Sökning: "Tracer"

Visar resultat 1 - 5 av 120 avhandlingar innehållade ordet Tracer.

  1. 1. Calibration and quality assessment of DESCARTES : grabsampler for stratospheric tracers

    Författare :Johan Arvelius; Umeå universitet.; [2005]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Adsorption; Balloon; Carboxen; CFC; Chloro-Fluoro Carbon; Grab sampling; Halocarbon; Molecular sieve; Stratospheric tracer; Tracer; Adsorption; Ballong; Carboxen; CFC; Halogeniserade kolväten; Klor-Flourkarbon; Spårgas; Stratosfärisk spårgas;

    Sammanfattning : DESCARTES is a light-weight, balloon-borne grab sampler for stratospheric long-lived tracers developed at the University of Cambridge. 33 flights have been performed with two versions of the instrument at northern latitudes by the DESCARTES team at the Swedish Institute of Space Physics (IRF) in Kiruna during the years 1997-2000. LÄS MER

  3. 2. Effect of Hyporheic Exchange on Conservative and Reactive Solute Transport in Streams : Model Assessments Based on Tracer Tests

    Detta är en avhandling från Uppsala : Acta Universitatis Upsaliensis

    Författare :Karin Jonsson; Uppsala universitet.; [2003]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Earth sciences; conservative; hyporheic exchange; model; reactive; retention; solute; sorption kinetics; stream transport; temporal moments; tracer experiment; Geovetenskap; sedimentologi; Sedimentology;

    Sammanfattning : Understanding of the processes affecting solute transport in flowing water is important for the possibility to predict the evolution with time of polluted stream systems. This thesis presents tracer experiment methodology and model developments for solute transport in streams, with special focus on retention processes and their effect on solute stream transport. LÄS MER

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

    Detta är en avhandling från Stockholm : KTH

    Författare :Kjartan Gudmundsson; KTH.; [2003]
    Nyckelord :TEKNIKVETENSKAP; TECHNOLOGY; tracer gas; water vapour permeability; diffusion; surface diffusion; isotopic analysis; deuterium; oxygen-18; fractionation; vapour barrier; transient numerical modelling of diffusion;

    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

  5. 4. Gas Mixing in a Circulating Fluidised Bed Boiler

    Detta är en avhandling från Chalmers University of Technology

    Författare :Johan Sternéus; Chalmers tekniska högskola.; Chalmers University of Technology.; [2001]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; TEKNIKVETENSKAP; TECHNOLOGY; fluidization; circulating fluidized bed; boiler; gas mixing; dispersion; tracer; turbulence; two-phase flow; scaling;

    Sammanfattning : The present thesis is a study on the gas-mixing behaviour in a circulating fluidised bed (CFB) boiler. The aim is to describe how gas is spread in different regions of a CFB furnace and to explain variations in the mixing rate under different operating conditions. LÄS MER

  7. 5. Imaging and Quantification of Brain Serotonergic Activity using PET

    Detta är en avhandling från Uppsala : Acta Universitatis Upsaliensis

    Författare :Pinelopi Lundquist; Uppsala universitet.; [2006]
    Nyckelord :Pharmacokinetics Pharmacotherapy; Brain serotonin; Neurotransmitter release; Neurotransmitter synthesis; Positron emission tomography; Tracer validation; Tracer modelling; Farmakokinetik Farmakoterapi;

    Sammanfattning : This thesis investigates the potential of using positron emission tomography (PET) to study the biosynthesis and release of serotonin (5HT) at the brain serotonergic neuron. As PET requires probe compounds with specific attributes to enable imaging and quantification of biological processes, emphasis was placed on the evaluation of these attributes. LÄS MER