Now showing items 1-20 of 85

    • Additive weighted Lp estimates of some classes of integral operators involving generalized Oinarov kernels 

      Baiarystanov, A.O.; Persson, Lars Erik; Wall, Peter; Abylayeva, A.M. (Journal article; Peer reviewed; Tidsskriftartikkel, 2017)
    • Asymptotic Behaviour of Ground States for Mixtures of Ferromagnetic and Antiferromagnetic Interactions in a Dilute Regime 

      Braides, Andrea; Causin, Andrea; Piatnitski, Andrey; Solci, Margherita (Journal article; Peer reviewed, 2018-04-30)
      We consider randomly distributed mixtures of bonds of ferromagnetic and antiferromagnetic type in a two-dimensional square lattice with probability 1−p 1−p and p, respectively, according to an i.i.d. random variable. We study minimizers of the corresponding nearest-neighbour spin energy on large domains in Z 2 Z2 . We prove that there exists p 0 p0 such that for p≤ p 0 p≤p0 such ...
    • Asymptotics of a spectral-sieve problem 

      Amirat, Youcef; Bodart, Olivier; Chechkin, Gregory; Piatnitski, Andrey (Peer reviewed, 2015-11-18)
      In a bounded domain with a thin periodically punctured interface we study the limit behavior of the bottom of spectrum for a Steklov type spectral problem, the Steklov boundary condition being imposed on the perforation surface. For a certain range of parameters we construct the effective spectral problem and justify the convergence of eigenpairs.
    • Atomized feedback, an approach to automatic formative assessment 

      Steen, Arild; Movik, Hans Richard (Peer reviewed; Chapter, 2017-11)
      In this article, we describe an approach to give automatic formative evaluation by atomizing the feedback. The mechanics in this approach is a large number of multiple-choice tests. The multiplechoice tests are used as voluntary assignments and gives controlled progression by releasing the tests in an order. Instruction is in the spirit of flipped classroom with short video lectures accompanied by ...
    • Blending functions based on trigonometric and polynomial approximations of the Fabius function 

      Olofsen, Hans (Journal article; Tidsskriftartikkel; Peer reviewed, 2019)
      Most simple blending functions are polynomials, while more advanced blending functions are, for example, rational or expo-rational fractions. The Fabius function has the required properties of a blending function, but is a nowhere analytic function and cannot be calculated exactly everywhere on the required domain. We present a new set of trigonometric and polynomial blending functions with the shape ...
    • Boundedness and compactness of a class of Hardy type operators 

      Abylayeva, AAkbota M; Oinarov, Ryskul; Persson, Lars Erik (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-12-13)
      We establish characterizations of both boundedness and of compactness of a general class of fractional integral operators involving the Riemann-Liouville, Hadamard, and Erdelyi-Kober operators. In particular, these results imply new results in the theory of Hardy type inequalities. As applications both new and well-known results are pointed out.
    • Design of water shock tube for testing shell materials 

      Ji, Hongjuan; Mustafa, Mohamad; Khawaja, Hassan Abbas; Ewan, Bruce C.; Moatamedi, Mojtaba (Journal article; Tidsskriftartikkel; Peer reviewed, 2014-04-15)
      This paper presents design considerations for a shock tube experimental rig used to investigate the dynamic failure mechanisms of shell geometries subjected to water shock impact loading. In such setup, it is desirable that the drive pressure used within the tube can provide a wide range of impulsive loads on the test structures and some flexibility can be achieved on the applied pulse durations. ...
    • Dynamic plastic response of beams subjected to localised pulse loads 

      Thil, Nicolas; Mehreganian, Navid; Moatamedi, Mojtaba; Louca, Luke A.; Soleiman Fallah, Arash (Journal article; Peer reviewed, 2018-10-31)
      Localised blast loads give rise to high gradients of overpressure detrimental to structural elements as beams and plates. This article presents an analytical study on the dynamic plastic response of beams made of a ductile metallic material due to close-in pulse pressure loading. The close-in pressure load is characterised by a spatially varying function constant over a central region and exponentially ...
    • Economic evaluation of the Power grid tariff for households With solar Power installed 

      Sæle, Hanne; Bremdal, Bernt Arild (Journal article; Peer reviewed; Tidsskriftartikkel, 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 ...
    • Embeddings of weighted generalized Morrey Spaces into Lebesgue Spaces on fractal sets 

      Samko, Natasha Gabatsuyevna (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-12-19)
      We study embeddings of weighted local and consequently global generalized Morrey spaces defined on a quasi-metric measure set (X, d, μ) of general nature which may be unbounded, into Lebesgue spaces Ls(X), 1 ≤ s ≤ p < ∞. The main motivation for obtaining such an embedding is to have an embedding of non-separable Morrey space into a separable space. In the general setting of quasi-metric measure ...
    • Equivalent integral conditions related to bilinear Hardy-type inequalities 

      Kanjilal, Saikat; Persson, Lars Erik; Shambilova, Guldarya E (Journal article; Tidsskriftartikkel; Peer reviewed, 2019)
      Infinitely many, even scales of, equivalent conditions are derived to characterize the bilinear Hardy-type inequality under various ranges of parameters.
    • Exact Asymptotic Expansion of Singular Solutions for the (2+1)-D Protter Problem 

      Dechevski, Lubomir T (Journal article; Tidsskriftartikkel; Peer reviewed, 2012)
    • Exploring benefits of using blending splines as transition curves 

      Brustad, Tanita Fossli; Dalmo, Rune (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-06-19)
      Track geometry is a fundamental subject in railway construction. With the demand for increased capacity in terms of load and speed, the need for suitable transitions between consecutive track sections is highly relevant. Properly constructed transition curves lead to improved travel comfort, increased safety, and reduced wear. The well known clothoid curve is widely used as a transition curve; ...
    • Exploring future C++ features within a geometric modeling context 

      Bratlie, Jostein; Dalmo, Rune (Peer reviewed; Conference object; Chapter, 2019-11)
      The development of the C++ programming language and its standard library has undergone a renaissance since the introduction of the C++11 standard, making the language more relevant than ever, through modern features, simplification and expansion of the standard library. Comparing past and future feature sets (C++17, C++20, ...) similar to comparing different programming languages. In this article ...
    • Fejér and Hermite-Hadamard Type Inequalities for N-Quasiconvex Functions 

      Abramovich, S; Persson, Lars Erik (Journal article; Peer reviewed; Tidsskriftartikkel, 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.
    • Finite element method application of ERBS triangles 

      Kravetc, Tatiana (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-11)
      In this paper we solve an eigenvalue problem on a circular membrane with fixed outer boundary by using a finite element method, where an element is represented as an expo-rational blending triangle. ERBS triangles combine properties of B-spline finite elements and standard polynomial triangular elements. The overlapping of local triangles allows us to provide a flexible handling of the surface while ...
    • The FlexNett Simulator 

      Bremdal, Bernt Arild; Tangrand, Kristoffer (Journal article; Peer reviewed, 2019)
      This paper documents research conducted in the Norwegian FLEXNETT project.<br>It describes a new tool that was developed to study the future impact of prosumers with PV panels on the grid in Norway and the potential energy flexibility that lies with residential prosumers. Systematic use of energy flexibility can be an important instrument for managing peak loads and voltage problems in weak power ...
    • Fremtidens fleksible distribusjonsnett : fleksibel nettdrift, forbrukerfleksibilitet, plusskunder og forretningsmodeller 

      Sæle, Hanne; Bremdal, Bernt Arild; Tøndel, Inger Anne; Istad, Maren Kristine; Foosnæs, Jan Andor; Nordbø, Per Erik; Kirkeby, Henrik; Høverstad, Boye Annfelt; Mathisen, Geir (Research report; Forskningsrapport, 2016-02-15)
      Denne rapporten er utarbeidet i WP1 og WP2 i prosjektet "Fleksibilitet i fremtidens smarte distribusjonsnett - FlexNett" (2015-2017). FlexNett-prosjektet har som målsetting å bidra til økt fleksibilitet i fremtidens smarte distribusjonsnett gjennom å demonstrere og verifisere tekniske og markedsmessige løsninger for fleksibilitet på ulike nivå i nettet til nytte for ulike aktører. <br> Målsettingen ...
    • Geometric Construction of Some Lehmer Means 

      Høibakk, Ralph; Lukkassen, Dag; Meidell, Annette; Persson, Lars Erik (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-11-14)
      The main aim of this paper is to contribute to the recently initiated research concerning geometric constructions of means, where the variables are appearing as line segments. The present study shows that all Lehmer means of two variables for integer power k and for k = m 2 , where m is an integer, can be geometrically constructed, that Lehmer means for power k = 0,1 and 2 can be geometrically ...
    • Hardy-type inequalities in fractional h-discrete calculus 

      Persson, Lars Erik; Oinarov, Ryskul; Shaimardan, Serikbol (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-04-04)
      The first power weighted version of Hardy’s inequality can be rewritten as [<i>mathematical formula</i>] where the constant <i>C</i> =[<i>p</i> / <i>p</i> - <i><b>a</b></i> - 1]<sup><i>p</i></sup> is sharp. This inequality holds in the reversed direction when<math xmlns="http://www.w3.org/1998/Math/MathML"> <mn>0</mn> <mo>&#x2264;<!-- ≤ --></mo> <mi><i>p</i></mi> <mo>&lt;</mo> <mn>1</mn> ...