Sökning: "local stability"

Visar resultat 21 - 25 av 345 avhandlingar innehållade orden local stability.

  1. 21. Modeling and Control of VSC-HVDC Transmissions

    Författare :Hector Latorre; Mehrdad Ghandhari; Luis Rouco; KTH; []
    Nyckelord :Control Lyapunov Functions; Energy Function; Modal Analysis; Transient Stability; Voltage Stability; VSC-HVDC Transmission.; TECHNOLOGY; TEKNIKVETENSKAP;

    Sammanfattning : Presently power systems are being operated under high stress level conditions unforeseen at the moment they were designed. These operating conditions have negatively impacted reliability, controllability and security margins. FACTS devices and HVDC transmissions have emerged as solutions to help power systems to increase the stability margins. LÄS MER

  3. 22. Hybrid Methods for Unsteady Fluid Flow Problems in Complex Geometries

    Författare :Jing Gong; Jan Nordström; Gunilla Efraimsson; Mark H. Carpenter; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; hybrid methods; finite difference methods; finite volume methods; coupling procedure; stability; efficiency; artificial dissipation; Numerical analysis; Numerisk analys; Scientific Computing; Beräkningsvetenskap; Beräkningsvetenskap med inriktning mot numerisk analys;

    Sammanfattning : In this thesis, stable and efficient hybrid methods which combine high order finite difference methods and unstructured finite volume methods for time-dependent initial boundary value problems have been developed. The hybrid methods make it possible to combine the efficiency of the finite difference method and the flexibility of the finite volume method. LÄS MER

  4. 23. Comparing No-Party Participatory Regimes : Why Uganda Succeeded and Others Failed

    Författare :Mose Auyeh; Sten Widmalm; Magdalena Inkinen; Anirudh Krishna; Uppsala universitet; []
    Nyckelord :SAMHÄLLSVETENSKAP; SOCIAL SCIENCES; democracy; Uganda; stability; No-Party Participatory Regimes; Ghana; Libya; Pakistan; governance; responsiveness; effectiveness; legitimacy; Political science; Statsvetenskap;

    Sammanfattning : The objective of this dissertation is to evaluate the performance of the no-party participatory regime (NPPR) model in a few selected countries. Such a regime, it was claimed, would give rise to a real and true democracy, would serve the people better, and would protect them against what many leaders saw as divisive party politics. LÄS MER

  5. 24. Oversampled radial basis function methods for solving partial differential equations

    Författare :Igor Tominec; Elisabeth Larsson; Bengt Fornberg; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; radial basis function; PDE; oversampling; stability; RBF-FD; RBF-PUM; unfitted;

    Sammanfattning : Partial differential equations (PDEs) describe complex real-world phenomena such as weather dynamics,  object deformations, financial trading prices, and fluid-structure interaction.  The solutions of PDEs are commonly used to enhance the understanding of these phenomena and also as leverage to make technological improvements to consumer products. LÄS MER

  7. 25. Numerical analyses of stability of a gradually raised tailings dam

    Författare :Muhammad Auchar Zardari; Daichao Sheng; Luleå tekniska universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; tailings dams; consolidation; rockfill berms; slope stability; corner; internal erosion; finite element analysis; Soil Mechanics; Geoteknik;

    Sammanfattning : Numerical analyses are presented in this thesis to address potential stability problems that may occur during gradual raisings and under seismic loading conditions of Aitik tailings dam in northern Sweden. The dam is mainly raised using upstream construction method. It is planned to raise the dam gradually in several stages. LÄS MER