bluuebunny/crossref_metadata_2025 huggingface dataset:
Gravity field model calculated by using the GOCE data
Authors: Su Yong  , Fan Dong-Ming  , You Wei  ,   School of Geoscience and Environment Engineering, Southwest Jiaotong University, Chengdu 611756, China
Published: December 2020

Global static gravitational field determined by GOCE satellite data has become a hotspot in current research of geodesy. In this paper, a global static gravity field model entitled SWJTU-GO01S up to the degree and order 210 is recovered based on 12 months of GOCE orbit and gradient data from 2011-02-28 to 2012-03-05 with direct approach. GOCE gradient data are filtered by the zero phase finite impulse band-pass digital filter, and then a gradient observation equation is founded directly in gradiometer coordinates, which avoids high-accuracy gradient component loss in accuracy in the conversion process, while the orbit data is processed with short-arc integral approach. The optimal weight of combination result based on SST and SGG data is determined by variance component estimation and the polar gaps is dealt with the Kuala regularization method. Comparison of internal and external precision of SWJTU-GO01S with EGM2008 and with GPS leveling data of North America, shows that the geoid error and cumulative error of the SWJTU-GO01S model with the degree and order 210 are 2.1 cm and 13.7 cm respectively. Compared with the second generation models released by ESA and ITG-GRACE2010S, the accuracy of the model SWJTU-GO01S is higher than that of the model ITG-GRACE2010S and ESA official time-wise and space-wise model in the above degree and order 150. This study provides a reference to further joint multi-class satellite observation data to recover gravity field models.
Characteristics of forecast errors in the National Climate Center atmospheric general circulation model in winter
Authors: Wang Hao  , Zheng Zhi-Hai  , Yu Hai-Peng  , Huang Jian-Ping  , Ji Ming-Xia  ,   Key laboratory for Semi-Arid Climate Change of the Ministry of Education, College of Atmospheric Sciences, Lanzhou University, Lanzhou 730000, China;,   Laboratory for Climate Studies of China Meteorological Administration, National Climate Center, Beijing 100081, China;,   Meteorology Department of 94195 PLA, Lintao 730500, China
Published: December 2020

By using the National Climate Center atmospheric general circulation model (BCC_AGCM) for the second generation monthly dynamic extended range system and the NCEP/NCAR reanalysis data accumulated during 1982-2010, the model forecast errors in winter temperature prediction and their relationship with external forcing factors are analyzed. Result indicates that the model can well reproduce the variation trends of winter temperature over Eurasia region, and the main interannual variability pattern of winter temperature over East Asian monsoon domain can be successfully presented. It reveals that the model has acceptable performances in winter temperature prediction over East Asian monsoon domain, while the forecast errors are still considerable. In spatial distribution, the forecast errors over lands are larger than those over oceans. Meanwhile, the errors at high latitudes are larger than at low latitudes, and they are also closely related to altitude. The principal components of forecast errors have significant association with the sea surface temperature and the sea ice concentration over some key regions, it is shown that the response capability to external forcings is insufficient. This may provide a valuable reference for improving the prediction skill of winter temperature for East Asian monsoon domain, in combination with the model response to external forcings.
Fidelity recovery scheme for quantum teleportation in amplitude damping channel
Authors: Yang Guang  , Lian Bao-Wang  , Nie Min  ,   Department of Communication Engineering, School of Electronics and Information, Northwestern Polytechnical University, Xi'an 710072, China;,   School of Telecommunication and Information Engineering, Xi'an University of Posts and Telecommunications, Xi'an 710121, China
Published: December 2020

During the course of quantum teleportation in amplitude damping channel, the quantum Bell entanglement state will suffer a de-coherence, which will lead to the quality decrease of quantum teleportation, or even communication failure. To overcome this influence, we propose a method to compensate for the de-coherence of Bell entanglement state. Based on the parameter estimation of the amplitude damping channel, the compensation is divided into two steps. The first step (called pre-compensation) is carried out before the occurrence of de-coherence; the second step (called match-compensation) is carried out after the quantum entanglement state has experienced the de-coherence in the amplitude damping channel. The former is done at the EPR source device, while the latter is done at the quantum user device. The parameters of pre-compensation and match-compensation are determined by the amplitude damping coefficient. The quantum teleportation is carried out after the entanglement compensation. We will give the theoretical derivation and performance analysis of this method. Compared with the method that has no compensation and the method that the compensation is only done after de-coherence, the method given in this paper has a higher quantum teleportation fidelity which is close to 1, when the compensation parameter is adjusted accurately. Our method shows an effective influence on the teleportation quality decrease due to the entanglement de-coherence.
A BLT equation-based approach for calculating the shielding effectiveness of enclosures with apertures
Authors: Luo Jing-Wen  , Du Ping-An  , Ren Dan  , Nie Bao-Lin  ,   School of Mechatronics Engineering University of Electronic Science and Technology of China, Chengdu 611731, China
Published: December 2020

A calculation method based on BLT equation is proposed for analyzing the shielding effectiveness of enclosures containing apertures. This method can accurately and quickly obtain the shielding effectiveness of oblique incidence and polarization, off-centered apertures, and multi-apertures in two walls of enclosures. Aperture scattering matrix can be obtained according to equivalent circuit theory. Then, propagation relationships and reflection relationships are established, and finally the general BLT equation is derived, including the coupling to apertures. In order to verify the validity, the results are compared with these from equivalent circuit theory and CST. With the same aperture impedance, the aperture scattering matrix contains the interaction of the electromagnetic field so that the method proposed in this paper owns higher precision and can predict more resonant modes compared with the equivalent circuit theory. This method takes less time and computer resource compared with CST which cannot easily get the influence of enclosure parameters.
Study on nonlinear surface waves along the boundary of LiNbO3 crystals
Authors: Chen Wei-Jun  , Lu Ke-Qing  , Hui Juan-Li  , Wang Chun-Xiang  , Yu Hui-Min  , Hu Kai  ,   Institute of Electronics and Information Engineering, Tianjin Polytechnic University, Tianjin 300387, China
Published: December 2020

The propagation of nonlinear surface waves along the boundary of LiNbO3 crystals with diffusion and photovoltaic nonlinearities is investigated theoretically and experimentally. Surface waves with different oscillating period are obtained by changing the values of the propagation constant, and the energy of surface waves would increase monotonically with the propagation constant. Our experimental results are in good agreement with the theoretical analysis. Experimental results show also that the generation of surface waves can be shortened by increasing the power of the input beam; and the excitation efficiency of the surface waves can be enhanced by increasing the angle (less than 90 degree) between the input beam and the crystal c-axis.
Spontaneous emission field excited by an atom near the μ-negative metamaterials slab
Authors: Qin Li  , Li Ze-Ya  , Xu Jing-Ping  , Zhang Li-Wei  , Yang Ya-Ping  ,   MOE Key Laboratory of Advanced Micro-Structured Materials, School of Physics Science and Engineering, Tongji University, Shanghai 200092, China;,   School of Physics and Chemistry, Henan Polytechnic University, Jiaozuo 454000, China
Published: December 2020

This paper discusses the spontaneous emission field of a two-level atom near a μ-negative metamaterial(MNG) slab, in which the surface modes are excited. the μ-negative metamaterial is a kind of artificial-microstructured materials possessing effective negative permeability and positive permittivity. According to Maxwell's equations and boundary conditions, the MNG slab supports only TE-polarized surface modes.We analyze the properties of the surface mode, i.e.the number of the surface mode and its symmetry or antisymmetry profiles, supported by the MNG slab with different permeability and thickness, and then study the influence of these characteristics on the spatial distribution of the spontaneous emission field in detail. Results show that the distance between the atom and the slab can affect the ratio of surface mode to the total atomic emission field. When the surface mode plays the dominate role, the spontaneous emission field of the atom on the nearest surface of MNG slab are directionally propagating along y-axis if the atomic dipole is along x-axis due to the TE-polarized surface mode. The atomic emission field on the other surface depends on the symmetry of the surface modes and their percentage. If the symmetric and antisymmetric surface modes coexist, the field intensity on the right surface is weakened or even disappears completely, but if there exists only symmetric or antisymmetric surface mode, the field intensity on the right surface is nearly identical with that on the left surface. These phenomena are significantly different from the case of atoms near a metal slab or a dielectric slab. Our results are useful for the controllable atomic emission and have potential application to the single-photon source.
Pulsed microwave energy spatial distribution imaging by means of thermoacoustic tomography
Authors: Bi Xin  , Huang Lin  , Du Jing-Song  , Qi Wei-Zhi  , Gao Yang  , Rong Jian  , Jiang Hua-Bei  ,   Shenyang Institute of Automation, Chinese Academy of Sciences, Key Laboratory on Radar System Research and Application Technology of Liaoning Province, Shenyang 110179, China;,   School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054, China;,   Department of Biomedical Engineering, University of Florida, Gainesville, Florida 32611, USA
Published: December 2020

Microwave-induced thermoacoustic imaging is a noninvasive, high contrast, high resolution, and cost effective method for cancer detection. It has the potential to serve as a routine breast tumor screening. In the present study, simulation and experiment have been used for pulsed microwave energy spatial distribution investigation. The target to be imaged is a 99 square array composed of tubes 3 mm in diameter and 8 mm in separation. The simulation and experimental results both indicat that far away from the antenna, more tubes could be thermoacoustically recovered, which means a larger radiation area obtained. The thermoacooustically recovered tubes are 3.1 mm in diameter and 7.7 mm in separation. Obtained results suggest that it is feasible to detect microwave energy spatial distribution with the thermoacoustic imaging, which has paved the way to solve the inhomogeneous microwave energy problem in traditional quantitative thermoacoustic tomography.
Stability of surfactant-laden droplet spreading over an inclined heterogeneous substrate
Authors: Li Chun-Xi  , Chen Peng-Qiang  , Ye Xue-Min  ,   Key Laboratory of Condition Monitoring and Control for Power Plant Equipment, North China Electric Power University, Baoding 071003, China
Published: December 2020

For the spreading of a droplet covered with insoluble surfactant over an inclined random heterogeneous substrate, the base state and disturbance evolution equations for the film thickness and surfactant concentration are derived using the lubrication theory. Stability of the droplet spreading on the heterogeneous substrates, and effects of dimensionless parameters as well as the internal mechanism are investigated based on the non-modal stability theory. Results show that the disturbances of film thickness and surfactant concentration exihibit a double-hump shape and the crests lie in thinning regions at the bottom of the droplet. With increasing disturbance wave number, the stability of the droplet spreading is enhanced, but the maximal disturbance transfers from the right-side to the left-side of the droplet bottom. Increasing inclined angle leads to severe instability distinctly. Improving topographical height or increasing wave number of the substrate leads the spreading stability to firstly enhance and then to weaken. The droplet evolution displays an unstable spreading under smaller capillary number, with the maximum disturbance to be increasing before decreasing.
Experimental study on flow visualization of hypersonic flat plate boundary layer
Authors: Fu Jia  , Yi Shi-He  , Wang Xiao-Hu  , Zhang Qing-Hu  , He Lin  ,   College of Aerospace Science and Engineering, National University of Defense Technology, Changsha 410073, China
Published: December 2020

The classical problem of flat plate boundary layer which involves turbulence and transition is still hot, and a mass of work should be done to reach a high accuracy measurement of this flow, especially under the condition of high velocity. In the present paper, the application of the nano-based planar laser scattering (NPLS) method in a hypersonic short-duration facility is explored, and then the high accuracy measurement of a flat plate boundary layer is studied. The Mach number of the main flow is 7.3, the total pressure is 4.8 MPa, and the total temperature is 680 K. Through analysis and tests, the synchronization control of the NPLS system with the test facility is realized, and with the quantitative control, the tracer particle is uniformly seeded. Based on this, the transient boundary layer flow in the short-duration tunnel is visualized with high resolution, and the transition from laminar to turbulent flows is captured. The development characteristic of the flow is studied finally.
Phenomenological modeling of nanosecond pulsed surface dielectric barrier discharge plasma actuation for flow control
Authors: Zhao Guang-Yin  , Li Ying-Hong  , Liang Hua  , Hua Wei-Zhuo  , Han Meng-Hu  ,   Science and Technology on Plasma Dynamics Laboratory, Aeronautical and Astronautical Engineering College, Air Force Engineering University, Xi'an 710038, China
Published: December 2020

One-zone inhomogeneous phenomenological nanosecond dielectric barrier discharge (NS-DBD) actuation model used for flow control simulation is established to investigate the flow control mechanisms, based on experiments and theoretical analysis. When the inhomogeneous phenomenological model is applied to a plate, the formation of spanwise vorticity is analyzed through the vorticity transport equation, and the spanwise vorticity is mainly engendered due to the baroclinicity of pressure gradient and density gradient, also due to the vorticity transfer by the flow convection in the vicinity of the actuation region. Agreement of the simulation with experiments on a column shows that the inhomogeneous phenomenological NS-DBD actuation model is reasonable. Separation control over NACA 0015 airfoil at high angle of attack indicates that the spanwise vortices induced by plasma actuation make the separated shear layer instable, promote interaction between shear layers, and downstream the separation point. Different excitation frequency has different effect on the lift, with the optimum reduced frequency F+ ≈ 6 in current simulation.
Numerical investigations on the interaction of shock waves with spherical SF6 bubbles
Authors: SHA Sha  , Chen Zhi-Hua  , Zhang Qing-Bing  ,   Key Laboratory of Transient Physics, Nanjing University of Science. &Technology., Nanjing 210094, China;,   Beijing Institute of Electronic System Engineering, Beijing 100854, China
Published: December 2020

Based on the simulation of large eddy current, combined with the high-precision computational scheme, the study of planar shock wave and reflected shock waves at different reflected distances, which interact with spherical SF6 bubbles, is carried out numerically in 3D. Our numerical results show clearly the deformation of spherical interface that is induced by the Richtmyer-Meshkov instability due to the collision of shock wave. Jets induced by incident shock wave and reflected shock waves are revealed, and the flow field of the interactions between the reflected shock waves at different reflected distances and the SF6 bubbles is also discussed in detail.
Structure and phase change in Cu-Ge3Sb2Te5 films for use in phase change random access memory
Authors: Sun Jing-Yang  , Wang Dong-Ming  , Lü Ye-Gang  , Wang Miao  , Wang Yi-Man  , Shen Xiang  , Wang Guo-Xiang  , Dai Shi-Xun  ,   Faculty of Information Science and Engineering, Ningbo University, Zhejiang 315211, China
Published: December 2020

The Cu-Ge3Sb2Te5 thin films with different Cu contents were prepared by magnetron sputtering method. The dependence of film resistance on temperature is measured in situ by using the four-point probe heating platform. The crystal structure, microstructure, optical gap, and bond states of the Cu-Ge3Sb2Te5 films are investigated by X-ray diffraction, transmission electron microscopy, transmission and Raman spectra, respectively. It is shown that the crystallization temperature and activation energy of crystallization increase with increasing Cu content, suggesting the improvement in thermal stability and data retention ability, while optical gap decreases with increasing Cu concentration. It is observed that the Raman peak shifts from 129 cm-1 to 127 cm-1, which may be ascribed to the vibration of polar Cu–Te bonds. The Cu-Ge3Sb2Te5 crystallizes into the embedded Cu2Te and Ge2Sb2Te5 phases with evenly grown grains.
Effects of layer thickness and strain rate on mechanical properties of copper-gold multilayer nanowires
Authors: Fan Qian  , Xu Jian-Gang  , Song Hai-Yang  , Zhang Yun-Guang  ,   School of Science, Xi'an University of Posts and Telecommunications, Xi'an 710121, China;,   College of Materials Science and Engineering, Xi'an Shiyou University, Xi'an 710065, China
Published: December 2020

Effects of individual layer thickness and strain rate on the mechanical behavior of copper-gold multilayer nanowires as well as the dislocation nucleation mechanism under a uniform tensile loading are investigated using molecular dynamics method. Simulations indicate that the highest yield strength increases with the increase of the individual layer thickness. Furthermore, the result also shows that the mechanical properties in the tensile process at different strain rates are dramatically different from each other, where the dislocation motion and twinning deformation are at a lower strain rate, while the individual atoms are at a higher strain rate for leading to amorphization. The general conclusions derived from this work can provide a guideline for the design of high performance multilayer composite materials.
Critical properties of the S4 model for Sierpinski carpet
Authors: Yin Xun-Chang  , Liu Wan-Fang  , Zhu Zu-Song  , Kong Xiang-Mu  ,   School of Physics and Electric Engineering, Anqing Teachers College, Anqing 246011, China;,   Department of Physics, Qufu Normal University, Qufu 273165, China
Published: December 2020

According to the bond-moving renormalization group technique, the critical behaviour of S4 model for Sierpinski carpet is investigated, then the critical points are obtained. From the results we find that there are a Wilson-Fisher fixed point and a Gaussian fixed point. In contrast to the Gauss model for Sierpinski carpet, the critical points have altered obviously. Results indicate that the two systems belong to two different universal classes.
Simulation studies on the influence of nanofilm thickness on the elastic properties of B2-NiAl
Authors: Yang Xi-Yuan  , Zhang Jin-Ping  , Wu Yu-Rong  , Liu Fu-Sheng  ,   Physics Science and Technology School, Nanling Normal University, Zhanjiang 524048, China;,   College of Physics and Electronics, Hunan University of Arts and Science, Changde 415000, China;,   Department of Materials Science and Engineering, Xiamen University of Technology, Xiamen 361024, China;,   College of Metallurgical Engineering, Hunan University of Technology, Zhuzhou 412007, China
Published: December 2020

In this paper the molecular dynamics (MD) technique and the modified analytic embedded atom method (MAEAM) are applied to study the influence of size and surface condition of the nanofilm on the elastic properties of B2-NiAl, The elastic properties of the bulk NiAl alloy and the size dependence of the surface energy of nanofilms are first calculated. It is found that the calculated results of the elastic properties are consistent with those from experiments and theories; and the surface energy, which is barely influenced by the thickness, is controlled by the surface atomic composition. On this basis, our investigations are mainly focused on the relationship between the elastic properties of nanofilms and their thickness. The obtained results indicate that the elastic properties of the nanofilm may change exponentially with the increasing thickness, which can also be regulated by the surface atomic composition. Furthermore, the inherent mechanism of the thicknes and surface that affects this relationship is analyzed in detail, showing that the surface atomic composition and the deviation of interplanar spacing in nanofims are two major factors for determining the thickness dependence of the elastic properties. These are in good agreement with the previous theoretical and experimental studies.
Molecular dynamics study of ripples in graphene monolayer on silicon surface
Authors: Qin Ye-Hong  , Tang Chao  , Zhang Chun-Xiao  , Meng Li-Jun  , Zhong Jian-Xin  ,   School of Physics and Optoelectronics, Xiangtan University, Xiangtan 411105, China;,   Hunan Key Laboratory for Micro-Nano Energy Materials and Devices, Xiangtan University, Xiangtan 411105, China
Published: December 2020

By using the classical molecular dynamics and the simulated annealing techniques, the evolutions of the rippled morphology in single atomic graphenes placed on the Si (100), Si (111) and Si (211) surfaces respectively are performed at an atomic level. Our results show that the monolayer graphene sheets on the different Si surfaces form atomic scale rippled structures. A graphene monolayer prepared on Si surface forms rippled structure due to the relative lattice mismatch between graphene and Si substrate. The rippled morphology of graphene sheet on Si surface is strongly dependent on the annealing temperature. Such ripples will directly affect the adhesion strength between graphene and Si substrate. These findings are useful for understanding the structural morphology and stability of graphene on the semiconductor Si substrate, which will provide an analysis reference for further applications of graphene.
Researches on the electrical properties of vanadium oxide thin films on Si substrates
Authors: Xiong Ying  , Wen Qi-Ye  , Tian Wei  , Mao Qi  , Chen Zhi  , Yang Qing-Hui  , Jing Yu-Lan  ,   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 of Communication, University of Electronic Science and Technology of China, Chengdu 610054, China
Published: December 2020

Quality enhanced VO2 thin films have been sputtering deposited on silicon substrates by introducing an ultrathin Al2 O3 buffer between the substrate and the film. With a preferred orientation (011), the VO2 films have an excellent thermal-induced metal-insulator transition (MIT). The electrically-driven MIT (E-MIT) characteristics have also been investigated by applying voltage to VO2 thin film based two-terminal device at particular temperatures. Sharp jumps in electric current are observed in the I-V curve with a variation of amplitude by two orders. The threshold voltage decreases with increasing temperature. At room tempature, the threshold voltage is 8.6V and the phase transition ccurs in a voltage width of only 0.1V. With the sharp and fast phase change, the VO2 thin films can be used in ultrafast switching electronic devices.
Effects of Nb doping concentration on TiO2 electricel conductivity and optical performance
Authors: Hou Qing-Yu  , Lv Zhi-Yuan  , Zhao Chun-Wang  ,   College of Sciences, Inner Mongolia University of Technology, Hohhot 010051, China
Published: December 2020

Nowadays, in the reports of Nb heavy-doped TiO2, when the doping mole of Nb is in the range of 0.050 to 0.0625, there is a current controversy between the two experimental results about the minimum resistance of the doped systems. To solve this contradiction, the models of un-doped and the three different concentrations of Nb doped Ti1-xNbxO2 (x=0.03125, 0.050, 0.0625) have been set up based on the first-principles plane wave ultra-soft pseudo potential method of density functional theory; then the geometry optimization of all models is carried out; and the band structures, the density of states, and optical properties are calculated. Results reveal that under the condition of limited doping amount as in this paper, when the doping moles of Nb is increased, the volume, the total energy, and the formation energy of the doped system are increased; the doped system has a lower stability and is hard to be redoped; the relative electronic concentration, and the electron effective mass are increased; the migration rate is reduced, and the conductivity is thus reduced. The wider the optical band-gap, the more obvious the shift of absorption edge to the short wavelength side, the lower the absorptivity and reflectivity; and the transmittance is increased. these are in agreement with the experimental results.
Characteristics of charge transport in nano-sized TiO2 particles/submicron spheres multilayer thin-film electrode
Authors: Jiang Ling  , Zhang Chang-Neng  , Ding Yong  , Mo Li-E  , Huang Yang  , Hu Lin-Hua  , Dai Song-Yuan  ,   Key Laboratory of Novel Thin Film Solar Cells, Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China;,   State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, North China Electric Power University, Beijing 102206, China
Published: December 2020

In this work, we design the nano-sized TiO2 particles/submicron spheres multilayer structured photoanode, based on the fact of stronger light scattering properties of TiO2 submicron spheres. Effect of TiO2 submicron-spheres on the charge transport and interfacial properties in multilayer thin-film electrodes are investigated in detail using intensity-modulated photocurrent spectroscopy (IMPS), electrochemical impedance spectroscopy (EIS) and incident photon-to-current conversion efficiency (IPCE). Results obtained from IMPS for dye-sensitized solar cells (DSCs) indicate that submicron-spheres have fewer defects, but the poor contact at the interfaces between submicron spheres hinders the electron transport and makes the transit time longer. EIS results show that there are no obvious differences in interface recombination between the designed electrodes. It is interesting to find that the bottom section of the photoanode composed of nano-sized TiO2 thin film has a higher light utilization efficiency than that composed of submicron-spheres; meanwhile, the Fermi level of TiO2 and the photovoltaic properties of DSCs have been extended. Our results may provide an experiment basis for structure design of high-efficiency DSC photoanode.
Research on the relationship between ideality factor and number of units of GaN-based high voltage light-emitting diode
Authors: Bai Jun-Xue  , Guo Wei-Ling  , Sun Jie  , Fan Xing  , Han Yu  , Sun Xiao  , Xu Ru  , Lei Jun  ,   Key Laboratory of Optoelectronics Technology, Ministry of Education, Beijing University of Technology, Beijing 100124, China
Published: December 2020

Ideality factor can reflect the current, the carrier leakage, and the phenomenon of non-radiative recombination in light-emitting diode (LED). For the problem of ideality factor from current report about GaN-based LED, the value of ideality factor n is calculated by using the I-V curve fitting of high voltage LED. And the relationship between the ideality factor and the number of units is series in 12, 19, 51 and 80 V GaN-based high-voltage LED are discussed. In addition, the relationship between ideality factor and spectral half width (FWHM) is analyzed, and the impact of current crowding effect on the ideality factor is also studied. Results show that the ideality factor n increases nearly linearly with the number of units in series, indicating that the ideality factor n of high voltage LED is composed of its series units. It is a valuable result for understanding the ideality factor of GaN-based high voltage LED.
Molecular dynamics simulations on the growth of thin amorphous hydrogenated carbon films on diamond surface
Authors: Zhang Chuan-Guo  , Yang Yong  , Hao Ting  , Zhang Ming  ,   Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, China;,   The College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124, China
Published: December 2020

The growth of thin amorphous hydrogenated carbon films (a-C:H) on diamond (111) surface from the bombardment of CH2 radicals is studied using molecular dynamics simulations. Structural analysis shows that the local structure (e.g., the first coordination number of C atoms) of a-C:H depends critically on the content of hydrogen. The increase in kinetic energy of incident radicals leads to the decrease of hydrogen content, which subsequently changes the proportion of sp3 bonded C atoms in a-C:H.
Experimental study on a long pulse X-band coaxial multi-beam
Authors: Liu Zhen-Bang  , Huang Hua  , Jin Xiao  , Yuan Huan  , Ge Yi  , He Hu  , Lei Lu-Rong  ,   Science and Technology on High Power Microwave Laboratory, Institute of Applied Electronics, China Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

An X-band coaxial multi-beam relativistic klystron amplifier is designed in order to increase the output microwave power and the operating frequency of the amplifier tube. Based on the results from PIC simulation, the experiment is performed on the long pulse accelerator. In the experiment, the transmittal and bunching of electron beam are analyzed, and then the amplifier is driven by a beam of 4.2 kA at 700 kV, and an external source injects microwave power of 60 kW into an input cavity, then 670 MW microwave power of 5 Hz repeating frequency is extracted, the amplifier gain is about 40 dB, the pulse width is 89 ns, and the conversion efficiency is 23%. The experiment proves that several tens kW-level input power can drive the X-band coaxial multi-beam relativistic klystron amplifier to generate several hundred MW-level long pulse output power.
Analysis of magnetic disturbance torque and drift error in a superconducting suspension system
Authors: Cui Chun-Yan  , Hu Xin-Ning  , Cheng Jun-Sheng  , Wang Hui  , Wang Qiu-Liang  ,   Institure of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190, China
Published: December 2020

In a superconducting suspension system, the disturbance torque acting on the superconducting rotor may not be generated if the rotor is an ideal sphere and in the complete Meissner state. However, in fact there exist always spherical tolerance during manufacturing process of the sphere and the centrifugal distortion due to the high speed rotation. Therefore, the disturbance torque will be generated due to the magnetic levitation force not getting through the mass center of the rotor when the rotor is levitated in the magnetic field. Based on the physical mechanism of the superconducting-magnetic bearing, the disturbance torque and the drift error are analyzed. The disturbance torques include the main torque due to asphericity of the sphere, the second torque generated by the combination of asphericity, uncentering and assembly errors. The model of drift rate is also deduced and the drift rate is calculated by substituting the rotor parameters into the formula. This analysis provides a reference for the rotor drift testing and error compensation, and is instructive for the optimization design of the rotor structure.
An adaptive global optimization algorithm of cooperative spectrum sensing with relay
Authors: Zhang Qian  , Liu Guang-Bin  , Yu Zhi-Yong  , Guo Jin-Ku  ,   The Second Artillery Engineering University, Xi'an 710025, China
Published: December 2020

In this paper is carried out an investigation that the performance of the cooperative spectrum sensing with relay may be interfered by redundant relays, the number of busy cognitive users (CUs) and the secondary relay(SR), detection threshold and transmission error of the channel, so that a global adaptive optimization algorithm is proposed. In this algorithm, based on the maximum interference-free power relay selection (MIFPRS), the set of secondary relay is defined adaptively; and in order to reach a maximum of the probability of detection, the single cognitive user minimizes the transmission error of the channel and selects the relay from the set of secondary relays. To achieve the maximum of the total channel throughput under the given probability of detection, ale ues the entire adaptive optimization algorithm. Numerical simulations demonstrate that the proposed algorithm has a high degree of channel transmission precision, and a large amount of channel throughput, so as to spend less frequency band.
Honeycomb architecture based mobile fault-tolerant recovery algorithm in WSANs
Authors: Du Jing-Lin  , Zheng Ruo-Qin  , Xie Li  ,   School of Electronic and Information Engineering, Nanjing University of Information Science and Technology, Nanjing 210044, China;,   Department of Computer Science and Technology, Nanjing University, Nanjing 210023, China
Published: December 2020

This paper aims at finding an algorithm in wireless sensor and actor networks (WSANs) to recover the failure actor. First, this paper describes the real-time coverage model in WSANs, proves WSAN's coverage recovery is NP-hard. A cell-based mobile fault-tolerant algorithm HMFR is presented to recover the failure actor, which has a good performance under a limited condition of initial deployment of network. Through simulation experiments, the results show that the algorithm is more effective than the present algorithms in terms of actor coverage and move distance.
Evolutionary gambling dynamics for two growing complex networks
Authors: Xiang Hai-Tao  , Liang Shi-Dong  ,   School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275, China;,   State Key Laboratory of Optoelectronic Materials and Technologies, Guangzhou 510275, China;,   Provincial Key Laboratory of display Materials and Technologies, Guangzhou 510275, China
Published: December 2020

The dynamic complex network is an important model of social structure and stability. Based on the single dynamic complex network, we propose a growing double-network evolutionary gambling model. When the two networks are separated, we find that the average of cooperation strategy has a jump as the payoff increases, which can be regarded as a phase transition. This result is a generalized result of static gambling network. When the two networks are connected, their averages of cooperation strategy are synchronized. When the intra-linkages are increased, the natural selection does not favor cooperation, while the fair selection does. When the inter-linkages are increased, the average of cooperation strategy decreases for both networks. As the ratio of inter- and intra- linkage is constant, the more the average degree, the less the cooperation. We find the existence of defection leader, and uncover its influence on the average of cooperation strategy and how it interacts with cooperation leader. These results provide some hints to understand the social structure, stability and evolution.
Randomness analysis of lane formation in pedestrian counter flow based on improved lattice gas model
Authors: Li Ming-Hua  , Yuan Zhen-Zhou  , Xu Yan  , Tian Jun-Fang  ,   MOE Key Laboratory for Urban Transportation Complex Systems Theory and Technology, Beijing Jiaotong University, Beijing 100044, China;,   Institute of Systems Engineering, College of Management and Economics, Tianjin University, Tianjin 300072, China
Published: December 2020

In this paper, we extend a lattice gas model recently proposed by Li et al, which considers the view field of pedestrian. An improved lattice gas model takes into account the effect of pedestrians' walking preference feature of empty area in the view field to simulate traffic dynamics of pedestrian counter flow. Three dynamic evolution processes under different pedestrian density are reproduced. The randomness of lane formation for different pedestrian density is found, and the probability of lane formation is given. Numerical simulations of relationship diagrams between the probability of lane formation and parameters of the system geometry size, the probability and the proportion of right walker flow, the probability and the strength of the drift, also the probability and the view field size are investigated. Results show that the extended model cannot form for the lane formation under a low pedestrian density, which is associated with the real pedestrian traffic. It is found that the density of pedestrian counter flow could be divided into 5 intervals, and there are differences in the dynamic evolution processes between these 5 intervals. This model and its result is useful for the study of the dynamic evolution process, and is helpful for raising efficiency of pedestrian counter flow in the channel.
An improved high performance Lorenz system and its application
Authors: Guan Guo-Rong  , Wu Cheng-Mao  , Jia Qian  ,   School of Electronic Engineering, Xi'an University of Posts and Telecommunications, Xi'an 710121 China;,   Shaanxi Lingyun Electronics Group Co., Ltd Design Institute, Baoji 721006 China
Published: December 2020

Lorenz system is one of the most typical chaotic system models, and it has been well studied and widely applied. In order to obtain more complex structure and dynamic behavior of chaotic attractor for Lorenz system, improving the Lorenz system has become one of the important tasks in chaotic dynamical system. Therefore, an improved Lorenz system with complex dynamic behavior is proposed and used to protect image information security. Based on the existing various improvement Lorenz systems, firstly, a new Lorenz chaotic system is constructed by increasing the control parameters and modifying nonlinear expression in the existing Lorenz chaotic system; secondly, the mathematical properties of dissipation, symmetry, and stability in the proposed Lorenz system, which are similar to those in the existing Lorenz system, Bao system, Tee system and Y system, are investigated by modern differential dynamical system, and the experimental results of Lyapunov index and random sequence correlation of five different Lorenz systems show that the proposed Lorenz system has a more complex structure and chaotic dynamic behavior; finally, the discrete pseudo random sequences generated by five different Lorenz chaotic systems are used for scrambling the pixel position and diffusing the pixel value to protect image information security. The analyses of correlation and statistic histogram entropy of adjacent pixels, anti-differential attack and key sensitivity of the encrypted image, indicate that the improved Lorenz system proposed in this paper has much better potential advantages than other existing improved Lorenz system in image encryption application.
A novel frequency stabilization method for the seed laser of the pulse optical parametric oscillator in differential absorption lidar
Authors: Ge Ye  , Hu Yi-Hua  , Shu Rong  , Hong Guang-Lie  ,   Key Laboratory of Space Active Opto-Electronics Technology, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083, China;,   State Key Laboratory of Pulsed Power Laser Technology, Electronic Engineering Institute, Hefei 230037, China
Published: December 2020

A novel frequency stabilization method for the seed laser of the pulse optical parametric oscillator (OPO) in differential absorption lidar (DIAL) is proposed in this paper. The operating principle and the experimental setups are introduced in detail, and the accuracy of the frequency stabilization method and influence factors are also analyzed. The frequency of the seed laser is locked to an absorption line of water vapor (935.6849 nm) in the experiment, and the measured standard deviation of the frequency jitter is less than 8 MHz. The frequency of the seeded OPO signal is recorded thereafter. The standard deviation less than 28.7 MHz with the same frequency according to the seed laser is achieved, which is well applicable to DIAL.
Phase singularities in femtosecond laser pulses transmitting through optical fiber probes
Authors: Liu Gui-Yuan  , Song Hong-Sheng  , Zhang Ning-Yu  , Cheng Chuan-Fu  ,   School of Science, Shandong Jianzhu University, Ji'nan 250101, China;,   College of Physics and Electronics, Shandong Normal University, Ji'nan 250014, China
Published: December 2020

The near-field distribution of a light wave in a metal-coated optical fiber probe under the illumination of femtosecond laser pulses is numerically simulated. By choosing the maximum of the calculated light field data and the time when the light field reaches the maximum in a time period of one light wave cycle at each spatial point, we obtain the amplitude and phase distributions of the light field near the probe. We find that the output amplitude distribution of y-polarization has roughly a circled-cross-like pattern with two arc-like zero-amplitude zones. The zeros of light intensity are the phase singularities at which the phase is undefined. By analyzing the output phase distribution of y-polarization, we obtain the temporal evolution of the phase singularities and their characteristics
Image denoising model based on the improved Demons algorithm
Authors: Zhou Xian-Chun  , Wang Mei-Ling  , Zhou Lin-Feng  , Wu Qin  ,   College of Electronic and Information Engineering, Nanjing University of Information Science and 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
Published: December 2020

According to image registration, we build a new Demons model of image denoising, in which the diffusion access is regarded as image registration. The experimental results indicate that the performance of the model is better than that of the Perona-Malik model: the ill-condition of the model is removed. It is not enough to describe local characteristics only by using the gradient information in the access of image denoising, so a level set curvature which is the driving force of image structure controlling is introduced into the denoising model. Therefore we propose a new model of image denoising based on two driving forces of gradient and curvature. The simulation results show that the two improved models can both suppress noise effectively, their definitions are enhanced obviously, the performance of image denoising model of two driving forces is more greatly improved.
Transform relations between squeezed coherent state representation and quantum phase space distribution functions
Authors: Liang Xiu-Dong  , Tai Yun-Jiao  , Cheng Jian-Min  , Zhai Long-Hua  , Xu Ye-Jun  ,   Department of Physics Electronic and Engineering, Chizhou University, Chizhou 247100, China
Published: December 2020

A new operator representation, called squeezed coherent state representation, is introduced since Husimi operator has the form of squeezed coherent state. We fisrt introduce its specific integral expression. When κ = 1, this representation is reduced to the usual P function. As an example, we calculate the squeezed coherent state representation for thermal field to illustrate a difference between P function and the squeezed coherent state representation. Especially, in order to better apply this representation to quantum optics, we reveal the integral transformations between the squeezed coherent state representation, respectively, and the following three functions: Wigner function, Q function, and Husimi function.
Chaotic randomness of mutually coupled vertical-cavity surface-emitting laser by optical injection
Authors: Liu Qing-Xi  , Pan Wei  , Zhang Li-Yue  , Li Nian-Qiang  , Yan Juan  ,   School of Information Science and Technology, Southwest Jiaotong University, Chengdu 610031, China
Published: December 2020

In this paper, a randomness-enhanced chaotic system model of mutually coupled vertical-cavity surface-emitting lasers (VCSELs) is established by adding anothor injected VCSEL with variable polarizer optical feedback (VPOF). The randomness of chaotic signals is evaluated quantitatively by an information-theory-based quantifier, the permutation entropy (PE). The influences of VPOF-VCSEL rotating polarizer degree, feedback strength, injection strength, mutual coupling strength, path time delay and frequency detuning about injected VCSEL and coupled VCSELs on chaotic signal permutation entropy are numerically studied. It is shown that the chaotic signal permutation entropy of mutually coupled VCSEL system driven by the third VCSEL is much higher than the mutual system with no-driving VCSEL. That is to say, the randomness of coupled system chaotic signal can be enhanced by optical injection. When the rotating polarizer degree is approximately 45 degrees and the injection strength is saturated at a constant level, the system PE can be increased by coupled strength, which is set to be higher than feedback strength. In addition, unequal delay time between both coupled time and feedback time, and higher detuning frequency between driving VCSEL and coupled VCSELs can contribute to randomness-enhanced chaotic signals.
Detection of metal element in water using laser-induced breakdown spectroscopy assisted by nebulizer
Authors: Zhu Guang-Zheng  , Guo Lian-Bo  , Hao Zhong-Qi  , Li Chang-Mao  , Shen Meng  , Li Kuo-Hu  , Li Xiang-You  , Liu Jian-Guo  , Zeng Xiao-Yan  , Lu Yong-Feng  ,   Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, China
Published: December 2020

In order to improve the limit of detection and linearity without losing the advantage of on-line and in-situ measurement, laser-induced breakdown spectroscopy assisted by nebulizer is investigated. The influences of the main experimental parameters, namely the defocusing amount, the distance between the nebulizer and the central of laser beam, the ablation energy and the delay are studied to maximize the signal-to-noise ratio. Using laser-induced breakdown spectroscopy assisted by nebulizer, we demonstrate that the detection limits are 1.2, 3.2, 19.1, 3.4, 2.8, and 15.9 ppm for Ca, Cr, K, Mg, Na, Pb respectively, and the linearities are all above 0.99. The results show that laser-induced breakdown spectroscopy assisted by nebulizer is an effective method to detect the tracing metal element in liquid on-line and in-situ.