Analysis and Comparison of Transonic Buffet Phenomenon over Several Three-Dimensional Wings

International audienceThe transonic buffet is a complex aerodynamic instability that appears on wings and airfoils at a high subsonic Mach number and/or angle of attack. It consists of a shock oscillation that induces pressure and notably lift fluctuations, thus limiting the flight envelope of civil aircraft. The aim of the present Paper is to improve the understanding of the flow physics of the three-dimensional transonic buffet over swept wings through the analysis and comparison of four different experimental databases. In particular, the objective is to identify characteristic values of the phenomenon such as Strouhal numbers, convection velocities, buffet onset, etc. It is shown that some dimensionless numbers are kept constant among the different databases and consequently can be considered as characteristics, whereas others change. The key factors in the understanding of the three-dimensional transonic buffet phenomenon lie in explaining common features but also the variability of transonic buffet characteristics in different configurations. In particular, it is shown that three-dimensional buffet is characterized by a Strouhal number in the range 0.2–0.3 and a spanwise convection velocity of 0.245 0.015 U∞, where U∞ denotes the freestream velocity. These characteristic ranges of frequencies are larger than those of the two-dimensional buffet phenomenon, which suggests different physical mechanisms

SERVice Oriented Intelligent Value Adding nEtwork for Clothing-SMEs embarking in Mass-Customisation [as a result of the Automatic knitting Sites pilot, Task D6.2a]. CORDIS.

Executive Summary: This report describes the outcomes of research and development work done by IFTH (France) and Nottingham Trent University (UK) to develop and evaluate the procedures for a business model to produce commercially customised fully-fashioned knitwear. It builds on the initial work done by Unicatum, RWTH and Hohenstein Institute (Germany). The purpose was to demonstrate the commercial potential for on-demand, localised manufacturing of up-market fashion products using new technology. The target market was upper-middle market knitwear for ladies, typical products being a jumper, cardigan or dress. As with the rest of the SERVIVE project, customisation has been assumed to be linked to style advice. Thus part of the overall product and consumer experience is the initial process of co-design. This is partly illustrated in the video of the demonstration [see http://www.youtube.com/watch?v=WIodKyciJAM]. However as this could vary according to each retailer (e.g. web-based or personal style advisor, product category, etc.), this aspect is better covered in other SERVIVE project deliverables. The key technology assumed in the micro-factory is one or more whole-garment 3D knitting machines. It is recognised that this can be an option with circular knitting (e.g. Santoni), but in this instance the focus is on the multiple flat-bed technology such as is available from Stoll and Shima Seiki

Thermo-mechanical behaviour of a compacted swelling clay

Compacted unsaturated swelling clay is often considered as a possible buffer material for deep nuclear waste disposal. An isotropic cell permitting simultaneous control of suction, temperature and pressure was used to study the thermo-mechanical behaviour of this clay. Tests were performed at total suctions ranging from 9 to 110 MPa, temperature from 25 to 80 degrees C, isotropic pressure from 0.1 to 60 MPa. It was observed that heating at constant suction and pressure induces either swelling or contraction. The results from compression tests at constant suction and temperature evidenced that at lower suction, the yield pressure was lower, the elastic compressibility parameter and the plastic compressibility parameter were higher. On the other hand, at a similar suction, the yield pressure was slightly influenced by the temperature; and the compressibility parameters were insensitive to temperature changes. The thermal hardening phenomenon was equally evidenced by following a thermo-mechanical path of loading-heating-cooling-reloading

Water level fluctuations in the Congo basin derived from ENVISAT satellite altimetry

In the Congo Basin, the elevated vulnerability of food security and the water supply implies that sustainable development strategies must incorporate the effects of climate change on hydrological regimes. However, the lack of observational hydro-climatic data over the past decades strongly limits the number of studies investigating the effects of climate change in the Congo Basin. We present the largest altimetry-based dataset of water levels ever constituted over the entire Congo Basin. This dataset of water levels illuminates the hydrological regimes of various tributaries of the Congo River. A total of 140 water level time series are extracted using ENVISAT altimetry over the period of 2003 to 2009. To improve the understanding of the physical phenomena dominating the region, we perform a K-means cluster analysis of the altimeter-derived river level height variations to identify groups of hydrologically similar catchments. This analysis reveals nine distinct hydrological regions. The proposed regionalization scheme is validated and therefore considered reliable for estimating monthly water level variations in the Congo Basin. This result confirms the potential of satellite altimetry in monitoring spatio-temporal water level variations as a promising and unprecedented means for improved representation of the hydrologic characteristics in large ungauged river basins

Expansion of elevational range in a forest pest: Can parasitoids track their hosts?

We are thankful to Karim Senhadji and Ramon Ruiz-Puche for their help during the field work, and to Sara Garcia Morato for her contribution to quantifying rates of parasitism in PPM clutches at the laboratory. Two anonymous referees contributed to improve the manuscript. This study was supported by projects PROPINOL (PN22/2008), GESBOME (P06-RNM-1890) from Junta de Andalucia, REMEDINAL TE-CM (S2018/EMT-4338) from Comunidad de Madrid, ADAPTAMED (LIFE14 CCA/ES/000612) from LIFE program, and GILES (PCIN-2016-150) from the ERANET-LAC H2020 Programme.Gradients in elevation impose changes in environmental conditions, which in turn modulate species distribution and abundance as well as the interactions they maintain. Along the gradient, interacting species (e.g., predators, parasitoids) can respond to changes in different ways. This study aims to investigate how egg parasitism of a forest pest, the pine processionary moth (PPM), Thaumetopoea pityocampa, vary along an elevational gradient (190-2000 m.a.s.l.) in a mountain range of SE Spain, including areas of recent elevational expansion, for a seven years period (2008-2014). We used generalized linear mixed models to ascertain the effect of both elevation and the winter North Atlantic Oscillation (NAO) index (a proxy of interannual climatic conditions) on the rate of parasitism, and the occurrence probabilities of two parasitoid species: a PPM specialist and a generalist species. Since four pine species are stratified along the elevational gradient, we repeated all the analyses separately for lowlands (190-1300 m. a.s.l.) and uplands (1350-2000 m. a.s.l.). Results showed a decrease in both parasitism rate and probability of occurrence of the two main parasitoid species with elevation, although decline was more severe for the specialist species. The effect of elevation was more conspicuous and intense in uplands than in lowlands. Positive NAO winter values, associated with cold and dry winters, reduced the rate of parasitism and the probability of occurrence of the two main parasitoid species-but particularly for the generalist species-as elevation increases. In a context of climate warming, it is crucial to mitigate PPM elevational and latitudinal expansion. Increasing tree diversity at the PPM expansion areas may favor the establishment of parasitoids, which could contribute to synchronizing host- parasitoid interactions and minimize the risk of PPM outbreaks.Junta de Andalucia PN22/2008REMEDINAL TE-CM from Comunidad de Madrid S2018/EMT-4338ADAPTAMED from LIFE program LIFE14 CCA/ES/000612GILES from the ERANET-LAC H2020 Programme PCIN-2016-150Junta de Andalucia P06-RNM-189

First LIGO search for gravitational wave bursts from cosmic (super)strings

We report on a matched-filter search for gravitational wave bursts from cosmic string cusps using LIGO data from the fourth science run (S4) which took place in February and March 2005. No gravitational waves were detected in 14.9 days of data from times when all three LIGO detectors were operating. We interpret the result in terms of a frequentist upper limit on the rate of gravitational wave bursts and use the limits on the rate to constrain the parameter space (string tension, reconnection probability, and loop sizes) of cosmic string models.Comment: 11 pages, 3 figures. Replaced with version submitted to PR

The Scientific Performance of the Microchannel X-ray Telescope on board the SVOM Mission

The Microchannel X-ray Telescope (MXT) will be the first focusing X-ray telescope based on a "Lobster-Eye" optical design to be flown on Sino-French mission SVOM. SVOM will be dedicated to the study of Gamma-Ray Bursts and more generally time-domain astrophysics. The MXT telescope is a compact (focal length ~ 1.15 m) and light (< 42 kg) instrument, sensitive in the 0.2--10 keV energy range. It is composed of an optical system, based on micro-pore optics (MPOs) of 40 micron pore size, coupled to a low-noise pnCDD X-ray detector. In this paper we describe the expected scientific performance of the MXT telescope, based on the End-to-End calibration campaign performed in fall 2021, before the integration of the SVOM payload on the satellite.Comment: 22 pages, 12 figures, accepted for publication in Experimental Astronom