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Editor: Craig Douglas (douglas-craig@cs.yale.edu)
Associate editor: Gundolf Haase (gundolf.haase@uni-graz.at)
Volume 15, Number 4 (approximately April 30, 2005)
Volume 15, Number 5 (approximately May 31, 2005)
Today's topics:
Important Date
Faculty Position at the University of Stuttgart, Germany
EMG 2005 Preliminary programme on our website
Sixth DOE ACTS Collection Workshop in Berkeley
MG Preprints Found on the Web
An Interesting AMG Concept
This is a great place to let the world know about your results. It is
highly rated for letting the world know about recent graduates' dissertations
and young reserachers' papers... and it is free and open source.
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Date: Tue, 31 May 2005 10:22:21 -0400
From: Craig Douglas
Subject: Important Date
June 15 European Multigrid Conference early registration
See http://pcse.tudelft.nl/emg2005/index.php
June 15 ACTS Workshop proposals due
See http://acts.nersc.gov/events/Workshop2005
-------------------------------------------------------
Date: Fri, 27 May 2005 13:58:19 +0200
From: Thomas Ertl
Subject: Faculty Position at the University of Stuttgart, Germany
Universitaet Stuttgart, Germany
Fakultaet Informatik, Elektrotechnik und Informationstechnik
Faculty Position: Large Systems Simulation.
The University of Stuttgart, Germany invites applications for a Full Professor
(W3 executive position) in Large Systems Simulation. The professor is
expected to conduct excellent research and teaching in the field of simulation
and modeling of large and complex systems and to collaborate closely with
colleagues from mathematics, science and engineering. Candidates are sought
with extensive expertise in some of the following areas: computer science
aspects of scientific computing, parallel algorithms, parallel and distributed
high-performance computing, development and integration of scalable simulation
systems, numerical simulation techniques, discrete and combinatorial methods,
application of simulations in science and engineering. The professor is
expected to contribute to undergraduate and graduate teaching in the degree
programs Computer Science and Software Technology, and in the international
Master of Science program Information Technology, as well as in courses for
programs of other departments. Applicants are asked to send their detailed CV
and accompanying documents to the Dean Prof. Dr.-Ing. habil. Dr. h.c.
mult. P. Kuehn, Fakultaet Informatik, Elektrotechnik und Informationstechnik,
Universitaet Stuttgart, Pfaffenwaldring 47, 70550 Stuttgart, Germany, before
September 15, 2005. For more information please visit
http://www.informatik.uni-stuttgart.de/stellenangebote/SGS.en.html.
Prof. Dr. Thomas Ertl
Institut fuer Visualisierung und Interaktive Systeme
Universitaet Stuttgart
Universitaetsstrasse 38, D-70569 Stuttgart, Germany
Phone: +49-711-7816-331/332, Fax: -340
mailto:Thomas.Ertl@vis.uni-stuttgart.de
http://wwwvis.vis.uni-stuttgart.de/
-------------------------------------------------------
Date: Tue, 31 May 2005 12:58:29 +0200
From: "Heersma, D."
Subject: EMG 2005 Preliminary programme on our website
The scientific programme of the 8th European Multigrid conference on
multigrid, multilevel and multiscale methods, held in Scheveningen/the Hague,
Netherlands from 27-30 September 2005 is now available under
http://pcse.tudelft.nl/emg2005/pages/Preliminary1.pdf
Sincerely,
Cornelis W. Oosterlee,
EMG Organizing Committee
-------------------------------------------------------
Date: Mon, 23 May 2005 15:58:55 -0700
From: Tony Drummond
Subject: Sixth DOE ACTS Collection Workshop in Berkeley
Sixth Workshop on the DOE Advanced Computational Software Collection
Building Robust Scientific and Engineering High-End Computing
Applications
Place: Lawrence Berkeley National Laboratory
Date: August 23-26, 2005
http://acts.nersc.gov/events/Workshop2005
The DOE Advanced CompuTational Software Collection (ACTS Collection,
http://acts.nersc.gov) comprises a set of tools that aim to simplify the
solution of common and important computational problems and have substantially
benefited a wide range of scientific and industrial applications. These
benefits are accounted not only for running efficiently in high performing
computing environments but also realizing computation that would not have been
possible otherwise.
The four-day workshop will present an introduction to the ACTS Collection for
application scientists whose research demand includes either large amounts of
computation, the use of robust numerical algorithms, or combinations of these.
The workshop will include a range of tutorials on the tools (currently
available in the collection and some deliverables from the DOE SciDAC ISICs),
discussion sessions aimed to solve specific computational needs by the
participants, and hands-on practices using NERSC's state-of-the-art computers.
We are planning to organize parallel sessions and group the tutorials by
topics, as follows:
- Direct and Iterative Methods for the solution of linear and non-linear
systems of equations
- PDE's and Multi-level Methods
- Numerical Optimization
- Structured and Unstructured meshes (Generation, Manipulation and
Computation)
- Development of High Performance Computing applications
- Performance monitoring and tuning
- Software Interoperability
This workshop is opened to computational scientists from industry and
academia. Registration fees are fully sponsored by the DOE's Office of
Science. In addition, DOE will sponsor travel expenses for a limited number
of graduate students and postdoctoral fellows. For more information on the
workshop, please contact Tony Drummond at (510) 486-7624 or Osni Marques at
(510) 486-5290.
Important Dates to Remember:
- Proposal submission deadline: June 15, 2005
- Proposal review completed and invitations sent: June 30, 2005
- Attendee confirmation of participation deadline: July 13, 2005
- Travel arrangements completed for all: July 30, 2005
- Workshop Dates: August 23-26, 2005
L. A. Drummond, (Tony)
Staff Scientist
Lawrence Berkeley National Laboratory
One Cyclotron Road
Berkeley, CA 94720
-------------------------------------------------------
Date: Sat, 30 Apr 2005 10:22:18 -0400
From: Craig Douglas
Subject: MG Preprints Found on the Web
Multigrid elliptic equation solver with adaptive mesh refinement
Authors: J. David Brown, Lisa L. Lowe
Comments: 12 pages, 9 figures, accepted for publication in J. Comp. Phys
In this paper we describe in detail the computational algorithm used by our
parallel multigrid elliptic equation solver with adaptive mesh refinement.
Our code uses truncation error estimates to adaptively refine the grid as
part of the solution process. The presentation includes a discussion of the
orders of accuracy that we use for prolongation and restriction operators to
ensure second order accurate results and to minimize computational work.
Code tests are presented that confirm the overall second order accuracy and
demonstrate the savings in computational resources provided by adaptive mesh
refinement.
Editor's Note: See http://arxiv.org/abs/gr-qc/0411112 for the preprint. The
code may be posted to the web later in the summer.
* * * * *
Evolving a puncture black hole with fixed mesh refinement
Authors: Breno Imbiriba, John Baker, Dae-Il Choi, Joan Centrella, David R.
Fiske, J. David Brown, James R. van Meter, Kevin Olson
Comments: 15 pages, 10 figures
Journal-ref: Phys.Rev. D70 (2004) 124025
We present an algorithm for treating mesh refinement interfaces in numerical
relativity. We detail the behavior of the solution near such interfaces
located in the strong field regions of dynamical black hole spacetimes, with
particular attention to the convergence properties of the simulations. In our
applications of this technique to the evolution of puncture initial data with
vanishing shift, we demonstrate that it is possible to simultaneously
maintain second order convergence near the puncture and extend the outer
boundary beyond 100M, thereby a pproaching the asymptotically flat region in
which boundary condition problems are less difficult and wave extraction is
meaningful.
Editor's Note: See http://arxiv.org/abs/gr-qc/0403048 for the preprint.
* * * * *
http://www.llnl.gov/CASC/people/vassilevski/vassilevski_pubs.html
Panayot S. Vassilevski and Ludmil T. Zikatanov, Multiple Vector Preserving
Interpolation Mappings in Algebraic Multigrid, available as Lawrence Livermore
National Laboratory Technical Report UCRL-JRNL-208036, November 2004.
We propose algorithms for the construction of AMG (algebraic multigrid)
interpolation mappings such that the resulting coarse space to span (locally
and globally) any number of a priori given set of vectors. Specific
constructions in the case of element agglomeration AMG methods are given.
Some numerical illustration is also provided.
Editor's Note: See http://www.llnl.gov/CASC/people/vassilevski/vassilevski_pubs.html.
* * * * *
Taejong Kim, Joseph E. Pasciak, and Panayot S. Vassilevski, Mesh independent
convergence of the modified inexact Newton method for a second order nonlinear
problem, available as Lawrence Livermore National Laboratory Technical Report
UCRL-JRNL-206774, September 2004.
In this paper, we consider an inexact Newton method applied to a second order
nonlinear problem with higher order nonlinearities. We provide conditions
under which the method has a mesh-independent rate of convergence. To do
this, we are required to first, set up the problem on a scale of Hilbert
spaces and second, to devise a special iterative technique which converges in
a higher than first order Sobolev norm. We show that the linear (Jacobian)
system solved in Newton's method can be replaced with one iterative step
provided that the initial nonlinear iterate is accurate enough. The closeness
criteria can be taken independent of the mesh size. Finally, the results of
numerical experiments are given to support the theory.
Editor's Note: See http://www.llnl.gov/CASC/people/vassilevski/vassilevski_pubs.html.
* * * * *
Alfio Borzi, Multigrid Methods for Optimality Systems, Habilitation Thesis,
Karl-Franzens University Graz, 2003, 52 pages.
Multigrid methods for the solution of optimal control optimality systems are
discussed. These problems arise in the optimal control of systems governed by
partial differential equations of elliptic, parabolic, and hyperbolic type.
Editor's Note: See http://www.kfunigraz.ac.at/imawww/borzi/publist.html.
-------------------------------------------------------
Date: Fri, 13 May 2005 15:37:41 +0200
From: Gundolf Haase
Subject: An Interesting AMG Concept
Algebraic multigrid based on computational molecules,
1: Scalar elliptic problems, RICAM Report, 2005, 22 pages, 4 figures.
J.K. Kraus and J. Schicho
RICAM Institute, Linz, Austria
We consider the problem of splitting a symmetric positive definite (SPD)
stiffness matrix A arising from finite element discretization into the sum of
edge matrices thereby assuming that A is given as the sum of symmetric
positive semidefinite (SPSD) element matrices. We give necessary and
sufficient conditions for the existence of a splitting into SPSD edge matrices
and provide a feasible algorithm for their computation.
Based on this disassembling process we present a new concept of âstrongâ and
âweakâ connections (edges), which provides a basis for selecting the
coarse-grid nodes in algebraic multigrid methods. Furthermore, we examine the
utilization of computational molecules (small collections of edge matrices)
for deriving interpolation rules. The reproduction of edge matrices on coarse
levels offers the opportunity to combine classical coarsening algorithms with
effective (energy minimizing) interpolation principles yielding a flexible and
robust new variant of AMG.
AMS Subject Classification: 65F10, 65N20, 65N30
Key words: edge matrices, algebraic multigrid, interpolation weights, coarse-
grid selection
Editor's Note: See http://www.ricam.oeaw.ac.at/people/page.cgi?firstn=Johannes;lastn=Kraus.
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End of MGNet Digest
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