bluuebunny/crossref_metadata_2025 huggingface dataset:
Research on convective cooling effect of leading edge platelet of airfoil
Authors: Sun Jian  , Liu Wei-Qiang  ,   Science and Technology on Scramjet Laboratory, National University of Defense Technology, Changsha 410073, China
Published: December 2020

A convective cooling platelet structure is a considered as thermal protection system to prevent the leading edge of airfoil from the serious aerodynamic heating. The cooling effect parameter is proposed in this paper. By the use of fluid structure interaction method, the cooling effect of convective cooling structure is investigated under given condition. The minimum that is 0.25 when the coolant is water occurs on the leading edge of airfoil head. The research shows that the increases with the increase of channel aspect radio () and reaches a stable value that indicates that the cooling effect is saturated. Situation unfavorable for cooling may occur if the keeps increasing. And the decreases with the radio of airfoil's head decreasing. With coolant flux increasing, the also increases to a stable value and the pressure drop between inlet and outlet increases rapidly when the structure and the material of the convective cooling platelet structure are fixed. Considering the pressure brought to the supply system due to the increase of flux, we should choose the optimal coolant flux value in order to obtain better cooling effect. Both the inner coolant groove and the external refractory protection should be of high thermal conductivity material which can strengthen the heat transfer of structure and enhance the cooling effect.
Time periodic electroosmotic flow of the generalized Maxwell fluids between two micro-parallel plates with high Zeta potential
Authors: Chang Long  , Jian Yong-Jun  ,   School of Mechanical Science, Inner Mongolia University, Hohhot, Inner Mongolia 010021, China;,   School of Mathematics and Statistics, Inner Mongolia Finance and Economics College, Hohhot, Inner Mongolia 010051, China
Published: December 2020

In this study, semi-analytical solutions are presented for the time periodic (electroosmotic flow) of linear viscoelastic fluids between micro-parallel plates. The linear viscoelastic fluids used here are described by the general Maxwell model. The solution involves analytically solving the nonlinear Poisson-Boltzmann (P-B) equation, the Cauchy momentum equation and the general Maxwell constitutive equation. By numerical computations, the influences of the dimensionless wall Zeta potential0, the periodic EOF electric oscillating Reynolds number Re, and normalized relaxation times 1 on velocity profiles are presented. Results show that for prescribed electrokinetic width K, relaxation time 1 and oscillating Reynolds number Re, higher Zeta potential 0 will lead to larger amplitude of EOF velocity, and the variation of velocity is restricted to a very narrow region close to the Electric double-layer. In addition, with the increase of relaxation time 1, the elasticity of the fluid becomes conspicuous and the velocity variations can be expanded to the whole flow field. For prescribed Re, longer relaxation time 1 will lead to quick change of the EOF velocity profile, and the amplitude becomes larger gradually.
Growth and photoluminescence character research of aluminum nitride nanowires upon carbon foam substrate
Authors: Cheng Sai  , Lü Hui-Min  , Shi Zhen-Hai  , Cui Jing-Ya  ,   Department of Applied physics, Xi'an University of Technology, Xi'an 710048, China;,   Department of Applied chemistry, Xi’an University of Technology, Xi’an 710048, China
Published: December 2020

To simplify preparation process of AlN/C composite foam, AlN nanomaterials are prepared via double decomposition reaction and then 800℃ annealing process to recrystallize hexagonal AlN (h-AlN) nanowires on carbon foam substrate. Fore the morphology characterization it follows that, h-AlN nanowires with straight cylindrical morphology grow along the [001]direction on carbon microspheres surface and are about 50 nm in diameter and several micrometers in length. Meanwhile, the growth mechanism of nanowire is interpreted as vapor-liquid-solid(VLS) process. The photoluminescence(PL) spectrum of as-prepared sample also researched, and the results show that a sharp photoluminescence peak appears at 423 nm and shifts toward the red side with temperature increasing. The peak is attributed to the transition luminescence, owing to the substitution of C for N impurity energy level. The sample has good PL character in purple light band and is potential to be used the in photodetector field.
Electronic structures and optical properties of AAl2C4 (A=Zn, Cd, Hg; C=S, Se) semiconductors
Authors: Chen Dong  , Xiao He-Yang  , Jia Wei  , Chen Hong  , Zhou He-Gen  , Li Yi  , Ding Kai-Ning  , Zhang Yong-Fan  ,   Fujian Provincial Key Laboratory of Photocatalysis-State Key Laboratory Breeding Base, College of Chemistry and Chemical Engineering, Fuzhou University, Fuzhou 350108, China
Published: December 2020

First-principles density functional calculations are performed to study the geometries, the electronic and the optical properties of AⅡAl2C4Ⅵ (A =Zn, Cd, Hg; C = S, Se) semiconductors each with a defect chalcopyrite structure. For the linear optical properties, five compounds show good transmissions of light in the IR and part of visible regions, and among them HgAl2S4 and HgAl2Se4 possess moderate birefringences. For the nonlinear optical properties, the strong second harmonic generation (SHG) response can be expected for these crystals, and the large static SHG coefficients ( 20 pm/V) are predicted in this work. The SHG response of AⅡAl2C4Ⅵ semiconductors can be attributed to the transitions from the bands near the top of valence band which are derived from S/Se p states to the unoccupied bands that are contributed by p states of Al and Hg atoms. By comparing with the optical properties of the commercialized AgGaC2 crystals, our results indicate that HgAl2S4 and HgAl2Se4 compounds are good candidates for the second-order nonlinear optical crystals in the IR region.
Super broadband near infrared luminescence properties in Bi-doped aluminosilicate glasses
Authors: Zhou Da-Cheng  , Liu Zhi-Liang  , Song Zhi-Guo  , Yang Zheng-Wen  , He Xi-Jia  , Wang Rong-Fei  , Jiao Qing  , Qiu Jian-Bei  ,   School of Material Science and Engineering, Kunming University of Science and Technology, Kunming 650093, China
Published: December 2020

Influences of alkaline earth oxides on super broadband near infrared luminescence properties from Bi-doped RO-Al2O3-SiO2 (R=Ca, Sr, Ba) aluminosilicate glasses are investigated. The results show that under different pumping sources, the near infrared (NIR) luminescence shows different behaviors. Under 808 nm excitation, the infrared emission located at 1300 nm with lifetime more than 600 ms is observed, whose intensity increases with the increase of ionic radius. However, under 690 nm excitation, the luminescence at 1100 nm with a full width at half maximum of 400 nm decreases with the increase of ionic radius. According to the above results, it is suggested that infrared emissions may originate from Bi+ and BiO.
The luminescence properties of a novel electron trapped material Sr2SnO4:Sb3+ for optical storage
Authors: Wang Zhi-Long  , Zheng Gui-Seng  , Wang Shi-Qin  , Qin Qing-Song  , Zhou Hong-Liang  , Zhang Jia-Chi  ,   Gansu University of Traditional Chinese Medicine, Lanzhou 730000, China;,   School of Physical Science and Technology, Lanzhou University, Lanzhou 730000, China
Published: December 2020

A novel electron trapped material Sr2SnO4:Sb3+ for optical storage is successfully obtained by conventional solid state method at 1300℃ It indicates that the 1S0 1P1 (208 nm) and 1S0 3P1 (265 nm) transitions of Sb3+ are the most efficient writing light source. Its emission covers 400700 nm and can be attributed to 3P0,1 1S0 transition of Sb3+. We can observe yellowish white light and its color coordination is (0.341, 0.395). The thermoluminescence of Sr2SnO4:Sb3+ contains four peaks at about 39 ℃, 124 ℃, 193 ℃ and 310 ℃, respectively. The intensity of peak at 39 ℃ is low and thus it has a weak afterglow which can last only 140 s. However, even after putting it in dark for 1 day, the peak at 310 ℃ can still keep 45.6% of its original intensity and can be efficiently stimulated by 980 nm infrared laser. As a conclusion, the Sr2SnO4:Sb3+ is a promising electron trapping material for application in optical storage.
Mechanism study of a THz source using field emission array
Authors: Liu Wei-Hao  , Zhang Ya-Xin  , Hu Min  , Zhou Jun  , Liu Sheng-Gang  ,   Terahertz Science and Technology Research Center, University of Electronic Science and Technology of China, Chengdu 610054, China
Published: December 2020

The micro-vacuum electronic device is one of the most promising sources for the generation of high power THz-wave radiations. In this paper, the systematical theoretical analyses and computer simulations on the physical mechanism of a kind of micro-vacuum electronic THz radiation source based on the cathode of field-emission array (FEA) are carried out. The mode matching method is used to study the electromagnetic characteristics of the structure, and -mode is confirmed to be an optimal operation mode for its field distribution. Linear theory (small signal theory) is used to analyze the beam-wave interaction of this kind of source, and the starting condition of the -mode oscillation is derived. The premodulation of electron beam emitted from FEA and the electron transit time effect in the interaction gap are the physical cause of the electromagnetic oscillation. These results are well verified by the computer simulations.
Relationship between the South China Sea summer monsoon and the first-landfall tropical cyclone over mainland of China
Authors: Zhang Han  , Guan Yu-Ping  ,   State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China;,   Graduate University of Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

This study investigates the relationship between the South China Sea summer monsoon and the first tropical cyclone (TC) of the season to make landfall over mainland China (in short, the first-landfall TC) using the South China Sea summer monsoon index, NCEP/NCAR reanalysis monthly average data, and best-track TC data from Joint Typhoon Warning Center (JTWC) for 19482009. The results show that the characteristics of the first-landfall TC are closely associated with the frequency, active stage, and strength of subsequent landfall TCs in the same year. In detail, a stronger (weaker) South China Sea summer monsoon index year corresponds to more (fewer) landfall TCs over Mainland China, a later (earlier) date of the first-landfall TC, a lower (higher)-latitude landing point of the first-landfall TC, and a stronger (weaker) monsoon trough. The anomalous wind field and the track of the first-landfall TC are also significantly related to the strength of the index. The location of the first-landfall TC has shows a gradual trend toward higher latitudes over the analysis period, and there is a decreasing trend in the variability of the South China Sea summer monsoon index.
The stability of solitay wave solution to a modified Kadomtsev-Petviashvili equation
Authors: Zhang Juan  , Zhou Zhi-Gang  , Shi Yu-Ren  , Yang Hong-Juan  , Duan Wen-Shan  ,   College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070, China
Published: December 2020

The reductive perturbation method is employed to describe the behaviour of ion-acoustic waves for plasmas in the absence of magnetic field, leading to a type of modified Kadomtsev-Petviashvili equation. The stability of a special type of solitary wave solutions for the modified Kadomtsev-Petviashvili equation is investigated with a finite difference scheme. The numerical results show that this solitary wave is unstable under two particular initial perturbations.
Maximum correlation at the transition to the saturation regime of nonsequential double ionization
Authors: Xin Guo-Guo  , Zhao Qing  , Liu Jie  ,   School of Science, Beijing Institute of Technology, Beijing 100081, China;,   Science and Technology Computation Physics Laboratory, Institute of Applied Physics and Computational Mathematics, Beijing 100088, China
Published: December 2020

The nonseqential double ionization of helium in the laser with intensities ranging from blow the recolliding ionization threshold to near the sequential double ionization regime is studied systematically. We obtain the probability ratio between correlation and anti-correlation of the two final electrons, and find the maximum ratio is in the transition region to the saturation regime of nonsequential double ionization. The maximum ratio generation course is shown in correlated two-electron longitudinal momentum spectrum, and the deep mechanism is investigated by orbit back-trace analysis. The rescattering of one electron after recollision and the high speed recollision of the tunneled electron lead to the increases of anticorrelation ratio in low- and high- intensity laser fields respectively.
Ray ellipse method of analyzing the power and polarization state of partially polarized light
Authors: Liu Chao  , Cen Zhao-Feng  , Li Xiao-Tong  , Xu Wei-Cai  , Shang Hong-Bo  , Neng Fen  , Chen Li  ,   State Key Laboratory of Modern Optical Instrumentation, Zhejiang University, Hangzhou 310027, China;,   State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Phisics, Chinese Academy of Sciences, Changchun 130033, China
Published: December 2020

It is difficult to cope with the changes in power and polarization for partially polarized light. The light polarization will also affect the image quality, especially for imaging with large numerical aperture. A novel method of analyzing the power and the polarization state of partially polarized light is proposed in this paper. This method has a good intuitiveness and requires much smaller computation. An aplanatic lens system is simulated. Polarization effect caused is analyzed with this method. The results show that for the imaging light the intensity of TM polarized light relatively increases because of large numerical aperture, which will influence image contrast. Imaging in high refractive index medium can be used to improve this problem.
The electric and magnetic polarization singularities of Gaussian vortex beam in the free-space propagation
Authors: Luo Ya-Mei  , Lü Bai-Da  , Tang Bi-Hua  , Zhu Yuan  ,   Department of Biomedical Engineering, Luzhou Medical College, Luzhou 646000, China;,   Institute of Laser Physics & Chemistry, Sichuan University, Chengdu 610064, China
Published: December 2020

Using the Fresnel vector diffraction integral and taking the Gaussian vortex beam as an example, the analytical expressions for the electric and magnetic components of Gaussian vortex beam propagating in the free-space are derived, and used to study the variations of electric and magnetic polarization singularities in free space. It is found that there exist two-dimensional (2D) and three-dimensional (3D) electric and magnetic polarization singularities in the free-space, which do not coincide in general. By varying waist width ratio, amplitude ratio, and propagation distance, the motion of polarization singularities takes place. In the 2D and the 3D electric and magnetic fields, the V-point may appear under a certain condition.
Focal depth research of digital holographic reconstructed image
Authors: Li Jun-Chang  ,   Faculty of Science, Kunming University of Science and Technology, Kunming 650093, China
Published: December 2020

Regarding the object scattering light as a superposition of light waves emitting from a lots of point sources on object surface of which phases have random values, in the paper, wee investigate the diffracted field of digital holographic reconstructed image and defocused image. The definition of depth of focal (DOF) is also given based on the feature that the reconstructed image is displayed in pixels. According to the characteristic that the physical dimensions of pixel are associated with computation method, focal depth expressions are deduced when image is reconstructed with different algorithms. Finally, experimental verification is given.
Ultrahigh-Q small-V photonic crystal nanobeam cavities based on parabolic-shaped width and taper holes
Authors: Feng Chen  , Feng Guo-Ying  , Chen Nian-Jiang  , Zhou Shou-Huan  ,   College of Electronics & Information Enigineering, Sichuan Universtiy, Chengdu 610064, China;,   North China Research Institute of Electro-Optics, Beijing 100015, China
Published: December 2020

One-dimensional (1-D) photonic crystal (PhC) nanobeam cavity based on parabolic-shaped width and tapered holes was proposed and analyzed. Finite-difference time-domain simulations show that both an ultrasmall modal volume (V～ 0.04(λ /n)3) and ultrahigh quality factor (Q～ 1.8× 107) can be obtained in PT PhC nanobeam cavity. In addition, the PT PhC nanobeam have one order lower V comparing to parabolic and tapered nanobeam. With compactness, lower fabrication requirements to achieve ultrahigh Q/V, the proposed nanobeam could be versatile platforms of interest for optical communications, optomechanics, cavity QED, etc.
Research on a cylindrical cloak with active acoustic metamaterial layers
Authors: Shen Hui-Jie  , Wen Ji-Hong  , Yu Dian-Long  , Cai Li  , Wen Xi-Sen  ,   Key Laboratory of Science and Technology on Integrated Logistics Support, National University of Defense Technology, Changsha 410073, China
Published: December 2020

Enlightened by the tunable properties of effective density of the active acoustic metamaterial, we design an active infinite cylinder acoustic cloak according to the idea of the multilayer structured acoustic cloak with homogeneous isotropic materials. Utilizing the electrical analog, the dynamical equation of the acoustic cavity with Piezo-Diaphragm is presented. By analyzing the circuit diagram, the control strategy of achieving various effective densities which are used for constructing the acoustic cloak is given. Based on the necessary parameters such as the wide range values of the relative densities gained by active control, and the acoustic speed of each composite layer, the acoustic pressure field of the plane wave incident on the cloak is calculated, via the FEM model. Also the pressure map of a rigid cylinder scatterer with surrounded fluid is performed for comparison. Results show that outside the cloaking shell, the plane wave field is almost undisturbed. However inside the shell, the plane wavefronts are gradually deflected, and guided around the cloaked domain, returning to the original plane shape with small perturbation. This phenomenon making the cloak acoustically invisible in some frequency ranges has useful values in engineering applications. Finally, the total scattering cross section of the cloak is calculated to investigate the invisible effect according to the frequency domain. The total number of the composite active metamaterial layers is 15, which is much easier to realize in experiment.
Experimental study and improvement of frequency lowering algorithm in Chinese digital hearing aids
Authors: Liang Rui-Yu  , Xi Ji  , Zhao Li  , Zou Cai-Rong  , Huang Cheng-Wei  ,   College of Computer and Information, Hohai University, Nanjing 210098, China;,   School of Information Science and Engineering, Southeast University, Nanjing 210096, China
Published: December 2020

Frequency lowering algorithms are the most effective and secure for improving the auditory identification capability of hearing-impaired patients. Through analyzing the current algorithms by the test of subjective auditory approach, in the paper we propose an adaptive algorithm combining slow playback algorithm with frequency transition algorithm. The algorithm can adaptively adjust playback ratio according to the signal spectrum structure to reduce the desynchronization in time region. Furthermore, a method of evaluating the playback ratio in noise is designed based on the frequency spectrum relation between noise and noisy signal. Results showed that compared with other frequency lowering algorithms, the proposed algorithm can improve the auditory identification capability from 15% to 20%. In addition, in the test for hearing-impaired person, the significant improvement on the average auditory identification capability is also obtained compared with the conventional hearing aid device.
Study on ultra fast nonequilibrium heat transfers in nano metal films by femtosecond laser pump and probe method
Authors: Zhu Li-Dan  , Sun Fang-Yuan  , Zhu Jie  , Tang Da-Wei  ,   Institute of Engineering Thermophysics, Chinese Academy of Sciences, Beijing 100190, China;,   Graduate University of the Chinese Academy of Sciences, Beijing 100039, China
Published: December 2020

The reduction in size and the increase in speed of microelectronic device make the probability of nonequilibrium electron-phonon phenomena become greater, leading to the increase of thermal resistance in the device. The measurement of electron-phonon coupling factor in material resistance increasingly becomes important for accurate thermal treatment. The femtosecond laser pump and probe method is used for studing the nonequilibrium heat transfer in nano metal films with different thicknesses. Exploring parabolic two-step model (PTS) to fit the experimental data. During the fitting process, we considered the proportional relationship between the changes of electron temperature and phonon temperature, which affects the reflectivity. By studying the different thicknesses of Ni and Al films electron-phonon coupling factors, we find that the electron-phonon coupling factor does not change with film thickness. In addition, the experimental result verifies that the reflectivity of probe laser is affected by electron temperature and phonon temperature at the same time. Through the data analysis, we also get the influence coefficients of electron temperature and phonon temperature on reflectivity.
Shock timing experiment based on imaging velocity interferometer system for any reflector
Authors: Wang Feng  , Peng Xiao-Shi  , Mei Lu-Sheng  , Liu Shen-Ye  , Jiang Xiao-Hua  , Ding Yong-Kun  ,   Research Center of Laser Fusion, China Academic of Engineering and Physics, Mianyang 621900, China
Published: December 2020

The timing of multiple shock waves is crucial technique to the performance of inertial confinement fusion ignition targets. With the requirement for shock timing, the timing ability of Shen Guang-III prototype is analyzed by experimental data of two shots. The laser pulse in Shen Guang-III prototype is shaped in time scale, and the window material is z-cut quartz. The stream lines of two shock waves in quartz target are presented with Multi-1D program. Two steps of radiation drive two shock waves that coalesce in the quartz target, the resulting history, coalesce times, and transit times are observed in the stream lines. With the experiment results of two shots, the consistence of resulting history and coalesce times of two shock waves is provided under the same condition of laser pulse, target and diagnostic parameter. The differences in shock wave velocity, fringe contrast and quality occur at coalesce times of two shock waves. And the reflectivity of second shock wave does not increase compared with that of first shock wave. These experimental results and method provide the strong support for shock timing technique.
A small-angle X-ray scattering study of micro-defects in thermally treated HMX
Authors: Yan Guan-Yun  , Tian Qiang  , Huang Chao-Qiang  , Gu Xiao-Min  , Sun Guang-Ai  , Chen Bo  , Huang Ming  , Nie Fu-De  , Liu Yi  , Li Xiu-Hong  ,   Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900, China;,   Institute of Chemical Materials, China Academy of Engineering Physics, Mianyang 621900, China;,   Institute of Shanghai Apply Physics, Chinese Academy of Sciences, Shanghai 201800, China
Published: December 2020

The defects in HMX, induced by thermal expansion, phase transition and chemical decomposition, have large effects on the performance of HMX. In this work, the defects of HMX samples under heat treatment are characterized by small angle X-ray scattering (SAXS) and atomic force microscopy. A large number of pores with an average size of 10 nm are found during the - phase transition of HMX (180℃), and the pores increase in size and decrease in number with time increasing. A new population of small pores with sizes of 58 nm are produced in HMX during the thermal decompositions (190℃ and 200℃). The size and the number of the small pores increase with temperature increasing.
Vibrational dynamics of water confined in mesoporous silica under low temperature
Authors: Huang Xiu-Feng  , Pan Li-Qing  , Li Chen-Xi  , Wang Qiang  , Sun Gang  , Lu Kun-Quan  ,   Department of Physics, College of Mathematics and Science, University of Science and Technology Beijing, Beijing 100083, China;,   Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
Published: December 2020

The Raman vibrational spectra of water inside mesoporous silicate are measured in a temperature range of 100 T 303 K. It is found that the Raman spectrum of confined water becomes more different from that of bulk water with the decrease of water content in pores. For samples with high water content in pore, the main peak position of the Raman spectrum of water changes abruptly in a narrow temperature range. However, when water content decreases down to 20%, the red shift of the main peak of the Raman spectrum is continuous with temperature decreasing. At the same time, its temperature-dependence is the same as that of bulk amorphous ice.
The model of valence-band dispersion for strained Ge/Si1-xGex
Authors: Dai Xian-Ying  , Yang Cheng  , Song Jian-Jun  , Zhang He-Ming  , Hao Yue  , Zheng Ruo-Chuan  ,   School of Microelectronic,Key Laboratory of Ministry of Education for Wide Band-Gap Semiconductor Materials and Devices, Xidian University, Xi'an 710071, China
Published: December 2020

Based on the kp theory, the valence-band dispersion model for biaxial strained Ge/Si1-xGex is derived by taking strained Hamiltonian perturbation into account. The model can be used to calculate the valence band structure and hole effective mass along arbitrarily k wavevector direction in strained Ge grown on arbitrarily oriented relaxed Si1-xGex virtual substrate. The MATLAB simulation results of the model show that by comparison with relaxed Ge, the more anisotropy of the hole effective mass occurs in strained Si1-xGex and the hole effective mass of the top valence band decreases with the increase of Ge fraction. The results can supply valuable references to the conduction channel design related to stress and orientation in the Si-based strained Ge MOS devices and integrated circuits.
Progress in terahertz surface plasmonics
Authors: Wang Yue  , Wang Xuan  , He Xun-Jun  , Mei Jin-Shuo  , Chen Ming-Hua  , Yin Jing-Hua  , Lei Qing-Quan  ,   Department of Electronicl Science and Technology, Harbin University of Science and Technology, Harbin 150080, China;,   Key Laboratory of Engineering Dielectrics and Its Application, Ministry of Education, Harbin University of Science and Technology, Harbin 150080, China;,   College of Electric and Electronic Engineering, Harbin University of Science and Technology, Harbin 150080, China
Published: December 2020

Plasmonics, which deals with the unique optical properties of metallic and semiconductor nanostructure, is one of the most fascinating and fast-moving areas of photonics. Its board scale research in the visible, infrared, terahertz and microwave frequencies has driven by the advances in the micro/nano fabrication and the computational simulation technologies, as well as the potential applications in areas of high sensitivity bio-chemical sensing, sub-wavelength light-guiding, near-field microcopy, and nanolithography. Especially, the development of the artificial metamaterial has laid the good foundation for the material and devices in the terahertz frequency range, which is barely responded by the nature materials, and furthermore, has promoted the progress of terahertz surface plasmonics. In this paper the generation, propagation, new applications, and perspective of terahetz surface plamonics are reviewed and discussed.
Effects of Fe doping on the crystal structures and photoluminescences of ZnO: Ni thin films prepared by sol-gel method
Authors: Wu Zhong-Hao  , Xu Ming  , Duan Wen-Qian  ,   Key Laboratory of Information Materials of Sichuan Province, School of Electrical and Information Engineering, Southwest University for Nationalities, Chengdu 610041, China
Published: December 2020

Zn0.95-xNi0.05FexO (x=0, 0.005, 0.01, 0.03, 0.05) thin films are fabricated on the glass substrates by the sol-gel method. The surface morphologies and crystal structures of the films are investigated using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results reveal that preferential orientations are all along the (002) direction in all films. the qualities of ZnO: Ni films for low or high Fe concentration become worse, the crystal grain sizes of ZnO: Ni film are reduced, but moderate Fe doping seems to improve the film quality. XPS results reveal that Ni elements exist as Ni2+, and Fe elements exist as Fe2+ and Fe3+. Strong ultraviolet emission peaks, blue double emission peaks and green emission peaks are observed in the photoluminescence spectra of all samples at room temperature. It is found that the PL intensities of (Ni, Fe) co-doped ZnO films could be well modulated by Fe doping. In combination with other reports, we think that the ultraviolet emission peaks are due to exciton recombination; while the blue double peaks are caused by transition of electrons from the zinc interstitial to the top of the valence band or from the oxygen vacancy to the zinc vacancy. However, the green peak is highly dependent on oxygen vacancy and zinc vacancy formed by doping.
Fabrication and magnetic properties of Co70Cu30 alloy nanowire arrays with high coercivity
Authors: Liu Xiao-Xu  , Zhao Xing-Tao  , Zhang Ying  , Zhu Yan  , Wu Guang-Heng  ,   College of Physics and Chemistry, Hebei Normal University of Science & Technology, Qinhuangdao 066004, China;,   State Key Laboratory of Metastable Materials Science and Technology, Electrical Engineering College of Yanshan University, Qinhuangdao 066004, China;,   Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
Published: December 2020

CoCu solid solution alloy nanowire arrays which exhibit the face-centered cubic structure with strong [220] orientation along the nanowire axes are fabricated for first time in the anodic aluminum oxide template by electrodeposition. The proportion of Co ingredient in CoCu alloy nanowire arrays is up to 70%. Transmission electron microscopy revealts that the nanowire arrays are uniform and continuous and have a large aspect ratio of about 300. The magnetic hysteresis loop demonstrates that the Co70Cu30 alloy nanowire arrays have a large coercivity of about 2438 Oe and relatively large squareness of about 0.76 parallel to nanowire arrays which greatly exceeds the value previousely reported. Good magnetic properties are achieved due mainly to the larger proportion of Co ingredient than that in the normal CoCu alloy nanowire arrays and the large shape anisotropy. The results of magnetic measurement and the calculations from formula demonstrate that the symmetric fanning mechanism of sphere chains model could be employed to explain the magnetization reversal process which is related to the structure of the Co70Cu30 nanowire arrays.
Nonlinear evolution equation with variable coefficient G'/G expansion solution
Authors: Pang Jing  , Jin Ling-Hua  , Zhao Qiang  ,   College of Sciences, Inner Mongolia University of Technology, Hohhot 010051, China
Published: December 2020

In this paper, the (G'/G)-expansion method is used to solve the two kinds of nonlinear KdV equations with variable coefficients for the first time. And some new exact solutions are obtained successfully. It is proved that the (G'/G)-expansion method is not only appropriate for solving nonlinear evolution equations with constant coefficients but also excellently applicable to the nonlinear evolution equations with variable coefficients, and it also has a broad application prospect.
Interaction of multi-optical solitions in the three-level gaseous media
Authors: Sun Jian-Qiang  , Luo Si-Yu  , Cai Bai-Guang  ,   College of Information and Science Technology, Hainan University, Haikou 570228, China
Published: December 2020

Optical solitons in gaseous atomic media display many striking features under electromagnetically induced transparency (EIT). Study of theoretical model, which describes these features of optical solitons, has important meaning in optical informational process and propagation. Two-dimensional saturated nonlinear Schrdinger equation, which describes the spatial soliton evolution in the three-level gaseous atomic EIT media, is transformed into the Hamilton system with the symplectic structure. The Hamilton system is discretizated by the symplectic method. The corresponding symplectic scheme is obtained. Evolution behaviors of two and four spatial solitons with the same amplitude in a three-level, gaseous atomic EIT media are simulated by the symplectic scheme. Numerical results further show that the phase difference and the direction of the entering gauss beams have an obvious effect on the interaction of multi-solitons. The entering Gauss beam can form the stable optical solitons in a gaseous atomic media.
Adaptive modified function projective synchronization of a class of chaotic systems with uncertainties
Authors: Deng Wei  , Fang Jie  , Wu Zhen-Jun  , Wu Yan-Min  ,   Henan Key Laboratory of Information-Based Electrical Appliances, School of Electrical Information Engineering, Zhengzhou University of Light Industry, Zhengzhou 450002, China
Published: December 2020

In this paper, we primarily investigate the adaptive modifying function projective synchronization of a class of chaotic systems with uncertainties. According to the Lyapunov stability theory, the two schemes of obtaining the response system from chaotic system are established, and the controller and the adaptive law are designed. The approach is more robust to noise and external interference, and does not need the upper bound of uncertainties in advance. In addition, it can adjust the system response rapidly by adjusting the accelerated factor. This method is more practical. Numerical simulations of a hyper-chaotic system verify the effectiveness of the proposed method.
Multiple solitoff solutions and the evolution of (2+1)-dimensional breaking soliton equation
Authors: Cao Xiao-Xia  , Ma Song-Hua  , Ren Qing-Bao  , Yang Zheng  ,   College of Technology, Li shui University, Lishui 323000, China;,   College of Science, Lishui University, Lishui 323000, China
Published: December 2020

With the help of the symbolic computation system Maple, an extended G'/G method and a variable separation method, new exact solutions of the (2+1)-dimensional breaking soliton equation are derived. With the derived solitary wave solutions, we obtain multi Solitoff localized structures and study the soliton evolution with time.
Effect of Mn4+ doping on the microstructure and electrical property of BiFeO3 ceramic
Authors: Zhang Qiang  , Zhu Xiao-Hong  , Xu Yun-Hui  , Xiao Yun-Jun  , Gao Hao-Bin  , Liang Da-Yun  , Zhu Ji-Liang  , Zhu Jian-Guo  , Xiao Ding-Quan  ,   Department of Materials Science, Sichuan University, Chengdu 610064, China
Published: December 2020

Multiferroic BiFe1-xMnxO3 (x= 0, 0.05, 0.10, 0.15, 0.20) (represented as BF1-xMxO) ceramics are prepared by the conventional solid state reaction technique. The effects of Mn4+ doping on density, phase structure, morphology, dielectric and ferroelectric properties are investigated. The X-ray diffraction patterns of the samples indicate that the typical perovskite phase structure of BiFeO3 is formed, and a phase transition starts near x= 0.05, i.e., the phase structure is distorted from rhombohedral to orthorhombic by Mn4+ doping. The dielectric susceptibility of the sample is significantly increased and the dielectric loss is slightly increased with the increase of Mn4+ content. The dielectric constant r of the BiFe0.85Mn0.15O3 ceramic at 10 kHz is as high as 1065, 22 times larger than that for pure BiFeO3. It is suggested by hysteresis loop measurements that the ferroelectric property of the BF1-xMxO ceramics is improved and the remanent polarization is increased by Mn4+ doping. This is probably because Mn4+ is more stable than Fe3+, and the B-site doping with higher valent Mn4+ could reduce the volatilization of Bi3+ and suppress the valence fluctuation of Fe3+, thereby reducing the concentration of oxygen vacancies and the leakage current in the ceramic.
Investigation of electromagnetic scattering interaction between the column with rectangular cross-section and rough land surface covered with snow using finite difference time domain method
Authors: Ren Xin-Cheng  , Guo Li-Xin  , Jiao Yong-Chang  ,   National Laboratory of Antennas and Microwave Technology, Xidian University, Xi'an 710071, China;,   School of Physics and Electronic Information, Yanan University, Yan'an 716000, China;,   School of Science, Xidian University, Xi'an 710071, China
Published: December 2020

The dielectric properties of the actual land surface and snow deposit are described using the four-component model of dielectric constant of soil and the dielectric constant model of snow respectively. The actual rough land surface is simulated with the model of exponential type distribution rough surface and Monte Carlo method, the composite electromagnetic scatterings from the rough land surface covered with snow and the column with rectangular cross-section above it are studied using the finite-difference time-domain method, the curves of angular distribution of composite scattering coefficient are obtained, the bistatic composite scattering coefficient varying with the roughness parameter and dielectric parameter of soil and snow, the geometric parameter and dielectric parameter of the column with rectangular cross-section are calculated in detail. The characteristics of the composite scattering coefficient from rough land surface covered with snow and the column with rectangular cross-section above it are also obtained.
Research on spatial coherence of undulator source in Shanghai synchrotron radiation facility
Authors: Wang Hua  , Yan Shuai  , Yan Fen  , Jiang Sheng  , Mao Cheng-Wen  , Liang Dong-Xu  , Yang Ke  , Li Ai-Guo  , Yu Xiao-Han  ,   Shanghai Institute of Applied Physics, Shanghai Synchrotron Radiation Facility, Chinese Academy of Sciences, Shanghai 201204, China
Published: December 2020

Firstly, based on the Gaussian-schell model source theory and the propagation of cross-spectral density function in free space, the spatial coherence of undulator source (BL15U) in Shanghai Synchrotron Radiation Facility is studied. Secondly, the influences of pre-focusing mirror and the monochromator on the beam spatial coherence are discussed. Finally, the spatial coherent length at mono slit S2 is measured. The spatial coherent length at S2 theoretically is 66.5 μm, but experimentally is 27 μm. This difference is due to the high frequency vibration of pre-focusing mirror or monochromato. Nevertheless, high coherent hard X ray beams can be obtained at the location of experimental sample and many coherent experiments can be fulfilled on this beamline.
Numerical simulation of leaf-shaped metamaterial absorber at infrared frequency
Authors: Su Bin  , Gong Bo-Yi  , Zhao Xiao-Peng  ,   School of Science, Northwestern Polytechnical University, Xi'an 710129, China
Published: December 2020

We present a perfect metamaterial abosorber composed of metallic leaf-shaped cells, dielectric substrate and metallic film. Based on the metallic Drude principle, this structure can realize an perfect absorptivity of 99.5% at the infrared communication frequencies with appropriate geometric parameters. Moreover, this structure can simultaneously achieve perfect absorptions at two infrared frequencies with the maximal magnitudes of 99.67% and 97.13% respectively, which effectively broadens the bandwidth of absorptivity, thereby benefiting the design and the application of absorber at the infrared frequencies. Afterward, the effects of the neck width on the position of the double absorptivity peak are investigated, and expected to be used in frequency modulation. The model proposed in this paper has a series of advantages such as simple structure, high absorptivity and broad operating bandwidth.
Study of air-clad large-mode-area ytterbium doped photonic crystal fiber
Authors: Chen Gui  , Jiang Zuo-Wen  , Peng Jing-Gang  , Li Hai-Qing  , Dai Neng-Li  , Li Jin-Yan  ,   Wuhan National Laboratory for Optoelectronics, College of Optoelectronic Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
Published: December 2020

The Yb3+ doped double clad photonic crystal fiber (PCF) with a large core of around 90 m in diameter is prepared from SiO2-Al2O3-P2O5 core glass of an optical fiber preform through a conventional modified chemical-vapor deposition technique, solution doping and gas doping. The double clad PCF has a mode area of about 1330 m2. The core and inner cladding have numerical apertures of about 0.065 and 0.5, respectively. 1 m long photonic crystal fiber laser generates up to 102 W output power with a slope efficiency of 76%. Such lasers are potentially scalable to high power.
Optimization of phased array ultrasonic field in multi-medium
Authors: Ding Ya-Jun  , Qian Sheng-You  , Hu Ji-Wen  , Zou Xiao  ,   Institute of Image Recognition and Computer Vision, Hunan Normal University, Changsha 410081, China;,   College of Physics and Information Science, Hunan Normal University, Changsha 410081, China
Published: December 2020

According to the ultrasonic propagation characteristics in the multi-medium, a control method of ultrasonic focus in the multi-medium is presented through introducing the phase compensation factors and using genetic algorithm. The patterns of multi-focus ultrasonic field generated by two-dimensional phased array consisting of 1616 elements are simulated in multi-biological tissue, and the ultrasonic fields are calculated under the various thicknesses and the various absorption coefficients of medium layer. The results show that this approach can optimize the patterns of multi-focus ultrasonic field and restrain side-lobe, which can improve the ultrasonic intensity gain and make the maximal ultrasonic intensity focus on the target area. When the thickness and the absorption coefficient of biological tissue are changed, the focus position remains unchanged, but the ultrasonic intensity of the focus area will change relatively.
Characteristic analyses of high birefringence and two zero dispersion points photonic crystal fiber with octagonal lattices
Authors: Wang Wei  , Yang Bo  , Song Hong-Ru  , Fan Yue  ,   College of Automation, Harbin Engineering University, Harbin 150001, China
Published: December 2020

Aiming to the requirements of high birefringence and multiple zero dispersion points of optic-fiber sensing and communication systems, a new type of photonic crystal fiber (PCF) is proposed. The cladding is arrayed by octagonal air holes, and two big elliptical air holes are added in inner cladding to increase the birefringence. Numeral results show that this type of PCF exhibits high birefringence with a level of 10-3 when wavelength ranges from 0.8-2 m, which fulfils the requirement of high birefringence, and two zero dispersion points are obtained after optimization. In addition, high nonlinear coefficient with a level of 10-2 m-1W-1 is obtained, which could be used in the case where the nonlinearity is highly required.
Research on plasma axial velocity generated by small debris accelerator coaxial gun
Authors: Gao Zhu-Xiu  , Feng Chun-Hua  , Yang Xuan-Zong  , Huang Jian-Guo  , Han Jian-Wei  ,   Center for Space Science and Applied Research, Chinese Academy of Sciences, Beijing 100190, China;,   Institute of Physics, the Chinese Academy of Sciences, Beijing 100190, China
Published: December 2020

"Plasma driven micro-particle accelerator" is a ground device for simulating impact effects of small debris in space. The particle velocity is determined mainly by axial velocity of plasma in a coaxial gun. Emission spectrometry is used to study the plasma axial velocity at different voltages and gas pressures. The experimental results indicate that axial velocity increases with the increase of discharging voltage, and doesn't change significantly with the pressure of working gas, which is consistent with the result of numerical simulation. This result is useful to improve the plasma axial velocity further, and provides an experimental basis for optimizing the accelerator.
Properties and fabrication status of capsules for ignition targets in inertial confinement fusion experiments
Authors: Zhang Zhan-Wen  , Qi Xiao-Bo  , Li Bo  ,   Laser Fusion Research Center, China Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

The inertial confinement fusion program has proposed a laser capable of producing ignition and gain as the next step. Several choices exist in the design and production of capsules. In this paper the important features of each ablator material and the status of production are summarized. The design consists of ablators made of germanium-doped carbon hydrogen (CH), beryllium doped copper, polyimide, B4C and diamond. The CH and beryllium capsules are two of the most important choices. Compared with the beryllium shell, the CH shell has no microstructure and has a transparent wall that allows optical characterization of the fuel ice layer. The CH shell has the advantage that the specification can be easy to satisfy the ignition acquirements. The current ignition point has been designed in USA since 2010. The ignition target design has a series of demands for the capsule, such as capsule dimensions, coating density, void defects and volume, surface roughness, uniformity, doping and impurity levels. Now, the CH capsule can meet ignition requirements in USA, while the relevant work has just started in China.
Dual drag reduction mechanism of water-based dispersion with hydrophobic nanoparticles in core microchannel and experimental verification
Authors: Wang Xin-Liang  , Di Qin-Feng  , Zhang Ren-Liang  , Gu Chun-Yuan  , Ding Wei-Peng  , Gong Wei  ,   Shanghai Institute of Applied Mathematics and Mechanics, Shanghai University, Shanghai 200072, China;,   Shanghai Key Laboratory of Mechanics in Energy and Environment Engineering, Shanghai 200072, China
Published: December 2020

Dual drag reduction mechanisms of water-based dispersion with nanoparticle is proposed. A contrastive study is take to verify the mechanism, in which the changes of surface microstructure and wettabilities of the core slices take place before and after treating by dispersion with hydrophobic nanoparticles and scouring by water. The results show that the surface of core slice which is treated by water-based dispersion with hydrophobic nanoparticles has strong hydrophilic property, and a compact nanoparticle adsorption layer forms on it. The nanoparticle adsorption layer still exists after scouring, but the core slice surface is changed into strong/super hydrophobic, reflecting that the surfactants which are adsorbed on the nanoparticles adsorption layer surface are gradually cleaned. The water-based dispersion with hydrophobic nanoparticles are mainly manifested as the chemical surfactant drag reduction effect during initial injection. With the injection continued, the mechanical drag reduction induced by the slip effect of super hydrophobic surface is reflected mainly. Core displacement results show that the water-phase effective permeability could increase about 84.3% on average. The results strongly confirm the dual drag reduction mechanism of the water-based dispersion with hydrophobic nanoparticles.