bluuebunny/crossref_metadata_2025 huggingface dataset:
First-principles calculation on the electronic structure and absorption spectrum of the wurtzite Zn1-xMgxO alloys
Authors: Huang Dan  , Shao Yuan-Zhi  , Chen Di-Hu  , Guo Jin  , Li Guang-Xu  ,   (1)广西大学物理科学与工程技术学院，南宁  530004; (2)中山大学光电材料与技术国家重点实验室，广州  510275
Published: December 2020

The electronic structure and absorption spectrum of the wurtzite Zn1-xMgxO(x=0, 00625, 0125, 025)　alloys have been calculated by means of the first-principles method. The doping of magnesium leads to an apparent change of the electronic structure of ZnO. The electron density of the oxygen atoms near the magnesium atom increases obviously, and the oxygen atoms transfer some of the electrons to Zn atoms nearby. This weakens the interactions between zinc and oxygen atoms, the band gap becomes broader, which has been validated by the extent of shift of Zn 4s in the same alloys. Theoretical calculation also reveals a blue shift in the absorption spectrum of Mg-doped ZnO, and the absorption edges were located at 379，366，357 and 333nm, respectively, with increasing doping of magnesium in ZnO. The results are discussed in detail.
Fabrication of ZnO nanowire-based diodes and their light-emitting properties
Authors: Wang Yan-Xin  , Zhang Qi-Feng  , Sun Hui  , Chang Yan-Ling  , Wu Jin-Lei  ,   纳米器件物理与化学教育部重点实验室,北京大学信息科学技术学院，北京  100871
Published: December 2020

A Schottky type light-emitting diode of ZnO nanowire was fabricated based on the principle of luminescence of Schottky barrier heterojunction. Driven by a voltage of above 6 V, an EL spectrum was obtained. The spectrum consisted of two peaks: one is centered at a wavelength of the ultraviolet 392nm, and the other at the visible 525nm. The mechanism of electroluminescence of this device was analyzed according to the rectifying I-V curve and the energy band structure.
Study of Rydberg states of lithium in a static electric field using B-spline functions
Authors: He Yong-Lin  , Zhou Xiao-Xin  , Li Xiao-Yong  ,   西北师范大学物理与电子工程学院,兰州  730070
Published: December 2020

The B-spline expansion technique and the method of model potential of atom have been applied to study the properties of Stark states of lithium. Our results for Stark maps, oscillator strength distributions, avoided crossing positions and widths for Li are in good agreement with other reported theoretical calculations and experimental measurement. It shows that the method we used can be applied to investigate the properties of alkali-metal atoms in external static electric field. Finally, for the first time, we obtained the evolution of the oscillator strength spectrum of Li with varying static electric field.
The adhesives strength of nanostructured AT13 ceramic coatings characterized by fractal dimension
Authors: Hua Shao-Chun  , Wang Han-Gong  , Wang Liu-Ying  , Zhang Wu  , Liu Gu  ,   (1)北京清河大楼，北京  100085; (2)第二炮兵工程学院，西安  710025
Published: December 2020

Fractal dimension has been applied to study the interface of nanostructured AT13 coatings deposited by micro-plasma spraying. The result shows that the higher the spraying current, the greater the fractal dimension and adhesive strength. Fractal dimension and adhesive strength increase firstly and then decrease with increase of Ar flow rate. Fractal dimension can be used to characterize adhesive strength of the coatings. Adhesive strength increases with rising of fractal dimension. There is a proximate linear relationship between the logarithm of adhesive strength and fractal dimension: ln(σ)=176D-262.
The relationship between FWHM and duration of single peaked GRB light curves
Authors: Deng Jia-Gan  , Huang Ren-Tang  ,   (1)广西大学物理科学与工程技术学院，南宁  530004; (2)广西民族大学物理与电子工程学院,南宁  530012
Published: December 2020

We explored the relation between FWHMs of single pulses in a sample of GRB (Gamma-Ray Burst) light curves and durations of the GRBs. Based on a sample of 108 single_peaked GRB light curves, we fitted these sample data with Kocevski, Ryde & Liang (2003) model. A sub-sample containing 59 pulses with χ2T≈BWa, where T is the duration, W is the FWHM， a and B are constants. Our result shows that there does exist a proportional correlation between the logarithm of FWHMs and the logarithm of T90 (duration containing from 5% to 95% of the total fluence of a GRB) of GRB light curves with a correlation coefficient R=072.The proportional correlation between the logarithm of FWHMs and the logarithm of T50 (duration containing from 25% to 75% of the total fluence of a GRB) is more tight with a larger correlation coefficient R=093.Our finding shows that the light curve structure is correlated to the GRB duration. A larger FWHM corresponds to a longer GRB.
The auxiliary equation for constructing the exact solutions of the variable coefficient combined KdV equation with forcible term
Authors: Taogetusang  , Sirendaoerji  ,   内蒙古师范大学数学科学学院，呼和浩特  010022
Published: December 2020

Based on the auxiliary equation method, a method of auxiliary equation of elliptic function combined with function transformation is proposed. The method is applied to constructed the Jacobi-like elliptic function exact solutions, degenerated solitary-like solutions and triangle-like function wave solutions of variable coefficient combined KdV equation with forcible term with the help of symbolic computation system Mathematica.
Parameter identification based on linear feedback control for uncertain chaotic system
Authors: Li Nong  , Li Jian-Fen  , Liu Yu-Ping  , Ma Jian  ,   (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

An adaptive control method is proposed for the synchronization of chaos systems with uncertain parameters. Based on the Lyapunov stability theory, an adaptive control law of parameters is derived to make the states of the drive system and the response system asymptotically synchronized, by which the uncertain parameters of response system are identified. To demonstrate the effectiveness of the proposed scheme, numerical simulations results are given for the Lorenz system and Chua’s circuit.
The neighbor point selection method for local prediction based on information criterion
Authors: Meng Qing-Fang  , Peng Yu-Hua  , Qu Huai-Jing  , Han Min  ,   山东大学信息科学与工程学院，济南  250100
Published: December 2020

The number of nearest neighbor points is an important parameter for the local prediction method, which has an important impact on the prediction accuracy and computation complexity of the local model. Based on the information criterion, the neighbor point selection method for the local prediction method is proposed in this paper. We illustrate this method by analyzing chaotic time series from Lorenz model and the experimental laser data- Santa Fe Data A. Simulation results show that using the proposed method to select neighbor points, the one-step and multi-step prediction accuracy of the local prediction method is good, and the computation complexity is reduced.
Stability analysis of complex networks with multi-links
Authors: Gao Yang  , Li Li-Xiang  , Peng Hai-Peng  , Yang Yi-Xian  , Zhang Xiao-Hong  ,   (1)北京邮电大学，网络与交换技术国家重点实验室，信息安全中心，北京  100876; (2)北京邮电大学，网络与交换技术国家重点实验室，信息安全中心，北京  100876；江西理工大学信息工程学院，赣州  341000
Published: December 2020

In this paper，a new idea about network split is presented according to the different nature of the network links. Time-delay has been introduced into networks to effect the split and on that a model of complex dynamical networks with multi-links has been constructed. Based on Lyapunov theory，the stability analysis of networks with multi-links is also studied. The sufficient conditions of the stability of networks with time-delay and without time-delay are respectively presented. The validility of the results are proved by numerical simulation of this paper.
Robust synchronization of a class of chaotic systems based on integral observer method
Authors: Li Xiu-Chun  , Xu Wei  , Xiao Yu-Zhu  ,   西北工业大学理学院应用数学系，西安  710072
Published: December 2020

Using the integral-observer approach, chaos synchronization is achieved for a class of chaotic systems when both the parameters and the output of the system are perturbed. Based on Lyapunov stability theory and LMI technique, we give the sufficient criterion, which can make the drive system and the response system globally exponentially synchronized. In the end, we take MLC chaotic system as an example to verify the effectiveness of the proposed method.
Projective synchronization of the fractional order unified system
Authors: Wang Xing-Yuan  , He Yi-Jie  ,   大连理工大学电子与信息工程学院，大连  116024
Published: December 2020

This paper calculates the largest Lyapunov exponent and correction dimension of the fractional order unified system when changing the system parameter, and studies the dynamical behavior of this system. Based on the stability criterion of linear systems, a new approach for constructing projective synchronization of fractional order unified system is proposed. Numerical simulations of fractional order Chen system, fractional order Lü system and fractional order Lorenz-like system are provided to demonstrate the effectiveness of the proposed scheme.
The structure and potential energy function of PdCO molecule
Authors: Kong Fan-Jie  , Du Ji-Guang  , Jiang Gang  ,   四川大学原子与分子物理研究所，成都  610065
Published: December 2020

Density functional method(B3LPY) has been used to optimize the possible structures of PdC，PdO and PdCO molecules with contracted valence basis set (LANL2DZ) for Pd atom and the AUG-cc-pVTZ basis set for C and O atoms respectively.It was found that the ground state of PdC molecule is 1Σ，whose equilibrium nuclear distance and dissociation energy are RPdC=0.17285nm and 4.919eV, respectively.The ground state of PdO molecule is 3Π with equilibrium geometry RPdO=0.18546nm and dissociation energy De=2.455eV. The ground state of the linear Pd—C≡O (C∞v) is 1Σ+ and the configuration and dissociation energy are RPdC=0.18721nm，RCO=0.11427nm and 12.563eV, respectively. At the same time， another metastable structure Pd—O≡C(C∞v) was found. Its equilibrium geometry and dissociation energy are RCO=0.11336nm， RPdO=0.23001nm and 10.937eV, respectively.The possible dissociation limit of PdCO molecule is determined.The analytical potential energy function for PdCO molecule has been obtained from the many-body expansion theory.The contour of the potential energy surface sheds light on the accurate structure and dissociative energy for PdCO molecule.Furthermore, the molecular static reaction pathway based on this potential energy function is investigated.
Quark phase transition in supernova and the effect of quark mass on the process
Authors: Lai Xiang-Jun  , Luo Zhi-Quan  , Liu Jing-Jing  , Liu Hong-Lin  ,   西华师范大学理论物理研究所,南充  637002
Published: December 2020

Based on constituent quark mass and current quark mass model, the phase transition of two-flavor quark matter to more stable three-flavor quark matter in the core of supernova is studied. It is shown that the timescale of the process is shorter than 10-8 seconds for both cases, and the smaller the quark mass (current quark mass), the quicker the process; and the equilibrium parameters, except the temperature, such as s-quark abundance, neutrino abundance and total neutrino energy in supernova core, have a slight increase compared to the former result after the conversion according to constituent quark mass model. But the values of those parameters (including temperature) increase significantly based on current quark mass model. The current quark mass will be more favorable for the success of the delayed neutrino-heating mechanism for the explosion.
Theory and method of X_ray grating phase contrast imaging
Authors: Chen Bo  , Zhu Pei_Ping  , Liu Yi-Jin  , Wang Jun-Yue  , Yuan Qing_Xi  , Huang Wan_Xia  , Ming Hai  , Wu Zi-Yu  ,   (1)中国科学技术大学物理系，合肥  230026; (2)中国科学技术大学物理系，合肥  230026；中国科学院高能物理研究所，北京  100049; (3)中国科学院高能物理研究所，北京  100049
Published: December 2020

In this work,we make a theoretical analysis of X_ray grating phase contrast imaging (XGPCI) and give an equation to show the relationship between the transmittance and the relative shift of the two gratings,which was named as the shift curve.According to this equation,we develop a new method to retrieve phase information from the experimental data in theory.Finally,we analyze the influence of the experimental setup to the resolution of the image.
Density functional theory studies on spectral properties of H3PAuPh and (H3PAu)2(1,4-C6H4)2
Authors: Jiao Yu-Qiu  , Zhao Kun  , Lu Gui-Wu  ,   中国石油大学数理系，北京  102249
Published: December 2020

The structures of the H3PAuPh and (H3PAu)2(1,4-C6H4)2 are optimized using the density functional theory for the ground states. The lowest-energy absorption spectra are calculated by the time-dependent density functional theory，and it is found that the 257.5nm line arises from 1A＇→1A＇ transition for H3PAuPh and the 307.6nm line arises from 1A→1A transition for (H3PAu)2(1,4-C6H4)2. The lowest-energy absorption spectra of the Au complexes have the nature of pπ(aromatic_nucleus)→pπ*(aromatic_nucleus)C(2p)→Au(6p) charge transfer which is accompanied by Au(5d)→Au(6p) transition character. The (H3PAu)2(1,4-C6H4)2 is approximately made up of double H3PAuPh. So the molecular orbitals of (H3PAu)2(1,4-C6H4)2 can be regarded as the compounding of the molecular orbitals of H3PAuPh. The compounding of the molecular orbitals with the reciprocities of pπ* or pπ makes the lowest-energy absorption energy of (H3PAu)2(1,4-C6H4)2 lower than that of H3PAuPh.
Density functional theory study of structures and electronic properties of XMgn (X=B, Al, n=1—12) clusters
Authors: Tian Fu-Yang  , Wang Yuan-Xu  , Jing Qun  , Tian Kai  , Luo You-Hua  ,   (1)河南大学计算材料科学研究所,河南大学物理与电子学院,开封  475004; (2)河南大学计算材料科学研究所,河南大学物理与电子学院,开封  475004;华东理工大学理学院,上海  200237
Published: December 2020

Geometry optimization and electronic properties of BMgn, AlMgn(n=1—12) clusters have been studied based on density functional theory (DFT). With the increase of the number of Mg atoms, the boron atom gradually comes into the interior of the Mgn cluster. However, the growth patterns of AlMgn clusters are similar to that of magnesium clusters. Doping of a B or Al atom makes the average binding energy higher and the stability enhanced. The atomic configuration plays a dominant role in the stability of B, Al atom doped magnesium clusters. The induction of B, Al atoms makes the NBO charge population of host magnesium clusters obviously altered. The peak of the average NBO charges population of 3p orbital of Mg atoms in AlMgn clusters is in agreement with the stability of AlMgn (n=1—12) clusters.
Investigation on vibrational levels, inertial rotation and centrifugal distortion constants of 7Li2(X1Σ+g)
Authors: Shi De-Heng  , Sun Jin-Feng  , Zhu Zun-Lüe  , Ma Heng  , Yang Xiang-Dong  ,   (1)河南师范大学物理与信息工程学院,新乡  453007; (2)河南师范大学物理与信息工程学院,新乡  453007；四川大学原子与分子物理研究所,成都  610065; (3)四川大学原子与分子物理研究所,成都  610065; (4)信阳师范学院物理电子工程学院,信阳  464000；河南师范大学物理与信息工程学院,新乡  453007
Published: December 2020

The density-functional theory (B3LYP, B3P86) and the configuration-interaction method (CCSD(T), QCISD) presented in Gaussian03 program package are employed to calculate the equilibrium internuclear distance Re, the harmonic frequency ωe and the dissociation energy De of 7Li2(X1Σ+g) under a number of basis sets. By comparison with the measurement, the conclusion is that the most accurate Re, De and ωe results (0.2698nm, 1.0487eV and 346.82 cm-1, respectively) can be obtained at the CCSD(T)/cc-PVQZ level of theory. The potential energy curve at this level is calculated over a wide internuclear separation range of 0.15 to 2.7nm at a 0.03nm step size and is fitted to the analytic Murrell-Sorbie function. With the potential obtained at the CCSD(T)/cc-PVQZ level of theory, the rest spectroscopic parameters (ωeχe, αe and Be) are calculated and the values are 2.648cm-1, 0.00702cm-1 and 0.6601cm-1, respectively, which are in excellent agreement with the experimental ones. By solving the radial Schrdinger equation of nuclear motion, the total number of 41 vibrational states has been found when J=0 for this X1Σ+g state. For each vibrational state, the vibrational level, the classical turning point and the inertial rotation constant have been computed, which are in good agreement with the experimental findings. The complete centrifugal distortion constants (Dν, Hν, Lν, Mν, Nν and Oν) are reported for the first time for the first 31 vibrational states when J=0.
Propagation of linearly polarized Gaussian beam through the compound modulated diffraction grating
Authors: Li Jian-Long  , Lü Bai-Da  ,   四川大学激光物理与化学研究所，成都  610064
Published: December 2020

A new type of diffraction grating called the compound modulated diffraction grating is proposed, which incorporates both surface relief and periodic refractive index modulation. Based on the angular spectrum representation and strict modal theory, the propagation of linearly polarized Gaussian beam through the compound-modulated diffraction grating whose characteristic size is comparable with the wavelength is studied. It is shown that the propagation of beam in each layer is different and the intensity fluctuation frequency in the compound-modulated grating is smaller than that in the conventional relief grating at the same transmission depth. Using the compound modulated grating model, the influence of surface fluctuation of the sub-wavelength_volume phase holographic grating and waist width of the incident beam on the diffraction efficiency is analyzed.
The law of the bubble motion near the wall
Authors: Zhang A-Man  , Yao Xiong-Liang  ,   哈尔滨工程大学船舶工程学院，哈尔滨  150001
Published: December 2020

Based on the assumption of potential flow, the coupled numerical model of the bubble and the wall is created and it is calculated with boundary integral method and a three-dimensional computing program is developed. The calculated result agrees with the experimental result well. Starting with the basic phenomenon of the interaction between the bubble and the wall, the dynamics of the bubble near a rigid wall is studied systematically with the program developed in this paper, including both cases of the parallel wall and the oblique wall. The relation between Bjerknes effect of the wall and the characteristic parameters is studied and the calculated results of various cases are compared and discussed with the Blake criterion based on the Kelvin-impulse theory. The analysis shows that the jet direction and the pressure on the rigid wall have close relationship with the bubble's characteristic parameters. Besides, the application range of Blake criterion is given. This paper aims to provide reference for the relevant researches on the dynamics of bubble near the wall.
Influence of spherical aberration of the thermal lens on the mode profile of a large-volume TEM00-mode resonator
Authors: Liu Chong  , Ge Jian-Hong  , Xiang Zhen  , Chen Jun  ,   浙江大学现代光学仪器国家重点实验室,杭州  310027
Published: December 2020

The spherical aberration of the thermal lens of the active media is obvious when the solid state lasers are strongly pumped. It can change the mode profile, the single-pass loss, the output power and so on, especially in a large-volume TEM00-mode resonator. The self-consistent mode is calculated using Fox-Li diffraction iterative algorithm. There are side lobes with the fundamental mode when the spherical aberration is introduced, hence the beam quality is degraded. The calculation results agree well with the experimental results. The beam filling factor plays an important role in the design of a laser system. The optimized value of the beam filling factor should be determined experimentally according to the spherical aberration.
Progress in yo-yo process to produce polarized electrons from GaAs photocathode
Authors: Li Qian  , Hao Liang  , Pang Wen-Ning  ,   清华大学物理系极化物理实验室,北京  100084
Published: December 2020

By studying the process of producing polarized electrons by the photoemission of GaAs, different experimental parameters on the generation and stability of the electron beam is discussed. A feasible way to generate stable beam of long duration is provided. There is also a discussion on producing polarized electron beam with controlled intensity.
Utilization of convex crystal spectrograph to obtain monochromatic X-ray images of Z-pinch plasmas
Authors: Ye Fan  , Xue Fei-Biao  , Guo Cun  , Li Zheng-Hong  , Yang Jian-Lun  , Xu Rong-Kun  , Zhang Fa-Qiang  , Jin Yong-Jie  ,   (1)核物理与化学研究所，绵阳  621900; (2)核物理与化学研究所，绵阳  621900；清华大学工程物理系，北京  100084; (3)清华大学工程物理系，北京  100084
Published: December 2020

The spectral resolution, spatial resolution of monochromatic X-ray images of a spectrograph based on convex crystal were discussed by ray tracing calculations taking into consideration the effect of rocking curve of the crystal. A mica convex crystal spectrograph was designed and then tested successfully on “QiangGuang-1" pulsed power facility. Time integrated monochromatic X-ray images of Al Z-pinch plasmas showed the X-ray line emissions of K-shell came from the core region of a diameter of about 2.3 mm.
Characterization of ZrN films deposited by ICP enhanced RF magnetron sputtering
Authors: Liu Feng  , Meng Yue-Dong  , Ren Zhao-Xing  , Shu Xing-Sheng  ,   中国科学院等离子体物理研究所，合肥  230031
Published: December 2020

ZrN films have been prepared by inductively coupled plasma (ICP)-enhanced RF magnetron sputtering. The effects of substrate temperature and ICP power on the microstructure and properties of ZrN films have been investigated systemically. The ZrN films show (111) preferred orientation with the substrate temperature below 300℃. ZrN(200) is observed at 450℃ regardless of ICP power, and the texture coefficient of (111) decreases. Columnar structure, which is observed in the films deposited by conventional magnetron sputtering, disappears in the film synthesized at ICP power of 200 W and substrate temperature of 300℃. With the increase of substrate temperature, N/Zr ratio and the resistivity of films decrease. The films deposited with ICP power on show denser structure, higher hardness and lower stress than those by conventional magnetron sputtering.
Study on the structural and energetic properties of two-dimensional ground state of Ag+ ion-vacancy in fast ionic conductor AgxTiS2
Authors: Song Qing-Gong  , Jiang En-Yong  ,   (1)天津大学理学院现代材料物理研究所，天津市低维功能材料物理与制备技术重点实验室，天津  300072; (2)天津大学理学院现代材料物理研究所，天津市低维功能材料物理与制备技术重点实验室，天津  300072；中国民航大学理学院材料物理系，天津  300300
Published: December 2020

Three-dimensional cell models are constructed for fast ionic conductor AgxTiS2 according to the two-dimensional ordered structure of Ag+ ion-vacancy. Geometry optimization and total energy computation are performed for ordered AgxTiS2(x=0，1/4，1/3，1/2，2/3，3/4，1)series using plane-wave pseudo-potential method based on local density approximation to density-functional theory, and the results are compared with the LixTiS2 series. The increments of lattice parameters Δa0 and Δc0 increase monotonically with increasing ion concentration, which well accords with experimental results. The total energies of AgxTiS2 and LixTiS2 system decrease linearly with increasing ion concentration, and the former decreases more rapidly. The negative formation energies of AgxTiS2(x=1/4, 1/3, 1/2, 2/3, 3/4)system indicate their ground state property, among which the formation energy of Ag1/3TiS2 system with 3{1/2}a0×3{1/2}a0 superstructure is the lowest. The formation energy of ordered AgxTiS2(x=1/4, 1/3, 1/2, 2/3, 3/4)system is lower than that of LixTiS2 system, implying higher temperature of order-disorder transition and higher activation energy of ionic diffusion. Reasonable explanation for related experimental results are presented according to these computational results.
The influence of proton irradiation on the microstructure of pure Al films
Authors: Fan Xian-Hong  , Chen Bo  , Guan Qing-Feng  ,   (1)江苏大学材料学院，镇江  212013; (2)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; (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;中国科学院研究生院，北京  100049
Published: December 2020

In this work, we investigated the microstructures of pure aluminum films irradiated with 160 keV proton by varying the irradiation dose. The vacancy clusters induced by proton irradiation in Al films are characterized by TEM, and the density and size distribution are determined. In the irradiation dose range of our studies, the density and size of vacancy clusters and the dislocation density increase with increasing irradiation dose. Our experimental results show that the dislocation density and size of vacancy clusters increase as the irradiation dose increases from 1×1011 to 4×1011/mm2. When the irradiation dose is as high as 6×1011/mm2, the number density of dislocation loops decreases, while the size of dislocation loop increases obviously. The vacancies tend to form larger clusters, accompanied by the formation of banded structures in the irradiated sample at higher irradiation doses. We found that there were small crystal orientation differences among the boundaries of banded structure. This banded structure is closely related to the degradation of mechanical and physical performance of irradiated material.
The research of detecting abrupt climate change with approximate entropy
Authors: Wang Qi-Guang  , Zhang Zeng-Ping  ,   (1)扬州大学物理科学与技术学院，扬州  225009；国家气候中心，中国气象局气候研究开放实验室，北京  100081; (2)扬州大学物理科学与技术学院，扬州  225009；中国科学院大气物理研究所东亚区域气候-环境重点实验室，北京  100029
Published: December 2020

The approximate entropy method is applied to an ideal time series. It is indicated that the method is capable of distinguishing between different structural dynamics and detecting structural dynamics mutation. And then，this method is applied to the observation data of the daily temperature and precipitation of the 740 sites between 1960 and 2000. The results showed that，the approximate entropy distribution of the temperature and precipitation has a characteristic of obvious district distribution，and displays the territorial difference of dynamic structures of climate system. Abrupt climate changes have been detected by the approximate entropy of the annual precipitation and temperature between 1970s and 1980s. The characteristics of the in homogeneity of temporal and spatial distribution of abrupt climate changes and the complexity of climate systems have been demonstrated.
Anti-synchronization of chaotic delayed neural networks
Authors: Lou Xu-Yang  , Cui Bao-Tong  ,   江南大学通信与控制工程学院，无锡  214122
Published: December 2020

By means of techniques of state observer， the anti-synchronization of a class of chaotic neural networks with time delay is investigated. Compared with the anti-synchronization strategies used in other chaotic systems， the technique presented here is rather simple and the convergence rate can be adjusted by tuning the eigenvalues through the pole placement technique. Finally， two numerical examples and computational simulations are given to show the effectiveness of the proposed scheme.
Adaptive synchronization of a class of chaotic systems with uncertain parameters
Authors: Zhang Ruo-Xun  , Tian Gang  , Li Ping  , 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

A novel adaptive synchronization method is proposed for a class of chaotic systems with uncertain parameters based on Lyapunov stability theory. Adaptive controller and updating law of parameters are obtained， and for specific error systems the controller can be simplified. This method is simple and systemic. A new chaotic system and the hyperchaotic Chen system are taken as examples to illustrate the effectiveness of the proposed method. Numerical simulation illustrates the feasibility of the technique.
Adaptive synchronization in united complex dynamical network with multi-links
Authors: Gao Yang  , Li Li-Xiang  , Peng Hai-Peng  , Yang Yi-Xian  , Zhang Xiao-Hong  ,   (1)北京邮电大学网络与交换技术国家重点实验室，北京  100876; (2)北京邮电大学网络与交换技术国家重点实验室，北京  100876；江西理工大学信息工程学院，赣州  341000
Published: December 2020

This paper further investigates the locally and globally adaptive synchronization of united complex dynamical networks based on a new method of network split. Time-delay has been introduced into networks to split and upon which a model of united complex dynamical networks with multi-links has been constructed. Several new locally and globally asymptotically stable network synchronization criteria are deduced by using Lyapunov stability theory and some hypotheses. The validity of the results was proved through numerical simulation of this paper.
The bifurcation analysis of a conjugate Chen chaotic system and the hyperchaos generation based on the system
Authors: Zhang Qing  , Wang Jie-Zhi  , Chen Zeng-Qiang  , Yuan Zhu-Zhi  ,   (1)南开大学自动化系，天津  300071; (2)中国民航大学理学院，天津  300300; (3)中国民航大学理学院，天津  300300；南开大学自动化系，天津  300071
Published: December 2020

The Hopf bifurcation is analyzed for a new type of three-dimensional autonomous chaotic system，of which the chaotic attractor belongs to the category of conjugate Chen attractors. A new four-dimensional autonomous hyperchaotic system is constructed based on this chaotic system by introducing an additional controller. This hyperchaotic system with one parameter presents hyperchaotic behavior over a range of parameter values. The analysis of Lyapunov exponents and bifurcation diagram demonstrates the evolution process from periodic orbits， quasi-periodic orbits to chaos， and further to hyperchaos as the parameter increases.
The study of a cellular automaton traffic flow model with public transit，harbor-shaped bus stop and mixed different-maximum-speed vehicles on single lane
Authors: Qian Yong-Sheng  , Wang Hai-Long  , Wang Chun-Lei  ,   兰州交通大学交通运输学院，兰州  730070
Published: December 2020

Based on the Nagel-Schreckenberg models of traffic flow， a cellular automaton traffic model with different-maximum-speed vehicles mixed on single lane is proposed， which considers public transit and harbor-shaped bus stop. The influence of deceleration probability， the density of vehicles， the average stop time of public transit vehicles， the proportion of public transit vehicles occupied in the mixed vehicles and the bus stop spacing on mixed traffic flow are analyzed by computer simulation. The models traffic flow characters are presented and analyzed.
Density-functional study of ZrnCo(n=1—13) cluster structers and their magnetism
Authors: Ren Feng-Zhu  , Wang Yuan-Xu  , Tian Fu-Yang  , Zhao Wen-Jie  , Luo You-Hua  ,   河南大学计算材料科学研究所，物理与电子学院，开封  475004
Published: December 2020

The geometries, total energies, and frequencies of ZrnCo (n=1—13) clusters have been systematically investigated by using density functional theory with the generalized gradient approximation. The equilibrium geometries, stabilities, gap and magnetism have been determined. The results show that the relative stabilities of Zr4Co, Zr7Co, Zr9Co and Zr12Co are stronger than other sized clusters, indicating that they are magic number clusters, and especially, the true ground state for Zr12Co cluster has icosahedral structure with Ih symmetry. Moreover, the stability of Zr12Co is the strongest of all the investigated clusters. The magnetic moment of ZrnCo clusters mainly comes from the localized d electron. The system magnetic moment may be divided into three stages along with the size change: n=1—3 corresponds to the stable magnetic moment, the magnetic moment of ZrnCo clusters starts to show vibration quenching from n=4, until n=8 when the magnetic moments is completely quenched. The charge transfer and the strong hybridization between s, p and d states might be one major reason for quenching of the magnetic moment of ZrnCo clusters. Meanwhile, the clusters which are composed of transition metals doped in different characteristic materials is worth further studying, for example, TMX12 and Zr13TM clusters have interestingly similar structures, stability and magnetism.
High speed reconfigurable logic gates based on single semiconductor optical amplifier
Authors: Dong Jian-Ji  , Zhang Xin-Liang  , Wang Yang  , Huang De-Xiu  ,   华中科技大学光电子科学与工程学院，武汉  430074
Published: December 2020

The nonlinearities of a semiconductor optical amplifier (SOA) are exploited to realize various all-optical signal processing at ultrahigh speed. We demonstrate reconfigurable logic gates with XNOR, AND, NOR, OR, and NOT functions based on various nonlinearities of single SOA, including four-wave mixing, cross gain modulation and transient cross phase modulation. Since the modulation speed of the SOA is limited by the recovery time of carrier density, a detuning optical bandpass filter with 0.32nm-bandwidth follows the SOA to enhance the modulation speed. Multi-logic gates at 40Gbit/s are obtained with single SOA.
Research on intense pulsed emission of screen-printed carbon nanotube cathode
Authors: Liao Qing-Liang  , Zhang Yue  , Xia Lian-Sheng  , Qi Jun-Jie  , Huang Yun-Hua  , Deng Zhan-Qiang  , Gao Zhan-Jun  , Cao Jia-Wei  ,   (1)北京科技大学材料物理与化学系，北京  100083; (2)北京科技大学材料物理与化学系，北京  100083；北京科技大学新金属材料国家重点实验室，北京  100083; (3)中国工程物理研究院流体物理研究所，绵阳  621900
Published: December 2020

A high-intensity cold cathode based on field emission from multi-walled carbon nanotubes was fabricated by screen-printing. The high intensity was obtained when the cathode was subjected to a pulsed electric field. The emission properties of the cathode were investigated in both single-pulse and double-pulse mode experiments. Emission photos of the cathode surface were investigated, and the pulsed emission mechanism of the carbon nanotube was explosive electron emission. In the single-pulse mode, the field emission current density is 99 A/cm2 at an applied electric field of 16.7 V/μm. In the double-pulse mode, the emission current density can reach 267 A/cm2 at an applied electric field of 15.4 V/μm. This carbon nanotube cathode appears to be suitable for high-power microwave device applications.
Theoretical study on the reaction mechanism of Sr,Ti,O reactions in early growth of SrTiO3 thin films
Authors: Wang Pei-Yi  , Yang Chun  , Li Lai-Cai  , Li Yan-Rong  ,   (1)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; (2)四川师范大学化学与材料科学学院，成都  610068; (3)四川师范大学计算机软件实验室，成都  610068；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; (4)四川师范大学计算机软件实验室，成都  610068；四川师范大学化学与材料科学学院，成都  610068
Published: December 2020

It is very important to learn the microscopic reaction and particle states of Sr,Ti,O atoms which are evaporated by laser molecular beam epitaxy in the early growth of SrTiO3 thin films. The preferential reaction processes of Sr,Ti,O atoms were investigated by generalized gradient approximation of density functional theory at the PW91/DNP level. The reaction mechanisms of SrO,TiO2 and SrTiO3 molecules were calculated and analyzed by highest occupied and lowest unoccupied molecular orbital theory, and several possible configurations of SrTiO3 molecules were calculated. We obtained stable configurations of SrTiO3 molecule, of which the geometric eigenvalue is similar with the SrTiO3 unit cell. These results indicate that the SrO,TiO2 and SrTiO3 molecules are the primary particle states in the early growth of SrTiO3 thin film.
First-principles study on the electronic structures of spin-Peierls compound GeCuO3
Authors: Ming Xing  , Fan Hou-Gang  , Hu Fang  , Wang Chun-Zhong  , Meng Xing  , Huang Zu-Fei  , Chen Gang  ,   (1)吉林大学材料科学与工程学院,长春  130012; (2)吉林大学材料科学与工程学院,长春  130012；吉林师范大学凝聚态物理研究所,四平  136000
Published: December 2020

The electronic structures of spin-Peierls (SP) compound GeCuO3 have been studied by first-principles calculations with plane wave pseudo-potential method. The calculated results indicate that the 3d orbital degree of freedom for the Cu2+ has been frozen, and the unpaired electrons occupy the dx2-y2 orbits. The exchange splitting of the spin-up and spin-down dx2-y2 orbitals leads to the insulating nature of the system. GeCuO3 belongs to the category of covalent insulators, since there are very strong hybridizations between the Cu 3d and O(2) 2p states around the Fermi level. These strong covalent interactions lead to not only the deviation of the ideal spin moment of the Cu2+, but also the stabilization of the one-dimensional antiferromagnetic (AFM) ordering. We fit the spin exchange coupling constants within the Noodleman's broken symmetry methods through the calculated total energy for the various spin ordered states of GeCuO3. The calculated results indicate that the one-dimensional AFM interactions along the c axis are very strong in GeCuO3, which is the essential reason that brings on the SP transition at low temperature.
Research on the current collapse in AlGaN/GaN high-electron-mobility transistors through the inverse piezoelectric polarization model
Authors: Li Ruo-Fan  , Yang Rui-Xia  , Wu Yi-Bin  , Zhang Zhi-Guo  , Xu Na-Ying  , Ma Yong-Qiang  ,   (1)河北工业大学信息工程学院，天津  300130; (2)河北工业大学信息工程学院，天津  300130；中国电子科技集团公司第十三研究所，石家庄  050051; (3)河北工业大学信息工程学院，天津  300130；中国电子科技集团公司第十三研究所，石家庄  050051；河北工程大学信息与电气工程学院，邯郸  056038; (4)中国电子科技集团公司第十三研究所，石家庄  050051
Published: December 2020

Current collapse in AlGaN/GaN high-electron-mobility transistors was studied and the effect of effective external electrical field on the concentration of two-dimensional electron gas (2DEG) near the channel of hetero-junction of AlGaN/GaN was simulated through the self-consistent implementation of the one-dimensional Poisson-Schrdinger equations. An inverse piezoelectric polarization model was proposed to analyze the degradation of 2DEG and the current collapse. It was found that the density of 2DEG was strongly dependent on the inverse polarization. When the voltage was 0,10 and 15 V, the density was 1.53×1013cm-2, 1.04×1013cm-2 and 0.789×1013cm-2, respectively. It was clear that the 2DEG density dropped 48.4% with voltage increasing from 0 to 15V when the inverse piezoelectric polarization was considered. At last, the method of restraining current collapse was further discussed.
Geometrical optimization of AlGaN/GaN field-plate high electron mobility transistor
Authors: Wei Wei  , Hao Yue  , Feng Qian  , Zhang Jin-Cheng  , Zhang Jin-Feng  ,   西安电子科技大学微电子学院，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

Results of investigation on AlGaN/GaN field-plate high electron mobility transistor with different field-plate (FP) geometry are presented. The effect of the field-plate length LFP on the electric field distribution in the channel is thoroughly analyzed by establishing a simplified model. The simulation gives the following estimates: Both the FP length LFP and the thickness t of the insulator under the FP, can reshape the electric field distribution in the channel. If LFP is short, the breakdown voltage Vbr increases with LFP. When LFP increases to a certain extent, Vbr keeps invariable. After optimizing LFP in this paper, Vbr has been increased by 64%. Good agreement between experimental and simulation data is achieved.
Magnetism and Mssbauer spectra of cyanide-bridged Ni-Fe nano-molecular-magnets
Authors: Han Wei  , Chang Shu-Quan  , Dai Yao-Dong  , Chen Da  , Huang Yan-Jun  ,   (1)南京大学物理系，南京  210093; (2)南京航空航天大学核科学与工程系，南京  210016
Published: December 2020

Nanoparticles of Prussian blue analogues Ni3［Fe(CN)6］·8.28H2O have been successfully synthesized by co-precipitation method. The nanoparticles were characterized by elemental analysis, X-ray diffraction, Fourier transform infrared spectrometry and transmission electron microscopy. Magnetic measurement was carried by superconducting quantum interference device magnetometer and the result showed the the transition temperature Tc=22.8K. The interaction between Ni(Ⅱ) and Fe(Ⅲ) was identified to be a kind of ferromagnetic coupling and was clearly explained by molecular orbital theory. The Mssbauer spectra have been used to explain the origin of magnetism.
Definition of Helmholtz and Kelvin forces in magnetic fluids
Authors: Liu Gui-Xiong  , Pu Yao-Ping  , Xu Chen  ,   华南理工大学机械工程学院，广州  510640
Published: December 2020

The Helmholtz and Kelvin forces for volume force density in magnetic fluids are valid only in some situations. Based on calculation of the volume force density in magnetic fluids, the origin for the Helmholtz and Kelvin forces in magnetic fluids is suggested, and the range of validity of them is analyzed in this paper. The calculation results show that the volume force density can be expressed in the form of Helmholtz force when the permeability of magnetic fluid is independent of the applied magnetic field, while the Kelvin force is valid when the average magnetic moment of magnetic particles in the magnetic fluid is independent of the specific volume of magnetic fluid. When the susceptibility is proportional to the density of magnetic fluid, the Helmholtz force is reduced to the Kelvin force.
The influence of anisotropic fields on stress-impedance effect in amorphous alloys
Authors: Bao Bing-Hao  , Ren Nai-Fei  , Wang Guo-Yu  ,   (1)江苏大学机械工程学院，镇江  212013; (2)江苏大学微纳米科学技术研究中心，镇江  212013; (3)江苏大学微纳米科学技术研究中心，镇江  212013；江苏大学机械工程学院，镇江  212013
Published: December 2020

The theory of stress-impedance effect in amorphous alloys was established by introducing stress-induced anisotropy and magnetic anisotropy and solving Maxwell's equations and Landau-Lifshitz equation with the Gilbert term. The established theory can be used to explain the stress-impedance effect, and the calculation results were in good agreement with the experimental results. We calculated the stress-impedance change with different anisotropy parameters, and reached important conclusions both in theory and for applications.
Coherent interactions between discrete spatial solitons in light-induced planar waveguide arrays
Authors: Xiao Fa-Jun  , Zhang Peng  , Liu Sheng  , Zhao Jian-Lin  ,   西北工业大学理学院，光信息科学与技术研究所，陕西省光信息技术重点实验室，西安  710072
Published: December 2020

The coherent interactions between one-dimensional discrete spatial optical solitons, derived by Petviashvili iteration method, are numerically investigated with the split-step beam propagation method in light-induced planar waveguide arrays. The influences of the initial phase difference, the soliton peak intensities, the periods and intensities of the writing beams for waveguide arrays, and the amplitudes of the externally bias fields on the interactions between two discrete solitons are analyzed in detail. It is found that the interactions between two parallel discrete solitons with different initial phase differences behave in a way similar to that encountered in continuous media, i.e., in-phase (out-of-phase) discrete solitons attract (repel) each other, and the intermediates are always accompanied with energy transfer. In addition, the interaction processes are influenced by the variations of soliton peak intensities, the configurations of the light-induced waveguide arrays, and the amplitudes of the external bias fields.
Femtosecond time-resolved dynamics in electron-doped high-Tc superconductor La2-xCexCuO4
Authors: Cao Ning  , Long Yong-Bing  , Zhang Zhi-Guo  , Gao Li-Juan  , Yuan Jie  , Zhao Bo-Ru  , Zhao Shi-Ping  , Yang Qian-Sheng  , Zhao Ji-Min  , Fu Pan-Ming  ,   中国科学院物理研究所北京凝聚态物理国家实验室，北京  100080
Published: December 2020

The quasiparticle dynamics in the electron-doped high-Tc superconductor La2-xCexCuO4 (LCCO) was investigated by ultrafast time-resolved optical pump-probe technique. We present results in three temperature regions: namely the low temperature (TTc) region, that around Tc(0.7Tc≤T≤Tc) and the high temperature (T>Tc) region. In general, there was a slowdown of the relaxation as the temperature decreases. However, the quasiparticle lifetime was found to exhibit a quasi-divergence as the temperature approached Tc from below. The relaxation time in normal state was much longer than what was expected for metallic relaxation, indicating the presence of a T-independent pseudogap. We have also observed picosecond rise component of photoinduced change in reflectivity ΔR/R in the electron-doped LCCO, which is attributed to the Cooper pair-breaking dynamics. The rise time became shorter as the temperature increased. The experimental results are analyzed by Rothwarf-Taylor model.
Two-step growth of highly oriented ZnO nanorod arrays
Authors: Wang Ye  , Xu Xiao-Liang  , Xie Wei-Yu  , Wang Zhuang-Bing  , Lü Liu  , Zhao Ya-Li  ,   (1)合肥工业大学物理系，合肥  230009; (2)中国科学技术大学物理系，合肥  230026; (3)中国科学技术大学中国科学院结构分析重点实验室，合肥  230026；中国科学技术大学物理系，合肥  230026
Published: December 2020

Well aligned ZnO nanorod arrays on Si substrate previously coated with a thin buffer layer of ZnO seeds via radio-frequency magnetron sputtering, which were synthesized by the aqueous solution method. The sample was characterized by scanning electron microscopy, X-ray diffraction, high-resolution transmission electron microscopy and selected area electron diffraction. The results show that ZnO nanorods have good crystal quality， are highly oriented and grown along c-axis. The full width at half maximum of the (0002) peaks of the nanorod arrays is only 0.06°. Furthermore, a strong and narrow eigen peak centered at 378nm and very weak emission in visible region due to impurities or defects were observed in the photoluminescence spectra.
The influence of atmospheric turbulence on the spatial correlation property of partially coherent Hermite-Gaussian beams
Authors: Chen Xiao-Wen  , Tang Ming-Yue  , Ji Xiao-Ling  ,   四川师范大学物理系,成都  610068
Published: December 2020

Based on the extended Huygens-Fresnel principle, the expression for the spectral degree of coherence of the partially coherent Hermite-Gaussian (H-G) beams propagating through atmospheric turbulence is derived by using the quadratic approximation of Rytov's phase structure function, and the influence of atmospheric turbulence on the spatial correlation is studied. It is shown that the oscillatory behavior and phase singularities of the degree of spectral coherence may appear when partially coherent H-G beams propagate through atmospheric turbulence, which is very different from the behavior of Gaussian-Schell-model beams. But, the oscillatory behavior becomes weaker with increasing turbulence, and even disappears when the turbulence is strong enough. The smaller the coherence parameter, the less the spatial correlation property of partially coherent H-G beams is affected by the turbulence. In addition, a comparison between the mean-squared width of the spectral degree of coherence and the mean-squared width of the spectral intensity is also given. Some interesting results are obtained, and are explained with regard to their physical nature.
The evolution of the reconstructing five-dimensional cosmological model with a big bounce
Authors: Wu Ya-Bo  , Lü Jian-Bo  , Li Song  , Yang Xiu-Yi  ,   (1)北京师范大学物理系,北京  100875; (2)大连理工大学物理与光电工程学院,大连  116024; (3)辽宁师范大学物理系,大连  116029
Published: December 2020

Based on the five-dimensional cosmological model with a big bounce, by using the forms of the effective equation of state for dark energy,the expression of the interesting function f(z) is given in this model.Furthermore,the evolution of some cosmological quantities with the redshift z is presented. In addition, it is shown that the evolution of the dimensionless density parameters Ωdm, Ωde and deceleration parameter q for the first case is the best fit one,that consists with the present observations.
Microwave processes in a RF photoinjector
Authors: Yang Zhen-Ping  , Li Zheng-Hong  ,   (1)西南科技大学理学院，绵阳  621021; (2)中国工程物理研究院应用电子学研究所，绵阳  621900
Published: December 2020

The equivalent-circuit method is adopted to study microwave processes in an RF photoinjector, and the optimized coupling between the input mcirowave system and the RF cavity is theoretically obtained based on the micro-pulse properties of the RF phtoinjector. A CAEP RF photoinjector is theoretically analyzed, and the electron beam energy spread of micro-pulses induced by beam load is also investigated.
Approximate analytic solution of a class of atmosphere-ocean coupled oscillator mechanism for globe climate
Authors: Lin Wan-Tao  , Mo Jia-Qi  ,   (1)LASG，中科院大气物理研究所,北京  100029; (2)安徽师范大学,芜湖  241000；上海高校计算科学E-研究院上海交通大学研究所，上海  200240；湖州师范学院，湖州  313000
Published: December 2020

A box model of the interhemispheric thermohaline circulation (THC) in atmosphere-ocean for globe climate is considered. By using the homotopic mapping method, a class of simplified nonlinear model is studied, and the approximate solution is obtained. The homotopic mapping is an analytic method, which gives solutions that can be analytically operated subsequently to show diversified qualitative and quantitative behaviors of corresponding physical quantities.