bluuebunny/crossref_metadata_2025 huggingface dataset:
Software realization of optical information hiding system based on phase-shifting interferometry
Authors: Fan De-Sheng  , Meng Xiang-Feng  , Yang Xiu-Lun  , Wang Yu-Rong  , Peng Xiang  , He Wen-Qi  ,   Department of Optics, School of Information Science and Engineering and Shandong Provincial Key Laboratory of Laser Technology and Application, Shandong University, Jinan 250100, China;,   College of Optoelectronics Engineering, Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, Shenzhen University, Shenzhen 518060, China
Published: December 2020

Combining the techniques of double random phase encoding and phase-shifting interferometry, an information hiding system is proposed, in which the information to be hidden can be encrypted into multiple interferograms. By choosing the appropriate weighting factor, the interferograms can be embedded in the host image. The secrete information can be successfully extracted and decrypted by special phase-shifting reconstruction formula and inverse Fresnel diffraction transform. A software of information hiding system is designed by mixed programming between Visual C++ and Matlab based in the Matcom software environments. By testing the software interface, the designed software can successfully realize the main functions, such as image reading and displaying, input of basis geometrical parameters, information encrypting and embedding, information extracting, decrypting, robustness testing, etc..
Parameter extraction for photovoltaic module based on Lambert W function
Authors: Wang Yu-Ling  , Sun Yi-Ze  , Peng Le-Le  , Xu Yang  ,   The College of Mechanical Engineering, Donghua University, Shanghai 201620, China
Published: December 2020

In order to solve the problems that engineering model of photovoltaic array has low accuracy (within 5%) and five-parameter model has more parameters which are difficult to obtain, a new method of parameters extraction is presented in this paper. This method is first to use Lambert W function to obtain the analytic expression for photovoltaic module, then to use polynomial curve fitting method to obtain the current-voltage relationship of PV module, and finally to use the subsection integral method to obtain the value of parameters for photovoltaic module. The proposed method shows that the accuracy is within 0.5%. Compared with conductivity method and pattern search method, this method not only has intuitive features but also is easy to use. Furthermore, the obtained photovoltaic module parameters possess smaller errors (within 0.1%).
Theoretical study of level structure and transitions of configurations 3d94s2 3d94s4p, 3d94p2 for Nb XIII
Authors: Mu Zhi-Dong  , Wei Qi-Ying  ,   School of Science, China University of Mining Science and Technology, Xuzhou 221008, China
Published: December 2020

Fine-structure energy levels of two-electron excitation configurations 3d94s2, 3d94s4p, 3d94p2 are calculated by Hartree-Fock method, which includes the configuration interaction, relativistic correction and approximate Breit correction, for copper-like Nb XIII. More accurate levels are obtained by the least-square-fit technique. The wavelengths and transition probabilities of 3d94s4p-3d104s, 3d94s2-3d104p, 3d94p2-3d104p, 3d94s4p-3d94s2 transition array are obtained, and some unknown results are predicted. Computing research shows that the 40.92 nm line should belong to 3d94s(1D)4p2F7/2-3d9(2D)4s2 2D5/2 transition, but not to the 3d94s(1D)4p4D7/2-3d9(2D)4s2 2D5/2 transition, and the upper term level should be 2F7/2, but not 4D7/2.
Polarization switching dynamics of vertical-cavity surface-emitting laser subject to negative optoelectronic feedback
Authors: Wang Xiao-Fa  ,   School of Optoelectronics Engineering, Chongqing University of Posts and Telecommunications, Chongqing 400065, China
Published: December 2020

Using the extended spin-flip model, we theoretically investigate the polarization switching dynamics of a vertical-cavity surface-emitting laser subject to negative optoelectronic feedback. The results show that when the laser operates at two different the spin-flip rates, the feedback intensity and delay time have great influence on polarization switching dynamics. At a slow spin-flip rate, with the increase of feedback intensity, switching current increases linearly, that the X polarization mode is compressed is contrary to the reported results based on isotropic optical feedback. The reason may be due to the fact that the negative optoelectronic feedback improves the X polarization mode threshold; the effect of delay time will vary with feedback intensity. At a fast spin-flip rate, the effect of feedback strength is different from at a slow spin-flip rate, the switching point current undergoes a process in which the current increases first and then decreases gradually, the switching point current is more sensitively dependent on the feedback strength; while effect of the delay time is similar to that at a slow spin-flip rate. In addition, we find that the spontaneous emission noise has a great influence on polarization switching dynamics.
Investigation on the characteristics of micro/nanofiber Bragg grating for refractive index sensing
Authors: Liu Ying-Gang  , Che Fu-Long  , Jia Zhen-An  , Fu Hai-Wei  , Wang Hong-Liang  , Shao Min  ,   Shaanxi Key Laboratory of Photoelectric Sensing Logging, Xi’an Shiyou University, Xi’an 710065, China
Published: December 2020

Using the fiber Bragg grating equation and the functional relation of the fundamental effective mode refractive index (RI), the mathematical model of the wavelength shift and the relational function of wavelength sensitivity are established, when the reflected wavelength of the micro/nanofiber Bragg grating (MNFBG) changes with ambient RI and the fiber radius. The theoretical relationship demonstrates that the variation of MNFBG reflected wavelengths is dependent on the change of effective RI with fiber radius and ambient RI. Meanwhile, we also study the variation of effective RI and its sensitivity in detail. The results show that the effective RI nonlinearly decreases with fiber-core radius and ambient refractive index decreasing, and its sensitivity increases as the ambient refractive index increases, and the sensitivity, linearity and the linear response range increase with the decrease of the fiber radius. For a fiber radius of 0.5 μm, by simulating the curves of the effective index versus ambient RI in the index ranges of 1.20-1.30 and 1.33-1.43 respectively, the values of wavelength sensitivity of 477.33 nm/RIU and 856.30 nm/RIU and the values of high linearity of 99.2% and 99.7% are obtained, which not only verifies the analysis conclusions and the measurement program for RI sensing with MNFBG, but also supplies references for the RI sensor design, optimization and the application.
Wavelet analysis of passive temperature in a turbulent cylinder wake(Retracted Article)
Authors: Ge Yang-Zhen  , Xu Min-Yi  , Mi Jian-Chun  ,   State Key Laboratory of Turbulence and Complex Systems, Peking University, Beijing 100871, China
Published: December 2020

A wavelet multi-resolution technique is applied to analysing the temperature field simultaneously obtained by a rake of 16 cold-wires in the turbulent near-wake of a slightly heated circular cylinder with a diameter of d = 12.7 mm in a range of x/d from 3 to 20, where x is the downstream distance from the cylinder axis. This technique enables us to decompose the fluctuating temperature field into a number of wavelet components based on different characteristic frequency bandwidths or scales, which are representative of the temperature fields of different scales. The turbulent mixing characteristics of various fluctuating scales are examined in terms of instantaneous temperature contours of each wavelet component. The flow structures and intermittent processing of various scales are visualized. The streamwise evolutions of temperature variance of various scales suggest that the intermediate-scale structures make larger contribution to the total temperature than the large- and small-scale structures. The wavelet auto-correlation function indicates that the large- and intermediate-scale structures display larger correlation and the wavelet component of higher frequency loses coherence quickly.
Experimental study of friction effect under impact loading
Authors: Jiang Guo-Ping  , Hao Hong  , Zeng Chun-Hang  , Hao Yi-Fei  , Wu Ru-Jun  , Liu Ji-Chao  ,   Earthquake Engineering Research Test Center, Guangzhou University, Guangzhou 510405, China;,   Guang Zhou Shi Sheng Te CO., LTD, Guangzhou 510405, China
Published: December 2020

When testing impact dynamics of concrete, usually a variety of kinetic effects can be seen, such as the axial and lateral inertial confinement effects, the effects of stress wave propagation and the final friction effects, etc. Some of these are the material is nature itself such as the size effect, some are experimental errors, etc., but all the dynamic effects, may enter the final test results so that unnecessary errors or even wrong values may be brought into experiments. Due to the mechanism of friction effect, we have designed three different sizes of specimen for SHPB test. The quantitative values of the friction effect are obtained. The DIF is corrected, which is the basis for concrete impact engineering design.
Study on proton irradiation induced defects in GaN thick film
Authors: Zhang Ming-Lan  , Yang Rui-Xia  , Li Zhuo-Xin  , Cao Xing-Zhong  , Wang Bao-Yi  , Wang Xiao-Hui  ,   Colleage of Information Engineering, Hebei University of Technology, Tianjin 300401, China;,   Key Laboratory of Semiconductor Materials Science Institute, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China;,   Key Laboratory of Nuclear Analysis Techniques, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

Proton-irradiation-induced defects threaten seriously the stable performance of GaN-based devices in harsh environments, such as outer space. It is therefore urgent to understand the behaviors of proton-irradiation-induced defects for improving the radiation tolerance of GaN-based devices. Positron annihilation spectroscopy (PAS) has been used to study proton-induced defects in GaN grown by HVPE. The result shows that VGa is the main defects and no (VGaVN) or (VGaVN)2 is formed in 5 MeV proton-irradiated GaN. Photoluminescence (PL) spectrum is carried out at 10K. After irradiation, the band edge shows a blue-shift, but the donor-acceptor pair (DAP) emission band and its LO-phonon replicas is kept at the original position. The intensity of yellow luminescence (YL) band is decreased, which means that the origin of YL band has no relation with VGa. The increased FWHM of GaN (0002) peak in proton-irradiated GaN indicates a degradation of crystal quality.
Molecular dynamics simulation of the wetting behavior of Pb droplet on Ni substrate
Authors: Qiu Feng  , Wang Meng  , Zhou Hua-Guang  , Zheng Xuan  , Lin Xin  , Huang Wei-Dong  ,   State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072, China
Published: December 2020

Molecular dynamics simulation is performed to investigate the wetting behaviors of Pb droplet on Ni(100), Ni(110) and Ni(111) substrates. It has been shown that the wetting behavior of precursor film is isotropic for Pb droplet on Ni(100) and Ni(111) substrates, but anisotropic for Pb droplet on Ni(110) substrate. The demonstrated anisotropy is attributed to the differences in diffusion mechanism and rate along different crystal orientations for Pb atoms with corresponding anisotropic structure of the crystal lattice on Ni(110) substrate. The spreading dynamics of precursor film on different lattice surfaces are also investigated, which shows that there is no surface alloy formed for Pb droplet on Ni(111) surface and the spreading dynamics can be described by R2 t, but surface alloy forms for Pb droplet on Ni(100) and Ni(110) surface and the spreading dynamics satisfies R4 t, at the same time the spreading rate of droplet on Ni(100) is higher than that of Ni(110) substrate.
Bell-type inequality and tripartite nonlocality in three-qubit GHZ-class states
Authors: Zhao Jia-Qiang  , Cao Lian-Zhen  , Lu Huai-Xin  , Wang Xiao-Qin  ,   Shandong Provincial Key Laboratory of Multi-photon Entanglement and Manipulation, Department of Physics and Optoelectronic Engineering, WeifangUniversity, Weifang 261061, China
Published: December 2020

In this paper, we theoretically study the relation between concurrence and nonlocality depicted by Bell-type inequality violation of quantum mechanics prediction versus local realism prediction for the GHZ (Greenberger -Horne-Zeilinger) class states. Analytical expressions of concurrence, violations of the Mermin inequality and the Svetlichny inequality are obtained. Through numerical calculations, the relationship between entanglement and nonlocality of GHZ-class states is discussed. Our results show that the concurrence is consistent with the degree of nonlocality described by violations of the two Bell-type inequalities of GHZ-class states. The Bell operator and its parameters can obviously reveal the nonlocal features of quantum states.
Multi-configuration time dependent Hartree Fock method in three different representations
Authors: Li Wen-Liang  , Zhang Ji  , Yao Hong-Bin  ,   Xinjiang Institute of Engineering, Urumqi 830091, China
Published: December 2020

As a powerful tool to deal with multi-electron dynamics in strong laser field, multi-configuration time-dependent Hartree Fock (MCTDHF) method has attracted great attention. In this paper, the strategy of the implement of the MCTDHF theory is illustrated in the paper in detail. We develop three types of Fortran source soft packages based on three different bases to study correlated dynamics of atoms and molecules in strong laser field. The calculated soft-packages based on the theory are introduced in detail. The calculations are performed by using the soft-package. The prospect of the MCTDHF approach to simulating the multi-electron dynamics in strong laser field are also presented.
Jet splitting after bubble breakup at the free surface
Authors: Ni Bao-Yu  , Li Shuai  , Zhang A-Man  ,   School of Shipbuilding Engineering, Harbin Engineering University, Harbin 150001, China
Published: December 2020

Under potential flow assumption, a numerical method is established to simulate the nonlinear movement of the free surface after the breakup of a bubble, with taking the surface tension and viscous into consideration. A method to handle the splitting of the jet or drop is put forward. Besides, an experiment of rising bubble bursting at the free surface is conducted, and the numerical result is in good agreement with the experimental result. In order to study the mechanism and law of the free surface movement after bubble breakup, the dynamic behavior of different sizes of bubble breakup is studied with the program developed, including the jet from the bottom of the bubble, the splitting of the jet or drop and so on. The variation law of the size and time of the first splitting drop, and the maximum velocity of the jet is studied and summarized. Finally, the influences of Reynolds number and Weber number on the free surface after bubble breakup are also analyzed.
Molecular dynamics investigation of thermal stability of Pt-Au core-shell nanoparticle
Authors: Wang Zhi-Gang  , Huang Rao  , Wen Yu-Hua  ,   College of Physics and Electronic Engineering, Leshan Teachers’ College, Leshan 614004, China;,   School of Physics and Mechanical and Electrical Engineering, Xiamen University, Xiamen 361005, China
Published: December 2020

In this paper, we have examined the thermal stability of Pt-Au core-shell nanoparticle by using molecular dynamics simulations with embedded-atom potential. The results show that the melting point of Pt-Au core-shell nanoparticle is significantly higher than that of pure Au one but lower than that of Pt one. By the analyses of Lindemann index, it is discovered that the melting first occurs in Au shell, then spreads into interior, finally the overall melting of Pt core appears. The temperature range of melting is much broader for Pt-Au core-shell nanoparticle than for Au and Pt nanoparticles. Moreover, Pt-Au core-shell nanoparticle exhibits a distinct two-stage melting during continuous heating, and the structure of solid (core)-liquid (shell) coexistence has been observed between two meltings.
Analysis of the direction of information transfer of Lorenz system and Walker circulation with transfer entropy
Authors: Zhang Zhi-Sen  , Gong Zhi-Qiang  , Zhi Rong  ,   Department of Atmospheric and Sciences, Lanzhou University, Lanzhou 730000, China;,   National Climate Center, Beijing 100081, China
Published: December 2020

By the transfer entropy method, in this article we analyze the transfer of information between x, y, z component of Lorenz system and Walker circulation with temperature difference and vertical velocity. It is found that y is the information source and x is the information sink between x and y component of Lorenz system, also y is the information source and z is the information sink between x and z component. But the direction of information transfer depends on the control parameter r between x and z component, even if the direction of information transfer between x, y and z component of Lorenz system does not vary when the initial value changes. In western Pacific, the information transfers from the temperature difference to the vertical velocity, while the information transfers from the vertical velocity to the temperature difference in the eastern equatorial Pacific, which is consistent with the physical mechanism of Walker circulation. And land-sea thermal plays an important role in the information transfer between temperature difference and vertical velocity. In winter, the information transfer between temperature difference and vertical velocity is strongest, in summer and autumn it is weaker, and in spring it is weakest, which may be the reasons of spring predictability barrier. These results suggest that transfer entropy is proved to be an effective method and tool of measuring the transfer direction of the kinetic system information, and has broad application prospects in the field of meteorology.
Try to use Lyapunov exponent to discuss the abrupt climate change and its precursory signals
Authors: Wu Hao  , Hou Wei  , Wang Wen-Xiang  , Yan Peng-Cheng  ,   College of Physical Science and Technology, Yangzhou University, Yangzhou 225002, China;,   National Climate Center, Beijing 100081, China;,   College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070, China
Published: December 2020

Lyapunov exponent is an important physical quantity indicating a system is in regular motion or in chaotic motion. In view of this, in this paper, we use the Lyapunov exponent to study the chaotic properties of the system, and the mutations in climate. The results show that the Lyapunov exponent is a reliable mutation detection method. For the ideal sequence or actual atmosphere sequence the method can be used to accurately find out the mutation position; the predictability of nonlinear local Lyapunov exponent is used to evidence the reliability of the early warning signals of abrupt climate change based on the phenomenon of critical slowing down, through calculating the largest Lyapunov exponent of each time the system intrinsic properties can be reflected and the chaos characteristics can be studied, thereby providing a theoretical basis for the wide applications of the present method in real observation data.
Thermally controlled terahertz metamaterial modulator based on phase transition of VO2 thin film
Authors: Liu Zhi-Qiang  , Chang Sheng-Jiang  , Wang Xiao-Lei  , Fan Fei  , Li Wei  ,   Institute of Modern Optics, Nankai University, Key Laboratory of Optical Information Science and Technology, Ministry of Education, Tianjin 300071, China
Published: December 2020

Utilizing insulator-metal phase transition of vanadium dioxide thin film, we propose a thermally controlled terahertz modulator based on metamaterial, and research the transmission characteristics and temperature tunable characteristics of phase transition in metamaterials in THz wave band. While the incident THz wave is of horizontal polarization or vertical polarization, two independent pass bands are generated near 1 THz. The center frequencies of the two pass bands are 1.3 THz and 1.7 THz, the bandwidths of them are 0.2 THz and 0.35 THz. In addition, when temperature rises from 40℃ to 80℃, the transmissions of the two pass bands drop apparently, especially at phase transition temperature of 68℃. For the two polarization states, the modulation depths achieve 60% or more, which is the great function of a modulator.
Vibro-acoustic characteristics of shear deformable stiffened laminated panels in mean flow
Authors: Jin Ye-Qing  , Yao Xiong-Liang  , Pang Fu-Zhen  , Zhang A-Man  ,   College of Shipbuilding Engineering, Harbin Engineering University, Harbin 150001, China
Published: December 2020

A theoretical model is developed to investigate vibro-acoustic characteristics of shear deformable periodic stiffened laminated composite panels in mean flow, based on the first-order shear deformation theory (FSDT). The convected wave equation and boundary condition are used to account for the exact coupling effect between mean flow and laminated panel. Stiffeners interact with the laminated panel through both the normal line forces and torsional moments. Analytic formulations for the transverse displacement spectra and sound pressure level (SPL) are yielded by employing the Fourier wavenumber transform and the stationary phase method. The model is validated by comparing with existing public data. Excellent agreement is obtained. Numerical results show that the effects of shear deformation and torsional motion of the stiffeners cannot be ignored in high frequency range. SPL can be reduced by increasing the speed of mean flow; it is possible to avoid SPL peaks by altering the thickness and stiffener spacing.
Fracture behavior of TiN coating under nanoindentation and nanoscratch test
Authors: An Tao  , Wen Mao  , Tian Hong-Wei  , Wang Li-Li  , Song Li-Jun  , Zheng Wei-Tao  ,   College of Science, Changchun University, Changchun 130022, China;,   Department of Materials Science, Jilin University, Changchun 130012, China
Published: December 2020

A TiN coating with (111) and (222) preferred orientations was deposited on a Si(111) substrate by using reactive magnetron sputtering a Ti target. The deformation mechanism and fracture behavior of the coating are determined by nanoindentation and nanocratch experiments. The morphologies of the indentations and nanoscratch marks are revealed by scanning electron microscopy, in situ atomic force microscopy and optical microscopy. Local cracks of TiN appear around the indentation marks when the peak indentation displacement is below the critical value of 1000 nm. As the peak displacement exceeds 1000 nm, an interfacial fracture between the TiN coating and the Si(111) substrate is observed. Nonoscratch tests show that interfacial fractures are also induced by nanoscratch experiments under peak loads of 100 and 200 mN. The critical loads for interfacial fractures under 100 and 200 mN peak loads are equal to those under nanoindentation tests.
Noncollinear magnetic order and spin-orbit coupling effect in (FeCr)n alloying clusters
Authors: Zhang Bao-Long  , Wang Dong-Hong  , Yang Zhi  , Liu Rui-Ping  , Li Xiu-Yan  ,   Key Laboratory of Advanced Transducers and Intelligent Control System, Ministry of Education, College of Physics and Optoelectronics, Taiyuan University of Technology, Taiyuan 030024, China
Published: December 2020

Using density functional theory, the structures, stabilities and magnetic properties of (FeCr)n (n≤ 6) alloying clusters are systematically investigated. For smaller clusters with n≤3, the results show that the ground-state system possesses collinear antiferromagnetic order. For n≥4 cases, however, the ground-state cluster has noncollinear magnetic order. Therefore, there is a collinear-to-noncollinear magnetic transition at n=4 in (FeCr)n systems. In addition, although the spin-orbit coupling effect of 3d transition metal atom is often weak, the results indicate that the orbital magnetic moments of some certain clusters are significant and important. Finally, the chemical bond of noncollinear magnetic clusters and the physical origin of the magnetic transition are analyzed.
A comparative study of different potentials for molecular dynamics simulations of melting process of silicon
Authors: Zhou Nai-Gen  , Hu Qiu-Fa  , Xu Wen-Xiang  , Li Ke  , Zhou Lang  ,   School of Materials Science and Engineering, Nanchang University, Nanchang 330031, China
Published: December 2020

Molecular dynamic simulations of bulk melting and surface melting of Si are carried out. The atomic interactions in Si are calculated by stillinger-weber (SW), modified embedded-atom method (MEAM), Tersoff and highly optimized empirical potential (HOEP) potentials respectively. The results show that the four potentials could exhibit the fundamental laws of Si, such as thermal expansion, melting at high temperature, endothermic and volume shrinkage in melting process. However, the detailed analyses demonstrate that the Tersoff and MEAM potentials are best to describe the melting and crystal growth of Si, SW potential is the next. The HOEP potential is even unsuitable for describing the melting and crystal growth of Si.
Compression behavior of nanocrystalline nickel at 77 K
Authors: Ma Guo-Liang  , Liu Hai  , Wang Hao  , Li Xing-Ji  , Yang Jian-Qun  , He Shi-Yu  ,   Science and Technology on Material Performance Evaluating in Space Environment Laboratory, Harbin Institute of Technology, Harbin 150001, China
Published: December 2020

In this paper, compression test is carried on electrodeposited nano-crystalline (NC) Ni at 77 K. The results show that the NC Ni has extremely high compressive strengths: around 2.5 GPa at room temperature (RT), 3.5 GPa at 77 K, and moderate plasticity with 0.1 fracture strain at RT, 0.05 at 77 K. The strain rate sensitivity m and activation volume v are calculated, and scanning election microscope and high-resolution transmission election microscope are used to verify the deformation mechanism. Analysis indicates that the dislocation interaction with grain boundary (GB) dominates the deformation of NC Ni both at 77 K and RT. Based on the calculated values of m and v, the deformation process is described by considering the intrinsic dislocation of GB bowing out and expanding towards opposite GB in the inner grain dislocation-free zone. And the mechanism is studied in the residual dislocation parts affecting the increase of strain compatibility and the decrease of stress concentration. It is indicated that the difference in compression property between at RT and 77 K is relatated to grain boundary-dislocation coordination mechanism and relation between residual dislocation motion and temperature.
The study of Raman spectrum, distortion of lattice and spin reorientation phase transition on Pr doped DyFeO3 system
Authors: Liu Ming  , Cao Shi-Xun  , Yuan Shu-Juan  , Kang Bao-Juan  , Lu Bo  , Zhang Jin-Cang  ,   Department of Physics, Shanghai University, Shanghai 200444, China;,   Laboratory for Microstructures, Shanghai University, Shanghai 200444, China
Published: December 2020

Pr doped rare-earth orthoferrites DyFeO3 is synthesized by solid state reaction. X-ray diffraction shows that the lattice parameters of Dy1-xPrxFeO3increase and distortion of lattice decreases with Pr content x increasing. Raman spectroscopy reveals that the change of effective mass (meff) [meff=xmPr+(1-x)mDy] together with lattice structure change results in the shift of vibration modes. With the increase of Pr content, Raman modes of wave number less than 200 cm-1 remain constant, but the modes of wave number greater than 200 cm-1 decrease with Pr content increasing (except the mode B3u near 420 cm-1). The weak ferromagnetic ordering, created by Dzyaloshinsky-Moriya interaction, is reduced with doping level increasing. The interaction of rare earth ions with Fe3+ ion, together with the change of lattice distortion, results in the increasing of spin reorientation phase transition temperature when xx increasing to over 0.3.
Preparation and influencing factors of graphene-silver nanocomposites
Authors: Fan Bing-Bing  , Guo Huan-Huan  , Li Wen  , Jia Yu  , Zhang Rui  ,   College of Material Science and Engineering, Zhengzhou University, Zhengzhou 450001, China;,   Department of Physics Engineering, Zhengzhou University, Zhengzhou 450001, China;,   Zhengzhou Institute of Aeronautical Industry Management, Zhengzhou 450053, China
Published: December 2020

Graphene/silver nanocomposites are synthesized in the presence of sodium hydroxide, with graphene oxide and AgNO3 used as the raw materials. X-ray diffraction, Fourier transform infrared spectroscopy (FT-IR), and transmission electronic electron microscope, UV-vis spectrophotometer are used to characterize the obtained composites. Results indicate that the graphene oxide is partically reduced to graphene sheets, silver ions are reduced to silver nanoparticles and distributed on the graphene sheets uniformly. The action temperature, quantity of silver nitrate, adding order of NaOH and the way of mixing precusors have an influence on the silver size and particulate size distribution. The size distribution of Ag nanoparticles is centred at 12 nm under a suitable number of silver ions.
A wideband low RCS reflection screen based on artificial magnetic conductor orthogonal array
Authors: Zhao Yi  , Cao Xiang-Yu  , Gao Jun  , Yao Xu  , Ma Jia-Jun  , Li Si-Jia  , Yang Huan-Huan  ,   School of Information and Navigation of AFEU, Xi’an 710077, China
Published: December 2020

Based on the electromagnetic properties of complementary split ring resonator (CSRR), a novel artificial magnetic conductor (AMC), CSRR-AMC, is designed. The comparison of the reflection phase with square patch AMC reveals its features of miniaturization and multiband in-phase reflection, under X- and Y-polarized normal incident waves, respectively. Inspired by the reflection phase difference under different incident conditions, we have designed a wideband low rader cross-section (RCS) reflection screen with a single CSRR-AMC structure. The CSRR-AMC arrays are orthogonally positioned and the backscattering energy is reduced as a result of phase cancellation. Measured results demonstrate that -10dB RCS reduction is achieved in a wide frequency range of 7.38–10.47 GHz and the relative bandwidth is 34.6%, providing a new method for the design of wideband low scattering structure.
An overview of the method of high-precision measuring the aperture diaphragn area
Authors: Chen Xiang-Zi  , Fang Wei  , Wang Yu-Peng  , Yang Zhen-Ling  , Quan Xiang-Qian  ,   Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China;,   University of Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

Some radiometric and photometric measurements need high accuracy knowledge of the area of the aperture. So the accurate knowledge of the area of the limiting aperture is very important. There are two types of methods to measure the aperture areas. Type-one contains contract method, and no-contract method, and type-two contains geometrical method and effective area method. In this paper we first describe all the methods briefly, then emphatically explain the no-contract method, geometrical method and effective area method. Finally, a comparison of measurement accuracy, degree of difficulty in measurement, and equipment cost among different methods, indicates that the geometric method and the effective area method are very promising. In order to improve the uncertainty of the measurement, more stable laser and accurate translation stage are needed.
Study of ignition process of boron particle with considering Stefan flow effects
Authors: Fang Chuan-Bo  , Xia Zhi-Xun  , Xiao Yun-Lei  , Hu Jian-Xin  , Liu Dao-Ping  ,   Science and Technology on Scramjet Laboratory, National University of Defense Technology, Changsha 410073, China;,   College of Aerospace and Material Engineering, National University of Defense Technology, Changsha 410073, China
Published: December 2020

A one-dimensional model about the ignition process of boron particle in boron-based propellant ducted rocket is systemically investigated. The gas flow around the boron particle, the heat transfer and the mass transfer between the boron particle and the surrounding are included in the model. And the effects of Stefan flow are also proposed. The changing regularities of important parameters in the two typical cases, viz., the successful ignition case and the degenerate ignition case are studied in detail. And their reasons are analyzed. The result shows that both the evaporation of the liquid boric oxide layer and the oxidation of the boron are remarkably accelerated as the result of the self-heating exothermic oxidation in the successful ignition case, and the mass fraction profiles of the oxygen gas and those of the B2O3 gas also dramatically change in that case. However, both the mass flux of the evaporation of the liquid boric oxide layer and that of the consumption of the oxygen gas are relatively small, and both of them tend to be nearly constant in the degenerate ignition case. The mass fraction profile of the oxygen gas and that of the B2O3 gas change little in the degenerate ignition case. In the two typical cases, Stefan flow on the boron particle surface undergoes the change of flow direction, viz., Stefan flow initially comes from the surrounding and then it flows from the particle surface to the surrounding.
A construction method of biorthogonal heart sound wavelet
Authors: Cheng Xie-Feng  , Zhang Zheng  ,   College of Electronic Science and Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210003, China
Published: December 2020

In order to improve the performance of the wavelet analysis in the process of the heart sound signals, in this paper, we construct a wavelet basis which is exclusively used for processing the heart sound signals on the basis of wavelet theory construction. Firstly, we propose a general method of constructing a compactly supported biorthogonal wavelet which has even length filter banks, Secondly, according to the characteristics of heart sound signals, we discuss the structure principle of heart sound wavelet and a synthesis model of heart sound signals based on the heart sound wavelets. Finally, we construct the heart sound wavelet on the basis. In order to highlight the advanced nature and practical application of heart sound wavelet in processing heart sound signals, the theory and numerical simulation of heart sound wavelet are analyzed more comprehensively. Experimental results show that compared with commonly using the db and bior series wavelets, using the heart sound wavelet to process the heart sound signals can obtain good denoising effect, accurate classified information about heart sound and low reconstruction error rate. So the heart sound wavelet provides a new method of deep studying of heart sound feature extraction and identification and has a positive significance in describing the details of the individual characteristics of the heart sounds. The paper designs a method of the special wavelet which is based on the application object, which provides a new approach to the selection of wavelet basis in engineering applications.
Cross polarization effects of vortex beam in reflection
Authors: Zhang Jin  , Zhou Xin-Xing  , Luo Hai-Lu  , Wen Shuang-Chun  ,   Key Laboratory for Micro-/Nano-Opto-electronic Devices of Ministry of Education, College of Information Science and Engineering, Hunan University, Changsha 410082, China
Published: December 2020

Based on the angular spectrum theory, we establish a propagation model for vortex beam in reflection at an air-glass interface in the paraxial approximation, and investigate the cross polarization effects. When the horizontal polarization vortex beam is incident at different angles, the cross polarization component of the reflected beam shows a double-peak intensity distribution which is similar to the first-order Hermite-Gaussian mode. The distribution of horizontal polarization component is similar to that of the incident beam, and will show a double-peak intensity distribution which is perpendicular to the distribution of cross polarization components at the Brewster incidence. For the incident beam with arbitrary linear polarizations, we find that the polarized direction of cross polarization component is not perpendicular to the incident polarized direction, but exhibits an interesting rotational characteristic. The physical nature of this phenomenon is attributed to the different reflection coefficients of parallel and perpendicular polarizations. Experimental results agree well with our theoretical analysis.
Two-dimensional simulation of atmospheric pressure cold plasma jets in a needle-plane electrode configuration
Authors: Liu Fu-Cheng  , Yan Wen  , Wang De-Zhen  ,   School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024, China;,   College of Physics Science and Technology, Hebei University, Baoding 071002, China
Published: December 2020

The propagation mechanisms of atmospheric pressure cold plasma jets have recently attracted much attention. In this paper, by using a self-consistent two-dimensional plasma fluid model, we have investigated the propagation problems in the cold atmospheric pressure helium plasma jets that are surrounded by helium itself and thin dielectric tube, respectively. The spatio-temporal distributions of electron density, ionization rate, electrical field, and electron temperature were obtained. It is found that both the radius and the permittivity of dielectric tube have an impact on the discharge characteristics. A new method of improving the electron density and plasma jet size was also proposed.
Node importance ranking of complex networks
Authors: Liu Jian-Guo  , Ren Zhuo-Ming  , Guo Qiang  , Wang Bing-Hong  ,   Complex Systems Science Research Center, University of Shanghai for Science and Technology, Shanghai 200093, China
Published: December 2020

Identifying the most important nodes, or ranking the node importance by using the method of quantitative analysis in large scale networks are important problems in the complex networks. In this article, the metrics for node importance ranking in complex networks are reviewed and the latest progresses in this field are summarized from two prospects: the network structure and the spreading dynamics. The merits, weaknesses and applicable conditions of different node importance ranking metrics are analyzed. Finally, several important open problems are outlined as possible future directions.
Structure of CO monolayer on Cu(100)
Authors: Wu Tai-Quan  , Wang Xin-Yan  , Jiao Zhi-Wei  , Luo Hong-Lei  , Zhu Ping  ,   Department of Physics, China Jiliang University, Hangzhou 310018, China;,   Department of Physics, Zhejiang University, Hangzhou 310027, China
Published: December 2020

The first-principles technique is employed to determine the adsorption system of the CO monolayer on Cu(100) surface under the coverages of 1.00 ML, 0.50 ML and 0.25 ML. The calculation shows that the CO dimer is not stable enough. The atomic structures of CO monolayer on virtual Cu(100) surface and in the adsorption system on Cu(100) surface are proposed. In the CO/Cu(100) adsorption system, under the coverage of 1.00 ML the top and bridge sites are both stable, but the hollow site is not stable enough; under the coverages of 0.50 and 0.25 ML three adsorption sites are all stable. A comparison of the structure of the CO monolayer between before and after adsorption on Cu(100) surfrace shows that the interaction between the CO molecule and Cu(100) is clearly stronger than that between the CO monolayers.
A simplest parallel chaotic system of memristor
Authors: Xu Bi-Rong  ,   School of Mechanical and Electrical Engineering, Wuyi University, Wuyishan 354300, China
Published: December 2020

Based on a proposed voltage-controlled memristor, a simplest parallel memristor chaotic system is constructed. The dynamical characteristics of the new chaotic system are analyzed, including Lyapunov exponent, Lyapunov dimension, time domain waveforms, portrait diagrams, Lyapunov exponent spectrum, bifurcation diagrams and Poincar mapping. An electronic circuit of the new system is designed and verified by simulations using the EWB software. Research results show that with the parameter change, the i-v characteristic of the memristor, instead of keeping inclined 8-shaped, becomes a fan-shape with a tail. The differences between the chaotic system and the magnetic-controlled memristor chaotic system are in two aspects: only one equilibrium point in the chaotic system, and the initial conditions do not affect the state of the system when the system can oscillate. Good matching between numerical simulation and circuit experimental simulation proves the existence and physical realizability of the new chaotic system.
Simulation of two-dimensional droplet collisions based on SPH method of multi-phase flows with large density differences
Authors: Qiang Hong-Fu  , Shi Chao  , Chen Fu-Zhen  , Han Ya-Wei  ,   No. 601 Xi’an Hi-Tech Institute, Xi’an 710025, China
Published: December 2020

In this paper, the corrective continuity equation proposed by Ott and the momentum equation improved by Adami combine to solve two-dimensional simulation problems of droplet collisions in air. To effectively improve the calculation accuracy, the artificial viscosity equation and the artificial stress equation are derived which are suited for multi-phase flows with large density differences. This method is validated to be effective via examples of an initially square droplet under surface tension and in evolution process of two droplets in air. Droplet collisions for different Weber numbers (8.8, 19.8) and different impact parameters (0, 0.5) are simulated, all of which are compared with the results of VOF simulation. Through further calculation, distribution map of the two-dimensional droplet collision outcomes in air is obtained, which is in agreement with the experimental results. It is demonstrated that this method can be effective for solving problems of droplet collisions which are involved in multi-phase flows with large density differences, and is easily extended to three-dimensional simulation; thus it lays a foundation for further simulation of the secondary atomization in liquid rocket engines.
A full three-dimensional numerical diagnosis of Japan Atomic Energy Agency 10 Ampere multi-cusp negative hydrogen ion source
Authors: Yang Chao  , Liao Fang-Yan  , Xie Hong-Quan  ,   School of National Defense Science and Technology, Southwest University of Science and Technology, Mianyang 621010, China
Published: December 2020

This paper develops a full three-dimensional PIC/MCC algorithm, and uses it to conduct a full range of numerical diagnosis of the hot JAEA 10A ion source at home and abroad, explores lateral drift and energy distribution of electrons in the electron energy deposition process, analyzes the influence of the main physical parameters on the electronic deposition. Simulation and analysis results show that electronic horizontal shift (-Y direction) comes from the filtering zone of the magnetic drift. Increasing the filtering field, the magnetic drift increases, and lateral drift is aggravated, and the utilization of electronics increases; improving the discharge of chamber pressure, the electronic collision will be more frequent; thereby increasing lateral non-uniformity can improve the utilization of electronics.
Macrotransport analysis of effective mobility of biomolecules in periodic nano-filter polar arrays
Authors: Li Zi-Rui  , Liao Ning-Bo  , Zhou Yu-Qing  , Xue Wei  , Liu Mou-Bin  ,   College of Mechanical and Electrical Engineering, Wenzhou University, Wenzhou 325035, China;,   Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China
Published: December 2020

Transport of anisotropic biomolecules and/or charged Brownian particles in periodic porous media is of great importance in the fields of biomedicine, water treatment, and environmental engineering etc. In this paper, we present the modeling of transport of biomolecules in periodic polar arrays based on a numerical analysis of effective mobility. Anisotropic biomolecules are transformed to point-sized Brownian particles through introduction of configurational entropy, and the effective charge and effective transport parameters are calculated using macrotransport theory. As an example, the mobility of short dsDNA fragments in a nano-polar array is calculated. It is demonstrated that when the sizes of the gaps between the nano-poles are similar to or smaller than the size of biomolecules, the configurational entropy has a significant effect on the effective velocity. Difference in configurational entropy in the confined space dominates the partitioning of the molecules. In addition, as the effect of entropic barrier decreases with the strength of external electric field, relatively low voltage is preferred in order to achieve better selectivity.
Optical single sideband modulation with continuously tunable optical carrier-to-sideband ratio by employing a dual-parallel Mach-Zehnder modulator
Authors: Li Jing  , Ning Ti-Gang  , Pei Li  , Jian Wei  , You Hai-Dong  , Chen Hong-Yao  , Zhang Chan  , Li Chao  ,   Institute of Lightwave Technology, Beijing Jiaotong University, Beijing 100044, China
Published: December 2020

We propose and demonstrate an optical single sideband (OSSB) modulation approach with continuously tunable optical carrier-to-sideband ratio (OCSR) theoretically and experimentally. In the proposal, one dual-parallel Mach-Zehnder modulator (DP-MZM) acts as a key component. By properly setting the modulator, three separate sub-modulators inside the DP-MZM can be used to realize the OSSB modulation, optical carrier phase-shift, and lightwave interference. By adjusting the bias voltage of one sub-modulator, the OCSR can be tuned continuously. In the experiment, the tuning range of OCSR is found to be between-20.8 dB and 23.5 dB at modulation index m=0.2. We also analyze the relationship between the OCSR and RF power after detection. It is found that with properly adjusting the OCSR, the receiver sensitivity can be greatly improved.
An elastic-diffusion model for myosin Ⅵ molecular motor in a periodic potential field
Authors: Li Chen-Pu  , Han Ying-Rong  , Zhan Yong  , Hu Jin-Jiang  , Zhang Li-Gang  , Qu Jiao  ,   Department of Mathematics and Physics, Hebei Institute of Architecture Civil Engineering, Zhangjiakou, Hebei 075000, China;,   School of Science, Hebei University of Technology, Tianjin 300401, China
Published: December 2020

Because of the special structure and intracellular functions of myosin Ⅵ molecular motor, its dynamic principle has become a research focus. Starting from its structure and experimental phenomenon, the elastic-diffusion model of myosin Ⅵ in a periodic potential field is established, and the stochastic dynamics of the molecular motors, which conform to the Langevin equation, is analyzed by Monte Carlo simulations. By means of the environmental noise, myosin Ⅵ molecular motors could take stable stepping motion and effective transport according to its elastic potential energy and periodic potential of track, and a load can weaken the transportation power of the molecular motor system. For a given elastic coefficient, the longer the elastic chain of myosin Ⅵ, the lower the average velocity of it. By selecting a reasonable size of elasticity coefficient, the average velocity can be the maximum for a given elastic chain. In addition, the load can increase exponentially the mean dwelling time of myosin Ⅵ at the connection site.