results indicate that quaternary Fe2Co1-xCrxSi Heusler alloy is a promising robust half-metallic candidate for spintronics applications.
A four-level quantum refrigeration cycle
Authors: He Xian  , He Ji-Zhou  , Xiao Yu-Ling  ,   Department of Physics, Nanchang University, Nanchang 330031, China
Published: December 2020

A four-level entangled quantum refrigeration cycle working with a two-qubit entangled system is proposed in this paper. Based on the first law of quantum thermodynamics and the concept of thermal entanglement, the relation between the quantum entanglement and the several thermodynamic quantities such as the heat transfer, the input work and the coefficient of performance is analyzed. It is found that the isoline of the coefficient of performance is the loop line and it no longer monotonically changes with the ratio of entanglement; in a small exchange constant J the operation region of the refrigerator is c1>c2 and in a larger exchange constant J the operation region of the refrigerator may be c1>c2 or c1c2; the maximal coefficient of performance increases as the exchange constant increases.
Systematic analysis of the fusion barrier heights and positions for projectile using the double folding model
Authors: Qu Wei-Wei  , Zhang Gao-Long  , Le Xiao-Yun  ,   State Key Laboratory of Software Development Environment, Beijing 100191, China;,   School of Physics and Nuclear Energy Engineering, Beihang University, Beijing 100191, China
Published: December 2020

The relations of fusion barrier height and position to charge number and root-mean-square radus of the interacting nucleus for projectile fusing with the different target nuclei are systematically analyzed in this paper. The nuclear potential is calculated by using the double folding model with the density-dependence nucleon-nucleon interaction(CDM3Y6). The pocket formulas are obtained for the fusion barrier height and position for projectile fusing with the different nuclei with mass in a range from 16 to 238. The parameterized formulas can reproduce the exact barrier heights and positions only for projectile within the accuracy of 1%. Moreover, the results are perfectly agreeable with the experimental data, the empirical data and the results of Royer, KNS, AW and the proximity potential.
Coherence properties of supercontinuum quantified by complex degree of self-coherence
Authors: Jin Ai-Jun  , Wang Ze-Feng  , Hou Jing  , Guo Liang  ,  Jiang Zong-Fu  , Xiao Rui  ,   College of Optoelectronic Science and Engineering, National University of Defense Technology, Changsha 410073, China;,   Beijing Institute of Radiation Medicine, Beijing 100850, China
Published: December 2020

The complex degree of self-coherence is introduced to quantify the coherence of supercontinuum generated by the same long pulse, and experiments are performed. The coherence properties of supercontinuum generated in the photonic crystal fiber pumped by 700 ps pulse are measured using the Mach-Zehnder interferometer. The experimental results show that the coherence lengths of different wavelength parts of the supercontinuum are all longer than 40 m, and can reach 225 m in the long wavelength region. The coherence degrees of different parts of supercontinuum are not the same; however, the mean coherence degree over the supercontinuum is 0.461 which manifests good coherence property of the whole spectrum of supercontinuum. Consequently, requirements of many applications such as optical measurement and optical sensing can be satisfied.
Reflection type single-order diffraction grating
Authors: Weng Yong-Chao  , Kuang Long-Yu  , Gao Nan  , Cao Lei-Feng  , Zhu Xiao-Li  , Wang Xiao-Hua  , Xie Chang-Qing  ,   State Key Laboratory of High-Power Semiconductor Lasers, Changchun University of Science and Technology, Changchun 130022, China;,   Key Laboratory of Nano-Fabrication and Novel Devices Integrated Technology, Institute of Microelectronics, Chinese Academy of Sciences, Beijing 100029, China;,   National Key Laboratory of High-temperature and High-density Plasma Physics, Research Center of Laser Fusion China Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

The development trend of single-order diffraction grating is introduced. The feasibility of single-order diffraction grating is theoretically demonstrated, and a novel diffractive optical element named quasi-sinusoidal reflection type single-order diffraction grating(QSRG) is proposed. It can suppress higher order diffraction, and improve the signal-noise-ratio (SNR) and accuracy. The experimental results verify this new type of dispersion component, where the higher order diffraction components are efficiently suppressed, which accords well with theoretical prediction. These results are expected to be widely used in the reflection spectrum measurement system.
Simulation and experimental study of a metamaterial panel for mechanical wave absorption
Authors: Sun Hong-Wei  , Lin Guo-Chang  , Du Xing-Wen  , P.F. Pai  ,   Key Laboratory of Science and Technology for National Defence, Harbin Institute of Technology, Harbin 150001, China;,   Department of Mechanical and Aerospace Engineering, University of Missouri, Columbia, MO 65211, USA
Published: December 2020

Based on the mechanical wave selective absorption principle of mass-spring microstructures by the optical vibration mode, a two-dimensional acoustic metamaterial panel consisting of lumped mass and elastic membrane is presented. The vibration characteristic simulation of the metamaterial equivalent panel representative cell is performed using the finite element method and the results indicate that the presented 2D metamaterial panel behaves just like regular mass-spring microstructures. Under the guidance of the simulation results, a square metamaterial panel is fabricated and its vibration characteristics are examined using a Polytec scanning laser vibrometer. The test results indicate that the metamaterial panel can efficiently absorb mechanical waves of about 157.5 Hz.
3D simulation of the electron energy distribution in negative hydrogen ion source
Authors: Yang Chao  , Liu Da-Gang  , Liu La-Qun  , Xia Meng-Zhong  , Wang Hui-Hui  , Wang Xiao-Ming  ,   University of electronic Science and Technology of China, Chengdu 610054, China
Published: December 2020

In this paper, we calculate permanent magnet theoretically for a multicusp ion source Coulomb collision between electrons is treated with the "binary collision" model and collisions between the electrons and hydrogen species are treated with the "null-collision" method. A 3D PIC-MCC simulation algorithm is developed, and based on this algorithm the electron deposition process in multicusp ion source is simulated, and the multicusp magnetic field effects on the electron energy distribution and spatial distribution are analyzed. The results show that the spatial non-uniformity of electron distribution comes from high energy electron B× ▽B drift in the filter field.
The surface effect on the p-type conductivity of Li-doped ZnO film
Authors: Si Hang  , He Hai-Yan  , Pan Bi-Cai  ,   Department of Physics, University of Science and Technology of China, Hefei 230026, China;,   Hefei National Laboratory for Physical Sciences at Microscale, Hefei 230026, China
Published: December 2020

By using the first-principles method, we study the relative stabilities and the thermal ionization energies of the doped Li (LiZn) in the different atomic layers for both the non-polar and polar surfaces. Our calculations indicate that the LiZn in the surface region is more stable than in the ZnO bulk, and the thermal ionization energy of the LiZn in the surface region is considerably bigger than in the ZnO bulk. So, the surface of ZnO film degrades the p-type conductivity of the Li-doped film significantly, which is important for the p-type doping in the low-dimensional ZnO system. Furthermore, we find that the observed difference in thermal ionization energy of LiZn between a surface and bulk actually stems from the different distributions of the electrostatic potentials between a surface and bulk.R66
The influences of air heat storage, plant photosynthesis and soil water movement on surface energy balance over the loess plateau
Authors: Li Hong-Yu  , Zhang Qiang  , Wang Chun-Ling  , Yang Fu-Lin  , Zhao Jian-Hua  ,   Institute of Arid Meteorology, CMA; Key laboratory of Arid Climatic Change and Reducing Disaster of Gansu Province; Key Open Laboratory of Arid Climatic Change and Disaster Reduction of CMA, Lanzhou 730020, China;,   College of Applied Meteorology, Nanjing University of Information Science & Technology, Nanjing 210044, China
Published: December 2020

The surface energy imbalance problem has become a challenge in the study of surface land process since it was found in the late 1980s. By using data provided by the program the Loess Plateau Land-surface Process Experiment (LOPEX) and introducing the vertical sensible heat flux into the surface energy balance equation, in the paper, we estimate the heat storage associated with change of air temperature and humidity as well as the energy stored in plants due to the photosynthesis, determine the water vertical flux in the shadow soil layer both by water conservation principle and two-level soil temperature, and investigate the influences of air and plant photosynthesis energy storages and heat transferred by the soil water movement on the surface energy budget. It is found that the diurnal variation peaks of averaged energy storages of air and plant photosynthesis reach 1.5 and 2.0 Wm-2 respectively. Additionally, the diurnal variation peak of mean heat transferred by vertical water movement is close to 8.0 Wm-2. The closure of energy balance is improved from 88.1% to 89.6% by adding the three additional energy terms to the energy balance equation. As a whole, the energy storage related to air and the plant photosynthesis, and the heat transferred by the soil water movement both promote the surface energy balance to some extent. Furthermore, the semi-arid climate and the vegetation condition of Loess Plateau essentially lead to significant differences of energy storage be tween this area and other climatic districts.
Radiation power of electric diople in magnetic anisotropic medium
Authors: Hong Qing-Quan  , Zhong Wei-Bo  , Yu Yan-Zhong  , Cai Zhi-Shan  , Chen Mu-Sheng  , Lin Shun-Da  ,   School of Physics and Information Engineering, Quanzhou Normal University, Quanzhou 362000, China
Published: December 2020

Under the framework of classical electrodynamics, the electromagnetic radiation in magnetic anisotropic medium is studied in the present paper. The radiation power expression for electric dipole in magnetic anisotropic medium is deduced. The obtained expression in isotropic medium accords with that in the literature, and its validity is therefore proved. The radiation effect of electric dipole in magnetic anisotropic medium can be estimated by the obtained results. It has practical significance for further research electromagnetic property in magnetic anisotropic medium and effective development and utilization of magnetic anisotropic medium.
Research on the opacity of Fe M-shell unresolved transition array
Authors: Dong Fu-Tong  , Wang Fei-Lu  , Zhong Jia-Yong  , Zhao Gang  ,   National Astronomical Observatories, Chinese Academy of Science, Beijing 100012, China
Published: December 2020

M-shell unresolved transition array of iron is an important diagnostic tool of the X-ray spectrum of active galactic nuclei. This array is measured in the laboratory, and compared with several theoretical models. In the present paper, we introduce a detailed line counting model. With this model, we simulate the experimental spectra, and the comparison shows a good agreement. We also calculate the absorption spectra in a temperature range of 1050 eV.