bluuebunny/crossref_metadata_2025 huggingface dataset:
Evolution of nonlinear seismic waves in microstructured earth crust
Authors: Han Hai-Ying  , Naranmandula  , Shuang Shan  ,   College of Physics and Electronics, Inner Mongolia University for Nationalities, Tongliao 028043, China
Published: December 2020

Study of propagation and evolution of nonlinear seismic wave in earth crust is of important practical significance. In this paper, evolutions of nonlinear seismic longitudinal wave and transverse wave in microstructured earth crust are simulated detailedly by using the finite difference method. The results indicate that nonlinear seismic longitudinal wave and transverse wave in microstructured earth crust may evolve into one solitary wave or two solitary waves or solitary wave train, or disappearance. The initial amplitude of seismic wave, dispersion coefficient and body force factor significantly influence the evolution process. Our results reveal the evolution law of nonlinear seismic wave in a microstructured earth crust, which will help to explain some special seismic wave phenomena in theory.
New parameterization of wave-current interaction used in a two-way coupled model under typhoon conditions
Authors: Liu Lei  , Fei Jian-Fang  , Zhang Li-Biao  , Huang Xiao-Gang  , Cheng Xiao-Ping  ,   Institute of Meteorology, PLA University of Science and Technology, Nanjing 211101, China
Published: December 2020

The two important upper ocean physical processes, i.e., radiation stress and wave-induced mixing effects, have not been simultaneously taken into consideration in the wave-current coupled parallel run models. Under the current formulations, neither the effect of stratification nor the error during computation is fully suggested. A new simplified parameterization scheme combining wave radiation stress with wave-induced mixing is introduced into a coupled model which consists of wave (WAVEWATCH Ⅲ) and current (POM) model, and typhoon KAEMI (2006) is taken as the example to carry out four sets of experiments. The numerical experiments show that the turbulence enhanced by the wave-induced mixing in mixing layer transfers momentum and heat into down water layers, but in general, does not regularly change surface currents. The wave radiation stress transfers momentum horizontally, and thus it changes horizontal currents regularly. When both physical processes are included in this coupled model, two effects are superposed in the simulation. As an important dynamic factor, the current affects the significant wave height and its distribution, which transfers horizontal momentum and makes significant wave height much higher in the present study. Furthermore, the current vector rotates clockwise at the time of the 48th hour due to the inertial oscillation probably being the signal of wave-current interaction amplified by the typhoon approaching.
Quantum properties of two-level atoms interacting with nonlinear coherent states
Authors: Yu Wen-Jian  , Wang Ji-Suo  , Liang Bao-Long  ,   School of Physics Science and Information Technology, Liaocheng University, Liaocheng 252059, China;,   School of Physics and Engineering, Qufu Normal University, Qufu 273165, China
Published: December 2020

Using the numerical method, we study the collapse and the recovery of atom, the anti-bunching and the amplitude-squared squeezing of two-level atoms interacting with nonlinear coherent field. The variations of the quantum properties with the parameter of light field, the initial state of the atom and the Lamb-Dicke parameter of the nonlinear coherent state are discussed.
Random number generator based on discrete trajectory transform in generalized information domain
Authors: Zhang Guo-Ji  , Li Xuan  , Liu Qing  , Zhang Xia-Yan  ,   Department of Science, South China University of Technology, Guangzhou 510640, China;,   Department of Computer Science and Engineering, South China University of Technology, Guangzhou 510640, China
Published: December 2020

Generalized information domain is the space of all digital information that can be expressed by binary code. In this paper, a random number generator based on discrete trajectory transform in generalized information domain is proposed. The generator exploits generalized information domain as the space of entropy source, and uses the digital information selected by the user as the output of entropy source, and then utilizes the discrete trajectory transform method to generate random number based on the reconstruction of the output of entropy source. The proposed generator shows good characteristics of balance, period and anti-collision, and it demonstrates satisfactory randomness through the National Institute of Standards and Technology test. This generator can be utilized to generate high secure random number quickly and conveniently.
Oscillations and non-smooth bifurcations in a generalized BVP circuit system
Authors: Li Shao-Long  , Zhang Zheng-Di  , Wu Tian-Yi  , Bi Qin-Sheng  ,   Faculty of Science, Jiangsu University, Zhenjiang 212013, China;,   General Department, ZhenJiang Watercraft College, Zhenjiang 212013, China
Published: December 2020

The complicated dynamical evolution of a generalized BVP circuit system with piecewise linear characteristics is explored. The phase space is divided into different types of regions by the nonsmooth boundaries. In each region, the stabilities of the equilibrium points are investigated, from which the critical conditions related to simple bifurcations as well as Hopf bifurcations are obtained. By employing the analysis of the distribution of the eigenvalues of the generalized Jacobian matrix, the bifurcation behaviors related to the nonsmooth boundaries are explored in detail. It is pointed out that when pure imaginary eigenvalues associated with the generalized Jacobian matrix appear, the Hopf bifurcation may take place, leading the system to change from periodic motion into the quasi-periodic oscillation, while when zero eigenvalue occurs, it may lead the system to oscillate between different equilibrium points. Combined with the numerical simulations, two typical oscillation behaviors of the system verify the theoretical results.
Molecular dynamics simulation for the effect of hydrogen on the water of pressurized water reactors
Authors: Liu Hua-Min  , Fan Yong-Sheng  , Tian Shi-Hai  , Zhou Wei  , Chen Xu  ,   Sichuan University, Institute of Nuclear Science and Technology, Key Laboratory of Radiation Physics and Technology, Ministry of Education, Chengdu 610064, China;,   Mianyang Normal University, College of Mathematics and Computer Science, Mianyang 621000, China
Published: December 2020

In this paper, molecular dynamics is used to simulate dynamic properties and micro-structure of the water-hydrogen particle system under various conditions: 1 atm, 293 K; pressurized water reactor (PWR) environment of 155 atm, 626 K; the number of water molecules of 256, numbers of hydrogen (H2) molecules of 0, 25, 50, 75 and 100, and the mean square displacement (MSD) in the particle system increases with the number of particles of the hydrogen increasing. Under the PWR environment, with hydrogen molecule number being 75, the MSD is about 6 times higher than that in chamber ambient. At the same time, under such a condition, the MSD of particle system increases 131.8829% higher than that in the case of the number being 0. In addition, the micro-structure of particle systems, from the view of the radial distribution functions (RDF), increase with the increase of concentration of hydrogen in chamber ambient, which coincides with the fact that the hydrogen dissolution in water increases the particle density around oxygen ions at nomal temperature and normal pressure. While in the PWR environment, the radial distributions of the water with the numbers of hydrogen molecules of 75, 50, 25 and 0 have no big change, but the radial distribution with the number of hydrogen molecules of 100 increases significantly and it is 22.0048% higher than that in the case of the number being 0. It can be seen from simulation data that hydrogen added to PWR significantly inhibits the oxygen dissolution in water. This phenomenon and its cause are revealed comprehensively in this paper.
Redistribution of solid-deuterium induced by infrared irradation
Authors: Bi Peng  , Lei Hai-Le  , Liu Yuan-Qiong  , Li Jun  , Yang Xiang-Dong  ,   Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, China;,   Research Centre of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

In this paper, the internal mechanism of solid deuterium spatial distribution induced by infrared radiation is studied. The changes in spatial distribution and micro-structure of solid deuterium are also discussed as the results of wavelength and heating time of IR light. It is found that the micro-structure of solid deuterium which is irradiated by a special IR light is changed from polycrystal to monocrystal, the solid deuterium is redistributed and becomes more uniform and transparent. The best wavelength of IR light for heating solid deuterium is 3140 nm. When the output power of 3140 nm IR light is 100 upW, the redistribution time of solid deuterium is about 18 min.
Ge-vacancy complexes in Ge-doped czochralski silicon crystal
Authors: Wu Tai-Quan  ,   Department of Physics, China Jiliang Universtiy, Hangzhou 310018, China
Published: December 2020

The first-principls theory is used to study the interaction between the Ge atom and the vacancies in Ge-doped czochralski silicon. The CASTEP calculation shows the stable structural model of Ge atom and one vacancy, two vacancies and three vacancies through the distance between the Ge atom and vacancy (or the vacancy centers) and the size of the area (or volume). The calculation shows that the Ge atom introduced into the GCZ Si crystal tends to accumulate with the vacancy and then seeds for the Ge-vacancy complexes.
First-principles study on the sensitization of small molecule adsorbed on ZnO nanowire
Authors: Wang Le  , Liu Yang  , Xu Guo-Tang  , Li Xiao-Yan  , Dong Qian-Min  , Huang Jie  , Liang Pei  ,   College of Optics and Electronic Science and Technology, China Jiliang University, Hangzhou 310018, China
Published: December 2020

The electronic properties of the ZNWs (ZnO nanowire) as one of important part of novel SC (solar cells) are very important, which can greatly affect the performance of the SC. Based on the density function theory combined with the plane-wave ultra soft pseudo-potential method, the structures, the adsorption energies and the electronic structures of the C2H6O (ethanol), C6H5FS (4-fluoro-benzenethiol), C7HF7FS (2, 3, 5, 6- tetrafluoro-4-(trifluoromethyl) benzenethiol) clusters adsorbed (0001) hexangular ZNWs are calculated. Firstly, the most stable configuration is found out from different adsorbed ones based on the principle of lowest energy by calculating their total energy. The results also indicate that C7HF7FS adsorption is energetically favorable. Then, the densities of state and the electronic structures of different adsorbed systems are calculated. Furthermore, the mechanism for adjusting the band-gap of the absorbed system is investigated and the results indicate that the chemical modification of ZNWs with the small molecule groups results in little change in the electronic property of the system. Meanwhile, charge transfer takes place to a certain extent between the C7H7FS and C6H5FS.
Theoretical investigation on molecular constants of PH, PD and PT molecules
Authors: Wang Jie-Min  , Sun Jin-Feng  , Shi De-Heng  , Zhu Zun-Lue  , Li Wen-Tao  ,   College of Physics and Electronic Information, Luoyang Normal College, Luoyang 471022, China;,   College of Physics and Information Engineering, Henan Normal University, Xinxiang 453007, China
Published: December 2020

The potential energy curves (PECs) of the PH (X3-, a1 and A3) are investigated by the highly accurate valence internally contracted multireference configuration interaction (MRCI) method and the MRCI method including the Davidson modification (+Q) in combination with the correlation-consistent basis sets, aug-cc-pV5Z. With these PECs obtained here, the spectroscopic parameters of three isotopologues, PH (X3-, a1 and A3), PD (X3-, a1 and A3) and PT (X3-, a1 and A3), are determined. These parameters are compared in detail with those previously reported in the literature, and agreement is found between the present results and the experimental data. The values of vibrational level G(), inertial rotation constant B and centrifugal distortion constant B for the first 12 vibrational levels of PH (X3 -), PD (X3 -) and PT (X3 -), are calculated when the rotational quantum number J equals zero, which are in agreement with the available measurements. Comparison with the available experimental data shows that the present molecular constants are accurate.
Photo-detachment of hydrogen negative ion in a magnetic field near a dielectric surface
Authors: Tang Tian-Tian  , Wang De-Hua  , Huang Kai-Yun  , Wang Shan-Shan  ,   College of Physics, Ludong University, Yantai 264025, China
Published: December 2020

Using the closed orbit theory, we study the photo-detachment of H- in a magnetic field near a dielectric surface. The photo-detachment cross section of this system is also derived and calculated. It is found that the photo-detachment cross section is not only related to the magnetic field strength, but also depends on the dielectric constant. For a given ion-surface distance and dielectric constant, with the increase of the magnetic field strength, the number of the closed orbits increases greatly and the oscillatory structure in the photo-detachment cross section becomes much more complicated. On the other hand, for a given magnetic field strength, the dielectric constant also has a great influence on the photo-detachment process of negative ion. Above the ionization threshold, the photo-detachment cross section becomes oscillatory. With the increase of the dielectric constant, the oscillatory structure in the cross-section becomes much more complicated. Therefore we can control the photo-detachment of negative ion by changing the magnetic field strength and the dielectric constant. This study provides a new understanding of the photo-detachment process of negative ion in the presence of external fields and surfaces.
Experiment study of ionization limit shift of europium atoms in electric fields
Authors: Shen Li  , Ye Shi-Wei  , Dai Chang-Jian  ,   School of Science, Tianjin University of Technology, Tianjin 300384, China
Published: December 2020

In this paper, we present a new method to determine the first ionization limit of europium atom. Firstly, time delayed field ionization is used to detect highly excited Rydberg states of europium atom. Secondly, reversed static electric field is used to exclude ion signal from photoionization, autoionization and other path. The law of first ionization limit shift of europium atom in electric field is studied. First ionization limit in zero electric field is deduced from data of first ionization limit shift in electric field. This value is well coincident with the reported values deduced by other methods.
Realization of microwave wave signal time reversal based on time lens theory
Authors: Ding Shuai  , Wang Bing-Zhong  , Ge Guang-Ding  , Wang Duo  , Zhao De-Shuang  ,   Institute of Applied Physics, University of Electronic Science and Technology of China, Chengdu 610054, China
Published: December 2020

Time reversal electromagnetics is a new branch of science. The critical factor for the practical implementation of time reversal technique is to obtain time reversed signal efficiently. In this paper, based on the principle of time lens, a method of obtaining time-reversed microwave signal is studied. First, according to the principle of time lens, conditions for realizing time-reversed waveform are derived. The process for obtaining time reversed signals is simulated numerically. Then two chirp electromagnetic bang gap (CEBG) structures are fabricated to construct dispersion channels. And a time reversed signal on a 1.5 ns time scale is obtained in experiment. Due to the difference between CEBG and ideal dispersion channel, there exists a distortion in the experiment results, for whitch the reasons are analyzed.
Experimental study on detection of the high signal-to-noise ratio of the carrier-envelope offset frequency in an Er-doped fiber femtosecond laser
Authors: Cao Shi-Ying  , Meng Fei  , Fang Zhan-Jun  , Li Tian-Chu  ,   Division of Metrology in Time and Frequency, National Institute of Metrology, Beijing 100013, China
Published: December 2020

The key techniques for the realization of the femtosecond optical frequency comb are the detection of the carrier-envelop-offset frequency (f0) and the improvement of the signal to noise ratio (S/N) of f0. The influence of the length and the vibration of the fiber between the oscillator and the amplifier, and the pump power of the amplifier on the S/N of the f0 is experimentally studied. With optimized parameters, a f0 with 40 dB S/N is obtained in the Er-doped fiber femtosecond laser.
Temperature dependence of elastic modulus of single crystal sapphire investigated by laser ultrasonic
Authors: Song Yun-Fei  , Yu Guo-Yang  , Yin He-Dong  , Zhang Ming-Fu  , Liu Yu-Qiang  , Yang Yan-Qiang  ,   Center for Condensed Matter Science and Technology, Department of Physics, Harbin Institute of Technology, Harbin 150001, China;,   Center of Composite Materials, Harbin Institute of Technology, Harbin 150001, China
Published: December 2020

The longitudinal ultrasonic wave launched by ns-laser pulse is used to measure the temperature dependence of the elastic modulus C33 of single crystal sapphire. The result shows that in a temperature from room temperature to 1000 ℃ the elastic modulus of sapphire C33 reduces as the temperature increases, following the relationship C33 = - 1.541 10-5T2 - 0.021T + 498.3. In this method, the ablation mechanism is adopted to launch strong longitudinal waves, therefore, the result is accurate that the error of the measurement is estimated to be no more than 0.1%.
Line width compression and temporal coherence of stimulated Brillouin scattering
Authors: Zhang Dong  , Zhang Lei  , Shi Jiu-Lin  , ShiJin-Wei  , Gong Wen-Ping  , Liu Da-He  ,   Key Laboratory of Nondestructive Test (Ministry of Education), Nanchang Hangkong University, Nanchang 330063,China;,   Applied Optics Beijing Area Major Laboratory,Department of Physics, Beijing Normal University, Beijing 100875, China
Published: December 2020

The effect of line width compression of stimulated Brillouin scattering (SBS) is investigated experimentally. It is found that the line width compression is directly related to the compression of pulse duration. A new method of measuring the line width of SBS through measuring the pulse duration is proposed. The temporal coherence of SBS is also investigated. It is revealed that the temporal coherence of SBS varies with the compression ratio of pulse duration. High pulse duration compression and good temporal coherence cannot be obtained simultaneously.
Separate holographic-Hamiltonian screening soliton pairs in a biased series photorefractive crystal circuit
Authors: Wang Sheng-Lie  , Cai Xin  , Liu Jin-Song  ,   Wuhan National Laboratory for Optoelectronics, School of Optoelectronic Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China;,   School of Science, Wuhan University of Technology, Wuhan 430070, China
Published: December 2020

Separate holographic-Hamiltonian screening soliton pairs are predicted in a biased series photorefractive crystal circuit consisting of two photorefractive crystals connected electronically by electrode leads in a chain with a voltage source. The existence of four types of the separate soliton pairs:dark-dark, bright-dark, dark-bright and bright-bright, in such a circuit is proved. Under the limit that the spatial extent of the optical wave is much less than the width of the crystal, the Hamiltonian dark soliton can affect the other soliton by the light-induced current whereas the Hamiltonian bright soliton and holographic soliton cannot affect the other soliton in the soliton pair.
Linear electro-optic effect of ultrashort laser pulses in LiNbO3 crystal and its dispersion compensation
Authors: Zhong Dong-Zhou  , She Wei-Long  ,   State Key Laboratory of Optoelectronic Materials and Technologies,Sun Yat-sen University, Guangzhou 510275, China;,   School of Information Engineering, Wuyi University,Jiangmen 529020, China
Published: December 2020

For the linear electro-optic (EO) effect of ultrashort laser pulses in LiNbO3crystal, we investigate in this paper the compensation of the group-velocity dispersion, as well as the first- and second-order refractive dispersion by means of optical phase conjugation (OPC). It is found that for arbitrary input pulse durations, these dispersions can be compensated. And the waveforms of output pulses are almost the same as those of input ones. Also, the durations of output pulses can be compressed further when the phases of output pulses of OPC are modulated by EO effect in another LiNbO3for dispersion compensation. And the narrower the input duration, the more evident the compression of output duration becomes.
Noether symmetry and Noether conserved quantity of Nielsen equation in a dynamical system of the relative motion with nonholonomic constraint of Chetaev's type
Authors: Wang Xiao-Xiao  , Sun Xian-Ting  , Zhang Mei-Ling  , Xie Yin-Li  , Jia Li-Qun  ,   School of Science, Jiangnan University, Wuxi 214122, China;,   School of Electric and Information Engineering, Pingdingshan University, Pingdingshan 467002, China
Published: December 2020

Noether symmetry and Noether conserved quantity of Nielsen equation in a dynamical system of the relative motion with nonholonomic constraint of Chetaev's type are studied. The differential equation of motion of Nielsen equation for the system, the definition and the criterion of Noether symmetry, and the expression of Noether conserved quantity deduced directly from Noether symmetry for the system are obtained. An example is given to illustrate the application of the results.
Dispersion and birefringence analysis of photonic crystal fiber with rhombus air-core structure
Authors: Wang Wei  , Yang Bo  ,   College of Automation, Harbin Engineering University, Harbin 150001, China
Published: December 2020

Aiming at the requirements for multi-zero dispersion points and high birefringence of photonic crystal fibers, a new kind of photonic crystal fiber with rhombus air-core structure is composed of four air holes locate at four points of rhombus is proposed. By using the numerical analysis method based on the finite element, we simulate the dispersion and the birefringence characteristics of photonic crystal fiber, and obtain the relationships between dispersion and wavelength, dispersion and size of structure, birefringence and wavelength, birefringence and size of structure. Simulation results show that better birefringence can be obtained when the requirement of power is met. In addition, two zero dispersion points can be obtained when diameter d1 is 0.4 m or 0.6 m. The results are of significance for the further development of photonic crystal fiber with multi-zero dispersion points.
Cooling efficiency investigation of forward-facing cavity and opposing jet combinatorial thermal protection system
Authors: Lu Hai-Bo  , Liu Wei-Qiang  ,   College of Aerospace and Material Engineering, National University of Defense Technology, Changsha 410073, China
Published: December 2020

The cooling efficiency of a forward-facing cavity and opposing jet combinatorial thermal protection system is investigated, by which the flow field parameters, the aerodynamic force, and the surface heat flux distribution are obtained. The numerical simulation method is validated by experiment with no opposing jet model. The analysis of the numerical simulation results shows that this kind of combinatorial thermal protection system has an excellent effect on cooling the outer body surface of the nose-tip. By introducing an opposing jet with a small total pressure (total pressure ratio PR is 0.1), the cooling effect of combinatorial configuration can be much better than that of a single cavity. With the opposing jet speed increasing, the cooling efficiency is improved and the aerodynamic resistance is reduced. The combinatorial system is suited for the thermal protection of hypersonic aircraft that needs a long-distance and long-time flight.
First-principles study of the electronic structure and optical properties of GaN(0001) surface
Authors: Du Yu-Jie  , Chang Ben-Kang  , Zhang Jun-Ju  , Li Biao  , Wang Xiao-Hui  ,   Department of Physics, Institute of Bingzhou, Bingzhou 256603, China;,   Institute of Electronic Engineering and Opto-electric Technology, Nanjing University of Science and Technology, Nanjing 210094, China
Published: December 2020

The band structure, the density of states, the surface energy, the work function, and the optical properties of GaN(0001)(22) clean surface are calculated systematically by the first-principles plane-wave ultro-soft pseudopotential method based on the density function theory. It is found that the band structure of GaN(0001) surface changes greatly after relaxation, the surface has metallic conductive properties, and there is obvious surface state near the bottom of conduction band. In the effect of dipole moment, the surface charges shift and Ga-terminated surface is positive polar surface. the surface energy and the work function of GaN (0001) surface are obtained to be 2.1 J.m-2 and 4.2 eV, respectively. The optical properties of GaN (0001) surface and bulk phase GaN are analyzed and compared. It is found that there is big difference between them.
Resonance properties of surface plasmon in the anisotropic metamaterial waveguide
Authors: Zhang Li-Wei  , Zhao Yu-Huan  , Wang Qin  , Fang Kai  , Li Wei-Bin  , Qiao Wen-Tao  ,   School of Physics and Chemistry, Henan Polytechnic University, Jiaozuo 454000, China;,   Pohl Institute of Solid State Physics, Tongji University, Shanghai 200092, China
Published: December 2020

The resonance properties of surface plasmon in the AMM/dielectric/AMM waveguide are theoretically studied by using the finite-difference time-domain technique, where the claddings are anisotropic metamaterial (AMM) . From the dispersion relation, it is found that the AMM/dielectric/AMM waveguide supports TE polarized surface plasmon if AMM is always-cutoff with negative permeability. The wavelength of the surface plasmon becomes shorter when both the thickness of the dielectric core and the magnetic plasma frequency of AMM decrease. For an AMM/dielectric/AMM waveguide with a finite length, a subwavelength plasmon microcavity can be formed by Fabry-Perot resonance caused by the reflection of the guided mode at the entrance and the exit surfaces. At the resonant frequency, the electric field is maximized in the center, the magnetic field is maximized at the dielectric core entrance and exit, and the electromagnetic energy is strongly concentrated around the dielectric core. Such electromagnetic properties will have potential applications in the tunable subwavelength microcavity with strongly localized field and in the cavity quantum electrodynamics.
Tracking refractivity from radar clutter using particle filter
Authors: Sheng Zheng  , Chen Jia-Qing  , Xu Ru-Hai  ,   Institute of Meteorology, PLA University of Science and Technology, Nanjing 211101, China;,   Key Laboratory of Meteorological Disaster of Ministry of Education, Nanjing University of Information Science and Technology, Nanjing 210044, China;,   Nanjing Research Institute of Electronics Technology, Nanjing 210013, China
Published: December 2020

Particle filter(PF) is an effective algorithm for the state recursive estimation in nonlinear and non-Gaussian dynamic systems by utilizing the Monte Carlo simulation, and it is applicable for solving the nonlinear and non-Gaussian RFC(refractivity from radar clutter) problems. The basic idea and the specific algorithm of PF are introduced; the implementation of the iterative inversion algorithm is derived finally. The experimental result indicates that the particle filter is suited to solve the nonlinear inversion problem and can effectively increase the stability and the accuracy of inversion results compared with the extended Kalman filter (EKF) and the unscented kalman filter (UKF).
Homotopy analysis solution of point reactor kinetics equations with six-group delayed neutrons
Authors: Zhu Qian  , Shang Xue-Li  , Chen Wen-Zhen  ,   Department of Nuclear Energy Science and Engineering, Naval University of Engineering, Wuhan 430033, China
Published: December 2020

Homotopy analysis method is a new method to form approximate analytical solution for non-linear system by using various base functions, which is different from traditional analytical methods. So far, the analytical solution of the point reactor neutron kinetics equations with six-group delayed neutrons has not been obtained yet. In this paper the homotopy analysis method is employed for solving the point reactor neutron kinetics equations with six-group delayed neutrons. The series analysis solutions are obtained using the homotopy analysis method, and the relevant algorithm is given and analyzed. The results show that the computation time and accuracy satisfy the engineering requirements. This analysis method can be applied to the design, the analysis and the simulation of reactor control.
Simulation of imaging spectrometers degraded by satellite vibrations
Authors: Tang Qiu-Yan  , Tang Yi  , Cao Wei-Liang  , Wang Jing  , Nan Yi-Bing  , Ni Guo-Qiang  ,   Key Laboratory of Photoelectronic Imaging Technology and System (School of Photoelectricity), Beijing institute of technology, Beijing 100081, China
Published: December 2020

Instability of satellite platform will seriously affect the quality of spectral imaging. The degradation mechanism of interferential and dispersive imaging spectrometers caused by satellite vibrations is studied in this paper. A simulation algorithm of degradation based on differential dynamic spectral imaging is presented. And the concept of mean mixing ratio (MMR) is proposed, which builds the bridge between the parameters of satellite vibration and the influences on spectral imaging. The quantitative relationship between them is also deduced in detail. Spectral degradation results are simulated by taking the typical spectra and the generated spectrums of surface features as the ideal original data. Simulation results show that the effects caused by pitch and roll are much greater than that by yaw, and the vibrations affect not only spatial resolution but also spectrum, and the regions of rich species are influenced seriously.
Design and research of chaotic vibration isolation system under the condition of small displacement
Authors: Jiang Guo-Ping  , Tao Wei-Jun  , Huan Shi  , Xiao Bo-qi  ,   Earthquake Engineering Research Test Center, Guangzhou University, Guangzhou 510405, China;,   Department of Physics and Electromechanical Engineering, Sanming University, Sanming 365004, China
Published: December 2020

A chaotic vibration isolation device under the condition of small displacement is designed according to the chaotic vibration theory.The device can generate strong nonlinearity under small displacement. The linear part and the nonlinear part are completely separated. The overall stiffness, the ratio of linear term to nonlinear term can be easily adjusted. The engineering application scope of the device turns wider. The numerical simulation is carried out with specific parameters. The design is confirmed.
Error analysis of four-quadrant-based tracking sensor when dead zone is inevitable
Authors: Ma Xiao-Yu  , Mu Jie  , Rao Chang-Hui  ,   The Laboratory on Adaptive Optics, Institute of Optics and Electronics, Chinese Academy of Sciences. Chengdu 610209, China;,   The Key Laboratory on Adaptive Optics, Chinese Academy of Sciences, Chengdu 610209, China;,   Graduate University of Chinese Academy of Sciences, Beijing 100039, China
Published: December 2020

Based on the basic principle of four-quadrant-based tracking sensor, the energy detecting rate, centroid detecting error and the displacement sensitivity of four-quadrant detector caused by noise or dead zone are analyzed in detail. The tracking error formula of four-quadrant-based tracking senor is put forward theoretically and verified experimentally. The results show that when the noises are constant, the tracking error of four-quadrant-based tracking senor depends on the ration between the width of Gauss facula and the width of dead zone of four-quadrant detector.
The study of time-resolved measurement using ICCD positioning cosmic rays
Authors: Lü Qi-Wen  , Zheng Yang-Heng  , Tai Cai-Xing  , Liu Fu-Hu  , Cai Xiao  , Fang Jian  , Gao Long  , Ge Yong-Shuai  , Liu Ying-Biao  , Sun Li-Jun  , Sun Xi-Lei  , Niu Shun-Li  , Wang Zhi-Gang  , Xie Yu-Guang  , Xue Zhen  , Yu bo-Xiang  , Zhang Ai-Wu  , Hu Tao  , Lü Jun-Guang  ,   Institute of Theoretical Physics, Shanxi University, Taiyuan 030006, China;,   Graduate University of Chinese Academy of Sciences, Beijing 100049, China;,   Institute of High Energy Physics, CAS, Beijing 100049, China
Published: December 2020

Double layers of 150 mm?150 mm plastic scintillator arrays are used to locate the cosmic ray. Both layers of arrays are read out by wavelength-shifting fibers, which are bundled and coupled to image intensifier and ICCD camera. The light signal is delayed more than 200 ns by the image intensifier, so the ICCD can be pre-triggered by an external fast coincident signal. This cosmic ray positioning system is used to measure the time resolution and photon transfer time of the time-of-fly detector for the common test platform based on cosmic ray. Compared with traditional cosmic rays test, the data-taking efficiency of this system increases more than 30 times because of multi-point readout and higher position resolution. The test results show that the time resolution of the time-of-fly detector is better than 200 ps, which satisfies the requirement of the common platform based on cosmic ray.
A basic theory for the interference of wave packets reflected from stationary and moving boundaries
Authors: Yang Lin-Ping  , Su Zhao-Bing  , Li Ming-Chiang  ,   Institute of Physics, Chinese Academy of Sciences 100190, China;,   Institute of Theoretical Physics, Chinese Academy of Sciences 100190, China
Published: December 2020

In this paper, the interference of wave packets reflected from a stationary boundary and a moving boundary respectively are discussed. The present theory is based on the boundary value problem of classical electrodynamics, especially with the moving boundary which gives rise Doppler effect. Various distinguished interference properties are investigated and a rigorous expression for the velocity measurement of the moving mirror is provided. At the end, the paper points out that many similar and important problems are waiting for us to explore.
Experimental study of the evolution of phase vortices in the speckle fields generated by weak scattering screens in the extremely deep Fresnel diffraction region
Authors: Chen Xiao-Yi  , Liu Man  , Li Hai-Xia  , Zhang Mei-Na  , Song Hong-Sheng  , Teng Shu-Yun  , Cheng Chuan-Fu  ,   College of Physics and Electronics, Shandong Normal University, Jinan 250014, China;,   School of Physics and Technology, University of Jinan, Jinan 250022, China;,   School of Mathematical and Physical Sciences, Shandong Institute of Light Industry, Jinan 250353, China;,   Department of Information Science and Technology, Shandong University of Political Science and Law, Jinan 250014, China;,   School of Science, Shandong Jianzhu University, Jinan 250101, China
Published: December 2020

The amplitude of speckles which are in the extremely deep Fresnel diffraction region and generated by weak scattering screens is extracted. It is found that when scattering distance is fixed, the property of phase distribution varies with weak scattering screen roughness. For a weak scattering screen, the phase distribution property changes with scattering distance. The phase votex phenomenon does not appear until the surface of weak scattering screen is rough enough. It is interesting that there are phase vortices on scattering screen surface. The phase votex density will rise when scattering screen becomes rougher or scattering distance turns larger. Experimental results are helpful to realize that the phase and the phase votex distribution property vary with roughness of weak scattering screen and scattering distance which lies in the extremely deep Fresnel diffraction region. Moreover, the results contribute to the understanding of the speckle field evolution with scattering distance.
Effects of external magnetic field and temperature on low frequency photonic band width in cryogenic superconducting photonic crystals
Authors: Li Chun-Zao  , Liu Shao-Bin  , Kong Xiang-Kun  , Bian Bo-Rui  , Zhang Xue-Yong  ,   College of Information Science & Technology, Nanjing University of Aeronautics & Astronautics, Nanjing 210016, China;,   State Key Laboratory of Millimeter Waves, Southeast University, Nanjing 210096, China;,   Zhenjiang Watercraft College, Zhenjiang 212003, China
Published: December 2020

Superconducting photonic crystals are artificial periodic structures composed of superconductors and dielectric structures. In this paper, the transfer matrix method(TMM) is used to study the transmittance of one-dimensional photonic crystals consisting of cryogenic superconductor and lossless dielectric for TM wave. It is shown that a stop band staring from zero frequency can be apparently observed, whose cutoff frequency is adjusted by varying the temperature and the magnetic field. However, because of the contribution of the normal conducting electrons (NCEs) , taking no account of external magnetic field, the width of the low frequency photonic band gap (PBG) is no longer influenced by the temperature of the superconductor. The cutoff frequency of PBG adjusted by the temperature and the external magnetic field with the contribution of NCEs are compared with those obtained by neglecting them. However, when superconductors are in a normal state, the low frequency PBG of photonic crystals disappears.
The bubble velocity research of Rayleigh-Taylor and Richtmyer-Meshkov instabilities at arbitrary Atwood numbers
Authors: Tao Ye-Sheng  , Wang Li-Feng  , Ye Wen-Hua  , Zhang Guang-Cai  , Zhang Jian-Cheng  , Li Ying-Jun  ,   State Key Laboratory for GeoMechanics and Deep Underground Engineering, China University of Mining and Technology, Beijing 100083, China;,   Institute of Applied Physics and Computational Mathematics, Beijing 100088, China;,   Center for Applied Physics and Technology , Peking University, Beijing 100871, China;,   Beijing Forestry University, Beijing 100083, China
Published: December 2020

We generalize the Layzer's bubble model to the cases of two-dimensional and three-dimensional analytical models of an arbitrary interface Atwood number and obtain self-consistent equations. The generalized model provides a continuous bubble evolution from the earlier exponential growth to the nonlinear regime. The asymptotic bubble velocities are obtained for the Rayleigh-Taylor(RT) and Richtmyer-Meshkov(RM) instabilities. We also report on the two-dimensional and the three-dimensional analytical expressions for the evolution of the RT bubble velocity.
The influence of Hall drift to the ionization efficiency of anode layer Hall plasma accelerator
Authors: Geng Shao-Fei  , Tang De-Li  , Qiu Xiao-Ming  , Nie Jun-Wei  , Yu Yi-Jun  ,   Southwestern Institute of Physics, Chengdu 610041, China
Published: December 2020

The Hall drift of electrons in anode layer plasma accelerator is analyzed based on Lorentz transformation. It is shown that Hall drift does not exist always in the cross-field. If the ratio of E to B is lager than light speed, Hall drift will disappear. The further analysis shows that the Hall drift is not always in the form of gyration. It is also in the forms of wave and straight line, depending on electric-magnetic field configuration and initial energy of electrons. The electric-magnetic configuration determines the speed of drift, and then affects electron energy. This can determine the ionization efficiency in discharge. A numerical simulation using the Particle-in-Cell method is performed. The result indicates that a nice ratio of E and B will produce high ionization efficiency (for argon, this value is about 4106). This value will change with working gas according to the ionization cross section determined by electron energy.
Use the subthreshold-current technique to separate radiation induced defects in gate controlled lateral pnp bipolar transistors
Authors: Xi Shan-Bin  , Lu Wu  , Wang Zhi-Kuan  , Ren Di-Yuan  , Zhou Dong  , Wen Lin  , Sun Jing  ,   Xinjiang Technical Institute of Physics & Chemistry CAS, Urumqi 830011, China;,   Xinjiang Key Laboratory of Electronic Information Materials and Devices, Urumqi 830011, China;,   Graduate University of Chinese Academy of Sciences, Beijing 100049, China;,   State key Laboratory of Analog Integrated Circuit, Chongqing 400060, China
Published: December 2020

In this paper, we design and fabricate a new test structure of bipolar device. A gate is deposited on the oxide layer covering the base region of normal lateral pnp bipolar transistor. The characteristic of drain current (collector current) versus the gate voltage is recorded by sweeping the voltage applied to the gate, then the subthreshold-current technique is used to separate the radiation induced oxide trapped charges and interface traps in the gate controlled lateral pnp bipolar transistor during 60Co- irradiation. The test structure and the measurement of the bipolar transistor used in the experiment are introduced in detail in this paper.
The effect of doped nitrogen and vacancy on thermal conductivity of graphenenanoribbon from nonequilibrium molecular dynamics
Authors: Yang Ping  , Wang Xiao-Liang  , Li Pei  , Wang Huang  , Zhang Li-Qiang  , Xie Fang-Wei  ,   School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013, China
Published: December 2020

Graphene has become one of the most exciting topics of nano-material research in recent years because of its unique thermal properties. Nitrogen doping and vacancy defects are utilized to modify the characteristics of graphene in order to understand and control the heat transfer process of graphene. We use nonequilibrium molecular dynamics to calculate the thermal conductivity of armchair graphenenanoribbon affected by nitrogen doping concentration and nitrogen doping location, and analyze theoretically the cause of the change of thermal conductivity. The research shows that the thermal conductivity drops sharply when graphenenanoribbon is doped by nitrogen. When nitrogen doping concentration is up to 30%, the thermal conductivity drops by 75.8%. When the location of nitrogen doping moves from the cold bath to the thermal bath, the thermal conductivity first decreases and then increases. And it is also found that the structure of triangular single-nitrogen-doped graphenenanoribbon is inhibited more strongly in the heat transfer process than that of parallel various-nitrogen-doped graphenenanoribbon. Vacancy defects reduce the thermal conductivity of graphenenanoribbon. When the location of vacancy moves from the cold bath to thermal bath, the thermal conductivity first decreases and then increases. When the vacancy position is located at 3/10 of the entire length relative to the edge of the cold bath, the thermal conductivity reaches a minimum value. This is because of the phonon velocity and phonon mean free path varying with the concentration and the location of nitrogen doping and the location of vacancy defect. These results are useful to control the heat transfer process of nanoscalegraphene and provide theoretical support for the synthesis of new materials.
Adsorption and diffusion of oxygen on Pt (111) surface and subsurface
Authors: Lv Bing  , Linghu Rong-Feng  , Song Xiao-Shu  , Wang Xiao-Lu  , Yang Xiang-Dong  , He Duan-Wei  ,   School of Physics and Electronic Science, Guizhou Normal University, Guiyang 550001, China;,   Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, China;,   School of Physics and Electronic Science, Guizhou Normal College, Guiyang 550001, China
Published: December 2020

The adsorption and the diffusion of oxygen on the Pt (111) surface and subsurface are basic issues to understand oxidation and corrosion, which are investigated based on the density functional theory and the periodic slab model. The absorption structure is analyzed through scanning tunneling microscopy (STM) image. The diffusion processes of oxygen atoms on Pt (111) surface and subsurface are discussed in detail using the CI-NEB method. The results show that the diffusion of oxygen atoms over Pt (111) surface is easier than the diffusion into the subsurface, which is mainly because the diffusion of the subsurface needs to go through a layer of Pt atoms and must overcome a certain energy barrier. Transition metal Pt is indicated to have a strong antioxidant activity.
First-principles study on the doped concentration effect on electron lifespan and absorption spectrum of Eu-doping anatase TiO2
Authors: Li Cong  , Hou Qing-Yu  , Zhang Zhen-Duo  , Zhang Bing  ,   College of Sciences, Inner Mongolia University of Technology, Hohhot 010051, China;,   Department of Physics, Mudanjiang Normal University, Mudanjiang 157012, China
Published: December 2020

Based on first principles within the density-functional theory, we establish three different concentration Eu-doping anatase TiO2 models by using the plane-wave ultrasoft pseudopotential method. We calculate the density of states, the electron density difference, the band structure and the absorption spectrum. The results show that Eu creates an impurity level in the band gap of TiO2 and a redshift in absorption spectrum of anatase TiO2. By comparing the bands of anatase TiO2, with two different Eu-doping concentrations (1.39 at% and 2.08 at%) we find that more Eu atoms make the impurity level deeper, the recombination rate bigger, and the electron lifespan shorter.
Study of electron density of nanostructure metal Tm
Authors: Hou Bi-Hui  , Liu Feng-Yan  , Jiao Bin  , Yue Ming  ,   College of Applied Science, Beijing University of Technology, Beijing 100124, China;,   college of Materials Science and Engineering, Beijing University of Technology, Beijing 100124, China
Published: December 2020

Electron density is an important parameter for the macroscopic properties of metal. The reflectance spectrum measurement and the Hall Effect measurement are basic experiments for obtaining electron density and carrier density. Two samples (sample 1:100 nm, sample 2:10 nm) of nanostructure block rare earth metal Tm are studied. Their reflectivity spectra show that the surface reflection of Tm metal possess metallic optical properties in a region of infrared-ultraviolet, the electronic densities np of 6s band are 2.434 1028/m3 and 1.7011028/m3 similar to that of alkali. The carriers measured by Hall Effect experiment are of cavity tipe in the two samples, and the carrier densities nH are 8.0321024/m3 and 7.6791024/m3 respectively. They are only states near the Fermi surface. In addition, the conductance of Tm block is three orders of magnitude higher than one of semiconductor. The grain nanostructurization makes electronic density np, conductance , and carrier density nH decrease, but Hall coefficient RH increase.