Philosophie des mathematiques et formation des professeurs stagiaires

In this article, through the analysis of teachers training sessions and questionnaires about teachers’ and students’ representations, we present one of the didactic issues of an epistemological training. Teachers’ epistemological views are not only of a platonic type. They are numerous and deeply anchored. Teachers’ representations are generally in agreement with students’ views on mathematics but sometimes, on some specific aspects, they enter in contradiction with them. In these cases, education in philosophy and history of sciences can be helpful in allowing teachers to become conscious that beyond knowledge, they impart a certain vision of mathematics and science

Comparative study of rans turbulence models for impinging jet simulations

Impinging plane jets are flow configurations with applications in many fields. The ability of several turbulence models to simulate this kind of flow was assessed. The numerical results were compared with the data of Cooper et al. (1993) for Re=7.0 104 and a jet nozzle aspect ratio H/D=6, and Re=2.3 104 and H/D=2. The SST, RSM-ε and RSM-BSL turbulence models were chosen because of their capability to predict flows with high streamline curvature and their expected good accuracy on near wall flow. The results show that the SST and RSM- ε perform better than the RSM-BSL in the prediction of the mean velocity profiles in the wall-jet and impact zone. The profiles of turbulent energy were particularly difficult to reproduce. All the turbulence models considered here exhibit a similar behavior with respect to the profiles of turbulent energy. The paper shows again the complexity of turbulent impinging jets and the relevant open challenges in CF

Comparative study of rans turbulence models for impinging jet simulations

Impinging plane jets are flow configurations with applications in many fields. The ability of several turbulence models to simulate this kind of flow was assessed. The numerical results were compared with the data of Cooper et al. (1993) for Re=7.0 104 and a jet nozzle aspect ratio H/D=6, and Re=2.3 104 and H/D=2. The SST, RSM-ε and RSM-BSL turbulence models were chosen because of their capability to predict flows with high streamline curvature and their expected good accuracy on near wall flow. The results show that the SST and RSM- ε perform better than the RSM-BSL in the prediction of the mean velocity profiles in the wall-jet and impact zone. The profiles of turbulent energy were particularly difficult to reproduce. All the turbulence models considered here exhibit a similar behavior with respect to the profiles of turbulent energy. The paper shows again the complexity of turbulent impinging jets and the relevant open challenges in CF

The influence of different types of preparation (espresso and brew) on coffee aroma and main bioactive constituents

Coffee is one of the most popular hot drinks in the world; it may be prepared by several methods, but the most common forms are boiled (brew) and pressurized (espresso). Analytical studies on the substances responsible for the pleasant aroma of roasted coffee have been carried out for more than 100 years. Brew coffee and espresso coffee (EC) have a different and peculiar aroma profile, demonstrating the importance of the brewing process on the final product sensorial quality. Concerning bioactive compounds, the extraction mechanism plays a crucial role. The differences in the composition of coffee brew in chlorogenic acids and caffeine content is the result of the different procedures of coffee preparation. The aim of the present review is to detail how the brewing process affects coffee aroma and composition

GaN LNAs for Robust Receiving Systems in Radar and Space Applications

In this contribution a series of integrated circuits and methodologies, purposely developed for application in microwave receiving subsystems, will be presented. The integrated circuits, realized in GaN integrated technologies by different suppliers, find their applications in telecom systems as well as in RADAR ones, mainly for space-based apparatuses. The respective performance, as well as the key design methods will be presented in the contribution for bandwidths ranging from S-Band up to K-Band

Correction to: Quality traits of raw and cooked cupped oysters

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Interface-resolved direct numerical simulations of sediment transport in a turbulent oscillatory boundary layer

The flow within an oscillatory boundary layer, which approximates the flow generated by propagating sea waves of small amplitude close to the bottom, is simulated numerically by integrating the Navier-Stokes and continuity equations. The bottom is made up of spherical particles, free to move, which mimic sediment grains. The approach allows one to fully resolve the flow around the particles and to evaluate the forces and torques that the fluid exerts on their surface. Then, the dynamics of sediments is explicitly computed by means of the Newton-Euler equations. For the smallest value of the flow Reynolds number presently simulated, the flow regime turns out to fall in the intermittently turbulent regime such that turbulence appears when the free-stream velocity is close to its largest value but the flow recovers a laminar-like behaviour during the remaining phases of the cycle. For the largest value of the Reynolds number, turbulence is significant during almost the whole flow cycle. The evaluation of the sediment transport rate allows one to estimate the reliability of the empirical predictors commonly used to estimate the amount of sediments transported by sea waves. For large values of the Shields parameter, the sediment flow rate during the accelerating phases does not differ from that observed during the decelerating phases. However, for relatively small values of the Shields parameter, the amount of moving particles depends not only on the bottom shear stress but also on flow acceleration. Moreover, the numerical results provide information on the role that turbulent eddies have on sediment dynamics

Practical manual on geographical indications for ACP countries

Geographical indications (GIs), which link the quality/reputation of a product to a given location, can contribute to enhancing the value of local products. This manual assists producers and policy-makers who are interested in acquiring the basic knowledge needed to embark on the ‘GI adventure’. Intended to be understood by non-specialists, the text explores the key issues concerning GIs, placing specific emphasis on the interests and needs of ACP countries. For those who want to find out more, references are provided to more specialised and detailed publications

Manuel pratique sur les indications géographiques pour les pays ACP

Les indications géographiques (IG), qui associent la qualité et la réputation d'un produit à un endroit donné, peuvent contribuer à l'amélioration de la valeur des produits locaux. Ce manuel aide les producteurs et les décideurs désireux d'acquérir les connaissances de base nécessaires pour se lancer dans « l'aventure IG ». Destiné à être compris par des non-spécialistes, le texte explore les questions clé concernant les IG, en mettant particulièrement l'accent sur les intérêts et les besoins des pays ACP. Pour ceux qui veulent en savoir plus, des références renvoient à des publications plus spécialisées et plus détaillées