bluuebunny/crossref_metadata_2025 huggingface dataset:
Pulling monatomic chain from graphene by nano probe
Authors: Cao Rong-Gen  , Wang Yin  , Lin Zheng-Zhe  , Ming Chen  , Zhuang Jun  , Ning Xi-Jing  ,   (1)Department of Materials science, Fudan University, Shanghai 200433, China; (2)Department of Optical Science and Engineering, Fudan University, Shanghai 200433, China; (3)Institute of Modern Physics, Fudan University, Shanghai 200433, China;Department of Nuclear Science and Technology,  Fudan University,  Shanghai 200433,  China;Applied Ion Beam Physics Lab, Key Lab of the Ministry of Education, China
Published: December 2020

Considering that free monatomic chain containing hundreds of atoms has not been prepared so far, an experiment method for preparing monatomic carbon chain from graphene by nano probe is proposed based on classical molecular dynamics simulation. We show that longer monatomic carbon chain can be pulled out from the zigzag edge of graphene by C60 tip with the pulling speed of 1 m/s at room temperature.
The theoretical study of metal-insulator transition of VO2
Authors: Chen Jun  , He Jie  , Lin Li-Bin  , Song Ting-Ting  ,   (1)Department of Physics and Electronic Information, China West Normal University, Nanchong 637002, China;Department of Physics and Key Laboratory for Radiation Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064, China;Instit; (2)Department of Physics and Key Laboratory for Radiation Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064, China; (3)Institute of Applied Physics and Computational Mathematics, Beijing 100088, China
Published: December 2020

The first principle methods have been used to investigate the electronic structure and thermal property of VO2 in rutile or monoclinic phase. The strong electronic correlation of V(3d) was described by the local density plus Hubbard U approximation, and the phonon density of states of the two phases were calculated by using perturbation density function theory. Our calculated results showed that the energy level of x2-y2 orbital of V(3d) exhibits an separation in the electronic density of stats when VO2 transfer from metallic states to insulator state. The calculated equation of states of VO2 at zero temperature discovered a pressure-induced M—I phase transition at 68 GPa. The pressure-induced M—I phase transition can be due to the strong correlation between V(3d, 3s) and O(2p) orbital. Furthermore, based on the Gibbs free energy, we found that the temperature-induced phase transition is at 375 K. This is in agreement with the experimental result.
S-shaped J-V characteristic of a-Si:H/c-Si heterojunction solar cell
Authors: Zhong Chun-Liang  , Geng Kui-Wei  , Yao Ruo-He  ,   School of Electronics and Information Engineering, South China Universityof Technology, Guangzhou 510640, China
Published: December 2020

In this paper the physical mechanism of the S-shaped J-V characteristics of (p) a-Si:H/(n) c-Si heterojunction solar cell at low working temperatures, low impurity concentrations in the a-Si:H layer, high valence band offsets or high interface defect densities is studied by heterojunction interface analysis and AMPS simulations. The results show that the barrier at the amorphous/crystalline interface hinders the collection of photogenerated holes. A high hole accumulation at the interface, in combination, causes a shift of the depletion region from the c-Si into the a-Si:H. This leads to the electric field decreasing, and the enhanced recombination inside the c-Si depletion region causes a significant current loss. It results in the S-shaped J-V characteristics.
A method for constructing infinite sequence complexiton solutions to nonlinear evolution equations
Authors: Taogetusang  ,   The College of Mathematical Science, Inner Mongolia Normal University, Huhhot 010022, China
Published: December 2020

To seek new infinite sequence complexiton solutions to nonlinear evolution equations(NEE(s)), the formula of nonlinear superposition of the solutions and Bcklund transformation of Riccati equation are presented, and as an illusrative exapmle, the generalized Boussinesq equation is chosen to obtain new infinite sequence complexiton solutions with the aid of symbolic computation system Mathematica, which includes complexiton solutions of hyperbolic function, triangular function type with rational function and hyperbolic function with triangular function. The method is of significance to construct infinite sequence complexiton solutions to other NEEs.
Circuit implementation and control of a new fractional-order hyperchaotic system
Authors: Huang Li-Lian  , Xin Fang  , Wang Lin-Yu  ,   College of Information and Communication Engineering, Harbin Engineering University, Harbin 150001, China
Published: December 2020

In order to improve the complexity of chaotic signals, a new fractional-order four-dimensional hyperchaotic system is presented. Some dynamical properties of the system are investigated. The circuit implementation of this new system is simulated using Multisim. The results prove that chaos actually exists in the system with order as low as 3.2. A simple linear feedback controller is designed, and the simulation results are presented to demonstrate the effectiveness of the method.
A fast algorithm without static error for generalized predictive control of Hénon chaotic system
Authors: Chen Zhi-Wang  , Liu Wen-Long  ,   (1)Key Laboratory of Industrial Computer Control Engineering of Hebei Province, Yanshan University, Qinhuangdao 066004, China; (2)Key Laboratory of Industrial Computer Control Engineering of Hebei Province, Yanshan University, Qinhuangdao 066004, China;The Applied Technology College of DaQing Petroleum Institute, Qinhuangdao 066004, China
Published: December 2020

A kind of fast generalized predictive control algorithm without static error for Hénon chaotic system is proposed. Firstly, the chaotic system is identified by improved recursive least squares parameter of time-varying forget factor. Then the softness factor is adjusted on line through combining MP neural network with BP algorithm, thus the fast tracking without static error of reference signa1 is realized by introducing the feedforward gain matrix and softening coefficient matrix into regular performance index function of generalized predictive control. The algorithm avoids the matrix inversion computation and has strong ability of tracking the reference signal. The simulated results show the effectiveness of this algorithm.
Study on intensity distribution inside the frequency conversion crystals for continuous phase plate front-located in inertialconfinement fusion driver
Authors: Zhan Jiang-Hui  , Yao Xin  , Gao Fu-Hua  , Yang Ze-Jian  , Zhang Yi-Xiao  , Guo Yong-Kang  ,   College of Physics Science and Technology, Sichuan University, Chengdu 610064, China
Published: December 2020

This paper studies the intensity distribution inside the frequency conversion crystals when the continuous phase plate (CPP) is placed in 1ω light of final optics assembly for inertial confinement fusion (ICF) driver. Our study shows that the modulation of 1ω light caused by CPP makes the frequency conversion efficiency and the uniformity of intensity field inside the frequency conversion crystals decrease. It leads to the possibility of laser induced damage for frequency conversion crystals to increase. What worth paying special attention to is: the modulation and maximum intensity in the vicinity of entrance and exit surface of frequency conversion crystal is much higher than in other areas, so the possibility of laser induced damage is also relatively greater there. However, if the intensity of 1ω light before the frequency conversion system becomes even greater, for the normal running of final optics assembly the modulation and maximum intensity inside the frequency conversion crystals should be confined within the permitted range.
Characteristics of dual-wavelength vertical-cavitysurface-emitting lasers
Authors: Guan Bao-Lu  , Guo Xia  , Zhang Jing-Lan  , Ren Xiu-Juan  , Guo Shuai  , Li Shuo  , Chuai Dong-Xu  , Shen Guang-Di  ,   Key Laboratory of Opto-electronics Technology, Ministry of Education, Beijing University of Technology, Beijing 100124, China
Published: December 2020

Based on asymmetric one-dimensional photonic crystal structure,a dual-wavelength vertical-cavity surface-emitting laser (VCSEL) with modified standing wave field distribution has been constructed. The defect layer is Al0.8Ga0.2As with 5λ/4 thickness. Specifically, the dual-wavelength output spectrum of the VCSEL has low absorption loss, easy wavelength adjustment and same output direction. In addition, the two wavelengths and their spacing could be tuned by changing the refractive index contrast of the asymmetric PC structure and the thickness of defect layer. Such dual-VCSEL structure can be applied in optical bistable switches, amplifiers, modulators and detectors, etc..
High-frequency modulation, high-power and narrow-linewidth distributed feedback fiber laser
Authors: Xue Li-Fang  , Zhang Qiang  , Li Fang  , Zhou Yan  , Liu Yu-Liang  ,   Institute of Semiconductors, Chinese Academy of Sciences, Beijng 100083, China
Published: December 2020

A kind of narrow-linewidth fiber laser was developed. A segment of Er-doped fiber is connected after the active phase-shifted fiber grating. A distributed feedback (DFB) fiber laser is realized using a 980 nm laser for pump. The erbium ions in the Er-doped fiber are pumped from ground-state to excited state by the residual pump power, so the output power of the DFB fiber laser is amplified effectively, and the pump power is fully used. In this way, the power consumption and the cost are reduced greatly. Temperature-control techniquc is used to deal with the temperature-sensitivity of the DFB fiber laser. The high-frequency modulation is realized by using a piezo-electric actuator when the phase-shifted fiber grating is mounted on its surface. In our experiment, the highest modulation frequency, the output power and the linewidth of the fiber laser are 2 kHz, 15.6 dBm and 300 kHz, respectively.
Method for determining the characteristic parameters of the turbulence based on the measurement of M2-factor
Authors: Pan Ping-Ping  , Zhang Bin  ,   College of Electronics Information, Sichuan University, Chengdu 610064, China
Published: December 2020

Based on the extended Huygens-Fresnel principle and theory for the turbulence, the analytical expression for the beam propagation factor (M2-factor) of partially coherent beams propagating in a turbulent atmosphere has been derived. The effects of the structure constant of the refractive index fluctuations C2n and the inner scale of the turbulence l0on the M 2 factor have been analyzed quantitatively. Consequently, a new method for determining the characteristic parameters of the turbulence based on the measurement of the M 2 factor by experiments has been proposed. The results show that the laser beams with better spatial coherence property are more sensitive to the effects of turbulence, so the fundamental Gaussian beams with fully coherence can be used as the source in the measurement, and the usual instruments for measuring the M 2-factor can be adopted as the experiment equipments. It is very simple and convenient to determine the characteristic parameters of the turbulence by applying the method proposed in this paper.
Beam propagation factor of cosh-Gaussian array beams propagating through atmospheric turbulence
Authors: Liu Fei  , Ji Xiao-Ling  ,   Department of Physics, Sichuan Normal University, Chengdu 610068, China
Published: December 2020

The analytical formula for the beam propagation factor ( M 2-factor) of cosh-Gaussian (ChG) array beams propagating through atmospheric turbulence is derived, and the influence of turbulence on the M 2-factor is studied by using the relative M 2-factor. It is shown that the M 2-factor is not a propagation invariant in turbulence, and the turbulence results in an increase of the M 2-factor. For the incoherent combination, the M 2-factor of ChG array beams increases with increasing propagation distance, beam parameter, relative beam separation distance and beam number. For the coherent combination, the M 2-factor of ChG array beams increases with oscillatory behavior as the beam parameter or the relative beam separation distance increases. For the coherent combination the M 2-factor is always smaller than that for the incoherent combination. However, for the incoherent combination the M 2-factor is always less sensitive to turbulence than that for the coherent combination. In particular, the influence of turbulence on the M 2-factor can be reduced by a suitable choice of the relative beam separation distance. With increasing beam number, the M 2-factor becomes more sensitive to turbulence for the coherent combination, while for the incoherent combination the M 2-factor becomes less sensitive to turbulence.
Simulation research on the control of terahertz beam direction by surface plasmon
Authors: Hu Hai-Feng  , Cai Li-Kang  , Bai Wen-Li  , Zhang Jing  , Wang Li-Na  , Song Guo-Feng  ,   Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
Published: December 2020

Based on the temperature-dependent complex dielectric constant of indium antimonide, an InSb-dielectric-InSb plasmonic waveguide structure with the grating was realized. At the frequency of 1 THz, a directional beam was obtained, and its radiation direction can be controlled by changing the temperature difference between the grating structures on each side. Finite difference time domain (FDTD) method was adopted to evaluate the relationship between the off-axis angle of the beam and the temperature difference. The tunable directional beaming can be attributed to the grating coupling of the TM surface modes in plasmonic waveguides.
The study of defects in Ga0.946Mn0.054As by X-ray absorption spectra
Authors: Qiao Yuan-Yuan  , Xiao Zheng-Guo  , Cao Xian-Cun  , Guo Hao-Min  , Shi Tong-Fei  , Wang Yu-Qi  ,   Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences,Hefei 230031,China
Published: December 2020

The influence of the major compensating defects As antisites (AsGa) and Mn interstitials (MnI) in the Ga0.946Mn0.054As diluted magnetic semiconductor (DMS) were studied by X-ray absorption spectra (XAS). The experimental results show that the defects in Ga0.946Mn0.054As grown at lower temperature (TS=200℃) is mainly AsGa, but at TS>230℃ MnI is the major defects. On the other hand, a higher LT-annealing temperature (250℃) can remove MnI out of the Ga0.946Mn0.054As lattice, and the highest Curie temperature (TC=130 K) is reached. Moreover, it is indicated that the LT-annealing process can increase the number of MnGa atoms by reducing the concentration of AsGa defects and driving MnI defects to fill up the holes left by AsGa.
Optoelectronic or all-optical logic gates using chaotic semiconductor lasers using mutual coupling-feedback
Authors: Yan Sen-Lin  ,   Department of Physics and Electronic Engineering, Nanjing Xiaozhuang University, Nanjing 211171, China
Published: December 2020

We present theoretically the construction of the fundamental gates using two injection semiconductor laser diodes by muans of mutual coupling-feedback. Two laser diodes driven by a common monochromatic light beam run chaos while chaotic synchronization between the two lasers is achieved by coupling-feedback. The optoelectronic logic gate is implemented by appropriately synchronizing or de-synchronizing the two chaotic states by modulating the currents. The all-optical logic gate is finally implemented by appropriately synchronizing or de-synchronizing the two chaotic states via the modulators modulating the coupling lights, which is an external optical modulation method. Numerical results validated the feasibility of the method.
Adaptive synchronization of fractional-order chaotic system via sliding mode control
Authors: Zhang Ruo-Xun  , Cao He-Fei  ,   (1)College of Physics, Hebei Normal University, Shijiazhuang 050016, China; College of Elementary Education, Xingtai University, Xingtai 054001, China; (2)College of Physics, Hebei Normal University, Shijiazhuang 050016, China; Department of Physics, Shijiazhuang College, Shijiazhuang 050035, China
Published: December 2020

Based on sliding mode control theory and adaptive control theory, this paper investigates the synchronization of three-dimensional chaotic systems, designs a fractional order proportional integral switching surface, and proposes a single adaptive-feedback controller for fractional-order chaos synchronization. Simulation results for fractional-order unified chaotic system and Arneodo chaotic systems are provided to illustrate the effectiveness of the proposed scheme.
Shot noise measurement methods in electronic devices
Authors: Zhuang Yi-Qi  , Bao Jun-Lin  , Sun Peng  , Wang Ting-Lan  , Chen Wen-Hao  , Du Lei  , He Liang  , Chen Hua  ,   (1)School of Microelectronic , Xidian University , Xi’an 710071, China; (2)School of Technology Physics , Xidian University , Xi’an 710071, China
Published: December 2020

The limitations to shot noise measurement methods based on superconducting quantum interference device (SQUID) and superconductivity-insulation-superconductor (SIS) Josephson junction are pointed out, and a method to measure the shot noises of conventional electronic devices is proposed. Shot noise characteristics of conventional electronic devices are analyzed, and then a low-temperature measurement system is established. By using a double-shielding construction and low noise preamplifier, the test system can achieve a good electromagnetic interference shielding and low background noise. The theoretical and the experimental results of shot noises in diodes at 10 K are in good agreement with each other. The accuracy and the credibility of measurement system are proved.
Beam-wave synchronization and coupling in a multi-gap coupled cavity
Authors: Cui Jian  , Luo Ji-Run  , Zhu Min  , Guo Wei  ,   (1)Key Laboratory of High Power Microwave Sources and Technologies, Institute of Electronics, Chinese Academy of Sciences, Beijing 100190, China; (2)Key Laboratory of High Power Microwave Sources and Technologies, Institute of Electronics, Chinese Academy of Sciences, Beijing 100190, China; Graduate University of Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

The analytical expressions of the beam-wave coupling coefficients and the beam-loaded conductance in an N-gap coupled cavity are derived based on space-charge wave theory. Through calculating the relations of the beam-wave coupling coefficient and the normalized beam-loaded conductance to the gap number, beam voltage and perveance for 2π mode, the mechanism of the beam-wave synchronization and coupling in the multi-gap coupled cavity are discussed. The results show that, with the increase of N(≥2), the beam-wave coupling efficiency and the normalized beam-loaded conductance vary with beam voltage more rapidly and there is a maximum value for the absolute squared value of the coupling coefficient |MN|2 and a maximum value and a minimum value for the normalized beam-loaded conductance gb. The magnitudes of these extrema increase with the increase of gap number N, and the corresponding voltage is close to the synchronization voltage. The increase of the perveance could make the voltage difference between two extremums of gb increase, the magnitudes of these extrema decrease, and the beam-wave coupling efficiency fall.
Theoretical calculation of valence shell ionization potentials of XF3(X=N, P, As) using the equation-of-motion coupled cluster method
Authors: Tang Hai-Yan  , Chen Heng-Jie  , Zhou Xue-Ping  , Cheng Xin-Lu  ,   (1)Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, China; (2)Patent Examination Cooperation Center of SIPO, Beijing 100190, China; (3)School of Mathematics and Physics, Chongqing University of Science and Technology, Chongqing 401331, China
Published: December 2020

The equation-of-motion coupled cluster method with full inclusion of singles and doubles (EOM-CCSD) is applied to evaluate the vertical ionization potential (VIP) of XF3(X=N,P,As). At the same time, symmetry adapted cluster configuration interaction (SAC-CI), the outer valence shell Green function (OVGF) and partial third order approximation (P3) are also employed. Comparison with results of some experiments show average errors of 0.2 eV in the whole valence shell ionization region and are better than OVGF and P3 values and similar to the SAC-CI values. With the increase of basis set, the difference of the first VIP value between the EOM-CCSD and experimental becomes smaller and the different is about 0.03 eV. According to results from SAC-CI, OVGF, P3 and EOM-CCSD of NF3 and PF3, we can conclude that the first IP of AsF3 is not 12.3 eV but about 12.8 eV, the valence shell ionization potentials are 12.64,15.23,16.30,17.37,18.05 and 21.98 eV.
The axial distribution of carbon dioxide cluster in supersonic gas jet by Rayleigh scattering
Authors: Fu Peng-Tao  , Han Ji-Feng  , Mou Yan-Hong  , Han Dan  , Yang Chao-Wen  ,   College of Physics Science and Technology, Sichuan University, Key laboratory of Radiation Physics and Technology(Sichuan University),Ministry of Education , Chengdu 610064, China
Published: December 2020

The axial distribution of carbon dioxide clusters in supersonic gas jet was studied by Rayleigh Scattering method. It is found that the logarithm of scattering signal ln(S) decreases linearly with the square root of Z and the position of 4 mm rather than the position nearest the nozzle has the maximum average cluster size. The scattering signal intensity exhibits a power scaling on the backing pressure ranging from 6 to 17 bar , and the power varies from 3.6 to 4.2. The axial cluster size was estimated and the maximum size was found to be 16 000 molecules/cluster.
Theoretical and experimental study on transmission properties of THz wave in metal-coated hollow waveguide
Authors: Zhou Jun  , Tan Xiao-Ling  , Geng You-Fu  , Yao Jian-Quan  ,   College of Physics Science and Technology, Shenzhen Key Laboratory of Sensor Technology, Shenzhen University, Shenzhen 518060, China; Institute of Laser and Optoelectronics, College of Precision Instrument and Optoelectronics Engineering, Tianjin Universi;,   Department of Physics, Faculty of Science, Ningbo University, Ningbo 315211, China;,   Department of Physics, Faculty of Science, Ningbo University, Ningbo 315211, China; Institute of Laser and Optoelectronics, College of Precision Instrument and Optoelectronics Engineering, Tianjin University, Tianjin 300072, China;,   Institute of Laser and Optoelectronics, College of Precision Instrument and Optoelectronics Engineering, Tianjin University, Tianjin 300072, China
Published: December 2020

Limited by serious material absorption and dispersion in THz wave band, efficient and long distance delivery of THz signal is one of important problems for constructing a compact THz system. Based on the transmission loss coefficient in metal waveguide obtained by perturbation method, the transmission loss properties of THz wave in metal-coated hollow waveguide varying with different metal materials and waveguide structure parameters are simulated. According to the numerical results, an Ag-coated hollow waveguide with inner diameter of 1.1 mm was designed and fabricated, and the transmission loss of THz wave was 8.6 dB/m at frequency of 2.5 THz as found in experiment, which realizes a short distance transmission with ultralow loss in THz region.
Sub-wavelength imaging of the two-dimensional photonic crystal with effective index close to -1
Authors: Tong Yuan-Wei  , Tian Shuang  , Zhuang Song-Lin  ,   (1)College of Optical and Electronics Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China; (2)College of Science,University of Shanghai for Science and Technology, Shanghai 200093, China; (3)College of Science,University of Shanghai for Science and Technology, Shanghai 200093, China; College of Optical and Electronics Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China
Published: December 2020

This paper aims at designing a 2D photonic crystal (PC) with negative refractive index close to -1. Plane wave expansion method (PWEM) is used to obtain the band diagram and its equal-frequency surface (EFS). And the finite difference time domain (FDTD) simulation method is also used to analyze the equivalent refractive index of the PC. The results show the equivalent refractive index of the PC close to -1 within a certain frequency band. A super-lens is formed by this photonic crystal, which can form a non-near-field image. Moreover, the super-lens has the capability of sub-wavelength imaging with its effective index close to -1.
Fabrication of triangular chirped fiber Bragg grating and its application in single-sideband modulation based radio over fiber system
Authors: Li Jing  , Ning Ti-Gang  , Pei Li  , Zhou Qian  , Hu Xu-Dong  , Qi Chun-Hui  , Gao Song  , Yang Long  ,   Institute of Lightwave Technology, Beijing Jiaotong University, Beijing 100044, China
Published: December 2020

In this work, we present an approach for fabricating triangular chirped fiber Bragg grating. Application of single-sideband modulation based radio over fiber system employing this grating is also analyzed. The proposed technology is based on phase mask and index modulation with changing velocity. A triangular fiber Bragg grating with 1.9 nm base width of transmission spectrum and 0—15 dB of transmission depth was fabricated experimentally. Due to the negative slope in transmission spectrum, the grating can be used in the radio over fiber system. In the proposed scheme, only a single grating is used to achieve two functions, i.e. OSSB+C generation from DSB modulation signals, and reducing the carrier to sideband ratio of the generated signals. Numerical calculation and simulation ware performed and some discussions are given.
Study on dispersion compensation property of octagonal photonic crystal fibers
Authors: Zhang Li-Chao  , Hou Lan-Tian  , Zhou Gui-Yao  ,   Institute of Infrared Optical Fibers and Sensers Technology, Yanshan University, Qinhuangdao 066004, China
Published: December 2020

The dispersion compensation property of octagonal photonic crystal fibers (PCFs) was simulated with multipole method in this paper.It was found that the dispersion, dispersion slope and Kappa parameter of PCFs can be designed precisely but changing the air hole size and the pitch in PCFs cladding.We compared photonic crystal fiber of hexagonal structure with that of octagonal structure, both of which have the same structure parameters. It was found that the octagonal structure easily abtains large negative dispersion and low non-linear coefficient. It was demonstrated that the octagonal structure has huge potential in designing diepersion compensation PCFs. So, we designed a novel PCF with octagonal structure.The PCF achieves a negative dispersion of -1434.9 ps·nm-1·km-1 and a negative dispersion slope of -4.6338 ps·nm-2·km-1 at λ=1.55 μm, which is far better than the conventional fibre.
Analysis of theoretical model of thermal infrared imager based on the substrate-free focal plane array
Authors: Jiang Xing-Kai  , Zhang Qing-Chuan  , Shi Hai-Tao  , Mao Liang  , Cheng Teng  , Wu Xiao-Ping  ,   Key Laboratory of Mechanical Behavior and Design of Materials of Chinese Academy of Sciences,University of Science and Technology of China , Hefei 230027 China
Published: December 2020

Based on thermal deformation of bi-material microcantilever, the focal plane array (FPA)of uncooled optical readout infrared(IR) imaging system has undergone a development from substrate array to substrate-free array. The experimental imaging result and finite element method (FEM) analysis indicated that the substrate-free focal plane array (FPA) did not accord with the condition of constant frame temperature. This paper proposed a new theoretical model on thermal transmission of substrate-free FPA with electrical analogy method. Considering the system as a whole, the analysis of complex thermal interaction of adjacent elements could be averted while the heat absorption and transmission of frame could be considered. The temperature of outer frame was set to be equal to the ambient temperature as a boundary condition. Although it was not so flexible compared with FEM analysis when dealing with the boundary condition, the theoretical model was proved to correspond with the experimental result, and could be used as an approximate formula in thermal response calculation of substrate-free FPA. The model avoids the complication of FEM analysis, especially for large arrays. Further more, the model can be used for substrate-free FPA dimensions design and optimization under certain response target.
Slow-wave electromagnetic instability driven by wiggling relativistic electron beam in ion-channel
Authors: Wang Zhen-Yu  , Tang Chang-Jian  ,   College of Physical Science and Technology, Sichuan University, Chengdu 610065, China
Published: December 2020

The slow-wave electromagnetic (EM) instability excited by a relativistic electron beam (REB) injecting plasmas has been studied using linear electromagnetic hydrodynamic (EMHD) theory. The features of multiple waves propagation are presented. The results of numerical calculation prove that the EM instability occurs in slow-wave band. The necessary and sufficient condition of the EM instability has been found. Both analytic discussion and physical analysis reveal that the electron betatron motion is one of important factors for the EM instability. The physical mechanism of the instability driven by the electron betatron motion has been discussed.
Double screen frequency selective surface structure optimized by genetic algorithm
Authors: Wang Jian-Bo  , Lu Jun  ,   School of Science, Changchun University of Science and technology, Changchun 130022,China
Published: December 2020

Double screen frequency selective surface(FSS) is a very effective means of realizing the invisibility of radar-cabin from the detection of radar wave since it can well realize the flattened effect and rapid decrease. In this paper, the thickness, the dielectric constant, the element graph and the arrangement periodicity of an FSS medium are investigated by Genetic Algorithm(GA) when electromagnetic waves are incident on the double screen FSS at varying angles, and an optimized FSS structure and transmission characteristics are obtained. Meanwhile, the relevant experimental samples are prepared by means of coating and lithography and are tested in microwave anechoic chamber. The results show that the optimized structure has a better stability with respect to incident angle of electromagnetic wave under the condition of 2GHz operation, thereby laying the foundation for the application of double screen FSS to curved surfaces at wide angles.
Measurement of magnetic anisotropyby ferromagnetic resonance
Authors: Gu Wen-Juan  , Pan Jing  , Du Wei  , Hu Jing-Guo  ,   College of Physics Science and Technology,Yangzhou University,Yangzhou 225002,China
Published: December 2020

The effective magnetic field caused by exchange coupling between a ferromagnetic and an antiferromagnetic bilayer and its magnetic anisotropy have been investigated by means of ferromagnetic resonance. It was shown that the exchange bias phenomenon occurrence and its positive or negative characteristic for ferromagnetic/antiferromagnetic bilayer can be identified from its magnetic resonance spectrum. In addition, when the field was applied along different crystalline directions, the behavior of magnetic resonance field will be changed, and is closely dependent on the magnetocrystalline anisotropy and unidirectional anisotropy induced by the interface coupling in ferromagnetic/antiferromagnetic bilayer. Anomalies in the ferromagnetic resonance frequency studied as functions of applied field, including its orientation and strength, are interpreted as evidence for the four fold anisotropy and unidirectional anisotropy. Our conclusions are in good agreement with the related experiments.
Failure mechanism of PZT 95/5 under direct currentand pulsed electric field
Authors: Zhang Fu-Ping  , Du Jin-Mei  , Liu Yu-Sheng  , Liu Yi  , Liu Gao-Min  , He Hong-Liang  ,   State Key Laboratory for Shock Wave and Detonation Physics Reseasch, Institute of Fluid Physics, Mianyang 621900, China
Published: December 2020

The failure mechanism of PZT 95/5 under direct current and pulsed electric field is studied by experiment and theoretical analysis in this paper. The electrothermal coupled failure is the key mode when the PZT 95/5 is subjected to direct current. But when the pulsed electric field is applied to the PZT 95/5, the resonance effect and the relation between energy and frequency being considered, the vibrant energy shifts to high frequency and the possibility of electromechanical-coupled failure is increased with decreasing pulse duration. When the pulse duration is increased, the failure behavior transfers gradually from mechanical coupled with electric failure to direct current failure mode.
Study on the surface morphology and absorptivity of light-absorbing materials
Authors: Su Fa-Gang  , Liang Jing-Qiu  , Liang Zhong-Zhu  , Zhu Wan-Bin  ,   (1)State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun, 130033, China; (2)State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun, 130033, China; Graduate School of the Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

Different types of surface morphology have different effects on multiple reflection of optical materials for absorbing light and have significant influence on absorptivity of materials. A suitable surface morphology can increase the effective absorptivity of optical materials. In this paper, we simulate the multiple reflection effects of V-shaped surface, Sine-shape surface, normal or uniform obliquity distribution surface and normal height distribution surface with the ray tracing method, and then analyse the capabilities of increasing the absorbtivity and the characteristics of incident angle of light on the four types of surfaces. The common necessary condition for increasing absorbtivity of these surfaces is obtained by obliquity analysis, i.e. the mean obliquity of the surface should be larger than 30 degrees at least, and the advantages of the V-shape surface to increase absorptivity under normal incidence are analysed.
Synthesis and characterization of the grinding compoundlevel diamond by pure Fe catalyst
Authors: Qin Jie-Ming  , Ying Zhang  , Cao Jian-Ming  , Tian Li-Fei  ,   (1)College of Materials Science and Engineering, Changchun University of Science and Technology, Changchun 130022, China; (2)College of Materials Science and Engineering, Changchun University of Science and Technology, Changchun 130022, China; Physical College, Inner Mongolia University for the Nationalities, Tongliao 028000, China
Published: December 2020

The synthesis process of grinding compound level diamond by the pure Fe catalyst-graphite system under high temperature and high pressure was reported, and the P-T phase diagram was given. On this basis, the colorless and transparent grinding compound level diamond was synthesized through the adjustment of technical parameters. By controlling the growth speed of recrystallization of graphite and diamond, and the problem of diamond being opaque and presence of inclusions when synthesized by the pure Fe catalyst was solved. According to the analysis of Mmössbauer and Fourier infrared spectroscopy, the inclusions and content of nitrogen element were characterized. Based on clarifying the formation mechanism of inclusions, the solutions to reducing inclusions were achieved. It also demonstrated the reason why the color of diamond synthesized by the pure Fe catalyst turned tinted.
Information communication of the northern hemisphere on intra-seasonal and over inter-annual oscillation signals
Authors: Sun Shu-Peng  , Feng Ai-Xia  , Gong Zhi-Qiang  , Feng Guo-Lin  , Wang Qi-Guang  ,   Department of Atmospheric and Sciences Lanzhou University, Lanzhou 730000, China;,   Department of Atmospheric and Sciences Lanzhou University, Lanzhou 730000, China; Laboratory for Climate Studies, National Climate Center, China Meteorological Administration, Beijing 100081, China;,   Laboratory for Climate Studies, National Climate Center, China Meteorological Administration, Beijing 100081, China;,   Laboratory for Climate Studies, National Climate Center, China Meteorological Administration, Beijing 100081, China; Beijing Normal University, Institute of Global Change and Earth System Sciences, Beijing 100875, China
Published: December 2020

Basic characteristics and form of intra-seasonal and over inter-annual variations were extracted through filtering using the reanalysis data of monthly geopotential height from NCEP/NCAR. Then information theory was applied to the filtered data to analyze the communication among the intra-systems between the low and mid-high latitudes. The results were found that the information loss rate of intra-seasonal oscillation signal is higher than that of over inter-annual signal, and the directions of two signals’ communication are opposite in particular regions. The information loss rate at low latitudes is higher than that at mid-high latitudes for both time scale signals, and it is distinct between the lands and the oceans in meridional average. With respect to the altitudes, the information loss rate of over inter-annual oscillation signal at low latitudes is rather high, but it is low at mid-high latitudes over all troposphere and bottom of stratosphere. For the intra-seasonal oscillation signal, the information loss rate is high at low altitude but low at high altitude. The study of communication between the low latitude and mid-high latitude of the circulation system on the two time scales provides a new way to understand the predictability and interaction of different parts in the climate system.
Mei symmetry leading to Mei conserved quantity of generalized Hamiltonian system
Authors: Jiang Wen-An  , Luo Shao-Kai  ,   Institute of Mathematical Mechanics and Mathematical Physics, Zhejiang Sci-Tech University, Hangzhou 310018, China
Published: December 2020

For a generalized Hamiltonian system, Mei conserved quantity derived by using Mei symmetry is studied. First, the definition,the criterion and the determining equations of Mei symmetry of generalized Hamiltonian system are given under infinitesimal transformations of group. Second, the conditions and the forms for existence of Mei conserved quantity are directly obtained by using the Mei symmetry of the system. Then, the theorem for existence of Mei conserved quantity of generalized Hamiltonian system with additional terms is given. Finally, a new three-dimensional generalized Hamiltonian system and the plane motion of the three vortices of three-body problem are studied by using the method presented in the paper.
Experimental simulation of quantum entanglement distribution over a high-loss channel
Authors: Yin Juan  , Yong Hai-Lin  , Wu Yu-Ping  , Peng Cheng-Zhi  ,   Hefei National Laboratory for Physical Sciences at the Microscale, Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China
Published: December 2020

We experimentally simulate entanglement distribution and demonstrate the violation of Bell’s inequality over 70 dB channel loss. Imaging a communication system which is composed of a satellite-based entangled photon source at a height of 350 km, two satellite-based transmitting telescopes each with a diameter of 13.5 cm, and two receiving telescopes each with a diameter of 100 cm on the ground station. At a minimum ground elevation angle of 10°, the attenuation for optical links to two ground stations over thousand kilometers is comparable to that we have achieved. Furthermore, theoretical and experimental studies demonstrate the key technology researches in entanglement distribution with high loss. First of all, we should reduce the dark noise and raise the time resolution of the system. On this basis, with the brightness enhancement of the source, the system is tolerant of higher link attenuation and long communication distance.
A method of digital secure communication based on a cellular automata with rapid dispersion of errors
Authors: Wang Fu-Lai  ,   School of mathematics and statistics, Zhejiang University of Finance and Economics, Hangzhou 310012, China
Published: December 2020

An improved one-dimensional cellular automata is designed in which the key space is large with pseudo random series on a shift map and perturbed terms and thus data expansion is avoided. Random triggering rules are involved. There is no complex computation, but a large amount of information can be processed every time. The stream cipher generated by the automata is proved to be of ideal randomness and avalanche effect with rapid dispersion velocity of errors. Empirical results show that the stream cipher is perfectly random both globally and locally. The chi-square test(confidence 95%) on a set of stream cipher with a length of 24000 and its 400 time iterations shows that the passing rates of frequencies and series are above 95% and 100%, respectively. To test the sensitivity of the data, 1 bit is changed at any position of the key stream and the average variation rate of total bits is 49.99%, ranging from 49% to 51% (theoretical value is 50%), and variance is 1.193 ·10－5, which means that the automata is a good encryption technique.
Intermittent synchronizing fractional unified chaotic systems
Authors: Hu Jian-Bing  , Zhang Guo-An  , Zhao Ling-Dong  , Zeng Jin-Quan  ,   (1)School of Computer Science and Engineering, University of Electronic Science and Technology, Chengdu 610054, China; (2)School of Electronics and Information, Nantong University, Nantong 226019, China
Published: December 2020

Stability about fractional chaotic system is studied and a theory about fractional chaotic system is proposed and proved under intermittent control in this paper. Based on the theorem, a controller is designed to realize the intermittent synchronizing fractional unified chaotic system. Numerical simulation demonstrates the effectiveness of the theorem.
Observation on the spatial distribution of air pollutants by active multi-axis differential optical absorption spectroscopy
Authors: Wang Zhuo-Ru  , Zhou Bin  , Wang Shan-Shan  , Yang Su-Na  ,   Department of Environmental Science and Engineering, Fudan University, Shanghai 200433, China
Published: December 2020

An active 4-axis differential optical absorption spectroscopy system is developed in the project. The system has 4 telescopes integrated together that can simultaneously project and receive 4 independent light beams for measurement. The 4 beams share one xenon short-arc lamp as the light source. Each telescope can be adjusted individually to point to different reflectors. The angle between different beams can be adjusted up to 28°. A test is conducted on the system with four beams setting to measure the concentration of NO2 in the same area. The comparison shows good consistency between measurement data from different beams: the correlation coefficient (R2) between the data from any two beams is no less than 0.97 and the average difference between different beams is below 1×10-9. The long-term observations on the vertical distributions of NO2 and SO2 around Fudan University reveal the average feature of its daily variation: the concentration of NO2 shows a variation of double-peak in a day, the 2 peaks occur in the early morning and the evening respectively, while the valleys occur in the afternoon and the wee hours; the layer of 44—66 m has the highest NO2 concentration, while the layer of 66—88 m the lowest; during the nighttime, inter-layer difference of NO2 concentration is higher than that during the daytime and can be as high as 17×10-9; the concentration of SO2 shows a variation of single-peak in a day, the peak occurs in the forenoon; the vertical distribution of SO2 is relatively even, with the inter-layer difference below 3×10-9.
Material opto-electronic properties of In, N co-doped SnO2 studied by first principles
Authors: Lu Yao  , Wang Pei-Ji  , Zhang Chang-Wen  , Jiang Lei  , Zhang Guo-Lian  , Song Peng  ,   School of Science, University of Jinan, Jinan 250022, China
Published: December 2020

In this paper we use first-principles full potential linearized augmented plane wave method (FP-LAPW) to inwestigate density of states (DOS), band structure and optical properties of the materials that doped with In and N. The results show that the doping structure has fine locat levels in both the spin-down direction and the spin-up direction and both state densities are symmetrical. The local levels are produced in the spin-down direction in the band gap, and co-doped compounds show being semi-metallic. The energy band structure indicates that the two co-doped compounds are still direct band gap semiconductors. The top of valence band shifts toward the low energy with the increase of the concentration of N, so obviously the band gap is widened. The main dielectric peak of imaginary part of dielectric function exists only at 8.58 eV, the position of main peak shifts to ward the right and the peak intensity increases significantly. The static dielectric constants of two different concentrations of N-doped structure also significantly increase, and a strong interaction takes place between the states of N 2p and In 5s. The number of peaks of co-doped absorption spectra reduces and the range of absorption wavelength is broadened.
Atomic-scale study of structural change of TiAl alloy film during the cooling process
Authors: Song Cheng-Fen  , Fan Qin-Na  , Li Wei  , Liu Yong-Li  , Zhang Lin  ,   College of Science, Northeastern University, Shenyang 110004, China
Published: December 2020

Microstructural changes of molten TiAl films are investigated by using molecular dynamics simulations within the framework of embedded atom method in quenching and continuous cooling processes. Atomic local structures in these films are analyzed by using atom average energy, pair distribution functions, and pair analysis technique. The local structure changes in the TiAl films can be divided in to three stages on quenching, and they are divided in to two stages on continuous cooling.
Efficient generation of ultra-broadband supercontinuum in the mid-infrared polarization gating
Authors: Liu Kun-Long  , Hong Wei-Yi  , Wang Shao-Yi  , Zhang Qing-Bin  , Lu Pei-Xiang  ,   Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, China
Published: December 2020

We theoretically investigate the process of the efficient ultra-broadband supercontinuum generation in the mid-infrared polarization gating. The polarization gating at 2000 nm is adopted to restrict the recombination of the electron into one-half optical cycle and extend the spectrum cut-off to 270 eV. And a 0.5 fs ultraviolet pulse is synthesized to the polarization gating to control the ionization process. Then the harmonic intensity is enhanced by 4—5 orders, and a 240eV supercontinuum is obtained, supporting a 16 as pulse generation. By filtering out different ranges of the supercontinuum, isolated 110 as pulses with tunable central wavelengths are efficiently generated.