Sökning: "external field"

Visar resultat 6 - 10 av 539 avhandlingar innehållade orden external field.

1. 6. Some Aspects of Non-Perturbative Quantum Field Theory

   Författare :Joakim Hallin; Chalmers tekniska högskola; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Yang-Mills; QED; pair production; density matrix; external field; Schwinger model; gauge invariant; functional representation;

   Sammanfattning : The aim of this thesis is to describe some different ways in which non-perturbative methods enter in quantum field theory. In the thesis such methods enter in 1+1-dimensional theories: various Yang-Mills theories and electrodynamics. It also enters when treating charged bosons or fermions interacting with an external, classical field. LÄS MER

3. 7. QED with external fields : vacuum effects and thermodynamics

   Författare :Per Liljenberg; Chalmers tekniska högskola; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; density; QED; vacuum magnetization; unstable vacuum; finite temperature; external field; boson stars; relativistic Bose gas;

   Sammanfattning : .... LÄS MER

4. 8. Objects and objectivity : Alternatives to mathematical realism

   Författare :Ebba Gullberg; Sten Lindström; John Cantwell; Umeå universitet; []
   Nyckelord :HUMANIORA; HUMANITIES; Philosophy of mathematics; mathematical realism; ontological realism; semantic realism; platonism; the semantic argument; the indispensability argument; the non-uniqueness problem; Benacerraf s dilemma; the irrelevance challenge; Field; Carnap; Balaguer; Yablo; the internal external distinction; fictionalism; Theoretical philosophy; Teoretisk filosofi; Theoretical Philosophy; teoretisk filosofi;

   Sammanfattning : This dissertation is centered around a set of apparently conflicting intuitions that we may have about mathematics. On the one hand, we are inclined to believe that the theorems of mathematics are true. LÄS MER

5. 9. Bird orientation: external cues and ecological factors

   Författare :Johan Bäckman; Evolutionär ekologi; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; tracking radar; Emlen funnel.; Animal ecology; Djurekologi; oscillatory orientation; roosting flight; scatter; concentration; heading; cue calibration; light dependent; magnetoreception; subcutaneous fat stores; body condition; energetics; geomagnetic field; visual cues; orientation; birds; migration;

   Sammanfattning : Birds are generally capable of accurate orientation. In this thesis I present studies about the external cues and the ecological factors that influences bird orientation. A multitude of environmental cues are used to select and maintain a proper direction. LÄS MER

7. 10. Experimental studies of tearing mode and resistive wall mode dynamics in the reversed field pinch configuration

   Författare :Jenny-Ann Malmberg; KTH; []
   Nyckelord :Nuclear fusion; reversed field pinch; resistive wall instabilities; wall locked modes; tearing modes; resistive shell modes; field errors; Extrap T2; Extrap T2R; TPE-RX;

   Sammanfattning : It is relatively straightforward to establish equilibrium inmagnetically confined plasmas, but the plasma is frequentlysucceptible to a variety of instabilities that are driven bythe free energy in the magnetic field or in the pressuregradient. These unstable modes exhibit effects that affect theparticle, momentum and heat confinement properties of theconfiguration. LÄS MER