bluuebunny/crossref_metadata_2025 huggingface dataset:
Zero-index metamaterial based on double-negative structure
Authors: Su Yan-Yan  , Gong Bo-Yi  , Zhao Xiao-Peng  ,   School of Science, Northwestern Polytechnical University, Xi'an 710129, China
Published: December 2020

We present a new kind of zero-index metamaterial composed of periodic array of dendritic cells with continuous long pole, and investigate its electromagnetic characteristics. First, we study the one-level dendritic cell with continuous long pole. The retrieved effective permittivity and permeability of the unit cell simultaneously tend to be zero from their negative values at a frequency of 9.5 GHz, which leads to a near-zero refractive index. Then by changing the geometric parameters of the unit, we find the influences of the branch length and the separation angle on the electromagnetic parameters. Finally, increasing the level number of the branch gives rise to two-level and three-level dendritic cells respectively with continuous long pole. Adjusting the geometric parameters of each unit cell to appropriate values, the zero-index matematerials with zero permittivity and permeability can be obtained at the same frequency.
The ratio choice method of the pinhole aperture to the waist of the Gaussian laser in the fabrication of holographic gratings
Authors: Han Jian  , Bayanheshig  , Li Wen-Hao  ,   Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China;,   Graduate University of Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

In the fabrication of the holographic diffraction gratings, the scatter light which is produced by the reflection of the granule in air or the diffraction defect of the optical apparatus will be recorded simultaneously in the resist. Those noises not only reduce the diffraction efficiency of gratings, but also give rise to the scattered light in diffraction. So an appropriate spatial filter should be used to stop the higher spatial frequencies corresponding to the Gaussian beam. Because the diffraction effect after the pinhole aperture can demolish the wavefronts of laser, it is the most important to choose the optimal pinhole for adjusting the waist of the laser. On the basis of standard scalar diffraction theory, the field amplitude is given by the convolution calculation, the phase distortion of diffraction wavefronts is also analyzed, and the lower limit ratio of the aperture size with respect to the beam radius is given when the phase transitions are further away from the center. Using the energy conservation of Gaussian beam and comparing the characteristics change of diffraction beam, the effect of diffraction is presented and the upper limit ratio of the spatial filter is given by the critical condition of the diffraction. The conclusion shows that if the ratio of the aperture radius to beam waist is between 1.52 a/02.2, the phase is invariable in the area of the exposal, and the power transmitting the spatial-filter pinhole aperture is slightly more than 99%, so spatial filter performs its function only in this range of the radio.
An image hiding and blind extraction algorithm based on block discrete wavelet transform
Authors: Gan Tian  , Feng Shao-Tong  , Nie Shou-Ping  , Zhu Zhu-Qing  ,   Key Laboratory for Opto-electronic Technology of Jiangsu Province, Nanjing Normal University, Nanjing 210097, China
Published: December 2020

In this paper, we propose a blind watermarking algorithm based on block discrete wavelet transform. The watermark is scrambled by Arnold and two pseudo random sequences are generated first, and then according to the wavelet tree structure, the significant wavelet coefficients in a block are found and quantized by pseudo random sequence. During the extraction, the quantized coefficients can be found without the original image, then the correlation between them and the pseudo random sequences are calculated to estimate the watermark bits. Moreover, in this method all high-frequency subimages are used to provide better robustness. The performance of the proposed watermarking is robust to several attacks, especially quite effective against image cropping attack.
Near-field modulation of lateral cracks
Authors: Zhang Chun-Lai  , Wang Zhi-Guo  , Liu Chun-Ming  , Xiang Xia  , Yuan Xiao-Dong  , He Shao-Bo  , Li Li  , Zu Xiao-Tao  ,   School of Physical Electronics, 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

Light intensification caused by cracks in fused silica subsurface is one of main factors of laser-induced damage to optical materials. Three-dimensional finite-difference time-domain method is used to simulate parabola-section-model lateral cracks. Moreover, the relationship between light intensification and breadth-to-depth ratioR is discussed. The results show that the morphology change after acid etching is an important cause of damage mitigation. Modulation is very weak and close to each other whenR is greater than 10.0 and it increases rapidly whenR less than 5.0. The electric field intensity reaches a maximal value whenR ranges from 1.0 to 3.0, and the maximal electric field is 4.3 V/m. The electric field intensity of more than 80% samples exceed 2 times than the incident light whenR ranges from 1.0 to 3.5. Intensified area has the skin effect with depth increasing. It is demonstrated that enhanced area lying directly below the crack firstly shifts to left and right sides, then it moves to parabola-section interface and the horizontal interface. Finally, the whole subsurface will be enhanced. In addition, electric field modulation firstly increases and then decreases in the z direction when depth is large enough.
Theoretical and experimental investigations of spatial optical dark soliton filamentization in nonlocal self-defocusing Kerr medium
Authors: Wang Jing  , Zheng Yi-Zhou  , Zhou Luo-Hong  , Yang Zhen-Jun  , Lu Da-Quan  , Guo Qi  , Hu Wei  ,   School of Information and Optoelectronic Science and Engineering, South China Normal University, Guangzhou 510006, China
Published: December 2020

In this paper, the spatial optical dark soliton filamentization in a nonlocal self-defocusing Kerr medium is investigated. Theoretically, starting from nonlocal nonlinear theoretical model, we examine the influences of the degree of nonlocality and the attenuation constant on the formation of dark soliton filaments by numerical simulation method. We find that when the input background optical intensity is determined, the greater the degree of nonlocality, the farther the initial point of the formation of dark filaments is and the less the number of dark filaments decreases with the increase of the degree of nonlocality; when the ratio of the background optical intensity to the critical optical intensity is fixed, the degree of nonlocality can hardly influence the number of dark filaments and the number of dark filaments under nonlocality is equal to that under locality. Besides, when the input background optical intensity is determined, the number of dark filaments decreases with the increase of the attenuation constant. Experimentally, by changing the concentration of dye solution and the ellipticity of background light, we discuss the influences of the concentration of sample and the ellipticity of background light on the formation of dark soliton filaments respectively and find that when the input background average optical intensity is determined, the number of dark filaments decreases with the increases of the concentration of sample and the ellipticity of background light; when the ratio of the background average optical intensity to the critical optical intensity is fixed, the concentration of sample can hardly influence the number of dark filaments. Besides, the phenomenon of optical shock wave is found in our experiment.
A screw dislocation interacting with a wedge-shaped crack in one-dimensional hexagonal quasicrystals
Authors: Li Lian-He  , Liu Guan-Ting  ,   College of Mathematical Science, Inner Mongolia Normal University, Huhhot 010022, China
Published: December 2020

The interaction between a screw dislocation and a semi-infinite wedge-shaped crack in one-dimensional hexagonal quasicrystal is investigated by the conformal transformation method and the perturbation technique. Analytical solutions are obtained for the stress intensity factor of crack, and the force on dislocation. The effects of the dislocation location and the wedge angle on the image force of the dislocation are revealed. At the same time the influence of the dislocation on crack behaviour is also discussed in detail. The corresponding results of the sharp crack can be obtained as a special case of the present solutions (i.e. =1/2).
The effect of the interdot Coulomb interaction on Kondo resonance in series-coupled double quantum dots
Authors: Wu Shao-Quan  , Chen Jia-Feng  , Zhao Guo-Ping  ,   College of Physics and Electronic Engineering, Sichuan Normal University, Chengdu 610068, China
Published: December 2020

We theoretically investigate the effect of the interdot coulomb interaction on Kondo resonance in series-coupled double quantum dots. The Anderson Hamiltonian of our system is solved by means of the slave-boson mean-field approximation, and the variations of the density of states, the transmission probability, the occupation number and the Kondo temperature with interdot Coulomb interaction are discussed in the Kondo regime, and the densities of states are calculated in the Kondo regime for various interdot Coulomb repulsions with parallel and antiparallel lead-polarization alignments. Our results reveal that the interdot Coulomb interaction between quantum dots greatly influences the physical property of this system, and relevant underlying physics of this problem is discussed.
The influence of variable quantity of polarization on the current intensity of the electron emission from La-doped Pb(Zr, Sn, Ti)O3 ferroelectric cathode
Authors: Huang Xu-Dong  , Feng Yu-Jun  , Tang Shuai  ,   Key Laboratory of Electronic Ceramics and Devices of Ministry of Education, Xi'an Jiaotong University, Xi'an 710049, China
Published: December 2020

Ferroelectric cathodes exhibit huge potentials in high-power microwave tube electron beam source, panel display, and the propeller space navigation, due to their superior properties. The material properties of the ferroelectric cathode have been proved to have a significant influence on electron emission, which is indicated in recent research work. In the course of electron emission, the variation of polarization can be caused by non-shielded surface charge which is induced by high trigger voltage. A certain relationship may be found between polarization variation and current intensity of electron emission. To study the relationship between current intensity of electron emission and polarization variation in ferroelectric cathodes, the samples of lanthanum-doped lead zirconate stannate titanate ferroelectric and antiferroelectric ceramics are prepared by the method of solid state calcinations, and the polarization variations of the material under different voltages are measured in the positive half cycle test of hysteresis loop. The curve of the electron emission current intensity versus the trigger voltage is measured, and then the relationship between electron emission current intensity and polarization variation is investigated. The results show that the electron emission current intensities of the two samples are both directly proportional to the polarization variation.
Top-emitting white organic light-emitting diodes based on a ZnS light outcoupling layer
Authors: Chen Shu-Fen  , Shao Ming  , Guo Xu  , Qian Yan  , Shi Nai-En  , Xie Ling-Hai  , Yang Yang  , Huang Wei  ,   Key Laboratory for Organic Electronics and Information Displays of Jiangsu Province, Institute of Advanced Materials, Nanjing University of Posts and Telecommunications, Nanjing 210046, China
Published: December 2020

Top-emitting white organic light-emitting diode (TEWOLED) has potential applications in lighting and full color displays. Microcavity effect in TEWOLED restrains the realization of the white emission with excellent optical and electric performances. In this paper, a ZnS film with a high refractive index used as a light outcoupling layer is introduced into the metal cathode to enhance its transmittivity to a maximal value in the blue light wavelength region. In addition, transfer matrix theory is utilized to optimize the thicknesses of the cathode and the ZnS outcoupling layer and the wide-angle interference is used to design the position of the blue emission layer inside the organic light-emitting diode. Based on the above work, the white light with relatively high luminous efficiency, good color purity, and small CIE coordinate change is acquired. The corresponding luminance and current efficicency are 9213 cd/m2 and 3 cd/A, respectively. The CIE coordinates belong to the white emission and are near the white light equal-energy point. The white emission also shows stable spectra with respect to the observation angle, with a limited CIE coordinate change of (0.02, 0) for a large observation angle change from 0 to 60.
Spatiotemporal chaos anti-synchronization of a complex network with different nodes
Authors: LÜ Ling  , Liu Shuang  , Zhang Xin  , Zhu Jia-Bo  , Shen Na  , Shang Jin-Yu  ,   College of Physics and Electronic Technology, Liaoning Normal University, Dalian 116029, China
Published: December 2020

Anti-synchronization of complex network is investigated in which nodes are discrete spatiotemporal chaos systems with diverse structures. The form of the coupling functions connecting nodes in the complex network and the control gain are obtained through constructing an appropriate Lyapunov function. The spatially extended system of laser phase conjugate wave having spatiotemporal chaos behavior in physics, Gibbs electrical-optical spatiotemporal chaos model, Bragg acousto-optical spatiotemporal chaos model and the one-dimensional discrete convective equation are all taken as nodes of the complex network. Artificial results show that a stable anti-synchronization is obtained in the whole network.
Research of fluorescent properties of photo-induced electron transfer of 5(6)-carboxyfluorescein dye-sensitized TiO2 nanoparticles
Authors: Jiang Li-Lin  , Song Yun-Fei  , Liu Wei-Long  , Yu Guo-Yang  , He Xing  , Wang Yang  , Wu Hong-Lin  , Yang Yan-Qiang  ,   Centre for the Condensed Matter Science and Technology, Department of Physics, Harbin Institute of Technology, Harbin 150001, China;,   Department of Physics and Electronics Information Engineering, Hezhou University, Hezhou 542800, China
Published: December 2020

Anatased TiO2 nanoparticles were prepared by controlling hydrolysis of the TiCl4. Time-resolved fluorescence experiments were carried out to study the photo-induced electron transfer dynamics in the system of the 5(6)CFL dye-sensitized TiO2 nanoparticles. For the aboved system, the formation of the charge transfer complex is attributed to the coupling interaction between the wave functions of the excited electronic state of the dye ((D*)) and the charge separated state ((D++e-)). On excitation of 5(6)CFL dye-sensitized TiO2 nanoparticle system. The injection of electrons into the conduction band of TiO2 nanoparticles takes place in two different ways: through the excited state of the 5(6)CFL dye and through direct injection from the charge transfer complex. The time-resolved fluorescence experimental results indicate that the free 5(6)CFL dye in water has double-exponential decay with lifetimes1=41 ps (74.4%) and2=3.22 ns (25.6%). However, 5(6)CFL dye-sensitized TiO2 nanoparticles have triple-exponential decay with lifetimes of1=44 ps (90.4%),2=478 ps (8.6%) and3=2.41 ns (1.0%). Our research will provide a valuable reference for the mechanism of dye-sensitized solar cell.
The reasearch of spatiotemporally mixed modulated polarization interference imaging spectrometer
Authors: Zhu Bao-Hui  , Zhang Chun-Min  , Jian Xiao-Hua  , Zeng Wen-Feng  ,   MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, School of Science, Xi'an Jiaotong University, Xi'an 710049, China;,   Ordnance N.C.O Academy of PLA, Wuhan 430075, China
Published: December 2020

Spatiotemporally modulated polarization interference imaging spectrometer(TSMPIIS)is static, miniature, stable instrument for remote sensing polarization detecting, which can be used to obtain the spectral and the polarized information about the target. It has been approved that TSMPIIS can obtain the target information by circumrotating its polarizer. However this method destroys the structure of TSMPIIS and reduces the measurement accuracy. According to the detecting theory of TSMPIIS, in this paper, we derive the basic equations for TSMPIIS detecting by analyzing and calculating its Mueller matrix, and authenticate the feasibility and the veracity of TSMPIIS for polarization detecting in full field of view. This work is very helpful for TSMPIIS remote sensing detecting and the retrieval of Stokes parameters.
Slowdown of group velocity of light pulse in erbium-doped optical fiber amplifier under no absorption loss at a room temperature
Authors: Qiu Wei  , Ma Ying-Chi  , Lü Pin  , Liu Dian  , Xu Xiao-Juan  , Zhang Cheng-Hua  ,   Department of Physics, Liaoning University, Shenyang 110036, China
Published: December 2020

Because of the absorption of erbium-doped optical fiber, the group velocity of the optical pulse propagation is slowed down and the intensity of signal is reduced, which brings more difficulties to the actual measurement of slow light and its application in communications, such as the distortion and the low measurement.Therefore only after the group velocity slowdown of light pulse in erbium-doped optical fiber under no absorption loss is realized, can the slow light technology really have the practical application. We investigate the erbium-doped optical fiber amplifier deeply and develop a technology, in which the different pump powers and fiber lengths are used to reduce the signal loss through theoretical calculation and realize the group velocity slowdown of light pulse. The results show that no absorption loss is realized at a pump power of 3.5 mW, and we realize the slow light with a fiber length of 0.1 m when the pump power is zero.
Optical generation of high-quality millimeter-wave based on an optically injected VCSEL subject to polarization-rotated external optical feedback
Authors: Chen Xing-Hua  , Lin Xiao-Dong  , Wu Zheng-Mao  , Fan Li  , Cao Ti  , Xia Guang-Qiong  ,   College of Physical Science and Technology, Southwest University, Chongqing 400715, China;,   State Key Lab of Millimeter Waves, Southeast University, Nanjing 210096, China
Published: December 2020

A scheme of optical generation of high-quality millimeter-wave based on the optically injected vertical-cavity- surface-emitting laser (VCSEL) subject to polarization-rotated optical feedback is proposed in this paper. Based on the spin-flip model (SFM), wich external disturbances taken into account, the performances of the millimeter-wave generated by this scheme are numerically investigated. The results show that under suitable operation conditions, a slave VCSEL (S-VCSEL) injected by a master VCSEL (M-VCSEL) will operate in a period-one (P1) oscillation state and the output optical intensity of S-VCSEL looks like being modulated by a microwave signal. By adjusting the injection strength iand the frequency detuning between S-VCSEL and M-VCSEL, a millimeter-wave, whose frequency can be continuously adjusted in a large range from 30 GHz to 60 GHz, is obtained. After introducing polarization-rotated optical feedback, the linewidth of millimeter-wave can be obviously narrowed by adjusting the feedback strength i and the feedback delay time . For a millimeter-wave with a linewidth of 5.509 MHz, generated by the optically injected VCSEL, its linewidth can be reduced to 230.2 kHz under optimum feedback parameters. The results obtained in this paper are helpful for acquiring high-quality millimeter-wave used in high speed Radio-over-Fiber (RoF) system.
Experimental research and application of pulse clean technique based on cross polarized wave generation
Authors: Wang Jian-Zhou  , Huang Yan-Sui  , Xu Yi  , Li Yan-Yan  , Lu Xiao-Ming  , Leng Yu-Xin  ,   State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China
Published: December 2020

Cross polarized wave (XPW) generation technique is used to improve the contrast of the output pulses from a 800 nm Ti: sapphire femtosecond (fs) laser. The measured temporal contrast of the cleaned pulse is 1011 (limited by the dynamic range of the third-order auto-correlator), which is 3 orders of magnitude higher than the temporal contrast ratio of the initial pulse. The efficiency of XPW is 22%. And the bandwidth of the cleaned pulse is broadened after the XPW nonlinear process. Through the dispersion compensation using double chirped mirrors and fused silica plate, the 25 fs pulse duration is achieved. With the cleaned pulse used as the seed of a TW-level Ti: sapphire chirped-pulse amplification laser system, the 250 mJ/50 fs pulses corresponding to 5 TW peak power are obtained. And the 1011 temporal contrast is demonstrated on the time scale of hundreds of picoseconds before the main femtosecond pulse.
Control of the thermal lensing effect in solid-state laser
Authors: He Guang-Yuan  , Guo Jing  , Jiao Zhong-Xing  , Wang Biao  ,   State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275, China
Published: December 2020

The thermal lensing effect of solid-state lasers under the lasing condition is studied by a thermal model for designing a working cavity. We simulate variations of the stable zones for cavities with different configurations. Theoretical descriptions are verified by a Nd: YAG laser in the experiment. The control of the thermal lensing is achieved experimentally by changing the configuration of the cavity.
Molecular dynamic of selectivity and permeation based on deformed carbon nanotube
Authors: Xu Kui  , Wang Qing-Song  , Tan Bin  , Chen Ming-Xuan  , Miao Ling  , Jiang Jian-Jun  ,   Department of Electronic Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, China
Published: December 2020

Extensive molecular dynamics simulations of water permeation and ion selectivity of the single-walled carbon nanotubes with the radial deformation are presented. The simulated results indicate that there is a close relationship between the minor axis of deformed carbon nanotubes and the variety, density as well as the position of functional groups. The critical minor axis of different diameter carbon nanotubes exists, and the carbon nanotube whose minor axis is less than the critical minor axis owns the selectivity of chlorine and sodium ions. Meanwhile, compared with intrinsic carbon nanotubes, the deformed nanotubes do not obviously reduce the permeation of water. The analysis of the potential of mean force reveals that the selectivity and the permeation of ions come from the pass potential barrier of carbon nanotubes with various minor axises. Furthermore, our observations of modifying functional groups may have significance for controlling the minor axis and improving the selectivity and permeation of ions in real manufacture of some large nanotubes.
NPN bipolar effect and its influence on charge sharing in a tripe well CMOS technology with n+ deep well
Authors: Liu Bi-Wei  , Chen Jian-Jun  , Chen Shu-Ming  , Chi Ya-Qin  ,   Computer School, National University of Defense Technology, Changsha 410073, China
Published: December 2020

In this paper, we investigate the charge sharing collection induced by heavy ion radiation in a tripe well CMOS technology with n+ deep well though 3-D TCAD device simulation. Result shows that n+ deep well will induce the parasitical NPN bipolar transistor, and therefore enhance the charge sharing between NMOS remarkably. The enhancement factor is 24 times that in PNP bipolar in dual well technology. Furthermore, the effects of n-well contact and p-well contact on NPN bipolar are studied. The result shows that the NPN bipolar enhancement factor will decrease with the increase of p-well contact area and with the decreasing of its distance to device, while the NPN bipolar enhancement factor will increase with the increase of n-well contact area.
Phase transition and properties of siderite FeCO3 under high pressure: an ab initio study
Authors: Ming Xing  , Wang Xiao-Lan  , Du Fei  , Chen Gang  , Wang Chun-Zhong  , Yin Jian-Wu  ,   College of Physical Science and Technology, Huanggang Normal University, Huanggang 438000, China;,   College of Physics/State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012, China
Published: December 2020

The crystal structure, electronic configuration and electronic structure of siderite FeCO3 are studied by first-principles calculations through the plane wave pseudo-potential method. The real antiferromagnetic (AFM) spin ordering state is considered. The pressure increases up to 500 GPa under hydrostatic pressure condition. FeCO3 transforms from high spin (HS) AFM state to low spin (LS) nonmagnetic (NM) state in a pressure range between 40 and 50 GPa, accompaned with a volume collapse of 10.5%. Siderite FeCO3 is insulating before and after the phase transition, but the 3d electrons of Fe2+ ions for the LS-NM state are more localized, The band gap increases with pressure increasing, and the LS-NM state moves into a more strong ionic state and no metal-insulator transition (MIT) occurs.
Measurement of industrial gas pollutant emissions using differential optical absorption spectroscopy
Authors: Sun You-Wen  , Liu Wen-Qing  , Xie Pin-Hua  , Fang Wu  , Zeng Yi  , Si Fu-Qi  , Li Xian-Xin  , Zhan Kai  ,   Key Laboratory of Environmental Optics and Technology, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China
Published: December 2020

In this paper, we present a method of measuring the industrial gas pollutant emissions concentration by using differential optical absorption spectroscopy (DOAS). The dust and water vapor which affect the spectrum fitting are filtered by the sample and pretreatment system. In order to avoid the photolysis of SO2 with high concentration, the pretreated smoke mixtures are heated to 150 ℃. In the process of DOAS retrieval, the reference absorption cross sections (185–235 nm) of SO2, NO and NO2 at high temperature are calculated by applying the Voigt broadening method to the original absorption cross sections at low temperature. The influences of temperature, pressure and instrument function are taken into account in the calculation. A validation study of SO2 and NO measurement is performed by comparing with the results measured by a non-dispersive infrared analyzer. The result shows that they are in good agreement with each other indicating that the DOAS technique has a potential application to industrial gas pollutant emissions measurement.
Observation of the avoided crossing of Cs Rydberg Stark states
Authors: Wang Li-Mei  , Zhang Hao  , Li Chang-Yong  , Zhao Jian-Ming  , Jia Suo-Tang  ,   State Key Laboratory of Quantum Optics and Quantum Optics Devices, Laser Spectroscopy Laboratory, Shanxi University, Taiyuan 030006, China
Published: December 2020

The Stark effect of ultra-cold Cs Rydberg atom is investigated in a magneto-optical trap, and the avoided crossing between nS state and (n-4) manifold is observed. The ion spectrum near the avoided crossing is obtained by using state-selective field pulse ionization technique. By changing the intensity of the applied electric field, we find that the relative intensities of two Stark states near the avoided crossing exchange obviously. Furthermore, state transfer from nS Rydberg state to high-l state due to the avoided crossing is also obtained.
Accurate calculation of elastic scattering properties of ultracold sodium atoms
Authors: Zhang Ji-Cai  , Zhu Zun-Lüe  , Sun Jin-Feng  ,   College of Physics and Information Engineering, Henan Normal University, Xinxiang 453007, China;,   Department of Physics, Luoyang Normal College, Luoyang 471022, China
Published: December 2020

Based on the accurate singlet and triplet state interatomic potentials for Na2, a theoretical study of elastic scattering properties of sodium atoms at ultracold temperatures is reported in this paper. The s-wave scattering length, effective range, the p-wave scattering length and the number of bound states are calculated. The singlet and triplet elastic scattering cross section between sodium aotms at ultracold temperatures are dominated by s-wave scattering, and shape resonances occur with collision energy increasing. There exist pronounced f-wave and i-wave shape resonances for the singlet and triplet cross section. In addition, s-wave scattering length is calculated by using the degenerate internet state approximation for selected hyperfine states of sodium atoms. The results are in agreement with calculated values obtained by close-coupling method.
Numerical comparison between Ta and Nanbu models of Coulomb collisions
Authors: Wang Hui-Hui  , Yang Chao  , Liu Da-Gang  , Meng Lin  , Liu La-Qun  , Xia Meng-Zhong  ,   School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054, China
Published: December 2020

Two models (Ta and Nanbu) of Coulomb collisions are compared theoretically, and the difference in scatter angle between Ta model and Nanbu model is analyzed particularly. The model of Coulomb collisions between electrons in the code which is developed already with Ta model is rebuilded with Nanbu model. Then, the codes with Ta model and Nanbu model are used for simulating electron energy distribution in JAEA 10 A respectively. The results of simulation are compared with the experimental results, showing that the electron energy distribution is closer to Maxwell distribution with Coulomb collisions and the Nanbu model is more accurate than the Ta model.
Photoluminescence of macroporous-alumina prepared by polyacrylamide gel technique
Authors: Gao Xiao-Lin  , Wang Shi-Fa  , Xiang Xia  , Liu Chun-Ming  , Zu Xiao-Tao  ,   Department of Applied Physics, University of Electronic Science and Technology of China, Chengdu 610054, China
Published: December 2020

Macroporous -Al2O3 is synthesized by polyacrylamide gel technique. X-ray diffractor combined with a photoluminescence spectrophotometer is used to investigate the formation of Al2O3 phase and the light emission properties of xerogel sintered at different temperatures. It is demonstrated that high-purity -Al2O3 can be obtained at a sintering temperature of 1150 ℃. Scanning electron microscopy images reveal that the synthesized -Al2O3 has a monolithic structure. Photoluminescence spectra show that a major emission band around 365 nm and a weaker side band around 330 nm are observed when the excitation wavelength is 228 nm. The pore-formation and luminescence mechanisms of porous alumina are discussed based on the experimental results.
First-principles calculations of microstructure and thermodynamic properties of the intermetallic compound in Ag-Mg-Zn alloy under high pressure and high temperature
Authors: Lu Zhi-Wen  , Zhong Zhi-Guo  , Liu Ke-Tao  , Song Hai-Zhen  , Li Gen-Quan  ,   Institute of Advanced Materials, Nanyang Normal University, Nanyang 473061, China
Published: December 2020

The structural stability, elastic and thermodynamic properties of the intermetallic compounds MgAg, Mg4Zn8 and Ag8Mg4Zn4 in Ag-Mg-Zn alloy under high pressure and high temperature are investigated by employing the first-principles method based on the density functional theory. The theoretical results are generally in good agreement with experimental results and similar to the theoretical calculations. The calculated results indicate that the intermetallic compounds AgMg, Mg4Zn8 and Ag8Mg4Zn4 are elastically stable at zero temperature and pressure. Mg4Zn8 and Ag8Mg4Zn4 are of the ductility phase, and AgMg is of the brittleness phase. The plasticity of Ag8Mg4Zn4 is the best in the three intermetallic compounds, and AgMg is the worst. Based on the quasi-harmonic Debye model the vibrational internal energy, vibrational Helmholtz free energy, vibrational entropy, heat capacity of constant volume, heat capacity at constant pressure, thermal expansion coefficient Grneisen parameter and Debye temperature of the intermetallic compounds in Ag-Mg-Zn alloy under high pressure and high temperature are all discussed.
Shock-induced transformation behavior in NiTi shape memory alloy
Authors: Liu Hong-Tao  , Sun Guang-Ai  , Wang Yan-Dong  , Chen Bo  , Wang Xiao-Lin  ,   Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang 110819, China;,   Key Laboratory for Neutron Physics of Chinese Academy of Engineering Physics, Institute of Nuclear Physics and Chemistry, Mianyang 621900, China
Published: December 2020

The high-strain dynamic behavior of NiTi shape memory alloy has significant applications in several fields such as military af- fairs, aerospace. In order to investigate the transformation behavior in NiTi alloy, induced by dynamic mechanics, the shock-loading experiments are performed using a single stage gas gun at different temperatures and different shock velocities. Differential scanning calorimeter (DSC) and comprehensive physical property measurement system are employed to analyze the phase transformation in- duced by residual effects of shock waves in NiTi alloy. Three endotherms are observed in the first heating cycle, showing the presence of three-step reverse phase transformation; whereas during the second heating only one endotherm is seen, because the other two en- dotherms attributed to stress-induced martensite have disappeared. The exothermic and endothermic peak, owing to the transformation of shock-treated specimens, become small and their transformation temperature regions are broadened. This tendency indicates that the internal defects in the specimens, introduced by shock-treated, increase the resistance of phase transformation. The exothermic peaks of specimens, shock-treated at low velocity and high velocity, all shift to the low-temperature-zone, because the dislocations increase the hindrance to martensitic transformation. However, the endothermic peaks of specimens with low velocity shock-treated shift to high-temperature-zone, illustrating that the reverse martensitic transformation is also opposed by dislocations; while the endothermic peaks shift to low-temperature-zone for high velocity shock-treated, due to the decrease of transformation energy, caused by the re-duction of recoverable martensite. A small shoulder is detected in exothermic peak, whose shape becomes sharper with shock rate increasing. This result reveals that the intermediate phase (R-phase) results in two-stage phase transformation. The electrical resistivity measurement result further confirms that the two types of phase transformations associated with austenite to rhombohedral (A→R) and rhombohedral to martensite (R→M) can occur at the same time in a certain temperature range.
Performance of closed-loop control of epileptiform spikes in neural mass models
Authors: Liu Xian  , Ma Bai-Wang  , Liu Hui-Jun  ,   Institute of Electrical Engineering, Yanshan University, Qinhuangdao 066004, China
Published: December 2020

Neural mass models can produce electroencephalography (EEG) like signals corresponding to interical, pre-ictal and ictal activities. In this paper, a novel closed-loop feedback control strategy based on algebraic estimation is proposed to eliminate epileptiform spikes in neural mass models. Algebraic estimation plays a role in observing the states of the model in order to construct the controller. For a network of coupled neural populations, the characteristics regarding the closed-loop feedback control strategy, including the relationship between the type of controlled populations and the ability of eliminating epileptiform spikes, the relationship between the number of controlled populations and control energy, the relationship between the model parameters and control energy, are determined by numerical simulations. The purpose is to establish the rules for the proper control of eliminating epileptiform spikes with as less control energy as possible. Moreover, the proposed control-loop control strategy is compared with a direct proportional feedback control strategy by numerical simulations. It is shown that the use of algebraic estimation makes a reduction of control energy.
Chaos analysis of the conic in planar unit area
Authors: Yu Wan-Bo  , Yang Ling-Zhi  ,   School of Information, Dalian University, Dalian 116622, China
Published: December 2020

In the paper, the chaotic characteristic of the quadratic function in plane unit area is studied, and it is found that the standard quadratic mapping is Li-Yorke chaos, and also Devaney chaos, and that under certain conditions, there are a large number of quadratic functions that are chaotic. Some quadratic functions can transform into the standard quadratic functions by moving and zooming, without changing their chaotic characteristics. In addition, non-standard quadratic function is preliminary studied. The chaotic characteristic of the quadratic curve is analyzed by calculating Lyapunov exponents and drawing the bifurcation diagram of conic. The bifurcation diagram of the parameter variation and the area distributing diagram of parameter control points have certain research value. The study also shows that more conic curve cross iteration can generate a better chaotic sequence, and the chaotic sequence can be used to image encryption and other practical purposes.
The oscillation and bifurcation of a switching system composed of jump circuits
Authors: Gao Chao  , Bi Qin-Sheng  , Zhang Zheng-Di  ,   Faculty of Science, Jiangsu University, Zhenjiang 212013, China
Published: December 2020

The complex dynamical evolution of a circuit system composed of two nonlinear circuit subsystems, which is switched by a periodic switching, is investigated. According to the fact that the magnification of an open-loop operational amplifier is maximum magnification, namely, the operational amplifier is always in a positive or negative saturated state, when an input voltage becomes positive from negative through zero, the output voltage jumps from the positive saturation into negative saturation. In this paper the jump function is selected as a nonlinear part in subsystems. Firstly through the stability analysis of the subsystems, their oscillation behaviors in the parameter space are given correspondingly. Secondly the complex oscillation behavior and mechanism of the switched system are discussed in the parameter space of one subsystem. The periodic orbit of the switched system is divided into four parts, influenced by non-smooth characteristics of the subsystems and switching. With the variation of the parameters, grazing bifurcation appears, and then the whole periodic orbit is separated into two symmetrical periodic oscillations. Finally the convesion of switching points into the periodic oscillation is given,and the mechanism at switching point is discussed.
A family of four-dimensional multi-wing chaotic system and its circuit implementation
Authors: Luo Ming-Wei  , Luo Xiao-Hua  , Li Hua-Qing  ,   College of Automation, Chongqing University of Posts and Telecommunications, Chongqing 400065, China;,   College of Optoelectronic Engineering, Chongqing University of Posts and Telecommunications, Chongqing 400065, China;,   College of Computer Science, Chongqing University, Chongqing 400044, China
Published: December 2020

A new method to generate multi-wing butterfly chaotic attractors is presented. Based on the three-dimensional Lorenz system, in this paper we propose a four-dimensional multi-wing chaotic system by appending a state variable and a piecewise linear function. The equilibrium points and Lyapunov exponent spectra of the system are studied. Furthermore, an electronic circuit is designed to implement the system. The experimental results are in agreement with numerical simulation results, which verify the feasibility and availability of this method.
Theoretical study on polarities and spectrum properties of WnNim (n+m=8) clusters
Authors: Zhang Xiu-Rong  , Li Yang  , Yin Lin  , Wang Yang-Yang  ,   School of Mathematics and Physics, Jiangsu University of Science and Technology, Zhenjiang 212003, China;,   School of Materials Science and Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003, China
Published: December 2020

The possible equilibrium geometries of WnNim (n+m=8) clusters are optimized by using the density functional theory at the B3LYP/LANL2DZ level. For the ground state structures, the dipole moment, polarizability and vibrational spectrum are analyzed. The calculated results show that each of all the clusters of WnNim (n+m=8) has a polarity, and W-rich clusters which have a strong nonlinear optical effect each and are easy to be polarized by external electromagnetic field, that vibrational frequencies are mainly distributed in a 0–350 cm-1 range, but the cluster of W4Ni4, due to the particularity of vibration mode, has a obviously strong peak on IR spectrum and also on Raman spectrum, each at a frequency of 421.971 cm-1, and that the W5Ni3 cluster, with high symmetry of C3v point group, presents a resonance phenomenon on IR spectrum.
Acoustic scattering from a finite quasi-periodic bulkhead cylindrical shell
Authors: Pan An  , Fan Jun  , Zhuo Lin-Kai  ,   State Key Laboratory of Ocean Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
Published: December 2020

Research on sound scattering from a finite quasi-periodic bulkhead cylindrical shell is conducted. The small deviation of bulkhead array exists. Firsts some applications are given to investigate the problem of backscattering from a periodic bulkhead cylindrical shell in order to verify the theory. Then the angle-frequency spectrum of the backscattering from quasi-periodic bulkhead cylindrical shell is calculated, and the angle-frequency spectrum shows that the quasi-periodic array of bulkhead results in the diffusion of Bloch-Floquet wave and background field. However, the resonance of bulkheads is covered by background field. Finally, the influences of the array random variable of bulkheads, the number of bulkheads and the spacing between bulkheads are discussed. The calculations show that the diffusion of Bragg waves is more evident with array random variable increasing; the power of Bragg waves is concentrated with the number of bulkheads increasing; with the spacing between bulkheads becoming broad, the number of Bragg waves increases and the diffusion of high modes Bragg waves becomes more serious. Based on the geometric characteristics of Bragg waves, the approximate calculation formula of the Bragg wave position on the angle-frequency spectrum is presented. The formula can forecast the position of Bragg wave on the angle-frequency spectrum exactly and the diffusion of Bragg waves roughly when the bulkheads array quasi-periodic.
The response property of one kind of factional-order linear system excited by different periodical signals
Authors: Yang Jian-Hua  , Zhu Hua  ,   School of Mechanical and Electrical Engineering, China University of Mining and Technology, Xuzhou 221116, China
Published: December 2020

Under excitations of different periodical signals, the response of a fractional linear system is investigated. First, by the harmonic balance method, the approximate solutions of the fractional-order linear system excited by harmonica signals are obtained. The results in this paper are idenified with the existing results obtained by the average method (Shen Y J, Yang S P, Xing H 2012 Acta Phys. Sin. 61 110505). However, the solving process here is much simpler. Further, the value of the fractional-order is extended in this paper. Then, according to the Fourier expansion and the method of linear superposition, the response of the system to a general periodical signal is obtained, and two examples are given for the case of periodical square wave and modulus of sine wave respectively. The results in this paper show that the value of the factional-order influences the resonance frequency and resonance amplitude of each order harmonic. The monotonicity between the response amplitude and the value of the fractional-order is influenced mainly by the frequency of the external excitation. Besides the analytical analysis, the numerical simulations are also performed, and the approximate solutions are in good agreement with the numerical ones. Hence, the process of the analysis of this paper is feasible.
The mechanism of effect of lens-to-sample distance on laser-induced plasma
Authors: Liu Yue-Hua  , Chen Ming  , Liu Xiang-Dong  , Cui Qing-Qiang  , Zhao Ming-Wen  ,   School of Physics and State Key Laboratory of Crystal Materials, Shandong University, Jinan, Shandong 250100, China
Published: December 2020

The analysis of nanosecond laser-induced plasma versus the lens-to sample distance(LTSD) is investigated by 532nm laser ablated Ti-Al alloys in air and vacuum condition. The results indicate that electron temperature and density increase rapidly with the LTSD changing from short distance to the focal length (f=111 mm). Moreover, the plasma parameters by laser ablation in vacuum condition will further increase with LTSD further increasing. As for ambient medium, the plasma parameters reach their maximum values at 107 mm and then substantially decrease. On the other hand, the electron temperature and density rise again, while the intensity of Ti(II)368.52 nm decreases rapidly when the LTSD extends 112 mm.
Characterization of TiB2 synthesized at high pressure and high temperature
Authors: Li Jun-Jun  , Zhao Xue-Ping  , Tao Qiang  , Huang Xiao-Qing  , Zhu Pin-Wen  , Cui Tian  , Wang Xin  ,   State key lab of superhard materials, Jilin University, Changchun 130012, China
Published: December 2020

Bulk titanium borides (TiB2) have been successfully synthesized from the stoichiometric boron and titanium powders at high pressure and high temperature (HPHT). The density of TiB2 is higher than 99%. The Vicker's hardness of TiB2 as synthesized is 39.6 GPa which is near to result of the supehard materials. While TiB2 show good metallic characters with the resistivity, 10-8 Ωm, which is near to the value of the single crystal of TiB2. The enhanced properties of TiB2 as synthesized may be attributed to the higher density and uniform crystal size.
Determination of photoelectric current by voltage between anode and cathode, intensity and frequency of light
Authors: Liu Chang-Shi  , Liu Wen-Li  ,   Nan Hu College, Jiaxing University, Zhejiang 314001, China;,   College of mathematics, physics and information engineering, Jiaxing University, Zhejiang 314001, China
Published: December 2020

Based on the Fermi-Dirac distribution, a typical numerical method to calculate photoelectric current by voltage between anode and cathode in vacuum is developed. The results of simulations agree very well with the observed curves consisting of photoelectric current and voltage. Then, the contribution of intensity of incident light to photoelectric current is obtained mathematically. Finally, the wavelength of incident light is related to photoelectric current theoretically. Hence, photoelectric current can be predicted.