Sökning: "finite element method FEM"

Visar resultat 6 - 10 av 158 avhandlingar innehållade orden finite element method FEM.

1. 6. 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

3. 7. Stable FEM-FDTD Hybrid Method for Maxwell's Equations

   Författare :Thomas Rylander; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Finite Element Method; scattering; antennas; stability analysis; edge elements; Maxwell s equations; NASA almond; microwave circuits; mass lumping; proof of stability; explicit-implicit time-stepping; Finite-Differences Time-Domain;

   Sammanfattning : In this thesis edge elements are applied to solve several problems in computational electromagnetics. In particular, a hybrid scheme joining the Finite Element Method (FEM) and the Finite-Difference Time-Domain (FDTD) algorithm is developed, tested and exploited. LÄS MER

4. 8. Finite Element Modeling of the Human Head

   Författare :Svein Kleiven; KTH; []
   Nyckelord :Finite element method FEM ; Human head; brain; head injury; epidemiology; statistics; simulations.;

   Sammanfattning : The main objectives of the present thesis were to define the dimension of head injuries in Sweden over a longer period and to present a Finite Element (FE) model of the human head which can be used for preventive strategies in the future. The annual incidence of head injuries in Sweden between 1987 and 2000 was defined at over 22 000, cases most of which were mild head injuries. LÄS MER

5. 9. Inverse and optimization problems in electromagnetics -- a finite-element method perspective

   Författare :JOHAN WINGES; Chalmers tekniska högskola; []
   Nyckelord :MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; microwave measurements; computational electromagnetics; finite element method; optimization; inductive power transfer; compressed sensing; wireless power; brick-tetrahedron hybrid; parameter estimation; inverse problems;

   Sammanfattning : In this thesis, a selection of inverse and optimization problems are studied where the finite element method (FEM) serves as a comprehensive tool to solve electromagnetic field problems that lack an analytic solution. The inverse problems are typically formulated in terms of an optimization problem where the misfit between a measurement and the corresponding result of a computational model is minimized. LÄS MER

7. 10. Modelling of large deformation crack propagation based on the extended finite element method

   Författare :Martin Fagerström; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; crack propagation; strong discontinuities; material crack driving force; FEM; cohesive zone;

   Sammanfattning : This thesis is concerned with the finite element modelling of large deformation crack propagation, based on the extended finite element methodology. The benefit from this approach is the possibility of locally enriching the finite element space, i.e. to add a priori knowledge about the local behaviour of the solution in order to improve accuracy. LÄS MER