Sökning: "approximation theory"

Visar resultat 1 - 5 av 128 uppsatser innehållade orden approximation theory.

  1. 1. Quantum Optical Description of High-order Harmonic Generation

    Master-uppsats, Lunds universitet/Atomfysik; Lunds universitet/Fysiska institutionen

    Författare :Isabel Moreno; [2024]
    Nyckelord :Physics and Astronomy;

    Sammanfattning : High-order Harmonic Generation (HHG) is a highly non-linear process in which an atom interacts with a strong laser field. The laser field lowers the atomic potential barrier allowing bound electrons to escape into the continuum through tunnel ionization, propagate, and, with some probability, recombine with the parent ion. LÄS MER

  3. 2. Effects of Ultrafast Ionization in X-ray Coherent Diffraction Imaging

    Master-uppsats, KTH/Kemi

    Författare :Arezu Sehati; [2023]
    Nyckelord :Coherent Diffraction Imaging; X-ray Free Electron Lasers; Refractive index; Core-shell nanoclusters; Rare-gas ionization; Koherent Diffraktionsavbildning; Röntgenfrielektronlaser; Brytningsindex; Core-shell-nanokluster; Ädelgasjonisering;

    Sammanfattning : Koherent Diffraktionsavbildning med en intensiv röntgenpuls från en Frielektronlaser har möjliggjort strukturbestämning av isolerade nanopartiklar som inte går att studera med hjälp av konventionella metoder, så som elektronmikroskopi. En mycket kort pulslängd tillsammans med spridningssignalens beroende av objektets elektroniska struktur medför också möjligheten att studera inducerad ultrasnabb dynamik med denna teknik. LÄS MER

  4. 3. Ray-Tracing Modeling of Grating Lobe Level Reduction by Using a Dielectric Dome Antenna

    Master-uppsats, KTH/Skolan för elektroteknik och datavetenskap (EECS)

    Författare :Lukas Jonasson; [2023]
    Nyckelord :Array antenna; Dielectric dome; Ray-Tracing; Grating lobe; Particle Swarm optimization; Gruppantenn; Dielektrisk kupol; Strålspårning; Gallerlob; Particle Swarm optimering;

    Sammanfattning : With the newly deployed fifth-generation telecommunications system and upcoming sixth-generation, high-gain antennas with hemispherical scanning capabilities are of high interest. Phased array antennas allow for fast scanning capabilities with electronic beam-steering. LÄS MER

  5. 4. First principles investigation of the thermal conductivity of Zr, ZrC, and ZrN

    Master-uppsats, KTH/Fysik

    Författare :Daniel Karlsson; [2023]
    Nyckelord :Electron-phonon interaction; Density functional theory; Boltzmann transport equation; first-principles; thermal conductivity; electrical resistivity; Abinit; Phono3py; Elektron-fononväxelverkan; täthetsfunktionalteori; Boltzmanns transportekvation; värmeledningsförmåga; elektrisk resistivitet; Abinit; Phono3py;

    Sammanfattning : The thermal conductivity and electrical resistivity of Zr, ZrC, and ZrN were calculated using first-principles density functional theory (DFT) and the Boltzmann transport equation. The electron-phonon scattering was modeled via the self-energy relaxation time approximation (SERTA), and the phonon-phonon scattering via the analogous single-mode relaxation time approximation (SMRTA). LÄS MER

  7. 5. A geometric approach to calculating the limit set of eigenvalues for banded Toeplitz matrices

    Master-uppsats, Lunds universitet/Matematik LTH

    Författare :Teodor Bucht; [2023]
    Nyckelord :Toeplitz matrices; Banded Toeplitz matrices; Limit set; Eigenvalues; Mathematics and Statistics;

    Sammanfattning : This thesis is about the limiting eigenvalue distribution of n × n Toeplitz matrices as n → ∞. The two classical questions we want to answer are: what is the limit set of the eigenvalues, and what is the limiting distribution of the eigenvalues. Our main result is a new approach to calculate the limit set Λ(b) for a Laurent polynomial b, i.e. LÄS MER