Multiscale analysis for d+1 dimensional percolation models with d dimensional inhomogeneity.

Speaker: 

Rajinder Mavi

Institution: 

UCI

Time: 

Thursday, April 19, 2012 - 2:00pm to 3:00pm

Location: 

RH 306

We discuss d+1 dimensional percolation models with d dimensional
quasiperiodic disorder. A multiscale scheme is introduced which is suited
to the spatial structure of quasiperiodic disorder. In this case we will
show almost sure stretched exponential decay of correlations as compared
to faster than polynomial decay of correlations obtained for similar
models with random disorder. We mention in this case a disorder-rated
transition of phase structure.

L-functions of p-adic characters

Speaker: 

Daqing Wan

Institution: 

UC Irvine

Time: 

Thursday, April 19, 2012 - 3:00pm to 4:00pm

Location: 

RH440R

Our main question is the p-adic meromorphic continuation of
the L-function attached to a p-adic character for the rational
function field over a finite field of characteristic p. In this talk,
I will explain a new and (hopefully) transparent approach to this
problem. (This is ongoing joint work with Chris Davis).

Mathematical Contest in Modeling (MCM) Results

In February 2012, 6 teams of 3 students from UCI participated in the international Mathematical Contest in Modeling (MCM). The results just came out and all the teams earned certificates, with two teams earning special designations.
 
Austin Fringer (Math+ICS major), Wes Fuhrman (Physics major) and Arturo Vargas (Math major) earned a Meritorious award. This means they were in the top 9% of the 3697 teams in the competition. Only one US team scored higher.
 

The Mathematical Secret of Flight

How is it possible that the 400 squaremeter wings can carry 400 tons at a
wingload of 1 ton per squaremeter in sustained flight in the air? Are you
satisfied with some of the explanations offered in popular science, like
higher velocity and lower pressure on the upper surface of the wing
because it is curved and air there has a longer path to travel than below?
In this talk, we will derive the equations of motion for fluids and
introduce the Euler and the Navier-Stokes equations for fluids. We will

Fast Toric Algorithms Over Local Fields

Speaker: 

Maurice Rojas

Institution: 

Texas A&M University

Time: 

Thursday, April 12, 2012 - 3:00pm to 4:00pm

Location: 

RH440R

We show how to efficiently count exactly the number of solutions of a system of n polynomials in n variables over certain local fields L, for a new class of polynomials systems. The fields we handle include the reals and the p-adic rationals. The polynomial systems amenable to our methods are made up of certain A-discriminant chambers, and our algorithms are the first to attain polynomial-time in this setting. We also discuss connections to Baker's refinement of the abc-Conjecture, Smale's 17th Problem, and tropical geometry. The results presented are, in various combinations, joint with Martin Avendano, Philippe Pebay, Korben Rusek, and David C. Thompson.

The Perona-Malik Equation and its Slow Time Behavior

Speaker: 

Maria Colombo

Institution: 

University of Texas, Austin

Time: 

Thursday, April 19, 2012 - 3:00pm

Location: 

RH 306

The Perona-Malik equation is a celebrated example of nonlinear forward-backward diffusion, introduced in the context of image denoising. It can be viewed as the formal gradient-flow of a functional with a convex-concave integrand. In spite of its mathematical ill-posedness, numerical experiments exhibit better than expected behavior of its solutions.
After a general introduction to the equation itself, we present a few approximation schemes, some classical and some more recent. The approximating solutions show distinct behavior on three time scales (called fast, standard, and slow time). We provide a rigorous explanation for the slow time behavior of the different approximations.
In order to carry out this analysis, we prove an abstract result about passing to the limit in gradient-flows (in the more general context of the theory of maximal slope curves in metric spaces). We are guided by the general principle that "the limit of a family of gradient-flows is the gradient-flow of the limiting functional".

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