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NR 20140805

Thesis (MEng)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: The main purpose of the base metal refinery (BMR) as operated by Lonmin at their Western Platinum Ltd BMR, is to remove base metals – such as copper and nickel – from a platinum group metal (PGM) containing matte. The leaching processes in which this is done pose several challenges to the control of the process. The most significant of these is the slow dynamics of the process, due to large process units, as well as the continuously changing composition of the first stage leach residue, which is not measured on-line. This is aggravated by the fact that the exact leaching kinetics (and therefore the effect of the disturbances) are not understood well fundamentally. The slow process dynamics mean that controllers cannot be tuned aggressively, resulting in slow control action. The large residence times and off-line composition analyses of major controlled variables also mean that the effects of operator set point changes are visible only the following day, often by a different shift of operators. Dorfling (2012) recently developed a fundamental dynamic model of the pressure leach process at Lonmin‟s BMR. This dynamic model incorporates 21 chemical reactions, as well as mass and energy balances, into a system of 217 differential equations. The model provides a simulation framework within which improved control strategies can be investigated. The primary aims of this study are twofold. The first is to validate the model for the purpose of the investigation and development of control structure improvements. This is done by comparing the model to plant data, and adapting it if necessary. The second aim to reconsider the current control philosophy to the extent that is allowed by the model‟s determined validity. The current plant control philosophy aims to maintain a PGM grade of 65%, while the copper in the solids products of the second and third leaching stages should be below 25% and 3.5% by mass, respectively. Two areas of particular concern in this process that have been raised by Lonmin are the control of the temperature of the first compartment and the addition of pure sulphuric acid to control the acid concentration in the second stage leach. Dynamic plant data were used to calibrate the model, which was migrated from its received MATLAB platform to Simulink, to assist with control development. Flow rates were imported from the data, with some data values adapted for this purpose, due to mass balance inconsistencies. The outputs from the calibrated model were compared with corresponding data values. The model was found to be suitable for the investigation and development of the control structures of pressure, temperatures and inventories (termed basic regulatory control) and the acid concentration and solids fraction in the preparation tanks (termed compositional regulatory control). It was, however, found to be inadequate for the investigation and development of supervisory control, since it does not provide accurate compositional results. The leaching of copper is especially under-predicted, with the predicted copper concentration in the second stage product being approximately 46% lower than data values. The basic and compositional regulatory control structures were investigated. For each of these a base case was developed which aimed to represent the relevant current control structure, assuming optimal tuning. The variable pairings for the basic regulatory control were reconsidered using a method proposed by Luyben and Luyben (1997), since this part of the process does not permit the generation of a relative gain array (RGA) for variable pairing. The resulting pairing corresponds with Lonmin‟s current practice. Considering the temperature control of compartment 1, it was found that the addition of feed-forward control to the feedback control of the level of the flash tank improves the temperature control. More specifically, during an evaluation where the temperature‟s set point is varied up to 1%, the IAE of the temperature of compartment 1 was decreased with 7.5% from the base case, without disturbing the flash tank. The addition of feed-forward control allows for more rapid control and more aggressive tuning of this temperature, removing the current limit on ratio between the flash recycle stream and the autoclave feed. The compositional control was investigated for the second stage leach only, due to insufficient flow rate and compositional information around the third stage preparation tank. Variable pairing showed that three additive streams are available for the preparation tanks of the second and third stage leach to control the acid concentration and solids fraction in those tanks. Focussing on the second stage, the aim was to determine whether the acid concentration in the flash tank can be successfully controlled without the addition of pure acid to the tank. With four streams available around the second stage preparation tank to control its mass/level, the acid concentration and solids fraction, three manipulated variables were derived from these streams. The resulting pairings were affirmed by an RGA. Control loops for the control of acid concentration and solids fraction in the flash tank were added as cascade controllers, using the preparation tank‟s control as secondary loops. The added compositional control was evaluated in two tests. The first of these entailed the adding of typical disturbances, being the flash recycle rate, the solids and water in the feed to the second stage preparation tank and the acid concentration in copper spent electrolyte. In the second test the control system was tested for tracking an acid concentration set point. It was found that the cascade structure controls the acid concentration in the flash tank less tightly than the base case (with an IAE that is 124% and 80.6% higher for the two tests), but that it decreases the variation of solids fraction (lowering the IAE with 40.8% with the first test) in the same tank and of the temperature in the first compartment (lowering the IAE with 73.6% in the second test). It is recommended that the relative effects of these three variables on leaching behaviour should be investigated with an improved model that is proven to accurately predict leaching reactions in the autoclave. / AFRIKAANSE OPSOMMING: Die hoofdoel van die basismetaal-raffinadery (BMR), soos dit bestuur word deur Lonmin by hulle Western Platinum Ltd BMR, is om basismetale – soos koper en nikkel – te verwyder uit 'n mat wat platinum groep metale (PGM) bevat. Die logingsprosesse waarin dit gedoen word hou talle uitdagings in vir die beheer van die proses. Die mees beduidende hiervan is die proses se stadige dinamika, wat veroorsaak word deur groot proseseenhede, sowel as die deurlopend veranderende samestelling van die eerste stadium residue (wat nie aanlyn gemeet word nie). Dit word vererger deur die feit dat die presiese logingskinetika (en daarom ook die effek van versteurings) nie fundamenteel goed verstaan word nie. Die stadige dinamika beteken dat die beheerders die aggressief verstel kan word nie, en dit lei tot stadige beheeraksies. Die groot verblyftye en aflyn samestellingsanalises van die belangrikste beheerde veranderlikes beteken dat die gevolge van 'n operateur se stelpunt veranderinge slegs die volgende dag sigbaar is – dikwels in die skof van 'n ander operateur. Dorfling (2012) het onlangs 'n fundamentele, dinamiese model van die drukloog proses by Lonmin se BMR ontwikkel. Hierdie dinamiese model inkorporeer 21 chemiese reaksies, sowel as massa- en energiebalanse, in ‟n stelsel van 217 differensiaalvergelykings. Die model bied 'n simulasie-raamwerk waarbinne verbeterde beheerstrategieë ondersoek kan word. Die hoofdoel van hierdie studie is tweeledig. Die eerste hiervan is om die model te valideer vir die ondersoek en ontwikkelling van beheerstruktuur verbeteringe. Dit is gedoen deur die model met aanlegdata te vergelyk en dit aan te pas, indien nodig. Die tweede doel is om die huidige beheerfilosofie te heroorweeg tot op 'n punt wat toegelaat word deur die bepaalde geldigheid van die model. Die huidige beheerfilosofie van die aanleg mik om 'n gehalte van 65% te handhaaf, terwyl die koper in die vastestof produk van die tweede en derde logingsstadia onderskeidelik onder 25% en 3.5% op 'n massa basis moet wees. Twee probleem-areas, soos ge-opper deur Lonmin, is die beheer van die temperatuur in die eerste kompartement en die byvoeging van suiwer swaelsuur om die suurkonsentrasie van die tweede stadium te beheer. Dinamiese aanlegdata is gebruik om die model te kalibreer. Hierdie model is van die oorspronklike MATLAB platform na Simulink gemigreer, ten einde beheerontwikkelling te vergemaklik. Vloeitempo's is van die data af ingevoer na die model toe, met sekere data waardes wat aangepas is vanweë massabalans inkonsekwenthede. Die uitsette van die gekalibreerde model is met die ooreenstemmende data waardes vergelyk. Daar is bevind dat die model geskik is vir die ondersoek en ontwikkelling van die beheer van druk, temperature en tenks (basiese reguleringsbeheer), sowel as die beheer van suurkonsentrasies en vastestoffraksies in die bereidingstenks (reguleringsbeheer van die samestelling). Daar is egter bevind dat die model nie geskik is vir die ondersoek en ontwikkelling van toesigbeheer nie, aangesien dit nie akkurate samestellingsresultate genereer nie. Die voorspelde loging van koper is veral te laag, met die model wat koperkonsentrasies vir die tweede stadium voorspel wat ongeveer 46% laer is as ooreenstemmende data waardes. Die basiese en samestelling reguleringsbeheer strukture is ondersoek. Vir elkeen is ‟n basisgeval ontwikkel wat poog om die huidige beheerstruktuur te verteenwoordig, met optimale verstellings aanvaar. Die paring van veranderlikes vir die basiese reguleringsbeheer is heroorweeg met deur middel van ‟n metode wat deur Luyben en Luyben (1997) voorgestel is, aangesien hierdie deel van die proses nie die opstel van ‟n relatiewe winsmatriks (RWM) vir die paring toelaat nie. Die uiteindelike paring stem ooreen met Lonmin se huidige praktyk. Met die heroorweging van die temperatuurbeheer van kompartement 1 is daar bevind that die byvoeging van vooruitvoer beheer by die terugvoerbeheer van die flitstenk die temperatuurbeheer verbeter. Meer spesifiek het die IAE van hierdie temperatuur met 7.5% verlaag van die basisgeval af nadat die temperatuur se stelpunt tot met 1% gevariëer is – sonder om die flitstenk te versteur. Die byvoeging van vooruitvoer beheer laat vinniger beheer en meer aggressiewe verstellings van die temperatuur toe, aangesien die huidige beperking op die verhouding tussen die flitsstroom en die outoklaaf voer verwyder word. Die samestellingsbeheer is slegs ondersoek in die geval van die tweede loogstadium as gevolg van onvoldoende vloeitempo- en samestellingsinligting om die bereidingstenk van die derde stadium. Die paring van veranderlikes het gewys dat drie voerstrome onderskeidelik beskikbaar is vir beide die bereidingstenks van die tweede en derde stadia, om die suurkonsenstrasies en vastestoffraksies in hierdie tenks te beheer. Met die fokus op die tweede stadium was die doel om te bepaal of die suurkonsentrasie in die flitstenk suksesvol beheer kan word sonder dat suiwer suur by hierdie tenk gevoeg word. Met vier strome beskikbaar rondom die bereidingstenk van die tweede stadium om die massa/vlak, die suurkonsentrasie en die vastestoffraksie te beheer, is drie manipuleerde veranderlikes vanuit hierdie strome afgelei. Die uiteindelike paring is bevestig deur 'n RWM. Beheerlusse is ingevoeg vir die beheer van die suurkonsentrasie en vastestoffraksie in die flitstenk, met die bereidingstenk se beheer wat dien as sekondêre lusse in kaskadebeheer. Die kaskadebeheer is geëvalueer in twee toetse. Die eerste hiervan behels die invoer van tipiese versteurings, soos die vloeitempo van die flitsstroom, die vastestof en water in die voer na die tweede stadium se bereidingstenk en die suurkonsentrasie in die gebruikte elektroliet. In die tweede toets is die vermoë van die beheerstelsel om 'n suurkonsentrasie stelpunt te volg getoets. Daar is bevind dat die kaskadestruktuur die suurkonsentrasie minder nougeset beheer as die basisgeval (met 'n IAE wat 124% en 80.6% hoër is vir die twee toetse), maar dat dit die variasie in die vastestoffraksie in dieselfde tenk (40.8% vermindering van die IAE in die eerste toets) en in die temperatuur van die eerste kompartement (73.6% vermindering van die IAE in die tweede toets) beduidend verminder. Daar word aanbeveel dat die relatiewe effekte van hierdie drie veranderlikes op logingsoptrede ondersoek moet word, met die gebruik van 'n model wat logingsreaksies in die outoklaaf akkuraat voorspel.

O modelo brasileiro de governança corporativa é caracterizado pela concentração na estrutura de propriedade e controle da maioria das companhias de capital aberto. Nesse contexto, a literatura acadêmica aponta a existência de um impacto positivo e outro negativo desse acúmulo de ações pelo (s) controlador (es) sobre o desempenho corporativo, conhecidos, respectivamente, como: efeito-incentivo (ou alinhamento); e efeito-entrincheiramento. Diversos estudos empíricos nacionais e internacionais testaram essas duas hipóteses, entretanto, dada a divergência entre seus resultados, ainda não há evidências conclusivas sobre a influência da concentração de propriedade sobre o valor das organizações. Diante desse problema, a presente dissertação teve dois objetivos principais: buscar possíveis determinantes corporativos da concentração de propriedade e controle, isto é, averiguar seu caráter endógeno (Parte 1); e testar se essa concentração influencia o valor de mercado corporativo (Parte 2). Para tanto, foi utilizado um painel não balanceado para o período de 2001 a 2010, composto por 237 empresas brasileiras não financeiras de capital aberto. Com o intuito de mitigar possíveis fontes de endogeneidade como a omissão de variáveis, o efeito feedback e a causalidade reversa, foram empregados modelos dinâmicos de regressão linear múltipla, estimados pelo Método dos Momentos Generalizado Sistêmico (MMG-Sis). Os resultados da primeira parte do estudo não sustentam a hipótese de que o caráter da estrutura de propriedade e controle é endógeno. Já na segunda parte da pesquisa, o efeito-incentivo foi captado pelo valor de mercado corrigido do total de ações do maior acionista. Enquanto a concentração no direito de voto e a separação entre propriedade e controle capturaram o efeito-entrincheiramento. / The Brazilian model of corporate governance is characterized by the ownership and control concentration of most publicly traded companies. In this context, the academic literature points to the existence of a positive and a negative impacts of this shares accumulation by controller (s) on corporate performance, known respectively as incentive effect (or alignment) and entrenchment effect. Several Brazilian and international empirical studies have tested these two hypotheses, however, given the divergence of their results, until now there is no conclusive evidence about the influence of ownership concentration on firm value. Faced with this problem, this thesis had two main goals: search for possible determinants of ownership and control concentration, i.e., test its endogenous character (Part 1); and test whether this concentration influences corporate market value (Part 2). For this purpose, an unbalanced panel for the period of 2001 to 2010 was used, comprising 237 Brazilian non-financial publicly traded companies. In order to mitigate potential sources of endogeneity like missing variables, reverse causality and feedback effect, dynamic models of multiple linear regression were employed, estimated by System Generalized Method of Moments (GMM-Sys). The results of the study\'s first part do not support the hypothesis that the character of ownership and control structure is endogenous. In the second part of the research, the incentive effect was captured by adjusted market value of total shares of the largest shareholder. While the voting right concentration and the separation of ownership and control captured the entrenchment effect.

All future Extremely Large Telescopes (ELTs) will be segmented. However, as their size grows, they become increasingly sensitive to external disturbances, such as gravity, wind and temperature gradients and to internal vibration sources. Maintaining their optical quality will rely more and more on active control means. This thesis studies active optics of segmented primary mirrors, which aims at stabilizing the shape and ensuring the continuity of the surface formed by the segments in the face of external disturbances. The modelling and the control strategy for active optics of segmented mirrors are examined. The model has a moderate size due to the separation of the quasi-static behavior of the mirror (primary response) from the dynamic response (secondary, or residual response). The control strategy considers explicitly the primary response of the telescope through a singular value controller. The control-structure interaction is addressed with the general robustness theory of multivariable feedback systems, where the secondary response is considered as uncertainty. Scaling laws allowing the extrapolation of the results obtained with existing 10m telescopes to future ELTs and even future larger telescopes are addressed and the most relevant parameters are highlighted. The study is illustrated with a set of examples of increasing sizes, up to 200 segments. This numerical study confirms that scaling laws, originally developed with simple analytical models, can be used in confidence in the preliminary design of large segmented telescopes.

An important and challenging problem that Process Engineers frequently encounter is the determination of appropriate control structures that minimize the loss of process performance under the effect of uncertainties. This can be achieved by selecting subsets of controlled and manipulated variables and designing their interconnection (controller synthesis). This is known as the Control Structure Selection Problem (CSSP) In this Thesis, a systematic optimization methodology, based on the back-off concept proposed by Prof J. D. Perkins and co-workers, is presented for the CSSP. The proposed formulation offers the following improvements: a) improves the accuracy of calculations and b) reduces computational time and effort. Specifically, the error involved in the approximation of the nonlinear constraint that defines the magnitude of the back-off vector (needed for control structure selection) is reduced by the introduction of a more accurate linear approximation. In addition, the methodology is able to track the effect of simultaneously occurring disturbances at the same time and estimate their worst impact on process economics. The reduction of computational time is achieved by eliminating the state variables from the final formulation. In this way, the number of equations needed for the CSSP solution is significantly reduced and allows the algorithm to locate the solution faster without affecting the performance. The proposed methodology is firstly applied in a classical distillation column (medium scale) and in a complex and highly nonlinear reactive distillation column (large scale). The results obtained from these case studies made the way for the application of the methodology on the plantwide problem of the benchmark Vinyl Acetate monomer production plant in order to demonstrate the benefits of the proposed algorithm. / Η παρούσα εργασία παρουσιάζει μια συστηματική μεθοδολογία για την εύρεση βέλτιστων δομών ρύθμισης σε συστήματα μεγάλης κλίμακας, όπως για παράδειγμα ολοκληρωμένες μονάδες παραγωγής και βασίζεται στην ελαχιστοποίηση των επιπτώσεων των διαταραχών στην οικονομική απόδοση μιας διεργασίας. Το κύριο στοιχείο της μεθοδολογίας είναι το διάνυσμα υποχώρησης από τους ενεργούς περιορισμούς (μ), το οποίο προτάθηκε από τον Prof. J.D. Perkins και την ερευνητική του ομάδα. Η προτεινόμενη μεθοδολογία ενσωματώνει τα κύρια χαρακτηριστικά της μεθοδολογίας του διανύσματος (μ) και παρουσιάζει μια σειρά βελτιώσεων με στόχο τον περιορισμό των μειονεκτημάτων που απέτρεπαν την εφαρμογή της σε συστήματα μεγάλης κλίμακας. Οι βελτιώσεις επικεντρώνονται σε δύο ζητήματα: α) αύξηση της ακρίβειας των υπολογισμών και β) μείωση του υπολογιστικού φόρτου και χρόνου. Η αύξηση της ακρίβειας των υπολογισμών εντοπίζεται στην κατασκευή ενός βελτιωμένου προσεγγιστικού προβλήματος για την κατασκευή κάτω φραγμάτων για τη βέλτιστη λύση. Η βασική ιδέα πίσω από τη προτεινόμενη βελτίωση βασίζεται στη προσέγγιση των μη γραμμικών όρων που εμφανίζονται με ένα σύνολο γραμμικών εξισώσεων. Επίσης για πιο ακριβείς υπολογισμούς, εξετάζεται κάθε διαταραχή ξεχωριστά σε ένα εύρος συχνοτήτων και στη συνέχεια η μέγιστη επίδραση της καθεμίας χρησιμοποιείται από τον αλγόριθμο έτσι ώστε να υπολογιστεί η μέγιστη δυνατή επίπτωση τους στην οικονομική απόδοση της διεργασίας Η μείωση του υπολογιστικού φόρτου και χρόνου επιτυγχάνεται μέσω της απαλοιφής των μεταβλητών κατάστασης. Με αυτό τον τρόπο, ο αριθμός των εξισώσεων που απαιτείται για την επίλυση του προβλήματος μειώνεται σημαντικά και εντοπίζει τη βέλτιστη λύση σε μικρότερο αριθμό επαναλήψεων της μεθόδου, γεγονός που επιτρέπει την εφαρμογή της σε προβλήματα μεγάλης κλίμακας. Τέλος, η προτεινόμενη μεθοδολογία έχει εφαρμοστεί σε δύο αποστακτικές στήλες και τα αποτελέσματα άνοιξαν το δρόμο για την εφαρμογή της μεθόδου σε μια μονάδα παραγωγής οξικού μεθυλεστέρα, όπου τα πλεονεκτήματα της μεθόδου είναι περισσότερο ορατά και πρακτικά χρήσιμα.

No description available.

O modelo brasileiro de governança corporativa é caracterizado pela concentração na estrutura de propriedade e controle da maioria das companhias de capital aberto. Nesse contexto, a literatura acadêmica aponta a existência de um impacto positivo e outro negativo desse acúmulo de ações pelo (s) controlador (es) sobre o desempenho corporativo, conhecidos, respectivamente, como: efeito-incentivo (ou alinhamento); e efeito-entrincheiramento. Diversos estudos empíricos nacionais e internacionais testaram essas duas hipóteses, entretanto, dada a divergência entre seus resultados, ainda não há evidências conclusivas sobre a influência da concentração de propriedade sobre o valor das organizações. Diante desse problema, a presente dissertação teve dois objetivos principais: buscar possíveis determinantes corporativos da concentração de propriedade e controle, isto é, averiguar seu caráter endógeno (Parte 1); e testar se essa concentração influencia o valor de mercado corporativo (Parte 2). Para tanto, foi utilizado um painel não balanceado para o período de 2001 a 2010, composto por 237 empresas brasileiras não financeiras de capital aberto. Com o intuito de mitigar possíveis fontes de endogeneidade como a omissão de variáveis, o efeito feedback e a causalidade reversa, foram empregados modelos dinâmicos de regressão linear múltipla, estimados pelo Método dos Momentos Generalizado Sistêmico (MMG-Sis). Os resultados da primeira parte do estudo não sustentam a hipótese de que o caráter da estrutura de propriedade e controle é endógeno. Já na segunda parte da pesquisa, o efeito-incentivo foi captado pelo valor de mercado corrigido do total de ações do maior acionista. Enquanto a concentração no direito de voto e a separação entre propriedade e controle capturaram o efeito-entrincheiramento. / The Brazilian model of corporate governance is characterized by the ownership and control concentration of most publicly traded companies. In this context, the academic literature points to the existence of a positive and a negative impacts of this shares accumulation by controller (s) on corporate performance, known respectively as incentive effect (or alignment) and entrenchment effect. Several Brazilian and international empirical studies have tested these two hypotheses, however, given the divergence of their results, until now there is no conclusive evidence about the influence of ownership concentration on firm value. Faced with this problem, this thesis had two main goals: search for possible determinants of ownership and control concentration, i.e., test its endogenous character (Part 1); and test whether this concentration influences corporate market value (Part 2). For this purpose, an unbalanced panel for the period of 2001 to 2010 was used, comprising 237 Brazilian non-financial publicly traded companies. In order to mitigate potential sources of endogeneity like missing variables, reverse causality and feedback effect, dynamic models of multiple linear regression were employed, estimated by System Generalized Method of Moments (GMM-Sys). The results of the study\'s first part do not support the hypothesis that the character of ownership and control structure is endogenous. In the second part of the research, the incentive effect was captured by adjusted market value of total shares of the largest shareholder. While the voting right concentration and the separation of ownership and control captured the entrenchment effect.

Distributed computing systems (DCS) host a wide variety of enterprise applications in dynamic and uncertain operating environments. These applications require stringent reliability, availability, and quality of service (QoS) guarantee to maintain their service level agreements (SLAs). Due to the growing size and complexity of DCS, an autonomic performance management system is required to maintain SLAs of these applications. A model-based autonomic performance management structure is developed in this dissertation for applications hosted in DCS. A systematic application performance modeling approach is introduced in this dissertation to define the dependency relationships among the system parameters, which impact the application performance. The developed application performance model is used by a model-based predictive controller for managing multi-dimensional QoS objectives of the application. A distributed control structure is also developed to provide scalability for performance management and to eliminate the requirement of approximate behavior modeling in the hierarchical arrangement of DCS. A distributed monitoring system is also introduced in this dissertation to keep track of computational resources utilization, application performance statistics, and scientific application execution in a DCS, with minimum latency and controllable resource overhead. The developed monitoring system is self-configuring, self-aware, and fault-tolerant. It can also be deployed for monitoring of DCS with heterogeneous computing systems. A configurable autonomic performance management system is developed using modelintegrated computing methodologies, which allow administrators to define the initial settings of the application, QoS objectives, system components’ placement, and interaction among these components in a graphical domain specific modeling environment. This configurable performance management system facilitates reusability of the same components, algorithms, and application performance models in different deployment settings.

<p> Control structure design is an essential step in control system synthesis and has big impact on achievable closed-loop performance. This thesis develops a systematic approach of selecting optimal control structures based on closed-loop dynamic performance and other criteria, such as integrity.</p> <p> The main contribution of this thesis is a rigorous mathematical formulation for control structure design problem that includes full closed-loop transient analysis with additional integrity requirement. The multi-objective framework is extendable so that different control performance objectives can be easily added. Unique process requirements and engineer inputs can be taken into account as additional constraints. The proposed formulation is a Mixed Integer Nonlinear Programming (MINLP) with complementarity constraints. The research scope is limited to linear process models and linear controller algorithms.</p> <p> The tailored solving strategy that makes this challenging problem computationally tractable is introduced in this thesis. The modified Branch and Bound algorithm takes advantage of the special problem structure by using control knowledge to generate valid lower bound efficiently. Prior knowledge can be cooperated as heuristic tuning parameters to guide the solving process so that a reasonably good solution can be found early in the solving process. The complexity study shows the solving strategy can attack design problem size up to 8x8. Considering the percentage of good structures needing evaluation will decrease with problem size even larger problems will be tractable.</p> <p> The common control structures in process industries, such as square and nonsquare Single-Input-Single-Output (SISO) loop pairing using PID controller and block-centralized structure using Model Predictive Controller (MPC), are addressed in this thesis. The usefulness of this research has been demonstrated by several case studies, include Tennessee Eastman problem. The proposed methodology finds a physically sound pairing with good performance for Tennessee Eastman problem in less than one hour, while several off-the-shelf NLP, MINLP and global solvers cannot find a solution in five days.</p> / Thesis / Doctor of Philosophy (PhD)