Sökning: "tracer diffusion"

Visar resultat 1 - 5 av 24 avhandlingar innehållade orden tracer diffusion.

1. 1. Alternative methods for analysing moisture transport in buildings : Utilisation of tracer gas and natural stable isotopes

   Författare :Kjartan Gudmundsson; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; tracer gas; water vapour permeability; diffusion; surface diffusion; isotopic analysis; deuterium; oxygen-18; fractionation; vapour barrier; transient numerical modelling of diffusion; Building engineering; Byggnadsteknik;

   Sammanfattning : New methods, based on tracer gas measurements and isotopicanalysis can be used to evaluate the moisture properties ofbuilding materials and provide the means for forensic analysisof the origins and history of excessive water in buildings, theimmediate practical consequences of which will be the abilityto improve the moisture performance of constructions. It is shown, in theory and through measurements how thewater vapour permeability of porous building materials can witha good degree of accuracy be estimated with tracer gasmeasurements that provide an efficient alternative to the cupmethod. LÄS MER

3. 2. Lattice Boltzmann simulations of tracer diffusion in microswimmer suspensions

   Författare :Henrik Nordanger; Fysikalisk kemi; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Lattice Boltzmann; microswimmers; active matter; enhanced diffusion;

   Sammanfattning : Suspensions of microswimmers are a class of systems inherently out of equilibrium, due to the mechanical work continuously performed by a large number of active agents. Biological examples are plentiful, as many aquatic microorganisms have the ability to propel themselves. LÄS MER

4. 3. Nuclear magnetic resonance and microcirculation: The influence of pulsatile brain-tissue motion on measurements of intravoxel incoherent motion and assessment of haemodynamics using exo- and endogenous tracers

   Författare :Ronnie Wirestam; Lund Medicinsk strålningsfysik; []
   Nyckelord :MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; diagnostic radiology; cortical activation; diffusion; tumor; tumour; ischemic stroke; ischaemic stroke; tracer kinetics; bolus tracking; phase mapping; brain motion; intracranial dynamics; blood flow; haemodynamics; vascularity; MRS; perfusion; MRI; magnetic resonance; Clinical physics; radiology; tomography; medical instrumentation; Klinisk fysiologi; radiologi; tomografi; medicinsk instrumentering;

   Sammanfattning : In this project, the potential of magnetic resonance (MR) imaging and spectroscopy in studies of microcirculation and haemodynamics was evaluated. The spatial and temporal characteristics of human pulsatile brain-tissue movements in healthy individuals, relevant for the understanding of the cerebrospinal-fluid (CSF) circulation and the pathogenesis of hydrocephalus, were thoroughly investigated. LÄS MER

5. 4. Colloidal interactions and arrested dynamics of cellulose nanofibrils

   Författare :Malin Nordenström; Lars Wågberg; Torbjörn Pettersson; Lars Göran Ödberg; Andreas Fall; Wim Thielemans; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Cellulose nanofibrils; colloidal interactions; colloidal stability; arrested state; colloidal glass; colloidal gel; tracer diffusion; counterion; steric stabilization; redispersion; redispersion agent; Fiber- och polymervetenskap; Fibre and Polymer Science;

   Sammanfattning : Over the past decades, concerns for the environment have increased and efforts to achieve a sustainable society have intensified. One particular challenge is to replace fossil-based plastics with biodegradable materials produced from renewable resources. LÄS MER

7. 5. Water density impact on water flow and mass transport in rock fractures

   Författare :Helen Winberg-Wang; Longcheng Liu; Ivars Neretnieks; Andrew Frampton; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Tracer experiments; solute transport in fractured rock; advection-diffusion experiments; repositories; equivalent flowrate.; Spårämnesexperiment; ämnestransport i bergssprickor; advektion och diffusionsexperiment; slutförvar; ekvivalent flöde.;

   Sammanfattning : One way of taking care of spent nuclear fuel is to place it in a geological repository. In Sweden, a three-barrier system is planned. The system is based on encapsulating the fuel in copper canisters. These are surrounded by bentonite clay and buried under 500 m of bedrock. LÄS MER