Tunneling mode in symmetrical one-dimensional photonic crystal of single-negative material
The beam propagation factor and the kurtosis parameter of a Gaussian vortex beam
Analysis of the facula of partially coherent vortex beam in propagation
The propagation law of the cross spectrum density is employed to derive the analytical expression of the elements of the cross spectrum density matrix in the observation plane for partially coherent vortex beam after propagation under the condition of paraxial approximation. Based on the derived result, the intensity distribution in the observation plane is analyzed. It is shown that different from the completely coherent vortex beam, the partially coherent votex beam has an intensity of the center-point in the observation plane, which gradually becomes prominent after propagation, and the intensity distribution in the observation plane tends to the distribution of Gaussian-like type with the increase of propagation length. The evolution of intensity distribution depends on the topological charge and correlation length of the source beam. On the condition that other parameters of the source beam are invariable, the beam will evolve fast if the topological charge is small and the correlation length is short. Finally, for the first-order partially coherent vortex beam, the detail of the evolution of the beam shape is investigated by studying the extremum of the intensity in the observation plane. And the theoretical proof is presented for the rule of the evolution of the beam.
Propagation of helical beams through amplitude diffractive optical elements and the measurement of topological charge
Diffraction efficiency measurement of large aperture multilayer dielectric grating and its application in the fabrication process
Experimental study of 8-bits information transmission system based on orbital angular momentum of light beams
Ionization currents and terahertz emission from the interaction of few-cycle laser pulses with gas targets
Off-focus generation of strong super-continuum emission in fused silica using high power femtosecond laser pulses
Spatially induced Airy-Bessel light bullets
Measurements of transient reflectance spectra of dynamic gratings by optical frequency modulation
A scheme for improving optical signal-to-noise ratio of multi-carrier source based on recirculating frequency shifter
The output quality of frequency-locked multi-carrier source based on recirculating frequency shifter (RFS) technology is easily influenced by the inherent high-order harmonic crosstalk of modulator, especially the third-order crosstalk. In order to reduce the third-order crosstalk, a scheme that another RF signal whose frequency is 3fm is loaded on both ports of I/Q modulator is adopted. The first-order signal it produces is used to suppress the third-order crosstalk. A multi-carrier source whose number is 24 and maximal power difference is smaller than 0.1 dB is achieved through theoretical analysis and simulation research. The effective optical signal-to-noise ratio (OSNR) of multi-carrier source is improved by 2 dB compared with that before using the scheme of suppressing third-order crosstalk.
Investigation of the collapse of laser-induced bubble near a cone boundary
Fabricating three-dimensional periodic micro-structure with planar defects via a single exposure
The method of quantitative characterization using reflection pulsed thermography
In this paper, a new method using reflective pulsed thermography to measure defect depth, thermal wave reflection coefficient and thermal diffusivity is presented. First, a brief description of the pulsed thermography in terms of theoretical background and quantitative measurement is given. One stainless steel 304 structure machined several flat-bottom holes in which it is filled with different materials are used as experimental sample, the measured results of defect depth, thermal diffusivity and reflection coefficients at defect interface under different conditions are given. The agreement between the results obtained by using pulsed thermography and the value presented in the literature or measured by other techniques appears satisfactory within errors of ±5%, and possible reasons for affecting the measurement precision are discussed.
Analytical model for acoustic multi-relaxation spectrum in gas mixtures
To identify the correlation between sound propagation and molecular multimode vibrational relaxation in polyatomic gas mixture, an analytical model that constructs acoustic multi-relaxation spectrum is presented. The frequency-dependent effective specific heat of gas is formulated from the micro view of vibrational mode energy transfer as well as the macro view of relaxation process due to vibrational-vibrational mode energy coupling. With the aid of the general relaxation equations of multimode vibrational energy transfer, the analytical expressions to calculate acoustic relaxation absorption and dispersion, which reflect both primary and secondary relaxation processes, are developed from the effective specific heat. The constructed absorption spectra of various gas mixtures, consisting of carbon dioxide, methane, nitrogen, and oxygen, accord with the experimental data very well. Especially, the peak errors of those results are less than 1%. Moreover, the simulation results illustrate that less than two single processes with higher strength appear generally in a multi-relaxation absorption spectrum. Compared with the existing models, the analytical model can directly obtain the analytical expressions of characteristic points in the relaxation spectrum of gas mixtures, which makes it advantageous to analyze the spectral characteristics qualitatively and quantitatively. Consequently, the model provides an effective approach to analyzing the relationship between sound propagation and molecular vibrational relaxation of gas mixtures.
Application of leading structure on thermal protection of nosetip
Investigation of a energy conversion silicon chip based on 63Ni radio-voltaic effect
Helicities and thermostabilities of Ni nanowires in the carbon nanotubes
Effect of high pressure treatment on microstructure and resistivity of Cu75.15Al24.85 alloy
The microstructures of Cu75.15Al24.85 alloy before and after treatment at 1–5 GPa pressure and 750℃ for 15 min are analyzed by optical metallograph, X-ray diffraction, scanning electron microscopy and differential scanning calorimeter, and its resistivity is also obtained through resistivity measuring instrument. According to the obtained results, the effects of high pressure treatment on the microstructure and resistivity are investigated. The results show that high pressure treatment can refine the microstructure, and increase the resistivity of the alloy. When the pressure is 3 GPa, the refinement is more remarkable and the resistivity reaches a maximal value.
Lattice constant deviation from Vegard's law in GeSn alloys
First-principles study of p-type ZnO by Te-N codoping
The influence of deuteration and helium-implantation on the surface morphology and phase structure of scandium thick film
Research on the total dose effects for domestic VDMOS devices used in satellite
The study on the stress and the friction coefficient of tetrahedral amorphous carbon films bombarded by energetic Ar ion
Helium effect on the stability of the interface of Cu/W nanomultilayer
The electronic theory study on high-temperature oxidation mechanism of TiAl alloy
In order to reveal the physical nature of high temperature oxidation of titanium-aluminous alloy from the electronic level, the atom embedded energy, affinity energy, binding energy and other electronic structure parameters are calculated by using recursive method combining with Castep, and the alloy oxidation mechanism is explored. The results show that there is a larger oxygen solubility in titanium and oxygen atoms can aggregate into titanium matrix near surface, and gradually spread into the deep matrix. Oxygen and titanium have a strong affinity to form a titanium oxide film. Aluminum can form clusters with mutual attraction between aluminum atoms in titanium matrix. Titanium atoms in aluminum clusters are mutually repulsive and form chemical compounds with aluminum atoms. Because of the closing affinity energy between aluminum and titanium with oxygen, the preferential oxidation of aluminum cannot occur, but titanium oxide and aluminum oxide form. The binding energy of Al2O3 is slightly lower than that of TiO2, therefore Al2O3 is more stable. Aluminum in TiO2 has a greater solubility, which can replace titanium to form more stable oxide Al2O3.
Study on the electronic structures and energy band properties of Cd-doped wurtzite BeO
The electronic structures and energy band properties of the Cd-doped wurtzite BeO are investigated by plan-wave pseudopotential method with the generalized gradient approximation in the frame of density functional theory. The theoretical results show that the valence band maximum is determined by O 2p states and the conduction band minimum is occupied by Cd 5s and Be 2s orbitals based on the total density of states and partial density of states of Be1-xCdxO alloy. With the Cd content x of Be1-xCdxO increasing, the repulsion effect between Cd 4d and O 2p states is more enhanced and the bandgap of Be1-xCdxO is reduced. At the same time, the bandgap undergoes the direct-indirect-direct transition. In order to obtain the theoretical values in accord with the experimental results, the bandgaps of Be1-xCdxO are corrected. Moreover, the relations among energy bandgap, bowing parameter and lattice constant of the wurtzite BeO-ZnO-CdO ternary alloy are analyzed.
Transport properties of nonlinear chains with random dimer nonlinearity parameters
First principles study of the elastic, electronic and optical properties of MgS under pressure
Effects of the improved hetero-material-gate approach on sub-micron silicon carbide metal-semiconductor field-effect transistor
The influence of gate voltage on electron transport in the graphene field-effect transistor under strong laser field
Study of stability of persistent spin helix in two-dimensional electron gases with spin-orbit coupling
Study on the self-heating effect in silicon-on-insulator devices with SOANN buried oxide
Reliability of SiN-based MIM capacitors in GaN MMIC
Electromagnetic wave scattering by a topological insulator prolate spheroid particle
Study on SQUID method and Campbell method measure superconductors
Effects of Gd and Co doping on the electrical and ferromagnetism properties of BiFeO3 ceramics
Laser-induced ultrafast spin transfer in linear magnetic molecular ions
Influence of core-shell structure on dielectric behaviour in relaxor ferroelectrics
Spectroscopic and thermal properties of Yb doped CaF2-SrF2 laser crystal
Ultrafast spectroscopy of the Mn3+ d–d transition in YMnO3 film
Photoinduced carrier dynamic behavior of the Mn3+ 3d resonance excitation of YMnO3 thin film is studied by the femtosecond time resolved spectroscopy. The photon energy of the pump pulse is tuned to 1.70 eV, which is corresponding to the Mn3+ 3d energy level at room temperature. With resonant excitation, the transient transmission signals at the zero-delay time gradually increase with temperature increasing. The temperature dependent transmission change results from the blue shift of the Mn3+ 3d energy level, which is believed to originate from the short-range antiferromagnetic order in YMnO3 film. In addition, the fast and slow relaxations of the transient signal arise from electronic-phonon and phonon-spin interactions, respectively. When the temperature is lower than TN, the relaxation time of the fast process increases significantly, which indicates that the strength of electronic-phonon coupling is restrained by the long-range antiferromagnetic order.
Investigation of the cathode electric field at the initial stage of explosive electron emission
Electronic properties of disordered bilayer hexagonal boron nitride quantum films
Based on the Anderson tight-binding model, the electronic properties of disordered bilayer hexagonal boron nitride quantum films are investigated. Our numerical results show that the electrons in a disordered bilayer hexagonal boron nitride quantum film are localized, presenting an insulating property. However, for the monolayer disordered bilayer hexagonal boron nitride quantum film, the energy spectrum has persistent mobility edges which are independent of the disorder strength. This indicates that a metal-insulator transition occurs in the monolayer disorder structure. This is similar to the case in an order-disorder separated quantum film. The results could offer useful information for understanding and manipulating the electronic properties of bilayer hexagonal boron nitride quantum films.
Calculation of beam-wave interaction of coupled-cavity TWT using equivalent circuit model
A nonlinear model for the numerical simulation of coupled-cavity traveling wave tube is described. The model is based on the Curnow equivalent circuit from which the matrix equations for the fields of any single cavity can be obtained. And the model can be divided into the matrix equations, the motion equations and the space-charge field equations, in which the sever, dynamic tapering in the circuit and the multiple-frequency signal amplification can be also considered. The simulation is used to analyze the nonlinear AM-PM distortion and the intermodulation products of a coupled cavity TWT whose working frequencies range from 59 GHz to 64 GHz. And the analysis of the saturated output power within the frequency band is also included. Comparing the simulation results with the measurements, the percentage difference between the calculation results and the test results is less than 5%.
Design and simulation of 140 GHz high power staggered double vane traveling-wave tube
Staggered double vane slow wave structure (SWS) and sheet electron beam are employed to investigate a 140 GHz high power traveling wave tube. Numerical calculation of eigenmode shows that the SWS has a good characteristic of dispersion and interaction impedance. The transition structure, input/output coupler and concentrated attenuator are especially proposed for the circuit to ensure that the tube will work well. Particle-in-cell simulation results demonstrate that the traveling wave tube can provide over 300 W of peak power in a frequency range of 132-152 GHz with a maximum of 546 W and a corresponding gain of 37.37 dB at 138 GHz assuming a beam power to be 5.115 kW and input power to be 0.1 W. The output power of the tube can exceed 440 W in a frequency range of 128-152 GHz with a corresponding interaction efficiency of over 8.6% when the input powers range from 0.027 W to 0.46 W. Such a traveling wave tube has a great significance and a potential application in high power short millimeter wave field.
Highly color-stability flexible white organic light-emitting devices fabricated by color conversion method
Efficiency droop in blue InGaN/GaN light emitting diodes on Si substrate
The investigation of performance improvement of GaN-based dual-wavelength light-emitting diodes with various thickness of quantum barriers
Random walks on spatial networks
In this paper, we construct a cost constrained spatial network by adding long-range connections to the one-dimensional circle. The probability for a long-range connection between nodes i and j is pij∝ dij-α (α≥ 0), where dij is the lattice distance and the total length of the long-range connections is set to be ∧=cN(c≥ 0), where c is a positive constant and N is the network size. According to the simulation and numeric results, we find an optimal power-law exponent α0 such that the mean first-passage time is shortest. Furthermore, the shortest mean first-passage time has the power law relationships with the network size N. With the increase of network size N and the total cost ∧, the optimal power-law exponent α0 increases monotonically and approaches 1.5.
Research on non-linear beam-wave interaction of W-band gyro-TWT with helical waveguide
Experimental investigation of different Bell-type inequality in three-qubit Greenberger-Horne-Zeilinger states
Properties and coherence-controlling of entanglement of a two-qubit Heisenberg XY chain with intrinsic decoherence
By solving the Milburn equation, we investigate the thermal entanglement properties of a two-qubit Heisenberg XY chain in the presence of intrinsic decoherence. The controls of nonuniform magnetic field, the initial state of two qubits, the relative phases and the amplitudes of the polarized qubits on thermal entanglement are studied. The results show that for a particular initial state, the thermal entanglement can be increased by the external magnetic field. The time behavior of the entanglement exhibits a strong dependence on the initial state of two qubits, and it can be manipulated by changing the relative phase and the amplitudes of the polarized qubits. It is also notable that stable entanglement, which is dependent on initial state of the qubit, occurs even in the presence of decoherence. The magnetic field may have a constructive effect on the stable entanglement for a certain initial state, and the Bell-diagonal state turns out to be a "dark" state of the system in the absence of the magnetic field.
Broadcast and multicast in quantum teleportation internet
Fabrication and characterization of single Nb/NbxSi1-x/Nb Josephson junction for voltage standard
The core device of Modern programmable Josephson voltage standard is Josephson junction array. The most advantageous Josephson junction array is Nb/NbxSi1-x/Nb material array. The advantages of Nb/NbxSi1-x/Nb material Josephson junction are that three-layer film production process is simple, Nb and NbxSi1-x etching processes are the same and NbxSi1-x potential barrier layer components can be easily adjusted. In this paper, we investigate the NbxSi1-x/Nb single Josephson junction in National Institute of Metrology. Through measuring the dc current-voltage characteristics under low temperature (4.2 K), superconducting tunneling current and a zero voltage state jumping to voltage state are observed clearly, finally the measurement results are discussed. The work is the first study on Nb/NbxSi1-x/Nb single Josephson junction in China.
Free particle geodesic affine parameter time-space coordinate systems
The resonant behavior of an over-damped linear fractional Langevin equation
Suprathreshold stochastic resonance of a non-linear multilevel threshold neuronal networks system
Brownian motion in a harmonic trap: magnetic tweezers experiment and its simulation
Feature analysis in frequency domain of Duffing system based on general local frequency
Stabilities and bifurcations of sine dynamic equations on time scale
Study on period doubling bifurcation in current-mode SEPIC converter
Bounded damped oscillatory solutions of Fisher equation
A novel method of estimating parameter and its application to blind separation of chaotic signals
Information entropies and dynamics in the stochastic ecosystem of two competing species
Detecting unstable periodic orbits from continuous chaotic dynamical systems by dynamical transformation method
Saturation property of mean growth of initial error for chaos systems
Controllability of complex networks based on propagation immunization
Effect of weighted scheme on synchronizability based on different network structures
Complex spatiotemporal behaviors in a transmission line system terminated by an N-channel metal oxide semiconductor (NMOS) inverter
Based on the traveling wave theory, a nonlinear discrete map of a transmission line system terminated by an N-channel metal oxide semiconductor (NMOS) inverter is established. After simulating by the nonlinear discrete map, it is found that the change of the reflection coefficient may lead to spatiotemporal bifurcation and chaos, and that the initial distribution significantly affects the spatiotemporal pattern of steady state. For the zero initial distribution, the spatiotemporal pattern is very regular, whereas the complex spatiotemporal pattern may appear when the initial distribution is nonzero. The analysis results demonstrate that the complex spatiotemporal behaviors originate from the infinite-dimensional essence of the transmission line and the nonlinear voltage-ampere characteristics of the NMOS inverter.
Complexity-based pattern recognition and diagnosis for engineering simulation system of HTR-PM
Redundancy-test-based hyper-parameters selection approach for support vector machines to predict time series
Precision spectroscopy of helium using a laser-cooled atomic beam
The 23P0,1,2 fine structure interval of 4He can be determined to 10-8 accuracy both theoretically and experimentally. It can be used either to determine the fine structure constant or to test the quantum electrodynamics theory. To reach this goal, it is necessary to measure the fine structure splitting to sub kHz accuracy by increasing the signal-to-noise ratio and eliminating the systematic deviations. In the experimental configuration of present study, transverse laser cooling is used to obtain an intense metastable helium atom beam. The triple state metastable atoms are also bent from the original atomic beam to reduce the background noise. The spectral scanning will be accomplished by tuning the sideband of a frequency-locked diode laser to maintain sufficient frequency stability during the scan. The experimental method has been tested on the setup recently built, and the analysis shows that a sub-kHz precision is feasible.
Study on characteristics and fluid sensing of unparallel wall fiber micro-cavity Mach-Zehnder interferometer fabricated by femtosecond laser micromachining
Observation of transitions in strontium triplet state and its application in optical clock
Mass shift effect on relativistic high-order harmonic generation
The P-branch emission spectral lines in the 2Δ3/2-12Δ3/2 system of VO molecule
STM study of single cobalt atoms and clusters adsorbed on Rh (111) and Pd (111)
Simulation of spectrum of doped Ar in indirectly driven implosion target
The effect of the proton layer initial size on the proton beam characteristic in target normal sheath acceleration
The proton beam accelerated by the interaction of laser with plasma has practical applications in radiography of dense plasma, fast ignition in inertial confinement fusion, and cancer treatment. The application domain is determined by the characteristic of the proton beams, which is affected by a lot parameters. In order to investigate the effect of the initial size of the proton layer, the two-dimensional Particle-In-Cell (2D-PIC) code Flips2D is used. The total energy of proton beam vs. time is studied, and the relation between the duration of acceleration and the period of laser pulse is obtained. The effects of the proton layer initial width and thickness on the divergence angle and the energy spectrum of the proton beam are investigated. The relation between the proton beam characteristics and proton layer initial size is obtained.
The study of meteorological effects and time variations of the fair weather atmospheric electric field near ground in YBJ, Tibet
Magnetization of degenerate and relativistic electron gas