Showing papers by "Marco Parvis published in 2010"

In-Process Temperature Mapping System for Industrial Freeze Dryers

Abstract: This paper describes a low-invasive temperature mapping system specially designed for vacuum and nonaccessible environments, such as industrial freeze dryers. Thermal resistances tend to become quite hight in vacuum since convection is absent and even very small gaps have extremely conductive resistances. Temperature monitoring in the vacuum therefore requires sensors that do not inject power to minimize the self-heating and a special attention to the effect due to the involved thermal resistances. The proposed solution employs small autonomous measuring nodes that use a wireless connection to transmit the results and that are characterized to correct the thermal constant effect during temperature changes. The system has been designed for the monitoring of large freeze dryers, but its characteristics make it useful in many other vacuum conditions. The system is capable of monitoring the temperature of hundreds of points with an uncertainty of the order of a degree and with a cost per point of a few euros.

Silver artefacts: plasma deposition of SiOx protective layers and tarnishing evolution assessment

Abstract: Silver artifacts suffer tarnishing when exposed to a sulphur containg atmosphere. Plasma deposited SiOx thin films are proposed for the protection of silver artefacts, owing to their optical transp...

Plasma modified POF sensors for in situ environmental monitoring of museum indoor environments

Abstract: A cumulative sensor for in situ monitoring of H2S vapors in museum showcases based on plastic optical fiber (POF) has been developed. H2S is responsible for the tarnishing of silver artifacts, so monitoring their total exposure over time to sulfide rich atmospheres can help in choosing the correct display procedure and, consequently, lead to improvements in their conservation.

An imaging approach for a contactless monitoring of the conservation state of metallic works of art

Abstract: An easy-to-use and cheap diagnostic tool based on digital photography and 2D-FFT imaging processing is described that can be used to monitor the corrosion process occurring over time on the surface of metallic works of art in indoor and outdoor environments and to assess the stability of the materials employed for restoration. The proposed solution has the advantage of not requiring standard lighting and artifacts manipulation, that are not easily achievable in real applications. The imaging algorithm is capable of highlighting the changes in the surface uniformity due to the corrosion process and can be used to put in evidence the beginning of dangerous localized corrosion phenomena onto the metallic surface. Although this technique does not allow a quantitative measurement of the corrosion rate, it has proved to be an effective approach to assess the stability of protective coatings. The proposed processing has been tested in laboratory to asses the stability of SiO2—like protective coatings deposited by PECVD on a set of silver reference alloys submitted to a tarnishing test in the presence of H2S vapors.

A multidisciplinary approach for the conservation of a building of the seventeenth century

Abstract: A long-term multidisciplinary conservation study is actually in progress inside the Villa della Regina, a prestigious Savoy residence built in the seventeenth century and recently restored. The walls of some rooms of the Villa are decorated with precious tin–mercury mirrors, that are baked with a reflective coating constituted of a tin–mercury compound surrounded by liquid mercury. The reflective layer is very soft, thus any restoration is difficult to be performed and can lead to a complete destruction of the artifact. Amalgam corrosion is a very slow process and, although there is no way to prevent the oxidation of the reflective layer, the conservation state of the artifacts may be improved by keeping them in a controlled environment. For this reason, a monitoring system has been designed and installed that is based on a wireless network of extremely compact sensors, for temperature and relative humidity measurements. The sensors have been specifically designed to satisfy the requirements for use in cultural heritage field and the system allows one to automatically collect the data that can be analyzed with the final aim to establish a correlation between the environmental conditions and the conservation state of the artifacts. A restoration has been carried out by producing in situ an amalgam inlay on the corroded area to slow down the release of liquid mercury in order to avoid also possible unsafe conditions for staff and visitors. In addition, a sensor has been developed which is based on a prototypical plastic optical fiber for the detection of low concentration Hg vapors to ensure the safe conditions in the Villa rooms. The sensor is being tested in laboratory.

Compact RF sensors for monitoring thermo-physiological comfort of sportswear

Abstract: The development of new competitive sportswear requires the analysis and the optimization of many textile properties. In particular, the thermophysiological behavior related to the sportswear plays a crucial role, having a direct impact on the athlete's performance. A way to investigate thermophysiological comfort consists in the continuous monitoring of humidity and temperature of the air layer between the skin and the item of clothing. However, this analysis can not be carried out by means of classical instruments, which are usually too big and require the use of wires. For these reasons, the possibility of employing miniaturized smart buttons, as wireless wearable sensors, is investigated and discussed.

FFT-based imaging processing for cultural heritage monitoring

Abstract: Conservation of precious metallic works of art requires an in situ monitoring of the conditions of the objects and of the protecting coatings employed for their restoration. In this paper a simple diagnostic tool based on digital photography and 2D-FFT imaging processing is proposed that is used for monitoring the corrosion process occurring on metal surfaces. The proposed approach has been tested in laboratory on a set of silver reference samples which have been coated with SiO x thin films deposited via plasma and submitted to a tarnishing test. The obtained results show that the proposed technique permits to overcome most of the problems usually encountered when using conventional image processing based on amplitude and colors that require maintaining standard lighting and artifacts conditions, that are not easily achievable in museums. Although the proposed solution is not able to provide details about protective coating failure and the corrosion mechanism, its results can be correlated to the tarnishing susceptibility and, therefore, this technique can be use to assess the stability of the artifacts and to put in evidence the beginning of dangerous localized corrosion phenomena, that require immediate restoration.

Electrical tomography for the monitoring of water moisture in painted walls and ceilings

Abstract: Painted walls represent a great heritage of cultural and artistic value. Unfortunately, these works of art, especially the frescos, are constantly attacked by moisture and salt content in the wall plaster, thus, particular attention has to be paid on their conservation state. Nevertheless, there are no many instruments that permit to detect the wall state without causing damages to the paintings. For these reasons, a non-invasive measuring system, which is based on resistivity measurements, is proposed to investigate the moisture content in painted walls and ceilings. The method is able to provide information not only at the wall surface but also at few centimeters beneath the painting, thus allowing one to detect dangerous situations before the deteriorating effects take place. Despite the attention has been focused on the conservation of work of arts, the proposed system can be employed in many other fields including the building sector in general.

An optic solution for the measurement of gas diffusion in thin films

Abstract: Thin films are increasingly used both for the development of innovative gas sensors and for surface protection purposes due to availability of new surface treatments, such as those based on low pressure and atmospheric plasma processes. In many cases sequential treatments are required, where, after the initial deposition, the film is exposed to different chemical compounds that both react and diffuse inside the film, usually to enhance its properties. These reaction/diffusion processes depend on many parameters connected to the layer morphology and are, therefore, complex and difficult to preview. Several authors have studied the problem and have developed powerful mathematical models, whose validation, however, is difficult since making measurements during the transient process, especially for films with nanometric thickness, is not easy. In this paper, the authors investigate two optical solutions that can be applied to many practical cases to follow the diffusion process of gases in real time and thus tune and validate the models. The first solution is based on the well-known Surface Plasmon Resonance (SPR) phenomenon and allows precise evaluations to be obtained, but requires a lab-type setup. The other solution employs a Plastic Optical Fiber (POF) and exploits the evanescent field interaction to arrange a simple and cheap setup, that can be used also for in situ tests. Both approaches are applied to the study of the diffusion of sulfide vapors in silver with subsequent surface tarnishing, a topic that represents a practical case of relevant importance in the field of cultural heritage preservation.

Caratterizzazione di componenti per laser di potenza in fibra ottica

Abstract: CARATTERIZZAZIONE DI COMPONENTI PER LASER DI POTENZA IN FIBRA OTTICA / A. Braglia; A. Carullo; F. Ferraris; A. Neri; M. Olivero; R. Orta; M. Parvis; G. Perrone; D. Tosi; A. Vallan. (2010). ((Intervento presentato al convegno XXVII Congresso Nazionale Gruppo Misure Elettriche ed Elettroniche tenutosi a Gaeta nel 13-15 Settembre 2010. Original CARATTERIZZAZIONE DI COMPONENTI PER LASER DI POTENZA IN FIBRA OTTICA