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- Volume 8, Issue 5, 2010
Near Surface Geophysics - Volume 8, Issue 5, 2010
Volume 8, Issue 5, 2010
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Combined holographic subsurface radar and infrared thermography for diagnosis of the conditions of historical structures and artworks
Authors L. Capineri, P. Falorni, S. Ivashov, A. Zhuravlev, I. Vasiliev, V. Razevig, T. Bechtel and G. StankiewiczABSTRACTThis paper describes a new application of holographic radar for non‐destructive testing applied to cultural heritage items. A holographic radar, called RASCAN, operates in continuous wave multi‐frequency mode at 4 GHz range and produces images with high in‐plane resolution (about 2 cm). Marble items and other stones have been investigated to validate the method to search for subtle cracks, moisture or to unveil details of structures at shallow depth (up to 2 wavelengths). Other important materials are aged wood items that are investigated for tunnels made by insects. Then the holographic radar imaging has been experimentally compared with infrared thermography to understand the advantages and disadvantages of these methods and to derive indications for solving the problem common in all geophysics of inherent non‐uniqueness.
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Use of a sub‐array statistical approach for the detection of a buried object
Authors Simone Meschino, Lara Pajewski and Giuseppe SchettiniABSTRACTA hybrid electromagnetic‐statistic approach for the detection and localization of a perfectly‐conducting circular cylinder, buried in a lossless half‐space, is presented. We use the results of a cylindrical wave approach forward solver as input data for our detection procedure. We use a sub‐array processing structure and apply several algorithms for the direction of arrival estimation. By triangulating the found directions of arrival, a set of crossings, condensed around the object locations, is obtained. To process the crossing pattern, we developed a statistical model for the crossings distribution and employed hypothesis testing procedures to identify a collection of small windows containing the target. By defining a suitable threshold from a desired false alarm rate and dividing the region in small windows it is possible to ascribe each window to the ground or to the object. Numerical results are presented for a cylinder in a vacuum and in a dielectric half‐space, both in a central and in a peripheral position with respect to the array centre. Different values of the cylinder radius and of the distance from the array are considered.
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Ground‐penetrating radar and microwave tomography to evaluate the crack and joint geometry in historical buildings: some examples from Chania, Crete, Greece
Authors M. Bavusi, F. Soldovieri, S. Piscitelli, A. Loperte, F. Vallianatos and P. SoupiosABSTRACTDiagnostics of historical buildings is crucial for the definition of a reliable restoration project or in the study of the seismic behaviour of a building. This was one of the objectives of the international project ‘Advanced techniques for Seismic RISK Reduction in Mediterranean Archipelago Regions’ (SE RISK). In particular, in the framework of the project, the present work is concerned with the exploitation of GPR for the inspection of two historical buildings of Crete Island, Greece, the Prefecture of Chania and Venizelo’s House. In particular, the surveys aim at gaining information about the structure of the floors fracture areas and structural joint zones via high‐resolution measurements thanks to the use of a 1500 MHz nominal centre frequency antenna. With regard to the Prefecture of Chania, the specific aim of the survey was to detect and localize fracture areas and joint zones thanks to a scanning line acquired orthogonally to the ‘defects visible’ at the surface of the floors. In Venizelo’s House, the aim was to detect and localize fracture areas in the stone masonry.
Besides the classical time data processing, a microwave tomography based approach was applied to the data. The comparison between the two approaches has shown that the results of both the procedures are in good agreement suggesting both the reliability of the standard processing routine and the new microwave approach. In addition, the microwave tomographic approach provides more detailed and higher resolution images allowing an easier data interpretation. The microwave tomographic approach also offers the advantage of performing an automatic procedure, thus mitigating the risk of introducing subjective elements as in the case of the classical approach.
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A feasibility study of a quantitative microwave tomography technique for structural monitoring
Authors I. Catapano, L. Crocco and T. IserniaABSTRACTQuantitative microwave tomography is an imaging method based on the solution of a non‐linear inverse scattering problem, which is able to provide an objective assessment of a region under test. Such a capability is relevant in the framework of non‐destructive structural monitoring, where it allows to process ground‐penetrating radar data so to achieve accurate information on the inner status of the probed structure. In this paper, we propose a two‐step quantitative microwave tomography approach in which the morphological characterization of the targets is first pursued and then their electric contrast is determined by exploiting the information previously gained. A feasibility assessment of the proposed strategy is given against synthetic data concerning the imaging of a leaking pipeline embedded in a wall.
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Definition of buried archaeological remains with a new 3D visualization technique of a ground‐penetrating radar data set in Temple Augustus in Ankara, Turkey
More LessABSTRACTThe aim of this paper is to image particularly buried archaeological remains with a new technique for 3D display in the Temple of Augustus (Monumentum Ancyranum) relating to the Roman time, around and in Agora in the Ulus district of Ankara, Turkey. 2D ground‐penetrating radar (GPR) data were acquired on constant spaced parallel profiles in the study area. After data processing, a 3D data volume was built using a parallel 2D data set. The full data block was divided into sub‐data blocks in time. A weak amplitude range was made invisible with zero opaque by applying zero opacity to these values in the visualization. The arranged visible maximum amplitude range was enlarged or the amplitude scale was weighted with a constant coefficient, which was greater than one and smaller than two and had a decimal number, according to the time range. In this way, a transparent 3D image was obtained for determining buried remains according to the depth range. Interactive visualization was carried out by constructing sub‐blocks of the transparent 3D volume.
The interactive transparent 3D visualization was provided to identify the archaeological remains on native locations with depth in a 3D volume. Very complex and deep wall structures were visualized with any depth range inside (cella) of the Temple of Augustus and a few very narrow cubic anomalies exceeding 4 m deep were determined at the East side of the temple. An excavation could not be carried out in the cella because of the sensitivity problem of the cella walls. However, excavations in front of the East wall of the temple encouraged the new 3D image results. In addition, a lot of iron clamps connecting wall marble stones were determined on a profile gathered on the East wall.
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GPR application to the structural control of historical buildings: two case studies in Rome, Italy
Authors P.M. Barone, A. Di Matteo, F. Graziano, E. Mattei and E. PettinelliABSTRACTPreservation of historical buildings requires particular care, as any intervention must not alter or damage the style, structure or contents of the edifice. In order to properly plan the restoration of a building, non‐destructive techniques can be used extensively to detect structural elements and weaknesses. Ground‐penetrating radar (GPR) is particularly well adapted to this type of work, as the method is non‐invasive, rapid and provides high‐resolution images of contrasting subsurface materials.
In the present work we show the successful application of the GPR technique to the investigation of two historical buildings that differ in age, structure and geometry.
The first case is the GPR detection of fractures and internal lesions in the architrave of the Porticus Octaviae, a partially restored Roman building. The second case uses GPR in the important Zuccari Palace to determine the internal structure above vaulted ceilings that host a series of 16th century frescos. Both buildings are located in downtown Rome, Italy.
These examples show that GPR can give detailed, non‐invasive data that describe the state of conservation of historical buildings. In particular, this technique can produce fundamental information for the restorers (e.g., location, dimension and geometry of the structural lesions) that will help them develop the best possible protection plan, retrieving quantitative information about the location and the dimension of the lesions as well as the thickness of the different layers.
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The use of ground‐penetrating radar to extend the results of archaeological excavation
By Erica UtsiABSTRACTThis paper describes the use of ground‐penetrating radar (GPR) to extrapolate from data generated by a long‐term training excavation in Gloucestershire, SW England for which geophysical survey techniques including GPR had been used. Due to external circumstances beyond the control of the archaeological team, the ownership of the site changed hands and all excavation and associated investigation had to cease. However, an adjacent landowner granted permission for a GPR survey across his land. These latest GPR survey results have been used to supplement the excavation results, significantly extending the information available to the archaeological team. The data demonstrate the accuracy with which GPR data can be matched to excavation data and the improvement in target definition possible with reduction of transect spacing. The impact of some of this information is still being evaluated.
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Integrated techniques for analysis and monitoring of historical monuments: the case of San Giovanni al Sepolcro in Brindisi, southern Italy
ABSTRACTIn this paper, an integrated prospecting performed in the atypical Romanesque church of San Giovanni al Sepolcro in Brindisi, southern Italy is presented. Ground‐penetrating radar (GPR) and ultrasonic data have been gathered on the circular load‐bearing colonnade of the monument. Here the results achieved on two of the columns are shown. The GPR data have been processed and have allowed to identify and focus the medieval internal metallic hinges joining the stone trunks in one of the columns and some reinforcement rebars in the other (and probably also the residual track of a restored fracture). The ultrasonic data have allowed to monitor the state of compactness and to assess the effectiveness of reinforcement interventions on the columns.
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Archaeo‐geophysical methods in the Templo del Escalonado, Cahuachi, Nasca (Peru)
Authors Enzo Rizzo, Nicola Masini, Rosa Lasaponara and Giuseppe OreficiABSTRACTThe application of geophysical prospection methods to detect earthen remains is one of the major challenging issues to be addressed in archaeological investigations. The subtle geophysical contrast between earthen buried remains and the surroundings makes the detection of archaeological features very difficult. In this paper, we address this challenge using a multi‐technique approach. The integration of different geophysical methods has been used to identify archaeological remains in Cahuach, Peru, which is the largest adobe ceremonial centre in the world. The investigations herein presented are focused on two different geophysical campaigns carried out in 2008 in an area of the Templo del Escalonado, which is highly representative of the whole archaeological site. It is a desert environment where the archaeological features are covered by sand and alluvial material.
The geophysical prospection, required by the archaeologists to guide excavation planning, was performed using both ground‐penetrating radar (GPR) and geomagnetics with a gradiometer system. The first allowed the detection of significant anomalies, the latter confirmed the presence of these anomalies and also provided additional features not visible from GPR.
Trial excavations were carried out in correspondence of some anomalies. The archaeologists unearthed a ceremonial offering in correspondence of an anomaly detected using both GPR and geomagnetic methods. Moreover, an altar and precious archaeological materials were discovered in the area characterized by a magnetic anomaly. From an archaeological perspective, these findings were very significant, because they enabled us to cast new light on the Templo del Escalonado.
From a geophysical perspective, our results pointed out the high potentiality of magnetic and GPR techniques to detect, investigate and document adobe archaeological remains in a desert environmental setting.
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Volumes & issues
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Volume 22 (2024)
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Volume 21 (2023)
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Volume 20 (2022)
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Volume 19 (2021)
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Volume 18 (2020)
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Volume 17 (2019)
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Volume 16 (2018)
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Volume 15 (2017)
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Volume 14 (2015 - 2016)
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Volume 13 (2015)
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Volume 12 (2013 - 2014)
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Volume 11 (2013)
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Volume 10 (2012)
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Volume 9 (2011)
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Volume 8 (2010)
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Volume 7 (2009)
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Volume 6 (2008)
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Volume 5 (2007)
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Volume 4 (2006)
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Volume 3 (2005)
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Volume 2 (2004)
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Volume 1 (2003)