bluuebunny/crossref_metadata_2025 huggingface dataset:
Precise measurements of rotational constants of the pure long range state of ultracold cesium molecules
Authors: Ma Jie  , Chen Peng  , Liu Wen-Liang  , Feng Guo-Sheng  , Li Yu-Qing  , Wu Ji-Zhou  , Xiao Lian-Tuan  , Jia Suo-Tang  ,   State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser Spectroscopy, Shanxi University, Taiyuan 030006, China
Published: December 2020

The high resolution spectrum of ultracold Cs2 pure long range 0g- state is experimentally measured using modulated trap loss spectroscopic technology. Based on Double photoassociation spectroscopic technique, precise frequency difference reference signals are constructed to accurately calibrate the resonant frequency intervals of the ro-vibrational levels, thus obtaining the relationship between the frequency interval of rotational level and the rotational quantum number. The experimental data are fitted by the non-rigid rotational model, and the molecular rotational constants corresponding to different vibrational levels in the ultracold Cs2 pure long range 0g- state are acquired. The experimental results demonstrate a linear decrease of the rotational constant with the increase of vibrational quantum number, and the linear decreasing rate is -0.41m MHz0.01 MHz.
Parametric excitation and stability of crystalline undulator radiation
Authors: Li Xiu-Ping  , Wang Shan-Jin  , Chen Qiong  , Luo Shi-Yu  ,   College of Electronic Engineering, Dongguan University of Technology, Dongguan 523808, China
Published: December 2020

Looking for a new light source, especially short-wavelength coherent light source has attracted much attention. A possibility and basic conditions are discussed by using crystalline undulator field radiation as a short-wavelength laser; it is pointed out that the short-wavelength laser has not yet been available so far which is due to not only technical reasons, but also physical reasons. In this paper, the physical problem is analyzed by using parametric excitation method. Introducing the sine-squared potential, the particle motion equation is reduced to a pendulum equation with a damping term and parameter excitation term in the framework of classical mechanics and the dipole approximation. A stability of the system is discussed using Melnikov method, and the critical condition of the system is also analyzed. The results show that the stability of the system relates to its parameters. By adjusting these parameters appropriately, the stability of the system can be ensured in principle.
Orthogonal multicarrier M-ary cycle shift keying spread spectrum underwater acoustic communication
Authors: Yin Yan-Ling  , Zhou Feng  , Qiao Gang  , Liu Song-Zuo  ,   Science and Technology on Underwater Acoustic Laboratory, Harbin Engineering University, Harbin 150001, China;,   College of Underwater Acoustic Engineering, Harbin Engineering University, Harbin 150001, China
Published: December 2020

To solve the problem of low bandwidth efficiency of underwater acoustic spread spectrum communication, a multicarrier modulation scheme combined with M-ary spread spectrum and cycle shift keying (CSK) is proposed in this paper. The code sequences chosen by M-ary modulation are then modulated by CSK, simultaneously, they are modulated by the orthogonal multicarrier. The approach enhances the bandwidth efficiency greatly. The performances of the system with m-sequence, Kasami-sequence, and Gold sequence as the code sequence are compared over the underwater acoustic multipath channel with the same data rate and the same bandwidth. The simulations and the results of pool experiment show that m-sequence as the code sequence performs best and Gold sequence performs worst. The number of the m-sequence is limited. In order to increase the data rate further and make the performances of other sequences close to the m-sequence, a new approach to suppressing the inter-carrier interference (ICI), named multiple sequences, is proposed. The approach can greatly suppress the ICI caused by multipath and make the performance close to the performance of the m-sequence.
A rapid inversion scheme for seabed single parameter using time-domain impulse response
Authors: Qu Ke  , Hu Chang-Qing  , Zhao Mei  ,   China Shanghai Acoustic Laboratory, Institute of Acoustics, Chinese Academy of Sciences, Shanghai 200032, China;,   University of Chinese Academy of Sciences, Beijing 100190, China
Published: December 2020

Compared with multi-dimension inversion, the single parameter inversion has the main advantages that inversion complexity decreases with the number of parameters increasing. Firstly, the slop of bottom loss versus grazing angle FdB is proposed to serve as a single parameter. Secondly, in terms of mode and ray paths, the relation between impulse response and seabed reflection loss property FdB is discussed. Finally, a time-domain inversion method using least-squares fitting to intensity decay rate is designed accordingly. Experimental data in North Yellow Sea are inverted. The inverted results are evaluated by the core samples. Good agreement is also obtained between measurement and predictions of transmission losses with using the inverted result. As this method only requires single hydrophone and comparatively few measurements, it is believed to provide a rapid but robust estimation of FdB which can meet the need for many applications.
Numerical study of collision process between two equal diameter liquid micro-droplets using a modified smoothed particle hydrodynamics method
Authors: Jiang Tao  , Lu Lin-Guang  , Lu Wei-Gang  ,   Department of Mathematics, College of Hydraulic Science and Engineering, Yangzhou University, Yangzhou 225002, China;,   Department of Applied Mathematics, Northwestern Polytechnical University, Xi’an 710129, China
Published: December 2020

In this work, the dynamical collision process between two miscible/immiscible micro-droplets is simulated by a modified smoothed particle hydrodynamics (C-SPH) method. In order to improve the numerical accuracy and stability of traditional SPH method, a kernel gradient modified scheme without kernel derivative is considered. Meanwhile, an improved surface tension technique based on the van der Waals model is adopted to deal with the moving interface. The reliability of C-SPH method of simulating the deformation process between two droplet collisions is tested through the numerical simulations of coalescence process between two miscible Newtonian droplet collisions. Subsequently, the coalescence process of miscible polymer droplet collision and the deformation process of bouncing and separation between two immiscible droplet collisions are investigated, in which the control equations of droplets are all based on the van der Waals model. The influences of the collision velocity, collision angle and the density ratio on the deformation process of collision are discussed, and the changes of liquid bridge and rotation angle are analyzed.
Study on continuous vortices induced by sub-microsecond pulsed surface dielectric barrier discharge plasma
Authors: Che Xue-Ke  , Nie Wan-Sheng  , Zhou Peng-Hui  , He Hao-Bo  , Tian Xi-Hui  , Zhou Si-Yin  ,   Department of Space Equipment, Academy of Equipment, Beijing 101416, China
Published: December 2020

The experiments to generate vortices continuously using sub-microsecond pulsed surface dielectric barrier discharge (SDBD) actuator are conducted by particle image velocimetry (PIV). The double-frequencies actuation mode is presented which includes repetitive pulse frequency and vortex frequency. It is found that the empty zone of PIV particles appears in the place where the particles are quite few even nil during the experiments. When discharges occur the primary empty zone is produced by the micro explosion due to the released heat of plasma, and when discharges end the secondary empty zone appears. The induced flow is farther apart form wall and the influence of wall friction should be suppressed due to primary empty zone. When the secondary empty zone on the left side of actuator exposed electrode is blown away completely, the next actuation can start. In order to control the flow more effectively, the pulse voltage with higher repetitive frequency should be applied. The pulse number during one vortex time should be more than 10. As the pulse number increases, the maximal velocity of induced flow increases but the momentum transfer efficiency decreases. The mechanisms releasing heat and body force can be triggered by using the sub-microsecond pulse SDBD actuator.
Absolute measurement of pulsed radiation imaging
Authors: Zhao Ji-Zhen  , Ouyang Xiao-Ping  , Sheng Liang  , Wei Fu-Li  , Zhang Mei  ,   Northwest Institute of Nuclear Technology, Xi’an 710024, China
Published: December 2020

A high transmittance, flat energy spectrum response detector is designed. The relationship between the image and absolute intensity of the pulse radiation is established via a detector, which simplifies the calibration of the absolute measurement in the imaging system. And a new technical approach to the absolute imaging diagnosis for the pulsed radiation is developed. The experiments show that the uncertainty of the absolute intensity measured by this technology is 33%.
Variations of implosion asymmetry with hohlraum length and time in indirect-drive inertial confinement fusion
Authors: Li Hang  , Pu Yu-Dong  , Jing Long-Fei  , Lin Zhi-Wei  , Chen Bo-Lun  , Jiang Wei  , Zhou Jin-Yu  , Huang Tian-Xuan  , Zhang Hai-Ying  , Yu Rui-Zhen  , Zhang Ji-Yan  , Miao Wen-Yong  , Zheng Zhi-Jian  , Cao Zhu-Rong  , Yang Jia-Min  , Liu Shen-Ye  , Jiang Shao-En  , Ding Yong-Kun  , Kuang Long-Yu  , Hu Guang-Yue  , Zheng Jian  ,   CAS Key Laboratory of Basic Plasma Physics and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China;,   Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

In order to achieve the high density compression in laser indirect-drive inertial confinement fusion, the implosion symmetry and hohlraum radiation uniformity are strictly required. To study the variations of implosion asymmetry with hohlraum length and time, three kinds of hohlraum lengths are adopted in experiment. X-ray emission from capsule fuel is measured by an X-ray framing camera. Based on measured capsule compression process and ellipticity variation, it is preliminarily judged that the medium hohlraum of 1700 μm long is the closest to implosion symmetry demand of Shenguang Ⅲ prototype laser facility. Time-resolved implosion asymmetry is derived from a simplified analytic model, in which used is the time-resolved hohlraum radiation nonuniformity derived from a view-factor code. The derived results of the time-resolved implosion asymmetry are basically in agreement with experimental results. The physical mechanism for how hohlraum radiation nonuniformity evolution induces the variations of implosion asymmetry with hohlraum length and time is analyzed.
Diffusion of order reconstruction induced by 1/2 wedge disclination in a thin hybrid nematic liquid-crystal cell
Authors: Lu Li-Xia  , Zhang Zhi-Dong  , Zhou Xuan  ,   Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China;,   University of Chinese Academy of Sciences, Beijing 100049, China;,   School of Science, Hebei University of Technology, Tianjin 300401, China
Published: December 2020

Based on the Landau-de Gennes theory, the diffusion of order reconstruction induced by 1/2 wedge disclination in a thin hybrid cell is investigated by the relaxation iterative method. The core structure, the biaxial structure, and the diffusion of order reconstruction as the cell thickness decreases, are explored. The defect structure and the range of order reconstruction do not change when the cell thickness is larger than 15. As the thickness decreases from 15, the defect range broadens along the substrate direction, and the biaxial region as well as the range of order reconstruction also enlarges. When the thickness further decreases to below the critical value of 10, the biaxial region and the order reconstruction range merge into an entire cell, where the planar orientation is abruptly converted into the perpendicular one across the biaxial wall. The results obtained in this paper are important for further studying the regulating effect of topological defect on submicron colloidal particles in nematics.
Thermal conductivity of carbon nanotube cable type composite
Authors: Tang Jing-Jing  , Feng Yan-Hui  , Li Wei  , Cui Liu  , Zhang Xin-Xin  ,   School of Mechanical Engineering, University of Science and Technology Beijing, Beijing 100083, China;,   Beijing Key Laboratory of Energy Saving and Emission Reduction for Metallurgical Industry, University of Science and Technology Beijing, Beijing 100083, China
Published: December 2020

For single-wall carbon nanotubes filled with gold nanowires, a kind of carbon nanotube cable type composite material, its thermal conductivity is simulated by non-equilibrium molecular dynamics method. The Tersoff potential is employed for C-C bonding interactions, the Lennard-Jones potential for C-Au interactions and the embedded atom method potential for Au-Au interactions. It turns out that the electronic thermal conductivity (ETC) of gold nanowire is much lower than that of the composite with the same size, so the ETC of metal nanowire could be ignored. The carbon atoms tend to vibrate along the axial direction of the tube because of the interaction between gold and carbon atoms. Furthermore, the umklapp scatterings among phonons are reduced and the phonon mean free path is increased. Therefore, the thermal conductivity of the composite is 20%45% higher than the bare carbon nanotubes in a temperature range of 100500 K, but the growth rate decreases with the rise of temperature. The thermal conductivity of the composite rises with the increasing of length but in a sharper rate, and decreases with the increasing of diameter in the same rate, which is similar to the bare carbon nanotubes.
The effect of additional permanent magnet magnetizing methods on magnetic field distribution and the levitation force of single domain GdBCO bulk superconductor
Authors: Ma Jun  , Yang Wan-Min  , Wang Miao  , Chen Sen-Lin  , Feng Zhong-Ling  ,   Department of Physics Qinghai Normal University, Xining 810008, China;,   College of Physics and Information Technology, Shaanxi Normal University, Xi’an 710062, China
Published: December 2020

It has been investigated that the interaction force between a cubic permanent magnet PM1 and a GdBCO bulk (HTSC) superconducting permanent magnet (SCPM) magnetized by a cubic permanent magnet PM2 under different configurations at 77 K. Two configurations were used for the magnetization of the GdBCO bulk, one is that the North pole of the PM2 is in upward direction, the other is in downward direction, so that the North pole of the SCPM is in two states SCPM↑ and SCPM↓; the vertical distance between the bottom surface of PM1 and the top surface of SCPM is kept as a constant value, but the PM2 can be fixed at any positions (x) along a diameter of the GdBCO bulk during the magnetization process. It is found that: for the PM1↓-SCPM↑ configuration, the maximum levitation force is increasing from 16.7 N to 23.1 N when x increases from –15 mm to 0, and then decreases to 16.6 N when x further increases to 15 mm; but for the PM1↓-SCPM↓ configuration, the maximum levitation force is decreasing from 17.7 N to 7 N when x increases from –15 mm to 0, and then increases to 17.6 N when x further increases to 15 mm. These results are not only much different in the two configurations, but also much different from the maximum levitation force 17.1 N of the sample under zero field cooled condition, which is closely related with the trapped field distribution of the SCPM at different x values. These results indicate that the levitation force of high temperature bulk superconductors can be effectively improved by introducing additional permanent magnet based on scientific and reasonable designing of the system configurations, which is very important during the practical design and applications of superconducting magnetic levitation systems.
Micromagnetic analysis of the effect of the easy axis orientation on demagnetization process in Nd2Fe14B/α-Fe bilayers
Authors: Xia Jing  , Zhang Xi-Chao  , Zhao Guo-Ping  ,   College of Physics and Electronic Engineering, Sichuan Normal University, Chengdu 610068, China
Published: December 2020

The hysteresis loops and energy products in the magnetization reversal process are investigated by one-and three-dimensional micromagnetic methods for a Nd2Fe14B/α-Fe bilayer system with an angle β between the applied field and the easy axis, and the results are compared with available experimental results. The calculation shows that the deviation of the easy axis affects the magnetization reversal process seriously. When β≠0°, there is no obvious nucleation in the magnetization reversal process. The remanence decreases as β decreases, and the squareness of the hysteresis loops is weakened, leading to the sharp decrease of energy product. For Nd2Fe14B(10 nm)/α-Fe(8 nm), the energy product decreases by 30.3% when β=10°. In the magnetization reversal process, as the total energy reaches the maxium, Zeeman energy decreases with increasing of β, and the exchange energy first increases and then decreases slightly, and the anisotropic energy increases with the increasing of β. The deviation of easy axis has a greater influence on the energy product of the bilayer system with larger soft thickness. The out-of-plane deviation of easy axis has a similar effect.
Lie symmetry analysis of the time fractional Boussinesq equation
Authors: Yu Xing-Jiang  , Liu Xi-Qiang  ,   School of Mathematical Sciences, Liaocheng University, Liaocheng 252059, China
Published: December 2020

We have applied the Lie group analysis method to the time fractional Boussinesq equation. This equation can be reduced to an equation which is related to the Erdelyi-Kober fractional derivative by Lie method as a result. It is shown that the approach introduced here is effective and easy to implement.
The traveling wave approximate solution for a class of atmospheric wading wave system by generalized variational iteration
Authors: Shi Lan-Fang  , Zhou Xian-Chun  , Mo Jia-Qi  ,   College of Mathematics and Statistics, Nanjing University of Information Science & Technology, Nanjing 210044, China;,   College of Electronic and Information Engineering, Nanjing University of Information Science & Technology, Nanjing 210044, China;,   Jiangsu Technology and Engineering Center for Meteorological Sensor Network, Nanjing University of Information Science and Technology, Nanjing 210044, China;,   Jiangsu Key Laboratory of Meteorological Observation and Information Processing, Nanjing University of Information Science and Technology, Nanjing 210044, China;,   Department of Mathematics, Anhui Normal University, Wuhu 241003, China
Published: December 2020

In this paper, a class of wading wave system is considered. Firstly, the corresponding functional is constructed; secondly, its Lagrange operators are selected. Then, using the modified generalized variational iteration method, the corresponding traveling wave approximate analytic solutions are obtained.
Optimal control for a chaotic system by means of Gauss pseudospectral method
Authors: Cao Xiao-Qun  ,   School of Computer Science, National University of Defense Technology, Changsha 410073, China
Published: December 2020

A new numerical method is presented to solve optimal control problem of a chaotic system based on Gauss pseudospectral method (GPM). Firstly, the Lagrange interpolation polynomials are constructed on Legendre-Gauss nodes and used to parameterize the state and control the trajectories in optimal control of the chaotic system. Then, the chaotic optimal control problem in the continuous space is transformed into a nonlinear programming (NLP) problem through GPM. Furthermore, the NLP problem is solved by the sequential quadratic programming algorithm. Finally, the proposed method is applied to the optimal control of the typical Lorenz, Chen, and Liu chaotic systems respectively. The simulation processes indicate that the GPM is effective, fast and feasible for solving optimal control problems of chaotic systems.
A new double-wing fractional-order chaotic system and its synchronization by sliding mode
Authors: Wang Bin  , Wu Chao  , Zhu De-Lan  ,   College of Water Resources and Architectural Engineering, Northwest A & F University, Yangling 712100, China
Published: December 2020

Firstly, a new fractional-order chaotic system is proposed. When the linear term x in the second formula of the system was replaced by its absolute value, the range of its unique parameter k that makes the wing of the original system doubled is explored in detail. Furthermore, the numerical simulation and the circuit simulation of the original system and its double-wing system are achieved via Matlab and Multisim software respectively. Finally, based on sliding mode control theory and stability theory in fractional calculus, a new sliding mode controller is designed to realize the synchronization of the new system and its double-wing system respectively. Simulation results are provided to illustrate the effectiveness of the proposed scheme.
Spatio-temporal synchronization of parameter mismatch system based on differential geometry theory
Authors: Tan Ping-An  , Yang Lei  , Zhang Bo  ,   College of Information Engineering, Xiangtan University, Xiangtan 411105, China;,   College of Electric Power, South China University of Technology, Guangzhou 510640, China
Published: December 2020

A new nonlinear synchronization control strategy for a parameter mismatch system based on exact linearization via feedback is presented. First, a nonlinear affine model of parameter mismatch system is established, and the precondition of exact linearization is verified based on the differential geometry theory. Through the nonlinear coordinate transformation, the linear decoupling system is obtained, so the state feedback control law can be determined by the linear optimal control theory. It is found by simulation results that the proposed synchronization method based on exact linearization via feedback can ensure the successful control of the parameter mismatch system.
Optimization in design of actively shielded whole-body open high-field superconducting MRI magnet
Authors: Feng Zhong-Kui  , Hu Ge-Li  , Xu Ying  , Zhu Guang  , Zhou Feng  , Dai Yin-Ming  , Wang Qiu-Liang  ,   University of Chinese Academy of Sciences, Beijing 100049, China;,   Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190, China
Published: December 2020

We propose an optimization design method for actively shielded whole-body open high-field superconducting MRI magnet which accordingly has been simplified to contain only four pairs of superconducting coils. The new design method of open structure superconducting MRI magnet integrates the linear programming algorithm and the genetic algorithm optimization. Through several times of linear programming, and by taking into account the magnetic field, inhomogeneity in DSV, the scope of 5-Gauss fringe field, maximum hoop stress and maximum magnetic field, we can, with the least consumption of lines, get the coils’ initial position and shape, the number of layers of each coil and the number of turns of each layer. And the genetic algorithm was then employed to improve the magnetic field inhomogeneity in DSV to meet the requirements of high-quality imaging. This integrated optimization design method is flexible and effective for designing both open MRI magnet and traditional cylindrical MRI magnet. This paper also illustrates the method for a 1.2 T open MRI magnet optimization design.
First principle study on B-Al co-doped 3C-SiC
Authors: Zhou Peng-Li  , Shi Ru-Qian  , He Jing-Fang  , Zheng Shu-Kai  ,   College of Electronic and Informational Engineering, Hebei University, Baoding 071002, China;,   Research Center for Computational Materials, Hebei University, Baoding 071002, China
Published: December 2020

The lattice parameters, band structure, density of states, effective mass, carrier concentration and electrical resistivity of 3C-SiC in different doped forms (undoped, B-doped, Al-doped and B-Al co-doped) are calculated using the plane wave ultrasoft pseudopotential based on density functional theory. Calculations indicate that as the B or Al replaces Si atoms, both the conduction band and valence band shift to higher energy level. The top of valence band shifts quicker, resulting in the decrease of the band gap. B-Al co-doped 3C-SiC shows the narrowest bandgap while the pure one has the widest. Effective mass of B-doped 3C-SiC decreases but that of Al-doped 3C-SiC increases; while B-Al co-doped 3C-SiC effective mass, whose value approaches to the undoped, can be understood in terms of different compensation. As the acceptor impurities, B and Al will greatly increase the carrier density of valence band top, and the carrier density of the co-doped is three times as Large as the B-doped or Al-doped 3C-SiC. In addition, B-Al co-doping has the lowest resistivity among the four doping forms displaying its significant advantages in electrical property.
TDDFT studies on CO in a linear polarized femtosecond laser field
Authors: Wang Zhi-Ping  , Zhu Yun  , Wu Xin  , Wu Ya-Min  ,   School of Science, JiangNan University, Wuxi 214122, China
Published: December 2020

We present a theoretical study on the ionization and excitation dynamics of CO in various linear-polarized laser fields with in the frame work of the time-dependent density functional theory (TDDFT), applied to valence electrons, coupled non-adiabatically with molecular dynamics of the ions. It is found that the stronger the laser intensity, the more the energies are absorbed by CO and the earlier the ionization takes place with more electrons emitted. Moreover, the bond length of CO is stretched associated with more violent contraction vibration. The dipole moment along the laser polarization is enlarged when the laser intensity is enhanced. This study on the influence of the polarization of laser pulse on the excitation of CO indicates that the ionization of CO is maximized and the contraction vibration becomes most violent when the laser is polarized along the molecular axis. Ionization is restrained when the polarization angle is increased and the dipole vibration shows a strong dependence on the laser polarization. Furthermore, it is found that the electron density surrounding the carbon atom is distributed along the molecular axis particularly when the dispersion of the electrons around the oxygen atom is greatly influenced by the laser polarization.
Studies on the R-branch emission spectral lines of VN molecules
Authors: Fu Jia  , Fan Qun-Chao  , Sun Wei-Guo  , Hu Shi  , Jiang Yong-Hong  ,   School of Physics, Sichuan University, Chengdu 610065, China;,   School of Physics and Chemistry, Research Center for Advanced Computation, Xihua University, Chengdu 610039, China
Published: December 2020

Vanadium nitride is an important metallurgical additive and a good electrode material. Studying its interior microstructure is necessary for fully understanding its intrinsic nature and for better applications. Two groups of known experimental transition data of low-lying rotational quantum states and the analytical formula derived by Sun group in their previous works are used in this work to predict the high-lying accurate R-branch emission spectra of the (0, 0) band in the f1Φ–a1Δ and d1∑+–X3Δ1 systems of the VN molecule. Theoretical results not only reproduce all known experimental spectral lines accurately, but also generate correct values of the unknown spectral lines up to J=80 that are not available experimentally. This study defines a contribution degree C to measure the contributions of known experimental spectral lines to the predicted line. The contribution degree C makes it easier for one to understand the relationships and influences among the transition lines (rotational states) of the given system.
Theoretical study on angular distribution and polarization characteristics of X-ray emission following dielectronic recombination of lithium-like ions
Authors: Wang Jin-Xia  , Shi Ying-Long  , Zhang Deng-Hong  , Xie Lu-You  , Dong Chen-Zhong  ,   Key Laboratory of Atomic and Molecular Physics & Functional Materials of Gansu Province, College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070, China;,   Joint Laboratory of Atomic and Molecular Physics, Northwest Normal University and Institute of Modern Physics of Chinese Academy of Sciences, Lanzhou 730070, China
Published: December 2020

Based on the multiconfiguration Dirac-Fock method and the theory of density matrix, we have calculated the magnetic sublevel captured cross section of intermediate doubly-excited state 1s2s22p3/2J = 1 formed by dielectronic recombination of lithium-like ions (26 Z 92). Then, we obtain the angular distribution and linear polarization of X-rays of electric-dipole radiation 1s2s22p3/2J = 11s22s2J = 0. In this study, emphasis is placed on the effects of the Breit interaction on the relevant physical quantities. We find that the influences of the Breit interaction on the alignment for the capture to the doubly-excited state 1s2s22p3/2J = 1 are dramatic, resulting in the remarkable change in the angular distribution and polarization properties of the X-ray emission.
Systematic studies on the field enhancement effect of Hertzian microcracks
Authors: Cai Yue-Fei  , Lü Zhi-Wei  , Li Sen-Sen  , Wang Yu-Lei  , Zhu Cheng-Yu  , Lin Dian-Yang  , He Wei-Ming  ,   Institute of Opto-Electronics, Harbin Institute of Technology, Harbin 150001, China
Published: December 2020

In order to study the effect of micro-cracks on the damage growth, the different field enhancements of the Hertzian micro crack are investigated by varying its angle, width, and depth. Simulation results show that the most harmful cracks are those with inclination angles from 20.9° to 45°, and the cracks with an angle less than 45° and larger than 48.2° are also harmful, but the cracks with inclination angle of 45° are the least harmful. Increasing the depth of the Hertzian cracks will lead to their field enhancement factors increasing with a quadratic relationship. However, increasing the width does not make it essential to the increase of its field enhancement ability. The development of micro-cracks can be approximated by increase its depth and width, so the development of cracks will lead to the increase of its light field modulation capability, and also to its damage growth rate to accelerate, following an exponential law.
Temperature characteristics of VCSEL with liquid crystal overlay
Authors: Wang Qiang  , Guan Bao-Lu  , Liu Ke  , Shi Guo-Zhu  , Liu Xin  , Cui Bi-Feng  , Han Jun  , Li Jian-Jun  , Xu Chen  ,   Laboratory of Opto-electronics Technology, College of Electronic Information and Control Engineering, Beijing University of technology, Beijing 100124, China
Published: December 2020

The 850-nm vertical-cavity surface-emitting laser (VCSEL) with liquid crystal overlay is presented utilizing the birefringence of nematic liquid crystal. Threshold current, peak of optical power and I-P characteristics at different temperatures were studied. At 293 K, the current between the first polarization hop and the second one has an increase of 2.2 mA after overlaying the liquid crystal. At 313 K and 3 mA, the optical power difference between the two orthogonally polarized lights increases from 133.6 to 248.8 μW. The experimental results show that the nematic liquid crystal enlarges the stable range and the discrete of optical power of orthogonally polarized state. Our research could provide insight into the design and fabrication of VCSEL with stable polarization at high temperatures.
Macroscopic physical meaning of entransy and its application
Authors: Zhao Tian  , Chen Qun  ,   Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Engineering Mechanics, Tsinghua University, Beijing 100084, China
Published: December 2020

It is an important approach to solve energy problem by improving performance of heat transfer process. The macro physical meaning of new physical quantity for heat transfer process optimization “entransy” is analyzed by comparing it with interrelated concepts in mechanics. From three aspects: the connection of entransy and the external heat transfer ability, efficiency of heat transfer process defined by entransy, and the relation of heat transfer driving force with entransy, the macro physical meaning of entransy is derived, which is the potential energy of heat in the temperature field. Moreover, the application of entransy theory in engineering is introduced through entransy theory optimization in convective heat transfer.
Influence of diamond on heat dissipation capability of slow-wave structure of helix TWT
Authors: Liu Yan-Wen  , Wang Xiao-Xia  , Zhu Hong  , Han Yong  , Gu Bing  , Lu Yu-Xin  , Fang Rong  ,   The Institute of Electronics, Chinese Academy of sciences, Beijing 100190, China
Published: December 2020

The heat dissipation capability of the slow-wave structure (SWS) of the traveling-wave tube (TWT) is an important influencing factor that restricts the increase of the output power, the stability, and the reliability. Due to several unique and fascinating characteristics, the diamond material has been employed in the SWS manufacture to enhance the thermal conduction to a certain extent. The influences of the supporting rods deposited with diamond film, the helix deposited with diamond film, and the diamond supporting rods on the heat dissipation capability have been studied using theoretical, simulation, and experimental methods. This method is closely associated with the computer simulation in experimental test and increases the simulation accuracy. Valuable conclusions have been obtained.
Bifurcation and chaos in some relative rotation systems with Mathieu-Duffing oscillator
Authors: Hou Dong-Xiao  , Zhao Hong-Xu  , Liu Bin  ,   Department of Control Engineering Northeastern University at Qinhuangdao, Qinhuangdao 066004, China;,   College of Information Science and Engineering, YanShan University, Qinhuangdao 066004, China
Published: December 2020

The dynamic equation of relative rotation nonlinear dynamic system with Mathieu-Duffing oscillator is investigated. Firstly, the bifurcation response align of the relative rotation system under primary resonance-basic parameters condition is deduced using the method of multiple scales, and a singularity analysis is employed to obtain the transition set of steady motion. Secondly, a global bifurcation of the system, some probable routes leading to chaos and multiple times leading to chaos with parametric and external excitation amplitude changes have been discussed by using Melnikov method, and the necessary condition for chaotic motion of the system is presented. Finally, a numerical method is employed to further prove the effectiveness of the theoretical research.
Electronic properties of graphene nanoribbons with periodical nanoholes passivated by oxygen
Authors: Zeng Yong-Chang  , Tian Wen  , Zhang Zhen-Hua  ,   School of Physics and Electronic Science, Changsha University of Science and Technology, Changsha 410114, China
Published: December 2020

By using the first-principles method and the density-functional theory, the electronic properties of graphene nanoribbons(GNRs) with periodic nanoholes passivated by oxygen are studied. It is shown that for the zigzag graphene nanoribbon (ZGNR) in nonmagnetic state(NM), the metallic properties not only still remain but also are obviously enhanced after the holes are punched. But for the antiferromagnetic-state (AFM) ZGNR, after punching holes, it would be changed from semiconductor to metal. While for the ferromagnetic-state (FM) ZGNR, it can be transformed from metal to semiconductor or semimetal after punching holes. Besides, for the punched armchair graphene nanoribbon (AGNR), its band gap will be significantly widened. The in-depth analysis shows that these results are due to the effects of oxygen atoms on electronic properties of GNRs, and also due to the different quantum confinement effects from the neck subprime nanoribbon (NSNR) and edge subprime nanoribbon (ESNR) with different width and edge shape(zigzag or armchair). These findings are important for developing nano electronic devices.
Damage and structural defects in the surface lager of pure molybdenum induced by high-current pulsed electron beam
Authors: Ji Le  , Yang Sheng-Zhi  , Cai Jie  , Li Yan  , Wang Xiao-Tong  , Zhang Zai-Qiang  , Hou Xiu-Li  , Guan Qing-Feng  ,   College of Material Science and Engineering, Jiangsu University, Zhenjiang 212013, China
Published: December 2020

High-current pulsed electron beam (HCPEB) technique was applied to induce the surface irradiation of pure molybdenum. Microstructures and damaging effect of the irradiated surface were investigated in detail by X-ray diffraction, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). After 1 pulse of HCPEB irradiation, a high level of residual stress is amassed in the irradiated surface layer, while after several pulses of irradiation, a large number of adiabatic shear bands are formed on the unmelted regions of the surface, and local cracking occurs in these regions. Microstructure observations show that scattered dislocations and large amounts of vacancy clusters are formed on the irradiated surface. The adiabatic shear bands are composed of fine recrystallized grains with an average size about 1 μm. The partial softening of the irradiated surface induced by adiabatic shear bands, and the segregation of interstitial atoms in grain boundaries are primarily responsible for the surface cracking of the material. Further, nanocrystallines (20 nm) are also formed in some melted regions of the surface.
Mechanism and optimal design of a high-k dielectric conduction enhancement SOI LDMOS
Authors: Wang Xiao-Wei  , Luo Xiao-Rong  , Yin Chao  , Fan Yuan-Hang  , Zhou Kun  , Fan Ye  , Cai Jin-Yong  , Luo Yin-Chun  , Zhang Bo  , Li Zhao-Ji  ,   College of Microelectronic and Solid-State electronic, University of Electronic Science & Technology, Chengdu 610054, China
Published: December 2020

A high-k dielectric conduction enhancement SOI LDMOS is proposed and investigated by simulation. The high-k dielectric pillars are located at sidewalls of the drift region. The high-k dielectric assists the self-adapted depletion in the drift region, reshapes the electric field distribution, and makes the three-dimensional RESURF effect realized in a high-voltage blocking state. Dependences of the breakdown voltage (VB) and the specific on-resistance (Ron,sp) on device parameters are exhibited using three-dimensional simulation. Simulation results show that the proposed structure increases VB by 16%–18% and decreases Ron.sp by 13%–20%, compared with the conventional super-junction SOI LDMOS. Furthermore, the charge-imbalance caused by the substrate-assisted depletion effect is alleviated.
A polarization-independent and ultra-broadband terahertz metamaterial absorber studied based on circular-truncated cone structure
Authors: Mo Man-Man  , Wen Qi-Ye  , Chen Zhi  , Yang Qing-Hui  , Li Sheng  , Jing Yu-Lan  , Zhang Huai-Wu  ,   State Key Laboratory of Electronic Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, China;,   National Key Laboratory of Science and Technology on Communication. University of Electronic Science and Technology of China, Chengdu 610054, China
Published: December 2020

In this paper, we present an ultra-broadband polarization-independent terahertz (THz) metamaterial absorber (MA) made of circular truncated cone metamaterial. Absorptivity higher than 92.3% at normal incidence is obtained in a wide range of frequencies from 2 to 10 THz. We employ an isotropic metamaterial cell which consists of alternating layers of Au metal and SiO2 dielectric spacer. The absorption spectra of the THz MA are calculated using the finite-difference time domain (FDTD) method within the CST Microwave Studio 2009 in the frequency range of 0–10 THz. Our broadband absorber can be regarded as a group of micro-absorbers perpendicularly stacked and their absorption peaks coupling to each other to form an ultra broadband absorption. This THz MA has the advantages of broadband, polarization-independent and fabrication facility, and thus can be widely applied in THz wave harvesting, detection, spectrum imaging and stealthy technology.
Simulation and experimental research of phase transmission features based on evanescent field coupled graphene waveguide
Authors: Cheng Yang  , Yao Bai-Cheng  , Wu Yu  , Wang Ze-Gao  , Gong Yuan  , Rao Yun-Jiang  ,   Key Laboratory of Optical Fiber Sensing and Communication, Ministry of Education, School of Communication and Information Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China;,   State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Microelectronics and Solid-State Electronics, University of Electronic Science and Technology of China, Chengdu 610054, China
Published: December 2020

The applications of graphene-based optical waveguide devices have been demonstrated to be one of the important directions of development for a new generation of photonic devices, and the research of graphene-based optical fiber and integrated photonic devices has attracted a great deal of attention at home and abroad. In this paper, a graphene planar optical waveguide is proposed which could transmit light by the evanescent field coupling with a microfiber. Finite element method is adopted to simulate the optical field intensity distribution and phase features of light propagating along graphene planar optical waveguide, and an experiment is performed to verify these features. Experimental results show that the transmission distribution and phases of the evanescent field are modulated by graphene obviously, it could effectively gather and transmit the high-order modes, exhibiting denser equal-phase faces on unit propagating length. In this work, we propose a new method in which the microfiber is adopted to investigate the transmission phase feature of graphene by evanescent wave coupling, which could be used as references for the design and application of graphene-based optical devices, such as modulator, filter, laser and sensor.
Study of a W-band TE62 mode generator by the waveguide mode transformation
Authors: Shen Wen-Yuan  , Wang Hu  , Geng Zhi-Hui  , Du Chao-Hai  , Liu Pu-Kun  ,   Key Laboratory of High Power Microwave Sources and Technologies, Institute of Electronics, Chinese Academy of Sciences, Beijing 100190, China;,   University of Chinese Academy of Sciences, Beijing 100190, China;,   School of Electronics Engineering and Computer Science Peking University, Beijing 100871, China
Published: December 2020

In this paper, based on the theory of mode-matching and the coupled wave theory, A W-band TE62 mode generator by using waveguide mode transformation is presented. Because of the eigen-mode selection of coaxial waveguide, a TE1 mode in standard rectangular waveguide is coupled into a coaxial waveguide to excite a TE61 mode by an aperture. A transition follows on it to change the coaxial waveguide into a circular one. Finally, TE61–TE62 mode converter is achieved by using a periodic radius perturbation in circular waveguide. Calculation and analysis of the relationship between the mode conversion efficiency and structure parameters of waveguide also are finished. The validity of this study is confirmed by using electromagnetic simulation software. The conversion efficiency of TE62 mode reaches 94.5% at the center frequency 95 GHz, and the mode purity reaches 98.16% The bandwidth of the efficiency above 85% reaches 1 GHz, which can meet the demand of the high–frequency cold test of gyrotrons.
The research of the social network evolution based on the evolutionary game theory
Authors: Liu Qun  , Yi Jia  ,   Chongqing key laboratory of computational intelligence, Chongqing University of Posts and Telecommunications, Chongqing 400065, China
Published: December 2020

The development of research on social network makes a great contribution to the study of network evolution though much of the work focuses on a macroscopic evolutionary mechanism. In this paper, based on public goods games, an optimized evolutionary dynamic multi-community network model generated by the co-evolution process of evolutionary games and network topology is put forward (dMCPGG). Edges are revised according to the difference between expected payoff and effective payoff through time. Considering the heterogeneous topology, a new preferential rule based on the topological potential is introduced to quantify the nodes’ importance when choosing and updating the payoff of individuals in the public goods games. Finally, the results of simulations demonstrate that the dMCPGG model can reproduce the random world and scale-free world features, such as the nodes’ degree, clustering coefficient and average path length. Finally, we apply our model to United State Congress voting data and verify its rationality.
Binomial theorem involving Hermite polynomials and negative-binomial theorem involving Laguerre polynomials
Authors: Fan Hong-Yi  , Lou Sen-Yue  , Pan Xiao-Yin  , Da Cheng  ,   Department of Physics, Ningbo University, Ningbo 315211, China;,   Department of Materials Science and Engineering, University of Science and Technology of China, Hefei 230026, China
Published: December 2020

We propose an operator Hermite polynomial method, namely, we replace the arguments of the special function by quantum mechanical operators, and in this way we derive a binomial theorem involving Hermite polynomials and a negative-binomial theorem involving Laguerre polynomials. These two theorems will have essential applications in quantum optics calculations. This method is concise and helpful in deducing many operator identities, which may become a new branch in mathematical physics theory.
Subdiffusive transport of fractional two-headed molecular motor
Authors: Lin Li-Feng  , Zhou Xing-Wang  , Ma Hong  ,   Department of Mathematics, Sichuan University, Chengdu 610064, China;,   College of Computer and Information, Fujian Agriculture and Forestry Uninversity, Fuzhou 350002, China
Published: December 2020

Focusing on the directed transport phenomena of the two-headed molecular motor, we adopt power function as the damping kernel function of general Langevin equation due to the power-law memory characteristics of cytosol in biological cells and present the model of fractional coupling Brownian motor in overdamped condition in this paper. We also discuss the influences of fractional order and coupling factor on the transport speed. From the simulation results there are found the directed transport phenomena and the inverse transport which is not seen in the conventional Brownian motor, in the overdamped fractional coupling Brownian motor. When the noise density is fixed, the generalized stochastic resonance appears when transport speed varies with the fractional order and coupling factor. In particular, the results reveal that the magnitude and direction of the directional flow are controlled by coupling the noise with the interaction force between the two heads, which is the movement characteristic of the two-headed molecular motor in the memory ratchet, rather than of the single-headed motor.