1,720,996 research outputs found
A magnetotelluric experiment around St. Austell, Cornwall
Get PDFIn this BGS Open Report we describe the results of a pilot study assessing the potential of the magnetotelluric (MT) method to characterize geothermal reservoirs at depth when the target site is in a semi-urban environment. During an MT survey, the natural variations of the electromagnetic field of the Earth are measured at the field site for time windows of a few hours up to a couple of days. As a passive geophysical technique, the data quality is dependent on the in-situ electromagnetic noise levels. The noise come from technological infrastructure that dominates the landscape of modern Britain such as power lines, high voltage transformers, electric fences, radio towers, electrified railways and gas pipeline protection systems. In the absence of artificial noise, the MT method can sample the shallow and deep subsurface of the Earth down to the lower crust and mantle depending on the frequency of the measured signal. MT images the bulk electrical conductivity of the rocks and can therefore indicate the presence of fluids at depth. For deep geothermal exploration, MT has been identified as one of the few geophysical techniques able to help characterise geothermal host rocks and zones of enhanced permeability and porosity which are necessary for the fluid circulation of an enhanced geothermal system.
Deep geothermal exploration in the UK has, so far, been limited to the granites of Cornwall which are known to have relatively high heat flow. Along with a strong legacy knowledge of the geology of the subsurface these have encouraged two deep geothermal drill projects. At the Eden Geothermal site close to the Eden Project in St Austell, a 5,277 m deep borehole was drilled into the St Austell granite to intersect with a known geologic fault zone, the NNW-SSE striking Great Cross-Course (GXC) Fault, where the circulation of geothermal fluids in a closed loop system was deemed possible. The drilling was partly sponsored by the European Regional Development Fund and designed as both a research facility and to provide green energy to the Eden Project and adjacent businesses. The position and extent of the fault zone at depth was not known and previous geophysical surveys had been limited to very shallow depths. Seismic monitoring has been an ongoing component of the drilling and ensuing pump testing.
During a 10-day field campaign in March 2023 a team from BGS were able to collect broadband MT data at 30 sites in the St Austell area and one remote site in Bodmin Moor to help improve data quality through remote referencing time-series processing techniques. Data collected very close to the drill site and at some locations close to town centres have low quality, but overall data quality was sufficient to allow modelling of the electrical properties at depth. The derived MT impedance tensors were used to construct a 3D model of the area which has low spatial resolution but clearly shows that MT data can image the local geology at depth. The St Austell granite is characterized by high resistivities, whereas the onshore sediments and metasediments surrounding the intrusion have lower resistivities. Some vertical structures of lower resistivity within the granite were identified and are carefully investigated.
Overall, the use of the MT method for the characterisation of geothermal reservoirs in granitic bodies is confirmed in this study. Further data collection and modelling is recommended to improve the spatial resolution at depth
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
Validation of geomagnetically induced current modelling code
Get PDFA paper by Horton et al. (2012) details a test grid containing 8 substations with 15 transformers connected by 15 lines. The paper gives detailed information about location, resistances and connections including features such as capacitors, delta and composite transformer types. The model output for 1 V/km in the north-south and east-west directions are provided. In early 2017, the BGS Geomagnetism team produced an equivalent model using the Nodal Admittance Method and proved their model to be consistent with Horton et al. This report outlines our approach and results
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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