bluuebunny/crossref_metadata_2025 huggingface dataset:
Dependence of annealing temperatures on the optimized resistive switching behavior from SiOx (x=1.3) films
Authors: Ren Sheng  , Ma Zhong-Yuan  , Jiang Xiao-Fan  , Wang Yue-Fei  , Xia Guo-Yin  , Chen Kun-Ji  , Huang Xin-Fan  , Xu Jun  , Xu Ling  , Li Wei  , Feng Duan  ,   National Laboratory of Solid State Microstructures, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, China
Published: December 2020

SiOx films (x=1.3) are deposited on the silicon substrates by electron beam evaporation. The resistive switching behaviors from the device consisting of indium tin oxide (ITO)/SiOx/Si/Al with annealed SiOx layer as the resistive layer are investigated. It is found that on/off ratio of the device increases with the annealing temperature rising. The maximum on/off ratio reaches 109. The analyses of X-ray photoelectron spectrum and electron paramagnetic resonance spectrum reveal that the silicon dangling bonds in different valence states can be formed at different annealing temperatures, which is the main source of the conducting filament pathway. The result of ellipsometer indicates that the increase of refractive index of annealed SiOx film leads to the increase of the resistance of high resistance state.
Band offsets of ZnO/PbTe heterostructure determined by synchrotron radiation photoelectron spectroscopy
Authors: Cai Chun-Feng  , Zhang Bing-Po  , Li Rui-Feng  , Xu Tian-Ning  , Bi Gang  , Wu Hui-Zhen  , Zhang Wen-Hua  , Zhu Jun-Fa  ,   School of Information and Electrical Engineering, Zhejiang University City College, Hangzhou 310015, China;,   Department of Physics, Zhejiang University, Hangzhou 310058, China;,   Department of Science, Zhejiang Colloge of Zhejiang University of Technology, Hangzhou 310024, China;,   National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, China
Published: December 2020

Accurate determination of the band offsets of a heterostructure is essential to its study and application. In this paper, we use synchrotron radiation photoelectron spectroscopy to determine the band offset of ZnO/PbTe heterostructure. The valence band offset is 2.56 eV, and the conduction band offset is 0.49 eV, which indicates that the heterostructure has a type-I band alignment. By performing the depth scanning measurement, we find there are two bonding structures at the interface of ZnO/PbTe heterostructure, corresponding to Pb-O bonding (low energy side) and Pb-Te bonding (high energy side). At the interface of ZnO/PbTe heterostructure, the conduction band offset is much smaller than the valence band offset which is conducive to the transportation of excited electrons in PbTe source layer to ZnO electrode. Due to the unique band structure the ZnO/PbTe heterostructure has potential applications in the fabrication of high efficiency solar cells, mid infrared detectors and lasers.
Influence of interfacial electron transfer on fluorescence blinking of quantum dots
Authors: Wu Jian-Fang  , Zhang Guo-Feng  , Chen Rui-Yun  , Qin Cheng-Bin  , Xiao Lian-Tuan  , Jia Suo-Tang  ,   State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser Spectrum, Shanxi University, Taiyuan 030006, China
Published: December 2020

The fluorescence blinking characteristics of the single CdSe/ZnS core/shell quantum dots (QDs) absorbed on the cover glass surface, indium-tin oxide (ITO) nanoparticles, and polymethyl methacrylate (PMMA) film surface are measured by a laser scanning confocal fluorescence microscopy. It is found that all the distributions of bright state duration time of QDs on the three different interfaces can be described by a truncated power law P(t)∝ t-αexp(-t/μ). The statistical on-time durations of single QDs absorbed on the ITO nanoparticles is shorter than on the glass. In addition, the on-time duration with single QDs absorbed on the PMMA is longer than on the others. These differences can be attributed to the diverse interfacial electron transfers between QD and different materials.
Shock induced Nd2Fe14B magnetic transition based on molecular field theory analysis
Authors: Lu Feng  , Chen Lang  , Feng Chang-Gen  ,   State Key Laboratory of Explosion Science and Technology, School of Mechanical Engineering, Beijing Institute of Technology, Beijing 100081, China
Published: December 2020

According to the shock wave experiment on the Nd2Fe14B ferromagnet, the relationship between pressure and temperature on the shock front is calculated in a pressure range from 3.3 GPa to 7.2 GPa. In order to analyze the magnetic transition mechanism of Nd2Fe14B under different temperatures and applied pressures, the equivalent pressure field is introduced to improve the two-sublattice model based on the molecular field theory. The pressure dependence of magnetostriction coefficient, susceptibility, magnetization, and Curie temperature of Nd2Fe14B are calculated. The criteria of the ferromagnetic-paramagnetic phase transition occurring in Nd2Fe14B at different temperatures and pressures are obtained. The results indicate that the Curie temperature of Nd2Fe14B decreases as pressure increases. The Curie temperature reduces from 584 K at 0 GPa to 298 K at 1.142 GPa. With the increasing of pressure, the magnetization of Nd2Fe14B declines. The critical demagnetization pressure of Nd2Fe14B also decreases with the increasing of temperature. In a pressure region from 3.3 GPa to 7.2 GPa, there appears the pressure induced ferromagnetic-paramagnetic phase transition of Nd2Fe14B.
Micromagnetic modeling of L10-ordered FePtmagnetic thin films
Authors: Li Zheng-Hua  , Li Xiang  ,   School of Physics and Materials Engineering, Dalian Nationalities University, Dalian 116600, China;,   School of Materials Science and Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China
Published: December 2020

The L10-ordered FePt films are promising materials for ultra high density magnetic recording media due to their high magnetic anisotropies. In this work, the L10-ordered FePt thin films are prepared by magnetron sputtering on CrW underlayer. A three-dimensional micromagnetic model, based on the symmetry of the L10 phase, is set up for FePt perpendicular media. According to the mismatch between the underlayer and FePt magnetic layer, a residual tensile stress is applied in the film plane. The simulated M-H loops accord well with the experimental results. The tetragonal crystalline anisotropy, especially high in-plane anisotropy, could enlarge the in-plane coercivity. The simulated perpendicular and longitudinal loops each have an open up in the tail, which is mainly due to the magnetostriction of the L10 phase.
Influence of vacancy on spontaneous polarization of wurtzite AlN： a maximally localized Wannierfunction study
Authors: Niu Hai-Bo  , Chen Guang-De  , Wu Ye-Long  , Ye Hong-Gang  ,   Department of Applied Physics, Xi'an Jiaotong University, Xi'an 710049, China;,   Teaching Center of Physics, Xi'an Jiaotong University City College, Xi'an 710018, China
Published: December 2020

By using first-principles plane-wave ultrasoft pseudopotential method based on the density functional theory, the maximally localized Wannier functions of N vacancy and Al vacancy with different charge states in wurtzite AlN are calculated. With the shape and center of the computed Wannier function, the electronic structure and the spontaneous polarization of vacancy are studied respectively. The results show that N–Al bond possesses a large ionicity. It is found that the electrons of the dangling bonds displace to the positions of vacancies in N vacancy structure, while in Al vacancy structure the electrons of dangling bonds keep away from vacancies and move to the other side of N atoms. Since the vacancy breaks the centrosymmetry of the [1010] and [1210] orientations, the polarization will be induced in these two directions, and the polarization will increase as the charge increases. In the [0001] orientation, the spontaneous polarization in N vacancy will reverse as charge increases because of the dramatic variation of the electronic structure. Contrary to N vacancy, the reversion does not occur although the spontaneous polarization of Al vacancy increases as charge increases.
Solvent effects on the electron-vibration coupling constant of β-carotene
Authors: Xu Sheng-Nan  , Liu Tian-Yuan  , Sun Mei-Jiao  , Li Shuo  , Fang Wen-Hui  , Sun Cheng-Lin  , Li Zuo-Wei  ,   State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012, China;,   College of Physics, Jilin University, Changchun 130012, China
Published: December 2020

Solvent effect plays an important role in determining electron-vibration coupling constant, however, the physical properties of solvent effects and the relationship between them still need to be investigated. We measure the UV-visible absorption and Raman spectra of β-carotene in 10 typical solvents. The results show that polarizability and dielectric constant of solvent have a significant effect on the electron-vibration coupling constant of β-carotene. With the increase of polarizability, no matter whether the solvent is of polarity, Huang-Ryes factor and the electron-vibration coupling constant of β-carotene decrease and the Raman scattering cross section of β-carotene increases. As to nonpolar solvent, Huang-Ryes factor and the electron-vibration coupling constant of β-carotene decrease with increasing the dielectric constant of the solvent. For polar solvent, no good regularity is obtained. In this paper, the regularity of solvent effect on the electron-vibration coupling constant is presented, which can provide a reference for how to choose the solvent in studying the electron-vibration coupling constant.
Organic light-emitting devices based on PCDTBT as emitting layer
Authors: Chen Hai-Tao  , Xu Zheng  , Zhao Su-Ling  , Zhao Ling  , Liu Zhi-Min  , Gao Song  , Yang Yi-Fan  , Liu Zhi-Fang  , Shen Chong-Yu  , Xu Xu-Rong  ,   Key Laboratory of Luminescence and Optical Information (Beijing Jiaotong University), Ministry of Education, Beijing 100044, China;,   Institute of Optoelectronics Technology, Beijing Jiaotong University, Beijing 100044, China
Published: December 2020

Here we report a red organic electroluminescent device (OLED) with an emission wavelength at 705 nm in which PCDTBT is used as an emitting layer with the structure ITO/PEDOT:PSS/PCDTBT/BCP/LiF/Al. The device shows good performances such as an onset voltage of 2 V, a maximum brightness of 29000 cd/m2 at 9 V and a maximum current efficiency of 3.5 cd/A. The effects of annealing on the luminescent property of the device are studied at different temperatures. The experimental results suggest that the device presents the best performance at an annealing temperature of 50℃, then the performance decreases with annealing temperature increasing. We find that relatively low temperature annealing is beneficial to the solvent evaporation, and the high temperature annealing is conducible to reducing the coherence length of the π-π stacking, which results in the degradation of the performance of the device.
Lithium intercalation properties of SnSb/C composite in carbonthermal reduction as the anode material for lithium ion battery
Authors: Li Juan  , Ru Qiang  , Hu She-Jun  , Guo Ling-Yun  ,   Key Laboratory of Quantum Engineering and Quantum Materials in Guangdong Province, School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou 510006, China;,   Engineering Research Center of Materials and Technology for Electrochemical Energy Storage of Ministry of Education, Guangzhou 510006, China
Published: December 2020

The SnSb/C composite material is prepared by using the carbonthermal reduction to deal with the mixture of SnO2 and SbO3, respectively with different carbon reductant-glucose and mesocarbon microbead (MCMB). The morphologies and electrochemical properties of two kinds of structures of SnSb/C composite are compared. To characterize the phase and morphology of the composite material, X-ray diffraction, Raman spectra and scanning electron microscope are used. The current charge and discharge, cyclic voltammograms and AC impedancetests are also used to test the electrochemical performance of SnSb/C. The experimental results show that a kind of core-shell structure, of which the alloy particle serves as the core and the pyrolytic carbon as the outside shell, is formed when the glucose is used as the reducing agent. The first discharge specific capacity is 793.379 mA·h/g and it is still kept at 449.987 mA·h/g after 50 cycles. However, when the MCMB is used as the reducing agent, there are only a few of alloy particles attaching to the surface of MCMB, and it is not a kind of core-shell structure but a mixture of alloy particles and MCMB spheres. Its initial discharge specific capacity is 1164.938 mA·h/g, and after 50 cycles it is only 290.807 mA·h/g.
Cyclical game coupling with Levy flight and Brownian motion and stable coexistence conditions of species
Authors: Wang Dong  , Tang Chang-Qing  , Tian Bao-Guo  , Qu Liang-Sheng  , Zhang Jin-Chun  , Di Zeng-Ru  ,   Department of Basic Science, Naval Aeronautical and Astronautical University, Yantai 264001, China;,   School of Systems Science, Beijing Normal University, Beijing 100875, China;,   Administrant Brigade of Postgraduate, Naval Aeronautical and Astronautical University, Yantai 264001, China
Published: December 2020

Cyclical game is often used to study the biodiversity in ecosystem. However, the interaction distance mode considered in previous studies of cyclical game is only the interaction between nearest neighbors, a fixed distance, or a random value of fixed distance among the individuals of species. This is not consistent with the actual situation. In this paper, considering the fact that Levy flight and Brownian motion widespreadly exist in ecosystem, and comprehensively considering the nearest-neighbor-interaction and long-range-interaction given by Levy flight and Brownian motion, the cyclical game and conditions of maintaining biodiversity are investigated. The critical relation of maximal step length of flight versus choosing probability is presented, including Logistic and exponent relations. Further the critical relation between power-law exponent and choosing probability is found. The condition of maintaining species coexistence is also found.
A topological reconfiguration method for enhancing networks survivability with limited resources
Authors: Li Li  , Zheng Qing-Hua  , Guan Xiao-Hong  ,   Key Laboratory for Intelligent Network and Network Security of Ministry of Education, Xi'an Jiaotong University, Xi'an 710049, China;,   School of Computer Science and Technology, Shaanxi Normal University, Xi'an 710062, China
Published: December 2020

For an existing network and in limited link addition resources, it is a valuable task to determine optimally the new link resources such that the resulting network is the most robust and efficient. In this paper, we investigate the modeling and analysing of network topological reconfiguration optimization with limited link addition (NTRLA). The network survivability metric is proposed to quantitatively characterize the robustness and efficiency of a network. To approximately solve the NTRLA problem, a heuristic algorithm based on the preferential configuration of enhanced node-protecting cycles (PCNC) is proposed. Simulation results show that the PCNC method can effectively improve the network robustness and communication efficiency at the cost of the least added link resources under either random or targeted attack.
Noether symmetry and Mei symmetry of a discrete holonomic mechanical system with variable mass
Authors: Wang Fei-Fei  , Fang Jian-Hui  , Wang Ying-Li  , Xu Rui-Li  ,   College of Science, China University of Petroleum, Qingdao 266555, China
Published: December 2020

This paper studies the Noether symmetry and Mei symmetry of a discrete holonomic mechanical system with variable mass. Firstly, by the difference discrete variation approach, the discrete equations of motion of the system are established. Secondly, the definitions of Noether symmetry and Mei symmetry are given, and the conditions under which the Noether conserved quantity can be induced by Noether symmetry and Mei symmetry are obtained. Finally, an example is discussed to illustrate these results.
Fast analysis of electromagnetic scattering characteristics in spatial and frequency domains based on compressive sensing
Authors: Chen Ming-Sheng  , Wang Shi-Wen  , Ma Tao  , Wu Xian-Liang  ,   School of Electronics and Information Engineering, Hefei Normal University, Hefei 230601, China;,   School of Electronics and Information Engineering, Anhui University, Hefei 230039, China
Published: December 2020

Method of moments (MOM) is a common numerical method for solving electromagnetics, which is used widely owing to its high accuracy. As the traditional MOM is applied to solving electromagnetic problem in both spatial and frequency domains, the matrix equation generated from the integral equation must be solved repeatedly since small spatial increments and frequency increments are both required. To resolve problems of this kind, the compressive sensing (CS) theory combined with the asymptotic waveform evaluation (AWE) is introduced to form a new efficient computational method. Firstly, a new incident source is constructed based on CS theory, in which much spatial information is included. Secondly, illuminated by the new incident source, the new equation is solved by AWE technique, and finally a fast implement is formed for solving electromagnetic scattering characteristics in both spatial and frequency domains.
Precise modeling and dynamic characteristics of valley V2 controlled Boost converter
Authors: He Sheng-Zhong  , Zhou Guo-Hua  , Xu Jian-Ping  , Wu Song-Rong  , Yan Tie-Sheng  , Zhang Xi  ,   School of Electrical Engineering, Southwest Jiaotong University, Chengdu 610031, China
Published: December 2020

A discrete iterative map model of valley V2 controlled Boost converter is established, based on which the bifurcation diagrams are obtained with the variation of input voltage, output capacitance and its equivalent series resistance (ESR). Jacobi matrix at a fixed point is also derived, and according to it, the converter stability is analyzed using characteristic values and maximum Lyapunov exponent, thus the correctness of bifurcation analysis is validated. The effect of input voltage, output capacitance and its ESR on the dynamic characteristics of valley V2 controlled Boost converter is mainly investigated. It is found that as the input voltage increases continuously, the valley V2 controlled Boost converter changes from continuous conduction mode (CCM) period-1 to CCM period-2 due to period-doubling bifurcation, and comes into CCM chaos due to border collision bifurcation. The converter has the same bifurcation routes at output capacitance and its ESR: with gradual reduction of output capacitance or its ESR, the valley V2 controlled Boost converter behaves the evolutive dynamic behavior from CCM period-1 to CCM period-2, CCM period-4, CCM period-8, and CCM chaos. Finally, the simulation and experimental circuits are set up, and the correctness of theoretical analysis is verified by simulation and experimental results.
Power output and efficiency of irreversible regenerative Stirling heat engine using generalized Redlich-Kwong gas as the working substance
Authors: Zheng Shi-Yan  ,   College of Physics and Information Engineering, Quanzhou Normal University, Quanzhou 362000, China;,   Key Laboratory of Functional Materials for Informatics, Fujian Province University, Quanzhou 362000, China
Published: December 2020

Performance of a generalized Redlich-Kwong gas Stirling heat engine is investigated, in which the multi-irreversibilities including thermal resistance, regenerative and heat leak losses are taken into account. General expressions for power output and efficiency of the Stirling heat engine are derived, and effects of the nonperfect regeneration and some important performance parameters such as the volume ratio and the temperature ratio are analyzed and discussed. Moreover, it is shown that the efficiency of the gas Stirling heat engine with perfect regeneration and no heat leak can reach that of the Carnot heat engine.
Ultra-thin multiband metamaterial absorber based on multi-order plasmon resonances
Authors: Wang Wen-Jie  , Wang Jia-Fu  , Yan Ming-Bao  , Lu Lei  , Ma Hua  , Qu Shao-Bo  , Chen Hong-Ya  , Xu Cui-Lian  ,   Science College, Air Force Engineering University, Xi'an 710051, China
Published: December 2020

In this paper, an ultra-thinspiral-structured metamaterial absorber is demonstrated both numerically and experimentally, whose thickness (1.034 mm) is about (1/60th, 1/44th, 1/32th, 1/23th, 1/21th) of the respective working wavelengths (4.81, 6.59, 9.16, 12.69 and 13.71 GHz). Simulation results show that the absorber can achieve absorption up to 94.41%, 99.89%, 99.73%, 99.26% and 99.41% at 4.81, 6.59, 9.16, 12.69 and 13.71 GHz respectively. Thus multi-band absorptions are realized. From the two aspects of surface current and power loss density, the mechanism of strong absorption is analyzed. Theoretical analysis shows that the multi-band absorption arises from multi-order plasmon resonances at five neighboring frequencies. Strong absorptions are induced due to strong electric resonances within/between the spiral structures. Design of the metamaterial absorber is simple and is easy to be implemented, so such absorbers may have application values in designing novel electromagnetic absorbers.
Analysis on threshold characteristics of a diode-pumped Cs vapor laser
Authors: Xu Yan  , Chen Fei  , Xie Ji-Jiang  , Li Dian-Jun  , Yang Gui-Long  , Guo Fei  , Guo Jin  ,   Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, State Key Laboratory of Laser Interaction with Matter, Changchun 130033, China;,   University of the Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

A rate equation model is established to describe the threshold characteristics of a diode-pumped Cs vapor laser in this paper. With the help of the numerical solution for the model, the influences of several parameters (waist position and waist radius of pump laser, length of vapor cell, and operating temperature) on the threshold pump power are analyzed. Results show that there are optimal values of the pump waist position and radius, vapor cell length and operating temperature to ensure a lowest threshold pump power. Besides, the decrease of divergence angle can reduce threshold pump power effectively. Simulation results are in good agreement with the experimental data. It is shown that the model can be used to reveal the threshold characteristics of diode-pumped alkali vapor laser and may serve as a theoretical guidance for the optimization design of this laser.
Study on coupling characteristics between bubble and complex walls at the same scale
Authors: Shi Dong-Yan  , Wang Zhi-Kai  , Zhang A-Man  ,   College of Mechanical and Electrical Engineering, Harbin Engineering University, Harbin 150001, China;,   College of Shipbuilding Engineering, Harbin Engineering University, Harbin 150001, China
Published: December 2020

A gas-liquid-solid three-phase coupling dynamic model is established using lattice Boltzmann method (LBM). Interaction between rising bubble and complex solid walls at the same scale is studied. Firstly, based on the viscous fluid theory, a group of lattice Boltzmann equations are developed to describe the gas-liquid two-phase campaign by considering the viscosity, surface tension, and gravity in the form of a LB discrete body force. At the same time, combined with the finite difference scheme, the half-way bounce back model in LBM is adopted to deal with the solid boundary condition. Then, under the conditions of different feature size ratios, the coupling characteristics between bubbles and plane wall, taking into consideration the effect of boundaries and curved wall, are studied using the newly built model. Results show that both the solid wall condition and the feature size ratio have significant nonlinear effects on bubble movement and topology changes. Finally, the effect of fluid properties on the coupling regularity of bubbles and complex walls is researched.
Synthesis of porous micro-sphere ZnO and its excellent sensing properties to acetone
Authors: Bo Xiao-Qing  , Liu Chang-Bai  , Li Hai-Ying  , Liu Li  , Guo Xin  , Liu Zhen  , Liu Li-Li  , Su Chang  ,   National Laboratory of Superhard Material, College of Physics, Jilin University, Changchun 130012, China;,   College of Electronic Science & Engineering, Jilin University, Changchun 130012, China
Published: December 2020

Porous micro-spheres of ZnO have been synthesized with Zn(NO3)26H2 O and urea as the raw materials and hexamine as a surfactant via a hydrothermal method. Structure, morphology, specific surface area, and pore size distribution of ZnO porous micro-sphere are characterized by X-ray diffraction, scanning electron microscopy, and micromeritics ASAP 2420 apparatus, respectively. Gas sensors are fabricated from the ZnO porous micro-spheres and their gas-sensing properties are measured. The gas sensitivity of sensor samples at different temperatures to acetone gas is examined. Results show that the sensitivity of ZnO porous micro-spheres sensors to 50 ppm acetone gas is 26.8 at 280 ℃, and the response and recovery durations are 4-10 seconds, respectively. Also, the sensor possesses an excelent selectivity for acetone.
Local structure distortion and the spin-Hamiltonian parameters for Fe3+-doped ZnGa2O4 crystal materials
Authors: Yang Zi-Yuan  ,   Department of Physics and Information Technology, Baoji University of Arts and Science, Baoji 721013, China
Published: December 2020

Relations between the spin-Hamiltonian (SH) parameters including the second-order zero-field splitting (ZFS) parameter D, the fourth-order ZFS parameter (a-F), the Zeeman g-factors: g//, g, g(=g//-g) and the structural parameters of ZnGa2O4:Fe3+ crystals have been established by means of the microscopic spin Hamiltonian theory and Newman's crystal field (CF) superposition model. On the basis of this, the SH parameters for Fe3+ magnetic ions in ZnGa2O4:Fe3+ crystals are investigated theoretically using the CFA/MSH (crystal field analysis/microscopic spin-Hamiltonian) software based on the full configuration complete diagonalization method. It is found that the theoretically calculated parameters including the ZFS parameters D, (a-F), and the Zeeman g-factors: g//, g, g(=g//-g) for ZnGa2O4:Fe3 + crystals are in good agreement with experimental data when taking into account the lattice distortions: R=0.0487 nm and =0.192. This investigation reveals that there is a slight local structure distortion due to Fe3 + ions in ZnGa2O4:Fe3+ crystals, but the site of Fe3+ still retains D3d symmetry. On the other hand, it is found for Fe3+ ions in ZnGa2O4:Fe3+ crystals that the contribution to the SH parameters from the spin-orbit (SO) mechanism is the most important one, whereas the contributions to the SH parameters from other four mechanisms, including the spin-spin (SS), spin-other-orbit (SOO), orbit-orbit (OO), and SO-SS-SOO-OO mechanisms, are small.
Effeet of Lu3+-doping on high-temperature electric and thermal transport properties of CdO
Authors: Dong Guo-Yi  , Li Long-Jiang  , Lü Qing  , Wang Shu-Fang  , Dai Shou-Yu  , Wang Jiang-Long  , Fu Guang-Sheng  ,   Hebei Key Laboratory of Optoelectronic Information Materials, the College of Physical Science and Technology, Hebei University, Baoding 071002, China
Published: December 2020

Cd1-xLuxO(x=0%, 0.1%, 0.5%, 0.75%, 1.0%, 1.25%, 1.5%, 2%) ceramics have been synthesized by the traditional solid phase sintering method; and the effects of Lu3+-doping on the electric and thermal transport properties of these samples are investigated. With the increase of Lu3+-doping concentration, the room temperature carrier concentration in Cd1-xLuxO increases while the mobility first increases and then decreases. In the measuring temperature range of 300 to 1000 K, the electric conductivity of Cd1-xLuxO exhibites a metallic conducting behavior, and both their electric conductivity and thermal conductivity increase with the Lu3+-doping concentration. The Seebeck coefficient S of Cd1-xLuxO is negative in the whole measuring temperature range, and the dependence of S on the carrier concentration can be describedby a free electron model.
Recesiation of GaAlAs photocathodes in an ultrahigh vacuum system
Authors: Zhang Yi-Jun  , Gan Zhuo-Xin  , Zhang Han  , Huang Fan  , Xu Yuan  , Feng Cheng  ,   Institute of Electronic Engineering and Optoelectronic Technology, Nanjing University of Science and Technology, Nanjing 210094, China
Published: December 2020

To seek a photocathode with good stability and repeatability in an ultrahigh vacuum system, activation and recesiation experiments are carried out on reflection-mode GaAlAs and GaAs photocathodes grown by metalorganic chemical vapor deposition, and the spectral response curves and photocurrent decay curves are measured after Cs/O activation and recesiation. Experimental results show that the photocurrent decay lifetime for GaAlAs photocathode illuminated by white light with an intensity of 100 lx is longer than that for GaAs photocathode after Cs/O activation and recesiation under ultrahigh vacuum condition. Moreover, GaAlAs photocathode exhibits a coincident blue-green response capability and a photocurrent decay lifetime after multiple recesiations, reflecting the superiority in stability and repeatability for GaAlAs photocathode operating in the vacuum system, and may provide an experimental guidance for exploring marine vacuum detectors and vacuum electron sources.
Trap, ignition, and diffusion combustion characteristics of active carbon micro-particles at a meso-scale studied by optical tweezers
Authors: Huang Xue-Feng  , Li Sheng-Ji  , Zhou Dong-Hui  , Zhao Guan-Jun  , Wang Guan-Qing  , Xu Jiang-Rong  ,   School of Science, Hangzhou Dianzi University, Hangzhou 310018, China;,   College of Materials and Environmental Engineering, Hangzhou Dianzi University, Hangzhou 310018, China
Published: December 2020

To study combustion characteristics of solid fuels at the meso-scale, this paper presents a study on trap, ignition, and diffusion combustion characteristics of active carbon micro-particles at a meso-scale by optical tweezers. In the meso-scale combustor, minimum trap power for active carbon micro-particles with a diameter of 7.0 m is 3.2 mW, and the trap velocity is in the range of 103.770.0 m/s. The active carbon micro-particles in static air flow can be ignited when the laser power is 3.2 mW. The effective diameter, perimeter, area and roundness of the particles have little effect on the minimum power for ignition. The ignition delay time is ～ 48 ms for active carbon micro-particles with a diameter of 3.0 m, and it will decrease till below 6 ms with increasing laser power. After ignited, the active carbon micro-particle shows flameless combustion first. The diffusion combustion velocity agrees with the diameter square linear-relationship, and the velocity is of 15.08.0 m/s. Then the active carbon micro-particle continues to carry out combustion reactions with bright flames repetitiously, and the flash frequency is 29.1 Hz. For the active carbon micro-particle with a diameter of 3.0 m, it can burn out thoroughly in an overall time ～ 0.648 s (including the heating and combustion processes). Results demonstrate that ignition of the active carbon micro-particle heated by high power density laser belongs to the combined ignition mode. Before volatile matter precipitates, the active carbon micro-particle is ignited heterogeneously and carries out a flameless combustion. However, after the volatile components are precipitated, it is ignited homogeneously, and the ombustion flame always shows a spheried shape.
Partitioning community structure in complex networks based on node dependent degree
Authors: Wang Xing-Yuan  , Zhao Zhong-Xiang  ,   Faculty of Electronic Information and Electrical Engineering, Dalian University of Technology, Dalian 116024, china
Published: December 2020

In this paper, we present a new approach to partitioning communities in a complex network via degree of dependence of nodes. We define the dependence degree of a node on its neighbors, the dependencetce degree and the conditional dependence degree of a node on a cluster. The main point of the approach is to partition the nodes, which have the biggest dependence degree and are only dependent on nodes, firstly to clusters, then to absorb nodes whose dependence degree or conditional dependence degree on cluster gets the right value, until all the nodes are partitioned to the right communities. The partition of our approach in some real-world network satisfies the definition of communities, and in the network whose communities are already known, our partition method fits the physical truth.
An improvement in fast radiative transfer calculation of FengYun satellite by Planck weighting correction
Authors: Ma Gang  , Zhang Peng  , Qi Cheng-Li  , Xu Na  , Dong Chao-Hua  ,   National Satellite Meteorological Center, BeiJing 100081, china
Published: December 2020

A unified regression method to calculate fast transmittance coefficients is used in fast radiative transfer calculation of satellite infrared channel by a convoluted transmittances database from LBL (Line_By_Line) model. Comparison is performed between the fast calculated brightness temperature and LBL calculations for VISSR/FY-2F and IRAS/FY-3B. The examination indicates that STD (Standard Deviation) of fast calculated brightness temperature in window channels are much larger than the values in sounding channels. The lower atmosphere the channel detects, the larger the STD is available. And the largest the STD is less than 0.4 K. In this paper, a discussion is given to the improvement of fast radiative transfer calculation brought about by Planck weighted correction for convoluted channels' transmittances. Analysis shows that overlap between 2350 cm-1 and spectral response filter of the channel is a requirement to the Planck weighted correction. It is shown that STDs of brightness temperature between LBL calculation and fast computation are decreased by 25% after Planck weighted correction. And the improvement is available only for such channels with an overlap between their filter function and 2350 cm-1. Also it is indicated that the improvement from Planck weighted correction could be used not only to the imaging channels that have wide spectral coverage, but also to the sounding channels with very narrow spectral fields.
Effect of bifocal lens on propagation of Bessel beam
Authors: Xie Xiao-Xia  , Wu Feng-Tie  , Li Dong  ,   Fujian Key Laboratory of Optical Beam Transmission and Transformation, College of Information Science and Engineering, Huaqiao University, Xiamen 361021, China
Published: December 2020

In this paper, we study the influence of the bifocal lens on the focusing properties of Bessel beam. Based on the generalized Huygens-Fresnel diffraction integral, a more general expression of the light intensity distribution of nonsymmetrical optical system which is described by 4×4 matrix is deduced. The optical field distribution of Bessel beam passing through bifocal lens is given and simulated numerically. The influence of the focal length of the bifocal lens on Bessel beam is analyzed in detail. The generalized expression of the light intensity distribution can involve three cases, i.e., ordinary lens, bifocal lens and cylindrical lens. The greater the astigmation, the poorer the bottle beam quality will be. The ability to imprison microscopic particles decreases.
Fault estimation for discrete switched system based on iterative learning
Authors: Cao Wei  , Guo Yuan  , Sun Ming  ,   College of Computer and Control Engineering, Qiqihar University, Qiqihar 161006, China
Published: December 2020

Aiming at the problem of fault estimation in a class of time-varying discrete switched system with arbitrary sequence, in this paper we propose a novel fault estimation algorithm. The algorithm uses the introduced virtual fault signal to construct fault estimator, and uses the residual signal to modify the introduced virtual fault step by step through using the iterative learning method and making the virtual fault gradually approach to the actual fault by increasing the iterative number. The convergence of the algorithm in each subinterval is strictly proven by the use of contraction mapping method, and the convergent condition of the algorithm is provided. Theoretical analyses indicate that the proposed algorithm can estimate different types of faults occurring in a switched system accurately in a finite interval. Finally, the validity of the algorithm is verified by simulations.
Nonlocal symmetry and explicit solutions of the Kaup-Kupershmidt equation
Authors: Wang Zhen-Li  , Liu Xi-Qiang  ,   School of Mathematical Sciences, Liaocheng University, Liaocheng 252059, China
Published: December 2020

In this paper, using the mechanization-method obtained nonlocal symmetry and reduction of the Kaup-Kupershmidt equation and solving the reduction equation, new solutions to the equation are obtained.
New studies of tunneling radiation from Kerr-Newman black holes
Authors: Wu Di  , Zhu Xiao-Dan  , Wu Shuang-Qing  ,   College of Physics and Electric Information, China West Normal University, Nanchong 637002, China
Published: December 2020

In the paper [Wu D et al. Sci. sin. G: Phys. Mech. Astron. 43 115], starting from the action of a massive particle's Lagrangian, we have made a new, unified derivation of the timelike and null geodesics of a rotating Kerr black hole. Our results demonstrate that one need not constrain himself to adopt the dragging coordinate system to investigate the tunneling radiation of rotating black holes. That work completely overcomes all shortcomings existing in the previous related researches, thus making Parikh-Wilczek's semi-classical approach more perfect and consistent. In this paper, we extend that work to the case of a rotating charged black hole to present a new derivation of the geodesic equation of a massive charged particle in the Kerr-Newman black hole and to reinvestigate its tunneling radiation.
Complicated behavior and mechanism of Chen system with slowly variable control
Authors: Zhang Xiao-Fang  , Han Qing-Zhen  , Chen Xiao-Ke  , Bi Qin-Sheng  ,   Faculty of Civil Engineering and Mechanics, Jiangsu University, Zhenjiang 212013, China
Published: December 2020

Since most of the work relevant to the control of Chen system is based on the same time scale, and the results associated with the coupled systems with two time scales are mainly for the cases with only one slow variable, in this paper we investigate the dynamical evolution of the Chen system with the controller described by Duffing oscillator on a slow time scale, which implies two slow variables may be involved in the coupled vector field. Different types of bursting oscillations such as the symmetric fold/fold bursting, symmetric fold/Hopf bursting, symmetric homoclinic/homoclinic bursting, and mechanism are presented, revealing that the mutual influence between the two slow variables may cause the bursting behaviors similar to those in the periodic excited systems.
Line spectrum chaotification of a double-layer vibration isolation floating raft system under multi-source excitation
Authors: Zhang Jing  , Xu Dao-Lin  , Li Ying-Li  , Zhou Jia-Xi  ,   College of Mechanical and Vehicle Engineering, Hunan University, State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body, Changsha 410082, China;,   College of Mechanical Engineering, Hunan Institute of Science and Technology, Yueyang 414006, China
Published: December 2020

The line spectrum characteristics of the radiated waterborne noises of an underwater vehicle can be reconstructed using the technique of chaotification, which can improve the acoustic stealth of the underwater vehicle. According to the particular application background, in this paper we study the chaotification issue with nonlinear time-delay feedback control for a double-layer vibration isolation floating raft system under multi-source excitation. From a simplified two-dimensional floating raft system model, a chaotification method with nonlinear time-delay feedback control is presented completely. It provides a standard procedure for line spectrum chaotification design. Numerical simulation results show the feasibility of this method. Under multi-source excitation, the effects of the control gain, time-delay and feedback frequency parameters on chaotification are investigated, and discussion is also extended to the case of the single-source excitation.
Stability of simulated wasted forms (Sr1-1.5xYx) TiO3 immobilizing 90Y
Authors: Mu Wan-Jun  , Xie Xiang  , Li Xing-Liang  , Yu Qian-Hong  , Zhang Rui  , Lü Kai  , Tang Hui  , Zhou Guan-Hong  , Wei Hong-Yuan  ,   Institute of Nuclear Chemistry and Physics, China Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

In order to study the stability of perovskite-type SrTiO3 used for immobilizing Y3+, Sr (NO3)2, TiO2 and Y2O3 are used as starting materials. The synthesized Y2O3-doped SrTiO3 can be generally represented as Sr1-1.5xYxTiO3 (0≤ x≤0.12) with the high temperature solid reaction. The phases, structures and microcosmic shapes of synthetic condensates are characterized by the X-ray diffraction, Raman and scanning electron microscopy, and long-term chemical stability is studied at 90 ℃. The results indicate that the phases of compounds change from perovskite to pyrocholre phase when the value of x is more than 0.08. The leaching rates of Sr2+ and Y3+ in waste form increase with the increase of immersion time. The highest leaching concentrations of Sr2+ and Y3+ for 42-day immersion are no more than 0.004 and 0.02 μg·mL-1, respectively.
Three-dimensional particle in cell simulation of multi-mode ion thruster optics system
Authors: Chen Mao-Lin  , Xia Guang-Qing  , Mao Gen-Wang  ,   Science and Technology on Combustion, Internal Flow and Thermo-Structure Laboratory, Northwestern Polytechnical University, Xi'an 710072, China;,   State Key Laboratory of Structural Analysis for Industrial Equipment, Dalian University of Technology, Dalian 116024, China
Published: December 2020

The optics is one of the main components of an ion thrust, which influences the performance and thruster lifetime. The operation of ion thruster can be evaluated by numerical simulation based on the current-voltage entrance condition, especially for thruster with a variety of operating modes. The plasma transport process is simulated with 3D-PIC (particle in cell) method for a two-grids optic. The performances of the NSTAR thruster under different operating modes are calculated and compared with the results of in-orbit test, verifying the correctness of the simulation mode. The influences of operation modes on the electric field distribution and the beam state are analyzed, and the requirements of multi-mode design for ion thruster are discussed. The results show that a convex sheath and concave zero equipotential surface away from the optic, low value of “saddle point”, and gentle downstream potential distribution, which help to improve ion pass rate, suppress electronic reflux and reduce Pits-and-Grooves corrosion, are the target of ion thruster mode design. Increasing beam voltage will result in a high loss caused by the divergence angle, and extend the beam current range for a good operation condition. For a large beam current mode, high beam voltage will make the beam have a better “focus” state, and reduce the Barrel corrosion. The results will provide a reference for the operation mode design for the multi-mode ion thruster.
A novel eigenvalue method for calculating the band structure of lossy and dispersive photonic crystals
Authors: Wang Hui  , Sha Wei E. I.  , Huang Zhi-Xiang  , Wu Xian-Liang  , Shen Jing  ,   School of Electronic and Information Engineering, Hefei Normal University, Hefei 230061, China;,   Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, China;,   Key Laboratory of Intelligent Computing and Signal Processing, Ministry of Education, Anhui University, Hefei 230039, China
Published: December 2020

A novel eigenvalue method is proposed to calculate the band structure of lossy and dispersive photonic crystal (PC). Using an idea from quantum transport problem, a standard linear eigenvalue equation rather than a nonlinear eigenvalue equation is obtained by a rigorous and artful transformation. And the physical parameters of lossy and dispersive PC are obtained by solving the linear eigenvalue equation using finite-difference frequency-domain (FDFD) method. Compared with other methods, the proposed method has great features, such as clear concept, simple calculation, less computing time and storage. A dielectric PC is simulated by the proposed method, and the results accord well with those from the traditional FDFD method, which verifies the validity of the proposed method. Moreover, the dispersion relation of the lossy and dispersive PC is calculated by the proposed method, and the surface plasmon frequency is obtained. Furthermore, the influence of loss on the dispersion relation and eigenmode field distribution is studied. The results provide some theoretical guidance for studying the lossy and dispersive PC.
Noise suppression for Lamb wave signals by Tsallis mode and fractional-order differential
Authors: Chen Xiao  , Wang Chen-Long  ,   Jiangsu Key Laboratory of Meteorological observation and Information Processing, Nanjing University of Information Science and Technology, Nanjing 210044, China;,   School of Electronic and Information Engineering, Nanjing University of Information Science and Technology, Nanjing 210044, China
Published: December 2020

To suppress the noise and increase the accuracy of feature extraction for ultrasonic Lamb wave signals, we present a new method based on the Tsallis mode and the fractional-order differential in this paper. Firstly, the fractional-order differentials of the amplitude spectrum of the noisy Lamb signal at different orders are obtained by using the fractional differential theory. Then, the cubic polynomial between the peak amplitude and the derivative order, and that between the peak frequency and the derivative order are proposed based on the Tsallis mode. The characteristic parameters of the amplitude spectrum are extracted with the developed equations. Finally, the Lamb signal without the noise is restored by combining the amplitude spectrum with the phase spectrum. Simulated and experimental results show that the proposed method can improve the performance parameters such as mean square error, r, and signal-to-noise ratio. Consequently, the new method based on the Tsallis mode and the fractional-order differential has the effective noise suppression performance for Lamb wave signals.