bluuebunny/crossref_metadata_2025 huggingface dataset:
3D numerical simulations of the 110 GHz, 220 GHz coaxial cavity double-beam gyrotron
Authors: Xia Meng-Zhong  , Yan Yang  , Liu Da-Gang  , Wang Ping  , Huang Pei-Pei  , Liu La-Qun  , Wang Hui-Hui  ,   Institute of Physical Electronics, University of Electronic Science and Technology of China Chengdu 610054, China
Published: December 2020

Since to break the limitation of traditional single anode magnetron injection electron gun can only produce a lower power, this paper, based on an independent research and development of particle simulation software CHIPIC, will take the 110 GHz, 220 GHz coaxial cavity double-beam gyrotron for full three-dimensional numerical simulation study. By theoretical analysis for the initial parameters of the coaxial double-beam electron gun and to optimize the design by CHIPIC, we obtain the high-performance electron beam with the horizontal and vertical velocity ratio of 1.0 and the maximum velocity spread of 5.4%, and use the optimized electron gun to replace the traditional gyrotron emission for numerical simulation of the 110 GHz, 220 GHz gyrotron system, as well as the four-process parallel MPI in computing. Finally we obtain that the double bands are 110 and 220 GHz respectively, a TE02 mode, and the average output power about 70 kW. The efficiency can reach 8.75% for the high performance double-beam gyrotron oscillating tube.
Three-dimensional numerical simulation of the single-channel pulsed-power vacuum device
Authors: Huang Pei-Pei  , Liu Da-Gang  , Liu La-Qun  , Wang Hui-Hui  , Xia Meng-Ju  , Chen Ying  ,   School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054, China
Published: December 2020

A single-channel pulsed-power vacuum device is studied. Based on the platform of CHIPIC, the limitation of memory and computation speeds of a single computer is broken through by the method of parallel computation of multi-computers. For the model of the whole device, the models of the parts of feed-in, convergence and transmission in the single-channel pulsed-power device are built, and the parameters are set up. The obtained voltages between the cathode and anode, as well as the currents of the cathode and the anode using the proposed models are in accordance with the theoretical ones. The single-channel pulsed-power vacuum device also can retain magnetically insulated and achieve the function of convergence of power. This shows the feasibility of the single-channel pulsed-power vacuum device.
First-principles study on the electronic and optical properties of the (Eu,N)-codoped anatase TiO2 photocatalyst
Authors: Liu Fang  , Jiang Zhen-Yi  ,   Institute of Modern Physics, Northwest University, Xi’an 710069, China;,   Department of Physics and Electronics, Shanxi Datong University, Datong 037009, China
Published: December 2020

We have calculated the electronic and optical properties of Eu-doped, N-doped, and (Eu,N)-codoped TiO2 using plane-wave pseudopotential method based on the density functional theory. The calculated results show that there are impurity levels of Eu 4f appearing in the band gap of Eu-doped system, and N-doped system can lead to narrowing of the band gap. Moreover, the synergistic effect of the Eu and N codoped TiO2 leads to the lattice distortion and band gap narrowing. Optical absorption curves indicate that the (Eu,N)-codoped system exhibits a significant red-shift of absorption edge, which enhances the visible-light photocatalytic activity.
Phase sensitivity of rotation sensing in coupled resonator waveguides
Authors: Tian He  , Sun Wei-Min  , Zhang Yun-Dong  ,   Key Lab of In-fiber Integrated Optics, Ministry Education of China, Science of College, Harbin Engineering University, Harbin 150001, China;,   Institute of Opto-Electronics and National Key Laboratory of Tunable Laser Technology, Harbin Institute of Technology, Harbin 150080, China
Published: December 2020

The dispersion of optical resonator structures can be used to increase the sensitivity of rotation sensing. Using coupled resonator waveguides can realize strong dispersion. In this paper, the transfer matrix method is used to analyze the phase sensitivity of rotation sensing in coupled resonator waveguides, and investigate the influences of resonator arrangement and waveguide parameters on the phase sensitivity. Results show that phase curves and phase sensitivity are dependent on resonator arrangement. The number of resonator and coupling coefficients can influence not only the number and bandwidths of peaks for phase sensitivity of rotation sensing but also the variation of phase sensitivity. However, loss can reduce the phase sensitivity. The results can be used to design the phase sensitivity of coupled resonator waveguides using the resonator arrangement and waveguide parameters, and are beneficial for applications of coupled resonator waveguides in rotation sensing.
Study on scattering properties of the metal wire gating in a THz band based on Green function method
Authors: Zhang Hui-Yun  , Liu Meng  , Yin Yi-Heng  , Wu Zhi-Xin  , Shen Duan-Long  , Zhang Yu-Ping  ,   Qingdao Key Laboratory of Terahertz Technology, College of Science, Shandong University of Science and Technology, Qingdao 266510, China
Published: December 2020

The present paper utilizes the Green function method to analyze the scattering properties of the metal wire grating in the THz band, and further to study the influence of the diffraction on the transfer characteristic of the metal wire grating. Results prove that the transmission amplitude of the incident electromagnetic wave is increasing monotonously with the enlargement of the value of a/, and it arrives at the maximum in the zero-order diffraction limit. Due to the strengthened effect of diffraction, transmission curves of the incident electromagnetic wave show oscillation in the critical frequency transition region. Due to the diffraction effect, the transmission amplitude of the incident electromagnetic wave demonstrates an overall decline in the diffraction zone, and it is decreasing monotonously with the enlargement in the value of a/. Compared with microwave transmission line method, this method can aliminate the restriction that the wavelength of the incident electromagnetic wave must be greater than the wire grating constant, and the thickness of wire grating must be far less than the metal line width. This method could be used to analyze the distribution of the electromagnetic properties of the system accurately; and it will be a generally suitable one.
Study on complete photonic band gaps of two-dimensional air annular photonic crystals
Authors: Liu Hui  , Liu Dan  , Zhao Heng  , Gao Yi-Hua  ,   School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, China;,   School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China;,   Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, China
Published: December 2020

Plane wave expansion method was employed to study the complete photonic band gap (PBG) of two-dimensional air annular photonic crystals (PCs). Comparison of the complete PBG of the air annular photonic crystal and the commonly used PCs (square-and triangular-lattice dielectric rods in air and square-and triangular-lattice air holes in dielectric background) reveals that a larger complete PBG can be obtained for the air annular PCs. Furthermore, the complete PBG is observed for the air annular PCs even if the dielectric contrast is low, while it is difficult to achieve a complete PBG for the commonly used PCs. For example, for the square and triangular lattice air-hole PCs, the complete PBG is observed when the refractive index of the dielectric materials is arger than 2.8 and 3.2, respectively. But the complete PBG can be observed when the refractive index is arger than 2 for the air annular PCs.
Curvature sensor based on side-leakage photonic crystal fiber with high sensitivity and broad linear measurement range
Authors: Lou Shu-Qin  , Wang Xin  , Yin Guo-Lu  , Han Bo-Lin  ,   School of electronic and information engineer, Beijing Jiaotong University, Beijing 100044, China
Published: December 2020

Based on Sagnac interferometer by incorporating a segment of side-leakage photonic crystal fiber (SLPCF), a curvature sensor with high sensitivity and broad linear measurement range was proposed and demonstrated experimentally. Experimental results show that high sensitivity to curvature can be achieved by measuring group modal birefringence and wavelength shift of transmission dip when the linear side-leakage defect is in the same direction as the bending, but the linear measuring range is not large enough to cover the small curvature. When the linear side-leakage defect is in the vertical direction to the bending, the sensitivity can be as high as 10.798 nm·m-1 and the linear measurement range as wide as 0–5.03 m-1 by measuring wavelength shift of transmission. Combined with the introduction of the measurement matrix, the measurement of temperature and curvature can be realized simultaneously, which would offer a way to eliminate the perturbation of the environment temperature to the measurement values of the curvature. Under the same conditions, though the sensitivity obtained by measuring group modal birefringence is low, it can be regarded as a curvature sensor which is insensitive to temperature.
Design of a high-speed silicon electro-optical modulator based on an add-drop micro-ring resonator
Authors: Cao Tong-Tong  , Zhang Li-Bin  , Fei Yong-Hao  , Cao Yan-Mei  , Lei Xun  , Chen Shao-Wu  ,   State Key Laboratory on Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
Published: December 2020

Silicon electro-optical modulators based on add-drop micro-ring resonators have the advantage of more freedom in designing high-extinction-ratio and large-bandwidth modulators without changing the ion doping processes of the chip. Here we design a high-speed silicon modulator based on an add-drop micro-ring resonator with a radius of 20 m; it demonstrates high extinction ratio with low reverse bias. How the coupling between the straight waveguide and the ring resonator affects the performances is studied theoretically and it is found that a lower coupling coefficient at drop port leads to a higher extinction ratio but not the best bandwidth. Therefore, a balance should be considered between extinction ratio and bandwidth. According to the optimized result of the parameters the device is fabricated and tested. The spectrum testing indicates that the device can have 12 dB extinction ratio when it is operated at 3 V reverse bias. Furthermore, we have observed 8 Gbps open-eye diagram with only 1.2 V peak-to-peak signal voltage.
Experiments on vortex dipoles generated by a submerged round jet
Authors: Chen Ke  , You Yun-Xiang  , Hu Tian-Qun  ,   State Key Laboratory of Ocean Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
Published: December 2020

The formation mechanism and evolution characteristics of a submerged round jet in a uniform fluid of finite depth are investigated experimentally. A spillover system is designed to produce a continuous horizontal jet in the background fluid with a constant velocity, and the flow is visualized by the dyed liquid. Experiments are conducted under different combinations of Reynolds number Re, confinement number C and nondimensional draft d/H, where d is the vertical distance from the jet to the free surface, and H is the depth of the ambient fluid. Four flow patterns are identified for various C. When C1, the jet shows a deep-water pattern, while for 1 C2, it shows the transitional pattern, the jets do not develop a structured flow for the two jet patterns. When 2 C10, the jet shows the shallow-water pattern, while if C10, the jet shows the extreme-shallow-water pattern. In both these two patterns, the jets generate vortex dipole structures. In the extreme-shallow water pattern, the nondimensional vortex formation time tf* for the vortex dipole structure is proportional to the nondimensional injection time Tinj* for various draft d/H. In the shallow-water pattern, tf* depends linearly on Tinj*Re1/2 when the draft d/H=0.5; however, there is no observable relationships between tf* and Tinj* for other draft d/H.
Ring deposition of drying suspension droplets
Authors: Zhang Wen-Bin  , Liao Long-Guang  , Yu Tong-Xu  , Ji Ai-Ling  ,   Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
Published: December 2020

Deposition of colloidal particles in a drying droplet is important in many scientific researches and technological applications. In this work, the ring deposition of drying droplets on a solid substrate is investigated experimentally at a microscopic level. A ring deposition is formed at the contact line as the water solution droplet containing SiO2 particles is drying, just like the formation of coffee ring. Contact line pinning is crucial to the ring deposition formation. There will be a replenish flow in the droplet towards the edge, and the particles are driven to the contact line, deposited on the substrate. As the particle mass fraction is large, the particles which are left inside the spot, when the droplet dries out, may form a single particle layer, packing in order. The contact angle of the droplet on glass substrate is very small, the SiO2 particles will gather at the rim of the droplet, which initially form a chain along the contact line. As more particles come to the rim, they are deposited in a line by line way to form a 2D close packing. Since the contact angle decreases with evaporation when the contact line is pinned, a capillary force between liquid surface and particles arises once the height of droplet surface near the contact line is lower than that of the particle, pushing the particles to move inward. The effect on the larger particles is more pronounced-it even leads to a separation of the particles, with the smaller ones at the outer side.
Study on ionization damage of silicon-germanium heterojunction bipolar transistors at various dose rates
Authors: Sun Ya-Bin  , Fu Jun  , Xu Jun  , Wang Yu-Dong  , Zhou Wei  , Zhang Wei  , Cui Jie  , Li Gao-Qing  , Liu Zhi-Hong  ,   Institute of Microelectronics, Tsinghua University, Beijing 100084, China;,   Tsinghua National Laboratory for Information Science and Technology, Beijing 100084, China
Published: December 2020

Ionizing radiation effects in silicon-germanium (SiGe) heterojunction bipolar transistors (HBTs) at different dose rates were investigated. Experimental results show that the base current increases with increasing accumulated dose for the high and low dose rates of irradiation, causing a significant drop in current gain. Besides, the lower the dose rate, the higher the radiation damage, which demonstrates a significantly enhanced low-date-rate sensitivity (ELDRS) effect in the SiGe HBTs. The different degradation behaviors for high and low dose rates of irradiation are compared with each other and discussed; furthermore, the underlying physical mechanisms are analyzed and investigated in detail.
Influence of pulse tapping technology on surface roughness of polyimide capsule
Authors: Cao Hong  , Huang Yong  , Chen Su-Fen  , Zhang Zhan-Wen  , Wei Jian-Jun  ,   Research Centre of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900, China;,   Institute of Atomic and Molecuar Physics, Sichuan University, Chengdu 610065, China
Published: December 2020

As one of the most important ignition capsules, the polyimide capsule was prepared by depolymerizable mandrels technique combined with vapor deposition polymerization method. Instead of the plane pan and piezoelectric vibration model, the mesh pan and pulse tapping was selected to reduce microsphere collision so that surface quality was improved in polyimide fabrication. Experimentsal and theoretical results show that the capsule surface becomes more rough because of collisions between microspheres and the pan. The mesh pan could reduce microsphere collisions, which was also reduced by changing piezoelectric vibration into pulse tapping. As a result, root-mean-square value ranges from 5293 nm to 2844 nm. There are many advantages with pulse tapping model, such as better controllability,lower bounce rate and less static; however piezoelectric vibration model is slightly better than the pulse taping in wall thickness uniformity. Measurements of single microsphere show that the deviation of the former is 0.68 which is better than that of the latter (0.73 m). For the average value of microspheres in the same batch, the former has a value 0.26 which also is better than the latter (0.57 m).
Low frequency noise analysis and resistance relaxation in Au/SrTiO3/Au for bipolar resistive switching
Authors: Wang Ai-Di  , Liu Zi-Yu  , Zhang Pei-Jian  , Meng Yang  , Li Dong  , Zhao Hong-Wu  ,   Beijing General Research Institute of Mining and Metallurgy, Beijing 100160, China;,   BGRIMM Advanced Materials Science &Technology Co., Ltd, Beijing 102206, China;,   Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
Published: December 2020

The resistance relaxation in Au/SrTiO3/Au sandwiches with bipolar resistance switching has been investigated by the low frequency analysis. The power spectral density of the conducting current fluctuation in the high resistance state and the low resistance state shows 1/f behaviors. By contrast experiment, the low frequency noise for the high resistance state is ascribed to the Schottky barrier under reverse bias and the oxygen vacancy diffusion, while the noise in the low resistance state is due to the carriers fluctuation arising from the oxygen vacancy migration. The resistance relaxation can be further understood as the diffusion of oxygen vacancies under an electric field.
Study on the properties and optical emission spectroscopy of the intrinsic silicon thin film in silicon heterojunction solar cells
Authors: Xue Yuan  , Gao Chao-Jun  , Gu Jin-Hua  , Feng Ya-Yang  , Yang Shi-E  , Lu Jing-Xiao  , Huang Qiang  , Feng Zhi-Qiang  ,   Key Laboratory of Materials Physics of Ministry of Education, School of Physical Engineering, Zhengzhou University, Zhengzhou 450052, China;,   School of Physical Engineering, Zhengzhou University, Zhengzhou 450052, China;,   State Key Laboratory of PV Science and Technology, Trina Solar Energy Co. Ltd, Changzhou 213031, China
Published: December 2020

The intrinsic silicon thin film for passivation of the crystalline silicon wafer surfaces in silicon heterojunction cells was prepared by very high fregucency plasma enhanced CVD (VHF-PECVD). Plasma emission versus time was recorded by optical emission spectroscopy (OES) during the silicon thin film deposition. Results show that the Hα* and SiH* signals stabilize soon (about 25 s after deposition) under the optimized deposition conditions, and the variation of SiH*/Hα* ratio is little, thus avoiding the structure non-uniformity of silicon film during the growth. The reason is that the SiH4 back diffusion is avoided owing to SiH4 being not fully depleted. The study of the influence of the deposition parameters on steady-state plasma emission spectra and properties of silicon films shows that as the SiH4 concentration increases, the Hα* decreases and the SiH* increases, the silicon film will transit from microcrystalline to amorphous, and the good passivation effect can be achieved in the amorphous silicon film. Hα* and SiH* increase firstly and then decrease with the deposition pressure, the decrease of Hα* and SiH* under high pressure can be attributed to a high polymer formation which is not beneficial to the formation of high quality silicon film, and therefore the passivation effect of silicon films decreases under high pressures. Hα* and SiH* increase with power density, and are saturated when the power density is 150 mW/cm2; for this the quality and passivation effect of the silicon film begin to decrease, the passivation effect of the silicon film at a power density of 50 mW/cm2 is poor, which may be due to the low concentration of atomic H being unable to fully passivate the dangling bonds at the silicon surface.
Potassium diffusive coupling-induced the variation of spiral wave in cardiac tissues
Authors: Qiao Cheng-Gong  , Wang Li-Li  , Li Wei-Heng  , Tang Guo-Ning  ,   College of Physical science and Technology, Guangxi Normal University, Guilin 541004, China
Published: December 2020

In some cases, the extracellular concentration of potassium ions cannot be regarded as being constant. The potassium lateral diffusion leads to extracellular accumulation of potassium ions and the generation of potassium diffusive coupling. The effect of potassium diffusive coupling on spiral wave is investigated by using the Luo-Rudy phase I cardiac model with potassium diffusive coupling. The numerical results show that when the strength of potassium diffusive coupling is relatively strong, the potassium diffusive coupling makes extracellular potassium ion concentration rise first and then regularly oscillate, leading to the irregular meandering of spiral wave. It is observed that the width of spiral arm and the frequency of spiral wave decrease as the strength of potassium diffusive coupling increases. Thus, when the strength of the potassium diffusive coupling is strong enough, the potassium diffusive coupling can eliminate spiral wave and spatiotemporal chaos.
Image reconstruction algorithm based on inexact alternating direction total-variation minimization
Authors: Wang Lin-Yuan  , Zhang Han-Ming  , Cai Ai-Long  , Yan Bin  , Li Lei  , Hu Guo-En  ,   National Digital Switching System Engineering and Technological Research Center, Zhengzhou 450002, China
Published: December 2020

Image reconstruction algorithms implemented in existing computed tomography (CT) scanners require that the projection data should be available in proportional-space. The image reconstruction from the projections viewed from few angles has already been one of the hot problems in the research of iterative reconstruction algorithms. Total variation (TV)-based CT image reconstruction has shown to be experimentally capable of producing accurate reconstructions from sparse-view data. Reconstruction algorithms based on alternating direction method (ADM) show higher performance among these TV-based algorithms. However, computing the pseudoinverse at each iteration is too costly to implement numerically in the exact ADM algorithm. For this problem, then inexact ADM is adopted, which uses linearization and proximal points techniques such that computing the pseudoinverse can be accomplished by fast Fourier transforms. Experimental results demonstrate that the proposed method can accelerate the exact ADM algorithm, with little accuracy loss, and the computing time is approximatively reduced by 30%.
Comprehensive assessment of the accuracy of the data from near space meteorological rocket sounding
Authors: Fan Zhi-Qiang  , Sheng Zheng  , Wan Li  , Shi Han-Qing  , Jiang Yu  ,   Institute of Meteorology and Oceanology, PLA University of Science and Technology, Nanjing 211101, China;,   Unit 620, National Defense Office of Science and Industry Technology of Jiang Xi Province, Nanchang 330000, China
Published: December 2020

We use the data obtained from empirical forecast model and satellite remote sensing to analyze and assess the accuracy of the data obtained from first near space meteorological rocket sounding in Jiuquan Satellite Launch Center (JSLC) in November 2004. Analysis shows that the data of empirical forecast model has great difference from meteorological rocket sounding data for the middle-upper stratosphere. Because the empirical forecast model has low spatial and temporal resolution, especially it lacks of the sounding data for the middle-upper stratosphere in China, the deviation between the data of meteorological rocket and the satellite data is obviouslly lower than the empirical forecast model gave. The deviation is caused by the systematic error between the two and the difference of time, latitude and longitude. Comprehensive comparison results show that the data of meteorological rocket is of high accuracy and credibility compared to the data of the empirical forecast model and satellite remote sensing. These data can be used to specify the probe’s results from other ways.
Chaos control of SEPIC converter based on resonant parametric perturbation method
Authors: Li Guan-Lin  , Li Chun-Yang  , Chen Xi-You  , Zhang Xiao-Wei  ,   Department of Electrical Engineering, Dalian University of Technology, Dalian 116023, China;,   Harbin Electrical Company Limited, Harbin 150040, China
Published: December 2020

Choosing the current of the front inductor of SEPIC converter as controlled object, the resonant parametric perturbation is applied to control the chaos in SEPIC converter. Through the small perturbations of circuit parameter, chaos control of SEPIC converter is realized, and the results are analyzed by the time domain waveform, power spectrum, and bifurcation diagram. Finally, the results of the circuit experiment demonstrate that chaos control of SEPIC converter can be realized by the resonant parametric perturbation method.
A dynamic threshold value control method for chaotic neural networks
Authors: Zhang Xu-Dong  , Zhu Ping  , Xie Xiao-Ping  , He Guo-Guang  ,   Department of Physics, Zhejiang University, Hangzhou 310027, China
Published: December 2020

A dynamic threshold value control method is proposed to get control over a chaotic neural network (CNN). The sinusoidal signal, which constitutes the key component of the brain wave, is taken as the control signal to change the threshold value of the internal states of the CNN. The chaos control of the CNN is therefore reached with its outputs of the controlled CNN reciprocating between a stored pattern and its reverse pattern related with the initial pattern. And then the CNN can be applied in information processing, such as pattern recognitionetc. The chaos control method works in a self-adaption way since it does not need to set the threshold value beforehand, which is in accordance with brains’ thinking activities.
Vehicle negotiation model and bifurcation dynamic characteristics research
Authors: Huang Chen  , Chen Long  , Bi Qin-Sheng  , Jiang Hao-Bin  ,   College of Civil Engineering of Jiangsu University, Zhenjiang 212013, China;,   College of Civil Engineering of Jiangsu University, Zhenjiang 212013, China
Published: December 2020

There are three kinds of conflicts in a traffic flow at the traffic circle because of track changing. We establish the driver model by regarding each vehicle as an intelligent agent which constitutes the multi-agent system by integrating the cellular automation model at the traffic circle. Besides, we put forward the problem how to eliminate the conflicts between the vehicle agents by priority strategy and dynamic negotiation mechanism. Take the traffic flow at the classic traffic circle of the suburban area of a small-medium city as the sample data to simulate and verify the accuracy of the model, and study the influences of some factors on the flow of motor vehicle, such as the proportion of different driver type and track changing probability, etc. The experimental result shows that the model constructed is consistent with the actual situation. Meanwhile, it is found that the driver characteristics have obvious influences on the flow, and the track changing probability follows, which does not have obvious influences on the fluctuation in the flow.
Study on P-branch emission spectral lines of AuO molecule using improved analytical formula
Authors: Jiang Yong-Hong  , Sun Wei-Guo  , Zhang Yi  , Fu Jia  , Fan Qun-Chao  , Li Hui-Dong  , Feng Hao  ,   Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, China;,   School of Physics and Chemistry, Research Center for Advanced Computation, Xihua University, Chengdu 610039, China;,   School of Physics, Sichuan University, Chengdu 610065, China
Published: December 2020

An analytical formula has been proposed to predict the high-lying spectral lines of rovibrational transitions for diatomic systems by Sun et al. who used multiple spectral difference method. This study improves the formula based on their previous work by adding a higher order spectral term Hv. Applications of this new formula to the AuO molecule shows that the accuracy of the P-branch rovibrational transition lines is about one order of magnitude better than the results obtained using the previous formula, and that the contributions of the small quantity Hv to the high-lying rovibrational energies and the transitional lines are shown to be important.
Study on the relationship between the population of metastable state and time delay in an erbium-doped optical fiber
Authors: Qiu Wei  , Gao Bo  , Lin Peng  , Zhou Jing-Ting  , Li Jia  , Jiang Qiu-Li  , Lü Pin  , Ma Ying-Chi  ,   Department of Physics, Liaoning University, Shenyang 110036, China;,   Key Laboratory of Cryogenics, TIPC, CAS, Beijing 100190, China
Published: December 2020

The slow light propagation in optical fiber has attracted much attention because of its practical applications. Use of coherent population oscillation to produce slow light propagation has many advantages over other methods. We investigate the reduction of the group velocity propagation by the coherent population oscillation in erbium-doped optical fiber, and also the relationship between the population of metastable state and the time delay by changing the doping concentration, the length of the fiber, the input power, and the pump power. The results show that we can select a high doping concentration of erbium in the fiber, increase the length of the fiber, decrease the pump power and select the appropriate power of the signal light to increases the time delay.
Influence of electrolytes on diffusion properties of colloidal particles in dense suspensions
Authors: Zhong Cheng  , Chen Zhi-Quan  , Yang Wei-Guo  , Xia Hui  ,   School of Physics and Electronic, Central South University, Changsha 410083, China;,   School of Business, Hunan City University, Yiyang 413000, China
Published: December 2020

The influence of electrolytes on the diffusion properties of polystyrene colloidal particles in dense suspensions is measured by means of phase-modulated fiber optic low-coherence dynamic light scattering. In our experiments, both NaCl and BaCl2 are used as electrolytes. Experiment results show that the diffusion coefficients of the polystyrene colloidal particles increase with the increasing of ion concentration and ion valence when the concentration of electrolyte is below 0.01mol/L and the temperature keeps constant. The diffusion coefficients obtained experimentally show good agreement with the diffusion coefficients obtained by using the Stern model.
Density-density correlation in quasi two-dimensional free expanding Bose-Einstein condensates
Authors: Xu Yan  , Fan Wei  , Chen Bing  , Nan Xiang-Hong  , Chen Da  , Zhou Qiang  , Zhang Lu-Yin  ,   College of Science, Shandong University of Science & Technology, Qingdao 266510, China
Published: December 2020

The effective Lagrangian density function and the quantum fluctuation of the wave function in the form of quantized operators are presented for a quasi two-dimensional Bose-Einstein condensate by means of Madelung transformation. This paper calculates the two-point density-density correlation function of the condensate during its free expansion after its confinement potential is removed. Results show that the two-point density-density correlation function in the long-wave limit is proportional to the wave number k and it tends to be a constant in the short-wave limit.
Phase field crystal study on grain boundary evolution and its micro-mechanism under various symmetry
Authors: Long Jian  , Wang Zhao-Yu  , Zhao Yu-Long  , Long Qing-Hua  , Yang Tao  , Chen Zheng  ,   State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072, China
Published: December 2020

Phase field crystal method is used to investigate the deformation process and mechanism of twined structure of a trigonal phase under uniaxial tensile deformation, and the evolution and corresponding micro-mechanism of low-angle symmetric and asymmetric grain boundaries (GB) as well as high-angle symmetric and asymmetric GB during deformation process are analyzed in detail. The deformation is performed under the condition that the direction of applied stress is parallel to that of initial GB. Results show that low-angle symmetric GB is composed of two kinds of edge dislocations with the angle made by Burgers vectors being around 60 During deformation, two kinds of dislocations in low-angle symmetric GB move along two opposite directions, then meet with the same kind of dislocation emitted from another GB leading to the annihilation of partial dislocations. As to the low-angle asymmetric GB, its only one kind of dislocation first climbs and moves along the horizontal direction of the applied stress, then each dislocation will break down into two dislocations with their Burgers vectors making an angle about 120, finally a perfect single crystal is formed via the movement and annihilation of dislocations. High-angle GBs first keep horizontal shape under the applied stress, then become serrated, and the dislocations are emitted from the cusps in GBs. Finally, the high-angle asymmetric GB will decompose with the movement and annihilation of dislocation, while the shape of high-angle symmetric GB becomes horizontal again. It can be seen that the high-angle symmetric GB is more stable than the high-angle asymmetric GB; this is in agreement with the results of experiments and molecular dynamics.
Study on control pulse combination of pulse train controlled switching converter and its multi-periodicity analysis
Authors: Sha Jin  , Xu Jian-Ping  ,   Key Laboratory of Magnetic Suspension Technology and Maglev Vehicle, Ministry of Education, School of Electrical Engineering, Southwest Jiaotong University, Chengdu 610031, China
Published: December 2020

Pulse train control technique is realized through the output voltage regulation of switching dc-dc converter by adjusting the control pulse combination of high-power and low-power control pulses in a control pulse repetition cycle. Once the circuit parameters are determined, the control pulse combination is fixed. The control pulse combination directly affects the steady-state performances of pulse train (PT) controller. In this paper, the control pulse combination of PT control technique is studied by using the continued fraction technique. A one-dimensional normal form of discrete-time map of PT controlled buck converter operating in discontinuous conduction mode is also established in which the steady state performances, such as parameter evaluation of multi-periodicities and output voltage ripple of PT controlled DCM buck converter, are analyzed. The simulation result, experimental result, and the results in the literature are in accordance with the theoretical analysis. This investigation is helpful to obtain a deeper understanding of PT control technique.
Dynamical modeling and multi-period behavior analysis of voltage-mode bi-frequency controlled switching converter
Authors: Wu Song-Rong  , He Sheng-Zhong  , Xu Jian-Ping  , Zhou Guo-Hua  , Wang Jin-Ping  ,   Key Laboratory of Magnetic Suspension Technology and Maglev Vehicle, Ministry of Education, School of Electrical Engineering, Southwest Jiaotong University, Chengdu 610031, China;,   School of Electrical Engineering and Automation, Hefei University of Technology, Hefei 230009, China
Published: December 2020

A dynamical model is proposed and the corresponding characteristic aligns are derived for voltage-mode bi-frequency controlled switching converter operating in discontinuous conduction mode. According to the dynamical model, the border-collision bifurcation and multi-period behaviors, such as period-2, period-3, period-4, and so on, are studied using bifurcation diagrams as the circuit parameters are varied. It is found that the converter behaves along the bifurcation route of period-1, multi-period, and period-1, and the change of period state is induced by border-collision bifurcation. Based on the characteristic equation, the converter stability is investigated by the Lyapunov exponent. It is shown that Lyapunov exponent is always smaller than zero with the variation of circuit parameters and the converter operates in stable period state all the time. Also, it is validated that period-3 behavior of voltage-mode bi-frequency controlled switching converter does not predicate its inevitable chaos. Time-domain waveforms, phase portraits, and frequency spectra of voltage-mode bi-frequency controlled switching converter are analyzed by circuit simulation, which validates the feasibility of dynamical model and the correctness of theoretical analysis. Simulation results are verified by experiments in this paper.
The base scale entropy analysis of fMRI
Authors: Liu Tie-Bing  , Yao Wen-Po  , Ning Xin-Bao  , Ni Huang-Jing  , Wang Jun  ,   Nanjing General Hospital of Nanjing Military Command, Nanjing 210002, China;,   Key Laboratory of Modern Acoustics and Department of Electronic Science and Engineering, Institute for Biomedical Electronic Engineering, Nanjing University, Nanjing 210093, China;,   Image Processing and Image Communications Key Lab., Nanjing Univ. of Posts & Telecomm., Nanjing 210003, China
Published: December 2020

The complexity of human brain activity has shown a certain law associated with the difference of age and sex, which can be identified by fMRI (functional magnetic resonance imaging). In this paper, we apply the base scale entropy to 54 groups’ fMRI data of different ages and gender, and then distinguish the different groups through the entropy. Through the base scale entropy with reasonable parameters, fMRI of different people could be distinguished effectively, which provides convenience to further data analysis. Results show that the base scale entropy between men and women of the same age has some differences and the entropy changes correspondingly with the change of age. In order to distinguish different people of different ages, we need to adjust the scale parameter to adapt to the trends in age changes. The fMRI data analysis shows that the base scale entropy could distinguish different populations’ fMRI data characteristics for further facilitating the analysis of complex signals.
Well layer design for 1eV absorption band edge of GaInAs/GaNAs super-lattice solar cell
Authors: Wang Hai-Xiao  , Zheng Xin-He  , Wu Yuan-Yuan  , Gan Xing-Yuan  , Wang Nai-Ming  , Yang Hui  ,   Laboratory of Nanodevices and Applications, Suzhou Institute of Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, China;,   University of Chinese Academy of Sciences, Beijing 100080, China
Published: December 2020

The GaInAs/GaNAs super-lattice with a feature of space separation of In and N constituents as an active region, is one of the most important ways to achieve 1 eV GaInNAs-based solar cells. To experimentally realize the high-quality super-lattice structure with the required band-gap, Kronig-Penney model is used to obtain the barrier thickness dependence on the well thickness and its composition. Meanwhile, the strain state of GaInAs/GaNAs SLs with various well choices is also discussed. Results show that when both the GaNAs and GaInAs act as the well layers the super-lattice can achieve 1 eV band-gap, and when the GaN0.04As0.96 is considered to act as the well layer, the entire GaInAs/GaNAs SLs have smaller strain accumulations as compared with the case of Ga0.7In0.3As as the well layer in the super-lattice structure.
Properties of entanglement in one-dimensional Ising model with a tilted magnetic field
Authors: Wang Qi  , Wang Xiao-Qian  ,   School of Science, Changchun University of Science and Technology, Changchun 130022, China
Published: December 2020

We study the entanglement properties in a one-dimensional Ising chain with a tilted magnetic field that is capable of showing both integrable and nonintegrable behaviors. Here the pairwise entanglement is characterized by concurrence and the multipartite entanglement is characterized by the Q measure. According to the entanglement properties of the ground state in the Ising mode, which have tilt angle, we can find that the Q measure decreases with the increasing of the strength of external field. And the phase transition property of the system is changed with the increase of tilt angle for the external magnetic field. We also consider the evolution of entanglement in this model, and find that the nonintegrability can suppress the pairwise entanglement but promotes the multipartite entanglement with the integrable system.
Complex Turing patterns in two-layer non-linearly coupling reaction diffusion systems
Authors: Li Xin-Zheng  , Bai Zhan-Guo  , Li Yan  , Zhao Kun  , He Ya-Feng  ,   College of Sciences, Hebei University of Science and Technology, Shijiazhuang 050018, China;,   College of Physics Science and Technology, Hebei University, Baoding 071002, China
Published: December 2020

The influence of Turing modes in two subsystems on pattern formation is investigated by the two-layer non-linearly coupled Brusselator model. It is found that the coupling coefficient and wave number ratio between two Turing modes take an important role in the pattern formation and pattern selection. The kind of pattern changes from simple pattern to complex one with the increase of wave number ratio. When nonlinear coupling coefficient is smaller than 0.1, the short wave mode in system 1 under the action of instability mode in system 2 can form not only simple pattern (such as simple hexagon and quadrilateral and stripe pattern), but also complex pattern due to the resonance coupling between the two Turing modes (such as honeycomb hexagon and super hexagon and complex black-eye pattern), and the transformation process of pattern from quadrilateral to superlattice pattern is observed for the first time under the specific parameters. When nonlinear coupling coefficient is more than 0.1, the simple patterns such as simple hexagon and stripe pattern are obtained only in system 1, because there is no resonance coupling between the two Turing modes in system 1.
Effect of ion channel random blocking on the spatiotemporal dynamics of neuronal network
Authors: Wang Rong  , Wu Ying  , Liu Shao-Bao  ,   State Key Laboratory for Strength and Vibration of Mechanical Structure, School of Aerospace, Xi’an Jiaotong University, Xi’an 710049, China
Published: December 2020

Ion channels in the membrane of neuron can be blocked by some toxic chemicals. Blocking ion channels will reduce the conductivity and the number of activated channels, and affect the electrical activity of neurons. And then the spatiotemporal patterns of neuronal network would be changed. In this paper, the nearest-neighbor coupled Hodgkin-Huxley neuronal network with periodic boundary is adapted to the investigation of the evolution of spatiotemporal patterns of neuronal network when the sodium and potassium ion channels are blocked randomly, by using numerical method. The results indicate that sodium ion and potassium ion channel random blockage could lead to the breakup of spiral wave. Furthermore, we analyze the firing probability of neuronal network and find that sodium ion channel random blockage reduces the excitability of neuronal network, which is sensitive to noise; but potassium ion channel random blockage enhances the excitability of neuronal network. Compared with uniform blockage of ion channels, the random blockage of ion channels makes neuronal network have rich dynamics phenomena. Finally, the no-flux boundary condition is applied and the results are similar to the above ones.
A weighted scale-free network model with high clustering and its synchronizability
Authors: Wang Dan  , Hao Bin-Bin  ,   Key Laboratory of Manufacturing Industrial Integrated Automation, Shenyang University, Shenyang 110044, China
Published: December 2020

The detecting of clusters or communities in large real-world networks such as large social or information networks is of considerable significance. We propose a new weighted evolving model of high clustering scale-free network incorporating a community structure mechanism, which means the addition of the new node depends on not only a single node but also a community. In the process of the evolution, a new node with probability p and a new community with the probability 1–p are added to the network. Different from the existing studies where new links are additionally established, some links with probability φ according to the triad formation mechanism and other links with the probability 1–φ according to the random selection mechanism are connected between neighbors in the model. The topology and weights of links of the network evolve as time goes on. Moreover, the evolving model gives power-law distributions of degree, weight, and strength as confirmed in several real world systems. Especially, the average clustering coefficient exhibits power-law decay as a function of degree of node. Both the community structure and the triad formation can enhance the average clustering coefficient of scale-free networks. Furthermore, we investigate how the synchronization of the network is influenced by the evolution mechanism of the network. Numerical simulation results show that the network synchronizability is optimized when the average clustering coefficient decreases in the model.
Study of nuclear stopping in Au+Au collisions at alternating gradient synchrotron energies by the ultra-relativistic quantum molecular dynamic model
Authors: Yuan Ying  ,   College of Physics and Electronic Engineering, Guangxi Teachers Education University, Nanning 530023, China
Published: December 2020

Nuclear stopping in Au+Au collisions at alternating gradient synchrotron energies is studied in the framework of the modified ultra-relativistic quantum molecular dynamics transport model, in which mean field potentials of both formed and “preformed” hadrons (from string fragmentation), medium-modified nucleon-nucleon elastic cross sections, and cluster recognition criteria are considered. It is found that nuclear stopping is influenced by both the mean field potentials of formed and “preformed” hadrons and the medium modification of nucleon-nucleon elastic cross section. The free proton number is higher than that from the experimental rapidity distribution in the central region of rapidity distribution, which can be understood by considering the new criteria of judging fragments.
Establishment of persistent fission chains in a super prompt critical system
Authors: Gao Hui  , Xie Qi-Lin  , Liu Xiao-Bo  , Huang Po  , Song Ling-Li  , Liang Wen-Feng  , Fan Xiao-Qiang  ,   Key Laboratory of Neutron Physics of China Academy of Engineering Physics, Mianyang 621900, China;,   Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

Through using the basic probability theory and establishing the law of finite chains near the prompt criticality, we deduce the formula of relation between the neutrons number and time in the process of persistent chains initiated by a single-pulse neutron source in burst reaction. The formula is validated by the experiments of CFBR-Ⅱ. The formula is the development of Hansen theory model because it can describe not only the developing tendency in the later stages but also the rapid increasing of neutron number in the early stage. Furthermore, according to the relation between the initial time of burst reaction and the intensity of neutron source, we illustrate that the initial time is hardly dependent on the intensity of weak neutron source.