bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of crystallographic orientation on dendrite growth in directional solidification
Authors: Wang Xian-Bin  , Lin Xin  , Wang Li-Lin  , Bai Bei-Bei  , Wang Meng  , Huang Wei-Dong  ,   State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072, China
Published: December 2020

Dendrite is a typical pattern in directional solidification, attracting many theoretical and experimental researches. However, the effect of crystallographic orientation on dendrite growth is less considered in these researches. In this paper, using a transparent model alloy SCN-1.0 wt% Eth, the effects of crystallographic orientation on the incubation time of planar interface instability, the dendritical morphological feature, and the primary dendrite spacing in directional solidification are investigated. Three crystal grains with different angles between the dendrite axis direction and thermal gradient direction are chosen in our experimental. The experimental results show that the incubation time of planar interface instability increases with the deviation of dendrite axis from thermal gradient direction, which suggests that the deviation of dendrite axis favors the planar interface stability. And with the increase of deviation angle of dendrite axis, the side branches of dendrite become more asymmetric and the preferred side-branches suppress neighboring dendrite growth. Also it is found that the primary dendrite spacing becomes larger as the angle between the dendrite axis direction and thermal gradient direction increases.
Drain-induced barrier-lowering effect in surrounding-gate schottky barrier metal-oxide semiconductor field transistor
Authors: Xu Li-Jun  , Zhang He-Ming  ,   Key Laboratory for Wide Band-Gap Semiconductor Materials and Devices, School of Microelectronics, Xidian University, Xi’an 710071, China
Published: December 2020

Based on surrounding-gate schottky barrier metal-oxide semiconductor field transistor (MOSFET) structure, the distribution of surface potential is obtained by solving two-dimensional Poisson equation in cylindrical coordinates, and the threshold voltage model of surrounding-gate schottky barrier NMOSFET which is applicable to the low voltage of drain is built. According to the calculation results, the dependences of threshold voltage and drain-induced barrier-lowering on voltage of drain, channel radius and channel length are studied in detail, which can provide some reference for the design of surrounding-gate schottky barrier MOSFET device and circuit.
Preparation and photoluminescence of LiSrBO3:Eu3+ red-emitting phosphors for white leds
Authors: Liu Hong-Li  , Hao Yu-Ying  , Xu Bing-She  ,   Research Center of Advanced Materials Science and Technology, Taiyuan University of Technology, Taiyuan 030024, China;,   Department of Physics and Optoelectronics, Taiyuan University of Technology, Taiyuan 030024, China
Published: December 2020

LiSrBO3:xEu3+ phosphors were synthesized by conventional solid-state reaction and were systematically characterized by powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and photoluminescence spectroscopy. The excitation and emission spectra reveal that the LiSrBO3:Eu3+ phosphor can be effectively excited by ultraviolet (395 nm) and blue (466 nm) light and exhibits a satisfactory red performance which peaked at around 612 nm corresponding to the 5D0 → 7F2 transitions of Eu3+. The concentration quenching mechanism was verified to be a dipole–dipole interaction. The dopant R+ (R+ = Li+, Na+ and K+) as charge compensator can further enhance luminescence intensity, and the emission intensity of the phosphor doped Li+ is higher than that doped with Na+ or K+. Introduction of Al3+ reduced the symmetry of the crystal field and increased the emission of 612 nm (5D0 → 7F2), which improved the chromaticity coordinates of LiSrBO3: Eu3+ phosphor.
Effect of weight distribution on the synchronization of weighted generalized local-world networks
Authors: Dai Cun-Li  , Wu Wei  , Zhao Yan-Yan  , Yao Xue-Xia  , Zhao Zhi-Gang  ,   College of Engineering, Nanjing Agricultural University, Nanjing 210031, China
Published: December 2020

Weighted networks can give the detailed description of interaction between the agents of complex systems, so weighted networks is more resemble real-networks than unweighted networks. It is a new way to improve the properties of complex networks by adjusting the weight distribution. Based on the synchronization of unweighted complex networks, the synchronizability of weighted generalized local-world networks can be measured by eigenratio R. We find that weight distribution has an important effect on the synchronization of weighted generalized local-world networks. The uniform weight distribution will lead to better synchronizability.
A convolution algorithm of differential coefficients of liquid water based on vibrational Raman scattering
Authors: Han Dong  , Chen Liang-Fu  , Li Shen-Shen  , Tao Jin-Hua  , Su Lin  , Zou Ming-Min  , Fan Meng  ,   Normal College of Qingdao University, Qingdao 266071, China;,   State Key Laboratory of Remote Sensing Science, Jointly Sponsored by the Institute of Remote Sensing Applications of Chinese Academy of Sciences and Beijing Normal University, Beijing 100101, China;,   University of Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

Inelastic vibrational Raman scattering by liquid water is one significant limitation to the accuracy of the retrieval of trace gas constituents in atmosphere over waters, particularly over clear ocean waters, while using satellite data with differential optical absorption spectroscopy technique (DOAS). The effect which is similar to the Ring effect in atmosphere results in the filling-in of Fraunhofer lines, which is known as solar absorption lines. The inelastic component of the liquid water scattering causes a net increase of radiance in the line because more radiations shift to the wavelength of an absorption line than from this wavelength to other wavelengths. The solar spectrum transmitting atmosphere is convolved with vibrational Raman scattering coefficient of liquid water, divided by the original computed spectrum, with a cubic polynomial subtracted off, to create differential water Ring spectrum. This method is suggested in order to obtain an effective differential water Ring coeffient for the DOAS fitting process, which could be used to improve the accuracy of the retrieval of the trace gases concentration. The method does not rely on radiative transfer model of water, which would be time-consuming and depending on lot of parameters. Therefore, it is very fast and convenient.
Dynamics of rumor spreading in mobile social networks
Authors: Wang Hui  , Han Jiang-Hong  , Deng Lin  , Cheng Ke-Qing  ,   School of Computer and Information, Hefei University of Technology, Hefie 230009, China;,   Information and Network Centre, Hefei University of Technology, Heifei 230009, China
Published: December 2020

In this paper, we propose an improved CSR model for rumor spreading in mobile social networks. The dynamic equation of rumor spreading is modified to be suitable for user's habit in mobile social networks. In the acceptant probability model, negative and positive social reinforcements are considered. Furthermore, the people's accepting threshold for rumor accepting is taken into account. Analytically, a mean field theory is worked out by considering the influence of network topological structure as homogeneous. Under certain conditions, rumor spreads faster and wider in the new model than CSR rumor spreading model in homogeneous networks. Meanwhile, the multi-agent simulation results indicate that the information spreading process is sensitively dependent on initial conditions.
Hardware implementation for blind demodulation method for chaotic direct sequence spreadspectrum signals
Authors: Guo Jing-Bo  , Xu Xin-Zhi  , Shi Qi-Hang  , Hu Tie-Hua  ,   State Key Lab, Department of Electrical Engineering, Tsinghua University, Beijing 100084, China;,   Department of Electrical and Computer Engineering, University of Connecticut, USA;,   China Academy of Machinery Science & Technology, Beijing 100044, China
Published: December 2020

In this paper, we design a field-programmable gate array (FPGA)-based hardware implementation for blind demodulation method for chaotic direct sequence spread spectrum (CD3S) signals. Both transmitter and receiver are designed. The transmitter can produce ten chaotic maps as the spreading sequence. In the receiver, the mathematic model of unscented Kalman filter (UKF) chaotic fitting is built and simplified for hardware implementation. The hardware structure of the receiver is based on this simplified model. For real time fitting different chaotic maps, a dynamic adjustment strategy of range-differentiating factor is proposed. The additove white Gausian noise (AWGN) and multipath channel experiments verify the anti-noise and anti-multipath performance of the UKF chaotic fitting method on one hand. On the other hand, the experiments verify the method can demodulate CD3S signals spread by all ten chaotic maps effectively.
Design of an evanescent-coupled GeSi electro-absorption modulator based on Franz-Keldysh effect
Authors: Li Ya-Ming  , Liu Zhi  , Xue Chun-Lai  , Li Chuan-Bo  , Cheng Bu-Wen  , Wang Qi-Ming  ,   Institute State Key Laboratory on Integrated Optoelectronics, institute of Semiconductor, Chinese Academy of Sciences, Beijing 100083, China
Published: December 2020

We present a novel GeSi electro-absorption (EA) modulator design on a silicon-on-insulator platform. The GeSi EA modulator is constructed based on the Franz-Keldysh (FK) effect. The light is evanescent-coupled into the GeSi absorption layer from the rib Si waveguide. A contnet of 1.19% Si in SiGe absorption layer is chosen for C (1528–1560 nm) band operation. Simulation shows a high (3 dB) bandwidth of ～ 64 GHz and extinction ratio of 8.8 dB. Especially the insertion loss is as low as 2.7 dB.
A combined scheme of polarization mode dispersion compensation and polarization de-multiplexing in a polarization division multiplexing system with direct detection
Authors: Lin Jia-Chuan  , Xi Li-Xia  , Zhang Xia  , Tian Feng  , Liang Xiao-Chen  , Zhang Xiao-Guang  ,   State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876, China;,   The Key Laboratory of Optical Communications Science & Technology in Shandong Province, Liaocheng University, Liaocheng 252000, China
Published: December 2020

A model of polarization mode dispersion (PMD) and state of polarization (SOP) variation induced coherent crosstalk is established in a polarization division multiplexing system. The properties of radio frequency power of one channel in the presence of PMD are investigated. A combined scheme of PMD compensation and polarization de-multiplexing in optical domain is proposed, which is based on monitoring of the feedback signal of RF power. A modified particle swarm optimization algorithm is also used for the adaptive polarization control. The validity of the PMD compensation and polarization de-multiplexing scheme proposed here is demonstrated in a 112Gb/s-PDM-DQPSK simulation system. Results show that the PMD tolerance of the transmission system is increased by 20 ps with 1 dB OSNR margin and the channel separation is accomplished as well.
First-principles study on elastic properties of hexagonal phase ErAx (A=H, He)
Authors: Fan Kai-Min  , Yang Li  , Sun Qing-Qiang  , Dai Yun-Ya  , Peng Shu-Ming  , Long Xing-Gui  , Zhou Xiao-Song  , Zu Xiao-Tao  ,   School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054, China;,   Department of Physics and Engineering Technology, Sichuan University of Arts and Science, Dazhou 635000, China;,   School of Science of Huaihai Institute of Technology, Lianyungang 222005, China;,   Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

The elastic properties of hexagonal phase ErAx (A=H, He) have been calculated by the first-principles method, where x=0, 0.0313, 0.125, 0.25. Effects of different concentrations of hydrogen and helium on the elastic properties of ErAx systems have been investigated in detail. Results show that the elastic constants, Young's modulus, bulk modulus and shear modulus of ErHx systems increase mainly with increasing hydrogen concentration, whereas, those elastic properties of ErHex systems almost decrease with increasing helium concentration. We have investigated the changes in the charge densities of Er atoms produced by A atoms. It was found that the mechanism for the change of the elastic properties of hexagonal phase ErHx with increasing hydrogen atoms is different from that of ErHex with increasing helium atoms.
Effects of parameter modifications on phase transition properties of ferroelectric thin films
Authors: Lu Zhao-Xin  ,   College of Mechanical Engineering, Linyi University, Linyi 276005, China
Published: December 2020

Within the framework of effective-field theory with correlations, phase transition properties of ferroelectric thin films with different symmetrical surfaces described by the spin-1/2 transverse field Ising model are studied systematically by the differential operator technique. According to the coupling equations with the layer polarization average, the analytical general equations for phase diagrams of multiple-surface ferroelectric thin films with different surface layers have been derived. Then, effects of various parameter modifications on the crossover values from the FPD (ferroelectric-dominant phase diagram) to the PPD (paraelectric-dominant phase diagram) and phase transition regions in the parameter space are discussed in detail. In comparison with the mean-field approximation, the results indicate that the effective-field theory with correlations maybe reduce the ferroelectricity of the ferroelectric thin films more exaggeratedly than the mean-field approximation to some extent.
Calculation and analysis of surface acoustic wave properties of ZnO film on diamond under different excitation conditions
Authors: Qian Li-Rong  , Yang Bao-He  ,   School of Precision Instrument and Opto-electronics Engineering, Tianjin University, Tianjin 300072, China;,   School of Electronic Information Engineering, Tianjin University of Technology, Tianjin Key Laboratory of Film Electronic and Communication Devices, Tianjin 300384, China
Published: December 2020

In the last twenty years, the ZnO/diamond layered structure for surface acoustic wave (SAW) devices have been widely studied and have attracted great attention, due to its advantages of high acoustic velocity, high electromechanical coupling coefficient and high power durability. Distinguished from the conventional single-crystal substrate (such as quartz, lithium niobate), ZnO/diamond layered structure shows dispersive SAW properties, which can be excited by four ways: interdigital transducer (IDT)/ZnO/diamond, IDT/ZnO/shorting metal/diamond, ZnO/IDT/diamond, and shorting metal/ ZnO/IDT/diamond. In this paper, the formulation based on the stiffness matrix method for calculating the effective permittivity of ZnO/diamond layered structure under four excitation conditions is given first. Then, by using this formulation, the SAW properties of the monocrystalline ZnO (002) film on polycrystalline diamond and the polycrystalline ZnO (002) film on polycrystalline diamond are calculated respectively. Based on the results of calculation, the ZnO film thicknesses qualified to design and fabricate SAW device are analyzed in detail. Finally, we discuss the function of diamond film thickness of ZnO/diamond/Si layered structure so as to avoid the influence of the silicon substrate on the SAW properties.
Effects of sefl-reduction of glass matrix on the broadband near infrared emissions from Bi-doped alkali earth aluminoborosilicate glasses
Authors: Li Yong-Jin  , Song Zhi-Guo  , Li Chen  , Wan Rong-Hua  , Qiu Jian-Bei  , Yang Zheng-Wen  , Yin Zhao-Yi  , Wang Xue  , Wang Qi  , Zhou Da-Cheng  , Yang Yong  ,   School of Materials Science and Engineering, Kunming University of Science and Technology, Kunming 650093, China;,   Key Lab of Advanced Materials in Rare & Precious and nonferrous Metals, Ministry of Education, Kunming University of Science and Technology, Kunming 650093, China
Published: December 2020

We report the effects of self-reduction of glass matrix on the broadband near infrared (NIR) emissions from Bi-doped alkali earth aluminoborosilicate glasses. Bi2O3 -doped as well as Eu2O3, -doped as a comparison, 35SiO2-25AlPO4-12.5Al2O3-12.5B2O3-15RO (R=Ca,Sr,Ba) glasses were prepared in air. Results show that the self-reduction process of Eu3+→Eu2+ occurs in this glass matrix. Meanwhile the intensity of NIR emission peaked at about 1300nm increases with the increase in the radius of alkali earth ions, while the intensity of both NIR emission peaked at about 1100nm and the red emission from Bi2+decreases. Then the origins of infrared-emitting bismuth centers were discussed according to the correlation of the conversion of Bi ions with the size of alkali earth ions. The results of this work is helpful for understanding the nature of Bi-NIR-emission and may be a guide for the selection of composition of high performance Bi-doped glass.
Study on the photoluminescence properties of InN films
Authors: Wang Jian  , Xie Zi-Li  , Zhang Rong  , Zhang Yun  , Liu Bin  , Chen Peng  , Han Ping  ,   Jiangsu Provincial Key Laboratory of Photonic and Electronic Materials Science and Technology, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, China
Published: December 2020

The photoluminescence (PL) properties of InN films grown by metal organic chemical vapor deposition (MOCVD) have been investigated. InN has a high level of background carrier concentration, which makes the Fermi level lie above the conduction band. By nonlinear fitting of the PL results, along with the energy band relations, we calculated the band gap of InN film to be 0.67 eV and the carrier concentration n=5.4×1018 cm-3. Thus we found a connection between PL results and the carrier concentration of InN films. In addition, we also studied the dependence of peak position and intensity of PL on temperature: the intensity of photoluminescence decreases as the temperature increases, and the peak position shows a red shift instead of an S-shape variation. Such a difference may be explained by a huge full width at half maximum of PL spectra. Also the concentration of carriers and the magnitude of the built-in electric field in the material may have influence on such a result.
Spectroscopic properties and energy transfer of Ce3+/Eu2+ codoped oxide glasses with high Gd2O3 concentration
Authors: Shen Ying-Long  , Tang Chun-Mei  , Sheng Qiu-Chun  , Liu Shuang  , Li Wen-Tao  , Wang Long-Fei  , Chen Dan-Ping  ,   R&D Center of High Power Laser Components, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China;,   Graduate School of the Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

Eu2+/Ce3+ single doped and co-doped oxide glasses with high Gd2O3 concentration were prepared in a reducing atmosphere using a high-temperature glass melting method. Excitation and emission spectra measurements indicated that Ce3+ can enhance the luminescence intensity of Eu2+ effectively, which exhibited a 2.3 times increasa. The difference between the luminescence lifetimes of Eu2+ with and without Ce3+ doping indicated that the energy transfer efficiency could reach 61.5%, for which the energy transfer mechanism was investigated further. These researches suggest that co-doping method can significantly improve the luminescence capabilities of Eu3+ in the oxide glasses with high Gd2O3 concentration.
Anti-synchronizing different chaotic systems using active disturbance rejection controller based on the chaos particle swarm optimization algorithm
Authors: Liu Fu-Cai  , Jia Ya-Fei  , Ren Li-Na  ,   Key Laboratory of Industrial Computer Control Engineering of Hebei Province, Yanshan University, Qinhuangdao 066004, China
Published: December 2020

For a class of continuous time different structure chaotic systems, due to the strong robustness and adaptability of active disturbance rejection controller (ADRC), we put forward a kind of the anti-synchronization of different structure chaotic systems with auto-disturbance-rejection control strategy. Because there are many parameters in ADRC and they are very difficult to set, in this paper we propose a chaotic particle swarm optimization algorithm to optimize the parameters of controller. Using Lorenz system and Chua system with different structures as an example to perform the simulation test, the results of the simulation verify that the proposed method can realize the anti-synchronization control of the different structure chaos systems faster and has a very strong anti-interference ability.
Investigation on the thermal and electrical conductivity of water based zinc oxide nanofluids
Authors: Li Yi-Tong  , Shen Liang-Ping  , Wang Hao  , Wang Han-Bin  ,   Faculty of Physics and Electronic Technology, Hubei University, Wuhan 430062, China
Published: December 2020

Spherical ZnO nanoparticles each with a uniform size are synthesized by a hydrothermal method. These ZnO nanoparticles are then dispersed into water by ultrasonic vibrating to form stable nanofluids. The electrical conductivity of water-based ZnO nanofluids with a variety of temperature and volumetric fractions are investigated. The volumetric-fraction-dependent thermal conductivity is also measured at room temperature. Experiments indicate that the electrical conductivity of ZnO nanofluid reveals a non-linear relationship versus volumetric fraction. However, it presents a quasi linear relationship versus temperature. The thermal conductivity is enhanced nearly linearly with volumetric fraction increasing. Moreover, a modified model is established based on Maxwell thermal conductivity model and Brownian dynamics theory by considering boundary adsorption layer, aggregation and Brownian motion of nanoparticles in the fluid. The expected thermal conductivity values based on the modified model are in good agreement with our experimental data, suggesting that our modified model might be more accurately adapted to the nanofluids thermal conductivity.
Effects of pulse transverse profile on electron bow-wave injection of electrons in laser wakefield acceleration
Authors: Zhang Guo-Bo  , Ma Yan-Yun  , Zou De-Bin  , Zhuo Hong-Bin  , Shao Fu-Qiu  , Yang Xiao-Hu  , Ge Zhe-Yi  , Yu Tong-Pu  , Tian Cheng-Lin  , Ouyang Jian-Ming  , Zhao Na  ,   College of Science, National University of Defense Technology, Changsha 410073, China
Published: December 2020

In this paper we study the effects of transverse profile of incident laser on trapping of electrons in an electron bow-wave injection regime. By using the particle-in-cell code, we find that the super-gaussian profile laser pulse can drive more energetic electrons of the electron bow-wave into the bubble with higher longitudinal injection velocity. At last, the total number of trapped electrons increases almost 5 times. And the quality of electron beam is also improved obviously.
The damage effect and mechanism of the bipolar transistor induced by different types of high power microwaves
Authors: Ma Zhen-Yang  , Chai Chang-Chun  , Ren Xing-Rong  , Yang Yin-Tang  , Qiao Li-Ping  , Shi Chun-Lei  ,   Key Laboratory of Ministry of Education for Wide Band-Gap, Semiconductor Materials and Devices, School of Microelectronics, Xidian University, Xi’an 710071 China
Published: December 2020

By analyzing the variations of the internal distributions of the temperature with time and the current density and the burnout time with the signal amplitude, we study the internal damage process and mechanism of the typical silicon-based n+-p-n-n+ structure bipolar transistor induced by three kinds of high power microwaves such as triangular wave, sinusoidal wave and square wave. The results show that the base-emitter junction is the damage position and the device is more susceptible to damage under the injection of the square waves. The displacement current and the burnout time increase but the proportion of the displacement current in the total current decreases with signal amplitude increasing. The injected power plays a determinative role in the damage process compared with the displacement current. Adopting the data analysis software, the relation equation between the burnout time t and the signal frequency f is obtained. It is demonstrated that the burnout time increases with signal frequency increasing, and the equations of the three kinds of high power microwaves all agree with the formula t= afb.
OFDMA adaptive resource allocation based on fish swarm algorithm
Authors: Wang Zhao  , Li You-Ming  , Cheng Bin  , Zou Ting  ,   Institute of Communication Technology, Ningbo University, Ningbo 315211, China
Published: December 2020

An adaptive resource allocation algorithm is proposed for the adaptive resource allocation problem of orthogonal frequency division multiple access, in which a novel subcarrier and power allocation algorithms based on fish swarm algorithm are proposed. Subcarrier allocation is first implemented on condition that the m total power is distributed uniformly on each subcarrier. The fish swarm algorithm is then used to fulfill power allocation through the global search ,including a fitness function of the user's fairness and system capacity. Computer simulation results show that the proposed algorithm not only guarantees user fairness but also achieves maximal system capacity.
Research of X-ray pulsar navigation simulation source
Authors: Sheng Li-Zhi  , Zhao Bao-Sheng  , Wu Jian-Jun  , Zhou Feng  , Song Juan  , Liu Yong-An  , Shen Jing-Shi  , Yan Qiu-Rong  , Deng Ning-Qin  , Hu Hui-Jun  ,   State Key Laboratory of Transient Optics and Photonics, Xi’an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi’an 710119, China;,   University of Chinese Academy of Sciences, Beijing 100039, China;,   Wuxi Institute of Commerce, Wuxi 214153, China;,   Shandong Aerospace Electro-Technology Institute, Yantai 264670, China
Published: December 2020

As an autonomous navigation method, X-ray pulsar navigation can provide position, timing and attitude information for various spacecrafts. Since the X-rays (1-20 keV) from the pulsar can not penetrate the earth atmosphere, an X-ray source in laboratory needs to be set up to test and calibrate the detector. In this paper an arbitrary X-ray pulse source to simulate the neutron pulsar signal is proposed. The main components of the simulation source are a grid controlled X-ray tube and arbitrary pulse generation electronics. With the arbitrary pulse voltage applied to the tube grid, the X-ray intensity is controlled. Through electron optics design, the tube electrode parameters are optimized. A grid controlled X-ray tube is fabricated and tested. Using a micro-channel plate detector to detect and reconstruct the generated X-ray pulses, the similarity between the accumulated profile and the original pulsar profile is better than 95%. The frequency stability of the pulsar source emulator is about 2×10-11.
Stability and bifurcation of epidemic spreading on adaptive network
Authors: Lu Yan-Ling  , Jiang Guo-Ping  , Song Yu-Rong  ,   College of Computer, Nanjing University of Posts and Telecommunications, Nanjing 210004, China;,   College of Automation, Nanjing University of Posts and Telecommunications, Nanjing 210004, China
Published: December 2020

Adaptive network is characterized by feedback loop between states of nodes and topology of the network. In this paper, for adaptive epidemic spreading model, epidemic spreading dynamics is studied by using a nonlinear differential dynamic system. The local stability and bifurcation behavior of the equilibrium in this network model are investigated and all kinds of bifurcation point formula are obtained by analyzing its corresponding characteristic equation of Jacobian matrix of the nonlinear system. It is shown that, when the epidemic threshold is less than epidemic persistence threshold R00c, the disease always dies out and the disease-free equilibrium is asymptotically locally stable. If R0c01, a backward bifurcation leading to bistability possibly occurs, and there are possibly three equilibria: a stable disease-free equilibrium, a larger stable endemic equilibrium, and a smaller unstable endemic equilibrium. If R01, the disease is uniformly persistent and only one endemic equilibrium is asymptotically locally stable. It is also found that the system has saddle-node bifurcation, transcritical bifurcation, and Hopf bifurcation. Numerical simulations are given to verify the results of theoretical analysis.
The model design and performance analysis of quantum signaling switch
Authors: Zhu Wei  , Nie Min  ,   College of Communication and Information Engineering, Xi'an university of posts and telecommunications, Xi'an 710061, China
Published: December 2020

This paper puts forward a quantum signaling switch model. The quantum signaling switch consists of a classical information control module, an exchange control module and a quantum exchange module. Classical control module transmits the initial entangled state information to the entanglement measurement and switching unit and updates the routing information. Exchange control module will choose the path, and is ready for the distribution channel of the entanglement photons. The quantum exchange module generates quantum entanglement pairs, measures the Bell state and achieves entanglement swapping. Quantum signaling switches can realize multi-user communication and local area network communication. Through the performance analysis and simulation of the switch, the results show that the switch is simple in structure, secure and easy to expand; also the time delay is small. This will be helpful for the construction of the quantum communication network.
Study on partial discharge signal detection by coupled Duffing oscillators
Authors: Wu Yong-Feng  , Huang Shao-Ping  , Jin Guo-Bin  ,   College of Electrical & Information Engineering, Hunan Institute of Engineering, Xiangtang 411104, China
Published: December 2020

Bidirectional ring-coupled Duffing oscillator hasbeen investigated. A phenomenon is discovered, showing that when one of the oscillators is driven by pulsed signal under certain parameter conditions, this and the other oscillators will suddenly change from synchronization to transient non-synchronization and then rapidly return to synchronization, which is defined as transient synchronization mutation in this paper. This phenomenon is used to accurately detect partial discharge signal in strong noise environments. The experimental tests show that this method achieves good detection effect in low SNR for partial discharge signal of different discharge electrode, which can further extend the weak signal detection range based on Duffing oscillator.
Temperature-insensitive magnetic-field measurement using all-fiber Sagnac interferometers
Authors: Wen Feng  , Wu Bao-Jian  , Li Zhi  , Li Shu-Biao  ,   Key Laboratory of Optical Fiber Sensing and Communications of the Ministry of Education, University of Electronic Science and Technology of China, Chengdu 611731, China
Published: December 2020

Magnetic field and temperature dependence of Sagnac interferometers consisting of birefringent magneto-optic fibers is investigated. Experimental results show that the transmission spectrum of the all-fiber Sagnac interferometer moves towards the shorter wavelength side with the increase in temperature (temperature coefficient -0.435 nm/℃), and the transmissivity becomes wavelength- insensitive for a larger magnetic induction. And then, the temperature-insensitive magnetic field measurement is achieved by adjusting the polarization controller within the interferometer, and the magnetic field coefficient is 189 mW/T2 in the experiment, which is in agreement with the theoretical results.
Measurement of atmospheric CO2 vertical column density using weighting function modified differential optical absorption spectroscopy
Authors: Sun You-Wen  , Xie Pin-Hua  , Xu Jin  , Zhou Hai-Jin  , Liu Cheng  , Wang Yang  , Liu Wen-Qing  , Si Fu-Qi  , Zeng Yi  ,   Key Lab of Environmental Optics & Technology, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China;,   Harvard-Smithsonian Center for Astrophysics, Harvard University, Cambridge, MA, USA
Published: December 2020

In this paper, we demonstrate a method of atmospheric CO2 vertical column density (VCD) retrieval by using weighting function modified differential optical absorption spectroscopy (WFM-DOAS). Direct sun measurement serves as an example for WFM-DOAS fitting. The atmosphere is divided into 50 layers in the process of WFM-DOAS retrieval, while the simulated sun-normalized radiance and the total weighting functions (CO2, H2O and CH4) for each measurement are computed in terms of the radiative transfer model (RTM) SCIATRAN by using the HITRAN data base and the solar spectrum from Livingston and Wallace (1991). The CO2 vertical column density time series were obtained by utilizing WFM-DOAS fitting method to all direct sun measurement spectra. Fitting errors are all less than 3%. Fitting results for two different DOAS algorithms are compared with each other. It is indicated that the WFM-DOAS technique has the potential of being applied in passive gas remote sensing in the infrared region.
Effects of high pressure annealing technique on the structure, morphology and electric properties of 0.65PMN-0.35PT thin films
Authors: Guo Hong-Li  , Yang Huan-Yin  , Tang Huan-Fang  , Hou Hai-Jun  , Zheng Yong-Lin  , Zhu Jian-Guo  ,   The Institute of Condensed Matter Physics, Yangtze Normal University, Chongqing 408100, China;,   School of Materials Engineering, Yancheng Institute of Technology, Jiangsu 224051, China;,   College of Materials Science and Engineering, Sichuan University, Chengdu 610064, China
Published: December 2020

Thin films of 0.65PMN-0.35PT PMN=Pb (Mg1/3Nb2/3)O3 and PT=PbTiO3 with a thickness about 250 nm were prepared on LaNiO3/SiO2/Si substrates by radio frequency magnetron sputtering. The films were annealed using high pressure annealing (HPA) technique in oxygen atmosphere. Effect of HPA on the crystal structure, morphology and electrical properties of the films was studied. XRD patterns of the films indicated that PMN-PT films treated by HPA in oxygen atmosphere (annealing temperature 400℃) showed a pure perovskite phase, with highly (100) preferred orientation. The strong and sharp diffraction peak showed the better crystallization of PMN-PT thin films after HPA. SEM observations showed that a rod or bubble morphology was present on the films surface. Ferroelectric properties tests showed that the PMN-PT film annealed in oxygen atmosphere at a pressure of 4 MPa, and annealing time of 4 h had good ferroelectric properties, in which the remanent polarization (Pr) could reach 10.544 uC/cm2. The shape of electric hysteresis was better, but the leakage current was too large, which may be due to the microstructure of the films. Meanwhile, the dielectric tests indicated that PMN-PT thin films could show very good dielectric properties, and the dielectric constant (r) could reach 913, and dielectric loss (tg) was very small, only 0.065.
Experimental study on polarization-independent reflector structure based on magneto-optical crystal and two mirrors
Authors: Zhao Gu-Hao  , Zhao Shang-Hong  , Yao Zhou-Shi  , Hao Chen-Lu  , Meng Wen  , Wang Xiang  , Zhu Zhi-Hang  , Liu Feng  ,   School of Information and Navigation, Air Force Engineering University, Xi'an 710077, China;,   Xi'an Branch of China Academy of Space Technology, Xi'an 710000, China;,   School of Air and Missile Defense, Air Force Engineering University, Xi'an 710077, China
Published: December 2020

The experimental demonstration of polarization-independent reflection structure that consists of two magneto-optical crystals and two mirrors is reported. According to the characteristics of polarization compensation, the reflection structure was simplified in this paper. A single magneto-optical crystal and two mirrors reflection structure is presented to simplify the polarization-independent reflection structure. The experiment shows that the degrees of polarization maintenance of the two reflection structures are both higher than 99.97%. By way of contrast, the polarization states of 90° reflection laser of single mirror and two mirrors are measured. Under these conditions, the degrees of polarization maintenance of mirrors are 92.1% and 76.2%, respectively.
Tunable two-dimensional photonic crystal cavity all-optical switching infiltrated with liquid-crystal
Authors: Zhou Jian-Wei  , Liang Jing-Qiu  , Liang Zhong-Zhu  , Tian Chao  , Qin Yu-Xin  , Wang Wei-Biao  ,   State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China;,   Graduate School of the Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

A novel photonic crystal (PC) all-optical switch based on the shift of defect mode is demonstrated. Two photonic crystal waveguides are connected by a photonic crystal cavity. The point defect of the photonic crystal cavity is filled with phenylacetylene liquid cyrstals intermingled with azobenzene. The output of the optical switch is controlled by adjusting the rotation angle of the liquid crystals' orientation vector. And the optical switch is numerically investigated by using the finite difference time domain (FDTD) method and plane wave expansion method. Numerical simulation shows that the optical switch based on the PC cavity can be changed by adjusting the applied linearly polarized light. Results show that the switch has low threshold power density, great extinction ratio, and small size.
Non-imaging secondary (NIS) for axial symmetrical two-stage optical concentrator
Authors: Chen Ying-Tian  , He Zuo-Xiu  ,   Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing 100190, China;,   Beijing Sunco Ltd. Beijing 100085, China
Published: December 2020

Non-imaging reflector may present the advantage to eliminate the dark image in beam down 2-stage optical concentrator. The working principle of the non-imaging secondary (NIS) for an axial symmetric concentrator is revealed. The geometrical shape of NIS can generally be high order surface not restricted to the quadratic one in imaging optics or the CPC in non-imaging optics. The article has described the method to determine the parameters of the curve. To break the tradition in optics, we have demonstrated in the article that beside the quadratic curve, cubic curve can be equally used to form NIS. In the respect of solar energy application, we have made the discussion on the behavior of NIS for solar disc effect and how a new parameter can be used to optimize the design.
Experimental investigation of two-dimensional multi-point defect phononic crystals with square lattice
Authors: Zhao Huan-Yu  , He Cun-Fu  , Wu Bin  , Wang Yue-Sheng  ,   Institute of Engineering Mechanics, Beijing Jiaotong University, Beijing 100044, China;,   College of Mechanical Engineering and Applied Electronics Technology, Beijing University of Technology, Beijing 100124, China
Published: December 2020

The characteristics of multi-point defect phononic crystal (PC) composed of square array of circular steel cylinders in water are investigated experimentally using the ultrasonic immersion transmission technique. The band structures of the PCs are obtained by the finite element method with 9×9 supercell approximation. A very good agreement with the experimental results, numerical transmission data and eigenmode frequencies of band structures is observe. Meanwhile the number of multi-point defects affects the localized modes of cavities and propagation characteristics, and the eigenmodes of defects show the symmetric or antisymmetric modes in designing the new type of acoustic wave devices.
Low-frequency band gaps in phononic crystals with composite locally resonant structures
Authors: Zhang Si-Wen  , Wu Jiu-Hui  ,   School of Mechanical Engineering, Xi'an Jiaotong University, Xi'an 710049, China
Published: December 2020

In this paper, a novel locally resonant structure with composite units is proposed. Formation mechanisms and low-frequency characteristics of the band gaps in the proposed structure are investigated using finite element methods. Frequency positions of band gaps depend on natural frequencies of the corresponding locally resonant modes. And the gap width is related to both the Q factor of the locally resonant modes and the interaction strength in-between the locally resonant structural units. Phononic crystal structures with composite units exhibit multiple resonances and band gaps in low-frequency range, depending on the arrangement of locally resonant units. Due to the mode degeneracy of the vertical and horizontal local resonances, the composite structures possess band gaps below 200Hz with the total gap width more than 60% and the lowest frequency down to 18Hz. The structures and results provide a new effective method for phononic crystal structures to obtain broadband gaps in low-frequency range.
Study of plasmonic nanolaser based on the deep subwavelength scale
Authors: Huang Hong  , Zhao Qing  , Jiao Jiao  , Liang Gao-Feng  , Huang Xiao-Ping  ,   University of Electronic Science and Technology of China, Chengdu 610054, China
Published: December 2020

We have proposed a novel surface plasmonic nanolaser based on a nanowire/air gap/metal thin film hybrid structure to carry out theoretical research and simulation analysis. Opening an air groove in the MgF2 insulating layer, then making a nanowire embedded on the top of the air slot but maintaining a gap between the nanowire and the metal layer, thereby we produce a coupled hybrid plasmonic waveguide and a significant field enhancement effect. This structure enables the realization of an air gap. By simulating the modal properties and the lasing threshold of the hybrid plasmonic mode under different geometric parameters, the capacity of subwavelength scale with low propagation loss and high field confinement is demonstrated. Finally we achieve the nanolaser's optimal structure size. Compared with the general diffraction limit laser, this structure can reduce the physical size of the device and the physical mode. The proposed nanolaser could be easily integrated with various nanophotonic devices, and it may become an appealing candidate for future active plasmonic systems.
Crystallization behavior and thermal stability of Al-Ni-RE metallic glasses
Authors: Zhang Zhang  , Xiong Xian-Zhong  , Yi Jiao-Jiao  , Li Jin-Fu  ,   School of Materials Science and Engineering, State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200240, China
Published: December 2020

A series of Al-Ni-RE (RE=La, Ce, Y) amorphous ribbons were prepared. The crystallization behavior and primary phases were investigated using X-ray diffraction and differential scanning calorimeter, and their relationships with the alloy composition and atomic features were analyzed. Results show that if the topological instability parameter λ was modified using effective atomic radii, the metallic glasses in an Al-Ni-RE system can be classified into nanocrystalline, nanoglassy and glassy types according to their crystallization behaviors by two critical values of the modified topological instability parameter λ'. Linear relationships of onset temperature of crystallization and mixing enthalpy with λ' are also clearly revealed, indicating that λ' is closely related to the thermal stability of Al-Ni-RE metallic glasses.
Effect of magnetic field on growth of intermetallic compound layers in Fe-Fe50wt.%Si diffusion couple
Authors: Sun Zong-Qian  , Zhong Yun-Bo  , Fan Li-Jun  , Long Qiong  , Zheng Tian-Xiang  , Ren Wei-Li  , Lei Zuo-Sheng  , Wang Qiu-Liang  , Wang Hui  , Dai Yin-Ming  ,   Shanghai Key Laboratory of Modern Metallurgy & Material Processing, Shanghai University, Shanghai 200072, China;,   Key Laboratory of Applied Superconductivity, Chinese Academy of Sciences Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190, China
Published: December 2020

In this paper, Fe-Fe50 wt.%Si diffusion couples are subjected to 1200℃ heat treatment in static magnetic field. Fe-Fe50 wt.% Si diffusion couples were prepared by vacuum casting technology and later sectioned and polished for scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) studies before heat treated. Microstructures of the treated samples which were polished first were analyzed by SEM and EDS; results show that the phase components of the interfacial intermetallic compound layers are FeSi phase layer and Fe-Si solid solution layer whether the samples were treated with or without magnetic field, and the layer widths in the samples treated with magnetic field are smaller than those without magnetic field. According to the parabolic law, the interdiffusion coefficients of the interfacial intermetallic compound layers were calculated and the interdiffusion coefficients of FeSi phase and Fe-Si solution under a field of 0.8 T are reduced by 26.7% and 34.1%. The Gibbs energy due to applied field was calculated, data analysis shows that the reduction of interfacial intermetallic compound layer coefficients is attributed to the decrease of frequency factor, not the activation energy. Decrease in layer thickness decrease is suggested to be related to the retardation of atomic diffusion resulting from the magnetic field, and a possible theory based on Larmor precession is given to explain this effect.
Spatiotemporal evolution of the droughts and floods over China
Authors: Ye Min  , Qian Zhong-Hua  , Wu Yong-Ping  ,   College of Physical Science and Technology, Yangzhou University, Yangzhou 225002, China
Published: December 2020

Based on the global Palmer drought severity index (PDSI) data and monthly precipitation data from China, using linear trend analysis, comparative analysis and EOF methods, the spatiotemporal evolution of the droughts and floods over China during 1961–2010 has been analyzed. Results show that: The decadal spatial distribution of PDSI in spring is similar to that in year-round. The regional differences of PDSI in summer and autumn are obvious, especially in autumn. According to the linear analysis, climate in North China, Northeast China, Southwest China, South China and East China is becoming dry obviously; while the west of Northwest China is becoming wet. The PDSI in summer from 1961 to 2010 is also analyzed by experience orthogonal function (EOF). Results show that droughts and floods occur frequently in China since the 1980s and the intensity of droughts and floods is also increased, especially droughts in the North China, Southwest China, Northeast China and floods in East China.
Band gap design for one-dimensional periodic structure with three oscillators
Authors: Gao Ming  , Wu Zhi-Qiang  ,   Department of Mechanics, School of Mechanical Engineering, Tianjin University, Tianjin 300072, China;,   Department of Mechanics, School of Science, Shandong University of Science and Technology, Qingdao 266590, China
Published: December 2020

Dimensionless dispersion curve equation of one-dimensional periodic structure with three oscillators is deduced. It is proved by singularity theory that the topology of the dispersion curves does not change with mass and stiffness parameter. Then the equations of initial and final frequencies of the bands are presented. The method of band gap design is gained consequently. Two examples i.e., the system with the same stiffness and the system with the same mass, are given to verify it. The method may provide the reference for designing the band gap of the photonic and phononic crystals.