bluuebunny/crossref_metadata_2025 huggingface dataset:
The structure and analytical potential energy function of the ground state of HNO molecule
Authors: Zhao Jun  , Zeng Hui  , Zhu Zheng-He  ,   School of Physical Science and Technology, Yangtze University, Jingzhou 434023, China;,   Institute of Atomic and Molecular Physics , Sichuan University, Chengdu 610065, China
Published: December 2020

The ground electronic state and the reasonable dissociation limit of HNO molecule are determined based on the group theory and the atomic and molecular reaction statics. The energy, the equilibrium geometry and the harmonic frequency of the ground electronic state of HNO are calculated using the density functional theory B3LYP method in combination with the 6-311G ** basis set. The computational results show that the ground state of HNO molecule has CS symmetry, its ground electronic state is X1A', and the equilibrium parameters of the structure are RHN=0.1065nm, RNO=0.1200 nm,HNO=108.60, dissociation energy De=15.379 eV, bending vibrational frequency 1=1575.6351 cm-1, symmetric stretch frequency 2=1673.2890 cm-1, and asymmetric stretch frequency 3=2837.7856 cm-1. Then the analytic potential energy function of HNO molecule is derived by the many-body expansion theory. The potential curves correctly describe the configurations and the dissociation energy for the HNO molecule.
Control of atomic path in projectile cold atom gyroscope
Authors: Xiong Zong-Yuan  , Yao Zhan-Wei  , Wang Ling  , Li Run-Bin  , Wang Jin  , Zhan Ming-Sheng  ,   State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan National Laboratory for Optoelectronics, Wuhan 430071, China;,   Center for Cold Atom Physics, Chinese Academy of Sciences, Wuhan 430071, China;,   Graduate University,Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

Cold atoms possess low velocity, narrow velocity distribution as well as good matter wave coherence, thus they have been used to achieve cold atom interferometers. The interferometers with Sagnac effect form atom gyroscopes which can measure rotation rate accurately. Here we report our recent progress in building a projectile cold atom gyroscope. We achieve the accurate control of the bidirectional projectile cold atom motion through the use of a homemade direct digital frequency synthesizer.
Analysis of momentum and energy resolutions of the reaction microscope
Authors: Guo Da-Long  , Ma Xin-Wen  , Feng Wen-Tian  , Zhang Shao-Feng  , Zhu Xiao-Long  ,   (1)Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China; (2)Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China;Graduate University of Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

Based on the working principle of the reaction microscope and the technical parameters employed in our setup, all the possible factors which affect the momentum resolutions of the recoil-ions and the electrons are analyzed. The resolution dependences on the parameters are discussed in detail. The target extension is critical to the momentum and energy resolutions. For electrons the energy resolution is sensitive to the momentum anti-parallel to the extraction electric field: the larger the momentum, the worse the resolution is. The results are applicable to both longitudinal and transverse reaction microscopes.
Simulations of one-dimensional transverse laser cooling of Cr atomic beam with Monte Carlo method
Authors: Zhang Bao-Wu  , Zhang Ping-Ping  , Ma Yan  , Li Tong-Bao  ,   China Jiliang University, Zhejiang 310018, China;,   State Key Laboratory of Precision Measurement Technology and Instruments,Tsinghua University 100084, China;,   Tongji University, Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology, Shanghai 200092, China
Published: December 2020

A well collimated atomic beam plays an important role in laser focused Cr atom deposition. The simulations of one-dimensional (1D) transverse laser cooling of Cr atomic beam is performed with the Monte Carlo method. Taking into account the stochastic initial conditions of each atom, isotopes other than 52Cr, longitudinal velocity distribution and transverse divergence, the atomic beam cooled by laser is optimized and evaluated. The obtained results are consistent with experimental. In addition, with picking out the trajectories of isotopes other than 52Cr that are not cooled by the laser the center maximum value can be reduced by 9.3%, and the FWHM is increased by 11% of the transverse distribution.
Design and study of miniaturized-element frequency selective surfaces
Authors: Xu Nian-Xi  , Feng Xiao-Guo  , Wang Yan-Song  , Chen Xin  , Gao Jin-Song  ,   Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China;,   Graduate School of the Chinese Academy of Sciences, Beijing 100039, China
Published: December 2020

We propose a miniaturized-element frequency selective surface (MEFSS) by using the coupling mechanisms between capacitive surface and inductive surface, so the uint cell size will not be restricted by wavelength. In order to improve resonance stability performance with respect to different polarizations and incidence angles, according to the traditional FSS Y element, we create periodic elements of capacitive surface and inductive surface with Y shape and Y element array is in the form of equilateral triangle, The grid array and the effects of the parameteristics of Y loop element on the frequency response characteristics of MEFSS are calculated using the modal matching method. With filming technology and lithography, the corresponding capacitive surface and inductive surface between polyimide are produced and a prototype MEFFSS using freedom space method is examined. Both simulated and measured results obtained show that the MEFFSS constructed by using equilateral triangle Y element array has much better f0 resonance stability performance with respect to different polarizations and 60 incidence angles, and the -3 dB bandwidth reaches up to 7.6 GHz. We present a theoretical and experimental reference of MEFSS for the applications in large-angle incidence curved streamlined radome.
Shifts of beam centroid of Laguerre-Gaussian beams reflected and refracted at a dielectric interface
Authors: Ou Jun  , Jiang Yue-Song  , Li Fang  , Liu Li  ,   School of Electronic and Information Engineering, BeiHang University, Beijing 100191, China
Published: December 2020

We study shifts of the beam centroid of linearly polarized paraxial Laguerre-Gaussian beams reflected and refracted at an interface of isotropic dielectric in the cylindrical coordinate system. According to the Fresnel approximation and the Taylor series expansion, we derive analytical expressions for transverse and longitudinal shifts and their general relationship with topological charge in the cases of partial and total reflection, respectively. It is shown that in the partial reflection regime, transverse shifts of both reflected and refracted beams are in proportion to the topological charge of beams and their directions are determined by the sign of the topological charge, while only the value of longitudinal shift is related to the topological charge. In the regime of total reflection, the shift of reflected beam centroid is independent of topological charge. To verify our analytical results, we perform numerical simulations of the shifts of reflected and refracted beams directly and indicate the applicable condition of the analytical expressions. The shifts of the beam centroid can be applied to the measurement of the topological charge and radial node number of Laguerre-Gaussian beams, which is of significance for information encoding and communication.
The delayed feedback control to suppress the vibration in a torsional vibrating system
Authors: Zhao Yan-Ying  , Li Chang-Ai  ,   School of Aircraft Engineering, Nanchang Hangkong University, Nanchang 330063, China
Published: December 2020

We investigate the delayed feedback control to suppress the vibration in a torsional vibrating system. The delayed feedback control is applied to a torsional vibrating system with a nonlinear dynamical absorber.We investigate the effects of gain and delay on vibration suppression of the primary system. The results show that for a fixed gain, the vibration of the primary system can be suppressed at some values of the delay. As the delay varies for a fixed gain, the amplitude of the primary system can be suppressed to a minimum value. The vibration of the primary system is suppressed form 0.24 to 0.03 when the gain and the delay are chosen to be appropriate values. The analytical solutions are consistent well with the numerical simulation.
Coupling characteristics research on Z-pinch driver and wire array load
Authors: Zou Wen-Kang  , Chen Lin  , Zhou Liang-Ji  , Wang Meng  , Yang Li-Bing  , Xie Wei-Ping  , Deng Jian-Jun  ,   Institute of Fluid Physics, CAEP, P.O. Box 919-108, Mianyang 621900,China
Published: December 2020

Self-consistent circuit solution of Z-pinch driver discharging and wire array implosion is realized via Pspice analog behavioral modeling (ABM) based on the 0-dimensional implosion model. The influence of wire array and circuit parameters on implosion process is investigated using the method. Results show that wire array as its load is strongly coupled with Z-pinch driver. The maximum pinch current, the implosion time and the maximum kinetic energy (Ek) transferring to wire array are very sensitive to driver and wire array parameters. When the driver doesnot change and implosion time doesnot exceed a quarter of oscillation periods, the maximum pinch current, the implosion time and the maximum Ek increase while wire array mass increasing, and implosion time decreases as initial wire array radius increases. With keeping wire array unchanged, the implosion time decreases and implosion time increases as capacitance of driver increases, but the Ek efficiency firstly increases then decreases. The optimal array parameters for a given driver should make the implosion fully use the rising edge of current pulse, and make the pinch time close to a quarter of oscillation period, so that the implosion process could obtain maximum Ek efficiency.
Effect of Co+ implantation on structural and optical properties in single-crystal TiO2
Authors: Li Tian-Jing  , Li Gong-Ping  , Ma Jun-Ping  , Gao Xing-Xin  ,   School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000, China;,   State key Laboratory of Crystal Material, Shangdong University, Jinan 250001, China
Published: December 2020

Ion implantation technique is used for doping Co+ to single crystal TiO2(001). The implanted energies and the fluences of Co+ are 40keV and 11016cm-2; 80 keV and 51015, 11016, 51016, 11017cm-2; 120 keV and 11016cm-2, respectively. And then, the structural and the optical properties of all samples are characterized by using X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD), UV - Vis diffuse reflectance spectroscopy (UV-Vis DRS), and these impurities in implanted samples are also analyzed. From the XRD spectra of implanted samples we observe that the greater damage is caused with the increase of the kinetic energy of incident ions. UV - Vis diffuse reflectance spectroscopy measurement shows that the absorbance of visible band is enhanced in all the implanted samples, and the optical band gap decreases with implanted ion fluence increasing from 51015cm-2 to 51016cm-2.
STM tip-induced atomic motion on the top of film supported by a metal substrate
Authors: Huang Ren-Zhong  , Liu Liu  , Yang Wen-Jing  ,   College of Physics Science and Technology, Shenyang Normal University, Shenyang 110034, China;,   Max-Planck-Institut für Mikrostrukturphysik,Halle D-06120, Germany
Published: December 2020

We investigate the scanning tunneling microscopy (STM) tip-modulated atomic motion on the top of Co island and interlayer mass transport on the island edge based on the molecular static (MS) method. Our results show that STM manipulation has an important effect on Co atomic diffusion on the top of Co island and on the island edge. The interaction of the STM tip with the adatom and the strong shape transitions in Co island and in the Cu(001) substrate result in the change of the jump diffusion barrier on the top of the island, the Ehrlich-Schwoebel(E-S) and exchange barrier on the island edge. It is found that by adjusting the distance between the tip and the substrate one can reduce the diffusion barrier of the above three diffusion processes and transform the growth mode of the Co films from 3D to 2D.
Formation abilities and electronic properties of Mg-TM-H (TM = Sc, Ti, V, Y, Zr, Nb) crystal
Authors: Deng Yong-He  , Liu Jing-Shuo  ,   College of Science, Hunan Institute of Engineering, Xiangtan 411104, China;,   College of Application Technical, Hunan Institute of Engineering, Xiangtan 411104, China
Published: December 2020

Theoretical studies of structures, cohesive energies,reaction enthalpies and densities of states (DOSs) of Mg7TMH16 (TM=Sc, Ti, V, Y, Zr, Nb) compounds are performed using the first-principles method based on the density functional theory in the generalized gradient approximation. The cohesive energies are calculated to analyze the stability, and the formation abilities of Mg7TiH16 and Mg7NbH16 are stronger than others. The obtained formation enthalpy for hydride Mg7TMH16 is used to investigate the possible pathways of formation reaction. The calculated formation enthalpy changes show that the decomposition temperature of Mg7TMH16 is lower than that of MgH2. The electronic DOSs reveal that all the hydrides studied here exhibit metallic characteristics.
Selective adsorption of small molecules on grafted polymers
Authors: Xu Yu-Li  , Chen Xue-Qian  , Chen Hou-Yang  , Xu Shou-Hong  , Liu Hong-Lai  ,   State Key Laboratory of Chemical Engineering and Department of Chemistry, East China University of Science and Technology, Shanghai 200237, China;,   Physics Department, East China University of Science and Technology, Shanghai 200237, China
Published: December 2020

A density functional approach to the description of the selective adsorption of a binary mixture of small molecules on a surface grafted with the square-well chains is proposed. The excess Helmholtz free energy functional of the system is divided into two contributions from the hard-sphere repulsion and the square-well attraction respectively. In the bulk phase, the equation of state of Liu and Hu (Liu H L, Hu Y 1996 Feuid Phase Equilibra 122 75) is used to calculate the free energy of the repulsive part and the equation of state of Li and He (Li J L and He H H 2009 Feuid Phase Equilibria 276 57) is used to calculate the free energy of the attractive part. A simple weighted density approximation is adopted on both parts to construct the functional. Using this theoretical approach, the structures of the grafted polymers and the selective adsorptions of binary square-well fluids on the grafted layer at different temperatures are investigated. The theory predicts that the brush thickness increases linearly with the grafting density but non-linearly with temperature and the brush thickness tends to sateration at high temperature. Given the chain length and grafting density, the theoretical calculation also reveals that the polymer brush has strong selective adsorption cap ability at low temperature and the cap ability will weaken greatly when the polymer brush is heated above the temperature of sateration.
First-principles study of influence of dopants Fe on the dehydrogenation properties of VH2
Authors: Li Rong  , Luo Xiao-Ling  , Liang Guo-Ming  , Fu Wen-Sheng  ,   Laboratory of Functional Materials, Chongqing Normal University, Chongqing 400047, China
Published: December 2020

In this paper, the influence of doping Fe on the electronic structure and the dehydrogenation property of VH2 is investigated by using the plane wave ultrasofi pseudopotential method which is base on the first principles of density functional theory (DFT). The calculated results are as follows: (1)the unit cell volume, the cell parameter, and the alloy formation heat of VH2 gradually decrease with the increase of Fe; (2) the fermi level electron density increases by dopping Fe; (3)the population the and electron density of V-H bond both decrease with doped Fe. These results indicate that the stability is declined and the interaction between V and H atom is weakened by adding Fe into the VH2 system. So it comes to the conclusion that the hydrogen desorption property of VH2 can be improved by adding Fe.
Coherent controlling surface plasmon transport properties in Ag nanowire by classic optical field
Authors: Cheng Mu-Tian  ,   School of Electrical Engineering and Information,Anhui University of Technology, Maanshan 243002, China
Published: December 2020

Coherent controlling surface plasmon transport in metal nanowire coupled to quantum dot is investigated theoretically by real-space method. In the calculations, the dispersion relation of metal nanowire is supposed to be linear and the quantum dot is a cascaded three-level system. The calculations reveal that whether the surface plasmon is transmitted or reflected by turning off or on the classic field can be controlled. The surface plasmon transmission and reflection spectra can be controlled by adjusting the intensity and the circular frequency of classic optical field even the energy of surface plasmon and quantum dot is not matched. The dissipations affecting on the transport properties are also discussed.
Theoretical research on optical properties of gain-assisted plasmonic coupled resonator optical waveguides
Authors: Shen Yun  , Fan Ding-Huan  , Fu Ji-Wu  , Yu Guo-Ping  ,   Department of Physics, Nanchang University, Nanchang 330031, China;,   Department of Physics, Wuhan University, Wuhan 430072, China
Published: December 2020

Active materials are proposed to fill into plasmonic coupled resonator optical waveguide constructed with metal rings. Optical properties including transmission, dispersion relation and group index of the waveguide are illustrated by performing the transfer matrix method analysis and the finite difference time domain simulation. The results show that the anomalous and the normal dispersions of the active material near the resonance frequency will help to flatten or slope the dispersion relation produced by the geometric structure, leading to an amplified or attenuated group index of the waveguide. Additionally, we can real-time tune the optical properties of the waveguide by electrically or optically pumping the active material. Our results verify a feasible way for the application of such a waveguide in high desity integration of optical circuits.
Transport properties of two-dimensional electron gas in lattice-matched InAlN/GaN and InAlN/AlN/GaN materials
Authors: Wang Ping-Ya  , Zhang Jin-Feng  , Xue Jun-Shuai  , Zhou Yong-Bo  , Zhang Jin-Cheng  , Hao Yue  ,   Key Laboratory of Wide Band Gap Semiconductor Materials and Devices, School of Microelectronics, Xidian University, Xi'an 710071, China
Published: December 2020

The lattice-matched InAlN/GaN structure is one kind of emerging material with high conductivity and used in GaN-based high electron mobility transistors (HEMTs). The transport properties of lattice-matched InAlN/GaN structure and InAlN/AlN/GaN structure are studied. The samples are grown using pulsed metal organic chemical vapor deposition on sapphire substates. Both structures show temperature-dependent Hall mobilities with a typical behavior of two-dimensional electron gas (2DEG). Theoretical analysis of the temperature dependence of mobility is carried out based on the comprehensive consideration of various scattering mechanisms such as acoustic deformation-potential, piezoelectric, polar optic phonon, dislocation, alloy disorder and interface roughness scattering. It is found that the dominant scattering mechanisms are the interface roughness scattering and the polar optic phonon scattering for both structures at room temperature. The insertion of AlN spacer layer into InAlN/GaN interface exempts 2DEG from alloy disorder scattering, more importantly results in a better interface, and restrains greatly interface roughness scattering. The influence of sheet density on 2DEG mobility is also considered, and the upper limit of density-dependent 2DEG mobility is given for lattice-matched InAlN/GaN and InAlN/AlN/GaN structures and compared with many reported experimental data.
Integration of SRO/PZT/SRO/Ni-Al/Cu/Ni-Al/SiO2/Si ferroelectric capacitor with copper
Authors: Chen Jian-Hui  , Liu Bao-Ting  , Zhao Qing-Xun  , Cui Yong-Liang  , Zhao Dong-Yue  , Guo Zhe  ,   College of Physics Science and Technology, Hebei University, Baoding 071002, China
Published: December 2020

To integrate ferroelectric capacitor with copper thin film, SRO/Ni-Al/Cu/Ni-Al/SiO2/Si stack is fabricated by magnetron sputtering with Ni-Al as the barriers between Cu and SiO2/Si and between Cu and SRO simultaneously in order to segregate Cu from its adjacent oxide layers for avoiding interdiffusions/reactions when samples are annealed at a high temperature. XRD and AFM are employed to study microstructure and surface morphology respectively. The Cu diffraction peaks and the uniform surfaces are found in SRO/Ni-Al/Cu/Ni-Al/SiO2/Si stack at a high temperature of 750 ℃, implying that the SRO/Ni-Al/Cu/Ni-Al/SiO2/Si stack possesses excellent stability. It is also found that growing at the lower temperature followed by annealing at a high temperature is better than current growing at the room temperature followed by annealing at a high temperature in that the former can relax stresses and reduced the roughness of interfaces to prevent the destruction of barrier and Cu layers at the high temperature. Moreover, PZT is grown on a SRO/Ni-Al/Cu/Ni-Al/SiO2/Si stack by the sol-gel method to construct a ferroelectric capacitor with copper, and the microstructure, the ferroelectric performance and leakage are investigated. The good ferroelectric properties of the capacitor with copper are presented, including a saturated hysteresis loop, remnant polarization ~42 C/cm2, coercive voltage ~1.0 V, dielectric constant ~1600, leakage current ~1.8310-4 A/cm2, excellent fatigue resistance, and good retention performance, indicating that high conductivity copper thin film has a promising application to high density and performance ferroelectric memory. Analysis of the leakage fitting also suggests that bulk-limited space-charge-limited conduction (SCLC) acts as the leakage current mechanism in the capacitor.
Photoluminescence enhancement of colloidal quantum dots embedded in a microcavity
Authors: Du Ling-Xiao  , Hu Lian  , Zhang Bing-Po  , Cai Xi-Kun  , Lou Teng-Gang  , Wu Hui-Zhen  ,   Department of Physics, State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310027, China
Published: December 2020

We report on the study of CdSe quantum dot microcavity formed between two distributed Bragg reflectors (DBRs). The active region consisting of CdSe quantum dots is embedded in PMMA. We use the transfer matrix method (TMM) to simulate the reflectivity spectrum of the microcavity. We demonstrate an enhancement of the spontaneous emission from the colloidal CdSe quantum dots in the microcavity. After embedding the QDs in the cavity, the full width at half maximum (FWHM) is narrowed to 7.5 nm compared with 27.9 nm of QDs in free space. The emission of the quantum dots is enhanced by a factor of 3.7 due to the microcavity effect.
Time irreversibility analysis of ECG based on symbolic relative entropy
Authors: Shen Wei  , Wang Jun  ,   Image Processing and Image Communications Key Laboratory, Nanjing University of Posts and Telecommunications, Nanjing 210003,China
Published: December 2020

Time irreversibility of electric cardiac graph(ECG) signal can reflect the physiological function and the health condition of the heart. In this paper,we propos a symbolic relative entropy method (first symbolizing and then determining the time irreversibility) to analyze the three kinds of ECG signals, i.e., normal sinus rhythm, ventricular fibrillation and sudden cardiac death from the MIT-BIH database. The results show that three kinds of signals have different time irreversibilityies, and the time irreversibility range is largest for the normal sinus rhythm, the second largest for the ventricular fibrillation, and smallest for the sudden cardiac death. Variance test results indicate that the irreversibilities of the three signals are significantly different. The results show that the relative entropy method can play a positive role in heart disease detection and diagnosis.
Human dynamics analysis in online collaborative writing
Authors: Zhao Fei  , Liu Jin-Hu  , Zha Yi-Long  , Zhou Tao  ,   Web Sciences Center, University of Electronic Science and Technology of China, Chengdu 610054, China;,   School of Economy and Management, University of Electronic Science and Technology of China, Chengdu 610054, China;,   School of Applied Mathematics, University of Electronic Science and Technology of China, Chengdu 610054, China;,   Experimental Class of International Software Professionals, University of Electronic Science and Technology of China, Chengdu 610054, China
Published: December 2020

Investigating the human online behavior has become a central issue for understanding human dynamics in recent years. In this paper we analyze the temporal and content-updating statistical properties of online collaborative writing based on Wikipedia data. Online collaborative writing is one of the important and widespread human online behaviors, which is of great apphication. Empirical result shows that the distribution of inter-event time in collaborative writing is on the multi-scale. That is to say, two time intervals that range from 1 min to 30 min and 30 min to 24 h both obey power-law distribution with exponents equal to 1.62 and 1.16 respectively, while the interval larger than 24 h obeys a distribution whose cumulative form is F()－b－alog(). More investigatons show successive updating behavior and mutual updating behavior working together to lead to the multi-scale distribution of inter-event time. Successive updating behavior leads to the power-law distribution with an exponent 1.62 of interval within 30 min while mutual updating behavior leads to the power-law distribution with an exponent 1.16 of interval ranging from 30 min to 24 h. Furthermore, we find that reverse updating repeats frequently in collaborative writing. The proportions of reversing updating and the updating size are strongly relatively reflect that the updating size is a main reason leading to the relevant content to be preserved. The bigger the updating size, the harder it would be preserved. More statistical analyses imply that watching dog and edit war exist in Wikipedia editing. Those results are very helpful to deepen the understanding of the human collective behavior, especially of the collaborative developing behavior.
Propagation, distribution and detection principle of seismic precursory signals
Authors: Lu Kun-Quan  , Hou Mei-Ying  , Wang Qiang  , Jiang Ze-Hui  , Liu Ji-Xing  ,   Beijing National Laboratory for Condensed Matter Physics, Key Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China;,   Department of Applied Physics, Harbin Institute of Technology, Harbin 150001, China;,   Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing 100190, China
Published: December 2020

The earth crust consists of tectonic plates, faults and the fault gouges at their boundaries. In the case of studying such an issue as quasi-static mechanics on the seismic precursory spreading, the crustal lithosphere must be treated as a granular system consisting of large-scale discrete grains. In the process of seismogeny, the rock blocks driven by tectonic forces induce a stick-slip motion by overcoming the friction and the boundary resistance. When the fault gouges between blocks are squeezed and their strength increases to a certain degree, the next block will be pushed to generate a stick-slip motion and the successive rock blocks move gradually in the same way. As in any granular system, the distribution and transfer of force and the movement of the rock blocks must be in the chain-like form. This model is not only reasonably deduced from the physical bases, but also supported by many actual observations. In this work the distribution of force-motion-deformation and the spreading time sequence are given with the simulated experiments and analysis. The main feature of the generated precursory information is described. The essential difference between the understanding of seismic precursor led by viewing the crustal lithosphere as granular system and that as continuum medium is presented. How to acquire effective seismic precursory information as well as how to associate it with the occurrence of earthquake is discussed. Some of the seismology problems are explained reasonably, which can be hardly understood from the continuum medium view point.
A new method of retrieving typhoon's sea level pressure fields and central positions from scatterometer-derived sea surface winds
Authors: Zhang Liang  , Huang Si-Xun  , Du Hua-Dong  ,   Institute of Meteorology, People's Liberation Army University of Science and Engineering, Nanjing 211101, China
Published: December 2020

First, UWPBL model(the university of washington planetary boundary layer model) is used to retrieve YaGi typhoon sea level pressure from sea surface wind data of SeaWinds which are obtained from QuikSCAT(called direct retrieving) and these strength results are analyzed. Then the variational method is used to decompose the sea surface winds field into two parts: vortex and irrotational environmental flow field, the UWPBL model is used again to retrieve YaGi typhoon sea level pressure from the vortex flow field, the results of typhoon central positions are analyzed by comparing the results with the results of direct retrieving, NCEP data and typhoon annual reports. It turns out that the accuracy of the typhoon sea level pressure central position is obviously improved. This method offers a new idea for the study of typhoon from microwave scatterometer data.
Tracking refractivity from radar clutter using extended Kalman filter and unscented Kalman filter
Authors: Sheng Zheng  ,   Institute of Meteorology, PLA University of Science and Technology, Nanjing 211101, China
Published: December 2020

Since the traditional statistical and physical algorithms in the inversion of refractivity from radar clutter (RFC) cannot track omni directions in real time, a new filter algorithm (extended Kalman filter and unscented Kalman filter) is proposed. The parameter equation of atmospheric duct, observation operator, state equation of filter arithmetic are derived separately. Finally, the implementation of the iterative inversion filter algorithm is derived. On the theoretical basis, two algorithms above are tested separately with or without considering the variation of refractivity with time. The experimental result indicates that unscented Kalman filter is suited to solve the nonlinear inversion problem, which has significance in theoretical foundation and technological support for practical applications for the future.
X-ray pulsar-based navigation semi-physical simulation experiment system
Authors: Su Zhe  , Xu Lu-Ping  , Wang Ting  ,   School of Electronic Engineering, Xidian University, Xi’an 710071, China
Published: December 2020

For the huge costs, the space flight experiment cannot be realized in the preliminary step of X-ray pulsar based navigation (XPNAV) research. So, a kind of XPNAV semi-physical simulation experiment system is designed in this paper. This system is composed of two parts: the simulation of pulsar signal and the calculation of navigation parameters. In the first part, the time when X-ray photon arrives at the solar system barycenter is modeled by non-homogeneous Poisson process, then the output pulse of X-ray detector can be simulated by time transformation. In the second part, the navigation information included in the pulses which have been simulated in the first part can be reached by using the Delta-Correction method. This system can be used to simulate four pulsar signals simultaneously, and to study the process of signal processing and parameters calculation of XPNAV at photo level. This system has the advantage of low costs and high simulation accuracy, and provides a reference for the design of prototype in space flight experiment.
The approximate homotopy symmetry reduction for far-field model equation
Authors: Jiao Xiao-Yu  ,   School of Applied Mathematics, Nanjing University of Finance and Economics, Nanjing 210046, China; Department of Physics, Shanghai Jiaotong University, Shanghai 200240, China
Published: December 2020

The far-field model equation is investigated by the approximate homotopy symmetry method. Homotopy series solutions are constructed through summarizing the relevant general formulas for similarity reduction solutions and similarity reduction equations of differernt orders. Similarity reduction equations of different orders are linear variable coefficients ordinary differential equations, and can be solved one by one from zero-order similarity reduction equations. The auxiliary parameter in the homotopy model affects convergence of homotopy series solutions.
A method of constructing peaked soliton solution of nonlinear wave equation by using smooth soliton solution
Authors: Liu Yu  , Liu Wei-Qing  ,   Henan Electric Power Research Institute, Zhengzhou 450052, China;,   School of Mathematics and Statistics, Henan University of Science and Technology, Luoyang 471003, China
Published: December 2020

We propose a method of obtaining peakon solution from bell-shape smooth soliton (or solitary wave)solution, i.e. constructing directly an ansatz solution of peakon according to the well-known bell-shape smooth soliton solution and then determining the coefficients in ansatz solution. The method is verified to be feasible for four nonlinear wave equations and one set of equations. The bell-shape smooth soliton (or solitary wave)solution and peakon solution can exist in the same expression and the expressions of peakon solutions include those of the bell-shape smooth soliton solutions and the latter are the special cases of the former.
Density correlation effect of incoherent ultracold atoms in an optical lattice
Authors: Xu Zhi-Jun  , Liu Xia-Yin  ,   Department of Applied Physics, Zhejiang University of Technology, Hangzhou 310032, China
Published: December 2020

Atoms in the Mott insulator state trapped in an optical lattice are incoherence matter wave source. It is not the first-order, but the second-order interference effect (density correlation) that will appear for this incoherence wave source after being released. A density correlation function of the freely expanding ultracold gases is obtained theoretically, which presents sharp peaks of interference, and the stripes structure is similar to the diffraction gratings. It is further pointed out that the peak structure of the density correlation function depends on the relative position between two detectors. The phenomenon of subwavelength interference of matter waves is also proposed in this paper.
Analysis and implementation of memristor chaotic circuit
Authors: Bao Bo-Cheng  , Hu Wen  , Xu Jian-Ping  , Liu Zhong  , Zou Ling  ,   School of Information Science and Engineering, Changzhou University, Changzhou 213164, China;,   College of Electronic and Information Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China;,   School of Electrical Engineering, Southwest Jiaotong University, Chengdu 610031, China;,   Department of Electronic Engineering, Nanjing University of Science and Technology, Nanjing 210094, China
Published: December 2020

Memristor with memory function is the fourth fundamental two-terminal circuit element, besides resistor, capacitor and inductor. In this paper, a smooth flux-controlled memristor is described by a monotone-increasing nonlinearity curve in the -q plane, and it has an italic type 8 like voltage current relation curve that looks like a pinched hysteresis loop characteristics. By replacing Chua's diode with an active memristor consisting of a smooth flux-controlled memristor and a negative conductance, a memristor based chaotic oscillation is derived from Chua's circuit. Furthermore, the equivalent circuit implementation form for the active memristor is designed by utilizing conventional components such as operational amplifiers and multipliers. The results from theoretical analysis, numerical simulations and circuit simulations are completely identical with each other, and demonstrate that the dynamical behaviors of the memristor chaotic circuit are dependent on the memristor initial state, showing different orbits such as chaotic oscillation, periodic oscillation and stable sink under different initial states.
Adaptive chaotic control of permanent magnet synchronous motor
Authors: Li Chun-Lai  , Yu Si-Min  ,   School of Automation, Guangdong University of Technology, Guangzhou 510006, China;,   College of Physics and Electronics, Hunan Institute of Science and Technology, Yueyang 414006, China
Published: December 2020

Based on the LaSalle's invariant set theorem, an adaptive controller is constructed to acquire the chaotic control for the permanent magnet synchronous motor. And then a extended adaptive controller is developed by introducing a control strength factor. In comparison with the previous schemes, the present control method is simple, flexible, and is applicable in practice because of reduced control cost. Simulation results are presented to show the effectiveness and the robust of the proposed method.
Exact solutions and localized excitations of (3+1) -dimensional Jimbo-Miwa equation
Authors: Lei Jun  , Ma Song-Hua  , Fang Jian-Ping  ,   Department of Physics, Lishui University, Lishui 323000, Ghina
Published: December 2020

With the help of the symbolic computation system Maple and a projective equation and a linear variable separation method, new exact solutions of the (3+1) -dimensional Jimbo-Miwa equation are derived. Based on the derived solitary wave solution, some novel localized excitations are investigated.
An epidemic spreading model in adaptive networks based on cellular automata
Authors: Song Yu-Rong  , Jiang Guo-Ping  , Xu Jia-Gang  ,   College of Automation, Nanjing University of Posts and Telecommunications, Nanjing 210003, China
Published: December 2020

An adaptive network is a kind of co-evolutionary network in which the behaviors of nodes and the dynamics of the network affect each other. A susceptible-infected-susceptible epidemics spreading model in the adaptive network is proposed using cellular automata. Under different rewriting rules for avoiding the epidemic spreading, the changes in epidemic dynamics and the properties of the network statistic are investigated. The simulation results show that the introduction of rewiring can slow down the spreading speed of epidemic and suppress the infected scale of epidemic. The random rewiring rules make the properties of an original network with any topology tend to those of a random network. Furthermore, the proposed cellular automata model can clearly exhibit the phenomenon of bi-stability in epidemic dynamics.
The study of structure characteristics of GeTe and GeSe molecules under the external electric field
Authors: Huang Duo-Hui  , Wang Fan-Hou  , Cheng Xiao-Hong  , Wan Ming-Jie  , Jiang Gang  ,   Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, China;,   Laboratory of Computational Physics, Yibin University, Yibin 644000, China
Published: December 2020

Equilibrium structures of the GeTe and GeSe ground state molecules are obtained by employing the local spin density approximation method with 6-311++G** basis sets for Ge and SDB-cc-pVTZ for Te and Se. Also obtained are the equilibrium geometry, the highest occupied molecular orbital(HOMO) energy level, the lowest unoccupied molecular orbital(LUMO)energy level, the energy gap, the harmonic frequency and the infrared intensity of GeTe and GeSe ground state molecules under different electric fields. On the basis of the above calculation, the excited states of GeTe and GeSe molecules under different electric fields are also investigated by using the single-excitation configuration interaction-local spin density approximation method. The results show that the equilibrium internuclear distance and the intensity of infrared are found to increase, but the total energy and harmonic frequency are proved to decrease with the increase of positive direction electric field. The HOMO energy EH of GeTe molecule is higher than that of GeSe molecule under electric fields ranging from 0 to 2.05691010 V m-1. For GeTe and GeSe molecules, their difference in EH gradually increases with the increase of positive direction electric field. The LUMO energy EL of GeTe molecule is lower than that of GeSe molecule, and their LUMO energies are found to increase with the increase of positive direction electric field. The energy gap of GeTe is low than that of GeSe, and their energy gaps always decrease with the increase the negative direction electric field. The magnitude and the direction of the external electric field have important effects on excitation energy, oscillator strength and wavelength.
Pair interactions of detonation products at high pressure and high temperature
Authors: Zhao Yan-Hong  , Liu Hai-Feng  , Zhang Gong-Mu  , Zhang Guang-Cai  ,   Institute of Applied Physics and Computational Mathematics, Beijing 100094, China
Published: December 2020

In this paper, we present a method of determuning the potentials of molecules and dissociation products by shock wave data. The potentials are calculated by the Rosss modification of hard-sphere variation theory at low pressure and the statistical mechanical chemical equilibrium method at high pressure. Our results are in better agreement with the experimental data than the results obtained from the corresponding states theory.
Photoassociation reaction of H+D+ in two chirped pulses
Authors: Niu Ying-Yu  , Wang Rong  , Xiu Jun-Ling  ,   School of Science, Dalian Jiaotong University, Dalian 116028, China
Published: December 2020

The photoassociation reaction H+D+ induced by two chirped pulses is theoretically studied. The first pulse is employed to accelerate the collision pairs, and the second pulse is used to enhance the yield ratio of HD+. The optimal parameters of the second pulse and the population of product HD+ depend on the chirp rate of the first pulse. The population of the product HD+ can be controlled by the delay time between the two laser pulses.
Thrust prediction of propellantless microwave thruster operating on variational power
Authors: Yang Juan  , Li Peng-Fei  , Yang Le  ,   College of Astronautics, Northwestern Polytechnical University, Xi'an 710072, China
Published: December 2020

Based on classical electrodynamics theory, the theoretical prediction equations for calculating the thrust of propellanless microwave thruster is deduced according to Maxwell equation and tress tensor. With the calculated electromagnetic fields by using finite element analysis software, the electromagnetic field distribution of a defined thruster cavity operating in a specific resonant mode under different electromagnetic powers is calculated to predict its thrust according to the deduced method. It is found that the thrust increases with the increase of the electromagnetic power and the total thrust is determined by the magnetic thrust. The net thrust will rang from 20 to 250 mN in a power range from 20 to 200 W.
Image diffusion filtering based on dual tree complex wavelet and wave atoms
Authors: Liu Jin-Hua  , She Kun  ,   School of Computer Science and Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China
Published: December 2020

The nonlinear diffusion of image filtering is from the idea of heat equations. Its key point is to choose a proper diffusion coefficient and control the diffusion direction. In the previous models, the diffusivity depends on the gradients of images, thus it is easily affected by noises. Furthermore, many fine structures such as textures are prone to being taken for noise and then will be removed. In order to overcome these shortcomings, first, in this paper we introduce a novel computational technique for diffusivity by using the dual tree complex wavelet transform. Second, we develop a nonlinear diffusion model for image filtering. Finally, an image diffusion filtering method based on the dual tree complex wavelet transform and wave atoms thresholding is presented, and also compared with the previous methods. Experimental results show that many features of image such as edges and textures can be preserved well after filtering via the proposed algorithm.
Path length coded coherence combination for three-dimensional superresolution
Authors: Shang Zai-Ming  , Ding Zhi-Hua  , Wang Ling  , Liu Yong  ,   State Key Laboratory of Modern Optical Instrumentation, Zhejiang University, Hangzhou 310027, China
Published: December 2020

Axial resolution and traverse resolution in optical coherence tomography (OCT) imaging are determined by different factors, while axial resolution is determined by both the coherence length of light source and the beam-focusing condition, and traverse resolution is determined by the beam-focusing condition of the sample arm. In the main approaches to axial resolution improvement in OCT, a light source with a broaden bandwidth is used and coherence gating is combined with apodization, which cannot improve the traverse resolution. A method is introduced to increase both the axial resolution and traverse resolution simultaneously in an OCT system by the path length code and coherent compounding method. Different effective functions are formed by adding a path length coding lens in to the proposed OCT system, which are corresponding to different path lengths. Owing to the intrinsic ability to differentiate path lengths, we can obtain several images of the same sample, corresponding to the different effective functions simultaneously. By adding these functions through numerically controlling their relative contributions, we can finally obtain a coherent compounding signal with three-dimensional superresolutions of axial resolution and traverse resolution. Compared with the previous approaches, the path length code and coherent compounding method is very easy to operate and its cost is very low, which can not only avoid the high cost and inconvenience in implantation, but also increase both axial and traverse resolutions simultaneously.
High efficiency tandem-pumped fiber amplifier
Authors: Xiao Hu  , Leng Jin-Yong  , Wu Wu-Ming  , Wang Xiao-Lin  , Ma Yan-Xing  , Zhou Pu  , Xu Xiao-Jun  , Zhao Guo-Min  ,   College of Opto-electric Science and Engineering, National University of Defense Technology, Changsha 410073, China
Published: December 2020

A 1020 nm fiber laser is designed based on fiber Bragg grating and then its output power is boosted to 590 mW through a two-stage amplifier. A tandem pumping fiber amplifier is constructed with the 1020 nm laser used as a pump source. The output power and the efficiency of the amplifier are measured with different lengths of gain fiber. A 385 mW maximum output power with an 81% slope-efficiency is achieved when the gain fiber is 8.5 m. The output power and the efficiency of a traditional amplifier in which 976 nm diode laser is used as a pump source are also measured. The experimental results indicate that tandem pumping fiber amplifier can achieve a higher efficiency than traditional fiber amplifier.