Publications by Allan Svejstrup Nielsen

A Minimally Intrusive Low-Memory Approach to Resilience for Existing Transient Solvers

We propose a novel, minimally intrusive approach to adding fault tolerance to existing complex scientific simulation codes, used for addressing a broad range of time-dependent problems on the next generation of supercomputers. Exascale systems have the pot ...

2019

Validation of the ICRF antenna coupling code RAPLICASOL against TOPICA and experiments

Olivier Sauter, Basil Duval, Stefano Coda, Timothy Goodman, Yves Martin, Jean-Marc Moret, Duccio Testa, Patrick Blanchard, Bruno Marchand, Holger Reimerdes

In this paper we validate the finite element code RAPLICASOL, which models radiofrequency wave propagation in edge plasmas near ICRF antennas, against calculations with the TOPICA code. We compare the output of both codes for the ASDEX Upgrade 2-strap ante ...

IOP Publishing Ltd2019

Scaling and Resilience in Numerical Algorithms for Exascale Computing

Allan Svejstrup Nielsen

The first Petascale supercomputer, the IBM Roadrunner, went online in 2008. Ten years later, the community is now looking ahead to a new generation of Exascale machines. During the decade that has passed, several hundred Petascale capable machines have bee ...

EPFL2018

Communication-aware adaptive parareal with application to a nonlinear hyperbolic system of partial dierential equations

Jan Sickmann Hesthaven, Allan Svejstrup Nielsen, Gilles Brunner

In the strong scaling limit, the performance of conventional spatial domain decomposition techniques for the parallel solution of PDEs saturates. When sub-domains become small, halo-communication and other overheard come to dominate. A potential path beyon ...

2017

Fault Tolerance in the Parareal Method

Jan Sickmann Hesthaven, Allan Svejstrup Nielsen

Parallel-in-time integration is an often advocated approach for extracting parallelism in the solution of PDEs beyond what is possible using spacial domain decomposition tech- niques. Due to the comparatively low parallel efficiency of parallel-in-time int ...

Assoc Computing Machinery2016

An Adjoint Approach for Stabilizing the Parareal Method

Jan Sickmann Hesthaven, Allan Svejstrup Nielsen, Yvon Maday

The parareal algorithm seeks to extract parallelism in the time-integration direction of time-dependent differential equations. While it has been applied with success to a wide range of problems, it suffers from some stability issues when applied to non-di ...

2015