• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 238
  • 46
  • 26
  • 19
  • 9
  • 4
  • 3
  • 2
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 421
  • 184
  • 57
  • 41
  • 39
  • 35
  • 31
  • 30
  • 28
  • 26
  • 23
  • 21
  • 20
  • 19
  • 18
  • 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.
381

A Study of Couping Element Based Antenna Structure

Zhao , Hai, Lin, Gui January 2009 (has links)
This thesis presents a study on built-in type low profile and low volume mobile phone antennas. In a coupling element based antenna, the chassis is the main radiator and the antenna elements are the exciters for the wave modes at low frequency. The main work of this thesis is to demonstrate and investigate the performance of the coupling element based antenna and study a variety of cases with different physical lengths and different physical heights. The investigation is done by using simulators. The performance is evaluated by analyzing the impedance bandwidth and the efficiency. For the study, antenna prototypes integrating miniaturized matching circuits were modeled. Two antenna structure prototypes covering five frequency bands were manufactured and measured. The Measured results are presented and compared with simulations. Finally, the performance of the coupling element based antenna is compared with planar inverter-F antenna (PIFA) and discussed.
382

Change point estimation in noisy Hammerstein integral equations / Sprungstellen-Schätzer für verrauschte Hammerstein Integral Gleichungen

Frick, Sophie 02 December 2010 (has links)
No description available.
383

The search for diffuse interstellar bands in quasar absorption line systems

York, Brian A. 15 August 2008 (has links)
The diffuse interstellar bands (DIBs) probably arise from complex organic molecules whose strength in local galaxies correlates with neutral hydrogen column density, N(H I), and dust reddening, E(B−V). Because Damped Lyman-α systems are known to have high N(H I), and Ca II absorbers in quasar (QSO) spectra are posited to have high N(H I) and reddening, both represent promising sites for the detection of DIBs at cosmological distances. I present the results of a search for diffuse bands in seven DLAs and nine Ca II absorbers. I announce the detection of the first narrow DIBs at z>0 towards one DLA and one Ca II system. I further investigate the relative strengths of the DIBs as well as their correlations with N(H I) and E(B−V). Finally, I discuss the prospects for using DIBs to better understand the properties of quasar absorption systems, and for using DIB searches in absorption systems to better understand the properties of DIBs.
384

The search for diffuse interstellar bands in quasar absorption line systems

York, Brian A. 15 August 2008 (has links)
The diffuse interstellar bands (DIBs) probably arise from complex organic molecules whose strength in local galaxies correlates with neutral hydrogen column density, N(H I), and dust reddening, E(B−V). Because Damped Lyman-α systems are known to have high N(H I), and Ca II absorbers in quasar (QSO) spectra are posited to have high N(H I) and reddening, both represent promising sites for the detection of DIBs at cosmological distances. I present the results of a search for diffuse bands in seven DLAs and nine Ca II absorbers. I announce the detection of the first narrow DIBs at z>0 towards one DLA and one Ca II system. I further investigate the relative strengths of the DIBs as well as their correlations with N(H I) and E(B−V). Finally, I discuss the prospects for using DIBs to better understand the properties of quasar absorption systems, and for using DIB searches in absorption systems to better understand the properties of DIBs.
385

Regiões de incerteza para a curva ROC em testes diagnósticos

Vaz, Janaina Cândida Lopes 03 March 2009 (has links)
Made available in DSpace on 2016-06-02T20:06:03Z (GMT). No. of bitstreams: 1 2711.pdf: 1912872 bytes, checksum: 297e56759e248cb7127eae6094c0d821 (MD5) Previous issue date: 2009-03-03 / Financiadora de Estudos e Projetos / Diagnostic tests are methods capable of indicating the presence or absence of a disease, with a probability of error. The performance of a diagnostic test can be verified by some indicator, as: the specificity, the sensitivity and the ROC curve. A graph of the specificity complement versus sensitivity is called as ROC curve. The ROC curve demonstrates the test s ability to discriminate the different disease diagnosis, therefore it is a graphical tool that is used to assess the performance of a test. We define three types of confidence regions around the ROC curve: the punctual, the regional and the global. In some instances, depending on the clinical needs, the decision is taken under an specific region of the ROC curve. We review some procedures for estimating confidence region for the ROC curve and we propose two new methods (optimized averages and averages thresholds optimized) to estimating that region. We use the bootstrap method to search for a confidence region around the ROC curve. Using numerical examples, we apply the methods an compare their performance. / Testes diagnósticos são métodos capazes de indicar a presença ou ausência de uma doença, com uma probabilidade de erro. O desempenho de um teste diagnóstico pode ser verificado por algum indicador, como: a especificidade, a sensibilidade e a curva ROC. Um gráfico do complemento da especificidade versus sensibilidade é chamado de curva ROC. A curva ROC demonstra a habilidade do teste em discriminar os diferentes diagnósticos da doença, logo é uma ferramenta gráfica que serve para avaliar o desempenho de um teste. Definimos três tipos de regiões de confiança em torno da curva ROC: as pontuais, as regionais e as globais. Em algumas situações, de acordo com a necessidade do clínico, uma decisão é tomada sobre uma determinada região específica da curva ROC. Revisamos alguns procedimentos para estimar a região de confiança para a curva ROC e propomos dois novos métodos (médias otimizadas e médias limiares otimizadas) para estimar essa região. Usamos o método bootstrap para buscar uma região de confiança em torno da curva ROC. Usando exemplos numéricos, aplicamos os métodos para comparar seus desempenhos.
386

Bandas musicais do meio oeste catarinense: características e processos de musicalização

Kandler, Maira Ana 24 May 2011 (has links)
Made available in DSpace on 2016-12-08T17:06:53Z (GMT). No. of bitstreams: 1 maira.pdf: 1402315 bytes, checksum: eb2f3c1265322b4f23da3bb5929c9bd4 (MD5) Previous issue date: 2011-05-24 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This research focuses on the musicalization processes performed at the wind bands of mid-west Santa Catarina. In order to help elucidating such processes, it was necessary to set a context for the object of study, bringing data referring to the history of these groups, repertoire, performances, new members admission criteria and institutional bond. The research presents data concerning the conductors and other related professionals involved in the process of musicalization and also the profile of the wind band members. The theoretical reference that guided this study is based on the concept of musicalization developed by Penna (1990) and on Pierre Bourdieu‟s concept of habitus (1994, 2001, 2005, 2007). The survey method associated with the qualitative approach describes the methodology used in this study. The data collection was carried out through semi-structured interviews with the main conductors of the alluded bands. The data analysis demonstrated that these wind bands share certain characteristics with each other and with other Brazilian bands. Similarities among the bands were found in relation to the events where the groups perform, the criteria used to select and accept students to musical education, the musical education and background of the conductors and the criteria adopted by the conductors regarding the repertoire selection. The processes of musicalization developed at the participant groups of this study also present similarities, pointing towards music initiation through theoretical study, showing emphasis on the comprehension of musical codes and on the performance of musical instruments. The final considerations present reflections concerning the methods of research, the collected data; stress the importance of the musical education of the conductors when conducting and teaching music to the wind bands and also presenting suggestions for future studies / Esta pesquisa investiga os processos de musicalização realizados nas bandas de música do meio oeste catarinense. Para auxiliar na compreensão dos processos de musicalização desenvolvidos, considerou-se necessário contextualizar o objeto de estudo, trazendo informações referentes à história desses grupos, repertório, apresentações, critérios de admissão de novos integrantes e vínculo institucional. A pesquisa apresenta dados referentes aos maestros e outros profissionais que estão envolvidos no processo de musicalização e também características dos integrantes das bandas. O referencial teórico que norteou o trabalho está baseado no conceito de musicalização desenvolvido por Penna (1990) e no conceito de habitus de Pierre Bourdieu (1994, 2001, 2005, 2007). A metodologia utilizada foi o survey aliado à abordagem qualitativa. A coleta de dados foi realizada através de entrevistas semiestruturadas com os maestros titulares das bandas investigadas. A análise dos dados demonstra que as bandas investigadas apresentam características semelhantes entre si e também com outras bandas existentes no Brasil. Semelhanças entre as bandas foram encontradas em relação aos eventos onde os grupos se apresentam, aos critérios estipulados para o ingresso de alunos no aprendizado musical, à formação musical dos maestros e aos critérios adotados pelos regentes para a escolha do repertório. Os processos de musicalização desenvolvidos nos grupos participantes deste estudo também apresentam similaridades, apontando para a iniciação musical através do estudo teórico, a ênfase na compreensão dos códigos musicais e na execução do instrumento. As considerações finais trazem reflexões acerca do processo de pesquisa, dos dados recolhidos, destacam a importância da formação musical dos maestros para atuarem na regência e no ensino de música nas bandas e também apresentam sugestões para pesquisas futuras
387

Influência do treinamento motor com biofeedback eletromiográfico na reabilitação da espasticidade após ave e a caracterização da atividade cortical correlata

Vieira, Débora 11 February 2016 (has links)
Conselho Nacional de Desenvolvimento Científico e Tecnológico / A espasticidade é observada na maioria dos pacientes após Acidente Vascular Encefálico (AVE), e exercem influência na presença de deficiências e incapacidades, comprometendo a função motora. As estratégias de neuroreabilitação, o biofeedback eletromiográfico (EMG), têm sido utilizado com aceitação na comunidade médica para reajustes nas habilidades sensório-motoras como retreinamento motor, redução da espasticidade e/ou treinamento de relaxamento. A intervenção ainda apresenta evidências delimitadas quanto a sua efetividade na reabilitação, principalmente, quanto a interferência sobre a atividade cortical e na redução dos sinais espásticos que oferece características negativas na execução do movimento. O objetivo dessa pesquisa foi analisar a possível interferência do treino com biofeedback eletromiográfico sobre a conscientização do controle motor no membro espástico e a caracterização da atividade das bandas de baixa frequência em diferentes regiões corticais orientada pela técnica de treinamento. Dezesseis voluntários acometidos por AVE isquêmicos foram selecionados e divididos em dois grupos (n=8). Grupo experimental (GE) submetidos ao treino com biofeedback associado a fisioterapia, e o grupo controle (GC) submetido apenas à fisioterapia convencional. Foi realizada a avaliação do grau de espasticidade pelo limiar de reflexo do estiramento tônico (LRET) e pela Escala Modificada de Ashworth (EMA) antes e três semanas após o término do treinamento com a técnica. Os sujeitos foram submetidos ao biofeedback durante 6 semanas, com 2 sessões semanalmente. O mesmo tempo para o tratamento fisioterápico foi padronizado para o GC. Os resultados mostram variação do percentual médio de melhora do grau de espasticidade, mensuradas pelo LRET, de 38,59% (dp=13,03%) no GE comparado com 18,58% (dp=11,90%) do GC. Essa variação apresentou diferença significativa (p=0,020; t=2,776; p<5%) entre os grupos (controle e experimental), e a diferença significativa do LRET antes e após do treinamento no GE (p=0,003; t=5,338; p<5%) quando comparado ao GC (p=0,015; t=3,657; p<5%). A medida semi-quantitativa da EMA antes e após o término das sessões mostraram variações apenas no GE. Com relação a atividade cortical, houve diferença de atividade das bandas (delta, teta, alfa e beta) quando a 3ª e 12ª sessão foram comparadas para cada sujeito do GE. Essa diferença foi encontrada, principalmente, em regiões frontal, central (vértex), parietal e occipital em ambos hemisférios (ipsilateral e contralateral a lesão) tanto na fase de planejamento cognitivo motor quanto na execução do movimento. Houve predominância da diferença de atividade para a banda delta, alfa e beta em diferentes sujeitos distribuída difusamente ao longo dos canais de registro de viii EEG. A atividade diferenciada das bandas foi devido ao aumento e/ou diminuição da energia espectral entre as sessões, notado apenas em alguns voluntários do GE. Observou ainda diferença de atividade em áreas motoras secundárias. As avaliações, principalmente do LRET mostram que o treino com biofeedback EMG foi efetivo na redução do grau de espasticidade. A diferença de atividade cortical das bandas de frequência entre as sessões sugere que o biofeedback modula a cognição por meio do esforço e atenção imposta pela tarefa na tentativa do movimento no membro acometido. Além de que a diferença de energia espectral entre as sessões é dependente do ajuste e complexidade da tarefa direcionado pelos sinais do biofeedback, auxiliando na aprendizagem motora. / Spasticity is observed in most patients after cerebrovascular accident (CVA), and exerts influence in the presence of disabilities, affecting motor function. For neurorehabilitation strategies, electromyographic biofeedback (EMG) has been used with acceptance in the medical community for adjustments in the sensory-motor skills as a motor retraining, reducing spasticity and/or relaxation training. The intervention still presents limited evidence regarding their effectiveness in rehabilitation, especially as the interference of cortical activity and the reduction of spastic signs that provides negative characteristics in movement execution. The aim of this study was to analyze the workout possible interference with EMG biofeedback on the motor control awareness in spastic member in the characterization of the activity of low-frequency bands in different cortical regions targeted by the training technique. Sixteen volunteers affected by ischemic stroke were selected and divided into two groups (n = 8). Experimental group (EG) underwent biofeedback training associated with physical therapy and control group (CG) only conventional physiotherapy. The assessment of the degree of spasticity by reflex threshold of the tonic stretch (TSRT) and Modified Ashworth Scale (MAS) was performed before and three weeks after the end of treatment with the technique. The subjects underwent biofeedback for 6 weeks, with two sessions weekly. The same time for physiotherapy treatment was standardized to the GC. The results show variation of the average percent improvement in the degree of spasticity measured at TRST, 38,59% (sd=13,03%) in GE compared to 18,58% (sd=11,90%) of GC. This variation showed a significant difference (p=0.020; t=2,776; p<5%) between groups (control and experimental), and the significant difference of TRST before and after training in EG (p = 0.003; t=5,338; p <5%) when compared to the CG (p=0.015; t=0,015; p<5%). The semi-quantitative measure of the MAS before and after the end of the sessions presented variations only in GE. Regarding the cortical activity, there were band activities differences when 3rd and 12th sessions were compared for each subject of GE. This difference was found primarily in the frontal, central (vertex), parietal and occipital lobe in both hemispheres (contralateral and ipsilateral to the lesion) in both the cognitive motor planning phase and in the movement execution. It was observed the predominance of activity difference for the delta band, alpha and beta in different subjects distributed diffusely over the EEG recording channels. The different activity of the bands was due to the increase and/or decrease the spectral energy between sessions, x noticed only in some GE volunteers. It was also pointed out distinct activity in secondary motor areas. Evaluations mainly from TSRT show that training with EMG biofeedback was effective in reducing the degree of spasticity. The difference in cortical activity of the frequency bands between sessions suggested that biofeedback modulates cognition through the effort and attention required by the task of movement attempt in the affected limb. Besides that, the spectral energy difference between the sessions depends on the tuning and task complexity driven by biofeedback signals, helping motor learning. / Tese (Doutorado)
388

Three essays in the economics of music: reputation and success of musicians

Ceulemans, Cédric 10 July 2013 (has links)
The music industry is a market of superstars, that is a market where a relatively small number of people earn enormous amounts of money and dominate the activity in which they engage (Rosen,1981). Theories on the superstars phenomenon suggest that luck (Adler, 1985) or talent (Rosen, 1981) are the driving forces behind success. Thus, the “superstars models” left performers with no “active” role: successful artists are either endowed with an innate talent far above the average or are extremely lucky. However, all musicians (talented or not; lucky or not) take continuously decisions that affect their career. Chapter 1 and 2 of this dissertation analyze in details some of these decisions and their influence on success.<p>Chapter 1, Rock Bands: Matching, Recording & Work Organization,4 investigates the impact of partnerships, matching, and work organization on the success of rock musicians using a unique database of 1,494 albums released between 1970 and 2004. We show that rock bands differ in their work organization because the agreements between the members of band are different. These agreements can be seen as implicit contracts. Drawing on this observation, we develop a model where agents (musicians) with different levels of creativity match (to form a band) and produce a joint output (a song). We show that the way agents match (positively or negatively) is correlated with success and depends on the (in)completeness of contracts. The theoretical results are supported by the data.<p>Chapter 2, Musical Characteristics and Success in Commercial Music, analyzes the relationship between musical characteristics, that can objectively be measured, and different types of success (commercial success, critical success, and success assessed by music lovers). We show that the strength and the direction (positive or negative) of the relationship between success and musical characteristics vary with the measure of success.<p>The third chapter goes in a slightly different direction than the two others as it deals with long term reputation of composers rather than commercial success of pop-rock musicians. Chapter 3, The Formation of the Canons of the Baroque Music, analyzes the reputation of baroque composers over time. The dataset makes it possible to describe the evolution of composers’ reputation and of the baroque canon. The entries in seven important musical dictionaries written between 1790 and 2000 are used to measure reputations. We provide evidence that a consensus exists between musicologists, who often rely on their predecessors’ work.<p><p>References:<p>Adler, M. (1985). Stardom and talent. American Economic Review, 75, 208-211.<p>Rosen, S. (1981). The economics of superstars, American Economic Review, 71, 845–858.<p> / Doctorat en Sciences économiques et de gestion / info:eu-repo/semantics/nonPublished
389

Vieillissements statique et dynamique et instabilités associées : expérimentation, modélisation et simulations numériques / Static and dynamic strain aging and associated instabilities : experimentation, modeling and numerical simulations

Nogueira de Codes, Rodrigo 07 September 2011 (has links)
L'objectif de cette thèse est d'étudier expérimentalement les phénomènes de vieillissement dus à la diffusion des atomes en solution dans les alliages d’aluminium et les instabilités qui leur sont associées comme le phénomène Portevin-Le Châtelier ou les bandes de Lüders et de proposer une modélisation de ces phénomènes dans le cadre de la thermodynamique des processus irréversibles. Une étude expérimentale détaillée est alors entreprise sur les alliages d’aluminium AA5083-H116 et AA5182-O. Le comportement du premier présente l’effet PLC de façon prononcée et les deux types d’instabilités sont observées simultanément pour le second. La corrélation d'images numériques et la thermographie infrarouge sont essentiellement employées pour détecter et caractériser les aspects spatiotemporels des instabilités observées. La déformation non homogène due à l’apparition et la propagation de bandes de localisation est mise en évidence. Ces bandes de déformation sont visualisées, permettant à leurs diverses caractéristiques (vitesse, orientation, largeur, vitesse de déformation à l'intérieur des bandes, augmentation de la température à l'intérieur des bandes) d'être mesurées sur des éprouvettes lisses (plates, cylindriques ou prismatiques). Dans le cas des éprouvettes plates, l’effet des épaisseurs de l’éprouvette a aussi été examiné. Les caractéristiques des bandes sont aussi analysées sur d’autres géométries d’éprouvette (entaillées avec divers types d’entailles) à des vitesses de déformation différentes pour exhiber leur morphologie en présence de chargements multiaxiaux. Des simulations non linéaires et tridimensionnelles ont été effectuées en utilisant le modèle de McCormick pour montrer comment la prise en compte des phénomènes de vieillissement, même partielle, permet de décrire les hétérogénéités et le mouvement des bandes de déformation ainsi que de prévoir leurs différentes caractéristiques. Enfin, en se basant sur les mécanismes physiques à la base des phénomènes de vieillissement et en soulignant les limites du modèle de McCormick, un modèle élasto-viscoplastique prenant en considération les phénomènes de vieillissement est proposé dans le cadre de la thermodynamique des processus irréversibles. / The objective of this thesis is to study experimentally the ageing phenomena due to the atoms diffusion in solid solutions in aluminium alloys and associated instabilities as the Portevin-Le Châtelier phenomenon or the Lüders bands and to propose a model of these phenomena within the framework of thermodynamics of irreversible processes. Digital Image Correlation (DIC) and Digital Infrared Thermography (DIT) are essentially employed to capture and characterize the spatio-temporal aspects of these instabilities. Inhomogeneous deformation, due to the appearance and the propagation of various localization bands are observed. These deformation bands are visualized, allowing their various characteristics (velocity, orientation, width, strain rate inside the bands, temperature increase inside the bands) to be measured on smooth specimens (flat, cylindrical or prismatic). In the case of flat test, the effect of the specimen thickness was also examined. The band characteristics are also analyzed on other specimen geometries (notched with various kinds of notches) at different strain rates to exhibit their morphology in the presence of multiaxial loadings. Some nonlinear and three-dimensional simulations were carried out with McCormick model to show how the inclusions of ageing phenomena, even partial, makes possible to describe heterogeneities and the deformation bands but also reproducing qualitatively their various characteristics. Finally, based on the physical mechanisms of aging phenomena and underlying the limitations of the McCormick model, an elasto-viscoplastic model taking into account the aging phenomena is proposed in the framework of thermodynamics of irreversible processes.
390

Rekonfigurovatelná vícepásmová anténa / Reconfigurable multiband antenna

Havlín, Radomil January 2011 (has links)
This thesis deals with modeling and produce of reconfigurable multi-band planar antennas, which allow electrical shifting of frequency band. After antennas simulation with PIN diode and FET switch in a commercial program CST MW, another step is to optimize the antenna for a new substrate. The next step was to produce antennas. Finally, the optimized antennas are compared with the measurement on experimental antennas.

Page generated in 0.0411 seconds