On-board indirect measurements of the acoustic quality of railway track: state-of-the art and simulations

48th International Congress and Exposition on Noise Control Engineering (Inter-Noise 2019), MADRID, ESPAGNE, 16-/06/2019 - 19/06/2019Noise emission is a major concern for residents living along railway lines. For a large range of conventional speeds, railway noise is dominated by rolling noise. The contribution of the track to rolling noise is mainly driven by the level of rail roughness and the Track Decay Rate (TDR). The MEEQUAI project (on-board measurement of the acoustic quality of the infrastructure) aims to develop a system capable of measuring these characteristics using on-board instrumentation. A state-of-the-art on the subject shows that indirect measurement from vibro-acoustic sensors like axle-box accelerometers or microphones in the bogie area seems possible, but that a number of improvements could be made to the existing methods, especially in estimating the transfer functions between the e_ective roughness and the signals provided by the sensors. The idea is to combine modelling and measurements to optimize the estimation of the transfer functions and the location of sensors while taking into account the variability of circulated tracks. Numerical analyses of transfer functions based on axle/track vibro-acoustic models are performed. Based on the simulations results, several improvements are proposed, with a view to future tests in rolling conditions

Medium frequency phenomena on heavy vehicles: experimental analysis and numerical applications

Driveline vibrations of a truck are a cause of strong discomfort for drivers, and have to be investigated in pre-design phases. In order to develop numerical and analytical tools for the prediction of noise and vibration of such a complex structure, a deep knowledge of the physical phenomena involved is imperative. Few experimental studies have been performed on truck vibrations, and they mostly concerned single components of a vehicle. Therefore an Experimental Modal Analysis (EMA) of a complete truck has been performed in order to observe vibratory phenomena and determine influencing parameters involved in the vibration transmission. This study brings new insights into the field of truck vibrations. The results of the test campaign have been used for correlation with a numerical model and for the identification of dynamic behaviour and related frequency ranges. This work constitutes the preliminary part for an on-going project aiming at the development of reduced numerical models for the prediction of sound and vibration in truck cabins

Mesure embarquée de la qualité acoustique de l'infrastructure ferroviaire-Projet MEEQUAI

Journées Techniques Acoustique et Vibrations, STRASBOURG, FRANCE, 15-/05/2019 - 16/05/2019Pour les riverains des infrastructures ferroviaires, les émissions acoustiques constituent une préoccupation de premier plan. Parmi les sources incriminées, le bruit de roulement est prépondérant pour une large gamme de vitesses d'exploitation. Pour ce qui est de l'infrastructure, le niveau de bruit de roulement est principalement déterminé par deux paramètres : la rugosité des rails et le taux de décroissance des ondes vibratoires de la voie (TDR). Le projet MEEQUAI (MEsure Embarquée de la QUalité Acoustique de l'Infrastructure) vise à développer un système de mesure de la rugosité des rails et du taux de décroissance à l'aide de microphones et d'accéléromètres embarqués sur un train. Ce système a pour objectif principal d'améliorer la connaissance des données d'entrée pour la réalisation de cartographies acoustiques. Cependant, il ouvrira également de nouvelles opportunités pour le suivi dans le temps de la qualité acoustique des infrastructures ferroviaires ainsi que pour la maintenance des points singuliers tels que les joints de rail et les appareils de voie.Dans cette présentation, les mécanismes de génération du bruit de roulement sont présentés, notamment à travers le rôle de la rugosité et du taux de décroissance. Les principaux systèmes de mesure de ces paramètres sont passés en revue et les limites des méthodes indirectes examinées. Enfin, les résultats des premières études numériques et expérimentales réalisées dans le projet sont exposés. Ils valident les premières briques de l'approche retenue dans MEEQUAI

Serum Albumin Is Inversely Associated With Portal Vein Thrombosis in Cirrhosis

We analyzed whether serum albumin is independently associated with portal vein thrombosis (PVT) in liver cirrhosis (LC) and if a biologic plausibility exists. This study was divided into three parts. In part 1 (retrospective analysis), 753 consecutive patients with LC with ultrasound-detected PVT were retrospectively analyzed. In part 2, 112 patients with LC and 56 matched controls were entered in the cross-sectional study. In part 3, 5 patients with cirrhosis were entered in the in vivo study and 4 healthy subjects (HSs) were entered in the in vitro study to explore if albumin may affect platelet activation by modulating oxidative stress. In the 753 patients with LC, the prevalence of PVT was 16.7%; logistic analysis showed that only age (odds ratio [OR], 1.024; P = 0.012) and serum albumin (OR, -0.422; P = 0.0001) significantly predicted patients with PVT. Analyzing the 112 patients with LC and controls, soluble clusters of differentiation (CD)40-ligand (P = 0.0238), soluble Nox2-derived peptide (sNox2-dp; P < 0.0001), and urinary excretion of isoprostanes (P = 0.0078) were higher in patients with LC. In LC, albumin was correlated with sCD4OL (Spearman's rank correlation coefficient [r(s)], -0.33; P < 0.001), sNox2-dp (r(s), -0.57; P < 0.0001), and urinary excretion of isoprostanes (r(s), -0.48; P < 0.0001) levels. The in vivo study showed a progressive decrease in platelet aggregation, sNox2-dp, and urinary 8-iso prostaglandin F2 alpha-III formation 2 hours and 3 days after albumin infusion. Finally, platelet aggregation, sNox2-dp, and isoprostane formation significantly decreased in platelets from HSs incubated with scalar concentrations of albumin. Conclusion: Low serum albumin in LC is associated with PVT, suggesting that albumin could be a modulator of the hemostatic system through interference with mechanisms regulating platelet activation

Vibroacoustic coupling phenomena on heavy vehicles.Medium frequency experimental analysis and numerical applications for design specifications.

La prestation vibroacoustique est une question primordiale pour les constructeurs de véhicules, qui sont contraints par des lois ainsi que par des besoins commerciales: d'une part, un grand nombre de normes existe, visant à régler les niveaux vibratoires et acoustiques que les occupants d'un véhicule peuvent supporter, d'autre part le constructeur est intéressé à garantir un haut degré de confort pour que son produit soit compétitif. L'industrie du poids lourds comporte des spécificités par rapport à d'autres secteurs industriels, et surtout par rapport au marché des véhicules légers: non seulement l'architecture d'un véhicule industriel est unique, mais en plus ce qui caractérise les poids lourds par rapport à d'autres véhicules terrestres est la grande diversité des configurations disponibles. Une bonne connaissance des mécanismes de transmission des vibrations et du bruit, ainsi que du bilan de leurs sources, permette de fixer des règles de conception plus rigoureuses pour les composants. Par ailleurs, la connaissance des influences des paramètres architecturaux d'un camion sur les prestations vibroacoustiques donne une meilleure clé d'interprétation pour prédire les caractéristiques qu'un composant du véhicule doit avoir. Actuellement ces vérifications sont largement basées sur des essais, soit subjectifs (estimations par des techniciens experts) soit objectifs (acquisitions par microphones et accéléromètres). Cette pratique est très coûteuse car, pour prendre en compte la diversité des camions, il faut tester un grand nombre de véhicules. Pour franchir ces limitations, le prototypage virtuel - au lieu des essais physiques - doit être renforcé. Les méthodologies numériques sont déjà utilisées au sein du Groupe Volvo, mais les outils disponibles sont considérés en partie inappropriés pour les besoins de calcul des prestations NVH. Les activités de cette thèse ont été réalisées dans le cadre du service Noise and Driveline Vibration, qui est responsable de l'estimation du confort acoustique perçu par les occupants du camion, dans toutes ces conditions d'utilisation. Les travaux de thèse sont concentrés sur le comportement du châssis comme composant principale; le châssis est la principale voie de transfert des vibrations depuis le moteur vers la cabine. En outre, une attention particulière sera donnée à l'effet des accessoires sur le comportement dynamique du châssis, bien que peu d'intérêt sera porté sur la signature vibratoire des accessoires mêmes.The vibroacoustic performance is a matter of primary concern for modern vehicle manufacturers, that are constrained by health and safety legislation as well as by commercial needs: on the one hand, a number of norms exists regulating the level of vibration and noise that vehicle occupants can tolerate, but on the other hand a manufacturer is also interested in guaranteeing a high level of comfort in order to keep products competitive. The commercial vehicle industry presents some peculiarity with respect to other vehicle manufacturing businesses, and especially to the more known car industry: not only the architecture of a commercial vehicle is a class of its own, but what differentiates the most trucks from other ground vehicles are the configuration diversity and customization. A deep knowledge of the vibration and noise transmission mechanisms in trucks as well as source breakdown allows defining more rigorous and strict component specifications. Furthermore, the comprehension of the sensitivity of truck architecture parameters on vibroacoustic features provides even deeper means to assess the needed properties for a component to be installed on a vehicle. At present the verification is largely based on tests, both subjective (assessment by experimented test engineers) and objective (microphone and accelerometer acquisitions). This practice is extremely expensive, since, in order to take into account the large diversity of trucks, a large number of vehicles has to be tested. To overcome this limit, virtual testing - as opposed to physical testing - should be strengthened. Numerical methods are already largely used in the Volvo Group, but the available tools are considered partly unfit to the NVH demands and inappropriate with respect to their specific needs. The activities of the current thesis have been developed in the framework of the Interior Noise and Driveline Vibration group, which is responsible for the estimation of the acoustic comfort perceived by driver and passengers in all driving conditions and vehicle uses. This thesis will focus on the behaviour of the chassis as a primary component. The chassis is the main transfer path for engine-induced vibrations transmitted to the cabin. Besides, a peculiar attention will be given to the effect the chassis equipment components have on the chassis dynamics, even though limited interest will be put on the investigation of the dynamic signature of the equipment itself

Mesure embarquée de la qualité acoustique de l'infrastructure ferroviaire

Pour les riverains des infrastructures ferroviaires, les émissions acoustiques constituent une préoccupation de premier plan. Parmi les sources incriminées, le bruit de roulement est prépondérant pour une large gamme de vitesses d'exploitation. Pour ce qui est de l'infrastructure, le niveau de bruit de roulement est principalement déterminé par deux paramètres : la rugosité des rails et le taux de décroissance des ondes vibratoires de la voie (TDR). Le projet MEEQUAI (MEsure Embarquée de la QUalité Acoustique de l'Infrastructure) vise à développer un système de mesure de la rugosité des rails et du taux de décroissance à l'aide de microphones et d'accéléromètres embarqués sur un train. Ce système a pour objectif principal d'améliorer la connaissance des données d'entrée pour la réalisation de cartographies acoustiques. Cependant, il ouvrira également de nouvelles opportunités pour le suivi dans le temps de la qualité acoustique des infrastructures ferroviaires ainsi que pour la maintenance des points singuliers tels que les joints de rail et les appareils de voie.Dans cet article, les mécanismes de génération du bruit de roulement sont présentés, notamment à travers le rôle de la rugosité et du taux de décroissance. Les principaux systèmes de mesure de ces paramètres sont passés en revue et les limites des méthodes indirectes examinées. Enfin, les résultats des premières études numériques et expérimentales réalisées dans le projet sont exposés. Ils valident les premières briques de l'approche retenue dans MEEQUAI

Calibration of transfer functions on a standstill vehicle for on-board indirect measurements of rail acoustic roughness

Forum Acusticum, LYON, FRANCE, 07-/12/2020 - 11/12/2020On-board measurement of the acoustic performance of railway tracks is nowadays necessary to qualify networks on a large scale. The issue concerns not only the supply of prediction models for strategic noise mapping, but also the optimization of track maintenance. One of the key parameters to be measured is the rail acoustic roughness. Unlike direct measurements where sensors are directly applied to the rail surface, indirect measurements of rail roughness focus on quantities that result from wheel/rail interaction, such as noise or vibrations of axle-boxes or rail, and from which the effective wheel/rail combined roughness are estimated. In particular, on-board measurements make the qualification of long track lengths possible without major constraints on traffic. A number of improvements can be made to the existing methods, especially in estimating the transfer functions between the effective roughness and the signals provided by the sensors. This study is part of the MEEQUAI French project aiming to combine modelling and measurements to optimize the estimation of the transfer functions and the location of sensors while taking into account the variability of tracks. This paper concerns the measurement performed on a static vehicle/track configuration in order to validate and calibrate the numerical simulations

The use of nonselective beta blockers is a risk factor for portal vein thrombosis in cirrhotic patients

Background/Aim: A reduction in portal vein inflow velocity seems to predispose to the emergence of portal vein thrombosis (PVT). Nonselective β-blockers (NSBBs), used to prevent variceal bleeding, may increase the development of PVT by reducing portal vein inflow velocity. In this retrospective case-control study, we evaluated the risk factors and clinical features of a first event of PVT in 130 cirrhotics, 19 (15%) with (PVT group) and 111 (85%) without PVT (non-PVT group). Patients and Methods: Patient evaluation and NNBB treatment were carried out according to the AASLD guidelines. Results: PVT was prevalently partial (84%) and asymptomatic (84%). Patients with PVT were treated with different regimens, and resolution of thrombosis was observed in about 50% of the cases. In both groups, HCV was the most frequent cause of cirrhosis and Child-Pugh score A was prevalent. Ascites and esophageal varices were more frequent in the PVT group (P = 0.05 and <0.000, respectively). Treatment with NSBBs was significantly more frequent in the PVT group than in the non-PVT group (P < 0.000). PVT was associated with higher prevalence of chronic renal disease (P = 0.002), higher PT impairment (P = 0.003) and lower AST and ALT (P = 0.000). At multivariate logistic regression analysis, history of esophageal varices (P = 0.007) and NSBB treatment (P = 0.0003) were independent risk factors significantly associated with PVT. Conclusions: Esophageal varices and NSBB treatment were independent risk factors of PVT. Larger studies should evaluate the risk between variceal bleeding and portal vein thrombosis of using NSBBs, particularly in the prevention of first bleeding in nonadvanced liver cirrhosis

Paediatric arterial ischaemic stroke and cerebral sinovenous thrombosis: First report from the Italian registry of pediatric thrombosis (R. I. T. I., Registro Italiano Trombosi Infantili)

reserved55noData from large case series of children with cerebral thrombotic events are pivotal to improve prevention, early recognition and treatment of these conditions. The Italian Registry of Pediatric Thrombosis (R. I. T. I.) was established in 2007 by a multidisciplinary team, aiming for a better understanding of neonatal and paediatric thrombotic events in Italy and providing a preliminary source of data for the future development of specific clinical trials and diagnostic-therapeutic protocols. We analysed data relative to the paediatric cerebral thrombotic events of the R. I. T. I. which occurred between January 2007 and June 2012. In the study period, 79 arterial ischaemic stroke (AIS) events (49 in males) and 91 cerebral sinovenous thrombosis (CSVT) events (65 in males) were enrolled in the R. I. T. I. Mean age at onset was 4.5 years in AIS, and 7.1 years in CSVT. Most common modes of presentation were hemiparesis, seizures and speech disturbances in AIS, and headache, seizures and lethargy in CSVT. Most common etiologies were underlying chronic diseases, vasculopathy and cardiopathy in AIS, and underlying chronic diseases and infection in CSVT. Time to diagnosis exceeded 24 hours in 46% AIS and 59% CSVT. Overall data from the Italian Registry are in substantial agreement with those from the literature, despite small differences. Among these, a longer time to diagnosis compared to other registries and case series poses the accent to the need of an earlier recognition of paediatric cerebrovascular events in Italy, in order to enable prompt and effective treatment strategies.mixedSuppiej A.; Gentilomo C.; Saracco P.; Sartori S.; Agostini M.; Bagna R.; Bassi B.; Giordano P.; Grassi M.; Guzzetta A.; Lasagni D.; Luciani M.; Molinari A.C.; Palmieri A.; Putti M.C.; Ramenghi L.A.; Rota L.L.; Sperli D.; Laverda A.M.; Simioni P.; Angriman M.; Aru A.B.; Barisone E.; Bartalena L.; Berta M.; Bertoni E.; Cancarini P.; Cavaliere E.; Celle M.E.; Cerbone A.M.; Cesaroni E.; Via L.D.; Dell'Oro M.G.; Di Rosa G.; Ferrari G.M.; Fiori S.; Gaffuri M.; Gallina M.R.; Gimmillaro A.; Grandone E.; Ladogana S.; Laforgia N.; La Piana R.; Maschio F.; Miniero R.; Nosadini M.; Panzeri D.; Petrucci A.; Piersigilli F.; Sala D.; Sangermani R.; Santoro N.; Tufano A.; Ventura G.; Vittorini R.Suppiej, A.; Gentilomo, C.; Saracco, P.; Sartori, S.; Agostini, M.; Bagna, R.; Bassi, B.; Giordano, P.; Grassi, M.; Guzzetta, A.; Lasagni, D.; Luciani, M.; Molinari, A. C.; Palmieri, A.; Putti, M. C.; Ramenghi, L. A.; Rota, L. L.; Sperli, D.; Laverda, A. M.; Simioni, P.; Angriman, M.; Aru, A. B.; Barisone, E.; Bartalena, L.; Berta, M.; Bertoni, E.; Cancarini, P.; Cavaliere, E.; Celle, M. E.; Cerbone, A. M.; Cesaroni, E.; Via, L. D.; Dell'Oro, M. G.; Di Rosa, G.; Ferrari, G. M.; Fiori, S.; Gaffuri, M.; Gallina, M. R.; Gimmillaro, A.; Grandone, E.; Ladogana, S.; Laforgia, N.; La Piana, R.; Maschio, F.; Miniero, R.; Nosadini, M.; Panzeri, D.; Petrucci, A.; Piersigilli, F.; Sala, D.; Sangermani, R.; Santoro, N.; Tufano, A.; Ventura, G.; Vittorini, R