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Page 196 of 977 Results 1951 - 1960 of 9762

Angela Ferrante, Ersilia Giordano, Francesco Clementi, Gabriele Milani, Antonio Formisano
The Non-smooth tale of Apennine Churches stroked by the Central Italy Earthquakes of 2016

The dynamic behavior and the seismic vulnerability of different masonry Apennine Churches, dramatically damaged by the last shocks sequence of 2016 that occurred in Central Italy, have been studied in this paper by means of advanced 3D numerical analyses with the Discrete Element Method (DEM). Thus, a discontinuous approach has been used to assess the dynamic properties and the vulnerability of the masonry structure, through large deformations regulated by the Signorini s law, concerning the impenetrability between the rigid bodies, and by the Coulomb s law, regarding the dry-friction model. The major purpose of this study is to highlight that relevant data on the real structural behavior of historical masonry can be provided through advanced numerical analyses. The comparison between the results of the numerical simulation and the survey of the existing crack pattern of the churches permitted to validate the used approach. Finally, from the results and conclusions of these cases study, it is possible to affirm that the used methodology can be applied to a wide variety of historical masonry structures in Europe.

Antonia Spanò
Rapid Mapping methods for archaeological sites

The paper focuses the feasibility of rapid mapping methods in archaeological site, enlightening the flexibility in different kind of ancient buildings and sites surveying with the aim to 3D document and to model objects of interest with rich geometric and radiometric contents and high accuracies. After discussing constraints to be considered for the correct use of rapid mapping methods, a case study will be described in which an UAV photogrammetry survey, integrated with a terrestrial survey using a mobile laser scanner based on SLAM technology (Simultaneous Localization and Mapping) was performed. A Lidar (terrestrial laser scanner - TLS) survey as ground truth, that accompanies the use of ground control points for the evaluation of the metric results, completed the application. The case study is a great importance area in the ancient city of Hierapolis (TK), the Ploutonion, in which excavations were recently completed and the public exhibition was inaugurated (2018). The test case represents an example in which the advanced Geomatics technologies offer multiple challenging outcomes of experimental use of 3D dense models generated by imaging and ranging technologies. In addition to 3d points models, the two-dimensional architectural representation results at different scales will also be briefly discussed.

Mattia Previtali, Lucia Díaz-Vilarino, Marco Scaioni, Ernesto Frías Nores
Evaluation of the Expected Data Quality in Laser Scanning Surveying of Archaeological Sites

Laser Scanning is nowadays more and more widespread for documentation of archaeological sites. To guarantee a proper survey, especially in the case of large archaeological site, several parameters need to be taken into consideration to guarantee the effectiveness of the documentation. In particular, these account for data accuracy, density and completeness. Generally, scan planning is empirically based on the personal experience of the operator. This paper presents a more controllable and reliable way for scan planning optimization. The presented methodology is based on a two-step approach. In the first step, starting from a preliminary plan of the site to be surveyed, a ray tracing algorithm is applied to a set of scan point candidates and finally the scan position optimization is based on a backtracking algorithm, considers a minimum scene coverage as stopping criterion. In the second step, starting from the previously defined positions, scans are simulated to derive the expected scan accuracy, density and completes. The presented methodology is tested on two archaeological sites the Grandi Horrea of Ostia (Italy) and the Basilica di Massenzio in Rome (Italy).

Manuel J.H. Peters, Tesse D. Stek
Modelling the Seventies: Image-Based Modelling to Investigate Landscape Change in a Mediterranean Mountain Area

Historical aerial imagery can be used to investigate geomorphological change over time, which can inform research about the preservation and visibility of the archaeological record, as well as heritage management. This paper presents a composite Image-Based Modelling workflow to generate 3D models, historical orthophotos, and historical digital elevation models from images from the 1970s. The main challenge was the lack of high-resolution recent digital elevation models and ground control points. Therefore, spatial data from various sources had to be combined. To assess the accuracy of the final 3D model, the RMSE was calculated. While the workflow appears effective, the low accuracy of the initial data limits the usefulness of the model for the study of geomorphological change. However, it can be implemented to aid sample area selection when preparing archaeological fieldwork, or, when working with different survey datasets, signal areas with a high bias risk resulting from postdepositional processes.

E. Angelats, M. E. Parés, C. Mas-Florit, M.A Cau-Ontiveros
A methodology for semi-automatic documentation of archaeological elements using RPAS imagery

One of the main tasks of archaeologists is to document (map) their sites at a level where stones may be clearly distinguished and to provide centimetrelevel reliable measurements of man-built structures. One of the goals of the project ARCHREMOTELANDS is to develop a methodology to generate those maps semi-automatically combining RPAS imagery, photogrammetry and machine learning techniques. In this context, this paper presents a conceptual framework to determine the minimum number of pixels, and so the required Ground Sampling distance and altitude needed to fly a RPAS allowing very detailed documentation and digitalization of archaeological sites by processing the acquired images. These images are used firstly to generate a high resolution orthophoto. Then, archaeological elements of interest are documented almost automatically using 2D unsupervised clustering techniques. The approach has been experimentally tested and validated in the early Christian complex of Son Peretó (Manacor, Mallorca, Spain).

Efstathios Adamopoulos, Fulvio Rinaudo
An Updated Comparison on Contemporary Approaches for Digitization of Heritage Objects

Continuous developments on sensors, data acquisition techniques, algorithms and computational systems have enabled automation, higher processing velocities and increased metric accuracy regarding the modeling of tangible heritage. For applications on heritage artefacts or architectural details, scanning and photogrammetric systems based on structure-frommotion (SfM) approach have prevailed, due to lower costs, fast acquisition and processing, re-producibility of workflows and ability to capture high-resolution texture. This study presents an updated comparison of contemporary digitization approaches to examine in extent required processing stages, compare costs and evaluate produced 3D results according to their metric properties, quality of texture and visual fidelity.

Giovanni Chimienti, Francesco Mastrototaro
What do marine zoologists need from an underwater vehicle?

Future perspectives in underwater vehicles potential uses and needed features are here presented and discussed through different study cases embracing research, monitoring and exploration, from shallow-water to deep-sea habitats and communities. Essential features asked to the next generation of underwater vehicles include the possibilities to explore deeper depths, observe in detail targeted specimens, use further spectra besides the visible, sample soft-body benthic organisms, move within demanding situations (e.g. obstacles on the seabed), as well as the ability to stably stop on the seabed and collect images in a relative long (e.g. few hours) time spam.

Simone Zazzini, Michela De Dominicis, Agnese Pini, Giovanni Leuzzi, Paolo Monti, Rory O Hara Murray, Xiaorong Li
Turbulence changes due to a tidal stream turbine operation in the Pentland Firth (Scotland, UK)

The high tidal stream resource in the Pentland Firth (Scotland, UK) has encouraged the development of commercial scale tidal farms. This work is a modelling study primarily focused on how the layout of arrays determines the extractable power and may affect physical processes in the region. Furthermore, the study provides information about submarine turbine maintenance. Tidal dynamics in the Pentland Firth and Orkney Waters (PFOW) have been reproduced by a three-dimensional FVCOM model implementation. The tidal stream turbines were represented in the model as sub grid scale objects by using a momentum sink approach. It has been explored how different turbine location, number and spacing can allow achieving very different amount of power resource, as well as degree of change to flow velocities. It has also been verified that turbulence changes can lead to an increase in bottom currents in the vicinity of the tidal turbines.

Daniele S. Terracciano, Vincenzo Manzari, Mirko Stifani, Benedetto Allotta, Andrea Caiti, Giuseppe Casalino
SEALab current research trends: Maritime Unmanned Systems for dual-use applications

The technological potential offered by Maritime Unmanned Systems (MUS) is recognized by many countries as an effective tool for both military and civilian applications. The increasing use of MUS brought substantial and new challenges to the Test and Evaluation process that becomes significantly more complicated than traditional systems. Unmanned systems have continuously increasing complexity and capabilities and can be at different maturity levels. These technologies necessitate for specific Test and Evaluation tools throughout the whole program life cycle. For the above reasons, the Naval Support and Experimentation Centre (CSSN) of the Italian Navy and the Italian Interuniversity Center on Integrated Systems for the Marine Environment (ISME) founded a joint laboratory in 2015, called SEALab (Laboratory on marine heterogeneous and autonomous systems), with the main goal to jointly develop and manage applied research and experimentation activities of common interest in the field of heterogeneous and autonomous marine systems.

Mouldi Ben Meftah, Elvira Armenio, Diana De Padova, Francesca De Serio, Michele Mossa, Davide Tognin
Experiments on Coupled Wave-Flow-Vegetation Interaction

In this study we focus on how understanding, through experimentation using advanced techniques, the dynamic of wave interaction with emergent vegetation. In order to achieve this objective, an experimental study of wave mention through an infinite array of emergent cylinders distributed along a channel bottom was carried out in the Coastal Laboratory at the Polytechnic University of Bari (Italy). A series of sophisticated equipment was used to produce and measure the details of this phenomenon, including essentially an electro-valve, equipped with an electromagnetic flow meter and a control device to rapidly open and close it to generate the water waves, a series of ultrasound probes to measure the free surface elevation, and a series of Acoustic Doppler Velocimeter (ADV) probes in addition to a Particle Image Velocimetry (PIV) technique for flow velocity measurements. The measurement methods, instrument calibration, data filtration and some preliminary results are reported in this study.

Page 196 of 977 Results 1951 - 1960 of 9762