bluuebunny/crossref_metadata_2025 huggingface dataset:
The nonlinear sensing property and electric mechanism of carbon humidity-sensitive membranes
Authors: Chen Huan  , Peng Zhen-Kang  , Fu Gang  ,   广州大学物理与电子工程学院，广州  510006
Published: December 2020

The nonlinear sensing property and electric mechanism of carbon humidity-sensitive membranes under investigation were manufactured by using hydroxyethyl cellulose （HEC）, carbon black （CB） and humidizer sorbitol. Microstructures examined by scanning electronic microscopy （SEM） show that, an effective carbon black electric network in humidity-sensing membrane would make the membrane’s resistance to have strong nonlinear property near 80%RH; so that the amount of 2wt% carbon black is in the proximity of the electric percolation threshold. The voltage-current characteristic suggested that the nonlinear sensing property and electric mechanism of the carbon humidity membranes are closely related. Particularly, impedance spectroscopy of sample at 92%RH was made up by two semi-circular arcs and a straight tail near 45° angle. The membrane′s equivalent circuit was three RC circuits in series that corresponds to the contributions of the carbon bulk resistance, CB-grain-boundary resistance and electrode contact resistance, respectively.
Separating of dislocation ring at finite temperature
Authors: Lu Guo  , Fang Bu-Qing  , Zhang Guang-Cai  , Xu Ai-Guo  ,   (1)北京应用物理与计算数学研究所实验室,北京  100088; (2)中国工程物理研究院研究生部,北京  100088; (3)中国工程物理研究院研究生部,北京  100088；北京应用物理与计算数学研究所实验室,北京  100088; (4)中国矿业大学,北京  100083
Published: December 2020

We constructed a partial dislocation ring with Burgers vector b=［112］/6 in the glide plane （111） of copper crystal, and studied its self-contraction process in the temperature range, from 0 to 350 K by using molecular dynamics simulations. The results reveal that, at zero temperature the dislocation ring cannot pass the Peierls-Ｎabarro potential barrier, so its migrating velocity is zero; below 50 K, the screw part and the edge part of the dislocation have nearly the same migrating velocity. With the increasing of temperature, the edge dislocation migrates more quickly than the screw dislocation. At a higher temperature, the dislocation core becomes wider, consequently, it may contain more complex internal structures and becomes easier for separating. At the same time, local stress gradient within the mixed dislocation zone becomes steeper and results in the generation of four partial dislocation rings. The four new dislocation rings first grow with time under the influence of original dislocation ring. When the original ring finally disappears, the newly created rings begin to shrink and finally disappear. This is a new dislocation source, different from the Frank-Read，L or double cross-slip type.
Influence of penetrating V-pits on leakage current of GaN based p-i-n UV detector
Authors: Zhang Shuang  , Zhao De-Gang  , Liu Zong-Shun  , Zhu Jian-Jun  , Zhang Shu-Ming  , Wang Yu-Tian  , Duan Li-Hong  , Liu Wen-Bao  , Jiang De-Sheng  , Yang Hui  ,   中国科学院半导体研究所集成光电子国家重点联合实验室,北京  100083
Published: December 2020

The leakage mechanism of GaN-based p-i-n （p-AlGaN/i-GaN/n-GaN） UV detector has been investigated. With the same dislocation density, devices made from material with higher density of V-pits on surface produce larger leakage current. SEM images show that some V-pits penetrate into i-GaN layer, sometimes even the n-GaN layer. If p-ohmic contact metal （Ni/Au） deposits in the V-pits, Schottky contact would be formed at the interface of metal and i-GaN, or form ohmic contact at the interface of metal and n-GaN. The existence of parallel Schottky junction and ohmic contact resistance enhances the leakage current greatly.
Thickness dependence of microstructure for La0.9Sr0.1MnO3/Si films determined by micro-Raman spectroscopy
Authors: Liu Xue-Qin  , Han Guo-Jian  , Huang Chun-Kui  , Lan Wei  ,   兰州大学物理科学与技术学院，兰州  730000
Published: December 2020

La0.9Sr0.1MnO3 films on Si （100） substrate of different thickness were prepared by sol-gel routine, and the microstructure of LSMO/Si was studied by XRD and confocal micro Raman spectroscopy. Both XRD and Raman results show different structures in LSMO films of different thickness. There are two strong peaks around 490 cm-1and 600 cm-1 that is characteristic of Jahn-Teller distortion in spectra and characteristic peak of rhombohedral structure of the film with thickness of 90 nm, which show the coexistence of two phases. Lattice constants of LSMO film vary with film thickness. Lattice constants vary as film thickness increases, which is because the tilting angle of MnO6 octahedron and the bond length of Mn-O increase as film thickness increases. Raman spectra of 532 nm-laser and 325　nm-laser show, that there are two phases existing in LSMO/Si film, namely the phase in LSMO/Si interface, and the rhombohedral phase in the surface.
Optical absorbance of diamond doped with nitrogen and the nitrogen concentration analysis
Authors: Liang Zhong-Zhu  , Liang Jing-Qiu  , Zheng Na  , Jia Xiao-Peng  , Li Gui-Ju  ,   (1)吉林大学超硬材料国家重点实验室，长春  130012; (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)中国科学院东北地理与农业生态研究所，长春  130012
Published: December 2020

The combination of outstanding properties, such as high thermal conductivity, high refractive index, extreme hardness, radiation resisting, and high insulation, makes diamond an ideal material for optical application under extreme requirements. The relationship between the optical absorbance of diamond doped with nitrogen and the nitrogen concentration were studied. The calculation method of nitrogen concentration used in this study was a modification of the typical calculation method. The high nitrogen concentration diamond was synthesized in Fe80Ni20-carbon and sodium azide system. The absorbant intensity of diamond increases in 800—1400 cm-1 range. The nitrogen concentration in diamond increases with the increasing contents of NaN3. The color of diamond changes with the increase of NaN3 content, in the order of green, dark green and black. The diamond synthesized with addition of NaN3 contains nitrogen exceeding 1450 ppm which is much higher than the normal diamond. The optical transmission of diamond decreases with the increase of nitrogen concentration. The diamond with nitrogen doping can be used as optical material with better absorbance and many physical characters at some wavenumber.
Scheme for doubling the number of wings in hyperchaotic attractors
Authors: Hu Guo-Si  ,   烟台大学光电信息科学技术学院，烟台  264005
Published: December 2020

The construction methods for designing multi-wing attractors are rarely mentioned little. With the application of coordinate translation, mirror mapping and hysteresis switching to an existing five-dimensional hyperchaotic system, we can double the number of wings and a four-wing attractor is realized. If similar operations have been applied to the system n-1 times, a 2n-wing attractor can be constructed. A simple circuit implementation was designed for doubling the number of wings in attractors. On the basis of preserving the hyperchaotic property of resulting system, the complexity of attractor is enhanced and it is more suitable for use in secure encryption communication.
Multiscale base-scale entropy analysis of heart rate variability
Authors: Huang Xiao-Lin  , Cui Sheng-Zhong  , Ning Xin-Bao  , Bian Chun-Hua  ,   (1)南京大学电子科学与工程系近代声学教育部重点实验室，生物医学电子工程研究所，南京  210093; (2)南京医科大学生理学系，南京  210029
Published: December 2020

Multiscale base-scale entropy （MBE） is used to analyze heart beat interval series of both congestive heart failure （CHF） sufferers and the healthy people. The results indicate that, in contrast to the higher base-scale entropy（BE） value in short time scale, the data of CHF sufferers have actually lower BE value compared with those of the healthy people in long time scale. This supports the view that CHF patients’ heart beats are more random in short time scale due to impaired cardiac dynamic system, but are not versatile enough in long time scale to adapt to external impacts. More importantly, we found that δ, a parameter in MBE analysis, can be used to distinguish effectively the CHF patients from the healthy, which is proved in analysis of a database containing 72 healthy people and 44 CHF sufferers.
Bottom quark pair production in γγ collision
Authors: Huang Jin-Shu  , Luo Peng-Hui  , Lu Gong-Ru  ,   (1)河南师范大学物理与信息工程学院,新乡  453007; (2)河南师范大学物理与信息工程学院,新乡  453007；南阳理工学院电子与电气工程系,南阳  473005; (3)河南师范大学物理与信息工程学院,新乡  453007；南阳师范学院物理与电子工程学院,南阳  473061
Published: December 2020

We study the Yukawa corrections to the γγ→b cross section in the topcolor assisted technicolor models at the photon-photon colliders. We find that, for the favorable parameters, the relative corrections from pseudo-Goldstone bosons give out a 3.17%—5.90% decrement of the cross section from the tree level when /{s/}2=500 GeV, the total relative corrections are significantly larger than the corresponding corrections in the standard model, the general two Higgs doublet model and the minimal supersymmetric standard model. So the observation of the correction to the γγ→b process at the International Linear Colliders is certainly the clue to the standard model and new physics.
Modulation of feedback strength to enhance the security of chaos optical communication system
Authors: Guo Dong-Ming  , Yang Ling-Zhen  , Wang An-Bang  , Zhang Xiu-Juan  , Wang Yun-Cai  ,   太原理工大学物理系，太原  030024
Published: December 2020

There is a high tolerance on parameters mismatch between transmitter and receiver in the chaos communication system based on injection locking synchronization，so to a certain extent，the information security has been reduced. We propose the synchronous modulation of feedback strength to improve the system security. The change of signal extraction quality after modulation is studied numerically，and the effects of modulation rate detuning and modulation delay time on signal extraction are analyzed too. The research results indicate that the synchronization of the original system is destroyed and the bit error rate increases by two orders of magnitude when the transmitter feedback strength is modulated. The information can not be recovered unless the receiver uses the same modulation. Furthermore，the results also show that high quality information could be obtained when rate detuning and delay time are in the range of ±5 MHz and ±0.1 times the modulation cycles, respectively. All of these prove that modulating the feedback strength can enhance the security of chaos communication efficiently.
Mechanical and electronic properties of TiO2 nanotubes
Authors: Lin Feng  , Li Zuan-Yi  , Wang Shan-Ying  ,   清华大学物理系，北京  100084
Published: December 2020

The structure, stability, Youngs modulus and electronic band structures of lepidocrocite-type and anatase-type TiO2 nanotubes were investigated using density functional theory calculation. It was found that the anatase-type nanotubes were energetically more favorable than lepidocrocite-type nanotubes when the diameter of nanotube is small, whereas the lepidocrocite-type nanotubes were energetically more favorable when the diameter of nanotube was large. Youngs modulus of TiO2 nanotubes is calculated. The results obtained show that all TiO2 nanotubes have relatively good mechanical properties, and lepidocrocite nanotubes are stronger than anatase nanotubes. Interestingly, it was found that the electronic band structures of TiO2 nanotubes are influenced by the tubular chirality. Lepidocrocite （0, n） and anatase （n, 0） nanotubes are of indirect band gap type, whereas lepidocroctie （n, 0） and anatase （0, n） nanotubes have direct band gaps.
Terahertz transmission properties of transparent conducting molybdenum-doped ZnO films
Authors: Wu Chen-Guo  , Shen Jie  , Li Dong  , Ma Guo-Hong  ,   (1)复旦大学材料科学系，上海  200433; (2)上海大学物理系，上海  200444
Published: December 2020

With direct current reactive magnetron sputtering method，transparent conducting molybdenum-doped ZnO （ZMO） thin films with different carrier concentration on glass substrate were fabricated by monitoring oxygen partial pressure. The dielectric responses of the ZMO films are characterized with terahertz time-domain spectroscopy. Frequency dependent conductivity，power absorption，and refractive index are obtained，and the experimental results can be well reproduced with classic Drude model. Our results reveal that，by adjusting the carrier concentration of ZMO film，the conducting ZMO film can serve as broadband antireflection coatings for substrates and optics in terahertz frequency range.
Possible probe on the momentum dependent interaction in the equation of state of nuclear matter
Authors: Guo Wen-Jun  , Liu Jian-Ye  ,   (1)Physics Department of Tianshui Normal University, Tianshui 741000, China, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China, Center of Theoretical Nuclear Physics, National Laboratory of Heavy Ion Accelerator,Lanzhou 730000,; (2)Science College University of Shanghai for Science and Technology, Shanghai 200093, China
Published: December 2020

The effects of momentum dependent interaction on the kinetic energy spectrum of the neutron-proton ratiorb(Ek)in the equation of state of nuclear matter was investigated.We found that the kinetic energy spectrum of the neutron-proton ratio rb(Ek) depends sensitively on the momentum dependent interaction and weakly on the in-medium nucleon-nucleon cross section and symmetry potential so that the rb(Ek) is a sensitive physical probe for extracting the information of momentum dependent interaction in the heavy ion collisions. At the same time, the comparing investigate between rb(Ek) for the neutron-rich collision system and the same mass stable collision system gives a important judgment for extracting the information of momentum dependent interaction in the heavy ion collisions.
The flow field heat distribution of inorganic liquid laser under oblique pumping
Authors: Wei Yong-Tao  , Ma Zai-Ru  , Song Ying-Song  , Feng Guo-Ying  , Li Mi  , Hu Tao  , Zhang Yu-Ming  ,   (1)College of Architecture and Environmental, Sichuan University, Chengdu 610065, China; (2)College of Electronics and Information Engineering, Sichuan University, Chengdu 610064, China; (3)College of Electronics and Information Engineering, Sichuan University, Chengdu 610064, China, Institute of Applied Physics, Xihua University, Chengdu 610039, China; (4)Institute of Applied Electronics, China Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

The multi-segment liquid laser system connected in series and obliquely pumped by LD can have significantly improved laser beam quality and higher output power. A flow-heat-solid interaction model for calculating the temperature distribution in the sub-gain section is established, which is focused on the flow, heat transfer and coupling in sub-gain section. We performed the numerical simulation of transient flow-field-heat distribution by way of the finite element method. The method proposed precludes the influence of the inaccurate film coefficient on the calculation results, the film coefficient is no longer a prerequisite, but a result of the calculation. Our method provides a new effective way to assess and control the flow-field-heat distribution which is affected by the flow channel shape, flow rate, absorption coefficient and other factors. Numerical results show that the film coefficient is a function of spatial location. Flow and heat transfer effieciency decreases with increasing velocity. When the laser medium is flowing, the temperature distribution and temperature gradient distribution are similar and are complementary to the film coefficient distribution, the maximum temperature and temperature gradient appears in the sharp corner downstream the flow.
Wave localization in one-dimensional periodic-on-average disordered system composed of single-negative metamaterials
Authors: Liu Dong-Mei  , Han Peng  ,   Laboratory of Quantum Information Technology, South China Normal University, Guangzhou 510006, China
Published: December 2020

By using the transfer-matrix method,we study the Anderson localization behavior in one-dimensional periodic-on-average disordered system composed of two different single-negative(SNG) metamaterials. Non-dispersive and dipersive models have been studied respectively. It was found that the disorder has great effect on waves with frequency in the pass band of the corresponding periodic structure. However,inside the gap,the effect can be almost ignored. These features are different from those we ever found in the random single-negative system. The main reason of the difference should be the number of the interfaces between two kinds of single negative metamateirals,which should be the basic mechanism of the wave propagation in systems made of single negative metamaterials. In periodic-on-average disordered systems,the number of the interface is the same as that in periodic one. However,there is an obvious decrease in random systems,which will have a great effect on the ability of wave transport,leading to small localization length. In the case of a dispersive model,it has been proved that the randomness has no effect on the wave propagation with frequency at the center of the gap. Especially,this special point becomes a delocalization point when the ratio of effective optical thickness of two single negative materials equals one. The results facilitates further understanding of the wave transport mechanism in systems composed of metamaterials.
Numerical and experimental study on coherent combining of double cladding multi-core photonic crystal fiber
Authors: Han Wei-Tao  , Hou Lan-Tian  , Geng Peng-Cheng  ,   (1)Institute of Infrared Optical Fibers & Sensors, Yanshan University, Qinhuangdao 066004, China; (2)Institute of Infrared Optical Fibers & Sensors, Yanshan University, Qinhuangdao 066004, China, State Key Laboratory of Metastable Materials Science & Technology,  Qinhuangdao 066004,  China
Published: December 2020

The supermodel mode field characteristics of double cladding multi-core photonic crystal fiber were analyzed with coupled-mode theory. Through the phase adjustment of evanescent wave on 7 beams of light, one can realize the coherent combination, by which the laser brightness is greatly enhanced. We analyzed and measured the coherent power density of the light emitted from the double cladding multi-core photonic crystal fiber using coherent combination theory, and provide the theoretical and experimental basis for this multi-core photonic crystal fiber to achieve self-coherent synthesis.
First-principles study on chemisorption of Cl on γ-TiAl(111) surface
Authors: Wu Xiao-Xia  , Wang Qian-En  , Wang Fu-He  , Zhou Yun-Song  ,   Department of Physics, Capital Normal University, Beijing 100048, China
Published: December 2020

The chemisorption of Cl atoms on the γ-TiAl(111) surface is investigated by density functional theory. The calculated results show that the more stable sites for Cl atoms adsorption are the surface face-centred cubic (fcc) sites and the surface hexagonal close-packed (hcp) sites. When the coverage of Cl is less than 1 monolayer (ML), Cl atoms prefer the adsorption site with more Ti atoms as its nearest neighbors on the surface layer. From the analysis of the electronic structures, it can be found that the bonds formed by Cl and metal atoms are mainly ionic and directional. When Cl and O atoms are co-adsorbed on γ-TiAl(111) surface, both of them prefer the fcc and hcp sites. As a result, there is a competition between them. Furthermore, the adsorption energy per oxygen atom is increased by the adsorption of Cl atoms, which indicates that interactions between oxgen and metal atoms are weakened by the adsorption of Cl atoms on γ-TiAl(111) surface. This may be one of the reasons why the oxidation resistance of γ-TiAl can be improved by chlorine treatment.
Impedance analysis of BaFe0.4Sn0.6O3/BaBiO3 composite negative temperature coefficient ceramics
Authors: Yuan Chang-Lai  , Liu Xin-Yu  , Yang Yun  , Xu Ji-Wen  , Gu Yan  ,   Key Laboratory of Information Materials of Guangxi, Guilin University of Electronic Technology, Guilin 541004, China
Published: December 2020

The BaFe0.4Sn0.6O3/BaBiO3 composite negative temperature coefficient (NTC) thermistor ceramics were prepared by conventional solid-state reaction method. The raw materials used are composed of conductive BaBiO3 phase and high resistive BaFe0.4Sn0.6O3 phase. The conductive mechanism of thermistor ceramics before and after the percolation threshold (containing 12 mol% of BaBiO3), is investigated by impedance analysis. For compositions with 5 mol%—8 mol% of BaBiO3, the contribution to the conductivity is mainly due to the grain boundary (Rb), grain (Rg), and grain shell (Rs) existing in the BaFe0.4Sn0.6O3. In the range of 10 mol%—12 mol% of BaBiO3, the grain (Rbg) and grain boundary resistance (Rbb) corresponding to the BaFe0.4Sn0.6O3 melted with BaBiO3 in composite ceramic, are also main factor governing the resistance magnitude, the values of which are lower than the other main sources like Rb, Rg, and Rs. For composition x=0.15, the values of Rbb and Rbg are higher than that of Rb, Rg and Rs. For BaBiO3 contents around 20 mol%, the resistance is mainly determined by the values of Rbb and Rbg. In addition to the electrode-specimen interface, all of the components in composite ceramic show NTC feature. The NTC composite ceramics with different BaBiO3 contents show nonideal Debye-like behavior, and the conduction mechanism of the composite ceramics is of the localizing type.
Non-smooth bifurcation analysis of a piecewise linear chaotic circuit
Authors: Ji Ying  , Bi Qin-Sheng  ,   Faculty of Science, Jiangsu University, Zhenjiang 212013, China
Published: December 2020

The dynamics of a nonlinear capacitor circuit is investigated in this paper. The symmetric periodic solution and the chaotic attractor can be observed in numerical simulations. Furthermore, the generalized Jacobian matrix at the non-smooth boundaries is introduced to explore the non-smooth bifurcation mechanism for the periodic solutions. Discontinuous bifurcation in the combination of the Hopf bifurcation and the turning point bifurcation occurs at the non-smooth boundaries. Here, the Hopf bifurcation may result in a new frequency, which leads to periodic oscillation. With the variation of the parameter, the periodic symmetric solution oscillates more quickly, which can also be explained through non-smooth bifurcation, and the conclusion accord well with the numerical results.
The effects of exit position and internal layout of classroom on evacuation efficiency
Authors: Zhu Kong-Jin  , Yang Li-Zhong  ,   State Key Laboratory of Fire Science, University of Science and Technology of Hefei 230027, China
Published: December 2020

On the basis of the previous cellular automaton evacuation model, we modify the method of calculating the pedestrians transition probability with considering the effect of aisle region in the classroom-like buildings, and analyze the difference among evcuation efficiencies imduced by different exit positions and different layoutt inside classrooms. The results demonstrate that it is very beneficial when the exit faces the aisle, that it is useful to set up exit on the side of the classroom compared with exit which is on the edge of the facing classroom in order to reduce the change in direction of pedestrian movement,that the exit situated at the central position in the front of classroom is the most efficient, however, is unrealistic; in addition, when the classroom is designed to have a side exit, the aisle is necessarily close to the exit side of the wall; when the total capacity of the classroom is fixed, we should give a priority to the design of aisle distribution, rather than the design of the arrangement of chairs and tables; the number of aisles is more significant to affect the evacuation efficiency than the width of a single aisle, the larger the number arisles is, the higher the evacuation efficiency will be. This paper is expected to be able to make suggestions for the design of internal layout and exit position of the classroom, as well as the design of the distribution of grandstand seats and aisles in similar buildings, such as theaters, stadiums, etc.
Theoretical calculations of X-ray spectra of Au plasma
Authors: Yi You-Gen  , Tang Jing-Wu  , Huang Du-Zhi  ,   (1)Physics School of Science and Technology, Central South University, Changsha 410083; (2)School of Physics, Hunan University of Science and Technology, Xiangtan 411201
Published: December 2020

By using a detailed configuration accounting method in the collisional radiative equilibrium model, and Cowans relativistic atomic structure code with respect to ionic averaged configurations and Hartree-Fock-Slater potential, we solve the rate equations for populations of all ionic and level populations of all excited states, in which main consider main atomic dynamic processes in a non-local thermodynamic equilibrium plasma can be considered, thereby obtaining the ionic populations and energy level populations and the ionic charge stage distribution and the average charge for Au. We also simulate and calculate the X-ray emission spectra of Au 5f—3d transition arrays. The calculated results are in good agreement with the experimental data for a well-characterized highly ionized Au plasma.
Stereodynamics study of O+ +H2 reaction and its isotopic variants
Authors: Liu Xin-Guo  , Sun Hai-Zhu  , Liu Hui-Rong  , Zhang Qing-Gang  ,   College of Physics and Electronics, Shandong Normal University, Jinan 250014, China
Published: December 2020

The stereodynamics in the chemical reaction O+ +H2and its isotopic variants at a collision energy of 20 kcal /mol are investigated by using the quasi-classical trajectory (QCT) method on RODRIGO surface. The correlated k- j', k-k'-j' angular distributions, polarization-dependent differential cross sections (PDDCSs) and the product rotational alignment are discussed in detail. The calculations indicate that the stereodynamic properties of the reactions of O+ +H2→OH+ +H、O+ +DH→OD+ +H and O+ +TH→OT++H are sensitive to the mass factor and the repulsive energy of diatomic molecule.
Slow highly charged ions induced electron emission from clean Si surfaces
Authors: Wang Jian-Guo  , Xu Zhong-Feng  , Zhao Yong-Tao  , Wang Yu-Yu  , Li De-Hui  , Zhao Di  , Xiao Guo-Qing  ,   (1)Department of Applied Physics, MOE Key Laboratory for Non-equilibrium Synthesis and Modulation of Condensed Matter, Xi’an Jiaotong University, Xi,an 710049, China; (2)Department of Applied Physics, MOE Key Laboratory for Non-equilibrium Synthesis and Modulation of Condensed Matter, Xi’an Jiaotong University, Xi,an 710049, China;Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China; (3)Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China
Published: December 2020

The electron emission yields from the interaction of slow highly charged ions (SHCI)He2+,O2+and Ne2+ with clean Si surface are measured separately. It is found that electron emission yield γ increases proportionally to projectile kinetic energy EP/MP ranging from 0.75 keV/u to 10.5 keV/u (i.e. 3.8×105 m/s≤vP≤ 1.42×106 m/s), and it is higher for heavy ions (O2+and Ne2+) than for light ion (He2+). For O2+and Ne2+, γ increases with ZP decreasing in our energy range, and it shows quite different from the result for higher projectile kinetic energy. After calculating the stopping power by using TRIM 2006, it is found that the fraction of secondary electrons induced by recoil atoms increases significantly at lower projectile energy, thereby leads to the differences in γ for heavy ions O2+and Ne2+between lower and higher projectile kinetic energy.
Study on structure and stability of AlnC and AlnC+(n=1—8)
Authors: Feng Xuan-Qi  , Jiang Zhen-Yi  , Feng Xue-Hong  ,   (1)Modern Physics Institute, Northwest University, Xi’an 710069, China; (2)Physics Department, Northwest University, Xi’an 710069, China; (3)Science School, Xi’an Jiaotong University, Xi’an 710049, China
Published: December 2020

Comparing the results of AlC cluster, computed by 7 methods of density functional theory (DFT), with experimental data, we choose B3lyp/6-311G(d) to optimize the structures and analyse the frequencies of AlnC and AlnC+(n=1—8) clusters. All ground states and metastable states of AlnC and AlnC+ clusters are obtained. Our calculations reveal that there exists a transition from planar to spacial structures with the number of Al atoms increasing. Planar structures is mostly triangle and spacial structure is primarily triangular prism cage structure. Of the high symmetry clusters, only one of neutral and cation has a stable structure. Compared with various kinds of AlnC and AlAlnC+(n=1—8) clusters under study, Al2C and Al5C are stable.
Photo-induced insulator-metal transition of silicon-based VO2 nanofilm by THz time domain spectroscopy
Authors: Wang Chang-Lei  , Tian Zhen  , Xing Qi-Rong  , Gu Jian-Qiang  , Liu Feng  , Hu Ming-Lie  , Chai Lu  , Wang Qing-Yue  ,   (1)Ultrafast Laser Laboratory, College of Precision Instrument and Optoelectronics Engineering, Tianjin University, Tianjin 300072, China; (2)Ultrafast Laser Laboratory, College of Precision Instrument and Optoelectronics Engineering, Tianjin University, Tianjin 300072, China;Center for Terahertz Waves, College of Precision Instrument and Optoelectronics Engineering, Tianjin University, Tianjin
Published: December 2020

The photo-induced insulator-metal transition for silicon-based VO2 nanofilm is studied by THz time-domain spectroscopy (THz-TDS). Obvious variations of THz ray transmittance are observed before and after the CW laser beam exciting, and the conductivity of metallic-phased VO2 film in the THz region is calculated in the thin film approximation. According to the measured results, the metallic-phased VO2 film is characterized equivalently with Drude’s model, and complex conductivity, dielectric function and refractive index are acquired by the model. As an examination on the equivalent Drude model, numerical simulation based on the finite integral method in time domain is carried out. The results show that they are in good agreement with the experimental results. This work provides a reference for the study on phase transition of VO2 nanofilm and its application in the THz region.
Passive phase locking of fiber laser based on spatial filtering
Authors: Xue Yu-Hao  , Zhou Jun  , He Bing  , Qi Yun-Feng  , Li Zhen  , Liu Chi  ,   (1)Shanghai Institute of Optics and Fine Mechanics, The Chinese Academy of Sciences, Shanghai 201800,China;Graduate School of the Chinese Academy of Sciences,Beijing 100039,China; (2)Shanghai Institute of Optics and Fine Mechanics, The Chinese Academy of Sciences, Shanghai 201800,China;Graduate School of the Chinese Academy of Sciences,Beijing 100039,China;Graduate School of the Chinese Academy of Sciences,Beijing 100039,China
Published: December 2020

Coherent beam combination of Yb-doped fiber laser array is studied theoretically and experimentally by spatial filtering to passive phase locking. The principle of optical feedback phase locking based on spatial filtering is analyzed, and the relations of Strehl ratio in far field to wavelength and spectrum bandwidth are studied. The coherent beam combination of four Yb-doped fiber amplifier array is achieved experimentally, and stable interference pattern is obtained. The Strehl ratio in far field is 0.77. In the output spectrum, the bandwidth of single longitudinal mode is about 9.1 GHz consistent with the theoretical calculation.
The damage effect and mechanism of the bipolar transistor induced by the intense electromagnetic pulse
Authors: Chai Chang-Chun  , Xi Xiao-Wen  , Ren Xing-Rong  , Yang Yin-Tang  , Ma Zhen-Yang  ,   School of Microelectronics,Xidian University,Key Lab of Ministry of Education for Wide Band-GapSemiconductor Materials and Devices,Xi'an 710071,China
Published: December 2020

A study of the internal damage process and mechanism of the typical n+-p-n-n+ structure bipolar transistor induced by the intense electromagnetic pulse (EMP) is carried out in this paper from the variation analysis of the distribution of the electric field,the current density and the temperature. Research shows that the damage position of the bipolar transistor is different with the different magnitude of the injecting voltage,when the magnitude of the injecting voltage is low the damage will appear firstly near the collector region under the center of the emitter region,and when the magnitude of the injecting voltage is sufficiently high the damage will appear firstly at the edge of the base near the emitter due to the breakdown of the PIN structure composed of the base-epitaxial layer-collector. Adopting the data analysis software,the relation equation between the device damage power P and the pulse width T under different injecting voltage is obtained. Owing to the variety of the device damage energy,it is demonstrated that the empirical formulas of the intense electromagnetic pulse P=AT-1 (A is a constant) is modified to P=AT-1.4 for the bipolar transistor.
Spherical superlens analysed by dyadic Green’s function
Authors: Huo Bing-Zhong  , Yuan Jing-He  , Shang Ying  , Meng Chun-Ning  ,   (1)CAS Key Laboratory of Molecular Nanostructure and Nanotechnology, Institute of Chemistry,Chinese Academy of Sciences,Beijing 100190,China; (2)Institute of Modern Optics,Nankai University,Tianjin 300071,China; (3)School of Science and Technology for Opto-electronic Information, Yantai University Yantai 264005,China
Published: December 2020

In this paper, we carry out the numerical simulation of spherical superlens by the Dyadic Green’s function method, and we prove the sub-wave length imaging capability of spherical superlens. Dyadic Green’s function method is an effective method and a systematic theory of dealing with the problem of electromagnetic fields, which makes up the deficiencies in coordinate transformation method. Compared with the flat lens, the spherical superlens have several advantages, including the finiteness cross-section, and ability in lensing with magnification or demagnification, high resolution, two-dimensional imaging, etc.
A new method of detecting abrupt dynamic change based on rescaled range analysis
Authors: Deng Bei-Sheng  , He Wen-Ping  , Cheng Hai-Ying  , Wu Qiong  , Zhang Wen  ,   (1)Department of Atmospheric Sciences, Lanzhou University, Lanzhou 730000,China;Beijing Meteorological Bureau, Beijing 100089, China; (2)Department of Basic Course, Yancheng Institute of Technology, Yancheng 224002, China; (3)National Climate Center, China Meteorological Administration, Beijing 100081, China; (4)National Satellite Meteorological Center, China Meteorological Administration, Beijing 100081, China; (5)Tongda College, Nanjing University of Post and Telecommunications, Nanjing 210003
Published: December 2020

A new method is proposed in this paper—moving cut data-rescaled range analysis (MC-R/S). Tests on the correlated time series suggest that the MC-R/S can accurately detect the time-instants of abrupt change, and the MC-R/S results almost do not depend on the length of subseries and are less affected by noises. So, MC-R/S is suitable to detecting an abrupt dynamic change in those time series exhibiting correlations, and can very well make up the deficiency of moving detrended fluctuation analysis (MDFA).
Effect of global warming on law of record-breaking high temperature
Authors: Zong Xu-Ping  , Li Ming-Hui  , Xiong Kai-Guo  , Hu Jing-Guo  ,   (1)College of Mathematical Science,Yangzhou University,Yangzhou 225002,China; (2)College of Physics Science and Technology,Yangzhou University,Yangzhou 225002,China
Published: December 2020

Statistical characteristic of daily temperature series (1954—2004) of Xiamen station is analyzed by using Gaussian and skew distribution functions, and then the future probable trend of record temperature events (RBTE) is also simulated by using Monte-Carlo(MC) methods based on the Gaussian and skew distribution functions, respectively. Results show that the statistical property of nearly 50a daily observation temperature data in June of Xiamen station is more consistent with that obtained from the skew function. However, the theoretical study shows that the skew function and Gaussian function have the same limit of convergence, i.e. the Gumbel distribution function. The results also show that the MC simulation based on the skew distribution with global warming background can reveal the future probable extreme events well, and the Xiamen's daily temperature distribution of June in the next 10 a is predicted. The global warming background can lead the occurrence probabilities of high-temperature record-breaking event and the average daily temperature to increase. In addition, based on the observed date in China, the spatial temperature distribution of the occurrence with the max probability over China in coming 10 years is also presented.
Implicit solitary wave solutions for a class of nonlinear dispersive Boussinesq equation
Authors: Bi Qin-Sheng  , Jiang Bo  , Han Xiu-Jing  ,   (1)College of Mathematics and Physics, Jiangsu Teachers University of Technology, Changzhou 213001, China;Faculty of Science, Jiangsu University, Zhenjiang 212013, China; (2)Faculty of Science, Jiangsu University, Zhenjiang 212013, China
Published: December 2020

By applying the bifurcation method of dynamical systems to a class of nonlinear dispersive Boussinesq equations, the analytic expressions of implicit solitary wave solutions are obtained under different parameter conditions. Numerical simulations are given to show the correctness of our results.
Entanglement properties of two-atom inside cavities controlled by manipulating the atom outside the cavity
Authors: Lu Dao-Ming  ,   Department of Electronic Engineering, Wuyi University, Wuyishan 354300, China
Published: December 2020

Considering three two-level atoms initially in the W state, then two of them are placed into two initially empty cavities respectively and made resonantly interacted. The two-atom entanglement evolution inside cavities is investigated. The effects of rotational manipulation and state-selective measurement of the atoms outside the cavities on the two-atom entanglement evolution inside cavities are discussed. The results obtained using the numerical method show that the two-atom entanglement inside cavities is controlled by manipulating the atom outside the cavity.
Lattice Boltzmann simulation of surface hydrophobicity with nano-structure
Authors: Shi Juan  , Li Hua-Bing  , Wang Wen-Xia  , Qiu Bing  ,   (1)School of Information and Communication, Guilin University of Electronic Technology, Guilin 541004, China; (2)School of Material Science and Engineering, Guilin University of Electronic Technology, Guilin 541004, China
Published: December 2020

To study the surface hydrophobicity of solid materials with the lattice Boltzmann method, a rough surface is approximately treated as simple periodic rectangular, saw-tooth and semicircular protrusion structures separately. A two-phase lattice Boltzmann model is used to simulate the change of surface hydrophobicity by calculating the contact angle of a droplet on the rough surface. Finally, the fluid flow in a nano-channel with rough walls is studied.
Influence of temperature on the Bose condensation of photons and excitons in optic microcavity
Authors: Cheng Zheng-Fu  , Long Xiao-Xia  , Zheng Rui-Lun  ,   Department of Physics, Chongqing University of Arts and Sience, Chongqing 402160, China
Published: December 2020

In this paper, an exciton-photon model is created in an optic microcavity, and then in Bose condensation (BC), the variations of chemical potential range and number density of particles with temperature and position are studied in cases: constant width and varying width. Taking a semiconductor optic microcavity GaAs as example, the influence of temperature on BC is analyzed. The result shows that the range of chemical potential is related to dielectric function and microcavity width, while the number densities of photons and excitons and the sum of both particle numbers are related not only to them but also to temperature. The theoretical temperature of BC of GaAs is close to the experimental value. The densities of photons and excitons are almost equal, and their distributions are restricted to r=0 when BC occurs. With the reduction of temperature the number densities of both particles increase and their distributions expand, and the number of photons is more than that of excitons no matter how the width of optic microcavity changes.
Study on border collision and bifurcation of two-dimensional piecewise smooth systems in current mode controlled Buck converter
Authors: Zhang Bo  , Xie Fan  , Yang Ru  ,   (1)College of Electric Power, South China University of Technology, Guangzhou 510640, China; (2)School of Physics and Electronic Engineering, Guangzhou University, Guangzhou 510006, China
Published: December 2020

Border collision bifurcations have received much attention in recent years. A class of piecewise smooth maps with two border and three zones is derived to describe the dynamics of a current-programmed Buck converter operating in a discontinuous mode. The numerical simulation is carried out and the bifurcation diagrams with the reference current as a parameter are obtained. Then, a concrete analysis of the stable existence condition of the fixed point is made, and the structure of bifurcation diagrams and a change in operation mode of the converter at the border collision point are studied. Finally, simulation and experimental results show that the theoretical analysis is correct.
Intermediate-scale instability in one-cycle controlled Cuk power factor correction converter
Authors: Zhang Yuan  , Zhang Hao  , Ma Xi-Kui  ,   State Key Laboratory of Electrical Insulation and Power Equipment, School of Electrical Engineering, Xi’an Jiaotong University, Xi’an 710049, China
Published: December 2020

Based on the autonomous character of one-cycle control, the average model of one-cycle controlled Cuk power factor correction converter can be derived. Subsequently, the approximate analytical expressions of periodic solutions are obtained by using the harmonic balance method. Furthermore, through analyzing the changing trend of Floquet multipliers, the location and the type of the first bifurcation point are predicted. Thus, the intrinsic mechanism of such an instability can also be explained. The results show that the intermediate-scale instability is due to the loss of stability of periodic solutions, which is named the Neimark-Sacker bifurcation in the circuit system. Finally, experimental results are presented for verification purpose. Our work has revealed the salient feature of the intermediate-scale instability, and provided a theoretical basis for facilitating design of the converter.
Experimental study of vacuum backpressure on the discharge characteristics of a Hall thruster
Authors: E Peng  , Duan Ping  , Wei Li-Qiu  , Bai De-Yu  , Jiang Bin-Hao  , Xu Dian-Guo  ,   (1)College of Physics Science and Technology, Dalian University, Dalian 116622, China; (2)Department of Electrical Engineering, Harbin Institute of Tchnology, Harbin 150001, China
Published: December 2020

It is found that the vacuum backpressure affects the flow of background gas into a Hall thruster channel. The flow of background gas can affect the ionization of propellants and the conductivity of electrons, and thereby affect the physical process and discharge characteristic of Hall thrusters. In order to investigate these effects, the atomic and the ionic emission spectra in the discharge channel and the ions energy distribution are measured under different vacuum backpressures. The experimental results indicate that the increase of vacuum backpressure can reduce the electron temperature and ionization efficiency of propellants and a new ionization region appears near exit plane in the channel; and moreover, it is found that the new ionization region penetrates into the channel more deeply under the higher vacuum backpressure case.
Study of stimulated scattering in laser-plasma-interaction by linear theory
Authors: Xiang Jiang  , Zheng Chun-Yang  , Liu Zhan-Jun  ,   (1)Institute of Applied Physics and Computational Mathematics, Beijing 100094, China; (2)Institute of Applied Physics and Computational Mathematics, Beijing 100094, China;Center for Applied Physics and Technology, Peking University, Beijing 100871, China; (3)Institute of Applied Physics and Computational Mathematics, Beijing 100094, China;Center for Applied Physics and Technology, Peking University, Beijing 100872, China
Published: December 2020

The linear theory and the post process program LIP are developed to describe the stimulated scattering in laser-plasma-interaction. The two damping rates, especially the collision damping rate, are included in the program LIP. The effects of the laser intensity and electron temperature are investigated in an ignition scale plasma. The importance of the collision damping is revealed, and it is found that the growth rate of the stimulated scattering is effectively reduced by the collision damping when the plasma density is close to one-quarter of critical density. Whereas, the electron temperature is responsible for the increase of the growth rate on the specific density scale. The results may provide the reference for the ignition design in reducing the reflectivity.
Structure and thermodynamic properties of Ni based superconductive material EuNi2Si2
Authors: Qian Ping  , Shen Jiang  , Wang Yu-Jie  , Zhou Jun-Min  ,   (1)Department of Physics and Electronic Engineering, Zhoukou Normal University, Zhoukou 466000, China; (2)Institute of Applied Physics, University of Science and Technology Beijing, Beijing 100083, China
Published: December 2020

We investigate the structure stability, stretching, compressing, shearing, random shifting and X-ray diffraction of Ni based superconductive material EuNi2Si2 with different space group numbers based on inversed interatomic potentials obtained with Chen-Mbius lattice-inversion technique. It is found that the space group number of 139 has the lowest binding energy and the structure is the most stable. Furthermore, the phonon density and the thermodynamic properties of the stable structure are calculated and discussed. The phonon density of states shows that the low frequency range is dominated by the rare-earth element Eu with larger atomic mass. While with frequency increasing, the Si atoms with smaller atomic mass become more and more prominent. For the specific heat and the vibrational entropy, Eu and Ni contribute more in the low temperature range, Si becomes more and more prominent with temperature increasing.
Effects of AlGaN layer parameter on ultraviolet response of n+-GaN/i-AlxGa1-xN/n+-GaN structure ultraviolet-infrared photodetector
Authors: Deng Yi  , Zhao De-Gang  , Wu Liang-Liang  , Liu Zong-Shun  , Zhu Jian-Jun  , Jiang De-Sheng  , Zhang Shu-Ming  , Liang Jun-Wu  ,   State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors,Chinese Academy of Sciences, Beijing 100083, China
Published: December 2020

We have investigated the effect of AlGaN layer parameter on the ultraviolet response of n+-GaN/i-AlxGa1－xN/n+-GaN structure ultraviolet-infrared photodetector and its physical mechanism. Through the simulation, it is found that the decrease of AlGaN background concentration has a positive effect on device’s ultraviolet quantum efficiency. When AlGaN layer background concentration cannot be reduced, the decrease of its thickness can ensure the efficiency. Besides, interfical state should be minimized during materials growth and device fabrication. In addition, small reverse bias voltage can greatly increase ultraviolet quantum efficiency. All these phenomena may be mainly attributed to the existence of the back-to-back heterojunction and the opposite electrical field. It is suggested that we need to adjust structural parameters to obtain high quantum efficiency according to the materials quality in device design.