Recent experiments are bringing to the fore more and more information about the effects of different treatments on the gene expression of different genes. The results obtained from these experiments show that some definite trends are observed in different genes in the Human Embryonic Kidney and Human Colon Adenocarcinoma Grade II cell lines. The difference in the gene expressions of the two cell lines motivates the problem in this thesis. The thesis provided intervention methods to make the colon cancer cell line genes behave more like their Human Embryonic Kidney cell line counterparts. Two methods of intervention were introduced. The first method was the simpler on-off control intervention while the second method used a more advanced proportional integral control to meet the goal. A comparison of these two intervention methods showed the clear implementational advantages of proportional integral control over on-off control.

This thesis deals with chemical plants constituted by parallel batch-continuous production lines with shared resources. For such plants, it is highly desirable to have optimal operation schedules which determine the starting times of the various batch processes and the flow rates of the continuous processes in order to maximize the average plant productivity and to have a continuous production without interruptions. This optimization problem is constrained by the limitation of the resources that are shared by the reactors and by the capacities of the various devices that constitute the plant. Such plants are "hybrid" by nature because they combine both continuous-time dynamics and discrete-event dynamics. The formalism of "Hybrid Automata" is there fore well suited for the design of plant models. The first contribution of this thesis is the development of a hybrid automaton model of the chemical plant in the Matlab-Simulink-Stateflow environment and its use for the design of an optimal periodic schedule that maximises the plant productivity. Using a sensitivity analysis and the concept of Poincaré; map, it is shown that the optimal schedule is a stable limit cycle of the hybrid system that attracts the system trajectories starting in a wide set of initial conditions. The optimal periodic schedule is valid under the assumption that the hybrid model is an exact description of the plant. Under perturbations on the plant parameters, it is shown that two types of problems may arise. The first problem is a drift of the hybrid system trajectory which can either lead to a convergence to a new stable sub-optimal schedule or to a resource conflict. The second problem is a risk of overflow or underflow of the output buffer tank. The second contribution of the thesis is the analysis of feedback control strategies to avoid these problems. For the first problem, a control policy based on a model predictive control (MPC) approach is proposed to avoid resource conflicts. The feedback control is run on - line with the hybrid Simulink-Stateflow simulator used as an internal model. For the solution of the second problem, a classical PI control is used. The goal is not only to avoid over- or under-filling of the tank but also to reduce the amplitude of outflow rate variations as much as possible. A methodological analysis for the PI controller tuning is presented in order to achieve an acceptable trade-off between these conflicting objectives.

Made available in DSpace on 2014-07-29T15:08:24Z (GMT). No. of bitstreams: 1 Dissertacao Nelio Neves.pdf: 3219323 bytes, checksum: 942eb8a565f853723f37d1f40fe87298 (MD5) Previous issue date: 2010-03-26 / This text reports the effort to present a proposal of a power generation system based on cage rotor Induction Electrical Machine associated to a sinusoidally-switched PWM (Pulse Width Modulation) frequency converter responsible for maintaining constant 60 Hz frequency at the generator leads. DC side at the PWM converter is nonsynchronously connected to a single-phase utility line by means of a full-bridge current-fed thyristor inverter, employing a step-down DC-DC converter in order to turn the grid injected current into a sinusoidal waveform. The proposed system allows for the operation as cogenerator in sites fed by single-phase utility net where there is availability of energetic resources. The DC capacitor voltage (Vdc) is controlled through the DC side energy balance adjusting the amplitude of the active current sent to the utility grid. The control strategy employed was the analogic proportional-integral (PI) error compensation. The system is also able to act as reactive power compensator to the AC loads as the Cdc capacitor represents a voltage source to the inverter and the three-phase diode bridge allows for bidirectional power flow between AC and DC sides. Simulation and experimental results has corroborated system viability to provide three-phase balanced regulated voltages complying with ANEEL 505/2001 Resolution and with IEEE Std 519-1992. / Este trabalho apresenta a proposta de um sistema para geração de energia elétrica baseado na Máquina de Indução Trifásica (MIT) com rotor tipo gaiola de esquilo associada a um conversor de freqüência chaveado no modo PWM (modulação por largura de pulsos na sigla em inglês) senoidal. O lado CC do conversor de frequência é conectado assincronamente à rede monofásica da concessionária através de um inversor monofásico em ponte completa a tiristores, alimentado em corrente, e de um conversor CC-CC abaixador de tensão, utilizado para modular senoidalmente a corrente injetada na rede via inversor. Este sistema permite a operação como co-gerador em localidades alimentadas por linhas monofásicas e com disponibilidade de recursos energéticos. O conversor de freqüência é responsável por manter a freqüência fundamental nos terminais do gerador de indução fixa em 60 Hz. A tensão no capacitor Ccc (Vcc) é controlada através da manutenção do balanço energético no lado CC do conversor PWM, ajustando a amplitude da corrente ativa injetada na rede monofásica em um valor adequado. A estratégia empregada para implementação do controle foi a compensação analógica tipo proporcional-integral (PI) do erro de Vcc. O sistema é ainda capaz de atuar como compensador de potência reativa para as cargas CA, já que o capacitor Ccc representa uma fonte de tensão contínua para o inversor e a ponte trifásica a diodos permite o fluxo bidiredional de energia entre os lados CA e CC do sistema. Os resultados de simulação e experimentais sustentam a viabilidade do sistema para prover tensões trifásicas equilibradas e reguladas, satisfazendo os requisitos da resolução 505/2001 da ANEEL e da norma IEEE Std 519-1992 do IEEE/ANSI.