bluuebunny/crossref_metadata_2025 huggingface dataset:
Fractal character of noise in electromigration in metel interconnection
Authors: Chen Chun-Xia  , Du Lei  , He Liang  , Hu Jin  , Huang Xiao-Jun  , Wei Tao  ,   西安电子科技大学技术物理学院,西安 710071
Published: December 2020

Based on fractal theory , through the fractal dimension of electro-diffusion, the dimensions of noise time series and grain boundary are corelated. The change of noise dimension is shown to be useful for studying the damage mechanism and determining the parameters for electromigration. The picture of grain boundary becomes complicated in the early period of electromigration, but after the voids are informed, it becomes more regular. So the fractal dimension of time series increases during the early stage of electromigration and goes down after the voids are informed. The theoretical analysis is confirmed by experiment, the dimension of noise time series may be a new characteristic parameter for metallic interconnection electromigration.
Electroluminescence characteristics of a blend system based on a novel fluorene-carbazole copolymer and PVK doping system
Authors: Suo Fan  , Yu Jun-Sheng  , Deng Jing  , Jiang Ya-Dong  , Wang Rui  , Wang Wei-Zhi  , Liu Tian-Xi  ,   (1)电子科技大学光电信息学院电子薄膜与集成器件国家重点实验室,成都 610054; (2)复旦大学高分子科学系,上海 200433
Published: December 2020

The photoluminescent and electroluminescent characteristics of a blend polymer system consisting of a novel fluorene-carbazole copolymer (PFC) and poly(vinylcarbazole) (PVK) were investigated. Three OLED devices with the structures of indium-tin-oxide (ITO)/PVK:PFC/bathocuproine(BCP)/tris-(8-hydroxylquinoline)-aluminum (Alq3)/Mg∶Ag, indium-tin-oxide(ITO)/PFC/bathocuproine(BCP)/Alq3/Mg∶Ag and indium-tin-oxide(ITO)/PVK/ bathocuproine(BCP)/Alq3/Mg∶Ag respectively, were fabricated. The optoelectronic properties of the devices were measured. The results demonstrated that PVK in the blend system effectively restrained the formation of PFC excimers in solid films. Light emission of the device with blend system shifted with the variation of applied electric field, and variable color ranging from green to blue could be obtained. The luminance of blue light reached 1650cd/m2 when the drive voltage was higher than 7V. It was inferred that an energy transfer process from PVK to PFC might have occurred in this blend system.
Spontaneous formation of ordered Sn nanodot array on porous anodic alumina membrane
Authors: Huang Li-Qing  , Pan Hua-Qiang  , Wang Jun  , Tong Hui-Min  , Zhu Ke  , Ren Guan-Xu  , Wang Yong-Chang  ,   西安交通大学理学院,光信息科学与技术系,西安 710049
Published: December 2020

Highly ordered metal Sn nanodot arrays were prepared by vacuum electron beam evaporation using porous anodic alumina (PAA) membrane as the substrate. They were characterized by means of scanning electron microscopy (SEM) and X-ray diffraction (XRD). SEM images indicated that the Sn nanodot arrays are highly ordered and coincid with the contours of porous anodic alumina. The shape of Sn nanodot is spherical and the diameter approximates the pore diameter of the PAA membrane. XRD showed that crystallographic structures of Sn nanodot arrays are the same as the bulk Sn. The forming process and mechanism of the Sn nanodot array was discussed.
MOCVD growth and characteristics of high quality AlGaN used in the DBR structure of ultraviolet detector
Authors: Xie Zi-Li  , Zhang Rong  , Xiu Xiang-Qian  , Han Ping  , Liu Bin  , Chen Lin  , Yu Hui-Qiang  , Jiang Ruo-Lian  , Shi Yi  , Zheng You-Dou  ,   江苏省光电功能材料重点实验室,南京大学物理系,南京 210093
Published: December 2020

High quality AlGaN materials used in the DBR structure of ultraviolet detector are grown under different growth conditions. The structure, composition and photographic characteristics are determined by XRD, SEM and AFM. The influence of the growth conditions on the characteristics of the AlGaN materials are discussed.The good performance of the DBR structure of ultraviolet detector is obtained.
Entropy of Dirac field in a rectilinearly nonuniformly accelerating Kinnersley black hole
Authors: Yang Bo  ,   重庆三峡学院物理与电子工程学院,万州 404000
Published: December 2020

Using the Tortoise coordinate transformation and the Dirac field equation near the event horizon, the Hawking temperature of Kinnersley black hole is obtained. Meanwhile, adopting thin film brick-wall model, the entropy of Kinnersley black hole is calculated. The entropy near the event horizon is shown to be the entropy of black hole by regulating the cut-off parameter and the thin film's thickness properly. The results show that the entropy of the black hole is proportional to the area of the event horizon.
Complex variable reproducing kernel particle method for transient heat conduction problems
Authors: Chen Li  , Cheng Yu-Min  ,   (1)上海大学上海市应用数学和力学研究所，上海  200072; (2)上海大学上海市应用数学和力学研究所，上海  200072；长安大学理学院工程力学系，西安  710064
Published: December 2020

On the basis of reproducing kernel particle method(RKPM), the complex variable reproducing kernel particle method (CVRKPM) is discussed. The advantage of the CVRKPM is that the correction function of a 2-D problem is formed with 1-D basis function when the shape function is obtained. Then, we apply the complex variable method to two-dimensional transient heat conduction problems. In combination with the Galerkin weak form of transient heat conduction problems, the penalty method is employed to enforce the essential boundary conditions, the CVRKPM for transient heat conduction problems is investigated and the corresponding formulae are obtained. Compared with the conventional RKPM, the CVRKPM introduced in this paper has a higher precision and a lower computation cost. Some examples given in this paper verify the effectivity of the proposed method.
The Mei symmetry of discrete difference sequence mechanical system with variable mass
Authors: Huang Xiao-Hong  , Zhang Xiao-Bo  , Shi Shen-Yang  ,   (1)温州大学物理与电子信息学院,温州  325000; (2)浙江理工大学物理系,杭州  310018
Published: December 2020

The Mei symmetry and conserved quantity of a discrete difference sequence mechanical system with variable mass are studied in this paper. The form invariance of difference sequence equations for the discrete system under infinitesimal transformation groups is defined as Mei symmetry and the criterion when conserved quantities may be obtained from Mei symmetries is also presented. An example is given to demonstrate the applications of the results.
The interaction of ion-acoustic solitary waves in a two-dimensional hot ion plasma
Authors: Han Jiu-Ning  , Wang Cang-Long  , Li Sheng-Chang  , Duan Wen-Shan  ,   西北师范大学物理与电子工程学院，兰州  730070
Published: December 2020

Using the extended Poincar-Lighthill-Kuo perturbation method, we study the interaction between two ion-acoustic solitary waves with different propagation directions in a two-dimensional hot ion plasma, and obtain two KdV equations for solitary waves in both ξ and η directions. We also obtain the phase shifts and trajectories after the collision of two solitary waves with an arbitrary angle. The effects of the ratio of ion temperatures σ, the ratio of heat capacities γ and the angle α on the phase shifts are studied. The results suggest that these parameters can significantly influence the phase shift of the solitary waves. Moreover, there are compressive solitary waves in such a system.
Lag synchronization of autocatalytic chemical reaction in continuous stirred tank reactors
Authors: Li Yong  , Bi Qin-Sheng  ,   江苏大学理学院，镇江  212013
Published: December 2020

The problem of lag synchronization for chemical reaction system composed of two continuous stirred tank reactors is proposed. Based on Lyapunov stability theory, the controller which can make the reaction reach the lag synchronization state is obtained by suitably selecting the output and the synchronous signals. Numerical simulations are performed to demonstrate the effectiveness of the proposed scheme. Finally it is pointed out that there exist two different time scales in the error system of lag synchronization.
Stream cipher design based on inter-perturbations of chaotic systems
Authors: Xiang Fei  , Qiu Shui-Sheng  ,   华南理工大学电子与信息学院，广州  510640
Published: December 2020

A new stream cipher design scheme is proposed, which uses the sequences generated by two chaotic systems to inter-perturb their sequence values and the control parameter, so as to obtain a new sequence as key stream. Inter-perturbed sequence and Logistic sequence are tested by several tests of NIST's (National Institute of Standards and Technology) STS randomness test suite. Simulation results prove that the cryptographical properties of inter-perturbation sequence are better than those of Logistic sequence. k-error approximate entropy is proposed to test the stability of inter-perturbed sequence and Logistic sequence. Simulations indicate that the stability of inter-perturbed sequence is better than that of Logistic sequence. An image is encrypted and decrypted by the inter-perturbed sequence. Simulation results show that the inter-perturbation sequence can cover up plaintext effectively and safely.
Nuclear reaction stopping of 400MeV/nucleon 56Fe in water
Authors: Fang Mei-Hua  , Wei Zhi-Yong  , Yang Hao  , Cheng Jin-Xing  ,   (1)防化研究院第二研究所，北京  101105; (2)南京航空航天大学，南京  210016
Published: December 2020

Geant4 toolkit for Monte Carlo simulation is used in high energy heavy ion energy deposition simulation. The energy deposit of relativistic 400MeV/nucleon 56Fe has contributions from three sources, namely electronic stopping, nuclear stopping and nuclear reaction stopping. The electronic stopping and nuclear stopping are well known ionization, excitation and elastic collision of particles, the nuclear reaction stopping comes from the contribution of secondary particles emitted from nuclei during nuclear reaction. Yields of secondary particlesinduced by relativistic 56Fe in water and the energy deposited near the track are calculated.
Influence of parameter errors on the temperature measurement of cold atoms via short-distance time-of-flight absorption spectra
Authors: He Jun  , Wang Jing  , Qiu Ying  , Wang Yan-Hua  , Zhang Tian-Cai  , Wang Jun-Min  ,   山西大学光电研究所，量子光学与光量子器件国家重点实验室，太原  030006
Published: December 2020

The basic model and the experimental measurement method of short-distance time-of-flight absorption spectra for determining the temperature of cold atoms are described. Based on the realization of temperature measurement of cold cesium atoms in a magneto-optical trap，the influences of measurement errors of the three experimental parameters，namely the falling distance h，the initial Gaussian radius σ0 of the cold cloud, and the Gaussian radius σp of probe beam, on the determination of temperature have been analyzed and compared.
Loading and cooling of cesium atoms in 3D optical lattice
Authors: Qiu Ying  , He Jun  , Wang Yan-Hua  , Wang Jing  , Zhang Tian-Cai  , Wang Jun-Min  ,   山西大学光电研究所，量子光学与光量子器件国家重点实验室，太原  030006
Published: December 2020

A four-beam 3D near-resonant optical lattice system is implemented and cold atoms are loaded into the optical lattice based on cesium magneto-optical trap and optical molasses. The dependence of the final temperature due to the Sisyphus cooling on the intensity and the frequency detuning of optical lattice are experiemently investigated，and the lifetime of the cold atoms in optical lattice are measured via the short-distance time_of_flight absorption spectra.
2D array of surface optical micro-traps by evanescent wave interference
Authors: Wang Zheng-Ling  , Cao Guo-Rong  , Yin Jian-Ping  ,   (1)华东师范大学物理系，精密光谱科学与技术国家重点实验室，上海  200062; (2)江苏大学物理系，镇江  212013; (3)江苏大学物理系，镇江  212013；华东师范大学物理系，精密光谱科学与技术国家重点实验室，上海  200062
Published: December 2020

We propose a novel scheme to form a 2D surface array of optical micro-traps of cold atoms by using two sets of far red-detuned evanescent wave interference and a blue-detuned evanescent wave. The optical potentials of the 2D surface array of optical micro-traps are high enough to trap cold atoms released from the standard magneto-optical trap，and 87Rb atoms trapped in the array of optical micro-traps can be cooled to 2.56μK with efficient intensity-gradient Sisyphus cooling. Our study shows that the proposed 2D surface array of optical micro-traps can be used in atomic physics，atomic optics, quantum optics and so on.
The interaction of HD+2，H+3 and D+3 with solid foils and the three-body wake effect
Authors: Zhu Zhou-Sen  , Miao Jing-Wei  , Yuan Xue-Dong  , Shi Mian-Gong  , Liao Xue-Hua  ,   (1)四川大学原子核科学技术研究所，教育部辐射物理与技术重点实验室，成都  610064; (2)四川师范大学物理与电子工程学院，成都  610066
Published: December 2020

The mechanism to form HD+2，H+3 and D+3 from RF ion source is analyzed by experimental study of the interaction of these ions with solid foils. The structural pattern of HD+2 and the mean internuclear separations are determined using the Coulomb explosion technique. In our experiment，there is no line-shaped structure for HD+2. A theoretical model to deal with the wake effect of three-body Coulomb explosion is proposed and applied to the interaction of HD+2，H+3 and D+3 with solid foils. The model is proved to be successful and the structure of HD+2 is confirmed.
Density functional theory study on the structures and properties of (Ca3N2)n(n=1—4) clusters
Authors: Chen Yu-Hong  , Kang Long  , Zhang Cai-Rong  , Luo Yong-Chun  , Yuan Li-Hua  , Li Yan-Long  ,   (1)兰州理工大学，甘肃省有色金属新材料省部共建国家重点实验室，兰州  730050; (2)兰州理工大学物理系，兰州  730050; (3)兰州理工大学物理系，兰州  730050；兰州理工大学，甘肃省有色金属新材料省部共建国家重点实验室，兰州  730050
Published: December 2020

Possible geometrical structures and relative stabilities of (Ca3N2)n(n=1—4) clusters are studied by using the hybrid density functional theory (B3LYP) with 6-31G* basis sets. For the most stable isomers of (Ca3N2)n(n=1—4) clusters，the electronic structures，vibrational properties，bond properties，relative stabilities are analyzed. The following tendencies are revealed by the calculated results: the coordination number of N are usually 3—5. The bond lengths are about 0.231—0.251nm for Ca—N and 0.295—0.358nm for Ca—Ca. The population analysis suggests the average natural charges of N atoms are about -1.553e—-2.241e and those of Ca atoms about 1.035e—1.445e，the bonds between Ca and N are strongly ionic. The dynamic stability of Ca3N2 and (Ca3N2)3 clusters are higher than that of other clusters.
New scheme for introducing an oblique incidence plane wave to layered media in finite-difference time-domain
Authors: Jiang Yan-Nan  , Ge De-Biao  ,   西安电子科技大学物理系，西安  710071
Published: December 2020

In the application of two-dimensional finite-difference time-domain (2D-FDTD) method to the analysis of scattering by an object embedded in layered media，the obliquely incident wave along the total field-scattered field (TF-SF) contains the incidence pulse and the reflected and multiple-reflected wave，which can not be introduced by use of the traditional method. To solve this problem，a hybrid scheme using different ways to treat the four TF-SF boundaries is presented. The modified 1D-FDTD including oblique incidence angle is used to treat the longitudinal side boundaries，which can produce the reflected and multiple-reflected wave to layered interface automatically. The longitudinal side boundaries are extended downwards，such that the TF-SF lower boundary is located in the perfectly matched layer (PML) completely，thus the transmission wave and scattered wave are both outward-going waves in the lowest PML layer，and are absorbed by PML. The TF-SF upper boundary is located in free space; the incidence wave along it is in fact a properly time-delayed duplication of the waveform at the corner of TF-SF upper longitudinal boundary. The computational results show the reliability and applicability of the presented hybrid scheme.
A general method for finite difference time domain modeling of wave propagation in frequency-dispersive media
Authors: Wei Bing  , Ge De-Biao  , Wang Fei  ,   西安电子科技大学物理系，西安  710071
Published: December 2020

The analysis of electromagnetic scattering and propagation in dispersive media is complicated in time domain，because its dielectric property is frequency-dependent. A disadvantage of the prevailing algorithms is the need to deduce different formulations for each dispersion model. In this paper，the shift operator finite difference time domain (SO-FDTD) method is developed. First，we prove that the complex permittivity of three kinds of general dispersive media models，i.e. Debye model，the Lorentz model and the Drude model, may be described by rational polynomial functions in jω. By introducing a shift operator zt，the constitutive relation between D and E is derived in discretised time domain. The shift operator method is then applied to the general dispersive medium case. The recursive formulation for D and E available for FDTD computation is obtained. Finally，the scatterings by a dispersive sphere and a PEC object covered with dispersive media are computed. The computed results are in good agreement with the literature and the one obtained by Mies series solution. This illustrates the generality and the feasibility of the presented scheme.
Simulation on a new coupling method of laser diode array end-pumped large-aperture amplifiers
Authors: Deng Qing-Hua  , Peng Han-Sheng  , Sui Zhan  , Ding Lei  , Li Ming-Zhong  , Wang Jian-Jun  , Tang Jun  , Luo Yi-Ming  , Lin Hong-Huan  , Zhang Rui  , Deng Ying  , Lu Zhen-Hua  ,   (1)中国工程物理研究院激光聚变研究中心,绵阳  621900; (2)中国工程物理研究院院机关,绵阳  621900
Published: December 2020

A new coupling method is put forward for high power LDA end-pumped large-aperture amplifiers. The LDA is inscribed on a sphere and then a duct is added adjacent to it. Three-dimensional ray-tracing program is used to simulate the features of the new coupling method. Simulation results show that when the area contraction coefficient is about 30, deposition efficiency in the gain media as high as 93.7% can be achieved; When the emitting area is not less than the aperture of the duct, uniform and top-hat distribution is obtained. When several stacks are spliced to make an inscribing area, amplifiers with larger aperture can be end pumped. When stacks in LDA is placed as m×n(m≠n) arrays, uniform and top-hat distribution is also obtained. In the LDA coupling experiment, the output is top-hat distributed at the end of the duct and the coupling efficiency is 85.4%.
Preparation and performance of Cr3+/Tm3+/Ho3+ co-doped fluorophosphate glasses
Authors: Lü Jing-Wen  , Liu Shuang  , Xiao Hong-Liang  , Zheng Xiao-Qiu  , Li Yue  , Li Feng  ,   长春理工大学材料科学与工程学院,长春  130022
Published: December 2020

Fluorophosphate glasses with various Al(PO3)3 contents were prepared，and their structure,thermal properties and spectral properties were studied.The emission properties at around 2.0μm of Cr3+/Tm3+/Ho3+ co-doped fluorophosphate glasses with different mole fractions of Tm3+ and Ho3+were studied. The spectral strength parameters Ωt(t=2,4,6) of those glasses have been calculated. Meanwhile,the spectral parameters, including the oscillator strength,spontaneous emission probability and branching ratios of Ho3+, have been calculated. The results show that the 2.0μm emission intensity gradually grows higher with the increase of the mole fraction of Tm3+. The Tm3+→(3F4) →Ho3+(5I7) energy transfer in (Tm3+/Ho3+) co-doped fluorophosphate glasses is very efficient, and it is dependent on the doping concentration.
Phase properties of photonic crystal heterostructure and its applications
Authors: Wu Kai-Shun  , Long Xing-Teng  , Dong Jian-Wen  , Chen Di-Hu  , Wang He-Zhou  ,   中山大学光电材料与技术国家重点实验室，广州  510275
Published: December 2020

It is revealed that the reflectance in the whole stop band of a heterostructure, including the defect mode, approaches 1; while the phase-shift depends on the sub-photonic crystal (PC) that faces the incident direction. For every sub-peak in the defect mode or every pass band of the sub-PC facing the incident direction, the phase shift is 2π. These properties are useful for designing optical phase devices several orders more sensitive than those using amplitude-signal. In this paper, a sensitive optical phase logic gate (NAND) is described as an example of optical phase devices. Moreover, these properties are also useful for the study of related physical phenomena.
Control of dispersion in microring coupled-resonator optical waveguides
Authors: Tian He  , Zhang Yun-Dong  , Wang Hao  , Qiu Wei  , Wang Nan  , Yuan Ping  ,   哈尔滨工业大学光电子技术研究所，哈尔滨  150080
Published: December 2020

We calculated the dispersion relation of microring coupled-resonator optical waveguides using transfer matrix method and discussed its dependence on the coupling loss, transmission loss and coupling coefficient. The shape, position and bandwidth of dispersion relation could be controlled by changing the coupling loss, transmission loss and coupling coefficient. The adjustment and control of dispersion relation is important for applications of coupled-resonator optical waveguides in filtering, delay and buffer of optical signal.
High energy femtosecond soliton mode-locking laser based on Yb-doped single polarization large-mode-area photonic crystal fiber
Authors: Song You-Jian  , Hu Ming-Lie  , Liu Bo-Wen  , Chai Lu  , Wang Qing-Yue  ,   天津大学精密仪器与光电子工程学院，光电信息技术科学教育部重点实验室，天津  300072
Published: December 2020

A high energy femtosecond fiber laser based on Yb-doped single polarization large-mode-area photonic crystal fiber is demonstrated. A simple linear laser cavity is used. The laser works in soliton mode-locking regime due to the negative dispersion generated by a pair of gratings implemented in the cavity, while the self-starting mode-locking operation is achieved by sermiconductor saturable absorber mirror. The fiber laser directly generates 518 fs laser pulses with the average power of 700 mW at the repetition rate of 47.3MHz (corresponding to a pulse energy of 14.8 nJ). The single pulse energy is two orders higher than that of conventional soliton mode-locking fiber laser.
Equivalent rectangle approximation-staircase concatenation method for wedge shaped fiber
Authors: Liu Xu  , Chen Lin  , Sun Xiao-Han  ,   东南大学电子科学与工程学院，光子学与光通信研究室，南京  210096
Published: December 2020

Wedge shaped fiber (WSF) is the key component to acquire high coupling efficiency between input/output ports of planar lightwave circuit chips and fiber arrays. It is very important to analyze the mode spot and the mode field evolution of the lightwave propagating in WSF using numerical simulation tools. A three_dimensional equivalent rectangle approximation-staircase concatenation method (ERA-SCM) is proposed to fractionize the wedged tip of WSF along the propagating direction and introduce rectangular waveguide approximation so that effective index of the segmentations is obtained and SCM analysis model is established. Lightwave propagation and mode field evolution is analyzed by ERA-SCM and compared with finite difference-beam propagation method (FD-BPM), showing that the former is more precise to solve mode field evolution for asymmetric fiber and waveguide structures. The measurement of the output optical spot verifies the ERA-SCM simulation error is within 1.9%, while that for FD-BPM method is 4.5%. Thus, ERA-SCM is an effective method for analyzing asymmetric fiber and waveguide structures.
Multi-scale simulation of the dynamic behaviors of nano-void in shocked material
Authors: Chen Jun  , Xu Yun  , Chen Dong-Quan  , Sun Jin-Shan  ,   北京应用物理与计算数学研究所计算物理实验室，北京  100083
Published: December 2020

In this paper, the multi-scale numerical simulation method was used to simulate the dynamic behaviors of nano-void in metal Al under shock loading. This method couples the molecular dynamics method used in local defect domain and the finite element method used globally by using a bridge-scale function. Based on the calculated strain field and temperature field and atom positions, we reveal that the collapse of nano-void depends on the yield strength of materials and shock loading strength. And compression process of void is the main reason of formation of local hot spot. Meanwhile, the dislocation and hot spot induced by void collapse lead to the easy formation of the local adiabatic shear band.
Application of planar laser induced fluorescence in the investigation of the stagger electrode dielectric barrier discharge plasma
Authors: Li Gang  , Xu Yan-Ji  , Mu Ke-Jin  , Nie Chao-Qun  , Zhu Jun-Qiang  , Zhang Yi  , Li Han-Ming  ,   (1)中国科学院工程热物理研究所先进能源动力重点实验室，北京  100080; (2)中国科学院物理研究所光物理实验室，北京  100190
Published: December 2020

Trace nitric oxide produced by dielectric barrier discharge was detected directly by the planar laser induced fluorescence system. Through numerical simulations, both the experimental results and the mechanism of plasma flow control were discussed briefly. Besides, flow induced by the dielectric barrier discharge plasma was visualized by the planar laser induced fluorescence system.
Two-dimensional particle-in-cell simulation of the ion sheath dynamics in plasma source ion implantation of a hemispherical bowl-shaped target
Authors: Liu Cheng-Sen  , Wang De-Zhen  , Liu Tian-Wei  , Wang Yan-Hui  ,   (1)大连理工大学物理与光电工程学院，三束材料改性国家重点实验室,大连  116023; (2)辽宁师范大学物理与电子技术学院,大连  116029; (3)中国工程物理研究院表面物理与化学国家重点实验室,绵阳  621900
Published: December 2020

Plasma source ion implantation into a hemispherical bowl-shaped target is simulated by the two-dimensional particle-in-cell method. The numerical procedure is based on solving the Poisson's equation on a grid and tracing the movement of the ions through the grid. The potential and the ion density distributions in the sheath are studied in detail and the trajectories and dynamic states of ions are considered. The implantation dose and impact angle of the ions at different parts of the target surface are obtained. The ion focusing effect due to the nonuniformity of the sheath potential near the brim of the vessel is observed. The results presented here show that the ion focusing causes the nonuniformity of dose on the target surface.
Photon acceleration in the laser wakefield
Authors: Wang Jian  , Gu Yu-Qiu  , Cai Da-Feng  , Jiao Chun-Ye  , Wu Yu-Chi  , He Ying-Ling  , Teng Jian  , Yang Xiang-Dong  , Wang Lei  , Zhao Zong-Qing  ,   (1)内江师范学院物理学与电子信息工程系,内江  641112; (2)四川大学原子与分子物理研究所,成都  610065; (3)中国工程物理研究院激光聚变中心高温高密度等离子体国家重点实验室，绵阳  621900; (4)中国工程物理研究院激光聚变中心高温高密度等离子体国家重点实验室，绵阳  621900；四川大学原子与分子物理研究所,成都  610065
Published: December 2020

On the SILEX-Ⅰlaser facility, we measured the transmission spectra after ultrashort and ultraintense laser pulse interaction with tenuous plasma. Due to the existence of the wakefield, the time-dependent refractive index of the plasma can accelerate or decelerate photons of laser pulse when the laser pulse propagates in the plasma. Its main features are the spliting of the fundamental frequency and its evident broadening in the laser transmission spectra.The side_band wave which is often associated with Raman and Self modulation were not observed in our experiments. Utilizing the LPIC++ code, we also simulated the transmission spectrum after the ultrashort_ultrahigh intensity laser pulse interacts with the tenuous plasma. The simulation results are in good agreement with the experiment results.
Effect of thermal initiator concentration on piezoresistivity of polymer-derived amorphous silicon carbonitrides
Authors: Wang Yan-Song  , Wang Wen-Quan  , Yuan Zhou  , Zhang Li-Gong  , Xu Shi-Feng  ,   (1)吉林大学物理学院，长春  130023; (2)吉林大学物理学院，长春  130023；中国科学院物理研究所磁学国家重点实验室，北京  100190; (3)中国科学院长春光学精密机械与物理研究所激发态物理重点实验室，长春  130033；中国科学院研究生院，北京  100049; (4)中国科学院研究生院，北京  100049
Published: December 2020

Piezoresistivity of polymer-derived silicon carbonitrides made from a polysilazane modified with different amounts of thermal initiator is measured at room temperature. It is found that the thermal initiator has a significant effect on the electric conductivity, which first increases and then decreases with increasing thermal initiator concentration. The highly conductive sample exhibits much higher piezoresistive coefficient as compared with the low conductive samples. The microstructures of the materials are characterized using Raman spectroscopy. Based on these results, the piezoresistive behavior is described using the tunneling-percolation mechanisms, the piezoresistive effect of SiCN ceramics is controlled by the concentration and distribution of free carbon clusters, and the effect of thermal initiator on the formation of free carbon clusters in the materials is discussed.
Effect of boron doping on the electrical conduction of tetrahedral amorphous carbon films
Authors: Tan Man-Lin  , Zhu Jia-Qi  , Zhang Hua-Yu  , Zhu Zhen-Ye  , Han Jie-Cai  ,   (1)哈尔滨工业大学复合材料与结构研究所，哈尔滨  150018; (2)哈尔滨工业大学深圳研究生院，深圳  518055; (3)哈尔滨工业大学深圳研究生院，深圳  518055；哈尔滨工业大学复合材料与结构研究所，哈尔滨  150018
Published: December 2020

Boron doped tetrahedral amorphous carbon films were prepared on a filtered cathodic vacuum arc deposition system by varying the weight percentage of boron in the mixed graphite cathodes. The electrical conductivity versus temperature, I-V characteristic and C-V characteristic for the films were measured by four-probe method, impedance/gain-phase analyzer, and electrochemical interface, respectively. As the boron content increases from 0 to 6.04 at%, the electrical conductivity of the films at room temperature increases gradually and then drops down, while the activation energy varies in the reverse. At the boron content of 2.13 at%, a maximum value of 1.42×10-7 S/cm and a minimum value of 0.1eV were obtained for the above two parameters, respectively. Furthermore, the rectification characteristics in the I-V curve indicated a p-n junction diode was formed for the boron doped tetrahedral amorphous carbon/n-type silicon heterojunction with uniform doping levels in the space at the two ends of the junction.
Research on the temperature stability of triangular ferromagnetic nanowire arrays using the damage spreading method
Authors: Guo Zi-Zheng  , Xuan Zhi-Guo  , Zhang Yuan-Sheng  , An Cai-Hong  ,   内蒙古师范大学物理与电子信息学院，呼和浩特  010022
Published: December 2020

The temperature stability of the quantum magnetic disk constructed on a triangular manowire array is studied by the damage spreading method. Three aspects are considered in order to make the Ising model more realistic. Firstly, we include the long-range interaction between spins. Secondly, we take into account the disorder of the nanowire lengths. At last, we present an estimation of the spin interaction constant through the system coercive force by deriving the relation between the spin interaction constant and the coercive force. It is shown that the longer the spin interaction acts, the more stable the system becomes. On the other hand, the system has greater temperature instability when the disorder degree of the nanowire lengths is increased.
Effect of spin polarization on electron recombination dynamics in bulk intrinsic GaAs
Authors: Teng Li-Hua  , Yu Hua-Liang  , Huang Zhi-Ling  , Wen Jin-Hui  , Lin Wei-Zhu  , Lai Tian-Shu  ,   中山大学光电材料与技术国家重点实验室，物理科学与工程学院，广州  510275
Published: December 2020

Time-resolved circularly polarized and linearly polarized pump-probe spectroscopies are used to study the recombination dynamics of spin-polarized and spin-nonpolarized electrons as well as its evolution with photon energy for an intrinsic GaAs at 9.6K. It is found that the spin polarization has a significant influence on the electron recombination dynamics. The spectroscopic measurements give the same recombination lifetime only when measured near the bottom of the conduction band, but different recombination lifetimes were measured in higher excess-energy states. It is pointed out that the recombination lifetime measured by circularly polarized pump-probe spectroscopy, rather than that measured by linearly-polarized pump-probe spectroscopy, should be used to solve for the lifetime of electron-spin coherence from time-resolved Faraday spectroscopic data. The theoretical calculation agrees well with the experimental results.
Effect of annealing and Mg content on the microstructure and optical properties of Zn1-xMgxO films
Authors: Zhou Jun  , Fang Qing-Qing  , Wang Bao-Ming  , Liu Yan-Mei  , Li Mao  , Yan Fang-Liang  , Wang Sheng-Nan  ,   安徽大学物理与材料科学学院，光电信息获取与控制教育部重点实验室，合肥  230039
Published: December 2020

The MgxZn1-xO(x=0.1,0.2,0.3, 0.4,0.5,0.6 and 0.7)thin films were prepared on glass substrate by the Sol-Gel method. The X-ray diffraction results show that when the value of x is between 0.1 and 0.3, the thin film has the structure of hexagonal wurtzite while the angle of diffraction peak becomes bigger with increasing x, and the MgO impurity phase segregates at x=0.4. The ultraviolet photoluminescence spectra of the films show ultraviolet emission peak at room temperature, which has an increasing blue shift with the increasing content of Mg. The band gap of ZnO broadens with Mg-doping concentration increasing from 0.1 to 0.3. For the sample with x=0.1 annealed at 500℃, the crystal quality of the films is improved with the increase of the rate of temperature rise from 4.5℃/min to 6.0℃/min. For the sample with x=0.2, the crystal quality of the films is improved with the increase in annealing temperature from 500℃ to 560℃. With the annealing temperature increasing above 590 ℃ the crystal quality of the films degenerates.
Numerical simulation of probe induced surface plasmon resonance coupling nanolithography
Authors: Hong Xiao-Gang  , Xu Wen-Dong  , Li Xiao-Gang  , Zhao Cheng-Qiang  , Tang Xiao-Dong  ,   (1)华东师范大学信息科学技术学院，上海  200241; (2)中国科学院上海光学精密机械研究所，上海  201800
Published: December 2020

A new nanolithographic technology, the probe induced surface plasmon resonance coupling nanolithography (PSPRN), is presented and analyzed numerically by using finite difference time domain method for the loss and dispersive materials. The PSPRN uses a fundamental mode Gaussian beam with wavelength of 514.5nm to excite the Kretschmann surface plasmon resonance, and utilizes the metal probe local-field enhancement effect to realize nanolithography. The influences of different distances between probe and recording layer and different sizes of tip on local field enhancement and the distribution of electric field intensity amplitude on the surface of recording layer were investigated. Results show that the local field enhancement effect is most significant and the electric field intensity amplitude contrast ratio is maximal when the probe is in contact with the recording layer. When the distance between tip and recording layer is 5nm, the distribution width of the relative electric field intensity amplitude above the critical value for near-field nanolithography on the surface of recording layer is close to the size of the tip.
The method of decomposing wind field in a limited area and its application to typhoon SAOMEI
Authors: Zhou Yu-Shu  , Cao Jie  , Gao Shou-Ting  ,   (1)中国科学院大气物理研究所，北京  100029; (2)中国科学院大气物理研究所，北京  100029；中国科学院研究生院，北京  100049
Published: December 2020

The harmonic-cosine series expansion method (H-C method) for horizontal wind is introduced. It divides a function, such as horizontal wind, stream function and velocity potential, into two parts. One is a harmonic function which is the solution of a Laplace equation with nonzero boundary condition, and thus can be called the harmonic part. It is also been called the external part since it is independent of any values inside the limited area. The other is the difference of the original wind and the harmonic part, which is the solution of Poisson equation with homogeneous boundary condition and can be expanded into double Fourierism cosine series. It only depends on vorticity or divergence inside the limited area, so it is also called the inner part. The H-C method uses a spectrum approach in calculating derivatives, so it is more precise than the differential ones. The boundary condition given to solve the harmonic part has definite physical meaning and it is well handled in solving stream function and velocity potential in a limited area. Therefore, problems such as the instability in the calculation, the original wind field not being able to be reversed accurately, and the system deficiencies on the boundary occurring in previous methods, are successfully overcome. Using the NCEP/NCAR 1°×1° analysis data with a time resolution of 6 h, the Regional Spectrum Model (RSM) reanalysis data from Japan Meteorological Agency with a horizontal resolution of 20km and a time interval of 6 h, we decompose the horizontal wind of super-intensity Typhoo SAOMEI (0608) based on the H-C method. The two parts are called the nondivergent and the irrotational components, respectively. Analyses of the two parts indicate that the typhoon center marked by the nondivergent component at lower levels approaches more closely the observed center than the original wind did. In addition, the nondivergent wind can clearly manifest the water transporting passageway. The phenomenon that horizontal winds converge at lower levels and diverge at upper levels is more obvious in irrotational wind field than that in the original one. Convective activities at the South China Sea and in the west of Philippines confront the development of SAOMEI by blocking off its water transport after it landed. It may be a reasonable explanation for the fact that SAOMEI weakened so rapidly despite of its landing as a super-intensity typhoon. Before it landed, the nondivengent and irrotational centers in wind component fields are not always in the same location. It can only be seen by using the decomposing method for horizontal winds. The two components derived from the H-C method may provide more detailed characteristics than the original wind does. Therefore, this approach would be important in understanding the characteristics of typhoon and can be used widely in the future.
Quasi-linear diffusion of the radiation belt energetic electrons by ground-based HF heater-induced ELF/VLF emissions
Authors: Gu Xu-Dong  , Zhao Zheng-Yu  , Ni Bin-Bin  , Wang Xiang  , Deng Feng  ,   (1)Department of Mathematics and Statistics,Memorial University,St. John's,A1C 5S7,NL,Canada; (2)武汉大学电子信息学院空间物理系,武汉  430079
Published: December 2020

The dynamics of energetic electron fluxes in both the inner and the outer radiation belts is very important with respect to satellite protection, in particular for low and middle-orbit satellites. Based on the quasi-linear theory of gyroresonant wave-particle interaction, we compute the diffusion coefficients and loss timescales for radiation belt energetic electrons due to cyclotron resonance with artificial ELF/VLF emissions that are radiated through modulating the currents in the lower ionosphere by ground-based powerful high-frequency (HF) transmitter. We test the electron pitch-angle scattering in the outer zone, typically at L=4.6 (where the HAARP facility is located) and in the inner zone, typically at L=1.5. The results indicate that the electron loss timescales due to artificial injection of ELF/VLF waves in the inner and the outer radiation belts depend largely on the value of the cold-plasma parameter α*(∝B2/N0, where B is the ambient magnetic field and N0 the electron number density), the properties of wave frequency spectrum, the wave power and the electron energy in resonance with the waves. Generally, relativistic electrons in the outer zone are much easier to be precipitated into the atmosphere by artificial ELF/VLF whistler waves and lower-energy electrons (≤200keV) can undergo pitch-angle scattering more efficiently than higher-energy electrons (≥500keV). Since ELF/VLF waves can experience in situ amplification due to multiple magnetospheric reflections within the magnetospheric cavity, it can be reasonably expected that, under suitable situations, ground-based HF transmitters can provide feasible radiation power into the ionosphere to induce the injection of ELF/VLF waves into the inner magnetosphere, and consequently account for potential rapid removal of outer belt relativistic electrons in a timescale of from 1 to 3 days and of inner belt relativistic electrons that generally have a lifetime of 100 days or more in a timescale of the order of 10 days.
Two types of conserved quantities of Lie-Mei symmetry for a variable mass system in phase space
Authors: Liu Yang-Kui  , Fang Jian-Hui  ,   (1)陇东学院物理与电子工程学院，庆阳  745000; (2)中国石油大学物理科学与技术学院，东营  257061
Published: December 2020

Two types of conserved quantities deduced by Lie-Mei symmetry of variable mass mechanical system are studied in phase space in the paper. The definition and criterion of Lie-Mei symmetry for the system are given. A coordination function is introduced，and the conditions under which the Lie-Mei symmetry leads to the two types of conserved quantities and the forms of the two types of conserved quantities are obtained. An illustrative example is given. The coordination function can be selected according to the requirement for finding the gauge function，and the choice of the coordination function is multiformal，so more conserved quantities can be deduced from Lie-Mei symmetry of the system.
Lie symmetry and conserved quantities of Nambu mechanical systems
Authors: Zhang Kai  , Wang Ce  , Zhou Li-Bin  ,   (1)西安工业大学数理系，西安  710032；西北大学现代物理研究所，西安  710069; (2)西北大学物理系，西安  710069
Published: December 2020

In this article，Lie symmetry of Nambu mechanical systems is discussed and its determining equations are established. Consequently，the structure equation and the associated conserved quantities are obtained. The inverse problem of Lie symmetries of the systems is also studied. As an example，Euler equations are used to illustrate the application of the main results.
Numerical simulation of liquid drop phenomenon by least square particle finite element method
Authors: Tang Bo  , Li Jun-Feng  , Wang Tian-Shu  ,   清华大学航天航空学院，北京  100084
Published: December 2020

A least square particle finite element method is presented and used to simulate the impact and splash of 2D water droplets on the water surface. This algorithm is based on an upgraded Lagrangian framework. An extended Delaunay triangulation method is used to get the new mesh at every time step. An alpha-shape method is used to deal with the splash and impact of the free surface. The least square finite element method is applied to solve the Navier-Stokes equations. An adaptive time step algorithm is derived to improve the efficiency and the robustness of calculation，and a mesh pulling scheme is introduced to improve the conservation of the total mass. Finally，when compared with the commercial Flow-3d code，the computational results achieve good agreement. Moreover，the free surface is more accurate and more clearcut than that of the Eulerian description based Flow-3d code.
The existence and uniqueness of the global solution for the viscoelastic-plate equation under nonlinear boundary conditions
Authors: Wang Dan-Xia  , Zhang Jian-Wen  , Wu Run-Heng  ,   (1)北方工业大学理学院，北京  100041; (2)太原理工大学理学院，太原  030024
Published: December 2020

In this paper，we consider the viscoelastic-plate equation under non-linear boundary conditions. Firstly，by the aid of Galerkin method，under non-linear boundary conditions (a) and the initial values w0∈W，and w1∈W，we prove the existence and uniqueness of a global weak solution w(t) for the initial boundary value problems. Secondly，under non-linear boundary conditions (b) and the initial values w0∈W，and w1∈W1，the existence and uniqueness of a global weak solution w(t) is also proved by using Galerkin method.
The temperature effect of the parabolic linear bound potential quantum dot qubit
Authors: Chen Ying-Jie  , Xiao Jing-Lin  ,   (1)内蒙古民族大学物理与机电学院，通辽  028043; (2)曲阜师范大学物理工程学院，曲阜  273165
Published: December 2020

On the condition of electric-LO phonon strong coupling in parabolic quantum dot，we obtain the eigenenergy and the eigenfuctions of the ground state and the first-excited state by using variational method of Pekar type. This system in quantum dot may be employed as a two-level quantum system-qubit. When the electron is in the superposition state of the ground state and the first-excited state，we obtain the space-time evolution of the electron density. It is shown that the electron density increases with the temperature when the temperature is lower，and the electron density decreases with the temperature when the temperature is higher. At the same time，we found that sometimes the electron density vibrates with the temperature，and its change is slowed down with the strength of coupling increasing.
The time-delay effect of a metapopulation
Authors: Li Jiang-Cheng  , Mei Dong-Cheng  ,   云南大学物理科学技术学院，昆明  650091
Published: December 2020

The simplified incidence function model with small delay time was employed to study the stability and mean extinction time of a metapopulation. By numerically computing the mean passage time and analyzing the stationary probability distribution function of the metapopulation，we found that：1) As delay time increases，the probability that pathe are occupied by a metapopulation decreases; 2) As delay time increases，the mean extinction time of a metapopulation decreases.
Circuit experimentation for a complicated hyperchaotic Lü system
Authors: Liu Yang-Zheng  , Jiang Chang-Sheng  , Li Xin-Chao  , Sun Han  ,   (1)南京工程学院非线性物理研究所，南京  211167; (2)南京航空航天大学自动化学院，南京  210016; (3)南京航空航天大学自动化学院，南京  210016；南京工程学院非线性物理研究所，南京  211167
Published: December 2020

A four-dimensional interrelated and switchable Lü hyperchaotic system is built by adding an additional state into the three-dimensional Lü chaotic system. When subsystems are hyperchaotic，an identical system parameter is determined according to the bifurcation diagrams of these subsystems. Some of its basic dynamical properties are studied detailedly，such as the feature of equilibrium，the phase portraits of hyperchaotic attractor，the Lyapunov exponent and fractal dimension. A practical circuit is designed to realize these systems. Experimental result shows the effectiveness and feasibility of the theoretical analysis and verifies the behavior of various attractors.
A new approach to synchronization between two different chaotic systems with parametric perturbation
Authors: Han Min  , Niu Zhi-Qiang  , Han Bing  ,   大连理工大学电子与信息工程学院，大连  116023
Published: December 2020

The problem of chaotic synchronization between two different chaotic systems with parametric perturbation is studied. Based on Lyapunov stability law and norm theory，a sufficient condition to synchronize two different chaotic systems with parametric perturbation is given and a general way of choosing the controller is proposed. This method can realize the synchronization of two chaotic systems with parametric perturbation if the dimensions of the chaotic systems are equal and the state variables are measurable. And it is required that the control must decay to zero together with the errors as soon as the synchronization is reached. The proposed method is robust and can be used widely. Numerical simulations of synchronization between two chaotic systems，and synchronization between two hyperchaotic systems are provided to show the effectiveness and feasibility of the method.
Suppression of spiral wave in the excitable media by using intermittent feedback scheme
Authors: Yin Xiao-Zhou  , Liu Yong  ,   (1)连云港职业技术学院,连云港  222006; (2)盐城师范学院数学科学学院,盐城  224051
Published: December 2020

A class of intermittent feedback scheme is proposed to eliminate the spiral wave in the excitable media, which is described by the Fitz-Hugh-Nagumo equation. The activators of the sites is observed and compared with the selected threshold (less than the maximum activator), a negative feedback is imposed on the whole system by inputting linear negative variable into the equation only when the sampled activator exceeds the threshold. It is found that the spiral wave is easier to be removed and the whole media becomes homogeneous when all the sites are monitored and smaller threshold is used, and the spiral wave just becomes sparse and breakup of spiral wave can be observed when the threshold is not small. On theother hand, weaker intensity of feedback still causes the spiral wave to be removed and the whole media still can become homogeneous when only one site is monitored. The controller will stop working as the whole media become homogeneous synchronically.