Dispersion analysis of reflection grism-pair applied to dispersion compensation
Image reconstruction algorithm for steady-state diffuse optical tomography with structural priori information
Influence of digital averaging on the signal-to-noise improvement ratio of temperature control system used in single-photon detector at infrared wavelength
According to performance requirement of high precision temperature control system used in single-photon detector, the signal-to-noise improvement ratio (SNIR) achieved by digital averaging used in it is analyzed, and the functional relation between SNIR and average times, sampling period, length of sampling time and bandwidth of band limited white noise is given. Aiming at practical application, on condition that the total sampling time is limited, the influences of average time and sampling period on the SNIR of the system are calculated respectively, the expression of SNIR is given and the optimal sampling time is defined.
Preparation of graghene oxide/chitosan composite films and investigations on their nonlinear optical limiting effect
Study of quartz temperature characteristics for precise oscillator applications
Effect of pro-proximity pulse voltage on the third-generation low light level image intensifiers halo effect
Theoretical and experimental investigation of air breakdown on single high power microwave based on the mixed-atmosphere propagation model
Decoherence of a photon-subtraction-addition coherent state in a thermal environment
We investigate the nonclassicality and decoherence of a photon-subtraction-addition coherent state (a++a)m|a> in a thermal environment. Its nonclassicality is discussed by deriving analytically Mandel's Q parameter, photon number distribution, and Wigner function. It is shown that if the condition |2z*+α -α*|2 <1 is satisfied, the Wigner function always presents the negativity for the one-order photon-subtraction-addition coherent state (m=1). Based on the evolution formula of Wigner function, we derive a compact expression for Wigner function in the thermal environment. It is found that when κt<(1/2)ln[(2N+2)/(2N+1)] there is no negativity for the case of m=1. In addition, the evolution of nonclassicality is discussed in terms of the negative volume of Wigner function.
Fractal analysis of spontaneous imbibition mechanism in fractured-porous dual media reservoir
Effect of mixed solvents on P3HT:PCBM based solar cell
Experimental study of the interactions between a pulsating bubble and sand particles with different diameters
The interactions between a spark generated bubble and sand particles with different diameters are studied in this paper using a high speed camera. And distance between the bubble and sand particle is varied. The experimental results show that there are two distinct phenomena during the interaction between the bubble and sand particle. On the one hand, the jet formed is much like that near a rigid wall; on the other hand, a mushroom-shape bubble will form, which will split into two bubbles and two jets with opposite directions along the axes will be generated afterwards. Thus, it is found that the sand particle has the characteristics of a rigid wall and an elastic material. In addition, as the distance d between the bubble and sand particle increases, the pulsating period of the bubble will rise to a peak before it reduces. For different sand particles, the distance corresponding to the peak decreases as the diameter of sand particle increases.
On glass forming ability and thermal stability of Zr57Cu20Al10Ni8Ti5 bulk metallic glass by substituting each component with 1 at% Ag
Study on the mechanical properties of carbon nanocones using molecular dynamics simulation
Structure transformation and magnetisms in Ho2Ni7-xFex compounds
Based on the composite compounds Ho2Ni7-xFex (x=0-3.0), a method of describing the structure transition from rhombohedral to hexagonal is discussed in terms of free electron concentration. The transition is investigated by X-ray powder diffraction and magnetic analysis. The compounds crystallize into the rhombohedral Gd2Co7-type structure for x=0-0.5 and into the hexagonal Ce2Ni7-type structure for x=0.5-2.5. The values of lattice parameters a and c of the Ho2Ni7-xFex compounds increase with the addition of Fe, and the saturation magnetization Ms decreases with Fe content increasing at a rate of d Ms/d x=-2, manifesting antiparallel alignments of the Fe and Ho moment. The higher the free electron concentration, the stabler the rhombohedral structure is, otherwise the hexagonal structure is stabler, which provides a meaningful parameter to distinguish the two allotropies in composite structure intermetallics.
Interactions between ions with different values of Ep/q and alumina capillaries
Study of ion guiding effect of capillaries in insulator is of significance for developing passive-type ionic optics. Interactions between ions with different values of Ep/q, such as 150 keV O3+, 0.32 MeV O+ and 2 MeV O2+, and alumina capillaries are investigated. For projectile ions of 150 keV O3+, a guiding effect exists during the passage of the projectile ions through the capillaries. As the capillaries are tilted with respect to the projectile ion beam, the projectile ions can still pass through the capillaries considerably and the charge state remains unchanged; the spectrum of angular distribution of the ions out of the capillaries shifts by an angle the same as the tilt angle of the capillaries; the penetrating rates of the projectile ions for different tilt angles of the capillaries can be fitted to Gaussion function. For 0.32 MeV O+ and 2 MeV O2+ ions impinging on alumina capillaries, no guiding effect occurs in the interaction process. The maximum value of Ep/q of the projectile ions for guiding effect to occur is less than 320 kV.
Photoluminescence of macroporous α-alumina prepared by polyacrylamide gel technique
Macroporous α-Al2O3 is synthesized by polyacrylamide gel technique. X-ray diffractor combined with a photoluminescence spectrophotometer is used to investigate the formation of Al2O3 phase and the light emission properties of xerogel sintered at different temperatures. It is demonstrated that high-purity α-Al2O3 can be obtained at a sintering temperature of 1150 ℃. Scanning electron microscopy images reveal that the synthesized α-Al2O3 has a monolithic structure. Photoluminescence spectra show that a major emission band around 365 nm and a weaker side band around 330 nm are observed when the excitation wavelength is 228 nm. The pore-formation and luminescence mechanisms of porous alumina are discussed based on the experimental results.
First-principles calculations of microstructure and thermodynamic properties of the intermetallic compound in Ag-Mg-Zn alloy under high pressure and high temperature
The structural stability, elastic and thermodynamic properties of the intermetallic compounds MgAg, Mg4Zn8 and Ag8Mg4Zn4 in Ag-Mg-Zn alloy under high pressure and high temperature are investigated by employing the first-principles method based on the density functional theory. The theoretical results are generally in good agreement with experimental results and similar to the theoretical calculations. The calculated results indicate that the intermetallic compounds AgMg, Mg4Zn8 and Ag8Mg4Zn4 are elastically stable at zero temperature and pressure. Mg4Zn8 and Ag8Mg4Zn4 are of the ductility phase, and AgMg is of the brittleness phase. The plasticity of Ag8Mg4Zn4 is the best in the three intermetallic compounds, and AgMg is the worst. Based on the quasi-harmonic Debye model the vibrational internal energy, vibrational Helmholtz free energy, vibrational entropy, heat capacity of constant volume, heat capacity at constant pressure, thermal expansion coefficient Grüneisen parameter and Debye temperature of the intermetallic compounds in Ag-Mg-Zn alloy under high pressure and high temperature are all discussed.
Performance of steel reinforced high strength concrete investigated in the gas gun experiment
A novel interconnect-optimal power model considering self-heating effect
Influence of modulation structure on the superhardness effect in c-VC/h-TiB2 nanomultilayer
Atomistic characterization of a modeled binary ordered alloy solid-liquid interface
First-principles study on anatase TiO2 photocatalyst codoped with nitrogen and cobalt
The microstructures and optical properties of N and Co-codoped anatase TiO2 are investigated by using the plane-wave ultrasoft pesudopotential method of first-principles. The calculated results show that the octahedral dipole moment of anatase TiO2 increases after N and Co codoping, which is favorable for effective separation of photogenerated electron-hole pairs. Some new impurity energy levels of codoped TiO2 appear between the conduction band and the valence band, which results in the red shift of the absorption wavelength toward visible-light region and an apparent increase in performance of light absorption. These impurity energy levels can promote the effective separation of photogenerated electron-hole pairs, which facilitates the improvement of the photocatalytic efficiency of codoped TiO2. The band edge redox potential of codoped TiO2 is only slightly changed compared with that of pure TiO2, which means that the strong redox capacity of codoping photocatalyst is still excellent.
Theory study of rare earth (Ce, Pr) doped GaN in electronic structrue and optical property
Using the pseudopotential plane-wave method within the density functional theory as implemented in the Vienna ab-initio simulation package, we investigate the crystal parameters, electronic structures and optical properties of rare earth Ce and Pr doped GaN. The local spin density approximation with Hubbard-U corrections method is used to treat the correlation effect of strongly localized rare-earth 4f electron states. The results show that the crystal parameters increase after doping Ce and Pr in GaN. The Ce impurity introduces defect level in the gap while for Pr the level lies near the valence band maximum, and the defect levels are contributed by Ce and Pr 4f electron states. In addition, the dopings of Ce and Pr give rise to spin polarization and magnetic-order. For GaN:Ce, there appear two new peaks, one is in the low energy region of imaginary dielectric function and the other is in the low energy region of absorption coefficient. These new peaks are probably related to the defect level in the gap. For GaN:Pr, red shifts of the dielectric peak and absorption edge duo to bandgap narrowing are observed.
Mageto-transport properties of serial double quantum dots in the spin blockade regime
With the two-impurity Anderson model Hamiltonian, we theoretically study the magneto-transport properties of the serially coupled double quantum dot system in a spin blockade regime, and solve Hamiltonian by the master equation approach. We find that the spin flip tunneling between dots due to the spin-orbit coupling can lift the quantum dot spin blocking. We also study the effects of the spin flip of quantum dots due to the hyperfine interactions and the spin exchange interaction on magnetic transport properties of the system. Some valuable results are obtained and the relevant problems are discussed.
VO2 low temperature deposition and terahertz transmission modulation
0.7 structure of conductance quantization in quantum point contact
Modulation of the band structure of layered BN film with stain
Phase drift of magnetoelectric effect in Terfenol-D/PZT composite materials
Prediction of the magneto-resistivity of manganese oxides La0.67Ca0.33MnO3 and Pr0.7Sr0.3MnO3 via temperature and magnetic field
Bond energy and coordination number model for relaxor ferroelectrics
Field emission properties of silicon doped AlGaN thin film
Investigation on three-photon-absorption fitting method and three-photon-absorption-induced optical stabilication effect of a fluorene derivative
UV Raman and XPS studies of hydrogenous diamond-like carbon films prepared by PECVD
The hydrogenous diamond-like carbon (DLC) films deposited on Si substrates using pulsed glow discharge method are investigated using Raman spectroscopy and X-ray photoelectron spectroscopy method. The UV Raman spectrum for excitation wavelength is 325 nm. UV Raman is particularly useful for hydrogenous DLC, as it gives clear measurements in the D and G peak spectral region even for highly hydrogenated samples, for which the visible Raman spectra are overshadowed by photoluminescence. The sp3 bonding of hydrogenous DLC film can be effectively studied by X-ray photoelectron spectroscopy method, and the data from the X-ray photoelectron spectroscopy method are compared with Raman results. It is found that G peak shows a shift to ward a higher wave under UV excitation. For the G peak, I(D)/I(G), G-FWHM and sp3, there exists a relationship among them.
Room temperature deposition of highly conductive and transparent H and W co-doped ZnO film
The luminescence properties of the Dy3+-doped borosilicate glasses
Improvement of light extraction efficiency of GaN-based blue light-emitting diode by disorder photonic crystal
Ultraviolet photoresponse of ZnO thin-film transistor fabricated at room temperature
Numerical simulation of coupled thermo-mechanical process of friction stir welding in quasi-steady-state
Shock-induced transformation behavior in NiTi shape memory alloy
Preparation of vanadium oxide thin films by oxidation with rapid thermal processing
Experimental study of the settling and melting characteristics of equiaxed crystals in a falling tube
Lipid exhange between membranes: effects of temperature and ionic strength
Chaotic synchronization in complex networks with delay nodes by non-delay and delay couplings
Approximate method of solving solitary-like wave for a class of nonlinear equation
Progress of coupled superconducting qubits
Implementation of the scheme of a quantum information signature based on weak nonlinearity
Complexity analysis of chaotic pseudo-random sequences based on spectral entropy algorithm
Relaxation bursting and the mechanism of four-dimensional Chua's circuit with multiple interfaces
Numerical study on the dynamic behavior of internal structure of 1+1-dimensional ballistic deposition model
Dynamical mechanism of ramp compensation for switching converter
Effects of the aging and systole of heart on the dynamics of spiral wave
A cellular automata model of pedestrian evacuation in rooms with squared rhombus cells
Control of few node genetic regulatory networks
Consistency of a complex delayed dynamical network with stochastic disturbance
Experimental study on frequency stabilization method of internal-mirror He-Ne laser
Frequency of an internal-mirror He-Ne laser is stabilized by using a micro cooling fan, instead of traditional heating method. Both the relationship between driving voltage and rotating speed and the thermal expansion of the intermal-mirror laser are discussed. The cavity length of the laser is controlled and adjusted by air cooling. The frequency stabilization is based on a theory of power balance between two longitudinal modes. The average temperature of the laser tube is less than 50 ℃ when the frequency is stabilized. A frequency fluctuation of less than 1.4 MHz in 20 h and a frequency relative standard uncertainty of U=4.7×10-9 in 4 months are evaluated by measuring the beat signal with a high-precision laser stabilized by iodine.
Measurement of industrial gas pollutant emissions using differential optical absorption spectroscopy
Self-consistent thermodynamical treatment to strange quark matter with density-dependent bag constant and properties of hybrid stars
Relation analysis between cathode ablation and voltage for a magnetically insulated transmission line oscillator
Coherent excitation and control of Rydberg lithium atoms in a chirped microwave field
The time-dependent multilevel approach (TDMA) and the B-spline expansion technique are used to study the properties of Rydberg lithium atom. The energy level structures of high excited states n = 70–75, l = 0–5 and population transfer of lithium atom in a microwave field are studied by numerical calculation. The results show that the coherent control of the population transfer in microwave field from the initial to the target states can be accomplished by optimizing the microwave field parameters. and that each state plays a crucial role in the transition process.
Ab-initio calculations of the crystal-field parameters and energy level structure for Yb3+ doped in tantalate
In this paper, the DV-Xα method of ab-initio calculations and the effective Hamiltonian model are introduced to calculate the crystal-field and spin-orbit parameters of rare earth ions doped in various crystals, especially for the crystal with low-symmetry. For the low-symmetry crystal, the number of parameters is more than that of energy levels, thus experimental energy levels fitting cannot determine all parameters, while ab-initio calculations can determine all crystal-field and spin-orbit parameters accurately. Firstly, the crystal-field and spin-orbit parameters of Yb3+ doped in GdTaO4 crystal are calculated by this model, and then the energy level structure of Yb3+:GdTaO4 is given and the continuous emission band of Yb3+:GdTaO4 emission spectrum is analyzed, which is conducive to the laser tunable and laser mode-locking output, so Yb3+:GdTaO4 is a potential laser medium for high efficiency laser operation and new ultrashort pulse output. Also, the crystal-field and spin-orbit parameters of Yb3+ doped in YTaO4 and ScTaO4 are calculated by this model, and the energy level structures of Yb3+:YTaO4 and Yb3+ :ScTaO4 are given, which leads to a conclusion similar to that drawn from the Yb3+:GdTaO4 crystal.
Theoretical study on He-N2 interaction potential
SnS molecular structure and properties under external electric field
A study on spectroscopic parameters of X2∑+, A2Π and B2∑+ low-lying electronic states of SiN radical
The potential energy curves (PECs) of X2∑+, A2Π and B2∑+ low-lying electronic states of SiN radical are investigated using the highly accurate valence internally contracted multireference configuration interaction (MRCI) approach combining the full valence complete active space self-consistent field method. In the present calculations, the basis sets used are correlation-consistent basis sets, aug-cc-pV6Z. The PECs determined by the MRCI calculations are corrected for size-extensivity errors by means of the Davidson modification (MRCI +Q). To obtain more reliable results, effects of the core-valence correlation and relativistic correction on the PECs are taken into account. The core-valence correlation correction is carried out with the cc-pCV5Z basis set The way to consider the relativistic correction is to use the second-order Douglas-Kroll Hamiltonian approximation, and the correction is performed at the level of cc-pV5Z basis set. With these PECs, the spectroscopic parameters are determined. A comparison with the experimental data shows that the present spectroscopic parameters are more accurate than the previous calculations.
Observation of the avoided crossing of Cs Rydberg Stark states
Accurate calculation of elastic scattering properties of ultracold sodium atoms
Quantum phase transition of a Bose-Einstein condensate in an optical cavity driven by a laser field
Simulation and experiment demonstration of a polarization-independent dual-directional absorption metamaterial absorber
In this paper, we design and fabricat a polarization-independent dual-directional metamaterial absorber. The simulation results indicate that the absorber keeps good absorbing performance in a wide incidence angles for both transverse electric and transverse magnetic polarization, and that the high absorption is due to the dielectric loss of substrates. The experimental results indicate that the absorber achieves dual-directional high absorption at normal incidence, and that the peak absorptions are 95.9% and 90.8%, respectively. The metamaterial absorber is very thin, and its thickness is approximately 1/34 of the working wavelength. The metamaterial absorber has many advantages such as high absorption, small thickness, simple design and easy processing.
Theoretical study on the electron energy distribution function of weakly ionized air plasma
The electron energy distribution function (EEDF) of weakly ionized air plasma (79% nitrogen and 21% oxygen) is investigated by solving the Boltzmann equation with the spherical harmonics expansion. It is found that the EEDF deceases sharply in an energy range from 2 to 3 eV for low reduced field (E/N < 100 Td), and the high energy tail of the EEDF decreases more sharply than Maxwell distribution. When the reduced field increases to a range 400 to 2000 Td, the EEDF approaches to Maxwell distribution. When the reduced field is greater than 2000 Td, the high energy tail (>200 eV) of the EEDF deceases more slowly than Maxwell distribution. It is shown that the EEDF approaches to Maxwell distribution in a high frequency field. The effective electron temperature is dependent only on E/ω for ω >> vm, but on E/N for ω << vm. The electron-electron collisions play no significant role until the ionization degree is bigger than 0.1%. This is different from the case of monatomic plasmas, in which the EEDF is influenced by electron-electron collisions for ionization degree greater than 10-6.
Effect of cylinder-electrode on magnetoelectric heating of ions
Experimental study of L-H transition triggered by supersonic molecular beam injection in the HL-2A tokamak
Radiation model and experimental research on novel pinhole-assisted point-projection backlight
Monte Carlo model and variance reduction method based on lidar of ship wake
The numerical simulation of ship wake laser scattering mechanism and the detection process are important foundations for the laser detection and guidance of the ship wake. The feasibility that Monte Carlo method is introduced into the numerical simulation of lidar of ship wake is analyzed firstly. The Monte Carlo simulation model of laser detection of ship wake is developed with the actual parameters of self-developed lidar of ship wake. The causes of the large variance and low photon utilization of simulation results are in-depth analyzed by statistics on the simulation results. To resolve this problem, the method of photon collision forced in the receive optical fields, the photon splitting method with the total free pach of photon serving as a criterion, and the conbination of the two methods are put forward based on partial sampling theory and the basic principle of division-roulette bet. The comparative analyses of the simulation and the experimental results show that the proposed model simulation results fit to experimental data better, thus the correctness of the model is verified. The photon collision forced in the receive optical field and division-the roulette method can effectively reduce the variance and increase the photon utilization. In this paper, the Monte Carlo method is introduced into the simulation process of lidar of ship wake.
Numerical comparison between Ta and Nanbu models of Coulomb collisions
Two models (Ta and Nanbu) of Coulomb collisions are compared theoretically, and the difference in scatter angle between Ta model and Nanbu model is analyzed particularly. The model of Coulomb collisions between electrons in the code which is developed already with Ta model is rebuilded with Nanbu model. Then, the codes with Ta model and Nanbu model are used for simulating electron energy distribution in JAEA 10 A respectively. The results of simulation are compared with the experimental results, showing that the electron energy distribution is closer to Maxwell distribution with Coulomb collisions and the Nanbu model is more accurate than the Ta model.
The numerical study of full three-dimensional particle in cell/Monte Carlo with gas ionization
Analysis of imaging an extended X-ray source by using a Fresnel phase zone plate
Influence of SiC intermediate layer on adhesion property of F-DLC film
One-dimensional simulation of radiation transport in three-dimensional cylinder
In indirect driven inertial confinement fusion experiments, one-dimensional radiation hydrodynamics code is used to simulate radiation transport in material confined in a cylinder and large bias is generated due to two- or three-dimensional lateral effects like energy losses into the cylinder wall. Lateral X-ray radiation losses such as cylinder wall loss and direct leak from the detection holes are simulated through analytical view factor equations and albedo power laws. Modifications are made for a one-dimensional radiation hydrodynamics code MULTI which is successfully used in the simulation of measured hydrodynamic trajectory of X-ray-heated gold plasma and better result is obtained than without taking lateral effect into account, which proves that this modification is practical.
Responses of the land-surface process and its parameters over the natural vegetation underlying surface of the middle of Gansu in loess plateau to precipitation fluctuation
Quick search algorithm of X-ray pulsar period based on unevenly spaced timing data