Nonlinear Dynamics and Control of Complex Patterns in Distributed Chemical Systems

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Abstract - Chang - 9522277 Coherent Structures, like fronts and pulses drive the dynamics in reactor instabilities and transients, fast-igniting catalytic converters, reactive chromatographs and electrophoresis devices, ceramic synthesis, etc. The PI has established empirically that such structure dynamics are low-dimensional and hence readily controllable and has developed the theoretical tools and computer software to capture the nonlinear dynamics and implement nonlinear feedback control, typically with a video sensor. The PI plans to use his theory to classify and decipher all coherent-structure dynamics involving fronts, pulses, spiral waves, etc. in a general framework. Guided by the theory, an scheme will be developed to estimate the spectra of thermal fronts and concentration pulses from IR thermal and video imaging. The scheme will use multi-resolution windowed wavelets to compress the pixel data during estimation and feedback control. This scheme will then will be used to study and control several coherent-structure driven dynamics with important potential applications. Thermal flickering control with multiple hot spots and thermal fronts will be attempted. A feedback control scheme will be developed to stabilize thermal fronts in a catalytic converter during transient driving conditions. Interfacial waves on a wetted- wall column will be structured through feedback control to maximize heat/mass transfer in pollutant scrubbing processes. A video-feedback control experiment will be designed to control the speed, width and integrity of a concentration pulse in a miniature reactive chromatograph to enhance detectability and separation.