Sökning: "a priori error estimation"

Visar resultat 1 - 5 av 18 avhandlingar innehållade orden a priori error estimation.

1. 1. Low-angle estimation : Models, methods and bounds

   Författare :Katarina Boman; Peter Stoica; Uppsala universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Signal Processing; Signalbehandling;

   Sammanfattning : In this work we study the performance of elevation estimators and lower bounds on the estimation error variance for a low angle target in a smooth sea scenario using an array antenna. The article is structured around some key assumptions on multipath knowledge, signal parameterization and noise covariance, giving the reader a framework in which Maximum Likelihood estimators exploiting different á priori information can be found. LÄS MER

3. 2. Electromagnetic Modelling for the Estimation of Wood Parameters

   Författare :Therese Sjödén; Sven Nordebo; Börje Nilsson; Andreas Fhager; Växjö universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Cramér Rao bound; electromagnetic modelling; estimation; grain angle; microwave; wood properties.; Cramér Rao-gräns; elektromagnetisk modellering; estimering; fibervinkel; mikrovågor; träegenskaper.; Engineering physics; Teknisk fysik; Physics; Fysik;

   Sammanfattning : Spiral grain in trees causes trouble to the wood industry, since boards sawn from trees with large grain angle have severe problems with form stability. Measurements of the grain angle under bark enable the optimisation of the refining process. LÄS MER

4. 3. Multiscale Methods and Uncertainty Quantification

   Författare :Daniel Elfverson; Axel Målqvist; Frédéric Legoll; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; multiscale methods; finite element method; discontinuous Galerkin; Petrov-Galerkin; a priori; a posteriori; complex geometry; uncertainty quantification; multilevel Monte Carlo; failure probability; Beräkningsvetenskap med inriktning mot numerisk analys; Scientific Computing with specialization in Numerical Analysis;

   Sammanfattning : In this thesis we consider two great challenges in computer simulations of partial differential equations: multiscale data, varying over multiple scales in space and time, and data uncertainty, due to lack of or inexact measurements.We develop a multiscale method based on a coarse scale correction, using localized fine scale computations. LÄS MER

5. 4. Automation of Computational Mathematical Modeling

   Författare :Anders Logg; Göteborgs universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; computational mathematical modeling; automation; adaptivity; multi-adaptivity; individual time steps; dual problem; a priori; a posteriori; model reduction; individual time steps;

   Sammanfattning : This thesis concerns the Automation of Computational Mathematical Modeling (CMM), involving the key steps of automation of (i) discretization, (ii) discrete solution, (iii) error control, (iv) modeling, and (v) optimization. The automation of (i)--(ii) is realized through multi-adaptive Galerkin methods on general discretizations of space-time with time steps variable in space. LÄS MER

7. 5. Finite Element Methods for Thin Structures with Applications in Solid Mechanics

   Författare :Karl Larsson; Mats G Larson; Garth N Wells; Umeå universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; a priori error estimation; finite element method; discontinuous Galerkin; corotation; Kirchhoff-Love plate; curved beam; biharmonic equation; Mathematics; matematik;

   Sammanfattning : Thin and slender structures are widely occurring both in nature and in human creations. Clever geometries of thin structures can produce strong constructions while requiring a minimal amount of material. LÄS MER