CAM Seminar

Computational and Applied Mathematics Seminar

Fall 2020

Mondays at 4:10 p.m. via ZOOM talks

(Note the starting time maybe a few minutes later following the adjusted class times on MWF required by the University)


The CAM Seminar is organized in the ISU Mathematics Department. It brings speakers from inside and outside of ISU, raising issues and exchanging ideas on topics of current interest in the are of computational and applied mathematics.


 


  • September 28

       Title: Nonlocal traffic flow models and the prevention of traffic jams

       Changhui Tan

       Department of Mathematics, University of South Carolina

Abstract: In this talk, I will discuss a family of traffic flow models. The classical Lighthill-Whitham-Richards model is known to have a finite time blowup for all generic initial data, which represents the creation of traffic jams. I will introduce a family of nonlocal traffic flow models, with look-ahead interactions. Such models can be derived from discrete cellular automata models.We show a remarkable phenomenon that the nonlocal slowdown interaction prevents traffic jams, under suitable settings. This talk is based on joint works with Thomas Hamori, Yongki Lee and Yi Sun.

       ZOOM Link:

Join from a PC, Mac, iPad, iPhone or Android device:

    Please click this URL to start or join. https://iastate.zoom.us/j/99977961023
    Or, go to https://iastate.zoom.us/join and enter meeting ID: 999 7796 1023  
 
Join from dial-in phone line:

    Dial: +1 312 626 6799 or +1 646 876 9923
    Meeting ID: 999 7796 1023
    Participant ID: Shown after joining the meeting
    International numbers available: https://iastate.zoom.us/u/acFwTdHvau

 


  • October 05

      Title: CRITICAL THRESHOLDS IN 1D PRESSURELESS EULER-POISSON SYSTEMS WITH VARYING BACKGROUND

       Manas Bhatnagar

       Department of Mathematics, Iowa State University

Abstract: The Euler Poisson equations describe important physical phenomena in many applications such as semiconductor modeling and plasma physics. In this talk, we will advance our understanding of critical threshold phenomena in such systems in the presence of different forces. We will identify critical thresholds in two damped Euler Poisson systems, with and without alignment, both with attractive potential and spatially varying background state. For both systems, we give respective bounds for subcritical and supercritical regions in the space of initial configuration, thereby proving the existence of a critical threshold for each scenario. Key tools include comparison with auxiliary systems, phase space analysis of the transformed system.

       ZOOM Link:


  • October 12

       Title: TBD

       Zhe Fei

       Department of Physics & Astronomy, Iowa State University

       Abstract: TBD

       ZOOM Link:


  • October 19

      Title: TBD

       Changxin Qiu

       Department of Mathematics, Iowa State University

       Abstract: TBD

       ZOOM Link:


  • October 26

       Title: TBD

       Ruoyu Wu

       Department of Mathematics, Iowa State University

       Abstract: TBD

       ZOOM Link:


  • November 02

       Title: TBD

       Wumaier Maimaitiyiming

       Department of Mathematics, UCLA

       Abstract: TBD

       ZOOM Link:


  • November 09

  • November 16

       Title: TBD

       Yongtao Zhang

       Department of Applied and Computational Mathematics and Statistics, University of Notre Dame 

       Abstract: TBD

       ZOOM Link:


  • November 23

 

 



  • August 31 (3:10-4:00pm)

       Title: From integrating to learning dynamics: new studies on Linear Multistep Methods

       Qiang Du

       Applied Physics and Applied Mathematics, and Data Science Institutes, Columbia University

Abstract: Numerical integration of given dynamic systems can be viewed as a forward problem with the learning of unknown dynamics from  available state observations as an inverse problem. Solving both forward and inverse problems forms the loop of informative and intelligent
scientific computing. This lecture is concerned with the application of Linear multistep methods (LMMs) in the inverse problem setting that has
been gaining importance in data-driven modeling of complex dynamic processes via deep/machine learning. While a comprehensive mathematical theory of LMMs as popular numerical integrators of prescribed dynamics has been developed over the last century and has become textbook materials in numerical analysis. there seems to be a new story when LMMs are used in a black box machine learning formulation for learning dynamics from observed states. A natural question is concerned with whether a convergent LMM for integrating known dynamics is also suitable for discovering unknown dynamics. We show that the conventional theory of consistency, stability and convergence of LMM for time integration must be reexamined for dynamics discovery, which leads to new results on LMM that have not been studied before. We present refined concepts and algebraic criteria to assure stable and convergent discovery of dynamics in some idealized settings. We also apply the theory to some popular LMMs and make some interesting observations on their second characteristic polynomials.

       


  • September 07      (Rescheduled to September 21 due to technical issues)

       


  • September 14

       Title: TBD

       Cancelled

       Abstract: TBD

       ZOOM Link:


 

  • September 21

       Title: Complex Geometry and Optimal Transport

       Gabriel Khan

       Department of Mathematics, Iowa State University

Abstract: In this talk, we consider the Monge problem of optimal transport, which seeks to find the most cost-efficient movement of resources. In particular, we study the regularity (i.e. continuity/smoothness) of this transport. In recent work (joint with J. Zhang), we show that there is a connection between this question and the ``anti-bisectional curvature" of certain Kahler metrics. In this talk, we'll discuss several applications of these results (the second of which is joint with F. Zheng). First, we will answer a question in mathematical finance about the regularity of pseudo-arbitrages, which are investment strategies which beat the market almost surely in the long run. Second, by studying the behavior of anti-bisectional curvature along Kahler-Ricci flow, we will be able to show new results about Kahler-Einstein metrics.

ZOOM Link:
Join from a PC, Mac, iPad, iPhone or Android device:

    Please click this URL to start or join. https://iastate.zoom.us/j/92050407935
    Or, go to https://iastate.zoom.us/join and enter meeting ID: 920 5040 7935  
 
Join from dial-in phone line:

    Dial: +1 312 626 6799 or +1 646 876 9923
    Meeting ID: 920 5040 7935
    Participant ID: Shown after joining the meeting
    International numbers available: https://iastate.zoom.us/u/aemRq3Gv0e