Search for dissertations about: "dalarsson"

Found 4 swedish dissertations containing the word dalarsson.

2. 1. Online power transformer diagnostics using multiple modes of microwave radiation

   Author : Mariana Dalarsson; Martin Norgren; Sven Nordebo; KTH; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; inverse problem; multiple modes; power transformers;

   Abstract : In the present thesis, we propose and investigate a new approach to diagnose the effects of the various degradation mechanisms, including thermal degradation at hot spots, winding deformations due to the mechanical forces from short circuit currents, partial discharges due to local electric field surges, and increased moisture levels in the cellulose insulation due to decomposition, that affect electric power transformers during their normal operation in an electric power grid.Although the proposed diagnostics method can in principle be used to detect various degradation mechanisms mentioned above, we focus in the present thesis on mechanical deformations of transformer winding structures. READ MORE

4. 2. Perturbation approach to reconstructions of boundary deformations in waveguide structures

   Author : Mariana Dalarsson; Martin Norgren; Sergei Tretyakov; KTH; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; inverse problems; waveguides; microwaves; perturbation theory; Electrical Engineering; Elektro- och systemteknik;

   Abstract : In this thesis we develop inverse scattering algorithms towards the ultimate goal of online diagnostic methods. The aim is to detect structural changes inside power transformers and other major power grid components, like generators, shunt reactors etc. READ MORE

5. 3. Optimization and Physical Bounds for Passive and Non-passive Systems

   Author : Yevhen Ivanenko; Sven Nordebo; Börje Nilsson; Mats Gustafsson; Mariana Dalarsson; Aaron Welters; Linnéuniversitetet; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Convex optimization; physical bounds; Herglotz functions; quasi-Herglotz functions; passive systems; non-passive systems; approximation; absorption in lossy media; Waves; Signals and Systems; Vågor; signaler och system;

   Abstract : Physical bounds in electromagnetic field theory have been of interest for more than a decade. Considering electromagnetic structures from the system theory perspective, as systems satisfying linearity, time-invariance, causality and passivity, it is possible to characterize their transfer functions via Herglotz functions. READ MORE

6. 4. Wave propagation in graded material composites with extraordinary properties

   Author : Brage B. Svendsen; Mariana Dalarsson; Martin Norgren; Astrid Aksnes; KTH; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; gradient-index; waveguides; gold nanoparticles; cancer treatment; left-handed media; negative index materials; metamaterials; Electrical Engineering; Elektro- och systemteknik;

   Abstract : I denna avhandling studeras elektromagnetisk vågutbredning i graderade materialkompositer med extraordinära egenskaper. Två sådana materialkompositsystem studeras särskilt, med hjälp av både analytiska och beräkningstekniska elektromagnetiska metoder. READ MORE