Nye registreringer

  • On Some Power Means and Their Geometric Constructions 

    Høibakk, Ralph; Lukkassen, Dag; Meidell, Annette; Persson, Lars Erik (Journal article; Peer reviewed, 2018)
    The main aim of this paper is to further develop the recently initiatedresearch concerning geometric construction of some power means wherethe variables are appearing as line segments. It will be demonstratedthat the arithmetic mean, the harmonic mean and the quadratic meancan be constructed for any number of variables and that all power meanswhere the number of variables are n = 2m, m 1 2 N for all ...
  • Local Flexibility Market Design for Aggregators Providing Multiple Flexibility Services at Distribution Network Level 

    Olivella-Rosell, Pol; Lloret-Gallego, Pau; Munne-Collado, Ingrid; Villafafila-Robles, Roberto; Sumper, Andreas; Ottesen, Stig Ødegaard; Rajasekharan, Jayaprakash; Bremdal, Bernt Arild (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-04-02)
    This paper presents a general description of local flexibility markets as a market-based management mechanism for aggregators. The high penetration of distributed energy resources introduces new flexibility services like prosumer or community self-balancing, congestion management and time-of-use optimization. This work is focused on the flexibility framework to enable multiple participants to compete ...
  • Reliable parameter identification for synchronous machines 

    Alves, Erick Fernando (Master thesis; Mastergradsoppgave, 2018-08-16)
    This work investigates and implements algorithms for reliable parameter identification for salient pole synchronous machines that can be used for condition monitoring, on line assessment of the power grid, and adaptive control. All these applications are steps necessary to enable a smarter power grid, in which seamless integrated digital technology provides state estimation, fault detection, and ...
  • Large-scale Wind Power Integration in Northern Norway 

    Singh, Arwinder (Master thesis; Mastergradsoppgave, 2018-08-16)
    Norway has very high flexibility in energy production since hydropower covers about 95% of yearly energy demand. It is best to have a combination of wind and hydropower and hence it applies perfectly here in Norway. The performance of the wind farm can be significantly enhanced by employing full-capacity converters. The state-of-the-art literature study has been done on Squirrel Cage Induction ...
  • Innvirkninger av distribuert produksjon i svake distribusjonsnett, lokalisert i nordområdene. Hvordan påvirker plusskunder det omkringliggende lavspente distribusjonsnettet. 

    Johannessen, Leif Inge Krogstad (Master thesis; Mastergradsoppgave, 2018-08-16)
    I denne rapporten har virkninger av plusskunder i svake, lavspente distribusjonsnett blitt undersøkt. Gjennom en informasjonsinnsamling, ble de største utfordringer for fremtidige plusskunder identifisert. Herunder aktuelle teknologier, energiresuser, regelverk og tekniske forhold. Det ble undersøkt hvilke utfordringer et nettselskap kan forvente seg, ved introduksjon av lokal produksjon i et ...
  • Rammeverk for modellering og simulering av husholdningsapparater 

    Nilsen, Christian Bjerknes (Master thesis; Mastergradsoppgave, 2018-08-16)
    Denne oppgaven har hatt til hensikt å utarbeide et rammeverk for modellering og simulering av husholdningsapparater i Simulink, hvor det er muligheter for sammenkobling av flere enheter basert på typiske utstyr i norske husholdninger. Tilkoblingen av modellene kan være via TN-nett, IT-nett eller andre mindre kilder i Simulink. Videre er det gjennomført en litteraturstudie av ulike typer utstyr ...
  • Refinements of some limit hardy-Type Inequalities via Superquadracity 

    Oguntuase, James A; Persson, Lars Erik; Fabelurin, Olanrewaju O; Adeagbo-Sheikh, Abdulaziz G (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-11-03)
    Refinements of some limit Hardy-type inequalities are derived and discussed using the concept of superquadracity. We also proved that all three constants appearing in the refined inequalities obtained are sharp. The natural turning point of our refined Hardy inequality is p=2 and for this case we have even equality.
  • Potential type operators in PDEs and their applications 

    Burtseva, Evgeniya; Lundberg, Staffan; Persson, Lars Erik; Samko, Natasha (Journal article; Peer reviewed, 2017-01)
    We prove the boundedness of Potential operator in weighted generalized Morrey space in terms of Matuszewska-Orlicz indices of weights and apply this result to the Hemholtz equation in ℝ3 with a free term in such a space. We also give a short overview of some typical situations when Potential type operators arise when solving PDEs.
  • Some new Two-Sided Inequalities concerning the Fourier Transform 

    Kopezhanova, Aigerim; Nursultanov, Erlan; Persson, Lars Erik (Journal article; Peer reviewed, 2017)
    The classical Hausdorff-Young and Hardy-Littlewood-Stein inequalities do not hold for p > 2. In this paper we prove that if we restrict to net spaces we can even derive a two-sided estimate for all p > 1. In particular, this result generalizes a recent result by Liflyand E. and Tikhonov S. [7] (MR 2464253).
  • Predicting Bedside Falls using Current Context 

    Danielsen, Asbjørn; Bremdal, Bernt Arild (Peer reviewed; Chapter, 2018-02-05)
    Each year about a third of the elderly aged 65 or older experience a fall. Many of these falls could be avoided if fall risk assessment and prevention tools where available in the daily living situation. Such tools would need to use the current context as input to predict an imminent fall. This paper presents an approach predicting imminent falls using data from a roof-mounted infrared array combined ...
  • Fejér and Hermite-Hadamard Type Inequalities for N-Quasiconvex Functions 

    Abramovich, S; Persson, Lars Erik (Journal article; Peer reviewed, 2017-12-28)
    Some new extensions and re finements of Hermite – Hadamard and Fejer type inequalities for functions which are N -quasiconvex are derived and discussed.
  • Economic evaluation of the Power grid tariff for households With solar Power installed 

    Sæle, Hanne; Bremdal, Bernt Arild (Journal article; Peer reviewed, 2017)
    This paper focuses on alternative grid tariffs for household customers with roof top PV-panels ("prosumers"), and evaluates how alternative grid tariffs might affect the benefit from investing in a roof top PV-panel. The paper further shows how different orientations of the PV-panels can affect the benefits for the prosumers subjected to different grid tariffs (for example a power grid tariff), where ...
  • Periodic homogenization of nonlocal operators with a convolution-type kernel 

    Piatnitski, Andrey; Zhizhina, Elena (Journal article; Peer reviewed, 2017)
    The paper deals with a homogenization problem for a nonlocal linear operator with a kernel of convolution type in a medium with a periodic structure. We consider the natural diffusive scaling of this operator and study the limit behavior of the rescaled operators as the scaling parameter tends to 0. More precisely we show that in the topology of resolvent convergence the family of rescaled operators ...
  • Homogenization of biomechanical models for plant tissues 

    Piatnitski, Andrey; Ptashnyk, Mariya (Journal article; Peer reviewed, 2017)
    In this paper homogenization of a mathematical model for plant tissue biomechanics is presented. The microscopic model constitutes a strongly coupled system of reaction-diffusion-convection equations for chemical processes in plant cells, the equations of poroelasticity for elastic deformations of plant cell walls and middle lamella, and Stokes equations for fluid flow inside the cells. The chemical ...
  • Stationary convection-diffusion equation in an infinite cylinder 

    Pettersson, Irina; Piatnitski, Andrey (Journal article; Peer reviewed, 2017-12-21)
    We study the existence and uniqueness of a solution to a linear stationary convection–diffusion equation stated in an infinite cylinder, Neumann boundary condition being imposed on the boundary. We assume that the cylinder is a junction of two semi-infinite cylinders with two different periodic regimes. Depending on the direction of the effective convection in the two semi-infinite cylinders, we ...
  • Pre-evaluation and interactive editing of B-spline and GERBS curves and surfaces 

    Lakså, Arne (Peer reviewed; Conference object; Chapter, 2017-12)
    Interactive computer based geometry editing is very useful for designers and artists. Our goal has been to develop useful tools for geometry editing in a way that increases the ability for creative design. When we interactively editing geometry, we want to see the change happening gradually and smoothly on the screen. Pre-evaluation is a tool for increasing the speed of the graphics when doing ...
  • Two-scale convergence in thin domains with locally periodic rapidly oscillating boundary 

    Pettersson, Irina (Journal article; Peer reviewed, 2017)
    The aim of this paper is to adapt the notion of two-scale convergence in Lp to the case of a measure converging to a singular one. We present a specific case when a thin cylinder with locally periodic rapidly oscillating boundary shrinks to a segment, and the corresponding measure charging the cylinder converges to a one-dimensional Lebegues measure of an interval. Themethod is then applied to the ...
  • A new look at classical inequalities involving Banach lattice norms 

    Nikolova, Ludmila; Persson, Lars Erik; Varosanec, Sanja (Journal article; Peer reviewed, 2017-12-08)
    Some classical inequalities are known also in a more general form of Banach lattice norms and/or in continuous forms (i.e., for ‘continuous’ many functions are involved instead of finite many as in the classical situation). The main aim of this paper is to initiate a more consequent study of classical inequalities in this more general frame. We already here contribute by discussing some results of ...
  • Matrix factorization of multivariate Bernstein polynomials 

    Dalmo, Rune (Journal article; Peer reviewed, 2015)
    Ordinary univariate Bernstein polynomials can be represented in matrix form using factor matrices. In this paper we present the definition and basic properties of such factor matrices extended from the univariate case to the general case of arbitrary number of variables by using barycentric coordinates in the hyper-simplices of respective dimension. The main results in the paper are related to the ...
  • Multi-source data collection for state-of-the-art data analysis from ground-proximate images in sea ice classification 

    Woltmann, Lucas; Dalmo, Rune; Kristiansen, Raymond (Peer reviewed; Conference object; Book, 2017-08-08)
    In modern data analysis it is imperative to use well maintained data sources with curated content. This publication gives an approach for research areas, where there is no such central facility. The specific area used here is sea ice classification from images. The publication is split into two parts. The first part describes the integration of discontinuous sources for different aspects of data ...

Vis mer