Sökning: "Greens functions"

Visar resultat 11 - 15 av 54 avhandlingar innehållade orden Greens functions.

1. 11. Time-Dependent Many-Body Perturbation Theory: Possibilities and Limitations

   Författare :Marc Puig von Friesen; Matematisk fysik; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Many-body perturbation theory; Correlation functions; Hubbard model; Non-equilibrium Green s functions; Fysicumarkivet A:2011:Puig von Friesen;

   Sammanfattning : This dissertation investigates the possibilities and limitations of time-dependent many-body perturbation theory by studying small Hubbard clusters for which the exact solution is available. The first part of the thesis is comprised of a short introduction to the concepts and methodologies used. LÄS MER

3. 12. Computations of Automorphic Functions on Fuchsian Groups

   Författare :Helen Avelin; Andreas Strömbergsson; Dennis Hejhal; Warwick Tucker; Michael Rubinstein; Uppsala universitet; []
   Nyckelord :Mathematics; 11F72; 11F03; 11F06; 11Y35; 11-04; 11Y16; 33F06; 34B27; 33F05; MATEMATIK;

   Sammanfattning : This thesis consists of four papers which all deal with computations of automorphic functions on cofinite Fuchsian groups. In the first paper we develop an algorithm for numerical computation of the Eisenstein series. We focus in particular on the computation of the poles of the Eisenstein series. LÄS MER

4. 13. Transmission line theory for cable modeling: a delay-rational model based on Green's functions

   Författare :Maria De Lauretis; Sven Nordebo; Luleå tekniska universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Industriell elektronik; Industrial Electronics;

   Sammanfattning : At present, induction motors are controlled via the so-called variable-frequency drives (VFD) that allow to control the speed for the motors. The purpose of this PhD thesis is to improve electromagnetic modeling techniques for the study of conducted electromagnetic emissions in variable-frequency drives, with the aim of enhancing their reliability in energy production plants. LÄS MER

5. 14. Multiconductor transmission lines wideband modeling : A delay-rational Green’s-function-based method

   Författare :Maria De Lauretis; Jonas Ekman; Giulio Antonini; Wil Schilders; Luleå tekniska universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Industriell elektronik; Industrial Electronics;

   Sammanfattning : The performance of variable-frequency drives (VFDs) commonly used in energy production plants can be severely affected by electromagnetic (EM) noise in the form of conducted disturbances.A VFD is composed of an inverter, a motor, and a connecting power cable. LÄS MER

7. 15. Molecular Alligator Clips: A Study of Metal-Molecule Contacts for Molecular Electronics

   Författare :Anton Grigoriev; Chalmers tekniska högskola; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; nonequilibrium Green s functions; single crystal surfaces; nanostructures; chemisorption; selenium; low index single crystal surface; density functional calculations; organic molecules; sulphur; nonequilibrium electron transport; gold;

   Sammanfattning : In this thesis we present a computational study of the elementary building blocks for molecular electronics, interconnected electronic devices with critical dimensions below 5 nm. Building electronic circuits on that scale requires stable connection between the various parts of the device and to the macroscopic metal electrodes, needed for power supply, support and integration with conventional electronics. LÄS MER