Studio dell'interazione tra moto ondoso e strutture marittime mediante modellazione fisica

2012 - 2013Le aree costiere rappresentano sistemi naturali del tutto unici, così come unici sono i fenomeni che le caratterizzano. L’erosione dei litorali, divenuta ormai un fenomeno di interesse planetario, ha spinto verso un approfondimento delle conoscenze dei processi costieri, consentendo di operare nella lotta ai suddetti fenomeni, attraverso strategie sempre più mirate e attente. Una migliore conoscenza dei processi costieri, infatti, può consentire agli ingegneri di adottare approcci più corretti nella progettazione di opere di protezione costiera. La principale fonte di supporto per l’ingegneria costiera è rappresentata dalla letteratura tecnica e scientifica relativa ad interventi già posti in essere nel passato. Strumenti di conoscenza aggiuntivi possono essere forniti da fonti di diversa natura. Uno su tutti la modellistica fisica, che rappresenta senza dubbio un importantissimo mezzo di conoscenza al servizio della progettazione del tipo di opere in parola. Tramite la modellistica fisica è possibile, ad esempio, studiare fenomeni quali la propagazione del moto ondoso nel suo percorso dal largo verso riva, l’agitazione ondosa all’interno dei porti, la stabilità delle strutture sottoposte alle azioni dinamiche del moto ondoso, così come il wave runup, l’overtopping, la riflessione e la trasmissione ad esse associati. Si tratta di fenomeni la cui conoscenza risulta di fondamentale importanza quando nasce l’esigenza di progettare un’opera di difesa costiera. E il risultato è tanto migliore, quanto più sono specifiche le conoscenze su cui viene fondato il progetto. Si consideri, ad esempio, il caso delle dighe a scogliera, il cui strato di armatura più classico è costituito da massi naturali di grandi dimensioni: laddove non ci dovesse essere sufficiente disponibilità del suddetto materiale, o laddove si sia in presenza di condizioni meteomarine particolarmente gravose, le unità di armatura in massi naturali vengono normalmente sostituite da unità in calcestruzzo, per le quali esiste ormai una gran varietà. E’ evidente che, a seconda della forma e delle dimensioni delle suddette unità, nonché del numero di strati con cui esse vengono posizionate sulla mantellata, cambia sensibilmente il comportamento idraulico della struttura. Ne consegue la necessità, in fase di progettazione, di poter disporre di parametri che siano caratteristici della tipologia di unità di armatura della mantellata che si deve realizzare. L’individuazione dei suddetti parametri deve essere necessariamente il risultato di prove sperimentali eseguite in laboratorio su modelli fisici di strutture realizzate con quelle specifiche unità di armatura. Oggetto del presente lavoro, dunque, è lo studio dei fenomeni che intervengono nell’interazione tra il moto ondoso e le strutture di difesa costiera, in particolare per un’opera a gettata costituita da una tipologia di unità di armatura in calcestruzzo non presente in mercato, attualmente sottoposta a procedura brevettuale. Il lavoro è stato condotto mediante sperimentazione su un modello fisico bidimensionale realizzato presso il Laboratorio di Ricerca e Sperimentazione per la Difesa delle Coste (LIC) del Dipartimento di Ingegneria Civile, Ambientale, del Territorio, Edile e di Chimica (DICATECh) del Politecnico di Bari. Lo studio ha permesso di individuare alcuni parametri caratteristici delmasso in oggetto, quali ad esempio il coefficiente di stabilità e il coefficiente di scabrezza, necessari per il calcolo delle grandezze con cui poter effettuare il dimensionamento dell’opera. Inoltre, sono state valutate alcune delle formulazioni presenti in letteratura per il calcolo delle suddette grandezze, al fine di analizzare la loro adattabilità al nuovo masso. [a cura dell'autore]XII n.s

Exploiting remote imagery in an embayed sandy beach for the validation of a runup model framework

International audienceStorm surge and wave runup are key determinants of the potential for beach overwashing during storm events. However, the prediction and quantification of wave runup on embayed beaches is strongly influenced by particular characteristics (e.g., irregular morphology, low tides, absence of swell, etc.) which differ from those on open beaches, and have rarely been investigated in literature. In the present paper, a model framework aimed at predicting wave-induced runup on an embayed sandy beach is validated by means of measurements derived from a video-monitoring station, recently installed in South Italy, during two storm events in 2016. The numerical approach employs MeteOcean forecasted waves within SWAN and SWASH models (in both 2-d and 1-d mode). The combination of multibeam and d-RTK surveys with Unmanned Aerial Vehicle (UAV) imagery provides high resolution depth grid (m 0.015), particularly required in shallow waters, where wave hydrodynamics is highly influenced by the bottom. The results show and discuss the agreement between video measurements and 2-d predictions of runup. A sensitivity analysis of the Manningfls roughness factor is needed in 1-d simulations. The accuracy of the empirical formulas in predicting wave runup in an embayed beach is also investigated , showing mainly an overestimation of the observations

A Sterescopic System to Measure Water Waves in Laboratories

A new system for estimating the synthetic parameters of sea states during physical investigations has been implemented. The technique proposed herein is based on stereographic analysis of digital images acquired with optical sensors. A series of ad hoc floating markers has been made and properly moored to the bottom of a large wave tank to estimate the synthetic parameters of generated waves. The implemented acquisition system and the proposed algorithm provide automatic recognition of all markers by a pair of optical sensors that synchronously captures their instantaneous location and tracks their movements over time. After transformation from the image to the real-world coordinates, water surface elevation time series have been obtained. Several experimental tests have been carried out to assess the feasibility and reliability of the proposed approach. The estimated wave synthetic parameters have been then compared with those obtained by employing standard resistive probes. The deviation were found to be equal to ~6% for the significant wave height and 1% for peak, mean, and significant wave periods

2017 HRS/EHRA/ECAS/APHRS/SOLAECE expert consensus statement on catheter and surgical ablation of atrial fibrillation: executive summary.

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2017 HRS/EHRA/ECAS/APHRS/SOLAECE expert consensus statement on catheter and surgical ablation of atrial fibrillation: executive summary.

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withdrawn 2017 hrs ehra ecas aphrs solaece expert consensus statement on catheter and surgical ablation of atrial fibrillation

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A Combined Approach of Field Data and Earth Observation for Coastal Risk Assessment

The traditional approach for coastal monitoring consists in ground investigations that are burdensome both in terms of logistics and costs, on a national or even regional scale. Earth Observation (EO) techniques can represent a cost-effective alternative for a wide scale coastal monitoring. Thanks to the all-weather day/night radar imaging capability and to the nationwide acquisition plan named MapItaly, devised by the Italian Space Agency and active since 2010, COSMO-SkyMed (CSK) constellation is able to provide X-band images covering the Italian territory. However, any remote sensing approach must be accurately calibrated and corrected taking into account the marine conditions. Therefore, in situ data are essential for proper EO data selection, geocoding, tidal corrections and validation of EO products. A combined semi-automatic technique for coastal risk assessment and monitoring, named COSMO-Beach, is presented here, integrating ground truths with EO data, as well as its application on two different test sites in Apulia Region (South Italy). The research has shown that CSK data for coastal monitoring ensure a shoreline detection accuracy lower than image pixel resolution, and also providing several advantages: low-cost data, a short revisit period, operational continuity and a low computational time

Telerehabilitation of cognitive, motor and sleep disorders in neurological pathologies: the REHOME project

Telemedicine and considered fundamental pillars to ensure the sustainability of the health system in the next future. In fact, the aging of the population, and the consequent growing percentage of people suffering from neurological pathologies and related disabilities, require more and more resources from healthcare facilities in terms of monitoring and rehabilitation services. Solutions based on Information and Communication Technologies can support new patient care and disease management strategies, by deploying telemedicine applications and services. In this context, the paper presents the integrated platform implemented in the “REHOME” project, for the remote monitoring and rehabilitation of cognitive, motor, and sleep disorders caused by neurological diseases. The solution integrates sensors and innovative methodologies to face patients’ and clinical needs by ensuring the continuity of care and rehabilitation services from health facilities to domestic scenarios

Innovative Strategies, Monitoring and Analysis of the Coastal Erosion Risk: the STIMARE Project

Coastal erosion processes are often due to inappropriate coastal defense strategies. The construction of infrastructures that interfere with the coastal circulation and the sediment transport along the coast (piers, docks, etc.), the destruction of the dunes and other anthropogenic modifications to the beach, are some of the factors that limit the adaptability of the beach system and amplify the risk of erosion and flooding of the coastal land. Coastal defense interventions have historically been based on the construction of rigid works (seawalls, groins, breakwaters, jetties, etc.), which, while protecting the territory, have often shifted the problem of erosion to the neighboring coasts. The paper will present the contents and the first findings of the research project STIMARE (Innovative strategies, monitoring and analysis of the coastal erosion risk), financed by the Italian Ministry of the Environment and the Sea (MATTM), aimed to define strategies for coastal management, based on a strong involvement of the stakeholders, and on the use of innovative or low-costs technologies for coastal monitoring. Methodology is based on data acquisition, numerical modelling, laboratory tests, physical and ecological monitoring. All the information and results will be discussed with the local stakeholders, in order to provide a comprehensive strategy for coastal protection, following the European Marine Strategy framework. The Project involves researchers from two important Universities in Italy (University of Bologna and Politecnico di Bari) and has a strong interdisciplinary approach, involving coastal engineers, urban planners, geologists, ecologists and mechanical engineers