bluuebunny/crossref_metadata_2025 huggingface dataset:
Correlations between the valence electron structure and melt pointing and cohesive energies of rare earth metals
Authors: Meng Zhen-Hua  , Li Jun-Bin  , Guo Yong-Quan  , Wang Yi  ,   North China Electric Power University, School of Energy Power and Mechanical Engineering, Beijing 102206, China
Published: December 2020

Rare earth element is one kind of strategic materials. Some rare earth elements have been industrialized. They play major roles in permanent magnetism material, lightening, catalysis and hydrogen storage material. In order to understand the rare earth elements more, it is necessary to study the structures of the valence electrons and atoms of them. The valence electron structures and properties of yttrium, scandium and lanthanum group rare earth elements are studied with the empirical electron theory (EET). Based on the valence electron parameters, the melting points and cohesive energies of these rare earth elements are calculated. The calculations accord with those of the measurements. According to the analyses of EET, the structures and the physical properties of rare earth elements depend on the electron emission or transformation between the lattice-electrons and coherent electrons in outer orbital. It is exhibited that the melting point tends to increase with the lattice electron-covalent electron transformation, however, the valence status of rare earth element affects significantly the electron distribution and property. The covalent electron hoppings occur at divalent europium, ytterbium and samarium, and their melting points are related to the electron transformation covalence-electrons. It is different from the others with trivalent status. The theoretical analysis reveals that the cohesive energy is related to the 4f electrons. The contribution to cohesive energy increases with the number of 4f electrons increasing, which may be due to the shrinking effect of the atomic radius for the lanthanum group. The study implies that the characteriscs of rare earth element are due to the relation between their melt pointing and conhesive energy and electronic structure.
First-principles study on the electronic structure and optical properties of YFeO3
Authors: Song Qing-Gong  , Liu Li-Wei  , Zhao Hui  , Yan Hui-Yu  , Du Quan-Guo  ,   Institute of Low Dimensional Materials and Technology, College of Science, Civil Aviation University of China, Tianjin 300300, China;,   College of Science, Hebei University of Technology, Tianjin 300130, China
Published: December 2020

Rare-earth orthoferrites (such as YFeO3) with orthorhombic perovskite-type structure are promising candidates in the fields of electrode materials, gas sensors and photocatalysts. The geometric structure, the electronic structure and the optical properties of YFeO3 crystal are investigated by using the plane-wave pseudo-potential method, with the scheme of generalized gradient approximation, revised Perdew-Burke-Emzerhof exchange-correlation potential and ultrasoft pseudopotential. The obtained lattice parameters are in good accordance with experimental results reported. The results confirm that YFeO3 crystal is a direct semiconductor with a gap (Eg) of about 2.22 eV, based on the analyses about band structure, density of state, dielectric function, absorption coefficient, and photoconductivity. It is clarified that YFeO3 crystal and nanocrystalline possess good photocatalytic activities for visible light.
Influences of the demagnetizing field on dynamic behaviors of the magnetic domain wall in ferromagnetic nanowires
Authors: Fan Zhe  , Ma Xiao-Ping  , Lee Sang-Hyuk  , Shim Je-Ho  , Piao Hong-Guang  , Kim Dong-Hyun  ,   College of Science, Huaihai Institute of Technology, Lianyunguang 222005, China;,   Department of Physics, Chungbuk National University, Cheongju 361-763, South Korea
Published: December 2020

Understanding of magnetic domain wall dynamic behavior is one of the important issues in the realization of spintronic device based on domain wall motion. We investigate the dynamic behaviors of the magnetic domain wall propagation in L-shaped ferromagnetic nanowires under external magnetic driving fields. By micromagnetic simulation, we observe a dynamic characteristic of the magnetic domain wall in a ferromagnetic nanowire with varying the external field. By changing the nanowire thickness, we examine the influence of the demagnetizing field from the nanowire surface on the domain wall dynamics under a magnetic driving field after Walker breakdown field. Using an auxilliary magnetic field perpendicular to the nanowires, we analyze the effect of the demagnetizing field on the domain wall dynamic behaviors. The results show that the stronger external field or the thicker nanowire can enhance the generation of the demagnetizing field on the nanowire surface, leading to the occurrence of the Walker breakdown phenomenon with the periodic change of the inner spin structure of the domain wall during the domain wall propagation in the nanowires. By using an auxilliary magnetic field perpendicular to the nanowires, we find that the strength and the direction of the demagnetizing field can be modulated. It implies that the dynamic behavior of domain wall propagation in the nanowire is controllable.
Crossings of Lamb modes in lead zinc niobate-lead titanate crystal plates
Authors: Chen Chuan-Wen  , Xiang Yang  ,   College of Science, Northeast Forestry University, Harbin 150040, China;,   College of Information Science and Engineering, Huaqiao University, Xiamen 361021, China
Published: December 2020

Frequency dispersions of Lamb waves in [001]c and [011]c polarized lead zinc niobate-lead titanate crystal free infinite plates are studied based on the partial wave theory. Multiple crossings between symmetric and antisymmetric Lamb modes are found only in [001]c polarized crystals, and most of the dispersion relations would exhibit the same rule as that in lead magnesium niobate-lead titanate crystals. It is found that multiple crossings between A0 and S0 modes are directly related to the multivalued quasishear vertical slowness curves. A pair of complex conjugate roots of the wave number in the x3 direction is found in a certain area. Equation of elastic constants is obtained when A0 and S0 modes cross under this condition, which can be conveniently used to judge whether A0 and S0 modes cross for crystals with orthogonal and tetragonal symmetries.
The fabrication of Er3+/Ce3+ co-doped tellurite- bismuth glasses and the improvement of spectroscopic properties
Authors: Wang Sen  , Zhou Ya-Xun  , Dai Shi-Xun  , Wang Xun-Si  , Shen Xiang  , Chen Fei-Fei  , Xu Xing-Chen  ,   College of Information Science and Engineering, Ningbo University, Ningbo 315211, China
Published: December 2020

A series of 80TeO2-10Bi2O3-10TiO2-0.5Er2O3-xCe2O3 (x=0, 0.25, 0.5, 0.75, 1.0 mol%) and (80-y) TeO2-10Bi2O3-10TiO2-yWO3-0.5Er2O3-0.75Ce2O3 (y=3, 6, 9, 12 mol%) tellurite-bismuth glasses are prepared by the conventional high-temperature melting and annealing method. The absorption spectra of 400-1700 nm, upconversion spectra and 1.53 m band fluorescence spectra under the excitation of 975 nm, the 4I11/2 and 4I13/2 level fluorescence lifetimes of Er3+ under the excitation of 808 nm, and the Raman spectra of doping-free glass samples are measured. Meanwhile, the spectroscopic parameters of Er3+ are calculated and analyzed with the help of Judd-Ofelt theory and McCumber theory. The results indicate that the upconversion fluorescence can be suppressed efficiently and the 1.53 m band fluorescence can be enhanced evidently, owing to the energy transfer from Er3 +: 4I11/2Ce3+:2F5/2 levels when the Ce3+ ions are introduced into the Er3+-doped tellurite-bismuth glasses. Moreover, the 1.53 m band fluorescence intensity can be improved and the fluorescence spectral width can be broadened further when an appropriate amount of WO3 component is introduced. The above research results are of theoretical significance for obtaining the tellurite-bismuth glasses with excellent spectroscopic properties, which are used for the 1.53 m broadband Erbium-doped optical fiber amplifier.
Terahertz dual-core photonic band-gap fiber directional coupler
Authors: Bai Jin-Jun  , Wang Chang-Hui  , Hou Yu  , Fan Fei  , Chang Sheng-Jiang  ,   School of Electronics and Information Engineering, Tianjin Polytechnic University, Tianjin 300160, China;,   Institute of Modern Optics, Nankai University, Tianjin 300387, China
Published: December 2020

A low-loss and broadband terahertz twin-core photonic band-gap fiber directional coupler is proposed, which consists of a cladding with a triangular lattice array of sub-wavelength air rods and two cores formed respectively by omitting seven nearby air rods. The group velocity dispersion, the coupling and the loss of the fibers are investigated by using a full-vector finite element method. The numerical simulations show that the loss coefficient of the coupler is less than 0.021 cm-1, and the coupling broadband of 0.14 THz can be realized. The directional coupler has potential applications in terahertz communication systems, such as filtering, wavelength-division multiplexing, polarization isolation, switching and so on.
The families of Lagrangians of a Painleve equation
Authors: Ding Guang-Tao  ,   The College of Physics and Electronic Information, Anhui Normal University, Wuhu 241000, China
Published: December 2020

By use of the method to construct the Lagrangian from the first integral, two families of Lagrangians and some Lagrangians and Hamiltonians are obtained for a class of Painleve equations.
Infinite sequence soliton-like exact solutions of Nizhnik-Novikov-Vesselov equation
Authors: Taogetusang  , Bai Yu-Mei  ,   College of Mathematical, Inner Mongolia University for Nationalities, Tongliao 028043, China;,   College of Mathematical Science, Inner Mongolia Normal University, Huhhot 010022, China
Published: December 2020

To construct the infinite sequence soliton-like exact solutions of nonlinear evolution equations and develop the characteristics of constructivity and mechanization of the first kind of elliptic equation, new type of solutions and the corresponding Bcklund transformation of the equation are presented. Based on this, infinite sequence soliton-like exact solutions of Nizhnik-Novikov-Vesselov equation are obtained with the help of symbolic computation system Mathematica, which includes infinite sequence smooth soliton-like solutions, infinite sequence peak soliton-like solutions and infinite sequence compact soliton-like solutions.
Simulation of two-dimensional many-particle hardcore bosons by using the quantum Monte Carlo method
Authors: Xu Ying  , Li Jin-Bin  ,   College of Science, Nanjing University of Aeronautics and Astronautics, Nanjing 211100, China
Published: December 2020

In this paper, the stochastic series expansion quantum Monte Carlo method is employed to investigate the thermodynamic properties of hardcore Bose-Hubbard model in two-dimensional space. The two-dimensional hardcore Bose-Hubbard model can be mapped into the two-dimensional antiferromagnetic quasi-Heisenberg model under transform of bosonic operators. There is an additional term which is proportional to the total number of sites compared with real Heisenberg model and it is difficult for simulation. Using a nonlocal operator-loop update, it allows one to simulate thousands of sites. Our simulation results show that, first, energy decreases with the increase of density of particles in a range from 0 to 0.5, and finally approaches to a fixed value. Moreover, with the size of square lattice increasing, energy also increases. Second, when we fix the system size, energy and magnetization increase with temperature, but not with of chemical potential. When we increase the system size, energy increases, while, the magnetization decreases. Third, specific heat is independent of chemical potential, but it dramatically increases with temperature and approaches to a peak, then decreases slowly. According to Landau theory of superfluidity, the tends of curve for energy and specific heat fit the research of He II in the Landau two-fluid model. Fourth, different square lattice linear system sizes have a little influence on tiny differences to the reciprocal of uniform susceptibility. There are small fluctuations in a range from 0 to 0.5(J/kB), where J is the coupling energy, kB is the Boltzmann constant, but the reciprocal of uniform susceptibility increases with temperature increasing in a range from 0.5 to 2(J/kB). The tends of curve are similar to those of Kondo effect.
Statistical entropy of reissner-nordstrm-de sitter black hole by generalized uncertainty principle
Authors: Huang Hai  , He Feng  , Sun Hang-Bin  ,   College of Physics and Electronic Science, Hunan University of Science and Technology, Xiangtan 411201, China
Published: December 2020

Statistical entropy of scalar field outside Reissner-Nordstrm-de Sitter black hole is computed by the equation of state density corrected by the generalized uncertainty principle and by Wentzel-Kramers-Brillouin approximation method. The result shows that the entropy is proportional to the sum of the internal, the external and the cosmological horizon areas, which accords with these calculated by other methods. It shows internal relation between the entropy of black hole and horizon area. The entropy of black hole is the entropy of quantum state on horizon, which is a quantum effect.
Exact solutions and soliton excitations for the (2+1)-dimensional Bogoyavlenskii-Schiff system
Authors: Zeng Wen-Li  , Ma Song-Hua  , Ren Qing-Bao  ,   Department of Physics, Zhejiang Lishui University, Lishui 323000, China
Published: December 2020

With the help of the symbolic computation system Maple and using the improved projective method and the variable separation method, a series of excitations of the (2+1)-dimensional Bogoyavlenskii-Schiff system is derived. According to the derived solitary wave solution, we obtain some novel localized excitations of the system.
Lie symmetry and their conserved quantities of Tznoff equations for the vairable mass nonholonomic systems
Authors: Zheng Shi-Wang  , Wang Jian-Bo  , Chen Xiang-Wei  , Li Yan-Min  , Xie Jia-Fang  ,   School of Physics and Electrical Information, Shangqiu Teachers College, Shangqiu 476000, China;,   College of Science, North China University of Technology, Beijing 100144, China
Published: December 2020

The operational system of the spacecraft is general a variable mass one, of which the symmetry and the conserved quantity imply physical rules of the space system. In this paper, Tznoff equations of the variable mass nonholonomic system are derived, from which the Lie symmetries of Tznoff equations for the variable mass nonholonomic system and conserved quantities are derived and are researched. The function expressions of conserved quantities and the criterion equations which deduce these conserved quantities are presented. This result has some theoretical value for further research of the conservation laws obeyed by the variable mass system.
Theoretical study of two-tone single frequency fiber amplifier with gain competition
Authors: Du Wen-Bo  , Leng Jin-Yong  , Zhu Jia-Jian  , Zhou Pu  , Xu Xiao-Jun  , Shu Bo-Hong  ,   College of Optoelectronic Science and Engineering, National University of Defense Technology, Changsha 410073, China
Published: December 2020

Introducing the gain competition is an effective way to suppress stimulated Brillouin scattering (SBS) in single frequency fiber amplifier. Steady rate equation describing two-tone single frequency Yb-doped double cladding fiber amplifier with gain competition is deduced based on single frequency amplifier. A theoretical model of this kind of amplifier is set up. With this model, simulation is performed to analyze the influences of wavelength difference between signals, signal power ratio, pump configuration and length of gain fiber on output efficiency of single frequency laser, and the effect of SBS suppression.
Conceptual research on modifications of indirect drive laser facilities for shock ignition
Authors: Yuan Qiang  , Wei Xiao-Feng  , Zhang Xiao-Min  , Zhang Xin  , Zhao Jun-Pu  , Huang Wen-Hui  , Hu Dong-Xia  ,   Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900, China;,   Department of Engineering Physics, Tsinghua University, Beijing 100084, China
Published: December 2020

Shock ignition is a new concept for assembling and igniting thermonuclear fuel, in which compressed fusion fuel is separately ignited by a strong convergent shock launched in the target at the end of compression phase by a final intense laser pulse. Because of compression and ignition decoupling, target implosion velocities are significantly lower than those required for conventional hotspot ignition. As a result, shock ignition has the advantages of a low ignition energy threshold, high gain and good hydrodynamic stability properties. It offers a possibility for a high gain inertial confinement fusion to be used as green energy in the future, and could be tested on the projecting indirect drive laser fusion facilities like Shenguang-III facility (SG-III) in China. In this paper, we present the requirements for laser system used for shock ignition, delineate the critical issues and describe the research and development program that must be performed in order to test the high gain shock ignition in the future term.
Characterization and chemical/biosensing application of a high-sensitivity integrated optical polarimetric interferometer
Authors: Lu Dan-Feng  , Qi Zhi-Mei  ,   State Key Laboratory of Transducer Technology, Institute of Electronics, Chinese Academy of Sciences, Beijing 100190, China
Published: December 2020

A tapered thin film of Ta2O5 is sputtered on a single-mode slab glass waveguide to form a composite optical waveguide (COWG) for serving as a prism-coupled integrated optical polarimetric interferometer. The relationship between the refractive-index sensitivity (SRI) of the interferometer and the equivalent thickness (Teq) for the tapered layer of Ta2O5 is theoretically analyzed based on a four-layer homogeneous waveguide model. A comparison of the measured SRI with the simulated data leads to Teq 33.021 nm for the COWG used. The sensitivity of the interferometer to thickness of the protein adlayer is determined to be Sab (2.412 2)/nm. The acetic-acid concentration of a commercial Chinese vinegar is investigated, for the first time, by use of the interferometer combined with the Lorentz-Lorenz effective-medium theory. Water and methanol adulterations of a commercial Chinese liquor are detected with the interferometer. The results indicate that the refractive-index change induced by the adulteration is a quasi-linear function of the adulteration amount. Both the dynamic adsorption process of butyrylcholinesterase and the self-assembly process of cytochrome c/PSS multilayer film are monitored in real time with the sensor. The protein surface coverage is obtained from the combination of the measured phase-difference change and the adlayer-thickness sensitivity.
Measurement of the argon-gas-induced broadening and shifting of the barium Rydberg levels by two-photon resonant nondegenerate four-wave mixing
Authors: Sun Jiang  , Sun Juan  , Wang Ying  , Su Hong-Xin  ,   College of Physical Science and Technology, Hebei University, Baoding 071002, China;,   College of Mathematics and Computer Science, Hebei University, Baoding 071002, China
Published: December 2020

We apply two-photon resonant nondegenerate four-wave mixing with a resonant intermediate state for observing the broadening and the shifting of the barium Rydberg 6snd 1D2 series by collision with argon. The collision broadenings and the collision shifting cross sections are measured for n=1633. This technique is a purely optical means, and can achieve Doppler-free resolution of narrow spectral structures of Rydberg levels when the incident lasers have narrow bandwidths. Different from other experimental methods of studying the pressure dependence of the longitudinal relaxation rate of Rydberg states, our method is to investigate the pressure dependence of the transverse relaxation rate of the transition.
Numerical simulation of direct current method of measuring thermal conductivities of thin films
Authors: Li Wei-Zhi  , Wang Jun  ,   School of Optoelectronic Information, University of Electronic Science and Technology of China, Chengdu 610054, China
Published: December 2020

Thermal conductivity is one of the most important physical properties of thin films. Different from two- or three-dimensional measurement structures in most reports, in this work, one-dimensional (1D) two-end supported cantilever beam is provided. The structure of cantilever includes a metal heater (which also serves as a thermometer) and thin film(s) underneath for measurement. 1D heat flow equation is employed to obtain the expression of temperature rise distribution (T(x)) along the cantilever beam and voltage drop changes along the heater (U) when a direct current (DC) follows in the heater. To confirm the correctness of theoretical deduction, ANSYS finite element software is employed to simulate T(x) and U. Results demonstrate that the simulations are in good agreement with the theoretic calculations obtained from expressions of T(x) and U. Compared with conventional 3-times frequency (3 ) method, the DC method with 1D cantilever beam is relatively simple and accurate.
The study of hydrodynamic instability growth measurement
Authors: Yuan Yong-Teng  , Hao Yi-Dan  , Hou Li-Fei  , Tu Shao-Yong  , Deng Bo  , Hu Xin  , Yi Rong-Qing  , Cao Zhu-Rong  , Jiang Shao-En  , Liu Shen-Ye  , Ding Yong-Kun  , Miao Wen-Yong  ,   Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

In inertial confinement fusion experiments, the measurement of hydrodynamic instability growth factor is an important means of studying hydrodynamic instability. In this paper we use the calibration of the sample to gain the modulation transfer function of framing camera at a given space frequency. The calibration results are employed to measure the absolute hydrodynamic instability growth of sinusoidally perturbed sample, under the condition of the same configure, and the growth factors at different times are given. The results show that the method of measuring the absolute hydroponics instability growth is established successfully.
Study on the spatial distribution of implosion shell based on the inverse Abel transform
Authors: Dong Jian-Jun  , Cao Zhu-Rong  , Chen Bo-Lun  , Huang Tian-Xuan  , Miao Wen-Yong  , Zhang Ji-Yan  , Liu Shen-Ye  , Jiang Shao-En  , Ding Yong-Kun  , Gu Yu-Qiu  , Shan Lian-Qiang  ,   Laser Fusion Research Center, China Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

A method of solving spatial distribution of shell density by inverse Abel transform is presented. CH sphere imaging on the micro-focus X-ray source is implanted to test the method of inverse Abel transform. The reversion of shell density is in agreement with real density, which verifies the correctness of the method. The 16-fram implosion target images are processed by inverse Abel transform, and the distributions of compressed shell density at different times are obtained. Qualitative analysis of back-lighter distribution, pinhole imaging and variation of shell thickness is proposed for inverse Abel transform.
Dynamic recrystallization phenomenon in hot-working process by multi-phase-field model
Authors: Xu Shu-Jie  , Shi Chun-Sheng  , Zhao Nai-Qin  , Liu En-Zuo  ,   Tianjin Key Laboratory of Composite and Functional Materials, School of Materials Science and Engineering, Tianjin University, Tianjin 300072, China
Published: December 2020

Evolution of the dynamic recrystallization microstructure in the hot working process of metal is difficult to observe in real time experimentally. Based on Ginzburg-Landau kinetic equation, a physical metallurgy model with coupling multi-phase field method and the dislocation density calculation is used to simulate dynamic recrystallization in the thermal processing. The dynamic recrystallization processes at the different temperatures and different strain rates are investigated. The reason for the stress-strain curve changing from single peak state to the multi-peak state is explained. In addition, we systematically simulate the process of multi-stage deformation and the effect of static recovery on dynamic recrystallization, and analyze the influence of thermal processing parameters on the kinetics of dynamic recrystallization. The simulation results show that the grain size increases during suspension of deformation, and higher deformation temperature and lower deformation strain rate can accelerate the process of dynamic recrystallization.
Inducing magnetic monopole in conductor and topological insulator by point charge
Authors: Zeng Lun-Wu  , Song Run-Xia  ,   Jiangsu Key Laboratory for Intelligent Agricultural Equipment, College of Engineering, Nanjing Agricultural University, Nanjing 210031, China
Published: December 2020

Using the electric potential and the magnetic scalar potential formulas which contain Bessel function of zero-order of first kind and the constitute relations of topological insulator, we derive the induced electric potentials and induced magnetic scalar potentials which are induced by point electric charge in dielectric, topological insulator and earthing conductor. Further research shows that the induced magnetic monopoles and the induced electric charges are induced in dielectric, topological insulator and earthing conductor; the positive and negative induced magnetic monopoles and electric charges and their magnitudes are determined not only by the material parameter, point electric charge, but also by the space of the induced electric charge and induced magnetic monopole.
A novel Y element thick-screen frequency selective surfaces with stable performance
Authors: Tang Guang-Ming  , Miao Jun-Gang  , Dong Jin-Ming  , Hu Xiao-Qing  ,   School of Electronic and Information Engineering, Beihang University, Beijing 100191, China
Published: December 2020

Thick frequency selective surface has potential applications in the stealth curved streamlined radomes because it has advantages in broadening bandwidth and overcoming multi-layer FSS shortcoming of complex structure and low transmittance of central frequency due to the cascade. However, there are a drift of central frequency in a wide range of incident angle and an unsteadiness of polarization at big incident angle. To solve the problem, in this paper we provide a novel Y element thick FSS. The structure is analyzed using mode matching method. The bandwidth, the central frequency and its transmittance of the structure are investigated when some parameters including the incidence angle of TE and TM waves and the polarization at big incident angle are changed. The novel Y element thick FSS has better transmission properties with polarization independence and incident angle independence. The novel structure provides a valuable reference for the application in stealth curved streamlined radomes.
Action potential initial dynamical mechanism analysis in a minimum neuron model exposure to TMS induced electric field
Authors: Jin Qi-Tao  , Wang Jiang  , Yi Guo-Sheng  , Li Hui-Yan  , Deng Bin  , Wei Xi-Le  , Che Yan-Qiu  ,   School of Electrical and Automation Engineering, Tianjin University, Tianjin 300072, China;,   School of Automation and Electrical Engineering, Tianjin University of Technology and Education, Tianjin 300222, China
Published: December 2020

Transcranial magnetic stimulation (TMS) is a kind of brain stimulation method of producing magnetic field at the designated area of brain employing electromagnetic coils. The principle of TMS is to apply an electric field which is generated through the electromagnetic induction to neuron, thereby influencing the excitability of neuron. Though it has been used for decades, its underlying mechanism, i.e., how TMS induction electric field changes neuronal excitability, is still unknown. To address this problem, we establish a minimum neuron model under action of TMS induced electric field, analyze the mechanism from the viewpoint of action potential initial dynamical mechanism which has been proved to be the decision factor of neural coding in previous studies. Through phase plane and bifurcation analysis, we reveal the dynamical mechanism of different firing patterns of neuron. Finally, we find that the physiological basis of different excitabilities under action of TMS induced electric field, which is the different outcomes of competition between ion currents of neuron with different kinetic behaviors in sub-threshold potential.
Modeling of X-ray pulsar cumulation profile and signal identification
Authors: Xie Qiang  , Xu Lu-Ping  , Zhang Hua  , Luo Nan  ,   School of Electronic Engineering, Xidian University, Xi'an 710071, China
Published: December 2020

In order to reduce the observation time of X-ray pulsar signal identification, a new identification algorithm based on the photon distribution statistics is proposed. The influence of cumulation period variation on photons distribution is analyzed, according to whether the cumulation period is correct, two kinds of Poisson models are developed to characterize the cumulation profiles. The photon distribution statistics is constructed, and the difference of photon distribution statistics between two kinds of profiles is presented. Rossi X-ray timing explorer observation data is used for simulation, and the simulation result verifies the effectiveness of the suggested method.
Uniform finite-time stability of discrete-time switched descriptor systems
Authors: Gao Zai-Rui  , Shen Yan-Xia  , Ji Zhi-Cheng  ,   Key Laboratory of Advanced Process Control for Light Industry, Ministry of Education; Institute of Electrical Automation, Jiangnan University, Wuxi 214122, China
Published: December 2020

The problem of uniform finite-time stability for a class of discrete-time switched descriptor systems is considered. Firstly, the concept of finite-time stability for continuous descriptor systems is extended to discrete-time switched descriptor systems. Secondly, based on the Lyapunov-like function method, and under arbitrary switching signal, sufficient conditions under which discrete-time switched descriptor systems are regular and causal, the uniform finite-time is bounded and uniform finite-time is stable, are derived. Then, the state feedback controllers are designed to guarantee the discrete-time switched descriptor system uniform finite-time stablility. Finally, some numerical examples show that the results obtained in this paper are effective.
Optimizing quantum circuits using higher-dimensional Hilbert spaces
Authors: Liu Kai  , Li Wen-Dong  , Zhang Wen-Zhao  , Shi Peng  , Ren Chun-Nian  , Gu Yong-Jian  ,   Department of Physics, Ocean University of China, Qingdao 266100, China
Published: December 2020

Inspired by Lanyon (B. P. Lanyon et al. 2008 Nature Physics. 5 134) successfully simplifying the three-qubit Toffoli gate, we present a novel scheme that optimizes universal quantum logic circuits using assisted higher-dimensional Hilbert space. We construct a more efficient two-qubit circuit and a more effective three-qubit universal quantum circuit by using assisted dimension, Cosine-Sine Decomposition (CSD) and Quantum Shannon Decomposition (QSD). Meanwhile, we present the formula for the complexity of arbitrary n-qubit universal quantum gate. We propose the physical implementation of this scheme by linear optical circuits and cavity-QED. The results show that the two-qubit and three-qubit universal quantum circuits are respectively close and superior to the current optimal scheme in complexity. And with the increase of the number of qubits, the advantage of our scheme will become increasingly prominent.
Steady state characteries of FitzHugh-Nagumo neural system subjected to two different kinds of colored noises
Authors: Yang Ya-Qiang  , Wang Can-Jun  ,   Department of Mathematics, Baoji University of Arts and Sciences, Baoji 721013, China;,   Nonlinear Research Institute, Baoji University of Arts and Sciences, Baoji 721016, China
Published: December 2020

Making use of the unified colored noise approximation, the steady sate characteristics of the one-dimension of FitzHugh-Nagumo neural system with two different colored noises are investigated. The expressions of the steady state probability distribution function and the mean value are obtained. After numerical calculation, the results show that the self-correlated time of the multiplicative noise 1, the self-correlated time of the additive noise 2,the intensity of the additive noise , and the intensity of the multiplicative noise D can induce the transition. The increases of and D are conductive to the switch from the exciting state to the resting state. However, with 1 and 2 increasing, the switch from the resting state to the exciting state becomes obvious. The noise intensity and it self-correlated time play opposite roles.
Analysis the convergency speed of estimating the network topology based on the dynamical synchronization
Authors: Yang Pu  , Zheng Zhi-Gang  ,   Beijing-Hong Kong-Singapore Joint Center for Nonlinear and Complex Studies, Department of Physics, Beijing Normal University, Beijing, 100875, China
Published: December 2020

Identifying convergent speed is an important but rarely discussed problem in estimating topologies of complex networks. In this paper, we discuss this problem mainly in both weakly and strongly coupled conditions. In the weakly coupled conditions, the convergent speed we defined increases linearly with coupling strength increasing. After analyzing the dynamics, we find that this relation is universal. In light of the repeatedly driving method we proposed recently, we generalize the definition of the convergent speed into the area of synchronization. In this case, there is a best length of the driving time series to maximize the convergent speed. The knowledge of convergent speed helps us understand the topological information embedded in the time series.
Sparse and dense spiral waves in heterogeneous excitable media
Authors: Dong Li-Fang  , Bai Zhan-Guo  , He Ya-Feng  ,   College of Physics Science and Technology, Hebei University, Baoding 071002, China
Published: December 2020

Dynamic behaviors of sparse and dense spirals are investigated numerically based on a Barkley model in heterogeneous excitable media. It is found that the rotating frequency of sparse spiral wave decreases rapidly with b increasing and then tends to saturation, which is different from that of dense spiral wave. The period and wavelength of dense spiral wave increase with the increase of parameter or the size R of localized inhomogeneity, which depends more sensitively on the size R than those of sparse sprial wave. The change of the speed of dense spiral wave tip with R is opposite to that of the sparse spiral wave tip. In addition, inhomogeneous effect gives rise to a defect point in arm of each of the two spiral waves when or b increases above a critical value.
Complex networks from multivariate time series for characterizing nonlinear dynamics of two-phase flow patterns
Authors: Gao Zhong-Ke  , Jin Ning-De  , Yang Dan  , Zhai Lu-Sheng  , Du Meng  ,   School of Electrical Engineering & Automation, Tianjin University, Tianjin 300072, China
Published: December 2020

We use finite element analysis method to optimize and design a new curve half-ring conductance sensor for gas-liquid two-phase flow system. Then we carry out gas-liquid two-phase flow experiment in multiphase flow loop facility, and use the designed sensor to measure multivariate time series corresponding to different flow patterns. According to the measured signals, we construct complex networks from multivariate time series for different flow patterns by a network inference method. Through investigating the community structures of the constructed networks, we find that different communities correspond to different flow patterns and the network statistics in community can be used to effectively characterize the dynamic behavior of different flow patterns. In this regard, our method can be a powerful tool for identifying flow patterns and uncovering the nonlinear dynamics governing the evolution of different flow patterns.
Research on the real-time measurement system based on QEPAS
Authors: Wang Gui-Shi  , Yi Hong-Ming  , Cai Ting-Dong  , Wang Lei  , Tan Tu  , Zhang Wei-Jun  , Gao Xiao-Ming  ,   Laboratory of Environmental Spectroscopy, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China
Published: December 2020

A real-time measurement of gases based on QEPAS is introduced. For eliminating fluctuation of laser, a simple method, in which a digital PID algorithm and a software lock-in amplifier designed by using Lab-VIEW are employed, is utilized to lock the laser to the center of the absorption line. In order to test the system, an absorption line of water vapor near 1.396 m is chosen by using a fiber-coupled distributed feedback (DFB) diode laser. An over-40-hours continuous measurement is implemented, and the relevant results are presented and discussed. The detection limit of the system is 1 ppm. This method can also be used to measure the trace gases and monitor the industry gases.
Numerical simulation and study of three-dimensional thermal field emission
Authors: Peng Kai  , Liu Da-Gang  ,   School of Physical Electronics, University of Eelectronic Science and Technology of China, Chengdu 610054, China
Published: December 2020

In this paper, we study the basic theory of field emission, thermionic emission and the thermal field emission, derive their current density formula, the initial distribution of the particles and their initial momentum. And then we achieve a field emission model, thermionic emission model and thermal field emission model on the basis of FDTD-PIC algorithm software. Finally, we verify its correctness using a wedge-shaped-cathode device.
Isolated intense sub-30-as pulse generation by quantum path control in the three-color laser pulse
Authors: Chen Ji-Gen  , Zeng Si-Liang  , Yang Yu-Jun  , Cheng Chao  ,   Department of Physics and Materials Engineering, College of Physics and Electronic Engineering, Taizhou University, Taizhou 318000, China;,   Science and technology computation physics laboratory, Institute of Applied Physics and Computational Mathematics, Beijing 100088, China;,   Institute of Atomic and Molecular Physics, Jilin University, Changchun 130012, China
Published: December 2020

We theoretically investigate the high-order harmonic generation from He+in the two-color laser pulse, which is composed of a multi-cycle 800 nm laser and 1600 nm laser. Compared with the case of the fundamental laser, the harmonic spectrum presents a two-plateau structure, and a broadband supercontinuum appears in the second plateau, of which the efficiency is approximately 2 orders of magnitude lower than that of the first plateau. Adding the 27th harmonic pulse to the two-color laser at a proper time, we can control the ionization mostly occurring at half the optical cycle, and the short quantum path can be picked out, the second plateau is heightened four orders of magnitude compared with the case of the two-color case. Furthermore, the supercontinuum spectrum is extended from the second plateau to the first one. An intense isolated pulse with a duration of 29 as is obtained by superposing the 190th285th harmonics in the continuous region.
Fast parallel iterative calculating of the composite scattering between targets and rough surface
Authors: Wang Xiao-Bing  , Liang Zi-Chang  , Wu Zhen-Sen  ,   School of Science, Xidian University, Xi'an 710071, China;,   The State Key-Lab for Electromagnetic Characters of Environment, Shanghai 200438, China
Published: December 2020

A new fast far field approximation algorithm is introduced to calculate the composite scattering characteristics of rough surface and the target in near field, by using the reduced-order electromagnetic current iteration method. Also we use the multi-process parallel algorithm to reduce the simulation time and analyze the influence on the results of the reduced-order electromagnetic current iteration. The calculated results by the algorithm described in the paper and the results obtained by multi-level fast multi-pole method (MLFMM) are in good agreement, so the effectiveness of the algorithm is verified. At the same time, the use of tank to carry out the measurements of near-field complex scattering between the targets and rough surfaceshows that the test results and the calculation results are very consistent.
Simulation for Space target interference imaging system distorted by atmospheric turbulence
Authors: Liu Yang-Yang  , Zhang Wen-Xi  ,   Academy of Opto-electronics, Chinese Academy of Sciences, Beijing 100094, China
Published: December 2020

Interference imaging system for space target has close relation with atmospheric environment, and atmospheric turbulence disturbance distorts terribly the wavefront phase of any transported optics launched from any optics system. In the space target interference imaging system the phase-closure-principle is adopted, in order to eliminate possible effects of atmospheric turbulence on the target image. Based on the power spectrum method and the Fourier transform method, the numerical simulation of wavefront phase screen, which is distorted by atmospheric turbulence conforming to the statistical rules of kolmogonov model and modified Von Karmen model, is respectively implemented. Various images by several different phase-screen models on the interference imaging system are obtained. Simulation results show that, with the advantage of adopting phase-closure-principle, the possible effects of atmospheric turbulence imaging can be eliminated basically.
The dynamic effect of a field with a time-varying frequency on the atom-atom entanglement in a double J-C model
Authors: Cui Cong-Cong  , Xie Shuang-Yuan  , Yang Ya-Ping  ,   Department of Physics, Tongji University, Shanghai 200092, China
Published: December 2020

The entanglement between the two atoms of two separate Jaynes-Commings models is investigated by means of the concurrence. We restrict our attention to two cases, the field frequency varying with time in the forms of sine and rectangle. When the field frequency varies with time in the form of sine, the period and the amplitude of the atom-atom concurrence will decrease as the amplitude of the sine frequency modulation increases. Not only the sine field frequency modulation but also the rectangular field frequency modulation can affect the interaction of the field with atom between resonance and off-resonance. The field frequency modulation can also affect the atom-atom entanglement. The suitable field frequency modulation is favorable for improving, enhancing and stabilizing the degree of the atom-atom entanglement. The suitable field frequency modulation can also prevent the atom-atom entanglement from entanglement sudden death and control it dynamically.
Focusing properties of the high order vector beam by a high numerical aperture lens
Authors: Wang Zheng  , Gao Chun-Qing  , Xin Jing-Tao  ,   School of Optoelectronics, Beijing Institute of Technology, Beijing 100081, China
Published: December 2020

The intensity distribution of the -2 to 4-order vector Bessel beams in the focal planes of a high numerical aperture lens are simulated based on the Richards-Wolf's vector diffraction integral model, and the distribution of gradient force capturing a glass ball in vacuum is also simulated. The simulated results show that the patterns, the areas of the focused light field and the variation of components are closely related to the order of the vector beams. Additionally, the distribution of the focused light field gradient force is closely related to the order of the vector beams, which can form optical traps with different shapes and scales.
Coherence properties of the supercontinuum generated in anomalous dispersion region of photonic crystal fibers
Authors: Jin Ai-Jun  , Wang Ze-Feng  , Hou Jing  , Guo Liang  , Jiang Zong-Fu  ,   College of Optoelectronic Science and Engineering, National University of Defense Technology, Changsha 410073, China
Published: December 2020

We numerically calculated the coherence properties of the supercontinuum based on the definition of complex degree of mutual coherence, and obtained the spectral broadening of the pump pulse and the coherence properties of the generated supercontinuum under different pump powers. The results showed that the dominant underlying mechanisms of the spectral broadening are soliton self-frequency shift and dispersive wave generation when the pump wavelength located in the anomalous dispersion region of photonic crystal fiber. While the coherence properties are affected by the modulation instability which amplifies the stochastic noise of the pump pulse, thus the generated frequency components have stochastic phases and amplitudes, which induces the degradation of the coherence of the supercontinuum. The gain of modulation instability increases with the increasing of the pump power, and the effect of the noise on the supercontinuum will become greater which degrades the coherence properties. Low pump power is required to obtain high coherent supercontinuum, and suitable pump power should be adjusted to get wide bandwidth and high coherent supercontinuum.
Near-field modulated simulation of repaired site contained crack or bubble in fused silica subsurface
Authors: Zhang Chun-Lai  , Liu Chun-Ming  , Xiang Xia  , Dai Wei  , Wang Zhi-Guo  , Li Li  , Yuan Xiao-Dong  , He Shao-Bo  , Zu Xiao-Tao  ,   School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054, China;,   Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 629100, China
Published: December 2020

Three-dimensional (3D) model of Gaussian repaired site contained crack or bubble is establishd, and 3D finite-difference time-domain method is used to simulate near-field modulation of 355 nm laser incidence by those defects on fused silica rear-surface. The results show that we should avoid any unrepaired cracks, especially cracks with incident angle of 65°, and the size of bubbles should be less than 5 λ. All of above contribute to weaken the modulation around repaired pit. When crack or bubble distributes in the near-surface area (<3 λ) and close to the edge of pit ring, the field modulation is obvious. With the increase of lateral gap, there will be a maximum due to electric field fluctuations near the surface area, especially when cracks are contained. And the electric field gradually stabilized when lateral gap is far from the surface. As the vertical gap increases, the number of large electric field decreases, and stabilized oscillation emerges when vertical gap is larger than 3 λ. If cracks or bubbles are located below Gauss repaired sites within a few wavelengths, its depth seems to be enlarged under irradiation.