NumPI October 2024

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3 participants
5 discussions

[Indico] Prof. Andreas Frommer, Structure-aware Krylov approximations to generalized Cayley transforms, 25/10/2024, 11:00 Europe/Rome
by fabio.durastante＠unipi.it 23 Oct '24

23 Oct '24

Title: Structure-aware Krylov approximations to generalized Cayley transforms, Speaker(s): Prof. Andreas Frommer, University of Wuppertal, Date and time: 25 Oct 2024, 11:00 (Europe/Rome), Lecture series: Seminar on Numerical Analysis, Venue: Scuola Normale Superiore (Aula Mancini). You can access the full event here: https://events.dm.unipi.it/e/296 Abstract -------- Generalized Cayley transforms arise in implicit numerical integration schemes for ordinary differential equations and differential-algebraic equations. We consider Arnoldi-type methods to approximate the action of such a Cayley transform on a vector and investigate how energy conservation or dissipation can be enforced at the level of each Arnoldi iterate, not just at the level of the exact solution. We also investigate generalizations to higher order collocation methods. Note ---- Reminder of tomorrow's seminar -- Indico :: Email Notifier https://events.dm.unipi.it/e/296

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Difesa dottorato - PhD defense
by Igor SIMUNEC 18 Oct '24

18 Oct '24

Cari tutti, Venerdì 25 ottobre alle 14.30 difenderò la mia tesi di dottorato, intitolata "Advances in polynomial and rational Krylov methods for matrix functions with applications", in Aula Bianchi Lettere (Scuola Normale Superiore). Dopo la difesa ci sarà un piccolo brindisi e rinfresco nel chiostro del Palazzo della Carovana. Chiunque volesse partecipare, o anche soltanto passare per un saluto, è benvenuto! A presto, Igor --- Dear all, On October 25th at 14.30 I will defend my PhD thesis, titled "Advances in polynomial and rational Krylov methods for matrix functions with applications", in Aula Bianchi Lettere (Scuola Normale Superiore). After the defense there will be some refreshments in the internal courtyard of the Palazzo della Carovana. You are all welcome to participate! Best, Igor

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[Indico] Prof. Andreas Frommer, Structure-aware Krylov approximations to generalized Cayley transforms, 10/25/24, 11:00 AM Europe/Rome
by fabio.durastante＠unipi.it 17 Oct '24

17 Oct '24

Title: Structure-aware Krylov approximations to generalized Cayley transforms, Speaker(s): Prof. Andreas Frommer, University of Wuppertal, Date and time: Oct 25, 2024, 11:00 AM (Europe/Rome), Lecture series: Seminar on Numerical Analysis, Venue: Scuola Normale Superiore (Aula Mancini). You can access the full event here: https://events.dm.unipi.it/e/296 Abstract -------- Generalized Cayley transforms arise in implicit numerical integration schemes for ordinary differential equations and differential-algebraic equations. We consider Arnoldi-type methods to approximate the action of such a Cayley transform on a vector and investigate how energy conservation or dissipation can be enforced at the level of each Arnoldi iterate, not just at the level of the exact solution. We also investigate generalizations to higher order collocation methods. -- Indico :: Email Notifier https://events.dm.unipi.it/e/296

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Seminar announcement: A finite element approximation of a simplified model for smart fluids: an error analysis 9/10
by Fabio Durastante 08 Oct '24

08 Oct '24

Good morning, Colleagues in the Analysis section have organized this seminar by Alex Kaltenbach that may be of interest to some of us. The detailed information follows. Best, Fabio Speaker: Alex Kaltenbach, Technische Universität Berlin Seminar: A finite element approximation of a simplified model for smart fluids: an error analysis Date: October 9th at 5:00 pm, Aula Riunioni (Maths Department) Abstract: In this talk, a finite element approximation of the steady $p(\cdot)$-Navier--Stokes equations ($p(\cdot)$ is variable dependent) is examined for orders of convergence by assuming natural fractional regularity assumptions on the velocity vector field and the kinematic pressure. Numerical experiments confirm the quasi-optimality of the \textit{a priori} error estimates (for the velocity). The steady $p(\cdot)$-Navier--Stokes equations are a prototypical example of a non-linear system with variable growth conditions. They appear naturally in physical models for so-called \textit{smart fluids}, \textit{e.g.}, electro-rheological fluids, micro-polar electro-rheological fluids, magneto-rheological fluids, chemically reacting fluids, and thermo-rheological fluids, and have the potential for an application in numerous areas, \textit{e.g.}, in electronic, automobile, heavy machinery, military, and biomedical industry.

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[Indico] Mehdi Najafi Kalyani, A two-dimensional minimum residual technique for accelerating two-step iterative solvers, 04/10/2024, 11:00 Europe/Rome
by leonardo.robol＠unipi.it 02 Oct '24

02 Oct '24

Title: A two-dimensional minimum residual technique for accelerating two-step iterative solvers, Speaker(s): Mehdi Najafi Kalyani, University of Pisa, Date and time: 4 Oct 2024, 11:00 (Europe/Rome), Lecture series: Seminar on Numerical Analysis, Venue: Dipartimento di Matematica (Aula Seminari). You can access the full event here: https://events.dm.unipi.it/e/289 Abstract -------- In this talk, we present a technique to speed up the convergence of a class of two-step iterative methods for solving linear systems of equations. To implement the acceleration technique, the residual norm associated with computed approximations for each sub-iterate is minimized over a certain two-dimensional subspace. Convergence properties of the resulting method will be discussed in detail. It will be further shown that the approach can be developed to solve (regularized) normal equations arising from the discretization of ill-posed problems. Numerical experiments will be disclosed to illustrate the performance of exact and inexact variants of the method for some test problems. -- Indico :: Email Notifier https://events.dm.unipi.it/e/289

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