bluuebunny/crossref_metadata_2025 huggingface dataset:
Ultra-short ultra-intense laser guiding and its influence on electron acceleration
Authors: Wang Guang-Hui  , Wang Xiao-Fang  , Dong Ke-Gong  ,   Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China;,   Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

Simulations and analyses of ultra-short ultra-intense laser propagting in plasmas with uniform and parabolic density profiles, as well as the electron injection into the wake field and the electron spectra in the stable transmission state are performed by using a particle-in-cell code. Fixing the incident laser focal spot size but changing the plasma density in a range of (0.42)1019/cm3, comparative analyses are carried out of the evolutions of the laser beam spot during the propagation of the laser pulse in the plasmas with aforementioned two density profiles, with the normalized laser intensity ranging from 1 to 6. The results show that a plasma channel with a parabolic density profile can realize a good guiding of an ultra-short ultra-intense pulse, which is beneficial for high energy electron acceleration. However, at higher densities, self-guiding can be realized by relativistic self-focusing in uniform plasma, which is conducive to simplifying the experiment and to producing more accelerated electrons.
The physical characteristic study on luminance uniformity and temperature for power GaN LEDs chip
Authors: Chen Huan-Ting  , Lü Yi-Jun  , Gao Yu-Lin  , Chen Zhong  , Zhuang Rong-Rong  , Zhou Xiao-Fang  , Zhou Hai-Guang  ,   Department of Physics and Electronic Information Engineering, Zhangzhou Normal University, Zhangzhou 363000, China;,   Fujian Engineering Research Center for Solid-State Lighting, Department of Electronic Science, Xiamen University, Xiamen 361005, China
Published: December 2020

In this paper, we study the relationship among current density distribution, heat and temperature based on current continuity equation, ohm law and three-dimensional heat transfer model. The relationship between luminance distribution and current spreading of GaN blue light emitting diode (LED) is studied. Luminance distribution is proved to be an effective method of distinguishing the performance of current spreading. Because of the close relationship among temperature, luminance distribution and current density, a qualitative method of optimizing electrode structure and current spreading is proposed. With different currents and heat sink temperatures, the current non-uniformity and the luminance distribution of LED are analyzed. Temperature or current density crowding results in heat accumulation, increase of non-radiative recombination and the restriction of the emitting photons, hence thermal flux is an important factor influencing the luminance distribution. Through carrier transport mechanism, the reason for the temperature influence on luminance distribution is explained. Optimized contact electrode structure can improve current spreading and luminance uniformity, also considerably increase the reliability of high power LED.
Investigation of positron annihilation in Fe52Co34Hf7B6Cu1 amorphous alloy treated by intermediate frequency magnetic pulse
Authors: Zhang Yan-Hui  , Li Yan-Long  , Gu Yue  , Chao Yue-Sheng  ,   College of Science, Northeastern University, Shenyang 110004, China;,   College of Science, University of Science and Technology Liaoning, Anshan 114044, China
Published: December 2020

The effect of intermediate frequency magnetic pulse treatments on Fe52Co34Hf7B6Cu1 amorphous alloy prepared by melt-spun technique is investigated. The microstructure and structural defects of the treated specimens are investigated by TEM, Mössbauer spectroscopy and position annihilation lifetime spectra. The results show that the treated specimens by intermediate frequency magnetic pulse are partially crystallized, the content of the crystallization phase increases with the increase of the magnetic pulse frequency, and the crystalline volume fraction is 33.1% at a frequency of 2000 Hz. For the as-quenched amorphous alloy, the annihilation lifetime τ1 is 150.5 ps in the monovacancy-like free volume, and the relative intensity I1 is 77.7%. The annihilation lifetime τ2 is 349.7 ps in the microvoid, and the relative intensity I2 is 22.3%. With the increase of the magnetic pulse frequency, the values of τ1 and τ2 of the treated specimens decrease, I1 increases, I2 and τ decrease compared with the as-quenched amorphous alloy.
Brownian motion in a harmonic trap: magnetic tweezers experiment and its simulation
Authors: Ran Shi-Yong  ,   School of Physics and Electronic Information Engineering, Wenzhou University, Wenzhou 325035, China
Published: December 2020

The Brownian motion in a harmonic trap is studied by magnetic tweezers experiment and computer simulation. The results of the experiment and simulation validate the theory. Then the theory is used to analyze the experimental results including the effect of persistent length of DNA on the displacement distribution of the bead and the error in force measurements. It can be concluded that the variation of the persistent length affects more the Brownian motion along the DNA chain than in the other direction; under a small force, a considerable error of the force measurement will occur.
Detecting unstable periodic orbits from continuous chaotic dynamical systems by dynamical transformation method
Authors: Ma Wen-Cong  , Jin Ning-De  , Gao Zhong-Ke  ,   School of Electrical Engineering and Automation, Tianjin University, Tianjin 300072, China
Published: December 2020

Detecting unstable periodic orbits (UPOs) from chaotic dynamic systems is a challenging problem. For a large number of complex systems, we can collect some experimental time series data but cannot find theoretical models to describe them. Thus, detecting unstable periodic orbits from experimental data can help us understand the chaotic properties of physical phenomenon without using theoretical models. We, in this paper, first use the dynamical transformation (DT) algorithm to detect unstable periodic orbits from chaotic systems, and find that the original DT algorithm can detect the UPOs from the time series of chaotic discrete map, but it is infeasible for the time series from continuous chaotic flow. In this regard, we then propose an improved DT algorithm that is based on the Poincare section method to detect the UPOs from continuous chaotic flow. In particular, we transform the continuous flow data into discrete map time series in terms of Poincare section, and then detect unstable periodic orbits from the transformed discrete map time series. In addition, we take Rössler and Lorenz chaotic systems as examples to demonstrate the effectiveness of our proposed method.
Analytical model for acoustic multi-relaxation spectrum in gas mixtures
Authors: Zhang Ke-Sheng  , Wang Shu  , Zhu Ming  , Hu Yi  , Jia Ya-Qiong  ,   Department of Electronics and Information, Huazhong University of Science and Technology, Wuhan 430074, China
Published: December 2020

To identify the correlation between sound propagation and molecular multimode vibrational relaxation in polyatomic gas mixture, an analytical model that constructs acoustic multi-relaxation spectrum is presented. The frequency-dependent effective specific heat of gas is formulated from the micro view of vibrational mode energy transfer as well as the macro view of relaxation process due to vibrational-vibrational mode energy coupling. With the aid of the general relaxation equations of multimode vibrational energy transfer, the analytical expressions to calculate acoustic relaxation absorption and dispersion, which reflect both primary and secondary relaxation processes, are developed from the effective specific heat. The constructed absorption spectra of various gas mixtures, consisting of carbon dioxide, methane, nitrogen, and oxygen, accord with the experimental data very well. Especially, the peak errors of those results are less than 1%. Moreover, the simulation results illustrate that less than two single processes with higher strength appear generally in a multi-relaxation absorption spectrum. Compared with the existing models, the analytical model can directly obtain the analytical expressions of characteristic points in the relaxation spectrum of gas mixtures, which makes it advantageous to analyze the spectral characteristics qualitatively and quantitatively. Consequently, the model provides an effective approach to analyzing the relationship between sound propagation and molecular vibrational relaxation of gas mixtures.
Simulation of spectrum of doped Ar in indirectly driven implosion target
Authors: Qiao Xiu-Mei  , Zheng Wu-Di  , Gao Yao-Ming  , Ye Wen-Hua  ,   Institute of Applied Physics and Computational Mathematics, Beijing 100094, China
Published: December 2020

X-ray spectrum of tracer in ICF implosion target is usually used to infer electron temperature, density and mix of fuel. As the plasma in fuel is in non-local thermodynamic equilibrium (non-LTE), a line transfer code Alpha is developed. Taking the electron temperature and density provided by radiation hydrodynamic as input condition, atomic kinetics and radiation transfer equation are self-consistently solved with the detailed configuration atom (DCA) model. The opacity for specified frequency intervals is obtained, and X-ray spectrum in the image plane is also presented.As application of Alpha program, the spectrum of doped Ar in implosion target on SG Ⅱ laser facility is simulated. The effect of self-absorption of K α line is studied. And it is shown that self-absorption of K α line affects both the intensity and shape of the spectrum, and it should be considered in simulating X-ray spectrum of Ar. And as the spectrum of local thermodynamic equilibrium (LTE) simulation gives large intensity and different shapes compared with the non-LTE results, non-LTE simulation is necessary in such a simulation.
The influence of deuteration and helium-implantation on the surface morphology and phase structure of scandium thick film
Authors: Peng Shu-Ming  , Shen Hua-Hai  , Long Xing-Gui  , Zhou Xiao-Song  , Yang Li  , Zu Xiao-Tao  ,   Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900, China;,   Department of Applied Physics, University of Electronic Science and Technology of China, Chengdu 610054, China
Published: December 2020

The effects of deuteration and helium-implantation on the surface morphology and phase structure of scandium (Sc) thick film are investigated by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) methods. The preferred orientation of (002) crystal plane is observed for both films deposited on substrates of monocrystalline-silicon and polished-molybdenum. A great number of holes appear on surface after deuteration and the grain size of ScD2 is bigger than that of Sc, whereas a few ScD0.33/Sc grains with relatively small grain size retain inside crystal. The surface morphologies of scandium and scandium deuteride films are slightly affected by helium-implantation. The formation of helium bubbles with a preferred orientation in the crystal lattice of scandium and scandium deuteride, generated by the aggregation of ion-implanted helium, causes the corresponding diffraction peaks of scandium and scandium deuteride phase to shift towards smaller angles.
The influence of gate voltage on electron transport in the graphene field-effect transistor under strong laser field
Authors: Liu Jiang-Tao  , Huang Jie-Hui  , Xiao Wen-Bo  , Hu Ai-Rong  , Wang Jian-Hui  ,   Department of Physics, Nanchang University, Nanchang 330031, China;,   Key Laboratory of Nondestructive Testing (Ministry of Education), Nanchang Hangkong University, Nanchang 330063, China
Published: December 2020

The influence of gate voltage on electron transport in the graphene field-effect transistor under strong laser field is studied by using the finite-difference time-domain method. The perfect tunneling in graphene can be strongly suppressed by the strong laser field induced optical stark effect. This suppression depends not only on the laser field but also on the width and the height of the gate voltage. The electron transport through a non-square barrier is investigated. We find that a barrier with a small incline has little effect on the electron transport, but if the barrier has a large incline, the tunneling probability changes remarkably.
Spectroscopic and thermal properties of Yb doped CaF2-SrF2 laser crystal
Authors: Wu Ye-Qing  , Su Liang-Bi  , Xu Jun  , Chen Hong-Bing  , Li Hong-Jun  , Zheng Li-He  , Wang Qing-Guo  ,   Institute of Materials Science & Engineering, Ningbo University, Ningbo 315211, China;,   Key Laboratory of Transparent and Opto-Functional Advanced Inorganic Materials, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 201800, China
Published: December 2020

Yb: CaF2-SrF2 crystals are grown by Bridgman technique. The spectroscopic properties, thermal diffusion coefficients and thermal expansion coefficients at different temperatures are studied. Thermal conductivity at 300 K and thermal expansion coefficient are calculated. The absorption spectra, fluorescence spectra, thermal properties of crystals are analyzed by comparison method. The results show that the absorption and emission cross sections are larger in the high concentration SrF2 disordered crystal. And also the emission cross section is large and wide at 1040 nm in the Yb: CaF2-SrF2 (19%) crystal. It demonstrates that for different ratios of CaF2 and SrF2 in the disordered crystals, the spectroscopic properties are different. The main possible reason is the different disorders, low symmetry, low symmetry optical centers in the disordered crystal. It can also be seen that the disordered crystal has a good thermal conductivity.
The influence of ionization efficiency on the multiply charged ions produced by laser-clusters interaction
Authors: Qu Pi-Cheng  , Wang Wei-Guo  , Zhao Wu-Duo  , Zhang Gui-Qiu  , Li Hai-Yang  ,   College of Chemistry, Chemical Engineering and Materials Science, Shandong Normal University, Jinan 250014, China;,   State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China;,   Graduate School of Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

The productions of multiply charged ions in the interactions of intense nanosecond laser pulse with clusters have aroused broad interests in molecular physics. Benzene, cyclohexene and cyclohexane clusters are chosen to study the effect of multiphoton ionization (MPI) efficiency on the relative intensity of multiply charged ions, as they possess similar molecular structures and the same element constitutions. They are ionized with a 5 ns Nd-YAG nanosecond laser. The carbon charge state produced by cyclohexene and cyclohexane is about 4; while by benzene is only about 3. The ratios of C3+/C2+ for cyclohexane, cyclohexene and benzene are 1.1, 0.6 and 0.4, respectively. The relative MPI efficiencies of three molecules are measured to be in the magnitude sequence of benzene > cyclohexene > cyclohenane by diffusion beam. Higher MPI efficiency of molecules can cause more than one molecules to be ionized at the edge of laser pulse, the Coulomb repelling force between adjacent ions leads clusters to early split into small size ones, which will prevent the production of the highly charged ions.
Nonlinear absorption properties of Cu(II)meso-tetra(4-sulfonatopheny1) porphine in TiO2/SiO2 organic-inorganic gel using Z-scan technique
Authors: Zhuang Xiao-Bo  , Xia Hai-Ping  ,   Key Laboratory of Photo-electronic Materials, Ningbo University, Ningbo 315211, China
Published: December 2020

The Cu(II)meso-tetra(4-sulfonatopheny1) porphines (Cu(II)-TPPS) with various concentrations are incorporated into TiO2/SiO2 to form organic and inorganic composite gels via sol-gel process. With a Nd:YAG laser of 532 nm wavelength and 7 ns pulse width, the curves of Z-scan are measured under the condition of open aperture. Nonlinear absorption parameters of these materials, which are attributed to the reverse saturation absorptions of monomer and dimer of Cu(II)-TPPS, are obtained by fitting the above curves with Z-scan theroy. The result indicates that the nonlinear parameter of gel increases with doping concentration increasing. The nonlinear absorption coefficients of gels in 1.11×10-4 mol/L A2, 1.48×10-4 mol/L A3 and 3.01×10-4 mol/L A4 doping concentration are 1.705×10-11, 1.892×10-11, and 4.854×10-11 m/W, respectively. The effects of monomer and dimer on the nonlinear parameter are discussed. The reduction of the nonlinear parameter results from the increases of dimer and multimer as the doping concentration increases. The damage threshold of the gel is also measured and can reach up to ～5 J/cm2.
Confinement effect and interface effects on the thermoelectric properties of nano-ceramics: theoretical study
Authors: Zhang Rui-Zhi  , Chen Wen-Hao  , Yang Lu-Na  ,   Department of Physics, Northwest University, Xi'an 710069, China
Published: December 2020

The influences of electron and phonon confinement and interface effects on the thermoelectric performance of SrTiO3 nano-ceramic are studied by using the Boltzmann transport equations and density functional calculations. Theoretical calculations show that the figure of merit of nano-ceramic is greatly improved up to 0.8 at room temperature. The improvement is due mainly to the phonon confinement effect and the electronic energy filtering effect at the grain boundary. The electron confinement effect and the interface phonon scattering effect play a supporting role. These results may be conducive to the design of high-performance thermoelectric nano-ceramic.
The passivation of Al2O3 and its applications in the crystalline silicon solar cell
Authors: Zhang Xiang  , Liu Bang-Wu  , Xia Yang  , Li Chao-Bo  , Liu Jie  , Shen Ze-Nan  ,   Key Laboratory of Microelectronics Devices and Integrated Technology, Institute of Microelectronics, Chinese Academy of Sciences, Beijing 100029, China
Published: December 2020

The material characteristics and one of the preparation methods, atomic layer deposition of Al2O3 are introduced. The passivation mechanisms (chemical passivation and field-effect passivation) of Al2O3 films are demonstrated comprehensively, and optimization methods from the angles of film thickness, thermal stability and stack passivation are illuminated. The application of Al2O3 passivation in the crystalline silicon solar cell is provided, including passivated emitter rear locally diffused cell and passivated emitter and rear cell. Finally, the future study of the Al2O3 passivation process and the application to industry production are proposed.
The coercivity of the high temperature magnets Sm(CobalFe0.1Cu0.1Zr0.033)6.9 alloys
Authors: Wang Guang-Jian  , Jiang Cheng-Bao  ,   Key Laboratory of Aerospace Materials and Performance (Ministry of Education), School of Materials Science and Engineering, Beihang University, Beijing 100191, China;,   School of Science, Hebei University of Engineering, Handan 056038, China
Published: December 2020

The hysteresis behaviors domain structures and temperature coefficients of coercivity are investigated in Sm(CobalFe0.1 Cu0.1Zr0.033)6.9, which is aged at 810℃ and slowly cooled with a rate of 0.5℃/min, and then quenched at different temperatures. It is found that the demagnetization cures show two steps clearly as the alloys are quenched at 600℃, which means that there should have two pinnings on the domain wall, and its domain structure appears more as a zigzag shape domain, which means that there should be a small gradient of Cu distribution in the 1:5 cell boundary phase and a small domain wall pinning in the cell boundary phase. The maximum domain wall pinning should be at the interface between the 1:5 cell boundary phase and 2:17 cell phase. As the alloys are quenched at a lower temperature, the steps in the demagnetization cures disappear. At the same time, their domain structures become narrower, and show more attached domains, which means that a lower domain wall energy is in the 1:5 cell boundary phase and that the maximum domain wall pinning should be in the center of the 1:5 cell boundary phase. As the maximum domain wall pinning is at the interface between the 1:5 cell boundary phase and 2:17 cell phase, the coercivity will show an abnormal temperature dependence. While as the maximum domain wall pinning is in the center of the 1:5 cell boundary phase, the coercivity will decrease with temperature increasing. As the testing temperature rises to 500℃, the coercivities for all samples nearly come to the same values, and the maximum domain wall pinnings all should come to the interface between the 1:5 cell boundary phase and 2:17 cell phase.
High-oder symplectic FDTD scheme for solving time-dependent Schrdinger equation
Authors: Shen Jing  , Sha Wei E. I.  , Huang Zhi-Xiang  , Chen Ming-Sheng  , Wu Xian-Liang  ,   Key Laboratory of Intelligent Computing & Signal Processing, Anhui University, Hefei 230039, China;,   Department of Electronic Engineering, Hefei Normal College, Lianhua Road, Hefei 230601, China;,   Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, China
Published: December 2020

Using three-order symplectic integrators and fourth-order collocated spatial differences, a high-order symplectic finite-difference time-domain (SFDTD(3, 4)) scheme is proposed to solve the time-dependent Schrdinger equation. First, high-order symplectic framework for discretizing the Schrdinger equation is described. The numerical stability and dispersion analyses are provided for the FDTD(2, 2), FDTD(2, 4) and SFDTD(3, 4) schemes. The results are demonstrated in terms of theoretical analyses and numerical simulations. The spatial high-order collocated difference reduces the stability that can be improved by the high-order symplectic integrators. The SFDTD(3, 4) scheme and FDTD(2, 4) approach show better numerical dispersion than the traditional FDTD(2, 2) method. The simulation results of a two-dimensional quantum well and harmonic oscillator strongly confirm the advantages of the SFDTD(3, 4) scheme over the traditional FDTD(2, 2) method and other high-order approaches. The explicit SFDTD(3, 4) scheme, which is high-order-accurate and energy-conserving, is well suited for long-term simulation.
Method of identifying the relative position between standing wave of laser light and substrate in atom lithography
Authors: Wang Jian-Bo  , Qian Jin  , Yin Cong  , Shi Chun-Ying  , Lei Ming  ,   Division of Metrology in Length and Precision Engineering, National Institute of Metrology, Beijing 100013, China;,   China Defense Science and Technology Information Center, Beijing 100036, China
Published: December 2020

Standing wave of laser light acts as an array of lenses to focus the moving atoms in atom lithography. The position between standing wave and substrate plays an important role in determining the quality of depositional nanometer lines. Using the rule of Gaussian beam, a method of accurately identifying the position of standing wave of laser light is reported. By adjusting accurately the displacement stage which carries the beam focus lens and reflective mirror, the laser beam is subsequently shielded by depositional substrate. Signal of photoelectric detector is changed because of shielding the standing wave, so we can convert the displacement of standing wave into electrical signal. Positioning the standing wave against substrate is achieved by using the value of waist diameter of standing wave of laser light. Theoretical model is developed according to the experimental process. The result of numerical computation coincides well with the experimental record. This method realizes accurately positioning standing wave of laser light against substrate, and it provides the experimental basic for deeply studying the influence of the distance between standing wave and substrate on the quality of depositional nanometer lines.
The magnetic and quantum transport properties of sandwich-structured Tan(B3N3H6)n+1 clusters
Authors: Zhang Cai-Xia  , Guo Hong  , Yang Zhi  , Luo You-Hua  ,   College of Physics and Optoelectronics, Taiyuan University of Technology, Taiyuan 030024, China;,   School of Physics and Electronics, Henan University, Kaifeng 475004, China
Published: December 2020

Using density functional theory and non-equilibrium Green's function technique, we investigate the magnetic and quantum transport properties of Tan(B3N3H6)n+1 (n ≤ 4) clusters. The results show that these clusters have sandwich structures as the ground states and their stabilities are all very high, and that the total magnetic moment increases linearly with cluster size increasing. When these sandwich clusters are coupled to Au electrodes, the Au-Tan(B3N3H6)n+1-Au system could exhibit high spin-filter capability under finite bias voltage and can be viewed as a new kind of low-dimensional spin filter.
Junctionless low-voltage thin-film transistors based on indium-tin-oxide
Authors: Zhao Kong-Sheng  , Xuan Rui-Jie  , Han Xiao  , Zhang Geng-Ming  ,   Key Laboratory for Micro-Nano Optoelectronic Devices of Ministry of Education, Hunan University, Changsha 410082, China
Published: December 2020

Bottom-gate junctionless thin-film transistors (TFTs) based on indium-tin-oxide (ITO) are fabricated at room temperature. Source/drain electrodes and channel layer are the same ITO thin films without source/drain junction formation, hence the fabrication process is greatly simplified and the fabrication cost is reduced. We employ electric-double-layer (EDL) SiO2 with large capacitance as the gate dielectric, and find that the drain current can be effectively modulated by the gate bias when the thickness of ITO film decreases to about 20 nm. These junctionless TFTs show excellent electrical performances with a small subthreshold swing of 0.13 V/dec, a high mobility of 21.56 cm2/V·s and a large on/off ratio of 1.3× 106. The performances of these junctionless TFTs do not show significant degradation even after 4 months in air ambient, the subthreshold swing is still 0.13 V/dec, the mobility slightly decreases to 18.99 cm2/V·s and the on/off ratio is still larger than 106. Such TFTs are very promising for the applications in low-cost low-power portable electronic products and novel sensors.
Processing of GPS/LEO radio occultation recorded in open-loop mode
Authors: Xu Xian-Sheng  , Guo Peng  , Xu Tao-Ling  , Hong Zhen-Jie  ,   Ningbo Institute of Technology, Zhejiang University, Ningbo 31500, China;,   Shanghai Astronomical Observatory, Chinese Academy of Sciences, Shanghai 200030, China;,   Institute of Earthquake Science, China Earthquake Administration, Beijing 100036, China;,   School of Mathematics & Information Science, Wenzhou University, Wenzhou 325027, China
Published: December 2020

In the moist lower troposphere, traditional phase-locked loop tracking of GPS (Global Position System) signal will introduce errors in the retrieved results. Both internal and external method can be used to remove navigation data modulation (NDM) and accurately recover the phase of GPS signals recorded in open-loop mode. The internal method removes the NDM using relationship between adjacent samples, while the external method removes the NDM using the externally recorded NDM bit data. Both above-mentioned methods are used to process the constellation observing system for meteorology, ionosphere and climate (COSMIC) radio occultation data. COSMIC case study shows that internal method may include half-cycle slip in the recovered phase, which will lead to error in the retrieved refractivity. About 3130 COSMIC radio occultation soundings recorded in open-loop mode are processed by the internal and external method, and statistical comparison results of retrieved refractivity with that from the European Centre for medium-range weather forecasts (ECMWF) analyses show that the external method has a better penetration ability than the internal method in the lower moist troposphere. The mean of fractional difference in refractivity retrieved by external method is smaller than that by internal method below about 3 km.
The distribution functions of characteristic quantities for random noise signal of photodetector
Authors: Yan Zhen-Gang  , Lin Ying-Lu  , Yang Juan  , Li Zhen-Hua  , Bian Bao-Min  ,   Department of Information Physics and Engineer, Nanjing University of Science and Technology, Nanjing 210094, China
Published: December 2020

Based on the random process of the photodetector noise signals {Vi}, the different characteristics of the two parts of the random measurementstability constant part and random fluctuation part are analyzed. A new mathematical model of the random noise signal is established. The theoretical analysis shows that the statistical distributions must obey the relationship of nonlinear transform. The distribution laws of the different characteristic quantities in the same random process are studied experimentally, such as, the amplitude of extreme, the amplitudes of the rising edge and falling edge, the interval between extreme points, the difference between adjacent amplitudes, the product value of the quantities and the quotient value of the quantities. And the statistical distribution of these characteristic quantities matches well with the form of the lognormal distribution. From the theoretical and experimental results we can conclude that the lognormal distribution plays an important role in describing the random fluctuation part characteristic of random process.
Polarization dependence of carrier-induced refractive index change
Authors: Miao Qing-Yuan  , Cui Jun  , Hu Lei-Lei  , He Jian  , He Ping-An  , Huang De-Xiu  ,   School of Electronic Information, Wuhan University, Wuhan 430072, China;,   Accelink Technologies Co., Ltd, Wuhan 430205, China;,   College of Optoelectronic Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
Published: December 2020

The influences of carrier density, tensile strain, well width and barrier material component on the refractive index changes of TE mode and TM mode in quantum well are analyzed. Then the quantum wells having characteristics of both large refractive index change (on the order of 10-2) and low polarization dependence (on the order of 10-4) in a wavelength range from 1530 nm to 1570 nm are designed by comprehensively integrating the parameters above. The result shows that almost the same spectra of refractive index change can be acquired by integrating different groups of parameters.
Beta effect and slowly changing topography Rossby waves in a shear flow
Authors: Song Jian  , Liu Quan-Sheng  , Yang Lian-Gui  ,   College of Mathematical Science, Inner Mongolia University, Hohhot 010021, China;,   College of Sciences, Inner Mongolia University of Technology, Hohhot 010051, China
Published: December 2020

In barotropic fluids, based on the quasi-geostrophic potential vorticity equation, an inhomogeneous mKdV-Burgers equation including slowly changing topography and an external source is derived by employing the perturbation method and stretching transforms of time and space. With the inspection of the evolution of the amplitude of Rossby waves, it is found that beta effect, topography effect, slowly changing topography and an external source are all the important factors, and that the solitary Rossby wave is induced thought the basic stream function has a shear flow . On the assumption that the nonlinear and topographic effects are in balance, an inhomogeneous mKdV-Burgers equation is derived, the results show that the topography and Rossby wave interact in the barotropic flows. The inhomogeneous mKdV-Burgers equation describing the evolution of the amplitude of solitary Rossby wave as the change of Rossby parameter β(y) with latitude y, topographic forcing, slowly changing topography and the external source is obtained.
The influence of dielectric truss on transmission characteristics of frequency selective surface
Authors: Chen Xin  , Gao Jin-Song  , Xu Nian-Xi  , Wang Yan-Song  , Feng Xiao-Guo  ,   Key Laboratory of Optical System Advanced Manufacturing Technology, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China;,   Graduate School of the Chinese Academy of Sciences, Beijing 100039, China
Published: December 2020

In order to analyze the influence of dielectric truss structure on frequency selective surfaces (FSS) transmission characteristics, as an example, the FSS of Y ring unit and the truss made of polyimide are investigated by the finite difference time domain method. The relevant physical model is developed and pore blocking rate is defined. Through the analysis it is proved that the variations of truss period and rib width will affect the FSS, so they become the main parameters to measure dielectric truss structure, and that the improvement of the aperture stop ratio will increase transmission loss. When truss period changes from infinity to 80 mm the transmittance of passband is reduced by more than 0.9 dB on an average; when the ribs width increases from 0 to 10 mm, the transmittance of passband is reduced by more than 0.6 dB on an average. When aperture stop ratio is lower than 12.11%, the passband produces no shipt. When aperture stop ratio is less than 4.12%, the influence of the truss on FSS is negligible. The FSS specimens is fabricated by coating and lithography process, the dielectric truss is machined by numerically controlled machine, and the microwave measurement is carried out in a dark room. The experimental results and the calculation results are verified to be in good agreement with each other. Therefore the present study presents an experimental and theoretical reference for designing the FSS stealth radar with the dielectric truss structure.
Adaptive optics multispectral photoacoustic imaging
Authors: Jian Xiao-Hua  , Cui Yao-Yao  , Xiang Yong-Jia  , Han Zhi-Le  ,   Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou 215163, China
Published: December 2020

Photoacoustic imaging is an advanced medical imaging technology based on the effect of ultrasound generation by electromagnetic irradiation. However in photoacoustic imaging, because the optical property of tissue is always very complex, the aberration of light in tissue is ineluctable and the image spot is dispersed, which greatly influences the photoacoustic image resolution. For improving the lateral resolution of photoacoustic imaging, the adaptive optics multispectral photoacoustic imaging system is proposed in this paper. In this system an adaptive optics sub-system is designed to correct the wavefront errors of the illuminating light for obtaining high-resolution images of biological tissues. Moreover, the multispectral imaging is combined to obtain different wavelength photoacoustic images, which is useful for distinguishing organization accurate structure, identifying organizational components, etc. The simulation results demonstrate that when the wavefront errors are corrected by the adaptive optics system, the image resolution and quality are improved significantly. This research will be helpful for improving the ability and application of photoacoustic imaging.
Two-dimensional numerical analysis of the collection mechanism of single event transient current in NMOSFET
Authors: Zhuo Qing-Qing  , Liu Hong-Xia  , Hao Yue  ,   Key Laboratory for Wide Band Gap Semiconductor Materials and Devices of Education, School of Microelectronics, Xidian University, Xi'an 710071, China
Published: December 2020

The single event effects in NMOSFET at different values of drain bias, gate length and striking location are thoroughly analyzed by two-dimensional numerical simulator in this paper. The results show that single event transient current increases with the increase of drain bias and with the decrease of gate length. Furthermore, single event transient current varies with the electric field at some places in the device. The present study provides important guidance on the devices design of mitigating the single event effects.
Analytical model of range-doppler of cone-cylinder combination
Authors: Yu Wen-Ying  , An Li-Qian  ,   School of Mechanics and Civil Engineering, China University of Mining and Technology Beijing, Beijing 100083, China;,   School of Opto-Electronic Information Science and Technology, Yantai University, Yantai 264005, China
Published: December 2020

The technique of laser range-Doppler image has been intimately noticed by aerospace and national defense circles. A analytical model of laser range-Doppler image of cone-cylinder combination is proposed in this paper. The analytical model includes the contribution of disk base. The analytical model can provide the effects of geometry parameters, the roughness of the surface, attitude, and pulse duration on laser range-Doppler image. This analytical model can reduce into the analytical model of range-Doppler image of cone and cylinder. This analytical model can reduce into the analytical model of Doppler spectra for plane waves. The influences of geometry parameters, and attitude are analyzed numerically by using the analytical model. The results indicate that the laser range-Doppler image of cone-cylinder combination can show the information about geometrical shape and attitude of target. Combining the theory and measurements, the analytical model can be used for indentifying physical parameters and geometrical parameters of cylinders, cones and cone-cylinder combination. This analytical solution is of significance for the laser Doppler velocimetry and ladar applications.
Hybrid solutions of three functions to the (2+1)-dimensional sine-Gordon equation
Authors: Gao Mei-Ru  , Chen Huai-Tang  ,   School of Science, Linyi University, Linyi 276005, China;,   Xinzhou Branch, Agricultural Bank of China, Xinzhou 034000, China;,   School of Mathematical Science, Shandong Normal University, Jinan 250014, China
Published: December 2020

Based on a constructed Wronskian form expansion method, a few new types of hybrid solutions to the (2+1)-dimensional sine-Gordon equation are obtained. These solutions are some various combinations of trigonometric functions, hyperbolic functions and Jacobi elliptic functions.
Study on phase analysis of nanoparticles by high-voltage electrical explosion method of copper wire
Authors: Li Shi-Wen  , Feng Guo-Ying  , Li Wei  , Han Jing-Hua  , Zhou Sheng-Yang  , Yin Jia-Jia  , Yang Chao  , Zhou Shou-Huan  ,   School of Engineering and Technology, Panzhihua University, Panzhihua 617000, China;,   College of Electronics & Information Engineering, Sichuan University, Chengdu 610065, China
Published: December 2020

Copper nanoparticles are produced by high-voltage electrical explosion of copper wires. The high-voltage breakdown experimental setup for copper is built. The morphology and composition of the breakdown material are tested by the transmission electron microscopy (TEM) and scanning electron microscopy (SEM), and X-ray diffractometry (XRD) and energy dispersive spectroscopy(EDS) methods, respectively. Based on the morphology, size distribution, elemental spectrum (EDS), and XRD analysis of the breakdown material, the phase characteristics of high-voltage breakdown copper wire are studied. The results show that wire is fully ionized under high pressure, forming a filamentous distribution which is composed of condensation of nanoparticles. The diameters of copper nanoparticles are between 30 nm and 60 nm. The nanoparticles product is composed of Cu and O elements. The product is a mixture of metallic copper, cupric oxide and cuprous oxide. The particle size and its product composition are controlled by varying length and diameter of the copper wire, discharge voltage, etc.
Theoretical study of luminance of GaN quantum dots planted in quantum well
Authors: Wang Du-Yang  , Sun Hui-Qing  , Xie Xiao-Yu  , Zhang Pan-Jun  ,   Laboratory of Nanophotonic Functional Materials and Devices, Institute of Opto-Electronic Materials and Technology, South China Normal University, Guangzhou 510631, China
Published: December 2020

A theoretical simulation of electrical and optical characteristics of quantum dot (QD) light-emitting diodes depending on the QD sizes is conducted with APSYS software. The electron and hole concentration in the LED and the radioactive recombination rate are studied. Simulation results show that with the increase of the QD size, the emission wavelength has a red shift. With the radius of QD increasing from 1.8 nm to 13 nm , the red shift of emission wavelength has reaches 309.6 meV. The use of the QDs with different sizes planted in quantum well can achieve full-color display with a single LED. When different quantum wells are planted with different QDs, the LED turns into a muti-wavelength luminescence even white LED. We can improve the intensity of each wavelength by adjusting the surface density of QDs. The luminous uniforming of the muti-wavelength LED can be effective improved by adjusting the QD surface density.
Preparation of ZrO2:Eu3+-Bi3+ phosphor and Bi3+ sensitizing characteristic emission of Eu3+ ions
Authors: Sang Shi-Jing  , Lü Shu-Chen  , Qu Xiu-Rong  , Yang Xiao-Xu  , Zhang Li-Li  ,   Key Laboratory of Photoelectric Bandgap Materials, Ministry of Education, Harbin Normal University, Harbin 150025 , China
Published: December 2020

Eu3+ and Bi3+ codoped ZrO2 nanocrystalline powders are prepared by chemical co-precipitation method. The room temperature characteristic emission of Eu3+ can be observed from each sample. We determine the crystal structures and luminescent properties of the samples. It is shown that the crystal phase of nanocrystalline ZrO2:Eu3+-Bi3+ powder calcined at 600 ℃ is tetragonal, and it turns into the mixture of tetragonal and monoclinic phase as temperature rises to 800, 950, and 1100 ℃. It is obvious that characteristic emission intensity of Eu3+ in the tetragonal phase is greater than in the mixed phase. Bi3+ can sensitize the room temperature characteristic emission of Eu3+ in nanocrystalline ZrO2.
Black hole mass and radiation pressure of Seyfert 1 galaxies
Authors: Xiong Ding-Rong  , Zhang Xiong  , Zheng Yong-Gang  , Huang Bang-Rong  , Mao Li-Sheng  , Liu Wen-Guang  , Cha Yong-Juan  ,   College of Physics and Electronics, Yunnan Normal University, Kunming 650092, China
Published: December 2020

We collect 214 Seyfert 1 galaxies(147 narrow line Seyfert 1 and 67 broad line Seyfert 1) and research black hole mass bulge velocity dispersion Eddington radio luminosity at 5100 Å and redshift. Our conclusions are follows: (1) when computing black hole mass, we should consider the effect of radiation pressure, especially for the narrow line Seyfert 1 galaxies; (2) when the effect of radiation pressure is considered, narrow line Seyfert 1 galaxies meet MBH-σ relation of normal galaxies and are in su-Eddington accretion; (3) in a large samples, the evolution of Seyfert 1 galaxies is from narrow line Seyfert 1 galaxies to broad line Seyfert 1 galaxies, which is consistent with other results obtained in different ways.
The chaotic hash function based on spatial expansion construction with controllable parameters
Authors: Liao Dong  , Wang Xiao-Min  , Zhang Jia-Shu  , Zhang Wen-Fang  ,   Key Laboratory of Signal and Information Processing of Sichuan Province, Southwest Jiaotong University, Chengdu 610031, China;,   Institute of Information Science and Technology, Southwest Jiaotong University, Chengdu 610031, China
Published: December 2020

A novel chaotic one-way hash function based on spatial expansion construction with controllable parameter is presented which combines with the advantages of both chaotic system and parallel hash function. In the proposed approach, the hash model of message block is determined by chaotic dynamic parameter. The new method improves the security of hash function and avoids degrading the system performance at the same time. Theoretical and experimental results show that the proposed method has high performance in parallel algorithm, nearly uniform distribution and desired diffusion and confusion properties.
Dynamic model of generalized thermoelasticity based on thermal mass theory
Authors: Wang Ying-Ze  , Song Xin-Nan  ,   Department of Energy and Power Engineering, Jiangsu University, Zhenjiang 212013, China
Published: December 2020

A lagging response in time exists between the propagation of heat flux and the establishment of temperature gradient and it is affected by the space effect during the heat conduction with the micro-scale property. Based on the general heat conduction law of thermal mass, the dynamic model of generalized thermoelasticity is established by Clausius inequality and Helmholtz free energy, where the inertia effect on the time and space of heat flux and temperature is involved. The guiding equations are derived and given for the isotropic and homogeneous materials. By comparison with the existing models of generalized thermoelasticity, the guiding equations can reduce to the L-S, G-L and G-N models when the heat flux is not very high, so that the inertia effect on space of heat flux and temperature can be ignored. For micro-scale heat conduction, the heat flux may be very high and the inertial force due to the spatial velocity variation cannot be ignored, the non-Fourier phenomenon will take place even under steady state condition. In such cases, the thermal conductivity is affected by the inertia effect of the space, which can be explained by the model established in the paper. Meanwhile, the physically impossible phenomenon that thermal conductivity changes with structure size induced by existing generalized model can also be eliminated.
A quantitative model and experimental investigations of wall shear stress between solid and gaseous fluid using liquid crystal coating
Authors: Zhang Song-Peng  , Zhang Xiang-Jun  , Tian Yu  , Meng Yong-Gang  ,   State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China
Published: December 2020

Measurement of wall shear stress (WSS) has important significance in many fields, such as spacecraft surface flow visualization and drag reduction of solid-liquid interface. Various measuring methods have been developed with the rapid development of micro and nano technology. This paper focuses on the measurement of WSS by using nematic liquid crystal coating. A quantitative model is built to describe the relationship between the variations of director orientation and the WSS based on the curvature elasticity theory of liquid crystal. Then an experiment setup is built to verify this model using 5 CB and 7 CB through the optical method. There is good consistence between the theoretical model and experiment results. Finally, the WSS measuring limits and influencing factors are discussed such as the thickness of the liquid crystal layer, the elastic coefficient of the molecule and measurement resolution.
Study of neutral Bs mixing in a family non-universal Z' model
Authors: Lu Gong-Ru  , Li Xin-Qiang  , Li Yan-Min  , Su Fang  ,   Department of Physics, Henan Normal University, Xinxiang 453007, China;,   Institute of Particle Physics, Huazhong Normal University, Wuhan 430079, China
Published: December 2020

Motivated by recent measurements of the neutral Bs-meson mixing, obtained by LHCb group and the Tevatron, and the possibility to have sizable NP effects in 12s, we revisit the Bs mixing in a family non-universal Z' model. We assume that the Z' boson contributes to the off-diagonal element M12s and also to the off-diagonal element 12s via tree-level Z'-induced b scc operators. We find that, with the constraints from Mss and the indirect CP asymmetry in BdJ/KS imposed, the present measured 1 experimental ranges for afss could not be reproduced. Thus, such a specific model could not simultaneously explain the present data on Bs mixing. It is expected that with the operation of the LHCb group and the future super B experiments, more accurate measurements, especially of the flavour-specific CP asymmetries, could shed light on the issue.