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sigurdurhafsteinSigurður Freyr Hafstein, dr. rer. nat.

Professor for applied mathematics
School of Science and Engineering
Menntavegur 1
IS-101 Reykjavik

Telephone: +354 599 6325


Workshop: Algorithms for Dynamical Systems and Lyapunov Functions

At Reykjavik University 17.7-19.7.2013. For more information click on the link on the left.


I have mainly worked on two quite different subjects.

First, I designed and programmed a traffic-simulator that is used to estimate and forecast the traffic-load on the autobahn-network in North Rhine - Westphalia (NRW), which is the most populous German federal-state.  The simulator gets real-time traffic-data every minute from more than 4,000 loop-detectors that are installed on the streets.  This data is used to estimate the traffic- load on the autobahn network (> 12,000 km street-lanes) and to forecast future traffic-loads.  The former minister of transport in NRW, Dr. Axel Horstmann, opened the webpage to the public in September 2002.  There the simulated traffic-load and traffic-forecasts for 30 and 60 minutes, generated by the simulator, are presented.  In 2003 I got the Heinz-Billing Prize of the Max-Planck Institute for my work on this project. 

Second, I have been studying the stability of solutions to ordinary differential equations.  Especially, I designed an algorithm that uses linear programming to generate non-local CPA Lyapunov-functions for uniformly asymptotically stable (UAS) equilibria.  Lyapunov-functions are the generalization of the physical concept "energy" to general ODEs.