scholarly journals High resolution 3-D modelling of cylinder shape bodies applied to ancient columns of a church

2020 ◽  
Vol 54 ◽  
pp. 119-127
Author(s):  
Giuseppe Casula ◽  
Francesco Cuccuru ◽  
Maria Giovanna Bianchi ◽  
Silvana Fais ◽  
Paola Ligas
Keyword(s):  
High Resolution ◽  
Laser Scanner ◽  
Construction Materials ◽  
Longitudinal Axis ◽  
Ultrasonic Waves ◽  
Diagnostic Methods ◽  
Diagnostic Process ◽  
Ultrasonic Tomography ◽  
Destructive Testing ◽  
Central Column

Abstract. The use of Non-Destructive Testing (NDT) applied to construction materials allows to highlight and characterize their features, especially in the case of old buildings. The multi-technique high resolution 3D modelling described here is aimed to investigate the conservation state of the central column of a colonnade in the ancient church of Saints Lorenzo and Pancratio, dating to about the second half of the thirteenth century and located in the old town of Cagliari (Italy). This column was considered of interest because its longitudinal axis deviates from its ideal position and it appears the most deteriorated. In this work we describe the integrated application of 3D diagnostic methods, i.e. Terrestrial Laser Scanner (TLS), close range photogrammetry (CRP) and ultrasonic tomography supported by petrographic investigations. They were used to improve the diagnostic process of the conservation state of the investigated column. The TLS technique was supported by CRP to obtain a natural colour texturized 3D model of the column. The geometrical anomaly maps derived from the data of the TLS-CRP survey show the presence of some anomalies worthy of attention. Starting from the 3D reconstruction with previous techniques we planned and implemented a 3D ultrasonic tomography. Ultrasonic tomography proved to be a successful tool in identifying internal defects, as well as the presence of voids and flaws within the materials through the analysis of the propagation of ultrasonic waves. The integration of the three non-invasive techniques supported by petrographical analyses demonstrates its potential in reducing ambiguities since each technique brings its clue to the overall diagnostic process.

High Resolution 3D modelling of Cylinder shape bodies applied to 1000 ancient BC columns

2020 ◽  
Author(s):  
Giuseppe Casula ◽  
Silvana Fais ◽  
Francesco Cuccuru ◽  
Maria Giovanna Bianchi ◽  
Paola Ligas
Keyword(s):  
High Resolution ◽  
Building Materials ◽  
Laser Scanner ◽  
3D Modelling ◽  
Ultrasonic Tomography ◽  
Terrestrial Laser Scanner ◽  
Non Destructive Testing ◽  
Historical Buildings ◽  
Destructive Testing ◽  
Non Destructive

<p>A multi-technique high resolution 3D modelling is described here aimed at the investigation of the state of conservation of carbonate columns of the 1000 BC ancient church of Buon Camino located in the homonymous district of the town of Cagliari (Italy).</p><p>The integrated application of different Non-Destructive Testing (NDT) diagnostic methods is of paramount importance to locate damaged parts of the building material of artefacts of historical buildings and to plan their restoration.</p><p>In this study a multi-step procedure was applied starting with a high resolution 3D modelling performed with the aid of Structure from Motion (SfM) Photogrammetry and Terrestrial Laser Scanner (TLS) methodologies. For this delicate task we operated simultaneously a Nikon D-5300 digital Reflex 24.2 Mega pixel Camera and a Leica HDS-6200 Terrestrial Laser Scanner. Subsequently, starting from the information detected with the above methods deeper material diagnostics was performed by means of high resolution 3D ultrasonic tomography aimed at the capillary definition of the elastic properties in the inner parts of the building materials. Measurements of longitudinal wave velocity from ultrasonic data were performed using the transmission method, namely two piezoelectric transducers coupled on the opposite sides of the investigated columns. The ultrasonic data acquisition was planned designing an optimal survey and providing a very good spatial coverage of the investigated columns. The columns were then criss-crossed by a large number of ray paths forming a dense 3D net. The SIRT (Simultaneous Iterative Reconstruction Tomography) algorithm was used to produce the 3D rendering of the velocity distribution inside the investigated columns. With this method the damaged parts were located and it was possible to distinguish them from the unaltered areas. The information on the superficial material conditions obtained by SfM and TLS techniques were compared and integrated with the information of the inner materials obtained by 3D ultrasonic tomography.</p><p>The results of the above non invasive geophysical techniques have been interpreted in the light of the different textural and petrophysical features of the study carbonate building materials. The study of the main textural features, such as the relationship between bioclasts, carbonate matrix, or that of the cement and petrophysical characteristics such as the nature and distribution of porosity were found to be of fundamental importance in the interpretation of the geophysical data (e.g. TLS reflectance and longitudinal acoustic wave propagation). Therefore a detailed analysis of the textures and pore microstructure were carried out from petrographic thin-sections in Optical and Scanning Electron Microscopy (OM/SEM). The final result of our multi-step-technique integrated methodology is a sophisticated 3D model with a high resolution 3D image representing the internal and external parts of the investigated columns in order to account for their static load resistance and possibly plan their conservation and restoration. The described procedure can also be applied to other cases in which a diagnosis is needed of the state of conservation of the variously shaped, layered-stones and composed artefacts typical of ancient historical buildings.</p><p>Key words: 3D Modelling, 3D Ultrasonic Tomography, Terrestrial Laser Scanner, SfM Photogrammetry, Non-Destructive Testing, Diagnostic, Ancient Columns, Stones</p>

scholarly journals Characterization of Rock Samples by A High-Resolution Multi-Technique Non-Invasive Approach

Minerals ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 664 ◽  
Author(s):  
Silvana Fais ◽  
Francesco Cuccuru ◽  
Giuseppe Casula ◽  
Maria Giovanna Bianchi ◽  
Paola Ligas
Keyword(s):  
High Resolution ◽  
Laser Scanner ◽  
3D Models ◽  
Pyroclastic Rock ◽  
Ultrasonic Tomography ◽  
Invasive Approach ◽  
Rock Samples ◽  
Non Invasive ◽  
Two Samples ◽  
Invasive Techniques

Three different non-invasive techniques, namely Structure from Motion (SfM) photogrammetry, Terrestrial Laser Scanner (TLS) and ultrasonic tomography integrated with petrographic data, were applied to characterize two rock samples of a different nature: A pyroclastic rock and a carbonate rock. We started a computation of high-resolution 3D models of the two samples using the TLS technique supported by a digital SfM photogrammetry survey. The resulting radiometric information available, such as reflectivity maps, SfM photogrammetry textured models and patterns of geometrical residuals, were interpreted in order to detect and underline surface materials anomalies by a comparison of reflectance and natural colour anomalies. Starting from the 3D models from previous techniques, a 3D ultrasonic tomography on each rock sample was accurately planned and carried out in order to detect internal defects or sample heterogeneity. The integration of the above three geophysical non-invasive techniques with petrographical data—especially with the textural characteristics of such materials—represents a powerful method for the definition of the heterogeneity of the rocks at a different scale and for calibrating in situ measurements.

scholarly journals Decay detection in an ancient column with combined close-range photogrammetry (CRP) and ultrasonic tomography.

2021 ◽  
Author(s):  
Giuseppe Casula ◽  
Silvana Fais ◽  
Francesco Cuccuru ◽  
Maria Giovanna Bianchi ◽  
Paola Ligas ◽  
...  
Keyword(s):  
High Resolution ◽  
Diagnostic Process ◽  
Ultrasonic Tomography ◽  
Invasive Approach ◽  
Non Invasive ◽  
Close Range Photogrammetry ◽  
Close Range ◽  
Non Destructive ◽  
Non Destructive Techniques

<p>The diagnosis of the conservation state of monumental structures from constraints to the spatial distribution of their physical properties on shallow and inner materials represents one of the key objectives in the application of non-invasive techniques. <em>In situ</em>, CRP and 3D ultrasonic tomography can provide an effective coverage of stone materials in space and time. The intrinsic characteristics of the materials that make up a monumental structure and affect the two properties (i.e., reflectivity, longitudinal velocity) through the above methods substantially differ. Consequently, the content of their information is mainly complementary rather than redundant.</p><p>In this study we present the integrated application of different non-destructive techniques i.e., Close Range Photogrammetry (CRP), and low frequency (24 KHz) ultrasonic tomography complemented by petrographycal analysis based essentially on Optical Microscopy (OM). This integrated methodology has been applied to a Carrara marble column of the <em>Basilica of San Saturnino</em>, in Byzantine-Proto-Romanesque style, which is part of the Paleo Christian complex of the V-VI century. This complex also includes the adjacent Christian necropolis in the square of <em>San Cosimo</em> in the city of Cagliari, Sardinia, Italy. The column under study is made of bare material dating back probably to the first century A.D., it was subjected to various traumas due to disassembly and transport to the site, including damage caused by the close blast of a WWII fragmentation bomb.</p><p>High resolution 3D modelling of the studied artifact was computed starting from the integration of proximal sensing techniques such as CRP based on Structure from Motion (SfM), with which information about the geometrical anomalies and reflectivity of the investigated marble column surface was obtained. On the other hand, the inner parts of the studied body were successfully inspected in a non-invasive way by computing the velocity pattern of the ultrasonic signal through the investigated materials using 3D ultrasonic tomography. This technique gives information on the elastic properties of the material related with mechanical properties and a number of factors, such as presence of fractures, voids, and flaws. Extracting information on such factors from the elastic wave velocity using 3D tomography provides a non-invasive approach to analyse the property changes of the inner material of the ancient column. The integrated application of <em>in situ</em> CRP and ultrasonic techniques provides a full 3D high resolution model of the investigated artifact. This model enhanced by the knowledge of the petrographic characteristics of the materials, improves the diagnostic process and affords reliable information on the state of conservation of the materials used in the construction processes of the studied monumental structure. The integrated use of the non-destructive techniques described above also provides suitable data for a possible restoration and future preservation.</p><p><strong> </strong></p><p><strong>Acknowledgments: </strong>This work was partially supported by FIR (Fondi integrativi per la Ricerca) funded by the University of Cagliari (Italy). The authors would also like to thank the Ministero dei Beni e delle Attività Culturali. Polo Museale della Sardegna and Arch. Alessandro Sitzia for their kind permission to work on the <em>San Saturnino Basilica</em>.</p>

scholarly journals Three-dimensional imaging from laser scanner, photogrammetric and acoustic non-destructive techniques in the characterization of stone building materials

2018 ◽  
Vol 45 ◽  
pp. 57-62 ◽  
Author(s):  
Maria Giovanna Bianchi ◽  
Giuseppe Casula ◽  
Francesco Cuccuru ◽  
Silvana Fais ◽  
Paola Ligas ◽  
...  
Keyword(s):  
High Resolution ◽  
Building Materials ◽  
Three Dimensional ◽  
Laser Scanner ◽  
Building Stone ◽  
Data Sets ◽  
Ultrasonic Tomography ◽  
Three Dimensional Imaging ◽  
Stone Materials ◽  
D Model

Abstract. When combined, the three-dimensional imaging of different physical properties of architectural monumental structures acquired through different methodologies can highlight with efficiency the characteristics of the stone building materials. In this work, we compound high resolution Digital Color Images (DCI) and Terrestrial Laser Scanner (TLS) data for a dense 3-D reconstruction of an ancient pillar in a nineteenth century building in the town of Cagliari, Italy. The TLS technique was supported by a digital photogrammetry survey in order to obtain a natural color texturized 3-D model of the studied pillar. Geometrical anomaly maps showing interesting analogies were computed both from the 3-D model derived from the TLS application and from the high resolution 3-D model detected with the photogrammetry. Starting from the 3-D reconstruction from previous techniques, an acoustic tomography in a sector of prior interest of the investigated architectural element was planned and carried out. The ultrasonic tomography proved to be an effective tool for detecting internal decay or defects, locating the position of the anomalies and estimating their sizes, shapes, and characteristics in terms of elastic-mechanical properties. Finally, the combination of geophysical and petrographical data sets represents a powerful method for understanding the quality of the building stone materials in the shallow and inner parts of the investigated architectural structures.

scholarly journals Dermoscopic aspect of verrucous epidermal nevi: New findings

2019 ◽  
Author(s):  
ÖMER FARUK ELMAS ◽  
NECMETTİN AKDENİZ
Keyword(s):  
Polarized Light ◽  
Diagnostic Methods ◽  
The Other ◽  
Diagnostic Process ◽  
Fine Scale ◽  
Epidermal Nevus ◽  
Clinical Interpretation ◽  
New Findings ◽  
Clinical Variants ◽  
Histopathological Investigation

Background and Aim: Verrucous epidermal nevi are cutaneous hamartomas having many clinical variants. Dermoscopic features of verrucous epidermal nevus have rarely been investigated. We aimed to identify dermoscopic findings of the entity which will facilitate the diagnostic process by reducing the use of invasive diagnostic methods. Material and Methods: The study included the patients with histopathologically approved verrucous epidermal nevus. Clinical, dermoscopic and histopathological features of the patients were retrospectively reviewed and the findings identified were recorded. Dermoscopic examination was performed with a polarized-light handheld dermoscope with 10-fold magnification. Results: The most common dermoscopic features were thick brown circles, thick brown branched lines and terminal hairs. The most common vessel pattern was dotted vessels. Branched thick brown lines, brown globules, brown dots forming lines, serpiginous brown dots, white and brown exophytic papillary structures, fine scale, thick adherent scale and cerebriform structures were the other findings. Conclusion: We observed many vascular and non-vascular dermoscopic findings which have not been described previously for the entity. Dermoscopic examination of the verrucous epidermal nevi may lead more reliable clinical interpretation and thus it may reduce the need for histopathological investigation. Keywords: dermoscopy, large brown circles, verrucous epidermal nevus

scholarly journals Bearing defect diagnosis and acoustic emission

2003 ◽  
Vol 217 (4) ◽  
pp. 257-272 ◽  
Author(s):  
A Morhain ◽  
D Mba
Keyword(s):  
Acoustic Emission ◽  
Threshold Level ◽  
Diagnostic Methods ◽  
Non Destructive Testing ◽  
Test Rig ◽  
Destructive Testing ◽  
High Background ◽  
Bearing Defect ◽  
Non Destructive ◽  
Ae Counts

Acoustic emission (AE) was originally developed for non-destructive testing of static structures, but over the years its application has been extended to health monitoring of rotating machines and bearings. It offers the advantage of earlier defect detection in comparison with vibration analysis. However, limitations in the successful application of the AE technique for monitoring bearings have been partly due to the difficulty in processing, interpreting and classifying the acquired data. The investigation reported in this paper was centred on the application of standard AE characteristic parameters on a radially loaded bearing. An experimental test rig was modified such that defects could be seeded onto the inner and outer races of a test bearing. As the test rig was adapted for this purpose, it offered high background acoustic emission noise providing a realistic test for fault diagnosis. In addition to a review of current diagnostic methods for applying AE to bearing diagnosis, the results of this investigation validated the use of r. m. s., amplitude, energy and AE counts for diagnosis. Furthermore, this study determined the most appropriate threshold level for AE count diagnosis, the first known attempt.

INSPECTION BY ULTRASONIC TOMOGRAPHY (UT) LEADING TREND IN WELDING JOINT MONITORING

2015 ◽  
Vol 77 (17) ◽  
Author(s):  
Noor Amizan Abd. Rahman ◽  
Ruzairi Abdul Rahim ◽  
Nor Muzakkir Nor Ayob ◽  
Jaysuman Pusppanathan ◽  
Fazlul Rahman Mohd Yunus ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Image Resolution ◽  
Ultrasonic Tomography ◽  
Non Destructive Testing ◽  
Destructive Testing ◽  
Steel Pipes ◽  
Imaging Result ◽  
Welding Steel ◽  
Joint Monitoring ◽  
Non Destructive

Welding work is a connection process between the structure and the materials. This process is used in the construction, maintenance and repair especially mechanical engineering. This study discusses the type of welding used in the industry, mainly involving the pipeline welds. On-demand need to every work process when finishing weld requires quality tests to ensure compliance to the standards required. Monitoring through the display image has long been used in Non-Destructive Testing (NDT). Various methods of monitoring used in NDT focused on Ultrasonic Tomography (UT) as a method used in NDT and as an option for the future. Previous imaging result was in two-dimensional (2D) and then upgraded to a three-dimensional image (3D). Besides, there is potential of 3D imaging beyond the existing limits in terms of size, material thickness, especially for welding steel pipes. Achievement through research of existing pipe size so far outside diameter of 200 mm and a thickness of 5.8 mm should be limited in view of the obstacles to enhanced image resolution is less effective when compared to other tomography methods.

scholarly journals Ultrasonic Non-Destructive  Testing of Fibre Reinforced  Composites

2021 ◽  
Author(s):  
◽  
Matthew Thomson
Keyword(s):  
Experimental Work ◽  
Rayleigh Waves ◽  
Ultrasonic Waves ◽  
Reinforced Composites ◽  
Surface Cracks ◽  
Non Destructive Testing ◽  
Destructive Testing ◽  
Reinforced Composite ◽  
Non Destructive ◽  
Fibre Reinforced Composites

<p>This thesis focuses on the application of high frequency ultrasound as a tool for performing non-destructive testing for pultruded fibre reinforced composite (FRC) rods. These composite rods are popular in the manufacturing, construction and electrical industries due to their chemical, electrical and strength properties. Such FRCs are manufactured on automated production lines that operate day and night. Non-destructive testing techniques are desired to quickly and accurately detectmanufacturing flaws such as coating thickness irregularities and surface cracks. Layers and cracks can present as large changes in acoustic impedance and will strongly reflect ultrasonic waves. Combined with their low cost, east of use and absense of potentially harmful radiation, ultrasound has proven popular worldwide for Non-Destructive Testing. Finite Element Analysis (FEA) was employed to investigate the propagation of ultrasonic waves through layers of material to simulate a thickness measurement and the ability of ultrasound to measure thicknesses was proven. Experimental work was conducted on two fibre reinforced composite samples with varying thickness coatings of plastic and paint. The thickness was measured accurately using immersion transducers at 50MHz and a resolution of 20μm was attained through the use of matched filtering techniques. Surface acoustic waves, particularly Rayleigh waves were investigated using FEA techniques so that the generation, scattering and detection of such waves was understood. This lead to the development of methods for detecting surface cracks in glass using Rayleigh waves and these methods were successfully used in experimental work. Wave propagation in fibre reinforced composites was modelled and experimentally investigated with the results confirming theoretical expectations. Finally a Rayleigh wave was launched onto a fibre reinforced composite sample however the amount of energy leakage into the water was so great, due to the acoustic impedance of water, the detection of the wave was prevented. The conclusion reached was that an immersion setup was not appropriate for launching a travelling Rayleigh wave.</p>

High-Resolution 3-D Shape Integration of Dentition and Face Measured by New Laser Scanner

2004 ◽  
Vol 23 (5) ◽  
pp. 633-638 ◽  
Author(s):  
T. Sohmura ◽  
M. Nagao ◽  
M. Sakai ◽  
K. Wakabayashi ◽  
T. Kojima ◽  
...  
Keyword(s):  
High Resolution ◽  
Laser Scanner

CREEPING SURFACE LONGITUDINAL ACOUSTIC WAVE: MAIN PROPERTIES AND APPLICATION POSSIBILITIES

2021 ◽  
pp. 4-12
Author(s):  
V. G. Shevaldykin
Keyword(s):  
Critical Angle ◽  
Flaw Detection ◽  
Ultrasonic Signal ◽  
Ultrasonic Waves ◽  
Concave Surface ◽  
Ultrasonic Tomography ◽  
Transverse Waves ◽  
Near Surface ◽  
The Third ◽  
Creeping Wave

Creeping ultrasonic waves have long been successfully used for flaw detection of near-surface and near-bottom zones of metal products. However, due to the fact that the creeping wave generates a lateral transverse wave directed into the metal volume at the third critical angle, it is also possible to test internal defects in principle. At known velocities of propagation of longitudinal and transverse waves in the metal, the third critical angle is easily calculated. Therefore, the time of propagation of the ultrasonic signal along any trajectory between points on the surface and in the volume of the metal can be calculated. Usually, creeping waves are used to test products of plane-parallel shape. There are no cases of their application on curved surfaces in the literature. It is possible that the creeping wave can also propagate over a concave surface. The aim of the article is to test experimentally new ways of using creeping waves. The propagation trajectories of the creeping and lateral transverse waves were studied on a steel plate. The time of passage of the ultrasonic signal along such trajectories of different lengths was measured, and the measurement results were compared with the calculated time values. The measured and calculated values coincided with accuracy sufficient for the coherent accumulation of echo signals that passed through the metal part of the path by the creeping wave and another part of the path by the lateral transverse wave.The propagation of the creeping wave over a concave surface was studied on a steel sample with cylindrical faces of different radii. As a result, it turned out that on a concave surface, the creeping wave propagates at the same speed of longitudinal waves as on a flat surface, but it decays much more strongly with distance. Studies have shown that creeping waves can be used in ultrasonic tomography, where a preliminary calculation of the propagation trajectories of ultrasonic signals is required. The propagation of creeping waves over concave surfaces extends the capabilities of the TOFD method to the area of intube testing

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