bluuebunny/crossref_metadata_2025 huggingface dataset:
Design of an infrared dual-band search and tracking system operating in widen temperature range
Authors: Shen Man-De  , Ren Huan-Huan  ,   Wuhan Textile University, Wuhan 430073, China
Published: December 2020

Because a harmonic diffractive optical element has special achromatism and athermalization, it can be applied to infrared dual-band search and tracking optical system. In this paper, we make the device that can be used in the wavelength ranges 3.7—4.8 μm and 8.7—11.3 μm; It has an efficient focal length 200 mm, the F/number 2.5, the full field of view is 5°. The environment temperature can be changed between -80 ℃—200 ℃. The practical design shows that the system not only shows good image quality in mid-and long-wave, but also the advantages of compact structure, high rates of transmission and athermalization.
Concentration and size measurements of sprays with global rainbow technique
Authors: Wu Ying-Chun  , Wu Xue-Cheng  , Sawitree Saengkaewi  , Jiang Hao-Yu  , Hong Qiao-Qiao  , Gérard Gréhan  , Cen Ke-Fa  ,   State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, China;,   UMR 6614/CORIA, LABEX EMC3, Centre National de la Recherche Scientifique, Université et Institut National des Sciences Appliquées de Rouen,Site du Madrillet, Avenue de l'Université, BP 12 76801 Saint Etienne du Rouvray, France
Published: December 2020

Simultaneous measurement of the concentration and size of spray droplets plays an important role in understanding sprays. The global rainbow technique is applied to measure the concentration and size of bi-component droplets. Based on the modified Nussenzweig theory, the refractive index and size distribution are optimally evaluated, and then the concentration is retrieved with prior relationship between the refractive index and concentration. The inverse algorithm is verified by the simulated global rainbow signals; results shows that it can accurately retrieve the refractive index and size distribution of the droplets with an unimodal or bimodal particle size distribution. Sprays of water-ethanol solution with volume concentration from 0% to 100% are measured. Results show that the measured refractive indices agree well with the exact values, and the size distribution is stable. The global rainbow technique shows great potential in concentration measurement of spray droplets.
Effect of grain size on energy deposition process in Ni metal during 1 MeV electron irradiation
Authors: Ma Guo-Liang  , Li Xing-Ji  , Liu Hai  , Liu Chao-Ming  , Yang Jian-Qun  , He Shi-Yu  ,   School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China
Published: December 2020

The high performance nano-crystal Ni material was prepared by the pulse electrodeposition process; the intensity, composition and the microscopic structure of the nano-crystal Ni material were investigated by various measurements. In this paper, the 1 MeV electron was chosen as the irradiation source to investigate the energy loss of high energy electron in the nano-crystal Ni material and conventional bulk Ni material, and the energy deposition process during the electron irradiation was measured by the absorbed dose tablets. The results show that the grain size affects the energy loss process during the 1MeV electron irradiation seriously. The absorbed dose of 1 MeV electron in the nano-crystal Ni material is lower than that in the common Ni material with the same thickness, which indicates that the energy deposition of high energy electron in nano-crystal metal is lower than that in the conventional bulk metal, and the nano-crystal metal has an advantage of radiation resistance.
A new method for monitoring the average residence time of atmospheric particulate matter
Authors: Liu Ya-Chun  ,   School of Mathematical and Physical Science, University of South China, Hengyang 421001, China;,   School of Nuclear Science and Technology, University of South China, Hengyang 421001
Published: December 2020

The long life decay products 210Pb, 210Bi and 210Po of 222Rn are adsorbed in atmospheric particulate matters, thus making it possible to estimate the average residence time by measuring the specific activity or activity ratio of radon daughters. However, the existing research results are rather bad in consistency and the contradictory phenomena cannot be reasonably explained, which makes it inapplicable to atmospheric environmental monitoring. For this reason, starting with the basic attributes of lower atmosphere, based on the decay characteristics, transfer rates and other related information of radioactive nuclides in atmospheric particulates, a mathematical model is built to reflect the relationship among the particle numbers of the absorbed, decayed and transferred. Then, a new method is presented to estimate the average residence time of atmospheric aerosol. The method can solve the confusion that have appeared in the current research, reveal that the atmosphere has limited self-purification function, and provide the condition for nuclides in the same decaying chain to decay to the activity balance and the way to reduce the average residence time. All these conclusions will provide a scientific basis for further study and exploitation in atmospheric environment monitoring.
Potential energy surface and spectra prediction for the Mg-CO complex
Authors: Han Yu-Long  , Li Zhen  , Wang Jiang-Hong  , Feng Er-Yin  , Huang Wu-Ying  ,   College of Physics and Electronic Information, Anhui Normal University, Wuhu 241000, China
Published: December 2020

The interaction potential energy of Mg-CO complex was calculated by employing ab initio method in the single and double excitation coupled-cluster theory with noniterative treatment of triple excitations [CCSD (T)] and large basis sets. The potential energy surface expressed by an analytical function was obtained for the first time as far as we know. A single global minimum occurs at Re= 8.98a0 and θe= 119.09° at an energy of -72.21 cm-1, and the potential energy surface has a weak anisotropy. Based on the potential, the rovibrational energy level structure of the Mg-CO complex was investigated. The microwave transition frequencies and spectroscopic parameters for the Mg-CO complex were theoretically predicted.
Population transfer of HF molecules in the ground electronic state through multiphoton transition
Authors: Wang Rong  , Xiu Jun-Ling  , Niu Ying-Yu  ,   School of Science, Dalian Jiaotong University, Dalian 116028, China
Published: December 2020

The multiphoton transition is investigated theoretically by using wave packet method for the ground electronic state of HF molecule. A laser field composed of two overlapping infrared pulses is used in our model, and the ratio of their frequencies is 1:2. States |4,0> and |4,2> are chosen as target states. Calculated results show that the population can be transferred to different target states as the corresponding resonant frequency is chosen. The probability of the population transfer can be controlled by the initial phase difference of the two pulses. When the initial phase difference is of an odd number of π/2, the probability of population transfer reaches the maximal value. When the initial phase difference is of an even number of π/2, the probability of population transfer reaches the minimum value. In comparison with the state |4,2>, the initial phase difference has a stronger in fluence on the population of the state |4,0>.
Simulation of high gain high harmonics oscillator with optical klystron free electron laser
Authors: Gu Xiao-Wei  ,   School of Info Sci & Tech, Zhejiang Sci-Tech University, Hangzhou 310018, China
Published: December 2020

A possibility of new structure for high harmonics high gain (HGHG) free electron laser is proposed, in which the structure of the optical klystron is placed in the resonance cavity to form the HGHG modulator. This particular modulator can remove seed laser of the conventional HGHG. Such a scheme will be beneficial to high-repetition-rate, full coherence and narrow bandwidth. Detail simulation by GINGER was given, showing that up to 12 harmonics the output of the oscillator is still very well.
Modification from the spin to the synchrotron radiation from a relativistic electron
Authors: Li Yi-Ding  , Zhang Peng-Fei  , Zhang Hui  , Xu Hong-Liang  ,   National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, China;,   CAS Key Laboratory of Basic Plasma Physics, Department of Modern Physics, University of Science and Technology of China, Hefei 230029, China
Published: December 2020

An explicit expression for the spectral distribution of the radiation energy from a relativistic electron with a magnetic moment is derived. Consequentially for an extreme relativistic electron moving along a planar circular orbit, the spectral distributions of synchrotron radiation in σ- and π- polarization are calculated including the modification from electron's magnetic moment. It is shown that for the synchrotron radiation with high critical frequency ωc with ħωc≥ 10 keV, the modification may be considerable. The relationship between the polarization of synchronous electrons and radiation fields is obtained, and thus the information about spin polarization of electron beam from measuring the polarization of radiation fields is provided.
A reflective grism pair stretcher for chirped pulse amplification
Authors: Guo Shu-Yan  , Ye Peng  , Teng Hao  , Zhang We  , Li De-Hua  , Wang Zhao-Hua  , Wei Zhi-Yi  ,   Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
Published: December 2020

A new reflective grism, which combines together the grating and prism, is introduced in this paper. The numerical simulation, based on the ray tracing, shows that the grism pair can introduce minus GVD and GDD; therefore it can well compensate for the material dispersions in the chirped pulse amplifier (CPA). Compared to the conventional CPA with up-chirp, the new scheme with down-chirp can support a near Fourier Transform-limited compressed pulse due to much better compensation for high-order dispersion of materials in amplifier, in which the grism acts as the stretcher and the ZF7 bulk material as the compressor. In addition, the improved transmission efficiency and simplified configuration makes it a promising way to amplify femtosecond laser pulses to sub-mJ at a high repetition rate.
Study on the distribution properties of image plane speckle fields produced by Gaussian correlation weak scattering screens
Authors: Liu Man  ,   School of science, Shandong polytechnic university Jinan 250353, China
Published: December 2020

Far-field speckle generated by weak scattering screen is a central bright spots, around which is a speckle structure similar to the normal speckle. According to the far-field speckle produced by weak scattering screen, it is assumed that the image plane speckle of weak scattering screen is the result of coherent superposition of both uniform background and normal speckle. However, there exists a discrepancy between the assumption and the actual image plane speckle. Based on the above circumstances, the statistical properties are studied about the image plane speckle fields produced by Gaussian correlation weak scattering screens in the 4f optical imaging system of high-pass filter. It is found that the above assumption is correct when the surface roughness of the weak scattering screen and the wavelength of the incident light wave are almost the same.
Average intensity of tilted and off-axis Gaussian Schell-model beams propagating through a cat-eye optical lens in atmospheric turbulence
Authors: Ma Yuan  , Ji Xiao-Ling  ,   Department of Physics, Sichuan Normal University, Chengdu 610068, China
Published: December 2020

The influences of atmospheric turbulence and the beam coherence on the average intensity of tilted and off-axis laser beams propagating through a cat-eye optical lens in the turbulence are studied. It is shown that the oscillatory behavior and the skewness of average intensity may appear because there exist apertures and active detection laser beams are tilted or off-axis. The skewness is independent of turbulence, but the oscillatory behavior disappears due to turbulence. For a small positive defocus of a cat-eye optical lens, the on-axis average intensity reaches its maximum. The a positive defocus value becomes small as the focal length of the cat-eye optical lens decreases, but it is independent of atmospheric turbulence and the coherence of active detection laser beams. And the average intensity becomes an off-Gaussian-like profile when the propagation distance is large enough in turbulence. However, less beam spreading may occur with increasing propagation distance for active detection laser beams with less coherence, which is quite different from the behavior of laser beams propagating in free space. The better the coherence of active detection laser beams is, the more the average intensity is affected by the turbulence, but the difference is small. The results obtained in this paper are very useful for the applications is active laser detection.
The integral variational principles for embedded variation identity of high-order nonholonomic constrained systems
Authors: Song Duan  , Liu Chang  , Guo Yong-Xin  ,   Physics of medical imaging department, Eastern Liaoning University, Dandong 118001, China;,   College of Physics, Liaoning University, Shenyang 110036, China
Published: December 2020

In this article, from the integral variational principles for embedded variation identity of high-order nonholonomic constrained systems, three kinds of dynamics for high-order nonholonomic constrained systems are obtained, including the vakonomic dynamical model, Lagrange-d'Alembert model and a new one if utilizing respectively three kinds of conditional variation to them. And the integral variational principles for embedded variation identity of high-order nonholonomic constrained systems is also fitted for the general nonholonomic systems when the constrained equation is reduced to a first-order one. Then, the vakonomic dynamic, Chetaev dynamics and a new model of general nonholonomic systems can also be obtained. Finally, two illustrated examples are used to verify the validity of the theory.
Dynamical and structural properties of two-dimensional dusty plasma with modified screened coulomb potential
Authors: Zhang Chong-Long  , Kong Wei  , Yang Fang  , Liu Song-Fen  , Hu Bei-Lai  ,   Department of Physics, Nankai University, Tianjin 300071, China;,   Department of Chemistry, Nankai University, Tianjin 300071, China;,   College of Science, Civil Aviation University of China, Tianjin 300300, China
Published: December 2020

The modified screened Coulomb potential is obtained with considering the changes of plasma number density. Both the analytical results and molecular dynamical simulation show that the modification due to the changes of number density has a minor effect on the dynamical and structural properties of the two-dimensional dusty plasmas. However, further modifications including such as the particle size, ion drag force and pressure force possibly change the profile of the spherically asymmetric Coulomb potential. Motivated by the above speculation, the modified screened Coulomb potential with a set of margin parameters is used to investigate the dynamical and structural properties of the two-dimensional dusty plasmas. It is found that the diffusion of system is extensively decreased, particularly, a circle configuration is formed, which is similar ho the experimental observation of spherical assemble. Additionally, a uniform magnetic field is used to investigate the effects on the dynamical and structural properties of the two-dimensional dusty plasmas.
Kondo effect on the electrical transport properties of carbon nanotubes
Authors: Li Zhen-Wu  ,   School of JiangZhen Mechanical and Electrical Engineering, Heze University, Heze 274015, China
Published: December 2020

Based on the influence of Kondo effect in carbon nanotubes, the Anderson model was used to characterize the system of carbon nanotubes/magnetic impurity at a finite temperature. The electric conductivity and the thermopower in the system of carbon nanotubes/magnetic impurity were researched by using the Landauer formula. The results of theoretical calculation agree well with that of experimental research.
Generation mechanism of two different over-saturation phenomena of photovoltaic HgCdTe detectors irradiated by CW band-in laser
Authors: Jiang Tian  , Cheng Xiang-Ai  , Xu Zhong-Jie  , Lu Qi-Sheng  ,   College of Optoelectric Science and Engineering, National University of Defense Technology, Changsha 410073, China;,   Science and Technology on Electro-Optical Information Security Control Laboratory, Sanhe 065201, China
Published: December 2020

We have studied two batches of photovoltaic HgCdTe detectors irradiated by CW band-in laser, and discovered, two different over-saturation phenomena. It is shown that the over-saturation phenomenon associated with the open-circle voltage signals which decreases with increasing light intensity is of universal existence in the PV HgCdTe detectors irradiated by intense light. The regular and special phenomena of PV HgCdTe detectors under intense light radiation are definite and obvious. The generation conditions for the two typical over-saturation phenomena are analyzed in terms of the equivalent circuit model. These two kinds of over-saturation phenomena have been numerically simulated. Numerical results are in good agreement with experimental data. It is found that the two generation mechanisms of the over-saturation phenomena of PV detector under irradiation of the above-band gap laser do exist. One is the increasing dark current due to thermal effectm, and the other is the leak current due to the bugs in the detector material.
Numerical simulation of vortex structure in mesoscopic two-gap superconductor
Authors: Shi Liang-Ma  , Zhang Shi-Jun  , Zhu Ren-Yi  ,   College of Electronic Engineering & Electricial Automation, Chaohu University, Chaohu 238000, China
Published: December 2020

In this paper, the evolution of vortex configuration for mesoscopic two-gap superconductor is investigated by the time-dependent Ginzburg-Landau theory in the presence of an externally applied field. The vortex configurations of s-wave and d-wave, and the distribution of magnetic field are given when the temperature is between critical temperatures of s-wave and d-wave. In theory, the over-cold and the over-hot field, and the boundary effect on vortex are simulated when the magnetic flux penetrates the superconductor.
Temperature-dependent Raman spectroscopic study on orthophosphates Ba3(PO4)2 and Sr3(PO4)2
Authors: Zhang Ji  , Wang Di  , Zhang De-Ming  , Zhang Qing-Li  , Wan Song-Ming  , Sun Dun-Lu  , Yin Shao-Tang  ,   Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China;,   Graduate School of the Chinese Academy of Sciences, Beijing 100049, China;,   Nahui Xin Hua University, Hefei 230088, China
Published: December 2020

Temperature-dependent Raman spectroscopic study on orthophosphates Ba3(PO4)2 and Sr3(PO4)2 were carried out up to 900 ℃. The change of Raman lines and crystal structure has been investigated at high-temperatures. It is found that all the Raman lines exhibit a decrease in frequency shifts and the width of the Raman lines increases with the increase in temperature. The P-O bond lengths in the crystal increase in high- temperature, but the O-P-O bond angles have less change. No phase changes have been observed under 900 ℃.
Decoding the neural activity of dorsal spinal nerve root evoked by acupuncture at Zusanli point based on the generalized linear model
Authors: Xue Ming  , Wang Jiang  , Deng Bin  , Wei Xi-Le  , Chen Ying-Yuan  ,   School of Electrical and Automation Eng., Tianjin University, Tianjin 300072, China
Published: December 2020

Neural system can characterize the information evoked in external stimulations by spatiotemporal encoding. Acupunctureas, as a mechanical actionis equivalent to an external stimulus to the neural system. In order to decipher how neural systems represent and transmit acupuncture information, experiments are designed such that different frequencies of manual acupuncture (MA) manipulations can be given to ‘Zusanli’ point of an experimental rat, and the induced electrical signals in spinal dorsal root ganglion are detected and recorded. First, the spike trains are obtained by data preprocessing and transformed into point process trains. Then a generalized linear model is introduced to encode the acupuncture information and produce the simulated neural spike train. In addition, a Bayesian decoding algorithm is used to reconstruct the displacement oscillograms of the acupuncture needle from the neural point process spike train. Finally, the quantile-quantile (Q-Q) plot based on the time-rescaling theorem is used to evaluate the agreement between the encoding model and the point process data. Results prove to be valid based on statistical analysis. These studies have offered new insights into neural processing underlying acupuncture and have implementations for constructing the interface between neural systems and machines and improving the clinical study.
Efficient reconstruction from truncated data in circular cone-beam CT
Authors: Wang Xian-Chao  , Yan Bin  , Liu Hong-Kui  , Li Lei  , Wei Xing  , Hu Guo-En  ,   National Digital Switching System Engineering and Technological Research Center, Zhengzhou 450002, China;,   Faculty of Infrastructure Engineering, Dalian University of Technology, Dalian 116000, China
Published: December 2020

In circular cone-beam computed tomography (CT), to solve the 3D image reconstruction from truncated projection data which has no truncation along PI-line, backprojection-filtration (BPF) algorithm is a preferred choice. However, in its performance the integral interval of backprojection is variable for different PI-line, rendering the parallelism performance of backprojection low. So it cannot satisfy the requirement of fast image reconstruction in practical CT system. In this paper, a tent BPF (T-BPF) algorithm is developed based on the data rebinning method, which was performed by first rearranging the cone-beam data to tent-like parallel-beam data, and then applying the proposed BPF-type algorithm to reconstruct images from the rearranged data. T-BPF turns the variable view-angle integral interval of backprojection into a fixed integral interval, and there are no relations in the loops of backprojection calculation, which means the parallelism performance of T-BPF is an improvement over that of the original BPF algorithm. The results of experiments show that compared with the conventional CPU implementation, the GPU accelerated method provides images of the same quality with a speedup factor 1036 for the reconstruction of 2563 Shepp-Logan model. The speedup factor is an improvement in the original BPF algorithm. T-BPF provides a solution for the 3D fast reconstruction from truncated data.
Bulk transfer coefficients of momentum and sensible heat over semiarid grassland surface and their parameterization scheme
Authors: Yue Ping  , Zhang Qiang  , Li Yao-Hui  , Wang Run-Yuan  , Wang Sheng  , Sun Xu-Ying  ,   Key Laboratory of Arid Climate Change and Reducing Disaster of Gansu Province, Key Laboratory of Arid Climate Change and Reducing Disaster of CMA, Institute of Arid Meteorology, CMA, Lanzhou 730020, China;,   Zhangye National Meteorological Observatory, Zhangye 734000, China
Published: December 2020

The momentum and heat transfer coefficients used in the atmospheric numerical models usually are taken as constants. In fact, the bulk transfer coefficients change not only with atmospheric stabilities, but also with the air motion and thermodynamic properties of the surface boundary layer. In this paper, the bulk transfer coefficients of momentum and sensible heat are determined by using the data observed by the eddy correlation system and those of the average wind velocity and temperature gradients over the Xilin Guole semiarid grassland in May, 2008. The relations between the bulk transfer coefficients and the gradients in Richardson numbers are analyzed, and the relationship between the bulk transfer coefficients and atmospheric stabilities is also studied. Finally, the changes of momentum bulk transfer coefficients with wind speed and the relations between sensible heat transfer coefficients and temperature are determined. Comparison with the eddy correlation method for observing transfer coefficients, there is a great difference between the computational values of typical Businger-Dyer similarity functions. The revised Monin-Obukhov similarity functions could significantly improve the accuracy of the transfer coefficients. Under the near neutral stratification, there was an obvious interaction between the land surface and the flow condition over semiarid regions. The momentum bulk transfer coefficient varies with the mean wind speed at 10 m according to the quadratic curve laws. Under the low wind velocity condition, the influence of the air flow on the roughness was not significant and the momentum transfer coefficient will increase with increasing wind velocity. While at the high wind speed, the momentum transfer coefficient will decrease with increasing wind velocity, for the air flow changes the roughness height of surface boundary layer. Under the near neutral stratification, there was a quadratic curve law between the temperature and the sensible heat transfer coefficient, which provides a useful parameterization scheme for sensible heat transfer coefficient. The new schemes could parameterize the turbulent fluxes with average wind velocity and temperature gradients data, and does not need to compute the roughness.
Radar sea clutter power modeling under the atmospheric duct propagation conditions
Authors: Zhao Xiao-Feng  , Huang Si-Xun  ,   Institute of Meteorology, PLA University of Science and Technology, Nanjing 211101, China
Published: December 2020

Taking into account the variations of the refractivity gradient near the sea surface, We have used the curved wave spectral estimation (CWSE) technique to calculate the grazing angle. CWSE combined with the modified GIT reflectivity model and radar range equation, the radar sea clutter power modeling is performed under the atmospheric duct propagation conditions. Finally, the validation of CWSE is tested through numerical experiments and comparisons with the real measurement data.
Speckle reduction by image entropy anisotropic diffusion
Authors: Li Jin-Cai  , Ma Zi-Hui  , Peng Yu-Xing  , Huang Bin  ,   School of Computer Science, National University of Defense Technology, Changsha 410073, China;,   Education Technology Center, Changsha Normal College, Changsha 410100, China;,   Department of Computer Science, Huaihua College, Huaihua 418008, China
Published: December 2020

Edge detection is the focus and difficult point for speckle reduction anisotropic diffusion. Traditional methods typically rely on the estimation of mean and variance in edge detection. The precision of the estimations influences the accuracy of edge detection. In this paper, we present an anisotropic diffusion filter based on image entropy. This method uses image entropy as an edge detector to eliminate the error due to the estimation of mean and variance, and improves the edge detection capability. The experimental results show that the visual quality and evaluation indexes of the new method outperform those of the traditional methods.
Super-harmonic resonance of fractional-order van der Pol oscillator
Authors: Wei Peng  , Shen Yong-Jun  , Yang Shao-Pu  ,   Department of Mechanical Engineering, Shijiazhuang Tiedao University, Shijiazhuang 050043, China
Published: December 2020

The dynamical characteristics of super-harmonic resonance of van der Pol oscillator with fractional-order derivative are studied. First the approximate analytical solution are obtained by the averaging method, and the definitions of equivalent linear damping and equivalent linear stiffness for super-harmonic resonance are established. Effects of the fractional-order parameters on the dynamical characteristics of the system are also studied through the equivalent linear damping and equivalent linear stiffness. Moreover, the amplitude-frequency equation and the stability condition for the steady-state solution are analytically presented, and the definitions of equivalent nonlinear damping coefficient and nonlinear stability parameter are also established. Finally, the comparisons of the fractional-order and the traditional integer-order van der Pol oscillators are carried out by numerical simulation. The effects of the parameters in fractional-order derivative on the steady-state amplitude, the amplitude-frequency curves, and the system stability are also analyzed.
Oscillation behaviors and mechanism of Rayleigh oscillator with periodic switches
Authors: Chen Zhang-Yao  , Xue Zeng-Hong  , Zhang Chun  , Ji Ying  , Bi Qin-Sheng  ,   Faculty of Civil Engineering and Mechanics, Jiangsu University, Zhenjiang 212013, China
Published: December 2020

A system, which alternates between autonomous and non-autonomous circuit systems observing the time periodic switched rules, is investigated in order to explore its complicated dynamical behaviors. By analyzing the equilibrium point, limiting cycles, and the stability of the autonomous subsystems, as well as deriving the Lyapunov exponents of the switching systems in theory and numerical calculation, we have studied the variation of periodic oscillation behaviors of the compound systems with different stable solutions to the two subsystems. By using the bifurcation diagram of the switched systems and their corresponding largest Lyapunov exponent diagrams, we can observe the complex dynamical behaviors and oscillating mechanism of alternating periodic oscillations, quasi-periodic oscillations and chaotic oscillations with different parameters in the switched systems. Furthermore, dynamical evolutions of the switching system to chaos by period-doubling bifurcations, saddle-node bifurcations and torus bifurcations are observed.
Study on nonlinear phenomena in dual buck full-bridge inverter
Authors: Liu Hong-Chen  , Su Zhen-Xia  ,   School of Electrical Engineering and Automation, Harbin Institute of Technology, Harbin 150001, China
Published: December 2020

Dual buck full-bridge inverter has the following advantages: it has no shoot-through problem, but receives high-utilization of DC input voltage, high efficiency and optimum selection of the freewheeling diodes, hence it attracts more and more attention in high power applications. In this paper, the bifurcation and chaos in the dual buck full-bridge inverter is studied. The two-dimensional discrete iterated mapping model under proportional control is established and stroboscopic maps in different periods of time are obtained. Effects of the proportional coefficient k on system performance are analyzed by using bifurcation diagram and folded diagram. A simulation model of dual buck full-bridge inverter is established based on Matlab/Simulink and the time domain waveforms and phase-space portraits for different proportional coefficient k are obtained. Besides, the effects of the bifurcation and chaos on the spectrum of the system are analyzed. Finally, the nonlinear behavior in the inverter caused by the variation of other circuit parameters such as input voltage E, inductance L, and the switching period of carrier wave T is discussed through bifurcation diagrams. Results show that the correct choice of circuit parameters of dual buck full-bridge inverter is very important for its stable operation.
Vibrational resonance in a Duffing system with fractional-order external and intrinsic dampings driven by the two-frequency signals
Authors: Zhang Lu  , Xie Tian-Ting  , Luo Mao-Kang  ,   Department of Mathematics, Sichuan University, Chengdu 610065, China;,   Science and Technology on Electronic Information Control Laboratory, Chengdu 610036, China
Published: December 2020

The phenomenon of vibrational resonance (VR) in a Duffing system with both fractional-order external damping and fractional-order intrinsic damping driven by the two-frequency periodic signals is investigated. It is observed that the resonance amplitude Q can be optimized by an appropriate choice of the amplitude of the high-frequency signal. The obtained relationship between VR and the fractional-orders shows that both fractional-order external damping and fractional-order intrinsic damping can induce changes of the shapes of the effective potential function and then lead to more abundant resonance behaviors than in the traditional dynamic systems.
Theory and simulations of high frequency characteristics for a staggered double-grating slow-wave structure with step-shaped grooves
Authors: Xie Wen-Qiu  , Wang Zi-Cheng  , Luo Ji-Run  , Liu Qing-Lun  , Li Xian-Xia  ,   Institute of Electronics, Chinese Academy of Sciences, Beijing 100190, China;,   University of Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

Based on a staggered double-grating slow wave structure with step-shaped grooves, the expressions of the electromagnetic field in it have been obtained and the formulae of the dispersion equation and coupling impedance have been solved by means of field matching method. As an example, a staggered double-grating slow wave structure for W band TWT application was used to calculate the characteristics of dispersion and coupling impedance using the formulae and CST-MWS code, and analyze the effect of the step dimension variation on the high frequency characteristics. Results show that the theoretical calculations are in good agreement with the CST-MWS code simulations, and the slow wave structure can improve the dispersion characteristics, enhance interaction bandwidth, while keeping a proper coupling impedance and mechanical intensity, which can to some extent compensate for the deficiency in the staggered double-grating slow wave structure with the rectangular-shaped grooves.
A novel frequency selective surface with stable performance and its application in microstrip antenna
Authors: Yuan Zi-Dong  , Gao Jun  , Cao Xiang-Yu  , Yang Huan-Huan  , Yang Qun  , Li Wen-Qiang  , Shang Kai  ,   Information and Navigation Institute of Air Force Engineering University, Xi’an 710077, China
Published: December 2020

A novel frequency selective surface(FSS) with stable performance is designed and applied to microstrip antenna. The FSS cell is composed of two metallic layers separated by a dielectric spacer. The top and bottom layers connected with metallic cylinders form the fractal dendritic model. By optimizing the geometric parameters of the model, an ultra-thin FSS spatial filter is obtained, whose thickness is only 0.017λ, with wideband, polarization insensitive, wide-incident angle, and miniaturization properties. When applying the radome to microstrip antenna, the bandwidth of the antenna is improved to 40%, the gain is enhanced in the whole operating frequency band, especially at 9.6 GHz, the gain is increased by 6.7 dB; at the same time, the in-band radar cross section(RCS) is reduced significantly, and the largest reduction exceeds 12.7 dB. Experimental results are in good agreement with the simulated ones, which verifies that the novel FSS spatial filter can be used to increase the gain of broadband antenna, enhance the directivity, improve the bandwidth, and reduce the in-band RCS; to sum up, it can be applied to broadband antennas to improve their radiation as well as scattering performance at one time.
Influence of inner windows on near-field shielding effectiveness of rectangular cavity with apertures
Authors: Fan Jie-Qing  , Hao Jian-Hong  , Qi Pei-Hua  ,   School of Electrical and Electronic Engineering, North China Electric Power University, Beijing 102206, China
Published: December 2020

Influence of the inner windows on the shielding effectiveness of a cavity with apertures is investigated by using the adjusted transmission line method (TLM). Electric shielding effectiveness is calculated as a function of the opening width of metal windows. It is shown that the electric near-field shielding effectiveness of a cavity with inner windows and apertures is far inferior to that of far-field. Results also show that the near-filed shielding effectiveness increases with the decrease of the opening width of the inner window, and the capacitive windows may lower the resonance frequency while the inductive windows may enhance. Results of the adjusted TLM are in good agreement with the CST simulation results.
Review on stretchable and flexible inorganic electronics
Authors: Feng Xue  , Lu Bing-Wei  , Wu Jian  , Lin Yuan  , Song Ji-Zhou  , Song Guo-Feng  , Huang Yong-Gang  ,   AML, Department of Engineering Mechanics, Tsinghua University, Beijing 100084, China;,   Center for Mechanics and Materials, Tsinghua University, Beijing 100084, China;,   State Key Laboratory of Electronic Thin films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, Sichuan 610054, China;,   Department of Mechanical and Aerospace Engineering, University of Miami, Miami, Florida 33146, USA;,   Institute of Semiconductor, Chineses Academy of Science, Beijing 100083, China;,   Department of Civil and Environmental Engineering and Department of Mechanical Engineering, Northwestern University, Evanston, IL 60208, USA
Published: December 2020

In order to meet the further demand of the next-generation electronic devices in the transplantable, lightweight and portable performances, flexible and stretchable inorganic electronics attract much more attention in both industry and academia in recent years. Compared to organic electronics, stretchable and flexible inorganic electronics are fabricated with the integrated structures of inorganic components on complaint substrates, which own the stretchability and flexibility via mechanical design. Thus stretchable and flexible inorganic electronics have the high electron mobility and excellent conformability to non-planar environment subjected to large deformation. This paper reviews the recent progress on principle, design based on mechanics, integration based on transfer printing and the reliability analysis of stretchable and flexible inorganic electronics. Finally, the prospective is also described for future application in bioengineering and medicine.
Ti：sapphire pumped passively mode-locked Tm：YAG ceramic laser
Authors: Zhan Min-Jie  , Zou Yu-Wan  , Lin Qing-Feng  , Wang Zhao-Hua  , Han Hai-Nian  , Lü Liang  , Wei Zhi-Yi  , Zhang Jian  , Tang Ding-Yuan  ,   Laboratory of Optical Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China;,   School of Technical Physics, Xidian University, Xi’an, 710071, China;,   School of Electrical and Electronic Engineering, Nanyang Technological University, 639798, Singapore
Published: December 2020

A passively mode-locked Tm:YAG ceramic laser was demonstrated. Employing a 6 at.% Tm3+-doped sample with a length of 2.7 mm, we have realized stable mode-locked pulses with a repetition rate of 109 MHz by a semiconductor saturable absorber. A maximum output power of 116.5 mW was obtained at the central wavelength of 2007 nm. The corresponding pulse duration was determined to be 55 ps by a self-built noncollinear intensity auto-correlation setup. It is shown that Tm:YAG ceramics are excellent laser materials which can be used in ultrafast lasers with high-power and high-efficiency output.
Research and design of thermal cloak in arbitary shape
Authors: Mao Fu-Chun  , Li Ting-Hua  , Huang Ming  , Yang Jing-Jing  , Chen Jun-Chang  ,   Wireless Innovation Lab of Yunnan University, Kunming 650091, China;,   School of Electronic Engineering, Beijing University of Posts and Telecommunications, Beijing 100876, China
Published: December 2020

On the basis of transformation thermodynamics, a thermal conductivity expression for cylindrical thermal cloak with arbitrary cross section is derived. Based on the expression, we design a thermal cloak with a non conformal section profile. Results of full wave simulation show that the cloak possesses heat protection function, since it is capable of guiding heat fluxes to travel around its inner domain, leaving the inner region untouched; meanwhile, the heat fluxes return to their original pathways, resulting in a perfect thermal invisible effect. Arbitrary shaped cylindrical thermal cloak with conformal or non-conformal cross section can be designed based on the derived thermal conductivity expression, and all of them have perfect thermal protection and invisibility functions. It is indicated that the derived conductivity expression is applicable to designing cylindrical thermal cloaks with an arbitrary cross section. The generality of this method has been confirmed, and it may have potential applications in the designing of thermal protection devices for computer chips and satellite, etc.
The rising motion of grains in a vibrating pipe
Authors: Zhang Fu-Weng  , Wang Li  , Liu Chuan-Ping  , Wu Ping  ,   School of Mechanical Engineering, University of Science and Technology Beijing, Beijing 100083, China;,   Beijing Engineering Research Center for Energy Saving and Environmental Protection, University of Science and Technology Beijing, Beijing 100083, China;,   Department of Physics, University of Science and Technology Beijing, Beijing 100083, China
Published: December 2020

The rising motion of grains in a vibrating pipe is studied experimentally and by DEM (discrete element method) simulations. A pipe is partially inserted into a static granular layer. With the pipe initially filled with a certain height of grains, when the pipe is set into vertical vibrations, grains in the pipe will rise along the pipe and the motion will be finally stabilized at a certain height. The rising height and the speed of motion are strongly dependent on the vibration strength. By using a high speed camera and through DEM simulation, the trajectory of individual grains and the force acting on the grains in each vibration cycle can be obtained. A force-based mechanism for this rising motion is proposed. During vibrations of the pipe, the grains in the pipe are compacted and loosened alternately, and the force of the pipe and the grains varies periodically, thus leading to the rising motion of grains. A new possible way of continuously transporting grains is presented in this work.
Analysis of a novel dual-mode large-mode-area micro-structured fiber
Authors: Chen Yan  , Zhou Gui-Yao  , Xia Chang-Ming  , Hou Zhi-Yun  , Liu Hong-Zhan  , Wang Chao  ,   Laboratory of Nanophotonic Functional Materials and Devices, Guangzhou 510006, China;,   State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004, China
Published: December 2020

A novel dual-mode large-mode-area micro-structured fiber is proposed. The characteristics of mode field distribution, effective area of fundamental mode, and bending loss based on FEM (finite element method) are analyzed. And the effects of all structured parameters on the confinement loss and effective area are discussed. Results show that this structure makes the first HOM (LP11) and the second mode(EH11) cut off, and it achieves dual-mode transmission in the fiber by adjusting the structural parameters. The effective area of a fundamental mode is approximately 700 μm2. The dual-mode large-mode-area micro-structured fiber can be used in large-capacity fiber transmission.
Study on the blood embolism in the bifurcation pipe by the lattice Boltzmann method
Authors: Shi Juan  , Wang Li-Long  , Zhou Jin-Yang  , Xue Ze  , Li Hua-Bing  , Wang Jian  , Tan Hui-Li  ,   School of Information and Communication Engineering, Guilin University of Electronic Technology, Guilin 541004, China;,   School of Material Science and Engineering, Guilin University of Electronic Technology, Guilin 541004, China;,   College of Physical Science and Technology, Guangxi Normal University, Guilin 541004, China
Published: December 2020

The mechanism of blood embolism formation always attracts the attention of researchers. Through calculating rigid particle movement in a bifurcated pipe, the blood flow as well as blood embolism in a bifurcated pipe are simulated preliminarily, and the flow speed and the probability to form thrombus are investigated. We can draw a conclusion that the higher the hematocrit is, the easier the blood is to form embolism, meanwhile, the bigger the pressure difference, the harder the blood is to form embolism. We also find that the embolism tends to occur at the entrance of a bifurcated pipe and bifurcation forming place. Beyond the bifurcation place, the hematocrit of the blood in a big tube is larger than that in a small tube.
Influence of channel length on PD SOI PMOS devices under total dose irradiation
Authors: Liu Hong-Xia  , Wang Zhi  , Zhuo Qing-Qing  , Wang Qian-Qiong  ,   Key Laboratory of Ministry of Education for Wide Band-Gap Semiconductor Material and Devices, School of Microelectronics, Xidian University, Xi’an 710071, China
Published: December 2020

This paper mainly investigates the total dose irradiation effects on 0.8 μm PD SOI PMOS devices which are exposed to 60Co γ-rays at a dose rate of 50 rad(Si)/s. The channel length dependence of SOI PMOS devices at total dose irradiation is investigated. The result shows that the threshold voltage shift is only a little larger for shorter channel devices at the same total dose. However, the degradation of maximum transconductance for shorter channel devices is more significant. We found that the oxide-trapped charge is the main factor impacting the threshold drift. We may conclude that a short channel device can produce more interface trapped charges by using the subthreshold separation technology.
Molecular dynamics simulation of polycrystal silver nanowires under tensile deformation
Authors: Yuan Lin  , Jing Peng  , Liu Yan-Hua  , Xu Zhen-Hai  , Shan De-Bin  , Guo Bin  ,   School of Materials Science and Technology, Harbin Institute of Technology, Harbin 150001, China
Published: December 2020

Metal silver in the nanoscale range is widely used in the fields, such as microelectronics, optoelectronics, catalysis etc., due to its unique electrical and thermal conductivity, especially in nano-electrodes and nano-devices. Tensile deformation behavior of polycrystalline silver nanowires, in various grain size, is simulated using molecular dynamics method. Effect of grain size on elastic modulus, yield strength, and plastic deformation mechanism of polycrystalline silver nanowire is analyzed in detail. Results indicate that polycrystalline silver nanowires show a softening for grain sizes smaller than 13.49 nm, a reverse Hall-Petch relationship. At this stage, the plastic deformation is dominated by ‘sliding’ at the grain boundaries and rotating of grains; moreover, a five-fold twin is formed at the later stage of deformation. While the plastic deformation mechanism changes to dislocation sliding, when the grain size is larger than 13.49 nm, and a large number of twins are formed at the later stage of deformation.
Charge model of strained Si NMOSFET
Authors: Zhou Chun-Yu  , Zhang He-Ming  , Hu Hui-Yong  , Zhuang Yi-Qi  , Lü Yi  , Wang Bin  , Wang Guan-Yu  ,   Key Laboratory for Wide Band-Gap Semiconductor Materials and Devices, School of Microelectronics, Xidian University, Xi’an 710071, China;,   College of Electronic Engineering, ChongQing University of Posts and Telecommunications, Chongqing 400065, China
Published: December 2020

Based on the structure of strained Si/SiGe NMOSFET, a unified charge model is presented, in which charge conservation is guaranteed by using the charge as the state variable. The model describes device characteristics from subthreshold to strong inversion as well as from the linear to the saturation operating regions using a smoothing function, and guarantees the continuities of charges and capacitances. Furthermore, capacitance models have been presented using Verilog-A, a language to describe analog behavior. Comparisons between the model and measured data show that the charge model can describe the device characteristics well. The proposed model is useful for the design and simulation of integrated circuits made of strained Si.