Modeling and numerical simulation of secondary settlers: a method of lines strategy.

In this paper, attention is focused on a parabolic partial differential equation (PDE) modeling sedimentation in a secondary settler and the proper formulation of the problem boundary conditions (i.e., the conditions prevailing at the feed, clear water and sludge outlets).

Dynamic model of airway pressure drop.

A multipath model of the mechanical behaviour of healthy lungs subject to a plethysmographic test (close to quiet breathing conditions) has been developed, which includes the main physiological nonlinearities. This model is built on a symmetric branching scheme based on Weibel's data, and uses non-linear fluid equations for the upper and lower airways. The alveolar gas compression, the changes in airway dimensions related to lung volume and/or transmural pressure, and the respiratory swings in glottic aperture have been taken into account.

Thermal behavior of the constant volume body plethysmograph.

The thermal behavior of the constant volume body plethysmograph under the thermal effect of the patient and the thermostatic bag is modeled by two relations: the first is between the temperature in the box and the heat flux generated by the patient and the bag, and the second is between the pressure in the box and the same flux. When the heat flux evolves as a step function, the temperature and the pressure are characterized by four time constants, the theoretical values of which are functions of the heat transfer coefficients by natural convection between the faces of the walls, and the air inside and outside the box. Only two of these four theoretical constants can be experimentally measured with reasonable precision.