Experimental analysis of the pressure–velocity correlations of external unsteady flow over rocket launchers

Based on simultaneous wall pressure and velocity measurements, the aerodynamic load of a launcher body model is investigated. Two different configurations are considered in order to study the influence of geometrical artifacts on the after body flow and consequently on the aerodynamic load. After a brief presentation of the experimental setup used to get the unsteady wall pressure and external velocity field, a global analysis of the integrated pressure along the nozzle is presented for both configurations. It is shown that the unsteady load induced on a configuration with attachment device involves characteristic frequencies which fits the mechanical response of the structure whereas no particular behavior is observed on the configuration without attachment device. Then, a Proper Orthogonal Decomposition is successively performed from the wall pressure field and from the external velocity field highlighting the relationship between the most energetic structures of the flow and the involved phenomenon. Finally, a pressure/velocity correlation of the POD modes is presented and the most energetic structures of the velocity field are linked to the unsteady load observed on the nozzle. It is then confirmed the structural influence of the attachment device and its contribution to the unsteady loads acting on the nozzle.ESA TRP: "Unsteady Subscale Force Measurements within a Launch Vehicle Base Buffeting Environment"

From Sensors to Visualization Dashboards: Need for Language Composition

International audienceIn the context of the Internet of Things, the SensApp platform is designed to collect data from sensors and support the building of associated monitoring dashboards. Bridging the gap between sensors and visualization involves up to eleven kind of models, from state machine modeling the behavior of a sensor to task diagrams modeling the actions of the end-user. This paper describes this case study, emphasizing the need for domain specific modeling language composition mechanisms to support the activity of modeling modern software-intensive systems

Coming of age: report on the euro area

This report surveys the economic performance of the euro area and gives recommendations about six policy challenges of major importance for the future of EMU.

Aircraft and MiniCAST soot at the nanoscale

International audienc

Inhibition of markers of bone resorption by consumption of vitamin D and calcium-fortified soft plain cheese by institutionalised elderly women

Acceleration of bone remodelling increases the risk of fragility fractures. The objective of the present study was to explore in elderly women whether a vitamin D and Ca-fortified dairy product providing about 17-25% of the recommended intakes in vitamin D, Ca and proteins would reduce secondary hyperparathyroidism and bone remodelling in a way that may attenuate age-related bone loss in the long term. Thirty-seven institutionalised women, aged 84·8 (sd 8·1) years, with low serum 25-hydroxyvitamin D (5·5 (sd 1·7) ng/ml) were enrolled into a multicentre open trial to consume during 1 month two servings of soft plain cheese made of semi-skimmed milk providing daily 686kJ (164kcal), 2·5μg vitamin D, 302mg Ca and 14·2g proteins. The primary endpoint was the change in serum carboxy terminal cross-linked telopeptide of type I collagen (CTX), selected as a marker of bone resorption. Thirty-five subjects remained compliant. Mean serum changes were: 25-hydroyvitamin D, +14·5% (P=0·0051); parathyroid hormone (PTH), −12·3% (P=0·0011); CTX, −7·5% (P=0·01); tartrate-resistant acid phosphatase isoform 5b (TRAP 5b), −9·9% (P<0·0001); albumin, +6·2% (P<0·0001); insulin-like growth factor-I (IGF-I),+16·9% (P<0·0001); osteocalcin, +8·3% (P=0·0166); amino-terminal propeptide of type 1 procollagen (P1NP),+19·3% (P=0·0031). The present open trial suggests that fortified soft plain cheese consumed by elderly women with vitamin D insufficiency can reduce bone resorption markers by positively influencing Ca and protein economy, as expressed by decreased PTH and increased IGF-I, respectively. The rise in the bone formation marker P1NP could be explained by a protein-mediated increase in IGF-I. Thus, such a dietary intervention might uncouple, at least transiently, bone resorption from bone formation and thereby attenuate age-related bone los

Internal stresses analysis on welded joint in Grade 91 steel under creep test: synchrotron DRX tests and modelling

The analysis and understanding of creep damage of Grade 91 steel welded joints is an important topic in the energy industry. Creep tests on welded joints were carried out at 600$^{\circ}$C, 100MPa and then interrupted at 0%, 10%, 30%, 50%, 80% of the expected life and after failure. Creep damage is characterised by cavity bands located exclusively in the core of the sample in the InterCritical Heat Affected Zone (ICHAZ). These samples were tested using \textit{in situ} synchrotron XRD along the welded joint under creep conditions for the different creep life time. The experimental results show a significant strain evolution and creep damage characteristic on the welded joint, with a local maximum at the Heat Affected Zone (HAZ). Following this, a finite element creep strain analysis was performed for comparison with the experimental results.Comment: 19 pages, 11 figure

High and low molecular weight crossovers in the longest relaxation time dependence of linear cis-1,4 polyisoprene by dielectric relaxations

The dielectric relaxation of cis-1,4 Polyisoprene [PI] is sensitive not only to the local and segmental dynamics but also to the larger scale chain (end-to-end) fluctuations. We have performed a careful dielectric investigation on linear PI with various molecular weights in the range of 1 to 320 kg/mol. The broadband dielectric spectra of all samples were measured isothermally at the same temperature to avoid utilizing shift factors. For the low and medium molecular weight range, the comparisons were performed at 250 K to access both the segmental relaxation and normal mode peaks inside the available frequency window (1 mHz–10 MHz). In this way, we were able to observe simultaneously the effect of molecular mass on the segmental dynamics—related with the glass transition process—and on the end-to-end relaxation time of PI and thus decouple the direct effect of molecular weight on the normal mode from that due to the effect on the monomeric friction coefficient. The latter effect is significant for low molecular weight (M w < 33 kg/mol), i.e., in the range where the crossover from Rouse dynamics to entanglement limited flow occurs. Despite the conductivity contribution at low frequency, careful experiments allowed us to access to the normal mode signal for molecular weights as high as M w = 320 kg/mol, i.e., into the range of high molecular weights where the pure reptation behavior could be valid, at least for the description of the slowest chain modes. The comparison between the dielectric relaxations of PI samples with medium and high molecular weight was performed at 320 K. We found two crossovers in the molecular weight dependence of the longest relaxation time, the first around a molecular weight of 6.5 ± 0.5 kg/mol corresponding to the end of the Rouse regime and the second around 75 ± 10 kg/mol. Above this latter value, we find a power law compatible with exponent 3 as predicted by the De Gennes theory

Gonad-related factors promote muscle performance gain during postnatal development in male and female mice

To better define the role of male and female gonad-related factors (MGRF, presumably testosterone, and FGRF, presumably estradiol, respectively) on mouse hindlimb skeletal muscle contractile performance/function gain during postnatal development, we analyzed the effect of castration initiated before puberty in male and female mice. We found that muscle absolute and specific (normalized to muscle weight) maximal forces were decreased in 6-mo-old male and female castrated mice compared with age- and sex-matched intact mice, without alteration in neuromuscular transmission. Moreover, castration decreased absolute and specific maximal powers, another important aspect of muscle performance, in 6-mo-old males, but not in females. Absolute maximal force was similarly reduced by castration in 3-mo-old muscle fiber androgen receptor (AR)-deficient and wild-type male mice, indicating that the effect of MGRF was muscle fiber AR independent. Castration reduced the muscle weight gain in 3-mo mice of both sexes and in 6-mo females but not in males. We also found that bone morphogenetic protein signaling through Smad1/5/9 was not altered by castration in atrophic muscle of 3-mo-old mice of both sexes. Moreover, castration decreased the sexual dimorphism regarding muscle performance. Together, these results demonstrated that in the long term, MGRF and FGRF promote muscle performance gain in mice during postnatal development, independently of muscle growth in males, largely via improving muscle contractile quality (force and power normalized), and that MGFR and FGRF also contribute to sexual dimorphism. However, the mechanisms underlying MGFR and FGRF actions remain to be determined