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Fully continuous drying can improve the production flexibility and throughput of tablets manufactured by wet granulation lines. A recently developed prototype incorporates a screw conveyor to a horizontal fluidized bed dryer for pharmaceutical particles. Research on advanced process control strategies led to the publication of a two-phase tanks-in-series framework to describe its dynamics. This paper calibrates the model to replicate the prototype behavior. A grey-box identification methodology estimates the empirical and uncertain parameters using experimental input-output data. The underlying assumptions are cross-validated with time-domain comparisons, output root mean square errors and confidence intervals. Results show that the model reproduces the observed trends in general and the discrepancies result from mechanical issues on the equipment.

The fluidized bed theory can be complex, especially for heterogeneous flow descriptions with bypasses, generally resulting in large differential and algebraic systems of equations. Consequently, their applicability to model-based process control is limited. In this work, a simplified homogeneous model for pharmaceutical batch drying is derived from the two-phase fluidization theory using physical insights and simplifying assumptions, reducing more than a hundred equations to five. A nonlinear model predictive controller with an internal model structure is designed from these simple equations, showing the simplicity of tuning and implementation. Parameters of the model are calibrated through nonlinear grey-box identification using pilot scale experimental data. The validation demonstrates that the proposed simplifications do not impair the ability to replicate the process dynamics adequately with experimental conditions similar to the ones used for calibration. Closed-loop results in simulation attest the robustness of this control strategy.

Batch fluidized bed drying is a common process for water removal in pharmaceutical particles. Multiple phenomenological models for this type of dryer are proposed in the literature, with ma...

Tablet manufacturing in the pharmaceutical industry involves batch fluidized bed drying for particle moisture removal. This paper introduces five approaches for moisture content monitoring, relying either on a complex phenomenological model or its simplified version. The first two soft sensors consist of open-loop estimators, i.e. they simply simulate the models fed by the manipulated variables. Three closed-loop moving horizon estimators based on the simplified model are also proposed for improved robustness. In the first one, the measurements of the inlet gas and particle temperatures feed back the soft sensor. The last two closed-loop observers additionally can take into account infrequent delayed moisture content measurements, such as at-line loss on drying analysis. A validation of the soft sensors is performed with experimental data collected on a pilot scale fluidized bed dryer. Results show that the closed-loop observer with the delayed moisture content measurements still has an accuracy that is equivalent (and sometimes better) than the complex phenomenological model.

The availability of reliable online moisture content measurements exploiting near-infrared (NIR) spectroscopy and chemometric tools allows the application of online control strategies to a wide range of drying processes in the pharmaceutical industry. In this paper, drying of particles with a pilot-scale batch fluidized bed dryer (FBD) is studied using a in-line NIR probe. A consolidated phenomenological state-space model of an FBD based on mass and energy balances is calibrated applying a nonlinear least-square identification to experimental data (grey-box modeling). Then, relying on the calibrated model, a nonlinear model predictive controller and a moving horizon state estimator are designed. The objective is to reach a specific particle moisture content setpoint at the end of the drying batch while decreasing cycle time and limiting particle temperature. A penalty term on the energy consumption can also be added to the usual tracking control cost function. Compared to a typical FBD operation in industry (mostly open-loop), it is shown that the drying time and the energy consumption can be efficiently managed on the pilot-scale process while limiting various operation problems like under drying, over drying, or particles overheating.

The bottleneck of pharmaceutical continuous wet granulation lines may often be the drying stage. The introduction of horizontal fluidized beds is currently contemplated to solve this issue, inter alia. However, it would require an appropriate process control system to reach and maintain over time the targeted residual moisture of the product. To support the endeavor of both the process and control designs, this paper develops a dynamic model with lumped parameters of a continuous horizontal fluidized bed dryer equipped with a screw conveyor. To this end, the framework makes use of a two-phase tanks-in-series configuration, thus taking into account expected gas bypasses (bubbles) and product axial mixing. Array programming and vectorized operations on each tank reactor allow solving equations explicitly at a low computational cost. Simulation results for calcium carbonate granules in a laboratory scale dryer are consistent with fluidization, drying and continuous reactor fundamentals.

Cet article décrit les interventions issues de la collaboration école-communauté, en contexte montréalais pluriethnique et socio-économiquement défavorisé, en vertu de leurs domaines d’activités, des objectifs qu’elles poursuivent, des populations visées et des stratégies déployées. Les interventions sont comparées pour les deux ordres d’enseignement. La composition des réseaux d’acteurs de même que les structures et la dynamique collaboratives à la base des interventions sont aussi décrites. L’article discute de la correspondance entre ces interventions et les orientations des politiques publiques en éducation et en santé en vertu desquelles elles sont déployées. Enfin, il interpelle les acteurs quant aux potentialités et limites de ce type d’interventions comme stratégie de soutien à la réussite éducative en contexte pluriethnique et défavorisé., This article describes interventions produced by school-community local networks in multi-ethnic and disadvantaged communities in Montréal. The fields of activity, objectives, targets and strategies are described and compared for elementary and secondary schools. School partners involved in school-community collaborations, and the structures and dynamics of their collaborative arrangements are also described. The discussion compares theses interventions with the objectives of Québec’s public education and health policies, which promote school-community collaboration. Finally, the article questions actors on possibilities and limits of these kinds of interventions in supporting school success in multiethnic and disadvantaged communities.

Cette étude de cas porte sur l’évaluation participative d’une intervention d’accompagnement scolaire à base communautaire dont le but est de favoriser la réussite scolaire en milieux montréalais socio-économiquement défavorisés. L’évaluation a été réalisée en collaboration étroite avec les acteurs de l’intervention. Elle compare les processus et les effets de l’intervention à base communautaire avec les interventions institutionnelles usuelles et montre les attributs innovants de l’intervention à base communautaire et son effet de protection auprès des enfants évoluant dans des conditions psychosociales adverses. Le partage de ces résultats motive la stabilisation du partenariat école—communauté à la base de l’intervention et la récurrence de son financement, et suscite la mobilisation de nouveaux partenariats sociaux.

This paper presents the evaluation of scale effects for the hydraulic conductivity, k, of a sand. Data were obtained using several methods at a site that was densely instrumented with piezometers within an area of about 100 m × 100 m. The 3.1–3.6 m thick sand deposit rests on a thick, nonfissured Champlain Sea clay deposit. At the small scale, local k values were obtained from the grain-size curves of sand samples and also from ground-penetrating radar surveys. At the intermediate scale, k values were obtained from field variable-head tests using piezometers. At the large scale, k values were obtained from pumping-test drawdowns in steady-state conditions. In this sand aquifer, the careful evaluations at three scales gave similar narrow distributions for the hydraulic conductivity, and therefore no scale effect is evidenced.Key words: hydraulic conductivity, sand, scale effect, gradation, monitoring well, pumping.

A new pulse shape for optical nonlinearity mitigation is proposed. Realistic simulations show that a 2.3 dB increase in launch power can be obtained, at no extra cost.

Electroblotting is a rapid and high-efficiency method of transferring DNA from gels to the variety of membranes available, in very short time frames when compared with capillary-blotting techniques and with much less preparation required. A simple apparatus made of two food savers, one dialysis membrane, one sponge, and two removable electrodes was used to transfer DNA molecules up to 21 kb, from agarose gels to nitrocellulose filters, in less than 30 min. A recombinant pAT153 plasmid carrying the human cytomegalovirus BamH I-P fragment (7.2 kb) was rapidly identified by hybridization, using our simplified transfer procedure.