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Page 186 of 977 Results 1851 - 1860 of 9762

M. Faifer, S. Goidanich, C. Laurano, C. Petiti, S. Toscani, M. Zanoni
Measurement Setup for the Development of Pre-Corroded Sensors for Metal Artwork Monitoring

The monitoring of environmental corrosivity towards cultural heritage is key task for both active and preventive conservation. In case of metallic artworks, this task can be performed by means of coupons or sensors realized with the same materials of the artworks to be conserved. In this work, a measurement system for the development and testing of sensor for atmospheric corrosivity monitoring is presented. The metrological features of the measurement system are analyzed aimed to the optimal analysis of a developed corrosion sensor. A sensor is also proposed. It permits to consider also the effect of the presence of corrosion layers on the object to be preserved, in order to achieve a better evaluation of its actual corrosion rate as a function of environmental conditions.

Lins, S.A.B., Di Francia, E., Grassini, S., Gigante, G.E., Ridolfi, S.
MA-XRF measurement for corrosion assessment on bronze artefacts

In this study, an innovative portable macro X-Ray Fluorescence (MA-XRF) scanner prototype has been employed in order to gain information on composition and distribution of corrosion products artificially grown on Cu-based coupons. First results have shown the importance of using artificially corroded reference samples before any assessment on archaeological artefacts. Moreover, the prototype used demonstrated to be a powerful tool for understanding complex corrosion processes which might occur on Cubased alloys. The scanner was able to detect light elements as S and Cl, essential for studying the distribution of specific corrosion compounds. Using imaging techniques, it was possible to observe a gradient in Cu elemental maps intensity caused by the overlapping of a thicker corrosion product layer.

Tilde de Caro, Leila Es Sebar, Emma Angelini
Micro-Raman investigation of dangerous corrosion products of archaeological bronzes from Tharros (Sardinia-Italy)

A large number of bronze artefacts have been found during archaeological excavations carried out at Tharros (Sardinia, Italy). The composition of corrosion products have been determined by the combined use of optical microscopy (OM), micro- Raman spectroscopy (μ-Raman), scanning electron microscopy (SEM) coupled with energy dispersive spectrometry (EDS). In particular, we will use μ-Raman spectroscopy to identify the corrosion products of natural patinas. This technique is equivalent or sometimes more efficient than microscopic and diffraction techniques to identify archaeological corrosion products. It is able to discriminate between different polymorphs, has a high spatial resolution and assures a correlation between the colour and the mineralogical nature. Furthermore has the advantage of being a nondestructive technique, quality highly valued in the cultural heritage.

Veronica Pazzi, Lorenzo Ciani, Luca Cappuccini, Mattia Ceccatelli, Gabriele Patrizi, Giulia Guidi, Nicola Casagli, Marcantonio Catelani
ERT investigation of tumuli: does the errors in locating electrodes influence the resistivity?

Among the princely tumuli near Vetulonia (Tuscany, Italy) the one of Poggio Pepe has never thoroughly been investigated. A joint project among three different departments of the University of Florence, lead to a new investigation campaign on this tumulus. The main goals are to verify the conservation structures state and to identify the tomb ancient access by means of geophysical methods. Moreover, this project aims to evaluate the influence on the geophysical acquired data of the error in collecting the geographical coordinates of the surface acquisition points. Optimizing the input data, in fact, it is possible to improve the anomalies localization and therefore facilitate the design of the excavation survey and the management of the research funding. The first results allow to make some assumptions about the state of the structures buried and suggest that in case of consistent error in locating acquisition points the measurement accuracy is strongly influenced.

Anna M. Gueli, Stefania Pasquale, Giuseppe Politi, Giuseppe Stella, Carlo Trigona
Indirect Temperature Measurements for TL Signal Loss during Drilling

Sampling represents an important phase of the procedure to perform authenticity test by thermoluminescence. The test could be compromised if this step is not properly carried out. In particular, if the local heating of the area subjected to the sampling by drilling reaches high temperatures, the signal results underestimated. In order to evaluate the increasing temperature during the sample collection in authenticity test, in this paper we propose a procedure useful for temperature in situ measurements using an indirect method. This method allows estimating the temperature dissipated during the drilling of the samples as consequence of the drill rotation. The temperature variation is obtained through the evaluation of an output voltage measured across a known reference resistor, in presence of a current.

Z. Vangelatos, M. Delagrammatikas, O. Papadopoulou, P. Vassiliou
Computational modelling of the mechanical behaviour of the Pentelic Marble -Steel clamp system on the structures of the Athens Acropolis

Computational modelling is employed to investigate the mechanical behaviour and failure scenarios of the Marble block - Steel clamp ancient masonry system utilized on the Athens Acropolis monuments, under static loading and modal analysis. The input data for the model are acquired by laboratory testing results such as tensile strength measurements and metallography, as well as bibliographic sources from various scientific fields (i.e. materials properties, archaeometry, restoration, structural engineering and geology). The effects of corrosion to the mechanical behaviour of the clamps are examined for two types of steel (E = 50 and E= 200 GPa) and the mechanical behaviour of the clamp - marble block system is examined for three realistic scenarios: (a) a well preserved ancient clamp, embedded in cast lead metal, (b) a well preserved early 20th century restoration clamp, embedded in Portland cement mortar and (c) a heavily corroded clamp surrounded by corrosion products. The aim is to build up a methodology that will take into account different states of preservation of the original and/or the restoration materials. This methodology could evolve further and be used as input for scaling up to structural engineering modelling.

Javier Pinto, Carlos Sanz-Minguez, A. Carmelo Prieto
Presence and Applications of Bituminous Materials on the Ancient Vaccaei Culture: a Nondestructive Spectroscopic Study

Archaeological works in the necropolis associated to the Vaccaei city-state of Pintia (Valladolid, Spain) have revealed a particularity of this culture (S. IV-I BC). A large set of bituminous objects have been found in enclosed funerary sets well contextualized. This material was first identified shaping spheres related to the Vaccaei burial rituals, a characteristic without archaeological precedents in the Iberian Peninsula. However, recent findings demonstrate a wider use of bitumen in the Vaccaei culture, being employed in the sealing of graves, as well as to fabricate daily life utensils. Nevertheless, this apparently high availability of bitumen contrasts with the absence of known natural bitumen sources in the Vaccaei territory. This work studied these bituminous samples using spectroscopic techniques. Their dynamic vibrational features were identified to determine if they were related to their potential use or age, as well as obtained, or not, from a unique source.

Principe Claudia, Giordano Daniele, La Felice Sonia, Giovannetti Giulio, Devidze Marina
Measuring instruments and protocols in Archaeomagnetic dating: Magneto-stratigraphy in Archaeology and Volcanology

Information related to the evolution of geomagnetic field in space and time are recorded in the rocks and are the subject of archaeomagnetic studies. These studies allowed us to better understanding the geomagnetic field evolution as well as to improve our comprehension of several geological aspects of the historic evolution of the Earth and human history. Here, based on the description of the functioning principia and models of past and presently used magnetometers we provide, based on our past experience, some suggestions to improve accuracy of archaeomagnetic measurements on fired archaeological materials and volcanic products.

Michela Albano, Giacomo Fiocco, Claudia Invernizzi, Maurizio Licchelli, Marco Malagodi, Raffaella Marotti, Curzio Merlo, Tommaso Rovetta, Daniela Comelli
Cleaning of historical scientific instruments: first analytical studies

Over the recent decades, the identification of scientific instruments as cultural heritage has drawn attention to their preservation, and today a lack of knowledge about this topic is drastically evident. Varnishes used during the 18th century in Europe and applied as a protective layer on brass components were known as imitation of Chinese lacquer coming from the oriental tradition. These varnishes were well considered for aesthetic and mechanical properties at the time which the manufacturing reached its apogee, and today they still protect the surface of a great number of historical masterpieces. A non-invasive methodology is employed to characterize the varnish reproduced with a traditional recipe and to monitor the effect of three cleaning methods widely used within the restorers community.

Luisa Spairani
Measure by Measure they touched the heaven

The measure of distances is a recurring theme in astrophysics. The interpretation of the light coming from a luminous object in the sky can be very different depending on the distance of the object. Two stars or galaxies may have a different real brightness, although they may look similar. The correct measures came by women computers a century ago. Special mention to Williamina Fleming who supervised an observatory for 30 years working on the first system to classify stars by spectrum. Antonia Maury helped locate the first double star and developed her classification system. Henrietta Leavitt found a law to determine stellar distances. The most famous of the Harvard computers was Annie Jump Cannon. An expert in photography, she catalogued over 350,000 stars and expanded the classification system used today but was Henrietta Leavitt to leave an indelible mark.

Page 186 of 977 Results 1851 - 1860 of 9762