bluuebunny/crossref_metadata_2025 huggingface dataset:
Solid state cathodoluminescence of poly (2-methoxy-5-(2-ethyl-hexyloxy)-1，4-phenylene vinylene in devices with Si3N4 as the electronic accelerating layer
Authors: Kong Chao  , Xu Zheng  , Zhao Su-Ling  , Zhang Fu-Jun  , Huang Jin-Ying  , Yan Guang  , Li Jun-Ming
Published: December 2020

A solid state cathodoluminescence (SSCL) device in which Si3N4 acts as the electronic accelerating layer and poly (2-methoxy-5-(2-ethyl-hexyloxy)-1， 4-phenylene vinylene (MEH-PPV) as the luminescent layer is first designed. Under alternating current bias， SSCL of MEH-PPV is realized. The luminescence peak is located at 600 and 417nm， respectively, corresponding to the exciton emission and the recombination luminescence of lowest unoccupied molecular orbital (LUMO) to highest occupied molecular orbital (HOMO). The intensity of the twopeaks changes with the increasing of the driving voltage nonlinearly. Compared with the device with SiO2 as the accelerating layer， the short wavelength emissions are found to be the same and located at 417nm for both devices, although their accelerating layers are different. It confirms the SSCL theory and the short wavelength is caused by the direct recombination of electrons in LUMO and holes in HOMO. Finally， the accelerating abilities of Si3N4 and SiO2 are compared at high driving voltage, which showed that the accelerating ability of SiO2 is superior to that of Si3N4 at the driving voltage involved.
Thermoluminescence and optically stimulated luminescence characteristics of α-Al2O3：C crystal
Authors: Yang Xin-Bo  , Li Hong-Jun  , Xu Jun  , Cheng Yan  , Su Liang-Bi  , Tang Qiang
Published: December 2020

In this work，α-Al2O3：C crystal was grown by temperature gradient technique using α-Al2O3 and graphite powder as raw materials， and the thermoluminescence (TL) and optically stimulated luminescence (OSL) of the crystal were investigated by Ris TL/OSL-DA-15. The as-grown α-Al2O3：C crystal shows a single TL peak at 462K and blue emission peak at 410nm. The TL intensity increases as irradiation dose increases， but no shift is found in the position of the glow peak. The OSL decay curve of α-Al2O3：C crystal consists of two components， namely the fast component and the slow component. With the increasing of the dose，the decay rate of the fast component almost remains unaltered while that of theslow component increases. The TL response of the crystal shows excellent linear characteristic in the dose range of 5×10-6—10Gy， and saturation is observed at 30Gy. The OSL response shows excellent linear characteristic in the dose range of 5×10-6—60Gy， and reaches saturation at 100Gy. Compared with TL response， OSL response shows higher sensitivity and wider linear dose response.
Ablating of carbon nanotube by laser beam and its effect on field emission performance
Authors: Zheng Xin-Liang  , Li Guang-Shan  , Zhong Shou-Xian  , Tian Jin-Shou  , Li Zhen-Hong  , Ren Zhao-Yu
Published: December 2020

Carbon nanotubes (CNTs) cathodes have been made by using screen-printing. Conglutinated CNTs were separated after ablation by laser beam. The spacing between CNTs is increased， the screen effect is diminished. Experiment results show that the field emission properties of CNTs film are highly improved， the relevant turn-on voltage was reduced and the field enhancement factor β was enhanced. From Raman spectra of multi-wall CNT films treated by laser ablation， the defects on CNT surface were increased with increasing laser energy， and became new field emission dots. Compared with diode structure, the flat gate structure showed better field emission performance. So the laser ablation is an effective method that could enhance CNT field emission properties， and has value in the research of CNT cathode materials. At the same time， the flat gate structure has better prospects in the structure design of CNTs field emission flat display.
First principles study on substitution behaviour of Si in TiAl3
Authors: Zhu Guo-Liang  , Shu Da  , Dai Yong-Bing  , Wang Jun  , Sun Bao-De  ,   上海交通大学金属基复合材料国家重点实验室，上海  200240
Published: December 2020

The site preference of Si in TiAl3 is calculated by using a first principles method based on density functional theory. The analyses of the c/a value， the formation energy and density of states of systems with different substitution behaviours show that Si prefers to occupy the Al site. The site preference is primarily determined by the electronic structure， and the calculated result is in good agreement with the experimental result. In order to further study the site preference， the occupied sites are divided into two different distributions， the loose distribution and the compact distribution. The calculations of total energy， the formation energy and density of states of systems indicate that Si has a preference for Al（2） sites with a loose distribution. When the systems with Al（2） sites are substituted， the value of c/a increases with doped Si concentration increasing， which is opposite to the case where Al（1） sites are substituted. The study also indicates that the limited solubility of Si in TiAl3 lies between 12.5at% and 18.75at%.
Effects of B and N doping on spin polarized transport in graphene nanoribbons
Authors: Zheng Xiao-Hong  , Dai Zhen-Xiang  , Wang Xian-Long  , Zeng Zhi  ,   中国科学院固体物理研究所材料物理重点实验室，合肥  230031
Published: December 2020

First principles calculations are performed to study the spin polarized transport in zigzag-edged graphene nanoribbons with anti-ferromagnetic ordering. It is found that when a single B or an N atom is doped in the central scattering region, their effects on the different spin components of current are completely different, though they play the same role in reducing the magnetic moments of the edge carbon atoms. In the B doping case, the spin-up component in current is much larger than the spin-down component, while the situation is opposite to the N doping case. This originates from the fact that the spin degeneracy is broken and the spin-up energy levels in the valence band and the conduction band are higher than the spin-down energy levels in both cases. B doping introduces a hole so that the fully filled valence band becomes partially filled and the Fermi level shifts down to the spin-up energy levels in the valence band while the spin-down energy levels in it are a little far from the Fermi level. This strengthens the transmission of electrons in the spin-up channel more than it does for the spin-down electrons. N doping introduces an electron which makes the empty conduction band partially filled so that the Fermi level shifts up to the spin-down energy levels in the conduction band. This strengthens the transmission of electrons in the spin-down channel more than it does for the spin-up electrons.
A thermo-elastoplastic constitutive equation including phase transformation and its applications
Authors: Chen Bin  , Peng Xiang-He  , Fan Jing-Hong  , Sun Shi-Tao  , Luo Ji  ,   重庆大学资源及环境科学学院，重庆   400044
Published: December 2020

Heat-processed materials undergoing phase transformation are considered to be a mixture of several phases, and each of them possesses thermo-elastoplastic property. A thermo-elastoplastic constitutive equation involving phase transformation is put forward based on the physics of continuous media and the irreversible thermodynamics with internal variables. The material parameters in the constitutive equation and their variations with temperature are determined by a series of short-time-tension tests at different temperatures. The heat conduction equation including phase transformation and the transformation kinetics equation including stresses are also presented. The numerical algorithm and the finite element procedure related to these equations are developed and applied to the investigation of the distribution of the residual stress in the welding slot area of 1Cr12WMoV stainless steel pipe. The obtained results of the residual stress are in good agreement with the measurements by X-ray diffraction.
Effect of surface reflectances on the space-based vector radiative detection
Authors: Cheng Tian-Hai  , Gu Xing-Fa  , Yu Tao  , Chen Liang-Fu  , Tian Guo-Liang  ,   (1)中国科学院遥感应用研究所,遥感科学国家重点实验室,北京  100101；国家航天局航天遥感论证中心,北京  100101; (2)中国科学院遥感应用研究所,遥感科学国家重点实验室,北京  100101；中国科学院研究生院,北京  100049；国家航天局航天遥感论证中心,北京  100101
Published: December 2020

The propagation and redistribution of radiation in surface-atmosphere medium can be fully described by vector radiative transfer equation, which is the basis of quantitative remote sensing. How to deal with the questions of multiple-scattering effect, the polarization effect of the scattered radiation and the surface reflectance model is essential to an accurate simulation of vector radiative transfer equation, which affects the precision of quantitative remote sensing. This paper solves the vector equation of radiative transfer by using the successive orders of scattering approach; it includes the bidirectional reflectance distribution function （BRDF） model and bidirectional polarized reflectance distribution function （BPDF） model of surface reflectance. The index of relative errors was used to quantitatively study the effect induced by the difference of surface reflectance models and the polarization effect. Based on the studies, the basic theory of quantitative remote sensing using vector radiative transfer equation is proposed.
A piecewise-linear Sprott system and its chaos mechanism
Authors: Chen Jian-Jun  , Yu Si-Min  ,   广东工业大学自动化学院,广州  510006
Published: December 2020

In this paper, a piecewise-linear Sprott system is proposed and its chaos mechanism is analyzed. According to the Shilnikov theorem, on the condition that the basic characteristics of heteroclinic orbit, Shilnikov inequality and eigenvalue equation are satisfied, by finding a heteroclinic orbit formed by three geometric invariant sets, namely the unstable manifold, heteroclinic point, and stable manifold, a set of real parameters in accordance with the condition of existence of heteroclnic orbit are obtained for this chaotic system. Thus, the existence of heteroclnic orbit has been proved. Finally, according to this set of real parameters, the circuit design and experimental verification has been carried out.
Formation and thermal stability of compound stucture of carbon nanotube and silicon nanowire
Authors: Meng Li-Jun  , Xiao Hua-Ping  , Tang Chao  , Zhang Kai-Wang  , Zhong Jian-Xin  ,   (1)湘潭大学量子工程与微纳能源技术研究所,湘潭  411105; (2)湘潭大学量子工程与微纳能源技术研究所,湘潭  411105；湘潭大学物理系,湘潭  411105
Published: December 2020

We have studied the formation process of carbon nanotube-silicon nanowire compound structures by using empirical molecular dynamics method and their thermal stability by empolying Lindemann index. Our results show that, in some cases, liquid Si encapsulated in C（13,0） and C（14,0） carbon nanotubes can crystallize into nanowires composed of linked Si16 and Si20 fullence cages, respectively. The Si nanowire inside the carbon nanotube has higher melting temperature then the Si nanowire in free space. By calculating interaction potential energy between SiNW clusters and carbon nanotubes with different diameters, we have found that the radial stress on Si20NW induced by the carbon nanotube can increase melting temperature of Si20NW. For Si20NW under free boundary condition, this radial stress can be released by the deformation of Si20NW which results in decrease of the melting temperature of Si20NW cluster.
Two-bubble interaction under the sound field
Authors: Zhang Peng-Li  , Lin Shu-Yu  ,   陕西师范大学应用声学研究所,西安  710062
Published: December 2020

The paper established the motion equation of two-bubble walls under the sound field, and obtained the resonant frequency, vibration radius and radiation pressure of the double-bubble cavitation. From the frequency equation, radius of vibration and sound pressure equation we can see that the movement of two-bubble is different from a single bubble. Resonance frequency, resonance amplitude and radiation pressure are related to the distance between the bubble. By carrying out the numerical solution by MATLAB, we found that the resonance frequency and amplitude resonance increased with the distance between the two-bubble.
First-principles study on 3C-SiC(001)-(2×1)surface atomic structure and electronic structure
Authors: Liu Fu  , Zhou Ji-Cheng  , Tan Xiao-Chao  ,   中南大学物理科学与技术学院,长沙  410083
Published: December 2020

We calculate the atomic and electronic structure of 3C- SiC（001）-（2×1） using density functional calculations within the generalized gradient approximation. The calculated results show that the atomic structure of 3C-SiC（001）-（2×1） surface can be described by dissymmetrical Si dimmer model. The bond length of Si dimmer of 3C-SiC（001）-（2×1） surface is 0.232 nm. The calculated results of electronic structure show that a prominent density of states exists at the Fermi level, so the 3C-SiC（001）-（2×1） surface has the characteristics of metal. There are four surface state bands in the gap, one of which is located near the Fermi level, another at 5 eV above Fermi level, and the others in the valence bands below Fermi level.
The in situ two-temperature process of preparation of CeO2 films on sapphire substrates and technical improvements of fabrication of Tl-2212 films
Authors: Xie Qing-Lian  , Wang Zheng  , Huang Guo-Hua  , Wang Xiang-Hong  , You Feng  , Ji Lu  , Zhao Xin-Jie  , Fang Lan  , Yan Shao-Lin  ,   (1)广西师范学院物理与电子工程学院, 南宁  530001; (2)广西师范学院物理与电子工程学院, 南宁  530001；南开大学信息技术科学学院电子信息科学与技术系,天津  300071; (3)南开大学信息技术科学学院电子信息科学与技术系,天津  300071
Published: December 2020

The preparation of CeO2 buffer layers on r-cut sapphire substrates by in situ two-temperature process and Tl-2212 superconducting films has been studied. The results of XPS and AFM show that this simple process of growing buffer layer produces CeO2 film with smooth surface, which can hold back the diffusion of Al from sapphire into Tl-2212 film. The 530 nm thick Tl-2212 films grown on the CeO2 buffer layers subsequently possess excellent electrical property. The films have a high transition temperature （Tc =108.2 K）, a high critical current density （Ｊc=6.58 MA/cm2at 77 K and zero applied magnetic field） and a low surface resistance （Rs=185 μΩ at 10 GHz and 77 K）, and their superconductivity can be improved significantly.
First-principles calculation of microwave dielectric properties of Al-doping ZnO powders
Authors: Huang Yun-Xia  , Cao Quan-Xi  , Li Zhi-Min  , Li Gui-Fang  , Wang Yu-Peng  , Wei Yun-Ge  ,   西安电子科技大学技术物理学院,西安  710071
Published: December 2020

The band structure and dielectric properties of the pure ZnO and the Al-doped ZnO were studied by using a first-principle ultrasoft pseudopotential approach of the plane wave based on the density functional theory. The pure ZnO and the Al-doped ZnO powders were prepared via the solid state reaction at 600°C with holding time of 1.5 h. The prepared powders were characterized by X-ray diffraction （XRD） and X-ray photoelectron spectroscopy （XPS）. The dielectric parameters were determined by the vector network analyzer in the frequency range of 8.2—12.4 GHz. Results show that the volume of super-cell has no obvious change and the Fermi energy level is introduced into conduction band through introducing Al ions. XRD patterns indicate that all the samples have pure wurtzite structure of ZnO. It is found that Al ions form the substitutional impurity in ZnO crystal according to the result of XPS. The experimental results show that both the real part ε′ and imaginary part ε″ of permittivity of the samples are increased by Al doping, in agreement with the result of calculation.
Numerical simulation of three-dimensional dendritic growth using phase-field method
Authors: Zhu Chang-Sheng  , Feng Li  , Wang Zhi-Ping  , Xiao Rong-Zhen  ,   (1)兰州理工大学甘肃省有色金属新材料省部共建国家重点实验室,兰州  730050; (2)兰州理工大学甘肃省有色金属新材料省部共建国家重点实验室,兰州  730050；兰州理工大学CAD中心，兰州  730050
Published: December 2020

Quantitative numerical simulation of three-dimensional dendritic growth in pure undercooled melt is carried out based on phase-field model of thin-interface limit and incorporating interfacial energy anisotropy which is solved by an accelerated algorithm of the dynamic computing regions, the dendritic growth is faithfully described. The dendritic tip is analyzed by cutaway view, indicating that the anisotropy of main branches’ section is not more obvious than that of main branches. The dendritic tip growth speed, tip radius, tip Peclet number as well as classic stability parameter σ* are simulated, compared with reported values under same condition,and they agree well with each other. Dendritic growth law that is in accordance with crystalline theroy is achieved, and it is proved that it is feasible and effective to simulate three-dimensional dendritic growth using phase-field method.
First-principles study on the influence of component element substitution on the dehydrogenation ability of LiNH2 hydrogen storage materials
Authors: Zhang Hui  , Qi Ke-Zhen  , Zhang Guo-Ying  , Wu Di  , Zhu Sheng-Long  ,   (1)沈阳师范大学物理科学与技术学院，沈阳  110034; (2)中国科学院金属研究所金属腐蚀与防护国家重点实验室，沈阳  110016
Published: December 2020

The influence mechanism of element substitution on the dehydrogenation ability of LiNH2 was investigated by plane wave pseudo-potential method based on density functional theory. The binding energy, density of states （DOS） and overlap population were obtained by structure calculation, the stability of LiNH2 structure and the binding nature between atoms were analyzed. Results showed that the bond strength between N and H is reduced when the Li atoms of LiNH2 are partially replaced by the Ca, Na, or Al atoms. The best effect is get by Al, Mg co-doping. The N atoms of Li（Mg）NH2 are partially replaced by the B, C, or P atoms, the effect of C is best. It is predicted that a hydrogen storage material with lower desorption temperature can be obtained by Mg, Al, C substitution to Li, N of LiNH2.
Nonergodicity of Brownian motion in a periodic potential
Authors: Lu Hong  , Qin Li  , Bao Jing-Dong  ,   北京师范大学物理系，北京  100875
Published: December 2020

Nonergodicity in Brownian dynamics can be divided into two classes by adding a periodic potential in a force-free ballistic diffusive system. Class-Ⅰ is the system in which the Laplace transform of the damping kernel is equal to zero at low frequency. When the temperature is much higher than the barrier height, the kinetic part of the mean energy depends on the initial distribution of the velocity; with the temperature decreasing, the ergodicity is recovered. Thinking the stable velocity variance of class-Ⅰ as an internal noise to drive a force-free Brownian particle, the Laplace transform of the damping kernel is infinite at zero frequency. It is found that the diffusion coefficient approaches vanishing with the temperature increasing, which exhibits the characteristic of classical locality. The asymptotic mean-square coordinates of the class-Ⅱ depends on its initial coordinates and the ergodicity cannot be ensured through introducing a potential.
Dynamics of relaxation oscillation caused by stimulated Brillouin scattering in optical fiber and its suppression
Authors: Yin Jing-Chan  , Xiao Xiao-Sheng  , Yang Chang-Xi  ,   清华大学精密仪器与机械学系，精密测试技术与仪器国家重点实验室，北京  100084
Published: December 2020

In order to further study the dynamics of relaxation oscillation during stimulated Brillouin scattering （SBS） and to avoid optical damage caused by SBS under high power lasers in applications such as fiber amplifier and fiber phase conjugate mirror，etc.，the dynamics of relaxation oscillation during SBS in fibers are studied on the basis of the SBS coupled amplitude equations using numerical simulations of finite difference methods. Meanwhile，we propose a method to suppress the relaxation oscillation. For different rise time of SBS pump pulse，the temporal and spatial variation of intensities of pump and Stokes waves is plotted as three-dimensional figures. The corresponding experiments have been conducted and the experimental results agree well with the theoretical results. From the experiments and numerical calculations it can be concluded that，by increasing the rise time of SBS pump pulse the relaxation oscillation can be suppressed effectively and the optical damage caused by SBS can be avoided consequently.
Mechanical anti-aliasing acoustic low-pass filtering fiber-optic hydrophones with side cavities
Authors: Wang Ze-Feng  , Hu Yong-Ming  , Meng Zhou  , Luo Hong  , Ni Ming  ,   国防科学技术大学光电科学与工程学院，长沙  410073
Published: December 2020

A novel mechanical anti-aliasing fiber-optic hydrophone with an acoustic low-pass filter of side cavities has been reported，to the best of our knowledge，for the first time. The low frequency lumped parameters model and the effective acoustic circuit of the hydrophone is constructed based on the theories of electro-acoustic analogy，and the acoustic performance is predicted by the circuit analysis methods. Theoretical results show that the hydrophone has three resonant frequencies and one inverse resonant frequency induced by the side cavities，and the hydrophone has good high frequency attenuation properties. A hydrophone with side cavities，designed and fabricated by us，is tested in a standing-wave tube filled with water. The measured frequency response curve，on the whole，has identical form as that predicted by theory, over the test frequency range of 50 to 7000 Hz. To be speaific，the low frequency responses are in good accordance，and the acoustic sensitivity is about -140 dB re 1 rad/μPa. The high frequency responses have obvious difference，which is mainly induced by the operation limitation of the low frequency model. It is expected that this new type of fiber-optic hydrophone will work as an important class of sensors used to eliminate the aliasing in the future fiber-optic sonar systems.
Laser induced bubble characteristics with experimental and numerical methods
Authors: Wang Yu-Hong  , Wang Jiang-An  , Ren Xi-Chuang  ,   海军工程大学电子工程学院,武汉  430033
Published: December 2020

According to the characteristics that a laser induced bubble is filled with mostly water vapor and a little noncondensable gas, a specific Rayleigh-Plesset equation which was used to determine the position of the dynamic bubble wall and other concerned conditions were used. Mass diffusion between the bubble and the gases dissolved in surrounding water, compression of water, condensation and evaporation at the bubble wall, heat conduction, sound radiation, viscosity of water and surface tension were considered. A laser induced bubble producing, photographing and pressure measuring system was set up. Numerical and experimental method was used; the relative error of pressure inside bubble was under 10%. The relations were showed among the absorbed laser puergy, the pressure and the temperature in the bubble and the bubble radius.
Three-dimensional cavitation simulation using lattice Boltzmann method
Authors: Zhang Xin-Ming  , Zhou Chao-Ying  , Islam Shams  , Liu Jia-Qi  ,   (1)哈尔滨工业大学深圳研究生院,深圳  518055; (2)哈尔滨工业大学数学系,哈尔滨  150001
Published: December 2020

The cavitation is a complex phenomenon which is microcosmic, transient, stochastic and multiphased. The extreme condition and related cavitation effects which the collapsed cavities generate will affect the liquid-vapor system greatly. In this article, we accurately simulate heterogeneous cavitation in liquid system with single component multiphase lattice Boltzmann model and successfully reproduce the complete cavitation process of a bubble: inception, growth and collapse. The relationship between the radius of bubble seed and cavitation for a specified tension has been investigated by lattice Boltzmann method simulations. The simulations show excellent agreement with energy considerations based on interface formation and bubble expansion.
Experimental study of large power lower hybrid current drive on HT-7 tokamak
Authors: Xu Qiang  , Gao Xiang  , Shan Jia-Fang  , Hu Li-Qun  , Zhao Jun-Yu  ,   中国科学院等离子体物理研究所，合肥  230031
Published: December 2020

Large power current drive of lower hybrid wave （LHW） was performed （PLHW 100—800 kW at 2.45 GHz） recently in the HT-7 tokamak. The lower hybrid current drive （LHCD） efficiency is studied for different injected powers and for different densities. Improved particle confinement is observed by application of LHCD as characterized by an increase of central line average electron density and decrease of Dα emission. The particle confinement time τp increased about 1.5 times compared with ohm discharge. The dependence of energy confinement time τE on plasma density and LHW power is experimentally studied in detail.
Energy dissipation mechanism of phononic friction
Authors: Ding Ling-Yun  , Gong Zhong-Liang  , Huang Ping  ,   华南理工大学机械与汽车工程学院，广州  510640
Published: December 2020

Focusing on the interfacial friction, the energy accumulation and dissipation mechanisms are analyzed in the present paper. Based on the lattice thermokinetics theory, the potential difference of interfacial atom during the jumping process is calculated, then the formula of interfacial temperature rise is deduced successfully. The analysis indicates that the interfacial temperature depends on the contact status and material properties of the friction system, and the interfacial interactive potential is an important factor. In the initial stage of slipping process, as the interfacial atoms are in the non-equilibrium thermal state, new phonon are excited to enable the friction energy dissipation, which finally makes the non-thermal equilibrium transit to equilibrium state. Based on the quantum mechanics and the thermodynamics, the energy dissipation mechanism of interfacial friction is studied. The results show that the elastic potential energy stored during the sticking process dissipates more quickly with higher vibration frequency, and the dissipation time is much shorter than the slip time in one cycle.
Negatively charged exciton on the quantum ring
Authors: Wu Hong  ,   集美大学物理系，厦门  361021
Published: December 2020

In this paper, the energy-optical spectra and their Aharonov-Bohm oscillation of the negatively charged exciton are studied. A negatively charged exciton is composed of three charge particles, electrons and hole, the number of basic wave functions （basic vectors） which compose the state wave functions are large, so the numerical computing work is quite tedious. So far, many authors usually separate the spatial wave function into motion of mass centre and relative motion parts to save the numerical computing time. There is considerable discrepancy in the results of this method. It only suits the case when the external magnetic field is very weak. Considering the conservation of angular momentum, in case that there is no external electric field, we classity the whole set of basic vectors according to the values of their total orbital angular momentum. Then starting from Hamiltonian directly, we propose an alternative computing method to find the eigen values and eigen functions of the system. Our method can save more than 90% of computer time. There is no so called diamagnetic shift in our results. Our results fit well with the experimental data. The effects of the radii of the quantum ring, the value of dielectric constant and the effective mass of hole on the energy-optics spectra are systematically discussed.
High mobility polymer thin-film transistors
Authors: Liu Yu-Rong  , Wang Zhi-Xin  , Yu Jia-Le  , Xu Hai-Hong  ,   (1)华南理工大学电子与信息学院，广州  510640; (2)华南理工大学应用物理系，广州  510640
Published: December 2020

Polymer-based thin film transistors （PTFTs） were successfully fabricated on silicon substrates which was used as gate electrode, thermal silicon dioxide was used as gate insulators and poly（3-hexylthiophene） as semiconducting active layers for the transistors. The fabrication and measurement of the devices were all performed in the clean air. The PTFTs with a surface-modified gate insulator show better electric characteristics with the field-effect mobility of 0.02 cm2/（Vs） and the on/off ratio higher than 105.
Evaporation induced solidification of cyclohexane drops under acoustic levitation condition
Authors: Du Ren-Jun  , Xie Wen-Jun  ,   Department of Applied Physics, Northwestern Polytechnical University, Xi’an 710072, China
Published: December 2020

The evaporation process of a cyclohexane drop is investigated by single-axis acoustic levitation method. It is found that the evaporation of the cyclohexane drop results in the decrease of its temperature below the melting point, and leading to solidification. The real-time observation with a high speed camera shows that the cyclohexane nucleates near the equator of the drop surface and grows dendritically with an average velocity ranging from 12.5 to 160.4 mm/s. Further studies indicate that the ratio Sh/Nu of the average Sherwood number to Nusselt number under acoustic levitation condition is 1.3 times of that under natural convection condition. This suggests that the acoustic streaming boundary layer effectively strengthens the evaporation but has less promotion effect on the heat transfer. Therefore, the drop temperature declines to a lower value and the evaporation induced solidification occurs under acoustic levitation condition. Accordingly, a necessary condition for the occurrence of evaporation induced solidification of volatile liquids is proposed.
Experimental method of measuring sound velocity using ultrasonic flowmeter
Authors: Wang Xin-Feng  , Xiong Xian-Chao  , Gao Min-Zhong  ,   Test and Launch Station, Jiuquan Satellite Launch Center of China, Jiuquan 732750, China
Published: December 2020

In order to obtain sound velocity in liquid, an experimental method of measuring sound velocity is designed. A time-difference type ultrasonic flowmeter and normal flow checkout equipment are used to measure the flow speed of liquid in closed hydraulic pipeline simultaneously, then the measured value and the true value of the flow rate are measured, and the meter-factor of the ultrasonic flowmeter is determined. Furthermore, the relationship between the sound velocity and the meter-factor is derived under a certain condition. Based on the method, the velocity of sound in dinitrogen tetroxide (N2O4) at 7.6-19.4 ℃ and unsymmetric dimethyl hydrazine ((CH3)2NNH2) at 6.5-25.2 ℃ are measured at 0.17 MPa. It provides reference for measuring the sound velocity in other liquid.
Hologram pressure field weighted norm extrapolation method
Authors: Xu Liang  , Bi Chuan-Xing  , Wang Hui  , Xu Bin  , Chen Xin-Zhao  ,   Institute of Sound and Vibration Research, Hefei University of Technology, Hefei 230009, China;,   Institute of Intelligent Machines, Chinese Academy of Sciences, Hefei 230031, China
Published: December 2020

Hologram pressure extrapolation is a key process of Patch nearfield acoustic holography. In this paper, a pressure extrapolation method based on the weighted norm extrapolation is proposed, in which the auto-power spectrum of hologram pressure estimated by the measured data is used as a weighting function to build the weighted norm, and the hologram pressure extrapolation is realized by minimizing the weighted norm. Because both the spectrum shape and the bandwidth information about hologram pressure are utilized during the extrapolation, a more accurate extrapolated result can be achieved. The validity of the proposed method is proved by a numerical simulation and an experiment study. The simulation results show that the proposed method has obviously advantages in accurcy and computational efficiency compared with the classic wave number domain extrapolation method. Furthermore, the proposed method is used to extrapolate a pressure field generated by a camped steel plate in experiment and a satisfactory result is obtained.
Thermal conductivity of mesoporous material MCM-41
Authors: Huang Cong-Liang  , Feng Yan-Hui  , Zhang Xin-Xin  , Wang Ge  , Li Jing  ,   Department of Thermal Engineering, University of Science and Technology, Beijing 100083,China;,   School of Materials Science and Engineering, University of Science and Technology, Beijing 100083,China
Published: December 2020

In this paper, the mesoporous structural unit of MCM-41 is established first and the equilibrium molecular dynamics (EMD) numerical simulation is performed to obtain the shell thermal conductivity of MCM-41. Then, based on one-dimensional heat transfer analysis, the analytical expression for effective thermal conductivity of MCM-41 is obtained by coupling heat conduction in air-filled nano-pores and that in the shell. The effects of wall thickness, pore size and porosity on the thermal conductivities of the MCM-41 are further analyzed. It turns out that MCM-41 possesses good thermal insulation and the decrease of effective thermal conductivity is closely linear as porosity increases. Furthermore, the thermal conductivity shows that it is obviously anisotropic and its largest value is along the length of the pores, and that it has the quasi-one-dimensional characteristic.
Effects of gradient disorder on electronic transport in quasi-one-dimensional nanowires
Authors: Duan Ling  , Hu Fei  , Ding Jian-Wen  ,   Department of Physics, Institute of Nanophysics and Rare-earth Luminescence, Xiangtan 411105, China;,   Key Laboratory of Low Dimensional Materials and Application Technology, Xiangtan University, Xiangtan 411105, China
Published: December 2020

Considering both the gradient decay of the real disorder and the contact scattering, we investigate the electronic transport in quasi-one-dimensional nanowires by developing a decomposition elimination method for Green's function matrix. In the presence the contact scattering, the conductance oscillates with energy. For some energies of incident electrons, an abnormal enhancement is obtained in the average conductance due to the destroyed coherence by the introduction of much low disorder, showing that there appears a new conductance peak. In the absence of disorder gradient, the average conductance firstly decreases then increases with disorder strength, indicating that there exists a localization-delocalization transition. In the presence of linearly decaying disorder, the average conductance increases slightly in a strong disorder region. In the case of the Gaussian-type decaying disorder, the average conductance decreases exponentially and the localization-delocalization transition disappears, which is different from previous thereotical result. The results are helpful for the design and the application of quasi-one-dimensional nanowires device.
Effects of end groups on the rectifying performance in D-B-A molecular rectifiers
Authors: Guo Chao  , Zhang Zhen-Hua  , Pan Jin-Bo  , Zhang Jun-Jun  ,   School of Physics and Electronic Science, Changsha University of Science and Technology, Changsha 410004, China
Published: December 2020

Using the density-functional theory and the non-equilibrium Greens function method, we investigate the electronic transport properties and rectifying performances of four different molecular devices based on different end groups from the same D-B-A molecule. The results show that the end groups can significantly affect the rectifying performances of such molecular rectifiers, because the end groups can influence the coupling effects between the molecule and the electrodes, thus changing the delocalization of molecular orbitals, and further changing their transport properties and rectifying performances. More interestingly, it is found that the rectifying directions and working mechanism for all of our studied systems are in disagreement with ones proposed originally by Aviram and Ratner. This property can be rationalized through the asymmetric shift of molecular levels under biases of different polarities.
High electron mobility lattice-matched InAlN/GaN materials
Authors: Zhang Jin-Feng  , Wang Ping-Ya  , Xue Jun-Shuai  , Zhou Yong-Bo  , Zhang Jin-Cheng  , Hao Yue  ,   Key Laboratory of Wide Band Gap Semiconductor Materials and Devices, School of Microelectronics, Xidian University, Xi'an 710071, China
Published: December 2020

InAlN can be in-plane lattice matched (LM) to GaN, and the formed InAlN/GaN heterostructure is one kind of materials with high conductivity to be used in GaN-based high electron mobility transistors (HEMTs). It is reported that the high-mobility InAlN/GaN material is grown by using pulsed metal organic chemical vapor deposition (PMOCVD) on sapphire, and the Hall electron mobility reaches 949 and 2032 cm2/Vs at room temperature and 77 K, respectively. The two-dimensional electron gas (2DEG) is formed in the sample. When 1.2 nm thick AlN space layer is inserted to form InAlN/AlN/GaN structure, the Hall electron mobility increases to 1437 and 5308 cm2/Vs at room temperature and 77 K, respectively. It is shown by analyzing the results of X-ray diffraction and atomic force microscopy and the features of PMOCVD that the crystal quality of InAlN/GaN material is quite high, and the InAlN layer LM to GaN has smooth surface and interface. The high mobility characteristics of InAlN/GaN and InAlN/AlN/GaN materials are ascribed to the fact that the 2DEG has a comparatively low sheet density (1.61013-1.81013 cm-2), the alloy disorder scattering is weakened in the high-quality InAlN crystal since its compositions are evenly distributed, and the interface roughness scattering is alleviated at the smooth interface where the 2DEG is located.
Improvement of resistive switching in Ti/Pr0.7Ca0.3MnO3/La0.67Sr0.33MnO3/Pt heterostructures
Authors: Wang Zhong-Wei  , Zhang Jian  , Wei Dong  , Ying Zhao  , Jing Zhao  , Xu Chen  ,   College of Physics Science and Information Engineering, Hebei Normal University, Department of Physics and Hebei Advanced Thin Film Laboratory, Shijiazhuang 050024, China
Published: December 2020

Ti/Pr0.7Ca0.3MnO3/Pt and Ti/Pr0.7Ca0.3MnO3/La0.67Sr0.33MnO3/Pt heterostructures are prepared using a pulsed laser deposition (PLD) technique, and the resistive switching of the heterostructures is investigated. The Ti/Pr0.7Ca0.3MnO3/La0.67Sr0.33MnO3/Pt heterostructure, which has a La0.67Sr0.33MnO3 modulation layer, shows superior characteristics of resistive switching. In particular, the switching ratio and the fatigue properties are improved greatly in this heterostructure. The mechanism of resistive switching in Ti/Pr0.7Ca0.3MnO3/La0.67Sr0.33MnO3/Pt heterostructure is also discussed in this paper.
Room-temperature ferromagnetism observed in Si-Al2O3 composite film
Authors: Zheng Yu-Long  , Zhen Cong-Mian  , Ma Li  , Li Xiu-Ling  , Pan Cheng-Fu  , Hou Deng-Lu  ,   Hebei Advanced Thin Films key Laboratory, Department of Physics, Hebei Normal University, Shijiazhuang 050016, China
Published: December 2020

Room-temperature ferromagnetism (FM) is observed in Si-Al2O3 amorphous composite film. The magnetic moment is the highest in the case of the Si-Al2O3 composite films with the Si content being 15 vol.%, and distinct domains are detected in our films. The difference in magnetism property between sample annealed in Ar atmosphere and untreated composite film indicates that the observed ferromagnetism does not originate primarily from oxygen defects. It is concluded that the ferromagnetism arises from the direct coupling between defects. These defects orignate from the interface between Si particles and Al2O3 matrix. By varying the Si content in the film, one can change the defect density and thereby control the strength of the ferromagnetic coupling.
Design and manufacture of high dispersion mirror
Authors: Wang Yan-Zhi  , Shao Jian-Da  , Dong Hong-Cheng  , Jin Yun-Xia  , He Hong-Bo  , Yi Kui  , Fan Zheng-Xiu  , Song You-Jian  , Wang Si-Jia  , Hu Ming-Lie  , Chai Lu  , Wang Qing-Yue  ,   Key Laboratory of Materials for High Power Laser, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China;,   Graduate School of Chinese Academy of Sciences, Beijing 100049, China;,   Ultrafast Laser Laboratory, College of Precision Instruments and Opto-electronics Engineering, Key Laboratory of Opto-electronic Information Science and Technology of Ministry of Education, Tianjin University, Tianjin 300072, China
Published: December 2020

The designed and manufactured high dispersion mirror combines the characteristics of chirped mirror and Gires-Tournois interferometer(GTI) mirror and provides high dispersion compensation with about -800fs2 GDD in a wavelength range of 780-830 nm and about -2500fs2 GDD in a wavelength range 1030-1050 nm, respectively. The dispersion mirror is manufactured by ion beam sputtering. The performance of the mirror has reached the designed values and can compensate the normal dispersion from ultrafst laser system effectively.
Fiber-coupled laser-driven flyer plates experiments
Authors: Zhao Xing-Hai  , Zhao Xiang  , Gao Yang  , Xi Shi-Wei  , Su Wei  ,   Institute of Electronic Engineering,China Academy of Engineering Physics,Mianyang 621900,China
Published: December 2020

A system for the launch of hypervelocity flyer plates is developed, characterized and applied. Laser-driven flyers are launched from substrate backed aluminum-alumina- aluminum sandwiched films. A laser-induced plasma is used to drive flyers with a thicknesses of a 5.5 m and a diameter of less than 1 mm, and typically, the flyer plates can achieve velocities of a few kilometers per second. These flyer plates have several applications ranging from micrometeorite simulation to laser ignition. The flyer plates considered here have three layers: an ablation layer for forming plasma; an insulating layer; and a final thicker layer for forming the final flyer plate. The optical fiber delivery system determines the spatial profile of the laser spot and power capacity. A technique and procedure for coupling high power laser pulse into optical fiber is developed. The surface finish of the fiber is found to be a critical factor. This fiber optic system is successfully used to launch flyer plates. Measurements of the flyer performance including the mean velocities and planarity are made by an optical time-of-arrival (TOA) technique with using an optical fiber array probe. The flyer shows a good planarity and achieves an average velocity of 1.7 km/s. The relationship between flyer velocity and incident laser pulse energy is investigated.
Popularity based network statistical analysis in peer-to-peer application
Authors: Wang Jing-Xin  , Wang Yue  , Li Yi-Peng  , Yuan Jian  , Shan Xiu-Ming  , Feng Zhen-Ming  , Ren Yong  ,   Department of Electronic Engineering, Tsinghua University, Beijing 100084, China
Published: December 2020

There are rich statistical characteristics in a peer-to-peer (p2p) network. The more refined statistical characteristics still need further understanding. In this paper we define the popularity threshold of the resource, and abstract the user network based on the popularity threshold to reflect the refined structure characteristics. Through the emprical study of a workload from a dominant peer-to-peer file sharing system, we confirm that the user network based on the popularity threshold has more clear cluster features than the original network. With the popularity threshold of resource increasing, the clustering is more evident. The homoplasy of users within the same cluster is enhanced. The clustering accuracy is inproved. Furthermore, in this paper we extract the cluster fingerprints which can provide a high representation accuracy in low dimensions.
A modified optimal routing strategy based on random walk on complex networks
Authors: Wang Kai  , Zhou Si-Yuan  , Zhang Yi-Feng  , Pei Wen-Jiang  , Liu Qian  ,   School of Information Science and Engineering, Southeast University, Nanjing 210096, China
Published: December 2020

In our original contributions, we found that the time which a random walker spends in finding a given path is directly proportional to the continued product of the degrees of all the nodes which pass through the given path. In this paper, with our original contributions, we give a modified routing strategy to improve the capacity of the network when all nodes have the same packet-delivery rates. We define an average routing centrality degree of the node to analyze the traffic load on the node with different degrees, and then we analyze the transportation capacity by using the critical value of Rc, the average packet travel time, the average path length and the search information. Both theoretical and experimental results show that compared with the shortest path strategy and the efficient path strategy, the new strategy can enhance the network capability.
Remote sensing of atmospheric refractivity from field measurements of vertical receiver array
Authors: Zhao Xiao-Feng  , Huang Si-Xun  ,   Institute of Meteorology, PLA University of Science and Technology, Nanjing 211101, China
Published: December 2020

In this paper we put forward a possibility of refractive index profile retrieval using field measurements at an array of radio receivers through the variational adjoint approach. The derivation of the adjoint model begins with the electromagnetic parabolic equation for a smooth, perfectly conducting surface and horizontal polarization conditions. To deal with the ill-posed difficulties of the inversion, the regularization idea is introduced into the establishment of the cost function. Based on the variational assimilation idea, the retrieval iterative format is constructed. Numerical experiments demonstrate the feasibility of theoretic algorithm for refractivity estimation. However, using the split-step Fourier algorithm to solve the forward model and the adjoint model, the intrinsic error of the solutions will increase with the extension of the propagation range, which reduces the inversion accuracy at long distance propagation. Through adopting a good initial refractivity profile and introducing the background fields in the cost function the inversions could generally be improved.
Classification of Blazar objects based on Logistic regression model
Authors: Tang Jie  , Wu Xue-Bing  ,   Department of Physics, Shaanxi University of Technology, Hanzhong 723001, China;,   Department of Astronomy, Peking University, Beijing 100871, China
Published: December 2020

We collecte 205 Blazars (142 BL Lacertae objects and 63 flat spectrum radio quasars(FSRQs)),and investigate the correlation between the redshift, the fluxes in the radio band (5 GHz), optical (V band) , X-ray (1 keV), and the X-ray photon spectral index for the BL Lacertae objects and FSRQs by the correlation analysis and Logistic regression model. The results indicate that major influencing factors on Blazar object classification are the redshift, the fluxes in the radio band (5 GHz), and the X-ray photon spectral index. The derived equation is effective as a substantial criterion for Blazar objects classification, of which the accuracy is 91.2%. Our results strongly support the division of Blazar objects into BL Lacertae objects and FSRQs. We compare the properties of BL Lacertae objects and FSRQs from the fluxes in the optical (V band) and X-ray (1 keV), and find that BL Lacertae objects are not significantly different from FSRQs. The implications of these correlations, which support the evolutionary sequence of Blazar objects, are also discussed.