Sökning: "matematik metod"

Visar resultat 1 - 5 av 89 avhandlingar innehållade orden matematik metod.

1. 1. Causal Combinatorics : Edges of the Characteristic Imset Polytopes

   Författare :Petter Restadh; Svante Linusson; Liam Solus; James Cussens; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Matematik; Mathematics;

   Sammanfattning : Explaining data in a concise and efficient manner has become increasingly important in today's society. This thesis pertains to the problem of finding causal links within data, and how that can be done from a mathematical perspective. Using the framework of graphical models has several advantages, from interpretability to efficiency. LÄS MER

3. 2. Tame representations in Topological Data Analysis: decompositions, invariants and metrics

   Författare :Francesca Tombari; Wojciech Chachólski; Patrizio Frosini; Peter Bubenik; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; topological data analysis; tameness; decompositions; invariants; metrics; Matematik; Mathematics;

   Sammanfattning : This thesis is a compilation of results that can be framed within the field of applied topology. The starting point of our study is objects presenting a possibly complex intrinsic geometry. The main goal is then to simplify, without trivializing, the geometric information characterising these objects by choosing an appropriate representation. LÄS MER

4. 3. 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

5. 4. Parabolic equations with low regularity

   Författare :Magnus Fontes; Matematik LTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Matematik; Mathematics; Galerkin approximation.; low regularity; variational method; Hilbert transformation; fractional calculus; parabolic equations; quasilinear;

   Sammanfattning : In this work we study a variational method for treating parabolic equations that yields new results for non-linear equations with low regularity on source and boundary data. We treat mainly strongly parabolic quasilinear equations and systems in divergence form. LÄS MER

7. 5. Studies of vector tomography

   Författare :Kent Stråhlén; Matematik LTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Doppler tomography; Doppler Radon transform; local tomography; vectorial k-plane transform; vectorial Radon transform; k-plane transform; Radon transform; tomography; vector tomography; Mathematics; Matematik;

   Sammanfattning : The motivation to study the kind of problems appearing in this thesis has been ultrasound measurements of flows, from which velocity spectra along lines can be determined. These velocity spectra can mathematically be described by a new non-linear transform, here called the Doppler Spectral Transform (DST). LÄS MER