bluuebunny/crossref_metadata_2025 huggingface dataset:
Analytical model of single event crosstalk in near space
Authors: Liu Bao-Jun  , Cai Li  ,   Science Institute, Air Force Engineering University, Xi' An 710051, China
Published: December 2020

With feature size scaling down, the influence of crosstalk on single event effect becomes more important. In order to analytically describe the influence of crosstalk effect on single event transient (SET), based on the equivalent circuits of SET and 6-node template model for interconnects, by using defined four rules of point admittance to simplify the calculation, the analytical model for single event crosstalk (SEC) is deduced. Through differentiating and Taylor series expansion theorem, the expression for the peak value of crosstalk voltage is achieved. The simulation results show that the analytical model is well consistent with SPICE circuits and average relative error is 2.51%, and max error is 5.11%.
Effect of 4 GPa pressure treatment on the solid state transformation kinetics of T8 steel in heating process
Authors: Chen Yan  , Li Ya-Li  , Liu Jian-Hua  , Zhang Rui-Jun  ,   State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004, China;,   College of Environmental and Chemical Engineering, Yanshan University, Qinhuangdao 066004, China;,   Tangshan Vocational Technology College, Tangshan 063000, China
Published: December 2020

The transformation temperatures and durations of solid state transformation in T8 steel before and after 4 GPa pressure treatment are measured using differential scanning calorimetry, and the transformation activation energy and Avrami exponent are also calculate. Then the effects of 4 GPa pressure treatment on solid state transformation kinetics in T8 Steel are investigated based on the kinetic parameters and the observation of microstructure. The results show that the solid state transformation in T8 steel shifts toward the low temperature region after 4 GPa pressure treatment. The high pressure treatment can reduce the phase transformation time and Avrami exponent and enhance the phase transformation activation energy, which is favorable for refining the grains but has little effect on the phase transformation mechanism.
First-principles calculations of optical and mechanical properties of LiBX2 (B= Ga, In; X= S, Se, Te)
Authors: Ma Tian-Hui  , Zhuang Zhi-Ping  , Ren Yu-Lan  ,   College of Chemistry and Chemical Engineering, Mudanjiang Normal University, Mudanjiang 157012, China
Published: December 2020

First-principles calculations of optical and mechanical properties of LiBX2 (B= Ga,In; X= S,Se,Te) are performed using plane-wave pseudopotential method. According to the order of band gaps, the order of laser induced damage thresholds is LiGaS2 > LiInS2 > LiGaSe2 > LiInSe2 > LiGaTe2 > LiInTe2. The elastic constants of these crystals can all meet the mechanical stability conditions at normal pressure, and the plasticitics and ductilities of indium compounds are better than those of gallium compounds. Theoretical values of average static electronic dielectric constant ε1(0), average ordinary refraction index n0 and birefringence index Δn of these crystals are in good agreement with the experimental data. LiGaS2, LiInS2, LiGaSe2, LiInSe2 and LiGaTe2 compounds have the large birefringences and their absorption and reflectivity spectra are transmissible through mid- and far-IR region, so the five crystals are likely to be promising materials for nonlinear optical applications in the mid- and far-IR region.
Ultrafast carrier dynamics in CdTe/CdS Core/Shell quantum dots
Authors: Li Xia  , Feng Dong-Hai  , He Hong-Yan  , Jia Tian-Qing  , Shan Lu-Fan  , Sun Zhen-Rong  , Xu Zhi-Zhan  ,   State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China;,   State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, China
Published: December 2020

On the basic of the synthesis of CdTe/CdS core/shell quantum dots (QDs) in aqueous phase, we study ultrafast carrier dynamic behaviors of CdTe/CdS QDs with different shell thicknesses, by using femtosecond time-resolved transmission spectroscopy. The results show that both the buildup time of the lowest exciton state and its following relaxation time become longer as CdS shell thickness increases. The results also indicate that the buildup rate of a space-separate exciton is slower than that of a space-overlapped exciton, and that carrier relaxation changes from surface-defect related mechanism into surface-passivated charge separation regime, which is consistent with steady-state absorption and photoluminescence experiments.
Investigation of thermodynamic progress of silicon ablated by nanosecond uv repetitive pulse laser
Authors: Bao Ling-Dong  , Han Jing-Hua  , Duan Tao  , Sun Nian-Chun  , Gao Xiang  , Feng Guo-Ying  , Yang Li-Ming  , Niu Rui-Hua  , Liu Quan-Xi  ,   College of Electronics & Information Engineering, Sichuan University, Chengdu 610064, China;,   Laboratory for Extreme Conditions Matter Properties, Southwest University of Science and Technology, Mianyang 621010, China;,   Chengdu Fine Optical Engineering Research Center, Chengdu 610041, China;,   Southwest Institute of Technical Physics, Chengdu 610041, China
Published: December 2020

The blind holes processing experiment is conducted on the silicon under the radiation of a 355 nm nanosecond UV repetitive pulse laser. With the increase of the laser pulse number, the variations of the silicon morphology,the depth and aperture of the blind holes are observed, and the thermodynamic process of UV laser irradiating silicon is analyzed. The results show that the formation of the blind silicon hole in the laser ablation process is due to the interaction between thermal effect and force effect. Thermal effect results in fusion, vaporization and even producing laser plasma by ionization in silicon, which is essential to the removal of the material. The molten material is compressed by the plasma shock wave and the expansion of the high-temperature gaseous material,and then ejection outward, which will benefit the further ablation; the force propagates along the laser transmission direction,perpendicular to the silicon surface, so the removal parts are distributed mainly along the depth direction of the hole, reaching a high aperture ratio, which is up to 8:1 in our experiments. In addition, the laser-induced plasma also prevents the effect of laser on the target surface, and with the increase of hole depth, laser defocusing occurs. The two aspects finally restrict the ablation depth. The results shows that in the process of laser irradiation on the material, the ablation efficiency is much higher when the former 100 pulses arrived than the sequent laser pulses.
Preparation and structure of CuInS2 film by the direct current triode sputtering
Authors: Yu Dan-Yang  , Kobayashi-Yasuyuki  , Kobayashi-Satoshi  ,   Department of Electronic Information Materials, Shanghai University, Shanghai 200072, China;,   Faculty of Engineering, Niigata University, Niigata 950-21, Japan
Published: December 2020

CuInS2 thin films are deposited on Pyrex slide glass substrates by direct current triode sputtering using CS2 as a reactive gas and Cu/In mixed metal plate as sputtering target. The effects of substrate temperature and area ratio of Cu to In on the crystalline structure and composition of CuInS2 films are discussed under the same growth condition (0.02 Pa of CS2 partial pressure). When sputtering time is 2 h, their thickness are obtained to be 1-2 μm. The CuInS2 films are characterized by EPMA, XRD, and so on. The results show that the optimal CuInS2 films are obtained at a ratio of 1.4 and growth temperatures of 150 ℃, 250 ℃ and 350 ℃, and that these films each have a chalcopyrite structure. The content of carbon impurity in each of the as-deposited CuInS2 films is found to be about 8.9%.
Predictability-based extended-range ensemble prediction method and numerical experiments
Authors: Zheng Zhi-Hai  , Feng Guo-Lin  , Huang Jian-Ping  , Chou Ji-Fan  ,   National Climate Center, China Meterological Administration, Beijing 100081, China;,   College of Atmospheric Sciences, Lanzhou University, Lanzhou 730000, China
Published: December 2020

Ensemble prediction is an effective approach to accounting for uncertainties of initial conditions and model error. By combining the predictability of extended-range, both predictable components and unpredictable random components with different characteristics are treated with different ensemble prediction schemes and strategies. A new predictability-based extended-range ensemble prediction method (PBEP) is proposed. In this method, for predictable component, the uncertainty of model is taken into account through the use of multiple error correction scheme; while the random component probability distribution is obtained from the climate probability distribution of historical data, for the sake of avoiding the influence of model error. Prediction results show that the ensemble prediction method can improve the forecast skill in all regions of the world, and the extents of improvement are different for waves with different spatial scales compared with the operational dynamical extended-range ensemble prediction system of NCC/CMA, exhibiting its potential application perspective to operational extended-range prediction.
The renormalization solution for a class of relative rotation nonlinear dynamic model with multi-frequency excitation
Authors: Tang Rong-Rong  ,   Faculty of Science, Huzhou Teachers College, Huzhou 313000, China
Published: December 2020

Using the perturbation theory, a class of relative rotation nonlinear dynamical model possessing nonlinear elastic force, friction force and multi-frequency excitation is investigated. The relations for the frequency syntheses are investigated, and the conditions under which multi-typical resonance happens at the same time are given. Using the renormalization method, the asymptotic expansions for the solutions of the model under corresponding conditions are obtained.
Infinite sequence new exact solutions of K(m,n) equation and B(m,n) equation
Authors: Bai Yu-Mei  , Taogetusang  , Han Yuan-Chun  ,   College of Mathematical, Inner Mongolia University for Nationalities, Tongliao 028043, China;,   College of Mathematical Science, Inner Mongolia Normal University, Huhhot 010022, China;,   College of Physics and Electronics, Inner Mongolia University for Nationalities, Tongliao 028043, China
Published: December 2020

New solutions of several kinds of auxiliary equations, Bcklund transformation and nonlinear superposition formula of the solutions are presented by studying a highly auxiliary equation method. Based on this and different m and n, the method of combining transformation and direct integration is used to obtain infinite sequence new exact solutions of K(m,n) equation and B(m,n) equation, which include infinite sequence smooth soliton solutions, peak soliton solutions and compact soliton solutions.
Study on the dynamics of an inelastic bouncing ball
Authors: Zhou Zhi-Gang  , Shi Yu-Ren  , Liu Cong-Bo  , Wang Guang-Hui  , Yang Hong-Juan  ,   Key Laboratory of Atomic and Molecular Physics and Functional Materials of Gansu Province, College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070, China;,   Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
Published: December 2020

Considering the case of air damping, we use the method of numerical simulation to study dynamic behavior of inelastic bouncing ball. By changing the value of control parameter V0, the motion of the bouncing ball exhibits nonlinear phenomena of period doubling bifurcation, chaos, etc. These phenomena are confirmed by both 0-1 test and maximal Lyapunov exponent.
Exact solution for mean trapping time of random walk on a scale-free Koch network
Authors: Xing Chang-Ming  , Liu Fang-Ai  , Xu Ru-Zhi  ,   Shandong Financial Information Engineering Research Center, School of Computer Science and Technology, Shandong University of Finance and Economics, Jinan 250014, China;,   School of Information Science and Engineering, Shandong Normal University, Jinan 250014, China
Published: December 2020

As a basic dynamical process, random walk on networks is fundamental to many branches of science, and has attracted much attention. A difficult problem in the study of random walk is how to obtain the exact solution for the mean trapping time (MTT) of this process. The MTT is defined as the mean time for the walker staring from any node in the network to first reach the trap node. In this paper, we study random walk on the Koch network with a trap located at the highest degree node and calculate the solution for MTT. The accurate expression for the MTT is obtained through the recurrence relation and the structure properties of the Koch network. We confirm the correctness of the MTT result by direct numerical calculations based on the Laplacian matrix of Koch network. It can be seen from the obtained results that in the large limit of network size, the MTT increases linearly with the size of network increasing. Comparison between the MTT result of the Koch network with that of the other networks, such as complete graph, regular lattices, Sierpinski fractals, and T-graph, shows that the Koch has a high transmission efficiency.
Oscillations and their mechanism of compound system with periodic switches between two subsystems
Authors: Yu Yue  , Zhang Chun  , Han Xiu-Jing  , Bi Qin-Sheng  ,   Faculty of Civil Engineering and Mechanics, Jiangsu University, Zhenjiang 212013, China;,   Faculty of Science, Nantong University, Nantong 226019, China
Published: December 2020

Complicated behaviors of the compound system with periodic switches between two nonlinear systems are investigated in detail. Through the local analysis, the critical conditions such as fold bifurcation and Hopf bifurcation are derived to explore the bifurcations of the compound systems with different stable solutions in the two subsystems. Different types of oscillations of the switched system are observed of which, the mechanism is presented to show that the trajectories of the oscillations can be divided into several parts by the switching points, governed by the two subsystems, respectively. With the variation of the parameters, cascading of doubling increase of the switching points can be obtained, leading to chaos via period-doubling bifurcations. Furthermore, because of the non-smooth characteristics at the switching points, different forms of bifurcations may occur in the compound system, which may result in complicated dynamics such as chaotic oscillations, instead of the simple connections between the trajectories of the two subsystems.
Design of extraordinary-optical-transimission refractive-index sensor of subwavelength metallic slit array based on a Fabry-Perot model
Authors: Zeng Zhi-Wen  , Liu Hai-Tao  , Zhang Si-Wen  ,   Key Laboratory of Optical Information Science and Technology, Ministry of Education, Institute of Modern Optics,Nankai University, Tianjin 300071, China
Published: December 2020

The refractive index sensing properties of a period array of subwavelength metallic slits in water environment are investigated. The transmission spectra of the slit array are calculated with a rigorous fully-vectorial method. A simple semi-analytical Fabry-Perot model that can accurately reproduce the rigorous fully-vectorial data is built up. We find that the transmission peak becomes sharpest as it is exactly located at the Rayleigh anomaly position, which is explained based on the resonance condition derived from the model. The method to design the slit array to achieve this sharpest transmission peak is presented. The full width at half-maximum (δλ) of the designed transmission peak can be as low as 0.01 nm, which corresponds to a refractive-index measurement uncertainty (δns) of 2× 10-6 RIU. The influences of array period, slit width and incident angle on the designed sensitivity, δλ, δns and peak transmittance of the sensor are systematically provided.
Transferring single-atoms between two red-detuned far-off-resonance optical dipole traps
Authors: Wang Cheng  , Xu Peng  , He Xiao-Dong  , Wang Jin  , Zhan Ming-Sheng  ,   State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China;,   Center for Cold Atom Physics, Chinese Academy of Sciences, Wuhan 430071, China;,   University of Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

The preparation and manipulation of single neutral atoms in optical dipole traps have important applications in quantum simulation and information. For this purpose, a single neutral atom, trapped in a static optical dipole trap which is formed by a strongly focused red-detuned far-off-resonance laser, can be transferred to a movable optical dipole trap when the movable trap crosses the static trap and the transfer efficiency can reach about 94%, meanwhile this transferred atom could be located at given position in the focal plane. This experimental result has potential applications in realizing entanglement of two individual neutral atoms in an optical dipole trap array.
Design and study of elliptical cylinder external cloak based on line-transformation
Authors: Wang Zhan  , Dong Jian-Feng  , Liu Jin-Jing  , Luo Xiao-Yang  ,   Institute of Optical Fiber Communication and Network Technology, Ningbo University, Ningbo 315211, China
Published: December 2020

Electromagnetic external cloak is an important device, which can make an object outside its domain invisible, meanwhile the object can exchange information with the outer region. Based on line-transformation and the concept of complementary medium, an elliptical cylindrical external cloak with only axial parameter changed is designed in this paper. The expressions of material parameters are derived, and then the performance of the elliptical cylindrical external cloak is simulated using the full wave simulation software. The results obtained confirm the correctness of constitutive parameters tensor. In addition, the effects of loss on performation of external cloak are investigated. Finally, the distribution of constitutive tensors is also investigated. This work provide a feasible way to fabricate matematerial-assisted elliptical cylindcial external cloak.
Preliminary behavior studies of edge localized modes on HL-2A
Authors: Liu Chun-Hua  , Nie Lin  , Huang Yuan  , Ji Xiao-Quan  , Yu De-Liang  , Liu Yi  , Feng Zhen  , Yao Ke  , Cui Zheng-Ying  , Yan Long-Wen  , Ding Xuan-Tong  , Dong Jia-Qi  , Duan Xu-Ru  ,   Center for Fusion Science, Southwestern Institute of Physics, Chengdu 610041, China
Published: December 2020

The edge-localized modes (ELMs) are often excited in an H-mode plasma, and they are helpful for cleaning the H-mode plasma to sustain a steady state for a longer time by controlling plasma density and exhausting impurities, but energy and particles carried by ELM burst will badly damage the first-wall of fusion device, thus the characteristics of and the control and mitigation of ELM are studied necessarily prior to the basic operational regime operating on ITER. ELMs of different perturbation amplitudes are observed experimentally on HL-2A tokamak. The frequency of small perturbation amplitude ELM decreases with the increase of net heating power, and it is about 300-400 Hz, and energy loss induced by per ELM is usually less than 3% of the plasma energy. The small ELM is type Ⅲ ELM. While for large (type-I) ELM, besides that the energy loss induced by an ELM is generally more than 10%, they also exert an obvious perturbation on other plasma parameters, such as plasma current and electron density, and the tELM may be longer than 30 ms. ELM precursors are poloidally asymmetric, which can be measured by Mirnov probes on the low field side, but not on the high field side; the frequency of ELM precursors is about 45 kHz, and the longest precursors last approximately 10 ms prior to the ELM bursts.
Effect of electron temperature anisotropy on plasma-wall interaction in Hall thruster
Authors: Qing Shao-Wei  , E Peng  , Duan Ping  ,   Department of Electrical Engineering, Harbin Institute of Technology, Harbin 150001, China;,   Institute of Power Engineering, Chongqing University, Chongqing 400030, China;,   Department of Physics, Dalian Maritime University, Dalian 116026, China
Published: December 2020

To further reveal the physical mechanism of the saturated electron temperature which is about 50-60 eV in the discharge channel of Hall thruster, the effect of electron temperature anisotropy (ETA) on plasma-wall interaction in Hall thruster is studied by using a 2D3V particle-in-cell sheath dynamic model. Some important physical parameters such as electron-wall collision frequency, electron energy deposition at wall and the cooling effect of near-wall sheath on channel electron are calculated. Numerical results indicate that the influence of ETA on plasma-wall interaction is neglectable when electron temperature is low. However, when Te>24 eV, the ETA can significantly reduce electron-wall collision frequency, thereby reducing the electron energy deposition at wall and weakening the cooling effect of near-wall sheath on channel electron. It suggests that the anisotropy of electron temperature tends to increase the saturated electron temperature in the discharge channel of Hall thruster through remarkably weakening the interaction between channel electron and wall.
Wall cleanings for pre-treatment on EAST
Authors: Li Jia-Hong  , Hu Jian-Sheng  , Wang Xiao-Ming  , Yu Yao-Wei  , Wu Jin-Hua  , Chen Yue  , Wang Hou-Yin  ,   Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China
Published: December 2020

Wall cleaning has been used popularly on tokamaks to reduce impurities and fuel recycling. Since 2008, the plasma facing components of EAST have been all of graphite. Due to the special crystal structure of graphite, high outgassing rate and strong absorption of hydrogen gas are induced. The wall cleaning is in particular important for the pre-treatment before the plasma operation of the machine. In this article, we introduce the wall conditioning system on EAST, and study the removal efficiency of device baking and glow discharge cleaning in different working gases and at different operating parameters. The long duration baking and GDC cleaning in EAST notably reduce the wall outgassing, and impurity radiation. After the cleanings, plasma is easily obtained, which is beneficial for the plasma physics experiment.
Synthesis and photonics characteristics research of CdS:Cu 1D nanostructures
Authors: Liu Jun  , Zhou Wei-Chang  , Zhang Jian-Fu  ,   Northwest Institute of Nuclear Technology, Xi'an 710024, China;,   Micro-Nano Technology Research Center of Hunan University, Changsha 410082, China;,   School of Nuclear Science and Technology, Xi'an Jiaotong University, Xi'an 710049, China
Published: December 2020

One-dimensional (1D) Cu-doped CdS nanostructure is synthesized via the chemical vapor deposition. The growth mechanism of Cu-doped CdS nanoarchitecture is disclosed. Some novel photonic properties are discovered. The experimental results indicate that the preparation of Cu-doped CdS 1D nanostructure could be achieved by controlling the experiment conditions. With the effect of doped ions, the nanoarchitecture has different radiant spectra when it is excitated by lasers of different powers. Doping concentration is considered to be an evident factor to affect the position and relative power of the illuminant peaks but not to influence spectrum shapes evidently. The result may be conducible to extending the application of CdS nanoarchitectures in the research field of nanophotonics.
Ge and Nb co-doped TiO2 films with narrow band gap and low resistivity prepared by sputtering
Authors: Luo Xiao-Dong  , Di Guo-Qing  ,   Jiangsu Key Labortory of Thin Films, Department of Physics, Soochow University, Suzhou 215006, China
Published: December 2020

Ge and Nb co-doped anatase TiO2 films are prepared by using radio frequency magnetron sputtering. The structures, resistivities and band gap properties of the films, which depend on Ge and Nb doping amounts, sputtering power and annealing temperature, are discussed. It is found that the band gap and resistivity of TiO2 film can be simultaneously tailored by co-doping with Ge and Nb. With doping volume fractions of 6% Nb and 20% Ge, the resistivity of the film can be reduced from 104 Ω/cm to 10-1 Ω/cm, and the band gap from 3.2 eV to 1.9 eV. After annealing, the Ge and Nb co-doped TiO2 film shows not only a lower resistivity but also a stronger absorption for visible and infrared light. As a result, Ge and Nb co-doped TiO2 film with adjustable band gap and resistivity can be prepared with magnetron sputtering by choosing proper Ge and Nb doping amounts and annealing conditions.
First-principles study of N-doped and N-V co-doped anatase TiO2
Authors: Xu Jin-Rong  , Wang Ying  , Zhu Xing-Feng  , Li Ping  , Zhang Li  ,   Department of Mathematics and Physics, Anhui University of Architecture, Hefei 230601, China;,   School of Physics and Technology, Nanjing Normal University, Nanjing 210097, China
Published: December 2020

The ground state atomic configurations and electronic structures of anatase TiO2, N-doped TiO2 and N-V co-doped TiO2 are studied by the projector augmented wave method and the generalized gradient approximation plus U (Hubbard correction) (GGA+U) based on the density functional theory. The results indicate that the volume of cell is slightly larger and the ground state configuration has no change significantly for N-doped TiO2, but the symmetry of cell is broken and the position of V atom is more close to N atom after co-doping with N and V. The band gap of anatase TiO2 is calculated to be 3.256 eV, which is in agreement with experimental value (3.23 eV). When N is doped, the gap is reduced by more than 0.4 eV. but for N-V co-doped system, the gap reduces to 2.555 eV. Moreover, the acceptor level and donor level, which can be formed between the valence band maximum and the conduction band minimum because of co-doping with N and V, are more favorable to the separation of photoelectron-hole pairs and reduce the rate of recombination. Therefore, the co-doping of anatase TiO2 with N and V can effectively improve the photocatalytic performance of anatase.
Analysis of the light absorption enhancement in polymer solar cell with TiO2 optical spacer
Authors: Li Guo-Long  , Li Jin  , Zhen Hong-Yu  ,   Ningxia Key Laboratory of PV Materials, Ningxia University, Yinchuan 750021, China;,   State Key Laboratory of Modern Optical Instrumentation, Zhejiang University, Hangzhou 310027, China
Published: December 2020

The thickness of the active layer is limited by its low carrier mobility in the polymer solar cell composed of the blend bulk-heterojunction formed by conjugated polymer as donor material and fullerene as acceptor material, which can affect the light absorption in the polymer solar cell. TiO2 inserted into polymer solar cell as optical spacer can redistribute the electromagnetic field inside the device and enhance the light absorption of it. In this paper, light intensity and absorption inside the devices with different thicknesses of P3HT:PCBM layer and TiO2 layer are calculated based on transfer matrix method. Theoretical analysis shows that inserting 10 nm TiO2 into the device can increase 16.3% light absorption, simultaneously thinning the active layer by 25 nm and the thickness of active layer will not apparently reduce the dissociation rate of the excitons. With the device structure of ITO (100 nm)/PEDOT:PSS (40 nm)/P3HT:PCBM/TiO2/LiF (1 nm)/Al (120 nm), the optimal thicknesses of the active layer and TiO2 are 75 nm and 10 nm respectively, which is confirmed by the experimental results from the devices with three different structures.
Synthesis and magnetic properties of CoFe2O4 and MnFe2O4 nano composites
Authors: Gao Ruo-Rui  , Yu Wei  , Fei Chun-Long  , Zhang Yue  , Xiong Rui  , Shi Jing  ,   Key Laboratory of Artificial Micro- and Nano-Structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan 430072, China
Published: December 2020

Highly dispersed granular nano-composite material of CoFe2O4 and MnFe2O4 with an average size of 20 nm is synthesized through thermal decomposition. The soft-hard magnet exchange-spring effect is observed in magnetization measurements at low temperatures, and is found to be strongly affected by the temperature of the reaction and the composition ratio between soft and hard magnetic phases. Magnetization measurements at different temperatures show that at 20 K, the saturation magnetization increases significantly, which is attributed to the freezing of the spin-glass like state at the surface of the nano-composite material. A Henkel Plot measurement on our sample shows that for the dispersed composite material of CoFe2O4 and MnFe2O4, the dipole interaction is dominant among magnetic interactions.
A band Jahn-Teller effect in the martensitic phase transition of the Heusler alloy Mn2NiGe
Authors: Luo Li-Jin  , Zhong Chong-Gui  , Dong Zheng-Chao  , Fang Jing-Huai  , Zhou Peng-Xia  , Jiang Xue-Fan  ,   School of Science, Nantong University, Nantong 226007, China;,   Jiangsu Provincial Key Laboratory of Advanced Functional Materials, Changshu Institute of Technology, Changshu 215500, China
Published: December 2020

The changes of crystal structure, magnetic structure, electronic structure in the martensitic phase transition for magnetic shape memory alloy Mn2NiGe are calculated by first-principles method. The results show that in the martensitic phase transition for Mn2NiGe, there is produced a Jahn-Teller distortion, in which the c-axis becomes longer but a-axis and b-axis turn shorter, forming an elongated octahedral geometry. There is a significant change in magnetic moment for Mn ion in the centre of octahedron, but a little change happens to the Ni and Ge ions that are regarded as a ligand. The energy levels of eg and t2g are split by redistributing the density of states for d electrons and so opening a pseudogap near the fermi energy due to lattice distortion.
The influence of central metal Ga atom on triplet-state dynamics and singlet oxygen generation of Corrole
Authors: Shao Wen-Li  , Lin Yong-Feng  , Lin Feng-Can  , Peng Kai-Mei  , Zhang Lei  , Wang Hui  , Liu Hai-Yang  , Ji Liang-Nian  ,   State Key Laboratory of Optoelectronics Materials and Technologies, Sun Yat-Sen University, Guangzhou 510275, China;,   Department of Chemistry, South China University of Technology, Guangzhou 510641, China;,   School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou 510275, China
Published: December 2020

In this paper, the triplet-state transient absorption spectra and the dynamic processes of 5, 15-bis (pentafluorophenyl)-10-(phenyl) corrole, 5, 10, 15-tris (pentafluorophenyl) corrole and their corresponding free-base corroles are measured by the laser flash photolysis technique. The measurement results show that the wavelength region of triplet-state absorption of these corroles ranges from 440 nm to 540 nm and the absorption peak wavelength of each sample is 450 nm. The insertion of metal Ga atom into corrole ring shortens the triplet lifetime of corrole under anaerobic condition and makes triplet lifetime longer under aerobic condition, which reduces oxygen quenching rate. The steady-state emissions of singlet oxygen of these corroles are also measured by the infrared luminescence method. The results show that the insertion of metal Ga atom makes singlet oxygen quantum yield of corroles slightly decrease. The results indicate that the heavy atom effect generated from metal Ga atom influences the triplet-state dynamics and singlet oxygen generation of corrole.
Research of the navigation accuracy for the X-ray pulsar navigation system
Authors: Wang Peng  , Zhao Bao-Sheng  , Sheng Li-Zhi  , Hu Hui-Jun  , Yan Qiu-Rong  ,   State Key Laboratory of Transient Optics and Photonics, Xi'an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi'an 710119, China;,   University of Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

In order to improve the navigation accuracy of the X-ray pulsar navigation system, in this paper we propose a constant fraction timing method based on the low-pass filter to measure the arrival time of the X-ray pulse in X-ray pulsar navigation. According to the technical scheme, the timing accuracies and dead times of original peaking timing and the improved constant fraction timing are measured. Experimental results indicate that the timing accuracy and the dead time of the peaking timing system are 18 ns and 4750 ns, the timing accuracy and the dead time of the constant fraction timing system are 0.78 ns and 105 ns. The timing accuracy and the dead time of constant fraction timing system are significantly improved compared with those of the peaking timing system. In the X-ray pulsar navigation system, the cumulative pulse profile of the X-ray pulse is constructed in the two different timing systems through measuring the arrival time of the X-ray photon. Experimental results indicate that compared with using the peaking timing system, the cumulative pulse profile of the X-ray pulse using the improved constant fraction timing system is improved obviously, therefore, the navigation accuracy could be improved by using the constant fraction timing system.
Restraining parasitic interference fringe phenomenon in detection imaging through the medium with inclined angle
Authors: Diao Qi-Long  , Huang Chun-Lin  ,   School of Electronic Science and Engineering, National University of Defense Technology, Changsha 410073, China
Published: December 2020

Some periodic interference fringes due to medium with inclined angle are found in the echo image when the medium plate is inclined in the penetrating experiment. These interference fringes have serious influence on the imaging result of the interesting target. The study indicates that the interference fringes are caused by the reflected waves, which mainly come from the surface and below layer of the medium plate. To analyze the interference fringe phenomenon, a point source model is constructed in the paper, and the expression of the spacing between the adjacent interference fringes is derived. When the factor about antenna is taken into account, the pyramid horn near-field model is constructed. Based on it, the accurate electromagnetic simulations are performed. The results of the commercial software CST and MATLAB calculation both confirm the analysis about the interference fringes and the relation with the inclined angle of the medium plate. From the expression of the thin medium, the spacing between the adjacent interference fringes is related to incline degree of the medium. Controlling the influence factors of the spacing between fringes can restrain the interference fringe phenomenon in order to improve the target resolving power and imaging quality.
Fractional Brownian motor and its directed transport
Authors: Bai Wen-Si-Mi  , Peng Hao  , Tu Zhe  , Ma Hong  ,   Department of Mathematics, Sichuan University, Chengdu 610064, China
Published: December 2020

Adopting power function as a damping kernel function of generalized Langevin equation, flash ratchet potential as a potential field, the model of fractional Brownian motor is derived in the case of overdamped condition. With the memory effect of fractional derivatives, the motion characteristics of the particle in overdamped fractional Brownian motor are discussed. Inverse transport which is not seen in conventional Brownian motor, is found in an overdamped fractional Brownian motor. The influences of fractional order and noise density on transport speed are discussed separately. For a fixed fractional order, stochastic resonance appears in transport speed as noise density varies. For a fixed noise density, transport speed will oscillate as the fractional order varies, that is, multipeak generalized stochastic resonance takes place.
Breaking chaotic direct sequence spreading spectrum communication systems using DM-UKF chaotic fitting method
Authors: Gan Lu  , Xiong Bo  ,   University of Electronic Science and Technology of China, Chengdu 611731, China
Published: December 2020

In this paper, a dual model unscented Kalman filter chaotic fitting breaking method is proposed to break chaotic direct sequence spread spectrum communication systems in the cases of low spreading factor, low signal-to-noise ratio or severe multipath fading. Based on the characteristic that the range of information symbol is a finite set, the proposed algorithm fits the original chaotic signal through different filters which work in parallel. The fitting errors are used to choose the optimum matching filter, thus to estimate the information symbols. Furthermore, an error-controlling-factor is introduced to increase the distance of model based tracking errors, which can not only facilitate the information extracting process, but also reduce the influence of noise and multipath fading. Theoretical analysis and simulation results prove that the proposed algorithm is superior to the existing breaking method.
Study on the control of spiral waves in coupled excitable media
Authors: Zhou Zhen-Wei  , Chen Xing-Ji  , Tian Tao-Tao  , Tang Guo-Ning  ,   College of Physics and Technology, Guangxi Normal University, Guilin 541004, China
Published: December 2020

The control of spiral waves in three-layer coupled excitable media is studied by using the Bär model. The bidirectional coupling between adjacent layers is adopted. We use planar waves generated by a local periodic signal added to the second layer to eliminate spiral waves in the media. The numerical results show that when the couplings among three layer media meet some conditions the spiral waves in the media can be controlled. The control of spiral waves may be achieved by using the complementary coupling strategy. The interaction between planar wave and low-frequency spiral wave can produce high-frequency spiral wave, leading to failure to eliminate spiral waves. There exists an optimal drive width. Both larger and smaller drive width may need larger coupling strength between the first and third layers. The control results depending on the control opportunity are observed. We hope that this study will contribute to the design of the implantable cardioverter defibrillator.
Design and realization of grid multi-scroll chaotic circuit based on current conveyers
Authors: Wang Chun-Hua  , Yin Jin-Wen  , Lin Yuan  ,   College of Information Science and Engineering, Hunan University, Changsha 410082, China
Published: December 2020

In this paper, we propose method of generating grid multi-scroll chaotic attractors with the positive-type second generation current conveyors (CCII+). Firstly, a three-dimensional grid multi-scroll chaotic system is presented. Some basic dynamical properties are studied. Furthermore, we construct the saturation functions with current output and design the chaotic system with series structure by using current conveyers. In the whole design the port parasitic parameters of current conveyers are taken into considerations. By analyzing we could learn that the circuit can work in a higher frequency range. Finally, the effectiveness of this method is verified by circuit implementation.
Analysis of community evaluation criterion and discovery algorithm of weighted complex network
Authors: Lü Tian-Yang  , Xie Wen-Yan  , Zheng Wei-Min  , Piao Xiu-Feng  ,   College of Computer Science and Technology, Tsinghua University, Beijing 100084, China;,   Audit Research Institute, National Audit Office, Beijing 100830, China;,   College of Computer Science and Technology, Harbin Engineering University, Harbin 150001, China
Published: December 2020

The clustering of nodes is an important feature of complex network. Previous researches mainly focus on community discovery in unweighted network, with little attention paid to the weighted network because of the complexity of weighted network. The community discovery of the weighted network is believed to be a much more difficult task. In this paper, we perform a study on the effectivenesses of community evaluation criterion and the performances of the existing discovery algorithms. First, we summarize three classical community evaluation criterions of weighted network, and analyze their effectivenesses according to a simulated noisy dataset, which has different community sizes, densities and local characteristics. Second, we adopt five datasets to compare the performances of three typical community discovery algorithms. The study shows that the existing criterions encounter difficulties in evaluating the basic community structure and in evaluating the weighted community with complex structure, and the generalization ability of the typical community discovery algorithm of weighted network is unsatisfactory.
Relation of containment capacity with phase composition, density and Vickers hardness of simulated waste forms Gd2-xNdxZr2O7(Nd=An(Ⅲ), 0≤ x ≤ 2.0)
Authors: Duan Tao  , Lu Xi-Rui  , Liu Xiao-Nan  , Zhu Wen-Kun  , Huang Ye-Ju  ,   Fundament on Nuclear Waste and Environmental Security Laboratory, Southwest University of Science and Technology, Mianyang 621010, China;,   Laboratory for Extreme Conditions Matter Properties, Southwest University of Science and Technology, Mianyang 621010, China
Published: December 2020

In order to investigate the capability of Gd2Zr2O7 pyrochlore as a waste form for immobilizing trivalent actinides nuclides, Nd(Ⅲ) is used as an alternative substance for An(Ⅲ). The compounds in the system Gd2-xNdxZr2O7 (0≤ x ≤ 2.0) are synthesized at 1500 ℃ for 72 h by high temperature solid state reaction method, using Gd2O3 and ZrO2 powders as the raw materials. The phase, intensity, Vickers hardness and microcosmic shape are characterized by X-ray diffraction, Vickers hardness tester, scanning electron microscopy and so on. The results indicate that the phase of synthesized waste form with plate-shape keeps the phase of pyrochlore. The intensity of compound slightly decreases with the increase of the containment capacity value x, but it is above 5.76 g·cm-3. The value of Vickers hardness also decreases with the increase of x. The values of x and Vickers hardness are linearly related by HV=695.18636-162.64091 x (HV≥ 400 kg·mm-2).
The effect of energetic electron impact ionization on radiation ionization process of high-altitude nuclear explosion
Authors: Ouyang Jian-Ming  , Ma Yan-Yun  , Shao Fu-Qiu  , Zou De-Bin  ,   College of Science, National University of Defense Technology, Changsha 410073 China
Published: December 2020

The X-ray ionizations and atmospheric temporal evolutions of different altitude nuclear explosions at different distances are numerically simulated. The effects of energetic electron impact ionization on radiation ionization process are analyzed in this paper. It is concluded that the energetic electron impact ionization process is important for radiation ionization, and in the case of 1 kt equivalent explosion at 80 km, the electron density at 1.5 km distance from explosion center increases two orders because of the energetic electron impact ionization. In 5 μs the spectral energy distribution of energetic electrons varies with time, and the number density of energetic electrons decaying with electron energy will present an approximately negative exponential distribution. The peak time of electron density and the influence area of ionization increase with explosion altitude increasing. The ionization effect for 1 kt equivalent explosion at 80 km has an important influence on micro-wave communication in a 100 km range.
Influence of beam moving characteristics on smoothing effect of focal spot
Authors: Zhou Bing-Jie  , Zhong Zhe-Qiang  , Zhang Bin  ,   College of Electronics and Information Engineeering, Sichuan University, Chengdu 610064, China
Published: December 2020

The concept and physical model of "beam moving" are proposed. For the scheme of angular spectral dispersion, taking the sinusoidally phase-modulated pulse and the linearly chirped pulse for example, the properties of the transverse movement of chirped broadband beam are analyzed theoretically. The effects of the transverse moving speed, the moving cycle and the moving mode on the smoothing of focal spot are discussed in detail. The results show that the linearly chirped pulse could achieve better smoothing effect than the sinusoidally frequency-modulated pulse with the same bandwidth.
Tripartite quantum deterministic key distribution based on GHZ states
Authors: Zhou Nan-Run  , Song Han-Chong  , Gong Li-Hua  , Liu Ye  ,   Department of Electronic Information Engineering, Nanchang University, Nanchang 330031, China
Published: December 2020

By exploiting the entanglement properties of continuous variable quantum GHZ state, we propose a tripartite quantum deterministic key distribution, in which the key is generated from its amplitude and the phase can be used to test and verify the channel security. The existing quantum deterministic key distribution can only hand over deterministic key to one receiver in one communication. However, we always have to transmit deterministic key to more than one receiver in real life. The analysis results of information theory show that when the channel transmission efficiency is greater than 0.5, the proposed protocol can securely hand over the pre-deterministic key to two receivers simultaneously, and it can also be extended to multiparty quantum deterministic key distribution when preparing multiple entangled state, this will greatly improve the overall efficiency of the key transmission, furthermore, the continuous variable quantum GHZ state could have a higher channel capacity, so the protocol has the important practical significance.
Low-frequency acoustic absorption of viscoelastic coating with various shapes of scatterers
Authors: Lü Lin-Mei  , Wen Ji-Hong  , Zhao Hong-Gang  , Meng Hao  , Wen Xi-Sen  ,   Key Laboratory of Photonic/Phononic Crystals of Ministry of Education, National University of Defense Technology, Changsha 410073, China
Published: December 2020

The low-frequency underwater sound absorption phenomenon induced by the localized resonance in phononic crystal shows a promising application for the design of underwater acoustic absorption material in recently study. To further reveal the sound absorption mechanism and optimize the low-frequency underwater sound absorption characteristic, the viscoelastic coating embedded with various shapes of scatterer is investigated. In this paper, to shorten the computing time of the original finite element program and save the core memory, the conventional finite element method is simplified due to the symmetry of the lattice and the scatterers, then the simplified finite element method is validated by comparing the results of the simplified finite element method with those of the conventional finite element method. The relationship between the resonance mode described with the displacement contours of one unit cell at specified frequencies and the corresponding absorption spectrum is discussed in detail, which reveals briefly the sound absorption mechanism of the viscoelastic coating embedded with cylindrical scatterer. Finally, the shape effect of the scatterer on the sound absorption characteristics is investigated, spherical scatterers and the three cylindrical scatterers with different shapes but the same volume are considered. Further, the influence of the density of the core on acoustic absorption characteristic under an air backing is discussed. The results show that lower sound absorption properties can be deduced by adopting the cylindrical scatterers and reducing the radius of the base of circular cylindrical scatterer, and the absorption bandwidth can be improved by choosing the optimal scatterer material.