bluuebunny/crossref_metadata_2025 huggingface dataset:
Density functional study on hydrogenation and non-hydrogenation graphene nanoribbon
Authors: Yuan Jian-Mei  , Mao Yu-Liang  ,   Faculty of Mathematics and Computational Science, Xiangtan University, Xiangtan 411105, China;,   Faculty of Material, Photoelectronic and Physics, Xiangtan University, Xiangtan 411105, China
Published: December 2020

Based on density functional theory and first-principles method, we investigate the structure and the electronic property of graphene nanoribbion with width N=8 and with or without hydrogen saturation on their edge. Our results show that the carbon atoms on the edge of armchair graphene nanoribbon without the hydrogen saturation are bonded together by triple bonding, which is stronger and more sensitive than that in the case of hydrogen saturation. This type of graphene nanoribbon can serve as a kind of basic material for nano-sensor. Our band structure calculations indicate that both armchair and zigzag nanoribbions are of semiconductor possessing an energy gap. Furthermore, the energy gap of nanoribbon without hydrogen saturation is larger than that with hydrogen saturation, which implies that hydrogen saturation has distinct decoration to the property of the nanoribbon. By the calculation of the paramagnetism, ferromagnetism and anti-ferromagnetism states of the zigzag graphene nanoribbon, we find that anti-ferromagnetism state is the most stable among them, and its magnetism on the edge is strongest, which is suitable for the application in spinelectronics.
Influence of electron correlation on Au ions
Authors: Hu Feng  , Yang Jia-Min  , Wang Chuan-Ke  , Zhang Ji-Yan  , Jiang Gang  , Zhu Zheng-He  ,   Research Center of Laser Fusion, CAEP, Mianyang 621900, China;,   Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, China
Published: December 2020

We present a comprehensive theoretical study of atomic characteristics of nine isoelectron sequences of gold ions in a broad range of wavelengths and transitions. The calculation is performed by the multiconfiguration Dirac-Fock(MCDF) method. The valence-valence, the core-valence and the core-core correlations are also considered. The calculated values including core-valence correlation are found to be consistent very well with other theoretical and experimental values. We believe that our calculated values can guide experimentalists in identifying the fine-structure levels in their future work.
Macroscopic effects of high-order harmonic and isolated attosecond pulse generation driven by two-color laser field
Authors: Lu Ying-Ying  , Zeng Zhi-Nan  , Zheng Ying-Hui  , Zou Pu  , Liu Can-Dong  , Gong Cheng  , Li Ru-Xin  , Xu Zhi-Zhan  ,   Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800,China
Published: December 2020

The macroscopic effects of high-order harmonic and attosecond pulse generation driven by two-color laser field are numerically investigated by three-dimensional propagation equation. It is shown that when the 6fs/800nm and 21.3fs/400 laser pulses are focused into gas medium, a broadband supercontinuum can be generated in the plateau by adjusting the time delay between two driven pulses, the position of the entrance of gas medium, the beam waist of driving pulses and the gas pressure. A highly synchronous isolated attosecond pulse can be generated by directly filtering out the harmonics from 420—540 eV in the supercontinuum, which facilitates the experimental implementation for the isolated attosecond pulse generation by two-color scheme.
Wave packet dynamics of the photodetachment ofH- near a metal surface
Authors: Wang Shan-Shan  , Wang De-Hua  , Huang Kai-Yun  , Tang Tian-Tian  ,   College of Physics, Ludong University, Yantai 264025, China
Published: December 2020

The wave packet dynamics of the photodetachment of H- near metal surface is studied by using the wave packet evolution and the autocorrelation function. The results show that the evolution and the revival structure of the detached electron depend not only on the ion-surface distance, but also on pulse width and initial pulse momentum. Therefore, we can control the wave packet dynamics of H- near a metal surface by changing the ion-surface distance and the parameter of the pulse laser. Besides, the electronic image state lifetime can also affect the wave packet evolution and the autocorrelation function. We find that with considering the electronic state lifetime,the amplitude of the quantum probability density decreases gradually with time,the whole wave packet structure has a significant attenuation and the lifetime can weaken the interference phenomenon in the process of wave packet evolution. Through the research on the autocorrelation function of electronic wave packet, we find that the wave packet exhibits a good revival structure without considering the lifetime of the state lifetime; however, with considering the lifetime of the state lifetime, the wave packet periodically collapses and expands with time,but after a period of time, the revival structure disappears. We hope that our theoretical study will provide some references for the experimental research of wave packet dynamics of negative ion near surfaces.
Theoretical study on structural and electronic properties of WnNim(n+m=8) clusters
Authors: Zhang Xiu-Rong  , Li Yang  , Yang Xing  ,   School of Mathematics and Physics, Jiangsu University of Science and Technology, Zhenjiang 212003, China;,   School of Materials Science and Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003, China
Published: December 2020

The possible equilibrium geometries of WnNim(n+m=8) clusters are optimized by using the density functional theory at the B3LYP/LANL2DZ level. For the ground state structures, the average binding energy, the wiberg bond index(WBI), the magnetism and the natural bond orbital(NBO) method are analyzed. The calculated results show that with the increase of the W atom number, the cluster becomes more stable. The strength in WBI is in the following order: W-WW-NiNi-Ni. When n5, the WnNim(n+m=8) clusters include the basic structure of Wn cluster. The magnetic moments of WnNim(n+m=8) clusters are quenched at n=5 and 6.Inside W and Ni atoms, the hybrid phenomenon happens, owing to the charge transfer. And the charge transfer also occurs between W and Ni atoms, thereby forming a strong chemical bond between W and Ni.
A novel method to calculate transient response of thin-wire structure above the layered lossy half-space
Authors: Wei Bing  , He Qiong  , Li Jie  , Ge De-Biao  , Guo Li-Xin  ,   Department of Physics, Xidian University, Xi’an 710071, China
Published: December 2020

A novel hybrid method combining time domain integral equation(TDIE) with finite difference time domain(FDTD) is proposed to calculate transient response of thin wire structure above a layered lossy half-space. The time domain reflections of electromagnetic waves from layered half-space are obtained by one-dimensional FDTD method. Then, transient response of thin-wire induced by two excitation sources (incident wave and reflected wave) is achieved by employing the TDIE. The computed results illustrate the feasibility and high efficiency of the presented scheme.
Characteristics of spontaneous emission from a two-level atom in a very high Q cavity
Authors: Chen Xiang  , Mi Xian-Wu  ,   College of Physics Science and Information Engineering Ji Shou University, Jishou 416000, China
Published: December 2020

In this paper we investigate a coupled system of an initially excited two-level atom coupled to a monomode cavity,and compute spontaneous emission spectrum and mean population density emitted by the atom and the cavity using the quantum theory that accounts for theoretical derviation and numerical calculation.The spectra emitted separately by the atom and the cavity in of strong coupling region are dramatically different from those in weak coupling region at resonance.The cavity spectrum line splitting in the strong coupling region,however,a hole exists in the atomic spectrum in the weak coupling region.We study systematically the emission spectra when the atom and the cavity are detuned,and the results show that if the cavity linewidth is much smaller than the atomic linewidth(good cavity regime),photons are emitted at the cavity frequency even if the atom and the cavity are strongly detuned,and provide theoretic foundation for the apparently puzzling feature observed in the recent experiment.In this paper we computate the atomic and the cavity mean population densities each as a function of time and their relation to the luminous intensity, and offer a new insight into civity induced transparency effect.
Temperature dependent Raman spectra and micro-structure study of hexagonal MgTiO3 crystal
Authors: Wang Li-Hong  , You Jing-Lin  , Wang Yuan-Yuan  , Zheng Shao-Bo  , Simon Patrick  , Hou Min  , Ji Zi-Fang  ,   School of Materials Science and Engineering, Shanghai University, Shanghai 200072, China;,   CNRS UPR3079, Conditions Extrêmes et Matériaux - Haute Température et Irradiation, CEMHTI, 45071 Orléans Cedex 2, et Université d'Orléans, 45067 Orléans Cedex 2, Fran
Published: December 2020

Hexagonal MgTiO3 crystal powder is prepared by solid-phase sintering method and characterized by X-ray diffraction method. Temperature dependent crystal cell parameters (2931473 K) are deduced from the results of in-situ X-ray diffraction measurement with temperature increasing. In-situ Raman spectra are recorded (2931623 K) at various temperatures and all the vibrational modes were assigned with the aid of theoretical calculation of first principles. It is demonstrated that temperature dependent Raman spectra are sensitive and can show the delicate variations of different bond lengths and angles between various atoms of local structure. But the relationship between Raman shift and bond length and angle can be independent of temperature. Those observed Raman vibrational bands being wider and overlapped with the increasing temperature reveals the enhanced amplitude of atomic instantaneous movement, which leads atoms to diffuse more heavily and the stability of the crystal to decrease, although MgTiO3 remains hexagonal crystal type.
Properties of infrasonic wave nonlinear propagation in the inhomogeneous moving atmosphere
Authors: Lü Jun  , Zhao Zheng-Yu  , Zhou Chen  ,   School of Electronic Information, Wuhan University, Wuhan 430079, China
Published: December 2020

A difference wave equation is obtained by discretizing a nonlinear acoustic wave equation in atmosphere in the second-order miniterm approximation based on the finite-difference time-domain method. And the pulsed infrasonic wave radiated by a linear array vertical or oblique propagation in moving inhomogeneous atmosphere is numerical simulated in the two-dimensional space, and sound pressure distribution after the different propagation times is investigated in the Wuhan(114 ∶20E, 30 ∶37N) of China and the initial time UT=29000s of summer and winter. The atmospheric inhomogeneity caused by the change of temperature and density, and the atmospheric motion caused by the presence of wind is considered by using the Msise00 and HWM93 models. The pressure difference pr obtained by subtracting no-windy pressure from the windy-pressure in above two seasons indicates that the wind has more influence on the sound field in the infrasonic propagation. The distribution waveform of pr is dependent on season because the actual acoustic velocity depends on season and propagation distance; The influence of wind on the nonlinear propagation is bigger than on the linear propagation.
Analysis of Lamb waves propagation in functional gradient materials using Taylor expansion method
Authors: Hong Ke  , Yuan Ling  , Shen Zhong-Hua  , Ni Xiao-Wu  ,   School of Science, Nanjing University of Science and Technology, Nanjing 210094, China
Published: December 2020

The technology of ultrasound can be used to evaluate properties of functionally graded materials(FGMs). Because of the inhomogeneity of the FGM properties, distribution function is used to describe the FGM elastic constant and density which are assumed to vary in the direction of the thickness. Taylor expansion method is used to solve Lamb wave propagation problems in FGMs, in which the distribution function is an arbitrary function. Phase velocity dispersion curves for Lamb waves in iron-based alumina FGMs are obtained by using an extension of the Legendre polynomial approach, and the effects of the gradient variation of iron-based alumina FGMs properties on Lamb wave propagation characteristics are discussed in detail. The conclusion could be useful for inversing elastic constant and density, which are varied along the thickness direction, of FGMs.
Research on localization of the source of cyclostationary sound field
Authors: Chen Zhi-Min  , Zhu Hai-Chao  , Mao Rong-Fu  ,   Institute of Noise and Vibration, Naval University of Engineering, Wuhan 430033, China
Published: December 2020

The conventional planar near-field acoustic holography technology cannot exactly refecact the modulation characteristics of cyclostationary sound field radiated from the rotating machineries,and the spurious energy distribution of sidebands exists in its hologram. When the cyclic spectral density (CSD), instead of the energy spectrum of sound pressure is adopted as a reconstructed physical quantity, the modulating wave and carrier wave components of the cyclostationary sound field can be extracted exactly. Focusing on the complicated nature of calculation and the accuracy of feature extracting, the CSD gathering slice method is proposed, and the effect of the additive white noise on the reconstruction is analyzed. The results of the simulation and experiments show that the method has the better anti-noise performance and sound source can be localized exactly.
Spatially-resolved measurement of conductivity of plasma single filament generated by femtosecond laser
Authors: Guo Kai-Min  , Gao Xun  , Xue Nian-Liang  , Zhao Zhen-Ming  , Li Hai-Jun  , Lu Yi  , Lin Jing-Quan  ,   School of Science, Changchun University of Science and Technology, Changchun 130022, China;,   School of Physical Science and Technology, Baotou Teachers College, Baotou 014030, China
Published: December 2020

Electric conductivity and high voltage breakdown threshold of single plasma filament generated by femtosecond laser are spatio resolved measured. The results show that the resistance of the single filament is in a range of 280630 kcm after eliminating the contact resistance, and the breakdown threshold can be reduced down to ~50% of the original value in air. Furthermore, the variations of resistance and discharge threshold follow the same trend as that for the same part filament. The relation between breakdown threshold and resistance of the single filament is established.
Magnetoelectric heating in the ECR plasma
Authors: Shen Wu-Lin  , Ma Zhi-Bin  , Tan Bi-Song  , Wu Jun  , Wang Jian-Hua  ,   School of Material Science and Engineering, Key Laboratory of Plasma Chemical and Advanced Materials of Hubei Province, Wuhan Institute of Technology, Wuhan 430073, China
Published: December 2020

The magnetoelectric heating is investigated on an ECR plasma device. The ion temperatures are measured by ion sensitive probe (ISP) before and after magnetoelectric heating. The influences of bias voltage of electrical ring, magnet field and pressure on ion temperature and the efficiency of ion heating are studied. The results indicate that the whole heating of the plasma is accomplished through the magnetoelectric heating of the ions in the sheath of the electric ring and the radial transport of the heated ions. The ion temperature in the axial area increases with the bias voltage of electric ring, and their relationship is nonlinear. The ion temperature increases more than 20 eV when the bias voltage is 1000 V. A heating efficiency is achieved to be as high as 2%2.5% and increases with the bias voltage increasing. The magnetic field strength plays an important role in the limitation and heating of the ions. The efficiency of the magnetoelectric heating increases with the increase of the magnetic field strength when the magnetic field strength changes from 6.310-2T to 8.710-2T. The efficiency of the magnetoelectric heating increases with the pressure decreasing when the pressure chenges in a range of 0.020.8Pa.
Multiscale analysis of defect initiation on the atomistic crack tip in body-centered-cubic metal Ta
Authors: Lu Huai-Bao  , Li Jun-Wan  , Ni Yu-Shan  , Mei Ji-Fa  , Wang Hong-Sheng  ,   Department of Mechanics and Engineering Science, Fudan University, Shanghai 200433, China
Published: December 2020

The quasi-continuum method (QC), a multiscale method, is used to analyze body-centered-cubic (bcc) metal tantalum (tantalum, Ta) type Ⅱ crack-tip dislocation nucleation. Based on the relationship curves between dislocations emission position and stress intensity factor, the processes of dislocation defect initiation and development are investigated. Dislocation travels forward with different characteristics in different stages and the new nucleated dislocations expedite the already nucleated dislocation to move away from the crack tip. The analysis of initiation of the crack tip defects shows that they are the local defects that first appear, and with loading, more local defects emerge, which eventually move to the boundary, and lead to the type Ⅱ fracture. Furthermore, dislocation dissociation as well as extended dislocation is discussed. The partial dislocation nucleating before the perfect dislocation nucleation and emission is full proof that the dissociation of perfect dislocation takes place step by step, which means that the two minimum points on the energy curve have different formation mechanisms.
Influence of defect states on band gaps of the 4340 steel in epoxy in two-dimensional phononic crystal
Authors: Yue Lei-Lei  , Chen Yu  , Fan Guang-Hui  , He Jiao  , Zhao De-Xun  , Liu Ying-Kai  ,   Institute of Physics and Electronic Information, Yunnan Normal University, Kunming 650031,China
Published: December 2020

The band gaps of a two-dimensional phononic crystal are studied by using the plane-wave expansion method and the supercell calculations. The two-dimensional phononic crystal is formed by square-shape arrangement of 4340 steel inserted into epoxy resin. The band gaps of different structures are calculated such as defect-free, 45 crystal defect states, 90 crystal defect states, 135 crystal defect states and 180 crystal defect states. It is found that the bandwidth of defect state is about 31 times larger than that of the defect-free crystal; with F=0.10.9 the band gaps occur in different defect structures and increase with defect state angle increasing. In addition, the influences of filling fraction on the band gap number and the relative width of the minimum band gap are also discussed.
Manipulations of properties of the W-line emitting from the Si+ Self-ion-implanted Si thin films on insulated oxide layer
Authors: Wang Chong  , Yang Yu  , Yang Rui-Dong  , Li Liang  , Wei Dong  , Jin Ying-Xia  , Bao Ji-Ming  ,   Institute of Optoelectronic Information Materials, Yunnan University, Kunming 650091;,   Department of Electrical and Computer Engineering, University of Houston, Houston, Texas 77204, USA
Published: December 2020

The Si+ self-ion-implanted and annealing experiments are conducted on the Si film based on the silicon-on-insulator wafers. The photoluminescence (PL) spectroscopy is used to investigate the luminescence properties of these Si film samples. Plentiful optical structures are observed in the PL spectra, including the D1, D2, D3, X, and the sharp W lines. By comparing the normalized PL intensities recorded by the same spectral experiments, we obtain the optimum self-ion-implanted and thermal annealing parameters. In addition, the defect origins and optical properties of the series of the D peaks and W line are well discussed.
Floating zone growth and emission properties of single crystal LaB6cathode
Authors: Bao Li-Hong  , Zhang Jiu-Xing  , Zhou Shen-Lin  , Zhang Ning  ,   The Key Laboratory of Advanced Functional Materials, Ministry of Education, College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124, China
Published: December 2020

The high quality, high purity and large size Lanthanum hexaborides (LaB6) single crystals have been successfully grown by optical floating zone method. The optimum crystal growth parameters are listed as follow: sample rotation rate is 30 r/min and the growth rate is 810 mm/h. The largest thermionic emission current density of (100) crystal surface is 44.36 A/cm2 at 1873 K. The work function at absolute zero is calculated to be 1.99 eV by Richardson line method, and the average value of effective work functions at different temperatures are calculated to be 2.59 eV. The field emission characteristic of single crystal LaB6 field emitting single tip show that the maximum field emission current density is 4.9106 Acm-2 and the field enhancement factor is calculated to be 41500 cm-1, indicating excellent field emission performance. Thus, the single crystal is a promising cathode material for practical applications regarding to its excellent thermionic emission or field emission properties.
Molecular dynamics simulation of helium behavior in tungsten matrix
Authors: Wang Jun  , Zhang Bao-Ling  , Zhou Yu-Lu  , Hou Qing  ,   Key Laboratory for Radiation Physics and Technology, Institute of Nuclear Science and Technology, Sichuan University, Chengdu 610064, China
Published: December 2020

The helium behavior in tungsten matrix is investigated by means of molecular dynamics. Firstly, the He-W potential is created by combining the ZBL potential with the data from an ab intio method. The formation energy calculations predict that the most stable configuration for helium in interstitial position is the tetrahedral site, which is in good agreement with recent research results. The helium diffusion is simulated in great detail in a temperature range from 400 K to 1200 K, and the migration energy is obtained to be between the experimental data and the ab intio calculation result. Finally, the mechanism of helium accumulation in its initial stage is investigated from the viewpoint of energy. It is found that as the helium cluster grows, the binding energy of each additional helium atom to the cluster tends to increase, which is conducible to the further growth of the helium cluster.
First-principles study on the electronic structures, magnetism, and half-metallicity of full-Heusler X2YGa (X=Co, Fe, Ni; Y=V,Cr, Mn) alloys
Authors: Liu Xin-Hao  , Lin Jing-Bo  , Liu Yan-Hui  , Jin Ying-Jiu  ,   Department of physics, College of Science, Yanbian University, Yanji 133002, China
Published: December 2020

Using the full-potential linearized augmented plane wave method within the generalized gradient approximation, we investigatete the electronic structures, magnetisms and half-metallicities of the full-Heusler X2YGa (X=Co, Fe, Ni; Y=V, Cr, Mn) alloys. It is found that the spin-orbit coupling has little effect on the electronic structures, magnetisms and half-metallicities of the full-Heusler X2YGa (X=Co, Fe, Ni; Y=V, Cr, Mn) alloys. Without spin-orbit coupling the Co2VGa,Co2CrGa,and Fe2CrGa alloys are half-metallic or nearly half-metallic ferromagnets. With including the spin-orbit coupling, the spin-polarizations are lowered by about 1%, thus they still remain high spin-polarizations. The Fe2MnGa, Co2MnGa, Ni2CrGa, and Ni2MnGa alloys are conventional ferromagnets, whereas the Fe2VGa and Ni2VGa alloys are paramagnets.
Phase transformation and dielectric properties of lead zirconate stannate titanate ferroelectric ceramic under hydraulic compression
Authors: Jiang Dong-Dong  , Gu Yan  , Feng Yu-Jun  , Du Jin-Mei  ,   Laboratory for Shock Wave and Detonation Physics Research,Institute of Fluid Physics,China Academic of Engineering Physics,Mianyang 621900,China;,   Electronic Materials Research Laboratory, Xi'an Jiaotong University,Xi'an 710049, China
Published: December 2020

Nb-doped lead zirconate stannate titanate ferroelectric ceramic with composition Pb0.99Nb0.02[(Zr0.90Sn0.10)0.96Ti0.04]0.98O3 (PZST 90/10-4-2Nb) is studied in a hydraulic pressure range of 0300 MPa by released charge and dielectric measurements. Pressure-induced low temperature phase transition from ferroelectric rhombohedral (FR(LT)) structure to antiferroelectric orthorhombic (AO) strueture is investigated. Unpoled, poled and pressure-depolarized PZST 90/10-4-2Nb ferroelectric ceramics are used. The released charge quantity is 29.3 C/cm2 and the threshold pressure is 140 MPa during the phase transformation from FR(LT) structure to AO strueture. Dielectric properties show that the threshold pressure of the phase transformation from FR(LT) structure to AO structure is 136 MPa for poled ceramic and 104 MPa for unpoled ceramic. Obvious characteristic of phase transformation is not observed in pressure-depolarized ceramic.
A polarization-insensitive and double-face-absorption chiral metamaterial absorber
Authors: Gu Chao  , Qu Shao-Bo  , Pei Zhi-Bin  , Xu Zhuo  , Ma Hua  , Lin Bao-Qin  , Bai Peng  , Peng Wei-Dong  ,   Science College, Air Force Engineering University, Xi'an 710051, China;,   Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education, Xi'an Jiaotong University, Xi'an 710049, China;,   Synthetic Electronic Information System Research Department, Air Force Engineering University, Xi'an 710051, China
Published: December 2020

A polarization-insensitive and double-face-absorbing metamaterial absorber is presented, which is based on chiral structure. The unit cell of this absorber is comprised of a chiral structure and a dielectric substrate. Simulated absorbances under frontal and reverse incident directions indicate that the structure of this absorber is reciprocal, and thus this absorber has double-face-absorption property. Simulated absorbances under different polarization angles indicate that this absorber is polarization-insensitive. Simulated absorbances under different angles of incidence indicate that this absorber is narrow-angled. Simulated surface currents and magnetic energy density of the unit cell indicate that there exists cross coupling between electric field and magnetic field, and that the absorption is related to chirality. Simulated absorbances under different loss conditions indicate that dielectric loss of the substrate is dominant in the absorbing process, and that metal loss can be neglected. This absorber may have potential applications in some double-face-absorbing fields.
Host sensitized infrared quantum cutting of Er0.1Gd0.9VO4 crystal
Authors: Chen Xiao-Bo  , Xu Yi-Zhuang  , Zhang Chun-Lin  , Zhang Hui-Min  , Zhang Yun-Zhi  , Zhou Gu  , Li Song  ,   Applied Optics Beijing Area Major Laboratory, Beijing Normal University, Beijing 100875, China;,   The Chemistry and the Molecular Engineer College, Peking University, Beijing 100871, China;,   Institute of Physics, Chinese Academy of Sciences, Beijing 100080, China
Published: December 2020

The infrared quantum cutting phenomena of Er0.1Gd0.9VO4 crystal are studied in the present article. An interesting host sensitized infrared quantum cutting phenomenon is found, that is, there is a strong and broad excitation peak at 337.0 nm wavelength for its excitation spectrum of 1537.5 nm 4I13/24I15/2 infrared fluorescence. It can be recognized that the 337.0 nm excitation peak corresponds to the absorption of host GdVO4 crystal. Meanwhile, it is found that the integral fluorescence intensity of 1537.5 nm 4I13/24I15/2 infrared fluorescence, when the host absorption band is excited by 337.0 nm light, is about ten times larger than that of the sum of all other fluorescence intensities. Its infrared quantum cutting efficiency is similar to that of the excited 2H11/2 energy level and larger than that of others.
Positron annihilation study of the microstructure of Co doped ZnO nanocrystals
Authors: Qi Ning  , Wang Yuan-Wei  , Wang Dong  , Wang Dan-Dan  , Chen Zhi-Quan  ,   Hubei Nuclear Solid Physics Key Laboratory, School of Physics, Wuhan University, Wuhan 430072, China
Published: December 2020

ZnO nanopowders are mechanically mixed with a certain quantity of Co3O4 nanopowders to obtain 10at.% Co doped Co3O4/ZnO composites. The nanocomposites are annealed in argon atmosphere at different temperatures between 100 ℃ and 1200 ℃. The structure and the grain size of the nanocomposite are investigated by X-ray diffraction 2 scans. With annealing temperature increasing up to 700 ℃, Co3O4 phase gradually disappears, and ZnO grain size begins to increase significantly. After annealing at above 1000 ℃, Co3O4 phase completely disappears, and CoO phase (rock-salt crystal structure) appears. Positron annihilation lifetime measurements reveal a large number of Zn vacancies and vacancy clusters existing in the interface region of the Co3O4 /ZnO nanocomposites. These defects are gradually recovered after annealing at above 700 ℃, and their number is under the detection limit after annealing at 900 ℃. The same conclusion can be drawn from the coincidence Doppler broadening (CDB) measurements.
Ni-FUSI metal gate work function modulation technology
Authors: Zhou Hua-Jie  , Xu Qiu-Xia  ,   Key Laboratory of Microelectronics Devices & Integrated Technology,Institute of Microelectronics,Chinese Academy of Sciences, Beijing 100029,China
Published: December 2020

Through fabricating Ni-FUSI metal gate capacitors and analyzing their C-V and Vfb-EOT characteristics, it is found that Ga or Yb has more favorable modulation ability than conventional dopants. The work function of Ni-FUSI metal gate is modulated close to the top of valince band and the bottom of conduction band, which meets the requirement of high performance CMOS devices. The high modulation abilities of Ga and Yb are explained by dipole theory. Moreover, it is found that the capacitance value of Ni-FUSI metal gate capacitor increases after incorporating Ga or Yb into Ni-FUSI metal gate, but the gate leakage current decreases. And the detailed explanation for the above phenomena is also included in this article by analyzing C-V and gate leakage current characteristics.
A physics-based model of insulated gate bipolar transistor with all free-carrier injection conditions in base region
Authors: Du Ming-Xing  , Wei Ke-Xin  ,   School of Electrical Engineering and Automation, Tianjin University, Tianjin 300072,China;Tianjin Key Laboratory of Control Theory & Applications in Complicated System, Tianjin University of Technology, Tianjin 300384, China
Published: December 2020

A physics-based model of insulated gate bipolar transistor (IGBT) with all free-carrier injection conditions in a base region is presented, from which the ambipolar transport equations (ATEs) in high-level injection and low-level injection are deduced separately. Moreover, the boundary conditions of ATE are determined. In a more compact solution a Fourier-series solution for the ATE is used in this paper. Simulation and experimental results given by manufacturers are presented and compared with each other to validate the modeling approach. Physics-based IGBT model is used which is proved accurate.
Multi-component induction logging response in large dielectric formation
Authors: Hong De-Cheng  , Yang Shan-De  ,   The Center for Theoretical Physic, Jilin University, Changchun 130021, China
Published: December 2020

Wireline induction logs operating at a frequency of some tens of kHz are used to detect the resistivity of hydrocarbon reservoir. The dielectric constant of typical formation is usually smaller than that of pure water and its effect is negligible for induction log. However some peculiar rocks including organic matter named source rock have large dielectric permittivities caused by polarization, which can lead the traditional induction logging to have an nusual log response. Multi-component induction logging is new log method and has been developed in nearly ten years, which can provide more information about formation than traditional axial instrument and has large potential applications. In this paper, we study the effect of large dielectric constant on multi-component induction logging response and extract the information about resistivity and dielectric permittivity through the different combinations, there by realizing the formation parameters reconstruction and intuitive recognition for the hydrocarbon source rock.
Season division and its temporal and spatial variation features of General atmospheric circulation in East Asia
Authors: Hou Wei  , Sun Shu-Peng  , Zhang Shi-Xuan  , Zhao Jun-Hu  , Feng Guo-Lin  ,   Climate Center, Beijing 100081, China;,   College of Atmospheric Sciences, Lanzhou University, Lanzhou 730000, China
Published: December 2020

Using the NCEP-DOE Reanalysis 2 data of air temperature, geopotential height, relative humidity and wind field of 17 pressure levels from 1979 to 2009, and the Multi-factor Fisher optimal dissection method, the seasons of the general atmospheric circulation in East Asia are diuided. The main results are as follows. (1)The seasonal establishment of atmospheric general circulation is initiated from subtropic of the stratosphere in East Asia. In the troposphere the spring and the summer first start from the tropical regions, and then extend into middle latitudes. The autumn and the winter first start from middle latitudes, and then extend into low latitudes. (2) In the troposphere the seasonal establishment of atmospheric general circulation is more consistent, and it is very different from that in the stratosphere. And the seasonal establishments of the middle and the low level of the stratosphere are not very consistent. (3)In the past 30 years, the four seasons have started much earlier in about 6 years, in which years some stronger El Nio phenomena just happened. That implies that the El Nio phenomenon causes abnormal seasonal variation.
Extremely low temperature and its composite index based on stochastically re-sorting detrended fluctuation analysis
Authors: Hou Wei  , Zhang Da-Quan  , Qian Zhong-Hua  , Feng Guo-Lin  ,   National Climate Center, Beijing 100081, China;,   Key Laboratory of Regional Climate Environment Research for Temperature East Asia, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China;,   College of Atmospheric and Sciences, Lanzhou University, Lanzhou 730000, China;,   College of Physical Science and Technology, Yangzhou University, Yangzhou 225002, China
Published: December 2020

By combining the detrended fluctuation analysis (DFA) method with surrogate data method, and using the heuristic segmentation algorithm as well as Chi-Square statistics, we develop a new method to determine the threshold of extreme events, e.g. stochastically re-sorting detrended fluctuation analysis(S-DFA) method. By using the S-DFA method, we obtain the thresholds of extremely low temperature events from 1961 to 2006 in China and analyze their spatiao temporal characteristics of distribution. We also validate the effectiveness of the S-DFA method through extreme event detection using the temperature series. By defining the composite index of extremely low temperature events from the angle of predictability, this composite index is integrated with the information about the frequency and the strength of the extremely low temperature events, with considering the characteristic of regional climate system. Based on the composite index, we divide the extremely low temperature events during 19612006 in China into four different zones according to their own rank. The composite index of extremely low temperature tends to be katabatic on the whole, Before the the early 80's in the 20th century, the composite index changed according to two distinct 10-year quasi-periods, and after that the composite index was in a downward trend and was well below the average. Until after the mid-90's in the 20th century, it rose to about average value once again.
Coupled KdV equation: similarity reduction and analytical solution
Authors: Cheng Xue-Ping  , Li Jin-Yu  , Xue Jiang-Rong  ,   Physics,Mathematics and Information College of Zhejiang Ocean University, Zhoushan 316004, China;,   Department of Physics, Shanghai Jiaotong University,Shanghai 200240, China
Published: December 2020

Using the CK direct method, we obtain the similarity reduction of coupled KdV equation, which is then explained in detail by group theory. To check the Painlev integrability of coupled KdV equation, the reduction equation is also classified by means of the Painlev test, and three types of P-integrable models are found. Finally, it is shown that the coupled KdV equation has kinds of traveling wave solutions, including conoidal periodic wave solution, soliton solution, and so on.
Detection of weak signal based on the sea clutter scattering
Authors: He Jing-Bo  , Liu Zhong  , Hu Sheng-Liang  ,   Electronics Engingeering College, Naval University of Engineering, Wuhan 430033, China
Published: December 2020

Sea clutter scattering is analyzed in the paper. The stochastic differential equations are given for the physical quality of sea clutter. The diffusion process model is built by using Ito formula. These processes are represented as Ito stochastic differential equations, which enables the identificating their stochastic volatilities with certain free functions that serve as calibrating the model. Finally the correlation detection method is used to detect weak signal from sea clutter.
Decoy-state quantum key distribution with practical light source
Authors: Jiao Rong-Zhen  , Zhang Chao  , Ma Hai-Qiang  ,   Science School, Beijing University of Post and Telecommunication, Beijing 100876,China
Published: December 2020

The performance of active decoy-state quantum key distribution (QKD) system with a practical light source is compared with that of passive decoy-state QKD. The effect of statistical fluctuation due to a finite data size on final secret key rate is analyzed. This procedure is based on the standard error analysis on the assumption that all the variables measured in the experiment fluctuate around their asymptotic values. The relation between key generation rate and secure transmission distance is shown with exchanged quantum efficiency of threshold detector (d=1 and d=0.4) under the condition of active decoy-state (or passive decoy-state ) QKD which we pick the data size to be N=6.0109. This analysis will provide important parameters for practical QKD experiment.
Effects of external field parameters on conversion from ultracold atoms to heteronuclear triatomic molecules
Authors: Li Guan-Qiang  , Peng Ping  ,   Faculty of Science, Shaanxi University of Science and technology, Xi’an 710021, China
Published: December 2020

We investigate the effects of external field parameters, including the strength of Rabi pulse, its width, and single-photon detuning, on conversion from ultracold atoms to heteronuclear triatomic molecules by two-photon stimulated Raman adiabatic passage. It is found that the conversion efficiency of the system decreases first with the strength of the Stokes pulse increasing, then oscillates, and finally approaches a stable value, which is less than 1. But for the pump pulse, the efficiency first increases with the increase of the pulse intensity, and then approaches 1 quickly. The results show that the two pulses play different roles in the conversion. The pulse width can not only determine the final conversion efficiency, but also be used to reflect the time needed for stable conversion. The system has a higher efficiency of conversion for red detuning pump laser, but the blue detuning is not conducive to the formation of the molecules. In addition, the differences of the adiabaticity and conversion efficiency among different reaction pathways are discussed.
Stochastic resonance of square wave signal in an overdamped harmonic oscillator
Authors: Lu Zhi-Xin  , Cao Li  ,   Department of Automobile Engineering, Hubei University of Automotive Technology, Shiyan 442002, China;,   School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
Published: December 2020

The output power and the signal-to-noise ratio of an overdamped harmonic oscillator are calculated in the case of square wave signal input. The corresponding stochastic resonance phenomenon and the comparison with the case of cosine signal input are discussed. Results reveal that there appear the stochastic resonances in these two cases, and the phenomenon in which the resonance and suppression are coexistent, but the coexistence phenomenon appears in the different stochastic resonance curves for these two models.
Research on impulsive synchronization approach ofparameter uncertain hyperchaotic systems with time-delay
Authors: Luo Yong-Jian  , Yu Qian  , Zhang Wei-Dong  ,   Institute of Military Electronic Engineering, Xi’an Communications Institute, Xi’an 710106, China;,   Administrant Brigade of Postgraduate, Xi’an Communications Institute, Xi’an 710106, China;,   Institute of Command Information Systems, Xi’an Communications Institute, Xi’an 710106, China
Published: December 2020

In this paper, based on the Lyapunov stability theory, the impulsive synchronization asymptotic stability condition for different hyperchaotic systems with time delay and parameter uncertainty is first presented by using the linear feedback of state variable error between the slave system and the master system as the impulsive control signal. After the synchronization, a digital communication system with time delay is provided to achieve secure communication. This scheme is of high security and robustness. Moreover, computer simulations show that in the communication system, the synchronization of the systems could be achieved quickly, and by using chaotic cipher sequence to encrypt the digital signal, the useful information signal can be recovered effectively from the receiver.
A fast algorithm with convergence for generalized predictive function control of Hnon chaotic system
Authors: Liu Wen-Long  , Pang Shuang-Jie  , Zhang Ji-Feng  ,   Northeast Petroleum University at Qinhuangdao, Qinhuangdao 066004, China;,   Qinhuangdao Institute of Technology, Qinhuangdao 066100, China
Published: December 2020

A kind of fast generalized predictive function control algorithm with convergence of tracking for Hnon chaotic system is proposed. First, based on the existing generalized predictive function control algorithm, the matrix inversion computation in the control law is avoided because special basis functions are selected according to the motion characteristics of chaotic system and the change trend of practical control input. Then, by introducing the determinate feedforward gain matrix into performance index function, it is convergent that the output of Hnon chaotic system follows reference signal. The simulated results show the effectiveness of this algorithm.
17.5 Gbit/s random bit generation using chaotic output signal of mutually coupled semiconductor lasers
Authors: Tang Xi  , Wu Jia-Gui  , Xia Guang-Qiong  , Wu Zheng-Mao  ,   School of Physics, Southwest University, Chongqing 400715, China
Published: December 2020

Based on two mutually coupled semiconductor lasers linked by fiber, a chaotic seed signal with a 10 GHz ultra-broadband is obtained experimentally. Adopting an 8-bit analog-to-digital converter, the seed signal is converted into a binary bit stream. By an exclusive-OR operation and the most significant bit rejection, a random bit sequence at a rate up to 17.5 Gbit/s, which has passed both the National Institute of Standard and Technology statistical test and the Diehard test, is obtained.
A new pseudo-random number generator and application to digital secure communication scheme based on compound symbolic chaos
Authors: Wang Fu-Lai  ,   Institute of Applied Mathematics, Zhejiang University of Finance and Economics, Hangzhou 310018, China
Published: December 2020

A new concept of compound symbolic chaotic series is proposed. According to the kneading pair series in symbolic dynamics, by compounding a pseudo-random series with sub-series on condition of kneading rules we obtain a new symbolic chaotic series which is then transformed into a pseudo-random binary number (PRN) series. The length of the new PRN series elongates at a speed of geometric procession with iteration number. Theoretical and experimental analyses both prove that the above algorithm provides an effective PRN generator. To apply the algorithm to digital secure communication, a new cellular automata is established. With the automata, the data expansion is avoided, the encryption is finished quickly, the obvious avalanche effect can be produced, and thus the security is improved.
Investigation of sign spectrum sensing method
Authors: Sun Biao  , Jiang Jian-Jun  ,   Department of Electronic Science & Technology, Huazhong University of Science & Technology, Wuhan 430074, China
Published: December 2020

Spectrum measurement technology is widely used in wireless communication, electronic countermeasure, cognitive radio, smart absorbing structure, etc. In this paper we propose a new sign spectrum sensing approach which contains mainly data acquiring stage and spectrum sensing stage. In the former stage, based on the standard compression sensing, we propose a new sign data acquiring approach, in which we preserve only the sign information about the measurements, so that the data storage space is reduced. In the latter stage, we construct the spectrum sensing algorithm based on the consistent reconstruction principle and the gradient steepest descent algorithm. Simulation results demonstrate that this approach reduces the number of measurements and the data storage space, and at the same time this approach perfectly acquires the spectrum information. This approach can well be used in front spectrum measurement stage of wireless commucation, electronic countermeasure, smart absorbing structure and cognitive radio.
First-principles calculation on electronic structure and optical properties of iron-doped SnO2
Authors: Lu Yao  , Wang Pei-Ji  , Zhang Chang-Wen  , Feng Xian-Yang  , Jiang Lei  , Zhang Guo-Lian  ,   School of Physics, University of Jinan, Jinan 250022, China
Published: December 2020

By the full-potential linearized augmented plane wave method (FP-LAPW), we investigate the electronic structures and optical properties of Fe-doped SnO2 system, including the density of states (DOS), band structure, dielectric function and other optical spectra. The calculation indicates that the Fe doped materials are all direct transition semiconductors with half-metallic property. With the increase of Fe-doping concentration, the Fermi level goes into valence band gradually, and the band gap reduces with the coupling of Fe atoms increasing. Moreover, impurity can change the property of the bond formation to some extent, and make it have metallic bond characteristic. Furthermore, we find that the optical spectrum (such as absorption spectrum), extinction coefficient, etc are blue shifted, corresponding to the imaginary part of dielectric function. The peaks are related to the transition of electrons, which indicates internal relationship between the electronic structures and optical properties theoretically.