bluuebunny/crossref_metadata_2025 huggingface dataset:
Electrostatic potential distribution of high-order weakly nonlinear composites under external direct current electric field
Authors: Zhao Qing-Kai  , Chen Xiao-Gang  , Cui Ji-Feng  ,   College of Science, Inner Mongolia University of Technology, Hohhot 010051, China;,   School of Naval Architecture, Ocean and Civil Engineering, Shanghai Jiaotong University, Shanghai 200240, China
Published: December 2020

By using the homotopy analysis method (HAM), the electrostatic potential distribution problems of a type of high-order weakly nonlinear composite with a cylindrical inclusion randomly embedded in a host medium, which obeyes a current-field constitutive relation of J = σ E + χ |E|2E + η|E|4E, are investigated under the action of an external direct current electric field. With the mode expansion method, the current-field constitutive relation and their boundary conditions are transformed into a series of boundary value problems of nonlinear ordinary differential equations. Then the HAM is used to solve the boundary value problems of nonlinear ordinary differential equations and the asymptotic analytical solutions of electrostatic potential distribution in the inclusion and the host regions are given.
First-principles calculations of the electronic transport in Au-Si-Au junctions
Authors: Liu Fu-Ti  , Cheng Yan  , Yang Fu-Bin  , Cheng Xiao-Hong  , Chen Xiang-Rong  ,   College of Physical Science and Technology, Sichuan University, Chengdu 610064, China;,   College of Physics and Electronic Engineering, Yibin University, Yibin 644000, China
Published: December 2020

The transport property of silicon sandwiched between Au (100) and Au (100) is investigated with a combination of density functional theory and non-equilibrium Green's function method. It is found that the conductance decreases with distance increasing. When dz =9.72 Å, the structure of junctions is the most stable and the conductance is 1.227G0 (G0=2e2/h) , which is contributed by the px, py and pz electron orbits of silicon atom. The I-V curve of junctions in stable station show linear characteristics under external bias vottage. With the increase of an external positive and negative voltage, the conductance decreases slightly, and the asymmetry change appears.
First-principles study on the elastic, electronic and thermodynamic properties of ErNi2B2C under high pressure
Authors: Yan Xiao-Zhen  , Kuang Xiao-Yu  , Mao Ai-Jie  , Kuang Fang-Guang  , Wang Zhen-Hua  , Sheng Xiao-Wei  ,   Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, China
Published: December 2020

The elastic, electronic and thermodynamic properties of the superconducting ErNi2B2C material at high pressure are investigated using the plane-wave pseudopotential density functional theory. The analysis shows the dependences of the elastic constants, bulk modulus, shear modulus, Young's modulus and elastic anisotropy factors on the applied pressure. The calculated electronic density of states (DOS) reveals that the DOS peak at the Fermi level (EF) will decrease noticeably with pressure. It can be concluded that the pressure may reduce the superconducting temperature (Tc) of ErNi2B2C since the relatively high Tc originates from the peak in the DOS. This phenomenon is also found in some other superconductors such as MgB2 and SrAlSi. Moreover, based on the quasi-harmonic Debye model, the results of the thermodynamic properties indicate that the pressure and temperature have significant influences on the thermal expansion coefficient and heat capacity.
Study on interface of Al/depleted uranium and Au/depleted uranium layers deposited by magnetron sputtering
Authors: Yi Tai-Min  , Xing Pi-Feng  , Zheng Feng-Cheng  , Mei Lu-Sheng  , Yang Meng-Sheng  , Zhao Li-Ping  , Li Chao-Yang  , Xie Jun  , Du Kai  , Ma Kun-Quan  ,   Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

Aluminum/depleted uranium/aluminum (Al/DU/Al) and gold/depleted uranium/gold (Au/DU/Au) "sandwich structure" films are deposited by magnetron sputtering. Diffusions of Al/DU and Au/DU interface of these samples are investigated by high resolution scanning electronic microscope, X-ray diffraction, X-ray photoelectron spectrometer and scanning auger microprobe. The results show that deposited DU layer is of columnar grain. Significant diffusion takes place at Al/DU interface. Intermetallic compounds of Al2U and Al3U are formed at Al/DU interface by chemical reaction between Al and DU which induces chemical shift toward high binding energy of Al 2p and toward low binding energy of U 4f. Microdosages of O exist in Al over-layers as Al2O3, in Al/DU interface as Al2O3 and oxidation of uranium, and in DU layers as oxidation of uranium respectively. Just simple physical diffusion takes place at Au/DU interface. Binding energies of Au 4f and U 4f shift toward high-energy tail induced by cluster effect at the Au/DU interface. Microdosages of O exist at Au/DU interface and in DU layers as oxidation of uranium. Diffusion at the Al/DU interface is more obvious than at Au/DU surface. Under the condition of the same thickness valuses Al over-layer is more effective than Au over layer to protect uranium layer from oxidging.
Preparation, formation mechanism and optical properties of C/Cu shell/core nanostructures
Authors: Huang Xiao-Lin  , Hou Li-Zhen  , Yu Bo-Wen  , Chen Guo-Liang  , Wang Shi-Liang  , Ma Liang  , Liu Xin-Li  , He Yue-Hui  ,   School of Physics and Electron, Central South University, Changsha 410083, China;,   Institute of Physics and Information Science, Hunan Normal University, Changsha 410081, China;,   State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China
Published: December 2020

Copper/carbon core/shell structure nanoparticles and nanowires are successfully synthesized by using a one-step low-temperature metal-organic chemical vapor with copper (II) acetylacetonate powders as precursor. Morphology and structure of copper/carbon core/shell nanomaterial can be well controlled by deposition temperature For instance, copper/carbon core/shell nanowires about 200 nm in diameter can be produced at 400 ℃. The mixture of nanowires and nanoparticles can be produced at 450 ℃. At 600 ℃ the production is the copper/carbon core/shell nanoparticles about 22 nm in diameter. The obtained copper/carbon core/shell nanostucture is found to be formed by a novel coalescence mechanism that is quite different from the well-known dissolution-precipitation mechanism The optical property of copper/carbon core/shell nanostructure is investigated Uv-vis spectrometer and the fluorescence spectrometer (PL). The results show that the surface plasma resonance peaks of copper/carbon core/shell nanowire and nanoparticle are located at 620 nm and 616 nm respectively. At 225 nm, copper absorbing peak can be found. The PL peaks of copper/carbon core/shell nanowires are located at 312 nm and 348 nm, and the PL peaks of copper/carbon core/shell nanoparticles are observed at 304 nm and 345 nm.
A three-dimensional surface evolution algorithm based on cellular model for etching process
Authors: Zheng Shu-Lin  , Song Yi-Xu  , Sun Xiao-Min  ,   Department of Computer Science and Technology, Tsinghua University, State Key Laboratory of Intelligent Technology and Systems, Beijing 100084, China
Published: December 2020

In order to get a better understanding of etching mechanism and provide optimization guidance for manufacturing process, a three-dimensional (3D) profile evolution simulator based on cellular model is developed to investigate the surface evolution of etching process, and discuss emphatically the effect of ions on the surface evolution. According to the solving problem for angle of ion incidence, a component fitting-based dimension reduction method is presented to convert a 3D surface fitting problem into a two-dimensional (2D) curve fitting problem, and achieve fast solution for the surface normal vector of the incident point. Compared with least squares polynomial fitting method, this method improves computational accuracy and efficiency of the ion incidence angle. The improvement on the accuracy of fitting is achieved by improving the selection method of surface cellular for fitting. The fitting method is applied to 3D simulation of silicon etching process, and the simulation results verify the simulated surface by comparing with relevant experimental results.
A new approach to fabricating silicon nanowire/poly(3, 4-ethylenedioxythiophene) hybrid heterojunction solar cells
Authors: Li Xiao-Juan  , Wei Shang-Jiang  , Lü Wen-Hui  , Wu Dan  , Li Ya-Jun  , Zhou Wen-Zheng  ,   College of Physics Science and Technology, Guangxi University, Nanning 530004, China;,   i-LAB, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215125, China;,   Department of Physics, Zhanjiang Normal University, Zhanjiang 524048, China
Published: December 2020

The silicon/poly(3, 4-ethylenedioxythiophene) core/shell organic/inorganic nanowire array (SiNWs/PEDOT) hybrid heterojunction solar cells are successfully fabricated by silver-assisted chemical etching method and vapor phase polymerization processes. The SiNWs/PEDOT hybrid solar cell shows that the performance is improved greatly and an excellent power conversion efficiency of 3.23% is achieved, which is as seven times as large as that of the planar cell without the nanowire structure. In addition, the studies of the reflectance, the I-V curve and the external quantum efficiency show that the great enhancement of performance for the SiNWs/PEDOT cell is due to the fact that the Si/PEDOT core/shell nanowire structure is successfully fabricated by vapor phase polymerization method, resulting in a high light trapping effect, a large junction area and an enhancement of the carrier collection efficiency.
Analysis of the spreading influence of the nodes with minimum K-shell value in complex networks
Authors: Ren Zhuo-Ming  , Liu Jian-Guo  , Shao Feng  , Hu Zhao-Long  , Guo Qiang  ,   Complex Systems Science Research Center, University of Shanghai for Science and Technology, Shanghai 200093, China
Published: December 2020

The K-shell decomposition for identifying influential nodes plays an important role in analyzing the spreading performance in complex networks, which generates lots of nodes with the smallest K-shell value. The spreading influences of these nodes cannot be distinguished by the K-shell decomposition method, as well as the degree and betweeness indices. In this paper, by taking into account the K-shell information of the target node, we develop a new method to identify the node spreading ability with the minimum K-shell value. The experimental results for pretty good privacy and autonomous system networks show that the presented method could generate more accurate spreading list than the degree and betweeness indices.
The application of ensemble empirical mode decomposition method in multiscale analysis of region precipitation and its response to the climate change
Authors: Xue Chun-Fang  , Hou Wei  , Zhao Jun-Hu  , Wang Shi-Gong  ,   Department of Atmospheric Sciences, Lanzhou University, Lanzhou 730000, China;,   National Climate Center, Beijing 100081, China;,   Shaanxi Provincial Meteorological Bureau, Xi'an 710014, China
Published: December 2020

Recently, ensemble empirical mode decomposition (EEMD) method has been developed for non-linear and non-stationary signal analysis. The method can work on nature signals (non-linear and nonstationary signals) and reduce the speckle noise. With the EEMD method, the signal is decomposed into several intrinsic mode functions (IMFs) and the frequencies of IMFs are arranged in decrease order (high to low) after the EEMD processing. The scaling mode of the EEMD method is similar to wavelet transform, but the signal resolutions in different frequency domains do not decrease by down-sampling. There are a large population and a developed economy in Weihe watershed, the disasters of droughts and floods caused by the autumn precipitation (here is precipitation in September and October) less or more than normal cause great loss and serious influence. In this paper, we propose the EEMD method to decompose the autumn precipitation series in the Weihe river basin during last 50 years into several IMFs, then extract the information including in the precipitation series and get the characteristics of multi-scales. The result shows that it is well response to the autumn precipitation series in the Weihe river basin and to the abrupt climate change in late 1970s and early 1980s of last century. The response appears earlier for high time scales than for low time scales In addition, the expression of the response for high time scales is the form of variability, but it is the amplitude of variability for low time scales.
Solution of the transfer models of femtosecond pulse laser for nano metal film
Authors: Han Xiang-Lin  , Zhao Zhen-Jiang  , Cheng Rong-Jun  , Mo Jia-Qi  ,   Faculty of Science, Huzhou Teacher College, Huzhou 313000, China;,   Ningbo Institute of Technology, Zhejiang University, Ningbo 315100, China;,   Department of Mathematics, Anhui Normal University, Wuhu 241000, China
Published: December 2020

A class of transfer models for femtosecond pulse laser on nano metal film has been investigated. First, we solve the reduced solution. And then, the arbitrary order asymptotic solution of corresponding model is obtained by using the perturbation theory and method. Finally, the behavior of the solution is discussed.
Static and dynamic analysis of elastic shell structures with smoothed particle method
Authors: Ming Fu-Ren  , Zhang A-Man  , Yao Xiong-Liang  ,   College of Shipbuilding Engineering, Harbin Engineering University, Harbin 150001, China
Published: December 2020

Meshfree smoothed particle method has great advantages in dealing with nonlinear problems of solid structures However, due to the instability and poor accuracy, it has been limited to the application in solid mechanics for a long time; especially the study on shell structure with smoothed particle method is even rarely reported on account of expensive three-dimensional continuum modeling and the phenomenon of numerical fracture in the traditional method The moving least square function and total Lagrangian equations are introduced as an approximation function and approximation equations respectively to improve the stability and numerical accuracy of smoothed particle method; on this basis, the method of static analysis is proposed, and meanwhile the dynamic analysis method is also refined. Finally, the internationally recognized standard test models on static and dynamic problems are adopted to verify the above shell theory, and the results are in good agreement with the existing data, which proves the validity and reliability of the present numerical model. This paper aims to provide a reference for the further research of smoothed particle method on nonlinear shell structures, such as crack, crushing, etc.
Off-diagonal Berry phase in nonlinear systems
Authors: Yang Zhi-An  ,   School of Physics and Technology, University of Jinan, Jinan 250022, China
Published: December 2020

In this paper, we have investigated the off-diagonal Berry phase of nonlinear systems and presented its explicit expression. The results show that, for nonlinear systems, the off-diagonal berry phase contains a new term in addition to the dynamical phase, the geometric phase and the nonlinear phase. This new term can describe a cross effect between the Bogoliubov excitation around one eigenstate and another instantaneous eigenstate, while the Bogoliubov excitations are found to be accumulated during the adiabatic evolution and contribute a finite phase of geometric nature. As an application, the off-diagonal Berry phase of a two-well trapped Bose-Einstein condensate system is calculated.
Nonliner Landau-Zener tunneling of a Bose-Fermi mixture
Authors: Zhang Heng  , Wang Wen-Yuan  , Meng Hong-Juan  , Ma Ying  , Ma Yun-Yun  , Duan Wen-Shan  ,   College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070, China
Published: December 2020

In this paper we study the nonlinear Landau-Zener tunneling of a boson-fermion mixture in a double-well potential by adjusting the interaction parameter of its components. We find that the tunneling in the system can be affected by adjusting the interatomic self-interaction parameter. Moreover, we notice that the tunneling in the system show a critical phenomenon if variation of interatomic self-interaction, and critical point are given.
Effect of non-Gaussian noise on negative mobliity
Authors: Yang Bo  , Mei Dong-Cheng  ,   Department of Physics, Yunnan University, Kunming 650091, China
Published: December 2020

Effects of non-Gaussian noise on negative mobility in an inertial ratchet were investigated by means of stochastic simulation method. The absolute negative mobility (ANM), negative nonlinear mobility (NDM), and negative differential mobility (NNM) were simulated, separately. Results indicate that: (i) non-Gaussian noise can either enhance or diminish the phenomena of ANM, and non- Gaussian noise also can induce NDM and NNM in regions of parameter space. (ii) The average velocity-correlation time characteristics shift towards small value of correlation time. (iii) The absolute value of negative-valued minima decreases as the non-Gaussian noise parameter q increases.
Equivalent modeling and bifurcation analysis of V2 controlled buck converter
Authors: He Sheng-Zhong  , Zhou Guo-Hua  , Xu Jian-Ping  , Bao Bo-Cheng  , Yang Ping  ,   School of Electrical Engineering, Southwest Jiaotong University, Chengdu 610031, China;,   School of Information Science and Engineering, Changzhou University, Changzhou 213164, China
Published: December 2020

After dimension reduction, two boundary voltages of V2 controlled buck converter are deduced under different operation mode, based on which, its equivalent one-dimensional discrete-time model is established and complex nonlinear bifurcation behaviors are emphatically studied. Two boundary conditions under which shift between stable period-one state and subharmonic oscillation state and shift between continuous conduction mode (CCM) and discontinuous conduction mode (DCM) take place are derived by analyzing stability and operation mode. The research results show that in V2 controlled buck converter period-doubling bifurcation and border-collision bifurcation can occur with varying circuit parameters and the converter has different bifurcation routes at different circuit parameters. Simulation and experiment platforms are implemented and the corresponding results verify the validity of equivalent discrete-time model and theoretical analysis.
Study on nonlinear phenomena in single phase H bridge inverter based on the periodic spread spectrum
Authors: Liu Hong-Chen  , Li Fei  , Yang Shuang  ,   School of Electrical Engineering and Automation, Harbin Institute of Technology, Harbin 150001, China
Published: December 2020

The periodic spread spectrum technologies used in converter to suppress its electromagnetic interference and noise have been applied widely, while the nonlinear phenomenon is ignored. Based on the analysis of the periodic spread spectrum technology and single-phase H bridge converter accurate stroboscopic map model, the bifurcation and chaos phenomenon of the single-phase H bridge circuit is studied and the discrete model of the H bridge sine inverter is established by means of periodic spread spectrum technology. The nonlinear phenomenon is analyzed using the time domain chart, folding map, bifurcation diagram and Lyapunov index spectrum. Results show that the H bridge sine inverter based on the spread spectrum technology can go into the chaotic region more easily when it is in the nonlinear region, and it is concluded that the frequency of cycle spread spectrum has important effect on the initial branch point position of system.
Delay time obtaining method using the maximum joint entroy on the basis of symbolic analysis
Authors: Zhang Shu-Qing  , Li Xin-Xin  , Zhang Li-Guo  , Hu Yong-Tao  , Li Liang  ,   Institute of Electronic engineering of Yanshan University, Qinhuangdao 066004, China
Published: December 2020

In this paper, the local maximum of joint entroy was computed using the symbolic analysis method so as to determine the appropriate delay time of the phase space reconstruction. The numerical experiments for three typical chaotic systems show that the present method could reduce computation, increase the efficiency, and also could obtain the optimum delay time accurately and rapidly. And it could reconstruct the original phase space from the time series effectively. Thus it provides a fast and effective way to identify the chaotic signal.
Limited penetrable visibility graph from two-phase flow for investigating flow pattern dynamics
Authors: Gao Zhong-Ke  , Hu Li-Dan  , Zhou Ting-Ting  , Jin Ning-De  ,   School of Electrical Engineering & Automation, Tianjin University, Tianjin 300072, China
Published: December 2020

We optimize and design a new half-ring conductance sensor for measuring two-phase flow in a small diameter pipe. Based on the experimental signals measured from the designed sensor, we using the limited penetrable visibility graph we proposed construct complex networks for different flow patterns. Through analyzing the constructed networks, we find that the joint distribution of the allometric scaling exponent and the average degree of the network allows distinguishing different gas-liquid flow patterns in a small diameter pipe. The curve peak of the degree distribution allows uncovering the detailed features of the flow structure associated with the size of gas bubbles, the average degree of the network can reflect the macroscopic property of the flow behavior, The allometric scaling exponent is very sensitive to the complexity of fluid dynamics and allows characterizing the dynamic behaviors in the evolution of different flow patterns. In this regard, limited penetrable visibility graph analysis of fluid signals can provide a new perspective and a novel tool for uncovering the dynamical mechanisms governing the formation and evolution of different flow patterns.
Time-controllable projective synchronization of a class of chaotic systems based on adaptive method
Authors: Wang Chun-Hua  , Hu Yan  , Yu Fei  , Xu Hao  ,   College of Information Science and Engineering, Hunan University, Changsha 410082, China
Published: December 2020

To solve the problem of indeterminate synchronization time in different chaotic systems, this paper presents a time-controllable synchronization scheme. A general synchronization controller and parameter update laws are proposed to stabilize the error system, thus the drive and response systems could be synchronized up to a given scaling matrix at a pre-specified exponential convergence rate. The synchronization time formula is strictly deduced, which suggests that the speed of synchronization is determined by several parameters, such as exponential rate, initial system value and other parameters brought in by the controller. By adjusting these parameters, the performance of the synchronization can be effectively improved. In numerical simulation, two nonidentical 3D autonomous chaotic systems are chosen to verify this method. The error system can be rapidly stabilized, and unknown parameters are also identi?ed correctly. Firally, two groups of time-controllable parameters are given to verify the theory, wherein synchronization of both cases can be obtained quickly and each result of the synchronization is consistent with the theoretical calculation. The synchronization scheme is characterized by high safety and efficiency, and has its potential value in secure communication.
The numerical-aperture-dependent optical contrast and thickness determination of ultrathin flakes of two-dimensional atomic crystals: A case of graphene multilayers
Authors: Han Wen-Peng  , Shi Yan-Meng  , Li Xiao-Li  , Luo Shi-Qiang  , Lu Yan  , Tan Ping-Heng  ,   State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors Chinese Academy of Sciences, Beijing 100083, China
Published: December 2020

The optical and electronic properties of two-dimensional atomic crystals including graphene are closely dependent on their layer numbers (or thickness). It is a fundamental issue to fast and accurately identify the layer number of multilayer flakes of two-dimensional atomic crystals before further research and application in optoelectronics. In this paper, we discuss in detail the application of transfer matrix method to simulate the optical contrast of ultrathin flakes of two-dimensional atomic crystals and further to identify their thickness, where numerical aperture of microscope objective is considered. The importance of numerical aperture in the thickness determination is confirmed by the experiments on the graphene flakes. Furthermore, two lasers with different wavelengths can be serviced as light sources for the thickness identification of flakes of two-dimensional atomic crystals with a size close to the diffraction limit of the microscope objective. The transfer matrix method is found to be very useful for the optical-contrast calculation and thickness determination of flakes of two-dimensional atomic crystals on multilayer dielectric substrate.
A non-linear analysis for gamma-ray spectrum based on compressed sensing
Authors: Feng Bing-Chen  , Fang Sheng  , Zhang Li-Guo  , Li Hong  , Tong Jie-Juan  , Li Wen-Qian  ,   Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 10084, China
Published: December 2020

The gamma-ray spectrum analysis is an important method for quantitative analysis of radionuclide. Although widely used, the weak peak identification and overlapping peaks resolution are still difficult for gamma-ray spectrum analysis. To solve the problem, a new method based on compressed sensing is proposed for improving gamma-ray spectrum analysis in this paper. The proposed method models physical modulation of gamma spectrometer as a linear equation, and formulates the gamma-ray spectrum analysis as a corresponding inverse problem. The true gamma spectrum is obtained by solving the inverse problem by applying sparsity constraint under the framework of compressed sensing. The feasibility of the proposed method is demonstrated by both numerical simulation and Monte Carlo simulation experiments. Results demonstrate that the proposed method can simultaneously resolve overlapped peaks and reduce the fluctuations of gamma-ray spectrum, effectively improving the accuracy of gamma-ray spectrum analysis.
Study on spectroscopic properties and molecular constants of the ground and excited states of AsCl free-radical
Authors: Zhu Zun-Lue  , Lang Jian-Hua  , Qiao Hao  ,   College of Physics and electronic Engineering, Henan Normal University, Xinxiang 453007, China
Published: December 2020

The dissociation limit of AsCl free-radical is correctly determined based on group theory and atomic and molecular statics. Potential energy curves (PECs) for the ground state and several low-lying electronic excited states of AsCl free-radical are calculated using the multi-reference configuration interaction method with the basis set of aug-cc-pV5Z where the Davidson correction is considered as an approximation to full CI. Separation parameters (Re, e, ee, D0, De, Be and e) are evaluated using the PEC of AsCl. Spectroscopic parameters are compared with those reported in the literature, and excellent agreement is found between them. With the PEC of AsCl free-radical, forty vibrational states of AsCl free-radical are predicted when J=0 by numerically solving the radial Schrdinger equation of nuclear notion. For each vibrational state, the vibrational levels and inertial rotation constants are reported.
Simulation of electromagnetic soliton radiography under laser-produced proton beam
Authors: Teng Jian  , Zhu Bin  , Wang Jian  , Hong Wei  , Yan Yong-Hong  , Zhao Zong-Qing  , Cao Lei-Feng  , Gu Yu-Qiu  ,   Science and Technology on Plasma Physics Laboratory, Laser Fusion Research Center, China Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

During propagating through an underdense plasma, a laser will experience significant energy loss and will be trapped in the plasma as the frequency undergoing a redshift. Thus the electromagnetic (EM) soliton is formed. EM field distribution at different stage is constructed for the soliton in terms of primary theory and particle in cell (PIC) simulation. Radiography of solitons produced by laser accelerated MeV protons is investigated using Monte Carlo methods. The influencing fact or such as proton energy and source size is analyzed. Time-resolved radiography of the soliton is also carried out as the protons accelerated by the target normal sheath acceleration (TNSA) mechanism have a wide energy spectrum. Results validate the static electric field model of the soliton, and provide the basis for the future experiments.
The modeling of end pumping Yb3+:YVO4 quasi-three-level laser
Authors: Xia Zhong-Chao  , Yang Fu-Gui  , Qiao Liang  ,   Fujian Jiangxia University, Fuzhou 350108, China
Published: December 2020

In a Yb3+ laser, the two-energy level structure is close to the quasi-three-level model, but different from that for the Nd and Tm lasers, so it is necessary to investigate the quasi-three-level modeling that will be applied to the Yb3+ laser. Based on the energy level structure, cavity gain and loss as well as population distribution, we present the modeling. Introducing an effective cavity length factor, the laser intensity is calculated and the threshold is obtained. Comparison with the experiments, indicates that the effective cavity length ratio changes the fractional population function and loss, which would influence the threshold and output in turn. Applied to investigate the laser property in the process of end pumping Yb3+:YVO4 laser, we get the threshold being 1.1 W, corresponding to the L=1 mm and T=1%; whereas the threshold is 3.9 W, corresponding to the L=2 mm and T=10%.
Numerical investigation on the characteristics of the mushroom-like vortex structure generated by a submerged laminar round jet
Authors: Chen Yun-Xiang  , Chen Ke  , You Yun-Xiang  , Hu Tian-Qun  ,   State Key Laboratory of Ocean Engineering, ShanghaiJiaoTongUniversity, Shanghai 200240, China
Published: December 2020

A numerical investigation on the evolution mechanism and characteristics of the submerged laminar round jet in a viscous homogenous fluid is conducted by using the computational fluid dynamics method based on the incompressible Navier-Stokes equation. Three non-dimensional parameters for the mushroom-like vortex structure, including the length of the jet L*, the radius of the mushroom-like vortex R* and the length of vortex circulation d*, are introduced and the variation characteristics of these parameters with the non-dimensional time t* are quantitatively analyzed. Results show that there exist three distinct stages in the formation and evolution procedures of the mushroom-like vortex structure, including the starting, developing and decaying stages. In the starting stage, L* and d* increase linearly with t*, while R* approximately remains to be a constant; in the developing stage, a considerable self-similarity is confirmed, and L*, R*, d* display the same proportional relationship to t*1/2 regardless of the variations of Reynolds number and injection duration; in the decaying stage, L* and R*are approximately proportional to t*1/5, while d* nearly levels off as a constant. Moreover, velocity characteristics at the secondary backflow point and the momentum and geometry centers, the distribution features of the vertical vorticity, as well as the vorticity-stream function relationship are analyzed for the mushroom-like vortex structure.
The motion and acoustic radiation characteristics for cavitation in the compressible vortex fluid
Authors: Ye Xi  , Yao Xiong-Liang  , Zhang A-Man  , Pang Fu-Zhen  ,   College of Shipbuilding Engineering, Harbin Engineering University, Harbin 150001, China
Published: December 2020

Based on the compressible fluid theory, the boundary integral equation is used to solve the motion law of cavitation in vortex flow within different surface pressure models. The time-domain sound pressure characteristics induced by cavitation in vortex field are obtained by the moving surface Kirchhoff formulation. With the surface discretion and coordinate transformation, the cavitation surfaces are treated as the moving deformable boundary and the acoustic source directly. The influence of vortex field parameters on motion and radiation of cavitation is analyzed. Results show that with the consideration of compression, the amplitude of cavitation's pulsation as well as the sound pressure will be decreased. In the vortex fluid, cavitation will be extended, necked and splitted, and may generate a jet in sub-bubbles. While the pressure is reduced in the fluid field, the maximum radius and length before splitting of the cavitation will be enlarged. The number of sub-bubbles will increase when the pressure is small in the fluid field. The directive property of cavitation is weak. And the splitting of cavitation will generate a great peak value of sound pressure. With the increase in vortex flux or the decrease in the cavity number, the period of the cavitation oscillation and its radiation sound pressure are elongated, and the peak of sound pressure is retarded and reduced. The results in this paper could be used as the reference data for the research about the motion and sound radiation characteristics of cavitation in vortex fluid.
Effect of thickness on the properties of Cu(Inx,Ga1-x)Se2 back conduct Mo thin films prepared by DC sputtering
Authors: Tian Jing  , Yang Xing  , Liu Shang-Jun  , Lian Xiao-Juan  , Chen Jin-Wei  , Wang Rui-Lin  ,   College of materials science and engineering, Sichuan University, Chendu 610065, China
Published: December 2020

In this study, Mo thin films which used in Cu(Inx Ga1-x)Se2 (CIGS) thin film solar cells as back conduct were deposited on soda-lime glass substrates via DC magnetron sputtering under certain conditions. A series of Mo thin films prepared of various thicknesses was obtained in different sputtering deposition times. The microstructure, electrical resistivity and mechanical strain property of Mo thin films, which may be varied by controlling the thickness, were investigated by XRD, SEM, four probes technology and Scotch tape test. As the results showed, the thicknesses of the films increased linearly with the sputtering time. With increasing thickness, the films' crystal growth showed a change from (110) preferred orientation to (211) preferred orientation. The sheet resistance sharply reduced to 2 Ω/⇑ with the increase of (110) peak height and the resistivity linearly decreased to 0.96×10-4 Ω·cm due to the level of (110) preferred orientation. The films surface has porous (fish-like) grain morphology and intergranular voids. All the films are in a tensile state, and the inner strain decreased with the increase of the thickness.
The site preference of refractory element W in NiAl dislocation core and its effects on bond characters
Authors: Chen Li-Qun  , Yu Tao  , Peng Xiao-Fang  , Liu Jian  ,   College of Science, Central South University of Forestry and Technology, Changsha 410004, China;,   Division of Functional Materials, Central Iron and Steel Research Institute, Beijing 100081, China
Published: December 2020

The site occupancy of refractory element W in the (010) edge dislocations of NiAl intermetallic compounds and its effect on NiAl properties are studied by the first-principles discrete variational method. The energetic parameters (binding energy, the impurity segregation energy and the interatomic energy), the density of states and the charge density are calculated respectively for the clean dislocation system and the doped dislocation system. The calculated results of the binding energy and the impurity segregation energy suggest that W exhibits a strong Al site preference. The interactions between the refractory elements W and the neighbouring host atoms are strengthened due mainly to the hybridization of 4d orbital of impurity atom and 3d orbital of host Ni atoms (3p orbital of host Al atom). Meanwhile, some charge accumulations appear between impurity atom and neighbouring host atoms in the dislocation core, indicating that strong bonding states are formed between the impurity atom and its neighbouring host atoms. The refractory element W greatly affects the energy and the electronic structure of NiAl intermetallic compounds, and in turn influences the motion of dislocation and the properties of NiAl compound.
The spectrum-control of dual-wavelength LED with quantum dots planted in quantum wells
Authors: Zhang Pan-Jun  , Sun Hui-Qing  , Guo Zhi-You  , Wang Du-Yang  , Xie Xiao-Yu  , Cai Jin-Xin  , Zheng Huan  , Xie Nan  , Yang Bin  ,   Laboratory of Nanophotonic Functional Materials and Devices, Institute of Opto-Electronic Materials and Technology, South China Normal University, Guangzhou 510631, China
Published: December 2020

A theoretical simulation of electrical and optical characteristics of GaN-based dual-wavelength light-emitting diodes (LED) with high In content in the quantum dots (QDs) which are planted in quantum wells is conducted with APSYS software. The adjustment and contrast of the structure of the devices showed that the blue and green dual-wavelength LEDs will have a broader radiation spectrum and a higher color rendering index when QDs are planted in the green quantum wells. QDs have strong blinding capacity with the carriers, and the carriers at the QDs have shorter lifetime than they are in the wetting layers, so the carrier recombination will give preference to the QDs. It is shown that the distribution of the carriers could be easily controlled by adjusting the spacing layer thickness and the spacing layer doping concentration, so as to control the radiation rate of the two active layers of the dual-wavelength LEDs. Therefore, the spectrum-control of the dual-wavelength LED with QDs planted in QWs could be realized by adjusting the concentration of quantum dots, the thickness of the spacing layer and the doping concentration in the spacing layer. This article can provide guidance for the realization of the non-phosphor white LED.
Ultralow-voltage in-plane-gate indium-tin-oxide thin-film transistors made of P-doped SiO2 dielectrics
Authors: Zhu De-Ming  , Men Chuan-Ling  , Cao Min  , Wu Guo-Dong  ,   School of energy and power engineering, University of Shanghai for Science and Technology, Shanghai 200093, China;,   Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China
Published: December 2020

A new kind of indium-tin-oxide thin-film transistors made of P-doped SiO2 dielectrics in an in-plane-gate structure is fabricated at room temperature. Indium-tin-oxide (ITO) channel and ITO electrodes (gate, source, and drain) can be deposited simultaneously without precise photolithography and alignment process by using only one nickel shadow mask. So the thin film transistors (TFTs) have a lot of advantages, such as the simple device process、low cost etc. Such TFTs exhibit a good performance at an ultralow operation voltage of 1 V, a high field-effect mobility of 18.35 cm2/Vs , a small subthreshold swing of 82 mV/decade, and a large on-off ratio of 1.1×106, because of the huge electric-double-layer (EDL) capacitance (8 μF/cm2) between the interface of P-doped SiO2 dielectrics and ITO channel. So the TFTs are very promising for the application of low-power and portable electronic products and sensors in the future.
Influence of applied magnetic field on properties of silicon nitride thin film with light trapping structure prepared by R.F. magnetron sputtering
Authors: Jiang Qiang  , Mao Xiu-Juan  , Zhou Xi-Ying  , Chang Wen-Long  , Shao Jia-Jia  , Chen Ming  ,   School of Material Engineering, Shanghai University of Engineering Science, Shanghai 201620, China
Published: December 2020

In the applied magnetic field different magnetic intensities in the permanent magnet were introduced between the substrate and target, so as to study their influence on the properties of silicon thin films with light trapping structure prepared by R.F. magnetron sputtering. The microstructures, surface morphology and optical properties of the films were characterized by X-ray diffraction, atomic force microscope (AFM) and ultraviolet spectrophotometer separately. Results show that the silicon nitride thin films are still in amorphous state although an magnetic field was applied on them; however, when the magnetic field in the center is of 1.5 T, the surface morphology of the films has dramatically changed to a special peak structure, i.e. pyramid-like protuberances which are perpendicular to the basal surface; meanwhile, in the visible and near infrared range, the average transmittance of the sample is the highest, which is more than 90%, nearly twice as much as the transmittance of the sample without applied magnetic field, thus the light trapping effect is the great.
Nonlinear integrable couplings of super Kaup-Newell hierarchy and its super Hamiltonian structures
Authors: Wei Han-Yu  , Xia Tie-Cheng  ,   Department of Mathematics, Shanghai University, Shanghai 200444, China;,   Department of Mathematics and Information Science, Zhoukou Normal University, Zhoukou 466001, China
Published: December 2020

Based on a kind of new Lie superalgebras, we introduce the general method of constructing the nonlinear integrable couplings of super soliton hierarchy. Super trace identity over the corresponding loop superalgebras is used to obtain the super Hamiltonian structures for the resulting nonlinear integrable couplings of the super soliton hierarchy. As an application, we give the nonlinear integrable couplings of super Kaup-Newell hierarchy and its super Hamiltonian structures. This method can be generalized to other super soliton hierarchy.
Modeling of the interaction between solidification interface and bubble using the lattice Boltzmann method with large density ratio
Authors: Chen Hai-Nan  , Sun Dong-Ke  , Dai Ting  , Zhu Ming-Fang  ,   Jiangsu Key Laboratory for Advanced Metallic Materials, Southeast University, Nanjing 211189, China;,   School of Mechanical Engineering, Southeast University, Nanjing 211189, China
Published: December 2020

A two-dimensional (2D) two-component and two-phase lattice Boltzmann method (LBM) with large density ratio is developed based on a modified Shan-Chen pseudopotential model combined with the deferent time step method. The present LBM model can simulate the gas-liquid two-phase flow with density ratio up to around 800. To validate the model, the pressure difference between the inside and outside of a bubble varying with its radius is simulated with different gas-liquid interact parameters and density ratios. The results are found to obey the Laplace law. Then, the LBM is coupled with the cellular automaton (CA) method used for simulating the solid phase growth, and the finite difference method (FDM) used for calculating the temperature field. The LBM-CA-FDM coupled model is used to simulate the interaction between bubble and the solidification interface. The results show that the existence of adiabatic bubble influences the distribution of temperature field in front of solidification interface, which leads to a bulge of the solid-liquid interface when it is close to the bubble. Under the conditions of different growth rates, the bubble is either engulfed or pushed away by the growing solid-liquid interface. The simulation results agree reasonably well with those observed experimentally.
Application of a fractional algorithm to studying the competition between dissipation and fluctuation in non-Markov process
Authors: Lin Fang  , Hu Dan-Qing  , Li Le-Le  ,   College of Physical Science and Technology, Sichuan University, Chengdu 610064, China
Published: December 2020

Based on fractional Langevin equation and random walk theory, a numerical algorithm that can be applied to non-Markov long-memory system is established in this paper. In addition, the evolution behaviour of random variable ruled by fractional sub-diffusion equation is numerically studied in three conditions: no dissipation, no fluctuation and both being present. The results show that competition exists between dissipation and fluctuation. As time goes by, the effect of Guassian fluctuation weakens and damping plays a main role in the evolution of system; however, because of the existance of "rare-though-dominant" events, long-tail fluctuation makes the evolution of system abrupt change at a certain probability.
Rules for predicting regime change in the Lorenz chaotic system based on the Lorenz map
Authors: Li Ai-Bing  , Zhang Li-Feng  ,   College of Meteorology and Oceanography, PLA University of Science and Technology, Nanjing 211101, China
Published: December 2020

Corresponding to two strange Lorenz attractors, in the Lorenz model there exist two opposite regimes which can be called as positive and negative regimes. Despite the trajectory of the Lorenz system changing between the two regimes back and forth with an unfixed period, the regime change is predictable. In this paper, with the help of the Lorenz map, three rules for predicting regime change are obtained. In particular, besides two generic predictable rules for the condition of regime transition and duration in new regime, a new rule about length for reaching transition condition, which has not been reported in previous work, is also very important. It provides another approach to forecasting the evolution of the nonlinear dynamical system. The results show that the position for highest point in cusps is the critical value for regime change. When the value of variable z is greater than the corresponding critical value, the current regime is about to end, and the Lorenz model will move to other regime in the next cycle. The length for reaching transition condition in the current regime decreases monotonically with local maximum value zmax, and the smaller zmax in current status implies the bigger length for reaching transition condition. The duration in new regime increases monotonically with the maximum value zM in the previous regime, and the bigger the value of zM, the larger the range for the duration increase is. In addition, the forcing is also associated with the prediction rules for regime change. It not only makes transition conditions for positive and negative regimes different, but also determines the speed of decrease in length for reaching transition condition and the range of increase for duration in new regime.
Bifurcation analysis of complex behavior in the Logistic map via periodic impulsive force
Authors: Jiang Hai-Bo  , Li Tao  , Zeng Xiao-Liang  , Zhang Li-Ping  ,   School of Mathematics, Yancheng Teachers University, Yancheng 224002, China
Published: December 2020

The complex dynamics of the Logistic map via two types of periodic impulsive forces is investigated in this paper. With the parameter varying, the system produces the phenomenon such as equilibrium solutions, periodic solutions, and chaotic solutions. Furthermore the system can evolve into chaos by a cascading of period-doubling bifurcations. The Poincaré map of the Logistic map via periodic impulsive force is constructed and its bifurcation is analyzed. Finally, the Floquet theory is used to explore the bifurcation mechanism for the periodic solutions.