bluuebunny/crossref_metadata_2025 huggingface dataset:
STM study of growth of manganese silicide thin films on a Si(100)-21 surface
Authors: Li Wei-Cong  , Zou Zhi-Qiang  , Wang Dan  , Shi Gao-Ming  ,   Instrumental Analysis Center, Shanghai Jiaotong University, Shanghai 200240, China;,   Department of Physics, Shanghai Jiaotong University, Shanghai 200240, China
Published: December 2020

Manganese silicides are promising candidates for microelectronics and spintronics materials. A good understanding of their growth mechanisms is a crucial step toward their practical applications. In this paper, a Mn film of ～4 monolayer is deposited on a Si(100)-21 surface by molecular beam epitaxy. The solid reaction between the Mn film and the silicon substrate in a temperature range of 250750℃ is studied using scanning tunneling microscopy. At room temperature, the as-deposited Mn atoms do not react with the silicon atoms and the film consists of disordered Mn clusters. When the sample is annealed at a higher temperature than 290℃, the Mn begins to react with the Si and forms small three-dimensional (3D) islands of Mn-rich silicides and silicide islands of dendritic shapes. When the annealing temperature reaches 325℃, small tabular islands, which correspond to MnSi, start to grow on the Si substrate. At an annealing temperature of 525℃, silicide islands with dendritic shapes all disappear; meantime several large tabular islands, which correspond to MnSi1.7, are formed. When the annealing temperature is higher than 600℃, 3D islands and small tabular islands all disappear while large tabular islands remain there. These results demonstrate that the morphology and the structure of the film strongly depend on annealing temperature. The average size (area) of the remaining islands increases with the increase of annealing time. Time dependence of the averaged island area indicates that the growth of the islands follows the diffusion limited Ostwald ripening mechanism.
Kinetics of two-species aggregation-annihilation processes on globally coupled networks
Authors: Zhu Biao  , Li Ping-Ping  , Ke Jian-Hong  , Lin Zhen-Quan  ,   College of Physics and Electronic Information Engineering, Wenzhou University, Wenzhou 325035, China
Published: December 2020

Kinetics of diffusion-limited aggregation-annihilation process on globally coupled networks is investigated by the Monte Carlo simulation. In the system, when two clusters of the same species meet at the same node, they will aggregate and form a larger one; while if two clusters of different species meet at the same node, they will annihilate each other. The simulation results show that, (i) if the two species have equal initial concentrations, the concentration of clusters c(t) and the concentration of particles g(t) follow power laws at large time, c(t)～t- and g(t)～t-, with the exponents and satisfying =2 and =2/(2 + q); meanwhile, the cluster size distribution can take the scaling form ak(t)=k-t-(k/tz), where -1.27q, (3 + 1.27q)/(2 + q) and z=/2=1/(2 + q); (ii) if the two species have different initial concentrations, the cluster concentration of the heavy species cA(t) follows the power law at large time, cA (t)～t-, where =1/(1 + q), and the cluster size distribution of the heavy species can obey the scaling law at large time, ak(t)=k-t-\varPhi (k/tz), with the scaling exponents -1.27q, (2 + 1.27q)/(1 + q) and z==1/(1 + q). The simulation results accord well with the reported theoretic analyses.
The effects of substrate temperature and oxygen pressure on the crystal strcture and transport properties of Bi2Sr2Co2Oy thermoelectric films deposited by pulsed laser deposition
Authors: Wang Shu-Fang  , Chen Shan-Shan  , Chen Jing-Chun  , Yan Guo-Ying  , Qiao Xiao-Qi  , Liu Fu-Qiang  , Wang Jiang-Long  , Ding Xue-Cheng  , Fu Guang-Sheng  ,   Hebei Key Laboratory of Optic-Electronic Information and Materials, Hebei University, Baoding 071002 China
Published: December 2020

We fabricate Bi2Sr2Co2Oy films on c-Al2O3 by pulsed laser deposition and investigate the effects of substrate temperature and oxygen pressure on the crystal stucture and the transport properties of the films. The resulting single phase c-axis Bi2Sr2Co2Oy films obtained under the optimal condition have a room temperature resistivity of about 2.9 m/cm and a seebeck coefficient of 110 V/K, leading to a larger power factor than that of the single crystal. In addition, a negative magnetroresistance of 40% at 2K and 9T is observed in the films.
Trap levels in low density polyethylene doped with nanoparticles by photo-stimulated discharge
Authors: Zhu Zhi-En  , Zhang Ye-Wen  , An Zhen-Lian  , Zheng Fei-Hu  ,   MOE Key Laboratory of Advanced Micro-structure Material, Department of Physics, Tongji University, Shanghai 200092, China
Published: December 2020

Trap levels in nanoparticle doped low density polyethylene (LDPE) are investigated by photo-stimulated discharge (PSD). The PSD spectra in MgO/LDPE and Al2O3/LDPE nanocomposites with the different mass percentages and different nanocomposites with the same mass percentage are obtained by continuous scanning mode, which can be qualitatively estimate the trap energy distribution. The trap levels in Al2O3/LDPE nanocomposite are quantitatively described by step scanning mode. The experimental results indicate that the trap levels in Al2O3/LDPE nanocomposites with the Al2O3 content of more than 0.2% and MgO/LDPE nanocomposites with the MgO content of more than 0.5% are deeper than those of the virgin LDPE. According to the relevant reports on the effect of nanoparticle doping on space charge injection, it is considered that the suppression of space charge is probably correlated with the deeper trap levels in nanocomposites.
Through-silicon-via-aware interconnect prediction model for 3D integrated circuirt
Authors: Qian Li-Bo  , Zhu Zhang-Ming  , Yang Yin-Tang  ,   School of Microelectronics, Xidian University, Xi’an 710071, China
Published: December 2020

Through-silicon-via (TSV) is one of the major design techniques in three- dimensional integrated circuit (3D IC). Based on the parasitic parameter extraction model, the parasitic resistance-capacitance (RC) parameters for different size TSVs are acquired and validated with Q3D simulation data. Using the results of this model, closed-form delay and power consumption expressions for buffered interconnect used in 3D IC are presented. Comparative results with 3D net without TSV in various cases show that TSV RC effect has a huge influence on delay and power of 3D IC, which leads maximum delay and power comsumption to extra increase 10% and 21\% on average, respectively. It is crucial to correctly establish a TSV-aware 3D interconnect model in 3D IC front-end design.
A dielectric-metal-loaded thick-screen frequency selective surface having circle aperture elements
Authors: Tang Guang-Ming  , Miao Jun-Gang  , Dong Jin-Ming  ,   School of Electronic and Information Engineering, Beihang University, Beijing 100191, China
Published: December 2020

Thick screen frequency selective surface (FSS) is a very effective means of realizing the stealth radome, since it can better improve the bandwidth performance of FSS. In order to fully grasp the transmission characteristics of thick screen FSS and to provide a sound foundation of realizing their applications for bandpass radomes, a dielectric-metal-loaded thick-screen FSS is designed in this paper. The transmission properties of this structure are analyzed by using the moment method. The transmission characteristics of this structure are investigated when some parameters including the diameter of filling dielectric, the diameter of filling metal, the thickness of filling dielectric, incidence angle of electromagnetic wave, and unit spacing are changed. Simulation results show that the diameter of filling dielectric, the diameter of filling metal, the thickness of loading dielectric, thickness of filling metal, incidence angle of electromagnetic wave, and unit spacing can influence the transmission properties of the dielectric-metal-loaded thick-screen FSS. The diameter of filling metal and the thickness of loading dielectric can be adjusted appropriately in order to obtain a wide passband width and a better penetrating percentage of the central frequency. The novel structure provides a valuable reference for the application in stealth curved streamlined radomes.
The study of EGFR transport in single cell using an automatic method of trajectory identification
Authors: Li Hui  , Duan Zhao-Wen  , Dou Shuo-Xing  , Wang Peng-Ye  ,   Key Laboratory of Soft Matter Physics, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
Published: December 2020

We study the characteristics of motion modes of epidermal growth factor receptor (EGFR) trafficking in single cell, by using the automatic method of trajectory identification which is based on the directional persistence and mean square displacement analysis. Each trajectory of EGFRs is divided into four modes of motion: directional motion, super-diffusion, Brownian motion and sub-diffusion. The corresponding dynamic parameters of different modes of motion are calculated and discussed, providing an insight into intracellular trafficking of receptors.
The application of phase contrast imaging to ICF multi-shell capsule diagnosis
Authors: Yan Ji  , Jiang Shao-En  , Su Ming  , Wu Shun-Chao  , Lin Zhi-Wei  ,   Research Center of Laser Fusion, Mianyang 621900, China
Published: December 2020

With the development of the research on inertial confinement fusion (ICF), there is needed a diagnostic technique for low Z materials.The phase contrast imaging, which relies on gradients in the refractive index and wave interference, is proposed to characterize the typical ICF (inertial confinement fusion) capsule shell. In our work it is indicated that the phase contrast imaging obtained with a micro-focus X-ray source provides complementary information about the capsule shell with high resolution 2 upm, and has advantages of absorb imaging. Such a capsule shell diagnostic technique is very useful for ICF diagnoses. Besides, we propose an approach to obtaining of the optimum contrast and spatial resolution in phase contrast imaging. It is a guidance in obtaining an excellent result in phase contrast imaging experiment, and can be widely used in biomedicine, materials science.
Generalized variational principles for three kinds of atmospheric waves
Authors: Song Jun-Qiang  , Cao Xiao-Qun  , Zhu Xiao-Qian  , Zhang Wei-Min  , Zhao Jun  ,   School of Computer Science, National University of Defense Technology, Changsha 410073, China
Published: December 2020

The semi-inverse method is proposed by He to establish generalized variational principles for mathematical and physical problems, in which the variational crisis brought by the Lagrange multiplier method can be eliminated. with He's semi-inverse method, a family of variational principles is constructed for Rossby wave, atmospheric acoustic wave and gravity wave respectively. The obtained variational principles have also proved correct.
Improved particle filter in data assimilation
Authors: Leng Hong-Ze  , Song Jun-Qiang  , Cao Xiao-Qun  , Yang Jin-Hui  ,   College of Computer, National University of Defense Technology, Changsha 410073, China
Published: December 2020

Owing to the fact that standard particle filter and ensemble Kalman filter can not efficiently represent the posterior probability density function (PDF), an improved particle filter is proposed. In this algorithm, an innovation step is introduced after the prediction step, and the analyses of non-observation time and observation time are treated separately. The numerical simulations of a low- and a high-dimensional systems show that this new particle filter can follow the true state of a highly nonlinear non-Gaussian system very well.
Multiple spatial coherence resonances induced by white gaussian noise in excitable network composed of Morris-Lecar model with class Ⅱ excitability
Authors: Li Yu-Ye  , Jia Bing  , Gu Hua-Guang  ,   College of Life Sciences, Shaanxi Normal University, Xi’an 710062, China
Published: December 2020

To study the effect of noise on the network and the influence of noise on the spatio-temporal behaviors of the network, a homogeneous network of excitable cells is constructed, in which the classical Morris-Lecar neuron model behaves as a unit by electric coupling to neighbouring ones. The deterministic behavior of each unit is a resting state corresponding to class Ⅱ excitability. Under the action of white Gaussian noise in the network, spiral wave can be induced within a large range of noise intensity, while disordered spatiotemporal structure is induced within a certain small intensity range. With the increase of noise intensity, spiral wave is characterized by a transition back and forth between simple structure and complex structure, or appears alternately with the disordered structure. By calculating spatial structure function and signal-to-noise ratio (SNR), it is found that the SNR of spiral wave with a simple structure is higher and the SNR becomes lower when the spiral wave has a complex or an even disordered structure. The SNR curve shows that multiple peaks appear with the increase of noise intensity, which indicates that white Gaussian noise can induce the multiple spatial coherence resonance in an excitable cellular network, and suggests that there are many opportunities to select diverse intensity noises to be rationally used in a realistic excitable system.
Research on the mode competition in a w-band lossy ceramic-loaded gyrotron backward-wave oscillator
Authors: Du Chao-Hai  , Li Zheng-Di  , Xue Zhi-Hao  , Liu Pu-Kun  , Xue Qian-Zhong  , Zhang Shi-Chang  , Xu Shou-Xi  , Geng Zhi-Hui  , Gu Wei  , Su Yi-Nong  , Liu Gao-Feng  ,   Key Laboratory of High Power Microwave Sources and Technologies, Institute of Electronics, Chinese Academy of Sciences, Beijing 100190, China;,   Graduate University of Chinese Academy of Sciences, Beijing, 100190 China
Published: December 2020

Mode competition induces non-stationary oscillations during the operation of a gyrotron backward-wave oscillator (gyro-BWO), which severely reduces its tunable bandwidth and output power. Self-consistent nonlinear theory is used to study the modes-competition mechanism of a W-band fundamental TE01 mode gyro-BWO. Tapered non-resonant interaction circuit structure and loading lossy ceramic are employed to suppress the competing modes, as a way of preventing non-stationary oscillation in the circuit. Systematically optimized interaction circuit is capable of suppressing all the competing modes and can stably operate in the fundamental axial mode of the TE01 mode. Calculation indicates that a peak power of 105 kW and a -3 dB tunable bandwidth of 5.4% are attainable. This is meaningful and provides a theoretical foundation for developing broadband millimeter gyro-BWOs in the applications of counter-measure system, non-destructive detection, plasma diagnosis, material processing, and so on.
The degradation mechanisms of lamp used BaMgAl10O17: Eu2+,Mn2+ phosphor
Authors: Zhou Mei-Jiao  , Zhang Jia-Chi  , Wang Yu-Hua  ,   Ministry of Education Key Laboratory of Magnetism and Magnetic Materials Lanzhou University, Lanzhou 730000, China
Published: December 2020

The thermal and the ultraviolet radiation degradation mechanisms of lamp used BaMgAl10O17:Eu2+, Mn2+ phosphor are investigated in a comparative way. Thermal and the ultraviolet radiation treatments can both seriously damage the luminous efficiency of BaMgAl10O17:Eu2+,Mn2+. It is revealed that the thermal degradation is involved in the oxidation and migration of Eu2+ ions. The ultraviolet radiation makes the Eu2+ in metastable state, which weakens the direct absorption of Eu2+ and thus reduces the relative luminescence intensity of BaMgAl10O17:Eu2+,Mn2+.
Analysis and design of a double-anode magnetron injection gun for 1THz gyrotron
Authors: Chen Xu-Lin  , Zhao Qing  , Liu Jian-Wei  , Zheng Ling  ,   Institute of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054, China
Published: December 2020

Based on the electron optics theory, through a massive numerical calculation by programming, a double-anode magnetron injection gun (MIG) for a 1THz gyrotron is designed. The method of calculation and design of MIG is expounded, and the problem that high magnetic compression ratio in THz gyrotron(compression ratio of 125 in electron gun for 1THz gyrotron in this paper)could lead to the reversal of direction of electron flow is also detailedly analyzed and simulated. Through simulation and optimization, an MIG with a modest velocity ratio of the beam (=1.3) and a low velocity spread (8%) is designed.
Experimental research on single-frequency fiber Raman amplifier
Authors: Xu Jiang-Ming  , Leng Jin-Yong  , Han Kai  , Zhou Pu  , Hou Jing  ,   College of Optoelectronic Science and Engineering, National University of Defense Technology, Changsha 410073, China
Published: December 2020

Single-frequency fiber Raman amplifier (SF-FRA) is known for the ability of all-band amplification, and it is very attractive for the amplification of single-frequency seed light at a special wavelength, such as 1178nm and 1271nm. The 1080nm single-frequency signal light is amplified by a 1031nm pump source, and the influences of seed power of single-frequency signal light, length of Raman gain fiber, pump scheme are experimentally investigated. The results show that the efficiency of SF-FRA increases with the enhancement of the single-frequency signal power and the length of Raman gain fiber. The efficiency of co-pump SF-FRA is higher than that of the counter-pump SF-FRA. The measure ments show that the linewidth of single-frequency signal light is not broadened obviously in the process of Raman amplification. The visibilities of the rapid-exposure pattern of far-field interference of single-frequency seed light and the amplified light are 0.814 and 0.719, respectively. The results show that the coherence of single-frequency signal light is affected by the SF-FRA more or less. These experimental results can provide a reference for designing other special wavelength SF-FRA.
Universal theory of incoherently coupled spatial solitons families in photorefractive crystals
Authors: Ji Xuan-Mang  , Jiang Qi-Chang  , Liu Jin-Song  ,   Department of Physics and Electronic Engineering, Yuncheng University, Yuncheng 044000, China;,   College of Optoelectronic Science and Engineering, Huazhong University of Science and Technology, WuHan 430074, China
Published: December 2020

The incoherently coupled soliton families are predicted in photovoltaic photorefractive crystals illuminated by E-polarized incoherent uniform back-ground irradiation with a divider resistance under steady-state conditions. These soliton families can be established provided that the incident optical beams share the same polarization and wavelength, and are mutually incoherent. When these incoherent coupled soliton families propagate together, all components can propagate stably in photorefractive crystal. Moreover, such soliton families reduce into spatial soliton or incoherently coupled soliton pairs when they contain only one or two components. The 14 kinds of incoherently coupled spatial soliton families can be obtained from this theory by adjusting the value of the divider resistance, E-polarized back-ground irradiation, the biased electric field and photovoltaic electric field. Previous theories advanced individually elsewhere for these soliton families can be obtained by simplifying this theory under appropriate conditions.
The characteristics of internal waves generated by a revolution body in a stratified fluid with a pycnocline
Authors: Wang Jin  , You Yun-Xiang  , Hu Tian-Qun  , Wang Xiao-Qing  , Zhu Min-Hui  ,   State Key Laboratory of Ocean Engineering, Shanghai Jiaotong University, Shanghai 200030, China;,   State Key Laboratory of Microwave Imaging Technology, Institute of Electronics, Chinese Academy of Sciences, Beijing 100080, China
Published: December 2020

Experiments are conducted for the characteristics of both body and wake-generated internal waves due to a revolution body (aspect ratio 7:1) in a stratified fluid with a pycnocline where the revolution body is horizontally towed in forward and backward ways. Results show that the body-generated internal waves are a type of stationary multiple-mode Lee wave structures, and the wake-generated internal waves are a type of non-stationary quasi-Lee structures produced by the large-scale coherent structure in the turbulent wake acting as a moving excitation with respect to the towed revolution body. The transition between Lee and quasi-Lee waves occurs at a critical Froude number Frc which is shown to be linearly dependent on the aspect ratios of the revolution bodies where the wave patterns for FrFrc are dominated byLee waves,whereas the wave patterns forFrFrcare dominated by quasi-Lee waves,Fr is the Froude number for the characteristic diameter of the revolution body. For the quasi-Lee waves, the dimensionless peak-to-peak amplitudes linearly increase with Fr and the Froude numbers relative to the correlation velocities remain at a relatively constant value of approximately 0.8 regardless of the aspect ratios. Moreover, the head and the tail shapes of the revolution body have no remarkable influence on the critical Froude number Frc, as well as both the Froude numbers relative to the correlation velocities and the dimensionless peak-to-peak amplitudes of the quasi-Lee waves.
Effects of an external magnetic field on multipactor on a dielectric surface
Authors: Cai Li-Bing  , Wang Jian-Guo  , Zhu Xiang-Qin  , Wang Yue  , Xuan Chun  , Xia Hong-Fu  ,   Northwest Institute of Nuclear Technology, Xi’an 710024, China;,   School of Electronic and Information Engineering, Xi’an Jiaotong University, Xi’an 710049, China
Published: December 2020

The dielectric surface breakdown has become a major factor of restricting the output power of high power microwave source. And the multipactor is the key phase of the process of the dielectric surface breakdown. In this paper, the multipactors in external magnetic fields with different strengths are simulated by using the particle-in-cell method. And the effect of the external magnetic field on multipactor is also studied. The results show that when the external magnetic field reaches a certain value, the multipactor is suppressed in the half time of the microwave transmission. So the power capability can be increased to more than four times through the suppression of the multipactor by the external magnetic field under the ideal condition.
The effect of the divertor operation regimes on the plasma parallel flow in the edge of a tokamak
Authors: Ou Jing  , Yang Jin-Hong  ,   Institute of Plasma Physics, Chinese Academy of Sciences, Heifei 230031, China;,   Center for Magnetic Fusion Theory, Chinese Academy of Sciences, Heifei 230031, China
Published: December 2020

Based on the variations of the static pressure along the magnetic field line in different divertor operation regimes, the effects of the divertor operation regimes on the plasma parallel flow at the edge of a tokamak are investigated using a one-dimensional fluid model. In low recycling regime, the variation of the static pressure along the field line is obvious from the scrape-off layer (SOL) region near the X-point, and the variation tendency is the same as that of the density. The Mach number of the plasma parallel flow increases along the magnetic field line and the variation is from gentle to sharp. In high recycling regime, the static pressure does not change much except in the near divertor plate region, as a result, the Mach number of the plasma parallel flow varies gently in the SOL region and the most of the divertor region, and it increases rapidly in the near divertor plate region. The variation of the static pressure in weak divertor detachment regime is similar to that in high recycling regime, but the static pressure shows decrease tendency in the SOL region near the X-point, consequently, the Mach number of the plasma parallel flow at X-point is larger than that in high recycling regime. In strong divertor detachment regime, static pressure decreases obviously in the SOL region and away from the divertor plate region, where the static pressure decreases rapidly, and a high Mach plasma parallel flow is observed. Static pressure decreasing while dynamic pressure increasing to keep the total pressure conservation is shown to be a possible cause of the high Mach parallel flow.
Simulation of interaction between dust particles and plasma sheath and its distribution
Authors: Wu Jing  , Liu Guo  , Yao Lie-Ming  , Duan Xu-Ru  ,   School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054, China;,   Southwestern Institute of Physics, Chengdu 610041, China
Published: December 2020

Collisionless steady plasma sheath model is taken into account to study the interaction between dusty particles and plasma sheath as well as the density distributions of electrons, ions and dusty particles. Numerical simulation results are obtained, showing that the ability of an isolated charge to absorb electrons weakens with the increase of dusty particle density and its temperature, while the collective effect strengthens with the radius of dusty particle. Simultaneously, Bohm velocity and the sheath thickness are also greatly affected. The sheath potential decreases significantly and the E-field is stronger near the electrode. In addition, the densities of electrons and ions reduce exponentially but the dusty particle has a critical value. The three particles satisfy the quasi-neutrality condition.
The fluorescence feature of plasma induced by femtosecond laser pulses in air
Authors: Guo Kai-Min  , Gao Xun  , Hao Zuo-Qiang  , Lu Yi  , Sun Chang-Kai  , Lin Jing-Quan  ,   School of Science, Changchun University of Science and Technology, Changchun 130022, China;,   School of Physical Science and Technology, Baotou Teachers College, Baotou 014030, China
Published: December 2020

Effects of focusing conditions on femtosecond laser induced plasma fluorescence in air are investigated by using different focal length lenses. Under the tightly focusing condition, the fluorescence spectra are composed mainly of continuous spectrum and line spectra from N and O atoms, which is due to the higher laser intensity and corresponding higher electron density than those in the case of weakly focused laser beam. In the latter case, only line spectra from air molecules are observed. Besides, the intensity of line spectrum as a function of propagation distance is measured, which reveals the evolution of the plasma filaments.
Study on the preparation and properties of polyparaphenylene/LiNi0.5Fe2O4 anocomposite thermoelectric materials
Authors: Wu Zi-Hua  , Xie Hua-Qing  ,   School of Urban Development and Environmental Engineering, Shanghai Second Polytechnic University, Shanghai 201209, China
Published: December 2020

Polyparaphenylene/LiNi-ferrite nanocomposites are prepared by a novel rheological phase reaction method. The thermoelectric properties of the as-prepared nanocomposites are characterized and the effect of spark plasma sintering (SPS) conditions is investigated. The TEM images show that the size of LiNi-ferrite is around 100300 nm and the polyparaphenylene has diffused boundaries outside it. The negative value of Seebeck coefficient confirms the n-type conduction, and the n-type conduction is attributed to hopping of electrons from Fe2+ to Fe3+ ions. It is found that the electrical conductivity of nanocomposite does not change with sintering time whereas the Seebeck coefficient decreases and thermal conductivity increases with sintering time. Therefore the figure of merit decreases. Because of the high electrical conductivity and low thermal conductivity of organic material and high Seebeck coefficient of inorganic material, the figure of merit of nanocomposites is improved.
Electronic structure and optical properties of 0.5NdAlO3-0.5CaTiO3 from first-principles calculation
Authors: Yang Chun-Yan  , Zhang Rong  , Zhang Li-Min  , Ke Xiang-Wei  ,   School of Science, Northwestern Polytechnical University, Key Laboratory of Space Applied Physics and Chemistry, Ministry of Education, Xi’an 710072, China
Published: December 2020

The optimized crystal structure, energy band, density of states, and optical properties of 0.5NdAlO3-0.5CaTiO3 are calculated by the plane wave ultrasoft pseudopotential method based on the first-principles density functional theory. The optimized crystal parameters are in good agreement with the experimental ones and the errors are less than 1%. The calculated energy band results indicate that 0.5NdAlO3-0.5CaTiO3 has an indirect band gap of 0.52 eV. The energy band near Fermi level is determined by the density of states of Nd-4f, O-2p, Nd-4p, Al-3p, Ti-4d electrons. Moreover, the dielectric function, reflectivity and refractive index of 0.5NdAlO3-0.5CaTiO3 are also calculated.
Mechanism of current injection in the process of wire electrical explosion
Authors: Bi Xue-Song  , Zhu Liang  , Yang Fu-Long  ,   State Key Laboratory of Gansu Advanced Nonferrous Metal Materials, Lanzhou University of Technology, Lanzhou 730050, China;,   College of Electrical and Information Engineering, Lanzhou University of Technology, Lanzhou 730050, China
Published: December 2020

In the process of nanopowder production by the wire electrical explosion, the ablation of electrodes and the formation of micron-size particles are directly influenced by the way the current is injected into the metal wire from the electrodes. Through the channels which are provided by the contact between the electrodes and the wire ends, as well as the breakdown between them, a series of experiments of electrical explosion is carried out. Results show that the photocurrent detected by photodiodes at the wire ends almost occurs simultaneously with the circuit discharge current, however it at the central section lags behind the circuit discharge current obviously. The initial explosion product of the wire ends is liquid, and that of the other parts of wire is gas. Those results indicate that when the current folows into the contact, the phenomenon of gas discharge also occurs at the wire ends. Because the plasma provides another current path, the energy density of the wire ends is decreased. Hence, the wire ends cannot explode and form remainder on the electrodes. When the current flows into the breakdown, the electrodes ablated is slightly obvious, and there was no remainder on the electrodes.
Synthesis of Cr-doped ZnO diluted magnetic semiconductor by hydrothermal method under pulsed magnetic field
Authors: Zhu Ming-Yuan  , Liu Cong  , Bo Wei-Qiang  , Shu Jia-Wu  , Hu Ye-Min  , Jin Hong-Ming  , Wang Shi-Wei  , Li Ying  ,   Laboratory for Microstructures/School of Materials Science and Engineering, Shanghai University, Shanghai 200072, China
Published: December 2020

In this study, zinc chloride, chromic chloride, ammonium hydroxide and ammonium chloride are used as the source materials to prepare the crystalline Cr-doped ZnO diluted magnetic semiconductor by the hydrothermal method under a 4-T pulsed magnetic field. The structures and the morphologies of the samples are characterized by X-ray diffraction and scanning electron microscope. The magnetic analysis of the specimens is performed by vibrating sample magnetometer. The effects of pulsed magnetic field on the microstructure and the magnetic properties of the Cr-doped ZnO are discussed. The result indicates that all the samples still have hexagonal wurtzite structures. The pulsed magnetic field is conducive to promote the crystal growth orientation. The sample fabricated under pulsed magnetic field exhibits good room temperature ferromagnetism. The saturation magnetization is 0.068 emu/g. However, the sample synthesized without magnetic field shows paramagnetism at room temperature. The Curie temperature (Tc) of the Cr-doped ZnO is increased by 16 K through the pulsed magnetic field processing.
The damage effect and mechanism of the bipolar transistor caused by microwaves
Authors: Ma Zhen-Yang  , Chai Chang-Chun  , Ren Xing-Rong  , Yang Yin-Tang  , Chen Bin  ,   School of Microelectronics, Xidian University, Key Lab of Ministry of Education for Wide Band-Gap Semiconductor Materials and Devices, Xi'an 710071, China
Published: December 2020

Combining self-heating effect, mobility degradation in high electric field and avalanche generation effect, a two-dimensional electro-thermal model of the typical silicon-based n+-p-n-n+ structure bipolar transistor induced by high power microwave is established in this paper. By analyzing the variations of device internal distributions of the electric field, the current density and the temperature with time, a detailed investigation of the damage effect and the mechanism of the bipolar transistor under the injection of 1GHz equivalent voltage signals from the base and collector is performed. The results show that temperature elevation occurs in the negative half-period and the maximum temperature falls slightly in the positive half-period when the signals are injected from the collector. Compared with the former, device damage occurs easily with the signals injected from the base. Specifically, the base-emitter junction is susceptible to damage. The damage results caused by two large-amplitude signals with initial phases of 0 and respectively indicate that the injected signal with an initial phase of is liable to cause device damage. Meanwhile, the emitter series resistance can enhance the capability of the device to withstand microwave damage effectively.
A Monte Carlo simulation of secondary electron transport in diamond
Authors: Li Peng  , Xu Zhou  , Li Ming  , Yang Xing-Fan  ,   Institute of Applied Electronics, China Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

The diamond-amplifier photocathode (DAP) offers a new widely applicable way to generate high average-current, high brightness, and low thermal emittance electron beams. Physical processes with multiple parameters are important for the design of a reliable and efficient DAP. To perfom a study in-depth, a 2D Monte Carlo model in MATLAB frame is built to simulate the secondary electron transport in diamond. This simulation gives some proofs that the drift velocity is sensitive to diamond temperature and electric field applied, but not sensitive to the low impurity density(1017/cm-3). As an appropriate result, the saturation velocity of secondary electron reaches 1.88?107 cm/s, and mobility without applied field is 3732 cm2 /V.s. In addition, some properties of a secondary electron bunch transported in diamond are discussed, which indicate that the effect of space charge under our considered electron cloud density is small.
Internal layer solution of singularly perturbed optimal control problem
Authors: Wu Li-Meng  , Ni Ming-Kang  ,   Department of Mathematics, East China Normal University, Shanghai 200241, China
Published: December 2020

A class of singularly perturbed optimal control problem is studied by direct scheme method, which is based on the boundary function method. The internal layer solution is proved to be existing, and the uniformly valid asymptotic solution for the singularly perturbed optimal control problem is constructed.
Research of one-dimensional discrete chaotic system constructed by the hybrid circuits of single-electron transistor and metal oxide semiconductor
Authors: Feng Chao-Wen  , Cai Li  , Yang Xiao-Kuo  , Kang Qiang  , Peng Wei-Dong  , Bai Peng  ,   College of Science, Air Force Engineering University, Xi'an 710051, China;,   Department of Science Research, Air Force Engineering University, Xi'an 710051, China;,   Research Center of Integrated Electronic Information System, Air Force Engineering University, Xi'an 710051, China
Published: December 2020

A one-dimensional discrete chaotic system is constructed based on the hybrid architecture of single-electron transistor and metal oxide semiconductor in this paper. Voltage transfer characteristics of the parallel architecture of single-electron transistor and metal oxide semiconductor are investigated, and the corresponding N-shape piecewise linear function model is established. Based on this model a one-dimensional discrete mapping system is first constructed, the dynamics of the system is then analyzed including one-dimensional mapping process, bifurcation diagram and Lyapunov exponent spectrum and the corresponding discrete chaotic system is finally designed through the electronic circuits of the hybrid architecture. The simulation result is consistent with the theoretical analysis. All these indicate that discrete chaotic system designed by the hybrid architecture of single-electron transistor and metal oxide semiconductor has some advantages such as simple circuit structure and low power dissipation, which are good for the integration and application of chaotic system.
Identification of a stochastic neural firing rhythm lying in period-adding bifurcation and resembling chaos
Authors: Gu Hua-Guang  , Xi Lei  , Jia Bing  ,   College of Physics and Information Technology, Shaanxi Normal University, Xi'an 710062, China;,   College of Life Sciences, Shaanxi Normal University, Xi’an 710062, China
Published: December 2020

To identify non-periodic neural rhythm to be chaos or stochasticity has been an important scientific thesis. A kind of non-periodic spontaneous firing pattern, whose behavior is transition between period-k burst in a string and period-k+1 burst in a string (k=1,2), lying between period-k bursting pattern and period-k+1 bursting pattern, is found in the experimental neural pacemaker. The deterministic structures of the firing are identified by nonlinear prediction and first return map of the interspike intervals (ISIs) series. The co-existence of the period-k bursting and period-k+1 bursting is manifested in the deterministic theoretical neuronal model, Chay model. Non-periodic firing patterns similar to the experimental observation are simulated in the co-existing parameter region, implying that the firing pattern is transition between two kinds of bursts induced by noise. A binary series can be acquired by transforming two kinds of bursts to symbols 0 and 1, respectively. The stochastic dynamics within the transitions between two kinds of bursts are detected by probability analysis on the binary series. It not only shows that the rhythm is stochastic firing with deterministic structures instead of chaos, but also provides the typical examples and effective methods to intensively identify the chaotic and stochastic firing patterns in a real nervous system.
A chaos synchronization method based on amplitude
Authors: Tang Liang-Rui  , Fan Bing  , Kang Zhong-Miao  ,   School of Electric and Electronic Engineering, North China Electric Power University, Beijing 102206, China
Published: December 2020

A three-dimensional chaotic system is presented. The equilibrium point, the chaotic attractor and the Lyapunov exponent are investigated. According to the chaotic system, we propose a novel chaos synchronization method in which only the amplitude of chaotic signal is used to realize chaos synchronization. This feature can be used in chaotic communication system to improve the communication quality and speed. By computing the conditional Lyapunov exponents and numerical simulation the synchronization method is proved to be feasible and effective. The synchronous speed of the method is the same as that of the traditional linear feedback method.
Performance analysis of a quantum heat engine working with a particle in a one-dimensional harmonic trap
Authors: Wang Jian-Hui  , Xiong Shuang-Quan  , He Ji-Zhou  , Liu Jiang-Tao  ,   Department of Physics, Nanchang University, Nanchang 330031, China
Published: December 2020

A heat engine model of a sing particle confined in a one-dimensional harmonic trap is established. The model, as a quantum-mechanical analog of the Carnot engine, does work to outside when both the width of the potential and the quantum state change very slowly. On the assumption that the width of the potential moves at a very slow speed and the heat leakage is included, we derive the general expressions for several performance parameters, such as work, power output, efficiency, etc. We find the optimally operating regions and the optimal values of performance parameters of the heat engine cycle.
Density functional study on the geometric property of MnxSny(x=2,3,4; y=18,24,30)
Authors: Chen Xuan  , Yuan Yong-Bo  , Deng Kai-Ming  , Xiao Chuan-Yun  , Lu Rui-Feng  , Kan Er-Jun  ,   School of Science, Nanjing University of Science and Technology, Nanjing 210094, China;,   School of Science, University of Science and Technology of People's Liberation Army, Nanjing 211101, China
Published: December 2020

The geometric structures of the MnxSny (x=2,3,4; y=18,24,30) clusters are studied using the density functional theory method. The geometric optimization shows that the favourite structures of MnxSn6x+6 (x=2,3,4) are D3d single-cage structures which encapsulate Mn atoms, i.e. Mn2Sn18, Mn3Sn24 and Mn4Sn30.However the favourite structures of MnxSn6x+12 (x=2,3) are two-cage structures, i.e. MnSn12-MnSn12 and MnSn12-Mn2Sn18.Thus, it is promising to form new one-dimensional nonawires of MnxSny heterostructures by controlling the number of Mn atoms.
An electromagnetic inverse scattering approach based on support vector machine
Authors: Wang Fang-Fang  , Zhang Ye-Rong  ,   School of Electronic Science and Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210003, China
Published: December 2020

In order to solve electromagnetic inverse scattering problem, a real-time inverse scattering method is proposed. This technique converts the inverse scattering problem into a regressed one using support vector machine (SVM). Electromagnetic inverse scattering method based on the SVM deals with nonlinearity and ill-posedness inherent in the inverse scattering problem successfully. The feasibility and the validity are tested by making use of simulating through-wall problem, and the results demonstrate that this approach can detect and position the targets behind the wall, no matter whether there exists noise or not. In the through-wall scenario, the influence of the number of sampling positions of receiving antenna on the predicted results is discussed using the predicted model of SVM. In the end, the predicted errors are analyzed and investigated in the multiple source scenario. The results show that this kind of setting is helpful for target identification in through-wall problem.
Multiple scattering spectra through fog particles in the ellipsoidal model
Authors: Dai Bing  , Yuan Yin-Nan  , Mei De-Qing  , Jiang Jun-Kang  , Dai Shan-Shan  ,   School of Science, Nantong University, Nantong 226019, China;,   School of Mechanical Engineering, Nantong University, Nantong 226019, China;,   School of Automobile and Traffic Engineering, Jiangsu University, Zhenjiang 212013, China
Published: December 2020

Because of the properties of non-sphericity and multiple scattering of fog particles and the effects of geometrical optics, the light scattering through fog has become a difficult problem. In this paper, we establish an ellipsoidal model of fog particles. On the basis of radiative-transfer equation and with the consideration of the effects of geometrical optics, we obtain a formula of calculating multiple light scattering intensity through the fog particles with different sizes and different shape distributions. Our results are in agreement with the earlier results in two special cases, which verifies that our method is reliable. The calculations show that scattering spectra through the ellipsoidal fog particles present elliptical feature, which is different from circular feature for random orientation non-spherical particles. At the different orientation angles the angular distributions of the light intensity are different, and this difference becomes smaller with the shape ratio approaching to 1. The stripes of the scattering spectra progressively disappear with the increase of optical thickness, which is different from the case of single-scattering. At different orientation angles and observation angles, the scattering intensities always first increase then decrease with the increase of optical thickness for the fog particles of the different size distributions and different shape ratio distributions, and a maximal intensity occurs at =1.03.0. The calculations also indicate that the scattering spectra of actual fog particles present the turbid pattern around the central light speckle because of wide size distribution in many cases.
Photonic generation and transmission of chaotic ultra wideband signals
Authors: Liu Liu  , Zheng Jian-Yu  , Zhang Ming-Jiang  , Meng Li-Na  , Zhang Zhao-Xia  , Wang Yun-Cai  ,   Institute of Optoelectronic Engineering, Taiyuan University of Technology, Taiyuan 030024, China;,   State Key Laboratory of Millimeter Waves, Southeast University, Nanjing 210096, China
Published: December 2020

We propose and experimentally demonstrate a chaotic ultra wideband (UWB) over fiber link based on optical feedback laser diode, in which UWB signals are generated and transmitted at three different bit rates of 360, 720 Mbit/s, and 1.44 Gbit/s respectively. Without utilizing any dispersion compensation module, the signal at a bit rate of 1.44 Gbit/s is detected using a digital signal processing receiver after 10 km fiber and 0.6 m wireless channel transmission. The power spectrum does not have any discrete spectral line because of the random output of the chaotic pulses, which means that the harmful effects of discrete spectral lines could be avoided with this method.
Influence of temporal error with different pulse shapes on coherent beam combination system
Authors: Su Rong-Tao  , Zhou Pu  , Wang Xiao-Lin  , Ji Xiang  , Xu Xiao-Jun  ,   College of Optic-electric Science and Engineering, National University of Defense Technology, Changsha 410073, China
Published: December 2020

Coherent beam combination of fiber laser array is an important technology for high-power output fiber laser systems. However, the coherent beam combination is influenced by temporal error, which always exists in the laser array. The coherent beam combination of pulse fiber lasers in the presence of temporal error is investigated in theory in this paper. The effects of pulse shape and temporal error on the coherently combined beam are studied. The characteristics of combined beam, i.e. pulse shape, peak power, far-field pattern and power in barrel (PIB) are calculated and analyzed when the pulse shapes (including square, triangle and sine) and temporal errors are different. It is revealed that for coherently combining square pulse lasers, the pulse shape of the combined beam changes acutely because of temporal error, and the far-field pattern and PIB change proportionally with temporal error increasing; for coherently combining triangle pulse lasers, the pulse shape and the peak power of the combined beam are acutely influenced by temporal error, and the far-field pattern and the PIB change acutely when temporal error is large. It is revealed that coherently combined beam of sinusoidal pulse lasers has good characteristics when two pulse laser with sinusoidal pulse shapes are coherently combined and the time delay between the two pulses is less than 10% of pulse duration.