bluuebunny/crossref_metadata_2025 huggingface dataset:
Generalized projective synchronization of chaotic system based on a single driving variable and its application in secure communication
Authors: Li Nong  , Li Jian-Fen  ,   (1)空军工程大学工程学院，西安  710038; (2)空军工程大学理学院，西安  710051
Published: December 2020

A generalized projective synchronization method is proposed based on unidirectional coupled synchronization by only transmitting a single driving variable. The proposed method allows us to arbitrarily direct the scaling factor to a desired value. Since chaos synchronization can be achieved by transmitting a single variable from driving system to response system, this method is more practical. Theoretical deduction and computer simulation show the effectiveness of the proposed method. A scheme for secure communication, which can increase the security of a communication system, is presented based on generalized projective synchronization of unified chaotic system.
Study of attractor based on tangent-delay for elliptic reflecting cavity
Authors: Tan Si-Ting  , He Yi  , Sheng Li-Yuan  ,   中南大学物理科学与技术学院，长沙  410083
Published: December 2020

By introducing the conversion function on ellipse angle, we use the method of shift matrix to achieve the simplification of ellipse problem. A very simple iterative formula is deduced on the tangent-delay for elliptic reflection, which is very useful for theoretical analysis. There exits a chaotic attractor when tangent delays one unit in TD-ERCS. The origin of the attractor and its stability are analyzed in theory. We find that the attractors in the circular and the elliptic cases are not entirely the same; the ellipse has two immobile lines, but only one of them is steady. We also find that, with the decrease of ellipse compression factor μ, the correlation of nearby iterative data is strengthened when the tangent-delay factor m is arbitrary. It means that in using the system for cryptography, the ellipse compression factor μ can not be too small, and the chaos system requires that it should not be too big, otherwise the degree of safety will be reduced.
Anti-control of Hopf bifurcation at zero equilibrium of 4D Qi system
Authors: Liu Su-Hua  , Tang Jia-Shi  ,   (1)湖南大学力学与航空航天学院,长沙  410082; (2)上海工程技术大学高职学院，上海  200437；湖南大学力学与航空航天学院,长沙  410082
Published: December 2020

Anti-control of Hopf bifurcation at the zero equilibrium of the 4D Qi system is achieved by the linear and nonlinear state feedback. First, aimed at the emergence of the Hopf bifurcation, linear control terms are determined and the conditions which the linear control gains should satisfy are presented. Then, with respect to the nonlinear control terms, which are associated with the stability of Hopf bifurcation, the nonlinear feedback applied directly to the Jordan form of the Qi system is investigated. By the stability analysis and a proper transformation, the nonlinear control terms which play roles on the stability of Hopf bifurcation are collected and the condition restricting the nonlinear control gain isobtained. The control strategy is different as the bifurcation parameter concerned is altered. Finally, the numerical results are presented that confirm the analytical predictions.
Response analysis of two-degree-of-freedom impact oscillator to random excitation
Authors: Wang Liang  , Xu Wei  , Li Ying  ,   西北工业大学理学院应用数学系，西安  710072
Published: December 2020

The response of a two-degree-of-freedom impact oscillator to random excitation is investigated. The existence of grazing bifurcation involved in the period-doubling bifurcation is shown clearly. The effects of the random excitation are studied by defining a measure of the stochastic response. The idea that the random factor can change the property of the system in some conditions is proposed. Numerical simulations show that the method is effective.
Low-frequency oscillation in digitally controlled DC-DC Buck converters
Authors: Zhang Xiao-Tian  , Ma Xi-Kui  , Zhang Hao  ,   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

The z-domain model of digitally controlled Buck converter is derived by only considering the effect of sampler-and-holder. Based on the z-domain model, the cause of the low-frequency bifurcation is analyzed. The location and type of the bifurcation point when a system loses stability is predicted in terms of the system eigenvalues. Moreover, the frequency and the amplitude of the low-frequency oscillation, i.e., the wave equations, are deduced. These theoretical results are verified by PSpice simulations.
Two codimension-3 bifurcations and non-typical routes to chaos of a shaker system
Authors: Zhang Yong-Xiang  , Kong Gui-Qin  , Yu Jian-Ning  ,   (1)兰州交通大学数理与软件工程学院，兰州  730070; (2)沈阳农业大学理学院，沈阳  110161; (3)中国船舶工业第六三五四研究所，九江  332000
Published: December 2020

The dynamical model and Poincaré maps of a shaker are established. Two types of codimension-3 bifurcations of this system, including Flip-Hopf-Hopf bifurcation and Hopf-Hopf bifurcation in the third order strong resonant case, and three non-typical routes to chaos are investigated by using Poincaré maps. The system exhibits more complicated dynamic behaviors near the points of codimension-3 bifurcation. The results show that near the points of bifurcation there existtriangle attractor, 3T2 torus bifurcation and “pentalpha-like”, “tire-like” attractors in projected Poincaré sections. The routes to chaos via torus explosion, torus-doubling bifurcation and T2 torus bifurcation are analyzed by numerical simulation. The system parameters of shaker may be optimized by studying the stability and bifurcation of periodic motion of the shaker.
Encryption based on inverse iterating composition cellular automata system
Authors: Ping Ping  , Zhao Xue-Long  , Zhang Hong  , Liu Feng-Yu  ,   南京理工大学计算机科学与技术学院，南京  210094
Published: December 2020

The concepts of cross composition cellular automata and random composition cellular automata are introduced, and their feasibility in application to cryptosystem is analyzed. We use the inverse iteration of cellular automata to encrypt, and construct two encryption systems based on composition cellular automata. The new encryption systems effectively solve the problem of one way error diffusion in a single cellular automata system and acquire large key space with small rule radius. Simulation experiment shows that the diffusion and confusion properties of the new composition system are ideal, it resists brute attack and differential cryptanalysis.
Resonance characteristics of a three-dimensional anisotropic metamaterial bilayer
Authors: Meng Fan-Yi  , Wu Qun  , Fu Jia-Hui  , Gu Xue-Mai  , Li Le-Wei  ,   哈尔滨工业大学电子与信息技术研究院，哈尔滨  150001
Published: December 2020

The resonance characteristics of a three-dimensional anisotropic metamaterial bilayer is investigated through solving the resonance equation for a rectangular cavity filled with two layers of different isotropic metamaterials. It is found that the solution of subwavelength resonance is highly dependent on the product of the transversal and longitudinal permeabilities，and there exist more than one for the subwavelength resonance in most cases. In addition，it is found that the width of the corresponding waveguide of the rectangular cavity has an essential effect on the number of solutions for the resonance condition equation. These results are of significance in the application of the metamaterials to sub-wavelength resonance structures and miniaturized cavity resonators.
Fully relativistic distorted-wave calculations for electron impact excitation of highly chargednickel-like ions
Authors: Xie Lu-You  , Zhang Zhi-Yuan  , Dong Chen-Zhong  , Jiang Jun  ,   (1)西北师范大学物理与电子工程学院，兰州  730070; (2)西北师范大学物理与电子工程学院，兰州  730070；兰州重离子加速器国家实验室原子核理论研究中心，兰州  730000
Published: December 2020

A fully relativistic distorted-wave method and the corresponding procedure REIE06 have been developed recently to study the electron impact excitation processes of highly charged ions. In this study，we calculated the collision strengths，cross sections and rate coefficients for electron impact excitation of highly charged Nickel-like Gd36+，Rn58+—U64+(Z=86—92)ions from the ground state to 106 low-lying excitated states. In the calculations，the relativistic effects，electron correlation effects，Breit interactions and high partial wave contributions are considered systematically. Based on the calculations，we studied the contribution of Breit interaction to collision strengths，the cross sections connected with the strongest 4d-4p (J=0—1) X-ray laser transitions along the Ni-like sequence，and the effects of strong configuration interaction on cross sections from the ground state 3d101S0 to the (3d3/24d5/2)1，(3d3/24d3/2)1 and (3p3/24p1/2)1 states. A comparison was made between the present results and previous theoretical calculations for collision strengths of Gd36+ and U64+ ions，and rate coefficients of Gd36+ ion，good agreement was obtained.
Design of a hybrid infrared apochromatic optical system beyond normal temperature
Authors: Song Yan-Feng  , Shao Xiao-Peng  , Xu Jun  ,   西安电子科技大学技术物理学院，西安  710071
Published: December 2020

The principle and design method of employing diffractive optical element to athermalize an infrared optical system are discussed. An analysis is made on the diffractive optical elements dispersion characteristics and its superiority in correcting the second spectrum. A hybrid infrared optical system，as a practical application example，which has realized apochromatism and works beyond normal temperature, is presented. The parameters of the system are as follows: the focal length is 100mm，relative aperture is 1/2，field of view is 6°，and the working waveband is 8—11μm. In the system，only two materials，namely silicon and germanium, are used. The image quality of the system achieves the diffractive limit within the temperature range of -80—200℃. At about 0.7 aperture，three longitudinal aberration curves of the system intersect at one point，and the apochromatism of the optical system is achieved.
Study on the critical free electron density for nanosecond laser pulse focusing in air
Authors: Han Jing-Hua  , Feng Guo-Ying  , Yang Li-Ming  , Zhang Qiu-Hui  , Jia Jun  , Li Gang  , Zhu Qi-Hua  , Zhou Shou-Huan  ,   (1)四川大学电子信息学院，成都  610064; (2)四川大学电子信息学院，成都  610064；中国工程物理研究院激光聚变研究中心，绵阳  621900; (3)中国工程物理研究院激光聚变研究中心，绵阳  621900
Published: December 2020

Experimental study on the energy transmissivity of high -power nanosecond laser pulse focusing in air versus input laser energy has been carried out. There are three stages: when the input laser energy is relatively low，all of the laser energy can pass through the focusing point; when the input laser energy increases gradually，energy transmissivity decreases steeply from nearly 100% to lower values; when the input laser energy keeps on increasing，the transmissivity decreases slowly further. By defining the critical electron density and the corresponding critical time point，successful theoretical analysis has been carried out for the above experimental phenomena. When the free-electron density is less than the critical value，multiphoton ionization plays the dominating role; when the free-electron density is higher than the critical value, the inverse bremsstrahlung process dominates. The critical time point is the time when laser pulse reaches critical electron density in the process of laser pulse passing through the air; its position on the laser pulse is determined by the input laser pulse energy，meanwhile this position determines the energy transmissivity of the laser pulse. So we can calculate the critical electron density by measuring the transmissivity versus input energy and comprehend the characteristics of transmissivity for laser pulse focusing in the air.
Experimental study of characteristics of high power photonic crystal fiber amplifier
Authors: Zhao Zhen-Yu  , Duan Kai-Liang  , Wang Jian-Ming  , Zhao Wei  , Wang Yi-Shan  ,   (1)中国科学院西安光学精密机械研究所瞬态光学技术国家重点实验室，西安  710119; (2)中国科学院西安光学精密机械研究所瞬态光学技术国家重点实验室，西安  710119；中国科学院研究生院，北京  100049
Published: December 2020

The gain characterization of photonic crystal fiber amplifier is theoretically and experimentally studied by using reverse pumping technique. The gain curves for different pumping powers and different signal lights are obtained experimentally. When the power of the probe light is 6W and the pump power is 160W，the output power up to 104W，has been achieved eventually. It is found in the experiment that when the pump power is increased over a certain value，the output of the amplifier evolves into the unstable state，which in turn degrades the system performance.
Large self-deflection of bright and dark screening photovoltaic solitons in LiNbO3
Authors: Zhang Yi-Qi  , Lu Ke-Qing  , Zhang Lei  , Zhang Mei-Zhi  , Li Ke-Hao  ,   (1)中国科学院西安光学精密机械研究所瞬态光学与光子技术国家重点实验室，西安  710119; (2)中国科学院西安光学精密机械研究所瞬态光学与光子技术国家重点实验室，西安  710119；中国科学院研究生院，北京  100049
Published: December 2020

We demonstrate large self-deflection of both bright and dark screening photovoltaic solitons existing in LiNbO3 crystal under an external applied field with numerical method, and we also demonstrate that the self-deflection is not only connected with the acceptor concentration NA but also with the external applied field E0. Under the same E0, when NA is lower, the self-deflection is more obvious. Under the same NA, when E0 is higher, the self-deflection is more obvious. We also find that self-deflection of the bright screening spatial soliton and that of the dark one are different: the bright screening photovoltaic soliton deflects obviously; while only one side of the dark soliton deflects, its extreme value point and the other side almost do not deflect.
New SBS media——perfluorinated amines
Authors: Hasi Wu-Li-Ji  , Lü Zhi-Wei  , Gong Sheng  , He Wei-Ming  , Lin Dian-Yang  , Zhang Wei  ,   (1)哈尔滨工业大学光电子技术研究所，哈尔滨  150001; (2)哈尔滨工业大学空间光学工程研究中心，哈尔滨  150001; (3)哈尔滨工业大学空间光学工程研究中心，哈尔滨  150001；哈尔滨工业大学光电子技术研究所，哈尔滨  150001
Published: December 2020

The stimulated Brillouin scattering (SBS) media perfluorinated amines with good SBS characteristics have been discovered based on the dependence of SBS characteristics on the chemical structures. The SBS parameters of perfluorinated amines such as FC-131, FC-3283, FC-40, FC-43 and FC-70 have been measured or calculated. The results demonstrate that their absorption coefficients are below 10-3cm-1 and optical breakdown thresholds are above 100GW/cm2. The perfluorinated amines also exhibit a series of unique physicochemical properties, i.e., non-toxic property, low volatility, and high stability. The discovery not only diversifies the SBS media, but also improves the performance of SBS system, thereby laying a good foundation for the application of SBS phase conjugation mirror in high-power laser systems.
Interaction between spacial optical solitons in sub-strongly non-local nonlinear media
Authors: Cao Long-Gui  , Lu Da-Quan  , Hu Wei  , Yang Ping-Bao  , Zhu Ye-Qing  , 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 investigate the interaction between spacial optical solitons in the sub-strongly non-local nonlinear media. From the light-rays equation, we obtained the evolution rule of the beam centers and found that the ratio of initial separation d0 between solitons and the characteristic length wm of the nonlocal nonlinearity have decisive influence on the interaction. We also found the largest angle below which the solitons can be attracted at oblique incidence. Numerical simulations confirm our theoretical results.
The design, fabrication and performance of a large area 10000 line/mm metal transmission diffraction gratings for soft X-ray
Authors: Zhu Wei-Zhong  , Wu Yan-Qing  , Guo Zhi  , Zhu Xiao-Li  , Ma Jie  , Xie Chang-Qing  , Shi Pei-Xiong  , Zhou Hong-Jun  , Huo Tong-Lin  , Tai Ren-Zhong  , Xu Hong-Jie  ,   (1)丹麦科技大学,哥本哈根  2800; (2)中国科技大学国家同步辐射实验室,合肥  230029; (3)中国科学院微电子研究所,北京  100029; (4)中科院上海应用物理研究所，上海   201800
Published: December 2020

Based on the rigorous coupled-wave analysis, the optimized design for a transmission two-gratings mask for 13.4nm soft X-ray interference lithography has been accomplished. Then a large area transmission gratings was successfully fabricated by electron beam lithography (EBL), which has an area of 1.5mm×1.5mm, ruling period of 100nm, Cr relief thickness of 50nm, gap/period of 0.6, and Si3N4 substrate thickness of 100nm. Based on the quantitative estimation of the measurement data, the first and second order diffraction efficiencies were determined as 4.41% and 0.49%, respectively， in good agreement with the numerical simulation results. Through comparison between the measurement and the numerical simulation results, it was shown that the relief is entirely vertical and the gap/period was well controlled. This two-grating mask will be used installed on the soft X-ray interference lithography endstation at Shanghai Synchrotron Radiation Facility (SSRF). With its 1st and 2nd order diffraction, 50nm period and 25nm period gratings can be cost-effectively fabricated, respectively.
Phase-modified coupled mode theory for calculation of fiber Bragg grating Fabry-Perot cavity transmission spectrum
Authors: Wang Yan-Hua  , Ren Wen-Hua  , Liu Yan  , Tan Zhong-Wei  , Jian Shui-Sheng  ,   北京交通大学光波技术研究所，全光网络与现代通信网教育部重点实验室，北京  100044
Published: December 2020

Based on the influence of reflection phase of fibre Bragg grating on the transmission spectrum of fibre Bragg grating(FBG) Fabry-Perot cavity, the reason for the error of traditional coupled mode theory when calculating the reflection phase of uniform FBG is analyzed. A parameter of initial phase of effective index distribution is introduced to describe the slight offset of the index distribution of FBG in the longitudinal direction, and the real reflection and transmission coefficients are substituted for the simplified coefficients to modify the traditional coupled mode theory by introducing a phase factor, which is related with the initial phase of effective index distribution and independent of wavelength. The phase of transfer matrix method for nonuniform FBG is further modified. The modified fast calculation results are used to calculate the transmission spectrum of FBG F-P cavity and show the influence of initial phase of effective index distribution on the wavelength offset of FBG Fabry-Perot cavity transmission peaks. The results agree with those of Rouard method and experimental values.
Phase locking of three fiber lasers using an all-fiber coupling loop
Authors: Lei Bing  , Feng Ying  , Liu Ze-Jin  ,   国防科技大学光电科学与工程学院,长沙  410073
Published: December 2020

An all-fiber coupling loop is constructed by three 2×2 fiber couplers according to certain rules, which connects three independent erbium-doped fiber lasers to form a coupled array. Thanks to the specially designed all-fiber coupling loop, the total loss of the phase locking array is reduced remarkably, and effective mutual injection coupling occurs between the component fiber lasers, so that the phase locking of the array is achieved. The far field interference patterns and output spectrum observed in experiment indicate that the array has achieved phase locking states. When the pump power of three component fiber lasers is 100mW each, the phase locking array gives 94mW stable coherent output.
Characteristics of electron energy distribution function of capacitively coupled plasma excited by 60MHz RF source
Authors: Sun Kai  , Xin Yu  , Huang Xiao-Jiang  , Yuan Qiang-Hua  , Ning Zhao-Yuan  ,   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

Capacitively coupled plasma (CCP) source excited by very-high-frequency (VHF) source has attracted much attention in semiconductor industry due to its ability to generate high density plasma with a large area. The electron behavior and discharge properties of capacitively coupled plasma excited by 60MHz RF source were investigated by using current and voltage probe and Langmuir probe techniques. The experimental results show that equivalent resistance or capacitance of capacitively coupled plasma decreases or increases, respectively, with the increment of input RF power. It is also shown that the electron behavior in the plasma is related not only with RF input power but also discharge pressure. Increase in pressure causes the transition of electron energy distribution function from Bi-Maxwellian type to Druyvesteyn type, with its transition pressure much lower than that reported by others, which is due to a great decrease in efficiency of electron bounced resonance heating in CCP driven by 60MHz.
Structure and physical properties of La0.1Bi0.9-xEuxFeO3 compounds
Authors: Liu Yan-Hui  , Li Jing-Bo  , Liang Jing-Kui  , Luo Jun  , Ji Li-Na  , Zhang Ji-Ye  , Rao Guang-Hui  ,   (1)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; (2)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；中国科学院国际材料物理中心，沈阳  110016
Published: December 2020

In this work, La0.1Bi0.9-xEuxFeO3 compounds were prepared by solid-state reaction. The phase relation at room temperature was investigated by X-ray powder diffraction. A rhombohedral (R3c) phase exists for x≤0.05; for 0.08≤x≤0.12 a pseudo-R3c phase is found; for x≥0.15 it is an orthorhombic (Pbnm) phase, while the distortion of the Pbnm phase was observed for the composition range of 0.15≤x≤0.20. Magnetic measurements indicate that weak ferromagnetism exists in all the compounds, and for the compounds with x≤0.20 the magnetic moment has the maximum value at x=0.12. The composition dependence of dielectric constant was investigated at room temperature. The relationship between the structure and the physical properties was discussed.
Structure and thermoelectric properties of n-type GaxCo4Sb12 skutterudite compounds
Authors: Su Xian-Li  , Tang Xin-Feng  , Li Han  , Deng Shu-Kang  ,   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

Ga-filled GaxCo4Sb12 skutterudite compounds with different Ga contents were synthesized by combining a melting quenching-diffusion-annealing procedure with spark plasma sintering (SPS). The effects of Ga content on thermoelectric properties were investigated. The results of Rietveld refinement indicated that the Ga is located in the 2a void site. The solubility limit of the Ga filling voids in CoSb3 was found to be close to 0.22. The electrical conductivity and the room temperature carrier concentration Np of the samples increase with the increasing Ga content for Ga filled GaxCo4Sb12 skutterudite compounds with x≤0.25, while the Seebeck coefficient decreases with the increasing Ga content. Room temperature Hall measurements show that each Ga atom donates approximately 0.9 electrons, which is significantly less than that of the Ga oxidation state (3+). Ga-filled skutterudites exhibit much lower thermal conductivity and lattice thermal conductivity in comparison with that of other partially filled skutterudites due to the smaller radius of Ga3+ ions compared with that of other filling atoms. The thermal conductivity and lattice thermal conductivity of Ga0.22Co4Sb12 compound are 3.05Wm-1·K-1 and 2.86Wm-1·K-1 respectively. The Ga0.22Co4Sb12 compound possesses the lowest lattice thermal conductivity at 600K. It is as low as 1.83Wm-1·K-1. The maximum Z value of 1.31×10-3K-1 is obtained at 560K for Ga0.22Co4Sb12.
Interfacial friction calculation based on the coupled-oscillator model
Authors: Ding Ling-Yun  , Gong Zhong-Liang  , Huang Ping  ,   华南理工大学机械与汽车工程学院,广州  510640
Published: December 2020

A new model named the coupled-oscillator model, in which the relationship of the lateral force and the normal force are considered, is proposed for studying the interfacial friction. The Maugis-Dugdal model is used to approximately substitute the Lennard-Jones potential of the interfacial friction in the new model. Then, the formulas for frictional force calculation are deduced. Comparison between the theoretical results and the experimental data obtained by an atomic force microscope shows that the model and the formulas are practically feasible. Based on the coupled-oscillator model, it is found that the frictional force increases approximately with the 2/3th power of the normal force for a tip-sample contact system, which is the same as the classical conclusion of nano-tribology.
Electronic structure and optical properties of GaN with Mn-doping
Authors: Xing Hai-Ying  , Fan Guang-Han  , Zhao De-Gang  , He Miao  , Zhang Yong  , Zhou Tian-Ming  ,   (1)华南师范大学光电子材料与技术研究所，广州  510631; (2)中国科学院半导体研究所集成光电子学国家重点联合实验室，北京  100083
Published: December 2020

Calculations of the electronic structure and the density of states of GaN with Mn are carried out by means of first-principles plane-wave pesudopotential method based on density functional theory. The results reveal a 100% spin polarized impurity band in band structure of Ga1-xMnxN due to hybridization of Mn 3d and N 2p orbitals. The material is half metallic and suited for spin injectors. In addition, a peak of refractive index can be observed near the energy gap. The absorption coefficient increases in the UV region with the increase of the Mn content.
Theoretical study on the relative stability of α-Ga and β-Ga nanowires in carbon nanotubes
Authors: Xu Bo  , Pan Bi-Cai  ,   (1)合肥微尺度物质国家实验室(筹)，合肥  230026；中国科学技术大学物理系，合肥  230026; (2)江西师范大学物理与通信电子学院，南昌  330027
Published: December 2020

The stabilities of the gallium nanowires filled in carbon nanotubes (CNTs) have been studied using density functional theory (DFT). The results show that whether in CNTs or in free space, β-Ga nanowires with large sizes are more stable than α-Ga ones. By analyzing the average energies of gallium nanowires as well as the binding energies between gallium nanowires and CNTs, the reasons why not α-Ga but β-Ga is experimentally observed in CNTs are revealed.
Multiscale entropy complexity analysis of metallic interconnection electromigration noise
Authors: He Liang  , Du Lei  , Zhuang Yi-Qi  , Li Wei-Hua  , Chen Jian-Ping  ,   (1)西安电子科技大学技术物理学院，西安  710071; (2)西安电子科技大学微电子学院，西安  710071
Published: December 2020

In order to solve the limitation of traditional frequency-domain analysis in Al interconnection electromigration noise, the multiscale entropy (MSE) method is proposed to analyze the electromigration noise time series. The result shows that at the early stage, electromigration noise is irregular, the noise complexity is large, and with the occurrence of nucleation, the electromigration noise becomes more regular, and the complexity decreases obviously. It indicates that the disorder degree of electromigration system decreases continually. Compared with traditional parameters, MSE can be used to successfully characterize electromigration process.
A new partial SOI high voltage device with double-faced step buried oxide structure
Authors: Li Qi  , Zhang Bo  , Li Zhao-Ji  ,   (1)电子科技大学IC设计中心，成都  610054; (2)桂林电子科技大学信息与通信学院，桂林  541004；电子科技大学IC设计中心，成都  610054
Published: December 2020

A novel PSOI (partial silicon_on_insulator) high voltage device with double-faced step buried oxide is proposed, which is called DSB PSOI(PSOI with double_faced step buried_oxide layer). The surface electric field has ideally uniform distribution due to the additive electric field modulation by double step buried oxide. A silicon window underneath the source helps to reduce self-heating.The depletion region spreads into the substrate and the vertical electric field in the buried layer is enhanced, which results in a higher breakdown voltage than that of conventional SOI device. A 2-D quantified optimal relation between the structure parameters is also obtained. The results indicate that the breakdown voltage of DSB PSOI is increased by 58% in comparison with conventional SOI, while maintaining the low on-resistance of the DSB PSOI device.
Electromagnetic and microwave properties of discontinuous CoFeB/MgO soft magnetic multilayer films
Authors: Ma Qiang  , Jiang Jian-Jun  , Bie Shao-Wei  , Du Gang  , Feng Ze-Kun  , He Hua-Hui  ,   华中科技大学电子科学与技术系，武汉  430074
Published: December 2020

A series of discontinuous multilayers of CoFeB-MgO was fabricated by using DC/RF magnetron sputtering, and the electromagnetic and microwave properties were investigated. The results show that the microstructure and electromagnetic properties of the CoFeB-MgO discontinuous multilayer films can be altered by varying the relative content of the magnetic CoFeB phase and the insulating MgO phase. High performance microwave soft magnetic properties along with high resistivity are achieved in the discontinuous ［Co64Fe24B12(0.7nm)/MgO(0.4nm)］40 multilayer film. This film has the saturation magnetization of 1.3 T, hard axis coercivity of 130 A/m, and resistivity of 3.4 mΩ·cm. Moreover, the resonance frequency is about 2.1 GHz for this film. Both the real part μ′ and the imaginary part μ″ of the measured permeability are larger than 240 at 1.59 GHz and are both larger than 100 from 0.9 GHz to 2 GHz. So this film has potential for serving as the microwave absorbers and electromagnetic compatibility materials in the GHz frequency range.
Magnetoelectric effect in transition-metal-doped BaTiO3-Tb1-xDyxFe2-y bilayer
Authors: Cao Hong-Xia  , Zhang Ning  ,   南京师范大学磁电子学实验室，南京  210097
Published: December 2020

1.0 mol% Mn(Cr,Co)-doped BaTiO3 have been synthesized with sol-gel technique. The doped BaTiO3 were found to have tetragonal structure at room temperature. The phase transition temperatures and the latent heat of ferroelectric to paraelectric transition were observed to decrease with Cr, Mn and Co doping in BaTiO3. Magnetic characterizations including magnetostriction and magnetization were performed for Tb1-xDyxFe2-y(TDF). Bonded bilayer composites Cr∶BTO-TDF, Mn∶BTO-TDF and Co:BTO-TDF have been fabricated and the transverse ME effect of the three bilayers have been investigated. The maximum transverse ME voltage coefficients for Cr∶BTO-TDF bilayer can reach 586mV·cm-1·(80　A·m-1)-1 under a bias magnetic field of 340×80 A·m-1, and that for Mn∶BTO-TDF and Co:BTO-TDF are 480 mV·cm-1·(80 A·m-1)-1 and 445 mV·cm-1·(80 A·m-1)-1 under a bias magnetic field of about 400×80　A·m-1, respectively.
Energy-dependent evolution of electron spin polarization in bulk intrinsic GaAs
Authors: Teng Li-Hua  , Yu Hua-Liang  , Zuo Fang-Yuan  , Wen Jin-Hui  , Lin Wei-Zhu  , Lai Tian-Shu  ,   中山大学光电材料与技术国家重点实验室，物理科学与工程学院，广州  510275
Published: December 2020

Time-resolved circularly polarized pump-probe spectroscopy is used to study the electron spin coherence dynamics in intrinsic GaAs at 9.6K. It is found that the oscillation amplitude of absorption quantum beats reflecting electron spin coherence varies nonmonotonically with photon energy increaing. A circularly dichromatic pump-probe model is developed with both spin-polarized-dependent band filling and band-gap renormalization effects taken into account. The model shows that the oscillation amplitude of quantum beats is dependent on the initial degree of electron spin polarization, spin-detectable sensitivity and band-filling factor whose product results in the non-monotonic variation of the quantum-beat amplitude and agrees very well with our experimental results. The degree of electron-spin polarization involved in energy-split two-level system is defined for the first time. It is found that a degree of electron spin polarization of up to 100% can be photocreated at higher excess-energy levels.
Magnetic field effect of charged excitons in n-doped ZnSe/BeTe type-Ⅱ quantum wells
Authors: Ji Zi-Wu  , Mino Hirofumi  , Oto Kenichi  , Muro Kiyofumi  , Akimoto Ryoichi  , Takeyama Shojiro  ,   (1)产业技术综合研究所超高速光学器件研究实验室，茨城  305-8568; (2)东京大学物性研究所,柏  277-8581; (3)千叶大学大学院理学部，千叶  263-8522; (4)山东大学物理学院，济南  250100；东京大学物性研究所,柏  277-8581
Published: December 2020

We report results of the reflection (type-I, in ZnSe layer) and photoluminescence (PL) spectra (type-Ⅱ) measurements performed on n-doped ZnSe/BeTe/ZnSe type-Ⅱ quantum well structures at low temperature (5—10 K). The reflection spectra show a typical charged exciton (X-) feature. The PL spectra show an asymmetry of the peak, which is a characteristic feature for a charged exciton type transition. The dependence of the PL peak energy on the in-plane magnetic field is considered to be due to the magnetic-field-induced displacement of interlayer negatively charged exciton dispersion in momentum space.
Exciton tunnelling in (CdZnTe,ZnSeTe)/ZnTe complex quantum wells
Authors: Jin Hua  , Liu Shu  , Zhang Zhen-Zhong  , Zhang Li-Gong  , Zheng Zhu-Hong  , Shen De-Zhen  ,   (1)中国科学院长春光学精密机械与物理研究所激发态物理重点实验室，长春  130033; (2)中国人民公安大学安全防范系，北京  102416
Published: December 2020

A new type of (CdZnTe,ZnSeTe)/ZnTe complex quantum wells was designed. Exciton tunneling process was investigated in this complex structure using absorption spectra, photoluminescence (PL) spectra and pump-probe measurements. The exciton decay time was measured in CdZnTe/ZnTe quantum well layers and ZnSeTe/ZnTe quantum well layers, respectively. And a fast exciton tunneling from CdZnTe/ZnTe quantum well to ZnSeTe/ZnTe quantum well was observed by transient differential trans mission. The tunneling time is 5.5ps.
Optical band gap of cubic boron nitride thin films deposited by sputtering
Authors: Deng Jin-Xiang  , Wang Xu-Yang  , Yao Qian  , Zhou Tao  , Zhang Xiao-Kang  ,   (1)北京工业大学应用数理学院，北京  100022; (2)兰州大学物理学院，兰州  730000
Published: December 2020

Cubic boron nitride thin films were deposited on silicon (100) substrates by sputtering. The films were characterized by Fourier transform infrared (FTIR) spectroscopy. The reflectance R(λ) of the films was obtained as a function of incident photon wavelengths and the thickness of the films was measured by Alpha-step. Using Kramers-Kronig transform and the reflectance spectrum R(λ), we calculated the absorption coefficient. The optical band gap was found to be 5.38eV for the films containing 55.4% of cubic phase.
Investigation on CNx films deposited by pulsed bias arc ion plating
Authors: Li Hong-Kai  , Lin Guo-Qiang  , Dong Chuang  ,   大连理工大学三束材料改性国家重点实验室，大连  116085
Published: December 2020

The CNx films with different nitrogen contents were prepared on single crystal Si(100) substrate under different nitrogen flow rates by pulsed bias arc ion plating. The surface morphology,composition,structure and properties of CNx films are investigated by optical microscope (OM),X-ray photoelectron spectroscopy(XPS), X-ray diffraction(XRD),Raman spectra and Nano-indentation, respectively. The results show that the surface of the films is uniform,smooth and dense. The nitrogen content in the CNx films decreases with the nitrogen flow rate decreasing. The results indicate that the deposited films are amorphous and have the typical characteristic of diamond-like carbon films. As the nitrogen content decreases from 18.9% to 5.3%, the hardness and elastic modulus of the films increase monotonically to a large extent, of which the hardness increases twice from 15.0 to 30.0 GPa. The sp3 content in the CNx films can be sensitively adjusted by controlling the nitrogen flow rate, leading to the changes of hardness and elastic modulus in large ranges.
Homotopic mapping method for solving a class of Lorenz system
Authors: Mo Jia-Qi  , Lin Wan-Tao  ,   (1)安徽师范大学数学系，芜湖  241000；上海高校计算科学院E-研究院上海交通大学研究所，上海  200240；湖州师范学院数学系，湖州  313000; (2)大气科学和地球流体力学数值模拟国家重点实验室，中国科学院大气物理研究所，北京  100029
Published: December 2020

The problem of solving the Lorenz equation is considered. Firstly，a set of homotopic mapping is constructed. Then the initial approximate solution is determined. Finally，using the homotopic mapping，the approximation for corresponding model is found. The homotopic mapping method is an analytic method，the obtained solution can be used in analytic operations subsequently.
Conformal invariance and Hojman conserved quantities of generalized Hamilton systems
Authors: Liu Chang  , Liu Shi-Xing  , Mei Feng-Xiang  , Guo Yong-Xin  ,   (1)北京理工大学理学院力学系，北京  100081; (2)辽宁大学物理学院，沈阳  110036; (3)辽宁大学物理学院，沈阳  110036；北京理工大学理学院力学系，北京  100081
Published: December 2020

In this paper the conformal invariance under infinitesimal transformations of generalized Hamilton systems is studied. The necessary and sufficient conditions for the conformal invariance under infinitesimal transformations which has Lie symmetry are given. Then we get the Hojman conserved quantities from conformal invariance of generalized Hamilton systems. Finally，an illustrative example is given to verify the result.
Mei symmetry and conserved quantity of a holonomic system
Authors: Ge Wei-Kuan  ,   湖州师范学院物理系，湖州  313000
Published: December 2020

The definition and the criterion of a Mei symmetry for a holonomic system are obtained in this paper.If the Mei symmetry is a Noether symmetry，the Noether conserved quantity is given，If the Mei symmetry is a Lie symmetry，the conserved quantity of Hojman type is obtained.An example is given to illustrate the application of the result.
Analytical approximations to the arbitrary l-wave bound state solutions of the Klein-Gordon equation for the Manning-Rosen potential
Authors: Wei Gao-Feng  , Long Chao-Yun  , Qin Shui-Jie  , Zhang Xin  ,   (1)贵州大学物理系，贵州  550025；贵州省光电子技术及应用重点实验室，贵州大学，贵阳  550025; (2)贵州省光电子技术及应用重点实验室，贵州大学，贵阳  550025; (3)西安文理学院物理系，西安  710065；贵州大学物理系，贵州  550025
Published: December 2020

The Klein-Gordon equation of equal scalar and vector Manning-Rosen potentials with the centrifugal term is investigated in the spherical coordinates. Using a proper exponential approximate approach，the radial Klein-Gordon equation with the centrifugal term is transformed to the hypergeometric differential equation，and the analytical bound state radial wave functions of the arbitrary l-wave Klein-Gordon equation are obtained. Finally，two special cases for l=0 and α=0 or 1 are discussed briefly.
Dynamical evolution for time-dependent qscillators
Authors: Wang Xiao-Qin  , Zhou Li-You  , Lu Huai-Xin  ,   潍坊学院物理与电子科学系，潍坊  261061
Published: December 2020

Based on the matrix of the time-dependent quantum transformation theory，we derive the analytic expression of the evolution operator for the time-dependent oscillators by using the time-dependent quantum transformation theory. Then the exact solution of the time-dependent oscillators is obtained.
Estimation and improvement of disaster spreading models based on complex network
Authors: Ouyang Min  , Fei Qi  , Yu Ming-Hui  ,   华中科技大学系统工程研究所，武汉  430074
Published: December 2020

Disasters threaten mankind and degrade our survival conditions，and have a serious impact on human society. Several previous disaster spreading models in complex networks are reviewed. Based on the evaluation of their advantages and disadvantages，a more realistic model in the networks with redundant systems is proposed. For different models in different network structures，the differences of spreading processes and the effects of some important parameters are analyzed by means of simulation. The disaster processes in the networks with redundant system become slow，which permits of longer rescue time to repair the system. It can explain the reason why large-scale disaster events rarely happen in real life.
The topologieal railway network of China constrained by the geographic factors
Authors: Tan Jiang-Xia  , Wang Du-Juan  , Wang Xin  , Wang Ru  , Cai Xu  ,   (1)湖北教育学院，物理与电子工程系，武汉  430060; (2)华中师范大学，物理科学与技术学院，武汉  430079
Published: December 2020

We made a detailed，empirical analysis of the railway network of China (RNC)，in which the stations are treated as nodes and a link exists between every two nodes if there is a train stop at each node. Firstly，we explore the statistical properties of the directed and weighted RNC with respect to the distribution of degree and strength，clustering coefficient and the shorted path length. The results exhibit that the distribution of degree and strength are between the exponential distribution and scale-free. Moreover，the RNC is a hierarchical small-world network. Secondly，the construction of the railway is the result of balance between the economical cost and the degree of need such as the population density and the number of administrative divisions. So the topological properties constrained by the geographic factors are taken into consideration，such as the relation between railroad length and degree，the density distribution of the stations and the population and the community strength of the province. These results proved that the RNC is constrained by the geography and approaches to the optimal construction.
Study of epidemic spreading on scale-free networks with finite maximum dissemination
Authors: Pei Wei-Dong  , Liu Zhong-Xin  , Chen Zeng-Qiang  , Yuan Zhu-Zhi  ,   (1)南开大学自动化系，天津  300071; (2)南开大学自动化系，天津  300071；天津师范大学计算机与信息工程学院，天津300387
Published: December 2020

Under the condition of infinite dissemination of the network，it has been proved that the classical epidemic models do not give epidemic thresholds in the infinite scale-free networks. That is，a disease can always propagate on the network no matter how low its spread speed. However，the ability of individuals to spread virus in many real networks is not always infinite. If the maximum dissemination of individuals in the network is set finite，then there should exist a non-zero epidemic threshold for the above epidemic models. The relations between the epidemic threshold and the maximum dissemination，the relations between the degree of infection and the maximum dissemination are discussed，meanwhile the reason why classical epidemic models always over-predict the degree of infections in real networks is explained.
Dynamical properties of ring dark soliton in quasi-two dimensional Bose-Einstein condensates
Authors: Zhang Wei-Xi  , Wang Deng-Long  , Ding Jian-Wen  ,   湘潭大学物理系和低维材料及其应用技术教育部重点实验室，湘潭  411105
Published: December 2020

By developing the multiple-scale method，we study analytically the dynamical properties of soliton in a quasi-two-dimensional Bose-Einstein condensate. For the repulsive inter-atomic interaction，a unstable dark soliton can be found in the condensate，which would evolve into ring dark soliton with small amplitude. Especially，it is shown that the ring dark soliton has dynamic stability.
Designing synchronization schemes for a fractional-order hyperchaotic system
Authors: Zhang Ruo-Xun  , Yang Shi-Ping  ,   (1)河北师范大学物理科学与信息工程学院,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；邢台学院初等教育学院,邢台  054001
Published: December 2020

Synchronization in a chaotic fractional-order differential system is studied. Three schemes are designed to achieve chaos synchronization of the fractional-order hyperchaotic system. Sufficient conditions on synchronization are also derived based on the Laplace transformation theory and stability theory of fractional-order linear systems. Numerical simulation or circuit simulation results are presented to demonstrate the effectiveness and feasibility of the proposed method.
Synchronization of fractional-order chaotic systems with different structures
Authors: Zhang Ruo-Xun  , Yang Shi-Ping  ,   (1)河北师范大学物理科学与信息工程学院,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；邢台学院初等教育学院,邢台  054001
Published: December 2020

Based on stability theory of fractional-order linear systems, a novel method combining feedback control and active control is proposed for the synchronization between two different fractional-order chaotic systems. The controller is obtained, and the method can be applied to solve synchronization problems of several classes of fractional-order chaotic systems, e.g., Lorenz system, Rssler system, Chen system, Liu system, Lü system, Rssler hyperchaotic system and the new hyperchaotic system. Numerical simulation results are presented to demonstrate the effectiveness and feasibility of the proposed method.
Simulation of bi-directional pedestrian flow based on cellular automata model
Authors: Yue Hao  , Shao Chun-Fu  , Chen Xiao-Ming  , Hao He-Rui  ,   北京交通大学交通运输学院,北京  100044
Published: December 2020

Simulations of bi-directional pedestrian flow with different direction splits and system sizes are presented based on cellular automata (CA) in this paper. It is well known that pedestrian movement is more flexible and adaptive to the dynamic conditions than vehicular flow, so four dynamic parameters are formulated to simplify tactically the decision-making process of pedestrians, which can reflect the pedestrian's judgment on the surrounding conditions and decide his her choice of action. The relationships of velocity-density and volume-density at different direction splits and on the different size system are studied and analyzed. It is found that there are phase transitions and a critical density point in the model and the relationships of velocity-density and volume-density are different in different phases. And the ratio of direction splits and system size affect the shapes of velocity-density curve, volume-density curve and the value of critical density point.
Vectorial Hopkins formulation depending on angles of off-axis illumination
Authors: Cao Peng-Fei  , Cheng Lin  , Zhang Xiao-Ping  ,   兰州大学信息科学与工程学院，兰州  730000
Published: December 2020

Basing on vector electromagnetic theory and the waveguide model, the vectorial Hopkins formula is deduced. It containes incidence angle and azimuth angle of off-axis illumination, which is different from the traditional scalar Hopkins formula. By simulating the aerial image of the three dimensional mask in actual lithography process, the optimal angular range of oblique incidence is analyzed, and the impact of oblique incidence angle on imaging quality is also discussed.
Doubled random-phase encryption based on discrete quaternion fourier-transforms
Authors: Gai Qi  , Wang Ming-Wei  , Li Zhi-Lei  , Zhai Hong-Chen  ,   南开大学现代光学研究所，天津  300071
Published: December 2020

In this paper, a new method for color-image encryption using discrete quaternion fourier-transforms (DQFT) combined with doubled random-phase encryption as used in the optical implementation is proposed, by which color images can be processed as a whole, rather than as separated color components in three channels, so that the complexity of the encryption system can be effectively reduced without any reduction in its security. The principle of both encryption and decryption is detailed and the robustness of the system has been examined experimentally.
A method for measuring thermal focal length of LD-side-pumped laser crystal
Authors: Geng Ai-Cong  , Zhao Ci  , Bo Yong  , Lu Yuan-Fu  , Xu Zu-Yan  ,   (1)北京工商大学数理系，北京  100037; (2)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

This paper reports a simple and accurate method for measuring thermal focal length of LD-side-pumped laser crystal. While applying the nonsymmetrical plane-plane-cavity to measure the thermal focal length, the distance from the end of the laser crystal to the end mirror need not be zero, and the reliability of this method is proved by experiments. Based on the obtained measurement results, folding configuration oscillators of yellow laser for intracavity sum frequency can be optimized, which ensures high space overlapping of two fundamental beams and high sum frequency efficiency.
Study of mathematical model for auto-alignment in four-pass amplifier
Authors: Gao Yan-Qi  , Zhu Bao-Qiang  , Liu Dai-Zhong  , Peng Zeng-Yun  , Lin Zhun-Qi  ,   中国科学院上海光学精密机械研究所高功率激光物理联合实验室，上海  201800
Published: December 2020

Beam automatic alignment system is used to implement beam adjustment. Basing on the principle of matrix optics, the mathematical model for auto-alignment in four-pass amplifier is built by analyzing the properties of this system. Using this model, the scheme of beam alignment is designed, and the analytical solutions of the amounts of near field adjustment and far field adjustment are obtained, respectively.
High transmission of slow light in the photonic crystal waveguide bends
Authors: Du Xiao-Yu  , Zheng Wan-Hua  , Zhang Ye-Jin  , Ren Gang  , Wang Ke  , Xing Ming-Xin  , Chen Liang-Hui  ,   中国科学院半导体研究所纳米光电子实验室,北京  100083
Published: December 2020

We present the research on the transmission characteristic of slow-light-mode in the photonic crystal line-defect waveguide bends on SOI. After optimizing the structure parameters in the vicinity of the bends, the normalized transmission efficiency of slow-light-mode through the photonic crystal 60 degree and 120 degree waveguide bends are as high as 80% and 60% respectively, which are 10 times higher than that in the undeformed case. To slow down light further, we design novel coupled cavity waveguide bend structures with high qulity-factor. High normalized transmission efficiency of 75% and low group velocity of c/170 (c is the light velocity in vacuum) are realized. These results are beneficial to enhance the slow light effect of photonic crystal structures and improve the miniaturization and integration of photonic crystal slow light devices.