Sökning: "nonlocal"

Visar resultat 1 - 5 av 36 avhandlingar innehållade ordet nonlocal.

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. Plasticity and Damage Mechanics for Modeling Concrete Failure

   Författare :Peter Grassl; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; nonlocal; concrete; localization; plasticity; damage;

   Sammanfattning : Concrete structures exhibit strongly non-linear and complex mechanical behavior. Hence, they are nowadays often analyzed by means of the finite element method, whereby a realistic description of the material behavior is decisive for the validity of the results. LÄS MER

4. 3. Steady waves in local and nonlocal models for water waves

   Författare :Tien Truong; Matematik (naturvetenskapliga fakulteten); []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; The steady Euler equations; the Whitham equation; solitary waves; highest waves; periodic waves; transverse dynamics; The steady Euler equations; the Whitham equation; solitary waves; highest waves; periodic waves; transverse dynamics;

   Sammanfattning : We study the steady Euler equations for inviscid, incompressible, and irrotational water waves of constant density. The thesis consists of three papers. The first paper approaches the Euler equations through a famous nonlocal model equation for gravity waves, namely the Whitham equation. LÄS MER

5. 4. Modelling of fracture toughness using peridynamics : A Study of J-integral, essential work and homogenisation

   Författare :Christer Stenström; Pär Jonsén; Kjell Eriksson; Ugo Galvanetto; Luleå tekniska universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Peridynamics; J-integral; Essential work of fracture; Nonlocal methods; Meshless; Meshfree; Fracture; Crack tip; Exact analytical; Center cracked tension; Double edge notched tensile; fracture toughness; Peridynamik; Brottmekanik; Sprickspets; Brottseghet; Spänningsintensitet; Hållfasthetslära; Solid Mechanics;

   Sammanfattning : Fracture toughness is one of the most important properties of a material. Being able toaccurately estimate the energy that goes into forming new crack surfaces is essential for the development of new materials, quality assurance, structural monitoring and failure analysis. LÄS MER

7. 5. Urban Change Detection Using Multitemporal SAR Images

   Författare :Osama Yousif; Yifang Ban; Lorenzo Bruzzone; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Change detection; High resolution; Image denoising; Kittler-Illingworth; MAP-MRF; Multitemporal SAR images; Nonlocal means; Object-based; Otsu; Outlier detection; Remote sensing; SAR speckle; Urban; Geodesy and Geoinformatics; Geodesi och geoinformatik;

   Sammanfattning : Multitemporal SAR images have been increasingly used for the detection of different types of environmental changes. The detection of urban changes using SAR images is complicated due to the complex mixture of the urban environment and the special characteristics of SAR images, for example, the existence of speckle. LÄS MER