Sökning: "propagation constant"

Visar resultat 1 - 5 av 80 avhandlingar innehållade orden propagation constant.

1. 1. Propagation of some coherent and partially coherent laser beams

   Författare :Yangjian Cai; Sailing He; Franco Gori; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; : dark hollow beam; elliptical Gaussian beam; flat-topped beam; twisted anisotropic Gaussian Schell-model; partial coherent; propagation; paraxial optical system; Electrical engineering; electronics and photonics; Elektroteknik; elektronik och fotonik;

   Sammanfattning : In this thesis, we investigate the propagation of some coherent and partially coherent laser beams, including a dark hollow beam (DHB), an elliptical Gaussian beam (EGB), a flat-topped beam and a twisted anisotropic Gaussian Schell-model (TAGSM) beam, through a paraxial optical system or a turbulent atmosphere. Several theoretical models are proposed to describe a DHB of circular or non-circular symmetry. LÄS MER

3. 2. Electromagnetic dispersion modeling and analysis for HVDC power cables

   Författare :Stefan Gustafsson; Sven Nordebo; Martin Norgren; Linnéuniversitetet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; HVDC power cables; electromagnetic model; TDR measurement; sensitivity analysis; dispersion relation; propagation constant; low-frequency asymptotics;

   Sammanfattning : Derivation of an electromagnetic model, regarding the wave propagation in a very long (10 km or more) High Voltage Direct Current (HVDC) power cable, is the central part of this thesis. With an existing “perfect” electromagnetic model there are potentially a wide range of applications. LÄS MER

4. 3. New Methods for Reducing Ground-Borne Noise in Buildings above Railway Tunnels

   Författare :Osama A. B. Hassan; KTH; []
   Nyckelord :Ground-borne noise; railway noise; in-plane waves; wave-guides; scattering; propagation constant; input mobility; elastic stratum; dual integral equations;

   Sammanfattning : The rapid expansion of major cities in the west Europeancountries has accentuated the need to exploit every potentialsite for new establishments, e.g. areas over train tunnels andnear railway tracks in general. LÄS MER

5. 4. Modeling of Flame Propagation in Spark Ignition Engines

   Författare :Johan Wallesten; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES;

   Sammanfattning : Developers and manufacturers of gasoline engines are struggling to improve fuel economy and minimize negative environmental effects. Hence, lean burn and direct injection (DI), in particular stratified charge (SC), spark ignition (SI) engines are of special interest. LÄS MER

7. 5. Numerical modelling of sound propagation to closed urban courtyards

   Författare :Maarten Hornikx; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; courtyard; urban noise abatement schemes; pseudospectral; road traffic noise; equivalent sources method; scale model study; urban canyon;

   Sammanfattning : Because modern urban environments suffer from excessive levels of road traffic noise, access to closed courtyards is essential in order to offer urban sound environments of high quality with regard to health and perceived sound. To reach this quality, which is described by the quiet side definition, the 24-hour equivalent noise level should be below 45 dB(A). LÄS MER