bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis on the stability of the electronic transport properties of single-walled carbon nanotubes
Authors: Mei Long-Wei  , Zhang Zhen-Hua  , Ding Kai-He  ,   长沙理工大学物理与电子科学学院,长沙  410076
Published: December 2020

Based on energy dispersion relation of the deformed single-walled carbon nanotubes （SWCNTs）, various curves of the electronic velocity and effective mass of the lowest conduction band versus deformation parameters for SWCNTs are computed. It is found that only when a deformation occurs in the special direction（s） and is limited to a region of low deformation （the deformation parameter ε≤002）, the variations of the electronic average velocity vmean and average effective mass m*mean of different types of SWCNTs are very small （the relative variation≤2%）, which suggests that in these cases the electronic transport properties for SWCNTs under a low bias are basically stable. Whereas in other cases the electronic average velocity, or electronic average effective mass, or both of them vary significantly, even change in a dramatic way. This means that the electronic transport properties for SWCNTs under a low bias are unstable, even extremely unstable.
Research of surface enhanced Raman scattering caused by surface plasmon of Ag nano-structures
Authors: Huang Qian  , Wang Jing  , Cao Li-Ran  , Sun Jian  , Zhang Xiao-Dan  , Geng Wei-Dong  , Xiong Shao-Zhen  , Zhao Ying  ,   (1)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; (2)南开大学化学学院化学系，天津  300071
Published: December 2020

Silver nano-structures were synthesized through thermal evaporation. Scanning electron microscopy （SEM） observations showed that the silver nano-structures had several types of morphology. The optical properties of silver nano-structures were obtained by ultraviolet-visible spectrometry, which shows the resonance wavelength of surface plasmon. In this work, we demonstrate the surface enhanced Raman scattering （SERS） signals which allow us to track down the surface plasmon local field spectra of Ag nano-structures. To prove it, we also used rhodamine 6G deposited on samples. As a result, we show that the transmittance spectra and SERS enhancement gives a complete description of optical and electric field caused by surface plasmon resonance of Ag nano-structures. The difference of Raman enhancement also indicates that different structures give different surface plasmon intensity when combined with the result of SEM.
Effect of laser irradiation on La0.67Ba0.33MnO3 thin films
Authors: Chang Lei  , Jiang Yi-Jian  ,   (1)北京工业大学激光工程研究所，北京  100124; (2)北京工业大学激光工程研究所，北京  100124；北京工业大学材料科学与工程学院，北京  100124
Published: December 2020

La067Ba033MnO3 thin films were grown on LaAlO3 substrate using pulsed laser deposition. The microstructure, magnetic and electrical properties of as-grown, annealed and CO2-laser-irradiated （CLI） LBMO films were studied. It is found that, after laser irradiation, the enhancement of the crystallinity of the film is accompanied by the emergence of the plain-like surface morphology with smaller roughness. The structure and magneto-transport properties of LBMO films are markedly improved in several dozens of seconds via CO2 laser irradiation. Compared with the annealing treatment, laser irradiation is a fast and effective way to tailor CMR manganites for industrial applications.
Magnetoresistance induced by the stress fieldin ferromagnetic multilayer
Authors: Xu Xiao-Yong  , Qian Li-Jie  , Hu Jing-Guo  ,   江苏扬州大学物理科学与技术学院，扬州  225002
Published: December 2020

By investigating the spin configuration in ferromagnetic multilayer under stress field, the dependence of magnetoresistance （MR） upon the stress field in the ferromagnetic multilayer is discussed. The stress field can induce MR, and the MR strongly depends on both the value and the direction of the stress field. Generally, for the case of J>0, the stress field dependence of MR is closely related with the differences in magnetostriction and magnetocrystalline anisotropy between two ferromagnetic layers. When the stress field deviates from the magnetic easy axis lowards the magnetic hard axis, the MR first increases slowly, and then decreases rapidly. For a given direction of stress field, the MR first increases rapidly, later decreases slowly with stress field increasing. Moreover, when the direction of stress field approaches that of the hard axis, the dependence of MR upon both the value and the direction of the stress field becomes obvious. Especially, if the direction of the stress field is perpendicular to the easy axis, change of MR can double its value with the stress field increasing. When the stress field Hλ meets the condition 8πM/5≤Hλ≤18πM/5, MR increases monotonically, and the giant magnetoresistance （GMR） occurs. In the case of JJ>0.
Effect of microstructure on the magnetic properties of Pt-Co permanent magnetic alloy
Authors: Liu Tao  , Guo Zhao-Hui  , Li Xiu-Mei  , Li Wei  ,   钢铁研究总院功能材料研究所，北京  100081
Published: December 2020

The relationship between the magnetic properties and the microstructure of Pt-Co permanent magnetic alloys was studied. X-ray diffraction （XRD） results indicated that the as-cast Pt-Co alloy has a texture microstructure. According to the scan electron spectrum （SEM） results, the as-cast alloy has a columnar structure and the columnar crystal grows along the cooling direction. After plastic deformation and recrystallization, the texture was disappeared and the grains became smaller and more uniform. Compared with the columnar structure of Pt-Co alloys, the magnetic properties of the recrystallized alloys were improved obviously. So the grain size and direction may be the main factors which can affect the coerivity of Pt-Co alloys.
Effect of N-doping on the microstructure and properties of amorphous SiC:H diffusion barrier films
Authors: Liu Bo  , Tang Wen-Jin  , Song Zhong-Xiao  , Chen Ya-Shao  , Xu Ke-Wei  ,   (1)陕西师范大学大分子科学陕西省重点实验室，西安  710062; (2)西安交通大学金属材料及强度国家重点实验室，西安  710049
Published: December 2020

Hydrogenated amorphous a-SiC:H and a-SiCN:H with different nitrogen-concentration dielectric barrier films are prepared using the plasma-enhanced chemical vapor deposition technique （RF-PECVD）. The chemical and structural nature, mechanical property, dielectric constant and copper diffusion property of these films are characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy measurement, nano-indentation, Agilent 4294A precision impedance analyzer, Auger electron spectroscopy and field emission transmission electron microscopy. The results indicated that the dielectric constand of the film can be adjusted btween the values of 38 and 52 by controling the NH3/3MS ratio. With the increasing of NH3/3MS ratio, the concentration of Si-N and C-N bond structure is gradually increase and micro-structure of the film becomes more dense, which is the mechanism of the improvement in the mechanical property, thermal stability and copper diffusion property of the a-SiC:H based film produced by N-doping.
Effect of temperature on optical bistability of coated granular composites
Authors: Wu Ya-Min  , Chen Guo-Qing  ,   江南大学理学院，无锡  214122
Published: December 2020

We study the intrinsic optical bistability（OB） of nondilute suspensions of coated spherical particles with a metallic core and a nonlinear dielectric shell. In this kind of system， as the spatial local field is not uniform, it cannot be obtained exactly. In this connection，we establish the self-consistent mean field approximation， and obtain the spatial average of the local field squared in the core as a function of the external applied field. Numerical results show that the optical bistability（OB） is dependent on the temperature T， the structural parameter k， and the volume fraction f. For given k and f， the width of optical bistability decreases with increasing temperature. At further increasing of T， OB is found to vanish. On the other hand， for given T and f， the bistable region gradually increases as the structural parameter k increases， accompanied with the increase in both the upper and lower threshold fields. More exactly， the increase of the bistable region mainly results from the rapid increase in the upper threshold field.
Studies on the dynamic process of up-conversion green emission from Er3+ under square wave excitation
Authors: Dong Li-Qiang  , Huang Shi-Hua  , Jia Xiao-Xia  , Chen Bao-Jiu  ,   (1)北京航空航天大学电子信息工程学院，北京  100083; (2)北京交通大学光电子技术研究所，发光与光信息技术教育部重点实验室，北京  100044; (3)大连海事大学物理系，大连  116026
Published: December 2020

The rise and decay curves of Er3+2H11/2 and 4S3/2 upconversion emission in oxyfluoride tellurite glass were measured under the excitation of 808 nm and 980 nm light from laser diodes driven by square wave. Different rise times under 808 nm and 980 nm excitation reveals different excitation paths. Relationship between build-up process of the upconversion emission and lifetime of the intermediate state was analyzed with the rate equations. Excitation processes of the green upconversion emission under 808 nm and 980 nm excitation were confirmed. Square wave excited upconversion emission may also be used for measuring lifetimes of infrared energy levels with a conventional photomultiplier tube.
Structure phase transition from α to ε in Fe under non-hydrostatic pressure: an ab initio study
Authors: Lu Zhi-Peng  , Zhu Wen-Jun  , Liu Shao-Jun  , Lu Tie-Cheng  , Chen Xiang-Rong  ,   (1)北京师范大学物理系，北京  100875; (2)四川大学物理科学与技术学院，成都  610064; (3)四川大学物理科学与技术学院，成都  610064；中国工程物理研究院流体物理研究所冲击波物理与爆轰物理重点实验室，绵阳  621900
Published: December 2020

We performed first-principles calculations for the pressure-induced martensitic phase transition from the ground state ferromagnetic bcc phase to a nonmagnetic hcp phase in Fe under hydrostatic and non-hydrostatic pressure based on density-functional theory, employing the pseudopotentional and plane-wave method. The calculated results show that the magnetic moment of bcc iron under non-hydrostatic conditions decreases faster than that under hydrostatic conditions as the stress increases from 0 GPa to 18 GPa. Theoretical calculations prove that non-hydrostatic conditions can significantly reduce the bcc phase to hcp phase transition pressure. The critical stress for bcc-to-hcp transformation decreases linearly as the non-hydrostatic effect increases. The physical origins of the influence of non-hydrostatic pressure on the transition pressure are discussed.
Friction force between wall and granular matter for a silo with unsaturated stress
Authors: Peng Zheng  , Li Xiang-Qun  , Jiang Li  , Fu Li-Ping  , Jiang Yi-Min  ,   (1)中南大学物理科学与技术学院，长沙  410083; (2)中南大学物理科学与技术学院，长沙  410083；中南大学粉末冶金国家重点实验室，长沙  410083
Published: December 2020

For a silo with unfixed wall, the pressure on its bottom will increase linearly with the height of granular material filled in it. Because no Janssen stress saturation occurs, its mechanic states differ from that of usual silo. By vertically pulling and pushing the wall of the silo, we measured the maximum static friction force of the wall, as functions of the load applied on the silo top and the mass filled in the silo. It is observed that the force increases with the mass, linearly for the pulling case, while exponentially for the pushing case, of which value for the latter may be one order of magnitude larger than that for the former. The force also increases with the load, linearly for both cases. The measurements can be well fitted with the theoretical results of continuous mechanics, assuming that ratio between horizontal and vertical stresses keeps the same everywhere inside the silo. The results support that the assumption made by Janssen for usual silo also suitable for the silo which has no stress saturation.
Research on the validility of cluster delineation based on spatial point processes
Authors: Yang Ping  , Hou Wei  , Zhi Rong  ,   (1)兰州大学大气科学学院，兰州  730000；国家气候中心，中国气象局气候研究开放实验室，北京  100081; (2)兰州大学大气科学学院，兰州  730000；中国科学院大气物理研究所，东亚区域气候环境重点实验室，北京  100029
Published: December 2020

On the basis of the two-dimensional Poisson process theory and spatial point process theory, we introduced the algorithm of cluster extraction which is based on k-th order distance, aiming at determining the valid range of the algorithm. We found that the ratio of cluster and cluster's densities and the number of data both have effect on the method. But the effect of the former much bigger than that of the latter. Furthermore, we introduced the concept of weight to extend the range of the simulated data, and gave the data different weights for delineating clusters, so that the range of this algorithm can be extended.
Research on the correlation of drought/flood spatial fields by using joint entropy
Authors: Hou Wei  , Yang Ping  , Zheng Zhi-Hai  , Gong Zhi-Qiang  ,   (1)兰州大学大气科学学院，兰州  730000；国家气候中心，中国气象局气候研究开放实验室，北京  100081; (2)兰州大学大气科学学院，兰州  730000；中国科学院大气物理研究所，东亚区域气候环境重点实验室，北京  100029; (3)中国科学院大气物理研究所，东亚区域气候环境重点实验室，北京  100029；国家气候中心，中国气象局气候研究开放实验室，北京  100081
Published: December 2020

Using a method of calculating the entropy based on the relativity of spatial fields to give a correlative index having the statistic characteristic of discrete spatial fields, we discuss the inherent rule of drought/flood and their spatial distributions in China. The result gives the associations of drought/flood distributions from 1470 to 2000, and shows that the actual relativity of drought/flood distributed fields is relative and not stochastic, being different from the random distributed fields, by calculating their entropy and matrix latent values. The every year's entropy shows the degree of the year's association with other ones. The greater the entropy is, the bigger the degree is, and vice versa. The similitude of climate state has a steady and obvious quasi-periodicity before 1820, whose size is about 113 years. After 1820, the size adds up to 130 years and the intensity is weakened. Another steady quasi-periodicity is 68 years, which is obvious from 1595 to 1820, and its size is changed from 61 years to 81 years. In other periods, the 68-year periodicity is not found obviously.
Scale analysis of global temperature based on correlation matrix theory
Authors: Zhi Rong  , Gong Zhi-Qiang  , Zheng Zhi-Hai  , Zhou Lei  ,   (1)兰州大学大气科学学院，兰州  730000；国家气候中心，中国气象局气候研究开放实验室，北京  100081; (2)兰州大学大气科学学院，兰州  730000；中国科学院大气物理研究所东亚区域气候-环境重点实验室，北京  100029; (3)中国科学院大气物理研究所东亚区域气候-环境重点实验室，北京  100029
Published: December 2020

A temperature correlation matrix is constructed by NCEP/NCAR reanalysis temperature data of 1948—2005, and the 99% confidence test is used to filter out correlation ‘noise'. We smooth the temperature data with step=5 d,10 d,… and construct correlation matrixes, and find that 365—730 d maybe a turning of time scale of temperature. Global average correlation coefficient Cglobal increases along with step size, but the rate is slower and slower. The positive correlation center（1625°W—775°E，75°N—125°S）（Area Ⅰ） and the negative correlation center（1575°W—325°E，275°—475°N）（Area Ⅱ） are the two areas we concern with, there is strong negative correlation between them. With the help of a 10a slipping window, we find that those 10a Cglobal had an abrupt change between 1981—1987a, and so did Area Ⅰ and Ⅱ. The points of strongest negative correlation on the North Pacific Ocean have been changing from 1948 to 2005.
Envelope periodic and solitary solutions of Davey-Stewartson equation
Authors: Gao Bin  , Liu Shi-Da  , Liu Shi-Kuo  ,   (1)北京大学物理学院，北京  100871; (2)北京大学物理学院，北京  100871；玉溪师范学院物理系，玉溪  653100
Published: December 2020

The Jacobi elliptic function expansion method is applied to construct the envelope periodic and solitary solutions to the Davey-Stewartson equation.
The extended F-expansion method and new exact solutions of the generalized KdV equation
Authors: Liang Li-Wei  , Li Xing-Dong  , Li Yu-Xia  ,   酒泉卫星发射中心，酒泉  732750
Published: December 2020

In this paper, the F-expansion method is revised by adding a term with negative index with constant c，then the irregular wave solutions are avoided. By using this method， different new periodic wave solutions expressed by the generalized KdV equation are obtained.In the special cases，these periodic wave solutions degenerate to the corresponding Jacobi elliptic function solutions，solitary wave solutions or trigonometric function solutions.
The analytic solution of the radial Schr?dinger equation for the superposed potentials
Authors: Hu Xian-Quan  , Cui Li-Peng  , Luo Guang  , Ma Yan  ,   重庆师范大学物理学与信息技术学院,重庆  400047
Published: December 2020

The method of solving the radial Schrdinger equation is studied by under the tight coupling condition of several positivepower and inversepower potential functions. The precise analytic solutions and the conditions that determine the existence of analytic solution are searched when the potential of the radial Schrdinger equation is V（r）=α1r8＋α2r3+α3r2+β3r-1＋β2r-3＋β1r-4. According to the single valued, bounded and continuous stipulations of wave function in a quantum system, firstly, the asymptotic solution is solved when the radial coordinate r→∞ and r→0; secondly, the asymptotic solutions are combined with the series solutions in the neighborhood of irregular singularities; and then the power series coefficients are compared. A series of analytic solutions of the stationary state wave function and the corresponding energy level structure are deduced by tight coupling between the coefficients of potential functions for the radial Schrdinger equation. And the solutions are discussed and the conclusions are made.
Two-mode integral form projection operator and its application in quantum optics
Authors: Xu Shi-Min  , Li Hong-Qi  , Wang Ji-Suo  , Xu Xing-Lei  ,   (1)菏泽学院物理系,菏泽  274015; (2)聊城大学物理系,聊城  252059
Published: December 2020

A two-mode integral form projection unitary operator is introduced. Using the technique of integration within an ordered product （IWOP） of operators, the transformation property of the integral form projection operator is studied, and its normal ordered expression is derived. Then the Hamiltonian of two-mode quantum harmonic oscillator system with coordinate-momentum coupling is diagonalized by virtue of the integral form projection operator, there by the eigenenergy and eigenfunction of the system are exactly solved. Lastly, a special case is discussed.
Analysis of decoy state quantum-key-distribution system
Authors: Jiao Rong-Zhen  , Zhang Wen-Han  ,   北京邮电大学理学院，北京  100876
Published: December 2020

The security of quantum-key-distribution system is analyzed using the decoy state protocol with two weak decoy states and one signal state. The comparison is based on the key generation rate as a function of distance for two types of decoy states: the vacuum and a weak decoy state, asymptotically approaching the theoretical limit of the most general type of decoy protocol, one-decoy-state protocol. We studied the two-decoy-state protocol in connection with the intensity of signal state, and the gain of signal states, the overall quantum bit error rate, the gain of single-photon states and the error rate of single-photon states and arrived at the optimal condition which maximizes the key generation rate.
Generalized uncertainty principle and entropy of three-dimensional BTZ black hole
Authors: Zhao Ren  , Li Huai-Fan  , Zhang Li-Chun  ,   山西大同大学物理系，大同  037009
Published: December 2020

Applying the new equation of state density motivated by the generalized uncertainty relation in the quantum gravity field，we investigate the black hole entropy on the background of three-dimensionnal BTZ. When the λ with the Planck scale，and relative to the dimensions of spacetime introduced in generalized uncertainty relation has a fixed value，we obtain the Bekenstein-Hawking entropy of BTZ black hole and the correction term. Because we have used the new equation of state density，in our results the divergence term appearing in the brick-wall model is removed，at the same time with holding the small mass approximation. Thus the correction value of the Bekenstein-Hawking entropy of the black hole is derived from the quantum statistical view. It depends the understanding of the correction value of the black hole entropy.
Evaluation of eigenactions of area and volume operators in loop quantum gravity
Authors: Shao Dan  , Huzio Noda  , Shao Chang-Gui  , Shao Liang  ,   (1)Department of Mathematical Sciences，Ibaraki University，Mitio 310-8512，Japan; (2)湖北第二师范学院理论物理研究所，武汉  430205; (3)江汉大学光电信息研究所，武汉  430056; (4)武汉科技大学理学院应用物理系，武汉  430081
Published: December 2020

Using a method and its results which deals with the geometrical operators consistently，a complete area spectrum is obtained. At the same time，a different interpretation and result is given for the action of the Euclidean term of Thiemanns Hamiltonian constraint. In the graphical scheme of the grasping action，using the simplification of any triple of grasping actions of the volume operator，the associated recoupling matrices are demonstrated. Employing the movements of grasps，a complete and exact general expression of recoupling matrix for any triple of grasp actings on any valent vertex is detailed.
Chaotic time series prediction based on fuzzy tree
Authors: Mao Jian-Qin  , Ding Hai-Shan  , Yao Jian  ,   (1)北京航空航天大学自动化科学与电气工程学院，北京  100191; (2)中国空空导弹研究院，洛阳  471009
Published: December 2020

In this paper, an adaptive-tree-structure-based fuzzy model is applied to predict chaotic time series. The fuzzy partition of input data set is adaptive to the pattern of data distribution to optimize the number of the subsets automatically by binary-tree model. A fuzzy area around every discriminant edge is set up by the membership functions corresponding to every subset of input data. A complex nonlinear function is obtained by piecewise linear approximation and smoothing the discontinuous at the discriminant edges of subsets to reduce the error of approximation. The fuzzy tree model is evaluated using prediction of the Mackey-Glass, Lorenz and Henon chaotic time series. In comparison with some existing methods, it is shown that the FT is also of less computation and high accuracy.
Dynamical analysis of DOG wavelet mapping with dilation and translation
Authors: Bao Bo-Cheng  , Hu Wen  , Kang Zhu-Sheng  , Liu Zhong  , Xu Jian-Ping  ,   (1)电子科技大学电子工程学院，成都  610054; (2)南京理工大学电子工程系，南京  210094; (3)南京理工大学电子工程系，南京  210094；江苏技术师范学院电气信息工程学院，常州  213001; (4)南京理工大学电子工程系，南京  210094；南京航空航天大学信息科学与技术学院，南京  210016; (5)西南交通大学电气工程学院，成都  610031
Published: December 2020

A 1-D smooth map constructed from DOG wavelet function is discussed in this paper. With analysis on the fixed points and the constructed iterative curves，its dynamical characteristics are thoroughly studied. It is found that the number of the fixed points will increase or decrease depending on the dilation and translation operation of the wavelet and thus the stable or unstable cross points and tangent point or zero points are produced. Numerical calculations are performed to obtain the dynamic behavior，bifurcation diagrams and Lyapunov spectra. Some nonlinear phenomena，such as period-doubling bifurcation，tangent bifurcation，boundary crisis bifurcation，periodic window，and imperfect Feigenbaum-tree，are revealed and investigated.
Differential cross sections for collisions between He isotope atoms and HBr molecules
Authors: Yu Chun-Ri  , Wang Rong-Kai  , Zhang Jie  , Yang Xiang-Dong  ,   (1)安庆师范学院物理与电气工程学院,安庆  246133; (2)贵州师范大学理学院,贵阳  550001; (3)四川大学原子与分子物理研究所,成都  610065
Published: December 2020

Differential cross sections (DCSs) for collisions in 3He-HBr, 4He-HBr, 6He-HBr and 7He-HBr are calculated by the close-coupling approach from the anisotropic intermolecular potential of the He-HBr system established by the author. The calculations are performed separately at the collision energies of 40 and 75 meV. The influence of the incident isotope He atoms on DCSs is discussed in detail. The results show that the angular distribution of the total DCSs at zero degree increases and the position of oscillation minimum of the same order gradually shifts towards small scattering angle along with the increase of the incident isotope He atom mass at identical collision energy. And crossing angle between the elastic and total inelastic DCSs gradually decreases and the total inelastic DCS gradually increases. The rainbow phenomenon becomes more evident the lower the collision energy and the larger mass of the incident He isotope atom.
Influence of electron gas on nuclear structure in compact objects
Authors: Dong Jian-Min  , Li Jun-Qing  , Su Xin-Ning  , Wang Yan-Zhao  , Zhang Hong-Fei  , Zuo Wei  ,   (1)兰州大学核科学与技术学院，兰州  730000; (2)兰州大学核科学与技术学院，兰州  730000；中国科学院近代物理研究所，兰州  730000; (3)中国科学院近代物理研究所，兰州  730000
Published: December 2020

The influence of electron gas on atomic nuclei 56Fe and 120Sr in compact matter has been studied by relativistic mean field theory in combination with Wigner-Seitz approximation.Bardeen-Cooper-Schrieffer approximation is used to deal with pairing correlations.The results show that single-particle energy levels, nucleon density distributions and root-mean-square radii are changed due to electron gas. The influence on protons is greater than that on neutrons.
Theoretical investigation on level structure of 1s inner-shell excited state and the related decay property of C Ⅱ ion
Authors: Shi Ying-Long  , Dong Chen-Zhong  ,   (1)西北师范大学物理与电子工程学院,兰州  730070; (2)西北师范大学物理与电子工程学院,兰州  730070；兰州重离子加速器国家实验室原子核理论研究中心,兰州  730000
Published: December 2020

Based on the multi-configuration Dirac-Fock method, the level structures and decay processes of the inner-shell excited states （1s2s22p2 and 1s2s2p3） created by 1s-2p photoexcitation of C Ⅱ ion have been studied systematically, which the correlation and relaxation effects, relativistic radiative corrections have been considered in the calculations. Auger and radiative transition energy, decay rate and linewidth for each inner-shell excited states of C Ⅱ ion has been calculated. Correspondingly, lifetimes of those autoionization states can be obtained via the Heisenberg uncertainty principle. A comparison of the present calculations with the latest experimental and available theoretical results is also presented.
Elastic collisions between O and D atoms at low temperature and accurate analytic potential energy function and molecular constants of the OD（X2Π） radical
Authors: Shi De-Heng  , Liu Yu-Fang  , Sun Jin-Feng  , Zhang Jin-Ping  , Zhu Zun-Lüe  ,   (1)河南师范大学物理与信息工程学院，新乡  453007; (2)空军第一航空学院基础部，信阳  464000; (3)信阳师范学院物理电子工程学院，信阳  464000
Published: December 2020

Interaction potential of the OD（X2Π） radical is constructed by employing the CCSD（T） theory in combination with the correlationconsistent quintuple basis set, augccpV5Z, in the valence range. Using the potential, the spectroscopic parameters are accurately determined. The present D0, De, Re, ωe, ωeχe and Be values are of 44574, 46225 eV, 009702 nm, 2724923, 453534 and 100096 cm-1, respectively, which are in excellent agreement with the recent measurements wherever available. A total of 23 vibrational states have been found when J = 0 by solving the radial Schrdinger equation of nuclear motion. The complete vibrational levels, classical turning points, initial rotation and centrifugal distortion constants when J = 0 are reported for the first time, which are in good agreement with the available experimental results. The total and various partialwave cross sections are calculated for the elastic collisions of O and D atoms in their ground states at low and ultralow temperatures when the two atoms approach each other along the OD（X2Π） potential energy curve. The impact energy range covers a vange from 10×10-11 to 10 ×10-3a.u.. One shape resonance has been found in the total elastic cross sections. Contribution to the total elastic cross sections by each partial wave is investigated carefully. The results show that the shape of the total elastic cross sections is mainly dominated by the s partial wave. The shape resonances coming from the higher partial waves are covered up by the strong s partial wave cross sections.
Influence of distributed wall loss on stability of gyrotron traveling wave amplifier
Authors: Sun Hai-Yan  , Jiao Chong-Qing  , Luo Ji-Run  ,   (1)中国科学院电子学研究所,北京  100190; (2)中国科学院电子学研究所,北京  100190；中国科学院研究生院,北京  100049
Published: December 2020

Based on the dispersion equation of electromagnetic mode and the nolinear theory of gyrotron traveling wave amplifier (gyro-TWA), the influence of the thickness of the lossy layer on beam-wave interaction in the gyro-TWA is studied. The simulation results show that large attenuation for competing mode TE21 can be realized while that of operating mode is small by appropriately choosing the thickness and conductivity of the lossy layer. The bandwidth decreases with the increase of the thickness, but the output power of the middle of the bandwidth increases and becomes more smooth. This is useful for improving the stability of gyro-TWA.
The study of information extraction based on diffraction enhanced imaging
Authors: Hu Chun-Hong  , Li Hui  , Luo Shu-Qian  , Wang Xue-Yan  , Zhang Lu  ,   (1)首都医科大学生物医学工程学院,北京  100069; (2)首都医科大学生物医学工程学院,北京  100069；中国科学院自动化研究所模式识别国家重点实验室,北京  100190
Published: December 2020

Diffraction enhanced imaging （DEI） is a powerful phasesensitive technique that generates improved contrast of soft tissues compared to the conventional Xray imaging. In this paper, an information extraction method is investigated based on diffraction enhanced imaging, which simultaneously produces three parametric images, depicting separately an object's projected Xray absorption, refraction and ultrasmallangle Xray scattering （USAXS） properties. The information extraction is resolved using analytic reconstruction formulae, and the quality of the obtained parametric images depends on the input images acquired at three distinct analyser crystal orientations. The stability of the reconstruction procedure is discussed using the condition number of matrix, and the theoretical maxima of the refraction angle and USAXS distribution width are given. Finally, validation studies are conducted by use of guinea pig cochleae DEI image.
A comparative study of the beam-width spreading and angular spread in atmospheric turbulence
Authors: Yang Ai-Lin  , Li Jin-Hong  , Lü Bai-Da  ,   四川大学激光物理与化学研究所，成都  610064
Published: December 2020

Taking the HermitecoshGaussian（HChG） beam as a typical example, the beamwidth spreading and angular spread of HChG beams propagating through atmospheric turbulence are throughly studied. The relative beamwidth and relative angular spread instead of the beamwidth and angular spread have been used to study the sensitivity of a beam to the effect of turbulence. It is found that the smaller the refraction index structure constant C2n is, the less the beamwidth spreading and angular spread of HChG beams are. The angular spread of HChG beams with larger beam orders m, n, smaller parameter Ω0 and smaller waist width w0 is less affected by turbulence. This conclusion also holds true for the beamwidth spreading of HChG beams for the case of the propagation distance is sufficiently long. The variation of the relative beamwidth of HChG beams versus Ω0 and w0 is analyzed if the propagation distance being not so long. The results are illustrated by numerical examples and the validity of the results is explained physically. The spreading of HermiteGaussian, coshGaussian and Gaussian beams in atmospheric turbulence can be treated as special cases of HChG beams.
M2 factor matrix for two-dimensional Hermite-Gaussian beam
Authors: Li Wei  , Chen Jian-Guo  , Feng Guo-Ying  , Huang Yu  , Li Gang  , Xie Xu-Dong  , Yang Huo-Mu  , Zhou Shou-Huan  ,   (1)四川大学电子信息学院，成都  610064; (2)四川大学电子信息学院，成都  610064；华北光电技术研究所，北京  100015; (3)中国工程物理研究院激光聚变研究中心，绵阳  621900
Published: December 2020

The M2 factor matrix for twodimensional HermiteGaussian field is proposed. By introducing coupled beams half width and coupled M2 factor, the M2 factor matrix of the mode after being rotated around the propagation axis by some angle has been derived theoretically in the same coordinate. The rules of change of parameters related to M2 factor matrix varying with the modes' rotation angle have been simulated numerically; and the track of M2 factor vectors versus the modes' rotation angle has been given. Calculation results are in good agreement with theoretically derived ones, which proves that by using M2 factor matrix, M2 factors of a HermiteGaussian mode after rotation by a certain angle can be related with those of the same mode before rotation. This method is universally applicable to the beam quality analysis for asymmetric higher Gaussian beams, and is very important in guiding the mesurement of beam quality in practice.
Inverse problem of optical parametric chirped pulse amplification
Authors: Zeng Shu-Guang  , Zhang Bin  ,   四川大学电子信息学院，成都  610064
Published: December 2020

A method for solving the inverse problem of optical parametric chirped pulse amplification, i.e., for a given shape of the output signal pulse, how to calculate the shape of the input signal pulse, is proposed. Based on numerical techniques such as split-step Fourier transform and fourth-order Runge-Kutta, the quantitative relation between the input signal intensity and the output signal intensity was obtained by numerical fitting. Taking the chirped Gaussian pulse and the shaping pulse with a certain shape as the required output signal pulse, the input signal pulse shape can be worked out by the inverse calculation. The results indicate that the inverse problem can be solved quickly and precisely with the method proposed in this paper, and this method is useful for pulse shaping.
Broadband tunable pulses in quasi-phase-matched crystal based optical parametric amplification
Authors: Liu Tao  , Gu Wan-Yi  , Shi Pei-Ming  , Yu Song  , Zhang Hua  ,   北京邮电大学光通信与光波技术教育部重点实验室，北京  100876
Published: December 2020

The influence of grating period and noncollinear geometry on the broadly tunable bandwidth of optical parametric amplification are investigated theoretically and numerically for quasiphasematched crystal. The concept of maximum grating period is proposed to achieve the phase matching and groupvelocity matching simultaneously in a wide range. By employing the maximum grating period, geometry Ⅰ is recommended due to the much wider signal tunable range compared with geometry Ⅱ. An expression is proposed to calculate the maximum grating period for congruent periodically poled LiNbO3 with 800 nm pump wave. A feasible scheme is presented to determine the working temperature and noncollinear angle α, maximize the tunable range and simplify the tuning by rotating angle θ only. Finally, the parametric bandwidth is studied with consideration of the influences of the maximum grating period and noncollinear geometry.
Numerical analysis for structure optimization of seven-core photonic crystal fibers
Authors: Fang Xiao-Hui  , Chai Lu  , Hu Ming-Lie  , Li Yan-Feng  , Wang Qing-Yue  ,   天津大学精密仪器与光电子工程学院，光电信息技术科学教育部重点实验室，天津  300072
Published: December 2020

The eigenvalue equation associated with seven-core photonic crystal fiber was derived from coupled-mode equation. Mode properties were analyzed by its eigenvalues and eigenvector. Using the frequency domain finite difference method, the relationship between fiber structure and coupling coefficient was fully discussed through changing the wavelength, hole pitch and core distance. Mode shaping and higher-order supermode cut off was realized. The results were helpful to the fiber structure design and in-phase supermode selection.
Research on the fiber-optic evanescent field sensor based on microfabvication and the effect of fiber length on its properties
Authors: Zhuang Xu-Ye  , Liu Yong-Shun  , Wang Shu-Rong  , Wu Yi-Hui  , Zhang Ping  ,   (1)中国科学院长春光学精密机械与物理研究所应用光学国家重点实验室，长春  130033; (2)中国科学院长春光学精密机械与物理研究所应用光学国家重点实验室，长春  130033；中国科学院研究生院，北京  100049
Published: December 2020

Evanescent wave fiber-optic sensors （EWFS） with acicular encapsulation were fabricated using silicon photolithography technology and silica wet-etching technology. This type of EWFS is small in size, consumes little reagent, suffers less from deformation during the detection process and also protects the sensors from pollution. The results obtained from the EWFS with different sensing fiber lengths were studied. The effect of the fiber length on the sensors absorbance were analyzed theoretically and experimentally. It was shown that the properties of the EWFS could be improved greatly by choosing suitable length of the sensing fiber, and the contribution of unit length of sensing fiber to the absorbance becomes less as the sensors total length becomes longer.
On the role of magnetic field intensity effects on the discharge characteristics of Hall thrusters
Authors: E Peng  , Han Ke  , Wu Zhi-Wen  , Yu Da-Ren  ,   (1)北京科技大学机械工程学院，北京  100083; (2)哈尔滨工业大学电气工程系，哈尔滨  150001; (3)哈尔滨工业大学能源科学与工程学院，哈尔滨  150001
Published: December 2020

We investigates the magnetic field intensity effects on the discharge characterization of Hall thrusters for optimization of the magnetic fields by varying the strength of magnetic fields with its topography holds constant （keep in "focusing" type）, and making an experimental study of the thruster's operating performance working in different regions of magneto-ampere curve through Langmuir probe, spectrograph, etc.. The results shows that when the magnitude of magnetic field intensity is less than its optimal value, near-wall conductivity gives priority to the activity that electrons traverse the magnetic field; contrarily, discharge current varying with magnetic field intensity abnormally, and existing electrons conductive theories are failed to explain this phenomenon.
A new method for investigating the conduction of ZnO-based varistor ceramics
Authors: Li Sheng-Tao  , Cheng Peng-Fei  , Yang Yan  , Zhang Le  ,   西安交通大学电力设备电气绝缘国家重点实验室，西安  710049
Published: December 2020

The IV characteristics of ZnOBi2O3, ZnOBi2O3MnO systems and commercial ZnO varistor ceramics were measured at temperatures in a wide range of -180?℃T<100?℃. It was found that experimental conductancetemperature curves under various currents can be theoretically reproduced by calculating conductance in parallel or series for mechanisms such as scattering mechanism, thermionic emission and tunneling effect. It was found that if the relation between a singlemechanism conductance and temperature obeys the exponential law with an exponent a little less than 1, then this mechanism will give rise to a high nonlinear exponent. The nonlinear exponent due to tunneling effect was 33, which was similar to the measured value of 43 for commercial ZnO varistor ceramics. This tunneling effect is active even at low electric field, especially in low temperature region.
An atomistic simulation of structural evolution and melting characteristics of Pt nanocrystal during continuous heating
Authors: Wen Yu-Hua  , Sun Shi-Gang  , Zhang Yang  , Zhu Zi-Zhong  ,   (1)厦门大学化学系，固体表面物理化学国家重点实验室，厦门  361005; (2)厦门大学物理系，理论物理与天体物理研究所，厦门  361005
Published: December 2020

Using molecular dynamics method with many-body potentials, we have studied the thermal stability and melting mechanism of platinum nanocrystal of truncated octahedron enclosed by {111} and {100} surfaces, and investigated its microstructure and shape by statistical radius and Lindemann index. The results show that the nanocrystal first shows shape changes at 1500 K, then transforms to a spherical one at 1700 K. The surface first shows the premelting behavior at 1500 K, and the melt completely into liquid state. The melting process starts from the surface into the interior at this temperature, resulting in the complete melting of the nanocrystal at 1730 K. The surface premelting is advantageous to shape transformation of octahedron-truncated nanocrystal.
Investigation of n-type GaN deposited on sapphire substrate with different small misorientations
Authors: Xing Yan-Hui  , Deng Jun  , Han Jun  , Li Jian-Jun  , Shen Guang-Di  ,   北京工业大学电子信息与控制工程学院，北京  100124
Published: December 2020

The ntype GaN films have been grown on cplane sapphire with different small misorientation（0°—03°）by metalorganic chemical vapor deposition. It was observed by atomic force microscopy that the ntype GaN has the step flow growth mode, the flow steps of the ntype GaN surface are uniformly distribution on 02° and 03° misorientation sapphire substrate, it was observed clearly that random and poor distribution of the flow steps was caused by the step reconstruction on 0° misorientation sapphire substrate. The image quality parameter of electron backscatter diffraction indicated that the strains increase as the ntype GaN epilayer thickness increases on 0° misorientation sapphire substrate but do not vary obviously on 02° and 03° misorientation sapphire substrates. Electrical and optical properties demonstrated the ntype GaN grown on the 02° and 03° misorientation sapphire substrates have higher electron concentration and lower ratio of the intensity of yellow band to near band edge.
Terahertz power dissipation spectra of electrons in bulk GaAs under high electric fields at low temperature
Authors: Zhu Yi-Ming  , Kaz Hirakawa  , Chen Lin  , He Bo-Yong  , Huang Yuan-Shen  , Jia Xiao-Xuan  , Zhang Da-Wei  , Zhuang Song-Lin  ,   (1)日本东京大学生产技术研究所，东京都  153-8505; (2)上海交通大学微电子学院，上海  200240; (3)上海理工大学上海市现代光学重点实验室，上海  200093; (4)上海理工大学上海市现代光学重点实验室，上海  200093；上海交通大学微电子学院，上海  200240；日本东京大学生产技术研究所，东京都  153-8505
Published: December 2020

By using the freespace terahertz （THz） electrooptic （EO） sampling technique, the THz electromagnetic wave waveforms emitted from intrinsic bulk GaAs photoexcited by femtosecond laser pulses under strong bias electric fields up to 300 kV/cm were recorded. From the experimental data, we can clearly see the THz electromagnetic wave emission waveforms, ETHz（t）, which are proportional to the acceleration/deceleration of electrons, have a bipolar feature. Power dissipation spectra of electrons for stepfunctionlike input electric fields have been obtained by calculating Fourier spectra of the measured THz traces. The cutoff frequency, νc, for negative power dissipation （i.e., gain） due to intervalley transfer is found to gradually increase with increasing bias electric fields, F0, for F0 < 50 kV/cm and saturate at 750 GHz above ～50 kV/cm at 10 K.
Texture and electrical transport properties of Ba and Ag double substituted BaxAgyCa3-x-yCo4O9 oxide
Authors: Zhang Fei-Peng  , Lu Qing-Mei  , Zhang Jiu-Xing  , Zhang Xin  ,   北京工业大学材料科学与工程学院,新型功能材料教育部重点实验室，北京  100124
Published: December 2020

Doublesubstituted BaxAgyCa3-x-yCo4O9 bulks were fabricated by nitric acid solgel and spark plasma sintering, and the phase composition, orientation, texture and electrical transport properties of the bulks were investigated by means of X-ray diffraction,scanning electron microscope and electrical resisitivity measurement. The result shows that silver which does not belong to the stoichiometric compounds BaxAgyCa28Co4O9 is distributed in the matrix. The degree of orientation increases with increasing ratio of Ba to Ag for the doublesubstituted bulk. The orientation of BaxAgyCa28Co4O9 （y>0） bulks is prominently lower than that of Ca3Co4O9 and the orientation of Ba02Ca28Co4O9 bulk is higher than that of Ca3Co4O9 bulk. The electrical transport mechanism of the bulk with x=y=01 is changed slightly. The Ba01Ag01Ca28Co4O9 bulk exhibits simultaneously lowered orientation and moderately low resistivity and the resistivity reaches 73 mΩ·cm at 973 K. The Ag02Ca28Co4O9 bulk exhibits lowest orientation and lowest resistivity, reaching 63 mΩ·cm at 973 K.
Effect of phosphor-doping on optical properties of BaMgAl10O17:Mn2+
Authors: Liao Qiu-Rong  , Hu Yun-Sheng  , Liu Rong-Hui  , Liu Yuan-Hong  , Teng Xiao-Ming  , Xia Tian  , Zhuang Wei-Dong  ,   北京有色金属研究总院稀土材料国家工程研究中心，有研稀土新材料股份有限公司，北京  100088
Published: December 2020

The diammonium phosphate was added as start material to synthesize Pdoped BaMgAl10O17:Mn2+ phosphors, which were prepared by high temperature solid state technology. The effect of Pdoping on the structure, morphology and luminescent properties of BaMgAl10O17:Mn2+ were determined by Xray diffraction, scanning electron microscopy, Fouriertransform infrared spectroscopy, energy dispersive Xray spectroscopy and vacuum ultraviolet （VUV） spectra. The results show that P doping is conducive to the crystallization of the phosphors and improving the morphology. The lattice parameters become smaller when the phosphor is doped with P. The P doping makes the emission spectra to blueshift and the CIE x value to decrease. At appropriate P concentration, the absorption of the matrix in VUV range is improved, and the emission intensity under VUV excitation is enhanced.
Experimental study on the properties of the AR-coated external cavity diode lasers
Authors: Liu Si-Ping  , Zhang Yu-Chi  , Zhang Peng-Fei  , Li-Gang  , Wang Jun-Min  , Zhang Tian-Cai  ,   量子光学与光量子器件国家重点实验室，山西大学光电研究所，太原 030006
Published: December 2020

The properties of the Anti-Reflection coated (AR-coated) GaAs diode lasers are investigated systematically in Littrow configuration. The tuning range of about 30 GHz is obtained without any mode-hops by the current compensation technique. Using a heterodyne detection technique, the linewidth of the AR-coated ECDL is measured, which is about 120 kHz. We also investigate the intensity noise of the AR-coated ECDL as a function of the current and the wavelength. The relations between the intensity noise of the ECDL and the driving current and wavelength are obtained and analyzed. This laser system can be used in many areas, such as atomic physics, laser spectroscopy and quantum optics, etc.
Long-range correlation of extreme events in meterorological field
Authors: Feng Guo-Lin  , Gong Zhi-Qiang  , Hou Wei  , Wang Qi-Guang  , Zhi Rong  ,   (1)扬州大学物理科学与技术学院，扬州  225002; (2)扬州大学物理科学与技术学院，扬州  225002；中国科学院大气物理研究所东亚区域气候-环境重点实验室，北京  100029; (3)扬州大学物理科学与技术学院，扬州  225002；中国科学院大气物理研究所东亚区域气候-环境重点实验室，北京  100029；国家气候中心，中国气象局气候研究开放实验室，北京  100081; (4)中国科学院大气物理研究所东亚区域气候环境重点实验室，北京  100029；国家气候中心，中国气象局气候研究开放实验室，北京  100081
Published: December 2020

The long range correlation of extreme events of the Lorenz system is discussed by using the method of fixed threshold. It turns out that all of the extreme events with different threshold have long range correlation. The scaling exponents are similar, but just smaller than the original series. The long range correlation of extreme events is less effected by the initial value changes, but it decreases distinctly when the parameters increases. The long range correlation of Lorenz systems extreme events series has the traits of memory when compared with Gaussian white noise. Finally, we use the maximal day air temperature data of 194 stations between 1957 and 2004, from the National Climate Center of China, to reveal that the similar law exists in the actual meteorological factors.
Finite precision function theory and photon solution of Einstein-Maxwell equations
Authors: Chen Guang  ,   东华大学信息科学与技术学院，上海  201620
Published: December 2020

This paper puts forward the finite precision function theory. Based on the function theory, a photon solution of finite precision Einstein-Maxwell equations is founded, and the important properties of electromagnetism, gravitation and space-time geometry of the classical photon are revealed.
Stochastic resonance under modulated noise in linear systems driven by dichotomous noise
Authors: Ning Li-Juan  , 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

Stochastic resonance （SR） is studied in linear systems under modulated noise when the modulated noise is a linear combination of multiplicative and additive noise.The exact expression of the first two moments and signal-to-noise ratio（SNR） are obtained.We find the bona fide SR, conventional SR and SR in the broad sense. Both resonance and suppression appear in the bona fide SR. Moreover,choosing mutilplicative and additive noise as modulated noise can enhance SNR for different degrees of cross correlation.
Analytic solution for a class of generalized Sine-Gordon perturbation equation
Authors: Mo Jia-Qi  ,   安徽师范大学数学系,芜湖  241000；上海高校计算科学E-研究院上海交通大学研究所,上海  200240
Published: December 2020

Using the homotopic mapping method, a class of generalized Sine-Gordon equation is obtained. Firstly, by introducing a homotopic mapping, the homotopic mapping solution for original equation is constructed. The analytic solution for the problem is finally obtained.