bluuebunny/crossref_metadata_2025 huggingface dataset:
Small perturbed solution for a class of sea-air oscillator model
Authors: Han Xiang-Lin  , Shi Lan-Fang  , Mo Jia-Qi  ,   Departmentt of Mathematics, Huzhou Teachers College, Huzhou 313000, China;,   College of Mathematics and Statistics, Nanjing University of Information Science and Technology, Nanjing 210044, China;,   Department of Mathematics, Anhui Normal University, Wuhu 241003, China
Published: December 2020

In this paper, we create an asymptotic method of solving the nonlinear equation for the sea-air oscillator model. And based on a class of oscillator of the sea-air oscillator model. We first expanding the time delay, then discussing the relative values for the small parameters in the case of three copies, and finally, obtain uniformly valid asymptotic expansion by using the theory of the differential inequity.
The influence of different driving patterns on parity time-reversal symmetry
Authors: Chen Xi  , Yu Whitney  , Joglekar Yogesh N  , Zheng You-Qu  , Xu You-Sheng  , Wu Feng-Min  ,   Department of Physics, Zhejiang Normal University, Jinhua 321004, China;,   Department of Mechanical Engineering, Indiana University-Purdue University Indianapolis (IUPUI), Indiana 46202, USA;,   Department of Physics, Indiana University-Purdue University Indianapolis (IUPUI), Indiana 46202, USA;,   Zhejing University of Science and Technology, Hangzhou 310023, China
Published: December 2020

In the past few years, the balanced sink and source macroscopic open system, which satisfies the parity and time-reversal symmetry, has become a research hot point. We introduce parity and time-reversal (PT) symmetry into fluid system by setting up balanced inflow and outflow in a two-dimensional channel. The flow is governed by Navier-Stokes equation and we use lattice Boltzmann method to solve them. Defining configuration-dependent asymmetric functions in velocity, kinetic energy density, and vorticity fields, we find that the PT function of the flow increases with the increase of the 2th power of Reynolds number i.e., ρn～ Ren. In this work, we use three different velocity profiles to drive the flow. It is demonstrated that in the three driven modes, the power-law schedule holds true. It is concluded that PT asymmetry of the viscous flow is determined by the flow dynamics not by the driven modes, thereby verifies the universality of the power-law scaling in viscous flow with balanced inflow and outflow.
Substrate effect on surface-electrode ion trap and hybrid design for ion trap
Authors: Zhang Jian  , Chen Shu-Ming  , Liu Wei  ,   College of Computer, National University of Defense Technology, Changsha 410073, China;,   Science and Technology on PDL, National University of Defense Technology, Changsha 410073, China
Published: December 2020

To analyze the trap depth and ion heating rate of a surface ion trap under the influence of substrate power loss and voltage loss, in this paper we proposes analytic expressions of trap depth and ion heating rate. The results show that the voltage loss of Si substrate can reduce the trap depth by 17.19%, and the power loss would accelerate the ion heating rate by 13.37%. In order to reduce the influence of substrate effect, a new surface ion trap with low self-heating and voltage-loss is proposed in this paper, whose substrate is insulated by some vacuum trench to reduce the equivalent conductivity and capacitance. The simulation results illuminate that compared with the surface ion trap with normal Si-SiO2 substrate, the one with vacuum trench insulation exhibits a 20.22% increase in trap depth and a 54.44% reduction in power loss.
Implementation of a new chaotic system based on field programmable gate array
Authors: Shao Shu-Yi  , Min Fu-Hong  , Wu Xue-Hong  , Zhang Xin-Guo  ,   School of Electrical and Automation Engineering, Nanjing Normal University, Nanjing 210042, China;,   School of Information Science and Engineering, Lanzhou University, Lanzhou 730000, China
Published: December 2020

A new five-dimensional modified Chua’s system is proposed and its dynamic properties are investigated through numerical simulations, the stabilization of equilibrium points, bifurcation diagrams, and Lyapunov exponent spectrum. The different dynamic behaviors of the new system are analyzed with system parameters changed. Based on the mathematical model of the new system and the digital processing technology, the five-dimensional modified Chua’s system is discretized. According to IEEE-754 standard and module-based design idea, basic floating-point operational modules are designed. Furthermore, the chaotic attractors of the five-dimensional modified Chua’s system are realized by field programmable gate array. The investigation results show that the chaotic system is different from the existing chaotic systems. It also shows a good agreement between numerical simulation and hardware implementation, which proves the existence and realizability of the new chaotic system.
Feedback control and linear generalized synchronization of spatial-alternated Julia sets
Authors: Wang Pei  , Liu Shu-Tang  ,   College of Control Science and Engineering, Shandong University, Jinan 250061, China
Published: December 2020

In this paper, the spatial-alternated Julia sets are discussed, which are obtained by alternated iteration of quadratic family zm+1,n+azm,n+1=(1+a)2zmn2+ci,i=1,2. The control of spatial-alternated Julia sets is accomplished by using the feedback control. Then the linear generalized synchronization of two different spatial-alternated Julia sets is discussed. The simulations demonstrate the effectiveness of the control methods.
Nanometer film thickness metrology and traceability based on grazing incidence X-ray reflectometry
Authors: Cui Jian-Jun  , Gao Si-Tian  ,   State Key Laboratory of Precision Measuring Technology and Instruments (Tianjin University), Tianjin 300072, China;,   National Institute of Metrology, Beijing 100013, China
Published: December 2020

To realize metrology of the nanometer thin film thickness with high accuracy, a series of the nanometer film thickness standard samples with single layer is developed which could be measured by contact instruments such as stylus contact surface step profiler and scanning probe microscopy. The measurement and calculation method of grazing incidence X-ray reflectometry (GIXRR) for film thickness are studied. The formula of linear fitting method based on the periodic Kiessig fringes for thickness measurement is presented. A tracing approach of film thickness measurement, which is traceable to the atomic lattice of monocrystalline silicon and national angle standard, is proposed, and a new optics calibration method is presented which can measure angular misalignment of GIXRR apparatus. The relative expanded uncertainty of the nanofilm thickness H measurement is U=0.3 nm+1.5%H with coverage factor k=2.
Novel improved blind detection algorithms based on chaotic neural networks
Authors: Yu Shu-Juan  , Huan Ru-Song  , Zhang Yun  , Feng Di  ,   College of Electronic Science and Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210003, China;,   China Mobile Group Jiangsu Company Limited Suzhou Branch, Suzhou 215002, China
Published: December 2020

In this paper we apply the transiently chaotic Hopfield neural networks (TCHNN) to the blind signal detection algorithm with BPSK signals and solve multi-start problem of Hopfield neural networks (HNN). And in this paper we propose an improved algorithm of double sigmoid transiently chaotic Hopfield neural networks (DS-TCHNN) on the basis of TCHNN, construct a new energy function of DS-TCHNN, and prove the stability of DS-TCHNN in asynchronous update mode and synchronous update mode. Simulation results show that TCHNN can skip local minima and has better anti-noise performance than HNN. While, DS-TCHNN inherits all the advantages of TCHNN and its speed of convergence is fast. Besides, DS-TCHNN needs shorter data to reach a global true equilibrium point so that the computational complexity is reduced and the running time is shortened.
Coupled-cluster single-double theory study on the analytic potential energy function of the SeN2 radicals
Authors: Zeng Hui  , Zhao Jun  ,   School of Physical Science and Technology, Yangtze University, Jingzhou 434023, China
Published: December 2020

The coupled-cluster single-double (CCSD) theory in combination with the quadruple correlation-consistent basis set (cc-pVQZ) of Dunning and co-workers is employed to estimate the equilibrium geometry, dissociation energy and vibrational frequencies of the SeN2 radical. The computational results show that the ground state of SeN2 has C2v symmetry and its ground electronic state is X1A1. The equilibrium parameters of the structure are RSe-N=0.1691 nm, RN-N=0.1970 nm, αN-Se-N =71.289°, and the dissociation energy is De=4.78 eV. The vibrational frequencies are ν1=326.9288 cm-1, ν2=808.0161 cm-1, and ν3=948.3430 cm-1, respectively. The whole potential curves for the ground electronic states of SeN and N2 are further scanned using the above method, the potential energy functions and relevant spectroscopic constants are then obtained by least square fitting to the Murrell-Sorbie function. Compared with other theoretical results and the experimental values, our computational results are very accurate. Then the analytic potential energy function of SeN2 is derived by many-body expansion theory. The potential curves correctly describe the configurations and the dissociation energy for the SeN2 radical.
Laser-micro-engraving method to modify frequency difference of two-frequency HeNe lasers
Authors: Zhu Shou-Shen  , Zhang Shu-Lian  , Liu Wei-Xin  , Niu Hai-Sha  ,   State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instruments, Tsinghua University, Beijing 100084, China
Published: December 2020

In the field of precision measurement, HeNe laser is the first choice for fabricating laser interferometer. But the frequency difference of Birefringence-Zeeman dual-frequency HeNe laser, which can produce a medium frequency difference of 440 MHz, is randomly from as small as hundreds of kHz to as large as a dozen of MHz. To meet the production requirements for frequency difference of dual-frequency laser interferometer, there are some methods such as elastic strength and hole-drilling stress adjustment. But in the practical application, these methods are not very satisfactory. Laser-micro-engraving method assigns frequency difference by engraving a pattern in the plane mirror, and causes the phase retardation to achieve the purpose of frequency difference assignment. Laser engraving technique has many advantages: harmless to the laser, beauty, low power loss. The output power is close to the original light intensity. The frequency difference can be repeatedly adjusted and is stable. By frequency stabilization, the frequency difference fluctuates in a range of less than 10 kHz per hour.
Influence of NiOx hole-transporting layer on the light absorption of the polymer solar cells
Authors: Pu Nian-Nian  , Li Hai-Rong  , Xie Long-Zhen  ,   Institute of Micro-Electronics, Lanzhou University, Lanzhou 730001, China;,   Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou 730001, China
Published: December 2020

Polymer solar cell composed of the blend bulk- heterojunctions is fabricated by the conjugated polymer as donor material and fullerene as acceptor material. P3HT and PCBM are chosen in the present study. The effect of the NiOx layer on the light absorption of the polymer solar cell is investigated via the transfer matrix of the multilayer dielectric film, Maxwell equations and photon absorption equation. NiOx as alternative material of PEDOT:PSS in polymer solar cell can redistribute the electromagetic field of device and effectively improve the light absortption. in the device with structure of ITO/HTL/P3HT:PCBM/LiF:Al, and the effects of PEDOT:PSS and the NiOx on the performance of device are investigated by numerical simulation. The results show that the optimal NiOx layer device with a thickness of 10 nm has a larger short-circuit current, filling factor and energy-conversion efficiency than the 40 mm thick PEDOT:PSS device.
Effects of Cu elements on Cu(In,Ga)Se2 film and solar cell
Authors: Liu Fang-Fang  , He Qing  , Zhou Zhi-Qiang  , Sun Yun  ,   Key Laboratory of Photoelectronic Thin Film Devices and Technique of Tianjin, Nankai University, Tianjin 300071, China
Published: December 2020

The Cu elements of Cu (In, Ga) Se2 (CIGS) have very important influences on the electrical properties of CIGS absorber and solar cells. In this paper, Cu-poor and Cu-rich absorber layers (0.7 Cu/(Ga+In) (1.15) and solar cells are prepared by evaporation method. The SEM and Hall measurements reveal that Cu-rich material shows superior structural (larger grain size, better crystalline) and electrical (lower resistivity, higher mobility) properties to Cu-poor material. However, I-V tests show that the efficiency of Cu-poor solar cell is better than that of the Cu-rich device. The temperature-dependent I-V tests indicate that electron loss is mainly due to the bulk recombination in Cu-poor solar cell, and the activation energy of recombination is comparable to the band gap energy of Cu-poor solar cell. In contrast, in the Cu-rich devices the recombination at the heterointerface is dominant, and the activation energy is smaller than the band gap energy of the absorber material, which is an important drawback of open circuit voltage. Finally, Cu-poor surface on Cu-rich absorber is prepared by three-stage evaporation process, which reduces the short-circuit current and open-circuit voltage loss and optimizes the performance of CIGS solar cells. The efficiency of CIGS solar cell is achieved to be as high as more than 15%.
Effects of La, Ce and Nd doping on the electronic structure of monolayer MoS2
Authors: Lei Tian-Min  , Wu Sheng-Bao  , Zhang Yu-Ming  , Guo Hui  , Chen De-Lin  , Zhang Zhi-Yong  ,   School of Advanced Materials and Nanotechnology, Xidian University, Xi’an 710071, China;,   School of Microelectronics, Xidian University, Xi’an 710071, China;,   School of Information Technology, Northwest University, Xi’an 710069, China
Published: December 2020

To study the effect of rare earth element doping on the electronic structure of monolayer MoS2, the lattice parameters, band structures, density of states, and electron density differences of La, Ce and Nd doped and intrinsic monolayer MoS2 are calculated, respectively, using first-principles density functional theory based on the plane wave pseudopotential method in this paper. Calculations indicate that variations of bond length near La impurity are maximum, but they are the minimum near Nd impurity. Analysis points out that lattice distortion in doped monolayer of MoS2 is relative to the magnitude of the covalent radius of doping atom. Analysis of band structure shows that La, Ce and Nd doping can induce three, six and four energy levels, respectively, in the forbidden band of MoS2, and that the properties of impurity levels are analyzed. Rare earth doped monolayer MoS2 make change in electron distribution through the analysis of electron density difference, and especially, the existence of f electrons can induce the electron density difference to exhibit a physical image with a great contrast.
Grain refinement influence on the critical current density of the MgB2 superconductor sample
Authors: Guo Zhi-Chao  , Li Ping-Lin  ,   International Laboratory of Quantum Functional Material of Henan Province, School of Physics and Engineering, Zhengzhou University, Zhengzhou 450001, China
Published: December 2020

There exist two kinds of critical current densities in polycrystalline bulk of MgB2, i.e., the large local critical current density corresponding to the shielding current in inductive measurements, which flows inside the grains, and the small global critical current density that flows through the grains for whole sample. This behavior is considered to be mainly caused by the significant granularity in polycrystalline bulk. In this work, MgB2 superconductors are prepared under different Spark plasma sintering (SPS) heating rates. The microstructures of the samples are investigated, and their critical current densities are measured by Campbell method from the penetrating AC flux profile and the AC magnetic field versus penetration depth. It is found that an extremely high global critical current flows through the whole sample with a bigger grain size, which is prepared by a low heating rate during SPS sintering. That is to say, the grain refinement only increases the local critical current density of the sample. These results imply that the global current is reduced due to the existence of various defects and the poor electrical connectivity in MgB2 sample.
Enhancement of surface photoconductivityin 6H-silicon carbide crystal modified by femtosecond laser pulse irradiation
Authors: Gao Ren-Xi  , Gao Sheng-Ying  , Fan Guang-Hua  , Liu Jie  , Wang Qiang  , Zhao Hai-Feng  , Qu Shi-Liang  ,   Department of Optoelectronic Science School of Science, Harbin Institute of Technology at Weihai, Weihai 264209, China;,   Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China
Published: December 2020

The photocurrent is very small when the visible light irradiates the semi-insulating silicon carbide. The femtosecond laser pulses are used to modify the silicon carbide surface, and the result shows that the photocurrent is enlarged several times according to the measurement results of photoconductivity. In order to explain the reasons for this change, some characterization means are employed, including the absorption, emission and X-ray photoelectron spectra. There are found some changes in the absorption spectra and emission spectra, and also in the silicon and carbon atom ratio according to the test results of X-ray photoelectron spectrum. We think that the changes of the crystal structure and atom ratio between silicon and carbon lead to the change of electronic energy band structure and the occurrence of many defect states. As a result, the photocurrents are improved in the range of visible light on the surface of 6H-SiC after the femtosecond laser pulses have irradiated the surface.
Research progress of substrate materials used for GaN-Based light emitting diodes
Authors: Chen Wei-Chao  , Tang Hui-Li  , Luo Ping  , Ma Wei-Wei  , Xu Xiao-Dong  , Qian Xiao-Bo  , Jiang Da-Peng  , Wu Feng  , Wang Jing-Ya  , Xu Jun  ,   Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 201800, China;,   University of Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

GaN-based light emitting diodes (LEDs) as the third generation of lighting devices, have been rapidly developed in recent years. Substrate materials, serving as the LED manufacturing basis, have great influences on the production and application of LED. The critical characteristics of substrate affecting the design and fabrication of LED are its crystal structure, thermal expansion coefficient, thermal conductivity, optical transmittance, and electrical conductivity. In this paper, we compare several common substrate materials, namely, sapphire, silicon carbide, silicon, gallium nitride and gallium oxide, review the research progress of the substrate materials in the aspects of high quality epitaxial growths, high performance device designs and preparations of substrates, and comment on their further development.
Characteristic scale selection of lamellar spacings in binary eutectic solidification
Authors: Meng Guang-Hui  , Lin Xin  ,   Department of Mechanical Engineering, Xi’an Aeronautical University, Xi’an 710077, China;,   State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072, China
Published: December 2020

The lamellar spacing, which is formed by solidified melt of eutectic or near-eutectic composition, plays a very important role in determining the properties of final products. In this study, the lamellar spacing of eutectic growth in steady-state is predicted by the method which is established based on the classical Jackson-Hunt theory, and completed by considering the free energy change during eutectic solidification at small undercooling. The density difference between the solid phases is also considered when calculating the diffusion field in the liquid. It is found that a band of lamellar spacings would be generally selected for a given alloy under fixed growth conditions. In addition, the lamellar spacing can be morphologically stable below the minimum undercooling value, and this overstabilization is only dependent on the intrinsic characteristic properties of a given system at a fixed growth velocity. The analysis results are found to be in reasonable agreement with experimental data of Al-Al2Cu, Sn-Pb and CBr4-C2Cl6 systems available from the literature.
On-line identification for low frequency oscillation based on CCF-TLS-ESPRIT algorithm
Authors: Hu Nan  , Li Xing-Yuan  , Li Kuan  , Qin Bo  ,   School of Electrical Engineering and Information, Sichuan University, Chengdu 610065, China
Published: December 2020

On-line identification for low frequency oscillation needs to measure signals which couple with white Gaussian noise from wide area monitoring systems (WAMSs). Processed by low pass filter, white Gaussian noise can turn into colored Gaussian noise, so the accuracy of oscillatory indentification would be reduced. To solve the problem of colored Gaussian noise, in this paper we propose a cross-correlation-function (CCF) method that could reduce the influence of colored Gaussian noise. Combined with TLS-ESPRIT algorithm, CCF-TLS-ESPRIT could identify oscillatory modes in the environment of colored Gaussian noise rapidly. The simulation results show the effectiveness of the proposed method.
Study on force sencitivity of electronic transport properties of 1,4-butanedithiol molecular device
Authors: Liu Ran  , Bao De-Liang  , Jiao Yang  , Wan Ling-Wen  , Li Zong-Liang  , Wang Chuan-Kui  ,   College of Physics and Electronics, Shandong Normal University, Jinan 250014, China
Published: December 2020

Based on the hybrid density functional theory, the relationship between geometric structure of 1,4-butanedithiol molecular junction and the electrodes force and the breaking process of the molecular junction are studied. The electronic transport properties of the molecular junction under different external forces are further investigated using the elastic scattering Green’s function method. The numerical results show that different interface configurations result in different rupture forces. The rupture force is about 1.75 nN when the terminal S atom is sited at the hollow position of Au(111) surface. However, the rupture force is about 1.0 nN when the terminal S atom links with one Au atom which is on the gold surface singly. And with the breakdown of the molecular junction, the single Au atom is pulled away from the gold surface by the terminal S atom. These two results are consistent with different experimental measurements respectively. The molecule is twisted under the electrode pressure and thus further induces the surface Au atom to glide on the gold surface. However, the processes of the molecule twisted by pressure and restored by pulling are two irreversible processes. The stretching force of electrode is 0.7–0.8 nN, and the conductance always shows a minimal value under different interface configurations and twisting states, which is consistent with experimental conclusion. The change of the coupling between the terminal atom and the electrodes induced by the electrode force is the main factor of influencing the conductance of the molecular system. The existence of bimolecular junction results in a small possibility of higher conductance values, which is probed by experiment under a stretching force of about 0.8 nN.
Independent function element：model, method and application
Authors: Ma Yong  , Cheng Xie-Feng  ,   School of Computer Science, Nanjing University of Science and Technology, Nanjing 210094, China;,   College of Electronic Science and Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210003, China
Published: December 2020

In the paper, we present a new method for signal processing in statistical domain. The multiple components obtained from the conventional linear transformation are possibly irrelevant, and usually do not possess the characteristics of statistical independence. Therefore a method of signal decomposition and reconstruction is proposed based on the independent function element. This method not only inherits the advantages of linear transformation, but also has the capability of signal representation in the statistical domain. In this paper, the model, definition and obtaining method of independent function element are discussed, and the applications of heart sounds independent function element in the heart sound signal processing are also analyzed in detail. The validity and practicability of the method are demonstrated through two experiments.
A new car-following model considering drivers heterogeneity of the disturbance risk appetite
Authors: Zeng You-Zhi  , Zhang Ning  , Liu Li-Juan  ,   School of Economics and Management, Beijing University of Aeronautics and Astronautics, Beijing 100083, China
Published: December 2020

Based on the optimal velocity model, with the consideration of the effect of drivers heterogeneity of the disturbance risk appetite, an extended model is proposed. The linear stable judging condition is obtained for the extended model by its stability analysis, which shows the smaller the ratio of the coefficient of the disturbance risk appetite for the former car driver to that for the following-car driver, the larger the stability area of the extended model is. The kink-antikink density wave is attained in an unstable area of the model by nonlinear analysis. Simulation results also show that the smaller the ratio of the coefficient of the disturbance risk appetite for the former car driver to that for the following-car driver, the better it is for the initial traffic flow to inhibit the disturbance propagation, hinder the formation of traffic jams and restore homeostasis. This paper provides a viable idea to reduce traffic congestion, for example, by forming convoys traveling in order from small to big according to the relative size of drivers coefficients of the disturbance risk appetite.
Geostrophic momentum approximation Q-vector and its application in synoptic charts
Authors: Zhou Xiao-Gang  , Zhu He  , Wang Xiu-Ming  ,   China Meteorological Administration Training Center, Beijing 100081, China
Published: December 2020

In this paper, we extend the expression of quasi-geostrophic Q-vector brought forward by Hoskins et al. into the Q-vector equation under the condition of geostrophic momentum approximation, and discuss the method of how to quantitatively estimate vertical motion in synoptic charts with Q-vector expression under geostrophic momentum approximation. Compared with the expression of quasi-geostrophic Q-vector, the Q-vector expression under geostrophic momentum approximation has two more terms which are related to geopotential height extremum and wind velocity extremum. Then, each term of Q-vector under geostrophic momentum approximation is transformed into the expression which is conveniently judged in synoptic charts. The results show that to judge vertical motions in synoptic chart quantitatively, one of the three ways can be used: when contour line presents the form of wave-like trough-ridge and passes through the entrance and exit areas of jet stream, correspondingly use the 1st term of Q-vector under geostrophic momentum approximation (i.e., quasi-geostrophic Q-vector); when there exist a closed pressure system and an angle between contour line and wind velocity, correspondingly use the 2nd term of Q-vector under geostrophic momentum approximation; at the jet streak, correspondingly use the 3rd term of Q-vector under geostrophic momentum approximation.
Analysis of data obtained by the solar wind ion detector onboard the Chang’E-1 Lunar orbiter
Authors: Shi Hong  , Tian Li-Cheng  , Yang Sheng-Sheng  ,   Science and Technology on Vacuum and Cryogenics Technology and Physics Laboratory, Lanzhou Institute of Physics, Lanzhou 730000, China
Published: December 2020

The interaction between lunar plasma and spacecraft may cause surface charging/discharging effects, and degrade the performance of spacecraft. The charging potential is a key factor for discharging process. In order to evaluate charging/discharging effects, it is necessary to obtain the Lunar plasma environment. SWIDA/B on Chang’E-1 are the two scientific instruments of solar wind ion detector which could explore the plasma environment in the 200 km Lunar orbit, thereby deducing the solar wind bulk speed, density and temperature. In this paper we select the data in June 2008 derived from SWIDA sensor. First, we figure out the solar wind ion differential flux and energy spectrum, and then calculate the solar wind parameters such as velocity (300.00–600.00 km/s), plasma density (1–10 cm-3) and plasma temperature (1–20 eV). Finally, we adopt an equivalent circuit model to compute the Lunar spacecraft surface charging voltage which is -7–-70 V.
Simulation of optimal control of train movement based on car-following model
Authors: Ye Jing-Jing  , Li Ke-Ping  , Jin Xin-Min  ,   School of Electrical Engineering, Beijing Jiaotong University, Beijing 100044, China;,   State Key Laboratory of Rail Traffic Control and Safety, Beijing Jiaotong University, Beijing 100044, China;,   Beijing Laboratory of Urban Rail Transit, Beijing Jiaotong University, Beijing 100044, China
Published: December 2020

Optimal control of train movement is an important way to reduce transport cost, enhance service level, and realize sustainable development. In this paper, based on traditional optimal velocity car-following model, an improved simulation model is presented, it is used to optimize the velocity control of train movement in urban railway system. The proposed model is established by introducing a new function of objective optimal velocity into the classical optimal velocity model (See Phys. Rev. E 51, 1035, Bando et al, 1995) to realize the optimal control of train movement in complicated conditions. Numerical simulation takes the Beijing City Metro Yi Zhuang line as an example. Here some reality measurement data is used. Results show that the proposed model can well describe the dynamic characteristics of train movement under the complex limited condition. Simulation results are close to reality measurement data. This demonstrates that the proposed model is valid. Further, by analyzing the space-time graph, the change of train velocity and travel time, the evolution characters of train flow under complex conditions are discussed.
Modeling and simulation analysis of fractional-order Boost converter in pseudo-continuous conduction mode
Authors: Tan Cheng  , Liang Zhi-Shan  ,   College of Geophysics and Information Engineering, China University of Petroleum (Beijing), Beijing 102249, China
Published: December 2020

Based on the fact that the inductor and the capacitor are fractional in nature, the fractional order mathematical model of the Boost converter in pseudo-continuous conduction mode is established by using fractional order calculus theory. According to the state average modeling method, the fractional order state average model of Boost converter in pseudo-continuous conduction mode is built. In view of the mathematical model, the inductor current and the output voltage are analyzed and the transfer functions are derived. Then the differences between the integer order and the fractional order mathematical models are analyzed. On the basis of the improved Oustaloup fractional order calculus for filter approximation algorithm and the model of fractional order inductance and capacitance, the simulation results have been compared between the mathematical model and circuit model with Matlab/Simulink software; the origins of model error are analyzed and the correctness of the modeling in fractional order and the theoretical analysis is verified. Finally, the differences and the relations of Boost converter among the continuous conduction mode, the discontinuous conduction mode, and the pseudo-continuous conduction mode are indicated.
Manipulation of the complete chaos synchronization in dual-channel encryption system based on polarization-division-multiplexing
Authors: Zhong Dong-Zhou  , Deng Tao  , Zheng Guo-Liang  ,   School of Information Engineering, Wuyi University, Jiangmen 529020, China;,   School of Physics, Southwest University, Chongqing 400715, China;,   College of Electronic Science and Technology, Shenzhen University, Shenzhen 518060, China
Published: December 2020

For the dual-channel encryption system, based on polarization-division-multiplexing, we put forward a new control scheme for complete chaos synchronization by means of linear electro-optic (EO) effect. In the scheme, the chaotic synchronization quality of each linear polarization (LP) mode component varies periodically with the applied electric field. The variation regulation is as follows: Complete chaos synchronization ↔ acute oscillation. With the applied electric field fixed at a certain value, the robustness of the complete chaotic synchronization quality due to the bias current and the feedback strength is improved greatly by EO modulation. Each LP mode can obtain the complete chaos synchronization in a large range of the bias current and the feedback strength. And the encoding message modulated to each LP mode can be almost re-established.
Theoretical and experimental study on the multi-color broadband coherent anti-Stokes Raman scattering processes
Authors: Yin Jun  , Yu Feng  , Hou Guo-Hui  , Liang Run-Fu  , Tian Yu-Liang  , Lin Zi-Yang  , Niu Han-Ben  ,   College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China,   Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, Shenzhen University, Shenzhen 518060, China
Published: December 2020

In order to exactly distinguish and quantitatively analyze the different or unknown components in a mixture, the global molecular CARS spectra information should be obtained simultaneously with a broad-band coherent anti-Stokes Raman scattering (CARS) spectroscopy in supercontinuum. In a broad-band CARS spectroscopy, two-and three-color CARS processes are generated due to different functions of effective spectroscopic components in supercontinuum. Firstly, we theoretically analyzed the generation conditions of CARS signals and the relationships between their intensity and power of excitation lights in the two types of CARS process with the broad-band excitation. On this basis, the two types of CARS process are achieved with a home-built broad-band CARS spectroscopic system, respectively. Using the functional fitting analysis of the obtained CARS spectral signals of benzonitrile, the relationships between CARS signals and excitation lights are experimentally verified in two different kinds of CARS process. Further optimizations of broad-band time-resolved CARS spectroscopic and microscopic systems, for simultaneously obtaining the global CARS spectral signals of samples, can be achieved under the guidance of theoretical and experimental results.
Ab initio calculation of the potential energy curves and spectroscopic properties of BP molecule
Authors: Wang Wen-Bao  , Yu Kun  , Zhang Xiao-Mei  , Liu Yu-Fang  ,   College of Physics & Electronic Engineering, Henan Normal University, Xinxiang 453007, China;,   College of Physics & Engineering, Xingyi Normal University for Nationalities, Xingyi 562400, China
Published: December 2020

A high-precision quantum chemistry ab initio multi-reference configuration interaction method with aug-cc-pVQZ basis sets has been used to calculate the four states of BP molecule. The four -S states are X3, 3-, 5 and 5-, which are correlated to the lowest dissociation limit of B(2Pu)+P(4Su). Analysis of the electronic structures of -S states shows that the -S electronic states are essentially multi-configurational. We take the spin-orbit interaction into account for the first time so far as we know, which makes the four -S states split into fifteen states. 30+ state is confirmed to be the ground state. The SOC effect is essential for the BP molecule, which leads to the avoided crossings for 0+ and 1 states from X3 and 3-. Based on the PECs of -S and states, the accurate spectroscopic constants are obtained by solving the radial Schrdinger equation. The spectroscopic results may be conducive to further research on BP molecule in experiment and theory.
Theoretical analysis on cavity-enhanced laser cooling of Er3+-doped glasses
Authors: Jia You-Hua  , Gao Yong  , Zhong Biao  , Yin Jian-Ping  ,   Science college, Shanghai Second Polytechnic University, Shanghai 201209, China;,   State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, China
Published: December 2020

In recent years, Er3+ doped CdF2-CdCl2-NaF-BaF2-BaCl2-ZnF2 (CNBZN) glass has become one of the new materials in the field of laser cooling of solids. In this paper, using the theory of laser output and standing wave resonance, intracavity-and extracavity-enhanced laser cooling of Er3+-doped CNBZN glass are theoretically analyzed. Calculated results show that enhancement factor can achieve tens to hundreds of times. Moreover, two schemes are compared with each other, and the results show that for low material absorption, especially when the sample length is less than 0.3 mm, intracavity configuration has the advantage of high pumping power and high absorption. However, for high material absorption, especially when the sample length is longer than 3 mm, the extracavity configuration becomes a more efficient means for laser cooling. Finally, according to the operating wavelength and power requirements of Er3+-doped material, cavity enhancement can be realized experimentally using semiconductor diode laser.
Statistical analysis of shot-to-shot variation of laser fluence spatial distribution
Authors: Han Wei  , Zhou Li-Dan  , Li Fu-Quan  , Wang Fang  , Feng Bin  , Zheng Kui-Xin  , Gong Ma-Li  ,   Department of Precision Instruments and Mechanology, Tsinghua University, Beijing 100084, China;,   Research Center of Laser Fusion, CAEP, P.O.Box 919-988, Mianyang 621900, China
Published: December 2020

The shot-to-shot variation of laser fluence spatial distribution on a large-aperture high-power laser facility is statistically analyzed. Statistical results show that the maximum fluence spatial distribution to which any location in the optic beam will be exposed after N shots, can be described by Gaussian function, and the average fluence across the beam increases with laser shots while standard deviation is relatively constant, independent of laser shots. This is due to the fact that laser fluence spatial distribution possesses similarity over the whole beam and dissimilarity at local positions for different laser shots.
Study on the fabrication of gold electrode by laser assembling
Authors: Zhang Ran  , Lü Chao  , Xiao Xin-Ze  , Luo Yang  , He Yan  , Xu Ying  ,   State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012, China;,   Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China
Published: December 2020

We proposed the fabrication of gold micro-electrode and grating electrode through laser assembling of gold nanoparticles and realized the electrical interconnection of the single carbon nanotube and gold nanolines, which can decrease the damage of the functional unit to a great extent. This method can also solve the problem of inadequate mass transport in the fabrication of ions. The microstructure could keep unoxidized in the atomasphere with excellent continuity, integrity, and electrical properties, which made this technique have wide application prospects.
Crystals modulated by two parameters and their applications
Authors: Li Chang-Sheng  ,   Department of Optoelectronics Engineering, School of Instrumentation Science and Optoelectronics Engineering, Beihang University, Beijing 100191, China
Published: December 2020

In the applications of two external fields, such as stresses and electric fields, the optical modulation properties of some crystals are theoretically analyzed using the method of index ellipsoid. Simple mathematical formulas for the calculations of the field-induced principal refractive indexes of some crystals and corresponding azimuthal angles of their principal axes can be deduced from the equation of index ellipsoid if there exists only one nonzero cross term in the equation, e.g. x1x2. According to these simple formulas, we can find out some crystals exhibiting dual transverse electrooptic effect, e.g. crystals of the 6 symmetry point group. Under two simultaneously applied external stresses, elastooptic birefringence of a crystal is proportional to the difference between the two external stresses, and the orientations of their birefringent axes are unchanged. When a stress and an electric field are simultaneously and perpendicularly applied to some crystals such as cubic crystals of 43m point group, the field-induced birefringence of the crystal is proportional to the weighted geometric mean of the applied stress and electric field, and the orientations of their birefringent axes only depend on the ratio of the applied electric field and stress. The above electrooptic and elastooptic modulation properties are useful to the design of novel optical modulators and sensors.
Analysis of electron momentum relaxation time in fused silica using a tightly focused femtosecond laser pulse
Authors: Bian Hua-Dong  , Dai Ye  , Ye Jun-Yi  , Song Juan  , Yan Xiao-Na  , Ma Guo-Hong  ,   Department of Physics, Shanghai University, Shanghai 200444, China;,   School of Material Science and Engineering, Jiangsu University, Zhenjiang 212013, China
Published: December 2020

The electron momentum relaxation time is studied systematically in order to understand its effect during the excited nonlinear ionization process in fused silica with an irradiation of tightly focused femtosecond laser pulses. According to the analysis of a (3+1)-dimensional extended general nonlinear Schrödinger equation, the electron momentum relaxation time shows a huge effect on peak intensity, free electron density, and fluence distributions in the focal region of the incident pulse, meanwhile a value of 1.27 fs is thought to meet the present experimental result based on the theoretical model. Further research indicates that the change of electron momentum relaxation time can have significant difference among several nonlinear mechanisms, such as the laser-induced avalanche ionization, reverse bremsstrahlung, self-defocusing of plasma, etc. Results show that the electron momentum relaxation time plays an important role in the process of femtosecond laser pulses interaction with materials.
Study of 1550 nm low loss single mode all-solid photonic bandgap fibers
Authors: Cheng Lan  , Luo Xing  , Wei Hui-Feng  , Li Hai-Qing  , Peng Jing-Gang  , Dai Neng-Li  , Li Jin-Yan  ,   Wuhan National Laboratory for Optoelectronics, Wuhan 430074, China
Published: December 2020

All-solid photonic bandgap fiber shave attracted great attention of researchers due to their particular band gap and dispersion character as well as the merit of easily splicing the traditional optical fiber. We have fabricated the all-solid photonic bandgap fibers using the plasma chemical vapor deposition (PCVD) and a modified tack and draw technique, and the loss and dispersion characteristics were simulated by the finite-difference frequency-domain (FDFD) method. The fiber obtained by this method has a low-loss region at around 1550 nm and can be used as single-mode; its effective model field area and the dispersion of the fiber at 1550 nm are 191.81 μm2 and 16.418 ps/(km·nm), respectively. Combined with the experimental results, the fiber parameters are further optimized by simulation.
Molecular dynamics simulation of the thermal conductivity of silicon functionalized graphene
Authors: Hui Zhi-Xin  , He Peng-Fei  , Dai Ying  , Wu Ai-Hui  ,   School of Aerospace Engineering and Applied Mechanics, Tongji University, Shanghai 200091, China;,   School of Physics and Information Technology, Ningxia Normal College, Guyuan 756000, China
Published: December 2020

Direct non-equilibrium molecular dynamics (NEMD) was used to simulate the thermal conductivities of the monolayer and the bilayer silicon functionalized graphenes along the length direction respectively, with the Tersoff potential and the Lennard-Jones potential, based on the velocity Verlet time stepping algorithm and the Fourier law. Simulation results indicate that the thermal conductivity of the monolayer silicon functionalized graphene decreases rapidly with increasing amount of silicon atoms. This phenomenon could be primarily attributed to the changes of graphene phonon modes, mean free path, and motion speed after silicon atoms are embedded in the graphene layer. Meanwhile, the thermal conductivity of the monolayer graphene is declined in the temperature range from 300 to 1000 K. As for the bilayer silicon functionalized graphene, its thermal conductivity increases as a few silicon atoms are inserted into the layer, but decreases when the number of silicon atoms reaches a certain value.
Fractional derivative dynamics of intermittent turbulence
Authors: Liu Shi-Da  , Fu Zun-Tao  , Liu Shi-Kuo  ,   Department of Atmospheric and Oceanic Sciences and Laboratory for Climate and Ocean-Atmosphere Studies, School of Physics, Peking University, Beijing 100871, China
Published: December 2020

Intermittent turbulence means that the turbulence eddies do not fill the space completely, so the dimension of an intermittent turbulence takes the values between 2 and 3. Turbulence diffusion is a super-diffusion, and the probability of density function is fat-tailed. In this paper, the viscosity term in the Navier-Stokes equation will be denoted as a fractional derivative of Laplatian operator. Dimensionless analysis shows that the order of the fractional derivative α is closely related to the dimension of intermittent turbulence D. For the homogeneous isotropic Kolmogorov turbulence, the order of the fractional derivatives α=2, i.e. the turbulence can be modeled by the integer order of Navier-Stokes equation. However, the intermittent turbulence must be modeled by the fractional derivative of Navier-Stokes equation. For the Kolmogorov turbulence, diffusion displacement is proportional to t3, i.e. Richardson diffusion, but for the intermittent turbulence, diffusion displacement is stronger than Richardson diffusion.
A novel lattice Boltzmann method for dealing with arbitrarily complex fluid-solid boundaries
Authors: Shi Dong-Yan  , Wang Zhi-Kai  , Zhang A-Man  ,   College of Mechanical and Electrical Engineering, Harbin Engineering University, Harbin 150001, China;,   College of Shipbuilding Engineering, Harbin Engineering University, Harbin 150001, China
Published: December 2020

A suitable arbitrarily complex boundary condition treatment using the lattice Boltzmann sheme is developed in the fluid-solid coupling field. The new method is based on a half-way bounce back model. A virtual boundary layer is built with the fluid-solid coupling, and all the properties used on the virtual boundary are inter-/extrapolated from the surrounding nodes combining with the finite difference method. The improved method ensures that the particles bounce the same location as that of the macro-speed sampling point, and considers the offset effect on the accuracy of the calculated results when the actual physical borders and the grid lines do not coincide. And its scope is extended to any static or mobile, straight or curved boundary. The processing power of the method under the classic conditions, such as the Poiseuille flow, the flow around a circular cylinder, the Couette flow, etc. is studied. Results prove that the theoretically calculated values agree well with the experimental data. Compared with the results published in the literature, this method has a greater precision when the actual physical borders and gridlines do not coincide.