Past Events

Monday April 17, 2017
3 p.m.: SIAM general body meeting

Thursday February 23, 2016
3:30 p.m.: Colloquium talk by Dr. Rich Lehoucq from Sandia National Laboratory:

Title:
A Mixed Finite Element Method for Regularizing the Optical Flow Constraint

Author:
Rich Lehoucq
Sandia National Laboratory

Abstract:
My presentation introduces a mixed finite element method for the estimation of the velocity in the optical flow constraint, i.e., an advection equation. The estimation problem is well-known to be undetermined because the velocity vector cannot be recovered from the scalar field advected unless further restrictions on the flow, or motion, are imposed. If we suppose that the velocity is solenoidal, a well-defined least squares problem with a minimizing velocity results. Equivalently,
we have imposed the constraint that the underlying motion is isochoric. We then demonstrate that the resulting least squares system is ill-posed and regularize via a mixed formulation of the Poisson equation. Standard results for the Poisson equation demonstrate that the regularized system is well-posed and has a stable finite element approximation. A numerical example demonstrating the procedure is given. This is joint work with Dan Turner, Sandia National Labs.

Monday November 14, 2016
3:30 p.m.: Colloquium talk by Dr. Russell Hewett from Total E&P Research and Technology:

Title:
Computational and mathematical challenges in industrial scale seismic imaging

Author:
Russell J. Hewett
Research Scientist, Computational Science and Engineering Dept., Total E&P Research and Technology USA

Abstract:
In this talk I will address the computational and mathematical challenges presented by the seismic inverse problem known as full waveform inversion, where empirical observations of wave propagation are used to recover the earth’s structure. I will start from a simple formulation of the problem and gradually increase the complexity along many axes, considering advances in numerical techniques, geophysical need, HPC hardware and programming models, and the evolution of oil and gas exploration. Along the way I will highlight new developments in these areas, including our recent work on high frequency 3D Helmholtz solvers and recent developments in discontinuous Galerkin solvers in seismic contexts.

5:30 p.m.: A panel discussion titled “Careers in Sciences after Ph.D” featuring speakers from

Dr. Maria Cristina Pereyra from University of New Mexico

Dr. Michelle Hummel from Sandia National Laboratory

Dr. Russell Hewett from Total E&P

Monday September 19, 2016
3:30 p.m.: “A coupling strategy for nonlocal and local diffusion models” talk by Dr. Marta D’Elia from Sandia National Lab