Sökning: "Finite-difference time-domain method"

Visar resultat 1 - 5 av 48 avhandlingar innehållade orden Finite-difference time-domain method.

1. 1. Efficient time-domain modelling suitable for optimising thermoacoustic devices

   Författare :Stig Kleiven; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; finite-difference; thermoacoustics; time domain; optimisation; equivalent source method; active control;

   Sammanfattning : Thermoacoustic heat pumps use acoustic work to transfer heat from cold to hot temperatures. Such devices benefit from being environmentally friendly, robust and simple. However, in practice these devices have too low efficiency and power compared to their conventional counterparts. LÄS MER

3. 2. Thermoacoustic refrigerators: Time-domain modelling and experimental setup

   Författare :Stig Kleiven; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; finite-difference time-domain; refrigerator; thermoacoustics; equivalent source method;

   Sammanfattning : Thermoacoustic refrigerators use acoustic waves to transfer heat. Although their benefits compared with their vapour-compression counterparts are environmental friendliness, robustness and simplicity, they are currently still less efficient than traditional vapour-compression refrigerators. LÄS MER

4. 3. 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

5. 4. A hybrid finite element method for electromagnetics with applications in time-domain

   Författare :DAVID DEGERFELDT; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Nitsche s method; antenna arrays; NASA almond; edge elements; scattering; explicit-implicit time-stepping; Maxwell s equations; Finite Element Method; mass lumping; stability analysis; Finite-Differences Time-Domain; periodic structures; shape and material optimization;

   Sammanfattning : In this thesis, a new hybrid method that combines the Finite Element Method (FEM) with the Finite-Difference in Time-Domain (FDTD) method is presented. Tetrahedrons in the unstructured FEM region are connected directly to thehexahedrons in the structured FDTD region. LÄS MER

7. 5. Wave Propagation in Structural Elements - Direct and Inverse Problems in the Time Domain

   Författare :Peter Folkow; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; integro-differential equations; non-uniform beams; wave splitting; wave propagator; finite difference; Timoshenko beam; imbedding; Mindlin plate; inverse problem; viscoelastic damping; nonlinear rod; transient wave propagation; Green function;

   Sammanfattning : The subject of this thesis is direct and inverse wave propagation problems in structural elements. The considered structures are beams, plates and rods. The models for the beams and the plates are based on linear theory, while the rods are assumed to be nonlinear. The greater part of the work concerns the Timoshenko beam. LÄS MER