bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of the concentration of heavily oxygen vacancy of rutile TiO2 on electric conductivity performance from first principles study
Authors: Hou Qing-Yu  , Wu Yun Ge Ri  , Zhao Chun-Wang  ,   College of Sciences, Inner Mongolia University of Technology, Hohhot 010051, China;,   Chemical Engineering Department, Inner Mongolia Vocational College of Chemistry Engineering, Hohhot 010071, China
Published: December 2020

The band structures and the total densities of states of pure and the different concentrations of heavily oxygen vacancy of rutile TiO2-x (x=0, 0.125, 0.25) supercell are studied by using the plane-wave ultrasoft pseudopotential method based on the the density functional theory. Local density approximation +U is used to correct band gaps. The results show that the higher the concentration of heavy oxygen vacancy, the narrower the gap of rutile TiO2 is, the smaller the effective mass of electron is, the lower the electron mobility is, and the lower the electron conductivity is. The calculation results are in agreement with the experimental results.
Numerical study of surface plasmon polariton coupling on the metal-insulator hybrid gratings
Authors: Chen Yong-Yi  , Qin Li  , Tong Cun-Zhu  , Wang Li-Jun  ,   State Key Laboratory of Luminescence and Application, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130089, China;,   University of Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

Surface plasmon polaritons can localize the photons near the metal surface, forming a strong near-field energy density, which affects the efficiency of illumination for molecules and the coefficient of utilization for optical-voltage materials near the metal surface. We analyze the absorption spectrum for the metal-insulator hybrid structure grating and give out the surface plasmon coupling condition according to structure and filling factor. We prove that when filling factor is high enough to form a tiny gap between grating elements, the efficiency for photons to be coupled into surface plasmon polaritons can reach above 94%.
Proximity-effect-induced superconductivity by granular Pb film on the surface of Bi2Te3 topological insulator
Authors: Ding Yue  , Shen Jie  , Pang Yuan  , Liu Guang-Tong  , Fan Jie  , Ji Zhong-Qing  , Yang Chang-Li  , Lü Li  ,   Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Acadeny of Sciences, Beijing 100190, China
Published: December 2020

The appearance of topological insulators provides us with a chance of finding topological superconductors and Majorana fermions. To pursue these findings one might need to induce large areas of proximity superconductivity on the surface of Bi2Te3 by depositing granular and discrete Pb film. In this experiment, a superconducting state over a distance of 9.5 rm is observed below 0.25 K on a Bi2Te3 crystal whose surface is deposited with Pb grains with a thickness of less than 20 nm and separated at a distance of 20-30 nm.
Influences of strain on electronic structure and magnetic properties of CoFe2O4 from first-principles study
Authors: Huang You-Lin  , Hou Yu-Hua  , Zhao Yu-Jun  , Liu Zhong-Wu  , Zeng De-Chang  , Ma Sheng-Can  ,   School of Materials Science and Engineering, Nanchang Hangkong University, Nanchang 330063, China;,   School of Materials Science and Engineering, South China University, Guangzhou 510641, China;,   School of Sciences, South China University, Guangzhou 510641, China
Published: December 2020

Spinel ferrites, such as CoFe2O4, can be used in various fields such as computer technology, aerospace, and medical biotechnology due to their good electromagnetic properties. Although, CoFe2O4 thin films have good application prospects in the magnetoelectric composites, the effects of strain on the electronic structure and magnetic properties of cobalt ferrite film have not been reported. Through the use of two-dimensional strain model closer to the epitaxial growth experiments, the films of Cobalt ferrite are simulated on various substrates with a realistic biaxial strain model by first-principles plane-wave pseudopotential method based on density functional theory, and combined with the generalized gradient approximation in the paper. And the structural stabilities, electronic structures and magnetic properties of CoFe2O4 films are studied. The results show that the inverse spinel is still energetically favored under strain, but the energy difference decreases, thus Fe3+ions in the tetrahedral sites and Co2+ ions in the octahedral sites are easier to exchange their positions. As the strain increases, the band gap of cobalt ferrite becomes narrower, and the magnetic moment of atom in the lattice changes, while the net magnetic moment changes little.
A pair of high resolution magnetic tweezers with illumination of total reflection evanescent field and its application in the study of DNA helicases
Authors: Wang Shuang  , Zheng Hai-Zi  , Zhao Zhen-Ye  , Lu Yue  , Xu Chun-Hua  ,   Beijing National Laboratory for Condensed Matter Physics, CAS Key Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
Published: December 2020

The resolution of conventional magnetic tweezers is limited by the Brown motion of magnetic beads. When the force is lower than ～10 pN, the resolution of magnetic tweezers decreases significantly because of the increased Brown motion. To improve the resolution of magnetic tweezers under low forces, we combine the total internal reflection fluorescence techniques with magnetic tweezers, and design a novel single molecule connection: magnetic bead-DNA linker-fluorescent bead-single molecule. With the improved magnetic tweezers, we study the folding dynamics of a DNA hairpin. The results reveal that a nanometer-scale resolution is obtained. By analyzing these results, we calibrate the penetration depth of the total internal reflection field. Finally, we investigate the unwinding dynamics of a BLM helicase core protein. Some preliminary results of the helicase unwinding experiments confirm the practicability of the improved magnetic tweezers in the field of single molecular research.
Performance of polycrystal silicon color solar cells
Authors: Jia He-Shun  , Luo Lei  , Li Bing-Lin  , Xu Zhen-Hua  , Ren Xian-Kun  , Jiang Yan-Sen  , Cheng Liang  , Zhang Chun-Yan  ,   Shandong Linuo Solar Power Holdings Co., Ltd, Jinan 250103, China;,   Nuclear and Radiation Safety Monitoring Center of Shandong Province, Jinan 250117, China
Published: December 2020

One layer SiNx:H films with different thickness are deposited by plasma enhanced chemical vapor deposition to prepare several kinds of polycrystalline silicon color solar cells. The optical and electrical properties are tested by instruments and simulated by PC1D. And the analysis shows that 1) when the antireflection film thickness is less than 50 nm, the deficiencies of color solar cells and solar modules are mainly influenced by open circuit voltage (Voc) and short circuit current (Isc); when the antireflection film thickness is greater than 50 nm, the passivation of H ions is stable and the deficiencies are mainly influenced by Isc; 2) the efficiency of most color solar cells is lower than that of blue ones, but the color solar cell will have some gains after packaging, which is because of the better optical matching of reflective film with ethylene-vinyl acetal copo and glass.
Modeling and analysis of vehicle behavior at bottlenecks
Authors: He Zhao-Cheng  , Sun Wen-Bo  , Zhang Li-Cheng  , Xu Fei-Fei  , Zhuang Li-Jian  ,   Research Center of Intelligent Transportation System, Sun Yat-Sen University, Guangzhou 510006, China
Published: December 2020

Microscopic traffic models are developed to simulate traffic phenomena. However, current models are usually based on the fact that vehicles travel in the middle of a single lane and make a lateral movement only when the driver wants to change lane. They are incapable of describing driving behavior in a complex traffic environment with a lot of lateral separations which may cause traffic flow to be unstable on a single lane. In order to solve the problem, in this paper we first build up the equations of motion based on target steering angle (TSA) and then establish a series of rules for determining TSA by considering the lateral separation characteristics between the follower and the leader. Finally a new vehicular behavior model is developed. The properties of the model are investigated by simulating two scenarios. It is found that the proposed model is capable of describing complex phenomena which cannot be described by existing models and explaining the perturbation caused by bus near bus stations. The results also imply that this model with taking the lateral separation characteristic into account greatly enhances the effectiveness of vehicular behavior.
Homotopic approximate solutions for a class of generalized perturbed Kdv-Burgers equation
Authors: Hong Bao-Jian  , Lu Dian-Chen  ,   Faculty of Science, Jiangsu University, Zhenjiang 212013, China;,   Department of mathematical and physical science, Nanjing Institute of Technology, Nanjing 211167, China
Published: December 2020

A class of generalized disturbed KdV-Burgers equation is studied by constructing a homotopy mapping. Based on the kinked solitary-wave solution of the corresponding typical undisturbed generalized KdV-Burgers equation with nonlinear terms of any order,the approximate solution with arbitrary degree of accuracy for the disturbed equation is researched. It is pointed out that the series of approximate solution is convergent. Finally,the efficiency and accuracy of the approximate solutions is also discussed by using the fixed point theorem.
The homotopy analysis method for a class of jamming transition problem in traffic flow
Authors: Han Xiang-Lin  , Ouyang Cheng  , Song Tao  , Dai Sun-Sheng  ,   Faculty of Science, Huzhou Teachers College, Huzhou 313000, China
Published: December 2020

Using the homotopy analysis method (HAM), the nonlinear equation of the jamming transition problem (JTP) in traffic flow is discussed, which is based on the Lorentz system. Through choosing different initial approximation solutions and different linear operators, approximation solutions of the JTP and the corresponding residual errors are obtained respectively. By comparing the present results with the previous related studies, the following conclusions can be drawn that the HAM is superior to the differential transform method; however, a linear operator should be chosen as best you can to approach the linear part of the original operator in using the HAM. A new method to choose the initial approximation solution (named double HAM) is given. The correctness of the theoretical analysis is verified by numerical simulation.
A new data assimilation method using complex-variable differentiation
Authors: Cao Xiao-Qun  , Song Jun-Qiang  , Zhang Wei-Min  , Zhao Yan-Lai  , Liu Bai-Nian  ,   School of Computer Science, National University of Defense Technology, Changsha 410073, China
Published: December 2020

A new method for data assimilation is proposed using complex-variable differentiation (CVD), which can be used to estimate the initial conditions of the nonlinear physical system governed by the following equation:. Firstly, the gradient analysis of cost function in variational data assimilation is transformed into function numerical computation in complex domain, and the value of gradient is computed more efficiently and exactly. Secondly, the new algorithm of data assimilation is developed by combining an accurate gradient information from CVD with the classical optimization method. Finally, numerical simulations of typical chaotic systems and a humidity evolution equation with physical on-off process show that the new data assimilation method can reconstruct initial conditions of the nonlinear dynamical system very conveniently and accurately.
Construction of a class of chaos systems with Markov properties
Authors: Liu Quan  , Li Pei-Yue  , Zhang Ming-Chao  , Sui Yong-Xin  , Yang Huai-Jiang  ,   State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China;,   Graduate School of Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

In this article, a kind of piecewise expanding linear system is constructed. It has a positive Lyapunov exponent as calculated. It is proved that the system has a uniform limit distribution The formula of the least period of the system is also presented. It is indicated that there is a contradictory relationship between the complexity and the least period of the system when the symbol entropy is applied to the system. The theoretical limit of the complexity of the system with changing parameters is presented. Simulation of the system shows that the sequence generated by the chaos is uniformly distributed. It also tells that the system can have higher complexity but longer least-period than the logistic system and the Tent-Map system. Experiments show that the system is suitable for constructing the cipher.
Compound bursting in an electrical coupling model with three different time scales
Authors: Yang Zhuo-Qin  , Zhang Xuan  ,   School of Mathematics and Systems Science and LMIB, Beihang University, Beijing 100191, China
Published: December 2020

Synchronization of bursting activities in pancreatic islets when pancreatic β-cells are coupled together by gap junctions plays an important role in the insulin secretion. A minimal and generic phantom bursting model proposed by Bertram et al is employed to produce compound bursting synchronization with anti-phase spikes of two electrical coupling pancreatic β-cells, where the membrane exhibits a transition between a burst episode composed of a long burst and several short bursts and a relatively long rest state with large amplitude on both sides but small at the middle. Two different fast/slow analyses for the moderate and the slower slow variables in three-dimensional spaces are combined to highlight better how these two slow variables with different time scales commonly or separately result in complex dynamics of the compound bursting of the two electrical coupling β-cells. Especially for the compound bursting synchronization with anti-phase spikes, more is stressed on how varying coupling strengths lead to a change of the number of the short bursts within the burst episode of different compound bursting.
A new method to directly observe the state of a single-variable nonlinear system with oscilloscope
Authors: Chen Hong  , Wu Ling  , Gu Shu-Bin  , Yang Kai  ,   Electronic Engineer College, Heilongjiang University, Harbin 150080, China
Published: December 2020

In order to solve the problem why it was hard to observe the single-variable nonlinear system, this article proposed the 45 line method. In this method, the continuous signal changing with time was transformed into dots on the 45 line of the rectangular coordinates, so that it could be directly displayed on a general dual-trace oscilloscope (either analog or digital). In this way, it is convenient to directly observe and analyze various states of single-variable system while the system is running, such as the periodical stable states, the local and global non-stable states. The mechanism of this method was expounded in this paper. In addition, the key issues in physical circuit design and implementation of this method were researched and solved, i.e., the useful signal which reflected the state of the system could be extracted from the continuously changing signal. Since the Chuas circuit is a typical nonlinear system, and it could produce abundant states with variation of parameters, so it was chosen as the system under test to conduct a great number of physical experiments. The experimental results confirmed the effectiveness and practicability of this method.
Uncertainty analysis of the measured spectrum obtained using transmission grating spectrometer
Authors: Shang Wan-Li  , Zhu Tuo  , Kuang Long-Yu  , Zhang Wen-Hai  , Zhao Yang  , Xiong Gang  , Yi Rong-Qing  , Li San-Wei  , Yang Jia-Min  ,   Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

Transmission grating spectrometer is applied in the area of inertial confinement fusion and other laser plasma interaction experiments. Accurate spectrum estimation depends on the measurement uncertainty. Based on the transmission grating diffraction efficiency calibration experiments, the uncertainty of diffraction efficiency is analyzed. Then the uncertainty of X-ray spectrum unfolding progress is investigated. The total uncertainty of the measured spectrum is obtained for 0.1 to 5 keV.
Experimental research on the technique of magnetic flux compression by explosive cylindrical implosion
Authors: Gu Zhuo-Wei  , Luo Hao  , Zhang Heng-Di  , Zhao Shi-Cao  , Tang Xiao-Song  , Tong Yan-Jin  , Song Zhen-Fei  , Zhao Jian-Heng  , Sun Cheng-Wei  ,   Institute of Fluid Physics, Chinese Academy of Engineering Physics Mianyang 621900, China
Published: December 2020

The cylindrical magnetic flux compression by explosive implosion (MC-1) is a kind of unique high energy density dynamic technique. A metal cylinder was driven by explosive implosion to compress the primary magnetic flux inside and an ultrahigh magnetic field was realized, which could be used to achieve effective isentropic compression of the sample. This technique has anigue characters like ultrahigh isentropic pressure and ultrahigh magnetic field, and would find wide usage in areas like high pressure physics, new material synthesis and ultrahigh magnetic field physics. The Institute of Fluid Physics, Chinese Academy of Engineering Physics (IFP, CAEP) has begun to make experiments on MC-1 since 2011 and a one-stage MC-1 set-up has been built up. The primary experimental results including the movement of liner and typical turn-around character in MC-1 experiment were observed and recorded. In the experiment a dynamic magnetic field of about 430T was obtained. The MC-1 process was numerically simulated by the one-dimensional MHD code and the simulations are in accord with experiments. Numerical simulations show that this technique has advantages in isentropic compression of materials as compared with normal implosion experiment.
Noether-Lie symmetry and conserved quantities of Nielsen equations for a singular variable mass nonholonomic system with unilateral constraints
Authors: Xu Chao  , Li Yuan-Cheng  ,   College of Physics, China University of Petroleum (East China), Qingdao 266580, China
Published: December 2020

Under the infinitesimal transformations of Lie group, Noether-Lie symmetry of Nielsen equations for a singular variable mass nonholonomic system with unilateral constraints is studied. Differential equations of motion for Nielsen equations of the system are established. The definition, criteria and propositions for Nielsen equations of the system are given. Noether conserved quantity as well as generalized Hojman quantity is obtained. An example is given to illustrate the application of the results.
X-ray emission of C6+ pulsed ion beams of CSR impacting on Au target
Authors: Zhang Xiao-An  , Mei Ce-Xiang  , Zhao Yong-Tao  , Cheng Rui  , Wang Xing  , Zhou Xian-Ming  , Lei Yu  , Sun Yuan-Bo  , Xu Ge  , Ren Jie-Ru  ,   Ion beam & Optical Physical joint Laboratory of Xianyang Normal University and Institute of Modern Physics, Chinese Academy of Sciences. Xianyang 712000, China;,   Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China
Published: December 2020

As the C6+ ion beam pulses, provided by the Heavy Ion Research Facility in Lanzhou-Cooling Storage Rings, impact on Au taget surface, the Lα-and Lβ-X spectra of Au atom are measured. Results show that the production cross section of Lα is larger than that of Lβ. The production cross sections increase with the kinetic energies of the projectiles. The PWBA and ECPSSR theoretical models are compared with the experimental resulms. The significant difference between experimental data and theoretical models was discussed.
Restrain the spurious resonance of second-order fractal frequency selective surface in MMW band
Authors: Xia Bu-Gang  , Zhang De-Hai  , Meng Jin  , Zhao Xin  ,   Key Lab. of Microwave Remote Sensing, Center for Space Science and Applied Research, Chinese Academy of Sciences, Beijing 100190, China;,   University of Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

Based on analyzing the equivalent circuit and electric field distribution of second-order square fractal frequency selective surface (FSS), the mechanism of its spurious resonance is discussed. To achieve a millimeter wave (MMW) spatial filter which exhibits high out-band suppression(≥13dB) and insensitive to the variation of oblique incident angles for both TE and TM polarized waves, a hybrid methodology of decoupling operation in conjunction with discrete particle swarm optimization (DPSO) procedure is proposed. The FSS array without spurious resonance and its evolutionary process by DPSO are described. It is also demonstrated that the measured results and DPSO-operated frequency characteristics are in excellent agreement.
Analytical vectorial structure of Airy-Gaussian beam
Authors: Deng Xuan-Bing  , Deng Dong-Mei  , Chen Chi-Dao  , Liu Cheng-Yi  ,   Laboratory of Laser Sports Medicine, South China Normal University, Guangzhou 510006, China;,   Laboratory of Nanophotonic Functional Materials and Devices, South China Normal University, Guangzhou 510006, China
Published: December 2020

Based on the vector angular spectrum of the electromagnetic beam and the method of stationary phase, the analytical vectorial structure of the Airy-Gaussian beam in the far field has been presented. According to the analytical electromagnetic representations of the TE and TM terms, the energy flux distributions of the TE term, the TM term, and the whole beam in the far field are investigated respectively. The formulas obtained are applicable not only in the paraxial case, but also in the nonparaxial case. The physical pictures of Airy-Gaussian beams are well illustrated from the vectorial structure, which may provide a new approach to manipulate laser beams.
Eye movement analysis for activity recognition based on one web camera
Authors: Meng Chun-Ning  , Bai Jin-Jun  , Zhang Tai-Ning  , Liu Run-Bei  , Chang Sheng-Jiang  ,   Institute of Modern Optics, Nankai University, Tianjin 300071, China;,   School of Electronics and Information Engineering, Tianjin Polytechnic University, Tianjin 300387, China
Published: December 2020

Eye movement information is the key clue for recognizing the vision-dominated tasks, such as browsing the web, or watching a video. However, traditional wearable sensors are invasive and the vision-based eye trackers are very expensive and need time consuming calibration. Therefore, an activity recognition method based on eye movement analysis under one web camera is first proposed and the feasibility is assessed. First, an iris tracking method for the low quality image is proposed to acquire eye movement information. Then, five ten novel features are extracted from the horizontal and the vertical eye movement signals for activity recognition, and the optimal feature subset is selected. Finally, the support vector machine is used to assess the feasibility of the proposed method. Three experiments are designed for different applications: leave-one-out cross-validation, k-fold cross-validation, and validation after respective calibration. Experimental results show that their accuracies are 68.4%, 79.3% and 84.1%, respectively, which demonstrate the promise of eye based activity recognition using one web camera.
Theory of complex ridgelet transform based on the entangled state
Authors: Yu Hai-Jun  , Zhong Guo-Bao  , Ma Jian-Guo  , Ren Gang  ,   Department of Physics and Electronic Information Engineering, Huinan normal colledge, Huainan 232038, China;,   Shool of Physics and Material Science, Anhui University, Hefei 230039, China
Published: December 2020

Based on the results of constructing the wavelet transform in continuous variable quantum state and the classical continuous ridgelet transform, we construct the continuous complex ridgelet transform in the expression of quantum operators and representations. We study the theory of the complex ridgelet transform in quantum optic state via calculating the inner product and projection of quantum states.
Entanglement properties of two coupled atoms in Kerr medium
Authors: Wu Qin  , Zhang Zhi-Ming  ,   Laboratory of Nanophotonic Functional Materials and Devices (SIPSE), South China Normal University, Guangzhou 510006, China;,   School of Information Engineering, Guangdong Medical College, Dongguan 523808, China
Published: December 2020

We have investigated the entanglement time evolution of two coupled two-level atoms in Kerr medium. Entanglement of the system is calculated by making use of concurrence. The influences of initial state, Kerr medium, and dipole-dipole coupling intensity between two atoms on the entanglement degree of the two atoms are revealed. Results show that the appropriate choice for the nonlinear coupling constant of Kerr medium and the dipole-dipole coupling intensity can improve the degree of atom-atom entanglement and eliminate the entanglement sudden death completely. We also find that invariant and stable entanglement occurs for a particular initial state.
Experimental characterization of polarization gain properties of 808nm semiconductor laser and analysis of energy band based on amplified spontaneous emissions from double facets
Authors: Ma Ming-Lei  , Wu Jian  , Yang Mu  , Ning Yong-Qiang  , Shang Guang-Yi  ,   Department of Applied Physics, Beihang University, Beijing 100191, China;,   State Key Laboratory of Luminescence and Application, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China
Published: December 2020

The information of optical gain of semiconductor lasers can be obtained through the amplified spontaneous emission from double facets. By utilizing this new approach, an experimental research about polarization (TE and TM) gain characteristics of continuously-operated 808 nm GaAs/AlGaAs quantum well laser is introduced in this paper. Through the measured gain spectra which are compared with the theoretical gain curves, we analyze the variations of hole subband corresponding to the polarizations along with the change of injection current, meanwhile the actual status of gain spectra and influential factors of the continuously-operated laser are discussed as well.
Study the coupling effect of shear and electric field on rheological behaviors of liquid crystals
Authors: Qiao Xiao-Xi  , Zhang Xiang-Jun  , Tian Yu  , Meng Yong-Gang  , Wen Shi-Zhu  ,   State Key of Laboratory Tribology, Tisnghua University, Beijing 100084, China
Published: December 2020

The rheological behaviors of 5CB liquid crystal under the coupling effect of shear and electric field are investigated by theoretical and experimental study. Establish calculating equation of the system Gibbs free energy by adopting the continuum theory of liquid crystals which contains anchoring energy, elastic free energy, dielectric free energy and flow energy. Then the molecular orientation angle distribution and apparent viscosity of liquid crystal under the coupling effect are obtained by minimizing the Gibbs free energy, revealing the microscopic mechanism of rheological behaviors and influence rules of coupling effect from the molecular model. Meanwhile the calculated results are verified by rheological test. Comparative Analysis of the errors and reasons of theoretical and experimental results, which demonstrates that anchoring effect plays an important role in the molecular orientation and viscosity of liquid crystal. Both the theoretical and experimental results indicate that liquid crystals have electroviscous effect and behavior like non-Newtonian liquids under electric field. The viscosities of liquid crystals are determined by the coupling and competition action of shear and electric field, which can reach 4 times of its original value under electric field. This property of controllable viscosity is important in tribology, which can self-adaptively satisfy the requirement of viscosities for different working conditions as a "smart lubrication" under certain condition.
Molecular simulations of adsorption and separation of natural gas on zeolitic imidazolate frameworks
Authors: Guo Hai-Chao  , Shi Fan  , Ma Zheng-Fei  , Zhou Zhi-Wen  , Zhou Yi-Ran  ,   State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemistry and Chemical Engineering, Nanjing University of Technology, Nanjing 210009, China;,   URS Corporation, PO Box 618, South Park, PA, USA.;,   National Energy Technology Laboratory, U.S. D.O.E., 626 Cochrans Mill Road, Pittsburgh, PA, USA.;,   Navi Health and Environment Technology, Pittsburgh, PA, USA.
Published: December 2020

Grand canonical Monte Carlo simulations were employed to investigate the adsorption and separation of C2H6, CO2 and CH4 on two zeolitic imidazolate frameworks (ZIF-2 and ZIF-71). The adsorption isotherm and isosteric heat of pure gas, the separation performance of C2H6-CH4, CO2-CH4 and C2H6-CO2 binary mixtures and C2H6-CO2-CH4 ternary mixtures on two ZIFs were simulated and discussed. For single component gas adsorption at a low pressure, the adsorption amount depended on isosteric heat; at a high pressure, due to the limited pore volume, ZIFs preferably adsorbed smaller size gas molecules. For gas mixture separation, energetic effect dominated at low pressure, therefore, ZIFs selectively adsorbed gas component with strong interactions; packing effect usually played an important role at high pressures, consequently, smaller size component would be more entropically favorable. Results demonstrated that both ZIF-2 and ZIF-71 were of good separation performance for these three binary mixtures. For the ternary mixture separation, it was found that ZIF-2 cowld effectively separate C2H6 and CO2 from CH4 at 3000-4000 kPa and room temperature.
Plasmonic excitations in mesoscopic-sized atomic chains：a tight-binding model
Authors: Xin Wang  , Wu Reng-Lai  , Xue Hong-Jie  , Yu Ya-Bin  ,   School of Physics and Microelectronics Science, Hunan University, Changsha 410082, China
Published: December 2020

Plasmonic excitations in mesoscopic-sized atomic chains are investigated by employing the tight-binding model. Based on the quantum response theory and random phase approximation, a plasma oscillation eigen-frequency equation is derived for calculation of the plasmon energy spectrum. The plasmon energy spectrum has been numerically calculated, and the eigen-oscillation of the system and the resonance behavior under the external electric field applied on the atom chain are investigated, respectively. Dependence of plasmonic excitation energy on the length of systems and electron density has been discussed. Results suggest that in the case of resonance, the resonant peak of dipole moment is corresponding to the plasmonic excitation, and this indicates that the external electric field excites the plasmon of the system. In resonance the oscillation amplitude of the charge is much larger than that in the case of non-resonance, especially the imaginary part of the charge has a more obvious enhancement. For the eigen-oscillations, the plasmonic excitation energy is greater than the single-particle excitation state at the same level; the length of atomic chains, the electron density, and the strength of Coulomb correlation have significant effects on the plasmon spectroscopy. For the given atom-chain length, with variation of number of electrons, the plasmonic excitation energy varies symmetrically around the half-filling. This indicates that the plasmon spectrum of the system is symmetrical for the electrons and holes.
Preparation of nanostructured GaN films and their field emission enhancement for different substrates
Authors: Chen Cheng-Cheng  , Liu Li-Ying  , Wang Ru-Zhi  , Song Xue-Mei  , Wang Bo  , Yan Hui  ,   Laboratory of Thin Film Materials, College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124, China;,   College of Applied Sciences, Beijing University of Technology, Beijing 100124, China
Published: December 2020

Using pulsed laser deposition (PLD) method, we have prepared nanostructured GaN films of the same thickness on Si and SiC substrates, and analyzed their microstructure characterization and field emission properties. The results showed that the substrates of GaN nanostructured films had significant effect on the microstructure and field emission properties. Compared with the GaN nano-film on Si substrate, the field emission from the GaN nano-film on SiC substrate has been significantly improved: its field emission current was increased by orders of magnitude. The field emission enhancement should be originated from the nanocrystalline microstructure and its orientation polarization induced field enhancement effect. Results indicate that to prepare field emission films of outstanding performance, appropriate substrates and crystal microstructures of the films are the key issues.
Broad band infrared optical properties of Cr4+-doped Li1.14Zn1.43SiO4 transparent glass-ceramics
Authors: Ma Hong-Ping  , Liu Ping  , Yang Qing-Hua  , Deng De-Gang  ,   Colllege of Materials Science and Engineering, University of Shanghai for Science and Tecnology, Shanghai 200093, Chian;,   School of Mechanical & automotive Engineering, Zhejiang University of Science and Technology, Hangzhou 310012, China;,   College of Materials Science and Engineering, China Jiliang University, Hangzhou 310018, Chian
Published: December 2020

Cr4+-doped transparent Li1.14Zn1.43SiO4 glass-ceramics were prepared by high-temperature melting and subsequent heat-treatment, and the crystalline, microstructural, and luminescence properties of the products prepared by different-temperature heat-treatment were investigated. Results showed that the glass-ceramics heat-treated at 580 ℃ for 2 h contained nano crystallines of about 5 nm in size, and a broadband infrared emission centered at 1226nm with full width at half maximum of more than 230 nm and a decay time of about 200.07 s were observed by exciting with an 808 nm laser diode. Mean while, it is believed that the crystalline field environment of Cr4+ is changed with the increase of heat-treatment temperature, which results in blue shift and red shift of absorption and fluorescence spectra, respectively.
Study on microstructure and properties of Mg2(Si,Sn) compound phase in Mg-Sn-Si magnesium alloy
Authors: Zhang Jian-Xin  , Gao Ai-Hua  , Guo Xue-Feng  , Ren Lei  ,   Institute of Materials Science and Engineering, Henan Polytechnic University, Jiaozuo 454000, China;,   Institute of Liberal Arts and Law, Henan Polytechnic University, Jiaozuo 454000, China;,   Institute of Mechanical and Power Engineering Henan Polytechnic University, Jiaozuo 454000, China
Published: December 2020

Microstructure, characteristic and metamorphism of Mg2(Si,Sn) compound phase are studied in as-cast Mg-Sn-Si alloy. The results indicate that Sn atom can replace the partial Si of Mg2Si then form Mg2(Si,Sn) compound phase, and structure of the ternary compound is the same as Mg2Si and Mg2Sn, all belong to face-centered cubic. The element content of Mg2(Si,Sn) phase is not invariable, the Mg2(Si,Sn) phase with high Si content is in Si enrichment region, while it with low Si content is in Si poverty region. The property of Mg2(Si,Sn) phase with high Si content is close to Mg2Si phase, the property of the phase with high Sn content is close to Mg2Sn phase. In experiments, the nano-hardness, elastic modulus, vickers hardness and other physical properties of Mg2(Si,Sn) phase are between Mg2Si phase and Mg2Sn phase, in the metamorphism process of Chinese-script-like Mg2Si phase, Mg2(Si,Sn) compound phase plays a role as a bridge.
High-precision CO2 and 13CO2 analysis
Authors: Li Xiang-Xian  , Xu Liang  , Gao Min-Guang  , Tong Jing-Jing  , Jin Ling  , Li Sheng  , Wei Xiu-Li  , Feng Ming-Chun  ,   Key Laboratory of Environment Optics and Technology, Chinese Academy of Sciences, Hefei 230031, China
Published: December 2020

An instrument based on Fourier transform infrared spectrometer is developed, which is capable of simultaneously measuring carbon dioxide (CO2) and 13CO2 in a single air sample with higher precision. The temperature and pressure effect on the values of CO2 and 13CO2 are investigated. Both the standard gas and air sample gas are continuously measured using this method. Precision and accuracy are improved by comparing with the measurements of standard gas after correction using the law of temperature and pressure effect on the values of CO2 and 13CO2.
Approximate time-dependent solution of Fokker-Planck equation with non-linear drift force
Authors: Yang Hui-Hui  , Ning Li-Juan  ,   College of Mathematics and Information Science Shaanxi Normal University, Xi’an 710062, China
Published: December 2020

In this paper, the unstable state evolution problem of the non-linear dynamical system driven by Gaussian white and colored noise is investigated. Using the eigenvalue and eigenvector theory, the expression of the approximate time-dependent solution (ρ(x, t)) is derived. The effects of parameters on ρ(x, t), mean and normalized variance are also analyzed. Numerical simulations show that 1) ρ(x, t) is a monotonic function of t and x under the certain limits of t, which increases with τ increasing, but decreases with α increasing; it is very remarkable for large τ and large α; 2) the mean of the state variable x is positive, which increases with τ increasing, but decreases with α increasing; the normalized variance of the state variable x is a non-monotonic function of the α and τ. Therefore, a phase transition phenomenon is found in this system.
Gamma-distributed maximum a posteriori despeckling algorithm of high-resolution synthetic aperture radar images
Authors: Sun Zeng-Guo  ,   College of Computer Science and Technology, Huaqiao University, Xiamen 361021, China
Published: December 2020

In order to solve the problem that the traditional Gamma-distributed maximum a posteriori despeckling algorithm cannot effectively preserve the point target in the homogeneous region, nor effectively keep the weak edge, and nor efficiently suppress the speckle in the strong edge region, the Gamma-distributed maximum a posteriori despeckling algorithm with prior parameter estimation based on second-kind statistics is proposed for high-resolution synthetic aperture radar images. Using the Mellin convolution and the multiplicative model of speckle, the parameters of the Gamma prior distribution are accurately estimated from the first two log-cumulants of the observed image. The proposed algorithm has the analytical filtering output, and it is easy to implement. Despeckling experiments on high-resolution synthetic aperture radar images of agricultural field and urban region demonstrate that compared with the traditional Gamma-distributed maximum a posteriori despeckling algorithm, the proposed one can effectively preserve the point target in the homogenous region, effectively retain the weak edge, and efficiently suppress the speckle in the strong edge region.
Calibration of pressure to 35 GPa for the cubic press using the diamond-cemented carbide compound anvil
Authors: Wang Hai-Kuo  , He Duan-Wei  , Xu Chao  , Liu Fang-Ming  , Deng Ji-Rui  , He Fei  , Wang Yong-Kun  , Kou Zi-Li  ,   Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, China
Published: December 2020

In the present study, we analyse the mechanical structure for the two-stage anvil cell, and design the two-stage high pressure cell using diamond-cemented carbide compound as anvil-material. The diamond-cemented carbide compound material is synthesized using the 6×2500 ton cubic press in our laboratory. We sinter diamond/Co layer (Φ30 mm×10 mm) on a WC-cobalt substrate (Φ30 mm×13 mm) at high pressures and temperatures, then, we obtain the cubic anvils from the sintered cylindrical chunks by wire-electrode cutting. The diamond-cemented carbide compound anvil has three advantages over the traditional sintered diamond anvil: first, a scaled-up version of the sintered diamond anvil could be obtained by sintering the diamond/Co layer on a WC-cobalt substrate; second, the diamond-cemented carbide compound anvil is machined easily compared with the sintered diamond anvil; and third, the experimental cost using the diamond-cemented carbide compound anvils is much lower than using the sintered diamond anvil. Using the diamond-cemented carbide compound anvil, we design the two-stage 5.5/1.5 (octahedral edge-length/anvil truncation edge-length, in millimetre) assemble. Pressure calibration at room temperature is performed for the 5.5/1.5 assemble using the phase transitions of Zr (α-ω, 7.96 GPa; ω-β, 34.5 GPa) under high pressures. The pressure range of the two-stage apparatus besed on hinge-type cubic press is extended from 20 GPa to about 35 GPa using the 5.5/1.5 assemble. The pressure calibration for the two-stage apparatus using diamond-cemented carbide compound anvil is ongoing in our laboratory. We believe that the pressures above 50 GPa could be achieved using these anvils.
Laser Doppler shift measuring method based on phase modulater and Fabry-Perot interferometer
Authors: Du Jun  , Zhao Wei-Jiang  , Qu Yan-Chen  , Chen Zhen-Lei  , Geng Li-Jie  ,   National Key Laboratory of Science and Technology on Tunable Laser, Harbin Institute of Technology, Harbin 150080, China
Published: December 2020

A different method of laser Doppler shift measurement is proposed. By using the sinusoidal phase-modulation, the plus and minus one-order sidebands beside the original frequency component in signal light are generated. And a beat frequency signal with fixed-frequency is present when the amplitude and phase of the modulated light are turned with Fabry-Perot interferometer. The characteristic of the amplitude of this beat frequency signal changing with the frequency is used to measure the Doppler shift. By theoretically analyzing, it can be concluded that this method can possess the advantages of both the normal coherent and non-coherent methods and also has the merits of high measuring accuracy and easy fabrication. The validity and feasibility of this method are verified experimentally, and its measurement accuracy is found experimentally to be one order of magnitude higher than that of the normal non-coherent method.
Application of machine vision to the measurement of the effective d31 coefficient in laser interferometry
Authors: Lai Zhi  , Guo Liang  , Li Xiao-Zhen  , Dang Wen-Jia  ,   School of Physics Optoelectronic Engineering, Xidian University, Xi’an 710071, China
Published: December 2020

A novel method based on machine vision is proposed for measuring the effective d31 coefficient. Based on the best estimation of gray scale of interference pattern, the sensitivity of the twin-beam interferometry is significantly improved in comparison with previously reported system. Firstly, the interference pattern grabbed by machine vision system is extracted using the algorithm developed in this work. Secondly, using gray-scale pattern with 256 gray-levels the measurement accuracy of the interferometric optical path difference of the interferometer can reach 1/1024 of the wavelength of the laser theoretically. So the experimental results of a PZT pipe in the method are greatly accurate.
Slow light based on stimulated Brillouin scattering in microstructured fiber
Authors: Wei Wei  , Zhang Xia  , Yu Hui  , Li Yu-Peng  , Zhang Yang-An  , Huang Yong-Qing  , Chen Wei  , Luo Wen-Yong  , Ren Xiao-Min  ,   State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876, China;,   State Key Laboratory of Optical Communication Technologies and Networks, Optical Fiber Department of Fiberhome Telecommunications Technologies Co. Ltd, Wuhan 430074, China
Published: December 2020

All-optical tunable slow light technology has promising applications in all-optical network and optical information process. Tunable slow light based on stimulated Brillouin scattering is experimentally investigated, using highly nonlinear microstructured fiber which is designed and drawn by ourselves. The experiment setup is composed of single pump and a single-stage delay. When the pump power reaches 162.6 mW, a maximum delay of 76 ns, equal to 0.76 pulse width, is achieved in the highly nonlinear microstructured fiber of 120 m in length. In addition, by adjusting the pump power, the tunable slow light can be realized. This scheme of slow light has advantages such as large delay, being all-optical tunable and compatible with optical communications systems.
Crystallization behavior and kinetics mechanism of 20GeS2·80Sb2S3 chalcogenide glass
Authors: Yang Zhi-Qing  , Wang Fei-Li  , Lin Chang-Gui  ,   Laboratory of Infrared Materials and Devices, Ningbo University, Ningbo 315211, China
Published: December 2020

Knowledge of crystallization behavior and kinetics mechanism is essential to achieve the controllable crystallization. Surface crystallization of 20GeS2·80Sb2S3 chalcogenide glass is realized using differential scanning calorimeter technique and heat treatment method. An about 40 μm thick Sb2S3 crystal layer is precipitated after heat treatment at 268℃ (Tg+30℃) for 60 h. Then, non-isothermal method is employed to theoretically analyze the crystallization kinetics of this glass sample. Crystallization activation energy Ec is calculated to be (223.6±24.1) kJ·mol-1, and crystallization rate constant K at 268℃ was obtained to be 1.23×10-4 s-1, indicating that the crystallization of 20GeS2·80Sb2S3 glass is more difficult than that of other chalcogenide glass system, such as GeS2-Ga2S3. The crystal growth index, m and crystal growth dimensionality, n both are equal to 2, which suggests that the crystallization of Sb2S3 glass phase is of 2D growth process. This work would contribute to the fabrication of Sb2S3 crystallites embedded chalcogenide glass-ceramics.
The progress of silicon-based grating couplers
Authors: Yang Biao  , Li Zhi-Yong  , Xiao Xi  , Nemkova Anastasia  , Yu Jin-Zhong  , Yu Yu-De  ,   National Key Laboratory for Optoelectronic Integration, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
Published: December 2020

Silicon-based photonic integrated chips recently have attracted great attention and actively intervened in many applications such as optical communications, optical interconnects, and optical sensing for relevant research institutions. Photonic integrated circuits are the key block to build information infrastructures. Among of them, grating couplers play an important role in silicon photonics, due to high efficient optical coupling on/off photonic chips. Also, they have many advantages in high density photonic packaging and on-wafer testing, such as large alignment tolerances and no requirements for wafer scribing or chip polishing. This review focuses on the principles and performances of grating couplers on silicon-on-insulator substrates. In this article, we also discuss the state-of-art and the trends in the near future, with a summary of our achievements over the last few years.