F. Bertrand

MeV, which is 2-3 MeV below the well-known El giant dipole resonance. The spin of this resonance is usually deduced by comparing measured differential cross sec-tions with predictions of thedistorted-wave Born approximation(DWBA) normalized to transition ...

Measurements of the analyzing power and the differential cross section in the nuclear continuum for the reaction 58 Ni (p, p′) initiated by 60-MeV polarized protons provide strong evidence for a quadrupole (E 2) interpretation for the giant resonance at E x≈ 63/A ...

A vibrational collective model has been used to analyze 15 bound states in 40Ca excited by inelastic scattering of 500 MeV polarized protons. It is shown that for those states which have surface peaked charge transition densities the collective model describes the shape and magnitude of the angular distributions quite well. The hadronic deformation lengths extracted are shown to be

ABSTRACT Over the past fifteen years or so, computer modeling has helped gain insight into the dynamics of granular mixing for a broad range of applications in the chemical, food, cosmetic and pharmaceutical industries. In particular, there is a large body of work in the ...

Marc Lemieux 1 , Francois Bertrand 1 , Jamal Chaouki 1 , and Patrick Gosselin 2 . (1) Department of Chemical Engineering, École Polytechnique de ... one of the most common tumbling blenders used to mix granular materials in the pharmaceutical industry (eg Alexander et al ...

Salt weathering is a major cause of deterioration of rocks and building materials. The precise mechanisms of why certain salts (e.g., sodium sulfate) cause more damage than others (e.g., sodium chloride) under the same environmental conditions still remain elusive. Here we show that for sodium sulfate, the existence of hydrated and anhydrous crystals and specifically their kinetics of crystallization are

We study the flow of a typical thixotropic material subjected to very different deformation histories (squeeze, shear, and extrusion) with either local (proton NMR and magnetic resonance imaging) or macroscopic measurements after different times of rest. Specifically, we measure the velocity fields and the spin-spin NMR relaxation of the material after different flow histories. The relaxation data exhibits a long relaxing component revealing information about the reversible microstructural evolution of the sample during aging-rejuvenation cycles. We show that for each deformation process, the evolution of the viscosity during the solid-liquid transition is similar by a factor related to the initial state of the material. Moreover, results examining the impact of the rate at which the deformation is imposed suggest that the state of the material during this transition may be described by a single parameter reflecting the average size and deformation of the material's flocs. These results also show that localization of flow occurs as a result of a progressive differential evolution of the material in different regions of the flow, and thus are determined by the boundary conditions of the flow.

... 1c). In particular, the formation of a heap of powder downstream from the blade impeller was ... Many such methods have been developed over the years and can be divided into two ... The three-dimensional (3D) simulation of granular flow in a mixing system generally implies the ...

ABSTRACT Considerable amount of experimental work has been performed to elucidate the behavior of granular flow inside a rotating drum and it has yet to be clearly understood. However, a majority of these investigations have involved spherical or nearly spherical particles. The extent of the experiments involving non spherical particles previously carried out was limited by the experimental technique used for the investigation or the inability to single out the effect of the particle shape. In this work, the radioactive particle tracking technique (RPT) is adapted to follow large non spherical particles inside a rotating drum. The particles consist of pharmaceutical tablets containing a suitable compound, thus enabling their use as a tracer particle. Three crucial aspects of particle dynamics inside a rotating drum are studied: residence time in the active and passive layers, mixing and segregation, as well as axial dispersion. The results obtained for non spherical particles are compared to those which would be predicted using models developed for spherical of nearly spherical particles. For the different shapes studied in this work, it is found that particles having an aspect ratio greater than two can lead to significant deviations in velocity profile and residence time In addition, the mixing of different shaped particles is observed to lead to unexpected core segregation patterns. Lastly, it is found that the non-spherical particle higher degree of spatial orientation in the active layer leads to a lower axial dispersion coefficient than the ones obtained with spherical particles.

Abstract: Proper design and operation of powder mixers is critical for the production of high quality pharmaceutical drugs. Successful design can only be achieved from a comprehensive knowledge of solid dynamic in such mixers. Discrete Element Methods (DEM) have been found ...

ABSTRACT The mechanisms of segregation in solids mixing, even in simple rotating drums, are not clearly understood. Although most past studies have focused on binary mixtures, this work investigates the effect of polydispersity on granular flow, mixing, and segregation in a rotating drum operated in rolling regime through particle trajectories obtained from the radioactive particle tracking technique. Velocity profiles, radial segregation, and axial dispersion coefficients for monodisperse and polydisperse systems of glass beads are analyzed with respect to rotational speed and particle size. A model is introduced to predict the residence times along streamlines and evaluate the rate at which the material renews at the free surface and within the inner layers of the bed. Our results reveal similar velocity profiles and residence times for monodisperse and polydisperse systems. They also indicate that the particles distribute along the radial direction of the drum, although not necessarily in a core/shell configuration. © 2012 American Institute of Chemical Engineers AIChE J, 59: 1894–1905, 2013