bluuebunny/crossref_metadata_2025 huggingface dataset:
Super-resolution ghost imaging via compressed sensing
Authors: Li Long-Zhen  , Yao Xu-Ri  , Liu Xue-Feng  , Yu Wen-Kai  , Zhai Guang-Jie  ,   Key Laboratory of Electronics and Information Technology for Space Systems, Center for Space Science and Applied Research, Chinese Academy of Sciences, Beijing 100190, China;,   University of Chinese Academy of Sciences, Beijing 100190, China
Published: December 2020

Achieving high resolution images is of great importance in ghost imaging. We present a super-resolution image reconstruction algorithm with sparse measurements based on the theory of compressed sensing and the prior knowledge of the point spread function of the ghost imaging system. A computational ghost imaging experimental setup with a digital mirror device is built to verify the effect of this algorithm on increasing the resolution of the ghost imaging system. In addition, we compare the result with that from the traditional ghost imaging algorithm. The experiments show that we can obtain super-resolution images by this algorithm with the sparse measurements. This approach can break through the Rayleigh limit of the imaging system and obtain super-resolution images.
Propagation characteristics of seismic waves in shallow soil with the unsaturated three-phase poroelastic model
Authors: Ding Wei  , Wu Wen-Wen  , Wang Chi  , Wu Zhi-Qiang  ,   Deptment of Precision Mechanical Engineering, Shanghai University, Shanghai 200072, China
Published: December 2020

In order to study the mechanism of acoustic landmine detection, the propagation characteristics of acoustically coupled seismic waves in shallow soil are investigated. Based on the porosity and compressibility of shallow soil, the influences of parameters including soil porosity and water saturation on the propagation properties of seismic wave are discussed with the model of seismic waves in unsaturated three-phase porous medium. The calculation results show that under the given parameters, the propagation velocity and attenuation coefficient of seismic wave increase with the increase of acoustic frequency. The propagation velocities of longitudinal waves and those of transverse waves respectively decrease and increase with the increase of soil porosity. In addition, the propagation characteristics of acoustically coupled seismic waves become complicated with the increase of water saturation. The feasibility of the analysis method is discussed by comparing the calculation results with the experimental data published previously. As a result, a theoretical foundation is provided for the acoustic-to-seismic coupling mechanism and its application in the study of acoustic resonance landmine detection.
Characteristics of micro fine copper particles impact damping
Authors: Ye Yang  , Wang Shu-Lin  ,   School of Energy and Power Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China;,   School of Materials Science and Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China
Published: December 2020

Impact damping has been widely used in machine tools, robots, turbine machineries, aircrafts, and launch vehicles. Introducing micro fine particles into impact dampers may bring additional irreversible energy loss such as particle size reduction and plastic deformation for the damping, and carve out a new way to control the motion. For this purpose we use copper particles with an average size of 50 μm in ball impact dampers installed on a cantilever subjected to sinusoidal vibration within 96-hour impacting, and test the damping characteristics. We show that the response of the primary system can be divided into three stages, i.e., increasing, then deceasing, and increasing again. This dynamic feature reflects the deformation behaviors of the micro copper particles in different stages. In the first stage, the copper particles may display elastic behavior, and the sub-harmonic vibration of the steel ball may return part of the energy back to the primary system and enhance the response. In the second stage, the copper particle is forced into its yield point and the plastic deformation exhausts the energy and response of the system decline. In the third stage, hardening effect of the copper particles occurs and the response of system increases again. Our results may be significant to passively control the vibrations and material deformation.
A continuum constitutive model and computational method of explosive detonation
Authors: Zhou Hong-Qiang  , Yu Ming  , Sun Hai-Quan  , Dong He-Fei  , Zhang Feng-Guo  ,   Institute of Applied Physics and Computational Mathermatics, Beijing 100094, China
Published: December 2020

Some basic thermodynamic relationships are used to develop a theroretical framework for modeling the detonation in explosives, on the assumption that explosive and detonation product are in a local thermodynamic equilibrium state, i.e., their pressures and temperatures are identical. Using this framework, a continuum constitutive model for explosive detonation is composed of a group of ordinary differential equations including the state equations of explosive and its product, simple mixing law, reaction rate equation and energy conservation equation, which are easily solved by a mature computational method such as trapezoidal rule. A group of nonlinear constitutive equations in a generalized Maxwellian form describe the relationship among the time evolution rates of pressure and temperature, the strain rate, and the chemical reaction rate. Coefficients appearing in the constitutive equations are determined only by parameters of the explosive and the product through using simple mixing rule. The continuum constitutive model and the corresponding computational method are verified by simulating the detonation behaviour of PBX9404 impacted by high velocity Cu flyer, and in the simulation the JWL equation of state for unreacted explosive and detonation product and the two-term Lee-Tarver reaction rate equation are adopted.
Effect of periodic grooving topography on dynamics of Insoluble surfactant-laden thin film flow
Authors: Li Chun-Xi  , Chen Peng-Qiang  , Ye Xue-Min  ,   Key Laboratory of Condition Monitoring and Control for Power Plant Equipment, North China Electric Power University, Baoding 071003, China
Published: December 2020

Targeting the flowing of insoluble surfactant-laden film over topography substrate, the lubrication theory is adopted to derive the evolution equations of thin liquid film thickness and interfacial surfactant concentration. The flowing characteristics of the film on topography surfaces, and the influence of topography structure are examined based on the numerical simulation with PDECOL code. The results show that when the thin film of insoluble surfactant flows over periodic grooving topography, the depression appears at the negative step, while the ridge is shaped at the positive step, both of which increase gradually with time going by. Compared with the case of the flat base, the surfactant-laden film spreading speed is enhanced. Increasing the groove depth or reducing the groove steepness leads to the increase of the rupture possibility of the film. Improving the groove width promotes the film flowing. The decrease of the steepness can cause the film to form a ridge feature before entering into the first groove. Gravity has the opposite effects on the up-hilling and down-hilling processes of liquid film flow, which causes the flow stability to deteriorate. Conjoining pressure induced by intermolecular forces can accelerate the film, giving rise to a notable dewetting phenomenon, while disjoining pressure has an adverse effect.
Leakage current characteristics of the insulating sample under high-energy electron irradiation
Authors: Li Wei-Qin  , Liu Ding  , Zhang Hai-Bo  ,   School of Automation and Information Engineering, Xi'an University of Technology, Xi'an 710048, China;,   Key Laboratory for Physical Electronics and Devices of the Ministry of Education, Department of Electronic Science and Technology, Xi'an Jiaotong University, Xi'an 710049, China
Published: December 2020

The leakage current characteristics of an insulating sample under high-energy electron beam irradiation are simulated by a numerical model with taking into account the electron scattering, transport, trapping and self-consistent field.The leakage current is measured by using a detection platform. Results show that under the continuous electron beam irradiation, the total electron yield decreases evidently; because of electron transport, the sample near the surface is positively charged weakly and its interior is negatively charged strongly; some electrons are transported downward, forming the electron beam induced current and the leakage current under the long time irradiation. Under the irradiation, the leakage current increases to a stable level gradually. The leakage current decreases with the increase of sample thickness, but it increases with beam energy and current.
Investigation on the magnetic and magnetocaloric properties of PrNi2
Authors: Huang Yi-Jia  , Zhang Guo-Ying  , Hu Feng  , Xia Wang-Suo  , Liu Hai-Shun  ,   Department of Physics, College of Science, China University of Mining and Technology, Xuzhou 221008, China
Published: December 2020

The magnetic properties of some magnetic materials are influenced by the exchange interaction between magnetic ions and the spin fluctuations of magnetic ions. By use of the exchange interaction-effective field including the spin fluctuations of magnetic ions Hm= n0(1+γ T +β eω T)M, the Zeeman splitting of crystal field energy levels of Pr3+ ions in PrNi2 and the variation of the magnetic moments with the applied field in a temperature range of 3.8 K≤ T ≤ 30 K are calculated. The thermal variation of the reciprocal susceptibility of Pr3+ ions is calculated as well for the applied magnetic field H=5000 Oe. The calculated results are in good agreement with the experimental data. The magnetic entropy changes are obtained theoretically in a magnetic field range of 0H<50000 Oe, and the results are similar to those reported in the literature. It is indicated that the exchange interaction-effective field containing the spin fluctuations is applicable not only to the ferrimagnetic crystals, but also to the paramagnets.
On-chip clocking for exchange-interaction-based nanomagnetic logic circuits
Authors: Zhang Ming-Liang  , Cai Li  , Yang Xiao-Kuo  , Qin Tao  , Liu Xiao-Qiang  , Feng Chao-Wen  , Wang Sen  ,   College of Science, Air Force Engineering University, Xi'an 710051, China
Published: December 2020

Nanomagnetic logic has the advantages in low power, non-volatility, and room temperature operation, however, low power on-chip clocking is the requirement of its integration. An on-chip clocking structure for a nanomagnetic logic circuit using exchange interaction is proposed in this work. This scheme is to use the Oersted field generated by current-carrying copper wire to magnetize ferromagnetic film cladding and then to switch the magnetization orientation of nanomagnets by the exchange interaction between magnetic layers. Simulation results demonstrate that the proposed scheme can reduce the power dissipation by 5/6 and the marginal spray field by 2/3 compared with the ferromagnetic yoked clocking that uses the external field to switch the magnetization. Therefore, it can reduce the power consumption and the risk of crosstalk. In addition, micromagnetic simulation verifies that nanomagnetic array laid on the proposed clocking can work functionally.
Infrared radiation dynamic response and parametric analysis for silicon solar cell using photocarrier radiometry
Authors: Liu Jun-Yan  , Qin Lei  , Song Peng  , Gong Jin-Long  , Wang Yang  , A. Mandelis  ,   School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001, China;,   Center for Advanced Diffusion Wave Technologies (CADIFT), Mechanical and Industrial Engineering, University of Toronto, Toronto, Ontario MS5 3G8, Canada
Published: December 2020

An analytic mathematical model of modulated laser-induced minority carrier density wave of silicon solar cells is developed, and light-induced carrier recombination radiation luminescence method (photocarrier radiometry (PCR)) is employed to detect the doping concentration, impedance and carrier transport parameters. The double knee characteristics of frequency domain response curve are investigated, and in a small ac signal case, the equivalent circuit topology structure of a solar cell is constructed. Through simulation analysis based on minority carrier density wave mathematical model, the effects of doping concentration, resistance and carrier transport parameters on the PCR frequency domain response are investigated. Donor/acceptor concentration, shunt resistance and carrier transport parameters of Si solar cell are obtained by PCR frequency-scanning experiments and multi-parameter fitting. The results show that the first knee position of PCR-detected large-area solar-cell frequency domain response curve is determined by the capacitive effect. The simplified mathematical model can be used to quantitatively describe and determine the doping concentration, shunt resistance and carrier transport parameters of silicon solar cell.
Optical model raciprocity of disk resonator excitated by tapered fiber
Authors: Guo Ze-Bin  , Tang Jun  , Liu Jun  , Wang Ming-Huan  , Shang Cheng-Long  , Lei Long-Hai  , Xue Chen-Yang  , Zhang Wen-Dong  , Yan Shu-Bin  ,   Key Laboratory of Instrumentation Science and Dynamic Measurement, Ministry of Education; Science and Technology on Electronic Test and Measurement Laboratory, North University of China, Taiyuan 030051, China
Published: December 2020

Optical resonator with high Q value can be used as a core component of the resonator optic gyro, with which the miniaturization and integration would be achieved. The coupling system composed of the disk cavity which is made by traditional micro-electro-mechanical system process and the tapered fiber which is drawn by melting method. When the disk cavity is coupled with the fiber at different places of the tapered region, by swapping input and output there is observed the deviation in the output transmission spectrum, also the resonant frequency, coupling efficiency and the Q value are changed, i.e., the non-reciprocity phenomenon appears. Then the distribution characteristics of the tapered fiber evanescent field are simulated with Rsoft software. The reason of the non-reciprocity is analyzed theoretically. According to the statistics of the output data when the disk cavity is coupled with the fiber at different places of the tapered region, it is found that the non-reciprocity can be eliminated effectively when the coupling happens at the center of the fiber tapered region. And this finding can be used to suppress the non-reciprocity noise produced by the coupling system composed of tapered fiber and resonant cavity in the resonator optic gyros application.
Pattern transfer and molecular chain orientation modulation by soft template during the nanoimprint lithography
Authors: Lu Nai-Yan  , Weng Yu-Yan  ,   Center for Soft Condensed Matter Physics and Interdisciplinary Research and College of Physics, Optoelectronics and Energy, Soochow University, Suzhou 215006, China;,   State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi 214122, China
Published: December 2020

The templates for the nanoimprinting are fabricated usually through a series of steps, such as E-beam lithography, E-beam deposition, liftoff and reactive ion etching. Any mistake during these steps would lead to the failure of the fabrication, so the template is always expensive and difficult to make. Under this circumstance, it is really important to find an effective way to build the template. In this report, the patterned photoresist layer is used as a mother set of the pattern definition of the soft template polydimethylsiloxane. The grating structure of conjugated polymer poly (9,9-dioctylfluorene) film is successfully obtained by this template in the nanoimprinting process. In addition, we also find the anisotropy of molecular chain distribution. Both the transmission electron microscope diffraction pattern and the polarized absorption spectrum are used to prove that this anisotropy is induced by the molecular chain alignment, which would be really helpful in future applications in organic emission equipment. Moreover, this result is also applicable to the poly (9,9-dioctylfluorenyl-2,7-diyl)-alt-co-(1,4-benzo-2,1',3-thiadiazole) film system.
Numerical analysis on multi-armed spiral patterns in gas discharge system
Authors: Bai Zhan-Guo  , Li Xin-Zheng  , Li Yan  , Zhao Kun  ,   College of Sciences, Hebei University of Science and Technology, Shijiazhuang 050018, China
Published: December 2020

The process of formation or transformation of multi-armed spiral patterns in gas discharge system is investigated numerically by using H.-G. Purwins model with three components. The parameter space is obtained though analyzing the influence of system parameters on system space, where a stable spiral appears. Besides, the formation mechanism and spatiotemporal characteristics of spiral pattern are studied. In addition, the evolution process of pattern from simple hexagon to spiral wave is numerically simulated, and various kinds of spirals are obtained (including two-armed, three-armed, four-armed, five-armed, six-armed, and seven-armed spirals). It is found that the stable spiral only survives in Turing-Hopf space, which is the result of interaction between Turing mode and Hopf mode. Furthermore, the spiral tips constantly rotate for various spiral patterns, and the velocity increases with the number of spiral arm increasing. For the influences of perturbation and boundary conditions, the multi-armed spiral pattern can lose one arm and become a new spiral in the rotating process. In conclusion, the numerical simulation results are in good agreement with those obtained in gas discharge experiment.
Indoor pseudolite relative localization algorithm with kalman filter
Authors: Liu Yang-Yang  , Lian Bao-Wang  , Zhao Hong-Wei  , Liu Ya-Qing  ,   Department of Electronics Engineering, Northwestern Polytechnical University, Xi'an 710072, China
Published: December 2020

In the indoor pseudolite positioning system, the effect of the clock offset always leads to a large error in the positioning result. To reduce the effect of the clock offset, a relative localization algorithm for the indoor environment is proposed. In this paper, firstly, the Kalman positioning algorithm is used to obtain the coarse baseline. The model of the indoor relative localization and its operation are shown. Using the Kalman filter, the pseudorange double difference is smoothed by the carrier phase double difference. Then, the accurate baseline and the accurate positioning result of the receiver could be obtained. In order to predict the next state precisely, the Kalman corrected result is replaced by the accurate result. The experimental results show that the proposed algorithm has a good localization accuracy and the positioning error is less than 20 cm.
Research on drought in southwest China based on the theory of run and two-dimensional joint distribution theory
Authors: Zuo Dong-Dong  , Hou Wei  , Yan Peng-Cheng  , Feng Tai-Chen  ,   Department of Physics, Yangzhou University, Yangzhou 225002, China;,   Laboratory for Climate Studies, National Climate Center, China Meteorological Administration, Beijing 100081, China;,   College of Atmospheric Sciences, Lanzhou University, Lanzhou 730000, China
Published: December 2020

Based on the standardized precipitation index data of 89 meteorological stations in southwest China (Sichuan Province, Yunnan Province, Guizhou Province, Chongqing) during 1961-2010, the probability and interval time were analyzed by employing the theory of run and the Copula function. The droughts with duration less than 4 months and the severity less than 3 account for 80% of all the droughts in southwest China. Drought types are mainly light within a month, moderate within a month, severe within a season and severe within inter-seasons. The frequency of occurring of drought with a duration less than 3 months and the severity less than 1 is higher in the eastern and western areas, and the central region has higher frequencies of occurrence of drought with a duration greater than 3 months and with severity greater than 1.5. Return periods of drought in eastern and western areas are longer than that of central region. More obvious spatial difference appears with longer duration and greater severity. The probability differences of the same drought type in different climatic types are within 0.05, indicating that there is no wide-range fluctuation in the occurrence probabilities of all the drought types as the time goes on.
Generalized dislocated lag projective synchronization of fractional chaotic systems with fully uncertain parameters
Authors: Li Rui  , Zhang Guang-Jun  , Yao Hong  , Zhu Tao  , Zhang Zhi-Hao  ,   Science College, Air Force Engineering University, Xi'an 710051, China;,   School of Life Science and Technology, Xi'an Jiaotong University, Xi'an 710049, China
Published: December 2020

In order to improve the security of secure communication combined with the generalized dislocated projective synchronization and lag projective synchronization, a new generalized dislocated lag projective synchronization (GDLPS) is investigated. This paper takes the fractional order Chen system and L system as examples. for the parameters of the two systems are uncertain, based on the fractional stability theory and adaptive control method, the nonlinear controller and parameter update laws are designed for the GDLPS between the two chaotic systems with uncertain parameters. Under the controller and parameter update laws, GDLPS of the two uncertain parameters chaotic systems is achieved and all uncertain parameters of the drive system and response system are identified. Theoretical analyses and numerical simulation show that this method is feasible and effective.
Structure and stability of Ti2Bn (n=1-10) clusters: an ab initio investigation
Authors: Wang Zhuan-Yu  , Kang Wei-Li  , Jia Jian-Feng  , Wu Hai-Shun  ,   School of Material and Chemistry Science, Shanxi Normal University, Linfen 041004, China
Published: December 2020

Structures and stabilities of Ti2Bn (n=1-10) clusters have been systematically investigated by using the density-functional theory B3LYP method and ab initio CCSD(T) method. It is found that the ground state structures of the Bn clusters are substantially modified by doping two Ti atoms. Ti2Bn clusters have very clear growth patterns, namely to form bipyramid. All the most stable Ti2Bn can be visualized as bipyramids with the two Ti atoms located at the two apexes. Ti2B6, Ti2B7 and Ti2B8 are confirmed to be the magic number clusters based on the analysis of the second-order difference of energies. The dissociation energies, vertical ionization potentials and vertical electron affinities of Ti2Bn isomers are discussed. Ti2B6 cluster is found to be stable both kinetically and thermodynamically.
Vector analysis of the coherent anti-Stokes Raman scattering signals generated under the tightly focused condition
Authors: Li Ya-Hui  , Liang Run-Fu  , Qiu Jun-Peng  , Lin Zi-Yang  , Qu Jun-Le  , Liu Li-Xin  , Yin Jun  , Niu Han-Ben  ,   College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China;,   Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, Shenzhen 518060, China;,   School of Physics and Optoelectronic Engineering, Xidian University, Xi'an 710071, China
Published: December 2020

In a coherent anti-Stokes Raman scattering (CARS) microscope, when samples with different shapes and dimensions are excitated by collinearly introduced and tightly focused Gaussian beams, the microscopic structure will be determined by the spatial distributions of generated CARS signals. Therefore, we build a theoretical model for CARS signals from spherical sample under the tightly focused condition. The intensity and phase distributions of tightly focused linear polarization Gaussian beams are analyzed with vector wave equations. The vector wave equation of CARS signals is derived from Green's function. The far-field CARS radiation patterns of spherical scatters with different diameters are simulatively calculated. Theoretical analysis and simulative calculation results show that the intensities of forward and backward CARS signals from the small spherical sampler are similar. The images with high contrast can be obtained by backward detection method from an objective with a high numerical aperture. For big spherical samplers, intensities of CARS signals are greatly increased. The emission direction is mainly concentrated in a spatial angle. The forward CARS signals can be effectively collected by an objective with low numerical aperture.
A molecular dynamics study on adhesive contact processes of surfaces with nanogrooves
Authors: Si Li-Na  , Wang Xiao-Li  ,   School of Mechanical Engineering, Beijing Institute of Technology, Beijing 100081, China
Published: December 2020

The adhesive contact processes between a rigid spherical tip and substrates with nanogrooves of different sizes have been investigated with a large-scale molecular dynamics simulation method. Influences of the surface grooves on the load-displacement curves, the attractive forces in the loading/unloading processes, and material transfer have been discussed. Results show that compared with the contact between a tip and a smooth surface, the attractive force range becomes larger in the loading process, accompanied by several jumps of the load, and the maximum attractive forces both in the loading and unloading processes are smaller. When the groove depths are the same, the maximum attractive forces in the loading and unloading processes decrease gradually with the increase of the groove width. However, when the groove width becomes close to the contact diameter between the tip and the smooth surface, the maximum attractive force would increase slowly, tending to be close to the case of smooth surface. When the groove width is kept the same, the maximum attractive force in the loading process decreases with the increase of the groove depth, while the maximum attractive force in the unloading process is almost unchanged.
Plasma-based multistage virtual cathode radiation
Authors: Su Dong  , Deng Li-Ke  , Wang Bin  ,   China Electronics Technology Group Corporation 26th Reserch Institute, Chongqing 400060, China;,   College of Electronic Engineering, Chongqing University of Posts and Telecommunications, Chongqing 400065, China
Published: December 2020

A novel electromagnetic (EM) radiation regime, the plasma-based multistage virtual cathode radiation model is proposed. Recent study indicates that, as an electron beam passes through a high-dense ion background, due to the cooperation of the ion background and the modulation of the virtual cathode formed at the focusing point, a multistage virtual cathode can be formed. Further studies show that the electrons reflected at different stages of the virtual cathode will come into oscillation, and the EM radiation will be excited, which is different from the betatron emission in an ion channel. As an example, a beam-ion channel system bound in a cylindrical cavity is studied by using particle in cell simulation. It is confirmed that a multistage virtual cathode is formed and EM radiation is induced. Finally, the characteristics of the radiation are discussed in the present paper.
First-principles study on the effect of Ge-doping on the conductivity of InI
Authors: Wang Yong-Zhen  , Xu Zhao-Peng  , Zhang Wen-Xiu  , Zhang Xin  , Wang Qian  , Zhang Lei  ,   School of Information Science and Engineering, Key Laboratory for Special Fiber and Fiber Sensor of Hebei Province, Yanshan University, Qinhuangdao 066004, China
Published: December 2020

The conductivities of InI with different concentrations of Ge-doping have been investigated by the ultra-soft pseudopotential approach of the plane-wave based on the density functional theory under the same condition. Models of the In1-xGexI (x=0, 0.125, 0.25) with In atoms substituted by different fraction of Ge are set up. The optimized structural parameters, total electron density of states, and energy band structures of Ge heavily doped In1-xGexI semiconductors at low temperature are calculated. Results show that the volumes are slightly reduced and the total energies are increased in the In1-xGexI systems and that the systems become instable. As the concentration of Ge increases, the electronic mobility decreases, but the relative number of electrons jumping to the conduction band increases, and the resistivity and the minimum optical band gap increase at the same time, which is beneficial to improving the performance of nuclear detection in the system.
First-principles study on the effects of Zn-segregation in CuΣ5 grain boundary
Authors: Meng Fan-Shun  , Li Jiu-Hui  , Zhao Xing  ,   School of Science, Liaoning University of Technology, Jinzhou 121001, China
Published: December 2020

The atomic and electronic structures of a Cu grain boundary with segregated Zn have been calculated by the first-principles method based on density functional theory and the effect of Zn segregation on Cu grain boundary is also analyzed. Results show that Zn is segregated to the Cu grain boundary in the way of substitution. Both Cu and Zn have the similar bonding characteristic with their neighbors, which are metallic bonds with a little covalentlike component. The Cu grain boundary with segregated Zn has strengthened the cohesion across the boundary slightly as compared with the clean Cu grain boundary because a small amount of charge accumulation is found between Zn and near neighboring Cu atoms due to the segregation of Zn. Grain boundary with segregated Zn would be fractured between Zn and Cu atoms because the d orbit of Zn is much more localized during the tensile test, resultsing in the weakness of Zn–Cu bond.
Effect of oxygen implantation on microstructural and optical properties of ZnTe:O intermediate-band photovoltaic materials
Authors: Zhen Kang  , Gu Ran  , Ye Jian-Dong  , Gu Shu-Lin  , Ren Fang-Fang  , Zhu Shun-Ming  , Huang Shi-Min  , Tang Kun  , Tang Dong-Ming  , Yang Yi  , Zhang Rong  , Zheng You-Dou  ,   School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, China;,   Department of Electronic Materials Engineering, Research School of Physics and Engineering, the Australian National University, Canberra 2601, Australia
Published: December 2020

Group Ⅱ-VI and Ⅲ-V highly mismatched alloys are promising material systems in the application of high efficiency intermediate-band solar cell (IBSC), however, the key issues including band engineering of intermediate band still remain challenging. In this study, ZnTe:O alloys have been produced by isoelectric oxygen implantation into ZnTe single crystal, and the influences of implantation on the microstructural and optical properties of ZnTe:O have been investigated in detail. It is found that a proper dose of oxygen ions can lead to a compressive strain in the lattice and induce the formation of intermediate band located on the energy level of ～ 0.45 eV below the conduction band. While a high dose of oxygen ions causes ZnTe surface layer to become amorphous and enhances the deep level emission around 1.6 eV, which is related to Zn vacancies. Results of resonant Raman and time-resolved photoluminescence spectra indicate that implantation induced intermediate band is related to the localized exciton emission bound to oxygen isoelectric trap, and the associated photo excited carriers have a relatively long decay time. This suggests that the reduction of lattice distortion and alloy disorder may be needed for converting localized states of the intermediate band into extended states, which is crucial to realize high efficiency ZnTe:O based IBSCs.
First-principles study on stability and electronic properties of MC and Mn+1ACn phases
Authors: Yang Jian-Hui  , Chen Yan-Xing  , Wu Li-Hui  , Wei Shi-Hao  ,   College of Teacher Education, Quzhou University, Quzhou 324000, China;,   College of Materials Science and Chemical Engineering, Quzhou University, Quzhou 324000, China;,   Department of Microelectronic Science and Engineering, Ningbo University, Ningbo 315211, China
Published: December 2020

Investigation of the stability and electronic properties of a series of MC compounds and classic MAX phases, Mn+1ACn (M=Sc, Ti, V, Cr, and Mn; A=Al, Si, P, and S; n=1, 2, and 3), contributes to finding the intrinsic mechanism of the stability of Mn+1ACn and to the design of new Mn+1ACn phases. First-principles calculations show that the formation enthalpy of both MC and Mn+1ACn is directly correlated with the charge transfer from M-3d to C-2s and 2p orbitals. Correspondingly, the early transition metals with high electron donation ability are able to form stable MC phases. Among the various MC phases, MC is found to be electron-deficient, which is thus favorable to react with electron-abundant MA to form Mn+1ACn. Therefore, M2AlC and M2SiC can be more readily separated into two-dimensional M2C structures, compared to M2PC and M2SC.
Dwell time and escape tunneling in InAs/InP cylindrical quantum wire
Authors: Li Ming  , Chen Jun  , Gong Jian  ,   School of Physics Science and Technology, Inner Mongolia University, Hohhot 010021, China
Published: December 2020

Within the framework of the effective mass and adiabatic approximation, the electron transport through an InAs/InP cylindrical quantum wire is studied by using the transfer matrix method. The coherent and escape tunneling processes are analyzed in detail. Influence of external voltage and structure size on the dwell time and escape time are discussed theoretically. A resonant phenomenon of the dwell time for different electron longitudinal energies is observed. A peak value of dwell time appearing at some positions of the bound state increases as the energy level decreases. When a bias is applied on this system along the growth direction, all the peaks of the dwell time shift towards the lower energy and become higher with increasing bias. Furthermore, it can be seen that the asymmetry of structure affects the dwell time obviously. Different results are obtained with the increase of asymmetry of the structure, which can be attributed to a competition between the transmission probabilities through the whole structure and that through a single barrier. Besides, the coherent and escape tunneling processes are also investigated by using a finite-difference method between two asymmetrically coupled quantum disks. It is found that the coherent electron remains oscillating in the two coupled disks. When the right barrier thickness of the nanowire is decreased, a roughly exponential decay of the oscillation charge trapped in both quantum disks is observed. The oscillating period is not affected by the right barrier thickness. However, a great influence of the middle barrier on the oscillation period can be found easily.
Thermochromic properties of W-doped VO2/ZnO nanocomposite films with flower structures
Authors: Zhu Hui-Qun  , Li Yi  , Ye Wei-Jie  , Li Chun-Bo  ,   School of Applied Physics and Material, Wuyi University, Jiangmen 529020, China;,   College of Optical-Electrical and Computer Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China
Published: December 2020

Based on the nanocomposite structure and doping modification, we have studied the preparation technology of high performance nanocomposite thin film and its characterization methods. The W-doped VO2/ZnO nanocomposite thin films are prepared successfully on SiO2 substrates by the three-step method. The structure and morphology of the W-doped VO2/ZnO/SiO2 films are analyzed by X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscope. Results show that the films are mainly composed of VO2 and high valence cation W6+ replacing the V ion in the W-doped VO2/ZnO/SiO2 films. It is found that the flake nanocrystallines resemble a flower in shape, and its size and orientational growth are reduced. The thermochromic properties of W-doped VO2/ZnO films are measured and compared with the single-layer W-doped VO2 films on SiO2 substrates with the same thickness. The variation of infrared transmittance of the W-doped VO2/ZnO/SiO2 nanocomposite film is increased nearly two times, the phase transition temperature reduced approximately to 39 °C, and the width of the thermal hysteresis loop is about 6 °C. The W-doped VO2/ZnO/SiO2 nanocomposite film has a high infrared modulation ability, a lower phase transition temperature, and a narrower thermal hysteresis loop. Thus the potential application of this nanocomposite film is significantly improved.
Anomalous diffusion in the formation of Turing pattern for the chlorine-iodine-malonic-acid system with a local concentration depended diffusivity
Authors: Hu Wen-Yong  , Shao Yuan-Zhi  ,   School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275, China
Published: December 2020

We have addressed numerically and analytically the diffusion mechanism of Turing pattern formation for the chlorine-iodine-malonic-acid system with a local concentration depended diffusivity (LCDD) in a two-dimensional space as well as its reciprocal counterpart. It is found that the Turing pattern develops in a normal way of Fickian diffusion when LCDD is not involved, namely with a zero LCDD adjusting parameter. The formation of a Turing pattern evolves in an abnormal way of either subdiffusion or superdiffusion when a non-zero LCDD adjusting parameter is taken into account, and a negative or a positive value of LCDD parameter corresponds to a subdiffusion or a superdiffusion. The sensitivity of the steady amplitude of the activator concentration of a Turing system to a random initial condition increases with increasing LCDD parameter.
Analysis of information entropy of DC-DC converter
Authors: Li Xian-Rui  , Zhu Yan-Li  ,   Institute of Electronic CAD, Xidian University, Xi'an 710071, China;,   Key Laboratory of High-speed Circuit Design and EMC, Ministry of Education, Xidian University, Xi'an 710071, China
Published: December 2020

In order to identify the DC-DC converter system behavior with different feedback coefficient k, we propose a method, which adopts the ideas of limit and the information about entropy to estimate the DC-DC converter nonlinear behavior by considering the characteristics that the stability of the system in a state of cycle and when the system is in chaos will not be repeated. This method analyses the entropy of the system in periodic and chaotic states and can quantify the period-doubling and chaos behaviors in DC-DC converters. In this paper, we simulate the first-order voltage feedback DCM Boost converter and DCM Buck converter. Results indicate that, according to the proposed information entropy, the bifurcation point, cycle number, and the location of the chaos can be accurately reflected. The above method improves the theory and method of the converter nonlinear dynamics analysis.
Theoretical and simulation study of 0.14 THz fundamental mode multi-beam folded waveguide traveling wave tube
Authors: Yan Sheng-Mei  , Su Wei  , Wang Ya-Jun  , Xu Ao  , Chen Zhang  , Jin Da-Zhi  , Xiang Wei  ,   Institute of Electronic Engineering, China Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

To improve the current and output power of the THz traveling wave tube (TWT), a fundamental mode multi-beam folded waveguide (FMMBFW) TWT scheme is proposed. Firstly, an equivalent circuit model FMMBFW for calculating the high-frequency characteristic is established and compared with numerical simulation. Secondly, the transmission characteristic of 60 periods FMMBFW is analyzed. Finally, the beam-wave interaction characteristic of 0.14 THz FMMBFW TWT is completed by numerical simulation and theoretical calculation. When the DC current is 12 mA and the applied voltage is 15.75 kV, the 3 dB bandwidth of 0.14 THz FMMBFW TWT is 25 GHz (128-153 GHz), the maximum gain is 33.61 dB and the maximum output power is 23 W. When the DC current is 30 mA and the voltage is 15.75 kV, the maximum gain is 38 dB and the maximum pulse output power is 63.1 W at 0.14 THz. Compared with the fundamental single-beam folded waveguide (FW) TWT under the same working condition, the 3 dB bandwidth is doubled, its output power is raised by a factor of 9.66 and the interaction efficiency is increased by 3.22 times. Based on the same gain, the length of FMMBFW TWT is just 52.6 mm while the length of single beam FW-TWT is 78.2 mm. The proposed method can increase effectively the current of FMMBFW TWT; and the interaction gain, efficiency, 3 dB bandwidth, output power can be improved. When the gain is the same, a shorted and compact FMMBFW TWT can be constucuted.
Design of the static var compensator adaptive sliding mode controller considering model uncertainty and time-delay
Authors: Wang Xi  , Wang Yu-Hong  , Li Xing-Yuan  , Miao Miao  ,   School of Electrical Engineering and Information, Sichuan University, Chengdu 610065, China
Published: December 2020

Using supplementary controller of static var compensator (SVC) is an effective way for enhancing the transient stability of an interconnected power system. In conventional controller design, SVC is usually considered as a first-order inertial model with known parameters. In this paper, a nonlinear controller design method based on adaptive sliding mode control is proposed to design a SVC supplementary controller. The imprecise of the model and the external disturbances such as time-delay are taking into consideration in the SVC model, and the interconnected system with SVC is considered by the center of inertia model. Then the SVC supplementary controller is designed based on the adaptive sliding control theory to improve the transient stability of the power system. Finally, the effectiveness of the proposed controller is verified using two simple systems. Simulation results show that the designed SVC sliding mode controller is robust to the variation of operation conditions and time-delays, and it has a better performance in enhancing the system stability as compared with the conventional SVC controller.
Hole quantization and conductivity effective mass of the inversion layer in (001) strained p-channel metal-oxid-semiconductor
Authors: Liu Wei-Feng  , Song Jian-Jun  ,   Key Lab of Wide Band-Gap Semiconductor Materials and Devices, School of Microelectronics, Xidian University, Xi'an 710071, China
Published: December 2020

Within the framework of k p perturbation theory, models of the hole quantization and conductivity effective mass for the inversion layer in uniaxially tensile/compressive and Si-based baixially strained p-channel metal-oxid-semiconductor (PMOS) have been established. Results show that: 1) uniaxially compressive technique should be chosen for the carrier mobility enhancement in uniaxially strained PMOS; 2) the magnitude of uniaxial stress will be less than that of the biaxial case to improve PMOS performance using strained technique; 3) strained Si1-xGex is preferred to use instead of using strained Si, when we choose the biaxially strained materials for the PMOS channel. Our results can provide valuable references to Si-based and other strained device and materials design.
Influences of mesoscale sandstorm on the quantum satellite communication channel and performance simulation
Authors: Nie Min  , Shang Peng-Gang  , Yang Guang  , Zhang Mei-Ling  , Pei Chang-Xing  ,   School of Communication and Information Engineering, Xi'an University of Posts and Telecommunications, Xi'an 710121, China;,   School of Electronics and Information, Northwestern Polytechnical University, Xi'an 710072, China;,   State Key Laboratory of Integrated Service Networks, Xi'an University of Electrinic Science and Technology, Xi'an 710071, China
Published: December 2020

Mesoscale sandstorm is a common form of dust weather in Nevada in the US, the northern part in China, and the Middle East countries in the Asia. To investigate the influence of mesoscale sandstorm on the quantum satellite communication channels, the physical characteristics of the dust storms are analyzed first. According to the diffusion model of mesoscale storms, the relationship between the proposed scale dust features and the degree of quantum entanglement is established then. The effect of dust on properties of the quantum satellite channel is simulated finally. The results show that if the diffusion time for the dust is 12 hours, the dust particle radii are 1 and 25 μm, the entanglement degrees of quantum satellite channels are 0.6 and 0.4, the utilization rates of quantum satellite channels are 0.9 and 0.8, the capacities of quantum satellite channels are 0.95 and 0.8. The characteristic parameters of the quantum channels are closely related to sandstorms. Therefore, in order to improve the reliability of quantum satellite communications, the parameters of quantum satellite channels should be adjusted adaptively.
Thermodynamical properties of a three-dimensional free electron gas confined in a one-dimensional harmonical potential
Authors: Shao Zong-Qian  , Chen Jin-Wang  , Li Yu-Qi  , Pan Xiao-Yin  ,   Physics Department, Ningbo University, Ningbo 315211, China
Published: December 2020

We study the thermodynamical properties of a noninteracting electron gas confined in one dimension by a harmonic-oscillator potential. The exact analytical expression for the thermodynamical potential is obtained by using a formula of contour integration. The magnetizations, magnetic susceptibilities, and the specific heats are then studied each as a function of the strength of the magnetic field in different regimes of the temperature and effective thickness. It is shown at low temperature, the magnetization, magnetic susceptibility, and the specific heat oscillate as the strength of the magnetic field increases. Especially, there exist two modes of oscillations for the specific heat in certain regimes of low temperature and effective thickness.
Generation and application of non-ergodic noise
Authors: Liu Yan  , Bao Jing-Dong  ,   Department of Physics, Beijing Normal University, Beijing 100875, China
Published: December 2020

When using the noise of n-order time derivative as an internal thermal noise to drive a generalized Langevin equation, if the nonergodicty strength of the noise satisfies b ≠ 0 and the system is in thermal equilibrium, then the stationary velocity variable of the system can be used as a non-ergodic noise. The spectra of the non-ergodic noise is infinite at zero frequency. The one-dimensional semi-unbounded coupled harmonic oscillator chains connected with the gas molecules act as the non-ergodic noise, which is an example of non-ergodic noise. Finally regarding the non-ergodic noise as an external noise to drive the particles in the titled periodic potential, it is found that there appears superballistic diffusion with the effective diffusion index exceeding a ballistic value of 2. It is also found that the velocity distribution of the system displays two motion states, the “locked state” and the “running state”. And in the “running state” there occurs a bimodal phenomenon, which is a relatively new phenomenon.