126 research outputs found
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The matching of a "one-dimensional" numerical simulation and experiment results for low viscosity Newtonian and non-Newtonian fluids during fast filament stretching and subsequent break-up
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Hands-on Learning in Multiple Courses in Electrical and Computer Engineering
It has been reported that persistence rate of engineering students is relatively low. Several new pedagogical paradigms have been proposed to improve engineering education, such as the use of âhands-onâ tools to change the learning style in the engineering classroom to more engaging teaching pedagogies. An approach that is being used to engage and retain electrical and computer engineering students is the Analog Discovery board (ADB). The paper describes the hands-on learning experiences of students who used the ADB in multiple courses. The paper discusses (i) the various laboratory experiments and class projects performed by the students, (ii) the knowledge and skills learnt by the students and (iii) the lessons learnt by the instructors while introducing ADB into freshman and junior level courses in the electrical and computer engineering. Preliminary data indicate that students are benefiting from the use of the ADB. Students report increases in their interest in subject content, motivation to learn, and confidence in their ability to learn.Cockrell School of Engineerin
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Binary-mixture droplet evaporation: Lubrication approximation and coffee ring formation
This paper was presented at the 3rd Micro and Nano Flows Conference (MNF2011), which was held at the Makedonia Palace Hotel, Thessaloniki in Greece. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, Aristotle University of Thessaloniki, University of Thessaly, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute.In this paper the dynamics of an evaporating sessile droplet spreading on a horizontal substrate is reported. A mathematical model based on the lubrication approximation is developed accounting for Marangoni effect, contact line motion, and multi-component fluid. After validating the model through pure liquid spreading and evaporation, an extension of the model is performed on a binary component liquid in which composition changes occur during the drying process. Furthermore, the presence of particles in the fluid enables to retrieve the coffee-ring formation. A good qualitative and quantitative agreement between the model and experimental observations is found.This study is funded from ANR PANâH 2008 CATIMINHY project
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Prediction and evolution of drop-size distribution of an ultrasonic vibrating microchannel
This paper was presented at the 2nd Micro and Nano Flows Conference (MNF2009), which was held at Brunel University, West London, UK. The conference was organised by Brunel University and supported by the Institution of Mechanical Engineers, IPEM, the Italian Union of Thermofluid dynamics, the Process Intensification Network, HEXAG - the Heat Exchange Action Group and the Institute of Mathematics and its Applications.We report in this paper the evolution of a physically-based drop size-distribution coupling the Maximum Entropy Formalism and the Monte Carlo method to solve the distribution equation of a spray. The atomization is performed by a new Spray On Demand (SOD) device which exploits ultrasonic generation via a Faraday instability. The Modified Hamiltonâs principle is used to describe the fluid structure/interaction with a vibrating micro-channel conveying fluid excited by a pointwise piezoactuator. We combine to the
fluid/structure description a physically based approach for predicting the drop-size distribution within the framework of the Maximum Entropy Formalism (MEF) using conservation laws of energy and mass
coupling with the three-parameter generalized Gamma distribution. The prediction and experimental validation of the drop size distribution of a new Spray On Demand print-head is performed. The dynamic
model is shown to be sensitive to operating conditions, design parameter and physico-chemical properties of the fluid and its prediction capability is good. We also report on a model allowing the evolution of drop sizedistribution. Deriving the discrete and continuous population balance equation, the Mass Flow Algorithm is formulated taking into account interactions between droplets via coalescence. After proposing a kernel for
coalescence, we solve the time dependent drop size distribution using a Monte Carlo Method which is shown to be convergent. The drops size distribution upon time shows the effect of spray droplets coalescence
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On the modeling of viscoelastic droplet impact dynamics
This paper was presented at the 4th Micro and Nano Flows Conference (MNF2014), which was held at University College, London, UK. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute, ASME Press, LCN London Centre for Nanotechnology, UCL University College London, UCL Engineering, the International NanoScience Community, www.nanopaprika.eu.In this paper, a numerical modeling of the impact, spreading, and eventually rebound of a viscoelastic droplet is reported. The numerical model is based on the volume of fluid (VOF) method coupled with the FENE-CR constitutive equations, and accounts for both the surface tension and the substrate wettability. The FENE-CR constitutive equations are used to model the polymer solution, while taking advantage of its rheological characterization. The comparison is performed between droplets of Newtonian solvent and a monodisperse polymer solution. The droplet impact on both hydrophilic and superhydrophobic substrate is analyzed through a detailed analysis of the spreading diameter evolution. It is found that while the droplet kinematic phase seems independent of the substrate and fluids properties, the recoiling phase is highly related to all of them. In addition the model infers a critical polymer concentration above which the droplet rebound from a superhydrophobic substrate is suppressed. The simulation is of particular interest to ink-jet processing, and demonstrates the capability of the model to handle complex non-Newtonian droplet dynamics
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The matching of polymer solution fast filament stretching, relaxation, and break up experimental results with 1D and 2D numerical viscoelastic simulation
this work was supported by EPSRC grant number RG5560
Aspects cliniques et thérapeutiques des anomalies de la jonction pyélo-urétérale au CHU du point G
Cette Ă©tude a Ă©tĂ© faite pour analyser les aspects cliniques et thĂ©rapeutiques des anomalies de la jonction pyĂ©lo-urĂ©tĂ©rale. Etude transversale et descriptive portant sur 35 cas d'anomalies de la jonction pyĂ©lo-urĂ©tĂ©rale (AJPU) colligĂ©s au service d'Urologie du CHU du Point G durant une pĂ©riode de 4 ans (Janvier 2010 au DĂ©cembre 2014). Les donnĂ©es ont Ă©tĂ© recueillies sur les fiches d'enquĂȘte, les dossiers mĂ©dicaux et les registres du bloc. Les donnĂ©es sociodĂ©mographique, clinique et thĂ©rapeutique ont Ă©tĂ© saisies sur Microsoft Word 2007 et analysĂ©es sur Excel 2007 et SPSS 18.0. 35 cas d'AJPU ont Ă©tĂ© colligĂ©s en 4 ans. La moyenne d'Ăąge Ă©tait de 29,3 ans. La douleur lombaire Ă©tait le motif de consultation le plus frĂ©quent soit 40 %. 20 % des patients ont Ă©tĂ© en consultation pour la premiĂšre fois 10 ans d'Ă©volution symptomatique. Une destruction rĂ©nale avait Ă©tĂ© observĂ©e dans 28,6 %. Le couple Echographie + UIV a permis d'Ă©tablir le diagnostic chez 37,1 %. La complication lithiasique Ă©tait prĂ©sente chez 17,1 % des patients. 51,4 % des patients ont reçu une pyĂ©loplastie Ă ciel ouvert selon Anderson KUSS. L'anomalie de la jonction pyĂ©lo-urĂ©tĂ©rale dans notre Ă©tude a Ă©tĂ© caractĂ©risĂ©e par un retard de consultation avec des complications redoutables. La chirurgie Ă ciel ouvert a Ă©tĂ© le gold standard avec des rĂ©sultats satisfaisants. L'endopyĂ©loplastie, la cure de la jonction coelioscopique sont des chirurgies mini invasives non disponible chez nous mais Ă encourager et Ă intĂ©grer dans l'arsenal thĂ©rapeutique.Pan African Medical Journal 2016; 2
Kyste géant para-urétral feminine
Le kyste gĂ©ant para-urĂ©tral fĂ©minin infectĂ© est rarement rapportĂ© dans la littĂ©rature. Ce kyste est diffĂ©rent du diverticule sous urĂ©tral sur le plan clinique, diagnostique et thĂ©rapeutique. Sa pathogĂ©nie se confond avec celle des diverticules sous urĂ©traux. Son traitement nâest pas bien codifiĂ©, vu sa raretĂ©. Nous rapportons un cas atypique de kyste gĂ©ant para urĂ©tral infectĂ© chez une jeune femme de 26 ans. Le kyste Ă©tait symptomatique et la patiente a eu un traitement chirurgical. Nous discutons les aspects cliniques, diagnostiques et thĂ©rapeutiques de cette entitĂ© rare Ă travers une revue de la littĂ©rature.Key words: Kyste gĂ©ant, para urĂ©tral, fĂ©minin, chirurgi
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