bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of intense laser irradiation on the structural stability of 3C-SiC
Authors: Deng Fa-Ming  , Gao Tao  , Shen Yan-Hong  , Gong Yan-Rong  ,   Mathematics Department, Sichuan University for Nationalities, Kangding 626001, China;,   Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, China
Published: December 2020

Using the linear response method based on the density functional perturbation theory, we simulate the effect of intense laser irradiation on the zinc-blende structural stability of silicon carbide crystal. By calculating the phonon dispersion curves for the 3C-SiC crystal of the zinc-blende structure at different electronic temperatures, we find that the transverse acoustic phonon frequencies of 3C-SiC become imaginary as the electron temperature increases. The critical electronic temperature is 3.395 eV. This means that the lattices of 3C-SiC become unstable under the intense laser irradiation. These results are very similar to the previous results for the diamond structure(C and Si) and the zinc-blende structure (GaAs and InSb). In an electron temperature range of 0-4.50 eV, the LO-TO splitting at Γ gradually increases with the increase of electronic temperature. When the electron temperature is beyond 4.50 eV, the splitting decreases. The results indicate that only under the intense enough laser irradiation, the ionic strength can be weakened by the electronic excitation.
Thermomagnetic power generation of Mn1.2Fe0.8P1-xSix compounds in strong field of permanent magnet
Authors: Liu Zhong-Shen  , Tegus O  , Ou Zhi-Qiang  , Fan Wen-Di  , Song Zhi-Qiang  , Ha Si Chao Lu  , Wei Wei  , Han Rui  ,   Inner Mongolia Key Laboratory for Physics and Chemistry of Functional Materials, Inner Mongolia Normal University, Hohhot 010022, China;,   No.8 High School of Dehui, Dehui 130323, China
Published: December 2020

In this paper, we study the thermomagnetic power generation performances of compound series Mn1.2Fe0.8P1-xSix in a strong magnetic field of permanent magnet. The compounds are synthesized by using the high-energy ball milling and solid state reaction method. The crystalline structures, magnetic properties, and the thermomagnetic power generation performances of the compound series Mn1.2Fe0.8P1-xSix are measured. The results show that Mn1.2Fe0.8P0.37Si0.63 and Mn1.2Fe0.8P0.35Si0.65 are the compounds of a first-order phase transition and the soft ferromagnetic materials, and they are of Fe2 P-type hexagonal structure, Curie temperatures of these compounds are 334 K and 348 K in the industrial waste heat temperature zone. According to this feature that temperature variation of the first-order phase transition material leads to a large change of magnetization at the Curie temperature, we design a demonstration device for thermomagnetic generator, and measure the relationships of induction current generated in ferromagnet phase transition with the coil turn number, mass and surface area of thermomagnetic generator material, and the gradient of surface temperature for compounds Mn1.2Fe0.8P0.37Si0.63 and Mn1.2Fe0.8P0.35Si0.65. The results show that the Mn1.2Fe0.8P1-xSix compound series possess the high performances of thermomagnetic power generation, and they are expected to be candidates of magnetic materials for thermomagnetic power generation.
Mutual compensation property of electrooptic and magnetooptic effects and its application to sensor
Authors: Li Chang-Sheng  ,   Department of Optoelectronics Engineering, School of Instrumentation Science and Optoelectronics Engineering, Beihang University, Beijing 100191, China
Published: December 2020

Mutual compensation property between electrooptic and magnetooptic modulations in a crystal with electrooptic and magnetooptic effects and its application to magnetooptic sensor are investigated theoretically and experimentally. Under the condition of light intensity modulation, electrooptic and magnetooptic modulation effects can compensate for each other, so that the transmitted light intensity through the crystal can be kept at a certain fixed value. Based on this mutual compensation property, a novel optical current (or magnetic field) sensor is proposed and demonstrated experimentally by use of a single bismuth germanate (Bi4Ge3O12, BGO) crystal. The optical sensing unit is composed mainly of two polarizers and a block of BGO crystal with the shape of parallelogram. The BGO crystal itself can produce an optical phase bias of π/2, and it can be used as both a current sensing element and an electrooptic compensator. The change of magnetooptic rotation angle through the crystal can be compensated in real time by the change of electrooptic phase retardation caused by the applied voltage, thus the closed-loop optical measurement of current (or magnetic field) can be achieved. The 50 Hz ac current within 5 A is measured experimentally. The required compensating ac voltage is about 21.2 V/A in root-mean-square value. Experimental data show a good linear relationship between measured current and compensating voltage, and the nonlinear error is less than 1.7%.
Chaos control and anti-control in Boost converter based on altering correlation
Authors: Zhang Fang-Ying  , Hu Wei  , Chen Xin-Bing  , Chen Hong  , Tang Xiong-Min  ,   Lab Center, Guangzhou University, Guangzhou 510006, China;,   Faculty of Automation, Guangdong University of Technology, Guangzhou 510006, China
Published: December 2020

Chaos control and anti-control are one pair of inverse problems. In this paper, the correlation of system state variables is investigated, and the method of realizing the chaos control and anti-control of system under the condition of variation of correlation coefficients of current controlled continuous current mode Boost converter is analyzed. The above these lay the theoretical foundation for practical applications. Discrete-time model of system is established. The mechanisms of chaos control and anti-control in Boost converter are theoretically explained by monodromy matrix theory. The research results indicate that only when the correlation coefficient of system is changed, the Boost converter can be controlled from any state to period 1, 2, 4 orbits or chaotic state, which means that the output of the system can realize chaos control and anti-control. Simulation results verify the analysis results.
Load-induced cascading failure in interdependent network
Authors: Peng Xing-Zhao  , Yao Hong  , Du Jun  , Wang Zhe  , Ding Chao  ,   Aeronautics and Astronautics Engineering College, Air Force Engineering University, Xi'an 710038, China;,   Science College, Air Force Engineering University, Xi'an 710051, China
Published: December 2020

The study of load-induced cascading failures in interdependent networks is of great realistic significance, which can provide valuable reference for designing high robust interdependent network or improving their robustness. In this paper, we establish a cascading model for a double layer interdependent network, and study the effects of the contributions of inter-degree and intra-degree to the loads, the coupling, and the intra-node linking similarity on the cascading failure in the interdependent network. Our studies show that when the contributions of inter-degree and intra-degree to the loads attain some values, the interdependent network reaches the highest robustness against cascading failures. As a notable feature for the interdependent network that is different from an isolated network, the coupling must have a significant influence on cascading failure in the interdependent network. In order to reach higher robustness, we suggest that the disassortative coupling be used and the inter-degree be made as homogeneous as possible under condition that a larger average inter-degree is adopted. In addition, we find that it is contrary to the case of neglecting loads that when the Pearson correlation coefficient for measuring the intra-layer degree-degree relation is larger, the interdependent network is more robust against cascading failures.
The model of interdependent network based on positive/negativecorrelation of the degree and its robustness study
Authors: Chen Shi-Ming  , Lü Hui  , Xu Qing-Gang  , Xu Yun-Fei  , Lai Qiang  ,   School of Electrical and Electronic Engineering, East China Jiaotong University, Nanchang 330013, China
Published: December 2020

The model of interdependent network based on positive/negative correlation of the degree is constructed by the typical Barabási-Albert network in this paper. Dependency modality and dependency degree are considered in the model. Two parameters F and K are defined, which represent the proportion of dependency node and the redundancy of dependency, respectively. We study the influences of different values of F and K on the robustness of interdependent network in cascading failures under degree-based attacks and random attacks and also compare the results with those from the random interdependent network model. The simulation results show that the robustness of both random independency and interdependent network based on positive/negative correlation of the degree decreases as F increases and increases as K increases; in the model of full interdependence (F = 1), the robustness of interdependent network based on positive correlation of the degree is optimal under random attacks; the interdependent network based on negative correlation of the degree shows stronger robustness in the model of partial interdependence (F= 0.2, 0.5, 0.8). While the interdependent network based on positive correlation of the degree shows poorer robustness with any value of F under degree-based attacks.
Performance evaluation of the simulated daily average temperature series in four seasons in China by Beijing Climate Center climate system model
Authors: Zhao Shan-Shan  , He Wen-Ping  ,   National Climate Center, China Meteorological Administration, Beijing 100081, China
Published: December 2020

In the present paper, the detrended fluctuation analysis (DFA) method is first used to analyze the daily average temperature records in four seasons in China, and the results show that the seasonal temperature records exhibit long-range correlation in China, especially in Xinjiang and Xizang in western China. Based on the long-range correlation in observational temperature records, we use DFA to evaluate the performances of the simulated daily average temperature series in four seasons in China by Beijing Climate Center climate system model (BCC_CSM) (1.1 m), and find that the BCC_CSM (1.1 m) can reflect the long-range correlations in different seasons. In general, the simulated results are best in spring except for the bad performance in Jiangnan. In summer, the simulation performance is poor in middle-east China and most areas in Tibet, especially in the southern North China, western Huanghai, Jiangnan and South China. The long-rang correlation of the simulated data for autumn is stronger in Northeast China, southeast North China, while weaker in the most of Northwest China. In winter, except for the eastern seaboard, the simulated long-range correlations of daily temperature are weaker than that of observational records in most China. And the simulated performance is poor in Northwest China, Southwest China, northern South China, southern Jiangnan and northern Northeast China, especially in the western Tibet.
Improvement and adaptability evaluation of standardized precipitation evapotranspiration index
Authors: Zhao Jing  , Yan Deng-Hua  , Yang Zhi-Yong  , Hu Yong  , Weng Bai-Sha  , Gong Bo-Ya  ,   Environmental Science and Engineering Department, Donghua University, Shanghai 201620, China;,   Water Resources Department, China Institute of Water Resources and Hydropower Research, Beijing 100038, China;,   Anhui and Huaihe River Water Resources Research Institute, Hefei 230088, China
Published: December 2020

In view of the question about larger estimate error in arid areas by using the Thornthwaite method of estimating potential evaporation in the process of calculating standardized precipitation evapotranspiration index, we use the FAO Penman-Monteith method instead of Thornthwaite method to improve the method of calculating the standardized precipitation evapotranspiration index. Based on the 1961-2013 daily meteorological data offered by 541 stations of Meteorology Bureau, the distribution of test and standardized rainfall index, Palmer drought severity index and soil moisture are used to analyze the consistency with standardized rainfall evaporation index when used to evaluate drought in the applicability of area and season. Result shows that the improvement on the method of evaporation capacity calculation can significantly expand the application of standardized precipitation evapotranspiration index in area and season, making standardized precipitation evapotranspiration index applied to national drought assessment well, making up the shortcomings in the applicability of standardized precipitation evapotranspiration index in winter at a short time scale level in arid region. In addition, both yearly time scale and monthly time scale of drought assessment ability about modified standardized precipitation evapotranspiration index are improved, meeting the demand for drought assessment in our country, which is given priority to seasonal drought.
Asynchronous stabilization of switched systems: Adjacent mode-dependent average dwell time
Authors: Wang Yue-E  , Wu Bao-Wei  , Wang Rui  ,   College of Mathematics and Information Science, Shaanxi Normal University, Xi'an 710119, China;,   School of Aeronautics and Astronautics, Dalian University of Technology, Dalian 116024, China
Published: December 2020

This paper addresses the stabilization problem of a class of switched linear systems. Due to the presence of switching delay in the switching signal of the controller, the switching of the controller and the of the system are turned out to be asynchronous. By combining switching signal method with the multiple Lyapunov function method, some sufficient conditions are provided to guarantee the stability of the whole switched system by an adjacent mode-dependent average dwell time scheme. These conditions imply the relationship among the continuous dynamics, switching delay, and the average dwell time. Finally, a numerical example is presented to illustrate the effectiveness of the proposed method.
Design of shared aperture metamaterial and its applications for high gain and low radar cross section antenna
Authors: Li Wen-Qiang  , Cao Xiang-Yu  , Gao Jun  , Zheng Yue-Jun  , Yang Huan-Huan  , Li Si-Jia  , Zhao Yi  ,   School of Information and Navigation of AFEU, Xi'an 710077, China
Published: December 2020

A shared aperture metamaterial (SA-MTM) with partially reflection and absorber characteristics is presented. The SA-MTM is composed of two metallic layers separated by a dielectric spacer; the top absorbing surface (AS) consists of oblique cross metallic pattern loaded with lumped resistances, and the bottom partially reflecting surface (PRS) consists of etched parallel slots in a metallic layer. An SA-MTM with partial reflection and absorption characteristics is fulfilled by making the absorbing surface and partially reflecting surface shared the same aperture in the vertical direction. The SA-MTM is applied to the waveguide slot antenna; the Fabry-Perot resonance cavity constructed by the PRS and the metallic ground layer of the waveguide slot antenna can achieve high gain, while the AS can obtain the low radar cross section (RCS) characteristic antenna by absorbing the incident wave. Simulation and experimental results demonstrate that the antenna with SA-MTM gain is enhanced above 3 dB in the operation frequency range, the backscattering RCS is obviously reduced in a frequency range of 2–9 GHz. This idea can help us design a high gain and low RCS antenna, which overcomes the conflict between scattering and radiation performance of antenna.
Study on a zooming optical system based on simple lens array used for laser uniform irradiation
Authors: Jiang Xiu-Juan  , Li Jing-Hui  , Zhu Jian  , Lin Zun-Qi  ,   School of Information Engineering, Guangdong University of Technology, Guangzhou 510006, China;,   Key Laboratory for High Power Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China;,   Shanghai Institute of Laser Plasma, Shanghai 201800, China
Published: December 2020

A zooming optical system based on a simple lens array used for uniform irradiation by a large-aperture laser is studied; and it can be shown that the size of target spot may be flexibly adjusted by changing the separation between the lens array and the focusing lens. How the choice of optical parameters will affect the zooming ability is analyzed, and a practical system is designed. Propagation of laser beam through the optical system is simulated numerically; results show that the spots in different size are similar in intensity structure. Speckle separation, modulation contrast, rms nonuniformity, and concentration ratio of the spot are quantified, and their variations are analyzed when the target is placed in different positions relative to the focal plane of the focusing lens.
A novel fast zooming scheme for direct-driven laser fusion
Authors: Zhong Zhe-Qiang  , Hu Xiao-Chuan  , Li Ze-Long  , Ye Rong  , Zhang Bin  ,   School of Electronic and Information Engineering, Sichuan University, Chengdu 610064, China
Published: December 2020

Illumination uniformity of a target is highly required to achieve central ignition in inertial confinement fusion based on direct-driven fusion. However, the shell may be compressed due to its interaction with laser beams during the laser pulse duration, and may further result in the degradation of illumination uniformity and the enhancement of the cross-beam energy transfer (CBET). Hence a novel fast zooming scheme for direct-driven laser fusion is proposed, i.e., by introducing the variable wavefront to the laser beam provided by a special-designed electro-optic crystal, thus the location and size of the focal spot could be controlled in real time, achieving the aim of improving the illumination uniformity and alleviating the CBET. This model of fast zooming has been built up, and variations of spot size and the radius of curvature of the additional spherical wavefront with time have been numerically simulated and analyzed based on the analysis of the interaction of the laser beam and the target. Results indicate that the fast zooming scheme could achieve effective and real-time control on the radius ratio between the focal spot and the target. Moreover, the fast zooming scheme has a little impact on the spatial filter capability and the third harmonic frequency conversion efficiency.
A theory for monitoring combustion of natural gas based on the maximum point in sound absorption spectrum
Authors: Zhang Ke-Sheng  , Chen Liu-Kui  , Ou Wei-Hua  , Jiang Xue-Qin  , Long Fei  ,   School of Information Engineering, Guizhou Institute of Technology, Guiyang 550003, China;,   School of Electrical and Information Engineering, Chongqing University of Science and Technology, Chongqing 404100, China;,   School of mathematics and computer science, Guizhou Normal University, Guiyang 550001, China;,   Institute of Intelligent Information Processing, Guizhou University, Guiyang 550025, China
Published: December 2020

Compositions of natural gases are different between each other because of different sources, resulting in the fact that natural gases have different energy contents and monetary value. This paper presents a theory to monitor the combustion properties of natural gas by using the acoustic relaxation phenomenon in which the maximum point of acoustic spectrum varies with gas composition. The theory is developed from the frequency-dependent sound absorption spectrum which can be reconstructed from its maximum point synthesized in the acoustic measurements at two frequencies. The theory uses the relation between the two values of the maximum point (i.e. the relaxation frequency and the maximum relaxational absorption) and gas composition to quantitatively monitor the gas. Moreover, the theory has the advantages of avoiding the detection of the gas density and the variation of the ambient pressure, which is necessary in the traditional way of measuring the maximum point of sound absorption spectrum.
A regular composite feature extraction method for vibration signal pattern recognition in optical fiber link system
Authors: Li Kai-Yan  , Zhao Xing-Qun  , Sun Xiao-Han  , Wan Sui-Ren  ,   National Research Center for Optical Sensing/Communications Integrated Networking, Biological Science & medical Engineering, Southeast University, Nanjing 210096, China
Published: December 2020

Phase optical time-domain reflectometer link monitoring system is a kind of sensor system which uses optical fiber as sensing medium. It can detect, recognize and locate invasive signals. The module of pattern recognition, which is one of the important parts of the system, can intelligently and instantly distinguish dangerous intrusions from safe disturbances. This paper proposes a regular composite feature extraction method which can be used for vibrational signal pattern recognition in an optical fiber monitoring system. This method applies an improved double-threshold method to detect the start-stop positions of the valid signal segments, and then combines the maximum energy and maximum signal noise ratio to select the main invasion feature segment within a sampling period. The composite eigenvectors, which are extracted by using the last time of the feature segment and wavelet packet energy spectrum, can be used by the support vector machine to recognize the signal patterns. Experiment results show that the accuracy rate of the pattern recognition has been improved significantly based on the proposed method in this paper.
Study on the effect of peak stress on dynamic damage evolution of high pure copper
Authors: Pei Xiao-Yang  , Peng Hui  , He Hong-Liang  , Li Ping  ,   Key Laboratory of Shock Wave and Detonation Physics, Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang 621900, China;,   State Key Laboratory of Explosion and Technology, Beijing Institute of Technology, Beijing 100081, China
Published: December 2020

Effects of peak stress on the properties of dynamic damage evolution of oxygen free high-pure copper (OFHC) are investigated. The spall fracture experiments are conducted in gas gun, and the damage evolution process is studied using the time-resolved free-surface velocity interferometry, also the post-experiment metallurgical analysis of the soft-recovered samples. It is indicated that, with the increase of peak stress, the spall strength has little changed, but distinct differences are observed in the magnitude and rate of damage at which the velocity rises to the first peak beyond the minima, and the rate of damage evolution increases remarkably. It is concluded that the peak stress is not sensitive to the nucleation of voids, but is one of the most important factors for the growth of voids.
Drops on microstructured surfaces: A numerical study using many-body dissipative particle dynamics
Authors: Wang Yu-Xiang  , Chen Shuo  ,   School of Aerospace Engineering and Applied Mechanics, Tongji University, Shanghai 200092, China
Published: December 2020

Because of their ability of self-clean, superhydrophobic surfaces have received substantial attention for years especially in surface science field. In this paper, the drop's wettability on different rough surfaces is simulated by using many-body dissipative particle dynamics (MDPD) and a contrast with the Cassie-Baxter theory's predictions is made. A combination of short-range repulsive and long-range attractive forces is used as wall-fluid interaction to generate different wettability, and a simple but efficient numerical method is introduced to measure the contact angle. The simulation could capture the static and dynamic properties of drop on textured surfaces, it is also shown that the microstructured surfaces can pin the three-phase (solid-liquid-vapour) contact line and this phenomenon has also been observed by other researchers in their physical experiments, suggesting that people should be careful when using the Cassie-Baxter theory. An analysis was given about energy transformation between kinetic energy and surface energy. The simulated results also show that the low Φs can cause the drop to rebound easily under the same impact velocity.
Tunneling spectra for quantum wire/iron-based superconductor junction
Authors: Zhao Jing-Long  , Dong Zheng-Chao  , Zhong Chong-Gui  , Li Cheng-Di  ,   School of Sciences, Nantong University, Nantong 226019, China;,   School of Physical Sciences and Technology, Suzhou University, Suzhou 215006, China
Published: December 2020

Taking into account the interface scattering effect on each band (in-band interaction) and the interaction between the bands (inter-band interaction), within an extended Blonder-Tinkham-Klapwijk scattering formalism, we have studied the quasi-particle transport coefficients and the tunneling spectrum for quantum wire/iron-based superconductor junction of different types of two-level system by solving the Bogoliubov-de Gennes equations. It has been shown that: 1) When the junction is in ballistic limit, the platform near zero bias of the s -wave tunneling spectroscopy will become a conductance peak as the inter-band interaction increases, while a dip occurs in s++ -wave tunneling spectroscopy, and the zero-bias conductance peak will be depressed for p-wave. 2) When the interface scattering effect is not zero, the peaks in the two energy gaps of both s -wave and s++ -wave iron-based superconductor will be depressed; as the inter-band interaction increases, the dip between the two peaks will increase, moreover, the value of zero-bias conductance peaks for p-wave will be lowered and the value of nonzero-bias conductance will be increased. 3) As the in-band interaction is increased, the self-conductance peak will become sharper, while the another conductance peak is not only lowered but also smoothed. These results will be helpful for clarifying the structure of the pair-potential in iron-based superconductor and distinguishing their types.
Collagen network and the mechanical microenvironment of cancer cells
Authors: Sun Bo  ,   Department of Physics, Oregon State University Corvallis, OR, 97331
Published: December 2020

Mechanical interaction between cancer cells and their microenvironment plays a central role in the progression of tumors. In vitro models based on biopolymer networks have been successfully employed to simulate the 3D extracellular matrix (ECM) of tumors. In this review, we focus on type I collagen gel. We describe the hierarchical structural and mechanical properties of type I collagen ECM. We demonstrate that corresponding to the scales of adhesion sites, single cells and cell colonies, the mechanics of the ECM is dominated by single fibers, fiber clusters and rheology of the whole fiber network. In the end, we discuss the limitations of reconstituted type I collagen as in vitro ECM.
Research on heart-sound graphical processing methods based on heart-sounds window function
Authors: Cheng Xie-Feng  , Li Wei  ,   College of Electronic Science and Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210003, China
Published: December 2020

Currently, the one-dimensional signal processing method for heart-sound analysis and recognition is the mainstream in researches. In order to gain more intuitive features in manifestation, to improve the effect of classification, and to endarge the heart-sound recognition field, this paper puts forward a heart-sound texture feature extraction and recognition algoriithm, which is based on heart-sound window function and the combination of heart-sound and image processing technology. Firstly, we give a heart-sound model, a definition of heart-sound time-frequency diagram, and a heart-sound texture map; we also discuss how to utilize heart-sound window function and short-time Fourier transform to obtain a two-dimensional heart-sound time-frequency diagram. After that, in the light of the characteristics of heart-sound, we mainly study the structure principle and implementation method of a heart-sound window function Finally, the heart-sound texture feature extraction and identification are realized by the improved pulse-coupled neural network model (IPCNN). Simulation experiments show that compared with the traditional window function, the heart-sound time-frequency diagram obtained using heart-sound window function has a clearer and noise well suppressed texture. Furthermore, compared with other three kinds of typical recognition methods, IPCNN has the lower computational cost and higher recognition rate. So, we can arrive at the conclusion that the method for heart-sound feature extraction and recognition based on image processing techniques is the effective one.
Photonic emission analysis of cipher chips based on time-correlated single-photon counting
Authors: Wang Hong-Sheng  , Ji Dao-Gang  , Gao Yan-Lei  , Zhang Yang  , Chen Kai-Yan  , Chen Jun-Guang  , Wu Ling-An  , Wang Yong-Zhong  ,   Department of Information Engineering, Ordnance Engineering College, Shijiazhuang 050003, China;,   Laboratory of Optical Physics, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China;,   Hebei Normal University, Shijiazhuang 050018, China
Published: December 2020

When in operation, cipher chips emit photons which can reveal important information about their operation and data. An experimental system based on single-photon counting for the detection, transmission, processing and analysis of photonic emission from CMOS semiconductor integrated circuits has been designed and constructed. Using time-correlated single-photon counting (TCSPC) technology, we have analyzed the photon emission of cipher chip AT89C52, and measured the relationship between its emission intensity and voltage. We have also analyzed in detail the relationship between the photonic emission and the operations and data processed in the chip at the instruction level. Furthermore, we have confirmed the feasibility of our TCSPC technique using an oscilloscope. Our experimental results show that cipher chip photonic emission analysis based on TCSPC technology is a relatively low cost but effective method for optical side-channel attacks, and that it poses a serious practical threat to cipher chip security.
Ground state of a two-component dipolar Bose-Einstein condensate confined in a coupled annular potential
Authors: Zhang Xiao-Fei  , Zhang Pei  , Chen Guang-Ping  , Dong Biao  , Tan Ren-Bing  , Zhang Shou-Gang  ,   Key Laboratory of Time and Frequency Primary Standards, National Time Service Center, Chinese Academy of Sciences, Xi'an 710600, China;,   Information Technology Center, Honghe University, Mengzi 661100, China;,   Department of Physics, School of Mathematics and Physics, Chongqing University of Science and Technology, Chongqing 401331, China
Published: December 2020

By using the imaginary-time propagation method, we study the ground state structure of a two-component dipolar Bose-Einstein condensate confined in a coupled annular potential. The effects of contact and dipole-dipole interaction on the ground state density distribution of such a system are investigated in detail. The results show that the dipole-dipole interaction, acting as a new degree of freedom, can be used to obtain the desired ground state phases, and to control the phase transition between different ground states.
Stochastic P-bifurcations in tri-stable van der Pol-Duffing oscillator with multiplicative colored noise
Authors: Wu Zhi-Qiang  , Hao Ying  ,   Department of Mechanics, Tianjin University, Tianjin 300072, China
Published: December 2020

This article aims at studying the stochastic P-bifurcation of tri-stable van der Pol-Duffing oscillator subjected to multiplicative colored noise. First, the stationary probability density of amplitude is derived by using the stochastic averaging method. Then the critical parameter conditions of stochastic P-bifurcation are obtained based on the singularity theory. And the different types of stationary probability densities of amplitude are also obtained, which are in good agreement with the results from Monte-Carlo numerical simulation. Based on these results, the effects of the noise correlation time, noise intensity and linear damping coefficient on the P-bifurcation and the stable response behavior of the system are studied.
Control strategy and application of hysteretic chaotic neuron and neural network
Authors: Xiu Chun-Bo  , Liu Chang  , Guo Fu-Hui  , Cheng Yi  , Luo Jing  ,   Key Laboratory of Advanced Electrical Engineering and Energy Technology, Tianjin Polytechnic University, Tianjin 300387, China;,   School of Electrical Engineering and Automation, Tianjin Polytechnic University, Tianjin 300387, China
Published: December 2020

In order to remain the structure of the neural network in the process of the optimization unchanged, taking the hysteretic chaotic neuron and the hysteretic chaotic neural network as controlled plants, a novel control strategy based on the filtered tracking error is proposed to perform the stability control for the single hysteretic chaotic neuron or the hysteretic chaotic neural network. Especially, the hysteretic chaotic neuron and the hysteretic chaotic neural network can be used to solve the optimization problem through using the control strategy on condition that the generation mechanisms of the nonlinear characteristics, hysteresis and chaos, are unchanged. The control law is composed of two terms: one is the equivalent control term in the ideal filtered tracking error surface, and the other is the control term which can make the system reach the filtered tracking error surface quickly. Lyapunov stability method is used to prove the stability of the control strategy for the single hysteretic chaotic neuron and hysteretic chaotic neural network. The control laws of hysteretic chaotic neurons can be obtained according to the optimization function. The state of the single hysteretic chaotic neuron or the hysteretic chaotic neural network can converge to an extreme point of the optimization function gradually by the control law. In this way, the optimization problem can be solved effectively. Simulation results prove the feasibility and validity of the control strategy for optimization problem.
Simulation of pedestrian push-force in evacuation with congestion
Authors: Zhang Lei  , Yue Hao  , Li Mei  , Wang Shuai  , Mi Xue-Yu  ,   MOE Key Laboratory for Urban Transportation Complex Systems Theory and Technology, Beijing Jiaotong University, Beijing 100044, China;,   School of Civil and Architectural Engineering, Hebei United University, Tangshan, 063009 China
Published: December 2020

The simulation of pedestrian push-force in evacuation with arched congestion before exit is presented based on cell automata. The generation, absorption, transfer and gather of pedestrian push-force are analyzed. Initial push-force facing to exit is generated based on the distance between pedestrian and exit. The scalar and vector sum of push-force are introduced to respectively describe the push effect and resultant force of outside jam push-force in crowded evacuation. Absorption coefficient and anti-crush coefficient are introduced to respectively describe the ability for pedestrian to absorb and resist the outside jam push-force. Simulation results show that the increase of absorption coefficient or anti-crush coefficient can effectively prevent pedestrian from being injured. It is found that three phases: weak protection, strong protection and complete protection are distinguished based on two critical absorption coefficients and an anti-crush coefficient. Pedestrian casualties will increase with the number of evacuation pedestrian rising. It is also shown that pedestrian casualties in jam occur in a reverse bell-shape symmetry zone before exit.
Analytical model of electrostatic force generated by edge effect of a Kelvin capacitor based on conformal transformation
Authors: Li Shi-Song  , Zhang Zhong-Hua  , Zhao Wei  , Huang Song-Ling  , Fu Zhuang  ,   Department of Electrical Engineering, Tsinghua University, Beijing 100084, China;,   National Institute of Metrology, Beijing 100029, China
Published: December 2020

We present a new realization of weak electrostatic force based on Kelvin capacitor, which, compared with the conventional realization, simplifies the mechanical design without synchronously moving the central and guard-ring electrodes. However, a residual force due to the edge effect of the capacitor should be accurately known. In this paper, an analytic model of the electrostatic force generated from the edge effect is presented based on conformal transformations. The accuracy of the model is verified by the finite element calculation based on a micro-Newton weak force generation.
Spectrum of UN2 under inner radiation fields
Authors: Xie An-Dong  , Xie Jing  , Zhou Ling-Ling  , Wu Dong-Lan  , Ruan Wen  , Luo Wen-Lang  ,   School of Mathematics and Physics, Jinggangshan University, Ji'an 343009, China;,   School of Electrical and Control Engineering, Xi'an University of Science and Technology, Xi'an 710054, China
Published: December 2020

A density functional method DFT/B3P86 with relativistic effective core potential basis for U and 6-311+G(d) basis for N is used to study the energy gap and harmonic frequency of UN2 ground state molecule under the action of the uranium-produced spontaneous radiation fields ranging from -0.005 to 0.005 a.u.. The results show that UN2 has an anti-symmetry expansion vibrational frequency ν3 (σg) that is close to experimental value 1051.1 cm-1 under the action of different spontaneous radiation fields, and a symmetrical expansion vibrational frequency ν1(σg) that is close experimental value 1008.3 cm-1. The energy gap is found to decrease with increasing the spontaneous radiation field. The electron which occupies an orbital is easy to excite to empty orbital and transform into an excited state. The UN2 molecule turns unstable in the spontaneous radiation field; N2, O2 and others more easily diffuse into the surface interior, thus corroding the uranium surface and aggravating the corrosion of uranium in the spontaneous radiation field.
High-repetition-rate passively mode-locked erbium-doped all fiber laser
Authors: Dou Zhi-Yuan  , Tian Jin-Rong  , Li Ke-Xuan  , Yu Zhen-Hua  , Hu Meng-Ting  , Huo Ming-Chao  , Song Yan-Rong  ,   Institute of Information Photonics Technology, College of Applied Sciences, Beijing University of Technology, Beijing 100124, China;,   Chinese People's Armed Police Force Academy, Langfang 065000, China;,   Tianjin Institute of Modern Laser Optics Technology, Tianjin 300190, China
Published: December 2020

We demonstrate a high-repetition-rate Er-doped all fiber laser with nonlinear-polarization-rotation mode-locking. The highest repetition rate of the laser is 217 MHz. The fiber laser has a very simple and compact structure and can output a stable mode-locking pulse only by using one polarization-dependent isolator and a polarization controller. The pulse width, spectral width and signal-to-noise ratio are measured to be 69 fs, 56 nm and 76 dB respectively.
Effects of quantum confinement and symmetry on the silicon photonic crystal band gap
Authors: Zhou Nian-Jie  , Huang Wei-Qi  , Miao Xin-Jian  , Wang Gang  , Dong Tai-Ge  , Huang Zhong-Mei  , Yin Jun  ,   Institute of Nanophotonic Physics, Guizhou University, Guiyang 550025, China
Published: December 2020

Photonic crystal not only can be used to inhibit the spontaneous emission and redistribute the energy into useful forms, but also can be designed to control and confine photons. Since the concept was introduced by John and Yablonovitch in 1987, there have been discussed the machinery of broadening the band bap and a quest for the optimal structure. Band structures of two-dimensional photonic crystals with different lattices and scatters of air hole of various shapes, orientations and sizes are investigated by the plane wave expansion method. The calculation results suggest that the variation of the photonic crystal band bap is attributed to the competition between symmetry and quantum confinement effects.
Physical mechanism of super-broadband and all-angle self-collimation transmission in photonic crystal with low rotational symmetry
Authors: Liang Wen-Yao  , Zhang Yu-Xia  , Chen Wu-He  ,   School of Physics and Optoelectronics, South China University of Technology, Guangzhou 510640, China
Published: December 2020

We propose a two-dimensional photonic crystal structure with low rotational symmetry and investigate its band structure characteristics over the whole first Brillouin zone by the plane wave expand method. The physical mechanism of broadband all-angle self-collimation effect and the influence of aspect ratio on the bandwidth are clarified. Furthermore, we obtain the existence criterion for self-collimation modes covering almost the whole fourth band for TE polarization. Especially, there exist two wide flat regions spanning over the first Brillouin zone which exhibit unique properties: one dimension corresponds to broad band from 0.47 to 0.53 (2πc/a), while the other corresponds to all incident angles of 0°–90°. Based on the above unique properties, the broadband all-angle self-collimation propagation with a bandwidth of 187 nm around 1550 nm is demonstrated by the finite-difference time-domain method.
Characteristics of the geometrical scattering waves from underwater target in fractional Fourier transform domain
Authors: Li Xiu-Kun  , Meng Xiang-Xia  , Xia Zhi  ,   Acoustic Science and Technology Laboratory, Harbin Engineering University, Harbin 150001, China;,   College of Underwater Acoustic Engineering, Harbin Engineering University, Harbin 150001, China
Published: December 2020

The components of the underwater target scattering waves alias together in time domain and frequency domain realistically. They are affected by the incident angle, and show great differences under different angles. It is necessary to build an analytical model of scattering waves under all-direction incident angles theoretically. The analytical expressions of geometrical scattering components changing with the incident angle in fractional Fourier transform domain are deduced in this paper. The all-direction model in optimal fractional Fourier transform domain of the scattering waves is built. Based on this, the geometrical feature of underwater target echo is provided. In addition, the relationships between the resolution and the bandwidth of transmitted signal, and between the calculation accuracy and the length of observational signal are given. By processing experimental data, it is indicated that the model in fractional Fourier transform domain is in accordance with the characteristics of underwater target. It can provide a theoretical basis for target recognition under unknown incident angle.
Fine structures and characteristics on supersonic flow over backward facing step with tangential injection
Authors: Zhu Yang-Zhu  , Yi Shi-He  , Kong Xiao-Ping  , He Lin  ,   College of Aerospace Science and Engineering, National University of Defense Technology, Changsha 410073, China
Published: December 2020

The fine flow structure over backward facing step with supersonic injection at the free-stream Mach number of 3.4 is investigated via nano-tracer planar laser scattering (NPLS). The Mach number of injection is measured to be 2.45 actually, even though designed to be 2.5 nominally. The shock wave, shear layer, mixing layer, Kelvin-Helmholtz vortex, horn-like vortex, coherent structures, etc, are clearly revealed. Flow images with the high spatiotemporal resolution are captured involving the streamwise and spanwise flow field in planes at different heights. Based on a large number of fine images, the spatial correlation analysis is conducted to reveal the structure scale and incline angle. The results indicate that with the flow developing, the structure angle tends to be larger and the structure scale becomes smaller. While the injection is working, the downstream surface of step will be covered by a thin film layer. In addition, the schlieren technique is used to compare with NPLS results, and the surface pressure coefficients are measured. In the downstream of injection, the coefficient is 0.0146. The fractal dimensions of different zones in NPLS image are calculated, showing that in the initial stage of flow the fractional dimension is approximate to 1 and the closer to downstream, the higher the dimension is.
Electronic structures and optical properties of boron and phosphorus doped β-Si3N4
Authors: Cheng Chao-Qun  , Li Gang  , Zhang Wen-Dong  , Li Peng-Wei  , Hu Jie  , Sang Sheng-Bo  , Deng Xiao  ,   MicroNano System Research Center, Key Laboratory of Advanced Transducers and Intelligent Control (Shanxi Province and Ministry of Education) and College of Information Engineering, Taiyuan University of Technology, Taiyuan 030024, China;,   College of Physics and Optoelectronics, Taiyuan University of Technology, Taiyuan 030024, China
Published: December 2020

The electronic structures and optical properties of boron/phosphorus mono- and co-doped β silicon nitride are studied by the first-principles plane-wave ultrasoft pseudopotential method with the generalized gradient approximation. The results are obtained as follows. The B-doped system has a better stability than the P-doped system, while the P-doped structure has a stronger ionicity. The mono-doping and co-doping can narrow the band gap of β silicon nitride while the co-doping introduces the deep impurity levels and strengthens the localized states. The mono-doping causes the imaginary part of dielectric function, the peaks of absorption spectra and energy loss spectra to red-shift, and their amplitudes to decrease, resulting in a significant difference from the intrinsic state. The co-doping induces the peak of imaginary part of the dielectric function to blue-shift, broadens the energy loss peak, greatly enhances the electronic transition in the high energy region, and controlling the ratio of the numbers of atoms (B and P) in co-doping can achieve a low charged defect concentration, implying its potential application in the field of microelectronics.
Effect of As pressure-modulated InAlAs superlattice on the morphology of InAs nanostructures grown on InAs/InAlAs/InP
Authors: Yang Xin-Rong  , Zhou Xiao-Jing  , Wang Hai-Fei  , Hao Mei-Lan  , Gu Yun-Gao  , Zhao Shang-Wu  , Xu Bo  , Wang Zhan-Guo  ,   Department of Physics and Electronic Engineering, Handan College, Handan 056005, China;,   Key Laboratory of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China;,   Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100080, China
Published: December 2020

InAs/InAlAs/InP(001) nanostructure materials are grown using solid-source molecular beam epitaxy equipment. Effect of As pressure-modulated InAlAs superlattice on the morphology of InAs nanostructure is investigated. The results show that As pressure-modulated InAlAs superlattice can suppress the quantum wires formation and results in quantum dot growth with a uniform size distribution. The analysis indicates that the morphology of InAs nanostructure is caused mainly by the anisotropic strain relaxation of InAlAs layers and the anisotropic surface migration of In adatoms.