Saltation is an important geological process and the primary source of atmospheric mineral dust aerosols. Unfortunately, no studies to date have been able to precisely reproduce the saltation process because of the simplified theoretical models used. For example, sand particles in most of the existing wind sand movement models are considered to be spherical, the effects of the sand shape on the...

In this paper, we present an original non-linear subdivision scheme suitable for univariate data, plane curves and discrete triangulated surfaces, while keeping the complexity acceptable. The proposed technique is compared to linear subdivision methods having an identical support. Numerical criteria are proposed to verify basic properties, such as convergence of the scheme and the regularity of...

Motivated by observations of supernova SN1987A, various authors have simulated Rayleigh–Taylor (RT) instabilities in the envelopes of core collapse supernovae (for a review, see [1]). The non-radial motion found in these simulations qualitatively agreed with observations in SN1987A, but failed to explain the extent of mixing of newly synthesized Ni quantitatively. Here we present results of a 2...

Mixtures of Gaussian (or normal) distributions arise in a variety of application areas. Many heuristics have been proposed for the task of finding the component Gaussians given samples from the mixture, such as the EM algorithm, a local-search heuristic from Dempster, Laird and Rubin (1977). These do not provably run in polynomial time. We present the first algorithm that provably learns the co...

[1] Using data collected during the Puerto Rico Dust Experiment (PRIDE), we examine the effect of nonspherical phase functions on dust aerosol retrievals from geostationary satellites. We utilize a statistical model based on Scanning Electron Micrograph (SEM) analysis of individual dust particles. Using T-matrix calculations and assuming that dust particles are randomly-orientated oblate sphero...

A particular choice of the time function in the recently presented spherical solution by Dadhich [1] leads to a singularity free cosmological model which oscillates between two regular states. The energy-stress tensor involves anisotropic pressure and a heat flux term but is consistent with the usual energy conditions (strong, weak and dominant). By choosing the parameters suitably one can make...

A model of spheroidal particles is used to calculate the steady-state temperature of dust grains immersed in the interstellar radiation field. It is found that the temperature of non-spherical grains with the aspect ratios a/b < ∼ 2 deviates from that of spheres less than 10 %. More elongated or flattened particles are usually cooler than spheres of the same mass and in some cases the temperatu...