Sökning: "Quantitative methods"

Visar resultat 31 - 35 av 2004 avhandlingar innehållade orden Quantitative methods.

1. 31. The Precipitationshed : Concepts, Methods, and Applications

   Författare :Patrick W. Keys; Line Gordon; Deliang Chen; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; water; atmosphere; precipitationshed; moisture recycling; variability; ecosystem services; social-ecological systems; Sustainability Science; vetenskap om hållbar utveckling;

   Sammanfattning : Human societies are reliant on the functioning of the hydrologic cycle. The atmospheric branch of this cycle, often referred to as moisture recycling in the context of land-to-land exchange, refers to water evaporating, traveling through the atmosphere, and falling out as precipitation. LÄS MER

3. 32. Separation of Water and Fat Signal in Magnetic Resonance Imaging : Advances in Methods Based on Chemical Shift

   Författare :Johan Berglund; Joel Kullberg; Lars Johansson; Håkan Ahlström; Zhi-Pei Liang; Uppsala universitet; []
   Nyckelord :LANTBRUKSVETENSKAPER; AGRICULTURAL SCIENCES; Magnetic resonance imaging; digital image reconstruction; chemical shift imaging; water and fat separation; Dixon method; fat suppression; quantitative MRI; whole-body MRI; fatty acid composition; fat unsaturation; triglycerides; adipose tissue; liver fat; T2* mapping; Radiology; Radiologi; Radiology; Radiologi;

   Sammanfattning : Magnetic resonance imaging (MRI) is one of the most important diagnostic tools of modern healthcare. The signal in medical MRI predominantly originates from water and fat molecules. LÄS MER

4. 33. Methodological aspects of quantitative cardiac molecular imaging

   Författare :Tanja Kero; Mark Lubberink; Håkan Ahlström; Elin Trägårdh; Uppsala universitet; []
   Nyckelord :PET; cardiac amyloidosis; 11C-PIB; retention index; standardized uptake value; PET-MR; MRI; myocardial blood flow; 15O-water; quantification; quantitative modeling;

   Sammanfattning : The objective of this research was to facilitate the use of quantitative cardiac molecular imaging by developing and validating methods and applications. More specifically:we determined the optimal tracer kinetic model for analysis of 11C-PIB and evaluated the performance of two simpler measures, retention index (RI) and standardized uptake value (SUV), in the quantification of cardiac 11C-PIB uptake in amyloidosis. LÄS MER

5. 34. Contributions to quantitative dynamic contrast-enhanced MRI

   Författare :Anders Garpebring; Mikael Karlsson; Ronnie Wirestam; Nils Östlund; Jón Hauksson; Steven Sourbron; Umeå universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Dynamic contrast-enhanced MRI; quantitative imaging; parameter estimation; uncertainty estimation; arterial input function; radiofysik; radiation physics;

   Sammanfattning : Background: Dynamic contrast-enhanced MRI (DCE-MRI) has the potential to produce images of physiological quantities such as blood flow, blood vessel volume fraction, and blood vessel permeability. Such information is highly valuable, e.g., in oncology. LÄS MER

7. 35. Adaptive Finite Element Methods for Compressible Two-Phase Flow

   Författare :Erik Burman; Göteborgs universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; adaptive finite element methods; two-phase flow; compressible flow; conservation laws; hyperbolic systems; a posteriori error estimates; streamline diffusion; stability analysis; quantitative error control; adaptive algorithms; quantitative error control;

   Sammanfattning : In this thesis we develop, apply and analyse adaptive finite element methods with error control for compressible flow problems, focusing in particular on two-phase flow. The adaptive algorithms, aiming at quantitative error control with efficient use of computational resources, are based on a posteriori error estimates, where the error is estimated in terms of the computed solution, the local mesh-size and certain stability factors. LÄS MER