Browsing Artikler, rapporter og annet (datateknologi og beregningsorienterte ingeniørfag) by Title
Now showing items 4564 of 91

On geometric construction of some power means
(Journal article; Peer reviewed, 20181127)In the homogenization theory, there are many examples where the effective conductivities of composite structures are power means of the local conductivities. The main aim of this paper is to initiate research concerning geometric construction of some power means of three or more variables. We contribute by giving methods for the geometric construction of the harmonic mean $ P_{1} $ and the arithmetic ... 
On heat conduction in domains containing noncoaxial cylinders
(Journal article; Tidsskriftartikkel; Peer reviewed, 2012)We consider heat conduction in domains containing noncoaxial cylinders. In particular, we present some regularity results for the solution and consider criteria which ensure the single valueness of the corresponding complex potential. Examples are discussed. In addition, we present some classes of cases where the parameters describing the solution are rational. Alternative ways of calculating the ... 
On Some Power Means and Their Geometric Constructions
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018)The main aim of this paper is to further develop the recently initiatedresearch concerning geometric construction of some power means wherethe variables are appearing as line segments. It will be demonstratedthat the arithmetic mean, the harmonic mean and the quadratic meancan be constructed for any number of variables and that all power meanswhere the number of variables are n = 2m, m 1 2 N for all ... 
Osmosis for nonelectrolyte solvents in permeable periodic porous media
(Peer reviewed, 201608)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 ... 
Periodic homogenization of nonlocal operators with a convolutiontype kernel
(Journal article; Tidsskriftartikkel; Peer reviewed, 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 ... 
Pointwise estimates for heat kernels of convolutiontype operators
(Journal article; Peer reviewed; Tidsskriftartikkel, 20180416)We study the large‐time behaviour of the fundamental solution of parabolic equations with an elliptic part being non‐local convolution‐type operator. We assume that this operator is a generator of a Markov jump process, and that its convolution kernel decays at least exponentially at infinity. The fundamental solution shows rather different asymptotic behaviour depending on whether  x  ≲ t , or t ... 
Potential type operators in PDEs and their applications
(Journal article; Peer reviewed; Tidsskriftartikkel, 201701)We prove the boundedness of Potential operator in weighted generalized Morrey space in terms of MatuszewskaOrlicz indices of weights and apply this result to the Hemholtz equation in ℝ<sup>3</sup> with a free term in such a space. We also give a short overview of some typical situations when Potential type operators arise when solving PDEs. 
Preevaluation and interactive editing of Bspline and GERBS curves and surfaces
(Peer reviewed; Bokkapittel; Konferansebidrag; Conference object; Chapter, 201712)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. Preevaluation is a tool for increasing the speed of the graphics when doing ... 
Predicting Bedside Falls using Current Context
(Peer reviewed; Bokkapittel; Chapter, 20180205)Each year about a third of the elderly aged 65 or older experience a fall. Many of these falls could be avoided if fall risk assessment and prevention tools where available in the daily living situation. Such tools would need to use the current context as input to predict an imminent fall. This paper presents an approach predicting imminent falls using data from a roofmounted infrared array combined ... 
Preliminary studies on transition curve geometry: Reality and virtual reality
(Journal article; Tidsskriftartikkel; Peer reviewed, 20200201)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. ... 
Quantitative analysis of accuracy of voidage computations in CFDDEM Simulations
(Journal article; Tidsskriftartikkel; Peer reviewed, 2012) 
Railway transition curves: A review of the stateoftheart and future research
(Journal article; Tidsskriftartikkel; Peer reviewed, 20200518)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 ... 
Recent trends in operation modal analysis techniques and its application on a steel truss bridge
(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 ... 
Recognizing Bedside Events Using Thermal and Ultrasonic Readings
(Journal article; Tidsskriftartikkel; Peer reviewed, 20170609)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 ... 
Refinements of some limit hardyType Inequalities via Superquadracity
(Journal article; Tidsskriftartikkel; Peer reviewed, 20171103)Refinements of some limit Hardytype inequalities are derived and discussed using the concept of superquadracity. We also proved that all three constants appearing in the refined inequalities obtained are sharp. The natural turning point of our refined Hardy inequality is p=2 and for this case we have even equality. 
Regression analysis using a blending type spline construction
(Peer reviewed; Chapter; Bokkapittel, 20171018)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 ... 
Reiterated homogenization of nonlinear monotone operators in a general deterministic setting
(Journal article; Peer reviewed; Tidsskriftartikkel, 2009)We study reiterated homogenization of a nonlinear nonperiodic elliptic differential operator in a general deterministic setting as opposed to the usual stochastic setting. Our approach proceeds from an appropriate notion of convergence termed reiterated Σconvergence. A general deterministic homogenization theorem is proved and several concrete examples are studied under various structure hypotheses ... 
Rescue of stranded persons. C18. Rescue of stranded passengers in the Arctic
(Forskningsrapport; Chapter, 201812)Since we (the authors) could not be a part of the whole SARex 3 exercise this year, we joined the expedition later than the rest of the participants. We gladly accepted the invitation from the Governor of Svalbard, Kjerstin Askholt, and her staff in Longyearbyen to join their service vessel, MS Polarsyssel, to meet The Norwegian Coast Guard’s vessel, (NOCGV) Svalbard, at the location where the ... 
Resolvent bounds for jump generators
(Journal article; Peer reviewed; Tidsskriftartikkel, 20161202)The paper deals with jump generators with a convolution kernel. Assuming that the kernel decays either exponentially or polynomially, we prove a number of lower and upper bounds for the resolvent of such operators. In particular we focus on sharp estimates of the resolvent kernel for small values of the spectral parameter. We consider two applications of these results. First we obtain pointwise ... 
A sharp boundedness result for restricted maximal operators of VilenkinFourier series on martingale Hardy spaces
(Journal article; Peer reviewed, 20180920)The restricted maximal operators of partial sums with respect to bounded Vilenkin systems are investigated. We derive the maximal subspace of positive numbers, for which this operator is bounded from the Hardy space H p to the Lebesgue space L p for all 0<p≤1 . We also prove that the result is sharp in a particular sense.