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A practical engineering design problem is used to examine the over-conservativeness of designs obtained using deterministic optimization with worst-case parameter assumptions and a safety factor. Additionally, an attempted application of reliability-based design optimization (RBDO) demonstrates the limits of RBDO for practical problems. The design problem considered here is TESCO's Internal Casing Drive System (ICDS), which is used in feeding pipeline, or casing, into predrilled holes. After developing a finite element model of the ICDS, experimental data is used to successfully validate modeling methods and assumptions. The validated model is then subjected to multiple analyses to determine an appropriate design configuration to be used as the starting point for optimization. Worst-case, safety factor-based design optimization (SFBDO) is then applied considering two and three design variables, and is successful in increasing the critical load of the ICDS, Pcrit, by 35% and 45%, respectively. An efficient and recognized RBDO method, Sequential Optimization and Reliability Assessment, is selected for application to the design problem to determine an optimum design based on reliability. Due to the optimization formulation, however, SORA cannot be applied. The ICDS design problem represents a practical example that demonstrates the difficulties and limits in applying RBDO to practical engineering design problems. To evaluate the over-conservativeness of worst-case SFBDO, structural reliability analysis is performed on the deterministic optimum designs. It is found that the value of Pcrit for both the two and three variable optimum designs can be increased by 53% while maintaining acceptable probability of failure, demonstrating the over-conservativeness of the worst-case SFBDO. / Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2008-09-05 10:51:26.273

Background: Farming is an hazardous occupation. The underlying determinants of farm injury are not well understood among adolescent populations, particularly from a gender lens. Objectives: (1) To evaluate the association between gender and occupational health and safety practices reported for hazardous work among working adolescent farm children; and, (2) to evaluate the association between use of such practices and time to farm injury, and also whether such associations vary by gender. Methods: Survey data from an existing farm injury cohort were available for analysis. Occupational health and safety practices were: non-use of personal protective equipment, non-use of training and supervision for work with heavy equipment, non-use of training and supervision for work with large animals, and conduct of hazardous tasks. Logistic regression was used to examine associations between gender and use of safety practices, and Cox regression was used to examine relationships between occupational health and safety practices and time to first injury. Results: Girls reported increased odds for the non-use of personal protective equipment (adjusted OR 2.39 [95% CI: 1.16, 4.94]). There was no evidence of an association between gender and the conduct of hazardous tasks (adjusted OR 0.69 [95% CI: 0.28, 1.73]). Gender patterns surrounding non-use of training and supervision for work with equipment (adjusted OR 2.38 [95% CI: 0.53, 10.66]) and with animals (adjusted OR 1.52 [95% CI: 0.75, 3.06]) were not significant. Use of personal protective equipment (adjusted HR 1.25 [95% CI: 0.76, 2.06]) did not significantly reduce the risk of farm injury, neither did use of training and supervision during equipment work (HR 1.25 [95% CI: 0.69, 2.28]), nor during animal work (HR 1.06 [95% CI: 0.59, 1.92]), or the conduct of hazardous tasks (HR 1.04 [95% CI: 0.67, 1.63]). Further, there was no significant modification of these associations and injury by gender. Conclusions: Among adolescents, farm occupational health and safety practices appear to vary by gender. Girls on farms report fewer exposures to hazards, and receive less training and supervision and less use of personal protective equipment, consistent with assigned tasks. While gender appears to play a role in the assignment of farm tasks and occupational health and safety practices, these practices did not reduce the likelihood of subsequent injury. As well, the latter associations did not appear to vary by gender. A public health approach that recognizes gender as a determinant of hazardous farm exposures and associated occupational health and safety practices is needed. / Thesis (Master, Community Health & Epidemiology) -- Queen's University, 2010-09-19 19:25:41.479

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This thesis focuses on the issue of occupational injuries. There are four different explanations of why accident rates vary. A set of research hypotheses were created based on these explanations. Multivariate regression analyses of aggregate secondary data were used to test four hypotheses. The findings of these analyses indicate that establishment size, unionization rates and strike and lockout rates are related to injury rates but earnings are not. A fifth hypothesis was tested using the mining industry of Ontario as a case study. This analysis indicates that safety-related legislative and regulatory changes were not effective in reducing either fatal injuries or non-fatal injuries.

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