<p>Fission is the most important nuclear reaction for society at large today due to its use in energy production. However, this has raised the problem of how to treat the long-lived radioactive waste from nuclear reactors. A radical solution would be to change the composition of the waste into stable or short-lived nuclides, which could be done through nuclear transmutation. Such a concept requires accelerator-driven systems to be designed, where those for transmutation are reactor hybrids. This thesis is a contribution to the knowledge base for developing transmutation systems, specifically with respect to the computational modeling of the underlying nuclear reactions, induced by the incident and secondary particles. Intermediate energy fission cross sections are one important type of such data. Moreover, they are essential for understanding the fission process itself and related nuclear interactions. </p><p>The experimental part of this work was performed at the neutron beam facility of the The Svedberg Laboratory in Uppsala. Fission cross sections of ²³⁸U, ²⁰⁹Bi, ^natPb, ²⁰⁸Pb, ¹⁹⁷Au, ^natW, and ¹⁸¹Ta were measured for neutrons in the range <i>E</i>_n = 30-160 MeV using thin-film breakdown counters for the fission fragment detection. A model was developed for the determination of the efficiency of such detectors. </p><p>A compilation of existing data on proton-induced fission cross sections for nuclei from ¹⁶⁵Ho to ²³⁹Pu was performed. The results, which constitute the main body of information in this field, were added to the worldwide EXFOR database. The dependences of the cross sections on incident energy and target nucleus were studied, which resulted in systematics that make it possible to give estimates for unmeasured nuclides. </p><p>Nucleon-induced fission cross sections were calculated using an extended version of the cascade exciton model. A comparison with the systematics and the experimental data obtained in the present work revealed significant discrepancies. A modification of the model was made that significantly improved the predictions. </p>

La validation des systèmes critiques réalistes nécessite d'être capable de modéliser et de vérifier formellement des données complexes, du parallélisme asynchrone, et du temps-réel simultanément. Des langages de haut-niveau, comme ceux qui héritent des fondations théoriques des algèbres de processus, ont une syntaxe concise et une grande expressivité pour représenter ces aspects. Cependant, ils disposent de peu d'outils logiciels permettant d'appliquer des algorithmes efficaces du model-checking. Néanmoins, de tels outils existent pour des modèles graphiques, de niveau plus bas, tels que les automates temporisés (par exemple UPPAAL) et les réseaux de Petri temporisés (par exemple TINA). Les modèles intermédiaires sont un moyen pour combler le fossé qui sépare les langages des modèles graphiques. Par exemple, NTIF (New Technology Intermediate Format) a été proposé pour représenter des processus séquentiels non temporisés qui manipulent des données complexes. Dans cette thèse, nous proposons un nouveau modèle nommé ATLANTIF, qui enrichit NTIF de constructions temps-réel et de compositions parallèles de processus séquentiels. Leur synchronisation est exprimée d'une manière simple et intuitive par la nouvelle notion de synchroniseur. Nous montrons qu'ATLANTIF est capable d'exprimer les constructions principales des langages de haut niveau. Nous présentons aussi des traducteurs d'ATLANTIF vers des automates temporisés (pour la vérification avec UPPAAL) et vers des réseaux de Petri temporisés (pour la vérification avec TINA). Ainsi, ATLANTIF étend la classe des systèmes qui peuvent en pratique être vérifiés formellement, ce que nous illustrons par un exemple.

<p>This study explore the capabilities of Intermediate Phase (grades 4-6) learners in a Quintile 1 school in the Metro Central of Cape Town, through the lens of the capabilities approach theorized by Amartya Sen. This approach relates to how learners are able to utilize their capability sets to attain functionings in the face of poverty i.e. attain the freedom to live the kind of life they value. The study has chosen the capabilities approach because of its high interdisciplinary and multidimensional characteristics. This makes it appropriate to the South Africa context which is characterized by inequality, deprivation and segregation. In this regard, the study explores the features of poverty and forms of capabilities in relation to Intermediate Phase Learners in Quintile 1 Schools. Furthermore the study attempts to explain the effect of poverty on the capabilities of this group of learners in a selected Quintile 1 school in the Metro Central of Cape Town.</p>

Fission is the most important nuclear reaction for society at large today due to its use in energy production. However, this has raised the problem of how to treat the long-lived radioactive waste from nuclear reactors. A radical solution would be to change the composition of the waste into stable or short-lived nuclides, which could be done through nuclear transmutation. Such a concept requires accelerator-driven systems to be designed, where those for transmutation are reactor hybrids. This thesis is a contribution to the knowledge base for developing transmutation systems, specifically with respect to the computational modeling of the underlying nuclear reactions, induced by the incident and secondary particles. Intermediate energy fission cross sections are one important type of such data. Moreover, they are essential for understanding the fission process itself and related nuclear interactions. The experimental part of this work was performed at the neutron beam facility of the The Svedberg Laboratory in Uppsala. Fission cross sections of 238U, 209Bi, natPb, 208Pb, 197Au, natW, and 181Ta were measured for neutrons in the range En = 30-160 MeV using thin-film breakdown counters for the fission fragment detection. A model was developed for the determination of the efficiency of such detectors. A compilation of existing data on proton-induced fission cross sections for nuclei from 165Ho to 239Pu was performed. The results, which constitute the main body of information in this field, were added to the worldwide EXFOR database. The dependences of the cross sections on incident energy and target nucleus were studied, which resulted in systematics that make it possible to give estimates for unmeasured nuclides. Nucleon-induced fission cross sections were calculated using an extended version of the cascade exciton model. A comparison with the systematics and the experimental data obtained in the present work revealed significant discrepancies. A modification of the model was made that significantly improved the predictions.

Reaction cross sections were measured for protons at 65.5 MeV, for deuterons at 37.8, 65.5, 97.4 MeV, for 3He at 96.4, 137.8, 167.3 MeV, and for 4He at 69.6, 117.2, 163.9 and 192.4 MeV. Targets were 9Be, 12C, 16O, 28Si, 40,48Ca, 58,60Ni, 112,116,118,120,124Sn and 208Pb. 48Ca and 118Sn targets were used only for some of the measurements. Rest of the targets have been measured for all energies and projectiles but 4He at 69.6 MeV where reaction cross sections were measured for 9Be, 12C, 16O, 28Si, 40Ca targets. A modification of a standard attenuation technique was used. Details of the experimental design are presented. Experimental uncertainties were 2-3% for p, 3% for d and 3-10% for 3,4He. A strong forward peaking of the reaction products was observed for 3,4He. Therefore the standard reaction cross section measurement technique was not applicable for these projectiles. The forward peaking is also responsible for the increase of experimental uncertainties for these projectiles. The forward peaking of the reaction products is not known for other projectiles and has also not been observed with 3,4He at different - both higher and lower - energies. Possible explanations for this phenomenon are discussed. Optical model calculations of the reaction cross sections are in good agreement with the measured values. The measurements were performed with beams from the Gustav Werner cyclotron at the The Svedberg Laboratory, Uppsala.

A main aspect of wellbore stability analysis is the selection of an appropriate rock failure criterion. The most commonly used criterion for brittle failure of rocks is the Mohr-Coulomb criterion. This criterion involves only the maximum and minimum principal stresses, s1 and s3, and therefore assumes that the intermediate stress s2 has no influence on rock strength. When the Mohr-Coulomb criterion had been developed, it was justified by experimental evidence from conventional triaxial tests (s1&gt;s2=s3). Based on triaxial failure mechanics, the Mohr-Coulomb criterion has been extensively used to represent rock failure under the polyaxial stress state (s1&gt;s2&gt;s3). In contrast to the predictions of Mohr-Coulomb criterion, much evidence has been accumulating to suggest that s2 does indeed have a strengthening effect. In this research, I have shown that Mohr-Coulomb failure criterion only represents the triaxial stress state (s2=s3 or s2=s1), which is a special case that will only occasionally be encountered in situ. Accordingly, I then developed a new true-triaxial failure criterion called the Mogi-Coulomb criterion. This failure criterion is a linear failure envelope in the Mogi domain (toct-sm,2 space) which can be directly related to the Coulomb strength parameters, cohesion and friction angle. This linear failure criterion has been justified by experimental evidence from triaxial tests as well as polyaxial tests. It is a natural extension of the classical Coulomb criterion into three dimensions. As the Mohr-Coulomb criterion only represents rock failure under triaxial stress states, it is expected to be too conservative in predicting wellbore instability. To overcome this problem, I have developed a new 3D analytical model to estimate the mud pressure required to avoid shear failure at the wall of vertical, horizontal and deviated boreholes. This has been achieved by using linear elasticity theory to calculate the stresses, and the fully-polyaxial Mogi-Coulomb criterion to predict failure. The solution is achieved in closed-form for vertical wellbores, for all stress regimes. For deviated or horizontal wellbores, Mathcad programs have been written to evaluate the solution. These solutions have been applied to several field cases available in the literature, and the new model in each case seems to be consistent with the field experience. / QC 20100629

The diffusion of small-molecule penetrants in polyethylene is hindered by impenetrable crystals and by the segmental constraints imposed by the crystals on the penetrable phase. Liquid and vapour n-hexane sorption/desorption measurements were performed on metallocene catalyzed homogenous poly(ethylene-co-octene)s. It was shown that the fractional free volume of the polymer penetrable component increased with increasing amount of penetrable polymer. It also increased with the relative proportion of liquid-like component in the penetrable polymer fraction. The detour effect was found to increase with decreasing crystallinity. The experimental study of the morphology of the polymers showed that the geometrical impedance factor followed the same trend with increasing crystallinity as the data obtained from n-hexane desorption. The changes in phase composition and character upon n-hexane sorption were monitored with Raman spectroscopy, WAXS and NMR spectroscopy. Partial dissolution of the orthorhombic and the interfacial component was observed upon nhexane sorption. Changes in the character of the components were furthermore analyzed: an increase of the density in the crystalline component and a decrease of the density in the amorphous component were observed in the n-hexane-sorbed-samples. Molecular dynamics simulations were used for studying diffusion of n-hexane in fully amorphous poly(ethylene-co-octene)s. The branches in poly(ethylene-co-octene) decreased the density by affecting the packing of the chains in the rubbery state in accordance with experimental data. Diffusion of n-hexane at low penetrant concentration showed unexpectedly that the penetrant diffusivity decreased with increasing degree of branching. Spherulitic growth was mimicked with an algorithm able to generate structures comparable to those observed in polyethylene. The diffusion in the simulated structure was assessed with Monte Carlo simulations of random walks and the geometrical impedance factor of the spherulitic structures was calculated and compared with analytical values according to Fricke’s theory. The linear relationship between geometrical impedance factor and crystallinity in Fricke’s theory was confirmed. Fricke’s theory, however, underestimated the crystal blocking effect. By modelling systems having a distribution of crystal width-to-thickness ratio it was proven that wide crystals had a more pronounced effect on the geometrical impedance factor than is indicated by their number fraction weight. / QC 20100909

The purpose of this study is to learn about educationalists´ apprehensions and their experiences of working with action programmes within the compulsory school's earlier years. Two issues have been composed in order to meet this purpose. They are also the foundation of the interview questions, which are enclosed at the end of the essay. The purpose with the issues is to look into educationalists´ work with action programmes. Another purpose is to find out how they consider an action programme should be formulated in order to function as a support for students in need of special aid. From the study the result shows that the apprehensions of working with action programmes are separating from one teacher to another. The informants of the study indicate the importance differs inviting both pupils and parents to participate in the entire process. They also indicate that the advantage of accuracy in the document and the descriptions for example who´s responsible for what and when the evaluation will be implemented. The study also shows the benefits of having distinct goals and intermediate goals, which are crucial for a successful result and good motivation. / Undersökningens syfte är att ta reda på pedagogers erfarenheter och uppfattningar av arbetet med åtgärdsprogram inom grundskolans tidigare år. För att uppfylla detta syfte har två frågeställningar arbetats fram. Dessa ligger även till grund för de intervjufrågor som bifogats i slutet av uppsatsen. Frågeställningarnas uppgift är att undersöka pedagogers arbete med åtgärdsprogram. De syftar även till att se hur pedagoger anser att ett åtgärdsprogram bör utformas för att på bästa sätt fungera som en hjälp för elever i behov av särskilt stöd. Resultatet från undersökningen visar att uppfattningarna om arbetet med åtgärdsprogram skiljer sig markant. Informanterna påpekar betydelsen av att både elev och vårdnadshavare inbjuds till delaktighet i hela processen kring åtgärdsprogrammet. De beskriver även fördelen med tydligheten i dokumentet, där åtgärden beskrivs, vem som ansvarar för vad samt när uppföljning och utvärdering skall genomföras. Det framgår även att fördelen med att sätta upp tydliga mål- och delmål är avgörande för god motivation och i förlängningen ett lyckat resultat.

Den här högskoleavhandlingen beskriver designen av ett IF-filter samt hårdvarukonstruktion av en ny 77 GHz FMCW-radar demonstrator. Syftet med demonstratorn är att illustrera hur kisel germanium-, SiGe, teknologi kan användas istället för den mer vedertagna men dyrare gallium arsenik-, GaAs, teknologin. Den gamla radar-prototypen vilken Acreo AB utvecklat är funktionell men behöver konstrueras om för att bättre kunna utvärdera radarprestandan. I avhandlingen presenteras grundläggande radarteori och ekvationer för att underlätta förståelsen av de olika systemblocken. Rapporten beskriver också systemarkitekturen och hur dess funktionalitet kommer att testas. Det omdesignade IF-filtret har simulerats i en PSpice-simulator och ett prototypkort av detta har tillverkats för mätningar. Ett 4-lagers kretskort av hela systemet har tagits fram i Orcad Layout. Slutligen innehåller rapporten förslag på förbättringar till nästa demonstratorversion. / This bachelor thesis describes the design of an IF-filter and the hardware construction of a new version of a 77 GHz FMCW-radar demonstrator. The purpose of the demonstrator is to illustrate how the silicon germanium-, SiGe, technology could be used instead of the more conventional but also much more expensive gallium arsenide-, GaAs, technology. The old radar prototype that Acreo AB has developed is fully functional but needs to be redesigned to be able to evaluate the radar performance in a better way. The thesis presents the basic radar theory and equations to help understanding the construction of the system blocks. The report also describes the system architecture and how its functionality should be tested. The redesigned IF-filter has been simulated in a PSpice simulator and a prototype has been manufactured and measured. A 4-layer PCB-board of the whole system was done in Orcad Layout. Finally the report is concluded with suggestions on improvements for the next demonstrator version.

The purpose of this research study is to examine reading assignments given in the secondary classroom of a rural secondary school. The intention is to analyze student readiness to handle complex text found in post-secondary education and/or the workforce, based on current reading trends within the school. The research questions guiding this study focus on the average amount of reading students are expected to complete in a week, what strategic support is being provided to students to enhance comprehension of text, the methodology behind how teachers select both reading assignments and reading strategies, and finally the methodology behind how teachers assess student content learning through assigned text. This study is broken down into three major components: teacher-completed reading logs, student surveys, and two case studies. This mixed methods data collection process revealed that students are typically assigned less than two reading assignments per class per week, however nearly half of these students indicate that they read all of an assigned text. Case study data concluded that teachers are not consistent in their methodology neither in selecting reading assignments nor in utilization of reading strategies. Finally, based on the data, it is reasonable to conclude that students in this setting may not be prepared to handle complex texts found in post-secondary education and/or in the workforce.