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An extensive experimental investigation on four SWATH hull forms has been conducted in calm water and in regular waves at University of Naples Federico II. Calm water tests have been analyzed in the range of Froude number FrT from 0.1 to 0.6. For all four SWATH configurations at the speed, corresponding to FrT 0.32, the behaviour in regular waves has been tested. The results of heave, pitch and vertical accelerations are presented in nondimensional form as RAO. For the “most promising” SWATH #4 configuration, a set of stabilizing fins have been designed and an active stabilization system has been developed. The developed SWATH#5 has been tested in calm water on three displacements in the range of FrT from 0.1 to 0.65. The dynamic wetted surface has been identified and the residual resistance coefficient CR as well as RT/Δ are reported. Seakeeping tests have been performed in regular head sea and in head and following irregular sea at FrT = 0.50. The conditions for the occurrence of dynamic longitudinal instabilities have been identified. The results allows to comment the effect of slenderness of struts and SWATH’s immersed bodies on resistance and seakeeping and concerns the applicability of SWATH concept to small craft.

Hull forms of high-performance sailing dinghies are very interesting for yacht designers. After a long period in which the attention has been focused on one-design boats, in recent years a few exciting restricted classes such as International Moth, International 14′, 18’ Skiff and Class A catamaran become recognized in several countries and led to interesting advances in high-performance yacht design. “1001VELAcup R3” class is two people racing dinghy designed according to a box rule with limitation on LOA and Bmax and total sail area. The boats must be designed and built by students of European Universities and race yearly in Italy. This paper focuses on two best-ranked boats “LED” from the University of Palermo and “TryAgain” managed by the University of Naples but designed by the University of Roma3 team. These boats were definitely superior as regard motion resistance when tested without appendages during 2017 MIDWINTER INDOOR RACE and, although very different in main section shape, had comparable performances. The observed behaviours and the availability of experimental data suggested a suitable numerical approach and a fair comparison between experimental and numerical results is presented.

The fatigue delamination process of three different aeronautical quality composites subject to mode III fracture loading is studied experimentally in this paper with the aim of analysing the effect of the type of matrix used under this fatigue fracture mode. In all cases, the main difference between the composite materials considered in this study is the type of epoxy resin used as the matrix.The test method used to produce the delamination process under mode III fracture is known as the Longitudinal Half Fixed Beam (LHFB) method, used in previous studies by the authors, which was shown to be a valid method for generating the delamination process in composite sheet materials subject to mode III fatigue loading.The experimental data from the fatigue tests were treated with a probabilistic model based on the Weibull distribution. This model facilitates the identification of relevant aspects of the fatigue behaviour of these materials, such as the estimation of fatigue strength for periods of time greater than those tested here, as well as the reliability of the results.The results thus obtained reflect important differences in the fatigue behaviour of the materials under study, the type of matrix being the predominant parameter of the fracture process under mode III loading. Keywords: Delamination, Fracture, Fatigue, Mode III

The modelling of planing craft dynamics in waves and related fluid-structure interaction is a hard challenge due to the highly nonlinear, transient and stochastic nature of the whole process. This paper explores the prospectives of detailed experimental modelling of the local structure responses for high-speed planing craft in waves. A novel experimental setup is presented where a well-defined model structure is integrated into the hull bottom of a typical planing craft model. The model is instrumented for measuring strains in the model structure, related slamming pressures, craft rigid body motions and accelerations. The experimental setup is thoroughly described and motivated and crucial aspects of the setup are verified through testing in idealized static loading conditions and by modal analysis. The capabilities of the experimental setup are demonstrated through systematic experiments in regular waves. The most indicative results are presented and discussed in relation to corresponding results from time-domain simulations. The presented experimental modelling approach is concluded to enable uniquely detailed studies of the complete slamming related fluid-structure interaction process and provides a good tool for further research and development towards establishment of first principles-based methods for hydrodynamic and structure design of high-speed planing craft.

A proper design of the mooring systems for Wave Energy Converters (WECs) requires an accurate investigation of both operating and extreme wave conditions. A careful analysis of these systems is required to design a mooring configuration that ensures station keeping, reliability, maintainability, and low costs, without affecting the WEC dynamics. In this context, an experimental campaign on a 1:20 scaled prototype of the ISWEC (Inertial Sea Wave Energy Converter), focusing on the influence of the mooring layout on loads in extreme wave conditions, is presented and discussed. Two mooring configurations composed of multiple slack catenaries with sub-surface buoys, with or without clump-weights, have been designed and investigated experimentally. Tests in regular, irregular, and extreme waves for a moored model of the ISWEC device have been performed at the University of Naples Federico II. The aim is to identify a mooring solution that could guarantee both correct operation of the device and load carrying in extreme sea conditions. Pitch motion and loads in the rotational joint have been considered as indicators of the device hydrodynamic behavior and mooring configuration impact on the WEC.

During an atmospheric re-entry, several spacecraft’s components, in particular high pressure tanks are known to survive. Some have been found on different locations worldwide. The current design baseline of such tanks consists of Titanium liners with carbon composite overwrapped. This paper aims at presenting simulations of the thermal behavior of new baselines that would be destroyed during their atmospheric reentry. New tools and processes have been developed to quickly and accurately give technical feedbacks to engineers about the survivability of particular designs. Design for Demise, as new discipline, is playing a bigger role in new spacecraft developments, like the Ariane 6 launcher.

The Second Generation Intact Stability Criteria (SGISC) have been introduced after the occurrence of stability-related accidents, which clearly demonstrated that “actual” intact stability criteria were not adequate. New generation criteria are based on the physical and failure mode analysis of parametric roll, pure loss of stability, surf-riding/broaching, dead ship condition and excessive accelerations. This paper is focused on the verification of surf-riding/broaching vulnerability criterion of semi-displacement hull form of the Systematic Series D by Kracht and Jacobsen (1992) representative of several naval ships built during 90ties. Levels 1 and 2, as amended in IMO relevant documents, have been calculated for all seven D Systematic Series ships from resistance and propulsion performances measured in calm water. After several and counteracting changes in the wave celerity definition by IMO, the calculations have been performed for all models with both linear and non-linear formulation. The influence of the diffraction component on the wave surging force has been analyzed according to the works of Feng et al. (2015, 2017). The total surge force, calculated by 3D panel method, has been compared against actual IMO formulation and calculation of vulnerability has been performed for three hulls. The limit Froude number for the considered 90 m ships is increased by improving the accuracy of 2nd level calculation, taking into account only nonlinear wave celerity or diffraction component and linear wave celerity.

Slamming pressure assessment is an important topic for shell plating and stiffener design of bow flare. In this study, the pressure distribution on the bottom plating of an high speed planning craft is evaluated through measurements of the impact pressures on scale model running in regular waves. The planing hull model, monohedral hard chine built with clear bottom and deck, in order to allow the visual inspection of the fluid flow and the exact points of impact has been extensively studied as reported in previous works. From the time histories of vertical motions (heave and pitch) and bow acceleration of the model measured in “standard” seakeeping tests, preliminary assessment of the slamming impact pressure according to Zhao and Faltinsen method is performed. The experimental campaign presented in this paper is focused on the pressure field assessment in nine points of the hull bottom surface running at four velocities and two regular waves. Results analysis in time and frequency domain is given, identifying the pressure distribution along the bottom panel. Furthermore, comparison of measured, analytical and normative values has been performed. From the cross-correlation of measured responses further comments and indications for future work has been withdrawn. The reported results provide an useful data set for all transportation-engineering systems under dynamic load.

A series of hard chine planing hull forms was developed at Department of Naval Architecture, University of Naples. Three warped and one monohedral hulls were designed and four 6 ft long models were built. The models have the same transversal section at 0.25 L from the stern with 16.7 degrees deadrise angle. Warped models had deadrise angle linearly varying along the hull length. Aim of the experimental program is the evaluation of the effect of deadrise angle variation along the hull length on hydrodynamic resistance and on seakeeping although this work presents calm water performances only. The models have clear polycarbonate bottom to allow flow visualization and accurate wetted surface assessment. Resistance tests were performed for speed coefficient CV ranging from 0.56 to 3.92 and for two load coefficient values: CΔ=0.428 and 0.392. Reported results are wetted lengths of pressure area and whisker spray area, projected angles of stagnation line, wetted surface and whisker spray area, residual resistance coefficient, sinkage, presented in standard non-dimensional form, and running trim.

This paper presents an experimental research for the assessment of pressure field on the bottom of a mono-hedral hard chine hull at high relative speed. Tests have been performed in rough sea for two wave lengths at Fn ranging from 0.79 to 1.46. The measured pressures have been analysed in time and in frequency domain. The pressure distribution along a rectangular panel of the hull bottom has been identified. The comparison of measured values and those ones provided by Classification Societies has been performed and pressure results have been used to investigate the interactions between the fluid and the craft structure. The elastic behaviour of different bottom panels is analysed, and the scantling of a typical bottom panel, made from four materials, have been calculated, in order to investigate the structural dynamic behaviour.

This paper presents the results obtained by MArine HYdrodynamics Research Group of Department of Industrial Engineering (DII) at University of Naples regarding design and development of a zero emission craft for service in Mediterranean coastal Marine Protected Areas (MPA).

The paper focuses on the analysis of experimental seakeeping data in irregular head sea relative to constant deadrise and warped model representative of current design trends for planing hull forms. Tests have been performed at four volumetric Froude numbers ranging from 2 to 4 in one sea state. Due to non-linear nature of high-speed craft dynamics, measured motions and accelerations have been statistically analysed with the aim to find the best-fit distributions. Obtained results for heave and pitch confirm that Rayleigh and Cartwright distributions can be applied with good confidence for statistical analysis of heights and maxima/minima respectively. Weibull distribution was found to be the best-fit for statistical analysis of vertical acceleration maxima at CG and bow. Finally, the mean of 1/3rd highest vertical accelerations for both models have been compared with Fridsma’s data showing the covered range of velocities and sea states. The procedure for model-ship correlation is shown to make the results available in design practices.

Planing hard chine hull forms are widely used for high-speed small craft. While monohedral1 deep V forms have been commonly used for more than 25 years, recent trends are toward non-monohedral forms in which most of the hydrodynamic lift is produced by low deadrise areas in the after part of the hull. The deadrise gradually increases in the centre and forebody, allowing greater angles of incidence that are benefi cial to reduce wave impact forces and ship motions. Wetted surface also is reduced in comparison to the standard monohedral form, resulting in smaller frictional resistance. This trend has been initiated by the search for better seakeeping performances, and made possible by a general reduction in ship weight due to higher main engine power/weight ratio and lower structural weight. Resistance predictions based on Savitsky's method are commonly used, although this procedure has been developed on the hypothesis of monohedral geometry for the wetted part of the hull. The results are consequently affected by errors due to wrong assessment of both hydrodynamic lift and centre of pressure. In this paper, two procedures for the application of Savitsky's method to non-monohedral hulls are proposed. The results relative to a recently developed non-monohedral hull form are compared to those obtained by the standard Savitsky method and by towing tank tests. Furthermore, a study for the analysis of error propagation in Savitsky's long form procedure is proposed.

This paper presents an overview of the Lecco Innovation Hub project and in particular to the Sailing Yacht Lab project a 10 m length sailing yacht which aims to be a full scale measurement device in the sailing yacht research field. A description of scientific framework, measurement capabilities as well as of the principal design, building process, project management and commissioning is provided with some examples of preliminary collected data obtained during the first sea trials. Finally an overview of the ongoing project tasks and future project developments is provided including potential research and knowledge achievements for sailing yacht research field.

Discussion Paper.

One monohedral and three warped hard chine planing hull forms were designed at Department of Industrial Engineering, University of Naples. All models have the same transversal section at 0.25 L from the stern with 16.7° deadrise angle. Warped models have deadrise angle linearly varying along the hull length. In previous work the results of an extensive experimental program in calm water were presented. This paper is focused on the seakeeping assessment in regular waves. Aim of this research is the evaluation of the effect of deadrise angle variation along the hull length on seakeeping characteristics. Regular wave tests have been chosen to get better insight on motion and acceleration properties connected with warped hull forms and to provide a benchmark for CFD of planing hulls. Models with same load coefficient CΔ=0.428 were tested at three volumetric Froude numbers FrV=1.92, 2.60 and 3.25. Reported results are nondimensional responses for heave, pitch, and accelerations at 0.5L and bow. Particular emphasis was given to acceleration analysis by crest to trough method and spectral analysis of first and second harmonics. All results are commented with respect to hull form variation. Uncertainty analysis has been performed according to ITTC 2011 recommendations.

The results of experimental tests relative to resistance, seakeeping and roll decay of a warped hard chine hull form, suitable for large yacht design are reported. To better investigate the effect of hard chine, a round bilge identical model has been tested. Resistance tests have been performed at FV ranging from 0.90 to 4.14, for three different LCG. Results for resistance, sinkage and trim are given. For the most realistic condition dynamic wetted surface is determined separating pressure and whisker spray areas to allow reliable full scale powering predictions. For the same static trim condition, heave, pitch and accelerations have been measured for head sea at FV = 1.35 and 1.89 in regular waves for different /Lratios at constant wave steepness H/ = 1/50. Roll decay at five speeds and roll at zero speed were investigated. The reported data and considerations represent a reference for the implementation of hard chine hull form in the design of displacement and semidisplacement large yachts.

The sustainable design of small passenger vessels and large size pleasure craft indicates new trends: lower speed, reduced fuel consumption and better seakeeping in all range of velocities. Small amplitudes of roll motion are considered one of the most important comfort parameter. These trends call for reviewing some commonly used concepts and designer practice. Fundamental parameters as metacentric height and midsection form affect comfort as well as ship safety in counteracting way. Round bilge, due to good seakeeping characteristics and to large amount of available data from systematic series is the most common hull form choice when cruising speed implies displacement or semi displacement mode. Hard chine hull forms are generally chosen when relative speed leads to some hydrodynamic lift, although recently they have been considered for low relative speed. They allow simplified and cheaper construction and among their interesting features is higher roll damping. This appears very attractive for craft that are generally fitted with stabilizing systems and ask for the most reduced roll motions at any and zero speed. This paper presents the results of experimental tests relative to roll decay of two ship models of the same dimensions, displacement and GM values: they have the same warped bottom hull form developed at University of Naples, the first is hard chine and the second has round bilge from transom to midship. Both of them are suitable for displacement and semi-displacement craft operating at medium-low relative speed. The tests have been carried out at University of Naples towing tank, in calm water, at Fn ranging from 0.0 to 0.45. Natural roll frequencies and linear and non linear damping coefficients are reported for all tested speeds allowing a fair comparison of the roll characteristics due to the variation in hull form.

In this paper experimental methodologies developed at Politecnico di Milano Wind Tunnel in ordere to assess mega-yacht aerodynamics in terms of aerodynamic loads, comfort analysis, pollutants dilution and re-ingestion analysis using wind tunnel tests are described.

Hamburg(Germany)

The Czochralski pulling process is the most valuable and cost efficient method for producing large oriented single crystals of the group IV and III-V semiconductors. However, there have been only a small number of reported attempts to use the Czochralski process for growing the wide bandgap compound semiconductors, needed for the room temperature operated gamma-ray detectors. The main difficulty is in the low chemical stability and high vapor pressure of the group II, V and VI elements, leading to off-stoichiometric composition, and various related defects. Among the heavy metal halides, indium iodide and indium bromide present an interesting exception. InI has a high molecular disassociation energy and a low vapor pressure, allowing for Czochralski pulling. We will describe the procedures used and the results obtained by Czochralski growth and characterization of indium iodide and the related ternary compounds that appear to be quite encouraging.

Publisher Summary This chapter summarizes the results of a research program on high speed trimarans, jointly performed at Genoa, Naples, and Trieste Universities. Two geosim models of a trimaran hull equivalent to high speed vessels operating in the bay of Naples were built. Resistance tests were carried out to assess the best trim and configuration regarding the hydrodynamic resistance. Resistance and wave pattern tests were carried out separately on the main hull, on the outrigger, and on the trimaran. Due to very slender hulls the wave resistance of the considered trimaran is a low percentage of the total resistance and the wave interference phenomenon is generally beneficial to the trimaran. Preliminary seakeeping tests in regular waves show very significant differences of heave and pitch motions of the trimaran with respect to those of its main hull. The reported data seem to indicate a significant beneficial effect of the outriggers on the seakeeping performances.

Publisher Summary This chapter considers a trimaran ship equivalent to a typical high speed craft in service in the bay of Naples and carries out resistance model tests. Two vessels having different outrigger hull forms were designed on the basis of required lay-out of the limits in the main dimensions and of the available data from existing design. The investigation was carried out on a large model to verify the influence of the main hull trim and of the outrigger hull form and position on the trimaran hydrodynamic resistance. The investigation was carried out on two geosim models of a trimaran hull configuration with the goal to compare the ITTC'57 with the ITTC'78 model–ship correlations. For this last purpose a form factor of the trimaran was determined by different methods. The results show that the ITTC'57 could be preferable to ITTC'78 model–ship correlation in the higher Froude number range. At the designed high Froude numbers of the considered trimaran, the Wigley side hull form does not seem realistic. However, because of a lower total resistance, this side hull form could be adopted at lower Froude numbers.

An epidemiological survey of hepatitis B virus (HBV) infection has been carried out from 1974 up to 1978 in four laboratories, with the aim of identifying high-risk groups in the population. Radioimmunoassay procedures were used in order to detect the hepatitis B surface antigen (HBsAg) and the corresponding antibody (anti-HBs) in serum samples from over 100,000 individuals of various geographical origin (mainly from Ligury or from other areas in Northern Italy). The groups of population under monitoring included: individuals without hepatic illness just after admittance into hospitals (these groups were found to be adequately representative of the corresponding open population), groups of children and boys from the open school population, individuals living in various communities (foundling hospital, children college, recruits, institutionalized old people, subnormal individuals and their assistance staff), non-assistance working categories (workers from metallurgical and chemical industries, shipped seamen), hospital assistance personnel, dialyzed and transplanted renal patients, blood donors. The results obtained showed a considerable variability of HBV infections among the examined groups of population. In particular, the frequency of HBsAg and/or anti-HBs detection appeared to be significantly affected by each of the following epidemiological parameters: geographical area, sex, age, pregnancy, life in communities and contacts with hepatitis patients, mental deficiency, non-assistance working activities, assistance activity in the hospital environment, hemodialysis and transplants, selection of population groups by HBsAg screening.

The authors have performed a longitudinal study of 118 children affected with B virus chronic hepatitis. Our first observation revealed 92 children with HBeAg positive (26 CPH, 66 CAH), 22 children with anti HBe positive (6CPH, 15 CAH, 1 cirrhosis), 4 children (CAH) with e/anti-e negative. A correlation between the severity of clinical forms and the behaviour of the e/anti-e system was not observed. Seroconversion was observed during the follow up period in 37 of 92 subjects in an average time of 59.83 +/- 32 months, time rather prolonged in patients under immunosuppressive therapy. To compare the clinical progress and the evolution of CPH and CAH respectively, always with regard to the e/anti-e system, statistically significant differences did not result. Only anti HBe positive recovered subjects, inclusive of seroconverted patients and those anti HBe from the first observation, showed significant results to the statistical analysis. Still, seroconversion corresponds frequently to a stable improvement of hepatitis. On the contrary evolution into cirrhosis was observed in 5 patients that had anti HBe antibodies.

In this paper the results of experimental tests relative to resistance, seakeeping and roll decay of a warped hard chine hull form, suitable for large yacht design are reported. All tests have been carried out at University of Naples, using a scale model of 2.00 m LOA. Resistance tests are performed at FV ranging from 0.90 to 4.14, for three different CG longitudinal positions and results for resistance, sinkage and trim are given. For the most realistic condition dynamic wetted surface is determined separating pressure and whisker spray areas to allow reliable full scale powering predictions. For the same static trim condition, heave, pitch and accelerations have been measured for head sea at FV = 1.35 and 1.89 in regular waves for different L/ratios at constant wave steepness H/ = 1/50. At zero speed roll decay and roll in beam seas were investigated. Results of seakeeping tests are given in standard RAO form.

Presidente del Comitato Organizzatore del FAST 2003 ed Editor dei Proceedings: Prof.Pasquale Cassella

Southampton ( U.K.)