bluuebunny/crossref_metadata_2025 huggingface dataset:
Microscopic theoretical investigation on propagation and breakdown depth of ultrashort-pulse laser in dielectrics
Authors: Li Dong-Hai  , Chen Fa-Liang  ,   Institute of Applied Physics and Computational Mathematics, Beijing 100088, China
Published: December 2020

Based on the Fokker-Planck equation along with laser propagation equation, a theoretical model that describes the ultrashort-pulse laser propagation characteristics and breakdown in dielectrics is established. Using this model, the conduction band electron densities and the electric field intensities at different positions in a dielectric material at different time are calculated. The variations of reflection, transmittance and energy deposition rate with input laser energy density are discussed. With the threshold conduction band electron density criterion, the breakdown depth in the material under varying laser energy density is calculated, which is found to increase first with laser energy density, and then to decline after reaching a maximum value. Effect of the spatial distribution of laser energy deposition on breakdown depth is analyzed. Meanwhile, the maximum value of breakdown depth is found to decrease as the laser pulse duration becomes shorter.
The n-type conduction and microstructural properties of phosphorus ion implanted nanocrystalline diamond films
Authors: Hu Xiao-Jun  , Hu Heng  , Chen Xiao-Hu  , Xu Bei  ,   College of Chemical Engineering and Material Science, Zhejiang University of Technology, Hangzhou 310014, China
Published: December 2020

Phosphorus ions are implanted into nanocrystalline diamond (NCD) films followed by being annealed at different temperatures. The results show that the samples exhibit good n-type conductivity when annealing temperature is increased to 800 ℃ and above. Raman spectroscopy and electron paramagnetic resonance measurements display that the sample with a larger quantity of diamond phase with better lattice perfection has a lower resistivity. It is indicated that nano-sized diamond grains make contributions to the n-type conductivity in the films. After 1000 ℃ annealing, the amorphous carbon grain boundaries become more ordered, which leads the dangling carbon bonds to decrease and the resistivity of the film to increases. It is revealed that the amorphous carbon grain boundaries supply a conduction path to the n-type phosphorus ion implanted nanocrystalline diamond grains.
A physical model to express grain boundaries in grain growth simulation by phase-field method
Authors: Zhang Xian-Gang  , Zong Ya-Ping  , Wang Ming-Tao  , Wu Yan  ,   (1)Key Laboratory of Anisotropy Design and Texture Engineering of Materials of Ministry of Education, Northeastern University, Shenyang 110004,China; (2)Key Laboratory of Anisotropy Design and Texture Engineering of Materials of Ministry of Education, Northeastern University, Shenyang 110004,China; Department of Mathematics and Physics, Shenyang University of Chemical Technology, Shenyang 110142, China; (3)Shanxi Taigang Stainless Steel Company Limited, Taiyuan 030003, China
Published: December 2020

Grain boundary model in phase-field simulation during microstructure evolution in solid states is discussed based on the way to express grain boundary and its physical background. The effects of different values of simulation parameters on feature of grain boundary in the phase field model are investigated systematically and a new conception of grain boundary range is suggested based on the simulation results of recrystallization of AZ31 magnesium alloy. The gradient range of the order parameter expresses the boundary range, whose physical meaning is found to be the range of grain boundary energy distribution across the boundary. The range is also corresponding to the segregation range of alloying elements around the boundary. It is shown that the gradient parameter determines the boundary range but the grain boundary energy is determined by both the gradient parameter and the coupling parameter. The effect of the boundary range value on microstructure feature is examined by simulating the recrystallization of the alloy. The simulation results are consistent well with reported experimental measurements when the boundary range has a value of 1.18 μm. Grain growth phase-field simulation in industrial space and time scale is realized for the first time using the new model developed by introducing the new conception of the grain boundary range.
Beam-wave interaction and simulation program for sheet beam klystron
Authors: Zhang Xiao-Feng  , Ruan Cun-Jun  , Luo Ji-Run  , Ruan Wang  , Zhao Ding  ,   (1)Key Laboratory of High Power Microwave Sources and Technologies, Institute of Electronics, Chinese Academy of Sciences, Beijing 100190, China; (2)Key Laboratory of High Power Microwave Sources and Technologies, Institute of Electronics, Chinese Academy of Sciences, Beijing 100190, China; Graduate University of Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

In this paper, a 2.5-dimensional macro-particle model is proposed for a nonaxisymmetrical and large width-height ratio sheet beam klystron (SBK) and a corresponding beam-wave interaction program is developed. An X-band 100-MW SBK is simulated for testing the computing capability of the program. The results are in good agreement with those from 3D PIC software, and the computation time can greatly be reduced, which is useful for the initial design and the optimization of the SBK beam-wave interaction structure.
A traffic flow lattice model with the consideration of driver anticipation effect and its numerical simulation
Authors: Sun Di-Hua  , Tian Chuan  ,   College of Automation, Chongqing University, Chongqing 400030, China
Published: December 2020

With the consideration of the effect of driver anticipation behavior on traffic flow, a new one-dimensional lattice model is proposed. The linear stability condition of the presented model is obtained by employing the linear stability theory. The density wave near the critical stable point is investigated analytically with the nonlinear analysis method. The results show that the occurrence of traffic jamming transitions can be described by the kink-antikink solution of the modified Korteweg-de Vries (mKdV) equation. The good agreement between the simulation results and the analytical results shows that the stability of traffic flow can be enhanced when the effect of driver anticipation behavior is considered.
Analysis on the topological properties of the linkage complex network between crude oil future price and spot price
Authors: Gao Xiang-Yun  , An Hai-Zhong  , Liu Hong-Hong  , Ding Ying-Hui  ,   (1)Lab of Resources and Environmental Management, China University of Geosciences, Beijing 100083, China; (2)School of Humanities and Economic Management, China University of Geosciences, Beijing 100083, China
Published: December 2020

This paper analyzes the linkage between crude oil future price and spot price based on complex network theory. The linkage between oil future price and Daqing (China) crude oil spot price from November 25, 2002 to September 24, 2010 is transformed into symbolic sequences consisted of three characters {Y, O, N} through the process of coarse graining. The nodes of the complex network are 5-symbol strings in the number of 177 in the form of data window linked in the networks topology by sliding sequence. The complexity of the linkage is verified through analyzing the topological properties of point of strength, strength distribution, weighted clustering coefficient, average shortest paths, betweenness centrality and subgroup in the complex network. The results indicate that the point of strength value of the former 32 nodes is larger, cumulative strength distribution is 73.27%, and most fluctuation models linkages have the character with the same direction. However, it does not show a good correlation between weighted clustering coefficient and point of strength. There are some small cluster groups appearing in the network. These small cluster groups constitute two camps whose cores are YYYYY node and NNNNN node. The results also show that average shortest paths length is 6.969 and 11.3% of nodes occupying 1/4 of centrality function, and there are not many subgroups with close linkage, which verifies the complex characteristics of the linkage fluctuation in the network topology. This paper finds the power law, clustering and periodicity between two kinds of prices in the long run, which is of great significance in grasping the crude oil market, predicting oil price volatility reasonable, formulating price and avoiding risk.
Global attractor of strongly damped nonlinearthermoelastic coupled rod system
Authors: Zhang Jian-Wen  , Li Jin-Feng  , Wu Run-Heng  ,   (1)College of Science, North China University of Technology, Beijing 100041,China; (2)College of Science, Taiyuan University of Technology,Taiyuan 030024, China
Published: December 2020

In this paper, we prove the existence of the global attractor for strongly damped nonlinear thermoelastic coupled rod equation with the initial boundary value, and make the dimension estimate of the global attractor, according to the operator semigroups theory.
Error estimate of element-free Galerkin method for elasticity
Authors: Cheng Yu-Min  , Cheng Rong-Jun  ,   (1)Department of fundamental course, Ningbo Institute of Technology, Zhejiang University, Ningbo 315100, China;Shanghai Institute of Applied Mathematics and Mechanics, Shanghai University,Shanghai 200072, China; (2)Shanghai Institute of Applied Mathematics and Mechanics, Shanghai University,Shanghai 200072, China
Published: December 2020

Based on both the error estimates of moving least-square approximation in the Sobolev space Wk,p(Ω) and the continuity and coercion of the bi-linearity in the weak form of the elasticity, the error analysis of element-free Galerkin method for elasticity is discussed in this paper, the relationship between the error and the radius of the weight function is given, and the theorem of the error estimate presented. The error estimate proves to be of optimal order when nodes and shape functions satisfy some conditions. From the error analysis, it is shown that the error bound of the elasticity is directly related to the radius of the weight function. And a numerical example is given to verify the correctness of the given results.
Controlling fractal erosion of safe basins in a Helmholtz oscillator by delayed position feedback
Authors: Shang Hui-Lin  ,   School of Mechanical Engineering, Shanghai Institute of Technology, Shanghai 200235,China
Published: December 2020

A linear delayed position feedback is introduced into a Helmholtz oscillator system, and its effects on controlling the erosion of safe basins are investigated. The condition of fractal erosion of the basin boundary of the delayed feedback controlled system is acquired, there by the threshold of the excitation of the fractal erosion is obtained. Then considering time delay as a variable parameter and employing the 4th-order Runge-Kutta method and the point-to-point mapping method, evolutions of safe basins with time delay are presented. It is found that the increasing of time delay can enhance the threshold of the fractal erosion and reduce the erosion of safe basin effectively under a weak feedback gain. All the results imply that delayed position feedback can be used as a good strategy to control the erosion of safe basins.
Breakability of chaotic direct sequence spreading spectrum secure system under multi-path fading channel
Authors: Bai Lu  , Guo Jing-Bo  ,   State Key Lab, Department of Electrical Engineering, Tsinghua University, Beijing 100084,China
Published: December 2020

Blind demodulation (breaking) of chaotic direct sequence spread spectrum (CD3S) signals is a challenging and leading issue under multipath fading channel in the field of chaotic communication. Until now, there are neither equalization methods to remove the impact of the channel, nor the immediate breaking methods. Based on the existing study, the breakability of CD3S signals is analyzed under multipath fading channel by using unscented Kalman filter (UKF) chaotic fitting in this paper. Beginning with the state space equation for the CD3S signals in UKF chaotic fitting, the channel influence on the tracking error is analyzed in the process of UKF chaotic fitting, then the range of the message state estimation is derived, and finally a sufficient condition theorem is proposed for the CD3S signals to be broken. Simulation results show that CD3S signals can be broken successfully under the proposed condition with excellent performance of bit error rate (BER), no matter whether the channel characteristic is either time-invariant or time-variant.
Fractional order modeling and simulation analysis of Boost converter in continuous conduction mode operation
Authors: Wang Fa-Qiang  , Ma Xi-Kui  ,   State Key Laboratory of Electrical Insulation and Power Equipment, School of Electrical Engineering, Xi'an Jiaotong University, Xi'an 710049, China
Published: December 2020

Based on fractional calculus and the fact that the capacitor and the inductor are fractional in nature, the fractional mathematical model and the fractional state averaged model of the Boost converter in continuous conduction mode operation are built and analyzed. Also, the condition for the continuous conduction mode operation of the Boost converter is given. Finally, in order to verify the theoretical analysis, the simulation model of the Boost converter in continuous conduction mode operation is established by using the software of Matlab/Simulink.
Non-smooth bifurcation in nonlinear electrical circuits with multiple switching boundaries
Authors: Zhang Yin  , Bi Qin-Sheng  ,   Faculty of Science, Jiangsu University, Zhenjiang 212013, China
Published: December 2020

The fast-slow dynamics of a nonlinear electrical circuit with multiple switching boundaries is investigated in this paper. For suitable parameters, periodic bursting phenomenon can be observed. The full system can be divided into slow and fast subsystems because of the difference between variational speeds of state variables. According to the slow-fast analysis, the slow variable, which modulates the behavior of the system, can be treated as a quasi-static bifurcation parameter for the fast subsystem to analyze the stabilities of equilibrium points in different areas of vector field. The bifurcation is dependent on the switching boundary in the vector field. In particular, for the two-time scale non-smooth system with fast-slow effect, the bifurcation of fast subsystem is determined by the characteristics of equilibrium points on both sides of the switching boundary. Furthermore, the generalized Jacobian matrix at the non-smooth boundary is introduced to explore the type of non-smooth bifurcation (i.e., multiple crossing bifurcation) in the fast subsystem, which can also be used to explain the mechanism for symmetric bursting phenomenon of the full system.
Parameter identification of generalized Julia sets
Authors: Liu Shu-Tang  , Qiao Wei  , Sun Jie  ,   (1)Lab and Equipment Management Office, Shandong University at Weihai, Weihai 264209, China; (2)School of Control Science and Engineering, Shandong University, Jinan 250061, China; (3)School of Control Science and Engineering, Shandong University, Jinan 250061, China;School of Mechanical, Electrical & Information Engineering, Shandong University at Weihai, Weihai 264209, China
Published: December 2020

In this paper, a class of wide range Julia set of parameter identification problem is investigated. Based on the nonlinear feedback controller and the discretized equation theory, the designed generally applicable adaptive synchronization controller and the parameter adaptive law are obtained, and it is proved that the designed controller of generalized Julia set can achieve the synchronization. Moreover, it can identify the unknown parameters of the generalized Julia set. Particularly, the parameter identification of the basic form of Julia set is discussed in the paper.
Estimating parameters of chaotic system with variational method
Authors: Cao Xiao-Qun  , Song Jun-Qiang  , Zhang Wei-Min  , Zhao Jun  , Zhang Li-Lun  ,   School of Computer Science, National University of Defense Technology, Changsha 410073, China
Published: December 2020

In this paper a method is presented to estimate the unknown parameters of chaotic system based on the variational principle, which can be applied to all chaotic systems governed by the following equation:x= F(x,θ). Firstly,the equation of the chaotic system is included into the objective functional. Secondly, the universal formulas of the adjoint equation for chaotic systems and the functional gradient for unknown parameters are derived using the variational principle. Thirdly, the algorithm to estimate unknown parameters of chaotic system is designed according to above formulas. Finally, all unknown parameters of the typical Lorenz chaotic system and the hyperchaotic Chen system are estimated separately. Numerical simulations show that the effectiveness and the feasibility of the proposed method to estimate unknown parameters of chaotic systems.
Soliton characteristics of two-dimensional condensates with two- and three-body interaction
Authors: Zhang Wei-Xi  , She Yan-Chao  , Wang Deng-Long  ,   (1)Department of Physics and Electronic Science, Tongren University,Tongren 554300,China; (2)Department of Physics and Key Laboratory of Quantum Engineering and Micro-Nano Energy Technology of the Education Bureau of Hunan Province, Xiangtan University,Xiangtan 411105,China
Published: December 2020

By using multiple-scale method, we study analytically the soliton characteristics of the two-dimensional condensates with two- and three-body interaction. The results show that a ring dark soliton can be found in the condensates when the two-body interaction is repulsive and three-body interaction is attractive. With the strength of the three-body interaction decreasing, the height of the center peak of the ring dark soliton decreases. When the three-body interaction vanishes, the ring dark soliton becomes a perfect dark soliton. If the two- and the three-body interaction are both repulsive,the width and the amplitude of the dark soliton decrease with the strength of the three-body interaction increasing. Especially, if the strength of the three-body interaction is large, which is on the order of that of the two-body interaction, the condensat collapse takes place.
Calibration-free wavelength modulation absorption spectrum of gas
Authors: Li Ning  , Weng Chun-Sheng  ,   National Key Lab of Transient Physics, Nanjing University of Science and Technology, Nanjing 210094, China
Published: December 2020

The calibration-free wavelength modulation absorption spectrum is studied based on the second harmonic (2f) signal to remove the calibration procedure for tunable diode laser absorption gas sensing. The simulated 2f signal is obtain from the analysis of peak and trough from measured 2f signal line shape. The gas concentration is calculated by the linear fitting of measured and simulated 2f signals. The experiment on CO2 detection is carried out at transition of 6336.24cm-1 in a 10 cm absorption cell. The results prove that the calibration-free wavelength modulation absorption spectrum is suited for on-site gas sensing at various conditions. The average absolute error of gas concentration is 0.67% at modulation index ranging from 1.8 to 3.2. With gas concentration and pressure varied, the average absolute errors of gas concentration are measured to be about 0.98% and 0.74%.
In-flight polarization calibration methods of directional polarizedremote sensing camera DPC
Authors: Xie Dong-Hai  , Gu Xing-Fa  , Chen Xing-Feng  , Li Zheng-Qiang  , Cheng Tian-Hai  , Yu Tao  , Xu Hua  ,   State Key Laboratory of Remote Sensing Science, Institute of Remote Sensing Applications, Chinese Academy of Sciences, Beijing 100101, China;Graduate University of Chinese Academy of Sciences, Beijing 100049, China;Demonstration Center of Spaceborn Remote;,   State Key Laboratory of Remote Sensing Science, Institute of Remote Sensing Applications, Chinese Academy of Sciences, Beijing 100101, China;Graduate University of Chinese Academy of Sciences, Beijing 100049, China;State Environmental Protection Key Labor,   null
Published: December 2020

In order to make a good use of Chinese polarized satellite sensor, the directional polarized camera (DPC) has been developed and tested in the flight experiments. DPC camera is designed to observe the polarized and directional reflected radiation of the earth-atmosphere system. Retrieval of physical parameters from DPC data depends on the accuracy of calibration. The polarized camera radiative calibration includes two aspects: intensity and polarization. Based on the predecessors' work, we explore the polarization calibration principles and methods. Using the DPC aerial remote sensing experiment data, we have realized the polarization calibration and analyzed the results. This work may contribute to fundamental basis for the data processing and in-flight calibration of the future Chinese polarized satellite sensor.
Frequency responses of communication avalanche photodiodes
Authors: Mo Qiu-Yan  , Zhao Yan-Li  ,   Optoelectronic Science and Engineering of Huazhong University of Science, National Laboratoryfor Optoelectronics, Wuhan 430074, China
Published: December 2020

In recent years, separate absorption, charge and multiplication avalanche photodiodes (SACM-APDs), including InP/InGaAs, InAlAs/InGaAs and Si/Ge APD, have drawn a lot of attention in the field of optical communication. In this paper, on the basis of the circuit model, the frequency response is studied systematically for APDs with different thicknesses of epitaxial layers, different multiplication materials and device structures. The effects of the absorption layer thickness, the dimension of the active area and the parasitic parameters on frequency response are addressed to Si/Ge APD. The simulation resuets are in good agreement with the experimental results, which indicates that the circuit model is helpful for the design optimization of APDs.
Ab initio study on CH3C(O)OSSOC(O)CH3: configurations and energies
Authors: Wang Ke-Dong  , Gu Jun  , Zhu Chuan-Chuan  , Liu Yu-Fang  ,   (1)Department of Physics, Henan Normal University, Xinxiang 453007, China; (2)School of Continuing Education, Xinxiang Radio and Television University,Xinxiang 453003, China
Published: December 2020

The five low-lying configurations of CH3C(O)OSSOC(O)CH3 are studied by ab initio calculations by B3LYP, MP3 and MP4 methods with Aug-cc-pVDZ basis set. Their rotational constants and dipole moments of these five configurations are determined. The vertical ionization energies of the configurations, calculated with electron propagator theory in the P3/6-311++G(2d,2p) approximation, are in agreement with the experimental data from photoelectron spectroscopy. The relative energies of the configurations and the comparison between the simulated and the experimental photoelectron spectra demonstrate that there are at least two configurations of CH3C(O)OSSOC(O)CH3 in the gas-phase experiments. The geometrical parameters of five lowest-lying configurations are optimized in the cationic state and compared with those of the neutral configuration. Remarkable structural relaxations after ionization are found, especially for the dihedral angles D(C2O4S5S10) and D(O4S5S10O9).
Measurement of lifetime of ultracold cesium Rydberg states
Authors: Feng Zhi-Gang  , Zhang Hao  , Zhang Lin-Jie  , Li Chang-Yong  , Zhao Jian-Ming  , Jia Suo-Tang  ,   State Key Laboratory of Quantum Optics and Quantum Optics Devices, College of Physics and Electronics Engineering, Shanxi University, Taiyuan 030006, China
Published: December 2020

In this paper, the cold cesium atoms are excited to Rydberg states via two-photon transition and the ion signal of Rydberg atoms is obtained by the selective field-ionization method. The evolution of the 36D and 34S states population is acquired by changing delay time; the corresponding effective lifetimes are obtained by fitting the experimental data, which are in agreement with the existing theoretical results.
Squeezing properties of two-mode squeezed field interacting with V-type three-level atoms
Authors: Li Ming  , Tang Tao  , Chen Ding-Han  ,   Department of Mathematics and Physics, Guilin University of Technology, Guilin 541004, China
Published: December 2020

The Hamiltonian operator of a system of V-type three-level atomic Bose-Einstein condensate interacting with two-mode squeezed coherent light field is analyzed in terms of the lattice-liquid model. It is indicated that the contribution of the interaction between atoms to the Hamiltonian in the literature is unreasonable,so the Hamiltonian operator is improved and the squeezing properties of two-mode squeezed field interacting with V-type three-level atoms are studied. The results show that two quadrature comonents of light can be squeezed periodically and that maximum depth of squeezing is closely related to the initial squeezing parameter of light and that the duration is determined by the frequency of two-mode field.
Comparative study of partially coherent vortex beam propagations through atmospheric turbulence along a uplink path and a downlink path
Authors: Li Jin-Hong  , Lü Bai-Da  ,   (1)Institute of Laser Physics and Chemistry, Sichuan University, Chengdu 610064, China; (2)School of Applied Science, Taiyuan University of Science and Technology, Taiyuan 030024 , China;Institute of Laser Physics and Chemistry, Sichuan University, Chengdu 610064, China
Published: December 2020

Based on the extended Huygens-Fresnel principle, the propagations of a partially coherent vortex beam through atmospheric turbulence along an uplink path and a downlink path are studied, where the Gaussian Schell-model (GSM) vortex beam is taken as a typical example of partially coherent vortex beam. The analytical expressions for the average intensity, rms width and cross-spectral density function of GSM vortex beam propagating through atmospheric turbulence along a slant path are derived and used to study the influence of atmospheric turbulence along an uplink path and a downlink path on GSM vortex beam propagation and on coherence vortex. It is shown that under the same conditions the influence of atmospheric turbulence along a downlink path on GSM vortex beam propagation is smaller than that along a uplink path, and the conservation distance of the topological charge of GSM vortex beam along a downlink path is longer than that along a uplink path. The results are explained in physics.
Transverse angular shift in optical Magnus effect
Authors: Zhang Li  , Luo Hai-Lu  , Wen Shuang-Chun  ,   Key Laboratory for Micro/Nano Optoelectronic Devices of Ministry of Education, School of Information Science and Engineering, Hunan University, Changsha 410082, China
Published: December 2020

Starting from the plane angular spectrum theory, we establish a transmission model of beam refraction at the interface between air and glass. Based on this model, we reveal a transverse angular shift in the optical Magnus effect. For a certain linearly and elliptically polarized light beam, the field centroid of refraction beam exhibits a transverse angular shift. However, the transverse angular shift would vanish when the incident light beam is circularly polarized. At an interface between positive and negative refractive indexes, the transverse angle shift presents a reversed phenomenon which is caused by negative diffraction in the left-handed materials. Ultra-high refractive index can significantly reduce the transverse angular shift. On the contrary, the ultra-low refractive index can significantly enhance the transverse angular shift. These findings provide a new method of how to adjust and enhance the optical Magnus effect.
Anomalous rotation characteristics of circularly polarized beam in left-handed materials
Authors: Liu Sen  , Luo Hai-Lu  , Wen Shuang-Chun  ,   Key Laboratory for Micro/Nano Optoelectronic Devices of Ministry of Education, School of Information Science and Engineering,Hunan University,Changsha 410082, China
Published: December 2020

According to Whittaker scalar theory, a vector transmission model of circularly polarized beam is established. Based on this model, the anomalous rotating characteristics of circularly polarized beam in left-handed materials are investigated. By analyzing the polarization state and diffraction, the abnormal rotation characteristics of beam centroid are revealed. When the circularly polarized light beam propagates in a left-handed material,the rotation characteristic is reversed and the corresponding rotation angle is equal to the Gouy phase. We find that this abnormal rotating characteristic is caused by the reversed transverse energy flow. These findings provide a better understanding of the transmission characteristics of beam in left-handed materials.
Propagation of elliptical Gaussian beam in uniaxialcrystal orthogonal to the optical axis
Authors: Huang Yong-Chao  , Zhang Ting-Rong  , Chen Sen-Hui  , Song Hong-Yuan  , Li Yan-Tao  , Zhang Wei-Lin  ,   Institute of Physics and Electronic Engineering, Sichuan Normal University,Chengdu 610066, China
Published: December 2020

Based on the paraxial vectorial theory of the propagation of beam in uniaxially anisotropic medium,the analytical formula for an elliptical Gaussian beam propagating in uniaxial crystal orthogonal to the optical axis is derived. And some numerical simulations were preformed to study the effect of the anisotropy on the polarization property of the diffracted elliptical Gaussian beam in the output plane. The results show that the linear polarization state and the symmetry of beam cannot remain unchanged during propagation due to the anisotropy of crystals.
High-accuracy quasi-distributed optical fiber Bragg gratingseismic demodulation system
Authors: Qiao Xue-Guang  , Ding Feng  , Jia Zhen-An  , Fu Hai-Wei  , Ying Xu-Dong  , Zhou Rui  , Song Juan  ,   Ministry of Education Key Laboratory of Photoelectricity Gas-oil Logging and Detecting, Xi'an Shiyou University, Xi'an 710065, China;,   Ministry of Education Key Laboratory of Photoelectricity Gas-oil Logging and Detecting, Xi'an Shiyou University, Xi'an 710065, China;Northwest University, Xi'an 710069, China;,   Ministry of Education Key Laboratory of Photoelectricity Gas-oil Logging and Detecting, Xi'an Shiyou University, Xi'an 710065, China;Zhongyuan Oilfield Petro Chemical Complex of Sinopec, Puyang 457061, China;,   Northwest University, Xi'an 710069, China
Published: December 2020

A new earthquake detection demodulation system for monitoring several points and several parameters at the same time is proposed by using the linear sideband of super-fluorescent fiber source as an edge filter. The sensitivity of whole demodulation system is determined by the detecting sensitivity of source light. Through the optimization of light, the slope of light linear part is improved greatly. According to the rising and the falling of light, the system is divided into two parts each with four channels. Through the stimulation experiments of all the channels, the static wavelength sensitivities of the two parts are 887.5 mV/nm and -971.7 mV/nm, and their stain resolutions reseach 0.95με and 0.86με respectively. This demodulation system has high sensitivity, good stability, quick demodulation speed, etc. It is the most important is that it can realize real-time detection for several points and several parameters at the same time.
Terahertz transmission optical fiber with low absorptionloss and high birefringence
Authors: Fu Xiao-Xia  , Chen Ming-Yang  ,   School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013, China
Published: December 2020

A novel terahertz transmission optical fiber with low absorption loss and high birefringence is proposed. The proposed fiber is composed of alternate teflon and air-hole layers to form a two-fold symmetry configuration. Using the finite element method, the dependences of absorption loss and birefringence on the configuration parameter of the fiber are presented. The numerical results show that the birefringence can reach as large as 0.08. In addition, when the mode absorption loss is less than 20 dB/m,the birefringence can still be larger than 0.02.
Resonance tunneling through photonic double quantum well system
Authors: Zhou Fei  , Yang Yi-Biao  , Liang Jiu-Qing  , Fei Hong-Ming  ,   (1)Department of Physics and Optoelectronics,Taiyuan University of Technology, Taiyuan 030024, China; (2)Institute of Theoretical Physics and Department of Physics, Shanxi University, Taiyuan 030006, China
Published: December 2020

Resonant tunneling of light through double-well structure is investigated by the R-matrix algorithm. We find that the resonant frequency can be controlled by the coupling strength between the two wells. The transmission probability shows the 2-fold peak-splitting in a symmetric double-well system, and the distortion of the resonance peak-splitting in an asymmetric double-well system. The distortion of the resonance peak-splitting by alternately placing Right-hand and Left-hend materials in the two wells is different from that resulted from the asymmetry of well-width. Moreover the distortion of the resonance peak-splitting is analyzed by means of the one-dimensional photonic QW system. The former can be understood by the destructive interference, which may lead to the complete cancellation of resonant mode, while the latter is due to the relative sifts of eigenmodes in the two wells.
Stochastic resonance mechanism for wideband and low frequency vibration energy harvesting based on piezoelectric cantilever beams
Authors: Chen Zhong-Sheng  , Yang Yong-Min  ,   Institute of Mechatronic Engineering, College of Mechatronic Engineering and Automation, National University of Defense Technology, Changsha 410073, China
Published: December 2020

A stochastic resonance mechanism of improving wideband and low frequency vibration energy harvesting of piezoelectric cantilever beam (PCB) is studied using the system nonlinearity. By adding a pair of rectangular permanent magnets, the structure of standard piezoelectric cantilever beam is improved. Results reveal that the improved PCB may be a bistable system under a nonlinear magnetic force and an appropriate distance between two magnets. Then a stochastic resonance phenomenon will happen by the input of wideband and low frequency stochastic vibrations. Under the condition of stochastic resonance, the electrical output of the improved PCB increases greatly. So the proposed method will be useful for extending the resonant band and improving the electrical output of a standard PCB.
First-principles calculation for elastic constantsof α-ScDx(D=H, He)
Authors: Fan Kai-Min  , Yang Li  , Peng Shu-Ming  , Long Xing-Gui  , Wu Zhong-Cheng  , Zu Xiao-Tao  ,   (1)Department of Applied Physics, University of Electronic Science and Technology of China, Chengdu 610054, China; (2)Department of Applied Physics, University of Electronic Science and Technology of China, Chengdu 610054, China;Department of Physics and Engineering Technology, Sichuan University of Arts and Science, Dazhou 635000, China; (3)Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

The elastic constants of α-ScH x (x=0, 1/4, 1/8, 1/32) and α-ScHe x (x=0, 1/4, 1/8, 1/32) are studied by the first-principles method. It is found that the addition of hydrogen to the scandium has an effect greatly different from the addition of helium to this rare-earth metal. The elastic constants of the α-ScH x system almost increase with hydrogen concentration increasing, which is in agreement with the experimental observation. Whereas, in the case of α-ScHe x system, the elastic constants almost decrease with the increase of helium concentration.
Compare study on the explosion characteristics of nano-aluminum and micro-aluminum
Authors: Yan Zheng-Xin  ,   Key Laboratory of Western Mine Exploitation and Hazard Prevention of the Ministry of Education, Xi'an University of Science and Technology, Xi'an 710054, China;Faculty of Science, Xi'an University of Science and Technology, Xi'an 710054, China
Published: December 2020

The explosion characteristic of propylene oxide/nano-, micro-alumium component were comparably investigated under the changed induced incident shock waves. The ignition delay times of two explosion systems were determined by the monochromater synchronous test technology. The structure, morphology, surface oxide layer of the products were analyized by scanning electron microscopy(SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The results indicated that the products of nano-Al are the spongy-structure, need-structure and fiber-structure, the morphology of the products of microsize aluminum is mainly in spherical structure. The different phases of alumina(α,β,γ,ε,δ) in compress section , ignition section, combustion section, explosion section, propagation section, and compressed products section was revealed by XRD data. It shows that the reaction in nano-Al reaction system is more violent than that in micro-Al one and the decreasing temperature align the axial cause the different phases of alimina . XPS spectrum show that the oxide layers on the surface of nano-alumina is about 35nm, alumina is almost is 92%; while the oxide layer on the surface of micro-alumina is 30nm, alumina is merely 65%. The experimental results that indicated the existing two different ignition mechanisms and combustion mechanism will be useful to the addition of energy material.
Rheological study of silica nanoparticle monolayers via two orthogonal Wilhelmy plates
Authors: Langevin Dominique  , Zhang Yong-Jian  , Zang Du-Yang  ,   (1)Key Laboratory of Space Applied Physics and Chemistry of Ministry of Education, School of Science, Northwestern Polytechnical University, Xi'an 710072, China; (2)Laboratoire de Physique des Solides, Université Paris-Sud, UMR CNRS 8502, Batiment 510, 91405 Orsay cedex, France; (3)School of Materials Science and Engineering, Northwestern Polytechnical University, Xi'an 710072, China
Published: December 2020

We investigate the rheological properties of silica nanoparticle monolayers at the air-water interface by using two orthogonal Wilhelmy plates in the Langmuir trough and Brewster angle microscopy (BAM). Remarkable anisotropic effect of surface pressure is observed when the layers are fully covered by particles. The pressure anisotropy is the most prominent for the layer of particles with 34%SiOH on their surface. The elastic compression and the shear moduli present the maxima at intermediate hydrophobicity. The dependence of rheological properties on particle hydrophobicity is closely related to the foamability and the stability of the foams made from these particle dispersions. A shape memory effect is observed in the condensed layer of the most hydrophobic particle(20%SiOH), which may result from the irreversible organization of particles and the particle arrangement driven by the inner stress stored in the layer.
Effects of Ge fraction on electrical characteristics of strained Si1-xGe x channel p-MOSFET
Authors: Yang Zhou  , Wang Chong  , Wang Hong-Tao  , Hu Wei-Da  , Yang Yu  ,   (1)Institute for Optoelectronic Information Materials, Yunnan University, Kunming 650091, China; (2)National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083, China
Published: December 2020

The capacitance-voltage characteristics and the variations of threshold voltage of strained Si1-xGe x channel p-MOSFET with Ge fraction are investigated via two-dimansional numerical simulation. The results indicate that with the increase of Ge fraction, the subthreshold current increases remarkably, and that the gate capacitance changes significantly when the device is in inversion, moreover, the Ge fraction dependence of the variation of threshold voltage is linear. Combining the change of the Si1-xGex channel length with the relevant physical model, the mobility of holes in channel is demonstrated to be inversely proportional to the derivative of the total resistances with respect to the channel length in a weak applied field.
First principles investigation of electronic structuresand stabilities of Mg2Ni and its complex hydrides
Authors: Liu Chun-Hua  , Ouyang Chu-Ying  , Ji Ying-Hua  ,   Department of Physics of Jiangxi Normal University, Key Laboratory of Photo Electronic & Telecommunicationof Jiangxi Province, Nanchang 330022, China
Published: December 2020

First-principle calculations are carried out to investigate the energies and the electronic structures of Mg2Ni alloy and its high/low temperature hydrides. Results show that strong bonding interaction between Mg and Ni atoms exists in the Mg2Ni alloy. With H inserted, the charge transfer occurs from Mg to Ni-3d, which gives rise to a band gap between Ni-3d and Ni-4p orbitals. The interaction between Mg and Ni in LT/HT-Mg2NiH4 hydrides is weakened due to the covalent bonding between Ni-4s and H-1s. Therefore, it neads more energy to remove H atoms from LT-Mg2NiH4 than from HT-Mg2NiH4, indicating that HT-Mg2NiH4 is more suitable for de-hydrogenation reaction while the LT-Mg2NiH4 is suitable for hydrogenation reaction.
The first principles study on mechanical propertiesof He doped grain boundary of Al
Authors: He Jie  , Chen Jun  , Wang Xiao-Zhong  , Lin Li-Bin  ,   (1)Department of Physics and Key Laboratory for Radiation Physics and Technologyof Ministry of Education, Sichuan University, Chengdu 610064, China; (2)Institute of Applied Physics and Computational Mathematics, Beijing 100083, China; (3)Institute of Applied Physics and Computational Mathematics, Beijing 100083, China;Department of Physics and Key Laboratory for Radiation Physics and Technologyof Ministry of Education, Sichuan University, Chengdu 610064, China
Published: December 2020

According to the first principles methods, we theoretically study the mechanical properties of He doped AlΣ3 grain boundary (GB). Our results show that He has the lowest formation energy 2.942 eV in GB and low segregation energy 0.085 eV from bulk to GB. Under the extending tensile, the clean GB has a theoretical strength of 8.95 GPa, and the crack appears first from the GB. While, after the He doping, the tensile strength reduces to 7.14 GPa, and one flat effect is present in the curve of strain-stress. By analyzing the variation of the bond-length and the charge distribution, we believe that He-induced reduction of tensile strength is probably ascribed to the weaker interaction between He and Al atoms as well as the weakening Al-Al bonds, owing to the charge screening by full-shell electron structure of He.
Model of intrinsic carrier concentrationof [110]/(001)-uniaxial strained Si
Authors: Wang Guan-Yu  , Ma Jian-Li  , Zhang He-Ming  , Wang Xiao-Yan  , Wang Bin  ,   Key Laboratory for Wide Band-Gap Semiconductor Materials and Devices,School of Microelectronics, Xidian University, Xi'an 710071, China
Published: December 2020

In this paper, the effect of uniaxial stress along [110] direction on the energy-band structure parameters of (001)-bulk Si is discussed, thereby we investigate the equilibrium carrier concentration and the expressions of effective density of state (DOS) in conduction and valence band, which contain explicit physical significance. The model of intrinsic carrier concentration is proposed by combining the expressions of DOS and bandgap. The pro- posed method in this paper is also applicable to modeling the intrinsic carrier concentration under the action of uniaxial stress along an arbitrary direction, and provides some references for design, mode- ling and simulation of similar uniaxial strained Si devices.
Current collapse effect, interfacial thermal resistance and work temperature for AlGaN/GaN HEMTs
Authors: Gu Jiang  , Wang Qiang  , Lu Hong  ,   (1)Department of Physics and Electronic, Changshu Institute of Technology, Changshu 215500, China; (2)School of Electronics and Information, Nantong University, Nantong 226019, China
Published: December 2020

The effects of operating temperature and the interfacial thermal resistance on device are researched by using a two-dimensional numerical simulator. A comparison between the simulated results and the experiment data demonstrates that hot electrons make a significant contribution to the negative differential output conductance which will increase with the increase of the work temperature under low drain voltage, and under upper drain voltage, the self-heating effect is an important factor to the current collapse which will become more serious with the work temperature and interfacial thermal resistance inereasing.
Properties of pumping current under microwave field appliedto a quantum dot with over-dot tunneling
Authors: Zhou Yun-Qing  , Kong Ling-Min  , Wang Rui  , Zhang Cun-Xi  ,   Department of Physics, Zhejiang Ocean College, Zhoushan 316000, China
Published: December 2020

The evolution-operator approach is applied to studying photon-electron pumping effects on a quantum dot connected to two magnetic leads in the presence of both via-dot and over-dot tunneling channels. It is found that a microwave field applied to the quantum dot may give rise to charge and spin pumpings at zero-bias voltage for asymmetric magnetic junctions. More interestingly, a pure spin current can be pumped for symmetric magnetic junctions in the anti-parallel magnetization configuration, providing a new scheme for the design of spin batteries.
Spin injection in GaAs and giant Hall effect
Authors: Wang Zhi-Ming  ,   Institute of Mechanical Engineering Nanjing University of Science and Technology, Nanjing 210094, China;Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093, China
Published: December 2020

In spintronics, general spin injection is achieved by the superlattice, spin valve, tunnel junction, other typical method of spin injection is to dilute magnetic semiconductor such as: GaMnAs. In this paper, spin Fe particles are injected into the GaAs matrix by using the magnetron sputtering to form the granular film (GaAs)19Fe81, in which saturated Hall resistivity ρxys is shown to be 15 μΩ·cm at room temperature, which is about 2 orders larger than that of pure Fe. So the spin injection is successfully realized.
Calculation of electrical resistivity of liquid Pb
Authors: Guo Feng-Xiang  , Lü Ting  , Jia Yan  , Tian Xue-Lei  ,   Key Laboratory for Liquid-Solid Strctural Evolution & Processing of Materials Ministry of Education,Shandong University, Ji'nan 250061, China
Published: December 2020

A new model pseudopotential is presented following Behari's model and used in the calculation of the electrical resistivity of liquid Pb, with the help of experimental structure factor and hard-sphere structure factor. The results are in good agreement with the experimental data. The validity of the model pseudopotential and errors of calculation are discussed.