bluuebunny/crossref_metadata_2025 huggingface dataset:
Observation of macroscopic postsolitons in ultrashort ultraintense laser-plasma interaction
Authors: Zhu Bin  , Gu Yu-Qiu  , Wang Yu-Xiao  , Liu Hong-Jie  , Wu Yu-Chi  , Wang Lei  , Wang Jian  , Wen Xian-Lun  , Jiao Chun-Ye  , Teng Jian  , He Ying-Ling  ,   (1)哈尔滨工业大学物理系,哈尔滨  150001; (2)中国工程物理研究院激光聚变研究中心,绵阳  621900; (3)中国工程物理研究院激光聚变研究中心,绵阳  621900；哈尔滨工业大学物理系,哈尔滨  150001; (4)中国工程物理研究院激光聚变研究中心,绵阳  621900;四川大学原子核科学技术研究所，成都  610064; (5)中国工程物理研究院激光聚变研究中心,绵阳  621900；四川大学原子与分子物理研究所,成都  610065
Published: December 2020

Experiments were performed using ultrashort (30fs) ultraintense (up to 1018 W/cm2) laser pulse focused into underdense deuterium plasmas (ne＜1020/cm3). Macroscopic bubblelike structures were observed using monochromatic plasma irradiance imaging method. These structures are interpreted as the overdense shells of postsolitons generated in the plasma by the laser pulse, which is found to have important influence on the formation of plasma channel.
Relativistic Cherenkov source with modified photonic band-gap cells
Authors: Gao Xi  , Yang Zi-Qiang  , Hou Jun  , Qi Li-Mei  , Lan Feng  , Shi Zong-Jun  , Li Da-Zhi  , Liang Zheng  ,   (1)电子科技大学物理电子学院，成都  610054; (2)日本激光技术综合研究所,大阪
Published: December 2020

A relativistic Cherenkov source with slow wave system consisting of modified photonic band-gap cells is proposed and investigated. The high frequency structure simulator and three-dimensional particle-in-cell simulation code are used to study the dispersion characteristic of TM01-like mode and the interaction between electromagnetic wave and electron beam. The results show that, in the slow wave system with modified photonic band-gap cells, the TM01-like mode has much better azimuthal symmetry, the non-axisymmetry mode can be efficiently suppressed and the operation efficiency can be enhanced greatly.
Study of central plasma structure using soft X-ray signals
Authors: Ma Tian-Peng  , Hu Li-Qun  , Chen Kai-Yun  ,   (1)北方民族大学基础部，银川  750021; (2)中国科学院等离子体物理研究所，合肥  230031
Published: December 2020

A method for studying the central plasma structure using soft X-ray signals in the HT-7 tokamak is reported. Through analysing a typical discharge with MHD instability, the position and rotation direction of magnetic island are obtained from the soft X-ray signals. The magnetic island position and rotation direction are validated from the contour map of soft X-ray emissivity and the m=2 mode rotation direction observed on the Mirnov signals.
Growth kinetics and growth process control of nanocrystalline TiO2 anatase
Authors: Hu Lin-Hua  , Dai Jun  , Liu Wei-Qing  , Wang Kong-Jia  , Dai Song-Yuan  ,   中国科学院等离子体物理研究所太阳能材料与工程研究室，合肥  230031
Published: December 2020

Structural transformation of nanocrystalline titania prepared by sol-gel process with hydrolysis precursor titanium isopropoxide was investigated. The growth kinetics of TiO2 anatase was also studied. It is found that under acid conditions, the activation energies for the growth of anatase below and above 250℃ are (15.8±4.5) kJ/mol and (80.2±1.0) kJ/mol, respectively, which is due to the structural transformation from anatase to rutile resulting from the increasing temperature during the autoclave heating process. Under base conditions, the activation energy of anatase growth is (3.5±0.4) kJ/mol. The growth of anatase under acid conditions is slower than that under base conditions without phase transformation. That is, the growth of anatase becomes significant at higher temperature under acid conditions, whereas under base conditions, the crystallite growth is obviously accelerated by the longer autoclaving time. The above research results will contribute to realize the control of TiO2 nanoparticle size and will also provide us the theoretical and experimental bases for the mass production of TiO2nanoparticles in the future.
Synthesis of large-area, vertically aligned α-Fe2O3 nanowire and nanobelt arrays
Authors: Hai Kuo  , Tang Dong-Sheng  , Yuan Hua-Jun  , Peng Yue-Hua  , Luo Zhi-Hua  , Liu Hong-Xia  , Chen Ya-Qi  , Yu Fang  , Yang Yi  ,   低维量子结构与调控教育部重点实验室，湖南师范大学物理与信息科学学院，长沙  410081
Published: December 2020

Large-area (10 mm×10mm), vertically aligned α-Fe2O3 one-dimensional nanostructure (nanobelts and nanowires with controllable diameters) arrays are successfully synthesized by thermally oxidizing iron foil directly, which grow in the ［110］ direction of the hexagonal crystal. The morphology and microstructure of the synthesized arrays depend strongly on the growth conditions such as the oxygen pressure, temperature and reaction time. We found that the growth of α-Fe2O3 one-dimensional nanostructures follows a top-growth mechanism, in which the ratio of iron and oxygen atoms near the point of growth plays a key role.
Thermal dynamics properties of bcc Mo nanofilm from MD simulation
Authors: Jia Ming  , Lai Yan-Qing  , Tian Zhong-Liang  , Liu Ye-Xiang  ,   中南大学冶金科学与工程学院,长沙  410083
Published: December 2020

Using molecular dynamics simulation with the modified analytic embedded-atom method (MAEAM), we calculated Gibbs free energy and surface free energy of bcc Mo with high melting temperature Tf, and further obtained the Gibbs free energy of its nanofilms. Based on the Gibbs free energy of nanofilms, we investigated the heat capacity of molybdenum nanofilms at constant pressure or at constant volume. The analysis reveals that the molar heat capacity of bulk sample is lower than that of the nanofilms, and the difference increases with the decrease of the film thickness. It is also observed that such size effect of Mo nanofilm is not really significant until the thickness is less than about 15—20nm. It is the surface atoms that determine the size effect on the thermodynamic properties of nanofilms. The difference between CV and CP of nanofilms is firstly analysed quantitatively and the calculated result for CV/CP varies linearly with T/Tf and relates directly to film thickness.
Influence of helium on volume change and stability of titanium structure: An atomistic simulation
Authors: Chen Min  , Wang Jun  , Hou Qing  ,   四川大学原子核科学技术研究所辐射物理及技术教育部重点实验室，成都  610064
Published: December 2020

Molecular dynamics was employed to study the effects of the size of helium cluster and the helium content on the elastic properties and the volume change of the material under different pressures. We tried to analyse the cause that induced volume change of titanium and the instability of the system. With the increasing of helium content, the cohesive energy reduces, the external volume of the material expands, and the materials becomes unstable. When the size of He cluster is small, with the helium bubble growing, the cohesive energy rises, a volume contraction of the material occurs, and the system tends to keep stable. When the number of helium atoms in helium bubble is over 74, it is difficult for the helium bubble to grow.
Plastic deformation of helium bubble and void in aluminum under shock loading
Authors: Wang Hai-Yan  , Zhu Wen-Jun  , Deng Xiao-Liang  , Song Zhen-Fei  , Chen Xiang-Rong  ,   (1)四川大学物理科学与技术学院，成都  610064; (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重点实验室，绵阳  621900; (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重点实验室，绵阳  621900;河南理工大学材料科学与工程学院，焦作  454000;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重点实验室，绵阳  621900；四川大学物理科学与技术学院，成都  610064
Published: December 2020

The characteristic of microscopic plasticity associated with collapse of helium bubble and void in single-crystal aluminum under the same shock loading strength has been investigated by molecular dynamics (MD) simulations. The results show that both the helium bubble and the void collapse through the emission of shear dislocation loops, while prismatic dislocation loops are never observed in the simulations. The preferential dislocation nucleation sites are similar for the helium bubbles and the voids, but the number of dislocations emitted from the helium bubble outnumbers that from the voids, and the dislocation loops emitted from the helium bubbles move faster than that from the voids. Meanwhile, it is more difficult to emit dislocation loops from the leading side (the side which the shock hits first) of both the helium bubbles and the voids than from the trailing side. By analysing the resolved shear stress along the slip plane, we found that the internal pressure of the helium bubbles increase the resolved shear stress and make the dislocation emission from the helium bubbles much easier than from the voids. The curvature change from the leading side to the trailing side produced by the shock modifies the critical shear stress for dislocation nucleation, which explains the difference in the plasticity between the leading side and the tailing side of both the helium bubbles and the voids. The result will contribute to a better understanding of the microscopic mechanism through which irradiation damages affect the dynamic properties of metals.
Electronic structure and optical properties of ZnO doped with Fe and Ni
Authors: Hu Zhi-Gang  , Duan Man-Yi  , Xu Ming  , Zhou Xun  , Chen Qing-Yun  , Dong Cheng-Jun  , Linghu Rong-Feng  ,   (1)四川师范大学物理与电子工程学院&固体物理研究所,成都  610068; (2)四川师范大学物理与电子工程学院&固体物理研究所,成都  610068；贵州师范大学理学院，贵阳  550001; (3)四川师范大学物理与电子工程学院&固体物理研究所,成都  610068；重庆邮电大学光电工程学院,重庆  400065
Published: December 2020

The band structure, density of states, optical absorption properties and dielectric function of ZnO doped with Fe or Ni and co-doped with Fe and Ni have been investigated by using density functional theory. The calculated results show that the density of states near Fermi level is derived from Fe 3d and Ni 3d states. A new peak appears at 0.46eV in the imaginary part of dielectric function of doped ZnO. Moreover, the optical absorption spectrum shows an obvious red shift, and a strong peak is observed at 1.3eV after doping. The above results were qualitatively discussed in combination with the experimental and calculated results reported in the literature.
First-principles study on the electronic structures of the ladder compound NaV2O4F
Authors: Hu Fang  , Ming Xing  , Fan Hou-Gang  , Chen Gang  , Wang Chun-Zhong  , Wei Ying-Jin  , Huang Zu-Fei  ,   (1)吉林大学材料科学与工程学院,长春  130012; (2)吉林大学材料科学与工程学院,长春  130012；吉林大学物理学院,长春  130012; (3)吉林大学材料科学与工程学院,长春  130012；吉林师范大学凝聚态物理研究所,四平  136000
Published: December 2020

The electronic structures of ladder structural compound NaV2O4F are studied by first-principles calculations with pseudo-potential plane-wave method and spin-polarized generalized gradient approximation (GGA) based on density functional theory (DFT). Four possible spin-ordered states are simulated and the calculated results reveal that the magnetic ground state of NaV2O4F is the antiferromagnetic (AFM) state with AFM interactions both inside the rungs and along the ladder legs. The insulating behavior is successfully simulated with a band gap of about 1.0eV. According to crystal-field theory, the dxy orbitals of V atoms located in the VO4F pyramids have the lowest energy and are split from other d orbitals. The covalent interaction on the rungs becomes weak with the presence of F-ions. Using the calculated total energies for the various spin-ordered states of NaV2O4F, the spin exchange coupling constants are fit out with Noodleman's broken symmetry method. The calculated results indicate that there are ferromagnetic(FM) interactions between the ladders with competitive strength to that on the rungs and thereby NaV2O4F may not be a spin-ladder material.
Effect of wire width on strain distribution and bandgap in quantum-wire nanostructures based on continuum elasticity theory
Authors: Yao Wen-Jie  , Yu Zhong-Yuan  , Liu Yu-Min  , Lu Peng-Fei  ,   北京邮电大学光通信与光电子学研究院，光通信与光波技术教育部重点实验室，北京  100876
Published: December 2020

The strain distributions of quantum-wire structures are discussed by two methods, namely the continuum elasticity theory treated as a finite difference problem and the Green-function. Analytical expressions are derived for the strain fields with Green-function, which is simple for the regular shaped quantum-wire. The strain fields for arbitrary-shaped quantum-wire can be calculated by continuum elasticity theory and the influences of elastic constants are considered for different materials, although the results are less accurate. The effect of quantum-wire width on strain distribution and bandgap is analysed for InGaAs/GaAs quantum-wire nanostructures. The absolute magnitude of the strain in the bulk of the wire is attenuated significantly along the width direction. At the wire center, the strain-modified direct bandgap increases with the decrease in wire width.
First-principles study of electron field emission from the carbon nanotube with nitrogen doping and H2O adsorption
Authors: Chen Guo-Dong  , Wang Liu-Ding  , An Bo  , Yang Min  , Cao De-Cai  , Liu Guang-Qing  ,   西北工业大学应用物理系，西安  710072
Published: December 2020

The electron field emission performance of CNT doped with one nitrogen atom in different atomic layers and adsorbed with H2O molecules of different numbers was investigated through the first-principles calculations. The results show that the structure of the systems investigated is stable. The margin of the density of states (DOS) shifting towards low energy position increases with the applied electric field and the number of water molecules, and the HOMO/LUMO gap decreases with these parameters. The analysis of adsorption energy, DOS/LDOS, HOMO/LUMO and their gap indicates that N3CNT+βH2O system is more propitious to the electron′s field emission than other systems.
Ferromagnetic quantum phase transition in Co(S1-xSex)2 system
Authors: Yang Jin-Hu  , Wang Hang-Dong  , Du Jian-Hua  , Zhang Zhu-Jun  , Fang Ming-Hu  ,   浙江大学物理系，杭州  310027
Published: December 2020

In Co(S1-xSex)2 system, a transition from ferromagnetic to paramagnetic state occurs near x = 0.11. In order to research the physical properties of the samples near this transition, polycrystalline samples of Co(S1-xSex)2 (0.0≤x≤0.16) were prepared. And their structure and resistivity were measured. It is found that the ferromagnetic transition temperature TC is suppressed by Se doping in the relation TC～(1-x)1/2. And the ferromagnetic phase transition goes from the second to the first order. The temperature dependence of resistivity, ρ(T), shows a Fermi-liquid behavior, ρ(T)=ρ0+AT2, in Co(S1-xSex)2 (xρ(T) occurs in the samples near a critical concentration x=0.11. It is suggested that the phase transition near x=0.11 is a quantum phase transition, and the quantum critical spin fluctuation at zero temperature results in non-Fermi liquid behavior.
Generation of grid multi-scroll Chua’s chaotic attractors with combination of hysteresis and step series
Authors: Zhang Chao-Xia  , Yu Si-Min  ,   广东工业大学自动化学院，广州  510006
Published: December 2020

In this paper, a new approach to generating two types of grid multi-scroll chaotic attractors from canonical Chua’s circuit is reported. Different from the techniques reported in current literature for generating multi-scroll chaotic attractors by constructing only the same type of non-linear function, the present approach constructs both hysteresis series and step series in the same Chua's circuit, and extends the saddle-focus equilibrium points with index-2 in phase space by combining both series in different ways, which makes it possible to create two kinds of grid multi-scroll chaotic attractors. The effectiveness of this method has been verified by theoretical analysis, numerical simulation and circuit implementation.
A high-voltage and high-current photoconductive semiconductor switch and its breakdown characteristics
Authors: Shi Wei  , Tian Li-Qiang  , Wang Xin-Mei  , Xu Ming  , Ma De-Ming  , Zhou Liang-Ji  , Liu Hong-Wei  , Xie Wei-Ping  ,   (1)西安理工大学理学院应用物理系，西安  710048; (2)中国工程物理研究院流体物理研究所，绵阳  621900
Published: December 2020

Semi-insulating GaAs photoconductive semiconductor switch (PCSS) with withstand voltage of 32 kV and peak current of 3.7 kA has been developed. The breakdown mechanism of the PCSS is analyzed. It is shown that the breakdown of PCSS fabricated from indirect band-gap semiconductors is determined mainly by limited conduction of trap filling, but for PCSS's fabricated from materials that exhibit the transferred-electron effect, such as GaAs, breakdown of the PCSS is caused mainly by the negative-resistance-induced electric field enhancement at the anode boundary. Based on the Gunn effect electronics, the breakdown voltage of the semi-insulating GaAs PCSS is calculated, and the calculated results agree with the experimental results.
Improved performance of white polymer light emitting diodes
Authors: Zou Jian-Hua  , Tao Hong  , Wu Hong-Bin  , 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

White polymer light-emitting diodes (WPLEDs) with bilayer structure were fabricated by spin coating method using polymers of different solubilities. The device structure used here is ITO/PEDOT(50nm)/PVK∶PFO-BT∶PFO-DBT(40nm)/PFO(40nm)/Ba(4nm)/Al(120nm)，at the weight ratio of 100∶4∶3 (PVK∶PFO-BT∶PFO-DBT). White fluorescent light emission with CIE coordinates of (0.33, 0.34) is achieved, and the maximal luminance efficiency of 2.4 cd/A and the maximal luminance of 3215 cd/m2 are obtained. By attaching a layer of water-soluble electronic transporting material of PFN to the cathode, the maximal luminance efficiencies increase up to 5.28 cd/A with CIE coordinates kept at (0.34, 0.36), and the device stabitity is also improved.
Influence of in-plane fields on the three kinds of hard domains
Authors: Hu Yun-Zhi  , Sun Hui-Yuan  ,   (1)河北师范大学物理科学与信息工程学院，河北省新型薄膜材料实验室，石家庄  050016; (2)河北师范大学物理科学与信息工程学院，河北省新型薄膜材料实验室，石家庄  050016；科学出版社高等教育出版中心，北京  100717
Published: December 2020

The influence of in-plane field on three kinds of hard domains was studied experimentally by means of direct current bias fields reconstruction. The experiment verifies that VBLs in those three kinds of hard domains collapse gradually under the in-plane field. And the conclusion we obtained that these hard domains have the same range of the critical in-plane field ［H1ip,H2ip］ corrects the previous view that (H1ip)IIDH1ip)IDH1ip)OHB. By revealing that the breakdown of VBLs affected by in-plane field is independent of the rigidity of the hard domains, this paper provides an important clue for interpreting the mechanism of the VBLs' vanishing and a new scheme for exactly measuring the critical in-plane field under which VBLs begin to disappear.
Energy transfer via cooperative upconversion between Er3+ ions in a tellurite glass
Authors: Zhou Ya-Xun  , Dai Shi-Xun  , Zhou Ling  , Xu Tie-Feng  , Nie Qiu-Hua  , Huang Shang-Lian  ,   (1)宁波大学信息科学与工程学院，宁波  315211; (2)重庆大学光电技术及系统教育部重点实验室，重庆  400044; (3)重庆大学光电技术及系统教育部重点实验室，重庆  400044；宁波大学信息科学与工程学院，宁波  315211
Published: December 2020

Erbium-doped tellurite-based glasses with compositions of TeO2-ZnO-Na2O(TZN)and TeO2-ZnO-La2O3(TZL)are prepared, and fluorescence properties of Er3+:4I13/2→4I15/2 transition have been investigated as a function of erbium-doping concentration. It is found that fluorescence intensity decreases evidently with increasing erbium-doping concentration under higher doping, and it is mainly a result of concentration quenching effect in which energy migration takes place due to energy transfer via cooperative upconversion between Er3+ ions when the procedure of removing OH-1 by bubbling oxygen is adopted in melting glass. By fitting the rate equations of population to the normalised fluorescence decay curves, the coefficients of cooperative upconversion are obtained, and the values for the 4I13/2 are estimated to be CTZN=3.27×10-18cm3/s and CTZL=3.01×10-18cm3/s, respectively. Also, the critical concentration and the critical interaction distance are calculated, and the values for the TZN and TZL glasses are QTZN=11.2×1020　cm-3 and QTZL=11.8×1020cm-3, RTZN=0.597nm and RTZL=0.587nm, respectively. Compared with some other glasses reported, the tellurite glass prepared by us has a better rare-earth Er3+ ion solubility and a lower rate of energy transfer via cooperative upconversion, and may serve as good glass host for broadband fiber amplifiers.
Lifetime of a new type of reservoir oxide cathode
Authors: Wang Xiao-Xia  , Liao Xian-Heng  , Luo Ji-Run  , Zhao Qing-Lan  , Zhang Xiao-Wei  ,   中国科学院电子学研究所中国科学院高功率微波源与技术重点实验室，北京  100190
Published: December 2020

The lifetime of a new type of reservoir oxide cathode and a conventional oxide cathode was experimentally studied. Concentrations of Ba in different coating depths of the cathodes were analysed by XPS during the lifetime testing process. The mechanism of the reservoir oxide cathode lifetime was discussed according to the analysis results, the cathode structures and the characteristics of the reservoir emission materials. The results show that the lifetime of the reservoir oxide cathode is about seven times that of the conventional oxide cathode. Ba concentration keeps steady in the depth of cathode coating, which plays an important role in the long lifetime of the reservoir oxide cathode.
Fabrication of Yb3+,Er3+:YAG transparent ceramics and study of its 1.5 μm fluorescence spectrum
Authors: Huang Tong-De  , Jiang Ben-Xue  , Wu Yu-Song  , Li Jiang  , Shi Yun  , Liu Wen-Bin  , Pan Yu-Bai  , Huang Li-Ping  , Guo Jing-Kun  ,   (1)中国科学院上海硅酸盐研究所,上海  200050; (2)中国科学院上海硅酸盐研究所,上海  200050；中国科学院研究生院，北京  100049
Published: December 2020

5at%Yb3+,2at％Er3+:YAG transparent ceramics possessing a high transmittance was sintered at 1760℃ for 30 h by solid-state method and vacuum sintering technique. The sample exhibited pore-free structure and had no secondary phase in the grain boundary and in the grain, as observed in the SEM photograph. The sample's absorption and fluorescent spectra show that the Yb3+ ions have a high absorption coefficient at 940nm. The decay life-time at the 1030nm wavelength is only 0.274 ms and the initial intensity has an ascending tendency in the fluorescent life-time curve at the wavelength range of 1.5 μm, both of which demonstrate the existence of energy transfer from Er3+ ions to Yb3+ ions. The life-time and stimulated emission cross section of electronic transition between some levels were calculated with the intensity parameter Ωλ of Er3+ acquired from Judd-ofelt theory. The experimental results of the spectrum parameters (the emission cross section and fluorescent life-time)of Er3+ ions in the wavelength range of 1.5μm are the same as the results of the Judd-Ofelt theory. The transition between 4I13/2 and 4I15/2 simultaneously has a large stimulated emission cross section, fluorescence ratio and upper level life-time relative to the other energy level transitions of the sample, which makes the laser output of Er,Yb:YAG transparent ceramics in the wavelength range of 1.5 μm, the eye-safe wavelength range, possible.
Mn/PbTe(111) interface behavior studied by photoemission
Authors: Wu Hai-Fei  , Zhang Han-Jie  , Liao Qing  , Lu Yun-Hao  , Si Jian-Xiao  , Li Hai-Yang  , Bao Shi-Ning  , Wu Hui-Zhen  , He Pi-Mo  ,   浙江大学物理系，杭州  310027
Published: December 2020

We performed X-ray photoemission spectroscopy (XPS) investigation on the interface behavior at the Mn/PbTe(111) interface. The measurement shows the drastic changes at atomic level and the Mn/PbTe(111) interface formation. Upon Mn deposition, a new peak component associated with metallic Pb appears in the Pb core-level at low binding energies, and a new peak component related to MnTe compound appears in the Te core-level at high binding energies. These new features become more and more obvious in XPS spectra with increasing Mn thickness, and at the Mn thickness higher than 7 ML (beyond the escape depths of Pb and Te), the substrate features disappear. Upon further deposition of Mn, the intensity of the metallic Pb core level keeps constant, while the intensity of Te 3d core level of MnTe compound decreases with increasing Mn thickness, and finally the Te 3d core level disappears at Mn thickness of about 102 ML. Based on these results, we can conclude that, upon Mn depostion, both Te and Pb segregate to the surface region, the segregated Pb as metallic Pb floats on the top of Mn overlayer, and the segregated Te is bound in the Mn overlayer as MnTe.
Laser pulse control of bridge state electron transfer in heterogeneous structures
Authors: Zhao Hong-Min  , Wang Lu-Xia  ,   (1)北京交通大学理学院物理系，北京  100044; (2)北京科技大学应用科学学院物理系，北京  100083
Published: December 2020

Combined with one-dimensional reduced vibrational model and optimal control theory, the heterogeneous electron transfer in bridge mediated systems is theoretically studied. Laser pulse control of heterogeneous system with single bridge and double parallel bridges are simulated, the the dynamic process and the optimal pulse are analysed. The influence of bridge molecules on the ultrafast electron transfer path is also discussed.
Effect of TiO2 particle size on the properties of electron transport and back-reaction in dye-sensitized solar cells
Authors: Liang Lin-Yun  , Dai Song-Yuan  , Hu Lin-Hua  , Dai Jun  , Liu Wei-Qing  ,   中国科学院等离子体物理研究所太阳能材料与工程研究室,合肥  230031
Published: December 2020

The mechanisms of electron transport and back-reaction kinetics in dye-sensitized solar cell (DSC) were investigated by intensity-modulated photocurrent spectroscopy (IMPS) and intensity-modulated photovoltage spectroscopy (IMVS). The DSCS with three different sizes of TiO2 particles were measured by IMPS/IMVS. The results indicate that the effective diffusion coefficient (Dn) increases along with the increase of particle size, while the electron lifetime (τn) and the electron transit time (τd) decrease with the increase of particle size under different induced-light intensities. The increase of Dn is attributive to the decrease of the film surface area. The decrease of τn is interpreted according to the frequency of electron trapping and de-trapping in defects. The decrease of trap concentration in TiO2 films leads to the decrease of τd.
A false limit in atmospheric radiative transfer and the physics behind it
Authors: Duan Min-Zheng  , Guo Xia  ,   中国科学院大气物理研究所，北京  100029
Published: December 2020

When both the solar and view zenith direction approach horizontal, the reflected radiance at the top of the atmosphere, derived from the plain-parallel atmospheric radiative transfer equation, is different and it depends on the path how the incidence and reflected directions tend to be horizontal. This phenomenon under extreme condition is called limit discontinuity in mathematics. However, the discontinuity of the limits is contradictory to the physical nature of atmospheric radiative transfer and it is obtained by neglecting an implicit physics principles, the Snell's law. The Snell's law must be used in the radiative transfer algorithm for radiance under this extreme condition to avoid obtaining wrong results.
Cognitive radio spectrum assignment based on quantum genetic algorithm
Authors: Zhao Zhi-Jin  , Peng Zhen  , Zheng Shi-Lian  , Xu Shi-Yu  , Lou Cai-Yi  , Yang Xiao-Niu  ,   (1)杭州电子科技大学通信工程学院，杭州  310018; (2)中国电子科技集团公司第36研究所，嘉兴  314033
Published: December 2020

Cognitive radio spectrum assignment based on quantum genetic algorithm is proposed, and simulations are conducted to compare the proposed method with color sensitive graph coloring algorithm. Results show that the proposed method greatly outperforms the color sensitive graph coloring algorithm as it better optimizes network utilization. The proposed method can find the optimal solutions after only several generations, while the relative differences between solutions obtained by color sensitive graph coloring algorithm and the optimal solutions are quite large.
Bielemental random networks
Authors: Chen Hong-Bin  , Fan Ying  , Fang Jin-Qing  , Di Zeng-Ru  ,   (1)北京师范大学系统科学系，北京  100875; (2)华侨大学信息科学与工程学院，厦门  361021; (3)中国原子能科学研究院，北京  102413
Published: December 2020

On the basic of bipartite networks，bielemental networks are defined as networks which include two kinds of vertexes，and connections between different kinds of vertexes are permitted. In this article，a bielemental random network model is founded，and the structure of the bielemental random network is studied. Small-world effect can be found in such model，furthermore，the average shortest path length is smaller than that of unipartite random networks. And the proportion of the numbers of two kinds of vertexes is a very important factor.
The mean first-passage time for an asymmetric bistable system driven by two colored noises
Authors: Wang Bing  , Wu Xiu-Qing  , Shao Ji-Hong  ,   安徽理工大学理学院，淮南  232001
Published: December 2020

By means of an extended colored-noise approximation，we investigated the effects of asymmetry of the potential and noises on the mean first-passage time T+（xs1→xs2） and T-（xs2→xs1） in two opposite directions in an asymmetric bistable system （here xs1 and xs2 are stable points of the asymmetric bistable system）. Numerical results show that T+（xs1→xs2） decreases with increasing of τ1 （the correlation time of multiplicative noise） and τ2 （the correlation time of additive noise）. T-（xs2→xs1） increases with increasing of τ1 and τ2. The curves of T+（xs1→xs2） versus λ and T-（xs2→xs1） versus λ are single-peaked. T+（xs1→xs2） will increase when r increases，but T-（xs2→xs1） will decrease when r increases.
Chaotic time series prediction based on fuzzy boundary modular neural networks
Authors: Ma Qian-Li  , Zheng Qi-Lun  , Peng Hong  , Qin Jiang-Wei  ,   华南理工大学计算机科学与工程学院，广州  510640
Published: December 2020

A fuzzy boundary modular neural network （FBMNN） is proposed for the chaotic time series prediction. First，the reconstructed phase space is divided into several subspaces and the divided points are evaluated by genetic algorithms. Then a fuzzy membership function is defined and the fuzzy boundary is set on the border according to the fuzzy membership. Through this fuzzy treatment，the jumping problem of the predicted data near the divided points are solved. Finally the data points of each module and its fuzzy boundary are input to a recurrent neural network for training and the output predicted points are synthesized by a synthesis forecast module. The effectiveness of FBMNN is evaluated by using three benchmark chaotic time series data sets：the Mackey-Glass series，Lorenz series，and Henon series. The simulation results show that FBMNN improves the performance of chaotic time series prediction.
The coupled feedback control of spatiotemporal chaos based on the flocking algorithms
Authors: Yang Chao-Yu  , Tang Guo-Ning  ,   广西师范大学物理与电子工程学院,桂林  541004
Published: December 2020

Spatiotemporal chaos control in a one-dimensional nonlinear drift-wave equation is considered. We propose a method of coupled feedback to suppress the spatiotemporal chaos of the drift-wave,based on the flocking algorithms. By using real agents and virtual agents as our target, we show numerically that the spatiotemporal chaos can be controlled to a regular state if appropriate control strength is chosen. The physical mechanism is analyzed based on the correlation coefficient
Fuzzy control of chaos in permanent magnet synchronous motor with parameter uncertainties
Authors: Li Dong  , Zhang Xiao-Hong  , Yang Dan  , Wang Shi-Long  ,   (1)重庆大学机械传动国家重点实验室，重庆  400030; (2)重庆大学软件学院，重庆  400030; (3)重庆大学数理学院，重庆  400030
Published: December 2020

The permanent magnet synchronous motor （PMSMs） may have chaotic behaviors under certain working conditions, especially for uncertain values of parameters，which threatens its secure and stable operation. Hence，it is important to study methods of controlling or suppressing chaos in PMSMs. In this paper，the Takagi-Sugeno fuzzy control model for PMSMs with parameter uncertainties is established via the Takagi-Sugen modeling method. Based on the new model，the control conditions of asymptotical stability for PMSMs with parameter uncertainties have been derived by Lyapunov method and matrix analysis. An illustrative example is also given to show the effectiveness of our results. Compared with the curently available results，the obtained results exhibit some advantage.
A new four-dimensional hyperchaotic system and its circuit simulation
Authors: Tang Liang-Rui  , Li Jing  , Fan Bing  ,   华北电力大学电气与电子工程学院，北京  102206
Published: December 2020

A new four-dimensional chaotic system is reported in this paper. Basic dynamic properties of the new system are investigated via theoretical analysis，numerical simulation，Lyapunov exponent，Lyapunov dimension and Poincare diagrams. Finally the chaotic circuit is designed and realized by the Multisim software. It confirms that the chaotic system is different from the exisiting chaotic systems and is a new hyperchaotic system.
Chaos synchronization of a complex network with different nodes
Authors: Lü Ling  , Zhang Chao  ,   辽宁师范大学物理与电子技术学院，大连  116029
Published: December 2020

A method of chaos synchronization of a complex network with different nodes is proposed. The complex network is constructed by chaos systems with diverse structures. The coupling functions of the connected nodes of the complex network are identified based on Lyapunov stability theory. The Rssler system，Coullet system and Lorenz system are taken as network nodes of the complex network in the paper. Simulation results show that a stable synchronization is obtained in whole complex network. The method can achieve synchronization of the networks with nodes of any chaotic systems，and the number of the node does not affect the stability of the whole complex network，therefore，it has a universal application.
Effect of system gain on optical chaotic communications systems
Authors: Liu Hui-Jie  , Feng Jiu-Chao  ,   (1)华南理工大学电子与信息学院，广州  510641; (2)华南理工大学电子与信息学院，广州  510641；东莞理工学院电子工程系，东莞  523808
Published: December 2020

The chaotic communications systems with optical feedback lasers in strong injection and open-loop configuration are studied in this paper. The quantity relationship between gain and injection factor is obtained by numerical calculation. The demodulators performances under the conditions of whether the gain is used to adjust the output of the receiver are compared. The result indicates that the recovered message is more close to the original message by using the adjusted subtraction demodulation method. It is proved that message rate has no effect on gain by testing sine signals with different rates. Further，the gain is shown to be independent of message type and encryption mechanism by testing digital signals at 0.2?Gbit/s rate.
Multi-fractal identification of the fluctuation of silicon content in blast furnace hot metal based on multi-resolution analysis
Authors: Luo Shi-Hua  , Zeng Jiu-Sun  ,   (1)江西财经大学信息管理学院,南昌  330013; (2)浙江大学数学系，系统优化技术研究所,杭州  310027
Published: December 2020

With data of silicon content in hot metal collected respectively from No. 6 blast furnace of Baotou Steel, No. 7 blast furnace of Handan Steel and No.1 blast furnace of Laiwu Steel as sample spaces, quantitative analysis was employed to identify the multi-fractal characteristics of silicon content series. The long term trend of silicon content series was removed by performing multi-resolution analysis and the multi-fractal characteristics of the remaining part was analyzed. Comprehensive and quantitative details of the partial fluctuant singularity and fluctuant singularity at different levels are displayed through computation of generalized Hurst index, scaling function and multi-fractal spectrum. Simulation results proved that the fluctuation of silicon content series from 3 different blast furnaces showed significant multi-fractal characteristics, which is far from sufficient to be described by a single Hurst index or box dimension.
The cooperative effect of a colloidal particle driven by a periodic signal in a harmonic potential
Authors: Qin Li  , Bao Jing-Dong  ,   北京师范大学物理系，北京  100875
Published: December 2020

For a colloidal particle in a harmonic potential driven by a periodic signal，we study its thermodynamic behavior and obtain the exact expressions of the effective temperature and dissipated work by solving the corresponding Langevin equation. The results show that due to the cooperative effect of the potential，the signal and the noise，the energy of the environment can be transferred to the colloidal particle through the stirring action of the periodic driving force，which makes the effective temperature of the system increase greatly. Under the condition of dynamical resonance，the dissipated work also reaches its maximum.
Hourglass-shaped X-ray compound refractive lens made by back-mask exposure technology
Authors: Zhu Yan-Qing  , Liang Jing-Qiu  , Liang Zhong-Zhu  , Huang Xin-Hua  , Le Zi-Chun  , Yi Fu-Ting  , Hou Feng-Jie  , Huang Wan-Xia  , Dong Wen  , Wang Wei-Biao  , Wang Zhi-Li  , Cui Nai-Di  ,   (1)浙江工业大学，杭州  310032; (2)中国科学院长春光学精密机械与物理研究所应用光学国家重点实验室，长春  130033; (3)中国科学院长春光学精密机械与物理研究所应用光学国家重点实验室，长春  130033；中国科学院研究生院，北京  100049; (4)中国科学院高能物理研究所，北京  100049
Published: December 2020

Using back-mask exposure technology，the hourglass-shaped X-ray compound refractive lens （XCRL） was made. Firstly，the theory of the refractive focusing of the hourglass-shaped XCRL was analyzed. Then the hourglass-shaped XCRL was manufactured using back-mask exposure technology for the first time，which avoids two-time masking and reduces the transfer times of the figure. The refractive focusing performance of the lens was tested with 10?keV monochromatic X-ray. The experimental results indicated that it has good focusing performance in one dimension, which is in general coincident with the calculated results.
The influences of the finite nuclear size effects on the energy levels and wavefunctions of hydrogen-like ions
Authors: Zheng Shu-Dong  , Li Bo-Wen  , Li Ji-Guang  , Dong Chen-Zhong  , Yuan Wen-Yuan  ,   (1)西北师范大学物理与电子工程学院,兰州  730070; (2)西北师范大学物理与电子工程学院,兰州  730070；青海大学基础部,西宁  810016
Published: December 2020

Based on the relativistic theory, the wavefunctions and low-lying levels of highly charged states of hydrogen-like ions for the shells n=1—3 were calculated using different nuclear models——point-like nuclear and Fermi nuclear models with two parameters, respectively. The influence of the finite nuclear size on wavefunctions and level energies were analysed. Furthermore, a fitting formula related to nuclear parameter a and c in Fermi nuclear model for finite nuclear effects on the atomic level energy is deduced. The mutual influence between the relativistic effect and the finite nuclear size effects were discussed. It is found that there is a strong coupling between relativistic effect and finite nuclear size effects for high-Z elements.
A controllable electrostatic double-well trap for cold polar molecules
Authors: Xu Xue-Yan  , Chen Hai-Bo  , Yin Jian-Ping  ,   (1)巢湖学院物理系，巢湖  238000；华东师范大学物理系，光谱学与波谱学国家重点实验室，上海  200062; (2)华东师范大学物理系，光谱学与波谱学国家重点实验室，上海  200062
Published: December 2020

We propose a novel controllable electrostatic double-well trap scheme by using two charged ring wires and two parallel transparent electrodes. The spatial distributions of the electrostatic field from the above charged wires and the charged plates are calculated. We also analyze the advantages of the proposed scheme, and discuss the loading process of cold molecules from a cold molecular beam into our trap. Our study shows that our controllable double-well trap is not only convenient to trap, manipulate and control cold polar molecules in the weak-field-seeking states, but also has the potential applications in molecule optics field，such as molecular interference, molecular entanglement, and molecular collisions, even to study the molecular BEC in the double-well trap, and so on.
An application of digital signals in an atom Chip
Authors: Shi Tao  , Yan Hui  , Yang Guo-Qing  , Wang Jin  , Zhan Ming-Sheng  ,   (1)中国科学院武汉物理与数学研究所波谱与原子分子物理国家重点实验室,武汉  430071；中国科学院冷原子物理中心,武汉  430071; (2)中国科学院武汉物理与数学研究所波谱与原子分子物理国家重点实验室,武汉  430071；中国科学院冷原子物理中心,武汉  430071；中国科学院研究生院,北京  100080
Published: December 2020

Digital signals （square wave） are superpositions of many frequency components in frequency domain. We analyze and calculate the coupling potentials between the atom and the frequency components respectively, and demonstrate that the atomic trapping adiabatic potential can be generated by taking into account the total coupling potential. An application scheme of the digital signal in an atom chip is proposed.
Fluorescence weakening due to radiation trapping in a high density cold-atom cloud
Authors: Zhou Shu-Yu  , Xu Zhen  , Qu Qiu-Zhi  , Zhou Shan-Yu  , Liu Liang  , Wang Yu-Zhu  ,   中国科学院上海光学精密机械研究所量子光学重点实验室,上海  201800
Published: December 2020

We have measured the change of fluorescence from cold 87Rb atoms after magnetic field of the magneto-optic trap is turn off. A rise in fluorescence within several tens of milliseconds was observed. Analyzing this phenomenon in connection with the experimental conditions, we found that incoherent pumping field due to radiation trapping in the high density cold-atom cloud was the reason of fluorescence weakening under tight confinement by the magneto-optic trap. We have also performed a simple numerical simulation, which indicated that the calculations agree with experimental results only when the effect of frequency redistribution of scattered light is taken into account.
Lie symmetry and conserved quantity of Appell equation for a Chetaev’s type constrained mechanical system
Authors: Jia Li-Qun  , Cui Jin-Chao  , Zhang Yao-Yu  , Luo Shao-Kai  ,   (1)江南大学理学院,无锡  214122; (2)平顶山学院电气信息工程学院,平顶山  467002; (3)浙江理工大学数学力学与数学物理研究所,杭州  310018
Published: December 2020

Lie symmetry of Appell equation and conserved quantity deduced directly by Lie symmetry for a Chetaev's type constrained mechanical system are investigated. The relations between Lagrange function and A function are analyzed. A general approach of studying conserved quantity deduced by Lie symmetry of Appell equation for a Chetaev's type constrained mechanical system is discussed. The definition and the criterion of Lie symmetry of Appell equations under the infinitesimal transformations of groups are given. The structural equation of Lie symmetry and the expression of conserved quantity deduced directly by Lie symmetry are obtained. An example is given to illustrate the application of the results.
Derivation of the material parameters for regular N-sided polygonal cylindrical cloak and the invisibility verification
Authors: Wu Qun  , Zhang Kuang  , Meng Fan-Yi  , Li Le-Wei  ,   (1)哈尔滨工业大学电子与信息技术研究院，哈尔滨  150001; (2)哈尔滨工业大学电子与信息技术研究院，哈尔滨  150001；新加坡国立大学电气与计算机工程系，新加坡
Published: December 2020

General expressions of constitutive tensors of the N-sided regular polygonal cylindrical cloaks are derived based on the coordinate transformation theory, then there are some full-wave simulations of the cloaks.The results of full-wave simulations validate the general expressions of constitutive tensors we derived. Furthermore, factors that degrade the cloaks invisibility are analyzed.
Investigation on the characteristics of electromagnetic scattering from 2-D fBm rough surface of layered medium
Authors: Ren Xin-Cheng  , Guo Li-Xin  ,   (1)西安电子科技大学理学院,西安  710071; (2)西安电子科技大学理学院,西安  710071；延安大学物理与电子信息学院,延安  716000
Published: December 2020

The electromagnetic scattering from the rough surface of layered medium with plane wave incidence is investigated. A 2-D fBm fractal rough surface is used to simulate the natural rough surface of layered medium, and the formulae of the scattering coefficient of the 2-D fBm fractal dielectric rough surface of layered medium with the plane wave incidence is derived by using the small perturbation method in association with the power spectrum density of 2-D fBm fractal rough surface. The angular distribution of the bistatic-scattering coefficient of HH polarization are obtained by numerical computation, the influence of fractal dimension, the permittivity of substrate medium, the permittivity and the mean layer thickness of intermediate medium, the surface roughness parameters and the frequency of the incident wave on the bistatic-scattering coefficient is discussed. The fractal characteristics, the basic characteristics, the zonal characteristics and the characteristics with varying frequency of the scattering coefficient from 2-D fBm fractal rough surface are obtained.
Monte-Carlo study of radiography with laser-produced proton beam
Authors: Teng Jian  , Hong Wei  , Zhao Zong-Qing  , Wu Shun-Chao  , Qin Xiao-Zun  , He Ying-Ling  , Gu Yu-Qiu  , Ding Yong-Kun  ,   (1)中国工程物理研究院激光聚变研究中心，绵阳  621900; (2)中国工程物理研究院激光聚变研究中心，绵阳  621900；国防科技大学物理系，长沙  410072; (3)中国工程物理研究院激光聚变研究中心，绵阳  621900；清华大学工程物理系，北京  100084
Published: December 2020

Radiography using ultra-short laser-produced proton beams is a development of traditional proton radiography. According to the characteristic of laser-produced proton beam, using FLUKA Monte-Carlo program, the quantitative simulation of proton radiography is studied. From the simulation of three typical cases （half-plane target and ladder target, hohlraum with a plastic ball in it,and detection of magnetic field with mesh method）, the main physical factors that effect the proton radiography are discussed. The advantage of radiography of laser-produced protons, such as high sensitivity to boundary, high spatial resolution, and high sensitivity to magnetic field, is demonstrated.
Propagation and spatiotemporal coupling of iso-diffraction ultra-short pulsed Hermite Gaussian beams in free space
Authors: Lu Da-Quan  , Hu Wei  , Qian Lie-Jia  , Fan Dian-Yuan  ,   (1)复旦大学光科学与工程系先进光子学材料与器件国家重点实验室，上海  200433; (2)华南师范大学光子信息技术广东省高校重点实验室，广州  510631; (3)华南师范大学光子信息技术广东省高校重点实验室，广州  510631；复旦大学光科学与工程系先进光子学材料与器件国家重点实验室，上海  200433
Published: December 2020

A family of solutions called iso-diffraction ultra-short pulsed Hermite Gaussian beams （UPHGB） are obtained based on the paraxial propagation equation. The propagation of UPHGB is investigated in detail. The examples shows that: the nonuniformlly distributed group velocity causes the time delay at the beam periphery, which in turn induces the deviation of the transverse distribution from the Hermite Gaussian function. In propagation, the number of pulse polarity inverions varies with the order of the UPHGB. And this phenomenon originates in the difference between the group velocity and the phase velocity in UPHGB.
Fabrication of LaF3: Er, Yb nanoparticle doped organic-inorganic hydrid material waveguide amplifier and its properties
Authors: Zhang Dan  , Wang Zhao-Ming  , Wang Yan-Shuang  , Bo Shu-Hui  , Zhen Zhen  , Zhang Da-Ming  ,   (1)吉林大学应用技术学院，长春  130012; (2)集成光电子学国家重点联合实验室吉林大学实验区，吉林大学电子科学与工程学院，长春  130012; (3)中国科学院理化技术研究所，北京  100080
Published: December 2020

LaF3: Er, Yb nanoparticles doped organic-inorganic hydrid material waveguide amplifier is fabricated. The optical gain and upconversion in the waveguide are studied. The upconversion emission bands at 405,520,544 and 650?nm are assigned to 2H9/2→4I15/2，2H11/2→4I15/2，4S3/2→4I15/2 and 4F9/2→4I15/2 transitions, respectively. The possible upconversion mechanism of Er3+ in this material was analyzed. A 155 dB/cm relative gain was observed when pumped by a 976?nm laser at 160 mW power.
Study on the effects of carrier transport and parasitic parameters on the modulation response of tunnel regenerated vertical-cavity surface-emitting lasers with double active regions
Authors: Wang Tong-Xi  , Guan Bao-Lu  , Guo Xia  , Shen Guang-Di  ,   北京工业大学,北京市光电子技术实验室,北京  100124
Published: December 2020

A rate equation model of multi-quantum wells and multi-active regions were presented. The effects of photon density and the carrier capture-escape-tunnel time on the frequency response of single active region vertical-cavity surface-emitting Laser （VCSEL） and tunnel-regenerated VCSEL with two active regions were simulated by the small signal analysis. The result of simulation shows that the modulate bandwidth of tunnel-regenerated VCSEL with two active regions is larger than that with single active region under the same drive current, then its causes are discussed. Moreover, we simulate the frequency response of the parasitic circuit of tunnel-regenerated internal-contact oxide-confined VCSEL with two active regions after analyzing its parasitic parameters.