Generation of Vortices by Nonlinear Waves on the Surface of a Viscous Liquid

Physics of Wave Phenomena - Time dependence of the average vorticity amplitude is measured for vortices at lattice sites on the surface of water-glycerin solutions after excitation of two...     

Influence of an Octupole Arrangement of Electrodes on Drift Waves

In order to influence drift waves an octupole arrangement of electrodes is placed in direct vicinity of the plasma. By applying sinusoidal signals with proper phase shift to th electrodes synchronisation of drift waves is observed. The width of the synchronisation area is taken to quantify the interaction of the electrodes with the plasma. It turns out that the synchroniseability strongly depends on the frequency, amplitude and phase shift and has to be interpreted as spatiotemporal effect.     

Direct Observation of Magnetic Vortices in Superconductors Using Electron Waves

The development of a coherent field-emission electron beam has made it possible to observe microscopic magnetic lines of force by detecting the electron-wave phase shifts that are due to vector potentials. Electron-holographic interference microscopy has been used to observe magnetic lines of force of magnetic vortices in superconductors, and Lorentz microscopy has been used to observe the dynamics of the vortices. The observation of vortices not only helps us understand the microscopic mechanism of flux pinning, which holds the key to practical applications of superconductors, but also clarifies fundamental phenomena of superconductivity which have implications for more general physical phenomena.     

Existence of Shear Horizontal Surface Waves in a Magneto-Electro-Elastic Material

The existence of shear horizontal surface waves in a magneto-electro-elastic （MEE） half-space with hexagonal （6mm） symmetry is investigated. The surface of the MEE half-space is mechanically free, but subjected to four types of electromagnetic boundary conditions. These boundary conditions are electrically open/magnetically closed, electrically open/magnetically open, electrically closed/magnetically open and electrically closed/magnetically dosed. It is shown that except for the electrically open/magnetically closed condition, the three other sets of electromagnetic boundary conditions allow the propagation of shear horizontal surface waves.     

Surface Plasma Waves at a Rough Interface of a Solid

The dispersion law for surface polaritons in an inhomogeneous plasma is obtained and studied. The plasma is formed by surface electron states at the interface of a solid under conditions where the irregularity scale is much greater than the wavelength. It is shown that the irregularity of the plasma results in spatial dispersion of surface electrostatic oscillations.     

局部激励法产生靶波来消除螺旋波

提出采用局部激励方法产生靶波来消除抑制激发介质中的漂移(和稳定的)螺旋波．通过在系统中任意选择一个格点进行采样，将采样格点信号反馈到系统局部区域可产生一个稳定的靶波．数值计算表明：该方法可以消除均匀和非均匀介质(扩散系数随时间或空间变化)中的螺旋波(稳定旋转的螺旋波和漂移的螺旋波)，并且对于时空噪声具有一定的抗干扰性．     

Unstable Surface Waves in Running Water

We consider the stability of periodic gravity free-surface water waves traveling downstream at a constant speed over a shear flow of finite depth. In case the free surface is flat, a sharp criterion of linear instability is established for a general class of shear flows with inflection points and the maximal unstable wave number is found. Comparison to the rigid-wall setting testifies that the free surface has a destabilizing effect. For a class of unstable shear flows, the bifurcation of nontrivial periodic traveling waves is demonstrated at all wave numbers. We show the linear instability of small nontrivial waves that appear after bifurcation at an unstable wave number of the background shear flow. The proof uses a new formulation of the linearized water-wave problem and a perturbation argument. An example of the background shear flow of unstable small-amplitude periodic traveling waves is constructed for an arbitrary vorticity strength and for an arbitrary depth, illustrating that vorticity has a subtle influence on the stability of free-surface water waves.     

Bragg Scattering of Surface Waves by a Photo-Induced Array

A pattern of spots of light projected on to a semiconductor wafer creates an array of scatterers that can diffract millimeter-wavelength surface waves through 90° in agreement with the expression for Bragg reflection.     

Ring Waves on the Surface of a Liquid in a Coulomb Field

Technical Physics - The realization laws of instability of ring waves on the surface of an electroconductive liquid in a Coulomb field are studied. The relation is derived, which links the...     

Fluid Mixing Enhanced by Surface Acoustic Waves in a Micro-Cavity

Acoustical Physics - One big challenge in micro-fluidic systems is that the mixing efficiency by molecular free diffusion is too low, especially when the viscosity of the fluids is high. In this...     

Zero Surface Tension Limit of Viscous Surface Waves

We consider the free boundary problem for a layer of viscous, incompressible fluid in a uniform gravitational field, lying above a rigid bottom and below the atmosphere. For the “semi-small” initial data, we prove the zero surface tension limit of the problem within a local time interval. The unique local strong solution with surface tension is constructed as the limit of a sequence of approximate solutions to a special parabolic regularization. For the small initial data, we prove the global-in-time zero surface tension limit of the problem.     

八级形变系统的集体运动

利用一组内部坐标和三个欧拉角描述八极形变系统的集体运动,动能被分解成三部分:体坐标系下的形变振动,体坐标系围绕实验室系的转动以及振动和转动的耦合.量子化的动能算符被导出,一些特殊八极形变下的集体谱被讨论.     

Waves in the Faraday Chiral Media. II. Surface Waves

The propagation of surface waves directed by a plane boundary of the half-space of the Faraday chiral medium (chiroplasma or chiroferrite) is studied in the Voigt configuration. The frequency dependences of the wave parameters are investigated. Conditions of critical propagation regimes are determined.     

Exact Solitary Wave Solutions of Surface Waves in a Convecting Fluids

In the standard Painlevé analysis, the singular manifold can be extended to many different forms because of its arbitrariness. Using some kinds of standard and nonstandard truncation approaches for the extended singular manifolds to a convecting fluid, we can obtain abundant solitary wave structures.     

Excitation of Surface Acoustic Waves and Lamb Waves at Superhigh Frequencies in a Diamond-Based Piezoelectric Layered Structure

Acoustical Physics - The authors have carried out an experimental and theoretical study of the propagation of surface acoustic waves (SAW)—Rayleigh, Sezawa and SH-modes, as well as Lamb waves...     

Standing Waves along a Microwave Generated Surface Wave Plasma

Two surface wave plasma columns, generated by microwave power in argon at gas pressures of 0.05 torr to 330 torr, interact in the same discharge tube to form standing surface waves. Radial electric field Er and azimuthal magnetic field H? outside the discharge tube are measured to be 90° out of phase with respect to axial position and to decay exponentially with radial distance from the tube axis. Maximum light emission occurs at the position of maximum H?, and minimum Er. Electron temperature and density are measured at low pressures with double probes inserted into the plasma at a null of Er. Measured electron densities compare well with those predicted by Gould-Trivelpiece (GT) surface wave theory. Measured electron temperatures are the same order of magnitude as temperatures predicted by positive column theory.