1,721,054 research outputs found
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
Using reflected seismic waves to estimate rheological properties of the fluid-mud layer for port applications
No full textCurrent Port of Rotterdam procedure is to define the nautical depth based on the density of a fluid-mud layer, that settles at the bottom of the port. Rheological parameters could be an improved indicator for nautical depth and decrease the frequency and cost of dredging. I investigate the use of reflected seismic waves to derive in situ rheological parameters. I model a simplified port profile to investigate the effects of o_set on the types of seismic reflections acquired. Four models of how the density of the fluid-mud layer varies with depth are proposed. I undertake simple laboratory experiments to measure the effects of consolidation time, density and frequency has on the seismic velocities of the fluid-mud layer. From these laboratory experiments I calculate the shear modulus, bulk modulus, Young's modulus and Poisson's ratio for the fluid-mud layer of varying densities. Reflected seismic-wave velocities prove to be promising in deriving in situ rheological parameters, elastic constants and, potentially, viscosity.Applied Geophysic
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
Combining Geophysics and Basin Modeling to Develop a Thermal Model in an Offshore Block, Mexican Gulf of Mexico: Constraining Source Rock Maturity Through OAT Sensitivity Analyses of Key Inputs
No full textThe recent discovery of the Zama field in offshore Sureste Basin in the southern Gulf of Mexico has piqued interest in the Mexican petroleum industry regarding the hydrocarbon potential within the region. In this study, a deposition-only thermal model was developed in an area of interest (AOI) in this region. Using structural input obtained from seismic interpretation conducted in Petrel©, the model was constructed and simulated in PetroMod© to acquire initial estimates of the maturity of the Tithonian J100 source rock in the AOI in terms of the maturity parameters Vitrinite Reflectance (%Ro) and Transformation Ratio (TR). A one-at-a-time (OAT) sensitivity analysis approach was also undertaken to assess the impact of uncertainties in some inputs in isolation on the output maturity in order to identify key uncertain input parameters. Based on the modeling results, at the C-1 well location of interest within the AOI, the source rock was simulated to be within the wet gas generation window based on simulated %Ro values in the present, having emerged into oil window between 41 - 27 Ma (late Eocene-Oligocene) and into the wet gas window between 6 - 0.5Ma (late Miocene-Pleistocene). Across the wider AOI, present-day %Ro values indicate the predominant presence of late oil to wet gas generation windows, with most of the source rock across the AOI having emerged into the oil generation window between 23 Ma and 11.6 Ma (early to middle Miocene). The highest uncertainties in simulated %Ro values were associated with uncertainties in the Bajocian (J60) autochtonous salt sequence thickness distribution and with the maturity models used for model simulation. At the C-1 well location, TR values of 95% to near 100% in the present indicate that most of the kerogen (source rock organic matter) has already been converted into hydrocarbons, with kerogen conversion initiated between 55 - 48 Ma at the location. Across the wider AOI, average present-day TR values in the range of 81 - 97% were simulated. The highest uncertainties in simulated TR values were also associated with uncertainties in the Bajocian (J60) autochtonous salt sequence thickness distribution, and with the source rock maturation kinetics input used for model simulation. The timing of maturation of the J100 source rock at the C-1 well location - assumed to have been constrained by the OAT sensitivity analyses results for simplicity - in relation to the timing of other petroleum system elements and processes indicated by literature, suggests that hydrocarbon accumulations charged from the Tithonian source rock in the reservoir intervals in the well vicinity are possible i.e. presence of hydrocarbon accumulations cannot be ruled out based only on maturation timing considerations.Applied Geophysics | IDEA Leagu
Investigation of geothermal potential in lower devonian formations of Rhenish Maassif, Eifel region, Germany
Get PDFLAUREA MAGISTRALEQuesto studio esplora il potenziale geotermico delle arenarie del Devoniano inferiore nella regione dell'Eifel, Massiccio Renano, Germania, analizzando le loro proprietà petrofisiche e caratteristiche strutturali. Attraverso indagini sul campo, test di laboratorio e confronti con altri progetti geotermici, la ricerca valuta l'idoneità della produzione di energia geotermica in questa regione. I risultati mostrano che la conduttività termica delle arenarie è favorevole al trasferimento di calore, con valori tra 3,913 e 5,640 W/m·K (a secco) e 4,524 e 6,19 W/m·K (saturato), mentre la porosità (2–3,5%) e la permeabilità (4,80 × 10−19 - 5,37 × 10−18 m2) sono molto basse, rendendo il flusso di fluido fortemente dipendente dai sistemi di fratture e faglie. L'analisi strutturale conferma che la Zona di Shear di Monschau (MSZ) e le faglie normali e di sovrascorrimento vicino ai punti di campionamento possono migliorare la permeabilità nelle formazioni di Rurberg, Monschau e Heimbach, ma a causa delle incertezze tra le condizioni superficiali e sotterranee, i sistemi di fratture devono essere studiati con metodi più precisi per valutare la possibilità di implementare sistemi geotermici potenziati (EGS - Enhanced Geothermal Systems). Il confronto con studi geotermici in Germania e Lussemburgo mostra che, sebbene le proprietà termiche delle arenarie dell'Eifel siano promettenti, la bassa permeabilità rende le fratture un fattore cruciale per la fattibilità geotermica. Questo studio conclude che l'Eifel ha un potenziale geotermico, ma il successo del progetto dipende dalla presenza di fratture aperte e connesse o dall'uso di tecniche di stimolazione artificiale del serbatoio. Per ottimizzare lo sviluppo geotermico nell'area, future ricerche dovrebbero concentrarsi su imaging geofisico avanzato, analisi dello stato di sollecitazione, modellazione idrotermale e valutazioni economiche e ambientali.This research analyzes the petrophysical characteristics and structural features of Lower Devonian sandstones in the Eifel region of the Rhenish Massif, Germany, to determine their geothermal potential. By laboratory testing, field investigation, and comparisons with other geothermal projects, the study evaluates the potential of geothermal energy production in this area. The results show that the thermal conductivity of the sandstones is appropriate for heat transfer, with values ranging from 3.913 to 5.640 W/m·K (dry) and 4.524 to 6.19 W/m·K (saturated). However, porosity (2–3.5%) and permeability (4.80 × 10−19 to 5.37 × 10−18 m2) are very low, that means fluid flow strongly depend on fractures and faults systems in this region. Structural investigation confirms that the Monschau Shear Zone (MSZ) with NW-SE trending, normal faults and thrust faults near the sampling points can have an important effect in enhancing permeability in formations including Rurberg, Monschau and Heimbach Formation. But due to the uncertainty and limitations between the surface and underground condition, the fracture systems should be investigated with precise methods to know the possibility of using EGS (Enhanced Geothermal Systems). Comparisons with geothermal studies in Germany and Luxembourg show that while the thermal properties of Eifel sandstones are favorable, their lower permeability makes fractures even more important for geothermal viability. Based on this study, the Eifel area has geothermal potential, but the existence of open, connected fractures or artificial reservoir stimulation is necessary for being a successful project. Future research should focus on detailed geophysical imaging, stress analysis, and hydrothermal modeling, as well as economic and environmental feasibility assessments, in order to optimize geothermal energy development in the study area
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
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