1,721,031 research outputs found
Identifiability analysis for pressure sensors positioning
Full text linkThe identifiability analysis is investigated as sampling design method aimed to the leakage
detection in looped water distribution networks. The preliminary ranking of the candidate nodes for
the pressure sensors positioning is performed by running several hydraulic simulations and
calculating sensitivity functions. The reduced subset of nodes and their sensitivities are then used to
perform the identifiability analysis by calculating the collinearity index which provides the
maximum number of sensors and their location into the network. The index selects the nodes
according to their sensitivities to several leakages scenarios, simulated in EPANET by changing
the emitter coefficient of the leakages function both with a One-At-Time and Monte Carlo
approach. The collinearity index also identifies the subset of the pressure monitoring nodes with
the lowest correlation (redundancy) between the measurements. The method is applied to the
benchmark network Apulian
Optimal positioning of water quality sensors in water distribution networks: comparison of numerical and experimental results
Full text linkIn the water distribution networks, a deliberate or accidental contamination causes loss of water
quality; the implementation of a real-time sensor network is essential to promptly detect the event of
contamination. To achieve the optimum positioning of the probes, to reduce the cost of the
instrumentation and maintenance, and obtaining, at the same time, a reliable monitoring of the
system, optimization techniques are widely applied.
In the present study, a numerical optimisation approach was compared with the results of an
experimental campaign. The optimization problem is formulated in accordance with literature stateof-
the-art, using the genetic algorithm NSGA-II coupled with a hydraulic simulator. The results
were tested and verified using a looped laboratory distribution network, equipped with a real-time
monitoring water quality system, which allows to run contamination experiments in a controlled
environment
Relationship Between Extreme Rainfall and Surface Temperature in Sicily (Italy)
Full text linkThe study of the relationship between extreme rainfall events and surface temperature represents an important issue in hydrology and meteorology and it could be of capital importance for evaluating the effect of global warming on future precipitation. Various approaches have been tested across different parts of the world, and, in many cases, it has been observed an intensification of precipitation with increasing temperature consistently with the thermodynamic Clausius-Clapeyron relation (CC-rate of 6-7% °C-1), according to which a warmer atmosphere is capable of holding more moisture. Nevertheless, in different locations, the scaling rate between temperature and extreme precipitation has resulted significantly different with respect to the CC-rate, in some cases sensibly higher (super-CC) and in other relevantly lower (sub-CC). In this work, an analysis of the scaling relationship between sub-daily extreme rainfall events and surface temperature is carried out, using data from a large number of rain and temperature gauges across Sicily (Italy). Results highlight the relevant importance of some modeling choices and, particularly, of rainfall duration, for this type of analysis in semi-arid region. An overall sub-CC scaling rate has been detected for most part of the region
Preliminary GIS Elaborations to Apply Rapid Flood Spreading Models
No full textFlood risk analysis involves simulating many scenarios from which to draw statistical information about flood extent and depth. Rapid but still sufficiently accurate models enabling flooded areas to be delimited using a DEM have been introduced in the scientific literature. These models, called Rapid Flood Spreading Models (RFSMs), are based on highly simplifying hydraulic assumptions while make large use of GIS information and elaborations. Three different RFSMs are here applied to a test case, largely characterized by flat land. The results obtained are compared with those of a two-dimensional hydraulic model confirming the possibility of preliminarily elaborating topographic GIS data to easily gain geometric information on flooded areas through geospatial analysis
Meandering evolution and width variation, a physics-statistical based modeling approach
Full text linkMany models have been proposed to simulate and understand the long-term evolution of meandering rivers. These models analyze the hydraulics of the in-channel flow and the river bank movement (erosion – accretion) process in different ways, but some gap still remain, e.g. the stability of long-term simulations when width variations are accounted for. Here we proposed a physics-statistical based approach to simulate the river bank evolution, that erosion and deposition processes act independently, with a specific shear stress threshold for each of them. In addition, we link the width evolution with a parametric probability distribution (PPD) based on a mean characteristic channel width. We are thus able to obtaining stable long-term simulations with realistic and reasonable spatio-temporal distribution of the along channel width
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
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