Browsing Institutt for matematikk og statistikk by Title
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Abelian equations and rank problems for planar webs
(Journal article; Tidsskriftartikkel; Peer reviewed, 20060504)We find an invariant characterization of planar webs of maximum rank. For 4webs, we prove that a planar 4web is of maximum rank three if and only if it is linearizable and its curvature vanishes. This result leads ... 
Almost complex homogeneous spaces with semisimple isotropy
(Master thesis; Mastergradsoppgave, 201205)We classify the almost complex structures on homogeneous spaces M = G/H of real dimension less than or equal to 6 with semisimple isotropy group H. 
Anomaly of linearization and auxiliary integrals
(Chapter; Bokkapittel, 20071220)In this note we discuss some formal properties of universal linearization operator, relate this to brackets of nonlinear differential operators and discuss application to the calculus of auxiliary integrals, used in ... 
Applying the ICM algorithm for separating pictures consisting of two main parts, background and object application to fMRI recordings and mole pictures
(Master thesis; Mastergradsoppgave, 20090515)This work concentrates on using the ICM algorithm for image restoration. The algorithm has been applied to fMRI recordings and mole pictures 
Automatic nematode detection in cod fillets (Gadus morhua L.) by hyperspectral imaging
(Journal article; Tidsskriftartikkel; Peer reviewed, 2012)Detection of objects embedded in tissue, using visible light, is difficult due to light scattering. The optical properties of the surrounding tissue will influence the spectral characteristics of the light interacting with ... 
Automatic Segmentation of Dermoscopic Images by Iterative Classification
(Journal article; Tidsskriftartikkel; Peer reviewed, 2011)Accurate detection of the borders of skin lesions is a vital first step for computer aided diagnostic systems. This paper presents a novel automatic approach to segmentation of skin lesions that is particularly suitable ... 
Bayesian modeling and significant features exploration in wavelet power spectra
(Journal article; Tidsskriftartikkel; Peer reviewed, 2007) 
Bayesian multiscale analysis of images modeled as Gaussian Markov random fields
(Journal article; Tidsskriftartikkel; Peer reviewed, 2012)A Bayesian multiscale technique for the detection of statistically significant features in noisy images is proposed. The prior is defined as a stationary intrinsic Gaussian Markov random field on a toroidal graph, which ... 
The Capabilities of the EISCAT Svalbard Radar for Interhemispheric Coordinated Studies
(Journal article; Tidsskriftartikkel; Peer reviewed, 2002)In this article we want to present the EISCAT Svalbard Radar (ESR) in some detail, as well as some of the instruments of interest for ionospheric and magnetospheric research that are located in the vicinity of it. We ... 
The categorical theory of relations and quantization
(Working paper; Arbeidsnotat, 20011030)In this paper we develops a categorical theory of relations and use this formulation to define the notion of quantization for relations. Categories of relations are defined in the context of symmetric monoidal categories. They ... 
Causality in Scale Space as an Approach to Change Detection
(Journal article; Tidsskriftartikkel; Peer reviewed, 2012)Kernel density estimation and kernel regression are useful ways to visualize and assess the structure of data. Using these techniques we define a temporal scale space as the vector space spanned by bandwidth and a temporal ... 
Compatibility, multibrackets and integrability of systems of PDEs
(Journal article; Tidsskriftartikkel; Peer reviewed, 20080220)We establish an efficient compatibility criterion for a system of generalized complete intersection type in terms of certain multibrackets of differential operators. These multibrackets generalize the higher Jacobi Mayer ... 
Deformation of big pseudoholomorphic disks and application to the Hanh pseudonorm
(Journal article; Tidsskriftartikkel; Peer reviewed, 20030414)We simplify proof of the theorem that close to any pseudoholomorphic disk there passes a pseudoholomorphic disk of arbitrary close size with any predescribed sufficiently close direction. We apply these results to the ... 
DeltaProt : a software toolbox for comparative genomics
(Journal article; Tidsskriftartikkel; Peer reviewed, 2010) 
Differential invariants of the 2D conformal Lie algebra action
(Master thesis; Mastergradsoppgave, 20080215)In this thises we consider the Lie algebra that corresponds to the Lie pseudogroup of all conformal transformations on the plane. This conformal Lie algebra is canonically represented as a Lie algebra of vector fields ... 
Differential invariants of the motion group actions
(Working paper; Arbeidsnotat, 20071220)Differential invariants of a (pseudo)group action can vary when restricted to invariant submanifolds (differential equations). The algebra is still governed by the LieTresse theorem, but may change a lot. We describe ... 
Dimension of the solutions space of PDEs
(Conference object; Konferansebidrag, 20061026)We discuss the dimensional characterization of the solutions space of a formally integrable system of partial differential equations and provide certain formulas for calculations of these dimensional quantities. 
Discrimination of cod otolith shapes by two different Fourier methods
(Master thesis; Mastergradsoppgave, 20131216)In this thesis we have applied Fisher’s discrimination method to cod samples to discriminate between cod originating from the coastal cod stock and cod originating from the arctic cod stock. The discrimination is based ... 
Distributing a private key generator in Ad hoc Networks
(Master thesis; Mastergradsoppgave, 20090515)A Mobile Ad hoc Network (MANET) is a wireless network that does not rely on a fixed infrastructure. These characteristics make algorithms that route network traffic particularly vulnerable to attack. Mechanisms used to ... 
Dynamics and entropy in the Zhang model of SelfOrganized Criticality
(Working paper; Arbeidsnotat, 20050912)We give a detailed study of dynamical properties of the Zhang model, including evaluation of topological entropy and estimates for the Lyapunov exponents and the dimension of the attractor. In the thermodynamic limit ...