Numerical and experimental analysis of the bi-stable state for frictional continuous system

Unstable friction-induced vibrations are considered an annoying problem in several fields of engineering. Although several theoretical analyses have suggested that friction-excited dynamical systems may experience sub-critical bifurcations, and show multiple coexisting stable solutions, these phenomena need to be proved experimentally and on continuous systems. The present work aims to partially fill this gap. The dynamical response of a continuous system subjected to frictional excitation is investigated. The frictional system is constituted of a 3D printed oscillator, obtained by additive manufacturing that slides against a disc rotating at a prescribed velocity. Both a finite element model and an experimental setup has been developed. It is shown both numerically and experimentally that in a certain range of the imposed sliding velocity the oscillator has two stable states, i.e. steady sliding and stick–slip oscillations. Furthermore, it is possible to jump from one state to the other by introducing an external perturbation. A parametric analysis is also presented, with respect to the main parameters influencing the nonlinear dynamic response, to determine the interval of sliding velocity where the oscillator presents the two stable solutions, i.e. steady sliding and stick–slip limit cycle

Sulfur content in foods consumed in an Italian population and impact of diet quality on sulfur intake

Sulfur is an essential nutrient but data about its intake are scarce. We aimed to measure sulfur content in food samples and assess its habitual intake in relation to adherence to healthy dietary patterns in 719 Italian adults. Using a food frequency questionnaire, we estimated overall sulfur intake, and its relation with adherence to healthy dietary patterns. The highest sulfur content was found in preserved/canned fish (3.0 g/kg), seafood (2.8 g/kg), white meat (2.8 g/kg) and dairy products, particularly aged cheeses (2.1 g/kg) and lowest in fresh fruit (87 mg/kg), oils and fats (157 mg/kg), and beverages (141 mg/kg), with the exception of onion and garlic (1.3 g/kg). The mean sulfur intake in the study population was 1.1 g/day, slightly higher in men than women. The foods contributing most to sulfur intake were meat (29%) and cereals (19%), with also substantial contribution (>10%) from beverages and dairy products. Adherence to dietary patterns had little influence on sulfur intake, except for adherence to MIND diet positively and linearly associated with sulfur intake. Our study provides an updated overview of sulfur content in foods composing the Italian diet, as well as of sulfur intake in an Italian community of Northern Italy

System Level Analysis of Millimetre-wave GaN-based MIMO Radar for Detection of Micro Unmanned Aerial Vehicles

The detection of Unmanned Aerial Vehicles (UAVs) of micro/nano dimensions, is becoming a hot topic, due to their large diffusion, and represents a challenging task from both the system architecture and components point of view. The Frequency Modulated Continuous Wave (FMCW) radar architecture in a Multi-Input Multi-Output configuration has been identified as the most suitable solution for this purpose, due to both its inherent short-range detection capability and compact implementation. This paper describes the operation and technology challenges inherent to the development of a millimeter-wave FMCW MIMO radar for small UAVs detection. In particular it analyzes the sub-systems specifications and the expected system performance with respect to a chip set designed and developed in GaN at 37.5 GHz applications

A novel microbiological approach to impact the aromatic composition of sour loquat beer

The growing interest in novel beer development determined the exploitation of unconventional yeasts isolated from novel ecological niches to generate unexplored sensory profiles. In recent years, there is an increasing interest in generating beers brewed with the addition of fruits. For the first time, Lachancea thermotolerans MNF105 and Saccharomyces cerevisiae MN113 isolated from manna, were tested as starter cultures to process loquat beer to improve the sensory profile. Innovatively, the yeast species L. thermotolerans was investigated for the production of sour fruit beer. Sour fruit beers produced with L. thermotolerans MNF105 were more balanced than the respective control, especially in terms of perceived acidity during sensory analysis. This could be due to the lower lactic acid production (0.49 g/L) compared to the respective control (1.74 g/L). The overall organoleptic investigation showed a preference for S. cerevisiae MN113 (TF1) isolated from manna. Experimental trials conducted with the selected strains demonstrated the absence of off-odour and off-flavour and improved aroma perception. Aldehydes and alcohols were the most abundant compounds emitted from the beers. S. cerevisiae MN113 and L. thermotolerans MNF105, manna related yeasts, showed great technological properties, representing promising starters for the production of fruit beer and sour fruit beer

The marine activities performed within the TOMO-ETNA experiment

The TOMO-ETNA experiment was planned in order to obtain a detailed geological and structural model of the continental and oceanic crust beneath Mt. Etna volcano and northeastern Sicily up to the Aeolian Islands (southern Italy), by integrating data from active and passive refraction and reflection seismic methodologies, magnetic and gravity surveys. This paper focuses on the marine activities performed within the experiment, which have been carried out in the Ionian and Tyrrhenian Seas, during three multidisciplinary oceanographic cruises, involving three research vessels (\u201cSarmiento de Gamboa\u201d, \u201cGalatea\u201d and \u201cAegaeo\u201d) belonging to different countries and institutions. During the offshore surveys about 9700 air-gun shots were produced to achieve a high-resolution seismic tomography through the wide-angle seismic refraction method, covering a total of nearly 2650 km of shooting tracks. To register ground motion, 27 ocean bottom seismometers were deployed, extending the inland seismic permanent network of the Istituto Nazionale di Geofisica e Vulcanologia (INGV) and a temporary network installed for the experiment. A total of 1410 km of multi-channel seismic reflection profiles were acquired to image the subsurface of the area and to achieve a 2D velocity model for each profile. Multibeam sonar and sub bottom profiler data were also collected. Moreover, a total of 2020 km of magnetic and 680 km of gravity track lines were acquired to compile magnetic and gravity anomaly maps offshore Mt. Etna volcano. Here, high-resolution images of the seafloor, as well as sediment and rock samples, were also collected using a remotely operated vehicle

“Messina 1908-2008”: Progetto di ricerca integrato per l’area Calabro - Peloritana. L’esperimento di sismica passiva

Il 28 dicembre 1908 un forte terremoto colpì duramente le città di Messina e di Regg io Calabria e molteplici centri abitati limitrofi. L’evento sismico di Mw=7.1 generò un maremoto e causò circa 100.000 morti. Durante il 2008 numerose sono state le iniziative per rievocare tale importante terremoto che è ricordato nella storia come il più forte avvenuto in Italia. Tra le iniziative promosse dall’Istituto Nazionale di Geofisica e Vulcanologia vi è il progetto di ricerca “Messina 1908-2008” le cui finalità sono far convergere i dati sismici e geodetici g ià a disposizione dei singoli gruppi di ricerca in un’unica banca dati e nel contempo promuoverne l’acquisizione di nuovi. In questo rapporto è descritto l’esperimento di sismica passiva integrato mare-terra iniziato ad ottobre 2007 e ter minato nel gennaio 2010 avente l’obiettivo di acquisire nuovi dati di alta qualità e dettaglio per ottenere una migliore definizione della microsismicità locale. Ciò consentirà di raggiungere una migliore comprensione di come inter ag iscano il processo di subduzione e le dinamiche superficiali nell’area dell’arco Calabro Peloritano ed in particolare nello stretto di Messina

Development of a low-cost seismic station based on MEMS technology

L’impatto di un forte terremoto su una comunità urbana può essere ridotto con una azione tempestiva e ben pianificata da parte degli organi di Protezione Civile preposti. In tale prospettiva è di fondamentale importanza che gli organi preposti alla sorveglianza sismica del territorio nazionale si dotino di strumenti di osservazione puntuale in grado di fornire nell’immediato terremoto informazioni utilissime per la gestione ottimale delle emergenze. Ciò può essere fatto oggi mediante la realizzazione reti sismiche urbane, con funzionamento in tempo reale (OSU Osservatori Sismici Urbani), in grado di fornire in maniera tempestiva ai centri per la gestione delle emergenze, la distribuzione dell'intensità dello scuotimento a seguito di un terremoto. Le mappe di scuotimento potrebbero consentire agli organi preposti, un’ottimale gestione delle priorità e la ripartizione delle risorse in modo da ottenere una significativa riduzione del numero di vittime a seguito di un forte terremoto. Le verifiche del grado di danneggiamento e di agibilità degli edifici potrebbero così essere effettuate secondo una logica prioritaria sulla base dei massimi scuotimenti misurati dalla rete sismica urbana. La realizzazione di OSU per le finalità su preposte è l’obiettivo principale del progetto MEMS finanziato dal MIUR nell’ambito del programma SIR (Scientific Independence of young Researchers). La prima sfida affrontata nell’ambito del progetto MEMS è stata la progettazione e sviluppo di una stazione accelerometrica idonea agli scopi del progetto. Il presente lavoro ha lo scopo di descrivere nel dettaglio, la stazione accelerometrica basata su tecnologia MEMS (Micro ElectroMechanical Systems), implementata nell’abito dell’omonimo progetto. Ciò che stato realizzato è una stazione accelerometrica dalle ottime performance, estremamente versatile e a bassissimo costo.The impact of a strong earthqauke onto an urban community can be reduced taking timely actions managed by the authority in charge for the civil protection. In this view, it is of fundamental importance that the authority in charge for the seismic surveillance is provided with the appropriate monitoring tools able to give the most useful information for the best emergency management in the immediate post-event. Today this goal can be reached realizing urban-scale, real-time seismic monitoring networks (Osservatori Sismici Urbani, OSU, in Italian). The real-time OSU networks are able to promptly provide information to the emergency authority about the ground shaking at each node after an earthquake. Maps showing the spatial distribution of the ground shaking could help in the optimization of the priorities and a good management of the rescue resources in order to reduce the number of victims. Also the assessment of the damage of the buildings could be carried out according to the logic of priority given by the shakings measured by the OSU. The realisation of OSUs is the main objective of the MEMS project. This project is funded by the MIUR under the SIR program (Scientific Independence of young Researchers). The first challenge of the MEMS project was the design and the development of a devoted accelerometric stations. This work illustrates in detail the accelerometric station based on MEMS technology (Micro Electro-Mechanical Systems). The final product is a low-cost accelerometric station with high performance and great versatility

“Messina 1908-2008”: Progetto di ricerca integrato per l’area Calabro - Peloritana. L’esperimento di sismica passiva

Il 28 dicembre 1908 un forte terremoto colpì duramente le città di Messina e di Regg io Calabria e molteplici centri abitati limitrofi. L’evento sismico di Mw=7.1 generò un maremoto e causò circa 100.000 morti. Durante il 2008 numerose sono state le iniziative per rievocare tale importante terremoto che è ricordato nella storia come il più forte avvenuto in Italia. Tra le iniziative promosse dall’Istituto Nazionale di Geofisica e Vulcanologia vi è il progetto di ricerca “Messina 1908-2008” le cui finalità sono far convergere i dati sismici e geodetici g ià a disposizione dei singoli gruppi di ricerca in un’unica banca dati e nel contempo promuoverne l’acquisizione di nuovi. In questo rapporto è descritto l’esperimento di sismica passiva integrato mare-terra iniziato ad ottobre 2007 e ter minato nel gennaio 2010 avente l’obiettivo di acquisire nuovi dati di alta qualità e dettaglio per ottenere una migliore definizione della microsismicità locale. Ciò consentirà di raggiungere una migliore comprensione di come inter ag iscano il processo di subduzione e le dinamiche superficiali nell’area dell’arco Calabro Peloritano ed in particolare nello stretto di Messina.Istituto Nazionale di Geofisica e VulcanologiaPublished1.1. TTC - Monitoraggio sismico del territorio nazionaleope