Wireless Sensor Node for Surface Seawater Density Measurements

An electronic meter to measure surface seawater density is presented. It is based on the measurement of the difference in displacements of a surface level probe and a weighted float, which according to Archimedes’ law depends on the density of the water. The displacements are simultaneously measured using a high-accuracy magnetostrictive sensor, to which a custom electronic board provides a wireless connection and power supply so that it can become part of a wireless sensor network. The electronics are designed so that different kinds of wireless networks can be used, by simply changing the wireless module and the relevant firmware of the microcontroller. Lastly, laboratory and at-sea tests are presented and discussed in order to highlight the functionality and the performance of a prototype of the wireless density meter node in a Bluetooth radio network. The experimental results show a good agreement of the values of the calculated density compared to reference hydrometer readings

Sistemi di Gestione di Batterie al Litio per la Trazione Elettrica

La presente tesi tratta lo sviluppo di un sistema di gestione di batterie al litio per applicazioni di potenza, quale la trazione elettrica. Il sistema elettronico è stato progettato in tutte le sue parti e ne sono stati realizzati alcuni prototipi. I risultati di test sperimentali effettuati su tali prototipi sono presentati e confrontati con lo stato dell'arte. Sono state trattate inoltre tecniche di stima dello stato di carica per celle al litio e sistemi di equalizzazione attiva della carica ad alta efficienza

A New and Accurate System for Measuring Cruising Yacht Freeboards With Magnetostrictive Sensors

Knowing the freeboard levels of a yacht is crucial for boat builders and hull designers because it allows them to easily obtain precise information about the ship displacement, as well as about its trim. This paper describes a system that automatically performs the freeboard acquisition (substituting the rudimental and inaccurate manual reading currently used) with a great improvement of the measurement automation and accuracy. It consists of a wireless sensor network, the nodes of which are three magnetostrictive water level sensors, an inclinometer, and a personal-computer-based central unit. The major error sources in the measurements have been investigated and controlled to be below a desired accuracy by compensating for temperature and water-density variations. In fact, one node of the network is equipped with an additional level meter that allows the direct and automatic measurement of the water density, i.e., a fundamental parameter to calculate the boat displacement. The experimental results show the functionality of the system and also its great potential in extracting additional information for yacht characterization by means of postprocessing the acquired data