bluuebunny/crossref_metadata_2025 huggingface dataset:
Radiation spectrum of Kerr-Newman-de Sitter black hole and correction to its entropy
Authors: Zhang Li-Chun  , Zhao Ren  ,   山西大同大学物理系，理论物理研究所,大同 037009
Published: December 2020

We extend the Damour-Ruffini method and discuss Hawking radiation of Kerr-Newman-de Sitter black hole. Under the condition that the total energy and angular momentum of spacetime are conserved, taking the reaction of the radiation of particles to the spacetime into consideration and considering the interrelation between the black hole event horizon and the cosmological horizon, we obtain the black hole radiation spectrum. This radiation is no longer a strictly pure thermal spectrum. It is related to the change in Bekenstein-Hawking(B-H) entropy corresponding to black hole event horizon and the cosmological horizon. It is shown that the result satisfies the unitary principle. We also derive the correction term of B-H entropy. It leads to a new understanding of thermal radiation of the black hole.
Erosion phase transition of Fe2Al5 coating in molten zinc
Authors: Sun Wen-Xiu  , Yan Dian-Ran  , Chen Xue-Guang  , Dong Yan-Chun  , Li Xiang-Zhi  ,   河北工业大学材料科学与工程学院，天津 300132
Published: December 2020

The mechanism of erosion phase transition of Fe2Al5 coating in molten zinc was investigated. Experimental results indicated that etched grooves caused by interfacial tension equilibrium driving formed on sample surface. The Fe2Al5 phase, on where zinc did not adhere at the early stage of erosion, was infiltrated by zinc and solid solution Fe2Al5-Znx (η phase) was formed due to zinc atoms diffusing into Fe2Al5 phase. The erosion process of Fe2Al5 in molten zinc is directed melt at the interface caused by phase transition to drive. There were three types of phase interface，η/L,η/(η+δ)/L and η /(η+δ)/δ+L，formed in corroded area .The solid (S) / liquid (L) interface was phase-equilibrium interface and the S/S interface like η/(η+δ) and (η+δ)/δ were non phase-equilibrium interfaces at erosion temperature. The demand of phase-equilibrium interfaces and phase transitions of non-equilibrium interfaces, η→(η+δ) and (η+δ) →δ, made the S/L interface move towards to solid phase and Fe2Al5 phase was corroded by molten zinc.
Time delay to enhance the giant suppression in a bistable system
Authors: Lin Ling  , Yan Yong  , Mei Dong-Cheng  ,   (1)思茅师范高等专科学校计算机科学系，普洱  665000; (2)云南大学物理系，昆明  650091; (3)云南大学物理系，昆明  650091；思茅师范高等专科学校计算机科学系，普洱  665000
Published: December 2020

Effects of time delay on the active rate of a bistable system was investigated. Using the steepest-descent approximation method, the analytical expression of the mean first passage time and the active rate of the bistable system with time delay was derived under the condition of small delay time. The numerical computations show that the time delay enhances the resonance suppression in the system.
Establishment and structure properties of the scale-free Koch network
Authors: Liu Jia-Xue  , Kong Xiang-Mu  ,   曲阜师范大学物理工程学院，曲阜  273165
Published: December 2020

According the iterative algorithm of Koch curve, we generate a Koch network by considering tetrahedron as the basic unit of the iteration and investigate its structure properties, such as degree distribution, clustering coefficient, and average path length, degree correlation, analytically. The results show that the network is scale-free and the exponent of the degree distribution is γ≈332. The clustering coefficient tends to be 0870435 in the limit of large iteration and the study of the average path length proves that the network exhibits small world effect. We also find that the generated network is not degree uncorrelated because the function knn(k) is dependent on the degree of site.
Optimal control for uncertainty dynamic chaotic systems
Authors: Zhu Shao-Ping  , Qian Fu-Cai  , Liu Ding  ,   (1)西安理工大学自动化与信息工程学院，西安  710048; (2)西安理工大学自动化与信息工程学院，西安  710048；西安财经学院统计学院，西安  710061
Published: December 2020

For chaos control problem, in accordance with the constraints of control system energy, a quadratic objective function is first determined, and then a simple method for obtaining the optimal control law is proposed. This method gives the optimal control law by solving linear quadratic optimal control problem and avoids the difficulty of solving Hamilton-Jacobi-Bellman equation. Using Lyapnuov method, we prove the stability of the closed-loop system. For the unified chaotic system and Liu chaotic system the simulation results show the effectiveness of the control method.
Control of chaos in double-loop current-mode DC/DC based on adaptive slope compensation
Authors: Lai Xin-Quan  , Li Zu-He  , Yuan Bing  , Wang Hui  , Ye Qiang  , Zhao Yong-Rui  ,   西安电子科技大学电路CAD研究所，西安 710071
Published: December 2020

The method of adaptive slope compensation and its circuit structure are proposed in this paper. With this method, bifurcation and chaos in double-loop current-mode buck DC/DC are controlled with good performance. The discrete model of double-loop current-mode buck DC/DC used in stability analysis is build and the condition for the system operating stably under double-loop control is derived theoretically. Further more, the relationship between the adaptive coefficient k and the maximum duty ratio on which the system will operate stably is derived. The agreement of simulation results with the theoretical analysis shows that adaptive slope compensation can control bifurcation and chaos effectively, and it extends the system working range and improves the dynamic response characteristics.
Adaptive modified function projective synchronization of different hyperchaotic systems
Authors: Wang Jian-An  , Liu He-Ping  ,   北京科技大学信息工程学院,北京 100083
Published: December 2020

This article treats the modified function projective synchronization between the hyperchaotic Lorenz-Stenflo(LS) system and a novel hyperchaotic CYQY system, and also that between the LS system and hyperchaotic Chen system, which have completely unknown parameters. By utilizing Lyapunov stability theory and active control method, the adaptive controllers and parameter update laws are derived to make the states of different hyperchaotic systems to attain adaptive modified function projective synchronization. The systems unknown parameters can be identified simultaneously. Numerical simulations are presented to demonstrate the effectiveness of the proposed methods.
A new piecewise nonlinear chaotic map and its performance
Authors: Zhang Xue-Feng  , Fan Jiu-Lun  ,   西安邮电学院信息与控制系,西安 710061
Published: December 2020

Properties of logistic chaotic map is studied, and it is pointed out that phase space is not ergodic when parameters of the chaotic system change. Based on these analysis, a piecewise logistic chaotic map is constructed. The bifurcation diagram and Lyapunov exponent of logistic and piecewise logistic map are studied, and the properties of randomicity, correlation coefficient and power spectrum etc. of the sequences generated by these two maps are analyzed experimentally. A new performance evaluation index for chaotic system, the bifurcation iteration time, is defined. Simulation results show that the defined piecewise logistic map is not only ergodic in phase space, and its corresponding chaotic performance evaluation indices are also better.
Adaptive tracking control and synchronization of fractional hyper-chaotic Lorenz system with unknown parameters
Authors: Zhao Ling-Dong  , Hu Jian-Bing  , Liu Xu-Hui  ,   中北大学电子测试技术国家重点实验室,仪器科学与动态测试教育部重点实验室,太原  030051
Published: December 2020

Based on the fractional stability theory, the controller and recognizing rules of the uncertain parameters are designed. Tracking control and synchronization of fractional hyper chaotic Lorenz system is realized. Numerical simulation verifies the effectiveness of the approach of this paper.
Dynamical behaviour of FitzHugh-Nagumo neuron model driven by harmonic noise
Authors: Song Yan-Li  ,   天津大学物理系,天津 300072
Published: December 2020

The FitzHugh-Nagumo neuron model driven by a harmonic noise is investigated, whose dynamic behaviours are influenced by the frequency and the damping parameters of noise. The spikes train varies with these two parameters changing. The FitzHugh-Nagumo neuron has resonance characteristic and exhibits stronger response to noise with a given frequency. Undernoise with this frequency parameter, the spikes train is more regular and the coefficient of coherent resonance reaches the minimum. The larger the damping parameter of the noise is, the more the different ingredients are, thus the synchronization between neuron and noise becomes more imperfect and the coefficient of coherent resonance is larger.
Error correction of theory model of process stress accelerated test
Authors: Guo Chun-Sheng  , Shan Ni-Na  , Feng Shi-Wei  , Ma Wei-Dong  ,   北京工业大学电子信息与控制工程学院,北京 100124
Published: December 2020

To correct the error in theoretical model of process stress accelerated test, a new calculation method is proposed. The new method, based on computer-aided calculation, can significantly reduce the error of the model. Theoretical data is calculated using both the novel model algorithm, which is the root test method, and the old model algorithm. The results shows that the old model algorithm can generate errors of more than 13% in the activation energy, and of errors more than 150% in the extrapolated lifetime（Q≤10 eV）,while the novel model algorithm generates errors in less than 1% in activation energy, and errors less than -41% in the extrapolated lifetime.
Accurate determination of optical constants and thickness of absorbing thin films by a combined ellipsometry and spectrophotometry approach
Authors: Zhou Yi  , Wu Guo-Song  , Dai Wei  , Li Hong-Bo  , Wang Ai-Ying  ,   中国科学院宁波材料技术与工程研究所,宁波 315201
Published: December 2020

A new approach for accurate measurement of the absorbing film thickness and optical constants by combined ellipsometry and spectrophotometry is introduced. The details are studied in terms of the mathematical models and formulats in comparison with the commonly used method which is only dependent on the ellipsometry data specifically. Using variable angle spectroscopic ellipsometry (VASE), the diamond-like carbon film deposited by a glow discharge technique was characterized at the wavelength range of 250—1700 nm. The results indicate that, generally, it is rather difficult to determine the thickness and optical constants of absorbing film accurately and rapidly due to the strong correlation between thickness and n, k. By simultaneously fitting ellipsometry parameters and film transmittance, however, the optical constants could be obtained easily and accurately from a unique solution without any predetermined dispersion model. The fitting results of DLC show that this approach is a promising method to determine the thicknesses and optical constants of films, especially of the thin absorbing films.
Analytic solutions of point-reactor neutron kinetics equations with temperature feedback under the condition of negative inserted step reactivity
Authors: Li Hao-Feng  , Chen Wen-Zhen  , Zhang Fan  , Shang Xue-Li  ,   海军工程大学核能科学与工程系,武汉  430033
Published: December 2020

The prompt and delayed supercritical process of a nuclear reactor with temperature feedback is taken into consideration. The solutions of the point-reactor neutron kinetics equations under the condition of temperature feedback and negative inserted step reactivity are investigated. Different analytic models are given. The new solution is also proposed and compared with those published in literature. It is found that (1) the model and related solution for prompt supercritical can not be applied for the process of large negative inserted step reactivity; (2) under the condition of the same initial power the precursor prompt jump approximation model is better than the neutron prompt jump approximation model; and (3) the temperature prompt jump approximation model is always better than the precursor and neutron prompt jump approximation models for any initial power and negative inserted step reactivity, which is so far the most accurate analytical model.
Thermonuclear burn characteristics of compressed deuterium-tritium microspheres
Authors: Wu Jun-Feng  , Ye Wen-Hua  , Zhang Wei-Yan  ,   北京应用物理与计算数学研究所,北京  100094
Published: December 2020

The thermonuclear burn characteristics of compressed deuterium-tritium microspheres are simulated with LARED-S code based on the isochoric and isobaric models. Two examples of the isochoric model are simulated and compared with the other present data for validating the LARED-S code. For the isobaric model, numerical results characterizing the thermonuclear burn for a broad range of initial conditions are presenteal. It is shown that the yield and burn-up fraction increase with the total fuel mass, pressure and main-fuel density. It is necessary for the hot-spot to reach temperatures up to 70 to 80 MK and areal density 3 to 4 kg· m-2 to obtain considerable fusion energy. If the main-fuel density is increased high enough, the hot-spot condition for ignition could be broadened to a lower limit. Finally, the results of the isobaric model are compared with those of the actual ignition targets simulated with the LARED-S code.
Experimental investigation of Stark effect of ultra-cold 39D cesium Rydberg atoms
Authors: Zhu Xing-Bo  , Zhang Hao  , Feng Zhi-Gang  , Zhang Lin-Jie  , Li Chang-Yong  , Zhao Jian-Ming  , Jia Suo-Tang  ,   山西大学物理电子工程学院,量子光学与光量子器件国家重点实验室,太原 030006
Published: December 2020

In this paper, we investigate the Stark effect of ultra-cold 39D cesium Rydberg atoms in low-field. The Stark structure of 39D Rydberg states is calculated numerically. The cold cesium atoms are excited to Rydberg states via two-step process and the Stark spectra are obtained by field-ionization method. The scalar and tenson polarizabilities of 39D cesium Rydberg atoms are measured to be α5/22=62(7) MHz·V-2cm2，α5/20=－146(13) MHz·V-2cm2, α3/22=73(6) MHz·V-2cm2，α3/20=－106(20) MHz·V-2cm2 respectively. The experimental values are in agreement with the theoretical results.
Exact quantum motion of a single trapped ion interacting with standing laser pulses in Lamb-Dicke regime
Authors: Yang Mei-Rong  , Hai Wen-Hua  , Lu Geng-Biao  , Zhong Hong-Hua  ,   湖南师范大学物理系，长沙 410081
Published: December 2020

We investigate the secular motion of a single Paul-trapped ion in the Lamb-Dicke regime, which interacts with a sequence of standing laser pulses. By using the ansatz method, we get an exact quantum solution of the system. Based on the wave-packet trains described by the exact solution, we find that: i) The center, height and width of the wave-packet trains depend on the strength of laser pulses, the deformation and spread of the wave-packet trains can be controlled by adjusting the strength of laser. ii) Energy expectation values of the ion show jumps at the instantaneous switching on of the laser pulses. In the time intervals when the laser pulses are switched off some narrow energy bands are generated. iii) When the strength of laser pulses reaches a critical value, the system changes its stability.
The effect of symmetrical isotopic substitution in Ne-H2 collision
Authors: Linghu Rong-Feng  , Xu Mei  , Wang Xiao-Lu  , Lü Bing  , Yang Xiang-Dong  ,   (1)四川大学原子与分子物理研究所,成都 610065; (2)四川大学原子与分子物理研究所,成都 610065；贵州师范大学物理与电子科学学院,贵阳 550001
Published: December 2020

The differential and partial wave scattering cross sections of Ne-H2(D2,T2) collisions have been calculated by close-coupling approximation method using Tang-Toennies potential model at the incident energy of 83.8 meV. The calculated differential cross sections are in good agreement with the experimental data and the partial wave cross sections match well with the published data. With the same method and potential model, the differential cross sections and the partial wave cross sections of Ne-H2(D2,T2) collisions have been derived and analyzed. The rules of the effect of symmetrical isotopic substitution are obtained.
Molecular dynamics study of relaxation and local structure changes in a rapidly quenched molten Cu57 cluster
Authors: Fan Qin-Na  , Li Wei  , Zhang Lin  ,   东北大学理学院，沈阳 110004
Published: December 2020

Relaxation and local structure changes of a molten Cu57 cluster during rapidly quenching have been studied by molecular dynamics simulation using embedded atom method. With decreasing quenching temperature, atom motion details are analyzed using three factors, including the mean square displacement, incoherent intermediate scattering function, and non-Gaussian parameter, while the local structure changes are identified by pair analysis. Simulation results reveal that after a drastic collective motion of atoms, the temperature greatly affects the relaxation processes of the cooled cluster. At a high quenching temperature, after atoms dramatically move in a β relaxation region, diffusion motion of the atoms plays a dominant roles followed by non-diffusion rearrangements of local atomic structures, and no nucleation occurs. When the temperature decreases, local structure changes of atoms occur as the initial dramatic motion, then through the diffusion of atoms in the α relaxation region, and some unstable icosahedral structures are observed. At a low quenching temperature, the structure changes in the α relaxation region result mainly from non-diffusion rearrangement of the atom positions, and a notable amount of icosahedral structures are formed.
Analysis of modes in 　pairing of single-negative material
Authors: Zhang Rui  , Yang Ya-Ping  ,   同济大学物理系，上海  200092；上海市特殊人工微结构材料与技术重点实验室,上海 200092
Published: December 2020

The modes in a double-layer of single-negative material have been investigated. The conditions for the existence of different modes have been analyzed. The relations between different modes and material parameters are considered. Tunneling mode appears when the general zero average permittivity and permeability conditions are satisfied. When the wave guide condition is satisfied, electromagnetic wave is evanescent outside the material, and the field is mainly localized at the interface of the two single-negative layers.
Coherence vortex properties of partially coherent vortex beams
Authors: Cheng Ke  , Zhang Hong-Run  , Lü Bai-Da  ,   (1)四川大学激光物理与化学研究所，成都  610064; (2)四川大学激光物理与化学研究所，成都  610064；成都信息工程学院光电技术学院，成都  610225; (3)四川大学应用物理系，成都  610065
Published: December 2020

The analytical expression for the propagation of partially coherent flat-topped vortex beams through a paraxial optical ABCD system is derived and used to study the coherence vortex properties of partially coherent vortex beams in the focal region and free space. It is shown that the coherence vortex depends on the beam order N，spatial coherence parameter α and position (x1，y1) of the reference point. Depending on the choice of the reference point，the zero point of the spectral degree of coherence may be present or absent. In particular，if x1=y1=0 is chosen，the phase at the zero point of the spectral degree of coherence may be determinate，thus the coherence vortex does not exist.
Theoretical and experimental study of multi-element coherent fiber array
Authors: Fan Xin-Yan  , Liu Jing-Jiao  , Liu Jin-Sheng  , Wu Jing-Li  ,   (1)哈尔滨工业大学可调谐激光国家重点实验室，哈尔滨 150001; (2)中国科学院长春光学精密机械与物理研究所，长春 130033
Published: December 2020

The theoretical model of the hexagonal fiber array is established based on Fraunhofer diffraction theory. The far field distribution of the hexagonal fiber array is presented. Energy contained in the central lobe and Strehl ratio are taken as the two evaluation parameters of coherent combined system. The effects of arrangement, amplitude，filling factor and phase errors on far field distribution are analyzed and simulated. A seven-element hexagonal fiber array with a hexagonal prism is experimentally constructed. The hill climbing method is employed to detect and lock the element phase. The filling factor of the coherent array achieves 066. The combined beam of Strehl ratio of 070 and energy contained in the central lobe of 040 is experimentally obtained. And the energy contained in the central lobe of two-element linear array and four-element square array are 045 and 018, respectively.
Nonclassical properties of a two-mode SU(2) coherent field resonantly interacting with a three-level Λ-type atom
Authors: Zheng Nai-Qing  ,   宁德师范高等专科学校物理与电气工程系,宁德 352100
Published: December 2020

Nonclassical properties of a two-mode field initially in an SU(2) coherent state resonantly interacting with a three-level Λ-type atom are investigated by means of the quantum theory and numerical calculations. The dependence of the nonclassical properties on the total photon number of the two-mode, the partition parameter and the coupling constant is discussed for three cases: (1) no state-selective atomic measurement; (2) direct state-selective atomic measurement; and (3) state-selective atomic measurement after the application of a classical field. The results indicate that when the total photon number of the two-mode is increased or the state-selective measurement is performed on the atom, the difference squeezing of two-mode is distinctly enhanced; and when the partition parameter is decreased or the state-selective measurement is performed on the atom after the application of a classical field, the average intensity of the sub-Poisson statistic distribution of mode a is reduced and that of mode b is enhanced; when the total photon number of the two modes is increased or the direct state-selective measurement is performed on the atom, the anti-correlation character between the two modes is preserved, but the average intensity of the anti-correlation is reduced; and when the direct state-selective measurement is performed on the atom, the Cauchy-Schwartz inequality is violated.
Optical limiting of a methyl-red dye doped suspended carbon nanotube mixture
Authors: Shen Xue-Ju  , Wang Long  , Han Yu-Dong  , Li Zheng  ,   解放军军械工程学院光学与电子工程系,石家庄  050003
Published: December 2020

The optical limiting effect of Methyl-red dye doped suspended carbon nanotube mixture on 532 nm lascr lighter is studied in experiment. The experiments were carried out with samples of different thickness radiated by laser with different repetition frequency, and the results are compared with the results got from pure suspended carbon nanotubes. The results showed that, if the suspended carbon nanotubes with 60% transmission is doped with some Methyl-red dye, its solubility can be improved and the input limiting threshold decreases from 250 μJ to 200 μJ. The clamped output energies for samples with 2 mm and 5 mm thickness decrease from 45 and 20μJ to 35 and 9 μJ, respectively.
Propagation of complex argument Laguerre-Gaussian beams in strongly nonlocal nonlinear media
Authors: Chen Li-Xia  , Lu Da-Quan  , Hu Wei  , Yang Zhen-Jun  , Cao Wei-Wen  , Zheng Rui  , Guo Qi  ,   华南师范大学光子信息技术广东省高校重点实验室,广州  510006
Published: December 2020

In this paper, we obtain the analytical solution of the off-waist inputted complex argument Laguerre-Gaussian beams and their mean squared beam width in nonlocal nonlinear media. The propagation of the complex argument Laguerre-Gaussian beams in the nonlocal nonlinear media is investigated in detail. The examples show that the pattern shape of a (n,m) mode complex argument Laguerre-Gaussian beam varies periodically with the period Δz=πzc in strongly nonlocal nonlinear media if n≠0.But if n=0, its pattern shape remains unvaried and the beam width varies periodically during propagation. Under the off-waist incident condition, the propagation of the (0,m)mode complex argument Laguerre-Gaussian beam behaves as a breather during propagation, no matter what the power of the incident beam is. Only when the beam is input at the waist and the input power equals the critical power would the breather be reduced to a soliton.
Physical and infrared optical properties of mixed SrF2-CaF2 thin films
Authors: Yu Tian-Yan  , Qin Yang  , Liu Ding-Quan  , Zhang Feng-Shan  ,   中国科学院上海技术物理研究所，光学薄膜与材料研究室，上海 200083
Published: December 2020

The mixed SrF2-CaF2 thin films with the same thickness were deposited by the techniques of resistant evaporation and electron beam evaporation respectively. The physical and infrared optical properties of the thin films were investigated. The optical constants in the infrared region were determined quantitatively which fills the gap of these data. At the same time, we provided a method to obtain gradient index films. We also used the mixed SrF2-CaF2 with a proportion of 1∶1 as the lower index material to deposit multilayer coatings. A broadband antireflection coatings with high optical performance was developed.
Phase-shifted compensation of channel-space on fiber grating comb filter
Authors: Hou Fen-Fei  , Yang Hong  ,   南京师范大学物理科学与技术学院，南京  210096
Published: December 2020

As the channel-space of the comb filter based on chirped sampled fiber Bragg grating and phase shift is not accurate and the multi-channel is unable to channel the standard frequency, we discussed and calculated the error between theory and practice, which has been verified by simulation. Then a compensation method by introducing phase shift between the samples was proposed, and a 100 channel comb filter with accurate 40 GHz channel-spacing was simulated, which lays a good foundation for fabricating comb filters with accurate transmission peak in the future.
Effect of the substrate potential on the static friction force in the Frenkel-Kontorova model
Authors: Li Xiao-Li  , Liu Feng  , Lin Mai-Mai  , Chen Jian-Min  , Duan Wen-Shan  ,   (1)固体润滑国家重点实验室，中国科学院兰州化学物理研究所，兰州  720000; (2)西北师范大学物理与电子工程学院，兰州  730070
Published: December 2020

By using the one-dimensional Frenkel-Kontorova (FK) model, we study the maximum static friction force between the two surface layers which are in contact. The relation between the substrate potential and the static friction force is studied in this paper. The effect of parameters of the upper layer such as the elastic coefficient K on the static friction force are also investigated.Results are obtained for three cases for which the ratio of the atomic distance to the period of potential field is commensurate, or equal to the golden mean, or the spiral mean respectively. The results show that both the form of the substrate potential and the commensurability have sigificant effect on the static friction force.
Lattice Boltzmann simulation of droplet motion driven by gradient of wettability
Authors: Shi Zi-Yuan  , Hu Guo-Hui  , Zhou Zhe-Wei  ,   上海大学上海市应用数学和力学研究所，上海 200072
Published: December 2020

The lattice Boltzmann method is used to simulate numerically the droplet motion driven by Marangoni effect, which is induced by surface tension gradient on the solid-liquid interface, with the consideration of interaction between solid and liquid molecules. The computation results are well compared with the theoretical prediction available for smaller surface tension gradient, whereas the translation velocity of droplet is smaller than the theoretical value for larger gradient, because some assumptions, such as the quasi-equilibrium and non-deformable droplet, are not satisfied in the theoretical analysis anymore. Vortical structure with a solid-like core is found in the droplet when it moves to the hydrophilic end. The variations of velocity and contact angle of droplet are found to be oscillating with time for larger gradient of wettability.
Evolution of H2/O2 mixture plasma under different initial temperatures
Authors: Lan Yu-Dan  , He Li-Ming  , Ding Wei  , Wang Feng  ,   空军工程大学工程学院，西安  710038
Published: December 2020

This paper presents a numerical simulation of the evolution of the main particles in H2/O2 mixture plasma under different initial temperature, and gives the time-variation laws of the density of the main charged and neutral particles in plasma after discharge begins. The results show that the density of main active particles in H2/O2 mixture plasma is reduced with time, and the required time for the equilibrium of chemical reactions reduces with increasing initial temperature.
Diagnostics of the atmospheric pressure plasma jets for plasma enhanced chemical vapor deposition of polycrystalline silicon thin film
Authors: Liu Li-Ying  , Zhang Jia-Liang  , Guo Qing-Chao  , Wang De-Zhen  ,   大连理工大学物理与光电工程学院，大连 116023
Published: December 2020

The characteristics of the radio frequency plasma jets at atmospheric pressure in Ar/SiCl4/H2 gas mixture were studied in this paper by using optical emission spectroscopy. Firstly, the electron excitation temperature of plasmas was calculated from the Si atom spectral emission using Boltzmann plots, and then, based on the temperature, the number density of the Si atoms in the plasmas and the dissociation ratio of the SiCl4 were estimated. Finally, the dependence of the excitation temperature, the number density of the Si atoms and the dissociation ratio of the SiCl4 on the discharge power and the gas flow rate were presented.
CHF3 dual-frequency capacitively coupled plasma
Authors: Hu Jia  , Xu Yi-Jun  , Ye Chao  ,   苏州大学物理科学与技术学院，江苏省薄膜材料重点实验室，苏州 215006
Published: December 2020

This paper investigates the intermediate gas phase in the CHF3 dual-frequency capacitively couple plasma (DF-CCP) driven by the high-frequency (HF) of 1356 MHz，2712 MHz or 60 MHz and the low-frequency (LF) of 2 MHz power sources，which was used to etch the SiCOH low dielectric constant (low-k) films. The increasing of 2 MHz LF power led to the increase of F radical concentration，and the increasing of HF frequency from 1356 MHz and 2712 MHz to 60 MHz led to the increase of CF2 concentration and a poor spatial uniformity of F radical between the electrodes. According to the electron temperature distribution at different LF power and HF frequency，and the dependence of ion energy on the high frequency，the CF2radicals were found to come from the CHF3 dissociation by the electron-neutrals collisions，and the F radical from the CHF3 dissociation induced by the ions-neutrals thermal collisions.
Molecular dynamics simulation of the evaporation of the surface wall of multi-wall carbon nanotubes at high temperature
Authors: Wang Wei  , Zhang Kai-Wang  , Meng Li-Jun  , Li Zhong-Qiu  , Zuo Xue-Yun  , Zhong Jian-Xin  ,   湘潭大学材料与光电物理学院，量子工程与微纳能源技术研究所，湘潭 411105
Published: December 2020

We have used molecular dynamics (MD) simulation to investigate the evaporation of the surface wall of multi-wall carbon nanotubes (MWCNTs) at high temperature，using the environment dependent interatomic potential (EDIP) to describe the C—C interaction in carbon nanotube. The simulation results show that the Stone-Wales defect in the surface wall of a multi-wall carbon nanotube vibrates violently，which causes C—C bond breaking and evaporation of atoms along the circumferential directions of the nanotube. The formation of Stone-Wales defect is attributed to the atomic thermal motion or tensile strain. Using the Lindemann index as a criterion，we found that the surface wall of MWCNT evaporates around 2290 K. Our simulation results agree very well with the observation of the surface wall evaporation of the MWCNT at 2000 ℃.
First-principles study of the thermal transport property of Y3Al5O12
Authors: Liu Cheng-Cheng  , Cao Quan-Xi  ,   西安电子科技大学技术物理学院，西安  710071
Published: December 2020

Based on density functional perturbation theory (DFPT) combined with the norm-conserving pseudopotential method，the lattice dynamic simulation is presented. The total phonon density of states，partial phonon density of states and phonon dispersion spectrum of YAG are obtained. By using the special point sampling method within the first Brillouin zone，the special heat capacity and the population averaged group speed of phonon of YAG are calculated. The anharmonic phonon mean free path is calculated theoretically within anharmonic interaction and by using the Fermis golden rule scheme combined with the special point sampling method within the first Brillouin zone. We comprehensively considered two types of the phonon scattering mechanisms，the thermal conductivity of YAG ceramic is obtained. The result indicates that the grain boundary scattering plays a major role in the thermal resistance at low temperature in YAG ceramic，while the three-phonon interaction contribution to the thermal resistance will prevail above a certain temperature. Meanwhile，the viewpoint held by Y. Sato et al. that the difference of the thermal conductivity of between YAG ceramic and single crystal can be ignored above room temperature is theoretically proved. The temperature variations of the calculated thermal conductivity and special heat capacity agree well with the experimental results.
The effect of electric pulses on the specific heat of polycrystalline La0.7Ca0.3MnO3
Authors: Wu Zhi-Hua  , Xie Hua-Qing  ,   上海第二工业大学城市建设与环境工程学院，上海 201209
Published: December 2020

The specific heat of polycrystalline La0.7Ca0.3MnO3 at different resistance states induced by electric pulses was studied. It was found that the specific heat decreases with decreasing resistance, and the change is reversible. The reversible change of specific heat was shown to be mainly due to the ferromagnetic-spin-waves component and charge carriers component by fitting the specific heat data. These results indicate that the electric pulses modulated the magnetic configuration of LCMO at low temperature, which would result in large variation in magnetization and specific heat associated with ferromagnetic-spin-waves.
General solutions to spin transportation of electrons through equilateral polygon quantum rings with Rashba spin-orbit interaction
Authors: Fu Bang  , Deng Wen-Ji  ,   华南理工大学物理系，广州 510641
Published: December 2020

Based on the previous work (Li P, Deng W J 2009 Acta Phys. Sin. 58 02713), the quantum transportation of electron through arbitrary equilateral polygons quantum rings with Rashba spin-orbit interaction is studied. With the typical method of quantum network and the Landauer-Büttiker formalism, we analytically solve the scattering problem of electron through equilateral polygonal quantum ring, and obtain the relevant formula for spin transportation conductance. The characteristics of the conductance varying with the wave-vector of electron, the strength of spin-orbit interaction, the number of polygon edges, and the ways of leads connecting to quantum rings are discussed. In the limit of infinite number of edges of polygon, we prove that the formula is consistent with the results obtained directly from the circular model of quantum rings.
Static surface states and bulk traps in AlGaN/GaN HEMT including hot electron and quantum effects
Authors: Hao Li-Chao  , Duan Jun-Li  ,   (1)上海交通大学医学院附属新华医院，上海  200240; (2)同济大学物理学院，上海  200092
Published: December 2020

The effects of static surface states and bulk traps on output characteristics have been studied. The effects of surface charge and bulk traps on current collapse, saturation current and knee voltage are investigated, and their relationships have been determined. The results show that the increase of the surface charge can exhaust the two-dimensional electron gas, and reduce the current collapse effect and saturation current, inducing the abnormal shift of the knee voltage. At the same time, reducing the bulk traps can alleviate the current collapse effect and increase the saturation current with the slight change of the knee voltage. At low lattice temperature, the hot electron effect and quantum tunneling effect play an important role in the current collapse. By using the hydrodynamics model, possible physical mechanisms are discussed, and an approach is proposed to reduce the effects of the static surface states and bulk traps on the output characteristics.
Mechanism of magnetoresistance impacted by Co doped in La0.8Sr0.2MnO3 ferromagnetic metallic
Authors: Jiang Kuo  ,   西南科技大学国防科技学院，绵阳  621010
Published: December 2020

Through measurement of saturation magnetic moment and transport of La0.8Sr0.2Mn1-yCoyO3 (y≤02), the mechanism of magnetoresistance (MR) impacted by Co doping is investigated. The results show that Co3+ is in the low-spin state in La0.8Sr0.2 Mn1-yCoyO3(y≤02). The magnetic exchange interactions of the type Mn3+—O—Co3+—O—Mn3+ is weaker than that of the double exchange interaction between Mn3+-Mn4+, and the magnetoresistance near the Curie temperature TC decreases with the increase of Co concentration. On the contrary, low-temperature magnetoresistance increases with the increase of Co concentration owing to the antiferromagnetic exchange coupling between Co2+ and eg itinerant electron.
An effective active phase compensation method for quantum key distribution system
Authors: Wang Jin-Dong  , Qin Xiao-Juan  , Wei Zheng-Jun  , Liu Xiao-Bao  , Liao Chang-Jun  , Liu Song-Hao  ,   (1)广东广播电视大学工程技术系，广州  510091; (2)华南师范大学信息光电子科技学院光子信息技术广东省高校重点实验室，广州  510006
Published: December 2020

Quantum key distribution (QKD) system must be robust enough in practical communication. The system performance is notably affected by phase drift. For the fiber-based phase-encoded quantum key distribution system, the Faraday-Michelson QKD scheme can auto-compensate the birefringence of fiber, but phase drift caused by environment variations is still a serious problem in practical operation. In this paper, the major schemes to compensate for the phase drift are analyzed in detail and an “five-phase”effective active phase compensation method is proposed. The comparison with other two major active phase compensation schemes also given. The result shows that this method uses less time to acquire the parameter of phase drift with the same precision and it can be used in phase-encoded QKD systems without introducing additional devices.
Fist-principle calculation for electronic structure of M’-GdTaO4
Authors: Gu Mu  , Lin Ling  , Liu Bo  , Liu Xiao-Lin  , Huang Shi-Ming  , Ni Chen  ,   同济大学物理系,上海市特殊人工微结构材料与技术重点实验室，上海 200092
Published: December 2020

The electronic structure of M’ type GdTaO4 is studied by first-principle pseudopotential calculation within the frame of density-functional theory. The calculated band structure of M’-GdTaO4 revealed that the top of the valence band is dominated by O-2p and the bottom of the conduction band is dominated by e orbits of Ta-5d. The spin-up and spin-down electrons of Gd-4f are located at 627 eV below the top of the valence band and at 301 eV above the bottom of the conduction band when on-site Coulomb interaction Ueff=8 eV is applied. The calculated refraction index of M’-GdTaO4 is 224 which is in good agreement with the result abtained from the Gladstone-Dale relation.
Theoretical study on solvent effect of the molecular first hyperpolarizability
Authors: Zhu Jing  , Lü Chang-Gui  , Hong Xu-Sheng  , Cui Yi-Ping  ,   东南大学电子科学与工程学院先进光子学中心，南京 210096
Published: December 2020

second-order nonlinearity, solvent effect, harmonic oscillator
Effects of melt spinning process on microstructure and thermoelectric properties of n-type InSb compounds
Authors: Su Xian-Li  , Tang Xin-Feng  , Li Han  ,   武汉理工大学材料复合新技术国家重点实验室，武汉  430070
Published: December 2020

The single-phase InSb compounds have been prepared by novel melt spinning (MS) technique combined with spark plasma sintering (SPS) method, and the effects of melt spinning process on their microstructure and thermoelectric transport properties have been investigated. The results show that the free surface of ribbon obtained by MS consists of cubic grains with the size of 03—20 μm, and the contact surface of ribbon obtained by MS amorphous-like phases or finer nanostructures have formed, and after SPS the highly dense bulk material with lots of fine layered nanostructure has been obtained of about 40 nm in dimensions. By comparing the bulk InSb material prepared by melting method combined with SPS (Melt+SPS sample) with the bulk InSb material obtained by melting method combined with MS and SPS (Melt+MS+SPS sample)， we see that the MS process leads to a slight decrease in electrical conductivity, and an obvious increase in Seebeck coefficient, as well as a remarkable decrease in thermal conductivity and lattice thermal conductivity for bulk InSb in the testing temperature range of 300—700 K. At 300 K and 700 K, the lattice thermal conductivities of Melt+SPS sample and Melt+MS+SPS sample decrease by the scopes of 106% and 1664%, respectively. As a result, the maximum dimensionless figure of merit ZT of 0.49 is obtained at 700 K for the Melt+MS+SPS sample. Compared with that of Melt+SPS sample, it is increased by 29% at the same temperature.
Determination of the atmospheric aerosol optical density by multi axis differential optical absorption spectroscopy
Authors: Si Fu-Qi  , Xie Pin-Hua  , Dou Ke  , Zhan Kai  , Liu Yu  , Xu Jin  , Liu Wen-Qing  ,   中国科学院安徽光学精密机械研究所，中国科学院环境光学与技术重点实验室，合肥  230031
Published: December 2020

In this work, a method to determine atmospheric aerosol optical density from multi axis differential optical absorption spectroscopy (MAX-DOAS) observations was described. It basically utilizes the differential absorption structures of the oxygen collision complex (O4) in the UV and visible wavelength regions to derive information on aerosol optical properties. Based on radiative transfer model with appropriate aerosol single scattering albedo, asymmetry parameter and profile, atmospheric aerosol optical density was retrieved in an iterative process by comparison with measured O4 slant column densities at 360 nm. The retrieved value was verified through comparisons with sun photometer CE318.
The reconstruction of cardiac current dipole array based on cardiac magnetic signals and the studies on its relative characteristics
Authors: Wang Qian  , Ma Ping  , Hua Ning  , Lu Hong  , Tang Xue-Zheng  , Tang Fa-Kuan  ,   (1)北京大学物理学院，人工微结构和介观物理国家重点实验室，北京 100871; (2)北京大学物理学院，人工微结构和介观物理国家重点实验室，北京 100871；中国人民解放军第309医院心内科，北京 100091; (3)中国人民解放军第309医院心内科，北京 100091
Published: December 2020

Superconducting quantum interference device (SQUID) can detect weak cardiac magnetic signals. By analyzing those detected cardiac magnetic signals can we provide the evidence for the diagnosis of cardiac diseases. In this paper, we reconstruct the cardiac current dipole array using minimum-norm least-squares method (MNLS), thus realize the imaging of equivalent cardiac current sources. In the process of doing inverse computation using MNLS for current dipole array reconstruction, we assume that the cardiac current sources are distributed in a plane layer in human heart and the cardiac magnetic signals needed for inverse computation are obtained with three methods: the simulation based on single current dipole and current multipole models, and the realistic measurements by SQUID. Using the three methods for obtaining the cardiac magnetic signals, we discuss the distributive characteristics of current dipoles from the inverse computation. Besides, we also add the constant noise and random noise to the cardiac magnetic signals and consider their influences on the reconstruction of current dipole array.
Analysis of a typical internal charging induced spacecraft anomaly
Authors: Huang Jian-Guo  , Han Jian-Wei  ,   中国科学院空间科学与应用研究中心，北京  100190
Published: December 2020

Internal charging is generated by penetrative electrons from the outer radiation belt, and the resultant discharges usually occur inside spacecrafts or sdeeply in the surface dielectrics. Therefore it may produce more serious results in electronics on board compared with surface charging. In this article, the general characteristics of internal charging were introduced, and, as an example, an internal charging induced anomaly, which took place on Double Star (TC-1 and TC-2) was analyzed through correlation of the anomaly with high energetic electron enhancement. The analysis provides a typical instance for spacecraft anomaly diagnostics.
Study on the optical bistability in the laser oscillation of Yb doped vanadate crystals
Authors: Liu Jun-Hai  , Wan Yong  , Han Wen-Juan  , Yang Hong-Wei  , Zhang Huai-Jin  , Wang Ji-Yang  , Petrov Valentin  ,   (1)Max-Born-Institute for Nonlinear Optics and Ultrafast Spectroscopy,2A Max-Born-Str.,D-12489 Berlin,Germany; (2)青岛大学物理科学学院，青岛  266071; (3)山东大学晶体材料国家重点实验室，济南  250100
Published: December 2020

We have studied the effect of optical bistability exhibited in the laser oscillation of Yb:LuVO4, Yb:YVO4, and Yb:GdVO4, the three Yb doped vanadate crystals. The bistability range can be in excess of 1 W in terms of the pump power absorbed by the crystal. At the high-power-end side of the bistability region, i.e., the upper threshold for laser oscillation, discontinuous growing in the output power takes place, along with large fluctuations in the laser intensity occurring on sub-millisecond time scale. It is found that the bistability effect is affected significantly by the output coupling of the resonator, the crystal thickness, and the thermal effect existing in the crystal.
Experimental research on frequency doubling in periodically poled KTiOPO4 waveguide fabricated by femtosecond laser
Authors: Wang Jue  , Tu Cheng-Hou  , Zhang Shuang-Gen  , Lü Fu-Yun  ,   南开大学物理科学学院,天津  300071
Published: December 2020

We present in this paper the fabrication and characterization of type II waveguide in c-cut periodically poled KTiOPO4 crystal. The waveguide was fabricated by using a femtosecond laser，and the fabrication process was optimized. In our experiments single mode propagation was observed at optimal waveguide width of 145 μm and quasi-phase matching wavelength of 1064 nm. The second-harmonic conversion efficiency of 398% can be achieved.
Effect of laser polarization direction on high order harmonic generation of oxygen molecule——A simulation via TDDFT
Authors: Cui Lei  , Wang Xiao-Juan  , Wang Fan  , Zeng Xiang-Hua  ,   (1)常熟理工学院,常熟  215500; (2)宿迁学院基础部，宿迁  223800; (3)扬州大学物理科学与技术学院,扬州  225002
Published: December 2020

The high order harmonic generation (HHG) of O2 radiated by ultra-strong femto-second pulsed laser beam is simulated by the time dependent density functional theory (TDDFT) method with the general gradient approximation (GGA) of the exchange-correlation energy. The effect of different laser polarization directions on HHG is discussed. The results indicate that the HHG spectrum of O2 has the similar characteristic as the typical atom HHG spectrum. The HHG yields peaks when the molecules are aligned at about 45° from the polarization axis. Good agreements are found with the experiment.
Steering of nonlocal optical soliton in rectangular boundary lead glass
Authors: Jiang Qun  , Shou Qian  , Zheng Ya-Jian  , Liang Yan-Bin  , Hu Wei  , Guo Qi  ,   华南师范大学光子信息技术广东省高校重点实验室，广州  510006
Published: December 2020

We studied the steering of the nonlocal spatical optical soliton in thermal optical nonlinear lead glass theoretically and experimentally. By employing the conformal mapping method, the response function of the lead glass was obtained, and the influence of the boundary on the response function is discussed. Then we obtained the trajectory for the off-center soliton and the output displacement equation when the point of incidence is varied. We also observed experimentally the phenomenon of steering of the optical soliton in lead glass whose boundary shape is rectangular. The theoretical results are in good agreement with the experimental observations.
The experimental investigation of the discrete mode in the zero-average-refractive-index gap
Authors: Zhang Hui  , Li You-Quan  , Fu Yun-Qi  , Yuan Nai-Chang  ,   国防科学技术大学电子科学与工程学院，长沙  410073
Published: December 2020

We experimentally investigate the discrete mode in the zero-average-refractive-index gap (the zero-n—gap) of the one-dimensional periodical structures containing left-handed materials (LHMs) and right-handed materials (RHMs). When the discrete mode conditions are satisfied in the zero-n gap, there are no discrete propagating modes, but the zero-n—gap completely vanishes. This behavior is attributed to the dispersive property of LHMs and RHMs. In addition, the theoretical expectation of the discrete modes with no sidelobes in the zero-n—gap never occurs in experiment because the LHMs is intrinsically dispersive.