"On positive local solutions of nonlinear parabolic Ito equations"

Speaker: 

Professor Paul Chow

Institution: 

Wayne State University

Time: 

Tuesday, October 21, 2008 - 11:00am

Location: 

MSTB 254

For a class of semilinear stochastic parabolic equations of Ito type, under suitable conditions, we shall prove the existence of positive local solutions and their Lp-moments will blow up in a finte time for any p greater or equal to one.

An upper bound for the dimension of q-ary trace codes

Speaker: 

Phong Le

Institution: 

UCI

Time: 

Tuesday, October 21, 2008 - 2:00pm

Location: 

RH 306

Extending results of Van Der Vlugt,
I shall derive a new non-trivial upper bound for the dimension of trace
codes connected to algebraic-geometric codes. Furthermore, I will deduce
their true dimension if certain conditions are satisfied. Finally,
potential areas of improvement and other related results will be outlined.

Phase transition and universality for homopolymers based on stable walks.

Speaker: 

Professor Nicola Squartini

Institution: 

UCI

Time: 

Tuesday, October 14, 2008 - 11:00am

Location: 

RH 306

We consider a polymer measure based on random walks which are based on sums of iid stable random variables.
A Gibbs measure is defined which models an attraction to the origin for these walks. A phase transition occurs as the the strength of the attraction to the origin occurs.
We examine various "thermodynamic" quantities and show they are all related to each other in a simple way and exhibit universality.

Lagrangian Coherent Structures: Hurricanes, Ocean Dynamics, Jellyfish

Speaker: 

Carl F. Braun Professor of Engineering and Control Jerry Marsden

Institution: 

Caltech

Time: 

Thursday, October 23, 2008 - 3:00pm

Location: 

NS2 1201

Lagrangian coherent structures (LCS) are best described as moving curves in a fluid that separate particles that have qualitatively different trajectories. For instance, particles that circulate in an ocean bay have a separate behavior from particles that go on by the bay and don't get caught up in the circulation. Interestingly, these two classes of particles are separated by a sharp, but moving curve. Similar structures are found in Hurricanes: which particle are going to get swept up in the Hurricane and which don't? Likewise in Jellyfish, some particles enter the underbelly of the jellyfish and bring nutrients, while others are swept downstream to help propel the jellyfish. The way blood flows over a clot, as revealed by LCS can indicate whether or not the clot is dangerous. This lecture will give examples of this sort, explain how the LCS are computed and are connected with other mathematical constructions, such as Smale horseshoes in dynamical systems.

DMOC: Discrete Mechanics and Optimal Control

Speaker: 

Carl F. Braun Professor of Engineering and Control Jerry Marsden

Institution: 

Caltech

Time: 

Wednesday, October 22, 2008 - 4:00pm

Location: 

RH 306

People and Nature often try to optimize things; find the shortest route to the grocery store, find the most efficient way to throw a discus, cats turning themselves over efficiently, etc. Optimal control is about finding control forces to perform optimal ways of carrying out a task. Many such systems are mechanical and special techniques for computing optimal controls in mechanics will be presented. These techniques are based on recent progress in discrete mechanics. The techniques will be illustrated by systems such as falling cats, reorienting a network of satellites, optimal space mission design, systems with constraints (such as a satellite with momentum wheels), helicopter dynamics, and efficient 2D and 3D robotic walkers.

Challenges in Combinatorial Scientific Computing

Speaker: 

Professor John Gilbert

Institution: 

UCSB

Time: 

Monday, April 6, 2009 - 4:00pm

Location: 

RH306

Computation on large combinatorial structures -- graphs, strings,
partial orders, etc. -- has become fundamental in many areas of data
analysis and scientific modeling. The field of high-performance
combinatorial computing, however, is in its infancy. By way of
contrast, in numerical supercomputing we possess standard algorithmic
primitives, high-performance software libraries, powerful
rapid-prototyping tools, and a deep understanding of effective
mappings of problems to high-performance computer architectures.

This talk will describe several challenges for the field of
combinatorial scientific computing in algorithms, tools,
architectures, and mathematics. I will draw examples from several
applications, and I will highlight our group's work on
high-performance implementation of algebraic primitives for
computation on large graphs.

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