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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.
1

On the theory of second-order soundfield microphone

Cotterell, Philip S. January 2002 (has links)
No description available.
2

On Stern‐Gerlach coincidence measurements and their application to Bell's theorem

Wennerström, Håkan, Westlund, Per-Olof January 2013 (has links)
We analyze a coincidence Stern-Gerlach measurement often discussed in connection with the derivation and illustration of Bell's theorem. The treatment is based on our recent analysis of the original Stern-Gerlach experiment (PCCP, 14, 1677‐1684 (2012)), where it is concluded that it is necessary to include a spin relaxation process to account for the experimental observations. We consider two limiting cases of a coincidence measurement using both an analytical and a numerical description. In on limit relaxation effects are neglected. In this case the correlation between the two spins present in the initial state is conserved during the passage through the magnets. However, at exit the z coordinate along the magnetic field gradient is randomly distributed between the two extreme values. In the other limit T2 relaxation is assumed to be fast relative to the time of flight through the magnet. In this case the z coordinate takes one of two possible values as observed in the original Stern‐Gerlach experiment. Due to the presence of a relaxation process involving transfer of angular momentum between particle and magnet the initially entangled spin state changes character leading to a loss of correlation between the two spins. In the original derivations of Bell's theorem based on a coincidence Stern‐Gerlach setup one assumes both a perfect correlation between the spins and only two possible values for the z‐coordinate on exit. According to the present calculations one can satisfy either of these conditions but not both simultaneously.
3

Microstructural Explicit Simulation of Grain Boundary Diffusion in Depleted Uranium Oxide

January 2011 (has links)
abstract: ABSTRACT The behavior of the fission products, as they are released from fission events during nuclear reaction, plays an important role in nuclear fuel performance. Fission product release can occur through grain boundary (GB) at low burnups; therefore, this study simulates the mass transport of fission gases in a 2-D GB network to look into the effects of GB characteristics on this phenomenon, with emphasis on conditions that can lead to percolation. A finite element model was created based on the microstructure of a depleted UO2 sample characterized by Electron Backscattering Diffraction (EBSD). The GBs were categorized into high (D2), low (D1) and bulk diffusivity (Dbulk) based on their misorientation angles and Coincident Site Lattice (CSL) types. The simulation was run using different diffusivity ratios (D2/Dbulk) ranging from 1 to 10^8. The model was set up in three ways: constant temperature case, temperature gradient effects and window methods that mimic the environments in a Light Water Reactor (LWR). In general, the formation of percolation paths was observed at a ratio higher than 10^4 in the measured GB network, which had a 68% fraction of high diffusivity GBs. The presence of temperature gradient created an uneven concentration distribution and decreased the overall mass flux. Finally, radial temperature and fission gas concentration profiles were obtained for a fuel pellet in operation using an approximate 1-D model. The 100 µm long microstructurally explicit model was used to simulate, to the scale of a real UO2 pellet, the mass transport at different radial positions, with boundary conditions obtained from the profiles. Stronger percolation effects were observed at the intermediate and periphery position of the pellet. The results also showed that highest mass flux happens at the edge of a pellet at steady state to accommodate for the sharp concentration drop. / Dissertation/Thesis / M.S. Materials Science and Engineering 2011
4

Um índice coincidente para a atividade econômica do comércio varejista no Rio Grande do Sul

Torres, Gabriel Picavêa January 2014 (has links)
O objetivo deste trabalho é a construção de um indicador coincidente (IC) para a atividade econômica do segmento de Comércio Varejista dentro da economia do estado do Rio Grande do Sul. A utilização de variáveis que apresentem comportamento comum entre si e altamente correlacionado com as Vendas do Varejo é o ponto de partida para a investigação a seguir. A metodologia adotada é a dos modelos de Fator Dinâmico de Stock e Watson (1988, 1989, 1991, 1993). Os resultados encontrados apontam um indicador final satisfatório, em termos de MAPE (erro absoluto percentual médio, em inglês) com relação às séries de Vendas do Varejo, especificamente a série da FEE/Fecomércio-RS – que tratava-se de uma pesquisa censitária. Em termos de fundamentos econômicos o IC é composto por variáveis que sabidamente afetam o consumo de bens: renda, crédito e confiança do consumidor. Um destaque está para o alto peso das variáveis de Crédito e Sentimento sobre a Situação Presente, o que sugere que o fluxo de renda futuro e a confiança para assumir endividamentos longos são determinantes para o segmento. Considerando um horizonte maior para a ampliação dessa pesquisa, postula-se que a construção de novos dados regionalizados para crédito, renda pela PNAD Contínua, séries mais longas para índices de confiança, e indicadores sobre estoques no Comércio podem melhorar os resultados encontrados. / The following research intends to build a coincident indicator to the Retail sector’s economic activity within the regional economy of Rio Grande do Sul. The starting point to reach this objective is to use variables which present common cyclical behavior with each other, as well as with Retail Trade indices. The investigation will be carried on using Stock and Watson’s (1988, 1989, 1991, 1993) Dynamic Factor models methodology. The research returned a result a final index which can be classified as satisfactory, when evaluated by the mean absolute percentage error with Retail Trade indices, specially the FEE/Fecomércio-RS’ index – which was a censitary research. The built Coincident Indicator is composed by variables correlated with consumption, according to the economic theory: income, credit and consumer’s confidence. Variables such as Consumer Credit and Consumer’s Sentiment towards Present Economic Situation presented high weight in the indicator, which suggests that future income flows and confidence to take long term debt are crucial for the sector’s economic activity. Considering an expanded horizon for this research, one believes that new regional data for Household Credit, income through PNAD Contínua, a longer sample for Consumer’s Confidence indices, and indicators measuring stock levels in Retail might improve the coincident indicator.
5

Um índice coincidente para a atividade econômica do comércio varejista no Rio Grande do Sul

Torres, Gabriel Picavêa January 2014 (has links)
O objetivo deste trabalho é a construção de um indicador coincidente (IC) para a atividade econômica do segmento de Comércio Varejista dentro da economia do estado do Rio Grande do Sul. A utilização de variáveis que apresentem comportamento comum entre si e altamente correlacionado com as Vendas do Varejo é o ponto de partida para a investigação a seguir. A metodologia adotada é a dos modelos de Fator Dinâmico de Stock e Watson (1988, 1989, 1991, 1993). Os resultados encontrados apontam um indicador final satisfatório, em termos de MAPE (erro absoluto percentual médio, em inglês) com relação às séries de Vendas do Varejo, especificamente a série da FEE/Fecomércio-RS – que tratava-se de uma pesquisa censitária. Em termos de fundamentos econômicos o IC é composto por variáveis que sabidamente afetam o consumo de bens: renda, crédito e confiança do consumidor. Um destaque está para o alto peso das variáveis de Crédito e Sentimento sobre a Situação Presente, o que sugere que o fluxo de renda futuro e a confiança para assumir endividamentos longos são determinantes para o segmento. Considerando um horizonte maior para a ampliação dessa pesquisa, postula-se que a construção de novos dados regionalizados para crédito, renda pela PNAD Contínua, séries mais longas para índices de confiança, e indicadores sobre estoques no Comércio podem melhorar os resultados encontrados. / The following research intends to build a coincident indicator to the Retail sector’s economic activity within the regional economy of Rio Grande do Sul. The starting point to reach this objective is to use variables which present common cyclical behavior with each other, as well as with Retail Trade indices. The investigation will be carried on using Stock and Watson’s (1988, 1989, 1991, 1993) Dynamic Factor models methodology. The research returned a result a final index which can be classified as satisfactory, when evaluated by the mean absolute percentage error with Retail Trade indices, specially the FEE/Fecomércio-RS’ index – which was a censitary research. The built Coincident Indicator is composed by variables correlated with consumption, according to the economic theory: income, credit and consumer’s confidence. Variables such as Consumer Credit and Consumer’s Sentiment towards Present Economic Situation presented high weight in the indicator, which suggests that future income flows and confidence to take long term debt are crucial for the sector’s economic activity. Considering an expanded horizon for this research, one believes that new regional data for Household Credit, income through PNAD Contínua, a longer sample for Consumer’s Confidence indices, and indicators measuring stock levels in Retail might improve the coincident indicator.
6

Um índice coincidente para a atividade econômica do comércio varejista no Rio Grande do Sul

Torres, Gabriel Picavêa January 2014 (has links)
O objetivo deste trabalho é a construção de um indicador coincidente (IC) para a atividade econômica do segmento de Comércio Varejista dentro da economia do estado do Rio Grande do Sul. A utilização de variáveis que apresentem comportamento comum entre si e altamente correlacionado com as Vendas do Varejo é o ponto de partida para a investigação a seguir. A metodologia adotada é a dos modelos de Fator Dinâmico de Stock e Watson (1988, 1989, 1991, 1993). Os resultados encontrados apontam um indicador final satisfatório, em termos de MAPE (erro absoluto percentual médio, em inglês) com relação às séries de Vendas do Varejo, especificamente a série da FEE/Fecomércio-RS – que tratava-se de uma pesquisa censitária. Em termos de fundamentos econômicos o IC é composto por variáveis que sabidamente afetam o consumo de bens: renda, crédito e confiança do consumidor. Um destaque está para o alto peso das variáveis de Crédito e Sentimento sobre a Situação Presente, o que sugere que o fluxo de renda futuro e a confiança para assumir endividamentos longos são determinantes para o segmento. Considerando um horizonte maior para a ampliação dessa pesquisa, postula-se que a construção de novos dados regionalizados para crédito, renda pela PNAD Contínua, séries mais longas para índices de confiança, e indicadores sobre estoques no Comércio podem melhorar os resultados encontrados. / The following research intends to build a coincident indicator to the Retail sector’s economic activity within the regional economy of Rio Grande do Sul. The starting point to reach this objective is to use variables which present common cyclical behavior with each other, as well as with Retail Trade indices. The investigation will be carried on using Stock and Watson’s (1988, 1989, 1991, 1993) Dynamic Factor models methodology. The research returned a result a final index which can be classified as satisfactory, when evaluated by the mean absolute percentage error with Retail Trade indices, specially the FEE/Fecomércio-RS’ index – which was a censitary research. The built Coincident Indicator is composed by variables correlated with consumption, according to the economic theory: income, credit and consumer’s confidence. Variables such as Consumer Credit and Consumer’s Sentiment towards Present Economic Situation presented high weight in the indicator, which suggests that future income flows and confidence to take long term debt are crucial for the sector’s economic activity. Considering an expanded horizon for this research, one believes that new regional data for Household Credit, income through PNAD Contínua, a longer sample for Consumer’s Confidence indices, and indicators measuring stock levels in Retail might improve the coincident indicator.
7

Interfacial structure of delta phase in Inconel 718 and the selection of precipitate habit planes

Liang, Qiang 11 May 2006 (has links)
We investigated the structure and defects associated with interphase boundaries between a γ (fcc) matrix and plate-shaped precipitates of the δ (orthorhombic) phase in Inconel 718. Based upon transmission electron microscopy (TEM) observations, the average habit plane was confirmed to be (111)<sub>γ</sub> which is consistent with previous reports. A parallel array of misfit dislocations with Burgers vector b=1/6[112̅]<sub>γ</sub>, (designated M1) are always observed lying along the [11̅0] direction. Another array of misfit dislocations appears in some regions of the interface with Burgers vector b=1/6[21̅1̅]<sub>γ</sub> (designated M2). These dislocations also lie along the [11̅0] direction. Irregular ledges were identified on the interface and are believed to contribute to the thickening of δ plates. Dislocations in the matrix were also characterized. Most matrix dislocations have a 1/2[1̅01]<sub>γ</sub> Burgers vector. The growth ledges in the habit plane of a single δ plate have a variety of effective Burgers vectors. A geometric matching approach based upon near-coincident sites was employed to explain the interfaces structure of interphase boundaries in Inconel 718, as well as fdc/bcc in Ni-45wt% Cr. In both cases, the conjugate plane is the plane with the highest areal density of near-coincident sites over a small region while the average habit plane is determined by the continuity of near-coincidence sites over a large area. The M1 interfacial dislocations in the γ/δ interface accommodate misfit in the habit plane whereas M2 dislocations do not and are probably a by-product of the dissociation of matrix dislocations. In the fcc/bcc system, the habit plane is not parallel to the conjugate plane and the partial dislocations associated with matrix stacking faults improve matching in the habit plane even though their Burgers vector lies out of this plane. / Ph. D.
8

Estrutura de prática e idade no processo adaptativo da aprendizagem de uma tarefa de timing coincidente / Practice schedule and age on the adaptive process of the coincident timing task learning

Gonçalves, Lucia Afonso 17 April 2009 (has links)
O objetivo desse estudo foi investigar os efeitos de diferentes estruturas de prática no processo adaptativo da aprendizagem de uma tarefa de timing coincidente em função da idade. Crianças (n=40), adultos (n=47) e idosos (n=57) foram distribuídos em grupos de prática constante, aleatória, constante-aleatória e aleatória-constante. A tarefa consistiu em tocar certos alvos de forma seqüencial em integração a um estímulo visual. O delineamento envolveu duas fases de aprendizagem: estabilização e adaptação. Os dados foram analisados em relação aos erros absoluto, variável, constante e de execução. Os resultados mostraram que o processo adaptativo na aprendizagem de crianças, adultos e idosos de uma tarefa de timing coincidente foi beneficiado pela prática constante-aleatória / The objective of this study was to investigate the effects of different practice schedule on the adaptive process of the coincident timing task learning in function of age. Children (n=40), adults (n=47) and elderly (n=57) were distributed in constant, random, constant-random and random-constant practices group. The task consisted of touching response keys sequentially in conjunction with a visual stimulus. The experimental design involved two learning phases: stabilization and adaptation. The data were analyzed in terms of absolute, variable, constant and execution errors. The results showed that adaptive process in the learning of children, adults and elderly of a coincident timing task was beneficed by constant-random practice
9

Estrutura de prática e idade no processo adaptativo da aprendizagem de uma tarefa de timing coincidente / Practice schedule and age on the adaptive process of the coincident timing task learning

Lucia Afonso Gonçalves 17 April 2009 (has links)
O objetivo desse estudo foi investigar os efeitos de diferentes estruturas de prática no processo adaptativo da aprendizagem de uma tarefa de timing coincidente em função da idade. Crianças (n=40), adultos (n=47) e idosos (n=57) foram distribuídos em grupos de prática constante, aleatória, constante-aleatória e aleatória-constante. A tarefa consistiu em tocar certos alvos de forma seqüencial em integração a um estímulo visual. O delineamento envolveu duas fases de aprendizagem: estabilização e adaptação. Os dados foram analisados em relação aos erros absoluto, variável, constante e de execução. Os resultados mostraram que o processo adaptativo na aprendizagem de crianças, adultos e idosos de uma tarefa de timing coincidente foi beneficiado pela prática constante-aleatória / The objective of this study was to investigate the effects of different practice schedule on the adaptive process of the coincident timing task learning in function of age. Children (n=40), adults (n=47) and elderly (n=57) were distributed in constant, random, constant-random and random-constant practices group. The task consisted of touching response keys sequentially in conjunction with a visual stimulus. The experimental design involved two learning phases: stabilization and adaptation. The data were analyzed in terms of absolute, variable, constant and execution errors. The results showed that adaptive process in the learning of children, adults and elderly of a coincident timing task was beneficed by constant-random practice
10

The effect of a perceptual-motor training programme on the coincident anticipation timing and batting performance of club cricket players

Van Velden, Grant David 12 1900 (has links)
Thesis (M Sport Sc (Sport Science)-- University of Stellenbosch, 2010. / ENGLISH ABSTRACT: The purpose of this study was to determine the effects of a perceptual-motor training programme on the coincident anticipation timing and batting performance of university club cricket players. The intervention programme focused on developing players‟ visual attention and concentration. Vickers‟ (2007) Three-Step Decision Training Model was used to structure the training sessions. The study followed a repeated measures experimental design with three groups (experimental, placebo, and control) formed by volunteers from a university club cricket team. The independent variable was a four-week training programme. The dependent variables were coincident anticipation timing and performance on a cricket batting test. Subjects were pre- and post-tested with retention tests occurring after a set period of “no training” following the post-tests. Differences between groups were compared using Kruskal-Wallis ANOVA by Ranks Tests. Differences within each group were compared using multiple Mann-Whitney U-Tests. No significant improvements were observed in the experimental group‟s coincident anticipation timing and batting performance. Although neither coincident anticipation timing nor batting performance significantly improved, further research into the use of Vickers‟ (2007) Model to enhance sport performance is recommended. / AFRIKAANSE OPSOMMING: Die doel van hierdie studie was om die uitwerking van ʼn perseptueel-motoriese opleidingsprogram op die samevallende vooruittydsberekening (“coincident anticipation timing”) en kolfprestasie van universiteitsklubkrieketspelers te bepaal. Die klem van die intervensieprogram het op die ontwikkeling van spelers se visuele aandag en konsentrasie geval. Die opleidingsessies is volgens Vickers (2007) se drieledige model vir besluitnemingsopleiding saamgestel. Die studie het ʼn eksperimentele ontwerp van herhaalde metings op drie groepe (eksperimenteel, plasebo en kontrole) van ʼn universiteitsklubkrieketspan toegepas. Die onafhanklike veranderlike was ʼn vier weke lange opleidingsprogram. Die afhanklike veranderlikes was samevallende vooruittydsberekening, en prestasie in ʼn krieketkolftoets. Proefpersone het voor en net ná die opleiding toetse ondergaan, sowel as behoudtoetse drie weke ná die na-opleidingstoetse. Verskille tussen groepe is met behulp van rangtoetse uit Kruskal-Wallis se variansie-analisemodel (ANOVA) bepaal, terwyl verskille binne groepe met veelvuldige Mann-Whitney-U-toetse vergelyk is. Geen beduidende verbetering is in die eksperimentele groep se samevallende vooruittydsberekening of kolfprestasie waargeneem nie. Hoewel nóg samevallende vooruittydsberekening nóg kolfprestasie aansienlik verbeter het, word verdere navorsing oor die gebruik van Vickers (2007) se model vir die verbetering van sportprestasie aanbeveel.

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