Carbon Capture and Storage (CCS) is recognised as having a significant role to play in tackling climate change and reducing carbon dioxide (CO2) emissions. In CCS schemes, CO2 is captured from anthropogenic sources, and transported to suitable sites either for EOR (Enhanced Oil Recovery) or storage. The transport of such huge amount of CO2 causes new challenges. The main concern is in the difference between natural gas and CO2 transportation pipelines. CO2 phase behaviour during decompression, existence of different impurities and very high operating pressure are some of the new challenges for pipeline designer and operators. This PhD study has taken a systematic approach to understand the mechanics involved in the fracture of pipes containing high pressure flue-gas CO2. The work involved the development of a novel weight function stress intensity factor solution that can be used with complex stress fields induced by residual and/or thermal stresses in addition to applied pressure. In addition, the thesis reports a substantial experimented test programme which involved low temperature fracture toughness tests linked to a detailed finite element based stress analysis. Overall, the thesis presents an integrated engineering criticality means to assess the suitability or otherwise of a pipeline system to transport high pressure flue-gas CO2.

Flexible plastic liners are sometimes installed into new and existing oil and gas pipelines to prevent corrosion of the pipe wall. A practical difficulty of this method is that the plastic liners are permeable to gases, which can collect and form an annular space between the liner and the pipe. If the operating pressure in the pipe decreases then the collected gas can cause the liner to collapse and block the pipe. One method for overcoming this problem is to insert vents at intervals along the liner to allow the gas to escape into the pipe during depressurisation. However, there is concern that this arrangement might lead to excessive corrosion beneath the vent where the pipe wall is exposed. The rate of corrosion is expected to be controlled by the vent size but this principle needs to be confirmed by experiment. The work described in this thesis is aimed at investigating this corrosion by experiment for a range of conditions typical of oil and gas production. A novel crevice corrosion cell was designed, consisting of an X100 carbon steel plate and a sheet of transparent Perspex, separated by a thin gasket. A small hole in the Perspex simulated a liner vent and allowed carbon dioxide to reach the steel surface. Tests were carried out in 3.5% NaCl solutions saturated with carbon dioxide at 1 bar partial pressure. Corrosion rates along the length of the annular space were measured using the Linear Polarisation Resistance (LPR) technique on pairs of insulated X100 electrodes set into the plate. The corrosion rates within the annular space have been shown to be small compared to those in the bulk solution and to diminish rapidly with distance from the vent. Mathematical modelling, based on the transport of carbon dioxide, is described to explain these findings and support the experimental work. The effectiveness of the LinerVentTM, installed over the vent, in a turbulence pipeline was demonstrated. The benefit of applying cathodic protection within the annular space was also demonstrated. The results are discussed in terms of the fundamental corrosion principles and their practical implications

Morphologic change of ephemeral stream cross-sections is a natural component of fluvial geomorphology but disruptions to natural erosion and deposition by anthropogenic disturbances has the potential for cascading impacts down the channel corridor. The proximal impact of a natural gas pipeline construction on ephemeral stream cross-section geometry in southern Arizona was evaluated from July 2014 (pre-construction) to July 2016 (two years post construction). Cross-sections at three locations (upstream the pipeline Right-Of-Way (ROW)), through the middle of the ROW, and downstream of the ROW) were measured using Light Detection And Ranging (LIDAR) and field methods for 16 ephemeral streams. Results of both the LIDAR and field measurements indicated insignificant difference in cross-sectional area change between upstream, across, and downstream-ROW cross-sections [(F 2,64) = 0.341, p = 0.73; (F2,18)= 0.980, p = 0.395]. Sediment generated during pipeline construction appeared to have moved beyond the physical confines of the study site, which limited the assessment of larger-scale geomorphic impacts. Furthermore, the 2014-2016 study period experienced only small (high-recurrence frequency) precipitation events, indicating the absence of large flows capable of significant morphologic change. To further explain differences in cross-section area change between LIDAR datasets, a linear regression model was used to assess the predictive value of nine variables: year of measurement, drainage area, drainage density, basin slope, upstream-, across-, downstream-ROW cross-section locations, percent bare soil in basin, percent mesquite in basin, total precipitation, and number of storms with average precipitation above 25 mm/hour. Though the amount of bare soil in the basin and the second study period (February 2015-July 2016) at least partially explained the changes in cross-section area, the model was not a strong predictor of morphologic change during the 2014-2016 study period. The majority of the variability in cross-sectional area change in the study basins remained unexplained.

More people are striving for increased levels of educational attainment as a result of a global shift towards a more knowledge based economy. Schools and communities have adjusted to this societal change by seeking alignment along the educational pipeline from preschool (P) to graduate school (20), otherwise known as P-20 reform. This reform often develops with the collaboration and guidance of specific P-20 leadership councils that exist at both the local and state levels. The main purpose of this qualitative study was to go beyond the mere descriptions of P-20 councils to examine the policy pathways chosen by P-20 councils, specifically the relationship between policy context, design, and implementation of P-20 reform. Texas and Tennessee were selected as case sites for a cross comparison policy analysis that utilized interviews and document analysis to examine leadership and contextual influences to the reform, with a focus on state and local P-20 councils. An interpretive theoretical framework helped garner the meaning-making of policy leaders throughout the movement’s existence, while Kingdon’s multiple streams model helped organize the episodic nature of policy. Findings showed varied approaches within and between states leading to mixed levels of sustained P-20 councils and leadership. Finally, best practices for P-20 councils are shared as the problems P-20 seeks to address continue to persist and the P-20 movement adapts to a changing local and national context focused on college and career readiness.

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

This thesis deals with the design and implementation of an optimizer and a transformer of relational queries. Firstly, the thesis describes the theory of the relational query compilers. Secondly, we present the data structures and algorithms used in the implemented tool. Finally, the important implementation details of the developed tool are discussed. Part of the thesis is the selection of used relational algebra operators and design of an appropriate input. Input of the implemented software is a query written in a XML file in the form of relational algebra. Query is optimized and transformed into physical plan which will be executed in the parallelization framework Bobox. Developed compiler outputs physical plan written in the Bobolang language, which serves as an input for the Bobox. Powered by TCPDF (www.tcpdf.org)

Grâce aux progrès réalisés dans le domaine des semi-conducteurs, les plateformes matérielles embarquées sont capables de satisfaire les contraintes de performances d'applications de plus en plus complexes. Cette augmentation conduit à une explosion des coûts de conception, ce qui pousse les concepteurs de ces plateformes à utiliser des outils travaillant à des niveaux d’abstraction plus élevés. Aujourd’hui, les outils de synthèse de haut niveau opèrent sur des descriptions C/C++ pour en générer des accélérateurs matériels spécialisés. Ces outils offrent des gains en productivité significatifs par rapport à la génération précédente, qui opérait sur des descriptions structurelles de l’architecture en VHDL ou Verilog. Ces descriptions algorithmiques doivent être retravaillées pour que les outils puissent générer des circuits performants. Pour faciliter cette tâche, une solution consiste à mettre en œuvre une boite à outils pour des transformations source-à-source orientées synthèse de haut niveau. En particulier, cette thèse s’intéresse aux transformations de boucles, avec pour objectif d’améliorer les performances en exposant des boucles parallèles et en améliorant la localité des accès mémoire. En nous appuyant sur une représentation des boucles dans le modèle polyédrique, nous proposons une approche qui améliore l’applicabilité du pipeline de nids de boucles en vérifiant sa légalité de manière plus précise que les approches existantes. De plus, lorsque la vérification échoue, nous proposons une technique de correction qui insère statiquement des états d’attente pour assurer la légalité du pipeline. Enfin, ce pipeline est mis en œuvre en utilisant une technique de génération de code qui met les nids de boucles à plat. Ces contributions ont été implémentées dans l’infrastructure de compilation source-à-source Gecos, avant d’être appliquées à un ensemble de benchmarks représentatifs des noyaux de calculs cibles de la synthèse de haut niveau. Les résultats montrent un gain en performances significatif, avec un surcoût en surface modéré. / Due to the advances in semiconductor technologies, embedded hardware is capable of satisfying the performance constraints of increasingly complex applications. This leads to a design cost explosion, thus pushing the hardware designers to use tools working with higher levels of abstractions. High-Level Synthesis tools generate custom hardware accelerators out of C/C++ specifications. They offer significant productivity gains compared to the previous generation of tools that worked at the level of hardware description languages, such as VHDL or Verilog. These higher level specifications have to be reworked in order for the High-Level Synthesis tools to generate efficient hardware accelerators. To ease this task, one solution is to provide a source-to-source transformation toolbox targeting High-Level Synthesis. Specifically, this thesis explores loop transformations in order to improve performance by exposing parallel loops and improving the locality of memory accesses. Using polyhedral representation of loop nests, we propose an approach to improve the applicability of nested loop pipelining by verifying its legality in a more precise way than existing approaches. Moreover, we propose a correction mechanism that statically inserts wait states for enforcing the pipeline legality for cases when the verification fails. The resulting pipeline is implemented using a code generation technique that flattens the loop nests. These contributions have been implemented within the GeCoS source-to-source compilation infrastructure, and applied to a set of benchmarks targeted towards High-Level Synthesis. Results show significant performance improvement at the price of a moderate area overhead.

Research in academia and industry continues to identify a decline in enrollment in computer science. One major component of this decline in enrollment is a shortage of female students. The primary reasons for the gender gap presented in the research include lack of computer experience prior to their first year in college, misconceptions about the field, negative cultural stereotypes, lack of female mentors and role models, subtle discriminations in the classroom, and lack of self-confidence (Pollock, McCoy, Carberry, Hundigopal, & You, 2004). Male students are also leaving the field due to misconceptions about the field, negative cultural stereotypes, and a lack of self-confidence. Analysis of first year attrition revealed that one of the major challenges faced by students of both genders is a lack of problem-solving skills (Beaubouef, Lucas & Howatt, 2001; Olsen, 2005; Paxton & Mumey, 2001). The purpose of this study was to investigate whether specific, non-mathematical problem-solving instruction as part of introductory programming courses significantly increased computer programming self-efficacy and achievement of students. The results of this study showed that students in the experimental group had significantly higher achievement than students in the control group. While this shows statistical significance, due to the effect size and disordinal nature of the data between groups, care has to be taken in its interpretation. The study did not show significantly higher programming self-efficacy among the experimental students. There was not enough data collected to statistically analyze the effect of the treatment on self-efficacy and achievement by gender. However, differences in means were observed between the gender groups, with females in the experimental group demonstrating a higher than average degree of self-efficacy when compared with males in the experimental group and both genders in the control group. These results suggest that the treatment from this study may provide a gender-based increase in self-efficacy and future research should focus on exploring this possibility.

The main theme of this dissertation is to develop a distributed computational pipeline for processing next-generation RNA sequencing (RNA-seq) data. RNA-seq experiments generate hundreds of millions of short reads for each DNA/RNA sample. There are many existing bioinformatics tools developed for the analysis and visualization of this data, but very large studies present computational and organizational challenges that are difficult to overcome manually. We designed a comprehensive pipeline for the analysis of RNA sequencing which leverages many existing tools and parallel computing technology to facilitate the analysis of extremely large studies. RNA CoMPASS provides a web-based graphical user interface and distributed computational pipeline including endogenous transcriptome quantification and additionally the investigation of exogenous sequences.