Modeling and analysis of complex structural-acoustic systems

Halliday, Peter John The University of Michigan 2000 해외박사(DDOD)

소속기관이 구독 중이 아닌 경우 오후 4시부터 익일 오전 9시까지 원문보기가 가능합니다.

Techniques are developed for modeling and analyzing the vibration response of complex structural-acoustic systems. A novel application of Lagrange multipliers to couple domains modeled independently with linear elasto-dynamic and reduced-order theories is presented. This method is developed from a variational formulation of the continuous problem and is easily implemented within a finite element code. Applications include modeling of cracks, holes, and junctions within a frame-like structure. Simulations using this method compare well with a full elasto-dynamic discretizations and existing methods for modeling such problems. In an experimental context, it is desirable to have a robust, flexible method for analyzing wave phenomena along a structure and in the surrounding fluid. A general framework is developed for determining the underlying parameters of general signal models through the application of maximum likelihood estimation theory for functions whose variables separate. This method extends previous work in sinusoidal and exponential estimation to include models with other functional bases, such as exponential functions with non-constant amplitudes and Bessel functions. Non-uniform spatial sampling is also possible with this technique. The maximum likelihood method is applied to the identification of wave components along one-dimensional structural elements. Results are given which demonstrate the viability and accuracy of the technique estimating exponential and Bessel function model parameters from noisy simulation data. Algorithms for determining material properties and power flow in vibrating structures are presented. New techniques are achieved by synthesizing wave component identification methods with new methods targeted towards material property and structural intensity estimation. The effectiveness of this nonlinear least-squares approach is investigated through laboratory and numerical experiments on a non-uniform structure, yielding guidelines for spatial sampling and the effects of noise. The study of harmonically driven <italic>in vacuo</italic> and fluid-loaded T-beams with various joint configurations is presented to demonstrate the ability of these modeling and analysis techniques to investigate complex structures. Numerical experiments are performed which investigate wave propagation in multiply connected beams, transmission of energy through a complex joint, power dissipation in a structure, and the effect of fluid loading on both wave propagation and energy dissipation.

Choreography as curriculum and knowing in education

Halliday, Christina Arija York University (Canada) 2002 해외박사(DDOD)

소속기관이 구독 중이 아닌 경우 오후 4시부터 익일 오전 9시까지 원문보기가 가능합니다.

My dissertation draws on phenomenological and post-structural approaches to dance, art, the body, curriculum, and learning theory to examine selected examples of artistic dance as curricula and epistemologies resistant to normative understandings of knowing, learning, and representation in education and education research. The term ‘choreography’ literally means ‘dance writing.’ In my dissertation I draw on this definition of choreography as ‘body discourse’ to perform a figuration or post-structural writing and research practice in education. Working within this methodological framework, I characterize examples of dance performance as choreography and define my orientation to these choreographies as parallel to the position of choreographer. Exploring four choreographies as my own curricula, Bill T. Jones's “Still/Here,” Peggy Baker's “a true story,” Margie Gillis's “Nothing Clings to You,” and contact improvisation dance, I examine each as an epistemological theory that insists on the presence of the body in experience, knowing, and representation. I argue that this insistence brings into relief the complementarity, rather than duality, of the following categories: body and mind, subject and object, the ‘real’ and representation, and theory and practice. Further, I perform these choreographies as epistemologies through an articulation of my own responses to the dance pieces. Here I draw on my experiences of mothering as evoking a similar kind of knowing. Hermeneutic phenomenology, as it has been understood and written about by Maurice Merleau-Ponty and Martin Heidegger in particular, is my language for describing choreography as epistemology in my dissertation. I draw on Merleau-Ponty's conception of the body as the ‘instrument of comprehension’ and ‘absolute source’ of knowledge and knowing to illustrate how choreography theorizes and puts into theory and practice the body in experience, knowing, and representation.

The relationship between exposure to community violence and violent behavior in the social ecologies of incarcerated adolescents

Halliday, Colleen Anita University of California, Los Angeles 1999 해외박사(DDOD)

소속기관이 구독 중이 아닌 경우 오후 4시부터 익일 오전 9시까지 원문보기가 가능합니다.

There is great overlap in the adolescents engaged in violent behavior and those exposed to community violence. Much psychological inquiry has focused on understanding the contributions that exposure to urban violence make to aggressive and violent behavior among youth, but the other ways in which these variables may be related have been overlooked. This study compared four alternate models of the manner in which violence exposure and violent behavior are related within the social ecologies of incarcerated inner city adolescents. The first model involved looking at violent behavior as a consequence of community violence exposure. The second model examined the degree to which engaging in violent behavior places one at risk for exposure to community violence. The third model examined the degree to which both violence exposure and violent behavior were consequences of common antecedents. The final model examined whether violence exposure and violent behavior were related because they were components of a syndrome of violence related outcomes. 277 adolescent offenders were interviewed to assess family, neighborhood, cognitive, and peer factors, as well as violent behavior and community violence exposure. Archival data was collected about arrests histories, and census data was used to measure neighborhood characteristics. The hypothesized models were tested using structural equation models. Results suggest that the best way to understand the association between community violence exposure and violent behavior is to consider both as manifestations of a general vulnerability towards violence.

Such is Furphy: Half bushman, half bookworm (Joseph Furphy, Australia)

Halliday, Laura Southern Illinois University at Carbondale 2005 해외박사(DDOD)

소속기관이 구독 중이 아닌 경우 오후 4시부터 익일 오전 9시까지 원문보기가 가능합니다.

This dissertation is an examination of the works of Joseph Furphy, an Australian writer of Irish ancestry. Australia, like so many former colonies, has made a long and difficult journey towards creating and claiming a literary canon unique to itself. Joseph Furphy is a little-known but important figure of that canon. The first focus area of the study is the complex relationship between Joseph Furphy and his narrator, Tom Collins. Tom Collins is Furphy's pen name, and it is difficult to clarify in Furphy's work where fiction leaves off and biography begins. Tom's uses of intertextual references and pyrotechnic language makes decoding Furphy's most important novel, Such is Life , even more difficult, a feat which is compounded by Tom's unreliability as a narrator. The second focus of the study is the "Irishness" of Such is Life . Furphy makes use of intertextual connections to Irish works such as Castle Rackrent and The Wild Irish Girl. He also uses Irish emigrant characters prominently in the novel, and address Irish Issues such as Orangeism in Ireland and Australia as well as religious division. The third area of concentration expands on Furphy's examination of the Irish to include his treatment of several Nationalist characters, including Scottish, British, Aboriginal, and English characterizations and stereotypes. Finally, the study concludes with an examination of thematic issues and textual strategies in Joseph Furphy's two other novels, published posthumously. Through this overview, Furphy's importance to the Australian literary canon is reexamined with emphasis on his attempt through fiction to assimilate new colonists of disparate backgrounds into citizens of their adopted home. Critics have claimed that Joseph Furphy is the "James Joyce of Australia" in that he attempts to create a vision of Australia which is free-standing and removed from Europe and its artistic domination. His work pushes against the traditional English romantic novel's conventions and restrictions, and in his own voice, articulates one voice for Australia.

Essays on the economics of health and migration (El Salvador, United States)

Halliday, Timothy James Princeton University 2004 해외박사(DDOD)

소속기관이 구독 중이 아닌 경우 오후 4시부터 익일 오전 9시까지 원문보기가 가능합니다.

The first chapter of this dissertation investigates the dynamics of health. We estimate a simple model describing health dynamics that allows for heterogeneous first order state dependence. We find evidence of state dependence in health. This finding suggests that health is inertial at the individual level. We find that the occupancy of a health state today affects future health for approximately five years. In addition, we find that health dynamics are strongly tied to socioeconomic status; we find a gradient in the persistence of pre-existing illness and we find a steeper gradient in the onset of new illness. Our findings are informative of the nature of the gradient in individual health dynamics. The second chapter considers the use of migration between the US and El Salvador as a means of self-insurance for rural Salvadoran households. We show that households responded to adverse agricultural conditions in El Salvador by allocating more members to the US. In addition, we show that households responded to damage sustained during the 2001 earthquakes by retaining household members in El Salvador. These findings are consistent with a model in which agricultural shocks lower returns in El Salvador, thereby, inducing northward migration and housing damage raises the marginal utility of housing in El Salvador, thereby, creating exigencies at home which stunt northward migration. Finally, the effects of the earthquakes were independent of household wealth suggesting that the earthquakes affected migration through a channel other than liquidity constraints. The final chapter of this dissertation tests the proposition that migrants are healthier than non-migrants. Our findings are supportive of this proposition and, thus, suggest that health induces selection in migration. In addition, we find evidence of a graded relationship between health and mobility so that good health is more closely associated with higher degrees of mobility than it is with lower degrees of mobility. Our results suggest that healthier people are better able to relocate to areas with higher wages and, thus, suggest a mechanism that would generate a causal effect of health on earnings. Finally, we show how non-random durations in the panel can create a selection bias.

How aspirations are formed and challenged in the transition to adulthood and implications for adult well-being

Hardie, Jessica Halliday The University of North Carolina at Chapel Hill 2009 해외박사(DDOD)

소속기관이 구독 중이 아닌 경우 오후 4시부터 익일 오전 9시까지 원문보기가 가능합니다.

Aspirations play a primary role in linking social class background to later attainment. Planful adolescents who formulate ambitious educational and occupational goals are more likely to succeed than those who hold modest expectations. Yet we know little about the process by which young people choose and develop aspirations or the barriers they face in attempting to achieve these goals. This dissertation aims to fill this gap, by asking how structural factors shape the choices young people make regarding their educational and occupational futures, how the ability to follow through on these choices is distributed, and how failing to meet one's chosen goals may impact individuals' job satisfaction and psychological well-being. The first chapter uses in-depth interviews with 61 junior and senior high school girls to show how social class shapes educational and occupational aspirations and plans through the availability and use of social networks. These interviews reveal that middle class adolescents are embedded in resource-rich social networks that facilitate high educational and occupational attainment while limited social ties, family instability, and parental disengagement produce disadvantages for working class and poor youth. The second chapter uses survey data from the National Longitudinal Study of Youth 1979 (NLSY79) and National Educational Longitudinal Study (NELS) to explore the relationship between events in the transition to adulthood and fulfillment of one's educational and occupational expectations. Findings reveal that the order and timing of family formation and dissolution events can disrupt young people's paths to attainment in early adulthood. The final chapter uses NLSY79 and NELS datasets to test the relationship between falling short of one's expectations and emotional and psychological outcomes in early adulthood. Results indicate that occupational expectations can serve as baseline standard with which to judge later accomplishments---falling short of these goals leads to lower emotional and psychological well-being in adulthood. These findings support the claims of relative deprivation theory, which argues that dissatisfaction arises from the gap between what one has and what one wants.

The high salt marsh ecotone: A study of its structure and function and the influence of grazing and nitrogen addition on its community dynamics

Traut, Bibit Halliday University of California, Davis 2003 해외박사(DDOD)

소속기관이 구독 중이 아닌 경우 오후 4시부터 익일 오전 9시까지 원문보기가 가능합니다.

Ecotones are important landscape features, often harboring rich faunal and floral assemblages and serving as filters for materials across the landscape. The goal of my research was to describe the structure and function of the high salt marsh ecotone and to evaluate the influences of grazing and nitrogen addition. My objectives were to answer the following questions: (1) can a community of high marsh plants be identified? Are there any plants that indicate it? (2) What environmental conditions best describe the high marsh? (3) Does the high marsh function as an ecotone by serving as a place of increased nutrients, especially nitrogen, and increased diversity in plant and spider richness? (4) Are marshes that are dominated by salt grass, <italic>Distichlis spicata</italic>, structured by grazers: either directly by herbivory or indirectly by excess nitrogen input?. To answer the first 3 questions I conducted a survey of 12 marshes in the Pt. Reyes area of California. To address the last question, I conducted manipulative studies to test the hypotheses: (1) grazer exclusion will result in increased vegetation with species rich, homogeneous communities; and (2) <italic>Distichlis spicata</italic> is a better competitor for nitrogen and will dominate in N-addition plots. The high marsh appears to be a unique ecotonal community responding to elevational, salinity, and moisture gradients and harboring increased pools of nitrogen. The ecotone had increased plant and spider richness as well. Plant richness was greatest in wider areas of the high marsh, and spider richness was enhanced as vegetation complexity increased. Excluding herbivory in these nutrient-limited high marsh communities increased vegetation cover and enhanced diversity. Grazing in high marsh shifts plant community structure, in support of the grazer reversal hypothesis of reduced diversity in resource-limited ecosystems. There was no significant effect on spider and ant diversity. Nitrogen addition did not shift dominance in plots towards <italic>Distichlis spicata</italic>, as predicted, and plant richness and evenness did not differ significantly between treatments. Although several species thrived (e.g. <italic> Salicornia, Distichlis, Triglochin</italic>), competitive exclusion did not occur. Instead, nitrogen addition increased overall biomass and tissue nitrogen accumulation, especially in <italic>Triglochin concinna</italic> and <italic> Jaumea carnosa</italic>.