bluuebunny/crossref_metadata_2025 huggingface dataset:
Residual stress measurement of porous silicon thin film by substrate curvature method
Authors: Di Yu-Xian  , Ji Xin-Hua  , Hu Ming  , Qin Yu-Wen  , Chen Jin-Long  ,   (1)天津大学电信学院电子科学与技术系,天津  300072; (2)天津大学机械工程学院力学系,天津  300072
Published: December 2020

An optical apparatus based on substrate curvature method was developed for stress measurement of thin films, which offeres such advantages as overall field, non-contact, high precision, nondestructive, easy operation and quick response. Using the apparatus, the residual stress in porous silicon (PS) layers prepared by electrochemical etching using a solution of HF/ethanol with composition ratio of 1∶1 on heavily or gently doped (100) silicon as a function of the electric current density were obtained. It is found that the residual tensile stress tends to increase with the porosity increasing and the doping concentration of the silicon wafer increasing. The results show that there is a deep connection between the micro-structure PS and the residual stress distribution.
Hydeogen-related defect sites in ZnO studied via local vibrational modes
Authors: Wu Yu-Yu  , Zou Chong-Wen  , Xu Peng-Shou  ,   中国科学技术大学国家同步辐射实验室,合肥  230029
Published: December 2020

By employing the full potential augmented plane wave and local orbital method (APW+lO), we studied some possible hydrogen-related defect sites in ZnO. In view of the calculated defect formation energy, the most possible defect site should inhabit BC∥ local structure position. But the calculated local vibrational modes (LVMs) of the defect sites, when compared with the infrared absorption result, leads to the conclusion that the hydrogen-related defect sites in ZnO can inhabit both BC∥ and ABo∥ local structure positions.
Spin dynamics in quasi-one-dimensional strongly correlated zigzag materials
Authors: Qin Ji-Hong  , Xu Su-Fen  , Feng Shi-Ping  ,   (1)北京师范大学物理系，北京  100875; (2)北京师范大学物理系，北京  100875;北京科技大学应用科学学院物理系，北京  100083
Published: December 2020

Within the t-J model, the spin dynamics of the quasi-one-dimensional strongly correlated zigzag type materials is studied based on the fermion-spin theory. It is shown that the pattern of the neutron scattering peaks depends on both the next-nearest neighbor coupling and doping. The weight of the incommensurate neutron scattering peaks decreases with increasing energy.
Optimization of SFRFQ flake-electrode design
Authors: Wang Zhi  , Chen Jia-Er  , Yan Xue-Qing  , Lu Yuan-Rong  , Guo Zhi-Yu  , Fang Jia-Xun  , Zhu Kun  ,   北京大学重离子物理研究所，北京  100871
Published: December 2020

The simulated and measured electric field distributions along the separated function radio frequency quadrupoles(SFRFQ) are presented in this paper. Based on the simulations, the parameters of flake-electrode and the effective gap voltage gain have been optimized. As a design example, one set of SFRFQ electrode with 5 periods and inter-electrode voltage 70 kV is designed to accelerate O+ from 1MeV to 1.5MeV.
Virasoro symmetry subalgebra, multi-linear variable separation solutions and localized excitations of higher-dimensional differential-difference models
Authors: Shen Shou-Feng  ,   浙江工业大学数学系,杭州  310014
Published: December 2020

Seeking for higher-dimensional integrable models is important in nonlinear science. By using the infinite dimensions Virasoro symmetry subalgebra［σ(f1),σ(f2)］=σ(f′1f2-f′2f1) and prolongation theory, many higher-dimensional models can be derived. By means of a concrete realization, some higher-dimensional differential integrable models with infinite dimensions Virasoro symmetry subalgebra can be obtained. In this paper, this method is extended to obtain differential-difference models and a (3+1)-dimensional Toda-like lattice which is week multi-linear variable separation solvable (MLVSS) model is derived. In addition, this model can be symmetry reduced to a (2+1)-dimensional special Toda lattice which is a MLVSS model. A (1+1)-dimensional MLVSS Toda lattice also can be obtained. Because some arbitrary functions are included, abundant new localized excitations such as dromion solution, lump solution, ring soliton, breather instanton et al can be found by selecting appropriate functions.
Eigenactions and eigenvalues of volume operator on any-valent vertices
Authors: Shao Liang  , Shao Dan  , Shao Chang-Gui  , Zhang Zu-Quan  ,   (1)江汉大学物理与信息工程学院物理系，武汉  430056; (2)武汉科技大学理学院应用物理系,武汉  430081
Published: December 2020

Antisymmetrizing the actions of hand triple contained in volume operator and grasping on the segments rooting through any-valent vortex of spin netwok, and using the binor identity, a proof is given that all these actions are eigenactions with eigenvalue -2. A systematic algebraic method to calculate the eigenvalues of volume operator for any-valent vortices is given, and the general and algebraic expressions of volume eigenvalues for 3-, 4-, 5-, 6- valent vertices are obtained.
Chaos control of ferroresonance system based on improved RBF neural network
Authors: Sima Wen-Xia  , Liu Fan  , Sun Cai-Xin  , Liao Rui-Jin  , Yang Qing  ,   重庆大学高电压与电工新技术教育部重点实验室，重庆  400044
Published: December 2020

Facing to the ferroresonance over voltage of neutral grounded power system, an improved learning algorithm based on RBF neural networks is used to control the chaos system. The algorithm optimizes the object function to derive learning rule of central vectors, and uses the clustering function of network hidden layers.It improves the regression and learning ability of neural networks. The academic derivation testifies the errors and precision could satisfy demand of chaos control.And simulation calculation also displayed that the rate of convergence of the improved RBF neural network is much quickly and approach ability is much stronger. The numerical experimentation of ferroresonance system testifies the reliability and stability of using the algorithm to control chaos in neutral grounded power system.
A simplified model for computing state equation of argon plasma
Authors: Wang Cai-Xia  , Tian Yang-Meng  , Jiang Ming  , Cheng Xin-Lu  , Yang Xiang-Dong  , Meng Chuan-Min  ,   (1)北京信息工程学院，北京  100101; (2)四川大学原子分子物理研究所，成都  610065; (3)西南民族大学物理系，成都  610064; (4)中国工程物理研究院，绵阳  621900
Published: December 2020

In this paper, We first fitted the numerical results of the ionization potential calculated by Thomas-Fermi statistical model and gained the analytical function of the potential versus the degree of ionization, then calculated the ionization potential and the average degree of ionization for argon versus temperature and density in local thermal equilibrium (LTE) case. The curve of pressure versus specific volume V of argon plasmas is calculated according this simplified model. The calculated results by this simplified model are in agreement with experimental data and the calculated results of the Saha-equation theory. This simplified model can be used to the calculation of the equation of state of plasmas mixture and is expected to be widely used in the field of EML technology involving the strongly ionized plasmas.
Electron holography determination of the growth polarity of GaN/AlGaN multi-quantum well structure
Authors: Dai Tao  , Liu Yu-Zi  , Zhang Ze  ,   (1)北京工业大学，北京  100022; (2)北京凝聚态物理国家实验室，中国科学院物理研究所北京电子显微镜实验室，北京  100080
Published: December 2020

A method to determine the growth polarity of GaN/AlGaN multi-quantum wells (MQWs) has been proposed. Electron holography (EH) study of the potential profiles of the multi-quantum well structure has been used here to determine the direction of build-in electric field that is strictly related to the growth polarity.
Research on the submicron domain inversion structure of MgO:LiNbO3
Authors: Yan Wei-Guo  , Chen Yun-Lin  , Wang Dong-Dong  , Guo Juan  , Zhang Guang-Yin  ,   (1)教育部弱光非线性光子学材料先进技术及制备实验室，南开大学物理学院，天津  300071; (2)教育部弱光非线性光子学材料先进技术及制备实验室，南开大学物理学院，天津  300071；晶体材料国家重点实验室，山东大学，济南  250100
Published: December 2020

We have investigated the periodic poling characteristics of MgO: LiNbO3 and properties of the domain wall velocity. Based on back-switching reaction, domain-inverted velocity can be accurately controled by multi-impulse electric field, which can be used to fabricate MgO: LiNbO3 with submicron uniform periodical structure. At the same time, we studied the cause of formation and the mechanism of submicron domain-inverted structure.
Good performance of chirped fiber Bragg gratings obtained by asymmetrically one-side exposure apodization
Authors: Liu Yan  , Zheng Kai  , Tan Zhong-Wei  , Li Bin  , Chen Yong  , Ning Ti-Gang  , Jian Shui-Sheng  ,   北京交通大学光波技术研究所，北京  100044
Published: December 2020

The generation of group delay ripple and reflection sideband is explained by the oscillazation theory. And the effect of non-constant change of averaged index modulation induced by the one-side exposure apodization on the characteristics of chirped gratings is analyzed for the first time. The mechanism of apodization to enhance the performance of chirped fiber Bragg gratings is studied also. Based on the study, a simple apodization method to improve the performance of chirped fiber gratings is proposed, in which only one-sided exposure is needed which is easy to realize.
Study of the band-structure and the uncoupled modes in two-dimensional phononic crystals with the multiple-scattering theory
Authors: Cai Li  , Han Xiao-Yun  ,   国防科技大学机电工程研究所，长沙  410073
Published: December 2020

The multi-scattering theory (MST) method is applied to study the band structure of the two-dimensional phononic band-gap material. A comprehensive study is performed for the coupling between various order components of the cylindrical scattered wave. It has been found that there are decoupling effects at the edge of the band gap. Therefore, a self-contained self-consistent multiple scattering model of the zeroth-order scattered wave is obtained at the edge of the first band gap. A Mie scattering factor and a lattice structure factor are introduced to give a physical insight into the variation of the gap’s starting frequency by graphic analytic method.
Spectroscopic study on the air plasma induced by delayed dual laser pulses
Authors: Lin Zhao-Xiang  , Wu Jin-Quan  , Gong Shun-Sheng  ,   (1)中国科学院武汉物理与数学研究所，波谱与原子分子物理国家重点实验室，武汉  430071; (2)中南民族大学电信学院，武汉  430074
Published: December 2020

By using a two laser beam method, the spectra of laser-induced air plasmas (LIAP) were studied experimentally. Two laser beams of a laser were used in the experiment. One of the beams was used to create the plasmas, which is called the ionizing-laser-beam (ILB), and the other beam was used to give influence to the plasmas, called action-laser-beam (ALB). This paper reports the experimental results and give a preliminary analysis of the modifications to the spectral characteristics due to the influence of the ALB. The experimental results indicated that the total spectral intensity of laser-induced air plasmas increased obviously under the action of the ALB. The increment of continuous spectra was greater than that of the line spectra; the increment of the short wavelength band was greater than that of the long wavelength band. The longer the delay-time of ALB behind the ILB, the larger the increase of spectra intensities. There is no threshold for the ALB to increase the laser-induced air plasmas spectral intensity. The results also showed that besides increasing the intensity, the decay-time for most of lines would increase under the influence of ALB. The preliminary analyses indicated that the results may be caused by electrons in the plasma which transfer their energy absorbed from the ALB via different routs with different efficiencies. These results provides some new sight into the microscopic mechanisms of the decay of laser-induced air plasmas, and also provides some experimental evidences for prolonging the decay-time of laser-induced air plasmas for some technical applications.
Spectral hyper-fine structure and zero-field splitting parameters with Jahn-Teller effect of CsNiCl3 crystal
Authors: Yin Chun-Hao  , Jiao Yang  , Zhang Lei  , Song Ning  , Ru Rui-Peng  , Yang Liu  ,   中国矿业大学理学院，徐州  221008
Published: December 2020

The complete diagonalized Hamiitonian matrixes of 3d2/3d8 ion configuration with trigonal symmetry have been established by irreducible representation method. The spectral hyper-fine structure and the constants of crystal structure and zero-field splitting parameters of CsNiCl3 crystal, as well as the Jahn-Teller effect and the influence of the spin singlet on the ground levels of Ni2+ ion have been studied. The results agree with the experimental facts. Besides, taking into account the influence of the spin-spin (SS) coupling interactions and the Trees correction which were neglected in previous publications, we find that the zero-field splitting parameters arise from four mechanisms, namely: (1) Spin-orbit coupling mechanism; (2) Spin-spin coupling mechanism; (3) Spin-orbit and spin-spin combined coupling mechanism; (4) Spin-orbit and Trees correction combined coupling mechanism. The spin-orbit coupling mechanism is the most important one and the other three mechanisms can not be neglected.
Study on the large grain size poly-Si prepared by metal induced crystallization using nickel chemical source
Authors: Zhao Shu-Yun  , Wu Chun-Ya  , Liu Zhao-Jun  , Li Xue-Dong  , Wang Zhong  , Meng Zhi-Guo  , Xiong Shao-Zhen  , Zhang Fang  ,   (1)科技部高技术研究发展中心，北京  100044; (2)南开大学光电子所，天津市光电子薄膜器件与技术重点实验室，教育部光电子信息科学与技术重点实验室，天津  300071
Published: December 2020

Nonv-electrical plating was employed to form nickel inducing source on the surface of α-Si thin film deposited by VHF-PECVD. It was observed that the nickel inducing source formed by this method appeared as “dots” uniformly distributed on the surface of a-Si thin film after annealed for several hours at 550℃. The quantity of “dot” on the a-Si was determined by Ni concentration in the solution, the PH value, and the plating times, etc. The lateral crystallization was observed if the density of “dots” is relatively low. Poly-Si with maximum grain size of 90μm was obtained from the original α-Si deposited by VHF-PECVD. High performance thin film transistor (TFT) monitors were fabricated using this poly-Si.
Study of nanoscale banded 90° domain patterns and pyroelectric properties in (111) oriented (Pb,La)TiO3 thin films
Authors: Liu Hong  , Pu Zhao-Hui  , Gong Xiao-Gang  , Wang Zhi-Hong  , Huang Hui-Dong  , Li Yan-Rong  , Xiao Ding-Quan  , Zhu Jian-Guo  ,   (1)电子科技大学微电子与固体电子学院，成都  610054; (2)四川大学材料科学与工程学院，成都  610064
Published: December 2020

Lanthanum doped lead titanate (PLT) ferroelectric thin films were grown on Pt/Ti/SiO2/Si(100) substrates using RF magnetron sputtering. X-ray Diffraction (XRD) was applied to study crystalline properties of PLT films, and XRD patterns of PLT thin films show that there appeared (111) preferred-oriented tetragonal perovskite phase. The ferroelectric domain patterns and the corresponding topography of PLT thin films have been investigated using piezoresponse force microscopy (PFM) and atomic force microscopy (AFM), respectively. PFM observations show that there exist nanoscale banded 90° domain patterns 20 to 60 nm in width and low energy head-to-tail polarization configurations in PLT film. The relationship between fabricating conditions and properties of PLT10 thin films was studied. It was found that PLT10 thin film fabricated under the optimized conditions possess dielectric constant εr=365, dielectric loss tgδ=0.02, and pyroelectric coefficient γ=2.18×10-8C·(cm2·K)-1, respectively. The PLT thin films could meet the needs for uncooled pyroelectric infrared sensors.
The study of a cellular automaton NS and WWH mixed model for traffic flow on a two-lane roadway
Authors: Wu Ke-Fei  , Kong Ling-Jiang  , Liu Mu-Ren  ,   广西师范大学物理与信息工程学院，桂林  541004
Published: December 2020

Based on the NS model and the WWH model for one-dimensional cellular automaton traffic flow, and taking into account the drivers adopting different driving rules, we present a cellular automaton NS and WWH mixed model for traffic flow on a two-lane roadway. By using numerical simulation, we study the effect of the mixed proportion coefficient fNS on the velocity-density and flow-density diagrams of the mixed traffic flow and the lane-change frequency of the vehicles.
Time-resolved two-photon excitation fluorescence spectroscopy
Authors: Liu Li-Xin  , Qu Jun-Le  , Lin Zi-Yang  , Chen Dan-Ni  , Xu Gai-Xia  , Hu Tao  , Guo Bao-Ping  , Niu Han-Ben  ,   (1)深圳大学光电子学研究所，深圳   518060; (2)深圳大学光电子学研究所，深圳   518060;中国科学院西安光学精密机械研究所，西安  710068;中国科学院研究生院，北京  100049
Published: December 2020

A novel time-resolved two-photon excitation fluorescence spectroscopic system based on a high repetition rate streak camera and capable of simultaneous measurement of fluorescence spectrum and lifetime of the samples is presented. The system has high temporal (6.5—200 ps) and spectral (1—3 nm) resolutions and permits rapid data acquisition and reliable and reproducible lifetime and spectrum determinations. The system is tested with standard fluorescent dyes (rhodamine 6G, coumarin 314 and their mixtures) and the lifetimes and spectra obtained agree well with those reported in the literatures. Experimental results indicate that our system provides a unique contrast mechanism for discriminating multi-fluorophore or multi-component of biological tissues through spectrally and temporally resolved information and may find extensive applications in multispectral fluorescence lifetime imaging and fluorescence resonance energy transfer imaging.
Relation between dynamic parameters and limiting current in separated function radio frequency quadrupole accelerator
Authors: Wang Zhi  , Chen Jia-Er  , Yan Xue-Qing  , Lu Yuan-Rong  , Fang Jia-Xun  , Guo Zhi-Yu  ,   北京大学重离子物理研究所，北京  100871
Published: December 2020

The particles' motion in separated function radio frequency quadrupole (SFRFQ) accelerator is analyzed in this paper. Compared to conventional radio frequency quadrupole accelerator, the SFRFQ structure has higher accelerating efficiency, and the particles are focused or defocused by the quadrupole outside the diaphragms. The relation between limiting current and dynamic parameters has been deduced, so the transverse and longitudinal stability of particles in SFRFQ is ensured by selecting proper dynamic parameters.
Potentional energy function of CrHn(n=0,+1,+2)
Authors: Huang Ping  , Zhu Zheng-He  ,   (1)四川大学原子分子物理研究所，成都  610065; (2)四川师范大学化学与材料科学学院，成都  610066
Published: December 2020

Based on the atomic and molecular reaction statics, the ground electronic states of CrH(X6Σ+), CrH+(5Σ+), CrH2+ (6Σ+) and their dissociation limits have been derived. Using density functional method (B3PW91), 6-311++G** basis sets for H and split valence polarization basis sets for Cr, the molecular equilibrium geometry and dissociation energies for CrH+(5Σ+) and CrH2+ (6Σ+) have been calculated. The analytical potential energy functions for CrH(X6Σ+), CrH+(5Σ+) and CrH2+ (6Σ+) are determined. The force fields and spectroscopic parameters have been worked out from these analytical potential energy functions. For the ground state of CrH+, the calculated results of Re, f2, f3, f4, Be, αe, ωe and ωeχe are 0.16200 nm, 1.52574 aJ/nm2, -7.81171 aJ/nm3, 28.61613 aJ/nm4, 6.71181, 0.28792, 1624.6297 and 53.55394 cm-1, respectively; and for the ground state of CrH2+, the corresponding parameters are 0.24005 nm, 0.42946 aJ/nm2, -0.97766 aJ/nm3, 2.40438 aJ/nm4, 2.9562, 0.050184, 858.059 and 6.46813 cm-1, respectively. The theoretical results show minimum points in the potential energy curves of CrH+(5Σ+) and CrH(X6Σ+), so we conclude that CrH(X6Σ+) and CrH+(5Σ+) are stable.But there are no minimum points in the potential energy curves of CrH2+ (6Σ+), so CrH2+ (6Σ+) is not stable.
Study on potential energy functions and spectrum constants of VOn±(n=0,1,2)
Authors: Du Quan  , Wang Ling  , Shen Xiao-Hong  , Gao Tao  ,   (1)四川大学原子与分子物理研究所,成都  610065; (2)西华大学应用化学研究所,成都  610039; (3)西华大学应用物理研究所,成都  610039; (4)西华大学应用物理研究所,成都  610039;四川大学原子与分子物理研究所,成都  610065
Published: December 2020

The potential energy functions and spectrum constants of VOn±(n=0,1,2) have been analyzed by the density functional method (B3LYP/6-311++G(d, p) and using the relativistic effective core potential (Lanl2dz). The results show that all of them can exist stably. Their ground electronic states are 4Σ (VO2-), 3Σ (VO-), 4Σ(VO), 3Σ(VO+) and 2Σ(VO2+). Among them, the potential energy curves of VO2+ and VO2- have the form of a volcanic crater. The molecules of VO2+ and VO2- are in meta-stable states. The potential energy curves of VO2+ and VO2- have been fitted with the seven-parameter Murell-Sorbie functions. It has been found that the fitting cures of the meta-stable ions VO2+ and VO2- are well in accordance with their potential energy curves. However, the four-parameter Murell-Sorbie functions are not suitable for VO2+ and VO2-. At the same time, the effect of charge on the potential energy functions and energy levels have been discussed.
Investigation on the miniaturization of the microstrip antenna based on the back ward wave property of left-handed medium
Authors: Wu Ming-Feng  , Meng Fan-Yi  , Wu Qun  , Wu Jian  ,   (1)哈尔滨工业大学电子与信息技术研究院，哈尔滨  150001; (2)哈尔滨工业大学电子与信息技术研究院，哈尔滨  150001;电波环境特性及模化技术国防科技重点实验室，北京  102206
Published: December 2020

Based on a left-handed medium (LHM) structure unit with smooth dispersion, broadband property and of electrical small dimensions, a microstrip antenna (MSA) substrate is designed partially loaded by both the LHM and the conventional dielectric medium for the miniaturization of MSAs, in which the backward wave property of LHM is employed to compensate for the phase shift resulting from waves propagating in the conventional dielectric medium. Both the analytical and numerical results demonstrate that the physical dimensions of a 4.70 GHz MSA have been significantly reduced by 37.92%, and can be no longer proportional to the working wavelength, while its bandwidth and gain can be equivalent to that of a conventional MSA. All above results indicate the practical capability of LHM in the miniaturization of MSAs.
Hydrodynamic model of transient Ni-like X-ray lasers driven by Gaussian laser pulse
Authors: Pang Hai-Long  , Li Ying-Jun  , Lu Xin  , Zhang Jie  ,   (1)中国科学院物理研究所,北京  100080; (2)中国矿业大学(北京)理学院,北京  100083; (3)中国矿业大学(北京)理学院,北京  100083;中国科学院物理研究所,北京  100080
Published: December 2020

The self-similarity model of hydrodynamics of transient collisional excitation X-ray lasers is modified for drive laser pulse with a Gaussian temporal profile. The results show that the modified model can more accurately describe the hydrodynamic process of tramsient collision emission X-ray laser than the self-similarity model. Using the modified model, the experimental design of the Ni-like Mo X-ray lasers is optimized.
Intelligent control of video monitoring system based on the color histogram analysis
Authors: Zhang Bian-Li  , Chang Sheng-Jiang  , Li Jiang-Wei  , Wang Kai  , Shen Hui-Ting  , Zhang Yan-Xin  , Zhai Hong-Chen  ,   (1)解放军炮兵学院,合肥  230031; (2)南开大学出版社,天津  300071; (3)南开大学现代光学研究所,光电信息技术科学教育部重点实验室,天津  300071
Published: December 2020

The intelligent control of video monitoring system in a fixed background scene is realized by comparing color histogram distance between reference image and objective image. The impacts on reference images caused by the variation with time and sunlight are eliminated by renewing reference images on-line. In order to reduce computational complexity and speed up the processing, a uniform compressional algorithm of real color space based on fuzzy method is proposed. The simulations show that an image can be processed in 10 ms, which meets the requirement of real-time processing.
The hole burning and optical bistability of quasi-Λ-type four-level atom system
Authors: Chen Jun  , Liu Zheng-Dong  , You Su-Ping  ,   (1)南昌大学近代物理研究所，南昌  330047;杭州电子科技大学物理系，杭州  310018; (2)南昌大学近代物理研究所，南昌  330047;南昌大学纳米技术工程研究中心，南昌  330047
Published: December 2020

In this paper we study the quantum interference effects of a quasi-Λ-type four-level atom system interacting with two light fields. When the probe field is weak, our calculations show that along with the change of Rabi frequencies of the driving field, the system appears to be hole burning in the dispersion curve,and two big electromagnetic induced transparency windows with approximately the same width are demonstrated. In addition, the evolution of dispersion with the Rabi phase of probe field shows optical bistability.
Experimental research of coherent combining of three fiber amplifiers
Authors: Xiao Rui  , Hou Jing  , Jiang Zong-Fu  , Liu Ming  ,   国防科学技术大学光电科学与工程学院，长沙  410073
Published: December 2020

Combining coherent laser beams is an important and challenging area of laser science and is now still in a state of laboratory. We have succeeded in the coherent combination of three-element fiber-laser array based on ytterbium-doped polarization-maintaining single-mode power amplifiers with good experimental results. In this paper, we introduce the experimental setup and detailedly describe the method of measurement and control of phase noise. A single signal arm is taken as example, the measured phase noise are presented. At last, we give the results of coherent combination in the far field and briefly discuss a few factors having effect on the far field properties. We conclude that the combining method can be scaled to a large number of lasers.
Harmonic velocity noise and its frequency resonance with the potential
Authors: Song Yan-Li  ,   天津大学理学院，天津  300072
Published: December 2020

A noise with frequency structure, i.e. the harmonic velocity noise is investigated to describe the complicated noise environment. We studied the noise's occurrence, correlation function, power spectrum, as well as some behaviors caused by its frequency characteristics when it acts as a thermal noise. The results show that the harmonic velocity noise is band-passing in frequency spectral space with a peak frequency and the band width is determined by Γ. If a Brownian particle in a harmonic potential is driven by a thermal harmonic velocity noise, its maximum energy appears when the two frequencies are equal. This testifies that there is a dynamical resonance between the frequencies of the noise and the potential, which controls the particle's energy.
Single crystal growth and magnetic properties of strong geometric frustrated magnetic pyrochlore Dy2Ti2O7
Authors: Tang Zheng  , Li Chang-Zhen  , Yin Di  , Zhu Ben-Peng  , Wang Li-Li  , Wang Jun-Feng  , Xiong Rui  , Wang Qu-Quan  , Shi Jing  ,   (1)武汉大学物理系，武汉  430072; (2)武汉大学物理系，武汉  430072;中国科学院国际材料物理中心，沈阳  110016;武汉大学声光材料与器件教育部重点实验室，武汉  430072
Published: December 2020

Large, high quality single crystals of Dy2Ti2O7 have been successfully grown by the floating zone technique in an infrared image furnace. The obtained single crystal has been characterized by X-ray diffraction at room temperature and is shown to have the face centred cubic structure, Fd3m, with a room temperature lattice parameter a＝1.0112(2) nm. The full-width at half-maximum of rocking curves of ［111］ and ［400］ Bragg peaks are 0.07° and 0.05°, respectively. Magnetic susceptibility measurements give a Van Vleck paramagnetic parameter of 2.46×10-5m3/mol, the effective moment μeff＝10.24(4)μB and Cure-Weiss temperature ΘCW＝1.1 K, indicating weak ferromagnetism for the Dy2Ti2O7 single crystal. The comparative studies of the experiment and theoretical analysis reveal that the long-ranged dipole-dipole interactions dominate the magnetic behaviors of this kind of spin ice system, and the dipolar energy scale Dnn=3.00 K.
Study of the stability of gallium-arsenic ion clusters
Authors: Yang Jian-Song  , Li Bao-Xing  ,   杭州师范学院物理系，有机硅化学及材料技术教育部重点实验室，微流控芯片研究所，杭州  310036
Published: December 2020

Using full-muffin-tin-orbital molecular-dynamics method, the electronic and geometric structures of GanAsn (n=4,5,6) ion clusters and their stability have been investigated in detail. The lowest energy structures are found. Our calculations suggest that they are obviously different from the ground state structures of their corresponding neutral clusters. In addition, the stable ionic structures have more severe structural distortion than the neutral structures. Gallium atoms occupy the cap atom positions more easily than arsenic atoms in the mixed GanAsn clusters.
Virtual-crystal doping study in novel superconductor MgCNi3
Authors: Ma Rong  , Zhang Jia-Hong  , Du Jin-Li  , Liu Su  , Liu Mei  ,   东南大学物理系，南京  210096
Published: December 2020

Using full potential linearized augmented plane wave method and considering local spin density approximation, we study superconducting and magnetic properties in virtual-crystal doped MgCNi3. The electronic band structure, bulk modulus and its pressure derivative, magnetic moment and its variation rate are calculated. It is found that: for electron-doped Mg1-xAlxCNi3(0≤x≤0.5), the superconductivity and magnetic fluctuations decrease gradually with increasing doping. For hole-doped Mg1-xNaxCNi3 with x=0.12, a ferromagnetic phase transition occurs and superconductivity disappears. In the hole doping range of 0≤x<0.12, there is the unstable superconducting state with spin fluctuations.
The division of iron's core and valence states under high pressures via first-principles calculation
Authors: Sun Bo  , Liu Shao-Jun  , Zhu Wen-Jun  ,   (1)北京师范大学物理系，北京  100875; (2)中国工程物理研究院流体物理研究所，绵阳  621900
Published: December 2020

We performed first-principles calculation for the body-centered cubic iron based on density-function theory, employing the pseudopotentionals and plane-wave method. We set the computational precision of the energy of one atom to 0.01 eV and make the spin-polarized total-energy calculation. The calculated results show that the 3p state should be treated as valence state when pressure is higher than 140 GPa, while the contribution to the total energy due to the dispersion of 3s state can be ignored for the whole range of earth's core condition.
The dc Josephson current in superconductor-ferromagnet/insulator/spin-triplet p-wave superconductor junctions
Authors: Li Xiao-Wei  ,   淮阴师范学院物理系，淮安  223001
Published: December 2020

From the Bogoliubov-de Gennes equations, we obtain the self-consistent equation for a ferromagnetic superconductor. Using the Furusaki-Tsukada formula, we calculate the dc Josephson current in superconductor-ferromagnet/insulator/spin-triplet p-wave superconductor (FS/I/p) junctions. It is found that the dc Josephson currents in FS/I/p are suppressed by the presence of exchange field and insulating barrier scattering. The period of oscillation curves of the Josephson current is π when there exist px-wave symmetries for the pairing symmetries of spin-triplet superconductor.
Kondo interactions in the CeOs4Sb12 skutterudite studied by inelastic neutron scattering
Authors: Yang Chang-Ping  , Zhou Zhi-Hui  , Wang Hao  , K. Iwasa  , M. Kohgi  ,   (1)湖北大学物理学与电子技术学院，武汉  430062; (2)湖北大学物理学与电子技术学院，武汉  430062;日本东北大学物理系，日本仙台  981-0935; (3)日本东北大学物理系，日本仙台  981-0935
Published: December 2020

The energy gap near Fermi surface due to the hybridization of Ce3+ 4f1 and conduction electrons is the key to understand the physical properties of the CeOs4Sb12 compound, such as Kondo insulating behavior, moment quench of Ce3+ at low temperatures and the characteristics of heavy fermion. In this work, inelastic neutron scattering spectra of powder CeOs4Sb12 sample were collected at different temperatures using LAM-D neutron spectrometer at KEK pulsed neutron source. The result indicates that the CeOs4Sb12 skutterudite is a Kondo insulator with a c-f interaction of 3.1 meV. The Debye temperature is determined as 317 K.
Room-temperature ferromagnetism in Co-doped ZnO diluted magnetic semiconductor
Authors: Wang Yi  , Sun Lei  , Han De-Dong  , Liu Li-Feng  , Kang Jin-Feng  , Liu Xiao-Yan  , Zhang Xing  , Han Ru-Qi  ,   北京大学微电子学研究所，北京  100871
Published: December 2020

The room-temperature ferromagnetism (RTFM) of Co-doped zinc oxide are reported in this paper. The Zn1-xCoxO (x=0.02, 0.06, 0.10) specimens were synthesized by solid state reaction of the mixture of ZnO and Co2O3 powders. The specimens were then annealed in the hydrogenation ambience. The RTFM was found in the hydrogenated samples, and the hysteresis loops of the hydrogenated Co-doped ZnO samples were measured at 300 K by using the superconducting quantum interference device magnetometer. The samples were further measured by X-ray diffraction, X-ray photoelectron spectroscopy, and high-resolution transmission electron microscopy.
Self-similarity of the electro-optical effects
Authors: Tong Yong-Zai  , Wang Xi-An  , Yu Ben-Hai  , Hu Xue-Hui  ,   (1)信阳师范学院物理电子工程学院，信阳  464000; (2)中国科学院物理化学技术研究所，北京  100080
Published: December 2020

Based on the electro-optical coefficients, the Miller-δ coefficients of KNbO3, LiNbO3, BaTiO3 and several semiconductor crystals were calculated. The results show that the coefficients are frequency independent and are the same for unclamped and clamped values, so it is feasible to take the Miller-δ coefficients to characterize the nonlinear optical properties. Furthermore, a novel mechanism of the electro-optical effects is presented which maintains that the electro-optical effect results from the self-similarity of the nonlinear system, manifested as the recopy of the linear properties and the Miller-δ coefficients are the proportion factors of self-copy.
Small angle X-ray scattering research of the relaxation and crystallization process in Cu60Zr30Ti10 amorphous alloy
Authors: Cheng Wei-Dong  , Sun Min-Hua  , Li Jia-Yun  , Wang Ai-Ping  , Sun Yong-Li  , Liu Fang  , Liu Xiong-Jun  ,   (1)北京科技大学新金属材料国家重点实验室，北京  100083; (2)哈尔滨师范大学物理系，哈尔滨  150025
Published: December 2020

Small angle X-ray scattering technique was used to investigate the evolution of microstructure in Cu60Zr30Ti10 amorphous alloy heated at temperatures from 300 to 813 K. It is confirmed that the Cu-rich domains in the diameter range about 30 nm exist in the as-quenched state. The structural relaxation can be divided into the low temperature structure relaxation in the temperature range from 300 to 573 K and the high temperature structure relaxation in the temperature range from 573 K to the temperature of glass transition. The Cu-rich domains with ordered clusters are the basis of crystallization. Porod curves indicate that there is a sharp boundary between the nano body-centred-cubic CuZr precipitates and the matrix.
Investigation on the crystal structure, optical and electrical properties of Er3+ implanted CdTe thin film
Authors: Hou Juan  , Zheng Yu-Feng  , Dong You-Zhong  , Kuang Dai-Hong  , Sun Yan-Fei  , Li Qiang  ,   新疆大学物理科学与技术学院，乌鲁木齐  830046
Published: December 2020

The structure, optical and electrical properties of the CdTe polycrystalline thin film prepared by close-space sublimation and doped with rare earth element erbium using ion implantation had been investigated by means of X-ray diffraction, scanning electron microscopy, ultraviolet visible spectroscopy, Hall effect and impedance measurement. The results indicate that the crystallinity of the samples can be improved with suitable doping concentration. It is believed that the grain-boundary barrier of the thin film CdTe:Er can be decreased due to the appearance of electron traps at grain boundaries. It is found that the implantation of Er3+ in CdTe thin film causes a great change in conductivity but only a little influence on optical energy band gap of the samples.
The new algorithm for standalone positioning with global positioning system and numerical experiments
Authors: Huang Si-Xun  , Sheng Zheng  ,   解放军理工大学气象学院，南京  211101
Published: December 2020

To determine the approximate position of a global positioning system receiver, the Bancroft method can provide the initial value for linearization of the observation equation, which can then be solved by the least-square (LS) method. Because the solution of LS method is not unique and the observation data have noise, the solution is ill-posed. In order to solve the problem, we introduce the regularization method combined with the optimum choice of regularization parameter. The experimental result indicates that it can enhance the resistance to bad errors, which has significance in real-time fast positioning.
Scale-free networks with the power-law exponent between 1 and 3
Authors: Guo Jin-Li  , Wang Li-Na  ,   (1)上海理工大学管理学院，上海 200093; (2)上海理工大学管理学院，上海 200093;内蒙古工业大学理学院，呼和浩特 010051
Published: December 2020

Basing on the batch arrival concept in the queue theory, this paper proposes a Poisson network model with node batch arrival. The Nodes arrive the system as a Poisson process with rate λ. In the first model, the batch is a power function of the batch number with exponent θ(0≤θ<+∞). Using Poisson process theory and continuum approach, we found that the stationary mean degree distribution of this model is a power-law distribution, and its power-law exponent is between 1 and 3. In the second model, the batch is a log function of the batch number and we obtained that the power-law exponent of stationary mean degree distribution is 3 when the batch rises more slowly. So our model is not only the extension of the BA model, but also a theoretical foundation of many real networks of which the power-law exponent is between 1 and 2.
Output time-delay feedback control of chaos in the voltage-mode BUCK converter
Authors: Lu Wei-Guo  , Zhou Luo-Wei  , Luo Quan-Ming  ,   重庆大学电气工程学院高电压与电工新技术教育部重点实验室，重庆 400030
Published: December 2020

To realize the control of chaos in the voltage-mode BUCK converter, the output time-delayed feedback control (TDFC) is introduced into its control prototype. Based on the quantified analyses in the frequency domain, harmonic balance method is used to ascertain the regulating range of feedback control gain and delay time. Meanwhile the TDFC is equivalent to a kind of simple passive feedback control when the delay time is much smaller than the switch period. And the simulation results of these two methods are considered the same. In the end the experimental circuit of the voltage-mode BUCK converter with passive feedback control is set up. By this means the chaos state of BUCK converter can be quickly controlled into period state and the ripple of voltage and current will be decreased.
Adaptive tracking control of the Chen system
Authors: Chen Long  , Wang De-Shi  ,   海军工程大学兵器工程系,武汉 430033
Published: December 2020

The tracking control of chaotic Chen system is realized using a nonlinear single-input controller. According to the structure characteristic of the Chen system, proper feedback form is selected and an adaptive single-input controller is designed, which makes the Chen system track a certain variable of the Rossler system with unknown parameters. The Lyapunov direct method is applied to prove that the error signal asymptotically approaches zero. Numerical simulations show that the proposed control method is feasible, and the identification of unknown parameters can be realized.
Theoretical research on radiative transition probabilities of 2p4f—2p3d for NⅡ
Authors: Shen Xiao-Zhi  , Yuan Ping  , Li Ji-Guang  , Dong Chen-Zhong  , Xie Lu-You  , Shi Ying-Long  ,   (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；中国科学院寒区旱区环境与工程研究所,兰州 730000
Published: December 2020

On the basis of full relativistic theory, transition probabilities of 2p4f—2p3d for NⅡ have been calculated using multi-configuration Dirac-Fock method. The results are well consistent with experimental value. In the present work, the influence of relativistic effects, electron correlation, relaxation effects, Breit interaction and quantum electrodynamic effects on fine structure and transition probabilities are investigated in detail. The results show that the relativistic effects, electron correlation and relaxation effects are important to the calculations of energy structure and transition probabilities.
Propagation of linearly polarized Gaussian beams through a bar relief diffraction grating
Authors: Li Jian-Long  , Lü Bai-Da  ,   四川大学激光物理与化学研究所，成都 610064
Published: December 2020

Based on the angular spectrum representation and strict modal theory, the propagation of linearly polarized Gaussian beams through a bar relief diffraction grating whose characteristic size is comparable with the wavelength, and the influence of errors of grating structure parameters on the maximum intensity in the relief layer are studied. It is shown that the propagation behavior of beams in each layer is different. The intensity in the relief part is higher than that in the unfilled part. The influence of errors of the grating period on the maximum intensity in the relief layer is dominant. By using the simulated anneal algorithm, system parameters are optimized to control the output beam intensity profile.
Semiclassical theory of optically pumped D2O gas tera-Hz laser
Authors: He Zhi-Hong  , Yao Jian-Quan  , Shi Hua-Feng  , Huang Xiao  , Luo Xi-Zhang  , Jiang Shao-Ji  , Wang Peng  ,   (1)天津大学精密仪器与光电子工程学院激光与光电子研究所，教育部光电信息技术科学重点实验室，天津 300072; (2)天津大学精密仪器与光电子工程学院激光与光电子研究所，教育部光电信息技术科学重点实验室，天津 300072；中山大学光电材料与技术国家重点实验室，广州 510275; (3)中山大学光电材料与技术国家重点实验室，广州 510275
Published: December 2020

By solving the density matrix equation of three-level molecular system, the pulsed laser pumped D2O gas terahertz laser was theoretically studied, the expression of terahertz signal gain coefficient(Gs)and the pumping signal absorption coefficient (Gp) were obtained, the output power density of terahertz laser was calculated numerically by iteration method. The calculation shows that the spectral characteristics of terahertz laser was in full accordance with the stimulated Raman emission. The signal frequency detuning obviously affects the amplification process, and there exists splitting in the curve because of the dipole of D2O gas molecule being disturbed by the field of pumping pulse. The theoretical spectrum is in good agreement with reported experimental results.
Analytical self-similar solutions of Ginzburg-Landau equation for the dispersion decreasing fiber
Authors: Feng Jie  , Xu Wen-Chen  , Li Shu-Xian  , Chen Wei-Cheng  , Song Fang  , Shen Min-Chang  , Liu Song-Hao  ,   (1)光子信息技术广东省高校重点实验室，华南师范大学光电子信息科技学院，广州 510006; (2)华南师范大学物理与电信工程学院，广州 510006
Published: December 2020

Using the method based on the technique of symmetry reduction, we find the general analytical parabolic asymptotic self-similar solutions for the varying coefficient of Ginzburg-Landau equation that take consideration of the influence of the doped fiber retarding time. The parabolic asymptotic amplitude function, change of strict linear phase chirp and the effective temporal pulse width of self-similar pulse with gain dispersion are given for the dispersion decreasing fibers with longitudinal exponential distribution and hyperbolic distribution. And these theoretical results have been confirmed by numerical simulation in this paper.
Theoretical study of molecular vibrational hyperpolarizability of 4-N-methylstilbazonium salt derivatives
Authors: Lu Zhen-Ping  , Han Kui  , Li Hai-Peng  , Zhang Wen-Tao  , Huang Zhi-Min  , Shen Xiao-Peng  , Zhang Zhao-Hui  , Bai Lei  ,   中国矿业大学理学院物理系，徐州 221008
Published: December 2020

Based on double harmonic oscillator (DHO) approximation, the static vibrational first hyperpolarizabilities,and the IR and Raman spectra of 4-N-methylstilbazonium salt derivatives are calculated using coupled perturbed Hartree-Fock (CPHF) approach. Two vibrational normal modes which dominate the contribution to the vibrational first hyperpolarizabilities are obtained. It is found that the static vibrational first hyperpolarizabilities of title molecules are large and show a good linear relationship with their electronic counterparts. For the first time we give an approach of estimating the vibrational first hyperpolarizabilities using a few normal modes identified from IR and Raman spectral peaks, which the name as the few mode approach. The results indicate that this approach is practical in the estimation of the vibrational first hyperpolarizability.
Tunable parametric fluorescence using a single crystal
Authors: Hou Mi-Na  , Liu Hong-Jun  , Zhao Wei  , Wang Yi-Shan  ,   (1)中国科学院西安光学精密机械研究所，瞬态光学与光子技术国家重点实验室，西安 710119; (2)中国科学院西安光学精密机械研究所，瞬态光学与光子技术国家重点实验室，西安 710119；中国科学院研究生院，北京 100039
Published: December 2020

In this paper, we investigate the mechanism of tunable parametric superfluorescence(PS) based on the second harmonic generation and parametric processes taking place in the same nonlinear crystal(BBO). The tunable spectra of PS has been generated between 480 nm and 530 nm, which is pumped by the second-harmonic from the high-power Ti:sapphire laser system at 1 kHz repetition rate. We present the generation mechanism of PS theoretically and simulate the process of PS ring using the amplification transfer function. The experiment and the theory show that PS will appear when the phase matching angle for second-harmonic generation is close to the optimal pump angle for optical parametric generation, and then the tunable spectra of PS are generated by slightly adjusting the crystal angle. The result provides a theoretical basis for controlling the generation of PS and quantum entanglement states, which is of great significance for the development of quantum imaging, quantum communications and other applieations.
Band structures and electric fields of one-dimensional photonic crystals composed of alternate layers of left-handed and right-handed materials
Authors: Wang Tong-Biao  , Liu Nian-Hua  ,   南昌大学高等研究院,南昌 330031
Published: December 2020

We theoretically studied the band gap structure of one-dimensional photonic crystals constituted by alternate layers of left-handed and right-handed materials, and found that the band gap structure is different from the usual photonic crystals. With an appropriate choice of the parameters, we show that it is possible to realize an absolute band gap for either TE or TM polarization of the electromagnetic waves, which can not be found in normal photonic crystals. The wave function of electric field in the pass band is strongly localized compared with the normal photonic crystals. And we give an example in which we substitute the left-handed materials with dispersion materials, and get different energy bands in different areas.
Collision process of two shockwaves
Authors: Zhang Yi  , Zheng Zhi-Yuan  , Li Yu-Tong  , Liu Feng  , Li Han-Ming  , Lu Xin  , Zhang Jie  ,   (1)中国科学院物理研究所北京凝聚态物理国家实验室,北京 100080; (2)中国科学院物理研究所北京凝聚态物理国家实验室,北京 100080；中国地质大学材料科学与工程学院，北京 100080; (3)中国科学院物理研究所北京凝聚态物理国家实验室,北京 100080；中国矿业大学，北京 100083
Published: December 2020

The collision of the two shockwaves induced by laser confined ablation is investigated by time-resolved shadowgraph. Through the observation of the temporal and spacial evolution of the two shockwaves, it is found that the shockwaves do not interact with each other but interact with the plasma induce by ablation in the collision.
Growth of well-aligned carbon nanotubes arrays by chemical vapor deposition
Authors: Han Dao-Li  , Zhao Yuan-Li  , Zhao Hai-Bo  , Song Tian-Fu  , Liang Er-Jun  ,   郑州大学物理工程学院,材料物理教育部重点实验室,郑州 450052
Published: December 2020

A non-template CVD method was used to synthesize well-aligned carbon nanotube (ACNT) arrays. Ferrocene was used as a catalyst, xylene as the carbon source. This process carried out in a single-furnace system. The products were characterized by Scanning Electron Microscopy(SEM), Transmission Electron Microscopy(TEM), Energy Dispersive Spectrometry(EDS) and Raman Spectroscopy. The effects of process parameters on ACNT arrays growth were also investigated. The results show that well-aligned carbon nanotubes can be easily grown on polished silicon substrate at 800℃ with catalyst concentration of 0.02mg/L. Under the above conditions the rate of growth of ACNT arrays can reach 25μm/min.
The complete solution of zero-state response in mesoscopic LC circuit
Authors: Zhou Xiao-Fang  ,   漳州师范学院物理与电子信息工程系，漳州 363000
Published: December 2020

The exact solution of time evolution operator was obtained by applying the gauge transform of algebra dynamic. Such an operator describes the quantum state of time dependence of mesoscopic LC circuit containing voltage source. The zero-state response in mesoscopic LC circuit was researched, and the charge and current zero-state response of the import signal were also acquired. The result showed that the system of mesoscopic LC circuit has linear time invariant feature, and the response in mesoscopic LC circuit is the same as in the macroscopic LC circuit.