Impact of (Al, Ga, In) and 2N preferred orientation heavy co-doping on conducting property of ZnO
At present, although there is some studies about the theoretical calculation studies of Zn1-xTMxO1-yNy(TM=Al, Ga, In) p-type doped have been reported. But, they are random doping and without considering the asymmetry of ZnO preferred orientation to doping. Therefore, Six different supercell models Zn1-xTMxO1-yNy (TM = Al, Ga, In. x = 0.0625, y = 0.125) which proportion is TM:N = 1:2 and preferred orientation to co-doped have been constructed based on the first-principles plane wave ultra-soft pseudo potential method of density function theory, in this study.Then calculate the geometric optimization, State density distribution and Band structure distribution for all models, respectively. Results indicate that with the condition of heavily doped and preferred orientation to co-doped, in the same kind of preferred orientation co-doping systems, the electrical conductivity of the system which TM-N bond along the c-axis direction is greater than it perpendicular to the c-axis. In the different kinds co-doping ZnO systems which TM-N bond along the c-axis direction, The co-doping systems of In-N bond along the c-axis direction has the strongest conductivity and the lowest ionization energy and the largest Bohr radius. It is more favorable for electrical conductivity of p-type ZnO. This study can be a theoretical guidance for improve the electrical conductivity of which design and preparation TM:N=1:2 ratio preferred orientation co-doping ZnO systems.
Theoretical study of the effect of W-doping on the conductivity of β-Ga2O3
First-principle study on the effect of high Pr doping on the optical band gap and absorption spectra of TiO2
Thermoelectric properties of chalcopyrite Cu3Ga5Te9 with Sb non-isoelectronic substitution for Cu and Te
Effect of temperature and external magnetic field on the structure of electronic state of the Si-uniformlly-doped GaAs quantum well
Breakdown voltage analysis for the new Al0.25 Ga0.75N/GaN HEMTs with the step AlGaN layers
Nuclear magnetic resonance experimental study on the characteristics of pore-size distribution in muck under several typical loading cases
Effect of magnetic capacitance in the Fe3O4 nanopartides and polydimethylsiloxane composite material
Photoluminescence of monocrystalline silicon irradiated by femtosecond pulsed laser
Influences of gold/silver nanoparticles on fluorescence of europium-doped films
Terahertz absorption of graphene enhanced by one-dimensional photonic crystal
Study of mini-themionic electron sources for vacuum electron THz devices
Study on wide-band scattering from rectangular cross-section above rough land surface with exponential type distribution using FDTD
Research on the fabrication and property of hydrophobic antireflective infrared window
An unusual pulse compression of stimulated Brillouin scattering in water
Pulse compression is an important property of stimulated Brillouin scattering (SBS), and the SBS pulse duration becomes smaller with the increase of pump energy. An unusual pulse compression was investigated of the stimulated Brillouin scattering in water, it was found that the SBS pulse duration becomes larger as the pump energy increases. The pulse duration of SBS alters differently with the change of pump energy in strong focusing and weak focusing. Numerical simulation of pump light transmission in water cell has been made to explain the unusual pulse compression phenomena. Different real gain lengths in strong and weak focusing make different SBS pulse compression.
Reduction of the angular dispersion in self-diffraction signals by using a prism
Generation of 266 nm continuous-wave with elliptical Gaussian beams
High power red to mid-infrared laser source from intracavity sum frequency optical parametric oscillator pumped by femtosecond fiber laser
Introduction of two-dimensional defects in inverse opal films by means of planar lithography and sol-gel co-assembly methods
Phase singularities of an ultrasonic speckle field back-scattered from an underwater Gaussian interface
Research on prediction and methods of evaluating sound exposure from a mixture of multiple single sources
In this paper, the prediction and the way for calculating the total exposure level (to be denoted by LTotal) from a mixture of multiple single sources are proposed, on the premise that each single exposure level from every component single source (to be denoted by Li, where i denotes the number of single sources and i=1, 2, …, K) is known. Firstly, a novel method for sound exposure level evaluation, based on a short-term exposure level in the duration of the sound event, is proposed. Using this method, each single exposure level obtained from all the single sound samples and the total exposure level obtained from every artificially combined sound samples are evaluated. Then, we lay special stress on analyzing the quantitative relationships between LTotal and Li (i=1, 2, …, K) measured in three types of sound exposure indicators. All analytical results indicate that our anticipative gain of the total exposure level LTotal from a mixture of multiple single sources can be predicted on the premise that each single exposure level from every componential single source is known. To modify the predicted results, we just need to know the number of specific independent components K and the range of the single exposure levels ρ.
Design of multistatic sonar space-time code detection signal and time reversal copy-correlation detection technology
Passive source localization using RROA based on eigenvalue decomposition algorithm in WSNs
Research and design of thermal concentrator with arbitrary shape based on transformation thermodynamics
Lattice Boltzmann simulation of slip flow and drag reduction characteristics of hydrophobic surfaces
Vortex structures in turbulent channel flow modulated by a steadily distributed spanwise Lorentz force
Theoretical and experimental investigations on aero-optical effect at the second stage of the compressible mixing layer
Using dimensional analysis and experimental technique, the aero-optical effect at the second stage of a compressible mixing layer has been investigated. The theoretical analysis focuses on the relation between two-dimensional large-scale structure of a mixing layer and its corresponding aero-optical effects. Results show that the time-averaged bore-sight error (BSE) has nonlinear variability with the convective Mach number (Mc). Moreover, we also present the relation among time-averaged BSE and turbulent kinetic energy, Reynolds shear stress at the interface between the mixing layer and free stream. Experimental results from a thin beam light passing through the compressible mixing layer verifly the theoretical result between time-averaged BSE and Mc.
Evaluation of vortex criteria by virtue of the quadruple decomposition of velocity gradient tensor
Vortices play a crucial role in fluid dynamics, which is closely related to fluid diffusion mixing, force, heat, and noise. Five widely-used vortex identification criteria, i.e. the ω-criterion, Q-criterion, Δ-criterion, λci-criterion, and λ2-criterion are analyzed, and four of them are compared with each other based on the velocity-gradient-tensor decomposition method. A new quadruple decomposition method (QDM) is introduced for the first time, so far as we know, to decompose fluid motions into four fundamental components: dilatation, axial deformation along the principal axes of the strain-range sensor, planar motion, and pure shearing. This method helps make the kinematic implications of the four vortex identification criteria more clear. It is found that the mean rotation of fluid elements always contains the pure shearing motion. Non-zero mean rotation ω does not guarantee the existence of the spiraling streamlines, e.g. in a typically parallel shear flow. A positive Q value indicates the strength of the pure rotation of a fluid element in the 2D complex eigenvalue plane on top of the axial deformation, which however is a sufficient but not a necessary condition for the existence of pure rotation. The Δ-criterion can correctly tell the existence of pure rotation, but cannot accurately determine its strength. The λci-value represents the absolute strength of the pure rotation, which is the combined effect of the canonical rotation in the complex eigenvector plane and the pure shearing. The proposed QDM enables us to achieve a deeper understanding of vortices and motions in fluid dynamics.
Study on a rising bubble bouncing near a rigid boundary
Study of far-field pressure wavelet of air-gun bubble based on potential flow theory
Dynamic characteristics of laser-induced bubble moving in venturi
Drag reduction on micro-structured hydrophobic surfaces due to surface tension effect
Influence of defects on friction and motion of carbon nanotube
Research on dark signal degradation in 60Co γ-ray-irradiated CMOS active pixel sensor
Improved properties of boron-doped zinc oxide films with In2O3：Sn interlayers for solar cells
Boron-doped zinc oxide (BZO) films with a natural pyramid-textured surface grown by metal organic chemical vapor deposition (MOCVD) have large light trapping effect in thin film silicon solar cells when used as front contact electrodes. However, the surface topography of traditional BZO films is so sharp as to damage the quality of the subsequent silicon thin film materials and to reduce the photovoltaic conversion efficiency of the solar cells. In this work, an ultra-thin In2O3:Sn(ITO)film (～ 4 nm) is used as the interlayer in the sandwiched structure of the multilayer films, i.e. glass/bottom BZO layer /ITO interlayer/top BZO layer. The surface properties can be improved through modulating the thickness of the top BZO layer. Appropriate thickness of top BZO layer and ITO interlayer are helpful for obtaining the cauliflower-like surface morphology and thus the sharp structure becomes relatively gentle, but the surface morphology still keeps a pyramid feature when depositing thicker top BZO layer. The relatively gentle surface morphology could promote crystallization quality of μc-Si:H thin film materials and reduce cracks in intrinsic layer and TCO/P-Si interface defects. Finally, this new sandwiched structure of multilayer ZnO films is applied in μc-Si:H p-i-n thin film solar cells. Compared with traditional BZO films, the quantum efficiency (QE) of solar cells with a sandwiched structure of ZnO increases by about 10%, and both the open-circuit voltage (Voc) and short-circuit current density (Jsc) may increase and thus improve the solar cell efficiency.
Switching dynamic behavior of a ferroelectric bilayer film
Correlation between fracture mechanism and fracture toughness in metallic glasses
Single-channel source separation of radar fuze mixed signal using advanced adaptive decomposition
Design and evaluation of a pre-traveling wave deflector magnetic solenoid lens focused streak image tube
Reduction of metal artifacts caused by multiple metallic objects in computed tomography
High-attenuation objects like metals will result in metal artifacts in computed tomography images. Compared with single metallic object, artifacts due to multiple and large-scaled metallic objects is more complicated in representation and have much worse effects on reconstructed image. State-of-the-art metal artifacts reduction for multiple metal objects based on interpolation method cannot solve the beam hardening inside the metals, and can easily make mistakes in segmentation and interpolation. Aiming at reduction of multiple metallic objects, this paper simulates the production of the artifacts and proposes a metal artifacts reduction method based on projections correction. In this method, metal regions are firstly segmented directly from projection domain, and then a correction model is established for projections in metal regions. Finally, correction is made by adjusting parameters of the model. The optimal solution of the parameters is achieved by NM-simplex method that makes the gray entropy of the reconstructed image minimum. The simulation results and obtained data show that the present method significantly improves metal artifact due to multiple metallic objects and provides a better image quality than that obtained using interpolation.
Research and application of multi-chamber heart magnetic field model
A multi-chamber heart magnetic field model with two atria and two ventricles, boundaries of which were picked up from a magnetic resonance imaging, was established based on the boundary element method (BEM). Moreover, the model-based 36-channel cardiac magnetic field data and magnetic field maps at a specific time were analyzed. We also studied the heart electrical activity during ST-T segment from patients with complete right bundle branch block (CRBBB) and complete left bundle branch block (CLBBB) by the model, respectively. Results show that the model-based magnetic field map generated by the electrical excitation with a moving single current dipole in single bundle branch is similar to the magnetocardiogram (MCG) of the CRBBB/CLBBB patient acquired using a superconducting quantum interference device (SQUID) in cardiac repolarization. It demonstrates that the multi-chamber heart BEM model can be used to study cardiac magnetic inverse problem of CLBBB/CRBBB patient. In addition, two evaluation criteria are given as follows: the ratio of the maximum on the magnetic field strength measurement plane in the multi-chamber model to that in the single-chamber model; and the ratio of root mean squares of the magnetic field strength at the 36 measurement points of the two models. This result indicates that the magnetic field maps generated by the multi-chamber heart model are close to the measured MCG maps. In this model, the strength and topography of the magnetic field lie in the conductivity parameters of cardiac tissues, the position and the number of the equivalent current dipoles.
Review of reconstruction algorithms with incomplete projection data of computed tomography
Conformal symmetry and Mei conserved quantity for ageneralized Hamilton system
Particles discrete element method based on manifold cover for macro-mesoscopic fracture of rock mass
Analysis and calculation of a 170 GHz megawatt-level coaxial gyrotron
Trust, evolution, and consensus of opinions in a social group
Blind source separation of chaotic signals in wireless sensor networks
Effect of coupling modes and initial structures on the synchronization of a ring network with fractional order bistable oscillators
A ring network with fractional-order bistable oscillators is proposed, and the relationship between synchronization and parameters, such as coupling modes and the initial structural conditions, etc., is investigated. Based on the bistable characteristics of P-R oscillator, the effects of the coupling strength and the structures in initial conditions on the dynamic behaviors of the ring network are investigated by analyzing the largest conditional Lyapunov exponents, the largest Lyapunov exponents and the bifurcation diagrams, etc. Further investigation reveals that the ring network can be controlled to form chaotic synchronization, chaotic non-synchronization, synchronous amplitude death, synchronous non-amplitude death, etc. by changing the initial conditions and the coupling strength. Furthermore, the contours of the largest conditional Lyapunov exponents and the largest Lyapunov exponents also show how the dynamic behaviors of the network are influenced by the competition between couplings along directions of y and z, strongly relies on the initial structural conditions of network.
Chaotic control of the interconnected power system based on the relay characteristic function
A least square support vector machine prediction algorithm for chaotic time series based on the iterative error correction
Automatic detection of epileptic EEG based on recurrence quantification analysis and SVM
An authenticated key agreement protocol based on extended chaotic maps
Effect of defect on the programming speed of charge trapping memories
The programming speed of charge trapping memories (CTM) with different defects were studied based on the first principle and VASP package. The defects include threefold oxygen vacancy (VO3), fourfold oxygen vacancy (VO4), hafnium vacancy (VHf), and interstitial oxygen (IO). Trapping energy, energy band offset, and the trapping density were calculated and compared. Results show that VO3, VO4 only trap holes, VHf only trap electrons, and IO trap electrons and holes; the most important is the trapping energy which is greater in VHf. It is the best for trapping charges; because the charge tunneling into trapping layer is easy in VHf. It can also reduce the tunneling time. Finally, the trapping densities were compared with each other: VHf's trapping density is greater than other defects, i.e. charges can be trapped easier than by other defects. All of these show that VHf is the best one for reducing programming time. This paper will provide a theoretical guidance for increasing the programming speed of CTM.
First principles calculation of dielectric properties of Al and N codoped 3C-SiC
Band inversion in half Heusler-type Na1-xCsxAlGe(0 ≤ x ≤ 1)
The influences of doping whit congeners on the band topology in half Heusler-type of NaAlGe alloys are investigated using the first-principles calculations. It is found that the Na1-xCsxAlGe alloys with a normal band order are converted into topological nontrivial phases when x is up to 0.125. We argue that it is the degree of hybridization between Al and Ge determine the band order at the Fermi level. The Na or Cs only plays a role of the valence electron contributor and influences the lattice parameter.
Accuracy study for excited atoms (ions)：A new variational method
For the computation of excited states, the traditional solutions of the Schröedinger equation, using higher roots of a secular equation in a finite N-dimensional function space, by the Hylleraas-Undheim and MacDonald (HUM) theorem, we found that it has several restrictions which render it of lower quality, relative to the lowest root if the latter is good enough. In order to avoid the variational restrictions, based on HUM, we propose a new variational function and prove that the trial wave function has a local minimum in the eigenstates, which allows to approach eigenstates unlimitedly by variation. In this paper, under the configuration interaction (CI), we write a set of calculation programs by using generalized laguerre type orbitals (GLTO) to get the approximate wave function of different states, which is base on the HUM or the new variational function. By using the above program we get the approximate wave function for 1S (e), 1P (o) state of helium atoms (He) through the different theorems, the energy value and radial expectation value of related states. By comparing with the best results in the literature, the theoretical calculations show the HUM's defects and the new variational function's superiority, and we further give the direction of improving the accuracy of excited states.
Slow ions 84Kr15+, 17+ bombardment on GaAs
We have investigated surface morphology and visible light emission from slow ions Kr15+, 17+ colliding with GaAs (100). The surface disorder of GaAs films mainly depends on the charge state of incident ions. The two spectral lines of target atom Ga belong to transitions of GaⅠ 4p 2P1/2o–5s 2S1/2 at 403.2 nm and 4p 2P3/2o–5s 2S1/2 at 417.0 nm. Light emissions of target species depend on the energy of the incident ions deposited on the target surface atoms. During the neutralization process, the four spectral lines of Kr+ respectively can be attributed to the transitions of Kr Ⅱ 4d 4F7/2–5p 2D5/2o at 410.0 nm, 5s 2P3/2–5p 4S3/2o at 430.4 nm, 5p 4D3/2o–4d 2D3/2 at 434.0 nm and Kr Ⅱ 4d 4D1/2–5p 2S1/2o at 486.0 nm. They are induced by cascade de-excitation after many electrons of the conductions band of the solid surface captured in highly excited states of the incident ion. Intensities of these six spectral lines from incident ions Kr17+ are obviously larger than Kr15+'s.
Optimization of the light-induced-fluorescence signals of single atoms and efficient loading of single atoms into a magneto-optical trap
In our experiment, firstly, we carry out the loading of single atoms in the magneto-optical trap (MOT) by increasing the quadrupole magnetic field gradient, improving the background vacuum, and reducing the diameters of the cooling and trapping laser beams. Secondly, we get the single atomic fluorescence signal of a high signal-to-background ratio in the MOT by means of reducing the detuning of cooling light and increasing its intensity appropriately, and using the polarization spectroscopy locking technique to suppress the fluctuations of cooling laser. In addition, with the real-time feedback on quadrupole magnetic field gradient, we demonstrate a probability of loading single atoms in the MOT as high as 98%. We also measure the statistical properties of the single atomic fluorescence which is excited by continuous light in the MOT; the measured second-order correlation is g(2)(τ = 0) = 0.09.
Experimental study of insulated aluminum planar wire array Z pinches
The distribution of large-scale drought/flood of summer in China under different configurations of monsoon and polar vortex