Search for dissertations about: "Harmonic perturbations"

Showing result 1 - 5 of 9 swedish dissertations containing the words Harmonic perturbations.

2. 1. The Effect of Different Perturbations on the Stability Analysis of Light Water Reactors

   Author : Victor Dykin; Chalmers tekniska högskola; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; BWR and PWR stability; stability indicators; propagating density perturbation; autocorrelation function; density wave oscillations; decay ratio; non-white driving force; damped harmonic oscillator; reduced order models; Green s function technique;

   Abstract : Neutron noise analysis techniques are studied and developed, with primary useof determining the stability of Boiling Water Reactors (BWRs). In particular, the role ofa specific perturbation prevailing in Light Water Reactors, the propagating densityperturbation, in the stability of BWRs and on the noise field of LWRs in general, isinvestigated by considering three topics. READ MORE

4. 2. Tearing mode dynamics in the presence of resonant magnetic perturbations

   Author : Richard Fridström; Per Brunsell; Marco Cecconello; KTH; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Tearing mode; plasma; fusion; reversed-field pinch; RFP; magnetic; confinement; resonant; perturbation; magnetohydrodynamics; MHD; EXTRAP T2R; Madison Symmetic Torus; Fysik; Physics;

   Abstract : Magnetically confined fusion (MCF) plasmas are typically subject to several unstable modes. The growth of one mode can limit the plasma energy confinement and might cause a termination of the plasma. Externally applied resonant magnetic perturbations (RMPs) are used to control and to mitigate some of the unstable modes. READ MORE

5. 3. Cosmoparticle Physics and String Theory

   Author : Stefan Sjörs; Marcus Berg; Joseph Conlon; Stockholms universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Supersymmetry; dark matter; cosmology; inflation; modifications of gravity; string theory; flux compactifications; perturbative string theory; teoretisk fysik; Theoretical Physics;

   Abstract : This thesis deals with phenomenological and theoretical aspects of cosmoparticle physics and string theory. There are many open questions in these topics. In connection with cosmology we would like to understand the detailed properties of dark matter, dark energy, generation of primordial perturbations, etc. READ MORE

6. 4. Runaway electrons and Alfvén eigenmodes in tokamaks

   Author : Håkan Smith; Chalmers tekniska högskola; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; two-way diffusion equation; compressional Alfvén eigenmode; fusion plasma physics; tokamak disruption; runaway electron; Alfvén cascade;

   Abstract : Runaway electrons can be generated as a consequence of the rapid thermal quench of the plasma in a tokamak disruption. If the time scale of this cooling is short compared to the collision time in the tail of the electron velocity distribution, incomplete thermalisation of this tail leads to a burst of runaway production. READ MORE

7. 5. Aspects of Wave Interaction in Nonlinear Media

   Author : Björn Hall; Chalmers tekniska högskola; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; nonlinear Schrödinger equation; incoherent solitons; partial incoherence; nonlinear wave interaction; Gross-Pitaevskii equation; modulational instability; collective dynamics; Wigner transform; nonlinear guided waves; Bose-Einstein condensation;

   Abstract : Selected aspects of various types of nonlinear wave interaction are investigated. These aspects are studied in terms of models described by Nonlinear Schrödinger equations, mainly analytically and numerically, but also experimentally. READ MORE