DSSC seminar: Prof. dr. Simon Portegies Zwart (Leiden University) and Dr. Michael Wilkinson (University of Groningen)
| When: | Tu 03-05-2016 16:00 - 18:00 |
| Where: | 5161.0105 (Bernoulliborg) |
Video: https://streaming3.service.rug.nl/p2gplayer/Player.aspx?id=cnpFbY
Speaker: Prof. dr. Simon Portegies Zwart
Title: High-performance multi-scale simulations with the Astrophysics Multipurpose Software Environment
Abstract:
I will introduce a general-purpose framework for interconnecting scientific simulation programs using a homogeneous, unified interface. Our framework is intrinsically parallel, and conveniently separates all component numerical modules in memory. This strict separation allows automatic unit conversion, distributed execution of modules on different cores within a cluster or grid, and orderly recovery from errors. The framework can be efficiently implemented and incurs an acceptable overhead. In practice, we measure the time spent in the framework to be less than 1% of the wall-clock time. Due to the unified structure of the interface, incorporating multiple modules addressing the same physics in different ways is relatively straightforward. Different modules may be advanced serially or in parallel. Despite initial concerns, we have encountered relatively few problems with this strict separation between modules, and the results of our simulations are consistent with earlier results using more traditional monolithic approaches. This framework provides a platform for combining existing simulation codes or develop new physical solver codes within a rich "ecosystem" of interchangeable modules.
Biography:
Simon Portegies Zwart is a professor of computational astrophysics at the Sterrewacht Leiden in the Netherlands. His principal scientific interests are high-performance computational astrophysics. This includes parallel algorithms and numerical integration techniques, but also multi-scale and multi-physics modelling, the evolution of hierarchical stellar and planetary systems, and the ecology of dense star clusters. He is editor in chief of the open access journal "Computational Astrophysics and Cosmology" and visiting researcher of the Particle Simulator Team at RIKEN. In his free time, he brews beer and translates Egyptian hieroglyphs.
Speaker: Dr. Michael Wilkinson (University of Groningen)
Title: Big Images + Multi-Scale Analysis = Complexity Challenge
Abstract:
All manner of sensors, detectors, and software allow easy, and even routine acquisition of very large images and volumes, in the order of many gigapixels to well into the terapixel range. These might be stitched images in (ultra)microscopy, showing cm-scale samples at sub-micron or even nanometre resolution, remote sensing images of whole countries at 30-cm resolution for disaster relief, or the results of astronomical surveys, to name but a few. In this talk I will argue that the only real justification for acquisition of such images and volumes, is to use them for multi-scale analysis. This presents us with several challenges, in terms of memory and time complexity of the algorithms used. Several existing solutions using pyramids and tree structures will be reviewed, and some avenues for new research explored. Despite the challenges facing implementation of several techniques, they hold the promise of extracting information on multi-scale physical processes from the data.
Biography:
Michael Wilkinson obtained an MSc in astronomy from the Kapteyn Institute, University of Groningen, after which he worked on image analysis of intestinal bacteria at the Department of Medical Microbiology, University of Groningen, obtaining a PhD at the Institute of Mathematics and Computing Science, in 1995. In 1999 he was appointed Lecturer, at the JBI. In 2009 he became senior lecturer at the JBI, working on morphological image analysis and especially connected morphology. He has organized and taught many courses and tutorials on connected filters, both nationally and internationally, and has authored many papers on the subject, including two invited review papers. He is senior member of the IEEE and member of the IAPR, serving as treasurer of the Dutch section for six years from 2005 until 2011. He is member of the steering committee of the International Symposium for Mathematical Morphology. His current work is on theory and applications of connected and hyperconnected filters, multi-scale analysis, parallel algorithms, and processing large image and volume data sets.