bluuebunny/crossref_metadata_2025 huggingface dataset:
First-principles calculations of ZnO polar surfaces and N adsorption mechanism
Authors: Li Qi  , Fan Guang-Han  , Xiong Wei-Ping  , Zhang Yong  ,   华南师范大学光电子材料与技术研究所,广州 510631
Published: December 2020

Structural and electronic properties of clean polar ZnO surfaces are studied by using the first-principles ultra-soft pseudo-potential approach to the plane wave, based on the density functional theory. Furthermore, the relaxations, bandstructures, and densities of states for ZnO(0001) and ZnO(0001) surfaces and the N adsorption for ZnO(0001) surface are studied. The calculation results reveal that the relaxation of ZnO(0001) surface is stronger than that of ZnO(0001) surface, so ZnO(0001) surface has a better integrity. Compared with the ZnO bulk, the ZnO(0001) surface has a narrow bandgap, and big conductivity due to the delocalizing characters. However, the bandgap of the ZnO(0001) surface widens, the empty energy levels appear near the top of bandgap due to the existence of O-2p states, and the body electrons transite easily to the surface, under the thermal excitation, and resulting in negative charges.We find that the face-centered site is the stablest adsorption position of ZnO (0001) surface, and the formation energy is lowest in the first layer when N atoms are embeded in the ZnO (0001) surface. Therefore, N atoms easily accumulate on the surface layer rather than occupy the positions in the body.
Magneto-tunneling effect in weakly coupled GaAs/AlGaAs/InGaAs double quantum well tunneling structure
Authors: Zhou Yuan-Ming  , Yu Guo-Lin  , Gao Kuang-Hong  , Lin Tie  , Guo Shao-Ling  , Chu Jun-Hao  , Dai Ning  ,   中国科学院上海技术物理研究所红外物理国家重点实验室,上海  200083
Published: December 2020

We report on the magnetic tunneling properties of weakly coupled GaAs/AlGaAs/InGaAs double quantum well tunneling structure at low temperature (15 K) in a magnetic field applied parallel to the tunneling current. The device is in resonance at zero bias voltage. From an analysis of the oscillations in magneto-conductivity for different bias voltages, the change in ground-state energy levels in two quantum wells with the bias can be confirmed and thus the tunneling mechanism was studied. The results reported in this paper provide the basis for the successful fabrication of weakly coupled double quantum dot system.
Effect of size-dependent elastic constants on electrical properties of strain silicon nanowires
Authors: Zhang Jia-Hong  , Gu Fang  , Liu Qing-Quan  , Gu Bin  , Li Min  ,   (1)南京信息工程大学电子与信息工程学院，南京  210044; (2)南京信息工程大学数理学院，南京  210044
Published: December 2020

Starting from the Keating model, a semi-continuum atomistic lattice model, with directly taking into account the discrete nature in width and thickness direction, is proposed to calculate the elastic constants and Youngs modulus of single crystal silicon nanowires (SiNWs). Based on the six-band k·p theory and the deformation potential concept, and taking into account the quantum-size effect and spin-orbit coupling, a numerical model for the valence band structures of SiNWs in various transport orientations is established by using the finite difference method. Then we use a top-of-the-barrier ballistic field-effect transistor (FET) model to investigate the effects of the uniaxial stress and the elastic constants on ballistic transport properties of the p-type SiNW FETs in combination with the calculation results from the two models mentioned above. It is found that the elastic constants and Youngs modulus of the SiNW are highly size-dependent, which is in good agreement with the available molecular dynamics result. Furthermore, our calculations indicate that the effect of size-dependent elastic constants on ballistic transport current of the SiNW FET strongly depends on the effect of the uniaxial stress on ballistic transport current, because when the uniaxial stress induces a significant change in valence band structures of SiNWs, the size-dependent elastic constants can obviously modify the valence band structure.
Research of in-situ electrical property of micron dimension ZnO under high pressure
Authors: Wu Bao-Jia  , Han Yong-Hao  , Peng Gang  , Liu Cai-Long  , Wang Yue  , Gao Chun-Xiao  ,   (1)吉林大学超硬材料国家重点实验室，长春  130012; (2)吉林大学超硬材料国家重点实验室，长春  130012；延边大学理学院，延吉  133002
Published: December 2020

Using the diamond anvil cell（DAC）method and the technology of sputtered film， photoetch and chemical etching， the conductivity of micron dimension ZnO were measured successfully under high pressure with molybdenum electrodes on DAC. The samples conductivity was minimal at 919 GPa pressure， which showed the beginning of structural phase transition from wurtzite to rocksalt. Contining compression as far as 1122 GPa， the conductivity increased rapidly and then slowly， which indicated the phase transformation pressure spot was 1122 GPa and the whole example was of rocksalt structure. In addition， it was found that the oxygen holes caused conductivity change by experimentally comparing the samples annealed at 500 ℃ in air， in argon and unannealed respectively.
Temperature-dependent Raman property of n-type SiC
Authors: Han Ru  , Fan Xiao-Ya  , Yang Yin-Tang  ,   (1)西安电子科技大学微电子学院,西安  710071; (2)西北工业大学计算机学院，航空微电子中心,西安  710072
Published: December 2020

Micro-Raman scattering from the nitrogen doped n-SiC is performed at the temperatures ranging from 100 to 450 K. The temperature dependences of the first-order Raman scattering, electronic Raman spectra and the second-order Raman features are obtained. These measurements reveal that most of the first-order Raman phonon frequencies decrease with temperature increasing, but the redshifts of the acoustic phonon modes are smaller than those of the optical phonon modes. Meanwhile, the longitudinal optical phonon-plasma coupled (LOPC) mode manifests different features with temperature increasing. The LOPC mode tends to have a blueshift at a lower temperature but a redshift at a higher temperature. This indicates that the temperature dependence of LOPC mode is affected not only by the anharmonic effects, but also by the ionized donor concentration. With the increase of the measurement temperature, the intensity of the electronic Raman spectrum decreases, and the linewidth gradually broadens, but the electronic Raman signal is almost not shifted. The redshift of the second-order Raman spectrum is smaller than that of the first-order Raman spectrum, but the intensity of the second-order Raman spectrum substantially decreases with the increase of temperature.
Composition, microstructure and properties of C-N-V films prepared by pulsed bias arc ion plating
Authors: Li Hong-Kai  , Lin Guo-Qiang  , Dong Chuang  ,   大连理工大学三束材料改性教育部重点实验室，大连 116085
Published: December 2020

High quality C-N-V films with different compositions were prepared on cemented carbide substrate using pulsed bias arc ion plating. The surface morphology, composition, microstructure and properties of C-N-V films were investigated by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, Raman spectra, grazing incident X-ray diffraction, and nano-indentation, respectively. The results show that the deposited films were nanocomposite films with VN nanocrystalline phase imbedded within diamond-like carbon(DLC) amorphous matrix. The hardness and elastic modulus, which are closely related to the composition and structure of the film, first increase and then decrease with increasing V and N contents and have the highest values of 368 and 5697 GPa exceeding that of pure DLC film prepared under the same condition when nitrogen content is 204% and vanadium content is 218%. The variation of V and N contents has significant influence on the phase structure, relative concentration of VN crystalline phase and DLC amorphous phase, and induces the formation of nano-diamond phase, hence has great effect on the properties of the films.
Influence of Fe-B pairs on minority carrier lifetime, trapping density and internal quantum efficiency in mono-crystal Si solar cells
Authors: Li Feng  , Ma Zhong-Quan  , Meng Xia-Jie  , Yin Yan-Ting  , Yu Zheng-Shan  , Lü Peng  ,   (1)上海大学物理系，上海  200444; (2)上海索朗太阳能科技有限公司，上海  200120
Published: December 2020

Solar-grade p-type Czochralski silicon wafers are doped with phosphorus by single-face and double-face diffusions, and the influence of Fe-B pairs on the minority carrier lifetime, the trapping centers density and the internal quantum efficiency （IQE） of cells （fabricated from the wafers） is analyzed by measuring microwave-detected photo-conductance decay minority carrier lifetime. In the doped wafers with single-face diffusion, the minority carrier lifetime is determined mainly by the density distribution of Fe-B pairs. However, in the doped wafers with double-face diffusion, the minority carrier lifetime is less influenced by the concentration distribution of Fe-B pairs than by other impurities and defects. Numerical calculation based on the combination of the transient voltage signal and the trapping model indicates that the density of trapping centers is reduced by either of diffusion process. On the other hand, detailed analysis of selected specific spots in one wafer with single-face diffusion shows that Fe-B pairs are not the major factor influencing the density of trapping centers. The wafers with different diffusion processes are fabricated into c-Si solar cells and the IQE is measured by using a light beam induced current. The results show that the IQEs of cells with double-face diffusion are higher than those with single-face diffusion, which demonstrates the negative effect of Fe-B pairs on the IQE of solar cells.
Influence of n-type layer structure on performance and light-induced degradation of n-i-p microcrystalline silicon solar cells
Authors: Lu Peng  , Hou Guo-Fu  , Yuan Yu-Jie  , Yang Rui-Xia  , Zhao Ying  ,   (1)河北工业大学信息工程学院，天津  300130; (2)南开大学光电子薄膜技术与器件研究所，天津  300071; (3)南开大学光电子薄膜技术与器件研究所，天津  300071；河北工业大学信息工程学院，天津  300130
Published: December 2020

A series of n-i-p microcrystalline silicon thin film solar cells with different values of crystalline volume fraction Xc of n-type layers are prepared by radio frequency plasma enhanced chemical vapor deposition. It is found that the structure of intrinsic layer is strongly dependent on the structure of n-type layer, especially the incubation layer thickness at n/i interface and Xc of intrinsic layer. This series of solar cells were light-soaked under 100 mW/cm2 for 400 h. The experiment results demonstrate that the solar cell with the highest Xc of intrinsic layer (Xc(i)=65%) has the lowest light-induced degradation ratio. Then the solar cell with n-type layer deposited in an amorphous silicon/microcrystalline silicon transition region (Xc(i) =54%) is light-soaked under the irradiations of white light, red light and blue light with the same light intensities, separately. After 400 h light-soaking, the light degradation ratio is only 2% for the red light irradiation, while it is 8% for the blue light irradiation.
Fast single-stranded desoxyribonucleic acid sequencing between polynucleotide molecules
Authors: Jiang Shao-Chuan  , Zhang Lin-Xi  , Xia A-Gen  , Chen Hong-Ping  ,   (1)温州大学物理系，温州  325027; (2)浙江大学物理系，杭州  310027
Published: December 2020

The dynamics of the translocation of single-stranded desoxyribonucleic acid (DNA) chains through a nanopore under the driving of an applied field is studied by three-dimensional Langevin dynamics simulations. It was found that different monomers correspond to different residence times. With the increase of the length of nanopore, the difference in residence time becomes smaller and smaller. Based on the simplified model, a new method is proposed to discriminate between the poly(dA) and poly(dC) of single-stranded DNA chains by recording the residence time of monomer. The method is utilized to predict the sequence of seventeen different chains, and the average accuracy is about 951%. If the residence time of monomer can be well recorded in the DNA translocation experiment, the sequence of the whole DNA will be predicted once and for all. With the improvement of the method, it will provide a low-cost high-throughput way to predict the sequence of DNA.
The trend of seismic activities in China and adjacent regions after Wenchuan earthquake——Research of seismic energy release with “oscillation analogy”
Authors: Hu Wei-Jian  , Sang Hong  , Liu Hui-Juan  , Wang Fu-Yun  , Li Ping-Lin  ,   (1)郑州大学物理工程学院,郑州 450001; (2)中国地震局地球物理勘探中心,郑州 450002; (3)中国地震应急搜救中心,北京 100049
Published: December 2020

According to the geological structure and characteristics of seismic activity in the eastern segment of Eurasian seismic zone, China and adjacent regions are chosen as the research regions, where earthquakes of Ms≥60 happened 824 times in total from 1897 to 2008 The sum of the yearly released energy is filtered and studied systematically. The results show that the release of seismic energy features a periodic damped oscillation. Through the oscillation analogy, we can forecast quantitatively the long-term and medium- and short- term seismic situations in China and adjacent regions. Theoretical analysis confirms that the earthquake vibrancy in the continental plates should last 1537 a, namely, 1897—2050 Such a result is consistent with the conclusions from the analysis of Chinese historical seismic data collected for more than 2000 a, and it may be regarded as a theoretical basis that the periodic seismic activity lasts about 150 a in China and adjacent regions. According to the periodic characteristic of the seismic activity, we can forecast theoretically that the current active duration will close in 2010—2012, furthermore, the next active duration will begin near 2020—2021, and then end in 2040 around. Subsequently, the earthquake process will completely enter into a relatively quiet duration for over one century after 2050
The theoretical measurement error of a novel static polarization wind imaging interferometer
Authors: Liu Ning  , Zhang Chun-Min  , Wang Jin-Chan  , Mu Ting-Kui  ,   西安交通大学理学院，非平衡物质结构与量子调控教育部重点实验室，西安 710049
Published: December 2020

The principle of a novel static polarization wind imaging interferometer is described, and the Jones matrix of the system is derived in general case. The theoretical measurement errors of the wind and temperature, introduced by some important parameter errors of all the polarization components in the system, is calculated and analyzed by computer simulation. The tolerances of the parameters are proposed according to accuracy of the system. The study provides a theoretical basis and practical guidance for the development, calibration and data post-processing of the novel static polarization wind imaging interferometer.
Thermomigration in micro interconnects in integrated circuits
Authors: Zhang Jin-Song  , Wu Yi-Ping  , Wang Yong-Guo  , Tao Yuan  ,   (1)华中科技大学材料科学与工程学院，武汉  430074; (2)上海大学机电工程与自动化学院，上海  200072
Published: December 2020

With the reduction of feature size of integrated circuits, higher current density has been introduced in electronic devices which produces a significant Joule heating effect. This also brings about an increase of the temperature which induces a very high temperature gradient in some local regions of micro interconnects. As a result, thermomigration will occur and metal atoms will move opposite to the direction of the temperature gradient. Thermomigration is one of common modes in reliability failures in electronic devices. This paper reviews and analyzes the previous researches on the thermomigration theory and experiment in stripe and solder interconnects under the temperature loading and the current/temperature loading. The challenges of thermomigration are discussed for interconnects in electronic devices in the future.
Shock position for a class of Robin problems of singularly perturbed nonlinear equation
Authors: Mo Jia-Qi  , Liu Shu-De  , Tang Rong-Rong  ,   (1)Department of Mathematics,Anhui Normal University,Wuhu 241000,China; (2)Faculty of Science, Huzhou Teachers College, Huzhou 313000, China
Published: December 2020

The expressions of shock solutions for singularly perturbed Robin problem of nonlinear equations are constructed using the matching method. The conditions for appearance of shock near the boundary are discussed.
Instantaneous embed soliton and instantaneous taper-like soliton for the (3+1)-dimensional Burgers system
Authors: Ma Song-Hua  , Fang Jian-Ping  , Ren Qing-Bao  ,   Department of Physics, Lishui University, Lishui 323000, China
Published: December 2020

With a projective equation method and a variable separation method, new families of variable separation solutions (including solitory wave solutions, periodic wave solutions, and rational function solutions) for (3+1)-dimensional Burgers system is derived. Based on a derived solitory wave solution and a rational function solution, we obtain some novel localized structures such as instantaneous embed soliton and instantaneous taper-like soliton.
Interval diffracted particle filter
Authors: Ning Xiao-Lei  , Wang Hong-Li  , Zhang Qi  , Chen Lian-Hua  ,   The Second Artillery Engineering College, Xi'an 710025,China
Published: December 2020

A new particle filter based on interval filter and particle diffraction is proposed for the on-line estimation of non-Gaussian and nonlinear system with uncertain dynamics modeling. This algorithm computes the more accurate importance density function, which integrates the latest observations into the system state transition density, so that the approximation to the system posterior density is improved. At the same time, the workload of calculation is reduced by treating particle diffraction like light diffraction. A simulation experiment on the SINS/CNS (strap-down inertial navigation system/celestial navigation system) attitude estimation shows the effectiveness and robustness of the improved algorithm.
Symmetries and conserved quantities of the Rosenberg problem
Authors: Zhang Yi  , Xue Yun  , Ge Wei-Kuan  ,   (1)Department of Civil Engineering, University of Science and Technology of Suzhou, Suzhou 215011, China; (2)Department of Physics, Huzhou Teachers College, Huzhou 313000, China; (3)School of Mechanical and Automation Engineering, Shanghai Institute of Technology, Shanghai 200235, China
Published: December 2020

The Rosenberg problem is a typical but not a too complex problem of nonholonomic mechanical systems. By using the theory of Noether symmetries of nonholonomic systems, the conserved quantities of the problem is successively deduced,and the final result is obtained.
The canonical transformation and symplectic description in mechanics, thermodynamics and electromagnetic waveguide
Authors: Yang Hong-Wei  , Zhong Wan-Xie  , Hou Bi-Hui  ,   (1)College of Mathematics & Physics, Beijing University of Technology, Beijing 100124, China; (2)Research Institute of Engineering Mechanics, Dalian University of Technology, Dalian 116023,China
Published: December 2020

The symplectic description and transformed condition of canonical transformation are discussed in mechanics. The condition in thermodynamics is proved. The canonical transformation in electromagnetic waveguide is also studied. The conclusion shows that mechanics, thermodynamics and electromagnetic waveguide have a similar structure in symplectic system. It presents a useful attempt to unified theories.
Performance characteristics of an irreversible engine consisting of nonlinear diodes system
Authors: Wang Xiu-Mei  , He Ji-Zhou  , He Xian  , Xiao Yu-Ling  ,   Department of Physics, Nanchang University, Nanchang 330031, China
Published: December 2020

The performance of an irreversible engine consisting of a nonlinear diodes system is presented. The system consists of two diodes switched in the opposite directions and located in two reservoirs at different temperatures, and the two diodes are connected in parallel with a capacitor. Based on the theory of thermal fluctuations, the expressions of the heat fluxes absorbed from the hot and cold reservoirs are derived. When the heat leak between the two reservoirs is taken into account, the power output and the efficiency of the engine can be obtained. The performance characteristic curves are plotted and the characteristic relations between the optimum performance parameters and the ratio of the temperatures are obtained by numerical simulation. The influence of the main parameters, including the nonlinearity of the diodes, the loss of heat leak and the ratio of temperatures of two reservoirs, on the performance characteristics of the engine is analyzed in detail. Finally, the performance characteristics of the ideal diodes engine are discussed.
Scaling analysis on electroencephalogram and its application to sleep-staging
Authors: Ma Qian-Li  , Bian Chun-Hua  , Wang Jun  ,   Institute for Biomedical Electronic Engineering, Key Laboratory of Modern Acoustics of Ministry of Education, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, China;,   Institute for Biomedical Electronic Engineering, Key Laboratory of Modern Acoustics of Ministry of Education, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, China; Key Laboratory of Image Processing and Image Communicati;,   Key Laboratory of Image Processing and Image Communication of Jiangsu Province, School of Geography and Biological Information, Nanjing University of Posts and Telecommunications, Nanjing 210003,China
Published: December 2020

Electroencephalogram (EEG) shows long-range power-law and multifractal scaling behaviors, which varies with physiological and pathological conditions. In the present paper, the scaling behavior of sleep EEG is studied using monofractal detrended fluctuation analysis (DFA) and multifractal singularity spectrum. It is found that, the DFA scaling exponent α is more sensitive to the differences between EEG derivations and subject groups, but irregular with sleep stages. However, the variation of multifractal singularity strength range Δα with sleep stages is more regular, it increases constantly from sleep stage Ⅰ to stage Ⅳ, showing less difference between EEG derivations and subject groups. Thus, it is suggested that multifractal parameter Δα is more suitable than monofractal scaling exponent α to be used as a quantitative parameter for sleep staging.
Coherence bi-resonance in a two-dimensional neural map
Authors: Wang Mao-Sheng  , Huang Wan-Xia  , Cui Zhi-Feng  ,   Department of Physics, Anhui Normal University, Wuhu 241000,China
Published: December 2020

The influence of noise on the dynamics of a two-dimensional neural map with self-sustained subthreshold oscillations is studied by numerical simulation. When the injected current is absent and the control parameter is located in the silence region, numerical results show that stochastic oscillations of the membrane potential can be induced by noise. Moreover, the coherence of such oscillations shows two maxima with the variation of the noise strength. The effect of control parameter on the dynamics of the system has also been investigated. Interestingly, it is found that the occurrence of coherence bi-resonance is closely associated with the distinct characteristics of the bifurcation of the deterministic dynamics.
The cellular automaton model of traffic flow based on the driving behavior
Authors: Zheng Liang  , Ma Shou-Feng  , Jia Ning  ,   Systems Engineering Institute, School of Management, Tianjin University, Tianjin 300072, China
Published: December 2020

On the basis of the research of driving behavior, by analyzing the mechanism of driving behavior and using the cellular automaton (CA) model, we introduce the mechanism of driving behavior, which is associated with the vehicle’s own speed, the relative speed, the vehicle spacing, and the safety vehicle spacing, into the CA model (ACA). We observe the metastability, phase-separation and hysteresis phenomena when taking advantage of ACA model to conduct the microscopic traffic simulation and compare the simulation results of ACA model with the simulation results of the CA model (BCA) which only considers the vehicle’s own speed and the vehicle spacing. The results show that, in the macro level, from the maximum traffic flow, stability and the efficiency in dissolving congestions, the simulation results of ACA model exhibit a larger maximum value of flow which is also closer to the actual measured data, stronger stability and higher efficiency of dissolving jam; in the micro level, from the fluctuations of the vehicles’ speed and the vehicles’ headway-distance, the simulation results of ACA model exhibit that the vehicles do not accelerate or decelerate suddenly, the vehicles can be relatively and evenly distributed on the road. All these results illustrate that the relative speed and safety vehicle spacing have a significant impact on the driving behavior and also explain that the ACA model is in better consistence with the actual situation and has some practical significance.
The equation of state of H2+He fluid mixture in the region of partial dissociation
Authors: Gu Yun-Jun  , Zheng Jun  , Chen Zhi-Yun  , Chen Qi-Feng  , Cai Ling-Cang  ,   National Key Laboratory of Shock Wave and Detonation Physics Research, Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

The H2+He fluid mixture will be dissociated into a three-component mixture composed of H2 molecules, H and He atoms at high temperatures and high pressures. The dissociation energy of H2 molecule will be lowered due to the interactions between all these particles. In this paper, the self-consistent fluid variational theory is used to calculate the equation of state of H2+He fluid mixture in the region of partial dissociation, in which the various interactions between particles and the correlation contributions to the dissociation energy caused by both the temperature and pressure effects are taken into account. The dissociation degree and thermodynamic parameters are obtained from nonideal dissociation equilibrium, which is determined self-consistently by the free energy function. Comparison was made with the available shock-wave experiments, other theoretical calculations and Monte Carlo simulations.
A broadband supercontinuum generated by helium atom exposed to combined mid-infrared laser field
Authors: Chen Dong  , Yu Ben-Hai  , Tang Qing-Bin  ,   College of Physics and Electronic Engineering, Xinyang Normal University, Xinyang 464000, China
Published: December 2020

By solving the one-dimensional time-dependent Schr?dinger equation with split-operator method, we study the high harmonics generated by helium atom, and analyse the characteristics of the attosecond pulses generated by the high-order harmonics. By adopting a mid-infrared driving pulse (with wavelength of 2000 nm and pulse duration of 12.5 fs) combined with a short UV controlling pulse, a smooth supercontinuum with the bandwidth of 230 eV is observed. By adjusting the delay between the mid-infrared and ultraviolet fields, the contribution of the short quantum trajectory can be efficiently enhanced and an isolated 100 as pulse seems achievable. We found that the supercontinuum is not sensitive to the intensities of the two lasers, which facilitates the experimental implementation for the isolated attosecond pulse generation.
Theoretical calculation of integral cross sections of rotational excitation for collisions in isotopes of He atom with Na2 molecule
Authors: Li Wen-Feng  , Linghu Rong-Feng  , Cheng Xin-Lu  , Yang Xiang-Dong  ,   (1)Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, China; (2)Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, China; School of Physics and Electronic Science,Guzhou Normal University, Guiyang 550001, China
Published: December 2020

Multiple hard-ellipsoid model is a theoretical model which can more accurately decribe collisions between He atom and Na2 molecule. In this paper, we adopted the multiple hard-ellipsoid model to calculate the integral cross sections of rotational excitation for collisions in 3He,4He,7He,10He-Na2 systems at different relative incidence energies. This study shows that we can improve the accuracy of the results by increasing the number of equipotential ellipsoid surfaces. Moreover, we find that the integral cross sections of rotational excitation change with the relative incidence energy and reduced mass of the system. Finally, at relative incidence energy of 100 meV, we investigate the influence of different regions of the intermolecular potential on integral cross sections of rotational excitation in 4He-Na2 collisions.
Linear transformer driven long pulse high power generator with higher repetition rate
Authors: Xiang Fei  , Tan Jie  , Zhang Yong-Hui  , Wang Gan-Ping  , Luo Min  , Cao Shao-Yun  , Kang Qiang  , Gong Sheng-Gang  , Luo Guang-Yao  , Li Chun-Xia  , Jin Hui  , Zhang Bei-Zhen  ,   Institute of Applied Electronics, China Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

The realization technique of modularization on the long pulse high power generator was expounded. The relation between the ferromagnetic dissipation of the linear transformer and the exciting magnetic current was analyzed. The main influential factors on the wave distortion from the primary pulse to the system output waveforms were discussed. Finally, through engineering experiments, a long pulse power electron beam of up to several gigawatt with repetition frequency of several dozen hertz and rise time of 40—50 ns was obtained. This paper gives a new idea for research on the modularization of the long pulse high power generator with higher repetition rate.
Effect of structure and size of laser spot on speckle contrast in laser scanning display
Authors: Chang Hong  , Yang Fu-Gui  , Dong Lei  , Wang An-Ting  , Xie Jian-Ping  , Ming Hai  ,   Key Laboratory of Optoelectronic Science and Technology of Anhui Province, Department of Physics,University of Science and Technology of China, Hefei 230026, China
Published: December 2020

Speckle contrast in laser scanning display system with circular and rectangular laser spot on screen was calculated. For scanning with circular laser spot, the speckle contrast reduces with the decrease of the diameter of laser spot when the diameter of the laser spot is lager than the correlation length of the screen. When the laser spot is about the same size of the correlation length of the screen, the speckle contrast becomes higher owing to the non-Gaussian speckle effect. If we continue to reduce the size of laser spot, because of the specular reflection the speckle contrast decreases quickly. To ensure enough scattering elements in laser spot, the laser spot is just narrowed in one direction. If the laser spot is narrowed in the scanning direction, the speckle contrast is reduced due to the reducing temporal correlation of speckle, while if the laser spot is narrowed in the other direction, speckle contrast changes slightly. For the circular laser spot, some experimental results are given.
Terahertz spectra and soft optical phonons of PbB4O7 crystal
Authors: Fu Pei-Zhen  , Hou Bi-Hui  , Wang Li  , Zhong Ren-Bin  , Wang Ya-Li  , Zhang Er-Pan  , Jian Yan-Zhen  ,   Center for Crystal Research and Development, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China;,   College of Applied Science, Beijing University of Technology, Beijing 100124, China;,   College of Materials Science and Optoelectronic Technology, Graduate University of Chinese Academy of Sciences, Beijing 100049, China;,   College of Materials Science and Optoelectronic Technology, Graduate University of Chinese Academy of Sciences, Beijing 100049, China; Center for Crystal Research and Development, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences,;,   Laboratory of Optical Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China;,   Terahertz Science and Technology Research Center, School of Physical Electronics, University of Electronic Science & Technology, Chengdu 610054, China
Published: December 2020

The terahertz(1012Hz)spectra, Raman spectra and infrared-visible-UV spectra are analyzed for PbB4O7 crystal sample. A resonance peak appears in the curve of the dielectric function ε(ν) in the frequency range of 0.25—2.5 THz. The analysis supports that soft optical phonons exist in PbB4O7 crystal from four aspects: 1) the change curve ε(ν) of the dielectric function satisfies the Lyddane-Sachs-Teller relation; 2) a strong Raman scattering peak appears in the vicinity of resonance frequency (3.10 THz); 3) absorption coefficient curve α(ν) meets the characteristics of polaritons; 4) the dispersion relation curve ν(k) of the photon transmitting from the crystal reveals a frequency gap. The soft optical phonon exists in PbB4O7 crystal, which means that the frequency curve of the photon transmitting from the crystal will suffer splitting when the condition of producing polariton is satisfied. And the dispersion curve splits a higher branch and a lower one. This may help us find a new method of changing the frequency of the photon.
Short-cut transformation from one-dimensional to three-dimensional interference pattern by holographic simulation
Authors: Wang Xia  , Wang Zi-Xia  , Lü Hao  , Zhao Qiu-Ling  ,   Institute of Photonic Information Technology, School of Mathematics and Physics, Qingdao University of Science & Technology, Qingdao 266061, China
Published: December 2020

One short-cut transformation from one-dimensional (1D) to three-dimensional (3D) spatial optical lattices is simulated and studied. By adding mirror-symmetric beams for 3 original beams, the interference patterns from 2D to 3D can be obtained. Furthermore, by selecting appropriate polarization of the interference beams, the 3D structure can become 1D layered structure, and the period of the layers can reach the sub-wavelength. This result offers an alternative method to produce 1D and 3D photonic crystals, especially for the fabrication of optical band gap structures.
Influence of ultraviolet pulse laser irradiation on fused silica anti-damage ability in high vacuum environment
Authors: Huang Jin  , Jiang Xiao-Dong  , Liu Hong-Jie  , Lü Hai-Bing  , Wang Hai-Jun  , Yuan Xiao-Dong  , Zheng Wan-Guo  ,   Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

In high vacuum environment of 10-3 Pa, using 355 nm pulsed ultraviolet(UV) laser we repeatedly raster scanning fused silica at energy density of under zero probability damage threshold, with the purpose of studying the change in anti-damage ability of fused silica after receiving different UV laser irradiation dosages in high vacuum. The damage measured after irradiation and increasing of damage pit indicate that the anti-damage ability of fused silica obviously drop, the degree of depression is more closely correlated with the irradiation time, while the influence of irradiation energy density is weak. The measurement of fluorescence excitation and X-ray photoelectron spectros copy proves that the increase of oxygen-deficiency in fused silica is the main cause, and the degree correlates with the received UV laser irradiation dosage.
Incoherently coupled screening photovoltaic spatial soliton pairs with a divider resistance
Authors: Ji Xuan-Mang  , Jiang Qi-Chang  , Liu Jin-Song  ,   (1)College of Optoelectronic Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China; (2)Department of Physics and Electronic Engineering, Yuncheng University, Yuncheng 044000, China
Published: December 2020

Steady-state incoherently coupled screening photovoltaic spatial soliton pairs are predicted for biased photorefractive crystal circuit with a divider resistance. All kinds of the incoherently coupled spatial soliton pairs can be obtained from this theory by adjusting the values of the divider resistance, the biased electric field and photovoltaic electric field, such as the incoherently coupled screening spatial soliton pairs in biased photorefractive crystal with or without a divider resistance, the photovoltaic spatial soliton pairs in open-circuit, the photovoltaic spatial soliton pairs in close-circuit with or without a divider resistance, the screening-photovoltaic spatial soliton pairs in biased photovoltaic-photorefractive crystal with or without a divider resistance. Previous theories advanced individually elsewhere for these soliton pairs can be obtained by simplifying this theory under appropriate conditions.
Centerline characteristic scales of a turbulent plane jet and their dependence on filtration of measured signals
Authors: Mi Jian-Chun  , Feng Bao-Ping  ,   State Key Laboratory of Turbulence & Complex Systems, College of Engineering, Peking University, Beijing 100871, China
Published: December 2020

This study has two main objectives: (1) to examine the availability of a filtering scheme developed by Mi et al (2005, Phys. Rev. E 71, 066304) on the measured velocity signal and (2) to investigate the centerline characteristic scales of a plane jet with the exit Reynolds number of Re = 13188. The success of the filtering scheme has been well validated. It is found that the existence of the high-frequency noise impairs not only the small-scale properties of turbulence but also those associated with large-scale turbulence. After filtering the noise, while the dissipation rate of turbulence kinetic energy is correctly obtained, the characteristic scales of turbulent flow (i.e. the Kolmogorov and Taylor turbulence micro-scales and the integral scale) are appropriately estimated. The results reveal that the centerline characteristic scales of the plane jet exhibit a linear dependence on the downstream distance (x) at x ≤ 20 h, where h is the height of the nozzle. It is interesting to note that the statistical properties of small-scale turbulence appear to enter their self-preserving state earlier than those of large-scale turbulence in the jet. To our knowledge, this finding has not been reported in the literature.
Elimination of thermal rectification effect and the reversed thermal diode
Authors: Wang Jun  , Li Jing-Ying  , Zheng Zhi-Gang  ,   (1)北京师范大学物理系，北京  100875; (2)阜阳师范学院物理与电子科学学院，阜阳  236041
Published: December 2020

We investigate the important role of interface collisions on the thermal conduction behavior, especially on the thermal rectification effect, of the two-segment lattices. In the high-average temperature regime, it is found that the thermal diode effect may be significantly weaken and even eliminated. Meanwhile in the low-temperature regime, an interesting reversed thermal diode is realized. These behaviors are interpreted in terms of phonon bands mixing induced by interface collisions. The results proposed in this paper reveal that thermal diode effect can be qualitatively influenced if the interface collisions could not be neglected.
Shadow imaging studies on laser-ablated foil target by using an X-ray laser
Authors: Wang Chen  , Zheng Wu-Di  , Fang Zhi-Heng  , Sun Jin-Ren  , Wang Wei  , Xiong Jun  , Fu Si-Zu  , Gu Yuan  , Wang Shi-Ji  , Qiao Xiu-Mei  , Zhang Guo-Ping  ,   (1)Institute of Applied Physics and Computational Mathematics, Beijing 100088, China; (2)Shanghai Institute of Laser Plasma, Shanghai 201800, China
Published: December 2020

There is a "pit" phenomenon in the target surface when long pulse laser ablates the foil target and speeds up the material of target. Laboratorty diagnosis and theoretical simulation of the pit can help us understand the relevant physical processes and check relevant parameters of the procedures. We use 13.9 nm Ni-like Ag X-ray laser as a probe to diagnose the plasma and the pit phenomenon, which is produced by 2ω nanosecond laser irradiation of C8H8 foil target. XRL2D code is used to simulate the experiments. Results show that, when the limiting factor of electron thermal transmittance is 0.03, the simulated pit width and depth (the distance of thin foil accelerated)agree with the results of experiment, but the foil thickening phenomenon in the area far away from the focal spot region cannot be explained the simulation.
Effects of B(N, F) doping on optical properties of TiO2 nanoparticles
Authors: Wu Xue-Wei  , Wu Da-Jian  , Liu Xiao-Jun  ,   Key Laboratory of Modern Acoustics of Ministry of Education, Department of Electronic Science and Engineering, Nanjing University, Nanjing 210093, China
Published: December 2020

The doping effects of the boron (nitrogen, fluorine) are investigated in TiO2 nanoparticles by means of X-ray diffraction (XRD), Raman and UV-Vis absorption spectroscopy. No phase change due to B (N, F)-doping in anatase-TiO2 nanoparticle was found, while significant lattice contraction and enhanced lattice distortion (large c/a-value) were observed in B (N, F)-doped TiO2 nanoparticles, which has been attributed to the occupation of the surface oxygen vacancies by B (N, F) dopants along c-axis of TiO2 crystal lattice. In addition, the absorption band shows evident red-shift for B (N, F)-doped TiO2, which may be related to the increase of lattice distortion (c/a-value) in TiO2 nanoparticles.
Sensitivity analysis and optimization of interatomic potential parameters for perovskites
Authors: Xiao Song-Qing  , Xie Guo-Feng  ,   (1)Faculty of Materials Optoelectronics and Physics, Xiangtan University, Xiangtan 411105, China; (2)Network and Information Administration Center, Xiangtan University, Xiangtan 411105, China
Published: December 2020

An effective interatomic potential is crucial for molecular dynamics simulations. In this paper, a more effective optimization method for potential parameters is proposed. Sensitivity analysis is used to find the key parameters affecting the structure and properties most in all the potential parameters. The secondary parameters are ignored, and the dimension of the optimization is reduced. The genetic algorithm is adopted to optimize the key parameters. The results show that the structure and physical properties of BaTiO3 and SrTiO3 simulated by the optimized potential are more close to experimental data.
Energy calculation of point defects in plutonium by embedded atom method
Authors: Hu Wang-Yu  , Yang Jian-Yu  , Ao Bing-Yun  , Wang Xiao-Lin  , Chen Pi-Heng  , Shi Peng  ,   (1)Department of Applied Physics, Hunan University, Changsha 410082, China; (2)National Key Laboratory for Surface Physics and Chemistry, Mianyang 621907, China
Published: December 2020

Plutonium is vulnerable to aging due to α radioactive decay. The properties and behaviors of point defects in plutonium are the basis for understanding plutonium aging. We have employed a molecular dynamics technique to calculate the formation energy and binding energy of point defects and small helium-vacancy clusters in plutonium, using embedded atom method, Morse pair potential and the Lennard-Jones pair potential for describing the interactions of Pu-Pu, Pu-He and He-He, respectively. A single self-interstitial atom’s steady configuration is 〈100〉 dumb-bell. An interstitial helium atom at octahedral site is more stable than that at tetrahedral site. As a result of high binding energy of an interstitial helium atom to a vacancy, helium atoms can combine with vacancies to form helium-vacancy cluster during the process of self-radiation. The formation energy of helium-vacancy cluster increases with the increasing number of helium atoms. When the number of helium atoms equals to the number of vacancy, the helium-vacancy cluster is rather stable. Both substitutional and interstitial helium atoms are trapped at the grain boundary (GB). The binding energy of the self-interstitial atom at GB core is higher than that of helium atom and vacancy.
An accurate Joule heat model of RLC interconnect based on π equivalent circuit
Authors: Zhu Zhang-Ming  , Zhong Bo  , Yang Yin-Tang  ,   Microelectronics Institute, Xidian University, Xi'an 710071, China
Published: December 2020

With the integrated circuits processing stepping into nanometer scale, the interconnect Joule heat becomes significantly large. Based on the RLC π equivalent circuit, this paper proposes a novel accurate model to evaluate Joule heat power of interconnected line in VLSI. The shielding effect of the inductor and the non-ideal step stimulation are considered in the proposed model. The power consumption of a typical interconnected topology in 90 nm complementary metal-oxide semiconductor process is computed. The error between results of this proposed method and Hspice simulation is within 3% when the input signal’s delay time is within 1 ns. The proposed model can be used to estimate Joule heat consumption where rough heat control is needed, such as route structure in the network on chip.
A kinetic model for silicon film growth by silane/hydrogen glow discharge
Authors: Zhang Hong-Wei  , Chen Gai-Rong  , Zhang Li-Wei  , Lu Jing-Xiao  , Wen Shu-Tang  ,   (1)Key Laboratory of Material Physics of Ministry of Education, Zhengzhou University, Zhengzhou 450052, China; (2)Key Laboratory of Material Physics of Ministry of Education, Zhengzhou University, Zhengzhou 450052, China; Department of Physics, Zhengzhou Teachers College, Zhengzhou 450005, China; (3)School of Chemistry and Chemical Engineering, Xinxiang University, Xinxiang 453003, China; (4)School of Chemistry and Chemical Engineering, Xinxiang University, Xinxiang 453003, China; Key Laboratory
Published: December 2020

During the process of plasma enhanced chemical vapor deposition, the growth rate of microcrystalline silicon films must be improved to reduce manufacture cost. With the increase of growth rate, the photoelectrical properties of such films will be greatly decreased. The main cause is the diffusion length of the precursors on the film surface decreases. In this study, a quantitative kinetic model was developed and the reaction balance equations of SiH3 and H were constructed, and the deposition rate, diffusion length and their influencing factors were obtained. We find that the deposition rate is determined by the fluxes of both SiH3 and H. The diffusion length of precursors is determined by the substrate temperature and the configuration of the surface silicon-hydrogen bonds. The diffusion length has a higher value when the growing film surface is covered by mono-hydrides, it has a smaller value when covered by tri-hydride, and it has a value close to zero when covered by dangling bonds.
Electron structure and electron conductance of fullerene C32 with Au electrodes
Authors: Huo Xin-Xia  , Wang Chang  , Zhang Xiu-Mei  , Wang Li-Guang  ,   (1)School of Science, Heilongjiang August First Land Reclamation University, Daqing 163319, China; (2)School of Science, Jiangnan University, Wuxi 214122, China
Published: December 2020

The first principle based on the density functional theory and nonequilibrium Green's function method is adopted to study the energy level, the electronic structure and the electronic conductance of C32 molecular devices in which Au(1,1,1) electrodes are a ttached to the two farthest carbon atoms when different distances between electrodes and the central molecule are considered. The electronic transmission spectrum and I-V curves of the molecular devices at different distances are obtained. The reasons leading to the electronic structure and the electronic transmission characteristics are analysed. The impacts of the distance between Au electrodes and the central molecule and the gate-voltage on the electronic transmission are discussed. The results show that the distance between the central molecule and Au electrodes has greater influence on the electronic transmission characteristics. The results also show that the C32 molecule has obvious semiconductor characteristics.