Comportamento sperimentale di cuscinetti portanti lubrificati operanti a bassi numeri di Sommerfeld

In questa memoria viene descritto il comportamento sperimentale di un cuscinetto cilindrico portante lubrificato in condizioni di funzionamento critiche, ovvero a velocità di rotazione molto basse ed in presenza di elevata pressione specifica. Il cuscinetto utilizzato ha diametro nominale di 160 mm e lunghezza pari a 145 mm. La velocità di rotazione considerata è pari a 60 rpm (1 Hz), mentre i carichi applicati in direzione verticale variano da 20 kN a 350 kN, il che corrisponde a numeri di Sommerfeld variabili tra 0,1314 e 0,0086. Verranno presentati e discussi i dati ottenuti per la posizione di equilibrio statico, per la pressione idrodinamica, per la distribuzione di temperatura e per i coefficienti di rigidezza e smorzamento dinamici

Numerical Evaluation of Alford Forces Acting on an Axial Expander for Supercritical CO2 Application

Nowadays, supercritical carbon dioxide (S-CO2) cycles are of great interest in the scientific research especially considering the energy transition that is occurring. The S-CO2 high density and relatively low viscosity make it an interesting fluid for power generation. For large heat sources, large flowrates of fluid can be obtained. Therefore, the development of axial flow expanders can allow large power generations. In the presence of rotor eccentricities, the aerodynamic loading of free-standing blades is not constant tangentially and will promote the lateral vibration of the rotor. The dynamic phenomenon that arises is known as Thomas-Alford force. The Thomas-Alford force determines an increase of the vibration level of the machine and a higher risk of instabilities. In this paper, a preliminary investigation of a S-CO2 axial expander stage is performed. Different correlations proposed in the literature are adopted to estimate the magnitude of the Thomas-Alford force. A mono-dimensional code and a simplified computational fluid dynamics (CFD) model are adopted to obtain the parameters of the stage considered. In this preliminary investigation, only free-standing blades are considered. The results obtained show a good agreement between 1D and CFD inputs required by the different correlation used. Despite this, the cross coupled stiffness calculated are widely dependent on the correlation used; then, this study can be considered as the starting point for more detailed investigations validating the correlations behavior in this environment through an unsteady CFD and/or a proper test campaign

Liver resection of hepatocellular carcinoma in HIV-HCV co-infected patients: a retrospective case series

Abstract Introduction Despite the effectiveness of new therapies and awareness campaigns, the number of seropositive patients is increasing every year. Recently, other causes of death, not directly related to HIV, have emerged, such as chronic liver disease. The risk of hepatocellular carcinoma (HCC) is seven times greater in HIV patients than in noninfected patients, and it is especially attributable to HCV infection. The aim of our study was to evaluate clinical outcomes of HCC in HIV-HCV co-infected patients after liver resection (LR). Materials and methods The current study was conducted on a prospective database and reviewed retrospectively. All consecutive patients with HCC treated by LR from January 2013 to March 2019 at the Luigi Sacco University Hospital in Milan were enrolled. We included patients older than 18 years of age with HCV-related HCC, and in this set of patients, we identified two groups based on the presence of HIV infection. Results We identified 16 patients with HCV infection and precisely five with HIV-HCV co-infection and eleven with HCV infection alone. All HIV patients were male against 72.7% in the non-HIV group (p = 0.509). All patients had optimal HIV virologic control and a normal CD4 T-cell count. The mean diagnosis-to-treatment interval was statistically different between the two groups (HIV versus non-HIV: 1.2 ± 0.55 months versus 2.39 ± 1.09 months, p = 0.039). No other significant differences were found between HIV-HCV co-infected patients and HCV-infected patients. Long-term outcomes in terms of OS and RFS were similar between the two groups. Conclusions With a multidisciplinary approach and intensive support, LR can be a safe and efficacious procedure in HIV-HCV patients. For these reasons, we should not exclude potential patients merely on the basis of their HIV seropositivity

Analisi teorica e sperimentale dell’effetto della direzione del carico in cuscinetti a pattini oscillanti reali

I cuscinetti portanti a pattini oscillanti sono ampiamente utilizzati nelle macchine rotanti per velocità elevate e carichi sia bassi sia elevati. Data l’importanza di questo componente delle macchine rotanti, molti autori hanno pubblicato diversi studi, teorici e sperimentali, per valutare l’effetto dei giochi, della temperatura del lubrificante, della portata dell’olio e di diversi effetti termici sul comportamento di questo tipo di cuscinetto. Tuttavia, le indagini sull’influenza della direzione di carico sulle proprietà dei cuscinetti a pattini oscillanti sono spesso molto limitate e non considerano le geometria reale del cuscinetto. In questo articolo verrà presentata un’analisi teorica e sperimentale degli effetti delle direzione del carico nei cuscinetti reali a pattini oscillanti

Scrivere la LIS con il Sign Writing. Manuale introduttivo

Abstract not availableQuesto manuale nasce da un\u27intuizione, quella di poter utilizzare un sistema per trascrivere la Lingua dei Segni Italiana (LIS), adattando ai segni italiani il Sign Writing, ideato nel 1995 da Valerie Sutton (1995) e proposto come "un alfabeto per scrivere le lingue dei segni". La LIS infatti, come le altre lingue dei segni, non ha una corrispettiva forma scritta ed è stata tramandata di generazione in generazione dalla comunità sorda. La mancanza di una forma scritta, del resto comune a molte altre lingue, ha avuto tutta una serie di implicazioni nella storia della comunità sorda e la possibilità di utilizzare un sistema di trascrizione - come ha detto Valerie Sutton - può aprire nuove frontiere della comunicazione per i segnanti. L\u27attuale generazione di persone sorde adulte, che sta imparando a leggere e a scrivere le lingue segnate per la prima volta, sta creando la base per il lavoro delle generazioni future

Condition monitoring of the rolling stock and infrastructure: results of a pilot project

The application of Prognostics and Health Monitoring (PHM) concepts in rail vehicles and railway infrastructure is a rapidly growing field of research, and extensive efforts are being spent with the aim of improving the reliability and availability of railway systems and of substantially reducing maintenance costs by switching from time-based to event-driven maintenance policies. This paper presents the results of a research project in which concepts were developed and demonstrated for the health monitoring of the rolling stock (traction equipment) and of the railway infrastructure (track and overhead equipment). A prototype monitoring system was installed on a E464 locomotive and results were gathered across a time span of 14 months from December 2014 to January 2016

Rehabilitation of Difficult-to-Wean, Tracheostomized Patients Admitted to specialized unit: Retrospective Analyses Over 10-years.

Introduction: Rehabilitation outcomes of difficult-to-wean tracheostomized patients have been reported in relatively small case studies and described for a limited time span. This study de-scribes the characteristics and clinical outcomes of a large cohort of tracheostomized patients admitted to a specialized weaning unit over 10 years. Methods: We retrospectively analyzed da-ta collected from January 2010 to December 2019 on difficult-to-wean tracheostomized patients who underwent comprehensive rehabilitation. Clinical characteristics collected at admission were the level of comorbidity (by the Cumulative Illness Rating Scale \u2013 CIRS) and the clinical se-verity (by the Simplified Acute Physiology Score \u2013 SAPS II). The proportions of patients weaned, decannulated, and able to walk, the change in autonomy level according to the Bristol Activities of Daily Living (BADL) Scale, and the setting of hospital discharge was assessed and compared in a consecutive 5-year time periods (2010-2014 and 2015-2019) subgroup analysis. Results: A to-tal of 180 patients were included in the analysis. Patients\u2019 anthropometry and preadmission clin-ical management in acute care hospital were similar across years, but the categories of underlying diagnosis changed (p<0.001) (e.g. chronic obstructive pulmonary disease \u2013 COPD \u2013 decreased), while the level of comorbidities increased (p=0.003). Decannulation rate was 45.6%. CIRS and SAPS II at admission were both significant predictors of clinical outcomes. The proportion of pa-tients whose gain in BADL score increased 652 points decreased over time. Conclusions: This study confirms the importance of rehabilitation in the weaning units for the severely disabled subset of tracheostomized patients. Comorbidities and severity at admission are significantly as-sociated with rehabilitation outcomes at discharge

Dalla modalità faccia-a-faccia ad una lingua scritta emergente: nuove prospettive su trascrizione e scrittura della Lingua dei Segni italiana (LIS).

International audienceThis paper presents preliminary findings from research using SignWriting (SW) for representing Italian Sign Language (LIS) in written form. Our analyses are based on three LIS narrative texts elicited from three signers via the presentation of Chafe’s (1980) “Pear Story” film including: - a transcription from a video-recorded, face-to-face signed production; - two texts conceived and expressed directly in written LIS. We describe and discuss similarities and differences in the symbolization processes linked to the communication modalities. We show how SW-encoded representations highlight the differences existing between face-to-face interaction and written expression, as well as between “transcription” and “original” writings. These written representations also provide a powerful methodological tool for improving the analysis of LIS and enhancing metalinguistic reflections on LIS texts in ways until now impossible with other notation systems.Cet article présente les résultats préliminaires d'une recherche qui utilise SignWriting (SW) pour la représentation écrite de la Langue des Signes italienne (LIS). Les analyses sont fondées sur trois textes narratifs en LIS inspirés chez trois signeurs après avoir assisté à la vision du film "Pear Story" (Chafe, 1980), avec: la transcription d'une production singée en face-à-face et vidéo-enregistrée, deux textes directement conçus et exprimés en LIS écrite. Les auteurs décrivent et analysent les similitudes et les différences dans les processus de symbolisation liés à la modalité de communication. Il est ensuite montré que les représentations codifiées par SW mettent en évidence les différences qui existent entre l’interaction face-à-face et l’expression écrite, ainsi qu'entre "transcriptions" et écrits "originaux". Ces représentations écrites constituent un outil méthodologique puissant pour améliorer l'analyse de la LIS et valoriser les réflexions métalinguistiques sur des textes de LIS, selon des modalités jusqu’à présent impossibles avec d’'autres systèmes de notation.Questo documento presenta i risultati preliminari di una ricerca che usa SignWriting (SW) per la rappresentazione in forma scritta della Lingua dei Segni Italiana (LIS). Le analisi si basano su tre testi narrativi in LIS ispirati in tre segnanti via la visione del film "Pear Story" (Chafe, 1980), tra cui: una trascrizione di una produzione segnata faccia-a-faccia e videoregistrata; due testi direttamente concepiti ed espressi in LIS-scritta. Gli Autori descrivono e discutono le somiglianze e le differenze nei processi di simbolizzazione legati alla modalità di comunicazione. Viene poi mostrato come le rappresentazioni codificate tramite SW evidenzino le differenze esistenti tra interazione faccia-a-faccia e l'espressione scritta, nonché tra "trascrizione" e scritti "originali". Queste rappresentazioni scritte forniscono anche un potente strumento metodologico per migliorare l'analisi della LIS e per valorizzare le riflessioni metalinguistiche su testi LIS, in modi finora impossibili con altri sistemi di annotazione

How do cardiologists select patients for dual antiplatelet therapy continuation beyond 1 year after a myocardial infarction? Insights from the EYESHOT Post-MI Study

Background: Current guidelines suggest to consider dual antiplatelet therapy (DAPT) continuation for longer than 12 months in selected patients with myocardial infarction (MI). Hypothesis: We sought to assess the criteria used by cardiologists in daily practice to select patients with a history of MI eligible for DAPT continuation beyond 1 year. Methods: We analyzed data from the EYESHOT Post-MI, a prospective, observational, nationwide study aimed to evaluate the management of patients presenting to cardiologists 1 to 3 years from the last MI event. Results: Out of the 1633 post-MI patients enrolled in the study between March and December 2017, 557 (34.1%) were on DAPT at the time of enrolment, and 450 (27.6%) were prescribed DAPT after cardiologist assessment. At multivariate analyses, a percutaneous coronary intervention (PCI) with multiple stents and the presence of peripheral artery disease (PAD) resulted as independent predictors of DAPT continuation, while atrial fibrillation was the only independent predictor of DAPT interruption for patients both at the second and the third year from MI at enrolment and the time of discharge/end of the visit. Conclusions: Risk scores recommended by current guidelines for guiding decisions on DAPT duration are underused and misused in clinical practice. A PCI with multiple stents and a history of PAD resulted as the clinical variables more frequently associated with DAPT continuation beyond 1 year from the index MI

Experimental evidences of a cylindrical journal bearing operating at very low Sommerfeld numbers

In this paper the experimental behavior of a cylindrical journal bearing working in critical conditions, namely at very low speed and high specific pressure, is described. A bearing with the nominal diameter of 160mm and the length of 145mm was used. The rotational speed was fixed at 60rpm (1Hz), while the applied load varied from 20kN to 350kN in the vertical direction, corresponding to the Sommerfeld number ranges from 0.1314 to 0.0086. Measurements of static position, hydrodynamic pressure, temperature profiles, and dynamic coefficients have been presented and discussed