METODO INNOVATIVO PER LA DIAGNOSTICA DI CUSCINETTI VOLVENTI PER TRASMISSIONI AERONAUTICHE A INGRANAGGI.

Il lavoro di Tesi riassunto nella presente relazione è principalmente rivolto allo studio e alla analisi dei possibili danneggiamenti legati al funzionamento dei cuscinetti volventi, nelle loro reali condizioni di esercizio. Lo studio delle vibrazioni connesse al danneggiamento e i test sperimentali su banco prova ingranaggi, hanno consentito la messa a punto di una procedura diagnostica innovativa volta alla rilevazione della incipienza del danno sulle piste dei cuscinetti volventi. Un nuovo metodo di filtraggio consente di separare le componenti vibratorie dovute all’ingranamento, dalle componenti vibratorie legate al funzionamento dei cuscinetti

Progettazione di Sistemi per il Monitoraggio di Trasmissioni Meccaniche ad Elevate Prestazioni

La presente relazione ha lo scopo di sintetizzare il lavoro svolto nell’ambito del Dottorato di Ricerca in Ingegneria Meccanica presso la scuola Leonardo Da Vinci del Dipartimento di Ingegneria Meccanica, Nucleare e della Produzione (DIMNP) dell’Università di Pisa. Il lavoro nasce con la volontà di approfondire, da un punto di vista teorico e sperimentale, le problematiche connesse alla progettazione di sistemi avanzati per la diagnostica ed il monitoraggio da applicare alle trasmissioni meccaniche operanti in condizioni severe di velocità e carico. Le campagne sperimentali seguite dal DIMNP, in collaborazione con alcune tra le più importanti aziende del panorama industriale italiano, hanno sempre fornito occasioni di approfondimento teorico oltre che la preziosa possibilità di provare su banco i sistemi di monitoraggio progettati e realizzati. In particolare la campagna sperimentale sul danneggiamento da scuffing per ingranaggi, nata da una collaborazione tra il DIMNP, la AMTesting e Avio Propulsione Aerospaziale, ha permesso di investigare i fenomeni di innesco del danneggiamento sugli ingranaggi e la loro previsione, sia attraverso modelli previsionali del rischio, che attraverso sistemi per il monitoraggio delle reali condizioni di funzionamento delle trasmissioni. Da tale attività sono nate e si sono sviluppate importanti riflessioni sui legami che intercorrono tra l’innesco del danneggiamento, la dinamica connessa al funzionamento degli ingranaggi ed il comportamento vibratorio delle macchine su cui questi funzionano. Tali riflessioni si sono infine concretizzate nella progettazione e nella realizzazione di un sistema di monitoraggio in grado di rilevare le temperature e le deformazioni dei denti di ingranaggi durante l’esercizio, con la possibilità di attribuire alcuni danneggiamenti imprevisti, al funzionamento della trasmissioni in condizioni prossime alla risonanza. Una attività sperimentale di carattere più squisitamente diagnostico, seguita dal DIMNP in collaborazione con il Dipartimento di Matematica Applicata dell’Università di Pisa, ha consentito di rivolgere l’attività di ricerca verso un differente componente delle trasmissioni meccaniche: il cuscinetto volvente. In quel caso gli spunti nati nell’ambito della sperimentazione hanno suggerito approfondimenti teorici, i quali hanno portato alla formalizzazione di un metodo diagnostico innovativo per la identificazione del danneggiamento sui cuscinetti volventi, inseriti in trasmissioni meccaniche multi-mesh. La metodologia diagnostica è stata inoltre provata su banco in diverse condizioni di funzionamento, mostrando risultati di considerevole interesse scientifico. Una più recente collaborazione tra il DIMNP, General Electric Oil & Gas e la AMTesting, ha infine dato occasione di investigare il comportamento, in condizioni statiche e dinamiche, di un terzo componente estensivamente usato nelle trasmissioni meccaniche, soprattutto quelle operanti ad elevate velocità: il cuscinetto fluidodinamico. L’attività di ricerca ha avuto sin dall’inizio una vocazione teorica e sperimentale, spaziando dalla focalizzazione dei modelli numerici più largamente utilizzati per la previsione delle prestazioni dei cuscinetti, fino all’approfondimento sui modelli teorici di riferimento per la caratterizzazione sperimentale del loro comportamento, e la verifica su banco di tali modelli. Da tale attività è nata la partecipazione ad una campagna sperimentale di monitoraggio del comportamento di cuscinetti fluidodinamici a pattini oscillanti, svolta presso il Turbomachinery Laboratory della Texas A&M University, con utilizzo di una specifica attrezzatura di prova. Anche per tali motivi, la presente relazione è suddivisa in tre parti fondamentali, ognuna delle quali dedicata alle attività di ricerca legate ai sistemi di monitoraggio dei tre fondamentali componenti delle trasmissioni meccaniche: gli ingranaggi, i cuscinetti volventi, i cuscinetti fluidodinamici. In ognuna delle tre parti verranno sempre presi in considerazione sia le attività teoriche legate alla progettazione dei sistemi di diagnostica e monitoraggio, sia le attività sperimentali, con descrizione delle attrezzature di prova sulle quali tali sistemi hanno sempre avuto una verifica di carattere sperimentale

Self-consistent modelling of a liquid metal box-type divertor with application to the Divertor Tokamak Test (DTT) facility: Li vs. Sn

In the present work a model for a liquid metal (LM) box-type divertor is presented, aimed at including the most relevant aspects of its rich physics, as well as some engineering elements. Given the upstream plasma conditions and for a fixed divertor geometry, the model self-consistently evaluates the plasma heat and particle flux on the LM surface, the thermodynamic state of the metal (liquid and vapor) in the divertor boxes and the temperature distribution in the solid walls. The model is then applied to the Divertor Tokamak Test (DTT) facility, which is currently being designed in Italy, comparing Li and Sn as possible LM choices, in terms of operating temperatures and of metal vapor flux from the divertor box system towards the main plasma chamber

SOLPS-ITER simulations of a CPS-based liquid metal divertor for the EU DEMO: Li vs. Sn

In this work, we study the effect of installing a liquid metal divertor (LMD) using a capillary-porous structure in the EU DEMO tokamak within the same envelope of the baseline solid divertor. We used the SOLPS-ITER code to model the Scrape-Off Layer (SOL) plasma and neutrals, coupled to a target thermal model to enable the self-consistent calculation of the LM target erosion rate, and adopting a fluid neutral model for the sake of simplicity. First calculations considering only D and Li (or Sn) showed a significant reduction of the steady state target heat load with respect to simulations considering only D, thanks to vapor shielding. Nevertheless, the computed peak target heat flux (~31 MW/m2 and ~44 MW/m2 for Li and Sn, respectively) was still larger than/borderline to the power handling limit of the LMD concepts considered. Moreover, the impurity concentration in the pedestal - a proxy for the core plasma dilution/contamination - was computed to be above/close to tolerability limits suggested by previous COREDIV calculations. These results indicate that the operational window of an LMD for the EU DEMO, without any additional impurity seeding, might be too narrow, if it exists, and that Sn looks more promising than Li. A second set of calculations was then performed simulating Ar seeding in the SOL, to further reduce the target heat load, and consequently the metal erosion rate. It was found that the mitigation of the plasma heat load due to Ar radiation in the SOL effectively replaces the radiation associated to vapor shielding in front of the target, thus allowing to operate the LMD in a regime of low target erosion. The resulting operational window was found to be significantly wider, both in terms of tolerable peak target heat flux and of acceptable core plasma contamination

Health literacy in Mediterranean general population

INTRODUCTION Health literacy refers to "the ability to obtain, process, and understand basic health information and access health services in order to make informed choices." In essence, being able to acquire, understand, and use information for one's own health. METHODS Observational study through the administration of a face-to-face questionnaire conducted between July and September 2020 on 260 individuals residing between Calabria and Sicily, aged between 18 and 89 years. Questions related to education, lifestyle (alcohol, smoking, and physical activity). Multiple-choice questions to assess health literacy and conceptual skills, ability to find information on health topics and services, use of preventive medicine especially vaccinations, and ability to make decisions about one's own health. RESULTS Of 260, 43% were male and 57% female. The most represented age group is between 50 and 59 years. Forty-eight percent of respondents had a high school diploma. 39% smoke and 32% habitually consume alcoholic beverages; only 40% engage in physical activity. Ten percent had a low level of health literacy, average 55%, adequate 35%. CONCLUSIONS Given the importance of adequate HL on health choices and on individual and public wellbeing, it is essential to expand the knowledge of the individual, through public and private information campaigns and with an increasing involvement of family physicians, who are fundamental in training and informing their patients

Health education intervention to improve vaccination knowledge and attitudes in a cohort of Obstetrics students.

Introduction. To improve the vaccination coverage in pregnant women it is important to increase their knowledge of vaccines and related preventable diseases. Midwifes can play an important role because they are often the first contact for woman during her pregnancy. This study aimed to explore the vaccination knowledge and attitudes in a cohort of Obstetrics students in Italy and improve their knowledge through an informative health education intervention. Methods. The study consisted in the administration of a first questionnaire followed by a health education intervention concerning all aspects of vaccinations. Then, a second questionnaire to evaluate the efficacy of the educational program was administered. Results. From the pre-intervention questionnaire resulted that almost the whole sample (97.1%) were favorable to vaccines in general. Moreover, 65.7% of the participants declared a sufficient level of vaccination knowledge but 62.9% found herself unprepared to answer questions and provide information about vaccinations. Concerning the answers about vaccination in pregnancy, the correct answers went from 17.1%, to 68.6% respectively before and after educational intervention. The training intervention obtained a total consensus (100%). The most part of the students (85.7%) declared that the received information changed some of their beliefs and the entire sample (100%) stated that it improved their preparation. Conclusions. Our results revealed some critical issues in the preparation of midwifes about vaccinations and confirm the necessity to carry out health intervention campaigns to these health professionals that, for the role they play, they must necessarily be well prepared

Measurement of the thermal expansion coefficient of an Al-Mg alloy at ultra-low temperatures

We describe a result coming from an experiment based on an Al-Mg alloy (~ 5% Mg) suspended bar hit by an electron beam and operated above and below the termperature of transition from superconducting to normal state of the material. The amplitude of the bar first longitudinal mode of oscillation, excited by the beam interacting with the bulk, and the energy deposited by the beam in the bar are the quantities measured by the experiment. These quantities, inserted in the equations describing the mechanism of the mode excitation and complemented by an independent measurement of the specific heat, allow us to determine the linear expansion coefficient of the material.Comment: 13 pages, 4 figure

Brief comments on Jackiw-Teitelboim gravity coupled to Liouville theory

Jackiw-Teitelboim gravity with non-vanishing cosmological constant coupled to Liouville theory is considered as a non-critical string on $d$ dimensional flat spacetime. It is discussed how the presence of cosmological constant yields additional constraints on the parameter space of the theory, even when the conformal anomaly is independent of the cosmological constant. Such constraints agree with the necessary conditions for the tachyon field to be a primary --prelogarithmic-- operator of the worldsheet conformal field theory. Thus, the linearized tachyon field equation allows to impose the diagonal condition for the interaction term. We analyze the neutralization of the Liouville mode induced by the coupling to the Jackiw-Teitelboim Lagrangian. The free field prescription leads to obtain explicit expressions for three-point correlation functions for the case of vanishing cosmological constant in terms of a product of Shapiro-Virasoro integrals. This is a consequence of the mentioned neutralization effect.Comment: 14 pages, no figures. v2 References added. To be published in Classical and Quantum Gravity. v3 typos correcte

The future search for low-frequency axions and new physics with the FLASH resonant cavity experiment at Frascati National Laboratories

We present a proposal for a new experiment, the FINUDA magnet for Light Axion SearcH (FLASH), a large resonant-cavity haloscope in a high static magnetic field which is planned to probe new physics in the form of dark matter (DM) axions, scalar fields, chameleons, hidden photons, as well as high frequency gravitational waves (GWs). Concerning the QCD axion, FLASH will search for these particles as the DM in the mass range (0.49-1.49) ueV, thus filling the mass gap between the ranges covered by other planned searches. A dedicated Microstrip SQUID operating at ultra-cryogenic temperatures will amplify the signal. The frequency range accessible overlaps with the Very High Frequency (VHF) range of the radio wave spectrum and allows for a search in GWs in the frequency range (100-300) MHz. The experiment will make use of the cryogenic plant and magnet of the FINUDA experiment at INFN Frascati National Laboratories near Rome (Italy); the operations needed to restore the functionalities of the apparatus are currently underway. We present the setup of the experiment and the sensitivity forecasts for the detection of axions, scalar fields, chameleons, hidden photons, and GWs