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Though compact polarimetric approaches have been developed and applied in space and geo researching systems they have not been taken into consideration in automotive applications, yet. A sensor system has been designed to conduct polarimetric measurements in the 77 GHz frequency band, which is permitted for automotive usage. This system is able to transceive linearly as well as circularly polarized electromagnetic continuous waves. Depending on the case of application, the frequency output can be set statically or modulated over time within adjustable parameters. Hence, a variety of compact polarimetric modes can be performed and compared with full polarimetric approaches. Two compact polarimetric modes, dual-circular polarimetric mode, and circular-transmit-linear-receive, will be introduced and applied in this contribution. Their operability in this frequency range will be investigated after the microstrip antennas as well as the beam focusing dielectrical lense are characterized. Finally, results of a realistical measurement set-up will confirm the practicability of compact polarimetric approaches for double bounce recognition.
G4 alloys (Ti51Al47Re1W1Si0.2) are developed by Spark Plasma Sintering (SPS) with the aim to improve the creep resistance of SPS materials. The microstructure is analyzed by Scanning and Transmission Electron Microscopies (SEM and TEM). The mechanical properties at low and high temperatures are measured. The addition of heavy elements does not lead to an improvement of the mechanical strength.
Control of laminar-to-turbulent transition on a swept-wing is achieved by base-flow modification in an experimental framework, up to a chord Reynolds number of 2.5 million. This technique is based on the control strategy used in the numerical simulation by Dörr & Kloker (J. Phys. D: Appl. Phys., vol. 48, 2015b, 285205). A spanwise uniform body force is introduced using dielectric barrier discharge plasma actuators, to either force against or along the local cross-flow component of the boundary layer. The effect of forcing on the stability of the boundary layer is analysed using a simplified model proposed by Serpieri et al. (J. Fluid Mech., vol. 833, 2017, pp. 164–205). A minimal thickness plasma actuator is fabricated using spray-on techniques and positioned near the leading edge of the swept-wing, while infrared thermography is used to detect and quantify transition location. Results from both the simplified model and experiment indicate that forcing along the local cross-flow component promotes transition while forcing against successfully delays transition. This is the first experimental demonstration of swept-wing transition delay via base-flow modification using plasma actuators.
Fast liquid jets, called micro-jets, are produced within cavitation bubbles experiencing an aspherical collapse. Here we review micro-jets of different origins, scales and appearances, and propose a unified framework to describe their dynamics by using an anisotropy parameter
, representing a dimensionless measure of the liquid momentum at the collapse point (Kelvin impulse). This parameter is rigorously defined for various jet drivers, including gravity and nearby boundaries. Combining theoretical considerations with hundreds of high-speed visualisations of bubbles collapsing near a rigid surface, near a free surface or in variable gravity, we classify the jets into three distinct regimes: weak, intermediate and strong. Weak jets (
) hardly pierce the bubble, but remain within it throughout the collapse and rebound. Intermediate jets (
) pierce the opposite bubble wall close to the last collapse phase and clearly emerge during the rebound. Strong jets (
) pierce the bubble early during the collapse. The dynamics of the jets is analysed through key observables, such as the jet impact time, jet speed, bubble displacement, bubble volume at jet impact and vapour-jet volume. We find that, upon normalising these observables to dimensionless jet parameters, they all reduce to straightforward functions of
, which we can reproduce numerically using potential flow theory. An interesting consequence of this result is that a measurement of a single observable, such as the bubble displacement, suffices to estimate any other parameter, such as the jet speed. Remarkably, the dimensionless parameters of intermediate and weak jets (
) depend only on
, not on the jet driver (i.e. gravity or boundaries). In the same regime, the jet parameters are found to be well approximated by power laws of
, which we explain through analytical arguments.
Based on radiocarbon and optically stimulated luminescence (OSL) results obtained in the last 5 yr, this paper discusses the absolute chronology of the formation of one of the largest sand dunes within NW Belgium, the Great Ridge of Maldegem-Stekene. Multiproxy analysis of 6 sedimentary sequences points to a complex formation history covering the entire Late Glacial. Dry phases, characterized by eolian deflation and sedimentation, alternated with wet phases in which numerous mostly shallow dune slacks were filled with freshwater. The latter reached their highest water level during the first half of the Allerød, attracting both animals (e.g. European elk) and humans (Federmesser hunter-gatherers). Near the end of the Allerød, all dune slacks finally disappeared as they were filled in with windblown sand ("coversand"), likely forcing prehistoric hunter-gatherers to leave the area.
Growth rings of Mesozoic fossil woods have often been used for paleoclimatological inferences. Most of the studies, however, rest upon uniformitarian deductions based on the observation of conifers from the present boreal temperate realm, whereas warm climates dominated during the Mesozoic. We propose a new approach, based on the study of the distribution of growth ring types among 643 samples from the Jurassic-Cretaceous interval. A clear picture emerges from analysis, consistent with what is known of Mesozoic climates from other sources. Woods with no rings are encountered in a wide latitudinal zone, extending up to 75°N and 65°S during the Late Cretaceous. Woods with well-developed latewood do not occur at low latitude and disappeared from the Northern Hemisphere during the Late Cretaceous. Our data set also shows that the taxonomic distribution of growth ring types is not regular. Among the genera encountered, 40% can build only one type of ring. The genus Agathoxylon never displays thick latewood, although it ranges from 75°S to 70°N. This demonstrates that growth ring studies must include a taxonomic analysis.
Patients with pulmonary regurgitation after tetralogy of Fallot repair have impaired aerobic capacity; one of the reasons is the decreasing global ventricular performance at exercise, reflected by decreasing peak oxygen pulse. The aims of our study were to evaluate the impact of pulmonary valve replacement on peak oxygen pulse in a population with pure pulmonary regurgitation and with different degrees of right ventricular dilatation and to determine the predictors of peak oxygen pulse after pulmonary valve replacement.
The mean and median age at pulmonary valve replacement was 27 years. Mean pre-procedural right ventricular end-diastolic volume was 182 ml/m2. Out of 24 patients, 15 had abnormal peak oxygen pulse before pulmonary valve replacement. We did not observe a significant increase in peak oxygen pulse after pulmonary valve replacement (p=0.76). Among cardiopulmonary test/MRI/historical pre-procedural parameters, peak oxygen pulse appeared to be the best predictor of peak oxygen pulse after pulmonary valve replacement (positive and negative predictive values, respectively, 0.94 and 1). After pulmonary valve replacement, peak oxygen pulse was well correlated with left ventricular stroke and end-diastolic volumes (r=0.67 and 0.68, respectively).
Our study confirms the absence of an effect of pulmonary valve replacement on peak oxygen pulse whatever the initial right ventricular volume, reflecting possible irreversible right and/or left ventricle lesions. Pre-procedural peak oxygen pulse seemed to well predict post-procedural peak oxygen pulse. These results encourage discussions on pulmonary valve replacement in patients showing any decrease in peak oxygen pulse during their follow-up.
The effect of protein intake on growth velocity in infancy may be mediated by insulin-like growth factor-1 (IGF-1). This study aimed to determine the effects of formulae containing 1·8 (F1·8) or 2·7 g (F2·7) protein/418·4 kJ (100 kcal) on IGF-1 concentrations and growth. Healthy term infants were randomly assigned to receive F1·8 (n 74) or F2·7 (n 80) exclusively for the first 4 months of life. A group of breast-fed infants (n 84) was followed-up simultaneously (reference). Growth and body composition were measured at 0·5, 4, 6, 12, 36, 48 and 60 months of life. The IGF-1 concentrations at 4 months (primary outcome) were similar in the F1·8 (67·1 (sd 20·8) ng/l; n 70) and F2·7 (71·2 (sd 27·5) ng/l; n 73) groups (P=0·52). Both formula groups had higher IGF-1 concentrations than the breast-fed group at 4 and 9 months of age (P≤0·0001). During the first 60 months of life, anthropometric parameters in the F1·8 group were lower compared with the F2·7 group, and the differences were significant for head circumference from 2 to 60 months, body weight at 4 and 6 months and length at 9, 12 and 36 months of age. There were no significant differences in body composition between these two groups at any age. We conclude that, in formula-fed infants, although increased protein intake did not affect the IGF-1 concentration during the first 12 months of life, it did affect length and head circumference growth, suggesting that factors other than IGF-1 could play roles in determining growth velocity.
Disaster response demands a large workforce covering diverse professional sectors. Throughout this article, we illustrate the results of a systematic review of peer-reviewed studies to identify existing competency sets for disaster management and humanitarian assistance that would serve as guidance for the development of a common disaster curriculum. A systematic review of English-language articles was performed on PubMed, Google Scholar, Scopus, ERIC, and Cochrane Library. Studies were included if reporting competency domains, abilities, knowledge, skills, or attitudes for professionals involved disaster relief or humanitarian assistance. Exclusion criteria included abstracts, citations, case studies, and studies not dealing with disasters or humanitarian assistance. Thirty-eight papers were analyzed. Target audience was defined in all articles. Five references (13%) reported cross-sectorial competencies. Most of the articles (81.6%) were specific to health care. Eighteen (47%) papers included competencies for at least 2 different disciplines and 18 (47%) for different professional groups. Nursing was the most widely represented cadre. Eighteen papers (47%) defined competency domains and 36 (94%) reported list of competencies. Nineteen articles (50%) adopted consensus-building to define competencies, and 12 (31%) included competencies adapted to different professional responsibility levels. This systematic review revealed that the largest number of papers were mainly focused on the health care sector and presented a lack of agreement on the terminology used for competency-based definition. (Disaster Med Public Health Preparedness. 2015;9:430–439)
The spatio-temporal pressure–velocity correlation in a turbulent boundary layer is investigated so as to understand the link between pressure fluctuations and turbulent coherent structures. A new experimental set-up is developed to measure the pressure fluctuations at the wall and in the field and, simultaneously, the velocity field by stereoscopic particle image velocimetry. The present measurement area covers the whole boundary layer thickness, and the spatial resolution of the measurement is good enough to assess the representative length scales of the flow. The Reynolds number effect is quantified from the data at
, 10 000, 18 000. The spatio-temporal three-dimensional structures of the pressure–velocity correlations,
, are evaluated. The wall pressure fluctuations are closely coupled with coherent structures which occupy a large region of the boundary layer in the wall-normal and spanwise directions and up to
in time, where
denote the boundary layer thickness and the free stream velocity. Reynolds number effects are mainly observed on the size and intensity of the pressure–velocity correlations. Conditioning the correlations on the pressure signal sign shows different types of flow phenomena linked to the positive and negative pressure events. For the wall pressure, positive pressure fluctuations appear to be correlated with the leading edge of a large sweeping motion of splatting type followed by a large ejection. The negative pressure fluctuations are linked to a localized ejection upstream, followed by a large sweeping motion downstream. For the pressure fluctuations in the field, in addition to the structures observed with the wall pressure, the pressure–velocity correlations exhibit a significant correlation in a region very extended in time. Such long structures appear to be independent of the one observed at the wall and to grow significantly in time with the Reynolds number when scaling with external variables. When conditioned by the pressure sign, clear ejection and sweeping motions are observed with associated streamwise vortical structures at a scale of the order of
. These structures can be linked to the large-scale motion and very-large-scale motion previously observed by different authors and seem to organize in a scheme analogous to the near-wall cycle, but at a much larger scale.
This work is an overview of the physical approaches required for characterizing and understanding the long-term evolution of ceramics under irradiation. Because this subject is complex and has many ramifications, we have chosen to address the problem by looking at the behavior of a number of key ceramics. In the first part of this work, we present the physical mechanisms responsible for the production of primary defects, pointing out the main differences between metals, semiconductors, and insulators. In part two, we attempt to show how devoted experimental techniques can combine with transmission electron microscopy and x-ray techniques to provide a clearer picture of the long-term evolution of the microstructure of ceramics under irradiation. The last part of this work is devoted to discussing different approaches to explain and describe the long-term behavior of irradiated ceramics.
The aim of this study was to clarify the trophic patterns of the key species Pleuragramma antarctica in the Dumont d’Urville Sea, through its development and possible changes according to sampling locations. Variability in diet composition of larvae, juvenile and adult P. antarctica was analysed using fatty acid markers. Analysis of lipid class in P. antarctica reflected lipid accumulation with increasing size at all sampling stations. The fatty acid composition of triacylglycerol highlighted ontogenetic changes in the diet. Phytoplankton markers, such as C16PUFA:C16 and EPA:DHA ratios >1, and carnivorous markers in larvae suggested an omnivorous diet. Comparison between the fatty acid signature of P. antarctica older stages (juveniles and adults) and zooplankton species using OPLS-discriminant analysis indicated that juveniles fed mainly on euphausiid larvae and to a minor extent on copepods, and confirmed that non-herbivorous copepods were the main prey for adults. Our results suggest that different feeding patterns and a generalist strategy in P. antarctica with juveniles feeding on bigger prey than adults, probably as a result of prey availability according to their vertical segregation pattern.
The aim of this paper is to show that historical technical archives and complementary physico-chemical studies can be combined to obtain relevant information on the materials and processes used in the manufacturing of a Breguet 765 Sahara airplane. This will be useful both in history of sciences and technology and in the renovation of this more than fifty years old airplane.
The Breguet 765 Sahara plane is the last version of a family of French double-deck transport aircraft produced by Breguet between 1948 and 1960. The gathering of multi-disciplinary information from the literature of the period of production with laboratory investigations has revealed that a “new” aluminum-copper-magnesium alloy was used in the rivets of the Breguet 765. The A-U3G alloy was developed to meet properties requirements of the aeronautical industry for joining sheets of aluminum and was used in the Breguet 765 Sahara to strengthen the joints. Analytical techniques included TEM, EPMA microprobe and metallography.
Be stars are B-type stars near the main sequence which undergo episodic mass loss events detected by emission lines, whose line shape and intensity vary with a timescale of the order of decades. Spectroscopic observations show a large rotation velocity such that one of the prevailing scenarios for the formation of the equatorial disk consists in an increasing equatorial rotation velocity to the break-up limit where gravity is challenged by the centrifugal force. We investigate here a new scenario recently suggested by Ishimatsu & Shibahashi (2013), in which the transport of angular momentum through the photosphere would be achieved by leaky waves, keeping the rotation velocity still below the break-up limit.
In order to highlight the genetic status and origin of Moroccan apricot populations, trees were collected from ten oasis agroecosystems and analysed with AFLP markers. A total of 87 accessions and 12 cultivars grown in Moroccan orchards, including ‘Canino’ and ‘Del Patriarca’ cultivars, were surveyed and compared with in situ Tunisian and ex situ Montfavet (France) collections. Our results highlighted a narrow genetic diversity in the Maghreb region (Tunisia and Morocco) associated with a strong differentiation from the other groups, which supports a bottleneck effect. A similar model was illustrated at a finer geographical scale, i.e. the Draa Valley in Morocco. Genetic structure appeared as two major clusters subdivided into six sub-clusters in which Moroccan germplasm constituted specific groups in comparison with other Mediterranean apricots. Moroccan germplasm was classified into three sub-clusters, two of which were formed by genotypes related to ‘Del Patriarca’ and ‘Canino’, respectively. The present study highlights the wide Moroccan apricot's diversity in traditional agroecosystems, and also suggests a substantial gene flow occurring from recently introduced cultivars (‘Canino’ and ‘Del Patriarca’) to local apricot populations, thus leading to local germplasm diversification through seedling propagation. If we consider its geographical position, the historical diffusion of the species and farming practices, Morocco could be viewed as an additional centre of secondary diversification for apricot. Understanding the origin and specificity of local apricot populations is crucial for managing local collections in regard to adaptive traits for arid and Saharan conditions as well as for introducing local genetic resources into current breeding programmes.