Sökning: "scattering operators"

Visar resultat 11 - 15 av 18 avhandlingar innehållade orden scattering operators.

1. 11. Inverse Problems in Tomography and Fast Methods for Singular Convolutions

   Författare :Fredrik Andersson; Matematik LTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Mathematics; Matematik; Unequally spaced FFT; Integral transforms; Singular integrals; Lippmann?Schwinger equation; Helmholtz equation; Inverse problems; Fast Gauss transform; Fast summation; Convolution; Radon transform; Tomography;

   Sammanfattning : There are two, partially interlaced, themes treated in this thesis; inverse problems of tomographic type and fast and accurate methods for the application of convolution operators. Regarding the first theme, the inverse problem of Doppler tomography is considered and the Doppler moment transform is introduced for that purpose. LÄS MER

3. 12. Topics in molecular mechanics

   Författare :Hanno Essén; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES;

   Sammanfattning : This report is a personal review of theoretical research concerning molecules. Here one finds some mathematical background from tensor calculus and Lie group theory. The most general transformations of the 3N-dimensional Laplacian, including transformations to group operators, are also presented. LÄS MER

4. 13. 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

5. 14. Inverse Problems for Graph Laplacians

   Författare :Marlena Nowaczyk; Matematik LTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Spectral theory; Laplace operator; Trace formula; Quantum graphs;

   Sammanfattning : This thesis is devoted to inverse spectral problems for Laplace operators on metric graphs, and it is based on the following papers: Paper I - P. Kurasov and M. Nowaczyk 2005 Inverse spectral problem for quantum graphs J. Phys. LÄS MER

7. 15. Inference on Dark Matter in Effective Field Theories : From XENON1T towards XENONnT: Chiral effective field theory analysis of nuclear recoils, single electrons and uncommon background modelling

   Författare :Vasile Cristian Antochi; Jan Conrad; Björn Penning; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Dark Matter; Direct Detection; Effective Field Theory; Chiral Effective Field Theory; Physics; fysik;

   Sammanfattning : Cosmological and astronomical observations show that most of the matter in the Universe is dark. This dissertation provides an overview of the dark matter evidence, and focuses on the particle dark matter hypothesis, describing possible particle candidates, concentrating on the Weakly Interactive Massive Particles (WIMPs). LÄS MER