This project is in collaboration with the Hydro-Quebec Research Institute (IREQ) and the Canadian Centre for Electron Microscopy (CCEM) on the mechanical test performance of miniature-scale micro-tensile specimens. The objective of the thesis project is to create an efficient and reliable fabrication route for producing micro-tensile specimens and to validate the accuracy of a newly custom-built micro-tensile bench at IREQ. The fabrication techniques developed and outlined in this thesis use the underlying fundamental physical mechanisms of secondary electron microscopy (SEM), focused-ion beam (FIB), and the femtosecond (fs)-laser machining for producing optimal quality micro-tensile specimens. The mechanical testing of the specimens is geared towards studying the localized deformation occurring in the microstructure when the size of the specimen only limits a number of grains and grain boundaries in order to target the specific detailed measurement of the mechanical behaviour of individual grains and interfaces. The goal for creating an optimal fabrication route for micro-tensile specimens is to carry out micro-mechanical testing of the primary turbine steels of 415 martensitic stainless steel used in the manufacture of Francis turbine components at Hydro-Quebec. The mechanical testing of single phase and interphase interface 415 steel micro-tensile specimens are considered building blocks to developing digital twin models of the steel microstructure. The experimental data from the mechanical tests would be fed into the crystal plasticity finite element models (CPFEM) that are currently being developed by researchers at IREQ. With the development of digital twin models, engineers at IREQ would be able to predict crack initiation at the microstructure level (prior to crack propagation into macro-scale cracks) by observing the evolution of the grain’s crystallographic orientation and morphology, as well as deformation mechanisms such as martensite formation and twinning produced from localized induced strains in the microstructure. In addition, self-organized dislocation processes such as dislocation nucleation and dislocation escape through the free surface can also be studied using the CPFEM models for size-limited mechanical deformation behaviour of miniature-scale mechanical test specimens. The fabrication routes studied in this thesis project use the combination of the fs-laser and plasma focused ion beam (PFIB) to machine the micro-tensile specimens. (100) single crystal copper was the ideal material chosen to validate the accuracy of the micro-tensile bench and quality of the fs-laser-machined tensile specimens, due to its ductile nature and well-characterized properties studied in literature. A mechanical size effect was studied for single crystal copper specimens with different gauge thicknesses. It was observed from the micro-tension testing that the strength of the specimens increased with decreasing gauge thickness occurring in the size-limited tensile gauges. In addition, it was determined there was negligible differences in the size effect seen between the PFIB-machined copper micro-tensile specimens and the fs-laser-machined micro-tensile specimens, demonstrating that the fs-laser is a reliable machining route for the micro-tensile specimens. X-ray computed tomography was used to validate the correct geometry of the machined gauge section produced from an innovative gauge thinning method adopted from IREQ’s research collaborator, Dr. Robert Wheeler. As well, finite-element analysis (FEA) was performed to determine the deformation behaviour under both linear-elastic and non-linear elastoplastic conditions of (100) copper and 415 steel models simulated in pure tension, prior to the fabrication of the micro-tensile specimens, respectively. Furthermore, significant progress has been made towards targeting martensite grains in the 415-steel microstructure using electron backscattered diffraction (EBSD) analysis to produce single crystal and interphase interface micro-tensile specimens. A workflow towards grain targeting using EBSD analysis has been developed, as well as for the relocation of grains using reference fiducial marks for future fabrication of the single crystal and interphase interface 415 micro-tensile specimens. / Thesis / Master of Applied Science (MASc) / Hydro-Quebec is an energy utilities company that operates the design of Francis hydro-turbines to supply hydroelectric power across the province of Quebec. The hydro-turbines have an expected service life of 70 years. Unfortunately, the turbines can get replaced by new ones prior to reaching half of its service life, due to the development of severe fatigue crack growth in the primary components of the turbines. A solution proposed by the researchers at the Hydro-Quebec Research Institute (IREQ) is to determine a linkage between the turbine’s steel’s microstructure and the mechanical behaviour of the turbine steels. Deformation of the material starts at the microstructure level, where dislocations glide through the material lattice, causing both reversible (elastic) and irreversible (plastic) deformation. Therefore, a solution was proposed by the researchers at IREQ to create computational models of the steel microstructure to predict the deformation of the steel’s microstructure. Being able to predict the deformation mechanisms through the simulation models of the microstructures allows for engineers at Hydro-Quebec to schedule regular maintenance of the turbines more efficiently and provide metallurgists the knowledge on what is occurring at the microstructure level and what can be done to improve the chemical and physical composition of the steel. To develop the digital twin models, experimental data must be collected through mechanical testing of miniature mechanical test specimens of the turbine steels. The mechanical properties of the single phases and interphase interface specimens are fed into the models as building blocks to building a microstructure map of the turbine steels. Micro-tension testing of micro-tensile specimen provides direct information about the material’s mechanical properties. In this work, a reliable and efficient fabrication route for micro-tensile specimens was developed for the purpose of extracting mechanical properties of single phase and interphase interface turbine steel specimens using focused ion beam (FIB) and femtosecond laser machining.

The research focuses on analysis and subsurface imaging of siliciclastics rocks on steam-affected 3D poststack seismic data, merged from different vintages, from the Temblor Formation in the Coalinga heavy oil reservoir in the San Joaquin basin, California. The objective was identification, delineation, and demarcation of reservoir heterogeneities by seismostratigraphic and seismogeomorphic analysis. The proximity of the San Andreas Transforms greatly controlled basin evolution and caused substantial reservoir heterogeneity by changing the depositional environment from shallow marine to near-shore fluvial. Moreover, two unconformities dissect the reservoir interval. The seismic dataset exhibits erratic, distorted reflection strengths and amplitudes caused by steam-injection-aided production. A petrophysical analysis based on Gassmann fluid substitution suggests a 27% P-wave velocity decrease in steam-saturated intervals. Seismic to well log ties were problematic and vexing due to the resulting statics, wavelet changes, and line mismatches. Mapping and flattening on a deeper horizon, however, allowed mapping of the internal unconformities and well ties which were crucial for seismostratigraphic sequence identification. Visualization of seismic attributes brought out stratification patterns and two distinct, laterally and vertically extensive, porous, and interconnected facies tracts interpreted as incised valley fills and tidal-to-subtidal deposits as evidenced by bright, steam related amplitudes. Seismic attribute analysis, Geobody Visualization and Interpretation, and structure and isochron maps brought out two prominent channel-systems, recut and restacked in the central part of the area. These deposits were identified on seismic data and correlated to high-gamma coarsening-upward sands on logs and cores. The deeper one, shifting towards SSE with depth, lies between the Base Temblor and Buttonbed unconformities both in the southwestern and northwestern parts of the study area and is scattered in the western-central portion. The shallower one originates in southwestern corner below the Top Temblor unconformity shifts towards ESE-SE with depth, and runs nearly parallel to the Top Temblor unconformity. It cuts across the Valv unconformity in central part creating a channel incision, and follows the Buttonbed unconformity towards the north. The investigation segmented the reservoir into channels, non-channel bearing, and unconformity-bounded subunits which will allow the operator to improve steam injection and optimize placement of oil producing infill wells. / Ph. D.

The calculation of the loadbearing capacity of hollow section joints using the design formulas according to EN 1993-1-8 assumes full-strength welded connections if the non-linear stress distribution over the circumference is not covered by calculation. Sufficient ductility in the connections ensures a plastic redistribution capacity within each joint. In the case of hollow section structures made of high-strength steels, it becomes more difficult to meet the requirement for full-strength welds as the yield strength of the base material increases. This article begins with a summary of the current rules for the design and execution of welded hollow section joints. The softening behaviour of high-strength steels and the loadbearing capacity of welded connections with local softening in the HAZ are then discussed. That is followed by the presentation of the results from the AiF-FOSTA research project P1020 regarding the influence of manufacturing parameters on the properties of welded connections and the HAZ. The experimental test programme for single-sided welded T-connections and the parameter studies within the research project P1453 are also described. Finally, a design approach is presented to account for HAZ failure and hybrid failure modes of hollow section connections.

Evidence suggests that caring for orphans and vulnerable children affected by HIV and AIDS remains one of the greatest challenges facing South Africa. Statistics indicate that there are 1.91 million AIDS orphans in the country (UNICEF, 2012; Statistics South Africa, 2009:8)). The majority of these orphans live in rural and poor urban households. Caring for orphans and vulnerable children places severe strain on support systems, such as the extended family; this spills over into the community. Providing care and support also places an extra burden on the already overstretched welfare sector and drains state resources. The primarily objective of this study was to explore community resilience strategies on challenges faced by orphans and vulnerable children affected by HIV and AIDS in Ekurhuleni Metropolitan Municipality, Gauteng. A purposive sample of 32 participants was selected and field data were collected over a period of two months using a structured research guide. A combination of data collection methods was employed in order to explore different perspectives of community resilience strategies on challenges faced by orphans and vulnerable children affected by HIV and AIDS in Benoni. Emerging data illustrate a clear account on the impact of the AIDS epidemic in Benoni. All of the respondents were directly or indirectly affected by the epidemic. This should be located within the high prevalence of HIV and AIDS and the high number of orphans in Ekurhuleni. The study findings further suggest a correlation between socioeconomic challenges and the AIDS epidemic in Ekurhuleni. This is demonstrated through the challenges experienced by orphans and vulnerable children in Benoni, which include: non-disclosure by parents of their illness; economic deprivation and disrupted schooling; children caring for an ill parent with AIDS and child-headed households; emotional, sexual and economic exploitation, stigmatisation and discrimination. Despite these challenges, through community resilience the Benoni community has taken some initiatives to mitigate against these challenges. This includes the establishment of a community based organisation which provides basic services to orphans and vulnerable children in Benoni. To date this organisation has successfully provided material and psychosocial to more than 278 orphans. The success of this initiative confirms the importance of community driven interventions using the resilience framework to supports orphans and vulnerable, rather than dependency on the government imposed programmes- top down approach. However, community based programmes need to be strengthened by the government and non-governmental organisations in order to maximise benefits. / Psychology / M.A. (Social Behaviour Studies)

The present dissertation reports the findings of a study of cracking behavior of a newly developed superalloy, Allvac 718Plus during high power beam welding and post-weld heat treatment. Microstructures of the base alloy, heat affected zone (HAZ) and fusion zone (FZ) of welded and post-weld heat treated (PWHT) coupons were examined by the use of standard metallographic techniques involving optical microscopy, analytical scanning electron microscopy (SEM) and analytical transmission electron microscopy. Moreover, grain boundary segregation behavior of boron atoms during pre-weld heat treatments was evaluated using secondary ion mass spectroscopic system. In the first phase of the research, 718Plus was welded using a low and high heat input CO2 laser to assess its weld cracking response. Detailed examination of the welds by analytical electron microscopic technique revealed the occurrence of cracking in the HAZ of low heat input welds, while their FZ was crack free. However, both the FZ and HAZ of high heat input welds were crack-free. Resolidified constituents were observed along the cracked grain boundaries of the lower heat input welds, which indicated that HAZ cracking in this newly developed superalloy was associated with grain boundary liquation. However, despite a more extensive liquation of grain boundaries and grain interior in the HAZ of high heat input welds, no cracking occurred. This was attributed to the combination of lower welding stresses generated during cooling, and relaxation of these stresses by thick intergranular liquid. Although HAZ cracking was prevented by welding with a high heat input laser, it resulted in a significant damage to the parent microstructure through its extensive liquation. Thus, the use of low heat input welding is desirable. However, this resulted in HAZ cracking which needs to be minimized or eliminated. Therefore, during the second phase of this research, the effects of pre-weld thermal processing on the cracking response of 718Plus were investigated. Results from the quantification of the cracking of the alloy showed that HAZ cracking may be significantly reduced or eliminated through an adequate selection of pre-weld thermal cycle. In the third stage of this research, crack-free welds of 718Plus were post-weld heat treated using standard thermal schedules. A significant solid state cracking of the alloy occurred during the PWHT. The cracking was attributed to the presence of embrittling phases on HAZ grain boundaries, coupled with aging contraction stresses that are generated by a considerable precipitation of gamma prime phase during aging.

The present dissertation reports the findings of a study of cracking behavior of a newly developed superalloy, Allvac 718Plus during high power beam welding and post-weld heat treatment. Microstructures of the base alloy, heat affected zone (HAZ) and fusion zone (FZ) of welded and post-weld heat treated (PWHT) coupons were examined by the use of standard metallographic techniques involving optical microscopy, analytical scanning electron microscopy (SEM) and analytical transmission electron microscopy. Moreover, grain boundary segregation behavior of boron atoms during pre-weld heat treatments was evaluated using secondary ion mass spectroscopic system. In the first phase of the research, 718Plus was welded using a low and high heat input CO2 laser to assess its weld cracking response. Detailed examination of the welds by analytical electron microscopic technique revealed the occurrence of cracking in the HAZ of low heat input welds, while their FZ was crack free. However, both the FZ and HAZ of high heat input welds were crack-free. Resolidified constituents were observed along the cracked grain boundaries of the lower heat input welds, which indicated that HAZ cracking in this newly developed superalloy was associated with grain boundary liquation. However, despite a more extensive liquation of grain boundaries and grain interior in the HAZ of high heat input welds, no cracking occurred. This was attributed to the combination of lower welding stresses generated during cooling, and relaxation of these stresses by thick intergranular liquid. Although HAZ cracking was prevented by welding with a high heat input laser, it resulted in a significant damage to the parent microstructure through its extensive liquation. Thus, the use of low heat input welding is desirable. However, this resulted in HAZ cracking which needs to be minimized or eliminated. Therefore, during the second phase of this research, the effects of pre-weld thermal processing on the cracking response of 718Plus were investigated. Results from the quantification of the cracking of the alloy showed that HAZ cracking may be significantly reduced or eliminated through an adequate selection of pre-weld thermal cycle. In the third stage of this research, crack-free welds of 718Plus were post-weld heat treated using standard thermal schedules. A significant solid state cracking of the alloy occurred during the PWHT. The cracking was attributed to the presence of embrittling phases on HAZ grain boundaries, coupled with aging contraction stresses that are generated by a considerable precipitation of gamma prime phase during aging.

This thesis deals with globalisation of markets. It focuses on examining the economic crisis of 2008 and 2010 and on how individual countries can cope with deteriorating of macroeconomic values, especially with financial implications of this situation. The thesis also examines credit rating agencies as indicators of financial soundness of investment instruments, to which is often reffered as to culprits of the crisis for their reaction to the development of the mortgage market. The thesis defines the rating in the concept of sovereign states and describes the market of credit rating agencies. It further evaluates individual rating agencies and practices in the context of the crisis, bringing a comprehensive picture of the role they played at the beginning of the crisis. It also attempts to outline more points of view on the previously unilaterally and predominantly negatively perceived issue of reputation of credit rating agencies.

South Africa has been affected both economically and socially by HIV/AIDS. The South African government has put policies in place to support people infected and affected by HIV/AIDS and to ensure that they are not discriminated against. Many children have lost either one or both parents to this pandemic. The purpose of this research study was to explore community-based care for HIV/AIDS orphans. The research question for the study was: “What are the key components of community-based care for HIV/AIDS orphans?” The objectives for this study were as follows: -- To conceptualise community-based care for HIV/AIDS orphans. -- To determine the directions and limitations with regard to community-based care within the current policy framework for caring for children infected and affected by HIV/AIDS. -- To identify the components of Heartbeat’s model for community participation for community-based care of HIV/AIDS orphans. -- To determine the key components for effective community-based care in the care of HIV/AIDS orphans, to serve as guidelines for a sustainable community-based care model for these children. This was an exploratory study. The researcher made use of a case study, which is a type of a qualitative research strategy. Twenty HIV/AIDS orphans, six caregivers and one volunteer were interviewed and a semi-structured interview schedule was used to gather data. Some of the key findings for this study were the significance of community participation, care and support in the placement of HIV/AIDS orphans which guided the key components for sustainable community-based care for HIV/AIDS orphans. The study identified specific challenges in getting communities to participate in the care and support of HIV/AIDS orphans. The study made the following recommendations based on the research findings: -- The revision of policies and guidelines addressing children infected and affected by HIV/AIDS. -- The drafting and implementation of monitoring and evaluation mechanisms for community-based care for HIV/AIDS orphans. -- The Government’s involvement in pledging more resources for HIV/AIDS orphans. / Dissertation (MSD (Social Development and Policy))--University of Pretoria, 2007. / Social Work and Criminology / unrestricted

Les personnes touchées par le cancer (PTC) présentent des besoins de nature diverse. Les résultats de plusieurs études démontrent que la réponse à ces besoins n’est pas optimale et que des actions coordonnées et concertées entre les équipes spécialisées en cancérologie et les organismes du tiers secteur favoriseraient une complémentarité des soins et services offerts aux PTC et, ainsi, une meilleure réponse à leurs besoins. Dans ce contexte, cette étude s’intéresse au point de vue des PTC quant aux interactions entre les équipes spécialisées en cancérologie et les organismes du tiers secteur. Cette étude qualitative descriptive et interprétative a été réalisée auprès de dix femmes et un homme, touchés par le cancer. Les données ont été recueillies à l’aide d’entretiens individuels semi-dirigés. Les résultats obtenus à la suite de l’analyse thématique des données démontrent que les PTC perçoivent peu ou pas d’interactions entre les équipes spécialisées en cancérologie et les organismes du tiers secteur. L’insuffisance d’actions coordonnées, les informations offertes de manière passive ou informelle par les équipes spécialisées en cancérologie ainsi que les contraintes liées à l’accessibilité des services du tiers secteur expliquent l’invisibilité des interactions entre les secteurs, aux yeux des PTC. Des actions coordonnées entre les équipes spécialisées en cancérologie et les organismes du tiers secteur, des références personnalisées réalisées en fonction des besoins singuliers des PTC et un accompagnement personnalisé par un professionnel ou une autre PTC, sont souhaitées par les PTC. / People affected by cancer (PAC) have a variety of needs. The results of several studies show that the response to these needs is not optimal and that coordinated and concerted actions between specialized cancer teams and third-sector organizations would promote complementary care and services for PAC and thus better meet their needs. This study looks at the perspective of people affected by cancer regarding interactions between cancer teams and third sector organizations. This qualitative descriptive and interpretive study was conducted among ten women and one man affected by cancer. Data were collected using semi-structured individual interviews. The results obtained from the thematic analysis of data collected in individual interviews show that PAC perceive little or no interaction between cancer teams and organizations in the third sector. Insufficiency of coordinated action, information offered passively or informally by specialized cancer teams and constraints related to the accessibility of third sector services explain invisibleness of interactions between sectors in the eyes of PAC. Coordinated actions between specialized cancer teams and organizations in the third sector, personalized references made according to the unique needs of PAC, materialized by the presence of a "central" person or a pivotal nurse as well as support for professional navigation or another PAC, are desired by the PAC.

PhD (Public Health) / Department of Public Health / The well-being of adolescents’ population is a major concern to policy makers, educators and researchers all over the world. Research has shown that adolescents engage in deviant and risky sexual behaviour, and such behaviour may have consequences for their present or future health. Likewise, it has been shown that adolescents are also known to conform to societal norms if they are given proper guidance. In the light of this, the present study proposed to explore and explain the influence of family dynamics in the occurrence of adolescents deviant and sexual risk behaviour. This study involved a sequential explorative, descriptive and analytic mixed method design, combining both qualitative and quantitative research approaches. The study was divided into three (3) phases. Phase 1 was purely qualitative in nature, where a total of 10 parents and 13 adolescents were engaged in an in-depth interview. Phase 2 was quantitative in nature, using a cross-sectional analytic design involving 388 adolescents, while Phase 3 was the development of a public health intervention to mitigate the influence of family dynamics on adolescent deviant and sexual risk behaviour. The qualitative data were analysed using thematic content analysis, while the quantitative data were analysed using the Statistical Package for Social Sciences (SPSS) version 22. The Chi-square test, Fisher’s exact test, multinomial and binary logistic regression were used to compare differences between the dependent and independent variables. The level of statistical difference was set at p<0.05. Couple conflicts was a common finding in the study. In addition, many families suffered severe financial constraints and some parents were disconnected from their children physically, emotionally and financially (particularly the fathers). Adolescents claim that the age difference between them and their parents remains a barrier to communication, in addition, some participants claimed that they received little or no sex education from their parents. The present study found a high level of recent physical violence (30%), alcohol (52.9%) and drug use (10%) among participants. The level of sexual activity in this study was high, with 60.1% of the participants being sexually active and 23.1% having been pregnant. In addition, only 35.6% using condoms regularly. There was gender difference among participants on the following variables: cigarette smoking, teenage pregnancy and having multiple sexual partners. Furthermore, participants differed significantly across age group on the following variables: cigarette smoking, sexual activity, having friends who are sexually active, reported pregnancy and currently having iii a relationship. However, ‘relationship with mother’ was the family dynamic variable that recorded a wider effect on deviant and sexual risk behaviour. Furthermore, age, duration of stay in the community, living with siblings, relationship with mother, having enough money at home, being supported emotionally at home and parental love for each other, were predictors of deviant and sexual risk behaviour in the present study. There was also low level of risk perception and low level of skill for self-protection among the participants. As part of the objectives of the present study, the study findings were used to develop an evidence-based public health programme targeted at vulnerable adolescents and adolescents at high risk for deviant and sexual risk behaviour. It is hoped that this programme will be able to empower parents and caregivers to apply better parenting practices to forestall undue exposure of adolescents to factors that contribute to deviant and sexual risk behaviour. The present study demonstrated that although adolescents have the propensity for deviant behaviours, many may transit to adulthood without much adverse sequelae even in the face of harsh family social and economic adversities. However, a proportion of the adolescent population in this community remains vulnerable due to the effects of family de-structuring, poverty and unemployment. / NRF