### Seminars and Colloquiums for the week of September 12, 2016

SPEAKER:

Jerzy Dydak, UTK, Monday
Mahir Demir, UTK, Monday
Andrew Marchese, UTK, Tuesday
Tim Krumwiede, UTK , Wednesday
Ken Stephenson, UTK, Wednesday
Christina Edholm, UTK, Thursday
Leo Rebholz, Clemson University, Friday

TEA TIME
3:00 pm – 3:30 pm
Monday, Tuesday, & Wednesday
Room: Ayres 401
Hosted By: Josh Mike and Grace McClurkin

Monday, September 12th

TOPOLOGY/GEOMETRY SEMINAR
TITLE: Hybrid scale spaces and duality II
SPEAKER: Jerzy Dydak, UTK
TIME: 2:30pm – 3:20pm
ROOM: Ayres 114

Most of the talk is based on joint work with my former PhD students: Kyle Austin and Michael Holloway. Its purpose is to investigate the duality between large scale and small scale. It is done by creating a connection between C*-algebras and scale structures.

In the commutative case we consider C*-subalgebras of $C^b(X)$, the C*-algebra of bounded complex-valued functions on $X$. Namely, each C*-subalgebra $\mathscr{C}$ of $C^b(X)$ induces both a small scale structure on $X$ and a large scale structure on $X$. The small scale structure induced on $X$ corresponds (or is analogous) to the restriction of $C^b(h(X))$ to $X$, where $h(X)$ is the Higson compactification.

The large scale structure induced on $X$ is a generalization of the $C_0$-coarse structure of N.Wright. Conversely, each small scale structure on $X$ induces a C*- subalgebra of $C^b(X)$ and each large scale structure on $X$ induces a C*-subalgebra of $C^b(X)$. To accomplish the full correspondence between scale structures on $X$ and C*-subalgebras of $C^b(X)$ we need to enhance the scale structures to what we call hybrid structures. In the noncommutative case we consider C*-subalgebras of bounded operators $B(l_2(X))$.

MATH BIOLOGY SEMINAR
TITLE: Dynamics of Biological Invasions (continued)
SPEAKER: Mahir Demir, UTK
TIME: 2:30pm – 3:20pm
ROOM: Ayres G003

Tuesday, September 13th

STOCHASTICS SEMINAR
TITLE: A point process distance on the space of Persistence Diagrams: Part I
SPEAKER: Andrew Marchese, UTK
TIME: 2:10pm – 3:25pm
ROOM: Ayres 114

We consider the problem of classification of signals. Through the use of delay embedding and persistent homology, we transform signals into the space of persistence diagrams. We introduce a distance on this space inspired by a distance used in the fields of point processes and multi-set filtering problems. Using this distance, we propose classification and clustering schemes on the persistence diagrams, which is then benchmarked on real and synthetic data.

Wednesday, September 14th

COMPUTATIONAL AND APPLIED MATHEMATICS (CAM) SEMINAR
TITLE: Graphene Edge Energy in Bond-Counting Models
SPEAKER: Tim Krumwiede, UTK
TIME: 3:35pm – 4:35pm
ROOM: Ayres 113

Graphene is a material made of carbon atoms arranged in a 2-dimensional hexagonal lattice. It was first produced in sheets at room-temperature in 2004 and has since become a widely studied subject in materials science and physics due to it being both the strongest and most conductive material known to man. I will demonstrate the use of crystal geometry methods to calculate the anisotropic edge energy of graphene as a function over all commensurate edge orientations and that the Wulff shape of this function correctly corresponds with graphene's equilibrium shape. I will also present a result on the energy of non-commensurate edges. These methods can then be used to describe the edge/surface energies for a wide variety of crystals with non-Bravais lattice structure.

ANALYSIS SEMINAR
TITLE: Convergence of Shapes in Conformal Tiling
SPEAKER: Ken Stephenson, UTK
TIME: 3:40pm-4:30pm
ROOM: Ayres 405

I will review the notions associated with traditional tilings of the plane, conformal tilings, subdivision rules, and aggregate tiles. This is in preparation for a second talk in which I'll prove the convergence of aggregate conformal tiles to their traditional tile shapes.

Thursday, September 15th

DIFFERENTIAL EQUATIONS SEMINAR
TITLE: Modeling the Role of Education in Preventing An Outbreak of the Ebola Virus Disease
SPEAKER: Christina Edholm, UTK
TIME: 2:10pm – 3:10pm
ROOM: Ayres 112

In light of the Ebola outbreak in 2014, we worked on an Ebola model during our South Africa Mathematical Sciences Association Masmau program in 2014 and 2015. Our model partitions the population into those who take precautions against contracting the disease and those who do not. We consider new infections arising in both hospital settings as well as in the community, and include transmission from dead bodies and the environment. Our goal is to illustrate role of education in limiting a potential future Ebola outbreaks in Sudan using data and modeling. We considered implications of a new strain with respect to different death rates and recovery rates.

Friday, September 16th

COLLOQUIUM
TITLE: The reduced NS-$\alpha$ model of turbulent flow
SPEAKER: Leo Rebholz, Clemson University
TIME: 3:30pm-4:30pm
ROOM: Ayres 405

We introduce a new, reduced order NS-$\alpha$ (rNS-$\alpha$) model for the purpose of efficient, stable and accurate simulations of incompressible flow problems at high Reynoldsnumbersoncoarsemeshes. Wemotivatethenewmodelasanadaptationofthe well-known NS-$\alpha$ model that is more efficiently computable, then analyze its well- posedness,treatmentofenergy,anddiscussnumericaldiscretizations. Severalnumerical tests are given which reveal remarkable coarse-mesh accuracy for turbulent flow simulations. Finally, we examine sensitivity of the models solutions to the filtering radius.

#### If you are interested in giving or arranging a talk for one of our seminars or colloquiums, please review our calendar.

If you have questions, or a date you would like to confirm, please contact colloquium AT math DOT utk DOT edu

Past notices:

spring_16.html

fall_15.html

###### last updated: May 2018

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