bluuebunny/crossref_metadata_2025 huggingface dataset:
Generalized linear reconstructing algorithm based on homomorphic signal processed in digital holographic microscopy
Authors: Wang Hua-Ying  , Yu Meng-Jie  , Liu Fei-Fei  , Jiang Ya-Nan  , Song Xiu-Fa  , Gao Ya-Fei  ,   College of Science, Hebei University of Engineering, Handan 056038, China;,   School of Information & Electrical Engineering, Hebei University of Engineering, Handan 056038, China;,   Class 06121001, Specialty of Electrical Engineering and Automation, College of Automation, Beijing Institute of Technology, Beijing 100081, China
Published: December 2020

In order to improve the accuracy and the speed of reconstructing an image, the digital holographic generalized linear reconstructing algorithm based on homomorphic signal processing is proposed. By using the pre-magnification digital holographic imaging system and the principle of homomorphic signal processing, the proposed algorithm is analyzed theoretically. The achieving condition for and reconstructing process of the proposed algorithm is presented. Then the theoretical results are demonstrated by simulations and experimental data. Results show that the zero-order term of digital hologram frequency spectrum can be eliminated effectively by the proposed algorithm so as to realize the high-precision reconstruction of the digital hologram. Because a whole quadrant is chosen as the filtered area, the manual frequency filtering operation needed in common linear reconstructing algorithm is avoided and then the reconstructing speed is improved greatly. Meanwhile, the high-frequency component of the reconstructed original image can be reserved up to the hilt so that the high resolution image can be achieved.
PN-based single carrier block transmission with iterative frequency domain equalization over underwater acoustic channels
Authors: He Cheng-Bing  , Huang Jian-Guo  , Meng Qing-Wei  , Zhang Qun-Fei  , Shi Wen-Tao  ,   College of Marine Engineering, Northwestern Polytechnical University, Xi’an 710072, China
Published: December 2020

Single carrier modulation with time-domain equalization (SC-TDE) in underwater acoustic channel is sensitive to receiver parameters and its computational complexity is very high. Orthogonal frequency division multiplexing (OFDM) signal has high peak-to-average power ratio (PAPR) and is sensitive to Doppler shift. Aiming at these problems, this paper proposes the pseudo-noise (PN)-based single carrier block transmissions through underwater acoustic channels and corresponding receiver algorithms. The receiver employs PN signals for residual Doppler shift estimation, and channel estimation. A low complexity T/4 fractional iterative frequency domain equalizer is introduced to improve the system performance. One underwater acoustic communication system has been designed and tested in a lake in November 2011. At a distance of 1.8 km under a complex channel condition, the useful data rates of around 1500 and 3000 bps are achieved with un-coded bit error rates 10-2–10-4 in the lake experiment.
Investigation on the capillary evaporation process based on the existence of liquid film
Authors: He Feng  , Wang Zhi-Jun  , Huang Yi-Hui  , Ye Peng  , Wang Jin-Cheng  ,   State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072, China
Published: December 2020

The capillary evaporation process with stable liquid film along the cell wall is investigated by evaporating under constant temperature. The experimental results show that the liquid/vapor interface coincides with viscous finger, which is independent of the state of liquid film and evaporating rate. During the evaporation process, four stages are found: sharp falling rate stage, constant rate stage, linear falling rate stage and boundary effect stage, which are corresponding to different kinds of liquid film states. The evaporating takes place mainly at the tip of the liquid film region, and the stable liquid film transports the liquid from the liquid region to the capillary tube orifice.
First principles study of Au-Sn intermetallic compounds
Authors: Hu Jie-Qiong  , Xie Ming  , Zhang Ji-Ming  , Liu Man-Men  , Yang You-Cai  , Chen Yong-Tai  ,   State Key Laboratory of Advanced Technologies for Comprehensive Utilization of Platinum Metals, Kunming Institute of Precious Metals, Kunming 650106, China
Published: December 2020

A first-principles plane-wave pseudopotential method based on the density functional theory is used to investigate the energies, electronic structures, and elastic properties of intermetallic compounds of Au-Sn system. The enthalpies of formation, the cohesive energies, and elastic constants of these compounds are estimated from the electronic structure calculations, and their structural stabilities are also analyzed. The results show that the Au5Sn compound is unstable with respect to other compounds, and the bonding effects of AuSn2 and AuSn4 are stronger than those of AuSn and Au5Sn, for there are the strong hybridizations between Au and Sn atoms in AuSn2 and AuSn4 compounds. The main bonding effect of AuSn is Sn–Sn bonding interaction, and due to the Au content being maximal in Au5Sn the bonding of p electrons in Sn conduction band is suppressed by the covalent bonding of Au–Au.
Experimental and theoretical investigation of transparent and conductive B doped ZnO film
Authors: Wang Yan-Feng  , Zhang Xiao-Dan  , Huang Qian  , Yang Fu  , Meng Xu-Dong  , Song Qing-Gong  , Zhao Ying  ,   College of Science, Hebei North University, Zhangjiakou 075000, China;,   Key Laboratory of Photo-Electronic Thin Film Devices and Technology of Tianjin, Key Laboratory of Opto-Electronic Information Science and Technology, Ministry of Education, Institute of Photo-Electronic Thin Film Devices and Technology of Nankai University, Tianjin 300071, China;,   College of Science, Civil Aviation University of China, Tianjin 300300, China
Published: December 2020

The properties of boron doped ZnO (BZO) films are investigated by the pulsed DC magnetron sputtering technique and the plane wave pseudo-potential method based on the density-functional theory. Highly conductive and transparent BZO thin films are prepared using a B2O3:ZnO ceramic target. The effects of the substrate temperature on the structureand electrical and optical properties are systematically investigated. The results show that by increasing the substrate temperature appropriately, the crystallinity, grain size, and carrier mobility of BZO film are improved, and the resistivity is reduced. BZO films of low resistivity (7.03×10-4 Ω·cm) and high transmittance (89%) from 400–1100 nm are achieved at an optimal substrate temperature of 200 ℃. The theoretical results show that B is doped in ZnO mainly in three forms, i.e., in the forms of substitutional BZn atoms, octahedral interstitial site (BIO), and tetrahedral interstitial site (BIT). Among them the formation energy of BZn defect is lowest, and its concentration may be the highest in all the sample concentrations. After incorporation of B, the Fermi level goes through the conduction band. The sample shows a typical n-type metallic characteristic and the optical band gap increases significantly. The carriers originate from the orbits of B 2p, O 2p and Zn 4s.
A dissipative dynamical method based on discrete variational principle：stationary shapes of three-dimensional vesicle
Authors: Xia Bin-Kai  , Li Jian-Feng  , Li Wei-Hua  , Zhang Hong-Dong  , Qiu Feng  ,   State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Sceince, Fudan University, Shanghai 200433, China;,   Kavli Institute for Theoretical Physics, Chinese Academy of Sciences, Beijing 100190, China
Published: December 2020

In this article, the dissipative dynamical evolution method based on the discrete variational principle is applied to a three-dimensional (3D) vesicle system. The stationary shapes of vesicles are obtained through the minimization of membrane bending energy without any symmetric assumption, which is an outstanding merit of our method. Aiming at a 3D vesicle system with certain parameter settings, a series of axisymmetric shapes are achieved by our method. The simulation results are in good agreement with those obtained with axisymmetric assumption, which indicates that our method can describe the deformation of 3D vesicle with extremely high precision. In addition, a shape transition between two stable states with great difference is studied, which further implies the capability of our proposed method in simulating large deformations regarding the 3D membrane. We believe that we have provided a very powerful simulation method for the future studies of bio-membrane deformations.
Electromagnetic scattering characteristic of aluminous targets in the terahertz and far infrared region
Authors: Wang Rui-Jun  , Deng Bin  , Wang Hong-Qiang  , Qin Yu-Liang  ,   School of Electronic Science and Engineering, National University of Defense Technology, Changsha 410073, China;,   876 Air Force Troop PLA, Zhangye 734100, China
Published: December 2020

In the terahertz and far infrared region, aluminum is in a state of transition from conductor to dielectric, and the research of the interaction between aluminous target and electromagnetic wave is meaningful for scattering prediction of targets. With the available error criterion model, dielectric function of aluminum is determined by fitting to experimental data in the terahertz and far infrared region. The transmitted parameters in aluminum are deduced by considering different loss mechanisms. Reflection and transmission characteristics on the interface of aluminum are investigated, and the reflection coefficients are given as a function of frequency. Results show that the transmitted parameters in aluminum keep their continuity and coherency from microwave to terahertz frequency. RCS (radar cross-section) results of aluminum plates computed by IBC method demonstrate that the increased wave impedance of aluminous targets has little impact on its backscattering, and the polished aluminous plate or sphere can still be treated as a perfect electrical conductor and used as a reference for RCS calibration.
Design and optimization of broadband polarization beam splitter made from a wave-structured multilayer film
Authors: Peng Hao  , Shen Wei-Dong  , Yang Chen-Ying  , Zhang Yue-Guang  , Liu Xu  ,   Department of Optical Engineering, Zhejiang University, State Key Laboratory of Modern Optical Instrumentation, Hangzhou 310027, China
Published: December 2020

Based on the 2D-PC wave multilayer film structure, a method to broaden the bandwidth of polarization beam splitter is proposed, which is composed of two different thickness periodic film stacks. Combined with the evaluation function of polarization splitting characteristic, the particle swarm optimization method is employed to design the optimal structural parameters. A broadband and compact polarization beam splitter is acquired, in which the center wavelength is 565 nm and its working range has achieved 220 nm with the average extinction ratio over 30 dB. In addition, by using the finite difference time domain method, the band structure and transmission spectrum of the wave-structure multilayer film are calculated, the angle sensitivity of the structure is investigated in detail. And we also study the electromagnetic field in the wavy-structure. Simulation results prove that the structure composed of the two different thickness periodic film stacks can avoid the discontinuity of bandgap, and PSO method can accelerate the convergence of the optimization algorithm and extend the bandwidth effectively.
Modification of surface morphology of a textured silicon substrate and its application in heterojunction solar cells
Authors: Zhao Zhen-Yue  , Zhang Xiao-Dan  , Wang Feng-You  , Jiang Yuan-Jian  , Du Jian  , Gao Hai-Bo  , Zhao Ying  , Liu Cai-Chi  ,   Institute of Photo-Electronic Thin Film Devices and Technology of Nankai University, the Key Laboratory of Optoelectronic Thin Film Devices and Technology of Tianjin City, The Key Laboratory of Optoelectronic Information Technical Science of Ministry of Education, Tianjin 300071, China;,   Institute of Information Functional Material of Hebei University of Technology, Tianjin 300130, China
Published: December 2020

Texture on a mono-crystalline silicon substrate can effectively enhance the light trapping, and increase the short-circuit current of silicon hetero-junction solar cell. However, when the amorphous silicon layer deposited on the crystalline silicon substrate, the amorphous and crystalline epitaxial growth of mixed phases is created in the valleys with sharp edges, which leads to reducing the output characteristic parameters of the solar cell. In this paper, we use two methods to modify the microstructure of the textured substrate, and apply them to the silicon heterojunction solar cell. The textured silicon substrate is smoothed through the mixed acid, which makes the pyramid shape become round off and the open circuit voltage of the solar cell change from 564.6 mV to 609.4 mV. In addition, we use tetramethyl ammonium hydroxide (TMAH) instead of alkali solution. It is found that the textured substrate has an effective light trapping, and its micro-morphology is more rounded, the short-circuit current and open circuit voltage of the solar cell have been improved significantly.
Study on the lumped parameters of FSS in terms of the transfer function
Authors: Jiao Jian  , Gao Jin-Song  , Xu Nian-Xi  , Feng Xiao-Guo  , Hu Hai-Xiang  ,   Key Laboratory of Optical System Advanced Manufacturing Technology, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China;,   University of Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

Equivalent circuit method is a principal one to analyze the active frequency selective surface (FSS). Extracting its lumped parameters is the key to the equivalent circuit method. We have constructed the transfer function based on the traditional equivalent circuit method and the transmission line theory. A matrix equation composed of lumped parameters is set up utilizing the relationship between the equivalent impedance and transmission peak. The equivalent lumped parameters are solved by the least square method, and the FSS frequency response curves are obtained from the transfer function. Compared with the full wave analysis method, the calculated results are in good agreement with that of simulation. Such results verify the accuracy and reliability of the method presented in this paper, and provide a theoretical reference to active FSS analysis using the equivalent circuit method.
Financial networks model based on random matrix
Authors: Han Hua  , Wu Ling-Yan  , Song Ning-Ning  ,   Department of Science, Wuhan University of Technology, Wuhan 430070, China
Published: December 2020

Random matrix theory is applied to study the correlation between different financial correlation coefficient matrices in the financial field. Correlation coefficient matrix is a key factor for constructing a network. In this paper we relate the random matrix theory to the network construction to study the financial networks model in terms of the random matrix. We select the stock data of Shanghai stock market, and divide them into four stages. We discuss the statistical properties of eigenvalues in financial correlation coefficient matrix and random matrix based on the random matrix theory, and improve the existing denoising method to construct the correlation coefficient matrix and to make it more suitable for building financial networks. After that we can build the financial network model. Then we analyze and compare the original financial network, the denoising financial network and the noise financial network in terms of the random matrix theory and the key node of networks. It is found that the primary important information is still in the original network, and the noise information corresponds to the information which the nodes of small degree in the original network include. Finally we analyze the topological structure of the financial networks, such as the minimum spanning tree, the motif and community structure. We also find that the topological properties of the improved financial networks are more remarkable and the topological structure is more compact.
Distributed encirclement control of multi-agent systems
Authors: Duan Min  , Gao Hui  , Song Yong-Duan  ,   School of Automation, Chongqing University, Chonging 400044, China
Published: December 2020

In nature, the motion of swarm intelligence has a regularity such as the line motion based bird migration, the circle motion based fish swarming, etc., which has important theoretical significance and vast application prospect in engineering practice. In this paper, we investigate the distributed encirclement control problem of a group of multi-agent systems. With considering the feature that each agent can achieve local target information, we design an averaging estimator to achieve the target information, and propose a distributed control scheme to achieve the encirclement and keep the formation changing with the target states. By Lyapunov theory analysis, it is proved that each individual agent can achieve the information about the marked arerage position in a finite time, encircle and pursue the targets based on the encirclement formation. Finally, a numerical example is presented to illustrate the obtained theoretical results.
A chaotic signal reconstruction algorithm in wireless sensor networks
Authors: Huang Jin-Wang  , Li Guang-Ming  , Feng Jiu-Chao  , Jin Jian-Xiu  ,   School of Electronic and Information engineering, South China University of Technology, Guangzhou 510641, China;,   School of Computer Science, Dongguan University Of Technology, Dongguan 523808, China
Published: December 2020

A chaotic signal in an observation area of network nodes is sent to a fusion center for reconstruction. As the communication bandwidth is limited, the signal must be quantified before sending to the fusion center, which will add quantization noise to the observed signal, which makes the signal reconstruction more difficult. A chaotic signal reconstruction algorithm is proposed in this paper based on square-root cubature Kalman filter. Firstly the probability density function of the observed signal is estimated, and then the optimal quantizer is used to quantify the observed signal. Under the limited budget of quantization bits, the best performance can be achieved. Compared with the unscented Kalman filter counterpart, our algorithm has fewer cubature points and has the merit of small computation load; meanwhile, it uses the square root of error variance for iteration, this will be more stable and accurate when iterating for parameter estimation. Simulation results show that the algorithm can reconstruct the observed signal quickly and effectively, with consuming less computation time and being more accurate than the one based on unscented Kalman filter.
Simulation of frequency discrimination for spaceborne Doppler wind lidar (Ⅱ)：Study on the retrieval of atmospheric wind speed for Rayleigh channel based on Fabry-Perot interferometer
Authors: Zhang Ri-Wei  , Sun Xue-Jin  , Yan Wei  , Zhao Jian  , Liu Lei  , Li Yan  , Zhang Chuan-Liang  , Zhou Jun-Hao  ,   College of Meteorology and Oceanography, PLA University of Science and Technology, Nanjing 211101, China;,   Northwest Institute of Nuclear Technology, Xi'an 710024, China
Published: December 2020

Based on the principle of spaceborne Doppler wind lidar, a simulation system of frequency discrimination is built based on the double sequential Fabry-Perot (F-P) interferometer. The wind retrieval algorithm of Rayleigh channel is simulated and studied. The influence on the retrieved atmospheric line-of-sight (LOS) wind speed in Rayleigh channel by the Rayleigh-Brillouin effect and Mie contamination is systematically analyzed. The horizontal line-of-sight (HLOS) wind error is analysed using the simulated result of the radiosonde dataset. The results show that the wind speeds of the middle and upper atmosphere can be retrieved in Rayleigh channel based on the double sequential F-P interferometer; the Rayleigh-Brillouin effect and Mie contamination influence the accuracy of LOS wind speed retrieval in Rayleigh channel; the Rayleigh channel requires more accurate temperature; Mie contamination can be ignored in clear atmosphere; when Brillouin effect is not considered, below 2 km, the HLOS wind speed cannot be retrieved in Rayleigh channel, and above 2 km, the HLOS wind speed error in Rayleigh channel is less than 0.4 m/s and its standard deviation is 1-4 m/s. Just as the Mie channel, distributions of aerosol and cloud have an influence on wind error for spaceborne Doppler wind lidar in Rayleigh channel. The research results have an important reference value for the development of spaceborne lidar wind technology.
Narrow linewidth laser system used for the intercombination transition spectrum measurement
Authors: Gao Feng  , Liu Hui  , Xu Peng  , Wang Ye-Bing  , Tian Xiao  , Chang Hong  ,   Key Laboratory of Time and Frequency Primary Standards of Chinese Academy of Sciences, National Time Service Center of Chinese Academy of Sciences, Xi'an 710600, China;,   University of Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

We observe the intercombination transition spectrum of alkaline-earth strontium, using a stable narrow 689 nm laser which is locked to a high fineness ultralow expansion reference cavity. The finesse is measured using cavity ring down techniques in different transverse modes of the cavity. Additionally, the response time of optical switch and PD monitor are taken into consideration in the measurement. Using a fiber-based optical frequency comb, the Allan deviation calculated from the counter value of the beat frequency shows a stability of 2.8× 10-13 in a 1 s averaging time. The saturation spectrum is measured with a minimum sub-Doppler width of 55 kHz. The high resolution intercombination transition spectrum can be used for absolute frequency stabilization.
W43A Jet：strongly related to the magnetic field testified in laboratory
Authors: Pei Xiao-Xing  , Zhong Jia-Yong  , Zhang Kai  , Zheng Wu-Di  , Liang Gui-Yun  , Wang Fei-Lu  , Li Yu-Tong  , Zhao Gang  ,   Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012, China;,   Department of Astronomy, Beijing Normal University, Beijing 100875, China;,   Institute of Applied Physics and Computational Mathematics, Beijing 100094, China;,   Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
Published: December 2020

Dual Al plasma jets are generated with eight Shenguang Ⅱ lasers. With Euler MHD scale law we find that the jet produced in the laboratory is highly similar to astronomical observations after transformation. We propose that the reconnection electric filed should have a possible direct influence on the formation and collimation of the plasma jet.
Simulation of erosion of the tungsten wall by impurities in the divertor plasma
Authors: Sun Zhen-Yue  , Sang Chao-Feng  , Hu Wan-Peng  , Wang De-Zhen  ,   Key Laboratory of Materials Modification by Laser, Ion and Electron Beams (Ministry of Education), School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116023, China
Published: December 2020

Divertor is a component that directly contacts the plasma in tokamak. To ensure the lifetime of the device, it is necessary to reduce the erosion of the divertor wall by plasma. In this work, a particle-in-cell model is used to study the influences of plasma temperature and impurity concentration on the erosion of tungsten divertor wall by carbon and beryllium ions. The steady-state sheath, particle and energy fluxes to the wall, and the energies and angle of the incident ions can be obtained. Then, these data can be used as the input parameters for the plasma-surface interaction model, to evaluate the erosion rate of the plate based on the empirical formulas for physical sputtering. It is found that the erosion by heating plays a negligible role under the plasma condition of this work. Due to the low physical sputtering threshold energy of tungsten by impurities and the impurity ions accelerated by sheath, the physical sputtering of the tungsten by the impurities plays an dominant role in the total erosion. In addition, the erosion rate increases with the increase of plasma temperature and impurity concentration.
Spatiotemporal distribution of hydrogenous electrode vacuum arc discharge plasma
Authors: Feng Jing-Hua  , Meng Shi-Jian  , Fu Yue-Cheng  , Zhou Lin  , Xu Rong-Kun  , Zhang Jian-Hua  , Li Lin-Bo  , Zhang Fa-Qiang  ,   Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

Vacuum arc ion sources have been used in a wide range including vacuum coating, materials surface modification, switching devices and other fields. At present, researches on the vacuum arc ion source are mainly targeting the pure metal or alloy electrodes, but the researches on the hydrogenous electrode are rarely reported. The axial and radial distributions of the hydrogenous electrode vacuum arc discharge plasma are studied by using high speed four-frame camera equipped with the narrow-band filters of strong lines of H I and Ti I. It is found that the anode is intensively luminous in the vacuum breakdown. The observation from the camera with the filter reveals that the vacuum breakdown is ignited mainly by the anode hydrogen desorption. The vacuum arc is sustained by plasmas emitted from either the cathode spots or the electrode inner wall. The cone-shaped cathode spot located at the cathode-insulator-vacuum junction is the main plasma source. It is found that the distribution of hydrogen atoms is much more homogeneous than that of titanium atoms, which may be due to the earlier beginning of hydrogen desorption, the bigger emitting area and faster diffusion speed of hydrogen atom.
First-principle study on the effects of Tl doping on the band gap and the band-edge of optical absorption of InI
Authors: Xu Zhao-Peng  , Wang Yong-Zhen  , Zhang Wei  , Wang Qian  , Wu Guo-Qing  ,   School of Information Science and Engineering, the Key Laboratory for Special Fiber and Fiber Sensor of Hebei Province, Yanshan University, Qinhuangdao 066004, China
Published: December 2020

According to the density functional theory, using first-principles plane-wave ultrasoft pseudopotential method, models for a pure InI and different concentrations of Tl-doped InI are set up, and the geomertry optimizations for the modes are carried out. The total density of states, the band structures and the optical absorption are also calculated. The results show that the smaller the doping concentration of Tl, the smaller the formation energy of InI is, thus the more stable the crystal structure is. The Tl doping causes the bottom of conduction band shift to a higher energy, while the location of the top of valence band has no change. This makes the band gap of InI broadened, and the absorption spectrum obviously blue-shifted.
Magnetic and transport properties of layered perovskite manganites (La1-xEu x)4/3Sr5/3Mn2O7(x=0, 0.15)
Authors: He Li-Min  , Ji Yu  , Lu Yi  , Wu Hong-Ye  , Zhang Xue-Feng  , Zhao Jian-Jun  ,   Inner Mongolia Key Laboratory of Magnetism and Magnetic Materials, Department of Physics, Baotou Normal University, Baotou 014030, China;,   Inner Mongolia Key Laboratory for Utilization of Bayan Obo Multi-Metallic Resources: Elected State Key Laboratory, Inner Mongolia University of Science and Technology, Baotou 014010, China
Published: December 2020

The samples (La1-xEux)4/3Sr5/3Mn2O7 (x=0, 0.15) were prepared by the traditional solid-state reaction, and their magnetic and electrical properties were investigated. The magnetzation measurement reveals that as temperature lowers, all the samples undergo a complex magnetic transition process: they transform from the two-dimensional short-range ferromagnetic order at T* into the three-dimensional long-range ferromagnetic state at TC. With the increase of Eu doping, T* and TC are both reduced, and the sample (La0.85Eu0.15)4/3Sr5/3Mn2O7 exhibits spin-glass-like behaviour in a low temperature region. Electrical property measurements show that with the increase of Eu concentration, resistivity sharply increases, the metal-insulator transition temperature decreases and the magnetoresistance peak increases. These effects are attributed to the decrease of the average ionic radius diminution and the lattice distortion due to the substitution of the smaller Eu3+ ions for La3+ ions. In addition, the small-sized Eu3+ ion preferentially occupies the R site in the rock-salt layer, then the distributions of La3+, Sr3+, Eu3+ ions in the sample (La0.85Eu0.15)4/3Sr5/3Mn2O7 should be more orderly, so there is only one peak in the ρ-T curve of the sample with x=0.15.
The second-order combination Raman modes of bilayer graphene in the range of 1800-2150 cm-1
Authors: Li Qiao-Qiao  , Zhang Xin  , Wu Jiang-Bin  , Lu Yan  , Tan Ping-Heng  , Feng Zhi-Hong  , Li Jia  , Wei Cui  , Liu Qing-Bin  ,   State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China;,   Science and Technology on ASIC Laboratory, Hebei Semiconductor Research Institute, Shijiazhuang 050051, China
Published: December 2020

In this paper, Raman modes of bi-layer graphene are investigated in detail in the frequency region between 1800 and 2150 cm-1. There are four dominant Raman modes in this frequency region. The frequencies of these modes dependent on excitation energy are revealed from the measurement with multi-wavelength lasers, which can be fully understood based on double resonance Raman scattering and the phonon dispersion relation of monolayer graphene. The results show that these Raman modes can be assigned to the combinational modes from the fundamental modes of iTA, LA and LO phonons, but not from iTO and oTO phonons as reported in the previous works. This study benefits us toward the full understanding of lattice dynamics of monolayer and multilayer graphenes.
Predictive reliability of summer precipitation in China based on error distribution of numerical model
Authors: Yang Jie  , Gong Zhi-Qiang  , Zhao Jun-Hu  , Xu Xia-Zhen  ,   Jiangsu Climate Center, Jiangsu Meteorological Administration, Nanjing 210000, China;,   National Climate Center, China Meteorological Administration, Beijing 100081, China
Published: December 2020

In this paper, we made some statistical analyses on precipitation prediction errors of coupled global climate model of National Climate Center based on CPC merged analysis of precipitation. Through the statistics of the forecast results of summer precipitation in many years and the errors, we find that the distribution of the model prediction errors satisfies the Gaussian distribution. Based on the Gaussian distribution characteristics, the ability to predict the mode for summer precipitation in China can be analyzed and compared. The forecast performance of the dynamic-statistics scheme is significantly better than that of system error correction scheme of the model. The dynamic-statistics optimal combination of factor revise is corrected, relative to error distribution pattern of the system revised forecast, and there are obtained two kinds of error distribution characteristics: 1) improvement of the amplitude; 2) improvement of the displacement. Based on the statistical characteristics of the prediction error, measure of the credibility of model forecast results is proposed to quantitatively assess the credibility of the numerical model forecast results in different regions. Taking the summer precipitations in 2012 and 2013 for example, we analyze the credibility of actual observations, prediction and drought or flood level. Comparing actual observations and prediction, we find that there is a good consistency where the credibility of them is larger, while there are many bad predictions in the region where the credibility of them is smaller. What is more, compared with other reliability test method, the credibility of the abnormal precipitation forecast by this method is more accurate, showing the effectiveness of the method.
Studies on weighted scale-free topology in energy heterogeneous wireless sensor network
Authors: Han Li  , Liu Bin  , Li Ya-Qian  , Zhao Lei-Jing  ,   Institute of Information Science and Engineering, Yanshan University, Qinhuangdao 066004, China;,   The Key Laboratory for Special Fiber and Fiber Sensor of Hebei Province, Yanshan University, Qinhuangdao 066004, China
Published: December 2020

In view of the problems about imbalance of node energy consumption and obtaining the load of node or edge efficiently in wireless sensor network, a kind of weighted scale-free topological evolution model for energy heterogeneity is put forward within the scope of local areas. By modelling the relationship among the node energy, load, energy consumption, and the weight to node and edge, we then give the evolution of the network through combining node weight and weighted model, deduce the power-law distribution of the node weight, the edge weight, and node degree, respectively, and next analyze the load and energy consumption according to the node weight and edge weight. Simulation results show that the proposed model not only can make accurate calculation for node and edge loads, but also can alleviate the node energy consumption imbalance in scale-free network.
Study on phase-shift control in dispersion decreasing fibers
Authors: Sun Qing-Hua  , Pan Nan  , Lei Ming  , Liu Wen-Jun  ,   Beijing Union University, College of Mechanical and Electrical Engineering, Beijing 100020, China;,   School of Science, P. O. Box 122, Beijing University of Posts and Telecommunications, Beijing 100876, China;,   Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
Published: December 2020

Phase-shift control can effectively avoid soliton interactions. With symbolic computation and Hirota's bilinear method, analytic studies are made on nonlinear Schrdinger equation, which can be used to describe the propagation of solitons in dispersion decreasing fibers. Analytic two-soliton solutions are obtained. With the obtained solutions, when the variable group-velocity dispersion function of dispersion decreasing fibers is a Gaussian one, the phase-shift control is achieved, soliton interactions are avoided, and the pulse quality in optical communication systems can be improved. Moreover, influences of parameters in dispersion decreasing fibers on the phase-shift control are discussed. Results are also helpful for the logic gates and optical switches.
Synchronizing a class of uncertain and variable time-delay fractional-order hyper-chaotic systems by adaptive sliding robust mode control
Authors: Wu Xue-Li  , Liu Jie  , Zhang Jian-Hua  , Wang Ying  ,   Department of Electrical Engineering, Hebei University of Science and Technology, Shijiazhuang 050000, China
Published: December 2020

In view of a class of synchronization problems about uncertain and variable time-delay systems, this paper puts forward a method of adaptive sliding robust control. Based on the Lyapunov stability theory and adaptive sliding mode control methods, the adaptive sliding robust controllers and the parameter adaptive rate are designed. A single controller designed by the synchronous control method is applicable to the synchronizing of a class of fractional-order hyper-chaotic systems, and it has a great ability to resist noise-perturbed. What is more, it can also well control the time-varying time-delay systems. So the controller is of highly practical value. Furthermore, by introducing a certain amount of compensation into the system, the influences of the uncertainty and the noise-disturbance can be eliminated, thus the synchronization of the uncertainty fractional-order hyper-chaotic system is realized. In addition, the control of the synchronous errors of the systems can be stable in arbitrarily small domain. Finally, time-varying and time-delay fractional-order Chen's hyper-chaotic systems with the external noisy disturbances and uncertain parameters are numerically simulated, and the effectiveness of the proposed control method is verified.
X-ray spectrum emitted by the impact of 129Xe26+ of the different kinetic energies on Au surface
Authors: Liang Chang-Hui  , Zhang Xiao-An  , Li Yao-Zong  , Zhao Yong-Tao  , Xiao Guo-Qing  ,   Ion Beam and Optical Physical Laboratory, Xianyang Normal University, Xianyang 712000, China;,   Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China
Published: December 2020

The characteristic X-ray spectra produced by the impact of 129Xe26+ with kinetic energies from 350 to 600 keV and from 1.8 to 3.9 MeV on Au surface are measured. It is found that 129Xe26+ with kinetic energies from 350 to 600 keV can excite only the characteristic X-ray spectra of Mα of Au, but 129Xe26+ with kinetic energies from 1.8 to 3.9 MeV can excite the characteristic X-ray spectra of Mζ, Mα, Mγ and Mδ. The relation between the characteristic X-ray intensity, the ratio of X-ray yield and the ion kinetic energy is analyzed. The kinetic energy threshold of L-X-ray of Xe emitted by Xe26+ is estimated.
Density functional theory study of structure characteristics and stabilities of Al2Sn(n=2-10) clusters
Authors: Lü Jin  , Yang Li-Jun  , Wang Yan-Fang  , Ma Wen-Jin  ,   School of Chemistry and Material Science, Shanxi Normal University, Linfen 041004, China
Published: December 2020

The geometric configurations and electronic structures of the Al2Sn (n=2-10) clusters are calculated by the B3LYP (density functional theory) method at 6-311G** level. The variations of the ground state structure, charge transfer and bonding characteristic of the aluminum-sulfur doped clusters are discussed in detail. The results show that the structures of pure Sn clusters are fundamentally changed due to the doping of the Al atoms. Our work exhibits that the all the ground states of Al2Sn clusters share the same four-member Al2S2 ring, and from single ring to three rings plane and three-dimensional structure structures are formed by inserting one S atom or S clusters. The stability of cluster structure is influenced by both the chemical bond structure and number. The stability information of Al2Sn clusters is obtained by analyzing the dissociation energies and the second-order difference energies of the ground state structures.
Modeling and electromagnetic scattering from the overturning wave crest
Authors: Li Wen-Long  , Guo Li-Xin  , Meng Xiao  , Liu Wei  ,   School of Physics and Optoelectronic Engineering, Xidian University, Xi'an 710071, China
Published: December 2020

The presence of sea spikes can cause the radar false alarm probability rise and performance degradation of multi-target environment detection. Therefore, study of the phenomenon of sea spikes is of great significance. HH polarization scattering intensity close to or even greater than the VV polarization scattering intensity is an important feature of sea spike phenomenon. Overturning wave crest is considered to be one of the reasons of generating sea spike. In this paper, overturning wave crest model is introduced with the consideration of the wind speed, and the method of moment is used for studying HH and VV backward scattering coefficient for different incident frequencies, incident angles, wind speeds, and wind directions. It is found that super phenomenon (HH scattering intensity is greater than VV polarization scattering intensity) is more obvious in the cases of low grazing and large wind speed, thus it is deduced that the sea spike phenomenon occurs with a high probability in the case of low grazing angle. Moreover, the distributions of sea clutter amplitude and Doppler spectra are also examined for the overturning wave crest model with low grazing incidence.
Ptychographical imaging algorithm based on illuminating beam matched with rotationalphase encoding
Authors: Wang Zhi-Hao  , Wang Ya-Li  , Li Tuo  , Shi Yi-Shi  ,   University of Chinese Academy of Sciences, Beijing 100049, China;,   Academy of Opto-Electronics, Chinese Academy of Sciences, Beijing 100094, China;,   State Key Laboratory of Information Security, Institute of Information Engineering, Chinese Academy of Sciences, Beijing 100093, China
Published: December 2020

We propose a new ptychographical imaging algorithm based on illuminating beam cooperating with rotational phase encoding. Compared with the traditional ptychographical imaging, the proposed algorithm has a diffractive wave front that is encoded with the uniform phase modulator in a block. It leads to the faster convergent speed for the iterative algorithm of the ptychographical imaging. The illuminating method can present fantastic robustness to resist bad influences brought by the noise and transverse shift of probes. Compared with the random phase modulator, the rotated phase modulator introduced into our algorithm is convenient to be fabricated and located into the real configuration. Therefore, the proposed algorithm has a good value in practical applications such as real-time microscopy and superresolution imaging.
Electronic structures and phase instabilities of cubic Na1/2Bi1/2TiO3 and K1/2Bi1/2TiO3： a first-principles comparative study
Authors: Zhou Shu-Lan  , Zhao Xian  , Jiang Xiang-Ping  , Han Xiao-Dong  ,   Department of Material Science and Engineering, Jingdezhen Ceramics Institute, Jingdezhen 333403, China;,   State Key Laboratory of Crystal Material, Institute of Crystal Material, Shandong University, Jinan 250100, China
Published: December 2020

The electronic structures, potential energy surfaces for the displacement of ions along the tetragonal [001] and Γ phonon properties of Na1/2Bi1/2TiO3 and K1/2Bi1/2TiO3 are investigated by employing the first-principles method based on density functional theory. The results indicate that the electronic structures of Na1/2Bi1/2TiO3 and K1/2Bi1/2TiO3 are very similar. The valence band is dominated by O 2p states with an admixture of Ti 3d and Bi 6p states. The lower energy region of the conduction band is mainly composed of Ti 3d orbitals. The bond strengths of Ti–O and Bi–O increase when Na is substituted by K. Moreover, minor differences are observed from the potential energy surface for the displacement of ions along the tetragonal [001], which indicates that the phase instabilities of the two compounds mainly come from the displacement of O ions, which plays a more important role when Na is substituted by K. There are three soft modes for Na1/2Bi1/2TiO3 and K1/2Bi1/2TiO3, which mainly originate from the vibration of O6 group. The A2u soft mode becomes harder when Na is substituted by K.
Multipactor phenomenon between metal anddielectric window
Authors: Zhang Xue  , Wang Yong  , Fan Jun-Jie  , Zhu Fang  , Zhang Rui  ,   Key Laboratory of High Power Microwave Sources and Technologies, Institute of Electronics, Chinese Academy of Sciences, Beijing 100190, China;,   University of Chinese Academy of Sciences, Beijing 100149, China
Published: December 2020

The multipactor phenomenon between metal wall and dielectric window disk of pill-box window can behave as double surface multipactor, which is affected by the normal electric field of TM11 mode. The Monte Carlo code is used to build up simulation model, calculate the multipactor susceptive curve, threshold voltage, evolution of particle number, and the trajectory of particle motion under the action of double surface normal field between alumina window and copper wall. Through investigating the behavior of secondary electrons, the regularity of normal field double surface resonant multipactor and non-resonant multiapctor is achieved. Besides, the feature of the transform from double-surface multipactor to single-surface multipactor is also obtained. This research can provide a theoretical basis for window breakdown mechanism analysis.
van der Waals heterostructure about CuPc/MoS2(0001)
Authors: Cao Ning-Tong  , Zhang Lei  , Lü Lu  , Xie Hai-Peng  , Huang Han  , Niu Dong-Mei  , Gao Yong-Li  ,   Institute of Super-Microstructure and Ultrafast Process in Advanced Materials, Central South University, Changsha 410083, China;,   Department of Physics and Astronomy, University of Rochester, Rochester 14627, USA
Published: December 2020

Molecular packing and interfacial electronic properties of well-ordered organic semiconductor, copper phthalocyanine, thin films grown on MoS2(0001) are studied with low energy electron diffraction (LEED) optics, atomic force microscope (AFM) and photoelectron spectroscopy (PES). The band structure of MoS2(0001) around the Γ point of the surface Brillouin zone is given by angle-resolved photoelectron spectroscopy. The LEED patterns indicate that three equivalent well-ordered two-dimensional square lattices are formed in CuPc monolayer thin film along three surface crystalline axes ([1120], [1210] and [2110]) of MoS2 (0001) substrate, respectively. The AFM measurements show that the growth of CuPc on MoS2 (0001) occurs in a Stranski-Krastanov mode. The CuPc molecule can be flat-laying on MoS2(0001) at low coverage (～0.3 nm), but form strip-like crystals along the surface crystal axes of MoS2 (0001) at high coverage (>2.4 nm). The CuPc molecule shows obvious anisotropy, indicating that the molecular plane is not parallel to the MoS2 surface. The PES measurements show there is no charge transfer process at the interface, indicating weak van der Waals interaction between CuPc and MoS2(0001).
Influences of the substrate position on the morphology and characterization of phosphorus doped ZnO nanomaterial
Authors: Feng Qiu-Ju  , Xu Rui-Zhuo  , Guo Hui-Ying  , Xu Kun  , Li Rong  , Tao Peng-Cheng  , Liang Hong-Wei  , Liu Jia-Yuan  , Mei Yi-Ying  ,   School of Physics and Electronic Technology, Liaoning Normal University, Dalian 116029, China;,   Preparatory Department, School of Science, Dalian Nationalities University, Dalian 116600, China;,   School of Physics and Optoelectronic Engineering, Dalian University of Technology, Dalian 116024, China
Published: December 2020

One-dimensional phosphorus doped ZnO nanowires and nanonails are prepared on Si substrate without employing any metal catalyst by chemical vapor deposition method. Field-emission scanning electron microscopy shows that the samples located downstream 1.5 cm away from the source material are of nanowire structure and located 1 cm above source materials of nanonail structure, and the growth mechanisms of phosphorus doped ZnO nanostructures with different morphologies are discussed. The photoluminescence properties of phosphorus doped ZnO nanowires and nanonails are studied at a temperature of 10 K. The phosphorus related acceptor emissions are observed. Furthermore, the current-voltage (I-V) measurement based on the ZnO nanostructures/Si heterojunctions shows a typical semiconductor rectification characteristic with positive open electric fields being 4.8 and 3.2 V, respectively.