Advanced search

Showing result 16 - 20 of 50 swedish dissertations matching the above criteria.

  2. 16. 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. 17. Towards Enabling Exploration of Planetary Subterranean Environments using Unmanned Aerial Vehicles

    Author : Akash Patel; George Nikolakopoulos; Savvas Loizou; Luleå tekniska universitet; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Robotics and Artificial Intelligence; Robotik och artificiell intelligens;

    Abstract : This thesis presents a novel navigation framework established to enable the exploration of planetary subterranean areas with Unmanned Aerial Vehicles (UAVs). The key contributions of this thesis work form a robot-safe rapid navigation framework that utilizes a novel bifurcating frontier-based exploration approach. READ MORE

  5. 18. Experimental analysis of thermal mixing at reactor conditions

    Author : Mattia Bergagio; Henryk Anglart; Paolo Vinai; KTH; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; mixing estimator; empirical mode decomposition; Hilbert-Huang transform; uncertainty assessment; radial heat flux; Energy Technology; Energiteknik; Fysik; Physics;

    Abstract : High-cycle thermal fatigue arising from turbulent mixing of non-isothermal flows is a key issue associated with the life management and extension of nuclear power plants. The induced thermal loads and damage are not fully understood yet. READ MORE

  6. 19. Computational Aeroacoustics Based on Large Eddy Simulation and Acoustic Analogies

    Author : Mihai Mihaescu; Laszlo Fuchs; Strömningsteknik; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Mechanical engineering; hydraulics; plasma; Technological sciences; Teknik; fluiddynamik; plasmas; Gaser; fluid dynamics; Gases; Inhomogeneous Wave Equation; Acoustic Boundary Conditions; Acoustic Source Terms; LES; Computational Aeroacoustics; Turbulent Flows; vacuum technology; vibration and acoustic engineering; Maskinteknik; hydraulik; vakuumteknik; vibrationer; akustik; Computational Aeroacoustics;

    Abstract : The thesis presents a numerical method developed by the author and its applications for computing the generated sound by an unsteady flow field and its propagation. The full equations of motion for compressible and unsteady flows describe both flow field and sound generation and propagation. READ MORE

  7. 20. Design and Experiments with High Power Microwave Sources : The Virtual Cathode Oscillator

    Author : Cecilia Möller; Nils Brenning; Stefan Silfverskiöld; KTH; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; High Power Microwaves Vircator;

    Abstract : High-Power Microwaves (HPM) can be used to intentionally disturb or destroy electronic equipment at a distance by inducing high voltages and currents.This thesis presents results from simulations and experiments with a narrow band HPM source, the vircator. READ MORE