Artikler, rapporter og annet (datateknologi og beregningsorienterte ingeniørfag): Nye registreringer

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    • 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 ...

    • Periodic homogenization of nonlocal operators with a convolution-type kernel 

      Piatnitski, Andrey; Zhizhina, Elena (Journal article; Peer reviewed; Tidsskriftartikkel, 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; Tidsskriftartikkel, 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; Tidsskriftartikkel; 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 (Conference object; Konferansebidrag, 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; Tidsskriftartikkel; 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; Tidsskriftartikkel, 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; Tidsskriftartikkel, 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 (Konferansebidrag; Conference object, 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 ...

    • 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)

    • Regression analysis using a blending type spline construction 

      Kravetc, Tatiana; Bang, Børre; Dalmo, Rune (Peer reviewed; Chapter; Bokkapittel, 2017-10-18)
      Regression analysis allows us to track the dynamics of change in measured data and to investigate their properties. A sufficiently good model allows us to predict the behavior of dependent variables with higher accuracy, and to propose a more precise data generation hypothesis. By using polynomial approximation for big data sets with complex dependencies we get piecewise smooth functions. One way ...

    • Recognizing Bedside Events Using Thermal and Ultrasonic Readings 

      Danielsen, Asbjørn; Tørresen, Jim (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-06-09)
      Falls in homes of the elderly, in residential care facilities and in hospitals commonly occur in close proximity to the bed. Most approaches for recognizing falls use cameras, which challenge privacy, or sensor devices attached to the bed or the body to recognize bedside events and bedside falls. We use data collected from a ceiling mounted 80 60 thermal array combined with an ultrasonic sensor ...

    • Lagrangian and ALE Formulations For Soil Structure Coupling with Explosive Detonation 

      Souli, M; Albahkali, E; Shahrour, I; Moatamedi, Mojtaba (Journal article; Tidsskriftartikkel; Peer reviewed, 2017)
      Simulation of Soil-Structure 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 ...

    • Some new Hardy-type inequalities in q-analysis 

      Baiarystanov, A.O.; Persson, Lars Erik; Shaimardan, S.; Temirkhanova, A. (Peer reviewed; Journal article; Tidsskriftsartikkel, 2016-09)
      We derive necessary and sufficient conditions (of Muckenhoupt-Bradley type) for the validity of q -analogs of (r, p) -weighted Hardy-type inequalities for all possible positive values of the parameters r and p . We also point out some possibilities to further develop the theory of Hardy-type inequalities in this new direction.

    • A new discrete Hardy-type inequality with kernels and monotone functions 

      Kalybay, Aigerim; Persson, Lars Erik; Temirkhanova, Ainur (Peer reviewed; Journal article; Tidsskriftartikkel, 2015-10-06)
      A new discrete Hardy-type 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.

    • Some new Hardy-type inequalities for Riemann-Liouville fractional q-integral operator 

      Persson, Lars Erik; Shaimardan, Serikbol (Peer reviewed; Journal article; Tidsskriftsartikkel, 2015-09-24)
      We consider the q-analog of the Riemann-Liouville fractional q-integral operator of order n∈Nn∈N. Some new Hardy-type inequalities for this operator are proved and discussed.

    • Time scale Hardy-type inequalities with ‘broken’ exponent p 

      Oguntuase, James A; Fabelurin, Olanrewaju O; Adeagbo-Sheikh, Abdulaziz G; Persson, Lars Erik (Peer reviewed; Journal article; Tidsskriftsartikkel, 2015-01-16)
      In this paper, some new Hardy-type inequalities involving ?broken? exponents are derived on arbitrary time scales. Our approach uses both convexity and superquadracity arguments, and the results obtained generalize, complement and provide refinements of some known results in literature

    • Asymptotics of a spectral-sieve problem 

      Amirat, Youcef; Bodart, Olivier; Chechkin, Gregory; Piatnitski, Andrey (Peer reviewed; Journal article; Tidsskriftsartikkel, 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.

    • Osmosis for non-electrolyte solvents in permeable periodic porous media 

      Heintz, Alexei; Piatnitski, Andrey (Peer reviewed; Journal article; Tidsskriftsartikkel, 2016-08)
      The paper gives a rigorous description, based on mathematical homogenization theory, for flows of solvents with not charged solute particles under osmotic pressure for periodic porous media permeable for solute particles. The effective Darcy type equations for the flow under osmotic pressure distributed within the porous media are derived. The effective Darcy law contains an additional flux term ...

    • Singularly perturbed spectral problems with Neumann boundary conditions 

      Piatnitski, Andrey; Rybalko, A; Rybalko, V (Peer reviewed; Journal article; Tidsskriftsartikkel, 2015-09-07)
      The paper deals with the Neumann spectral problem for a singularly perturbed second-order elliptic operator with bounded lower order terms. The main goal is to provide a refined description of the limit behaviour of the principal eigenvalue and eigenfunction. Using the logarithmic transformation, we reduce the studied problem to an additive eigenvalue problem for a singularly perturbed Hamilton–Jacobi ...