Browsing by Subject "Dynamics."
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Item Metal ion assisted unimolecular decomposition of gaseous organometallic complexes : acquisition of reaction rate constants and dynamics of the dissociative mechanism.(2011-12-19) Villarroel, Otsmar J.; Bellert, Darrin Joseph, 1968-; Chemistry and Biochemistry.; Baylor University. Dept. of Chemistry and Biochemistry.Reaction rate constants have been acquired for the transition metal ion assisted decomposition of various organic molecules, and their deuterium labeled analogs in the gas phase. The metal ion activates organic bonds and mediates the formation of products. Thus, the transition metal cation lowers the bond activation energy requirements in these decomposition reactions making these systems model for catalysis. Catalytic reaction kinetics are not well understood and it is hoped that the resolved study of simpler catalytic models will further the development of the theoretical tools necessary to describe such mechanistic behavior at the molecular level. Reaction rate constants for these model systems are measured using a custom-built molecular beam apparatus. The clusters are formed under supersonic expansion conditions and are bound by the charge-dipole electrostatic interaction between a transition metal cation and a polar organic molecule. The unimolecular decomposition occurs upon laser photon absorption by the jet-cooled cluster yielding a stable neutral molecule and corresponding ion. This dissertation will focus on the unimolecular decomposition kinetics of the Co⁺-Acetone cluster and its deuterium labeled analog. Rate constants are measured at well resolved cluster internal energies. The kinetic isotope effect (KIE) for each measurement was determined. Results are compared to the similar Ni⁺-Acetone decomposition reactions, where the KIE was also measured. These two similar systems present rather different dissociation dynamics. Arguments based on the electronic structure of each ion explain this unique behavior between these similar systems. DFT calculations are made on most systems presented in this dissertation. The most likely geometries and relative energies of the reactants, intermediates and products are determined. Such information specifies aspects of the reaction coordinate and leads to suggestions of mechanisms. This was primarily applied in the final chapter of this dissertation where preliminary results of Ni⁺-assisted decomposition of cyclopentanone are presented. This system represents the group’s first study of a ring-opening reaction.Item System Identification: Time Varying and Nonlinear Methods(2010-07-14) Majji, ManoranjanNovel methods of system identification are developed in this dissertation. First set of methods are designed to realize time varying linear dynamical system models from input-output experimental data. The preliminary results obtained in a recent paper by the author are extended to establish a new algorithm called the Time Varying Eigensystem Realization Algorithm (TVERA). The central aim of this algorithm is to obtain a linear, time varying, discrete time model sequence of the dynamic system directly from the input-output data. Important results relating to concepts concerning coordinate systems for linear time varying systems are developed (discrete time theory) and an intuitive understanding of equivalent realizations is provided. A procedure to develop first few time step models is detailed, providing a unified solution to the time varying identification problem. The practical problem of identifying the time varying generalized Markov parameters required for TVERA is presented as the next result. In the process, we generalize the classical time invariant input output AutoRegressive model with an eXogenous input (ARX) models to the time varying case and realize an asymptotically stable observer as a byproduct of the calculations. It is further found that the choice of the generalized time varying ARX model (GTV-ARX) can be set to realize a time varying dead beat observer. Methods to use the developed algorithm(s) in this research are then considered for application to the identification of system models that are bilinear in nature. The fact that bilinear plant models become linear for constant inputs is used in the development of an algorithm that generalizes the classical developments of Juang. An intercept problem is considered as a candidate for application of the time varying identification scheme, where departure motion dynamics model sequence is calculated about a nominal trajectory with suboptimal performance owing to the presence of unstructured perturbations. Control application is subsequently demonstrated. The dynamics of a particle in a rotating tube is considered next for identification using the time varying eigensystem realization algorithm. Continuous time bilinear system identification method is demonstrated using the particle example and the identification of an automobile brake model.