Sökning: "impact excitation"

Visar resultat 21 - 25 av 76 avhandlingar innehållade orden impact excitation.

  1. 21. Atomic Processes in Stellar Atmospheres : Inelastic Collisions and Effects on Late-type Spectra

    Författare :Yeisson Fabian Martinez Osorio; Paul Barklem; Karin Lind; Nikolai Piskunov; Carlos Allende Prieto; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Spectral line: formation; atomic data; stellar abundances.; Fysik med inriktning mot astrofysik; Physics with specialization in Astrophysics;

    Sammanfattning : Chemical abundances as measured from stellar spectral lines are often subject to uncertainties due to lack of accurate data for inelastic collisions, which is needed for non-local thermodynamic equilibrium (non-LTE) modelling. For cool stars, understanding of collision processes with electrons and hydrogen atoms is required to achieve high precision measurements. LÄS MER

  3. 22. Modelling of wheel/rail interaction considering roughness and discrete irregularities

    Författare :Astrid Pieringer; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; roughness; non-Hertzian contact; railway noise; vertical wheel rail interaction; time domain; discrete irregularities;

    Sammanfattning : The interaction between wheel and rail is the predominant source of noise emission from railway operations in a wide range of conventional speeds. On the one hand, this wheel/rail noise concerns rolling noise and impact noise caused by the vertical interaction excited by roughness and discrete irregularities of the wheel/rail running surfaces, respectively. LÄS MER

  4. 23. Non-Linear Vibration and Dynamic Fracture Mechanics of Bridge Cables

    Författare :Armando Leon; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Cable Vibrations; Non-Linear Vibration; Dynamic Fracture Mechanics; Cable-Stayed Bridges; Dynamic Stress Intensity Factor;

    Sammanfattning : In the present work, the non-linear vibrations and the corresponding dynamic fracture mechanics of cables of cable-stayed bridges are studied. The cables are among the most critical components in cable-stayed bridges and there are different damage sources such as corrosion, vibration, fatigue and fretting fatigue that can significantly affect them, thereby reducing the cable’s service life and even producing their failure. LÄS MER

  5. 24. Analysis and Control Aspects of a PMSynRel Drive in a Hybrid Electric Vehicle Application

    Författare :Shuang Zhao; Chandur Sadarangani; Zi-Qiang Zhu; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Active damping control; electric drive; electric vehicle; hybrid electric vehicle; integrated charger; permanent-magnet assisted synchronous reluctance machine; position estimation; sensorless control;

    Sammanfattning : This thesis deals withmodeling and control of an electric drive equipped with a permanentmagnet assisted synchronous reluctance (PMSynRel) machine for a plug-in hybrid electric vehicle application.In the first part of the thesis, a special use of the PMSynRel machine in consideration, known as an integrated charger concept, is investigated. LÄS MER

  7. 25. Automated Photoluminescence Experimentation for Understanding Dynamic Metal-Halide Perovskite Semiconductors

    Författare :Alexander Kiligaridis; Kemisk fysik; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Photoluminescence; Perovskites; Semiconductor; Spectroscopy; Microscopy;

    Sammanfattning : Metal halide perovskites have garnered significant attention for their remarkable optoelectronic properties and unique photophysical characteristics. Combined with low cost for fabrication, this new class of materials is among the most promising candidates within next generation photovoltaic technologies. LÄS MER