1,720,957 research outputs found
DEVIN : a simulator of volcanic events considered in terms of a stochastic punctual process
No full textWithin the framework of the EU-project MULTIMO (Multi-disciplinary monitoring, modelling and forecasting of volcanic hazard), a software called DEVIN (Deducing Eruptions of Volcanoes In Near future) aiming at forecasting volcanic activity in the near future is currently under development. DEVIN is based on geostatistical concepts and allows the characterisation of the behaviour of time series recorded at active volcanoes. The functions of DEVIN used for the simulation of discrete and continuous variables are the following:
- Time behaviour analysis by variogram calculation.
- Time behaviour parametrisation by variogram modelling.
- Stochastic simulation for Monte Carlo forecasting and data reconstruction (i.e., gap filling).
- Kriging analysis for estimation of time components related to volcanic activity.
- Statistical analysis and visualisation of modelling results.
DEVIN is an open source software, running under Scilab, that applies specific routines written in C and Fortran in order to avoid time consuming computations. DEVIN is a tool which provides the possibility to model time behaviour as characterised from multi-parametric data sets. It, therefore, should reduce the uncertainty in forecasts of volcanic activity
Development of a forecasting approach using stochastic methods applied to the Soufrière Hills volcano
No full textWithin the framework of the EU-project MULTIMO (Multi-disciplinary monitoring, modelling and forecasting of volcanic hazard), a stochastic methodology aiming at forecasting volcanic activity in the near future is currently under development. This approach is based on geostatistical concepts and allows the characterisation of the behaviour for time series recorded at active volcanoes.
The following steps are considered for analysis and simulation of discrete and continuous variables taken from multi-parametric data sets:
(a) analysis and parameterisation of time behaviour by variogram calculation,
(b) stochastic simulation for Monte Carlo forecasting and
(c) kriging analysis for estimation of time components related to precursors of volcanic activity
Stochastic forecasting: precursor identification and scenario simulation using multivariate time series from Soufrière Hills volcano, Montserrat
No full textTime series recorded at active volcanoes are often incomplete and can consist of small data sets. Due to the complexity of volcanic processes and inherent uncertainty, a probabilistic framework is needed for forecasting. A stochastic approach, named DEVIN, was developed to perform forecasts of volcanic activity. DEVIN is a multivariate approach based on geostatistical concepts which enables: (1) detection and quantification of time correlation using variograms, (2) identification of precursors by parameter monitoring and (3) forecasting of specific volcanic events by Monte Carlo methods. The DEVIN approach was applied using seismic data monitored from the Soufrière Hills Volcano (Montserrat). Forecasts were produced for the onset of dome growth with the help of potential precursors identified by monitoring of variogram parameters. Using stochastic simulations of plausible eruptive scenarios, these forecasts were expressed in terms of probability of occurrence. They constitute valuable input data as required by probabilistic risk assessments
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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