bluuebunny/crossref_metadata_2025 huggingface dataset:
Ordered mesoporous antireflective films for 1053 nm high power pulse laser
Authors: Sun Jing-Hua  , Xu Yao  , Yan Liang-Hong  , Lü Hai-Bing  , Yuan Xiao-Dong  ,   Key Laboratory of Carbon Materials, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001, China;,   Laser Fusion Research Centre, Chinese Academy of Engineering Physics, Mianyang 621900, China;,   Graduate University of the Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

Single-layer silica films are prepared via evaporation-induced-self-assembling process using triblock copolymer surfactant F127 as template and tetraethoxysiliane as precursor under acidic condition. After ammonia pretreatment, the as-deposited films undergo a thermal decomposition process to remove the surfactant, and the mesopores are formed in film. Three techniques are used to characterize the mesoscopic structure of film, i.e., grazing-incidence X-ray diffraction, nitrogen adsorption/desorption and transmission electron microscopy. The results indicate that the film has an ordered cage-like porous structure and can be indexed as the body-centered-cubic arrangement. The optical properties of the films are investigated via ellipsometry and UV-VIS-NIR transmission spectrometer. The transmitance can reach up to 99.9% at 1053 nm wavelength. The refractive index varies with the molar ratio of F127/Si. Atomic force microscope is used to probe the surface morphology, and the surface roughness Ra is 1.2 nm. A 1053 nm laser is used to determine the laser damage threshold of film and all the thresholds are higher than 25 J· cm-2 (1 ns). This method has a potential application in the preparation of large-aperture antireflective films.
Electronic structures and dielectric properties of BaCoxZn2-xFe16O27 from first principles
Authors: Ri Chung-Ho  , Li Lin  , Qi Yang  ,   Department of Physics, Northeastern University, Shenyang 110819, China;,   Department of Physics, University of Science, Pyongyang, D.P.R. of Korea;,   Institute of Materials Physics and Chemistry, Northeastern University, Shenyang 110819, China
Published: December 2020

On the basis of the crystal structure model of BaCoxZn2-xFe16O27 , their ground electronic states and dielectric properties have been investigated using the generalized gradient approximation plus Hubbard U approach. The co-substitutions of cobalt and zinc cause the electrical conductivity of BaFe18O27 to change from a half-metallic to semiconductive. With the increase of Co content x, the energy gap of BaCoxZn2-xFe16O27 increases but the lattice constants and the magnetic moment of the unit cell decrease. The calculations of dielectric constants show that the static dielectric constants increase with x, lie in a range of 6.2-7.2 and appear to be anisotropic. Through the Born electric charge analysis it is shown that the polarization of Co and Zn itself has little effect on the polarization of the material and the main polarization may be related to the polarization of the iron and oxygen ions, caused by the crystal distortion.
Investigation on the current collapse effect of AlGaN/GaN/InGaN/GaN double-heterojunction HEMTs
Authors: Yu Chen-Hui  , Luo Xiang-Dong  , Zhou Wen-Zheng  , Luo Qing-Zhou  , Liu Pei-Sheng  ,   Jiangsu Key Laboratory of ASIC Design, Nantong University, Nantong 226019, China;,   College of Physics Science and Technology, Guangxi University, Nanning 530004, China;,   School of Remote Sensing, Nanjing University of Information Science and Technology, Nanjing 210044, China
Published: December 2020

A series of AlGaN/GaN/InGaN/GaN double-heterojunction high-electron-mobility-transistors (DH-HEMT) is fabricated with GaN channel layer thicknesses from 6 nm to 20 nm by two-dimensional (2D) numerical simulations. A new idea for optimizating of DH-HEMT structure is proposed. The hot electron effect and self-heating effect are investigated by using hydrodynamic model. Current collapse and negative differential conductance are observed to be directly relevant to GaN channel layer thickness. DH-HEMT with thicker GaN channel layer can confine electrons better in channel, which significantly diminishes the penetration ability of hot electrons from channel layer to buffer layer under high voltage. Increasing the thickness of GaN channel layer appropriately can effectively restrict current collapse and negative differential conductance, and consequently improve device performance under high voltage condition.
Properties of rapidly rotating hybrid stars with non-Newtonian gravity
Authors: Fu Hong-Yang  , Wen De-Hua  , Yan Jing  ,   Department of Physics, South China University of Technology, Guangzhou 510641, China
Published: December 2020

The properties of rapidly rotating hybrid stars are calculated and discussed with an equation of state considering non-Newtonian gravity (described by the Yukawa contribution). The said properties include the mass-radius relationship, the Kepler rotating frequency, the moment of inertia, the gravitational redshift and the ratio of the rotational energy to the gravitational energy. It is shown that at the Kepler frequency, the maximum stellar mass increases up to about 20% compared with that from the static model at the same central density. It is also shown that for a rapidly rotating hybrid star, the rotation has an obvious influence on the bulk properties, such as the mass-radius relationship, the moment of inertia, the ratio of the rotational energy and gravitational energy, but has a faint effect on the polar gravitational redshift.
Atomic entropy squeezing of the Jaynes-Cummings model driven by classical fields in non-Markovian environment
Authors: Cai Cheng-Jun  , Fang Mao-Fa  , Xiao Xing  , Huang Jiang  ,   Department of Physics, Hunan Normal University, Changsha 410081, China;,   College of Physics and Electronics, Gannan Normal University, Ganzhou 341000, China
Published: December 2020

The atomic entropy squeezing of the Jaynes-Cummings model driven by classical fields in non-Markovian environment is investigated according to the non-Markovian quantum theory and the entropy squeezing theory. Our attention is focused on the influences of the non-Markovian effects, the Rabi frequencys of classical fields and the detuning on the atomic entropy squeezing. And we explain the atomic entropy squeezing dynamic by the memory effects of the non-Markovian processes. It is found that the atomic entropy squeezing can be maintained for a long time when both the Rabi frequencys of classical fields and the non-Markovian effect are present simultaneously. And we can obtain the optimal squeezing states by choosing appropriate parameters of the Rabi frequency and the detuning of classical field. Our results provide a potential method of generating high-degree squeezed and longtime atomic squeezing states by controlling the atom-field interaction.
Dynamic modeling and analysis of a bistable piezoelectric cantilever power generation system
Authors: Sun Shu  , Cao Shu-Qian  ,   School of Mechanical Engineering, Tianjin University, Tianjin 300072, China;,   Tianjin Key Laboratory of Nonlinear Dynamics and Chaos Control, Tianjin 300072, China
Published: December 2020

Dynamic modeling and analysis of a bistable piezoelectric cantilever power generation system are presented. Firstly, a magnetic force model is established which could induce bistability, and the force mathematical expression between the two magnets is given. Secondly, a lumped parameter model of piezoelectric cantilever power generation system is built, and the range of distance between the two magnets is analyzed while the bistable phenomenon occurs. Thirdly, the response characteristics of the system are studied numerically. The results show that the beam undergoes large-amplitude motion at low frequency and low amplitude, and that the voltage response has a broadband. The system has high energy escaped from potential well when excitation amplitude imereases. Finally, the result is verified experimentally. This study provides a theoretical basis for the design and application of bistable piezoelectric cantilever power generation system.
Influences of axial position manipulation and misalignments of optical elements on radial trap position manipulation
Authors: Ren Hong-Liang  , Ding Pan-Feng  , Li Xiao-Yan  ,   College of Information Science and Engineering of Huaqiao University, Xiamen 361021, China
Published: December 2020

Optical tweezers in which a tightly focused laser beam is used to trap micron-sized or nanometer-sized particles have become indispensable tools for measuring the forces and displacements associated with molecular biomechanical events in a noninvasive manner. A complete beam manipulation system is composed of a beam expander input lens, beam expander output lens, focusing lens, piezoelectric translator mirror to control the trap position, with the overfilling degree of the objective entrance aperture retained. The accurate manipulations of trap position in three dimensions are the bases for the realization of the position clamp and force clamp. The optical path of optical tweezers based on infinity corrected conjugate microscope is calculated using matrix optics. The influences on radial trap position manipulation caused by axial position adjustment of focusing lens and objective, and by the installation location error of focusing lens and piezoelectric translator mirror are analyzed. The result shows that axial position adjustment of objective introduces a nominal error in radial trap position manipulation. The misalignments of focusing lens and piezoelectric translator mirror have a greater influence on optical tweezers performances. The theory points out the accurate dynamic axial position adjustment range, which is useful to optical tweezers design and experiments.
Theoretical calculation of the vib-rotational interaction potential and the differential coefficient cross sections for He-HD (HT, DT) system
Authors: Shen Guang-Xian  , Wang Rong-Kai  , Linghu Rong-Feng  , Zhou Xun  , Yang Xiang-Dong  ,   School of Physics and Electronic Sciences, Guizhou Normal University, Guiyang 550001, China;,   School of Chemistry and Material Science, Guizhou Normal University, Guiyang 550001, China;,   Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, China
Published: December 2020

The interaction potential surfaces of He-HD (HT, DT) are calculated by employing ab initio method at the CCSD(T)/AUG-CC-PV5Z +bf(3s3p2d1f) calculational level when the key-lengths of target-molecule are different. The vib-rotational interaction potentials of He-HD (HT, DT) system are fitted using the method of center of mass transformation-fitting, the Tang-Toennies potential function and nonlinear least square method at the incident angles of 0°, 20°, 40°, 60°, 80°, 90°, 100°, 120°, 140°, 160° and 180°. The differential coefficient cross sections at the energies of 60, 90 and 120 meV are calculated by using the quantum close-coupling method. On the basis of the above result, the change rules of the differential coefficient cross section with incident energy, reduced mass of system and scattering angle are discussed.
Physical model for activation of emission on silicon quantum dots
Authors: Huang Wei-Qi  , Huang Zhong-Mei  , Miao Xin-Jian  , Liu Shi-Rong  , Qin Chao-Jian  ,   Institute of Nanophotonic Physics, Key Laboratory of Photoelectron Technology and Application, Guizhou University, Guiyang 550025, China;,   State Key Laboratory of Ore Deposit Geochemistry Institute of Geochemistry, Chinese Academy of Sciencees, Guiyang 550003, China
Published: December 2020

The emission of silicon quantum dots is weaker when their surface is passivated well. Oxygen or nitrogen on surface of silicon quantum dot can break the passivation to form the localized electronic state in band gap to generate active center where the stronger emission occurs. In this way we can build up the radiative matter for emission. Controlling the surface bonds on silicon quantum dots, various wavelengths of emission can be obtained. The annealing is important for the treatment of the activation. Experiments demonstrate that the stimulated emissions at about 600 nm and 700 nm appear on active silicon quantum dots, and the photoluminescence peaks are found in a range from 1500 nm to 1600 nm.
Study of photonic crystal fiber with an air core
Authors: Zhao Xing-Tao  , Liu Xiao-Xu  , Zheng Yi  , Han Ying  , Zhou Gui-Yao  , Li Shu-Guang  , Hou Lan-Tian  ,   Measurement Technology and Instrumentation Key Laboratory of Hebei Province, State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004, China;,   Laser Institute of Science College, Beijing Jiaotong University, Beijing 100044, China;,   College of Physics and Chemistry, Hebei Normal University of Science and Technology, Qinhuangdao 066004, China
Published: December 2020

Photonic crystal fibers with an air hole in the core are analyzed by finite-element method. The relations of mode field distribution, confinement loss and dispersion characteristics with fiber structure parameter and wavelength are achieved. The principle of guiding light in air hole is explained by diffraction and the characteristics of photonic crystal fiber. For the fiber with low loss, single-mode, tightly confined light in the air core, the ranges of structure parameters and wavelengths are obtained. An optimal fiber structure is designed, of which the mode is tightly confined in the air core, and the confinement loss α=5.9× 10-5 dB/km. These provide theoretical instruction for the design and fabrication of photonic crystal fiber with an air hole in the core. The high intensity in an air hole, coupled with long interaction length, promises a new class of experiments in light-matter interaction and nonlinear fiber optics.
How to obtain q-profile from results of polarimeter
Authors: Jiao Yi-Ming  , Zhou Yan  , Li Yong-Gao  , Li Chang-Zheng  ,   Southwestern Institute of Physics, Chengdu 610041, China
Published: December 2020

A new method to obtain the q-profile and current density distribution from Faraday rotation angle measured by polarimeter is introduced. The large aspect-ratio hypothesis is taken into consideration in plasma equilibria discharge analysis. The q-profiles and current density profiles are obtained in Ohmic and ECRH discharges. The calculation results accord well with the soft X-ray measurements.
Study on high mobility In0.6Ga0.4As channel MOSHEMT and MOSFET
Authors: Chang Hu-Dong  , Sun Bing  , Lu Li  , Zhao Wei  , Wang Sheng-Kai  , Wang Wen-Xin  , Liu Hong-Gang  ,   Microwave Device and IC Department, Institute of Microelectronics, Chines Academy of Sciences, Beijing 100029, China;,   Institute of Physics, Chines Academy of Science, Beijing 100190, China
Published: December 2020

High-mobility In0.6Ga0.4As channel metal oxide semiconductor high electron mobility transistor (MOSHEMT) and metal oxide semiconductor field effect transistor (MOSFET) are investigated based on simulation and experiment in this paper. It is found that InAlAs barrier layer has a great influence on the characteristics of In0.6Ga0.4As MOSHEMT. In0.6Ga0.4As MOSHEMT exhibits excellent electrical characteristics compared with In0.6Ga0.4As MOSFET. The experimental results show that the effective channel mobility of MOSHEMT is 2812 cm2/V·s-1, which is 3.2 times that of MOSFET. A 0.02 mm gate length MOSHEMT shows higher drive current, peak transconductance, Ion/Ioff ratio and gate breakdown voltage and lower sub-threshold swing than the MOSFET with the same gate length.
Research on dielectric tunability of relaxor ferroelectrics
Authors: Shang Xun-Zhong  , Chen Wei  , Cao Wan-Qiang  ,   Key Laboratory of Ministry of Education for the Green Preparation and Application of Functional Materials, Faculty of Materials Science and Engineering, Hubei University, Wuhan 430062, China
Published: December 2020

Based on the high dielectric tunability, high dielectric constant and small dielectric loss at paraelectric phase, lead-free relaxor ferroelectrics have been used in microwave devises widely. According to the present theory of dielectric tunability, the expression of dielectric tunability is derived by adjusting parameters properly. The derived expression can be used to deal with experimental results. It is found that there exists a great difference between experimental result and the theoretical result obtained under the assumption of unchanged paraelectric phase under an electric field, while the experimental result and the theoretical result of Johnson in 1962 is consistent. A modified relation of dielectric constant with higher electric field is derived by considering the Gibbs free energy modified with an external electric field and a spontaneous polarization. The result from the modified equation is in agreement with the experimental result. A concept of degree of tunability is proposed to express quantitatively the relationship between dielectric tunability and concentration of dopants.
Bifurcation analysis for a delayed sea-air oscillator coupling model for the ENSO
Authors: Xu Chang-Jin  ,   Guizhou Key Laboratory of Economics System Simulation, Guizhou University of Finance and Economics, Guiyang 550004, China
Published: December 2020

In this paper, a delayed sea-air oscillator coupling model for the ENSO is investigated. We obtain the sufficient condition of stability in equilibrium. By choosing delay η as a bifurcation parameter, we show that Hopf bifurcation can occur when delay η passes through a sequence of critical values. Meanwhile, based on the center manifold theory and the normal form approach, we derive the formula for determining the properties of Hopf bifurcating periodic orbit, such as the direction of Hopf bifurcation, the stability of Hopf bifurcating periodic solution and the periodic of Hopf bifurcating periodic solution. Finally, numerical simulations are carried out to illustrate the analytical results.
Many-body quantum fluctuation effects of Rosen-Zener transition in Bose-Einstein condensates
Authors: Wang Jian-Zhong  , Cao Hui  , Dou Fu-Quan  ,   School of Physics Beijing Institute of Technology, Beijing 100081, China;,   National Key Laboratory of Science and Technology on Computation Physics Institute of Applied Physics and Computational Mathematics, Beijing 100088, China;,   HEDPS Center for Applied Physics and Technology Peking University, Beijing 100084, China
Published: December 2020

We investigate many-body quantum fluctuation effects of Rosen-Zener transition of Bose-Einstein condensate (BEC) in a symmetric double-well potential through the relation between the average population imbalance of the final state (APIFS) and scanning period. In the linear case, we deduce the analytical expression of the APIFS which has the same behavior as in the mean-field level. We also employ numerical calculation to demonstrate it. In the nonlinear case, numerical results show that the APIFS in the sudden limit also accords with that in the mean-field level whereas in the adiabatic limit the many-body result is quite different from that of the mean-field case: the behavior of APIFS with respect to scanning period is similar to sinusoidal rather than rectangular oscillation, besides the oscillation period increases with both the total number N and the nonlinear parameter c increasing.
Design of waveguide array frequency selective surface filter in sub-millimeter wave band
Authors: Cui Guang-Bin  , Miao Jun-Gang  , Zhang Yong-Fang  ,   School of Electronics and Information Engineering, Beijing University of Aeronautics and Astronautics, Beijing 100191, China
Published: December 2020

In order to meet the low insertion loss of transmission band and the low reflection loss of reflection band in detection technology of millimeter and sub-millimeter wave, in this paper, we design a frequency selective surface (FSS) filter based on waveguide array structure in the sub-millimeter wave band. Through optimizing the structural parameters, the FSS filter overcomes the drawback that the insertion loss increases at large angle of incidence. Meanwhile the FSS filter is not sensitive to the change of angle of incidence, these make it satisfy the requirements of particular engineering. In addition, the frequency responses of the FSS filter to TE and TM are the same, so it can detect the dual-polarized radiation signals simultaneously. Firstly, we give initial values of structural parameter according to the indicator. Secondly, we simulate and optimized the structure by simulation software. Finally, a new FSS filter with a low insertion loss is given. Simulation results show that the FSS filter meets the system requirements and overcomes the shortcoming of large insertion loss at a large incident angle. Then, we analyze the main source of the insertion loss in transmission band. An error sensitivity analysis of structural parameters of FSS filter is also given, which provides a reference for fabrication.
Hole doping effects on structure and magnetic properties of Sr2FeMoO6
Authors: Hu Yan-Chun  , Wang Yan-Wen  , Zhang Ke-Lei  , Wang Hai-Ying  , Ma Heng  , Lu Qing-Feng  ,   College of Physics and Information Engineering, Henan Normal University, Xinxiang 453007, China;,   Henan Province Key Laboratory of Photovoltaic Materials, Xinxiang 453007, China;,   Department of Life Science and Technology, Xinxiang Medical University, Xinxiang 453003, China
Published: December 2020

Samples of Sr2-xKxFeMoO6 (x=0, 0.01, 0.02, 0.03, 0.04) are prepared by standard solid-state reaction. The crystal structures and magnetic properties for the ordered double perovskite oxides Sr2-xKxFeMoO6 (0 x 0.04) are investigated. X-ray powder diffraction studies reveal that all the samples are of single phase and each of them has a I4/m symmetry. The anti-site defects in double perovskite oxides of Sr2FeMoO6 may be adjusted by alkali metal element of K doping. The unit cell magnetizations at 280 K are 1.12B for x=0.00 and 1.26B for x=0.04. The cation-ordering and the variation of structure parameters play improtant roles in determining the magnetism in the doping system.
Phase transition and thermal expansion properties of ZrV2-xPxO7
Authors: Yuan Huan-Li  , Yuan Bao-He  , Li Fang  , Liang Er-Jun  ,   School of Physical Science & Engineering and Key Laboratory of Materials Physics of Ministry of Education of China, Zhengzhou University,Zhengzhou 450052, China;,   North China University of Water Resources and Electric Power, Zhengzhou 450011, China
Published: December 2020

ZrV2-xPxO7 (x = 0, 0.4, 0.8, 1.0) solid solutions are prepared using a solid state reaction method. Powder X-ray diffraction (XRD) analysis reveals that the as-prepared solid solutions are of single-phase cubic type in crystal structure. Temperature dependent Raman spectroscopic studies demonstrate that the phase transition temperature of ZrV2-xPxO7 decreases with the increase of the content of P. ZrV2O7, ZrV1.6P0.4O7, ZrV1.2P0.8O7 and ZrVPO7 transform from a 3× 3× 3 superstructure to a 1× 1× 1 normal structure at about 373 K, 363 K 273 K and 213 K, respectively. The results of thermal expansion testing indicate that the temperature of positive thermal expansion changes to negative thermal expansion with the increase of P content. The temperatures of positive-to-negative thermal expansion of ZrV2-xPxO7 are 429 K, 403 K, 372 K, 390 K, 398 K and 435 K for x=0, 0.2, 0.4, 0.6, 0.8 and 1, respectively. Two phase change transformations are demonstrated in ZrV2-xPxO7 materials in our work, which is beneficial for preparing the negative thermal expansion materials at room temperature using ZrV2O7.
First-order and second-order infrared quantum cutting of Ho3+ Yb3+ doped oxyfluoride vitroceramics
Authors: Chen Xiao-Bo  , Yang Guo-Jian  , Li Song  , Sawanobori N.  , Xu Yi-Zhuang  , Chen Xiao-Duan  , Zhou Gu  ,   Applied Optics Beijing Area Major Laboratory and Analysis and Testing Center, Beijing Normal University, Beijing, 100875, China;,   Sumita Optical Glass, Inc., 4-7-25 Harigaya, Urawa, Saitama, 338, Japan;,   The Chemistry and the Molecular Engineer College, Peking University, Beijing 100871, China
Published: December 2020

Infrared quantum cutting is an international hot research field nowadays. Comparitive research between first-order and second-order quantum cutting of Ho3+ Yb3+ doped oxyfluoride vitroceramics is reported in present paper. It is found that most population can easily non-radiativly relax to (5F45S2) energy level when the energy levels between 5G5 and 5S2 are excited. For (5F45S2) level, the population of Ho3+ ion can be cross-transferred to 5I6 level by strong ETr7-ETaYb {5F4(Ho) 5I6 (Ho), 2F7/2(Yb) 2F5/2(Yb)} cross energy transfer passage; meanwhile, Yb3+ ion is excited to 2F5/2 level from 2F7/2 ground state. It results in the two infrared photons which can be absorbed by crystal Si, that is, one is (1153 nm, 1188 nm) infrared photon and the other is (973.0 nm, 1002.0 nm) infrared photon. Therefore, it results in two-photon first-order infrared quantum cutting. Finally, the cross energy transfer efficiency tr, 1%Yb(5F45S2)=29.2%, tr, 10.5%Yb(5F45S2)=99.2%. and cooperative energy transfer efficiency tr, 1%Yb(5F3)=4.18%, tr, 10.5%Yb(5F3)=75.3% of Ho(0.5)Yb(1):FOV and Ho(0.5)Yb(10.5):FOV are calculated. Their quantum efficiency up-limits of two-photon quantum cutting are CR, 1%Yb(5F45S2)=129.2%, CR, 10.5% Yb(5F45S2)=199.2 and CO, 1%Yb(5F3)=104.18%, CO, 10.5% Yb(5F3)=175.3% respectively. That is to say, the probability of first-order infrared quantum cutting is larger than that of second-order infrared quantum cutting. The present research is of significance for enhancing solar cell efficiency.
Forming efficiency of porous anodic oxide and formation mechanism of nanopores
Authors: Zhu Xu-Fei  , Han Hua  , Song Ye  , Ma Hong-Tu  , Qi Wei-Xing  , Lu Chao  , Xu Chen  ,   Key Laboratory of Soft Chemistry and Functional Materials, Ministry of Education, Nanjing University of Science & Technology,Nanjing 210094, China;,   National Engineering and Technology Research Center for ASIC Design, Institute of Automation, Chinese Academy of Sciences, Beijing 100190, China
Published: December 2020

Porous anodic alumina (PAA) and porous anodic TiO2 nanotubes have received considerable attention because of their applications in a number of fields. The formation mechanisms of nanopores and nanotubes in these porous anodic oxides, however, have remained unclear until now. The interactions between porous structural features and current-time transients in anodizing process cannot be successfully explained. Based on the mechanism of dielectric breakdown of the compact anodic alumina (CAA), the differences and internal relations in their forming processes between CAA and PAA are contrasted in detail. From this innovative standpoint, according to the divergence of PAA and CAA in their current-time curves (or voltage-time curves), two essential causes which induce the decrease of the forming efficiency of oxide in the anodizing process, that is, the generation of the electronic current and the oxygen evolution, are presented in the paper. The evidences of the round hollows within the CAA films, show that the regularly embryo pores result from the oxygen bubbles. According to the aluminum anodizing in the mixed-electrolyte, the results show that once oxygen evolution stopping, the pore growth must be stopped, and the pores must be sealed by the above compact oxide. A novel composite film of the anodic oxide is presented. All of the above conclusively show that in the forming process of PAA, an appropriate magnitude of electronic current ensures the oxygen evolution and the pores formation, an appropriate magnitude of ionic current ensures the oxide formation and growth of pore walls.
Fuzzy adaptive tracking control of uncertain chaotic system with input perturbance and nonlinearity
Authors: Li Ning  , Liu Heng  , Xiang Wei  ,   Department of Mathematics and Computional Science, Huainan Normal University, Huainan 232038, China
Published: December 2020

In this paper, we investigate the signal tracking problem of the uncertain time-varying delay chaotic system with control input nonlinearity and the fuzzy adaptive variable structure control method is proposed. The fuzzy logic system approximates the nonlinearity of the system. The unknown time-varying delay uncertainties are compensated using an appropriate Lyapunov-Krasovskii functional. The proposed controller can make the tracking errors converge to an adjustable region and all signals of the closed system is bounded. The designed control method can have a certain robustness against the disturbance of the system. Finally, taking the simulations on a multi-scroll chaotic system for example, the effectiveness of the proposed method is illustrated.
Technology of polarization interference imaging spectral based on pupil division and angle shear
Authors: Tang Qian  , Zhao Bao-Chang  , Qiu Yue-Hong  , Zhang Chun-Min  , Mu Ting-Kui  ,   Xi'an Institute Optics and Precision Mechanics, Chinese Academy of Sciences, Xi'an 710119, China;,   Graduate University of Chinese Academy of Sciences, Beijing 100049, China;,   The Key Laboratory of Non-Equilibrium Condensed Matter and Quantum Engineering of Ministry of Education, School of Science, Xi'an Jiaotong University, Xi'an 710049, China
Published: December 2020

With the combination of pupil division, Wollaston prism angle shear and Savart plate lateral shear interference, a new technology that can aquire the message of imaging, polarization and spectrum simultaneously is presented. The system works at the pushing mode with neither mechanical movable nor electrically tunable device, and four quarters of the single charge-coupled device can get four interferograms of different polarization states (two polarization-difference spectral imagings). The device is discussed in detail, and the relationship between azimuth of the prism principal cross section and the output light intensity is analyzed, and then system parameters are optimized. In the paper, we derive the interference fringe intensity distribution formula, use computer numerical simulation to verify the feasibility and accuracy of this method, and thus provide an important theory basis and the practice instruction for designing a new type of imaging spectrometer and its engineering applications.
Vectorial structure of a hollow Gaussian beam diffracted by a circular phase aperture in the far field
Authors: Lu Shi-Zhuan  , You Kai-Ming  , Chen Lie-Zun  , Wang You-Wen  , Yang Hui  , Dai Zhi-Ping  ,   Department of Physics and Electronic Information Science, Hengyang Normal University, Hengyang 421008, China
Published: December 2020

Based on the vector angular spectrum representation of the Maxwell equations and the method of stationary phase, only with the far field approximation, the analytical expressions of energy flux density of a hollow Gaussian beam diffracted by a circular phase aperture is presented. It is shown that the total energy flux of the beam can be expressed as the sum of the unapertured term and the additional term, where the additional term is the effect of the phase aperture on the beam; the total energy flux, the unapertured one and the additional one each can be expressed as the sum of TE term and TM term. The distributions of the total energy flux, the unapertuered one, the additional one, and their TE terms and TM terms are depicted in the far field. The influences of truncation parameter and the phase delay on the longitudinal total energy flux distributions are discussed.
Time influence factor of vanadium oxide nanotube on Si substrate and initial gas sensing test
Authors: Li Ming-Yang  , Yu Ming-Lang  , Su Qing  , Liu Xue-Qin  , Xie Er-Qing  , Zhang Xiao-Qian  ,   Department of Physics, Lanzhou University, Lanzhou 730000, China
Published: December 2020

Vanadium oxide nanotubes are prepared on a Si substrate with hydrothermal method in this experiment with dodecylamine serving as template. X-ray diffraction, Raman spectroscopy and scanning electron microscope (SEM) are employed to characterize the structural and electronic properties of these nanotubes. The results show that the growth of VOX nanotubes and their gas sensing properties are affected by the hydrothermal reaction time rather than mixing time. With longer reaction time, the VOX nanotubes display better properties with smoother walls, stronger gas sensitivity and faster response time (15 s), than with shorter reaction time. SEM results reveal that VOX nanotubes have inner diameters between 25-35 nm and outer diameters between 65-100 nm. The sample inner diameters vary between 25 and 35 nm. The outer diameters are also quite similar in all tubes and lie between 65 and 100 nm.
Synthesis and characterization of the Gem-diamond by temperature gradient method
Authors: Xiao Hong-Yu  , Su Jian-Feng  , Zhang Yong-Sheng  , Bao Zhi-Gang  ,   Department of Mathematics and Physics, Luoyang Institute of Science and Technology, Luoyang 471023, China
Published: December 2020

At pressure 5.0-5.7 GPa and temperature 1250-1600 ℃, the conditions of synthesis Gem-diamond are reported using FeNiMnCo catalyst by temperature gradient method (TGM), and the P-T phase diagram is given. Temperature field and carbon concentration gradient are simulated based on finite element method (FEM). The results of simulation and experiment show that type-I temperature field is suitable for growing high-quality large sheet-shaped Gem-diamond and small tower-shaped Gem-diamond; however, choosing type-II temperature field, both large sheet-shaped Gem-diamond and large tower-shaped Gem-diamond can be synthesized (type-Ib diamond and boron-doped diamond). On this basis, the growth speed and crystal quality are found to be determined by the carbon concentration gradient, and the rule that high-quality Gem-diamond can be synthesized when temperature field is suitable for the size and shape of diamond growing is given. The pressure and temperature regions for {110} and {113} faces to exist are studied. According to the analysis of Fourier infrared spectroscopy, it is found that the nitrogen concentrations in type-Ib and boron-doped diamonds synthesized by FeNiMnCo catalyst, which are due to the influence of Fe element, are lower than that of normal diamond. The diamond with low nitrogen can be used as an optical material with better transmission characteristics.
Resistometric study on electromigration failure in copper interconnects
Authors: Wu Zhen-Yu  , Dong Si-Wan  , Liu Yi  , Chai Chang-Chun  , Yang Yin-Tang  ,   Key Laboratory of Ministry of Education for Band-Gap Semiconductor Materials and Devices, School of Microelectronics, Xidian University, Xi'an 710071, China
Published: December 2020

A resistometric model based on microscopic analysis of electromigration failure mechanism is built. An extraction method for failure parameters of electromigration in copper interconnects is proposed from resistometric characteristics including the slope and step height. The results show that the failure time can be considered as the time to deplete grains at the cathode line end under a given stressing current. Two dominant failure modes with resuling slit and trench voids are observed in electromigration induced failures. The resistance curve for the trench-voiding failure mode consists of two characteristic regions,i.e., a step jump and an oblique line. The grain size and the extracted critical void length are lognormally distributed with close parameters. The variation in the slop of the oblique line in resistance curve with temperature obeys an exponential law. Activation energy of approximately 0.9 eV obtained from the resisometric model is consistent with that from Black equation.
Chaotic frequency-modulating continuous wave for an ultrasonic doppler blood flow velocity measurement system
Authors: Peng Jing-Si  , Peng Hu  ,   Department of Electronic science and Technology, University of Science and Technology of China, Hefei 230027, China;,   Department of Biomedical Engineering, Hefei University of Technology, Hefei 230009, China
Published: December 2020

Although a pulsed-wave (PW) Doppler system can measure blood velocity with range information, measurable velocity is limited by frequency aliasing, and signal-noise-ratio (SNR) is poor. Continuous wave (CW) Doppler system offers a higher SNR in Doppler signal and no measurable velocity limitations but does not provide ranging information. Linear frequency-modulated continuous wave (LFMCW) and sine frequency-modulating continuous wave are able to provide high SNR Doppler signals with ranging information, and low clutter power, but with a certain range ambiguity due to signal periodicity of the Doppler signal spectrum. Various efforts have been made to improve the SNR, range resolution, and velocity limitations with FMCW Doppler system. An ultrasonic doppler blood flow velocity measurement system based on chaotic FMCW is proposed which has a higher SNR with no range ambiguity because of the aperiodicity of the Doppler signal spectrum. Principle analysis and experimental simulation show that the effectiveness of the new system is verified.
A ring Ti:sapphire regenerative amplifier for high energy chirped pulse amplification
Authors: Zhang Wei  , Teng Hao  , Wang Zhao-Hua  , Shen Zhong-Wei  , Liu Cheng  , Wei Zhi-Yi  ,   Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
Published: December 2020

Based on chirped-pulse amplification technology, a ring cavity Ti:sapphire regenerative amplifier with high output energy is demonstrated. Under the 532 nm pump energy of 33.1 mJ at a repetition rate of 100 Hz, the chirped laser pulse with energy of 9.84 mJ is obtained, corresponding to a slope efficiency of 33.1%. Instead, using the pump laser with energy of 32.0 mJ at a repetition rate of 10 Hz, we also obtain 9.64 mJ pulse energy with a corresponding slope efficiency of 36.8%. By optimizing the dispersion among all optical materials, stretcher and compressor, the shortest pulse has an energy of 6.36 mJ and a pulse width of 59.7 fs, and the energy fluctuation is 1.85 % (RMS) over 4000 shots after the compressor. The performances show that it may pave the way for ultrafast applications and serves as a front stage toward TW even PW laser system with high contrast ratio.
A novel approach to research on feature extraction of seismic wave signal based on wireless sensor networks
Authors: Qi Hao  , Wang Fu-Bao  , Deng Hong  ,   School of Electronics and Information, Northwest Polytechnical University, Xi’an 710072, China;,   Microwise System Company Limited, Xi'an 710077, China
Published: December 2020

In order to solve the problems of high sampling rate which could shorten the lifetime of wireless sensor networks in wild relics security system, the power spectrum reprocessing is applied to the feature extraction of seismic wave signal. This method is used to solve the target recognition problem, and three data sets are used to verify its effectiveness. The result shows that the power spectrum reprocessing can reduce the communication consumption and prolong the lifetime of networks. This method can also increase the accuracy of target classification. This method, indicating its good performance, had been applied to wild relics security system of Museum of the Terra-cotta Warriors and Horses of Qin Shihuang.
First-principles study on the electronic structures of β-SiC/carbon nanotube core-shell structures
Authors: Zou Xiao-Cui  , Wu Mu-Sheng  , Liu Gang  , Ouyang Chu-Ying  , Xu Bo  ,   College of Physics and Communication Electronics, Jiangxi Normal University, Nanchang 330022, China
Published: December 2020

The structural and electronic properties of β-SiC/(15, 0) carbon nanotube (CNT) and β-SiC/(16, 0)CNT core-shell structure are studied by using first-principles method based on the density functional theory. The results show that the two heterostructures are metallic. Their metallic properties are contributed by the atoms from the CNTs and the surface of SiC nanowires. The metallic property of the SiC nanowire is determined by its structure. However, the fact that the metallic (15, 0) and semiconducting (16, 0) CNTs both show the metallic properties after filling the SiC nanowires, is due to not the deformation of CNTs, but the charge transfer between CNTs and SiC nanowires.
Investigation of photoionization of excited atom irradiated by the high-frequency intense laser
Authors: Tian Yuan-Ye  , Guo Fu-Ming  , Zeng Si-Liang  , Yang Yu-Jun  ,   Institute of Atomic and Molecular Physics, Jilin University, Changchun 130012, China;,   Science and Technology Computation Physics Laboratory, Institute of Applied Physics and Computational Mathematics, Beijing 100088, China;,   Data Center for High Energy Density Physics, Institute of Applied Physics and Computational Mathematics, Beijing 100088, China
Published: December 2020

Solving numerically the time-dependent Schrödinger equation in three-dimensional momentum space, we have investigated the energy spectroscopy and two-dimensional momentum angular distribution near the ionization threshold of the photoelectron generated from excited atom under the action of high-frequency laser pulse. The results show that the ionized process is mainly the single-photon ionization in this energy range. The principal quantum number of the initial state can be determined by the position of the first peak in photoelectron spectrum; its angular quantum number of the initial state can be determined by the angular distribution of the two-dimensional momentum of the photoelectron. This law does not change with the variation of the intensity and pulse duration of the incident laser pulse within a relatively broad range of these parameters. In principle, we can utilize these spectra to identify the initial state of the atoms. In addition, the photoelectron momentum spectrum of superposition state is investigated for different relative phase of the state.
Iterative method for multimode waveguide design
Authors: Wang Qiang  , Zhou Hai-Jing  , Yang Chun  , Li Biao  , He Xiao-Yang  ,   Institute of Engineering electrics, CAEP, Mianyang 621900, China;,   Institute of Applied Physics and Computational Mathematics, Beijing 100094, China;,   Department of Engineering Physics, Tsinghua University, Beijing 100084, China
Published: December 2020

Coupled mode theory is an effective tool for analysis and synthesis of overmoded waveguides, but the inverse problem has not been solved yet. This paper completed the iterative procedure to solve the inverse problem. The new method can design automatically and fast various mode converters, mode transducers and horn antennas with special radial pattern. Compared with conventional methods, the structure design using the new method has more advantages in electromagnetic and structural properties. Two design examples are given: dual band TM01-TE11 mode converter and smooth-wall feed horn antenna. The two working frequencies of the dual band TM01-TE11 mode converter are 8.75 GHz and 10.3 GHz, and the radius is 16 mm. The converter efficiencies exceed 99% at the two working frequencies. The smooth-wall feed horn antenna converts the TE11 mode to Gaussian beam effectively. Simulation results agree well with the theoretical predictions.
Effect of co-implantation of nitrogen and fluorine on the fixed positive charge density of the buried oxide layer in SIMOX SOI materials
Authors: Zhang Bai-Qiang  , Zheng Zhong-Shan  , Yu Fang  , Ning Jin  , Tang Hai-Ma  , Yang Zhi-An  ,   School of Physics and Technology, University of Jinan, Jinan 250022, China;,   Institute of Microelectronics, Chinese Academy of Sciences, Beijing 100029, China;,   Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
Published: December 2020

Nitrogen ions implanted into the buried oxide layer can increase the total dose radiation hardness of silicon on insulator (SOI) materials. However, the obvious increase in positive charge density in the buried layer with high dose of nitrogen implantation leads to a negative effect on the technology of nitrogen implantation into buried oxide. In order to suppress the increase in positive charge density in the nitrogen-implanted buried layer, co-implantation of nitrogen and fluorine is used to implant fluorine into the nitrogen-implanted buried layer. High-frequency voltage-capacitance (C-V) technique is used to characterize the positive charge density in the buried layer. Results show that, in most cases, using the co-implantation of nitrogen and fluorine can significantly reduce the positive charge density in the nitrogen-implanted buried layer. At the same time, it is also found that further increase of the positive charge density induced by fluorine implantation in the nitrogen-implanted buried layer can occur in particular cases. It is proposed that the decrease in the positive charge density in the fluorine and nitrogen-implanted buried layer is due to the introduction of electron traps into the buried layer through fluorine implantation.
Resonant frequency temperature stability of CaTiO3 based microwave dielectric ceramics
Authors: Shen Jie  , Zhou Jing  , Shi Guo-Qiang  , Yang Wen-Cai  , Liu Han-Xing  , Chen Wen  ,   State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China;,   Key Laboratory of Advanced Technology for Specially Functional Materials, Wuhan University of Technology, Wuhan 430070, China;,   School of Materials Science and Engineering, Wuhan University of Technology, Wuhan 430070, China
Published: December 2020

The determinants of resonant frequency temperature coefficient (τf) have been analyzed by the approximate treatment of Clausius-Mossotti equation. It is suggested that the value of τf can be adjusted by changing the contribution proportion of ionic polarization or electronic polarization for the dielectric constant. Results of electronic structure calculation and tolerance factor analysis show that B-site substitution of CaTiO3 with (Zn1/3Nb2/3)4+ could turn the value of τf from positive to negative, by enhancing the covalency in the BO6 octahedron and improving the contribution proportion of electronic polarization. Ca[(Zn1/3Nb2/3)xTi(1-x)]O3 dielectric ceramics were prepared by solid-state reaction method with niobate as precursor. Results of structure analysis and property measurement conform to the theoretical analysis. The Ca[(Zn1/3Nb2/3)0.7Ti0.3]O3 dielectric ceramic with near-zero τf was obtained.
MCG source reconstruction based on greedy sparse method
Authors: Bing Lu  , Wang Wei-Yuan  , Wang Yong-Liang  , Jiang Shi-Qin  ,   School of Electronics and Information Engineering, Tongji University, Shanghai 201804, China;,   Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China
Published: December 2020

Current source reconstruction, i.e., reconstructing current dipole distribution through measured array signals of cardiac magnetic field on body surface, is a method for non-invasively study on the heart electrical activity. In this paper, the relationship between measured magnetic signals and current dipole distribution is described by a linear equation, and a sparse solution of current source reconstruction is achieved using a fast greedy method. This method can significantly decrease the computational complexity of or- thogonal matching pursuit (OMP) algorithm by means of approximating orthogonalisation and improving the selection vector strategy per iteration. Thereby, the sources with large dipole strength can be fast searched out with high accuracy. A set of magnetocardiogram (MCG) data of normal subject is used to demonstrate the effectiveness of this method that the trajectory of reconstructed dominant sources, whose strengths are more than 65%, is almost consistent with conduction process in depolarization and repolarization. The average goodness of fit (GOFs) of measured MCG and the magnetic field map generated by the reconstructed current sources during QRS complex and ST-T segment are 99.36% and 99.78%, respectively.