Ductility is one of the main requirements of a reliable building material; the traditional LOP and MOR criteria do not reveal this quality. Other criteria based on deflection, energy or bond-slip relationships are presented. They are applied to four very different series of composites: very brittle, very ductile, and intermediate. The results point out that only the criteria based on the flexural test up to splitting, at a constant deflection rate, can reveal the higher ductility of the metakaoline-OPC blended matrix associated with AR glass. From this test, the bond-slip relationship can be determined. This leads to the definition of a comparative parameter which describes the mechanical interfacial compatibility of the matrix versus the fibers.
Résumé -Formalisation d'une approche structurée de modélisation d'un système industriel complexe par Réseaux de Petri : application aux systèmes de production pétroliers offshore Ultra Grands Fonds -Le travail présenté dans ce papier a pour objectif de proposer une méthodologie de modélisation permettant de combiner au sein d'un même modèle différents processus (sollicitation, défaillance, réparation, approvisionnement, etc.) concernant le système principal et son système de soutien. L'approche linéaire classiquement suivie dans la conduite de cet exercice met en évidence une difficulté de modélisation certaine due à la complexité et au nombre des aspects mis en jeu. Bien que l'approche apparaisse probante sur le plan des résultats, l'absence de structuration réduit la confiance susceptible d'être accordée aux modèles et implique en conséquence une attention accrue de la part du modélisateur. Pour résoudre ce problème, nous proposons une démarche structurée conduisant à la réali-sation de Réseaux de Petri capables de prendre en compte à la fois l'aspect physique des systèmes étudiés mais aussi des notions plus immatérielles liées aux stratégies mises en place. La finalité de cette approche est l'évaluation globale de la performance technico-économique d'un système dans sa phase d'exploitation pour l'identification des meilleures solutions sur le plan de l'architecture des systèmes mais aussi de l'organisation mise en place pour les faire fonctionner. La démarche de structuration de la modélisation par Réseaux de Petri est d'abord présentée avant d'être appliquée au cas d'un système industriel. (solicitation, failure, repair, supply, etc.) dealing with the main system but also with the logistic support system. The classical linear approach has to cope with a difficulty of modelling due to the complexity and the number of parameters of concern. Although the approach seems to be effective in term of results, the lack of structure reduces the confidence likely to be granted to the models and consequently implies an increased attention from the expert. In order to solve this problem, we propose a methodology leading to the building of Petri nets able to take into account both the physical aspects of the system and also more immaterial concepts related to actual strategies. The final goal of this approach is the global evaluation of the technico-economical performance of the system during its working period in order to identify the best solutions in term of system configuration and organization. The Petri nets modelling structured approach is first introduced before being applied to an industrial system. Abstract -Formalization of a Structured Approach for the Modelling of a Complex Industrial System by the Use of Petri Nets: Application to Ultra Deep Oil Production Systems -The work presented in this paper aims to propose a methodology of modelling allowing to combine into a single model different processes
Because of their high SO3 content (∼11%), sulfo-calcic fly ashes cannot be used as a cement admixture without pretreatment. The fly ashes contain mainly quicklime (CaO), anhydrite (CaSO4) and larnite (BC2S). At ambient temperatures and at normal consistency, their hydration leads to the formation of ettringite, slaked lime and gypsum. As a result, cracking and splitting of the hydrated product quickly occurs due to the crystallization of the ettringite.The ability of these fly ashes to produce Portlandite, Ca(OH)2, led the authors to investigate pozzolanic binders by the addition of artificial pozzolans — siliceous fly ashes, slag and clay minerals — which had been calcined at moderate temperatures.The sulfo-calcic fly ashes are ground, then slaked either in ambient or hydrothermal conditions (2 or 6 hours at 130°C). In the case of slaking under ambient conditions, ettringite is quickly produced with a definitive crystallographical structure. As a result, no volume change is observed after re-hydration of the material. By comparison, autoclave slaking does not lead to this phenomenon, and only slaked lime is produced.The rate of hydration is studied through the development of compressive strength and by analyses of the products by differential thermal analysis (DTA) and X-ray diffraction (XRD) at various hydration times. The best results are obtained using calcined laterite or blast furnace slag.
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