bluuebunny/crossref_metadata_2025 huggingface dataset:
Stability and time-delayed feedback control of a relative-rotation nonlinear dynamical system under quasic-periodic parametric excitation
Authors: Li Ji-Zhao  , Liu Bin  , Han Dong-Ying  , Shi Pei-Ming  ,   (1)College of Electrical Engineering, Yanshan University, Qinhuangdao 066004, China; (2)College of Vehicles and Energy, Yanshan University, Qinhuangdao 066004, China
Published: December 2020

The dynamical equation of a relative-rotation nonlinear dynamic system, which contains quasi-periodic parametric excitation and time delays, is established. Bifurcation response equation of 1/2 subharmonic primary parametric resonance is obtained by the method of multiple scales, and the stability of the system is analyzed. By solving the steady state solutions of the uncontrolled system, the effect of quasi-periodic parametric excitation on system response is studied through discussing the dynamics of the system. Time-delay feedback control method is used to control the bifurcation and limit cycle(region). Numerical results show that the bifurcation and the stability of the limit cycle(region) are controlled effectively by changing the time-delay parameters.
New properties of streamwise streaks in transitional boundary layers
Authors: Tang Deng-Bin  , Liu Chao-Qun  , Chen Lin  ,   (1)Department of Aerodynamics, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China; (2)Department of Mathematics, University of Texas at Arlington, Arlington, Texas 76010, USA
Published: December 2020

Based on detailed results of direct numerical simulation with high order accuracy and resolution at the late-stages of the transitional boundary layer, new properties are found, such as discontinuous event in the evolution of low-speed streamwise streaks and the appearance called high speed spots in the development of high-speed streamwise streaks. In the present paper, the complex vortex structures and the ejection-sweep phenomenon in the transition process of boundary layers are analyzed thoroughly, and the new properties of high-speed /low-speed streamwise streaks are confirmed to be closely relatcd to the evolution process of vortex structures in the flow-field.
Density measurement and MHD simulation ofgas-filled capillary discharge waveguide
Authors: Gu Yu-Qiu  , Ma Zhan-Nan  , Zheng Wu-Di  , Wang Xiao-Fang  , Wu Yu-Chi  , Zhu Bin  , Dong Ke-Gong  , Cao Lei-Feng  , He Ying-Ling  , Liu Hong-Jie  , Hong Wei  , Zhou Wei-Min  , Zhao Zong-Qing  , Zhang Bao-Han  , Jiao Chun-Ye  , Wen Xian-Lun  , Zang Hua-Ping  , Yu Jin-Qing  , Wei Lai  ,   Institute of Applied Physics and Computational Mathematics, Beijing 100088, China;,   Key Laboratory of Basic Plasma Physics of Chinese Academy of Sciences, Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China;,   Science and Technology on Plasma Physics Laboratory, Laser Fusion Research Center, China Academy of Engineering Physics, Mianyang 621900, China;,   Science and Technology on Plasma Physics Laboratory, Laser Fusion Research Center, China Academy of Engineering Physics, Mianyang 621900, China;Key Laboratory of Basic Plasma Physics of Chinese Academy of Sciences, Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China
Published: December 2020

To accelerate the electrons efficiently in the laser wake-field accelerator, it is necessary to suppress the instability induced by the diffraction and the defocusing of the laser pulse. The gas-filled capillary discharge waveguide can generate an approximately parabolic density distribution, which can guide the laser pulse efficiently and suppress the instability. Using the Stark effect, this plasma density distribution is measured in this paper, and the relationship between plasma density and filled pressure is presented. By using the MHD code CRMHA, the formation of the capillary waveguide is simulated and researched in detail.
Molecular dynamics simulations of energy effectson atorn F interaction with SiC(100)
Authors: Zhao Cheng-Li  , Lü Xiao-Dan  , Ning Jian-Ping  , Qing You-Min  , He Ping-Ni  , Gou Fu-Jun  ,   (1)Institute of Plasma Surface Interactions, Guizhou University, Guiyang 550025, China; (2)Institute of Plasma Surface Interactions, Guizhou University, Guiyang 550025, China;science College of Guizhou University, Guiyang 550025, China; (3)Key Laboratory for Radiation Physics and Technology Ministry of Education, Institute of Nuclear Science and Technology, Sichuan University,Chengdu 610064, China;FOM Institute for Plasma Physics, 3439 MN Nieuwegein, Netherlands
Published: December 2020

In this study, molecular dynamics simulations are used to investigate atom F interacting with SiC at 300 K. Simulation results show that with the saturation of the deposition of F atoms on the surface, the compositions (SiFx and CFx groups (x4 is dominant. And the main etching mechanism of Si atoms is chemical etching.
Dynamic buckling of double-walled carbon nanotubesunder axial impact loading
Authors: Yao Xiao-Hu  , Zhang Xiao-Qing  , Han Qiang  ,   Department of Engineering Mechanics, School of Civil Engineering and Transportation, South ChinaUniversity of Technology, Guangzhou 510640, China
Published: December 2020

Using the modified finite element method, the nonlinear shell-spring finite element model is established with taking the van der waals force into account. Based on the B-R motion criterion, the dynamic bucking behaviors of multi-walled carbon nanotubes are examined systemically. The dynamic critical loads for buckling and failure of double-walled carbon nanotubes under axial impact load are obtained. It is shown that in the dynamic buckling process of multi-walled carbon nanotubes, the deformation of each wall is harmonious to each other and the change of interlayer spacing is very small. The magnitude and the duration of impact load as well as the length of carbon nanotube have greater effects on the dynamic buckling of carbon nanotubes. For the shorter carbon nanotubes, asymmetrical buckling mode appears earlier. The simulations further show that the stress wave propagation in carbon nanotubes induces the asymmetrical buckling mode. In the dynamic buckling process of carbon nanotubes, there are four circumferential lobes that can be observed obviously, and their wave crest and trough of the lobes change alternately.
First-principles study on electronic structure and half-metallicferromagnetism of ternary compound ZnCrS
Authors: Nie Zhao-Xiu  , Wang Feng  , Cheng Zhi-Mei  , Wang Xin-Qiang  , Lu Li-Ya  , Liu Gao-Bin  , Duan Zhuang-Fen  ,   (1)College of Elementary Education, Chongqing Normal University, Chongqing 400700, China; (2)College of Physics, Chongqing University, Chongqing 400044, China; (3)College of Physics, Chongqing University, Chongqing 400044, China;College of Education Sciences, Chongqing Normal University, Chongqing 400047, China
Published: December 2020

The model of the ternary compound ZnCrS2 is constructed by replacing the Zn atoms in the zinc-blend phase ZnS with Cr at two different positions a and b in a ratio of 1∶1. Then the electronic and the magnetic properties of ZnCrS2 are invescigated by using the plane wave pseudopotential (PWPP) method with the density functional theory (DFT). The results show that both kinds of ZnCrS2 are more stable in the ferromagnetic state than in the anti-ferromagnetic state, and are half-metallic ferromagnets with half-metallic band gaps of 0.964eV and 0.755 eV, respectively. The comparison of two different models reveals that ZnCrS2 in a-position replacement is more sable and also has a larger half-metallic band gap. Furthermore, the spin-polarized electronic density of states, the band structure and the magnetic moment of ZnCrS2 are analyzed in detail. The present results should be useful for the future experimental study.
Fabrication and optical properties of ZnO/ZnMgO multiple quantum wells on m-sapphire substrates
Authors: Lü You-Ming  , Mei Ting  , Su Shi-Chen  ,   (1)College of Materials Science and Engineering, Shenzhen University, Shenzhen 518060, China; (2)Key Laboratory of Electroluminescent Devices, Department of Education of Guangdong Province, China Institute of Optoelectronic Material and Technology, South China Normal University, Guangzhou 510631, China
Published: December 2020

The ZnO/Zn0.85Mg0.15O multiple quantum wells(MQWs)are fabricated on m-Al2O3 substrates by plasma-assisted molecular beam epitaxy (P-MBE) using a ZnMgO buffer layers. The reflection high-energy electron diffraction (RHEED) images indicate that the MQWs are of two-dimensional growth .The temperature dependent photoluminescence (PL) of the MQW also shows the quantum confine effect even at room temperature. The PL peak of 3nm MQW is 3.405 eV at 290 K.The PL spectrum in ZnO/Zn0.85Mg0.15O MQW is dominated by localized exciton emission at low temperatures, while the free exciton transition gradually dominates the spectrum at higher temperatures up to room temperature. The exciton binding energy in the 3 nm ZnO/Zn0.85Mg0.15O MQW is about 73 meV.
Effect of N-doping on band structure and transport property of zigzag graphene nanoribbons
Authors: Lin Qi  , Chen Yu-Hang  , Wu Jian-Bao  , Kong Zong-Min  ,   Shanghai University of Engineering Science, Shanghai 201620, China
Published: December 2020

The energy band structure, the transmission spectrum and the current-voltage characteristics of the N-doped zigzag graphene nanoribbons (z-GNRs) have been investigated by performing first-principles calculations. The results show the appearance of energy gap and a metal-semiconductor transition induced by N-doping of z-GNRs. With impurity concentration increasing, the current under the same bias decreases significantly, while the transmission coefficient near the Fermi surface decreases gradually. In addition, the length, the width and the N-doping position of z-GNR affect the transport property. Especially, the impurity concentration competes with the N-doping position in the influence on the transport property for narrow z-GNRs.
Wave packet dynamics of two extended Harper models
Authors: Zhang Zhen-Jun  , Yu Miao  , Gong Long-Yan  , Tong Pei-Qing  ,   Department of Physics, Nanjing Normal University, Nanjing 210097, China
Published: December 2020

We study the wave packet dynamics of two extended Harper models by using the second moment M2(t) and probability distribution Wn(t) numerically. The dynamical behaviors of two extended Harper models in all phases, on all phase boundary lines, and at the bicritical points are studied. For the first extended Harper model, we find that the wave packet is of ballistic diffusion in two metal phases, localized in the insulator phase, and of anomalous diffusion on the phase boundary lines and at the bicritical point. We also find the dynamical behavior on the boundary line of the metal-metal phase transition is the same as that on the metal-insulator phase transition. The spreading at the bicritical point is different from that on the phase boundary lines. For the second extended Harper model, we find that the wave packet is of ballistic diffusion in the metal phase, localized in the insulator phase, and of anomalous diffusion in the critical phase, on the phase boundary lines, and at the bicritical point. We also find the dynamical behavior on the boundary line of the critical-metal phase transition is similar to that at the bicritical point and the critical-insulator phase transition, but different from that of the metal-insulator phase transition.
A novel charge generation layer for stacked organic light-emitting devices
Authors: Chen Ping  , Zhao Li  , Duan Yu  , Cheng Gang  , Zhao Yi  , Liu Shi-Yong  ,   State key Laboratory of Integrated Optoelectronics,Jilin University, Changchun 130012, China
Published: December 2020

We report on a novel charge generation layer(CGL) of LiF/Al/V2O5 for a stacked organic light-emitting device(SOLED). The two emitting units of SOLED based on the CGL are independent as if they are individual devices. The CGL has an ability to inject electrons and holes into two adjacent emitting units. The luminance efficiency of the SOLED based the CGL is 1.7 times of the control device at the same current density. Moreover, the novel CGL can be prepared only with thermal evaporation without sputtering TIO or co-evaporation of metal and organic material during device fabrication, thus making the device processing.
Electronic structure of zigzag graphene nanoribbin terminated by hydroxyl
Authors: Tao Qiang  , Hu Xiao-Ying  , Zhu Pin-Wen  ,   (1)College of Science, Changchun University, Changchun 130022, China; (2)College of Science, Changchun University, Changchun 130022, China;State Key Lab of Superhard Materials, Jilin University, Changchun 130012, China; (3)State Key Lab of Superhard Materials, Jilin University, Changchun 130012, China
Published: December 2020

Using the density-functional theory, the structural stability and the effect of in-plane electric field on the electronic structure of zigzag graphene nanoribbin (OH-ZGNR), which is terminated by hydroxyl, are explored. It is found that hydroxyl bonding on the ZGNR edge is much more stable than H-terminated ZGNR(H-ZGNRs). The ground state of the ZGNR is spin-polarized with a narrow energy gap. Furthermore, transition from semiconducting to metallic phase in ZGNR can be achieved if a proper in-plane electric field is applied across the edges OH-ZGNR.
Preparation and mechanism of In-doped ZnO emitting white-light
Authors: Li Shi-Shuai  , Zhang Zhong  , Huang Jin-Zhao  , Feng Xiu-Peng  , Liu Ru-Xi  ,   School of Science, University of Jinan, Jinan 250022, China
Published: December 2020

Pure ZnO films and In/ZnO films are prepared by sol-gel process on Si substrates.The ratio of In/(Zn+In) are 5%, 8% and 10% separately. Crystal phase structures and photoelectric properties of these films are characterized and these chromaticity coordinates of different samples are also calculated in a CIE-XYZ color system. The results show that preferred growth direction of ZnO film changes from (002) plane to (001) plane and interplanar distance becomes shorter. When doping amount of In is 5%, Zn atoms are replaced by In atoms. Resistivity of the film first decreases and the increases with the increase of the amount of In. Ultraviolet emission peak of spectrum has a redshift; a new peak emerges at 670nm with the increase of In. The sample of 5% emits white-light.The band structures of pure and 5% doping content of film are calculated based on first principles.The mechanism of emitting white-light is discussed from the view point of additional energy level.
Effects of arrangement of scatterers on band gaps of two-dimesional magnonic crystals
Authors: Wang Li-Yong  , Cao Yong-Jun  ,   (1)College of Physics and Electronic Information, Inner Mongolia Normal University, Huhhot 010022, China; (2)College of Physics and Electronic Information, Inner Mongolia Normal University, Huhhot 010022, China;College of Physical Science and Technology, Inner Mongolia University, Huhhot 010020, China
Published: December 2020

In this paper, band structures of two-dimensional magnonic crystals with square arrangement, triangle arrangement and honeycomb arrangement of Fe cylinders in matrix of EuO are calculated by the plane-wave expansion method. And the effects of arrangements of scatterers on the band gaps of two-dimensional magnonic crystals are discussed. The numerical results show that the gap of the triangle arrangement is the largest in the above three lattices.
Magnetic properties of N-doped(1120) ZnO thin films
Authors: Li Ming-Biao  , Zhang Tian-Xian  , Shi Li-Bin  ,   School of Mathematics and Physics, Bohai University, Jinzhou 121013, China
Published: December 2020

By using the first principles method based on the density function theory (DFT) and the local density approximation (LDA), we study the ferromagnetic properties in N-doped(1120) ZnO thin films. Magnetic properties in one-N-doped ZnO are investigated. The spontaneous spin polarization comes from N 2p, O 2p and Zn 3d. Magnetic properties in two-N-doped ZnO are also investigated. The calculated results show that ferromagnetism (FM) coupling between N atoms is more energetically favorable for nine geometrically distinct configurations. The origin of the FM state in N-doped ZnO is also discussed by analyzing the coupling of N levels. Finally, the magnetic exchange coefficient and the Curie temperature are discussed. The result indicates that N-doped ZnO thin films show weak FM properties.
Crytallographic orientation and magmetostriction of FeGa crystals
Authors: Li Chuan  , Liu Jing-Hua  , Chen Li-Biao  , Jiang Cheng-Bao  , Xu Hui-Bin  ,   Key Laboratory of Aerospace Materials and Performance (Ministry of Education) School of Materials Science and Engineering, Beihang University, Beijing 100191, China
Published: December 2020

Fe81Ga19 single crystals and polycrystals with different orientations are prepared by zone melting directional solidification. Pole figures show that the deviation degrees between [001] orientation and axis are 12°, 5° and 3°, and the in corresponding axial magnetostrictions parallel to external magnetic field are 254×10-6, 271×10-6 and 291×10-6. The[001]orientation single crystal is determined by back-reflection Laue, and the magnetostriction is 312×10-6. The results reveal the relationship between crystallographic orientation and magnetostriction, and the increase of magnetostrictions with deviation degree decreasing. The deviation degrees between [001]orientation and axis of polycrystals are determined by Electron Backscattered Diffraction to be 18.4°, 15.2° and 14.8°, and thir corresponding magnetostrictions are 180×10-6m, 230×10-6 and 235×10-6.
Influence of high-permeability FeCuNbSiB alloy on magnetoelectric effect of FeNi/PZT laminated composite
Authors: Wen Yu-Mei  , Wang Dong  , Li Ping  , Chen Lei  , Wu Zhi-Yi  ,   College of Optoelectronic Engineering,The Key Laboratory for Optoelectronic Technology & Systems, Ministry of Education, Chongqing University, Chongqing 400030, China
Published: December 2020

A FeCuNbSiB/FeNi/PZT laminated composite is developed and comparatively studied with a FeNi/PZT laminated composite. The influence of high-permeability FeCuNbSiB alloy on applied DC magnetic field, piezomagnetic coefficient and optimal bias magnetic field of FeNi is investigated. The experimental results show that compared with in the two-phase FeNi/PZT, in the three-phase FeCuNbSiB/FeNi/PZT laminated composite, (i) the optimal bias magnetic field decreases from 200Oe to 55Oe, and the maximum magnetoelectric(ME) voltage coefficient increases from 1.59V/Oe to 2.77V/Oe; (ii) under small bias magnetic field, the ME voltage coefficient increases by a factor of 1.7—7.8; (iii) the sensitivity of the ME voltage coefficient for the laminated composite to a DC magnetic field increases from 19.1mV/Oe to 158.6mV/Oe. The variations in ME effect of three-phase composie result from the enhancement of magnetizetion at end faces, which is generated by introducing the high permeability material phase.
Influence of natural impurity on electronic structure and catalytic activity of pyrite
Authors: Guo Jin  , Li Yu-Qiong  , Chen Jian-Hua  ,   (1)College of Physics Science and Technology, Guangxi University,Nanning 530004, China; (2)College of Resources and Metallurgy, Guangxi University, Nanning 530004, China;College of Physics Science and Technology, Guangxi University,Nanning 530004, China; (3)School of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004, China
Published: December 2020

The electronic structures and the optical properties of pyrite containing twenty natural impurities, Co, Ni, As, Se, Te, Cu, Au, Ag, Mo, Zn, Tl, Sn, Ru, Pd, Pt, Hg, Cd, Bi, Pb and Sb, are investigated using the density functional theory and the plane wave pseudopotential method, and the catalytic activity of pyrite is discussed. For the transition metal-bearing pyrite, there are introduced impurity energy levels in the band contributing from impurity d orbital, while for the other metal and non-metal-bearing pyrite, the impurity energy levels are contributed from impurities s or p orbital. The presences of Cu, Mo, As, Au, Ag or Ni can enhance the electrocatalytic ability of pyrite to the oxygen reduction. All the impurities, except Zn, Mo, Ru, As, Sb, Se and Te, can enhance the ability of pyrite surface to capture electrons and hence the recombination rate of photoinduced electrons and holes wile be reduced. Calculations of optical properties indicate that Cd, Hg, Ru, Se, Te and Zn impurities each have small influence on the absorption band edge, while the presence of other impurity makes a red shift of absorption band edge of pyrite. Especially, the presences of Au and Ag impuritie increase the adsorption coefficient of pyrite by two orders of magnitude.
Simple theory of space-charge-limited current between concentric sphere
Authors: Li Fei  , Xiao Liu  , Liu Pu-Kun  , Yi Hong-Xia  , Wan Xiao-Sheng  ,   (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 high-power microwave diode design, the space-charge-limited current is important because of its relation to the diode property and the formation of the virtual cathode. Although the Langmuir–Blodgett law, as a numerical solution, is helpful, a simple functional expression is more convenient for practical research and can avoide the divergence of the series for large R\-c/R\-a. First principle is used to generalize two-dimensional space-charge-limited current for planar plane capacitor and coaxial cylinders, and its reliability has been examined adequately. In this paper we obtain the functional expression of space-charge-limited current for concentric sphere, and the space-charge field factor in this expression by comparing the classical Langmuir current with the current from concentric sphere.
Preparation of AlN nanowire macroscopic arrays
Authors: Li Zhi-Jie  , Tian Ming  , He Lian-Long  ,   (1)College of Science, Shenyang University of Technology, Shenyang 110178,China; (2)Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
Published: December 2020

AlN nanowire macro-arrays are successfully synthesized and characterized by the second template method. In the article we mainly research the process of preparing the AlN nanowire macro-arrays each with a certain orientation and uniform diameter by the chemical vapor deposition (CVD) method. Metal nanoparticles are prepared by CVD and self-assembled PS sphere templates, and then AlN nanowires macro arrays are compounded by the CVD on template and the metal nanoparticles on the template as a catalyst. The samples are observed by SEM and TEM, AlN nanowire macro-arrays have an area of about 0.3 mm×0.2 mm, they are well distributed, and have an average diameter of about 41 nm, an average length of about 1.8μm, distributed density and coverage of large macro-hexagonal AlN nanowire arrays. So a method to controllably prepare AIN macroscopic nanowire arrays is obtained.
Properties of white organic electroluminescent devices based on a new organic metal complex with quantum well structure
Authors: Wang Hua  , Xu Bing-She  , Meng Wei-Xin  , Hao Yu-Ying  , Liu Xu-Guang  , Xu Hui-Xia  ,   (1)College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024, China; (2)Department of Physics and Optoelectronics, Taiyuan University of Technology, Taiyuan 030024, China; (3)Key Laboratory of Interface Science and Engineering in Advanced Materials, Taiyuan University of Technology, Taiyuan 030024, China
Published: December 2020

A series of white organic electroluminescent devices with a quantum well structure were fabricated based on a new type of organic metal complex bis(2-(4-trifluoromethyl-2-hydroxyphenyl) benzothiazolate) zinc (Zn(4-TfmBTZ)2) by electroplex at NPB/Zn(4-TfmBTZ)2 interface. The results show that the introduction of the hetero-junction quantum well structure can increase effectively the efficiency of electroplex emission, color rendering index(CRI),and the color coordination stability. The optimized device ITO/NPB (60 nm)/Zn(4-TfmBTZ)2(3.0 nm)/NPB (4.0 nm)i> /Zn(4-TfmBTZ)2(30 nm) /Alq3 (30 nm)/LiF(1.5 nm)/Al(150 nm) is obtained with color coordinates of (0.324, 0.337), the highest CRI of 92.5, a maximal brightness of 2013 cd/m2, and a maximal efficiency of 1.03 cd/A,. This device shows very high color stability when the driving voltage is varied from 10 V to 14 V.
Numerical simulations of immiscible two-phase flow displacement based on 3D network model for fractal porous media
Authors: Zhao Ming  , Yu Boming  ,   (1)School of Physics Science and Technology, Yangtze University, Jingzhou 434023, China; (2)School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
Published: December 2020

In order to describe the pore scale fractal distribution, we present a 3D network model for fractal porous medium in this paper. According to the proposed model we simulate the immiscible two-phase flow displacement in a medium and study the viscous fingering pattern of displacement front influenced by the fractal dimension Df for pore size distribution and viscosity ratio M. The simulation results show that the capacity dimension Dh of the viscous fingering pattern decreases with Df and M increasing, and their quantitative relationship is derived by fitting the obtained data.
A new growth method of roughed p-GaN in GaN-based light emitting diodes
Authors: Li Shui-Qing  , Wang Lai  , Han Yan-Jun  , Luo Yi  , Deng He-Qing  , Qiu Jian-Sheng  , Zhang Jie  ,   Tsinghua National Laboratory for Information Science and Technology/State Key Lab on Integrated Optoelectronics, Department of Electronic Engineering, Tsinghua University, Beijing 100084, China;,   Xiamen Sanan Optoelectronics Co. Ltd., Xiamen 361009, China;,   Xiamen Sanan Optoelectronics Co. Ltd., Xiamen 361009, China;Tsinghua National Laboratory for Information Science and Technology/State Key Lab on Integrated Optoelectronics, Department of Electronic Engineering, Tsinghua University, Beijing 100084, China
Published: December 2020

A new growth method of roughed p-GaN has been demonstrated in this paper. First, some crystal seeds of p-GaN are obtained by utilizing low-temperature growth. Then, a p-GaN high-temperature expitaxy layer is grown on it subsequently with a fast growth rate, which will enlarge the roughness degree. Compared with the luminous flux of the conventional light emitting diode with flat p-GaN, the luminous flux is improved by 45%. Meanwhile, it is found that the problems of large reverse current and high forward bias aroused by the low-temperature epitaxy are also solved.
Radiation damage of space GaAs/Ge solar cells evaluated by displacement damage dose
Authors: Lan Mu-Jie  , Wu Yi-Yong  , Hu Jian-Min  , He Shi-Yu  , Yue Long  , Xiao Jing-Dong  , Yang De-Zhuang  , Zhang Zhong-Wei  , Wang Xun-Chun  , Qian Yong  , Chen Ming-Bo  ,   (1)Harbin Institute of Technology,School of Astronautics, Harbin 150001, China; (2)Harbin Institute of Technology,School of Material Science and Engineering,Harbin 150001, China; (3)Harbin Normal University,School of Physics and Electronic Engineering,Harbin 150001, China; (4)Shanghai Institute of Space Power-sources, Shanghai 200233, China
Published: December 2020

In this paper,the degradation of irradiated GaAs/Ge single junction (SJ) solar cells is evaluated under the orbital environments using the displacement damage dose method. Firstly the electric-property changes of the SJ solar cells are experimentally obtained with the fluencies of electrons and protons of various energies under ground-based irradiation simulators. Based on the experimenal results and the calculated non-ionization energy losses (NIELs) of the electrons and protons in GaAs, the equivalent exponent n is obtained to be 1.7 for various electron energies,while the equivalent coefficient Rep for electron displacement damage converted into that of protons is 5.2. Furthermore, a degradation formula of the electrical property of the domestic SJ solar cell is established as a function of displacement damage dose during the particle irradiation. Using the displacement damage technique, the orbital evolution of the electric property degradation of the domestic SJ cell is predicted in this paper. In the meantime, the shielding effects of the cover glass with different thicknesses are also evaluated.
Theoretical study on the ultra long armchair (n,n) single walled carbon nanotubes with first principle density functional theory
Authors: Wang Yan-Li  , Su Ke-He  , Wang Xin  , Liu Yan  ,   Key Laboratory of Space Applied Physics and Chemistry, Ministry of Education,School of Natural and Applied Sciences, Northwestern Polytechnical University, Xi’an 710072, China
Published: December 2020

The armchair (n,n) single walled carbon nanotubes with n=2—20 are studied by using the first principle density functional theory at the B3LYP/3-21G(d) level of theory combined with the periodic boundary conditions in simulating the ultra long tube model. The structure parameter, the energy, the band structure, and the energy gaps are obtained. The results show that the tube diameter and the energy of formation are closely related to n. The fitted analytical equations are developed with a correlation coefficient larger than 0.999. The energy gaps of (2,2) and (3,3) carbon nanotubes are 1.836 eV and 0.228 eV and the tubes have indirect energy gaps. For n=4 to 20, the energy gaps are quite small (between 0.027 eV and 0.079 eV), showing metal conductivity as well as direct energy gaps.
Dual-band quantum well infrared photodetectors with two ohmic contacts
Authors: Huo Yong-Heng  , Ma Wen-Quan  , Zhang Yan-Hua  , Huang Jian-Liang  , Wei Yang  , Cui Kai  , Chen Liang-Hui  ,   Laboratory of Nano-Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
Published: December 2020

Two-color quantum well infrared photodetectors (QWIPs) with two stacks of QW series have been grown by molecular beam epitaxy and processed into mesa structure devices with only two ohmic contacts by photolithography and wet chemical etching. By changing QWIP parameters, including barrier height, well width, doping level and period number, the total bias voltage can be distributed to the two stacks in such a way that the stacked structure will show different photoresponse characteristics. The photocurrent spectrum measurements demonstrate that sample 1 can work alternately between the two atmospheric windows of 3—5 μm and 8—12 μm by tuning the voltage, while sample 2 can photorespond simultaneously to the irradiation of the two atmospheric windows. In this paper, the physics behind the two-contact type of QWIP is discussed. The voltage tunability and the simultaneous photoresponse are attributed to the change of photoconductive gain with the bias voltage and the distribution of the total bias between the two series. We here focus the discussion on the voltage tunability of sample 1. Compared with the three-contact-per-pixel structure, two-contact-per-pixel structure can greatly facilitate the dual-band focal plane array (FPA) device fabrication and increase the FPA fill factor.
Study of physically modeling for small-scaled strained Si nMOSFET
Authors: Qu Jiang-Tao  , Zhang He-Ming  , Qin Shan-Shan  , Xu Xiao-Bo  , Wang Xiao-Yan  , Hu Hui-Yong  ,   Key Lab of Wide Band-Gap Semiconductor Materials and Devices, School of Microelectronics, Xidian University, Xi’an 710071, China
Published: December 2020

In this paper, quasi-2D threshold voltage model of strained Si nMOS with polycrystalline SiGe gate is established based on the Guass Law and its I-V character model is also built based on the current density equation. The influence of relevant parameter on threshold voltage is analyzed by numerical analysis, and the validity of the model is verified by device simulator.
Dynamical evolution of complex airline system
Authors: Qian Jiang-Hai  , Han Ding-Ding  , Ma Yu-Gang  ,   (1)School of Information Science and Technology, East China Normal University, Shanghai 200241, China; (2)Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China
Published: December 2020

As a typical open complex system, airline network usually interplays with the economic environment during its self-organized evolution. In this paper, we investigate empirically the correlation between gross domestic product (GDP) and the Chinese airline network (CAN). It is found that the degree of the node has formed a linear correlation with its corresponding GDP since 1998 while a year later the CAN began to exhibit double-power-law degree distribution. Based on the observation, the dynamical equation of CAN is derived. A multiplicative process-like evolution pattern, which strongly depends on the GDP growth rate, is obtained. We demonstrate that such a process coupled with the exponential increase of nodes can yield a double-power-law distribution. The simulation is applied to CAN and we find that the simulation result is in agreement with real CAN.
Seasonal changes in China during recent 48 years and their relationship with temperature extremes
Authors: Feng Guo-Lin  , Zhang Shi-Xuan  , Sun Shu-Peng  , Zhao Jun-Hu  ,   (1)College of Atmospheric Sciences, Lanzhou University, Lanzhou 730000,China; (2)College of Atmospheric Sciences, Lanzhou University, Lanzhou 730000,China;Laboratory for Climate Studies, National Climate Center, China Meteorological Administration, Beijing 100081, China; (3)Laboratory for Climate Studies, National Climate Center, China Meteorological Administration, Beijing 100081, China
Published: December 2020

With nonlinear similarity method, we divised the seasons for whole China on the basis of daily mean temperature, pressure, relative humidity and precipitation at 752 stations for the period 1961—2008, and analyze the seasonal division for eight regions of China and seasonal times. In addition, the relevant statistic data are established which contain the annual variation in frequency of extreme temperature in China. By combining these two research findings, their relationship over the past 48 years is found through correlation analysis and sensitivity test. The results show that: (1) in most areas of China, the spring and summer starting time move up, their durations are extended, autumn starting time changes a litter, and its duration is extended, while winter is pushed back the starting time, and its duration is shortened. (2) With the summer extending, the frequency of extreme high temperature is increased in most areas of China except East China, while the shortening of winter results in the frequency of extreme low temperature declining markedly. (3) The existence and the annual change of extreme high and low temperature are the reason why the lengths of summer and winter change, and they are also the main reason why the substantial fluctuations of the lengths of summer and winter take place.
Eliminating the influence of Faraday rotation on passive microwave remote sensing from space
Authors: Yan Wei  , Lu Wen  , Shi Jian-Kang  , Ren Jian-Qi  , Wang Rui  ,   Institute of Meteorology, PLA University of Science & Technology, Nanjing 211101, China
Published: December 2020

Faraday rotation (FR) is one of the important error sources for passive microwave remote sensing from space. In this paper, the principle of FR variation is studied. The influence of FR on accuracy for microwave radiometer measurement is analyzed. We concentrate on FR correction both at 1.4 GHz for the orthogonal channel brightness temperature Tv and at 10.7 GHz for the correlative channel brightness temperature U. By using the simulated observational data of spaceborne microwave radiometry at one point in Hainan province in 2006, we compare the effects of two approaches: correction by auxiliary data (IRI model correction) and correction by polarimetric mode (Yueh and Ribó methods). Noise generated by the Monte Carlo mode is included in the simulation. Then a new method of using TEC data released by international GNSS service (IGS) is proposed. For correction of Tv at 1.4 GHz, correction made by polarimetric mode is better than that by auxiliary data. Yueh method is best in effectiveness while IRI model method is worst. For the correction of U at 10.7 GHz, the correction by polarimetric mode is invalid, only correction by auxiliary data is valid. IGS data method greatly improves the correction accuracy and can replace the method of IRI model for nearly real time correction or final data correction.
Morphological control of artificial ionospheric hole and its short-wave propagation effects
Authors: Hu Yao-Gai  , Zhao Zheng-Yu  , Xiang Wei  , Zhang Yuan-Nong  ,   College of Electronic Information, Wuhan University, Wuhan 430079, China
Published: December 2020

As one of important and effective means for modifying the ionosphere, chemical release can produce artificial ionospheric holes attributed to ionization depletion, which also greatly affect the short-wave propagation. In this paper, a neural gas multi-point release dynamics model is proposed baseed on mono-point one, and then the morphological control effects of chemical substances, releasing altitude, releasing mode and mass on artificial ionospheric hole are discussed. Furthermore, the short-wave propagation effect of artificial ionospheric hole is simulated and investigated by the 3-D numerical ray tracing.
Bifurcation analysis of slow-fast behavior in modified Chua's circuit
Authors: Ji Ying  , Bi Qin-Sheng  ,   Faculty of Science, Jiangsu University, Zhenjiang 212013, China
Published: December 2020

The dynamics of four-order modified Chua's circuit with slow-fast effect has been investigated in this letter. Different types of bursting phenomena can be observed in numerical simulations. By introducing slow-fast analysis, the bifurcation mechanism for the periodic bursting solutions, especially for Fold/Fold bursting and Fold/Hopf bursting, is presented, which is different from the usual case. With the variation of the parameter, the periodic bursting can evolve to chaotic bursting.
Emergence of features in protein-protein interaction networks
Authors: Wan Xi  , Zhou Jin  , Liu Zeng-Rong  ,   Shanghai Institute of Applied Mathematics and Mechanics, Shanghai University, Shanghai 200072, China;,   Institute of System Biology, Shanghai University, Shanghai 200444, China
Published: December 2020

Scale-free connectivity, small-world pattern, hierarchical modularity and disassortative mixing are prominent features shared by most biological networks. Up to now, various network growth models invoking gene duplication and divergence have been proposed to understand the evolutionary mechanisms shaping the scale-free connectivity, small-world pattern and disassortative mixing . In this paper, we present an evolutionary model by introducing a rule of small preference duplication of a node and sequently divergence plus non-uniform heterodimerization meaning that the probability that an heterodimerization link is added between duplicated nodes is proportional to the number of common neighbors shared by these nodes based on biological background, showing that our model can almost display series of topological characteristics of real protein interaction networks, such as scale-free connectivity, small-world pattern, disassortativity of degree-degree correlation and hierarchical modularity. Our model may yield relevant insights into the evolutionary mechanism of protein interaction networks behind it.
A molecular simulation study on adsorption behavior of solid-liquid interface in KDP crystal
Authors: Zhou Guang-Gang  , Lu Gui-Wu  , Jiao Yu-Qiu  , Li Ying-Feng  , Wang Kun  , Yu Yang-Xin  ,   College of Science and State Key Laboratory for Heavy Oil Processing, China University of Petroleum, Beijing 102249;,   Department of Chemical Engineering, Tsinghua University, Beijing 100084, China
Published: December 2020

Through building “surface-molecule” interfacial adsorption structure model, the physical and the chemical absorptions of (001) interface and (010) interface of KDP crystal are studied by using molecular dynamics and density functional theory method, and the effect of temperature on physical absorption behavior is investigated. The result indicates that the absorption process and the growth habit of KDP surface are dominated by the chemical absorption, and the binding energy on (001) surface is 2.86 times that on (010) surface of KDP crystal. Near the saturation temperature, the binding energy between [H2PO4]- anion and crystal surface presents obviously an oscillation characteristic with the temperature varying, and the solution becomes unstable with the formation of anion clusters. With temperature decreasing from 323 K to 308 K, the binding energy of H2O decreases in general, but the binding energy of KDP molecular increases obviously, which indicates the dehydration process results from the competitive absorption between H2O and [H2PO4]-. The results obtained are of significance in identifying the surface kinetics process and developing more sophisticated crystal growth theories.
Brownian heat engine driven by temperature difference in a periodic double-barrier sawtooth potential
Authors: Cheng Hai-Tao  , He Ji-Zhou  , Xiao Yu-Ling  ,   Department of Physics, Nanchang University, Nanchang 330031, China
Published: December 2020

This paper has studied the thermodynamic performance of a Brownian heat engine, which is driven by temperature difference. Brownian particles move in the periodic double-barrier sawtooth potential with an external load force and contact with an alternating hot and cold reservoir. The kinetic energy change of the Brownian particles and the heat leak between hot and cold reservoir are considered simultaneously. The influence of the main parameters, including the height of barrier, the ratio of the low barrier to high barrier and the external load force, on the efficiency of Brownian heat engine is discussed in detail. When the heat leak between the two reservoirs is taken into account, the Brownian heat engine is irreversible, the efficiency is less than the Carnot efficiency. When the heat leak is small, the ratio of the low barrier to high barrier can increase the efficiency. The curve of the power output versus the efficiency is a loop-shaped one. When the heat leak is negligible, the curve of the power output versus the efficiency is an open-shaped one. The efficiency is still less than the Carnot efficiency, because the heat flow via kinetic energy change of the particles is irreversible.
The chaotic self-FM system and its FM code coupled synchronization
Authors: Hu Wen  , Li Jun-Ping  , Zhang Gong  , Liu Wen-Bo  , Zhao Guang-Hao  ,   College of Electronic and Information Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China;,   Nanjing Changjiang Electronics Group CO., LTD, Nanjing 210037, China;,   College of Automation Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China
Published: December 2020

We proposed a new chaotic system using the closed loop self-feedback frequency modulation (FM) technique where the current sample of the output signal of voltage-controlled oscillator (VCO) is transformed and used as the next input of VCO. The dynamical behavior of the system is investigated by Bifurcation diagram and Lyapunov exponents. The performance of the system is analyzed in terms of peak to average power ratio (PAPR), frequency spectrum and the correlation function of the output signal. The results show that the developed system has complicated dynamical behaviors, including bifurcation, multi-stability and chaos, and the generated chaotic signals have low PAPR and wide bandwidth. We also discussed the synchronization of the system by FM code. In circuit experiments, VCO is implemented by digital frequency synthesis. The experimental results are consistent with our theoretical analysis.
Analysis of periodic vibrational resonance induced by linear time delay feedback
Authors: Yang Jian-Hua  , Liu Xian-Bin  ,   Institute of Vibration Engineering Research, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China
Published: December 2020

Under the excitations of the high-frequency and weak low-frequency signals, the effects of linear time delay feedback on the vibrational resonance in overdamped bistable system and Duffing systems are investigated respectively. Both the analytical and the numerical results show that the response amplitude of the system to the low-frequency signal varies periodically with the delay parameter simultaneously (with two different periods, i.e., the periods of the two exciting signals). Numerical results also indicate that the delay feedback can induce vibrational resonance in the monostable Duffing system in which there exists no traditional vibrational resonance. By adjusting the delay parameter, not only the vibrational resonance can be effectively controlled, but also the response of the system to the weak low-frequency signal can be further improved.
Second harmonic multi-beam laser heterodyne measurement for small angle based on oscillating mirror sinusoidal modulation
Authors: Li Yan-Chao  , Wang Chun-Hui  , Gao Long  , Cong Hai-Fang  , Qu Yang  ,   National Key Laboratory of Tunable Laser Technology, Harbin Institute of Technology, Harbin 150001, China
Published: December 2020

In this paper, we propose a novel method of multi-beam laser heterodyne measurement for small angle based on sinusoidal modulation of simple harmonic motion oscillating mirror. By using the Doppler effect and heterodyne technology, by loading the information about small angle into the frequency difference of the multi-beam laser heterodyne signal, by using the frequency modulation of the oscillating mirror, this method can give many values of small angle after the multi-beam laser heterodyne signal demodulation simultaneously. Processing these values by weighted-average, small angle can be obtained accurately. This novel method is used to simulate measurement for small angle by MATLAB, the obtained result shows that the relative measurement error of this method is just 0.789677%.
Electrical read out of nano-electromechanical system signal by using graphene resonant channel transistor
Authors: Xu Yue-Hang  , Guo Yun-Chuan  , Wu Yun-Qiu  , Xu Rui-Min  , Yan Bo  ,   School of Electronic Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China
Published: December 2020

The direct radio frequency read out method based on local back-gate graphene resonant channel transistor (RCT) is studied by combining the operation principles of graphene field-effect transistor and mechanical resonator. A novel method of fabricating local gate graphene RCT is proposed, and a graphene RCT with 1 m 1 m dimension channel is realized based on exfoliation graphene. The measured resonant frequency of graphene RCT is in a range of 57.5-88.25 MHz at room temperature. This work is useful to pave the way of graphene application to Nano-eletromechanical system and high frequency low-noise amplifier.
Analysis of dynamic performance of metal rubber damping ring applied in high-speed rotor system
Authors: Li Sheng-Bo  , Yan Hui  , Jiang Hong-Yuan  , Chen Liang  ,   School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001, China;,   School of Mechanical Engineering, Heilongjiang Institute of Science and Technology, Harbin 150027, China
Published: December 2020

Based on the nonlinearity of metal rubber components and its different elastic damping mechanical properties with different structures, the mechanical model of hysteresis loop boundary deformation process of metal rubber components with different relative densities was established by the experiment method combining theory. Dynamic characteristics of metal rubber damping ring were analyzed under harmonic excitation load and experimental study was conducted. The elastic damping performance of the damper with preliminary deformation was researched and the experimental result showed good agreement with the theoretical analysis one, which provides a theoretical basis for practical application of this kind of damper.