WVU Math Colloquia
Mondays at 4pm EDT
Armstrong Hall 315
zoom link (pass euclid2022)
The 2022-2023 WVU Math Colloquium is organized by Chris Ciesielski, Robert Mnatsakanov and Casian Pantea.
Talks are usually held on Mondays at 4pm in Armstrong Hall 315 (in some cases we will schedule the seminar at different days/times, to accommodate speakers).
If you'd like to suggest speakers for the fall semester please contact Chris, Robert, or Casian.
Schedule
| date | speaker | institution | title | notes | |
|---|---|---|---|---|---|
| September 15 | Dehua Wang | University of Pittsburgh | Elastic effects on vortex sheets and vanishing viscosity | 2:30pm, 315 ARM | |
| October 17 | Farhad Jafari | University of Minnesota | Variational Problems, Moment Sequences and Positive Definiteness | ||
| October 24 | Tóth János | Budapest University of Technology and Economics | The concept of reaction extent | ||
| October 31 | Zi-Xia Song | University of Central Florida | Coloring Graphs with Forbidden Minors | ||
| November 14 | Benjamin Bagozzi | University of Delaware | Understanding the Politics of Information Access in Big Data Contexts |
Abstracts
Dehua Wang
Elastic effects on vortex sheets and vanishing viscosity
Elasticity is important in continuum mechanics with a wide range of applications and is challenging in analysis. In this talk we shall first review some basic mathematical results and then discuss some special elastic effects in fluid flows. The first elastic effect is the stabilizing effect of elasticity on the vortex sheets in compressible elastic flows. Some recent results on linear and nonlinear stability of compressible vortex sheets will be presented. The second effect is on the vanishing viscosity process of compressible viscoelastic flows in the half plane under the no-slip boundary condition. Our results show that the deformation tensor can prevent the formation of strong boundary layers. The talk is based on the recent joint works with several collaborators.
Farhad Jafari
Variational Problems, Moment Sequences and Positive Definiteness
Our ability to reformulate many problems in science and engineering in terms of variational (and control) problems continue to keep this area of mathematics current and of great interest. In this presentation we reformulate these problems as problems in measure theory and use moment methods to study them. Relating variational problems to moment methods has brought new interest in moment methods, moment completion problems and algebras of rational functions. This talk will connect these areas and (briefly) will show applications of moment methods to reconstruction problems in tomography.
Tóth János
The concept of reaction extent
The concept of reaction extent or the progress of a reaction, advancement of the reaction, conversion, etc. was introduced around 100 years ago. Most of the literature provides a definition for the exceptional case of a single reaction step or gives an implicit definition that cannot be made explicit. Starting from the standard definition we extend the classic definition of the reaction extent in explicit form for an arbitrary number of species and of reaction steps and arbitrary kinetics. Then, we study the mathematical properties (evolution equation, continuity, monotony, differentiability, etc.) of the defined quantity, and connect them to the formalism of modern reaction kinetics. Our approach tries to adhere to the customs of chemists and be mathematically correct simultaneously.
We also show how to apply this concept to exotic reactions: reactions with more than one stationary state, oscillatory reactions, and reactions showing chaotic behavior. With the new definition, one can calculate not only the time evolution of the concentration of each reacting species but also the number of occurrences of the individual reaction events.
This is joint work with Vilmos Gáspár.
Zi-Xia Song
Coloring Graphs with Forbidden Minors
Benjamin Bagozzi
Understanding the Politics of Information Access in Big Data Contexts
Access to information (ATI) systems empower groups and individuals to request information from their governments and obligate these governments to respond, subject to certain legal exemptions. These systems are now in operation in over 100 countries worldwide. The data that are generated by ATI systems can often be characterized as having (i) fine-grained spatio-temporal properties, (ii) extensive amounts of text, (iii) sender-receiver characteristics, and (iv) potential privacy concerns. For political science, such data offer researchers an opportunity to study questions related to government responsiveness, bureaucratic performance, and public accountability at near-unprecedented levels of disaggregation. This presentation highlights the opportunities and challenges associated with ATI data for both data science and political science audiences. Its focus is primarily on Mexico's federal ATI system and over two million associated ATI requests and responses covering the 2003-2020 period. Applications of supervised and unsupervised machine learning tools to the texts of these requests and their responses will be presented, alongside analyses of these request-response measures in relation to government responsiveness in Mexico.