Sökning: "stiff problems"

Visar resultat 1 - 5 av 23 avhandlingar innehållade orden stiff problems.

  1. 1. High order summation-by-parts methods in time and space

    Författare :Tomas Lundquist; Jan Nordström; Peter Eliasson; David A. Kopriva; Linköpings universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; summation-by-parts; time integration; stiff problems; weak initial conditions; high order methods; simultaneous-approximation-term; finite difference; discontinuous Galerkin; spectral methods; conservation; energy stability; complex geometries; non-conforming grid interfaces; interpolation;

    Sammanfattning : This thesis develops the methodology for solving initial boundary value problems with the use of summation-by-parts discretizations. The combination of high orders of accuracy and a systematic approach to construct provably stable boundary and interface procedures makes this methodology especially suitable for scientific computations with high demands on efficiency and robustness. LÄS MER

  3. 2. Runge-Kutta Solution of Initial Value Problems: Methods, Algorithms and Implementation

    Författare :Hans Olsson; Institutionen för datavetenskap; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Computer science; stiffness; software; computational process; differential algebraic equations; ordinary differential equations; Runge-Kutta; initial value problems; time-stepping; system; kontroll; numerisk analys; Datalogi; control; numerical analysis; systems;

    Sammanfattning : The last decades have seen a strongly increasing use of computers for modeling larger and more complex systems. This has been made possible by a combination of increasing computer power and easy-to-use graphical modeling environments and libraries of components. LÄS MER

  4. 3. An Integration-Reduction Scheme for Simulation of Large Systems with Local Nonlinearity and Uncertainty - Application to moving load problems in railway mechanics

    Författare :Sadegh Rahrovani; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Monte-Carlo simulations; time-integration; moving load problems; reliability analysis; exponential integrator; symplectic integrator; modal dominancy analysis;

    Sammanfattning : The focus of this research is mainly on computational efficiency, as future work is planned for reliability analysis that will be combined with design optimisation. Both these fields are known to be notoriously computationally demanding. LÄS MER

  5. 4. Computational Homogenization of Transient Problems - Application to Porous Media

    Författare :Fang Su; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; consolidation; Representative Volume Element RVE ; homogenization; FE2;

    Sammanfattning : This thesis is devoted to the development and analysis of a homogenization-basedcomputational strategy for simulating the transient and nonlinear coupled consolidationproblem in micro-heterogeneous porous media. A variational framework and the pertinentfinite element (FE) strategy, based on a generalized macro-homogeneity condition,are proposed for the spatial homogenization of a class of transient problems, wherebythe classical assumption of first order homogenization is adopted. LÄS MER

  7. 5. Control Design and Performance Analysis of force Reflective Teleoperators - A Passivity Based Approach

    Författare :Henrik Flemmer; KTH; []
    Nyckelord :Teleoperator; Force Feedback; Passivity; Stiff Contacts; Control; Robustness; Transparency; Bone Milling; Uncertainty;

    Sammanfattning : In this thesis, the problem of controlling a surgical masterand slave system with force reflection is studied. The problemof stiff contacts between the slave and the environment isgiven specific attention. The work has been carried out at KTHbased on an initial cooperation with Karolinska Sjukhuset. LÄS MER