Sökning: "Differential algebraic equations"

Visar resultat 21 - 25 av 56 avhandlingar innehållade orden Differential algebraic equations.

  1. 21. Algebraic Approaches to Normal Forms and Zero Dynamics

    Författare :Håkan Fortell; Linköpings universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY;

    Sammanfattning : The normal form of affine state space systems has been extensively studied during the last decade and it has found several important applications. Two such applications are exact input-output linearization and sliding mode control. A property of affine nonlinear systems that is simple to compute given a normal form is the zero dynamics. LÄS MER

  3. 22. Admissible transformations and the group classification of Schrödinger equations

    Författare :Celestin Kurujyibwami; Peter Basarab-Horwath; Roman Popovych; Pontelis Damianou; Linköpings universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES;

    Sammanfattning : We study admissible transformations and solve group classification problems for various classes of linear and nonlinear Schrödinger equations with an arbitrary number n of space variables.The aim of the thesis is twofold. LÄS MER

  4. 23. Explicit algebraic subgrid-scale stress and passive scalar flux modeling in large eddy simulation

    Författare :Amin Rasam; Arne V. Johansson; Shia-Hui Peng; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Turbulence; Large eddy simulation; explicit algebraic subgrid-scale model; passive scalar; stochastic modeling; backscatter; Fluid mechanics; Strömningsmekanik;

    Sammanfattning : The present thesis deals with a number of challenges in the field of large eddy simulation (LES). These include the performance of subgrid-scale (SGS) models at fairly high Reynolds numbers and coarse resolutions, passive scalar and stochastic modeling in LES. LÄS MER

  5. 24. Numerical Computations with Fundamental Solutions

    Författare :Per Sundqvist; Henrik Brandén; Sverker Holmgren; Alison Ramage; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; fundamental solution; partial differential equation; partial difference equation; iterative method; preconditioner; boundary method; Numerical Analysis; Numerisk analys;

    Sammanfattning : Two solution strategies for large, sparse, and structured algebraic systems of equations are considered. The first strategy is to construct efficient preconditioners for iterative solvers. The second is to reduce the sparse algebraic system to a smaller, dense system of equations, which are called the boundary summation equations. LÄS MER

  7. 25. Robust Preconditioners Based on the Finite Element Framework

    Författare :Erik Bängtsson; Maya Neytcheva; Per Lötstedt; Svetozar Margenov; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; FEM; iterative solution method; algebraic multilevel preconditioner; sparse approximate inverse; block preconditioner; Schur complement approximation; nonsymmetric saddle point matrix; isostatic glacial adjustment; pre-stress advection; elasticity; viscoelasticity; in compressible solid; ABAQUS; BEM DDM; Scientific Computing; Beräkningsvetenskap;

    Sammanfattning : Robust preconditioners on block-triangular and block-factorized form for three types of linear systems of two-by-two block form are studied in this thesis. The first type of linear systems, which are dense, arise from a boundary element type of discretization of crack propagation problems. LÄS MER