bluuebunny/crossref_metadata_2025 huggingface dataset:
Thickness effect on structure and magnetic properties of La0.8Ca0.2MnO3/SrTiO3 films
Authors: Zhang Hong-Di  , An Yu-Kai  , Mai Zhen-Hong  , Gao Ju  , Hu Feng-Xia  , Wang Yong  , Jia Quan-Jie  ,   (1)香港大学物理系，香港; (2)中国科学院高能物理研究所，北京 100049; (3)中国科学院物理研究所国家凝聚态物理实验室，北京 100080
Published: December 2020

The thickness dependence of strain and magnetic properties of La0.8Ca0.2MnO3 (LCMO) thin films grown on SrTiO3 (STO) substrates were investigated by X-ray diffraction techniques and magnetic measurements. The results show that all the LCMO films are well oriented in the (00l) direction on the (001) STO substrate. The LCMO thin films have a pseudo-cubic structure. With the film thickness increasing, the in-plane lattice parameters decrease while the out-of-plane lattice parameter increases. The lattice parameter a is close to b, but a little smaller than c. The in-plane strain in the film is tensile due to the lattice mismatch between the LCMO film and STO substrate, whereas that out-of-plane is compressive. The LCMO films have a slightly perceptible mosaic structure along the qz direction, and there exists an angular deviation of about 0.1° between ［001］LCMO and ［001］STO. The physical properties of the films strongly depend on the film thickness. With the increase of the film thickness the TMI is enhanced, and the MR is weakened.
Luminesce properties of the single white emitting phosphor Eu2+, Mn2+ co-doped Ca2SiO3Cl2
Authors: Yang Zhi-Ping  , Liu Yu-Feng  , Wang Li-Wei  , Yu Quan-Mao  , Xiong Zhi-Jun  , Xu Xiao-Ling  ,   (1)91550部队，大连  116023; (2)河北大学物理科学与技术学院，保定  071002; (3)河北大学物理科学与技术学院，保定  071002;河北省保定市第一中学，保定  071002; (4)江西财经大学电子学院，南昌  330013
Published: December 2020

The intense white emitting phosphors Ca2SiO3Cl2:Eu2+, Mn2+ were synthesized by traditional high temperature solid state reaction，and their luminesce properties were studied. The results indicate that the emission band consists of three peaks located at 425 nm，498 nm and 578 nm, respectively. The emission peaks at 425 and 498 nm originate from the transition 5d→4f of Eu2+ ions that occupy the two Ca2+ sites in the crystal of Ca2SiO3Cl2, while the 578 nm emission is attributed to the energy transfer from Eu2+ ions to Mn2+ ions. The white light can be obtained by mixing the three emission colors of blue (425 nm), green(498 nm) and red(578 nm) in the single host. The excitation spectra of the three emission colors all extend from 250 nm to 420 nm, and their peaks positioned around 370 nm, 385 nm, 396 nm and 412 nm, respectively. The phosphor can be excited effectively by InGaN chip in the range of 350—410 nm. The experiment results show that the Ca2SiO3Cl2: xEu2+, yMn2+ is a single host phosphor with superior properties for use in white light emitting diode (w-LED).
Effects of annealing on the photoluminescence of He ion implanted sapphire after 230 MeV Pb ion irradiation
Authors: Song Yin  , Wang Zhi-Guang  , Wei Kong-Fang  , Zhang Chong-Hong  , Liu Chun-Bao  , Zang Hang  , Zhou Li-Hong  ,   中国科学院近代物理研究所,兰州  730000
Published: December 2020

Single crystal sapphire (Al2O3) samples implanted with 110 keV He and irradiated at 320 K by 208Pb27+ ions with energy of 1.1 MeV/u to the fluences ranging from 1×1012 to 5×1014 ion/cm2 and subsequently annealed at 600, 900 and 1100 K. The obtained PL spectra showed that emission peaks centred at 375, 390, 413, and 450 nm appeared in irradiated samples. The peak of 390 nm became very intense after 600 K annealing. The peak of 390 nm weakened and 510 nm peak started to build up at 900 K annealing, the peak of 390 nm vanished and 510 nm peak increased with the annealing temperature rising to 1100 K. Infrared spectra showed a broadening of the absorption band between 460 cm-1, and 510 cm-1 indicating strongly damaged regions being formed in the Al2O3 samples and position shift of the absorption band at 1000—1300 cm-1 towards higher wavenumber after Pb irradiation.
Hop-parameter chaotic synchronization and its applications
Authors: Zhang Yong  , Chen Tian-Qi  , Chen Bin  ,   (1)电子科技大学电子工程学院，成都  610054; (2)电子科技大学电子工程学院，成都  610054;江西财经大学，南昌  330013
Published: December 2020

In this paper, we build a mathematic model of hop-parameter chaotic synchronization, propose and prove its sufficient condition, then analyze theoretically the condition for its realization. An efficient algorithm is proposed for about the hop-parameter chaotic synchronization and hop-parameter period synchronization. Based on the Chua's system, we have simulated the hop-parameter chaotic synchronization and its secure communication. Finally, the counteraction between the hop-parameter chaotic communication system and the wiretapping system is discussed. The simulation shows the hop-parameter chaotic synchronization and its secure communication have the virtue of easy realization and good security.
The variation of X-ray absorption spectra intensity caused by external magnetic field in drain current mode
Authors: Guo Yu-Xian  , Wang Jie  , Li Hong-Hong  , Xu Peng-Shou  , Wang Feng  , Yan Wen-Sheng  ,   中国科学技术大学国家同步辐射实验室，合肥  230029
Published: December 2020

In the measurement of X-ray magnetic circular dichroism (XMCD) spectra, external magnetic field is required during experiment. We have found that, if the X-ray absorption spectra are recorded using drain current, the spectrum intensity is strongly influenced by external magnetic field. The normalized signal intensity changes with the value of the deviation angle between magnetic field and sample surface, the amount of the external magnetic field and the relative position of beam spot on sample surface. In this paper, the K edge absorption spectra of oxygen contained in aluminum foil are measured in different magnetic field configurations. The variation trends of signal intensity with the change in various external parameters are indicated, and reasonable explanations have been given. The experimental data are well accordance with their corresponding fitting curves, suggesting that the model constructed in this paper is applicable for solving this problem. The article provides a basis for analyzing the effects of external field on drain current signal.
Mechanism and characteristics of the new organic nonlinear optical material urea L-malic acid film
Authors: Zhu Li  , Yang Wen-Ge  , Xu Ling-Ling  , Chen Ding-An  , Wang Wen  , Cui Yi-Ping  ,   (1)东南大学先进光子学中心，南京  210096; (2)南京工业大学材料科学与工程学院，南京  210009; (3)南京工业大学制药与生命科学学院，南京  210009
Published: December 2020

A new nonlinear optical material urea L-malic acid film (ULMA) was successfully prepared by physical vapour deposition (PVD) at appropriate heating temperature. XRD and FTIR measurements show that the film and the ULMA powder have the same composition and crystal structure. Furthermore, the film keeps the nonlinear properties of the ULMA crystal. Thermal analysis shows that ULMA has good thermal stability with constant melting point. Its evaporation temperature is below the decomposition temperature of its substrates urea and L-malic acid. The difference between evaporation and decomposition temperature is increased in vacuum. Therefore, it is verified that the PVD method is a practical approach to prepare ULMA film if the heating temperature is controlled between the evaporation and decomposition temperatures.
The interaction between solitons and chaotic behaviours of (2+1)-dimensional Boiti-Leon-Pempinelli system
Authors: Ma Song-Hua  , Qiang Ji-Ye  , Fang Jian-Ping  ,   浙江丽水学院物理系，丽水  323000
Published: December 2020

By an improved mapping approach, a series of excitations of the (2+1)-dimensional Boiti-Leon-Pempinelli system (BLP) is derived. Based on the derived solitary wave excitation, we obtain some special chaotic solitons and the interaction between solitons.
Constructing the exact solutions of the (2+1)-dimensional Hybrid-Lattice and discrete mKdV equation
Authors: Taogetusang  , Sirendaoerji  ,   内蒙古师范大学数学科学学院，呼和浩特  010022
Published: December 2020

The paper gives a method for combining the auxiliary equation with hyperbolic function by function transition. And then the method is applied to construct the new solitary wave solutions and the trigonomical function wave solutions to the (2+1)-dimensional Hybrid-Lattice and discrete mKdV equation with the help of the symbolic computation system Mathematica.
Differential variational principles of mechanical systems in the event space
Authors: Zhang Yi  ,   苏州科技学院土木工程系，苏州  215011
Published: December 2020

In this paper, the differential variational principles of mechanical systems in the event space are studied. The D'Alembert-Lagrange principle, the Jourdain principle, the Gauss principle and the universal D'Alembert principle in the event space are established on the basis of the D'Alembert principle of the system. The parametric forms of Euler-Lagrange, Nielsen and Appell for these principles are given, and the parametric form of Mangeron-Deleanu for the universal D'Alembert principle is deduced.
Local support vector machine prediction of spatiotemporal chaotic time series
Authors: Zhang Jia-Shu  , Dang Jian-Liang  , Li Heng-Chao  ,   西南交通大学信号与信息处理四川省重点实验室，成都  610031
Published: December 2020

In this paper, local support vector machine (LSVM)， which combins the advantage of traditional local prediction methods and support vector machines， is proposed to make local predictions of spatiotemporal time series. The LSVM is also used to discuss the selection of embedding dimension and the number of nearest neighbours, the coupling-way and the coupling coefficients of spatiotemporal chaotic systems that influence on the local predictions of spatiotemporal chaotic time series. Experimental results show that the LSVM can not only make better predictions of spatiotemporal chaotic time series than that of local zero-order methods and local linear methods and global support vector machine, but the computational complexity can also be reduced greatly compared to the global support vector machine. Moreover, the LSVM is insensitive to the selection of embedding dimension and the number of nearest neighbours. In addition, the local prediction performance of spatiotemporal chaotic time series is influenced by the coupling-way and the coupling coefficients of spatiotemporal chaotic systems.
Parabolic linear bound potential quantum dot qubit and its optical phonon effect
Authors: Wang Zi-Wu  , Xiao Jing-Lin  ,   内蒙古民族大学物理与机电学院，通辽  028043
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 Peakar 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 time evolution of the electron density. It is shown that the period of oscillation decreases with the strength of coupling increasing when the confined length is constant. And the period of oscillation increases with the confined length increasing when the strength coupling is constant.
The role of neuron transfer function in artificial neural networks
Authors: Wang Rui-Min  , Zhao Hong  ,   (1)兰州大学物理系，兰州  730000; (2)厦门大学物理系，厦门  361005
Published: December 2020

By analysis of local field distribution of the neurons in stationary state of associative memory neural networks, the role of the analog neuron transfer function in affecting the neural network performance is re-investigated. Different from the research done before, we find that the analog transfer function has no obvious advantages over the hard limit transfer function. Furthermore, analog transfer function sometimes produces a negative impact on certain functions of the network, such as the maximal storage capacity. We show that in pursuing the same performance a proper design rule is more essential than the choice of the transfer function.
The influence of the length and the velocy of vehicles on the mixed traffic flow in one-lane highway
Authors: Xiao Rui-Jie  , Kong Ling-Jiang  , Liu Mu-Ren  ,   广西师范大学物理与电子工程学院，桂林  541004
Published: December 2020

Based on NaSch traffic flow model, the mixed traffic flow model of whicles with different length and different maximum velocitdes on one-lane highway is proposed. Under periodic boundary condition, the influence of the length and the velocity of vehicles on the mixed traffic flow is studied by computer simulation.
The influence of nuclear orientation in fusion dynamics
Authors: Jia Fei  , Xu Hu-Shan  , Chen Ruo-Fu  , Zhang Hong-Bin  , Nasirov Avazbek  , Li Jun-Qing  , W. Scheid  ,   (1)Bogoliubov Laboratory of Theoretical Physics,JINR,Dubna  141980,Russia; (2)Institute for Theoretical Physics of Justus-Liebig-University,Giessen  35392,Germany; (3)中国科学院近代物理研究所，兰州  730000; (4)中国科学院近代物理研究所，兰州  730000；中国科学院研究生院，北京  100049
Published: December 2020

Fusion barriers have been calculated for different orientations of the axial symmetry axis of deformed projectile-and target-nucleus. Using the concept of dinuclear system, considering the strong competition between fusion and quasifission processes, by solving the master equation numerically to calculate the fusion probability of superheavy nuclei, we have estimated the dependence of the fusion probabilities for 76Ge+208Pb and 48Ca+244Pu on the orientation angles of the symmetry axis of projectile-and target-nucleus, which shows that belly-belly is the most favorable orientation for synthesizing superheavy nuclei.
The enhancement of efficiency of high-order harmonic generation in two-color laser field
Authors: Zhang Chun-Li  , Qi Yue-Ying  , Liu Xue-Shen  , Ding Pei-Zhu  ,   (1)吉林大学原子与分子物理研究所，长春  130012; (2)吉林大学原子与分子物理研究所，长春  130012；嘉兴学院机电工程学院，嘉兴  314001
Published: December 2020

We solve the time-dependent Schr?dinger equation in two-color laser fields by using asymptotic boundary condition and symplectic algorithm. The P?schl-Teller potential model with three bound states was considered in the numerical calculation. The population of ionization, average distance, HHG and the population of transition were calculated. We show that the efficiency of high-order harmonic generation (HHG) in two-color laser field can be enhanced, and analyze the mechanism of the enhancement of HHG. We demonstrate qualitatively the enhancement of conversion efficiency of HHG by the transition probability.
Theoretical analysis of cross-phase modulational sideband instability in wavelength-division multiplexed system with periodic dispersion managed fiber links
Authors: Li Qi-Liang  , Sun Li-Li  , Chen Jun-Lang  , Li Qing-Shan  , Tang Xiang-Hong  , Qian Sheng  , Lin Li-Bin  ,   (1)杭州电子科技大学通信工程学院通信与系统研究所光纤通信实验室，杭州  310018; (2)四川大学物理科学与技术学院，成都  610064
Published: December 2020

Dispersion management is a technology that alternately and periodically uses fibers with opposite dispersion sign in wavelength-division multiplexing link, thus the path averaged dispersion coefficient over each period is close to zero. This paper studies the cross-phase modulational sideband instability in chain of periodic dispersion managed and lumped amplified fiber link. Analytisis and numerical simulation are applied to show that there are multi-sidebands in the dispersion managed fiber link if the path averaged dispersion exhibits the abnormal dispersion, while there is only the lowest order if the path averaged dispersion exhibits the normal dispersion. The results of analytical and numerical simulation methods are consistent.
A new method for spectrum reproduction and interferogram processing
Authors: Jian Xiao-Hua  , Zhang Chun-Min  , Zhao Bao-Chang  ,   (1)西安交通大学理学院，西安  710049; (2)中国科学院西安光学精密机械研究所空间光学实验室，西安  710048
Published: December 2020

On the basis of researchon the theory and mathe matics of interference data collection of the spatially modulated polarization interference imaging spectrometer designed by us, this paper mainly analyses and compares three different methods of spectrum reconstruction and interferogram processing. Specially, the authors introduce the nonparametric model of Music algorithm which is maturely used in power spectrum estimation into the spectrum reconstruction processing for the first time. This method prodigiously improves the resolution of reproduced spectrum, and provides a better math matic model for the improvement of resolving power in spectrum reproduction.
Modulation response analysis of 1.3 μm quantum dot vertical-cavity surface-emitting lasers
Authors: Peng Hong-Ling  , Han Qin  , Yang Xiao-Hong  , Niu Zhi-Chuan  ,   中国科学院半导体研究所，北京  100083
Published: December 2020

Some important parameters, such as gain, 3 dB bandwidth and threshold current of 1.3 μm quantum dot vertical-cavity surface-emitting laser (QD VCSEL) are theoretically investigated. Some methods are developed to improve the VCSEL's modulation response. Significant improvement are prediced for p-type modulation doping. In connection with the threshold characteristic, we found that a structure with short cavity, multilayer quantum dots stack, p-type modulation doping and double intracavity contact on an un-doped DBR is much better suited to high speed quantum dot VCSELs. The parasitic effects of the VCSEL are analyzed and the influence of packaging of the VCSEL on its modulation responds is analyzed.
Perpendicular all-optical control of optical spatial soliton in photoisomerized polymers
Authors: Li Yang-Gang  , She Wei-Long  ,   中山大学光电材料与技术国家重点实验室，广州  510275
Published: December 2020

In the photoisomerized polymer，the perpendicular and all-optical control of optical spatial soliton is simulated by numerical method.The results show that if the controlling beam　(c-beam) and the signal beam (s-beam) are coherent, the s-beam under controll of the c-beam will be dispersed, deflected or even collapse. The interactions depend on the difference of the two beam's initial phases，c-beam's intensity and the incident position of c-beam. The effect of perpendicular and all optical control has potential applieations in all-optical switching and optical integration.
Nonfeedback control of Chen’s chaotic system
Authors: Chen Long  , Wang De-Shi  ,   海军工程大学兵器工程系，武汉  430033
Published: December 2020

Nonfeedback chaos control of Chen's chaotic system is realized with nonresonant parametric drive. The control input is a periodic signal whose frequency is far higher than the system characteristic frequency. The feasibility of this scheme is proved by averaging method and Lyapunov method, and the condition of control parameter is obtained. Numerical researches show that the controlled system can reach stable state rapidly even when the control signal is noisy.
Fabrication of photonic crystal on semiconductor materials by using focued ion-beam
Authors: Xu Xing-Sheng  , Xiong Zhi-Gang  , Jin Ai-Zi  , Chen Hong-Da  , Zhang Dao-Zhong  ,   (1)中国科学院半导体研究所光电子集成国家重点实验室，北京  100083; (2)中国科学院物理研究所，北京  100080
Published: December 2020

A method of manufacturing two-dimensional photonic crystals on several kinds of semiconductor materials in near infrared region by a focused ion beam is introduced, and the corresponding fabrication results are presented and show that the obtained parameters of fabricated photonic crystals are identical with the designed ones. Using the tunable laser source, the spectra of the fabricated passive photonic crystal and the active photonic crystal are measured. The experiment demonstrates that the focused ion-beam can be used to fabricate the perfect two-dimensional photonic crystals and their devices.
Research on the formation of narrow bandwidth long flat-top pulse via coherent addition of ultra-short pulses
Authors: Ma Zai-Ru  , Feng Guo-Ying  , Chen Jian-Guo  , Zhu Qi-Hua  , Zeng Xiao-Ming  , Liu Wen-Bing  , Zhou Shou-Huan  ,   (1)四川大学电子信息学院光电系,成都   610064; (2)四川大学电子信息学院光电系,成都   610064；华北光电技术研究所，北京  100015; (3)中国工程物理研究院激光聚变研究中心，绵阳   621900
Published: December 2020

Making use of the spectrum gain narrowing effect during the ultra-short pulse amplification in the gain media and the filter effect of the etalon, and adopting the principles of the regenerative amplifier, the multi-pulse coherent addition scheme is proposed and analyzed. In the small signal gain region of the ultra-short pulse amplification in the regenerative amplifier, theoretical analysis and numerical simulation have been made on the multi-pulse coherent addition stage. The simulation suggests that the width of the sub-pulse, the loss in the regenerative amplifier and the mismatch between the oscillator and the regenerative amplifier are the key factors affecting the temporal shape of the composite pulse, although they have little influence on its spectrum. Both the numbers of the constituent sub-pulses and the bandwidth of the etalon have influence on the shape and spectrum of the pulse.
A all-optical switching based on highly nolinear photonic crystal fiber Sagnac loop mirror
Authors: Liu Jian-Guo  , Kai Gui-Yun  , Xue Li-Fang  , Zhang Chun-Shu  , Liu Yan-Ge  , Wang Zhi  , Guo Hong-Lei  , Li Yan  , Sun Ting-Ting  , Yuan Shu-Zhong  , Dong Xiao-Yi  ,   南开大学现代光学研究所，天津  300071
Published: December 2020

We designed a novel and low switching-power all-optical fiber switch. The highly nonlinear photonic crystal fiber and the bi-directional pumped Er-doped fiber amplifier are inserted into the Sagnac loop mirror simultaneously. The switching is realized based on cross-phase modulation because the symmetry of the loop is broken. The theoretical analysis shows that the switching-power is inverse proportional to the product of the amplifier gain and the nonlinear coefficient of the photonic crystal fiber. In our experiment, 40 mW switching-power and 15.9 dB switching-extinction are obtained; furthermore, the transmission of signal light is a cosine function of the peak power of the control pulse. All the results of experiment well agree with the theory.
Performance analysis of control pulse in optical controlled apparatus based on semiconductor optical amplifier
Authors: Li Ya-Jie  , Wu Chong-Qing  , Wang Yong-Jun  , Tang Qing-Shan  ,   (1)北京交通大学理学院光信息科学与技术研究所，北京  100044; (2)中国科学院声学研究所，北京  100080
Published: December 2020

On the basis of optical resilient packet ring (O-RPR), this paper analyzes the control optical power needed for dual loop optical buffer (DLOB) to achieves ‘write-read’ successfully, and discusses the influencing factors on this power. Then we discuss the pulse compression and chirp caused by the signal pulse not being ideally square, and analyze the influence of power fluctuation and signal-to-noise ratio(SNR) of control light on output data.
Erbium-doped hole-assisted lightguide fiber: structural study and optimization
Authors: Zheng Kai  , Chang De-Yuan  , Fu Yong-Jun  , Wei Huai  , Yan Feng-Ping  , Jian Wei  , Jian Shui-Sheng  ,   北京交通大学光波技术研究所,北京  100044
Published: December 2020

Erbium-doped hole-assisted lightguide fiber (EDHALF) is composed of a high-index core doped with erbium, a low index cladding and a small number of air holes surrounding the core. The finite element method is applied for solving the modal field of the EDHALF. The numerical calculation methods of the cutoff wavelength and mode field diameter are described in detail. The modified average population inversion iteration method is proposed for calculating the gain and noise figure of erbium-doped fiber amplifiers. The effects of the air holes on EDHALFs' cutoff wavelengths, mode field diameters and the gain coefficients of fiber amplifiers are studied. It's found that decreasing the relative hole-to-core spacing can make the cutoff wavelength move to shorter wavelength and decrease the mode field diameter. When the relative size of air holes is relatively large, further enlarging it only slightly changes the cutoff wavelength, mode field diameter and the maximum of the gain coefficient. Finally, four structural parameters, namely the EDHALF-core radius, the refractive index difference between the core and cladding, the relative hole-to-core spacing and the relative size of air holes are optimized in terms of the design criteria, which take into account the cutoff wavelengths of fundamental mode and the second order mode, the gain and noise figure of fiber amplifiers and the splice loss between the EDHALF and the conventional single-mode fiber.
Phase constitution and solidification characteristics of undercooled Ag-Cu-Ge ternary eutectic alloy
Authors: Mei Ce-Xiang  , Ruan Ying  , Dai Fu-Ping  , Wei Bing-Bo  ,   西北工业大学应用物理系,西安  710072
Published: December 2020

Liquid Ag38.5Cu33.4Ge28.1 ternary eutectic alloy was undercooled by a great degree up to 175 K(0.22 TE). X-ray diffraction analysis reveals that its rapidly solidified microstructure is composed of (Ag) solid solution phase, (Ge) semiconducting phase and η(Cu3Ge) intermetallic compound phase. With the increase of undercooling, there occurs a transition from the cooperative growth of three eutectic phases to the preferential nucleation and growth of (Ge) phase. The (Ag) and η phases usually grow to form pseudobinary lamellar eutectic structure. When the undercooling exceeds 80 K, the structural morphology of primary (Ge) phase transfers from faceted blocks to branched dendrites. Some (Ge) dendrites look like flowers, which usually have 5—8 lobes. In addition, the number of lobes tends to increase as undercooling increases. The crystal surfaces of the flower-like (Ge) dendrite are {111} planes and the dendrite grows along the 〈100〉 preferred growth direction.
First-principles study of electronic structure for Cd-doped wurtzite ZnO
Authors: Tang Xin  , Lü Hai-Feng  , Ma Chun-Yu  , Zhao Ji-Jun  , Zhang Qing-Yu  ,   (1)大连理工大学高科技研究院,大连  116024; (2)大连理工大学三束材料改性国家重点实验室,大连  116024; (3)中国科学院计算机网络信息中心超级计算中心,北京  100080
Published: December 2020

Using the density-functional theory (DFT) combined with the projector augumented wave (PAW) method, we have investigated the electronic structure of Cd-doped wurtzite ZnO. Analysis of the band structures, density of states (DOS) and partial density of states (PDOS) of CdxZn1-xO shows that the valence band maximum (VBM) is determined by O-2p states and the conduction band minimum (CBM) is occupied by the hybrid Cd-5s and Zn-4s orbital. The energy of CBM decreases and the energy of VBM increases with increasing Cd-doped concentrations. Both effects lead to narrowing of the band gap. Furthermore, it was found that Cd-doped can cause tensile strain in the crystal structure, which also reduces the band gap.
Approimate solution for three dimentional equatorial sea-air oscillator model
Authors: Mo Jia-Qi  , Lin Wan-Tao  ,   (1)LASG,中国科学院大气物理研究所,北京  100029; (2)安徽师范大学,芜湖  241000；湖州师范学院,湖州  313000；上海高校计算科学院E-研究院上海交通大学研究所,上海  200240
Published: December 2020

An equation for the equatoral Kelvin wave is considered. By using the variational iteration method, the approximate solution is studied. The variational iteration method is an analytic method, the obtained solution can be analytic operation sequentially.
Time-dependent perturbation theory of KdV soliton
Authors: Pan Liu-Xian  , Yu Hui-You  , Yan Jia-Ren  ,   (1)湖南师范大学物理系，长沙  410081; (2)湖南师范大学物理系，长沙  410081；湖南涉外经济学院电子与信息工程系，长沙  410205
Published: December 2020

The effects of the periodical time-dependent perturbation on a KdV (Korteweg de Vries) soliton are studied. Expanding the perturbation term into a Fourier series, we find that the time-independent term will lead to the secular terms. In this paper, the soliton parameters (height, width and velocity) are derived by eliminating the secular terms, and the corrections on a soliton caused by perturbation are obtained with the help of other terms in Fourier series in the first-order approximation.
Recurrence spectra and closed orbits of He+2 in parallel electric and magnetic fields
Authors: Wang Xiao-Yan  , Wang Peng-Cheng  , Feng Sheng_Ping  , Xie Jin_Dong  ,   泰山医学院放射学院，泰安  271016
Published: December 2020

By the semi-classical closed orbit theory and region-splitting consistent iteration method, we calculated the recurrence spectra and closed orbits of He+2 in parallel electric and magnetic fields. Using the new potential with electronic exchange interaction, complex channel quantum defects and molecular closed orbits theory, we discussed the influence of molecular core to the recurrence spectra and closed orbits.
Studies on vibrational excitation differential cross sections of low-energy electron scattering from N2 molecule by vibrational close-coupling method
Authors: Dai Wei  , Feng Hao  , Sun Wei-Guo  , Tang Yong-Jian  , Shen Li  , Yu Jiang-Zhou  ,   (1)四川大学物理科学与技术学院,成都  610065; (2)四川大学原子与分子物理研究所,成都  610065; (3)四川大学原子与分子物理研究所,成都  610065；中国工程物理研究院激光聚变研究中心,绵阳  621900; (4)中国工程物理研究院激光聚变研究中心,绵阳  621900
Published: December 2020

The differential cross sections (DCS) of low-energy electron-N2 scattering are studied using vibrational close-coupling (VCC) method and vibrational scattering potentials which include the static, exchange and polarization contributions, where the polarization is obtained on the basis of “better than adiabatic dipole" (BTAD) and “distributed spherical Gaussian" (DSG) respectively. The converged (0→2, 0→3) DCS are obtained for the impact energy of 2.40eV. Calculations using both polarization potentials agree with experimental results. The physical factors that possibly affect the accuracy of DCS values are also discussed.
Adaptive control of uncertain chaotic systems with time delays using dynamic structure neural network
Authors: Zhang Min  , Hu Shou-Song  ,   南京航空航天大学自动化学院,南京  210016
Published: December 2020

A kind of control methods is surveyed to deal with a class of nonlinear systems with uncertain time delay. By combining the Lyapunov-Krasovskii function and Lyapunov function, the time-delay compensator with adjustable parameters is presented to make the control input independent of the multiple time delays. At the same time, the dynamic structure adaptive neural network is introduced to eliminate the uncertainties in the chaotic system, which approximates the function with better relationship between the calculation rate and structure complexity by increasing hidden units when the tracking error is beyond the allowable bound. The demonstration with a given Duffing chaotic system shows the presented control method is effective.
Breaking a chaotic direct sequence spreading spectrum secure communication system
Authors: Hu Jin-Feng  , Guo Jing-Bo  ,   清华大学电机系,电力系统国家重点实验室，北京  100084
Published: December 2020

In this paper, a novel method is proposed for the breaking of chaotic direct sequence spread spectrum (CD3S) secure communication system. Chaotic fitting is defined based on the concept of generalized synchronization, then the method based on unscented Kalman filter and chaotic fitting is presented based on the principle of CD3S and the characteristic that the information symbol varies slowly. Furthermore, addressing to the tracking error induced by the processing noise and chaotic fitting error, a modified unscented Kalman filter based on tracking-error-controlled factor is suggested. The CD3S is unmasked according to the error-amplitude of the tracking-error. We can extract the binary message signal from the CD3S signal without knowing either the structure or the parameters of the chaotic transmitter. Simulation results verify the method.
Regular and chaotic motions of a single Paul-trapped ion interacting with double-δ-kicked pulses
Authors: Chen Wen-Qin  , Hai Wen-Hua  , Song Jian-Wen  ,   (1)湖南师范大学物理系,长沙  410081; (2)湖南师范大学物理系,长沙  410081;华南热带农业大学基础学院，儋州  571737
Published: December 2020

We investigate the regular and chaotic motions of a single Paul-trapped ion under the pseudopotential approximation, which interacts with a double-δ-kicked periodic potential. We apply the method of integral-equation to construct the exact solution of the classical equation and use the numerical technique to plot the orbits in phase space and the time evolutions of average energies. Combining the analytical results with the numerical ones, we arrived at two interesting conclusions: Firstly, there are regular stable motions of the double δ-kicked system,at variance with the resonance case of the corresponding single δ-Kicked system. Secondly, when the time interval between the double δ pulses becomes shorter, the regular motion of the system becomes chaotic, and the speed of classical diffusion of the average energy is related to the degree of chaos. It is shown that the resonance may lead to loss of stability and the instability can be controlled by adjusting the laser wave vector.
Experimental and theoretical investigation of fused silica rod-fiber phase conjugator
Authors: Wang Sha  , Chen Jun  , Tong Li-Xin  , Gao Qing-Song  , Liu Chong  , Tang Chun  ,   (1)浙江大学光学仪器国家重点实验室，杭州  310027; (2)中国工程物理研究院应用电子学研究所，绵阳  621900
Published: December 2020

A novel combined phase conjugator consisting of a fused silica rod and silica fiber is used in the high repetition laser system to improve the light quality. It has the advantages of higher stimulated Brillouin scattering reflectivity, higher stimulated Brillouin scattering damage threshold and lower stimulated Brillouin scattering threshold. In experiment, under the repetition rate of 100 Hz, maximum 42.05% stimulated Brillouin scattering reflectivity is obtained. According to the coupling wave equations and the boundary conditions of the experiment, the numerical value calculated from this model is in accordance with the experiment result. And the way to improve the working state of this combined phase conjugator is brought forward by our modeling.
Study on point-to-point mobile underwater acoustic communication
Authors: Yin Jing-Wei  , Hui Jun-Ying  , Guo Long-Xiang  ,   哈尔滨工程大学水声工程学院，哈尔滨  150001
Published: December 2020

Point-to-point mobile underwater acoustic (UWA) communication is one of the key technologies for UWA networks which consists of mobile and stationary nodes. The mobile communication UWA channels are analyzed, whose eigen rays have different Doppler shifts which enhances the complexity of intersymbol interference (ISI) caused by the multipath channel, that goes against the UWA communication. The channel equalization using single sensor passive phase conjugation mirror (PPCM) is proposed to compensate for the Doppler shift in real time and to focus the multipath signals. The application of single sensor PPC to communication system based on Pattern time delay shift coding scheme is carried out in lake trials. The results of lake trials validated the capability of PPCM mitigating ISI and the robustness of the communication system.
Growth and electrical conductivity of Gd2O3 doped CeO2 ion conductor electrolyte film on sapphire substrate
Authors: Jiang Xue-Ning  , Wang Hao  , Ma Xiao-Ye  , Meng Xian_Qin  , 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

Nanocrystalline Gd2O3 doped CeO2 (abbreviated as GDC) ion conductor electrolyte thin films synthesized by reactive magnetron sputtering on (0001) sapphire substrates have been characterized by X-ray diffraction (XRD)，atomic force microscopy (AFM) and AC impedance analysis. The results show that，the f.c.c structured GDC films have strong (111) textures at all the substrate temperatures of our investigation while the surface morphology varied with the temperature. Small, round growth islands transform to large prismatic islands at temperatures from room temperature to 300℃, and the reverse process occurr at temperatures from 400℃ to 700℃. This morphology change characterizing different nucleation mechanisms at the beginning of film growth is probably due to transformation of the surface structure of the (0001) sapphire at different temperatures. The AC impedance complex plane plot of the GDC film is mainly determined by grain boundary resistances. The conductivity activation energy (1.2—1.5eV) calculated by the Arrhenius plot is close to the reported value for the grain boundary conductivity and decreases with rising substrate temperature (Ea300Ea400Ea600). Difference in activation energy and grain size for GDC films causes unequal increasing rates of electrical conductivity at higher temperatures.
Peierls phase transition and field emission of carbon nanotubes in a magnetic field
Authors: Sun Hai-Jun  , Liang Shi-Dong  ,   中山大学物理科学与工程技术学院，广州  510275
Published: December 2020

Using the tight-binding approach with the WKB method，we study the Peierls phase transition of the single-wall carbon nanotube and the field emission in a magnetic field along the tube axis. We find that the Peierls phase transition may occur above room temperature，which induces an energy gap near the Fermi level，leading to the metal-semiconducting phase transition of the carbon nanotubes. The Peierls distortion of the carbon nanotubes suppresses the field emission current. The Peierls distortion may be modified by the magnetic field applied along the tube axis. The energy band structure of the carbon nanotubes depends on the competition between the Peierls distortion and the magnetic field effect，which affects the field emission current of the carbon nanotubes.
Fabrication and optical properties of 2D ordered arrays of CdS nanocrystals by nanosphere lithography
Authors: Sun Ping  , Xu Ling  , Zhao Wei-Ming  , Li Wei  , Xu Jun  , Ma Zhong-Yuan  , Wu Liang-Cai  , Huang Xin-Fan  , Chen Kun-Ji  ,   (1)南京大学物理系，固体微结构国家重点实验室，南京  210093; (2)上海微系统和技术信息研究所，上海  200050
Published: December 2020

We realized the fabrication of 2D ordered arrays of CdS nanocrystals by nanosphere lithography by use of a monolayer of self-assembled polystyrene spheres 220nm in diameter as a mask. We used scanning electron microscope (SEM) to characterize the structure of samples. The results indicate that the 2D arrays of CdS nanocrystals produced by nanosphere lithography have highly ordered structure which has the same period of the original PS mask. According to the transmission spectrum，it is estimated that the forbidden band width of the CdS nanocrystals is around 2.60eV，which shows a size-dependence of the CdS nanocrystals. This structure has the promising application in the light filter and single-photon emitter.
High-speed data format conversion from non-return-to-zero to return-to-zero based on periodically poled lithium niobate waveguides
Authors: Wang Da-Lin  , Sun Jun-Qiang  , Wang Jian  ,   武汉光电国家实验室，华中科技大学光电子科学与工程学院，武汉  430074
Published: December 2020

Based on the cascaded second-order nonlinear interactions in a periodically poled lithium niobate waveguide, a novel scheme of all-optical data format conversion from non-return-to-zero to return-to-zero is proposed, using a Mach-Zehnder interferometer structure. The conversion mechanism relies on the amplification effect induced on the signal field via cascaded second-harmonic generation and difference-frequency generation, which makes the Mach-Zehnder interferometer unbalanced and leads to the output of return-to-zero due to destructive interference. Firstly, the non-return-to-zero to return-to-zero conversion process is numerically simulated based on the coupled-wave equations. Secondly, the dependence of the extinction ratio on the waveguide length, optical power, and time-delay is analyzed and optimized. Finally, the conversion bandwidth is also discussed. It is found that the signal wavelength can be tuned in a wide wavelength range of approximately 90nm, thus simultaneous multi-channel non-return-to-zero to return-to-zero data format conversion can potentially be implemented with the proposed scheme.
Numerical simulation of nonlinear mechanical behaviour of single-walled carbon nanotubes
Authors: Yao Xiao-Hu  , Han Qiang  , Xin Hao  ,   华南理工大学交通学院工程力学系，广州  510640
Published: December 2020

The mechanical behavior of single-walled carbon nanotubes (SCWNTs) is one of the basic properties of the nanotube composite and nano machinery. The axial and bending buckling behavior of SWCNTs is systematically investigated by finite element mothod(FEM) in this paper. The results of molecular dynamics and FEM simulations are compared. Simulation results show that the axial buckling loads are dependent strongly on the diameter, and the buckling and postbuckling behavior of SWCNTs under bending depends strongly on the length and radii of the tube. With appropriate choice of Young's modulus and tube thickness, the FEM simulation provides some useful insight into the buckling mechanism of carbon nanotubes. The finite element method turns out to be a new, forthright and precise method for the simulation in solving large-scale nano-mechanics problems.
Formation and structure transition of gold nanoparticles on surface of carbon nanotube
Authors: Li Jun  , Zhang Kai-Wang  , Meng Li-Jun  , Liu Wen-Liang  , Zhong Jian-Xin  ,   湘潭大学材料与光电物理学院,湘潭  411105
Published: December 2020

Formation and structure of gold nanoparticles at room temperature on the surface of carbon nanotube have been studied by molecular dynamics simulation.It was shown that，different from isolated gold nanoparticles，a gold nanoparticle AuN sitting on the surface of carbon nanotube undergoes a structural transition.Small gold nanoparticles with N≤130 have disordered structures while larger particles with N≥140 have the face centered cubic structure of bulk crystalline gold.The binding energy per atom of AuN decreases as its size decreases.It was also shown that the strength of the interaction between a small gold nanoparticle and the carbon nanotube is proportional to their contact surface area，indicating a close contact between the two structures.
Research on spectral-properties of nonpolar ZnO film on γ-LiAlO2
Authors: Zhou Jian-Hua  , Zhou Sheng-Ming  , Huang Tao-Hua  , Lin Hui  , Li Shu-Zhi  , Zou Jun  , Wang Jun  , Han Ping  , Zhang Rong  ,   (1)南京大学物理系，南京  210093; (2)中国科学院上海光学精密机械研究所，上海  201800; (3)中国科学院上海光学精密机械研究所，上海  201800；中国科学院研究生院，北京  100049
Published: December 2020

Nonpolar a-plane ZnO film was successfully grown on (302)γ-LiAlO2 substrate by pulsed laser deposition. The temperature of substrate was 500℃, the film was pure nonpolar a-plane ZnO. The FWHM of the peak of near band emission in the PL spectrum was found to be only 115 meV. Both polarized transmission spectra and polarized Raman spectra revealed the in-plane anisotropy of the nonpolar ZnO film by the shift of absorption edge and the change of intensity of Raman E2 mode.
Abnormal transport behavior in the mult-spin Co-doped La2/3Ca1/3MnO3 manganites
Authors: Yu Qian-Ying  , Zhang Jin-Cang  , Jia Rong-Rong  , Jing Chao  , Cao Shi-Xun  ,   上海大学物理系，上海  200444
Published: December 2020

The spin structure and polarization characters are the dominant aspects in the physical properties of manganite systems with colossal magnetoresistance effect. In this paper, a series of Mn-site doping samples La2/3Ca1/3Mn1-xCoxO3 (0≤x≤0.15) have been prepared with Co ion which has mult-spin states. The structure and transport properties of this system have been systematically investigated. The results showed that all the samples show good single phase and the lattice parameters decrease with the increasing of doping concentration x. The abnormal transport properties are induced by Co doping. To be specific, the resistivity exhibits two metal_insulator (M—I) transitions (double peak effect). Both high temperature peak (TMIH) and low temperature peaks (TMIL) shift to low temperature end with increasing x. While the TMIH shifts to high temperature, the TMIL is almost unchanged under the external field. The corresponding peak values of resistivity show strong dependence on the external field and Co doping concentration x. All the peak values of resistivity increase with the increase of x, and the low temperature peak value seems more sensitive than the high temperature peak. Compared with the magnetization properties, it could be concluded that, the high temperature peak is related with the undoped M-I transition, and the abnormal behavior of low temperature peak has certain relationship with the oxygen vacancy and high spin state induced by Co3+ substituting Mn4+ in the present system.
The power dissipation of equivalent series resistance and its influence on lumen efficiency of GaN based high power light-emitting diodes
Authors: Li Bing-Qian  , Liu Yu-Hua  , Feng Yu-Chun  ,   (1)佛山科学技术学院光电子与物理学系，佛山  528000; (2)深圳大学光电子学研究所,广东省光电子器件与系统重点实验室,光电子器件与系统教育部重点实验室,深圳  518060
Published: December 2020

Because of the self-heating effect of InGaN based high power light-emitting diodes (LEDs), the temperature of the LED chip is much higher than the case temperature (TC). The maximum Tj in our experiment is 148K higher above the case temperature. The voltage drops on p-n junction and equivalent series resistance are extracted from the measured I-V curve, and then the values of equivalent series resistance at different forward power are obtained. Due to the self-heating effect, the values of equivalent series resistance show a very strong forward power-dependent characteristics, the maximum equivalent series resistance reported in this paper is about 1.9Ω at high forward power, being more than twice the minimum value. The power dissipation of equivalent series resistance is increased sharply when the forward power is increased, nearly half of the forward electrical power was dissipated on equivalent series resistance at high power, and it becomes the an important factor restraining the lumen efficiency of high power GaN based light emitting diodes.
Chaos anti-control of nonlinear system with uncertainties
Authors: Li Wen-Lin  , Song Yun-Zhong  ,   (1)河南理工大学电气工程与自动化学院复杂网络研究室，焦作  454000; (2)河南师范大学数学与信息学院，新乡  453007
Published: December 2020

The model for realizing chaos anti-control of nonlinear system is studied based on sliding mode variable structure control，and on account of which the identity of the controlled system model and chaos reference model is guaranteed in finite time. Both its speed and robustness are discussed theoretically. As an example，Lorenz chaotic system is employed as the chaos reference model for the simulation verification. Results show that the suggested method is valid.
“Black silicon" antireflection thin film prepared by electrochemical etching
Authors: Liu Guang-You  , Tan Xing-Wen  , Yao Jin-Cai  , Wang Zhen  , Xiong Zu-Hong  ,   西南大学物理科学与技术学院,重庆  400715
Published: December 2020

Solar cells and optical detection devices are often covered with antireflective surfaces to enhance their performance. An economical, fast, and easily operational electrochemical etching technique has been developed to realize a continuous uniform variation in the refractive index of porous silicon layer as a function of the etching depth. By using this technique a black silicon sample was fabricated, which has a reflectance below 5% over a broad band and a thickness below 1μm. The depression mechanism of the optical reflectance is analyzed by simulating the structure with the transfer matrix method. The simulated results give a good agreement with the experimental measurements.
Quantum phase transition as a result of magnetic frustrations in a ferrimagnetic Heisenberg system
Authors: Zhang Song-Jun  , Jiang Jian-Jun  , Liu Yong-Jun  ,   扬州大学物理科学与技术学院,扬州  225002
Published: December 2020

Using density-matrix renormalization group (DMRG) method, we studied the effect of magnetic frustrations due to next-nearest- neighbor bonds in a system of quasi-one-dimensional Heisenberg antiferromagnetic chain but with ferrimagnetic properties. In this paper, the ground state energy per unit cell, spin correlation function and spin gap are calculated. As a result of the frustrations, the quantum disordered phase with the spin gap appears at the spin order-disorder phase transition point αC≈0.412 to α＝1. And in the region of magnetic-order phase, the increasing magnetic frustrations reduce the magnetic order.