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Approaches to learning of linear algebra among engineering students
(Peer reviewed; Bok; Book; Bokkapittel; Chapter, 2017-02)
The present paper investigates engineering students` own descriptions of what they mean by learning of linear algebra and how they know that they have learned something. I seek to extract keywords from engineering students` descriptions of learning of this discipline by drawing on grounded theory techniques and classifying the answers in conceptual and procedural approaches. By this, both detailed ...
Experimental study of relative permittivity of atmospheric ice
(Journal article; Peer reviewed; Tidsskriftartikkel, 2013-01-01)
Atmospheric icing on onshore and offshore structures
is problematic, if we don’t detect and remove it.
Despite of various ice detection techniques, capacitor
based ice sensing technique is interesting one, as it
is based on dielectric properties of material. This technique of measuring icing event is simple and cost-
effective. Based on the dielectric concept, an experi
mental ...
Underactuated Waypoint Tracking of a Fixed-Wing UAV
(Journal article; Peer reviewed; Tidsskriftartikkel, 2013)
In this paper a new method of performing waypoint tracking is shown for underactuated fixed-wing UAVs. The position error can be mapped onto the desired axis using a desired rotation matrix, while the velocity error can be mapped to the desired axis using a desired angular velocity. With all errors defined along one axis, the tracking problem is easily solved using only one thruster. A velocity ...
Underactuated Control of Quadrotors with Collision Avoidance
(Journal article; Peer reviewed; Tidsskriftartikkel, 2013)
In this paper a saturated controller is derived that solves the translational control problem for underactuated quadrotors. The controller is applied to multiple quadrotors during a formation reconfiguration where the quadrotors move from an initial position to a desired position. The null-space-based behavioral control method is a popular method for avoiding collisions between mobile agents, and ...
Real-Time Particle Tracking using a Formation of UAVs
(Journal article; Peer reviewed; Tidsskriftartikkel, 2013)
In this paper the problem of real-time particle tracking is studied. Using sensor measurements, a formation of UAVs autonomously find the closest point with high particle density where they enter a holding pattern. After converging to the holding pattern, one UAV will remain, while the rest will go looking for other maxima. To avoid collisions between the UAVs during the mission, a controller is ...
Estimation of upward radiances and reflectances at the surface of the sea from above-surface measurements
(Journal article; Tidsskriftartikkel; Peer reviewed, 2015-10-02)
During 4 field days in the years 2009–2011, 22 data sets of measurements were collected in the inner Oslofjord, Norway. The data consist of recordings of spectral nadir radiances in air and water as well as spectral downward irradiance in air. The studied wavelengths are 351, 400, 413, 443, 490, 510, 560, 620, 665, 681, 709 and 754 nm.
The water-leaving radiance and the reflected radiance at the ...
A Decoupled Approach for Flight Control
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016)
A decoupling method for flight control is presented that greatly simplifies the controller design. By approximating the higher order derivatives of the angle of attack and sideslip, it enables a rotation controller and a speed controller to be derived independently of each other, and thus gives access to a vast number of controller solutions derived for general classes of rotational and translational ...
Subsumption architecture applied to flight control using composite rotations
(Peer reviewed; Tidsskriftartikkel; Journal article, 2016-03-19)
In this paper the subsumption theory is applied to flight control through composite rotations where multiple tasks can be defined as simple rotations. The tasks can then be arranged as a hierarchy, where the primary task is always fully pursued, and conflicting lower level tasks are removed by the primary rotation. The concept is applied to a group of uavs that move through an urban terrain while ...
Thyristor based short circuit current injection in isolated grids
(Peer reviewed; Bokkapittel; Chapter, 2017-02-16)
This paper proposes a thyristor based short circuit current injector for providing short circuit current in isolated and weak grids, where sufficient fault current to trigger circuit breakers may not be available. This will allow the use of conventional miniature circuit breakers, which requires high fault current for instantaneous tripping. The method has been validated through experiments.
A Reliable Modular Based PV-Battery Hybrid System with Peak Shaving Capability
(Peer reviewed; Chapter, 2018)
The driving factors in emerging photovoltaic (PV) systems and battery-energy-storage systems (BESS) are highly scalable feature, modular and flexible structures with superior transformerless performance. The feasibility of Modular Multilevel Converter (MMC) to operate without overall DC-link allows the integration of PV generators and battery strings with its submodules (SMs), whereas each SM acts ...