Sökning: "Nonsmooth problems"

Visar resultat 1 - 5 av 6 avhandlingar innehållade orden Nonsmooth problems.

1. 1. Ghosts and machines : regularized variational methods for interactive simulations of multibodies with dry frictional contacts

   Författare :Claude Lacoursière; Bo Kåggström; Ander Klarbring; Umeå universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Discrete mechanics; Variational method; Contact problems; Impacts; Least action principle; Saddle point problems; Lagrange Multipliers; Constrained systems; Multibody Systems; Numerical regularization; Constraint realization; Constraint stabilization; Dry friction; Differential Algebraic Equations; Nonsmooth problems; Linear Complementarity; Quaternion algebra; Numerical linear algebra; Physics modeling; Interactive simulation; Numerical stability; Rigid body dynamics; Dissipative systems; Computational physics; Beräkningsfysik;

   Sammanfattning : A time-discrete formulation of the variational principle of mechanics is used to provide a consistent theoretical framework for the construction and analysis of low order integration methods. These are applied to mechanical systems subject to mixed constraints and dry frictional contacts and impacts---machines. LÄS MER

3. 2. Computational Nonsmooth Mechanics

   Författare :Peter W. Christensen; J.A.C. Martins; Linköpings universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY;

   Sammanfattning : This thesis concerns the application of modern methods from the field of mathematical programming for solving certain problems of nonsmooth mechanics. Attention is given to contact problems with friction as well as plasticity problems. LÄS MER

4. 3. Numerical Analysis of Evolution Problems in Multiphysics

   Författare :Anna Persson; Göteborgs universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; regularity; generalized finite element; localized orthogonal decomposition; multiscale; finite element method; Thermoelasticity; Riccati equations; thermistor; linear elasticity; Joule heating; parabolic equations; Regularity; generalized finite element; localized orthogonal decomposition; multiscale finite element method; Thermoelasticity; Riccati equations; thermistor; linear elasticity; Joule heating; parabolic equations;

   Sammanfattning : In this thesis we study numerical methods for evolution problems in multiphysics. The term multiphysics is commonly used to describe physical phenomena that involve several interacting models. Typically, such problems result in coupled systems of partial differential equations. LÄS MER

5. 4. Convergence Analysis and Improvements for Projection Algorithms and Splitting Methods

   Författare :Mattias Fält; Institutionen för reglerteknik; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; First-order methods; Convex Optimization; Nonsmooth Optimization; Large-scale Optimization; Iterative Methods; Douglas-Rachford splitting; Line Search;

   Sammanfattning : Non-smooth convex optimization problems occur in all fields of engineering. A common approach to solving this class of problems is proximal algorithms, or splitting methods. These first-order optimization algorithms are often simple, well suited to solve large-scale problems and have a low computational cost per iteration. LÄS MER

7. 5. Error Analysis and Smoothing Properties of Discretized Deterministic and Stochastic Parabolic Problems

   Författare :Yubin Yan; Göteborgs universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES;

   Sammanfattning : In this thesis we consider smoothing properties and approximation of time derivatives for parabolic equations and error estimates for stochastic parabolic partial differential equations approximated by the finite element method. In the first two papers, we study smoothing properties and approximation of the time derivative in time discretization schemes with constant and variable time steps for an abstract homogeneous linear parabolic problem. LÄS MER