Search for dissertations about: "spectral gap"

Showing result 16 - 20 of 46 swedish dissertations containing the words spectral gap.

  2. 16. Spectra and Dynamics of Excitations in Long-Range Correlated Structures

    Author : Lars Kroon; Rolf Riklund; Magnus Johansson; Jeroen Lamb; Linköpings universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; quasicrystals; deterministic aperiodic superlattices; Markov chains; electronic structure and diffusion; elastic vibrations; Fraunhofer diffraction; discrete solitons; phase transitions; Condensed matter physics; Kondenserade materiens fysik;

    Abstract : Vad karaktäriserar en kristall? Svaret på denna till synes enkla fråga blir kanske att det är en anordning av atomer uppradade i periodiska mönster. Så ordnade strukturer kan studeras genom att det uppträder så kallade Braggtoppar i röntgendiffraktionsmönstret. READ MORE

  4. 17. Impact of carrier localization on recombination in InGaN quantum wells with nonbasal crystallographic orientations

    Author : Ruslan Ivanov; Saulius Marcinkevičius; Nicolas Grandjean; KTH; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; InGaN; quantum well; semipolar; nonpolar; near-field microscopy; carrier localization; carrier transport; optical polarization; Fysik; Physics;

    Abstract : The modern InGaN technology demonstrates high efficiencies only in the blue spectral region and low current operation modes. The growth of InGaN quantum wells (QWs) on nonbasal crystallographic planes (NBP) has potential to deliver high-power blue and green light emitting diodes and lasers. READ MORE

  5. 18. Voronoi Constellations for Coherent Fiber-Optic Communication Systems

    Author : Shen Li; Chalmers tekniska högskola; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; coded modulation; constellation shaping; geometric shaping; forward error correction coding; lattices; Voronoi constellations.; multidimensional modulation formats; Achievable information rates; coherent fiber-optic communications;

    Abstract : The increasing demand for higher data rates is driving the adoption of high-spectral-efficiency (SE) transmission in communication systems. The well-known 1. READ MORE

  6. 19. Development and Application of Laser Diagnostics for Studies of Phenomena Related to IC Engine Combustion

    Author : Greger Juhlin; Förbränningsfysik; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Motors and propulsion systems; framdrivningssystem; Motorer; Laser technology; Laserteknik; Fysicumarkivet A:2003:Juhlin;

    Abstract : Various laser diagnostic techniques have been developed and demonstrated for engine, or engine-related measurements. The experimental work is presented in Chapter 3 and in Papers I-VII. In Chapter 3, imaging of soot in a running compression-ignition (CI) is described. READ MORE

  7. 20. Angle-resolved photoemission study of unconventional cuprate superconductors

    Author : Qinda Guo; Oscar Tjernberg; Andrea Damascelli; KTH; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Unconventional superconductivity; cuprate; high harmonic generation; narrow bandwidth light source; spherical grating based monochromator; time- and angle-resolved photoemission spectroscopy; Okonventionell supraledning; kuprat; hög övertonsgenerering; ljuskälla med smal bandbredd; sfäriskt gitterbaserad monokromator; tids- och vinkelupplöst fotoemissionsspektroskopi;

    Abstract : Understanding unconventional superconductivity remains one of the most important unsolved problems in physics. A particularly noteworthy case is the copper-based high-temperature superconductor, which stands out due to its remarkably high transition temperature and relatively simple structure. READ MORE