bluuebunny/crossref_metadata_2025 huggingface dataset:
The self-reconstruction of periodic Bottle beam behind obstacle
Authors: Fan Dan-Dan  , Wu Feng-Tie  , Cheng Zhi-Ming  , Wang Tao  , Du Tuan-Jie  , Zhu Jian-Qiang  ,   College of Information Science and Engineering, Huaqiao University, Quanzhou 362021, China;,   Shanghai institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China
Published: December 2020

In this paper, the self-reconstructing property of periodic bottle beam generated by the Bessel beam interfering behind obstacle is analyzed. Based on the Hankel wave theory, we analyze the principle of self-reconstruction. According to the diffraction theory, we derive the evolution of beam behind an on-axis circular obstacle. The results show that the periodic bottle beam has the self-reconstructing property and the reconstructed beam maintains the beam intensity distribution. The research results are significant for realizing the multi-plane micro-manipulation by using a periodic bottle beam.
Beam-tracking algorithm for composite scattering between low altitude targets and rough surface
Authors: Wang Xiao-Bing  , Wu Zhen-Sen  , Liang Zi-Chang  , Zhang Yuan  ,   School of Science, Xidian University, Xi'an 710071, China;,   The State Key-Lab for Electromagnetic Characters of Environment, Shanghai 200438, China
Published: December 2020

According to the scattering characteristics of target and rough surface in a high frequency region in the presenca a narrow beam illumination, we employ composite multiple scattering beam-tracking algorithm based on the ray tracing method and iterative method of electromagnetic to obtain a quick solution to calculate the near field composite scattering characteristics of target at low altitude and rough surface. Then we calculate the Doppler echoes of the PEC plate and sphere and compare the data with the ones from MLFMM, and find that they are in good agreement with each other. Finally we carry out testing validation of our tank, and calculation resuets are consistent with the test results.
A wave-beam interaction theory for folded-waveguide traveling wave tubes
Authors: Yin Hai-Rong  , Xu Jin  , Yu Ling-Na  , Gong Yu-Bing  , Wei Yan-Yu  ,   High Power Microwave National Key Laboratory, School of Physical Electronics University of Electronic Science and Technology of China, Chendu 610054, China
Published: December 2020

Based on velocity-modulating model, a nonlinear wave-beam interaction theory for folded-waveguide traveling wave tubes is developed. In this theory, the continuing beam is treated as discrete macro-particles with different initial phases. Then beam-wave interaction and energy exchange are analyzed at each crossing point between beam-tunnel and wave-tunnel. Compared with PIC result, the error of output power predicted by this model is within 10%, and the error of saturated length is within 15%. The results of this model are significant for designing folded-waveguide traveling wave tubes.
Polarized beam coherent combination of pulsed fiber
Authors: Ji Xiang  , Zhou Pu  , Wang Xiao-Lin  , Su Rong-Tao  , Lu Qi-Sheng  , Zhao Yi-Jun  ,   College of Opto-electronic Science and Engineering, National University of Defense Technology, Changsha, Hunan 410073, China
Published: December 2020

Polarized beam coherent combination of pulsed fiber laser is studied. The self-organizing passive phase lock of multilevel high power Yb-doped fiber amplifiers is achieved with optical feed-back ring cavity. Polarized beam coherent combination and multi-channel beam coaxial output are realized by using cascade polarized combining configuration. Polarized beam coherent combination of four Yb-doped fiber amplifiers is experimentally demonstrated, The efficiency of coherent combination is up to 91.9%. Stable combination pulsed fiber laser with temporal and spatial characteristic is achieved. This approach provides a feasible technique for power scaling of high-power pulsed fiber laser.
Lensless coherent diffractive imaging with a Fresnel diffraction pattern
Authors: Jiang Hao  , Zhang Xin-Ting  , Guo Cheng-Shan  ,   Department of Physics, Shandong Normal University, Jinan 250014, China
Published: December 2020

Coherent diffractive imaging is a new lensless imaging technique which has important applications in optical measurements, microscopic imaging and adaptive optics. We propose a method for coherent diffractive imaging from one single Fresnel diffraction intensity pattern. In this method, a Fresnel diffraction intensity pattern of the object wave passing through a specially designed sampling array is recorded and the complex amplitude of the object wave can be extracted through some digital processing such as inverse Fresnel transform and spatial filtering to the recorded intensity pattern; and then the image of the object can be reconstructed in computer. Some theoretical analyses and digital simulations about how the diffraction parameters affect the rebuilding image are given, such as sampling aperture, diffraction distance, image sensor size, etc. We find that there exists an optimal recording distance when the pinhole size and the recording aperture are given. Some serious noise will appear if the recording distance is longer than the optimal value, while shorter recording distance will result in a worse resolution of the reconstructed image. The influence of the pinhole size on the imaging resolution power of the system is also discussed. As this method requires only a single measurement of the diffraction intensity pattern and it does not need any iterative algorithm and lens systems, it provides a practically valuable approach to real-time wavefront measuring and lensless diffractive imaging of a complex-valued object in a wide rang of wavelengths.
Experimental study on spectral characteristics of room temperature operated pulsed quantum cascade laser
Authors: Tang Yuan-Yuan  , Liu Wen-Qing  , He Ya-Bai  , Ruan Jun  , Xu Zhen-Yu  , Yao Lu  , Kan Rui-Feng  ,   Key Lab. of Environmental Optics & Technology, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China
Published: December 2020

Mid-infrared lasers are very effective for the spectroscopic measuring of the fundamental absorption lines for most gases. The quantum cascade laser (QCL), with the advantages of high power, wide tuning range and room-temperature operation, is one of the ideal mid-IR sources for trace gas detection. In this paper, the spectral characteristics of room temperature operated pulsed QCL with a cental wavelength of 1274 cm-1 is presented. By using high-bandwidth HgCdTe detector and high-speed data acquisition devices, and combining with a high-resolution etalon, the features of the spectrum in the frequency domain can be acquired. Analysis of the measured spectral data gives the information about spectral shape, tuning characteristics and resolution variation with time, also about the influences of voltage and temperature on spectrum. The effective way to improve the spectral resolution and optimize the spectral quality is obtained, and it can be used to improve the accuracy of spectrum quantitative analysis.
Fabrication tolerances in four analytical designs of geodesic lenses
Authors: Li Jie  , Zhu Jing-Ping  ,   Key Laboratory for Physical Electronics and Devices of the Ministry of Education, and Shaanxi Key Lab of Information Photonic Technique, the School of Electronic and Information Engineering, Xi'an Jiaotong University, Xi'an 710049, China
Published: December 2020

Waveguide geodesic lenses are key basic components in guide wave optical devices. Since their focus characteristics are independent of the wavelengths and the moded of the guided waves. Geodesic lenses lend themselves extremely well to the integrated optical devices. In this paper, the effects of fabrication errors of geodesic lenses described by four improved analytical solutions are studied by numerical analysis. The relations between the changes of the focal length and the depth changes due to fabrication errors of these lenses are obtained and compared. Considering the use of geodesic lenses in integrated optical devices, the fabrication tolerances of these lenses are given.
Analysis of 532nm long pulse laser-induced thermal decomposition damage to GaAs by semi-analytical method
Authors: Bi Juan  , Jin Guang-Yong  , Ni Xiao-Wu  , Zhang Xi-He  , Yao Zhi-Jian  ,   School of Science, Changchun University of Science and Technology, Changchun 130022, China;,   School of Science, Nanjing University of Science and Technology, Nanjing 210094, China;,   China Research and Development Academy of Machinery Equipment, Beijing 100089, China
Published: December 2020

Considering the fact that the GaAs has the characteristics of thermal decomposition, the thermal decomposition damage to GaAs surface, induced by a 532 nm wavelength long pulse laser with a millisecond pulse width is studied by the heat conduction theoretical and semi-analytical method. First, the calculation models of two-dimensional axisymmetric transient temperature field and the surface thermal decomposition damage threshold for long pulse laser irradiation of GaAs are established, and the transient temperature fields and the thermal decomposition damage thresholds in GaAs with different absorption rates are simulated. The results show that the higher absorption rate causes the higher temperature rise on the surface of material, but the required decomposition damage energy density is lower. With the increase of laser energy density, the decomposition damage occurs more early. This paper has guiding significance and practical value for investigating the interaction between long pulse laser and GaAs and its damage mechanism.
Research on size effect of direct shear test
Authors: Zhang Qi  , Hou Mei-Ying  ,   Key Laboratory of Artificial Micro- and Nano-Structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan 430072, China;,   Beijing National Laboratory for Condensed Matter Physics, Insitute of Physics, Chinese Academy of Sicenes, Beijing 100190, China
Published: December 2020

The shear behavior of granular material is not only the most important mechanical property but also the most basic technical indicator in an engineering project. Today, it is still widely used, owing to its simplicity in operation. However, unlike common solid material, granular material shows the properties of disorder and non-uniformity. This is due to the formation of complex network force chains in granular medium. This also leads to the size effect of shear stress in granular solid. In this paper, direct shear tests with various sizes of high-precision spherical glass beads and sample aspect ratio are carried out to investigate the size effect of shear stress. It is found that when the particle size of glass bead decreases, or when the number of glass beads increases, the shear stress decreases slightly, while the reduction of the sample aspect ratio will lead to similar changes. The experimental results show that when the sample length is less than 50 times the particle size or aspect ratio less than 0.5, direct shear tests shows a significant size effect. Therefore the result of this investigation suggests that the guidance for current standard direct shear test should be revised.
Vortex axial-symmetrization characterized by fractal dimension
Authors: Luo Zhe-Xian  , Yu Hui  , Ping Fan  , Ma Ge-Lan  ,   Key Laboratory of Meteorological Disaster of Ministry of Education, Nanjing University of Information Science and Technology, Nanjing 210044, China;,   Chinese Meteorological Administration, Shanghai Typhoon Institute, Shanghai 200030, China;,   Laboratory of Cloud-Precipitation Physics and Severe Storms (LACS), Institute of Atmospheric Physics, Chinese Academy of Science, Beijing 100029, China;,   College of Environment Science and Technology, Nanjing University of Information Science and Technology, Nanjing 210044, China
Published: December 2020

The vortex axial-symmetrization is an important dynamical process affecting tropical cyclone track change, and it is identified by previous work, up to now, in terms of vorticity fields rather subjectively. Two-dimensional simulations whose integration time is 48 h using a quesi-geostrophic non-divergence barotropic vorticity equation model are performed. The evolutional processes from an initial non-axial-symmetric vortex to the final axial-symmetric vortex are produced. Fractal dimension DB of the perimeter of the vortex is calculated hourly based on the model output data. The results show that fractal dimension can be used to characterize the vortex axial-symmetrization objectively. Based on DB calculated, the correction coefficients CRD and CVD are calculated to be CRD=-0.70 and CVD=-0.75. They each have a significant correction. Here CRD denotes the correction coefficient between DB and Rm being TC scale parameter, and CVD denotes the correction coefficient between DB and Vmax being tropical cyclone intensity parameter. The relation between the vortex axial-symmetrization and the tropical cyclone parameters may be characterized. The results have potential applications in tropical cyclone forecasting.
Numerical simulation of transient space charge distribution of DC positive corona discharge under atmospheric pressure air
Authors: Liao Rui-Jin  , Wu Fei-Fei  , Liu Xing-Hua  , Yang Fan  , Yang Li-Jun  , Zhou Zhi  , Zhai Lei  ,   State Key Laboratory of Power Transmission Equipment & System Security and New Technology, Chongqing 400044, China;,   Zibo Power Supply Company, Shandong Electric Power Corporation, Zibo 255000, China
Published: December 2020

Corona discharges are usually generated at sharp points, edges or on thin wires where the electric field is strongly concentrated. With the rapid development of extra and ultra high-voltage transmission lines, the air corona discharge becomes one of the critical problems associated with high-voltage lines, which can lead to the deterioration of insulation systems, power loss, radio noise. Corona discharge studies have been undertaken for many years, not only because of the scientific interest in the corona mechanism but also because of its practical engineering importance. Transient space charge distribution effect that is one of the important canses in the process of corona discharge, is closely related to the corona discharge mechanism and onset, self-sustaining. In this paper, we present an improved self-consistent, multi-component and two-dimensional plasma hybrid model for simulating the DC positive corona discharge under atmospheric environment. The model is based on the plasma hydrodynamics and the chemical dynamics, and it includes 12 species and 27 reactions. Besides, the photoionization effect is also considered in the proposed model. The simulation and the experiment on bar-plate electrode configuration with an inter-electrode gap of 5.0 mm at 2-5.5 kV are carried out. The discharge voltage-current characteristics and single pulse waveform are in good agreement with the experimental measurements. Based on this model, the electric field distribution, the electron temperature distribution, and the evolution of charged species distribution are investigated in detail. The results show that distributions of electron temperature and electric field have the same patterns, In the process of discharge, electron density is kept at 1019 m-3 or so. O4+ is dominant compared with the other charged heavy species, and O2+ and N2+ play the key role in secondary electron emission: the unmbers of O2- and O are the largest in negative ions and neutral particle respectively, they play a negligible role in discharge process.
First principles investigation of dynamic performance in the process of lithium intercalation into black phosphorus
Authors: Zeng Xiang-Ming  , Yan Hui-Jun  , Ouyang Chu-Ying  ,   Department of New-energy, Xinyu College, Xinyu 338004, China;,   Department of Physics, Jiangxi Nomal University, Nanchang 330022, China
Published: December 2020

Electronic and atomic structures of LiP5, Li3P7 and LiP, which are formed in the process of lithium intercalation into black phosphorus, are systematically studied and analyzed using first-principles ultrasoft pseudopotential method based on the density functional theory (DFT). By caculating the electronic strucrures of these products, we find that the three products are all of semiconductor band structure, of which band gaps are larger than those of black phosphorus, indicating that the electronic conductivity of the black phosphorus is reduced after lithium has been intercalated into it. We simulate the diffusion of lithium ions in the LiP5, Li3P7 and LiP materials using nudged elastic band (NEB) method, and the diffusion activation energy of lithium ions is obtained firstly through the theoretical calculation. Compare with the results of other electrode materials, our results show that the migration energy barriers of lithium ions in LiP5, Li3P7 and LiP are all low. The diffusion coefficient of lithium ions in LiP5 is about 10-4 m2/s and the diffusion channel is one-dimensional. The diffusion coefficient of lithium ions in Li3P7 is approximately 10-7-10-6 cm2/s and the diffusion channel is three-dimensional. The diffusion coefficient of lithium ions in LiP is approximately 10-8-10-5 cm2/s and the diffusion channel is three-dimensional.
The polarization characteristics of the excitation and emission of surface plasmon polarization in the Ag nanowires
Authors: Chen Yuan-Yuan  , Zou Ren-Hua  , Song Gang  , Zhang Kai  , Yu Li  , Zhao Yu-Fang  , Xiao Jing-Hua  ,   Key Laboratory of Information Photonics and Optical Communications of Beijing University of Posts and Telecommunications, Beijing 100876, China
Published: December 2020

We experimentally investigate the dependences of the surface plasmon polarization (SPP) in the Ag nanowires on the polarizations of the excitation light and the emission light with a wavelength of excitation light 750nm. We find that the excitation and transmission efficiency change obviously with the polarization of incident light. However, the emission light is always linearly polarized light with an unchanged polarization direction. For the nanowires synthesized using a self-seeding process, their ends are axisymmetric. When the direction of the incident light is parallel to these Ag nanowires, the excitation and transmission efficiency of SPP are high. Conversely, when the polarization direction of the incident light is perpendicular to the wire axis, it is very low. For the nanowires with asymmetric ends, when the direction of the incident light has an angle with respect to the Ag nanowires, the excitation and transmission efficiency of SPP are high. While the polarization direction of emission light is always parallel to the wire axis which means that the polarization of the emission light does not depend on the polarization direction of the incident light. The polarization characteristics of the SPP in the thin Ag nanowires can realize the nanoscale manipulation of the intensity and polarization.
Breakdown vovtage analysis of new AlGaN/GaN high electron mobility transistor with the partial fixed charge in Si3N4 layer
Authors: Duan Bao-Xing  , Yang Yin-Tang  , Kevin J. Chen  ,   Key Laboratory of the Ministry of Education for Wide Band-Gap Semiconductor Materials and Devices, School of Microelectronics, Xidian University, Xi'an 710071, China;,   Department of Electronic and Computer Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
Published: December 2020

In order to optimize the surface electric field of the traditional AlGaN/GaN high electron mobility transistor and improve the breakdown voltage and reliability, a new AlGaN/GaN high electron mobility transistor is proposed with the partial fixed positive charges in the Si3N4 passivation layer in this paper. The partial fixed positive charges of the Si3N4 passivation layer do not affect the polarization effect of the AlGaN/GaN heterojunction. The surface electric field tends to the uniform distribution due to the new electric field peak formed by the partial fixed positive charges, which modulates the surface electric field by applying the electric field modulation effect. The high electric fields near the gate and drain electrode decrease due to the new electric field peak. The breakdown voltage is improved from the 296V for the traditional structure to the 650V for the new structure proposed. The reliability of the device is improved due to the uniform surface electric field. The effect of the electric field modulation is explained by the horizontal and vertical electric field distribution between the Si3N4 and AlGaN interface, which provides a scientific basis for designing the new structure with the partial fixed positive charges in the Si3N4 layer. Because of the fixed positive charge compensation, the two-dimensional electron gas concentration increases, and the on-resistance decreases. So, the output current of the new structure increases compared with that of the traditional AlGaN/GaN High Electron Mobility Transistor.
Study of the SOI MOSFET characteristics of high-k gate dielectric with quantum effect
Authors: Cao Lei  , Liu Hong-Xia  ,   Key Lab of Ministry of Education for Wide Band-Gap Semiconductor Materials and Devices, School of Microelectronics, Xidian University, Xi'an 710071, China
Published: December 2020

In the paper, we mainly investigate the SOI MOSFET characteristics of high-k gate dielectric with quantum effect. Self-consistent solutions of Schrdinger and Poisson equation are solved in this paper to obtain carrier wave function in the directiong perpendicular to the SiO2/Si interface and energy level distribution. Based on Young model, the threshold voltage and short-channel effects of SOI MOSFET with high-k gate dielectric are simulated and analyzed. The carrier distribution in inversion layer deviates from the surface with the increase of longitudinal electric field, which is caused by quantum effect. It increases the thickness of effective gate oxide and fluctuation of threshold voltage. Meanwhile, high-k gate dielectric materials can reduce the threshold voltage and restrain the DIBL efficiently. The calculation results matching ISE simulation results show that the model has a high-level accuracy, and faster operation ensures the efficiency of the simulation analysis.
Current transport mechanism in silicon-rich silicon nitride/c-Si heterojunction
Authors: Ding Wen-Ge  , Sang Yun-Gang  , Yu Wei  , Yang Yan-Bin  , Teng Xiao-Yun  , Fu Guang-Sheng  ,   College of Physics Science and Technology, Hebei Univ ersity, Hebei key laboratory of Optic-electronic Information Materials, Baoding 071002, China
Published: December 2020

The n-type Si-rich SiNx film is deposited on a p-type crystalline Si (c-Si) substrate by facing target sputtering technique, and the Si-rich SiNx/c-Si heterojunction device is finally formed. The heterojunction device shows a high rectification ratio (1.3 103 at 2 V) at room temperature. Three distinct regions of temperature-dependence J-V characteristic curve can be identified, where different current density variations are indicated. In the low voltage range the current follows Ohmic behavior. In the intermediate range of voltage the current is governed by tunneling and recombination process, while space-charge-limited current (SCLC), with an exponential distribution of trapping states, dominates the conduction mechanism in the relatively high voltage range.
Structural, magnetic and electrical properties in FexZn1-xO amorphous films
Authors: Wang Feng  , Pan Rong-Xuan  , Lin Hai-Rong  ,   Physics and Information Engineering school, Quanzhou Normal University, Quanzhou 362000, China
Published: December 2020

The FexZn1-xO (x=0.80, 0.86, 0.93)amorphous films were fabricated by RF sputtering method. The films each have a strong ferromagnetism at room temperature. The saturation magnetization Ms can reacl 333.29 emu/cm3 in the as-sputtered Fe0.93Zn0.07O. Magnetism is isotropic. The sample obviously exhibits an anomalous Hall effect, which is different from the polycrystalline FexZn1-xO (x≤ 20%). The samples are of n-type semiconductor, with a carrier concentration of about 1019—1020 cm-3. After being annealed, the samples each present a resistance minimum phenomenon at a low temperature (222 K). The conductive mechanism is of the spin dependent variable range hopping resistance in the low-temperature. The experimental results show that amorphous FeZnO system of high Fe composition is a potential candidate of the new spintronic device materials.
Passivation and stability of thermal atomic layer deposited Al2O3 on CZ-Si
Authors: He Yue  , Dou Ya-Nan  , Ma Xiao-Guang  , Chen Shao-Bin  , Chu Jun-Hao  ,   Suntech Power Co., Ltd., Shanghai 200114, China;,   National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083, China
Published: December 2020

Atomic layer deposited (ALD) aluminum oxide (Al2O3) has been known as an almost-perfect candidate of passivation dielectric layer for PERC-type c-Si solar cell. Its passivation performance and thermal stability are key issues for industrial PERC c-Si solar cell based on screen-printed technology. In this paper, 20 nm and 30nm Al2O3 films are synthesized on the solar grade CZ-Si by thermal atomic layer deposition. The results show that the effective lifetime can reach 100 μs for CZ-Si after annealing and is kept a half after the sintering process in the industrial beltline furnace, and the materials can be used in PERC-type solar cell. The SEM image demonstrates that the blisters occur in a thicker Al2O3 film, which explains why the passivation and thermal stability of 30 nm film are inferior to those of 20 nm film.
Photoelectric catalytic properties of silicon solar cell used in microbial fuel cell system
Authors: Chen Zhao  , Ding Hong-Rui  , Chen Wei-Hua  , Li Yan  , Zhang Guo-Yi  , Lu An-Huai  , Hu Xiao-Dong  ,   State Key Laboratory for Artificial Microstructure and Mesoscopic Physics School of Physics, Peking University, Beijing 100871, China;,   The Key Laboratory of Orogenic Belts and Crustal Evolution, School of Earth and Space Sciences, Peking University, Beijing 100871, China
Published: December 2020

Microbial fuel cell (MFC) is a kind of device, which can transform microbial metabolic energy into electric energy and simultaneously degrade the pollutants in wastewater by electrochemical technologies. Currently, the density of output power and efficiency are low and research of MFC is still in laboratory and in developing stage. In this paper, we design a kind of novel MFC system in which the semiconductor photocatalysis cooperating with the microbial catalysis is used by connecting photovoltaic cells to the traditional MFC systems in series. Thus we achieve a "photovoltaic cells-microbial cell" new MFC system. Experiments show that open-circuit voltage, short-circuit current and maximum output power density are greatly improved in the novel MFC system when the photovoltaic cells are exposed to the illumination. Photocatalysis of the semiconductor improves the reaction rate in the cathode chamber and the anode chamber, contributes part of power to runing the novel MFC system, and provides the basis for improving the pollutant degradation rate in wastewater. It is of great significance to solve the problem of energy crisis and environmental pollution.
Design and implementation of four-dimensional variational data assimilation system constrained by the global spectral model
Authors: Zhang Wei-Min  , Cao Xiao-Qun  , Song Jun-Qiang  ,   School of Computer Science, National University of Defense Technology, Changsha 410073, China
Published: December 2020

The mainstream data assimilation system in operation will still employ four-dimensional variational data assimilation(4DVAR) method in a long time of future. We develop a new 4DVAR system, i.e., YH4DVAR, using global spectral model as a constraint to impose a dynamic balance on the assimilation. The cost function of YH4DVAR consists of four terms: background, observations, digital filter, and bias correction, respectively. YH4DVAR employs the wavelet background error convariance, the multi-resolution incremental formulation, the tangent linear and adjoint models for dynamics core and physical processes, and ATOVS radiance data assimilation. Simultaneous spatial and spectral variations of horizontal and vertical covariance are achieved by dividing the control vector into several parts, each of which corresponds to a band of total spherical wavenumbers. Using NWP consisting of YH4DVAR and global spectral model, the anomaly correlation with the verifying analysis for geopotential height 8-day forecast on the 500 hPa isobaric surface at 12-month mean is above 60%. The formulation and implementation of YH4VAR are described in detail in this paper.
Riemann theta function and other several kinds of new solutions of nonlinear evolution equations
Authors: Taogetusang  , Bai Yu Mei  ,   The College of Mathematical, Inner Mongolia University for Nationalities, Tongliao 028043, China;,   The College of Mathematical Science, Inner Mongolia Normal University, Huhhot 010022, China
Published: December 2020

Riemann theta function and other several kinds of new solutions to the second kind of elliptic equation are obtained to construct the infinite sequence complexiton solutions of nonlinear evolution equations. Based on this, applying Bcklund transformation and nonlinear superposition formula of the solutions to the second kind of elliptic equation and Riccati equation, mKdV equation is chosen as an example to seek infinite sequence new complexiton solutions with the help of symbolic computation system Mathematica, which are composed of Riemann theta function, Jacobi elliptic function, hyperbolic function, triangular function and rational function in several forms.
Exact traveling wave solutions for simplified model of Gross-Pitaevskii equation in the 1D-Tonks-Girardeau gas
Authors: Xu Yuan-Fen  ,   Junior College, Zhejiang Wanli University, Ningbo 315101, China
Published: December 2020

By using a dynamical system method, in this paper studied are some exact traveling wave solutions and dynamic behaviors of these traveling wave solutions for simplified model of Gross-Pitaevskii (GP) equation in the 1D-Tonks-Girardeau gas. The effects of the behaviors on the parameters of the systems are also studied. Under different parametric conditions, six exact explicit parametric representations of the traveling wave solutions for simplified model of GP equation in the 1D-Tonks-Girardeau gas are given.
Barrier scattering properties in spin-orbit coupled Bose-Einstein condensate
Authors: Li Zhi  , Wang Jian-Zhong  ,   Department of Physics, Beijing Institue of Technology, Beijing 100081, China;
Published: December 2020

In this paper, the phenomenon of double barrier scattering in spin-orbit coupling Bose-Einstein condensate is studied and the analytical expression of transmission coefficient of the system is therefore obtained. On the basis of the above study, how to deal with Klein tunneling and bound Dirac particles is also discussed to devise an experimental scheme of trapping Dirac particles in captivity. Besides, numerical simulation of the barrier scattering pattern of Dirac particles is performed in this paper by the time splitting spectral method. Through the analysis of transmission situation of Dirac particles directing at the Klein barrier in both the center and margin part of blocked area and the study of the influence of non-linear interaction on the evolution of Dirac particles from both repelling and attracting effect, the conclusion can be drawn that although the influence of non-linear interaction on scattering property of particles is negligible to some extent, the strong non-linear interaction will completely destroy the momentum distribution of wave packets so that the result of barrier scattering of Dirac particles can be dramatically changed.
Adaptive control of chaotic systems based on model free method
Authors: Wang Yue-Gang  , Wen Chao-Bin  , Yang Jia-Sheng  , Zuo Zhao-Yang  , Cui Xiang-Xiang  ,   The Second Artillery Engineering University, Xi’an 710025, China
Published: December 2020

Conventional chaos control methods need model information of the chaos system, but model parameter is always unknown in engineering practice and the dynamic uncertainty of model-building often appears inevitably. In this case it is impossible to acquire best control performance index of optimization. To resolve this problem an adaptive control algorithm of chaotic systems based on model free method is proposed. It is a low cost controller. With this method, we can easily know a priori knowledge of chaos system only be adjusting a few parameters online without training before hand. We prove that this algorithm has a good stability mathematically. Simulation results show the effectiveness of this theory.
First-principles study on the luminescence property of In-doped ZnTe
Authors: Linghu Jia-Jun  , Liang Gong-Ying  ,   School of Science, Xi’an Jiaotong University, Xi’an 710049, China
Published: December 2020

First-principles theory is adopted to analyze the characteristics of defects in ZnTe induced by In doping. The geometry structures, formation energies, band structures, densities of states and transition levels of the defects are calculated. The results show that there are two kinds of major defects in In-doped ZnTe. One is the atomic substitution defect of Zn replaced by In, which gives rise to a transition level located at 2.6 eV beneath the conduction band. The other is a complex defect, consisting of one In substituting Zn and one nearby Zn vacancy, which results in a transition level 0.33 eV higher than the top level of valance band. Electron transition between these two transition levels can be regards as the origin of the near-infrared light observed experimentally in In-doped ZnTe.
General laws of reflection and refraction for metasurface with phase discontinuity
Authors: Sun Yan-Yan  , Han Lu  , Shi Xiao-Yu  , Wang Zhao-Na  , Liu Da-He  ,   Applied Optics Beijing Area Major Laboratory, Department of Physics, Beijing Normal University, Beijing 100875, China;,   Key Laboratory of Nondestructive Test (Ministry of Education), Nanchang Hangkong University, Nanchang 330063, China
Published: December 2020

The general reflection and refraction laws at the metasurface with an abrupt phase shift are derived by two methods based on Fermat's principle and the boundary conditions of continuity, it is found that one or two critical angles for total internal reflection exist not only when a light beam impinges on the optical sparse material from the optical denser material, but also when a light beam spreads from the optical sparse material to the optical denser material. Anomalous reflection and refraction, such as, negative reflection and negative refraction may occur when a light beam passes through the metasurface, and the conditions of their occurrence are given. Finally, a kind of metasurface based on one-dimensional phase mask is designed to control the light propagation.
Study of the focusing features of spatial amplitude and phase modulated radially polarized vortex beams in a 4pi focusing system
Authors: Chang Qiang  , Yang Yan-Fang  , He Ying  , Liu Hai-Gang  , Liu Jian  ,   Department of Physics, College of Science, Shanghai University, Shanghai 200444, China
Published: December 2020

The focusing properties of phase and amplitude modulated radially polarized vortex beams in a 4pi focusing system are theoretically investigated near the focal plane by using Richards-Wolf vectorial diffraction method. The amplitude modulation of vortex beams can be adjusted by changing the start integration value. The phase modulation of vortex beams can be realized by adding liquid crystal variable retarder with the phase delay angle δ. The simulated results show that multiple spherical spots can be obtained near the focus of the 4pi focusing system with the decrease of amplitude. The phase delay angle δ of the input beams can generate extruding effect for the electrical field distribution near the focus of the 4pi focusing system. Some special intensity distributions can be obtained by changing topological charge m and phase delay angle δ. Optical chain can be generated in the case of m=1. Dark channel can be obtained in the case of m=2. These special focusing beams can also transform with phase modulation. With the increase of phase δ, the multiple spherical spots at m=0 change slowly into an optical chain, and finally become a dark channel. In contrast, the optical chain at m=1 changes slowly into multiple spherical spots; and the dark channel at m=2 changes into the superposition of optical spherical spots and the optical chain. These special focusing beams have potential applications in optical trapping and micro-manipulation.
A quantum secret sharing scheme based on two polarization beam splitters
Authors: Wei Ke-Jin  , Ma Hai-Qiang  , Wang Long  ,   School of Sciences, Beijing University of Posts and Telecommunications, Beijing 100876, China;,   Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
Published: December 2020

In this paper we present a quantum secret sharing scheme based on a single qubit protocol using two polarization beam splitters. This scheme guarantees an auto compensation of birefringence and phase jitter in single mode fiber and optical device. The visibility is higher than 99.3% over 5 km communication distance with an excellent stability.
Optical design of a reflective concentrator mirror utilizing higher order cylindrical surfaces
Authors: Qin Hua  , Lei Cheng-Xin  , Liu Han-Fa  , Ge Shuo-Shuo  ,   Department of Sciences, Shandong University of Technology, Zibo 255049, China
Published: December 2020

In this paper, we present a new and highly efficient solar concentrating mirror. It is composed of partial high-order cylinder inner wall which is determined by two sets of specific coefficients a2, a4, a6, a8, a10, a12, a14, a16 and C. According to the higher-order cylindrical equation and the optical law of reflection, the relationship between the direction vectors of sunbeams reflected from the cylindrical inner wall and the coefficients of a higher order polynomial equation, a2,a4, a6, a8, a10, a12, a14, a16 and C is derived. By optimizing these coefficients, all sunbeams incident on the inner wall of higher-order cylinder can be reflected and focused into a very thin line segment parallel to the cylindrical busbar, which means line focus. Two sets of particular coefficients associated with the high- order cylindrical surface are obtained by using particle swarm optimization algorithm. The focusing effect of the solar concentrating mirror, defined by the particular set of coefficients, is demonstrated by using computer simulations. The concentrator mirror has a light compression ratio of about 148 : 1 and its linear spot can be used as a strong light source or a high temperature heat source. The higher-order cylindrical mirror can be made of metal or glass in three steps: cutting, grinding, and polishing, and may also be formed by a higher order cylindrical framework and an aluminized polyester film laid on the framework.
Novel microwave power sige heterojunction bipolar transistor with high thermal stability over a wide temperature range
Authors: Lu Dong  , Jin Dong-Yue  , Zhang Wan-Rong  , Zhang Yu-Jie  , Fu Qiang  , Hu Rui-Xin  , Gao Dong  , Zhang Qing-Yuan  , Huo Wen-Juan  , Zhou Meng-Long  , Shao Xiang-Peng  ,   College of Electronic Information and Control Engineering, Beijing University of Technology, Beijing 100124, China
Published: December 2020

Thermal instability of power SiGe heterojunction bipolar transistor (HBT) at high current over a wide temperature range restricts the applications of the device in RF and microwave circuits. In order to improve the thermal instability, the influences of Ge profile in a base region on the electrical and thermal characteristics of microwave power SiGe HBT are studied with the aid of the model of multi-finger power SiGe HBT established by SILVACO TCAD. It is shown that for the HBT with graded step Ge profile, a higher cut-off frequency fT can be achieved due to the accelerating electric field caused by the graded step Ge concentration in the base region when compared with the device with uniform Ge profile. The influences of temperature on current gain β and fT are weakened, which avoids the drift of electrical characteristics over a wide temperature range. Although the temperature of device is lowered, the temperature of each emitter finger is still non-uniform. Considering the difference in heat dissipation among emitter fingers, a new device with non-uniform emitter finger spacing in layout and a graded step Ge profile in base region is designed. For the new device, the uniformity of temperature among emitter fingers is achieved, higher fT is kept, β and fT are less sensitive to temperature variation. Hence the thermal instability is obviously improved compared with the device with uniform emitter finger spacing and uniform Ge profile in base region, indicating the superiority of the new device at high current over a wide temperature range.
Formation of all carbon heterojunction: through the docking of carbon nanotubes
Authors: Jiao Xue-Jing  , Ouyang Fang-Ping  , Peng Sheng-Lin  , Li Jian-Ping  , Duan Ji-An  , Hu You-Wang  ,   School of Physics and Electronics, Central South University, Changsha 410114, China;,   College of Mechanical and Electrical Engineering, Central South University, The State Key Laboratory of High Performance and Complex Manufacturing, Changsha 410083, China
Published: December 2020

Based on Stone-Wales (SW) defect evolution theory and molecular dynamics, we simulate the docking process of two caped carbon nanotubes (CNTs) of different types to form a heterojunction using Monte Carlo methods. First, an algorithm for a fast simulation of the cap change in CNTs is put forward and the cap formation of single CNTs with open ends is simulated, by applying this method. SW defect evolution is designed as a leap change simulation of these caps, represents C-C bond formation and breakage, while molecular dynamics is used to simulate the gradient change of the relative bond distance between the C atoms. The coalescence process of forming heterojunction is also studied here. These simulations show that the process of docking is first to generate a large number of defects, which will precipitate the coalescence, then many defects disappear through the compound, finally the remaining defects transfer to the ends of this heterojunction in the form of pentagon/heptagon rings, thus leading to the reduced overall energy.
Molecular dynamics simulation of polyethylene/silver-nanoparticle composites
Authors: Li Lin  , Wang Xuan  , Sun Wei-Feng  , Lei Qing-Quan  ,   Key Laboratory of Engineering Dielectrics and Its Application, Ministry of Education, Heilongjiang Provincial Key Laboratory of Dielectric Engineering, School of Electrical and Electronic Engineering, Harbin University of Science and Technology, Harbin 150080, China
Published: December 2020

Molecular dynamics simulations of polyethylene/silver-nanoparticle composites are implemented to calculate the structures, electrical, thermal and mechanical properties, thereby investigating their relationships with the nanoparticle dimension and simulation temperature. The results show that polyethylene/silver-nanoparticle composites are of isotropic amorphous structure, and the dispersion of nanoparticles in composite can be enhanced at a relatively higher temperature. Multi-layers of atoms on nanoparticle surface change into amorphous configurations, and electrical polarization interface layers are formed between silver nanoparticles and polyethylene matrix. The interface region shrinks and expends respectively with nanoparticle dimension and temperature increasing. Compared with polyethylene system, the polyethylene/silver-nanoparticle composite presents explicitly high polarizability which increases with temperature and nanoparticle size rising simultaneously. The silver nanopaticle dimension directly influences the intensity and frequency of interfacial dipole moment, resulting in corresponding variations of peak position and intensity in infrared spectrum. The polyethylene/silver-nanoparticle composite also shows higher isometric heat capacity and negative thermal pressure coefficient with better temperature stability, which decreases explicitly with temperature and nanoparticle size increasing respectively, than polyethylene system. The mechanical property of polyethylene/silver-nanoparticle composite shows isotropic elastic constant tensor with considerably higher Young modulus and Poisson ratio than the polyethylene system, both of which decrease with temperature and nanoparticle dimension increasing, which indicates the improvement on mechanical property with Ag nanoparticle filler.
Phase-field simulation of solidified microstructure evolution in the presence of lateral constraint
Authors: Du Li-Fei  , Zhang Rong  , Xing Hui  , Zhang Li-Min  , Zhang Yang  , Liu Lin  ,   Key Laboratory of Space Applied Physics and Chemistry, Ministry of Education, School of Science, Northwestern Polytechnical University, Xi’an 710072, China;,   State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi'an 710072, China
Published: December 2020

Lateral constrain in the presence of melting has a significant effect on microstructure evolution of crystal growth, and this effect is related to the size and property of lateral constrain, thus determining microstructure formation during solidification. In the paper, microstructure evolution in the presence of lateral constrain during the solidification of pure Ni metal is simulated using a non-isothermal phase-field model. Effects of size and properties of lateral constrain are simulated and studied, also microstructures formed at different initial dendritic arm distances are discussed. Results indicate that the presence of lateral constrain has a direct influence on pattern evolution which determines the microstructure formation. Microstructure changes significantly with lateral constrain distance turning small, initial constrain temperature low becoming low and initial dendrite arm distance growing. Different heights of lateral constrains have almost the same effects on microstructure change during solidification.
Theoretical study of the ground and excited state properties of newly designed size-expanded adenine analogue x-adenine
Authors: Zhang Lai-Bin  , Ren Ting-Qi  ,   School of Physics and Engineering, Qufu Normal University, Qufu 273165, China;,   College of Science, Shandong University of Science and Technology, Qingdao 266590, China
Published: December 2020

Recently, creating unnatural fluorescent nucleobase analogues has gained increasing attention. In this work, a detailed computational investigation on the photophysical properties of the fluorescent adenine analogue x-adenine (xA) is carried out. The ten lowest low-lying exited states are analyzed and assigned. The effects of methanol solution, linking to deoxyribose, and base pairing on its absorption and emission processes are considered. The calculated excitation and emission energies are in good agreement with the measured data available. It is found that linking to deoxyribose and methanol solution have a hyperchromic effect on xA. Also it is found that methanol solution and linking to deoxyribose will lead to the red shift of fluorescence, while base pairing does not have obvious effects on the lowest ππ* state and fluorescence emission but produces the blue shift of lowest nπ* to some extent.