Search for dissertations about: "Point scatterer"

Showing result 1 - 5 of 6 swedish dissertations containing the words Point scatterer.

2. 1. Numerical approximations of time domain boundary integral equation for wave propagation

   Author : Andreas Atle; KTH; []
   Keywords : MOT; Marching on in time; boundary integral equations;

   Abstract : Boundary integral equation techniques are useful in thenumerical simulation of scattering problems for wave equations.Their advantage over methods based on partial di.erentialequations comes from the lack of phase errors in the wavepropagation and from the fact that only the boundary of thescattering object needs to be discretized. READ MORE

4. 2. Crystallographic Aspects of Protein Phasing at Very Low Resolution

   Author : Klas Andersson; Jens Nyborg; Stockholms universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; strukturkemi; Structural Chemistry;

   Abstract : A protein crystallographic method for obtaining structure factor phases of low-order reflections is presented. It is based on four observations: 1) The electron density inside proteins is relatively smooth and uniform at low resolution. READ MORE

5. 3. Ultra-Wideband Wireless Channels - Estimation, Modeling and Material Characterization

   Author : Telmo Santos; Institutionen för elektro- och informationsteknik; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Ultra-wideband; channel modeling; channel parameter estimation; material characterization; microwave measurements;

   Abstract : This licentiate thesis is focused on the characterization of ultra-wideband wireless channels. The thesis presents results on ultra-wideband communications as well as on the ultra-wideband characterization of materials. The communications related work consisted in the measurement and modeling of outdoor scenarios envisioned for infostation systems. READ MORE

6. 4. Absorbed Dose Determination and Characteristics of Degraded Electron Beams: Application to Intraoperative Radiation Therapy

   Author : Peter Björk; Internmedicin - epidemiologi; []
   Keywords : MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; Clinical physics; radiology; tomography; medical instrumentation; Klinisk fysiologi; radiologi; tomografi; medicinsk instrumentering; absorbed dose distribution; output factor; stopping-power ratio; beam characteristics; Monte Carlo calculation; electron beam dosimetry; applicator system; radiation therapy; linear accelerator; intraoperative radiotherapy;

   Abstract : The aim of this work was to quantify limitations of and uncertainties in commonly used dosimetric techniques for relative absorbed dose determination in degraded electron beams, such as those encountered in intraoperative radiation therapy (IORT) and small-electron-field radiotherapy. Three different detector types were investigated with regard to measurements of output factors and relative absorbed dose distributions: (1) a parallel-plate ionization chamber, (2) a p-type silicon diode detector and (3) a diamond detector. READ MORE

7. 5. Transient waves in nonstationary media : with applications to lightning and nonlinear media

   Author : Ingegerd Åberg; Institutionen för elektro- och informationsteknik; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; lightning; Klein-Gordon; nonlinear; characteristics; wave splitting; imbedding; sources; propagators; Green functions; direct and inverse scattering; Nonstationary; transient; high-frequency switching; Kerr.; Technological sciences; Teknik;

   Abstract : Propagation of transient waves in nonstationary, inhomogeneous, dispersive, stratified media is considered. Waves originating from sources exterior to the scatterer as well as from internal sources are treated. Algorithms are developed and illustrated by computations of wave phenomena in stationary, nonstationary and weakly nonlinear media. READ MORE