Space–time wave packets can propagate invariantly in free space with arbitrary group velocity thanks to the spatio-temporal correlation. Here it is proved that space–time are stable dispersive media as well and from spread time caused by material dispersion. Furthermore, law of anomalous refraction for generalized weakly situation. These results reveal new potential applications real media.

The ultrafast optical Kerr effect (OKE) is widely used to investigate the structural dynamics and interactions of liquids, solutions, solids by observing their intrinsic nonlinear temporal responses through nearly collinear four-wave mixing. Non-degenerate mixing schemes allow for background free detection can provide information on interplay between a material’s internal degrees freedom. Here,...

We study the scale up problem for ow in porous media. The general nature of this problem is outlined, leading to a discussion of assumptions on random elds appropriate for the description of geological heterogeneities. The main point of this paper is to use direct numerical simulation to evaluate the ensemble averages describing uid dispersion, for ow in porous media. The relation between ensem...

This paper presents a general approach for the stability analysis of the time-domain finite-element method (TDFEM) for electromagnetic simulations. Derived from the discrete system analysis, the approach determines the stability by analyzing the root-locus map of a characteristic equation and evaluating the spectral radius of the finite element system matrix. The approach is applicable to the T...