bluuebunny/crossref_metadata_2025 huggingface dataset:
Quasi-geostrophic theory and its application based on baroclinic two-layer model
Authors: Wang Xiu-Ming  , Zhou Xiao-Gang  , Tao Zu-Yu  , Yu Xiao-Ding  ,   China Meteorological Administration Training Center, Beijing 100081, China;,   Physical School of Peking University, Beijing 100871, China
Published: December 2020

The quasi-geostrophic theory is the theoretical basis of the short-term weather forecast. Quasi-geostrophic motion equations of mid-latitude synoptic -scale movement are the core of quasi-geostrophic theory. Based on baroclinic two-layer model, quasi-geostrophic potential tendency equation and vertical motion equation can more clearly explain the movement and development of upper and surface weather systems. The movement of 500 hPa upper trough depends on the vorticity advection of 500 hPa, its development is determined by 500 hPa vorticity advection and differential vorticity advection between 250 and 750 hPa . The movement and development of cyclone depend on the positive temperature advection at 500 hPa and differential vorticity advection between 250 and 750 hPa. A case of snoptic system evolution demonstrates that quasi-geostrophic theory based on baroclinic two-layer model is conducive to the quick recognition of the characteristics of mid-latitude synoptic scale baroclinic development system, the understanding of the objective law of the development of the weather systems and the physical basis of numerical products.
The signal-to-noise ratio of the quarter beam of wind imaging polarization interferometer
Authors: Zhang Xuan-Ni  , Zhang Chun-Min  , Ai Jing-Jing  ,   Non-equilibrium Condensed Matter and Quantum Engineering Laboratory, the Key Laboratory of Ministry of Education School of Science, Xi'an Jiaotong University, Xian 710049, China;,   Institute of Physics and Electronic Engineering, Xianyang Normal University, Xianyang 712000, China
Published: December 2020

The novel static polarization wind imaging interferometer adopts four-face pyramid prism and polarization array to obtain four different phase interferograms on four sections of CCD once. It can detect the target in real time and overcome the moving mirror scan detection mode defect that leads to be unable to accurately detect the rapily changing target. For the signal beam that is split into four equal parts, their intensities drop significantly, so whether the signal can be detected is a key problem. In this paper, the target spectral characteristic of the airglow is taken as the starting point of analysis, then the optical transmission properties and response of the NSPWII system and CCD signal-to-noise ratio are analyzed. Finally the conclusion is obtained that weak signal (such as night airglow) cannot be detected in the conventional detecting mode. Some improving measure is presented which extends light integration time, adopts pixel merger technology and select high sensitivity CCD (as electron multiplication CCD), they all can improve the signal-to-noise ratio effectively. After integrated using the these measures, the signal-to-noise ratio and responsiveness of NSPWII system are calculated. In view of the rapid changes of cost and objectives, only pixel binning is adopted, and the simulated curve of signal-to-noise ratio versus digital output is obtained. The result shows that the weak signal as night airglow can be detected.
The inverse method of carbon monoxide from satellite measurement and the result analysis
Authors: Liu Cheng  , Bai Wen-Guang  , Zhang Peng  , Sun You-Wen  , Si Fu-Qi  ,   Satellites, National Satellite Meteorological Center, China Meteorological Administration, Beijing 100081, China;,   Key Laboratory of Environmental Optics and Technology, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China
Published: December 2020

Greenhouse effect is one of the main reasons for climate change. Carbon monoxide (CO) is a critical air pollutant because of its short-term harmful health effects. Furthermore, since CO emission has a global warming potential, it exacerbats the climate change as an indirect greenhouse gas. Due to the fact that the number of ground-based stations is less and the chemical model simulation is greatly dependent on assumption, satellite observation becomes the effective way to acquire the information about CO distribution. Sciamachy is the first satellite instrument to allow retrieval of CO by measuring absorption in the near infrared region from reflected and scattered sunlight, which is highly sensitive to the lower layers of the troposphere where the sources, such as biomass burning, are located, and where the bulk of the gases is usually found. In this study the Sciamachy CO vertical column density is successfully inversed; after applying the instrument and cloud correction, yearly and seasonal results are presented. Finally by comparing them with the fire counts of ATSR dataset and the distributions of population density and coal mines, the CO emission sources are preliminary deduced.
Implementation and analysis of the perfectly matched layer with auxiliary differential equation for the multiresolution time-domain method
Authors: Liu Ya-Wen  , Chen Yi-Wang  , Xu Xin  , Liu Zong-Xin  ,   National Key Laboratory on Electromagnetic Environment and Electro-optical Engineering, PLA University of Science and Technology, Nanjing 210007, China
Published: December 2020

A new implementation of perfectly matched layer (PML) with auxiliary differential equation (ADE-PML) is presented for the multiresolution time-domain method. The implementation is easier to obtain and can save more memories than the popularly used PML proposed by Berenger and the anisotropic perfectly matched layer (APML) when a more generalized medium is treated. Numerical results demonstrate that the ADE-PML is more superior to the PML and APML in absorbing propagation modes and low-frequency evanescent modes.
Molecular dynamics simulation of isothermal crystallization dynamics in Cu nanocluster
Authors: Chen Qing  , Sun Min-Hua  ,   Key Laboratory of Photoelectric Bandgap Materials, Ministry of Education, School of Physics and Electronic Engineering, Harbin Normal University, Harbin 150025, China
Published: December 2020

We investigate the isothermal crystallizations of nanoparticles composed, respectively, of 4000 Cu atoms (Cu4000) and 13500 Cu atoms (Cu13500), and bulk Cu according to on embedded atom model, using molecular dynamics simulations. We note that different sizes of Cu nanoparticles display multistep crystallization at low temperature, and their crystallization time distribution is wider than at high temperature, shown by analyzing the structural and dynamic properties of isothermal crystallization. Moreover, the size of particle plays an important role in the crystallization process. The larger the size, the longer the crystallization time is. However, we find that there is a critical size rc. The crystallization time increases with particle size increasing when the size is less than rc. On the contrary, when the size is more than rc, the crystallization time decreases with particle size increasing.
Mechanism of three kink effects in irradiated partially-depleted SOINMOSFET's
Authors: Zhuo Qing-Qing  , Liu Hong-Xia  , Peng Li  , Yang Zhao-Nian  , Cai Hui-Min  ,   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 variations in ID-VD characteristic of 0.8 μm SOINMOS transistors are studied, which are exposed to 60Co γ ray at a dose rate of 50 rad (Si)/s. The results show that the linear kink effects of these samples at each dose level ane not presente due to the optimizations of manufacture process and layout design. The drain voltage that corresponds to the impact ionization induced kink effect, increases, with dose level. An anomalous "Kink" effect in the back gate ID-VSUB characteristics of the partially depleted SOINMOS transistors is observed at a high dose level, which is attributed to interface trap states generated at the buried oxide/silicon film interface during irradiation.
First-principles study on the energy bandgap bowing parameter of wurtzite BexZn1-xO
Authors: Zheng Shu-Wen  , Fan Guang-Han  , Zhang Tao  , Su Chen  , Song Jing-Jing  , Ding Bin-Bin  ,   Institute of Opto-electronic Materials and Technology, South China Normal University, Guangzhou 510631, China
Published: December 2020

First-principles plan-wave pseudopotential method is used to calculate the energy bandgap properties, bowing parameters and structural properties of wurtzite BexZn1-xO alloys. The results show that the energy bandgaps and bowing parameters of BexZn1-xO alloys increase with Be content increasing. We find the energy bandgaps corrected of BexZn1-xO alloys to be in accordance with the experimental value. The reason about the energy bandgap broadening is also analyzed. The average bowing parameter of BexZn1-xO alloys is 6.02 eV, which is in good agreement with previous experimental result. The bowing parameter mostly arises from volume deformation of alloy and charge transfer effect. Futhermore, we analyze the changes of lattice parameter, average bond length and average second-neighboring distance with Be content in BexZn1-xO alloys.
Wind partitioning and reconstruction with variational method in a limited domain I: theoretical frame and simulation experiments
Authors: Zhao Yan-Lai  , Huang Si-Xun  , Du Hua-Dong  ,   Institute of Meteorology, PLA University of Science and Technology, Nanjing 211101, China
Published: December 2020

As is well known, the efficient method to wind partitioning and reconstruction is to introduce the velocity potential and stream function which are calculated from divergence and vorticity by solving two Poisson's equations. Since velocity potential and stream function are coupled at the boundary of limited domain, the wind partitioning problem is nonunique. To vercome the nonuniqueness of the wind portioning, a new variational adjoint method combined with regularization is proposed in this paper, which is based on the control of velocity potential and stream function boundary values under Dirichlet conditions. The cost function is composed of two parts, one is the observation term to minimize the error of the reconstructed wind field, and the other is the regularization term to guarantee the uniqueness of the reconstruction problem by seeking a stable regularization solution within meteorological content. The results of numerical experiments demonstrate that after choosing an appropriate regularization parameter, the new variational adjoint method combined with regularization is efficient and suitable for wind portioning and reconstruction in a limited domain.
Asymptotic solution of thermal-solutal capillary convection in a slowly rotating shallow annular pool of two components solution
Authors: Gong Zhen-Xing  , Li You-Rong  , Peng Lan  , Wu Shuang-Ying  , Shi Wan-Yuan  ,   Key Laboratory of Low-grade Energy Utilization Technologies andSystems of Ministry of Education, College of Power Engineering, ChongqingUniversity, Chongqing 400044, China
Published: December 2020

In order to understand the characteristics of the coupled thermal and solutal capillary convection with the radial temperature gradient in a slowly rotating shallow annular pool with the free surface, the asymptotic solution is obtained in the core region using asymptotical analysis in the limit as the aspect ratio, which is defined as the ratio of the layer thickness to the gap width, goes to zero. The influences of the rotating, Soret effect, solute diffusion coefficient, buoyant force and geometric parameters on fluid flow are analyzed. The results show that when the rotating and the solutal capillary force and the buoyancy induced by the ununiform distribution of solute concentration are not considered, the asymptotic solution is the same as that of the previous work. The influences of the rotating, the buoyancy, solute diffusion coefficient and the geometric parameters on the fluid flow are all small and the coupled thermal and solutal capillary forces play a dominant role in the convection. When the coupled forces are in the same direction, the flow is reinforced, otherwise, the flow is suppressed.
Photodetachment of H- near a deform sphere
Authors: Li Shao-Sheng  , Wang De-Hua  ,   School of Physics and Optoelectronic Engineering, Ludong University, Yantai 264025, China
Published: December 2020

On the basis of the theoretical imaging method, we study the photodetachment of H- near a deform sphere. We deduce the formula of the detached electron flux. Then we calculate the detached electron flux distribution and the photodetachment cross-section. The calculation results suggest that the influence of the plane on the photodetachment of negative hydrogen ion is only within a certain range. In the region close to the z axis, the spherical effect dominates and the electron flux and photodetachment cross section are the same as those that exist only on the sphere surface. While in the region far from the z axis, both the plane and sphere surface have significant effect and the electron flux and photodetachment cross section become much complicated. If we fix the radius of sphere and the distance between the deform sphere and the negative hydrogen ion, the oscillating amplitude in the electron flux fist increases and then decreases with the increase of the photon energy. Finally it increases slowly. But the oscillating frequency becomes complicated at all times. If we fix the distance between the deform sphere and the negative hydrogen ion, the detached electron flux distribution becomes more like that in the sphere case as the radius of the sphere increases. Hence, we can control the photodetachment of H- near the deform sphere by changing the incident photon energy or the radius of the sphere. Our results will provide some reference values for the photodetachment of H- near the curved surface and the experimental research of microscopy photodetachment.
The aperture averaging effect of scintillation of pseudo-partially Gaussian-Schell model beam propagation in turbulent atmosphere
Authors: Qian Xian-Mei  , Zhu Wen-Yue  , Rao Rui-Zhong  ,   Key Laboratory of AtmosphericCompositions and Optical Radiation of Chinese Academy of Sciences, Hefei Institutes of Physics of Chinese Academy of Sciences, AnhuiInstitutes of Optics and Fine Mechanics, Hefei 230031, China
Published: December 2020

By using numerical simulation, the propagation of pseudo-partially coherent Gaussian-Schell model beam in atmospheric turbulence is simulated. The properties of intensity fluctuation of different receiving aperture and aperture averaging factors are statistically analyzed. And the influence of relative changing frequency of the modulating phase which models the partial coherence of beam source on scintillation index is also discussed. The simulation results of pseudo-partially coherent beam are compared with those of the well-developed partially coherent beam and fully coherent Gaussian beam. It is found that the reduction of coherence degree may cause scintillation index to decrease. However, the aperture averaging effect is weakened at the same time. At the same receiving aperture diameter, the aperture averaging factor of pseudo-partially coherent beam is greater than that of the fully coherent beam. The increase of relative changing frequency of modulating phase may cause a reduction of scintillation index to some degree. And with the increase of relative changing frequency, the scintillation index of pseudo-partially coherent beam tends to be coincident with that of the partially coherent beam.
Static Fourier-transform hyperspectral imaging full polarimetry
Authors: Li Jie  , Zhu Jing-Ping  , Qi Chun  , Zheng Chuan-Lin  , Gao Bo  , Zhang Yun-Yao  , Hou Xun  ,   Shaanxi Key Laboratory of Information Photonic Technique, KeyLaboratory for Physical Electronics and Devices of the Ministry of Education, School of Electronic and Information Engineering, Xi’an Jiaotong University, Xi’an 710049, China;,   Department of Information and Communication Engineering, School of Electronic and Information Engineering, Xi’an Jiaotong University, Xi’an710049, China
Published: December 2020

Spectral imaging and polarimetric imaging are both advanced optical detection techniques. Owing to their wide potential in military and civil communities, these techniques have rapidly developed within the past two decades and become well-recognized tools in remote sensing. In recent years, these two techniques presented a new trend toward merging into the imaging spectropolarimetry, and make the optical remote sensing tend to multi-dimensional and multi-information fusion. However, in conventional imaging spectropolarimeters, rotating polarization elements, electrically controllable components, and microretarder or micropolarizer arrays are typically required. These apparatuses generally suffer from vibration, electrical noise, heat generation, and alignment difficulty. Consequently, the incorporation of mechanical components typically increases the complexity and reduces the reliability of the measurement system. To overcome these drawbacks, we propose a novel method of real-time measuring the spectrum, polarization and imaging of scenes with static birefringent crystal elements in 2010. In this paper, the concept and theory of a sensor based on the method are given. With specially aligned static birefringent retarders, different phase factors are modulated into the Stokes vector of incidence light. After passing through a static birefringent interferometer, the spectrally dependent Stokes parameters are distributed into several separated interferogram channels. With corresponding Fourier-transform demodulation, the wavelength-dependent polarization, spectral and 1-D spatial imaging of objects can be completely obtained with a single snapshot. The simulated and experimental demonstration of the sensor are also presented. This research gives a new way for spectropolarimetric imaging measurement, and provides theoretical and practical support for the development of new space remote sensors.
Interaction between two edge dislocations in the presence of a tilted lens
Authors: Chen Hai-Tao  , Gao Zeng-Hui  , Xiao Shang-Hui  , Wang Fan-Hou  , Cheng Xiao-Hong  ,   Computational Physics Key Laboratory of Sichuan Province, School of Physics and Electrical Engineering, Yibin University, Yibin 644000, China
Published: December 2020

The interaction between two edge dislocations in the presence of a tilted lens is studied. It is shown that for the interaction between two off-axis edge dislocations, the edge dislocations vanish, and one or two noncanonical vortices appear under certain conditions. A noncanonical vortex appears for the interaction between the on-axis edge dislocation and off-axis edge dislocation. However, one or two edge dislocations may take place when two edge dislocations are perpendicular or parallel to each other in the initial plane. The variation of the tilt coefficient does not affect the type and number of phase singularities, but the relation between the transverse position of phase singularities and the tilt coefficient is linear. The three-dimensional trajectories of vortices are nonlinear while the center of the pair of vortices propagates along a line during propagation.
Lasing in dye-doped photonic crystals at the edge of fluorescence band gaps
Authors: Zhao Qiu-Ling  , Lü Hao  , Zhang Qing-yue  , Niu Dong-jie  , Wang Xia  ,   Institute of Optical Information Technology, School of Mathematics and Physics, Qingdao University of Science and Technology, Qingdao 266061, China
Published: December 2020

Based on holographic lithography, layered dye-doped photonic crystals are fabricated in dichromated gelatin emulsions. Under pumping of 532 nm pulse laser, fluorescence spectrums of samples show up remarkable band gaps, and lasing is achieved at the edge of fluorescence band gap with pumping energy increasing. Furthermore, the effects on lasing of matching between the edge of band gap and the peak of fluorescence are studied. Lasing threshold becomes lower as the edge of band gap is closer to the peak of fluorescence. Otherwise, it is difficult for lasing. The study provides new idea and method for the development of super low-threshold photonic crystal laser.
The analytical approximate solutions of capillary flow in circular tubes under microgravity
Authors: Li Yong-Qiang  , Zhang Chen-Hui  , Liu Ling  , Duan Li  , Kang Qi  ,   Institute of Applied Mechanics, College of Science, NortheasternUniversity, Shenyang 110819, China;,   National Microgravity Laboratory, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China
Published: December 2020

The capillary flow in a circular tube under microgravity environment is investigated by the homotopy analysis method (HAM), and the approximate analytical solution in the form of series solution is obtained. Different from other analytical approximate methods, the HAM is totally independent of small physical parameters, and thus it is suitable for most nonlinear problems. The HAM provides us a great freedom to choose basis functions of solution series, so that a nonlinear problem can be approximated more effectively, and it adjusts and controls the convergence region and the convergence rate of the series solution through introducing auxiliary parameter and the auxiliary function. The HAM hews out a new approach to the analytical approximate solutions of capillary flow in a circular tube. Through the specific example and comparing homotopy approximate analytical solution with the numerical solution which is obtained by the fourth-order Runge-Kutta method, the computed result indicate that this method has the good computational accuracy.
The modulational instability of the solition wave in two-dimensional Bose-Einstein condensates
Authors: Zhang Heng  , Duan Wen-Shan  ,   College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070, China
Published: December 2020

The solition wave in Bose-Einstein condensate with disk-shaped trap is investigated in this paper. Beyond the mean field, a two-dimensional nonlinear Schrödinger equation is obtained. The modulational instability for this system is studied analytically, and the growth rate for it is given.
First principles study on the electronic and optical properties of ZnO doped with rare earth
Authors: Li Hong-Lin  , Zhang Zhong  , Lü Ying-Bo  , Huang Jin-Zhao  , Zhang Ying  , Liu Ru-Xi  ,   School of Physics and Technology, University of Jinan, Jinan 250022, China;,   School of Space Science and Physics, Shandong University at Weihai, Weihai 264209, China
Published: December 2020

In this paper we use first-principles full potential linearized augmented plane wave method to investigate the band structure, density of states as well as the optical properties of ZnO, intrinsic and doped separately with Er and Gd. We find that dut to the carriers contributed by the introduced impurity atoms of rare earth (RE), the electrical conductivity of the system is improved and the Fermi level has an upward shift to the conduction band. The data show that due to the doping of RE, there appear the new electron occupied states around the Fermi level. This is formed by the states of Er-4f and Gd-4f. Meanwhile, intrinsic ZnO and doped structures are obviously different. For the optical properties, the absorption coefficient and reflectivity of rare earth doped ZnO are higher than those of intrinsic ZnO in visible region and the energy loss spectra of RE doped ZnO structure present red-shift.
Theoretical investigation on the spin-Hamiltonian parameters for Gd3+-doped molybdates AMoO4 (A=Ca, Sr, Ba, Pb)
Authors: Yang Wei-Qing  , Zhang Yin  , Gao Min  , Lin Yuan  , Zhao Xiao-Yun  ,   State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, China;,   Department of Photoelectric Technology, Chengdu University of Information Technology, Chengdu 610225, China
Published: December 2020

In this paper the spin-Hamiltonian parameters, g factors g//, g⊥ and zero-field splittings b20, b40, b44, b60, b64, for Gd3+ ion in molybdates AMoO4 (A=Ca, Sr, Ba, Pb) are calculated by a diagonalization (of energy matrix) method based on one-electron crystal field mechanism. The crystal field parameters in the matrix are calculated from the superposition model. The results indicate that seven calculated spin-Hamiltonian parameters are in good agreement with the experimental values by using only three reasonable adjustable parameters (i.e., the intrinsic parameters Ak (R0), where k=2, 4, 6, in the superposition model). It is shown that the diagonalization method can be used to calculate and explain the spin-Hamiltonian parameters of Gd3+ ion in crystals. The results are discussed.
Formation mechanism of ternary NiAl-Mo eutectic alloy under quenching condition
Authors: Bian Wen-Hua  , Dai Fu-Ping  , Wang Wei-Li  , Zhao Yu-Long  ,   Department of Applied Physics, Northwestern Polytechnical University, Xi’an 710072, China
Published: December 2020

The rapid solidification of ternary NiAl-Mo eutectic alloy is investigated by using melt-spinning technique, and the conventional casting is also carried out for a comparison study. The phase constitutions of the alloy samples obtained from different experiments each include both B2-NiAl intermetallic and bcc-Mo solid solution, which are both presented in the 〈110〉priority growth direction. The growth orientation relationship of the coupled two eutectic phases are obtained to be (110)NiAl//(110)Mo. The cast alloy is composed mainly of two regular eutectic phases in structure and exhibits daisy-like eutectic cells. However, the melt-spinning ribbons show the microstructures of the columnar grain near the roller surface zone and the equiaxed grain near the air zone. With the wheel speed increasing from 10 m/s to 50 m/s, the cooling rate of the alloy ribbons increases from 1.01×107 K/s to 2.46×107 K/s, while the thickness of alloy ribbons decreases from 49.4 μm to 22 μm. Meanwhile, the volume fraction of columnar grain zone increases gradually, and the grains are refined obviously. The cooling rate in the melt-spinning experiment for alloy ribbon is obviously higher than that in the conventional casting test, which leads to a significant difference in solidification microstructure between two techniques.
Phase-field-crystal modeling for two-dimensional transformation from hexagonal to square structure
Authors: Gao Ying-Jun  , Luo Zhi-Rong  , Huang Chuang-Gao  , Lu Qiang-Hua  , Lin Kui  ,   College of Physics Science and Engineering, Guangxi University, Nanning 530004, China
Published: December 2020

The two-mode phase-field-crystal (PFC) method is used to calculate the phase diagram and to simulate the transformation of hexagonal to square structure in two dimensions. The nucleation, grain growth and dynamic feature of the phase structure transformation show that square phase prefers to be present at the juncture place of the three hexagonal grains, and swallows the hexagonal phase at grain boundary. The square grains grow and push the boundary of hexagonal grain toward the inside of hexagonal grain and then the square grains grow up and extend the area of square phase. The orientations of new square grains due to the structure transformation are nearly randomly distributed, and have no relation to those of hexagonal grains. The dynamic curve of area fraction of square phase shows the typical S shape with time increasing. The Avrami index curve shows that there are two stages in the transformation. The Avrami index n of second satge in simulation is in a range from 2.0 to 3.0, which is in good agreement with the value from the JMAK theory.
Dissociation of H2 on Al7- cluster studied by ab initio calculations
Authors: Li Wen-Jie  , Yang Hui-Hui  , Chen Hong-Shan  ,   College of Physics and Electronic Engineering, Northwest Normal University, Key Laboratory of Atomic and Molecular Physics & Functional Materials of Gansu Province, Lanzhou 730070, China
Published: December 2020

With the accurate ab initio method, the adsorption and dissociation process of H2 molecule on Al7- cluster anion are investigated. The stable structures of molecular adsorption and dissociative adsorption are confirmed. The photoelectron spectra of different structures are further analyzed. The calculations indicate that the adsorption of H2 on Al7- is weak physical adsorption with the adsorption energy about 0.02 eV. The investigation of the dissociation process shows that the energy barrier of dissociation is about 0.75 eV. The densities of states of the Al7- cluster and the dissociative adsorption complex Al7H2- are in good agreement with those obtained by the photoelectron spectroscopy. It suggests that H2 can be dissociated when it is absorbed on Al7- anions produced by laser ablation.
Research status and application on the focusing properties of cylindrical vector beams
Authors: Zhao Wei-Qian  , Tang Fang  , Qiu Li-Rong  , Liu Da-Li  ,   Key Laboratory of Photo-electronic Imaging Technology and System, Beijing Institute of Technology, Beijing 100081, China
Published: December 2020

Cylindrical vector beams are spatially inhomogeneously polarized, whose intensity in the center is zero, and can produce special field components in the vicinity of focus when they are focused by an objective lens. In the case of optical system with high apodization factor, radial polarization can achieve tight focus by adapting pupil filtering and image restoration technology compared with linear and circular polarization. The properties of cylindrical vector beams are introduced. Based on electric dipole radiation model and vector diffraction theory, focal field properties for cylindrical vector beams focused by a high-NA objective lens are discussed. The method to achieve tight focus by cylindrical vector beams is presented. Furthermore, we consider it feasible for the super resolution laser polarized differential confocal microscopy by adapting the differential confocal microscopy, and put forward the prospective development.
Few-layer graphene membrane as an ultrafast mode-locker in erbium-doped fiber laser
Authors: Feng De-Jun  , Hang Wen-Yu  , Jiang Shou-Zhen  , Ji Wei  , Jia Dong-Fang  ,   School of Information Science and Engineering, Shan Dong University, Jinan 250100, China;,   College of Physics and Electronics, Shandong Normal University, Jinan 250014, China;,   College of Precision Instrument and Optoelectronics Engineering, Tianjin Uniuersity, Tianjin 300072, China
Published: December 2020

Single-layer graphene film is fabricated on the copper foil by using chemical vapor deposition method, and the corresponding Raman spectrum is measured. The graphene membrane is transferred to the facet of zirconium oxide of a fiber jumper. The mode-lock Er-doped fiber laser with few-layer graphene membrane as saturable absorber is experimentally studied, which has a ring structure and uses a 10% portion of a fiber coupler as the laser output. The laser generates a pulse train at a 7.69 MHz repetition rate, with a full width at half maximum of 58.8 ps. The corresponding time-bandwidth product is 1.98, indicating that the pulses are chirped. The peak wavelength and 3 dB bandwidth of the laser are 1560.1 nm and 0.27 nm respectively. Through changing the air gap between two the fiber ends, 4 nm wavelength tuning is observed.
High energy dissipative soliton mode-locked fiber oscillator based on a multipass cell
Authors: Xie Chen  , Hu Ming-Lie  , Zhang Da-Peng  , Chai Lu  , Wang Qing-Yue  ,   Ultrafast Laser Laboratory, College of Precision Instruments and Opto-electronics Engineering, Key Laboratory of Opto-electronics Information Technology (Ministry of Education), Tianjin University 300072, China
Published: December 2020

To investigate the energy scaling level of large-mode-area photonic crystal fiber-based dissipative soliton mode-locked fiber oscillators under limited pump power, a multipass cell is inserted in the cavity to lower the repetition rate of the system, and thus higher single energy level can be mapped under the same average power level. High energy mode-locked fiber lasers based on two spectral filters with different bandwidths are demonstrated both working in the all-normal dispersion regime at a repetition rate of 15.58 MHz. Employment of filters with FWHMs of 6nm and 12 nm can achieve stable mode-locked pulses with average powers of 3.73 W and 4.9 W, corresponding to single pulse energies as high as 239 nJ and 314 nJ, respectively. The FWHM durations of the dechirped pulses by a transmission grating pair can reach 56 fs and 75 fs, which can generate pulses with peak powers exceeding 3MW in both cases.
Intercomparison of slant column measurements of NO2 by ground-based MAX-DOAS
Authors: Wang Ting  , Wang Pu-Cai  , Yu Huan  , Zhang Xing-Ying  , Zhou Bin  , Si Fu-Qi  , Wang Shan-Shan  , Bai Wen-Guang  , Zhou Hai-Jin  , Zhao Heng  ,   Key Laboratory of Middle Atmosphere and Global Environment Observation, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China;,   University of Chinese Academy of Sciences, Beijing 100049, China;,   National Satellite Meteorological Center, China Meteorological Administration, Beijing 100081, China;,   Department of Environmental Science and Engineering, Fudan University, Shanghai 200433, China;,   Key Laboratory of Environmental Optics and Technology, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China
Published: December 2020

In September 2011, we used 3 ground-based multi-axis differential optical absorption spectroscopy (MAX-DOAS) instruments of different designs and operation protocols to measure tropospheric NO2 for about 20 days, at the Station of Atmospheric Comprehensive Observatory, Institute of Atmospheric Physics, Chinese Academy of Sciences (Xianghe 117.0N, 39.77E). All instruments are oriented to an azimuth angle of 270 (north), in a common wavelength range and with a set of cross sections for the inversion of NO2 slant column in visible and UV wavelength range respectively. Intercomparison of NO2 slant columns among three MAX-DOAS is introduced. The results obtained from the different instruments are in good accordance with each other, and the correlation coefficients are all higher than 0.95, but systematical errors exist. Daily average errors of three MAX-DOAS instruments are almost below 6%, showing that the instruments work steadily and the data are cogent. The UV results are smaller than those in the visible range, especially on the overcast days, related to the wavelength dependence of Rayleigh and Mie scattering. After the correction of systematical errors, there is better consistency among different results, which indicates that the three MAX-DOAS instruments have a capability to validate the atmospheric component products of satellite.
Optimized digital micro-holographic imaging system
Authors: Wang Hua-Ying  , Liu Fei-Fei  , Liao Wei  , Song Xiu-Fa  , Yu Meng-Jie  , Liu Zuo-Qiang  ,   Scholl of Information & Electrical Engineering, Hebei University of Engineering, Handan 056038 China;,   College of Science, Hebei University of Engineering, Handan 056038, China
Published: December 2020

Based on the analysis of the recording and reconstructing of hologram and the point spread function of pre-magnification digital micro-holographic system (PMDMHS), the performances of the six common PMDMHSs are compared in imaging resolution, imaging quality and conveniences, for the first time to our knowledge. The results show that the digital image-plane holography (DIPH) has the highest imaging resolution and the best imaging quality; the resolution of DIPH is independent of the photosensitive surface size of the recording device; this system can completely record the information about the object transmitted through the micro-objective (MO); it is not needed to consider the size of illuminated region of object. Moreover, the reconstruction process of DIPH is very simple. DIPH is an optimized digital holographic imaging system. The DIPH with equal curvature of reference wavefront and object wavefront is very conducive to phase unwrapping and phase aberration compensation; therefore DIPH is more suitable for phase microscopy. The experimental results demonstrate the validation of the theoretical analysis.
Micromagnetic simulation of magnetization reversal on the annular free layer with nick in magnetic random access memory
Authors: Hao Jian-Hong  , Gao Hui  ,   School of Electric and Electronic Engineering, North China Electric Power University, Beijing 102206, China
Published: December 2020

Based on magnetic tunnel junctions (MTJs), the magnetic random access memory with the pseudo-spin value film model, the annular structure with slanted cuts is used as free layer and the way to vary coercivity by changing thickness is discarded. With this improvement, the area resistance of the MTJs is reduced. The analysis of the cuts on the annular layer generated from the secondary effects of deposition in the IC process, is made by the micromagnetic simulations. The magnetization reversal characteristics from the analysis reveal the properties of low crosstalk, low RA, high magnetic reluctance, and strong anti-interference.
Mechanical stress in superconducting coils during winding process
Authors: Li Lan-Kai  , Wang Hou-Sheng  , Ni Zhi-Peng  , Cheng Jun-Sheng  , Wang Qiu-Liang  ,   Institure of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190, China;,   Graduate University of Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

In order to increase the filling factor of conductor in superconducting coils and improve the mechanical stability of superconducting magnet, the pre-tension is always applied to the conductor during winding the coils. Because the winding pre-tension has a great effect on the quench and degradation performance of superconducting magnet, it is necessary to analyze the mechanical stress caused by the fabrication. First, the winding physical process of conductor is analyzed. Then the theoretical model is developed to calculate the winding stress of superconducting coils based on some reasonable assumptions and approximations. And some formulas used for stress and strain are derived from the theory of elastic mechanics. Two kinds of superconducting coils (one consists of one type of wire, and the other one consists of two types of wires.) are researched according to the model. The effects of winding pre-stress and material anisotropy on radial stress and hoop stress in superconducting coils are also analyzed. On the basis of the analyzed results, one can further research the stress and strain of superconducting coils under the effect of multiphysics and give some theoretical suggestions for the design and construction of superconducting coils.
Mechanism of target wave excited by current with diversity
Authors: Hu Bo-Lin  , Ma Jun  , Li Fan  , Pu Zhong-Sheng  ,   Department of Physics, Lanzhou University of Techology, Lanzhou 730050, China
Published: December 2020

The formation of target wave in the network of Hodgkin-Huxley neuron with four variables is investigated by inputing a distribuled current. A stimulus current (I1) is input in to a local square area, and another stimulus current (I2) is input into the nodes of the network thus the distributed current is depicted. The development of target wave is measured by changing the coupling intensity, the size (number of the controlled neurons) of the local area into which current I1 is input, the gradient current (I =I1-I2). It is found that higher gradient current (I) is necessary to induce target wave when local area into which current I1 is input is smaller in size and the coupling intensity is higher in value. Finally, the potential mechanisms of the stimulus current and target wave formation are discussed in brief. Eextensive numerical results confirm that the developed target wave is robust to a certain channel noise.
Evaluation of Aetiology and Outcome of Acute Kidney Injury in a Tertiary Care Hospital of India- A Prospective Observational Study
Authors: Narayan VS Gaurav , Ramya SG , Kumar Sonal Rajesh , Ganesan SK Nellaiappa
Published: December 2020

Introduction: The Acute Kidney Injury (AKI) is a rapid decline in renal filtration function. The aetiological spectrum, prevalence of AKI and outcome is highly variable. This variation exists due to the difference in the criteria used, study population and demographic features. Huge differences are noted when AKI is compared in developing and developed countries. Hence, it is important to analyse the spectrum of AKI to facilitate earlier diagnosis and treatment which shall help in improving the outcome. Aim: To study the prevalence, aetiology and outcome of AKI in the medical intensive care. Materials and Methods: This was a prospective observational study conducted in a medical intensive care for 18 months where 1490 patients were screened and 403 patients were included as AKI by KDIGO criteria. History, examination, appropriate investigations and treatment details including dialysis were noted. The serum creatinine levels were obtained every day, to know the time of onset of AKI, at the time of death or discharge, and after one month for patients who turned up for follow-up. Patients were categorised based on outcome as survivors and nonsurvivors. Survivors were divided into as fully recovered and partially recovered and those who left the Intensive Care Unit (ICU) against medical advice were termed as lost to follow-up. Results: A total of 403 patients (27.04% of 1490) of medical intensive care admissions were found to have AKI. Sepsis was the most common cause of AKI. At the end of the month, 78.4% of AKI patients fully recovered, 1.2% partially recovered and the mortality was 14.9%. Mortality was higher in AKI associated with chronic medical conditions like cardiac failure, chronic liver disease and stroke. Conclusion: If treated early, AKI is mostly reversible. Regional differences in AKI should be studied extensively and local guidelines should be formulated by experts for prevention and early treatment, to improve the disease outcome.
Status of Aqua Drugs Applied in Freshwater Aquaculture of Moulvibazar District, Bangladesh
Authors: Singha Suranjit , Sultana Tasnim , Rima Nazmun Naher , Hasan Md. Robiul , Habib Ahsan
Published: December 2020

Aims: Our study aimed to assess the current situation of accessibility and the use of various chemicals and medicines in freshwater aquaculture.

Methodology: A questionnaire interview survey was conducted among 14 aquaculture farms and 23 aqua chemical retailers.

Results: Due to easy availability, farmers used large quantities of lime and cow dung to prepare ponds and manage water quality. Beside these rotenone, zeolite gold, acme’s zeolite, aqua kleen, urea and TSP (triple super phosphate) are also found. Timsen, polgard-plus, deltix, virex, magic-fos and pond-safe were mostly used as a disinfectant. Epizootic Ulcerative Syndrome (EUS) disease was found predominantly in the farmer's pond. For disease treatment, renamycine soluble powder (oxy tetracycline) was used, 32% farmers. Two oxygen suppliers oxy gold and oxy life were used to increase oxygen concentration. Among 11 types of growth promoters were found in chemical shops in which charger gel and rapid grow were mostly used. Most farmers use gas trap and gasonex plus as gas reducer.

Conclusions: There are mostly six categories of 48 aqua drugs and chemicals are observed and treated for health monitoring of fish and shellfish. Due to lack of knowledge concerning the proper dosage and procedure of using chemicals, technique of application and indiscriminate practice of chemicals etc. are common problems of aqua drugs in Moulvibazar district.
Survey of HIV/AIDS Knowledge and Behavior-Risk among in-School Adolescents and Youths in Ebonyi State, Nigeria
Authors: Chizoba A. F. , Chineke H. N. , Adogu P. O. U.
Published: December 2020

Adolescents and youths are at high risk due to knowledge gap and behavior risks related to HIV.

Despite the well-known need for protection from HIV infections and other reproductive health risks, being an adolescent coupled with social and economic status could limit access to information and services. This is a study to ascertain the HIV/AIDS Knowledge and behaviour-risk among in-school adolescents and youths in Ebonyi State, Nigeria.

It is a descriptive cross-sectional study involving1831 in-school adolescents selected by multi-stage sampling technique.

Females showed higher knowledge at 52.2±20.1 than males at 47.5±20.3 (p<0.001). Also the urban youths had higher knowledge (47.1±20.8) than rural schools (41.3±20.3). Conversely, males displayed higher behaviour risk at 44.8±24.5 than the female at 39.9±24.6 (p<0.001). Highest behaviour risk was observed in age group 16-20 years (51.2±25.8). Schools in urban setting had higher behaviour risk (56.1±25.5) than rural schools (41.3±23.7), while knowledge of HIV transmission was highest as 63.8% of the respondent scored ≥50 in 5 HIV questions on knowledge of transmission. Also 48% (370) of the 778 participants who ever had sex had used condom while 50% (915/1831) of the study population were willing to abstain from sex till marriage.

There is a strong need for appropriate regular and intensified HIV/AIDS risk reduction interventions to capture the attention of youths especially males, and to ensure sustainable and effective outcomes in secondary schools of Ebonyi state Nigeria.
FTIR Spectroscopy and Optical Density Characterization of Humic Substances Extracted from Reclaimed Alkali Soils under Different Tillage and Management Practices
Authors: Suman Shiva N. , Ahmed Nayan , Kumar Vipin , Datta Samar C. , Manjaiah K. M. , Kumar Rajesh , Kumari Vandana , Laik Ranjan , Das T. K.
Published: December 2020

In the present investigation, different tillage and management practices interventions were assessed to note the changes in the composition of humic substances using Fourier transform infrared (FTIR) techniques, optical density (E4/E6) measurement and elemental composition of humic acid. One uncultivated and four reclaimed alkali surface (0-0.15 m) soil samples after adoption of four years different tillage and management practices were collected from Central Soil Salinity Research Institute, Karnal. Optical density (E4/E6) of fulvic acid was higher than that of humic acid. This was due to the more condensed and more matured nature of humic acid than fulvic acid. The trend of E4/E6 ratio was farmers practices in rice-fallow-wheat cropping system with puddled rice and conventional tillage wheat without crop residue addition (FP in R-F-W) > integrated crop and resource management in rice-wheat-mungbean cropping system (ICRM in R-W-M)> futuristic and diversified (CA) based system of maize-wheat-mungbean cropping system (FDCA in M-W-M) >UnK> Conservation agriculture (CA) based system in rice-wheat-mungbean cropping system (CA in R-W-M). The highest stability was recorded in CA in R-W-M and the lowest in FP in R-F-W. Elemental composition of extracted humic acid revealed that carbon content in humic acid varied from 47.53% in uncultivated soils to 51.32% in ICRM in R-W-M. The nitrogen content in humic acid varied from 4.38% in FDCA in M-W-M to 4.89% in CA in R-W-M. Soils having the lowest C/N value was observed 10.03 in CA in R-W-M and the highest C/N ratio of value 11.72 was recorded in FDCA in M-W-M. Wave no.  (cm-1) & proposed functional group of extracted humic acid revealed that FTIR peak at 1507-1508 cm-1 in CA in R-W-M, aromatic -C=C- peak was absent in FDCA in M-W-M and in FP in R-F-W it was replaced by aliphatic C-H stretch.