1,721,020 research outputs found
Analysis of the foam penetration in the EPB excavation
Full text linkNowadays, the problem of reduction of environmental impact about construction of underground buildings is one of the main issue discussed during design phase. Foams, essential for EPB, consist of biodegradables surfactants which are injected in pressure ahead the cutterhead, inside the excavating chamber and along the screw conveyor. The present work aims to understand the process of foam diffusion through saturated media by using a new experimental procedure
Elastic properties of two-component grouts at short curing times: The role of bentonite
Full text linkTwo-component grout is nowadays the material most used for the backfilling phase in tunnelling with a shield machine. The operative simplicity of the technology and the fast hardening reaction between the two components are the main reasons that have contributed to the intensive spread of the use of this backfilling technique all around the world. Although bentonite is one of the basic ingredients for the grout production, its effect on the elastic properties of the grout has not been completely investigated so far. In this work, six different two-component grouts and their elastic properties have been studied by means of geophysical measurements. The six grouts were characterised by the same mix design and five different bentonites, while one grout had no bentonite. The variation of the dynamic parameters over time was analysed at short curing times (up to 24 h). In detail, the shear wave velocity, the dynamic moduli and Poisson's ratio were determined by means of the ultrasonic pulse velocity technique. The results show that the grouts with the bentonites have higher dynamic moduli than the grout without the bentonite. Moreover, a final analysis of the experimental data provided an analytical relationship to calculate the shear-wave velocity for each of the six grouts at any curing times
Ecology of the bivalve-inhabiting hydroid Eugymnanthea inquilina (Cnidaria, Hydrozoa, Leptomedusae, Eirenidae) in the coastal sounds of Taranto (Ionian Sea).
No full textThe life history of the bivalve-inhabiting hydroid Eugymnanthea inquilina was investigated in two different hosts, the mussel Mytilus galloprovincialis (collected from 1989–1991 from the Ionian Sea, Italy) and the clam Ruditapes decussatus (collected from 1991–1992, Ionian Sea, Italy). Hydroids living in mussels revealed a size selection for hosts longer than 40 mm, being almost completely absent in mussels below this size. This might be controlled by signals linked to the sexual maturity of the bivalve. The proportion of molluscs inhabited showed a seasonal trend in mussels only, with a sharp decline at the onset of medusoid liberation. Production of medusoids was high in mussels, whereas medusoids were rare and often abortive in clams. This indicates a higher degree of fitness of E. inquilina in mussels than in clams. The hydroid life cycle was not completed in clams, which therefore were presumably supplied by planulae from medusoids produced by mussel-inhabiting hydroids. Mussels played a key role in the stability and persistence of E. inquilina populations in the studied area. Selective ingestion of trematode sporocysts by E. inquilina hydroids indicated a protective role of the hydroid against mussel parasites, leading to reconsideration of this symbiotic association as a possible mutualism rather than a simple inquilinism
Bentonite in two-component grout applications
Full text linkTwo-component grout is a cement-based material, currently the most used technology for backfilling in tunnelling applications. Despite its intensive, knowledge on this material is quite limited, especially as concern the role of ingredients and their effect on the properties of fresh mortar and hardened grout. In this work, an accurate and innovative test campaign focused on the role of the bentonite was performed. Three different bentonites were used. The activation of the bentonite and its effect on both mortar stability and grout strength was investigated with the purpose to recognise the bentonite parameters useful to select, at the design stage, the best bentonite according to the designers’ requirements. Swell index and Atterberg's liquid limit were recognised as useful parameters for predicting results in terms of suitable bleeding and surface compression strength
Italian guidelines for the risk classification, safety evaluation and monitoring of existing tunnels: An overview
Full text linkThe Italian transport network had a great expansion after World War II and a great number of
tunnels were built. After 70 years, those tunnels are approaching their design lifetime. With more than 9000
tunnels extended for 2600 km of underground structures on the Italian national territory, the correct manage-
ment of this asset is challenging, especially in the context of a complex road network.
To provide an integrated method to monitor and plan the maintenance actions for the different stakeholders
on a national scale, a Guideline for the risk classification, safety evaluation and monitoring of existing tunnels
has been implemented by the Italian Superior Council of Public Works and is now mandatory for roadways
tunnels in Italy.The guidelines are structured in 5 levels with progressively increasing levels of knowledge
requirements and detail of the investigation, where level 0 is dedicated to a census of all the available infor-
mation about the tunnel, level 1 is dedicated to the inspections that have to be carried out with the help
a specifically designed defect catalogue. Then, accordingly to the data collected, in level 2 a classification to
prioritize further investigations, standard maintenance procedures, or ad hoc designs is regulated through
a series of logical operators to ensure that the same classification procedure is used for all the tunnels in the
national territory. This last level is subdivided into 6 fields with regard to specific critical phenomena that
may lead to a risk to the proper functioning of the tunnel. Then, levels 3 and 4 are respectively dedicated to
preliminary and accurate safety evaluations, while the last level regulates the maintenance of tunnels of stra-
tegic interest for the nation.
In this paper, a detailed discussion of the structure of the guidelines and about their application is
presented
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
I DIPINTI MURALI STACCATI: CRITICITÀ E NUOVE PROPOSTE
No full textLa tesi di Laurea Magistrale a ciclo unico, in "Conservazione e Restauro dei Beni Culturali", della Dottoressa Nicoletta Chiparo, riguarda l'intervento di restauro di un lacerto di dipinto murale staccato, di età paleocristiana, raffigurante un'orante; l’approccio alle problematiche di conservazione del dipinto murale ha suggerito l’avvio di una ricerca bibliografica e di laboratorio sui materiali per la realizzazione degli strati di sacrificio per i dipinti murali staccati.
Il dipinto murale, di provenienza incerta e delle dimensioni di cm. 60 di h, cm. 41.5 di larg. mm. 1-3 di sp., rappresenta una figura femminile orante che, per la resa del volto, dei particolari dell’acconciatura e la cura nell’abbigliamento sembra rientrare in un filone ritrattistico che inizia con l’Orante del cubicolo della “Velata” nella catacomba di Priscilla a Roma, della metà del III secolo, e di cui fa parte anche Dionysas nel cubicolo dei cinque santi nella catacomba di San Callisto a Roma, collocabile tra la fine del III e l’inizio del IV secolo d. C.
Il lacerto di dipinto ha subito vari interventi nel corso del tempo: l’ultimo dei quali riferibile agli anni ’70, ha previsto il collocamento del dipinto su un supporto autonomo (H 64,5 cm, L 44,2 cm, S 3 cm) costituito da un telaio ligneo, al quale è stata fissata la tela di sostegno, e la stuccatura perimetrale con malta a base di gesso, massicciamente rilevata lungo i margini frammentati del lacerto, che, prima dell’attuale intervento di restauro, occultava parte della superficie pittorica falsandone così la dimensione originaria. Sulla superficie pittorica era, inoltre, riscontrabile una stesura omogenea verde-grigiastra a base acquosa, che altera la percezione dei colori e appiattisce la superficie.
L’intervento di restauro è stato eseguito con lo scopo di migliorare le condizioni conservative dell’opera e la lettura unitaria del dipinto, rispettando l'identità della materia originaria, purtroppo compromessa da interventi precedenti. Al fine di approfondire lo studio dello stato di conservazione del reperto e di adottare una corretta metodologia d’intervento, sono state condotte indagini multispettrali, quali la fuorescenza ultravioletta (UVFLU) per evidenziare le ridipinture, l’analisi in Falso Colore che ha evidenziato un’alta concentrazione di stuccature in gesso. Dalla fluorescenza ultravioletta si è inoltre evidenziata la presenza di una sostanza organica, probabilmente dovuta alla colla utilizzata per l’intervento di stacco e di un olio siccativo riconducibile ad un protettivo. La presenza di cera sulla superficie pittorica, di colla organica all’interno delle fratture e anche del caseinato di calcio, utilizzato quale adesivo per far aderire il backing di tela al retro del dipinto murale, è stata confermata dalle indagini spettroscopiche FT-IR e Raman. Nel corso dell'intervento di restauro è stato possibile recuperare la leggibilità e restituire piena dignità ad reperto archeologico e, inoltre, agendo con la massima attenzione durante le fase di pulitura, sono stati rivelati preziosi dettagli iconografici ormai scomparsi. A conclusione dell'intervento è stato adottato un nuovo supporto autonomo in Aerolam e durante la progettazione di esso è stata parallelamente avviata una sperimentazione sull’utilizzo di un nuovo materiale per la realizzazione di strati di intervento a base di sughero con diversi adesivi.
La sperimentazione, sebbene ancora preliminare, evidenzia buone potenzialità ed applicabilità per i dipinti murali staccati grazie all’elevata elasticità mostrata dal materiale utilizzato, che garantisce migliore adattamento alle tensioni della tela di sostegno a suo tempo utilizzata nello stacco, e dalle caratteristiche di durabilità del sughero e alla buona reversibilità garantita dalla corretta scelta dell’adesivo.The paper shows the results of the restoration of the fresco of the "Orante" of the Archaeological Museum "A. Salinas" of Palermo. Preliminary experimentation shows good potential and applicability for detached wall paintings thanks to the high elasticity shown by the material used, which guarantees better adaptation to the tensions and good reversibility guaranteed by the correct choice of adhesive
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