Inhalt des Dokuments
Absolventen-Seminar • Numerische Mathematik
Verantwortliche Dozenten: |
Prof. Dr. Christian Mehl [1], Prof. Dr. Volker Mehrmann
[2] |
---|---|
Koordination: |
Ann-Kristin Baum |
Termine: | Do 10:00-12:00 in MA
376 |
Inhalt: | Vorträge von
Diplomanden, Doktoranden, Postdocs und manchmal auch Gästen zu
aktuellen
Forschungsthemen |
Datum | Zeit | Raum | Vortragende(r) | Titel |
---|---|---|---|---|
Do 18.04. | 10:15 Uhr | MA
376 | - kein Seminar - | |
Do 25.04. | 10:15 Uhr | MA 376 | Christian
Schröder | Enforcing Solvability of a certain
Nonlinear Matrix Equation |
Do 02.05. | 10:15 Uhr | MA 376 | - kein Seminar
- | |
Do 09.05. | 10:15 Uhr | MA 376 | - kein Seminar
- | |
Do 16.05. | 10:15 Uhr | MA 376 | - kein Seminar
- | |
Do 23.05. | 10:15 Uhr | MA 376 | - kein Seminar
- | |
Do 30.05. | 10:15 Uhr | MA 376
| Christoph Conrads Agnieszka Miedlar | Automated Multilevel Substructuring:
Introduction and Properties Hierarchically enriched adaptive finite element method for PDE eigenvalue/eigenvector approximations |
Do 06.06. | 10:15 Uhr | MA 376 | - kein Seminar
- | |
Do 13.06. | 10:15
Uhr | MA 376 | Linghui
Zeng Vladimir Kostić | Structure And Sign Preserving
Transformations Between Real T-even Quadratics And Real Hamiltonian
Matrices Localisation techniques for eigenvalue problems via diagonal dominance |
Do 20.06. | 10:15 Uhr | MA 376 | Helia Niroomand Rad Sarosh Quraishi | Modeling
the Crosstalk Phenomenon within Electromagnetic Systems Eigenvalue problems arising from FE modeling of squealing disk brake |
Do
27.06. | 10:15 Uhr | MA
376 | Michal Wojtylak Robert Altmann | Low rank perturbations of hermitian
pencils Stopping criteria for flow equations |
Do
04.07. | 10:15 Uhr | MA
376 | Dagmar Leibham Leonhard Batzke | Numerical Methods for
Complex T-even Eigenvalue Problems Low-Rank Perturbations of Alternating Matrix Pencils |
Do 11.07. | 10:15
Uhr | MA 376 | Phi
Ha | Solvability analysis and reformulation of
general Linear Delay Differential-Algebraic Equations
|
Rückblick
- Absolventen Seminar WS 12/13 [3]
- Absolventen Seminar SS 12 [4]
- Absolventen Seminar WS 11/12 [5]
Phi Ha (TU Berlin)
Donnerstag, 11. Juli 2013
Solvability analysis and reformulation of general Linear Delay Differential-Algebraic Equations
Delay differential equations (DDEs) arise in a variety of
applications, including physical systems, biological systems and
electronic networks. If the states of the physical system are
constrained, e.g., by conservation laws or interface conditions, or
some economical interest are involved in the biological model, then
algebraic equations have to be included and one has to analyze delay
differential-algebraic equations (Delay-DAEs).
In this
talk, we present our recent result on the solvability analysis of
general linear Delay-DAEs, i.e., system with linear time variable
coefficients. We propose the method to reformulate a Delay-DAE into
its underlying delay system, which can be used to address structural
properties of the system like existence and uniqueness of a solution,
consistency and smoothness requirements.
In the second
part of the talk, if time permits, we shall consider some spectral
properties of Linear Delay-DAEs and their relations with the
solvability and stability analysis of the system.
This is
the joint work with Volker Mehrmann and Andreas Steinbrecher.
Dagmar Leibham
Donnerstag, 04. Juli 2013
Numerical Methods for Complex T-even Eigenvalue Problems
We investigate when T-even matrix polynomials allow a structure preserving linearization and develop an appropriate condensed form for T-even matrix polynomials. Then a structure preserving numerical method for the complex T-even polynomial eigenvalue problems is presented.
Leonhard Batzke (TU Berlin)
Donnerstag, 04. Juli 2013
Low-Rank Perturbations of Alternating Matrix Pencils
Many applications give rise to alternating matrix pencils. In this talk, structure-preserving low-rank perturbations of alternating (i.e. symmetric / skew-symmetric) matrix pencils will be investigated. While unstructured perturbations are well-understood, in the structured case not all canonical forms are 'allowed' for the perturbed pencil. Hence, the generic result deviates substantially from the unstructured case. We will derive a generic canonical form for alternating matrix pencils under symmetric rank-1 and skew-symmetric rank-2 perturbations.
Michal Wojtylak (Jagiellonian University)
Donnerstag, 27. Juni 2013
Low rank perturbations of hermitian pencils.
Let A+zE be a liner pencil with matrices A,E being
hermitian-symmetric. The following family of linear pencils
A+tB+zE where t is a real parameter and B is a low rank perturbation
of A, will be considered. In particular, the parameter dependence of
the eigenvalues and of the canonical forms will be discussed.
Special attention will be put to the case when the pencil is
silngular for some values of t. In addition, a few facts
infinite-dimensional counterpart of the problem will be recalled.
Robert Altmann (TU Berlin)
Donnerstag, 27. Juni 2013
Stopping Criteria for Flow Equations
One of the key issues in efficient computations is to balance the various error components. This may include discretization, linearization, algebraic, or quadrature errors. In this talk, I give a short overview of a recent paper by A. Ern and M. Vohralik, where stopping criteria are derived for nonlinear diffusion problems. Therein, the technique of flux reconstruction is used to distinguish several error components. In the second part of the talk, I present a first attempt to adopt this method for the unsteady Stokes equation.
Helia Niroomand Rad (Tu Berlin)
Donnerstag, 20. Juni 2013
Modeling the Crosstalk Phenomenon within Electromagnetic Systems
In this talk, after introducing the crosstalk phenomenon in electromagnetic systems, in particular for electrical circuits, we will model the crosstalk for two neighboring close electrical circuits via presenting a coupled bilateral system. This system is obtained by coupling two unilateral subsystems each describing partially the crosstalk in the field theory and in the circuit theory. We will present Maxwell’s equations and modified nodal analysis formalism as the tools to describe the crosstalk in the field and in the circuit theory, respectively.
Sarosh Quraishi (TU Berlin)
Donnerstag, 20. Juni 2013
Eigenvalue problems arising from FE modeling of squealing disk brake Sqealing in a car brake is a very common problem, the origin of which is unstable friction induced self-excited vibration. The simplified governing equation is a quadratic eigenvalue problem with a parameter dependence. The eigenvalues with positive real part correspond to unstable modes which result in brake squeal. In this talk I will present the traditional approach of dimension reduction and a new proper orthogonal decomposition based model reduction which takes into account the parametric dependence of matrices and is more accurate than traditionally used approach, but at the same time computationally more expensive.
Linghui Zeng
Donnerstag, 13. Juni 2013
Structure And Sign Preserving Transformations Between Real T-even Quadratics And Real Hamiltonian Matrices
In this talk, we will give a sufficient and necessary condition for structure and sign preserving transformations between real T-even quadratics and real Hamiltonian matrices.
Vladimir Kostić
Donnerstag, 13. Juni 2013
Localisation techniques for eigenvalue problems via diagonal dominance
From the simple observation of Geršgorin that eigenvalues of a given matrix lie in the union of disks centred in its diagonal entries, many eigenvalue localisation techniques have been developed through the years. In this talk, we will consider a certain unifying approach to this subject via classes of diagonally dominant matrices, and present few general principles that cover large range of singular results published by many authors. In addition, Geršgorin-type localisation technique for generalised eigenvalue problem will be defined and its underlying principles presented. To conclude the talk, some issues concerning stability will be discussed.
Agnieszka Miedlar (TU Berlin)
Donnerstag, 30. Mai 2013
Hierarchically enriched adaptive finite element method for PDE eigenvalue/eigenvector approximations
In this talk we present an adaptive finite element method for PDE
eigenvalue
problems which exploits hierarchical basis functions
to improve the quality of
the approximated eigenpairs. Starting
from the results of Grubiv{s}i'{c} and Ovall
on the reliable and
efficient asymptotically exact a posteriori hierarchical error
estimators in the self-adjoint case,
we explore the possibility
to use the enhanced Ritz values and vectors to restart the iterative
algebraic procedures
within the adaptive algorithm. Using higher
order hierarchical polynomial finite element bases, as
indicated
by Bank and by Ovall and Le Borne, our method yields a structure which
is particularly suitable
for designing computational algorithms
with low complexity. Some preliminary numerical results will
present the potential of this approach.
Christoph Conrads (TU Berlin)
Donnerstag, 30. Mai 2013
Automated Multilevel Substructuring: Introduction and Properties [6]
In this talk we will present Automated Multilevel Substructuring
(AMLS), a method to compute /many/ eigenvalues for large,
sparse generalized eigenvalue problems.
We will introduce
you to the method using an important engineering problem and then we
will walk you through all of the steps of the method. We will also
talk about the useful properties of AMLS and its applications.
Afterwards, you will know about the suffering of the engineers,
a new generalized eigenvalue solver, when you should consider using
AMLS, and what it is able to accomplish. The method will be
illustrated by some practical examples obtained with our
implementation of AMLS.
Christian Schröder (TU Berlin)
Donnerstag, 25. April 2013
Enforcing Solvability of a
certain Nonlinear Matrix Equation
I will talk
about current work with Tobias, Federico and his friend Giacomo about
perturbing the coefficients of the matrix equation
X+AX^{-1}A^T=B
in order to make sure that a solution
exists. I will also show you an application in econometrics (i.e., the
art of predicting Wall Street).
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in.de/pub/numerik/conrads/Conrads_-_AMLS_20130530.pdf