1,720,981 research outputs found
Formation of Platinum-Enamine Complexes by Reaction of Zeise's Salt with Secondary Amines
No full textNumerical analysis of the hydraulic transient in a closed pipe in presence of a bypass valve
No full textHydraulic transients generated when sudden changes in flow rates occur in a pressurized pipeline system were and are still today a crucial technical aspect of their operation. This is a common concern of hydraulic engineers aiming to reduce pressure waves in order to limit their related effects onto the hydraulic system components. From this perspective, the presence of a bypass system is recognized as useful to reduce the maximum water hammer overpressure during a pipeline closure; however, the sizing of bypass system is usually heuristic. This paper investigates the sizing procedure for a bypass system (i.e. pipe and valve) mainly considering the overpressure reduction values as dependent on some typical parameters for such pipe systems. A numerical model is used to investigate the efficiency of a bypass system in reducing the maximum water hammer overpressure, showing that an optimally designed bypass system allows to completely close a pipe in a lower time simultaneously saving the integrity of existing devices. Results show that the optimal diameters for a bypass valve is comprised in the range of 20%–40% of the main pipe diameter. In this way, a bypass system allows an overpressure reduction higher than 70%, which is important for faster manoeuvres
Application of short time series analysis for the hydrodynamic characterization of a coastal karst aquifer: the Salento aquifer (Southern Italy)
No full textDaily precipitation and groundwater level data, registered at 7 rain gauge stations and 11 monitoring wells in the Salento coastal karst aquifer (Southern Italy) were subject to short time series analyses to evaluate the hydrodynamic response of the aquifer. Results show that the Salento karst system has in general great storage capacity, which suggests a poor degree of aquifer karstification, and dominance in the permeability structure of not well-developed hierarchical karst networks. Baseflow generally dominates on quick flow, which only occasionally occurs. The dominant hydraulic behaviour is unimodal baseflow with a bimodal baseflow and quick flow one from time to time. Some local specific features, which emerge depending on the rainfall frequency and depth, and the geological and structural characteristics, point out that some components of the permeability structure, as the epikarst and major faults, only activate depending on the characteristics of the input. The study is novel because the analyses concerned specific sets of hydrological years from 2007 to 2011; also, because the analysis was conducted for a coastal karst aquifer of significant size, characterized by a regional groundwater flow system with an unsteady lower boundary, without inland freshwater springs, and significant exploitation by wells
I processi di erosione nel bacino della Diga di Abate Alonia: analisi fenomenologica e modelli di previsione
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Valutazione della potenziale erodibilitá di un bacino a differenti scale di applicazione
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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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