## Seminars and Colloquia by Series

### Alice in Königsberg

Series
Other Talks
Time
Thursday, October 22, 2020 - 20:00 for 30 minutes
Location
ONLINE at https://zoom.us/j/93502013825
Speaker
Evans Harrell and GT Club Math studentsGeorgia Tech

This skit recounts one of the foundation stories of mathematics, the puzzle of the Seven Bridges of Königsberg, solved by Euler in 1726.  Except that it all takes place in a mad courtroom, and you are the jury!

### Mathapalooza After Dark!

Series
Other Talks
Time
Monday, March 16, 2020 - 19:00 for 2 hours
Location
Highland Ballroom, 644 North Highland Ave.
Speaker

### (Oral Exam) Mathematical Modeling and Analysis of Multidimensional Data

Series
Other Talks
Time
Tuesday, April 30, 2019 - 13:00 for 1.5 hours (actually 80 minutes)
Location
Skiles 005
Speaker
Yuchen Roy He GT Math

Multidimensional data is ubiquitous in the application, e.g., images and videos. I will introduce some of my previous and current works related to this topic.
1) Lattice metric space and its applications. Lattice and superlattice patterns are found in material sciences, nonlinear optics and sampling designs. We propose a lattice metric space based on modular group theory and
metric geometry, which provides a visually consistent measure of dissimilarity among lattice patterns.  We apply this framework to superlattice separation and grain defect detection.
2) We briefly introduce two current projects. First, we propose new algorithms for automatic PDE modeling, which drastically improves the efficiency and the robustness against additive noise. Second, we introduce a new model for surface reconstruction from point cloud data (PCD) and provide an ADMM type fast algorithm.

### Oral Exam: On Radial Symmetry of Uniformly Rotating/ Stationary Solutions to 2D Euler Equation

Series
Other Talks
Time
Tuesday, April 23, 2019 - 15:00 for 1 hour (actually 50 minutes)
Location
Skiles 006
Speaker
Jaemin ParkGeorgia Institute of Technology

We study whether all stationary solutions of 2D Euler equation must be radially symmetric, if the vorticity is compactly supported or has some decay at infinity. Our main results are the following:

(1) On the one hand, we are able to show that for any non-negative smooth stationary vorticity  that is compactly supported (or has certain decay as |x|->infty), it must be radially symmetric up to a translation.

(2) On the other hand, if we allow vorticity to change sign, then by applying bifurcation arguments to sign-changing radial patches, we are able to show that there exists a compactly-supported, sign-changing smooth stationary vorticity that is non-radial.

We have also obtained some symmetry results for uniformly-rotating solutions for 2D Euler equation, as well as stationary/rotating solutions for the SQG equation. The symmetry results are mainly obtained by calculus of variations and elliptic equation techniques. This is a joint work with Javier Gomez-Serrano, Jia Shi and Yao Yao.