1,721,152 research outputs found
Adaptive approaches to signal enhancement and deconvolution (with particular reference to reflection seismology)
No full textDeconvolution and signal enhancement are important aspects of digitalsignal processing. Many techniques have been developed to achieve thesetwin aims, the vast majority however were designed to deal with stationarysignals. However, many practically occurring signals are significantlynon-stationary and these techniques are rendered at least partiallyineffective.This thesis is devoted to the study of adaptive techniques, these form aclass of methods which are specifically designed to give the flexibilityto deal with non-stationarity. The thesis demonstrates the value ofadaptive approaches to problems of deconvolution and signal enhancement,particularly in reflection seismology. Adaptive processes are dividedinto two classes - modelled and empirical. The power of both theseapproaches is demonstrated by concentrating primarily on one algorithm ofeach class. In the case of the modelled approach the technique chosen isa recent approach to deconvolution based on the methods of optimal control.The method is redeveloped in discrete-time, the theory is extended toinclude the important problem of noise reduction in deconvolution, and forthe first time, the method is applied to physical problems. The principalapplication is to the deconvolution of seismic data incorporating bothstationary and non-stationary models. A second application is to thedeconvolution of data derived from a velocity meter.The empirical approach to adaptive processing is illustrated by the so-calledLMS (least mean-square) algorithm. The theory of this method isrationalised and extended both for broadband inputs, particularly for theimportant area of non-stationary random processes, and for narrowband inputs.Two new configurations of the LMS algorithm are introduced for signalenhancement. One, dubbed the generalised comb filter is designed for theenhancement of signals which may be considered to consist of a series ofslowly time-varying wavelets of unknown form, recurring at roughly constantintervals and embedded in random noise with unknown properties. The theoryof this method is developed and the technique is applied to the enhancementof voiced speech and to the enhancement of seismic signals. This seismicenhancement has two forms - one for highly reverberant single-channelseismic data, and the other for enhancing multi-channel data. The secondnovel configuration of the LMS is in the form of a sparse adaptive filter,that is one with relatively few coefficients in relation to its length,with the objective of signal enhancement by cancellation of multipleinterfering sinusoids. This technique is also applied to the problem ofspeech enhancement
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
Conservatism, disclosure and the cost of equity capital
No full textThis study seeks insights into the economic consequences of accounting conservatism by examining the relation between conservatism and cost of equity capital. Appealing to the analytical and empirical literatures, we posit an inverse relation. Importantly, we also posit that the strength of the relation is conditional on the firm’s information environment, being the strongest for firms with high information asymmetry and the weakest (potentially negligible) for firms with low information asymmetry. Based on a sample of US-listed entities, we find, as predicted, an inverse relation between conservatism and the cost of equity capital, but further, that this relation is diminished for firms with low information asymmetry environments. This evidence indicates that there are economic benefits associated with the adoption of conservative reporting practices and leads us to conclude that conservatism has a positive role in accounting principles and practices, despite its increasing rejection by accounting standard setters
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
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