SURFACE ENGINEERING FOR PARTS MADE BY ADDITIVE MANUFACTURING

peer reviewedthe surface preparation of metal parts made by additive manufacturing (AM). AM is a technology of choice for manufacturing of parts with complex shapes (heat exchangers, RF supports, optical parts…) and integrated functions such as conformal cooling channels, clips, hinges, etc. This opens the door for lightweight parts which are of prime importance for space applications. The potential of the AM technologies is however impeded by the quite rough surface finish that is observed on the as-manufactured parts. It is known that such a finish is likely to impact the performance of the parts. Several post-treatment techniques can be applied to improve the surface condition of the AM parts. However, so far, the influence of the successive post-processing steps on the final properties is not well established. Therefore, a better understanding of the impact of surface characteristics on the material behaviour is needed to expand the use of AM for high performance parts. The objective of this study, supported by ESA, is to propose and evaluate various surface finishing techniques for parts made by the AM technologies, in order to check their compatibility, evaluate their properties and derive guidelines for future applications. CRM is the prime proposer of this study and is in charge of the surface treatment and characterisations. Sirris additive manufacturing facilities are used to produce the parts. Thales Alenia Space and Walopt are included into the industrial team to provide concrete application cases. The study focuses on metals. Two metals under study are presented here: AlSi10Mg and Ti6Al4V. This paper is devoted to the early results of the first steps of surface preparation, namely material removal from the surface of the produced parts in order to improve their surface properties. As a first phase, tribo-finishing (TF) is tested on prototype parts to check its capabilities. Surface and volume parameters are analyzed, namely achieved roughness, material removal rate, location of removed material. The limitations in terms of geometry and applicability are discussed as well. These first observations should serve as guidelines for further application of AM for the design of parts used in space industry

Les non-réponses sont-elles des reponses ?Étude des valeurs manquantes dans un 360˚ feed-back

International audienceL’étude présentée cherche à comprendre le phénomène des non-réponses à un questionnaire d’appréciation conçu et mis en place ponctuellement dans les organisations dans une optique de soutien au développement des compétences des salariés et à leur apprentissage organisationnel. Une analyse quantitative exploratoire a été menée. Elle a consisté à exploiter statistiquement les données recueillies dans le cadre d’un dispositif de type 360˚ Feed-Back auprès de 1 873 salariés s’autoévaluant ou évalués par leurs collègues, leurs responsables ou leurs managés, représentant 17 176 salariés de leur entourage professionnel. L’étude s’est focalisée sur la population des répondants ayant laissé au moins une valeur manquante dans le questionnaire. Ils représentaient une base de 11 202 répondants, soit 58,81 % des salariés concernés, répartis dans 183 entreprises différentes. Les résultats de l’analyse des données nous ont conduits d’une part à confirmer que ces non-réponses ne sont pas dues au hasard, et d’autre part à considérer qu’elles sont porteuses de sens et qu’elles peuvent être pour partie nécessaires au développement des compétences professionnelles et l’apprentissage organisationnel

Saisie de texte en mobilité avec des claviers logiciels : optimisation par l'usage d'indices visuels

National audienc

Characterization of Lattices Induced by (extended) Chip Firing Games

The Chip Firing Game (CFG) is a discrete dynamical model used in physics, computer science and economics. It is known that the set of configurations reachable from an initial configuration (this set is called the configuration space) can be ordered as a lattice. We first present a structural result about this model, which allows us to introduce some useful tools for describing those lattices. Then we establish that the class of lattices that are the configuration space of a CFG is strictly between the class of distributive lattices and the class of upper locally distributive (or ULD) lattices. Finally we propose an extension of the model, the coloured Chip Firing Game, which generates exactly the class of ULD lattices

Characterization of Lattices Induced by (extended) Chip Firing Games

The Chip Firing Game (CFG) is a discrete dynamical model used in physics, computer science and economics. It is known that the set of configurationsreachable from an initial configuration (this set is called the \textitconfiguration space) can be ordered as a lattice. We first present a structural result about this model, which allows us to introduce some useful tools for describing those lattices. Then we establish that the class of lattices that are the configuration space of a CFG is strictly between the class of distributive lattices and the class of upper locally distributive (or ULD) lattices. Finally we propose an extension of the model, the \textitcoloured Chip Firing Game, which generates exactly the class of ULD lattices

Mobile Text Input with Soft Keyboards: Optimization by Means of Visual Clues

International audienceSoft keyboards are one of the most popular methods to input text for mobile pen-based computing. They allow text input to be performed through an onscreen graphical representation of a standard desk keyboard. Besides standard QWERTY keyboard layout, some researchers have proposed optimized alternative key organizations to improve user performances with soft keyboards. In this paper we propose and evaluate a solution using visual clues to facilitate the acceptance of these optimized layouts by novices

Characterization of Lattices Induced by (extended) Chip Firing Games

The Chip Firing Game (CFG) is a discrete dynamical model used in physics, computer science and economics. It is known that the set of configurationsreachable from an initial configuration (this set is called the \textitconfiguration space) can be ordered as a lattice. We first present a structural result about this model, which allows us to introduce some useful tools for describing those lattices. Then we establish that the class of lattices that are the configuration space of a CFG is strictly between the class of distributive lattices and the class of upper locally distributive (or ULD) lattices. Finally we propose an extension of the model, the \textitcoloured Chip Firing Game, which generates exactly the class of ULD lattices