bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical simulation and analysis of a high-Q two-dimensional photonic crystal L3 microcavity
Authors: Pan Wei  , Yu He-Jun  , Zhang Xiao-Guang  , Xi Li-Xia  ,   Institute of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876, China
Published: December 2020

A new double-heterostructure photonic crystal L3 microcavity is designed, under the condition of gentle confinement, the quality factor of the cavity is optimized to reach as high as 2.8105 by comparing the simulated mode distribution calculated by finite difference time domain algorithm with the ideal Gaussian distribution, while the mode volume remains small, Veff=0.1813(/n)3. This is the best result at present. Additionally, an energy correlation coefficient is introduced to qualitatively describe the optimization level of a photonic crystal microcavity, which improves the speed and the accuracy of optimization.
Frequency tunable terahertz pulses generated from GaP waveguide emitter
Authors: Liu Feng  , Li Yi  , Shi Jun-Kai  , Hu Xiao-Kun  , Li Jiang  , Li Yan-Feng  , Xing Qi-Rong  , Hu Ming-Lie  , Chai Lu  , Wang Qing-Yue  ,   Ultrafast Laser Laboratory and Center for Terahertz Waves, College of Precision Instrument and Optoelectronics Engineering, Key Laboratory of Opto-Electronics Information Technology (Ministry of Education), Tianjin University, Tianjin 300072, China
Published: December 2020

We report on a frequency-tunable terahertz pulse train generated from a rectangular GaP waveguide emitter pumped by a pulse width tunable femtosecond photonic crystal fiber amplifier. The THz frequency can be tuned by varying the pump pulse duration. The dispersion of the emitter can be controlled via the geometry of the waveguide, and the coherent buildup length can be increased to scale up the output power. Waveguides with different cross sections can be used to tune the THz spectrum. Combined with the pump pulse duration tuning technique, THz pulses with a precisely tunable frequency can be obtained. In the experiment, tunable THz radiation is obtained from a GaP waveguide emitter with a cross section of 1 mm0.7 mm. Finally, a GaP emitter array is designed to achieve a wider tuning range.
Extracting the external-cavity key of a chaotic semiconductor laser with double optical feedback by spectrum analyzer
Authors: Liang Jun-Sheng  , Wu Yuan  , Wang An-Bang  , Wang Yun-Cai  ,   Institute of Optoelectronic Engineering, Dept. of Physics & Optoelectronics, Taiyuan University of Technology, Taiyuan 030024, China
Published: December 2020

Optical-feedback laser diodes have been widely applied in chaotic optical communication, because it can simply generate wideband and high-dimension chaos and its external-cavity length is often regarded as an additional key. In this paper, it is experimentally demonstrated that the time delay signature of a chaotic laser diode with optical feedback can be identificated. Through locally enlarging the power spectral of chaotic light and observing its fine structure, the external-cavity key can be directly extracted by the spectrum analyzer, regardless of the laser diode with single or dual optical feedback of different external cavity length ratio.
TiO2 modified 547 holes microstructured polymer optical fiber preform and basic application on photocatalytic
Authors: Li Dong-Dong  , Wang Li-Li  ,   State Key Laboratory of Transient Optics and Photonics, Xi’an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi'an 710119, China;,   Graduate University of Chinese Academy of Science, Beijing 100039, China
Published: December 2020

In this paper, we report on a novel photocatalytic reactor having 547 pieces of TiO2-nanofilm-modified capillaries, which is derived from a microstructured polymer optical fiber(MPOF) preform. TiO2-film-modified MPOF preform is obtained by directly inhaling P25-doped TiO2 sol into array holes of MPOF and forming TiO2 film on their side walls. The MPOF perform acts as not only a light-transmitting media(rolling-up thin film waveguide, collecting and transmitting light into the TiO2thin film), but also a TiO2supporting and waste-water pipe to supply for photocatalytic degradation of toxic organic solute. Methylene blue(MB) is chosen as a model contaminant in water. The effects of loading quantity of TiO2, pH of MB and initial concentration of MB on photocatalytic degradation are investigated. The photocatalytic reactor has so large surface area for TiO2 loading that photodegradation efficiency is enhanced. As far as we know, the photocatalytic reactor with functions of collecting and transmitting light, conveying matter and loading catalyst has not been reported before.
Study of the proton irradiation damage on Capsule type polarization-maintaining optical fibers made in China
Authors: Zhang Hong-Chen  , Liu Hai  , Qiao Wen-Qiang  , Li Xing-Ji  , He Shi-Yu  , V. V. Abraimof  ,   Space Material and Environment Engineering Laboratory, Harbin Institute of Technology, Harbin 150001, China
Published: December 2020

A spacecraft running in the space environment would be irradiated by the proton, and the irradiation effects on the most important parts of the optical fiber gyroscope in the spacecraft -the optical fiber ring is the most. In order to investigate the irradiation damage induced by proton irradiation on the Capsule type polarization-maintaining optical fibers made in china, the variation of the transportation power at 1310 nm wavelength is measured by means of situ measurement for the 5 MeV and 10 MeV environments protons irradiation on the Capsule type polarization-maintaining optical fibers made in china. The irradiation induced loss is calculated by us. The Stopping and Range of Ions in Matter (SRIM) software was used to simulate the ionic and displacement damage of 5 MeV and 10 MeV energy protons irradiation on the optical fibers. The O 1s and Si 2p analytic spectrum of the before and after irradiation were obtained by means of X ray photoelectron spectroscopy (XPS). Using the Fourier transform infrared spectrometer (FTIR), we analyzed the before and after irradiation spectrum. The results show that at the 1310 nm wavelength, the rradiation induced loss of the of optical fibers increase with the increasing of the protons fluence due to the increase of the SiOH concentration in optical fiber core. The 5 MeV proton irradiation induced loss is worse than that of the 10 MeV mainly because the more worse displacement and the ironic damage induced by 5 MeV proton at the position of the optical fiber core than that of 10 MeV, i.e., the more amount of SiOH generation.
Numerical simulation of a droplet motion in a grooved microchannel
Authors: Zhang Ming-kun  , Chen Shuo  , Shang Zhi  ,   School of Aerospace Engineering and Applied Mechanics, Tongji University, Shanghai 200092, China;,   Science and Technology Facilities Council, Daresbury Laboratory, Warrington WA4 4AD, UK
Published: December 2020

In this paperan improved dissipative particle dynamics(DPD) method was applied to simulate droplet motion in a grooved microchannel. The improved DPD method adopted a recently proposed combination of short-range repulsive and long-range attractive interaction, which can simulate fluid flows with free surfaces, such as droplet motions. The static contact angle between the droplet and the solid wall was simulated with the new potential function, andstatic contactangle～awf/af curve was obtained by Polynomial fit of the 2nd order. The influences ofwall wettability, flow field force, droplet temperature on the flow pattern of droplet in the grooved microchannel were investigated. The results showed that wall wettability and flow field force have large affectson the flow pattern of the droplet, whiledroplet temperature have little affectson it. This article is helpful to understand the fluid flow behavior with free surfaces on rough surfaces.
The irrotational progressive gravity waves propagating on uniform currents in Lagrangian analysis and experiments Part 2. Experimental verification
Authors: Chen Yang-Yih  , Lin Chu-Yu  , Li Meng-Syue  , Lee Cheng-Ta  ,   Department of Marine Environment and Engineering, National Sun Yat-Sen University, Kaohsiung 804, Taiwan, China;,   Department of Hydraulic and Ocean Engineering, National Cheng Kung University, Tainan 701, Taiwan, China
Published: December 2020

The quantitative experiments are made to measure the motional characteristics of water particles in the progressive gravity waves propagating on following and reversing uniform currents. The theoretical results of the third-order Lagrangian solution in Part 1[1] are shown good agreements with those measured by the experiments for the wave-form, the velocity distribution, the mass transport velocity, the particle trajectory, particle's motion period and Lagrangian mean level. It is also verified that identifying parameters of each particle is equal to the coordinates of its position in a still water. Consequentially, the wavelengths of the wave-forms constituted by the particles in the field are all equal to that of the progressive waves and their propagating speeds are the sum of the velocities of the progressive waves and the uniform current as the so-called Doppler effect is proved, but the motion periods and the Lagrangian mean levels of particles are the same as those in the progressive waves. The variations of the orbital forms of particles in the field are also revealed that the orbits like the prolate trochiod, the cycloid and the curtate trochoid are presented in the case of following uniform current as the horizontal velocity components of particles at the section of wave trough are, respectively, negative, zero and positive in the direction of the progressive waves, and that the orbits like the prolate trochoid and the ellipse are occurred in the case of reversing uniform current as the mass transport velocities of particles are, respectively, positive and zero in the direction of the progressive waves, and that the orbits like the turned prolate trochoid, the turned cycloid and the turned curtate trochiod are appeared in the case of reversing uniform current when the mass transport velocities of particles are negative and the horizontal velocity components of particles at the section of wave crest are, respectively, positive, zero and negative in the direction of the progressive waves.
Effect of an asymmetry n-AlGaN layer on performance of dual-blue wavelength light-emitting diodes
Authors: Yan Qi-Rong  , Zhang Yong  , Yan Qi-Ang  , Shi Pei-Pei  , Zheng Shu-Wen  , Niu Qiao-Li  , Li Shu-Ti  , Fan Guang-Han  ,   Institute of Optoelectronic Materials and Technology, South China Normal University, Guangzhou 510631, China
Published: December 2020

The effect of an n-type AlGaN layer on the physical properties of dual-wavelength light-emitting diode (LED) is investigated numerically. The simulation results show that compared with the conventional p-type AlGaN electron-blocking layer (EBL), the n-type AlGaN layer can improve the distribution of electrons and holes more uniformly and realize the radiation balance between electrons and holes in the quantum wells, and further reduce the efficiency dro of dual-blue wavelength LED at high current. In addition, the spontaneous emission rate of two kinds of quantum wells can be adjusted through the control of Al composition. It can be found from the results that the emission spectrum of dual-blue wavelength LED is more stable at low current with an Al composition of 0.16, while the emission spectrum is more stable at high current with an Al composition of 0.12.
Preparation of AlN/C composite foam through annealing recrystallization and its mechanical performance study
Authors: Cheng Sai  , Lü Hui-Min  , Cui Jing-Ya  ,   Department of Applied Physics, Xi'an University of Technology, Xi'an 710048, China
Published: December 2020

Order to get a new type carbon foam material, AlN/C composite foam was successfully synthesized by using AlN as an additive and hollow microspheres/reticulated carbon foam as a basement thought the annealing high-temperature heated process. The prepared samples were characterized by Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM). The results of test indicated that AlN whiskers with diameter of 50nm, length large than 10 um and larger length-diameter ratio were prepared by amorphous AlN recrystallization at the surface of carbon microspheres. Diffraction peaks of XRD demonstrated that the sample was characterized as graphitization and AlN whiskers were hexagonal structure. XPS test showed that there was an obvious peak of CN bond on 287.5 eV, which revealed that AlN and carbon foam through CN bond combined on their interfaces. Meanwhile, it was showed that AlN/C foam material's compression strength was 40.27 MPa through the analysis of the stress-strain of mechanical performance, which increased nearly one order of magnitude compared with the carbon foam material. The results of test showed that compressive strength of carbon foam was obvious reinforced by AlN whisker. And this new composite foam has infinite applications value in various kinds of resist compression and absorbing aeronautical materials.
Electrochemical potential equilibrium of electrons in ideal metallic glasses based on the cluster-resonance model
Authors: Han Guang  , Qiang Jian-Bing  , Wang Qing  , Wang Ying-Min  , Xia Jun-Hai  , Zhu Chun-Lei  , Quan Shi-Guang  , Dong Chuang  ,   Key Laboratory of Materials Modification, Dalian University of Technology, Ministry of Education, Dalian 116024, China;,   College of Physics, Dalian University, Dalian 116622, China
Published: December 2020

Ideal metallic glasses are the metallic glasses that satisfy electronic structure stability. Previously we have developed a so-calledcluster-plus-glue-atom modeland more recently acluster-resonance modelfor the ideal metallic glasses. Good metallic glass forming compositions always satisfy simple cluster formulas [cluster] (glue atoms), with x denoting the number of glue atoms matching one cluster. In this paper we present an electrochemical potential equilibrium criterion based on these models to obtain the number of glue atoms. By examples of Cu-Zr and Co-B bulk metallic glasses, it is confirmed that the experimentally determined good BMG-forming compositions well agree with the calculated composition formulas.
Real time and ex situ spectroscopic ellipsometry analysis microcrystalline silicon thin films growth
Authors: Li Xin-Li  , Gu Jin-Hua  , Gao Hai-Bo  , Chen Yong-Sheng  , Gao Xiao-Yong  , Yang Shi-E  , Lu Jing-Xiao  , Li Rui  , Jiao Yue-Chao  ,   Key Laboratory of Material Physics of Ministry of Education, School of Physical Engineering and Material Physics Laboratory, Zhengzhou University, Zhengzhou 450052, China;,   Henan University of Technology, Zhengzhou 450051, China
Published: December 2020

Microcrystalline silicon thin films with and without a seed layer were deposited using very high frequency plasma enhanced chemical vapor deposition method at a high growth rate. The influence of the seed-layer method on the film growth and structure were investigated using spectroscopic ellipsometry(SE), Raman spectrum and X-ray diffraction. The results show that the seed-layer can not only increase the growth rate, but also promote crystalline nucleation at the initial growth stage. The deposition processes were monitored by real time spectroscopic ellipsometry(RTSE). The film was also measured by ex situ SE in the air. The differences between the RTSE and ex situ SE have been studied in testsing the microcrystalline silicon thin films. Results show that for the thin films the total thickness obtained by RTSE is smaller than that by ex situ SE, while for the thick films the measured total thicknesses by two methods are almost the same. However, the surface roughness thickness detected by RTSE is larger than that by ex situ SE. The reason for this is due to oxidation of the thin film exposed to the air which smoothed the film surface.
Electronic and magnetic properties of SrCoO3:the first principles study
Authors: Wu Hai-Ping  , Chen Dong-Guo  , Huang De-Cai  , Deng Kai-Ming  ,   Department of Applied Physics, Nanjing University of Science and Technology, Nanjing 210094, China
Published: December 2020

Using density functional calculations within the generalized gradient approximation and Hubbard U framework, the electronic and the magnetic properties of SrCoO3 are investigated. The result shows that the spin-up t2g and eg states of Co shift toward the lower energy with the increase of the U value, whereas the spin-down t2g and eg states of Co shift toward the higher energy. The O 2p state almost does not shift with the increase of U value. The electronic structure of SrCoO3 changes from metal state into half-metal state around U of 7-8 eV. The magnetic moment of Co ions increases linearly with U increasing for U 7.0 eV, and almost does not change for U 8.0 eV. Compared with the experimental results, U = 8.0 eV is thought to be suited for the study of SrCoO3. The result shows that with U = 8.0 eV, the magnetic moment on Co site is 3.19 B and SrCoO3 has the half-metallic nature.
First-principles calculation of rutile and anatase TiO2 intrinsic defect
Authors: Peng Li-Ping  , Xia Zheng-Cai  , Yin Jian-Wu  ,   School of Physics, Huazhong University Science and Technology, Wuhan 430074, China;,   School of Physica Science and Technology, Huanggang Normal University, Huanggang 438000, China;,   National High Magnetic Field Center, Huazhong University Science and Technology, Wuhan 430074, China
Published: December 2020

In the paper, we study how the geometry structure and the growing ambience and the Fermi level of several intrinsic point defects effect the defect formation energy of the rutile and anatase TiO2, which type of point defect will be formed, and how to predict the experimental condition of point defect from theory. The key problem is how to calculat the defect formation energy with charge, and correcte the calculation results. The results show the defect type and the defect concentration are related to the nonequilibrium growth condition. In general, under the O-rich condition, VTi will form spontaneously, and under the Ti-rich condition, Ti4+ and VO easily appear in Schottky defects.
Observation of current-induced polarization in (Ga,Mn)As via magneto-optic Kerr measurement
Authors: Gu Xiao-Fang  , Qian Xuan  , Ji Yang  , Chen Lin  , Zhao Jian-Hua  ,   State Key Laboratory for Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
Published: December 2020

Current-induced Kerr rotation spectra and reflectivity spectra of (Ga,Mn)As and p-GaAs were measured in the absence of the magnetic field via magneto-optic Kerr effect around the energy gap. The dependence of the Kerr rotation and the reflectivity on the laser wavelength show Lorentzian profile. The Kerr rotation depends linearly on the current and the reflectivity depends linearly on the square of the current. The Kerr rotation of P-GaAs is much weaker than that of the (Ga,Mn)As which indicate that the doping of Mn enhance the current-induced spin polarization . The dependence of the Kerr rotation and the reflectivity on the temperature was also measured, both showing red shift of their Lorentzian peaks, a familiar behavior as the absorption edge of GaAs. In addition, we observed the dependence of the Kerr signal on the polarizational direction of the incident beam.
Comparison between transmission-mode extended blue GaAs photocathodes in optical structure
Authors: Zhao Jing  , Chang Ben-Kang  , Zhang Yi-Jun  , Zhang Jun-Ju  , Shi Feng  , Cheng Hong-Chang  , Cui Dong-Xu  ,   Institute of Electronic Engineering and Optoelectronic Technology, Nanjing University of Science and Technology, Nanjing 210094, China;,   Science and Technology on Low-Light-Level Night Vision Laboratory, Xi'an 710065, China;,   Xi'an Institute of Applied Optics, Xi'an 710065, China
Published: December 2020

One transmission-mode extended blue GaAs photocathode is prepared by MOCVD , whose integral sensitivity is 1980 A/lm. Its spectral curve is compared with the spectral curve of ITT photocathode for analyzing optical structure. The comparison indicates that the differences lie in the thickness and the Al mole value of the Ga1-xAlxAs window layer, electron diffusion length, and back-interface recombination velocity, which make the photocathode in this experiment inferior to that of ITT in extended blue performance. However our surface electron-escape probability and the thickness of the GaAs active layer are in accordance with those of ITT, which leads their difference in the long waveband part to be less than in the short one. In addition, our absorptivity in the whole response waveband is smaller than that of ITT photocathode, which leads the spectral response and integral sensitivity of the domestic transmission-mode extended blue GaAs photocathode to be inferior to the exotic one.
ExtendedQ-band fluorescence lifetime of Tetraphenyl porphyrins adsorbed on silver nanoparticles
Authors: Yang Zhen-Ling  , Liu Yu-Qiang  , Yang Yan-Qiang  ,   Center for Condensed Matter Science and Technology, Department of Physics, Harbin Institute of Technology, Harbin 150001, China
Published: December 2020

The change ofQ-band fluorescence lifetime of tetraphenyl porphyrins(TPP) adsorbed on the surface of silver nanoparticles is reported. The lifetime was extended when the surface plasmon resonant peak of silver nanoparticles was adjusted to resonant with theQ- absorption band. Silver nanoparticles bring large surface plasmon resonant enhancement effect to the surface light field, and the excited TPP molecules have higher polarity. The enhanced light field will stabilize the TPP molecules of high polarity, which causes the extendedQ-band fluorescence lifetime. It has an important significance in photodynamic therapy using porphyrins as photosensitizer.
The influence of grain boundary on time response of diamond ultraviolet photo-detector
Authors: Wang Lan-Xi  , Chen Xue-Kang  , Wu Gan  , Cao Sheng-Zhu  , Shang Kai-Wen  ,   Science and Technology on Surface Engineering Laboratory, Lanzhou Institute of Physics, Lanzhou 730000, China
Published: December 2020

Persistent photoconductivity(PPC) is a deterring factor for the time response of ultraviolet photo-detectors made of polycrystalline diamond films. The existence of PPC can greatly prolong the response time of photo-detectors. In this paper, ultraviolet photo-detectors with interdigital electrode spacings of 20 μm and 30 μm(denoted as "device A" and "device B", respectively) are fabricated on microcrystalline diamond films, and the influences of grain boundary on time response of diamond ultraviolet photo-detectors are discussed. Results show that performances of PPC and photoconductive gain are present in the two photo-detectors, and the PPC is longer and the photoconductive gain is higher in device B than in device A. It is suggested that grain boundaries may induce a shallow level in the bandgap and act as minority carrier trapping centers, leading to PPC and high gain. There are more grain boundaries between the electrodes in device B than in device A, which hence explains the higher photoconductive gain and responsivity as well as more significant PPC in device B than in device A.
Study of growth, spectra properties and Cr4+ formation mechanism of Cr,Mg:GSGG crystal
Authors: Jiang Da-Peng  , Su Liang-Bi  , Xu Jun  , Tang Hui-Li  , Wu Feng  , Zheng Li-He  , Wang Qing-Guo  , Guo Xin  , Zou Yu-Qi  ,   Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 201800, China;,   Graduate School of Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

Cr,Mg:GSGG crystals are successfully grown by the Czochralski method. The influences of reducing- and oxidizing- annealing treatments on the absorption spectra of Cr,Mg:GSGG crystals are investigated. From the changes of their absorption spectra, it can be inferred that the Cr4+ ions are initially generated at octahedrally coordinated sites, and then exchange positions with tetrahedral Ga3+ ions in neighboring sites under heat exciting. Differences between absorption spectra also suggest that Mg2+ ions can improve the concentration of tetrahedral Cr4+ ions.
Investigation on the power combination of the relativistic magnetrons with axial extraction
Authors: Li Wei  , Liu Yong-Gui  , Yang Jian-Hua  ,   College of Opto-electric Science and Engineering, National University of Defense Technology, Changsha 410073, China
Published: December 2020

The relativistic magnetron with axial extraction, also known as magnetron with diffraction output (MDO), is an important device for the miniaturization and compaetification of magnetron. It is also promising to be one of the most compact narrow band high power microwave sources. Based on the manners and traits of the MDO directly radiating the quasi-TE11 mode in axial direction, the investigation of the power combination of double MDOs with a horn antenna is carried out. After discussing the combination ways and results, a modified configuration is proposed for improving the radiation directivity. Finally, the results show that when the adjacent double MDOs have an open angle of 7 and the common horn antenna has the parameters of h = 600 mm and r = 340 mm, the mode reflection coefficient of the power combination system is 0.31, the maximum gain is 21.5 dB, the radiation mode is TE11.
Pinning chaotic synchronization in complex networks on maximum eigenvalue of low order matrix
Authors: Liang Yi  , Wang Xing-Yuan  ,   Faculty of Electronic Information and Electrical Engineering, Dalian University of Technology, Dalian 116024, China;,   Department of Electronics and Information Engineering, Yili Normal College, Yining 835000, China
Published: December 2020

In this paper, we find the decreasing law of maximum eigenvalue of the principal sub-matrix for coupling matrix, propose a method of calculating quickly pinning nodes in complex networks, and reveal the relation between the pinning strategy and the number pinning nodes. Numerical simulations show the trends of evolution under the conditions of three pinning strategies in a scale-free network and a small world, and the effectiveness of the pinning synchronization by selecting pining nodes randomly in a scale-free network.
A new approach to abrupt change detection based on change of probability density distribution
Authors: Cheng Hai-Ying  , He Wen-Ping  , He Tao  , Wu Qiong  ,   Department of Fundamental Science Teaching, Yancheng Institute of Technology, Yancheng 224051, China;,   National Climate Center, China Meteorological Administration, Beijing 100081, China;,   Jinan Environmental Monitoring Center, Jinan 250014, China;,   National Satellite Meteorological Center, China Meteorological Administration, Beijing 100081, China
Published: December 2020

For a stable dynamic system, probability density distribution (PDD) of a system variable is relatively stable, and if there is a change in dynamic structure of a system, the PDD of the system variable will have some change correspondingly. According to this characteristic of PDD of a dynamic system, in this paper we present two new methods, namely, skewness index and kurtosis index, to detect an abrupt change in a time series by means of identifying some small changes in PDD. Tests on model time series indicate that skewness index and kurtosis index can be used to identify an abrupt change, such as abrupt change in parameter of an equation and abrupt dynamic change. Thus, we provide a new approach to detecting abrupt change in time series based on PDD. Further studies show that the detected results of the skewness index and kurtosis index are almost independence of the length of a subseries.
Design and experiments of a new positive-definite renormalization scheme for advection-diffusion differential equation
Authors: Hao Shi-Feng  , Cui Xiao-Peng  ,   Zhejiang Meteorology Observatory, Hangzhou 310017, China;,   LACS, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
Published: December 2020

Total mass conservation is a basic property of advection-diffusion differential equation. While since the difference schemes is not positive-definite, total mass is not conserved, caused by negative mass in numerical integration. Aiming at this problem, a new positive-definite renormalization scheme is proposed based on the physical meaning of negative mass. Experiments of point-source advection-diffusion show that the new renormalization scheme not only solves the positive-definite problem of advection-diffusion differential equation, but also keeps the property of total mass conservation. Compared with the renormalization scheme in the WRF model, the new positive-definite renormalization scheme has virtues of clear physical meaning and easier mannpulation.
Analysis of an Co-phasing detecting method based on far-field images of sparse-optical-synthetic-aperture system
Authors: Liu Zheng  , Wang Sheng-Qian  , Rao Chang-Hui  ,   College of Opto-Electronics Science and Engineering, National University of Defense Technology, Changsha 410073, China;,   The Key Laboratory on Adaptive Optics, Chinese Academy of Sciences, Chengdu 610209, China;,   The Laboratory on Adaptive Optics, Institute of Optics and Electronics, Chinese Academy of Sciences, Chengdu 610209, China
Published: December 2020

For the sparse-optical-synthetic-aperture telescope system, the co-phasing detection plays an important role for the realization of system's high resolution in solving out piston errors between sub-apertures. In this paper, the relationship between piston error and system's far-field intensity was analyzed based on physical principles, then the impact of piston error on system's far-field images was clarified theoretically. Furthermore, an innovative co-phasing detecting method based on the far-field images' similarity was approved for the bi-sub-aperture systems, with its feasibility, detecting deviation and dynamic range were researched by simulation. The results proved that, with this method, the piston error between the system's two sub-apertures can be soundly detected principally while immune from the problems of 2 ambiguity and direction decision that might exist within some other co-phasing detecting methods. Plus its dynamic range shown from these results, this new co-phasing detecting method provides effective references for deeper research of co-phasing detecting techniques.
Discharging of charged material initiated by impacting of hypervelocity small debris
Authors: Gao Zhu-Xiu  , Li Hong-Wei  , Cai Ming-Hui  , Liu Dan-Qiu  , Huang Jian-Guo  , Han Jian-Wei  ,   Center for Space Science and Applied Research, Chinese Academy of Sciences, Beijing 100190, China
Published: December 2020

It may cause generation of plasma and induce the ESD phenomenon when the super-hypervelocity space small debris impact on the charged spacecraft surface. This is a important factor may cause spacecraft abnormity. In this article, a kind of charged material is impacted on the plasma driven accelerator and the discharging signal induced by impact is collected. The effect of the simulating test is obvious. By theoretical analysis, we verified initiatively the hidden trouble of ESD induced by space debris impacting on the charged materials.
Population transfer of high excited states of Rydberg sodium atoms in a chirped microwave field
Authors: Jiang Li-Juan  , Zhang Xian-Zhou  , Ma Huan-Qiang  , Jia Guang-Rui  , Zhang Yong-Hui  , Xia Li-Hua  ,   Department of Physics, Henan Normal University, Xinxiang 453007, China;,   Department of Physics, Xinxiang University, Xinxiang 453003, China
Published: December 2020

Using the time-dependent multilevel approach (TDMA) and combining the B-spline expansion technique and the model potenial method of atom, the properties of Rydberg sodium atom are investigated. The energy level structure of high excited states and population transfer of sodium atom in a microwave field are studied by numerical calculation, and quantum states are controlled and manipulated by microwave field. The results show that the method we used can be applied to the investigation of the properties of alkali-metal atoms in external field, that the population is very sensitive to the parameters of chirped rate and field amplitude, and that the population can be completely transferred into the target state and trapped there by changing the chirped rate and field amplitude.
Structures and potential energy functions of the ground states of YH,YD,YT molecules
Authors: Xu Yong-Qiang  , Peng Wei-Cheng  , Wu Hua  ,   College of Physics and Electronic Information, Gannan Normal University, Ganzhou 341000, China
Published: December 2020

Using the density functional theory(B3LYP) method, the 6-311++G(3df,2pd), AUG-cc-PVTZ, AUG-cc-PVQZ basis sets for H and effective core potentials for Y, the energies, equilibrium structure and harmonic frequency of the ground states of YH(D,T) molecules are calculated. Based on the theory of atomic and molecular reaction statics, the reasonable dissociation limits of the ground states of YH(D,T) molecules are derived. By comparing the calculation results with the existing experimental and theoretical values, we find that the mixed basis sets LANL2TZ/AUG-cc-PVQZ are most suited for the calculation of the molecules. Consequently, the potential energy surfaces of the ground states of YH(D,T) molecules are scanned at the B3LYP/LANL2TZ/AUG-cc-PVQZ level of theory. The potential energy curves of the ground states of YH(D,T) molecules are obtained by the least square fitting to the Murrell-Sorbie potential energy function. The spectroscopic constants (Be, e, e, ee, De) and force constants ((f2, f3, f4)are calculated and compared with experimental results, indicating that the calculation results are in good agreement with the experimental data.
The theoretical calculation of (e,2e) triple differential cross sections of Ag+ (4p,4d) in coplanar asymmetric geometry
Authors: Zhou Li-Xia  , Yan You-Guo  ,   College of Physics Science and Technology, China University of Petroleum, Dongying 257061, China
Published: December 2020

The three-body distorted-wave Born approximation is used to calculate the (e,2e) triple differential cross sections (TDCSs) of Ag+(4p10) and Ag+(4d10) in different kinematical variables in coplanar asymmetric geometry. The angles 4, 10 and 20 are selected as the scattering electron angles. We find that the position of binary peak or the dip between split peaks are not in the direction of momentum transfer, which is probably ascribed to one kind of double-binary collision. We also find that the binary peaks show abnormal splits for Ag+(4p10). Such abnormal splits indicate that an (e,2e) process for inner valence orbital of ionic target becomes more complicated than for outer valence orbital. Furthermore, beside the binary peak and the recoil peak, some pronounced peaks appear at certain ejected angles in the (e,2e) TDCSs of Ag+(4p10) and Ag+(4d10). We consider that these pronounced peaks are probably related to one kind of double-binary collision.
Cross sections for the electron impact non-dissociative ion of hydrogen and its isotopic molecule
Authors: He Man-Li  , Wang Xiao  , Gao Si-Feng  ,   PLA University of Science and Technology, Nanjing 210007, China
Published: December 2020

In the edge plasma, hydrogen and its isotopic molecule will be ionized via collisions with the energetic electrons in the plasmas. The cross section data for the electron impact non-dissociative ion of the hydrogen and its isotopic molecule, which are unavailable from the literature are calculated on the basis of Morse potential function, Franck-Condon theory and semi-classical Gryzinski method. The change of cross section with electron energy and the effect of vibrational level of ground state on the cross section are presented in the paper. The results show that the vibrational excitation plays an important role in the process of ion.
Numerical simulation and experimental study of thermal-induced-depolarization in 2 m Cr,Tm,Ho:YAG laser
Authors: Li Zhe  , Jiang Hai-He  , Wang Li  , Yang Jing-Wei  , Wu Xian-You  ,   Anhui institute of optics and fine mechanics, Chinese Academy of Sciences, Hefei 230031, China
Published: December 2020

The theory of thermal-induced-depolarization is analyzed, the distribution of depolarization is numerically simulated, and the result is verified by the polarized light interferometry. The experimental result is coincident with the numerical simulation, which shows that the distribution of depolarization in the cross section of Cr,Tm,Ho:YAG is crisscross, and increases with the pump energy increasing. The direction of the worst depolarization is 45 with respect to the polarization direction of the polarizer. According to the numerical simulation, we employ a /4-plate to compensate the depolarization of a high-energy Cr,Tm,Ho:YAG laser. The pulse energy increases by 24% after compensation.
One-dimensional simulation of dielectric barrier glow discharge in atmospheric pressure Ar
Authors: Zhang Zeng-Hui  , Shao Xian-Jun  , Zhang Guan-Jun  , Li Ya-Xi  , Peng Zhao-Yu  ,   State Key Lab of Electrical Insulation and Power Equipment, School of Electrical Engineering, Xi’an Jiaotong University, Xi’an 710049, China
Published: December 2020

In order to investigate the mechanism of dielectric barrier atmospheric pressure glow discharge(APGD) in Ar, an one-dimensional multiple particle self-consistent coupled fluid model is proposed. And the finite-element method (FEM) is used in the numerical calculation model, so the periodic evolvement waveforms of gas voltage, barrier surface charge density and discharge current density are investigated. The spatio temporal distributions of electrons, ions, metastable particles density and space electrical field are also obtained. The simulation results show that the charges accumulated on the barrier dielectric surface play an important role in ignition and extinguishment of the discharge. With the increase of applied voltage amplitude, the DBD breakdown occurs ahead of time, and discharge current density and the surface charge density increase gradually, which indicate that the discharge process becomes fierce. Furthermore, with the increase of relative permittivity of dielectric material, the discharge current density also gradually increases. The spatio temporal distributions of the particles density and the space electrical field show that the DBD breakdown occurs every half the AC period and the discharge under conditions considered in this model is a typical atmospheric pressure glow discharge(APGD), having an obvious cathode fall region, a negative glow region, and a positive column region.
Electronic theory of the mechanism of corrosion of Pb-Mg-Al alloy
Authors: Duan Yong-Hua  , Sun Yong  , He Jian-Hong  , Peng Ming-Jun  , Guo Zhong-Zheng  ,   Faculty of Material Science and Technology, Kunming University of Science and Technology, Kunming 650093, China;,   Key Lab of Advanced Materials of Yunnan Province, Kunming University of Science and Technology, Kunming 650093, China
Published: December 2020

The cohesive energies, Fermi energies and local density of states (LDOS) are calculated by the first-principles based on pseudopotential plane wave method in this paper to investigate the physical nature of corrosion of Pb-Mg-Al alloy. The mechanism of electrochemical corrosion is analyzed according to the calculated electronic structure parameters. The results show that the stable phase in Pb-Mg-Al alloy is Mg17Al12>Mg2Pb>Mg. The Fermi energy (Ef) values of these phases with Ef(Mg)>Ef(Mg2Pb)>Ef (Mg17Al12) indicate that Mg is most likely to lose electrons while Mg17Al12 is difficult. LDOS result reveals that Mg and Mg2Pb phases are unstable compared with Mg17Al12 in the same external conditions, they are more likely to lose electrons and easier to corrod. The difference in Fermi energy between different phases in Pb-Mg-Al alloy forms the electrodynamic force of the electrochemical corrosion, which leads electrons to flow from the Mg and Mg2Pb phases with higher Fermi energy to Mg17Al12 phase with lower Fermi energy, further to corrode in Pb-Mg-Al alloy.
Defining nearest neighbor clusters in alloy phases using radial distribution of atomic density
Authors: Chen Ji-Xiang  , Qiang Jian-Bing  , Wang Qing  , Dong Chuang  ,   Key Laboratory for Materials Modification by Laser, Ion and Electron Beams (Dalian University of Technology), Ministry of Education, Dalian 116024, China;,   Department of Physics, Dalian Maritime University, Dalian 116026, China
Published: December 2020

Metallic glasses, quasicrystals and many intermetallic compounds belong to complex alloy phases which are characterized by specific nearest-neighbor coordination polyhedral clusters representing the local atomic features of their parent phases. However, the nearest neighbor atoms are often distributed on multiple shells, which makes the cluster difficult to define exactly. For an alloy phase dominated by the clusters, there showed appear distinct differences between the cluster part and the average structure of the phase, especially with regards to the atomic density. The clusters should have the highest atomic density so that their presence is very pronounced in phase compared with the average structure. In this paper, radial distribution of atomic density (numbers of atoms contained in different spherical shells) is proposed to define the cluster in a clear manner. The spherical shell enclosing the highest atomic density and having dense-packed triangular facets is selected as the nearest-neighbor cluster. Al-Ni-Zr alloy phases are taken for example to illustrate the easy use of this method, and the relationship between cluster and metallic glass formation is also explained.
Stability of hydrogen in tungsten with carbon impurity: a first-principles study
Authors: Jin Shuo  , Sun Lu  ,   School of Physics and Nuclear Energy Engineering, Beihang University, Beijing 100191, China
Published: December 2020

Stability of hydrogen (H) in tungsten (W) with carbon (C) impurity is investigated by using the first-principles method. In intrinsic W, C exhibits a week attractive interaction with H at a distance of ～2.5Å, and it is the most stable site of H in the bulk W with C. In the presence of the monovacancy in W, H prefers to bind onto an isosurface of the same charge density of 0.10 Å-3, due to the existence of C. Our research finds that the monovacancy in W can contain only ten H atoms and H molecule cannot be formed in comparison with the result without C, suggesting a strong effect of C on H stability in W. When two C atoms exit in the vacancy, the charge density of the isosurface that H binds onto is 0.13 Å-3.
A analytic model for the threshold-voltage of novel high-speed semiconductor device IMOS
Authors: Li Yu-Chen  , Zhang He-Ming  , Zhang Yu-Ming  , Hu Hui-Yong  , Xu Xiao-Bo  , Qin Shan-Shan  , Wang Guan-Yu  ,   Key Laboratory for Wide Band-Gap Semiconductor Materials and Devices, School of Microelectronics, Xidian University, Xi’an 710071, China
Published: December 2020

A threshold voltage model is created by analyzing differents distributions of surface electric field and the condition of avalanche breakdown, based on the structure of a novel high speed semiconductor device p-IMOS in this paper. Model verification is carried out using the 2D device simulator ISE. By analyzing the model, the dependences of threshold voltage on drain-source voltage, Si layer thickness and gate length are studied. The results of the model are in good agreement with experimental results and ISE simulation results. The proposed model can also be easily used for the reasonable analysis and the design of p-IMOS.
Photoinduced change in resistance of charge-ordering Gd0.55Sr0.45MnO3 thin film
Authors: Zhao Sheng-Gui  , Jin Ke-Xin  , Luo Bing-Cheng  , Wang Jian-Yuan  , Chen Chang-Le  ,   School of Science, Xi’an University of Science and Technology, Xi’an 710054, China;,   Shannxi Key Laboratory of Condensed Matter Structural and Properties, Northwestern Polytechnical University, Xian 710072, China
Published: December 2020

The compound and the film of the critical charge-ordering Gd0.55Sr0.45MnO3 thin film are prepared using the solid state reaction technique and the pulsed laser deposition method respectively. The properties of the photoinduced relative change in the resistance of the film are investigated. Experimental results indicate that the film exhibits the semiconductive conduction and the charge-ordering temperature is about 70 K from the fitting of a variable-range hopping model. The maximum value of the photoinduced relative change in resistance is about 99.8% when the laser with a power density of 40 mW/mm2 irradiates the film, and the rise time is about 8s independent of temperature. The maximum value of the photoinduced relative change in resistance is about 44% at T=20 K when the laser with a power density of 6 mW/mm2 irradiates the film. The time constant is increased with the increase of temperature, which is attributed to the competition between photoinduced effect and thermal fluctuation.
Finding vital node by node importance evaluation matrix in complex networks
Authors: Zhou Xuan  , Zhang Feng-Ming  , Li Ke-Wu  , Hui Xiao-Bin  , Wu Hu-Sheng  ,   Engineering College, Air Force Engineering University, Xi'an 710038, China
Published: December 2020

In order to evaluate the node importance in complex network, considering the disadvantages of node deletion method, node contraction method and betweenness method, through defining the node efficiency and the node importance evaluation matrix, a method to find the vital node in complex networks is proposed by using the node importance evaluation matrix. Considered in this method are the node efficiency, node degree and adjacent node importance contributions, and used adjacent node degree and efficiency value to characterize the contribution of their importance. Finally, an optimized algorithm whose time complexity was O(Rn2) is provided. Experiments show that this method is effective and feasible, and it is applicable to large scale complex networks.
Analysis of statistical fluctuation in decoy state quantum key distribution system
Authors: Jiao Rong-Zhen  , Tang Shao-Jie  , Zhang Chao  ,   Science School, Beijing University of Post and Telecommunication, Beijing 100876, China
Published: December 2020

Decoy state has proven to be a very useful method of significantly enhancing the performance of a quantum key distribution (QKD) system with practical light sources. The data-set size in practical QKD protocol is always finite, which will cause statistical fluctuations. The gain and the error rate of the quantum state are analyzed by considering absolutely statistical fluctuation. The relation between key generation rate and the secure communication distance is shown with exchanged quantum signal (N = 106 -1012) by the method of two-decoy-state protocol under the condition that communication wavelength is 1310 nm (or1550 nm). The result indicates that the minimal number of exchanged quantum signals increases obviously with the increase of transmission distance. The secure transmission distance is 135 km under the condition that quantum signal is 1012.
Weak characteristic signal detection based on scale transformation of Duffing oscillator
Authors: Lai Zhi-Hui  , Leng Yong-Gang  , Sun Jian-Qiao  , Fan Sheng-Bo  ,   School of Mechanical Engineering, Tianjin University, Tianjin 200072, China
Published: December 2020

The chaos detection method based on Holmes Duffing equation is studied. Since this method is suitable only for the detection of a single signal frequency, the selection of the equation parameters is inconvenient, and the noise may affect the detection results, we propose a new method of detecting weak characteristic signals based on the scale transformation of Duffing oscillator. The numerical simulation shows that the proposed method can be used to detect harmonic signal with any frequency and phase by only a set of determined parameters.