bluuebunny/crossref_metadata_2025 huggingface dataset:
Epidemic spreading on scale-free networks with traffic flow
Authors: Qiu Shen-Wei  , Wang Kai  , Liu Qian  , Pei Wen-Jiang  , Hu Hen-Kai  , Yang Guang  , Wei Cheng-Jian  , Zhang Yi-Feng  ,   College of Electronic and Information Engineering, Nanjing University of Technology, Nanjing 210009, China;,   Department of Radio Engineering, Southeast University, Nanjing 210096, China
Published: December 2020

The infectivity of a node is determined by its actual betweenness bk in the epidemic model based on traffic-flow other than degree k which is different from the classical epidemic models. Utilizing the mean-field theory, we propose a modified SIS epidemic model based on traffic-flow. With this model, taking MIP route as an example, we re-study the relationship among spreading probability β, traffic generation rate λ, epidemic threshold βc, the stationary density of infected nodes ρ. Both theoretical analysis and experimental results show that βc is the ratio of the mean of the actual betweenness bk > to its mean square bk2 >, when network topology and route strategy are given. Moreover, the stationary density of infected notes ρ behaves as power-law exponent with the reciprocal of the product of the spreading probability β , the traffic generation rate λ and the mean of the actual betweenness bλ=1 >.
Entanglement properties in the system of atoms interacting with three coupled cavities
Authors: Lu Dao-Ming  ,   Department of Electronic Engineering, Wuyi University, Wuyishan 354300, China
Published: December 2020

The entanglement dynamics of the system composed of three two-level atoms resonantly interacting with three coupled cavities is investigated in this paper. The influence of coupling constant between cavities on the entanglement between atoms and that between cavities are discussed. The results obtained using the numerical method show that the entanglement between atoms has a nonlinear relation with increase of the cavity-cavity coupling coefficient. On the other hand, the entanglement between cavity A and cavity B and the entanglement between cavity B and cavity C weaken with the increase of the coupling constant between cavities, but the entanglement between cavity A and cavity C strengthens with the increase of cavity-cavity coupling coefficient.
Dynamical analysis of linear SDOF oscillator with fractional-order derivative (Ⅱ)
Authors: Shen Yong-Jun  , Yang Shao-Pu  , Xing Hai-Jun  ,   Department of Mechanical Engineering, Shijiazhuang Tiedao University, Shijiazhuang 050043, China
Published: December 2020

A linear single degree-of-freedom (SDOF) oscillator with two kinds of fractional-order derivatives is investigated by the averaging method, and the approximately analytical solution is obtained. The effects of the parameters on the dynamical properties, including the fractional coefficients and the fractional orders in the two kinds of fractional-order derivatives, are characterized by the equivalent linear damping coefficient and the equivalent linear stiffness, and the results is entirely different from the results given in the existing literature. A comparison of the analytical solution with the numerical results is made, and their satisfactory agreement verifies the correctness of the approximately analytical results. The following analysis of the effects of the fractional parameters on the amplitude-frequency is presented, and it is found that the fractional coefficients and the fractional orders can affect not only the resonance amplitude through the equivalent linear damping coefficient, but also the resonance frequency by the equivalent linear stiffness. Finally, the effects of the fractional coefficient in the second fractional-order derivative on resonance frequency are analyzed, and the design rule for the fractional coefficient in the second fractional-order derivative to meet the satisfactory vibration control performance is pointed out.
Chaotic property analysis of pressure fluctuation for oxygen phase change heat exchanger
Authors: Liu Dan-Yang  , Wang Ya-Wei  , Wang Xian  , He Kun  , Zhang Xing-Juan  , Yang Chun-Xin  ,   Department of Aeronautic Science and Engineering, Beihang University, Beijing 100191, China;,   Beijing Aerospace Propulsion Institute, Beijing 100076, China
Published: December 2020

Pressure fluctuation signals at the inlet/outlet of an oxygen phase-change heat exchanger are analyzed using non-linear method. Chaotic characteristic parameters such as correlation dimension, Kolomogrov entropy and the largest singular value decomposition (SVD) for the covariance matrix of an established 10-dimensional phase space are analyzed. Results prove that the heat exchanger is a non-linear system with chaotic characteristics. Correlations between these parameters and Prantl Number are also examined for the thermal behavior of oxygen in the critical region. The strong dependence of these characteristic parameters on Pr indicates that they can be used to investigate effectively the phase change behavior of pure substance.
Research on the dynamics of opinion spread based on social network services
Authors: Xiong Xi  , Hu Yong  ,   Institute of Information Security, Sichuan University, Chengdu 610065, China
Published: December 2020

Social network services and microblog are important application modes of Web2.0, in which opinion spread is quite different from that in other cyber-media and in traditional media. In this paper, we present an opinion-spreading model based on online social network services, to study the forms and features of the spread of public opinion in social network services. The simulation results show that the model can fit the actual data from a social network site. The speed of information spread is consistent with the conclusion of six degrees of separation theory. When an opinion with strong tendency spreads in a network in which intrinsic views obey uniform distribution, the opposite view cannot exist in the stable network. In a stable network, view distribution is related to the degree of source node and the depth of backtrack, but not related to confidence limit, which is different from Deffuant model and Hegselmann-Krause model. Meanwhile, in this paper, we the also analyze the influence of the probability of spreading will, the probability of opinion change and confidence limit on relaxation time. Finally, in the paper are shown two applications of the model: the spread of rumors and the role of opinion leaders.
Molecular structure and electronic spectrum of pentachlorophenol in the external electric field
Authors: Du Jian-Bin  , Tang Yan-Lin  , Long Zhen-Wen  ,   Laboratory for Photoelectic Technology and Application, Guizhou University, Department of Phisics, Guizhou University, Guiyang 550025, China
Published: December 2020

In order to study the influence of external electrical field on molecular structure, chemical bond and electronic spectrum of environmental poison chlorophenol, the method B3LYP of the density functional theory (DFT) at 6-311++G(d, p) level is used to calculate geometrical parameters, dipole moments and total energies of the ground state of pentachlorophenol molecule under different external electric fields (from 0 to 0.025 a.u.) in this article. On this basis, the UV absorption spectra of pentachlorophenol (PCP) are studied using the time-dependent density functional theory (TDDFT) in the same fundamental group and compared with the ultraviolet absorption peak of phenol given in the literature. Finally, the rules of external electric field influencing wavelengths and oscillator strengths of the first ten excited states of a PCP molecule are studied. The results show that molecular geometry is strongly dependent on the field intensity, the molecular dipole moment is proved to be first decreasing, then increasing and the total energy first increasing then decreasing with the increase of the field intensity. Compared with the ultraviolet absorption peak of phenol, that of PCP is red-shifted. The oscillator strength of excited state of PCP is proved to be decreasing, and the ultraviolet absorption peak is also red-shifted with the increase of the field intensity.
Investigation of the doping failure induced by DB in the SiNWs using first principles method
Authors: Liang Pei  , Liu Yang  , Wang Le  , Wu Ke  , Dong Qian-Min  , Li Xiao-Yan  ,   College of Optical and Electronic Technology, China Jiliang University, Hangzhou 310018, China;,   Faculty of Engineering, Zhejiang University, Hangzhou 310027, China
Published: December 2020

First-principles calculations are employed to investigate total energies and electronic structures of the B/N doped silicon nanowires, the B/N doped silicon nanowires with and without dangling bond (DB). And the calculation indicates that the DB would lead to the doping failure. Band-structure calculations indicate that B/N doped silicon nanowires without dangling bond show regular p/n type of the charge carrier, while the dangling bond would cause signal atom doping failure, which is not due to the transfer of electrons, but results from the capturing of the electron (hole) by the defect energy level induced by the surface dangling bond. Moreover, the small molecule adsorption can reactivate impurities doping p/n characteristics. The reactivation mechanism is not the transfer of the electrons, thus it can hold the doping characteristics.
Characterization of defects and research on impulse aging in ZnO varistor ceramics
Authors: Zhao Xue-Tong  , Li Jian-Ying  , Li Xuan  , Li Sheng-Tao  ,   State Key Laboratory of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, Xi'an 710049, China
Published: December 2020

The electrical and dielectric properties and the microstructures of a polynary ZnO-based varistor ceramics with 14000 times impulse current aging test are measured. The relationship between defect structure and impulse current aging is mainly investigated. It is found that the electrical properties decrease rapidly with impulse aging and the dimensional effect of ZnO varistor ceramics is dominated not only by grain but also by grain boundary. Additionally, four defect relaxations are found at different temperatures by using dielectric spectra. Two defect relaxations appearing below -60 ℃ with activation energies about 0.24 eV and 0.35 eV are identified to be intrinsic defects originating from interstitial Zn L(Zni··) and vacancy oxygen L(VO·), which are not affected by impulse current aging. Other two relaxations appearing above 80 °C are suggested to be extrinsic defects originating from trap levels L(ingr) at intergranular phase and trap levels L(gb) at grain-boundary interfaces, respectively. Only L(gb) decreases from 0.84 eV to 0.76 eV due to impulse current aging while other trap levels keep unchanged. It is further proposed that L(gb) is responsible mainly for the electrical property and stability of ZnO ceramics.
Generation of the array of optical traps by liquid crystal spatial light modulator
Authors: Gu Song-Bo  , Xu Shu-Wu  , Lu Jun-Fa  , Ji Xian-Ming  , Yin Jian-Ping  ,   Science College, Nantong University, Nantong 226007, China;,   State Key Laboratory of Precision Spectroscopy, Department of Physics, East China Normal University, Shanghai 200062, China;,   Department of Physics, East China Institute of Technology, Fuzhou 344000, China
Published: December 2020

Liquid crystal spatial light modulator (LC-SLM) can be readily used to fabricate the diffractive optical elements. However, a disadvantage of the finite resolution always exists in LC-SLM. In this paper, a new scheme of fabricating phase grating with LC-SLM is proposed to produce one-dimensional (1D) and two-dimensional (2D) array of optical traps. The advantage of the LC-SLM is fully utilized and the disadvantage is well avoided in our scheme. The phase distribution of the grating is optimized by using iterative Fourier series expansion. The grating is designed by simulation according to the LC-SLM technique parameters, and the corresponding light intensity distribution is calculated. The results show that the array has very high peak value intensity and big gradient of intensity by illuminating the grating with a large detuning and low power laser. The optical dipole potential of trapping cold atoms achieves the order of mK, and the interaction force between atom and optical field is much greater than the atom gravity.
Effect of dust particle potential on plasma conductivity
Authors: Chen Yun-Yun  , Zheng Gai-Ge  , Gu Fang  , Li Zhen-Hua  ,   School of Physics and Optoelectronic Engineering, Nanjing University of Information Science and Technology, Nanjing 210044, China;,   Department of Information Physics and Engineering, Nanjing University of Science and Technology, Nanjing 210094, China
Published: December 2020

In this paper, the concept of electrical potential influencing factor is proposed to describe the effect of electrical potential difference between the dust particle and background plasma on conductivity, based on which the conductivity model of dusty plasma is improved. The electrical potential influencing factor is directly proportional to the charge number, number density, radius of the dust particle, and the electron number density of the background plasma. Meanwhile, it is inversely proportional to the electron temperature of the background plasma. Taking rocket exhaust plume for example, the conductivities with and without considering potential difference are given both in the microwave and near infrared regions. In the given dusty plasma parameters condition, the influence of electrical potential difference on electrical conductivity reduces as the incident frequency increases. When the frequency increases to the near-infrared light region, the influence of electrical potential difference on the imaginary part of the conductivity can be ignored.
A scanning filtering method for enhancing the signal-to-noise ratio of chirped laser pulse
Authors: Zeng Bing  , Zeng Shu-Guang  , Zhang Bin  , Sun Nian-Chun  , Sui Zhan  ,   College of Electronics and Information Engineering, Sichuan University, Chengdu 610064, China;,   Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

Based on the principle of scanning filtering, a new optical scanning filtering method for improving signal-to-noise ratio(SNR) of the chirped pulse is proposed. For the scanning filtering scheme of Fabry-Perot (F-P) etalon including an electro-optic crystal, the spectral characteristics of the scanning filter are analyzed quantitatively. Furthermore, the effects of the reflectivity of the parallel-plates of F-P etalon and the types of the electro-optic crystals on the output SNR are discussed in detail, and the influence of the variation of the controlling voltage applied to the electro-optic crystal on the filtering effect is also studied. The results show that the narrower the bandwidth of scanning filter transmission window is, the better the improved SNR will be. In order to ensure the filtering effect, the reflectivity of the parallel-plates of F-P etalon should be more than 0.9. Compared with the scheme of scanning filter built-in ordinary linear electro-optic crystal, the scheme of F-P etalon including an secondary standard electro-optic crystal, i.e., KTa1-xNbxO3 crystal, requires a low voltage, and it is easy to control. The differences of KTa1-xNbxO3 crystal components have little influence on the filtering effect, whereas the variations of controlling voltage and chirp rate of the signal exhibit a greater influence on the filtering effect.
The analytical solution and stability of multipole surface soliton in nonlocal nonlinear medium
Authors: Cai Shan-Yong  , Mei Lei  , Peng Hu-Qing  , Lu Da-Quan  , Hu Wei  ,   Laboratory of Photonic Information Technology, South China Normal University, Guangzhou 510631, China
Published: December 2020

In this paper, the research on the multipole surface soliton in nonlocal nonlinear medium is done. Theoretical study indicates that multipole surface soliton in nonlocal nonlinear medium can also be regarded as a half part of a bulk soliton with an antisymmetric amplitude distribution. Using this fact, we could obtain the analytical solution of multipole surface soliton easily. Secondly, comparing the numerical solution acquired by numerical computation with analytical solution, we find that analytical solution is in good agreement with numerical solution. Finally, a research is done on the stability of multipole surface soliton using our model. The result shows that the width of the instability domain of dipole surface soliton is smaller than that of quadrupole bulk soliton. In addition all higher-order multipole surface solitons are unstable.
Compositional dependence of crystallization behavior in GeS2-Ga2S3-CsI chalcogenide glass
Authors: Lin Chang-Gui  , Li Zhuo-Bin  , Qian Hai-Jiao  , Ni Wen-Hao  , Li Yan-Ying  , Dai Shi-Xun  ,   College of Materials Science & Chemical Engineering, Ningbo University, Ningbo 315201, China;,   Laboratory of Infrared Materials and Devices, Ningbo University, Ningbo 315211, China
Published: December 2020

Controllable precipitation of crystals is one of the key points in the fabrication of chalcogenide glass-ceramics. Glass compositions of 65GeS225Ga2S310CsI (GGC25) and 70GeS220Ga2S310CsI (GGC20) are specifically selected, and their glass-ceramic samples are obtained by careful heat treatment. The transmission spectra, grain sizes, and crystal phases of obtained samples are characterized using visible-near IR spectroscopy, SEM, XRD, and Raman scattering. Different crystallization behaviors are evidenced that GeS2 crystals are precipitated in GGC20 glass, and GGC25 samples show two crystallization mechanisms during the heat treatment, that is, Ga2S3 crystals were first precipitated and then the GeS2 ones. The compositional and the microstructural dependences of crystallization behavior are discussed, which would be a significant reference for the controllable crystallization in chalcogenide glasses.
Study on TE0n nonuniform ripple-wall mode converter in circular waveguide
Authors: Lan Feng  , Yang Zi-Qiang  , Shi Zong-Jun  ,   Research Institute of High Energy Electronics, University of Electronic Science and Technology of China, Chengdu 610054, China
Published: December 2020

In this paper, we present an optimal design of TE0n nonuniform ripple-wall mode converter in circular waveguide. The research work is based on the general coupled wave theory and numerical optimization method. The results of numerical calculation are in good agreement with those of simulation by HFSS. Compared with traditional TE0n mode converter of periodic waveguide perturbations, the TE0n nonuniform ripple-wall mode converter can achieve a high mode conversion efficiency with less corrugated periods. The length of the converter is shortened nearly by a half and the operating bandwidth with over 95% mode conversion is increased by 150%. The research work provides an important theoretical reference and a physics model for designing high power gyrotron mode converter with small axial size, wide operating bandwidth and high conversion efficiency.
Theoretical and experimental studies of electromagnetic wave transmission in plasma
Authors: Zheng Ling  , Zhao Qing  , Luo Xian-Gang  , Ma Ping  , Liu Shu-Zhang  , Huang Cheng  , Xing Xiao-Jun  , Zhang Chun-Yan  , Chen Xu-Lin  ,   School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054, China;,   State Key Laboratory of Optical Technologies for Microfabrication, Institute of Optics and Electronics, Chinese Academy of Sciences, Chengdu 610209, China
Published: December 2020

The aircrafts, such as space shuttle, spaceship and so on, are facing the well-known blackout problem when they reentry into the atmosphere. The plasma sheath leads electromagnetic waves to attenuation, and the communications between the aircrafts and the ground to losing, and even completely interrupte, thereby resulting in the loss of radar targets and threatening the lives of the astronauts. Therefore, it is important to study the properties of the electromagnetic wave transmission in plasma. The characteristics of electromagnetic wave transmission in plasma are studied theoretically and experimentally in this paper. The variations of the electromagnetic wave attenuation with plasma density, collision frequency and electromagnetic wave frequency are obtained. The electromagnetic wave attenuation increasean an order of magnitude with plasma density increasing an order of magnitude. The electromagnetic wave attenuation first increases and then decreases with plasma collision frequency increasing, the electromagnetic wave attenuation decreases with the increase of electromagnetic wave frequency. The electromagnetic wave transmission properties in plasma are studied experimentally with shock tube, and the experimental results accord well with the theoretical results. The results show that increasing the electromagnetic wave frequency is an effective way to solve the reentry blackout problem.
The influence of surface polarization on the saturation behaviour of a weak anchoring NLC cell
Authors: Guan Rong-Hua  ,   School of Sciences, North China Electric Power University, Baoding 071003, China
Published: December 2020

Based on the modified Rapini-Papoular formula for surface anchoring energy, the saturation behaviour of a weak anchoring nematic liquid crystal cell is studied. The mathematical equations of solving director distribution are obtained. A parameter reflecting the characteristic of director distribution is introduced. Expressions for saturation voltage and the parameter reflecting the characteristic of director distribution are obtained for the second order transition. The methods of calculating the two quantities for the first order transition are also given. The influences of surface polarization on the two quantities are discussed in detail. The results show that whether the second or the first order transition, the position of the maximal tilt angle of director will shift towards the substrates with the increase of surface polarization. The influences of surface polarization on saturation voltage for the second and the first order are reverse. The saturation voltage will increase for the second order but decrease for the first order with the increase of surface polarization.
Magnetic properties of CoxZn1-xO by solid-state reaction
Authors: Wang Feng  , Wang Yue-Yan  , Huang Wei-Wei  , Zhang Xiao-Ting  , Li Shan-Yu  ,   Physics and Information Engineering School, Quanzhou Normal University, Quanzhou 362000, China
Published: December 2020

Co doped ZnO powders and tablets are synthesized by the solid-state reaction. The X-ray diffraction experimental results indicate that Zn2+ ions are substituted by Co2+ ions. All samples are paramagnetic at room temperature. Using density functional theory (DFT+U) method, the calculated results indicate that the antiferromagnetic ground state of Co2Zn14O16 system is more stable. By calculating the electronic transfers of Co and O atoms, it is indicated that the mechanism of the magnetism tends to the indirect exchange model of Co2+O2-Co2+ bonding in CoZnO system. The direct exchange formula Jpd of Anderson model is modified. Two possible ways to achieve the intrinsic ferromagnetic oxide semiconductor are putted forward.
Calcium ion spiral wave induced by random calcium ion sparks in single heart cell
Authors: Bai Yong-Qiang  , Zhu Xing  ,   School of Electronic Science, Northeast Petroleum University, The University-enterprise R & D Center of Measuring and Testing Technology & Instrument and Meter Engineering in Heilongjiang Province, Daqing 163318, China;,   School of Physics, State Key Laboratory for Artificial Microstructure and Mesoscopic Physics, Peking University, Beijing 100871, China;,   National Center for Nanoscience and Technology, Beijing 100080, China
Published: December 2020

Calcium ion spiral wave induced by random released calcium ion sparks in single heart cell is studied using the improved discrete fire-diffuse-fire model and phase analysis method. The results show that calcium ion spiral wave can be excited in resting heart cell by calcium ion sparks at an appropriate release frequency. The key of the generation of calcium ion spiral wave is the emergence of the phase singularity caused by the calcium sparks in the different time and space sequences. The number of phase singularity is exponentially linked with calcium ion spark frequency, and has the limit in a fixed system.
Dynamic stochastic shortest path algorithm
Authors: Zhang Shui-Jian  , Liu Xue-Jun  , Yang Yang  ,   Key Laboratory of Virtual Geographic Environment of Ministry of Education, Nanjing Normal University, Nanjing 210046, China
Published: December 2020

The static shortest path problem has been solved well. However, in reality, more networks are dynamic and stochastic. The states and costs of network arcs and nodes are not only uncertain but also correlated with each other, and the costs of the arcs and nodes are subject to a certain probability distribution. Therefore, it is more general to model the shortest path problem as a dynamic and stochastic optimization problem. In this paper, the dynamic and stochastic characteristics of network nodes and arcs and the correlation between the nodes and arcs are analyzed. The dynamic stochastic shortest path is determined. The dynamic stochastic optimization model of shortest path is provided, and a shortest path genetic algorithm is proposed to solve dynamic and stochastic shortest path problem. The effective and reasonable genetic operators are designed according to the topological characteristics of the network. The experimental results show that this algorithm can be used to effectively solve the dynamic stochastic shortest path problem. The proposed model and algorithm can be applied to the network flow optimization problem in transportation, communication networks, etc.
Research on electromagnetic scattering computation and synthetic aperture radar imaging of ship located on two-dimensional ocean surface
Authors: Ji Wei-Jie  , Tong Chuang-Ming  ,   Missile Institute Air, Force Engineering University, Sanyuan 713800, China;,   State Key Laboratory of Millimeter Waves, Nanjing 210096, China
Published: December 2020

The electromagnetic (EM) scattering computation and the synthetic aperture radar (SAR) imaging of three-dimensional conductor object located on ocean surface are studied. The EM scatterings of object, ocean surface and the interaction between them are computed based on the geometric optic, the physical optic, the shooting and bouncing ray. The method of equivalent current is used to calculate the diffraction by object edges. The shadowing effect is also included, and the tapered incident wave is chosen to reduce the truncation error. The Pierson-Moskowitz random sea surface is generated by using Monte-Carlo method, and numerical results are provided to validate the approach through the computation of radar cross section for cube and ship objects located on ocean surface. The backscattering electric field data of different frequencies and angles are computed quickly by using this approximate method. Combining the backscattering data and SAR images technology, the images of cube and ship located on ocean surface are obtained. The method introduced in this paper has important theoretical significance in realistic ocean remote sensing and detection of military targets located on ocean surface.
Theory and experiment research on a Piecewise-linear model based on stochastic resonance
Authors: Wang Lin-Ze  , Zhao Wen-Li  , Chen Xuan  ,   Institute of Computer Application Technology, School of Computer Science and Technology, Hangzhou Dianzi University, Hangzhou 310018, China;,   School of Mechanical Engineering, Hangzhou Dianzi University, Hangzhou 310018, China
Published: December 2020

We propose a new piecewise-linear model. The principle of stochastic resonance in the new piecewise-linear model is introduced, and the formula of the signal-to-noise ratio (SNR) is deduced. It is proved that stochastic resonance characteristics can be utilized to realize the conversion of noise energy into periodic signal energy. The results clearly show the enhancement of the SNR of the output signal. The model characteristic that the weak periodic signal can be detected from noise background is investigated by the numerical simulation. The stochastic resonance system based on the model is built by using a circuit. The behaviors of stochastic resonance are studied when the circuit is driven by noise and period signal. The simulation and experimental results show that the model can effectively detect weak periodic signal, and enhance the SNR prominently.
Small target detection in the background of sea clutter using fractal method
Authors: Xing Hong-Yan  , Gong Ping  , Xu Wei  ,   Jiangsu Key Laboratory of Meteorological Observation and Information Processing, Nanjing University of Information Science and Technology, Nanjing 210044, China;,   College of Electronic and Information Engineering, Nanjing University of Information Science and Technology, Nanjing 210044, China
Published: December 2020

Because the detecting of the small target in the background of sea clutter is strongly dependent on sea condition, in this article we use fractional Brownian motion to model IPIX sea clutter and combine multifractal detrended fluctuation analysis (MF-DFA) to determine the fractal parameters for analyzing fractal and multifractal property of IPIX sea clutter. Based on the fact that Hurst parameter and fractal dimension can reflect the fractal property of data, a new parameter named fractal differential which has difference when the sea clutter with or without target is defined, thereby solving the problem of small target in sea clutter background. By comparing the multifractal parameters of two sea clutter, the experimental results show that H(q) is a special value which is bigger than zero when the sea clutter has a small target but smaller than zero when the sea clutter has no target if q is bigger than ten. Another method is proposed by using the difference of H(q). Two methods in this article can solve the problem of strong dependence of detecting the small target in different sea conditions on sea condition.
Adaptive synchronization of a class of fractional-order chaotic systems
Authors: Ma Tie-Dong  , Jiang Wei-Bo  , Fu Jie  , Chai Yi  , Chen Li-Ping  , Xue Fang-Zheng  ,   College of Automation, Chongqing University, Chongqing 400044, China;,   Key Laboratory of Optoelectronic Technology and System, Ministry of Education, College of Optoelectronic Engineering, Chongqing University, Chongqing 400044, China
Published: December 2020

In view of chaos synchronization of a class of fractional-order chaotic systems, a novel adaptive controller and adaptive updating law are designed based on the quasi-Lyapunov stability theory for fractional-order systems. The derived method has some advantages such as simple structure, low control cost and high generality compared with the existing results. Furthermore, the method can be applied to most typical fractional-order chaotic systems. Finally, numerical simulations are used to illustrate the effectiveness of the proposed synchronization method.
Studies on the optimization of terahertz emission based on the field ionization current model
Authors: Zhang Kai-Yun  , Du Hai-Wei  , Chen Min  , Sheng Zheng-Ming  ,   Key Laboratory of Laser Plasma of the Education Ministry, Department of Physics, Shanghai Jiao Tong University, Shanghai 200240, China;,   Lawrence Berkeley National Laboratory, California 94720, USA
Published: December 2020

Based on the theoretical model of field ionization current for terahertz (THz) emission in laser-gas interaction, the parameter optimization for strong THz emission via the two-color laser scheme is explored. It is found from numerical calculation that the ionization current is due mainly to the first-order ionization process and the contribution from high-order ionization is ignorable. In order to produce stronger THz emission, the ionization current can be enhanced by adjusting the amplitude ratio between the fundamental and its second harmonic laser pulses as well as their relative phase difference. The ionization current can also be increased by use of laser pulses at mid-infrared and by changing the gas species. Under the same laser pulse and gas density conditions, the ionization current from the Helium gas is almost twice that from the Neon gas.
Wavelet transform of coherent state
Authors: Yu Hai-Jun  , Du Jian-Ming  , Zhang Xiu-Lan  ,   Department of Physics, Huainan Normal University, Huainan 232001, China
Published: December 2020

Two new mother wavelets are constructed on the basis of the quantum mechanics of classical wavelet transform. Based on that, the wavelet transform of coherent state and particle number state is studied with the technique of integration within an ordered product, and the wavelet transform from coherent state to particle number state is obtained by numerical calculation.
Optical polarization rotation in a rubidium vapor
Authors: Cao Ming-Tao  , Qiu Shu-Wei  , Guo Wen-Ge  , Liu Tao  , Han Liang  , Liu Hao  , Zhang Pei  , Zhang Shou-Gang  , Gao Hong  , Li Fu-Li  ,   Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter of Ministry of Education, Xi'an Jiaotong University, Xi'an 710049, China;,   Key Laboratory for Electricity Gas and Oil Logging of Ministry of Education, Xi'an Shiyou University, Xi'an 710065, China;,   Key Laboratory for Time and Frequency Primary Standard of Chinese Academy of Sciences, National Time Service Center, Xi'an 710600, China
Published: December 2020

We theoretically and experimentally study the effects of Faraday rotation, optical polarization of self-rotation, and their overlapping rotation. In our theoretical simulation, we set up a simple and effective theoretical model for the three kinds of rotations. In our experiment, the atomic vapor is placed in a magnetic shielding cavity to shield the earth magnetic field. Doppler-free spectrum configuration is used and the F=2 F'=3 transition of 87Rb D2 line is chosen. We observe the three kinds of rotations, separately. Experimental results and theoretical simulations are in good agreement.
Effective radius of curvature of truncated laser beams with amplitude modulation and phase fluctuation
Authors: Shao Xiao-Li  , Ji Xiao-Ling  ,   Department of Physics, Sichuan Normal University, Chengdu 610068, China
Published: December 2020

Usually, high-power laser beams are amplitude modulated and have phase fluctuations (PFs). The analytic formula of the effective radius R of curvature of truncated laser beams with amplitude modulations (AMs) and PFs propagating through atmospheric turbulence is derived by using the statistical optics method. It is shown that the R in free space increases with the increases of the phase fluctuation parameter, the intensity modulation parameter and the truncated parameter. And the influence of turbulence on the R also increases with the increases of the three parameters. Furthermore, the R of Gaussian beams is largest in free space, but it is most affected by turbulence. Therefore, in turbulence the R of truncated laser beams with AMs and PFs is even larger than that of Gaussian beams when the propagation distance is large enough. In particular, the relative effective radius Rr of curvature varies non-monotonically with propagation distance, and there exists a minimum at a propagation distance where the influence of turbulence on the R is largest. In addition, the position where the Rr reaches its minimum increases with the increasees of intensity modulation and phase fluctuation.
Magneto-optical Faraday rotation effect enhancement of a thick metal Ag
Authors: Dong Li-Juan  , Du Gui-Qiang  , Yang Cheng-Quan  , Shi Yun-Long  ,   Institute of Solid State Physics, Shanxi Datong University, Datong 037009, China;,   School of Space Science and Physics, Shandong University at Weihai, Weihai 264209, China;,   Laboratory of Special Artificial Microstructure Materials and Technology, Shanghai 200092, China
Published: December 2020

In order to more comprehensively know and understand the physical properties of the metal Ag, its magneto-optical characteristics are investigated. By using light tunneling mechanism, we study the transmission and magneto-optical Faraday rotation effect of a thick metal Ag sandwiched between two dielectric photonic crystals. The results show that the transmission and magneto-optical Faraday rotation effect of a thick metal Ag can be enhanced, owing to the localized electromagnetic field at the interface between the metal Ag and photonic crystal.
Emissivity study of the array shaped blackbody in the microwave band
Authors: Jin Ming  , Bai Ming  , Miao Jun-Gang  ,   School of Electronic Information Engineering, Beihang University, Beijing 100191, China;,   Science and Technology on Space Microwave Laboratory, Xi'an Institute of Space Radio Technology, Xi'an 710100, China
Published: December 2020

Different from that in the optical band, the blackbody in the microwave band is constructed in a coated cone array structure. The blackbody of this type can be used in calibrating microwave radiometers with standard brightness radiations, and needs to have a uniform surface thermal distribution and high emissivity. The emissivity study of such a blackbody can be performed based on the Kirchhoff's law of thermal equilibrium, in a reflection determination routine. The emissivity characteristics varying with frequency have been intensively studied, but their variations with direction and polarization have not received much attentions. Starting from the Floquet mode analysis, a reflection evaluation scheme for the blackbody is presented, which is more robust than that based on the back-ward RCS determination. Based on the presented scheme, the trends of emissivity varying with frequency, direction, polarization are studied, for a microwave blackbody design. Results show that the emissivity rises as the frequency rises in a range from X band to K band; and in the low frequency band, the trend of the vertical polarization emissivity varying with elevation angle is different from that of the horizontal polarization emissivity, and there exists an obvious phenomenon that the vertical polarization emissivity declines with the increase of elevation angle. These phenomena are related to the electromagnetic absorption characteristics of the coating layer.
Melting behavior of Au-Pd eutectic nanoparticle: A molecular dynamics study
Authors: Wang Zhi-Gang  , Huang Rao  , Wen Yu-Hua  ,   College of Physics and Electronic Engineering Leshan Teachers' College, Leshan 614004, China;,   School of Physics and Mechanical and Electrical Engineering Xiamen University, Xiamen 361005, China
Published: December 2020

In this paper, we present an investigation on thermal stability of Au-Pd eutectic nanoparticle by using molecular dynamics simulation with embedded-atom potential. The results show that the melting point of Au-Pd eutectic nanoparticle is remarkably higher than that of pure Au one but lower than that of Pd one. By the analyses of Lindemann index, it is found that Au atoms first melt, then induce the melting of Pd atoms. The temperature range of melting is broader for Au-Pd eutectic nanoparticle than that for Au and Pd nanoparticles.
Solidification behaviors of undercooled Ni-P alloys
Authors: Huang Qi-Sen  , Liu Li  , Wei Xiu-Xun  , Li Jin-Fu  ,   State Key Laboratory of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
Published: December 2020

In order to gain an insight into the primary phase selection and solidification structure formation while undercooled eutectic alloys solidify, Ni100-xPx (x=18, 19, 19.6, 20, 21, atomic percent) alloy melts are undercooled to different temperatures below the equilibrium liquidus. The recalescence behavior associated with rapid solidification is monitored by a high-speed infrared pyrometer, and the solidification structure is analyzed systematically. When α-Ni/Ni3P regular eutectic forms as the primary phase during rapid solidification, single recalescence event takes place. In the resulting anomalous eutectic, fine granular grains of α-Ni are distributed uniformly in the Ni3P matrix. When the primary phase is one of the eutectic phases, however, there is a second recalescence event following the first one, resulting from nucleation of the other phase in the remaining liquid and the subsequent rapid eutectic growth. In this case, there are two types of granular grains whose sizes are significantly different from those in the anomalous eutectics. Finally, a coupled growth zone of eutectics is determined. At large undercoolings, α-Ni rather than Ni3P solidifies as the primary phase even in the Ni-P hyper-eutectic alloys due to its rapider growth kinetics.
First-principles study on the electronic structures and absorption spectra of Sm-N codoped anatase TiO2
Authors: Li Cong  , Hou Qing-Yu  , Zhang Zhen-Duo  , Zhao Chun-Wang  , Zhang Bing  ,   College of Sciences, Inner Mongolia University of Technology, Hohhot 010051, China;,   Department of Physics, Mudanjiang Normal University, Mudanjiang 157012, China
Published: December 2020

Based on first principles within density-functional theory, we establish three models of N doped anatase TiO2, Sm doped anatase TiO2 and Sm-N codoped anatase TiO2 by using the plane-wave ultrasoft pseudopotential method. We calculate their densities of states, band structures and absorption spectra. Their results show that although the N doped anatase TiO2 takes the best redshift, the Sm-N codoped anatase TiO2 makes better lifespan of electron and the Sm-N codoped anatase TiO2 is more stable.
Research on the shape memory effect and thermalelasticity of a novel intellectual damping material
Authors: Hong Jie  , Liu Bao-Long  , Zhang Da-Yi  , Ma Yan-Hong  ,   School of Jet Propulsion, Beihang University, Beijing 100191, China
Published: December 2020

In this paper, we introduce a novel intellectual damping materialshape memory alloy metal rubber (SMAMR), which is made from the shape memory alloy through the process similar to that for metal rubber. The shape craft, shape memory effect and mechanical properties are tested and discussed. The results show that the SMAMR has the combination properties of both shape memory alloy and metal rubber, such as high elasticity and damping capacity, low density, designable porosity, shape memory effect, and temperature dependent mechanical properties. The SMAMR not only has modulus and loss factor varying linearly with temperature during the phase transformation between Martensite and Austenite, which is quite available in the active control of vibration; but also has the modulus and loss factor large enough to be used as bearing structure. So the SMAMR is a significant integration of both functional material and structural material, and is quite attractive in active vibration control.
Preliminary analyses on characteristics of sea surface temperatures in Kuroshio and its extension and relations to atmospheric circulations
Authors: Wang Shan-Shan  , Guan Yu-Ping  , Li Zhi-Jin  , Chao Yi  , Huang Jian-Ping  ,   College of Atmospheric Science, Lanzhou University, Lanzhou 730000, China;,   State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China;,   Jet Propulsion Laboratory, California Institute of Technology, Pasadena CA91109, USA
Published: December 2020

A sea surface temperature (SST) based index, denoted as KI, is designed to characterize the holistic feature of Kuroshio east of the Tokara-kaikyo and its extension on the purpose of predict its SST trend. The KI is calculated on the base of the Hadley Center's monthly SSTs during the period 1941-2009. The wavelet analysis showed that the KI displays inter-annual and inter-decadal oscillations, dominated by quasi-triennial, quasi 7-yr and 20-yr time scales. In addition, the KI is shown to be phase-locking to seasonal cycles. It is found that there are significant temporally-lag correlations between the KI and the Pacific decadal oscillation (PDO) index as well as between the KI and the ENSO index. A set of composition analyses using the NCEP/NCAR reanalyses indicate that when the KI shows a positive anomaly, the SST becomes abnormally warm in the equatorial eastern. Pacific, the Hadley circulation is intensified, and consequently the transportation of the westerly momentum is enhanced. The enhanced Hadley circulation and transportation of the westerly momentum give rise to the deepened Aleutian low pressure, then cool the Kuroshio extension and the north Pacific basin and cause the KE extend east. The above " ENSO-PDO-Kuroshio" process need some response time, that is to say, we can forecast the SST variation on the Kuroshio on the basis of the ENSO and PDO, which is very significant to predict the climate in China.
Prediction of smoothed monthly mean sunspot number based on chaos theory
Authors: Tang Jie  , Zhang Xiong  ,   School of Physics and Telecommunication Engineering, Shaanxi University of Technology, Hanzhong 723001, China;,   College of Physics and Electronics, Yunnan Normal University, Kunming 650092, China
Published: December 2020

Long-term prediction of sunspot activity is of great importance for the space activity, communication, disaster prevention and so on. Cumulative error is main shortcoming of weighted one-rank local-region forecasting model for multi-steps prediction of chaotic time series. The radial basis function neural network forecasting model based on phase reconstruction is presented for chaotic time series prediction. The model is applied to the prediction of smoothed monthly mean sunspot numbers for the 22nd and 23rd sun cycles, and compared them with the observations. The results indicate that the mean absolute errors are 5.47 and 2.82, 15 to the maximum in absolute errors, and the mean relative errors are 5.45% and 4.60%, 15.00% to the maximum in relative errors. These results show that this prediction method can be successfully used to predict the smoothed monthly mean sunspot numbers. The predicted maximal smoothed monthly mean sunspot number is 104.77 that will appear in January 2013 for 132 months of cycle 24 from January 2009 to December 2019.
Broadcast and multicast in quantum teleportation internet
Authors: Zhou Xiao-Qing  , Wu Yun-Wen  ,   Department of Physics, Jishou University, Jishou 416000, China
Published: December 2020

The physical principle of broadcast and multicast is given. When Alice needs to send out an information, she sends out a conjunction claim signal to the switch that connects with hers. After receiving the conjunction claim the signal, the switch pass to examines the purpose address to judge whether it is a point-to-point communication or broadcast and multicast. If the purpose address is A or B or C address, then the switch carries on the correspondence operation of point-to-point; if the purpose address is a D address or an address (local or appointed network webcasting) with special meaning, then the switch carries on the correspondence operation of broadcast and multicast. With broadcast and multicast, the fidelity decreases with the increase of receiving terminal number, and its limit is 2/3.