Stochastic analysis of a radial-inflow turbine in the presence of parametric uncertainties

This paper presents an uncertainty quantification study of the performance analysis of the high pressure ratio single stage radial-inflow turbine used in the Sundstrand Power Systems T-100 Multi-purpose Small Power Unit. A deterministic 3D volume-averaged Computational Fluid Dynamics (CFD) solver is coupled with a non-statistical generalized Polynomial Chaos (gPC) representation based on a pseudo-spectral projection method. One of the advantages of this approach is that it does not require any modification of the CFD code for the propagation of random disturbances in the aerodynamic and geometric fields. The stochastic results highlight the importance of the blade thickness and trailing edge tip radius on the total-to-static efficiency of the turbine compared to the angular velocity and trailing edge tip length. From a theoretical point of view, the use of the gPC representation on an arbitrary grid also allows the investigation of the sensitivity of the blade thickness profiles on the turbine efficiency. The gPC approach is also applied to coupled random parameters. The results show that the most influential coupled random variables are trailing edge tip radius coupled with the angular velocity

Coping with citizen demands: a field study of suckling processes in dairy herds

In dairy farms calves and cows are usually separated shortly after birth but this practice raises the question of animal welfare. This social concern may lead to bring back dairy calves to their mother. Even though suckling is quite seldom in dairy production, some farmers are using such a practice for many years. The present study aims to better know farmer’s motivations, practical implementation and farmer’s perception of the impact of suckling on performance and animal behaviour. In January 2018 a semi-quantitative survey was performed on 44 farms where calves suckle at least 24 hours their mother or a nurse cow. The farming systems differed on the size (20 to 140 cows), the type (19 conventional, 25 organic farms), the suckling (28 by the mothers, 16 by nurses), and the breed. Results indicate that main farmers’ motivations are calves’ health (52%), better working conditions (41%) and saving time (34%), with little consideration on animal welfare (7%). Numerous practices were found in terms of allowance of daily cow-calf contact and suckling duration with a difference between male and female calves. According to farmers, these practices were efficient to improved calves’ health (70%), save time (75%) and improved working conditions (52%). Weaning was considered as a stressful situation, especially after long suckling periods. Cow mooing usually stopped 2.5 d after weaning. At least 34 farmers are fully satisfied with this practice. The main challenge appears to be the management of the wildness of future heifers, by investing time to manipulate calves before weaning. The results of this survey could help to propose solutions to farmers who want to cope with the societal demand of keeping calves with dams in dairy herds

Déléguer l'allaitement des veaux laitiers aux vaches ? Résultats d'enquêtes auprès des éleveurs

La séparation précoce mère-veau est une pratique courante dans la plupart des élevages laitiers, mais est sujette à de nombreuses interrogations tant chez les éleveurs (coûts engendrés, travail) que dans la société (bien-être animal). Des pratiques alternatives mises en place par certains éleveurs permettent aux veaux d'être allaités par leur mère ou une autre vache, appelée « nourrice ». Quoiqu’anciennes, ces pratiques demeurent peu connues et leur intégration aux conditions d’élevages modernes questionne. Des enquêtes ont ainsi été réalisées en 2018 pour connaître la motivation des éleveurs, la diversité et les conséquences de ces pratiques sur les résultats techniques. Cent deux élevages, identifiés par des réseaux divers (conseil en élevage, chambres d’agriculture, coopératives…), ont été enquêtés dans le Grand Ouest (n = 50), le Grand Est (n = 41) et le Massif central (n = 11), par téléphone (n = 56) ou sur place (n = 46). La taille médiane des troupeaux est de 60 vaches laitières (8 à 210), principalement constitués de vaches de race Montbéliarde et Holstein. Les élevages sont pour moitié en agriculture biologique (56%), avec une grande diversité de systèmes de traite et de logement (salle de traite en épi, robot, stabulation entravée, libre à logettes…). Trois grandes conduites d'allaitement des veaux, de la naissance à la vente ou au sevrage, ont été identifiées : 1/ les veaux sont allaités exclusivement par leur mère ; 2/ les veaux sont élevés par leur mère puis reçoivent une alimentation lactée artificielle (poudre ou lait entier) ; 3/ les veaux sont élevés par leur mère puis sous une vache nourrice. Elles diffèrent souvent au sein d’un même élevage (n = 62) entre les veaux destinés à la vente (mâles ou femelles) et les velles de renouvellement. La diversité des systèmes d'allaitement se retrouve dans tous les types d'élevages, quelle que soit leur taille ou leur localisation géographique. L'amélioration de la santé des animaux (n = 52), la diminution du temps de travail (n = 47) et des coûts d’élevage (n = 32) sont les principales motivations des éleveurs à mettre en place ces pratiques. Pour 80% d’entre eux, ces pratiques alternatives ont entrainé une diminution de la fréquence des diarrhées des veaux et une amélioration de leur croissance. La séparation tardive vache-veau demeure le point négatif de ces pratiques, avec des périodes de meuglements de 2,4 jours en moyenne. Certains éleveurs, ayant utilisé puis abandonné ces pratiques, pointent aussi d’autres limites (problèmes sanitaires, bâtiments inadaptés). Cette enquête, qui a permis de mieux connaître les pratiques d'allaitement des veaux laitiers par leur mère et sous nourrice, va être complétée par des enquêtes similaires et des expérimentations en fermes, au niveau européen, afin d’avoir une vision plus large de ces pratiques et de leurs impacts

Authentication of cow feeding and geographic origin on milk using visible and near-infrared spectroscopy.

International audience; The ability of near-infrared spectroscopy to trace cow feeding systems and farming altitude was tested on 486 bulk milk samples from France and northwestern Italy. Milks were grouped into feeding systems according to the main forage in the diet. Partial least square discriminant analysis correctly classified 95.5, 91.5, and 93.3% of pasture versus maize silage, hay, and fermented herbage feeding systems, respectively. Discrimination was slightly less successful when diets with large proportions of the nondominant forage were included in each group. Near-infrared spectroscopy correctly discriminated no-pasture from pasture milk, even with only 30% of pasture in the diet (5.4% cross-validation error), and the error stabilized when pasture exceeded 70% (2.5% error). Near-infrared spectroscopy did not reliably trace milk geographic origin when the feeding system effect was isolated from the altitude effect. These findings may be usefully exploited for the authentication of dairy products

Genetics of anophthalmia and microphthalmia. Part 1, Non-syndromic anophthalmia/microphthalmia

Eye formation is the result of coordinated induction and differentiation processes during embryogenesis. Disruption of any one of these events has the potential to cause ocular growth and structural defects, such as anophthalmia and microphthalmia (A/M). A/M can be isolated or occur with systemic anomalies, when they may form part of a recognizable syndrome. Their etiology includes genetic and environmental factors; several hundred genes involved in ocular development have been identified in humans or animal models. In humans, around 30 genes have been repeatedly implicated in A/M families, although many other genes have been described in single cases or families, and some genetic syndromes include eye anomalies occasionally as part of a wider phenotype. As a result of this broad genetic heterogeneity, with one or two notable exceptions, each gene explains only a small percentage of cases. Given the overlapping phenotypes, these genes can be most efficiently tested on panels or by whole exome/genome sequencing for the purposes of molecular diagnosis. However, despite whole exome/genome testing more than half of patients currently remain without a molecular diagnosis. The proportion of undiagnosed cases is even higher in those individuals with unilateral or milder phenotypes. Furthermore, even when a strong gene candidate is available for a patient, issues of incomplete penetrance and germinal mosaicism make diagnosis and genetic counselling challenging. In this review, we present the main genes implicated in nonsyndromic human A/M phenotypes and, for practical purposes, classify them according to the most frequent or predominant phenotype each is associated with. Our intention is that this will allow clinicians to rank and prioritize their molecular analyses and interpretations according to the phenotypes of their patients

Tangling clustering of inertial particles in stably stratified turbulence

We have predicted theoretically and detected in laboratory experiments a new type of particle clustering (tangling clustering of inertial particles) in a stably stratified turbulence with imposed mean vertical temperature gradient. In this stratified turbulence a spatial distribution of the mean particle number density is nonuniform due to the phenomenon of turbulent thermal diffusion, that results in formation of a gradient of the mean particle number density, \nabla N, and generation of fluctuations of the particle number density by tangling of the gradient, \nabla N, by velocity fluctuations. The mean temperature gradient, \nabla T, produces the temperature fluctuations by tangling of the gradient, \nabla T, by velocity fluctuations. These fluctuations increase the rate of formation of the particle clusters in small scales. In the laboratory stratified turbulence this tangling clustering is much more effective than a pure inertial clustering that has been observed in isothermal turbulence. In particular, in our experiments in oscillating grid isothermal turbulence in air without imposed mean temperature gradient, the inertial clustering is very weak for solid particles with the diameter 10 microns and Reynolds numbers Re =250. Our theoretical predictions are in a good agreement with the obtained experimental results.Comment: 16 pages, 4 figures, REVTEX4, revised versio

Reducing Uncertainties in a Wind-Tunnel Experiment using Bayesian Updating

We perform a fully stochastic analysis of an experiment in aerodynamics. Given estimated uncertainties on the principle input parameters of the experiment, including uncertainties on the shape of the model, we apply uncertainty propagation methods to a suitable CFD model of the experimental setup. Thereby we predict the stochastic response of the measurements due to the experimental uncertainties. To reduce the variance of these uncertainties a Bayesian updating technique is employed in which the uncertain parameters are treated as calibration parameters, with priors taken as the original uncertainty estimates. Imprecise measurements of aerodynamic forces are used as observational data. Motivation and a concrete application come from a wind-tunnel experiment whose parameters and model geometry have substantial uncertainty. In this case the uncertainty was a consequence of a poorly constructed model in the pre-measurement phase. These methodological uncertainties lead to substantial uncertainties in the measurement of forces. Imprecise geometry measurements from multiple sources are used to create an improved stochastic model of the geometry. Calibration against lift and moment data then gives us estimates of the remaining parameters. The effectiveness of the procedure is demonstrated by prediction of drag with uncertainty

Universality classes in Burgers turbulence

We establish necessary and sufficient conditions for the shock statistics to approach self-similar form in Burgers turbulence with L\'{e}vy process initial data. The proof relies upon an elegant closure theorem of Bertoin and Carraro and Duchon that reduces the study of shock statistics to Smoluchowski's coagulation equation with additive kernel, and upon our previous characterization of the domains of attraction of self-similar solutions for this equation

USING VIRTUAL OR AUGMENTED REALITY for the TIME-BASED STUDY of COMPLEX UNDERWATER ARCHAEOLOGICAL EXCAVATIONS

International audienceCultural Heritage (CH) resources are partial, heterogeneous, discontinuous, and subject to ongoing updates and revisions. The use of semantic web technologies associated with 3D graphical tools is proposed to improve access, exploration, exploitation and enrichment of these CH data in a standardized and more structured form. This article presents the monitoring work developed for more than ten years on the excavation of the Xlendi site. Around an exceptional shipwreck, the oldest from the Archaic period in the Western Mediterranean, we have set up a unique excavation at a depth of 110m assisted by a rigorous and continuous photogrammetry campaign. All the collected results are modelled by an ontology and visualized with virtual and augmented reality tools that allow a bidirectional link between the proposed graphical representations and the non-graphical archaeological data. It is also important to highlight the development of an innovative 3D mobile app that lets users study and understand the site as well as experience sensations close to those of a diver visiting the site