Domenico Sguerso, Annalisa Azzola, Carlo Nike Bianchi, Bianca Federici, Sara Gagliolo, Carla Morri, Monica Montefalcone
3D photogrammetric surveys on coral reefs in the Maldives

The global increase in seawater temperature is causing irreparable damages to coral reefs all over the world. Frequency of coral bleaching episodes and mass mortality is increasing and coral reefs have not enough time to recover after these impacts. The present study concerns this phenomenon in the context of the Maldives. In this scenario, monitoring activities are very important to check the health of coral reefs, and the adoption of specific parameters such as reef rugosity and accretion of corals provides important measures of the ability of reefs to recover after bleaching. Moreover, the use of photogrammetry allows speeding up the on-site measurements, enlarging the scale and the reliability. The input data are the images traditionally taken by operators for visual analysis, paying attention to the achievement of photogrammetric principles.

E. Balestrieri, F. Bonavolontà, E. Caputo, P. Daponte, E. Della Volpe, A. Tedesco
The MetroSea Student Contest: An Amazing Educational Experience at 2019 IMEKO TC-19 International Workshop on Metrology for the Sea

The paper presents a new educational experience capable of merging different approaches such as project-based learning, inquiry-based learning and Science Technology Engineering and Mathematics (STEM) into a students competition to be held at the International Workshop on Metrology for the Sea. The contest is focused on the pollution control and removal by means of autonomous boats capable of achieving and reaching the position of floating rubbish (such as plastic). To accomplish the considered target, contest competitors have to take into account different problems, from boat assembly to autopilot implementation, from GPS positioning to navigation control. Despite of the competition results, the main goal of the contest is to motivate students to address the global challenge of sea pollution through a set of enabling technologies and soft skills. Students and teachers can therefore take advantage from an alternative solution to overcome typical drawbacks associated with traditional frontal learning practices, such as lack of motivation, insufficient practical laboratory experience, and inadequate collaborative team working practice.

Domenico Maraglino, Mouldi Ben Meftah, Francesca De Serio, Michele Mossa
Field measurements in a flow around a hydrofoil: some preliminary results

This work reports the first results of an experimental study aimed at investigating the flow field modified by a hydrofoil NACA 0012 immersed in a water current. The velocity measurements were carried out at the Hydraulic Laboratory of the DICATECh (Polytechnic University of Bari, Italy) using an ADV (Acoustic Doppler Velocimeter) and a PIV (Particle Image Velocimetry) system, in order to reconstruct the flow field and the turbulence characteristics. We obtained instantaneous and average velocity vector maps, as well as instantaneous streamlines maps, in the streamwise direction, in vertical frames located both upstream and downstream of the hydrofoil. Furthermore, the vertical velocity profiles in some selected sections were also examined. The analysis of the acquired data was also performed in the frequency domain. The principal results show that the velocity profiles obtained with the PIV and ADV are comparable and that the frequency of vortex shedding downstream of the hydrofoil is in agreement with Strouhal s theoretical relationship.

Beata Palczynska, Romuald Masnicki, Janusz Mindykowski
Harmonics detection in frequency sparse signal

The article shows the possibilities of using the compressive sensing technique to detect harmonics in a frequency sparse signal. Such features characterize signals in the ship s electrical network. A fast algorithm is presented, in which few randomly sampled projections of the input signal are used for its correct reconstruction. The ℓ1-minimization problem in the compressive signal reconstruction is resolved by means of the convex optimization method with thresholding and the additional use of the K-rank-order filter in the signal s sparse domain in order to accelerate the convergence of the solution. The preliminary results of numerical simulation confirm the effectiveness of the algorithm used but also indicate its limitations.

Romuald Masnicki, Janusz Mindykowski
Case study-based ZigBee network implementation for maritime on-board safety improvement

This paper is dedicated to some aspects of maritime on-board safety improvement. Analyzed aspects concern the measurement and control signal transmission on marine environment. The main topic faced by the paper is concentrated on case study-based ZigBee network implementation in the area of the acquisition of data from sensors and measuring transducers connected to the terminal network. The exemplary implementation of ZigBee network, elaborated in Gdynia Maritime University is related, firstly, to the configuration of a simple wireless measurement and control channel, and secondly, to wireless communication channel supported by autonomously working microprocessor measurement and control system. Finally, some concluding remarks are formulated.