bluuebunny/crossref_metadata_2025 huggingface dataset:
The dynamic conversion from self-defocusing to self-focusing and the phase conjugate bright spatial soliton*
Authors: Liu Si-Min  , Wang Da-Yun  , Zhao Hong-E  , Li Zhu-Bin  , Guo Ru  , Lu Yi  , Huang Chun-Fu  , Gao Yuan-Mei  ,   (1)南开大学物理学院,天津300071; (2)南开大学物理学院,天津300071;北京师范大学物理系,北京100875; (3)天津理工大学自动化系,天津30019
Published: December 2020

We have further studied experimentally and theoretically the process of conversion from self-defocusing to self-focusing in LiNbO—3:Fe crystals, which was reported in Acta Phys.Sin.[STHZ]50[STBZ] 483. Based on our experimental result, we have proposed a new type of theoretical model of phase conjugate resonant cavity, analyzed the role of the cavity in the process of conversion from self-defocusing to selffocusing. We have also proposed a new type of bright spatial soliton, i.e.,the phase conjugate bright spatial soliton, and indicated that the bright spatial soliton is a mode in the phase conjugate resonate cavity.
Modulation on dynamical evolution of Gaussian beam in an unbiased serial photorefractive crystal circuit*
Authors: Hao Zhong-Hua  , Liu Jin-Song  ,   (1)华中科技大学激光技术国家重点实验室,武汉430074; (2)西安电子科技大学技术物理系,西安710071
Published: December 2020

Based on the theory of one\|dimensional separate spatial soliton pair formed in an unbiased serial photorefractive(PR) crystal circuit consis-ting of two PR crystals connected by electrodes, the mutual dependences of the two solitons are investigated. When a dark soliton beam and a Gaussian beam are incident on the two PR crystals, respectively, the effects of changing the peak intensity of the dark soliton on the propagating property of the Gaussian beam are discussed by numerical calculations. The result shows that the dynamical evolution of Gaussian beam in one crystal can be modulated by changing the intensity of the dark soliton in the other in the circuit. By this way one can determine whether the Gaussian beam could evolve into a solitary wave or ont.
Ｍｏｌｅｃｕｌａｒｄｙｎａｍｉｃｓｓｉｍｕｌａｔｉｏｎｓｏｆｌｏｗ ｅｎｅｒｇｙＰｔｃｌｕｓｔｅｒｄｅｐｏｓｉｔｉｏｎ
Authors: Ye Zi-Yan  , Zhang Qing-Yu  ,   大连理工大学三束材料改性国家重点实验室,大连116024
Published: December 2020

Ｍｏｌｅｃｕｌａｒｄｙｎａｍｉｃｓｓｉｍｕｌａｔｉｏｎｓｈａｖｅｂｅｅｎａｐｐｌｉｅｄｔｏｔｈｅｉｎｖｅｓｔｉｇａｔｉｏｎｏｆｔｈｅｄｅｐｏｓｉｔｉｏｎｏｆｌｏｗ ｅｎｅｒｇｙＰｔ3 8,Ｐｔ1 41 ,ａｎｄＰｔ2 6 6ｃｌｕｓｔｅｒｓｏｎＰｔ(0 0 1 )ｓｕｒｆａｃｅ .Ｔｈｅｅｖｏｌｕｔｉｏｎｐｒｏｃｅｓｓｏｆｃｌｕｓｔｅｒｄｅｐｏｓｉｔｉｏｎｗｉｔｈａｔｏｍｉｃａｖｅｒａｇｅｋｉｎｅｔｉｃｅｎｅｒｇｉｅｓ (Ｅａ)ｏｆ0 .1 ,1 .0ａｎｄ 1 0ｅＶａｎｄｔｈｅｅｆｆｅｃｔｓｏｎｔｈｅｓｕｂｓｔｒａｔｅｓｕｒｆａｃｅｍｏｒｐｈｏｌｏｇｙｈａｖｅｂｅｅｎａｎａｌｙｚｅｄ.ＳｉｍｕｌａｔｉｏｎｒｅｓｕｌｔｓｓｈｏｗｔｈａｔＥａｉｓａｎｉｍｐｏｒｔａｎｔｐａｒａｍｅｔｅｒｔｏｄｅｓｃｒｉｂｅｂｅｈａｖｉｏｕｒｓｏｆｔｈｅｃｌｕｓｔｅｓ.ＣｌｕｓｔｅｒｓｗｉｔｈｌｏｗＥａｃａｎｎｏｔｄａｍａｇｅｔｈｅｓｕｒｆａｃｅｌａｔｔｉｃｅｓｅｒｉｏｕｓｌｙａｎｄｔｈｅｃｌｕｓｔｅｒｓｃａｎｂｅｃｏｎｓｉｄｅｒｅｄａｓａｄｅｐｏｓｉｔｉｏｎｃｌｕｓｔｅｒ.ＴｈｅｐｏｗｅｒｏｆｃｌｕｓｔｅｒｄａｍａｇｉｎｇｓｕｒｆａｃｅｌａｔｔｉｃｅｉｎｃｒｅａｓｅｓｗｉｔｈｔｈｅｉｎｃｒｅａｓｅｏｆＥａ.ＷｈｅｎＥａ=1 0ｅＶ ,ｔｈｅｃｌｕｓｔｅｒｓｃａｎｉｍｐｌａｎｔｉｎｔｏｔｈｅｓｕｂｓｔｒａｔｅ.ＴｈｅｅｆｆｅｃｔｓｏｆｌｏｗｅｎｅｒｇｅｔｉｃｃｌｕｓｔｅｒｓｏｎｓｕｂｓｔｒａｔｅｓｕｒｆａｃｅｍｏｒｐｈｏｌｏｇｙａｒｅａｌｓｏｄｅｔｅｒｍｉｎｅｄｂｙＥａ.Ｔｈｅｅｆｆｅｃｔｓｏｆｃｌｕｓｔｅｒｓｗｉｔｈｍｏｒｅａｔｏｍｓ,ｈｏｗｅｖｅｒ,ａｒｅｓｔｒｏｎｇｅｒｔｈａｎｔｈａｔｗｉｔｈｆｅｗｅｒａｔｏｍｓ.Ｔｈｅｍｅｃｈａ ｎｉｓｍｓｏｆｔｈｅｉｎｔｅｒａｃｔｉｏｎｓｂｅｔｗｅｅｎｌｏｗ ｅｎｅｒｇｙｃｌｕｓｔｅｒｓａｎｄｓｕｂｓｔｒａｔｅｓｕｒｆａｃｅａｒｅａｌｓｏｄｉｓｃｕｓｓｅｄｉｎｔｈｉｓｐａｐｅｒ
Ｆｉｒｓｔ ｐｒｉｎｃｉｐｌｅｓｓｔｕｄｙｏｎα ＳｉＣ (1 0 1 0 )ｓｕｒｆａｃｅｓｔｒｕｃｔｕｒｅ
Authors: Xie Chang-Kun  , Xu Peng-Shou  , Xu Fa-Qiang  , Pan Hai-Bin  ,   (1)中国科学技术大学国家同步辐射实验室,合肥230029; (2)中国科学技术大学结构分析开放实验室,合肥230026;中国科学技术大学国家同步辐射实验室,合肥230029
Published: December 2020

Ｗｅｐｒｅｓｅｎｔａｔｈｅｏｒｅｔｉｃａｌｃａｌｃｕｌａｔｉｏｎｏｎｔｈｅａｔｏｍｉｃａｎｄｅｌｅｃｔｒｏｎｉｃｓｔｒｕｃｔｕｒｅｏｆα ＳｉＣａｎｄｉｔｓｎｏｎ ｐｏｌａｒ(1 0 1 0 )ｓｕｒｆａｃｅｕｓｉｎｇｔｈｅｆｕｌｌ ｐｏｔｅｎｔｉａｌ ｌｉｎｅａｒ ａｕｇｍｅｎｔｅｄ ｐｌａｎｅ ｗａｖｅ (ＦＰＬＡＰＷ)ａｐｐｒｏａｃｈ.Ｔｈｅｃａｌｃｕｌａｔｅｄｌａｔｔｉｃｅｃｏｎｓｔａｎｔｓａｎｄｂｕｌｋｍｏｄｕｌｕｓｏｆα ＳｉＣｃｒｙｓｔａｌａｒｅｉｎｅｘｃｅｌｌｅｎｔａｇｒｅｅｍｅｎｔｗｉｔｈｅｘｐｅｒｉｍｅｎｔａｌｄａｔａ .Ｔｈｅａｔｏｍｉｃａｎｄｅｌｅｃｔｒｏｎｉｃｓｔｒｕｃｔｕｒｅｏｆα ＳｉＣ (1 0 1 0 )ｓｕｒｆａｃｅｈａｖｅｂｅｅｎｃａｌｃｕｌａｔｅｄｂｙｅｍｐｌｏｙｉｎｇｓｌａｂａｎｄｓｕｐｅｒｃｅｌｌｍｏｄｅｌｓ.Ｉｔｉｓｆｏｕｎｄｔｈａｔｔｈｅｓｕｒｆａｃｅｉｓｃｈａｒａｃｔｅｒｉｚｅｄｂｙａｔｏｐ ｌａｙｅｒｂｏｎｄ ｌｅｎｇｔｈ ｃｏｎｔｒａｃｔｉｎｇｒｏｔａｔｉｏｎｒｅｌａｘａｔｉｏｎｉｎｗｈｉｃｈｂｏｔｈＳｉａｎｄＣａｔｏｍｓｈａｖｅｔｈｅｔｅｎｄｅｎｃｙｔｏｍｏｖｅｄｏｗｎｔｏｗａｒｄｔｈｅｂｕｌｋｔｏｆｏｒｍｐｌａｎａｒｃｏｎｆｉｇｕ ｒａｔｉｏｎｗｉｔｈｔｈｅｉｒｎｅｉｇｈｂｏｕｒｓａｎｄＳｉｍｏｖｅｓｆｕｒｔｈｅｒｔｏｗａｒｄｔｈｅｂｕｌｋｔｈａｎＣｄｏｅｓ.Ｆｕｒｔｈｅｒｍｏｒｅ ,ｓｕｒｆａｃｅｒｅｌａｘａｔｉｏｎｉｎｄｕｃｅｓｔｈｅｔｒａｎｓｆｏｒｍａｔｉｏｎｆｒｏｍｓｅｍｉ ｍｅｔａｌｌｉｃｔｏｓｅｍｉｃｏｎｄｕｃｔｉｎｇｃｈａｒａｃｔｅｒｉｚａｔｉｏn
Influence of entanglement degree on squeezing and photon antibunching in the tw o-photon Jaynes-Cummings model
Authors: Zhang Guo-Feng  , Jia Xin-Juan  , Yan Qi-Wei  , Liang Jiu-Qing  ,   (1)山西大学理论物理研究所，太原  030006; (2)山西大学理论物理研究所，太原  030006;中国科学院物理研究所与凝聚态物理中心磁学国家重点实验室，北京  100080; (3)中国科学院物理研究所与凝聚态物理中心磁学国家重点实验室，北京  100080
Published: December 2020

We mainly consider the case that one of the two entangled atoms with two energy levels interacts with a single-mode and double-photon cavity field. The atom is selectively detected after exiting the cavity, and it is found that the noncla ssical properties of field states depend strongly on the entanglement degree bet ween the two atoms. Meanwhile, it is proved that the squeezing of the field and the photon antibunching can be greatly enhanced via selective atomic measurement s.
Spectroscopic derivative in optical study of GaInAs/InP and GaInP/AlGaInP multip le quantum wells
Authors: Shao Jun  ,   Physikalisches Institut,Universitt Stuttgart,D-70550 Stuttgart,Germany;中国科学院上海技术物理研究所红外物理国家重点实验室，上海  200083
Published: December 2020

With a brief discussion of the physical mechanism of spectroscopic derivative, the successful applications are given in optical absorption and reflectivity study of GaxIn1-xAs/InP and GaxIn1-xP/Al GaInP multiple quantum wells . The effects of different orders of the derivative are compared with each other , and the difference is pointed out between this method and the curve-fitting me thod as well as the double modulation method. A conclusion is reached that the m ethod is practical and reliable in the optical study of wide band-gap quantum we lls.
A new method to evaluate reliability in GaAs PHEMT's
Authors: Liu Hong-Xia  , Zheng Xue-Feng  , Han Xiao-Liang  , Hao Yue  , Z hang Mian  ,   (1)西安电子科技大学微电子研究所，西安  710071; (2)信息产业部十三所，石家庄  050002
Published: December 2020

This paper analyzes the degradation in GaAs pseudomorphic high electron mobitity transistors (PHEMT's) by measuring the electric characteristics in GaAs PHEMT's before and after stress. The relation between impact ionization rate and maximu m channel electric field is gained. An analytical expression of impact ionizatio n rate versus maximum channel electric field is deduced by fitting the experimen tal results. The electric characteristic and reliability in GaAs PHEMT's can be improved and evaluated using the analytical expression. The impact ionization in channel should be decreased in order to improve the breakdown voltage in GaAs P HEMT's.
The study of charge fluctuations in superconductors characteristics
Authors: Liang Fang-Ying  , Qing Xin  , Zhong Yu-Rong  , Ding Shuang-Hong  ,   烟台大学光电信息科学与技术学院，烟台  264005
Published: December 2020

We used the first equation of Ginzburg_Landau theory to study superconductivity with no magnetic field considered. We have obtained the effective mass m of Ginz burg_Landau equations, which has a special property, namely it can be negative. Some explicit expressions for different cases are derived, which are consistent with experimental data.
A study on magnetic and magneto-optical properties of PdMn/Co multilayers
Authors: Zhou Xun  , Liang　Bing-Qing  , Wang Hai  , Zhang Zhen-Rong  , Chen Liang-Yao  , Wang Yin-Jun  ,   (1)复旦大学物理系，上海  200433; (2)中国科学院物理研究所磁学国家重点实验室, 北京  100080; (3)中国科学院物理研究所磁学国家重点实验室, 北京  100080;贵州师范大学物理与电子科学系，贵阳  550001
Published: December 2020

Co/Pd1-xMnx multilayers with Mn concentration x=0 to 20.8 % have been sp uttered on a glass substrate with 40 nm thick Pd or PdMn buffer. With the combin ation of small_ and large_angle x_ray analyes, the crystal structure of the samp les were investigated. Hysteresis loop and perpendicular magnetic anisotropy (PM A) were measured by means of an alternating_gradient magnetometer and magnetic t orque. Domain structure was observed by magnetic force microscopy. Saturation ma gnetization, PMA and the Kerr rotation spectrum of the samples were investigated . It is shown that the change of Kerr rotation with the increase of Mn concentr ation in Pd could be ascribed to the variation of diagonal and off_diagonal elem ents of the dielectric tensor.
Study on the magnetic anisotropy of the (Fe1-xCox)84Zr3.5Nb 3.5B8Cu1 nano-crystallite ribbon with the metho d of magnetic resonance
Authors: Hou Bi-Hui  , Liu Feng-Yan  , Guo Hui-Qun  ,   (1)北京工业大学应用数理学院,北京  100022; (2)中国科学院物理研究所磁学国家重点实验室,北京  100080
Published: December 2020

We have carried out an experimental study based upon the ferromagnetic resonance (FMR) on the anisotropy of alloy ribbons of (Fe1-xCox)84Zr3.5Nb3.5B8Cu1(x=0.0, 0.2, 0.4, 0.6, 0.8). The easy axes of the samples are in the lateral direction of the ribbons, While the single-axis anisotropy c onstant K′ of the samples having the same width decreases as the amount of Co i ncreases. The value of K′ lies between 4.67×10-5J/m4(x=0 .0) and 2.54× 10-5J/m4(x=0.8). Since the imaginary part χ″ of the alte rnating curren t magnetic susceptibility changes nonlinearly with the magnetic field H, there is a low field (0—12　mT) non_resonance signal having a comparable strength wit h that of the ferromagnetic resonance signal. It is found through the study on t he magnetic process of the alloy ribbon of Fe84Zr3.5Nb3.5B8C u1 that dχ″/dH=0 in the regions of the reversible (0—12　mT)　and saturated (9.0 mT—12 mT) magnetization that χ″(H) is related to the n_th power of H, i .e., Hn(n≥3) when the domain wall motion is nonreversible; and χ″ is relate d to H2 during the domain rotation (Rayleigh region, dχ″dH is a con stant). S pecifically, it is found that the χ″(H) proportional to H2 and tha t proportional to Hn(n≥3) appear alternatively in three sections, correspon ding to the disappearance of different domains.
The forced solution mechanism of alloying agents of 7075 alloy as-cast ingot und er the effects of electromagnetic field
Authors: Zhang Qin  , Ban Chun-Yan  , Cui Jian-Zhong  , Ba Qi-Xian  , Lu Gui-Min  , Zhang Bei-Jiang  ,   材料电磁过程教育部重点实验室，东北大学,沈阳  110006
Published: December 2020

The influence of electromagnetic field with a low frequency on the microstructure and solute solubility of 7075 alloy produced by CREM process have been investigated. Evolution of the liquidus and solidus as well as the solidification interval are also measured. Meanwhile, the flow pattern and temperature field before and after the application of electromagnetic field is also given by numerical simulation. The forced solution mechanism of alloying agents of 7075 alloy under the effects of electromagnetic field is explained from such factors as solute equilibrium coefficient of distribution, solidification interval, flow pattern and temperature field in sump and microstructure.
Perturbation to the symmetries of relativistic Birkhoffian systems and the inver se problems
Authors: Fu Jing-Li  , Chen Li-Qun  , Xie Feng-Ping  ,   (1)商丘师范学院数学力学和数学物理研究所,商丘  476000; (2)商丘师范学院数学力学和数学物理研究所,商丘  476000;上海大学上海市应用数学和力学研究所,上海  200072; (3)上海大学上海市应用数学和力学研究所,上海  200072
Published: December 2020

In this paper, we have studied the positive problems of perturbation to the symmetries for relativistic Birkhoffian systems under the action of a small force of the disturbance. The fundamental theory, equations of motion and equation of small disturbance of relativistic Birkhoffian systems were established. Lie symmetries and conserved quantity of this systems were given. Perturbation to the symmetries of the systems under infinitesimal transformations, s-order adiabatic invariants, existence conditions and the form of adiabatic invariants were studied. We have also studied the inverse problems of perturbation to the symmetries for relativistic Birkhoffian systems. We obtain the perturbation to the symmetries of the systems under infinitesimal transformations, when the systems possess s-order adiabatic invariants. The relationship between relativistic Birkhoffian systems and classical Birkhoffian systems were studied. Finally an example was presented to illustrate the result.
Genetic-based neural network control for chaotic system
Authors: Wang Yao-Nan  , Tan Wen  ,   (1)湖南大学电气与信息工程学院，长沙  410082; (2)湖南大学电气与信息工程学院，长沙  410082;湖南科技大学信息与电气工程学院，湘潭  411201
Published: December 2020

A novel genetic-based neural network control for chaos is presented. The method proposed has been successfully applied to control two simulated chaotic systems by incorporating the techniques of small perturbations and the periodic control in this paper. The simulation results showed that the neural network trained by genetic algorithm can learn to produce a series of small perturbations to conver t chaotic oscillations of a chaotic system into desired regular ones. The scheme requires no knowledge about the mathematical model. Moreover, the approach is r easonably robust to noise, it can be extended to control other chaotic systems.
The energy density in a one-dimensional cavity with two moving boundaries
Authors: Li Ling  , Li Bo-Zang  ,   (1)四川师范大学物理系，成都  610066;四川大学物理科学与技术学院，成都  610065; (2)中国科学院物理研究所与凝聚态物理中心，北京  100080
Published: December 2020

Based on the numerical solutions of the generalized Moore's equations, the energy density is studied for the one-dimensional cavity where two boundaries oscillate resonantly. The feature of energy density depends strongly on the frequency, amplitude and dephasing of resonant motions of the boundaries. In some special cases, the packet structure takes place in the energy density.
Photonic logic gates based on bacteriorhodopsin
Authors: Feng Xiao-Qiang  , Hou Xun  , Yang Wen-Zheng  , Yang Qing  , Chen Feng  ,   (1)中国科学院西安光学精密机械研究所瞬态光学技术国家重点实验室，西安  710068; (2)中国科学院西安光学精密机械研究所瞬态光学技术国家重点实验室，西安  710068;西安交通大学电子科学与技术系，西安  710049; (3)中国科学院西安光学精密机械研究所瞬态光学技术国家重点实验室，西安  710068;中国科学院研究生院，北京  100039
Published: December 2020

In this letter three photonic logic gate models are presented based on the bacteriorhodopsin(BR) polymer made from variant D96N. With the illumination of 633nm laser the BR molecules can be excited to the M state and show a strong absorption at 412nm, so the intensity of transmitted purple light will decrease until zer o when the exciting light is strong enough. A CCD camera is used to detect t he distribution of transmitted purple light intensity that can be modulated by i llumination of 633nm laser on BR film and NOT, ORNOT, ANDNOT gates are simulated under the special intensity of purple light.
Propagation of ultrashort THz pulse in random scattering media
Authors: Chen Min  , Xiao Ti-Qiao  , Xu Hong-Jie  ,   中国科学院上海原子核研究所，上海  201800
Published: December 2020

Propagation of a femtosecond THz pulse in random scattering media is described using Monte-Carlo simulation. We study the effects of the radius of scattering spheres and the depth of scattering media, in relation to the parameters of scatt ering coefficient and anisotropic factor by Mie theory. The results show that wh en Mie theory holds, the smaller the spheres, the more the THz pulse is scattere d. The scattering effect expands in the width of pulse in temporal domain and re duces the imaging resolution of THz pulse in random scattering media.
The effect of rapid quenching from melt on Martensitic transition and strain cha racteristics of Ni-Mn-Ga alloy
Authors: Li Jian-Liang  , Zhao Wei-Ren  , Zhang Yang-Huan  , Wang Xin-Lin  , Zhang Jian-Fu  , Guo Shi-Hai  ,   (1)钢铁研究总院功能材料研究所，北京  100081; (2)汕头大学理学院物理系,汕头  515063
Published: December 2020

Ni50Mn27Ga23/sub> alloy was prepared by melt_spinning at wheel velocities of 2,4 and 8m/s separately. The experimental results showed that the rapid quenching caused the decrease of the martensitic transformation temperature an d Curie temperature, while subsequent annealing would increase the depressed val ues. The NiMnGa specimens with a single_phase structure could be obtained more e asily in melt_spun ribbons than in cast alloys. Furthermore, x_ray diffraction s tudies revealed that the main diffraction peak drifted from (220) to (400) in me lt_spun ribbons, which made the texture form, and subsequent annealing made it d isappear. The effects of rapid quenching on the phase_transition strain and magn etic field_induced strain are very complicated. It was found that the phase tran sition strain and magnetic field_induced strain of melt_spun ribbons with textur e were larger than that of cast specimens.
Investigation on the oxygen contamination in the μc-Si∶H thin film deposited b y VHF-PECVD
Authors: Yang Hui-Dong  , Wu Chun-Ｙa  , Zhao Ying  , Xue Jun-Ｍing  , Geng Xin-Ｈua  , Xiong Shao-Ｚhen  ,   (1)南开大学光电子研究所,天津  300071; (2)南开大学光电子研究所,天津  300071;五邑大学薄膜与纳米材料研究所,江门  529020;东华大学理学院,上海  200051
Published: December 2020

Investigations on the oxygen contamination in the μc_Si∶H thin films deposited by very_high_frequency plasma_enhanced chemical_vapor deposition(VHF_PECVD) technique with and without load lock chamber have been reported in this paper. From the results of x_ray photoelectron spectroscopy and Fourier transform infrared absorption measurements, it can be identified that oxygen exists in μc_Si∶H film with different bonding modes, namely Si—O bonding, O—H bonding and O—O b onding. In addition, the influences of oxygen on the structural and electrical p roperties of the films are studied with Raman spectra, conductivity(σ) and acti vation energy (Ea) measurements. The results reveal that structural propertie s of the μc_Si∶H film depend strongly on the bonding modes of the existing oxy gen. The electrical properties show that the role of oxygen in μc_Si∶H films i s different from those in a_Si∶H and the essential mechanism needs to be furthe r explored.
Investigation of the fabrication and structure of double-wall carbon nanotubes
Authors: Wang Miao  , Li Zhen-Hua  , Saito Yahachi  ,   (1)日本三重大学工学部，津  514-8507; (2)浙江大学力学系，杭州  310027; (3)浙江大学物理系，杭州  310027
Published: December 2020

Using the composite graphite rods with the sulphide of iron group metals as anode, the double-wall carbon nanotubes have been fabricated by arc discharging under hydrogen atmosphere. By means of transmission electron microscope, it was found that the double-wall carbon nanotubes were formed in the inner-walls of the evaporation chamber and around the cathode.
Bound states of Klein-Gordon equation for scalar and vector linear potentials
Authors: Chen  Gang  , Zhao Ding-Feng  ,   (1)南京陆军指挥学院，南京  210045; (2)绍兴文理学院物理系，绍兴  312000
Published: December 2020

The s-wave bound state solutions of Klein-Gordon equation are obtained when a linear-type scalar potential is not less than its vector potential, and its solutions are expressed by the confluent hypergeometric function.
Using pulse voltage differential feedback method to control chaos in the buck co nverter
Authors: Zou Yan-Li  , Luo Xiao-Shu  , Fang Jin-Qing  , Wang Bing-Hong  ,   (1)广西师范大学物理与电子科学系，桂林  541004; (2)中国科学技术大学近代物理系，合肥  230026; (3)中国原子能科学研究院，北京  102413
Published: December 2020

We analyze the mechanism of generating chaos in the buck converter through three kinds of typical switching logical diagrams, point out that when the switch S i s on, the capacity charges too fast.This is the main reason why chaos is generat ed in the circuit. Then based on the above analysis, we present the method of us ing output voltage pulse differential feedback to control chaos in the buck conv erter. Theoretical analysis, numerical calculation and circuit simulation demons trate the validity of this chaos control method.
AlGaN/GaN heterojunction wavefunction half analytic model based on quantum distu rbance
Authors: Li Pei-Xian  , Hao Yue  , Fan Long  , Zhang Jin-Cheng  , Zhang Jin-Feng  , Zhang Xiao-Ju  ,   西安电子科技大学微电子研究所，西安  710071
Published: December 2020

Based on the quantum disturbance theory,a half-analytic model was achieved that can be used in the calculation of the eigen function and eigen energy of the two-dimensional clectron gas in a AlGaN/GaN heterojunction.The theoretical analysis and calculation result of the model were given.The calculation result was compared with that of the difference method.The method in this paper is superior to the difference method when solving a large-scale problem because of its convergence and efficiency and is well fitted for the calculation of the quantum well problem in the AlGaN/GaN heterostructure.
Study of hyperchaotic behavior in quantum cellular neural networks
Authors: Cai Li  , Ma Xi-Kui  , Wang Sen  ,   (1)空军工程大学工程学院，西安  710038; (2)西安交通大学电气工程学院，西安  710049; (3)西安交通大学电气工程学院，西安  710049;空军工程大学工程学院，西安  710038
Published: December 2020

The nonlinear dynamical behavior of a quantum cellular neural network (QCNN) by coupling quantum-dot cellular automata was investigated. The theoretical analysis and simulation for a three-cell coupled QCNN has been done by using the polarization of a quantum-dot cell and the quantum phase as state variables. The com plex and abundant chaotic behaviors can be observed. Chaotic oscillations occur very easily. Two positive maximum Lyapunov exponents have been calculated in ord er to verify the hyperchaotic behavior.
Globalized numerical modeling of electromagnetic scattering from conductive targ ets with open cavity and electrically large size
Authors: Nie Zai-Ping  , Wang Hao-Gang  ,   电子科技大学微波工程系，成都  610054
Published: December 2020

In this paper, the electromagnetic scattering from conductive target with open cavity has been simplified as two (inner and outer) equivalent models by using the equivalence principle and introducing an equivalent magnetic current in the aperture of the cavity. For the inner part of the cavity, the equivalent conductance matrix has been obtained by use of connection scheme. Approximate boundary in tegral method has been used to describe the coupling between inner and outer pa rts of the cavity, and to obtain the aperture equivalent magnetic current. Final ly, the general combined field integral equation was presented to form the elec tromagnetic model of the scattering problem, and the multilevel fast multipole a lgorithm was used to solve this problem efficiently. Numerical examples show go od agreement between calculated results and measured data.
Temperature field and formation of crater on the surface induced by high curren t pulsed electron beam bombardment
Authors: Qin Ying  , Wang Xiao-Gang  , Dong Chuang  , Hao Sheng-Zhi  , Liu Yue  , Zou Jian-Xin  , Wu Ai-Min  , Guan Qing-Feng  ,   (1)大连理工大学三束材料改性国家重点实验室，物理系，大连  116024; (2)吉林大学材料科学与工程学院，长春  130025
Published: December 2020

The present paper aims at revealing the formation mechanism of craters on the surface of metals produced by the bombardment of a high-current pulsed electron beam. Based on experimental investigations and a physical model, the temperature field and melting process are simulated for Al and two kinds of steels. The star ting melting positions, largest crater depths, and melting layer thicknesses are obtained, which agree satisfactorily with experimentally observed values. It is confirmed that temperature rises faster at a sublayer instead of on the extreme surface due to the maximum energy deposition located at about 1/3 of the total penetration depth of the beam. Such a special sublayer heating and melting mode causes eruptions of the sublayer liquid through the outer surface and produces t he typical surface crater morphology.
Generalized Tschebyshev polynomial and its application in solving the strong cou pling waveguide equations
Authors: Guo Qi-Zhi  , Tan Wei-Han  , Meng Yi-Chao  ,   (1)上海大学光纤研究所,上海  201800; (2)上海大学物理系,上海  200436
Published: December 2020

In this paper, by means of generalized Tschebyshev polynomial, the analytical so lution is derived for (N+1)×（N+1） waveguide couplers arranged in a ring with strong coupling. As a concrete example, the solution of 5×5 waveguide couplers is calculated, and the relationship between strong and weak couplings is analyze d. The property of generalized Tschebyshev polynomial is discussed in detail.
Study on the relationship of average ionization stage with the electron temperat ure for Au laser produced plasma
Authors: Zhang Hong  , Cheng Xin-Lu  , Yang Xiang-Dong  , Xie Fang-Jun  , Zhang Ji-Yan  , Yang Guo-Hong  ,   (1)四川大学计算机学院，成都  610065; (2)四川大学物理科学与技术学院，成都  610065; (3)中国工程物理研究院激光聚变研究中心，绵阳  621900
Published: December 2020

A collisional radiative model based on the spin-orbit-split-arrays was developed and used to determine the charge state distributions. The atomic structure code of Cowan and the spin-orbit-split-arrays model is used to calculate all the emission spectra of the different gold species, and a non-local thermodynamic eguilibrium model is coupled to calculate the ion populations and the charge state distributions at a given density and temperature. The relationship between average charge state and the electron temperature is given.In general, the avera ge charge state increases with electron temperature, except between 3800 and 390 0 eV. The reason for this unusual region is that the ionization potential increa ses much sharply between Au51 and Au52.
Buckling behavior of carbon nanotube under compression
Authors: Wang Yu  , Wang Xiu-Xi  , Ni Xiang-Gui  , Wu Heng-An  ,   中国科学技术大学力学和机械工程系，合肥  230026;中国科学院材料力学行为和设计重点实验室，合肥  230026
Published: December 2020

The buckling behavior of carbon nanotubes(CNTs) under compression is simulated, by using the Tersoff-Brenner potential to describe the interactions in CNTs. The results show that Young modulus of CNTs decreases as the radii of CNTs increase. The Young modulus of zigzag CNT is higher than that of armchair CNT. The micro characteristic of the nanotube buckling is explained from the viewpoints of energy and structure distortion.
Large magnetoresistance in Cox-C1-x granular films on Si(1 00) substrate prepared by pulsed laser deposition
Authors: Zhu Dan-Dan  , Zhang Xiao-Zhong  , Xue Qing-Zhong  ,   清华大学材料科学与工程系,北京  100084
Published: December 2020

A large positive magnetoresistance (MR) has been observed in Cox-C1-x gr anular films prepared on Si(100) substrates by pulsed laser deposition (PLD). Co 0.02-C0.98 sample has the largest room-temperature MR of 2 2% at the magnetic field B=1T. It is noted that in the Cox-C1-x/Si s tructure, the MR at room-temperature is much larger than that at low temperatures. The room-te mperature positive MR of the Cox-C1-x films has a B2/ 3 dependence when B＜1T and a B1/2 dependence when B＞1T. Such magnetotransport pr opert ies have never been reported before. It appears that some new mechanisms play im portant roles in the magnetotransport of the Cox-C1-x film s. Further stu dy on the MR mechanism of the Cox-C1-x/Si structure will n ot only shed l ight on the study of spin electronics and magnetism, but also make possible the application of the Cox-C1-x/Si in information industry.
Effect of boundary on the two-dimensional inclined channel for a dilute granular flow distribution
Authors: Zhou Ying  , Bao De-Song  , Zhang Xun-Sheng  , Lei Zhe-Min  , Hu Guo-Qi  , Tang Xiao-Wei  ,   浙江大学物理系,杭州 310027
Published: December 2020

We have investigated experimentally the twodimensional flow of stainless steel balls through a smooth inclined plane and between two parallel plates so that the side walls are rough and the inclination is adjustable. It is shown that th e dynamical behavior of the dilute granular flow is different from the Newtonian fluids because of the energy dissipation. Compared to the viscous fluids, the velocity profiles of the granular flow are more blunted than the parabolic form and the density profiles are nonuniform. Near the side walls, the density is hig her than the center of the channel. The distribution of the density is influence d by increasing inclination and the width of the channel. The transverse d istribution of the granules in the channel is affected chiefly by the density di stribution.
Lifetime of the plasma channel produced by ultra-short and ultra-high power laser pulse in the air
Authors: Lu Xin  , Xi Ting-Ting  , Li Ying-Jun  , Zhang Jie  ,   (1)中国科学院物理研究所光物理实验室,北京 100080; (2)中国矿业大学物理系，北京 100083
Published: December 2020

The time evolution of plasma channel produced by ultrashort and ultra high power laser pulses in the air has been investigated. The theoretical model considers the recombinati on of free electrons, positive and negative ions, as well as the attachment and detachment of electrons on neutral molecules in the air under the interaction with the successive coming laser's pulses. The analytical solution of rate equations of the charged particles in the plasma channel has been found when the detachment laser intensity is constant. Calculations show that the lifetime of the plasma channel with an electron density higher than 1012—1013cm-3 can be extended to microseconds by using a detachment laser to suppress the attachment between el ectrons and neutral moleculars. In the case of same wavelength and average power, the detachment efficiency of a short pulse sequence with a high repetiti on rate is higher than that of a continuous detachment laser.
Experimental investigation of supersonic x-ray transport in radiatively heated CH foam cylinders on ShenguangⅡ facilities
Authors: Jiang Shao-En  , Sun Ke-Xi  , Zheng Zhi-Jian  , Ding Yong-Kun  , Yang Jia-Min  , Miao Wen-Yong  , Cui Yan-Li  , Chen Jiu-Sen  , Yu Yan-Ning  ,   中国工程物理研究院激光聚变研究中心，绵阳 621900
Published: December 2020

Supersonic radiation transport, where the ratio of the radiation wave front velocity to the material sound speed was more than 10, has been investigated experimentally in the low-density foam. Four beams of 0.35μm laser with pulse d uration of 1ns and 2kJ of total energy entered into a hohlraum to create intense x-ray radiation that heated C66H12</sub aerogel of foams of varying length a nd density on the Shenguang Ⅱ laser facility. The soft x-ray spectrometers (Dante) prov i ded the time delay and the velocity of the x-ray radiation propagation at three ener gies of 80, 250 and 400eV. The x-ray spectra and radiation temperature resolved temporally were simultaneously obtained with Dante. An x-ray streaked camera vie wing the face on at the energy of 700eV provided clean signatures of the radiat i on breakout from the rear of the foam sample and plasma filling in the cylindric al hohlraum. The model of `leakage pipe' on radiation transport was used to anal yze the experimental results, and the data and model were basically consistent.
Explosion of cathode plasma in intense multi-beams electron vacuum diode
Authors: Xia Lian-Sheng  , Wang Meng  , Huang Zi-Ping  , Zhang Kai-Zhi  , Shi Jin-Shui  , Zhang Lin-Wen  , Deng Jian-Jun  ,   中国工程物理研究院流体物理研究所，绵阳 621900
Published: December 2020

This paper is involved in generation, explosion of cathode plasma of electron va cuum diode under four-pulse mode. Diode breakdown caused by cathode explosion is observed in experiment. On the assumption that the diode beams are space charge limited beams and according to the experimental data, the explosion velocity of cat hode plasma is 0.5—4cm/μs and is different from each other in differe nt pulse process. The effects of explosion of cathode plasma on diode voltage, dio de impendence and multi-pulse beams are analyzed too.
Effect of pulsed magnetic field on the Fe-based amorphous alloys
Authors: Chao Yue-Sheng  , Li Ming-Yang  , Geng Yan  , Liu Ji-Gang  ,   东北大学理学院，沈阳 110004
Published: December 2020

Amorphous Fe78 Si9 B13alloys have been treated by pulsed magnetic field with lowe r frequency. The macrostructural change of amorphous specimens after treatment were observed by mssbauer spectroscopy and TEM etc.This investigation show that nanocrystallization of amorpous Fe78 Si9 B13occurs under the con ditions: pulsed fiel d 16—32kA/m,pulse frequency 20—25 Hz,acting time ≤2min. The grain size of nano crystalline phase Fe(Si) is about 10nm. And, the temperature rise of specimens during the course of the application of pulsed magnetic field is very low(ΔΤ≤20℃).
A study on the resistance minima in an amorphous alloy at low temperature
Authors: Huang Zhi  , Bai Hai-Yang  , Jing Xiu-Nian  , Wang Zhi-Xin  , Wang Wan-Lu  ,   (1)中国科学院物理研究所，北京 100080; (2)重庆大学应用物理系，重庆 400044; (3)重庆大学应用物理系，重庆 400044;中国科学院物理研究所，北京 100080
Published: December 2020

In this paper, we study the electrical resistance of nonmagnetic amorphous alloy Cu60Zr20Hf10Ti10 and amorphous ferromagnet Fe61Co7Zr10Mo5W2B15. We fit the c urve in the light of special models, and analyze the origination of the minima which occurs in both of the samples. The contributions both from the disorder structure and magnetic status are discussed.
Study on the humidity sensitive behavior of multiwalled carbon nanotubes
Authors: Wu Zi-Hua  , Wang Wan-Lu  , Liao Ke-Jun  , Wang Yong-Tian  , Hu Chen-Guo  , Fu Guang-Zong  , Wan Bu-Yong  , Yu Peng  ,   重庆大学数理学院应用物理系，重庆 400044
Published: December 2020

The humidity sensitive properties of multiwalled carbon nanotubes(MWNTs) films h ave been studied.Multiwalled carbon nanotubes were synthesized by hot filament chemical vapor deposition.Carboxyl modified and non_modified MWNTs film's tempera ture effect and humidity sensitive behavior were investigated separately.The res ults showed that carboxyl modified MWNTs films were very sensitive to temperatur e and humidity,response and restored time were much faster than that of non_modi fied MWNTs films.The origin of humidity sensitivity of MWNTs films were also discussed,and the theoretical formula was given.
Spin dynamics in doped spatially anisotropic triangular antiferromagnets
Authors: Liu Bin  , Liang Ying  , Feng Shi-Ping  ,   (1)北京师范大学物理系,北京 100875; (2)北京师范大学物理系,北京 100875;中国科学院交叉学科理论研究中心,北京 100080
Published: December 2020

Within the t_J model, the spin dynamics of the underdoped spatially ani sotropic triangular antiferromagnets is studied based on the fermion_spin theory . It is shown that the pattern of the neutron scattering peaks depends on both a nisotropic parameter and doping. Although the positions of the neutron scatterin g peaks are energy independent, the weight of these peaks decreases with increas ing energy.
Investigation of open RF cavity by coupling theory
Authors: Li Zheng-Hong  , Meng Fan-Bao  , Chang An-Bi  , Hu Ke-Song  ,   中国工程物理研究院应用电子学研究所,绵阳　621900
Published: December 2020

In the paper, an open cavity is divided into two parts: closed part and open part. The closed part means the closed cavity, and the open part is equi valent to the absorbing traveling boundary. According to Maxwell theory, there exists a coupling equation between the modes of the closed cavity and those of the open part.Utilizing the method, the X-band six-cavity transit time oscill
ator is calculated; the calculated frequency and the Q value of the working mode are very close to the measured values.
The variable separation approach and study on solving the variable-coefficient nonlinear Schr?dinger equation
Authors: Zhang Jie-Fang  , Xu Chang-Zhi  , He Bao-Gang  ,   (1)浙江师范大学非线性物理研究所,金华　321004; (2)浙江师范大学非线性物理研究所,金华　321004；金华教育学院物理系,金华　321000
Published: December 2020

In this paper, a variable separation approach is proposed and successfully extended to the (1+1)dimensional physics models. The new exact solution of two classes of variable-coefficient nonlinear Schrdinger equations are obtained. As a specific example, the envelope soliton solution for nonlinear Schr?dinger equations are a by-product, which is somewhat different in form, from the present result.
Phase probability distributions of Roy-type even and odd nonlinear coherent states
Authors: Wang Ji-Suo  , Liu Tang-Kun  , Feng Jian  , Sun Jin -Zuo  ,   (1)聊城大学物理系，聊城  252059; (2)聊城大学物理系，聊城  252059;烟台大学物理系，烟台  264005;中国科学院武汉物理与数学研究所波谱与原子分子物理国家重点实验室，武 汉  430071; (3)烟台大学物理系，烟台  264005; (4)中国科学院武汉物理与数学研究所波谱与原子分子物理国家重点实验室，武 汉  430071;湖北师范学院物理系，黄石  435002
Published: December 2020

Based on our previous work, with the aid of the numerical method, the phase pro bability distributions of Roy-type even and odd nonlinear coherent states are in vestigated. It is shown that the distributions for the states are rather different, and unlike the case of ordinary even and odd coherent states the Pegg-Barnett distribution clearly reflects the different characters of quantum interference in the case of Roy-type even and odd nonlinear coherent states.
Comparative studies on annealed proton exchange waveguides inY-cut MgO:LiNbO.3 and Z-cut LiNbO.3
Authors: Cao Xia  , Wang Zhi-Ｇuo  , He Sai-Ｌing  , Xia Yu-Ｘing   , Zhan Li  ,   (1)上海交通大学应用物理系，上海　200030; (2)同济大学物理系，上海　200092; (3)浙江大学现代光学仪器国家重点实验室光与电磁波研究中心，杭州　31002 7
Published: December 2020

Proton exchange waveguides in MgO:LiNbO.3 and LiNbO.3 crystals were fabricated , and the diffusion coefficients for the proton exchange process are obtained. The evolution characteristics of the waveguide index profile in the annealing process are studied. The structural deformation of the proton exchange waveguides in Mg O:LiNbO.3 and LiNbO.3 and the restoration effect of annealing are also studied tho roughly by the x-ray diffraction method and the OH-infrared absorption method. The optical and structural characteristics of annealed proton exchange waveguides in MgO:LiNbO.3 and LiNbO.3 are analysed and compared with eath other.
First-principles investigation of charge disproportionation in HoNiO＿3 perovskite
Authors: Meng Xing  , Xu Xiao-Guang  , Liu Wei  , Sun Yuan  , Chen Gang  ,   吉林大学汽车材料教育部重点实验室，材料科学与工程学院，长春　130012
Published: December 2020

We have investigated the electronic structure of HoNiO_3 perovskit e using first principles based on the density_functional theory. A comparison of elec tron_density map between orthorhombic and monoclinic structures indicated that there is only one type of Ni^3+state in the orthorhombic_metallic phase (space group Pbnm), and there are two types of Ni^(3-δ)+ and Ni^(3+δ) + states in the monoclinic_insulating phase ( space group P2_1/n). The characteristic parameter of charge di sproportionation δis concerned with the non_bonding t_2g band of partial density of states of Ni3d electron. δis calculated to be 0. 34±0.01， based on the changes of t_2gband from orthorhombic to monoclinic phase.
Study on the measure synchronization in coupled Hamiltonian systems*
Authors: Chen Shao－Ying  , Xu Hai－Bo  , Wang Guang－Rui  , Chen Shi－Ga ng  ,   (1)北京应用物理与计算数学研究所，北京\ 100088; (2)中国工程物理研究院北京研究生部，北京\ 100088呼伦贝尔学院物理系，海拉尔\ 021008
Published: December 2020

The phenomenon of measure synchronization is an important property in coupl ed Hamiltonian systems. In this paper, we investigate the measure synchronizati on in a chaotic system, and the regularity of phase difference is also discusse d in the regular coupled systems and the chaotic coupled system.A new method is proposed for determining the critical coupled strength of transition to the mea sure synchronization. At the same time, we have studied the influence of Gaussi an white noise on the measure synchronization. It is significant to investigate the conservative system using the property of measure synchronization.
The complete analytical form and analysis on angular dispersion formula of two-dimensional grating
Authors: Bayanheshig  , Tang Yu-Guo  , Qi Xiang-Dong  ,   中国科学院长春光学精密机械与物理研究所,长春　130033
Published: December 2020

On the basis of the vector diffraction theory, the equation o f two_dimensional grating in arbitrary angle of incidence is given, the complet e analytical form of angular dispersion formula of two_dimensional grating is f irst ly deduced, and the concept of angular dispersion of diffractive polar angle (AD DPA)(the first kind angular dispersion) and angular dispersion of diffractive az imuthal angle (ADDAA) (the second kind angular dispersion) are established. In addition, according to theoretical analysis and numerical method on ADDPA and AD DAA of two_dimensional grating, the mechanism that diffraction spot array gener at es distortion is explained when the incidence wave has an angular deviation from the grating normal. Moreover, the conditions for causing mutation of ADDAA and l eading to the dramatic change of diffraction spot array are also determined. Thi s work, therefore, is of great importance in basic theory research. In practical ap plication, taking x_ray diffraction, low_energy electron diffraction and reflect ion high_energy electron diffraction of crystal and quantum d ot for example, we may take advantage of the above formula to test, analyz e and explain the structure of a crystal lattice and the crystal growth process, then we can find new methods of characterizing crystal structure.
Symmetry in spectrum space of isotonic oscillator and two-photon parametric model
Authors: Li Wen-Bo  , Li Ke-Xuan  , Li Ye  , Li Mi-Shan  , Li Ya-Ling  , Wen Xiao-Yang  , Yuan Guang-Jun  ,   北京交通大学物理系,北京　100044
Published: December 2020

Symmetry in spectrum space of isotonic oscillators is studied, and a distinct fi gure is given by appropriate parametric substitution. An analytic expression of normalized eigenfunction is obtained. It is proven that linear oscillator is a degeneration of isotonic oscillator. It is revealed that an isotonic oscillator is a two_photon parametric model. Coherent state of that model is given, and that coherent state includes odd_coherent state and even_coherent state constru cted by Glauber coherent states in a natural way.
Effects of detuning on the storage of a light pulse in an ultracold atomic medium
Authors: Huang Shan-Guo  , Gu Wan-Yi  , Ma Hai-Qiang  ,   (1)北京邮电大学光通信中心,北京　100876; (2)中国科学院物理研究所光物理实验室,北京　100080
Published: December 2020

Theoretical analysis and a full numerical simulation of the electromagnet ically induced transparency model are performed under detuning conditions for a closed three_level ultracold atomic system in which a signal field can be stored and retrieved. Numerical results confirm the theory that the system can be prep ared in dark states only under resonant conditions between the fields and the a tomic transitions. The signal field is partially stored in the ultracold atomic medium with the increase of detuning and an enhanced negative group velocity of t he physically vanishing signal pulse appears. In the case of a symmetrical detun ing (red or blue detuning), no remarkable changes of the storage process occur.
Yb3+doped double-clad fiber laser based on fiber Bragg grating
Authors: Fu Sheng－Gui  , Fan Wan－De  , Zhang Qiang  , Wang Zhi  , Li Li－Jun  , Zhang Chun－Shu  , Yuan Shu－Zhong  , Dong Xiao－Yi  ,   南开大学现代光学研究所，天津　300071
Published: December 2020

Fiber Bragg grating (FBG) was successfully fabricated in a Yb3+ doped double clad fiber with D-shaped inner-cladding by using phase mask method. Based on the FBG, a stable narrow line width double clad fiber laser was successfully demonstrated which resolved the output instability caused by mode-competition in common double-clad fiber lasers. The maximum output power is 570?mW at the wavelength 1058.2nm with 0.196nm line-band. Based on rate equations, the relationship between output power and pump power, the reflectivity of the FBG and the optimized length of the fiber were analyzed, which were in good agreement with the experimental results.
The molecular dynamics simulation of the effect of channel width on twodimensional granular flow
Authors: Hu Guo-Qi  , Zhang Xun-Sheng  , Bao De-Song  , Tang Xiao-Wei  ,   浙江大学物理系，杭州　310027
Published: December 2020

In this paper, we use the molecular dynamics simulation to study the phenomena that the granular flow changes from dilute flow to dense flow by increasing the channel width at a fixed orifice of 9.5d (d is the diameter of grains). In the area over the orifice, the density of flow increases and the granular temperatur edecreases with the increase of channel width. The change from dilute flow to dense flow begins at a channel width of 24d, a lower granular temperature( T/m＝0.05 J/kg) and a larger coordination number of 1.2 The mechanism is a structural change in the granular flow, since a wider channel results in more horizontal chains of particles and a lower temperature makes these chains more stable.
The formation of highdensity uniform silicon nanocrystalson insulator substrate and their surface morphology*
Authors: Li Xin  , Wang Xiao－Wei  , Li Xue－Fei  , Qiao Feng  , Mei Jia－Xin  , Li Wei  , Xu Jun  , Huang Xin－Fan  , Chen Kun－Ji  ,   南京大学物理系，固体微结构物理国家重点实验室，南京　210093
Published: December 2020

The method of pulsed laser induced nucleation combined with furnace annealing for crystal growth is successfully performed to fabricate uniform silicon nanocrys tals with high density from initial hydrogen amorphous silicon(aSi:H) ultra th in film, deposited by a plasmaenhanced chemical vapor deposition system. Ato mic force microscopy was employed to characterize the morphological modifications of samples. It is shown that the size of ncSi is increased as the laser fluence increased. Nano crystal silicon dots with lateral sizes of～10 nm in dia meter, size deviation less than 20% and with surface density about 10.11/cm2 are obtained. The growth mechanism of ncSi dots is also briefly discus sed.
A study of field emission of an array of multi-walled carbon nanotubes*
Authors: Song Jiao-Hua  , Zhang Geng-Min  , Zhang Zhao-Xiang  , Sun Ming-Yan  , Xue Zeng-Quan  ,   北京大学电子学系,北京　100871
Published: December 2020

Arrays of multi-walled carbon nanotube (MWCNT) were bombarded with argon ions a nd studied with transmission electron microscopy and x-ray photoelectron spectr oscopy. Our preliminary results show that after 35min ion bombardment, most of the MWCNT curls and the iron catalyst particles residing at the top end of the tube were knocked out. Although no obvious change in its emission images is obse rved, its field emission current considerably decreases. During spontaneous cool ing down from an elevated temperature (480℃), its emission current decreases sh arply. Interesting finding is that the coating of phosphor powder on the tin-oxide-coated glass anode significantly affects the emission current measurement . For example, the phosphor coating reduces the measured current by over 30?tim es and increases the turnon field from 1.0 to 2.0V/μm.
Wavefield forward modeling with the pseudo-spectral method in viscoelastic and azimuthally anisotropic media
Authors: Du Qi-Zhen  ,   石油大学（华东）地球资源与信息学院,东营　257061石油大学中国石油天然气集团公司物探重点实验室,北京　102249胜利油田有限公司物探研究院博士后科研工作分站，东营　257022
Published: December 2020

When a seismic signal propagates through a realistic medium in the Earth, in add ition to anisotropy, the layers may show intrinsic viscoelastic behavior. Thus, an accurate description of wave propagation requires a rheology that accounts for the anisotropic and viscoelastic behavior of rocks. On this basis, the pseudo spectral recursive formulae of viscoelastic and azimuthally anisotropic media are derived. Wavefield forward modeling with the pseudo-spectral method was car ried out in viscoelastic and azimuthally anisotropic media. The numerical results from the pseudo-spectral method clearly show that seismic wavefield is closely related with the viscoelasticity and the azimuth of the principal axes of anis otropy.
Symmetries and conserved quantities of mechanical systems with unilateral holonomic constraints in phase space
Authors: Zhang Yi  ,   苏州科技学院土木工程系，苏州  215011
Published: December 2020

The symmetries and conserved quantities of mechanical systems with unilateral holonomic constraints in extended phase space is studied. The differential equations of motion of the systems are established. The criterions of Noether symmetry, Lie symmetry and Mei symmetry are given, and the relations between the symmetries are researched. The Noether conserved quantity and two types of new conserved quantities, called the Hojman quantity and Mei quantity, for the systems are obtained, and intrinsic relations between the three symmetries and three types of conserved quantities are researched. An example is given to illustrate the application of the results.
The dynamical mechanism of A-B effect and its testing scheme
Authors: Wang Rui-Feng  ,   北京交通大学物理系,北京  100044
Published: December 2020

The dynamical mechanism of A-B effect is discussed in detail. It is found that A-B effect is due to the superposition of the magnetic field produced by the moving charges with that in the solenoid, rathor than the existence of vector potential A. If such a magnetic field superposition can be prevented, the A-B effect will disappear, even though the vector potential A still exists in space. To verify this conclusion, a new experimental scheme is suggested.