Georgia Institute of Technology College of Sciences

The empirical mode decomposition (EMD) was a method developed by Huang et al as an alternative approach to the traditional Fourier and wavelet techniques for studying signals. It decomposes signals into finite numbers of components which have well behaved intataneous frequency via Hilbert transform. These components are called intrinstic mode function (IMF). Recently, alternative algorithms for EMD have been developed, such as iterative filtering method or sparse time-frequency representation by optimization. In this talk we present our recent progress on iterative filtering method. We develop a new local filter based on a partial differential equation (PDE) model as well as a new approach to compute the instantaneous frequency, which generate similar or better results than the traditional EMD algorithm.

The Vlasov-Poisson and Vlasov-Maxwell equations possess various variational formulations1 or action principles, as they are generally termed by physicists. I will discuss a particular variational principle that is based on a Hamiltonian-Jacobi formulation of Vlasov theory, a formulation that is not widely known. I will show how this formu- lation can be reduced for describing the Vlasov-Poisson system. The resulting system is of Hamilton-Jacobi form, but with nonlinear global coupling to the Poisson equation. A description of phase (function) space geometry will be given and comments about Hamilton-Jacobi pde methods and weak KAM will be made.Supported by the US Department of Energy Contract No. DE-FG03- 96ER-54346.H. Ye and P. J. Morrison Phys. Fluids 4B 771 (1992).D. Pfirsch, Z. Naturforsch. 39a, 1 (1984); D. Pfirsch and P. J. Morrison, Phys. Rev. 32A, 1714 (1985).

Emory University, the Georgia Institute of Technology and Georgia State University, with support from the National Security Agency and the National Science Foundation, are hosting a series of 9 mini-conferences from November 2010 - April 2013. The fourth in the series will be held at Georgia State University on November 5-6, 2011. This mini-conference's featured speaker is Dr. Bela Bollobas, who will give two one-hour lectures. Additionally, there will be five one-hour talks and seven half-hour talks given by other invited speakers. See all titles, abstracts, and schedule.

This is the first in the series of two talks aimed to discuss a recent work of Ontaneda which gives a poweful method of producing negatively curved manifolds. Ontaneda's work adds a lot of weight to the often quoted Gromov's prediction that in a sense most manifolds (of any dimension) are negatively curved.