bluuebunny/crossref_metadata_2025 huggingface dataset:
The mechanism of noise propagation in typical building blocks of biochemical reaction networks
Authors: Chen Ai-Min  , Yuan Zhan-Jiang  , Zhang Jia-Jun  , Zhou Tian-Shou  ,   (1)中山大学数学与计算科学学院,广州  510275; (2)中山大学数学与计算科学学院,广州  510275；中山大学生命科学学院,广州  510275
Published: December 2020

Intracellular processes of live organisms, which can be described by sets of biochemical reactions, are inherently stochastic, where the fluctuations in molecule abundance inside the cell play a crucial role in the cellular growth and development. For typical building blocks of biochemical reaction networks （including signal transduction networks and metabolic networks）, this paper first gives a unified formulation and then presents a general mechanism of noise propagation by applying the linear noise approximation theory. The main results show that: there is noise propagation in signaling transduction pathways and the noise intensity satisfies noise sum rule, and there is no noise propagation in metabolic pathways and the distributions of the steady state molecules mutually independent. The analytical results lay a theoretical foundation for understanding the intracellular processes.
Comparison of characteristics of moving detrended fluctuation analysis with that of approximate entropy method in detecting abrupt dynamic change
Authors: He Wen-Ping  , Wang Qi-Guang  , Wu Qiong  , Zhang Wen  , Zhang Yong  ,   (1)国家气候中心，北京  100081; (2)南京邮电大学通达学院，南京  210003; (3)扬州大学物理科学与技术学院，扬州  225002; (4)中国气象科学研究院，北京  100081
Published: December 2020

Approximate entropy （ApEn） is well known to be an effective abrupt change detection method in dynamic structure. Based on this, we compare the performances between the moving detrended fluctuation analysis （MDFA） and ApEn in detecting abrupt dynamic change. The results show that the MDFA results almost do not depend on length of subseries, and while the ApEn could identify dynamic structure to some extent but still depends on the length of subseries. At the same time, there exists a huge drift for the ApEn results which means the actual time-instants of abrupt change dont coincide with the detected one. Therefore, compared with ApEn, MDFA is more suitable to be used to detect abrupt dynamic change, and the advantage of MDFA is obvious.
Stochastic resonance of a damped linear oscillator
Authors: Jin Yan-Fei  , Hu Hai-Yan  ,   (1)北京理工大学力学系,北京  100081; (2)北京理工大学力学系,北京  100081；南京航空航天大学振动工程研究所,南京  210016
Published: December 2020

The stochastic resonance is studied for a damped linear oscillator subject to both parametric excitation of random noise and external excitation of periodically modulated random noise. By means of the Shapiro-Loginov formula, the expressions of the first-order and the second-order moments are obtained for the system response. It is found that there exist conventional stochastic resonance, bona fide stochastic resonance and stochastic resonance in a broad sense in the system. When the noise intensity ratio R≥1, the stochastic multi_resonance is found in the system. Moreover, the numerical results of power spectrum density of system response are presented to verify the analytic results.
Fuzzy impulsive control of chaos in permanent magnet synchronous motors with parameter uncertainties
Authors: Li Dong  , Wang Shi-Long  , Zhang Xiao-Hong  , Yang Dan  ,   (1)重庆大学机械传动国家重点实验室，重庆  400030; (2)重庆大学机械传动国家重点实验室，重庆  400030；重庆大学数理学院，重庆  400030; (3)重庆大学软件学院，重庆  400030
Published: December 2020

In this paper, the Takagi-Sugeno（T-S） fuzzy impulsive control model for PMSMs with parameter uncertainties is established via the T-S modeling technique and impulsive technique. Based on the new model, the control conditions of asymptotical and exponential stability for PMSMs with parameter uncertainties have been derived by Lyapunov method and matrix analysis. An illustrative example is also given to show the effectiveness of our results. Compared with the existing results, the obtained results exhibit certain advantage.
Experimental investigation on chaotic behaviors in loss-modulated erbium-doped fiber-ring lasers
Authors: Liu Yue  , Zhang Wei  , Feng Xue  , Liu Xiao-Ming  ,   清华大学电子工程系，北京  100084
Published: December 2020

Chaotic behaviors in loss-modulated erbium-doped fiber-ring lasers are reported. In a single-frequency loss-modulated erbium-doped fiber-ring laser, the coexistence of period-doubling bifurcation and intermittency routes to chaos is observed by changing the modulation frequency or the modulation voltage. The results are in agreement with those in an erbium-doped fiber-ring laser subjected to pump modulation. Dual-frequency loss-modulated erbium-doped fiber-ring lasers are proposed. When the value of the frequency ratio is approximately equal to the gold mean and the silver mean, respectively, the transition to chaos via quasiperiodicity is found when the modulation voltage is increased. The modulation voltages for the transition are different for the varied values of the frequency ratio.
Chaotic control of Hindmarsh-Rose neuron by delayed self-feedback
Authors: Yu Hong-Jie  , Tong Wei-Jun  ,   上海交通大学船建学院工程力学系，上海  200240
Published: December 2020

The control problems of chaotic dynamical patterns of single Hindmarsh-Rose neuron model are studied by using delayed feedback self-control method. Taking gain factor and time delay as controlling parameters respectively, in some ranges of the combination of gain factor and time-delay, we find that the chaotic burst pattern of inter-spike interval sequences of H-R neuron can be controlled to a single_spike period, double_spikes period, 3_or 4_spikes period pattern or multi-period of these patterns for inter-spike interval as the results of numerical simulation analysis. Choice of delay is in-dependent and doesn't rely on the period of unstable periodic orbits embedded within chaotic attractor. The chaotic burst orbit will be controlled to a certain type of periodic patterns of inter-spike interval automatically.
Anisotropic diffraction pattern formation from a nematic liquid crystals film induced by low-power linearly polarized beam
Authors: Ren Chang-Yu  , Sun Xiu-Dong  , Pei Yan-Bo  ,   (1)哈尔滨工业大学物理系,哈尔滨 150001; (2)哈尔滨工业大学物理系,哈尔滨 150001；黑龙江科技学院数力系,哈尔滨 150027
Published: December 2020

Anisotropic diffraction patterns were observed on far-field screen induced by a weak (0.16 W/cm2) linearly polarized collimated beam passing through a homeotropic C60-doped nematic liquid crystal (5CB) cell. Based on orientational photorefractive effect, two-wave coupling experiment was carried out to induce liquid crystal molecule re-orientation. The form of space-charge field with the Gaussian distribution induced by the Gaussian beam incident on the sample is investigated. The outline of far-field diffraction pattern is concentric ring, and shows symmetrical gaps in the direction perpendicular to the direction of polarization of light. In addition, diffraction pattern changes when the polarization of the incident light is changed, effective nonlinear index coefficient is n20.3 cm2/W. The results showed that our theoretical analyzsis was consistent with the observed experimental phenomena.
Saddle-node bifurcation control of a spring pendulum with single-frequency excitation
Authors: Xiao Han  , Tang Jia-Shi  , Liang Cui-Xiang  ,   (1)湖南大学力学与航空航天学院，长沙  410082; (2)宁波大学建筑工程与环境学院，宁波  315211
Published: December 2020

Spring pendulum under single-frequency excitation can be described by a group of very complicated nonlinear equations. The paper studies the amplitude of the spring pendulum, and feedback controllers are designed. Analytic method is used to obtain the control equation of amplitude, the relationship function between control parameter and amplitude is also abtained,which may act as an implementation of feedback control method for saddle-node bifurcation control, and also brings multi-scale method to numerical calculation of multiple-degree-of-freedom nonlinear systems.
Refraction of reaction-diffusion plane wave for different diffusion coefficients
Authors: Lü Yao-Ping  , Gu Guo-Feng  , Lu Hua-Chun  , Dai Yu  , Tang Guo-Ning  ,   广西师范大学物理与电子工程学院，桂林  541004
Published: December 2020

The effect of diffusion on the refraction of plane wave in two-dimensional reaction-diffusion system described by complex Ginzburg-Landau equation are numerically investigated. We derive the refractive index of plane wave from Snell's law. The numerical and theoretic results show that the refraction of plane wave in a simple purely diffusive system obeys Snell's law, i.e, diffusion only impacts the refractive index of plane wave. However, the refraction of plane wave in reaction-diffusion system obeys Snell's law only for proper diffusion coefficients and system parameters. These results show that diffusion impacts the refraction law and refractive index.
The fractal measurement of aerosol equivalent volume based on counting signal
Authors: Yang Juan  , Lai Xiao-Ming  , Peng Gang  , Bian Bao-Min  , Lu Jian  ,   南京理工大学信息物理与工程系，南京  210094
Published: December 2020

The conception of mass subset is proposed for aerosol which also has been extended to the equivalent mass subset corresponding to counting signal channel. According to statistics, the fractal measurement model of aerosol's equivalent volume for counting signal is established. Due to the aerosols' shape distribution of different mass subsets showing the statistical self-similar character, the calculating formula is given for aerosol equivalent mass of signal channels in the process of aerosol mass measurement. Based on this, the theoretical basis is founded for aerosol mass measurement by using counting method.
Study on the choosing of new SBS medium perfluoro-compound for phase conjugation mirror and optical limiter
Authors: Gong Sheng  , Hasi Wu-Li-Ji  , Lü Zhi-Wei  , Dong Fen-Li  , Lin Dian-Yang  , He Wei-Ming  , Zhao Xiao-Yan  , Fan Rui-Qing  ,   哈尔滨工业大学光电子技术研究所，哈尔滨  150001
Published: December 2020

In this paper, new stimulated Brillouin scattering (SBS) medium of perfluoro-compound with low absorption and high power-load are reported. The choosing of medium for conjugation mirror (PCM) and optical limiting are discussed respectively, and validated in the Nd: YAG Q-switched laser system. The results indicate that medium with small molecular weight, low kinematic viscosity and large gain coefficient should be chosen for SBS PCM; however, medium with large molecular weight, great kinematic viscosity and small gain coefficient is needed in the optical limiting. The discovery of the new medius diversifies the SBS media and the medium choosing rules provide a guide to the application the new medium.
Study on structure characteristics of MgO molecule under external electric field
Authors: Huang Duo-Hui  , Wang Fan-Hou  , Min Jun  , Zhu Zheng-He  ,   (1)四川大学原子与分子物理研究所，成都  610065; (2)宜宾学院计算物理重点实验室，宜宾  644007; (3)宜宾学院计算物理重点实验室，宜宾  644007；宜宾学院物理与电子工程系，宜宾  644007
Published: December 2020

The influence of external electric field ranging from -003 to 003 a.u. on the equilibrium geometry, HOMO energy level, LUMO energy level, energy gap, harmonic frequency and infrared intensity of MgO ground state molecule is investigated by employing the density functional methods （B3LYP） with basis sets 6-311+G（2DF）. The results show that the LUMO energy level, energy gap and harmonic frequency decrease, but the total energy increases with increasing external field. The bond length is proved firstly decreasing, then increasing, however, the HOMO energy level is proved firstly increasing, then decreasing with increasing external field. The maximum of HOMO energy level and minimum of bond length are -021765 a.u. at F=001 a.u. and 017397 nm at F=002 a.u, respectively. The external electric field has effect on excitation energies, oscillator strengths and the position and intensity of infrared spectrum.
First-principles calculation of the transport properties of silicon-carbon （Si-C） and alumium-nitrogen （Al-N） nanowires
Authors: Chen Xiao-Chun  , Yang Jun  , Zhou Yan-Hong  , Xu Ying  ,   (1)赣南医学院信息工程学院，赣州  341000; (2)江西蓝天学院公教部数理教研室，南昌  330098; (3)江西蓝天学院京东校区机电工程系，南昌  330029; (4)江西师范大学物理与通信电子学院,南昌  330022
Published: December 2020

We investigate the transport properties of oue dimensional silicon-carbon ［（SiC）n］ and alumium- nitrogen ［（Al-N）n］ nano-wires coupled to two Al（100） electrodes based on a recently developed ab-initio nonequilibrium Green function formalism.The equilibrium conductance of silicon-carbon and alumium-nitrogen nano-wires decrease with the length of wires. The charge transfer of silicon-carbon increases monotonically with the the length of wires. On the contrary, the charge transfer of alumium-nitrogen nano-wire decreases monotonically with the increasing length of wires. The charge transfer changes almost linearly with increasing gate-voltage for both nano-wires and the variation of the equilibrium conductance is different for the wires. With the increase of the gate-voltage, both nano-wires might be good candidates for molecular switch, especially the （AlN）5 nano-wires.
Theoretical calculation of the partial cross section for He-HF（DF,TF） collision system
Authors: Wang Rong-Kai  , Yu Chun-Ri  , Shen Guang-Xian  , Gong Lun-Xun  , Yang Xiang-Dong  ,   (1)安庆师范学院物理与电气工程学院，安庆  246133; (2)贵州师范大学化学与材料科学学院，贵阳  550001；四川大学原子与分子物理研究所，成都  610065; (3)贵州师范大学物理与电子科学学院，贵阳  550001；贵州师范大学原子与分子物理研究所，贵阳  550001; (4)贵州师范大学物理与电子科学学院，贵阳  550001；贵州师范大学原子与分子物理研究所，贵阳  550001；四川大学原子与分子物理研究所，成都  610065; (5)四川大学原子与分子物理研究所，成都  610065
Published: December 2020

The interaction potentials of the He-HF（DF,TF） van der Waals complexes have been obtained by center of mass transformation and then employing Murrell-Sorbie potential function to fit the accurate interaction energy data, which have been computed at symmetry-adapted perturbation theory （SAPT） level. The close coupling calculation of the partial cross sections for collision of He with HF（DF,TF） is performed by employing the fitted interaction potential. This calculation is performed for incident energies from 30 meV to 120 meV, and the information of the elastic, inelastic and total partial cross sections has been obtained. Further, the change tendency and character of the partial cross sections are discussed, and the ranges of effective interaction of the beginning of elastic and inelastic scattering have been determined for He-HF（DF,TF）collision system.
Density functional theory study of SimCn （m+n≤7） clusters
Authors: Li Bing  , Yang Chuan-Lu  , Qi Kai-Tian  , Zhang Yan  , Sheng Yong  ,   (1)鲁东大学物理与电子工程学院，烟台  264025; (2)四川大学材料科学与工程学院，成都  610065
Published: December 2020

Possible geometrical structures and relative stability of SimCn （m+n≤7） clusters are studied by using the hybrid density functional theory （B3LYP） with 6-31G*basis sets in this article. For the most stable isomers of SimCn （m+n≤7） clusters, the binding energy per atom （Eb）, second difference in energy （Δ2E） and HOMO-LUMO gaps （Eg） et al. are analyzed. The calculated results show that: with increasing of the number of atoms the structure of SiC binary clusters transform linear into planar, and then into a three-dimensional structure. When the atomic　number is less than 5, all clusters have planer structure except for Si5 and Si4C. With the increase of C atom, the average binding energy of SimCn （m+n≤7） clusters increases, which means that clusters of “rich C" are more stable than clusters of “rich Si", and Sin clusters with C doping can increase the stability. Cn, SiCn and Si2Cn clusters show clearly “odd-even" oscillation and the “magic number" effect, and Si2C,Si3C, Si5C,SiC2,Si3C2, Si4C2 and SiC4 clusters are more stable than other clusters.
Density functional calculation of the geometric and magnetic properties of MPb10（M=Ti，V，Cr，Cu，Pd） clusters
Authors: Yang Jian  , Wang Ni-Ying  , Zhu Dong-Jiu  , Chen Xuan  , Deng Kai-Ming  , Xiao Chuan-Yun  ,   南京理工大学应用物理系，南京  210094
Published: December 2020

The geometric and magnetic properties of MPb10 （M=Ti，V，Cr，Cu，Pd）clusters with four probable isomers have been studied using the generalized grandient approximation based on density functional theory. It was found that the D4d structures of MPb10 （M=Ti，V，Cr，Cu，Pd） have the highest binding energy and largest energy gaps among the four possible isomers, indicating that the D4d structure is the ground statess of MPb10 cluster with high kinetical stability. The magnetism study shows that the ground states of TiPb10，VPb10 and CuPb10 clusters have 2 μB, 1 μB and 1 μB magnetic moments, respectively. For M=Ti and Cu, the magnetic ordering of MPb10 clusters is in a weak ferromagnetic arrangement between M and Pb atoms, while there is both weak ferromagnetic and weak antiferromagnetic arrangements between Cu and Pb atoms for the CuPb10 cluster. On the other hand, there is no magnetic moment in the CrPb10 and PdPb10 clusters. Thus, the magnetic properties of MPb10 clusters could be tuned by doping different transition metal atoms into Pb10 cage.
Calculations of three-dimensional frequency-domain nonlinear beam-wave reaction for helix traveling wave tubes
Authors: Hao Bao-Liang  , Xiao Liu  , Liu Pu-Kun  , Li Guo-Chao  , Jiang Yong  , Yi Hong-Xia  , Zhou Wei  ,   (1)中国科学院电子学研究所，北京  100190; (2)中国科学院电子学研究所，北京  100190；中国科学院研究生院，北京  100049
Published: December 2020

Considering the attenuation, severing, taper and magnetic admittance, the self-consistent working equations are presented, which describe the operation of 3D nonlinear beam-wave interaction for helix traveling wave tube based on periodic structure characteristic and Poynting's theorem. Using Fourier transform from time-dependent current to ac current consisting of a series of wave frequencies, the space fields are obtained through weighing charge particles to fixed meshes with the help of particle_in_cell technique. The model also computes 3D electronic tracks and helix interception current, the electronic energy spectrum of spent beam are represented, which is helpful for designing multistage depressed collector （MDC）. Calculation of Ku-band TWT in IECAS was shown to be in better agreement with experiment, including output power and analysis of MDC.
Geometric optics analysis on self-reconstruction of the nondiffracting beam generated from an axicon
Authors: Wu Feng-Tie  , Jiang Xin-Guang  , Liu Bin  , Qiu Zhen-Xing  ,   华侨大学信息科学与工程学院,泉州  362021
Published: December 2020

Self-reconstruction of the nondiffracting beam generated from an axicon was analyzed for the first time based on the geometrical optics and the formation principle of self-reconstruction was well explained. In the Fresnel approximation, beam transmission characteristics were described well using the theory of Fresnel diffraction. But the approximation condition will not satisfy in the quite little distance after beam passing through the obstacle and the diffraction theory is no longer suitable. In such case, geometrical optics can be used to describe the beam transmission characteristics. In this paper, self-reconstruction of the nondiffracting beam generated from an axicon was analyzed in detail based on the geometrical optics. Simulation and experimental observation of the self-reconstruction characteristic are presented. The experimental results agree with the theoretical analysis.
A method to analyze insertion loss of electroabsorption-modulator using photocurrent and power transmission vs.wavelength
Authors: Liao Zai-Yi  , Zhao Ling-Juan  , Zhang Yun-Xiao  , Bian Jing  , Pan Jiao-Qing  , Wang Wei  ,   中国科学院半导体研究所，中国科学院半导体材料重点实验室，北京  100083
Published: December 2020

A novel method to ascertain diversified factors contributing to total insertion loss in an electroabsorption modulator is presented.Only the measurement of photocurrent and power transmission vs.wavelength is needed.It's an accurate method, as shown by both theory analysis and experimental results.
Analysis for phase shifts transformation of chirped pulse from frequency-domain to time-domain based on Fourier transform
Authors: Dong Jun  , Peng Han-Sheng  , Wei Xiao-Feng  , Hu Dong-Xia  , Zhou Wei  , Zhao Jun-Pu  , Zhang Ying  , Cheng Wen-Yong  , Liu Lan-Qin  ,   中国工程物理研究院激光聚变研究中心，绵阳  621900
Published: December 2020

Based on spectral interferometry and Fourier transformation, the method that spectral phase shifts of chirped pulse are transformed to transient temporal phase shifts is investigated theoretically. The error transferring formula of phase shifts from Fourier-domain to time-domain is derived, and the temporal resolution of temporal phase shifts restricted by the spectral bandwidth of reference pulse is given. The transformation process of phase shifts is simulated. The results show that phase shifts obtained is characteristic of temporal change, and the spectral phase shifts error is transferred to time-domain with reduced magnitude, and it is in agreement with calculated result by the error transferring formula.
Effect of spontaneously generated coherence on transient evolution of LWI gain in an open Ladder type system
Authors: Yang Yan-Ling  , Wang Lei  , Liu Zhong-Bo  , Lu Hong-Wu  , Fan Xi-Jun  ,   (1)山东师范大学传播学院，济南  250014; (2)山东师范大学物理与电子科学学院，济南  250014
Published: December 2020

The effect of spontaneously generated coherence （SGC） on transient evolution of gain of lasing without inversion （LWI） and modulation roles of the injection rate ratio and exit rate on SGC-dependent gain in an open Ladder type three level system are studied by using the numerical solution of the density matrix motion equation of the system. It was shown that: variation of SGC strength will make the transient and final stationary gains having a considerable changing; when incoherent pumping presents, LWI gain increases with the ratio of injection rates and exit rate decreasing, however, when incoherent pumping is absent, the case is just the opposite; by choosing suitable values of SGC strength, the injection rate ratio and exit rate, we can obtain the largest transient and final stationary gain.
Study of self-similar pulse nonlinear polarization rotation mode-locked fiber laser
Authors: Deng Yi-Xin  , Tu Cheng-Hou  , Lü Fu-Yun  ,   南开大学物理科学学院，天津  300071
Published: December 2020

A numerical model for self-similar pulse nonlinear polarization rotation mode-locked fiber laser is built by utilizing coupled nonlinear Schrdinger equations （CNLSE）. In this model, the propagation of the pulse within single mode fiber is described by CNLSE. In the gain fiber, gain bandwidth and saturable gain are both considered. Other optical components which implement NPE mode-locking are modeled by transfer matrixes. According to the optimized net cavity dispersion and length of the cavity, the evolution of the pulse along the cavity is simulated. At the same time, characteristics and the typical regime of the self-similar pulse are found. The simulation results show that pulse with 7 nJ energy, 11 ps duration, linear chirped, and of parabolic shape occurs within the optimized self-similar regime. The characteristics of the laser with different dispersion are compared. The influence of the third order dispersion on the laser is simulated.
Theoretical study of ultrafast index dynamics in semiconductor optical amplifiers
Authors: Huang Xi  , Zhang Xin-Liang  , Dong Jian-Ji  , Huang De-Xiu  ,   武汉光电国家实验室,华中科技大学光电子科学与工程学院，武汉  430074
Published: December 2020

We proposed a novel extended semiconductor optical amplifier （SOA） model for applications in femtosecond pulse transmission，in which various ultrafast nonlinear effects，such as gain dispersion and group velocity dispersion were taken into account. We analyzed the refractive index in response to variation of the input current and the length of SOA. Furthermore，the impact of carrier density pulsation and carrier heating on the refractive index dynamics of SOA was discussed respectively. The simulation model can be applied in parameter and operation condition optimization of SOAs in order to improve their femtosecond dynamic characteristics.
Spatial weak-light ring dark solitons in an electromagnetically induced transparency medium
Authors: She Yan-Chao  , 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 using multiple-scale method，we analytically study the nonlinear dynamical properties of an electromagnetically induced transparency medium with three-level atoms and a strong coupling light field. It is shown that a weak probe light beam can form spatial weak-light dark solitons. When it propagates along axial direction，the dark soliton will transforms into a steady spatial weak-light ring dark soliton，which results from the balance of the interplay between beam diffraction and refractive nonlinearity.
Tunable effects of connective dendritic left-handed metamaterials based on electrorheological fluids
Authors: Luo Chun-Rong  , Wang Lian-Sheng  , Guo Ji-Quan  , Huang Yong  , Zhao Xiao-Peng  ,   西北工业大学电流变技术研究所，西安  710072
Published: December 2020

We experimentally studied the tunable effects of connective dendritic left-handed metamaterials based on electrorheological fluids. Three influencing factors-the distance of electrodes，the permittivity of embedding media，and the intensity of applied electric fields-are discussed respectively. The experimental results show that the distance of electrodes exhibits an important effect on the transmission peak of the samples. The left-handed transmission peak shifts to lower frequency when the electrorheological fluids infiltrate. Moreover，by changing the intensity of electric field，the left-handed transmission peak can be modulated actively，and the maximum shift is up to 140 MHz.
Multiband negative index metamaterials at optical frequencies
Authors: Tang Shi-Wei  , Zhu Wei-Ren  , Zhao Xiao-Peng  ,   西北工业大学电流变技术研究所，西安  710072
Published: December 2020

Based on the fishnet negative index metamaterials （NIMs） of circular-shaped holes operating at optical frequencies，the influence of modifying the hole shape is studied using the commercial software package CST Microwave studio. Numerical simulations show that，even a tiny modification may lead to broadening of the negative refractive band. So we designed two fishnet NIMs of the gradient holes and half-global holes. Compared with the fishnet NIMs of circular-shaped holes，these two structures can realize negative refraction at multi-frequency bands，and the resonance frequencies exhibit an obvious red-shift. We present a chemical technique for preparing the fishnet NIMs of half-global holes，which is a simple and feasible way to realize multiband negative index metamaterials at optical frequencies.
The influence of the material dispersion on the dual-peak resonance effect
Authors: Deng Chuan-Lu  , Gu Zheng-Tian  ,   上海理工大学理学院光电功能薄膜实验室，上海  200093
Published: December 2020

Based on rigorous coupling theory，the influence of the dispersion of the core，cladding，film and surrounding material on the dual-peak resonance effect is studied. The result shows that the theoretical model which considers both the core and cladding material dispersion is necessary and feasible. Further，the influence of the material dispersion on the transmission characteristics of LPFG is analyzed for different film parameters. The deviation value between the dual resonant peaks is calculated before and after considering the material dispersion. The result shows that the deviation value is 1.5—2 nm and 6.5—7.5 nm, respectively. Finally，the influence of the material dispersion on the sensor sensitivity is studied for the dual-peak LPFG sensor. The result indicates that the minimum resolution for the film refractive index is 10-8，and the contour line figure after considering the material dispersion supplies accurate parameter combinations in the design of this kind of sensor.
Neutron flux measurement and analysis in the HT-7 deuterium plasma
Authors: Zhong Guo-Qiang  , Hu Li-Qun  , Zhu Yu-Bao  , Lin Shi-Yao  , Chen Jue-Quan  , Xu Ping  , Duan Yan-Min  , Lu Hong-Wei  ,   中国科学院等离子体物理研究所，合肥  230031
Published: December 2020

Fusion neutron and photon neutron producing behavior in the deuterium plasma discharge have been studied on HT-7 superconductive tokamak device by BF3 and 3He proportional ionization chamber implementing the fast time respond neutron flux measurement system. Typical time resolved neutron flux signals have been analyzed in connection with gamma and hard X-ray diagnostic data in the cases of ohmic discharge and lower hybrid wave discharge. Data analysis show that many neutrons are produced by D-D fusion reaction when high-power lower hybrid wave was employed to heat the plasma.
Numerical simulation of the breakdown on HPM dielectric surface
Authors: Cai Li-Bing  , Wang Jian-Guo  ,   (1)西北核技术研究所，西安  710024; (2)西北核技术研究所，西安  710024；西安交通大学电子与信息工程学院，西安  710049
Published: December 2020

This paper presents the electrostatic PIC-MCC model for simulating the breakdown of dielectric surfaces illuminated by high-power microwave，and the processes of multipactor and collisional ionization in the case of vacuum and different pressures are simulated by using the code developed by ourselves. The numerical results show that the multipactor effect is the main source of electrons，and the number of the electrons oscillates in the time domain at twice the rf frequency in the case of vacuum and low pressures. In the case of high pressure，the collisional ionization is the main source of electrons.
Phase configuration and stability in the nanocrystalline Sm-Co system
Authors: Xu Wen-Wu  , Song Xiao-Yan  , Li Er-Dong  , Wei Jun  , Li Ling-Mei  ,   北京工业大学材料学院新型功能材料教育部重点实验室，北京  100124
Published: December 2020

A thermodynamic model that describes the thermal properties of the compound phases in the nanocrystalline （NC） alloy systems has been developed，which provides quantitative predictions on the stabilities and transition features of different phases. By using the NC Sm-Co alloy system as an example，the temperature dependence of the mole Gibbs free energy of the NC alloy phases with different excess volumes in the nano-grain boundary regions were provided. Based on the model calculations，the relative stability of different phases and the phase transition rules in the NC Sm-Co system were analyzed. It was shown by the calculation results that near the room temperature，some of the NC alloy phases，whose mole Gibbs free energy values change from negative to positive due to the decrease of the nano-grain size，will transform into stable NC alloy phases. This is distinctly different from the phase transformation features in the coarse-grained alloy systems，whose thermodynamic properties are only dependent on the temperature. The experimental results on the phase configuration and the phase stability obtained from the prepared NC Sm-Co alloy confirmed the theoretical predictions of the present thermodynamic model.
The ignition-proof effect of Ca and Be in Mg alloys
Authors: Guo Yu-Fu  , Li Rong-De  , Liu Gui-Li  ,   沈阳工业大学材料科学与工程学院，沈阳  110023
Published: December 2020

The atomic cluster models of α-Mg，liquid Mg and the interface between liquid/solid have been founded. The environment-sensitive embedding energy of Ca and Be in α-Mg，liquid Mg，liquid/solid interface has been calculated by recursion method. The atomic affinity energy between Mg，Ca，Be with O has been defined and calculated. The calculated results show that the solid solubility of Ca and Be is very small in α-Mg，because of their higher environment-sensitive embedding energy leads to instability in α-Mg crystal. The Ca and Be diffuse in to the liquid Mg, which has lower environment-sensitive embedding energy than the solid，and congregate on the surface of liquid Mg as the alloys solidify. Because the atomic affinity energy of Ca-O and Be-O is lower than Mg-O，The Ca and Be aggregating on the surface of liquid Mg will priorly combined with O，forming compact oxides of Ca，Be and alloys of elements，which prevent Mg alloys from burning.
First principles study of H2O molecule adsorption on Fe（100）, Fe（110） and Fe（111） surfaces
Authors: Zhao Wei  , Wang Jia-Dao  , Liu Feng-Bin  , Chen Da-Rong  ,   清华大学摩擦学国家重点实验室，北京  100084
Published: December 2020

The adsorption of H2O on Fe（100）, Fe（110） and Fe（111） crystal surfaces were studied by first principles. The calculation results indicate that H2O monomers bind preferentially at top sites and lie nearly flat on the three crystal surfaces. The results of adsorption energy and geometry structure show that the effect of H2O adsorbed on three iron crystal surfaces is different. The strongest interaction occurred between H2O and Fe（111） crystal surface and the weakest interaction is between H2O and Fe（110） crystal surface. Such relationship is related to the different surface atoms density. The similar conclusion can be drawn from the calculation results of electronic structure and Mulliken analysis. The Mulliken analysis also indicates that when H2O is adsorbed on the iron surface, charge exchange between O atom and Fe atom make the iron surface negatively charged and reduce the surface potential, which promote the electrochemical corrosion of iron surfaces.
Optical properties of amorphous GaN films deposited by sputtering
Authors: Jia Lu  , Xie Er-Qing  , Pan Xiao-Jun  , Zhang Zhen-Xing  ,   兰州大学物理科学与技术学院，兰州  730000
Published: December 2020

The amorphous GaN（a-GaN） films are deposited by direct current planar magnetron sputtering in different compositions of argon-nitrogen mixtures. X-ray diffraction patterns and the Raman spectra indicate that the films have amorphous structures. Spectroscopic ellipsometry shows that the refractive index and the film thickness increase with increasing argon content. The UV-Vis spectra indicate that the band gap of the film deposited without argon is 3.90eV, which is much larger than that of crystalline GaN （c-GaN）, owing to the structural disorder. When the films are deposited at higher argon content, the band gap becomes much smaller （2.80—3.30eV）, probably because of more excessive Ga in the films. The band tails extending to lower energies are modeled. Two parameters representing the energy broadening of the electronic transitions and the width or slope of the exponential tail are 0.257—0.338eV and 1.44—1.89?eV, respectively, which are higher than that of c-GaN films, indicating that a-GaN films have wider absorption tails than the c-GaN films. Photoluminescence peak at 360 nm observed at room temperature comes from band_to_band emission.
Calculation of field enhancement factor of gated nanowire
Authors: Lei Da  , Wang Wei-Biao  , Zeng Le-Yong  , Liang Jing-Qiu  ,   (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；中国科学院研究生院，北京  100049; (3)中国科学院长春光学精密机械与物理研究所应用光学国家重点实验室，长春  130033
Published: December 2020

To estimate the field enhancement factor of the gated nanowire, the image charge model of floating sphere between parallel gate and cathode plates is proposed. The field enhancement factor of the gated nanowire is expressed by β=1/2（3.5+L/r0+W）, where L and r0 are the length and tip radius of nanowire, respectively, and W is a function of the gate-hole radius R, gate-cathode distance d and the geometrical parameters of the nanowire. The calculation results show that the influence of the aspect ratio of the nanowire on the enhancement factor is remarkable, i.e., the enhancement factor increases rapidly with the increase of the length and top curvature of the nanowire. Furthermore, the enhancement factor decreases with the increase of the gate-cathode distance and is equal to β0=3.5+L/r0 when the gate-cathode distance tends to infinite. The smaller the gate-hole radius, the larger the enhancement factor, and the enhancement factor will be equal to β=β0+1.202（L/d）3 when the gate-hole radius tends to zero.
Spin polarized current transport and charge polarization effect in ferromagnetic GaMnN resonant tunneling diode
Authors: Tang Nai-Yun  ,   上海电力学院,上海  200090
Published: December 2020

The spin-polarized tunneling current transport through a ferromagnetic GaMnN resonant tunneling diode is investigated theoretically. Two distinct spin splitting peaks can be observed in the current-voltage characteristic. Spin splitting peaks and the spin polarization decrease and then disappear with increasing temperature. When charge polarization effect is considered for the GaN heterostructure, the spin-down resonant current peak becomes enhanced significantly and spin polarization is also increased accordingly. A highly spin polarized current can be obtained at a certain polarization charge.
The effect of back-barrier layer on the carrier distribution in the AlGaN/GaN double-heterostructure
Authors: Zhang Jin-Cheng  , Zheng Peng-Tian  , Dong Zuo-Dian  , Duan Huan-Tao  , Ni Jin-Yu  , Zhang Jin-Feng  , Hao Yue  ,   西安电子科技大学微电子学院，宽带隙半导体技术国防重点学科实验室，宽禁带半导体材料与器件教育部重点实验室，西安  710071
Published: December 2020

The one-dimensional self-consistent simulation of the band diagram and carrier distribution of the AlGaN/GaN double hetero-structure is firstly carried out to research the effect of the thickness and Al content of the AlGaN back-barrier layer on the carrier distribution. Then the AlGaN/GaN double hetero-structure materials with different back-barrier layers were grown by low-pressure MOCVD method on c-plane sapphire substrate. The mercury probe CV measurement was carried out to verify the results of theoretical simulation. The results of theoretical simulation and experiment both indicate that with the increase of Al content and thickness of the AlGaN back-barrier layer, the two-dimensional electron Gas density becomes low in the main channel and high in the parasitic channel gradually.The increase of Al content and thickness of the AlGaN back-barrier layer effectively enhances the two-dimensional electron Gas confinement but simultaneity produces higher-density parasitic channel. So a compromise has to be made between the improvement of the two-dimensional electron Gas confinement and the restraint of the carrier density in parasitic channel in designing the double heterostructure.
Energy dissipation during cooling process in granular gas under gravity
Authors: Hu Guo-Qi  , Tu Hong-En  , Hou Mei-Ying  ,   (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；宁波工程学院理学院，宁波  315016
Published: December 2020

Granular gas is a far from equilibrium discrete system. Due to intrinsic energy dissipation, the system will cool down when there is no energy input. In this paper we report our experimental study on this cooling process in a quasi 2-D granular gas system under gravity. By using fast video photography, particles excited by air flow from the bottom of the container were traced during cooling. The cooling process contains two regimes: One of them is when inelastic collisions of particles in the gas phase is dominant. In this regime condensation at the bottom will occur at a rate determined by three factors, namely the constant piling rate α, granular temperature T and vertical mass velocity vg. The second regime is near the end of the cooling, the energy dissipation is mainly contributed from the surface area of the condensation region. This time the piling rate and the dissipation rate both show exponential dependence.
Influence of Ta and TaN bottom electrodes on electrical performances of MIM capacitors with atomic-layer-deposited HfO2 dielectric
Authors: Xu Jun  , Huang Yu-Jian  , Ding Shi-Jin  , Zhang Wei  ,   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

Based on atomic-layer-deposited high permittivity HfO2 films on both Ta and TaN substrates, we compare the influence of different bottom electrodes on electrical performance of metal-insulator-metal （MIM） capacitors. The experimental results indicate that the TaN bottom electrode can give higher capacitance density （7.47?fF/μm2） and smaller voltage coefficients of capacitance （356ppm/V2 and 493ppm/V）, which are attributed to the high quality interface between TaN bottom electrode and HfO2 dielectric films. Moreover, a low leakage current of ～5×10-8A/cm2 at 3V is achieved for both types of capacitors, and TaN bottom electrode-based MIM capacitors exhibit higher breakdown field. Finally, the conduction mechanism of the TaN-based capacitor is studied, showing a Schottky emission at room temperature.
Magnetic-electric controllable spin transport in semiconductors superlattic
Authors: Wang Ru-Zhi  , Yuan Rui-Yang  , Song Xue-Mei  , Wei Jin-Sheng  , Yan Hui  ,   (1)北京工业大学材料学院薄膜实验室,北京  100124; (2)首都师范大学物理系 北京  100037
Published: December 2020

By solving electron tunneling problem in semiconductor superlattice, the magnetic-electric controllable spin transport is theoretically investigated.The results show that, with magnetic modulation only,the spin transmission will separate, and with the magnetic filed increasing,the conductance polarization is enhanced and its peaks are widened. By both magnetic and single interval electric barrier modulation,the conductance polarization will be evidently improved; and at the same time,there are two distinct transport regions for different electric modulation, in which the down-spin electron obeys different change rules with different electric filed.However,applying electric modulation at intervals of two periods on the magnetic superlattic,it is noticed that the critical behavior of electron spin transport disappears,and the resonant peak of the conductance polarization also degenerates in the high energy region.These results show that the symmetry is an important factor for spin transport in the semiconductor superlattice.
Properties of spin transport of double quantum rings with structures of ferromagnet/ semiconductor/ ferromagnet
Authors: Du Jian  , Li Chun-Guang  , Qin Fang  ,   承德高等民族师范专科学校物理系,承德  067000
Published: December 2020

Spin-dependent transport through ferromagnetic/semiconductor/ferromagnetic double quantum rings is studied in this paper. It is found that the average value of the spin-dependent electron transmission coefficient of the double quantum ring is larger than that of the single quantum ring under the condition of zero magnetic flux and antiparallel configration of the ferromagnetic electrodes. When the magnetization directions of the ferromagnetic electrodes are parallel, the average tunneling coefficient of the spin-down electrons in double quantum rings increases distinctly. When the Rashba spin-orbit coupling is considered, the average tunneling coefficient of the spin electrons in double quantum rings is bigger than that in single quantum ring. The applied magnetic field enhences the tunneling coefficient. The δ barrier of the double quantum rings suspresses the tunneling of the electron. The tunneling coefficient decreases monotonically and nonlinearly with the δ barrier strength Z increasing.
Influence of pillar-and hole-patterned sapphire substrates on MOVPE grown GaN bulk and LED structures
Authors: Jiang Yang  , Luo Yi  , Wang Lai  , Li Hong-Tao  , Xi Guang-Yi  , Zhao Wei  , Han Yan-Jun  ,   清华大学电子工程系,集成光电子学国家重点实验室,北京  100084
Published: December 2020

Bulk GaN material and LED structures on pillar-patterned sapphire substrates （PSS-p） and hole-patterned sapphire substrates （PSS-h） were grown by MOCVD and the characteristic was compared in detail. X-ray diffraction and atomic force microscope measurements show a better crystal quality and surface morphology of GaN on PSS-h than that of GaN on PSS-p, which is due to the lateral growth of GaN on PSS-h observed from cross-sectional scanning electron microscopy. Furthermore, the output power of LED on PSS-p and PSS-h with 20 mA injection current are 46% and 33% higher than LED on conventional sapphire substrate, respectively. The temperature-dependent photoluminesence measurements indicate that the internal quantum efficiencies of all samples are quite close. Therefore, the airgaps between GaN and PSS-h act against the improvement of light extraction efficiency.
Photon’s Berry phase under background of plasma waves
Authors: Ge Lin  , Ji Pei-Yong  ,   (1)上海大学物理系,上海  200444; (2)上海大学物理系,上海  200444；上海市星系与宇宙学重点实验室,上海  200234
Published: December 2020

Electron plasma waves driven by high-power laser pulses are described as an effective geometric background by means of optical metrics. The motion equations of probe photons and Hamilton expression for photons under the background of electron plasma waves are derived via Maxwell equations in the curved spacetime. The contribution of electron plasma wave to photons Berry phase is obtained and the corresponding modification to photons Berry phase in vacuum spacetime is estimated under the conditions of the present experimental facility.
Structure and magnetic properties of stress-induced martensites in ferromagnetic shape memory alloy Mn2NiGa
Authors: Ma Li  , Zhu Zhi-Yong  , Li Min  , Yu Shi-Dan  , Cui Qi-Liang  , Zhou Qiang  , Chen Jing-Lan  , Wu Guang-Heng  ,   (1)吉林大学超硬材料国家重点实验室,长春  130012; (2)中国科学院物理研究所磁学国家重点实验室,北京  100190
Published: December 2020

In-situ high pressure X-ray diffraction experiments on Heusler-type ferromagnetic shape memory alloy Mn2NiGa under pressure up to 40 GPa have been carried out by using diamond anvil cell device with synchrotron radiation source， and magnetic measurements have also been performed on uninstalled samples by using vibration sample magnetometer. At ambient pressure Mn2NiGa has body centered cubic structure. Two phase transitions in Mn2NiGa were observed during high pressure experiments. The first at about 0.77 GPa is belong to martensitic transformation, and the second at about 20 GPa is isostructural transformation between two different martensites. Meanwhile, a lot of defects and distortion of lattice were generated in martensites due to pressurization. Consequently, coercive force of stress-induced martensites rises up to 204 kA/m and it is almost ten times larger than that of thermo-induced martensites. Pressure processes also make saturation magnetization of martensites decrease rapidly, which reveals the obvious defect effect.
Magnetoelectric coupling and magnetoelectric properties of single-phase ABO3 type multiferroic materials
Authors: Zhong Chong-Gui  , Jiang Qing  , Fang Jing-Huai  , Ge Cun-Wang  ,   (1)南通大学化学化工学院,南通  226007; (2)南通大学理学院,南通  226007; (3)南通大学理学院,南通  226007；苏州大学物理科学与技术学院,苏州  215006; (4)苏州大学物理科学与技术学院,苏州  215006
Published: December 2020

The anomalies in both the dielectric constant and loss tangent occur at fixed temperature close to the magnetic ordering transition, which have been observed experimentally in multiferroic pervoskite YMnO3 and BiMnO3, indicating coupling between the magnetism and dielectric properties. In this paper, by analyzing the magnetoelectric coupling between magnetic and ferroelectric subsystems, an appropriate coupling term related to a combination of electric polarization and spin correlation is added to system Hamilton expression, Then apply the soft-mode theory for electric subsystem and mean-field approximation under Heisenberg model for magnetic subsystem,magnetoelectric properties have been investigated, including the change of polarization, dielectric constant induced by external magnetic field, and the change of magnetization induced by external electric field. We also make some qualitative comparison and analysis between our results and the experimented ones and give a reasonable interpretation of magnetoelectricity phenomenon in some multiferroic pervoskite materials.
The modeling and analysis of magnetoelectric effect in bilayer nanocomposites
Authors: Wang Lei  , Yang Cheng-Tao  , Xie Qun-Tiao  , Ye Jing-Hong  ,   电子科技大学电子薄膜与集成器件国家重点实验室,成都  610054
Published: December 2020

Based on the elasticity mechanical model, we employ the free_state bilayer magnetoelectric nano_thin film model which introduces the magnetoelectric （ME） theoretical voltage coefficient formula simply. By this way, the ME voltage coefficient of CoFe2O4/Pb （Zr0．52Ti0．48）Ｏ3 bilayer has been calculated and analyzed under the corresponding material parameters. The results show that the ME voltage coefficient is reduced significantly when the thickness of substrate increases due to the gripping effect. The optimum volume ratio of piezoelectric film and magnetoelectric film increase when the gripping effect increasing.