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This dissertation, Electrical Chaoization and Its Application in Industrial Mixing by 叶霜, Shuang, Ye, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract of thesis entitled Electrical Chaoization and Its Application in Industrial Mixing Submitted by YE Shuang for the degree of Doctor of Philosophy at The University of Hong Kong in August 2007 Chaos, the phenomenon that deterministic systems sensitively depend on initial- condition, strikes at the determinism of the Newtonian view of the world. The study of chaos in motors has gone a long way from identification and avoidance to the application of electrical chaotic motion. The internal connection between mixing and chaos-that stretching and folding is the mechanism of mixing and also the fingerprint of chaos-suggests the improvement of mixing from the perspective of chaos. Mechanically chaoized mixers which make use of asymmetric geometrical design have been found to be more efficient than conventional mixers but suffer from fundamental complexity and inflexibility. This thesis presents the theory, analysis and implementation of electrically chaoized mixers. Theoretical analysis, computer simulation and experimental results are given to illustrate the proposed chaoization methods: time-delay feedback, tracking and destabilization control. The introduction of time-delay increases the number of system poles to infinite and the resulting system is thus prone to produce complicated dynamics. Through time-delay feedback, discrete chaotic maps can be utilized for the chaoization of continuous systems because of the internal connection between certain time-delay differential equations and difference equations. One of the limitations of the time-delay feedback control is that the analysis itself considers the no load or light load situation Electrical Chaoization and Its Application in Industrial Mixing ii only. Because the load is too complex for integrated analysis, the effect of the load is neglected. However, with the increase of load, the discrepancy between simulation prediction and the real motion increases. To make the current command more rigorous, tracking control is proposed which normalizes one of the state variables of a well studied chaotic model and sets it as the current reference. Destabilization control is another chaoization method which relocates the poles of the stable system to the right- half s plane by the linear feedback of all the state variables for a certain time and thus produces a positive average exponential rate of separation of two nearby initial conditions. Besides chaoization implemented through the tuning of control parameters of DC motors, the effect of permanent magnet (PM) flux as the bifurcation parameter for chaoization is discussed, as PMs play the most important role in both cost and performance of the permanent magnet synchronous motor (PMSM). To complete the puzzle, mixing effectiveness is verified by an acid-base neutralization reaction. Based on the same input power, mixing time needed to achieve homogeneity is compared. Chaotic mixing is found to be more efficient than constant speed mixing because of no formation of segregated regions, which is a major problem when mixing fluids with low Reynolds numbers. Finally, analysis and simulation on chaoization of single-phase shaded-pole motor based on combination of appropriate operating parameters is conducted. Chaotic motion may be utilized in washing machines and cooling fans which expands the application area into electrical household appliances. Electrical Chaoization and Its Application in Industrial Mixing i

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