In this work cis-inositol, epi-inositol and myo-inositol carbonate were successfully synthesised and used for coordination studies. The preparation of cis-inositol was achieved by reduction of tetrahydroxybenzoquinone via hydrogenation with palladium hydroxide as the catalyst and was purified by chromatographic separation using Dowex resin. The synthesis of epi-inositol was achieved by the nitric acid oxidation of myo-inositol to form epi-inosose which was subsequently reduced by hydrogenation using palladium hydroxide as the catalyst. myo-Inositol was converted into its mono-orthoformate derivative and the equatorial hydroxy group was then protected as a tertiary-butyldimethylsilyl ether. The carbonate group was introduced onto this protected inositol and then the protecting groups were removed by acid hydrolysis. The coordination characteristics of four inositols, viz cis-inositol, epi-inositol, myo-inositol and myo-inositol carbonate with calcium, aluminium, gallium, lanthanum and samarium ions have been investigated. Interactions of the aluminate anion with epi-inositol and myo-inositol in deuterated sodium hydroxide were also investigated. Three methods were used in the study of complexation behaviour of these systems. namely, [superscript]13C NMR spectroscopy, HPLC and ion exchange chromatography. [superscript]13C NMR spectroscopy was found to be most useful for determining possible complexation behaviour of the inositols. Chemical shift changes of the resonance signals in the [superscript]13C NMR spectra on sequential addition of cations to solutions of the inositols at near neutral pH, have led to determination of possible coordination sites of the inositols. In general, large induced chemical shift changes have been interpreted to signify strong cation-inositol interaction at specific hydroxy groups. / Triaxial sites of the inositols have shown a preference to coordinate small ions with ionic size of at least 60 pin, smaller ions than this displayed very weak interactions. Likewise large ions (90-100 pm) imparted weak interactions on triaxial sites of the inositols. These large ions coordinated well with the axial-equatorial-axial sites of the inositols although it was observed that calcium ions appeared to form a 2:1 ligand:cation complex with cis-inositol at the triaxial site despite being a large cation (100 pm). The detection of complex formation by HPLC showed a possible formation of very stable complexes of epi-inositol complexes with calcium ions. However, a change of refractive index of the solution on sequential addition of the cation may have caused an interference in the results such that direct interpretation was not possible. Ion exchange chromatography provided the quickest guide on how strongly the inositols interact with a particular cation. However, determination of complex stoichiometry and or structure was not possible using this technique.

Algoritmos MPC implementam estratégias avançadas de controle adequada-mente aplicáveis a processos químicos complexos e multivariáveis. Recentemente, desenvolveram-se algoritmos MPC que possuem controle das saídas por faixas e estabilidade nominal baseados em horizonte infinito de predição. O objetivo principal deste trabalho é estender este tipo de algoritmo desenvolvendo um MPC de horizon-te infinito com referências para as entradas manipuladas e controle das saídas por funnel. Funnel é um dispositivo, particular aos algoritmos Honeywell RMPCT® (de horizonte finito), que suaviza as ações do controlador estabelecendo, a cada instan-te de amostragem, limites mais brandos para as saídas controladas que fogem às suas faixas. O algoritmo MPC de horizonte infinito aqui desenvolvido é analisado por simulação de um subsistema importante de uma planta de produção de alumina. Pe-las simulações, verificou-se de fato a suavidade das ações do controlador que dis-põe do funnel. Neste trabalho também se propõe, e se analisa por simulação, uma nova estrutura para o controlador RMPCT® que hoje atua sobre a planta. Uma vez que se mostrou interessante, essa nova estrutura, que inclui uma nova entrada ma-nipulada, poderá ser implementada na prática. / MPC algorithms are particularly suitable to implement advanced control strate-gies at complex and multivariable chemical processes. Recently, it has been devel-oped MPC algorithms with zone control and nominal stability, based on infinity pre-diction horizon. The main objective of this dissertation is to extend this type of algo-rithm by developing an infinity horizon MPC with targets to the manipulated inputs and funnel control. Funnel is a numerical device, particular to Honeywell RMPCT® algorithms (with finite horizon), that softens the controller actions by establishing, at each sampling instant, softer limits for the controlled outputs that escapes from its zones. The infinity horizon MPC algorithm developed here is analyzed by simulation of an important subsystem of an alumina production facility. According to the simula-tions, it was confirmed in fact the smoothness of the control actions produced by the funnel controller. In this work it is also proposed, and analyzed by simulation, a new structure for the RMPCT® controller that controls the plant nowadays. Since this new structure, which includes a new manipulated input, showed itself interesting, it can be implemented in practice.

Differential geometric nonlinear control of a multiple stage evaporator system of the liquor burning facility associated with the Bayer process for alumina production at Alcoa Wagerup alumina refinery, Western Australia was investigated.Mathematical models for differential geometric analysis and nonlinear controller synthesis for the evaporator system were developed. Two models, that were structurally different from each other, were used in the thesis for simulation studies. Geometric nonlinear control structure, consisting of nonlinear state feedback control laws and multi-loop single-input single-output proportional-integral controllers, were designed for the industrial evaporator system. The superiority of the geometric nonlinear control structure for regulatory control of the evaporator system was successfully demonstrated through computer simulations and real-time simulator implementation. The implementation trial has verified the practicality and feasibility of these type of controllers. It also re-solved some practical issues of the geometric nonlinear control structure for industrial control applications. In addition, the implementation trial also established a closer link between the academic nonlinear control theory and the industrial control practices.Geometric nonlinear output feedback controller, consisting of the geometric nonlinear control structure and reduce-order observer was proposed for actual plant implementation on the evaporator system on-site. Its superior performance was verified through computer simulations, but its feasibility on the evaporator system on-site has yet to be investigated either through simulator implementation or actual plant implementation. This investigation was not performed due to the time constraint on the preparation of this thesis and the inavailability of the plant personnel required for this implementation.Robust ++ / nonlinear control structures that are simple and computationally efficient have been proposed for enhancing the performance of geometric nonlinear controllers in the presence of plant/model mismatch and/or external disturbances. The robust nonlinear control structures are based on model error compensation methods. Robustness properties of the proposed robust nonlinear control structures on the evaporator system were investigated through computer simulations and the results indicated improved performance over the implemented geometric nonlinear controller in terms of model uncertainty and disturbance reductions.A software package was developed in MAPLE computing environment for the analysis of nonlinear processes and the design of geometric nonlinear controllers. This developed symbolic package is useful for obtaining fast and exact solutions for the analysis and design of nonlinear control systems. Procedures were also developed to simulate the geometric nonlinear control systems. It was found that MAPLE, while it is superior for the analyses and designs, is not viable for simulations of nonlinear control systems. This was due to limitation of MAPLE on the physical, or virtual, memory management. The use of both symbolic and numeric computation for solutions of nonlinear control system analysis, design and simulation is recommended.To sum up, geometric nonlinear controllers have been designed for an industrial multiple stage evaporator system and their simplicity, practicality, feasibility and superiority for industrial control practices have been demonstrated either through computer simulations or real-time implementation. It is hoped that the insights provided in this thesis will encourage more industry-based projects in nonlinear control, and thereby assist in closing the widening gap between academic nonlinear control theory and industrial control ++ / practice.Keywords: geometric nonlinear control, input-output linearization, multiple stage evaporator, robust geometric nonlinear control, control performance enhancement.

Algoritmos MPC implementam estratégias avançadas de controle adequada-mente aplicáveis a processos químicos complexos e multivariáveis. Recentemente, desenvolveram-se algoritmos MPC que possuem controle das saídas por faixas e estabilidade nominal baseados em horizonte infinito de predição. O objetivo principal deste trabalho é estender este tipo de algoritmo desenvolvendo um MPC de horizon-te infinito com referências para as entradas manipuladas e controle das saídas por funnel. Funnel é um dispositivo, particular aos algoritmos Honeywell RMPCT® (de horizonte finito), que suaviza as ações do controlador estabelecendo, a cada instan-te de amostragem, limites mais brandos para as saídas controladas que fogem às suas faixas. O algoritmo MPC de horizonte infinito aqui desenvolvido é analisado por simulação de um subsistema importante de uma planta de produção de alumina. Pe-las simulações, verificou-se de fato a suavidade das ações do controlador que dis-põe do funnel. Neste trabalho também se propõe, e se analisa por simulação, uma nova estrutura para o controlador RMPCT® que hoje atua sobre a planta. Uma vez que se mostrou interessante, essa nova estrutura, que inclui uma nova entrada ma-nipulada, poderá ser implementada na prática. / MPC algorithms are particularly suitable to implement advanced control strate-gies at complex and multivariable chemical processes. Recently, it has been devel-oped MPC algorithms with zone control and nominal stability, based on infinity pre-diction horizon. The main objective of this dissertation is to extend this type of algo-rithm by developing an infinity horizon MPC with targets to the manipulated inputs and funnel control. Funnel is a numerical device, particular to Honeywell RMPCT® algorithms (with finite horizon), that softens the controller actions by establishing, at each sampling instant, softer limits for the controlled outputs that escapes from its zones. The infinity horizon MPC algorithm developed here is analyzed by simulation of an important subsystem of an alumina production facility. According to the simula-tions, it was confirmed in fact the smoothness of the control actions produced by the funnel controller. In this work it is also proposed, and analyzed by simulation, a new structure for the RMPCT® controller that controls the plant nowadays. Since this new structure, which includes a new manipulated input, showed itself interesting, it can be implemented in practice.