Global ETD Search

11	Modelling of fission product release from TRISO fuel during accident conditions : benchmark code comparison / Ramlakan A. Ramlakan, Alastair Justin January 2011 (has links) This document gives an overview of the proposed MSc study. The main goal of the study is to model the cases listed in the code benchmark study of the International Atomic Energy Agency CRP–6 fuel performance study (Verfondern & Lee, 2005). The platform that will be employed is the GETTER code (Keshaw & van der Merwe, 2006). GETTER was used at PBMR for the release calculations of metallic and some non–metallic long–lived fission products. GETTER calculates the transport of fission products from their point of fission to release from the fuel surface taking into account gas precursors and activation products. Results show that for certain experiments the codes correspond very well with the experimental data whilst in others there are orders of magnitude differences. It can be seen that very similar behaviour is observed in all codes. Improvements are needed in updating the strontium diffusion coefficient and in understanding, on a deeper level, the transport of silver in TRISO particles and how it deviates from simple diffusion models. / Thesis (M.Sc. Engineering Sciences (Nuclear Engineering))--North-West University, Potchefstroom Campus, 2012. Fission product release GETTER TRISO Benchmark Model CRP-6 International Atomic Energy Agency Diffusion
12	Pressure, Gas Ratio And Operation Voltage Optimization Of A Helium-neon Laser Bilgili, Hulusi Birol 01 January 2005 (has links) (PDF) Aim of this thesis is to investigate the optimum working parameters of a helium-neon laser. Partial pressure ratios, total pressures of the gases and voltage-current characteristics were studied. The analysis of the results includes the minor factors (impurity, volume, etc.) and their effects to main parameters (laser power, voltage, current). Tables, which were formed by measured optical parameters as wavelength and power, converted to graphs and from these graphs optimal working conditions for the laser are obtained.
13	Purification et caractérisations physico-chimiques et électriques de silicium d'origine métallurgique destiné à la conversion photovoltaïque Degoulange, Julien 12 December 2008 (has links) (PDF) L'élaboration de silicium de qualité solaire par une autre route que la voie chimique semble aujourd'hui prometteuse pour réduire les coûts et garantir l'approvisionnement en matériau de la filière photovoltaïque. Un plasma inductif (Ar+H2+O2) couplé à un brassage électromagnétique du silicium liquide permet d'extraire une impureté critique : le bore. La compréhension de la volatilisation du bore a été étudiée via des calculs thermodynamiques sous FACTSAGE ainsi que des analyses chimiques en ligne des gaz de sortie par ICP-OES. L'étude du procédé a été divisée en deux étapes. Le brassage électromagnétique a fait l'objet d'une étude numérique et expérimentale. La répartition des espèces réactives à la surface a été étudiée en remplaçant le silicium par du graphite afin d'obtenir une image spatiale de la répartition des espèces à la surface. L'optimisation du procédé a permis d'obtenir un silicium avec une teneur en bore acceptable. Les caractérisations chimiques et électriques du matériau purifié ont révélées une quantité trop élevée d'aluminium, d'oxygène et de phosphore. Toutefois le matériau produit est utilisable par l'industrie, le rendement cellule est supérieur à 14% sur la partie p du lingot. Silicium purification plasma thermique thermodynamique analyses chimiques effet getter
14	Design studies for stand off bomb detection Matthew, Christopher P. January 1900 (has links) Master of Science / Department of Mechanical and Nuclear Engineering / William L. Dunn / A prototype system for detecting explosives at standoff distances, using a signature based radiation scanning approach, is being developed at Kansas State University. The prototype will incorporate both a machine x-ray source and a machine neutron source to generate signatures from unknown samples of material. These signatures can be compared to templates measured or calculated from known explosive samples using a figure-of-merit. The machine neutron source uses the fusion of deuterium and tritium to create 14.1 MeV neutrons. Due to its radioactivity, the tritium must be sealed within the system. A new method of controlling the gas pressure with the DT generator was developed using a Zr-V-Fe getter supplied by a commercial firm. The shielding and collimation of the 14.1 MeV neutron source is accomplished using layers of steel, high-density polyethylene and borated high-density polyethylene. This thesis describes the development of the gas control method for the sealed neutron source, design studies for the shielding and collimation of the neutron source and modifications made to the building in which the prototype is being housed. Getter 14.1 MeV neutron source Bomb Explosive Detection Vacuum pressure control Engineering, Materials Science (0794) Engineering, Mechanical (0548) Engineering, Nuclear (0552)
15	Bleats from the north : Evaluation of osteological methods with support of archaeogenetics to distinguish between sheep and goats / Bräkanden från Norden : Utvärdering av osteologisk metod med stöd av arkeogenetik för att särskiljamellan får och getter Theorell, Hannes January 2014 (has links) This study is an extension of the author's previous thesis (Theorell 2013) and focus on the analysed tibia, the humerus and the proximal and distal part of the radius of sheep bones from Gotland and goat bones from City of Falun. Methods for bone elements assessed in this study are compiled and evaluated by Zeder and Lapham (2010). The bones were then geneticallyspecies identified and the results were compared. Seven of thirteen criteria for both sheep and goat reached 100% of correct identification.Best performing criteria were on humerus and distal radius for both sheep and goats. The results for the complete bone assessments divided for the species showed best performance ongoats. Worst performing bone is the tibia. High performing criteria were found on all thetypes of bones used in this study which can be used to distinguish between sheep and goats. / Föreliggande studie är en utökning av författarens tidigare magisteruppsats (Theorell 2013) och fokuserar på att analysera skenben, överarmsben samt proximal och distal del av strålbenet från fårben från Gotland och getben från Falun. Metoder för benslagen som används i denna studie har samlats och utvärderats av Zeder och Lapham (2010). Efter osteologisk analys har benen genetiskt artidentifierats och resultaten från bägge analyser har jämförts. Sju av tretton kriterier för både får och getter visade 100% korrekt bedömning. Kriterier med bäst resultat fanns på överarmsben och distalt på strålben. Sett till bedömning av komplett benslag skilt mellan får och getter visade att metoderna presterade bäst på getter. Sämst resultat uppvisades på skenbenet. Generellt uppvisade samtliga benslag kriterier som är möjliga att använda för att särskilja mellan får och getter. Sheep Ovis aries Goats Capra hircus Osteology Archaeogenetics Ancient DNA Gotland Falun Får Ovis aries Getter Capra hircus Osteologi Arkeogenetik Ancient DNA Gotland Falun
16	Kinetically-Controlled Nitridation of Titanium Alloys Barker, Samuel Paul 17 May 2010 (has links) No description available. Materials Science Metallurgy Ti-6Al-4V nitridation titanium nitrides case-hardening nitrogen in solid solution powder pack getter XRD XPS TEM XEDS EELS TiN twinned Ti2N nucleation kinetically-controlled
17	Enhanced adhesives for the encapsulation of flexible organic photovoltaic modules / Adhésifs améliorés pour l'encapsulation des modules organiques photovoltaïques flexibles Boldrighini, Patrick Mark 30 June 2015 (has links) La limitation de perméation des gaz aux bordes de l’encapsulation des photovoltaïques organiques flexibles a été adressée par l’identification des chemins de perméation du vapeur d’eau et par la formulation des nanocomposites adhésives. Une version modifiée du test de calcium optique a été développée pour identifier l’importance des chemins de perméation différents présent dans l’encapsulation des modules photovoltaïques organiques flexibles. Les nanoparticules des phyllosilicates et les nanoparticules des zéolithes ont été dispersées dedans les formulations des adhésifs différents incluant les adhésifs acryliques sensibles à pression et les adhésifs UV réticulables. Les propriétés mécaniques, optiques, et barrières de vapeur d’eau des nanocomposites ont été caractérisés en plus de leur photo-stabilité sous irradiation UV. Les nanocomposites ont été également utilisés pour encapsuler les cellules photovoltaïques organiques et la stabilité des dispositifs a été évaluer sous les conditions de vieillissement accélérés d’humidité et température. / In order to address the issue of lateral water and oxygen permeation through the sides of the encapsulation and into flexible organic photovoltaic (OPV) devices, the water vapor permeation pathways were identified and several adhesive nanocomposites formulated and tested to limit these pathways. To identify the relative importance of the various water vapor permeation pathways present in the encapsulation of flexible OPV devices, a modified version of the optical calcium test was developed. Passive nanoparticles (phyllosilicates) and active nanoparticles (zeolites) were both evaluated dispersed in UV curing acrylate adhesives and acrylic block copolymer pressure sensitive adhesives. The nanocomposites were characterized for their mechanical and optical properties as well as their water vapor permeation and UV photostability. The adhesives were also used to encapsulate OPV devices and tested in accelerated humidity aging. Adhésif Nanocomposite Getter Zéolithe Phyllosilicate Photovoltaïque Photovoltaïque organique Test de calcium Encapsulation flexible Photo-stabilité Photo-dégradation UV réticulable Adhésif sensible à pression Perméation d’eau Barrière des gaz Adhesive Nanocomposite Getter Zeolite Phyllosilicate Photovoltaic Organic photovoltaic OPV Calcium test Flexible encapsulation Photostability Photo-degradation UV cure Pressure sensitive adhesive Water vapor permeation Gas barrier WVTR

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