Sökning: "Landweber"

Visar resultat 1 - 5 av 7 avhandlingar innehållade ordet Landweber.

1. 1. Data Assimilation in Fluid Dynamics using Adjoint Optimization

   Författare :Johan Lundvall; Vladimir Kozlov; Per Weinerfelt; Matts Karlsson; Anders Szepessy; Linköpings universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Data assimilation; Inverse problem; Adjoint optimization; Burgers equation; nonlinear; Landweber; Initial pressure; Euler flow; Applied mathematics; Tillämpad matematik;

   Sammanfattning : Data assimilation arises in a vast array of different topics: traditionally in meteorological and oceanographic modelling, wind tunnel or water tunnel experiments and recently from biomedical engineering. Data assimilation is a process for combine measured or observed data with a mathematical model, to obtain estimates of the expected data. LÄS MER

3. 2. The Use of Landweber Algorithm in Image Reconstruction

   Författare :Touraj Nikazad; Tommy Elfving; George Baravdish; Linköpings universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; convex feasibility; projection methods; simultaneous algorithms; iterative methods; stopping rules; semi-convergence; Numerical analysis; Numerisk analys;

   Sammanfattning : Ill-posed sets of linear equations typically arise when discretizing certain types of integral transforms. A well known example is image reconstruction, which can be modelled using the Radon transform. After expanding the solution into a finite series of basis functions a large, sparse and ill-conditioned linear system arises. LÄS MER

4. 3. Algebraic Reconstruction Methods

   Författare :Touraj Nikazad; Tommy Elfving; Constantin Popa; Linköpings universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; iterative methods; image reconstruction; ART; Cimmino; Kaczmarz; Landweber; sequential iteration; simultaneous iteration; block iteration; semi-convergence; relaxation parameters; stopping rules; discrepancy principle; Numerical analysis; Numerisk analys;

   Sammanfattning : Ill-posed sets of linear equations typically arise when discretizing certain types of integral transforms. A well known example is image reconstruction, which can be modeled using the Radon transform. After expanding the solution into a finite series of basis functions a large, sparse and ill-conditioned linear system occurs. LÄS MER

5. 4. Inverse Mathematical Models for Brain Tumour Growth

   Författare :Rym Jaroudi; George Baravdish; Tomas Johansson; Trucu Dumitru; Linköpings universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES;

   Sammanfattning : We study the following well-established model of reaction-diffusion type for brain tumour growth:This equation describes the change over time of the normalised tumour cell density u as a consequence of two biological phenomena: proliferation and diffusion.We discuss a mathematical method for the inverse problem of locating the brain tumour source (origin) based on the reaction-diffusion model. LÄS MER

7. 5. Accelerated Dirichlet-Robin Alternating Algorithm for Solving the Cauchy Problem for an Elliptic Equation using Krylov Subspaces

   Författare :Jennifer Chepkorir; Vladimir Kozlov; Fredrik Berntsson; Linus Carlsson; Linköpings universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES;

   Sammanfattning : In this thesis, we study the Cauchy problem for an elliptic equation. We use Dirichlet-Robin iterations for solving the Cauchy problem. This allows us to include in our consideration elliptic equations with variable coefficient as well as Helmholtz type equations. LÄS MER