1,720,986 research outputs found
Evaluation of the Stability of UndergroundRock Pillars through a Probabilistic Approach
No full textProblem statement: When the room and pillar mining method is adopted, the dimensioning of the rock pillars is one of the most important aspects that need to be faced from the engineering point of view. The available calculation methods are usually simplified and involve the areas of influence method for the evaluation of the mean axial stress induced in the pillar and the empirical formula to estimate the global strength of the pillar. Approach: A new probabilistic approach is proposed in this study concerning the evaluation of the degree of safety of a pillar, as far as rupture of the rock is concerned. This approach is based on the exact evaluation of the stress state inside the pillar and it takes into due consideration the typical uncertainty of the geomechanical parameters of the rock mass that makes up the pillar. Results and Conclusion: The pillar can therefore be dimensioned through an analysis of the cumulative probability distribution of the point safety factor in one or more points inside i
Analisi dell’incidentalità ferroviaria. Aspetti metodologici e pratica attuativa
No full textLa caratterizzazione dell’incidentalità ferroviaria con indicatori quantitativi è una necessità imperativa quando si deve procedere all’analisi di rischio. E’ il caso delle gallerie ferroviarie per le quali il D.M. 28/10/2008 prevede l’uso dell’Analisi di Rischio Quantitativa per verificare il raggiungimento di un prefissato livello di sicurezza.
Con particolare riferimento a tale Decreto si propone una procedura di stima di tassi e ratei di incidentalità propedeutici al calcolo delle probabilità degli eventi iniziatori attraverso:
- lo studio delle serie storiche degli eventi incidentali e dei guasti predittivi degli stessi per determinare i tassi generici di rete degli eventi iniziatori per categoria rotabile;
- l’analisi degli alberi delle cause per definire le modalità realizzative degli eventi incidentali di collisione, deragliamento e incendio in armonia con il livello di dettaglio delle raccolte incidentali;
- la stima delle caratteristiche della linea (modalità di gestione del traffico e aspetti infrastrutturali) sui tassi generici di rete
L’Analisi di Rischio nelle gallerie ferroviarie. Basi etiche e sociali dei criteri di accettabilità
No full textThe expectation of a higher level of safety in clearly declared in the Italian acts for rail cases where are indicated the quantitative values to be achieved as well as criteria and procedure for demonstrating the above results.
The risk-based approach in the context of safety management offers the opportunity to get a transparent and consistent approach to decision-making about risks.
Here below are defined the Risk Indicators to be used in Italy, according the government act (2005) on “Safety in rail tunnels”.
Individual Risk Indicators IR = Individual Risk (Probability to be “victim” in a “fatal” accident occurred in a specific tunnel in a year) IR(x) = Point Individual Risk (Probability to be “victim” in a “fatal” accident occurred in a specific point x of a tunnel in a year).
Societal Risk BCR = Back Cumulated Risk Distribution so called FN curve (Probability P(N≥Nt) /Year-Tunnel
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
Flood hazard: planning approach to risk mitigation
No full textControl of risks associated with floods in recent years has a central role in urban planning scientific research. This is related to the increased incidence of these phenomena whose the root cause was found in the greater frequency of extreme rainfall events as a result of climate change. In Italy the phenomenon became dramatic because of the numerous human casualties that occur each year.
Without prejudice to the need for interventions that effectively act on climate change, there is a need to provide interventions to mitigate the consequences in the short-term. The Department of Urban Planning at Naples University has conducted a thorough research on the case, objectively verifying the impact that human activity has on the dramatic consequences of rainfall events, also highlighting the lack of efficiency of the traditional mitigation measures based on the construction of huge detention basins dug in the ground. This is due to three main reasons: such interventions require financial investments that local communities often do not have; the creation of detention basins cause the removal of large quantities of soil for agricultural use; the continuous increase in impervious surfaces due to urbanization implies the need to cope with the masses of water ever more impressive and therefore the dry ponds already created quickly become insufficient. The research proposes some interventions and best practices that, if adopted, can radically reduce the impact of extreme rainfall on public safety, enabling an efficient participation of private capital in investments through the use of leverage financial and fiscal incentives
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