Studio delle interazioni ruota-rotaia ai fini della sicurezza dell’esercizio e della manutenzione sviluppo di un sistema di misura sperimentale per il monitoraggio dei carichi trasversali

Il presente lavoro, esaminando la situazione del settore ferroviario europeo in relazione alla sicurezza della circolazione ed alla manutenzione dei veicoli, affronta lo studio della misura delle forze di contatto, su base teorica e sperimentale, ai fini dello sviluppo di un sistema di misura sperimentale per il monitoraggio dei carichi trasversali (Y), lato infrastruttura. Attraverso una prima convenzione di ricerca con Rete Ferroviaria Italiana (RFI), è stato effettuato uno studio di fattibilità preliminare, confrontando tra loro due metodologie di misura differenti; successivamente la ricerca è proseguita a livello accademico approfondendo le potenzialità applicative di uno dei due metodi precedentemente analizzati. Infine, attraverso una seconda convenzione di ricerca, sempre con Rete Ferroviaria Italiana (RFI), si è sviluppato il sistema di misura a livello prototipale conducendo ulteriori prove sperimentali di laboratorio ed installando l’apparato direttamente in linea durante il normale esercizio

Usefulness of Linear Mixed-Effects Models to Assess the Relationship between Objective and Subjective Internal Load in Team Sports

Internal load can be objectively measured by heart rate-based models, such as Edwards' summated heart rate zones, or subjectively by session rating of perceived exertion. The relationship between internal loads assessed via heart rate-based models and session rating of perceived exertion is usually studied through simple correlations, although the Linear Mixed Model could represent a more appropriate statistical procedure to deal with intrasubject variability. This study aimed to compare conventional correlations and the Linear Mixed Model to assess the relationships between objective and subjective measures of internal load in team sports. Thirteen male youth beach handball players (15.9 ± 0.3 years) were monitored (14 training sessions; 7 official matches). Correlation coefficients were used to correlate the objective and subjective internal load. The Linear Mixed Model was used to model the relationship between objective and subjective measures of internal load data by considering each player individual response as random effect. Random intercepts were used and then random slopes were added. The likelihood-ratio test was used to compare statistical models. The correlation coefficient for the overall relationship between the objective and subjective internal data was very large (r = 0.74; ρ = 0.78). The Linear Mixed Model using both random slopes and random intercepts better explained (p < 0.001) the relationship between internal load measures. Researchers are encouraged to apply the Linear Mixed Models rather than correlation to analyze internal load relationships in team sports since it allows for the consideration of the individuality of players

Structural analysis of the double-walled copper-steel cryogenic chamber of the ASTAROTH experiment

This document describes the verification process of structural performance of the double- walled copper-steel cryogenic chamber of the ASTAROTH (All Sensitive crysTal ARray with lOw THreshold) experiment and the evaluation of the stresses generated near the thermal bridge connecting the inner and outer wall. The chamber consists of an external AISI 316L stainless steel dewar and an inner double-walled OF (Oxygen Free) copper dewar connected to an AISI 316L stainless steel flanged collar. The results showed that close to the thermal bridge (copper-steel junction) the stresses slightly exceed the YS of copper at the estimated operating temperature (localised strain-hardening condition). On the other hand, the safety coefficient respect to fracture is well above one for both materials. This condition, together with the fact that limited cooling cycles are expected during the operating life of the system, leads to the assumption that a progressive material hardening will occur in this area, thus locally raising the YS limit

Piattaforma 3DExperience: procedura operativa per la gestione del ciclo di vita di un prodotto e della documentazione di progetto

Il presente documento descrive la procedura operativa per la gestione del ciclo di vita di un prodotto e della documentazione di progetto, implementato dal “Reparto di Progettazione” del Servizio di Meccanica dei Laboratori Nazionali del Gran Sasso (LNGS) dell’INFN (Istituto Nazionale di Fisica Nucleare), attraverso la piattaforma di Project Life-Cycle Management della Dassault System “3DExperience”. Il documento descrive altresì l’integrazione della piattaforma con gli altri sistemi informativi messi a disposizione dall’INFN ai suoi dipendenti ed associati

Optical issues for the diagnostic stations for the ELI-NP compton gamma source

A high brightness electron Linac is being built in the Compton Gamma Source at the ELI Nuclear Physics facility in Romania. To achieve the design luminosity, a train of 32 bunches, 16 ns spaced, with a nominal charge of 250 pC will collide with the laser beam in the interaction point. Electron beam spot size is measured with optical transition radiation (OTR) profile monitors. In order to measure the beam properties, the optical radiation detecting system must have the necessary accuracy and resolution. This paper deals with the studies of different optic configurations to achieve the magnification, resolution and accuracy in order to measure very small beam (below 30 μm) or to study the angular distribution of the OTR and therefore the energy of the beam. Several configurations of the optical detection line will be studied both with simulation tools (e.g. Zemax) and experimentally. The paper will deal also with the sensibility of optic system (in terms of depth of field, magnification and resolution) to systematic error

The ASTAROTH project

The most discussed topic in direct search for dark matter is arguably the verification of the DAMA claim. In fact, the observed annual modulation of the signal rate in an array of NaI(Tl) detectors can be interpreted as the awaited signature of dark matter interaction. Several experimental groups are currently engaged in the attempt to verify such a game-changing claim with the same target material. However, all present-day designs are based on a light readout via Photomultiplier Tubes, whose high noise makes it challenging to achieve a low background in the 1-6 keV energy region of the signal. Even harder it would be to break below 1 keV energy threshold, where a large fraction of the signal potentially awaits to be uncovered. ASTAROTH is an R\&D project to overcome these limitations by using Silicon Photomultipliers (SiPM) matrices to collect scintillation light from NaI(Tl). The all-active design based on cubic crystals is operating in the 87-150 K temperature range where SiPM noise can be even a hundred times lower with respect to PMTs. The cryostat was developed following an innovative design and is based on a copper chamber immersed in a liquid argon bath that can be instrumented as a veto detector. We have characterized separately the crystal and the SiPM response at low temperature and we have proceeded to the first operation of a NaI(Tl) crystal read by SiPM in cryogeny.Comment: proceedings of the LRT 2022 conferenc

Valutazione della robustezza di un sistema di misura ferroviario mediante tecniche di “progettazione al calcolatore degli esperimenti" // Evaluation of the robustness of a railway measurement system by means of “design of computer experiments” techniques

In railway operations, data provided by wayside measuring systems could be useful for many reasons as ensuring safety and facilitating maintenance of the tracks. For example, measuring devices of wheel-rail contact forces allow the monitoring of any kind of rolling stock under specific operating conditions, like curves at low speed or twisted tracks, which are always present in stations, depots and marshalling yards. For that reason, in this paper we present the evaluation of the robustness of the SMCT wayside measurement system. The system is based on a particular strain gauges configuration on the rail foot, able to isolate the effects of the lateral force from those of the vertical one and record the lateral force using a proportional coefficient between that force and strains. The system has been validated with several field tests directly on a railway line in service: about 4000 transit and different types of trains, up to 110 km/h. The aim of the work is to build a fitting regression model able to predict the value of the ratio between the lateral force and strains in order to test the robustness of the measurement method and its operating range, modifying parameters that experimentally could not have been changed

Valutazione del rischio di collisione tra gru portuali nelle attività di carico e scarico delle merci alla rinfusa

La sempre più diffusa meccanizzazione delle operazioni di movimentazione dei carichi all’interno dei porti ha fatto sì che la progettazione di nuove soluzioni tec-niche e l’esecuzione di attività quali la manutenzione degli impianti esistenti, ab-biano assunto nel recente passato un ruolo sempre più importante ai fini della sicu-rezza sul lavoro. In tale contesto operativo, i veicoli e gli impianti di movimento, a causa delle loro intrinseca natura, rappresentano infatti una delle principali cause di infortunio grave o mortale. Risulta quindi imprescindibile applicare specifiche e dettagliate metodologie volte all’analisi ed alla valutazione completa dei rischi ad essi associati. In questo articolo saranno prese in considerazione le attività di carico e scarico delle merci da navi rinfusiere e verrà valutato il rischio di collisione tra le gru por-tuali attraverso l’applicazione di una metodologia di analisi semi-quantitativa e multicriterio. In un contesto produttivo di questo tipo non è possibile inoltre pre-scindere dall’analisi del fattore umano.The increasing mechanization of handling operations in the port activities pro-duced a new idea of design and maintenance of existing plants in order to guaran-tee the safety of workers. In this operating environment, handling systems repre-sent the main cause of injury or death because of their inherent nature. Therefore, it is essential to apply specific methodologies for the risk analysis. In this paper, we consider the operations of loading and unloading of goods from bulk carriers and we assess the risk of collision between port cranes using a semi-quantitative multi-criteria analysis. In the risk assessment, we also consider the analysis of human factor

Additive Manufacturing Design of an Argon Condenser Made with Pure Copper Powder for High-Purity Physics Applications. Technological Issues

Additive Manufacturing (AM) techniques give to designer great freedom as the possibility to rethink the classic geometrical shapes of common objects and it is well suitable for experimental physics research, where components production is based on unique prototype with high specialization and characteristics. In this paper, an AM design process of a heat exchanger for the condensation of argon using liquid nitrogen under cryogenics condition is proposed. The development of the condenser is part of the activities related to the “DarkSide” experiment. The work describes the AM approach considering the re-design of the condenser geometrical shape, the functional and performance constraints together with a focus on the technological issues of the processing of a pure copper powder with Selective Laser Melting (SLM) technology. Unfortunately, it was found that there are still technological issues related to the SLM process of pure copper due to its low-density and its high internal porosity