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Combining Positron Emission Particle Tracking and image analysis to interpret particle motion in froths / K.E. Cole in Minerals engineering, Vol. 23 N° 11-13 (Octobre 2010) 

Public ISBD [article]  in Minerals engineering > Vol. 23 N° 11-13 (Octobre 2010) . - pp. 1036–1044 Titre : Combining Positron Emission Particle Tracking and image analysis to interpret particle motion in froths Type de document : texte imprimé Auteurs : K.E. Cole, Auteur ; K.E. Waters, Auteur ; X. Fan, Auteur Année de publication : 2011 Article en page(s) : pp. 1036–1044 Note générale : Génie Minier Langues : Anglais (eng) Mots-clés : Flotation  froths  Flotation  bubbles  Froth  flotation Résumé : Previous research into particle motion in the froth zone has focussed on constructing detailed CFD models that describe the behaviour of particle classes with different properties; density, size and hydrophobicity. These models have been reasonably successful in predicting trends in the separation behaviour and how it can be manipulated. Models of separation sub-processes cannot readily be verified experimentally due to the opacity and fragility of froth systems. Positron Emission Particle Tracking (PEPT) can be applied to particles in froth flotation systems to observe the behaviour of individual particles in a mixed particle–liquid–gas system. However, measuring the particle position alone is not adequate as its behaviour is also affected by instantaneous froth events such as bubble coalescence. To link the observed particle behaviour to the froth behaviour requires multi-modal measurements. Video footage of a rising foam column was recorded simultaneously with PEPT data, so that the PEPT tracer trajectory could be explained in terms of foam structure and events. A time weighting function of cubic splines with kernel width 200 ms was used to remove the effects of signal noise. An ascending 70 μm hydrophilic tracer accelerated within vertical Plateau borders and decelerated in Plateau borders angled away from vertical. The tracer trajectory showed velocity peaks and troughs when it was contained in nodes in a rising foam. When the tracer descended within a foam showing convective roll, coalescence events and subsequent foam deformation directly influenced the tracer trajectory. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687510001457 [article] Combining Positron Emission Particle Tracking and image analysis to interpret particle motion in froths [texte imprimé] / K.E. Cole, Auteur ; K.E. Waters, Auteur ; X. Fan, Auteur . - 2011 . - pp. 1036–1044. Génie Minier Langues : Anglais (eng) in Minerals engineering > Vol. 23 N° 11-13 (Octobre 2010) . - pp. 1036–1044 Mots-clés : Flotation  froths  Flotation  bubbles  Froth  flotation Résumé : Previous research into particle motion in the froth zone has focussed on constructing detailed CFD models that describe the behaviour of particle classes with different properties; density, size and hydrophobicity. These models have been reasonably successful in predicting trends in the separation behaviour and how it can be manipulated. Models of separation sub-processes cannot readily be verified experimentally due to the opacity and fragility of froth systems. Positron Emission Particle Tracking (PEPT) can be applied to particles in froth flotation systems to observe the behaviour of individual particles in a mixed particle–liquid–gas system. However, measuring the particle position alone is not adequate as its behaviour is also affected by instantaneous froth events such as bubble coalescence. To link the observed particle behaviour to the froth behaviour requires multi-modal measurements. Video footage of a rising foam column was recorded simultaneously with PEPT data, so that the PEPT tracer trajectory could be explained in terms of foam structure and events. A time weighting function of cubic splines with kernel width 200 ms was used to remove the effects of signal noise. An ascending 70 μm hydrophilic tracer accelerated within vertical Plateau borders and decelerated in Plateau borders angled away from vertical. The tracer trajectory showed velocity peaks and troughs when it was contained in nodes in a rising foam. When the tracer descended within a foam showing convective roll, coalescence events and subsequent foam deformation directly influenced the tracer trajectory. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687510001457

Contact mechanisms of transfer layered surface during sliding wear of amorphous carbon film / X. Fan in Transactions of the ASME . Journal of tribology, Vol. 133 N° 4 (Octobre 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of tribology > Vol. 133 N° 4 (Octobre 2011) . - 10 p. Titre : Contact mechanisms of transfer layered surface during sliding wear of amorphous carbon film Type de document : texte imprimé Auteurs : X. Fan, Auteur ; D. F. Diao, Auteur Année de publication : 2012 Article en page(s) : 10 p. Note générale : Tribology Langues : Anglais (eng) Mots-clés : Amorphous  semiconductors  Carbon  Cyclotron  resonance  Finite  element  analysis  Scanning  electron  microscopy  Shear  strength  Silicon  compounds  Sliding  friction  Wear  X-ray  chemical  analysis Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The contact mechanisms of a transfer layered surface during sliding wear of a Si3N4 ball against the amorphous carbon film were investigated. In this study, amorphous carbon films were deposited by electron cyclotron resonance plasma sputtering technique. The dependence of friction coefficient and wear life of the films on transfer layer was tested with pin-on-disk tribometer. Wear tracks and the transfer layered surfaces at different friction coefficient stages were observed with scanning electron microscope and measured with energy dispersive spectrometer In order to clarify the contact mechanisms of a transfer layered surface, three contact models of initial high friction coefficient stage without transfer layer (state I), transfer layer forming stage with friction coefficient decreasing (state II), and transfer layered surface stable sliding stage with low friction coefficient (state III) were proposed, and the contact stresses (normal stress, shear stress, von Mises stress) of the three contact states were calculated by using finite element analysis. The results demonstrated that a transfer layer formed at the contact interface and gradually decreased the maximum contact stresses, which contributed to the long wear life of amorphous carbon films. DEWEY : 621.5 ISSN : 0742-4787 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JOTRE900013 [...] [article] Contact mechanisms of transfer layered surface during sliding wear of amorphous carbon film [texte imprimé] / X. Fan, Auteur ; D. F. Diao, Auteur . - 2012 . - 10 p. Tribology Langues : Anglais (eng) in Transactions of the ASME . Journal of tribology > Vol. 133 N° 4 (Octobre 2011) . - 10 p. Mots-clés : Amorphous  semiconductors  Carbon  Cyclotron  resonance  Finite  element  analysis  Scanning  electron  microscopy  Shear  strength  Silicon  compounds  Sliding  friction  Wear  X-ray  chemical  analysis Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The contact mechanisms of a transfer layered surface during sliding wear of a Si3N4 ball against the amorphous carbon film were investigated. In this study, amorphous carbon films were deposited by electron cyclotron resonance plasma sputtering technique. The dependence of friction coefficient and wear life of the films on transfer layer was tested with pin-on-disk tribometer. Wear tracks and the transfer layered surfaces at different friction coefficient stages were observed with scanning electron microscope and measured with energy dispersive spectrometer In order to clarify the contact mechanisms of a transfer layered surface, three contact models of initial high friction coefficient stage without transfer layer (state I), transfer layer forming stage with friction coefficient decreasing (state II), and transfer layered surface stable sliding stage with low friction coefficient (state III) were proposed, and the contact stresses (normal stress, shear stress, von Mises stress) of the three contact states were calculated by using finite element analysis. The results demonstrated that a transfer layer formed at the contact interface and gradually decreased the maximum contact stresses, which contributed to the long wear life of amorphous carbon films. DEWEY : 621.5 ISSN : 0742-4787 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JOTRE900013 [...]