Papers by Antonio Scamardella
Nav 2012 17th International Conference on Ships and Shipping Research, Sep 14, 2012
Coastal Engineering Journal, 2015
Ocean Coastal Management, 2013
In this paper the first field measurements of wake wash produced by High Speed Craft (HSC) operat... more In this paper the first field measurements of wake wash produced by High Speed Craft (HSC) operating in the Bay of Naples are presented. The fleet in service in the Bay is analysed and the main characteristics of these units are given. Their routes are monitored and three critical points, where the distance from the coast is less than 700 m, for wake wash investigation were identified. In two of them a pressure gauge was installed and the field measurements of wake wash were performed. While wake wash was recorded by the pressure gauge, contemporaneously the route was monitored aboard the crossing HSC and exact speed, distance from the monitored site, and water depth were determined. The recorded wake wash measurements are analysed and maximum wave height and corresponding period are identified for each registration. The obtained values are compared with the International Rules and at last some comments and conclusions are given.
International Journal of Naval Architecture and Ocean Engineering, 2015
In ambito aeronautico e navale la modellazione inversa di eliche e superfici tridimensionali dall... more In ambito aeronautico e navale la modellazione inversa di eliche e superfici tridimensionali dalla forma geometrica complessa rappresenta uno degli argomenti di maggiore interesse per verifiche di conformità al progetto iniziale, analisi delle performance e individuazione di possibili deformazioni intervenute nel tempo. In particolare, la progettazione di eliche è molto delicata e richiede modelli di calcolo specifici, funzione del mobile su cui l'elica sarà installata, del fluido in cui essa sarà immersa e dei parametri propulsivi da realizzare. Il numero di pale, la forma delle sezioni di pala, il diametro, il passo, ecc. determinano le performance propulsive; il controllo accurato di tali parametri geometrici rappresenta quindi un passo obbligato prima del definitivo montaggio sul mobile. In questo lavoro sono esposte le procedure di reverse engineering per la ricostruzione del modello digitale di un'elica allo scopo di determinarne i parametri geometrici caratteristici e/o confrontarne i valori con quelli costruttivi di progetto. Le tecniche di reverse engineering utilizzate nei test eseguiti sono la fotogrammetria e il laser scanning; entrambe sono state usate su un modello in scala, per il quale sono stati effettuati anche i relativi confronti, mentre su eliche al vero, a causa di difficoltà logistiche, è stata utilizzata la sola tecnica fotogrammetrica. La particolarità delle forme delle eliche da rilevare (con pale spesso parzialmente ricoprentesi) ha imposto un'attenta fase di progettazione delle scansioni laser e delle prese fotogrammetriche, in particolare per queste ultime che devono coprire stereoscopicamente ogni recesso. La prima elica oggetto di studio è una ORVEA, appartenente alla serie sistematica denominata B-Wageningen il cui diametro, pari al passo, è di 180 mm ( , modello in scala, di elevata precisione costruttiva, utilizzato per prove in vasca. Il laser scanner usato per tale rilievo è un desktop 3D scanner HD triangolatore, a basso costo, della NEXTENGINE con il quale sono state eseguite undici scansioni da una distanza media di circa 40 cm. Le nuvole di punti delle diverse scansioni sono state allineate mediante procedure ICP implementate nel software NEXTENGINE ScanStudio HD a corredo del laser. La procedura di allineamento richiede una rototraslazione manuale approssimata mediante punti omologhi riconosciuti sulle diverse scansioni. A tal fine sono stati incollati sulla superficie delle pale e del mozzo alcuni target codificati, utili anche per la fase di orientamento automatico delle prese fotogrammetriche. Il rilievo fotogrammetrico è stato eseguito con una camera Fuji S5600 da 5 Mpx e un obiettivo avente una focale nominale di 6.3 mm, preventivamente calibrata nella stessa condizione di distanza e diaframma utilizzata per le prese dell'elica. Data l'omogeneità della trama e la lucentezza della superficie metallica, è stato necessario un trattamento preventivo dell'elica stendendo un sottile strato di borotalco e gesso colorato. Le prese fotogrammetriche sono state eseguite in laboratorio con luce controllata e diffusa mediante un set auto costruito per fotografia still-life in modo da ridurre le riflessioni speculari, possibili cause di fallimento nel processo di image-matching. Il modello fotogrammetrico di 63 immagini a scala media del fotogramma pari a 1/27 è stato eseguito con la procedura Bundle-Adjustment implementata nel software Photomodeler 5.2.3. Per il dimensionamento è stata utilizzata una barra calibrata di acciaio C40 posta come base d'appoggio dell'elica in modo da essere ben visibile su numerose immagini. Per determinare un DSM denso che permetta la ricostruzione della superficie di un oggetto 3D come un'elica, è necessario suddividere tale superficie in segmenti tali che possano essere considerati 2.5 D. Ciò implica che per ogni segmento è necessario un sistema di riferimento idoneo, che consenta quindi di 212
ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 2011
Since 2003, Barcelona charter has highlighted the importance of digital recording of historic shi... more Since 2003, Barcelona charter has highlighted the importance of digital recording of historic ships and maritime heritage in general. Despite this has been stressed with emphasis, three dimensional modelling of maritime cultural heritage is still not usual as for archaeology and architecture. Three-dimensional modelling in the maritime heritage needs particular requirements. Objects to be recorded range from small replicas in maritime museums up to full-scale vessels still in operation. High geometric accuracy, photorealism of final model and faithful rendering of salient details are usually needed, together with the classical requisites characterising the 3D modelling-from-reality process, i.e. automation, low cost, reliability and flexibility of the modelling technique. In this paper, a hybrid multi-technique approach is proposed for maritime heritage preservation and, as case study, the 3D modelling of a 3-meter-long scale model of a historic warship, the "Indomito", is presented. The survey is placed in a wider project aiming to realize the virtual maritime museum of Parthenope University of Naples, for making it available to a wider public and also preserving its cultural heritage. Preliminary results are presented and discussed, highlighting relevant aspects that emerged during the experiment.
Marine Structures, 2014
The paper focuses on time-variant longitudinal strength of bulk carriers under corrosion wastage,... more The paper focuses on time-variant longitudinal strength of bulk carriers under corrosion wastage, applying both Taylor series expansion method and Monte Carlo simulation. Hull girder section modulus and ultimate bending moment capacity are determined, by classical beam theory and the commonly applied incrementaliterative approach, respectively. Two main aspects are fully discussed and investigated, according to the final recommendations of last ISSC Report. The former regards the covariance between annual corrosion rates of individual structural members, commonly assumed as uncorrelated. Really, as it is conceivable that a certain correlation exists, three different cases are investigated: uncorrelated variables, fully correlated variables, full correlation between structural members belonging to the same category of compartments. The latter investigates the probability density function of both hull girder section modulus and ultimate bending capacity, because the Central Limit Theorem cannot be applied when correlation among random variables exists. Finally, as a test example, the bulk carrier section, presented in the last ISSC benchmark study, is analysed.
Ocean Engineering, 2014
The paper deals with the catenary mooring system design for tri-floater floating offshore wind tu... more The paper deals with the catenary mooring system design for tri-floater floating offshore wind turbines. Both ultimate (ULS) and accidental (ALS) limit states are examined, under 50 and 1 year return period environmental loads. Both power production and parked wind turbine conditions are analysed; for the former the ULS is applied, for the latter both ULS and ALS are considered. The platform static demand is assessed in terms of turbine thrust, wind, current and wave steady drift forces. The dynamic offset is determined considering both wave and low-frequency motions. Mooring patterns with 6, 9 and 12 chain cable and steel wire rope lines are considered. Water depth incidence is examined in the range between 50 and 300 m and the mooring system is dimensioned so that the relevant weight is determined. The Dutch tri-floater is assumed as reference structure and three candidate sites in the Southern Mediterranean Sea are considered. It is found that platform admissible offset and line pattern significantly influence the mooring system weight; obtained results show that 9 and 12 line configurations are the necessary choice and the mooring line weight is independent of water depth between 100 and 200 m, while increases out of this range.
Journal of Marine Science and Technology, 2014
ABSTRACT The present study focuses on wake wash management in the Bay of Naples by time variant s... more ABSTRACT The present study focuses on wake wash management in the Bay of Naples by time variant spectral analysis to establish more reliable operational strategies and mitigative measures. The time frequency analysis of several wake wash signals due to high-speed craft (HSC), both catamarans and monohulls, operating in the Gulf of Naples is carried out to derive the time-energy per unit area distribution and better characterize the wake wash event and relevant spectrum. A new spectral analysis procedure, which allows to filter the wind sea wave component, is proposed to evaluate the only wake wash component and to estimate both wake wash height and energy density. In this respect, in fact, the influence of wind sea waves may lead to more reliable coastal management guidelines and wake wash measures, even if the measurement campaign has been carried out under calm met-ocean conditions. A comparative study with wake wash values determined by time history analysis is finally carried out, showing that spectral analysis can be applied with good confidence for coastal management purposes, leading to more accurate and reliable operational strategies.
Procedia Engineering, 2014
This paper deals with the mooring control of tri-floater support structures for wind turbines by ... more This paper deals with the mooring control of tri-floater support structures for wind turbines by means of a numerical parametric study; both catenary and vertical tensioned mooring lines are considered. Operational and extreme climate conditions are examined, in particular wave, wind and current parameters with return periods of 5 and 50 years are determined for three different locations in Southern Mediterranean Sea. Mooring system is dimensioned in such a way that the offset due to environmental actions is restrained within allowable limits. The response of the platform is assessed in terms of: static forces due to turbine thrusts, wind and current drag forces and steady drift forces; the wave frequency motion RAO curves; the low frequency second order wave motions. Finally, assuming the Dutch tri-floater structure as a test case, a parametric study is carried out to identify the most suitable mooring configurations, varying the water depth in the range between 50 and 200 m.
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Papers by Antonio Scamardella