Sökning: "Greens function"

Visar resultat 1 - 5 av 69 avhandlingar innehållade orden Greens function.

  1. 1. Periodized Thermal Greens Functions and Applications

    Författare :Andro Sabashvili; Göteborgs universitet; Göteborgs universitet; Gothenburg University; []
    Nyckelord :condensed matter physics; Greens function; graphene; DMFT; RPA; GW;

    Sammanfattning : This work describes a new formalism for Fermionic thermal Greens functions that are discretized in imaginary time. The discretization makes the thermal Greens function periodic in imaginary (Matsubara) frequency space and requires a generalisation of the Dyson equation and Luttinger-Ward-Baym-Kadanoff functional. LÄS MER

  2. 2. Development of a Numerical Tool for Estimating the Neutron Noise in Nuclear Reactors

    Författare :Viktor Larsson; Chalmers University of Technology; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; neutron noise; P1 theory; Analytical Green’s function; Analytical Nodal Method; P1 theory; Finite Difference Method; Green’s function; diffusion theory; diffusion theory;

    Sammanfattning : The neutron noise, i.e. the time-variations of the neutron flux around its meanvalue, can be used for obtaining important safety parameters in a nuclear reactor,e.g. LÄS MER

  3. 3. Power Reactor Noise Studies and Applications

    Författare :Vasiliy Arzhanov; Chalmers University of Technology; []
    Nyckelord :power spectra; control rod vibrations; Green s function; nesting hypothesis; adjoint function; fluctuating boundary; noise diagnostics; Accelerator Driven System; localisation algorithm; point reactor and adiabatic approximation;

    Sammanfattning : The present thesis deals with the neutron noise arising in power reactor systems. Generally, it can be divided into two major parts: first, neutron noise diagnostics, or more specifically, novel methods and algorithms to monitor nuclear industrial reactors; and second, contributions to neutron noise theory as applied to power reactor systems. LÄS MER

  4. 4. Model Vertices Beyond the GW Approximation

    Författare :Mikael Hindgren; Matematisk fysik; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Matematisk och allmän teoretisk fysik; thermodynamics; statistical physics; gravitation; GW approximation; Electron self energy; Green s function; consistency; local-field corrections; vertex function; conserving approximations; variational energies; Mathematical and general theoretical physics; classical mechanics; relativity; quantum mechanics; klassisk mekanik; kvantmekanik; relativitet; statistisk fysik; termodynamik; Fysicumarkivet A:1997:Hindgren;

    Sammanfattning : We study the effects of local vertex corrections to the self energy of the electron gas. We find that a vertex derived from time-dependent density-functional theory can give accurate self energies without including the explicit time dependence of the exchange-correlation potential provided, however, that a proper decay at large momentum transfer (large q) is built into the vertex function. LÄS MER

  5. 5. 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; []

    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