1,720,957 research outputs found
Lithofacies and depth dependency of thermo- and petrophysical rock parameters of the Upper Jurassic geothermal carbonate reservoirs of the Molasse Basin
No full textIn the early stages of hydrothermal reservoir exploration, the thermo-physical characterisation of the reservoir is accomplished by evaluating drilling data and seismic surveys. Especially in carbonate reservoirs, the distinction of different facies zones and heterogeneities in general is very complex. For economic reasons a sufficiently high flow rate toward the production well and an according high fluid temperature is necessary. For reservoir predictions and modelling, geothermal parameters such as permeability, thermal conductivity/diffusivity, and specific heat capacity have to be quantified. The thermophysical parameters are facies related. The application of a thermofacies classification to Upper Jurassic limestones serves to understand the heterogeneities and to identify production zones. Outcrop analogue studies enable the determination and correlation of facies related thermophysical parameters and structural geology data and thus the geothermal exploration concept becomes more precise and quantitative. The analogue outcrops of the Swabian and Franconian Alb represent the target formations of Upper Jurassic carbonate reservoirs in the adjacent Molasse Basin. These limestone formations contain the main flow paths through fractures, faults, and characteristic of limestone formations also through karstification. The type and grade of karstification is also facies related. In general, the matrix permeability has only a minor effect on the reservoir's sustainability except for some grainstones and dolomitised zones with higher porosities and permeabilities. Permeabilities range from 10 to 10 m (0.001 mD to 100 mD). The permeability range of mud- and wackestones is about the same. A high variation of thermophysical parameters is recognised within individual facies zones or stratigraphic units. Mud- and wackestones show thermal conductivities around 2 W/(mK), whilst mudstones have lower thermal conductivities than wackestones. The thermal conductivities of massive reefal limestones show values of 1.8 to 3.9 W/(mK). Secondarily silicified reefal limestones and dolomites show the highest values of thermal conductivity. These parameters determined on oven-dried samples have to be corrected for water-saturated rocks under the according temperature and pressure conditions using transfer models. A comparison of calculated reservoir properties with measurements from deep drill cores confirms a good correlation. Based on the investigation of the matrix parameters in combination with reservoir transfer models, the reservoir prognosis and numerical simulation can be improved. The facies related characterisation and prediction of reservoir formations is a powerful tool for the exploration, operation, extension and quality management of geothermal reservoirs in the Molasse Basin
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
Upscaling thermal conductivities of sedimentary formations for geothermal exploration
No full textAn important issue in the numerical simulation of geothermal reservoirs is the problem of scales. Data are collected at a scale usually smaller than the one used to discretise the sedimentological units in the numerical model. For instance, thermal conductivities sampled from field scale cores have measurement support in the order of centimeters to meters, whereas numerical models for heat flow require conductivities representative of scales ranging between tens to hundreds of meters. We present a study aimed at demonstrating the upscaling of thermal conductivities. Based on the spatial characteristics of a large sample data set of thermal conductivities of permo-carboniferous sedimentary rocks, 10 different realizations of the system are randomly generated at a fine scale of resolution and are then upscaled to four different resolutions using diverse averaging procedures (based on arithmetic, geometric, or harmonic averaging) as well as renormalization. Results show that upscaling based on harmonic averaging of local values is superior in reproducing the original values while renormalization gives the poorest results. Generally it is demonstrated that the specific kind of upscaling has only a small impact on the resulting temperature distribution. Due to the diffusive character of heat conduction all results tend towards the arithmetic mean value associated with the data
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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