Browsing Institutt for elektroteknologi by Title

Now showing items 112-131 of 191

    • Når blir skipsfarten grønn? 

      Hoff, Bjarte; Østrem, Trond (Kronikk; Chronicle, 2018-04-25)
      n av utfordringene i forbindelse med dagens skipsfart er utslipp til luft, hovedsakelig karbondioksid og nitrogenoksider. Disse utslippene er knyttet til oljefyrte forbrenningsmotorer som dominerer dagens skipsflåte. Det er overveiende sannsynlig at det er en direkte sammenheng mellom global oppvarming og utslipp av klimagasser. Utslipp til luft kan også bidra til sur nedbør og svevestøv, for å nevne ...

    • Non-directional Overcurrent Protection Relay Testing Using Virtual Hardware-in-the-Loop Device 

      Pham, Le Nam Hai; Wagle, Raju; Gonzalez-Longatt, Francisco; Acosta Montalvo, Martha Nohemi (Chapter; Bokkapittel, 2023-05-17)
      Protective relays are an integral part of the power grid, making it reliable and secure against abnormal conditions. Hardware-in-the-Loop (HIL) can be employed to test and validate digital protective relay devices in the real-time simulation comprising hardware and software before actual implementation. However, the HIL technique requires a complex and high-cost technical environment consisting of ...

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

      Rensaa, Ragnhild Johanne; Tossavainen, Timo (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. ...

    • Norwegian, Swedish, and Finnish first-year engineering students' motivational values and beliefs about the nature of mathematics 

      Tossavainen, Timo; Rensaa, Ragnhild Johanne; Haukkanen, Pentti (Chapter; Bokkapittel, 2022)
      We report from a Nordic research project that has investigated first-year engineering students in Norway, Sweden, and Finland, and the relationships between their task performance, motivational values, and beliefs about the nature of mathematics. The present paper focuses on the covariance between their motivational values and beliefs from the perspectives of gender and nationality. The results ...

    • A note about frequencies being close or amplitudes being small in frequency analysis 

      Rensaa, Ragnhild Johanne (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.

    • A Novel Technique to Mitigate the Overlap-Time Effect in Current Source Inverters 

      Sohail, Umer; Østrem, Trond; Hoff, Bjarte (Chapter; Bokkapittel, 2023-08-31)
      Generally, the current source inverter is considered more reliable than the voltage source inverter due to the presence of inductor as an energy storage element on the DC link, but a disruption in the inductor current could significantly risk its reliability. To guarantee the reliable operation of current source inverter, an overlap time must be added to the gate signals of its switches. This ensures ...

    • Ny flåte og elektrifisering – Eksempel på grøne løysingar og utviklinga i dag 

      Hoff, Bjarte (Conference object; Konferansebidrag, 2020)

    • 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 ...

    • Optical water types of the Nordic Seas and adjacent areas 

      Aas, Eyvind; Højerslev, Niels Kristian; Høkedal, Jo; Sørensen, Kai (Journal article; Tidsskriftartikkel; Peer reviewed, 2013-05-20)
      A new map of Jerlov's optical water types in the Nordic Seas and adjacent waters at 139 locations, as well as a table with statistical and geographical properties of the vertical attenuation coefficient of downward irradiance at 475 nm, are presented. The data analysis is based on 715 recordings at different stations, at latitudes between 54° and 82°N, and longitudes between 31°W and 49°E, obtained ...

    • Optimal bruk av reaktive ressurser 

      Arnesen, Jan Tore (Master thesis; Mastergradsoppgave, 2021-05-18)
      God kontroll av reaktiv effekt er en helt nødvendig del av et velfungerende kraftsystem. Reaktiv effekt er funksjon av spenning og lastvinkel, men er i størst grad påvirket av spenningen under normale forhold. Det finnes mange forskjellige reaktive ressurser i kraftsystemet, og de har forskjellige egenskaper og karakteristikker. Statiske reaktive ressurser er kondensatorbatterier, reaktorer og ...

    • Optimal power flow based coordinated reactive and active power control to mitigate voltage violations in smart inverter enriched distribution network 

      Wagle, Raju; Sharma, Pawan; Charu, Sharma; Amin, Mohammad (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-03-30)
      Voltage violations are the main problem faced in distribution networks (DN) with a higher penetration of inverter-based generations (IBG). Active and reactive power control from smart inverters (SI) can mitigate such violations. Optimal power flow (OPF)-based control provides more accurate operating set points for the coordinated operation of SIs. Therefore, this paper presents a three-phase OPF-based ...

    • Optimal routing and charging procedures for electric buses 

      Masliakova, Kseniia (Master thesis; Mastergradsoppgave, 2016-04-06)
      The goal of the project is to use Ant Colony Optimization techniques with Genetic Algorithm to design and analyse routes and recharging schedules for electric buses. One system so-called “en route” charging was analysed where the bus applies a kind of pantograph at bus stops to recharge the bus batteries. This implies more frequent, but short recharging intervals. The program offers diff t variants ...

    • Optimal Solutions for Underwater Capacitive Power Transfer 

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

    • Optimal Volt Var control in Smart Distribution Networks 

      Shamraiz, Shamraiz (Master thesis; Mastergradsoppgave, 2021-05-24)
      Both the generation and transmission power networks are facing new threats and opportunities as the number of distributed energy resources (DERs) grows. Because of the high solar PV penetration, voltage rise and voltage volatility are becoming major problems in the distribution network. Voltage regulating devices (VRDs), such as on load tap changers (OLTCs), phase voltage regulators (SVRs), and ...

    • Optimization of industrial power grid of Narvik 

      Khan, Md Nafis Ul Hoq (Master thesis; Mastergradsoppgave, 2023-05-22)
      The objective of this study is to review a comprehensive plan for optimization framework for the industrial power grid. Few factors considered such as power generation, transmission, distribution, energy storage solutions, cost development. The aim targets an overview of planning and optimization for a hydrogen production plant in Narvik region. It will improve the overall efficiency, stability, ...

    • Optimization of the mass of a sandwich plate that TAM is producing 

      Jensen, Bjarne Steinulv (Master thesis; Mastergradsoppgave, 2017-06-15)
      In this report the possibility to optimize the mass of a sandwich plate that TAM produces have been reviewed. Dimensions of the plate is 2602mm x 2404mm with a core thickness of 40mm, top facing of 3mm and bottom facing of 1mm. To simplify the computations they calculate with uniform facings of 1mm. The function of the sandwich plate is to lift livestock with wires that are fastened in the four ...

    • Parabolic reflector for focusing of underwater acoustic waves 

      Rasmussen, Helene Liebak; Flø, Julianne Tjervåg (Master thesis; Mastergradsoppgave, 2017-06-15)
      Kongsberg Maritime has produced a transponder placed on the seabed designed for receiving and transmitting sound waves from vessels and ROVs. The soundwaves contain data regarding depth and location, and can be transformed to energy thus increasing the transponder battery lifetime. The transponder can only receive a small amount of energy, since its receiving area is small. This project aims to ...

    • 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 ...

    • Path planning for UAV harvesting information from dynamical wireless sensor nodes at sea 

      Ho, Tu Dac; Grøtli, Esten Ingar; Johansen, Tor Arne (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-08-16)
      A system of several wireless sensor nodes and one unmanned aerial vehicle (UAV) is considered in this research. The nodes are only floating and drifting with the sea stream. The UAV will be operating as a data mule to gather sensing information from wireless sensor nodes. Unlike prior studies, this paper addressed a realistic ocean model for the nodes movements which will be the references to the ...

    • Path-following in three dimensions using quaternions for a fixed-wing UAV 

      Andersen, Tom Stian; Kristiansen, Raymond (Conference object; Konferansebidrag, 2017-08-08)
      This paper presents a three dimensional guidance strategy for fixed-wing UAVs using quaternions. The algorithm is based on constructing two quaternions, one which makes the UAV fly towards the path and one that makes the UAV follow the path. These two quaternions are then blended together such that the path-following objective is reached. The guidance algorithm is applied to a simple kinematic model ...