MenuEvents for 10/31/2018 from all calendars
Inverse Problems and Machine Learning
Time: 12:00PM - 1:00PM
Location: BLOC 628
Speaker: Dr. Teemu Saksala, Rice University, Department of computational and applied mathema
Title: Seeing inside the Earth with micro earthquakes
Abstract: Earthquakes produce seismic waves. They provide a way to obtain information about the deep structures of our planet. The typical measurement is to record the travel time difference of the seismic waves produced by an earthquake. If the network of seismometers is dense enough and they measure a large number of earthquakes, we can hope to recover the wave speed of the seismic wave from the travel time differences. In this talk we will consider geometric inverse problems related to different data sets produced by seismic waves. We will state uniqueness results for these problems and consider the mathematical tools needed for the proofs. The talk is based on joint works with: Maarten de Hoop, Joonas Ilmavirta, Matti Lassas and Hanming Zhou.
Noncommutative Geometry Seminar
Time: 2:00PM - 2:50PM
Location: BLOC 628
Speaker: Zhenhua Wang, University of Houston
Title: Noncommutative topology and operator *-algebras
Abstract: An operator $*$-algebra is an operator algebra with a completely isometric conjugate linear involution. In this talk, we will talk about general theory of operator $*$-algebras such as characterizations of operator $*$-algebras, the relationship to their $C^*$-covers and real positivity. In the second part of my talk, noncommutative topology in the involutive setting will be discussed. This is joint work with David Blecher.
Numerical Analysis Seminar
Time: 3:00PM - 4:00PM
Location: BLOC 628
Speaker: Juan-Pablo Borthagaray, University of Maryland
Title: Finite elements for fractional diffusion: towards nonlinear problems
Abstract: In this talk we consider problems involving the integral fractional Laplacian on bounded domains. The first part is devoted to analysis of linear problems; we discuss regularity of solutions, analyze direct finite element implementations and derive convergence rates. Afterwards we discuss two nonlinear problems: the fractional obstacle problem and the computation of nonlocal minimal surfaces. The integral fractional Laplacian is a nonlocal operator given by a singular integral (defined in the principal value sense). Therefore, suitable quadrature is required to handle the singularity of the kernel. Nonlocality originates additional difficulties, such as the need to cope with integration on unbounded domains and full stiffness matrices. Independently of the smoothness of the domain and the data, solutions to the problems under consideration possess a limited Sobolev regularity. In order to enhance the order of convergence of the finite element approximations, we introduce suitably defined weighted Sobolev spaces. This, in turn, leads to the consideration of discrete solutions on graded meshes and permits to obtain optimal convergence rates in two-dimensional domains.
Groups and Dynamics Seminar
Time: 3:00PM - 4:00PM
Location: BLOC 220
Speaker: Constantine Medynets, US Naval Academy
Title: Continuous Orbit Equivalence Rigidity
Abstract: In the 1980s, Mike Boyle proved that whenever two minimal Z-actions on the Cantor set are continuous orbit equivalent, they are automatically conjugate. In the talk, we will discuss the phenomenon of continuous orbit equivalence rigidity and what systems are known to exhibit it.
AMUSE
Time: 6:00PM - 7:00PM
Location: BLOC 220
Speaker: Dr. Kamran Entesari, Department of Electrical&Computer Engineering, Texas A&M
Title: Maxwell’s equations and electromagnetic wave propagation
Abstract: The physical meaning behind each of four Maxwell’s equations and their mathematical representation using vector calculus are first presented. Then , electromagnetic wave equations are derived using Maxwell’s equations and their solutions along with their practical implications are investigated.
