1,721,021 research outputs found
Effect-based activities on air pollution: what is the state of the natural and anthropogenic Italian ecosystems?
Full text linkNegli ultimi venti anni, un grande sforzo è stato effettuato nella comunità italiana di lavoro sull’impatto dell’inquinamento atmosferico su diversi ecosistemi, sia naturali sia antropici. Al fine di colmare il divario tra scienziati e decisori politici, la comunicazione tra il lavoro svolto nei vari sottogruppi è stato recentemente migliorato e la realizzazione di questo testo monografico è il primo risultato tangibile di questo sforzo. L’intento del testo è quello di raccogliere informazioni di monitoraggio e di modellistica per ottenere relazioni dose-risposta in grado di stimare l’impatto degli inquinanti dell’aria sui diversi ecosistemi. Il territorio italiano è costituito da diversi ecosistemi peculiari, dalla zona costiera alle foreste, alle città incluse nella lista UNESCO del patrimonio culturale. È quindi molto importante proteggere il nostro patrimonio ambientale e culturale dalle pressioni ambientali e dell’impronta antropica. La salute dei principali ecosistemi naturali italiani è migliorata, anche se esistono ancora superamenti dei carichi e livelli critici, dei limiti di qualità dell’aria e una gran parte della popolazione è ancora esposta a livelli di inquinamento particolarmente significativi. Inoltre, molte delle più recenti politiche per ridurre l’inquinamento atmosferico hanno come obiettivo finale proprio la riduzione degli impatti negativi sulla salute umana e sugli ecosistemi. Molte soluzioni sono disponibili e solo un approccio integrato può valutare i benefici di considerare congiuntamente cambiamento climatico e inquinamento atmosferico. Solo l’integrazione di strumenti diversi, dalle misure ai modelli, e il coordinamento tra diversi settori e gruppi scientifici può portare ad indentificare politiche ambientali efficaci
Assessment of damage to people and buildings as consequence of hydrogen pipeline accidents
Full text linkHydrogen is increasingly considered a valid alternative to traditional fuels, which are gradually being more and more depleted. It is defined as “the energy carrier of the future” and so, as such, it must be produced. Several hydrogen production technologies are widespread and they involve both traditional and innovative sources. After its production, the hydrogen must be made available for use and, so, it must be transported from the production site to the utilization site. One of the most common ways to transport considerable quantities of gaseous hydrogen is through pipelines.
Since hydrogen is considered a “no safe” fuel due to its physical properties, the consequences of an accidental release must be investigated, to preserve the safety of people and facilities located in the surrounding area of a possible accidental event involving pipelines.
Hydrogen disperses into the air very easily, being lighter than air, but if it is released in a confined space can result in an explosion. The hazards of the hydrogen-air mixture are related to the wide flammability range and the low minimum ignition energy. Furthermore, hydrogen burns with an invisible flame and so it is very difficult to suddenly identify the presence of danger.
Based on these considerations, it results that a failure of pipeline conveying gaseous hydrogen can pose severe risks.
The aim of this study is to evaluate damage to people and buildings involved in high-pressure hydrogen pipeline explosions and (jet) fires and, to this scope, a probabilistic risk assessment procedure is proposed.
The annual probability of damage to people and to buildings exposed to an extreme event is calculated as the product of the conditional probability of damage given by a fire or an explosion and the probability of occurrence of the fire/explosion as consequence of pipeline failure.
The consequences of hydrogen pipeline accidents are estimated through different tools: the SLAB integral model is used to define the gas dispersion, the TNO Multi-Energy Method to evaluate the overpressure and impulse generated from the explosions and Pressure-Impulse diagrams to evaluate damage to buildings. The flame length is calculated through the SLAB model by considering the length at which the hydrogen concentrations of 4% (lower limit flammability) is reached.The point source model is employed to estimate the radiative heat flux generated by jet fire with the radiant fraction calculated through the empirical correlation proposed by Molina et al. (2007).
Finally, the Probit equations are used to calculate damage to people, both in the case of an explosion and a jet fire. The characteristic quantities of the two accidental events investigated, overpressure and impulse in the case of the explosions and radiative heat flux in the case of jet fires, are considered as causative variables.
Reinforced concrete buildings and tuff stone masonry buildings are taken into consideration to estimate the effect of overpressure and impulse caused by an explosion.
Direct and indirect damage on the people are investigated to define the effects of consequence of explosions and jet fires.
The probabilistic procedure proposed can represent a useful tool in the design of a new hydrogen distribution network and in risks assessment for existing ones
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
Quantitative risk assessment on a hydrogen refuelling station
Full text linkThe Directive 2014/94/UE (DAFI, Alternative Fuel Initiative Directive) on the deployment of alternative fuels (i.e. hydrogen) infrastructures has been recently transposed into national law in Italy. Consequently, the technical regulation on fire prevention for H2fuelling stations has been updated, in order to consider the current maximum delivery pressure (700 bar) of gaseous hydrogen for road vehicles. This technical regulation establishes the prescriptive safety distance from a piece of equipment. In the case of a new station, an assessment of the frequency of the event and its potential consequences is necessary. This is to understand which risk can reasonably be mitigated by a safety distance or whether additional mitigation or prevention measures should be taken. This paper presents the quantitative risk assessment (QRA) study on a hydrogen station planned to be installed, study which aims at determining the safety distances. Such study utilizes the Sandia-developed QRA tool, Hydrogen Risk Analysis Model (HyRAM), to calculate risk values when developing risk-equivalent plans. HyRAM combines reduced order deterministic models that characterize hydrogen release and flame behavior with probabilistic risk models to quantify risk values. Thanks to HyRAM tool it is possible to estimate physical effects and consequences on people and structures and plants, related to risk scenarios, by means of a damage model library. Use of risk assessment may allow station owners and designers to flexibly define station-specific mitigations, with the purpose of achieving equal or better levels of safety with respect to prescriptive recommendation levels, as suggested by ISO19880-1 (2018)
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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