Heat Transfer in Surface Layer of a T15k6 Heterogeneous Hard Alloy under Pulsed High-Energy Irradiation

Russian Physics Journal - A one-dimensional model of a hard alloy is proposed, which takes into account the heterogeneity of the physical properties of a composite material by representing it as a...     

The exact solution for the free induction decay in a quasi-one-dimensional system in a multi-pulse NMR experiment

The exact solution for the free induction decay in a one-dimensional system in the multi-pulse experiment is obtained at both high and low temperatures in the approximation of nearest neighbor interactions. The experimental investigation is performed on a quasi-one-dimensional system of ¹⁹F nuclear spins in a single crystal of fluorapatite. The theoretical results are in a good agreement with the obtained experimental data.     

准一维三平行链无序系统电子结构

利用负本征值理论计算方法,重点计算出准一维平行三链无序系统的电子态密度,对比研究了一维单链、准一维双链的情况.在对角无序、非对角无序条件下,具体探讨了电子结构、局域化形成、系统能量分布及维数效应等问题.研究表明,对角无序主要引起电子局域态的增多,非对角无序则使系统的能量分布范围发生变化;通过对一维到带状系统电子结构变化的研究,观察到在相同条件下,从一维到带状系统,电子态密度的峰值数目在增加,而电子态密度为零的能量区间减少,体现出电子能带结构的维数效应.     

一维双流体分层/段塞流模型的特征根分析

采用特征根方法对描述水平和倾斜管内气液分层流/段塞流的一维双流体模型进行适定性分析.系统分析了气液两相密度、粘性和管道倾角对一维双流体模型适定性的影响。计算结果表明:液相密度、气相粘性和管道下倾角的增大能拓宽方程组求解的适定区域;适定界线与气液两相流流型转变界线之间存在内在联系.     

One-dimensional plasmon in an atomic-scale metal wire

We have measured one-dimensional (1D) plasmons in an atom wire array on the Si(557)-Au surface by inelastic scattering of a highly collimated slow electron beam. The angular dependence of the excitation energy clearly indicates the strong 1D confinement and free propagation of the plasma wave along the wire. The observed plasmon dispersion is explained very well by a quantum-mechanical scheme which takes into account dynamic exchange-correlation effects, interwire interactions, and spin-orbit splitting of the 1D bands. Although the qualitative feature of the plasmon dispersion is reminiscent of that of a high-density free-electron gas, we detected the substantial influence of electron correlation due to strong 1D confinement.     

On Tagged Particle Dynamics in Highly Confined Fluids

Heuristic approaches to the statistics of tagged particle motion in a one-dimensional hard point particle fluid are discussed. An exact expression is obtained for the finite N case with arbitrary single-particle interactionless dynamics. This is extended to the mean over tagged particles as N→∞, and a simple form presented in terms of elementary physical quantities. Extension to single-file flow under quasi-one-dimensional confinement is initiated.     

The self-assembly of gallium oxide microribbons under the action of capillary forces

This paper examined self-assembly in a quasi-one-dimensional mesoscale system. The micro-sized β-Ga₂O₃ ribbons with rectangular cross-section can self-assembled into well-ordered arrays through the evaporation of solvent in the suspension. A mechanism called convective self-assembly, in which immersion lateral capillary forces between the microribbons and the convective flows are regarded as the driving force for the self-assembly, can be used to understand the self-assembly in our experiments. This method can be applied to other non-spherical micro/nanometer particles with high aspect ratio to form ordered and aligned structure.     

Phase Transition in Particle Systems with a Nonnegatively Defined Interaction Potential

We have obtained equations for calculating the parameters of phase transitions in particle systems with a nonnegatively defined interaction potential. The parametrized Gibbs distribution is part of the basis of our derivation. It takes the features of a non-negatively defined interaction potential into account and leads to the corresponding Bogolyubov chain of equations. Using this approach, we obtain a convenient method for finding the free energy of the system. On the basis of this method, we have studied the phase transition in a system of hard spheres and the dependence of the phase-transition temperature on the temperature of argon at high pressures.     

External field induced tricritical phenomenon in the isotropicnematic phase transition of hard non-spherical particle systems

The effect of static external field is studied on the isotropic–nematic phase transition of a system of hard non-spherical particles (rods or platelets) with negative anisotropic polarizability (susceptabilities). On the basis of Onsager theory, the phase coexistence curve is calculated numerically without any approximation. It is found that a weakly ordered nematic phase (uniaxial planar) is in coexistence with a highly ordered biaxial nematic phase which ends at a tricritical point. In the limit of infinite field strength, the orientations of the particles are confined in a plane perpendicular to the field and continuous isotropic–nematic phase transition takes place.     

Accessible solitary wave families of the generalized nonlocal nonlinear Schrödinger equation

Two-dimensional accessible solitary wave families of the generalized nonlocal nonlinear Schr?dinger equation are obtained by utilizing superpositions of various single accessible solitary solutions. Specific values of soliton parameters are selected as initial conditions and the superposition of known single solitary solutions in the highly nonlocal regime are launched into the nonlocal nonlinear medium with a Gaussian response function, to obtain novel numerical solitary solutions of improved stability. Our results reveal that in nonlocal media with the Gaussian response the higher-order spatial accessible solitary families can exist in various forms, such as asymmetric necklace, asymmetric fractional, and symmetric multipolar necklace solitons.     

Resonant frequency shifts induced by a large spherical object in an air-filled acoustic cavity

Acoustic resonances are modified when objects are introduced into a chamber. The magnitude of these changes depends on the object position, size, and shape, as well as on its acoustic properties. Here, an experimental study concerning the resonant frequency shifts induced by a solid spherical object in a quasi-one-dimensional air-filled acoustic cavity is reported. It is shown that Leung's theory does not account quantitatively for the observations. A novel and simple approach is proposed, based on the wave equation in a cavity of variable cross section. The results fit more accurately the measured frequency shifts.     

Dynamical study of the necklace states

Based on finite-difference-time domain methods (FDTD), we have numerically directly investigated the dynamical effects of necklace states on the transmission for one-dimensional (1D) random systems with pulsed incidence in time domain. The necklace state propagation property, which is faster than the common localized modes, is demonstrated directly. From the instantaneous decay coefficient κ(t) and the instantaneous transmittance spectrum T(τ,ω), we have constructed a dynamical picture for the random systems with necklace states. In the picture, we have explained the high plateau on the κ(t) curves by the properties of necklace states, and then defined the time range of high plateau as the “effective time range” of necklace states effects. Further more, we have confirmed the dynamical picture by the ensemble study of random configurations. For the different length, we show that the effects of necklace states will be stronger if the system is longer. Besides these, we also introduce the instantaneous decay coefficient and the instantaneous transmittance spectrum to study the dynamical effects of necklace states. This theoretical study of necklace states can be helpful not only for the deeper physical understanding of necklace states, but also for the experimental observation of necklace states.     

Equilibrium properties of hard non-sphere fluids

Derivation of the thermodynamic properties of fluids of hard non-spherical molecules of arbitrary symmetry is based on the decoupling approximation. Theoretical expressions are given and calculations made for the equation of state and virial coefficients for hard ellipsoids. These results are compared with Monte Carlo values and show fair agreement in all cases. The theoretical predictions for the equation of state for binary mixtures are compared with the Monte Carlo results for hard spheres and hard prolate spherocylinders. Theoretical expressions for the first order quantum correction to the free energy, pressure and virial coefficients are also given. The quantum effects increase with increase of density and with increase of anisotropy parameter.     

Threshold properties of quasi-one-dimensional self-trapping

Excitons in a molecular chain, incorporated into a solid matrix, are considered. Self-trapping phenomena in such a system involve one-dimensional electronic motion and three-dimensional lattice deformation. It is shown that self-trapping in such a quasi-one-dimensional system (contrary to a true one-dimensional system with linear exciton-lattice coupling) is of a complicate threshold character. This entails non-trivial consequences. In particular, the usual relation between the self-trapped state radius and energy shift is violated. The results qualitatively explain anomalous features of the luminescence spectrum and kinetics recently observed by Yu.V. Malyukin et al. [Pis'ma JETP 58 (1993) 385; JETP 107 (1995) 812] for self-trapped states in molecular chains (J-aggregates) incorporated in an organic matrix.     

On the kinetic equations of a system of one-dimensional hard rods

The hydrodynamical approximation to an infinite system of one-dimensional identical hard rods interacting through elastic collisions, is shown to be an integrable system possessing a one-parameter family of nonlinear Hamiltonian structures.     

Quasidegenerate self-trapping in one-dimensional charge transfer exciton

The self-trapping by the nondiagonal particle-phonon interaction between two quasidegenerate energy levels of the excitonic system is studied. We propose this is realized in the charge-transfer exciton, where the directions of the polarization give the quasidegeneracy. It is shown that this mechanism, unlike the conventional diagonal one, allows a coexistence and resonance of the free and self-trapped states even in one-dimensional systems and a quantitative theory for the optical properties (light absorption and time-resolved luminescence) of the resonating states is presented. This theory gives a consistent resolution for the long-standing puzzles in quasi-one-dimensional compound A-PMDA.     

Bending–torsional flutter of a cantilevered pipe conveying fluid with an inclined terminal nozzle

Stability analysis of a horizontal cantilevered pipe conveying fluid with an inclined terminal nozzle is considered in this paper. The pipe is modelled as a cantilevered Euler–Bernoulli beam, and the flow-induced inertia, Coriolis and centrifugal forces along the pipe as well as the follower force induced by the jet-flow are taken into account. The governing equations of the coupled bending–torsional vibrations of the pipe are obtained using extended Hamilton's principle and are then discretized via the Galerkin method. The resulting eigenvalue problem is then solved, and several cases are examined to determine the effect of nozzle inclination angle, nozzle aspect ratio, mass ratio and bending-to-torsional rigidity ratio on flutter speed of the system.     

Backscattering in the one-dimensional many-fermion system

The Sawada Hamiltonian model is generalized to include the backscattering interaction in a one-dimensional many-fermion system. The collective excitations of the particle-density fluctuations and the backscattering dielectric function are obtained. It is shown that the giant Kohn anomaly of the longitudinal phonon spectrum, observed in the quasi-one-dimensional conductors, is qualitatively reproduced within the present approach.     

Density of states and Friedel sum rule in one- and quasi-one-dimensional wires

We analyze the relation between the density of states obtained from the energy derivative of the Friedel phase and that obtained from the Green's function of one- and quasi-one-dimensional wires with a double δ-potential. In the case of repulsive δ-potentials (in both one- and quasi-one-dimension), we show that the local Friedel sum rule is valid when a correction term is included. Various properties of the one-dimensional local density of states are also discussed. In the case of attractive δ-potentials in a quasi-one-dimensional wire, it is well known that the transmission probability may exhibit a Fano resonance (due to a zero-pole pair). In this case, we show that the local Friedel sum rule is valid provided that the tail of the quasibound state is taken into account by the integrated local density of states. In addition, we show that the density of states in a Fano resonance always has a Lorentz shape with peak position at the resonance energy regardless of the (Fano) asymmetry parameter.