Search for dissertations about: "scattering time"

Showing result 1 - 5 of 476 swedish dissertations containing the words scattering time.

2. 1. Time Domain Boundary Element Methods for Acoustic Scattering

   Author : Georgios Natsiopoulos; Chalmers tekniska högskola; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; time domain; curved surface; room acoustics; boss model; boundary element method; regularization; transient; Hermite interpolation; hypersingular; acoustic scattering; vector potential;

   Abstract : In room acoustics, numerical computation of scattering phenomena is an important subject, since it is needed to accurately predict the influence of reflectors, the audience, balconies, etc, on the perceived acoustic quality of auditoria. The large physical volumes of auditoria and the wide frequency content of music and speech, together with the complicated geometries involved however, makes predictions in room acoustics a challenging task from a computational point of view. READ MORE

4. 2. Multi-Dimensional Quantitative Laser-based Diagnostics - Development and Practial Applications

   Author : Rikard Wellander; Förbränningsfysik; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Post injection; Structured illumination; Mie scattering; Dense sprays; Extinction coefficient; Signal attenuation; Laser extinction; Multiple scattering; Scattering measurements; Planar laser induced fluorescence; Time resolved; Imaging through turbulent media; Three-dimensional image acquisition; Diesel particulate filter regeneration; Wall impingent; Biodiesel; LII; Large-bore gas Engine; Pre-chamber ignition; Fysicumarkivet A:2014:Wellander;

   Abstract : Laser based optical diagnostic methods are routinely used in combustion research. Many of the more common approaches are based on illuminating a cross-section of the sample with a thin laser sheet. For example, by targeting an electronic transition in a molecule, its concentration within the plane illuminated by the laser sheet can be deduced. READ MORE

5. 3. Laser Diagnostics in Combustion - Elastic Scattering and Picosecond Laser-Induced Fluorescence

   Author : Frederik Ossler; Förbränningsfysik; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Spray; Picosecond laser; Streak camera; Time resolved; Fluorescence lifetimes; 3 – D flow imaging; 2 - D lifetime imaging; Pressure; Temperature; Hydrogen atoms; Oxygen atoms; 3-pentanone; Acetone; Lorenz-Mie theory; Aerosol; Fysicumarkivet A:1999:Ossler; Scattering; Fysik; Physics; Polycyclic aromatic hydrocarbons.;

   Abstract : Elastic scattering and the Lorenz-Mie (LM) theory in particular is used for the characterization of sub-micron- and micron-sized droplets of organic fuels in sprays and aerosols. Calculations on the Lorenz- Mie theory show that backward-sideward scattered visible radiation can be used for unambiguous detection of ensembles of homogeneous droplets of organic substances with diameters around 1 micrometer (size parameter between 2 and 6). READ MORE

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

   Author : DAVID DEGERFELDT; Chalmers tekniska högskola; []
   Keywords : 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;

   Abstract : 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. READ MORE

7. 5. Optimization for scattering and radiation problems based on a stable FEM-FDTD hybrid method

   Author : Tomas Halleröd; Chalmers tekniska högskola; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; finite-difference time-domain; finite element method; array antennas; electric and magnetic losses; pattern synthesis; shape and material optimization; explicit-implicit time-stepping; scattering;

   Abstract : In this thesis, a stable hybrid method combining the finite-elementmethod (FEM) and the finite-difference time-domain (FDTD) scheme forMaxwell's equations in two dimensions with both electric and magneticlosses is presented. It combines the flexibility of the FEM with theefficiency of the FDTD scheme. READ MORE