93 research outputs found
Réseau social et rétablissement: de l'influence du réseau social des personnes toxicodépendantes sur leur processus de rétablissement : travail de bachelor effectué dans le cadre de la formation à la Haute école de travail social de GenÚve
Les problĂšmes dâaddiction sont souvent abordĂ©s sous lâangle des politiques de santĂ© publique. Dans notre travail, nous avons traitĂ© cette problĂ©matique en lien avec le rĂ©seau social des personnes toxicodĂ©pendantes ayant travaillĂ© leur processus de rĂ©tablissement Ă Argos, association dâaide aux personnes toxicodĂ©pendantes. Notre hypothĂšse est que possĂ©der un rĂ©seau social non-consommateur permettrait un ancrage dans une vie abstinente durable et stable. Pour traiter ce sujet, nous avons posĂ© un cadre thĂ©orique qui touche le contexte sociopolitique dans lequel notre travail sâinscrit. Nous avons ensuite rĂ©flĂ©chi sur la conceptualisation de la toxicodĂ©pendance, des processus de socialisation, de la dynamique des rĂ©seaux sociaux et des mĂ©canismes dâappartenance au groupe. Notre analyse se divise en trois axes. Dans la premiĂšre partie, nous nous sommes intĂ©ressĂ©es Ă ce qui sâest jouĂ© au moment de lâĂ©mergence de la toxicomanie, en prenant lâangle de la rupture de la socialisation ordinaire et de la marginalisation qui en a dĂ©coulĂ©. Dans la seconde partie, nous avons envisagĂ© le groupe dâappartenance comme maintien des conduites addictives. Nous terminons cette partie empirique par la sortie du contexte de toxicomanie, que nous avons choisi de traiter en intĂ©grant les principes de rĂ©silience. Notre constatation est que cette problĂ©matique est Ă comprendre dans sa globalitĂ© et que le processus de rĂ©tablissement dĂ©pend de facteurs sociĂ©taux, sociaux, individuels et relationnels
Influence of Chemistry on the Tensile Yield Strength of Nickel-Based Single Crystal Superalloys
Abstract. The tensile yield strength of AM1 and MC-NG single crystal superalloys with a γ' precipitate size close to 300 nm were compared within the 20-1050°C temperature range. The room temperature yield strength of the fourth generation MC-NG superalloy is about 200 MPa less than that of the AM1 first generation one. Inversely, at higher temperatures (T > 800°C), the tensile strength of MC-NG is higher than that of AM1. These results are discussed by taking into account the elementary deformation mechanisms and the respective strengths of the γ and γ' phases. Experiments on a modified MC-NG alloy show that reinforcing the γ' phase by increasing the contents of Ti and Ta is an efficient way to recover a higher tensile strength at low temperatures. Rhenium addition and increase of the γ' solvus temperature are suggested to be beneficial for the high temperature tensile strength. Data published on various other single crystals are in agreement with these hypotheses
Corrélation entre la forme d'inclusions intergranulaires et l'énergie de joints de grains dans un alliage Cu-1Pb
Le plomb ajoutĂ© dans le cuivre et ses alliages est prĂ©sent aux joints de grains Ă l'Ă©quilibre capillaire sous la forme de lentilles dont la gĂ©omĂ©trie est gouvernĂ©e par leur angle diĂšdre. Une mĂ©thode de mesure de l'angle diĂšdre permettant d'accĂ©der Ă une valeur prĂ©cise pour chaque inclusion a Ă©tĂ© dĂ©veloppĂ©e et appliquĂ©e aux inclusions individuelles dans un alliage Cu-1Pb. Les rĂ©sultats obtenus sur une sĂ©rie d'inclusions montrent une grande dispersion Ă l'Ă©chelle d'un Ă©chantillon. Cette observation est interprĂ©tĂ©e comme une consĂ©quence du fait que, pour une tempĂ©rature d'Ă©quilibration spĂ©cifique, l'angle diĂšdre sur un joint de grains dĂ©fini dĂ©pend de l'Ă©nergie de celui-ci. La dispersion constatĂ©e sur les valeurs d'angle diĂšdre obtenues sur un mĂȘme Ă©chantillon peut dĂšs lors ĂȘtre reliĂ©e Ă la dispersion de l'Ă©nergie des joints de grains au sein d'un polycristal, laquelle peut Ă son tour ĂȘtre reliĂ©e Ă la dĂ©sorientation relative entre les grains, puisque cette derniĂšre est mesurable par analyse EBSD. Le prĂ©sent article prĂ©sente des premiers rĂ©sultats de cette approche
The effect of density and feature size on mechanical properties of isostructural metaffic foams produced by additive manufacturing
Simple models describing the relationship between basic mechanical properties and the relative density of various types of porous metals (such as foams, sponges and lattice structures) are well established. Carefully evaluating these relationships experimentally is challenging, however, because of the stochastic structure of foams and the fact that it is difficult to systematically isolate density changes from variations in other factors, such as pore size and pore distribution. Here a new method for producing systematic sets of stochastic foams is employed based on electron beam melting (EBM) additive manufacturing (AM). To create idealised structures, structural blueprints were reverse-engineered by inverting X-ray computed tomographs of a randomly packed bed of glass beads. This three-dimensional structure was then modified by computer to create five foams of different relative density Ïr, but otherwise consistent structure. Yield strength and Youngâs modulus have been evaluated in compression tests and compared to existing models for foams. A power of 3 rather than a squared dependence of stiffness on relative density is found, which agrees with a recent model derived for replicated foams. A similar power of 3 relation was found for yield strength. Further analysis of the strength of nominally fully dense rods of different diameters built by EBM AM suggest that surface defects mean that the minimum size of features that can be created by EBM with similar strengths to machined samples is âŒ1 mm
Influence of Grain Boundary Character on Creep Void Formation in Alloy 617
Alloy 617, a high temperature creep-resistant, nickel-based alloy, is being considered for the primary heat exchanger for the Next Generation Nuclear Plant (NGNP) which will operate at temperatures exceeding 760oC. Orientation imaging microscopy (OIM) is used to characterize the grain boundaries in the vicinity of creep voids that develop during high temperature creep tests (800-1000oC at creep stresses ranging from 20-85 MPa) terminated at creep strains ranging from 5-40%. Observations using optical microscopy indicate creep rate does not significantly influence the creep void fraction at a given creep strain. Preliminary analysis of the OIM data indicates voids tend to form on grain boundaries parallel, perpendicular or 45o to the tensile axis, while few voids are found at intermediate inclinations to the tensile axis. Random grain boundaries intersect most voids while CSL-related grain boundaries did not appear to be consistently associated with void development
Cast aluminium single crystals cross the threshold from bulk to size-dependent stochastic plasticity
Metals are known to exhibit mechanical behaviour at the nanoscale different to bulk samples. This transition typically initiates at the micrometre scale, yet existing techniques to produce micrometre-sized samples often introduce artefacts that can influence deformation mechanisms. Here, we demonstrate the casting of micrometre-scale aluminium single-crystal wires by infiltration of a salt mould. Samples have millimetre lengths, smooth surfaces, a range of crystallographic orientations, and a diameter D as small as 6âÎŒm. The wires deform in bursts, at a stress that increases with decreasing D. Bursts greater than 200ânm account for roughly 50% of wire deformation and have exponentially distributed intensities. Dislocation dynamics simulations show that single-arm sources that produce large displacement bursts halted by stochastic cross-slip and lock formation explain microcast wire behaviour. This microcasting technique may be extended to several other metals or alloys and offers the possibility of exploring mechanical behaviour spanning the micrometre scale
Open Celled Porous Titanium
Among the porous metals, those made of titanium attract particular attention due to the interesting properties of this element. This review examines the state of research understanding and technological development of these materials, in terms of processing capability, resultant structure and properties, and the most advanced applications under development. The impact of the rise of additive manufacturing techniques on these materials is discussed, along with the likely future directions required for these materials to find practical applications on a large scale
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