Effect of solid dust particles on the propagation of shock wave in planar and non-planar gasdynamics

The aim of the present study is to analyze the propagation of shock wave along the characteristic path in planar and non-planar unsteady compressible ideal gas flow in presence of small solid dust particles. The analytical solution of the governing quasilinear hyperbolic system is computed in the characteristic plane and it is found that this analytical linear solution in this plane can exhibit non-linear phenomenon in the physical plane. The effect of the dust particles on the evolutionary behavior of the propagating shock wave in ideal gas flow is discussed. The transport equations leading to the evolution of shock wave is determined which introduces the conditions of shock formation. The growth and decay of compressive waves and expansive waves, respectively, in planar and non-planar ideal gas dynamics influenced by the presence of small solid dust particles, is discussed.     

The evolution of the resonant mode in plasma-maser interaction

We study the evolution of the resonant waves considering its interaction with the nonresonant waves and the plasma particles due to plasma-maser effect. The nonlinear dielectric function of the resonant wave is calculated and is found to consist of two parts: the direct and the polarization coupling terms. On the other hand, the nonlinear dielectric function of the nonresonant wave consists only of the direct coupling term. The significance of our results is discussed.     

Effect of the number of defect particles on the structure and dispersion relation of a two-dimensional dust lattice system

The effect of the number of defect particles on the structure and dispersion relations of a two-dimensional (2D) dust lattice is studied by molecular dynamics (MD) simulation. The dust lattice structures are characterized by particle distribution, nearest neighbor configuration and pair correlation function. The current autocorrelation function, the dispersion relation and sound speed are used to represent the wave properties. The wave propagation of the dust lattice closely relates to the lattice structure. It shows that the number of defect particles can affect the dust lattice local structure and then affect the dispersion relations of waves propagating in it. The presence of defect particles has a greater effect on the transverse waves than on the longitudinal waves of the dust lattice. The appropriate number of defect particles can weaken the anisotropy property of the lattice.     

Lamb and torsional waves and their use in flaw detection in tubes

Five separate issues concerning Lamb wave propagation are discussed: (1) the actual motion of the particles in sheet material; (2) the mechanism of the initiation of Lamb waves in plates; (3) the effect of pulse propagation as opposed to continuous waves; (4) wave propagation on the inner and outer surfaces of tubes; and (5) the propagation of waves in tubes at large angles of incidence, beyond the Lamb wave regime.     

Two-wave interaction through the same resonant particles

The possibility of mode-coupling, in a plasma, waves being in resonance with the sample particles is considered. The physical mechanism of this phenomenon is discussed, using as an example two monochromatic finite-amplitude waves: a Langmuir wave and an extraordinary wave. It is shown that the resonant electrons can be an effective channel for energy exchange between the waves.     

On the interaction of two beating electrostatic waves with plasma electrons

This paper is devoted to the study of the interaction of particles with two beating plasma waves. We follow the instructional article by Ott and Dum. According to them, the sum of wave actions during the interaction is constant, supposing the effect of trapped particles on the beat can be neglected. In the present paper, this problem is solved more generally, just for the case of trapped and also untrapped particles in the wave. Our study shows that the sum of wave actions is constant also in the case when the influence of the trapped particles on the amplitudes of two waves was considered. On the contrary this conclusion is not valid if it is supposed that two original waves are amplitude modulated e.g. by the influence of the interaction of the beat with particles. The author is deeply indebted to Dr. Ladislav Krlín for guidance and encouragement throughout the course of this work.     

Numerical Study of the Instability in a Maxwellian Beam-Plasma System II. Many Wave Regime

The relaxation of the beam-plasma system with several preliminarily excited unstable waves in its spectrum is investigated on the basis of computer simulations. The nature of the waves and particles interaction during the instability development is analysed. It is shown that the destroying of the amplitude oscillations of the single wave after saturation in the presence of additional waves is caused by the well known effect of resonance overlapping. A chaotization of the motion of the beam particles occurs even in the case when the amplitudes of the neighbouring waves are small.     

How waves affect the distribution of particles that float on a liquid surface

We study experimentally how waves affect the distribution of particles that float on a liquid surface. We show that clustering of small particles in a standing wave is a nonlinear effect with the clustering time decreasing as the square of the wave amplitude. In a set of random waves, we show that small floaters concentrate on a multifractal set with caustics.     

Quantum modulation of an electron beam in the field of opposite electromagnetic waves

The quantum modulation of an electron beam in the field of opposite electromagnetic waves, at a frequency equal to the difference of the wave frequencies, and its harmonics, is obtained. The depth of the modulation becomes of order one at relatively small intensities of the laser fields (including a real spreading of the beam). In the case of equal frequencies of the waves (when the Kapitza-Dirac effect occurs particles form a beam. An experiment for obtaining a modulated beam of particles at the frequencies of the laser radiation, and its harmonics, as well as for bunching of particles in the field of a standing wave is suggested.     

Relativistic wave and particle mechanics formulated without classical mass

The fact that the concept of classical mass plays an important role in formulating relativistic theories of waves and particles is well-known. However, recent studies show that Galilean invariant theories of waves and particles can be formulated with the so-called ‘wave mass’, which replaces the classical mass and allows attaining higher accuracy of performing calculations [J.L. Fry and Z.E. Musielak, Ann. Phys. 325 (2010) 1194]. The main purpose of this paper is to generalize these results and formulate fundamental (Poincaré invariant) relativistic theories of waves and particles without the classical mass. In the presented approach, the classical mass is replaced by an invariant frequency that only involves units of time. The invariant frequencies for various elementary particles are deduced from experiments and their relationship to the corresponding classical and wave mass for each particle is described. It is shown that relativistic wave mechanics with the invariant frequency is independent of the Planck constant, and that such theory can attain higher accuracy of performing calculations. The choice of natural units resulting from the developed theories of waves and particles is also discussed.     

Recent work at Hiroshima on drift wave turbulence and associated transport

Recent developments in the theory of drift wave turbulence and associated transport phenomena are reviewed within the framework of the weak turbulence theory. Basic physical effects leading to anomalous cross-field transport of particles and energies are discussed in detail for the case of collisionless electrostatic drift waves in a uniform magnetic field. Effects of electro-magnetic perturbations (finite-β effect), magnetic shear and toroidal geometry are also discussed.     

孤立波在一维复合颗粒链中传播特性的模拟研究

采用分子动力学方法模拟研究了孤立波在重轻颗粒相间排列的一维复合颗粒链中的传播特性.结果发现,在轻重颗粒的质量比较大或较小时,散射作用较弱,颗粒的速度和孤立波的速度衰减较慢.在轻重颗粒的质量比为中等时,散射作用较强,颗粒的速度和孤立波的速度衰减较快.孤立波在通过重-轻颗粒界面时,存在有增速效应,可以提高孤立波的传播速度.并且,轻重颗粒的质量比越小增速效应越强.在散射作用和增速效应的共同作用下,改变轻重颗粒的质量比可以调控孤立波在重-轻颗粒链中的传播时间.     

The nonlinear interaction of waves generated by the stimulated Raman scattering with plasma in the PALS experiment

This paper is devoted to the study of the nonlinear interaction of the waves generated by stimulated Raman scattering in plasma. The influence of nonlinear interaction of plasma wave with plasma electrons on the sum of action densities of waves generated by the laser wave is solved. The electron acceleration in the forward and backward wave fields is described. The change of the electric field of the quasimode of forward and backward plasma waves of Raman scattering given by trapping of plasma particles is calculated. Numerical results are calculated for typical parameters of the PALS experiment.     

神经元网络螺旋波诱发机理研究

实验研究发现大脑皮层电活动和信号传播有类似螺旋波的特征.本文利用包含离子通道效应的Hodgkin-Huxley神经元构造规则网络来研究螺旋波的形成机理,利用缺陷阻挡行波的方法在神经元网络中诱导到不同周期的螺旋波,分析了螺旋波产生条件和耦合强度对螺旋波的影响.同时,对脑皮层中螺旋波形成的机理进行了讨论.     

The extended wave-particle duality

The extension of the de Broglie wave hypothesis for particles for which the absolute value of the wave four-vector is not zero is proposed in terms of the so-called 3(2∣n∣+1) and 2∣n∣+1 waves hypothesis. Some theoretical and experimental consequences are discussed.     

Study of fully developed wind wave spectrum by application of quantum statistics

The spectrum of fully developed wind waves is studied by application of the method of quantum statistics. A particle picture of water waves is introduced as an analogy of wave–particle duality. “Water wave particles” are conceived which are similar to phonons for elastic waves in solids. However, due to the property of wave breaking, the number of “water wave particles” in a quantum state is restricted. The spectrum of fully developed wind waves is studied on the basis of the maximum entropy principle. The similarity law of fully developed wind wave spectrum is proved. In the high frequency range, the spectral form is in agreement with the result of observations. In the particle picture, a saturated spectrum is introduced which is in conceptual consistency with the saturated spectrum introduced by Phillips in the wave picture, and the form of which is the same as Phillips’. It is further shown that in the high frequency range the spectrum is only half saturated for fully developed wind waves. The frequency downshifting phenomenon which cannot be explained by wave theory is explained in the particle picture.     

Self-trapping light waves and quanta: Towards an explanation of wave-photon duality

Advances in laser technology have made it possible to discover the light-trapping effect and on the basis of its theory to build up a classical understanding of quantum energy, structure of light.Three unanswered questions are discussed: Why is the amount of quantum energy,E, proportional to the wave frequency? Why does E not depend on the wave intensity? Why is Planck's constant h valid for waves and particles of various kinds? The answer lies, in the case of photons, in the non-linearity of the classical Maxwell equations, which lead to the non-linear wave equation, and which in turn yield the light self-trapping effect. The model based on the non-linearity of Maxwell's equations and self-trapping quantitatively fits Planck's constant and provides answers to the above questions.     

Higher order contribution to the propagation characteristics of low frequency transverse waves in a dusty plasma

Characteristic features of low frequency transverse wave propagating in a magnetised dusty plasma have been analysed considering the effect of dust-charge fluctuation. The distinctive behaviours of both the left circularly polarised and right circularly polarised waves have been exhibited through the analysis of linear and non-linear dispersion relations. The phase velocity, group velocity, and group travel time for the waves have been obtained and their propagation characteristics have been shown graphically with the variations of wave frequency, dust density and amplitude of the wave. The change in non-linear wave number shift and Faraday rotation angle have also been exhibited with respect to the plasma parameters. It is observed that the effects of dust particles are significant only when the higher order contributions are considered. This may be referred to as the ‘dust regime’ in plasma.     

Nonlinear adiabatic models of ion-acoustic waves in dust plasma

Nonlinear adiabatic models of ion-acoustic waves in a dust plasma are developed. The problem of the structure of subsonic periodic and supersonic solitary ion-acoustic waves is exactly solved analytically under the assumption of a constant charge of dust particles; the critical Mach numbers for the solitary wave are determined. The problem of the wave structure is solved numerically for the case when the charge of dust particles was assumed to be variable.     

Nonturbulent stabilization of ion fluxes by the fan instability

Resonant interactions between energetic ion fluxes and wave packets they excite through fan instability are studied using self-consistent 3D simulations to explain the nonlinear wave–particle mechanisms at work and to estimate the energy lost by the flux and its sharing between wave emission and particle heating. The saturation of waves and the relaxation of particles are studied over long time periods. The ions are not only diffusing in the waves but are also trapped simultaneously by several potential wells of large amplitude overlapping waves. Estimates of the ion heating energy and rate are given and compared with space observations.