Somfy (France)

This paper describes an EMC model in the frequency domain suitable for a DC-DC converter operating in Discontinuous Conduction Mode. In comparison to Continuous Conduction Mode, an additional phase appears, with voltage oscillations, which must be considered. The frequency model is presented and its implementation using LT Spice is described. It is validated in comparison with time domain simulations and measurements, for the application of a roller shutter. Finally, a fine tuning of the EMC model parameters is also presented for the industrial implementation of the converter.

Habitat anthropization is a major driver of global biodiversity decline. Although most species are negatively affected, some benefit from anthropogenic habitat modifications by showing intriguing life-history responses. For instance, increased recruitment through higher allocation to reproduction or improved performance during early-life stages could compensate for reduced adult survival, corresponding to "compensatory recruitment". To date, evidence of compensatory recruitment in response to habitat modification is restricted to plants, limiting understanding of its importance as a response to global change. We used the yellow-bellied toad (Bombina variegata), an amphibian occupying a broad range of natural and anthropogenic habitats, as a model species to test for and to quantify compensatory recruitment. Using an exceptional capture-recapture dataset composed of 21,714 individuals from 67 populations across Europe, we showed that adult survival was lower, lifespan was shorter, and actuarial senescence was higher in anthropogenic habitats, especially those affected by intense human activities. Increased recruitment in anthropogenic habitats fully offset reductions in adult survival, with the consequence that population growth rate in both habitat types was similar. Our findings indicate that compensatory recruitment allows toad populations to remain viable in human-dominated habitats and might facilitate the persistence of other animal populations in such environments.

Objectif: Cette étude vise à évaluer le rôle des espaces verts dans la préservation de la biodiversité dans le district d’Abidjan (Côte d’Ivoire). Les fourmis ont été utilisées comme des indicateurs biologiques afin d’examiner l’influence des activités anthropiques sur la biodiversité de ces habitats localisés dans la matrice urbaine.Méthodologie et résultats: Les fourmis ont été collectées à l’aide d’appât de thon et du protocole ALL (pièges fosses et Winkler) dans trois types d’espaces verts (espaces verts publics, jardins botaniques et le Parc National du Banco). Les résultats indiquent que les espaces verts sont pollués (pourcentage de nuisance compris entre 1,7 % et 28,8 %) et illégalement occupés (pourcentage d’occupation compris entre 1,08 % à 52,3 %) par les activités humaines. Ces milieux abritent toutefois une faune de fourmis riche avec 176 espèces collectées. De plus, les jardins botaniques et les espaces verts publics partagent 8,51 % et 42,55 % des espèces de fourmis avec le Parc National du Banco, malgré leur faible connectivité à cet habitat naturel.Conclusion et application: Cette étude suggère que les espaces verts du district d’Abidjan présentent des atouts de conservation de la biodiversité, en particulier les fourmis. Toutefois, l’occupation de ces milieux par les activités commerciales conduit à leur dégradation progressive et à la disparition des communautés animales et végétales. Les résultats de cette étude devraient interpeller les décideurs à définir une politique de gestion des espaces verts et parcs urbains afin de rehausser leur valeur de conservation de la biodiversité en ville.Mots clés: Espaces verts urbains, conservation, biodiversité, fourmis, Abidjan, Côte d’IvoireEnglish Title: Green areas as an alternative of biodiversity conservation in cities: the case of ants (Hymenoptera: Formicidae) in the district of Abidjan (Côte d’Ivoire)English AbstractObjective: This study aims to assess the role of green areas to preserve biodiversity in the district of Abidjan (Côte d’Ivoire). Ants were used as biological indicators in order to examine the influence of anthropogenic activities on biodiversity of these habitats located in urban matrix.Methodology and results: Ants were sampled using tuna bait, ALL Protocol (Pitfalls and Winklers) in three types of green areas (Public green areas, Botanical Gardens and Banco National Park) under two categories of anthropogenic disturbance. Results indicate a strong pollution rate (between 1.7 % and 28.8 %) and a high percentage of illegal occupation (between 1.08% and 52.3%).. These areas shelter a rich ant fauna with 176 species collected. In addition, Botanical garden and public green areas share 8.51 % to 42.55 % of ant species with Banco National Park, although they are not strongly connected.Conclusion and application: This study suggests that the green areas of the Abidjan district have biodiversity conservation assets, especially for ants. However, the illegal occupation of these areas by commercial activities leads to their progressive degradation and the disappearance of animal and plant communities. The results of this study should challenge decision-makers to define a management policy for green areas and urban parks in order to enhance their conservation value of biodiversity in city.Keywords: Urban green areas, conservation, biodiversity, ants, Abidjan, Côte d’Ivoire

Several complex mechanisms can be responsible for undesirable friction-induced vibrations in many mechanical systems. This paper presents a tribological and dynamic analysis of the stick-slip problem, under greased lubrication, taking into account the practical application of a spring-brake system used in electric tubular motors. The main functioning of these brakes is based on the frictional greased contact between a stationary cylinder and a torsional spring, which rotates inside it. The identification of the parameters that most affect the stick-slip appearance in greased contacts requires a complete understanding and appropriate analysis of the entire system, to identify the effects of all physical parameters on the system. Here the global dynamics and the local contact behaviour is analysed, providing an in-depth examination of the stick-slip phenomenon on a greased contact.

This article deals with the optimization of a single-phase permanent capacitor induction machine according to the criterion of gross energy requirement. The presented study is applied to roller shutter drives produced by SOMFY. These motors present low ratio between the operating time and the total time of use. Therefore, they are perfect candidates for an optimized eco-design method by minimizing the gross energy requirement. As the studied motors are in roller shutter's tubes whose diameter is fixed by production and distribution constraints, only two free parameters are available for our optimizations: the active length and number of turns per phase. In this paper, the size of the motors is optimized in a transient thermal regime. The optimizations are based on a typical operating cycle of roller shutter. It is noticed that the part of the energy required for production and recycling is significant in the gross energy requirement. Thus, the usual optimization focused on the only operating losses is inefficient for this typical operating cycle. This conclusion is validated when existing motors specifications are used as parameters for the optimization. The sensitivity of optimization results are evaluated with respect to both the diameter scale and operating cycle. When the solution are optimal, it appears that an increase of the diameter reduce the gross energy requirement. Another main result is that the operating cycle definition is fundamental in the design of the motor. It justifies the principle of on-cycle optimization.

Abstract The effect of stocking rate on the species richness, abundance and functional diversity of vascular plants, butterflies and grasshoppers was examined in a semi‐natural upland pasture in central France. Over a 5‐year period, 3·6‐ha plots were continuously grazed by Charolais heifers at 1·4 (High stocking rate), 1·0 (Intermediate) and 0·6 (Low) livestock units (LU) ha−1. To evaluate botanical diversity, percentage cover of all plant species was estimated in late July in ten fixed 1 m × 1 m quadrats per plot. Butterflies were counted on three occasions between late June and early August along three fixed 50‐m‐long transects per plot using the ‘Pollard walk’, with grasshoppers being recorded on two occasions along the same transects. Diversity patterns of the three taxa were affected by stocking rate. For plants, species abundance changed more than species number. Abundance of forbs became higher under the Low compared with the High stocking rate. Stress‐tolerant grasses were also more abundant in plots grazed at the Low stocking rate, while an opposite trend was observed for competitive grasses. Butterflies consistently responded to alterations in vegetation composition, especially to the dynamics of nectar plants. The species richness of grasshoppers also increased in plots at the Low stocking rate. The Low and Intermediate stocking rates were suitable for providing a high diversity of the three taxonomic groups. The results suggested that at least butterfly diversity would peak in vegetation taller than that of vascular plants.