bluuebunny/crossref_metadata_2025 huggingface dataset:
Wavelength selective optical limiting effect on MoS2 solution
Authors: Wang Yuan-Qian  , He Jun  , Xiao Si  , Yang Neng-An  , Chen Huo-Zhang  ,   Institute of Super-microstructure and Ultrafast Process in Advanced Materials, Department of Physics and Electronics, Central South University, Changsha 410083, China;,   Hunan Key Laboratory for Super-microstructure and Ultrafast Process, Central South University, Changsha 410083, China
Published: December 2020

Using discrete method, N,N-Dimethylformamide (DMF) and tetrahydrofuran(THF) are adopted as solvent to fabricate MoS2 suspension solution, and its nonlinear optical properties in the visible and near infrared region are studied by open aperture Z-scan method. The results show that under the intense laser, in MoS2 (in DMF) suspension solution, saturable absorption property can be detected in the visible waveband (530 nm), showing that its transmittance is 1.54 times of ordinary, and reverse saturable absorption can be observed in the near infrared region (790 nm), indicating that its transmittance is 0.6 time of ordinary one and very good wavelength selection optical limiting effect. As a comparison, in the MoS2 (in DMF) suspension solution there does not appear the wavelength selection feature, but the reverse saturable absorption is present in all band. This phenomena may be produced through the two mechanisms: saturableabsorption and thermally-induced self-diffraction.
Suppression of secondary electron emission by micro-trapping structure surface
Authors: Ye Ming  , He Yong-Ning  , Wang Rui  , Hu Tian-Cun  , Zhang Na  , Yang Jing  , Cui Wan-Zhao  , Zhang Zhong-Bing  ,   School of Electronic and Information Engineering, Xi'an Jiaotong University, Xi'an 710049, China;,   China Academy of Space Technology, Xi'an 710100, China;,   Radiation Detection Research Center, Northwest Institute of Nuclear Technology, Xi'an 710024, China
Published: December 2020

Suppression of secondary electron yield attracted much attention in areas such as accelerator and high power microwave components in recent years. To evaluate the suppression efficiencies of different surface topographies, the secondary electron yields (SEYs) of four kinds of micro-structured surfaces for trapping secondary electrons, i.e., triangular groove, rectangular groove, cuboid, cylindrical, are obtained by the phenomenological probabilistic model of secondary electron emission. The simulation results show that the SEYs of these structures are much dependent on the shape parameters such as aspect ratio or porosity. There are mainly three findings: 1) the SEY decreases with increasing aspect ratio and porosity; 2) the traps with cuboid or cylindrical shape are more efficient than triangular or rectangular traps for the SEY suppression; 3) the SEY dependence of micro-structured surface on incident angle is not as obvious as that of flat surface. Micro-trapping structure surfaces are fabricated by mechanical method, photolithography process and chemical etching respectively. The measured SEYs of these samples validate the theoretical results. All these results show that the proposed micro-structures as secondary electron traps have potential applications in SEY suppression in fields such as multipactor and electron-cloud effects.
Two-dimensional analytical models for the symmetrical triple-material double-gate strained Si MOSFETs
Authors: Xin Yan-Hui  , Liu Hong-Xia  , Wang Shu-Long  , Fan Xiao-Jiao  ,   Key Laboratory for Wide Band Gap Semiconductor Materials and Devices of Education, School of Microelectronics, Xidian University, Xi'an 710071, China;,   Department of Information and Engineering, North China University of Water Resources and Electric Power, Zhengzhou 450045, China
Published: December 2020

A novel double-gate strained Si metal-oxide-semiconductor field-effect transistor (MOSFET), in which the top and bottom gates consist of three laterally contacting materials with different work functions, is proposed in this paper. The two-dimensional (2D) analytical models for the surface potential, surface electric field and threshold voltage are presented. The effects of Ge fraction on surface potential, surface electric field and threshold voltage are investigated. The effects of the triple-material length ratio on threshold voltage and drain induced barrier lowering are discussed. The characteristics of the device are studied by comparing with those of the single-material double-gate MOSFETs. The results show that the structure can increase the carrier transport speed and suppress the drain induced barrier lowering effect. The three-material gate length ratio is optimized to minimize short-channel effect and drain induced barrier lowering effect.
Direct computation of the interaction matrix of adaptive optical system
Authors: Guo You-Ming  , Rao Chang-Hui  , Bao Hua  , Zhang Ang  , Wei Kai  ,   Institute of Optics and Electronics, Chinese Academy of Sciences, Chengdu 610209, China;,   The Key Laboratory on Adaptive Optics, Chinese Academy of Sciences, Chengdu 610209, China;,   University of Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

The interaction matrix of an adaptive optical system is directly computed. In this method, based on the correlation between the measured and theoretical slope influence vectors of the selected actuators, the misalignment between the wavefront sensor and wavefront corrector is first estimated, and then an interaction matrix more close to the real one is obtained. Experimental results show that with considering the misalignment, the interaction matrix acquired by direct computation becomes more effective in closed-loop correction, and the slope residual error is reduced.
Discrepancy between the interactions of nucleons in nuclear matter due to different projection choices of invariant amplitudes
Authors: Xing Yong-Zhong  , Zhao Xing-Wen  , Zheng Yu-Ming  ,   Physics department of Tianshui Normal university, Tianshui 741000, China;,   College of Physics and Electronic Engineering, Northwest Normal university, Lanzhou 730070, China;,   China Institute of Atomic Energy, PO Box 275(18), Beijing 102413, China
Published: December 2020

Dependence of self-energy components and cross sections of nucleons in-medium on the relative momentum of nucleons in nuclear matter from different projections choices of invariant amplitudes is studied within the framework of Dirac-Brueckner-Hartree-Fock model. Special attention is paid to the discrepancy between the self-energies and cross sections for different choices in various separate chances. Our results indicate that the self-energy of nucleons in the states with spin S = 1 and isospin triplets T = 1 is larger than those with S = 0 and T = 0 at a specified relative momentum. The dependence of the self-energies of nucleons in various reaction channels on the pseudo-scalar (PS) choice are more pronounced than that on the complete pseudo vector (CPV) choice, which is mainly due to the states with smaller total momentum quantum numbers J. Results of the in-medium differential cross sections show that the difference between d/d for the neutron-proton and neutron-neutron (or proton-proton) in various choices is larger for smaller relative momentum of nucleons and smaller scattering angles in mass center reference frame However, the total cross section total in the CPV choice is always larger than that in the PS choice. All these discrepancies will disappear with increasing incident energy.
First-principles calculations of the mechanical properties of IrB and IrB2
Authors: Zeng Xiao-Bo  , Zhu Xiao-Ling  , Li De-Hua  , Chen Zhong-Jun  , Ai Ying-Wei  ,   College of Physics and Electronic Engineering, Sichuan Normal University, Chengdu 610066, China;,   College of Electronic Information Engineering, Chengdu University, Chengdu 610106, China;,   School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054, China;,   College of Life Science, Sichuan University, Chengdu 610064, China
Published: December 2020

We have employed ab-initio plane-wave pseudopotential density functional theory to calculate the equilibrium lattice parameters, elastic constants, under the hydrostatic pressures from 0 to 100 GPa for P1 -IrB with Pnma space group and P5 -IrB2 with Pmmn structures. Results show that the P1 -IrB structure is stable, and the incompressibility is enhanced with the increase of pressure. And the elastic constants, bulk modulus, shear modulus for P5 -IrB2 structure exhibit the regular changes under the hydrostatic pressures from 0 to 100 GPa. But when the pressure becomes 50 GPa, the Young's modulus and the lattice constant in the direction b for P5 -IrB2 structure will change exceptionally. Results show that both are not of obvious band gaps in P1 -IrB and P5 -IrB2 electronic structures under zero pressure, because of the covalent effect between Ir and B atoms. The analysis of band structure and the figure of density of states for P1 -IrB and P5 -IrB2 indicate that the two kinds of structure have metal properties.
First-order distorted wave Born approximation for single ionization of Ar by electron impact in a coplanar doubly symmetric geometry
Authors: Zhang Li-Min  , Jia Chang-Chun  , Wang Qi  , Chen Zhang-Jin  ,   School of Physics and Materials Science, Anhui University, Hefei 230601, China;,   Department of Physics, College of Science, Shantou University, Shantou 515063, China
Published: December 2020

The first-order distorted wave Born approximation (DWBA) has been performed for single ionization of Ar(3p) by electron impact in coplanar doubly symmetric geometry from near threshold to intermediate energies. Theoretical triple differential cross sections (TDCS) are compared with the latest experimental data. It is found that when the incident electron energies are 40 eV higher than the ionization threshold, for argon, the binary and recoil collision mechanism will dominat as the energies increase, but not in the near threshold energy regime, where the distortion effects are of great significance. In order to completely describe the electron impact ionization of argon, it is imperative that more scattering mechanisms should be considered in the theoretical models.
Design and study of a multi-funtional electromagnetic device with functions of field rotating and concentrating
Authors: Liu Guo-Chang  , Li Chao  , Shao Jin-Jin  , Fang Guang-You  ,   Key Laboratory of Electromagnetic Radiation and Sensing Technology, Chinese Academy of Sciences, Beijing 100190, China;,   University of Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

A novel multi-functional electromagnetic (EM) device named rotary-concentrator is designed based on transformation optics theory. For its ability to manipulate the EM wave in a special manner, it can rotate the propagation direction of the EM field in the core region to a fixed angle, as well as concentrate the EM energy into the core region simultaneously. For the proposed three equivalent configurations of the rotary-concentrator, the corresponding constitutive parameter expressions are derived respectively, and the full-wave simulations using the finite element software are also carried out. The simulated results validate the derived constitutive parameter expressions. For the three different kinds of configurations, the first two kinds consist of three layers of media, and the last one is simplified to a two-layer configuration. For a given arbitrary rotating angle and an energy concentration ratio, the three configurations can perform propagation direction rotating and energy concentrating in equivalent effect. These results contribute to further understanding of the mechanism of rotator and concentrator, and provide a fuller theoretical basis for the design of multi-functional devices. The proposed rotary-concentrator has potential applications in the design of high efficient receiving antennas and special circuit package interconnecting devices.
Research on speckle denoising by lensless Fourier transform holographic imaging with angular diversity
Authors: Wang Da-Yong  , Wang Yun-Xin  , Guo Sha  , Rong Lu  , Zhang Yi-Zhuo  ,   College of Applied Sciences, Beijing University of Technology, Beijing 100124, China;,   Institute of Information Photonics Technology, Beijing University of Technology, Beijing 100124, China;,   Beijing Engineering Research Center of Precision Measurement & Control Technology and Instruments, Beijing 100124, China
Published: December 2020

The signal-to-noise ratio and resolution of the reconstructed image is seriously influenced by speckle noise in digital holography, so it is essential to reduce the speckle noise and improve the image quality. Intensity correlation between two speckle patterns with the rectangle speckle spot is analyzed and deduced, and the minimal angular difference of illumination beams is given quantitatively under a special situation. A lensless Fourier transform holographic imaging system with angular diversity is designed based on the lens property, in which the direction of the wave can be changed by shifting the fiber instead of conventionally rotating the mirror, and the formor can change the direction of illumination with a fixed illumination size and location. Eighty one holograms with uncorrelated speckle patterns are recorded at different illumination angles by shifting the fiber. Then a digital reconstruction is achieved only by a fast Fourier transform, and the multiple reconstructed images are averaged. Experimental results show that the speckle contrast of the averaged reconstructed image can be reduced to 14.6% that from a single reconstructed image, and the signal-to-noise ratio is improved 6.9 times. This proposed digital holographic imaging method can suppress the speckle noise greatly, has a simple setup, and is easy to operate.
Research on spectral peaks thermal-drifting in multi-wavelength infrared laser diode
Authors: Xue Ming-Xi  , Chen Zhi-Bin  , Wang Wei-Ming  , Ouyang Hui-Quan  , Liu Xian-Hong  , Song Yan  , Zhang Chao  , Xiao Wen-Jian  , Hou Zhang-Ya  ,   Shijiazhuang Mechanical Engineering College, New Technology Application Institute, Shijiazhuang 050003, China;,   China North Standardization Research Center, Beijing 100089, China
Published: December 2020

To meet the requirements, requested in infrared-laser testing techniques, in spectral range and peaks precision of multi-spectral source, we present a method for preparing multi-wavelength infrared laser diode with a high precision, and design a packaging structure which can integrate four kinds of laser chips with wavelengths 860 nm, 905 nm and 1064 nm (pulse/single). The 3D heat conduction differential equations of central-substrate are given based on the above packaging structure. According to the solutions of numerical temperature field distribution, which are solved through a mathematic-modeling tool, the processing technique of central-substrate is optimized. And the prototype of multi-wavelength laser diode is prepared, and the experimental apparatus is built which can be used to observe the phenomenon of spectral peak thermal-drifting. Experimental results show that only two spectral peaks are drifting slightly 13 nm. The drifting amount is within the half width range of their spectral peak. This phenomenon proves that the output spectra of multi-wavelength laser diode have a high precision and a well thermal stability.
Analysis of the tunable filtering properties of a photonic crystal with symmetric dual defects
Authors: Chen Wei-Dong  , Dong Xin-Yu  , Chen Ying  , Zhu Qi-Guang  , Wang Ning  ,   Key Laboratory for Special Fiber and Fiber Sensor of Hebei Province, School of Information Science and Engineering, Yanshan University, Qinhuangdao 066004, China;,   Key Laboratory of Test/Measurement Technology and Instrument of Hebei Province, School of Electrical Engineering, Yanshan University, Qinhuangdao 066004, China
Published: December 2020

A dual channel tunable filter structure has been proposed based on the local characteristic of photonic crystals and the mesoscopic calender effect of photonic crystals. The optical transmission characteristics of the filter have been derived theoretically using the transfer matrix method, and the relationship between the transmission spectrum and structural parameters of photonic crystals has been established. Problems how the mesoscopic calender effect influences the transmission spectrum of photonic crystals with dual defects have been discussed and the structure of photonic crystals has been numerically simulated. The emulational results show that defect modes have a blue shift with the increase of the incident angle, while they have a red shift with the increase of dielectric layers' refractive index or geometrical thickness. When in photonic crystals occurs axial stretched strain, the locations of defect modes will move towards long wavelength side, but the values of defect peaks keep constant generally. Thereby, the filter's tunable property has been verified. This photonic crystal filter with good tunability has a compact structure, which may provide a certain theoretical reference for the design of photonic crystal lasers and sensors.
Dynamical mechanical property of viscoelastic materials and its effect on acoustic absorption of coating
Authors: Lü Lin-Mei  , Wen Ji-Hong  , Zhao Hong-Gang  , Wen Xi-Sen  ,   Vibration and Acoustics Research Group, Science and Technology on Integrated Logistics Support Laboratory, College of Mechatronic Engineering and Automation, National University of Defense Technology, Changsha 410073, China
Published: December 2020

Viscoelastic macromolecular materials are widely used in underwater acoustic fields because of their favorable acoustic performance. Dynamical mechanical properties of viscoelastic materials, such as Young's modulus, shear modulus, and relevant loss factors, are important in the forecast of acoustic properties, which connect acoustical design of underwater coating with materials prescription design. Dynamic Young's modulus of some macromolecular materials is measured with dynamic mechanical apparatus (DMA), and then the basic acoustic parameters are expanded from a narrow band to a broad band by using principles of time-temperature superposition (TTS). When applying the basic parameters to calculating characteristics of the uniform layer sample by using the finite element method, a reasonable agreement of sound absorption coefficients is obtained between the calculations and measurements in the acoustic pipe. Furthermore, the underwater acoustic absorption properties of the coating with a local resonant structure are discussed. Finally, some suggestions are given about how to improve the underwater absorption performance at low frequencies.
Analysis of the tunable liquid gradient index based on optofluidics
Authors: Sun Yun-Li  , Wang Chang-Hui  , Le Zi-Chun  ,   College of Science, Zhejiang University of Technology, Hangzhou 310023, China
Published: December 2020

A new type of tunable gradient-index (GRIN) microfluidic lens is proposed, which is based on the convection-diffusion process. By using the finite element method, the spatial distribution of the refractive-index (RI) determined by the concentration distribution in the microchannel is analyzed. Results show that the distribution of RI in the microchannel can be tuned by different flow rates of the core and cladding liquid streams. Furthermore, although taking into consideration the existence of the viscous resistance between the channel wall and the flowing stream, the RI distribution is still dependent on the combination of flow rates of the core and cladding streams. This microfluidic lens can be applied to dynamic adjustment of focusing, splitting or bending light beams. It therefore may have extensive applications in the optofluidic optical detecting system and microscale imaging system.
Corner vortex characteristics at the reversal of large scale circulation in turbulent Rayleigh-Bnard convection
Authors: Bao Yun  , Ning Hao  , Xu Wei  ,   Department of Mechanics, Sun Yet-sen University, Guangzhou 510275, China;,   Guangdong Ocean University, Zhanjiang 524088, China
Published: December 2020

The two-dimensional Rayleigh-Bnard convection is calculated by DNS method. A large scale circulation and two corner vortices with reverse rotation are presented in soft turbulent convection, and the reversal phenomenon of the large scale circulation appears. Continuous temperature contour and the streamline chart describe the whole process of the reversal clearly. In the process of the reversal, the changes of the corner vortex size play an important role. Analysis of the corner vortex size change shows that the changes appear violent oscillation in the thermal flow field with the reversal, but only slight pulsation is found without the reversal. Corner vortex size, velocity at the typical position, and the temperature near the angle location in the process of reversal are discussed. The reversal is found to be done in an instant, and the velocity pulse is smaller and the temperature is higher in the corner vortex. The corner vortex size and the vertical velocity on the side wall vary synchronistically before the reversal.
A nonlinear plate theory for the monolayer graphene
Authors: Huang Kun  , Yin Ya-Jun  , Wu Ji-Ye  ,   Department of Engineering Mechanics, Faculty of Civil Engineering and Mechanics, Kunming University of Science and Technology, Kunming 650500, China;,   Department of Engineering Mechanics, School of Aerospace, Tsinghua University, Beijing 100084, China;,   Division of Mechanics, Nanjing University of Technology, Nanjing 211816, China
Published: December 2020

In the present paper, the kinematic equation of a monolayer graphene is proposed based on a plate theory, and the nonlinear elasticity stress-strain relations are obtained from experiments. The equation includes cubic and quintic nonlinearities. The bending produced when subjected to a concentrated force at the center of the plate and the static buckling arising from edge in-plane axial uniform loads are investigated using Ritz methods for a simply-supported rectangular plate. Results suggest that the plate theory with nonlinear constitutive equation may characterize the mechanical property of a monolayer graphene appropriately, and the quintic nonlinearities have a significant effect on the bending deformations of the graphene.
Investigation on the bonding behavior of the interface within the supersonic plasma sprayed coating system based on the fractal theory
Authors: Chen Shu-Ying  , Wang Hai-Dou  , Xu Bin-Shi  , Kang Jia-Jie  ,   National Key Lab for Remanufacturing, Academy of Armored Forces Engineering, Beijing 100072, China;,   School of Engineering and Technology, China University of Geosciences, Beijing 100083, China
Published: December 2020

In order to investigate the relationship between the interfacial morphology of the coating system and its adhesion strength, the supersonic plasma spraying equipment is employed to fabricate Fe-based alloy coating. The (Ni, Al) coating is prepared as the undercoating with different flow of Ar gas, aiming at obtaining various rough morphologies. Interfacial morphologies of the coating system are quantificationally characterized by fractal dimension(FD). The pull-off method is used to test the adhesion strength. Result shows that the adhesion strength is obviously improved by fabricating an undercoating, and the FD of the interfacial morphology decreases with the increase of the flow rate of Ar gas, while the adhesion strength will be raised at the first beginning and then decreased to a certain value.
Study on the annealing growth of Ge dots at high deposition rate by using magnetron sputtering technique
Authors: Zhang Xin-Xin  , Jin Ying-Xia  , Ye Xiao-Song  , Wang Chong  , Yang Yu  ,   Institute of Optoelectronic Information Materials, Yunnan University, Kunming 650091, China
Published: December 2020

The 14 nm thick Ge thin films are firstly deposited on Si substrate at 350 ℃ by using the magnetron sputtering technique, then the Ge/Si dots are successfully fabricated by annealing those Ge films. According to the morphology and phonon vibration information obtained by AFM and Raman spectroscopy, the formation and evolution mechanism are studied in detail. Experimental results indicate that the amorphous Ge films have been converted to Ge dots with a density of 8.5109 cm-2 after 675 ℃ annealing for 30 min. By using Ostwald ripening theory, surface diffusion model, and calculation of the activation energy, the surface transfer and the dot formation behavior of Ge atoms can be well interpreted. Based on the fabrication technique of Ge/Si nanodots at a high deposition rate combined with the thermal annealing, we have provided a theoretical support for the experiment on self-assembled growth of Ge quantum dots.
Microstructure and photoluminescence of ZnO：Cd nanorods synthesized by hydrothermal method
Authors: Wang Chang-Yuan  , Yang Xiao-Hong  , Ma Yong  , Feng Yuan-Yuan  , Xiong Jin-Long  , Wang Wei  ,   The Chongqing City Key Laboratory of Optoelectronic Functional Materials, Optical Engineering Key Lab, Chongqing Normal University, Chongqing 400047, China
Published: December 2020

High-quality ZnO and Cd-doped ZnO nanorods with different Cd-doping concentrations are synthesized by using the hydrothermal method. Microstructures and photoluminescence of the samples are systematically investigated by SEM, X-ray diffraction (XRD), Raman scattering spectrum and photoluminescence (PL) spectrum. Results of XRD analysis indicate that ZnO and ZnO:Cd crystallites exhibit a hexagonal wurtzite structure. SEM shows that the nanorods become smaller due to Cd doping. There is an internal tension which induces the decrease of optical band gap in Cd-doped nanorods. Cd-doping increases the intensity of violet emission peak near 2.90 eV and the blue emission peak located at 2.67 eV appears when the doping concentration is up to 2%. This study can be used for developing blue-violet-emitting devices.
Influence of polarization voltage on piezoelectric performance of polypropylene piezoelectret films
Authors: Zhang Tian-Le  , Huang Xi  , Zheng Kai  , Zhang Xin-Wu  , Wang Yu-Jie  , Wu Li-Ming  , Zhang Xiao-Qing  , Zheng Jie  , Zhu Biao  ,   Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology, School of Physics Science and Engineering Tongji University, Shanghai 200092, China;,   Shenzhen Horn Audio Co. Ltd., Shenzhen 518109, China
Published: December 2020

Piezoelectrets are a kind of space-charged electret material with a void-structure. The piezoelectric effect in such a material is related with its microstructure and space charge. In this paper the micro-structure of polypropylene (PP) films is first modified by using a pressed gas expansion process to enhance the charging capability of the films, and then a direct contact charging is carried out to polarize the expanded films. The relationship between the applied voltage and the space charge density, and the influence of the applied voltage on the piezoelectric performance of PP films are investigated. Results show that for 100 m thick modified PP films, the critical voltage necessary for the build-up of the macro-dipoles in the inner voids is approximately 2 kV; once the macro-dipoles are built up, the PP films will exhibit piezoelectric effect. With increasing polarization voltage, the space charge density gradually increases, resulting in significant enhancement of piezoelectric effect. For the PP films polarized at a peak voltage of 8 kV, the space charge density, d33 coefficient, and the figure of merit FOMv(d33 g33) are 0.56 mC/m2, 379 pC/N and 8.6 GPa-1, respectively. Since not only the FOMv of the PP films is almost two orders of magnitude larger than that of PVDF, but also the acoustic impedance in such a material is very low (～ 0.025 MRayl), the PP films have an obvious advantage as applied in airborne ultrasonic transmit-receive or pulse-echo systems.
Investigations of high-quality aluminum film with large-area uniformity for large-size echelle grating
Authors: Li Zi-Zheng  , Yang Hai-Gui  , Wang Xiao-Yi  , Gao Jin-Song  ,   Key Laboratory of Optical System Advanced Manufacturing Technology, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China;,   University of the Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

Large-size echelle grating can have extremely high spectral resolution due to its large aperture and high diffractive order. To achieve high-performance large-size echelle grating, the preparation of high-quality aluminum film with large-area uniformity is one of the most important factors. In this paper, for the first time so far as we know, we report the preparation process of high-quality aluminum with large-area uniformity in details. First, we simulate theoretically the influence of the position and emission characteristic of the evaporation source, as well as the fixture height, on aluminum film uniformity. Then, we study the influence of some key parameters of the evaporation process (such as the evaporation height and rate) on aluminum film quality and uniformity. Finally, under the optimal conditions, we prepared successfully the high-quality aluminum film with its thickness being larger than 10 m and uniformity fluctuations less than 1% within a diameter of 700 mm.
Separation and parameter estimation of single channel sinusoidal frequency modulated signal mixture sources based on particle filtering
Authors: Zhang Shu-Ning  , Zhao Hui-Chang  , Xiong Gang  , Guo Chang-Yong  ,   School of Electronic and Optical Engineering, Nanjing University of Science and Technology, Nanjing 210094, China
Published: December 2020

A signal separation and parameter extraction method based on particle filtering for single channel sinusoidal frequency modulated (SFM) signals is put forward. By assuming that the frequency of SFM signals mixture is continuous, a phase-difference de-aliasing arithmetic based on particle filtering is proposed. And the dimension of state space is reduced by using phase-difference between source signals. A likelihood function model suitable for high dimensional state space is proposed. Particles weight is accurately measured by comparing error between estimated values and true values of particles with fixed length. The problem of particle diversity reduction in the static parameters situation is solved by the introduction of Markov-chain Monte Carlo (MCMC) transfer after re-sampling, and the speed of particle filter iteration convergence is also effectively improved. Single channel SFM signal parameters are extracted and signals are separated by reconstructing signals only with the prior knowledge of modulation type. Finally, the simulation results indicate that this method can separate the multi-component signal sources and estimate the parameters effectively.
Anti-control of Hopf bifurcation in the new chaotic system with piecewise system and exponential system
Authors: Zhang Ling-Mei  , Zhang Jian-Wen  , Wu Run-Heng  ,   College of Mathematics, Taiyuan University of Technology, Taiyuan 030024, China;,   College of Science, North China University of Technology, Beijing 100041, China
Published: December 2020

In order to understand the complex three-dimensional dynamical system with the unstable nodes, we propose a nonlinear controller. The corresponding controlling system makes the codimension one, two, and three Hopf bifurcations happen. The mathematical deduction demonstrates that the system can be controlled to produce the degenerate Hopf bifurcation at desired location and stability of controllable bifurcation.
Combination kernel function least squares support vector machine for chaotic time series prediction
Authors: Tian Zhong-Da  , Gao Xian-Wen  , Shi Tong  ,   College of Information Science and Engineering, Shenyang University of Technology, Shenyang 110870, China;,   College of Information Science and Engineering, Northeastern University, Shenyang 110819, China;,   Department of Humanities, Liaoning Forestry Vocotion-technical College, Shenyang 110101, China
Published: December 2020

Considering the problem that least squares support vector machine prediction model with single kernel function cannot significantly improve the prediction accuracy of chaotic time series, a combination kernel function least squares support vector machine prediction model is proposed. The model uses a polynomial function and radial basis function to construct the kernel function of least squares support vector machine. An improved genetic algorithm with better convergence speed and precision is proposed for parameter optimization of prediction model. The simulation experimental results of Lorenz, Mackey-Glass, Sunspot-Runoff in the Yellow River and chaotic network traffic time series demonstrate the effectiveness and characteristics of the proposed model.
Effects of laser wavelength on both water temperature measurement precision and detection depth of Raman scattering lidar system
Authors: Ren Xiu-Yun  , Tian Zhao-Shuo  , Sun Lan-Jun  , Fu Shi-You  ,   Information Optoelectronics Research Institute, Harbin Institute of Technology at Weihai, Weihai 264209, China
Published: December 2020

Airborne Raman scattering laser lidar technology can measure the three-dimensional (3D) distribution of subsurface seawater temperature rapidly, and it has important social and economic values. In this paper, firstly, the relationship between Raman stretching vibration spectrum peak position and excitation wavelength, and the relationship between the full width half maximum (FWHM) of Raman stretching vibration spectrum and excitation wavelength are analyzed theoretically. The results show that as the excitation wavelength increases, Raman scattering peak gradually shifts toward longer wavelength and the Raman spectrum FWHM increases noticeably. Secondly, to verify the theoretical results, the Raman spectra at different water temperatures excited by 450 nm and 532 nm lasers are measured experimentally, and the fitting analyses of them by single Gauss peak fitting method are made, the relationship between Gauss peak wavelength and temperature is obtained, and the effect of laser wavelength on the temperature measurement precision is analyzed. It is found that larger excitation wavelength can increase Raman spectrum measurement accuracy, thereby improving the temperature measurement precision. Finally, the Raman scattering lidar equation is established, the Raman scattering coefficients and attenuation coefficients of different wavelength lasers are analyzed, and the corresponding effects of laser wavelength on the lidar system detection depth are studied. Results show that the lidar system detection depth is greatly influenced by the laser wavelength, lidar system with laser wavelength below 480 nm has a good detection ability, and large wavelength laser greatly reduces lidar system detection depth. The effects of laser wavelength on both temperature measurement precision and detection depth should be considered in the desigin of Raman scattering lidar system.
Prompt loss of energetic ion in tokamak
Authors: Mou Mao-Lin  , Liu Yu  , Wang Zhong-Tian  , Chen Shao-Yong  , Tang Chang-Jian  ,   College of Physical Science and Technology, Sichuan University, Chengdu 610065, China;,   Southwestern Institute of Physics, Chengdu 610041, China
Published: December 2020

The full orbit of energetic ion in tokamak is simulated by strictly solving Hamiltonian equations in guiding center coordinate system, and the semi-trapped orbit which is predicted in a recent theoretical research and the stagnation orbit are confirmed by the presently developed full orbit theory. The prompt loss of the energetic particle in international thermonuclear experimental reactor is calculated according to the present full orbit theory. It is found that the prompt loss rate of energetic ion in the full orbit theory can be larger than 14% the result in gyro-averaged theory, and the detailed analysis is carried out and physical understanding is presented in this paper.
Effects of Co doping on the magnetic properties, entropy change, and magnetocaloric effect in Mn3Sn1-xCoxC1.1compounds
Authors: Yan Jun  , Sun Ying  , Wang Cong  , Shi Zai-Xing  , Deng Si-Hao  , Shi Ke-Wen  , Lu Hui-Qing  ,   Center for Condensed Matter and Materials Physics, Department of Physics, Beihang University, Beijing 100191, China
Published: December 2020

The Mn3Sn1-xCoxC1.1 compounds are synthesized by a solid-state reaction method. The effects of Co doping on the magnetic properties, phase transition and entropy change are investigated in Mn3Sn1-xCoxC1.1 compounds. The Curie temperature first decreases from 283 K to 212 K (Mn3Sn0.9Co0.1C1.1) with increasing the Co concentration, and then increases to 332 K (Mn3Sn0.2Co0.8C1.1) with further increasing the Co concentration in Mn3Sn1-xCoxC1.1. The first-order transition of Mn3Sn1-xCoxC1.1 gradually changes into the second-order transition, in the mean time, the entropy change decreases and the phase transition region broadens from 9 K to 300 K with increasing the Co content. Both the magnetic entropy change and broadening the transition temperature span can influence the relative cooling power R. Finally we obtain the large R=103 J/kg (H=1.6 MA/m) in Mn3Sn0.8Co0.2C1.1, which could be used as the room-temperature magnetic refrigerant materials.
Micromagnetic simulation and analysis of Nd2Fe14B/Fe65Co35 magnetic bilayered thin films with different orientations of the easy axis
Authors: Peng Yi  , Zhao Guo-Ping  , Wu Shao-Quan  , Si Wen-Jing  , Wan Xiu-Lin  ,   College of Physics and Electronic Engineering, Sichuan Normal University, Chengdu 610068, China
Published: December 2020

The hysteresis loops, angular distribution, nucleation field, coercivity and energy product are calculated by three-dimensional micromagnetic method for Nd2Fe14B/Fe65Co35 bilayers with a deviation of the easy axis, and the results are compared with the experimental results. The results show that obvious nucleation can be observed only when the β between the easy axis and the applied field is equal to 0°, and the nucleation field and the coercivity decrease as the thickness of the soft phase Ls increases. The remanence decreases and the squareness of the hysteresis loop weakens as β increases, leading to the decrease of the energy product while the largest maximum energy product (561.61 kJ/m3) occurs at Ls=1 nm and β=0°. The shapes of the hysteresis loops, the remanence and the coercivity obtained from calculations and experiments are close to each other.
Noise analysis of hard X-ray differential phasecontrast imaging
Authors: Huang Jian-Heng  , Du Yang  , Lei Yao-Hu  , Liu Xin  , Guo Jin-Chuan  , Niu Han-Ben  ,   Key Laboratory of Optoelectronic Devices and Systems of Guangdong Province, Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China
Published: December 2020

Quantum noise is an important factor influencing the quality of the images obtained by X-ray phase contrast imaging because it induces a random fluctuation on the intensity. In this paper, a method is reported to analyze the noise characteristics of hard X-ray differential phase contrast imaging, and the relationship between the quantum noise and images is determined by numerical simulation. The results show that the mean square deviations of the refractive and scattering images are inversely proportional to the visibility of moir fringe. That is to say, the higher visibility of moir fringe leads to the lower mean square deviations of the refractive and scattering images. Therefore, in the case of ensuring an enough X-ray detection efficiency, the improvement in the visibility of moir fringe will be beneficial to obtaining high-quality phase contrast images and the effective reduction of X-ray exposure dose.
Asymptotic solution to the generalized Duffing equation for disturbed oscillator in stochastic resonance
Authors: Han Xiang-Lin  , Lin Wan-Tao  , Xu Yong-Hong  , Mo Jia-Qi  ,   Departmentt of Mathematics, Huzhou Teachers College, Huzhou 313000, China;,   State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamic, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China;,   Department of Mathematics & Physics, Bengbu College, Bengbu 233030, China;,   Department of Mathematics, Anhui Normal University, Wuhu 241003, China
Published: December 2020

A class of nonlinear generalized Duffing equation for disturbed oscillator is considered. Firstly, the typical Duffing equation is solved. Then approximate solutions to the nonlinear Duffing equation for disturbed oscillators in stochastic resonance is obtained using the generalized functional variation principle, and the uniform validity is proved.
Finite-time stability for switched singular systems
Authors: Zhang Yao-Li  , Wu Bao-Wei  , Wang Yue-E  , Han Xiao-Xia  ,   College of mathematics and Information Science, Shaanxi Normal University, Xi'an 710062, China
Published: December 2020

In this paper, finite-time stability and stabilization of switched singular systems are studied. Firstly, we discuss the solvability condition of the switched singular system and introduce the concepts of finite-time stability and finite-time boundness. Secondly, using the mode-dependent average dwell time method and the Lyapunov function method, we provide sufficient conditions to guarantee that the switched singular system is regular, impulse free, and finite-time stable or finite-time bounded. Then, we design the state feedback controllers to ensure that a closed-loop system is finite-time stable and finite-time bounded with a present H disturbance attenuation level . Finally, numerical examples are given to verify the efficiency of the proposed theory.
Quantum Fisher information and spin squeezing in the interaction system of light and matter
Authors: Chang Feng  , Wang Xiao-Qian  , Gai Yong-Jie  , Yan Dong  , Song Li-Jun  ,   Department of Physics, Changchun University of Science and Technology, Changchun 130022, China;,   Department of Physics, Changchun University, Changchun 130022, China
Published: December 2020

Fisher information is an important concept in estimation theory, which has recently been found closely related with the criteria of the entanglement in quantum information. Under the condition of non-rotating wave approximation, the classical phase space of the Dicke model displays chaotic dynamic properties. This paper studies the quantum Fisher information and the dynamic properties of spin squeezing in the interaction system of light and matter described in the Dicke model. Results reveal that, in the short-time instant state, wherever the initial state is, in a regular region or a chaotic region, the system displays entanglement; but in the long-time stable state, when the initial state is in the regular region, the system entanglement disappears, however, when the initial state is in the chaotic region, the system is always entangled. Compared with the spin-squeezing dynamic properties of the system, Fisher information is found to be able to effectively characterize quantum chaos. On further examination on the dynamic evolvement properties of the density matrix and purity of the system when in the regular and chaotic regions, we find that chaos gives rise to decoherence of the system, showing that quantum information become more sensitive to chaos.
Steady-state analysis of a tristable system driven by a correlated multiplicative and an additive colored noises
Authors: Shi Pei-Ming  , Li Pei  , Han Dong-Ying  ,   College of electrical engineering, Yanshan University, Qinhuangdao 066004, China;,   College of Vehicles and Energy, Yanshan University, Qinhuangdao 066004, China
Published: December 2020

The steady-state problems of a tristable system are studied under the action of color correlated multiplicative and additive colored noise. Firstly, the expression of the steady-state probability density function is derived based on the uniform colored noise approximation, and then the change regulation of the steady-state probability density function is analyzed with the change of the strength and relevance of multiplicative noise and additive noise. Results show that the non-equilibrium phase transition of the system can be induced by the correlation strength and time of additive noise and multiplicative noise as well as the additive noise strength.
Chaotic characteristic study of GIC in buried steel oil pipeline
Authors: Liang Zhi-Shan  , Wang Peng  , Hu Li-Hua  , Zhang Ju-Qiu  ,   College of Geophysics and Information Engineering, China University of Petroleum(Beijing), Beijing 102249, China
Published: December 2020

Variations of the geomagnetic field drive geomagnetically induced currents (GIC) in the buried steel pipelines, which may contribute to the pipeline corrosion and the pipeline network interfered by the solar wind and magnetic storm, are actually a complex nonlinear dynamical system. This paper shows that the induced current in the buried steel pipeline system has chaotic characteristics. To prove this, we first establish the lump-constant geomagnetic interference model based on the distributed source transmission line theory. Then we analyze this model by using Melnikov method and find out the condition under which the chaotic phenomenon will occur. In order to get a sufficient proof to validate the existence of chaos in pipelines, we also obtain the actual GIC time series by utilizing the measured data provided by national geomagnetic observatory and analyze its chaotic characteristics using multiple chaotic criteria. Analysis results of both the model and the measured data indicate that the pipeline's GICs have chaotic characteristics. This provides a theoretical basis for protecting pipeline from the effects of space weather.
Escape rates of particles in Stadium mesoscopic devices
Authors: Shen Zhi-Peng  , Zhang Yan-Hui  , Cai Xiang-Ji  , Zhao Guo-Peng  , Zhang Qiu-Ju  ,   College of Physics and Electronics, Shandong Normal University, Jinan 250014, China;,   College of Physics, Shandong University, Jinan 250100, China
Published: December 2020

We have studied the chaotic escape of particles in a two-dimensional weakly opened mesoscopic components of the Bunimovich Stadium devices. Within the framework of classical statistics, we get the change of the fractal dimensions and the escape rates in several parameters of the device, such as the opening width, the arc radius and the cavity length. We first find the good agreement between the fractal dimensions and the escape rates, and reveal that the exponential law of escape is affected by the shape of device. We count and fit the relationship between the escape rates and the wave numbers of the particles. As is shown in the numerical results, the relation between the escape rates and the wave numbers is a quadratic function, but the escape rates are not strictly linearly varied with the change of the energy. Furthermore, we analyze the influence of diffraction at the lead opening on the escape of the particles. Numerical results show that the diffraction effect makes the escape rates increase, and the evolution of the number of particles no longer obeys the law of exponential decay in a short time, but observes it again in a long time.