bluuebunny/crossref_metadata_2025 huggingface dataset:
Study of energy stability and perturbation in the Q-ball solutions of Klein-Gordon equation
Authors: Yan Jun  ,   Department of Physics, Sichuan Normal University, Chengdu 610066, China
Published: December 2020

The two-layer Q-ball solutions in the complex scalar field model are studied in this paper, and the Q-ball charge and energy are calculated in an analytical form. Meantime, the energy stability is analyzed, and the perturbative expression of Q-ball is obtained by means of Klein-Gordon equation. Moreover, the physical effect of Q-ball dark matter is also discussed.
High-efficient quantum state sharing via non-maximally five-qubit cluster state
Authors: Sun Xin-Mei  , Zha Xin-Wei  , Qi Jian-Xia  , Lan Qian  ,   School of Science, Xi’an University of Posts and Telecommunications, Xi’an 710061, China
Published: December 2020

In this paper we present a new scheme for quantum state sharing of an arbitrary unknown two-qubit state by using a non-maximally five-qubit cluster state as quantum channel. In this scheme, the non-maximally five-qubit cluster state is shared by a sender (Alice), a controller (Charlie), and a receiver (Bob), who does not need to introduce an auxiliary particle but only operates an appropriate unitary transformation. The sender introduces an auxiliary particle and makes orthogonal complete bases measurement, and the controller makes a single-particle projective measurement on his particle, then the quantum state sharing can be probabilistically realized.
Poisson survival model of quantum entanglement signaling network and fidelity analysis
Authors: Nie Min  , Zhang Lin  , Liu Xiao-Hui  ,   College of Communication and Information Engineering, Xi’an University of Posts and Telecommunications, Xi’an 710121
Published: December 2020

Quantum signaling states have decoherence because of the environment during the transmission. It causes signaling damage and thus will have impact on building high survivability quantum entanglement signaling network. In order to study the influence deeply, Poisson damage model of quantum signaling network is established. First, disaster magnitude is defined base on signaling fidelity. Second, average damage signaling quantum bits and survival function of quantum signaling network is put forward by basic quantum theory. At last, research on the signaling damage repair strategy and simulation is analyzed. Simulation results show that increasing of disaster magnitude will greatly reduce the signaling network survivability. However, increasing the nodes and controlling signaling damage caps may improve survivability. The repair strategy which costs small number of cycles can rapidly increase the signaling fidelity from 0.6 to 0.9 and the survival function of the signaling network from 0.4 to 0.9.
A phase space denoising method for chaotic maps
Authors: Lü Shan-Xiang  , Feng Jiu-Chao  ,   School of Electronic and Information Engineering, South China University of Technology, Guangzhou 510641, China
Published: December 2020

The spectra of chaotic maps are much wider than those of chaotic flows, and their overlapped regions with Gaussian white noise are much larger, thus the denoising method for chaotic flows is unsuitable for chaotic maps. Within a semi-blind analysing framework, the parameter estimating problem for chaotic systems can be boiled down to a least square evaluating procedure. In this paper we start with estimating the evolution parameters of chaotic maps by using a least square fitting method. After that, phase space reconstruction and projection operation are employed to get noise suppression for the observed data. The simulation results indicate that the proposed algorithm surpasses the extended Kalman filter (EKF) and the unscented Kalman filter (UKF) in denoising, as well as maintaining the characteristic quantities of chaotic maps.
Method of imaging performance deterioration anlysis and its experiment simulated high heating sapphire MW infrared window during near-hypersonic flight
Authors: Peng Zhi-Yong  , Wang Xiang-Jun  , Lu Jin  ,   MOEMS Education Ministry Key Laboratory of Tianjin University, Tianjin 300072, China;,   State Key Laboratory of Precision Measurement Technology and Instruments of Tianjin University, Tianjin 300072, China;,   Jinhang Institute of Technical Physics, Tianjin 300192, China
Published: December 2020

During supersonic flight, the heat radiation of aero-craft optical window has negative effect on infrared imaging performance. A computational model of radiance transmit route and radiation intensity was built in the paper. And the paper also gave the radiation emission model and infrared imaging model. The problem of heat radiance imaging was transform to the problem of optical computation. The simulation results showed that method proposed by the paper was effective to analysis the heat window radiation problem. An heating sapphire window experiment is designed to validate the simulation result. By subtraction between the deduced image based on model and experiment image, it is found that average error for each pixel is about 0.45. By analysis of experiment results, the infrared image contrast degree and Signal-to-Noise was reduced to about one third of the original ones. And the NETD of infrared system with heating window rose from 52 mK to 954 mK. The heating window radiation analysis model presented by the paper can effectively estimate aero-thermal effects on mid-wave infrared imaging system. The designed experiment developed a effective way to verify imaging system performance. And it is also much meaningful for optimal infrared spectral band selection, imaging parameter adjustment and the hot dome radiation suppression to reduce the image degradation.
Conformal invariance and conserved quantity for a variable mass holonomic system in relative motion
Authors: Wang Ting-Zhi  , Sun Xian-Ting  , Han Yue-Lin  ,   School of Science, Jiangnan University, Wuxi 214122, China;,   School of Electric and Information Engineering, Pingdingshan University, Pingdingshan 467002, China
Published: December 2020

Conformal invariance and conserved quantity for a variable mass holonomic system in relative motion have been studied. The definition and the determining equations of conformal invariance for a variable mass holonomic system in relative motion are given. The necessary and sufficient conditions that the system’s conformal invariance be of Lie symmetry are deduced. With the aid of a structure equation which the gauge function should satisfy, the system’s corresponding conserved quantity is obtained. Finally, an illustrative example is given to verify the results.
Study on the electromagnetic fields of an extended source over layered models
Authors: Qi You-Zheng  , Huang Ling  , Zhang Jian-Guo  , Fang Guang-You  ,   Key Laboratory of Electromagnetic Radiation and Sensing Technology Chinese Academy of Sciences Beijing 100190, China;,   University of Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

In practical applications of transient electromagnetic methods, irregularity of the transmitting loop or current waveform makes the source an extended one. Since neglect of the effect of the extended source will cause some errors in both forward modeling and data interpretation, it makes great sense to calculate the responses that take this effect into account. For a spatially extended source over layered medium, step response is firstly calculated and taken as the basic response, then principle of reciprocity and the integral of the second kind are used to propose a new method that can compute the response based on the coordinates of the loop. For an extended source in time, an improved step-function summation method is proposed to deal with the contradiction between the precision of result and consuming of time. Comparisons with the published work have proved the validity and accuracy of our methods. The effect of the traditional approximations of the extended source is also investigated and some analysis for the numerical results is presented for advanced usage.
Study on surface waves formed at the interface between linear dielectric and centrosymmetric photorefractive crystals
Authors: Feng Tian-Run  , Lu Ke-Qing  , Chen Wei-Jun  , Liu Shu-Qin  , Niu Ping-Juan  , Yu Li-Yuan  ,   Institute of Electronics and Information Engineering, Tianjin Polytechnic University, Tianjin 300387, China
Published: December 2020

We report localized surface waves at the interface between linear dielectric and centrosymmetric photorefractive (CP) crystals. Adjusting the values of the guiding parameter δ and the propagation constant b, we can easily get three types of surface waves: delocalized surface waves, shock surface waves, and localized surface waves. When the difference between b and δ exceeds a certain threshold value, the localized surface waves can form at the interface between linear dielectric and CP crystals. For positive δ values, the part of the energy of localized surface waves concentrated in the nonlinear CP crystals is always higher than that in the linear dielectric, and increases monotonically with b. The stability properties of the localized surface waves are investigated numerically and it is shown that they can be stable. In a given system, the orders and waveforms of localized surface waves are controlled by adjusting the variable parameters which determine the strength of nonlinear effects.
Dynamic process simulation of droplet spreading on solid surface by lattic Boltzmann method
Authors: Liu Qiu-Zu  , Kou Zi-Ming  , Han Zhen-Nan  , Gao Gui-Jun  ,   Taiyuan University of Technology, College of Mechanical Engineering Taiyuan 030024, China;,   Shanxi Province Mine Fluid Control Engineering Ttechnology Rresearch Center, Taiyuan 030024, China
Published: December 2020

Spray dust mechanism is to use spray to wet and reduce the coal mine dust. Based on lattice Boltzmann method, the dynamic behaviors of droplet spreading on solid surface are simulated numerically in consideration of the molecules reaction between fluid and solid. Results show that the spreading diameter and dynamic contact angle change exponentially with time. The relationship between droplet surface tension and maximum spreading diameter is determined; it is shown that the wettability of solid surface has a great influence on the maximum spreading velocity. All the above numerical results are in good agreement with the experimental and theoretical results reported in the literature. Moreover, the solid surface with high hydrophobicity is further investigated. It is found that the spreading contact angle can be less than 90° if the droplet surface tension is small enough, which agrees well with the theoretical formula. The simulation also shows that there occurs oscillations in the spreading process and retraction when the droplet spreads to its maximum.
Stability characteristics of thin film dewetting with insoluble surfactant
Authors: Li Chun-Xi  , Jiang Kai  , Ye Xue-Min  ,   Key Laboratory of Condition Monitoring and Control for Power Plant Equipment, North China Electric Power University, Baoding 071003, Hebei, China
Published: December 2020

Considering the process of insoluble-surfactant-laden film dewetting on a solid substrate, we have established the base state and disturbance evolution equations for the film thickness and interfacial surfactant concentrations based on the lubrication approximation. Transient growth analysis (TGA) was carried out to investigate the stability characteristics of evolution process, and the effects of intermolecular forces were discussed. Results indicate that the introduction of disturbance wave for k=1 is conducive to enhance the stability of film evolution, and the disturbance energy gradually decays; however, the effect changes unexpectedly with the increment of wave number: when k ≥ 2, the stability of dewetting process is deteriorated while disturbance energy grows by degrees and the film flow shows unstable characteristics. Thickening the initial film thickness can effectively improve the stability of film dewetting. Van der Waals force enlarges the disturbance on the film surface and leads to the decline of stability. Conversely, Born force and electrostatic force are propitious for the film evolving stably.
Plasmon effects on linear spectra related to heterogeneous electron transfer
Authors: Tan Zi  , Wang Lu-Xia  ,   Department of physics, University of Science and Technology Beijing, Beijing 100083, China
Published: December 2020

By considering the effect of molecular vibrational states, a system of dye semi-conductor coupled with metal nano-particle linear absorption spectra and its electron transfer dynamics are studied in dipole-dipole approximation. As the results of the coupling of metal nano-particle, a wider absorption spectrum and the enhancement of electron transfer have been achieved. Effects of nano-metal surface plasmons on the ultrafast heterogeneous electron transfer are discussed in detail.
Polarized Raman spectra of single crystal Bi2ZnOB2O6
Authors: Zhang Ji  , Zhang De-Ming  , Wang Di  , Zhang Qing-Li  , Sun Dun-Lu  , Yin Shao-Tang  ,   Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China;,   An Hui Xin Hua University, Hefei 230088, China
Published: December 2020

Polarized Raman spectra of single crystal Bi2ZnOB2O6 have been recorded in the spectral range 101600 cm-1 at room temperature. Factor group analysis was used to obtain the normal modes of vibration of the crystal. The Raman peaks under 300 cm-1 are assigned to external modes, which are related to the rotational and transitional movement of the [BiO6], [ZnO4], [BO4] and [BO3] groups. Compared with the vibrational spectra of the compounds referred, the satisfactory assignment of most of the high-energy modes to vibrations of Bi-O, B-O and Zn-O bonds can be achieved. In particular, the Raman high-frequency peak located at 1407 cm-1 is attributed to the B-O vibration in the [BO3] triangle.
Electrically-controlled nonlinear terahertz optical properties of graphene
Authors: Dong Hai-Ming  ,   Department of Physics, China University of Mining and Technology, Xuzhou 221116, China
Published: December 2020

In this paper, we present a detailed theoretical study of nonlinear terahertz optical properties of graphene in the presence of electric field and terahertz radiation field. The optical current is computed and investigated on the basis of quantum theory and semi-classical Boltzmann equations. It shows a large nonlinear terahertz response and the nonlinearity becomes larger with increasing electric field or decreasing terahertz frequencies. Moreover, it is found that the optical nonlinearity can be modified and controlled by electric fields.
Tuning surface plasmons in nanorod arrays with ultrasmall spacing
Authors: Lü Jiang-Tao  , Zhao Yu-Qian  , Song Ai-Juan  , Yang Lin-Juan  , Zhang Yang-Yu  , Liu Yan  , Gu Qiong-Chan  , Jiang Xiao-Xiao  , Ma Zhen-He  , Wang Feng-Wen  , Si Guang-Yuan  ,   School of Control Engineering, Northeastern University at Qinhuandao, Qinhuangdao 066004, China
Published: December 2020

In this work, we first investigate the optical properties of nanorod arrays with normal inter-rod spacing (>100 nm) and realize the tuning of nanorod localized surface plasma resonance (LSPR) by changing array parameters (e.g., periodicity). Then we filter our individual colors in the visible range using nanorod arrays with ultrasmall inter-rod spacing and ultrahigh density fabricated by electron beam lithography (EBL) and ion etching. The functional nanorod arrays developed in this work are compatible with current digital light processing technique, enabling screen with ultrasmall pixels which can find extensive applications in display and imaging.
Strain effect on the morphological instability of a circular island in heteroepitaxy
Authors: Wang Jing  , Feng Lu  , Hao Yi  , Zhao Yang  , Chen Zhen-Fei  ,   Tianjin Key Laboratory of Modern Engineering Mechanics, Tianjin 300072, China; Department of Mechanics, Tianjin University, Tianjin 300072, China
Published: December 2020

In this paper, the strain effect on the morphological instability of the circular island is studied in terms of the BCF (Burton, Cabera, Frank) model. We introduce strains into the BCF model under the Gibbs-Thomson condition and investigate the instability of the island due to the combined effect of the misfit strain, applied strain, deposition flux, line tension, and the far-field flux. Thus, we obtain the perturbation growth rate and the critical deposition flux. Results indicate that the misfit strain and the far-field flux tend to destabilize the growth of the island, and the line tension has a stabilizing effect. In addition, the larger island is more stable during the growth of the island. Up to the critical radius, as the misfit strain increases, the critical flux increases. When taking into account the applied strain, the negatively applied strain stabilizes the growth of the island and decreases the critical flux. These results are almost opposite to the case of the positive strain. This could potentially provide on important theoretical basis for controlling the growth and stability of the films.
Coupling analysis of electrocardiogram and electroencephalogram based on improved symbolic transfer entropy
Authors: Wu Sha  , Li Jin  , Zhang Ming-Li  , Wang Jun  ,   Image Processing and Image Communications Key Lab., Nanjing Univ. of Posts & Telecomm., Nanjing 210003, China;,   College of Physics and Information Technology, Shaanxi Normal University, Xi’an 710062, China;,   Department of Gastroenterology, The No. 1 Hospital of Xi’an, Fen Rd 30, the South Street, Xi’an 710002, China
Published: December 2020

Exploration of the coupling relationship in dynamical system has always been a hot topic of many scholars at home and abroad, the traditional symbolic dynamics analysis method may lead to the results from the serious effect of non-stationary time series. This paper employs coarse graining extraction based on research of original transfer entropy. Through theoretical and experimental analysis, we find that the results of transfer entropy have different distribution trend under different extraction conditions in the coupling analysis of electroencephalogram and electrocardiogram. We choose the best effect of signal data extraction method and apply it to the later application analysis. Furthermore, this paper proposes improvement on the method of time series symbolization, using dynamic adaptive segmentation method. The experimental results show that the whether waking period or sleeping stage, coupling between electroencephalogram and electrocardiogram is more significant when using improved symbolic transfer entropy algorithm. It is also better to capture the dynamic information of the signal and the change of complexity of system dynamics, which is more conductive to clinical testing in practical application and has a better effect on the analysis of non-stationary time series.
Stability theorem and control of fractional systems
Authors: Hu Jian-Bing  , Zhao Ling-Dong  ,   School of Electronics and Information, Nantong University, Nantong 226019, China;,   College of Information Science and Technology, Donghua University, Shanghai 201620, China
Published: December 2020

The stability theorem of fractional systems is the basis of controlling fractional nonlinear systems. The theorem of fractional nonlinear systems is proved by a new approach in this paper. The results show that the theorem is applicable not only to the fractional nonlinear autonomous system, but also to the fractional nonlinear nonautonomous system. Several examples are analyzed by the theorem, and simulations are carried out, whose results show the effectiveness of the theorem.
Analysis of dynamical behaviors in a nonlinear switching circuit system
Authors: Zhang Xiao-Fang  , Zhou Jian-Bo  , Zhang Chun  , Bi Qin-Sheng  ,   Faculty of Civil Engineering and Mechanics, Jiangsu University, Zhenjiang 212013, China
Published: December 2020

A nonlinear circuit model with periodic switching is established. The fold bifurcation and Hopf bifurcation sets of the subsystems are derived via the analysis of the relevant equilibrium points as well as the stabilities. Complex dynamical behaviors caused by periodic switching in various equilibrium states of subsystems are investigated. The results show that there exist two types of destabilizing cases, i.e., period-doubling bifurcation and saddle-node bifurcation, in the variation of periodic solution to the switching system with parameter, leading to different forms of chaotic oscillations correspondingly. Furthermore, by analyzing the the phase trajectory and its corresponding bifurcation, the mechanisms for different types of oscillations are presented, which can explain some phenomena of the switched dynamical system.
Effect of inhomogeneous distribution of ion channels on collective electric activities of neurons in a ring network
Authors: Wu Xin-Yi  , Ma Jun  , Xie Zhen-Bo  ,   Department of Physics, Lanzhou University of Technology, Lanzhou 730050, China
Published: December 2020

In this paper, we investigate the evolution and transition of collective electric activities of neurons in a ring network, induced by inhomogeneous distribution of ion channels. The local kinetics is measured by Morris-Lecar under voltage coupling type. In the numerical studies, the effect of inhomogeneous distribution of ion channels is simulated by changing the conductance in ion channels embedded in the membrane, and the potential mechanism is discussed. The effect of diversity of conductance between calcium and potassium ions on the activating of the adjacent neurons, and the dependence of developed travelling wave on the coupling intensity, are investigated in detail. The activating and waking up the nonexcitable or quiescent neurons with type I and type II excitability, are investigated, respectively. The numerical results confirm that the adjacent neurons are activated and the stable travelling wave is developed in the ring network of neurons when the conductance of calcium ions is increased beyond a certain threshold or the conductance of potassium ions is reduced below another threshold; while the propagation of the travelling wave could be slowed down or suppressed when the conductance of calcium ions is reduced or the conductance of potassium ion is increased. The development or emergence of travelling wave and propagation are greatly dependent on the increase of conductance of calcium ions and the decrease of potassium conductance.
A joint compression and encryption scheme for color JPEG image
Authors: Xiao Di  , Xie Yi-Jun  ,   Key Laboratory of Dependable Service Computing in Cyber Physical Society, Ministry of Education, College of Computer Science, Chongqing University, Chongqing 400044, China
Published: December 2020

To research the encryption algorithm for color joint photographic expert group (JPEG) image, by comprehensively choosing the selective encryption and the joint compression and encryption, an encryption algorithm combining with spatial domain and frequent domain for color JPEG image is proposed. The 8×8 blocks are first diffused on spatial domain, then the edge-detection method is utilized to find out the significant blocks containing abundant details. After encrypting all the direct current coefficients, part of alternating current (AC) coefficients in significant blocks are chosen to be encrypted. Finally the information about marking the significance of the blocks is embedded into AC coefficients for transmission. Theoretical analyses and experimental results show that the proposed algorithm is compatible with JPEG format. The cipher image has good visual quality and uniform color distribution. The algorithm possesses huge key space, strong key-sensitivity and good security.
Effect of self-injected electrons driven by paralleled drive electron bunches
Authors: Zhang Feng  , Huang Shuo  , Li Xiao-Feng  , Yu Qin  , Gu Yan-Jun  , Kong Qing  ,   Key Laboratory of Applied Particle Beam, Ministry of Education, Institute of Modern Physics, Fudan University, Shanghai 200433, China;,   Physics Department, Fudan University, Shanghai 200433, China
Published: December 2020

In the case of wake field acceleration driven by charged particle bunches, many researchers focused on adjusting parameters such as magnitude, shape and electrical properties to amplify the maximum energy which drives electrons. Comprehensively considering the existing studies, in the paper we propose a new method of acceleration in which paralleled bunches are used to excite plasma wake field and trap self-injected electrons. It is proved to be more efficient than using single drive beam. With 2.5D PIC code, the driven electrons accelerated by paralleled bunches are found to possess the advantages of acceleration in longer distance, higher energy and better quasimonoenergy. Moreover, a bunch of backflow electrons is observed in the bubble, which makes self-injected electrons well collimated.
Cavitation bubble in compressible fluid subjected to traveling wave
Authors: Yao Xiong-Liang  , Ye Xi  , Zhang A-Man  ,   College of Shipbuilding Engineering, Harbin Engineering University, Harbin 150001, China
Published: December 2020

With the wave equation, the boundary integral equation with considering compressibility is deduced. Then the motion characteristics and stability of cavitation bubble driven by traveling wave are obtained. The influences of wave frequency, amplitude and initial phase on the motion of cavitation bubble are analyzed. The results show that the motion stability is enhanced with the increase of drive frequency or the reduction of drive amplitude. With appropriate frequency and amplitude, the jet will be formed at the anaphase of contraction, and the direction is the same as that of the traveling wave. With the consideration of compressibility, the time for once pulsation of the cavitation bubble is shortened and the pulsation amplitude is reduced, correspondingly the jet tip velocity and the inner pressure also decrease. With the increase of drive frequency or the reduction of drive amplitude, the pulsation amplitude and intensity of jet decrease. The variation of initial phase will lead to the changes of the initial motion state of cavitation bubble and the jet strength.
Electromagnetic pulse emission produced by Z pinch implosions
Authors: Dan Jia-Kun  , Ren Xiao-Dong  , Huang Xian-Bin  , Zhang Si-Qun  , Zhou Shao-Tong  , Duan Shu-Chao  , Ouyang Kai  , Cai Hong-Chun  , Wei Bing  , Ji Ce  , He An  , Xia Ming-He  , Feng Shu-Ping  , Wang Meng  , Xie Wei-Ping  ,   Key Laboratory of Pulsed Power, Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

In this paper, we represent the radiation characteristics of electromagnetic pulse generated by Z pinch implosion. Magnetic energy which couples with motions of metallic wire arrays or solid liners driven by Z pinch can radiate away. Theoretical results indicate that the radiation power of electromagnetic pulse is determined by both load current and implosion trace. Experiments are carried on primary test stand facility at Institute of Fluid Physics where a current rising to 7 MA in (10%–90%) 65 ns is used to drive a wire array Z pinch. The measured load current and implosion trace show that the Z pinch can deliver about 1 GW, 10 ns full width, 20–70 MHz central frequency, broadband electromagnetic pulse with an energy conversion efficiency of 10-7. Parameters of electromagnetic pulse are much smaller than those of X-ray with a power of 50 TW and an energy of 0.5 MJ. In the approximation of weak relativistic case, the power of electromagnetic pulse which is proportional to sixth power of load current, dramatically increases with current increasing. Soft X-ray radiation is an important channel for dissipating a considerable fraction of energy provided by facility. The results presented here demonstrate that electromagnetic pulse emission in the case of higher load current can cause significant damage to diagnostic devices. Moreover, intense electromagnetic pulse produced by this method may have many potential applications.
Macroscopic model of internal discharging in polymer under electron beam irradiation
Authors: Quan Rong-Hui  , Han Jian-Wei  , Zhang Zhen-Long  ,   Department of Astronautics, Nanjing University of Aeronautics and Astronautics, Nanjing 230016, China;,   National Space Science Center, China Academy of Sciences, Beijing 100190, China
Published: December 2020

Internal charging effect and discharging effect in a dielectric material are one of the key factors threatening the spacecraft safety. Most of the spacecraft charging models could calculate only the voltage variation and electric field distribution in the spacecraft internal charging process, without estimating the consequence of discharging, such as the magnitude of voltage drop and discharging current. In this article, we present a combined model which could calculate both the charging effect and the discharging effect on polymer. The model is verified by the experimental results, and it shows that the residual voltage after discharging and the pulse width of discharging current grow with the increase of polymer resistivity. The magnitude of discharging current is determined by the breakdown electrical field.
Properties of 5d atoms doped boron nitride nanotubes：a first-principles calculation and molecular orbital analysis
Authors: Zhang Zhao-Fu  , Geng Zhao-Hui  , Wang Peng  , Hu Yao-Qiao  , Zheng Yu-Fei  , Zhou Tie-Ge  ,   College of Electronic Information and Optical Engineering, Nankai University, Tianjin 300071, China
Published: December 2020

The geometry, electronic structure and magnetic property of boron nitride nanotube (BNNT), whose boron/nitride atoms are substituted by 5d atoms (B5d or N5d), are investigated by first-principles calculations based on density functional theory. The pure-BNNT and BNNT with boron vacancy (VB) or nitrogen vacancy (VN) are also investigated for comparison. Results show that the local symmetry of B5d system is similar to C3v, however the N5d system exhibits a large geometric deviation from C3v. The total magnetic moments of doped systems are different from each other, and B5d system present a strong regularity. The total density of states is presented, where impurity energy levels exist. The impurity energy levels and total magnetic moment can be explained by the molecular orbital theory under C3v symmetry.
Thermite reaction of Al and α-Fe2O3 at the nanometer interface：ab initio molecular dynamics study
Authors: Tang Cui-Ming  , Zhao Feng  , Chen Xiao-Xu  , Chen Hua-Jun  , Cheng Xin-Lu  ,   Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, China;,   Department of Physics and Mathematics, Sichuan University of Science and Engineering, Zigong 643000, China;,   Key Laboratory of National Defence Science and Technology for Shock Wave and Detonation Physics, Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

Based on the density function theory, thermite reaction between Al and α-Fe2O3 at temperature 2000 K in canonical ensemble is investigated by ab initio molecular dynamics. In the simulation, with the increasing of the time, the number of the Fe–O bond decreases, while the numbers of Al–O bonds and Fe–Fe bonds increase. At the same time, the total charge quantity of Fe ions decreases and the total charge quantity of Al ions increases as time increases. In the Al/Fe2O3 thermite reaction, the redox reaction is observed, Al atoms are oxidized and the Fe ions are reduced. And then the rupture of Fe–O bonds and the formation of Al–O bonds happen at the interface. Whole redox reaction is completed in about 3 ps.
The effect of out-of-plane strain on the electrocaloric performances of P(VDF-TrFE) vertical heteroepitaxial film
Authors: Zhang Hang-Bo  , Wu Hua-Ping  , Zhou Ting  , Zhang Zheng  , Chai Guo-Zhong  ,   Key Laboratory of Special Purpose Equipment and Advanced Manufacturing Technology (Zhejiang University of Technology), Ministry of Education/Zhejiang Province, College of Mechanical Engineering, Hangzhou 310014, China;,   College of Civil Engineering and Architecture, Zhejiang University of Technology, Hangzhou 310014, China
Published: December 2020

Considering the boundary conditions of 1-3-type P(VDF-TrFE) composite ferroelectric film, the effect of out-of-plane strain on the electrocaloric performances of vertical heteroepitaxial film is calculated by the nonlinear thermodynamic theory. The results indicate that the out-of-plane strain can effectively regulate the ferroelectric and electrocaloric performances including the polarization, electrocaloric coefficient and adiabatic temperature change under the action of vertical electric field. In a wide temperature range, the vertical heteroepitaxial film can present higher adiabatic temperature change than the pure P(VDF-TrFE) film by controlling the out-of-plane strain. This indicates that the vertical composite heteroepitaxial film with excellent electrocaloric performances will have potential applications in the microelectronic devices such as micropowers, optical communication diodes and infrared sensors.
Properties of luminescence and scintillation of Eu-doped high gadolinium glass
Authors: Tang Chun-Mei  , Shen Ying-Long  , Sheng Qiu-Chun  , Liu Shuang  , Li Wen-Tao  , Wang Long-Fei  , Chen Dan-Ping  ,   Research and Development Center of High Power Laser Components, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China;,   University of Chinese Academy of Sciences, Beijing 100049, China;,   Shanghai Institute for Science of Science, Shanghai 200235, China
Published: December 2020

Eu (1 wt%) doped 15SiO2-25B2O3-30Al2O3-30Gd2O3 oxide glasses are prepared by high-temperature melt-quenching method in air and reduced atmosphere, respectively. The properties of scintillation and photoluminescence of the two samples are compared. When the samples fabricated in reduced atmosphere are excited by the X-ray and 395 nm violet light, a 450–550 nm blue-green light beam from Eu2+ and a 615 nm red light beam from Eu3+ are obtained. The intensity ratios between Eu3+ and Eu2+ are obviously different under different excitation sources. The intensity ratio under the excitation of the 395 nm violet light is 0.02 while it increases to 1.37 under the X-ray excitation. By analyzing the phonon sideband spectra of the samples, it is found that the Eu3+ ions around the former of Si are completely reduced into Eu2+ ions, while only part of Eu3+ ions around the former of B and Al are reduced into Eu2+ ions. Further investigation about the scintillation mechanism indicates that the sensitization of Gd and the energy transfer of Eu2+→Eu3+ near the formers of B and Al increase the scintillation performances of Eu3+ ions in the reduced glass samples.
Influence of space charge effect on Nottingham effect in thermal field emission
Authors: Zuo Ying-Hong  , Wang Jian-Guo  , Fan Ru-Yu  ,   Northwest Institute of Nuclear Technology, Xi’an 710024, China;,   Department of Engineering Physics, Tsinghua University, Beijing 100084, China
Published: December 2020

High current electron beam emitting from a thermal field emission cathode has an intense space charge effect. In order to investigate the mechanism for the influence of space charge effect on Nottingham effect in thermal field emission, the results of Nottingham effect with and without space charge effect at different work functions and various applied electric fields are obtained numerically on the basis of the theoretical analyses of space charge effect and Nottingham effect. The results demonstrate that the space charge effect has a significant influence on the steady electric field at the cathode surface, and thus the effect of space charge on Nottingham effect is not ignorable. When the work function is in a range of 3.0–4.52 eV and the applied electric field is in a scope of 3×109–9×109 V/m, the average energy delivered per electron in thermal field emission is in a span of 0–2.5 eV larger than that in the case without space charge effect, and the higher the cathode temperature or applied electric field, the larger the difference between them is. The average energy delivered by per electron emitting from cathode is observed to nonlinearly decrease with the increasing of applied electric field when the space charge effect is included. When the cathode temperature is high, the cooling effect in Nottingham effect can be intensified as the gap distance of diode increases.
Effect of a-Si：H interface buffer layer on the performance of hydrogenated amorphous silicon germanium thin film solar cell
Authors: Liu Bo-Fei  , Bai Li-Sha  , Zhang De-Kun  , Wei Chang-Chun  , Sun Jian  , Hou Guo-Fu  , Zhao Ying  , Zhang Xiao-Dan  ,   Key Laboratory of Photo-Electronic Thin Film Devices and Technology, Key Laboratory of Optoelectronic Information Technology of Ministry of Education, Institute of Photo Electronics Thin Film Devices and Technology of Nankai University, Tianjin 300071, China
Published: December 2020

In the light of the open circuit voltage and fill factor reduction resulting from band gap discontinuities and high defect densities at interfaces when more germanium is mixed into the intrinsic layer of hydrogenated amorphous silicon germanium solar cell, the insertion of a-Si:H buffer layer with proper band gap into PI interface not only mitigates band gap discontinuities and interface recombination, but also improves the electric field distribution by reducing the defect densities at PI interface, thus the collection efficiency of a-SiGe:H solar cell is enhanced. By inserting a-Si:H buffer layer into IN interface and designing band gap profile along the a-SiGe:H intrinsic layer further, the 8.72% conversion efficiency of single junction a-SiGe:H solar cell is achieved when only Al back reflector is added as back contact.
A navigation search model based on subnet of maximum controllability
Authors: Xiao Yan-Dong  , Lao Song-Yang  , Hou Lü-Lin  , Bai Liang  ,   College of Information Systems and Management, National University of Defense Technology, Changsha 410073, China
Published: December 2020

In this paper, we propose a concept of subnet of maximum controllability based on the model of network controllability, and set up the navigation search model based on the subnet of maximum controllability, called NMSMC. The strategy of adding links that is based on the subnet of maximum controllability is to solve, with the minimum cost, the terminating search, the problem that arises from no way for particles to search in the directed network. Based on the subnet of maximum controllability to deploy navigation nodes,the search time of the whole network can be made close to the average shortest path of the navigation network,which the number of navigation nodes is only 2% of the total nodes. The experimental results of the ER and SF networks show that the search efficiency is strongly correlated with the network controllability. The better the controllability, the less the adding links are, which can lead to the fact that the more the navigation nodes are distributed in the network, the more the search efficiency of the network can be enhanced.
Stochastic resonance of a memorial-damped linear system with natural frequency fluctuation
Authors: Xie Wen-Xian  , Li Dong-Ping  , Xu Peng-Fei  , Cai Li  , Jin Yan-Fei  ,   Department of Applied Mathematics, Northwestern Polytechnical University, Xi'an 710072, China;,   Department of Mechanics, Beijing Institute of Technology, Beijing 100081, China
Published: December 2020

The stochastic resonance is investigated in the generalized Langevin equation with exponential memory kernel subjected to the joint action of internal noise, external noise and external sinusoidal forcing. The system is converted into three-dimensional Markovian Langevin equations. Furthermore, using the Shapiro-Loginov formula and the Laplace transformation technique, the exact expressions of the first moment and the steady response amplitude are obtained. The research results show that with the variations of external sinusoidal force frequency and the parameters of memory kernel and external noise, the system presents bona-fide stochastic resonance, conventional stochastic resonance and stochastic resonance in a broad sense under the condition of Routh-Hurwitz stability. In addition, the stochastic resonance can be weakened as the memory time increases. Moreover, the numerical results of power spectrum of system are in agreement with the analytic results.
A method of weak target detection based on the sea clutter
Authors: Xing Hong-Yan  , Zhu Qing-Qing  , Xu Wei  ,   Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Key Laboratory of Meteorological Observation and Information Processing of Jiangsu Province, College of Electronic and Information Engineering, Nanjing University of Information Science and Technology, Nanjing 210044, China
Published: December 2020

According to the phase space reconstruction theory of nonlinear system, we propose a prediction method of support vector machine based on genetic algorithm. Using the improved autocorrelation method and Grassberger-Procaccia algorithm to determine the time delay and embedding dimension of chaotic signal, the phase space reconstruction is implemented. The penalty coefficient and the kernel function parameter of support vector machine are optimized by genetic algorithm. Combined with support vector machine, single-step prediction model of the chaotic sequence is set up, so we can detect the weak signal in chaos from the prediction error (including the transient signal and periodic signal). Lorenz attractor and the data from the McMaster IPIX radar sea clutter database are used in the simulation. The proposed method can effectively detect the weak target from chaotic signal. When the signal-to-noise ratio is -89.7704 dB in the chaotic noise background, by using the new method the root mean square error can be reduced by two orders of magnitude, reaching 0.00049521, while the conventional support vector machine can reach only 0.049 under the condition of -54.60 dB.
Full three-dimensional simulations of optimized active pixel detector for ionizing particle detection
Authors: Hu Hai-Fan  , Wang Ying  , Chen Jie  , Zhao Shi-Bin  ,   College of Information and Communication Engineering, Harbin Engineering University, Harbin 150001, China;,   Institute of Microelectronics of Chinese Academy of Sciences, Beijing 100029, China
Published: December 2020

In this paper, a double epitaxial and high energy implant (DEI) is proposed to improve the performance of charge collection and radiation hardness. Three-dimensional process procedure and physical level simulation are presented. The results show that the internal distributions of electric potential and electric field are improved; the seed point pixel collected charge increases about 70% and reduces the collected time to 64%. In addition, the DEI structure increases the collecting efficiency in a radiation range from 1012 to 1015 cm-2as compared with the standard monolithic active pixel sensors.
Dynamics for the reaction O+DCl→OD+Cl
Authors: Xu Xue-Song  , Yang Kun  , Sun Jia-Shi  , Yin Shu-Hui  ,   Department of Physics, Dalian Maritime University, Dalian 116026, China
Published: December 2020

With the quasi-classical trajectory method the stereodynamics of the O+DCl→OD+Cl reaction on the ground potential energy surface is investigated. The characteristic of calculated integral cross-section is consistent with that of the non-energy barrier reaction path on the potential energy surface, which implies that the title reaction is a typical exothermic reaction. The obtained differential reaction cross-section shows that the products tend to both forward and backward scattering, and the forward scattering is stronger than the backward one. So we can infer that the reaction follows the indirect reaction mechanism that has been verified by the randomly abstractive reaction trajectories. The distribution curves of P(θr) and 2(J'· K)> reflect that the degree of rotational alignment of the product OD first increases and then decreases with collision energy increasing. The product rotational angular momentum vector J' is aligned along the y-axis direction but is oriented along the positive direction of y-axis at higher collision energy. With the increase of the collision energy the rotation mechanism of the product molecules transits from the “in-plane” mechanism to the “out-of-plane” mechanism.
Effect of source parameters on polarization characteristics of electromagnetic beam propagating in atmospheric turbulence
Authors: Li Cheng-Qiang  , Wang Ting-Feng  , Zhang He-Yong  , Xie Jing-Jiang  , Liu Li-Sheng  , Guo Jin  ,   State Key Laboratory of Laser Interaction with Matter, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China;,   University of Chinese Academy of Sciences, Beijing 100049, China;,   Key Laboratory of Optical System Advanced Manufacturing Technology of Chinese Academy of Sciences, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China
Published: December 2020

According to the theory of beam spreading and taking electromagnetic Gaussian Shell-model beam as an object of research, the change in its spectral degree of polarization is studied by numerical analysis. Based on the numerical results, the mechanism that governs the change in polarization of an electromagnetic beam on propagation is discussed. The results show that the beam spreading of two components of an electromagnetic beam results in the change in polarization of beam directly, and the beam spreading is determined by source parameters and atmospheric turbulence. The difference between beam spreading of two components induced by coherence leads to the change in polarization in free space. The change in degree of polarization is influenced by source parameters and turbulence on propagation in atmosphere. The result is similar to that in free space over relatively short distance, which is mainly governed by source parameters. With the enhancement of turbulence over a sufficiently long distance, the change in polarization in atmosphere is different from that in free space.
Coherence of X-ray in the third synchrotron radiation source
Authors: Qi Jun-Cheng  , Ye Lin-Lin  , Chen Rong-Chang  , Xie Hong-Lan  , Ren Yu-Qi  , Du Guo-Hao  , Deng Biao  , Xiao Ti-Qiao  ,   Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China;,   Graduate University of Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

Since the third generation synchrotron radiation source came into service, the X-ray techniques which relate to coherent property have quickly developed and been widely used. Typically, X-ray phase contrast imaging has become a conventional imaging method. The X-ray techniques, such as coherence scattering, coherent diffraction imaging, and photon correlation spectroscopy, have received more attention and shown unique superiority in the field of high spatial and time resolution. So quantifying the coherent property of X-ray source is meaningful for those novel X-ray techniques. In this article, based on the Talbot self-imaging phenomenon, the spatial coherent property and the scale of X-ray source of X-ray imaging and biomedical application beam line in Shanghai synchrotron radiation facility are measured. The results show that when the photon energy is 33.2 keV, the spatial coherence length is 8.84 μm and source size is 23 μm in the vertical direction, and the test result is in agreement with the theoretical value.