Sökning: "finite difference methods"

Visar resultat 21 - 25 av 149 avhandlingar innehållade orden finite difference methods.

1. 21. Response of cable-stayed and suspension bridges to moving vehicles : Analysis methods and practical modeling techniques

   Författare :Raid Karoumi; KTH; []
   Nyckelord :cable-stayed bridge; suspension bridge; Great Belt suspension bridge; bridge moving loads; traffic-induced vibrations bridge-vehicle interaction; dynamic analysis; cable element; finite element analysis; finite diffrence method; tuned mass damper; TECHNOLOGY; TEKNIKVETENSKAP;

   Sammanfattning : This thesis presents a state-of-the-art-review and twodifferent approaches for solving the moving load problem ofcable-stayed and suspension bridges. The first approach uses a simplified analysis method tostudy the dynamic response of simple cable-stayed bridgemodels. LÄS MER

3. 22. Stable Numerical Methods with Boundary and Interface Treatment for Applications in Aerodynamics

   Författare :Sofia Eriksson; Jan Nordström; Gunilla Kreiss; Thomas Hagstrom; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; summation by parts; simultaneous approximation term; accuracy; stability; finite difference methods; Beräkningsvetenskap med inriktning mot numerisk analys; Scientific Computing with specialization in Numerical Analysis;

   Sammanfattning : In numerical simulations, problems stemming from aerodynamics pose many challenges for the method used. Some of these are addressed in this thesis, such as the fluid interacting with objects, the presence of shocks, and various types of boundary conditions. LÄS MER

4. 23. Perfectly Matched Layers and High Order Difference Methods for Wave Equations

   Författare :Kenneth Duru; Gunilla Kreiss; Jan Nordsröm; Ken Mattsson; Marcus Grote; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Elastic waves; Surface waves; Perfectly matched layers; High order difference methods; Stability; Summation-by-parts operators; Boundary treatments; Beräkningsvetenskap med inriktning mot numerisk analys; Scientific Computing with specialization in Numerical Analysis;

   Sammanfattning : The perfectly matched layer (PML) is a novel technique to simulate the absorption of waves in unbounded domains. The underlying equations are often a system of second order hyperbolic partial differential equations. In the numerical treatment, second order systems are often rewritten and solved as first order systems. LÄS MER

5. 24. Adaptive finite element/difference methods for time-dependent inverse scattering problems

   Författare :Larisa Beilina; Göteborgs universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES;

   Sammanfattning : In this thesis we develop adaptive hybrid finite element/difference methods for inverse time-domain acoustic and elastic scattering, where we seek to find the location and form of a (small) unknown object inside a large homogeneous body from measured wave-reflection data. We formulate the inverse problem as an optimal control problem, where we seek to reconstruct unknown material coefficients with best least squares wave fit to data. LÄS MER

7. 25. Hybrid Solvers for the Maxwell Equations in Time-Domain

   Författare :Fredrik Edelvik; Per Lötstedt; Jan Hesthaven; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Maxwell s equations; time-domain; finite volume methods; finite element methods; hybrid solver; dispersive materials; thin wires; Beräkningsvetenskap; Scientific Computing;

   Sammanfattning : The most commonly used method for the time-domain Maxwell equations is the Finite-Difference Time-Domain method (FDTD). This is an explicit, second-order accurate method, which is used on a staggered Cartesian grid. The main drawback with the FDTD method is its inability to accurately model curved objects and small geometrical features. LÄS MER