Sökning: "diffusion"

Visar resultat 1 - 5 av 832 avhandlingar innehållade ordet diffusion.

1. 1. Toward first-principles understanding of carbonitride precipitation in steels

   Detta är en avhandling från Chalmers University of Technology

   Författare :Dan Fors; Chalmers tekniska högskola.; Chalmers University of Technology.; [2008]
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Steels; Coarsening; Precipitates; Electronic structure; Interfaces; Density functional theory; Diffusion; Dislocation network; Peierls-Nabarro model; Misfit;

   Sammanfattning : The most important and widely used group of metallic alloys is steels, which are alloys of the element iron together with carbon and usually other elements such as B, N, V, Nb and Cr. The strength in these alloys is closely connected to the distribution of point defects, precipitates and grain boundaries which effectively act as obstacles for dislocation migration. LÄS MER

3. 2. Diffusion of Radionuclides in Bentonite Clay : Laboratory and in sity Studies

   Detta är en avhandling från Stockholm : KTH

   Författare :Mats Jansson; KTH.; [2002]
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Bentonite; montmorillonite; cation; anion; diffusion; sorption; cobalt; caesium; strontium; iodide; pertechnetate; surface diffusion; in situ;

   Sammanfattning : This thesis deals with the diffusion of ions in compactedbentonite clay. Laboratory experiments were performed toexamine in detail different processes that affect thediffusion. To demonstrate that the results obtained from thelaboratory investigations are valid under in situ conditions,two different kinds of in situ experiments were performed. LÄS MER

4. 3. Theory of Hydrogen Quantum Diffusion

   Detta är en avhandling från Chalmers University of Technology

   Författare :Thomas Mattsson; Chalmers tekniska högskola.; Chalmers University of Technology.; [1997]
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; hydrogen; diffusion; nickel; quantum; transition state theory; path-integrals; first-principles calculations; isotope effect;

   Sammanfattning : Atomic hydrogen adsorbed on a metal surface is one of the simplest possible examples of chemisorption, yet it is very challenging. The adsorption and the very elementary process of surface diffusion, a single atomic jump, have been investigated theoretically using several methods. LÄS MER

5. 4. Investigation of Water Mobility using Diffusion-Sensitive MRI: The Role of q-Space Imaging, High b-Values and Diffusion Time

   Detta är en avhandling från Chalmers University of Technology

   Författare :Jimmy Lätt; Lunds universitet.; Lund University.; [2008]
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; kurtosis; MRI; high b-value; diffusion; diffusion time; NMR; q-space;

   Sammanfattning : Nuclear magnetic resonance (NMR) diffusometry provides important information about molecular motion on a microscopic scale. The advantage of NMR diffusometry is its ability to characterise microstructures non-invasively. This has made the method important not only in chemistry, biochemistry and materials science, but also in medicine. LÄS MER

7. 5. Diffusion MRI of Small Ischemic Brain Lesions: Technical aspects, clinical experiences and diagnostic criteria

   Detta är en avhandling från Department of Diagnostic Radiology, University Hospital, SE-221 85 Lund, Sweden

   Författare :Bo Geijer; Lunds universitet.; Lund University.; [2001]
   Nyckelord :MEDICIN; MEDICINE; Clinical physics; radiology; Metastasis; ADC; b; Infarct; MRI; Ischemia; Diffusion-Weighted; Diffusion; tomography; medical instrumentation; Klinisk fysiologi; radiologi; tomografi; medicinsk instrumentering;

   Sammanfattning : Purpose: To compare the visualization of small ischemic brain lesions using diffusion using diffusion-weighted (DW) MRI and conventional imaging, with special regard to diagnostic efficiency. Imaging features of lesions of different ages, diagnostic limitations and technical principles were also investigated. LÄS MER