Search results for "process"
showing 10 items of 22310 documents
Active lighting applied to three-dimensional reconstruction of specular metallic surfaces by polarization imaging
2006
International audience; In the field of industrial vision, the three-dimensional inspection of highly reflective metallic objects is still a delicate task. We deal with a new automated three-dimensional inspection system based on polarization analysis. We first present an extension of the shape-from-polarization method for dielectric surfaces to metallic surfaces. Then, we describe what we believe to be a new way of solving the ambiguity concerning the normal orientation with an active lighting system. Finally, applications to shape-defect detection are discussed, and the efficiency of the system to discriminate defects on specular metallic objects made by stamping and polishing is presente…
Giovani e partecipazione al tempo dei social media. Verso la media education e oltre
2022
Il presente capitolo ricostruisce, attraverso una disamina della letteratura scientifica di riferimento, il tema del rapporto tra giovani e partecipazione in rete. Il primo paragrafo ripercorre brevemente le principali tesi con cui si è cercato di descrivere e spiegare in che modo i media digitali e la rete sono una risorsa cruciale nel processo di socializzazione e costruzione dell’identità di adolescenti e giovani. Successivamente verranno definiti e problematizzati i concetti di partecipazione e creatività con cui spesso si descrivono le pratiche di uso della rete da parte dei giovani. A partire da questa problematizzazione e da alcune note critiche sulla “cultura connettiva” nella platf…
La territorialisation des politiques scolaires : l'exemple des collèges du bassin de Gap
2006
ACL; International audience; Le bassin de Gap connaît un accroissement démographique en milieu périurbain, ce qui nécessite l'analyse de la carte scolaire afin de créer de nouveaux collèges. Ce bassin de population, marqué par des contraintes fortes, est un véritable espace vécu dans le sens où il est structuré par des aires de recrutement résultant des pratiques spatiales des élèves et de leurs familles. Une étude approfondie des structures et des dynamiques spatiales de ce bassin permet de tirer quelques leçons quant au fonctionnement d'un territoire scolaire.
Interest Representation Preconditions in Illiberal Poland and Hungary
2022
Poland and Hungary have been widely recognised as countries affected by illiberalism. This has undoubtedly created a challenging environment for interest groups; groups which are a touchstone for the quality of democratic processes. In this article, we aim to understand how preconditions for interest representation have changed due to illiberal drift through the eyes of interest groups operating in these two selected post-communist countries. In order to examine their perception of opportunity structures, interaction infrastructure as well as the level of political coordination under the new circumstances, we rely on quantitative research in the form of a survey carried out among interest g…
La sociedad multicultural. Democracia y derechos
1997
En este artículo, el autor parte de un hecho sustancial: las sociedades multiculturales constituyen un fenómeno característico de nuestro tiempo. Es decir, en las sociedades actuales conviven códigos e identidades culturales diversos como consecuencia de diferencias étnicas, lingüísticas, religiosas o nacionales. En Europa, este fenómeno responde a la fragmentación de sociedades altamente homogéneas, a la crisis de consensos internos y del modelo del Estado social, a los flujos migratorios, etcétera. Ciertamente, la complejidad de las sociedades multiculturales plantea desafíos a la democracia: ¿cómo conciliar la unidad política con la diversidad social? El autor analiza el debate generado …
Metallocenes and post-metallocenes immobilized on ionic liquid-modified silica as catalysts for polymerization of ethylene
2014
Abstract The supported ionic liquid (SIL) strategy was used for the first time to metallocene and post-metallocene heterogeneous catalysts for olefin polymerization. The metal complexes: Cp2TiCl2, Cp2ZrCl2, FI–Ti, and Sal–Ti were immobilized in the 1-(3-triethoxysilyl)propyl-3-methylimidazolium alkylchloroaluminate ionic liquid, anchored on the surface of the mesoporous amorphous silica. The SIL systems were characterized by FTIR, 29Si NMR, N2 adsorption, EA, AAS, TG, and SEM techniques. The developed supported catalytic systems were found to be active in the ethylene polymerization and produce the polyethylene of various properties.
On the effectiveness of different additives and concentrations on the re-building of the molecular structure of degraded polyethylene
2006
Mechanical recycling is an easy and economic way to re-use plastic waste as secondary materials, but, in general, their properties are worse with respect to the reclaimed materials and the virgin polymer. The aim of this work was to study the effect of concentration and reaction kinetics of two additives, an ethylene-co-glycidyl methacrylate (Lotader) and a hydroxylamine derivative (CGX), in the re-building of a degraded polyethylene. CGX is a nitroxyl radical generator able to form branching in polyolefins while the epoxy groups of Lotader can react with the functional groups present in the recycled polyethylene. The results indicate that the CGX has a higher reaction rate than Lotader, pr…
On the Preparation and the Characterization of Polyethylene/Polyamide Blends by Melt Processing in the Presence of an Ethylene(co)acrylic Acid Copoly…
2006
Samples of HDPE and PA6 have been meltprocessed in the presence of two new phosphazene compounds, CP-2EPOX and CP-2OXA together with an ethylene/ acrylic acid copolymer. The blends have been prepared in an industrial twin-screw extruder by using PA6 and PE in weight ratios of 25/75 and 75/25. When used, 5 phr of EAA and 0.2 phr of CP have been added. The materials have been completely characterized from a rheological, morphological, and mechanical point of view. The results indicate that the additives used caused an increase in the rupture tensile properties, of the impact strength and viscosity especially in the PE-rich blend in the presence of CP-2EPOX. This result can be attributed both …
Enhanced chain dynamics in loop-sorting-systems by means of layout optimization and a kinematic model of the polygon action
2012
Published version of an article in the journal: Structural and Multidisciplinary Optimization. Also available from the publisher at: http://dx.doi.org/10.1007/s00158-011-0743-7 Poor dynamics owing to polygon action is a known concern in mechanical applications of closed articulated chains. In this paper a kinematic model of the polygon action in large chains of loop-sorting-systems is proposed. Through optimization techniques the chain dynamics is improved by minimizing the polygon action using a parametric model of the track layout as design variables. Three formulations of the kinematic polygon action are tested on an average sized planer tracks layout to find a superior model. Verificati…