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norskArtikler, rapporter og annet (elektroteknologi): Nye registreringer
Viser treff 61-80 av 118
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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 ... -
Reactive-Based Position Control of an Underactuated Quadrotor
(Chapter; Bokkapittel, 2020-07-20)This paper addresses the problem of position control or waypoint tracking for an underactuated quadrotor. The proposed control law is what is known as reaction based in the way that the attitude system reacts to errors in the translational motion. This methodology requires no generation of desired attitude or angular velocity and the resulting control law is model-independent in that it does ... -
First-year engineering students’ mathematics task performance and its relation to their motivational values and views about mathematics
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-11-26)This study investigates Finnish, Norwegian, and Swedish first-year engineering students’ task performance in mathematics and examines how it relates to their motivational values and beliefs about the nature of mathematics. In a set of seven mathematical tasks, female students outperformed male students, for example, in the simplification of symbolic expressions. Our findings also show that ... -
Perspectives and reflections on teaching linear algebra
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-06-03)This paper presents ‘expert opinions’ on what should be taught in a first-year linear algebra course at university; the aim is to gain a generic picture and general guiding principles for such a course. Drawing on a Delphi method, 14 university professors—called ‘experts’ in this study—addressed the following questions: What should be on a first-year linear algebra undergraduate course for engineering ... -
Coordinated Power Management and Control of Standalone PV-Hybrid System with Modified IWO-Based MPPT
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-09-14)To augment the photovoltaic (PV) power generation conversion, a maximum power point tracking (MPPT) technique plays a very significant role. This article introduces a hybrid MPPT algorithm integrating modified invasive weed optimization (MIWO) and perturb and observe (P&O) technique under the rapid weather change and partial shading scenarios for the efficient extraction of the maximum power from ... -
Themes within lecturers' views on the teaching of linear algebra
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-09-25)This paper reports on themes that arose in an investigation of university lecturers’ views on the teaching of linear algebra. This focus on themes was the initial part of a study concentrating on four areas: What is important to teach in a first course in linear algebra? Are there teaching methods which are particularly suited for such a course? Are there tools that should/should not be used; and ... -
Swedish first-year engineering students’ views of mathematics, self-efficacy and motivation and their effect on task performance
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-08-29)We examine a group (N = 88) of Swedish first-year engineering students, their motivation, self-efficacy, and beliefs about the nature of mathematics, and how these relate to their task performance in mathematics. In our data, engineering students who emphasized the exact reasoning in their view of mathematics performed significantly better in a set of mathematical tasks than those who emphasized ... -
Dual quaternion control: a review of recent results within motion control
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-11-24)This paper presents a review of recent results in the field of dual quaternion based motion control. In addition, we derive two control laws for trajectory tracking control of a fully actuated rigid-body based on the resemblance of dual quaternion kinematics and dynamics to the quaternion based rotational kinematics and dynamics. A velocity error sliding surface and an integrator backstepping ... -
Preliminary Results on Waypoint Tracking for Spacecraft with Actuator Constraints
(Peer reviewed; Chapter; Bokkapittel, 2019-07-22)This paper presents preliminary results on how to perform waypoint tracking with spacecraft with actuator constraints. It considers a simplified spacecraft model and can be considered a deep space model, and shows how to perform waypoint tracking with only one main thruster together with full attitude control. As the spacecraft reaches close to the waypoint during a deceleration phase that makes the ... -
Controlling a Chain of Integrators with Constrained Actuation Using Exponential Activation Functions
(Peer reviewed; Chapter; Bokkapittel, 2019-10-24)This paper shows how to control a chain of integrators with constrained actuation by using exponential activation functions. Specifically, it shows how the control law can be decomposed into several parts that can be activated as they are required, resulting in a simple control law that is able to make the states converge fast to zero. -
Ant colony optimization and analysis of time step resolution in transmission expansion computations for wind power integration
(Chapter; Bokkapittel, 2011)This paper investigates the necessary time step resolution in a transmission expansion planning algorithm based on ant colony optimization. A maximal and efficient wind power integration is the main motivation for the grid expansion, which requires a planning tool dealing with wind energy fluctuations. For the analysis a power system model for the Nordic area is used, including a wind power ...
