1,720,962 research outputs found
SANS/VSANS investigation of porosity microstructure in rocks from a natural CO2 reservoir
No full textCarbon capture and storage (CCS) is considered a valid option to reduce the CO2 concentration in atmosphere. The gas is collected from industrial plants, then injected and stored underground in geological reservoir. A very wide range of information about chemical-physical characteristics of the sequestration site is therefore needed and, among them, data on porosity microstructure are crucial. Part of the processes which affect micro-porosity and act during and after the rocks formation can be reconstructed by studying the micro-porosity features. We have therefore performed a couple of SANS and VSANS experiments on rocks coming from a CO2 reservoir (which represents a natural analogue of a CCS site) in order to define the role and the possible effects of CO2 alteration in determining the micro-porosity and to check the sealing potential of rocks overlying the reservoir, which act as a barrier with respect to CO2-rich gas. The collected data are expected to be beneficial for developing theoretical model about the effects of CO2 sequestration in deep geological reservoirs
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
SANS/VSANS investigation of the porosity microstructure in rocks from a natural CO2 reservoir
No full textSequestration of CO2 in deep geological reservoirs represents one of the potential methods to reduce anthropogenic emissions into the atmosphere. In the long term the injected CO2 dissolves into the local formation of rocks and, when present, in saline deep aquifers, participating to a variety of geochemical reactions. The overall impact of these processes produces changes in mineralogy, texture, permeability and porous structure of the rocks, to a level which depends on the different lithologies present in the rocks.
Mineralogical changes can be investigated by considering what occurs in rocks and minerals with natural CO2 accumulations, as analogues for geological sequestration. Also computer simulations, based on thermodynamics, kinetics and geochemical modeling [1, 2], can be beneficial. On the other hand, reliable data concerning the porous structure, which is so important to trap CO2, can be hardly extracted from computer simulations.
In this context a valuable help can be provided by Small and Very Small Angle Neutron Scattering techniques (SANS and VSANS, respectively): they have been indeed demonstrated to be powerful tools for the determination of the microstructure and porosity of rocks from Ångstrom to millimeter sizes [3], proofing also the existence of fractal dimensions for the volume and surfaces interfaces between pores and rocks.
Here we present the preliminary results of a SANS/VSANS investigation on rocks pertaining to a geological context (located in Eastern Tuscany, Central Italy) featured by a deep geological gas reservoir. The former reservoir was intercepted by a bore-well drilled in ’80 by ENI and is presently hosting 700 bar of supercritical CO2. Texture and mineralogy of volcanic rocks samples, from drill cores corresponding to the top of the reservoir, were found to be heavily modified by the interaction with CO2-rich fluids.
The combined neutron experiments, performed using the PAXE and G5bis diffractometers at LLB (Saclay, F), allowed to approximately investigate pore sizes ranging from ∼ 60 nm to ∼ 6 μm. Samples of host rocks (from drill core) and a selection of possible analogues of the same volcanic rocks, unaffected by CO2 presence, were chosen for the experiments together with samples of rocks, from outcrops, corresponding to the geological layers the characteristics of geological layers overlying the reservoir. Globally these rocks are representative of a wide spectrum of different lithologies (as limestones, marls, evaporitic deposits bearing gypsum and volcanic rocks with intermediate-acid composition).
The information provided by these experiments must still be fully analyzed and integrated with other data (e.g. chemical composition of rocks and fluids [4]) in order to get a better understanding of: i) the role and the possible effects of CO2 in determining the micro-porosity of these host rocks, and ii) the sealing effect of the sedimentary rocks overlying the reservoir which act as a barrier with respect to the CO2-rich gases.
References
[1] Zhu C. and Anderson G., 2002 Environmental Applications of Geochemical Modeling, Cambridge University Press, Cambridge, UK, 284 pp.
[2] Cantucci B, Montegrossi G., Vaselli O., Tassi F., Quattrocchi F., and Perkins E.H., 2009 Geochemical modelling of CO2 storage in deep reservoirs: The Weyburn Project (Canada) case study. Chemical Geology, 265 (1), 181-197.
[3] A.P. Radlinski, 2006 and reference therein, in Neutron Scattering in Earth Sciences, Reviews in Mineralogy & Geochemistry, 63, pp. 363-397.
[4] Bicocchi G., Montegrossi G., Ruggieri G., Buccianti A. and Vaselli O. (2011). Modeling composition of Ca-Fe-Mg carbonates in a natural CO2 reservoir. In: Egozcue, J.J., Tolosana-Delgado, R. and Ortego, M.I. (eds.). Codawork11 Proceedings, 16 p
Physical-chemical characteristics of CO2 altered rocks
No full textCarbon capture and storage (CCS) is considered a valid option to reduce the CO2 concentration in atmosphere. The gas is collected from industrial plants, then injected and stored underground in geological reservoirs. A very wide range of information about chemical-physical characteristics of the sequestration site is therefore needed and, among them, data on porosity microstructure are crucial. Part of the processes which affect micro-porosity and act during and after the rock formation can be reconstructed by studying micro-porosity features. In this work, different experimental approaches have been combined to reconstruct the mineral association, bulk chemistry and microporous structure of rocks from a natural CO2 reservoir (which represents a natural analogue of a CCS site). The fluid reservoir, i.e. Caprese Reservoir, was discovered while drilling PSS1 borehole in San Cassiano Basin (Eastern Tuscany, Central Italy) and consists of sedimentary rocks (Burano Fm.) interbedded with altered volcanic rocks, its depth being about 3,300 m with respect to the land surface. At 3,700 m depth fluid pressure and temperature are 700 bars and 120 °C respectively, with a calculated density for CO2 of 860 Kg·m-3. The study was conducted on the volcanic rocks altered by CO2 from the PSS1 wellbore drill cores and on some volcanic rocks unaffected by the presence of CO2. Lastly, rocks from the Burano Formation, unavailable from PSS1, have been sampled on outcrop. Drill core samples corresponding to the depth 3,864-3,871 m with respect to PSS1 log, have been investigated with SEM-EDS, XRD, EMP, ICP-MS and LOI and for the mineralogical and chemical characterization. The SANS/VSANS experiments at LLB (Saclay, France) served for microporous structure investigation of PSS1 rocks, volcanic rocks from Eastern Alps (IG1) and the Albani Hills (IG2 and IG3) unaffected by CO2 and Burano Formation
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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