Multi-level Policy Coalitions An Interpretative Model Of Water Conflicts ιn The Americas

This article proposes an analytical approach to conflicts and policy-making related to urban water management based on multi-level policy coalitions. This is necessary to articulate four main issues. First, the repositioning of social and political struggles for access to water, along with policy variables. Second, the analysis of the effects of ecological transition, including climate change. Third, the reincorporation of these struggles and challenges in a multi-level approach. Finally, the enquiry into the apparent contradiction, in contemporary policymaking. The article proposes a definition of multi-level coalitions as collective preference systems that influence the content of policies (ideas/advocacy, decisions, policy tools) and their implementation, groups of actors that arise from engagement in policy issues. In the first section, the article presents the objectives of research on urban water management in the Americas, within the framework of which this analytical approach by multi-level coalitions is fashioned. In the second section, the article details four analytical issues. In the third section, it gives a definition of multi-level coalitions.19415317

Significantly less wear of UHMWPE rubbing against pyrocarbon than against CoCr

\ua9 2024 The AuthorsThe history of joint replacement can be framed as a battle to reduce wear. Pyrocarbon has been shown to be a low wear material, but can low wear against an ultra high molecular weight polyethylene (UHMWPE) counterface be achieved? To investigate this research question, a 50-station, clinically validated wear screening machine was used. Half the stations tested UHMWPE pins against pyrocarbon discs, and half the stations tested UHMWPE pins against cobalt chromium (CoCr) discs. The test rig ran at 1Hz, the nominal contact stress was 2.07 MPa, and testing ran to 5 million cycles. A biomimetic lubricant was used, it was replaced every 500,000 cycles. At the end of testing, the UHMWPE pins rubbing against pyrocarbon discs had a statistically significant reduced wear, compared with the UHMWPE pins rubbing against CoCr discs (p ≤ 0.01). Analysis of the discs at the end of testing showed greater adherence of phospholipids on the pyrocarbon discs than the CoCr discs. In turn, it was also seen that far less UHMWPE was attached to the pyrocarbon discs than to the CoCr discs. Based on this evidence, it is suggested that pyrocarbon surfaces are associated with reduced adhesive wear of UHMWPE compared with CoCr surfaces. In addition, at the end of testing, the CoCr discs were found to be significantly rougher than the pyrocarbon discs. Therefore, pyrocarbon maintained a smoother surface than CoCr, likely meaning that abrasive wear of UHMWPE was reduced compared with CoCr

Introduction scientifique

Gilles Massardier (organisateur du colloque), Institut d’Etudes Politiques, ENS, Université Lyon 2, UMR Triangle.National audienc

Aging of an Al-Mg-Si Alloy with a Silicon Excess and Reinforced with Ceramic Particles

International audienc

Over-ageing of an Al-Mg-Si alloy with silicon excess

cited By 0International audienceThe over-ageing of an Al-Mg-Si alloy with Silicon excess was investigated using global thermoelectric power (TEP) and hardness measurements combined with local techniques (Transmission Electron Microscopy (TEM) and Atom Probe Tomography (APT)), in order to highlight how the peak-aged microstructure obtained by a T6 treatment evolves in use conditions at temperatures between 100 °C and 350 °C, leading to a progressive loss of mechanical strength. First, TEP was found to be relevant to study the over-ageing kinetics of the alloy due to its perfect correlation with hardness and its sensitivity to the microstructural changes occurring after peak hardness. Then, APT and TEM observations clearly showed that over-ageing is due to the progressive replacement of the β″ phase by a succession of different types of semi-coherent phases (firstly, of Type B and then of Type A and Type C) and by an extensive precipitation of pure silicon particles. At the highest temperature (T = 350 °C), it was highlighted that the influence of manganese cannot be neglected. From these studies, an experimental Isothermal Transformation Curve could be proposed in the investigated temperature range. Lastly, the decrease in mechanical strength taking place during isothermal and non-isothermal ageing from a T6 state was experimentally characterised and successfully analysed using the JMAK formalism. © 201

Stratégies de traitement collectif des eaux usées et des boues d`épuration : état des lieux et tendances pour les communes du département du Puy-de-Dôme

Basée sur une enquête postale et téléphonique auprès de 471 communes du Puy-de-Dôme (France), l`étude traite des stratégies des communes pour la gestion des eaux usées et des boues. Il ressort de l`étude que le traitement collectif des eaux usées et des boues d`épuration concerne plus des ¾ des communes du Puy-de-Dôme. Entre 1993 et 2003, le nombre de stations d`épuration a doublé pour atteindre 450 unités de traitement des effluents domestiques. Cette évolution récente concerne plutôt les petites communes, les plus grandes municipalités ayant mis en place l`assainissement collectif dès les années soixante-dix. L`épuration des eaux produit en contre partie des boues, dont le volume départemental en 2003 atteint 10 000 tonnes de matières sèches, chaulage compris. Les modes de traitement collectif des eaux usées deviennent de plus en plus conditionnés par le devenir des boues d`épuration. / Based on a mail and phone inquiry with 471 municipalities (Communes) of Puy-de-Dôme (France), the study processes strategies of the municipalities for the management of waste water and sewage sludge. The study shows that collective treatment of water and sewage sludge concerns more of ¾ municipalities of Puy-de-Dôme. Between 1993 and 2003, the number of water-treatment plants has doubled to reach 450 units of treatment of the domestic effluents. This recent evolution concerns rather small municipalities, biggest municipalities having set up the collective purification from the seventies. Water purification produces in counterpart sewage sludge, which local volume in 2003 reaches 10 000 tons of dry materials, included liming. The modes of collective treatment of waste water become more and more conditioned by the future of sewage sludge

Over-ageing of an Al-Mg-Si alloy with silicon excess

cited By 0International audienceThe over-ageing of an Al-Mg-Si alloy with Silicon excess was investigated using global thermoelectric power (TEP) and hardness measurements combined with local techniques (Transmission Electron Microscopy (TEM) and Atom Probe Tomography (APT)), in order to highlight how the peak-aged microstructure obtained by a T6 treatment evolves in use conditions at temperatures between 100 °C and 350 °C, leading to a progressive loss of mechanical strength. First, TEP was found to be relevant to study the over-ageing kinetics of the alloy due to its perfect correlation with hardness and its sensitivity to the microstructural changes occurring after peak hardness. Then, APT and TEM observations clearly showed that over-ageing is due to the progressive replacement of the β″ phase by a succession of different types of semi-coherent phases (firstly, of Type B and then of Type A and Type C) and by an extensive precipitation of pure silicon particles. At the highest temperature (T = 350 °C), it was highlighted that the influence of manganese cannot be neglected. From these studies, an experimental Isothermal Transformation Curve could be proposed in the investigated temperature range. Lastly, the decrease in mechanical strength taking place during isothermal and non-isothermal ageing from a T6 state was experimentally characterised and successfully analysed using the JMAK formalism. © 201