M5_Framatome cladding high temperature oxidation behavior during simulated LOCA transients

International audienceDemonstrating the satisfying cladding oxidation behavior in LOCA conditions and predicting accurately breakaway occurrence is of importance for the cladding producer and its customers. FRAMATOME developed a dedicated facility at his PAIMBOEUF plant in order to perform one- and two-sided oxidation tests in steam, with a tight monitoring (temperature, steam flow). M5Framatome claddings were oxidized at temperatures from 800 to 1100°C for at least 5000 s. Parabolic kinetics, protective oxides and a lack of significant hydrogen pick-up were observed. These tests confirmed the M5Framatome excellent behavior and the absence of breakaway in these conditions. Metallography and SEM observations allowed us to quantify the layers’ thicknesses of the oxide the oxygen-stabilized alpha phases. The metal/oxide interface roughness as well as the oxide porosity were also estimated by image analysis, and are shown to depend on the oxidation temperature. In parallel, Finite Element Modeling of the oxidation and the addition elements’ diffusion was developed. Diffusion equations take into account the evolution of the chemical potentials of the elements, computed thanks to the THERMOCALC software and the FRAMATOME ARTABAZ thermodynamic database. Calculated diffusion profiles are compared to experimental data and discussed

The Wade Formula and the oil price fluctuation: An Optimal Control Theory approach

By considering the Wade Formula, we propose a model to study the evolution of the oil price per barrel. Our model shows that the policy of diversification of the energy is to be supported. This model is proposed to see how it is possible to control parameters so that the oil price should decrease

Exploring robust, intuitive and emergent physical human-robot interaction with the humanoid Acroban

International audienceWe present how a humanoid robot, called Acroban, allows whole-body robust, natural and intuitive physical interac- tion with both adults and children. These physical human-robot interaction are made possible through the combination of several properties of Acroban: 1) it is whole-body compliant thanks to variable impedance control and also thanks to the use of elastics and springs; 2) it has a bio-inspired vertebral column allowing more flexibility in postural and equilibrium control; 3) it is light- weight; 4) it has simple low-level controllers that leverage the first three properties. Moreover, the capabilities for physical human- robot interaction that we show are not using a model of the human, and in this sense are "model free": 1) the capability of the robot to keep its equilibrium while being manipulated or pushed by humans is a result of the intrinsic capability of the whole body to absorb unpredicted external perturbations; 2) the capability of leading Acroban by the hand is an emergent human-robot interface made possible by the self-organizing properties of the body and its low-level controllers and was observed a posteriori only after the robot was conceived and without any initial plan to make this possible. Finally, an originality of Acroban is that is is made with relatively low-cost components which lack of precision is counterbalanced with the robustness due to global geometry and compliance

New simplified analytical method for the Prediction of global stability of steel and composite sway frames

peer reviewedEurocode 4 is the European design code for composite construction; in its so-called EN 1994-1-1 version, the design of “non-sway buildings” is mainly covered. As a result, EC4 focuses on the check of structural elements like beams, columns, slabs and joints. However, in the last years, the construction of taller buildings and larger industrial halls without wind bracing systems tends to make global instability a relevant failure mode, which is not well covered by Eurocode 4. Recently, intensive experimental, numerical and theoretical investigations have been carried out at Liège University. The latter aimed at improving the knowledge in the field of sway composite building frames and at developing appropriate design rules. The rotational behavior of the beam-to-column composite joints is one of the key aspects of the problem to which a special attention has been paid. This paper reflects investigations carried out at Liege University on this topic. In particular, an innovative simplified analytical method to predict the ultimate loading factor and the associated collapse mode of both steel and composite frames subjected to static loadings is presented

Acroban the Humanoid: Playful and Compliant Physical Child-Robot Interaction

International audienceCompliance and semi-passive dynamics in the framework of humanoid robot locomotion Advantages of a multi-articulated vertebral column in dynamic semi-passive motor primitives Natural playful child-robot physical interaction The illusion of life: dynamic movement, touch and the Luxo Jr. effec

Maturational constraints for motor learning in high-dimensions: the case of biped walking

International audienceThis paper outlines a new developmental approach to motor learning in very high-dimensions, applied to learning biped locomotion in humanoid robots. This approach relies on the formal modeling and coupling of several advanced mechanisms inspired from human development for actively controlling the growth of complexity and harnessing the curse of dimensionality: 1) Maturational constraints for the progressive release of new degrees of freedoms and progressive increase their explorable ranges; 2) Motor synergies; 3) Morphological computation; 4) Social Guidance. An experimental setup involving a simulated version of the Acroban Humanoid robot is presented

Modeling maturational constraints for learning biped humanoid locomotion

International audienceThis paper outlines a new developmental approach to motor learning in very high-dimensions, applied to learning biped locomotion in humanoid robots. This approach relies on the formal modeling and coupling of several advanced mechanisms for actively controlling the growth of complexity and harnessing the curse of dimensionality: 1) Adaptive, multi-objective and staged fitness functions; 2) Maturational constraints for the progressive release of new degrees of freedoms; 3) Artificial curiosity; 4) Motor synergies; 5) Morphological computation. An experimental setup involving both the Acroban humanoid robot and a simulated version of the robot is presented

Bio-inspired vertebral column, compliance and semi-passive dynamics in a lightweight robot

International audienceThis paper presents the humanoid robot Acroban. We study two main issues: 1) Compliance and semi-passive dynamics for locomotion of humanoid robots regarding robustness against unknown external perturbations; 2) The advantages of a bio-inspired multi-articulated vertebral column. We combine mechatronic compliance with structural compliance due to the use of flexible materials. And we explore how these capabilities allow to enforce morphological computation in the design of robust dynamic locomotion. We also investigate the use of compliance to design semi-passive motor primitives using the torso and the arms as a system of accumulation/release of potential/kinetic energy

Increase of malaria attacks among children presenting concomitant infection by Schistosoma mansoni in Senegal

Helminthic infections concomitant with malaria are common in inter-tropical areas. A recent study showed that mice co-infected with Schistosoma mansoni and Plasmodium chabaudi develop higher P. chabaudi parasitaemia and had a higher mortality rate. This important observation deserved to be further investigated among human populations. Malaria attacks were recorded in 512 children aged 6–15 years living in Richard Toll (Northern Senegal) among whom 336 were infected by S. mansoni, and 175 were not. The incidence rate of malaria attacks was significantly higher among S. mansoni-infected individuals, particularly those carrying the highest worm loads, as compared to uninfected subjects (26.6% versus 16,4 %). In contrast, the rate of malaria attacks was lower, without reaching significance, in medium grade S. mansoni infections. Thus, infection by S. mansoni affects susceptibility to malaria, but this can vary according to the intensity of parasite load. The immunological mechanisms underlying this dual effect need to be further explored