bluuebunny/crossref_metadata_2025 huggingface dataset:
Molecular dynamics simulation of resonance properties of strain graphene nanoribbons
Authors: Gu Fang  , Zhang Jia-Hong  , Yang Li-Juan  , Gu Bin  ,   (1)College of Electronic & Information Engineering, Nanjing University of Information Science & Technology, Nanjing 210044, China; (2)College of Math & Physics, Nanjing University of Information Science & Technology, Nanjing 210044, China; (3)Department of Basic Courses, Suqian College, Suqian 223800, China
Published: December 2020

Starting from the energy conversion and energy conservation law in the constant-NVE ensemble, the molecular dynamics method using the COMPASS force field was applied to investigate the dynamic properties of graphene nanoribbons (GNRs) together with the GNR-based strain sensors. The following results were obtained: (a) the nonlinear response dominates the dynamic behavior of GNRs, and their ultra-high fundamental frequencies are closely related with the length and boundary conditions; (b) the effect of uniaxial tensile strain on the fundamental frequencies of GNRs is significant and strongly depends on boundary conditions, and the GNR-based strain sensor clamped on four edges has a higher frequency shift, and its sensitivity is up to 7800 Hz / nanostrain, much higher than that of carbon nanotube-based strain sensor with the same length; (c) the resonant characteristics of GNRs and GNR-based strain sensors are insensitive to the chirality. The obtained results suggest that, through cutting the appropriate size and setting the boundary conditions, the GNRs could be used to design a new generation of nanoelectromechanical system (NEMS) resonators and strain sensors, owing to their ultra-low density and ultra-high fundamental frequencies as well as ultra-high sensitivity without considering the impact of chirality.
Three-dimensional simulation of total dose effects on ultra-deep submicron devices
Authors: He Bao-Ping  , Ding Li-Li  , Yao Zhi-Bin  , Xiao Zhi-Gang  , Huang Shao-Yan  , Wang Zu-Jun  ,   Northwest Institute of Nuclear Technology, Xi'an 710613, China
Published: December 2020

The radiation-induced charge distribution in shallow-trench isolation (STI) structures is analyzed in this paper. We present a new approach for modeling total dose effect of ultra-deep submicron transistors. The results show that, when there is no radiation-induced charge in top100 nm of the trench-silicon interface, the simulation results of 0.18μm ultra-deep submicron transistors show that the I-V sub-threshold does not produce the hump, and yield good agreement with experiments. On the aspect of the improvement on total ionizing dose, the leakage current of MOSFET with delta doping can be effectively reduced than with the uniform doping profile under lower radiation dose. If the Halo doping is adopted in landscape orientation, the total dose of ultra-deep submicron transistors can be improved. This improvement is evident even at higher irradiation dose.
Study on fractal features of modulated radio signal
Authors: Yang Xiao-Niu  , Li Jian-Dong  , Tang Zhi-Ling  ,   (1)School of Communications Engineering, Xidian University, Xi'an 710071, China; (2)School of Communications Engineering, Xidian University, Xi'an 710071, China; School of Electronic Engineering, Guilin University of Electronic Technology, Guilin 541004, China; (3)Science and Technology on Communication Information Security Control Laboratory, Jiaxing 314033, China
Published: December 2020

The shape of radio signals determined by modulation system and that produced by the nonlinear transform are different in kind, which is the basis for discriminating them. Feature extraction based on fractal theory is a new method. In this paper,the features of modulation and nonlinear transform are projected to fractal feature space by computing the variance fractal dimension and the Mandelbrot singularity spectra dimensions. The numerical result show that differences in fractal features do exist between different modulated signals and the nonlinear transformed signals. The results show that the feature of these signals can be extracted based on fractal theory, which has engineering value for the identification of modulated radio signals.
Relationship between liquid structure and property Ⅱ—— Kinematic viscosity of Mg-9Al melt and its relationship with the microstructure
Authors: Сабирзянов А А  , Попель П С  , Mi Guang-Bao  , Li Pei-Jie  , Охапкин А В  , Константинова Н Ю  ,   (1)National Center of Novel Materials for International Research, Tsinghua University, Beijing 100084, China; (2)Научно-исследовательскый центр "Расплав", Уральский Государственный Педагогический Университет, Екатеринбург 620017, Россия
Published: December 2020

The method of crucible rotating oscillation damping is employed to measure the kinematic viscosity of Mg-9Al melt, and the curve of viscosity ν versus temperature T from 890 K to 1190 K is obtained. It is found that there is an abnormal change for the viscosity in the first heating process, i.e., when the temperature is increased to 1000—1075 K, the viscosity varies from increase to decrease. However, in the subsequent cooling process and the second heating process, the viscosity increases (decreases) monotonically according to an exponential law with temperature, which accords with the Arrhenius equation. Based on the residual bond model and the calculation model for evolution behavior of "average atomic cluster", the correlation between viscosity and microstructure of Mg-9Al melt is discussed. The results show that the breakage of Al-Al(B) bonds in basic unit of β phase-like residual bond structures causes an abnormal change of viscosity in the first heating process; in the subsequent cooling process and the second heating process, the melt reaches a new dynamic equilibrium state, and Al atoms are uniformly distributed in the melt. At this time, the size of Mg-Al average atomic cluster dS and the number of short-range order atoms NS inside them increase (decrease) monotonically with temperature, and the relationship between viscosity ν and size of average atomic clusters dS is expressed as a linear function, i.e., ν = ν0 + K·dS, which presents a new way for revealing micro-structure change of alloy melt and further understanding the change characteristic of viscosity.
Evolution of interphase misfit dislocation networks in Ni-based single crystal superalloy under shear loading
Authors: Wu Wen-Ping  , Guo Ya-Fang  , Wang Yue-Sheng  , Xu Shuang  ,   Department of Engineering Mechanics, Beijing Jiaotong University, Beijing 100044, China
Published: December 2020

The molecular dynamics simulation is used to study the evolution of misfit dislocation networks at γ/γ' phase interfaces of Ni-based single crystal superalloy under shear loading. From the simulation we found that the three patterns of dislocation networks on the (100), (110) and (111) phase interfaces show different degrees and patterns of damage. The deformation and damage occur easier at a higher temperature. Under the same shear loading and temperature, the square dislocation network at (100) phase interface is the most stable.
The laser induced electronic acceleration process in nanostructured dielectric
Authors: Xia Zhi-Lin  ,   School of Materials Science and Engineering, Wuhan University of Technology, Wuhan 430070,China; Low Dimensional Materials & Application Technology, Xiangtan University, Xiangtan 411105,China
Published: December 2020

The Monte Carlo method has been used to simulate the process of electron transport and acceleration in a nano-dimensional unit when irradiated by laser pulse of wavelength 1064 nm and power density of GW/cm2 level. When electrons transport in laser field, the scattering of electron-phonon and electron-surface are considered. The results show that: when the size of simulation unit is small to a degree, electron-surface scattering will dominate the scattering process and the small size effect becomes obvious. As a result, the electron is difficult to absorb laser energy. Based on the results, we can design new kind of films with nanostructure and improve the laser induced damage threshold of optical films.
Ab initio calculation of pressure-induced phase transition of TiN polytypes
Authors: Gu Xiong  , Gao Shang-Peng  ,   Department of Materials Science, Fudan University, Shanghai 200433, China
Published: December 2020

Based on a plane wave pseudopotential method within the framework of density functional theory, equilibrium structure, bulk modulus, and relative stability were calculated for 6 kinds of TiN polytypes including B1 (NaCl structure), B2 (CsCl structure), B3 (zincblende structure), Bk (hexagonal BN structure), Bh (WC structure) and B81 (NiAs structure). Theoretical calculation also showed that TiN can not exist in B4 (wurtizite) structure. Through geometry optimization under hydrostatic pressure, the enthalpy of each TiN phase at different pressures was obtained. It was found that TiN with B1 structure is the most stable phase at pressure lower than about 345 GPa, whereas B2 TiN is the most stable at pressure above 345 GPa. Volume discontinuity and bulk modulus change can be observed during the transition from B1 to B2 phase.
Nonclassical ground state for Fröhlich palaron
Authors: Luo Zhi-Hua  , Yu Chao-Fan  , Lin Qia-Wu  ,   Department of Physics, Guangdong University of Education, Guangzhou 510303, China
Published: December 2020

Based on the variational approach proposed by Huybrecht , using the two-mode squeezed coherent state as the second-step canonical transformation, we have investigated the nonclassical ground state for the Fröhlich polaron through considering the dynamical correlation bewteen the phonon wave vectors q and q' . Due to the correlation effect between the phonon coherent state and the phonon squcezed state, caused by the two-mode squeezing effect of the phonon coherent state, the coherent parameter fq and the two-mode squeezing angle φqq' also have a big correction correspondingly. As a result , this effect has greatly enhanced the coherent effect and the squeezing angle effect . The calculation and the analysis based on the ground state energy of the polaron have shown that 1) for the weakly coupled region ,the correction ΔE(1)c due to the effect of the displaced-phonon squcezed state is comparable to the Feynma n' s path integral calculation (ΔEf) and the coherent state correetion by Huybrechts (ΔE0), while the correction (ΔE(2)c) due to the squeezing effect of the phonon coherent state has an essential contribution , i.e. ΔE(2)c«(ΔEf,ΔE0); 2) for the strongly-coupled region ,the contribution from the displaced-phonon squcezed state has a greatly reduction , ΔE(1)c≥(ΔEf,ΔE0) .Althougth, at the same time ,the contribution due to the squeezing effect of the phonon coherent state also has a greatly reduction ,we still have ΔE(2)c«(ΔEf,ΔE0).
Study of crystalline structure change of annealing-induced self-organization in polymer field-effect transistors
Authors: Jia Quan-Jie  , Chen Yu  , Tian Xue-Yan  , Yao Jiang-Feng  , Zhao Su-Ling  , Gong Wei  , Fan Xing  , Xu Zheng  , Zhang Fu-Jun  ,   (1)Beijing Asahi Glass Electronics co., Ltd. Beijing 100016,China; (2)Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049,China; (3)Institute of Optoelectronics Technology, Beijing Jiaotong University, Key Laboratory of Luminescence and Optical Information (Beijing Jiaotong University), Ministry of Education, Beijing 100044, China
Published: December 2020

With the aim of understanding the relationships between polymer self-organization and charge carrier mobility of polymer organic field-effect transistor (OFET), we investigate crystalline microstructure change of annealing-induced self-organization of regioregular poly(3-hexylthiophene) (RR-P3HT) active thin layer in polymer OFET by synchrotron radiation grazing incident X-ray diffraction (GIXRD). The crystalline microstructures of RR-P3HT thin film with different preparation methods (spin-coating and drop-casting) and different concentrations (2.5 mg/ml and 3.5 mg/ml) at various annealing temperatures are studied. These results present that, the crystalline structures of RR-P3HT active layers annealed at 150 ℃ are better and enhanced to charge transport, which tend to pack form the thiophene rings are perpendicular and the π-π interchain stacking parallel to the substrate. Furthermore, we find that an appropriate annealing temperature can facilitate the crystal structure of edge-on form, resulting in field-effect mobility enhancement of polymer OFET.
Electrical properties of the metal/porous silicon/Si(M/PS/Si) microstructure
Authors: Sun Peng  , Hu Ming  , Liu Bo  , Sun Feng-Yun  , Xu Lu-Jia  ,   School of Electronic Information Engineering, Tianjin University, Tianjin 300072, China
Published: December 2020

In this paper, porous silicon (PS) was prepared in a double-tank cell using the electrochemical corrosion method. Subsequently, different metal films for electrical contacts were deposited on the PS samples by magnetron sputtering to form the M/PS/Si microstructure. The PS surface morphology was characterized by SEM. The electrical properties of the M/PS/Si microstructure were studied through the I-V characteristic tests. It was shown that Pt can form ohmic contact with PS. The I-V characteristic curves were formed from two parts:linear part and nonlinear part. However, Cu formed Schottky contact with PS and its I-V curves showed rectification characteristics. The rectification ratio decreased when the porosity of the PS increased.
Electronic density distribution of La0.55Ca0.45MnO3 revealed by temperature-dependent X-ray diffraction
Authors: Yue Ting  , He Hao  , Zhang Xing  , Li Guang  ,   (1)School of Physics and Materials Science, Anhui University, Hefei 230039, China; (2)School of Physics and Materials Science, Anhui University, Hefei 230039, China; Anhui Key Laboratory of Information Materials and Devices, Hefei 230039, China
Published: December 2020

The temperature-dependent spatial structure of perovskite oxide La0.55Ca0.45MnO3 has been checked by X-ray diffraction (XRD) and Rietveld method was employed to refine the XRD data. It was found that with the decrease of temperature, almost all of the diffraction peaks were split; each peak was divided from single peak at high temperature into two peaks at low temperature, indicating the appearance of a crystalline structural phase transition. Corresponding to the structural phase transition, magnetization measurements also revealed a magnetic transition from ferromagnetism to antiferromagnetism. With the Rietica analysis of the XRD data of the compound, plots of the electronic density distribution of La0.55Ca0.45MnO3 were made. Sharp difference in the distributions above and below the transition temperature was clearly shown. Taking the magnetism of the compound into consideration, the structural phase transition was analyzed and the sharp difference of the electronic density distribution was qualitatively explained.
Study on resonance magnetoelectric effect of layeredNi/Pb(Zr,Ti)O3/TbFe2 composites
Authors: Bi Ke  , Ai Qian-Wei  , Yang Lu  , Wu Wei  , Wang Yin-Gang  ,   College of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China
Published: December 2020

Layered magnetoelectric Ni/PZT/TbFe2 composites have been prepared by electroless deposition and bonding method. The influence of the Ni layer thickness on ME coupling and resonance frequency is discussed. The results show that the magnetoelectric coefficient of Ni/PZT/TbFe2 composites changes differently from that of other composites and two remarkable resonance peaks have been observed. The magnetoelectric voltage coefficient at the first-order longitudinal resonance mode increases as the Ni layer thickness increases. Both experimental and calculated data reveal that the first-order bending resonance frequency fr1 and longitudinal resonance frequency fr2 increase with the Ni layer thickness.
Theoretical study and numerical verification of terahertz radiation emitted by carbon nanotubes
Authors: Le Li-Wei  , Wang Yan  , Wang Yue  , Wu Yu-Ming  , Fu Jia-Hui  , Wang Dong-Xing  , Wu Qun  ,   Department of Electrical and Computer Engineering, National University of Singapore 119260, Singapore;,   Department of Electrical Science and Technology, Key Laboratory of Engineering Dielectrics and Its Application, Ministry of Education, Harbin University of Science and Technology, Harbin 150080, China;,   Department of Electrical Science and Technology, Key Laboratory of Engineering Dielectrics and Its Application, Ministry of Education, Harbin University of Science and Technology, Harbin 150080, China; State Key Lahoratory of Millimeter Wave, Nanjing 2100;,   School of Electronics and Information Technology, Harbin Institute of Technology, Harbin 150001, China;,   School of Electronics and Information Technology, Harbin Institute of Technology, Harbin 150001, China; Department of Electrical Science and Technology, Key Laboratory of Engineering Dielectrics and Its Application, Ministry of Education, Harbin Universit;,   School of Electronics and Information Technology, Harbin Institute of Technology, Harbin 150001, China; State Key Lahoratory of Millimeter Wave, Nanjing 210096, China
Published: December 2020

Based on the theory of simple tight-binding, the electronic energy structure of carbon nanotubes has been obtained under the quantitative periodic boundary condition of the carbon nanotubes. Terahertz radiation emitted by carbon nanotubes was demonstrated theoretically by adopting the reported experimental results of the interaction between electron and phonon. The numerical results verify that the carbon nanotubs can generate terahertz radiation and the reason of the terahertz oscillation was analyzed. All results provide a sound theoretical basis for using carbon nanotubes to generate terahertz wave in the experiments.
Study of spectral response for transmission-modeNEA GaN photocathodes
Authors: Du Xiao-Qing  , Wang Xiao-Hui  , Chang Ben-Kang  , Qian Yun-Sheng  , Gao Pin  , Zhang Yi-Jun  , Qiao Jian-Liang  ,   (1)College of Optoelectronic Engineering,Chongqing University,Chongqing 400030,China; (2)Institute of Electronic Engineering and Optoelectronic Technology,Nanjing University of Science & Technology,Nanjing 210094,China
Published: December 2020

Transmission-mode GaN photocathodes with the emission layer thickness of 150 nm and the doping concentration of 1.6×1017 cm-3 were grown by metal-organic chemical vapor deposition (MOCVD) and were activated in ultra-high vacuum system. The result was tested by Multi-information test system. The shape of transmission-mode NEA GaN photocathode quantum yield curves looks like the Chinese charocter 门 for "door", the photocathode had flat and high response between 255 and 355 nm, the highest quantum yield of 13% appeared at 290 nm. When the wavelength was less than 255 nm the quantum yield was decreased because of the high absorption coefficient of AlN buffer layer at short wavelengths. The quantum yield was also decreased beyond 355 nm and fell to 3.5% at the threshold of 365 nm, the quantum yield at 385 nm was reduced to 0.1% and the cut-off character of long wave was well shown. The quantum yield formula of transmission-mode GaN photocathode has been solved from diffusion equations, and the main factors affecting the quantum yield mostly, including electron diffusion length, electron escape probability, active-layer thickness and the back-interface recombination velocity, were analysed and discussed. The future work is optimizing the structure of the photocathodes.
Modeling of regular eutectic growth of binary alloy basedon cellular automaton method
Authors: Wu Meng-Wu  , Xiong Shou-Mei  ,   State Key Laboratory of Automobile Safety and Energy, Department of Mechanical Engineering,Tsinghua University, Beijing 100084, China
Published: December 2020

Based on cellular automaton method, a numerical model was developed for the regular eutectic growth of binary alloy. By coupling with the macro-temperature field and considering the solute diffusion, the constitutional undercooling and the curvature undercooling, modeling of the steady-state lamellar eutectic growth was achieved. A systematic investigation on eutectic growth morphology and lamellar spacing of a model alloy was made under unidirectional solidification conditions with different undercoolings, initial lamellar spacings, temperature gradients and solidification rates. The results reproduced the adjustment of lamellar spacing of two eutectic phases under the interaction between solute diffusion and surface energy by mechanisms of nucleation, lamellar branching, lamellar termination and overgrowth. The simulated results were in agreement with those predicted by the Jackson-Hunt model and experimental results by other researchers. Finally, the model was extended to three dimensional systems, which verified its feasibility of modeling the three-dimensional eutectic growth.
Investigation of electrochemical performances of ZnFe2O4 prepared by solid state and hydrothermal method
Authors: Bai Ying  , Ding Ling-Hong  , Zhang Wei-Feng  ,   Key Laboratory of Photovoltaic Materials of Henan Province and School of Physics & Electronics, Henan University, Kaifeng 475004, China
Published: December 2020

Spinel structure ZnFe2O4 were prepared by solid state reaction and hydrothermal method. Investigations on X-ray diffraction (XRD), scanning electron microscopy (SEM) and specific area measuements indicate that the samples are well-crystallized cubic spinel structre with average particle sizes of 500 nm and 200 nm and specific areas of 136.7 m2 g-1 and 382.5 m2 g-1 for solid state reaction and hydrothermal method, respectively. The ZnFe2O4 samples show high lithium-storage capacity and good reversibility. Compared with the sample prepared by solid state reaction, ZnFe2O4 prepared by hydrothermal method demonstrate better electrochemical performances. Its specific charge capacity decays from 750 mAh g-1 to 702 mAh g-1 after 30 cycles, with capacity retention of 93.6 %. ZnFe2O4 is a very promising anode material for lithium ion battery for its easy preparation, low coat and good electrochemical performances.
A two-dimensional subthreshold current model for fullydepleted strained-SOI MOSFET
Authors: Qin Shan-Shan  , Zhang He-Ming  , Hu Hui-Yong  , Qu Jiang-Tao  , Wang Guan-Yu  , Xiao Qing  , Shu Yu  ,   Key Laboratory of Ministry of Education for Wide Band-Gap Semiconductor Materials and Devices,School of Microelectronics, Xidian University, Xi'an 710071, China
Published: December 2020

An analytical model for the subthreshold current of fully depleted strained -SOI MOSFET was developed by solving the two-dimensional (2D) Poisson equation and the conventional drift-diffusion theory. Model verification was carried out using the 2D device simulator ISE. Good agreement was obtained between the model's calculations and the simulated results. By analyzing the model, the dependence of current on the strained Si layer strain, thickness and doping was studied. This subthreshold current model provides valuable reference to the FD-SSOI MOSFET design.
Inserting various cathodic buffer layers to enhancethe performance of Pentacene/C60based organic solar cells
Authors: Liu Rui  , Xu Zheng  , Zhao Su-Ling  , Zhang Fu-Jun  , Cao Xiao-Ning  , Kong Chao  , Cao Wen-Zhe  , Gong Wei  ,   Key Laboratory of Luminescence and Optical Information, Beijing Jiaotong University, Ministry of Education, Institute of Optoelectronics Technology, Beijing Jiaotong University, Beijing 100044, China;,   Key Laboratory of Luminescence and Optical Information, Beijing Jiaotong University, Ministry of Education, Institute of Optoelectronics Technology, Beijing Jiaotong University, Beijing 100044, China; Yulin Ploytechnic (Shenmu Campus), Shenmu Vocational E;,   Key Laboratory Solar Thermal Energy and Photovoltaic Systems, Institute of Electrical Engineering,Chinese Academy of Sciences, Beijing 100190, China
Published: December 2020

Devices with the structure of ITO/Pentacene/C60/Al were prepared. Then, in order to enhance the performance of these cells and study the mechanism of the cathodic buffer layer, bathocuproine (BCP) of different thickness were inserted between C60 and Al. When inserting 10 nm BCP, the power conversion effciency of the cell is as high as 0.46%. On this basis, bathophenanthroline (Bphen) and 3, 4, 9, 10-Perylenetetracarb-oxylicdianhydride (PTCDA) are used instead of BCP, so as to compare and discuss the effects on the performance of the solar cells caused by the electron mobility and optical absorption properties of the cathodic buffer layers. As the electron mobility of Bphen is two orders of magnitude higher than that of BCP, the efficiency of devices with Bphen as the buffer layer was improved to 0.56%. Furthermore, the absorption spectrum of devices was obviously enhanced by inserting PTCDA material which has large absorption in visible light region, and the highest current density of such device was enhanced to 5.97 mA/cm2 and the efficiency was 0.87%.
Network statistical analysis in peer-to-peer application
Authors: Ren Yong  , Yuan Jian  , Wang Yue  , Shan Xiu-Ming  , Li Yi-Peng  , Huang Xiao-Hong  ,   (1)Department of Electronic Engineering, Tsinghua University, Beijing 100084, China; (2)Institute of Networking Technology, Beijing University of Posts and Telecommunications, Beijing 100876, China
Published: December 2020

The rich statistical characteristics in peer-to-peer (p2p) network have recently attracted much research interest. This paper reveals the internal network statistical characteristics in the user network and resource network, both of which are abstracted from the real application downloading logs. The two-segment degree and weight distribution of user nodes indicate the dynamic of p2p users, and the similar power-law distribution of resource nodes shows the popularity diversity. Furthermore, we found that these two networks have the inherent cluster structure, only minority of clusters contain a large number of nodes, and the majority have fewer nodes in it. In user network, users in the same cluster have similar file-sharing interest, in contrast to the different user interest between clusters; meanwhile, there are obvious correlations between different resource categories in resource clusters.
The influence of U-turn movement on the dynamics of traffic flow
Authors: Guo Hong-Wei  , Gao Zi-You  , Xie Dong-Fan  ,   School of Traffic and Transportation, Beijing Jiaotong University, Beijing 100044, China
Published: December 2020

U-turn movement is a common form of traffic organization in urban streets. A traffic flow model for U-turn movement based on the NaSch cellular automaton model is proposed to simulate and analyze the dynamics of U-turn movement. The results indicated that the U-turn movement has significant effect on the traffic flow, and it is a typical bottleneck. The U-turn movement can cause phase transition at small probability of vehicle generation and the critical flow also decreases obviously. The system with two U-turn movement is different from the system with one U-turn movement in traffic features such as phase transition and critical flux. The one U-turn system has a good performance. It is suggested that the system with a couple of U-turns may help mitigate the negative effect of U-turn movement in traffic planning and management.
A evolving network model generated by random walk and policy attachment
Authors: Jiang Zhi-Hong  , Wang Hui  , Gao Chao  ,   College of Information Systems and Management, National University of Defense Technology, Changsha 410073, China
Published: December 2020

Real-world networks always present some complex network properties simultaneously, such as small-world, scale-free, high clustering and assortative/disassortative mixing, etc. , but only part of these properties can be reproduced in most of complex network models. In this paper, a new complex network model generated by random walk and policy attachment(RAPA) is proposed. A new peer constructs a local world by random walking, and attaches itself to peers in the local world following the policy of "random selection", "poverty alleviation" or "favoring the rich". The results of analysis computing and simulation demonstrate that RAPA model can reproduce not only small-world and scale-free features, but some non-power-law features such as exponential cutoff and saturation for small variables. In addition to these, RAPA model also constructs some networks with evident clustering structure and assortative/disassortative mixing pattern.
A new ldea of cloud motion wind derived from satellite images
Authors: Long Zhi-Yong  , Shi Han-Qing  , Huang Si-Xun  ,   Institute of Meteorology, PLA University of Science and Technology, Nanjing 211101, China
Published: December 2020

In this paper we firstly use a new method——numerical differentiation, which was developed in recent years to calculate gray gradient, and then realize the inverse cloud motion wind by regularization. At last, through simulation and practical experiments, we compared the wind inverse results between the algorithms with or without gray gradient information when the cloud images include perturbation. The experimental results show that the new algorithm with gradient information can reduce the influence of image disturbance effectively, and also increase the precision of cloud motion winds. We are in a position to find a new way to cloud motion wind inversion.
Atmospheric physical characteristics of dew formation in semi-arid in loess plateau
Authors: Wang Sheng  , Zhang Qiang  ,   Key Laboratory for Semi-Arid Climate Change of the Ministry of Education, College of Atmospheric Sciences, Lanzhou University, Lanzhou 730000; Institute of Arid Meteorology, CMA; Key laboratory of Arid Climatic Change and Reducing Disaster of Gansu Province; Key Open Laboratory of Arid Climatic Change and Disaster Reduction of CMA, Lanzhou 730020, China
Published: December 2020

Based on the data measured in 2009 in the DingXi, a typical semi-arid region in loess plateau, the temporal variation of condensed water and the influence factors are investigated. Meanwhile, the measurements of condensed water, made by weighing approach and eddy-correlation approach separately, are compared in this work. The results show that in the semi-arid regions in Loess Plateau, the daily maximum amount of condensation can reach 0.33 mm, the daily minimum recorded is 0.09 mm, and the average daily amount is 0.23mm. No obvious correlations is found between the amount of condensation and wind velocity, relative humidity, temperature, or land-air temperature difference. In the process of dew formation, the relative humidity which supplies the water vapor for condensing is an internal factor. The temperature which is motive power for condensing process is a key factor. The wind speed has an important effect and is an uncertain factor, which promotes but also can restrain the dew formation. It is also found that the following conditions favor the condensation process: wind speed of 0.5—2 m/s, relative humidity> 80% and land-air temperature difference <± 2℃.
Extraction algorithm for retrieving the effective constitutive parameters of metamaterials based on TE10 rectangular waveguide
Authors: Gong Jian-Qiang  , Liang Chang-Hong  ,   National Key Laboratory of Science and Technology on Antennas and Microwaves, Xidian University, Xi'an 710071, China
Published: December 2020

A novel retrieval method of the effective constitutive parameters of metamaterials based on TE10 rectangular waveguide is proposed, which is adopted to extract effective relative permittivity ε and permeability μ for the composite ferrite and wire array metamaterial in multiple symmetrical unit cell configuration. Much attention has been paid to choose the correct branch of the real part of the propagation constant β for the metamaterial with multiple unit cells, and in terms of the relationship between the measured values and theoretical values in the measurement theory, β values in the case of multiple unit cells are determined by taking the extracted β values for a single unit cell as the measured values for the multiple unit cells case. Owing to the coupling effect between the unit cells of the metamaterial with multiple unit cells, the electromagnetic wave mainly behaves as the periodic Bloch wave, which is usually negligible for a single unit cell, so the extracted effective constitutive parameters for a single unit cell generally can not be assigned as those for the metamaterial with multiple unit cells directly. However, β values for a single unit cell is generally prone to be extracted, which can be the first step to extract the β values in multiple unit cells case. It is pointed out that the extracted effective constitutive parameters can be physically meaningful only if attenuation coefficients of higher Bloch wave modes are larger than that of the fundamental Bloch mode in the periodic metamaterial, and under this condition, higher Bloch wave modes will get further attenuated with increase of the unit cell number, leaving only the fundamental mode propagation, which makes the extracted ε and μ more stable and convergent.
Epidemic immunization on scale-free networks with traffic flow
Authors: Wang Ya-Qi  , Jiang Guo-Ping  ,   (1)Center for Control and Intelligence Technology, Nanjing University of Posts and Telecommunications, Nanjing 210003, China; (2)Center for Control and Intelligence Technology, Nanjing University of Posts and Telecommunications, Nanjing 210003, China; College of Automation, Nanjing University of Posts and Telecommunications, Nanjing 210003, China
Published: December 2020

In this paper, considering the influence of network traffic flow on the spreading behaviors of epidemics and according to the mean-field theory, we investigate the epidemic immunization strategies in scale-free networks, and propose an improved acquaintance immunization mechanism. Theoretical analysis shows that considering the influence of traffic flow, the random immunization can hardly reduce the spreading velocity of epidemics if the density of vaccinated nodes is small. However, the targeted immunization can sharply depress the epidemic spreading even only a tiny fraction of nodes are vaccinated, and the effects of immunizing the most highly connected nodes and vaccinating the nodes with the largest betweenness are almost the same. We also find that if the network global information is unknown, compared with the classical acquaintance immunization strategy, the strategy proposed in this paper can be used to obtain good immune effect. Numerical simulations confirm the theoretical results.
A new quantum teleportation protocal
Authors: Bing He  , He Rui  ,   (1)Department of Material and Chemical Engineering, West Anhui University, Liuan 237012, China; (2)Institute for Quantum Information Science, University of Calgary, Alberta T2N 1N4, Canada
Published: December 2020

A new quantum teleportation protocol is addressed in this article. By performing the joint measurement of number-phase on a pair of independent two-mode squeezed vacuum states (1- 2 and 3- 4 systems), whose squeezed parameters are the same, the entangled states of the other two bodies (1- 4 systems) as the entangled resource are prepared. Thus the quantum teleportation is successfully realized.
Scheme for generating maximally two-mode entangled state in an S=1 antiferromagnetic Bose-Einstein condensation
Authors: Xu Yan  , Fan Wei  , Chen Bing  , Li Zhao-Xin  ,   (1)College of Science, Shandong University of Science and Technology, Qingdao 266510, China; (2)College of Science, Shandong University of Science and Technology, Qingdao 266510, China; Key Laboratory for Magnetism and Magnetic Materials of Ministry of Education, Lanzhou University, Lanzhou 730000, China
Published: December 2020

We propose a scheme to generate maximally two-mode entangled state in a spinor-1 anti-ferromagnetic Bose-Einstein condensation. We reduce the three-level system into an effective two-level system via the quantum Zeno subspace created by exerting strong Raman coupling. We investigate the particle number evolution in the unreduced system to justify the existence of Zeno subspace and find that the effective system can be trusted and the entanglement production is reliable.
Hopf bifurcation and chaotification of Josephson junction with linear delayed feedback
Authors: Zhang Li-Sen  , Cai Li  , Feng Chao-Wen  ,   School of Science, Air Force Engineering University, Xi’ an 710051, China
Published: December 2020

In this paper, a resistive-capacitive-shunted Josephson junction with linear delayed feedback is considered. The stability of trivial solution of the controlled system is analyzed using nonlinear dynamics theory, and the theoretical results show that the stable trivial solution of the system will lose its stability via Hopf bifurcation as control parameter varies. The critical parameter condition of Hopf bifurcation is also derived. Numerical analysis of the controlled system is carried out under different parameter conditions, and the results show that the stable periodic solution generated by supercritical Hopf bifurcation may transit to chaos gradually through a process of symmetry-breaking bifurcation and period-doubling bifurcation.
Langevin equation and its applications in the simulation of protein folding process
Authors: Sun Li-Feng  , Jiang Ze-Nan  , Fang Chao  ,   (1)Department of Physics, Simon Fraser University, Burnaby, BC V5A 1S6, Canada; (2)Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084, China
Published: December 2020

Some ideas concerning the properties of Langevin equation and its applications to the protein folding process are introduced in this paper. Continuous mapping of Langevin equation is constructed in the phase space and a clear inhomogeneous distribution at position of the Brownian particles is discovered, which is consistent with the hypothesis of the nonergodicity of space structure of protein molecule in the folding process. Besides, a random coil with the same compactness index as proteins in the denatured state is obtained by simulation under the self-avoiding walk condition. Taking the hydrophobic effects as well as the renormalization model into consideration, we present the method to simulate the process of protein shrinking from a random coil to a molten globule.
Cryptanalysis of a hyper-chaotic image encryption algorithm and its improved version
Authors: Wang Jing  , Jiang Guo-Ping  ,   (1)Center for Control and Intelligence Technology, Nanjing University of Posts and Telecommunications, Nanjing 210003, China; (2)Center for Control and Intelligence Technology, Nanjing University of Posts and Telecommunications, Nanjing 210003, China; College of Automation, Nanjing University of Posts and Telecommunications, Nanjing 210003, China
Published: December 2020

According to the Kerckhoff principle, a kind of image encryption algorithm based on hyper-chaos is discussed through choosing plaintext attack and ciphertext attack. The result shows that the key stream is independent of plaintext and one plain-text word is correlated with single cipher-text word for the algorithm, which makes the ciphertext decrypted easily with little computing by choosing plaintext and ciphertext attack. Considering the above problems, an improved algorithm based on hyper-chaos is proposed and the performance analysis is conducted, including statistical analysis, differential analysis, correlation analysis and key sensitivity testing. Theoretical analysis and simulation results show that the improved algorithm not only can resist the chosen plaintext attack and chosen ciphertext attack, but also can obtain better cryptographic properties, such as statistical characteristics, difference characteristics and so on.
Cellular automaton traffic flow model considering influence of accidents
Authors: Qian Yong-Sheng  , Zeng Jun-Wei  , Du Jia-Wei  , Liu Yu-Fei  , Wang Min  , Wei Jun  ,   School of Traffic and Transportation, Lanzhou Jiaotong University, Lanzhou 730070, China
Published: December 2020

Based on the NaSh model, considering the influence of traffic accident and maintenance of highway sections on traffic flow, the cellular automaton model of highway traffic flow under the lane control is established when accident occurs. And the relevant data of the model are calculated. Through analyzing the results of numerical simulation it is found that the accident has a great influence on the highway traffic flow and considerably on traffic flow density within a certain range. And the influence of the accident blocking point on traffic flow on lane 1 is less than on lane 2. Meanwhile, in this range of traffic flow density, the longer the blocking time and the length of blocking section, the greater the influence of traffic flow is.
Adaptive backstepping control of chaotic property in direct-driveven permanent magnet sychronous generators for wind power
Authors: Zheng Gang  , Zou Jian-Xiao  , Xu Hong-Bing  , Qin Gang  ,   University of Electronic Science and Technology of China,Chengdu 611731, China
Published: December 2020

In this paper, a mathematical model of direct-driven permanent magnet synchronous generator(D-PMSG) is derived with taking into account the parametric uncertainty and the disturbance of wind. And also the chaotic property under the condition of certain system parameters and a certain operation is verified. Furthermore,the adaptive backstepping approach is designed to compensate the parametric uncertainty and wind disturbance. The simulation results show that the proposed controller for D-PMSG is effective and robust against the parametric uncertainty and the wind disturbance.
A new smooth quadratic chaotic system and its digital signal processing implementation
Authors: Liu Yang-Zheng  , Lin Chang-Sheng  , Li Xin-Chao  ,   Institute of Nonlinear Physics, Nanjing Institute of Technology, Nanjing 211167, China
Published: December 2020

Developing and changing nonlinear function of Lorenz chaotic system, a new autonomous chaotic system is generated which contains three smooth quadratic terms of system variables and five equilibriums. The characteristics of five equilibriums are discussed and a fractal dimension is calculated. The features of chaotic system are analyzed in detail using bifurcation diagram and Lyapunov exponent. The period doubling bifurcation of the system can occus. The chaotic system is realized based on digital signal processing. Experimental result shows the effectiveness and feasibility of the theoretical analysis and verifies the behaviors of various attractors.
Modified Hénon map generated chaotic pseudorandom-bit sequences and performance analysis
Authors: Li Jia-Biao  , Zeng Yi-Cheng  , Chen Shi-Bi  , Chen Jia-Sheng  ,   Department of Optoelectronic Engineering, Institute of Intelligent Optoelectronic Technology, Xiangtan University, Xiangtan 411105, China
Published: December 2020

A method of improving the traditional Hénon map is proposed in the paper. The internal structure of the system is changed by adopting absolute value term. The linear complexity and sensitivity to initial conditions of the proposed system have been greatly enhanced. The performance of pseudorandom-bit sequences which are generated by the proposed system is analyzed in comparison with the ones that are generated by chaotic system. The performance of the sequence generated by the proposed system is improved compared with the original system. Theoretical analysis and the simulation results show the feasibility of the method.
Maximum trap range and equation of state for Fermi gas in potential trap
Authors: Yuan Du-Qi  ,   Department of Physics and Information Technology, Baoji University of Science and Arts, Baoji 721016, China
Published: December 2020

In the Thomas-Fermi semi-classical approximation, the maximal trap range and the real trap volume of ideal Fermi gas in an n-dimensional potential trap are gaven, and the relevant equations of state are derived. These results indicate that the maximal trap range and the real pressure of trapped gas are related to the potential field and the chemical potential of the free and ideal Fermi system. When the Thomas-Fermi approximate is valid and the condition ((kT)/(hω))2 ((16π2g)/(9N))2/3<<1 is satisfied, the application of the equation of state to three-dimensional spherical symmetry harmonic trap yields the result that the change of pressure is not obvious when the temperature changes, but the change of pressure is closely related to mass of particle, number of particles and the frequency of harmonic potential.
Stochastic bifurcations in Duffing-van der Pol oscillator with Lévy stable noise
Authors: Gu Ren-Cai  , Xu Yong  , Hao Meng-Li  , Yang Zhi-Qiang  ,   Department of Applied Mathematics ,Northwestern Polytechnical University,Xi'an 710129,China
Published: December 2020

This paper aims to investigate the influence of Lévy stable noise on a bistable Duffing-van der Pol oscillator. We obtain the stationary probability density function of amplitude for the Duffing-van der Pol oscillator by use of Monte Carlo method, and analyze the influences of the noise intensity and the stability index on the stationary probability density. Stochastic bifurcations are further discussed though a qualitative change of the stationary probability distribution, which indicates that not only system parameters and noise intensity can be treated as bifurcation parameters, but also the change of the stability index will induce stochastic bifurcations.
Simultaneous experimental reconstruction of three-dimensional flame soot temperature and volume fraction distributions
Authors: Liu Dong  , Yan Jian-Hua  , Wang Fei  , Huang Qun-Xing  , Chi Yong  , Cen Ke-Fa  ,   (1)State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, China; (2)State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, China; Centre de Thermique de Lyon, Insa de Lyon, 69621, Lyon, France
Published: December 2020

Three-dimensional (3D) flame soot temperature and volume fraction distributions are simultaneously reconstructed experimentally by the simultaneous reconstruction model through using charge-coupled device cameras. The reconstruction model is based on the area reconstruction. The reconstructed 3D soot temperatures and volume fraction distributions are compared with those reported in the literature. The reconstructed temperatures are also compared with those measured by thermocouples. It is shown that the reconstructed temperature distribution and the volume fraction distribution are consistent with the reported results. The reconstructed temperatures in good agreemant with the measured temperatures by thermocouples. So the simultaneous reconstruction model can obtain the soot temperature and volume fraction distributions successfully.
Analyses for the stability of multi-gap Hughes-type coupled cavity
Authors: Cui Jian  , Luo Ji-Run  , Zhu Min  , Guo Wei  ,   (1)Key Laboratory of High Power Microwave Sources and Technologies, Institute of Electronics, Chinese Academy of Sciences, Beijing 100190, China; (2)Key Laboratory of High Power Microwave Sources and Technologies, Institute of Electronics, Chinese Academy of Sciences, Beijing 100190, China; Graduate University of Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

In this paper, the analytical expressions of the beam-wave coupling coefficient and the beam-loaded conductance in the N-gap Hughes-type coupled cavity used in an extended- interaction klystron are derived based on the space-charge wave theory. The stability of the circuit is discussed through calculating the quality factor of the electron beam. The theoretical analyses show that with the increase of N, the stability of operating mode (2π) becomes more sensitive to the beam voltage, and that the parasitical oscillation may more easily occur and is difficult to suppress. In addition, the increase of the perveance and the decrease of the external loaded quality factor may both cause the instability of the system. The electric field intensities on the gap are greatly different among the modes 2π, π and π/2, which may be a new subject for improving the power capability and the bandwidth in klystron development.