Dissertations / Theses on the topic 'Process control'

The cheese making process at Anchor Products Hautapu was having difficulty reaching the now outdated New Zealand Dairy Board uniformity targets. Even though there is no longer a direct financial benefit in reaching these targets consistently, there is the benefit of being able to show the customer that the product which they are receiving is as consistent as possible. This project was carried out by systematically investigating each section of the cheese making process, looking for variations that were likely to affect the final product. Where variations were found methods for eliminating them or minimising their effect on the final product were developed. The largest source of variation was found to be caused by fluctuations in the curd depths on the belts of the Alf-O-Matic cheddaring machine. Overlapping the ends of consecutive cheese making tanks as well as the re-calculations of the pump out flow rates have been proposed to remedy this problem. Where the curd is drawn off from the end of the Alf-O-Matic cheddaring machine was also found to be causing variation in the product due to particle stratification affecting the salt levels of blocks that were being produced. Recommendations for methods to reduce the level of stratification have been suggested including using a capacitance probe to control the curd level. Further variations were occurring within the cheese making tanks with cutting and stirring speeds differing from tank to tank. The tanks were also being flushed with cold water causing moisture spikes in the product. Both of these problems have been eliminated by changes to the PLC program. Small improvements have been seen in the process with the changes that have already been carried out. Large improvements are expected if the rest of the recommendations are implemented. The largest improvements should be seen with the realisation of an overlapped pump out system.

This thesis examines the existing theories and applications of Multivariate Statistical Process Control, outlines areas of difficulty and proposes a new technique of multivariate process control chart with input-output relationship for optimal process control. The process control techniques developed up to the present time focused on the fast detection of out-of-control signals, and achieved considerable success in that respect. The techniques reported on multivariate process control thus far include extensions of univariate process control charts to their multivariate counterparts, ranging from classical Shewharts charts to modern Cumulative Sum Process Control charts. Alternative approaches in this area include Principal Component Approach, Partial Regression approach, Baysian modelling and sequential tests on detection of change points. Although each method has its own limitation, these new developments have significantly contributed to the achievement of a constant high quality of products and services. The techniques of process control are yet incomplete. They require continuous attention, as production and service technologies are being continuously developed.In particular, the level of automation, re-engineering of production processes and ever demanding economic optimality of technology demand the re-engineering of statistical process control. The CFM chart developed in this thesis would open the door to this area of science and lays a critical foundation for future research
Doctor of Philosophy (PhD)

This thesis examines the existing theories and applications of Multivariate Statistical Process Control, outlines areas of difficulty and proposes a new technique of multivariate process control chart with input-output relationship for optimal process control. The process control techniques developed up to the present time focused on the fast detection of out-of-control signals, and achieved considerable success in that respect. The techniques reported on multivariate process control thus far include extensions of univariate process control charts to their multivariate counterparts, ranging from classical Shewharts charts to modern Cumulative Sum Process Control charts. Alternative approaches in this area include Principal Component Approach, Partial Regression approach, Baysian modelling and sequential tests on detection of change points. Although each method has its own limitation, these new developments have significantly contributed to the achievement of a constant high quality of products and services. The techniques of process control are yet incomplete. They require continuous attention, as production and service technologies are being continuously developed.In particular, the level of automation, re-engineering of production processes and ever demanding economic optimality of technology demand the re-engineering of statistical process control. The CFM chart developed in this thesis would open the door to this area of science and lays a critical foundation for future research

Thesis (PhD (Philosophy))-- University of Western Sydney, Nepean, 1998.
"Thesis submitted for the fulfilment of the requirement of Doctor of Philosophy in quantitative methods, School of Quantitative Methods and Business Operations, Faculty of Commerce, University of Western Sydney, Nepean" Bibliography : p 233-257.

The master work topic is dealt with process control system Control Web 7. After the introductory preface is followed by the specification and description of controlled process (the specification). The following is verbally with the assistance of the flowchart describes the concept of the whole system under manufacture. Then there is outlined how to proceed with an application programming and is described also Control Web 7. The last part of the master work is devoted to final inspection using the program module VisionLab compared with competing vision systems, which is an addition to the family of Control Web.

In this thesis process control concepts were used to develop software that could be adapted to a real world situation. The software was used to control a simple temperature regulating experiment. This experiment was used to demonstrate the use of OPTOMUX analog and digital input/output devices in controlling a process. The goal of this experiment was to use the input/output devices in controlling the temperature of the box within specified tolerances for a designated period of time. To accomplish optimal use of equipment and optimal control, a mathematical model was derived to predict the behavior of the process under control. The pattern observed while the temperature was increasing toward room temperature closely resembled an exponential function. For temperatures above room temperatures the curve then approximated a square root function. The pattern followed when decreasing the temperature-was exponential throughout. The time required to collect all the significant data in the case of increasing the temperature was two hours. In the case of decreasing temperature, one hour. Beyond these time limits the temperature remained essentially constant. The maximum temperature value that could be reached was six degrees above room temperature and the minimum two degrees below room temperature.

Orientadores: Flávio Vasconcelos da Silva, Rubens Gedraite
Dissertação (mestrado) - Universidade Estaual de Campinas, Faculdade de Engenharia Química
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Resumo: A presença de resíduos em superfícies mal higienizadas pode aumentar a incidência de microrganismos e ocasionar problemas operacionais nos equipamentos de processo. A identificação da dinâmica do processo pode contribuir para a melhoria da sua eficiência, racionalizando o uso de água e energia empregada nas operações de enxágue. Atualmente, a maioria dos processos de limpeza CIP é conduzida com base em procedimentos padronizados considerando a experiência dos operadores de processo no que tange ao tempo de funcionamento do ciclo. Este trabalho aborda, em um primeiro momento, a implantação da instrumentação e do sistema de controle necessários para monitorar e controlar o processo e, na sequência, o levantamento experimental do comportamento do sistema a estímulos na vazão e/ou temperatura de operação do processo. Para tal foi utilizado um trocador de calor instalado em planta piloto com o objetivo de relacionar, ao longo do tempo, a variação da alcalinidade (pH) da água empregada para remoção do detergente alcalino utilizado no processo de limpeza com a temperatura e vazão da mesma. Neste trabalho a planta utilizada possui dimensões de uma planta semi-industrial típica; tal característica possibilita que se considerem as dinâmicas e fenômenos encontrados em plantas reais, obtendo-se resultados de grande interesse prático. Os equipamentos utilizados (sensores, interfaces e atuadores) são padrão de mercado, adequadamente combinados e instalados de maneira a permitir o estudo de vários aspectos relacionados às etapas de um processo CIP. Testes foram realizados na planta partindo dos parâmetros de sintonia calculados pelo método ITAE por Rovira para o controle de vazão do fluido de processo. Os valores finais dos parâmetros PID que apresentaram o melhor resultado e foram utilizados na planta foram: Kp= 2,68 e Ti= 0,101 s. Devido à diferença na dinâmica para aumento e redução da temperatura para o controle de temperatura do fluido de processo, partiu-se dos parâmetros de sintonia calculados pelo Método CHR sem sobre valor. Os valores finais dos parâmetros PID que apresentaram o melhor resultado nos testes e foram utilizados na planta foram: para o aumento da temperatura Kp = 6,394, Ti = 3,640 s e Td=0,621 s, e para a diminuição da temperatura, foi utilizado o controlador proporcional com o parâmetro Kp = 0,08. A cinética da remoção foi avaliada a partir da variação do pH medido. Foram identificadas as dinâmicas da planta para diferentes condições operacionais que mostram que os parâmetros dinâmicos do sistema são fortemente influenciados pelas vazões e pouco afetados pelas temperaturas utilizadas, com maior contribuição para valores mais elevados de vazão (16 L.min-1), onde há menor consumo de água. Apesar de a identificação aproximada apresentar um modelo (com erro) que representa a resposta do processo, motivou-se o uso de uma metodologia de identificação mais refinada com o objetivo de comparação. Esta foi obtida através de modelos baseados no sistema de Inferência Fuzzy Neuro-Adaptativo (ANFIS) através do aplicativo Simulink/MATLAB'MARCA REGISTRADA'. Os resultados obtidos com os modelos foram validados por comparação com os dados experimentais. Para este processo duas entradas (a saída atrasada em uma amostragem - pH [k-1] - e a vazão atual - F[k]) e uma saída (o pH atual - pH[k]) para o treinamento da rede, mostraram ser mais adequadas para modelar a resposta da dinâmica do pH na etapa de enxague estudada. O erro médio foi de 0,011 quando comparados os dados experimentais coletados com o modelo obtido (tanto com o uso do algoritmo Grid partition quanto com o algoritmo Subtractive Clustering e com o uso de 3 ou 5 funções de pertinência do tipo triangular)
Abstract: The presence of residues in poorly cleaned surfaces may increase the micro-organisms incidence and cause operational problems in process equipments. The process dynamics identification can contribute to improve efficiency, rationalizing the energy and water used in rinsing operations. Nowadays, most of CIP cleaning process is conducted based on standard procedures considering the process operators' experience regarding the operating time cycle. This paper discusses, at first, the instrumentation and control system implementation required to monitor and control the process and, after that, the experimental tests to analyze the system behavior to stimuli in flow and/or process operating temperature. For that it was used a heat exchanger installed in a pilot plant in order to relate, over time, the water alkalinity (pH) variation used to remove alkaline detergent used in the cleaning process with the temperature and flow rate of the same. The plant used in this study has the typical dimensions of a semi-industrial plant; this characteristic makes it possible to consider the dynamic and phenomena found in real plants, obtaining results of great practical interest. It was used industry standard equipments (sensors, actuators and interfaces) properly combined and installed so as to allow the study of various aspects related to the CIP process stages. Tests were done in the plant starting with the tuning parameters calculated by the ITAE by Rovira method to control the process fluid flow. The final PID parameters values that presented the best results and were used in the plant were: Kp = 2.68 and Ti = 0.101 s. Due to the difference in dynamics for increasing and decreasing temperature to control the process fluid temperature, It was started from the tuning parameters calculated by the CHR method without over value. The final PID parameter values that had the best results in the plant and were used were: for the temperature increase Kp = 6,394, Ti = 3,640 s and Td=0,621 s, and for decreasing temperature it was used a proportional controller with the parameter Kp = 0.08. The kinetics removal was evaluated starting from the measured pH variation. The plant dynamics were identified for different operating conditions which shows that the system's dynamic parameters are strongly influenced by the flow and little affected by the temperatures used, with a greater contribution for higher flow levels (16 L.min-1), where there is less water consumption. Although the approximate identification provide a suitable model (with error) that represents the process response, there was a motivation for the use of a more refined identification methodology with the objective of comparing. It was obtained by Adaptive Neuro-Fuzzy Inference System (ANFIS) model-based via Simulink/MATLAB'TRADE MARK' software. The results obtained with those models were validated by comparison with the experimental data. For this process two inputs (the output delayed by one sample - pH [k-1] - and the current flow - F[k]) and one output (the current pH - pH [k]) to the network training, revealed to be more appropriate to model the pH dynamics response in the rinse step studied. The average error was 0,011 when comparing the experimental collected data with the obtained model (either using the Grid Partition algorithm and the Subtractive Clustering algorithm and using 3 or 5 triangular membership functions)
Mestrado
Sistemas de Processos Quimicos e Informatica
Mestre em Engenharia Química

The research site has been the Södra Cell Tofte pulp mill. The main focus in this thesis is how to learn about process control. The need for research on this theme is given implicitly in the foundation and construction of the INPRO programme. Norwegian engineering education is discipline oriented, and the INPRO programme aimed at integrating the three disciplines engineering cybernetics, chemical engineering, and organisation and work life science in a single PhD programme. One goal was to produce knowledge of modern production in chemical process plants based on socio-technical thinking.

In the introduction I outline how my research questions have been developed and the need for doing research in the field of improving process understanding in a continuous process plant.

This thesis provides answer to the three questions:

1. What are the learning systems for workers in a process plant?

2. What is the implication for learning of different socio-technical structures?

3. How can learning be further improved for workers in the process industry?

In order to answer these questions and to provide a background for why these questions are important to Tofte, I describe and analyse the case plant Södra Cell Tofte. I find it necessary to make this part rather extensive in order for the reader to understand the context under which Tofte has been developing its learning arenas or learning systems. I use a sociotechnical framework in doing this. I want to introduce and use this framework as I regard it as useful for one of my purposes with this work: Assisting the production unit at Tofte to improve learning. I go through technological improvements that have been carried out from 1980 onwards, and one major organisational change that has taken place. The downsizing and reorganisation that took place in 1992 is of importance as well as the organisational development effort named “Employeeship” that took place in 1996. I had a leave from the INPRO project for almost a year following and evaluating this particular project. The situation at Tofte in 1994 was lack of good learning systems, and after a major reorganisation in 1992 the organisation defined a need for better responsibility distribution and co-operation.

Chapters 3 and 4 present and discuss theories in order to give a broader background for the research issues in this thesis. In Chapter three I discuss features and characteristics of a continuous process plant as these have consequences on how knowledge and skills can be developed and why process understanding is a necessity. I present socio-technical system thinking (STS) as one way of regarding organisation and management of a process plant, and I further discuss why I find this approach appropriate for providing learning primarily at the shop floor level as an integrated part of daily production.

In Chapter four I argue that knowledge and skills in production are becoming increasingly important in highly automated remotely controlled process plants and develop a theory of “process understanding”. Process understanding is defined as the ability to predict what is going to happen. In order to predict what is going to happen with a system one firstly need to define the system boundaries. This system can then be regarded as a mental model. One must know and analyse input variables (know where and how to get relevant process information), and by this anticipate, like in a mental simulation, what will happen with the parameters within a defined time period. Different possible options may be mentally tested including what will happen if no corrective actions are taken. An ability to predict what is going to happen with the product, to process equipment or any other process variable, has to be developed and refined in order to operate a process plant optimally. Theories state that a variety of knowledge and skills are required and that some skills can be acquired only through years of experience. The “knowing why” within a process plant also has to be strengthen in order to develop a better process understanding, but as an addition to the experience based “knowing how”.

Models of learning regarding the demands given by the production systems in order to develop such process understanding are presented and discussed. These are conventional methods, experiential (problem based) learning, and collective learning. The experiential learning model is discussed and what may inhibit learning from experiences to take place in a plant. I have defined the concept “learning arena” and regarded each shift in a control room as a main learning arena since this is the place where theory meets practice. It is further discussed that practice will differ between shifts within same control room due to different mental models of the process. In various learning arenas, different communities-ofpractice must be joined in order to make more shared mental models with the intention to align different practices.

In Chapter five the research methods used to explore the research questions, and thus to bring forth theories about gaining better process control, are reviewed. I have been inspired by action research methods in order to answer my research questions and to contribute in a necessary change process where development and use of learning arenas have been central. I have been more or less active in these arenas and played back experiences and theories in order to further develop the arenas. Besides participations in learning arenas, methods have been interviews, observations, and written documentations.

Chapter six is the case description of two different kinds of learning systems at Tofte: Operator Training (OT) - Operator based development and execution of education/ training and Operations Workshop (OW) - Problem based learning aiming at better production practice. I have provided background for the two cases as an answer to the educational challenges Tofte had in 1996 and not least to differences in operational practice between shifts. I describe background, characteristics, and development from what I term different learning arenas where the learning about process control will take place. I have also discussed in what ways these two learning systems can be regarded as learning arenas and briefly the kind of learning that can take place in each arena. In two Operations workshops I provide more details in order to show some strengths of the method.

In Chapter seven I provide answers to the three research questions outlined in the introduction and further refined in Chapter 4.5. I analyse how different learning types such as individual, experiential, and collective are covered within different learning arenas and how OT and OW meet the requirements for good learning systems in continuous process plants. Further I analyse how tasks regarding education and training are better distributed in a shift and daytime organisation with the two learning systems, and further how learning is integrated with working and thus process operators’ knowledge and skills are better utilised. When I analyse the implication of learning of two different socio-technical structures, I also regard how managers are better enabled to become facilitators for learning. The two arenas have been well established at Tofte, but to a varying degree in the different departments. When regarding Operator training it is still too early to conclude on its impact on results in the pulp mill. However, two Operations workshops have made positive contributions and demonstrated the potential of the method. The strengths of the methods are the collective learning that place in cogenerated learning arenas. In Operator training this strengthens the master-apprentice method, and in Operations workshops it gives a shared understanding and direction for further tasks in process control. Finally, based on the analysis of the first two questions I discuss how learning for workers can be further improved.

In Chapter eighth I conclude on my theoretical contribution and arguments for further research in the actual fields. Finally, based on my findings I will recommend organisational choices on future actions. STS provides frames and directions for learning to take place within groups along the production line. It is however not the scope of the STS paradigm to provide theories of what constitutes knowledge in operations of a plant. And the STS theories are not developed in order to cover more specifically models for how learning within and across semi-autonomous units and organisational levels may take place. Thus the main contribution of this thesis is learning theories based on two different kinds of learning models as means to develop process understanding.

Most Statistical Process Control (SPC) research has focused on the development of charting techniques for process monitoring. Unfortunately, little attention has been paid to the importance of bringing the process in control automatically via these charting techniques. This thesis shows that by drawing upon concepts from Automatic Process Control (APC), it is possible to devise schemes whereby the process is monitored and automatically controlled via SPC procedures. It is shown that Partial Correlation Analysis (PCorrA) or Principal Component Analysis (PCA) can be used to determine the variables that have to be monitored and manipulated as well as the corresponding control laws. We call this proposed procedure Active SPC and the capabilities of various strategies that arise are demonstrated by application to a simulated reaction process. Reactor product concentration was controlled using different manipulated input configurations e.g. manipulating all input variables, manipulating only two input variables, and manipulating only a single input variable. The last two manipulating schemes consider the cases when all input variables can be measured on-line but not all can be manipulated on-line. Different types of control charts are also tested with the new Active SPC method e.g. Shewhart chart with action limits; Shewhart chart with action and warning limits for individual observations, and lastly the Exponentially Weighted Moving Average control chart. The effects of calculating control limits on-line to accommodate possible changes in process characteristics were also studied. The results indicate that the use of the Exponentially Weighted Moving Average control chart, with limits calculated using Partial Correlations, showed the best promise for further development. It is also shown that this particular combination could provide better performance than the common Proportional Integral (PI) controller when manipulations incur costs.

One problem of special interest both in industry and the engineering community is that of using the enormous amounts of data routinely generated and recorded in e client process monitoring and control strategies. In statistical terms this is related to identifying those variables which exhibit unwanted or unusual process variability so that remedial action can be taken. To this end, a common approach in the literature is to reduce the problem dimensionality by using latent variable models. Customarily, the latent variables are a function of all of the original variables and monitoring is carried out in the reduced space. Within this context, this thesis explores the development of models in which the latent factors are a function of a subset, only, of the original observations. By doing that, the advantages of monitoring in a reduced subspace are retained but there there are also additional gains in model interpretability. The idea arises from the sparse representation of the mapping matrix between latent and original variables in a linear factor analysis (FA) model. An extension of principal component analysis (PCA) to monitor nonlinear systems is proposed by using a a Gaussian Process Latent Variable model [Lawrence, 2005], GPLVM, as a starting point. Its application in a process control problem is also introduced. Using a Gaussian process, GP, as the backbone, we define a Gaussian Process Functional Factor Analysis model which maps subsets of the latent variables to the observed data-space; a study of the model asymptotic properties is given. Several parameter inference methods as well as a model selection procedure via penalty functions are also proposed. There are several scienti c disciplines involved in the problem at hand. Chemical engineers refer to it as a sub- eld of Process Control known as Multivariate Statistical Process Control. It is also an area of tremendous success in process Chemometrics where it has grown very rapidly over the last two decades. In Statistics, it touches the topics of latent variable models and variable selection methods. And within the Machine Learning community is classified as an Unsupervised Learning problem.

The master´s thesis deals with the problem of statistical process control. The theoretical part describes the basic quality tools and new quality tools, as a tool for collecting, recording, classifying, and analyzing data. The knowledge gained from the theoretical part are used to describe processes in the company Heat Transfer Systems s.r.o., analyze sticking points, control plans updating and to statistical process control in the organization.

PCS are used to control parts of the critical infrastructure of society, such as electric utilities, petroleum , water, waste, chemicals and pharmaceuticals amongst others. If the PCS become victims of cyber attacks, this can have severe consequences. The consequences may involve health and safety of human lives as well as having a huge impact on national and global economy. Since the merging of COTS and PCS, the previously isolated PCS now face new types of threats due to well-known flaws in COTS, as well as being connected to the Internet. Therefore the focus on securing PCS and ICS in general should get increased attention. In this thesis the laboratory system used was a scaled down PCS that could be tested on without any serious consequences. The laboratory system was delivered by Kongsberg Maritime. The OS is the first unit an attacker from the outside has contact with and it is used for controlling the other components of the system, therefore the OS is the main source of attention in this thesis. A scan was made on the OS to map the vulnerabilities of the OS. The scan was used as a basis for the attacks. Attacks were divided into attacks from the outside (Internet) and attacks from the inside. Under the circumstances of the testing on the laboratory PCS, many of the attacks tried were successful. A shell was planted in the OS, so an attacker could control it remotely, DoS attack flooded the OS and forced it to halt for a few seconds, VNC password was found enabling remote view and control of the OS, replay of packets was successful on the inside of the system making a man in the middle scenario possible. Despite the fact that the laboratory system may not have all the security mechanisms implemented, as the PCS systems in the industry does, the fact that the attacks on the laboratory system are possible may seem a bit disturbing. To prevent from the types of attacks described in this thesis steps has to be taken. Some of the prevention steps can be to regularly patch the system, use firewall filtering, monitor nodes in case of DoS, IDS monitoring and guidelines on system use.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1991.
Includes bibliographical references (leaves 115-118).
by Ármann Ingólfsson.
M.S.

Com o aumento da produção mundial em proporções cada vez maiores, os processos industriais têm se tornando um desafio pela complexidade do seu gerenciamento. A identificação rápida e precisa de não conformidades é cada vez mais necessária e mais difícil de ser realizada. Este estudo propõe a integração do Controle de Engenharia com o Controle Estatístico de Processo, no monitoramento e controle de processos industriais, almejando a percepção mais rápida de anormalidades, visando à redução de problemas de especificação de produtos. Uma forma de autoajuste do controlador Proporcional-Integral e Derivativo (PID) é proposta, aumentando a robustez do sistema, empregando-se técnicas comumente utilizadas nos processos. O modelo matemático do processo, equacionando as relações das variáveis envolvidas, é estabelecido para determinação e especificação do controlador e de forma conjunta as cartas de controle são configuradas. O controlador projetado para a situação normal de operação atua no sentido de manter as variáveis de saída (controladas) dentro de especificações através do conhecimento de sua relação com as de entrada e de processo. As cartas de controle baseadas em modelos, monitorando os resíduos provenientes de ajustes de modelos ARIMA, acompanham as variações do processo, evitando variabilidade excessiva e possibilitando a detecção de comportamentos anormais, inclusive monitorando o desempenho do próprio controlador. Com a sinalização das cartas de controle, é realizada uma interferência na equação de ajuste do controlador. Empregando-se a simulação numérica, analisam-se os comportamentos do controlador e este, combinado com as cartas de controle. Falhas inseridas propositalmente, em cada variável controlada, foram devidamente sinalizadas. Estas sinalizações ocorreram mesmo em situações em que as variáveis estiveram mantidas dentro da especificação pelo controlador. Para o sistema de autoajuste, o aumento dos ganhos de contribuição das cartas de controle proporcionou maior acurácia das variáveis controladas (monitoradas). A integração proposta apresentou melhores resultados, quanto à manutenção das variáveis de saída próximas aos seus alvos, quando comparada com o controlador operando isoladamente.
With the increase of world production at bigger and bigger proportions, the industrial processes have become a challenge by the complexity of their management. The fast and precise identification of non-conformities is increasingly necessary and more difficult to be performed, preferably even before problems with product specification or waste can be considered. This study proposes the integration of Engineering Process Control with the Statistical Process Control, in monitoring and controlling of industrial processes, aiming the quicker perception of abnormalities, looking for the reduction of products specification problems. A form of self-adjustment of the Proportional-Integral and Derivative Controller (PID) is proposed, increasing the system robustness applying techniques commonly used in the processes. The mathematical model of the process, equating the relationship of the variables involved, is established to the determination and specification of the controller, and the control charts are configure in an integrated way. The controller projected to the normal operation situation, acts in the sense of keeping the exit variables (controlled) within the specifications through the knowledge of its relationship with that of the entrance and that of the process. The control charts based in models, monitoring the residues coming from the models adjustment ARIMA, follow up the process variations avoiding excessive variability and making it possible the detection of abnormal behaviors, even monitoring the performance of the controller itself. With the signalling of the control charts, an interference in the equation of adjustment of the controller is performed. Applying the numerical simulation, the controller behaviors are analyzed and this combined with the control charts. Intentionally inserted failures, in each controlled variable, were properly signalized. These signallings have happened even in situations where the variables were kept by the controller within the specification.. To the self-adjustment system, the increase of contribution gains of the control charts has provided greater accuracy of the controlled variables. The integration proposed has presented better results, in relation to maintain of the exit variables next to their targets, when compared to the controller operating in isolation.

El presente proyecto profesional realizado a fines del año 2013 trata sobre el rediseño de procesos expresado en diagramas de flujo de la empresa automotriz Diamante del Pacífico S.A., representante de la marca japonesa Daihatsu y la marca peruana IncaPower; esta última creada para englobar las marcas chinas Baw, Gonow, Forland, Changan y Beiben. La Empresa se dedica a la comercialización de autopartes y vehículos de pasajeros y de carga bajo la razón social Diamante del Pacífico S.A., pero el servicio técnico de taller, que involucra taller de mantenimiento, reparación de averías, auxilio mecánico y de siniestros, la realiza bajo la razón social Toyohatsu S.A. La Empresa cuenta con una amplia red de puntos de venta en Lima y a nivel nacional, pero solo los de Lima y Arequipa son propios, todos los demás son concesiones hechas a terceros. Cabe mencionar que la Empresa solo realiza el servicio de taller en el local de Surquillo para la marca Daihatsu y en el local de Villa El Salvador para IncaPower. Como alcance del trabajo es de mencionar que solo se limita a la mejora de los procesos internos de la Empresa con la ayuda de la confección de los diagramas de flujo antes y después del rediseño; no abarca la parte de la rentabilidad del negocio, el plan estratégico, comercial ni de marketing. Solo se enfoca a la eficiencia interna.
Trabajo profesional teóricamente fundamentado

It is a difficult challenge to develop a feedback control system for Statistical Process Control (SPC) because there is no effective method that can be used to calculate the accurate magnitude of feedback control actions in traditional SPC. Suitable feedback adjustments are generated from the experiences of process engineers. This drawback means that the SPC technique can not be directly applied in an automatic system. This thesis is concerned with Fuzzy Sets and Fuzzy Logic applied to the uncertainty of relationships between the SPC (early stage) alarms and SPC implementation. Based on a number of experiments of the frequency distribution for shifts of abnormal process averages and human subjective decision, a Fuzzy-SPC control system is developed to generate the magnitude of feedback control actions using fuzzy inference. A simulation study which is written in C++ is designed to implement a Fuzzy-SPC controller with satisfactory results. To further reduce the control errors, a NeuroFuzzy network is employed to build NNFuzzy- SPC system in MATLAB. The advantage of the leaning capability of Neural Networks is used to optimise the parameters of the Fuzzy- X and Fuzzy-J? controllers in order to obtain the ideal consequent membership functions to adapt to the randomness of various processes. Simulation results show that the NN-Fuzzy-SPC control system has high control accuracy and stable repeatability. To further improve the practicability of a NN-Fuzzy-SPC system, a combined forecaster with EWMA chart and digital filter is designed to reduce the NN-Fuzzy-SPC control delay. For the EWMA chart, the smoothing constant 0 is investigated by a number of experiments and optimised in the forecast process. The Finite Impulse Response (FIR) lowpass filter is designed to smooth the input data (signal) fluctuations in order to reduce the forecast errors. An improved NN-Fuzzy-SPC control system which shows high control accuracy and short control delay can be applied in both automatic control and online quality control.

Within the aircraft industry, a large number of the aluminium components are milled entirely from single solid billets of metal. Current practice is to machine at conservative and constant feed-rates. This avoids damage to the workpiece and therefore reduces costly scrap. On-board monitoring systems on milling machines within the aerospace industry have introduced the possibility of continuously and adaptively varying the feed-rate online. It is proposed that this variation could be based on cutting power. Machining parameters, such as depth and width of cut, and tool efficiency, can vary considerably during the manufacture of a single component. It is therefore likely that an adaptive controller should be used. NICS is an adaptive controller algorithm that has been under development since 1990 Stoten et al. It is known to have good properties with respect to robustness and controller performance and is therefore being investigated for use on the milling machines for aluminium components. Substructuring is a dynamic testing technique that combines numerical models and physical tests into a single hybrid experiment. Briefly, it allows the engineer to "glue" a real component (in a lab) and a virtual component (implemented on a computer) together. These real and virtual components can then be tested dynamically and in real-time as if they were a single, complete component. Hence, substructuring provides the engineer with a framework to allow testing of individual components from entire structures at full scale without requiring the complete structure to be physically present. Accurate, hi-fidelity control is essential to the successful reproduction of structures using this technique. Hence, the goal of the work presented in this thesis is the development and implementation of control strategies for use in the field of metal machining. A scheme that the controls the cutting force transmitted to aluminium workpieces by varying the feed-rate is developed. A requirement of this scheme is that it be simple to set up and implement whilst, at the same time, regulate the cutting power in the face of process para peter variations. The ability of the adaptive controller to meet these requirements is demonstrated both in simulation and on a pilot rig developed in the work. A model that relates peak cutting force to measured cutting power is developed for use with the aforementioned control scherne along with high-level control software implementing this scheme. Rirther, controllers both fixed-gain and adaptive, are developed and tailored for use in the substructuring technique. The performance of the developed controllers is investigated both in simulation and in the laboratory on a linear large-scale hydraulic system. The advantages of using the adaptive controller scheme over a fixed-gain linear equivalent are presented. An example demonstrating the use of the substructuring technique in the field of machining is discussed, including a specific application.

The thesis is focused on the production management company XY. In the first part, there is the theoretical knowledge required for the understanding of this problem and diploma thesis. In the second part there is the analysis of company processes. Based on the identified problems the methodology of improvement is designed in this section.

Orientadores: Sandra Lucia da Cruz, João Alexandre F. R. Pereira
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica
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Resumo: Os processos em batelada são largamente empregados nas indústrias de Química Fina, produtos bioquímicos, polímeros e fármacos. As plantas em batelada tendem a crescer, já que esse tipo de configuração apresenta características que são desejáveis nas chamadas "plantas do futuro": flexibilidade operacional, resposta rápida às exigências do mercado, capacidade de processar produtos de alta pureza e alto valor agregado. A destilação em batelada, em particular, é a operação unitária mais freqüentemente utilizada nas plantas em batelada. Algumas dificuldades encontradas na sua automação são: fortes não-linearidades, desvios entre o modelo e o processo, ganhos variáveis no tempo, presença de ruídos nas medidas, analisadores de composição "on-line" complexos ou lentos, estimativa do estado do sistema dificil e cara em termos computacionais. O controle de colunas de destilação contínuas de alta pureza é um tópico bastante abordado na literatura. Porém, trabalhos sobre destilação em batelada de alta pureza são escassos e, normalmente, apenas simulações são apresentadas. Esse trabalho teve como objetivo o desenvolvimento de um sistema de controle por inferência para colunas de destilação em batelada de alta pureza robusto às dificuldades de automação encontradas na prática. O algoritmo de controle foi testado por simulação e, para confirmar a aplicabilidade do controlador desenvolvido, corridas experimentais foram realizadas numa coluna de destilação em batelada em escala piloto. Um Filtro de Kalman Estendido (FKE) para colunas de destilação em batelada foi desenvolvido para fornecer estimativas de composições instantâneas a partir de algumas medidas de temperatura. O FKE foi combinado a uma estratégia de controle baseada na estrutura GLC ("Globa1ly Linearizing Control"), resultando num sistema de controle por inferência que mantém constante a composição do produto de topo de colunas de destilação em batelada de alta pureza. O controlador GLC foi testado numa coluna de destilação em batelada em escala piloto com 29 pratos perfurados. As corridas experimentais foram realizadas com o sistema etanol/l-propanol. A interface entre o computador e o processo foi feita através de uma placa ADIDA. Termopares foram utilizados para medir temperaturas instantâneas em alguns estágios da coluna. A cada período de amostragem, o FKE fornece valores de composição instantâneos, utilizando os dados de temperatura lidos pelo computador. Com o objetivo de manter a pureza do produto de topo no valor especificado, o controlador GLC atualiza a razão de refluxo baseado nas estimativas mais recentes de composição. A razão de refluxo calculada é, então, implementada pelo computador que controla a posição e o tempo de abertura da válvula magnética de refluxo. O número de sensores e o intervalo de integração do modelo da coluna foram variáveis importantes no projeto do FKE. Convergência mais rápida e estimativas mais exatas foram obtidas aumentando-se o número de sensores e/ou reduzindo-se o intervalo de integração. No entanto, acima de um certo número de sensores, as melhorias na exatidão das estimativas são insignificantes. Nas corridas em malha fechada, a variável manipulada (razão de refluxo) apresentou um comportamento do tipo liga/desliga quando os sensores de temperatura foram posicionados nos estágios próximos ao topo da coluna, onde as variações de temperatura são pequenas. Afastando-se os sensores do topo da coluna, perfis mais suaves das variáveis manipulada e controlada foram observados e desvios inferiores a 0,2% entre a composição média do destilado estimada e a composição média do destilado medida foram obtidos. Para o controle da composição do destilado de alta pureza, os sensores devem ficar afastados do topo, mas não tão distantes a ponto de diminuir a exatidão das estimativas de composição. Devido à sua robustez em relação aos desvios entre o modelo e o processo, incerteza nas condições iniciais da coluna e a presença de ruídos nas medidas de temperatura, o controlador por inferência desenvolvido nesse trabalho, além de ser flexível, mostrou-se eficaz em aplicações práticas
Abstract: Batch processing has been widely used in the production of fine chemicaIs, biochemicals, polymers and phannaceuticals. Batch configurations present features which are desirable in the ca1led "future plants": flexibility of operation, rapid response to changing market demands, suitability for manufacturing high-quality and high value-added products. Batch distillation is the most frequent separation method in batch processes. Some ofthe challenges to be faced in the automation ofbatch plants are: pronounced nonHnearities, process/model mismatch, time varying process gains, presence of measurement noise, on-line sensors are unavailable or give delayed results, state estimation is difficult and computationally expensive. While the control of high-purity continuous distillation column is a subject often addressed in literature, there are very few papers regarding the control of high-purity batch distillation units. This work aimed to develop an inferential control system for high-purity batch distillation colurnns, which is able to cape with the automation difficulties common1yencountered in practice. The control algorithm was first tested by simulation and then experimental runs were carried out in a pilot-scale batch distillation column to confirm the practical appHcability ofthe designed inferential control system. An Extended Kalman Filter (EKF) for batch distillation columns was developed to provide fast and reHable instantaneous composition values from few temperature measurements. The EKF was then combined with a control strategy based on the Globally Linearizing Control (GLC) structure, resulting in an inferential control system for constant distillate operation of high-purity batch distillation columns. The GLC controller was tested in a pilot-scale batch distillation column with 29 sieve trays. The separation of ethanol/l-propanol mixtures were considered in the experimental runs. The interface between the computer and the process was achieved by an AD/DA converter. Thennocouples were used to measure instantaneous temperature values at some column stages. At each sampling period, the EKF provides instantaneous composition values from the temperature data the computer acquires. In order to keep the product quality at the set-point, the GLC controller updates the reflux ratio using the composition estimates, and the computer controls the position ofthe reflux magnetic valve to implement the calculated reflux ratio. The number of sensors and the model integration interval showed to be important variables in the design ofthe EKF. Faster convergence and more accurate estimates were obtained by increasing the number of sensors and/or reducing the integration intervalo However, above a certain number of sensors the improvement in the EKF performance may not be significant. Spiky reflux ratio profiles were observed when sensors were placed next to the top stages, where the temperature variations are small. As the sensors were placed further from the top stages, smoother manipulated and controlled variable profiles were obtained and the distillate product met the specified purity. The inferential control system achieved tight composition control. The selection of the sensors locations must be a trade-off between obtaining noise reduction and guaranteeing that the EKF will provide acceptable estimate accuracy. Due to its robustness with regards to plant model mismatch, uncertainty in the initial system state and measurement errors, the proposed inferential control scheme is flexible and demonstrated to be feasible for practical on-line applications
Doutorado
Sistemas de Processos Quimicos e Informatica
Doutor em Engenharia Química

Orientador: Barbara Janet Teruel Mederos
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agricola
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Resumo: Este trabalho consiste no estudo da implementação de um controlador clássico utilizando o método de sintonia denominado por IMC (Controle de Modelo Interno, derivado do termo inglês Internal Model Control), visando à redução do consumo de energia elétrica que decorra na adequada relação entre este consumo e tempo de esfriamento do processo de resfriamento com ar forçado. Para isto, o sistema supervisório instalado é capaz de manipular a variável de freqüência do sinal de alimentação do motor de indução trifásico do exaustor (módulo de ar forçado), para acelerar ou desacelerar a perda de calor do produto a ser resfriado por intermédio da variação da vazão de ar que perpassa a massa deste produto. Obteve-se como resultado uma redução no consumo de energia elétrica de 64% e um acréscimo de apenas 8% no tempo de resfriamento para o sistema utilizando o controlador PI/IMC (Proporcional - Integral, com método de sintonia IMC), quando comparado ao sistema em seu funcionamento nominal. Ou seja, sistema que, nominalmente, consume 2,41 kWh para resfriar o produto em 58 minutos, consume 0,87 kWh para resfriar o produto em 63 minutos quando se emprega o controlador que utiliza o método IMC. Este controlador PI/IMC é passível de ser implementado diretamente em alguns modelos comerciais de inversores de freqüência, sem a necessidade de compra de um computador ou controlador lógico programável (CLP), tornando-o mais viável economicamente
Abstract: This work is a study of a classical controller implementation using tuning method referred to as IMC (Internal Model Control), aimed at reducing electrical energy consumption that proceed the appropriate relation between this consumption and cooling time of the cooling process with forced air. For this, the supervisory system installed is able to manipulate the variable of frequency signal power of the exhaust fan engine (forced air module), to accelerate or decelerate the loss of heat from the product to be cooled through of air flow variation that passes through the mass of this product. The results demonstrated a reduction in energy consumption from 64% and an increase of only 8% in the cooling time to the system using PI/IMC (Proportional - Integral with IMC tuning method) compared with the system in its operating nominal condition. In other words, the system, in nominal condition, consumes 2.41 kWh to cool the product in 58 minutes, but when it employs the controller using the IMC method, the system consumes 0.87 kWh to cool the product in 63 minutes. This PI/IMC controller may be implemented directly in some frequency inverter, without the need to purchase a computer or PLC (programmable logic controller), making it more economically viable
Mestrado
Maquinas Agricolas
Mestre em Engenharia Agrícola

As colunas depropanizadoras existentes nas refinarias de petróleo têm como função a separação entre as correntes de propano e butano. O objetivo de controle nestas colunas é a especificação de um teor máximo de iso-butano e mais pesados (C4 +) na corrente de propano e do teor máximo de propano e mais leves (C3 -) na corrente de butano. Controladores multivariáveis tradicionais, que normalmente são implementados nas colunas depropanizadoras, apresentam grande dificuldade para manter os produtos dentro de suas especificações, isto se deve ao fato de que este processo apresenta um comportamento bastante não-linear ao longo de toda sua região de operação. Neste trabalho temos como objetivo estudar as dificuldades encontradas no projeto de controle para esse tipo de sistema e implantar na planta industrial um controlador multivariável utilizando múltiplos modelos para controle da coluna. Para realizarmos este estudo utilizamos o simulador de processos HYSYSÔ para verificarmos o comportamento estático e dinâmico do processo. Os modelos utilizados para representar o processo são aqueles obtidos durante o estudo do comportamento dinâmico. Para implantação do controlador na unidade industrial é utilizado o SICON (Sistema de Controle da Petrobras) sendo algumas de suas rotinas modificadas para permitir a inclusão dos múltiplos modelos. Durante o estudo são comparadas as performances dos controladores QDMC e MMPC (Multi-Model Predictive Control) resolvido através de um algoritmo para NLP (Non Linear Programming). O controlador multimodelos (MMPC) é apresentado na forma de variáveis de estado podendo controlar sistemas de grande porte, inclusive sistemas com dinâmicas lentas e rápidas. Esta formulação permite prever as variáveis controladas em instantes de tempo esparsos e diferentes para cada controlada. O MMPC é capaz de tratar problemas de controle não-linear usando modelos lineares, introduzindo o conceito de robustez com a utilização do conjunto de modelos. O MMPC exige um menor esforço de sintonia que o QDMC sendo adequado para uma região mais ampla de operação.
Depropanizer columns are used in oil refineries for the separation of the propane stream from the butane stream. The control objective of these columns is the specification of a maximum content of iso-butane and heavier components (C4+) in the propane product and the maximum content of propane and lighter components (C3-) in the butane roduct. Multivariable controllers usually mplemented in depropanizer columns frequently resent great difficulty to maintain the products inside their specification ranges. This deficiency is due to the fact that the process presents a quite non-linear behavior along its operating window. The objective of the present work is to study the difficulties found in the design of the control system for the aforesaid process, and to implement in an industrial plant a multivariable controller using multiple models for the control of the separation column. To accomplish this study we used the HYSYSÔ process simulator to verify the static and dynamic behavior of the process. The models used to represent the real process in the controller are those obtained during the study of the dynamic behavior. The controller implementation in the industrial unit was done with SICON (Control System of Petrobras), which had some of its routines modified to allow the inclusion of multiple models. Along the work, performances of QDMC and MMPC(Multi-Model Predictive Control) controllers were compared. MMPC was solved through an algorithm for NLP (Non Linear Programming). The Multi-Model (MMPC) controller was implemented using a state space formulation which allows for the implementation of very large systems and besides, systems with simultaneous slow and fast dynamics. This formulation allows to foresee the controlled variables at sparse sample instants, that can be distinct for each controlled variable. MMPC is able to handle non-linear control problems using linear models by introducing the robustness concept with the use of a set of models. MMPC demands a smaller tuning effort than QDMC, and can be adapted to a wide range of operating conditions.

The thesis is divided into three parts. Theoretical part defines particular concepts as process, process control or controlling. Practical part contains a company profile and an analysis of current method of costing. In the third part opportunities for improvement of the method of costing are designed.

Cutting forces in the milling process vary depending on the work-piece geometry and cutting parameters. When the cutting forces exceed a certain limit, the tool may break and cause damage to the work-piece and eventually to the machine tool. Adaptive cutting force control systems can be used to manipulate cutting operation parameters in order to keep the cutting forces at a safe level. Successful application of the method leads to increased metal removal rate and productivity in machining processes. In this thesis, a second order transfer function is used to represent the time invariant dynamics of a research milling machine's feed drive servo system. The command feed velocity is the input and the actual feed is the output of the servo system. The actual feed manipulates the cutting forces which are modelled by a first order time varying dynamic system. Three existing adaptive control methods have been designed to control the milling process. Adaptive Proportional Integral Derivative (PID), Pole-Placement and Model Reference Adaptive Control (MRAC) algorithms have been simulated and experimentally verified. It has been shown that when the dynamics of both the time invariant servo and the time variant cutting process are modelled correctly, the adaptive control algorithms can perform well. Simulations and experiments, which have been carried out with identical cutting conditions, show that PID and Pole-Placement controllers can be successfully applied to milling force control.
Applied Science, Faculty of
Mechanical Engineering, Department of
Graduate

The project focuses on the packaging process of the smart card manufacturing industry. The idea of the project concerns how to increase production packaging efficiency by introducing a control system. After taking an in-depth look at the current production environment, the following system goals were defined: packaging time reduction, cost reduction, decrease in human errors, and reducing the number of customer complaints. To achieve these goals, the thesis project was divided into the following tasks: discovering a feasible solution, actual system development, testing, and evaluation. The proposed system is based on hardware (i.e. barcode scanner, and barcode printer) integrated with customized control software. The barcode scanner acts as a bridge between the system and the production process by scanning a barcode printed on each product. The system prints the required information label for the product’s package according to the scanned product. This label is pasted on the product’s box and is used as a tracking tool during further production steps. The system is very flexible and suits any packaging model. Other functional properties maintained in the system include data security, product traceability, and real time production monitoring. Testing of the system was done in an actual production environment at an Oberthur Technologies manufacturing site. Two production lines were selected to test the system’s functionality, specifically the SIM card production packaging line and the Scratch card/ Bank Card production packaging line. The results obtained during the evaluation phase of the proposed system show that the proposed solution decreased the packaging processing time by (27.3%) over the previous values. Moreover, the resulting human error rate is close to (zero%).
Projektet fokuserar på förpackningen processen smartkortet tillverkningsindustrin. Tanken med projektet handlar om hur att öka effektiviteten produktionen förpackningar genom att införa ett styrsystem. Efter att ha tagit en fördjupad titt på den nuvarande produktionsmiljö, var följande systemkrav mål definieras: nedsättning förpackning tid, minskade kostnader, minskad mänskliga fel och minska antalet kundklagomål. För att uppnå dessa mål var examensarbetet indelad i följande uppgifter: att upptäcka en genomförbar lösning, faktisk systemutveckling, testning och utvärdering. Det föreslagna systemet bygger på hårdvara (dvs streckkodsläsare och streckkod skrivare) integreras med skräddarsydd styrprogram. Den streckkodsläsare fungerar som en bro mellan systemet och produktionsprocessen genom att läsa en streckkod tryckt på varje produkt. Systemet skriver den erforderliga informationen etiketten för produktens förpackning enligt den scannade produkten. Denna etikett klistras in på produktens ask och används som ett verktyg för spårning under ytterligare produktionssteg. Systemet är mycket flexibelt och passar varje förpackning modell. Andra funktionella egenskaper bibehålls i systemet inkluderar datasäkerhet, spårbarhet och i realtid övervakning av produktionen. Testning av systemet gjordes i en verklig produktionsmiljö i ett Oberthur Technologies tillverkningsanläggning. Två produktionslinjer valdes för att testa systemets funktionalitet, särskilt i SIM-kortet produktionen förpackning linje och skrapkort / Bank kortproduktion förpackningslinje. De resultat som erhållits under utvärderingsfasen av det föreslagna systemet visar att den föreslagna lösningen minskade tiden förpackningen behandling av (27,3 %) jämfört med föregående värden. Dessutom är den resulterande mänskliga fel som ligger nära (noll %).

A signicant growth was witnessed in the led of Wireless Sensor Networks (WSNs), the previous decade. Advances in hardware miniaturization coupled with increased processing capabilities and memory capacity have extended the application domains of WSNs. In light of this, standardization organizations led by academia and industries initiated activities for the design of protocols such as IEEE 802.15.4 and IETF RPL (Routing Protocol for Low power and Lossy Networks). IEEE 802.15.4 denes physical and media access layers for WSNs while IETF RPL denes the functionality of the routing layer. This thesis investigates research issues in wireless sensor networks and network controlled systems that control micro-biological processes for water treatment plants. By choosing a process model that can relate to an industrial process, feasibility of control over IEEE 802.15.4 and RPL protocols is evaluated for stability with regards to network delay and packet loss. Settling time and overshoot are measured to indicate control performance. Control messages related to routing and routing table lengths are measured to indicate network stability and scalability. The system model used is a centralized discrete controller controlling a thermal processes running on the sensors. This model is chosen for representing wide industrial networked control systems while adding a WSN dimension based on IEEE 802.15.4 and RPL. The main contribution of this thesis is an experimental study where both the network and controller performance is validated while utilizing commercial o-theshelf sensor platforms. The results from this experimental work include rst the use of established theorems for analyzing control using WSNs. Moreover, the ability of IEEE 802.15.4 and RPL to provide stable communication that is reliable enough for actual industrial control implementation is validated.

University of Central Florida College of Engineering Thesis
This report documents a Process Control Language. It was written to provide an easy-to-use, user-friendly language to control a manufacturing-type process. It is not assumed the user is proficient or even familiar with any computer languages. The user should be able to grasp the simple set of commands available and begin writing user programs in a short period of time. Emphasis has been placed on error messages to inform the user of the type of error and enough information to correct it. The language was written in PDP-11 assembly language and run on a 11/34 computer in the Microcomputer Laboratory at the University of Central Florida.
M.S.;
Engineering;
Engineering;
Engineering;
46 p.
iv, 46 leaves, bound : ill. ; 28 cm.

CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
Processos Multicanal (PMC) estão presentes nas linhas de produção de muitos segmentos industriais, tais como na indústria alimentícia, farmacêutica, de fabricação de aço e de papel. No entanto, há poucos trabalhos na literatura dedicados ao controle estatístico de processos dessa natureza. O trabalho de Boyd (1950) é o primeiro deles. Neste trabalho são descritos os gráficos de controle de grupos (GCG). Este é o procedimento tradicional, recomendado em textos didáticos de CEP como Pyzdek (1992) e Montgomery (até a 3a edição, de 1997). Posteriormente, Mortell e Runger (1995) elaboram um modelo matemático mais realista para PMC, decompondo a fonte de variação do processo em duas componentes distintas: uma, comum a todos os canais e outra, correspondendo à variação individual de cada canal do processo. Tal modelo foi tão bem aceito na literatura que, desde a sua publicação, tem sido utilizado para o desenvolvimento de esquemas de controle mais eficientes para PMC. Dos esquemas desenvolvidos na versão Shewhart, para o controle estatístico das médias das componentes individuais de variação, devem ser destacados os gráficos de controle de Mortell e Runger (1995), de Runger, Alt e Montgomery (1996) e o GCG de Barbosa (2008). Dentre os esquemas mencionados, somente os dois primeiros foram desenvolvidos tanto em uma versão de Shewhart como em uma versão EWMA (Exponentially Weighted Moving Average), visando obter maior sensibilidade a pequenas alterações na média. Esta tese traz novas propostas para PMC bem representados pelo modelo de Mortell e Runger (1995). Propõe-se a análise da eficiência dos gráficos de controle existentes na detecção de aumentos na dispersão de um canal, bem como o desenvolvimento, na versão Shewhart e EWMA, de novos GCG especificamente destinados à sinalização de tais aumentos. Quando não é viável obter mais de uma observação por canal do processo, propõem-se os gráficos: GCG de MR das diferenças em relação ao nível-base (DNB) e GCG EWMA MR DNB. Já para as situações em que é possível obter mais de uma observação por canal, propõem-se: GCG de S(2) e GCG EWMA de ln[S(2)]. É importante ressaltar que todos os trabalhos desenvolvidos na literatura (seguindo o modelo de Mortell e Runger, 1995) foram dedicados exclusivamente ao controle estatístico da média das componentes individuais de variação, portanto, esta tese tem caráter inédito. Além das contribuições mencionadas, visando obter maior sensibilidade a alterações de pequena magnitude na média das componentes individuais, propõe-se e analisa-se uma versão EWMA do GCG de Barbosa (2008), o mais eficiente na versão Shewhart. Adicionalmente, para obter esquemas EWMA mais eficientes, são obtidos os projetos ótimos de todos os esquemas EWMA apresentados nesta tese, incluindo os gráficos de controle de EWMA de R(t) de Mortell e Runger (1995) e de MEWMA de S(2) de Runger, Alt e Montgomery (1996). São analisadas as curvas de desempenho de todos os esquemas de controle para uma variedade de situações. Nas análises de desempenho, pode-se observar que os esquemas propostos nesta tese são os mais eficientes.
In a multiple stream process (MSP), a same quality variable is measured in several streams in parallel. The first tool proposed for monitoring MSPs was the Group Control Chart (GCC) by Boyd (1950). These schemes are recommended in textbooks and guides as Pyzdek (1992) and Montgomery (until 3rd edition, 1997). Its efficiency is impaired by the presence of cross correlation between streams. A useful model for MSPs (Mortell and Runger, 1995) represents the value of the quality variable in each stream at any time t as the sum of a random variable (or stochastic process) but that is common to all streams, which can be called base level, plus the individual variation of each stream relative to the base level. In the literature, three different Shewhart schemes were developed to control the individual variation of each stream: Mortell e Runger (1995), Runger, Alt and Montgomery (1996) and Barbosa (2008). Only the two first ones were developed both in a Shewhart-type and a EWMA (Exponentially Weighted Moving Average) version. All these schemes were devoted to monitoring the mean of the individual components of the streams; to the best of our knowledge, no previous work considered the case of increases in the variance of a stream. In this thesis four different GCCs for monitoring the inner variability of the individual streams are developed: a GCC of S(2), the sample variance of each stream (which is not the same as Runger, Alt and Montgomery’s statistics); a GCC of EWMA[lnS(2)]; a GCC of the Moving Ranges of the residuals of each stream to the estimated base level, and an EWMA version of it. The last two GCCs cater for the case where, at every sampling time, only individual observations per stream are feasible, which is frequent with a large number of streams. Beyond the mentioned contributions, aiming at more sensitivity to the small shifts in the mean of the individual components, this work proposes a EWMA version of the GCC by Barbosa (2008), the most efficient in the Shewhart version. The ARL performance of every one of these schemes is analyzed, in a variety of situations, including the case of increases in the variance of one stream when the schemes are designed for monitoring the means of individual streams. The results show that the proposed schemes are the fastest in detecting special causes that affect one individual stream.

To support concurrent design a framework for hierarchical design of a process operating system is developed. A process operating system is defined as the complete collection of control schemes, alarms and operating procedures used for managing the process through all phases of operation. The design of an integrated operating system is approached by decomposing the problem into a hierarchy of operating tasks. Three classes of operating task are identified: regulatory tasks for optimising operation at a steady state, transition tasks for transferring the process from one regulatory state to another and executive tasks which manage the response to discrete events such as alarms and failures. Operating tasks define the requirements for optimisation and failure management. The implementation of an operating task is achieved by the design of a control scheme for which a generic structure has been developed. The structure emphasises the use of explicit models with parameter estimation and control distribution blocks providing the interface between the abstract model used for optimisation and the reality of the underlying system. A knowledge based representation has been developed to support operating system design. Particular attention has been given to the problem of supporting concurrent design of the process and operating system. A representation has been developed that links process design alternatives with operating system design alternatives by their association with a common operating task. A case study that considers the design of a hierarchical operating system for a hydrofluoric acid plant is included in this thesis. The study demonstrates how the operating system may be developed in step with the process design. The hierarchical development of the process is used to help formulate the operating tasks for the operating system design. Through design of the operating system it is possible to provide focused feedback on the process operability requirements. The final operating system structure demonstrates how failure management and optimisation are integrated together.

Ultrasound has found application in chemical processing control using both low power, high frequency monitoring techniques and high power, low frequency process enhancement approaches. In many cases, standard ultrasonic systems are retrofitted to a process and while these produce efficiency improvements, the design of bespoke systems may offer more potential. In particular, this Thesis has considered two techniques used in the biomedical field; harmonic imaging and high intensity focused ultrasound (HIFU) and has translated these into ultrasonic transducers for use in an industrial process control system. Traditional ultrasound monitoring techniques are based on operation in the linear domain and are used to monitor chemical processes by measurement of material acoustic velocity, attenuation or based on spectral analysis. Both active and passive methods have been reported for application in this industrial sector. One issue is the presence of multiple reflections in the received ultrasonic signal which can mask the signals of interest from the load medium. This Thesis has considered a new ultrasonic monitoring approach using a combination of both linear and nonlinear spectral components. This was applied to high-throughput products and a dual frequency transducer designed and fabricated to acquire the ultrasonic backscattered signals in both the fundamental and second harmonic frequency regimes. The additional information provided by the harmonic device enabled discrimination between shampoo and conditioner products with the same density, but different molecular weights. HIFU transducer array designs are then considered for high power, low frequency chemical process enhancement applications. Typical applications of high power ultrasound use single or multiple discrete transducers to insonify a process. These are effective, but inflexible in the delivery of the ultrasonic field. The application of a HIFU array would provide control of the high power focal region in the load medium, which offer advantages to industry. Two transducer array approaches have been considered in this Thesis based on piezoelectric composite configurations. Three HIFU arrays based on the 1-3 piezocomposite have been fabricated to operate between 200-400kHz and fully characterised to evaluate their high power performance. A second transducer configuration was based on a novel 2-2 piezocomposite with a 2 layer stacked configuration. Simulation of this transducer design illustrated its potential for high power applications, although a number of fabrication issues resulted in the manufactured array not operating at full capacity. Importantly, the transducer configurations developed in this Thesis are shown to induce cavitation through the standard aluminium foil test.