1,721,162 research outputs found
An iterative procedure for the simulation of the steady-state fluid flow in rock fracture networks
No full textEquivalent pipe network (EPN) modelling is widely accepted as an effective technique for modelling fluid flow through fracture networks in rock masses. The major advantages of this approach are its simplicity and computational efficiency, which make it capable of dealing with complex, reservoir-scale problems. The major disadvantage, however, is that the derived flow model depends primarily on the pipe network used and the construction of a representative pipe network model is still very challenging, particularly for large and complicated fracture networks. Existing approaches for constructing EPN are primarily geometrical and do not take account of flow kinematics within fracture networks. Consequently, the flow model obtained is less realistic due to the unavoidable subjective assumptions involved in pipe connections. This paper describes a recently proposed iterative process for deriving a more realistic flow model by taking into account the flow kinematics within the fracture network while constructing the EPN model. To do so, the connection pipes are based on the flow sources and sinks of fracture intersection traces on each individual fracture. However, the input in this case is also part of the solution output and therefore the process must be iterated until the model converges to a stable solution. A simple 3D fracture network is used to cross-validate the proposed approach against a COMSOL finite element model. Finally, as a case study, the method is applied to the reservoir-scale flow analysis of the Habanero geothermal field in the Cooper Basin of South Australia
A simplified equivalent pipe network approach to model flow in poro-fractured rock masses
No full textAssessment of flow through fractured porous rock masses is a common problem in many engineering applications including hydrogeology, in-situ mineral recovery, hydro-geothermal resources, mining and oil and gas extraction. In all these applications, flow through the fracture network within the rock mass is, in general, dominant but the contribution to the overall flow from the flow through the intact rock will increase as the permeability of the intact rock increases. Therefore, in general, flow through both the fracture network and the porous rock must be considered simultaneously in order to derive a realistic flow model. The most common numerical approach to solving this problem is to use the dual permeability model in which the fracture network and porous rock are treated as two separate permeable media interacting by means of an exchange term between them. In this approach, the fracture network is usually grossly over-simplified, and the connectivity of the fractures is not directly considered in establishing the dual permeability model. In this work, we present a simple equivalent pipe network approach which solves the problem by considering the connectivity of the fracture network whilst, at the same time, taking into account the permeable nature of the intact rock. The proposed method has the additional benefit of reducing computing costs. A simple example is used to demonstrate the application of the proposed approach
An improved pipe network model for simulation of fluid flow through discrete fracture networks
No full textA common approach to modelling fluid flow through discrete fracture networks is to represent the fracture network by an equivalent pipe network model. The major advantage of this approach is its simplicity and computational efficiency, which enables it to deal with complex, reservoir-scale problems. However, the derived flow model depends primarily on the pipe network used and the construction of a representative pipe model is still a very challenging issue, particularly for large and complicated fracture networks. An iterative process was proposed recently to derive such a realistic pipe network model and the work reported in this paper is an extension of that approach with an improvement on how pipes are re-connected during the iteration process to better represent the reality of flow patterns. In particular, the source and sink traces on each fracture are re-evaluated using the boundary element method during each iteration step. As a case study, the proposed approach is applied to the flow analysis of the Habanero geothermal field in the Cooper Basin of South Australia
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
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