bluuebunny/crossref_metadata_2025 huggingface dataset:
Study on the self-heating effect in silicon-on-insulator devices with SOANN buried oxide
Authors: Cao Lei  , Liu Hong-Xia  ,   Key Lab of Ministry of Education for Wide Band-Gap Semiconductor Materials and Devices, School of Microelectronics, Xidian University, Xi'an 710071, China
Published: December 2020

In this paper, we present a new silicon-on-insulator (SOI) buried oxide structure, i.e., silicon on aluminum nitride with nothing (SOANN). In the novel structure, the traditional SiO2 is replaced by A1N, and gas cavity is constructed in the SOI buried oxide. The self-heating effect of novel SOI device is analyzed. The result shows that using A1N as a buried oxide, the temperature of lattice and the effectively restrained self-heating effect can decrease. In addition, the gas cavity in the buried oxide can provide a heat emission passage and reduce the dielectric constant. The coupling effect of electric field lines from drain to source is weakened, and the drain induced barrier lowering effects is effectively restrained. Therefore, this new SOANN structure can improve the performance of the SOI devices, and provide high reliability as well.
Laser-induced ultrafast spin transfer in linear magnetic molecular ions
Authors: Li Chun  , Zhang Shao-Bin  , Jin Wei  , Georgios Lefkidis  , Wolfgang Hübner  ,   School of Mechanics, Civil Engineering and Architecture, Northwestern Polytechnical University, Xi'an 710072, China;,   Department of Physics and Research Center OPTIMAS, Kaiserslautern University of Technology, 67653 Kaiserslautern, Germany
Published: December 2020

The demagnetization, spin switching, and spin transfer in magnetic molecular systems can be theoretically achieved via the laser-induced Λ process. In the present work, both quantum chemistry ab initio calculations and our self-written programs are adopted to investigate the spin-transfer behavior of the magnetic molecular ions with linear configuration. It is shown for the first time that the Λ process based ultrafast spin transfer can be achieved in a linear two-magnetic-center molecular ion [Fe-O-Co]+, and the fidelity of the population transfer exceeds 90%. The present theoretical prediction shows that the magnetocrystalline anisotropy of a molecular system can be enhanced by properly adjusting the direction of the applied magnetic field, which is shown to be a better way to improve the spin-transfer ability of the molecular system than by increasing additional bridging atoms since it could avoid the complexity of the latter situation in practical applications. At the same time, the present spin-transfer scenario indicates that the fidelity of the population transfer could also be evidently increased.
Ultrafast spectroscopy of the Mn3+ dd transition in YMnO3 film
Authors: Xu Yue  , Jin Zuan-Ming  , Li Gao-Fang  , Zhang Zheng-Bing  , Lin Xian  , Ma Guo-Hong  , Cheng Zhen-Xiang  ,   Department of Physics, Shanghai University, Shanghai 200444, China;,   Institute for Superconductor and Electronic Materials, University of Wollongong, North Wollongong, NSW 2500, Australia
Published: December 2020

Photoinduced carrier dynamic behavior of the Mn3+ 3d resonance excitation of YMnO3 thin film is studied by the femtosecond time resolved spectroscopy. The photon energy of the pump pulse is tuned to 1.70 eV, which is corresponding to the Mn3+ 3d energy level at room temperature. With resonant excitation, the transient transmission signals at the zero-delay time gradually increase with temperature increasing. The temperature dependent transmission change results from the blue shift of the Mn3+ 3d energy level, which is believed to originate from the short-range antiferromagnetic order in YMnO3 film. In addition, the fast and slow relaxations of the transient signal arise from electronic-phonon and phonon-spin interactions, respectively. When the temperature is lower than TN, the relaxation time of the fast process increases significantly, which indicates that the strength of electronic-phonon coupling is restrained by the long-range antiferromagnetic order.
Electronic properties of disordered bilayer hexagonal boron nitride quantum films
Authors: Xiao Hua-Ping  , Chen Yuan-Ping  , Yang Kai-Ke  , Wei Xiao-Lin  , Sun Li-Zhong  , Zhong Jian-Xin  ,   Laboratory for Quantum Engineering and Micro-Nano Energy laboratory, Faculty of Materials, Optoelectronics and Physics, Xiangtan University, Xiangtan 411105, China
Published: December 2020

Based on the Anderson tight-binding model, the electronic properties of disordered bilayer hexagonal boron nitride quantum films are investigated. Our numerical results show that the electrons in a disordered bilayer hexagonal boron nitride quantum film are localized, presenting an insulating property. However, for the monolayer disordered bilayer hexagonal boron nitride quantum film, the energy spectrum has persistent mobility edges which are independent of the disorder strength. This indicates that a metal-insulator transition occurs in the monolayer disorder structure. This is similar to the case in an order-disorder separated quantum film. The results could offer useful information for understanding and manipulating the electronic properties of bilayer hexagonal boron nitride quantum films.
Calculation of beam-wave interaction of coupled-cavity TWT using equivalent circuit model
Authors: Bai Chun-Jiang  , Li Jian-Qing  , Hu Yu-Lu  , Yang Zhong-Hai  , Li Bin  ,   National Key Laboratory of Science and Technology on Vacuum Electronics, University of Electronic Science and Technology of China, Chengdu 610054, China
Published: December 2020

A nonlinear model for the numerical simulation of coupled-cavity traveling wave tube is described. The model is based on the Curnow equivalent circuit from which the matrix equations for the fields of any single cavity can be obtained. And the model can be divided into the matrix equations, the motion equations and the space-charge field equations, in which the sever, dynamic tapering in the circuit and the multiple-frequency signal amplification can be also considered. The simulation is used to analyze the nonlinear AM-PM distortion and the intermodulation products of a coupled cavity TWT whose working frequencies range from 59 GHz to 64 GHz. And the analysis of the saturated output power within the frequency band is also included. Comparing the simulation results with the measurements, the percentage difference between the calculation results and the test results is less than 5%.
Highly color-stability flexible white organic light-emitting devices fabricated by color conversion method
Authors: Wu Xiao-Ming  , Shen Li-Ying  , Hua Yu-Lin  , Dong Mu-Sen  , Mu Xue  , Bai Juan-Juan  , Bi Wen-Tao  , Yang Xiao-Yan  , Yin Shou-Gen  ,   School of Materials Science and Engineering, Tianjin University of Technology, Key Laboratory of Display Materials and Photoelectric devices (Ministry of Education), Tianjin Key Laboratory of Photoelectric Materials and devices, Tianjin 300384, China
Published: December 2020

We demonstrate flexible white organic light-emitting diode (WOLED) with high color stability, which combines vacuum deposited blue flexible organic light-emitting diode (FOLED) with red surface color conversion material (CCM). Firstly, we utilize the novel multiple quantum well (MQW), which consists of the alternate layers of 2, 3, 5, 6-Tetrafluoro-7, 7, 8, 8-tetracyano-quinodimethane (F4-TCNQ) and 4, 4', 4"-tris-(N-3-methylphenyl-N-phenylamino) tripheny-lamine (m-MTDATA) as hole injection layer (HIL), through combining a new blue emitting material of N6, N6, N12, N12-tetrap-tolylchrysene-6, 12-diamine (NCA), to fabricate highly efficient blue FOLED. Then, the CCM of 4-(dicyanomethylene)-2-tert-butyl-6-(1, 1, 7, 7-tetramethyljul-oli-dyl-9-en-yl)-4H-pyran (DCJTB) is deposited on the outside of the ITO flexible substrate. Finally, the thickness of the color conversion film (CCF) is optimized to improve the color purity of flexible WOLED. The results demonstrate that at a driving voltage of 7 V, the CIE coordinates of (0.33, 0.27) which are very close to the white equal-energy area are obtained with the thickness of DCJTB of 120 nm. Moreover, the CIE coordinate migrations of the flexible WOLED are less than (±0.02, ±0.02) in a wide range of driving voltages (from 6 V to 11 V) for the device, indicating the flexible WOLED has excellent color stability.
Random walks on spatial networks
Authors: Dou Fei-Ling  , Hu Yan-Qing  , Li Yong  , Fan Ying  , Di Zeng-Ru  ,   Department of Systems Science, School of Management and Center for Complexity Research, Beijing Normal University, Beijing 100875, China
Published: December 2020

In this paper, we construct a cost constrained spatial network by adding long-range connections to the one-dimensional circle. The probability for a long-range connection between nodes i and j is pij dij- ( 0), where dij is the lattice distance and the total length of the long-range connections is set to be =cN(c 0), where c is a positive constant and N is the network size. According to the simulation and numeric results, we find an optimal power-law exponent 0 such that the mean first-passage time is shortest. Furthermore, the shortest mean first-passage time has the power law relationships with the network size N. With the increase of network size N and the total cost , the optimal power-law exponent 0 increases monotonically and approaches 1.5.
The tunneling phenomena of the Fermi superfluid gases in unitarity by manipulating the Fermi-Fermi scattering length
Authors: Ma Ying  , Wang Cang-Long  , Wang Wen-Yuan  , Yang Yang  , Ma Yun-Yun  , Meng Hong-Juan  , Duan Wen-Shan  ,   College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070, China;,   Key Laboratory of Atomic and Molecular Physics and Functional Materials of Gansu Province, Lanzhou 730070, China
Published: December 2020

In the present work, we investigate the tunneling dynamics of superfluid Fermi gas in a double-well potential in a unitarity regime by adjusting the Fermi-Fermi scattering length. The scattering length can affect the quantum transition dramatically. In a certain regime, the complete population transfer between two modes can be obtained. However, in some other regimes, the quantum transition can be completely blocked.
Weak signal detection based on chaos and stochastic resonance
Authors: Gao Shi-Long  , Zhong Su-Chuan  , Wei Kun  , Ma Hong  ,   College of Mathematics and Information Science, Leshan Normal University, Leshan 614000, China;,   College of Mathematics, Sichuan University, Chengdu 610064, China
Published: December 2020

The frequency invariance and phase shift of the first-order steady state moment of system response are deduced for fractional order linear oscillator. Moreover, through the theoretical analysis, the amplification effect of fractional order linear system on the amplitude of first-order steady state moment is verified in stochastic resonance mechanism. Duffing detector is used to realize weak signal detection based on parameter perturbation sensitivity and noise immunity of chaos. Numerical simulations show that this scheme can effectively extract the weak sinusoidal signal from the strong colored noise background and significantly reduce the signal-to-noise ratio threshold in comparison with traditional chaotic detection method.
Application of Chen's system to detecting weak harmonic signals
Authors: Wang Meng-Jiao  , Zeng Yi-Cheng  , Xie Chang-Qing  , Zhu Gao-Feng  , Tang Shu-Hong  ,   Department of Physics and Information Engineering, Hunan Institute of Humanities, Science and Technology, Loudi 417000, China;,   School of Material Science and Photoelectronic Physics, Xiangtan University, Xiangtan 411005, China
Published: December 2020

The detection of weak harmonic signals has important practical value. In this paper, the detection of weak harmonic signals in strong noise is realized with the controlled Chen's system. Dynamics can be divided into slowly varying dynamics and fast varying dynamics, so a slowly varying dynamics is obtained by an averaging method. The critical values of detection parameters are determined, which lead to a sudden change of system dynamical behavior from periodic orbit to stable equilibrium point. Weak harmonic signals can be detected by adjusting the detection parameters and observing the change of system variables. Simulation results show that weak harmonic signals in strong noise can be detected accurately with this system. Compared with existing detection methods with chaotic oscillator, this method is of stronger immunity to noise, and the accurate range of parameter threshold can be obtained through theoretical analysis, which enables its popularization and application in relevant fields.
Peaked soliton solutions and interaction between solitons for the extended (2+1)-dimensional shallow water wave equation
Authors: Ma Song-Hua  , Fang Jian-Ping  ,   College of Science, Lishui University, Lishui 323000, China
Published: December 2020

By an improved Riccati mapping approach and a variable separation approach, a new family of variable separation solutions (including solitory wave solutions, periodic wave solutions, and rational function solutions) of the extended (2+1)-dimensional shallow water wave (SWW) equation is derived. According to the derived solitary wave excitation, we obtain some special peaked soliton structures and study the interaction between solitons.
Method on double-pass acousto-optic frequency shifter in absolute distance measurement using Fabry-Pérot interferometry
Authors: Zhang Li-Qiong  , Li Yan  , Zhu Min-Hao  , Zhang Ji-Tao  ,   State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instruments and Mechanology, Tsinghua University, Beijing 100084, China
Published: December 2020

In order to realize nanometer-scale absolute distance measurements based on Fabry-Pérot interferometry for long-range displacement measurement of the moving coil in Joule balance, the acousto-optic frequency shifter (AOFS) in double-pass configuration is presented, and a tunable frequency difference in a range of 200 MHz is achieved. The focus length of the lens is determined by analyzing the relationship of the tradeoff between the AOFS modulation bandwidth and its diffraction efficiencies; the beam spot of the first-order diffraction beam is guaranteed by accurately positioning the focused beam according to the distribution of the zero-order diffraction beam spot. The experimental single-pass and double-pass peak diffraction efficiency of the AOFS are 79.54% and 61.41%, respectively; the tunable frequency difference of 440-640 MHz, which is twice the single-pass modulation bandwidth output of 220-320 MHz, is obtained by the beat note between the incident beam and the first-order diffraction beam of the double-pass AOFS, and has a good signal-to-noise ratio. Theoretical analysis shows that a folded Fabry-Pérot cavity length displacement of about 53 mm can be measured through the tunable frequency difference achieved by means of double-pass AOFS.
Effects of modulation of atomic injection and exit rate on spatial evolution of phase-dependent lasing without inversion gain and intensity in an open V-type system
Authors: Liang Ying  , Jia Ke-Ning  , Liu Zhong-Bo  , Tong Dian-Min  , Fan Xi-Jun  ,   College of Physics and Electronics, Shandong Normal University, Jinan 250014, China;,   School of Physics, Shandong University, Jinan 250100, China
Published: December 2020

The propagation effect in an open V-type three-level atomic system with spontaneously generated coherence is studied by numerical calculation. The results show that changing the relative phase between the probe and driving field has an important effect on variations of gain and intensity of lasing without inversion (LWI) with propagation distance, i.e. spatial evolution; variation of ratio (S) between the atomic injection rate and atomic exit rate (r0) has a remarkable modulation role in phase-dependent spatial evolution. In a certain range of S (r0), with value of S (r0) increasing, LWI gain and intensity increase and the propagation distance needed for reaching an intensity maximum value becomes longer; In a corresponding closed system, the maxima of LWI gain, intensity and the propagation distance along which the gain can be produced are smaller than in an open system. The Doppler effect also has an obvious influence on spatial evolutions of LWI gain and intensity, values of LWI gain and intensity are smaller in the presence of Doppler effect than in the absence of Doppler effect.
Multiple-type solutions for multipole interface solitons in thermal nonlinear medium
Authors: Peng Hu-Qing  , Ma Xue-Kai  , Lu Da-Quan  , Hu Wei  ,   Laboratory of Photonic Information Technology, South China Normal University, Guangzhou 510631, China
Published: December 2020

We consider a one-dimensional thermal nonlinear medium with a step in the linear refractive index at the sample center. It is found that there exist multipole interface solitons around the interface of the sample. In this paper, we address the existences of three types of solutons for fifth-order and sixth-order interface solitons. The three types of interface solitons have diferent pofiles, beam widths, mass centers, existence and stability regions. The three types of fifth-order solitons each have a stability region, and two of them have the same regions. However for sixth-order interface solions, only one type solution has a stability region.
Experimental study of spread characteristics of droplet impacting solid surface
Authors: Bi Fei-Fei  , Guo Ya-Li  , Shen Sheng-Qiang  , Chen Jue-Xian  , Li Yi-Qiao  ,   Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education, School of Energy and Power Engineering, Dalian University of Technology, Dalian 116024, China
Published: December 2020

The processes of different droplets impacting the solid surface are recorded using a high-speed digital came and the effects of the impact parameters on the droplet impact are studied. The results show that the viscosity of droplet plays a decisive role in spreading process, and surface tension has a leading influence on recoiling process. These two factors jointly determine the oscillation characteristics. The maximum spread factor increases with impact velocity increasing, however, the time from the beginning to achieve the maximum spreading factor shows different variation rules due to surface tension.
Experiments on shock-absorbing capacity of granular matter under impact load
Authors: Ji Shun-Ying  , Li Peng-Fei  , Chen Xiao-Dong  ,   State Key Laboratory of Structural Analysis for Industrial Equipment, Dalian University of Technology, Dalian 116023, China
Published: December 2020

Granular matter is a complex energy dissipation system. The friction and the viscous contacts among particles can dissipate effectively the system energy caused by external impact load. The force chain structure in granular system can extend the local impact in spatial dimension and expand the instantaneous impact in temporal dimension, thus to obtain the effective shock-absorbing effect. To investigate the absorbing capacity of granular matter under an impact load, in the present study, we develop an experimental system, in which a rock ball impacts granular matter in a cylinder under gravity, and the impact force on the cylinder bottom is measured with three load cells. The influences of particle size, material propery, thickness of granular matter on shock-absorbing capacity are discussed. The results show that irregular particles have more shock absorbing capacity, while the large-size particles have a slightly higher shock absorbing capability than the small-size particles. The thickness of granular matter, H, is a key parameter to affect the shock-absorbing. Critical thickness, Hc, is obtained in the experiments. The shock-absorbing capacity of granular matter is enhanced with H increasing when HHc, while H has little influence on shock-absorbing when H>Hc. The resutls above are obtained with constant impact energy. Critical thickness Hc should be a function of impact energy and will be determined in the next study. With the experiments on shock-absorbing capacity of granular matter, it can reveal basic mechanical behaviors of granular materials and be applied in mechanical vibration absorptions.
The study of particle direct loss in tokamak
Authors: Xu Xin-Liang  , Zhao Xiao-Ming  , Wang Zhong-Tian  , Tang Chang-Jian  ,   Physics Depatment of Sichuan University, Chengdu 610065, China;,   Southwestern Institute of Physics, Chengdu 610041, China
Published: December 2020

A new kind of particle in tokamak, which is different from passing partilce and trapped particle, is found. This kind of particle can fly directly out of the boundary due to the drift motion. The loss cone in tokamak, which is composed of these particles, is studied. At the same time, the loss rates due to the banana orbit in different tokamaks are calculated.
Inactivation of A549 cancer cells by a helium-oxygen plasma needle
Authors: Chen Wei  , Huang Jun  , Li Hui  , Lü Guo-Hua  , Wang Xing-Quan  , Zhang Guo-Ping  , Wang Peng-Ye  , Yang Si-Ze  ,   Key Laboratory of Soft Matter Physics, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Science, Beijing 100190, China;,   Fujian Provincial Key Laboratory for Plasma and Magnetic Resonance, School of Physics and Mechanical and Electrical Engineering, Xiamen University, Xiamen 361005, China
Published: December 2020

An inactivation mechanism of A549 cancer cells is studied by using a dielectric barrier discharge (DBD) plasma needle. The influence of oxygen concentration, which is injected into helium plasma afterglow region through a stainless steel tube, is investigated. The neutral red uptake assay provides a qualitative observation of morphological differences between the dead cells and the viable cells after plasma treatment and a quantitative estimation of cell viability under different conditions. In the treatment process at a fixed power of 24 W, the inactivation efficiency of helium-oxygen plasma depends mainly on the exposure time and percentage of added oxygen in helium plasma. Experimental results show that the best parameters of the process are 150 s treatment time, 800 mL/min He with 3% O2 addition and separation of needle-to-sample 3 mm. According to the helium-oxygen emission spectra of the plasma jet, it is concluded that the reactive species (for example, OH and O) in the helium-oxygen plasma play a major role in the cell deactivation.
3D numerical study on volume production efficiency of J-PARC multicusp ion source
Authors: Yang Chao  , Liu Da-Gang  , Xia Meng-Zhong  , Wang Hui-Hui  , Wang Xiao-Min  , Liu La-Qun  , Peng Kai  ,   University of Electronic Science and Technology of China, Chengdu 610054, China
Published: December 2020

In this paper, the particle-in-cell/Monte Carlo method simulation algorithm with independent intellectual property is described in-depth. The discharge properties of the J-PARC multicusp ion source are investigated using this algorithm. The discharge mechanism of the J-PARC ion source is discussed, and the ion source volume production efficiency is analyzed under single correction magnet and double correction magnets. The results show that under the single correction magnet, a maximum volume production efficiency can be obtained when the distance between the center of the correction magnet and the top of the ion source is 50 mm; fixed the top one of double correction magnet, the longer the distance between magnets, the lower the volume production efficiency is.
Problem and modification to the equation of state for liquid and solid-liquid mixed phase in Grover model
Authors: Peng Xiao-Juan  , Liu Fu-Sheng  ,   Laboratory of High Pressure Physics, Southwest Jiaotong University, Chengdu 610031, China
Published: December 2020

According to the definition of disordered entropy, we obtain the equation of state (EOS) of liquid metals. Then due to the fact that the fraction of liquid present in the mixed phase region is assumed to be not linear with temperature but linear with volume, the incorrect hypothesis of the fraction of liquid present in Grover model is clarified. The more accurate formula to express the EOS of solid-liquid mixed phase is obtained. The calculations from Grover model show that the solidus, liquidus and melting line do not coincide in the P-T graph as they should be. The modified results are shown to be in good coincidence with the three lines in the P-T graph.
Numerical investigation of the metal-insulator-metal waveguide filter based on the arc-shaped resonator
Authors: Zhang Zhi-Dong  , Zhao Ya-Nan  , Lu Dong  , Xiong Zu-Hong  , Zhang Zhong-Yue  ,   College of Physics and Information Technology, Shannxi Normal University, Xi'an 710062, China;,   School of Physical Science and Technology, Southwest University, Chongqing 400715, China
Published: December 2020

A metal-insulator-metal waveguide with an arc-shaped resonator is designed, and the transmission properties are numerically investigated by the finite-difference time-domain method. The results show that the transmission peaks in the transmission spectra result from the resonance of the surface plasmon polaritons in the arc-shaped resonator. The effects of the structural parameters of the arc-shape resonator on the transmission properties are also studied. In addition, this structure can also act as a splitter and achieve a dual function of filter and splitter for subwavelength waveguide.
Investigation of the photovoltaic performance of n-ZnO:Al/i-ZnO/n-CdS/p-Cu2ZnSnS4 solar cell
Authors: Xu Jia-Xiong  , Yao Ruo-He  ,   School of Electronic and Information Engineering, South China University of Technology, Guangzhou 510640, China
Published: December 2020

The semiconducting Cu2ZnSnS4 (CZTS) thin film with high absorption coefficient has long been recognized as a novel solar cell material. In this work, the performances of n-ZnO:Al/i-ZnO/n-CdS/p-CZTS solar cells are analyzed by using semiconductor theory. The influences of doping concentration, thickness, and defect states of CZTS layer and the doping concentration and thickness of CdS layer on the performances of the solar cells and the temperature characteristics are investigated. The calculated results show that the CZTS layer is a main absorption layer in the solar cell. The changes in doping concentration and thickness of CZTS layer have significant influence on the conversion efficiency of the solar cell. The density of defect states in CZTS can sharply degrade the photovoltaic performances. The influences of the doping concentration and thickness of CdS layer can be neglected. The calculated results show that the optimal n-ZnO:Al/i-ZnO/n-CdS/p-CZTS structure has open-circuit voltage of 1.127 V, short circuit current density of 27.39 mA/cm2, fill factor of 87.5%, and conversion efficiency of 27.02%. In addition, the temperature gradient of conversion efficiency is -0.14%/K. These results reveal the promising photovoltaic characteristics of CZTS thin film serving as a solar cell absorber.
Evaluating complex network functional robustness by node efficiency
Authors: Zhou Xuan  , Zhang Feng-Ming  , Zhou Wei-Ping  , Zou Wei  , Yang Fan  ,   Engineering College, Air Force Engineering University, Xi'an 710038, China;,   Navy Academy of Armament, Beijing 100161, China;,   Normal College, Tibet Univeristy, Lasa 850000, China
Published: December 2020

In order to overcome the disadvantages of existing complex network robustness research models in which only the local influences of disabled nodes and topological robustness are considered, the node load, utmost load and disabled model are defined by node efficiency and a new method to evaluate complex network functional robustness is proposed in which the whole influence of disabled nodes is considered. The complex network functional robustness is evaluated by the final disabled node proportion after beat and the optimized evaluation arithmetic is given. Experiments show that this method is effective and feasible in evaluation of complex network functional robustness in which the node load is considered, and it is applicable for large scale complex networks.
Piecewise fractional Brownian motion for modeling sea clutter
Authors: Liu Ning-Bo  , Guan Jian  , Huang Yong  , Wang Guo-Qing  , He You  ,   Department of Electronic and Information Engineering, Naval Aeronautical and Astronautical University, Yantai 264001, China
Published: December 2020

In this paper we mainly study the application of piecewise fractional Brownian motion (PFBM) to modeling radar sea clutter. Because the research objects in nature and man-made systems are usually not perfectly fractal in mathematics, the fractal properties of these researched objects cannot hold in the whole scale interval. Traditionally, the mono-fractal model of sea clutter only makes use of the self-similarity of sea clutter within the scale-invariant interval for parameter estimation but ignores the information contained in the scales outside the scale-invariant interval. The PFBM describes the sea clutter piecewisely in frequency domain, which corresponds to describing the sea clutter in time domain respectively on the large scale and on the fine scale. Combining the physical background, the PFBM model can explain the mechanism of the different roughnesses of a sea clutter time sequence respectively on the large scale and on the fine scale. Subsequently, in the paper, we study the effects of moving targets with different Doppler frequencies on sea clutter. The results show that moving targets can cause different effects on sea clutter respectively on the large scale and on the fine scale.
Anti-control and circuit implementation of discrete-time systems under limited regional conditions
Authors: Wang Fang  , Zhang Xin-Zheng  , Shen Chao-Wen  , Yu Si-Min  ,   School of Automation Guangdong University of Technology Guangzhou, 510006 China;,   College of Science, Shandong University of Science and Technology, Qingdao 266590, China;,   College of Information, Zhongkai University of Agriculture and Engineering, Guangzhou 510225, China
Published: December 2020

In the Chen-Lai and Wang-Chen algorithm , the modular functions are both defined in (-∞,+∞). A modular function, however, in the implementation of electronic circuit, is more reasonable in line with the actual situation if it is defined in a finite region. We take for example the anti-control of a discrete time system, of which the modular function is sine function on the basis of a finite region. And in the sense of Li-Yorke, the chaotic sufficient condition and the rigorous theory proof are provided. As a result, ranges of specific circuit parameters can be determined by both the sufficient conditions resulting from the theorem, and a finite region defined by the device, or the constraint conditions of a dynamic range. Therefore, this provides a fundamental basis for the circuit design and its technology. Based on this method, the anti-control circuit of the discrete time system is designed, of which the modular function is sine function in a finite region. And the experimental results are given for confirming the feasibility of the method. The method presented in this paper can also be applied to the circuit implementation and the anti-control of a discrete time system, of which the modular function is other nonlinear function.
Chaotic characteristics analysis and prediction model study on wind power time series
Authors: Zhang Xue-Qing  , Liang Jun  ,   School of Electrical Engineering, Shandong University, Jinan 250061, China
Published: December 2020

In order to reveal the internal dynamic property of wind power time series the nonlinear analysis method is used to identify the chaotic property of wind power set which is the basis for the prediction of the wind power time series. Firstly day correlation property on wind power time series of a certain wind farmer is analyzed. Secondly the largest Lyapunov exponent of wind power set is calculated on the basis of phase space construction to verify the presence of chaos in wind power time series. The ultra-short-term predicted of wind power would produce larger errors by using the Volterra filter multi-step prediction so the predicted results of Volterra filter are corrected by combining the results predicted by Local-region Multi-steps Method and the largest Lyapunov exponent method with weighted Markov chain and ordered operator. Finally the prediction on wind power of a certain wind farmer is presented and the simulation results illustrate that the correction forecasting model improves high predictive accuracy effectively, which provides a useful reference for wind power prediction by the Volterra filter multi-step method.
Rational solutions and spatial solitons for the (2+1)-dimensional nonlinear Schrdinger equation with distributed coefficients
Authors: Ma Zheng-Yi  , Ma Song-Hua  , Yang Yi  ,   College of Science, Lishui University, Lishui 323000, China;,   College of Science, Ningbo University, Ningbo 315211, China
Published: December 2020

The nonlinear Schrdinger equation is one of the most important nonlinear models with widely applications in physics. Based on a similarity transformation, the (2+1)-dimensional nonlinear Schrdinger equation with distributed coefficients is transformed into a traceable nonlinear Schrdinger equation, and then two types of rational solutions and several spatial solitons are derived.
Analysis on topological properties of Beijing urban public transit based on complex network theory
Authors: Zheng Xiao  , Chen Jian-Ping  , Shao Jia-Li  , Bie Li-Dong  ,   China University of Geosciences School of the Earth Sciences and Resources, Beijing 100083, China;,   The Institute of High and New Techniques applied to Land Resources, China University of Geosciences, Beijing 100083, China
Published: December 2020

To analyze the topological properties of Beijing public transport network, until July 2010, we have collected 1165 bus lines and 9618 bus stops of Beijing City (14 districts and 2 counties) as the sample data to build up a directed and weighted complex network model based on neighboring stops by applying the complex network theory. In this model, bus stops are considered as nodes of the complex network, while bus lines connecting two neighboring stops as edges. Consequently, the network has the topological properties of a complex network and meanwhile the nodes (bus stops) have clear geographic coordinates. The complexity of Beijing public transport is then verified through analyzing the topological properties of node degree, node strength, strength distribution, average shortest path, clustering coefficient in the complex network. We find that the distributions of node degrees and node strengths are extremely uneven and the cumulative strength distributions of the top 5% and 10% nodes reach 22.43% and 43.02% respectively. The results also show that the node strength, ordinal number and cumulative strength distribution of the nodes all follow the power-law distribution, showing the network characteristics of scale-free and small world. Some "key nodes" play an important role in network connection. We find two kinds of "key nodes" by using high carrying pressure node analysis and extract regional central analysis. These rules provide new references for optimizing the urban transport network, managing traffic congestion and planning and developing the traffic.
Scintillating properties of Ce3+-doped high density oxide glasses
Authors: Yang Bin  , Zhang Yue-Pin  , Xu Bo  , Lai Fei  , Xia Hai-Ping  , Zhao Tian-Chi  ,   Laboratory of Photo-Electronic Material, Ningbo University, Ningbo 315211, China;,   Department of Physics, University of Washington, Seattle, WA 98195, USA
Published: December 2020

The SiO2-B2O3-Al2O3-Gd2O3 system based samples doping with rare earth Ce3+ ions (cations) are synthesized by high-temperature melting method. The effects on their density, transmission and scintillating properties are investigated. The results indicate that all the samples, especially those that have high densities, have good physical properties. The emission peak wavelengths of all samples excited by X-ray are at 390 nm. Increasing the concentrations of Ce3 + and Gd3+ ions has a positive effect on luminescence properties. However, when the concentration of Ce3+ ions arrives at 1 mol%, with the increase of the concentration of Ce3+, the emission peak decreases. When Gd3+ ions concentration reaches a certain value scintillating properties decreases with Gd3+ ion concentration increasing. The X-ray-induced luminescence intensity of the sample of SBAG4 is about 90% that of BGO crystal. Gd3+ ions can sensitize the luminescence of Ce3+, the best concentration of Ce3+ ions is 1 mol% and the best concentration of Gd3+ ions is 15 mol%. These samples are attractive for some physical applications.
Influence analysis of saturation effect of microchannel plate on dynamic range of streak cameras
Authors: Pan Jing-Sheng  , Qi Lu  , Xiao Hong-Liang  , Zhang Rong  , Zhou Jian-Xun  , Pu Dong-Dong  , Lü Jing-Wen  ,   School of Materials Science and Engineering Changchun University of Science and Technology, Changchun 130022, China;,   North Night Vision Tech. Corp.Ltd. Nanjing Branch, Nanjing 211106, China
Published: December 2020

The streak cameras which with an internal or external microchannel plate (MCP) image amplification has a significant enhancement on the detect signal threshold, but also induces the saturation effect of MCP to limit the dynamic range of streak camera. The saturation effect of MCP is described through the channel multiplier model of a discrete resistance capacitance dynode chain, explaining that the input output linear range of MCP which in both the two amplification method is depend on the charge restored in the channels the contribution of compensate effect which comes from the bias current is very limited, even using a low restistance MCP in the external method streak camera, so the streak cameras with an internal and external MCP image amplification should have equivalent dynamic range, low resistance MCP only function if a rapid sequence shots is required, and MCP gain was set up properly is critical for the dynamic range of streak camera.
Recent development of polymer/fullerene photovoltaic cells
Authors: Gao Bo-Wen  , Gao Chao  , Que Wen-Xiu  , Wei Wei  ,   State Key Laboratory of Transient Optics and Photonics, Xi'an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences , Xi'an 710119, China;,   School of Electronics and Information Engineering, Xi'an Jiaotong University, Xi'an 710049, China;,   Xi'an Modern Chemistry Research Institute, Xi'an 710065, China
Published: December 2020

Polymer photovoltaic cells with organic polymer materials as the active layers for an increasing power conversion efficiency have become a research hotspot in the field of photovoltaic devices in recent years. In this paper, Internal mechanism of polymer/fullerene solar cells are elaborated exhaustively, including light absorption, exciton diffusion and dissociation and charge carrier transport as well as extraction. Furthermore, the optimization of device structure, morphology control and interface modification are introduced to improve performance of polymer/fullerene solar cells. Power conversion efficiency and the various structures which can be achieved are discussed in detail. The future prospects of polymer photovoltaic cells are also expected.
Investigation of one-dimensional finite phononic crystal with exponential section
Authors: Fu Zhi-Qiang  , Lin Shu-Yu  , Chen Shi  , Xian Xiao-Jun  , Zhang Xiao-Li  , Wang Yong  ,   Institute of Applied Acoustics, Shaanxi Normal University, Xi'an 710062, China;,   China Electronics Technology Group Corporation 26th Research Institute, Chongqing 400060, China
Published: December 2020

In this paper, we study the propagation of elastic longitudinal wave in one-dimensional (1D) finite periodic phononic crystal with exponential section, and obtain the expression of frequency response function. Comparing the 1D phononic crystal with constant section, we find that the value of attenuation inside the band gap decreases quickly as the cross-sectional area of output and increases, at the same time, the initial frequency decreases and the cut-off frequency increases, i.e. the width of the band gap will increase. The effects of the lattice constant and the filling fraction on band gap are also analyzed. The change trends of the initial frequency and cut-off frequency are consistent with those of constant section. We hope that the investigation of this paper will be helpful for the phononic crystal in practical application such as vibration shield.
Tunable negative refraction properties of photonic crystals based on silicon columns arranged in magnetic liquids
Authors: Yu Guo-Jun  , Pu Sheng-Li  , Wang-Xiang  , Ji Hong-Zhu  ,   College of Science, University of Shanghai for Science and Technology, Shanghai 200093, China
Published: December 2020

Tunable negative refraction of two-dimensional photonic crystal made of silicon cylinders hexagonally arranged in a MnFe2O4 magnetic liquid is studied. The plane wave expansion and finite-difference time-domain method are used to calculate and simulate its band structure, equi-frequency surface and negative refraction property. For the TE mode, the negative refraction of the two-dimensional photonic crystal made of the silicon column-magnetic liquid system can be tuned by a magnetic field. When the volume fraction of magnetic nanoparticles within the magnetic liquid and the frequency of the incident light are fixed, the deflection angle of the refraction light and the absolute value of the negative refractive index increase gradually with the external magnetic field increasing. When the volume fraction of magnetic nanoparticles within the magnetic liquid and the strength of the external magnetic field are fixed, the absolute value of the negative refractive angle and negative refractive index decrease with the normalized frequency of the incident light increasing. In addition, when the external magnetic field and the normalized frequency of the incident light are fixed, the negative refraction weakens with the increase of magnetic nanoparticle volume fraction of background solution.
Atmospheric pressure streamer and glow-discharge generated alternately by pin-to-plane dielectric barrier discharge in air
Authors: Yu Zhe  , Zhang Zhi-Tao  , Yu Qing-Xuan  , Xu Shao-Jie  , Yao Jing  , Bai Min-Dong  , Tian Yi-Ping  , Liu Kai-Ying  ,   Institute of Marine Engineering, Dalian Maritime University, Dalian 116026, China;,   Department of Physics, Dalian Maritime University, Dalian 116026, China
Published: December 2020

Performance of producing a high energy electron can be improved, if the glow discharge is generated in a system of dielectric barrier discharge. In this paper, different discharge modes of pin-to-plane dielectric barrier discharge are investigated in atmospheric pressure. Different discharge modes are observed in the positive half-period and negative half-period of the discharge. When and applied voltage is 3 kV, a streamer mode appear in the positive half-period and a corona (or Trichel discharge) mode occurs in negative half-period. When the applied voltage is 6 kV, a streamer emerges in the positive half-period and a micro glow discharge is present in the negative half-period. The micro glow discharge has hierarchical structure like that typical low pressure glow discharge produces. The generation of micro glow discharge is due to, enough strong cathode electric field strength and effective secondary electron emission process around naked negative electrode. The glow discharge transforming to arc discharge is avoided due to dielectric layer.
Effect of cooling rate on layering ICF cryogenic ice characterized by backlit shadowgraphy
Authors: Wang Kai  , Lin Wei  , Liu Yuan-Qiong  , Xie Duan  , Li Jun  , Ma Kun-Quan  , Tang Yong-Jian  , Lei Hai-Le  ,   Research Centre of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

The effect of cooling rate on layering the deuterium ice inside inertial confinement fusion (ICF)spherical cryotarget is studied by backlit shadowgraphy. Experimentally, the temperature of ice is first determined by the calibration of temperature field around ICF cryotarget. The solidification process of deuterium in the cryotarget is in- situ characterized by backlit shadowgraphy. The power-spectrum density of the bright ring in shadowgraphy at different cooling rates is obtained. Experimental results demonstrate that the step-gradient slow cooling is favorable for forming uniform fuel ice in comparison with the rapid cooling. Furthermore, the validity of characterizing the ICF cryotarget layering by the backlit shadowgraphy is also verified.
Microstructure of spray-formed superalloy FGH4095
Authors: Zhang Yu  , Ge Chang-Chun  , Shen Wei-Ping  , Qiu Cheng-Jie  ,   Institute of Special Ceramics and Powder Metallurgy, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China
Published: December 2020

Spray-forming technology can produce billets with similar microstructure and higher productivity compared with the P/M process. The nickel based superalloy FGH4095 billet was produced by spray-forming with nitrogen as atomization gas. The pressure of the atomization gas and the temperature of the deposit zone were recorded. The compactness of the deposit was characterized by quantitative metallography and Archimedes method. The grain structure of substrate and the size and morphology of ' phase were observed. Results show that the density of the deposit produced by nitrogen spray forming reaches about 99% and little amount of pores with diameters about 12 m could be detected in the deposit matrix. While, pores could be enclosed by HIP and near iso-thermal forging process; Nitrogen was existed as carbonitride with diameters less than 1 m. The average grain size of the equiaxed grains in the interior of the deposit is about 2040 m, while the grains near the surface of the deposit are finer with average grain size about 13um; the primary ' phase which has diameters about 0.30.5 m possesses irregular block feature. The microstructure of the spray deposit is related to the temperature history of the alloy during the spray forming process.
The effects of different particle size Y2Ba4CuBiOy nanoparticles doped on the properties of single domain YBCO bulk superconductors by TSIG process
Authors: Wang Miao  , Yang Wan-Min  , Zhang Xiao-Ju  , Tang Yan-Ni  , Wang Gao-Feng  ,   Shaanxi Normal University, College of Physics and Information Technology, Xi'an 710100, China
Published: December 2020

Single domain YBCO bulk superconductors are fabricated by the top-seeded infiltration and growth process(TSIG). The effects of different particle size Y2Ba4CuBiOy nanoparticles doped on the growth morphology, microstructure and levitation force of single domain YBCO bulk superconductors are investigated. The mean diameters of the initial Y2Ba4CuBiOy nanoparticles respectively are 283 nm, 170.4 nm and 82.5 nm, and the amount of Y2Ba4CuBiOyadded to Y2BaCuO5 is 2 wt%. The results show that the single domain YBCO bulk superconductors can be fabricated, and the surface of the sample has significant cross pattern and four single domain sectors become smooth and flat. The second phase Y2Ba4CuBiOy nanoparticles are well-distributed into the single domain YBCO bulk samples, and the particles sizes of Y2Ba4CuBiOy nanoparticles in the YBCO bulk sample are respectively 270 nm, 150 nm and 50 nm, smaller than that the initial powder. The magnetic levitation forces of the samples increase gradually with the decrease of initial powders of Y2Ba4CuBiOy nanoparticles, which are respectively 10 N, 17 N and 22 N. The results are very important for further studying the method of flux pinning of nanoparticles and improving the properties of YBCO bulk superconductors.