554 research outputs found
Initiation and growth of short cracks during cycling in an aged superduplex stainless steel
No full textThe kinetics of short crack growth during cycling has been studied in a superduplex stainless steel in aged condition. After few cycles, slip lines appear distributed in both phases but the preferred phase for microcrack nucleation is the ferrite. Contrary to the exponential behavior observed in the as-received material, the growth rate of microcracks in aged condition follows a rather linear law. Internal dislocation structures were studied in the near surface region; microbands that sometimes extend over several grains were found at approximately 45º of the tensile axis on ferrite grains. The origin of the microbands has been analyzed and correlated with the microcracks.Fil: Balbi, Marcela Ángela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Física de Rosario (i); ArgentinaFil: Hereñu, Silvina Andrea Noemi. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Física de Rosario (i); ArgentinaFil: Proriol Serre, I.. Université de Lille; FranciaFil: Vogt, J. B.. Université de Lille; FranciaFil: Armas, A. F.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Física de Rosario (i); ArgentinaFil: Alvarez Armas, I.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Física de Rosario (i); Argentin
Selection of variables for neural network analysis: comparisons of several methods with high energy physics data
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Classification of hadronic events in e+e- collisions with neural networks: applications to tag the quark and the number of jets
No full textDefinition of new 3D invariants: applications to pattern recognition problems with neural networks
No full textMLP-RBF: a cooperative multi-modular neural network application in high-energy physics
No full textAbstract : The aims of this work is, firstly to propose a new assimilation of the visibility relationship of VBOOL in the UML (Unified Modeling Language) standard language for modeling and specifying objectoriented systems. Secondly, to complete UML by an oriented viewpoint method to get a complete software engineering process. U_VBOOM method represent an adaptation of VBOOM (View Based Object-Oriented Method) integrating the UML notation. The new U_VBOOM method keeps main VBOOM concepts and integrates to its development process strong points of UML such as use cases and a new stereotype that allows with the aggegation relationship to implemente the visibility relationship. This new approach encourages the multi-targets code generation and improve the process of development proposed by the VBOOM method
Compréhension de la fragilisation de l’acier T91 par l’eutectique Plomb-Bismuth liquide : analyses par ToF-SIMS pour évaluer l’absorption du Plomb et du Bismuth.
No full textFor the development of ADS and Generation IV reactors cooled by liquid lead-bismuth eutectic (LBE) or liquid lead, the sensitivity of structural materials to liquid metal embrittlement (LME) or to liquid metal assisted damage has been studied since several years. For one of them, the T91 martensitic steel, a very selective set of parameters including test temperature, strain rate, oxygen content in LBE, surface roughness, microstructure state of the steel promotes brittle fracture in LBE or an accelerating damage instead of ductile fracture in neutral environment (argon or air) under monotonic and cyclic loading [1-4]. The mechanisms that explain this embrittlement are generally based on the adsorption of the liquid metal atoms on the surface of the steel, which results in the local reduction of the shear stress and the reduction of the cohesion. Furthermore, LBE is not a pure metal but an alloy. Thus, it is not easy to estimate which between lead and bismuth contribute the most to LME. Moreover, the literature does not report at the moment any evidence of the penetration of Pb or Bi atoms in the iron networks even after long term pre-immersion in LBE. Thus, we studied if atoms of LBE can penetrate the lattice of T91 steel, and even segregate, during immersion under plastic deformation. Then, if so, it aims at determining if lead and bismuth produces the same degree of LME.Cyclic loading in LBE was applied on a notched flat specimen to obtain large value of cumulated plastic deformation at notch root. After test, ToF-SIMS (The time of flight secondary ion mass spectroscopy) analyses were performed to study the presence of the bismuth and lead in depth of the steel, under the surface. It is shown that both Pb and Bi can penetrate the steel network only in plastically deformed material. No microstructural interface (lath boundaries, grain boundaries ….) was found to be preferential site for trapping Pb and Bi but clustering with molybdenum has been identified. Pb seems to be easier adsorbed than Bi because of, we suppose, its higher affinity with oxygen. A mechanism based not only on adsorption but also on the absorption of Pb-Bi is proposed.References[1] G. Nicaise, A. Legris, J-B. Vogt, F. Foct, Embrittlement of the martensitic steel 91 tested in liquid lead, J. Nucl. Mater. 296 (2001) 256-264.[2] I. Serre, J.-B. Vogt, Heat treatment effect of T91 martensitic steel on liquid metal embrittlement, J. Nucl. Mater. 376 (2008), 330-335.[3] C. Ye, J-B. Vogt, I. Proriol Serre, Liquid metal embrittlement of the T91 steel in lead bismuth eutectic: The role of loading rate and of the oxygen content in the liquid metal, Mat. Sci. Eng. A 608 (2014) 242-248.[4] A. Verleene, J.-B. Vogt, I. Serre, A. Legris, Low cycle fatigue behaviour of T91 martensitic steel at 300 °C in air and in liquid lead bismuth eutectic, Int. J. Fatigue 28 (2006) 843-851.Dans le cadre du développement des ADS et des réacteurs de génération IV refroidis par l’eutectique plomb-bismuth (Pb-Bi) liquide, il a été étudié, si la présence du Pb-Bi induit une fragilisation par les métaux liquides (FML) ou une accélération de l’endommagement par métal liquide de l’acier martensitique T91. Des essais ont été menés à l’air et en métal liquide, suivis d’analyses approfondies des faciès de rupture, des chemins de fissuration, des surfaces et sous-surfaces. Il a été mis en évidence des conditions expérimentales et microstructurales menant à la FML de l’acier par Pb-Bi liquide. Un endommagement accéléré par métal liquide sous sollicitation cyclique est aussi observé. Les mécanismes expliquant ces phénomènes sont généralement basés sur l’adsorption des atomes de métal liquide à la surface de l’acier ce qui entraîne la réduction locale de la contrainte de cisaillement et la réduction de la cohésion.Cependant, à partir d’analyses ToF-SIMS de la surface et sous surface de l’acier déformé en présence de Pb-Bi, il est observé que Pb et Bi peuvent pénétrer au niveau de la couche d’oxyde et dans l’acier, ceci sous déformation plastique en présence de métal liquide. Les interfaces microstructurales de l’acier n’apparaissent pas comme des sites d’absorption privilégiés, cependant qu’une affinité de Mo et Pb-Bi est notée. Pb semble être plus facilement absorbé que Bi. Un mécanisme basé pas seulement sur l’adsorption mais aussi sur l’absorption de Pb-Bi est proposé
Selection of variables for neural network analysis Comparisons of several methods with high energy physics data
No full textDefinition of Invariants in 3 - D Application: Study of the number of jets in e+ e- events
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