1,720,954 research outputs found
Optimisation of Near-Surface Seismic Reflection Data
No full textGeological ground models of the shallow subsurface, incorporating stratigraphic interpretations and physical properties are used for applications such as offshore engineering foundation design, geohazard assessment and carbon capture and storage monitoring. In the past they have relied on integrating qualitative interpretations of seismic imagery with 1D in situ geotechnical measurements, limiting the ability to capture lateral variations in physical properties. Ultra-High Frequency Multi-Channel Seismic (UHFMCS; 0.2 - 4.0 kHz) reflection data potentially enables quantitative characterisation of shallow sediments at resolutions < 1 m vertically and 5 m horizontally. However, this potential is limited by conventional processing workflows and imaging strategy. In this thesis I focus on optimising the entire seismic processing workflow to improve both the seismic images used in a ground model and the ability to estimate physical parameters from the data. Firstly, I develop a new method to define source-receiver geometries. I determine relative source-receiver positions using first break travel-times in a hierarchical Genetic Algorithm (GA) inversion. I test the method against synthetic examples, allowing assessment of noise contamination effects, before a real data case study demonstrates the ability of the GA to correctly position traces. Secondly, I use a UHF-MCS dataset acquired in the East Solent, UK, to understand how imaging technique and velocity modelling methodology affect physical property estimations. I compare interval velocities from conventional NMO-Semblance time-domain velocity picking against a layer stripping depth migration and use empirical relationships to derive porosity from the velocity models. Uncertainty analysis demonstrates improved reliability of physical property estimations , as well as higher quality seismic images from pre-stack depth domain velocity modelling and imaging strategies. Finally, I apply these approaches to a commercial dataset from the Dutch Sector of the North Sea, using UHF-MCS data to quantitatively evaluate a strongly variable stratigraphic boundary. Implementing seismic quality factor and post-stack acoustic impedance inversions alongside lithostratigraphic interpretations, the amplitude anomalies at this stratigraphic boundary are interpreted to over-pressures generated by the trapping of pore fluids as a result of dewatering during the Saalian Glacial Complex. The implication of these findings on offshore engineering design are then discussed.<br/
Dataset in support of the Southampton doctoral thesis 'The optimisation of near surface seismic reflection data'
No full textSupporting Data for PhD Thesis.
This is split into the three scientific Chapters:
- Chapter 2 - Modelling the Acquisition Geometry of Near-Surface Marine Seismic Reflection Data
- Chapter 3 - The importance of Velocity Modelling and Uncertainties in Deriving Physical Properties for the Marine Near-Surface
- Chapter 4 - A Quantitative Geophysical Analysis of Amplitude Anomalies in Hollandse Kust West
Within each of these you will find the relevant raw & processed data (if relevant), Parameter Grids, and additional datasets that were used in the thesis and that are able to be shared. </span
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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