Sökning: "elliptical"

Visar resultat 6 - 10 av 66 avhandlingar innehållade ordet elliptical.

1. 6. Dissipative formation of galaxies in hierarchical cosmology

   Författare :John Hultman; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Astronomy; merical methods; hydrodynamics; galaxies: formation; galaxies: elliptical; galaxies: structure; star formation; Astronomi; Astronomy and astrophysics; Astronomi och astrofysik; Theoretical Astrophysics; teoretisk astrofysik;

   Sammanfattning : A description and detailed tests of a numerical code for simulations of galaxy formation is presented. The dynamics is followed with fully adaptive and Lagrangian Smooth Particle Hydrodynamics (SPH) combined with a gravitational tree method. The severe numerical problem of sub-resolution clustering is solved by merging of gas particles. LÄS MER

3. 7. Computational Modelling for Cavitation and Tip Vortex Flows

   Författare :Abolfazl Asnaghi; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Cavitation; SST k − ω; OpenFOAM; Propeller; LES; Numerical simulation; Cur- vature correction; Elliptical foil; Inception; Twisted Delft foil;

   Sammanfattning : Cavitation often brings negative effects, such as performance degradation, noise, vibration, and material damage, to marine propulsion systems, but for optimum performance, cavitation is almost inevitable. Therefore, it is necessary to better understand cavitation in order to maximize the performance without encounter- ing severe problems. LÄS MER

4. 8. Mechanisms of Blister Formation on Concrete Bridge Decks with Waterprooving Asphalt Pavement Systems

   Författare :Biruk Wobeshet Hailesilassie; Björn Birgisson; Lars-Olof Nilsson; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; blister growth; PBM waterproofing membrane; orthotropic material; biaxial test; peeling test; elliptical blister growth;

   Sammanfattning : Bridge decks are commonly subjected to harsh environmental conditions that often lead to serious corrosion problems triggered by blisters under the hot mix asphalt bridge deck surfacing and secretly evolving during weather exposure until damage is often detected too late. Blisters may form under both the waterproofing dense mastic asphalt layer or under the waterproofing membrane which is often applied as additional water protection under the mastic asphalt (MA). LÄS MER

5. 9. Design and Analysis of the Medium-β Elliptical Cavities for the European Spallation Source Accelerator

   Författare :Gabriele Costanza; Institutionen för elektro- och informationsteknik; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY;

   Sammanfattning : This thesis is dedicated to the design and analysis of superconductingelliptical cavities. Elliptical cavities play a central role in modern particle ac-celerators due to their high efficiency. After an introduction to the EuropeanSpallation Source project, the thesis goes through the design of the medium-βcavity. LÄS MER

7. 10. 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