Recent additions

  • Asymptotics of fundamental solutions for time fractional equations with convolution kernels 

    Kondratiev, Yuri; Piatnitski, Andrey; Zhizhina, Elena (Journal article; Peer reviewed, 2020-09-11)
    The paper deals with the large time asymptotic of the fundamental solution for a time fractional evolution equation with a convolution type operator. In this equation we use a Caputo time derivative of order α ∈ (0, 1), and assume that the convolution kernel of the spatial operator is symmetric, integrable and shows a super-exponential decay at infinity. Under these assumptions we describe the ...
  • Altering perceptions, visualizing sub-ground metal objects 

    Pedersen, Aleksander (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-06)
    Smart phones and sensor technology represent a key part of everyday life and are being used in areas such as safety, training, healthcare and others. Utilizing an array of internal sensors and a metal detector requires an evaluation of the precision of the measurements and performance reviews. Metal detectors are versatile, with uses in healthcare as well as recreational, but a common issue often ...
  • Finite element application of ERBS extraction 

    Kravetc, Tatiana; Dalmo, Rune (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-04-24)
    In this paper we explore ERBS extraction in application to a heat conduction problem.Two types of basis functions are considered: B-spline and expo-rational B-spline (ERBS)combined with Bernstein polynomials. The first one is a global basis defined on a subdomain whose size is related to the spline degree, while the second one is a strictlylocal basis under the local geometry. While all the coefficients ...
  • Bruk av droner i nordområdene 

    Bakken, Trond; Johnsen, Stig Ole; Holmstrøm, Sture; Merz, Mariann; Transeth, Aksel Andreas; Grøtli, Esten Ingar; Risholm, Petter; Storvold, Rune (Research report; Forskningsrapport, 2020-05-13)
    Formålet med denne rapporten er å vise eksempler på bruk av fjernstyrte og autonome droner i petroleumssektoren og vise hvilke utviklingstrender innen droneteknologi som er viktige. Utfordringer og muligheter for bruk av droner i nordområdene er spesielt vektlagt. Teknologi for og anvendelser av flyvende droner, droner på havoverflaten og droner under vann er behandlet i denne rapporten. Rapporten ...
  • A field study of sensors for winter road assessment 

    Brustad, Tanita Fossli; Pedersen, Aleksander; Bang, Børre (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-09-02)
    Winter road assessment is a research field with considerable progress over the last 10 years. Various sensors and methods have been tested and analysed, often in a laboratory setting, in order to come up with robust and valid assessment tools that can be used to warn the driver, road users in general, and maintenance personnel of critical conditions. In this paper we compare the field measurements ...
  • Local refinement of ERBS curves 

    Dalmo, Rune (Journal article; Peer reviewed; Chapter, 2013-12-31)
    Expo-rational B-splines (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 ...
  • 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; ...
  • A study on hybrid sensor technology in winter road assessment 

    Pedersen, Aleksander; Brustad, Tanita Fossli (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-03-23)
    Road conditions during the winter months in Nordic countries can be highly unstable. Slippery roads combined with heavy haul traffic and ordinary road users can create dangerous, even lethal, situations if road maintenance is unsuccessful. Accidents and critical road conditions may lead to blocked roads, putting strain on a limited number of main roads in many regions, and may in the worst case ...
  • Hardy-type inequalities over balls in R^N for some bilinear and iterated operators 

    Jain, Pankaj; Kanjilal, Saikat; Persson, Lars Erik (Journal article; Tidsskriftartikkel; Peer reviewed, 2019)
    Some new multidimensional Hardy-type inequalites are proved and discussed. The cases with bilinear and iterated operators are considered and some equivalence theorems are proved.
  • Preliminary studies on transition curve geometry: Reality and virtual reality 

    Brustad, Tanita Fossli (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-02-01)
    The topic of transition curves is well known in track and road engineering. Over the years the need for easement between straight and curved sections in railway and road design has grown, with an important reason being increase in vehicle speed. Testing of transitions is often done with graph analysis where the property of lateral change of acceleration is compared between varieties of curves. ...
  • Railway transition curves: A review of the state-of-the-art and future research 

    Brustad, Tanita Fossli; Dalmo, Rune (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-05-18)
    Transition curves are a useful tool for lateral alignment of railway segments. Their design is important to ensure safe and comfortable travel for passengers and cargo. Well designed transition curves can lead to reduced wear of tracks and vehicles, which is beneficial from a maintenance point of view. Extensive studies have been performed through decades to find transition curves that can replace ...
  • SOME NEW REFINEMENTS OF HARDY-TYPE INEQUALITIES 

    Oguntuase, J. A.; Fabelurin, Olanrewaju O; Persson, Lars Erik; Adeleke, EO (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-02-11)
    We obtain some further refinements of Hardy-type inequalities via superqudraticity technique. Our results both unify and further generalize several results on refinements of Hardy-type inequalities in the literature.
  • Some inequalities related to strong convergence of Riesz logarithmic means 

    Lukkassen, Dag; Persson, Lars Erik; Tephnadze, George; Tutberidze, Giorgi (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-03-23)
    In this paper we derive a new strong convergence theorem of Riesz logarithmic means of the one-dimensional Vilenkin–Fourier (Walsh–Fourier) series. The corresponding inequality is pointed out and it is also proved that the inequality is in a sense sharp, at least for the case with Walsh–Fourier series.
  • Some new Fourier inequalities for unbounded orthogonal systems in Lorentz-Zygmund spaces 

    Akishev, Gabdolla; Lukkassen, Dag; Persson, Lars Erik (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-03-20)
    In this paper we prove some essential complements of the paper (J. Inequal. Appl. 2019:171, 2019) on the same theme. We prove some new Fourier inequalities in the case of the Lorentz–Zygmund function spaces L q,r (logL ) α Lq,r(log⁡L)α involved and in the case with an unbounded orthonormal system. More exactly, in this paper we prove and discuss some new Fourier inequalities of this type for ...
  • Recent trends in operation modal analysis techniques and its application on a steel truss bridge 

    Singh, Harpal; Grip, Niklas (Journal article; Tidsskriftartikkel; Peer reviewed, 2019)
    Aging of infrastructure causes many problems with great consequences, essentially economical. Operation modal analysis (OMA) is one of the most crucial techniques used for dynamic analysis of civil engineering structures (e.g. bridges, dams or tunnels). OMA uses various time and frequency domain methods to obtain the modal parameters. The analysis of OMA techniques can be used to detect, locate and ...
  • 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.
  • Singularly perturbed spectral problems in a thin cylinder with fourier conditions on its bases 

    Piatnitski, Andrey; Rybalko, Volodymyr (Journal article; Tidsskriftartikkel; Peer reviewed, 2019)
    The paper deals with the bottom of the spectrum of a singularly perturbed second order elliptic operator defined in a thin cylinder and having locally periodic coefficients in the longitudinal direction. We impose a homogeneous Neumann boundary condition on the lateral surface of the cylinder and a generic homogeneous Fourier condition at its bases. We then show that the asymptotic behavior of the ...
  • Homogenization of Levy-type operators with oscillating coefficients 

    Kassmann, Moritz; Piatnitski, Andrey; Zhizhina, Elena (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-01-05)
    The paper deals with homogenization of Lévy-type operators with rapidly oscillating coefficients. We consider cases of periodic and random statistically homogeneous micro-structures and show that in the limit we obtain a Lévy-operator. In the periodic case we study both symmetric and non-symmetric kernels whereas in the random case we only investigate symmetric kernels. We also address a nonlinear ...
  • Homogenization of biased convolution type operators 

    Piatnitski, Andrey; Zhizhina, Elena (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-11-07)
    This paper deals with homogenization of parabolic problems for integral convolution type operators with a non-symmetric 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 ...
  • 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 ...

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