Search for dissertations about: "harmonic propagation"

Showing result 6 - 10 of 31 swedish dissertations containing the words harmonic propagation.

  2. 6. Managing uncertainties through efficient calculation of transients and harmonic propagation in power systems

    Author : Oscar Lennerhag; Math Bollen; Jan Lundquist; David Thomas; Luleå tekniska universitet; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Overvoltages; harmonics; uncertainties; stochastic methods; Electric Power Engineering; Elkraftteknik;

    Abstract : The electric power system is undergoing changes including large-scale introduction of renewable energy sources together with HVDC/FACTS, changes in the network such as increased amount of high voltage cables, industrial electrification, and changes in the load composition. These changes will impact the system in different ways and lead to challenges that must be addressed to facilitate planning, dimensioning, and operation of the system in a secure and economical way. READ MORE

  4. 7. Topology optimization for acoustic wave propagation problems

    Author : Eddie Wadbro; Martin Berggren; Uppsala universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Scientific Computing; Beräkningsvetenskap;

    Abstract : The aim of this study is to develop numerical techniques for the analysis and optimization of acoustic horns for time harmonic wave propagation. An acoustic horn may be viewed as an impedance transformer, designed to give an impedance matching between the feeding waveguide and the surrounding air. READ MORE

  5. 8. Topics in Analysis and Computation of Linear Wave Propagation

    Author : Mohammad Motamed; Olof Runborg; Shi Jin; KTH; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Numerical analysis; Numerisk analys;

    Abstract : This thesis concerns the analysis and numerical simulation of wave propagation problems described by systems of linear hyperbolic partial differential equations. A major challenge in wave propagation problems is numerical simulation of high frequency waves. READ MORE

  6. 9. Numerical Methods for Aeroacoustic Analysis of Turbomachines

    Author : Daniel Lindblad; Chalmers tekniska högskola; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Stability Analysis; Acoustic Analogy; Tonal Noise; Nonreflecting Boundary Conditions; Duct Modes; Turbomachinery; Harmonic Balance; Ffowcs Williams - Hawkings; Time Sampling; Aliasing;

    Abstract : Numerical simulations are important tools for developing new aircraft that can meet future needs. When numerical simulations are used to compute aircraft noise, a two-step procedure is often employed. In the first step, the noise sources are determined using, e.g. READ MORE

  7. 10. Modelling tools for quieter vehicles : Waves in poro– and visco–elastic continua

    Author : Martin Östberg; Leif Kari; Jenny Jerrelind; Sergey Sorokin; KTH; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Vibro-acoutics; poro-elastic; visco-elastic; reduced models; Harmonic expansion; wave guide;

    Abstract : New modelling tools intended to contribute to the development of components for quieter vehicles are developed. The tools are based on continuum models for wave propagation in poro– and visco–elastic media. By using geometric attributes of the studied components, the computational cost may be radically decreased compared to traditional methods. READ MORE