Atualmente, o HLB é considerado a principal doença que acomete as plantas cítricas. Diante desse fator, pesquisas por cultivares resistentes a esta doença são necessárias. A transformação genética via Agrobacterium, juntamente com o uso de plantas modelos, tem sido uma alternativa para verificação do funcionamento dos genes em resposta a patógenos, isto porque as plantas modelos possuem como característica ciclo de vida curto e alto poder de regeneração. Assim sendo, objetivou-se com o presente trabalho, a transformação genética via Agrobacterium tumefaciens, de tomate Micro-Tom (Solanum lycopersicum L.) e de laranja doce, com os genes que codificam as proteínas PR-8 e CDR-1, isolados a partir de Citrus simensis. Os cotilédones provenientes de sementes germinadas in vitro de tomate Micro-Tom foram utilizados como fonte de explante para os experimentos de transformação genética com os genes PR-8 e CDR-1. Esses explantes foram subcultivados até o aparecimento de brotos regenerantes e posteriormente plantas transgênicas, as quais foram aclimatizadas e levadas a casa-de-vegetação. A transgenia foi confirmada por PCR e o número de inserções do gene por Southern blot. As plantas foram cultivadas até a obtenção da geração T1. Simultaneamente, foram realizados experimentos de transformação genética em segmentos de epicótilo, provenientes de sementes de laranja ‘Hamlin’ germinadas in vitro, com o gene CDR-1, a fim de se obter plantas transgênicas e sua caracterização. Paralelamente, foi realizada a construção da curva padrão pela análise de qPCR para identificação de Pseudomonas syringae pv. tomato. Foram obtidas treze plantas transgênicas de tomate Micro-Tom com o gene PR-8 e três com o gene CDR-1. As eficiências de transformação foram em torno de 0,38 a 1,98%. Três plantas de tomate Micro-Tom transgênicas com o gene PR-8 foram caracterizadas por Southern blot e o número de inserções variou de 1 a 3. Dezenove plantas transgênicas de laranja ‘Hamlin’ com o gene CDR-1 foram obtidas através dos experimentos de transformação genética. A eficiência de transformação foi de 2,06 a 5,96%. Dessas, apenas uma foi caracterizada por Southern blot apresentando 1 número de cópia do DNA no genoma da planta. / HLB is currently considered the main disease affecting citrus plants. Given this factor, research for cultivars resistant to this disease is needed. Genetic transformation via Agrobacterium with the use of model plants has been an alternative for checking the gene function in response to pathogens, because these model plants have as characteristic a short life cycle and high power of regeneration. Therefore, the aim of this work was to produce transgenic plants, via Agrobacterium tumefaciens, of Micro-Tom tomato (Solanum lycopersicum L.), and sweet orange, with the genes encoding the PR-8 and CDR-1 proteins isolated from Citrus sinensis. The cotyledons from in vitro germinated Micro-Tom tomato seeds were used as explants source for genetic transformation experiments with PR-8 and CDR-1 genes. These explants were subcultured until the appearance of regenerating shoots and after transgenic plants, which were acclimatized and taken to a greenhouse. The transgenic plants were confirmed by PCR and the number of gene insertions by Southern blot. The plants were grown until T1 generation was obtained. Simultaneously genetic transformation experiments were performed with epicotyl segments from \'Hamlin\' sweet orange seeds germinated in vitro with CDR-1 gene in order to obtain transgenic plants and their characterization. Simultaneously, the standard curve construction was performed by qPCR analysis for identification of Pseudomonas syringae pv. tomato. Thirteen transgenic plants of Micro-Tom tomato with PR-8 gene and three with CDR-1 gene were obtained. The transformation efficiencies were around 0,38 to 1,98%. Three transgenic plants of Micro-Tom tomato with PR-8 gene were characterized by southern blot, and the number of inserts ranged from 1 to 3. Nineteen transgenic \'Hamlin\' sweet orange plants with CDR-1 gene were obtained through genetic transformation experiments, and the transformation efficiency was 2,06 to 5,96%. One plant was characterized, by Southern blot and has one DNA copy number in the plant genome.

A leprose dos citros, principal doença viral que afeta a citricultura no Brasil, é causada pelo Citrus leprosis virus C (CiLV-C, gênero Cilevirus). CiLV-C possui um genoma bipartido de RNA de fita simples, polaridade positiva, que codifica para seis proteínas. O vírus é transmitido de planta a planta por ácaros Brevipalpus phoenicis e pode infectar mais de 40 espécies vegetais, produzindo lesões localizadas cloróticas ou necróticas ao redor do sítio de inoculação pelo ácaro. Invariavelmente, o patógeno não realiza movimento sistêmico em nenhuma de suas hospedeiras conhecidas. Para se revelar os mecanismos moleculares que determinam a atípica interação vírus/ácaro/planta, as atividades das principais vias de defesa foram avaliadas durante a infestação de A. thaliana com ácaros avirulíferos e virulíferos para o CiLV-C. A expressão de 19 genes marcadores associados às respostas de defesa do hospedeiro foi verificada mediante PCR quantitativo (RT-qPCR) em um experimento de time course (6, 12 e 24 horas após a infestação, e no momento do aparecimento dos sintomas de leprose). As análises demostraram que os genes envolvidos na via do ácido salicílico (SA) foram induzidos durante a interação com o ácaro e com o vírus. O perfil de expressão dos genes desta via durante a infestação com ácaros virulíferos foi similar ao observado com ácaros avirulíferos, porém a resposta da planta a ambos os estímulos foi mais intensa. Ademais, ambas as vias do ácido jasmônico e etileno foram ativadas durante a interação com o ácaro e reprimidas ao longo da infecção com o vírus, sugerindo uma interferência antagonística mediada pela via do SA. O mecanismo de silenciamento de RNA foi regulado de maneira diferencial em resposta à interação com ácaros avirulíferos e virulíferos. Diante da infecção viral, em tempos iniciais da infecção, as plantas responderam com a ativação de uma primeira linha de defesa mediada por AGO1, e depois alternaram para uma segunda linha de defesa mediada por AGO2. Os resultados indicam a ativação de um processo multifatorial em resposta ao CiLV-C e ao ácaro B. phoenicis em A. thaliana. / Citrus leprosis, the main viral disease affecting citrus orchards in Brazil, is caused by Citrus leprosis virus C (CiLV-C, genus Cilevirus). CiLV-C has a bipartite genome of singled stranded positive RNA, which encodes six proteins. CiLV-C is plant-to-plant transmitted by Brevipalpus phoenicis mites and can infect more than 40 plant species, invariably producing localized chlorotic or necrotic lesions around the site of feeding of the viruliferous mites. Viral long distance movement in its hosts is not accomplished. To unveil the mechanisms determining the unique characteristic of the virus/mite/plant interaction, activities of main plant defense pathways were evaluated during aviruliferous and CiLV-C viruliferous mite infestation in Arabidopsis thaliana. The expression of 19 marker genes involved in defense responses along a time course experiment (6, 12 and 24 hours after infestation, and after appearance of leprosis symptoms) was assessed by RT-qPCR. Analyses showed that genes involved in the salicylic acid (SA) pathway were up-regulated during plant interaction with mite and virus. The SA pathway expression profile observed at the infestation by viruliferous mites resembled those observed for the aviruliferous mites, but plant response to both stimuli was stronger. Both the jasmonic acid and ethylene pathways were activated during mite/plant interaction and were repressed at the course of infection with CiLV-C, suggesting an antagonistic effect mediated by the activated SA pathway. Gene silencing mechanism was differentially regulated in response to both aviruliferous and viruliferous mites. Upon viral infection, plants responded with the activation of an AGO1-mediated first defense line, in early times of infection; and then switched to an AGO2-mediated defense. Results indicate the activation of a multifactorial process in response to CiLV-C and B. phoenicis mites in A. thaliana.

Process models are always associated with uncertainty, due to either inaccurate model structure or inaccurate identification. If left unaccounted for, these uncertainties can significantly affect the model-based decision-making. This thesis addresses the problem of model-based optimization in the presence of uncertainties, especially due to model structure error. The optimal solution from standard optimization techniques is often associated with a certain degree of uncertainty and if the model-plant mismatch is very significant, this solution may have a significant bias with respect to the actual process optimum. Accordingly, in this thesis, we developed new strategies to reduce (1) the variability in the optimal solution and (2) the bias between the predicted and the true process optima. Robust optimization is a well-established methodology where the variability in optimization objective is considered explicitly in the cost function, leading to a solution that is robust to model uncertainties. However, the reported robust formulations have few limitations especially in the context of nonlinear models. The standard technique to quantify the effect of model uncertainties is based on the linearization of underlying model that may not be valid if the noise in measurements is quite high. To address this limitation, uncertainty descriptions based on the Bayes’ Theorem are implemented in this work. Since for nonlinear models the resulting Bayesian uncertainty may have a non-standard form with no analytical solution, the propagation of this uncertainty onto the optimum may become computationally challenging using conventional Monte Carlo techniques. To this end, an approach based on Polynomial Chaos expansions is developed. It is shown in a simulated case study that this approach resulted in drastic reductions in the computational time when compared to a standard Monte Carlo sampling technique. The key advantage of PC expansions is that they provide analytical expressions for statistical moments even if the uncertainty in variables is non-standard. These expansions were also used to speed up the calculation of likelihood function within the Bayesian framework. Here, a methodology based on Multi-Resolution analysis is proposed to formulate the PC based approximated model with higher accuracy over the parameter space that is most likely based on the given measurements. For the second objective, i.e. reducing the bias between the predicted and true process optima, an iterative optimization algorithm is developed which progressively corrects the model for structural error as the algorithm proceeds towards the true process optimum. The standard technique is to calibrate the model at some initial operating conditions and, then, use this model to search for an optimal solution. Since the identification and optimization objectives are solved independently, when there is a mismatch between the process and the model, the parameter estimates cannot satisfy these two objectives simultaneously. To this end, in the proposed methodology, corrections are added to the model in such a way that the updated parameter estimates reduce the conflict between the identification and optimization objectives. Unlike the standard estimation technique that minimizes only the prediction error at a given set of operating conditions, the proposed algorithm also includes the differences between the predicted and measured gradients of the optimization objective and/or constraints in the estimation. In the initial version of the algorithm, the proposed correction is based on the linearization of model outputs. Then, in the second part, the correction is extended by using a quadratic approximation of the model, which, for the given case study, resulted in much faster convergence as compared to the earlier version. Finally, the methodologies mentioned above were combined to formulate a robust iterative optimization strategy that converges to the true process optimum with minimum variability in the search path. One of the major findings of this thesis is that the robust optimal solutions based on the Bayesian parametric uncertainty are much less conservative than their counterparts based on normally distributed parameters.

Atualmente, o HLB é considerado a principal doença que acomete as plantas cítricas. Diante desse fator, pesquisas por cultivares resistentes a esta doença são necessárias. A transformação genética via Agrobacterium, juntamente com o uso de plantas modelos, tem sido uma alternativa para verificação do funcionamento dos genes em resposta a patógenos, isto porque as plantas modelos possuem como característica ciclo de vida curto e alto poder de regeneração. Assim sendo, objetivou-se com o presente trabalho, a transformação genética via Agrobacterium tumefaciens, de tomate Micro-Tom (Solanum lycopersicum L.) e de laranja doce, com os genes que codificam as proteínas PR-8 e CDR-1, isolados a partir de Citrus simensis. Os cotilédones provenientes de sementes germinadas in vitro de tomate Micro-Tom foram utilizados como fonte de explante para os experimentos de transformação genética com os genes PR-8 e CDR-1. Esses explantes foram subcultivados até o aparecimento de brotos regenerantes e posteriormente plantas transgênicas, as quais foram aclimatizadas e levadas a casa-de-vegetação. A transgenia foi confirmada por PCR e o número de inserções do gene por Southern blot. As plantas foram cultivadas até a obtenção da geração T1. Simultaneamente, foram realizados experimentos de transformação genética em segmentos de epicótilo, provenientes de sementes de laranja ‘Hamlin’ germinadas in vitro, com o gene CDR-1, a fim de se obter plantas transgênicas e sua caracterização. Paralelamente, foi realizada a construção da curva padrão pela análise de qPCR para identificação de Pseudomonas syringae pv. tomato. Foram obtidas treze plantas transgênicas de tomate Micro-Tom com o gene PR-8 e três com o gene CDR-1. As eficiências de transformação foram em torno de 0,38 a 1,98%. Três plantas de tomate Micro-Tom transgênicas com o gene PR-8 foram caracterizadas por Southern blot e o número de inserções variou de 1 a 3. Dezenove plantas transgênicas de laranja ‘Hamlin’ com o gene CDR-1 foram obtidas através dos experimentos de transformação genética. A eficiência de transformação foi de 2,06 a 5,96%. Dessas, apenas uma foi caracterizada por Southern blot apresentando 1 número de cópia do DNA no genoma da planta. / HLB is currently considered the main disease affecting citrus plants. Given this factor, research for cultivars resistant to this disease is needed. Genetic transformation via Agrobacterium with the use of model plants has been an alternative for checking the gene function in response to pathogens, because these model plants have as characteristic a short life cycle and high power of regeneration. Therefore, the aim of this work was to produce transgenic plants, via Agrobacterium tumefaciens, of Micro-Tom tomato (Solanum lycopersicum L.), and sweet orange, with the genes encoding the PR-8 and CDR-1 proteins isolated from Citrus sinensis. The cotyledons from in vitro germinated Micro-Tom tomato seeds were used as explants source for genetic transformation experiments with PR-8 and CDR-1 genes. These explants were subcultured until the appearance of regenerating shoots and after transgenic plants, which were acclimatized and taken to a greenhouse. The transgenic plants were confirmed by PCR and the number of gene insertions by Southern blot. The plants were grown until T1 generation was obtained. Simultaneously genetic transformation experiments were performed with epicotyl segments from \'Hamlin\' sweet orange seeds germinated in vitro with CDR-1 gene in order to obtain transgenic plants and their characterization. Simultaneously, the standard curve construction was performed by qPCR analysis for identification of Pseudomonas syringae pv. tomato. Thirteen transgenic plants of Micro-Tom tomato with PR-8 gene and three with CDR-1 gene were obtained. The transformation efficiencies were around 0,38 to 1,98%. Three transgenic plants of Micro-Tom tomato with PR-8 gene were characterized by southern blot, and the number of inserts ranged from 1 to 3. Nineteen transgenic \'Hamlin\' sweet orange plants with CDR-1 gene were obtained through genetic transformation experiments, and the transformation efficiency was 2,06 to 5,96%. One plant was characterized, by Southern blot and has one DNA copy number in the plant genome.

A leprose dos citros, principal doença viral que afeta a citricultura no Brasil, é causada pelo Citrus leprosis virus C (CiLV-C, gênero Cilevirus). CiLV-C possui um genoma bipartido de RNA de fita simples, polaridade positiva, que codifica para seis proteínas. O vírus é transmitido de planta a planta por ácaros Brevipalpus phoenicis e pode infectar mais de 40 espécies vegetais, produzindo lesões localizadas cloróticas ou necróticas ao redor do sítio de inoculação pelo ácaro. Invariavelmente, o patógeno não realiza movimento sistêmico em nenhuma de suas hospedeiras conhecidas. Para se revelar os mecanismos moleculares que determinam a atípica interação vírus/ácaro/planta, as atividades das principais vias de defesa foram avaliadas durante a infestação de A. thaliana com ácaros avirulíferos e virulíferos para o CiLV-C. A expressão de 19 genes marcadores associados às respostas de defesa do hospedeiro foi verificada mediante PCR quantitativo (RT-qPCR) em um experimento de time course (6, 12 e 24 horas após a infestação, e no momento do aparecimento dos sintomas de leprose). As análises demostraram que os genes envolvidos na via do ácido salicílico (SA) foram induzidos durante a interação com o ácaro e com o vírus. O perfil de expressão dos genes desta via durante a infestação com ácaros virulíferos foi similar ao observado com ácaros avirulíferos, porém a resposta da planta a ambos os estímulos foi mais intensa. Ademais, ambas as vias do ácido jasmônico e etileno foram ativadas durante a interação com o ácaro e reprimidas ao longo da infecção com o vírus, sugerindo uma interferência antagonística mediada pela via do SA. O mecanismo de silenciamento de RNA foi regulado de maneira diferencial em resposta à interação com ácaros avirulíferos e virulíferos. Diante da infecção viral, em tempos iniciais da infecção, as plantas responderam com a ativação de uma primeira linha de defesa mediada por AGO1, e depois alternaram para uma segunda linha de defesa mediada por AGO2. Os resultados indicam a ativação de um processo multifatorial em resposta ao CiLV-C e ao ácaro B. phoenicis em A. thaliana. / Citrus leprosis, the main viral disease affecting citrus orchards in Brazil, is caused by Citrus leprosis virus C (CiLV-C, genus Cilevirus). CiLV-C has a bipartite genome of singled stranded positive RNA, which encodes six proteins. CiLV-C is plant-to-plant transmitted by Brevipalpus phoenicis mites and can infect more than 40 plant species, invariably producing localized chlorotic or necrotic lesions around the site of feeding of the viruliferous mites. Viral long distance movement in its hosts is not accomplished. To unveil the mechanisms determining the unique characteristic of the virus/mite/plant interaction, activities of main plant defense pathways were evaluated during aviruliferous and CiLV-C viruliferous mite infestation in Arabidopsis thaliana. The expression of 19 marker genes involved in defense responses along a time course experiment (6, 12 and 24 hours after infestation, and after appearance of leprosis symptoms) was assessed by RT-qPCR. Analyses showed that genes involved in the salicylic acid (SA) pathway were up-regulated during plant interaction with mite and virus. The SA pathway expression profile observed at the infestation by viruliferous mites resembled those observed for the aviruliferous mites, but plant response to both stimuli was stronger. Both the jasmonic acid and ethylene pathways were activated during mite/plant interaction and were repressed at the course of infection with CiLV-C, suggesting an antagonistic effect mediated by the activated SA pathway. Gene silencing mechanism was differentially regulated in response to both aviruliferous and viruliferous mites. Upon viral infection, plants responded with the activation of an AGO1-mediated first defense line, in early times of infection; and then switched to an AGO2-mediated defense. Results indicate the activation of a multifactorial process in response to CiLV-C and B. phoenicis mites in A. thaliana.

Run-of-mine ore milling circuits are generally difficult to control owing to the presence of strong external disturbances, poor process models and the unavailability of important process variable measurements. These shortcomings are common for processes in the mineral-processing industry. For processes that fall into this class, the peripheral control tools in the control loop are considered to be as important as the controller itself. This work addresses the implementation of peripheral control tools on a run-of-mine ore milling circuit to help overcome the deteriorated control performance resulting from the aforementioned shortcomings. The effects of strong external disturbances are suppressed through the application of a disturbance observer. A fractional order disturbance observer is also implemented and a novel Bode ideal cutoff disturbance observer is introduced. The issue of poor process models is addressed through the detection of significant mismatch between the actual plant and the available model from process data. A closed-form expression is given for the case where the controller has a transfer function. If the controller does not have a transfer function, a partial correlation analysis is used to detect the transfer function elements in the model transfer function matrix that contain significant mismatch. The mill states and important mill parameters are estimated with the use of particle filters. Simultaneous state and parameter estimation is compared with a novel dual particle filtering scheme. A sensitivity analysis shows the class of systems for which dual estimation would provide superiorestimation accuracy over simultaneous estimation. The implemented peripheral control tools show promise for current milling circuits where proportional-integral-derivative (PID) control is prevalent, and also for advanced control strategies, such as model predictive control, which are expected to become more common in the future. AFRIKAANS : Maalkringe wat onbehandelde erts maal is oor die algemeen moeilik om te beheer as gevolg van die teenwoordigheid van sterk eksterne steurings, onakkurate aanlegmodelle en metings van belangrike prosesveranderlikes wat ontbreek. Hierdie probleme is algemeen vir aanlegte in die mineraalprosesseringsbedryf. Vir aanlegte in hierdie klas word die randbeheerinstrumente as net so belangrik as die beheerder beskou. Hierdie verhandeling beskryf die implementering van randbeheerinstrumente vir ’n maalkring wat onbehandelde erts maal, om die verswakte beheerverrigting teen te werk wat veroorsaak word deur bogenoemde probleme. Die impak van sterk eksterne steurings word teengewerk deur die implementering van ’n steuringsafskatter. ’n Breuk-orde-steuringsafskatter is ook geïmplementeer en ’n nuwe Bode ideale afsnysteuringsafskatter word voorgestel. Die kwessie van onakkurate aanlegmodelle word hanteer deur van die aanlegdata af vas te stel of daar ’n verskil is tussen die aanleg en die beskikbare model van die aanleg. ’n Uitdrukking word gegee vir hierdie verskil vir die geval waar die beheerder met ’n oordragsfunksie voorgestel kan word. Indien die beheerder nie ’n oordragsfunksie het nie, word van ‘n parsiële korrelasie-analise gebruik gemaak om die element, of elemente, in die aanleg se oordragsfunksiematriks te identifiseer wat van die werklike aanleg verskil. Die toestande en belangrike parameters in die meul word beraam deur van partikel-filters gebruikte maak. Gelyktydige toestand- en parameter-beraming word vergelyk met ’n nuwe dubbel-partikelfilter skema. ’n Sensitiwiteitsanalise wys die klas van stelsels waarvoor dubbel-afskatting meer akkurate waardes sal gee as gelyktydige afskatting. Die voorgestelde randbeheerinstrumente is toepaslik vir huidige maalkringe waar PID-beheer algemeen is, asook vir gevorderde beheerstrategieë, soos model-voorspellende beheer, wat na verwagting in die toekoms meer algemeen sal word. Copyright / Dissertation (MEng)--University of Pretoria, 2012. / Electrical, Electronic and Computer Engineering / unrestricted

Proportional, integral and derivative (PID) controller tuning guidelines in process industry have been in place for over six decades. Nevertheless despite their long design history PID tuning has remained an ‘art’ and no single comprehensive solution yet exists. In this study various considerations, with new and different perspectives, have been taken into account in PID tuning design. This study explores the issue of PID tuning from a practical point of view with particular focus on robust design in the presence of typical problems in process industry: process changes, valve stiction effects and unmeasured disturbances. The IMC tuning rule is recommended for setpoint tracking, while in the case of regulation, a newly proposed tuning rule, based on a combination of IMC and Ziegler-Nichols method, is demonstrated to give satisfactory results. The results were evaluated by simulation and were also validated on a computer-interfaced pilot scale continuous stirred tank heater (CSTH) process. / Chemical Engineering

No description available.