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Sigurður Freyr Hafstein - Prófessor

Sigurður Freyr Hafstein

–

Verkfræði- og náttúruvísindasvið

Sigurður Freyr Hafstein

Prófessor

Aðsetur
Tæknigarður / Tg-328
Sími
5254661
Tölvupóstur
shafstein [hjá] hi.is

Starfseining
Raunvísindadeild
Vefsíða
https://notendur.hi.is/~shafstein

ORCID vefsíða
https://orcid.org/0000-0003-0073-2765
Rannsóknagátt – Sigurður Freyr Hafstein

Útgefið efni

2025

MINIMIZATION WITH DIFFERENTIAL INEQUALITY AND EQUALITY CONSTRAINTS APPLIED TO COMPLETE LYAPUNOV FUNCTIONSDiscrete and Continuous Dynamical Systems - Series B

2024

CONTRACTION METRIC COMPUTATION USING NUMERICAL INTEGRATION AND QUADRATUREDiscrete and Continuous Dynamical Systems - Series B
Lyapunov Functions by Interpolating Numerical Quadrature
Convex Lyapunov Functions For Switched Discrete-Time Systems By Linear Programming
Construction of a Contraction Metric for Time-Periodic Systems Using Meshless CollocationIEEE Control Systems Letters
Efficient C++ Implementations of Generalized Interpolation in Reproducing Kernel Hilbert Spaces to Compute Lyapunov Functions
Stability Analysis of Hybrid Integrator-Gain Systems using Linear ProgrammingIFAC-PapersOnLine

2023

PREFACEJournal of Computational Dynamics
Subgradient algorithm for computing contraction metrics for equilibriaJournal of Computational Dynamics
Lyapunov function computation for linear switched systems
Sufficient Stability Conditions for a Class of Switched Systems With Multiple Steady StatesIEEE Control Systems Letters
Linear programming based lower bounds on average dwell-Time via multiple lyapunov functionsEuropean Journal of Control
Triangulations and Error Estimates for Interpolating Lyapunov FunctionsSN Computer Science
Lyapunov Functions for Switched Linear SystemsIEEE Control Systems Letters
REVIEW ON CONTRACTION ANALYSIS AND COMPUTATION OF CONTRACTION METRICSJournal of Computational Dynamics
Positively Invariant Sets for ODEs and Numerical IntegrationProceedings of the International Conference on Informatics in Control, Automation and Robotics
Contraction Metrics by Numerical Integration and QuadratureProceedings of the International Conference on Informatics in Control, Automation and Robotics

2022

WendlandXool: Simplified C Code to Compute Wendland Functions
Sliding Modes and Lyapunov Functions for Differential Inclusions by Linear Programming
Common Lyapunov functions for switched linear systemsIEEE Control Systems Letters
Robustness of Numerically Computed Contraction MetricsSN Computer Science
Statistical Analysis of an Iterative Algorithm Class for Dynamical Systems
EXISTENCE OF COMPLETE LYAPUNOV FUNCTIONS WITH PRESCRIBED ORBITAL DERIVATIVEDiscrete and Continuous Dynamical Systems - Series B
Corrigendum to “Numerical approximation of the data-rate limit for state estimation under communication constraints” [J. Math. Anal. Appl. 473 (2) (2019) 1280–1304] (Journal of Mathematical Analysis and Applications (2019) 473(2) (1280–1304), (S0022247X19300484), (10.1016/j.jmaa.2019.01.022))Journal of Mathematical Analysis and Applications
Eigenpairs for the Analysis of Complete Lyapunov FunctionsComplexity
A Projected Subgradient Method for the Computation of Adapted Metrics for Dynamical SystemsSIAM Journal on Applied Dynamical Systems
Efficient Verification of CPA Lyapunov Functions

2021

Advanced Algorithm for Interpolation with Wendland Functions
Complete lyapunov functions
Computing Contraction MetricsIFAC-PapersOnLine
System specific triangulations for the construction of cpa lyapunov functionsDiscrete and Continuous Dynamical Systems - Series B
Computation and verification of contraction metrics for periodic orbitsJournal of Mathematical Analysis and Applications
Uniformly regular triangulations for parameterizing lyapunov functions
Smooth complete Lyapunov functions for ODEsJournal of Mathematical Analysis and Applications
Computation and verification of contraction metrics for exponentially stable equilibriaJournal of Computational and Applied Mathematics
ResEntSGSoftwareX
Comparison of different radial basis functions in dynamical systems
Robustness of contraction metrics computed by radial basis functions
Computing complete lyapunov functions for discrete-time dynamical systemsDiscrete and Continuous Dynamical Systems - Series B
Minimization With Differential Inequality Constraints Applied To Complete Lyapunov FunctionsMathematics of Computation
A Subgradient Algorithm for Data-Rate Optimization in the Remote State Estimation ProblemSIAM Journal on Applied Dynamical Systems
Computing Contraction Metrics for three-dimensional systemsIFAC-PapersOnLine

2020

Simplicial complex with approximate rotational symmetryJournal of Computational and Applied Mathematics
Automatic determination of connected sublevel sets of CPA lyapunov functionsSIAM Journal on Applied Dynamical Systems
Evaluation of lyapunov function candidates through averaging iterations
CPA lyapunov functions
Iterative Construction of Complete Lyapunov Functions: Analysis of Algorithm Efficiency.
Update (2.0) to LyapXoolSoftwareX

2019

Improved estimation of the chain-recurrent set
Computation of Complete Lyapunov Functions for Three-Dimensional Systems
Numerical analysis project in ODEs for undergraduate students
Complete Lyapunov Functions
LyapXool – a program to compute complete Lyapunov functionsSoftwareX
Clustering algorithm for generalized recurrences using complete Lyapunov functions
Lyapunov functions for linear stochastic differential equations
Fast Algorithms for Computing Continuous Piecewise Affine Lyapunov Functions
Common Lyapunov function computation for discrete-time systems
Numerical approximation of the data-rate limit for state estimation under communication constraintsJournal of Mathematical Analysis and Applications
Computation of the stochastic basin of attraction by rigorous construction of a Lyapunov functionDiscrete and Continuous Dynamical Systems - Series B
Critical tolerance evolution: Classification of the chain-recurrent set.Proceedings of the 15th International Conference on Dynamical Systems: Theory and Applications (DSTA), Volume: Mathematical and Numerical Aspects of Dynamical System Analysis
Efficient computation of Lyapunov functions for nonlinear systems by integrating numerical solutionsNonlinear Dynamics
Algorithm and software to generate code for wendland functions in factorized form
Numerical ode solvers and integration methods in the computation of cpa lyapunov functions
Middle point reduction of the chain-recurrent set

2018

Lyapunov function computation for autonomous linear stochastic differential equations using sum-of-squares programmingDiscrete and Continuous Dynamical Systems - Series B
Iterative construction of complete lyapunov functions
Lyapunov functions for almost sure exponential stability
Verification of a numerical solution to a collocation problem
Probabilistic Basin of Attraction and Its Estimation Using Two Lyapunov FunctionsComplexity
Computational approach for complete Lyapunov functions
Construction of a complete lyapunov function using quadratic programming
Local Lyapunov functions for nonlinear stochastic differential equations by linearization

2017

Study of dynamical systems by fast numerical computation of Lyapunov functionss.Proceedings of the 14th International Conference on Dynamical Systems: Theory and Applications (DSTA)
Analysing dynamical systems towards computing complete lyapunov functions
Wendland functions A C++ code to compute them
Computation of Lyapunov functions for nonautonomous systems on finite time-intervals by linear programmingJournal of Mathematical Analysis and Applications
Efficient algorithms for simplicial complexes used in the computation of lyapunov functions for nonlinear systems
Efficient Lyapunov Function computation for systems with multiple exponentially stable equilibriaProcedia Computer Science

2015

Class library in C++ to compute Lyapunov functions for nonlinear systemsIFAC-PapersOnLine
Computation of local ISS Lyapunov functions with low gains via linear programmingDiscrete and Continuous Dynamical Systems - Series B
Computation of Lyapunov functions for systems with multiple local attractorsDiscrete and Continuous Dynamical Systems- Series A
Computation and verification of lyapunov functionsSIAM Journal on Applied Dynamical Systems
Computing continuous and piecewise affine Lyapunov functions for nonlinear systemsJournal of Computational Dynamics
Lyapunov Function VerificationIFAC-PapersOnLine
Computation of continuous and piecewise affine Lyapunov functions for discrete-time systemsJournal of Difference Equations and Applications
Huge computational methods for Lyapunov functionsDiscrete and Continuous Dynamical Systems - Series B
Review on computational methods for Lyapunov functionsDiscrete and Continuous Dynamical Systems - Series B

2014

Revised CPA method to compute Lyapunov functions for nonlinear systemsJournal of Mathematical Analysis and Applications
Computation of continuous and piecewise affine Lyapunov functions by numerical approximations of the Massera constructionProceedings of the IEEE Conference on Decision and Control
Numerical Computation of Control Lyapunov Functions in the Sense of Generalized Gradients.Proceedings of the 21st International Symposium on Mathematical Theory of Networks and Systems (MTNS)
Computation of Lyapunov functions for discrete-time systems using the Yoshizawa constructionProceedings of the IEEE Conference on Decision and Control
Computation of Local ISS Lyapunov Functions Via Linear Programming.Proceedings of the 21st International Symposium on Mathematical Theory of Networks and Systems (MTNS)
Algorithmic verification of approximations to complete Lyapunov functions.Proceedings of the 21st International Symposium on Mathematical Theory of Networks and Systems (MTNS)
Computation of Lyapunov functions for nonlinear discrete time systems by linear programmingJournal of Difference Equations and Applications
Implementation of a fan-like triangulation for the CPA method to compute Lyapunov functions
Continuous and piecewise affine Lyapunov functions using the Yoshizawa construction

2013

Local Lyapunov Functions for Periodic and Finite-Time ODEs
Construction of a CPA contraction metric for periodic orbits using semidefinite optimizationNonlinear Analysis, Theory, Methods and Applications
Implementation of simplicial complexes for CPA functions in C++11 using the armadillo linear algebra library

2012

Linear programming based Lyapunov function computation for differential inclusionsDiscrete and Continuous Dynamical Systems - Series B
Existence of piecewise linear lyapunov functions in arbitrary dimensionsDiscrete and Continuous Dynamical Systems
Construction of Lyapunov functions for nonlinear planar systems by linear programmingJournal of Mathematical Analysis and Applications

2011

Efficient sampling of saddle points with the minimum-mode following methodSIAM Journal on Scientific Computing

2010

Existence of piecewise affine Lyapunov functions in two dimensionsJournal of Mathematical Analysis and Applications
Computing Lyapunov functions for strongly asymptotically stable differential inclusions

2007

An algorithm for constructing Lyapunov functions.

2006

OLSIM

2005

Modelling of entries and lane-blocks for up-to-date traffic information systems
Simulation of the autobahn traffic in north rhine-westphaliaOperations Research/ Computer Science Interfaces Series
A constructive converse Lyapunov theorem on asymptotic stability for nonlinear autonomous ordinary differential equationsDynamical Systems

2004

OLSIM
Online-Simulation North Rhine-Westphalia - Traffic Information in a Large Scale Freeway Network. 2nd Conference of the Euro-regional Projects (i2tern), Intelligent Infrastructure for the Trans-European Road Network
Future of Traffic Information - Online-Simulation of a Large Scale Freeway Network.IADIS International Conference WWW/Internet 2004, Proceedings Volume 1
Verkehrslage via Internet: autobahn.NRW.Logistics Journal
Lyapunov-föll og reiknirit til smíði þeirra.RAUST - Tímarit um raunvísindi og stærðfræði
A high-resolution cellular automata traffic simulation model with application in a freeway traffic information systemComputer-Aided Civil and Infrastructure Engineering
Traffic forecast in large scale freeway networksInternational Journal of Bifurcation and Chaos in Applied Sciences and Engineering
A constructive converse Lyapunov theorem on exponential stabilityDiscrete and Continuous Dynamical Systems
OLSIM

2003

Cellular Automaton Modeling of the Autobahn Traffic in North Rhine - Westphalia.Proceedings of the 4-th MATHMOD Vienna, 4-th IMCAS Symposium on Mathematical Modelling, ARGESIM Report no. 24
OLSIM - Traffic Forecast and Planning using Simulations.SCS/ASIM - 17. Symposium in Magdeburg, Simulationstechnik
The Traffic State of the Autobahn Network of North Rhine-Westphalia: An Online Traffic Simulation.Proceedings of the 10th World Congress and Exhibition on Intelligent Transport Systems and Services, Solutions for Today... and Tomorrow,

2002

Lyapunov function construction for ordinary differential equations with linear programming.International Journal of Dynamical Systems and Differential Equations
On-Line Simulation and Traffic Forecast: Applications and Results.6th IASTED International Conference, Internet and Multimedia Systems and Applications
Simulation des Autobahnverkehrs in NRW.SCS/ASIM - 16. Symposium in Rostock, Simulationstechnik
Simulation Framework for the Autobahn Traffic in North Rhine-Westphalia.Cellular Automata, proceedings of ACRI 2002, the 5th International
An Online Simulation for the Freeway Network of North Rhine-Westphalia Based on Real-World Traffic Data GI-Technologien für Verkehr und Logistik, IfGI-Prints 13

1999

Control of a Chemical Process by Multi Regional State Space SystemsProceedings of the European Control Conference 1999
Stability of Fuzzy Systems based on an Approximation Argument.Proceedings of EUFIT 1999, AC1-1

1998

Scaling and correlation functions in a model of a two-dimensional earthquake faultPhysica Scripta

1995

Correlation functions and power spectra in a model of an earthquake faultPhysics Letters A

1994

Experimental Investigation of Day-to-Day Route-Choice Behavior and Network Simulations of Autobahn Traffic in North Rhine-Westphalia.

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