bluuebunny/crossref_metadata_2025 huggingface dataset:
Preparation and luminescence characteristics of SrAl2B2O7:Dy3+ phosphor
Authors: Yang Zhi-Ping  , Ma Xin  , Zhao Pan-Pan  , Song Zhao-Feng  ,   College of Physics Science and Technology, Hebei University, Baoding 071002, China
Published: December 2020

The SrAl2B2O7:Dy3+ phosphor is synthesizd through a general high temperature solid-state reaction, and its luminescence properties are investigated. The emission spectrum of SrAl2B2O7:Dy3+ shows the bands at 480nm,573nm and 678nm under the 365nm excitation, corresponding to the 4F9/2→6H15/2,4F9/2→6H13/2 and 4F9/2→6H11/2 typical transitions of Dy3+ respectively. The excitation spectrum for 573nm emission has excitation bands at 295 nm,325 nm,350 nm,365 nm and 400nm. The influence of doped Dy3+ contentration on the emission spectrum and the luminescent intensity of SrAl2B2O7:Dy3+ is investigated. The result shows that the intensity ratio of yellow emission (573nm) to blue emission (483 nm), Iy/Ib, increases with the increase of Dy3+ concentration, which may be explained by the Judd-Ofelt theory. The luminescent intensity increases first with the increase of Dy3+ concentration, then decreases. The concentration self-quenching is attributed to the d-d interaction according to the Dexter theory. The introducing of charge compensation agents of Li+, Na+ and K+ ions can augment the emission intensity. It is found that Li+ ions are the best to enhance the emission intensity.
Study of the retrieval algorithm of emission gas spatio-temporal distribution of pollution source using the infrared solar occultation flux (SOF) method
Authors: Liu Zhi-Ming  , Liu Wen-Qing  , Gao Min-Guang  , Tong Jing-Jing  , Zhang Tian-Shu  , Xu Liang  , Wei Xiu-Li  , Jin Ling  , Wang Ya-Ping  , Chen Jun  ,   Key Laboratory of Environmental Optics and Technology, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Science, Hefei 230031, China
Published: December 2020

Method of solar occultation flux infrared spectroscopy to detect the pollution emission flux of sources is presented in detail. It is developed based on the FTIR technique. A Two-layer radiative transfer model is established theoretically. Algorithm of transmissivity calculation of pollution gas is expatiated. The method to obtain the absorption coefficient of molecules from HITRAN, NIST and QAsoft databases is mentioned. Levenberg-Marquardt algorithm is used to calculate column concentration of pollution gas from pollution source. The distribution of column concentration is drawn by software developed by our group. The total system and the sun tracker are shown in the paper. The distribution of column concentration of NH3 is measured in a chemical plant in Hefei China. The calculated distribution of column concentration of NH3 is consistent with the measured one in the chemical plant.
Theoretical calculation of the low-energy scattering cross sections for He-Li2 system
Authors: Linghu Rong-Feng  , Li Jin  , Si Guan-Jie  , Yang Xiang-Dong  ,   Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, China;,   Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, China; School of Material and Chemical Engineering, Hainan University; Hainan Provincial Key Laboratory of Research on Utilization of Si-Zr-Ti Resources , Haikou 570228, China;,   Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, China; School of Physics and Electronic Science, Guizhou Normal University, Guiyang 550001, China
Published: December 2020

In this paper, the Fuchs potential model and the Close-coupling method are used to calculate the low-energy cross sections for a He-Li2 scattering system. The dependences of total cross section on energies, differential section on angles, and partial wave cross section on quantum number of total angular momentum are discussed . The quantum effect on energy obtained.
Coherent beam combining of multi-wavelength lasers based on stochastic parallel gradient descent algorithm
Authors: Wang Xiao-Lin  , Zhou Pu  , Ma Yan-Xing  , Ma Hao-Tong  , Xu Xiao-Jun  , Liu Ze-Jin  , Zhao Yi-Jun  ,   College of Optoelectronic Science and Engineering, National University of Defense Technology, Changsha 410073, China
Published: December 2020

Owing to the restriction of the stimulated Brillouin scattering (SBS) and other nonlinear effects, the output power of the single frequency amplifier is ar a level of about hundred watts. Multi-wavelength and non-single frequency seed laser will mitigate the SBS and improve the output power of the fiber laser amplifier. The coherent beam combining of the non-single frequency and/or multi-wavelength laser will greatly increase the total output power of the coherent beam combining as compared with the coherent beam combining of a single frequency laser. Based on the stochastic parallel gradient descent (SPGD) algorithm, coherent combining of four channel four-wavelength lasers is realized. In the close loop state, the mean power of the main-lobe is four times higher than that of the open-loop, approaching 75% of its ideal value. The coherent combining of the multi-wavelength and non-single frequency laser is demonstrated and an approach to the high power coherent beam combining is provided.
Bidirectional chaos communication based on semiconductor laser with incoherent optical feedback
Authors: Cao liang-Ping  , Xia Guang-Qiong  , Deng Tao  , Lin Xiao-Dong  , Wu Zheng-Mao  ,   (1)School of Physics, Southwest University, Chongqing 400715, China; (2)School of Physics, Southwest University, Chongqing 400715, China; Elementary Education College, Chongqing Normal University, Chongqing 400700, China
Published: December 2020

In this paper, a bidirectional chaos communication system based on semiconductor lasers with incoherent optical feedback is presented, and the synchronization characteristics and the communication performances of such a system are numerically investigated. The results show that when the parameters of the two lasers are matched, the good-quality chaos synchronization with zero lag time and simultaneously bidirectional message transmission can be realized and when the parameters of the two lasers are mismateched, the synchronization quality and communication performance are affected to a certain extent, but this system possesses good robustness against mismatched parameters and can still realize bidirectional chaos communication within a certain mismatched parameter range.
A new type of THz photonic crystal fiber with super-flattened dispersion
Authors: Jiang Yue-Jin  , Shi Wei-Hua  , Li Pei-Li  , Zhao Yan  ,   Institute of Optical Communication, Nanjing University of Posts and Telecommunications, Nanjing 210003, China
Published: December 2020

A new type of THz photonic crystal fiber with super-flattened dispersion and air hole varying cladding is designed in this paper. Its dispersion properties are analyzed by using the finite-difference time-domain (FDTD) method. The results show that the new THz photonic crystal fiber is better than THz photonic crystal fiber with air hole unarying cladding in controlling the dispersion, and that the new THz photonic crystal fiber has the flattened dispersion when the third ring diameter has the same value as the forth ring diameter. When the air hole diameters are d1=0.85d4, d2=0.95d4,d3=d4(d1,d2,d3,d4 are the diameters of air hole from the inter clad to the outer clad), the new THz photonic crystal fiber can have almost super-flattened dispersion at a level of -0.1±0.3 ps/(nm·km), a good ability to restrict the THz wave and a low loss in a wavelength reange between 60 μm and 65 μm.
An extended model for ion charge state distribution of plasmas in collisional radiative steady state
Authors: Duan Yao-Yong  , Guo Yong-Hui  , Qiu Ai-Ci  , Wu Gang  ,   Northwest Institute of Nuclear Technology, Xi'an 710024, China
Published: December 2020

A non-Boltzmann distribution is constructed in terms of ion excitation-deexcitation equilibrium in plasmas, over which the rate coefficients of atomic processes are averaged, and an extended numerical model for charge state distribution of plasmas in collisional radiative steady state is established. The model is used to compute mean ion charge for various plasmas, ranging from low Z to high Z elements, as a function of electron temperature and density. Furthermore, the effects of non-Boltzmann distribution on mean ion charge and ion excited configuration population are investigated. The results show that the ion excited configuration population is evidently affected by the non-Boltzmann distribution.
Experimental study of shock waves induced by high-power pulsed laser in AZ31B magnesium alloy
Authors: Zhang Yong-Kang  , Yu Shui-Sheng  , Yao Hong-Bing  , Wang Fei  , Ren Ai-Guo  , Pei Xu  ,   School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013, China
Published: December 2020

In order to study the attenuation of shock waves induced by a high-power pulsed laser in magnesium alloy, an AZ31B magnesium alloy sample is processed with an Nd:Glass laser with a wavelength of 1054 nm and pulse width of 23 ns, and the relative pressures of the shock waves are measured on time by a polyvinglidene fluoride (PVDF) gauge with a short rise time and a wide linear response range, combined together with an oscilloscope. The law of attenuation of laser shock wave is obtained by measuring the intensity pressures on the rear surface of the target for different thicknesses through which the shock waves pass each time. The experimental results show that the average velocity of the shock wave attenuation in magnesium alloy is 5.83×103 m/s with using a laser pulsed energy of 5 J is in good agreement with the propagation velocity of stress longitudinal wave; the law of the shock wave attenuation is exponential. The experimental result can be very useful for the laser shock processing on magnesium alloy.
Discharge characteristics of confined cathode micro-arc oxidation
Authors: Zhang Xin-Meng  , Tian Xiu-Bo  , Gong Chun-Zhi  , Yang Shi-Qin  ,   State Key Laboratory of Advanced Welding Production and Technology, Harbin Institute of Technology, Harbin 150001, China
Published: December 2020

Confined cathode micro-arc oxidation (CCMAO) has been investigated in Na2SiO3-KOH solution with industrial pure aluminum as substrate materials. The effects of the electrode distance (ED) on working current, potential distribution, arcing voltage and so on have been focused on. The energy efficiency as a function of ED has also been evaluated. The results show the working current decreases with increasing ED for the same exposure area of confined cathode and anode. However, the working current increases with increasing ED with only the cathode confined. It is attributed to different electrical field on the anode surface. With increasing ED, the electrical field beneath the confined cathode decreases while that far from the cathode increases. This leads to a different total working current. The arcing voltage increases with increasing ED while the effective voltage on anode surface nearly keeps constant. The thickness of the ceramic coating produced at a small ED is much higher than that at a larger ED. The energy consumption per unit volume of oxides by CCMAO indicates that smaller ED leads to higher energy efficiency.
First-principles investigation of carrier Auger lifetime and impact ionization rate in narrow-gap superlattices
Authors: Sun Wei-Feng  , Li Mei-Cheng  , Zhao Lian-Cheng  ,   Department of Information Material Science and Technology, School of Material Science and Engineering,Harbin Institute of Technology, Harbin 150001, PR China
Published: December 2020

We investigate theoretically the technologically essential Auger recombination lifetime in narrow-gap semiconductor superlattices by means of a completely first-principles formalism, based on accurate energy bands and wave functions provided by the full-potential linearized augmented plane wave scheme. The minority carrier Auger lifetimes are determined by two correlated approaches: (1) direct evaluation in Fermi's golden rule, and (2) indirect evaluation, based on a detailed balance formulation relating Auger recombination and its inverse process, impact ionization, in a unified framework. Lifetimes determined by the direct and indirect methods for n -doped HgTe/CdTe and InAs/InxGa1－xSb superlattices exhibit excellent consistency with experimentally measured values. This justifies the computational formalism as a new sensitive tool in performance optimization of the synthetic narrow-gap semiconductor superlattice systems.
Study of the structure evolution and ground state energy of ConCu55－n(n=0—55) bimetallic clusters by using the Gupta potential combined with a genetic algorithm
Authors: E Xiao-Liang  , Duan Hai-Ming  ,   College of Physical Science and Technology, Xinjiang University, Urumqi 830046, China
Published: December 2020

The ground-state structures and energies of the bimetallic clusters ConCu55－n(n=0—55) were obtained by using the semi-empirical Gupta potential combined with a genetic algorithm. The ground-state geometries of those bimetallic clusters can be characterized by the basic Mackay icosahedron of the pure Co55 (Cu55) cluster. Beginning with n=0 (Cu55), the Cu atom(s) is(are) replaced in order and continuously by the Co atom(s) from the center to the surface and from the edge to the vertex. The ground-state structure depends on the number of the Co—Co bonds which have the largest energy, the number of the Co-Cu bonds with large energy and the average bond length of those bonds. Co13Cu42 is a magic cluster with an icosahedral core formed by 13 Co atoms, which plays a key role in the high stability of those bimetallic clusters.
Molecular dynamical simulation on the mechanical property of hydrogenated diamond-like carbon films
Authors: Quan Wei-Long  , Li Hong-Xuan  , Ji Li  , Zhao Fei  , Du Wen  , Zhou Hui-Di  , Chen Jian-Min  ,   (1)State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China; (2)State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China; School of Mathematics, Physics and Software Engineering, Lanzhou Jiaotong University, Lanzhou 730070, China
Published: December 2020

The mechanical property of diamond-like carbon films with different hydrogen concentration is studied using molecular dynamical simulation based on REBO potential energy functions. The stiffness, hardness, and elastic modulus of the films are calculated from the load-unload curve. It is shown that both of the fraction of sp3 carbon and the concentration of H in the films have strong influence on the film hardness. When H concentration in the film is lower than 39%, the hardness is mainly determined by sp3 carbon, when H concentration further increases, the hardness decreases greatly despite the increase of the sp3 fraction.
Study on mechanism of current collapse and knee voltage drift for AlGaN/GaN HEMTs
Authors: Wang Lin  , Hu Wei-Da  , Chen Xiao-Shuang  , Lu Wei  ,   National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Science, Shanghai 200083, China
Published: December 2020

In this article, we comprehensively showed the impact of barrier layer traps, buffer layer traps and surface charge on current collapse and knee voltage change, pointed out that the change in the concentration of surface charge and barrier layer traps have little influence on the 2DEG density in the channel.When the concentration of surface charge changes, the knee voltage drift and strength of current collapse are in close connection with the change of potential energy in quantum well.Buffer layer has stronger local effect than barrier layer, when the concentration of bulk traps change in these layers, knee voltage drift is mainly caused by the change of 2DEG density, but has less change compared with the situation of surface charge.Potential energy changes in the quantum well is an important reason for the change of knee voltage, the strength of current collapse is determined by the size of potential energy and 2DEG density.
Influence of particle plasmon resonance on the photoluminescence of exciplex in organic semiconductor blend film
Authors: Peng Chun-Zeng  , Zhang Xin-Ping  , Liu Hong-Mei  , Feng Sheng-Fei  ,   College of Applied Sciences,Beijing University of Technology,Beijing 100124,China
Published: December 2020

We investigate in this paper the influence of the localized plasmon resonance of gold nano-island structure on the photoluminescence of the exciplex in the polymer blends. The experimental results show that when the particle plasmon resonance overlaps the photoluminescence spectrum of the exciplex,the corresponding emission intensity is enhanced significantly. Furthermore, alonger lifetime is observed with the exciplex emission. We propose that the localized electrical field induced by the particle plasmon resonance increaseds the exciton diffusion length and thus conduces to the formation of the exciplex in the phase separation interface.
2.9 μm luminescence properties of Pr3+/Ho3+ codoped Ge-Ga-Se glasses
Authors: Zhu Jun  , Dai Shi-Xun  , Wang Xun-Si  , Shen Xiang  , Xu Tie-Feng  , Nie Qiu-Hua  ,   College of Information Science and Engineering,Ningbo University,Ningbo 315211,China
Published: December 2020

A series of chalcogenide glasses based on Ge25Ga10Se65 system co-doped with Ho3+/Pr3+ ions of different ratios were synthesized by melt-quenching technique. The absorption spectra,mid-infrared fluorescence and lifetime of glass samples under 908 nm laser excitation were measured. The emission cross section of Ho3+:5I7→5I8 and absorption cross section of Pr3+:3H4→3F2 were calculated. The energy transfer efficiency between Ho3+ and Pr3+ ions with different Pr3+ ion concentrations have been discussed. Through fitting the 2.0 μm fluorescence decay curves of Ho3+ ions,the energy transfer regime was judged. The results prove thatTm3+ is an efficient sensitizer which enhances the Ho3+: 2.9 μm fluorescence intensity significantly.
Magnetoconductance in Alq3-based organic light-emitting diodes
Authors: Zhang Yong  , Liu Rong  , Lei Yan-Lian  , Chen Ping  , Zhang Qiao-Ming  , Xiong Zu-Hong  ,   MOE Key Laboratory on Luminescence and Real-Time Analysis,School of Physical Science and Technology,Southwest University,Chongqing 400715,China
Published: December 2020

Organic light-emitting diode (OLED) with structure of ITO/CuPc/NPB/Alq3/LiF/Al was fabricated,and the magnetic field effect on the injection current (magnetoconductance or MC effect) at 300 K,260 K,220 K,and 180 K were measured at constant voltage bias. During the transition of injection current from bipolar current to unipolar current,the MC of the device increased firstly and fell with the decreasing current. The MC became smaller at the lower temperatures. However,under all measurement conditions,the values of the MC were always positive. The inversion of MC from positive to negative as reported in literatures was not observed. The experimental results demonstrate that the ±MC effects in OLED not only depend on the unipolar or bipolar current. It is also related with the organic materials and device structure. Using the magnetic field modulated electron-hole pair mechanism and bipolaron model,the positive MC effects in bipolar and unipolar injection current are interpreted, respectively.
Fabrication and luminescence properties of Si quantum dots based on Si-rich SiNx/N-rich SiNy multilayer
Authors: Huang Rui  , Wang Dan-Qing  , Song Jie  , Ding Hong-Lin  , Wang Xiang  , Guo Yan-Qing  , Chen Kun-Ji  , Xu Jun  , Li Wei  , Ma Zhong-Yuan  ,   (1)Department of Physics and Electrical Engineering, Hanshan Normal University, Chaozhou 521041, China; (2)State Key Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China
Published: December 2020

SiN-based multilayers were prepared in a plasma enhanced chemical vapor deposition system followed by subsequently thermal annealing and laser irradiation with the aim of fabrication three-dimensional constrained, size-controlled and well-regulated Si nanocrystals. The experimental results show that Si nanocrystals grow in the Si-rich SiN sublayer. Furthermore, the grain size can be controlled according to the thick of Si-rich SiN. It is also found that the crystalline fraction of the multilayers irradiated by laser is significantly higher than that by thermal annealing. The devices that employing the laser-irradiated multilayer as luminescent active layer exhibit an enhanced visible electroluminescence and the external quantum efficiency is improved by 40% in comparison with the device without annealing.
Calculation of positron bulk lifetime of sphalerite crystalloid
Authors: Zhang Jie  , Chen Xiang-Lei  , Hao Ying-Ping  , Ye Bang-Jiao  , Du Huai-Jiang  ,   Department of Modern Physics,University of Science and Technology of China, Hefei 230026, China
Published: December 2020

Here, we calculated theoretically the positron bulk lifetime of cuprous halide (except CuI,which has not the blende structure) and some borides with the method of atomic superposition approximation (ATSUP) on the basis of the theory of local density approximation (LDA) and general gradient approximation (GGA),the calculated results are in good agreement with the experiment. On the other hand, the positron lifetime of many other compounds which have blende structure are calcualted,and the results agree with the results published in literatur. Here we take the CuCl as an example,the pictures of the electron potential energy distribution, probability density of positron and positron annihilation rate are given. Finally the systematic results were fitted with curve as a function of lattice constants, and the fitted results are compared with the outcomes of other articles.
X-ray excited luminescence property of ZnS:Cu, Tm fine particles synthesized by hydrothermal method
Authors: Cao Wang-He  , Xin Mei  ,   (1)College of Science, Dalian Nationalities University, Dalian 116605, China; Optoelectronic Technology Institute, Dalian Maritime University, Dalian 116026, China; (2)Optoelectronic Technology Institute, Dalian Maritime University, Dalian 116026, China
Published: December 2020

The ZnS:Cu,Tm X-ray phosphor fine particles synthesized by hydrothermal method has been reported for first time and its photoluminescence (PL) and X-ray excited luminescence (XEL) properties have been studied in detail also. The direct hydrothermal treatment at 200 ℃ for 12h samples average gain size is about 15 nm; the synthesized spherical-like nanocrystals with well dispersity and narrow gain size distribution show cubic structure. The after annealing in Argon at 900 ℃ for 1h samples agglomerate size is about 200—600 nm and roughly spherical fine particles show pure hexagonal structure. The PL and XEL spectra of all of samples show a broad emission band and an intense emission band in the range of 400—600 nm. The maximum XEL intensity of sample directly synthesized by hydrothermal treatment is observed for Cu/Zn and Tm/Cu are 3×10-4 and 2, respectively. In this condition, the strongest PL and XEL emission is observed for the direct synthesized sample further annealing in Argon at 900℃ for 1h sample and the XEL peak center about 453 nm and 525 nm, respectively. The Samples with highly luminescence efficiencies and the smaller size could enhance the resolution of imaging systems. The difference between PL and XEL spectrum is due to its different excitation mechanism. The luminescence mechanism and different excitation mechanism of PL and XEL have been discussed.
Numerical simulation of the ionization effects of prompt radiation from high-altitude nuclear explosions
Authors: Tao Ying-Long  , Wang Jian-Guo  , Niu Sheng-Li  , Zhu Jin-Hui  , Fan Ru-Yu  ,   (1)Department of Engineering Physics, Tsinghua University, Beijing 100084, China; Northwest Institute of Nuclear Technology, Xi’an 710024, China; (2)Northwest Institute of Nuclear Technology, Xi'an 710024, China
Published: December 2020

In this paper, the Monte Carlo method is used to simulate atmospheric ionization effects of the prompt radiation from high altitude nuclear explosion (HANE). Simulation gives the instantaneous spatial distributions of the electron density in atmosphere. The atmosphere is a kind of non-uniform media, whose density drops rapidly with the increase of height. Therefore, a method, which samples the mass distance to replace the step length of the particle, is used to considerably increase the computing speed. The simulation results show that there is an obvious difference between additional ionization regions of different height of nuclear explosion. As the explosion-height increases, influence range of the prompt nuclear radiation will be wider, but the electron density will be lower.
Interference phase of mass neutrino in Kasner space-time
Authors: Cao Guang-Tao  , Wang Yong-Jiu  ,   Institute of Physics, Hunan Normal University, Changsha 410081, China
Published: December 2020

In Kasner space-time, we calculate the interference phase and oscillation length of the mass neutrinos in some special cases and find that the phase along the null is equivalent to the half phase along the geodesic in the high energy limit. When the parameter a in line element fulfils a=0, the interference phase is the same as that in Schwarzschild space-time. Research on this subject has impact on cosmology.
Estimation of unknown parameters and adaptive anti-synchronization of quadratic autonomous chaos systems via a scale controller
Authors: Liu Di  , Xu Wei  , Guo Pei-Rong  , Ni Fei  ,   Department of Applied Mathematics,Northwestern Polytechnical University,Xian 710072,China
Published: December 2020

Based on Lyapunov stability theory,a simple adaptive scalar controller was designed to realize the anti-synchronization of 3-D quadratic autonomous systems with known or unknown parameters. Furthermore,all the unknown parameters can be estimated dynamically from the time series of the drive and response systems. Numerical simulations show the effectiveness and feasibility of the proposed method.
Simple chaotic oscillator’s chaos behavior and its feedback control circuit design
Authors: Shi Zheng-Ping  ,   College of Mathematics and Computer Science,Fuzhou University,Fuzhou 350108,China
Published: December 2020

The aim of this paper is to study a chaotic oscillators stability and chaos behavior and to determine the conditions for the stability and chaotic behavior of the chaotic oscillator by theoretical analysis. Furthermore,this study also aims to control the chaotic oscillator by an exact feedback linearization method. Finally,both numerical simulations and circuit experiments verify the validity of the theoretical analysis.
The topological variance of neighborhood of a non-hyperbolic fixed point produced by truncation error
Authors: Sheng Li-Yuan  , Zhang Gang  ,   School of Physics Science and Technology,Central South University,Changsha 410083,China
Published: December 2020

In the paper,a direct evidence for truncation error to complicate a simple system is provided,which proves the existence of anti-degradation mechanism in chaotic systems. Both one-dimensional circular arc iterated system and one-dimensional parabola iterated system are constructed,respectively. In each system,there is a non-hyperbolic fixed point. The corresponding iterative sequences are theoretically proved to be simple convergent sequences. However,there are a lot of iterative sequences that could jump over the fixed point in digital experiments. It is clearly revealed by digital-cell analysis that the topological variance of neighborhood of a non-hyperbolic fixed point is produced by truncation error,either a channel of type-I intermittency or a ripple bifurcation is configured from the fixed point.
The evolution of spiral waves in inhomogeneous excitable media
Authors: Dai Yu  , Wei Hai-Ming  , Tang Guo-Ning  ,   College of Physics and Technology,Guangxi Normal University,Guilin 541004,China
Published: December 2020

The effect of small heterogeneous grains with different features and shapes on the evolution of spiral wave is investigated by using the simple model of discrete excitable medium. When the small grains are uniformly distributed in a medium,the instability of spiral wave relates to the shape,density and nature of the grain. The numerical results show that under suitable conditions,the heterogeneous grains can lead to the transition from stable spiral wave to meandering spiral wave in the medium in which it occurs, the spiral wave even drifts out of the boundary of system. The periodic pattern with irregular shape and the periodic maze-type pattern have been observed for the first time. The physical mechanism underlying these phenomena is discussed.
Chaotic synchronization of Chua’s circuits with nonlinear control
Authors: Fu Shi-Hui  , Pei Li-Jun  ,   Department of Mathematics,Zhengzhou University,Zhengzhou 450001,China
Published: December 2020

Chua’s circuits are non-smooth systems. At first,by the generalized Hamiltonian system and observer approach,the problem of the chaotic synchronization of Chua’s circuits with nonlinear control is transformed into that of the stability of zero solution of smooth error systems with nonlinear control. Then,the sliding mode control is applied to the error systems, which stabilizes their zero solutions,and the synchronization conditions are obtained. At last,the numerical results are shown to be in very good agreement with the theoretical analysis.
Study on the phase diagram of the grade roundabout crossing with open boundary condition
Authors: Bai Ke-Zhao  , Kuang Hua  , Liu Mu-Ren  , Kong Ling-Jiang  ,   (1)College of Physics and Technology,Guangxi Normal University,Guilin 541004,China; (2)College of Physics and Technology,Guangxi Normal University,Guilin 541004,China;Shanghai Institute of Applied Mathematics and Mechanics,Shanghai University,Shanghai 200072,China
Published: December 2020

The traffic flow at the roundabout crossing with the inner roundabout lane and the outer roundabout lane is described by a cellular automaton traffic flow model with open boundary condition. Simulation results show that the boundary condition and bottlenecks affect the traffic flow at the roundabout crossing. The enter probability α and the out probability β can change the systemic flux in a certain range. Three phases of the system are differentiated by the relationship between the systemic flux and the enter probability α,the out probability β. The systemic phase diagram is also studied. The research can provide a reference for the realistic traffic control.
Effect of the lane changing probability on the kinetic energy of traffic system
Authors: Shang Hua-Yan  , Huang Hai-Jun  , Tang Tie-Qiao  ,   (1)Institute of Transportation Engineering,Tsinghua University,Beijing 100084,China; (2)School of Economics and Management,Beijing University of Aeronautics and Astronautics,Beijing 100191,China; (3)School of Transportation Science and Engineering,Beijing University of Aeronauticsand Astronautics,Beijing 100191,China;School of Economics and Management,Beijing University of Aeronautics and Astronautics,Beijing 100191,China
Published: December 2020

Based on the properties of the car-following model,we present in this paper a formula of the kinetic energy change and use the formula to study the effect of the lane changing on the kinetic energy of the system. The numerical results show that the lane changing probability and the relative velocity have great effect on the kinetic energy,but the lane changing probability and the relative speed will respectively lessen the frequency and amplitude of the change of the kinetic energy. In addition,the enhanced average kinetic energy of the system will decrease with the increase of its maximum lane changing probability.
Study on queue resource allocation in scale-free networks
Authors: Pu Cun-Lai  , Pei Wen-Jiang  , Miao Rui-Hua  , Zhou Si-Yuan  , Wang Kai  ,   School of Information Science and Engineering,Southeast University,Nanjing 210096,China
Published: December 2020

In this article,information traffic dynamics in scale-free networks with limited queue resource is investigated firstly. It is found that the network transits from a free flow state to full congestion state with the increase in the packet generation rate. Then,a queue resource allocation model based on node degree is proposed. The core of this model is to make the queue length of node i proportional to kβi (ki being the degree of node i and β being an allocation parameter). Simulations show that the capacity of the scale-free network is maximal when β is about 1.25 for the shortest path algorithm used to transfer information. Furthermore,the optimal value of allocation parameter β is irrelevant to the network size and the amount of queue resource.
The evaluation function of weight similarity and its application in community detection in weighted networks
Authors: Shen Yi  , Xu Huan-Liang  ,   College of Information Science and Technology,Nanjing Agricultural University,Nanjing 210095,China
Published: December 2020

An evaluation function of weight similarity in weighted network is proposed,and a spectral algorithm for detecting community structure based on the function is presented. The results show that the algorithm can divide the weighted network into several groups within each of them the edges weights distribute uniformly but at random between them. The algorithm is analyzed by constructing random weighted networks with known community structure. Compared with WEO and WGN,the algorithm has high accuracy when the threshold coefficient takes small values. For a network with n nodes and c communities,the computation complexity of the algorithm is O(cn2/2). By setting different threshold coefficients,a special hierarchical organization which describes the various steady connections between nodes in groups can be discovered by the algorithm. It is different from the conventional concept of community detection in weighted networks which divides the weighted network into several groups in which the edges weights are relatively larger than those in-between them,such that it extracts the information about the structure of weighted networks from another perspective.
The comparison of temporal bond polarizabilities of the nonresonant Raman excited virtual state of ethylene thiourea by two different algorithms
Authors: Chen Yan-Rong  , Wang Pei-Jie  , Fang Yan  ,   Department of Physics, Beijing Key Lab for Nano-photonics and Nano-structure,Capital Normal University, Beijing 100048, China
Published: December 2020

We studied the temporal bond polarizabilities of ethylene thiourea (ETU) from the Raman intensities by two different algorithms. One algorithm includes only the bond stretching modes and the other includes all bond modes. Our analysis shows that, the algorithm using bond stretching modes, in which only the part of Raman peaks whose vibrational modes have relatively larger proportion in the bond stretching are considered, may have larger errors in certain situations where the stretching and bending modes have significant coupling. Otherwise, this algorithm is just suitable, although it may lose certain physical information. The bond polarizabilities provide much information concerning the electronic distribution of nonresonant Raman excited virtual state. At the initial moment of the 514.5 nm excitation, the tendency of the excited electrons is to spread to the molecular periphery. Meanwhile, the relaxation process of the bond polarizability and the characteristic times for these two models are almost the same.
A bottle beam generated by a step refractive index axicon
Authors: Ma Liang  , Wu Feng-Tie  ,   College of Information Science and Engineering, Huaqiao University, Quanzhou, 362021, China
Published: December 2020

Step refractive index axicon for generating bottle beam is proposed for the first time, and the two kinds of models-refractive index step-increase or decrease in radial direction are discussed. The principle of the bottle beam generation is analyzed by geometrical optics. The optical field distribution and 2D light spot image at different propagation distance behind the two kinds of axicons are numerically simulated using the diffraction integral theory. Research result shows that the step-decrease refractive index axicon generates single bottle beam, and the step-increase refractive index axicon generates periodic bottle beams. Bottle beam has a wild application in atom guiding and trapping,optical capture and optical tweezers. Research results in this paper give the significant guidance for the practical applications of the bottle beam.
Study on the tight focusing of the local elliptically polarized beam
Authors: Xu Kai  , Yang Yan-Fang  , He Ying  , Han Xiao-Hong  , Li Chun-Fang  ,   Department of Physics, College of Science, Shanghai University, Shanghai 200444, China
Published: December 2020

When a radially-polarized beam passes through a wave plate, the polarization distribution of the beam strongly depends on the retardation angle and the spatial position. When the retardation angle is changed from 0 to π, the polarization of the beam becomes the local elliptic polarization with non-uniform polarization distribution. The rotating direction of polarization in the first and third quadrants is opposite to that in the second and fourth quadrants. In this paper we have numerically simulated the transverse and longitudinal electric field intensity, the transverse energy flux and the longitudinal angular momentum of the tightly focused beam in the focal plane. Our results show that the sum of the longitudinal angular momentum in the focal plane is zero, but it is varying in different quadrants. The liquid crystal variable retarder (LCVR) is adopted as a real-time continuous tunable wave plate with its retardation angle δ changing from 0 to π by varying the applied voltage. In this case the phase retardation angle δ introduced by the LCVR can be used as a control over the longitudinal electric field intensity and the longitudinal angular momentum.
The data processing method of the temporarily and spatially mixed modulated polarization interference imaging spectrometer
Authors: Jian Xiao-Hua  , Zhang Chun-Min  , Zhu Bao-Hui  , Ren Wen-Yi  ,   School of Science, Xi'an Jiao Tong University, Non-equilibrium Condensed Matter and Quantum Engineering Laboratory, the Key Laboratory of Ministry of Education Xi'an 710049, China
Published: December 2020

A new method of the interferogram formation,recording and processing is proposed for the polarization interference imaging spectrometer. According to the regularities of the optical path difference distribution on the detector, the wide-field-of-view polarization interference imaging spectrometer (WPIIS) is proved to be much suitable for working under temporally and spatially mixed model. In addition, the originally experimental interferogram obtained by WPIIS is processed in this new way, the satisfactory result of interference data and reconstructed spectrum proved that the method is exact and useful.
Correction method for phase-modulation deviation of liquid crystal spatial light modulator in full-color holographic display
Authors: Zheng Hua-Dong  , Yu Ying-Jie  , Dai Lin-Mao  , Wang Tao  ,   Department of Precision Mechanical Engineering, Shanghai University, Shanghai 200072, China
Published: December 2020

It is feasible to realize full-color holographic display based on liquid crystal spatial light modulator by use of multi-wavelength illumination combined with time division multiplexing (TDM) or space division multiplexing (SDM). However, the modulation characteristics of liquid crystal spatial light modulator (LC-SLM) vary with the wavelength of incident laser beam. Especially, the non-linearity and the modulation-depth mismatch of phase modulation curve are the important factors influencing the reconstruction quality of phase hologram in full-color holographic display. In order to solve this problem, a novel method is proposed to correct the gray-scale of phase holograms in the RGB channels with the established gray-mapping model according to the phase modulation curves measured under different wavelengths, and compensate the effects of non-linearity and the modulation-depth mismatch of phase modulation curves. Analysis of numerical and optical reconstruction results are carried out. It is verified that the method is effective to improve the qualities of reconstructed images in the RGB channels.
Theoretical investigation of mode coupling to a microdisk system containing a three-level quantum-dot
Authors: Bai Jiang-Xiang  , Mi Xian-Wu  , Li De-Jun  ,   College of Physics Science and Information Engineering, Jishou University, Jishou 416000, China
Published: December 2020

A full quantum mechanical approach is extended to a coupled waveguide-ring resonator interacting with a three-level quantum dot (QD). The transmission and reflection amplitudes, as well as the resonator and the QD responses, are solved exactly via a real-space approach, which shows the single-photon transport properties. One feature of the system is the coupling between the two degenerate whispering- gallery modes (WGMs) of the resonator at rate β due to backscattering caused by surface roughness of the cavity. Another feature is describing the coupling between QD and the cavity by two parameters g1 and g2. From the analytic numerical results we can see the difference from two-level system.It may better interpret the experiment of a quantum dot strongly coupled to WGMs in a cavity.
Influence of environment temperature wide-range variation on Brillouin shift in optical fiber
Authors: Zhao Li-Juan  ,   National Engineering Laboratory for Biomass Power Generation Equipment, North China Electric Power University, Baoding 071003, China
Published: December 2020

The experiment for measuring Brillouin shift of optical fiber was set up. The Brillouin shift of a dispersion-shifted fiber was experimentally investigated in the range of 20 to 820 ℃, and the data was fitted. When the environment temperature changes in a wide range, the measured data when fitted by a linear relation, will bring about large errors. We set out our study on the basis of the structure and material properties of fused silica, including the thermal expansion coefficient, the density, the refractive index, the Young’s modulus, and the Poisson’s ratio. The mathematical model for the temperature dependence of each of the parameters was built up. Based on the relationships between Brillouin shift and the material properties, the Brillouin shift has been formulated as a second-order polynomial of temperature over a wide temperature range. Compared with our experimental results, the theoretical results are in good agreement, which lays a foundation for the wide-range Brillouin distributed temperature sensor.
Simulation of the temperature-beam coupling in frequency doubling of BBO crystals
Authors: Chang Yan-Qin  , Shen Tao  , Andreev Y. M.  , Shaiduko A. V.  , Huang Jin-Zhe  , Wang Hong  ,   (1)Department of Optical Information Science and Technology, Harbin University of Science and Technology, Harbin 150080, China; (2)俄罗斯科学院西伯利亚分院气候生态系统监测研究所,汤姆斯克 634055
Published: December 2020

First, a frequency doubling model with 4-dimensional temperature-beam coupling was proposed in this paper on the assumption of an infinite transverse crystal section. The frequency doubling process, by using analytical formula and iterative method, was simulated in the BBO crystal pumped by a laser with watt-level power. The amplitudes and conversion efficiencies of the fundamental, and harmonic beams and temperature distributions were obtained, together with the time evolution of temperature field and beam intensities. The influence of the pumping power and crystal length on the conversion efficiency and temperature field was analyzed secondly. The results finally showed that the temperature distribution has great influence on the conversion efficiency and beam quality. A compensation for the phase mismatch induced by temperature can well improve the reduction of conversion efficiency induced by the thermal effect, which thus should be considered in practice.
Optically induced light diffraction in photopolymer of fuchsin basic
Authors: Ma Chen  , Zhang Bao-Min  , Zhang Li  , Ma Yu-Feng  , Zhao Wei-Fu  ,   The 7th department, 33rd Institute of China Electronics Technology Group Corporation, Taiyuan 030006, China
Published: December 2020

In the paper, a holographic storage experiment on laser optically induced light diffraction in acrylamide photopolymer thin film is reported, in which the semiconductor laser of 532nm is used as writing and reading light source, and fuchsin basic is used as sensibilizer. The appearance of diffraction rings can readily be explained as being holographic interference fringes formed by the original laser beam and light scattered from internal or surface inhomogeneities in the unexposed photopolymer. According to phase match condition of degenerate four-wave mixing theory, the diffraction cones of double laser beam holographic writing and single laser beam radiative reading are explained separately. The relationship between angle of incidence and diffraction cone angle is deeply studied by using holographic scattering theory with the help of trigonometric functions.
A synthetical simulation and analysis of band-gap and modal field of photonic crystal fiber
Authors: Zhang Xiao-Juan  , Zhao Jian-Lin  ,   Shaanxi Key Laboratory of Optical Information Technology, School of Science, Northwestern Polytechnical University, The Key Laboratory of Space Applied Physics and Chamistry, Ministry of Education, Xi' an 710072, China
Published: December 2020

We present a method for quickly setting up the complex structure model of photonic crystal fiber (PCF) through directly reading the cross-section of photonic crystal fiber (PCF) by MATLAB, and numerically analyzing the band-gap and the modal field distribution in band-gap PCF (PBG-PCF) by combining plane wave method (PWM) with finite difference frequency domain (FDFD) method. Firstly, the frequency and modal effective index in PBG-PCF can be calculated by using PWM. Then, the modal field distribution and others properties of the PBG-PCF can be obtained in certain wavelength and index ranges by using the calculation results above and FDFD method. To validate its applicability, a type of commercial PBG-PCF was discussed and the influences of the structure parameters (crystal lattice structure, "atom" filling fraction, background material index and "atom" index) on the band-gap were systemically analyzed. This analytic method and calculation results may be useful for the design and preparation of the PCF with large band-gap.
Variational principle and its boundary and additional boundary conditions for inverse shape design problem of heat conduction
Authors: Wu Zhao-Chun  ,   School of Construction and Safety Engineering, Shanghai Institute of Technology, Shanghai 200235, China
Published: December 2020

Based on variable domain variational principle (VP), the variational theory of inverse shape design of heat conduction together with the boundary and the additional boundary conditions enforced on the unknown surface which must be satisfied by the problem is established. Incorporating the boundary and additional conditions into the functional makes the mathematic formulation very concise and compact. Through the established VP, both the temperature field and unknown boundary shape can be determined in a coupled way. The numerical method of the variational principle combined with finite element method is presented in the paper.