U
Ulf Jakob F. Aarsnes
Researcher at Norwegian University of Science and Technology
Publications - 45
Citations - 942
Ulf Jakob F. Aarsnes is an academic researcher from Norwegian University of Science and Technology. The author has contributed to research in topics: Drill string & Backstepping. The author has an hindex of 18, co-authored 43 publications receiving 720 citations. Previous affiliations of Ulf Jakob F. Aarsnes include University of Stavanger.
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Delay-Robust Control Design for Two Heterodirectional Linear Coupled Hyperbolic PDEs
TL;DR: In this article, it was shown that canceling the reflection at the actuated boundary will yield zero delay robustness for systems with strong reflections, and that the corresponding target system should preserve a small amount of this reflection to ensure robustness to a small delay in the loop.
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Linear stability analysis of self-excited vibrations in drilling using an infinite dimensional model
TL;DR: In this paper, a graphical condition for stability based on the Nyquist stability criterion is proposed to predict the occurrence of self-excited vibrations during drilling, which are due to the coupling between the distributed drill string system and the regenerative effect in the bit-rock interaction law.
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An adaptive observer for hyperbolic systems with application to UnderBalanced Drilling
TL;DR: In this article, an adaptive observer design for a first-order hyperbolic system of Partial Differential Equations with uncertain boundary parameters is presented, which relies on boundary measurements only, and is based on a backstepping approach.
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A distributed parameter systems view of control problems in drilling
TL;DR: In this article, a detailed view of estimation and control problems raised by the drilling process where the distributed nature of the system cannot be ignored is given, focusing on the transport phenomena in Managed Pressure Drilling (MPD) and UnderBalanced Operations (UBO).
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Axial and torsional self-excited vibrations of a distributed drill-string
TL;DR: In this article, a distributed axial-torsional drill-string model with a rate-independent bit-rock interaction law is considered to study the occurrence and non-local characteristics of axial and torsional self-excited vibrations as caused by the regenerative effect.