1,720,981 research outputs found
A new method for 2D stochastic inverse modeling in Magnetotellurics: application to the Larderello-Travale geothermal field and novel results from 3D inversion
Full text linkL'abstract è presente nell'allegato / the abstract is in the attachmen
Thermal impact assessment of Groundwater Heat Pumps (GWHPs): modelling assumptions and key parameters
No full textThe increasing diffusion of Groundwater Heat Pumps (GWHPs), especially for large buildings in urban areas, needs to be managed in order to avoid reciprocal impacts between neighbouring installations and on other water uses. For this reason, a thorough hydrogeological characterisation and a rigorous modelling of the subsurface thermal impact of GWHPs is required; however, this subject has been addressed by a few studies only, among which those reported in Refs. [1-4].
We present a comprehensive sensitivity analysis, based on numerical flow and heat transfer simulations carried out with the software FEFLOW, in order to assess how the thermal plume size is affected by the aquifer’s hydrodynamic parameters, the subsurface thermal properties, the thickness of the vadose and saturated zones, and by the thermal load exchanged [5]. In particular, we addressed the plume length, width and their temporal evolution in the long term. The results of this analysis identify which parameters most affect the propagation of the thermal plume, and hence can most contribute to possible simulation errors if not properly assigned. In addition, we addressed a number of different ssumptions in the modelling of GWHPs. The heat exchange between the aquifer and the atmosphere strongly impacts on the plume length, and hence GWHPs should be modelled in 3D rather than 2D. Using the yearly average of a thermal load dramatically reduces calculation times, but may lead to a severe underestimation of the plume width. An acceptable estimation of the plume width can be performed with analytical formula by Banks [1], while this is not possible for the plume length. This work, carried out in the framework of the GRETA project [6], provides a methodological basis for the assessment of the thermal footprint of GWHPs, and hence on their sustainability in densely inhabited areas
Joint optimization of geophysical data using multi-objective swarm intelligence
Full text linkThe joint inversion of multiple data sets encompasses the advantages of different geophysical
methods but may yield to conflicting solutions. Global search methods have been recently
developed to address the issue of local minima found by derivative-based methods, to analyse
the data compatibility and to find the set of trade-off solutions, since they are not unique. In
this paper, we examine two evolutionary algorithms to solve the joint inversion of electrical
and electromagnetic data. These nature-inspired metaheuristics also adopt the principle of
Pareto optimality in order to identify the result among the feasible solutions and then infer the
data compatibility. Since the joint inversion is characterized by more than one objective, we
implemented the algorithm multi-objective particle swarm optimization (MOPSO) to jointly
interpret time-domain electromagnetic data and vertical electrical sounding. We first tested
MOPSO on a synthetic model. The performance of MOPSO was directly compared with that
of a multi-objective genetic algorithm, the non-dominated sorting genetic algorithm (NSGAIII),
which has often been adopted in geophysics. The adoption of MOPSO and NSGA-III
enabled avoiding both simplification into a single-objective problem and the use of a weighting
factor between the objectives. We tested the two methods on real data sets collected in the
northwest of Italy. The results obtained from MOPSO and NSGA-III were highly comparable
to each other and largely consistent with literature findings. The MOPSO performed a rigorous
selection of the best trade-off solutions and its convergence was faster than NSGA-III. The
analysis of the Pareto Front reported data incompatibility, which is very common for real data
due to different resolutions, sensitivities and depth of investigations. Notwithstanding this,
the multi-objective optimizers provided a complementary interpretation of the data, ensuring
significant advantages with respect to the separate optimizations we carried out using the
single-objective particle swarm optimization algorithm
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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