Sökning: "tracer"

Visar resultat 1 - 5 av 339 avhandlingar innehållade ordet tracer.

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

    Författare :Johan Arvelius; Umeå universitet; []
    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; Space physics; Rymdfysik;

    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

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

    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. Iodine Isotopes (129I and 127I) in the Baltic Sea   : Tracer applications & environmental impact

    Författare :Peng Yi; Ala Aldahan; Glen Snyder; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; radioactive 129I; stable 127I; AMS; iodine species; nuclear reprocessing facilities; tracers; Baltic Sea; circulation; water exchange; environmental impact;

    Sammanfattning : 129I is a radioactive isotope (T1/2= 15.7 million years) produced through natural and anthropogenic pathways, but the anthropogenic production is presently dominating the Earth’s surface environments. LÄS MER

  5. 4. Hydrological Transport in Shallow Catchments: : tracer discharge, travel time and water age

    Författare :Sofie Safeyeh Soltani; Vladimir Cvetkovic; Bijan Dargahi; Jan Olof Selroos; Andrea Rinaldo; KTH; []
    Nyckelord :Hydrological transport; travel time; water age; tracer discharge; Lagrangian pathway approach; pathway lengths; numerical modeling; Land and Water Resources Engineering; Mark- och vattenteknik;

    Sammanfattning : This focuses on hydrological transport in shallow catchments with topography-driven flow paths. The thesis gives new insight to kinematic pathway models for estimation of tracer discharge at the catchment outlet. LÄS MER

  7. 5. 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