1,721,020 research outputs found
Fenomeni vibratori da traffico stradale in presenza di strati con granulato di gomma
No full textLe vibrazioni generate dal traffico su gomma e su rotaia, originate dall’interazione dinamica tra
ruota e superficie di rotolamento, costituiscono un problema diffuso in molte città per gli effetti che
a lungo termine possono avere sugli edifici e sulle persone. Il fenomeno, causato essenzialmente
dalle irregolarità macroscopiche della superficie di rotolamento, è particolarmente sentito in
vicinanza di edifici storici e monumentali, maggiormente sensibili a causa della loro vetustà e
delle ovvie difficoltà che s’incontrano nel programmare interventi di manutenzione radicale.
Nel presente articolo si riferisce dei risultati ottenuti nel corso di una ricerca condotta presso il
Dipartimento di Idraulica Trasporti e Strade dell’Università “La Sapienza” di Roma, mirata alla
definizione di sistemi di mitigazione innovativi che, posti tra la sorgente delle vibrazioni e i
recettori “sensibili”, comportino una riduzione del disturbo.
Un’ampia attività sperimentale ha permesso di valutare su un campo prova la riduzione dei livelli
di vibrazione ottenibile grazie all’interposizione, all’interno del pacchetto della sovrastruttura
stradale, di strati di conglomerato bituminoso in cui parte della frazione “litica” venga sostituita
con granulato di gomma proveniente dal riciclaggio dei pneumatici fuori uso
Traffic Vibration Damping With Innovative Materials: Development And Calibration Of a Simulation Model
No full textThe reduction of vibrations transmitted by transport infrastructures, without increasing too much the
construction cost, is going to be a very important issue to deal with. The most effective construction
techniques used up to now are based on very complex and expensive solutions (such as floating slabs) and
on the use of special and once again expensive materials (such as elastomeric mats). One of the possible
innovative techniques is based on the use of hot mix asphalt in which a share of the traditional aggregates is
substituted with rubber granulate (2 – 4 mm) produced using waste tyres. This material could be used as sub
ballast layer in railway constructions and as binder or base layer in road construction. “Modified” hot mix
asphalt results in lower elastic modulus and higher loss factor compared with the traditional one, it can be
produced with the same machines and procedures resulting in comparable costs, as a consequence it can
be regarded as a very promising material to be used in the traffic vibration control field.
The prediction of the effectiveness of vibration damping systems is very complex due to the number of
variables involved and to the complexity of their relationships. Simulation and thence the possibility of a low
cost “try and error” approach becomes in this context an obvious answer to the problem, but once again the
complexity of the systems, the peculiar dynamic behaviour of involved materials makes reliable models hard
to be defined and calibrated.
The proposed approach is based on the calibration of the materials behavioural models comparing real and
simulated results of manageable and repeatable experiments (such as the complex modulus test or tests on
multilayer systems). The large amount of experimental data collected and evaluated allows first assessment
on the best material composition (share of aggregate substituted with rubber granulated first of all), and on
the more promising geometrical configurations, and leads to the definition of a reliable model suitable to be
used to individuate best solutions
Design and monitoring of a safe pedestrian crossing facility: via Venezia Giulia, Rome
No full textNearly all the travels have their “on foot” part; walking is therefore part of the everyday life of everyone and
must regarded as the most important mean of transport. Nearly all the “on foot” movements are “interrupted”
by crossings of car streets; crossing points are by far the most dangerous and uncomfortable spots for
pedestrians and are therefore the crucial points of a well designed and functional pedestrian networks. The
design of good pedestrian facilities should be made according to pedestrians’ needs, it should enhance
actual and perceived safety levels.
Pedestrians’ accidents are fortunately relatively rare events, the location of intervention priority only on the
base of statistical data is therefore not a satisfying approach, rather more or less analytical “preventive”
method, suitable to evaluate the functional level of crossing facilities, should be used. Evaluation methods
should be based on simple and easy to be made measures, and should return objective and easy to be read
results. The method used in the via Venezia Giulia case study is focused on the characterization of vehicular
flow and of the “functional quality” of the crossing facility, which is based on quantification of pedestrians
behaviour and pedestrians/car drivers interaction; moreover short interviews with users have been made to
understand reactions to the novelty.
The designed crossing point is located in a peripheral zone of Rome and connect a school to a park; the
crossed street has one lane/direction, a rather wide section and is characterized by high vehicular speeds.
The adopted solution is characterized by the provision of a median refuge, to divide the crossing distance
into two parts so to allow pedestrians to interact with just one vehicular flow at time; the provision of the
island results in a change of alignment for cars that induce drivers to slow down. Observations have been
made before and right after the intervention and shows good results; observations made more than one year
after the construction of the facilities have been used to evaluate long term effects
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
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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