Viser treff 121-140 av 217

    • Modeling and Analyzing of Inverters for Controlling Voltage and Frequency in an Islanded Microgrid 

      Khan, Mazhar Ali (Master thesis; Mastergradsoppgave, 2021-05-18)
      Recently, the growth of inverter-based generations (IBGs) like solar photovoltaic (PV) and wind turbine generators in the form of microgrids (MGs) has been increasing. However, control of voltage and frequency becomes a challenging task for MGs especially when they operate in an islanded mode, due to the inherent low-inertia feature of IBGs compared to a grid-tied mode where there is a grid support. ...
    • Tethered Quadcopter Control, Simulation and Modeling platform for a small USV 

      Wæringsaasen, Sindre (Master thesis; Mastergradsoppgave, 2021-05-18)
      Maritime Robotics main intent of the thesis is to develop understanding of a small deployable camera platform capable of providing elevated situational awareness for a small USV using a tether. The thesis goes into the state-ofthe-art methods of usage and control of a tethered drone. The thesis goes into the building and operating of the QAV250 Pixhawk 4 mini drone and making a drone simulation ...
    • Study of Inter Area Oscillations Using Phasor Measurement Units 

      Olsen, Henrik (Master thesis; Mastergradsoppgave, 2021-05-18)
      Low-frequency oscillations in the power system have major repercussions on power system stability and the objective of maximum power transfer. Local and global control strategies have been developed to dampen and impede these oscillations. A modern local control strategy is supplying the automatic voltage regulation (AVR) of the generator with a power system stabilizer (PSS). Modern global control ...
    • A Class-E-Based AC-DC converter for PFC applications 

      Stausland, Kristian (Master thesis; Mastergradsoppgave, 2021-06-22)
      Connection of nonlinear utility load har increased through resent years and is expected to continue increasing. Nonlinear utility load injects harmonic content into the grid and reduces voltage quality for nearby consumers. To limit harmonic content from nonlinear load, the International Electrotechnical Commission requires power supplies to be designed according to IEC 61000-3-2. Fulfilling this ...
    • Solvinkel optimaliserer 

      Nilsen, Bjarne (Master thesis; Mastergradsoppgave, 2021-05-18)
      Snø og andre ting kan reflektere lys på solcellepanelene slik at de produsere mer energi. Refleksjonene kan gjøre slik at den optimale vinkelen til panelene ikke er rett mot solen. Denne rapporten går fort igjennom noen forslag til optimaliseringsalgoritmer for vinklene til solcellepanelene. Videre går den dypere inn på en algoritme som heter «test og sjekk». Kort fortalt går denne algoritmen ...
    • Path planning and reactive based control for a quadrotor with a suspended load 

      Corona Sanchez, Jose Juan; Kristiansen, Raymond; Andersen, Tom Stian (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 

      Al-Sallami, Hussein; Hoff, Bjarte; Østrem, Trond (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 

      Ellingsen, Pål Gunnar; Lorentzen, Dag Arne; Kenward, David; Hecht, James H.; Evans, J. Scott; Sigernes, Fred; Lessard, Marc (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 

      Ho, Tu Dac; Johansen, Tor Arne; Grøtli, Esten Ingar (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 

      Al-Sallami, Hussein; M. Ammar, Ahmed; Nour, Yasser; A. E. Andersen, Michael (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 

      Ekaputri, Januarti Jaya; Fujiyama, Chikako; Chijiwa, Nobuhiro; Ho, Tu Dac; Nguyen, Hung Thanh (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 

      Dreyer, Joshua; Partamies, Noora; Whiter, Daniel; Ellingsen, Pål Gunnar; Baddeley, Lisa; Buchert, Stephan C. (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. 

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

      Andersen, Tom Stian; Kristiansen, Raymond (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 

      Andersen, Tom Stian; Kristiansen, Raymond (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 

      Tossavainen, Timo; Rensaa, Ragnhild Johanne; Haukkanen, Pentti; Mattila, Mika; Johansson, Monica (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 

      Rensaa, Ragnhild Johanne; Hogstad, Ninni Marie; Monaghan, John David (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 

      Pradhan, Chittaranjan; Senapati, Manoj Kumar; Malla, Siva Ganesh; Nayak, Paresh Kumar; Gjengedal, Terje (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 ...
    • Building a Low-Cost Ground Station for Weather Satellite Image Reception 

      Zahid, Ezzatullah (Master thesis; Mastergradsoppgave, 2019-06-27)
      In this Thesis, a small, low-cost, portable and easily deployable ground station was built, to track and receive signals from National Oceanic and Atmospheric Administration (NOAA) weather satellites (series 15, 18 and 19) in VHF and UHF bands, process and convert these to images are presented. A ground station, capable of receiving reasonably good quality images from NOAA weather satellites was ...
    • Application of electric vehicle charging solutions on small maritime vessels 

      Mandasari, Maya (Master thesis; Mastergradsoppgave, 2019-06-28)
      This thesis explores various charging standards for electric vehicles with the goal to find a standard that can be implemented in an electric maritime vessel (EMV). Combined charging system 2.0 (CCS2) is selected and the standard is explained in detail along with the necessary power electronics. Several Matlab and dSPACE simulations is made to test the charging and communication. A laboratory ...