bluuebunny/crossref_metadata_2025 huggingface dataset:
Shear modulus of aluminum under shock loading
Authors: Hu Jian-Bo  , Yu Yu-Ying  , Dai Cheng-Da  , Tan Hua  ,   中国工程物理研究院流体物理研究所，绵阳  621900
Published: December 2020

Steinberg-Cochran-Guinan (SCG) model, the corrected SCG model and the finite strain theory were reviewed with respect to the basic assumptions and applicability, and the shear modulus data of aluminum under shock compression predicted by these models were compared with the available data obtained in one-dimensional plate impact experiments. The comparison shows that the corrected SCG model is the best one,being capable of describing the variation of the measured shear modulus of aluminum with shock pressure, although the other two are applicable at lower pressure. It is found that the shear modulus increases gradually with the increase of shock pressure in the range of 10—80GPa due to the work-hardening effects. As the shock pressure goes above ～80GPa, the shear modulus of aluminum falls quickly due to the dominating effect of high-temperature softening, and when the shock pressure reaches ～125GPa， corresponding to the onset of melting on Hugoniot, the shear modulus of aluminum decreases to zero.
Investigation of phase instability in the binary Gaussian core model
Authors: Guo Yuan-Yuan  , Chen Xiao-Song  ,   华中师范大学粒子物理研究所，武汉  430079;中国科学院理论物理研究所，北京  100080
Published: December 2020

By considering the fluctuation of grand potential Ω around equilibrium with respect to small density fluctuations δρα(r), the phase instability of binary Gaussian core model has been investigated and characterized. The spinodal of this model is obtained by using its direct correlation functions calculated in the hypernetted chain(HNC) approximation. Our analysis shows that this phase transition is predominately demixing. The results in HNC approximation have been compared with that in the random phase approximation.
The dipolar interaction model of the molecular aggregation in Langmuir-Blodgett films
Authors: Han Kui  , Li Hai-Peng  , Wu Yu-Xi  , Shen Xiao-Peng  , Huang Zhi-Min  ,   中国矿业大学理学院，徐州  221008
Published: December 2020

Based on the classical electrostatics theory, the model of dipole-dipole interaction in the aggregation of rod-like amphiphilic molecules in Langmuir-Blodgett(LB)films has been presented in the paper. The relations between LB films structure and spectral absorption peak were obtained by using this model. For Z-type films, the dependence of molecular aggregation state on the structure parameters, i.e. separation distance a, separation between two adjacent layers d, molecular orientation θ, and layer number g, were studied by applying our model. The theoretical results agree well with experimental data.
Study on the influence of three-dimensional Cu(111) islands on the diffusion of adatom by molecular dynamics simulation
Authors: Tang Xin  , Zhang Chao  , Zhang Qing-Yu  ,   大连理工大学三束材料改性国家重点实验室,大连  116024
Published: December 2020

The adatom diffusion barriers on homoepitaxial three-dimensional (3D) Cu(111) islands with different numbers of monolayers have been studied by using molecular dynamics simulation combined with a molecular statics method. The parameter of atomic interaction potentials, which has been introduced in the embedded atom method, was applied in the simulation. The influence of 3D islands with different numbers of monolayers on the hopping diffusion and the exchange diffusion has been discussed in the paper. The results show that the two-dimensional (2D) Enrilich-Schwoebel (ES) barriers are lower than the 3D-ES barriers and the 3D-ES barrier is independent of the atomic layers in 3D islands. For the 3D island with (100) side-facet, the adatom diffusion along 〈011〉 will be affected by the number of monolayers in the 3D island. The adatom diffusion on the 3D islands is dominated by downward diffusion mechanism. For the 3D islands with the (111) side-facet, however, upward diffusion on the 3D islands is possible.
Theoretical research on critical thickness of HgCdTe epitaxial layers
Authors: Wang Qing-Xue  , Yang Jian-Rong  , Wei Yan-Feng  ,   中国科学院上海技术物理研究所,上海  200083
Published: December 2020

Based on the relationships between stress and strain in an arbitrary coordinate system, the elastic theory of crystal and the dislocation gliding theory, the critical thicknesses of HgCdTe/CdZnTe oriented in the ［111］ and ［211］ directions are calculated, and the dependence of the critical thickness of HgCdTe on substrate composition and film composition are studied. The results show that the critical thickness of HgCdTe depends sensitively on substrate composition and film composition. For 10μm films oriented in the ［111］ direction prepared by liquid phase epitaxy, the substrate composition and the films composition must match to within ±0.225‰ and ±5‰, respectively, to prevent the occurence of misfit dislocations. In addition, for 10μm films oriented in the ［211］ direction prepared by molecular beam epitaxy, the actual ranges of zinc composition and the films composition are ±0.2‰ and ±4‰ for the films to remain below the critical thickness, respectively.
First principle study on β-SiC(001)-(2×1) surface structure
Authors: Xu Peng-Shou  , Li Yong-Hua  , Pan Hai-Bin  ,   中国科学技术大学国家同步辐射实验室，合肥  230029
Published: December 2020

We calculate the atomic and electronic structure of β-SiC(001)-(2×1) using augmented plane wave and local orbital (APW+LO) method. The calculated results show that the atomic structure of β-SiC(001)-(2×1) surface can be described by symmetrical Si dimmer model, which is different from the asymmetrical Si dimmer model of Si(001)-(2×1) surface. The bond length of Si dimmer of β-SiC(001)-(2×1) surface is 0.269 nm, which is larger than that of Si(001)-(2×1) surface. The calculated results of electronic structure show that a prominent density of states exists at the Fermi level, so β-SiC(001)-(2×1) surface has the characteristics of metal. There are four surface state bands in the gap. Among them, two occupied surface state bands have been confirmed by valence band spectra of synchrotron radiation photoelectron spectroscopy.
Molecular dynamics study on the structural and thermodynamic properties of the zinc-blende phase of GaN at high pressures and high temperatures
Authors: Sun Xiao-Wei  , Chu Yan-Dong  , Liu Zi-Jiang  , Liu Yu-Xiao  , Wang Cheng-Wei  , Liu Wei-Min  ,   (1)兰州交通大学数理学院,兰州  730070; (2)兰州师范高等专科学校物理系,兰州  730070; (3)西北师范大学物理与电子工程学院,兰州  730070; (4)中国科学院兰州化学物理研究所固体润滑国家重点实验室,兰州  730070
Published: December 2020

The structural and thermodynamic properties of zinc-blende phase of GaN have been investigated systematically using the molecular dynamics method with Buckingham potential model. These properties including lattice constant, phase transition pressure (from the zinc-blende to the rock-salt structure), thermal expansion, isothermal bulk modulus, and heat capacity at constant pressure were calculated in a wide range of temperatures (300—3000K) and pressures (0—65GPa). The structural and thermodynamic parameters obtained under normal state are found to be in good agreement with the existing experimental and theoretical results. Meanwhile, some thermodynamic parameters such as isothermal bulk modulus and heat capacity at constant pressure have been predicted at elevated temperatures and high pressures based on the reliable potential model. The simulated results are of fundamental importance in material science.
The effect of size distribution on photoluminescence of excited states from InAs/GaAs quantum dots
Authors: Tang Nai-Yun  , Chen Xiao-Shuang  , Lu Wei  ,   中国科学院上海技术物理研究所红外物理国家重点实验室，上海  200083
Published: December 2020

We have used the effective mass approximation to calculate the effect of size non-uniformity on the width of photoluminescence (PL) emission peaks of the quantum dots (QDs). In order to investigate the variation in PL inhomogeneity of the energy levels, we have calculated the effects of small changes of the structural parameters on the energy spectrum. Theoretical calculations have shown that different size distributions effect differently on the width of the ground and excited states of QD. The distribution of height, as well as the diameter and the volume, appears to be the key parameter that controls the effective potentials in the vertical and lateral directions, and these two potentials change the sharpness of all PL peaks. This causes the line width of the higher energy levels to be either broader or sharper than that of the ground state, or in certain cases to be equal to the line width of the ground state.
Mechanism of low magnetic aging of Nd-Fe-B permanent magnet
Authors: Zhu Ming-Gang  , Li Xiu-Mei  , Guo Zhao-Hui  , Li Wei  ,   钢铁研究总院功能材料研究所,北京  100081
Published: December 2020

The irreversible flux loss (FL) of sintered Nd-Fe-B magnets has been investigated after aging for about 920 d. Exposed at room temperature (RT) and 353K, the values of FL are about 1.4％ and 13%, respectively. However, with a pre-aging the FL are about 6‰ and 6.9% for the magnets exposed at RT and 353K, respectively. Therefore, the stability of flux has been improved obviously by the pre-aging. A phenomenological formula, based on the Boltzmann statistics, has been used to discuss the effect of microstructure on FL. It is found that the experimental results can be well explained by the formula.
Fabrication and properties of the Y-doped Al2O3 high-k gate dielectric films
Authors: Guo De-Feng  , Geng Wei-Gang  , Lan Wei  , Huang Chun-Ming  , Wang Yin-Yue  ,   (1)兰州大学物理系，兰州  730000; (2)兰州大学物理系，兰州  730000;燕山大学物理系，秦皇岛  066004
Published: December 2020

Y-doped Al2O3 dielectric films have been fabricated by reactive radio frequency co-sputtering method. Grazing angle incidence x-ray diffraction results show that the as-deposited and annealed films are amorphous. High resolution scanning electron microscope and atomic force microscope have been applied to observe the cross-section and the surface morphology of the thin films. The electric C-V and I-V characteristics were measured at high and variable frequency, respectively. It was found that the dielectric constant k of the films increases remarkably (from 8.14 to 11.8) with increasing Y-doping concentration. The Y—O bond is stronger than Al—O due to the obvious difference in electro-negativity between the two bond members, which enhanced the ionic polarization in the thin films leading to an increase of the dielectric constant. It was supposed that the presence of Y ions changed the structure and atomic coordination of Al2O3. The films were very smooth which meet the requirements of the device.
Determination of optical parameters of ordered Ag/AAO nano-array composite structure
Authors: Wang Jian  , Wang Cheng-Wei  , Li Yan  , Liu Wei-Min  , Shigeaki Zaima  ,   (1)名古屋大学结晶材料科学系，日本名古屋  464-8603; (2)西北师范大学物理与电子工程学院,兰州  730070; (3)中国科学院兰州化学物理研究所固体润滑国家重点实验室,兰州  730070
Published: December 2020

The optical transmission function is modified by taking account of the influence of thickness variation Δd on transmission of thin films. Meanwhile, we introduce an optimization technique and define an evaluating function, such that a simple method is developed based on the envelope curves of the optical transmission spectrum over the wavelength range 500—2700nm at normal incidence, which is used for the determination of the equivalent refractive index n, equivalent extinction coefficient k, average equivalent thickness d and thickness variation Δd of the ordered Ag/AAO nano-array composite structure. The relative error is about 0.3% in the calculation of average equivalent thickness . The simulated transmission of Ag/AAO nano-array composite structure is in satisfactory agreement with the measuremental values. All these results show that with this simple method the optical parameters of Ag/AAO nano-array composite structure can be calculated of accurately and the results are consistent with the experiment.
Yang Hui Triangle symmetry and higher-order differential equations of motion
Authors: Shi Yong  , Ma Shan-Jun  ,   江西师范大学物理与通讯电子学院，南昌  330027
Published: December 2020

In this paper, by using Mathematica software to disclose the relationship between partial derivative and high-order derivative of different variables in the function r=r(q(t),t), the symmetry of Yang Hui Triangle of the function r=r(q(t),t) is discovered. Combining the symmetry of Yang Hui triangle with the Newtonian second law, the high-order differential equations of motion are deduced. Finally the high-order differential equations of systems under ideal constraints are discussed.
The simulation study of spherics and red sprite phenomenon produced by lightning
Authors: Wu Ming-Liang  , Xu Ji-Yao  , Ma Rui-Ping  ,   (1)空间天气学重点实验室，中国科学院空间科学与应用研究中心，北京  100080; (2)空间天气学重点实验室，中国科学院空间科学与应用研究中心，北京  100080;中国科学院研究生院，北京  100039
Published: December 2020

By using a two-dimensional, time-dependent electromagnetic field model (EM model), the spherics and red sprite phenomenon is studied. The simulation results show that the total electric fields produced by lightning include radiation field and quasi-electrostatic field (QEF). The spherics result from the radiation field, which propagates within the earth-ionosphere waveguide. The optical emissions of the first positive band of N2 caused by the QEF form the red sprite phenomenon. By means of simulation we have found the red sprite apparently appearing in “V” shape during its evolution and a bright nucleus existing within the structure of the red sprite, while the brightness of the exterior of the red sprite, which is referred to as sprite halo, being relatively weaker.
A family quasi-distribution function representation in phase space
Authors: Yuan Tong-Quan  ,   北京理工大学理学院物理系,北京  100081
Published: December 2020

A family quasi-distribution function representation is defined in this article. This family quasi-distribution function representation is constructed from the family wave function of the Schrdinger equation in phase space in which the definitions of the operators are α=αp-i?q and α=(1-α)q+i?p. Two interesting relationships are found. The first one is that the family wave function of the Schrdinger equation in phase space is a “Window” Fourier transform of the function φ(λ)exp［i(1-α)qp/?］. The second one is that different choices of the window functions result in different distribution functions. When the window function g(λ) is a Gaussian function the distribution function is the Husimi-like distribution function. When the window function g(λ) is a plural function representing an ellipse, the quasi-distribution function is the Ellipse distribution function; and finally when the plural function g(λ) is supplemented with the additional condition α=0, it will result in the standard ordering, anti-standard ordering distribution function and Wigner function. In this case g(λ) is a function depieting a rectangular window with width λ and height 1/12π?.
Experimental generation of bright green light in amplitude-squeezed state via extracavity frequency doubler
Authors: Li Ying  , Luo Yu  , Pan Qing  , Peng Kun-Chi  ,   山西大学光电研究所，量子光学与光量子器件国家重点实验室，太原  030006
Published: December 2020

Bright green light in the amplitude-squeezed state is experimentally generated from a frequency doubler with semi-monolithic F-P configuration consisting of an a-cut type-Ⅱ KTP crystal and a concave mirror. The amplitude-squeezing of 3.1±0.2dB at 540nm wavelength is obtained with the pump power of 50mW under the conditions of the two infrared modes in resonance and the green mode nearly in resonance.
The collision problem of one kind of methods for constructing one-way Hash function based on chaotic map
Authors: Wang Ji-Zhi  , Wang Ying-Long  , Wang Mei-Qin  ,   山东省计算中心，济南  250014
Published: December 2020

Chaos would happen within certain ranges of parameters of chaotic system. The chaos sequence has good pseud random character. Now some papers have provided some methods to construct one-way hash function based on chaotic map. Through analyzing these methods, the appearance of collision is proved. So some key problems are pointed out which should be taken care of while constructing one-way function based on chaotic map.
Directing chaos systems towards low-period motion based on adaptive pulse perturbation
Authors: Zhang Rong  , Xu Zhen-Yuan  ,   江南大学理学院信息与计算科学系，江苏无锡  214122
Published: December 2020

A method is presented here to direct two or many chaotic systems towards low-period motions by using adaptive pulse perturbation method. Many chaotic systems can be controlled to different periodic orbits simultaneously. When the same input state variable of the adaptive pulse perturbation is used, two or more chaotic systems can be controlled to different periodic synchronizations. Simulation shows that the R?ssler chaotic system can be stabilized to different periodic orbits by using the method, which verifies its effectiveness.
Chaos control of a modified coupled dynamos system
Authors: Wang Xing-Yuan  , Wu Xiang-Jun  ,   大连理工大学电子与信息工程学院，大连  116024
Published: December 2020

This paper studies the problem of control ling the chaotic behavior of a modified coupled dynamos system. Two different methods, namely the feedback and non-feedback methods are used to control chaos in the modified coupled dynamos system. Based on the Lyapunov direct method and Routh-Hurwitz criteria, the conditions of suppressing chaos to unstable equilibrium points or unstable periodic orbits (limit cycles) are discussed, and they are proved theoretically. Numerical simulations show the effectiveness of the two different methods.
Synchronizing erbium-doped fiber dual-ring lasers by using the method of feedback modulating-parameter
Authors: Fan Wen-Hua  , Tian Xiao-Jian  , Yu Yong-Li  , Chen Ju-Fang  , Luo Hong-E  ,   (1)吉林大学电子科学与工程学院，长春  130012; (2)吉林大学电子科学与工程学院，长春  130012;东北师范大学物理学院，长春  130024
Published: December 2020

A method of feedback modulating-parameter is presented to synchronize hyperchaotic systems, and is applied to the hyperchaotic erbium-doped fiber dual-ring laser systems. A circuit is designed in the laser synchronization system to avoid phase-vagueness automatically. Numerical simulation shows that two hyperchaotic erbium-doped fiber dual-ring lasers can be identically synchronized, when the feedback intensity is suitably selected.
The upconversion luminescent of Er3+/Yb3+ co-doped ZrO2-Al2O3 powders
Authors: Ding Qing-Lei  , Xiao Si-Guo  , Zhang Xiang-Hua  , Xia Yan-Qin  , Liu Zheng-Wei  ,   (1)现代物理研究所,湘潭大学材料与光电物理学院，湘潭  411105; (2)现代物理研究所,湘潭大学材料与光电物理学院，湘潭  411105;先进材料及其流变特性教育部重点实验室，湘潭  411105
Published: December 2020

Samples of Er3+/Yb3+ co-doped ZrO2-Al2O3 powders were prepared by solid-state reaction. The upconversion luminescence spectrum excited by 980 nm laser light suggests that there exit three main emission bands: one red emission band centered at 654 nm and two green emission bands centered at 545 and 525nm, corresponding to Er3+ ions transitions of 4F9/2→4I15/2, 4S3/2→4I15/2 and 2H11/2→4I15/2, respectively. The emission band centered at 654 nm is much stronger than the other two. The upconversion mechanisms are discussed and it is found that both red emission and green emissions are two-photon processes. It can be seen from the XRD spectra that zirconia (ZrO2) mainly exists as a cubic phase,while Al3+ is implanted into the ZrO2 lattice, producing the ZrO1.87. The solid solution towers the site symmetry of the lattices in ZrO2 crystals, which promotes the upconversion efficiency.
J/ψ anomalous suppression in high-energy heavy-ion collisions
Authors: Li Qiang  , Jiang Zhi-Jin  , Xia Hong-Fu  ,   上海理工大学理学院，上海  200093
Published: December 2020

We have analyzed the experimental data obtained by NA50 Collaboration in Pb-Pb collisions at 158A GeV/c. By assuming the QGP phase transition in central Pb-Pb collisions and its 100% suppression to J/ψ, we correct the differential cross section of J/ψ production in high-energy heavy-ion collisions based on the theory of J/ψ absorption by nucleons and comovers. The theoretical result fits the experimental data well.
Flipped symmetry potential in heavy-ion collisions
Authors: Yong Gao-Chan  , Li Bao-An  , Chen Lie-Wen  , Zuo Wei  ,   (1)Department of Chemistry and Physics,P.O.Box 419,Arkansas State University,Arkansas 72467-0419,USA; (2)上海交通大学理论物理研究所，上海  200240; (3)中国科学院近代物理研究所，兰州  730000; (4)中国科学院近代物理研究所，兰州  730000;中国科学院研究生院，北京  100049
Published: December 2020

Within the IBUU transport model, flipping of the symmetry potential in heavy-ion collisions is studied. It is found that there exist flipping of the symmetry potential in the isospin fractionation, the single neutron to proton ratio, the double neutron to proton ratio and the neutron-proton differential flow from lower to higher incident energies. The flipping of the symmetry potential results from the change of the relative magnitude of the hard and soft symmetry energies at lower and higher densities. Future observations of the flipped symmetry potential in experiment will help the study of the density-dependent symmetry energy.
Structural phase transformation and optical absorption of capped TiO2 nanoparticles
Authors: Cui Yong-Feng  , Yuan Zhi-Hao  ,   天津理工大学纳米材料与技术研究中心,天津  300191
Published: December 2020

TiO2 nanoparticles capped with a layer surfactant were prepared by colloid-chemical method, and their structural phase transformation and optical absorption properties were investigated. XRD and TEM results showed that the surfactant capping effectively inhibits the grain growth during heat-treatment, and results in a different crystallization behavior in which titania nanoparticles with amorphous structure can simultaneously transform into anatase and rutile when heat-treated below 400℃. It was found from optical absorption measurement that the capped TiO2 colloidal particles in toluene sol have a large red shift of absorption band edge in contrast with that without capping, which is mainly attributed to the effects of the interface dipole and dielectric confinement. In the investigation of the relation between the absorption coefficient and photon energy, it was found that there exist two linear correspondences of (αhν)1/2 vs hν(indirect transition) and (αhν)2 vs hν (direct transition) for the titania films and colloidal-particle organic sol. The respective band gap values were obtained by extrapolation of the above linear relation.
Experimental and theoretical study on the optimization of the normalized heating parameter in the operating LD side-pumped Nd:YAG ceramic lasers
Authors: Zhu Hong-Tao  , Lou Qi-Hong  , Qi Yun-Feng  , Dong Jing-Xing  , Wei Yun-Rong  ,   中国科学院上海光学精密机械研究所，上海  201800
Published: December 2020

The suppressing effect of laser extraction on the non-radiation transition process is taken into account when the heat model of gain media is developed. Based on the developed heat model, the heat generation in the operating LD side-pumped Nd:YAG ceramic lasers is quantified through using the normalized heating parameter, which can be deduced from the experimental results of the slope efficiency and the absorbed pumping power of the gain media. The main factors which influence on the heat generation are investigated by studying the normalized heating parameter, and the results show that the changes of the laser extraction efficiency, the beam overlap efficiency and the Nd3+ concentration will result in obvious variations of the normalized heating parameter. In this work, the laser extraction efficiency increases to 0.905 by the optimization of the transmission of the output coupling, and the normalized heating parameter decrease to 0.474, correspondingly.
Influence of diffusion on the interaction between photovoltaic spatial solitons
Authors: Yan Li-Fen  , Wang Hong-Cheng  , She Wei-Long  ,   中山大学光电材料与技术国家重点实验室，广州  510275
Published: December 2020

We numerically investigate the impact of diffusion field in photovoltaic photorefractive crystals on the interaction between two coherent photovoltaic spatial solitons. Numerical simulations show that the in-phase interaction will result in the separation of the two solitons from each other, accompanied by the energy coupling between the beams, which is different from the case without diffusion field. And for the case of interaction out of phase, the two solitons are no longer the simply separated. Under certain conditions, they are exclusive to each other but deflect simultaneously to the same side.
Effects of nonideal characteristics of chirped fiber grating dispersion compensators on the system with different modulation formats
Authors: Chen Yong  , Liu Yan  , Cao Ji-Hong  , Tan Zhong-Wei  , Jian Shui-Sheng  ,   北京交通大学光波技术研究所，北京  100044
Published: December 2020

The causes leading to the nonideal characteristic of the chirped fiber Bragg grating (CFBG ) are discussed. The impact of the group delay ripple (GDR), reflectivity ripple (RR) and bandwidth of the CFBG on the 10Gb/s transmission system where non-return-to-zero (NRZ), return-to-zero (RZ) and carrier-suppressed return-to-zero (CSRZ) formats was investigated and the CFBG employed as dispersion compensator was simulated and compared in detail. The analytical result helps to optimize the practical 1500km CFBG-based transmission and the relation between the system performance and the nonideal characteristic of the grating validated the analysis in this paper.
Velocity slip of liquid flow in nanochannels
Authors: Cao Bing-Yang  , Chen Min  , Guo Zeng-Yuan  ,   清华大学工程力学系，北京  100084
Published: December 2020

Molecular dynamics simulations are carried out to investigate the velocity slip phenomenom of liquid flow in nanochannels. The liquid is argon, and the wall is taken to be platinum or its model solids. The effect of the surface wettability on the velocity slip is obtained through varying the potential interaction strength between the liquid and the wall. The simulation results show that the liquid adjacent to a hydrophilic surface is solid-like and has high density and orderliness. However, the liquid near a hydrophobic surface forms a gap of low density. The velocity slip of the liquid flow over solids decreases with the increasing interaction strength between the liquid and the channel surface. The slip, the no-slip and the negative slip are all possible to take place for different liquid-surface wettabilities. We find that the apparent slip of the liquid flow over solids is affected by the integrated factors of boundary slip, liquid sticking and liquid-internal slip.
Measurements of angular distribution and energy spectrum of hot electrons
Authors: Zheng Zhi-Yuan  , Li Yu-Tong  , Yuan Xiao-Hui  , Xu Miao-Hua  , Liang Wen-Xi  , Yu Quan-Zhi  , Zhang Yi  , Wang Zhao-Hua  , Wei Zhi-Yi  , Zhang Jie  ,   (1)中国科学院物理研究所光物理重点实验室，北京  100080; (2)中国科学院物理研究所光物理重点实验室，北京  100080;中国科学院西安光学精密机械研究所瞬态光学技术国家重点实验室，西安  710068
Published: December 2020

The angular distribution and energy spectrum of hot electrons produced in the interaction of ultra-short ultra-intense laser pulses with solid foil targets are investigated. Results show that bath the angular distribution and the energy spectrum reveal anisotropic behavior. This anisotropy is believed to be related to the electron generation mechanism. The existence of energy anisotropy explains why different experimental groups obtained quite different elctron temperatures under the same laser intensity.
Study on the formation of square emission pattern in argon discharge
Authors: Dong Li-Fang  , Fan Wei-Li  , Li Xue-Chen  , Gao Rui-Ling  , Liu Fu-Cheng  , Li Shu-Feng  , He Ya-Feng  ,   河北大学物理科学与技术学院，保定  071002
Published: December 2020

Stable square emission patterns are observed in argon discharge at atmospheric pressure by using a dielectric barrier discharge device with different lateral boundary conditions. The spatio-temporal dynamics of square pattern in nanosecond time scale is investigated. It is found that the square pattern is an interlacing of two oscillating square sublattices, which have time sequence inversion behavior. The influence of the wall charge distribution on the forming process and the spatio-temporal dynamics of the emission patterns is discussed.
Field emission from ZnO nanorods
Authors: Ni Sai-Li  , Chang Yong-Qin  , Long Yi  , Ye Rong-Chang  ,   北京科技大学材料科学与工程学院,北京  100083
Published: December 2020

The field emission properties of the randomly oriented and the well-aligned ZnO nanorods synthesized by a thermal evaporation method were investigated in detail. It was found that the field emission of the well-aligned ZnO nanorods is seriously affected by the screening effect. While, compared with the ZnO arrays, the field emission measurements on the randomly oriented ZnO nanorods show a lower turn-on filed and a larger field enhancement factor, which are attributed to the weak screening effect and the surface perturbations. These features make the random ZnO nanorods as a competitive candidate for field emission flat panel display.
Influence of working pressure on the crystallinity and growth behavior of ZnO films deposited by reactive radio-frequency magnetron sputtering
Authors: Liu Zhi-Wen  , Gu Jian-Feng  , Fu Wei-Jia  , Sun Cheng-Wei  , Li Yong  , Zhang Qing-Yu  ,   大连理工大学三束材料改性国家重点实验室,大连  116024
Published: December 2020

Using the reactive radio-frequency magnetron sputtering method, ZnO films were deposited on Si (001) and quartz substrates at different pressures with a fixed flow ratio of Ar to O2. The influence of working pressure on the crystallinity and growth behavior were studied with the help of characterization of the morphology, microstructure and optical properties of the films by atomic force microscopy (AFM), X-ray diffraction (XRD), transmission electron microscopy (TEM) and transmittance spectra,respectively. It is found that a critical working pressure can be taken as 0.5—1.0 Pa. With increasing the working pressure from 0.1 Pa up to the critical working pressure, the density of ZnO grains decreases and the films have high c-axis orientation with strong in-plane textured feature. When the working pressure exceeds the critical working pressure, the density of ZnO grains is roughtly a constant and the in-plane textured feature disappears. The influence of working pressure on the refractive index, extinction coefficient and optical energy gap is also discussed in the paper.
Preparation nanostructured FeAl2O4-Al2O3-Fe composite coating by SHS plasma spraying technology
Authors: Niu Er-Wu  , Yan Dian-Ran  , He Ji-Ning  , Dong Yan-Chun  , Li Xian-Zhi  , Feng Wen-Ran  , Zhang Jian-Xin  , Zhang Gu-Ling  , Yang Si-Ze  ,   (1)河北工业大学材料学院，天津  300132; (2)河北工业大学材料学院，天津  300132;中国科学院物理研究所，北京  100080; (3)中国科学院物理研究所，北京  100080
Published: December 2020

In this paper, composite coating (about 400 μm thick) was prepared by SHS plasma spraying technology using micro-dimensional Fe2O3-Al composite feedstock, which was fabricated by mechanical glomeration. The composition and microstructure of the coating were analyzed by X-Ray diffraction, scanning electron microscopy and transmission electron microscopy. Meanwhile, the microhardness, fracture toughness and wear resistance were also measured. It shows that the skeleton of the coating is mainly composed of nanostructured FeAl2O4 and Al2O3, and the dispersed phase is nanosized Fe. The composite coating possesses satisfactory microhardness of about Hv870. Compared with conventional alumina coating, the fracture toughness and wear resistance of composite coating are increased by one and 1.5 times, respectively.
Effects of excessive Zn on the thermoelectric properties of β-Zn4Sb3
Authors: Qi Qiong  , Tang Xin-Feng  , Xiong Cong  , Zhao Wen-Yu  , Zhang Qing-Jie  ,   武汉理工大学材料复合新技术国家重点实验室，武汉  430070
Published: December 2020

Single-phase β-Zn4Sb3 bulk sample and several samples based on β-Zn4Sb3 with different amounts of Zn were produced by melting in an evacuated quartz ampoule followed by slow cooling and their thermoelectric properties were investigated at 300 to 700K. The distribution of Zn in the samples was observed and the effects of excess of Zn on thermoelectric properties of β-Zn4Sb3 compound were investigated systematically. With the amount of Zn increasing, electrical and thermal conductivities of the sample increase, and the Seebeck coefficient declines. The excess of Zn leads to an obvious improvement to the power factor of the β-Zn4Sb3 based materials. The ZTmax of the sample is 1.10 at 700K when the amount of excessive Zn is 2at%.
Molecular dynamic simulation of shock-induced phase transformation in single crystal iron with nano-void inclusion
Authors: Cui Xin-Lin  , Zhu Wen-Jun  , Deng Xiao-Liang  , Li Ying-Jun  , He Hong-Liang  ,   (1)中国工程物理研究院流体物理研究所冲击波物理与爆轰物理重点实验室，绵阳  621900; (2)中国工程物理研究院流体物理研究所冲击波物理与爆轰物理重点实验室，绵阳  621900;四川大学物理科学与技术学院，成都  610064; (3)中国矿业大学(北京)，北京  100083; (4)中国矿业大学(北京)，北京  100083;中国工程物理研究院流体物理研究所冲击波物理与爆轰物理重点实验室，绵阳  621900
Published: December 2020

Shock-induced phase transformation (body-centered cubic α phase to hexagonal close-packed ε phase) in single crystal iron with a nano-void inclusion has been investigated by means of molecular dynamic (MD) simulation. The simulated sample is 17.2nm×17.2nm×17.2nm in size with 428341 atoms, and in the center of the sample settled a void of 1.12nm in diameter. The shock wave compression is generated by using a piston impact with the sample at velocities of 350m/s, 500m/s and 1087m/s, respectively. Shock wave propagates along the ［100］ direction in the sample. Results indicate that the existence of void is an important factor for inducing the phase transformation, which initially occurs around the void and mainly on the (011) and (011) planes, while with the increase of compression time it expands to the rest of the sample. By analyzing the moving history of atoms under shock wave compression, the phase transformation mechanism has been outlined. It is found that when the atoms at (011) planes slide to the void along ［011］ direction, they may have relatively different displacement, such that results in alternative positions compared to their initial location and yields the new structure (hcp).
The localized properties of electronic states and conductivity of DNA sequence
Authors: Liu Xiao-Liang  , Xu Hui  , Ma Song-Shan  , Deng Chao-Sheng  , Guo Ai-Min  ,   中南大学物理科学与技术学院，长沙  410083
Published: December 2020

According to the tight-binding model of the single electron, we establish a one-dimensional random binary solid model for DNA molecules. Using the transfer-matrix approach, we calculate numerically the localization length and the conductivity of a DNA sequence with 50000 nucleotides base pairs. The results show that the random DNA sequence is an insulator with very small conductivity, that the localization length and conductivity strongly depend on energies, and there exist greater localization lengths at the band center than at the band edge, which implies there is higher conductivity at the band center. The results also show the localization lengths are affected by disorder degrees to some extent and decrease with the increasing of the degree of disorder for all energies. Especially with finite-size DNA sequence, the localization length and conductivity have obvious effect on nucleotide base pairs’ mol percentage.
Explicit and exact solutions to the variable coefficient combined KdV equation with forced term
Authors: Lu Dian-Chen  , Hong Bao-Jian  , Tian Li-Xin  ,   江苏大学非线性科学研究中心，镇江  212013
Published: December 2020

By constructing two new Riccati equations and using the generalized Riccati method, we simplified the form and enriched the general results.Using Mathematica software, exact solutions of the variable coefficient combined KdV equation with forced term are obtained, including many kinds of solitary-wave-like solutions,guasi-periodical solutions and solitary wave solutions with variable speed.
Dynamical phase changes of the self-trapping of Bose-Einstein condensates and its characteristic of entanglement
Authors: Ma Yun  , Fu Li-Bin  , Yang Zhi-An  , Liu Jie  ,   (1)北京应用物理与计算数学研究所,北京  100088; (2)济南大学理学院,济南  250022
Published: December 2020

In this paper, we exploit two-mode model to investigate the influence of quantum fluctuation on the self-trapping of the Bose-Einstein Condensate(BEC). We found that, even for the finite number of particles, the transition to self-trapping is still observed.In particular, because of the quantum fluctuation due to the finite number of particles, the critical phenomenon becomes fuzzily: the smaller the number of particles is, the more obviously fuzzily the critical phenomenon becomes. Quantum entanglement entropy is then introduced to depict the critical behavior near the transition point.
Quantification description of the chaotic PWM spectrum of the switching converter
Authors: Yang Ru  , Zhang Bo  ,   (1)华南理工大学电力学院,广州  510640; (2)华南理工大学电力学院,广州  510640;广州大学物理与电子工程学院，广州  510006
Published: December 2020

EMI of the switching-converter is decided by the spectrum of the PWM waveform. There is great theoretical and practical meaning to quantify and analysis them. This paper takes the PWM drive waveform as a time series of processes or events. Based on the analysis of the periodic frequency- spreading, statistical theory is applied to analyze the probability density function, characteristic function, invariable distribution and power spectral density of the PWM waveform under chaotic frequency-spreading, the characteristics of chaotic frequency-spreading are obtained. Finally, some feasible experiments are carried out which verified that the EMI of the switching converters is suppressed effectively by chaotic frequency-spreading.
Multi-scroll high-order general Jerk circuits
Authors: Liu Ming-Hua  , Yu Si-Min  ,   (1)广东工业大学自动化学院，广州  510090; (2)广东工业大学自动化学院，广州  510090;井冈山学院物理系，吉安  343009
Published: December 2020

This paper proposes a novel circuit design and implementation approach of generating multi-scroll chaotic attractors from high-order Jerk systems. According to high-order Jerk equations, multi-scroll high-order general Jerk circuits are designed by constructing a sequence of step functions with parameter control. The prominent feature for this kind of circuit design method is self-unified and in a sense universal. Based on the uniform circuit, both forth-order and fifth-order general Jerk circuits can be realized with the switching control. The switch set is also used to control the number of scrolls. Finally, the computer simulations and hardware implementations are given to generate multi-scroll chaotic attractors on the forth-order and fifth-order general Jerk circuits.
Experimental investigation on wavelength-tunable chaos generation and synchronization
Authors: Sang Xin-Zhu  , Yu Chong-Xiu  , Wang Kui-Ru  ,   北京邮电大学电子工程学院,北京 100876
Published: December 2020

Fundamental principles of high-frequency chaos generation and synchronization in Er-doped fiber ring lasers are analyzed. The experimental configuration for generating wavelength-tunable chaos is proposed, and high-frequency chaotic lasers at different wavelengths are generated. Synchronization between the chaos generated in the receiver laser and the chaos transmitted over 1 km that is generated in the transmitter laser are achieved, which paves the way for constructing the high speed secure chaos communication network.
Period-doubling bifurcation of stochastic Duffing one-sided constraint system
Authors: Feng Jin-Qian  , Xu Wei  , Wang Rui  ,   (1)陕西师范大学数学系，西安  710062; (2)西北工业大学理学院应用数学系，西安  710072
Published: December 2020

The conditions of constraint are treated by means of the mean constraint plane and the mean jump equation, in which the method of the Chebyshev polynomial approximation, previously used to explore period-doubling bifurcation of stochastic smooth systems, is applied to stochastic non-smooth systems. Numerical simulations show that period-doubling bifurcation exists in stochastic Duffing one-sided constraint system just as in smooth stochastic Duffing system, and furthermore, the Chebyshev polynomial approximation is an effective method in exploring the dynamical behavior of stochastic non-smooth system.
The experimental investigation of orbital angular momentum of complex astigmatic elliptical beams
Authors: Dong Yi-Ming  , Xu Yun-Fei  , Zhang Zhang  , Lin Qiang  ,   浙江大学物理系光学研究所，杭州  310027
Published: December 2020

Complex astigmatic elliptical beams possess very high orbital angular momentum. This kind of beams has important applications in many fields, such as atomic physics and biology. An experimental method of optical torsion balance to measure the orbital angular momentum of the beams is presented in this paper. In our experiment, the absorption slice rotates under the irradiation of the beam. The angular momentum of beams is obtained by measuring the rotation angle of the absorption slice. The angular momentum of complex astigmatic elliptical beam with different parameters is measured in this paper. The dependences of orbital angular momentum on the parameters of the elliptical beams are investigated. The experimental results are consistent with the theoretical predictions.
Improved nuclear density model and the nuclear effect in P-A Drell-Yan process
Authors: Gao Yong-Hua  , Zhao Zhi-Heng  , Hou Zhao-Yu  , Cao He-Fei  , Duan Chun-Gui  , He Zhen-Min  ,   (1)河北师范大学物理学院, 石家庄  050016; (2)石家庄铁道学院数理系, 石家庄  050043; (3)石家庄信息工程职业学院，石家庄  050035; (4)石家庄学院物理研究所, 石家庄  050801; (5)石家庄学院物理研究所, 石家庄  050801；河北师范大学物理学院, 石家庄  050016
Published: December 2020

In this paper we present an improved nuclear density model. We have found the nuclear effect parameters’ formula RAV(x,Q2) and RAS(x,Q2) for the valence quark distribution and sea quark distribution in the nucleus, in which we have used the relation between the nuclear density and the mean binding energy in nucleus. By using the model, we can well explain the experimental data of the of Drell-Yan process in P-A.
Study on the electromagnetic and absorption properties of the mixture filled with carbon coated EPS
Authors: Liu Shun-Hua  , Cui Xiao-Dong  , Zhao Yan-Bo  ,   大连理工大学材料科学与工程学院，大连  116024
Published: December 2020

Using the carbon coated expanded polystyrene (EPS) beads as filling admixture, the electromagnetic (EM) wave absorber more moistureproof and environment adaptive than the conventional absorber used in anechoic chamber was fabricated. The effective permittivity of the mixture with carbon volume content 1% was calculated by the strong fluctuation theory combining with Maxwell-Wagner theory; and the EM wave absorbing property of a laminated model filled with carbon coated EPS beads was predicted through calculation. Comparison with the experiment indicated that the results of calculation accorded with the experiment closely, and can be used for the design of the moistureproof EM wave absorber.
Resonance effect on a coaxial vircator
Authors: Luo Xiong  , Liao Cheng  , Meng Fan-Bao  , Zhang Yun-Jian  ,   (1)西南交通大学电磁场与微波技术研究所，成都  610031; (2)西南交通大学电磁场与微波技术研究所，成都  610031；中国工程物理研究院应用电子学研究所，绵阳  621900; (3)中国工程物理研究院应用电子学研究所，绵阳  621900
Published: December 2020

Some experiments at Institute of Applied Electronics of CAEP showed that the interaction between the virtual cathode oscillator and the cavity is a key factor in determining the output microwave power and propagating modes. Particularly, we observed that the E-beam plays an important role in the cavity formation. The experiments have been carried out with 350 kV diode voltage and 23 kA diode current, where pulsed microwaves of 500 MW in peak power and 3.3 GHz in frequency have been obtained. The energy conversion efficiency from the electron beam to microwave is about 6.2%, and the output microwave modes are mainly the TM01 mode and TE11 mode. The cavity resonance effect on a coaxial virtual cathode oscillator has been investigated in detail.
The effect of counting rate and time resolution on the measured photon statistical properties—— Experimental study of direct measurement via SPCM
Authors: Li Yuan  , Li Gang  , Zhang Yu-Chi  , Wang Xiao-Yong  , Wang Jun-Min  , Zhang Tian-Cai  ,   量子光学与光量子器件国家重点实验室，山西大学光电研究所，太原  030006
Published: December 2020

Photon statistical properties of coherent field and thermal field are experimentally studied by means of direct photon counting using only one single-photon-counting module (SPCM) operating in Geiger mode. The second-order degree of coherence as affected by photon counting rate and selected resolution time is investigated systematically. By taking into account all the experimental factors which can influence the g(2), the second-order degree of coherence of an unknown optical field can be determined quickly and simply via single SPCM when choosing proper detecting conditions. In our experiment, when the counting rate is about 109 kc/s and the resolution time varies from 28 ns to 212 ns, the measured results can reliably reflect the different second-order degree of coherence of coherent and thermal fields.
Design of left-handed microstrip based on DGS and double layers SRRs structures
Authors: Wu Ming-Feng  , Meng Fan-Yi  , Wu Qun  , Wu Jian  ,   (1)哈尔滨工业大学电子与信息技术研究院，哈尔滨  150001; (2)哈尔滨工业大学电子与信息技术研究院，哈尔滨  150001；电波环境特性及模化技术国家重点实验室，北京  102206
Published: December 2020

A double band left-handed (LH) microstrip is designed based on defected ground structure (DGS) and Split Ring Resonators (SRRs) with broad bandwidth and low loss while the size of the unit cell is small and the synthesis is simple. Its effective permittivity and permeability are both extracted from the transmission and reflection data of the left-Handed microstrip, then the wave number k is calculated, and the results demonstrate that the LH microstrip shows backward wave (BW) properties in the broad frequency range of interest.
Application of the equivalence principle and the reciprocity theorem to electromagnetic scattering from two adjacent spherical objects
Authors: Guo Li-Xin  , Wang Yun-Hua  , Wu Zhen-Sen  ,   西安电子科技大学理学院,西安  710071
Published: December 2020

Based on the equivalence principle and the reciprocity theorem, the problem of electromagnetic scattering from two adjacent objects is considered and a solution that accounts for multiple scattering up to second-order is evaluated. In general, the first-order solution can easily be obtained by calculating the scatted field from isolated targets when illuminated by a plane-wave. However, due to the difficulty in formulating the coupled scattering field, it is impossible to find an exact analytical solution for the second-order scattered field. In this work, the second-order solution of electromagnetic scattering from two adjacent conducting/dielectric objects is derived by employing the reciprocity theorem and this solution is simplified from volume integral to surface integral form by using the equivalence principle. Meanwhile, the relation between the secondary scattering field from one target and the other is derived. Finally, the composite scattering field from two adjacent spheres is calculated using the formulas obtained in this work. The bistatic scattering pattern is discussed and the results are compared with numerical computations based on Time Domain Integral Equation Method (TDIEM).
Improving of the irradiation uniformity on targets with a diffraction-weakened lens array and spectral dispersion smoothing
Authors: Jiang Xiu-Juan  , Zhou Shen-Lei  , Lin Zun-Qi  , Zhu Jian  ,   (1)中国工程物理研究院上海激光等离子体研究所，上海  201800; (2)中国科学院上海光学精密机械研究所高功率激光物理国家实验室，上海  201800
Published: December 2020

A scheme employing a lens array and the technique of smoothing by spectral dispersion is presented for uniform irradiation on targets in inertial confinement fusion. Quasi-near field spots with a profile of sharp edge and flat top can be obtained with a diffraction-weakened lens array, while the speckles imposed on the spot by beamlets interference can be smoothed by spectral dispersion. Simulation results indicate that this scheme is a good candidate for improving the irradiation uniformity. The dependence of the smoothing performance on the characteristics of phase modulation and dispersion is further discussed, and it is found that parameters of the system of spectral dispersion and lens array must be chosen carefully to make optimal compromise between uniformity and usable energy of the laser beam.