Sökning: "Markov Random Field."

Visar resultat 1 - 5 av 26 avhandlingar innehållade orden Markov Random Field..

1. 1. Random Geometry and Reinforced Jump Processes

   Författare :Tuan-Minh Nguyen; Probability and Inference Theory Group; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; random polygons; products of random matrices; vertex-reinforced jump processes; pseudotrajectories; random walks in simplexes; Markov chains in a general state space;

   Sammanfattning : This thesis comprises three papers studying several mathematical models related to geometric Markov processes and random processes with reinforcements. The main goal of these works is to investigate the dynamics as well as the limiting behaviour of the models as time goes to infinity, the existence of invariant measures and limiting distributions, the speed of convergence and other interesting relevant properties. LÄS MER

3. 2. Models and Methods for Random Fields in Spatial Statistics with Computational Efficiency from Markov Properties

   Författare :David Bolin; Matematisk statistik; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; random fields; Gaussian Markov random fields; Matérn covariances; stochastic partial differential equations; Computational efficiency;

   Sammanfattning : The focus of this work is on the development of new random field models and methods suitable for the analysis of large environmental data sets. A large part is devoted to a number of extensions to the newly proposed Stochastic Partial Differential Equation (SPDE) approach for representing Gaussian fields using Gaussian Markov Random Fields (GMRFs). LÄS MER

4. 3. Spatio-Temporal Estimation for Mixture Models and Gaussian Markov Random Fields - Applications to Video Analysis and Environmental Modelling

   Författare :Johan Lindström; Matematisk statistik; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; vegetation; time series analysis; video segmentation; spatio-temporal modelling; precipitation; Markov chain Monte Carlo; Gaussian Markov random fields; expectation maximisation; change point detection; Bayesian recursive estimation; African Sahel; adaptive Gaussian mixtures;

   Sammanfattning : In this thesis computationally intensive methods are used to estimate models and to make inference for large, spatio-temporal data sets. The thesis is divided into two parts: the first two papers are concerned with video analysis, while the last three papers model and investigate environmental data from the Sahel area in northern Africa. LÄS MER

5. 4. Statistical methods in medical image estimation and sparse signal recovery

   Författare :Fekadu Lemessa Bayisa; Jun Yu; Ottmar Cronie; Henning Omre; Umeå universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; Computed tomography; magnetic resonance imaging; Gaussian mixture model; skew-Gaussian mixture model; hidden Markov random field; hidden Markov model; supervised statistical learning; synthetic CT images; pseudo-CT images; spike and slab prior; adaptive algorithm;

   Sammanfattning : This thesis presents work on methods for the estimation of computed tomography (CT) images from magnetic resonance (MR) images for a number of diagnostic and therapeutic workflows. The study also demonstrates sparse signal recovery method, which is an intermediate method for magnetic resonance image reconstruction. LÄS MER

7. 5. Spatial inference for non-lattice data using Markov Random fields

   Författare :Linda Werner Hartman; Matematisk statistik; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES;

   Sammanfattning : This thesis deals with how computationally effective lattice models could be used for inference of data with a continuous spatial index. The fundamental idea is to approximate a Gaussian field with a Gaussian Markov random field (GMRF) on a lattice. LÄS MER