bluuebunny/crossref_metadata_2025 huggingface dataset:
A novel dual-band left-handed metamaterials composed of multi-defects hexagonal structure
Authors: Yang Huai  , Wang Chun-Hua  , Guo Xiao-Rong  ,   College of Information Science and Engineering, Hunan University, Changsha 410082, China
Published: December 2020

This paper presents a novel dual-band magnetic resonance with multi-defect hexagonal structure. Staggered defects double hexagonal metal rings was put on a microwave substrate. So the coupling capacity of the two rings was damaged. Then the dual-band magnetic resonance has been obtained. The traditional structure of dual-band is very complicated. But the new structure is simple and the size is also very easy to control. Finally, we combined the novel structure with metal wires to make dual-band left-handed metamaterials. From the result of the HFSS simulation, this left-handed metamaterials has obtained dual-band at 6.5–7.0 GHz and 8.8–9.3 GHz. The dual-band left-handed structure has a great influence on the microwave filter, antenna, and other microwave devices.
Generation of two-mode photon-atom quadrature squeezing based on enhanced raman scattering
Authors: Shao Hui-Li  , Li Dong  , Yan Xue  , Chen Li-Qing  , Yuan Chun-Hua  ,   Department of Physics, East China Normal University, Shanghai 200241, China;,   Department of Physics, Fundamental School, Shanghai University of Engineering and Science, Shanghai 201620, China
Published: December 2020

Enhanced Raman scattering can be obtained by the initially prepared atomic spin excitation, or by injecting a seeded light field which is correlated with the initially prepared atomic spin excitation. This paper theoretically calculated the quantum fluctuations of the quadrature components of the two-mode photon-atom quantum interface and found that the enhanced Raman scattering based on coherence can improve the initial photon-atom squeezing slightly in a certain scope, and correlation-enhanced Raman scattering can produce strong two-mode squeezing of photon-atom. Such a strong two-mode squeezed state at the photon-atom interface has very important applications in precision measurement research based on the light field and atomic system.
Numerical analysis of in-phase supermode selection of seven-core photonic crystal fiber by gain distribution
Authors: Huang Li-Li  , Fang Xiao-Hui  , Cui Yuan-Ling  , Hu Ming-Lie  , Wang Qing-Yue  ,   Key Laboratory of Opto-electronic Information Science and Technology of Ministry of Education, College of Precision Instruments and Opto-electronics Engineering, Tianjin University, Tianjin 300072, China;,   College of Applied Sciences, Beijing University of Technology, Beijing 100124, China
Published: December 2020

A model based on propagation-rate equations by considering the multi-transverse mode is constructed to describe the amplifier made from seven-core photonic crystal fibers. The output power of the seven eigenmodes in the amplifier infected by the dopant distribution, coupling coefficient and the pump power is discussed using the split-step Fourier algorithm. Mode selection can be realized by the design of dopant distribution and suitable coupling coefficient without the need of other devices. Mode selection may become more convenient due to this method. Moreover, high pump power can contribute to the improvement of the in-phase supermode. These results are helpful for improving the light quality of the amplifier.
Experimental study on backscattering characteristics of sodium beacon based on a long pulse laser
Authors: Wang Feng  , Chen Tian-Jiang  , Luo Zhong-Xiang  , Lu Yan-Hua  , Wan Min  , Peng Bo  , Yin Xin-Qi  ,   Institute of Applied Electronics, CAEP, Mianyang 621900, China
Published: December 2020

A sodium beacon with bright magnitude can be obtained during backscattering time, by utilizing a long pulse laser with parameters matched with a sending and receiving beacon system. This is helpful to get high SNR in detecting beacon, and to achieve a closed-loop correction at high frequency. Based on a 450 mm telescope and a high-energy long pulse laser, the detection experiment of sodium beacon was carried out, and the backscattering characteristics of sodium beacon were obtained. The intensity data of backscattering light with different launching energy and polarization were collected by CCD and PMT. As high as ～15,000 photons/m2·pulse-1 of backscattering light was detected, and the brightness is close to 4.1 magnitudes during backscattering time. The column density in experiment was derived from analyzing and calculating experimental data. No saturation phenomenon was observed during the whole experimental process. And the feasibility to avoid saturation is verified and a bright sodium beacon is obtained by utilizing a long pulse laser.
Design and performance of mid-IR dispersion in photonic crystal fiber prepared from a flattened chalcogenide glass
Authors: Yang Pei-Long  , Dai Shi-Xun  , Yi Chang-Shen  , Zhang Pei-Qing  , Wang Xun-Si  , Wu Yue-Hao  , Xu Yin-Sheng  , Lin Chang-Gui  ,   Laboratory of Infrared Materials and Devices, College of Information Science and Engineering, Ninbo University, Ningbo 315211, China
Published: December 2020

In this paper, using the self-made Ge20Sb15Se65 chalcogenide glass as matrix material, we design an infrared octagon dispersion flattened photonic crystal fiber, and the mid-IR dispersion and transmission characteristics are numerically studied using the multipole method. Results show that when we control the duty ratio (d/Λ) in 0.323–0.367, the dispersion and transmission properties in the 3–5 μm range are adjustable. When we set the hole spacing Λ=3.4 μm, hole diameter d=1.1 μm, in the 4.1–4.9 μm band, the fiber dispersion fluctuates between-0.8 ps·nm-1·km-1 and 0.8 ps·nm-1·km-1, and shows single-mode transmission, low loss (LossAeff2) characteristics, thus it is suitable for nonlinear applications in mid-IR band.
Study on pulse coupler of optical waveguide
Authors: Zhou Jian-Zhong  , Chen Bao-Xue  , Li Jia-Wei  , Wang Guan-De  , Hiromi Hamanaka  ,   School of Optical-Electrical and Computer Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China;,   Shanghai Electric Cable Research Institute, Shanghai 200093, China;,   Engineering research center of optical instruments and systems, Ministry of Education, Shanghai 200093, China;,   Shanghai key laboratory of modern optical system, Shanghai 200093, China;,   Faculty of Engineering, Hosei University, Tokyo 184-8584, Japan
Published: December 2020

A new pulse-coupled device composed of optical waveguide is presented. Its operating mechanism is discussed based on experimental results. Particle nature of light in optical stopping and wave nature of light in mode coupling of branch waveguide are combined in the device operating, then the optical pulse-coupled dynamics between input electrical pulses and synchronous output electrical pulses is realized.
Inner structure of granular pile during its quasi-static avalanches and slow flows
Authors: Pan Bei-Cheng  , Shi Qing-Fan  , Sun Gang  ,   Beijing Institute of Technonlogy, Physics School, Beijing 100081, China;,   Key Laboratory of Soft Matter Physics and Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
Published: December 2020

Dynamical behaviors of granular piles are systemically investigated by an experimental equipment and imaging and direct particle tracking during quasi-static avalanches and slow flow process. It is found that part of beads slides obliquely downward, meanwhile the other part of beads is almost fixed; layer-structure can be clearly observed, and it include flow-layers and static-layer. The flow-layers lie almost parallel to each other and the angles between the flow-layers and horizonal plane are approximately in the range 4050. Moreover, the slippage of the flow-layers from the static-layer begins to gradually increase linearly. In addition, the positions of initial flow-layer that has different volumes of granular piles tend to be fixed.
Variation of effective elastic moduli of a solid with transverse isotropy due to aligned inhomogeneities
Authors: Song Yong-Jia  , Hu Heng-Shan  ,   Department of Astronautics and Mechanics, Harbin Institute of Technology, Harbin 150001, China
Published: December 2020

In this paper the effective or overall moduli of a solid containing aligned ellipsoidal inhomogeneties, are derived by making the scattered displacement field equal to that scattered by a spherical–shaped effective medium in the same matrix. It is shown that the obtained formulae of effective elastic moduli are of second-order accuracy at least. The effective moduli decrease monotonically with porosity, thus excluding the unphysical behavior in Hudson’s model in which there is an increase of moduli with porosity when the porosity goes beyond a certain threshold. By integration of inhomegeneity orientation angle, the effective moduli can be obtained for a solid with randomly orientated inhomogeneities, which are the same as those in the Kuster-Toksöz model. Numerical calculations show that a rock with fluid-saturated inhomegeneities has a higher longitudinal wave modulus in the direction of TI symmetric axis than the modulus for a rock with empty inhomegeneities.
Splitting of transmission modes in a nanoscale metal ring resonator with a notch
Authors: Wang Tong-Biao  , Liu Nian-Hua  , Yu Tian-Bao  , Xu Xu-Ming  , Liao Qing-Hua  ,   Department of Physics, Nan Chang University, Nan Chang 330031, China;,   Institute for Advanced Study, Nan Chang University, Nan Chang 330031, China
Published: December 2020

A nanoscale metal ring resonator with a notch is proposed, in which the propagating characteristics of surface plasmons was studied with the help of finite-difference time-domain method. Influences of the length and position of the notch and the radius of the ring on the transmission properties of the ring resonator have been studied in detail. We found that, compared with the ring resonator without notch, the intrinsic mode of the ring resonator will split when the length and position of the notch satisfy some special conditions. In addition, the split modes will shift toward longer wavelengths as the radius of the ring increases, while the variation of the radius has no influence on the splitting behavior of the intrinsic modes.
Properties of reflecting region of periodic-structured thin film with refractive index dispersion
Authors: Liu Hua-Song  , Liu Dan-Dan  , Jiang Cheng-Hui  , Wang Li-Shuan  , Jiang Yu-Gang  , Sun Peng  , Ji Yi-Qin  ,   Tianjin Key Laboratory of Optical Thin Film, Tianjin Jinhang Institute of Technical Physics, Tianjin 300192, China
Published: December 2020

Periodic structure is the basic physical model in optical film design. Universal conditions of the reflecting center wavelength are given. With the refractive index dispersion of the layers, the reflecting center wavelength and the band characteristic of equal-thickness and unequal-thickness periodic structures are studied. According to experimental results, in both the equal-thickness and unequal-thickness periodic structures with the refractive index dispersion of the coating layers, the reflecting center wavelength moves towards the longer wavelengths, and the reflective series as well as the relative wave number will depart from linear relation. For the same optical thickness of the film with unequal-thickness periodic structure, when the optical thickness of the high refractive index layer is bigger than that of the low refractive index layer, the departure from linear relation between the reflective series and the relative wave number is higher. For the low reflective series, the bandwidth of unequal-thickness periodic structure is smaller than that of equal-thickness periodic structure. The influence of the layer dispersion on the bandwidth is found to be weak.
Nuclear magnetic resonance test and analysis on water phase of the ultra-soft soil under different load level and rate
Authors: Li Zhang-Ming  , Zeng Wen-Xiu  , Gao Mei-Lian  ,   Inst. of Geotechnical Engineering, Guangdong University of Technology, Guangzhou 510006, China;,   Shanghai Niumag Corporation, Shanghai 200333, China
Published: December 2020

In large-scale constructions, more and more ultra-soft soil foundation treatments are faced. The treatment purpose is to discharge as much as possible the pore water in the soft soil and make it consolidated, so as to improve its physical and mechanical performances. The static and dynamic drainage consolidation method is tried to use high-energy impact and convert part of the combined water in the ultra-soft soil into free water, and thus achieve more water discharge and effective consolidation. However, it is unclear what level and rate of the impact load could cause the water phase to change. For this, based on the tests with different load level and rate for the ultra-soft soil under simulated engineering condition, water phase test of the soil by nuclear magnetic resonance (NMR) was carried out, in order to explore the rules or conditions under which the combined water in this ultra-soft soil could be converted into free water at typical load level and rate. Our main conclusion is that: (1) corresponding to the engineering usual load, true tri-axial test at low load rate and level (1.6 MPa/s, the 100 kPa), the combined water in the ultra-soft soil cannot be converted into free water; (2) corresponding to the condition of high-speed impact load (a3787 kPa load level per blow and a rate of 631.2 MPa/s) used in the static and dynamic drainage consolidation method, the combined water in the ultra-soft soil could be converted into free water; and the greater the total impact energy, the easier the conversion into free water; (3) the effect of constraint sample confining stiffness on the conversion of combined water to free water can be ignored.
A target field method for designing cylindrical z-gradient coil combined with vibration control
Authors: Hu Ge-Li  , Ni Zhi-Peng  , Wang Qiu-Liang  ,   Institure of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190, China;,   Graduate University of Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

During the scanning of magnetic resonance imaging (MRI) system, the main acoustic noise source comes from the gradient coils. The gradient coils are turned on and off repeatedly, thus producing noise within the coil. With increasing magnetic field strength, the noise also increases. The primary method to reduce the noise is to decrease the distribution of the Lorentz forces. Target field (TF) method is very important for designing gradient coils which have been used in MRI and other applications. Many works based on the Turner’s traditional TF method have been proposed. In this paper, a target field method combined with vibration control has been presented to analyze the deflection of a cylindrical z-gradient coil because of the Lorentz forces. Simulation results via Matlab show that the maximum vibration amplitude can be reduced effectively by the new design method proposed in this paper.
Study on regulatory network of proteins based on DNA damage
Authors: Geng Du-Yan  , Xie Hong-Juan  , Wan Xiao-Wei  , Xu Gui-Zhi  ,   Province-Ministry Joint Key Laboratory of Electromagnetic Field and Electrical Apparatus Reliability Hebei University of Technology, Tianjin 300130, China
Published: December 2020

Each stage of cell growth is inseparable from the protein-protein interactions. It is of great significance in studying the function of the cell cycle, regulatory mechanism, and relationships among the proteins involved in the regulation in biological engineering and other fields. This paper studies the function, principle, and self-repairing mechanisms based on the intracellular protein p53 when DNA is damaged by ionizing radiation. We introduce more regulating factors for the proteins to build the networks based on the existing one and simulate a more comprehensive cell cycle progression. Then we analyze the anti-interference and self-repairing system of the regulatory networks using the complex network theory and cell cycle regulation. Numerical simulation results and experimental data show: (1) The protein network shows a stable condition when it suffers a small disturbance, while it shows a poor stability when facing deliberate attack; (2) whether the damaged DNA can be repaired depends on the dynamic behavior of p53 protein, i.e., p53 can transmit the damage signal to the cell cycle regulatory factors through the signal transduction pathway to induce the cell cycle arrest so as to complete the self-repairing processes in the case of the low-damage and the medium-damage. When DNA comes to face the high-damage and the excess-damage, the concentration of p53 shows a periodic oscillation behavior and it can induce apoptosis.
Simulation on reflection plate angles of the efficient black silicon PV modules
Authors: Wang Jian-Qiang  , Liu Bang-Wu  , Xia Yang  , Xu Zheng  ,   Institute of Microelectronics of Chinese Academy of Science, Key Laboratory of Microelectronics Devices & Integrated Technology, Institute of Microelectronics, Chinese Academy of Sciences, Beijing 100029, China;,   Key Laboratory of Luminescence and Optical Information, Beijing Jiaotong University, Ministry of Education, Institute of Optoelectronics Technology, Beijing Jiaotong University, Beijing 100044, China
Published: December 2020

In order to achieve maximum power output, common PV modules will deliberately make a certain angle, but still some light will be reflected from the surface of the common PV modules into the air and waste. This paper presents a reflective plate structure having efficient black silicon solar modules, and multi-angle light-absorbing black silicon components to construct a reflective plate structure that can take advantage of the reflected light. The angle between the reflectors and black silicon component was simulated in this paper, which shows that when the assembly angle of PV module is 34°, the optimum angle of the reflective plate is 16.5°, in this case, the battery’s power generation is increased by about 39% under the same illumination conditions.
Occurrence regularity of CPT discharge event in negative cloud-to-ground lightning
Authors: Zhou Wei  , Zhang Yang  , Zhang Yi-Jun  , Lü Wei-Tao  , Zheng Dong  , Chen Shao-Dong  , Pan Han-Bo  ,   Chengdu University of Information Technology, Chengdu 610225, China;,   State Key Laboratory of Severe Weather, Chinese Academy of Meteorological Sciences, Beijing 100081, China;,   Laboratory of Lightning Physics and Protection Engineering, Chinese Academy of Meteorological Sciences, Beijing 100081, China;,   Guangzhou Field Experiment Site for Lightning Research and Testing, Conghua 510925, China;,   Conghua Meteorological Bureau, Conghua 510925, China
Published: December 2020

Occurrence regularity of chaotic pulse trains (CPT) discharge event in negative cloud-to-ground (CG) lightning during six thunderstorms are analyzed in this paper. Results show that CPT is a common phenomenon throughout the negative CG lightning discharge process, 243 times of CPT discharge events occurs during 323 negative CG lightning, a proportion reaching 75.2%. CPT in negative CG can occur before the first return stroke, between the strokes, and after the last stroke. The proportion of 66.7% of the total subsequent strokes is preceded by CPT, and CPT occurs after 11.5% of the total last strokes. It is also found that there are four distributions prior to subsequent strokes: single CPT-c (CPT connecting with subsequent strokes), single CPT-i (CPT occurring in an interval between CPT and return strokes), CPT-c and CPT-i occur concurrently, and several CPT-is appear concurrently. Single CPT-c is the most common, 39.4% of subsequent strokes are preceded by single CPT-c, and several CPTs are easier to occur before the first and second subsequent strokes, which are respectively the corresponding strokes 9.4% and 7.7% of the total number. With the increase of the order of subsequent stroke, there is a decreasing trend for the occurrence of CPT, and in addition to the previous two subsequent strokes, the number of CPT-c is obviously greater than CPT-i before the others. In addition, CPT-i and CPT-a both occur to add on the negative CG K-change, and some also correspond to the process of J-change in the slow electric field wave.
Bivariate normal distribution of coherent state in parameterized phase space
Authors: Fan Hong-Yi  ,   Department of Physics, Ningbo University, Ningbo 315211, China;,   Department of Materials Science and Engineering, University of Science and Technology of China, Hefei 230026, China
Published: December 2020

Combining quantum mechanics and the normal distribution in statistics we study the coherent state from the point of view of statistics and by using the integration method within ordered product of operators. We find that the pure coherent state |z >z| exhibits a bivariate normal distribution of randon variables in (q,p) phase space, z=(q+ip)/√2, with a real k-parameter which is related to the quantization scheme, and the correlation coefficient is ik. For k=±1, |z >z| respectively is arranged as P-ordering (all P stand on the left of all Q) and Q-ordering (all Q stand on the left of all P), while in the case of k=0, |z >z| is arranged as the Weyl-ordering. In the cases of P-ordering and Q-ordering, in the classical correspondence function of |z >z||z=(q+ip)/√2 the bivariates (q,p) are correlated, only in the case of Weyl correspondece, (q,p) are independent. In other words, the Weyl ordering of operators is liable to decouple the correlation in bivariates.
Asymptotic stability for non-cooperative program game model of the capacity analysis for mobile ad-hoc networks with variable time delay
Authors: Yang Juan  , Yang Dan  , Huang Bin  , Zhang Xiao-Hong  , Yang Cong  ,   College of Communication Engineering, Chongqing University, Chongqing 400030, China;,   The 3rd Department, PLA.Chongqing Communication Institute, Chongqing 400035, China;,   School of Software Engineering, Chongqing University, Chongqing 400030, China;,   Foundation department, PLA.Chongqing Communication College, Chongqing 400035, China;,   The1rd Department, PLA.Chongqing Communication Institute, Chongqing 400035, China
Published: December 2020

Stability of capacity is one of the key properties for quality of service (QoS) support in mobile ad hoc networks (MANETs). In this paper, a novel technique is proposed for controlling the stability of capacity analysis model for non-cooperative program game MANETs, with the time-varying propagation delay taken into consideration. First, based on the obtained source node flow transmitting rate evolution aligns of capacity analysis model for non-cooperative program game mobile ad-hoc network, when adding the time-varying propagation delay term, which is a class of nonlinear time-varying delay differential aligns, the asymptotic stability criteria of the model are presented in the form of descriptor and linear matrix inequalities. Then, an iterative algorithm is also provided for controlling the stability of the model. The proposed criteria are less conservative since they are based on an equivalent model transformation. Simulation experiments verify the effectiveness of this algorithm. Although the model used in this paper focuses on a specific algorithm, we believe that this method has a great potential in analyzing and understanding the general capacity of MANETs stability control issues.
Influence of heat leakage on entransy dissipation minimization of heat exchanger
Authors: Xia Shao-Jun  , Chen Lin-Gen  , Ge Yan-Lin  , Sun Feng-Rui  ,   Institute of Thermal Science and Power Engineering, Naval University of Engineering, Wuhan 430033, China;,   Military Key Laboratory for Navy Ship Power Engineering, Naval University of Engineering, Wuhan 430033, China;,   College of Power Engineering, Naval University of Engineering, Wuhan 430033, China
Published: December 2020

Model of a heat transfer process in heat exchanger with heat leakage is established in this paper. Both the heat flux between the hot and cold fluids and the heat leakage between the cold fluid and outside environment are assumed to obey Newtonian heat transfer law. On condition that the net amount of heat transferred by the cold fluid is given, the optimal temperature configurations of the hot and cold fluids for the minimum entransy dissipation of the heat transfer process are derived by using the optimal control theory. Optimal paths are also compared with the conventional strategies of heat transfer under constant hot fluid temperature and constant heat flux rate operation. The results obtained in this paper could provide some theoretical guidelines for the optimal design and operation of real heat exchangers.
A density functional theory study of small bimetallic PtnAl (n=18) clusters
Authors: Wen Jun-Qing  , Xia Tao  , Wang Jun-Fei  ,   College of Science, Xi’an Shiyou University, Xi’an 710065, China;,   Institute of Modern Physics, Northwest University, Xi’an 710069, China
Published: December 2020

The geometries, stabilities and electronic properties of PtnAl (n=18) clusters are calculated using density functional theory at BPW91/LANL2DZ level. The stabilities of the ground states of PtnAl (n=18) clusters are discussed by means of the binding energy, the second difference in energy and energy gaps, and the magnetic properties. Mulliken charges are studied. The growth patterns for different sized PtnAl (n=18) clusters are of Al-substituted Ptn+1 clusters and they keep a similar framework of the most stable Ptn+1 clusters except Pt2Al. Al atoms in the ground state PtnAl isomer tend to occupy the most highly coordinated positions. The analyses of stabilities show that PtAl and Pt4Al are more stable than other clusters. Mulliken population analysis shows that charges are transferred from Al atoms to Pt atoms, which indicates that Al atom acts as electron donor in all PtnAl clusters. The analysis of magnetic property shows that doping an Al atom reduces the average atomic magnetic moment of the host Pd cluster. Pt-rich clusters which have a strong nonlinear optical effect and are easy to polarize by external electromagnetic field.
Theoretical study of the influence of femtosecond pump-probe pluse on the photoionization of NaLi molecule
Authors: Zhang Min  , Tang Tian-Tian  , Zhang Chao-Min  ,   Department of Basic Education, Yantai Nanshan University, Yantai 265713, China
Published: December 2020

In this work, using three-state model and time-dependent wave packet method, the wave packet dynamic process and time-resolved photoelectron spectrum of NaLi molecule in femtosecond pump-probe intense laser field are investigated and the relation between the parameter of the femtosecond laser and time-resolved photoelectron spectrum is obtained. It is found that the vibrational periods of wave packet are different for different laser wavelengths and the photoelectron spectra are different for different pump-probe delay times. The height and position of the peak of the photoelectron spectrum change with pump-probe delay time. When 1=352 nm and t=400 fs, the corresponding signal in the outer well (0.5 eV) is obviously smaller than that in the inner well (1.35 eV). The result reveals that the time-resolved photoelectron spectrum reflects the information about the wave packet dynamic of the excited state 41+ The results may be useful for realizing the optical control of molecule and the process of quantum manipulation of molecule experimentally, and provide some important basis for further theoretical research in this respect.
Influence of collision energy and reagent vibrational excitation on the stereodynamics of reaction Ar+H2+→ArH++H
Authors: Hu Mei  , Liu Xin-Guo  , Tan Rui-Shan  ,   College of Physics and Electronics, Shandong Normal University, Jinan 250014, China
Published: December 2020

The quasi-classical trajectory is calculated for the reaction Ar+H2+→ArH++H (12A’) on the latest potential surface. The correlated integral reaction cross section, P(θr), P(φr) distribution and the polarization dependent differential cross sections polariztion dependent differential cross sections (PDDCSs) are discussed in detail. The results show that the integral reaction cross sections are well consistent with the experimental values at different collision energies and reagent vibrational excitations which indicates that our potential energy surface is accurate. The results indicate that the vibration excitation has less influence on the P(θr) distribution than the collision energy. The P(φr) distribution, and PDDCS are quite sensitive to collision energy and reagent vibrational excitation.
Experimental study on hypervelocity impact characteristics of density-grade thin-plate
Authors: Hou Ming-Qiang  , Gong Zi-Zheng  , Xu Kun-Bo  , Zheng Jian-Dong  , Cao Yan  , Niu Jin-Chao  ,   Science and Technology on Reliability and Environment Engineering Laboratory, Beijing Institute of Spacecraft Environment Engineering, China Academy of Space Technology, Beijing 100094, China;,   Institute of Telecommunication Satellite, China Academy of Space Technology, Beijing 100094, China
Published: December 2020

Hypervelocity impact (HVI) characteristics of Ti6Al4V/Ly12 Al/polyamide fibre density-grade thin-plate are investigated experimentally in a velocity range of 4.0–6.5 km/s by using two-stage light gas gun. The perforation in target, damage to witness wall, and ballistic limit curve are obtained and compared with those in the case of aluminum thin-plate. The results show that the diameter of the perforation hole is larger than that of aluminum thin-plate, the crater size in witness plate is smaller, and the ballistic limit curve is 50% larger than the latter. The analysis of shock wave propagation and the calculation of energy dissipation property in the density-grade thin-plate show that higher peak shock pressure is produced in it, and it has longer pressure duration time. Thus, more dissipation energy is consumed than in the case of aluminum thin-plate. So the density-grade thin-plate has a very good performance in withstanding HVI, and is promising in engineering application, e.g. protecting spacecraft from HVI of micro-meteoroid and orbital debris.
Phase field modeling of the evolution of partical interface shape distribution during coarsening
Authors: Luo Hai-Bin  , Li Jun-Jie  , Ma Yuan  , Guo Chun-Wen  , Wang Jin-Cheng  ,   State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072, China
Published: December 2020

Three-dimensional simulations of particles coarsening in a solid-liquid two-phase system are investigated using the multiphase-field model. The evolution of the interface shape distribution during coarsening is analyzed. And the influences of the volume fraction on the interface shape distribution and coarsening rate are studied under different coalescence conditions. The simulation results show that the influence of volume fraction on the change of coarsening rate is delayed when there exists coalescence between solid particles under high volume fraction. Moreover, with the evolution of coarsening, proportion of the hyperboloid with high curvature decreases and the proportion of ellipsoid with low curvature increases. No matter whether the coalescence between particles occurs, the interface shape distribution has self-similarity after a period of time of evolution. But it will take a longer time for the system to reach the steady state with the increasing of volume fraction.
Progress of flexible organic non-volatile memory field-effect transistors
Authors: Chai Yu-Hua  , Guo Yu-Xiu  , Bian Wei  , Li Wen  , Yang Tao  , Yi Ming-Dong  , Fan Qu-Li  , Xie Ling-Hai  , Huang Wei  ,   School of Electrical and Information, Northeast Agricultural University, Haerbin 150030, China;,   Institute of Advanced Materials, Nanjing University of Posts and Telecommunacations, Nanjing 210023, China;,   Institute of Advanced Materials, Nanjing University of Technology, Nanjing 211816, China
Published: December 2020

Flexible organic non-volatile memory field-effect transistors (ONVMFETs) are promising candidates in the field of flexible organic electronic devices, which can be used in flexible radio frequency tags, memories, integrated circuits and large-area displays, because of their remarkable advantages such as flexibility, lightweight, low cost and large-area organic electronics. On the basis of the introduction of the development of flexible ONVMFETs in terms of substrates, structures and characteristics, the classification of flexible ONVMFETs is summarized. Meanwhile, we discuss the effects of mechanical stress and temperature on the performance of flexible ONVMFET. Finally, some prospects as well as the challenges are pointed out.
Molecular beam epitaxy of single unit-cell FeSe superconducting films on SrTiO3(001)
Authors: Wang Meng  , Ou Yun-Bo  , Li Fang-Sen  , Zhang Wen-Hao  , Tang Chen-Jia  , Wang Li-Li  , Xue Qi-Kun  , Ma Xu-Cun  ,   School of Electronic Engineering, Beijing University of Posts and Telecommunications, Beijing 100876, China;,   State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China;,   State Key Laboratory for Surface Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
Published: December 2020

Based on our previous work, we have systematically investigated the molecular beam epitaxy growth of single unit-cell FeSe films on SrTiO3(001) substrates and studied the surface morphology by scanning tunneling microscopy. We found that there are three key steps to obtain large-scale uniform one unit-cell superconducting FeSe films. First, the STO(001) substrates should be treated by HCl etching and thermal annealing under oxygen flux so that a specific TiO2-terminated STO(001) surface with well-defined step-terrace structure could be obtained. Second, the Fe and Se fluxes and substrate temperature have to be controlled delicately. At last, post-growth annealing is also critical, which can remove extra Se adatoms, and more importantly facilitate the necessary electron transfer for superconductivity transition.
Properties of the internal excited state of the strong-coupling magneto-bipolaron in a parabolic quantum dot
Authors: Eerdunchaolu  , Bai Xu-Fang  , Han Chao  ,   Department of Physics, Hebei Normal University of Science and Technology, Qinhuangdao 066004, China;,   College of Physics and Electronic Information, Inner Mongolia University for Nationalities, Tongliao 028043, China
Published: December 2020

The properties of the internal excited state of the strong coupling magneto-bipolarons in a parabolic quantum dot are studied by using the variational method of Pekar type based on the Lee-Low-Pines’ unitary transformation. With the influences of the electronic spin and the external magnetic field taken into consideration, the change law of ground state energy E0, the average number of phonon N0, the first excited state energy E1 and the average number of phonon N1 of the magneto-bipolarons with the confinement strength ω0, the dielectric constant ratio η, the electron-phonon coupling α, and the cyclotron frequency ωc are derived in two-dimensional quantum dot. Numerical results indicate that the ground state energy E0 and the first excited state energy E1 consist of four parts: the single-article energy Ee of two electrons, the Coulomb interaction energy EC between two electrons, the interaction energy Es between the electronic spin and the external magnetic field, and the interaction energy Ee-ph of the electron with the longitudinalo optical phonons. The energy E1 of the first excited state splits into two lines, i.e., E1(1+1) and E1(1-1) due to the interaction between the “orbital” motion of the single-particle and the magnetic field, and each level of the ground-state energy and the first excited state energies set produces three “fine structures” due to the interaction between the electronic spin and the magnetic field. N0 and N1 increase with ω0, α and ωc increasing; Ee-ph is always less than zero, and absolute value |Ee-ph| increases with ω0, α and ωc increasing. The electron-phonon interaction has an important influence on the formation of bound state of the magneto-bipolaron; but the confinement potential and coulomb repulsive energy between electrons are unfavorable for the formation of magneto-bipolaron in the bound state.
Photoluminescence from plasmon-enhanced single InAs quantum dots
Authors: Wang Hai-Yan  , Dou Xiu-Ming  , Ni Hai-Qiao  , Niu Zhi-Chuan  , Sun Bao-Quan  ,   State Key Laboratory for Superlattices and Microstructure, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
Published: December 2020

Photoluminescences (PLs), time-resolved PL spectra, and PL intensities each as a function of excitation power from plasmon-enhanced single InAs quantum dots (QDs) are measured for studying the effect of photoluminescence enhancement at a low temperature of 5 K. The 5 nm gold films are deposited on the surface of InAs QD sample by using electron beam evaporation technique, which form nano-gold island membrane structures. It is found that the gold island film is conducive to the enhancement of QD PL intensity and the maximal PL intensity increases up to about 5 times the PL intensity without gold island film. The physical mechanism of the PL increase is that the gold island film nanostructure can improve the QD PL collection efficiency which is very important for realizing the bright single photon sources.
Particle-in-cell simulation on effect of outgassing on flashover and breakdown on dielectric surface in high-power microwave environment
Authors: Dong Ye  , Dong Zhi-Wei  , Zhou Qian-Hong  , Yang Wen-Yuan  , Zhou Hai-Jing  ,   Institute of Applied Physics and Computational Mathematics, Beijing 100094, China
Published: December 2020

For investigating the mechanism of high power microwave flashover and breakdown on dielectric surface with outgassing, firstly, the theoretical modeling is put forward, including dynamic equations, particle-in-cell (PIC) method, secondary emission, Monte-Carlo collision (MCC) method and outgassing model. Secondly, based on the theoretical modeling, the 1D3V PIC-MCC code is programmed by authors. By using this code, the flashover and breakdown on dielectric surface with weak and strong outgassing course under different gas moving velocities are studied numerically. The numerical results are concluded in the following. The flashover and breakdown on dielectric surface are caused by continuous increase of deposited power. For weak outgassing, multipacting is dominant. As outgassing coefficient increases, multipacting is promoted by ionization collision. The typical phenomena are the increases of space-charge field, average energy of surface-collision electrons and the number of surface-collision electrons. Here, the surface-collision electrons are caused by multipacting mostly. With the increase of gas molecule velocity, ionization course is suppressed by gas pressure decreasing near to the dielectric surface. For strong outgassing, ionization collision is dominant. As outgassing coefficient increases, the number of ions increases exponentially with ionization frequency increasing, multipacting is suppressed by ionization collision. The typical phenomena are the negative value of space-charge field on dielectric surface, the decrease of average energy of surface-collision electrons, and the exponential increase of surface-collision electrons caused by ionization collision near to dielectric surface. Here, the surface-collision electrons are caused by ionization mostly. With the increase of gas molecule velocity, the depth of gas is enlarged, thereby promoting the ionization collision.
A statistical model to predict the steady-state creep rate
Authors: Li Jing-Tian  , Wang Jian-Lu  , Zhang Bang-Qiang  , Rong Xi-Ming  , Ning Xi-Jing  ,   Institute of Modern Physics, Fudan University, Shanghai 200433, China;,   Dongfang Turbine Co. Ltd., Deyang 618000, China;,   Department of Optical Science and Engineer, Fudan University, Shanghai 200433, China
Published: December 2020

For a long time, empirical formulars have been used to predict the steady-state creep rate due to lack of clear microscopic description of the mechanism, which frequently leads to unreliable predictions. In this work, a statistical model of single atom developed recently is used to predict the steady-state creep rate at an atomic diffusion level. To test the model, we measure the creep rates of three kinds of materials, i.e., 42CrMoA, 2Cr12Ni, and 1Cr12Mo, and collect the experimental data of other materials, such as IN738LC and K435. The results show that our theoretical predicts are in good agreement with the experimental results.
High temperature oxidation resistance of cluster model designed alloys Cu-Cu12-[Mx/(12+x)Ni12/(12+x)]5 (M=Si, Cr, Cr+Fe)
Authors: Li Xiao-Na  , Zheng Yue-Hong  , Li Zhen  , Wang Miao  , Zhang Kun  , Dong Chuang  ,   Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, Ministry of Education, School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024, China;,   Changzhou Institute of Dalian University of Technology Corporation, Changzhou 213164, China;,   School of Mechanical Engineering, Dalian University of Technology, Dalian 116024, China
Published: December 2020

Based on the stable solid solution cluster model, cupronickel is microalloylized in this paper. Alloys with different Ni-M (M=Si, Cr, Cr+Fe) ratios are designed at constant atomic ration of Cu (72.22 at.%). The high temperature oxidation resistance and mechanism of alloy are also investigated. In the Cu-Ni-Si system, the addition of Ni-Si can enhance the oxidation resistance of the alloy from two aspects: firstly, the Ni-Si is in solid solution state when being added as a cluster, it can inhibit the chemical reactivity of Cu-Ni-Si alloy; secondly, anti-oxidation precipitation can be obtained with the increase of Si/Ni ratio. Therefore, the oxidation resistance of the alloy is not because of the formation of the compact silicon oxide film. In the Cu-Ni-Cr system, the oxidation is obviously inhibited at medium temperatures (lower than 800 ℃). But at higher temperatures, the oxidation resistance is relevant to the integrality of chrome oxide layer. The high temperature oxidation resistance is closely related to Cr/Ni ratio, hence an appropriate Cr/Ni ratio is necessary for the good high temperature oxidation resistance. Compared with the third element Cr, the forth element Fe cannot be oxidized first. Therefore, combined addition of Cr and Fe can only inhibit the medium temperature oxidation, but not high temperature oxidation.
A broadband transmission absorption polarization-independent metamaterial absorber
Authors: Lu Lei  , Qu Shao-Bo  , Shi Hong-Yu  , Zhang An-Xue  , Xia Song  , Xu Zhuo  , Zhang Jie-Qiu  ,   Science College, Air Force Engineering University, Xi’an 710051, China;,   School of Electronics and Information Engineering, Xi’an Jiaotong University, Xi’an 710049, China;,   Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education, Xi’an Jiaotong University, Xi’an 710049, China
Published: December 2020

In this paper, we propose a new metamaterial absorber based on magnetic absorbing material. This absorber has the characteristics of low-frequency transmission and high-frequency broadband absorption. The transmission coefficient of the metamaterial absorber is-0.5 dB at 1 GHz: the good low-frequency transmission property can realize intercommunication between the low-frequency signals. The absorptivity is greater than 80% in the frequency range above 8.4 GHz, which almost covers all the X-band and Ku-band frequencies. In addition, the metamaterial absorber is polarization-independent due to the fourfold rotational symmetry of the unit cell metallic periodic structure. The metamateiral absorber has the advantages of simple design, strong practicability, and high potential application value.
Effect of deposition temperature on growth, structure and mechanical properties of diamond-like carbon films co-doped by titanium and silicon
Authors: Jiang Jin-Long  , Huang Hao  , Wang Qiong  , Wang Shan-Min  , Wei Zhi-Qiang  , Yang Hua  , Hao Jun-Ying  ,   Department of Applied Physics, Lanzhou University of Technology, Lanzhou 730050, China;,   State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China
Published: December 2020

Titanium and silicon co-doped diamond-like carbon films are deposited on Si substrates by middle-frequency magnetron sputtering Ti80Si20 composite target. The influences of deposition temperature on the growth rate, chemical composition, structure, surface and mechanical properties of the film are investigated. The results show that the growth rate of the film decreases as substrate temperature increases. With the increasing of substrate temperature, Ti and Si atom content values in the film increase, while C atom content value decreases. At high temperatures, the film has low sp3C fraction, surface contact angle, compressive stress, and high hardness, and elastic modulus. The influences of deposition temperature on the growth and bonding structure of the film are analyzed in view of the subplantation growth model. The changes in surface and mechanical properties are correlated with the growth mechanism and microstructures of the film.
Self-similarity and frequency-mixing phenomena analysis of multi-frequency controlled switching converter
Authors: Wu Song-Rong  , Zhou Guo-Hua  , Wang Jin-Ping  , Xu Jian-Ping  , He Sheng-Zhong  ,   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

Based on the operation principle and state equations of multi-frequency (MF) controlled switching converter, the discrete iterative map model is established, the corresponding characteristics equation and Lyapunov exponent of MF controlled switching converter operating in discontinuous conduction mode are derived. According to the discrete iterative map model, its bifurcation behaviors are investigated. It is found that the border-collision bifurcation and the multi-period behaviors occur in converter, when the circuit parameters are varied. When the voltage error boundary is too large, the converter behaves as self-similarity phenomenon, and when the voltage error boundary is too small, the converter behaves as frequency-mixing phenomenon. The converter stability is investigated by Lyapunov exponent, which validates the correctness of bifurcation analysis. Time-domain waveforms and phase portraits of converter with the load varied, are analyzed by circuit simulation, which validates the validity of discrete iterative map model and the correctness of theoretical analysis. Finally, simulation results in this paper are verified by experimental results.