1,720,964 research outputs found
A method to estimate the rectangular orthotropic plate elastic constants using least-squares and Chladni patterns
Get PDFA method to retrieve the elastic constants of rectangular wooden plates is presented, relying on the measurement of a set of eigenfrequencies and the identification of the corresponding mode shapes, and belonging to the more general category of non-destructive inverse parameter estimation methods. Compared to previous work, the current method is effective with any choice of boundary conditions. Furthermore, the error function is linear in the elastic constants, which may be computed easily via a matrix inversion. This framework lends itself naturally to a physical interpretation of the results in terms of linear combinations of eigenmodes, yielding new sets of modes and associated combined mode shapes in which the elastic constants are completely uncoupled. Several numerical benchmark tests and experimental cases are treated in detail, highlighting the reliability of the proposed methodology in cases of interest in acoustics and musical acoustics
Experimentally-tuned Synthesis Of A Thin Plate
Get PDFThe numerical simulation of acoustic instruments and devices is a growing subject of research. Applications range from model-aided instrument making, to virtual instrument and effect design, to virtual reality applications. A faithful reproduction of the underlying system may be realised via signal-based analysis and resynthesis, starting usually from a recorded sample. Model-based synthesis, on the other hand, allows to reproduce the dynamics of common objects such as strings, bars and plates by setting a few physically meaningful parameters feeding a mathematical model. The latter allows far greater flexibility in terms of control and design, but often lacks the realism of the former. This work investigates the possibility of tuning a physical model using experimental data. The system considered here is a cantilever metal plate struck with a hammer. The physical model is derived from a modal decomposition of the Kirchhoff plate equation. A preliminary estimate of the unknown plate's rigidity constant is carried out first, via the measurement of the first eigenfrequency. Then, the finite difference scheme is used to solve the eigenvalue problem over a fine grid with the computed rigidity constant, and the modal shapes are then stored along with the modal frequencies. Experimental data are collected from a laboratory experiment, and a comparison of the experimental frequencies against the model's eigenfrequencies is carried out. The modal equations obtained from the difference scheme are then adjusted to compensate for the errors in the eigenfrequencies. Experimental decay times are also implemented in the scheme. Tuned numerical impulse responses at three different combinations of input and output locations are then computed and compared to the experimental responses, showing a high degree of accuracy
FAST ESTIMATION OF WOOD ELASTIC CONSTANTS USING LEAST-SQUARES
Get PDFMechanical properties of materials represent, among others, one of the most relevant topics in musical acoustics. Such features can be used to better understand the behaviour of musical instruments or to evaluate the impact of design interventions, and build accurate physical models. In this regard, this paper aims to introduce an accessible procedure to estimate the elastic constants of wood using a thin plate. Compared to previous methods in the literature, the inverse problem is here formulated linearly in the rigidity constants, thus allowing a unique solution via a matrix inverse, and using a least-squares formulation. The reliability of the method is numerically proven in a number of examples
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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
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