bluuebunny/crossref_metadata_2025 huggingface dataset:
A constitutive model of metal rubber based on hysteresis property
Authors: Zhu Bin  , Ma Yan-Hong  , Zhang Da-Yi  , Hong Jie  ,   School of Jet Propulsion, Beihang University, Beijing 100191, China
Published: December 2020

Metal rubber (MR) material is a new-type of damping material. Its raw material and fabrication process have same unique features. Wire helix is considered as the unit cell geometry of MR. Combining cylindrical compression coil spring theory, a mechanical model is established for individual wire helix which is located in the horizontal or longitudinal direction. Three contact statuses are analyzed for the neighboring helixes and mechanical models are derived for these cases according to the Kulun model. The arrangement and the spatial distribution of the microelements are assumed to be located evenly and periodically inside the MR. A mathematic model is established to characterize the damping behavior of MR. It came from the unit cell geometry and the fabrication process of MR materials. It is easy to explain the mechanism of hysteresis loop and the nonlinear stiffness and damping characteristic of MR by analyzing contact states and contact number of unit cell wire helixes. Finally, a comparison is made between theoretical results and experimental results. This model is valuable for the analysis of the material mechanics and the design of MR. It provides theoretical support for the further engineering application of MR in the field of vibration reduction.
Synthesis and growth mechanism of high length-diameter ratio strip-shape diamond by HPHT
Authors: Hu Mei-Hua  , Ma Hong-An  , Yan Bing-Min  , Zhang Zhuang-Fei  , Li Yong  , Zhou Zhen-Xiang  , Qin Jie-Ming  , Jia Xiao-Peng  ,   State Key of Laboratory of Superhard Materials, Jilin University, Changchun 130012, China;,   Physical College, Inner Mongolia University for the Nationalities, Tongliao 028000, China
Published: December 2020

To extend the kind of diamond and solve the low life of diamond tools because of the insufficiency of holding force, the strip-shape diamond with more than 2.5 in length-diameter ratio and 0.81.0 mm in length is synthesized by optimizing FeNi based catalyst composition and using the technology in the China-type cubic anvil high pressure apparatus. Because of the unique morphology, the threshing phenomenon appearing in the using of diamond tools is controlled effectively. Furthermore, we find that the growth rate of strip-shape diamond is much faster than that of the conventional diamond. Strip-shape diamond morphology and catalyst composition around the growing diamond crystal are characterized by SEM and EDS. The results indicate that the facets of diamond crystal are elongated along {100} and {111} faces and catalyst compositions around the growing diamond crystal become segregated. On this basis, we illustrate the growth mechanism of strip-shape diamond.
Asymptotic solving method of soliton for El Nio/La Nia-southern oscillation nonlinear disturbed model
Authors: Lin Wan-Tao  , Chen Li-Hua  , Ouyang Cheng  , Mo Jia-Qi  ,   State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamic, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China;,   Department of Mathematics and Computer Science, Fuqing Branch of Fujian Normal University, Fuqing 350300, China;,   Faculty of Science, Huzhou Teachers College, Huzhou 313000, China;,   Department of Mathematics, Anhuii Normal University, Wuhu 241003, China
Published: December 2020

A class of El Nio/La Nia-southern oscillation (ENSO) stochastic disturbed model is considered. Firstly, using the special method of undetermined coefficients, the exact solution of the non-disturbed ENSO model is obtained. Then the approximate solutions of stochastic disturbed ENSO model are constructed by using the asymptotic theory and method. And it is illustrated with example that the asymptotic solutions have the better degree of accuracy.
Non-smooth bifurcation analysis of Chen system via impulsive force
Authors: Jiang Hai-Bo  , Zhang Li-Ping  , Chen Zhang-Yao  , Bi Qin-Sheng  ,   School of Mathematics, Yancheng Teachers University, Yancheng 224002, China;,   Faculty of Civil Engineering and Mechanics, Jiangsu University, Zhenjiang 212013, China
Published: December 2020

The complex dynamics of Chen system via impulsive force is investigated in this paper. The non-smooth bifurcation of Chen system via impulsive force is analyzed. The system can evolve to chaos by the cascading of period-doubling bifurcations. Besides, the system can evolve to chaos immediately by saddle-node bifurcations from period solutions. Finally, the Floquet theory is used to explore the non-smooth bifurcation mechanism for the periodic solutions.
Performances of a boron-lined ionization chamber used in neutron/-ray mixed field of reactors
Authors: Chen Guo-Yun  , Xin Yong  , Huang Fu-Cheng  , Wei Zhi-Yong  , Lei Sheng-Jie  , Huang San-Bo  , Zhu Li  , Zhao Jing-Wu  , Ma Jia-Yi  ,   Department of Physics, Nanchang University, Nanchang 330031, China;,   Space Environment Center, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China;,   Department of Physics, Nanjing University, Nanjing 210093, China
Published: December 2020

Boron-lined ionization chambers (BLICs) have gradually become one of radiation detectors which are used to monitor the neutron/-ray mixed field with large flux around reactors in recent years. In this paper a BLIC with high sensitivity is fabricated and the internal structure is detailed. By using a weak current amplifier with an accuracy of fA, the leakage current of the BLIC is less than 1.0 pA when the high voltage is below 700 V; under the irradiation by the Am-Be neutron source, on the I-V curve of the BLIC there appears a current plateau with a length of 500 V and a slope of 3.7210-4 V-1; when the operating voltage is 400 V, the leakage current of the BLIC is 0.4 pA. Experiments show that neutron signal current measured by the BLIC depends on the relative position of the BLIC with repect to the radiation source; a maximum of 2.0 pA is obtained when the source is 8 cm away from the bottom of the hole in the paraffin moderator. Under the exposure by 137Cs and 90Sr,-ray signal current measured by the BLIC is 1.02.0 pA, but the current plateau is not obvious in-ray field. The neutron sensitivity of the BLIC reaches a level of 1.010-15 Acm2s and the-ray sensitivity reaches a level of 9.010-22 Acm2seV-1. The BLIC shows small leakage current, high sensitivity, and good plateau characteristics, which can be used to monitor the neutron/-ray mixed field around reactors.
Numerical simulation of X-ray ionization and atmospheric temporal evolutions with high-altitude nuclear explosions
Authors: Ouyang Jian-Ming  , Ma Yan-Yun  , Shao Fu-Qiu  , Zou De-Bin  ,   College of Science, National University of Defense Technology, Changsha 410073, China
Published: December 2020

The X-ray ionizations and the atmospheric temporal evolutions with different altitude nuclear explosions are numerically simulated in this paper. It is concluded that the density of electrons generated by X-ray ionization has a peak value at 100 ns after the X-rays have arrived, and the peak density reduced with the increase of distance from the stripped nucleus area. The life time of electrons is long, and increases with the distance from the stripped nucleus area. O+, O2+, N2+ are generated by X-ray ionization. The distance of X-ray ionization in atmosphere is within a few tens of kilometers. The peak density of explosion at 80 km high is larger than at 120 km high in the area close to stripped nucleus area, but the scenario is opposite in the area far from stripped nucleus area.
Research on linewidth characteristics and broadening mechanism of distributed feedback fiber laser
Authors: Ni Jia-Sheng  , Zhao Yan-Jie  , Wang Chang  , Peng Gang-Ding  , Liu Tong-Yu  , Chang Jun  , Sun Zhi-Hui  ,   Key Laboratory of Optical Fiber Sensing Technology of Shandong Province, Laser Institute, Shandong Academy of Sciences, Jinan 250014, China;,   School of Information Science and Engineering, Shandong University, Jinan 250010, China;,   School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney 2032, Australia
Published: December 2020

The linewidth characteristics of distributed feedback fiber laser (DFB-FL) is fully explored in this paper. The linewidth broadening effect of DFB-FL induced by self-pulsation, phase-shifted grating, especially lasing window, external disturbance, etc. are extensivly investigated in the paper based on the theoretical derivation and experiment. An effective linewidth compression method is proposed, and a self-injection system of DFB-FL comes up to reduce its linewidth from 35 kHz to less than 10 kHz.
Design and optimization of low-loss low-nonlinear high negative-dispersion photonic crystal fiber
Authors: Zhang Ya-Ni  ,   Department of Physics and Information Technology, Baoji College of Arts and Science, Baoji 721007, China
Published: December 2020

A novel hexangular lattice dual-concentric-core photonic crystal fiber is proposed, which is composed of a central defect core, an outer ring core by introducing small air-holes on the forth ring and double cladding circle air-holes along the direction of fiber length. Based on full vector finite element method with anisotropic perfectly matched layers, its dispersion, nonlinear, leakage loss and mode field are numerically investigated. Numerical results indicate that the proposed fiber shows higher negative dispersion tunable effect and stronger confinement ability of guided mode, which the leakage loss is close to 10-2 dBm-1. The wavelength for high negative dispersion value can be adjusted by artificially choosing the parameters of proposed fiber, i.e. , d1 and f. Both its dispersion and dispersion slope are negative, the dispersion slope values are between-1-6 pskm-1nm-2 over C band, and its negative dispersion value is-3400 pskm-1nm-1, the nonlinear coefficient is only 3.6 km-1W-1, and the corresponding area of mode field is 43 m2 at wavelength of 1.55 m, if the parameter is selected as =1.2 m, f=0.917, d1=0.515 m. Obviously, it has a good dispersion compensation, therefore it has admirable applications in the field of high-speed large-capacity high-power pulses long-distance communication system.
All-optical logic gates based on nonlinear polarization rotation in high nonlinear fiber
Authors: Wang Wen-Rui  , Yu Jin-Long  , Han Bing-Chen  , Guo Jing-Zhong  , Luo Jun  , Wang Ju  , Liu Yi  , Yang En-Ze  ,   School of Electronic and Information Engineering, Tianjin University, Tianjin 300072, China;,   School of Physics and Electronic Science, Shanxi Datong University, Datong 037009, China
Published: December 2020

A novel scheme to realize all-optical logic gates is proposed based on nonlinear polarization rotation (NPR) in high nonlinear fiber (HNLF). Two optical signals A and B together with a continuous wave are injected into the HNLF. Due to the optical power variation in HNLF, nonlinear birefringence will be induced between the two polarization axes. Both the optical signal and the continuous wave are filtered out at the output of HNLF. By controlling the optical power and the polarization of the optical signal as well as the polarization of the polarizer with respect to the polarization of optical signal/continuous wave, multiple all-optical logic gates can be realized. The theoretical analysis of the optical logic gates based on NPR in HNLF is provided. And the feasibility of the scheme is demonstrated by realizing all opticaland,not,or,xor,nxor,A B,AB, half-adder and half-subtracter at 10 Gbit/s operation.
The phase diagram of the Gauss model on a decorated square lattice
Authors: Sun Chun-Feng  ,   School of Physics and Electronic Information Engineering, Xiaogan University, Xiaogan 432000, China
Published: December 2020

Using equivalent transformation and spin-rescaling methods, the Gauss model on a decorated square lattice is studied. It is found that the square decorated Gauss lattice could be transformed into a regular square Gauss lattice with nearest-neighbor, and next-nearest-neighbor interactions. By calculating the regular square-lattice Gauss model, the critical temperature of the Gauss model is obtained on a decorated square lattice, and the exact phase diagram of this system can also be obtained.
Influence of optical-phonon scattering on electron mobility in wurtzite AlGaN/AlN/GaN heterostructures
Authors: Yang Fu-Jun  , Ban Shi-Liang  ,   School of Physical Science and Technology, Inner Mongolia University, Hohhot 010021, China
Published: December 2020

Adopting a numerical method of solving self-consistently the Schrdinger equation and Poisson equation through taking into account the realistic heterostructure potential, which includes the influences of energy band bending and the finite thickness of barriers, and through considering the built-in electric field induced by spontaneous and piezoelectric polarization, the eigenstates and eigenenergies of electrons in two-dimensional electron gas (2DEG) are obtained for wurtzite AlxGa1-xN/AlN/GaN heterostructures with an inserted AlN layer. Based on the continuous dielectric model and the Loudon's uniaxial crystal model, optical-phonon modes and their ternary mixed crystals effect are discussed using the transfer matrix method. Furthermore, the Lei-Ting balance equation is extended in order to investigate the distribution of 2DEG and its size effect as well as ternary mixed crystals effect on electron mobility, which under the influence of each branch of optical-phonon modes are analyzed at room temperature. The results show that the increases of the thickness of inserted AlN layer and the Al component of AlxGa1-xN in the barrier enhance the built-in electric field in the GaN layer, leading 2DEG to be much closer to the interface of a heterostructure. In addition, it can also be found that the scattering from the interface phonons is stronger than from other optical-phonons, the interface phonons play a dominant role in the total mobility. A higher electron mobility can be obtained by adjusting appropriately the thickness of inserted AlN layer and Al component.
Nonlinear Landau-Zener transition of Fermi superfluid gases
Authors: Wang Wen-Yuan  , Meng Hong-Juan  , Yang Yang  , Qi Peng-Tang  , Ma Yun-Yun  , Ma Ying  , Duan Wen-Shan  ,   Key Laboratory of Atomic and Molecular Physics and Functional Materials of Gansu Province, College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070, China
Published: December 2020

By using the analysis of phase, fixed point and tunneling rate between two wells, we study the nonlinear Landau-Zener transition of Fermi superfluid gases in a two-mode system. We find that the interaction between fermi pairs can affect the quantum transition. We also find that when the interaction parameter c is less than the critical value c*, in the adiabatic limit, the quantum adiabatic transition theorem is still satisfied, but when the interaction parameter c is greater than this critical value, the quantum adiabatic transition theorem will not be satisfied. Finally, we obtain the relationship between the tunneling rate and the scan rate by comparing with the linear case.
The mechanism of negative magnetoresistance in nondegenerate p-type Hg1-xMnxTe (x0.17) monocrystal
Authors: Zhu Liang-Qing  , Lin Tie  , Guo Shao-Ling  , Chu Jun-Hao  ,   State Key Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083, China
Published: December 2020

It is important to study the mechanism of negative magnetoresistance (MR) in magnetic semiconductors for the correct understanding of the sp-d interactions between carriers and magnetic ions. In this work, temperature-dependent Hall effect (10300 K) and magnetic susceptibility (5300 K) are measured for the study of negative MR and paramagnetic enhancement of nondegenerate p-type Hg1-xMnxTe (x0.17) monocrystal. As temperature decreases, both negative MR and susceptibility show the same behaviors, each of which contains an exponentially changing temperature function \exp(-K/T). According to the theory of impurity energy level in semimagnetic semiconductor, magnetic field can lead to the spin-splitting of acceptor level and result in reducing the binding energy of acceptors, which is responsible mainly for the negative MR in nondegenerate p-type Hg1-xMnxTe monocrystal.
Study of the effect of lithography deviation on 4H-SiC floating junction junction barrier Schottky diode
Authors: Tang Xiao-Yan  , Dai Xiao-Wei  , Zhang Yu-Ming  , Zhang Yi-Men  ,   Key Laboratory for Wide Band-gap Semiconductor Materials and Devices of Ministry of Education, School of Microelectronics, Xidian University, Xi'an 710071, China
Published: December 2020

The breakdown voltage of 4H-SiC junction barrier schottky diode with floating junction is larger than that of traditional junction barrier Schottky diode under the condition of the same fixed on-resistance. It is a crucial technology that the alignment of lithography between p+ region of floating junction and main junction. The simulation results obtained using two-dimensional simulator ISE show that the breakdown voltage obviously drops with the deviation of lithography increasing. Although the breakdown characteristics of the dislocation and the alignment structure are similar, the series resistance of the dislocation structure is larger than the latter when the forward voltage is larger than 2 V.
Investigation of spectral regulation in dual- wavelength light-emitting diodes by using the selective p-doped barriers
Authors: Chen Jun  , Fan Guang-Han  , Zhang Yun-Yan  ,   Institute of Opto-Electronic Materials and Technology, South China Normal University, Guangzhou 510631, China;,   Experimental Teaching Center, Guangdong University of Technology, Guangzhou 510006, China
Published: December 2020

The electrical and the optical characteristics of dual-wavelength light-emitting diode (LED) with the newly designed selective p-doped barriers are investigated numerically. The simulation results show that the selective p-doped barriers can improve the distribution equilibria of electron and hole concentrations in each quantum well (QW). The radiative recombination rate of QW is enhanced remarkably when specific number of p-doped barriers is adopted, and the electron leakage current is suppressed obviously with this new design. Therefore, the internal quantum efficiency is improved and the trend of efficiency drooping with the increase of current injection is also alleviated. Moreover, the curve peaks of the spectrum become quite uniform when the specific number of vertically-stacked QWs is adopted, and the spectral regulation of the dual-wavelength LED is more effective.
Study on a model of topology evolution of wireless sensor networks among cluster heads and its immunization
Authors: Wang Ya-Qi  , Yang Xiao-Yuan  ,   Network and Information Security Key Lab of Armed Police Force, Electronics Technology Dept., Engineering College of Armed Police Force, Xi'an 710086, China
Published: December 2020

A new evolving network model based on complex network theory among the cluster heads is proposed to study the influence of node failure on the performance of wireless sensor network. According to the proposed model, we discuss the virus immunization strategies, and present a new immune mechanism. Theoretical analysis shows that such an evolving network not only has strong fault tolerance, but also can effectively avoid node premature death caused by the rapid energy depletion. It is also found that if the global network information is unknown, the proposed immunization strategies in this paper can obtain better immune effect than the random immunization and acquaintance immunization strategies. The theoretical analysis is verified by numerical simulations.
Adiabatic conversion from ultracold atoms to heteronuclear tetrameric molecule A3B
Authors: Li Guan-Qiang  , Peng Ping  , Cao Zhen-Zhou  , Xue Ju-Kui  ,   College of Science, Shaanxi University of Science and Technology, Xi'an 710021, China;,   College of Electronics and Information Engineering, South-Central University for Nationalities, Wuhan 430074, China;,   College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070, China
Published: December 2020

We present a theoretical scheme for conversion from ultracold atoms to heteronuclear tetrameric molecule A3B via Efimov resonace-assisted stimulated Raman adiabatic passage (ER-STIRAP). The dark state solutions of the system are obtianed for two different pathways. For the first pathway, the intermediate state is populated by homonuclear Efimov trimer A3, and the second one by heteronuclear Efimov trimer A2B. The feasibility and the effectiveness of the scheme are also verified. Meanwhile, we investigate the effects of external field parameters, including the intensity of associated laser pulses, its width, magnetic coupling strength and its detuning, on the fomation of heteronuclear tetrameric molecules. By comparison, it is found that the ultimate yield of the tetrameric molecules for the second pathway is less than ones for the first pathway. In addition, the effects of the intrinsic nolinearity of the system and the spontaneous decay in the intermediate state on the tetramer formation are discussed.
Impulsive synchronization of fractional order hyperchaotic systems based on comparison system
Authors: Ma Tie-Dong  , Jiang Wei-Bo  , Fu Jie  ,   College of Automation, Chongqing University, Chongqing 400044, China;,   Key Lab of Optoelectronic Technology and System, Ministry of Education, College of Optoelectronic Engineering, Chongqing University, Chongqing 400044, China
Published: December 2020

In this paper, a novel impulsive control method based on comparison system is proposed to realize complete synchronization of a class of fractional order chaotic systems. By constructing the suitable response system, the original fractional order error system can be converted into the integral order one. Based on the theory of Lyapunov stability and impulsive differential equations, some effective sufficient conditions are derived to guarantee the asymptotical stability of synchronization error system. In particular, some simpler and more convenient conditions are derived by taking the same impulsive distances and control gains. Compared with the existing results, the main results in this paper are more practical and rigorous. Simulation results for fractional order Chen system show the effectiveness and the feasibility of the proposed impulsive control method.
Chaotic behavior in the dynamical evolution of network traffic flow and its control
Authors: Liu Shi-Xu  , Guan Hong-Zhi  , Yan Hai  ,   Beijing Key Laboratory of Transportation Engineering, Beijing University of Technology, Beijing 100124, China
Published: December 2020

This paper presents the day-to-day dynamic evolution of network traffic flow in a simple two-route network. Firstly, a day-to-day dynamical assignment model is formulated, which can depict the evolution of network traffic flow. We have proved that the fixed point of the dynamical system, which is the stochastic user equilibrium solution, exists and is unique. Secondly, based on nonlinear dynamics theory, an equilibrium stability condition for the network is derived. Moreover, the evolution of network traffic flow is investigated through numerical experiments. Meanwhile, periodic and chaotic flows are discovered under certain conditions. Finally, a chaotic control method is derived considering OD demand as control variable.
Finite element analysis and experimental studies on fracture splitting processing by Nd: YAG laser ablation
Authors: Yu Ge  , Yang Shen-Hua  , Wang Meng  , Kou Shu-Qing  , Lin Bao-Jun  , Lu Wan-Chun  ,   Roll Forging Research Institute, Jilin University, Changchun 130025, China;,   Changchun Railway Vehicles Co. LTD, Changchun 130062, China
Published: December 2020

Laser fracture splitting technology significantly improves the processing quality and efficiency of engine crankcase main bearing block. In order to research the splitting mechanism of ductile iron material fracture notch cauterized by Nd: YAG Laser, the FEAmodel of fracture splitting processing of engine crankcase main bearing block has been developed successfully. The splitting parameters of ductile iron material (QT500-7) main bearing block is analyzed. The numerical simulation results indicate that: among all the key parameters affecting the quality of fracture splitting, the effect of notch depth on fracture splitting load is more obvious than that of the notch opening angle and radius. The value of splitting load decreases rapidly with the increasing notch depth, while the splitting load increases with the increasing notch angle and radius. The optimum value of the notch depth, angle, and radius should be respectively at 0.5 mm, 60 o, and 0.2 mm. The results have been proved by experiments. The optimum parameters obtained from the ABAQUS simulation and experiments provide a numerical reference for significantly reducing the splitting load and optimizing the fracture splitting process, help to achieve the rapid development of engine block process and promote the green manufacture of automobile industry.
Accurate calculation of elastic scattering properties of potassium and cesium atoms at ultracold temperatures
Authors: Zhang Ji-Cai  , Zhu Zun-Lue  , Sun Jin-Feng  ,   College of Physics and Information Engineering, Henan Normal University, Xinxiang 453007, China;,   Department of Physics, Luoyang Normal College, Luoyang 471022, China
Published: December 2020

In this paper, we calculate the scattering parameters for collision between potassium and cesium atoms at ultracold temperatures, such as s-wave scattering length, effective range and p-wave scattering length, by the quantum method and semiclassical method, respectively. The singlet and the triplet elastic scattering cross sections between 39K and Cs atoms at ultracold temperatures are dominated by s-wave scattering, and shape resonance occurs with the increase of collision energy. There exist pronounced g-wave and d-wave shape resonances for the singlet and the triplet cross sections, respectively. In addition, s-wave scattering lengths are calculated by using the degenerate internet state approximation for selected hyperfine states of 41KCs.
Radio-over-fiber downlink system based on a new polarization-stable millimeter-wave genarator
Authors: Liu Guan-Hui  , Pei Li  , Ning Ti-Gang  , Gao Song  , Li Jing  , Zhang Yi-Jun  ,   Institute of Lightwave Technology, Key Laboratory of All Optical Network and Advanced Telecommunication Network, Ministry of Education, Beijing Jiaotong University, Beijing 100044, China
Published: December 2020

A radio-over-fiber(ROF) downlink system based on a new polarization-stable millimeter-wave generator is proposed to reduce costs, increase transmission distance and improve system performance. Compared with traditional system, the system uses two polarization-stable laser signals produced by selecting the frequency of the polarization maintaining fiber Bragg grating(PMFBG) to generate millimeter-wave by beating frequency. It is easy to be implemented and the influence of power noise on the system is reduced. The effects of laser power, linewidth and reflectance spectrum of PMFBG on the performance of millimeter-wave are analyzed; Simulation shows that the frequency of millimeter-wave is affected by the group delay, the length, the dispersion of the polarization-maintaining fiber(PMF) and the width, the chirp coefficient of laser's pulse profile. After optimizing parameters of PMF, millimeter-wave of 60GHz is generated, and the ROF downlink system is analyzed. The results of the study show that the eye diagrams demodulated in the mobile station are excellent when the optical carrier which is modulated by the millimeter-wave serving as sub-carrier transmits over 80 kilometers from center station to base station. The excellent performance of the system is verified.
Infrared thermal wave imaging for inspecting the insulation layer of superconducting busbar in thermonuclear experimental reactor
Authors: Chen Da-Peng  , Zeng Zhi  , Zhang Cun-Lin  , Jin Xue-Yuan  , Zhang Zheng  ,   School of Material Science and Engineering, Beihang University, Beijing 100191, China;,   Institute of Physics and Electronic Engineering, Chongqing Normal University, Chongqing 400047, China;,   Beijing Key Laboratory for Terahertz Spectroscopy and Imaging, Key Laboratory of Terahertz Optoelectronics, Ministry of Education, Department of Physics, Capital Normal University, Beijing 100048, China
Published: December 2020

This work aims at developing a thermal wave imaging method for testing the insulation layer of superconducting busbar in thermonuclear experimental reactor. In the paper, a film bag filled with hot water is used to heat the sample surface. The approximate theoretical model of transient heat conduction under an instantaneous cylindrical surface source in cylindrical structure is given. Through simulation and analysis of the theoretical model, it is found that differential processing of the thermal cooling signals can improve the signal contrast between defects and non-defects areas. Compared with the flash pulse excitation method, the contact excitation method can detect deep defects.
Simple harmonic oscillator immune optimization algorithm for solving vertical handoff decision problem in heterogeneous wireless network
Authors: Zhu Si-Feng  , Liu Fang  , Chai Zheng-Yi  , Qin Yu-Tao  , Wu Jian-She  ,   Department of Mathematics & Information Science, Zhoukou Normal University, Zhoukou 466001, China;,   School of Computer Science & Technology, Xidian University, Xi'an 710071, China
Published: December 2020

In heterogeneous wireless network environment, wireless local area network (WLAN) are usually deployed within the coverage of a cellular network to provide users with the convenience of seamless roaming among heterogeneous wireless access networks. Vertical handoffs between the WLAN and the cellular network could occur frequently, with regard to vertical handoff performance, there is a critical need for developing algorithms for connection management and optimal resource allocation for seamless mobility. In this paper, we develop a mathematical model for vertical handoff decision problem, propose an artificial simple harmonic oscillator immune algorithm-based vertical handoff decision scheme, and perform the simulation experiments to validate proposed solution. Experimental result shows that the proposed solution, compared with literature solutions, can not only balance the overall load among all networks but also increase the collective battery lifetime of mobile terminals, and has the advantage of good application value.
Analytical dispersion relation model for conduction band of uniaxial strained Si
Authors: Wang Guan-Yu  , Song Jian-Jun  , Zhang He-Ming  , Hu Hui-Yong  , Ma Jian-Li  , Wang Xiao-Yan  ,   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, based on the framework of kp method, the influence of uniaxial stress on the conduction band energy-band structure of bulk-Si is analysed first, the coupling of 1 and 2 bands at the X point, and the influence of that band-band coupling on the minimum of energy valley are then separately discussed under the action of shear strain. On that basis, the dispersion relation close to the minimum is obtained. Furthermore, the different valley orientations need to be taken into account. Using the coordinate transformation, the modelling for dispersion relation of each valley with arbitrary uniaxial stress is finally achieved. The proposed analytical model in this paper is also suited to the understanding of the physical properties of uniaxial strained Si material and may provide some references for the study on bandstructure and electrical properties of the inversion layer in uniaxial strained Si nMOSFETs.
Researching progress of the 1/f noise in TMR and GMR sensors
Authors: Wu Shao-Bing  , Chen Shi  , Li Hai  , Yang Xiao-Fei  ,   Huazhong University of Science & Tech, Dept. of Electronic Science & Tech, Wuhan 430074, China
Published: December 2020

The low-frequency noise is the most important influence on the low frequency resolution and sensitivity in tunnel junction magnetoresistance(TMR) sensors and giant magnetoresistance (GMR) sensor for the large noise power density. In this paper, We describe the 1/f noise characteristics, sources, theoretical models, testing methods and noise reduction measures for TMR sensors and GMR sensors, and the detailed physical model of 1/f noise in the tunnel junction magnetoresistive sensor is explained. By nano-simulation software Virtual NanoLab, Fe/MgO/Fe magnetic tunnel junctions (MTJs) with different thicknesses of MgO layer are studied. Their tunneling probabilities and TMR change rates are simulated and calculated, the conservative and the optimistic estimates of the Change rate of TMR are 98.1 % and 10324.55%.While the influence of MgO thickness on noise is studied through the MTJ model. To study the noise dependance on external magnetic field, an magnetic shielding equipment for noise measurement is set up, and the tests show that the noise in the magnetic shielding environment is significantly reduced.
Imaging of human thyroid in vitro using focused photoacoustic tomography
Authors: Zeng Zhi-Ping  , Xie Wen-Ming  , Zhang Jian-Ying  , Li Li  , Chen Shu-Qiang  , Li Zhi-Fang  , Li Hui  ,   Key Laboratory of OptoElectronic Science and Technology for Medicine, Ministry of Education, Fujian Provincial Key Laboratory of Photonic Technology, School of Physics and OptoElectronics Technology, Fujian Normal University, Fuzhou 350007, China;,   The First Affiliated Hospital of Fujian Medical University, Fuzhou 350007, China
Published: December 2020

Locating and imaging the specific pathological lesions in human thyroid are pretty helpful for reliable diagnosis and effective treatment of thyroid nodules. In this paper, we evaluate the feasibility of photoacoustic tomography (PAT) for imaging thyroid tissue in vitro. Imaging is performed based on an imaging system with a 30 MHz focused transducer. In the experiment, 350 upm transverse resolution and 74 upm axial resolution are achieved. A normal thyroid tissue and the tissue with a mimic lesion embedded are imaged in vitro, Separately. As a result, the localization and the imaging of mimic pathological lesion in human thyroid tissue are realized. We demonstrate that our imaging system is able to detect the lesion from normal thyroid tissue successfully. This technique is expected to be a potential clinical tool for increasing diagnostic accuracy and performing more effective treatment of thyroid diseases.
Synthesis and infrared up-conversion photostimulated luminescence properties of a novel optical storage material Sr2SnO4: Tb3 +, Li+
Authors: Qin Qing-Song  , Ma Xin-Long  , Shao Yu  , Yang Xing-Yu  , Sheng Hong-Fei  , Yang Jing-Zhong  , Yin Yao  , Zhang Jia-Chi  ,   Ministry of Education Key Laboratory of Magnetism and Magnetic Materials Lanzhou University, Lanzhou 730000, China
Published: December 2020

The novel electron trapping material of Sr2SnO4: Tb3+, Li+ for optical storage is synthesized by the solid state method. Stimulated by 980 nm infrared laser, the material shows intense up-conversion photostimulated luminescence. The ultraviolet light at 292 nm is an optimal writing source. The material has less shallow traps, which corresponds to its weak afterglow (less than 500 s). On the other hand, this material has lots of deep traps. Thus, the Sr2SnO4:Tb3 +, Li+ is a promising optical storage material. In addition, we propose the optical storage luminescence mechanism of Sr2SnO4:Tb3 +, Li +.
Properties of localized surface plasmon resonance of gold nanoshell pairs
Authors: Zou Wei-Bo  , Zhou Jun  , Jin Li  , Zhang Hao-Peng  ,   Institute of Optics and Optoelectronics, Ningbo University, Ningbo 315211, China
Published: December 2020

The characteristics of scatting and extinction spectra of gold nanoshell pairs, dependent on the its geometry and physical parameters, are investigated by the Finite Element Method based on the plasmon hybridization theory. The numerical results indicate that the resonante peaks in the scattering spectra and the extinction spectra emerge from blue-shift to red-shift with the increases of the thickness of gold nanoshells, whereas they present the red-shift with the decrease of the interparticle separation or with the increases of the size and the refractive index of inner core of gold nanoshells. In the same time, for the case of decreasing the inner core size and the shell thickness or increasing the refractive index of inner core, the intensity of the scattering resonance and the extinction resonance decrease. And, with the decrease of the interparticle separation, the intensity of the scattering resonance of gold nanoshell pairs trends to first increase and then decrease, while the intensity of the extinction resonance increases gradually. All the above is in agreement with the analysis of the plasmon hybridization theory.
Cellular automaton model with MeshTV interface reconstruction technique for alloy dendrite growth
Authors: Wei Lei  , Lin Xin  , Wang Meng  , Huang Wei-Dong  ,   State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi'an 710072, China
Published: December 2020

In this paper, cellular automata (CA) model for free dendritic growth of alloy is presented, in which the interface cell is refined by MeshTV interface reconstruction algorithm. In the present CA model, the growth kinetic for both pure material and alloy is used. The effect of interfacial energy anisotropy parameter is validated in the CA model. The dendrite tip growth velocity and tip radius are compared with those of the LGK theoretical model, when =0.02.
Space charge in surface fluorinated polyethylene
Authors: An Zhen-Lian  , Liu Chen-Xia  , Chen Xuan  , Zheng Fei-Hu  , Zhang Ye-Wen  ,   Ministry of Education Key Laboratory of Advanced Microstructure Materials, Department of Physics, Tongji University, Shanghai 200092, China;,   State Key Laboratory of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, Xi'an 710049, China
Published: December 2020

Direct fluorination, as one of the most effective approaches to chemical modification of polymer surfaces, has been widely developed from fundamental researches to industrial applications for about forty years in chemical industry field. However, today, its investigations and applications in adjusting and controlling the electrical properties of polymers are still deficient. The present paper attempts to briefly bring together our study results obtained in recent years and recently, related to the influence of surface fluorination on space charge behavior in polyethylene (PE), and to give a concluding discussion on the correlation between space charge accumulation in PE and its fluorinated layer properties and characteristics. The results show that a very thin fluorinated layer can yield effective charge suppression in the absence of oxygen in the reactive gas mixtures, whereas a very thick fluorinated layer with a high degree of fluorination is needed to achieve the effective charge blocking in the presence of oxygen. Among the electrical factors influencing space charge, charge transport properties of the fluorinated layer are more important than its charge trapping properties and permittivity or polarity to prevent charge injection into the bulk material, although high permittivity and deeply trapped charges in the surface layer would reduce the interface electric field and thus decrease charge injection from the electrodes. The charge transport properties of the fluorinated layer are closely related to its free volume, and oxygen in the reactive gas mixtures has a strong negative influence on the decrease of free volume and thus on the suppression of space charge.
Research on the focusing mechanism of one dimensional time reversal EM wave in sub-wavelength metal wire array
Authors: Zhang Zhi-Min  , Wang Bing-Zhong  , Ge Guang-Ding  , Liang Mu-Sheng  , Ding Shuai  ,   Institute of Applied Physics, University of Electronic Science and Technology of China, Chengdu 610054, China;,   School of Physics and Electronic Information, Huaibei Normal University, Huaibei 235000, China
Published: December 2020

Based on the equivalent dielectric model of the periodic metal wire array, the analytical expression of time reversal EM wave in the metal wire array is derived using transmission line method. Then, the influence of metal wire radius, metal wire array period and the amount of layers on time reversal EM wave focusing property is discussed within the equivalent dielectric model. This structure can be used to focus time reversal EM wave in the far field, at the same time, it provides an engineering reference for time reversal technique.
Experimental realization of wireless transmission based on terahertz quantumcascade laser
Authors: Tan Zhi-Yong  , Chen Zhen  , Han Ying-Jun  , Zhang Rong  , Li Hua  , Guo Xu-Guang  , Cao Jun-Cheng  ,   Key Laboratory of Terahertz Solid-State Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China
Published: December 2020

A terahertz wireless transmission system is constructed by using a continuous wave terahertz quantum-cascade laser (THz QCL) and a spectrally-matched terahertz quantum-well photodetector (THz QWP). The transmission bandwidth of the system is measured. The transmission processes at 4.13 THz of a picture file are demonstrated by employing the above system, and the both message totally consistent with the original one are received correctly. Hence, the feasibility of wireless transmission based on THz QCL and THz QWP devices is confirmed. Finally, we analyze the transmission rate of the demonstrating system and give the improving methods.
Complexity analysis of chaotic pseudo-random sequences based on spectral entropy algorithm
Authors: Sun Ke-Hui  , He Shao-Bo  , He Yi  , Yin Lin-Zi  ,   School of Physics and Electronics, Central South University, Changsha 410083, China;,   School of Physics Science and Technology, Xinjiang University, Urumqi 830046, China
Published: December 2020

To analyze the complexity of chaotic pseudo-random sequences accurately, spectral entropy (SE) algorithm is used to analyze chaotic pseudo-random sequences generated by Logistic map, Gaussian map or TD-ERCS system. The SE algorithm has few parameters, and has high robustness with the sequence length N (the only parameter) and the pseudo-random binary number K. Using sliding window method, the evolution features are analyzed, and complexity of discrete chaotic systems with different initial conditions and system parameters are calculated. The results show that SE algorithm is effective for analyzing the complexity of the chaotic pseudo-random sequences, and TD-ERCS is a high complexity system with wide parameter range, and has the best complex performance among the three chaotic systems. The complexity of the same chaotic system with different initial values fluctuates within a small range. It provides a theoretical and experimental basis for the applications of chaotic sequences in the field of information security.
Numerical study on the dynamic behavior of internal structure of 1+1-dimensional ballistic deposition model
Authors: Xun Zhi-Peng  , Tang Gang  , Xia Hui  , Hao Da-Peng  ,   Department of Physics, China University of Mining and Technology, Xuzhou 221116, China
Published: December 2020

In this paper, the dynamic behavior of internal structure of 1+1-dimensional ballistic deposition model is simulated by means of Kinetic Monte Carlo. The dynamic behaviors of the porosity and internal interface are investigated. It is found that the porosity, with the standard Gaussian distribution, increases very fast at the initial times and reaches a saturation valve, which is independent of the linear substrates. In addition to the surface width, the new method of extreme statistics is also employed to analyze the dynamic behavior of internal interface. The results show that the evolution of the internal interface of 1+1-dimensional ballistic deposition model satisfies the standard Family-Vicsek scaling, and belongs to the universality class described by the Kardar-Parisi-Zhang equation. Finally, the finite-size effects obtained by the two theoretical methods, i.e., surface width and extreme statistics are compared.
A cellular automata model of pedestrian evacuation in rooms with squared rhombus cells
Authors: Yong Gui  , Huang Hai-Jun  , Xu Yan  ,   School of Economics and Management, Beihang University, Beijing 100191, China;,   School of Statistics and Mathematics, Inner Mongolia University of Finance and Economics, Huhhot 010051, China
Published: December 2020

The modified floor field cellular automata model is used to simulate the pedestrian evacuation in rooms which are discretized into squared rhombus cells. This discretization can effectively stop pedestrians to move against walls or obstacles. The pedestrian transition probabilities from one cell to neighbor cells are computed by considering various factors influencing evacuation. Simulation results show that the pedestrian distribution nearby exit is basically the same as that indicated by the experimental snapshot, the evacuation time increases almost linearly with exit width, and the flow rate from exit is close to the one observed from experiment.
Self-consistent thermodynamical treatment to strange quark matter with density-dependent bag constant and properties of hybrid stars
Authors: Bao Tmurbagan  , Yang Xing-Qiang  , Yu Zi  ,   College of Physics and Electronic Information, Inner Monggolia University for Nationalaties, Tongliao 028043, China;,   Department of Physics, Nanyang Normal University, Nanyang 473061, China;,   College of Science, Nanjing Forestry University, Nanjing 230037, China
Published: December 2020

Thermodynamics of strange quark matter with density-dependent bag parameter is given by making use of MIT bag model, and properties of strange and hybrid stars are investicated by using them. Our results indicate that an extra term should be appended to the pressure expression of strange quark matter but not to the energy density when the bag constant is density-dependent, which assures self-consistency of the system. With this extra term, strange quark matter equations of state soften, gravitational mass and corresponding radius of strange star decrease compared with the inconsistent case. The hybrid star equations of state soften and corresponding mass and radius for hybrid star decrease when this model is used to describe quark phase in hybrid star. These indicate that new thermodynamics for strange quark matter with density-dependent bag parameter has an important influence on properties of strnge star and hybrid star.
Theoretical study on He-N2 interaction potential
Authors: Linghu Rong-Feng  , Xu Mei  , Lü Bing  , Song Xiao-Shu  , Yang Xiang-Dong  ,   School of Physics and Electronic Science, Guizhou Normal College, Guiyang 550018, China;,   School of Physics and Electronic Science, Guizhou Normal University, Guiyang 550001, China;,   Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, China
Published: December 2020

In this paper, the ab initio quantum mechanics method is used for further investigating the He-N2 interactional potential energy function. By means of different methods and basis sets, the energy data in space are calculated. Finally the accurate He-N2 interactional potential energy function is obtained by using QCISD(T)/6-311++G(3df, 2pd) with Boy and Bernardi's Full Couterpoise to eliminate the basis set superposition error. The calculated differential cross sections of He-N2 collision are in good agreement with the experimental data. The rules of differential cross sections of He-N2 collision at different collision energies are derived.