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• Norwegian freshmen engineering students' self-efficacy, motivation, and view of mathematics in light of task performance ﻿

(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-02-15)
We report on 71 Norwegian freshmen engineering students' self-efficacy and motivation in mathematics. Students' responses to five-point Likert scales were analysed across three groups corresponding to different performance levels on a set of mathematical tasks. The groups were investigated to trace differences in self-efficacy, motivation, and the epistemological beliefs about the nature of mathematics. ...
• Control of Spacecraft Formation with Disturbance Rejection and Exponential Gains ﻿

(Journal article; Tidsskriftartikkel; Peer reviewed, 2013)
We address the problem of state feedback translational motion control of a spacecraft formation through a modified sliding surface controller using variable gains and I^2 action for disturbance rejection. The exponential varying gains ensure faster convergence of the state trajectories during attitude maneuver while keeping the gains small (and the system less stiff) for station keeping. Integral ...
• Ingeniørstudenters bruk av læringsverktøy i et lineær algebraemne : hvilken rolle spiller nettbaserte forelesninger? ﻿

(Journal article; Tidsskriftartikkel; Peer reviewed, 2015-11-11)
I denne artikkelen diskuteres studentenes bruk av læringsverktøy med spesielt fokus på et nettbasert tilbud. Egne forelesninger i et emne i lineær algebra for master ingeniørstudenter, fjerde år, har blitt streamet og publisert, og jeg har undersøkt hvordan studentene har brukt disse forelesningene. Data er innsamlet første og tredje gang dette ble gjort, og hovedvekten i denne artikkelen er lagt ...
• A note about frequencies being close or amplitudes being small in frequency analysis ﻿

(Journal article; Tidsskriftartikkel; Peer reviewed, 2015-10-10)
In an earlier paper, an alternative method for how to solve the frequency analysis problem was offered. The object of the present paper is to bring about how to handle situations where the frequencies are close to each other or there is an amplitude that is really small.
• En tematisk analyse av hva ingeniørstudenter gjør når de lærer lineær algebra ﻿

(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-09-15)
Denne artikkelen diskuterer hva ingeniørstudenter gjør når de lærer lineær algebra. Arbeidet inngår i et pågående forskningsprosjekt om læring, og grunnlagsdataene for artikkelen ble samlet inn ved at studentene besvarte et obligatorisk spørreskjema der spørsmålet om hva de gjør når de lærer lineær algebra, ble stilt som et åpent spørsmål. Dataene representerer derfor studentenes egne ord om hva de ...
• A computational intelligence-based maximum power point tracking for photovoltaic power generation system with small‐signal analysis ﻿

(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-10-01)
There are multiple peak functions in its output power characteristic curve of a photovoltaic (PV) array under partial shading conditions (PSCs), the perturb and observe (P&O) may fail to track the global maximum power point (GMPP). Therefore, a reliable maximum power point tracking (MPPT) technique is essential to track the GMPP within an appropriate time. This article proposes a hybrid technique ...
• Bio‐inspired hybrid BFOA‐PSO algorithm‐based reactive power controller in a standalone wind‐diesel power system ﻿

(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-01-05)
With an increase in the penetration of renewable energy sources such as wind into the power systems, the operation and control of voltage/reactive power have become more complicated and challenging than ever. As a result, the reactive power imbalance between reactive power generation and demand instigates a reduction in system voltage stability. To deal with the aforesaid scenarios, automatic voltage ...
• PSO and Kalman Filter-Based Node Motion Prediction for Data Collection from Ocean Wireless Sensors Network with UAV ﻿

(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-05-13)
In this paper, we consider a wireless sensor network of nodes at the sea surface drifting due to wind and sea currents. In our scenario an Unmanned Aerial Vehicle (UAV) will be used to gather data from the sensor nodes. The goal is to find a flyable path which is optimal in terms of sensor node energy consumption, total channel throughput between the UAV and sensor nodes, flight time for the UAV and ...
• Optimal Solutions for Underwater Capacitive Power Transfer ﻿

(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-12-09)
Capacitive power transfer (CPT) has attracted attention for on-road electric vehicles, autonomous underwater vehicles, and electric ships charging applications. High power transfer capability and high efficiency are the main requirements of a CPT system. This paper proposes three possible solutions to achieve maximum efficiency, maximum power, or conjugate-matching. Each solution expresses the ...
• Keeping track of samples in multidisciplinary fieldwork ﻿

(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-11-10)
We here present methods, tools and results for efficiently collecting metadata and tracking samples collected in the field. The samples and metadata were collected during scientific cruises conducted by amongst others marine biologists, oceanographers, geochemists and marine geologists in the Nansen Legacy project. It is here reported on the successful development and implementation of a system ...
• Modified demagnetisation control strategy for low-voltage ride-through enhancement in DFIG-based wind systems ﻿

(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-02-16)
The large-scale wind energy conversion systems (WECSs) based on doubly-fed induction generators (DFIGs) are very popular in recent years due to the numerous technical and economic benefits. With the increasing penetration level of wind energy, the latest grid codes require the DFIG-based WECSs to remain connected to the grid under grid fault scenarios and deliver the required reactive power into ...
• Path planning and reactive based control for a quadrotor with a suspended load ﻿

(Conference object; Konferansebidrag, 2021-06)
This paper presents a solution to quadrotor cargo transportation, more precisely when cargo is suspended as a sling load. The challenge lies in payload position control and swing attenuation, which we approach by dividing the model into subsystems: attitude quadrotor in free flight, and translational and attitude load dynamics. We propose a solution based on reactive control, in the sense that we ...
• Maximum Available Power of Undersea Capacitive Coupling in a Wireless Power Transfer System ﻿

(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-06-23)
This paper studies the maximum available power of a dissipative capacitive power transfer (CPT) system submerged in seawater. The CPT system's maximum power capability is driven using the network theory, precisely the conjugate-image approach. The equations of the maximum available load power and the system's corresponding efficiency are expressed as a function of the capacitive coupling parameters. ...
• Observations of sunlit N2+ aurora at high altitudes during the RENU2 flight ﻿

(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-09-24)
We present measurements of sunlit aurora during the launch of the Rocket Experiment for Neutral Upwelling 2 (RENU2) on the 13 December 2015, 07:34 UTC. The in situ auroral conditions coincide with those of sunlit aurora and were characterised by the 391.4 and 427.8 nm N<sub>2</sub> <sup>+</sup> emissions. A correlation between several auroral wavelengths, as measured by a meridian-scanning ...
• PSO and Kalman Filter-Based Node Motion Prediction for Data Collection from Ocean Wireless Sensors Network with UAV ﻿

(Conference object; Konferansebidrag, 2021-01)
In this paper, we consider a wireless sensor network of nodes at the sea surface drifting due to wind and sea currents. In our scenario an Unmanned Aerial Vehicle (UAV) will be used to gather data from the sensor nodes. The goal is to find a flyable path which is optimal in terms of sensor node energy consumption, total channel throughput between the UAV and sensor nodes, flight time for the ...
• A Class-E-Based Resonant AC-DC Converter With Inherent PFC Capability ﻿

(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-03-22)
This paper investigates the use of the class-E inverter for power factor correction (PFC) applications. Analytical and state-space models are derived showing the class-E inverter’s capability of achieving inherent PFC operation with a constant duty cycle. The inherent PFC operation limits the controller responsibility to the regulation of the output voltage, which is key for resonant converters with ...
• Improving Geopolymer Characteristics with Addition of Poly-Vinyl Alcohol (PVA) Fibers ﻿

(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-04-20)
This paper presents the benefits of PVA fibers in improving the mechanical properties of class F fly-ash-based geopolymer concrete. The activator used in the geopolymer was 8M sodium hydroxide (NaOH) and sodium silicate (Na<sub>2</sub>SiO<sub>3</sub>), with a mass ratio of Na<sub>2</sub>SiO<sub>3</sub> to NaOH varied from 1.5 to 2.5. Cylindrical specimens with a diameter of 100 mm and a height of ...
• Characteristics of fragmented aurora-like emissions (FAEs) observed on Svalbard ﻿

(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-03-04)
This study analyses the observations of a new type of small-scale aurora-like feature, which is further referred to as fragmented aurora-like emission(s) (FAEs). An all-sky camera captured these FAEs on three separate occasions in 2015 and 2017 at the Kjell Henriksen Observatory near the arctic town of Longyearbyen, Svalbard, Norway. A total of 305 FAE candidates were identified. They seem to appear ...
• Electric Ships in Norway - Experiences and Future trends. ﻿

(Conference object; Konferansebidrag, 2020)
• Adaptive Backstepping Control for a Fully-Actuated Rigid-Body in a Dual-Quaternion Framework ﻿

(Chapter; Bokkapittel, 2020-03-12)
We address the trajectory tracking problem for a fully actuated rigid-body with unknown mass and inertia parameters and unknown disturbance forces, using an adaptive backstepping controller based on dual-quaternions. We show that the proposed controller, in closed loop with a nonlinear model of the system, renders the equilibrium points uniformly asymptotically stable. The proposed controller ...