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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
231

Fast Adaptive Numerical Methods for High Frequency Waves and Interface Tracking

Popovic, Jelena January 2012 (has links)
The main focus of this thesis is on fast numerical methods, where adaptivity is an important mechanism to lowering the methods' complexity. The application of the methods are in the areas of wireless communication, antenna design, radar signature computation, noise prediction, medical ultrasonography, crystal growth, flame propagation, wave propagation, seismology, geometrical optics and image processing.   We first consider high frequency wave propagation problems with a variable speed function in one dimension, modeled by the Helmholtz equation. One significant difficulty of standard numerical methods for such problems is that the wave length is very short compared to the computational domain and many discretization points are needed to resolve the solution. The computational cost, thus grows algebraically with the frequency w. For scattering problems with impenetrable scatterer in homogeneous media, new methods have recently been derived with a provably lower cost in terms of w. In this thesis, we suggest and analyze a fast numerical method for the one dimensional Helmholtz equation with variable speed function (variable media) that is based on wave-splitting. The Helmholtz equation is split into two one-way wave equations which are then solved iteratively for a given tolerance. We show rigorously that the algorithm is convergent, and that the computational cost depends only weakly on the frequency for fixed accuracy.  We next consider interface tracking problems where the interface moves by a velocity field that does not depend on the interface itself. We derive fast adaptive  numerical methods for such problems. Adaptivity makes methods robust in the sense that they can handle a large class of problems, including problems with expanding interface and problems where the interface has corners. They are based on a multiresolution representation of the interface, i.e. the interface is represented hierarchically by wavelet vectors corresponding to increasingly detailed meshes. The complexity of standard numerical methods for interface tracking, where the interface is described by marker points, is O(N/dt), where N is the number of marker points on the interface and dt is the time step. The methods that we develop in this thesis have O(dt^(-1)log N) computational cost for the same order of accuracy in dt. In the adaptive version, the cost is O(tol^(-1/p)log N), where tol is some given tolerance and p is the order of the numerical method for ordinary differential equations that is used for time advection of the interface.   Finally, we consider time-dependent Hamilton-Jacobi equations with convex Hamiltonians. We suggest a numerical method that is computationally efficient and accurate. It is based on a reformulation of the equation as a front tracking problem, which is solved with the fast interface tracking methods together with a post-processing step.  The complexity of standard numerical methods for such problems is O(dt^(-(d+1))) in d dimensions, where dt is the time step. The complexity of our method is reduced to O(dt^(-d)|log dt|) or even to O(dt^(-d)). / <p>QC 20121116</p>
232

Statistical energy analysis and variational principles for the prediction of sound transmission in multilayered structures

Barbagallo, Mathias January 2013 (has links)
Multilayered structures have many application in industry and society: they have peculiar properties and serve a variety of purposes, like structural support, thermal insulation, vibrational and acoustic isolation. This thesis concerns the prediction of sound transmission in multilayered structures. Two problems are herein investigated: the transmission of energy through structures and the transmission of energy along structures. The focus of the analysis is on the mid to high frequency range. To predict sound transmission in these structures, statistical energy analysis (SEA) is used.SEA models are devised for the prediction of the sound reduction index for two kinds of multilayered structures, double-walls used in buildings and trim-panels in vehicles; the double-walls comprise an air cavity in between flat plasterboard or glass plates, whereas the trim-panels a porous layer in between curved aluminium and rubber layers. The SEA models are based upon the wave-types carrying energy. The novelty in these SEAs is an element describing the waves in the air cavity, or in the porous layer, fully coupled to the mass-impeded external layers. Compared to measurements, the proposed SEA performs well: for double-walls, it performs better than previous models; for trim-panels, it is an original result. The parameters of the new SEA element, such as modal density, are derived from the coupling equations describing the fully coupled waves. For double-walls, these equations are derived via Newton's laws. For trim-panels, a variational approach based upon a modified Hamilton's principle valid for non-conservative systems is preferred, because it is a powerful machinery for deriving equations of motion and coupling conditions of a medium as complex as the porous layer. The modified Hamilton's principle for non-conservative systems is based upon a self-adjoint functional analogous to the Lagrangian, inspired by Morse and Feshbach's construction. A self-adjoint variational principle for Biot's equations in the displacement formulation is devised. An equivalent mixed formulation is obtained changing the coordinates of the displacement formulation via Lagrange multipliers. From this mixed formulation, the Lagrangian for a porous material with a limp frame is derived, which yields the continuity of the total displacement of the porous layer. Lagrange multipliers help to obtain the correct coupling functionals between a porous material and a solid. The Lagrange multipliers introducing the continuity of the frame and the solid displacements equal the traction of the in-vacuo frame, thus disappearing if the latter is limp. Measurements to gather material parameters for a Biot model of the porous layer have been conducted.The effects of spatial energy decay in the transmission along structures predicted by SEA is studied: a major effect is the increased relevance of indirect coupling loss factors between SEA elements. This may jeopardize the usefulness of SEA at higher frequencies. / <p>QC 20130218</p>
233

Alice Hamilton: The Making of a Feminist-Pragmatist Rhetor

McCoy, Vicki J. 12 January 2006 (has links)
ABSTRACT Dr. Alice Hamilton (1869-1970), the leading American figure in industrial medicine during the early to mid-1900s, left behind a body of rhetoric that is important in the history of American feminist discourse and American public address. Her discourse is the exemplary of feminist-pragmatist rhetoric, a genre of cross-gender communication developed by New Women associated with Hull House and the University of Chicago between 1892 and 1918. Hamilton’s rhetoric illuminates a key event in the history of the American rhetorical tradition—the emergence of the modern woman from her late-Victorian beginnings through her Progressive self-transformation. This study is approached as a rhetorical biography. It tracks Hamilton’s evolution from “reticent scientist” to outspoken feminist-pragmatist by examining family, educational, peer and social influences on her development; and through critical analysis of her speeches, technical writing, books, and popular and specialty magazine articles over a 36-year period, from 1907 to 1943.
234

Allen Hamilton, the evolution of a frontier capitalist

Wetmore, Allyn C. 03 June 2011 (has links)
This study examines a frontier businessman and the evolution of his business enterprises in conjunction with the emergence of northern Indiana from its frontier period to the time that it became a settled agricultural region with strong ties to the national economy. The subject is Allen Hamilton, an Irish immigrant who settled in Fort Wayne, Indiana in 1823 and remained here until his death in 18514. Hamilton's involvement with the affairs of the state government, the Miami and Potawatomi Indians, retailing, land speculation, the promotion and construction of the Wabash and Erie Canal and numerous plank road and railroad projects, the fur trade and the Indian trade, the second State Bank of Indiana and the creation of the Hamilton ink involved him deeply in the economic development and the political affairs of Indiana and, to a lesser extent, of the North.This study of Hamilton's rise to wealth parallels the development of Indiana and is intertwined with it. At nearly all points in his career Hamilton achieved financial success by meeting the needs of the developing region. He functioned at first as a fur trade .end Indian trader, meeting the needs of the Indians as well as the large Eastern fur merchants. Toward the end of his career he was primarily a banker and promoter of internal improvements, serving both his own interests and those of the expanding white population of northern Indiana for credit and adequate transportation facilities.In order to compete successfully as a businessman, Hamilton found it necessary to become involved with the politics of the region and at times was himself a successful candidate for local and state offices. Generally, however, his political activities were confined to the support of influential men from northern Indiana, several of whom were his business partners. The ability to form judicious alliances which took advantage of both political influence and entrepreneurial talent was a chief factor of Hamilton's success. His business partnerships demonstrated the evolution of his activities and his partners included the most important men in that section of the state. These partnerships were flexible, allowing for significant alteration as new opportunities (such as the milling of wheat) presented themselves and older avenues to wealth (such as the fur trade) dried up. As Hamilton outgrew the older partnerships he created others that reflected not only the need for a different type of expertise in his partner but also his own changed economic, social and political situation. One of the consistencies of Hamilton's partnerships was their diversification which made them more fluid in nature and more capable of capitalizing on new opportunities.Hamilton's rise to wealth was significant not only to himself. His wealthy Irish origins had set for him a model to which the wealthy should aspire. Correspondingly, he was a social leader in Fort Wayne and nurtured in his offspring a respect for the highest of goals in education and civic responsibility. He was a patrician and a symbol not only of the opportunities of the West, but also of the fact that the West was far from being an area inhabited by social equals. Indeed, Hamilton's extensive commitment to land speculation was more than simply a means ofachieving wealth. The possession of large tracts of land symbolized, for Hamilton, the recreation of his family's former status in Ireland, powerfully augmenting the traditional status gained through land ownership in the United States.Through Allen Hamilton one may view not only the development of Indiana in the second quarter of the nineteenth century, but also a pattern of economic maturation that was often experienced in areas far to the east and west of the state.
235

An archaeological assessment of the Strawtown site and the immediate vicinity

Hixon, James Lee 03 June 2011 (has links)
This study is an assessment of the archaeological resources the Strawtown Site area in northeastern Hamilton County, _ndiana. Strawtown was an intensively occupied village during the Late woodland Period (Householder, personal communication, 1986) and appears closely related to the Bowen site (Dorwin, 1971:209).This thesis documents the Strawtown Site and associated :materials through background research and collection analysis; other sites in the immediate vicinity were identified through a systematic reconnaissance of a 555.24 acre sample area. This information was combined to test both Dorwin"s (1971) Oliver Phase settlement pattern and the Woodland settlement model proposed by Stephenson (1984).In light of the information that is available, Dorwin"s and Stephenson's models of a seasonal occupation of the river valley by Late Woodland groups was argued against in favor of a model which assumes permanent Late Woodland occupation of the river valley.Ball State UniversityMuncie, IN 47306
236

Study on optimal train movement for minimum energy consumption

Gkortzas, Panagiotis January 2013 (has links)
The presented thesis project is a study on train energy consumption calculation and optimal train driving strategies for minimum energy consumption. This study is divided into three parts; the first part is a proposed model for energy consumption calculation for trains based on driving resistances. The second part is a presentation of a method based on dynamic programming and the Hamilton-Jacobi-Bellman equation (Bellman’s backward approach) for obtaining optimal speed and control profiles leading to minimum energy consumption. The third part is a case study for a Bombardier Transportation case. It includes the presentation of a preliminary algorithm developed within this thesis project; an algorithm based on the HJB equation that can be further improved in order to be used online in real-time as an advisory system for train drivers.
237

The Gift of Policing: Understanding Image and Reciprocity

Moore, Sheldon Edward Scott Jay January 2009 (has links)
The Community Based Policing model has been adopted by the large majority of policing agencies as another tool on an officer’s duty belt that allows them to do their job more effectively and efficiently. The model is premised on the building and maintaining of relationships of the Police Service and the community it serves. The model argues that Services must ensure that the community is given a voice in the way police enforce the laws. The model encourages that the police and community work together in a partnership that is different from the traditional relationship shared between the two groups under the previous Professional Policing model. This working in partnership means that not only must the police become more open to the community providing direction in the way they do their job, but also that the community must take a more active role in the policing of their areas. This partnership could be considered an exchange of information from both the police and the community. As argued by Marcel Mauss in The Gift, relationships that are on-going and have elements of exchange have obligations. These obligations of giving, receiving and reciprocity ensure that the relationship between the groups is not only maintained, but strengthened. When one of these obligations is not met, however, there are often social consequences. This research attempts to understand the model of Community Based Policing in terms of how it is being applied by Canada’s second oldest police service, the Hamilton Police. With the model encouraging a relationship with the community, issues of gift exchange appear. Through interviews with staff of the Hamilton Police Service, as well as citizens from the community of Hamilton, how these obligations are being met, as well as the effectiveness of the model and its relation to Maussian theory of gift exchange are explored.
238

The Gift of Policing: Understanding Image and Reciprocity

Moore, Sheldon Edward Scott Jay January 2009 (has links)
The Community Based Policing model has been adopted by the large majority of policing agencies as another tool on an officer’s duty belt that allows them to do their job more effectively and efficiently. The model is premised on the building and maintaining of relationships of the Police Service and the community it serves. The model argues that Services must ensure that the community is given a voice in the way police enforce the laws. The model encourages that the police and community work together in a partnership that is different from the traditional relationship shared between the two groups under the previous Professional Policing model. This working in partnership means that not only must the police become more open to the community providing direction in the way they do their job, but also that the community must take a more active role in the policing of their areas. This partnership could be considered an exchange of information from both the police and the community. As argued by Marcel Mauss in The Gift, relationships that are on-going and have elements of exchange have obligations. These obligations of giving, receiving and reciprocity ensure that the relationship between the groups is not only maintained, but strengthened. When one of these obligations is not met, however, there are often social consequences. This research attempts to understand the model of Community Based Policing in terms of how it is being applied by Canada’s second oldest police service, the Hamilton Police. With the model encouraging a relationship with the community, issues of gift exchange appear. Through interviews with staff of the Hamilton Police Service, as well as citizens from the community of Hamilton, how these obligations are being met, as well as the effectiveness of the model and its relation to Maussian theory of gift exchange are explored.
239

The Transformative City

Slote, Kyle Douglas January 2011 (has links)
The issue of downtown revitalization has been much studied over the past several decades. However, much of the existing knowledge base pertains to our largest urban centres. This leaves a significant information gap with regards to mid-size cities. As a result, past renewal attempts in these cities have often been scaled down versions of what has worked in larger cities. In most cases, this has resulted in detrimental rather than reviving effects. The current trend in cities of all sizes is the implementation of Creative City Theory. This thesis seeks to study this trend and its specific relevance to the mid-size city. The scope of research will then build on the current theory by exploring the effects of well-designed public spaces and their ability to not only unleash the creative spirit but to revitalize the post-industrial mid-size city downtown. This information will then be applied to a design study for Hamilton, Ontario where failed renewal attempts have crippled the city’s downtown. The design will concentrate on Jackson Square (formerly known as Civic Square), a superblock within the very centre of downtown Hamilton. Through a redesign of Jackson Square, the thesis proposes to create a place that not only fosters creativity, but is once again meaningful and significant to Hamilton citizens. While the application of research to Hamilton is specific, the goal is to produce a body of work with principles that can be applied to any number of mid-size cities across the post-industrial world.
240

"In the Beginning Was the Word." The road towards a Speaking Subject in Jane Hamilton's The Book of Ruth

Jansdotter, Annika January 2004 (has links)
No description available.

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