bluuebunny/crossref_metadata_2025 huggingface dataset:
Feature analysis in frequency domain of Duffing system based on general local frequency
Authors: Tang You-Fu  , Liu Shu-Lin  , Lei Na  , Jiang Rui-Hong  , Liu Ying-Hui  ,   School of Mechatronics Engineering and Automation, Shanghai University, Shanghai 200072, China;,   School of Mechanical Science and Engineering, Northeast Pertroleum University, Daqing, Heilongjiang 163318, China
Published: December 2020

Owing to the limitations of the concept of frequency for power spectrum and the inherent defects of Fourier transform, a novel concept of general local frequency is proposed. Based on a approach to adaptive peak decomposition, the dynamic feature in frequency domain varying with parameter r of Duffing system driven by periodic signal is investigated. And a phenomenon of frequency bifurcation is found. Moreover, coninuous frequency bands exist near the central frequency of chaos time seriers at different values of parameter r and their shapes are similar. By demodulation analysis of Hilbert transform, the modulation characteristic and modulation similarity of chaos time seriers are summarized. The above study shows that the proposed approach to general local frequency based on adaptive peak is effective for freature extraction in frequency domain of Duffing system. It provides a new method to observe a continunous distribution of frequency bands for the non-linear system in chaotic state.
Redundancy-test-based hyper-parameters selection approach for support vector machines to predict time series
Authors: Yu Yan-Hua  , Song Jun-De  ,   The School of Computer, Beijing University of Posts and Telecommunications, Beijing 100876, China
Published: December 2020

The selection of hyper-parameters is a crucial point in support vector machine modeling. Different from previous method of choosing an optimal model by using basic statistics of residuals in, the new approach selects hyper-parameters by checking whether there is redundant information in residual sequence. Furthermore, omni-directional correlation function (ODCF) is used to test redundancy in residual, and the accuracy of the method is proved by theoretical analysis and numerical simulation. Experiments conducted on benchmark time series, annual sunspot number and Mackey-Glass time series, indicating that the proposed method has better performance than the recorded in the literature.
Precision spectroscopy of helium using a laser-cooled atomic beam
Authors: Sun Yu  , Feng Gao-Ping  , Cheng Cun-Feng  , Tu Le-Yi  , Pan Hu  , Yang Guo-Min  , Hu Shui-Ming  ,   Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei 230026, China
Published: December 2020

The 23P0,1,2 fine structure interval of 4He can be determined to 10-8 accuracy both theoretically and experimentally. It can be used either to determine the fine structure constant or to test the quantum electrodynamics theory. To reach this goal, it is necessary to measure the fine structure splitting to sub kHz accuracy by increasing the signal-to-noise ratio and eliminating the systematic deviations. In the experimental configuration of present study, transverse laser cooling is used to obtain an intense metastable helium atom beam. The triple state metastable atoms are also bent from the original atomic beam to reduce the background noise. The spectral scanning will be accomplished by tuning the sideband of a frequency-locked diode laser to maintain sufficient frequency stability during the scan. The experimental method has been tested on the setup recently built, and the analysis shows that a sub-kHz precision is feasible.
Mass shift effect on relativistic high-order harmonic generation
Authors: Guo Fu-Ming  , Chen Ji-Gen  , Yang Yu-Jun  , Zeng Si-Liang  ,   Institute of Atomic and Molecular Physics, Jilin University, Changchun 130012, China;,   Department of Physics and Materials Engineering, College of Physics and Electronic Engineering, Taizhou University, Taizhou 318000, China;,   Science and Technology Computation Physics Laboratory, Institute of Applied Physics and Computational Mathematics, Beijing 100088, China
Published: December 2020

By solving the time-dependent Dirac and Schrödinger equations, we investigate the super high-order harmonic generation (HHG) from a one-dimensional model atom in a relativistic intense laser pulse. Our numerical simulations show that the relativistic results can be degraded to non-relativistic ones in the weak laser field, and the clear effect of the relativistic mass-shift can be gradually observed as the increase of the laser field intensity. Furthermore, the cutoff frequency and the emission efficiency of the HHG spectrum are analyzed by the wavelet time-frequency analysis and the relativistic "three-step" model.
The P-branch emission spectral lines in the 2Δ3/2-12Δ3/2 system of VO molecule
Authors: Liu Wei-Ning  , Fan Qun-Chao  , Sun Wei-Guo  , Feng Hao  , Hu Shi  ,   School of Material Science and Engineering, Research Center for Advanced Computation, Xihua University, Chengdu 610039, China;,   School of Physics and Chemistry, Research Center for Advanced Computation, Xihua University, Chengdu 610039, China;,   Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, China
Published: December 2020

The accurate P-branch emission spectra of the (0, 0) band in the 2Δ3/2-12Δ3/2 system of the VO molecule are studied in this work using the analytical formula derived by Sun group in their previous work. The calculated results generate correct values of the unknown spectral lines up to J=80.5 which are not available experimentally for this band, as well as reproduce all known experimental spectral lines accurately.
Diffraction efficiency measurement of large aperture multilayer dielectric grating and its application in the fabrication process
Authors: Zhou Xiao-Wei  , Liu Ying  , Xu Xiang-Dong  , Qiu Ke-Qiang  , Liu Zhen-Kun  , Hong Yi-Ling  , Fu Shao-Jun  ,   National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, China
Published: December 2020

Large aperture multilayer dielectric grating (MDG) is one of the key elements of high-power laser systems. In order to meet the requirements for large aperture MLG in a high-power laser system, a diffraction efficiency measurement system is developed for characterizing the diffraction efficiency of large MDG at 1064 nm and Littrow mounting. Through analyzinge the main factors such as detector signal-to-noise ratio and operating staff, which influence the testing results during measurement, their difference is obtained to be less than ±1%, which proves that the method can be used to measure the diffraction efficiency of MDG. Based on a large number of experimental data, the optical characterization of MDG in a negative first-order Littrow configuration could provide some information about grating microstructure. So the diffraction efficiency measurements have a number of important applications in the fabrication process, as a nondestructive grating inspection tool, such as determining the suitable photoresist grating mask which meet the ion beam etching requirements, on line end-point detection during ion beam etching, and judging whether another etching is needed. Based on above techniques, a number of MDGs have been achieved, each of which has mean diffraction efficiency greater than 95% line density 1740 lines/mm, and aperture up to 430 mm×350 mm. The results show that this method can satisfy the requirements for simple operation, testing speediness and preciseness, in which any inspection is not necessary for the MDG microstructure paramters.
Measurements of transient reflectance spectra of dynamic gratings by optical frequency modulation
Authors: Xu Pan  , Hu Zheng-Liang  , Ma Ming-Xiang  , Jiang Nuan  , Hu Yong-Ming  ,   School of Optoelectronic Science and Technology, National University of Defense Technology, Changsha 410073, China
Published: December 2020

The characteristics of dynamic gratings greatly affect the linewidth and mode stability of ultra-narrow linewidth erbium-doped fiber (EDF) lasers. In this paper, we propose a novel method to measure the temporal evolution of the reflectance spectra of the dynamic gratings recorded in EDF based on the transient effect of the erbium ions by applying optical frequency modulation on the written light. The transient reflectance spectra of the linear configuration dynamic gratings are measured, and the influences of the written optical power and the terminal reflectivity on the response characteristics of the gratings are also studied. Experimental results show that the first order zero point frequency of the gratings formed in a 3-m-long erbium doped fiber is 30 MHz which accords with the value obtained from the steady state theory. The relative reflectivity change decreases with the increase of input optical power or terminal reflectivity. The measured maximal changes occur at low input power or terminal reflectivity. The grating building time also decreases with the increase of optical power, and it is less than 1 ms when input power is larger than 4 times the saturable power. This phenomenon can be explained by the process of two-wave mixing.
Investigation of the collapse of laser-induced bubble near a cone boundary
Authors: Li Bei-Bei  , Zhang Hong-Chao  , Han Bing  , Chen Jun  , Ni Xiao-Wu  , Lu Jian  ,   School of science, Nanjing University of Science & Technology, Nanjing 210094, China
Published: December 2020

The effect of the cone boundary on collapse of the laser-induced bubble is investigated under the assumption of virtual plane, and the methods of shadow photography, optical beam deflection and simulation are also used to obtain the effect of cone angle on the bubble dynamics. The results indicate that the effects of the cone angle on the shape of bubble, collapse time and the formation of liquid jet are obvious. The degree of departure of bubble shape from spherical shape and the collapse time are found to increase with the increase of cone angle, and the valid liquid jet is able to form at a lager cone angle. The experimental value and theoretical value of collapse are in good agreement with each other, and the assumption of virtual plane and the modification of dimensionless distance parameter proposed in this study are valid.
The method of quantitative characterization using reflection pulsed thermography
Authors: Tao Ning  , Zeng Zhi  , Feng Li-Chun  , Zhang Cun-Lin  ,   Beijing Key Laboratory for Terahertz Spectroscopy and Imaging, Key Laboratory of Terahertz Optoelectronics, Ministry of Education, Department of Physics, Capital Normal University, Beijing 100048, China;,   Institute of Physics and Electronic Engineering, Chongqing Normal University, Chongqing 400047, China
Published: December 2020

In this paper, a new method using reflective pulsed thermography to measure defect depth, thermal wave reflection coefficient and thermal diffusivity is presented. First, a brief description of the pulsed thermography in terms of theoretical background and quantitative measurement is given. One stainless steel 304 structure machined several flat-bottom holes in which it is filled with different materials are used as experimental sample, the measured results of defect depth, thermal diffusivity and reflection coefficients at defect interface under different conditions are given. The agreement between the results obtained by using pulsed thermography and the value presented in the literature or measured by other techniques appears satisfactory within errors of 5%, and possible reasons for affecting the measurement precision are discussed.
The effect of the proton layer initial size on the proton beam characteristic in target normal sheath acceleration
Authors: Yu Jin-Qing  , Zhou Wei-Min  , Jin Xiao-Lin  , Li Bin  , Zhao Zong-Qing  , Cao Lei-Feng  , Dong Ke-Gong  , Liu Dong-Xiao  , Fan Wei  , Wei Lai  , Yan Yong-Hong  , Qian Feng  , Yang Zu-Hua  , Hong Wei  , Gu Yu-Qiu  ,   Vacuum Electronics National Laboratory, University of Electronic Science and Technology of China, Chengdu 610054, China;,   Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

The proton beam accelerated by the interaction of laser with plasma has practical applications in radiography of dense plasma, fast ignition in inertial confinement fusion, and cancer treatment. The application domain is determined by the characteristic of the proton beams, which is affected by a lot parameters. In order to investigate the effect of the initial size of the proton layer, the two-dimensional Particle-In-Cell (2D-PIC) code Flips2D is used. The total energy of proton beam vs. time is studied, and the relation between the duration of acceleration and the period of laser pulse is obtained. The effects of the proton layer initial width and thickness on the divergence angle and the energy spectrum of the proton beam are investigated. The relation between the proton beam characteristics and proton layer initial size is obtained.
Investigation of a energy conversion silicon chip based on 63Ni radio-voltaic effect
Authors: Gao Hui  , Luo Shun-Zhong  , Zhang Hua-Ming  , Wang He-Yi  ,   Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

Aiming at the main problem encountered in the research of radioisotope microbattery based on β radio-voltaic effect-enhancement of energy transfer efficiency and radiation damage as mutually constraining sides of a contradiction, an investigation of radiation-induced defects in different silicon wafers by low-energy electron irradiation was carried out and the electrical characteristic measurement for two types of PIN structures indicated that P+I (N-) N+ device in I zone with a dopant concentration of 2× 1012 cm-3 agreed with the predicted result of P, N type silicon radiation damage effect. This was then taken as the prototype device, on which test of 63Ni radiation output characteristics was performed. The test result was compared with the experimental data of Wisconsin University and the major factors causing low energy transfer efficiency were analysed. Adoption of three-dimensional PIN junction structure, increasing the proportion of energy deposition in depletion region, matching I (N-) zone width and deposition depth and controlling the leak current under an order of magnitude of Picoampere were considered to enhance the energy transfer efficiency, based on which energy transfer structure was designed and ultimately structure parameters such as multi-hole PIN structure, radiation source thickness, depletion region width were determined, thus the energy transfer structure optimization was accomplished.
Effect of high pressure treatment on microstructure and resistivity of Cu75.15Al24.85 alloy
Authors: Chen Yan  , Liu Lin  , Liu Jian-Hua  , Zhang Rui-Jun  ,   College of Environmental and Chemical Engineering, Yanshan University, Qinhuangdao 066004, China;,   State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004, China;,   Tangshan Vocational Technology College, Tangshan 063000, China
Published: December 2020

The microstructures of Cu75.15Al24.85 alloy before and after treatment at 15 GPa pressure and 750℃ for 15 min are analyzed by optical metallograph, X-ray diffraction, scanning electron microscopy and differential scanning calorimeter, and its resistivity is also obtained through resistivity measuring instrument. According to the obtained results, the effects of high pressure treatment on the microstructure and resistivity are investigated. The results show that high pressure treatment can refine the microstructure, and increase the resistivity of the alloy. When the pressure is 3 GPa, the refinement is more remarkable and the resistivity reaches a maximal value.
Reliability of SiN-based MIM capacitors in GaN MMIC
Authors: Wang Xin-Hua  , Wang Jian-Hui  , Pang Lei  , Chen Xiao-Juan  , Yuan Ting-Ting  , Luo Wei-Jun  , Liu Xin-Yu  ,   Key Laboratory of Microelectronics Device & Integrated Technology, Institute of microelectronics of Chinese Academy of Sciences, Beijing 100029, China
Published: December 2020

Reliability assessment of SiN MIM capacitors in GaN MMIC is performed by constant voltage stress test. Two kinds of failure modes, critical charge density at which the dielectric breaks down and mean time prior to failure are investigated. The trap energy level in SiN dielectric is obtained by temperature dependent current characteristics. The degradation mechanism of SiN MIM capacitor is analyzed. The research shows that new donor-like traps are generated at dominant position during the stress. And the trap energy level becomes deeper after stress. The increased trap accelerates the scattering of the carrier, which leads to the decrease of leakage current in the end. The investigation on the failure mechanism of SiN MIM capacitor provides a reference for reinforcing the dielectric capacitors.
Electromagnetic wave scattering by a topological insulator prolate spheroid particle
Authors: Zeng Lun-Wu  , Zhang Hao  , Tang Zhong-Liang  , Song Run-Xia  ,   Jiangsu Key Laboratory for Intelligent Agricultural Equipment, College of Engeering, Nanjing Agriculture University, Nanjing 210031, China
Published: December 2020

Using Maxwell equations, we expand electromagnetic field components in spherical coordinate frame by using spherical vector wave function. According to the constitute relations of the topological insulator (TI), we modify transmittance fields and scattering fields. Using boundary conditions of topological insulator, we obtain the scattering electromagnetic fields. Numerical result show that when the time reversal symmetry is broken, the scattering cross sections are influenced by the topological magneto-electric polarizability.
Effects of Gd and Co doping on the electrical and ferromagnetism properties of BiFeO3 ceramics
Authors: Song Gui-Lin  , Zhou Xiao-Hui  , Su Jian  , Yang Hai-Gang  , Wang Tian-Xing  , Chang Fang-Gao  ,   College of Physics & Information Engineering, Henan Normal University, Xinxiang 453007, China;,   Henan Key Laboratory of Photovoltaic Materials, Xinxiang 453007, China
Published: December 2020

Multiferroic Bi0.95Gd0.05Fe1-xCoxO3 (x= 0, 0.05, 0.1, 0.15, 0.2) ceramics were prepared by rapid liquid phase sintering method. We studied effect of Gd and Co doping on the structure, electrical and ferromagnetism properties of BiFeO3 ceramics. The structure and morphology of BiFeO3 ceramics are characterized by X-ray diffraction (XRD). The results show that all the peaks for Bi0.95Gd0.05Fe1-xCoxO3 (x= 0, 0.05, 0.1, 0.15, 0.2) samples can be indexed according to the crystal structure of pure BiFeO3. And X-ray diffraction analysis reveals a phase transition in Gd-Co codoped BiFeO3 ceramics when x is larger than 0.1.The current densities of all samples measured at room temperature are approximately three orders of magnitude lower than that of BFO ceramic, and the leakage current of the ceramics at room temperature exhibits two distinctive conduction behaviors: Ohmic conduction and space charge limited (SCL) conduction mechanism.For all the samples studied here, the dielectric constant and dielectric loss decrease with the increase of frequency in a range from 1 kHz to 1 MHz. The dielectric constants of Bi0.95Gd0.05Fe1-xCoxO3 (x= 0, 0.05, 0.1, 0.15,0.2) samples are nearly 1.9, 2.68, 3.85, 5.3, and 6 times larger than that of pure BiFeO3 (εr= 61.2) ceramic at 1 kHz, respectively. And the dielectric losses of Bi0.95Gd0.05Fe1-xCoxO3 samples become smaller than that of BFO ceramic.The magnetic measurements show that all the samples possess strong ferromagnetism at room temperature expect BiFeO3 and Bi0.95Gd0.05FeO3 which are weakly ferromagnetic. Under an external magnetic field of 30 kOe, the values of Mr of Bi0.95Gd0.05Fe1-xCoxO3 are 34, 60, 105, 103 and 180 times that of BiFeO3, respectively.
Influence of core-shell structure on dielectric behaviour in relaxor ferroelectrics
Authors: Shu Ming-Fei  , Shang Yu-Li  , Chen Wei  , Cao Wan-Qiang  ,   School of Materials Science and Engineering, Hubei University, Wuhan 430062, China
Published: December 2020

Dominant features of relaxor ferroelectrics are dielectric dispersion and the nonlinear relationship between reciprocal dielectric constant and temperature. The result of the analysis of the thermal dynamic function for core-shell structure in a grain shows that the core-shell structure doped with dopant in linear gradient descending ingredients can remain high dielectric constant at low temperatures, but cannot lead to the nonlinear relationship between reciprocal dielectric constant and temperature. By comparing diffusion transitions with different doping ingredients, it is suggested that the concentration of ingredient will affect the inhomogeneity of the doping ingredient. A wide distribution of the ingredient between grains by high doping concentration will result in the nonlinear relationship between reciprocal dielectric constant and temperature, and therefore the coexistence of grains in paraelectric phase and in ferroelectric phase in the peak area of dielectric constant. The change of measurement temperature will affect the ratio of the grains in two phases and the change in ferroelectric domains, which results in ferroelectric dielectric dispersion. The core-shell structure will increase the dielectric dispersion. Ferroelectric ceramics, doping species and their concentrations, and sintering temperature all can influence the inhomogeneity of core-shell structure and dielectric dispersion.
Efficiency droop in blue InGaN/GaN light emitting diodes on Si substrate
Authors: Liu Mu-Lin  , Min Qiu-Ying  , Ye Zhi-Qing  ,   School of Material Science and Engineering, Nanchang University, Nanchang 330031, China;,   College of Physics and Communication Electronics, Jiangxi Normal University, Nanchang 330022, China
Published: December 2020

InGaN/GaN based light emitting diodes (LEDs) suffer from decrease in efficiency at a high injection current level which is called efficiency droop. In this paper, blue InGaN/GaN multiple quantum well light emitting diodes on Si (111) substrates are prepared, and their electroluminescence spectra are tested. Comparing the experimental measurements with the simulating results based on simple ABC model, the cause for quantum efficiency droop is investigated. The results show that the light emitting diode has worse electron spreading and less hole concentration with temperature decreasing, and the electrons will overflow frome the well after filled up in higher and higher state for their inhomogeneous distribution, thus efficiency droop will happen at a lower injection more severely for electron leakage under lower injection, and experimental measurements are in disagreement with simulation results of Auger recombination at high injection current levels under different temperatures. The results confirm that the main factor for efficiency droop is not Auger nonradiative recombination but electron leakage, and the essential cause for electron leakage is severe carrier localization.
The investigation of performance improvement of GaN-based dual-wavelength light-emitting diodes with various thickness of quantum barriers
Authors: Chen Jun  , Fan Guang-Han  , Zhang Yun-Yan  ,   Experimental Teaching Center, Guangdong University of Technology, Guangzhou 510006, China;,   Institute of Opto-Electronic Materials and Technology, South China Normal University, Guangzhou 510631, China
Published: December 2020

The electrical and optical characteristics of GaN-based dual-wavelength light-emitting diodes (LEDs) with the specific design of various thick barriers are investigated numerically. The simulation results show that the thickness of barrier plays a regulatory role in emission spectrum of the dual-wavelength LED. The internal quantum efficiency droop is improved and the two peaks of spectrum become uniform due to the thickness of barriers gradually decreasing from the n-side to the p-side in a specific way. The balanced distribution of carrier concentration and the enhancement of electron confinement could be the major physical mechanism behind these improvements. It is also shown that the better optical performance is achieved at the large current injection level.
Magnetization of degenerate and relativistic electron gas
Authors: Wang Zhao-Jun  , Zhu Chun-Hua  , Huo Wen-Sheng  ,   School of Physics, Xinjiang University, Urumqi 830046, China
Published: December 2020

The dense electron gas interior neutron star is high degenerate and relativistic. The observation of neutron star about its thermal and magnetic effects depends on transport properties of the electron gas which is thought as the magnetic carrier. Its Landau levels in magnetic field are quantized and highly degenerate. The energy difference of an electron gas between in and not in magnetic field determines the magnetization of the gas, and the corresponding susceptipilities can be obtained through the thermodynamic calculation. When the magnetic field is weak, the susceptipility is 10-3 having similar order as in white dwarf. While in strong field the magnetization has the de Haas-van Alphen fluctuant effect like in microtherm metals. The differential susceptipilities can equal or exceed critical for high order harmonic frequency. Correspondingly, there is probably the phase-instability occuring in dense electron gas and the stable state is consisted of two different magnetization phases similar as the first-order phase transition of water. But if, there is a surface energy at the boundary then there is metastable state of homogeneous magnetization. The phase transition of interior neutron star can be observed through its electromagnetic radiation.This electromagnetic radiation may provide the extra energy in starquake model which was proposed to explain the giant flash of a magnetar.
Study on derivation and optimization algorithm about thin plate bending large deformation higher-order nonlinear partial differential equations
Authors: Hou Xiang-Lin  , Zheng Xi-Jian  , Zhang Liang  , Liu Tie-Lin  ,   School of Traffic and Mechanical Engineering, Shenyang Jianzhu University, Shenyang 110168, China;,   Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China;,   School of Civil Engineering, Shenyang Jianzhu University, Shenyang 110168, China
Published: December 2020

For a thin plate bending large deformation problem, variational principle is applied, and higher-order nonlinear partial differential equations about thin plate bending large deformation is established. Based on difference method and dynamic design variable optimization method, making unknown deflection of discrete coordinate points as design variables, differential equations sets of the discrete coordinates points as building objective function, a dynamic design variable optimization algorithm for computing thin plate bending deflection is proposed. Universal computing program is designed. Practical example about rectangular thin plate with fixed boundary under uniform load is analyzed. Comparing the program computing result with finite element solution. Effectiveness and feasibility of the method are verified. This method can be used to solve engineering problem.
Study on gradually-varying cavity for a gyrotron
Authors: Lei Chao-Jun  , Yu Sheng  , Li Hong-Fu  , Niu Xin-Jian  , Liu Ying-Hui  , Hou Shen-Yong  , Zhang Tian-Zhong  ,   Terahertz Science and Technology Research Center, University of Electronic Science and Technology of China, Chengdu 610054, China;,   The Chinese People's Armed Police Force Academy, Langfang 065000, China
Published: December 2020

The mode competition is the problem to be solved urgently in high-order mode gyrotron. Based on the generalized theory of transmission line, a group of first order transmission line equations that can accurately describe the coupling modes in a gradually-varying cavity is studied. Through analysing the expressions of the coupling coefficients between the various modes, a gradual-varying cavity for a gyrotron is designed. It is proved that the power in spurious modes in this novel cavity may be kept far below that in the line-joint cavity. The normalized amplitudes of non-operating modes can reach -100 dB in cavity and -88.6 dB in travelling wave guide.
Modified function projective lag synchronization for multi-scroll chaotic system with unknown disturbances
Authors: Liu Heng  , Yu Hai-Jun  , Xiang Wei  ,   Department of Mathematics and Computer Science, Huainan Normal University, Huainan 232038, China;,   Departement of Physics and Electronic Information, Huainan Normal University, Huainan 232038, China
Published: December 2020

In this paper, we treat the modified function projective lag synchronization between two non-identical multi-scroll chaotic systems with unknown disturbances. By utilizing the lyapunov stability theory, the fuzzy adaptive controller and parameter update law are derived to make the state of chaotic system achieve modified function projective lag synchronization. The controller can keep the systems stable even when the disturbance changes. Finally numerical simulations are performed to show the effectiveness of the proposed method.
Field programmable gate array-based chaotic encryption system design and hardware realization of cell phone short message
Authors: Pan Jing  , Qi Na  , Xue Bing-Bing  , Ding Qun  ,   Electronic Engineering College of Heilongjiang University, Key Laboratory of Electronic Engineering College of Heilongjiang Province, Harbin 150080, China
Published: December 2020

More and more people having cell phone, they must pay more attention to message security of their personal privacy, in which cell phone short message security is the most important. In this paper, we focus on designing an encryption hardware system of cell phone short message with chaos and A5/1 hybrid algorithm and realizes it on field programmable gate array. In the encrypted core, chaotic sequences of logistic map are used as initial keys of A5/1 algorithm for encrypting short messages, and in this paper we prove the relationship between linear correlation and circle correlation in the pseudo-randomness research of chaotic sequences serving as the initial keys. The SIM300 modules are used to realize cell phone functions, simulate short messages of common cell phone and the encrypte short messages after processing by our system by wireless transmitting through the base station. In addition, in this paper we design a software test platform, and it can show the results of this hardware system on computer. The test results indicate that the proposed system and its hardware implementation can encrypt/decrypt short messages and ensure their normal transmission, which can improve the security of short message and ensure its integrity and reliability during transmitting.
Strain effect on the intercalation potential of the layered Mn-contained lithium ion batteries cathode materials: a first principles method
Authors: Ren Xiao-Dong  , Liu Jian-Jun  , Zhang Wen-Qing  ,   State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, China
Published: December 2020

The strain effects on the intercalation potentials of LiMnO2 and Li2MnO3 are investigated by the first principles method, and the relationship between the intercalation potential and the strain is given in the form of elastic response. All the modes of strain reduce the intercalation potential and the effect is anisotropic. Most of the single modes reduce the potential by less than 0.1 V when the strains are 5%. The bonding between the host layers is rather sensitive to the strain perpendicular to the host layer when the lithium vacancy left by lithium extraction is in the lithium layer, thus that strain brings more reduction to the intercalation potential; whereas for the Li2MnO3 system when lithium is extracted form the transition metal layer, the strain along the host layer brings more reduction to the potential. For the Li2MnO3-stabilized LiMO2 (M=Mn, Ni, Co) solid solution system, the strain can keep the voltage of the high potential charging stage lower than the cut-off voltage, and open up the migrating pathway of lithium in the transition metal layer, therefore the charging can last a long time and larger charging capacity is achieved.
Spatial dispersion of pulse shaping system with high resolution based on the frequency comb
Authors: Wang Nan  , Han Hai-Nian  , Li De-Hua  , Wei Zhi-Yi  ,   Key Laboratory of Optical Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
Published: December 2020

High resolution pulse shaping based on the frequency comb has been widely used in microwave photonics, spectroscopy and communication optics and so on. To describe and evaluate the resolution capability of such a pulse shaping system, the ray tracing method is adopted to analyze the spatial dispersions of four schemes like single grating, parallel gratings, single grating with focus and anti-parallel gratings with focus. The spot spacings and sizes of different wavelengths can be determined from the modeling. As indicated by the calculation results, the latter two structures are advantageous to achieve high resolution pulse shaping; frequency combs with long wavelength, large mode spacing and big spot size are favorable for space dispersion; high grating groove density, small incident angle and multi passes in the dispersion system are conducible to the achievement of high resolution. The criterion for resolution would bring on some spot overlap noise.
Investigation on the characteristics of electromagnetic scattering from large-scale rough surface of layered medium
Authors: Zhang Yu  , Zhang Xiao-Juan  , Fang Guang-You  ,   Key Laboratory of Electromagnetic Radiation and Sensing Technology of CAS, The Institute of Electronic, Chinese Academy of Science, Beijing 100190, China;,   Graduated University of Chinese Academy of Science, Beijing 100190, China
Published: December 2020

A physical model for the electromagnetic scattering from large-scale rough surface of layered medium is established. Stratton-Chu integral equation and Kirchhoff approximation are adopted to calculate the electromagnetic scattering field. The Gaussian random rough surface is selected to simulate the actual rough surface of layered medium. The scattering echo is detected with a single-station nadir-looking radar sounder. The effects of surface and subsurface's roughness on the scattering filed are examined both theoretically and numerically. The effect of upper layer's electric properties (permittivity and conductivity) on the scattering field is also investigated and some analysis for the numerical results is presented.
A new multi-wavelength two-way quantum key distribution system with a single optical source
Authors: Yue Xiao-Lin  , Wang Jin-Dong  , Wei Zheng-Jun  , Guo Bang-Hong  , Liu Song-Hao  ,   Laboratory of Nanophotonic Functional Materials and Devices, School of Information and Photoelectronic Science and Engineering, South China Normal University, Guangzhou 510006, China;,   Laboratory of Quantum Information Technology, South China Normal University, Guangzhou 510006, China
Published: December 2020

Low-efficiency is an important issue in "plug and play" quantum key distribution system for practical application. The inefficient reasons of system and the current solutions are analyzed. And then a new quantum key distribution scheme with multi-wavelength pulses is proposed, in which a broadband optical source and the WDMs are combined to generate the optical pulses with four wavelengths. Moreover, the WDMs can also be used as a filter to extract the signal in the proposed scheme. Compared with other schemes, this scheme is highly stable, more securate and independent of the response speed of the control systems. The scheme can be used in high efficiency "plug and play" quantum key distribution system in practice.
Study of collimator array based on single collimating lens
Authors: Yuan Zhi-Lin  , Yang Rui  , Yang Liu  , Song Li-Dan  , Sun Li-Ping  , Ma Yu-Hong  , Wang Meng  , Chen Ding-Kang  , Guo Jin-Ping  , Tang Li-Hong  ,   State Key Laboratory of Optical Communication and Networks, Accelink Technology Co., Ltd., Wuhan 430074, China
Published: December 2020

A new collimator array based on single collimating lens and fiber array is proposed in the paper. An in-depth study is conducted on the two realizing methods, one is with glue in the optical path and the other is without glue in the optical path. Based on Gauss optics transmission matrix and q parameter theory, the relationship among the variables is deduced and computed theoretically, simulated virtually and confirmed experimentally. Good agreement between theoretical results and simulation, experimental results is obtained. The mechanical and packaging designs of the two realizing methods are first studied, then the proposed collimator arrays, with good performance are made. Both the theoretical and experimental results show that the scheme has the merits of easy-to-make, low cost, easy-to-package, good performance, good scalability, etc., which can strongly support the development of reconfigurable optical add-drop multiplexer system and optical cross-connect system.
The generation and transmission research of the fan-shaped multi-beam intense relativistic electron beams
Authors: Wu Tao  , Huang Hua  , Wang Gan-Ping  , Jin Xiao  , Liu Zhen-Bang  , Chen Zhao-Fu  , Ren Yi-Hao  , Chen Yong-Dong  , Wang Qing-Yuan  ,   School of Physical Electronic, University of Electronic Science and Technology of China, Chengdu 610054, China;,   High Power Microwave Laboratory, Institute of Applied Electronic, CAEP, Mianyang 621900, China
Published: December 2020

Compared with the beam of conventional relativistic klystron, each beam of the multi-beam relativistic klystron has a low perveance and low space charge force, but it has a high conversion efficiency of beam-wave. According to these requirements, in this paper we investigate the generation and transmission of fan-shaped multi-beam intense relativistic electron beams by the experiment and the simulation with using the three-dimensional software, and analyse the electrostatic field distribution of the cathode end and the influence on the generation of the electron beams by establishing a three-dimensional model of electron gun. The emission currents by the particle-in-cell simulation, then the beam spot pictures of electron beam transmission in a hollow drift tube and multiple fan-shaped hole drift tube by the particle tracking solver are obtained. The theoretical analysis and explanation with the aid of the sheet beam theory are presented. The simulation and experimental results show that the beams rotate not only around their own center, but also around the center of the system in the transmission process of the electron beams in the hollow drift tube. Thus we can increase the transmission efficiency by rotating multiple fan-shaped hole drift tube to align the beams.
Microscopic simulation on shock-induced micro-jet ejection from metal Al surface
Authors: Shao Jian-Li  , Wang Pei  , He An-Min  , Qin Cheng-Sen  ,   Institute of Applied Physics and Computational Mathematics, Beijing 100094, China
Published: December 2020

Via molecular dynamics simulations employing an embedded-atom-method potential, we investigate the microscopic process and dynamical properties of shock-induced micro-jet from a grooved aluminum surface. For a large range of shock pressure, we obtain the micro-jet morphology variation, its mass spatial distribution and mass-velocity distribution. The amorphous state and release melting during the jetting are both analyzed using the central symmetry parameter, where the effect law of release melting on the micro-jet is obtained. It is found that the micro-jet mass keeps a linear increase with the piston velocity prior to release melting; the micro-jet mass is enhanced evidently after release melting; while the velocity of release melting is above a threshold, the jetting mass shows a linear increase with the piston velocity again, where the strength of material can be neglected.
Research of coherence between driven-laser beams and its influence on backscatter
Authors: Meng Xiang-Fu  , Wang Chen  , An Hong-Hai  , Jia Guo  , Fang Zhi-Heng  , Zhou Hua-Zhen  , Sun Jin-Ren  , Wang Wei  , Fu Si-Zu  ,   Shanghai Institute of Laser Plasma, Shanghai 201800, China
Published: December 2020

Previous studies have shown that the technology of beam smoothing may effectively control parameter instabilities within the laser-plasma interaction, and greatly reduce stimulated Brillouin scattering (SBS) and stimulated Raman scattering (SRS). However, the recent experimental results on NIF revealed a much higher SBS and SRS than expected, one possible reason is due to the coherence between incident laser beams. In our research, two laser beams from Shenguang II facility are employed to irradiate an Au plate target, the energy and spectra of the backscattered light are measured in different coherent conditions. The results show that the driven-laser beams strongly interfere with each other, and usually the backscatter becomes strong gradually with the increase of coherent degree between the incident beams.
Electron-beam induced abnormal expansion in a silica-shelled gallium microball-nanotube structure (Retracted Article)
Authors: He Min-Hua  , Zhang Duan-Ming  , Gao Yi-Hua  ,   School of Science, Wuhan Institute of Technology, Wuhan 430073, China;,   School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
Published: December 2020

Under electron-beam irradiation of heteroshape-heteroscale structure of silica-shelled Ga microball-nanotube, an abnormally large and fast volume expansion of liquid Ga is observed. First, we analyze the processes and phenomena about experiment, and the abnormal expansion process can be regarded as a quasi-static process. Then in the framework of quasi-static thermodynamics, according to the Fourier heat conduction law the relative volume variation with temperature is further quantitatively discussed, and the relative expansion rate and expansion coefficient in system are obtained. At the same time it is found that abnormal expansion coefficient of system under electron-beam irradiation is 5-9 times the general thermal expansion coefficient. Finally, it is pointed out that the abnormal expansion is due to the gallium atom ionization effect and the retention effect resulting from a few electrons retaining in the liquid gallium system under electron-beam irradiation. In essence, both ionization effect and the retention effect make the particle densities of liquid systems increased dramatically, resulting in volume expansion abnormally large and fast of liquid Ga.
Improvement on performance of Si-based Ge PIN photodetector with Al/TaN electrode for n-type Ge contact
Authors: Wu Zheng  , Wang Chen  , Yan Guang-Ming  , Liu Guan-Zhou  , Li Cheng  , Huang Wei  , Lai Hong-Kai  , Chen Song-Yan  ,   Department of Physics, Semiconductor Photonics Research Center, Xiamen University, Xiamen 361005, China
Published: December 2020

Large contact resistance due to Fermi level pinning effect at the interface between metal and Ge strongly restricts the 3 dB bandwidth of Ge photodetectors. In this paper, the Ge PIN photodetectors fabricated on silicon-on-insulator substrates, respectively, with Al and Al/TaN electrodes are comparatively studied. It is found that 3 dB bandwidth of photodetector with 24 μm mesa diameter using an Al/TaN stack electrode is improved by four times more than that of the same structure Ge PIN photodetector using an Al electrode under -1 V bias at 1.55 μ. In addition, the dark current is reduced by one order of magnitude, and optical responsivity is enhanced by two times. These results suggest that a thin metallic TaN layer as an electrode can effectively passivate the Ge surface and alleviate the Fermi-level pinning effect, thus reducing the contact resistance and the recombination current at the interface. TaN can be considered as a promising electrode material for Ge device applications.
Relationship between liquid structure and property IIIresidual bond theoretical model
Authors: Mi Guang-Bao  , Li Pei-Jie  , Huang Xu  , Cao Chun-Xiao  ,   Aviation Key Laboratory of Science and Technology on Advanced Titanium Alloys, Beijing Institute of Aeronautical Materials, Beijing 100095, China;,   National Center of Novel Materials for International Research, Tsinghua University, Beijing 100084, China
Published: December 2020

Based on the concept of residual bond, a physical model quantitatively describing the relationship between the melt structure and viscosity of metal is established by mathematical deduction, and the microscopic nature of viscosity is considered to be the evolution of the size d of the residual-bond structure of melt. Using this model, the kinematic viscosityies of the magnesium and aluminum melt in a certain region above the melting point are calculated, and the functional relations vMg=3.1710-7+3.0410-7d and vAl=1.6510-7+1.0510-7d are obtained, which accord with the experimental data measured by the method of crucible rotating oscillation damping. This model reveals the microscopic naturs of the micro-inhomogeneity and viscosity of the melt structure from the view of chemical bond, which provides a new way to calculate the viscosity of melt and is of significance for understanding the relationship between microstructure and macroscopic properties of liquid metal.
Dielectric spectra of ZnO varistor ceramics
Authors: Cheng Peng-Fei  , Li Sheng-Tao  , Li Jian-Ying  ,   School of Science, Xi'an Polytechnic University, Xi'an 710048, China;,   State Key Laboratory of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, Xi'an 710049, China
Published: December 2020

In this paper, the dielectric spectra of ZnO varistor ceramics are measured by Novocontrol wide band dielectric spectrometer in a temperature range of -160℃-200℃ and frequency range of 0.1 Hz-0.1 MHz. It is found that electron transportation can be characterized by the flat region on a low frequency side of σ'-f curve. The Schottky barrier height is 0.77 eV obtained from σ'-f curve, which is consistent very well with the data from I-V curves given in other literature. On the basis of back-to-back double Schottky barrier model, Schottky barrier height corresponding to electron transportation across grainboundary is explained to be the energy difference between interface state and barrier top. According to this explanation, Schottky barrier height will increase linearly with the increase of DC voltage applied. The linear variation of barrier height with the increase of DC voltage applied is confirmed experimentally. Finally, the theoretical value of averaged grain size is obtained to be 6.8 μm, which is almost identical to 6.5 μm measured from SEM images. Therefore, the macroscopic electrical properties and the microstructure can be expressed at the same time by dielectric spectra.
Dynamic behaviors of domain wall in FM/AFM bilayers
Authors: Zhu Jin-Rong  , Xiang Mei  , Hu Jing-Guo  ,   College of Physics Science and Technology, Yangzhou University, Yangzhou 225002, China
Published: December 2020

The magnetic domain evolution behaviors of ferromagnetic (FM) monolayer and ferromagnetic (FM)/antiferromagnetic (AFM) bilayer are compared and analyzed. The results indicate that the equivalent width, mass and velocity of magnetic domain wall are changed, then the coercivity is enhanced and the exchange bias is present due to the exchange coupling between anti- ferromagnetic and ferromagnetic layer. The results also show that the equivalent width, mass and velocity of magnetic domain wall for FM /AFM bilayers system could be varied with the change of the net magnetization of antiferromagnetic layer, the magnetic anisotropy constants of FM and AFM layer, the exchange coupling constant of antiferromagnetic layer, interface exchange coupling constant and the temperature, and the relevant influences on the coercivity and exchange bias are discussed. So, the physical mechanisms of the emergence of exchange bias and enhancement of coercivity are discovered by the formation and evolution of the domain wall.