bluuebunny/crossref_metadata_2025 huggingface dataset:
Swap operation in a two-qubit anisotropy XYZ model in the presence of an inhomogeneous magnetic field
Authors: Zhang Guo-Feng  , Xing Zhao  ,   北京航空航天大学物理科学与核能工程学院物理系，北京  100191
Published: December 2020

Spin model plays an important role in the realization of quantum information processing. Quantum entanglement can be constructed, also （swap）n quantum logic gate is available if anisotropy is ignored, when Heisenberg interaction between spins is used; thus a complete quantum computing gate will be realized by combining single-qubit rotation gate. To study the influence of anisotropy on logic gate has high academic value since anisotropy is inevitable in any solid material. In this paper, swap operation in a two-qubit anisotropy XYZ model in the presence of an inhomogeneous magnetic field is discussed. The swap errors caused by the anisotropy parameter ν of the exchange interaction between spins and the inhomogeneous field δ are evaluated. We can see clearly when the swap operation can be approximately used as an ideal swap gate.
Effects of next-nearest-neighbor interactions on the dynamics of random quantum Ising model
Authors: Yuan Xiao-Juan  , Zhao Bang-Yu  , Chen Shu-Xia  , Kong Xiang-Mu  ,   (1)积成电子股份有限公司，济南 250100; (2)山东省激光偏光与信息技术重点实验室，曲阜师范大学物理工程学院，曲阜 273165; (3)山东省激光偏光与信息技术重点实验室，曲阜师范大学物理工程学院，曲阜 273165；山东大学物理学院，晶体材料国家重点实验室，经济 250100
Published: December 2020

The dynamics of one-dimensional random quantum Ising model with both nearest-neighbor and next-nearest-neighbor （NNN） interactions is investigated in the high temperature limit by the method of recurrence relations. Spin autocorrelations and the corresponding spectral densities of the system are calculated. Supposing that the exchange couplings （or the transverse fields） satisfy the double-Gaussian distribution, the effects of this distribution on the dynamics of the system is studied. The results show that the dynamics of the system undergoes a crossover from a collective-mode behavior to a central-peak one when the standard deviations σJ（or σB）of the random variables are small and there is no crossover when σJ（or σB）are large. Meanwhile, the effects of NNN interactions on the dynamics of the system are studied. It is found that the central-peak behavior becomes more obvious and the collective-mode behavior becomes weaker as Ki increase, especially when Ki>Ji/2（Ji and Ki are exchange couplings of the NN and NNN interactions, respectively）. However, the effects are small when the NNN interactions are weak （KiJi/2）.
Color image degradation algorithms based on Z-matrix map and selective encryption
Authors: Zhao Liang  , Liao Xiao-Feng  , Xiang Tao  , Xiao Di  ,   重庆大学计算机学院，重庆  400044
Published: December 2020

With the development of information technology and network, multimedia protection has become a major concern, in which images are the important research objects. Especially, the image degradation is one of basic fields. This paper introduces a three-dimensional Z-matrix map which can be used for encryption, and shows its satisfactory property. Then, two color image degradation algorithms based on different templates for selective encryption are proposed. Finally, the performance and security of them are analyzed. Simulation results indicate the reliability of these schemes.
Controlling fractional-order new chaotic system based on Lyapunov equation
Authors: Xu Zhe  , Liu Chong-Xin  , Yang Tao  ,   西安交通大学电气工程学院，电力设备电气绝缘国家重点实验室，西安  710049
Published: December 2020

A new circuit unit for the analysis and synthesis of the chaotic behaviors in the new fractional-order system is proposed in this paper. Based on the approximation theory of fractional-order operator, an electronic circuit is designed to demonstrate the dynamic behaviors of the fractional-order Liu system with α=09 An effective controller is designed based on a theory of stability identification based on Lyapunov equation. The results between simulation and experiment are in good agreement, thereby proving the existence of chaos in the fractional-order new system and the effectiveness of our proposed control method.
Generalized synchronization of two different unidirectional coupled Lorenz systems
Authors: Li Xiao-Juan  , Xu Zhen-Yuan  , Xie Qing-Chun  , Wang Bing  ,   江南大学理学院，数学系，无锡  214122
Published: December 2020

The generalized synchronization （GS） of two different unidirectional coupled Lorenz systems is studied. According to the method of auxiliary-system, by using the theories of stability and the boundary of the responsed system, a sufficient criterion is rigorously proven. Furthermore, based on the modified system approach, GS is classified into three types, the first type,the second type and the third type of GS when the modified system has an asymptotically stable equilibrium of zero solution, asymptotically stable equilibrium of non-zero solution, asymptotically stable limit cycles, respectively. Moreover, using the Routh-Hurwitz theorem to analyze the stability of equilibrium of the modified system, the existence of the first type and the second type of GS are strictly theoretically proved. Numerical simulations show the effectiveness of the method.
Synchronization of fractional-order unified chaotic system via linear control
Authors: Zhang Ruo-Xun  , Yang Shi-Ping  , Liu Yong-Li  ,   (1)河北师范大学物理科学与信息工程学院，石家庄  050016；河北省新型薄膜材料实验室，石家庄  050016; (2)河北师范大学物理科学与信息工程学院，石家庄  050016；河北省新型薄膜材料实验室，石家庄  050016；邢台学院初等教育学院 ，邢台  054001; (3)邢台学院初等教育学院 ，邢台  054001
Published: December 2020

Chaos synchronization in fractional-order unified chaotic system is disscussed in this paper. Based on the stability theory of fractional-order system, the control law is presented to achieve chaos synchronization. The advantage of the proposed controllers is that they are linear and have lower dimensions than that of the states. With this technique it is very easy to find the suitable feedback constant. Simulation results for fractional-order Lorenz, Lü and Chen chaotic systems are provided to illustrate the effectiveness of the proposed scheme.
Chattering bifurcations in a Duffing unilateral vibro-impact system
Authors: Feng Jin-Qian  , Xu Wei  , Niu Yu-Jun  ,   (1)西北工业大学理学院应用数学系，西安  710072; (2)西北工业大学理学院应用数学系，西安  710072；西安工程大学理学院，西安  170048
Published: December 2020

A tail-mapping is introduced to deal with the tail impacts caused by the chattering，and based on which，an effective numerical method is suggested to simulate the chattering in the vibro-impact system. As an illustrative example，a Duffing unilateral vibro-impact system is investigated. The results show the evidence of complete and incomplete chattering. We also investigate two novel chattering bifurcations，including transitions from complete to incomplete chattering and incomplete chattering period to aperiodic motion.
Dynamic analysis of the fractional order Newton-Leipnik system
Authors: Wang Ming-Jun  , Wang Xing-Yuan  ,   大连理工大学电子与信息工程学院，大连  116024
Published: December 2020

Based on the stability theory of fractional order linear systems, the dynamic behavior of the fractional order Newton-Leipnik system with double attractor is studied. Our research shows that the fractional order Newton-Leipnik system involves reverse Hopf bifurcation course, i.e., with the decrease of fractional order, the fractional order Newton-Leipnik system shows mutation from double attractor to single attractor, the dynamic behavior experiences chaos, transient period and converges to one stable equilibrium.
The study of network motifs induced from discrete time series
Authors: Dong Zhao  , Li Xiang  ,   复旦大学电子工程系，上海  200433
Published: December 2020

Complex network theory is used to characterize the temporal and phase space features of a time series when it is transferred into a network. In this paper, we study the motif ranks of complex networks induced from different categories of time series with periodic bifurcations and chaos, which are generated with two algorithms: the Visiblity Graph （VG） algorithm and the Phase-space Reconstruction （PR） algorithm. The advantages of both algorithms are analyzed.
Force control of uncertain robot based on the passivity
Authors: Wen Shu-Huan  , Yuan Jun-Ying  ,   燕山大学电气工程学院，工业计算机控制工程河北省重点实验室,秦皇岛 066004
Published: December 2020

According to the theory of passivity, the force control on the robot system is studied from a relatively new perspective. In general, a strictly passive dynamic system has a good dynamic characteristics and robustness. Therefore, a passive approach to force control is presented in the force controller design. In view of the uncertainty and environmental impacts in robot modeling, the paper adds a compensation term to compensate for model uncertainty in force control loop. The simulation results show that this control program enhances the dynamic performance and robustness of the system.
Fabrication and performance of CVD diamond radiation detector
Authors: Zhou Hai-Yang  , Zhu Xiao-Dong  , Zhan Ru-Juan  ,   中国科学院基础等离子体物理重点实验室，中国科学技术大学物理学院近代物理系，合肥  230026
Published: December 2020

Radiation detector of high performance was fabricated using free-standing thick CVD diamond films. The CVD diamond detector has “cross-finger” coplanar electrodes. The electrical contact between electrodes and diamond films is ohmic. The effective area is 3×3 mm2. When working under electric field strength of 30 kV/cm, the dark current of the detector is only about 01 nA, the rise time of the signal is about 590 ps, its sensitivity is about 110 mA/W. Besides, the detector has fairly good linearity on dose rate.
Analysis of high brightness laser synchrotron source based on the technique of oval supercavity
Authors: Meng Xian-Zhu  , Wang Ming-Hong  , Ren Zhong-Min  ,   聊城大学物理科学与信息工程学院,聊城  252059
Published: December 2020

The novel technical scheme of oval supercavity is presented. The light intensity in focus of oval supercavity are computed. By using the Compton scattering theory, the high brightness laser synchrotron source based on the technique of oval supercavity, including photon yield and radiant power, are calculated and discussed. The results show that when the reflectivity of oval supercavity mirror is equal to 99.99%, the light intensity in focus of oval supercavity is about 5000 times higher than that of the incident intensity （I0）. the γ-ray with energy up to 10975 MeV are expected to be produced by Compton vertical scattering of laser photons on the 3.5 GeV electron bunches, the photon yield and the radiant power of Compton vertical scattering between electron bunches and laser beam in focus of oval supercavity is about 25×107 times higher than that of Compton vertical scattering between electron bunches and single laser beam.
The implementation of the computer simulation of magnetically insulated transmission lines in post-hole convolute
Authors: Liu La-Qun  , Meng Lin  , Deng Jian-Jun  , Song Sheng-Yi  , Zou Wen-Kang  , Liu Da-Gang  , Liu Sheng-Gang  ,   (1)电子科技大学物理电子学院，成都  610054; (2)中国工程物理研究院流体物理研究所 ，绵阳  621900
Published: December 2020

This paper presents the formation of the magnetic insulation and the basic principles of its computer simulation. This paper uses the non-uniform grid model successfully to fulfill the requiremet of three-dimensional simulation modeling of the double post-hole convolute whose structures are complex. By using the metallic struts to realize the load modeling of the computer implementation, we explored the feasibility of applying the MPI parallel algorith in the simulation. Finally the simulation results are checked by using the double post-hole convolute of vacuum section of the Z accelerator as an example.
The molecular orientation and electronic structure of 3, 4, 9, 10-perylene tetracarboxylic dianhydride grown on Au(111)
Authors: Cao Liang  , Zhang Wen-Hua  , Chen Tie-Xin  , Han Yu-Yan  , Xu Fa-Qiang  , Zhu Jun-Fa  , Yan Wen-Sheng  , Xu Yang  , Wang Feng  ,   中国科学技术大学国家同步辐射实验室，核科学技术学院，合肥  230029
Published: December 2020

The interface electronic structure, molecular orientation and surface morphology of the organic semiconductor 3,4,9,10-perylene tetracarboxylic dianhydride （PTCDA） grown on Au （111） surface have been studied by means of X-ray photoelectron spectroscopy （XPS）, synchrotron radiation ultraviolet photoelectron spectroscopy （SRUPS）, near edge X-ray absorption fine structure spectroscopy （NEXAFS） and atomic force microscopy （AFM）. It can be seen from the SRUPS results that the Shockley-type Au （111） surface state near the Fermi level extinguishes immediately after sub-monolayer of PTCDA is deposited onto the Au surface without the emergence of interface hybrid state. This indicates that a charge transfer process takes place at the interface between PTCDA molecule and Au（111）, but does not lead to strong chemical reaction. Angle dependent NEXAFS and SRUPS show that the PTCDA overlayers are ordered and the molecules lie flatly on the Au（111） surface. According to the AFM images and the evolution of Au 4f7/2 and C 1s integral intensities with increasing film thickness, the typical Stranski- Krastanov growth mode is proposed for PTCDA deposition on Au（111） surface, that is, layer by layer growth followed by island growth mode. The Dewetting transition occurs between the 2D and 3D growth modes.
Theoretical study on the partial wave cross sections of vibrational and rotational excitation for the collisions of He isotope with H2
Authors: Wang Xiao-Lu  , Xu Mei  , Linghu Rong-Feng  , Sun Ke-Bin  , Yang Xiang-Dong  ,   (1)贵州师范大学物理与电子科学学院，贵阳 550001; (2)四川大学原子与分子物理研究所，成都 610065; (3)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

In this paper, the close-coupling method and the Tang-Toennies potential are applied to the collisions of 3He,4He,9He and 10He with H2 systems when the incident energy is 07 eV. The vibrational and rotational excitation cross sections are calculated. By analyzing the partial wave cross sections, the changing tendencies of the partial wave cross sections with the quantum number and reduced mass in the isotopic substitution systems are obtained.
Triple differential cross sections of the （e, 2e） reaction for electron impact Ar in a coplanar asymmetric geometry
Authors: Gao Rui-Jun  , Ge Zi-Ming  ,   华东理工大学理学院物理系，上海 200237
Published: December 2020

The triple differential cross section for Ar（3p6） in the special geometry of coplanar large energy loss and close to minimum momentum transfer has been calculated with the modified distorted wave Born approximation （DWBA）. The polarization interaction between the electron and the target, especially in the near-target region, and the post-collision interactions are included in the calculation. The theoretical results with modified DWBA are compared with the recent experimental data, the standard DWBA and DWBA-G. It is shown that the polarization are very important in the calculation of TDCS in coplanar asymmetric （e,2e） reaction.
Design of a high current density cylindrical electron optics system
Authors: Sun Fu-Yu  , Wu Zhen-Hua  , Zhang Kai-Chun  ,   电子科技大学物理电子学院太赫兹研究中心，成都  610054
Published: December 2020

A high current density cylindrical electron optics system is designed for extended interaction oscillator, including the design of electron gun and focusing magnetic field. To obtain good beam properties, a theory of ideal circular beam focusing is used in design. The focusing magnetic field is calculated by balancing the radial forces. CST PARTICLE STUDIO simulation under space-charge-limited emission model shows good beam qualities with a parallel beam flow throughout the gun and interaction sections. The simulation result is in good agreement with design theory, the beam mean current density attains 244 A/cm2, fill factor 767%, beam transmission 100%.
Ocean duct inversion from radar clutter using variation adjoint and regularization method (Ⅰ): Theoretical part
Authors: Sheng Zheng  , Huang Si-Xun  ,   解放军理工大学气象学院，南京  211101
Published: December 2020

Since the traditional anti-statistical algorithms in the inversion of refractivity from radar clutter （RFC） need too much calculation, a new physical algorithm （variation adjoint combined with the regularization method） is proposed instead. In the variation adjoint method, the tangent model, adjoint equations and accompanying boundary conditions, the solving expression of adjoint equations, and the mathematical functional expression of the gradient were derived respectively, and the problem of how to coordinate functional gradient of the complex equations is solved. In the regularization method, to take into account the characteristics of radar electromagnetic wave propagation, we choose a suitable regularization term to solve the inversion of the ill-posed problems. Finally, the implementation of the iterative inversion algorithm was derived.
Study of random sample scattering phase functions of polydisperse atmospheric aerosol in ultraviolet band
Authors: Bai Lu  , Tang Shuang-Qing  , Wu Zhen-Sen  , Xie Pin-Hua  , Wang Shi-Mei  ,   (1)西安电子科技大学理学院，西安 710071; (2)中国科学院安徽光学精密机械研究所环境光学与技术重点实验室，合肥 230031
Published: December 2020

Based on the basic theory of electromagnetic scattering and radiation transmission, the scattering phase functions of various kinds of atmospheric aerosol with special distributions in typical UV band are presented. A direct sample method has been used to simulate the discrete polydisperse Mie phase functions of haze aerosol. Comparisons are made between the Henyey-Greenstein phase function, the modified Henyey-Greenstein phase function, the direct sample phase function presented in this paper and the polydisperse Mie phase function. The influence of different scattering phase function simulation methods on radiative transfer properties has been studied by using the Monte Carlo method. Numerical results showed that the rigorous simulation of scattering phase function is of importance in radiative transfer problems.
Husimi function and Wehrl entropy in thermo field dynamics
Authors: Wang Shuai  , Zhang Bing-Yun  , Zhang Yun-Hai  ,   菏泽学院物理系,菏泽 274015
Published: December 2020

Using the quantum phase space technique and the information-theory like the Wehrl entropy, the Husimi function and the Wehrl entropy of the quantum pure states and the corresponding mixed states in thermo field dynamics are studied. It is found that the Husimi function and the Wehrl entropy of the thermal coherent state agree with that of the corresponding mixed states. And the Wehrl entropy of thermal coherent state is not related with the displacement factor. Therefore for a quantum system, the quantum fluctuations of the observable quantities and corresponding uncertainty relation are also not related with the displacement factor in the thermal coherent state.
Application of lattice Boltzmann method to phase transition process
Authors: Zeng Jian-Bang  , Li Long-Jian  , Liao Quan  , Chen Qing-Hua  , Cui Wen-Zhi  , Pan Liang-Ming  ,   重庆大学动力工程学院，重庆  400030
Published: December 2020

In this paper，a new single-component lattice Boltzmann method is proposed to describe liquid-vapor phase transition process. Water and ammonia phase transition process are simulated by using this new model for Redlich-Kwong，Redlich-Kwong Soave and Peng-Robinson equations of state. Compared with the experimental data of water and ammonia，the results show that the Peng-Robinson equation of state is more suitable to describe the phase transitions process of water，ammonia and other substance. In particularly，the simulation results of ammonia with Peng-Robinson equation of state are more close to the experimental data. In order to demonstrate the capability of this model for dealing with two-phase problems，the mass density profile across the interface of water or ammonia which is controlled by Peng-Robinson equation of state are simulated by this model for different temperatures. These simulation results agree with that of classical interface theory. Finally，the relationship between the bubble (droplet) inside and outside pressure difference and its radius is simulated when the bubble (droplet) is in equilibrium environment at different temperatures. The results agree with Laplace law. The surface tension of water and ammonia is obtained from simulation results at different temperature，which agree with experimental data and the critical theory of surface tension.
Theoretical study of the second-order nonlinear optical properties of one- and two-dimensional charge transfer molecules in solvents
Authors: Li Ming-Xue  , Han Kui  , Li Hai-Peng  , Huang Zhi-Min  , Zhong Qi  , Tong Xing  , Wu Qiong-Hua  ,   中国矿业大学理学院物理系，徐州 221116
Published: December 2020

The solvent-dependent and frequency-dependent nonlinear optical （NLO） properties of one-dimensional charge transfer （1DCT） molecule, p-nitroaniline （pNA） and two-dimensional charge transfer （2DCT） molecule, 1,3-diamino-4,6- dinitrobenzen （DADB） have been studied by using the density functional theory （DFT） and time-dependent coupled perturbed Hartree-Fork （TDHF） method, respectively. The reasons of the influence of the solvent polarity and incident light frequency on the NLO properties for 1DCT and 2DCT molecules were also discussed. Theoretical results demonstrate that the first hyperpolarizability β and ultraviolet spectra strongly depend on the dielectric constant ε of solvent, but solvent polarity has little effect on the anisotropy ratio η and depolarization ratio D due to the linear relationship between ︱βxxy︱ and ︱βyyy︱ with the increase of the solvent dielectric constant ε. In addition, the incident frequency has a great influence on β,η and D . It is found that the solvent effect and the frequency dispersion effect should be considered in calculations for obtaining accurate results.
Deflection characteristics of incoherent coupled bright and dark photovoltaic spatial soliton pairs
Authors: Cui Hu  , Zhang Bing-Zhi  , She Wei-Long  ,   (1)中山大学光电材料与技术国家重点实验室，广州  510275; (2)中山大学光电材料与技术国家重点实验室，广州  510275；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  510631
Published: December 2020

We numerically investigate the deflection characteristics of incoherent coupled bright and dark photovoltaic spatial soliton pairs in a photovoltaic photorefractive crystal with diffusion effect. The numerical results show that, owing to the incoherent interaction, a bright soliton and a dark soliton in the crystal trap each other and the centers of the two solitons move along the same trajectory. It is found that, the deflection of the bright soliton can be controlled by adjusting the input background intensity of the dark soliton when the input peak intensity of the bright soliton is fixed; and the deflection of the bright soliton is suppressed when the input background intensity of the dark soliton is at a special value, while the bright soliton undergoes a deflection when the input background intensity of the dark soliton deviates from this special value. Also, the deflection of the dark soliton can be controlled by adjusting the input peak intensity of the bright soliton when the input background intensity of the dark soliton is fixed.
Diffraction and properties of holographic polymer dispersed liquid crystal switchable lens
Authors: Zheng Ji-Hong  , Zhong Yang-Wan  , Wen Ken  , Luo Xin-Sheng  , Zhuang Song-Lin  ,   (1)江西理工大学信息工程学院,赣州  341000; (2)上海理工大学上海市现代光学重点实验室，上海  200093
Published: December 2020

A holographic polymer dispersed liquid crystal （H-PDLC） switchable lens is reported. The diffraction efficiency was analyzed at different phase separation coefficients within the visible band （400—800 nm） with the coupled wave theory for a phase-type H-PDLC switchable lens. In our experiments, the maximum efficency of 70% was achieved. The H-PDLC switchable lens shows excellent imaging performance and fast response.It is potentially useful in many applications, such as optical communications, optical imaging,e.g.,in digital cameras.
Experimental verification of left-handed metamaterials composed of electric and magnetic resonators
Authors: Wang Jia-Fu  , Qu Shao-Bo  , Xu Zhuo  , Xia Song  , Zhang Jie-Qiu  , Ma Hua  , Yang Yi-Ming  , Wu Xiang  ,   (1)空军工程大学理学院，西安 710051; (2)空军工程大学理学院，西安 710051；西安交通大学电子陶瓷与器件教育部重点实验室，西安 710049; (3)西安交通大学电子陶瓷与器件教育部重点实验室，西安 710049
Published: December 2020

Left-handed metamaterials were fabricated and tested. As the first step in the test, the transmission spectra of electric resonator array and magnetic resonator array were measured, from which their respective negative parameter regions can be determined. Then, the transmission spectra of the left-handed metamaterial composed of electric and magnetic resonators were obtained. From the measured scattering parameters, effective permittivity and permeability can be retrieved. The experiment results show that there is a pass-band in the overlapping region where there is a respective stop-band for both the electric and magnetic arrays. In this pass-band, both the effective permittivity and permeability are negative, which verifies the validity of left-handed metamaterials composed of electric and magnetic resonators.
The effect of dispersion on FM-AM coversion in high power laser front end
Authors: Huang Xiao-Dong  , Zhang Xiao-Min  , Wang Jian-Jun  , Xu Dang-Peng  , Zhang Rui  , Lin Hong-Huan  , Deng Ying  , Geng Yuan-Chao  , Yu Xiao-Qiu  ,   (1)中国工程物理研究院激光聚变研究中心，绵阳 621900; (2)中国工程物理研究院激光聚变研究中心，绵阳 621900；山东大学光学工程系，济南 251000
Published: December 2020

Sinusoidal phase modulated pulse could provide broad bandwidth and high modulation frequency for spectral dispersion method in high power laser driver system. Phase modulation could be converted to intensity modulation due to dispersion during the pulse propagation in the fiber,and the intensity modulation enhances the nonlinear effect in the large-mode-area double-clad fiber amplifier and make the spectral controlling more difficult. 2 GHz and 1425 GHz phase modulation pulses propagated in fibers with different lengths were measured, and based on the dispersion model in the fiber, theoretical analysis shows good similarity between simulation and experimental results for the 2 GHz phase modulation pulse.
Dissipative-soliton mode locked laser based on large-mode-area photonic crystal fiber
Authors: Zhang Xin  , Hu Ming-Lie  , Song You-Jian  , Chai Lu  , Wang Qing-Yue  ,   天津大学精密仪器与光电子工程学院，光电信息技术科学教育部重点实验室，天津   300072
Published: December 2020

A dissipative-soliton mode locked laser based on Yb-doped single polarization large-mode-area photonic crystal fiber is demonstrated. The dissipative soliton dynamics is explored by numerical simulation. Compared with all normal dispersion fiber lasers, there are more pulse shaping mechanisms in a dissipative-soliton fiber laser, including the nonlinear absorption of SESAM, spectrum filtering of the chirped pulse and gain dispersion, which results in robust and stable operation. Among them, spectrum filtering plays a dominant role in mode-locking, it shapes pulse both in frequency domain and time domain and keeps the pulse duration below 1 ps in the cavity. For the first time, sub-1 ps pulse is directly generated in a dispersion compensation free cavity. The fiber laser directly generates 777 fs pulse at 1 W average power at a repetition rate of 514 MHz, corresponding to a single pulse energy of 20 nJ.
Numerical simulation on segregation process of particles using 3D discrete element method
Authors: Zhao La-La  , Liu Chu-Sheng  , Yan Jun-Xia  , Xu Zhi-Peng  ,   中国矿业大学机电工程学院，徐州  221116
Published: December 2020

Basing on dry contact model of soft spheres the segregation processes of spherical and non-spherical particles were simulated using threes-dimensional discrete element methods（DEM）. Particle segregation mechanism was analyzed in view of force, torque and energy conversion between particles. Influence of segregation speed affected by particle size ratio was also discussed. The result shows that large particles are more active than small ones in segregation process, and non-spherical particles have higher energy, which makes up the influence of particle shape to segregation process to some extent, are more active than spherical particles. Average normal force, tangential force between large particles, their torque and kinetic energy are all greater than those of small particles. Particle segregation speed increases significantly with the increasing of size ratio. When the size ratio is greater than the critical value 3, the amplitude of increase in segregation speed will be slowed down.
Direct numerical simulation of the sedimentation of two particles with thermal convection
Authors: Liu Han-Tao  , Chang Jian-Zhong  , An Kang  , Su Tie-Xiong  ,   中北大学能源环境工程与计算流体力学实验室，太原 030051
Published: December 2020

Based on the study of isothermal inert particle sedimentation, the Arbitrary Lagrangian-Eulerian technique was used to solve the problem of sedimentation of two solid particles with thermal convection, including the energy equation. The results show that because of the dynamic wake caused by thermal convection, the trajectory of particles are distinct from each other when settling in isothermal, cool and hot fluid; there is vortex shedding in hot fluid, while in cool fluid a strong upward thermal plume forms.
Further theoretical study on laminar-flow equilibria in magnetically focused relativistic electron beams
Authors: Liu Jing  , Shu Ting  , Li Zhi-Qiang  ,   国防科技大学光电科学与工程学院，长沙  410073
Published: December 2020

A numerical solution for the self-consistent differential equations describing the laminar-flow equilibrium in magnetically focused relativistic electron beams is given and proved to be available by comparison with analytical results of solid electron beam in the case of pθ=0 （magnetically shielded sources）. With the numerical method, the space-charge limited current and the externally applied magnetic field of both solid and annular electron beam in three cases of pθ=0,pθ=const and pθ∝r2 （magnetically immerged sources） are presented and compared. It is shown that the conditions at the source with respect to the canonical angular momentum pθ have little effect on the space-charge limited current and the externally applied magnetic field, but more intense annular electron beam generated by the source with pθ=const. can be transported in the same drift tube under lower guided magnetic field than solid ones.
The Bohm criterion for a collisional plasma sheath in an oblique magnetic field
Authors: Zou Xiu  , Ji Yan-Kun  , Zou Bin-Yan  ,   大连交通大学理学院，大连 116028
Published: December 2020

The Bohm criterion for a collisinal plasma sheath in an oblique magnetic field is investigated with a two-fluid model. It is shown that the upper and lower limits for the sheath criterion exist. And the range of the ion Mach number depends on the magnetic field and the incidence status of the ions.
Angular distribution measurement and simulation of M band X-ray from the half- hohlraum
Authors: Zhou Jin-Yu  , Huang Tian-Xuan  , Meng Lin  , Jiang Wei  ,   (1)电子科技大学物理电子学院，成都 610054; (2)中国工程物理研究院激光聚变中心，绵阳 621900; (3)中国工程物理研究院激光聚变中心，绵阳 621900；电子科技大学物理电子学院，成都 610054
Published: December 2020

Measurement of radiation field near a implosion pellet M band X-ray is a important area in ICF research. On the SG Ⅱ laser facility, M band X-ray from Au plasma was measured in half-hohlraum radiation from the end. The experimental set-up and typical result were given. And weve also used the view-factor program to simulate this experiment. The results indicate that angular distribution of M band X-ray from the end of half-hohlraum doesnt assume linear relationship with the cosine of eradiating angle. The results are useful for the research of implosion experiment and target design.
Study on the phase transition of the filaments structure in dielectric barrier discharge
Authors: Dong Li-Fang  , Yang Yu-Jie  , Fan Wei-Li  , Yue Han  , Wang Shuai  , Xiao Hong  ,   河北大学物理科学与技术学院，保定 071002
Published: December 2020

The evolution of filaments structure with the applied voltage and gas pressure in dielectric barrier discharge in argon/air mixture is studied, which is also analyzed in the aspect of two-dimensional phase transition. With the increase of the applied voltage, the filaments structure undergoes stages of sparse random filaments-dense random filaments-hexagon structure-hexagonal superlattice structure-chaos, which can be considered as a phase transition from gas-liquid-simple solid-superlattice solid-liquid. The changes of the lattice constant and the distance between two neighboring lattice points are investigated in the process of formation of the hexagonal superlattice structure in the phase transition. In addition, the formation of the large spots and the Penta-Hepta defects in the hexagonal superlattice structure are also studied.
Finite element method study on the temperature distribution in the cell of large single crystal diamond
Authors: Han Qi-Gang  , Ma Hong-An  , Xiao Hong-Yu  , Li Rui  , Zhang Cong  , Li Zhan-Chang  , Tian Yu  , Jia Xiao-Peng  ,   (1)长春理工大学材料科学与工程学院，长春 130012; (2)吉林大学超硬材料国家重点实验室，长春 130012
Published: December 2020

The temperature distribution in the cell of single crystal diamond grown by the temperature gradient method has been studied, which is based on the finite element method. Our results shwo that the temperature distribution in the synthetic process of single crystal diamond is not uniform. The highest temperature in the cell is located at the outside of single carbon solvent, and the lowest temperature in the cell is located near the diamond seed. The heat transfer and the mass transport have a same direction （from outside of carbon source to diamond seed）. The temperature gradient in the axial direction is higher than that in the radial direction, which explains why the size of synthetic single crystal diamond in the axial direction is larger than that in the radial direction. The model will be useful for the design of single crystal diamond grown by the temperature gradient method. Furthermore, this work will be hopeful to improve the cubic anvil type high pressure techniques for the synthesis of high quality diamond crystals.
Effect of electrical parameters on characteristics of microarc oxidation coatings of commercially pure titanium in colloid
Authors: Chen Gen-Yu  , Wu Han-Hua  , Li Yue  , Chang Hong  , Tang Yuan-Guang  ,   吉林大学应用物理系，长春  130021
Published: December 2020

The effects of the pulse voltage amplitude （U） and duty cycle （d） on the growth characteristics, microstructure, phase component and corrosion resistance of the coating formed by microarc oxidation （MAO） on commercially pure titanium substrates in colloid have been systematically studied. The results show that, with the increase of U or d, the coating thickness increases almost linearly, the pore size and the roughness of the surface increases gradually, while the pore density decreases. The coatings almost entirely consist of dense layer, and they are completely composed of rutile TiO2 except the one formed at the duty cycle of 10% （U=450 V）, which contains a small amount of anatase TiO2 The corrosion resistance test in sulfuric acid solution （30%） shows that the corrosion resistance of the samples is closely related to U and d, with the increase of U or d, the corrosion resistance of the samples increases gradually.
First-principles calculations for the structure and mechanical properties of PtN2
Authors: Li De-Hua  , Zhu Xiao-Ling  , Su Wen-Jin  , Cheng Xin-Lu  ,   (1)四川大学原子与分子物理研究所，成都  610064; (2)四川师范大学物理与电子工程学院，成都  610066
Published: December 2020

We employ ab initio plane-wave pseudopotential density functional theory to calculate the coordinates， equilibrium lattice parameters，bulk modulus，shear modulus and elastic constant of PtN2，and those calculated results agree well with the other experimental data and the published theoretical data. The curve of volume dependence of energy indicates the energy of STAAstructure is lower than that of pyrite structure. According to our result and the experimental criterion raised by Pugh, we come to the conclusion that the PtN2 is a very hard and fragile material. But when the pressure increases, the PtN2 becomes malleable gradually. It is revealed that the pyrite structure of the PtN2 is a semiconductor and the STAA structure of the PtN2 is a conductor by analyzing their density of states and band structure.
First-principles study on the band structure and optical properties of strained Ru2Si3 semiconductor
Authors: Cui Dong-Meng  , Xie Quan  , Chen Qian  , Zhao Feng-Juan  , Li Xu-Zhen  ,   贵州大学理学院，贵州大学新型光电子材料与技术研究所，贵阳 550025
Published: December 2020

We calculated the band structure, density of states and optical properties of semiconductor material Ru2Si3 epitaxial-grown on Ru2Si3 （100）//Si（001） with Ru2Si3［010］//Si［110］ by using the pseudo-potential plane wave method based on first principles methods. As shown by the calculated results, orthorhombic Ru2Si3 is not only a direct semiconductor with the band gap of 0773 eV, but also in stable condition when the lattice parameter a is 1093 nm.The valence bands of Ru2Si3 are mainly composed of Ru 4d and the conduction bands are mainly composed of Ru 3d and Si 3p. Its static dielectric function ε1（0） is 1891, the refractive index n0 is 4349
Studies on the full vibrational spectra and dissociation energies of some diatomic ions
Authors: Fan Qun-Chao  , Feng Hao  , Sun Wei-Guo  ,   (1)四川大学原子与分子物理研究所，成都  610065; (2)西华大学物理与化学学院，成都  610039
Published: December 2020

A parameter-free analytical formula for dissociation energy of diatomic system is suggested recently by Sun et al. Together with the algebraic method (AM) which was presented to obtain accurate full vibrational energies for diatomic molecules in their previous work，the new formula is applied to study the dissociation energies and the full vibrational spectra of some diatomic ions in this work. The results show that the AM vibrational spectra and dissociation energies have excellent agreement with experimental values.
Exact diagonalization solution of DNA model systems of limited grid
Authors: Huang Shu-Wen  , Liu Tao  , Wang Ke-Lin  ,   西南科技大学理学院,绵阳 621010
Published: December 2020

A exact diagonalization solution method for solving the one-dimensional Holstein model of DNA is discussed in this paper. We compared the results of this paper with the former results of coherent state variational method （CVM） to check the reliability and accuracy of CVM. It is clearly seen that the ground state energy calculated by exact diagonalization solution method is considerably smaller than that of the CVM and can reach the saturation with smaller site number. With the strict method we can not only obtain the ground state energy, but also the spectra of all excited states. Therefore there is a significant improvement in the studying of Holstein model than the former CVM .
Optical properties and crystallization of GeSe2-Sb2Se3-CsCl glasses
Authors: Shen Xiang  , Nie Qiu-Hua  , Xu Tie-Feng  , Dai Shi-Xun  , Wang Xun-Si  , Wu Li-Gang  ,   宁波大学信息科学与工程学院，宁波 315211
Published: December 2020

Chalcohalide glasses 20GeSe2-（80-x）Sb2Se3-xCsCl（x＝2，4，8，10 mol%）were synthesized by the conventional melt-quenching method. The optical transmission spectra were measured from the visible to the far-infrared range. The effect of CsCl content on the short-edged wavelength was investigated. Moreover，the differential thermal analysis curves of a typical 20GeSe2-76Sb2Se3-4CsCl glass were measured under different heating rates，and its crystallization kinetics was analyzed under the non-isothermal condition. The results show that，the introduction of CsCl into the glass lowers the non-bonding energy level，which leads to the increase of the electronic bandgap Eg，and blue-shift of the short edged wavelength. Compared with the conventional Johnson-Mehl-Avrami model，the autocatalytic model gives a better description of the kinetic process for the glass sample.
Investigation on memory effect of MOS capacitors with Al2O3/Pt-nanocrystals/HfO2
Authors: Huang Yue  , Gou Hong-Yan  , Liao Zhong-Wei  , Sun Qing-Qing  , Zhang Wei  , Ding Shi-Jin  ,   专用集成电路与系统国家重点实验室，复旦大学微电子研究院，上海  200433
Published: December 2020

Growth of Pt nanocrystals has been investigated by means of electron beam evaporation of Pt layer and post rapid thermal annealing. The results indicate that the density of nanocrystals increases first with the annealing temperature and the annealing time，followed by a slight decrease. Uniformly distributed nanocystals with a density of 30×1011 cm-2 can be obtained in the case of the annealing at 800℃ for 20 s. Further，memory effect of Al2O3/Pt nanocrystals/HfO2-based MOS capacitors has been characterized，indicating a capacitance-voltage （C-V） hysteresis window as large as 201 V in the sweep voltage range of -3—+8 V. In terms of the same programming time，the flat band voltage shift of the memory capacitor starts to increase remarkably when the programming voltage is increased to 9 V. This is related to a decrease in the energy barrier across the tunneling layer for electrons，i.e.，the tunnel mechanism of electrons is changed from direct tunneling to Fowler-Nordheim tunneling. Moreover，the memory capacitor also exhibits a capability of continuous electron trapping with prolonging of the programming duration.
Fabrication and magnetic properties of Co89Cu11 nanowire arrays with bunchy shape
Authors: Liu Xiao-Xu  , Wang Hong-Yan  , Liu Bao-Hai  , Zhu Wei  , Feng Lin  , Wu Guang-Heng  , Zhao Jian-Ling  , Li Yang-Xian  ,   (1)河北工业大学材料学院，天津 300130; (2)河北科技师范学院数理系，秦皇岛 066004; (3)中国科学院物理研究所北京凝聚态物理国家实验室，北京 100190
Published: December 2020

Co89Cu11 nanowire arrays with particular bunchy shape have been fabricated in anodic aluminum oxide templates by electrodeposition. The analysis of structure indicates that the bunchy shape of the nanowire actually is a very high concentration of stacking faults parallel to the wire. Then we give explanation to the structure according to the growth mechanism. Relatively high squareness parallel to the nanowire arrays of about 096 at room temperature were achieved owing to the larger shape anisotropy than the nanowire arrays with general structure. The results of magnetic measurement and calculation demonstrate that the symmetric fanning mechanism of sphere-chains model can be employed to explain the magnetization reversal process which rest with the structure of the Co89Cu11 nanowire arrays.
Investigation on the effect of cathode work function and exciton generation rate on the open-circuit voltage of single layer organic solar cell with Schottky contact
Authors: Li Rong-Hua  , Meng Wei-Min  , Peng Ying-Quan  , Ma Chao-Zhu  , Wang Run-Sheng  , Xie Hong-Wei  , Wang Ying  , Ye Zao-Chen  ,   (1)兰州大学磁学与磁性材料教育部重点实验室，兰州 730000; (2)兰州大学物理学院微电子研究所，兰州 730000; (3)兰州大学物理学院微电子研究所，兰州 730000；兰州大学磁学与磁性材料教育部重点实验室，兰州 730000
Published: December 2020

In this article，we investigate the effect of cathode work function，exciton generation rate and temperature as well as carriers and field distribution in the organic layer on the open-circuit voltage （Voc） of single layer organic solar cell with Schottky contact by using numerical method. It is demonstrated that the decrease of cathode work function （Wc） contribute to the increase of open-circuit voltage until Wc is close to the LOMO level of the organic material. The open-circuit voltage reaches a saturation value，when Wc is smaller then |EL|，and this open-circuit saturation voltage increases with the enhancement of exciton generation rate. For a given anode and cathode work function，the open-circuit voltage increases with exicton generation rate. When the exciton generation rate reaches a certain value，Voc goes to saturation instead of further increase，and the saturation value equals to the built-in voltage. Additionally，the saturated Voc decreases with the increase of temperature，and the decrease rate reduces with the increase of the exciton generation rate.
Dynamical characteristics of the fractional-order FitzHugh-Nagumo model neuron and its synchronization
Authors: Liu Yong  , Xie Yong  ,   西安交通大学航天航空学院强度与振动教育部重点实验室，西安  710049
Published: December 2020

Through the research on the fractional-order FitzHugh-Nagumo model neuron，it is found that the Hopf bifurcation point of the fractional-order model，where the state of the model neuron changes from quiescence to periodic spiking，is different from that of the corresponding integer-order model when the externally applied current is considered as the bifurcation parameter. We further demonstrate that the range of the strength of the externally applied current in the fractional-order model neuron，which can make the model neuron exhibit periodic spiking，is smaller than that in the corresponding integer-order model neuron. However，the firing frequency of the fractional-order model neuron is higher than that of the integer-order counterpart. Meanwhile，we show that the synchronization rate of two electrically coupled fractional-order FitzHugh-Nagumo model neurons is greater than that of the integer-order counterpart. The Adomian decomposition method is employed to calculate fractional-order differential equations numerically because of its rapid convergence and high accuracy.
Theoretical study of the influence of laser intensity on the population of the NO molecule electronic states
Authors: Ma Ning  , Wang Mei-Shan  , Yang Chuan-Lu  , Xiong De-Lin  , Li Xiao-Hu  , Ma Xiao-Guang  ,   鲁东大学物理与电子工程学院，烟台  264025
Published: December 2020

Using the time-dependent wavepacket method and employing the four-state model，the influence of the laser intensity on the population of the NO molecule electronic states are calculated in this paper. The populations of the electronic states of the NO are given by the wavefunctions obtained by solving the Schrdinger equation through the split-operator Fourier transform method. The calculated results show that different pump pulse intensities have different influences on the population of the electronic states of NO. By changing the pulse intensity，the ionization ratio can be controlled，which will benefit the light manipulation of atomic and molecular processes.
Effects analysis of rainfall on microwave transmission characteristics
Authors: Liu Xi-Chuan  , Gao Tai-Chang  , Qin Jian  , Liu Lei  ,   解放军理工大学气象学院，南京 211101
Published: December 2020

Based on the normalized raindrops size distribution，dielectric model of raindrop and Mie scattering theory，the scattering characteristic of raindrop cluster in the microwave and millimeter domain are calculated，the effect of raindrop size distribution，rain-rate，incidence wave frequency and temperature on the microwave transmission are discussed. The results show that the scattering capabilities of raindrop clusters decrease in the order of JD，MP，Gamma and JD. The effect of rain-rate on microwave transmission is the strongest，the incidence wave frequency takes second place，and the temperature is the weakest. These results will be helpful to the evaluation of the effect of precipitation on microwave transmission and the improvement of the precipitation detection precision of millimeter radar and precipitation-measuring radar，etc.
Device fabrication of semi-insulating surface-plasmon terahertz quantum-cascade lasers
Authors: Li Hua  , Han Ying-Jun  , Tan Zhi-Yong  , Zhang Rong  , Cao Jun-Cheng  ,   信息功能材料国家重点实验室，中国科学院上海微系统与信息技术研究所，上海  200050
Published: December 2020

The active region of GaAs/AlGaAs bound-to-continuum terahertz quantum-cascade laser （THz QCL） is grown by gas-source molecular beam epitaxy. The device fabrication process of semi-insulating surface-plasmon THz QCL is studied in detail. The electrical and optical characteristics of the fabricated THz QCL device are measured using a far-infrared Fourier transform infrared spectrometer with a deuterated triglycerine sulfate far-infrared detector. At 10 K，the measured lasing frequency is 32 THz and the threshold current density is 275 A/cm2.
Available material for prolonging the decoherence time of Rb atom
Authors: Luo Xiao-Ming  , Chen Li-Qing  , Ning Bo  , Jiang Shuo  , Zhong Zhi-Ping  ,   (1)清华大学物理系，北京 100084; (2)中国科学院研究生院物理学院，北京 100049
Published: December 2020

We have measured the Rb atomic spin lifetime in both of paraffin-coated cell and glass cell. The experimental results shows that the lifetime of Rb atomic spin in paraffin-coated cell is about 7 ms at temperature T=50 ℃, while the data in glass cell is about 20 μs, which is useful for quantum memory experiments based on atomic spin. Meanwhile, we discuss other potential materials which can be used to eliminate the inelastic collisions between alkali metal atoms and walls. Based on some experimental data and investigation, we think that BN and C60H60 may be the candidates.