bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of annealing time on the microstructural and electrochemical properties of B-doped nanocrystalline diamond films
Authors: Hu Heng  , Hu Xiao-Jun  , Bai Bo-Wen  , Chen Xiao-Hu  ,   College of Chemical Engineering and Material Science, Zhejiang University of Technology, Hangzhou 310014, China
Published: December 2020

The effects of annealing time under 1000 ℃ on the microstructural and the electrochemical properties of boron-doped nanocrystalline diamond (BDND) films are investigated by HRTEM, UV and visible Raman spectroscopy, and cyclic voltammetry measurements. The results show that the size of nano-diamond grain in the film decreases with annealing time increasing. When the annealing time is 0.5 h, the grain size decreases from about 15 nm in the unannealed sample to about 8 nm and the content of diamond phase increases. When the annealing time increases to 2.0 h, the diamond grain size decreases to 2-3 nm, and the content of diamond phase decreases with the grain boundary increasing. In the case of annealing time of 2.5 h, the grain size of nano-diamond and the content of diamond phase increase slightly. The variations of nano-diamond grain size and the content of diamond phase indicate that the transformation between the diamond phase and the amorphous carbon occurs under the annealing with different times. The visible Raman spectra show that the G-peak position and the ID/IG value exhibit similar variations with annealing time increasing, revealing that the ordering of the amorphous graphite phase is improved when sp2 carbon cluster increases in number or size. The reactions on the electrode surface are quasi-reversible when the annealing times are 0.5, 1.0, 1.5 and 2.0 h. On the contrary, the reactions are irreversible when the sample is unannealed or annealed for 2.5 h. It is observed that the annealing treatment is beneficial to the improvement of the electrode mass transfer efficiency of BDND film. When the annealing time is 0.5 h, the electrode mass transfer efficiency as well as the ability of catalytic oxidation of BDND film is best. The results suggest that the smaller size of nano-diamond grain, the higher content of diamond phase and the uniform distribution of the nanocrystalline diamond grains are conducible to the improvement of the reaction reversibility on the electrode surface and the ability of catalytic oxidation of BDND films.
The study on adaptability and effect of mesh-inducing for plasma immersion ion implantation on non-conductor polymer
Authors: Huang Yong-Xian  , Leng Jin-Song  , Tian Xiu-Bo  , Lü Shi-Xiong  , Li Yao  ,   State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001, China;,   Center for Composite Materials and Structures, Harbin Institute of Technology, Harbin 150001, China
Published: December 2020

Plasma immersion ion implantation (PIII) of non-conductor polymer materials is inherently difficult because the voltage across the sheath is reduced by the voltage drop across the insulator due to dielectric capacitance and charge accumulation on the insulator surface. Based on the particle-in-cell (PIC) model, the secondary electron emission (SEE) coefficient is related to the instant energy of implanting ions. Statistical results can be obtained through scouting each ion in the plasma sheath. The evolution of surface potential is simulated for ion implantation on insulator materials. The effects of thickness, dielectric constant and SEE coefficient on the surface bias potential and the effect of mesh-inducing are studied. For thicker non-conductor polymer, it is difficult to achieve omni-directional implantation by self-bias. The mesh-assisted PIII can improve the equivalent surface potential, suppress the emission of secondary electrons and provide an effective way for ion implantation on insulator.
Investigations on the thermal stability of fatigue dislocation structures in a single-slip-oriented copper single crystal
Authors: Guo Wei-Wei  , Ren Huan  , Qi Cheng-Jun  , Wang Xiao-Meng  , Li Xiao-Wu  ,   Institute of Materials Physics and Chemistry, College of Sciences, Northeastern University, Shenyang 110004, China;,   Key Laboratory for Anisotropic and Texture of Materials, Ministry of Education, Northeastern University, Shenyang 110004, China
Published: December 2020

The fatigue dislocation structures in cyclically saturated [4 18 41] single-slip-oriented Cu single crystal at different values of plastic strain amplitude pl, as well as their thermal stabilities under annealing at different temperatures for 30 min are studied using the electron channeling contrast (ECC) technique in scanning electron microscopy (SEM). It is found that the dislocation structures, such as veins, PSB ladders, PSB cells, Labyrinths, etc. undergo an obvious process of recovery after annealing at 300 ℃. However, when the annealing temperature is higher than 500℃, those dislocation structures basically disappear, and the recrystallization takes place in all specimens, meanwhile, annealing twins form in most cases. The occurrence of the recrystallization and the formation of annealing twins are related not only to the annealing temperature and applied pl, but also closely to the accumulative cyclic plastic strain.
The effects of shape and position on field distribution of discontinuous crack
Authors: Zhang Chun-Lai  , Liu Chun-Ming  , Xiang Xia  , Wang Zhi-Guo  , Li Li  , Yuan Xiao-Dong  , He Shao-Bo  , Zu Xiao-Tao  ,   School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054, China;,   Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

Elliptic paraboloid model is established, and three-dimensional finite-difference time-domain method has been employed to simulate the field distribution of discontinuous crack with different shapes and positions in fused silica output subsurface under 355 nm laser incidence. Results show that both electric field intensity and the number of enhanced points (with |E| 2.0 V/m) follow a trend of first increasing and then decreasing with the increase of collinear axis length of ellipsoid. The light intensity enhancement factor reaches a maximal value when the axial ratio is 1.1 to 1.2. If parallel collinear axis length of ellipsoid increases, the electric field intensity first increases gradually, and then becomes stable when the axial ratio is 0.53. At the same time, the number of enhanced points grows rapidly.
Recording and numerical reconstruction of single digital tomographic hologram
Authors: Zhou Wen-Jing  , Hu Wen-Tao  , Qu Hui  , Zhu Liang  , Yu Ying-Jie  ,   Department of Precision Mechanical Engineering, Shanghai University, Shanghai 200072, China
Published: December 2020

In this paper, we study the single tomographic hologram (STH). We first define the STH and analyze the frequency spectrum of the STH containing three projections, then perform the simulation analysis including the digital recording, information separation and numerical reconstruction of the STH, and finally we rebuild an experimental setup to record the single tomographic hologram from three projections. A phase grating with 100 m period is used as a test sample. The reconstructed period error of grating is between 4%-5%. Both simulation analyse and experimental results demonstrate the feasibility and validity of the STH. In the next work, the improvement of the reconstruction quality for single digital tomographic hologram will be discussed.
Investigation of the cathode electric field at the initial stage of explosive electron emission
Authors: Zuo Ying-Hong  , Wang Jian-Guo  , Zhu Jin-Hui  , Niu Sheng-Li  , Fan Ru-Yu  ,   Department of Engineering Physics, Tsinghua University, Beijing 100084, China;,   Northwest Institute of Nuclear Technology, Xi'an 710024, China
Published: December 2020

To investigate a complex physical phenomenon and its evolution law at the cathode surface at the initial stage of the explosive electron emission process in a high-power diode, in this paper we present a model of a planar vacuum diode with a field emission cathode. The model is one-dimensional and nonstationary. To study the space charge effect of the emitted electrons on the electric field at the cathode surface, Poisson's equation is solved numerically by using our developed code, and the time-dependences of the electric field at the cathode surface for different cases are obtained. The results show that the electric field at the cathode surface first oscillates and finally yields a steady state. The absolute value of the steady electric field at the cathode surface is higher for the higher field enhancement factor at a given applied electric field, and the applied electric field has the same effects on the steady value at a certain field enhancement factor. The electric field at the cathode surface completely determines the extracted field emission current density from the cathode, and at the same time, the electric field at the cathode surface is influenced by the emitting current density.
Simulation of optical potential of Gaussian laser standing wave by diffraction of straight edge
Authors: Zhang Bao-Wu  , Zhi Li-Xiang  , Zhang Wen-Tao  ,   College of Metrology and Measurement Engineering, China Jiliang University, Hangzhou 310018, China;,   College of Electronic Engineering, Guilin University of Electronic Technology, Guilin 541004, China
Published: December 2020

In order to study the effect of substrate on the focusing laser beam in atom lithograph, the simulations of optical potential of Gaussian laser standing wave in the presence and the absence of straight edge diffraction are performed based on the scalar optical theory. The similarities and differences in optical potential between the diffractive Gaussian and non-diffractive Gaussian laser beam are fully indicated by the three-dimensional and cross-sectional figure. The effects of the distance between laser axis and substrate, the distance between laser waist and reflective mirror are fully studied.
Theoretical studies on nonvolatile holographic recording for LiNbO3:Cu:Ce crystals
Authors: Shen Yan  , Zhang Guo-Qing  , Yu Wen-Bin  , Guo Zhi-Zhong  , Zhao Ye-Quan  ,   School of Electrical Engineering and Automation, Harbin Institute of Technology, Harbin 150080, China
Published: December 2020

The steady-state nonvolatile two-step, two-color holographic recording performance is studied theoretically for LiNbO3:Cu:Ce based on the two-center model, with taking into account the direct electron transfer between the deep-trap center Cu+/Cu2+ and the shallow-trap center Ce3+/Ce4+ due to the tunneling effect. The results show that the total space-charge field is determined by the space-charge field on the deep-trap center, and the direct electron exchange between the Cu+/Cu2+ and the Ce3+/Ce4+ levels through the tunneling effect dominates the charge-transfer process in the two-step, two-color holographic recording. Therefore, the material parameters related to this direct tunneling process play a key role in the two-step, two-color holography performance.
Dissipative dynamics of few-photon superposition states in optical microcavity
Authors: Wen Hong-Yan  , Yang Yang  , Wei Lian-Fu  ,   Quantum Optoelectronics Laboratory, School of Physics and Technology, Southwest Jiaotong University, Chengdu 610031, China;,   State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat-Sen University, Guangzhou 510275, China
Published: December 2020

Detections and manipulations of quantum optical state at single-photon level have received much attention in the current experiments. Here, by numerically calculating the time-evolved Wigner functions, we investigate the dynamics of the typical non-classical state, i.e., few-photon superposition states in a dissipating optical microcavity. It is shown that the negativity of their Wigner function vanishes with dissipation. But this does not imply that all the non-classical features of the dissipative quantum state disappear. In fact, it is shown that the value of the second-order correlation function g(2)(0) (which serves usually as the standard criterion of a typical non-classical effect, i.e., the anti-bunching of photons, if g(2)(0)g(2A)(0) varies with the cavity dissipation and thus could be used to describe the physical effects of the dissipative cavity. Finally, we discuss the experimental feasibility of our proposal with a practically-existing cavity QED system.
Generation of negative pressure of underwater intensive acoustic pulse and cavitation bubble dynamics
Authors: Zhang Jun  , Zeng Xin-Wu  , Chen Dan  , Zhang Zhen-Fu  ,   College of Opto-electronics Science and Engineering,, National University of Defense Technology, Changsha 410073, China;,   College of Science, National University of Defense Technology, Changsha 410073, China
Published: December 2020

In this paper, the high speed photography and the pressure measurement are used to study the propagation and focusing process of the underwater intensive acoustic pulse which is reflected from an ellipsoidal reflector. The experimental results indicate that the reflector contribute to both the sound energy focusing and the generation of a negative pressure portion of the intensive acoustic pulse, and the cavitation bubble cluster will be induced to grow accordingly. Based on the experimental results, a sound propagation model derived from Kirchhoff diffraction integral and the equation of bubble dynamics proposed by Qian and Xiao [Qian Z W and Xiao L 2003 Chin. Phys. Lett. 20 80; Qian Z W and Xiao L 2008 Chinese Physics B 17 3785] are used to numerically study the propagation of the intensive acoustic pulse and the bubble motion. The numerical results indicate that the "wake wave" and "edge wave" will evolve into the negative pressure portion of the intensive acoustic pulse in front of the far focus of the reflector and the "center wave" will evolve into the negative pressure part beyond the far focus of the reflector. When the bubble is subjected to the reflected wave, it will be compressed and oscillate periodically during the positive pressure phase, and it will expand during the negative pressure phase of the incident pulse. And after the reflected wave passes, the typical processes of expanding, collapsing and rebounding can be seen clearly from the photographs. The research results have practical significance for understanding the propagation characteristic of the underwater intensive acoustic pulse with an ellipsoidal reflector.
A new method of obtaining perturbation vertical profiles in estimating the atmosphere gravity wave parameters
Authors: Cheng Hu-Hua  , Zhong Zhong  , Cen Jin  , Deng Shao-Ge  ,   Institute of Meteorology, PLA University of Science and Technology, Nanjing 211101, China;,   Meteorological and Oqanography Center of Nanjing Military Region Air Force, Nanjing 210018, China;,   Unit No. 68028 of PLA, Lanzhou 730058, China
Published: December 2020

The gravity wave is the fundamental dynamic process in the atmosphere, and one of the important theoretical studies of atmosphere dynamics is to estimate the gravity wave parameters. Due to the inherent deficiency of the curve fitting method for the vertical perturbation profile (VPP), a new method is proposed in obtaining the profile for estimating the reasonable gravity wave parameters. Based on the features of cone of influence in wavelet transformation and its maximum value, which is considered as the critical value for background profile and perturbation profile, the VPP is obtained with a 10th-order Butter Worth highpass filter for the signal with the magnitude less than the critical value. With the Morlet wavelet and Fourier power spectrum analyses for the numerically simulated zonal wind and meridional wind, it is found that there are neither distinct background signals nor false signal including in the VPPs, which overcomes the deficiency of curve fitting method. Therefore, the proposed method is excellent compared with the widely used curve fitting method in obtaining the VPPs, and the reasonable atmosphere gravity wave parameters could be estimated with the new method.
Mode transition of inductively coupled plasma in interlayer chamber
Authors: Du Yin-Chang  , Cao Jin-Xiang  , Wang Jian  , Zheng Zhe  , Liu Yu  , Meng Guang  , Ren Ai-Min  , Zhang Sheng-Jun  ,   Key Laboratory of Basic Plasma Physics Chinese Academy of Sciences, University of Science and Technology of China Department of Modern Physics, Hefei 230026, China;,   Test Physics and Numerical Mathematic Laboratory, Beijing 100076, China
Published: December 2020

We do some research on E-H mode transition of inductively coupled plasma (ICP) in the interlayer chamber, using the microwave phase and plasma spectrum diagnotic technique. The mode transition between E and H mode is a sudden changes phenomenon. The input power of the transition varies as the pressure changes in the chamber. The transition power from H to E is less than from E to H, so the hysteresis in power hence is established. The change of the relative spectral intensity is basically the same the variation of the electron density with input power. We obtain a stable plasma source, with an electron density ranging from 3.85× 1011 cm-3 to 4.68× 1011 cm-3, an outer surface area of 0.3 m2, and a thickness of 2 cm.
Plastic behavior of Zr51Ti5Ni10Cu25Al9 metallic glass under planar shock loading
Authors: Yu Yu-Ying  , Xi Feng  , Dai Cheng-Da  , Cai Ling-Cang  , Tan Hua  , Li Xue-Mei  , Hu Chang-Ming  ,   National key Laboratory of Shock Waves and Detonation Physics, Institute of Fluid Physics, Chinese Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

Planar shock compression experiments are performed on a Zr-based bulk metallic glass (BMG), Zr51Ti5Ni10Cu25Al9 at peak shock stresses from 10 GPa to 27 GPa to investigate its plastic behavior under high pressure and high strain-rate. The particle velocity profiles measured at the free surface of the samples are analyzed to estimate longitudinal stresses of the Zr-based BMG in the shock loading process,and then shear stresses are obtained by comparing longitudinal stresses with a hydrostat. Though there is an obvious relaxation effect after elastic front, the Hugoniot elastic limit of the Zr-based BMG is found to increase with shock stress increasing. However, the shear stresses across the plastic shock front display stress hardening above the Hugoniot elastic limit followed by a stress relaxation (softening) to Hugoniot state, and the relaxation level also increases with shock stress increasing. The changes of shear stresses under planar shock compression are consistent with the results from molecular dynamic simulations, but obviously different from the pressure-shear impact experimental results or uniaxial stress impact experimental results.
Singular perturbation solution of a class of sea-air oscillator for the El Niño/La Niña-southern oscillation
Authors: Han Xiang-Lin  , Du Zeng-Ji  , Mo Jia-Qi  ,   Faculty of Science, Huzhou Teacher College, Huzhou 313000, China;,   School of Mathematical Sciences, Jiangsu Normal University, Xuzhou 221116, China;,   Anhui Nornal University, Wuhu 241003, China
Published: December 2020

The EI Niño/La Niña and southern oscillation is an interannual phenomenon involved in the tropical Pacific ocean-atmosphere interactions. In this paper, the aim is to create a method of asymptotically solving the nonlinear singularly perturbed problem for the ocean-atmosphere oscillator models. And according to a class of ocean-atmosphere oscillator models, employing the singular perturbation method, we study the approximate solution of corresponding problem. The obtained results from singular perturbation method can be used for analyzing the sea surface temperature anomaly and the thermocline depth anomaly in the equatorial Pacific of the atmosphere-ocean oscillator for the EI Niño/La Niña and southern oscillation model.
Research of the early debris expansion from high-altitude nuclear explosions
Authors: Yang Bin  , Niu Sheng-Li  , Zhu Jin-Hui  , Huang Liu-Xing  ,   Northwest Institute of Nuclear Technology, Xi'an 710024, China
Published: December 2020

Based on magnetohydrodynamic theory a shell model is developed to describe debris motion of high-altitude nuclear explosion. The debris motion parameter of Starfish is simulated. The model is verified by comparison with the results available from the literature. For the comparison between typical high-yield and low-yield nuclear explosion, the debris motions of kiloton and megaton at 100 km, 400 km and 1500 km are especially simulated. The difference in expansion law, caused by explosion yield, is analyzed. The results show that explosion condition and atmospheric environment have a significant influence on the expansion of the law of the debris cloud, and the debris environmental parameters in different directions are significantly different from each other.
Back-gate bias effect on partially depleted SOI/MOS back-gate performances under radiation condition
Authors: Zhou Xin-Jie  , Li Lei-Lei  , Zhou Yi  , Luo Jing  , Yu Zong-Guang  ,   School of Electronic Science and Engineering, Southeast University, Nanjing 210096, China;,   No.58th Research Institute of China Electronics Technology Group Corporation, Wuxi 214035, China
Published: December 2020

According to the partially depleted SOI/MOS device's band gap, starting with the electric field, which is a factor of back-gate charge stack, we combine SOI device capacitance model and flat capacitance model for finding the way to keep electric field at the interface of Si/SiO2, and build a back-gate bias model. For validating the new model, we use alloy-agglomeration at the back gate. After radiation experiments, we compare the results of back-gate effect on NMOS with those on PMOS. It is concluded that as far as NMOS is concerned, negative voltage at back-gate can eliminate the back-gate effect which influence the performance of device, and improves the performance of front-gate. However negative voltage at back-gate makes the performance of PMOS worse. Therefore, when we use the back-gate bias to improve the performance of device, we must consider the performances of NMOS and PMOS and compromise the choice of the voltage which is applied to the back-gate. This research supplies not only a design scheme for hardening back-gate effect of SOI devices under radiation condition, but also a support in theory for integrated circuit design and manufacture, which is used in space.
Microstructure of spray-formed FGH4095 after static recrystallization
Authors: Zhang Yu  , Ge Chang-Chun  , Shen Wei-Ping  , Qiu Cheng-Jie  ,   Institute of Special Ceramics and Powder Metallurgy, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China
Published: December 2020

For the study of solution heat treatment characteristic of spray-formed FGH4095 after near iso thermal forging, the superalloy specimens, which have been hot isostatically pressed (HIPed) and forged with a 75% compression ratio, are solution heat treated at 1120℃, 1140℃ and 1160℃ for 10, 20 and 40 min respectively, and oil quenched. The characteristics of static recrystallization process including grain size and precipitated phase after heat treatment are discussed. The results show that the temperature of solution heattreatment has a great influence on the microstructure. In heat treatment at 1120℃ the recrystallization is slow, and the necklace structure is formed due to the localized incomplete recrystallization; at 1140℃ for 40 min, the static recrystallization is basically completed, the average grain size is about 8 μm; at 1160℃, the recrystallization is finished in 10 min, and the grains grow up to about 18 μm.
Soliton excitation with high-oder-nonlinearity of spinor Bose-Einstein condensate in an optical lattice
Authors: Xie Yuan-Dong  ,   School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou 510006, China
Published: December 2020

Soliton excitation with high-oder-nonlinearity of spinor Bose-Einstein condensate in an optical lattice is studied in detail. The exact solution for bright soliton which is expressed as an elliptic integral is found, and the analytic solution for dark soliton with particular parameters is presented. The energy is also found.
Spontaneously generated coherence induced transparency in an asymmetric semiconductor quantum well
Authors: Chen Ai-Xi  , Chen Yuan  , Deng Li  , Kuang Yun-Feng  ,   Department of Applied Physics, East China Jiaotong University, Nanchang 330013, China
Published: December 2020

Properties of transmission of a weak pulsed light in an asymmetric semiconductor quantum well are investigated. Under the condition of same physical parameters, we research absorption and chromatic dispersion of pulsed light via changing the cross coupling term resulting from the spontaneously generated coherence effect in an asymmetric semiconductor quantum well. It turns out that the absorption of quantum well medium is continually decreasing with the enhancement of spontaneously generated coherence effect. Simultaneously, strong chromatic dispersion turns into transparent window.
Optical properties of amorphous SiOx:C particles calcined in air at elevated temperature
Authors: Zheng Li-Ren  , Huang Bai-Biao  , Wei Ji-Yong  , Dai Ying  ,   College of Physics and Electronic Engineering, Taishan University, Tai'an 271021, China;,   State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, China
Published: December 2020

Amorphous SiOx:C particles are prepared by pyrolyzing method, and then they are calcined in an air ambient at different temperatures. The structures mophologies and optical properties of samples are analyzed with FTIR spectrum, scanning electron microscopy and fluorescent microscope, respectively. The results show that the luminescence band is blue-shifted with the increase of the annealing temperature. The particles exhibit the highest photoluminescence intensity with the 417 nm peak when annealed at 500 ℃. And the particles possess red, green or blue light emissions at room temperature when irradiated with appropriate wavelengths. Upon heating at a higher temperature (600 ℃ or 800 ℃), the fluorescence intensity of the SiOx:C sample decreases. We think that the phenomenon is attributed to the reduction of the number of oxygen defects in the sample heated at high temperature.
Group similarity based algorithm for network community structure detection
Authors: Yuan Chao  , Chai Yi  ,   Institute of Automation, Chongqing University, Chongqing 400030, China
Published: December 2020

Community structure has an important influence on the structural and dynamic characteristics of the complex system. In the present study, a group similarity model is proposed for the measurement of similarity between two communities. So it can help us understand the mechanism of inter action between these communities. Moreover, based on this model, a hierarchical clustering based algorithm for network community structure detection is put forward. By this algorithm, one pair of communities with the largest similarity is merged in each iteration. And then an evaluation function is adopted for choosing the optimal partition. The algorithm gives a higher performance than many state-of-the-art community detection algorithms when tested on a series of real-world and synthetic networks. Especially, it performs better when the edge density of the network is high.
Parameter determination based on composite evolutionary algorithm for reconstructing phase-space in chaos time series
Authors: Zhang Wen-Zhuan  , Long Wen  , Jiao Jian-Jun  ,   Guizhou Key Laboratory of Economics System Simulation, Guizhou University of Finance and Economics, Guiyang 550004, China
Published: December 2020

To improve the prediction accuracy of the chaotic time series prediction model, a composite optimization method of the differential evolution (DE) algorithm that is based on the phase space reconstruction and least square supported vector machine (LSSVM), is proposed. The phase space parameters and LSSVM model parameters are taken as differential evolution algorithm individuals while the prediction accuracy of the chaotic time series is used as the evaluation function of DE algorithm. The optimal parameters are obtained by mutation, crossover, and selection operators of DE algorithm. Several numerical simulation results show that not only four parameters are determined at the same time, but also the performance of chaotic time series prediction is improved.
The vibration and dissociation of NO onPt (111) surface
Authors: Lü Bing  , Linghu Rong-Feng  , Song Xiao-Shu  , Li Ying-Fa  , Yang Xiang-Dong  ,   School of Physics and Electronic Science, Guizhou Normal University, Guiyang 550001, China;,   School of Physics and Electronic Science, Guizhou Normal College, Guiyang 550018, China;,   Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, China
Published: December 2020

The absorption of NO on the Pt (111) surface is investigated based on the density functional theory and the periodic slab model. The absorption structure is analyzed through scanning tunneling microscopy (STM) image. The calculated Pt-NO stretching vibration (2) frequency is almost unchanged, and the frequencies of blocked translation (3, 4) and blocked rotation (5, 6) are completely degenerate. The dissociation processes of NO on Pt (111) surface are discussed in detail using the CI-NEB method. The results show that the dissociation of NO on Pt (111) surface is difficult and it must overcome 2.29 eV energy barrier to achieve it.
The effect of strain on band structure of single-layer MoS2: an ab initio study
Authors: Wu Mu-Sheng  , Xu Bo  , Liu Gang  , Ouyang Chu-Ying  ,   College of Physics and Communication Electronics, Jiangxi Normal University, Nanchang, Jiangxi 330022, China
Published: December 2020

We study the electronic properties of single-layer MoS2 with biaxial tensile strain by using an ab initio method of plane wave potential technique based on the density function theory. Our results show that a small tensile strain (0.5%) will result in the transition from direct to indirect gap for ingle-layer MoS2. With the increase of strain, the feature of the indirect gap can be preserved but the gap decreases linearly. Based on the further analysis of the density of states and the projected charge density for single-layer MoS2, the reason of the change of band structure is revealed.
The Borkhoffian expression of Boltzmann-Hamel equation of nonholonomic system and its generalized symplectic geometric algorithm
Authors: Xie Jia-Fang  , Pang Shuo  , Zou Jie-Tao  , Li Guo-Fu  ,   College of Science, North China University of Technology, Beijing 100144, China
Published: December 2020

For a Boltzmann-Hamel equation of nonholonomic mechanical system, when it meets certain conditions, the Boltzmann-Hamel equation can be transformed into a Birkhoffian system. By constructing the generating function, the system is investigated numerically using the generalized symplectic geometric algorithm of the nonautonomous Birkhoffian system. Compared with the above-mentioned algorithm with the classical Runge-Kutta method, Birkhoffian symplectic scheme is very accurate in a long-term tracing.
Nonlinear dynamics of 1550 nm vertical-cavity surface-emitting laser with polarization- preserved optical feedback
Authors: Zheng An-Jie  , Wu Zheng-Mao  , Deng Tao  , Li Xiao-Jian  , Xia Guang-Qiong  ,   School of Physical Science and Technology, Southwest University, Chongqing 400715, China
Published: December 2020

Based on the framework of the spin-flip model, the nonlinear dynamics of 1550 nm vertical-cavity surface-emitting laser (VCSEL) subject to polarization-preserved optical feedback is theoretically investigated. The results show that for a free-running 1550 nm-VCSEL, the current value for polarization switching (PS) is affected seriously by the internal parameters; with the increase of the gain anisotropy coefficient γa, the corresponding current for PS increases. Due to the introduction of the polarization-preserved optical feedback, the dominant polarized mode (Y polarized mode) will display different dynamical states for different injection currents while the other mode (X polarized mode) may be excited. As a result, the average output powers of the two polarized modes increase with fluctuation with the increase of current. For different feedback times, the dynamic states of 1550 nm-VCSEL with polarization- preserved optical feedback maybe route into chaos via different evolution paths such as period doubling bifurcation, quasi-periodic bifurcation and intermittent chaos.
Experimental study on an X-band coaxial multi-beam relativistic klystron amplifier
Authors: Liu Zhen-Bang  , Jin Xiao  , Huang Hua  , Chen Huai-Bi  , Wang Gan-Ping  ,   Department of Engineering Physics, Tsinghua University, Beijing 100084, China;,   Institute of Applied Electronics, Science and Technology on High Power Microwave Laboratory, China Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

The advantages of the tri-axial relativistic klystron amplifier and the multi-beam klystron amplifier are analyzed, and then an X-band coaxial multi-beam relativistic klystron amplifier is designed in order to increase the output microwave power and frequency. Based on the results from partial-in-cell simulation, the experiment is performed on the Sinus accelerator. In experiment, the transmission and bunching of electron beam are analyzed, and then the amplifier is driven by a beam of 5.3 kA at 670 kV, and the maximum output power is 420 MW when input power is 30 kW, and frequency is 9.375 GHz. The experiment proves that a ten kW-level input power can drive the X-band coaxial multi-beam relativistic klystron amplifier to generate more than one hundred MW-level output power.
Analysis of high frequency characteristics of the double-grating rectangular waveguide slow-wave-structure based on the field match method
Authors: Liu Qing-Lun  , Wang Zi-Cheng  , Liu Pu-Kun  , Dong Fang  ,   Key Laboratory of High Power Microwave sources and Technologies, Institute of Electronics, Chinese Academy of Sciences, Beijing 100190, China;,   Space Traveling Wave Tube Research and Development Center, Institute of Electronics, Chinese Academy of Sciences, Beijing 100190, China;,   Graduate University of Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

A mode analysis is presented for the double-grating rectangular waveguide slow-wave structure (SWS) with arbitrary longitudinal displacements between the two gratings. By matching boundary conditions along the sides of the gratings, the distribution of electromagnetic field and high frequency characteristics of the SWS are studied. The simulation results show that the dispersion curve deduced from field equations is in good agreement with that simulated by software while the interaction impedance is higher than that calculated by HFSS, but lower than by CST. It also demonstrates that the longitudinal displacement between two gratings has a great effect on the first stop-band. The upper cutoff frequency of the first mode almost overlaps the lower cutoff frequency of the second mode when the displacement is set to be strictly half period, that is to say, the first stop-band disappears. To avoid the mode degeneracy and competition, the displacement is reduced to be about 0.45 times of period, so that with the interaction impedance kept unchanged, the stop-band increases about 7.9GHz, while the pass-band declines about 2.8 GHz.
Numerical simulation of droplet impact onto liquid films with smoothed particle hydrodynamics
Authors: Ma Li-Qiang  , Liu Mou-Bin  , Chang Jian-Zhong  , Su Tie-Xiong  , Liu Han-Tao  ,   School of Mechatronice Engineering, North University of China, Taiyuan 030051, China;,   Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China
Published: December 2020

In this paper, we present a modified smoothed particle hydrodynamics (SPH) method. In order to well predict the morphology change of liquid drop, the presented SPH method employs a kernel gradient correction and a coupled solid boundary treatment algorithm. An inter-particle interaction force is used to model surface tension, and an artificial stress model is used to deal with tensile instability. The process of droplet impacting on liquid film is numerically simulated by the modified SPH method, which can well predict the pressure field evolution process of the drop impacting onto the liquid film and capture the variation of the free surface at different instants. Effects of Web number and surface stress on droplet impacting are also investigated, and mechanism of droplet splashing is analyzed. It is clearly demonstrated that the modified SPH method can effectively describe the dynamics of droplet splashing and the variation of the free surface. The obtained liquid drop morphology accords well with the results from other sources.
Measurement of gain coefficients of stimulated Brillouin scattering in water at different temperatures
Authors: Chen Wei  , Chen Xue-Gang  , Shi Jiu-Lin  , He Xing-Dao  , Mo Xiao-Feng  , Liu Juan  ,   Key Laboratory of Nondestructive Test (Ministry of Education), Nanchang Hangkong University, Nanchang 330063, China
Published: December 2020

In this paper, the influences of medium temperature on threshold and gain coefficient of stimulated Brillouin scattering (SBS) in water are investigated theoretically and experimentally. Based on the theoretical analysis, a new method is proposed to determine the gain coefficient of SBS of the material by measuring the threshold. The experimental results indicate that the gain coefficient of SBS increases exponentially with the increase of medium temperature.
The effect of interchain coupling on inelastic scattering of oppositely charged polarons
Authors: Di Bing  , Wang Ya-Dong  , Zhang Ya-Lin  ,   College of Physics, Hebei Advanced Thin Films Laboratory, Hebei Normal University, Shijiazhuang 050016, China;,   Zhangjiakou Vocational and Technical College, Zhangjiakou 075051, China
Published: December 2020

Within an one-dimensional tight-binding Su-Schreiffer-Heeger model, we investigate the effect of interchain coupling on inelastic scattering of oppositely charged polarons in conjugated polymer by using a nonadiabatic evolution method. It is found that the yield of the neutral exciton depends sensitively on the interchain coupling. The yield of the neutral exciton increases with the enhancement of overlapping which can make the wave functions of oppositely charged polarons more largely overlapped. The formation yield of excitons also increases with the number of overlapping sites increasing to its maximum value, where the length of overlapping sites is almost of the same order of magnitude as the width of the polaron, the reason is that the number of overlapping sites can affect the overlap of oppositely charged polaron wave functions. In turn, the charge transfer between them depends on the overlap of their wave functions. Therefore, when the size of overlapping sites is almost of the same order of magnitude as the width of the polaron, their wave functions have a largest overlap, thereby making charge transfer more easily. So the yield of excitons has the largest value.
Photon-assisted electron spin tunnelling in double-well potential
Authors: Li Chun-Lei  , Xu Yan  , Zhang Yan-Xiang  , Ye Bao-Sheng  ,   Laboratory for Micro-sized Functional Materials, College of Elementary Education, Capital Normal University, Beijing 100048, China
Published: December 2020

Within the framework of the single-band effective mass approximation method, the Floquet theorem, and the transfer-matrix technique, we investigate single-electron photon-assisted tunnelling in a double-well potential with the time-periodic field and Rashba and Dresselhaus spin-orbit coupling. The transmission probability displays statellite peaks on both sides of the field-free resonant peaks. The results show that the single-electron spin tunnelling can be controlled through changing the structure of the double-quantum-well and the intensity of the applied electric field. These advantages are useful for optimizing the semiconductor spintronic devices.
Threshold voltage analytical model of fully depleted strained Si single Halo silicon-on-insulator metal-oxide semiconductor field effect transistor
Authors: Xin Yan-Hui  , Liu Hong-Xia  , Fan Xiao-Jiao  , Zhuo Qing-Qing  ,   Key Laboratory for Wide Band Gap Semiconductor Materials and Devices of Education, School of Microelectronics, Xidian University, Xi’an 710071, China
Published: December 2020

A single Halo fully depleted strain Si Silicon-On-insulator (SOI) structure, which has the advantages of strained Si, Halo doping, and SOI structure, is proposed to improve driving current, suppress the short channel effect (SCE) and drain induced barrier lowering (DIBL) effect. A two-dimensional analytical model for the surface potential, the surface electric field and the threshold voltage is proposed by solving Poisson's equation. The effects of Ge fraction in the relaxed layer on surface potential and threshold voltage are investigated. In the paper we analyze the influence of drain voltage on surface potential. Finally the effects of Halo doping on threshold voltage and DIBL are investigated. The results show that the novel device can suppress the short channel effect and DIBL effect, and increase carrier transport speed.
Stability of low temperature and transparent amorphous InGaZnO thin film transistor under illumination
Authors: Li Xi-Feng  , Xin En-Long  , Shi Ji-Feng  , Chen Long-Long  , Li Chun-Ya  , Zhang Jian-Hua  ,   Key Laboratory of Advanced Display and System Applications of Ministry of Education, Shanghai University, Shanghai 200072, China
Published: December 2020

The amorphous indium-gallium-zinc-oxide (a-IGZO) thin films are prepared by radio frequency magnetron sputtering at ambient temperature. The transparent thin film transistors (TFT) fabricated at low temperature (a-IGZO active channel exhibits good electrical properties with a field effect mobility of around 10 cm2·V-1·s-1, subthreshold swing of 0.4 V/decade, and high Ionoff current ratio of over 107. Hysteresis is not observed when gate voltage sweeps forward and reverses. And the dependence of white LED illumination on characteristic of a-IGZO TFT is investigated. The results show that output characteristic is hardly affected, indicating the potential of the devices for transparent electronics In particular, illumination stability is investigated under white LED illumination stress test, and the a-IGZO TFT shows only 04 V shift in threshold voltage. The negative shift can be explained on the basis of trap of interface state.
Experimental diagnostic of melting fragments under explosive loading
Authors: Chen Yong-Tao  , Ren Guo-Wu  , Tang Tie-Gang  , Hu Hai-Bo  ,   Laboratory for Shock Wave and Detonation Physical Research, Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

We have conducted experiments to study the melting fragments from explosively shocked melting Pb targets. Based on the traditional Asay-Window technique, Asay-F-window was designed, which is suitable to investigate high-density melting fragments of metal sample. The areal mass and volume density of melting fragments from the Pb target were presented, which is also compared with that of micro-jetting and solid spallation. The results may contribute to the understanding of physical mechanism and construction of dynamic model for melting fragments. Additionally, the Asay-F-Window technique is an effective supply for proton photography technique to study the dynamic fragmentation of melting metal.
A class of topologically conjugated chaotic maps of tent map to generate independently and uniformly distributed chaotic key stream
Authors: Xu Zheng-Guang  , Tian Qing  , Tian Li  ,   School of Automation, University of Science and Technology Beijing, Beijing 100083, China;,   School of Astronautics, Beijing University of Aeronautics and Astronautics, Beijing 100091, China
Published: December 2020

In this paper, a class of topologically conjugated maps of tent map is established, and the sampling rule is proved to generate the independently and uniformly distributed key streams. One example is given to show that the established chaotic system does not converge into zero in each parameter due to its nonlinear characteristic. Another example with different initial values and lengths of sequence is illustrated, in which the chaotic key stream generated by the proposed theorem is independently and uniformly distributed chaotic system and can successfully satisfy the randomness requirements in Federal Information Processing Standard 140-2(FIPS PUB 140-2) and National Institute of Standards and Technology Special Publication 800-22 (NIST SP800-22) test. The result in this paper can provide the theoretical foundation and more selections of systems to generate independently and uniformly distributed chaotic key stream.
Multiscale multivariate fuzzy entropy analysis
Authors: Li Peng  , Liu Cheng-Yu  , Li Li-Ping  , Ji Li-Zhen  , Yu Shou-Yuan  , Liu Chang-Chun  ,   School of Control Science and Engineering, Shandong University, Jinan 250061, China;,   College of Science and Technology, Shandong University of Traditional Chinese Medicine, Jinan 250355, China
Published: December 2020

Multiscale multivariate sample entropy can test the multivariate complexity, which is accepted as a kind of reflection of nonlinear dynamical interactions in multichannel data. It is however relatively unstable due to the rigid ranking scheme used in comparison among different patterns. It is not applicable to the nonlinear and non-stationary data because the multiscale framework used is in fact handled by moving average succeeded by down-sampling, which actually has a premise of stationary data. We substitute a fuzzy membership function for the original rigid one and compare the performances of different kinds of fuzzy membership functions. In addition, we employ the multivariate empirical mode decomposition (MEMD) to capture different scales. Results show that the substitution of fuzzy membership function brings in significant stability. It is much more obvious by using the introduced physical fuzzy membership function (PFMF). Also MEMD could capture scales more robustly. In conclusion, the introduced PFMF- and MEMD-based MMFE perform best. Final analysis on the interactions between heart rate variability (HRV) and heart diastolic time interval variability (DIV) validates it. In addition, the results show that the multivariate complexity between HRV and DIV decreases in aging or heart failure group but in a distinctly different decreasing manner–it deceased at low scales with aging, indicating a loss of short-range correlation but both at low and high scales with heart failure, which shows the losses of both short- and long-range correlations. Studies in noninvasive detection of cardiovascular diseases should benefit from the above conclusions.