1,720,999 research outputs found
Assessing the geometry and tuning properties of historical timbilas through non-destructive reverse engineering techniques
Full text linkTimbilas are xylophones finely manufactured and tuned by the Chopi people from Mozambique. In the context of a research project, we aim at assessing the construction and acoustical features of a set of historical instruments by developing non-destructive characterization techniques based on reverse engineering, with main objectives to assess their original tuning and musical scale. In this thesis, we present the methodology and workflow that have been developed for the study of the collection of historical timbilas of the National Museum of Ethnology of Lisbon, which is the world's largest collection of the Mozambican instrument. In a first stage, contactless geometrical measurements were performed on a ninebar timbila by using 3D scanning Technology, resulting in a detailed geometrical description of the instrument bars. In a second stage, the 3D collected geometrical data was used as input to Finite Element computations in order to calculate the modal frequencies and mode shapes of each bar of the instrument. Results stemming from our modal computations were compared with modal data obtained from vibrational measurements, proving the efficiency of the proposed approach. Final stage was using the data as input for developing a sound synthesis model for recreating the sound of the timbila bars.Timbilas são xilofones cuidadosamente construídos e afinados pelos Chopes, povo de Moçambique que cultiva uma das mais importantes tradições musicais do sul da África. No contexto de um projeto interdisciplinar de investigação, objetivamos avaliar as características geométricas e acústicas de alguns exemplares históricos, desenvolvendo técnicas não-destrutivas de caracterização baseadas num processo de engenharia reversa, com o principal objetivo de avaliar a afinação e a escala musical de um conjunto de instrumentos. A metodologia desenvolvida consiste no levantamento preciso da geometria das barras a partir de tecnologia de imagens scanner 3D, resultando numa descrição detalhada de sua morfologia. Num segundo passo, realizamos cálculos modais a partir de um modelo por Elementos Finitos 3D construido a partir dos dados coletados, a fim de calcular as frequências modais e formas vibratórias das principais ressonâncias de cada barra do instrumento. Os resultados dos cálculos modais foram finalmente comparados com os valores de parâmetros modais identificados a partir de medições vibratórias, demonstrando a utilidade e eficácia da metodologia proposta. O estágio final foi a utilização dos dados para criar um modelo de síntese sonora para as barras da timbila
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
A Herança de Django- Perspetivas etnomusicologicas e acústicas da guitarra Manouche
Full text linkInspirado na obra do guitarrista de origem Manouche, Django Reinhardt, o Gypsy
jazz ou jazz Manouche está presente em festivais internacionais de jazz e de músicas do
mundo. Esse género desenvolveu-se no seio de uma comunidade e encontrou a sua
própria voz numa guitarra icónica. Para compreender o som da guitarra associada aos
Manouches é necessário estar atento à sua anatomia e resposta mecânica, mas também à
forma e contexto de sua utilização.
Nesse trabalho as características vibratórias da guitarra Manouche foram
estudadas em ensaios laboratoriais e sua morfologia detalhada levando em consideração
discussões com luthiers especializados na construção de tal instrumento. Durante dois
anos foi desenvolvido um trabalho de campo que permitiu compreender como, por quem
e em quais conjunturas esse instrumento é utilizado. Finalmente investigou-se a
influência da prática comunitária e da pedagogia do jazz Manouche no som que ouvimos
quando um músico toca uma guitarra Manouche.
Esta tese elucida como características de um instrumento, conceções estéticas de
músicos do género Manouche e técnicas performativas interligam-se para definir o som
da guitarra Manouche.Inspired by the work of Manouche guitarist Django Reinhardt, Gypsy jazz or jazz
Manouche is present at international jazz and world music festivals. This musical genre
developed within a community and found its voice in an iconic guitar. To understand the
guitar’s sound associated with Manouche people, we need to be aware of the nature of a
specific instrument and the way and context of its utilization.
In this research, we studied the vibratory characteristics of the Manouche guitar
in the laboratory and detailed its morphology, referencing discussions with luthiers
specialized in this instrument’s construction. Two years of fieldwork allowed us to view
this instrument inserted into context, observing how it is used, by whom, and the
importance of community practice and the pedagogy of jazz Manouche in the sound we
hear when a musician plays a Manouche guitar.
Therefore, this thesis elucidates how the characteristics of an instrument, sound
conceptions of musicians of the Manouche genre, and performance techniques
interconnect to define the sound of the Manouche guitar
Evolução do comportamento dinâmico de uma guitarra submetida a tratamento vibratório localizado
No full textDissertação de Mestrado Integrado em Engenharia Mecânica apresentada à Faculdade de Ciências e TecnologiaÉ amplamente reconhecido que músicos que tocam instrumentos de corda, tomando o exemplo do violino e da guitarra, acreditam que a qualidade de som dos seus instrumentos melhora com a sua idade e/ou uso constante. Isto justificou o surgimento de aparelhos comerciais que prometem melhorar a qualidade dos instrumentos através de vibrações contínuas forçadas. Na procura de evidência científica sobre o efeito das vibrações, induzidas quando o instrumento é tocado, na qualidade do seu timbre, desenvolvemos um set-up mecânico com o intuito de reproduzir as vibrações mecânicas que a que as guitarras estão sujeitadas quando são tocadas e depois aplicar um tratamento vibratório numa guitarra de teste. Resolvendo um problema inverso, identificamos com sucesso o sinal a ser aplicado na guitarra de forma a reproduzir fielmente os sinais de aceleração medidos no corpo da guitarra quando esta foi tocada por um guitarrista profissional. A guitarra é então submetida a um tratamento continuo diário com a aplicação destas mesmas vibrações, num ambiente de temperatura e humidade controlados. Em diferentes fases do tratamento, efetuamos uma análise modal experimental da guitarra na gama das baixas frequências, permitindo acompanhar a evolução das propriedades vibratórias do instrumento com o tempo de excitação. A intenção será de provar ou negar o efeito que estas vibrações possuem no comportamento dinâmico do instrumento e que o tratamento vibratório desenvolvido possa ser utilizado em futuros estudos para avaliar melhor os efeitos do tempo total de vibração, as variações de temperatura e humidade relativa, entre outros.It is well accepted that musicians who play string instruments, taking the example of violins and guitars, believe that the sound quality of their instruments improves with age and/or regular practice. This motivated the appearance of commercially available products that promise to improve instrument sound through the exposure to continuous forced vibrations. In search of scientific evidence on the effect of playing-induced vibrations on tone quality, we develop a mechanical set-up intended to reproduce the mechanical vibrations undergone by guitars when played by musicians, and then apply a specific vibration treatment on a test guitar. Solving an inverse problem, we successfully identify the drive signal to be applied on the guitar in order to accurately reproduce acceleration signals measured on the guitar body when played by a professional guitarist. Using the developed set-up, the test guitar is then submitted to a continuous daily treatment under controlled conditions of temperature and humidity. Experimental modal analysis of the guitar is then regularly performed at different stages of the treatment, thus allowing to study the evolution of the vibrational properties of the instrument during the treatment. The intention is then to prove or disprove the effect that these vibrations could influence the dynamical behaviour of the instrument, and to allow in the future, the development of further studies to evaluate the effects of the total vibration time, the changes in temperature and relative humidity, among others
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