Recent additions

  • A note on contributions concerning nonseparable spaces with respect to signal processing within Bayesian frameworks 

    Samko, Natasha Gabatsuyevna; Singh, Harpal (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-07-17)
    In this paper, we discuss the study of some signal processing problems within Bayesian frameworks and semigroups theory, in the case where the Banach space under consideration may be nonseparable. For applications, the suggested approach may be of interest in situations where approximation in the norm of the space is not possible. We describe the idea for the case of the abstract Cauchy problem ...
  • Refinements of some classical inequalities via superquadraticity 

    Nikolova, Ludmila; Persson, Lars-Erik; Varošanec, Sanja; Yimer, Markos Fisseha (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-06-21)
    Some new refined versions of the Jensen, Minkowski, and Hardy inequalities are stated and proved. In particular, these results both generalize and unify several results of this type. Some results are also new for the classical situation.
  • A Feedforward Neural Network for Modeling of Average Pressure Frequency Response 

    Pettersson, Klas; Karzhou, Andrei; Pettersson, Irina (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-02-22)
    The Helmholtz equation has been used for modeling the sound pressure field under a harmonic load. Computing harmonic sound pressure fields by means of solving Helmholtz equation can quickly become unfeasible if one wants to study many different geometries for ranges of frequencies. We propose a machine learning approach, namely a feedforward dense neural network, for computing the average sound ...
  • Synaptus: A Matlab/Octave toolbox for synthetic aperture ultrasound imaging. 

    Skjelvareid, Martin (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-08-08)
    Underlying patterns and factors behind suicides of patients in treatment are still unclear and there is a pressing need for more studies to address this knowledge gap. We analysed 278 cases of suicide reported to The Norwegian System of Patient Injury Compensation, drawing on anonymised data, i.e., age group, gender, diagnostic category, type of treatment provided, inpatient vs. outpatient status, ...
  • Continuous refinements of some Jensen-type inequalities via strong convexity with applications 

    Nikolova, Ludmila; Persson, Lars-Erik; Varošanec, Sanja (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-05-23)
    In this paper we prove new continuous refinements of some Jensen type inequalities in both direct and reversed forms. As applications we also derive some continuous refinements of Hermite–Hadamard, Hölder, and Popoviciu type inequalities. As particular cases we point out the corresponding results for sums and integrals showing that our results contain both several well-known but also some new ...
  • Weighted Hardy Operators in Complementary Morrey Spaces 

    Lukkassen, Dag; Persson, Lars-Erik; Samko, Stefan (Journal article; Tidsskriftartikkel; Peer reviewed, 2012-11-11)
    We study the weighted -boundedness of the multidimensional weighted Hardy-type operators and with radial type weight , in the generalized complementary Morrey spaces defined by an almost increasing function . We prove a theorem which provides conditions, in terms of some integral inequalities imposed on and , for such a boundedness. These conditions are sufficient in the general case, but we ...
  • Some new iterated Hardy-type inequalities: the case theta=1 

    Gogatishvili, Amiran; Mustafayev, Rza; Persson, Lars Erik (Journal article; Tidsskriftartikkel; Peer reviewed, 2013-11-08)
    In this paper we characterize the validity of the Hardy-type inequality &#8741 &#8741 &#8747 <sub>s</sub>&#8734) h(z)dz &#8741 p,u,(0,t) &#8741 q,w,(=,&#8734≤ c&#8741h&#8741 1,v(0,&#8734) where 0 < p < ∞,0< q ≤ +∞, u, w and v are weight functions on (0,∞). It is pointed out that this characterization can be used to obtain new characterizations for the boundedness between weighted Lebesgue spaces ...
  • Homogenization of a singular random one-dimensional PDE with time-varying coefficients 

    Pardoux, Etienne; Piatnitski, Andrey (Journal article; Tidsskriftartikkel; Peer reviewed, 2012-05-04)
    In this paper we study the homogenization of a nonautonomous parabolic equation with a large random rapidly oscillating potential in the case of one-dimensional spatial variable. We show that if the potential is a statistically homogeneous rapidly oscillating function of both temporal and spatial variables, then, under proper mixing assumptions, the limit equation is deterministic, and convergence ...
  • Isogeometric analysis using a tensor product blending spline construction 

    Kravetc, Tatiana (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-06-01)
    In this paper, we introduce a blending spline type construction into the isogeometric analysis. We consider a general algorithm for solving a number of boundary value problems, including heat equation, wave equation, linear elasticity, etc. The usage of blending spline construction in the isogeometric context mixes standard finite element and NURBS-based approaches while accumulating the benefits ...
  • Experiments on turbulence from colliding ice floes 

    Løken, Trygve Kvåle; Marchenko, Aleksey; Ellevold, Thea Josefine; Rabault, Jean; Jensen, Atle (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-06-16)
    Increased knowledge about energy dissipation processes around colliding ice floes is important for improved understanding of atmosphere-ice-ocean energy transfer, wave propagation through sea ice, and the polar climates. The aim of this study is to obtain such information by investigating colliding ice floe dynamics in a large-scale experiment and directly measuring and quantifying the turbulent ...
  • Weighted Boundedness of Certain Sublinear Operators in Generalized Morrey Spaces on Quasi-Metric Measure Spaces Under the Growth Condition 

    Samko, Natasha Gabatsuyevna (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-03-17)
    We prove weighted boundedness of Calderón–Zygmund and maximal singular operators in generalized Morrey spaces on quasi-metric measure spaces, in general non-homogeneous, only under the growth condition on the measure, for a certain class of weights. Weights and characteristic of the spaces are independent of each other. Weighted boundedness of the maximal operator is also proved in the case when ...
  • Deployment of a Neo-Hookean membrane: experimental and numerical analysis 

    Moatamedi, Mojtaba; Al-Bahkali, Essam; Erchiqui, Fouad; Souli, M (Journal article; Tidsskriftartikkel; Peer reviewed, 2013-03-31)
    The aim of this research is to assess the response of a thin membrane subjected to high-pressure gas loading for inflation. This procedure is applied during the design process of the membrane structure to allow the product to resist high-pressure loading and to further characterize the hyper-elastic material. The simulation in this work considers the standard procedures used in the LS-DYNA software, ...
  • Fluid-structure Interaction for Water Hammers Effects in Petroleum and Nuclear Plants 

    Messahel, Ramzi; Cohen, B; Souli, M; Moatamedi, Mojtaba (Journal article; Tidsskriftartikkel; Peer reviewed, 2011-12-31)
    Fluid-Structure Interaction (FSI) becomes more and more the focus of computational engineering in Petroleum and Nuclear Industry in the last years. These problems are computer time consuming and require new stable and accurate coupling algorithms to be solved. For the last decades, the new development of coupling algorithms, and the increasing of computer performance have allowed to solve some ...
  • Numerical investigation of vibration and dynamic pressure of a vertical axis wind turbine 

    Erchiqui, Fouad; Souli, M; Moatamedi, Mojtaba; Albahkali, E (Journal article; Tidsskriftartikkel; Peer reviewed, 2014-12-31)
    In the environmental field, the problems of vibration reduction have become a major preoccupation, particularly on the noise generated by the acoustic radiation pressure produced by wind turbines. This paper is aimed at presenting the investigation on the application of FEM element method for study the acoustic radiation pressure produced by vertical-axis wind turbine. For this initiative, we ...
  • On a New Class of Hardy-type Inequalities 

    Adeleke, EO; Cizmesija, Aleksandra; Oguntuase, JA; Persson, Lars Erik; Pokaz, D (Journal article; Tidsskriftartikkel; Peer reviewed, 2012-11-05)
    In this paper, we generalize a Hardy-type inequality to the class of arbitrary non-negative functions bounded from below and above with a convex function multiplied with positive real constants. This enables us to obtain new generalizations of the classical integral Hardy, Hardy-Hilbert, Hardy-Littlewood-Pólya, and Pólya-Knopp inequalities as well as of Godunova’s and of some recently obtained ...
  • A note on the best constants in some hardy inequalities 

    Persson, Lars Erik; Samko, Stefan (Journal article; Tidsskriftartikkel; Peer reviewed, 2015)
    Abstract. The sharp constants in Hardy type inequalities are known only in a few cases. In this paper we discuss some situations when such sharp constants are known, but also some new sharp constants are derived both in one-dimensional and multi-dimensional cases.
  • Rearrangements and jensen type inequalities related to convexity, superquadracity, strong convexity and 1-quasiconvexity 

    Abramovich, Shoshana; Persson, Lars Erik (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-09)
    In this paper we derive and discuss some new theorems related to all rearrangements of a given set in Rn , denoted (x) and use the results to prove some new Jensen type inequalities for convex, superquadratic, strongly convex and 1 -quasiconvex functions.
  • Weighted fractional Hardy operators and their commutators on generalized Morrey spaces over quasi-metric measure spaces 

    Samko, Natasha Gabatsuyevna (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-11-22)
    We study commutators of weighted fractional Hardy-type operators within the frameworks of local generalized Morrey spaces over quasi-metric measure spaces for a certain class of “radial” weights. Quasi-metric measure spaces may include, in particular, sets of fractional dimentsions. We prove theorems on the boundedness of commutators with CMO coefficients of these operators. Given a domain ...
  • Some New Fourier and Jackson–Nikol’skii Type Inequalities in Unbounded Orthonormal Systems 

    Singh, Harpal; Persson, Lars-Erik; Akishev, Gabdolla (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-09-16)
    We consider the generalized Lorentz space L_ψ,q defined via a continuous and concave function ψ and the Fourier series of a function with respect to an unbounded orthonormal system. Some new Fourier and Jackson-Nikol’skii type inequalities in this frame are stated, proved and discussed. In particular, the derived results generalize and unify several well-known results but also some new applications ...
  • On Weighted Fourier InequalitieS –– Some New Scales of Equivalent Conditions 

    Kufner, Alois; Persson, Lars-Erik; Samko, Natasha G. (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-06)
    For Lebesgue spaces on R<sup>n</sup>, we study two-weight p → q-inequalities for Fourier transform. Some sufficient conditions on weights for such inequalities are known for special ranges of parameters p and q. In the same ranges of parameters we show, that in every case each of those conditions can be replaced by infinitely many conditions, even by continuous scales of conditions. We also ...

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