Sökning: "Spectral density"

Visar resultat 21 - 25 av 197 avhandlingar innehållade orden Spectral density.

  1. 21. Color Tuning for Perovskite Light-Emitting Diodes

    Författare :Hongling Yu; Feng Gao; Xiaoke Liu; Olle Inganäs; Fengling Zhang; Maksym V. Kovalenko; Linköpings universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Perovskite light-emitting diodes; Color tuning; Pure and mixed halide; Spectral stability; White emission;

    Sammanfattning : Metal halide perovskites (MHPs) are recognized as promising semiconductor materials for a variety of optical and electrical device applications due to their cost-effective and outstanding optoelectronic properties. As one of the most significant applications, perovskite light-emitting diodes (PeLEDs) hold promise for future lighting and display technologies, attributed to their high photoluminescence quantum yield (PLQY), high color purity, and tunable emission color. LÄS MER

  3. 22. Lineshape in Quantum Cascade Lasers - Temperature, Screening and Broadening

    Författare :Rikard Nelander; Matematisk fysik; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Quantum Cascade Lasers; quantum wells; spectral lineshape; Non-Equilibrium Green s Functions; screening; temperature dependence;

    Sammanfattning : This dissertation deals with the optical properties of Quantum Cascade Lasers (QCLs). Studies are performed using transport calculations employing the theory of Non-Equilibrium Green's Functions, and screening is studied within the Random Phase Approximation. Focus is put on the temperature dependent effects in THz QCLs. LÄS MER

  4. 23. Noise diagnostics of Stationary and Non-Stationary Reactor Processes

    Författare :Carl Sunde; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; core-barrel vibrations; break-frequency method; wavelet; decay ratio; detector tube impacting; two-phase flow; spectral analysis; noise diagnostics;

    Sammanfattning : This thesis concerns the application of noise diagnostics on different problems in the area of reactor physics involving both stationary and non-stationary core processes. Five different problems are treated, divided into three different parts. LÄS MER

  5. 24. Propagation of Chaos for Kac-like Particle Systems

    Författare :Dawan Mustafa; Göteborgs universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Master equations; chaotic densities; kinetic equations; propagation of chaos; Kac model; thermostatted master equation; Boltzmann equation; BGK equation; quenched process; uniform distribution; spectral gap; approximation process; kinetic equations;

    Sammanfattning : This thesis concerns various aspects of the Kac model. The Kac model is a Markov jump process for a particle system where the total kinetic energy of the system is conserved. This particle model is connected to a limiting equation, describing the evolution of a one-particle density, when the numbers of particles tends to infinity. LÄS MER

  7. 25. Regolith Properties of Mercury Derived from Observations and Modelling

    Författare :Johan Warell; Nick Thomas; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Astronomy; Mercury; Moon; imaging; photometry; spectroscopy; regolith; space weathering; light scattering; spectral modelling; Astronomi; Astronomy and astrophysics; Astronomi och astrofysik; astronomi; Astronomy;

    Sammanfattning : The properties of Mercury's regolith have been investigated at optical and near-infrared wavelengths with high-resolution imaging, photometric, and spectroscopic observations with the Swedish Vacuum Solar Telescope and the Nordic Optical Telescope. A new global optical map at a spatial resolution of 200 km shows that the well known (from Mariner 10) and poorly known hemispheres are indistinguishable with respect to the distribution, number density, and morphological parameters of bright albedo features. LÄS MER