Impacts of the IUCN Red List of Ecosystems on conservation policy and practice

In 2014, the International Union for Conservation of Nature adopted the Red List of Ecosystems (RLE) criteria as the global standard for assessing risks to terrestrial, marine, and freshwater ecosystems. Five years on, it is timely to ask what impact this new initiative has had on ecosystem management and conservation. In this policy perspective, we use an impact evaluation framework to distinguish the outputs, outcomes, and impacts of the RLE since its inception. To date, 2,821 ecosystems in 100 countries have been assessed following the RLE protocol. Systematic assessments are complete or underway in 21 countries and two continental regions (the Americas and Europe). Countries with established ecosystem policy infrastructure have already used the RLE to inform legislation, land-use planning, protected area management, monitoring and reporting, and ecosystem management. Impacts are still emerging due to varying pace and commitment to implementation across different countries. In the future, RLE indices based on systematic assessments have high potential to inform global biodiversity reporting. Expanding the coverage of RLE assessments, building capacity and political will to undertake them, and establishing stronger policy instruments to manage red-listed ecosystems will be key to maximizing conservation impacts over the coming decades

Small nomadic counter-rotating wind turbine : design and experimentation

International audienc

Depowdering of lattice structures manufactured by Electron Beam Melting

National audienceAfter completing a part in Electron Beam Melting (EBM), a depowdering operation is required to separate the sintered but unmelted powder from the manufactured part. Depowdering lattice structures can be difficult or even impossible due to their intrinsic shape. The aim of this paper is to propose a criterion to ensure that a lattice structure manufactured by EBM can be depowdered. The objective is to use this criterion during the design phase of lattice structure to design manufacturable and depowderable parts. Experiments are conducted on depowdering octet-truss lattice structures with variable bars thickness and mesh size. Different criteria are introduced, among them the criterion "hydraulic diameter" of a lattice structure, inspired by the Darcy-Weisbach hydraulic law used to calculate the pressure drop in a pipe. This criterion can be determined using geometrical characteristics of the lattice structures available in the CAD model of the part. Results show that the levels of depowdering for the lattice structures are proportional to this criterion

Innovative blade shape for micro wind turbines

International audienceThis study reports the design and fabrication of innovative blades for a centimeter-scale propeller and the experimental testing of a wind harvester. A samara wing structure is taken as a model to optimize the aerodynamics at low Reynolds number. The performances of the 44 mm diameter horizontalaxis micro wind turbine are tested in two dedicated wind tunnels, with wind speeds from 1.2 m.s$^{−1 }$to 8 m.s$^{−1 }$. The output electrical powers range from 50 µW to 80 mW, with a maximal overall efficiency of 17.5% for 4 m.s$^{−1 }$. It appears that this bioinspired prototype have better performances than almost all the previous studies on small-scale wind harvesters in a large wind speeds range, and gives hope to get even higher

Extending the operating limits and performances of centimetre-scale wind turbines through biomimicry

International audienceThis paper reports the design and fabrication of an innovative small-size propeller and its experimental testing once assembled with an electromagnetic generator. The bioinspired rotor is based on the shape and behaviour of maple samaras that optimise the aerodynamics at low Reynolds numbers. To the authors’ knowledge, it is the first samara-based wind energy harvester reported to date and one of the smallest wind turbines in the literature. The different blade angles and the number of propeller blades are optimised. A permanent magnet miniature generator with low friction ceramic bearings is used to convert rotation into electrical power. The performance of this 44 mm diameter horizontal-axis wind turbine is tested under wind speeds from 1.2 to 8 m.s-1. The output electrical power measured in resistive load is between 41 µW and 81.7 mW, which leads to an overall efficiency between 2.6 (1.2 m.s−1) and 17.8% (4 m.s−1). Estimates of different losses in the harvester make it possible to determine power coefficient Cp which reaches 28.4%. Among the miniature wind turbines in the literature, this device demonstrates one of the highest rates in terms of efficiency and power density. Moreover, thanks to its operating speed decreased to 1.2 m.s−1 – the lowest in the state of the art – it presents one of the largest ranges of airspeeds for energy harvesting

Extending the operating limits and performances of centimetre-scale wind turbines through biomimicry

International audienceThis paper reports the design and fabrication of an innovative small-size propeller and its experimental testing once assembled with an electromagnetic generator. The bioinspired rotor is based on the shape and behaviour of maple samaras that optimise the aerodynamics at low Reynolds numbers. To the authors’ knowledge, it is the first samara-based wind energy harvester reported to date and one of the smallest wind turbines in the literature. The different blade angles and the number of propeller blades are optimised. A permanent magnet miniature generator with low friction ceramic bearings is used to convert rotation into electrical power. The performance of this 44 mm diameter horizontal-axis wind turbine is tested under wind speeds from 1.2 to 8 m.s-1. The output electrical power measured in resistive load is between 41 µW and 81.7 mW, which leads to an overall efficiency between 2.6 (1.2 m.s−1) and 17.8% (4 m.s−1). Estimates of different losses in the harvester make it possible to determine power coefficient Cp which reaches 28.4%. Among the miniature wind turbines in the literature, this device demonstrates one of the highest rates in terms of efficiency and power density. Moreover, thanks to its operating speed decreased to 1.2 m.s−1 – the lowest in the state of the art – it presents one of the largest ranges of airspeeds for energy harvesting

A method to determine the depowdered height in lattices manufactured by electron beam melting

International audienc

Comparison of samaras movement between free falls and constrained rotation, using high speed imaging and stereocorrelation

International audienceThe maple seed, or samara, presents a relatively stable rotational movement after a transitional phase, that allows it to create a high lift and therefore promotes dissemination. This important lift force comes from little vortex created close to the wing, thanks to its shape. This phenomenon is also present for birds and insects. It leads to a spin velocity of samaras between 80 and 150 rad.s-1 and a descending velocity of around 1 m.s-1. The center of rotation approximately coincides with the center of gravity for maple seeds, and it has been observed that this center describes a helical descending movement; it is also the case for mechanical resin samaras. In the study presented here, the behavior of samaras (Acer palmatum) during their free fall was analyzed, in order to valid their characteristic parameters (spin velocity and descending velocity). Then, samaras were placed in a wind tunnel with their axis of rotation xed, and their translation movement stopped. They could always auto-adapt their angular position to the air flow. The relative air speed in the tunnel has been set at the value measured during free falls, to compare the two behaviors. Stereocorrelation has been used with high speed cameras because of the speed of movement (several revolutions per second). The velocities of each point of the samaras were measured by stereo image correlation. Then, from this velocity field, the instantaneous center of rotation, rotation vector and velocity vector of the seeds were identied by optimization considering a rigid body motion. During the free fall experiments, due to the limited depth of field of the objectives, only a quarter of a revolution could be exploited. Whereas in the constrained tests, the samaras are horizontally stable, so their whole movement is in the depth of field. Finally, the differences of movement characteristics between the two setups have been analyzed, to see if a biomimicry application could be valuable for energy harvesting

La restauration écologique en mer : analyse sémantique, concepts associés et stratégies d’intervention

Le concept de restauration écologique devient prédominant dans les politiques liées à l'environnement sans qu'il ne soit défini de façon consensuelle. Le Règlement européen sur la restauration de la nature adopté en 2024 ajoute une portée juridique à la restauration. De plus, il implique pour chaque Etat membre de restaurer de vastes surfaces d’habitats. Afin de proposer un cadrage conceptuel pour la mise en œuvre du Règlement restauration, ce rapport donne une définition complète de la restauration et clarifie les concepts qui lui sont liés. Pour cela, nous avons analysé les définitions de la « restauration » proposées par le Règlement restauration, par des organismes de référence en Ecologie et par des publications scientifiques. Notre étude s’intéresse en particulier à la restauration des écosystèmes marins, elle est cependant en grande partie transposable à tout type d’écosystème.Notre analyse souligne que des variations sémantiques et conceptuelles existent autour de la restauration, en particulier sur les composantes de l’écosystème ciblées par la restauration ainsi que sur la catégorisation des stratégies d’intervention. Nous retenons que la restauration se distingue d’autres concepts par son objectif de viser la récupération de l’ensemble des composantes d’un écosystème ayant subi des dégradations. En termes de méthode, nous préconisons de qualifier les stratégies d’intervention selon un gradient d'intensité et de s’éloigner de la traditionnelle distinction entre restauration « passive » et « active ». Le choix de l’intensité d’intervention dépendra de l'état initial de l'écosystème et de l'état final souhaité.Le cadre conceptuel proposé dans ce rapport a pour finalité d'accompagner les acteurs de l'environnement dans la mise en place du Règlement restauration au niveau national, en favorisant la compréhension commune de ce qu’est la restauration et des concepts associés