Hardening/softening behavior and reduced order modeling of nonlinear vibrations of rotating cantilever beams

This work addresses the large amplitude nonlinear vibratory behavior of a rotating cantilever beam, with applications to turbomachinery and turbopropeller blades. The aim of this work is twofold. Firstly, we investigate the effect of rotation speed on the beam nonlinear vibrations and especially on the hardening/softening behavior of its resonances and the appearance of jump phenomena at large amplitude. Secondly, we compare three models to simulate the vibrations. The first two are based on analytical models of the beam, one of them being original. Those two models are discretized on appropriate mode basis and solve by a numerical following path method. The last one is based on a finite-element discretization and integrated in time. The accuracy and the validity range of each model are exhibited and analyzed.Acknowledgments The French company Safran Snecma and the French Ministry of Research are thanked for the financial support of this study, through the PhD grant of the second author

Relation of mitral valve morphology and motion to mitral regurgitation severity in patients with mitral valve prolapse

<p>Abstract</p> <p>Background</p> <p>Mitral valve thickness is used as a criterion to distinguish the classical from the non-classical form of mitral valve prolapse (MVP). Classical form of MVP has been associated with higher risk of mitral regurgitation (MR) and concomitant complications. We sought to determine the relation of mitral valve morphology and motion to mitral regurgitation severity in patients with MVP.</p> <p>Methods</p> <p>We prospectively analyzed transthoracic echocardiograms of 38 consecutive patients with MVP and various degrees of MR. In the parasternal long-axis view, leaflets length, diastolic leaflet thickness, prolapsing depth, billowing area and non-coaptation distance between both leaflets were measured.</p> <p>Results</p> <p>Twenty patients (53%) and 18 patients (47%) were identified as having moderate to severe and mild MR respectively (ERO = 45 ± 27 mm²vs. 5 ± 7 mm², p < 0.001). Diastolic leaflet thickness was similar in both groups (5.5 ± 0.9 mm vs. 5.3 ± 1 mm, p = 0.57). On multivariate analysis, the non-coaptation distance (OR 7.9 per 1 mm increase; 95% CI 1.72-37.2) was associated with significant MR. Thick mitral valve leaflet as traditionally reported (≥ 5 mm) was not associated with significant MR (OR 0.9; 95% CI 0.2-3.4).</p> <p>Conclusions</p> <p>In patients with MVP, thick mitral leaflet is not associated with significant MR. Leaflet thickness is probably not as important in risk stratification as previously reported in patients with MVP. Other anatomical and geometrical features of the mitral valve apparatus area appear to be much more closely related to MR severity.</p

Potentially inappropriate medication use in older adults with mild-moderate Alzheimer's disease:Prevalence and associations with adverse events

Aim: Potentially inappropriate medication (PIM) use is prevalent in older adults and is associated with adverse events, hospitalisation and mortality. We assessed the patterns and associations of PIM use in older adults with mild-to-moderate Alzheimer's Disease (AD), who may represent a particularly vulnerable group. Design: Analysis of data from NILVad, an 18-month Randomised Control Trial of Nilvadapine in mild-to-moderate AD. The v2 STOPP criteria were applied in duplicate to identify PIM use. Associations between PIM use and adverse events/unscheduled healthcare visits in addition to the associations between PIM use and AD progression were evaluated. Setting and Participants: 448 older adults with mild-to-moderate AD from 23 centres in nine European countries. Results: Of 448 participants (mean age: 72.56 ± 8.19 years), over half (55.8%) were prescribed a PIM with 30.1% being prescribed 2+ PIMs. The most frequent PIMs were (i) long-term benzodiazepines (11.6% N = 52/448), (ii) selective serotonin reuptake inhibitors without appropriate indication (11.1% N = 50/448), and (iii) Proton-Pump Inhibitors (PPIs) without appropriate indication (10.7% N = 48/448). Increasing number of PIMs was associated with a greater risk of adverse events (IRR 1.17, 1.13-1.19, P &lt; 0.001), serious adverse events (IRR 1.27; 1.17-1.37, P &lt; 0.001), unscheduled hospitalisations (IRR 1.16, 1.03-1.30, P = 0.016) and GP visits (IRR 1.22, 1.15-1.28, P &lt; 0.001). PIM use was not associated with dementia progression. Conclusions and Implications: PIM use is highly prevalent in mild-to-moderate AD and is associated with adverse events and unscheduled healthcare utilisation. Further attention to de-prescribing in this vulnerable group is warranted

Conduite des systèmes de production durables

International audienceThe control of production systems is a management activity. Confronting a global pandemic, the scarcity of natural resources and climate change is a result to which it must contribute even if the control of production systems is relevant to the operational level of industrial engineering. In this context, control must therefore allow for environmental efficiency (of the production tool and of the technological solutions deployed in Industry 4.0), be based on the principle of solidarity-based opportunism, and jointly focus on the operation and maintenance of the production system. These principles are applied to a teaching platform on how to conduct the maintenance of a production system.La conduite des systèmes de production est une activité de pilotage. Faire face à une pandémie mondiale, à la raréfaction des ressources naturelles et au dérèglement climatique est un résultat auquel elle doit participer, même si elle relève du niveau opérationnel de la gestion industrielle. Dans ce contexte, la conduite doit donc permettre l’efficience environnementale (de l’outil de production, et des solutions technologiques déployées dans le cadre de l’industrie 4.0), être fondée sur le principe d’opportunisme solidaire, et porter conjointement sur l’exploitation et sur la maintenance du système de production. Ces principes sont appliqués à une plateforme d’enseignement sur la conduite de la maintenance d’un système de production

Concepts pour l'évaluation de la performance des systèmes de production

National audienceLa performance d'un système de production est plurielle et multidimensionnelle. Elle doit être évaluée globalement et sur l'ensemble du cycle vie du système et des produits réalisés. Elle intègre non seulement les notions de coût, délais, qualité, mais aussi de flexibilité, (capacité de changement rapide de la planification en cours et/ou modification de l'outil de production), de robustesse (comportement stable vis à vis de variations de la demande et d'occurrence d'aléas) et de valeur (liée à la satisfaction du client). Les facteurs humains et sociaux, longtemps sous-estimés, en sont des paramètres prépondérants. Il en résulte un besoin fort de méthodologies et d'outils pouvant aider les décideurs à mieux appréhender la notion de performance et à l'évaluer lors de la conception, l'exploitation et la reconfiguration d'un système de production. Cet ouvrage a pour objectif de décrire l'historique de l'évaluation de performance et de préciser le champ thématique qu'elle recouvre. Les auteurs y définissent le contexte dans lequel l'évaluation de performance doit se concevoir et se déployer, puis présentent, d'une part, un certain nombre d'expérimentations industrielles où les concepts et méthodes présentés dans les parties précédentes ont été mis en oeuvre et, d'autre part, plusieurs approches prospectives de l'évaluation de la performance

Evaluation de performance et proximité

National audienceLa performance d'un système de production est plurielle et multidimensionnelle. Elle doit être évaluée globalement et sur l'ensemble du cycle vie du système et des produits réalisés. Elle intègre non seulement les notions de coût, délais, qualité, mais aussi de flexibilité, (capacité de changement rapide de la planification en cours et/ou modification de l'outil de production), de robustesse (comportement stable vis à vis de variations de la demande et d'occurrence d'aléas) et de valeur (liée à la satisfaction du client). Les facteurs humains et sociaux, longtemps sous-estimés, en sont des paramètres prépondérants. Il en résulte un besoin fort de méthodologies et d'outils pouvant aider les décideurs à mieux appréhender la notion de performance et à l'évaluer lors de la conception, l'exploitation et la reconfiguration d'un système de production. Cet ouvrage a pour objectif de décrire l'historique de l'évaluation de performance et de préciser le champ thématique qu'elle recouvre. Les auteurs y définissent le contexte dans lequel l'évaluation de performance doit se concevoir et se déployer, puis présentent, d'une part, un certain nombre d'expérimentations industrielles où les concepts et méthodes présentés dans les parties précédentes ont été mis en oeuvre et, d'autre part, plusieurs approches prospectives de l'évaluation de la performance

Regeneration engineering for improving technical asset life cycle: an application to weapon systems availability assessment

International audienceToday, system availability is a determining factor in system deployment because it must be guaranteed in the operational phase while taking a large part of assets whole life cycle cost (WLCC). Thus, controlling system availability is now a critical issue in systems engineering. This is even more true for military systems that operate in a battle context. In fact, since they must act in a hostile environment, they can become unavailable due to system failures or damage. In both cases, it is necessary to regenerate the system in order to restore its availability in mission. In this paper, we propose a weapon system modelling method that supports regeneration engineering. This method relies on a unified failure/damage approach to extend accepted availability models. It integrates both failures and damage, as well as the possibility of regeneration, into the operational availability assessment. The proposed method is illustrated with an example of weapons system architecture

Optimization of shunted piezoelectric patches for vibration reduction of complex structures - Application to a turbojet fan blade

International audienc