Sökning: "inverse scattering"

Visar resultat 21 - 25 av 62 avhandlingar innehållade orden inverse scattering.

1. 21. Inverse and optimization problems in electromagnetics -- a finite-element method perspective

   Författare :JOHAN WINGES; Chalmers tekniska högskola; []
   Nyckelord :MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; microwave measurements; computational electromagnetics; finite element method; optimization; inductive power transfer; compressed sensing; wireless power; brick-tetrahedron hybrid; parameter estimation; inverse problems;

   Sammanfattning : In this thesis, a selection of inverse and optimization problems are studied where the finite element method (FEM) serves as a comprehensive tool to solve electromagnetic field problems that lack an analytic solution. The inverse problems are typically formulated in terms of an optimization problem where the misfit between a measurement and the corresponding result of a computational model is minimized. LÄS MER

3. 22. Adaptive finite element/difference methods for time-dependent inverse scattering problems

   Författare :Larisa Beilina; Göteborgs universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES;

   Sammanfattning : In this thesis we develop adaptive hybrid finite element/difference methods for inverse time-domain acoustic and elastic scattering, where we seek to find the location and form of a (small) unknown object inside a large homogeneous body from measured wave-reflection data. We formulate the inverse problem as an optimal control problem, where we seek to reconstruct unknown material coefficients with best least squares wave fit to data. LÄS MER

4. 23. Wave Propagation in Structural Elements - Direct and Inverse Problems in the Time Domain

   Författare :Peter Folkow; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; integro-differential equations; non-uniform beams; wave splitting; wave propagator; finite difference; Timoshenko beam; imbedding; Mindlin plate; inverse problem; viscoelastic damping; nonlinear rod; transient wave propagation; Green function;

   Sammanfattning : The subject of this thesis is direct and inverse wave propagation problems in structural elements. The considered structures are beams, plates and rods. The models for the beams and the plates are based on linear theory, while the rods are assumed to be nonlinear. The greater part of the work concerns the Timoshenko beam. LÄS MER

5. 24. CONTRIBUTION TO QUANTITATIVE MICROWAVE IMAGING TECHNIQUES FOR BIOMEDICAL APPLICATIONS

   Författare :Tommy Henriksson; Ylva Bäcklund; Magnus Otterskog; Hans Sköld; Jean-Charles Bolomey; Nadine Joachimowicz; Alain Joisel; Paul M. Meaney; Christian Pichot; Mälardalens högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Quantitative Microwave Imaging. Inverse Problems; Nonliear Inverse Scattering; Diffraction Tomography; Breast Tumor Detection; Biomedical Imaging; Mammography; Calibration; Modeling; Planar 2.45 GHz Microwave Camera; Robot-based flexible multi-frequency data acquisition; Electrophysics; Elektrofysik; Elektronik; Electronics;

   Sammanfattning : This dissertation presents a contribution to quantitative microwave imaging for breast tumor detection. The study made in the frame of a joint supervision Ph.D. thesis between University Paris-SUD 11 (France) and Mälardalen University (Sweden), has been conducted through two experimental microwave imaging setups, the existing 2. LÄS MER

7. 25. Fundamental research on supercritical fluid extraction kinetics : From on-line measurements to inverse modeling

   Författare :Victor Abrahamsson; Centrum för analys och syntes; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; supercritical fluid extraction; supercritical fluid chromatography; linseed; microalgae; extraction kinetics; inverse modeling; curve resolution;

   Sammanfattning : Supercritical fluid extraction is an extraction technique suitable for lipophilic compounds from solid samples. Most commonly supercritical carbon dioxide is the main component in the extraction phase, rendering the technique relatively environmentally benign. LÄS MER