bluuebunny/crossref_metadata_2025 huggingface dataset:
A method of color modulation based on porous alumina and atomic layer deposition
Authors: Wang Xu-Long-Qi  , Zhang Dong-Xian  , Zhang Hai-Jun  ,   State Key Laboratory of Modern Optical Instrumentation,Zhejiang University, Hangzhou 310027, China
Published: December 2020

By modeling and analyzing porous alumina (PA), a method to modulate the colors of PA templates is proposed, which is based on the preparation of PA templates and the atomic layer deposition (ALD) technique. Referring to the experimentally prepared PA samples, theoretical simulations are carried out for a series of PA templates with the same hole-diameter and hole-interval, but with different hole-depths. The relationship between the modulated colors and the hole-depths are thus disclosed. By controlling the time of anodization in oxalic acidsolution, two PA samples with different hole-depths (296 nm and 373 nm) were prepared, both with an average hole-diameter of 40 nm and an average hole-interval of 100 nm, respectively. ALD processing is then applied to deposit a layer of Fe2O3 film with total thickness of 16.8 nm on these samples. It was experimentally observed that the processed PA samples show different colors which change with hole-depths. The experimental results are in good agreement with the theoretical simulations, which proves the feasibility of color modulation with this method.
Threshold voltage model for quantum-well channelpMOSFET with poly SiGe gate
Authors: Qu Jiang-Tao  , Zhang He-Ming  , Wang Guan-Yu  , Wang Xiao-Yan  , Hu Hui-Yong  ,   Key Lab of Wide Band-Gap Semiconductor Materials and Devices, School of Microelectronics,Xidian University, Xi'an 710071, China
Published: December 2020

In this paper, threshold voltage model of quantum-well channel pMOSFET with p+polycrystalline SiGe gate and its cut-in voltage model were established based on solving Poisson equation while considering the impact of free carrier. The effects of relevant parameters (Ge concentration of poly SiGe gate, Ge concentration of quantum-well SiGe channel, thickness of oxide layer, thickness of Si cap layer, doping content of quantum-well SiGe channel, and doping content of substrate) on threshold voltage and cut-in voltage of the parasitic channel was analysed by numerical analysis, and obtained the methods to restrain the opening of parasitic channel. The results of the models are in good agreement wih that of experiment reported as well as of ISE simulation.
An investigation into the expression of potential vorticity in the common meteorological coordinate systems
Authors: Liu Shi-Jun  , Wang Xiu-Ming  , Tao Zu-Yu  , Zhou Xiao-Gang  ,   (1)China Meteorological Administration Training Center, Beijing 100081, China; (2)Physical School of Peking University, Beijing 100871, China
Published: December 2020

The potential vorticity theory and diagnostic techniques are based on the potential vorticity equation and expression in the common meteorological coordinate systems. In this paper, the potential vorticity equation and expression in the isobaric and isoentropic coordinates are gotten via coordinate transformation with the two methods. First, starting from the three-dimensional vector motion equation, the potential vorticity equations and expressions are gotten by the combination of the three-dimensional vorticity equation, continuity equation, and thermodynamic equation. Second, the potential vorticity equations and expressions are directly gotten from the corresponding scalar motion equations in the isobaric and isoentropic coordinates. The results show that potential vorticity expression is different with one method from that with the other in the isobaric coordinate system, and it is the same as each other in the isoentropic coordinate system. It was found, based on further analysis of the physical nature of the coordinates, that the isobaric and isoentropic coordinates are essentially treated as a mathematical coordinate system with the first method despite the coordinate transformation made for the term of pressure gradient force in the vector motion equation. From the procedure for the second method it is clearly seen that the isobaric and isoentropic coordinate systems are the physical coordinate system under the assumption of static equilibrium, which are not simply used as a mathematical coordinate system. As far as the isobaric coordinate is concerned, only the potential vorticity equation obtained from the scalar motion equations is the strict potential vorticity equation. As for the isoentropic coordinate, owing to the potential temperature gradient perpendicular to the isoentropic plane, the potential vorticity equation and expression are the same regardless of the coordinate being viewed as the physical or the mathematical.
Folded soliton with periodic vibration for a nonlinear coupled Schrödinger system
Authors: Li Bang-Qing  , Ma Yu-Lan  , Wang Cong  , Xu Mei-Ping  , Li Yang  ,   (1)School of Computer and Information Engineering, Beijing Technology and Business University, Beijing 100048, China; (2)School of Computer and Information Engineering, Beijing Technology and Business University, Beijing 100048, China; School of Mechanical Electronic and Information Engineering, China University of Mining and Technology, Beijing 100083, China; (3)School of Mechanical Electronic and Information Engineering, China University of Mining and Technology, Beijing 100083, China
Published: December 2020

Introducing symmetrical expansion and nonlinear transformation, the (G'/G)-expansion method is extended to investigate a nonlinear coupled Schrödinger system. Some exact solutions with variable separation are constructed for the system. The solutions involve two arbitrary functions of independent variables. By setting properly the arbitrary functions in the solutions, two types of folded solitons with periodic vibration are observed.
Influence of decoherence of entanglement on deterministic remote state preparation
Authors: Guo Zhen  , Yan Lian-Shan  , Pan Wei  , Luo Bin  , Xu Ming-Feng  ,   Center for Information Photonics and Communications, School of Information Science and Technology, Southwest Jiaotong University, Chengdu 610031, China
Published: December 2020

We investigate the influence of decoherence of entanglement on the deterministic remote state preparation. Firstly, the determinability and the depletion of entanglement bits and classical bits are obtained. Then two kinds of decoherent channels (depolarizing and dephasing) are analyzed. For the depolarizing channel, the fidelity is related only to the depolarization and the latitude of target quantum bits on the Bloch sphere, but is independent of longitude. For the dephasing channel, the fidelity is not affected by the quantum channel and only related to the latitude of target quantum bits.
Gap solitons of a superfluid fermion gas in optical lattices
Authors: Yang Shu-Rong  , Cai Hong-Qiang  , Qi Wei  , Xue Ju-Kui  ,   Key Laboratory of Atomic and Molecular Physics and Functional Materials of Gansu Province, College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070, China
Published: December 2020

Based on the hydrodynamic model, gap soliton of a superfluid fermion gas in optical lattices was discussed. By using the variational method, the condition for existing gap soliton is obtained. It is found that, when the system crosses from Bose-Eingtein condensation side to the BCS side, the condition for existing gap soliton and the structure of gap soliton are very different.
High-dimensional entanglement for long distance quantum communication
Authors: Yin Juan  , Qian Yong  , Li Xiao-Qiang  , Bao Xiao-Hui  , Peng Cheng-Zhi  , Yang Tao  , Pan Ge-Sheng  ,   Hefei National Laboratory for Physical Sciences at the Microscale, Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China
Published: December 2020

In this paper, we provide a scheme to generate a high-dimensional entanglement source for long distance quantum communication. We utilize a continuous wave pump laser to produce polarization-time two-body four-dimensional entangled photon pairs. Under 20 mW of pump power, we achieve 700 entangled photon pairs per second with a fidelity of 89%±3%. Compared with other known high dimension entangled sources, the developed source in the paper is easy to transmit over a long distance and its phase stability is easy to achieve. Therefore, the source is more suited for the future long distance high-dimensional quantum communication tasks and testing the quantum nonlocality, for example, long distance high dimensional quantum key distribution, experimental testing two-particle Greenberger-Horne-Zeilinger theorem, implementation of two-particle quantum pseudo telepathy, etc.
The thin film model without cutoff and the black hole entropy of Dirac field
Authors: Zhao Zheng  , Yang Xue-Jun  ,   (1)Department of Physics and Electronic Information, Shaoxing University, Shaoxing 312000, China; (2)Department of Physics, Beijing Normal University, Beijing 100875, China
Published: December 2020

The physical idea of thin film model improved from brick-wall model is more direct and clearer than brick-wall model and gives prominence to the significance of the event horizon serving as the characteristic surface of a static or stationary black hole. To remove the divergence of the density of states, an ultraviolet cutoff factor is also introduced into the thin film model. The cutoff is introduced artificially and it has not been understood clearly up to now. There is an indication in a reference that the divergence can be removed without any cutoff when the generalized uncertainty relation is used to calculate black hole entropy. In this paper, thin film model without cutoff and the essential difference between the thin film model without cutoff and the thin film model with cutoff are expounded by the example of calculating the entropy of spherically symmetric static black hole Dirac field.
Thermal rectification of asymmetric double-stranded molecular structure
Authors: Zhang Mao-Ping  , Zhong Wei-Rong  , Ai Bao-Quan  ,   (1)School of Plysics and Telecommunication Engineering, South China Normal University, Guangzhou 510006, China; (2)Siyuan Laboratory, Department of Physics, College of Science and Engineering, Jinan University, Guangzhou 510632, China
Published: December 2020

Using nonequilibrium molecular dynamics simulation, we study the thermal rectification of an asymmetric double-stranded molecular structure system. We investigate the influence of temperature, intra- and inter-chain interaction and the system size on the thermal rectification effect of the asymmetric double- chain system. It is reported that the intra- and the inter-chain interaction have an advantage on the rectification efficiency. The rectification efficiency goes to a stable value at a large system size. This phenomenon is also explained by the power spectra of the inter-particles, which is similar to the situation of the single chain system.
Microscopic expression of entransy
Authors: Cheng Xue-Tao  , Liang Xin-Gang  , Xu Xiang-Hua  ,   Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Engineering Mechanics, Tsinghua University, Beijing 100084, China
Published: December 2020

Boltzmann found that a proportional relation exists between the entropy and the logarithm of the microstate number in an approximate non-interaction particle system. The relation was expressed as the Boltzmanns entropic equation by Planck later. Boltzmanns work gives a microphysical interpretation of entropy. In this paper, a microscopic expression of entransy is introduced for an ideal gas system of monatomic molecules. The changes of the microstate number, the entropy and the entransy of the system are analyzed and discussed for an isolated ideal gas system of monatomic molecules going through the initial stage of unequilibriun thermal state to the thermal equilibrium state. It is found that the microstate number and the entropy always increase in the process, while the entransy decreases. The microstate number is a basic physical quantity which could measure the disorder degree of the system. The irreversibility of a thermal equilibrium process is attributed to the increase in microstate number. Entropy and entransy both are single value functions of the microstate number and they both could reflect the change of the state for the system. Therefore, both entropy and entransy could describe the irreversibility of thermal processes.
Effect of gaussian color-correlated colored noise on stochastic multiresonance of a bistable system
Authors: Zhang Xiao-Yan  , Xu Wei  , Zhou Bing-Chang  ,   Department of Applied Mathematics, Northwestern Polytechnical University, Xi’an 710072, China
Published: December 2020

We investigate the stochastic resonance of the bistable system driven by multiplicative and additive colored noises with colored cross-correlation. The expression of signal-to-noise ratio (SNR) is obtained by using the adiabatic limit. Through analyzing SNR with the initial condition of x(0)=x+ , we find the stochastic resonance and the stochastic multiresonance. We also find the effects of the noise intensity, the cross-correlation intensity and the correlation time of the noise on the SNR.
Monte Carlo simulations of the evolution of helium depth distribution in materials
Authors: Zhou Yu-Lu  , Li Ren-Shun  , Zhang Bao-Ling  , Deng Ai-Hong  , Hou Qing  ,   (1)Department of Applied Physics, Sichuan University, Chengdu 610064, China; (2)Key Laboratory for Radiation Physics and Technology of Ministry of Education, Institute of Nuclear Science and Technology, Sichuan University, Chengdu 610064, China; (3)Key Laboratory for Radiation Physics and Technology of Ministry of Education, Institute of Nuclear Science and Technology, Sichuan University, Chengdu 610064, China; Department of Applied Physics, Sichuan University, Chengdu 610064, China
Published: December 2020

Based on the migration-coalescence mechanism for helium bubble growth in a material, the evolution of helium depth distribution during annealing is simulated by the Monte Carlo method. The factors that influence the evolution are studied. The results show that the initial concentration and radius of the helium bubble can affect the evolution of He depth distribution, while the annealing temperature has influence only on the evolution rate but little on the final depth distribution of helium. It is also shown that the evolution of the system turns to slow down gradually with the annealing time going.
Wind retrieval algorithm of Rayleigh Doppler lidar
Authors: Shu Zhi-Feng  , Dou Xian-Kang  , Wang Zhong-Chun  , Shen Fa-Hua  , Sun Dong-Song  , Xue Xiang-Hui  , Chen Ting-Di  ,   (1)Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China; (2)Department of Physics, Yancheng Teachers University, Yancheng 224002, China; (3)School of Space and Earth Science, University of Science and Technology of China, Hefei 230026, China
Published: December 2020

The wind measurement principle and the structure of Rayleigh Doppler lidar are introduced. The method for Fabry-Perot(FP) etalon transmission curve calibration is given. The problem is pointed out that to fit the transmission curve by using Lorentz or Voigt function may induce large error: the relative error would be up to 8% by Lorentz fitting especially. A least-square nonlinear fitting procedure is proposed, which can eliminate the fitting error and improve the wind precision. After the dominant role that the temperature uncertainty plays in wind retrieval process is considered, a nonlinear iterative algorithm is proposed, which can retrieve both wind temperature and atmospheric temperature. Simulation results show that the algorithm proposed can improve wind retrieval accuracy effectively compared with the traditional method without the Mie-induced effect, and the wind retrieval accuracy of the algorithm proposed will be degraded with Mie-induced effect but still better than that of traditional method.
Spectroscopic parameters and molecular constants of CSe(X1Σ+) radical
Authors: Sun Jin-Feng  , Zhu Zun  , Liu Hui  , Shi De-Heng  ,   (1)College of Physics and Electronic Engineering, Xinyang Normal University, Xinyang 464000, China; (2)College of Physics and Information Engineering, Henan Normal University, Xinxiang 453007, China
Published: December 2020

The spectroscopic and molecular properties of CSe(X1Σ+) radical are investigated using the complete active space self-consistent field (CASSCF) method followed by the highly accurate valence internally contracted multireference configuration interaction (MRCI) approach. The potential energy curve (PEC) is calculated over the internuclear separation range from 0.08 to 2.5 nm at the basis sets, aug-cc-pV5Z for C and aug-cc-pV5Z-pp for Se atom. The spectroscopic parameters (D0, De, Re, ωe, ωexe, αe and Be) of six isotope molecules (12C74Se, 12C76Se, 12C77Se, 12C78Se, 12C80Se and 12C82Se) are evaluated using the PEC of CSe(X1Σ+) radical. The spectroscopic parameters are compared with those reported in the literature, and excellent agreement is found between them. With the PEC of CSe(X1Σ+) radical obtained here, a total of 81 vibrational states of 12C80Se species are predicted when J = 0 by numerically solving the radical Schrödinger equation of nuclear notion. For each vibrational state of every isotope species, the vibrational levels, classical turning points and inertial rotation constants are reported, which are in agreement with the available experimental data.
Structure and potential energy functionof XF2(X=B,N) molecular ground state
Authors: Xiao Xia-Jie  , Han Xiao-Qin  , Liu Yu-Fang  ,   (1)Collegel of Physics and Information Engineering, Henan Normal University, Xinxiang 453007 China; (2)Collegel of Physics and Information Engineering, Henan Normal University, Xinxiang 453007 China; Henan Quality Polytechnics, Pingdingshan 467000 China; (3)Department of Physics and Information Engineering, Shangqiu Normal College, Shangqiu 476000 China
Published: December 2020

Based on the Gaussian03 calculation software, QCISD method is used to optimize the possible ground-state structures of XF2(X=B,N) molecules with the different basis sets. On this basis, the resonant frequencies and force constants are calculated with the D95(df, pd) and D95+(df, pd) basis sets respectively. The potential energy functions of XF2(X=B,N) are derived from the many-body expansion theory. At the same time, according to the potential energy functions, three equivalent potential energy diagrams for the XF2(X=B,N) ground states are drawn. The potential energy surface is verified to be consistent with the three atomic molecular geometry. The structures and the features of XF2(X=B,N) can correctly reappear on the potential surface.
Influence of Sommerfeld parameters on triple differential cross section in non-coplanar geometry
Authors: Chen Zhan-Bin  , Yang Huan  , Wu Xing-Ju  , Zhang Sui-Meng  ,   (1)College of Physics and Electrical Information, Anhui Normal University, Wuhu 241000, China; (2)College of Physics and Electrical Information, Anhui Normal University, Wuhu 241000, China; Institute of Atomic and Molecular Physics, Department of Mathematics and Physics, West Anhui University, Lu’an 237012, China; (3)Institute of Atomic and Molecular Physics, Department of Mathematics and Physics, West Anhui University, Lu’an 237012, China
Published: December 2020

The effective shield of residual electron in the final state of He+ is further modified for (e, 2e) processes on Helium. Three different amendments to the program are proposed in non-coplanar geometry. The effects of the Sommerfeld parameters on the triple differential cross section and the physical nature of these effects are considered.
Fast linear transformer high power pulse generator
Authors: Xiang Fei  , Tan Jie  , Luo Min  , Wang Gan-Ping  , Kang Qiang  ,   Institute of Applied Electronics, China Academy Engineering of Physics, Mianyang 621900, China
Published: December 2020

The realization technique of fast linear transformer driver on the compact modularized high power pulse generator was expounded. The influence on Modular amount and the output quality of fast linear transformer driver (FLTD) was analyzed. The limitation on FLTD primary inductance was reduced by optioned feeding structure. The waveform distortion was weakened by designed back swing coil. Through engineering experiments, electron beam closed 0.8MeV with repetition frequency of 25 Hz and top time of ~80 ns were obtained. So this paper gave a new idea for research on the modularization compact high power pulse generator with higher repetition rate.
Sensitivity analysis of hybrid fiber Fabry-Pérot refractive-index sensor
Authors: Gong Yuan  , Guo Yu  , Rao Yun-Jiang  , Zhao Tian  , Wu Yu  , Ran Zeng-Ling  ,   Key Laboratory of Optical Fiber Sensing and Communications of Ministry of Education, University of Electronic Science and Technology of China, Chengdu 611731, China
Published: December 2020

Theoretical expressions for analyzing the refractive-index sensitivity of the hybrid optical fiber Fabry-Pérot sensor is developed. Influence of the experimental parameters on the measurement sensitivity is discussed. Hybrid optical fiber Fabry-Pérot sensor is fabricated by chemically etching a graded-index multimode fiber (GI-MMF), fusion splicing it into a single mode fiber, and cleaving the GI-MMF. The fringe contrast exceeds 30 dB and the corresponding measurement sensitivity of refractive index is about 45 dB per refraction index unit. Experimental results are in good agreement with the theoretical ones. It is indicated by the numerical simulations that the performance of this kind of sensor can be further improved.
Generation of 27 GHz flat broadband chaotic laser with semiconductor laser loop
Authors: Feng Ye  , Yang Yi-Biao  , Wang An-Bang  , Wang Yun-Cai  ,   Department of Physics and Optoelectronics, Taiyuan University of Technology, Taiyuan 030024, China
Published: December 2020

Generation of flat broadband chaotic signal is demonstrated experimentally with a semiconductor laser loop, which consists of three laser diodes mainly. The output of each laser diode is injected into its neighbor diode as a loop. The injection light strength is controlled with erbium-dropped optical fiber amplifier or attenuator which is inserted between the diodes, and the detuning is adjusted by changing the temperature of the laser diode. Limited by the bandwidth of the laser diode, the bandwidth of the flat broadband chaotic signal is broader than 27 GHz or even more, and the fluctuation of the spectrum cure is less than 5 dB.
Influence of turbulence on the Rayleigh range of partially coherent cosh-Gaussian beams
Authors: Ji Xiao-Ling  ,   Department of Physics, Sichuan Normal University, Chengdu 610066, China
Published: December 2020

The analytical expressions for the Rayleigh range of partially coherent cosh-Gaussian beams both in free space and in atmospheric turbulence are derived. The influence of turbulence on the Rayleigh range of partially coherent cosh-Gaussian beams is studied. It is shown that the Rayleigh range of partially coherent cosh-Gaussian beams depends on the strength of turbulence and the beam parameters. The Rayleigh range decreases due to turbulence. The stronger the turbulence, the shorter the Rayleigh range is. In free space, the Rayleigh range increases with the increase of beam coherence parameter α , beam parameter β and Gaussian waist width w 0, and the decrease of wave length λ. However, the Rayleigh range is less sensitive to turbulence with α , β and w 0 decreasing and λ increasing. Furthermore, the influence of turbulence can be ignored when α , β and w 0 are small enough and λ is large enough.
Mode locked multi-core photonic crystal fiber laser
Authors: Fang Xiao-Hui  , Hu Ming-Lie  , Song You-Jian  , Xie Chen  , Chai Lu  , Wang Qing-Yue  ,   Key Laboratory of Opto-electronic Information Science and Technology of Ministry of Education, College of Precision Instruments and Opto-electronics Engineering , Tianjin University, Tianjin 300072, China
Published: December 2020

A mode locked fiber laser based on Yb-doped large mode area photonic crystal fiber operating in the all-normal dispersion regime is experimentally studied. The eighteen cores of the gain fiber are arranged in array-type geometry with an equivalent mode diameter of about 52 μm. A sigma laser cavity is used without using any elements for dispersion compensation. Reliable self-starting mode-locking is achieved using a fast semiconductor saturable absorber mirror. The laser directly produces 4.92 ps chirped pulses at a 44.68 MHz repetition rate for an average power of 3.3 W corresponding to a pulse energy of 74 nJ. The pulses are compressed to 780 fs with a grating pair outside the cavity.
Effect of light polarization on thermal light correlated imaging
Authors: Zhang Er-Feng  , Dai Hong-Yi  ,   Department of Physics, College of Science, National University of Defense Technology, Changsha 410073, China
Published: December 2020

Based on the effect of the polarization state of polarized light and the degree of polarization on the second-order correlation function, the influence of light polarization on visibility and signal-to-noise ratio (SNR) is investigated by use of the statistical optics theory. It is shown that only the polarization degree has effect on thermal light correlated imaging. The visibility of correlated imaging is a quadratic function of the polarization degree. An increase in the polarization degree leads to an increase in the SNR of conventional correlated imaging, but the SNR obtained by substracting the background and using the second-order coherent degree is independent of polarization degree.
Solitons of nonlinear Schrödinger equation withvariable-coefficients and interaction
Authors: Qian Cun  , Wang Liang-Liang  , Zhang Jie-Fang  ,   Institute of Nonlinear Physics, Zhejiang Normal University, Jinhua 321004, China
Published: December 2020

Search for exact solutions to the generalized nonlinear Schrödinger equation is one of the essential directions in studies of the nonlinear dynamics in optical soliton and Bose-Einstein condensates. Stable soliton modes are of great significance for the experimental realization and potential application. In this paper, based on the introduction of a similarity transformation, the variable-coefficient nonlinear Schrödinger equation is transformed into the nonlinear Schrödinger equation, and then the single soliton solution, two-soliton solution and soliton solution in continuous-wave background for the variable coefficient nonlinear Schrödinger equation are obtained by using the known solutions. Meanwhile, their image analysis and relative discussion are given by selecting the different parameters in detail.
Equal intensity polarization-independent beam splitter based on photonic crystal self-collimation ring resonator
Authors: Tong Xing  , Han Kui  , Shen Xiao-Peng  , Wu Qiong-Hua  , Zhou Fei  , Ge Yang  , Hu Xiao-Juan  ,   College of Science, China University of Mining and Technology, Xuzhou 221116, China
Published: December 2020

By the equi-frequency contour analysis and the finite-difference time-domain simulation, it is observed that the distance of one lop in a photonic crystal self-collimation ring resonator can cause different periodic outputs of the ring resonator for TE and TM polarizations. Equal intensity polarization-independent beam splitter can be achieved by choosing a suitable propagation distance. It expands the range of application of beam splitter and will play a great role in integrated optical circuits.
Surface capillary wave and the eighth mode sectorial oscillation of acoustically levitated drop
Authors: Yan Zhen-Lin  , Xie Wen-Jun  , Shen Chang-Le  , Wei Bing-Bo  ,   Department of Applied Physics, Northwestern Polytechnical University, Xi’ an 710072, China
Published: December 2020

The suspension of liquid drops provides a preferable boundary condition for investigating various free surface phenomena. Here we report the observation of concentric capillary wave formed on the surface of drastically flattened water drops levitated in ultrasound. The measured wavelength of capillary wave accords well with that from the classic dispersion relation equation. The eighth mode sectorial oscillation of acoustically levitated drop is excited by the active modulation of sound pressure. It is found that these phenomena are due to parametric excitation. The capillary wave is induced when the parametric instability arises and ultrasound pressure exceeds a threshold pressure. The sectorial oscillations take place when the equatorial radius varies at twice the natural sectorial frequency of the levitated drop. The frequency of the eighth mode sectorial oscillation decreases with the increase of equatorial radius and can be well described by modifying the Rayleigh equation. Further analysis reveals the parametric excitation mechanism for this kind of oscillations.
Discrete variational calculation of Hénon-Heiles equation in the Birkhoffian sense
Authors: Liu Chang  , Guo Yong-Xin  , Liu Shi-Xing  ,   (1)College of Physics, Liaoning University, Shenyang 110036, China; (2)Department of Applied Mechanics, Beijing Institute of Technology, Beijing 100081, China; (3)Department of Applied Mechanics, Beijing Institute of Technology, Beijing 100081, China; College of Physics, Liaoning University, Shenyang 110036, China
Published: December 2020

The Hénon-Heiles equation that is nonlinear nonintegrable Hamilton system is studied by using the method of discrete variational valculation in the Birkhoffian sense. And the result from the method is compared with the result obtained by using symplectic algorithm and Runge-Kutta method, indicating that the method presented in this paper is reasonable and feasible in computing the dynamical action of the nonlinear nonintegrable Hamilton system in the Birkhoffian sense.
Characteristics and structure of magnetotail flux rope recovered from Grad-Shafranov method
Authors: Zhang Yong-Cun  , Shen Chao  , Liu Zhen-Xing  ,   State Key Laboratory of Space Weather, Center for Space Science and Applied Research, Chinese Academy of Sciences, Beijing 100190, China
Published: December 2020

On 21 February 2009, THEMIS-C satellite observed the classical signal of magnetic flux rope at magnetotail of X=-15.7RE.We take the method of Grad-Shafranov reconstruction to investigate the characteristics and structure of magnetotail flux rope. The results give the characteristic physics parameters such as the invariant axis direction, the cross scale length, the magnetic flux in flux rope, etc. With no constraint from model on shape of the flux rope, we reconstruct the distribution of magnetic field and electric current density in the cross section of magnetic flux rope at magnetotail. Our results show that the magnetic field in the central region of magnetic flux rope can be described as being force-free, while with the increase of radial distance, the fields display no force-free feature in the region where the magnetic fields deviate from the axial symmetric distribution.
Comparison of damage between front and rear surfaces under nanosecond 355nm laser irradiation on fused silica
Authors: Liu Hong-Jie  , Zhou Xin-Da  , Huang Jin  , Wang Feng-Rui  , Jiang Xiao-Dong  , Huang Jing  , Wu Wei-Dong  , Zheng Wan-Guo  ,   Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

To investigate the physical mechanism which causes asymmetric damages in front and rear surfaces, time-resolved dynamics of the fused silica’s surface damage induced by the nanosecond ultraviolet laser is studied using shadow graphic technique. The results show that the damage mechanisms in front and rear surfaces under nanosecond laser interaction with fused silica are absolutely different. Although the plasma and the shock waves in air are relatively high, damage is reduced on the front surface because the plasma shielding limits energy deposition of the remnant pulse .While on the rear surface, two factors aggravate the damage, one comes from the impulsion of the plasma after its absorption of the laser energy, the other comes from the interference between the remnant pulse and the reflected pulse from the plasma. It is instructive to understand the damage mechanism.
Features of electron-wall collision frequency with saturated sheath in Hall thruster
Authors: Zhang Feng-Kui  , Ding Yong-Jie  ,   (1)College of Aerospace and Civil Engineering, Harbin Engineering University, Harbin 150001, China; (2)School of Energy Science and Engineering, Harbin Institute of Technology, Harbin 150001, China
Published: December 2020

In the paper we study the electron-wall collision frequency in Hall thruster using the two-dimensional particle-in-cell method. It is found that electron-wall collision frequency is greatly increased in the state of saturated sheath compared with in the state of classic sheath, and even two orders of magnitude higher. Thus, the contribution of electron-wall collision frequency in the state of saturated sheath to near-wall current will be non-ignorable. In this paper the reason why the electron-wall collision frequency is increased in the state of saturated sheath is further analysed. It is believed that the increase of electron-wall collision frequency is caused by rather low sheath potential drop and the backflow of secondary electron emitted from the wall.
Defects in transition between different filament structures in dielectric barrier discharge
Authors: Dong Li-Fang  , Li Shu-Feng  , Fan Wei-Li  ,   College of Physics Science and Technology, Hebei University, Baoding 071002, China
Published: December 2020

The defects in the transition from square to square grid states are studied in a dielectric barrier discharge. It is found that there exist two kinds of defects in this transition, which are angle defect and dislocation defect. In order to investigate the formation mechanism of the defects, the light emissions from different filaments are measured, which show that the light intensity of filament in the middle of the octagonal cell is larger than that in the side. By introducing the quasi-potential field, the interactions between filaments as well as their influences on the transition between different structures are studied. From above analyses, the defects that could emerge in the transition are suggested, which are in good agreement with that observed in experiments.
Nanowelding of contact between carbon nanotubesand gold electrodes
Authors: Zuo Xue-Yun  , Li Zhong-Qiu  , Wang Wei  , Meng Li-Jun  , Zhang Kai-Wang  , Zhong Jian-Xin  ,   Faculty of Materials, Optoelectronics and Physics, Xiangtan University, Xiangtan 411105, China
Published: December 2020

We report on the results of molecular dynamics simulations of nanowelding at high temperature between the gold electrodes and single-walled carbon nanotubes (SWNTs). We find that SWNTs with gold nanoclusters absorbed on their tips can build an excellent welding contact with gold electrodes. First, gold clusters are placed on open tips of SWNTs and are annealed at 1100 K. Gold atoms enter into the SWNTs and a shell-like helical structure inside the SWNTs and an amorphous structure outside of the SWNTs. Furthermore, the SWNTs absorbed with gold cluster are then placed on surfaces of gold electrodes. After annealing at high temperature, gold atoms absorbed in the SWNTs are redistributed on the surface of the gold electrodes and form excellent welding contact with the electrodes. The best annealing temperature for welding is about 800 K.
Analysis of heterogeneous nucleation on rough surfacesbased on Wenzel model
Authors: Zheng Hao-Yong  , Wang Meng  , Wang Xiu-Xing  , Huang Wei-Dong  ,   State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xian 710072, China
Published: December 2020

Heterogeneous nucleation plays an important part in the solidification process. In order to describe the effects of the substrate surface on the heterogeneous nucleation, an idealized planar interface between the nucleus and the substrate is assumed in the consideration of the classical nucleation theory, but this may lead to the deviation of the experimental results from the theoretical predictions, since there is no idealized planar surface on any actual substrate. The heterogeneous nucleation procedure of solid phase on rough substrate surface is investigated, and the effect of the roughness factor of the substrate on nucleation energy is analyzed based on the Wenzel wetting model. The results show that when the intrinsic contact angle between the substrate and the nucleus in the base phase is less than 90°, higher roughness of the substrate surface makes it easier to induce heterogeneous nucleation; when intrinsic contact angle is greater than 90°, higher roughness would restrict the nucleation on the substrate surface. Meanwhile, attaching and wetting drift embryos on the substrate play an important part in the formation of effective nucleus on the substrate, while the change of interfacial free energy in the wetting process of the embryos on the rough substrate surface has an important effect on heterogeneous nucleation behaviors.
Molecular dynamics simulation of thermal conductivity for the TiO2/ZnO nano-film interface
Authors: Yang Ping  , Wu Yong-Sheng  , Xu Hai-Feng  , Xu Xian-Xin  , Zhang Li-Qiang  , Li Pei  ,   School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013, China
Published: December 2020

In the paper, the equilibrium molecular dynamics and Buckingham potential function are used to investigate the thermal conductivity of TiO2/ZnO nano-film interface along to [0001](z-axis). The effects of the equilibrium temperature, the thickness and the cross section of the nano-film interface on the thermal conductivity of TiO2/ZnO are investigated by optimizing the cut-off radius(rc)and the time step for initial condition of molecular dynamics. The results indicate that the thermal conductivity of TiO2/ZnO nano-film interface decreases with temperature increasing from 300 K to 600 K, and increases with film thickness increasing from 1.8 to 5 nm. Finally, the relationship between the thermal conductivity and the thickness of TiO2/ZnO nano-film interface is discussed.
Electronic structures cobalt group pnictides: BaT2P2 and BaT2As2 (T=Co, Rh, Ir)
Authors: Qian Yu-Min  , Xu Gang  ,   Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
Published: December 2020

We study the electronic structure of cobalt pnictides: BaT2P2 and BaT2As2 (T=Co, Rh, Ir) by the density functional theory within generalized gradient approximation, and find that the ferromagnetisms in BaCo2As2 and BaCo2P2 are due mostly to the high density of states (Van-Hove singularity) at Fermi level, which induce Stoner ferromagnetism. In these compounds, from Co-3d to Rh-4d, then to Ir-5d, the d-d bonding and the d-p bonding in the TX4(X=P, As) layers are strengthened. As a result, the antibonding d-d states are pushed away from the Fermi level, and the ferromagnetisms are suppressed in Rh and Ir compounds. The evolutions and the detailed electronic structures of these compounds are studied and compared, and spin orbital coupling interaction is negligible.
Theoretical study on electronic structure and properties of solid carbon dioxide
Authors: Qu Nian-Rui  , Gao Fa-Ming  ,   Department of Applied Chemistry, Yanshan University, Qinhuangdao 066004, China
Published: December 2020

We systematically investigate the equilibrium energy, the density of states, and the elastic property of solid CO2 by the plane wave pseudo-potential method in the generalized gradient approximation and local density approximation based on the density function theory. The calculated lattice parameters of α-quartz are consistent with other calculation values. The equilibrium energy calculation indicates that β-cristobalite structure is more stable under the ambient condition, which is consistent with the results reported in other reffrences.The computation results of elastic constants show that they are elastically stable in structure exception for stishovite and cubic-pyrite. The hardness values for these structures are evaluated according to the intrinsic hardness calculation theory of covalent crystal based on the Mulliken overlap population. The results indicate that none of these phases are of superhard material. Furthermore, we clarify the stereochemical effect of the lone-pair electrons on the hardness of the solid CO2.
Preparation and thermoelectric properties of β-Zn4Sb3/Zn1-δAlδO
Authors: Zhou Li-Mei  , Li Wei  , Jiang Jun  , Chen Jian-Min  , Li Yong  , Xu Gao-Jie  ,   Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China
Published: December 2020

Single-phased β-Zn4Sb3 and β-Zn4Sb3/ Zn1-δAlδO composites with different amounts of Zn1-δAlδO (AZO) are prepared by the combination of vacuum melting and spark plasma sintering (SPS). Thermoelectric properties of the materials are investigated in a temperature range from 300 K to 673 K. As a result, the electrical conductivity of each sample increases while the Seebeck coefficient and the thermal conductivity decrease with the increase of AZO. The maximum ZT value of the composite reaches 1.16 at 673 K when the amount of AZO is 0.2 wt%, which is higher than that for the single-phased β-Zn4Sb3 (1.03).
Aging in the electrical properties of nanostructured vanadium oxide thin film exposed to air
Authors: Luo Zhen-Fei  , Wu Zhi-Ming  , Xu Xiang-Dong  , Wang Tao  , Jiang Ya-Dong  ,   State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China, Chengdu 610054, China
Published: December 2020

Radio frequency magnetron sputtering method is used to grow nanostructured VOx thin film on silicon nitride layer. X-ray diffraction and atomic force microscope are used to characterize the crystal structure and surface morphology, respectively. The variations of square resistance and thermal hysteresis loop are studied when the film is exposed to air for a long period of time, and the effects of these variations on the performance of device are analyzed. X-ray photoelectron spectrometer and Fourier transform infrared spectroscopy are employed to investigate the differences in composition and molecular structure between the fresh and aged films. The results indicate that the increase of square resistance is due to the oxidation of vanadium ions with low oxidation states. The reason to cause the change of thermal hysteresis loop is that the molecular structure of nanostructured VOx thin film is affected by the adsorbed atoms and functional groups.
Effects of cross-section shape on fast electron beams excited plasmons in the surface of nanowire pairs
Authors: Wang Lei  , Cai Wei  , Tan Xin-Hui  , Xiang Yin-Xiao  , Zhang Xin-Zheng  , Xu Jing-Jun  ,   Key Laboratory of Weak-Light Nonlinear Photonics of Ministry of Education, School of Physics, Nankai University, Tianjin 300071, China; Teda Applied Physics School, Nankai University, Tianjin 300457, China
Published: December 2020

In this paper,we investigate the gap plasmon excitation by swift electron beams in nanowire pairs, in particular, with different cross-section shapes (including circular, wedge and irregular shape). For all these nanowire pairs, our results show that fast electron beams can efficiently excite low-order monopole-monopole gap plasmons, which possess long propagation distance and well spatial localization. Furthermore, in contrast to high-order plasmons, the excited gap plasmons do not depend highly on cross-section shape of nanowire pairs through comparing the merit parameters in these three kinds of waveguides. Besides, the excited gap mode will be more confined in nanowire pairs with wedge cross-section. Our study will be helpful for the experiments of gap plasmon generation using electron microscope.
Effects of thickness for Al doped ZnO thin films on their microstructure and magnetic properties
Authors: Gu Jian-Jun  , Zhang Hai-Feng  , Xu Qin  , Liu Li-Hu  , Sun Hui-Yuan  , Qi Yun-Kai  ,   College of Physics Science and Information Engineering, Hebei Normal University, Shijiazhuang 050016, China; Key Laboratory of Advanced Films of Hebei Province, Shijiazhuang 050016, China;,   College of Physics Science and Information Engineering, Hebei Normal University, Shijiazhuang 050016, China; Key Laboratory of Advanced Films of Hebei Province, Shijiazhuang 050016, China; Department of Physics, Hebei Normal University for Nationalities,;,   Key Laboratory of Advanced Films of Hebei Province, Shijiazhuang 050016, China
Published: December 2020

Al doped ZnO films of different thickness have been prepared on glass substrates by dc magnetron sputtering, these films were annealed in different atmosphere . The crystal structures were analyzed by x-ray diffraction (XRD), and the magnetic properties were measured by a Physical Properties Measurement System (PPMS) with the magnetic field paralleled to the films plane. The results indicate that with increase of the thickness, the crystallinity of the thin films gets better and the crystallites of the Al doped ZnO thin films increase gradually, whereas the internal stresses decreased. The results show the films annealed in air shows obvious room temperature ferromagnetism. With the increase of the film thickness the saturation magnetization is enhanced, and the coercivity is weakened.
Effect of compressive stress on the magnetization and magnetostriction of Fe0.81 Ga0.19 alloy
Authors: Zhang Hui  , Zeng De-Chang  , Liu Zhong-Wu  ,   School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, China
Published: December 2020

The magnetomechanical effect and the magnetostriction in the -oriented single crystal of Fe0.81Ga0.19 alloy have been investigated on the basis of Stoner-Wohlfarth model. The results have shown that in the demagnetized state the degeneracy of the resultant anisotropy in the alloy from the original cubic magnetocrystalline anisotropy into the biaxial anisotropy occurs under a critical stress. This leads to an increase in the fractional occupancy of 90° domain which causes an increase the bulk magnetostriction.
Electronic structure and photoluminescence properties of Ca2GeO4 ∶Eu3+ in ultraviolet and vacuum ultraviolet region
Authors: Qin Qing-Song  , Yu Ming-Hui  , Zhou Hong-Liang  , Zhou Mei-Jiao  , Xiang Xiao-Tian  , Li Xiao-Di  , Zeng Jun-Xi  , Zhang Jia-Chi  ,   Key Laboratory for Magnetism and Magnetic Materials of Ministry of Education, Lanzhou University, Lanzhou 730000, China
Published: December 2020

Red emitting Ca2GeO4 ∶Eu3+ phosphors are synthesized by solid state method. The ultraviolet and vacuum ultraviolet excited photoluminescence properties are investigated in detail. The phenomenon of reduction of Eu3+ ions in air and the color switches are discovered and explained. The Ca2GeO4 ∶Eu3+ presents intense excitation intensities at 163—230, 301 and 466 nm, showing the potential applications in plasma display panels and light emitting diodes. The excitation spectra are studied to identify the photoluminescence mechanism of Ca2GeO4 ∶Eu3+ . First principles calculation within the local density approximation of the density functional theory is used to calculate the electronic structure and the linear optical properties of Ca2GeO4.