Sökning: "Andreas Petersson"

Visar resultat 1 - 5 av 8 avhandlingar innehållade orden Andreas Petersson.

  1. 1. Evolution of continental crust in the Proterozoic : growth and reworking in orogenic systems

    Författare :Andreas Petersson; Berggrundsgeologi; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; crustal reworking; Proterozoic; O-isotopes; Lu–Hf; U–Pb; zircon; Crustal growth;

    Sammanfattning : To understand the growth of continental crust, the balance between juvenile mantle derived extraction, infracrustal reworking and crustal recycling, needs to be estimated. Since the beginning of the century, the use of coupled in situ zircon U–Pb, Lu–Hf and O isotope analyses as a tool to address these questions have increased exponentially. LÄS MER

  2. 2. Analysis, Modeling and Control of Doubly-Fed Induction Generators for Wind Turbines

    Författare :Andreas Petersson; Chalmers University of Technology; []
    Nyckelord :current control; voltage sag; wind turbine; wind energy; doubly-fed induction generator; power quality;

    Sammanfattning : This thesis deals with the analysis, modeling, and control of the doubly-fed induction generator (DFIG) for wind turbines. Different rotor current control methods are investigated with the objective of eliminating the influence of the back electromotive force (EMF), which is that of, in control terminology, a load disturbance, on the rotor current. LÄS MER

  3. 3. Analysis, Modeling and Control of Doubly-Fed Induction Generators for Wind Turbines

    Författare :Andreas Petersson; Chalmers University of Technology; []
    Nyckelord :;

    Sammanfattning : This thesis deals with the analysis, modeling, and control of the doubly-fed induction machine used as a wind turbine generator. The energy efficiency of wind turbine systems equipped with doubly-fed induction generators are compared to other wind turbine generator systems. LÄS MER

  4. 4. Approximating Stochastic Partial Differential Equations with Finite Elements: Computation and Analysis

    Författare :Andreas Petersson; Chalmers University of Technology; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Lévy process; Lyapunov equation; white noise; finite element method; multilevel Monte Carlo; Monte Carlo; multiplicative noise; asymptotic mean square stability; stochastic heat equation; covariance operator; weak convergence; generalized Wiener process; numerical approximation; stochastic wave equation; Stochastic partial differential equations;

    Sammanfattning : Stochastic partial differential equations (SPDE) must be approximated in space and time to allow for the simulation of their solutions. In this thesis fully discrete approximations of such equations are considered, with an emphasis on finite element methods combined with rational semigroup approximations. LÄS MER

  5. 5. Computational Aspects of Lévy-Driven SPDE Approximations

    Författare :Andreas Petersson; Göteborgs universitet; Göteborgs universitet; Gothenburg University; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; multilevel Monte Carlo; numerical approximation of stochastic differential equations; multiplicative noise; Lévy processes; finite element method; variance redons; Monte Carlo; weak convergence; Lévy processes;

    Sammanfattning : In order to simulate solutions to stochastic partial differential equations (SPDE) they must be approximated in space and time. In this thesis such fully discrete approximations are considered, with an emphasis on finite element methods combined with rational semigroup approximations. There are several notions of the error resulting from this. LÄS MER