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. ...

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 ...

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 ...

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 ...

En ny teknologi for opptining av fisk gjør det mulig å gjenvinne fersk kvalitet dersom fisken er frosset helt fersk. Det muliggjør overføring av oversjøisk transport av laks og ørret fra fly til skip, noe som kan redusere de norske klimagassutslippene med anslagsvis 800.000 tonn.<p> <p>Tineteknologien er EU­patentert av det norskeide tyske selskapet Coolnova UG. Blodferske fiskeprodukter kan ...

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 ...

Purpose - The aim was to describe magnetic resonance imaging findings in patients planned for lumbar spinal stenosis surgery. Further, to describe possible associations between MRI findings and patient characteristics with patient reported disability or pain.<p> <p>Methods - The NORDSTEN spinal stenosis trial included 437 patients planned for surgical decompression of LSS. The following MRI ...

Selecting the right location for a den during the breeding season is a type of habitat selection in the Arctic fox (Vulpes lagopus) that is likely to affect its reproductive success. A den’s suitability likely depends on its ability to provide shelter, as well as its proximity to prey resources. Depending on the different relative risks that Arctic foxes may face across their broad circumpolar range, ...

In 2018, Russian coast guard vessels fired upon and apprehended three Ukrainian naval vessels and the crew on board near the Kerch Strait off the coast of Crimea. The case was brought before the ITLOS for the prescription of provisional measures and is pending the decision of the Annex VII arbitral tribunal. Since Russia has issued a declaration in accordance with art. 298(1)(b) of the LOSC, excluding ...

Introduction: In spite of adolescents' rights to be involved in decisions that concern their health and life, limited research has been published reporting on their involvement in mental health research. Therefore, we aim to present experiences and reflections based on the involvement of adolescents in mental health research, to describe the collaborative relationship between researchers and ...