Sökning: "propagation"

Visar resultat 1 - 5 av 1103 avhandlingar innehållade ordet propagation.

  1. 1. Beam propagation

    Författare :Björn Hermansson; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Fysicumarkivet A:1989:Hermansson;

    Sammanfattning : [abstract missing].... LÄS MER

  2. 2. Cost Propagation - Numerical Propagation for Optimization Problems

    Författare :Birgit Grohe; Chalmers University of Technology; []
    Nyckelord :optimization; numerical propagation; Cost propagation;

    Sammanfattning : In this thesis, we investigate Cost Propagation,an approach to numerical propagation for optimization problems, where we combine ideas from both Constraint Programming and Combinatorial Optimization. We consider discrete optimization problems with binary variables that can be expressed in the model max_x sum_k g_k(x^k)where the terms g_k(x^k) are distinct arbitrary functions over subsets x^k of x. LÄS MER

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

    Författare :Yangjian Cai; Sailing He; Franco Gori; KTH; []
    Nyckelord :ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; : 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

  4. 4. 60 GHz Wireless Propagation Channels: Characterization, Modeling and Evaluation

    Författare :Carl Gustafson; Institutionen för elektro- och informationsteknik; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; 60 GHz; mm-wave; IEEE 802.11ad; IEEE802.15.3c; Channel measurements; Channel modeling; propagation; MIMO; Beamforming; Spatial Multiplexing;

    Sammanfattning : To be able to connect wirelessly to the internet is nowadays a part of everyday life and the number of wireless devices accessing wireless networks worldwide are increasing rapidly. However, with the increasing number of wireless devices and applications and the amount available bandwidth, spectrum shortage is an issue. LÄS MER

  5. 5. A Wave Expansion Method for Aeroacoustic Propagation

    Författare :Johan Hammar; Gunilla Efraimsson; Ciarán J. O'Reilly; Wim De Roeck; KTH; []
    Nyckelord :ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Sound propagation; Sound generation; Aeroacoustics; Aerodynamics; Computational fluid dynamics; Computational aeroacoustics; Numerical methods; Lighthill; Curle; Ffowcs Williams and Hawkings; Frequency-domain propagation; Wave expansion method.; Farkostteknik; Vehicle and Maritime Engineering;

    Sammanfattning : Although it is possible to directly solve an entire flow-acoustics problem in one computation, this approach remains prohibitively large in terms of the computational resource required for most practical applications. Aeroacoustic problems are therefore usually split into two parts; one consisting of the source computation and one of the source propagation. LÄS MER