The stochastic averaging method for a quasi-integrable Hamiltonian system has been applied to the study of the motion of active Brownian particles. Firstly, the stochastic averaging method is introduced. Then, the stationary solution of the dynamic equations governing an active Brownian particle moving in a plane with Schienbein-Gruler velocity-dependent friction model subject to Guassian white no...
Using the Lie symmetry under infinitesimal transformations in which the time in not variable,a new conserved quantity of holonomic mechanical systems in terms of quasi-coordinates is studied.The differential equations of motion of the systems are established.Determining equations of Lie symmetry under infinitesimal transformations are given.The Hojman theorem is generalized.Finally,an example is g...
Nonlinear mechanics of thin elastic rod, as a model of DNA, aroused extensive interest as a joint research subject of mechanics and molecular biology. The study of the equilibrium of a thin elastic rod constrained on a surface found an important application in industry, especially in molecular biology. In the present paper the constraint equations and constraint forces of the elastic rod are analy...
In this paper, the form invariance of second-order linear nonholonomic systems in the phase space is studied. The definition and criterion of the form invariance of secondorder linear nonholonomic systems in the phase space is given. The structure equations and the conserved quantities of the form invariance are obtained. and an example is given to illustrate the application of the results.
Non-uniform microchannels are used in the micro space propulsions and micro gas turbine generators. The performances of these applications are determined primarily by the performance of the microchannel used. Based on the micro-fabrication technology, three-dimensional rectangular cross-section straight-convergent-divergent-straight (SCDS) microchannel was fabricated. Its width in the throat cross...
We have simplified the extended Jacobi elliptic function expansion method, namely, improved the modified Jacobi elliptic function expansion method. We applied this method to solve the coupled nonlinear Schr?dinger equation of Manakov type and obtained some Jacobi elliptic envelope solutions and corresponding solitary wave solution, shock wave solution.
Group theory is introduced into the calculation of photonic band gap with the plane wave expansion method, and improved calculation formulae are derived. Both the analysis and the practical band gap calculation for an exemplary twodimensional case have shown that, as compared with the conventional plane wave method, the group theory based improved algorithm can substantially release memoryspace ...
Divergence structure for the quantum entropy of a black hole in Anti-de Sitter spacetime due to the electromagnetic and gravitational fields is investigated by using the brick-wall model. The entropy has both linearly and logarithmically divergent terms, where the linearly divergent term can reduce to the form proportional to the event horizon area if the temperature is replaced by the Hawking te...
An approach of the harmonic signals extraction from chaotic interference is proposed. Based on empirical mode decomposition and the concept that any signals are composed of a series of the simple intrinsic modes, and the chaoic interference signals are decomposed to a series of intrinsic mode functions, the harmonic signals can be extracted. Simulation results show the approach is satisfactory.
A general framework algorithm is proposed for energy minimization control for a discrete chaotic system. A quadratic performance function is first given and the chaotic system is decomposed into a linear and a nonlinear parts. Then, the twolevel algorithm is presented to solve the nonlinear optimal control problem: The first level predicates the nonlinear part of the chaos system; the second leve...
In order to find some relation between phase synchronization and dynamical topological variation in chaotic systems with many rotational centers,we propose a method of linear amplitude coupling to study the phase synchronization of Lorenz system and Duffing system.First,we convert the original Lorenz system and Duffing system into the dynamics of amplitude and phase.Based on linear amplitude coupl...
By constructing an odd function with multiple piecewise-linear segments in the double-folded torus chaotic attractor equation and using recurrence algorithm, the recurrence formula capable of producing a family of multi-folded torus chaotic attractors is derived. Utilizing the recurrence formula thus derived and selecting properly the slope values of piecewise-linear segments, the values for equil...
The statistical performance of detecting optically rough surfaces with pulsed laser radar using energy detection techniques has been investigated in this paper. Under the far field condition, the analytical expressions for computing the speckle number integrated by the receiving aperture is presented, and the speckle number subtended by the telescope is found to be dependent only on the relative s...
We have discussed the Dirac method and Faddeev-Jackiw method in the quantization of constrained systems. The equivalence of motion equation and canonical quantization in the two methods has been proved, and also the correspondence relation of constraints found.
Based on the canonical Ward-Takahashi identities to include composite fields to study gauge symmetry dynamical breaking for Abelian gauge theory in higher-order derivative systems, the mass spectra of both fermion and bound states are obtained. The effect of higher-order derivative terms on mass generation is discussed.
The degree of isospin fractionation is measured by the ratio of saturated neutron-proton:i.e. the ratio of gas phase (nucleon emission) to that of liquid phase (fragment emission) in heavy ion collisions. We have studied the dependence of the degree of isospin fractionation on the neutron-proton ratio in the colliding system by using isospin-dependent quantum molecular dynamical model. The calcula...
We have designed a series of trans-stilbene derivatives with different arrangement of the substituents and studied their one-photon and two-photon absorption properties by using the response theory methods at HF level. The calculations show that these molecules have strong two-photon absorption cross sections. In the visible light region, the maximum two-photon absorption cross section for molecul...
The first and second kind formulas of angular dispersion, corresponding respectively to the polar angle and azimuthal angle of diffraction grating, are presented based on the generalized grating equation produced on the basis of vector diffraction theory under the condition of conical diffraction mounting; at the same time, by making theoretical and numerical analysis of the condition in which th...
In this paper, the quantum properties of light in a system of two coupling atoms interacting with a single-model squeezed vacuum field at the two-photon transition in Kerr medium are studied by means of quantum theory.The influences of the Kerr medium and the dipole-dipole interaction between atoms are discussed. The results show that when the Kerr effect and the dipole-dipole interaction between ...
In this paper, the interactions between a two-level atom and a coherent field with a time-varying frequency have been studied. The two typical cases, in which the frequency of the field varies with time in the form of sine or impulse, have been considered. It is found that the collapse and revival phenomena of the atomic population inversion will disappear as the frequency changing with time in si...
The generalized M2 factor of rotationally symmetric truncated beams is studied in detail by using the asymptotic analysis, generalized truncated second-order moments method and self-convergent beam width approach. The physical relation between the three methods and how to determine the generalized M2 factor in a unified way are analyzed and illustrated with numerical results.
A novel coupled large optical cavity cascaded by tunnel-junction semiconductor lasers is put forward to resolve the major difficulties of ordinary laser diodes. In this structure several active regions are cascaded by tunnel junctions to couple a large optical cavity. This structure can solve the problem of catastrophic optical damage of facet and large vertical divergence caused by thin emittin...
Based on the linear dependence of laser pulse energy on the ablation area, the ablation threshold fluence of sapphire is calculated in this paper. Meanwhile the threshold fluence of sapphire as a function of pulse duration is studied with an ultra-short pulse laser. The experimental results agree well with the theory of avalanche mode. Finally we discussed the photon absorption mechanism of the co...
The design uses a composite Yb:YAG/YAG disc laser configuration with the pump light incident from the disc edge. The crucial advantages of the thin-disc design is that the thermal gradients are aligned with the beam propagation direction, the transverse temperature gradients are reduced, previous difficulties with high average power pumping/cooling and the rejection of amplified spontaneous emiss...
Tunable wavelength converters are key components in intelligent all-optical network. In this paper, a novel scheme for tunable wavelength conversion based on semiconductor-fiber ring laser is proposed. Probe laser in the conventional scheme could be left out and self-started tunable wavelength conversion could be achieved. Theoretical model for this novel scheme is also established and the output ...
Based on the quasi-steady stimulated Brillouin scattering theory, the nonlinear propagation of 1.064μm, YAG nanosecond pulsed light was analyzed numerically and treated with a theoretical model that includes the spontaneous nature of the initiation of stimulated Brillouin scattering(SBS). Then the pulse propagation and power limiting effects (including both power limiting and energy limiting) were...
The nonlinear hot image effect from phase scatterer in a high-power laser system has been investigated theoretically and numerically. According to the Fresnel-Kirchhoff diffraction integral and nonlinear paraxial wave equation, we derive the functional relationship of the intensity of hot image and its location. It is shown that the image intensity is likely several times larger than that from amp...
Using the one dimensional particle in cell simulation code, we have studied the generation and redshift of harmonics from overcritical plasma layer irradiated by ultrashort intense laser pulses. Except for the strong oscillations of target surface driven by the laser field, the light pressure of the intense laser can ablate and push the target suface, which is the reason for the redshift of harmon...
In this paper the spatial chirp and the angular dispersion for femtosecond optical parametric oscillation(OPO) are calculated theoretically and analysed. The analytical expression of the spatial chirp in the nonlinear crystal(BBO) is presented. And the analytical expressions of second-and third-order dispersions including angular dispersion of the nonlinear crystal for the noncollinearly phase-mat...
Considering the atomic coherences and injected classical field, we derived the n-Onphase-locking Lorenz-Haken equation by using the technique of stochastic differential equations. The effects of detuning, injected field and the atomic coherence on the dynamical characteristics of this equation is then numerically studied. The results show that in laser working situations, the detuning can result i...
By coupling two doped one-dimensional photonic crystals, a novel photonic crystal film heterostructure with both functions of frequency and spatial filters is proposed. In a broad frequency range, this optical film filter only transmits light of a selective frequency at normal direction and reflects light of this selective frequency at all other directions; while all other frequencies within the b...
The transmission properties of the one-dimensional photonic crystals with defects were studied using the eigen matrix method, and a new kind of tunable optical filter is proposed in this paper. When the one-dimensional photonic crystals (L1H1)m have defects such as LcH2(L2H2)n, there will be a narrow transmission band in the gap of the photonic crystals, meanwhile the other transmission peak will...
It was shown theoretically and experimentally that a metamaterial composed of periodically positioned split ring resonators (SRR) can lead to a negative effective permeability μeff close to its resonance frequency. In this paper, the nearest neighbor interactions between hexagon SRR were investigated in experiment. The experimental results show that there is only one resonance frequency for a one-...
We introduce a technique, chirped pulse cross-correlation, for single shot THz detection. The time-resolution limitation of previously demonstrated single-shot amplitude modulation spectral encoding is analyzed. The new technique is free from the limitation.
In this paper we report the measurements of the damage threshold and ablation depth for fused silica by laser pulses at the wavelength of 800 nm, with the pulse duration ranging from 45 to 800fs. These results can be well understood by using an improved avalanche model. The model includes the production of conduction band electrons(CBE), laser energy deposition, and CBE diffusion. The evolution of...
A novel method for multiplexing fiber-optic Fizeau strain sensors based on optical amplification is proposed and demonstrated for the first time to our knowledge. This method overcomes the two intrinsic disadvantages of fiber-optic Fabry-Perot strain sensors, i.e. weak signal and difficult multiplexing. Also, the amplified spontaneous emission and optical amplification of the Erbiumdoped fiber pu...
The sweep down flow and related flow structures in a turbulent boundary layer were visualized with hydrogen bubble method. The streamwise and transverse vortices induced by sweep down flow near the wall of a vessel were observed. A new kind of vortical structure, whose features are contrary to those of the hairpin vortex, was observed in the present experiments. It is termed “contrahairpin vortex...
PHYSICS OF GASES, PLASMAS, AND ELECTRIC DISCHARGES
An auxiliary differential equation finite-difference time-domain (ADE-FDTD) methodology for anisotropic magnetized plasmas is derived. The method is based on a difference approximation of the auxiliary differential equation. A comparison with the JEC method is included. The CPU time saving by several times and accuracy of the method are confirmed by computing the reflection and transmission throug...
The whole ablation process of target heated by pulsed lasers is studied in this paper. Under the appropriate dynamic boundary conditions, have been investigated in detail the heat flow equation with heat generation term, and the temperature distribution of target before and after the melting. In particular, after target melting, the temperature distribution and the interface position between the s...
In the form of joint experiment between China and Russia, the experimental studies of Zpinches of mixed wire array of aluminum (A1) and tungsten (W) were carried out on S-300 generator,which was located on Kurchatov Institute of Russia. The experimental results were compared with those of single A1 array and single W array, respectively. There are obvious difference between mixed one and single o...
Considering the Coulomb explosion induced by the interaction of a deuterium cluster target with an ultra-intensie femtosecond laser, the mechanism which generates energetic deuterium nuclei for the fusion has been analyzed.The formulas for expansions of deuterium ion clusters, which are driven by Coulomb explosion, are proposed; and hence the kinetic energies of deuterium nuclei and the expansion ...
By using Y-Ni-C composite rod as cathode, large amount of single-walled carbon nanotubes was produced by an improved arc discharge method, in which a tungsten rod was used as an electrode and the electrodes were exchanged after each discharge. The raw soot was characterized by high resdution electron microscope and Raman spectrum, and the results show that this is an efficient way to produce large...
CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES
Individual high-aspectratio carbon nanofibers(CNFs) were grown on W wire by plasma-enhanced hot filament chemical vapor deposition method, using a gas mixture of methane and hydrogen. The average diameter and length of carbon nanofibers are 60—100 nm and 6—30 μm, respectively, and the density of carbon nanofibers is less than 10.6cm-2. The field emission properties from individual carbon nanofiber...
In this paper the magnetic field profiles produced by coil currents of I=115.2A,I=137.7A and I=137.7A with a SmCo permanent magnet under the substrate holder in the deposition chamber and plasma chamber in the single-coil divergent field MWECR(micro-wave electron cyclotron resonance) CVD system was investigated. Then the magnetic field gradient of these magnetic field profiles was obtained quantit...
The laser-micro-Raman spectra of near-stoichiometric LiNbO3 crystals were measured and analyzed. The crystals were grown by flux pulling method. Compared with the congruent LiNbO3 crystal, the number and frequency of Raman spectral lines of A1(TO) and E(TO) modes have no change. It was validated that the LiNbO3 crystal is substitutional solid solution. The relative intensity of 738cm-1 Raman peak(...
Using the renormalization-group transformation and cumulant expansion technique, the Gaussian model with two-spin interactions and triplet-spin interactions on the Sierpinski gasket lattice is studied, and its fixed points and critical exponents are obtained. Compared with the case of only two-spin interactions, the fixed points and critical exponents have changed. The results show that the fixed ...
A strategy based on wavelet transform to describe surface morphology of thin films is presented in this paper.The evolution of surface morphology of Cu-W thin films with deposition time on silicon wafers was investigated by discrete wavelet transform (DWT) method. The results show that the surface morphology of the thin films is unstable until the sputtering time exceeds 10 min. The surface morp...
Diamond thin films were prepared by using chemical vapor deposition. It is enhanced to etch the sp2 bonding carbon atoms of the film by intermittently closing the methane gas during the deposition. These films were characterized by Raman spectroscopy and microscopy. The results show that the enhanced etching of sp2 bonding carbon atoms has no obvious effect on quality and microstructure of the dia...
CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES
In C60 molecules, the lowest unoccupied molecular orbital has T1u symmetry. The orbital is easily occupied by an electron through molecular inner excitation or doping and becomes an active Jahn-Teller (JT) electronic state. The T1u-hg- JT system is formed by the coupling of such an electronic state to a five-fold degenerate hg mode. The linear vibronic coupling in the system forms a trough on the ...
The structure and transport properties of perovskite (La1-xYx)2/3Ca1/3 MnO3 (0≤x≤0.3) systems are systematically investigated. It is found that all the compounds show a single phase structure. With the increase of Y3+ doping content the metalinsulator transition temperature TMI(M—I) shifts to lower temperatures. While the relevant resistance peak ρp is sharply increased, for the sample of x=0.3, ...
Lattice vibration of one-dimensional copolymer chains was studied and the dispersion relation was obtained numerically. The character of the vibration modes was recognized. It was found that the interface modes may appear if the homopolymer blocks have a strong interaction with each other, whose frequencies lie in the band gap between the acoustic and optical branches or between two optical branch...
We investigate the high-resolution thermoelectric power of Bechgaard salt (TMTSF)2ClO4 in temperatures between 6 and 280K for metallic state with different cooling rates through the anion-ordering transition Ta=24K. There is a linear temperature-dependent thermoelectric power at high temperatures, which cannot be explained by conventional one-dimensional(1D) electron band theory. A sudden change o...
The scheme of attosecond high-order harmonic generation driven by a two-pulse laser field is proposed. Calculated results show that, not only a single attosecond x-ray pulse can be produced with two pulses, which may break the energy limitation of the few-cycle pulse, but also the intensity is even higher than that generated by a single laser pulse with the same intensity.
The two-dimensional electron-gas (2DEG) distribution, sheet density and subband occupations in AlxGa1-xN/GaN heterostructure are calculated by solving the coupled Schrdinger and Poisson equations selfconsistently. By involving degree of relaxation to distinguish the spontaneous and piezoelectric polarizations, the influence of the polarizations and the doping in the AlGaN barrier on the 2DEG pro...
Multicomponent excited-state emissions from monomer, exciplex and electroplex were observed in a bilayer organic electroluminescent device with a structure of ITO/TPD(60nm)/PBD(60nm)/Al(where TPD and PBD stand for N,N′diphenylN,N′bis(3-methylphenyl)1,1′biphenyl4,4′diamine) and (2(4′biphenyl)5(4″tertbutylphenyl)1,3,4oxadiazole, respectively). The difference between the photoluminescence of this de...
A theoretical study, within the effective-mass approximation, on the coupling effects of applied magnetic fields along the growth direction of the superlattice on the surface electron states in a semi-infinite semiconductor superlattice is presented by using an effective-barrier height method. The coupling effect is necessarily considered when the difference of the electron effective masses betwee...
We study theoretically the properties of the ground state of a mescopic ring with a seriescoupled double quantum dot in the Kondo regime by means of the two-inpurity Anderson Hamiltonian. The Hamiltonian is solved by means of the slave-boson mean-field theory. It is shown that two dots can be coupled coherently, which is reflected in the appearance of parity effects and the complex current-phase ...
The perovskitetype manganites Ca(Mn2Cu1)Mn4O12 were prepared using the conventional solid state reaction method. X-ray diffraction patterns show that the annealing in air at 1073 K after the first sintering at higher temperatures can reduce the volumetric percentage of impurity phases in samples. Magnetic measurements indicate that the samples exhibit ferromagnetic antiferromagnetic transitions a...
The perovskite La0.67Pb0.33MnO3 with a Curie temperature TC=360K has been characterized by measuring the zero-field-cooled(ZFC) and field-cooled(FC) moments over a wide range of temperature 2K
Fe-R-O (R=Hf, Nd and Dy) films were made by reactive sputtering technique and annealed at 400℃. X-ray diffraction and electron diffraction show that nanometer scale Fe grains are embedded in amorphous Roxide matrix. Inplaneferromagnetic resonance was systematically carried out to measure the inplaneresonance absorption spectra and utilized to analyze the relationship between the local magnetizatio...
The dielectric, piezoelectric, ferroelectric and pyroelectric properties of (Bi0.5Na0.5)1-xBaxTiO3 (x=0.00,0.04,0.06,0.08, 0.12) ceramics prepared by sol-gel method were investigated. It was found that all the samples in this experiment show improved piezoelectric properties,obtained by using this chemical method. For(Bi0.5Na0.5)0.94Ba0.06TiO3 ceramic, as its composition is near the morphotropic p...
Ferroelectric SrxBa1-xNb2O6 (0.2<x<0.8, SBN100 x= thin films of highly preferred c axis orientation have been grown on Si (100) substrate by the sol-gel method with post annealing at 1000°C. Investigated by x-ray diffraction and second ion mass spectrum,we observed that the SBN thin films prepared using NbCl5 precursor solution contained K+ ions, compared with Nb(OC2H5)5 precursored SBN films. By ...
In this paper we present a solution that addresses the reflectance loss due to oxidation. The solution is a capping layer (CL) that acts as an effective oxidation barrier when the multilayer (ML) is exposed to the extreme ultraviolet (EUV) light in the presence of water vapor, so that the optical element of multilayer can be used as long as possible. The theoretical reflectivity of ML Mo/Si EUV mi...
INTERDISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY
The crystal structures, surface morphology and ferroelectric properties of Bi3.25La0.75Ti3O12 (BLT) thin films were found to be greatly affected by the baking temperature during sol-gel processing. At lower baking temperatures, the (117) orientation in the BLT thin film was preferred. However, with the increase of baking temperature, the (117) diffraction peak became weaker. In addition, the surfa...
Influence of pressure on solidification microstructure of FeSi2 alloy is investigated. Different from the eutectic structure of the sample solidified at normal pressure, the microstructure of the sample solidified at high pressure is composed of dendritic primary phase and anomalous eutectic. The significant change in microstructure results from the change of phase diagram and solute atom diffusio...
In this article, synthesis of nanographite powders using pure TNT ( trinitrotoluene )explosives is reported. X-ray Diffraction (XRD) results indicated that the detonation product has a hexagonal-graphite structure and the average size of the particles of graphite is 1.86—2.61nm. Specific surface area of nano-graphite is about 500—650m2/g measured by BET gas sorption instrument.Crystal grain size ...
In light of irreversibility of atmospheric motion, the memory function obtained by utilizing the previous information fully obtained from the observational data is introduced. The selfmemorization equation of the heat conduction equation is induced, and the stability and characteristics of which are studied, taking respectively Richardson scheme (RS) and DuFort-Frankel scheme (DS) as the retrospe...
Dirac equation near horizons of Vaidya-Bonner-de Sitter black hole is discussed. Its Hawking temperature and radiation spectrum are calculated accurately. At the same time, the equation of event horizon is given, which is consistent with the result calculated by zero-curve equation.
The entropies of quantum fields on event horizon of a toroidal black hole are given using the improved brick-wall model. According to the view of the improved brick-wall model, these entropies are nothing but the entropy of the black hole. So the entropy of the toroidal black hole is proportional to the area of event horizon, which satisfies the Bekenstein-Hawking formula.