Thesis (Ph. D.)--University of Oklahoma, 1998. / Includes bibliographical references (leaves 210-216).

This thesis focuses on exploring figure-ground within the amorphous suburban green space of Calgary, Alberta. It is an edgeless prairie city, flooded with unused space and tethered by freeways that stretch toward the infinite horizon beyond the mountains. The incessant need to own and parcel nature has created a landscape of excess where both city and nature are a blur at the edge of our distracted vision. Using expanded defi nitions of figure-ground as a design methodology, this thesis attempts to better understand this paradox and to act in its middle ground. Articulating a heterotopia between the ideal with the real, the public and the private, the natural and the artificial, this thesis explores a new imaginative space, delicately but firmly tethered to suburban ground and its elusive horizon. The results manifest in unexpected geometries on a thin strip of park between a backyard and a freeway in Calgary.

Every species has a limit to its geographic distribution. The problem is that we don’t really know why. Classical explanations propose that range limits occur where the ecological conditions overwhelm adaptation and populations are no longer self-sustaining. It is generally expected that population abundance and fitness decline towards range margins across a gradient of declining habitat quality. Current evolutionary and theoretical explanations of range limits predict that this geographic pattern of demography will result in genetic constraints in marginal populations, such that range expansion is thwarted by reduced evolutionary potential. In this thesis, I tested the key assumptions and predictions of range limit theory through an empirical evaluation of two coastal dune, endemic plants; Camissonia cheiranthifolia (Spreng.) Raim. (Onagraceae) and Abronia umbellata L. (Nyctaginaceae). In geographic wide surveys of a large proportion of populations across both species’ ranges, neither species exhibited declining abundance or performance towards its range limits. Central populations of C. cheiranthifolia tended to have a higher production of seeds per unit area than marginal populations. Although this pattern demonstrated the potential for gene flow from central sites to swamp selection in marginal sites, results from a transplant experiment suggested that this was unlikely. Experimental populations of C. cheiranthifolia originating from ≥ 675 km south of the northern range limit exhibited similar levels of fitness when planted at the range margin. Along a 200 km transect across the limit, and in contrast to expectations, fitness of all populations increased towards the limit and generally remained high beyond the limit. Individuals from all populations reproduced and matured fruit beyond the limit, suggesting that if individuals dispersed beyond the limit that populations would establish. The species’ abrupt distributional limit also did not correspond to an abrupt shift in ecological conditions, despite the association of fitness with plant community and microhabitat variables. Overall, ecological tolerances to fitness or niche-based explanations to range limits do not adequately describe the distributions of either species. Constraints on dispersal rate, the influence of anthropogenic factors on habitat dispersion and limited genetic variability for fitness related traits are addressed. / Thesis (Ph.D, Biology) -- Queen's University, 2007-05-13 16:45:44.456

No description available.

Flammability limit is a most significant property of substances to ensure safety of chemical processes and fuel application. Although there are numerous flammability literature data available for pure substances, for fuel mixtures these are not always available. Especially, for fuel mixture storage, operation, and transportation, inert gas inerting and blanketing have been widely applied in chemical process industries while the related date are even more scarce. Lower and upper flammability limits of hydrocarbon mixtures in air with and without additional nitrogen were measured in this research. Typically, the fuel mixture lower flammability limit almost keeps constant at different contents of added nitrogen. The fuel mixture upper flammability limit approximately linearly varies with the added nitrogen except mixtures containing ethylene. The minimum added nitrogen concentration at which lower flammability limit and upper flammability limit merge together is the minimum inerting concentration for nitrogen, roughly falling into the range of 45 plus/minus 10 vol % for all the tested hydrocarbon mixtures. Numerical analysis of inert gas dilution effect on lower flammability limit and upper flammability limit was conducted by introducing the parameter of inert gas dilution coefficient. Fuel mixture flammability limit can be quantitatively characterized using inert gas dilution coefficient plus the original Le Chatelier's law or modified Le Chatelier's law. An extended application of calculated adiabatic flame temperature modeling was proposed to predict fuel mixture flammability limits at different inert gas loading. The modeling lower flammability limit results can represent experimental data well except the flammability nose zone close to minimum inerting concentration. Le Chatelier's law is a well-recognized mixing rule for fuel mixture flammability limit estimation. Its application, unfortunately, is limited to lower flammability limit for accurate purpose. Here, firstly a detailed derivation was conducted on lower flammability limit to shed a light on the inherent principle residing in this rule, and then its application was evaluated at non-ambient conditions, as well as fuel mixture diluted with inert gases and varied oxygen concentrations. Results showed that this law can be extended to all these conditions.

Thesis (MEng(TransportSystemsEng))--University of South Australia, 2004.

Thesis (MEng(TransportSystemsEng))--University of South Australia, 2004.

Thesis (MEng(TransportSystemsEng))--University of South Australia, 2004.

Thesis (M.App.Sc.) - Carleton University, 2006. / Includes bibliographical references (p. 144-152). Also available in electronic format on the Internet.

Thesis (Ph. D.)--Civil and Environmental Engineering, Georgia Institute of Technology, 2006. / Dr. William Bachman, Committee Member ; Dr. Peter P. Parsonson, Committee Member ; Dr. Kwok-Leung Tsui, Committee Member ; Dr. John D. Leonard II, Committee Member ; Dr. Karen Dixon, Committee Chair.