Sökning: "the finite element method"

Visar resultat 31 - 35 av 840 avhandlingar innehållade orden the finite element method.

1. 31. 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

3. 32. 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

4. 33. Shape Optimization for Acoustic Wave Propagation Problems

   Författare :Rajitha Udawalpola; Martin Berggren; Pekka Neittaanmäki; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; shape optimization; design optimization; acoustic wave propagation; Helmholtz equation; Boundary Element Method; Finite Element Method; inverse problems; adjoint method; gradient-based optimization; Scientific Computing; Beräkningsvetenskap;

   Sammanfattning : Boundary shape optimization is a technique to search for an optimal shape by modifying the boundary of a device with a pre-specified topology. We consider boundary shape optimization of acoustic horns in loudspeakers and brass wind instruments. LÄS MER

5. 34. Waveguide Finite Elements Applied on a Car Tyre

   Författare :Carl-Magnus Nilsson; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; wave equation; wave solution; waveguide; finite element; spectral finite element; tyre noise; tyre vibration; input power; shells; pre stress; fluid shell coupling; axi--symmetric;

   Sammanfattning : Structures acting as waveguides are quite common withexamples being, construction beams, fluid filled pipes, railsand extruded aluminium profiles. Curved structures like cartyres and pipe-bends may also be considered as waveguides. Wavesolutions in such structures may be found by a method calledthe Waveguide Finite Element Method or WFEM. LÄS MER

7. 35. Alternatives for Finite Element Analysis of Blade Forging

   Författare :Behzad Soltani; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; residual stresses; blade forging; flow approach; metal forming; quasistatic implicit; dynamic explicit; forging; solid approach; finite element method; closed die forging;

   Sammanfattning : This thesis is a theoretical and numerical study of the weaknesses and capabilities of alternative finite element procedures for simulation of the blade forging problem and also an analysis of the practical aspects of that process. An overview is presented of the finite element method for non-linear problems with elastoplastic constitutive relations, focusing on quasistatic implicit and dynamic explicit approaches. LÄS MER