bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical study of long-range interaction between two beams in (1+2)-dimensional thermal nonlocal media
Authors: Lu Da-Quan  , Qi Ling-Min  , Yang Zhen-Jun  , Zhang Chao  , Hu Wei  ,   Laboratory of Nanophotonic Functional Materials and Devices, School of Information and Optoelectronic Science and Engineering, South China Normal University, Guangzhou 510631, China
Published: December 2020

According to the nonlinear Schrödinger equation and Poisson equation of thermal diffusion, we investigate the interaction of double beams in (1+2)-dimension thermal nonlocal medium, using the slip-step Fourier algorithm and multi-grid method. The results show that the two beams intertwine with each other during propagation. If the power and the tilt parameter are appropriate, the projections of the trajectories of the beams in (X, Y) plane are approximately circle, even if the incident distance between the beams is changed. Because of the strongly nonlocal property of thermal medium, the influences of boundaries and initial transverse momentum can be felt when beams are far from the boundaries; there will be an oscillatory propagation when the mass center of the input field deviates from sample center or the initial transverse momentum is unequal to zero.
Influence of monitoring point wavelength on axial strain sensitivity of high-birefringence fiber loop mirror
Authors: Jiang Ying  , Liang Da-Kai  , Zeng Jie  , Ni Xiao-Yu  ,   State Key Laboratory of Mechanics and Control of Mechanical Structures, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 China;,   School of Mechanical and Electronic Engineering, Nanjing Forestry University, Nanjing 210037, China
Published: December 2020

The influence of the monitoring point wavelength on the axial strain sensitivity of high-birefringence fiber loop mirror is investigated. The theoretical expression for the axial strain sensitivity of high-birefringence fiber loop mirror is developed. The results show that the sensitivity increases with the wavelength of the monitoring point increasing when the high-birefringence fiber material is certain, that the sensitivity is constant and the wavelength shift is linear versus strain for the certain monitoring point. The axial strain sensitivities of the different wave peaks are monitored in experiment. The experimental results of data fitting are in good agreement with the theoretical ones. The research results help to improve the strain sensitivity, the temperature sensitivity, etc. of high-birefringence fiber loop mirror.
The measure of environmental sensitivity in detection performance degradation
Authors: Liu Zong-Wei  , Sun Chao  , Du Jin-Yan  ,   Institute of Acoustic Engineering, Northwestern Polytechnical University, Xi’an 710072, China
Published: December 2020

Existing detection methods have mismatch problem when applyed to the real uncertain ocean, which will lead to the detection performance degradation. However, there has been little work on defining the practical quantitative measures of environmental sensitivity. In this article we define a measure of environmental sensitivity for target detection performance loss in an uncertain ocean for realistic uncertainties in various environmental parameters (water-column sound speed profile and seabed geoacoustic properties). The Monte Carlo approach is used to transfer the environment uncertainty through the forward problem and quantify the resulting variability in the detection performance loss. The computer simulation is based on the Malta Plateau, a well-studied shallow-water region of the Mediterranean Sea. The simulation result shows that 1) the sensitivity is range and depth dependent and in the sound channel the sensitivity is much smaller than in other regions of the ocean; 2) the sound speed profile and the upper seabed layer are most sensitive parameters for the detection performance loss; 3) the sensitivity is frequency dependent. The seabed layer properties such as sediment thickness, density and attenuation coefficient have less influence on the detection as the frequency increases.
Hydrodynamic characters of a near-wall circular cylinder oscillating in cross flow direction in steady current
Authors: Chen Ying  , Fu Shi-Xiao  , Xu Yu-Wang  , Zhou Qing  , Fan Di-Xia  ,   China State Key Laboratory of Ocean Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
Published: December 2020

Hydrodynamic characteristics of a near-wall circular cylinder oscillating in direction perpendicular to steady current are experimentally investigated at a Reynolds number of 2× 105. Forces in both in-line and cross-flow are measured by the three-dimensional force transducers. The effects of gap ratio, oscillating frequency and amplitude on the hydrodynamic charactersistic of the cylinder are studied. Experimental results indicate that 1) mean drag reduces rapidly when the gap ratio decreases from 0.7 to 0.3; 2) for an oscillating cylinder, the critical gap ratio of vortex shedding suppression is smaller than that for a still cylinder; 3) the existence of near-wall influences the energy transfer between the structure and fluid significantly, which means that hydrodynamic coefficient based on free-wall cylinder may not be suitble for predicting vortex induced vibration of pipelines; 4) for an oscillating cylinder, added mass is not a constant except for in a certain range of oscillating frequency, and the absolute value increases with the decrease of gap ratio in low frequency range; 5) mean drag coefficient, oscillating drag coefficient and oscillating lift coefficient all increase with oscillating amplitude increasing.
A numerical analysis of drop impact on solid surfaces by using smoothed particle hydrodynamics method
Authors: Su Tie-Xiong  , Ma Li-Qiang  , Liu Mou-Bin  , Chang Jian-Zhong  ,   School of Mechatronice Engineering, North University of China, Taiyuan 030051, China;,   Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China
Published: December 2020

In this paper, we present a numerical simulation of a single liquid drop impacting onto solid surface with smoothed particle hydrodynamics (SPH). SPH is a Lagrangian, meshfree particle method, and it is attractive in dealing with free surfaces, moving interfaces and deformable boundaries. The SPH model includes an improved approximation scheme with corrections to kernel gradient and density to improve computational accuracy. Riemann solver is adopted to solve equations of fluid motion. An new inter-particle interaction force is used for modeling the surface tension effects, and the modified SPH method is used to investigate liquid drop impacting onto solid surfaces. It is demonstrated that the inter-particle interaction force can effectively simulate the effect of surface tension. It can well describe the dynamic process of morphology evolution and the pressure field evolution with accurate and stable results. The spread factor increases with the increase of the initial Weber number. The numerical results are in good agreement with the theoretical and experimental results in the literature.
Experimental investigations on the propagation characteristics of internal solitary waves over a gentle slope
Authors: Du Hui  , Wei Gang  , Zhang Yuan-Ming  , Xu Xiao-Hui  ,   College of Meteorology and Oceanography, PLA University of Science and Technology, Nanjing 211101, China
Published: December 2020

In a stratified fluid tank, experiments on the propagating, shoaling and breaking of the internal solitary waves over a gentle slope similar to the topography in the northeast of the South China Sea are conducted. The qualitative analysis on the evolving characteristics of the internal solitary waves is accomplished by use of the dye-tracing technique, and their quantitative measurement is carried out by using the multi-channel conductivity-probe arrays. It is shown that due to the shoaling effect the internal solitary waves with large amplitude are restrained, but the waves with small amplitude are magnified. The shoaling effect will also lead to the decrease of the propagation velocity of the internal solitary waves. Further, the shoaling effect will bring about strong shear flow instability, and then makes the internal solitary wave broken. The breaking wave will result in the fission from one large amplitude wave into several small amplitude waves with the same polarity. By means of the Mile's stability theory, the instable happening-location of the internal solitary wave over the gentle slope can be described through the Richardson number. The experimental results accord well with the theoretical analyses.
Strain control of the leakage current of the ferroelectric thin films
Authors: Wen Juan-Hui  , Yang Qiong  , Cao Jue-Xian  , Zhou Yi-Chun  ,   Department of Physics and Institute for Nanophysics and Rare-earth Luminescence, Xiangtan University, Xiangtan 411105, China
Published: December 2020

Combining nonequilibrium Green's functions and first-principles quantum transport calculations in density-functional theory, we investigate the effect of biaxial strain on the leakage current of BaTiO3 ferroelectric thin film. The results show that the compressive strain can effectively reduce the leakage current of ferroelectric thin film. Especially when the compressive strain is 4%, the leakage current will be reduced by nearly 10 times that of strain-free case. By calculating the transmission coefficient and the density of states, we find that the transmission probability of ferroelectric tunnel junction with compressive strain is smaller than that with tensile strain. Moreover, we find that the valence band shifts toward the lower energy zone while the conduction band moves toward the high energy zone, which leads to the enlarged energy band gap, thereby reducing the leakage current. Our study suggestes a suitable way to reduce the ferroelectric thin film leakage current and improve the performance of ferroelectric thin film and its relevant ferroelectric memory.
Positioning performance evaluation of magnetic contour matching under different accuracy of sensor
Authors: Zhao Long  , Yan Ting-Jun  ,   Science and Technology on Aircraft Control Laboratory, Beihang University, Beijing 100191, China;,   Digital Navigation Center, Beihang University, Beijing 100191, China
Published: December 2020

The accuracy of geomagnetic reference map, geomagnetic sensor, and inertial navigation system is the key factor which affects the reliability of magnetic contour matching (MAGCOM) system. In order to improve the reliability of MAGCOM, the influence of the sensor's accuracy on the matching success rate has been studied. For different geomagnetic reference maps, the factors and their physical mechanism affecting matching success rate have been analyzed, the factors are geomagnetic sensor error, velocity error, and heading angle error. The error range of sensors was determined by the simulation computing which was based on a practical system and a simulation experimentation was implemented by using the geomagnetic reference map. The simulation results show that MAGCOM can allow the velocity error 0.14 m/s, the heading angle error 0.6 and the standard deviation of geomagnetic sensor noise 11 nT, when the matching success rate is 90%.
The influence of the excition recombination zone on the organic magnetic-field effect
Authors: Li Dong-Mei  , Wang Guan-Yong  , Zhang Qiao-Ming  , You Yin-Tao  , Xiong Zu-Hong  ,   School of Physical Science and Technology, MOE Key Laboratory on Luminescence and Real-Time Analysis, Southwest University, Chongqing 400715, China;,   Surface Physics Laboratory (National Key Laboratory), Fudan University, Shanghai 200433, China
Published: December 2020

In this work we explore the influence of the exciton recombination zone (RZ) on magnetic-field effect in tris-(8-hydroxyquinolinato) aluminum (Alq3) based organic light-emitting diodes by changing the thickness of Alq3. The magneto-electroluminescence and magneto-conductance (MC) in these devices are investigated at various temperatures and bias voltages. It is found that the sign of MC changes from positive to negative, and then back to positive with the reduction of the thickness of Alq3 at 50 K. The phenomenon observed is ascribed to the change of the exciton density in the exciton RZ. Based on the mechanisms including the hyperfine mixing, the triplet-charge interaction and interfacial dissociation or quenching of excitons, the observed results are explained qualitatively.
Analysis of gas isolation by prominent O-ring on the mold in compressional gas cushion press nanoimprint lithography
Authors: Li Tian-Hao  , Zheng Guo-Heng  , Liu Chao-Ran  , Xia Wei-Wei  , Li Dong-Xue  , Duan Zhi-Yong  ,   Physical Engineering College of Zhengzhou University, Zhengzhou 450001, China
Published: December 2020

Nanoimprint lithography has the advantages of low-cost, high-throughput, ultrahigh resolution, which could make it one of the next generation lithography technologies. However, the bubble-defect is always a problem which may damage the duplicate patterns, so it is an urgent issue to propose effective solutions. A novel methods, which is suitable for compressional gas cushion press nanoimprint lithography in gas atmosphere and could prevent gas from entering the gap between mold and substrate, is presented here. The annular plate capillary gap formed between the smooth substrate and the prominent O-ring processed by etching the original mold would be filled with the fluid medium. The capillary liquid bridge between the O-ring and substrate produces a closed cavity. The stiction induced by adhesion force and the capillary force induced by air-liquid surface tension could resist the compressed gas and avoid the bubble defect. The effective widths of the prominent O-ring, which are different for various fluids with different surface properties, are deduced by theory analysis. The analysis results provide theoretical basis for the preparation of the mold.
First-principles studies of the structural and thermodynamic properties of TiAl3 under high pressure
Authors: Wang Hai-Yan  , Li Chang-Yun  , Gao Jie  , Hu Qian-Ku  , Mi Guo-Fa  ,   School of Materials Science and Engineering, Henan Polytechnic University, Jiaozuo 454000, China
Published: December 2020

In this paper, the structural properties of TiAl3 intermetallics are investigated by the plane-wave pseudopotential density functional theory method. The calculated results are consistent with experimental and other theoretical ones. Through the quasi-harmonic Debye model we calculate the thermodynamic properties and obtain the dependences of relative volume V/V0 on pressure P and temperture T, as well as the thermal expansion and specific heat coefficients under different temperatures and pressures. For the calculated results of TiAl, we find that the increase rate of thermal expansion coefficient of TiAl under the increase of temperature is higher than that of TiAl3, and further, the effect of temperature weakens with the increase of pressure. The specific heat of TiAl3 is nearly twice that of TiAl.
Coupling analysis of multivariate bioelectricity signal based symbolic partial mutual information
Authors: Zhang Mei  , Cui Chao  , Ma Qian-Li  , Gan Zong-Liang  , Wang Jun  ,   Image Processing and Image Communications Key Laboratory, Nanjing University of Posts and Telecommunication, Nanjing 210003, China;,   Mechanical Engineering College, Zhengzhou University, Zhengzhou 450001, China
Published: December 2020

Symbolic partial mutual information is proposed in this paper, which is based on partial mutual information. This algorithm can be used to analyse the coupling between multivariate time series. We use this method to treat and analyse the sleeping multivariate bioelectricity signal (MBS) and wake one, it turns out that the coupling of wake MBS is obviously bigger than that of sleeping MBS. Finally hypothesis testing is done to prove that this method works and the average energy dissipation can be used as a parameter to detect nonequilibrium.
Summer precipitation response to the length of the preceding winter over yangtze-huaihe river valley
Authors: Su Tao  , Zhang Shi-Xuan  , Zhi Rong  , Chen Li-Juan  ,   College of Atmospheric Sciences, Lanzhou University, Lanzhou 730000, China;,   National Climate Center, Laboratory for Climate Studies of China Meteorological Administration, Beijing 100081, China
Published: December 2020

By using NCEP/NCAR reanalysis datasets, the length of preceding winter (LPW) in the Yangtze-Huaihe River valley (YHRV) from 1961 to 2011 is derived. We investigate the variation of LPW and the relationship between LPW and following summer precipitation, and the results indicate that LPW clearly displays interannual and decadal changes in the period of 1961-2011. The variation of LPW is closely related to temperature, pressure and meridional wind speed, statistical analysis indicates that a longer LPW corresponds to a lower temperature, a higher pressure and a stronger meridional wind, which shows that temperature, pressure, meridional wind are probably the key factors of adjusting the LPW. These characteristics also vary from region to region. There is significantly positive correlation between the summer precipitation and LPW. The statistical analysis also indicates that the longer (shorter) the LPW, the more (less) the summer precipitation in YHRV is. The comprehensive analysis of the circulation field indicates that when LPW is significantly longer than climatic status, a blocking situation is formed easily in the region of Ural Mountains and the Sea of Okhotsk in the summer, which will affect the summer rainfall in YHRV. By using singular value decomposition method, it is found that the relationship between summer precipitation and LPW is also very significant.
Pulsar signal denoising method based on empirical mode decomposition mode cell proportion shrinking
Authors: Wang Wen-Bo  , Zhang Xiao-Dong  , Wang Xiang-Li  ,   School of Information and Computational Science, Wuhan University of Science and Technology, Wuhan 430065, China;,   State Key Laboratory of Remote Sensing Science, Beijing 100101, China;,   State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography, State Oceanic Administration, Hangzhou 310012, China;,   School of Computer Science and Technology, Wuhan University of Technology, Wuhan 430063, China
Published: December 2020

In order to improve the denoising quality of the pulsar signal, an empirical mode decomposing method (EMD) of pulsar signal denoising based on mode cell proportion shrinking is proposed. Firstly, the pulsar signal is decomposed into a series of intrinsic mode functions (IMF), and the part between the two adjacent zero-crossing within IMF is defined as a mode cell. Then, the optimal proportional shrinking factor is constructed by treating mode cell as the basic unit of analysis. Finally, the all mode cells within IMF are denoised by proportion shrinking, and the mode cell proportion shrinking denoising model is established. The experimental results show that compared with the two EMD denoising algorithms based on coefficient threshold and mode cell threshold, the proposed method can more effectively remove the pulsar signal noise, with better preserving the useful detail information in the original signal.
Full-vectorial finite-difference analysis of modes in waveguide with arbitrary shape
Authors: Qiao Hai-Liang  , Wang Yue  , Chen Zai-Gao  , Zhang Dian-Hui  ,   Northwest Institute of Nuclear Technology, Xi’an 710024, China
Published: December 2020

The full-vectorial finite-difference method has been improved for solving mode loading problem on irregular ports, and the boundary conditions are derived. The new mode solver reduces the demand for computing resources: it can solve waveguide mode with arbitrary shape. The mode characteristics of waveguide with different shape are calculated; the results are compared to analytical solutions and those obtained from commercial software, they agree well with one another.
Improving the maximum transmission distance of coutinuous variable no-switching QKD protocol
Authors: Xu Bing-Jie  , Tang Chun-Ming  , Chen Hui  , Zhang Wen-Zheng  , Zhu Fu-Chen  ,   Science and Technology on Communication Security Laboratory, Chengdu 610041, China
Published: December 2020

Developing quantum key distribution (QKD) protocols that can resist losses and noises is of great importance in practice. We show that the maximum transmission distance and tolerable excess noise of the no-switching CV-QKD protocol can be dramatically increased by using a noiseless linear amplifier (NLA). It is proved that an NLA with a gain g can increase the maximum transmission distance by 20 log10g/α km, where α=0.2 dB/km is the loss coefficient of the fiber channel.
Stochastic resonance of cascaded bistable duffing system
Authors: Lai Zhi-Hui  , Leng Yong-Gang  , Fan Sheng-Bo  ,   School of Mechanical Engineering, Tianjin University, Tianjin 300072, China;,   Key Laboratory of Mechanism Theory and Equipment Design of Ministry of Education, Tianjin University, Tianjin 300072, China;,   Tianjin Key Laboratory of Nonlinear Dynamics and Chaos Control, Tianjin 300072, China
Published: December 2020

The stochastic resonance of cascaded bistable Duffing system (CBDS) has been studied in this paper. We have shown that with the appropriate adjustment of the parameters of the CBDS, such as the scale transformation coefficient, the damping ratio and the number of cascaded systems, the CBDS can not only achieve large or small parameter stochastic resonance, but also optimize the stochastic resonance result of a single bistable Duffing system (SBDS). That is, with the parameter adjustment, the stochastic resonance effect of the CBDS is much better than that of the SBDS. Furthermore, the CBDS has excellent filtering and smoothing characters for a square wave signal, which can be applied to the recovery of the square wave signal masked by heavy noise.
Purity analysis of helium using quartz-enhanced photoacoustic spectroscopy with two non-resonant micro-tubes
Authors: Wu Hong-Peng  , Dong Lei  , Zheng Hua-Dan  , Liu Yan-Yan  , Ma Wei-Guang  , Zhang Lei  , Wang Wu-Yi  , Zhu Qing-Ke  , Yin Wang-Bao  , Jia Suo-Tang  ,   State Key Laboratory of Quantum Optics and Quantum Optics Devices, Lab for Laser Spectroscopy, Shanxi University, Taiyuan 030006, China;,   Shanxi Institute of Metrology, Taiyuan 030006, China
Published: December 2020

A trace gas sensor, based on quartz-enhanced photoacoustic spectroscopy (QEPAS) with two non-resonant micro-tubes, was designed to detect the ammonia concentration in impure helium. Unlike the traditional micro-resonator, the non-resonant micro-tubes are used to confine the sound wave, but do not exhibit a well-defined resonant behavior. Such a design makes the dimension of the spectrophone much smaller than the micro-resonant configuration, which facilitates the optical alignment. Signal and noise, that were dependent on gas pressure, were also investigated to optimize sensor performance. With the optimal sensor parameters and the optimal gas pressure, the detection sensitivity was found to be 463 ppb (1 , 1 s averaging time), which corresponds to the normalized absorption sensitivity of 4.310-9cm-1W/Hz.
The ground state properties and excitation properties for the SnSe molecule under different external electric fields
Authors: Wang Fan-Hou  , Huang Duo-Hui  , Yang Jun-Sheng  ,   Yibin University Key Laboratory of Computational Physics, Yibin University, Yibin 644000, China
Published: December 2020

Effects of electric field ranging from -0.04 to 0.04 a.u., on the equilibrium structure, mulliken atomic charges, the highest occupied molecular orbital(HOMO) energy level, the lowest unoccupied molecular orbital(LUMO) energy level, energy gap, fermi energy, harmonic frequency and infrared intensities of SnSe ground state molecule are investigated by employing density functional (B3LYP) method with SDB-cc-pVTZ for Sn atom and 6-311++G** basis sets for Se atom. The magnitude and direction of the external electric field have significant effects on these characteristics of SnSe molecule. The results show that the bond length is proved to be first decreasing, and then increasing with the increase of the external field, and the minimum value is 0.2317 nm when the field strength is equal to 0.03 a.u.; electric dipole moment is found to increase linearly with the increase of external field, but the HOMO energy EH, LUMO energy EL, energy gap Eg and fermi energy EF are proved to decrease with the increase of external field. The total energy and harmonic frequency are found to first increase, and then decrease, but the infrared intensities are proved to first decrease, and then increase. The wavelengths from ground state to the first ten excited states are found to increase, but the excited energies are decreasing with the increase of the external field. Meanwhile, the sequence of excited states for SnSe molecule can be changed, and some prohibited transition can be allowed under an external field.
Effects of external electric field on the excitation properties of anthracene molecule
Authors: Xu Guo-Liang  , Yuan Wei  , Geng Zhen-Duo  , Liu Pei  , Zhang Lin  , Zhang Xian-Zhou  , Liu Yu-Fang  ,   College of Physics & Electronic Engineering, Henan Normal University, Xinxiang 453007, China
Published: December 2020

The theoretical investigations on the molecular energy levels, energy gaps, and the singlet-singlet electronic excitation properties (such as absorption spectra, excited energy, oscillator strengths) of the anthracene molecule in different external electric field were carried out by employing density functional theory (DFT) and time-dependent density functional theory (TDDFT) method with 6-311G(d, p) basis set. The stable molecular structure in ground state was optimized by DFT. The calculated results show that the absorption bands of anthracene molecule concentrate in ultraviolet region without external electric field, the absorption peak of which corresponds to the S0→S5 transitions with an excitation wavelength of 234.5 nm. The calculated absorption spectra agree well with the experimental data. Moreover, it is noticeable that the effects of the external electric field on optical properties cannot be neglected. The ultraviolet absorption spectra of anthracene molecule show a red shift into the blue-light region with the increases of electric field intensity. At the same time, the energy gaps between LUMO and HOMO for the anthracene molecule decrease with the increase of external electric field intensity. It can be shown that the anthracene molecule is promising as a useful blue-light emitting material through modulating by an electric field.
The effect of atomic potential on the above threshold ionization
Authors: Tian Yuan-Ye  , Guo Fu-Ming  , Yang Yu-Jun  ,   Institute of Atomic and Molecular Physics, Jilin University, Changchun 130012, China
Published: December 2020

We investigate theoretically the influence of the long-range and short-range potentials on the plateau structure of the above threshold ionization. In a considerable range of laser parameter, the above threshold ionization spectra of the atoms in the long-range potential always exhibit a clear double-plateau structure; as for the atoms with a short-range potential, the boundary of the double-plateau in photoelectron spectra is no longer clear, and with the decrease of laser intensity, it transits from the double-plateau to the single-plateau gradually. The numerical simulation based on classical analysis and quantum mechanics illustrates that in different model potentials, the distinction of ionization rates as well as the difference of the electronic elastic rescattering cross-sections results in the difference of plateau structures. In addition, the influence of intensity distribution of laser pulse on the phenomenon is discussed.
Design and experiments of low-frequency broadband metamaterial absorber based on lumped elements
Authors: Wang Ying  , Cheng Yong-Zhi  , Nie Yan  , Gong Rong-Zhou  ,   Department of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, China
Published: December 2020

A structure of matematerial absorber constructed based on lumped elements is proposed, analyzed theoretically and verified experimentally. The simulated results indicate that the absorption of the proposed absorber is over 95% in the frequency range of 2.5 to 4.46 GHz, and the FWHM is 70.4%. The designed structure has a better impedance matching characteristic to the free space in a wider frequency range when loaded with lumped elements by scattering parameter retrieval calculation. It also can be found that the large loss occurs in lumped resistance, which contributes much to the low-frequency broadband absorption properties obtained by simulating the energy loss distribution of the dielectric surface. Results measured by means of the free space method agree well with the simulation. Further measured results also show that the thickness of FR4 substrate obviously has controllable effects on absorption properties of the absorber, the absorption wide band will move to lower frequency with the increase of thickness, and the optimal thickness for the structure of certain parameters also can be obtained.
Numerical simulation of different ratios of oscillator to amplifier of chemical laser with MOPA configuration
Authors: Guo Jian-Zeng  , Liu Tie-Gen  , Niu Zhi-Feng  , Ren Xiao-Ming  ,   College of Precision Instrument and Opto-electronics Engineering, Tianjin University, Tianjin 300072, China;,   The 718th Research Institute of CSIC, Handan 056027, China
Published: December 2020

Master oscillator power-amplifier (MOPA) configuration was widely used in high-power laser system. In order to find the optimal ratio of oscillator to amplifier, influences of this ratio on the near-field intensity distribution and the output power were studied. Fast Fourier transform method was used to calculate the near-field intensity distribution and the powers at the ratios of 1:4, 1:1 and 2:1. The simulation results indicated that when the total volume of the gain is constant, the output power of the oscillator increases with the ratio. The results also showed that the diffraction influence increases with the length of the amplifier. It was noted that the ultimate output power of the laser system was affected by the ratio of oscillator to amplifier intensity, when the laser was run at the same gain distribution, saturable intensity, amplification of the unstable oscillator, size of the whole laser and various losses of the cavity.
Simulation of N2 microhollow cathode discharge and cathode sputtering by using a PIC/MC model
Authors: Zhang Lian-Zhu  , Meng Xiu-Lan  , Zhang Su  , Gao Shu-Xia  , Zhao Guo-Ming  ,   College of Physics Science and Information Engineering, Hebei Normal University, Shijiazhuang 050024, China
Published: December 2020

The nitrogen microhollow cathode discharge and Ti cathode sputtering, bombarded by ions (N2+, N+), have been studied using a two-dimensional PIC/MCC model. The behavior of ions (N2+, N+) and sputtered atom (Ti), and the thermalization process of the sputtered atoms in a nitrogen microhollow cathode discharge are simulated. The results show that hollow cathode effect is due to electron oscillations in the overlapping negative glow under our simulation condition. The densities of ions (N2+, N+) in the microhollow cathode discharge are two orders in magnitude greater than that in the conventional hollow cathode discharge; but the distributions and sizes of the mean energy of the ions (N2+, N+) are almost the same. The density of N2+ is fivefold as much as that of N+ in the microdischarge space; however, the maximum of mean energy of the latter is twice larger than the former. For various parameters (P, T, V), the densities of ions(N2+, N+) bombarding the cathode internal surface are almost uniformly distributed, and their mean energy are almost the same. When these atoms are 0.15 mm away from the cathode. The sputtered atoms are almost thermalized completely.
Experimental study on the thrust and the ratio of thrust to power of multi-points/grid ionic wind exciter
Authors: Wang Wei  , Yang Lan-Jun  , Gao Jie  , Liu Shuai  ,   Department of Electrical Engineering, State Key Laboratory of Electrical Insulation and Power Equipment, Xi’an Jiaotong University, Xi’an 710049, China
Published: December 2020

The thrust of ionic wind exciters in 19 points-grid and 31 points-grid electrodes configurations was measured in this paper by means of air suspension test platform without friction. Meanwhile, a control method was also provided for multipoint-grid ionic wind exciter. And then the study was done on the factors, e.g. the gap of point-grid electrodes, the spacing between points, the curvature radius of the point, and the voltage, current of corona discharge, all of which may affect the thrust character; so some methods for getting high thrust at low power were also proposed in order to improve the thrust and the thrust per unit power at the same time.
Tunable capability of dye-doped cholesteric liquid crystal lasers
Authors: Liu Yong-Jun  , Wang Fei-Ru  , Sun Wei-Min  , Liu Xiao-Qi  , Zhang Ling-Li  ,   College of Science, Harbin Engineering University, Harbin 150001, China;,   College of Automation, Harbin Engineering University, Harbin 150001, China;,   College of Science, Harbin Institute of Technology University, Harbin 150001, China
Published: December 2020

Based on the fact that helical pitch and average refractive index of a cholesteric liquid crystal is electric-tunable and temperature-tunable, we have designed dye-doped cholesteric liquid crystal (CLC) lasers. First, the effects of the concentration of chiral and the temperature on helical pitch are investigated. Next, we gain the relationship of tunable laser with temperature and electric field. When the temperature is changed from 23 to 35℃, the wavelength shift of the lasing peak vasies from 618.90 to 594.76 nm, nearly 24.14 nm in total; when the electric field is changed from 0 to 9 V, the wavelength shift of the lasing peak ehanges from 617.40 to 608.11 nm, nearly 9.29 nm in total.
Optical SHG properties of GaAs nanowires irradiated with multi-wavelength femto-second laser pulses
Authors: Zhang Xiao-Qing  , He Hao  , Hu Ming-Lie  , Yan Xin  , Zhang Xia  , Ren Xiao-Min  , Wang Qing-Yue  ,   Ultrafast Laser Laboratory, School of Precision Instruments & Optoelectronics Engineering, Tianjin University; Key Laboratory of Optoelectronic Information Technical Science, Chinese Ministry of Education, Tianjin 300072, China;,   Key Laboratory of Information Photonics and Optical Communications, Ministry of Education, Beijing University of Posts and Telecommunications, Beijing 100876, China
Published: December 2020

The nonlinear optical properties of semiconductor nanowires are of vital importance in the researches of nano-optics and fabrication of nano-scale optoelectronic components. GaAs is a direct bandgap semiconductor material of wide bandgap, high electron mobility, large χ(2), high laser damage threshold and stable chemical properties, all of which make it a potential nonlinear optical material. In this report, based on the finite element method (FEM), we investigated the optical response and local field enhancement of GaAs nanowires perpendicular to the GaAs substrate surface. Under the radiation of femto-second laser pulses at different wavelengths, efficient second harmonic generation (SHG) signal was acquired from the nanowires. Furthermore, noise-free broadband SHG signal was also detected to be excitated by super-continuous femto-second pulses (1000-1300 nm). The high-efficiency SHG process could be attribated mainly to the local field enhancement effect of the nanowires. Our investigation is the first, as far as we know, demonstrate the SHG properties of GaAs nanowires, and the results suggest that GaAs nanowires are promising in the potential applications in nano-scale optical devices, integrated nanophotonic circuits, from which related nano-optics researches can benefit.
Effects of total ionizing dose on narrow-channel SOI NMOSFETs
Authors: Ning Bing-Xu  , Hu Zhi-Yuan  , Zhang Zheng-Xuan  , Bi Da-Wei  , Huang Hui-Xiang  , Dai Ruo-Fan  , Zhang Yan-Wei  , Zou Shi-Chang  ,   The State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, the Chinese Academy of Sciences, Shanghai 200050, China;,   Graduate University of the Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

The effects of total ionizing dose on narrow-channel N-type metal-oxide-semiconductor field-effect-transistors (NMOSFETs) in a 130 nm partially depleted silicon-on-insulator (SOI) technology are presented. The charge conservation principle is utilized to analyze the radiation-induced narrow-channel effect (RINCE). In addition, it is found for the first time, as for as we know that for the narrow-channel NMOSFETs operated in the linear region, the radiation-induced positive charges trapped in the shallow trench isolation can increase the probability of electron-electron collisions and surface roughness scattering, resulting in the degradation of the carrier mobility and transconductance of the main transistor. Finally, the RINCE as well as the degradation of the carrier mobility has been verified by our three-dimensional device simulation; and good agreement between the simulation and experimental results is obtained.
Structures, mechanical and tribological properties of (Zr,V)N composite films
Authors: Yu Li-Hua  , Ma Bing-Yang  , Cao Jun  , Xu Jun-Hua  ,   Materials Science and Engineering, Jiang Su University of Science and Technology, Zhen Jiang 212003, Cnina
Published: December 2020

(Zr,V)N thin films with different V contents were deposited by reactive unbalanced magnetron sputtering. Their chemical composition, microstructure, mechanical and tribological properties were investigated by EDS, XRD, XPS, nanoindentation and tribometer. The results indicated that the fcc crystal structure of ZrN has not been changed by adding vanadium added, but the preferential orientation of films change from (200) to (111). As the V contents increased, the hardness of (Zr,V)N thin films decreased slowly after increased slightly, and decreased rapidly when V contents increased over 25.8 at.%. With increasing V contents, the coefficient of friction of (Zr,V)N thin films decreased slightly. The V2O3 was firstly found in the film of (Zr,V)N at 300 ℃ and when the temperature was increased over 500 ℃, the presence of V2O5 was found. Moreover, with the increase of the temperature the content of V2O5 increased, and the coefficient of friction of films decreased with the formation of V2O5.
Synthesis and electrical property of oxide ionic conductor La1.9Y0.1Mo2O9 fine grain ceramic
Authors: Zhang De-Ming  , Zhuang Zhong  , Wang Xian-Ping  , Fang Qian-Feng  ,   The Key Lab of Photonic Devices and Materials, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China;,   The Key Lab of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, China
Published: December 2020

A series of La1.9Y0.1Mo2O9 bulk samples of different grain sizes were made by microwave sintering the nanocrystalline powders prepared by sol-gel methods. Phases, microstructure, grain size of the powders and bulk samples were examined by using X-ray diffraction (XRD), high-resolution transmission electron microscope (HRTEM) and scanning electron microscope (SEM); and the electrical properties of the bulk samples were studied by AC impedance spectroscopy. Experimental results show that the substituent Y can stabilize the cubic β phase to room temperature; the bulk samples are dense and uniform with an average grain size from 60 nm to 4 μm; the highly dense bulk samples show enhanced ionic conduction, e.g. the conductivity of the sample with relative density 99% is 0.026 S/cm at 600 ℃, which is two times higher than that of bulk samples prepared by solid-state reaction. It can be concluded that the effect of sample density on the electrical conductivity is mainly due to the grain boundary conductivity; and the effect of sample grain size (from 60 nm to 4 μm) on the electrical properties is not so significant.
Investigations of structural phase transition, electronic structures and optical properties in ZnS
Authors: Li Jian-Hua  , Cui Yuan-Shun  , Zeng Xiang-Hua  , Chen Gui-Bin  ,   College of Physics and Electronic Electrical Engineering, Huaiyin Normal University, Huaian 223300, China;,   College of Physics Science and Technology, Yangzhou University, Yangzhou 225002, China
Published: December 2020

Equation of state and phase transformation under high pressure of ZnS in zinc blende (ZB) and rock salt (RS) structures have been calculated by means of plane wave pseudo-potential method (PWP) with generalized gradient approximation (GGA). The electronic density of states, band structure and optical properties of change mechanism have been discussed near the point of phase transformation. The results reveal that the transition pressure of ZnS from ZB to RS phase is 18.1 GPa by the equation of state, but it is 18.0 GPa obtained with the enthalpy equal principle. The sp3 hybrid orbital has not been eliminated and the metalic behavior of RS ZnS is enhanced significantly in the structural phase transition process. By comparing RS phase with ZB one, the main peak of the dielectric constant in RS ZnS becomes higher and shifts to the lower energy direction apparently, and other dielectric peaks are also extended to lower energy direction, at the same time the electronic transitions are enhanced in the low energy region.
Effects of bottom electrode on resistive switching characteristics of ZnO films
Authors: Li Hong-Xia  , Chen Xue-Ping  , Chen Qi  , Mao Qi-Nan  , Xi Jun-Hua  , Ji Zhen-Guo  ,   Laboratory of Electronic Materials and Devices, Hangzhou Dianzi University, Hangzhou 310018, China;,   State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310013, China
Published: December 2020

In this paper, thin films of ZnO were deposited on different bottom electrodes (BEs) by DC magnetron sputtering to fabricate resistive random access memory (ReRAM) with a W/ZnO/BEs structure. The effects of different BEs on the resistive switching characteristics of the fabricated device have been investigated. The results reveal that the devices fabricated on different BEs exhibit reversible and steady unipolar resistive switching behaviors. The conduction behavior in the low resistance state has an Ohmic behavior. However, the conduction mechanism in the high resistance state fits well with the classical space charge limited conduction. Schottky barrier heights between ZnO and different BEs have great effect on the operation voltages during the resistive switching processes. The resistances in low resistance state and the reset currents of the ZnO films fabricated on different BEs were discussed based on the filamentary model.
Fabrication and electrolytic conduction of single conical nanopores
Authors: Zhu Xiao-Rui  , Wang Wei-Dong  , Qin Guang-Yong  , Jiao Zhen  ,   Henan key laboratory of ion beam bioengineering, Physical engineering college Zhen Zhou University, Zhengzhou 450052, China
Published: December 2020

Single conical nanopores were fabricated by etching single-ion-irradiated polymer (ethylene terephthalate) (PET) films. The etching process was monitored by measuring the transmembrane current. A series of conical nanopores with different tip sizes were obtained at different maximum etching currents, "Imax". Results showed that it was possible to control the tip diameter by terminating etching at a certain Imax. The current-voltage characteristic of the nanopores in KCl solution was investigated. Results showed also that the ionic conduction was asymmetrical, this phenomenon is called rectification. The current rectification coefficient, was influenced by the tip size and electrolyte concentration.
A combined phenomenological model for secondary electron emission
Authors: Li Yong-Dong  , Yang Wen-Jin  , Zhang Na  , Cui Wan-Zhao  , Liu Chun-Liang  ,   Key Laboratory for Physical Electronics and Devices of the Ministry of Education, Xi’an Jiaotong University, Xi’an 710049, China;,   Science and Technology on Space Microwave Laboratory, Xi'an 710100, China
Published: December 2020

The accuracy of the model for secondary electron yield (SEY) has a remarkable influence on the simulation result of multipactor threshold. A new combined phenomenological model for SEY was proposed based on the corrected Vaughan model and Furman model. It combines virtues of the latter two models by integrating corrected Vaughan model into Furman model for its calculation of yield of true secondary electron. The new model provides high flexibility and accuracy to fit experimental data of SEY as a function. For comparison, experimental data of silver and aluminum alloys were tested with the three models. It was found that the fitting accuracy has been improved by at least 10% under the circumstances of different incident angles of the original electron.
Absorption and nonlinear optical properties of Te/TeO2-SiO2 composite films
Authors: Gan Ping  , Gu Min  , Qing Sheng-Lan  , Xian Xiao-Dong  ,   State Key Laboratory of Coal Mine Disaster Dynamics and Control, State and Local Joint Engineering Laboratory of Methane Drainage in Complex Coal Gas Seam, Chongqing University, Chongqing 400044, China;,   College of Communication Engineering, Chongqing University, Chongqing 400044, China;,   College of Automation, Chongqing University, Chongqing 400044, China
Published: December 2020

The transmission and absorption spectra of the Te/TeO2-SiO2 thin film were obtained by using a spectrophotometer, with the surface plasmon rensoance (SPR) observed at 480 nm. While the dependence of the third-order nonlinear susceptibility of composite films on the Te particle was investigated by Z-scan technique with renosant wavelength (532 nm) and non-renosant wavelength (1064 nm). Optical properties of these films was analyzed using the effective medium theory, and the relationship was investigated to obtain Te particle size and nonlinear optical properties of Te/TeO2-SiO2 films. The results show that the Te particle size was smaller, the number of particles was increased, and the particle distribution tends to be uniform. The surface plasmon resonance peak was red-shifted, and the absorption intensity was enhanced; and the third-order nonlinear optical effects was enhanced, χ(3) was increased by 5.12×10-7 esu at 1064 nm to 8.11×10-7 esu at 532 nm with preparation potential increased.
Investigation of an X-band over-moded bent circular waveguide TM01-HE11 mode converter
Authors: Xu Gang  , Xie Ping  , Liao Yong  ,   Science and Technology on High Power Microwave Laboratory, Institute of Applied Electronics CAEP, Mianyang 621900, China
Published: December 2020

In the application of low loss beam waveguides and high performance reflector antennas, high power microwave should be converted to quasi-Gaussian HE11 mode, to decrease side lobe level and increase feed coefficient. Based on the fact that TM01 mode converts to TE11 and TM11 mode at the same time in bent overmode circular waveguide, a TM01 to HE11 mode converter was proposed in this paper, which can convert TM01 mode to HE11 mode directly using a bent circular waveguide, the converter has higher power compacity than corrugated TE11-HE11 mode converter and more compact than TE11-TM01 mode converter added with smooth wall TE11-HE11 mode converter. The geometric parameters of the convertor were analyzed and optimized by using coupled mode theory and Taguchi method, to output the target modes content, 80% TE11 and 20% TM11 modes, which are primarily composed of HE11 mode. The optimized converter was analyzed using full electro-magnetic simulation method, the scalar Gauss ratio of the output beam is higher than 99% from 9.05 GHz to 9.8 GHz, the power capacity is as high as 4.5 GW.