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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Activation of Organically-Bound Tritium by Tritiated Water in Soil

Shkarupin, Aliaksei 03 July 2019 (has links)
The fate of tritium in the environment is a target of interest in many studies. However reported concentrations of organically bound tritium (OBT) in soil are not well understood. In this study, a supplementary non-biological process of soil OBT activation in the environment was explored. The vicinity of SRB Technologies (Pembroke, Ontario) was chosen as the sampling location because of a significant airborne tritium release prior to 2001 which resulted in groundwater contamination. Soil cores were extracted from the ground near the tritium-releasing facility stack in 2017 and split into 10 cm subsamples for HTO/OBT, total carbon and hydrogen, particle size, thermogravimetric, radiocarbon and 3He mass spectrometry analyses. Observed HTO profiles revealed elevated tritium concentrations still retained in the soil. The results indicated that clay bound tritium masks the OBT signal and cannot be easily distinguished. Multiple short-term sample rinses with tritium-free water have little effect on clay bound water removal. Therefore, clay bound tritium should to be addressed in any future research related to soil OBT.
2

Tritium Mobility in the Environment Using Deuterium as an Analogue

DeHay-Turner, Brett January 2016 (has links)
Tritium is a radioisotope of hydrogen and a component of emissions from the nuclear industry. It is also a radioisotope of concern for human and environmental health. The near future could see an increase in tritium production as experimental fusion reactors initiate first plasma. The greatest risk pathway is human ingestion of edible plants grown near sites of tritium emissions as they can acquire high levels of organically bound tritium (OBT). Recent studies at a tritium Beta-light facility in Pembroke, Ontario, Canada characterized by tritiated hydrogen gas (HT) emissions have identified high OBT:HTO ratios that are not consistent with current tritium transfer models. This suggests that there is an unidentified physical, chemical, or biological mechanism generating OBT in plant tissue. Laboratory experiments have been undertaken using deuterium gas (D2) as an analogue for atmospheric HT in controlled plant exposure experiments, and compared the observations with short-term exposures at the SRBT facility. While the deuterium results did not uncover a hidden pathway or enrichment mechanism, the SRBT exposures showed elevated tissue free water tritium (TFWT) in stems and leaves in the presence of atmospheric HT, and lacking HTO in both soils and surrounding air. This study proposes that hydrogenase activity in microbial communities hosted within the laminar boundary layer on the leaf surface, are responsible for HT oxidation to HTO that contributes directly to leaf waters used in photosynthesis.
3

Den personifierade marknadsföringens effekter på köpintentioner : En studie med fokus på medvetenheten om online behavioral advertising

Westerberg, Elin, Wuopio, Elin January 2018 (has links)
Utvecklingen av tekniken sker i snabb takt vilket gör att människors vetskap om OBA inte alltid hänger med, inte heller lagar och regler som ska skydda deras integritet. Därför är det intressant att undersöka hur effektiv marknadsföringstypen OBA är beroende av konsumenternas medvetenhet om fenomenet. Syftet är att analysera hur hög, respektive låg medvetenhet hos konsumenter om online behavioral advertising påverkar deras köpintentioner, med fokus på Generation Ys uppfattningar. Denna studie visar på samband mellan lägre medvetenhet om OBA och högre köpintentioner. Lägre medvetenhet om denna typ av marknadsföring förknippas även med en högre oro kring integriteten. / The development of technology takes place at a rapid pace, which means that people's knowledge of OBA does not always keep up, nor laws and regulations that supposed to protect their privacy. Therefore, it is interesting to investigate how effective online behavioral advertising is as a marketing strategy, based on consumers’ awareness of the phenomenon. The purpose is to analyze how a high and a low level of consumers’ awareness about OBA affects their purchase intentions, focusing on Generation Y’s perceptions.This paper reveals a connection between lower awareness of OBA and higher purchase intentions. Even a higher concern about integrity in the context is associated with lower awareness about this type of marketing.
4

Development of a Novel Method for Automotive On-board Transmitter EMC Immunity Testing / Utveckling av en Immunitetsmetod för Elektromagnetisk Kompatibilitetstestning vid Simulering av Strålningskälla i Fordon

Holm, Ludvig January 2023 (has links)
As the automotive industry advances through technology integration, components are designed to operate at increasingly higher frequencies. Consequently, there will be an increasing demand for automotive electromagnetic compatibility (EMC) testing. Testing and certification institutes, such as RISE Research Institutes of Sweden AB, thus face an urgent need to develop innovative solutions that can effectively address this growing demand. This master thesis work concerns one EMC test method in particular - the On-board Transmitter (OBT). This is a test which mainly serves to test the immunity of vehicles to electromagnetic disturbances originating from hand-held devices. The conventional test is performed in an anechoic chamber and the methodology requires a substantial amount of time. The intent with this work is thus to evaluate the potential of a novel OBT method where the concept of a reverberating chamber is applied inside the vehicle compartment. Initially, the conventional method was examined from two mock-ups of idealized cases, and it was observed that the electromagnetic field in the near-field region of the transmitter is highly erratic. It was also concluded that the test setup is particularly sensitive to the polarization of the transmitter. With these findings in mind, the accuracy of the conventional method was deemed questionable. Evaluation of the proposed Reverberating On-board Transmitter (ROBT) method proved that the electromagnetic environment inside the vehicle did not resemble a perfect reverberation chamber. Which was expected as the absorbing material such as seating and upholstery likely prevents a field distribution similar to that in a reverberation chamber. Still, the intent of the project was to find a test method superior to the conventional method and it can be stated that the ROBT method is an adequate option due to its capacity to expose the electronics to isotropic radiation. This was found from two measures which this thesis introduces: expected isotropicity eiso, a relative measure of the electric field components and DDoF, a quantification of the spatial distribution inside a reverberation chamber. / EMC VERifiering av Autonoma fordon i modväxlad kammare (EMCVERA)

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