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This paper reports the results of an experimental study conducied on a direct-drive motor t o evaluate the predicted behavior of selected friction models. W e focus the study t o the velocity response when torque ramp inputs are employed. Among the considered friction models, the dynamic friction model so-called LuGre model, captures very well the ezperimental behauior. As a consequence of the study, we derive a simple procedure t o determine the viscous and Coulomb friction from experimental velocity responses.

International audienceTwo wire mesh tomography devices and a liquid collector were used to study the influence of the gas flow rate on liquid distribution when fluids distribution on top of the reactor is ensured by a perforated plate. In opposition to most of the studies realized by other authors, conditions in which the gas has a negative impact in liquid distribution were evidenced. Indeed, the obtained results show that the influence of gas flow rate depends on the quality of the initial distribution, as the gas forces the liquid to “respect” the distribution imposed at the top of the reactor. Finally, a comparison between the two measuring techniques shows the limitations of the liquid collector and the improper conclusions to which its use could lead

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The main objective of this research is to find a simple and precise methodology for the stochastic generation of flow series having statistical behaviour similar to the registered or reconstituted historical series. The common statistical parameters are the mean, the variance, the auto- and cross-correlations, and, under particular conditions, the skewness coefficient. A procedure to disaggregate annual series to lower levels (monthly or seasonal) is also presented. Finally, the article describes the general computer model utilized for the synthetic generation. Key words: synthetic generation, flow series, disaggregation, computer model.