Development of a Portable Device for Thermoelectrical Power Measurement—Application to the Inspection of Duplex Stainless Steel Components

Some cast components of the primary loop of French Pressurized Water Reactors are made of cast duplex stainless steels. The mechanical characteristics of these components, working in the temperature range from 285°C to 325°C, may be altered by thermal aging : the hardness of the materials increases whereas its toughness decreases with aging time and temperature. The metallurgical explanation of this phenomena is the unmixing of the ferritic Fe-Cr-Ni solid solution by spinodal decomposition and the precipitation of intermetallic G-phase particles rich in nickel and silicium [1]

Propositions d'architecture de controleur ouvert pour la robotique

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Solution Structures of a Cyanobacterial Metallochaperone: INSIGHT INTO AN ATYPICAL COPPER-BINDING MOTIF *

The Atx1 copper metallochaperone from Synechocystis PCC 6803, ScAtx1, interacts with two P(1)-type copper ATPases to supply copper proteins within intracellular compartments, avoiding ATPases for other metals en route. Here we report NMR-derived solution structures for ScAtx1. The monomeric apo form has a betaalphabetabetaalpha fold with backbone motions largely restricted to loop 1 containing Cys-12 and Cys-15. The tumbling rate of Cu(I)ScAtx1 (0.1-0.8 mm) implies dimers. Experimental restraints are satisfied by symmetrical dimers with Cys-12 or His-61, but not Cys-15, invading the copper site of the opposing subunit. A full sequence of copper ligands from the cell surface to thylakoid compartments is proposed, considering in vitro homodimer liganding to mimic in vivo liganding in ScAtx1-ATPase heterodimers. A monomeric high resolution structure for Cu(I)ScAtx1, with Cys-12, Cys-15, and His-61 as ligands, is calculated without violations despite the rotational correlation time. (2)J(NH) couplings in the imidazole ring of His-61 establish coordination of N(epsilon2) to copper. His-61 is analogous to Lys-65 in eukaryotic metallochaperones, stabilizing Cu(I)S(2) complexes but by binding Cu(I) rather than compensating charge. Cys-Cys-His ligand sets are an emergent theme in some copper metallochaperones, although not in related Atx1, CopZ, or Hah1. Surface charge (Glu-13) close to the metal-binding site of ScAtx1 is likely to support interaction with complementary surfaces of copper-transporting ATPases (PacS-Arg-11 and CtaA-Lys-14) but to discourage interaction with zinc ATPase ZiaA and so inhibit aberrant formation of copper-ZiaA complexes

Safe Navigation for Indoor Mobile Robots - PartII: Exploration, Self Localization and Map Building

International audienceThis paper is the second part of the author's contribution on the topic of Safe Navigation for Indoor Mobile Robots. It presents a new solution to the exploration, self localization and map building problem taking advantage of the sensor-based navigation framework presented in the paper: Safe Navigation for Indoor Mobile Robots - Part I: A Sensor-based Navigation Framework. The model of the indoor environment is structured as an hybrid representation, both topological and geometrical, which is incrementally built during the exploration task. The topological aspect of the model captures the connectivity and accessibility of the different places in the environment, and the geometrical model holds up an accurate robot localization and map building method. To overpass the problem of drift inherited to the odometry when the robot navigates in large scale environments, a new dead-reckoning method is proposed combining laser readings and feedback control inputs. Embedding the self-localization and map building problem in a sensor-based navigation framework improves both the quality and the robustness of the representation built during the exploration phase and authorizes a further use to achieve safe navigation tasks successfully. Experiments are shown which confirm the interests of the proposed methodology

Safe Navigation for Indoor Mobile Robots. Part I: A Sensor-based Navigation Framework

International audienceThis paper presents a first part, Part-I of two, of a complete exploration and navigation methodology that enables a robot to safely navigate in an unknown environment. Reactive sensor-based navigation tasks and control laws are derived from the interaction between the robot and its workspace. The perception is performed by a 2-D laser nge finder mounted on the robot. Reactive navigation tasks are defined based on the task function framework in a such a way that the robot can explore an unknown indoor environment without any reference rajectory computation. Obstacle avoidance is ensured as a straight property implicit to the definition of the navigation tasks. The stability and obustness of the derived control laws with respect to the model errors are analyzed. The experimental results validate the proposed methodology