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Acoustic characterization of orifices and perforated liners with flow and high-level acoustic excitationZhou, Lin January 2015 (has links)
This thesis is motivated by the need for noise control in aircraft engine with orifices and perforated liner. The presence of high-level acoustic excitation, different flow situations either bias flow, grazing flow or any combination in the aircraft engine, makes the acoustic behavior complex due to the interaction between sound and flow over the lined wall. Both systematic acoustic prediction of aircraft engines and liner optimization necessitate progress in impedance measurement methods by including the effect of the complex flow situations. The aim of the present thesis is to experimentally study the change in acoustic properties of orifices and perforated liners under bias or grazing flow. In order to study the effect of different combinations of bias flow and high-level acoustic excitation, an in-duct orifice has been investigated with finely controlled acoustic excitation levels and bias flow speeds. This provides a detailed study of the transition from cases when high-level acoustic excitation causes flow reversal in the orifice to cases when the bias flow maintains the flow direction. Nonlinear impedance is measured and compared, and a scattering matrix and its eigenvalues are investigated to study the potentiality of acoustic energy dissipation or production. A harmonic method is proposed for modelling the impedance, especially the resistance, which captures the change in impedance results at low frequencies compared with experimental results. The presence of grazing flow can increase the resistance of acoustic liners and shift their resonator frequency. So-called impedance eduction technology has been widely studied during the past decades, but with a limited confidence due to the interaction of grazing flow and acoustic waves. A comparison has been performed with different test rigs and methods from the German Aerospace Center (DLR). Numerical work has been performed to investigate the effect of shear flow and viscosity. Our study indicates that the impedance eduction process should be consistent with that of the code of wave propagation computation, for example with the same assumption regarding shear flow and viscosity. A systematic analysis for measurement uncertainties is proposed in order to understand the essentials for data quality assessment and model validation. The idea of using different Mach numbers for wave dispersion and in the Ingard-Myers boundary condition has been tested regarding their effect on impedance eduction. In conclusion, a local Mach number based on friction velocity is introduced and validated using both our own experimental results and those of previous studies. / <p>QC 20150522</p>
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City and regional planning software in context : a rating framework for Planning Support SystemsPhelan, Chad Maclay 17 August 2010 (has links)
The difficulty of projecting ecological impacts, as well as the increasing familiarity of planners
with Geographical Information Systems and other software technology has led to an increase in the use of Planning Support Systems (PSS) by city and regional planners. Due to their newness
and rapid development, there is, of yet, a lack of a comprehensive peer-reviewed literature on the
design and implementation of these systems. This thesis proposes and applies a rating framework
for PSS in order to facilitate accessibility to and critical investigation of PSS. The rating
framework’s criteria are based on the “seven sins” of comprehensive land use models identified by Douglass Lee’s 1973 article “Requiem for Large-Scale Models." / text
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Identification of Predictors of Success in Individualized Computer CoursesRussell, John D. (John David), 1938- 08 1900 (has links)
This study provides a rationale for advising students on whether to enroll in individualized/self-paced computer courses. It identifies seven factors that have a significant correlation with success in an individualized computer course. The sample comprises all the students enrolled in individualized computer courses at Lee College, Baytown, Texas in the spring semester of 1988. Students completed a survey to determine whether they had previous computer experiences, whether they operated with a level of introvert personality characteristics, and whether the individualized computer course was their first choice. Students completed a learning style inventory and a score was determined using the items relating to individualized computer studies. Data collected in the Lee College records office included high school percentile rank, standardized reading score, standardized mathematics score, college hours completed, course withdrawals, and age. The following seven factors were shown by the data to have a significant correlation with a final grade (in order of decreasing significance): (a) learning style inventory, (b) high school percentile, (c) standardized mathematics score, (d) standardized reading score, (e) previous computer experience, (f) number of college hours, and (g) age. The following three factors were shown by the data to have no significant correlation with a final grade: (a) course withdrawals, (b) degree of personality introversion, and (c) the individualized computer course as first choice. The findings substantiate the hypothesis that success in an individualized computer course might be attributed to certain factors, and once identified, these factors can be used in advising students. Advisors should use as many of the seven factors (identified as significant), as possible in helping students choose between individualized and traditional computer courses.
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Imagem retórica e imagem plástica: relações verbovisuais na obra Paranoia de Roberto Piva / Rhetorical image and artistic image: verb-visual relations in Paranoia, by Roberto PivaMariana Outeiro da Silveira, Mariana Outeiro da Silveira 30 November 2016 (has links)
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Previous issue date: 2016-11-30 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / This dissertation aims to investigate the connections between poetic and visual texts in Paranoia, written by Roberto Piva, which incorporate a photographic intervention by Wesley Duke Lee. The corpus of this study is Paranoia’s illustrated edition (2000), organized by the artists themselves and also by the notorious publisher Massao Ohno. Theoretically, this research is based on the concept of intersemiotic translation, originally formulated by Roman Jakobson and later developed by Julio Plaza, and considers studies that have innovative approaches related to this topic. Expertise about Surrealism and Beat poetry also interests our research, especially ideas presented by Andre Breton, Walter Benjamin and Allen Ginsberg. Methodologically, this study has the intention to investigate bibliography and documents, the latter related to the Wesley Duke Lee’s archives. The relevance of this research is tied to the current recognition of Piva’s work by scholars and critics, who have considered him a representative of the late historical Brazilian avant-gardes from the middle of the XX century. Due to its photographic intervention, it is necessary to address Paranoia in a wide-ranging area, outside the Literary field / A presente dissertação visa investigar as relações entre texto poético e texto visual na versão da obra Paranoia de Roberto Piva que incorpora a intervenção fotográfica do artista plástico Wesley Duke Lee. O corpus da pesquisa compreende a edição ilustrada de 2000 de Paranoia, organizada pelos artistas em questão e também pelo célebre editor Massao Ohno. Teoricamente, a pesquisa faz apelo ao conceito de tradução intersemiótica, tal como originalmente formulado por Roman Jakobson e posteriormente desenvolvido por Julio Plaza, e aos estudos em torno destas abordagens inovadoras. Dados os estilos vanguardistas dos artistas em questão, interessam-nos também expertises sobre o surrealismo e a poesia beat, a exemplo daquelas propostas por André Breton, Walter Benjamin e Allen Ginsberg. Metodologicamente, trata-se de perquirição bibliográfica e documental, esta última envolvendo o acervo de Wesley Duke Lee. A relevância desta pesquisa prende-se ao reconhecimento atual da obra de Piva, no âmbito da universidade e da crítica, a sua especial maneira de representar as vanguardas históricas brasileiras tardias dos meados do século XX e, dada sua recriação fotográfica, à necessidade de abordá-la de modo mais abrangente, fora do campo específico das Letras
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Revised entries: Bill Clifton, Wilma Lee & Stoney Cooper, Tom T. Hall and Dixie, the Osborne BrothersBidgood, Lee 01 January 2013 (has links)
Book Summary: The Grove Dictionary of American Music, second edition is the largest, most comprehensive reference publication on American Music. Twenty-five years ago, the four volumes of the first edition of the dictionary initiated a great expansion in American music scholarship. This second edition reflects the growth in scholarship the first edition initiated. At eight volumes, it provides greatly expanded coverage, particularly in the areas of popular music, cities and regions, musical theater, opera, concert music, and music technology, as well as the musical traditions of many ethnic and cultural groups.
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A Guide to Teaching Materials for Industrial ArtsBlowers, Russell 01 July 1949 (has links)
This study, "A Guide to Teaching Materials for Industrial Arts," was prompted by the fact that the writer is concerned with teaching aids available to the shop teacher in the field. Several years teaching has brought the writer face to face with the problem of supplementary teaching materials. Knowing that complete listings of teaching aids for the teacher are not available, the writer determined to make available such a listing which would be most beneficial to the shop teachers.
The problem is fourfold: To catalogue industrial arts teaching aids. To determine the extent of the educational departments in the industrial firms. To determine the free and low cost teaching aids made available for the industrial arts teacher. To educate the teacher and the pupil as to the materials available and thus educate them to better buying.
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Ignorance v. Innocence : Go Set a Watchman’s Case against the Hegemony of To Kill a Mockingbird / Ignorans mot Oskyldighet : Go Set a Watchmans fall mot To Kill a Mockingbirds HegemoniGustafsson, Thän January 2019 (has links)
This paper takes a cultural materialist approach in analyzing the hegemonic purpose of using Harper Lee’s To Kill a Mockingbird in American education. Ideas from critical race theory and Lee’s second novel, Go Set a Watchman, are used to reveal obfuscated aspects of Mockingbird’s narrative. These aspects have been repurposed to fit a Eurocentric palate, and have let the book achieve success under the guise of being a progressive and multiculturalist work. Mockingbird’s narration, marked by childlike innocence, has been used to obfuscate Eurocentric ignorance of racial and economic inequality. The text has also been used to divert blame from those in power onto those oppressed by a hegemonic system. Racism is in Mockingbird inaccurately described as an individual moral issue, rather than a system of discrimination which is deeply ingrained in every aspect of U.S. society. The liberal moderate ideology which informs Atticus character has historically been ignored due to his unquestionable, near-mythical position as a moral role model. The paper finds that Mockingbird has been used as part of a greater Eurocentric narrative which positions the Civil Rights Movement as a white movement of moral improvement.
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Comparisons of Snow Deposition, Soil Temperature, Matric Potential and Quasi-friction Velocity Between a Windward Site and a Lee Shelter in a Cold DesertNeuber, Harvey L. 01 May 1984 (has links)
Regimes of snow depth, soil temperature, soil matric potential and quasi-friction velocity in a windward site and a lee shelter were examined. The differences were analyzed from a biological perspective to .characterize each location in terms of site favorability to plant growth. The chronology of wind and precipitation events was investigated.
Snow depth was measured with a system of stakes arranged around and in the interior of a rectangular plot encompassing both a windward site and a lee shelter. Soil temperature, soil matric potential and water potential were measured along a transect which originated in the windward site and terminated in the lee shelter. Soil temperature and water potential were measured by thermocouple psychrometer. Mattie potentials was determined by the pressure-plate method. The regimes of quasi-friction velocity at both ends of the transect were determined by the logarithmic profile method, invoking similarity theory. Wind speed and temperature were measured at two heights in each site. A computer program was used to search the wind and precipitation records and ·categorize and sun the precipitation events by wind direction.
The lee shelter exhibited tendencies toward theoretical optima of site favorability. The horizontal distribution of snow maxima was found. to be a function of wind direction at the time of each precipitation event as well as the interaction of wind and the topographical features.
Snow was observed to accumulate to a greater depth in the lee shelter than in the windward site. Mean soil temperature over the study period was 8.5° C in the lee shelter while the windward site was 8.0° C. Soil temperature in the lee shelter was never observed to go below 0° C under a snowpack. The range of soil matric potential in the lee shelter was found to be about 14 atm at a depth of 20 cm and about 17 atm at a depth of 50 cm over the summer season. In the windward site the range of soil matric potential was approximately 30 atm at a depth of 20 cm and about 21 atm at a the 50 cm depth over the same period. The lee shelter exhibited lower (less negative) matric potentials than the windward site. These results were not corroborated by the measurement of water potential by thermocouple psychrometers. In the layer from 1.5 to 4.1 m, the mean quasi-friction velocity in the lee shelter was 39 cm s-1, favoring snow deposition there over the windward site where the mean friction velocity was 21 cm s-l. In the 0 m to 1. 5 m layer, mean friction velocity in the windward site was found to be 55 cm s-1.while the lee shelter mean was 48 cm s-1. These results indicate a distinct seperation of flow downwind of the windward site where the lee shelter resides in the turbulent wake of the windward site.
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Forme normale tournante des tressesFromentin, Jean 30 June 2009 (has links) (PDF)
Une tresse est une classe d'équivalence de mots de tresse. Diverses formes normales sur les tresses ont été décrites dans la littérature, c'est-à-dire, divers moyens de sélection, pour toute tresse, d'un mot de tresse distingué la représentant. Définie de façon naturelle sur les monoïdes de tresses de Birman-Ko-Lee (ou duaux), la forme normale tournante peut être étendue au groupe de tresses tout entier. Ici, nous donnons des contraintes de nature combinatoire satisfaites par cette nouvelle forme normale. Nous en obtenons ainsi une caractérisation et montrons que l'ensemble des formes normales tournantes des tresses duales constitue un langage régulier.<br /><br />Un résultat de P. Dehornoy (1992) affirme que toute tresse non triviale admet un représentant sigma-défini. Ce résultat est à la base de la construction de l'ordre des tresses. A l'aide de la forme normale tournante et de ses propriétés, nous montrons que toute tresse admet un représentant sigma-défini de longueur quasi-géodésique, ce qui résout une question ouverte depuis une quinzaine d'années. <br /><br />Un résultat de R. Laver montre que les monoïdes de Birman-Ko-Lee munis de l'ordre des tresses sont bien ordonnés mais laisse ouvert la détermination de leurs longueurs.<br />A l'aide de la forme normale tournante, nous obtenons une caractérisation de l'ordre des tresses sur le monoïde de Birman-ko-Lee à n brins à partir de sa restriction sur celui à (n-1) brins. Une conséquence de ce résultat est une nouvelle démonstration du résultat de R. Laver ainsi que la détermination de la longueur des monoïdes de tresses duaux munis de l'ordre des tresses.
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Dixy Lee Ray, marine biology, and the public understanding of science in the United States (1930-1970)Ellis, Erik 21 November 2005 (has links)
This dissertation focuses on the life of Dixy Lee Ray as it examines important
developments in marine biology and biological oceanography during the mid twentieth
century. In addition, Ray's key involvement in the public understanding of science
movement of the 1950s and 1960s provides a larger social and cultural context for
studying and analyzing scientists' motivations during the period of the early Cold War
in the United States. The dissertation is informed throughout by the notion that science is
a deeply embedded aspect of Western culture. To understand American science and
society in the mid twentieth century it is instructive, then, to analyze individuals who
were seen as influential and who reflected widely held cultural values at that time. Dixy
Lee Ray was one of those individuals. Yet, instead of remaining a prominent and
enduring figure in American history, she has disappeared rapidly from historical memory,
and especially from the history of science. It is this very characteristic of reflecting her
time, rather than possessing a timeless appeal, that makes Ray an effective historical
guide into the recent past. Her career brings into focus some of the significant ways in
which American science and society shifted over the course of the Cold War.
Beginning with Ray's early life in West Coast society of the 1920s and 1930s,
this study traces Ray's formal education, her entry into the professional ranks of marine
biology and the crucial role she played in broadening the scope of biological
oceanography in the early 1960s. The dissertation then analyzes Ray's efforts in public
science education, through educational television, at the science and technology themed
Seattle World's Fair, and finally in her leadership of the Pacific Science Center. I argue
that Ray was ideally suited to promote a dominant conception of a socially useful and
instrumental form of science that lay at the core of the public understanding of science
through the 1960s. These efforts in the public understanding of science reflected a broad
endeavor among scientists to spread knowledge about and values of modern science from
elite American society to a broader public. The dissertation concludes with a short
examination of Ray's neutral gendered identity which, considered within the largely
masculine context of science, played a significantly role in the successes of her
professional career. / Graduation date: 2006
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