Model-based robust H∞ control of a granulation process using Smith predictor with Reference updating

International audienceModel-based feedback control is developed for a continuous granulation process addressing the challengeof time delay and physics-based input-output constraints. The process plant is a multi-input multi-output (MIMO) linear model with time delay. A robust H ∞ controller is designed using the mixed sensitivity loop shaping design. A framework has been laid down to insure the robustness of the Smith predictor by incorporating the model mismatch as an additive uncertainty in the predictor’s structure. The control performance and robustness is assessed by simulations for regulation and reference tracking problems. We show significant performance gains by employing a Smith predictor and the technique of reference updating: The control is coping significantly better with time delay, physical constraints and model mismatch. The proposed control approach is more efficient as compared to other widely used methods such as model predictive control (MPC); obtaining a stable behaviour of the response and control effort while forcing them to remain within the desired bounds

Characterization of the Platinum Carbon Interface for Electrochemical Applications

Fuel cell catalysts suffer stability issues that are related to reaction-induced corrosion, catalyst sintering, and detachment. In the case of carbon-supported platinum nanoparticles, the stability can be improved by changing the carbon structure and tuning the metal–support interaction. The large structural and chemical variability of carbon offers a potential for improved electrochemical properties. However, a rational design of the metal–carbon interface requires knowledge about the relation between the carbon structure and the resulting platinum–carbon interaction. Using a variety of complementary analytical methods such as atomic scale imaging and local as well as integral spectroscopic tools in combination with different electrochemical aging protocols, we elaborate a relation between the structure-determined surface properties of the carbon and the resulting platinum–carbon interface. Atomic-scale imaging of the interface combined with electron spectroscopic methods enables distinction between different interaction types and associated bonding state and charge transfer properties. For the investigations, three differently structured industrial carbon support structures have been selected. The reported findings define solid criteria for a rational design of improved carbon supports