bluuebunny/crossref_metadata_2025 huggingface dataset:
Research of the recombination rate of space charge in LDPE film during the short-circuit discharge process via the photon counting method
Authors: Xiao Chun  , Zhang Ye-Wen  , Lin Jia-Qi  , Zheng Fei-Hu  , An Zhen-Lian  , Lei Qing-Quan  ,   (1)哈尔滨理工大学，哈尔滨  150080; (2)同济大学波耳固体物理研究所，上海  200092
Published: December 2020

In this paper，the recombination rate of charges in low density polyethylene （LDPE） film was obtained by measuring the number of photons released from the film when the film was short-circuit discharged after being set to high voltage of direct current （HVDC）. Under different designed conditions, including changing the polarity of HVDC and the value of applied field and the time duration of applied field，the amount of photons was measured to calculate the charges’ combination rate. The result showed that the measured number of photons （recombination rate） was sensitive to the applied field but insensitive to the applying duration. When the field was higher than 80 MV/m，the number of released photon increased slowly with increasing voltage. Using the date obtained in our experiment as well as those in other papers，the luminous efficiency of LDPE film was calculated to be 5.9×10-6，and the charges’ recombination rate during first 0.2 second at the beginning stage of short-circuit is around 2.8%.
Effect of oxygen on CdS polycrystalline thin films prepared in ambient of Ar and O2 by close spaced sublimation technology
Authors: Xia Geng-Pei  , Feng Liang-Huan  , Cai Ya-Ping  , Li Bing  , Zhang Jing-Quan  , Zheng Jia-Gui  , Lu Tie-Cheng  ,   (1)四川大学太阳能材料与器件研究所，成都  610064; (2)四川大学太阳能材料与器件研究所，成都  610064；四川大学物理系，辐射物理及技术教育部重点实验室，成都  610064
Published: December 2020

In this paper，CdS polycrystalline thin films were prepared with the close-spaced sublimation （CSS） technology. In the deposition process，a controlled ambient of Ar and O2 mixture was used. The effect of oxygen on the microstructure，composition，morphology as well as optical and electrical properties of CdS thin films were studied systemically by XRD，XPS，AFM，UV-VIS and four-probe array method. The results showed that the CSS-grown CdS thin film has the hexagonal structure with crystallite size about 40 nm and the composition of them were rich in S. The impurity oxygen atoms mixed into CdS thin films and partly formed CdO，and with the increase of O2 concentration the chemical composition tinds more closely to the ideal stoichiometric proportion of CdO，the optical gap of thin films broadened and the ratio of photoconductivity to darkconductivity increased. Fortunately these effects are benefitial to CdS thin films for the photovoltaic application as a window layer.Additionally，it view of CdS/CdTe interface，we investigated the influence of oxygen on the cross-section morphology of CdS/CdTe thin films and the spectral response （SR） of the device. Then the results indicated that with the increase of O2 concentration in deposition ambient，the interdiffusion between CdS and CdTe decreased，and the SR of device in the range from 500 nm to 600 nm increased.We believe that the oxygen in CSS-grown CdS thin films plays a very important role in two aspects，firstly in improving the quality of CdS thin films for photovoltaic application，secondly in optimizing the CdS/CdTe interfacial properties in the CdTe solar cells.
Grain size effect of charge ordering of Bi0.2Ca0.8MnO3
Authors: Li Xiao-Juan  , Wang Qiang  ,   (1)陕西教育学院数理工程系，西安  710061; (2)西安工业大学材料与化工学院，西安  710032
Published: December 2020

A series of Bi0.2Ca0.8MnO3 samples with average grain size ranging from 38 to 1500 nm have been prepared by the sol-gel method and their structure，electrical transport，and magnetic properties were investigated. It is found that with the reduction of the grain size，the charge ordered phase gradually diminishes till it is completely suppressed，leading to appearance of the spin-glass state at low temperature. These behaviors are discussed in terms of the martensitic transformation and surface effect.
Effect of H3BO3 on composition and luminescence properties of BaAl2Si2O8：Eu2+ blue phosphor
Authors: Ma Ming-Xing  , Zhu Da-Chuan  , Tu Ming-Jing  ,   四川大学材料科学与工程学院，成都  610065
Published: December 2020

The Eu2+ activated blue emitting BaAl2Si2O8：Eu2+ phosphor was synthesized by one-step calcination process of precursor prepared with chemical coprecipitation. X-ray diffraction （XRD），fluorescence spectrophotometry and scanning electron microscopy were used to investigate the structure，luminescent property and morphology of the BaAl2Si2O8：Eu2+ blue phosphor. The results showed that BaAl2Si2O8：Eu2+ phosphor synthesized by the process was pure. The crystal structure of BaAl2Si2O8 transformed from hexagonal structure to monoclinic structure after precursor doping H3BO3，which changed the emission peak and luminescence intensity of BaAl2Si2O8：Eu2+ phosphor. The luminescence intensity firstly increased with H3BO3 doping concentration increasing，then decreased. The optimum mass fraction of H3BO3 is about 1.5%. The use of H3BO3 as flux could help the phosphor to crystallize，thus enhance the intensities of the excitation and emission spectra of BaAl2Si2O8：Eu2+ phosphor，improve the morphology of particles，and endow them with round edges，smooth surfaces and nearly spherical shapes.
Synthesis and luminescenct properties of LaPO4：Dy phosphors with different morphology
Authors: Wu Chun-Fang  , Meng Xie  , Li Jie  , Wang Yu-Hua  ,   (1)兰州大学物理科学与技术学院，兰州  730000; (2)兰州大学物理科学与技术学院，兰州  730000；兰州大学磁学与磁性材料教育部重点实验室，兰州  730000
Published: December 2020

LaPO4：Dy phosphors with different morphology were prepared by adjusting phosphorus sources and reagent in hydrothermal reaction and their vacuum ultraviolet excited luminescence were investigated. The results show that the luminescent intensity of LaPO4：Dy phosphor varies for different morphologies and different particle size. The site symmetry of Dy3+ ions in the LaPO4：Dy phosphor with three different morphologies was consistent and the ratio of yellow emission to blue emission of the three phosphors was kept in 1 to 1.5. From the comparison of the excitation spectra of LaPO4：Dy and GdPO4：Eu it could been seen that the energy transfer efficiency from phosphate host to Dy3+ ion is lower than that to Eu3+ ion. Meanwhile stronger f-d transition was observed in the excitation spectra.
In-situ polymerization and properties of poly (2,5-dibutyloxy-1,4-phenylene vinylene)/multi-walled carbon nanotube composites
Authors: Sun Jian-Ping  , Weng Jia-Bao  , Huang Xiao-Zhu  , Ma Lin-Pu  ,   (1)福建师范大学化学与材料学院，福州  350007; (2)福建师范大学化学与材料学院，福州  350007；福建省高分子材料重点实验室，福州  350007
Published: December 2020

The photoelectric composites of poly （2，5-dibutyloxy-1，4-phenylene vinylene）/ multi-walled carbon nanotubes （PDBOPV/MWCNTs） were prepared by in-situ polymerization. The results of Fourier transform infrared spectroscopy and Raman spectroscopy indicate that PDBOPV is coated on the surface of MWCNTs. The dimensions of the composite were observed by high resolution transmission electron microscopy，the diameter of PDBOPV/MWCNTs was measured to be about 35—45 nm，and the thickness of the coated PDBOPV is about 15 nm. The absorption of PDBOPV/MWCNTs is strengthened with the contents of MWCNTs increasing，and a red shift of the absorption peak can be clearly observed in the UV-Vis spectrum. Photoluminescence spectroscopy indicates that the maximum emission wavelength of the PDBOPV/MWCNTs is blue-shifted and intensity of photoluminescence decreases with increasing MWCNTs concentration. PDBOPV/MWCNTs show fluorescence quenching，which involves the inter-molecular photo-induced charge transfer process. The optical band gap of PDBOPV/MWCNTs decreases gradually with the contents of MWCNTs increasing. Third-order optical nonlinear susceptibility of PDBOPV/MWCNT composites were measured by degenerate four wave mixing. The results showed that the third-order nonlinear optical responses of PDBOPV/MWCNT composites were enhanced gradually when MWCNT content increased，which can be attributed to inter-molecular photo-induced electron transfer and π-π electron coupling between PDBOPV and MWCNTs.
Optical filtering and angle-resolved tuning properties of the waveguided grating structures
Authors: Song Jiao-Yang  , Feng Sheng-Fei  , Zhang Xin-Ping  , Liu Hong-Mei  , Song Yan-Rong  ,   北京工业大学应用数理学院，北京  100124
Published: December 2020

Waveguided grating structures were fabricated using interference lithography. The angle resolved tuning properties of the resonant waveguide mode and its dependence on the grating parameters and on the polarization properties of the incident light were investigated. In particular, the influence of the grating period and waveguide thickness on the tuning rate of the resonance waveguide mode was charatcerized. Theoretical simulation showed good agreement with the experimental results, which is important for futher applications of the waveguided grating device in filters and sensors.
Preparation of poly-slicon thin film by aluminum induced crystallization based on Al-salt solution
Authors: Luo Chong  , Meng Zhi-Guo  , Wang Shuo  , Xiong Shao-Zhen  ,   南开大学光电子器件与技术研究所,天津  300071
Published: December 2020

A new method to prepare polycrystalline silicon thin film from a-Si thin films using aluminate solution as induced source was introduced in this article. According to the analysis using optical microscope and Raman spectrum, it was indicated that the a-Si thin film could successfully be crystallized in certain Al-salt solutions. Using the X-ray photoelectron spectroscopy explored by shelling the samples into several sub-layers, the possible chemical reaction between the surface of silicon and aluminate solution was found and the continuous layer exchange process was confirmed. In the end, the mechanism of solution-based aluminum-induced crystallization was discussed.
Slow drag in jammed granular medium
Authors: Peng Zheng  , Lu Kun-Quan  , Hou Mei-Ying  ,   (1)北京凝聚态物理国家实验室，中国科学院物理研究所，北京  100190; (2)中南大学物理科学与技术学院，长沙  410083；北京凝聚态物理国家实验室，中国科学院物理研究所，北京  100190
Published: December 2020

Movement of intruder in jammed granular medium may result in interior reorganization of force chain structure. The form of drag force experienced by the intruder reflects the macro effect of the reorganization. By measuring the slow-pushing force of spheres intruding vertically into a granular bed, depth dependence of vertical drag force in jammed granular medium is studied experimentally. It is found that the drag force curve has a concave-convex transition with increasing penetration depth and the drag force follows different depth dependence in different regimes. In shallow regime, there is an exponent 1.3 power-law depth dependence; while in deep regime, the drag force is not saturated but has a tendency of power-law dependence with exponent 0.3. By studying the properties of the inflection point of the concave-convex transition, we have shown that the slowdown of the increasing rate of drag force is not a result of sidewall support proposed by previous researchers, but a result of volume effect of the intruder in granular medium. Moreover, the hydrostatic model is not appropriate in the case of slow drag and static granular bed, for not only the depth dependence of the drag force is higher than linear, but also its coefficient is much greater than the hydrostatic estimate.
Fire patterns of coupled FitzHugh-Nagumo neurons exposed to external electric field
Authors: Wang Bao-Yan  , Xu Wei  , Xing Zhen-Ci  ,   西北工业大学理学院，西安  710072
Published: December 2020

This paper investigates the dynamic behavior of the two coupled FitzHugh-Nagumo neurons connected by coupling. The system exhibits p∶q phase-locked （i.e. a periodic oscillation defined as p action potentials generated by q cycle stimulations） depending on the value of stimulus frequency. Whether phase-locking occurs or not relies on the fire patterns of the system. Furthermore, the stimulus frequency and coupling intensity can stir up rich bifurcation respectively, and the stimulus frequency affects the system fire patterns more obviously. The study has also found that chaotic behavior is the transition state to other fire patterns.
Analysis on the parameters of the current waveforms of triggered lightning
Authors: Zhao Yang  , Qie Xiu-Shu  , Kong Xiang-Zhen  , Zhang Guang-Shu  , Zhang Tong  , Yang Jing  , Feng Gui-Li  , Zhang Qi-Lin  , Wang Dong-Fang  ,   (1)山东省雷电防护技术中心，济南  250031; (2)中国科学院大气物理研究所中层大气和全球环境探测重点实验室，北京  100029; (3)中国科学院寒区旱区环境与工程研究所西部气候环境与灾害实验室，兰州  730000
Published: December 2020

Artificially triggered lightning experiments were carried out at Binzhou, Shandong Province, China during summer form 2005 to 2008. The discharge current at the channel base of triggered lightning were measured. The geometric mean value of the peak current for 21 negative return strokes was 14.6kA, the geometric mean of the 10%—90% risetime was 2.3μs, the geometric mean of the half peak width was 17 μs and the geometric mean of the charge transfer within 1ms of return strokes was 1.2C. There was essentially no correlation between the return stroke peak current and 10％—90% risetime or between return stroke peak and the width of the current waveform at half of its peak value. No dependence of peak current on grounding resistance was found either. There is correlation between return stroke current peak and charge transfer within 1ms after return stroke initiation, and the correlation between return stroke peak and the stepness of the front waveform of return stroke was also found. Compare the parameters of the triggered lightning with natural cloud to ground lightning, it was found that the triggered lightning stroke is similar to subsequent stroke of natural lightning. So the results of triggered lightning can be used to the lighting protection.
The determination of observation weight in inversion ocean duct using radar clutter
Authors: Sheng Zheng  , Huang Si-Xun  , Zhao Xiao-Feng  ,   解放军理工大学气象学院，南京  211101
Published: December 2020

Observation weight is generally not considered in the works on inversion ocean duct using radar echo. In order to solve the problem，an exponential expression similar to that of the electromagnetic wave propagation loss is used to describe change of observation weight with distance，and the standard statistics retrieval algorithm is used to test the effect of retrieval speed and precision caused by different observation weight. Experimental results show that the exponential expression can approprielly describe change of observation weight with distance，and the determination of loss index is of great importance. Reasonable observation weight can eviclently improve the retrieval speed and precision，and the optimal loss index is different for electromagnetic waves of different frequency.
Phase screen distribution for simulating laser propagation along an inhomogeneous atmospheric path
Authors: Qian Xian-Mei  , Zhu Wen-Yue  , Rao Rui-Zhong  ,   中国科学院安徽光学精密机械研究所大气光学中心，合肥  230031
Published: December 2020

With respect to the problem of light uplinks and downlinks in atmospheric turbulence, the strength of turbulence changes greatly along the path. The distribution of phase screens on the path is a vital problem to be solved in the numerical simulation of light propagation. Three different approaches: uniform distributed phase screen （UDPS）, equivalent Rytov index-interval phase screen （ERPS） and equivalent Fried parameter-interval phase screen （EFPS） are discussed. It is found that, by using ERPS method, the distance between phase screens changes automatically according to the strength of turbulence, and the fluctuation of turbulence can also be sampled sufficiently. Under the precondition that the critera for phase screen interval are satisfied, the Rytov index interval of ERPS could be any arbitrary constant value. Statistical results show that, even the Rytov index interval changes by one order of magnitude, both effective beam radius and Strehl ratio of energy change for only 2.1%. And simulated results agree well with theoretical ones. All this indicates the stability and reliability of the ERPS method.
Analysis of the stability of temperature networks (part Ⅰ)——The influence of extreme events
Authors: Wang Xiao-Juan  , Gong Zhi-Qiang  , Zhou Lei  , Zhi Rong  ,   (1)扬州大学物理科学与技术学院，扬州  225002; (2)扬州大学物理科学与技术学院，扬州  225002；常熟理工学院物理与电子工程学院，常熟  215500; (3)扬州大学物理科学与技术学院，扬州  225002；国家气候中心，气候诊断预测室，北京  100081; (4)扬州大学物理科学与技术学院，扬州  225002；中国科学院大气物理研究所东亚区域气候-环境重点实验室，北京  100029
Published: December 2020

The spatial and temporal stability of temperature correlation network is analyzed based on extreme temperature, El Niňo/La Niňa abnormal year, key areas of temperature change and high frequent year of extreme respectively. Results show that, the connectivity of network decreases by filtering out extreme temperature, property of the network at the inflexion P=0.1 or 0.9, might be defined as the of boundary of extreme temperature. La Niňa network possesses more significan links and higher clustering coefficient than the El Niňo network, which indicates that the former is more communicative and more stable than the latter. And based on these statistical properties, we verified that during La Niňa years predictability is higher compared to El Niňo years and normal years. Furthermore, we also verified that during high frequency years of extreme high temperature predictability is higher than high frequent years of extreme low temperature and normal years. We also come to the conclusion that middle and east tropical Pacific （180°E—80°E，15°N—15°S） are key areas of global temperature changes, and exlernal forces acting on these areas have great effect on global temperature change.
A simulation study of the atmospheric neutron environment in near space
Authors: Cai Ming-Hui  , Han Jian-Wei  , Li Xiao-Yin  , Li Hong-Wei  , Zhang Zhen-Li  ,   (1)中国科学院空间科学与应用研究中心，北京  100190; (2)中国科学院空间科学与应用研究中心，北京  100190；中国科学院研究生院，北京  100049
Published: December 2020

In this paper, a Monte Carlo simulation model based on atmosphere model, cosmic ray model and geomagnetic field model has been developed for the near space atmospheric neutron environment. The neutron distributions induced by cosmic rays and solar particles have been calculated separately. What is more, the influence of cutoff rigidity to neutron flux has been analyzed. By comparing with ARM model, we can draw the conclusion that our model is credible and excellence in calculating neutron flux induced by solar particles. The model could be applied in many fields, such as evaluating single event effects of microelectronics and analyzing radiation dose received by the air crew.
Statistical characteristics of gamma ray and radio emission of BL Lac object
Authors: Li Wei-Hu  , Yuan Rong  ,   西藏农牧学院公共教学部,林芝  860000
Published: December 2020

A sample including 22 BL Lac objects was collected. The possible correlations between the γ-ray emission at 1 GeV and the radio emission at 8.4GHz or 5.0GHz were investigated. Main results are as follows: 1） for minimum γ-ray data, there is no correlation between γ-ray and radio flux density. For maximum and average data, there are good correlations between γ-ray and radio emissions, with the maximum correlation coefficient reaching 0.85, and the chance probability p-4; 2） there are weak correlations between γ-ray spectral index and the radio spectral index. Therefore, the γ-ray radiation was the SSC process.
A mixed search model of Brownian particles
Authors: Pu Cun-Lai  , Pei Wen-Jiang  , Wang Shao-Ping  ,   东南大学信息科学与工程学院，南京  210096
Published: December 2020

According to the basic theories of Brownian motion, a mixed search model is proposed. By dividing every search process into two phases: single random walk search and multiple random walk searches, it improves the efficiency of a single random walk while reduces the hardware cost of multiple random walks. Compared with the mixing navigation model proposed by Tao Zhou, our model converges much faster on complex networks with lower hardware cost. We also compared two selection strategies: random selection and target selection, and found that our model improves the search efficiency further on complex networks when employed with target selection, which is prefered to the nodes of the highest degrees. Besides, by simulations on scale-free networks, we found the efficiency of our model is far higher than the single random walk and comparable to multiple random walks while the hardware cost of our model is far less. Finally, we give an absorption strategy to reduce the traffic load produced by the MS model.
Characteristics of intrinsic optical bistability and parameter optimization in Tm3+/Yb3+ codoped laser crystal
Authors: Li Li  , Zhang Xin-Lu  , Cui Jin-Hui  , Chen Li-Xue  ,   (1)哈尔滨工程大学理学院，哈尔滨  150001; (2)哈尔滨工程大学理学院，哈尔滨  150001； 哈尔滨工业大学物理系，哈尔滨  150001; (3)哈尔滨工业大学物理系，哈尔滨  150001
Published: December 2020

Intrinsic optical bistability （IOB） in Tm3+/Yb3+ codoped laser crystal under 650 nm laser excitation is theoretically studied. Based on the theory of nonlinear coupled rate equations, we numerically analyze IOB evolutions of the populations at Tm3+/Yb3+ energy levels, and the influence of system parameters on IOB and the dynamic operation of bistable hysteresis loop. The simulation result shows the fluorescence IOB in visible-infrared spectra of Tm3+/Yb3+ codoped laser crystal under photon avalanche pumping scheme. It is found that IOB phenomena can be largely enhanced by optimizing the Tm3+/Yb3+ concentration ratio, choosing low phonon-energy crystal host and using crystal cooling technology, and also by tuning the pump laser to match the resonant frequency of Tm3+ excited-state absorption transition. Through tuning the pump laser wavelength and adjusting the rate of change in pump intensity, the controllable IOB switching can be achieved.
Diffusion in a linear oscillator driven by colored noises with white cross-correlation
Authors: Chen De-Yi  , Wang Zhong-Long  ,   三峡大学理学院物理系，宜昌  443002
Published: December 2020

The diffusion in a linear oscillator driven by white cross-correlation colored noises in which one of the noises is modulated by a biased period signal is studied. Effects on d versus Q curve, d versus D curve, and d versus Ω curve by multiplicative colored noise self-correlation time τ1 as well as additive colored noise self-correlation time τ2 are revealed. Here d, Q, D, and Ω denote the diffusion coefficient of the oscillator, the intensity of the signal modulated noise, the intensity of the pure additive noise, and the signal frequency, respectively. It is found that a minimum exists in the d versus Q curve and the d versus D curve respectirely. The diffusion coefficient as a function of signal frequency Ω exhibits a pronounced maximum at Ω=Ω, here Ω　is the oscillator frequency. The condition of diffusion coefficient d=0 is derived.
Oscillations of granular mixture gases with vertical vibration
Authors: Yang Xian-Qing  , Liu Fu  , Jia Yan  , Deng Min  , Guo Hai-Ping  , Tang Gang  ,   (1)中国矿业大学理学院，徐州  221008; (2)中国矿业大学理学院，徐州  221008；北京师范大学物理系，北京  100875
Published: December 2020

The oscillation phenomena for granular mixture within a vertically vibrated container are investigated with the event-driven method. The container consists of two rooms with equal size separated by a clapboard with certain height，and two kinds of granules with the radius of one twice as larger as the other are used. Investigation results indicate that the period of oscillation of granula sharply increases with the decrease of the ratio of density between two kinds of particles. The relations of the ratio of density to the ratio of vertical height of the two kinds of particles are calculated, which shows that the main factor of granular oscillation is not the “Brazil nut effect” or “reverse Brazile nut effect”. The granular temperature is calculated and found to be relevant to oscillations of mixture. When the temperature of the small particle is above a certain value, oscillations of granular mixture occur. According to hydromechanical equations proposed by Viridi et al., these equations are correspondly modified and may explain the relations between the period of oscillation and the ratio of granular density.
Structure and electric transport properties of the spin ladder compound Sr14(Cu0.97M0.03)24O41(M=Zn, Ni, Co)
Authors: Cheng Li  , Wang Li-Li  , Pu Shi-Zhou  , Hu Ni  , Zhang Yue  , Liu Yong  , Wei Wei  , Xiong Rui  , Shi Jing  ,   (1)武汉大学物理科学与技术学院，教育部声光材料与器件重点实验室，武汉  430072; (2)武汉大学物理科学与技术学院，教育部声光材料与器件重点实验室，武汉  430072；武汉大学化学与分子科学学院，湖北省有机高分子光电材料重点实验室，武汉  430072; (3)武汉大学物理科学与技术学院，教育部声光材料与器件重点实验室，武汉  430072；武汉大学化学与分子科学学院，湖北省有机高分子光电材料重点实验室，武汉  430072 ；中国科学院国际材料物理中心，沈阳  110016
Published: December 2020

Polycrystalline samples of Sr14Cu24O41 and Sr14（Cu0.97M0.03）24O41（M=Zn, Ni, Co） were synthesized by standard solid state reaction method. All samples are single phase as identified by X-ray diffraction, no regular shift of lattice parameters a, c is found, but the lattice parameter b increases slightly with doping magnetic ions Ni and Co, and has no change with doping non-magnetic ion Zn, respectively. Selected area electron diffraction experiments show that Zn,Ni and Co ions may substitute for Cu ions in the chain. All the doping compounds are still semiconductors and have a crossover temperature Tρ like the parent phase Sr14Cu24O41. The influence of magnetic ion Ni or Co doping on the resistivity is smaller than that of non-magnetic ion Zn doping, while the influence of non-magnetic ion Zn doping on crossover temperature is smaller than that of magnetic ion Ni or Co doping.
Dynamical design and analysis of continuous chaos frequency modulation signal
Authors: Jiang Fei  , Liu Zhong  , Hu Wen  , Bao Bo-Cheng  ,   (1)南京航空航天大学信息科学与技术学院，南京  210016; (2)南京理工大学电子工程系，南京  210094; (3)南京理工大学电子工程系，南京  210094；江苏技术师范学院电气信息工程学院，常州  213001
Published: December 2020

On the basis of continuous chaos time scaling, dynamical design principle of continuous chaos frequency modulation signal (CCFMS) is proposed. Subsequently, a detailed implementation by taking Colpitts circuit as the example is given. Dynamical characteristics of CCFMS are analyzed by reconstructing the attractor and computing the Lyapunov exponent. Results show that the maximum Lyapunov exponent of CCFMS is the same as that of chaotic signal. Dynamical design of CCFMS can be simply realized and its system parameters can be easily controlled, meanwhile the signal expression is consistent with the mathematical expression of CCFMS.
Precipitation of Cu-rich clusters in reactor pressure vessel model steels and embedded-atom method potentials
Authors: Lin Min-Dong  , Zhu Juan-Juan  , Wang Wei  , Zhou Bang-Xin  , Liu Wen-Qing  , Xu Gang  ,   上海大学材料研究所，上海  200072
Published: December 2020

Atom probe tomography characterization and thermal aging method have been employed to investigate the precipitation of Cu-rich clusters in reactor pressure vessel （RPV） model steels with and without the addition of Ni alloying element. It is observed that the number density of Cu-rich clusters in the PRV model steel with the addition of Ni （0.84 wt%） is higher than that without the addition of Ni. The segregation of nickel in the Cu-rich clusters and at the boundaries of clusters/matrix was also observed. It is found that the nickel alloying element can promote the precipitation of Cu-rich clusters in RPV model steel. An analytical embedded atom method model of Fe-Cu and Fe-Cu-Ni system is constructed on the basis of the physical properties of pure constituents Fe, Cu and Ni. The calculation results show that the nickel （1 at%） can promote the precipitation of Cu-rich clusters. The calculation results agree with the results of experiments.
Controlled growth of silicon nanowires by solid-liquid-solid method and their formation mechanism
Authors: Peng Ying-Cai  , Fan Zhi-Dong  , Bai Zhen-Hua  , Ma Lei  ,   (1)河北大学电子信息工程学院，保定  071002; (2)河北大学电子信息工程学院，保定  071002；中国科学院半导体研究所半导体材料科学重点实验室，北京  100083
Published: December 2020

High quality silicon nanowires （SiNWs） were grown directly from n-（111） silicon single crystal substrate by using Au film as a metallic catalyst. The diameter and length of the formed nanowires are 30—60 nm and from several micrometers to sereral tens of micrometers, respectively. The effects of Au film thickness, annealing temperature, growth time and N2 gas flow rate on the formation of the nanowires were experimentally investigated. The results confirmed that the silicon nanowires with controlled diameter, length, shape and orientation can be obtained via reasonably choosing and optimizing various technical conditions. The formation process of the silicon nanowires is analyzed qualitatively based on solid-liquid-solid growth mechanism.
Preparation and characterization of Cu(In, Ga)(Se, S)2 thin films by sulfurization of electrodeposited Cu(In, Ga)Se2 precursors
Authors: Lai Yan-Qing  , Kuang San-Shuang  , Liu Fang-Yang  , Zhang Zhi-An  , Liu Jun  , Li Jie  , Liu Ye-Xiang  ,   中南大学冶金科学与工程学院，长沙  410083
Published: December 2020

The solar cell light absorber Cu（In,Ga）（Se,S）2（CIGSS） thin films were prepared by annealing the electrodeposited Cu（In,Ga）Se2（CIGS） precursors in H2S ambient at 500 ℃. The precursors and annealed films were characterized by energy dispersive X-ray spectroscopy, Auger electron spectroscopy, scanning electron microscopy, X-ray diffraction and Raman scattering. The results show that the complete removal of oxygen atom from the film and a substitution of Se by S can be achieved by H2S-annealing. Furthermore, the depth profiles of constituent elements become more uniform, and the Cu-Se micro-phase can be eliminated by H2S-annealing. Moreover, the CIGSS films have good crystallinity and smaller crystal lattice parameters with S and Ga incorporation into the chalcopyrite structure.
Propagation of shockwave in nanocrystalline copper: Molecular dynamics simulation
Authors: Chen Kai-Guo  , Zhu Wen-Jun  , Ma Wen  , Deng Xiao-Liang  , He Hong-Liang  , Jing Fu-Qian  ,   (1)中国工程物理研究院流体物理研究所冲击波物理与爆轰物理国防科技重点实验室,绵阳  621900; (2)中国工程物理研究院流体物理研究所冲击波物理与爆轰物理国防科技重点实验室,绵阳  621900；国防科学技术大学物理系，长沙  410073; (3)中国工程物理研究院流体物理研究所冲击波物理与爆轰物理国防科技重点实验室,绵阳  621900；国防科学技术大学物理系，长沙  410073；四川大学物理科学与技术学院，成都  610064; (4)中国工程物理研究院流体物理研究所冲击波物理与爆轰物理国防科技重点实验室,绵阳  621900；四川大学物理科学与技术学院，成
Published: December 2020

The propagation of shockwave in nanocrystalline copper has been studied by means of molecular dynamics simulation. The samples are prepared by Voronoi method and crystalline orientations of each grain are limited by three conditions. The result shows for the first time that nanocrystalline copper shows the phenomenon of multi-yield under shock loading, and the shockwave has a multi-wave structure. The profiles of shock-front suggest grain boundary sliding and dislocation emmision in sequence. The shock-front consists of an elastically deforming area, a plastically deforming area dominated by grain boundary sliding and a plastically deforming area dominated by dislocation movement. There are irregularities on both elastic wave and plastic wave, and the former is obvious than the latter.
The feature extraction of epileptic EEG signals based on nonlinear prediction
Authors: Meng Qing-Fang  , Zhou Wei-Dong  , Chen Yue-Hui  , Peng Yu-Hua  ,   (1)济南大学信息科学与工程学院，济南  250022; (2)济南大学信息科学与工程学院，济南  250022；山东大学信息科学与工程学院，济南  250100; (3)山东大学信息科学与工程学院，济南  250100
Published: December 2020

Based on the nonlinear time series prediction，a feature extraction method for epileptic EEG signals using nonlinear prediction is proposed to automatically detect the epileptic EEG from EEG recordings. To reconstruct the phase space，the approach of determining the embedding dimension based on nonlinear predictability is used to determine the embedding dimension of the EEG signals. The experimental results show that the feature extracted with the method based on nonlinear prediction could clearly distinguish the epileptic EEG from the normal EEG，and the proposed nonlinear feature extraction method is fit for the small set time series and is stable to noise.
Improved properties of light emitting diode by rough p-GaN grown at lower temperature
Authors: Xing Yan-Hui  , Han Jun  , Deng Jun  , Li Jian-Jun  , Xu Chen  , Shen Guang-Di  ,   北京工业大学电子信息与控制工程学院，北京  100124
Published: December 2020

GaN: Mg films have been grown on sapphire at low temperature by metal-organic chemical vapor deposition, the properties of different source flux GaN: Mg materials were studied. When the molar ratio of CP2Mg and TMGa is between 1.4×10-3 and 2.5×10-3, the quality of crystal was improved with the increasing molar ration, and the hole concentration was increased linearly. When the molar ratio is 2.5×10-3，the concentration is equal to that of the film grown at higher temperature, and the surface morphology is more coarser. Taking the p-GaN layer with molar ratio of CP2Mg and TMGa of 2.5×10-3　as the light-emitting diode, when the inject current is 20 mA, the output light power was increased by 17.2%.
Optimization design of high linearity AlxGa1-xN/AlyGa1-yN/GaN high electron mobility transistor
Authors: Cheng Zhi-Qun  , Zhou Xiao-Peng  , Hu Sha  , Zhou Wei-Jian  , Zhang Sheng  ,   杭州电子科技大学电子信息学院,射频电路与系统教育部重点实验室，杭州  310018
Published: December 2020

A novel composite-channel AlxGa1-xN/AlyGa1-yN/GaN high electron mobility transistor has designed and optimized. The influence of the two-dimensional electron gas and electric field on device structure parameter is obtained from the self-consistent solution based on the theory of semiconductor energy band and quantum well. The influence of the layer structure of the device on its performance is obtained from simulation using TCAD software. Combining the results of theoretical analysis and simulation, the optimized structure Al0.31Ga0.69N/Al0.04Ga0.96N/GaN HEMT is proposed. The simulation results show that the device with gate length of 1 μm and gate width of 100 μm has the maximum transconductance of 300 mS/mm and small fluctuation in the gate voltage of from -2 V to 1 V, which shows the excellent linearity of the device. The maximum current density of 1300 mA/mm, the cut-off frequency of 11.5 GHz and a maximum oscillation frequency of 32.5 GHz are obtained.
Integration of organic thin-film transistor and polymer light-emitting diodes
Authors: Zou Jian-Hua  , Lan Lin-Feng  , Xu Rui-Xia  , Yang Wei  , Peng Jun-Biao  ,   (1)华南理工大学高分子光电材料及器件研究所，广州  510640; (2)华南理工大学高分子光电材料及器件研究所，广州  510640；华南理工大学特种功能材料及其制备新技术教育部重点实验室，广州  510640
Published: December 2020

We investigated the technology and the related physical problems for integrating organic thin-film transistor （OTFT） and polymer light-emitting diode （PLED）. The OTFT uses Pentacene as the active medium, Ta2O5 as dielectric layer, Ta as gate electrode and Au as source/drain electrodes. The structure of PLED device is ITO/PEDOT:PEO （polyethylene oxide）/P-PPV or MEH-PPV/Ba/Al. The PEDOT:PEO, P-PPV and MEH-PPV film layers were obtained by using screen printing technology. The transistors have a threshold voltage of -7.1 V and carrier mobility of 0.91 cm2/（V·s）. The luminance of the PLEDs with P-PPV and MEH-PPV emissive layer when were driven by OTFT could reach 124 and 22 cd/m2, and the maximal luminous efficiency are 12.4 and 1.1 cd/A, respectively.
Shot noise in the semiconductor/ferromagnetic d-wave superconductor tunnel junction
Authors: Liang Zhi-Peng  , Dong Zheng-Chao  ,   (1)淮阴师范学院物理系，淮安  223001; (2)苏州大学物理科学与技术学院，苏州  215006；淮阴师范学院物理系，淮安  223001
Published: December 2020

Considering the dependence of the gap on the exchange energy in ferromagnetic d-wave superconductor, we use an extended Blonder-Tinkham-Klapwijk approach to investigate the shot noise in semiconductor/ferromagnetic d-wave superconductor junction by solving the Bogoliubov-de Gennes（BdG） equation. It is shown that the exchange energy h0 in the ferromagnetic d-wave superconductor may induce a split of the shot noise double-peak at zero-bias and the energy gap peak, and the interval between the two split peaks is equal to 2h0; furthermore, with the increasing exchange energy h0, the shot noise and the ratio of shot noise power to average current are restrained.
Energy transfer processes and mechanisms in Tm3+ singly doped and Tm3+/Ho3+ codoped tellurite glass
Authors: Chen Gan-Xin  , Zhang Qin-Yuan  , Zhao Chun  , Shi Dong-Mei  , Jiang Zhong-Hong  ,   (1)湖南人文科技学院通信与控制工程系，娄底  417000；华南理工大学特种功能材料及制备新技术教育部重点实验室,光通讯材料研究所,广州  510641; (2)华南理工大学特种功能材料及制备新技术教育部重点实验室,光通讯材料研究所,广州  510641
Published: December 2020

Energy transfer processes of Tm3+ singly doped and Tm3+/Ho3+-codoped TeO2-WO3-ZnO glass have been investigated under excitation of 808 nm diode laser and the involved mechanisms are discussed. The microscopic parameters and critical radii are calculated by using Dexter model and their characteristics are analyzed. The Inokuti-Hirayama model improved by Vila et al. is utilized to fit the fluorescence decay curves of Tm3+. The results indicate that there are not only Inokuti-Hirayama-type solution but also localized interaction solution in the energy transfer processes of Tm3+ and Ho3+. Furthermore, the contribution of the localized interaction increases with the increasing of the concentrations of Tm3+ and Ho3+.
Effects of radio-frequency bias on silicon oxide films deposited by dual electron cyclotron resonance-radio frequency hybrid plasma
Authors: Ke Bo  , Wang Lei  , Ni Tian-Ling  , Ding Fang  , Chen Mu-Di  , Zhou Hai-Yang  , Wen Xiao-Hui  , Zhu Xiao-Dong  ,   中国科学技术大学近代物理系，中国科学院基础等离子体物理重点实验室，合肥  230026
Published: December 2020

Silicon oxide films were deposited in electron cyclotron resonance-radio frequency dual hybrid plasmas using a mixture of HMDSO and oxygen as source gases, and optical emission spectroscopy was employed to investigate the gas phase species in the plasma. It is found that both the deposition rate and the chemical bonds of films are significantly affected by the radio frequency bias. The deposition rate is slightly increased when a low direct current self-bias is applied, and is reduced with the increasing self-bias due to strengthened ion bombardment. The ratios of O to Si in the films deposited under the bias frequency of 400 kHz are above 2∶1, nearly the same as that under 13.56 MHz. However, the content of carbon under 400 kHz bias is much higher than that under 13.56 MHz. The reason is that the application of the high frequency bias of 13.56 MHz not only strengthens ion bombardment on the material surface, but also induces the variations of the bulk plasmas including the increase of O atom density, while the main effect of the bias of 400 kHz is only to strengthen ion bombardment.
Spatial resolution of pinhole single photon emission computed tomography imaging
Authors: Dai Qiu-Sheng  , Qi Yu-Jin  ,   中国科学院上海应用物理研究所，上海  201800
Published: December 2020

The spatial resolution of pinhole single photon emission computed tomography （SPECT） imaging is usually estimated according to Anger’s empirical formula, which could result in a large inaccuracy in experimental measurement. We present a more accurate formula based on the analysis of physical processes of pinhole imaging. The effectiveness of the proposed formula was evaluated by accurate Monte Carlo simulations and experiments of the phantom imaging. The images were reconstructed using three\|dimensional iterative OSEM algorithm. Then the effects of the voxel size, the geometrical mapping of the projection matrix and the ratio of detector size to imaging object size, on the spatial resolution were discussed. The experiment results show that the spatial resolution estimated by the proposed formula is about 10% smaller than the experimental value while the estimation by the Anger’s formula is about 60% larger than the experimental value. Therefore, our proposed formula is more accurate than Anger’s formula for predicting the spatial resolution of pinhole SPECT imaging, and it can be utilized for design and use of pinhole SPECT system.
Advective vorticity equation and its application to the vorticity variation of typhoon Bilis in 2006
Authors: Zhou Yu-Shu  , Ran Ling-Kun  ,   中国科学院大气物理研究所，北京  100029
Published: December 2020

The vorticity equation in the form of momentum cross multiplication is derived in pressure coordinate, in which the divergence term in the classic vorticity equation （CVE） does not appear. This vorticity equation in momentum cross multiplication form involves the rotation effect of the horizontal wind advection, which can be called the advective vorticity equation （AVE）. Because the rotational effect of horizontal wind advection can be directly analyzed on the synoptic charts, this equation is easily applied to operational weather analysis. The vorticity and its tendency of typhoon Bilis occurred in July 2006, it is analyzed and the results show that the distributions of the vertical vorticity tendencies from the two equations are similar except that the values of AVE is larger than that of CVE, and positive vorticity tendency from AVE is more concentrated than that of CVE. The detailed analyses of the three terms on the right hand side of AVE indicated that the advective term is a leading factor in determining the change of vertical vorticity for the development of the typhoon Bilis. When the vorticity induced by the rotational effect of horizontal wind advection plays a dominant role, AVE shows advantages for the diagnosis and analysis of synoptic systems. Thus, the AVE is useful for analysis of the change of vorticity and diagnosis of the movement for typhoon Bilis. Furthermore, the tendency of the term related to geostrophic vorticity and divergence always accords with the track of Bilis, which means this term can be used as an indicator for track prediction of typhoon.
Defocus and astigmatic aberration of the turbulent atmosphere and the intensity distribution of a vortex carrying Gaussian beam
Authors: Zhao Gui-Yan  , Zhang Yi-Xin  , Wang Jian-Yu  , Jia Jian-Jun  ,   (1)江南大学理学院，无锡  214122; (2)中国科学院上海技术物理研究所，上海  200083
Published: December 2020

The effects of defocus and astigmatism aberration of the turbulent atmosphere on the intensity distribution of a focused vortex carrying Gaussian beam are investigated. The integral expression of the intensity distribution on the focal plane in slant path is derived from the extended Fresnel-Kirchhoff diffraction integral and the quadratic approximation of phase structure function. And the influences of the three factors, turbulent strength, the propagation distance and the topological charge of the initial beam, are investigated by numerical calculation. Our results show that in weak turbulent region, the effects of defocus and astigmatism aberration in turbulent atmosphere on the intensity distribution of a vortex carrying Gaussian beam are very small and can be ignored. However, in the middle turbulent region, the effects of defocus and astigmatism are pronounced. As the propagation distance and the turbulent strength increase, both aberrations cause the decrease of the intensity peak value, the spreading of the beam, and the stretching of the dark core. For the beams with single topological charge, under the influence of astigmatism, the peak value of the intensity decreases more seriously, the intensity of the secondary maximum stripe increases much faster, and the focal spot expands more than the effect of defocus aberration. Compared with single topological charge, the effects of defocus and astigmatism of vortex beam with double topological charge are more obvious. The focal spots are expanded, and the secondary maximum stripes are more obvious. However, under the effect of astigmatism, because of the reduction of the coherence and the deflection effect of the beam, the dark core on the focal plane tends to break into two dark regions separated by a bright region.
Effect of electron screening on the rapid neutron capture process
Authors: Zhang Jie  , Wang Shao-Feng  ,   (1)重庆大学结构与功能研究所,重庆  400044; (2)重庆大学结构与功能研究所,重庆  400044；西华师范大学理论物理研究所,南充  637002
Published: December 2020

We investigate a weak electron screening effect on the electron capture of proton in the neutrino-driven wind of proto-neutron stars. Our results show that the electron screening has little influence on specific heating rate, entropy and other physical parameters in the wind. However, it improves electron fraction obviously, which strongly supports the latest nucleosynthesis of rapid neutron capture process.
(G'/G)-expansion method and novel fractal structures for high-dimensional nonlinear physical equation
Authors: Li Bang-Qing  , Ma Yu-Lan  , Xu Mei-Ping  ,   北京工商大学计算机与信息工程学院,北京 100048
Published: December 2020

The （G′/G）-expansion method is extended to construct non-traveling wave solutions and explore the fractal structure for high dimensional nonlinear physical equation. As an example, a series of non-traveling solutions is obtained for the （2+1）-dimensional dispersive long wave system with variable coefficient. Furthermore, by setting properly the arbitrary functions in the solutions, a class of novel fractal structures, namely, the cross-like fractal structures are firstly observed.
On the evolution of Couette flow energy
Authors: Zhang Liang  , Fu Wei-Ji  , Zhang Li-Feng  , Wu Hai-Yan  , Huang Hong  ,   (1)94855部队，衢州  324001; (2)96251部队，洛阳  471003; (3)解放军理工大学气象学院地球物理研究室，南京  211101; (4)解放军理工大学气象学院地球物理研究室，南京  211101；96165部队，乐平  333300
Published: December 2020

In this paper, the Green function method is used to obtain the exact solution of Couette flow. By defining the Couette flow energy, the relative energy and the energy increase ratio, we discuss the relations between the structure of initial field and the evolution of Couette flow energy, the relations between the time corresponding to Couette flow energy attaining to its maximum and the structure of initial field together with the structure of initial field which can optimal excitated Couette flow energy increasing within a finite time interval. We further investigate the relations between the perturbed initial field and the evolution of Couette flow energy. The conclusions of this paper are supplementary to Farrell’s conclusions.
One-dimensional tunneling dynamics between two-component Bose-Einstein condensates
Authors: Li Gao-Qing  , Chen Hai-Jun  , Xue Ju-Kui  ,   (1)陇东学院物理与电子工程学院，庆阳 745000; (2)西北师范大学物理与电子工程学院，兰州 730070
Published: December 2020

One-dimensional quantum tunneling dynamics between two-component Bose-Einstein condensates confined in a double-well magnetic trap is investigated. One-dimensional Gross-Pitaevskii equations for two-component Bose-Einstein condensates are derived from the three-dimensional ones. We derive Feynman equations from one-dimensional Gross-Pitaevskii equations. To study tunneling dynamics we solve Feynman equations in terms of a completely numerical procedure. In contrast to single-component condensates between two-component condensates, we find that this system can take on abundant tunneling results, the full tunneling dynamical behavior is summarized in phase portrait with constant energy lines. It is found that this system can achieve self-trapping when increase interatomic interactions exceed a critical value. We give the analytical critical expressions of interatomic interactions from the system Hamiltonian.
Realization of quantum single pendulum on macroscopic level
Authors: Ning Bo-Yuan  , Ma Jun-Shan  , Zhuang Jun  , Ning Xi-Jing  ,   (1)复旦大学光科学与工程系，上海  200433; (2)复旦大学现代物理研究所，上海  200433；教育部应用离子束物理重点实验室; (3)上海理工大学光电信息与计算机工程学院，上海  200093
Published: December 2020

Dealing with the motion of single pendulum, classical mechanics shows, by the effective center of mass method, that the pendulum ball performs periodical spatial movement. However, using the same method, quantum mechanics presents a totally different answer: the pendulum ball moves randomly in space without a definite period. We provide the criteria conditions for the two different predictions, and propose the experimental conditions for the ball to obey quantum mechanics. Our results show that it is quite easy with current experimental apparatus to observe the spatial quantum transition of a macroscopic objects of the micrometer-seale.