Search for dissertations about: "Multiple modes"

Showing result 1 - 5 of 167 swedish dissertations containing the words Multiple modes.

  1. 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

  2. 2. Systematic Antenna Design Using the Theory of Characteristic Modes

    Author : Zachary Miers; Institutionen för elektro- och informationsteknik; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Theory of Characteristic Modes; Antenna Design; Antenna; Characteristic Modes; Computational Electromagnetics; MIMO Systems; MIMO Antenna; MIMO; Mutual Coupling; Mobile Antenna;

    Abstract : The day Faraday moved a magnet in and out of a wire loop and detected the time-varying magnetic field, the first wireless transmitter / receiver system was created and the world was changed forever. However, it took almost fifty years for Heinrich Hertz to use Maxwell's equations and Faraday's insights in his professorship at Karlsruhe to create the first electromagnetic wireless communication system using a spark gap dipole transmitter and a loop antenna-based receiver. READ MORE

  3. 3. E-Government Collaboration in the Swedish Public Sector : Multiple Studies on Collaboration Facilitators and Collaboration Modes

    Author : Carl-Mikael Lönn; Christer Magnusson; Paul Johannesson; Pontus Johnson; Stockholms universitet; []
    Keywords : SAMHÄLLSVETENSKAP; SOCIAL SCIENCES; Computer and Systems Sciences; data- och systemvetenskap;

    Abstract : Collaboration in the public sector is imperative to achieve e-government objectives such as improved efficiency and effectiveness of public administration and improved quality of public services. Collaboration across organizational and institutional boundaries requires public organizations to share e-government systems and services through for instance, interoperable information technology and processes. READ MORE

  4. 4. Decoupling and Evaluation of Multiple Antenna Systems in Compact MIMO Terminals

    Author : Hui Li; Sailing He; Cyril Luxey; KTH; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Multiple antennas; mutual coupling; compact antennas; frequency reconfigurable antennas; pattern reconfigurable antennas; meta-material antennas; mobile antennas; fractal antennas; collocated antennas; antenna measurement.;

    Abstract : Research on multiple antenna systems has been a hot topic in recent years due to the demands for higher transmission rate and more reliable link in rich scattering environment in wireless communications. Using multiple antennas at both the transmitter side and the receiver side increases the channel capacity without additional frequency spectrum and transmitted power. READ MORE

  5. 5. Multiple stressors in rotifer communities: : Effects of predation, climate change, and brownification

    Author : Huan Zhang; Enhet akvatisk ekologi; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Climate change; community dynamic; brownification; heat wave; inducible defense; rotifer; plasticity; multiple stressors; Predation; prey;

    Abstract : Most organisms on Earth live in an environment where they are exposed to multiple pressures, including predation and climate change. In many aquatic ecosystems, organisms have to handle additional challenges such as brownification, co-occurring with climate warming. READ MORE