Development of gripping devices based on electroadhesive forces

In a context of technological innovation, the aim of this thesis is to develop a technology that has gained interest in both scientific and industrial realms. This technology serves as a viable alternative to outdated and energy-consuming industrial systems. Electro-adhesive devices (EADs) leverage electrostatic forces for grasping objects or adhering to surfaces. The advantage of employing electrostatics lies in its adaptability to various materials without compromising the structure or chemistry of the object or surface. These benefits have led the industry to explore this technology as a replacement for costly vacuum systems and suction cups currently used for handling most products. Furthermore, the broad applicability of this technology extends to extreme environments, such as space with ultra-high vacuum conditions. Unfortunately, research in this area has yet to yield practical results for industrially effective gripper prototyping. This is primarily due to the inherent complexity of electro-adhesive technology, which operates on basic capacitive principles that does not find satisfying physical descriptions. This thesis aims to address these challenges through a series of studies, starting with the manufacturing process and testing of an EAD that has become the standard in our laboratory. It then delves into material and electrode geometry studies to enhance system performance, ultimately presenting potential industrial applications of the technology. All the presented results are encouraging, as they have yielded shear force values three times higher than those previously reported in the literature. The various applications have demonstrated the significant effectiveness of EADs as brakes or, more broadly, in exerting shear forces. This opens up the possibility of utilizing cutting-edge technologies to push the boundaries of technology to the fullest.

Insegnare l'italiano L2 per fini di studio: una proposta di letture graduate per gli studenti cinesi

Dati i problemi di comprensione linguistica riscontrati dagli studenti cinesi nel contesto accademico e la crescente necessità della didattica dell’italiano L2 per fini di studio, il presente lavoro ha come obiettivo finale la creazione di letture graduate, proposte come materiali didattici comprensibili e mirati agli studenti cinesi di italiano L2, in modo da agevolare il loro approccio ai testi impegnativi richiesti per gli studi artistico-professionali. In particolare, nei primi due capitoli si discute il ruolo significativo della distanza linguistica tra italiano e cinese nell’acquisizione della L2 da parte degli studenti cinesi e nello sviluppo della loro abilità di lettura in L2. In seguito, per capire come debba essere un input ideale per l’acquisizione linguistica a fini di studio, vengono esaminati vari approcci glottodidattici basati sull’input, e si osservano i tratti delle varietà di italiano presenti nel contesto accademico. Il lavoro procede poi con un’analisi delle specifiche caratteristiche linguistiche riscontrate in manuali universitari di storia dell’arte, utilizzando sia un approccio quantitativo che qualitativo, con l’obiettivo di avere un “panorama” delle complessità linguistiche che uno studente L2 deve affrontare nello studio. Successivamente, verrà presentata una sperimentazione di riscrittura con due gruppi, i quali sono stati sottoposti rispettivamente al testo originale e a quello riscritto secondo i criteri formulati dallo studio teorico sul confronto tipologico. I risultati ottenuti confermano sia le interferenze del cinese nella lettura in italiano, sia l’efficacia degli approcci linguistici individuati nel facilitare la comprensibilità del testo per gli studenti cinesi di livello A2-B1. Di conseguenze, viene proposto un percorso di letture graduate per gli studenti cinesi di belle arti; oltre a essere comprensibili, le letture mirano anche all’acquisizione delle varietà di italiano necessarie per lo studio accademico-professionale. L’ultima parte del lavoro è dedicata alle riflessioni teoriche e didattiche sviluppate nel corso della ricerca.

Models and methods for damage and quantitative risk assessment of Natech scenarios

Natural events are a widely recognized hazard for industrial sites where relevant quantities of hazardous substances are handled, due to the possible generation of cascading events resulting in severe technological accidents (Natech scenarios). Natural events may damage storage and process equipment containing hazardous substances, that may be released leading to major accident scenarios called Natech events. The need to assess the risk associated with Natech scenarios is growing and methodologies were developed to allow the quantification of Natech risk, considering both point sources and linear sources as pipelines. A key element of these procedures is the use of vulnerability models providing an estimation of the damage probability of equipment or pipeline segment as a result of the impact of the natural event. Therefore, the first aim of the PhD project was to outline the state of the art of vulnerability models for equipment and pipelines subject to natural events such as floods, earthquakes, and wind. Moreover, the present PhD project also aimed at the development of new vulnerability models in order to fill some gaps in literature. In particular, a vulnerability model for vertical equipment subject to wind and to flood were developed. Finally, in order to improve the calculation of Natech risk for linear sources an original methodology was developed for Natech quantitative risk assessment methodology for pipelines subject to earthquakes. Overall, the results obtained are a step forward in the quantitative risk assessment of Natech accidents. The tools developed open the way to the inclusion of new equipment in the analysis of Natech events, and the methodology for the assessment of linear risk sources as pipelines provides an important tool for a more accurate and comprehensive assessment of Natech risk.

Mechanical behaviour and durability assessment of Fibre Reinforced Cementitious Matrix (FRCM) strengthening systems.

In recent years, the seismic vulnerability of existing masonry buildings has been underscored by the destructive impacts of earthquakes. Therefore, Fibre Reinforced Cementitious Matrix (FRCM) retrofitting systems have gained prominence due to their high strength-to-weight ratio, compatibility with substrates, and potential reversibility. However, concerns linger regarding the durability of these systems when subjected to long-term environmental conditions. This doctoral dissertation addressed these concerns by studying the effects of mild temperature variations on three FRCM systems, featuring basalt, glass, and aramid fibre textiles with lime-based mortar matrices. The study subjected various specimens, including mortar triplets, bare textile specimens, FRCM coupons, and single-lap direct shear wallets, to thermal exposure. A novel approach utilizing embedded thermocouple sensors facilitated efficient monitoring and active control of the conditioning process. A shift in the failure modes was obtained in the single lap-direct shear tests, alongside a significant impact on tensile capacity for both textiles and FRCM coupons. Subsequently, bond tests results were used to indirectly calibrate an analytical approach based on mode-II fracture mechanics. A comparison between Cohesive Material Law (CML) functions at various temperatures was conducted for each of the three systems, demonstrating a good agreement between the analytical model and experimental curves. Furthermore, the durability in alkaline environment of two additional FRCM systems, characterized by basalt and glass fibre textiles with lime-based mortars, was studied through an extensive experimental campaign. Tests conducted on single yarn and textile specimens after exposure at different durations and temperatures revealed a significant impact on tensile capacity. Additionally, FRCM coupons manufactured with conditioned textile were tested to understand the influence of aged textile and curing environment on the final tensile behavior. These results contributed significantly to the existing knowledge on FRCM systems and could be used to develop a standardized alkaline testing protocol, still lacking in the scientific literature.

Predizione degli outcome del rivolgimento per manovre esterne nelle gravidanze con presentazione podalica del feto con l'utilizzo dell'angolo di progressione della parte presentata

Introduzione: La presentazione podalica complica il 3-4% delle gravidanze singole a termine. Sebbene il parto vaginale sia possibile, gli studi in letteratura hanno riportato un aumento del rischio di mortalità e morbilità fetale. Di conseguenza nel mondo il numero di tagli cesarei eseguiti per presentazione podalica è alto. Il rivolgimento per manovre esterne (RME) è una procedura ostetrica sicura che permette il passaggio del feto dalla presentazione podalica a quella cefalica, riducendo il numero dei tagli cesarei. L’angolo di progressione della parte presentata (AoP) è un parametro ecografico descritto in letteratura per la valutazione della progressione della parte presentata attraverso il canale del parto ed è stato recentemente studiato nelle gravidanze con presentazione podalica del feto. Obiettivi: L’obiettivo primario è valutare la correlazione tra l’AoP e il successo del RME. L’obiettivo secondario è verificare se esiste correlazione tra parametri anamnestici ed ecografici e la riuscita del RME. Materiali e metodi: È stato condotto uno studio osservazione prospettico monocentrico, sono state reclutate previo consenso informato 54 pazienti afferenti presso l’Ospedale Maggiore di Bologna con gravidanza singola dopo le 36 settimane e feto in presentazione podalica tra gennaio 2020 e giugno 2023. Risultati: La percentuale di RME riusciti è stata del 48,2%, il 53,7% delle donne ha partorito mediante taglio cesareo. Non abbiamo trovato una correlazione tra AoP e successo del rivolgimento. Tra le altre variabili analizzate l’unica correlata al successo del RME è la quantità di liquido amniotico Conclusioni: Non abbiamo trovato una correlazione tra AOP e successo del RME. Come descritto in letteratura l’unico parametro ecografico che è risultato associato al successo del RME è la quantità di liquido amniotico. Dato il disegno dello studio e la scarsa numerosità del campione sono necessari ulteriori studi per confermare i risultati.

Data-driven multivariate flood hazard modeling

The present Dissertation shows how recent statistical analysis tools and open datasets can be exploited to improve modelling accuracy in two distinct yet interconnected domains of flood hazard (FH) assessment. In the first Part, unsupervised artificial neural networks are employed as regional models for sub-daily rainfall extremes. The models aim to learn a robust relation to estimate locally the parameters of Gumbel distributions of extreme rainfall depths for any sub-daily duration (1-24h). The predictions depend on twenty morphoclimatic descriptors. A large study area in north-central Italy is adopted, where 2238 annual maximum series are available. Validation is performed over an independent set of 100 gauges. Our results show that multivariate ANNs may remarkably improve the estimation of percentiles relative to the benchmark approach from the literature, where Gumbel parameters depend on mean annual precipitation. Finally, we show that the very nature of the proposed ANN models makes them suitable for interpolating predicted sub-daily rainfall quantiles across space and time-aggregation intervals. In the second Part, decision trees are used to combine a selected blend of input geomorphic descriptors for predicting FH. Relative to existing DEM-based approaches, this method is innovative, as it relies on the combination of three characteristics: (1) simple multivariate models, (2) a set of exclusively DEM-based descriptors as input, and (3) an existing FH map as reference information. First, the methods are applied to northern Italy, represented with the MERIT DEM (∼90m resolution), and second, to the whole of Italy, represented with the EU-DEM (25m resolution). The results show that multivariate approaches may (a) significantly enhance flood-prone areas delineation relative to a selected univariate one, (b) provide accurate predictions of expected inundation depths, (c) produce encouraging results in extrapolation, (d) complete the information of imperfect reference maps, and (e) conveniently convert binary maps into continuous representation of FH.

Decoding complex flow phenomena via Dynamic Mode Decomposition

In this thesis, the viability of the Dynamic Mode Decomposition (DMD) as a technique to analyze and model complex dynamic real-world systems is presented. This method derives, directly from data, computationally efficient reduced-order models (ROMs) which can replace too onerous or unavailable high-fidelity physics-based models. Optimizations and extensions to the standard implementation of the methodology are proposed, investigating diverse case studies related to the decoding of complex flow phenomena. The flexibility of this data-driven technique allows its application to high-fidelity fluid dynamics simulations, as well as time series of real systems observations. The resulting ROMs are tested against two tasks: (i) reduction of the storage requirements of high-fidelity simulations or observations; (ii) interpolation and extrapolation of missing data. The capabilities of DMD can also be exploited to alleviate the cost of onerous studies that require many simulations, such as uncertainty quantification analysis, especially when dealing with complex high-dimensional systems. In this context, a novel approach to address parameter variability issues when modeling systems with space and time-variant response is proposed. Specifically, DMD is merged with another model-reduction technique, namely the Polynomial Chaos Expansion, for uncertainty quantification purposes. Useful guidelines for DMD deployment result from the study, together with the demonstration of its potential to ease diagnosis and scenario analysis when complex flow processes are involved.