1,721,051 research outputs found
Modelli mono-dimensionali per il calcolo delle concentrazioni nel tempo
No full textPer poter effettuare facilmente previsioni semplificate per l'impianto EVA , attualmente in fase di definizione, vengono proposti alcuni modelli mono-dimensionali per la valutazione delle concentrazioni nel tempo di sostanze immesse in un ambiente provvisto di un impianto di ventilazione. Viene presentata una applicazione su di un caso significativo per l'impianto EV A , allo scopo di verificare l'idoneità dei modelli proposti, attraverso il confronto dei loro risultati
STIMA DELLE CONCENTRAZIONI DELLE EMISSIONI GASSOSE E DI PARTICOLATO NEL TEMPO: MODELLO MONO-DIMENSIONALE
No full textVengono presentati le valutazioni, ottenute utilizzando un modello mono-dimensionale della concentrazione in aria delle principali sostanze emesse da un autobus all'interno della hall tecnologica dell'impianto EVA
Stress Analysis of Bulk Carrier Hatch Corners
No full textOne of the most frequent damage cause for bulk carrier ships is represented by high stress
concentrations occurring in deck plating close to hatch corners in way of coaming stay. In this
area many fractures are found during surveys which are generated mainly by three types of
problems:
• stress concentration in correspondence of deck large openings;
• bad design of stays;
• different thickness between transversal and external deck plates.
The typical approach followed by IACS classification societies consists in a wide range of
qualitative suggestion (transversal stiffening for transversal deck strip, elliptical hatch corner
etc.) and a very simple formula providing the extra thickness of the hatch corner compulsory
insert.
This solution seems to be inadequate to face this phenomenon and a better knowledge is
mandatory to understand which parameters are more influent on stress distribution and
concentration.
The purpose of the analysis herein presented is to identify most important parameters and to
study their influence, in order to develop a more sophisticate procedure to be used in
preliminary design stage.
The investigation has been developed starting from the analysis of five different bulk carriers,
selected on the basis of their geometric and structural properties, and modeled with FEM
software Leonardo hull 3D v. 2.4.1.
The analysis has been divided into two sub-problems:
• study of b/B ratio influence (hatch breadth versus ship breadth);
• study of lw/b ratio influence (cross deck length versus hatch breadt)..
Two different series of FEM models have been realized:
Global models of the hull extended to a portion of three cargo holds;
Simplified models with increasing refinement degree.
All global models have a relatively coarse mesh and are loaded with a wide number of
loading condition (homogeneous, heavy and light ballast, alternate ore) corresponding to
relevant RINA load cases in order to maximize the effects. For what simplified models are concerned four different types of models have been analysed:
a) The first model consists in a simple plate with a rectangular opening and two longitudinal
box structures simulating the wing tanks. All the parts of the model have a constant thickness.
b) A second series of models has then been created, similar to the first one, adding a coaming
around the hatch opening. As in the first case the thickness has been maintained constant.
c) The third series is similar to the first one but the thicknesses of the lateral deck strip and of
the cross deck have different values, according to the real case.
d) The fourth series is similar to the second one. Again deck plates have different thicknesses. For all the models the results have been processed to calculate stress concentration factors “k”
(defined as longitudinal stress close to hatch corner versus theoretical hull girder stress) for all
selected loading conditions.
From the “k” coefficients obtained for every model, a “stress concentration surface”, as a
function of b/B and w/b, has been drawn and expressed by a simplified formula
Analisi fluidodinamica bidimensionale dell' impianto EVA
No full textPer effettuare previsioni delle concentrazioni stazionarie da misurare nell' impianto EVA durante le prove, viene effettuata una analisi fluido-dinamica bi-dimensionale con il codice FLOTRAN di ANSYS, per le sostanze inquinanti immesse nel sistema dal veicolo in prova ed in particolare presenti nei punti ove sono previste le misure strumentali. I risultati del modello fluidodinamico permettono la valutazione dell' effetto di alcune caratteristiche dell' impianto stesso sulle misure da effettuare
Indagine conoscitiva sul rischio chimico in edilizia durante l'impiego di prodotti vernicianti.
No full text
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
- …
