Analyticity and Gevrey-class regularity for the Euler equations on domains with boundary

Speaker: 

Vlad Vicol

Institution: 

University of Southern California

Time: 

Thursday, November 12, 2009 - 3:00pm

Location: 

RH 440R

We estimate the domain of analyticity and Gevrey-class regularity of solutions to the Euler equations on the half-space, and on a three-dimensional bounded domain. We obtain new lower bounds for the rate of decay of the real-analyticity radius of the solution, which depend algebraically on the Sobolev norm. In the case of the bounded domain, using Lagrangian coordinates, we prove the persistence of the non-analytic Gevrey-class regularity.

Wave-corpuscle mechanics for elementary charges

Speaker: 

Aleksandr Figotin

Institution: 

UCI

Time: 

Thursday, October 22, 2009 - 2:00pm

Location: 

RH 306

In 1920 Schrodinger inspired by ideas of de Broglie on the material wave introduced his wave mechanics in which a particle is modeled by a wave packet. As it was pointed out by M. Born the interpretation of a particle by a wave packet has problems: the wave packets must in course of time become dissipated, and on the other hand the description of the interaction of two electrons as a collision of two wave packets in ordinary three-dimensional space lands us in grave difficulties. To address those problems we introduce a concept of wave-corpuscle to describe spinless elementary charges interacting with the classical EM field. Every charge interacts only with the EM field and is described by a complex valued wave function over 4-dimensional space time continuum. A system of many charges interacting with the EM field is defined by a local, gauge and Lorentz invariant Lagrangian with a key ingredient - a nonlinear self-interaction term providing for a cohesive force assigned to every charge. An ideal wave-corpuscle is a spatially localized solitary wave which is an exact solution to the Euler-Lagrange equations which are reduced to a certain nonlinear Schrodinger equation. We show that the wave-corpuscle remains spatially localized when it is free or even when it accelerates in a homogeneous electric field. Two or more interacting charges are well defined even when they collide. (joint work with A. Babin)

2D Boussinesq equations with partial viscosity terms on bounded domains

Speaker: 

Kun Zhao

Institution: 

Ohio State University

Time: 

Thursday, October 29, 2009 - 3:00pm

Location: 

RH 440R

The 2D Boussinesq system is potentially relevant to the study of atmospheric and oceanographic turbulence, as well as other astrophysical situations where rotation and stratification play a dominant role. In fluid mechanics, the 2D Boussinesq system is commonly used in the field of buoyancy-driven flow. It describes the motion of incompressible inhomogeneous viscous fluid subject to convective heat transfer under the influence of gravitational force. It is well-known that the 2D Boussinesq equations are closely related to 3D Euler or Navier-Stokes equations for incompressible flow, and it shares a similar vortex stretching effect as that in the 3D incompressible flow. In fact, in vortex formulation, the 2D inviscid Boussinesq equations are formally identical to the 3D incompressible Euler equations for axisymmetric swirling flow. Therefore, the qualitative behaviors of the solutions to the two systems are expected to be identical. Better understanding of the 2D Boussinesq system will undoubtedly shed light on the understanding of 3D flows. In this talk, I will discuss some recent results concerning global existence, uniqueness and asymptotic behavior of classical solutions to initial boundary value problems for 2D Boussinesq equations with partial viscosity terms on bounded domains for large initial data.

Interface Problems and Interface shape classification

Speaker: 

Songming Hou

Institution: 

Louisiana Tech

Time: 

Monday, November 30, 2009 - 4:00pm

Location: 

RH 306

Solving Elliptic equations with sharp-edged interfaces is a challenging problem for most existing methods, especially when the solution is highly oscillatory. Nonetheless, it has wide applications in engineering and science. In the first part of this talk, I will present a non-traditional finite element method for solving matrix coefficient elliptic equations with shape-edged interfaces with 2nd order accuracy in L-infinity norm. In the second part of this talk, I will switch to a topics on interface shape classification, where the goal is to characterize a shape using the least amount of data, to generate a shape library and to match a given shape to one of the shapes in the library after certain rotation, scaling and shifting. I will present a novel method by using the response matrix data, motivated by a direct imaging method for inverse problems.

Operator related function theory and algebraic varieties

Speaker: 

Dr. Greg Knese

Institution: 

UC Irvine

Time: 

Tuesday, November 3, 2009 - 3:00pm

Location: 

RH 306

his talk will be about the interplay between polynomials
whose zero sets interact with the n-torus in C^n (in several natural
ways) and operator related complex function theory (in several natural
settings). Interpolation problems for analytic functions, sums of
(Hermitian) squares formulas, and reproducing kernels all play
important roles. The talk will be relatively non-technical.

Bernstein estimates for weakly coupled fully non-linear elliptic systems

Speaker: 

Prof. Diogo Aguiar Gomes

Institution: 

Mathematics Department of Instituto Superior Tcnico.

Time: 

Tuesday, October 27, 2009 - 3:00pm

Location: 

RH 306

In this talk we discuss Bernstein estimates for weakly fully
non-linear elliptic systems. We are particularly
interested in systems that arise in the stochastic optimal control
problems of hybrid systems. For these a
generalization of Bernstein estimates for first and second derivatives
of classical solutions will be presented.

Variational and PDE Approaches to Texture Modeling and Separation

Speaker: 

Yunho Kim

Institution: 

Visiting Assistant Professor UCI

Time: 

Tuesday, October 13, 2009 - 9:00am

Location: 

RH 340P

This talk will be about a general framework of image processing such as Image denoising, deblurring, segmentation, etc. Variational and also PDE approaches will be considered. Various function spaces will also be mentioned and we will see some advantages and disadvantages of the functions spaces. At the end,
noise - texture characterization or separation techniques will be discussed. Notice that there are no mathematical definitions of noise and texture yet. We will think about this too.

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