Browsing Artikler, rapporter og annet (datateknologi og beregningsorienterte ingeniørfag) by Title
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Finite element method application of ERBS triangles
(Journal article; Tidsskriftartikkel; Peer reviewed, 201911)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 exporational blending triangle. ERBS triangles combine properties of Bspline 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
(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
(Research report; Forskningsrapport, 20160215)Denne rapporten er utarbeidet i WP1 og WP2 i prosjektet "Fleksibilitet i fremtidens smarte distribusjonsnett  FlexNett" (20152017). FlexNettprosjektet 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
(Journal article; Tidsskriftartikkel; Peer reviewed, 20181114)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 ... 
Hardytype inequalities in fractional hdiscrete calculus
(Journal article; Tidsskriftartikkel; Peer reviewed, 20180404)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>≤<! ≤ ></mo> <mi><i>p</i></mi> <mo><</mo> <mn>1</mn> ... 
Hardytype inequalities over balls in R^N for some bilinear and iterated operators
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019)Some new multidimensional Hardytype inequalites are proved and discussed. The cases with bilinear and iterated operators are considered and some equivalence theorems are proved. 
Homogenization of biased convolution type operators
(Journal article; Tidsskriftartikkel; Peer reviewed, 20191107)This paper deals with homogenization of parabolic problems for integral convolution type operators with a nonsymmetric jump kernel in a periodic elliptic medium. It is shown that the homogenization result holds in moving coordinates. We determine the corresponding effective velocity and prove that the limit operator is a second order parabolic operator with constant coefficients. We also consider ... 
Homogenization of biomechanical models for plant tissues
(Journal article; Tidsskriftartikkel; 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 reactiondiffusionconvection 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 ... 
Homogenization of Levytype operators with oscillating coefficients
(Journal article; Tidsskriftartikkel; Peer reviewed, 20190105)The paper deals with homogenization of Lévytype operators with rapidly oscillating coefficients. We consider cases of periodic and random statistically homogeneous microstructures and show that in the limit we obtain a Lévyoperator. In the periodic case we study both symmetric and nonsymmetric kernels whereas in the random case we only investigate symmetric kernels. We also address a nonlinear ... 
Homogenization of nonisothermal immiscible incompressible twophase flow in porous media
(Journal article; Peer reviewed, 20180315)In this paper, we consider nonisothermal twophase flows through heterogeneous porous media with periodic microstructure. Examples of such models appear in gas migration through engineered and geological barriers for a deep repository for radioactive waste, thermally enhanced oil recovery and geothermal systems. The mathematical model is given by a coupled system of twophase flow equations, and an ... 
Homogenization of random Navier–Stokestype system for electrorheological fluid
(Peer reviewed, 20151119)The paper deals with homogenization of Navier–Stokestype system describing electrorheological fluid with random characteristics. Under nonstandard growth conditions we construct the homogenized model and prove the convergence result. The structure of the limit equations is also studied. 
Lagrangian and ALE Formulations For Soil Structure Coupling with Explosive Detonation
(Journal article; Tidsskriftartikkel; Peer reviewed, 2017)Simulation of SoilStructure Interaction becomes more and more the focus of computational engineering in civil and mechanical engineering, where FEM (Finite element Methods) for soil and structural mechanics and Finite Volume for CFD (Computational Fluid Dynamics) are dominant. New advanced formulations have been developed for FSI (Fluid Structure Interaction) applications using ALE (Arbitrary ... 
Limit behaviour of diffusion in highcontrast periodic media and related Markov semigroups
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019)The goal of the paper is to describe the large time behaviour of a symmetric diffusion in a highcontrast periodic environment and to characterize the limit process under the diffusive scaling. We consider separately the C0 and the L2 settings. 
Local energy markets as a solution for increased energy efficiency and flexibility
(Journal article; Peer reviewed, 2019)With increasing share of distributed renewable energy resources in the grid and arising energy consumer awareness on environmental challenges new market models are sought where energy can be traded in an efficient and enduser centric way. This trend, together with the increasing consciousness on the benefits of local consumption and production has given rise to an increased focus on local energy ... 
Local Flexibility Market Design for Aggregators Providing Multiple Flexibility Services at Distribution Network Level
(Journal article; Tidsskriftartikkel; Peer reviewed, 20180402)This paper presents a general description of local flexibility markets as a marketbased management mechanism for aggregators. The high penetration of distributed energy resources introduces new flexibility services like prosumer or community selfbalancing, congestion management and timeofuse optimization. This work is focused on the flexibility framework to enable multiple participants to compete ... 
Local refinement of ERBS curves
(Journal article; Peer reviewed; Chapter, 20131231)Exporational Bsplines (ERBS) provide a blending type construction where local functions at each knot are blended together by infinitely smooth basis functions. In this work we consider some specific ERBS curves that are approximations of parametric curves. We study local refinement to increase flexibility by inserting local control curves at points of interest on the ERBS curve. Inserting knots ... 
Matrix factorization of multivariate Bernstein polynomials
(Journal article; Tidsskriftartikkel; 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 hypersimplices of respective dimension. The main results in the paper are related to the ... 
Multisource data collection for stateoftheart data analysis from groundproximate images in sea ice classification
(Peer reviewed; Konferansebidrag; Bok; Conference object; Book, 20170808)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 ... 
Multidimensional Hardytype inequalities on time scales with variable exponents
(Journal article; Peer reviewed, 2019)A new Jensen inequality for multivariate superquadratic functions is derived and proved. The derived Jensen inequality is then employed to obtain the general Hardytype integral inequality for superquadratic and subquadratic functions of several variables. 
A new discrete Hardytype inequality with kernels and monotone functions
(Peer reviewed, 20151006)A new discrete Hardytype inequality with kernels and monotone functions is proved for the case 1<q<p<∞1<q<p<∞. This result is discussed in a general framework and some applications related to Hölder’s summation method are pointed out.