Sebastian Schöps

ECMI 2010 is over

admin — Fri, 30 Jul 2010 13:52:54 +0000

Today was the last day of the 16th European Conference on Mathematics for Industry that took place in the Historische Stadthalle in Wuppertal. As a member of the working group of applied math and numerical anaylsis, I was part of the local organizing committee. I gave a talk in the minisymposium on Electromagnetic Field Computation about fitting reduced order models in magnetoquasistatic field problems (similarly to the talk in Essen) but also on the converegence of the scheme (slides 13ff).

Here you can find the presentation

Multirate Time-Integration with Reduced Order Models (talk)

Computational Magnetics

admin — Tue, 13 Jul 2010 20:20:12 +0000

Next term the chair of numercial analysis, Bergische Universität Wuppertal, offers a lecture on Computational Magnetics. The aim is to develop an Octave software package to simulate magnetoquasistatic fields.

All the typical tasks of applied mathematics will be covered: modeling, software design, coding, testing, simulation und visualization.

EPNC 2010, Essen

admin — Sat, 03 Jul 2010 19:17:00 +0000

The Symposium on Electromagnetic Phenomena in Nonlinear Circuits (EPNC) 2010 was this year in Essen. – A stone’s throw from Wuppertal. I gave another talk on co-simulation. Here the method was applied to an induction motor, as shown in the figure on the right. The coupling is given by extracted inductances, similarily to the method presented at the Compumag 2009. This time the focus was on signal processing; the waveforms are smoothed to allow for large time steps.

Here you can find the presentation

Fitting Lumped Machine Models on the Fly (talk)

Compile Octave on openSUSE 11.x

admin — Wed, 06 Jan 2010 10:52:04 +0000

Currently there is no recent octave package for openSUSE, so I decided to compile it by myself, but due to dependencies this was a rather difficult task. I succeeded by applying the following steps for Octave 3.2.3 on openSUSE 11.2.

1. add some additional sources (if not already available)
sudo zypper ar http://download.opensuse.org/repositories/openSUSE:Factory:Contrib/standard/ openSUSE:Factory:Contrib sudo zypper ar http://download.opensuse.org/repositories/home:/ars3niy:/octave/openSUSE_11.1/ ars3niy:Octave sudo zypper ar http://ftp.gwdg.de/pub/linux/misc/packman/ Packman sudo zypper ar http://ftp.gwdg.de/pub/linux/misc/packman/suse/11.2/ Packman

2. we will need the following packages incl. some devel packages; install:
sudo zypper install bison build fftw3 fftw3-devel flex fltk fltk-devel \ gcc-c++ gcc-fortran glpk glpk-devel libglpk0 \ gmp-devel libgmp3 gnuplot gperf \ ImageMagick libbz2 libbz2-devel \ libcurl libcurl-devel hdf5 hdf5-devel \ libltdl3 ncurses ncurses-devel \ pcre pcre-devel readline readline-devel zlib zlib-devel \ libqrupdate1 libqrupdate1-devel \ Suitesparse Suitesparse-devel \ qhull qhull-devel \ libamd libamd-devel

2b. Add a link to hdf5 library (if necessary)
cd /usr/lib64 sudo ln libhdf5.so libhdf5.so.0

3. install source package; if you like you could compile additionally: libamd Suitesparse qhull …
sudo zypper source-install octave

4. download octave-3.2.3.tar.gz and save it to /usr/src/packages/SOURCES, e.g.
cd /usr/src/packages/SOURCES wget ftp://ftp.octave.org/pub/octave/octave-3.2.3.tar.gz

5. modify octave.spec for the new version
edit /usr/src/packages/SPECS/octave.spec
- change version number (Version: 3.2.3)
- add additional entry to the “%file” section “%{_datadir}/applications/”

6. compile all packages according to their spec files
cd /usr/src/packages/SPECS sudo rpmbuild -ba octave.spec

7. install the packages (this depends on your architecture, e.g. for x86_64)
cd /usr/src/packages/RPMS/x86_64 sudo rpm --install octave*.rpm

ECMI 2010, Wuppertal

admin — Fri, 01 Jan 2010 09:29:50 +0000

My institute organizes from July 26-30, 2010 the next European Conference on Mathematics for Industry (ECMI). The conference is following up ECMI – 2008 in London, UK. As all ECMI conferences, ECMI 2010 will emphasize the role of mathematics as a unique overarching industrial resource.
The registration is open from January, 10th.

Compumag 2009, Florianópolis

admin — Tue, 01 Dec 2009 15:14:33 +0000

I attended to the Compumag 2009 in Florianópolis supported by a travel grant from the DAAD (German Academic Exchange Service). At the conference I showed a nice application of my latest research on co-simulation (together with Andreas Bartel and Herbert De Gersem). The theory is based on the work of Arnold/Günther: “Preconditioned dynamic iteration for coupled differential-algebraic systems” – BIT Numerical Mathematics.

The given application is a multirate framework for the efficient simulation of field/circuit coupled problems. Within this framework, a guarantee for convergence and stability was given by PDAE analysis. It was shown that different time step sizes in different parts of the model can be automatically chosen according to the problem’s dynamics. Finally a finite element model of a transformer coupled to a circuit was given to illustrate the efficiency of the multirate method.

The talk was awarded with a COMPUMAG best paper commendation.

DAAD Research Grant

admin — Fri, 01 May 2009 08:09:50 +0000

Starting in May 2009 I will move for longer periods to Kortrijk to do research at the University of Leuven, supported by a one-year research grant from the DAAD (German Academic Exchange Service).

This research is intended to be an interdisciplinary project. It will be studied from both, the mathematical and engineering point of view and each viewpoint corresponds to the research fields of the working groups. There is on one hand the expertise from Wuppertal in numerical analysis of coupled problems especially with dynamics in multiple time rates and on the other hand the expertise from Leuven in the modeling and computation of field/circuit coupled problems.

Flux Distribution in highly nonlinear Transformer

admin — Fri, 27 Mar 2009 13:09:34 +0000

I have written a simulation package FIDES to test multi rate time integration in coupled electromagnetic field and electric circruit equations. The package is part of the COMSON Demonstrator Platform, using OCTAVE as its interpreter.
Recently I wanted to visualize my results. I used ffmpeg to produce a movie from several plots of the flux distribution inside a transformer.

The results looks like this:
download movie.

SCEE in Finland

admin — Fri, 10 Oct 2008 11:09:21 +0000

I’m back from the SCEE 2008 (Scientific Computing in Electrical Engineering) Conference in Espoo, Finland.
The picture on the left is given to illustrate my coupling approach during my talk about circuits refined by 3-D conductor models. The circuit is given in terms of the modified nodal analysis and the field is discretized by the finite integration technique. The coupled system is introduced and analyzed; numerical results are obtained by co-simulation (“weak coupling”) and monolithic coupling (“strong”). The basic ideas are taken from my thesis, but there are new additional theoretical and numerical results.
Here you can find the presentation and the preprint of the paper.

Simulation of Lumped Electric Circuits Refined by 3-D Magnetoquasistatic Conductor Models (Presentation)
DAE-Index and Convergence Analysis of Lumped Electric Circuits Refined by 3-D Magnetoquasistatic Conductor Models (Preprint, Final Paper)
SCEE Conference (Book of Abstracts, Proceedings)

Master-Thesis

admin — Mon, 25 Feb 2008 18:29:16 +0000

This is my thesis on computational electromagnetics, from the abstract:

Electric circuits contain devices that exhibit multi-physical effects. We may think of electric or magnetic, but also thermal effects. Traditionally these devices are idealized and only one effect is considered, while the others are disregarded. This yields simple laws that mathematically express their transient behaviour, but does not conform to reality. So sometimes these models are not accurate enough and one wants to simulate a particular device with a refined model. We shall present such a refined modelling approach for electromagnetic devices in this treatise.

Coupling and Simulation of Lumped Electric Circuits Refined by 3-D Magnetoquasistatic Conductor Models Using MNA and FIT