Evolution of unidirectional nonlinear wave groups with wide spectra is studied experimentally and numerically. As an example of such an evolution, focusing of an initially wide wave train that is modulated both in amplitude and in frequency, to a single steep wave at a prescribed location along the laboratory wave tank is investigated. When numerous frequency harmonics arrive at the focusing lo...

In field theory, particles are waves or excitations that propagate on the fundamental state. In experiments or cosmological models, one typically wants to compute the out-of-equilibrium evolution of a given initial distribution of such waves. Wave turbulence deals with out-of-equilibrium ensembles of weakly nonlinear waves, and is therefore well suited to address this problem. As an example, we...

Models describing the evolution of long internal waves are proposed that are based on different polynomial approximations of the exact expression for the phase speed of uni-directional, fully-nonlinear, infinitely-long waves in the two-layer model of a density stratified environment. It is argued that a quartic KdV model, one that employs a cubic polynomial fit of the separately-derived, nonlin...

We have evidence that the classical random pinning model , if simulated numerically using a phase evolution scheme pioneered by Littlewood , gives dispersion relationships that are inconsistent with experimental values near threshold. . These results argue for a revision of contemporary classical models of charge density wave transport phenomena. Classically, phase evolution equations are in es...

The lattice Boltzmann method (LBM) was used to analyze two-dimensional (2D) non-Fourier heat conduction with temperature-dependent thermal conductivity. To this end, the evolution of wave-like temperature distributions in a 2D plate was obtained. The temperature distributions along certain parts of the plate, which was subjected to heat generation and constant thermal conductivity condit...

The quasi 2-day wave is known as a strong dynamic perturbation occurring usually after solstice in the middle and upper atmosphere. The excitation mechanism of this transient wave is discussed for years but no clear answe] has been altained. In this paper, propagating characteristics of the 2-day wave are studied based on 8-month temperature measurements from the Microwave Limb Sounde~ (MLS) on...

Methods used in parabolic refraction-diiraction models for computing the evolution of monochromatic waves in the nearshore zone are used to construct a model for spectral wave conditions. The two dimensional spectrum is divided into discrete wave components and the individual wave components are computed simultaneously in the domain using parabolic models for each wave component. Statistical qu...

We present a complete atlas of the Cygnus Loop supernova remnant in the light of [O III] (λ5007), Hα, and [S II] (λλ6717, 6731). We include low-resolution (25) global maps and smaller fields at 6 resolution from observations using the Prime Focus Corrector on the 0.8-m telescope at McDonald Observatory. Despite its shell-like appearance, the Cygnus Loop is not a current example of a Sedov-Taylo...