• Secondary Network Throughput Optimization of NOMA Cognitive Radio Networks Under Power and Secure Constraints 

      Vo, Van Nhan; Viet Hung, Dang; Tran, Hung; Ha, Dac-Binh; Le, Cong; Ho, Tu Dac; Chakchai, So-In (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-03-31)
      Recently, the combination of cognitive radio networks with the nonorthogonal multiple access (NOMA) approach has emerged as a viable option for not only improving spectrum usage but also supporting large numbers of wireless communication connections. However, cognitive NOMA networks are unstable and vulnerable because multiple devices operate on the same frequency band. To overcome this drawback, ...
    • Security Constrained Unit Commitment and Economic Dispatch applied to the Modified IEEE 39-bus system Case 

      Tricarico, Gioacchino; Azuara-Grande, Luis Santiago; Wagle, Raju; Gonzalez-Longatt, Francisco; Dicorato, Maria; Forte, Giuseppe; Rueda, Jose Luis (Journal article; Tidsskriftartikkel, 2022-12-09)
      The operation schedule of the power generation units in electrical power systems is determined by the optimisation problem known as unit commitment (UC), aiming at minimising the total cost considering the generation constraints. To obtain a feasible solution from the network perspective, the security-constrained UC (SCUC) problem has been defined to embed the network constraints in the optimisation ...
    • Security Constrained Unit Commitment and Economic Dispatch by AC Sensitivity Factors 

      Tricarico, Gioacchino; Wagle, Raju; Azuara-Grande, Luis Santiago; Gonzalez-Longatt, Francisco; Dicorato, Maria; Forte, Giuseppe; Rueda, Jose Luis (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-11-09)
      The dispatch schedule of the electrical power plant units is the result of the solution to the unit commitment optimisation problem, and it minimises the cost of production considering pre-defined technical limits. The security-constrained unit commitment problem has been defined as including the network constraints in the previously mentioned optimisation problem to obtain a feasible power system ...
    • Smart grid solutions for integration of renewable energy in remote communities 

      Hoff, Bjarte (Conference object; Konferansebidrag, 2017)
    • Smarte løsninger for integrering av fornybar energi 

      Hoff, Bjarte (Konferansebidrag; Conference object, 2017)
    • Smarte nett - Framtidas fleksible energisystem 

      Hoff, Bjarte (Conference object; Konferansebidrag, 2016)
    • Smarte nett - Framtidas fleksible energisystem 

      Hoff, Bjarte (Konferansebidrag; Conference object, 2016-03-16)
    • Stabilization of Non-Cooperative Satellites in Low Earth Orbits using Inter-Satellite Atmospheric Drag 

      Oland, Espen; Kristiansen, Raymond (Chapter; Bokkapittel, 2023-08-07)
      This paper presents a novel solution to the problem of stabilization of non-cooperative satellites in low Earth orbits, which utilizes inter-satellite aerodynamic drag effects for generation of aerodynamics moments in the wake of a controlled satellite. Hence, by altering the position of a smaller controlled satellite, we are able to change the wake region and thus provide aerodynamic moments for ...
    • Subsumption architecture applied to flight control using composite rotations 

      Oland, Espen; Andersen, Tom Stian; Kristiansen, Raymond (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 ...
    • Swedish first-year engineering students’ views of mathematics, self-efficacy and motivation and their effect on task performance 

      Tossavainen, Timo; Rensaa, Ragnhild Johanne; Johansson, Monica (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 ...
    • Take-Home Exams in University Mathematics and Science Subjects: Some Ethical Considerations 

      Rensaa, Ragnhild Johanne; Kristiansen, Raymond (Journal article; Tidsskriftartikkel; Peer reviewed, 2024)
      This article addresses some challenging perspectives related to offering take-home exams in mathematics at university level. The challenges arose during work on a previous article where four perspectives originating from Bjerrum Nielsen’s framework (2003) were used to analyze universities’ assessment methods during the Covid lockdown in our country. The perspectives had some ethical considerations ...
    • Themes within lecturers' views on the teaching of linear algebra 

      Rensaa, Ragnhild Johanne; Hogstad, Ninni Marie; Monaghan, John David (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 ...
    • Throughput Optimization for NOMA Energy Harvesting Cognitive Radio with Multi-UAV-Assisted Relaying under Security Constraints 

      Dang, Viet-Hung; Nguyen, Le-Mai-Duyen; Vo, Van Nhan; Tran, Hung; Ho, Tu Dac; Chakchai, So-In; Surasak, Sanguanpong (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-11-28)
      This paper investigates the throughput of a non-orthogonal multiple access (NOMA)-based cognitive radio (CR) system with multiple unmanned aerial vehicle (UAV)-assisted relays under system performance and security constraints. We propose a communication protocol that includes an energy harvesting (EH) phase and multiple communication phases. In the EH phase, the multiple UAV relays (URs) harvest ...
    • Thyristor based short circuit current injection in isolated grids 

      Hoff, Bjarte; Sharma, Pawan; Østrem, Trond (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.
    • TRACKING VOLUME CHANGE OF THE BULK COMMODITIES WITH INTERFEROMETRIC SAR 

      Wu, Zhenming; Ellingsen, Pål Gunnar; Jia, Haiying; Ådland, Roar Os (Journal article; Tidsskriftartikkel; Peer reviewed, 2023)
      Bulk commodities are crucial to global economy and modern society. Some commodities, such as grain, are normally stored in cylindrical tanks. The height of the tank’s roof may be correlated to the substance quantity inside the tank, indicating that roof displacement may be associated with the volume of the bulk commodities. Here we analyzed the displacements derived from C-band Sentinel-1 data ...
    • A Two-Stage Deep Modeling Approach to Articulatory Inversion 

      Sabzi Shahrebabaki, Abdolreza; Olfati, Negar; Imran, Ali Shariq; Johnsen, Magne Hallstein; Siniscalchi, Sabato Marco; Svendsen, Torbjørn Karl (Chapter; Bokkapittel, 2021-05-13)
      This paper proposes a two-stage deep feed-forward neural network (DNN) to tackle the acoustic-to-articulatory inversion (AAI) problem. DNNs are a viable solution for the AAI task, but the temporal continuity of the estimated articulatory values has not been exploited properly when a DNN is employed. In this work, we propose to address the lack of any temporal constraints while enforcing a ...
    • Ubemannede flaksende mikrofly 

      Oland, Espen (Journal article; Tidsskriftartikkel, 2013)
    • Under Seawater Capacitive Power Transfer for Maritime Charging Applications 

      Al-Sallami, Hussein Mahdi Yaseen; Hattori, Reiji; Hoff, Bjarte; Østrem, Trond (Chapter; Bokkapittel, 2023-09-12)
      Underwater capacitive power transfer (CPT) can provide an inexpensive and light electric charging solution with good misalignment tolerance for unmanned maritime vehicles. This paper investigates the effect of the changing of the frequency and the distance on the power transfer and overall efficiency of the underwater CPT system, considering the dielectric losses of the medium. It also proposes and ...
    • Underactuated Control of Quadrotors with Collision Avoidance 

      Oland, Espen; Andersen, Tom Stian; Kristiansen, Raymond (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 ...
    • Underactuated Waypoint Tracking of a Fixed-Wing UAV 

      Oland, Espen; Schlanbusch, Rune; Kristiansen, Raymond (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 ...