1,720,954 research outputs found
The development of an acoustic navigational aid for autonomous underwater vehicles
No full textThis thesis summarises the research contribution to an ongoing project that is concerned with the development of a correlation velocity log (CVL), aimed specifically at autonomous underwater vehicles. The main objective of this research has been to improve the performance of a prototype CVL instrument that has been developed through collaboration between Chelsea Technologies Group, H Scientific Ltd and the University of Southampton.A CVL is an acoustic-based navigational aid that uses a transmitter and an array of receiving elements in order to estimate velocity through the water relative to acoustic scatterers. A pair of short-duration acoustic pings is projected vertically downwards towards the seabed. Similarities in the echoes detected across the receiving array can be used together with knowledge of the acoustical array spatial relationships to estimate velocity. Similarity between received signals is determined by calculating a correlation coefficient between all combinations of receivers. The spatial distance separating the pair of receivers exerting the highest correlation is used together with the interpulse interval in order to estimate velocity of the craft.The first half of this research work has been concerned with analysing existing data collected during past trials of the prototype system; in particular, the effect of phase differences across the acoustic receiver array has been investigated in depth. Analysis of the phase showed that sampling delays within the processing system and a phase inversion of one receiver's signals were causing unexpected phase variations across the acoustic array. Left uncorrected, these phase errors were undoubtedly reducing the effectiveness of the peak finding routines in the processing of data. Compensation algorithms have been derived to correct the phase within the DSP.The second major section of work has concentrated on investigating peak estimation techniques for peak finding on a correlation surface that is central to the operation of the CVL. The methods compared include the indices of the highest point in the dataset, fitting of an axisymmetric quadratic model using either least squares or a non-linear, iterative implementation of maximum likelihood estimation, radial basis functions and Gaussian Processes. Numerical simulations demonstrate that radial basis functions provide the most robust method for peak estimation in this context. However, for simplicity of implementation on the DSP system, least squares remains the favoured method, offering respectable peak estimation accuracy throughout the measurement area
An investigation into the effect of fabrication parameter variation on the characteristics of screen printed thick film Ag/AgCl reference electrodes
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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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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