1,720,963 research outputs found
Mapping Radioactivity from Monitoring Data: automating the Classical Geostatistical Approach
No full textIn the context of a comparison of spatial prediction algorithms, we applied the classical geostatistical approach to see how well it would automate, and how well it performed in case of an unexpected anomaly. In case of a test without anomaly, the method performed well. In the anomaly case, automatic variogram modelling was hindered seriously, and in terms of RMSE best results were obtained by using the variogram from the test data without the anomaly. Although the 10 days of available training data showed a strong temporally persistent spatial pattern, cokriging did not improve predictions
The Challenge of Real-time Automatic Mapping for Environmental Monitoring Network Management
No full textThe automatic interpolation of environmental monitoring network data
such as air quality or radiation levels in real-time setting poses a number of practical
and theoretical questions. Among the problems found are (i) dealing and communicating uncertainty of predictions, (ii) automatic (hyper)parameter estimation, (iii) monitoring network heterogeneity, (iv) dealing with outlying extremes, and (v) quality control. In this paper we discuss these issues, in light of the spatial interpolation
comparison exercise held in 2004.JRC.H.4 - Transport and air qualit
The challenge of real-time automatic mapping for environmental monitoring network management
Get PDFThe automatic interpolation of environmental monitoring network data such as air quality or radiation levels in real-time setting poses a number of practical and theoretical questions. Among the problems found are (i) dealing and communicating uncertainty of predictions, (ii) automatic (hyper)parameter estimation, (iii) monitoring network heterogeneity, (iv) dealing with outlying extremes, and (v) quality control. In this paper we discuss these issues, in light of the spatial interpolation comparison exercise held in 2004
Automatic Mapping in Emergency: A Geostatistical Perspective
No full textIn the case of a severe nuclear accident, radionuclides may be released into the
atmosphere and contaminate large areas. Essential information for decision making
and further modelling are maps that describe the radiological situation. Radiological
maps are obtained after a spatial interpolation process that converts local
measurements into information continuous in space. Ideally, the mapping process
should be fully automatic and provide information in real time. It is the purpose of
this paper to discuss results obtained from two statistical exercises that addressed the
issue of automating the spatial interpolation step both in routine and emergency
situations. The first exercise addressed mainly the current state of the art of mapping
deposited radioactivity following an accident in wet conditions and explored the
impact of human factors on the results obtained. The second exercise, conceptually
similar to the first one, involved real gamma dose rate measurements to address
specifically the automation issue. To further address the response of these mapping
algorithms in emergency situations, simulated data have also been used to explore the
impact of extreme values on the process. It is shown that if results tend to be similar
in routine situations, independently of the choice of algorithms, many obstacles still
remain before we can rely on fully automatic mapping systems in emergency
situations, especially during the early and critical stage of an accident when
measurements on the contamination are sparse.
Keywords: nuclear accident, decision making, mapping, GIS, monitoring networks,
spatial interpolationJRC.H.4 - Transport and air qualit
Decision Making and Radiological Maps: Understanding Map Uncertainties in Emergency
No full textEssential information for decision makers in the frame of a radiological emergency response is expected to be derived from radiological maps. In the case a spatial interpolation step is needed, one has to choose among many algorithms that may generate very different results. The maps produced can be of mainly two forms: they can present either estimates of the radiological variable at unsampled locations, or estimates of the local probability of the variable to exceed a threshold (risk maps) defined usually by a regulatory standard. Inevitably, the whole mapping procedure involves various types and levels of uncertainties and one may ask how reliable is the delineation of the areas and shapes of the zones identified as polluted. It is the purpose of this paper to discuss some of the main sources of uncertainties that are attached to radiological risk maps by means of a case study as well as how these uncertainties may affect the overall decision process.JRC.H.4 - Transport and air qualit
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
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
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