Sökning: "LDA"

Visar resultat 1 - 5 av 82 avhandlingar innehållade ordet LDA.

1. 1. Nonlocal Correlations in Density Functional Theory

   Författare :Henrik Rydberg; Chalmers tekniska högskola; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; bonding; GGA; adhesion; graphene; DFT; exchange; adsorption; LDA; first principles; polarization; vdW; determinants; correlation; graphite; surface states; van der Waals; density-functional theory; physisorption; nonlocal; functional;

   Sammanfattning : In Density Functional Theory, the widely used local and semilocal approximations to the exchange-correlation energy, the local density approximation (LDA) and the generalized gradient approximations (GGAs), lack a physical description of truly nonlocal correlation effects, which are absolutely essential for a proper description of soft matter. A scheme is proposed that provides a basis for systematic improvements beyond LDA and GGA, including correlations at intermediate and long range, giving rise to bonds of pure van der Waals type as well as more intricate, intermediate-range correlation bonds. LÄS MER

3. 2. Hydrodynamics and Complete Suspension in Axially Stirred Vessels

   Författare :Claes Sturesson; Chalmers tekniska högskola; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; axially stirred tank; particle force balances; complete suspension; turbulence modeling; turbulent boundary layer; LDA;

   Sammanfattning : Complete suspension of solid particles in stirred vessels has been subject to numerous investigationsin order to develop appropriate design criteria for solid/liquid suspensions. Previous work on this matter has often suffered from the lack of knowledge of fluid mechanics in the system and models based on overall flow characteristics have been proposed in the literature. LÄS MER

4. 3. Some Aspects of Gas Turbine Fuel Preparation and Turbomachinery Response to LCV Fuels

   Författare :Pontus Eriksson; Kraftverksteknik; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; PDA; LDA; PIV; atomization; spray; off-design; biogas; combustor; biofuel; turbine; Gas turbine; compressor;

   Sammanfattning : This thesis gives some background information on environmental issues as the scientific community at large currently sees it. It tries to relate the plethora of current combustion technologies which may be used in gas turbines to those issues. Some basic principles on combustion design are given. LÄS MER

5. 4. A Study of the Initial Mould Filling during Up-hill Ingot Casting

   Författare :Line Hallgren; Pär Jönsson; Anders Tilliander; Seppo Louhenkilpi; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; swirling flow; up-hill teeming; nozzle; casting; fluid flow; modelling; CFD; LDA; swirl; ingot casting; filling; red eye;

   Sammanfattning : The fluid flow in the mould during up-hill teeming is of great importance for the quality of the cast ingot and thereby the quality of the final steel products. At the early stage of the filling of an up-hill teeming mould, liquid steel flows with a high velocity from the runner into the mould. LÄS MER

7. 5. Effect of swirling blade on flow pattern in nozzle for up-hill teeming

   Författare :Line Hallgren; Pär Jönsson; Jonas Alexis; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; swirling flow; up-hill teeming; nozzle; casting; fluid flow; modelling; CFD; LDA.; Metallurgical process engineering; Metallurgisk processteknik;

   Sammanfattning : The fluid flow in the mold during up-hill teeming is of great importance for the quality of the cast ingot and therefore the quality of the final steel products. At the early stage of the filling of an up-hill teeming mold, liquid steel enters, with high velocity, from the runner into the mold and the turbulence on the meniscus could lead to entrainment of mold flux. LÄS MER