Sökning: "Fourier integral operator"

Hittade 5 avhandlingar innehållade orden Fourier integral operator.

1. 1. Semi-classical approximations of Quantum Mechanical problems

   Författare :Ulf Karlsson; KTH; []
   Nyckelord :Schrödinger equation; semiclassical analysis; multi-well potential; potential wells; scale functions; spectral interval; Agmon metric; interaction matrix; hierarchical potential; Helmholtz operator; Fourier integral operator; global phase; hyperbolic;

   Sammanfattning : .... LÄS MER

3. 2. Orthogonal Polynomials, Operators and Commutation Relations

   Författare :John Musonda; Sergei Silvestrov; Sten Kaijser; Anatoliy Malyarenko; Natan Kruglyak; Irina Asekritova; Viktor Abramov; Mälardalens högskola; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Mathematics Applied Mathematics; matematik tillämpad matematik;

   Sammanfattning : Orthogonal polynomials, operators and commutation relations appear in many areas of mathematics, physics and engineering where they play a vital role. For instance, orthogonal functions in general are central to the development of Fourier series and wavelets which are essential to signal processing. LÄS MER

4. 3. Convergence Acceleration for Flow Problems

   Författare :Henrik Brandén; Sverker Holmgren; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Computational fluid dynamics; convergence acceleration; semicirculant preconditioning; fundamental solutions; Numerical Analysis; Numerisk analys;

   Sammanfattning : Convergence acceleration techniques for the iterative solution of system of equations arising in the discretisations of compressible flow problems governed by the steady state Euler or Navier-Stokes equations is considered. The system of PDE is discretised using a finite difference or finite volume method yielding a large sparse system of equations. LÄS MER

5. 4. Reordering in Noncommutative Algebras, Orthogonal Polynomials and Operators

   Författare :John Musonda; Sergei Silvestrov; Sten Kaijser; Johan Richter; Viktor Abramov; Mälardalens högskola; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Mathematics Applied Mathematics; matematik tillämpad matematik;

   Sammanfattning : The main object studied in this thesis is the multi-parametric family of unital associative complex algebras generated by the element $Q$ and the finite or infinite set $\{S_j\}_{j\in J}$ of elements satisfying the commutation relations $S_jQ=\sigma_j(Q)S_j$, where $\sigma_j$ is a polynomial for all $j\in J$. A concrete representation is given by the operators $Q_x(f)(x)=xf(x)$ and $\alpha_{\sigma_j}(f)(x)=f(\sigma_j(x))$ acting on polynomials or other suitable functions. LÄS MER

7. 5. Theoretical Investigation into Longitudinal Dispersion in Natural Rivers — A Scaling Dispersion Model

   Författare :Zhi-Qiang Deng; Avdelningen för Teknisk vattenresurslära; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; soil mechanics; Väg- och vattenbyggnadsteknik; Environmental technology; pollution control; Miljöteknik; kontroll av utsläpp; offshore technology; hydraulic engineering; Civil engineering; Scaling dispersion.; Parameter estimation; Numerical scheme; Dispersion coefficient; Natural river;

   Sammanfattning : Using a broad variety of scientific methods this dissertation systematically investigates the fundamental mechanisms underlying the dispersion processes in natural rivers and their mathematical descriptions in a geometrical framework. Emphasis is on the geometrical variations and irregularities of a natural river and their scales. LÄS MER