A otimização de processos vem se tornando uma ferramenta fundamental para o aumento da lucratividade das plantas químicas. Diversos métodos de otimização foram propostos ao longo dos anos, sendo que a otimização em tempo real (RTO) é a solução mais consolidada industrialmente, enquanto que o self-optimizing control (SOC) surge como uma alternativa simplificada, com um menor custo de implantação em relação a esse. Neste trabalho são estudados diversos aspectos da metodologia de SOC, iniciando pela análise do impacto do ponto de operação para o desenvolvimento de estruturas de controle auto-otimizáveis. São propostas modificações na formulação do problema de otimização de SOC de modo que as variáveis controladas sejam determinadas no mesmo problema de otimização em que é escolhido o ponto de operação, permitindo a redução da perda do processo. De forma a analisar a influência da dinâmica nos resultados obtidos, é realizado um estudo comparativo da perda gerada no processo ao longo da operação para as estruturas de otimização baseadas em RTO e em SOC. Com base nos resultados obtidos para uma unidade didática, mostra-se que o comportamento dinâmico do distúrbio possui grande influência na escolha da técnica de otimização, quebrando a ideia de que o RTO é um limite superior do SOC. A aplicação industrial das técnicas clássicas de SOC é validada em uma unidade de separação de propeno, baseada em uma unidade real em operação. A partir da modelagem do processo em simulador comercial, foram geradas as variáveis controladas que permitam uma perda aceitável para a unidade, comprovando a viabilidade de implantação da metodologia em unidades reais. / Process optimization has become a fundamental tool for increasing chemical plants profit. Several optimization methods have been proposed over the years, and real-time optimization (RTO) is the most consolidated solution industrially while self-optimizing control (SOC) appears as a simplified alternative with a lower implementation cost. In this work several aspects of SOC methodology are studied, starting from the analysis of the impact of operating point in the development of self-optimizing control structures. Improvements are proposed in SOC optimization problem formulation where controlled variables are determined in the same optimization problem that operating point, thus reducing significantly process loss. In order to analyze the influence of dynamics on the results, a comparative study is accomplished comparing the loss generated in the process throughout the operation for optimization structures based on RTO and SOC. With the results generated for a toy unit, it is shown that the disturbance dynamic behavior has a great influence on choosing the optimization technique, breaking the idea that RTO is an upper limit of SOC. The industrial application of classical SOC techniques is tested on a propylene separation unit, really operating nowadays. The process was modelled in a commercial simulator and with this model it was generated the best set of controlled variables, based on SOC, that achieve an acceptable loss for the unit, showing that the methodology can be applied in in real units.

O presente trabalho aborda o desenvolvimento de um sistema eletrônico de controle em tempo real para servoposicionadores pneumáticos baseado em microcontroladores. Os servoposicionadores pneumáticos, por apresentarem características tais como baixo preço, por serem não poluentes e de fácil utilização, além de apresentarem boa relação peso/potência, são atraentes para utilização na área de robótica. Entretanto, devido às suas não-linearidades inerentes, os servoposicionadores pneumáticos apresentam dificuldades que devem ser superadas para a sua adequada utilização em atividade de posicionamento preciso. Assim, visando compensá-las, estão sendo atualmente desenvolvidos algoritmos e técnicas cada vez mais complexas que exigem, por isso, ferramentas programáveis de controle com cada vez maior poder de processamento. Este trabalho apresenta, a partir de uma revisão bibliográfica, as soluções mais utilizadas para o controle digital de sistemas automáticos e de estudos sobre os dispositivos e componentes disponíveis no mercado, uma proposta econômica para o controle em tempo real de servoposicionadores pneumáticos. Para verificar a eficiência da solução proposta, a arquitetura de controle desenvolvida foi utilizada para o controle de um servoposicionador pneumático. Para tanto, projetou-se e programou-se o tradicional controlador linear PID (Proporcional – Integral – Derivativo) e o controle não linear a estrutura variável baseado em modos deslizantes (Slide Mode Control). A partir dos resultados apresentados e das suas discussões pode-se avaliar o desempenho da arquitetura desenvolvida no controle do servoposicionador pneumático. / This work discusses the development of an electronic real-time control system for microcontroller-based pneumatic servopositioners. The servopositioners offer attractive characteristics for use in robotics, such as low price, non-polluting operation, being easy to use and with a good power/weight ratio. However, due to their inherent non-linearities, the servopositioners present difficulties in precise positioning applications. To compensate these difficulties, the use of complex algorithms and new techniques are currently being availed, requiring hardware for programmable control with increasing processing power. This paper presents an economic proposal for real-time control of servopositioners, starting from a literature review of the most popular solutions for digital control of automated systems and from studies of devices and commercial components currently available. To verify the efficiency of the proposed solution, the control architecture developed was used for the control of a pneumatic servopositioner. Therefore, we designed and programmed a traditional linear controller PID (Proportional – Integral – Derivative) and a nonlinear control based on variable structure sliding mode (Slide Mode Control). The results obtained in trajectory tracking tests were used to evaluate the performance of the developed architecture.

The purpose of this research is to investigate and analyse some batch arrival queueing systems with Bernoulli scheduled vacation process and single server providing service. The study aims to explore and extend the work done on vacation and unreliable queues with a combination of assumptions like balking and re-service, reneging during vacations, time homogeneous random breakdowns and fluctuating modes of service. We study the steady state properties, and also transient behaviour of such queueing systems. Due to vacations the arriving units already in the system may abandon the system without receiving any service (reneging). Customers may decide not to join the queue when the server is in either working or vacation state (balking). We study this phenomenon in the framework of two models; a single server with two types of parallel services and two stages of service. The model is further extended with re-service offered instantaneously. Units which join the queue but leave without service upon the absence of the server; especially due to vacation is quite a natural phenomenon. We study this reneging behaviour in a queueing process with a single server in the context of Markovian and non-Markovian service time distribution. Arrivals are in batches while each customer can take the decision to renege independently. The non-Markovian model is further extended considering service time to follow a Gamma distribution and arrivals are due to Geometric distribution. The closed-form solutions are derived in all the cases. Among other causes of service interruptions, one prime cause is breakdowns. We consider breakdowns to occur both in idle and working state of the server. In this queueing system the transient and steady state analysis are both investigated. Applying the supplementary variable technique, we obtain the probability generating function of queue size at random epoch for the different states of the system and also derive some performance measures like probability of server‟s idle time, utilization factor, mean queue length and mean waiting time. The effect of the parameters on some of the main performance measures is illustrated by numerical examples to validate the analytical results obtained in the study. The Mathematica 10 software has been used to provide the numerical results and presentation of the effects of some performance measures through plots and graphs.

As grandes cidades brasileiras, como São Paulo, Rio de Janeiro e Porto Alegre, sofreram um crescimento acelerado ao longo das últimas décadas. Em conseqüência, mostrou-se necessário controlar o seu planejamento, garantindo à população condições favoráveis de desenvolvimento habitacional. Para Porto Alegre/RS, o instrumento básico de controle urbanístico é o Plano Diretor de Desenvolvimento Urbano e Ambiental (PDDUA). As definições apresentadas no PDDUA identificam, a partir do início da sua vigência, uma nova tipologia arquitetônica para as várias regiões da cidade. Neste contexto, o estudo de tipologias torna-se importante, pois, além de indicar os critérios de projeto adotados em determinada época e local, pode servir de parâmetro para os estudos de viabilidade, quando da necessidade de tomada de decisão para a implantação de uma nova edificação. Em função disto, o presente trabalho tem como objetivo identificar as características geométricas típicas dos projetos arquitetônicos de edificações residenciais multifamiliares construídos em Porto Alegre/RS a partir da vigência do PDUUA. Para cumprir com o objetivo proposto, foi realizado um levantamento documental junto à Secretaria Municipal de Obras e Viação da Prefeitura Municipal de Porto Alegre/RS (SMOV/PMPA) onde, a partir de uma população de projetos elaborados seguindo as diretrizes do PDDUA, foram realizadas análises com uma amostra de projetos estatisticamente representativa. Como na amostra houve grande concentração de projetos localizados nas Macrozonas 1 e 3, as edificações destas regiões da cidade foram detalhadamente estudadas. Os aspectos analisados procuraram englobar os principais elementos arquitetônicos dos projetos constituintes da amostra. Dentre os resultados alcançados, cabe salientar que a área total projetada, a presença de apartamento de zelador, a área útil total das unidades privativas e o número de dependências apresentam resultados diferentes segundo a localização. Além disso, os apartamentos de 3 dormitórios possuem, de maneira geral, valores de área superiores aos apartamentos de 2 dormitórios. Confirmam-se, assim, decisões de projeto particulares segundo a região. / Brazilian big cities, like São Paulo, Rio de Janeiro and Porto Alegre, have suffered accelerated growth throughout the last decades. Due to this growth, it has been necessary to control city planning, in order to guarantee favorable conditions of housing development for the population. In Porto Alegre/RS, the basic instrument of urban building control is the Management Plan of Urban and Environmental Development (PDDUA). The definitions presented in the PDDUA identify, from the beginning of its validity, a new architectural standard for the various regions of the city. In this context, the study of the standards has become important, for, besides indicating the project criteria to be adopted in determined time and place, they can serve as parameter for viable studies, when making planning decisions for the implementation of a new construction. For this reason, the present work has, as objective, to identify the typically geometric characteristics found in the architectural projects of multifamily residential constructions built in Porto Alegre /RS from the validity date of the PDUUA. To fulfill the considered objective, a documentary survey was carried out along with the City Department of Work and Means of Transportation of the Municipal City Hall of Porto Alegre /RS (SMOV/PMPA) where a statistically valid sample was selected from a population of elaborated projects which follow the norms of the PDDUA. As in the sample there was great concentration of projects located in Macrozones 1 and 3, the projects of these areas of the city were studied in detail. The analyzed aspects tried to include the main architectural elements of the constituent projects of the sample. Amongst the results reached, the projected total area, the presence of keeper's apartment, the useful total area of the apartments and the number of dependences present different results according to the location. Besides, apartments with 3 bedrooms possess, in a general way, higher area values than apartments with 2 bedrooms. Thus, it confirms different decisions according to the region.

abstract: The primary function of the medium access control (MAC) protocol is managing access to a shared communication channel. From the viewpoint of transmitters, the MAC protocol determines each transmitter's persistence, the fraction of time it is permitted to spend transmitting. Schedule-based schemes implement stable persistences, achieving low variation in delay and throughput, and sometimes bounding maximum delay. However, they adapt slowly, if at all, to changes in the network. Contention-based schemes are agile, adapting quickly to changes in perceived contention, but suffer from short-term unfairness, large variations in packet delay, and poor performance at high load. The perfect MAC protocol, it seems, embodies the strengths of both contention- and schedule-based approaches while avoiding their weaknesses. This thesis culminates in the design of a Variable-Weight and Adaptive Topology Transparent (VWATT) MAC protocol. The design of VWATT first required answers for two questions: (1) If a node is equipped with schedules of different weights, which weight should it employ? (2) How is the node to compute the desired weight in a network lacking centralized control? The first question is answered by the Topology- and Load-Aware (TLA) allocation which defines target persistences that conform to both network topology and traffic load. Simulations show the TLA allocation to outperform IEEE 802.11, improving on the expectation and variation of delay, throughput, and drop rate. The second question is answered in the design of an Adaptive Topology- and Load-Aware Scheduled (ATLAS) MAC that computes the TLA allocation in a decentralized and adaptive manner. Simulation results show that ATLAS converges quickly on the TLA allocation, supporting highly dynamic networks. With these questions answered, a construction based on transversal designs is given for a variable-weight topology transparent schedule that allows nodes to dynamically and independently select weights to accommodate local topology and traffic load. The schedule maintains a guarantee on maximum delay when the maximum neighbourhood size is not too large. The schedule is integrated with the distributed computation of ATLAS to create VWATT. Simulations indicate that VWATT offers the stable performance characteristics of a scheduled MAC while adapting quickly to changes in topology and traffic load. / Dissertation/Thesis / Ph.D. Computer Science 2013

abstract: This work presents two complementary studies that propose heuristic methods to capture characteristics of data using the ensemble learning method of random forest. The first study is motivated by the problem in education of determining teacher effectiveness in student achievement. Value-added models (VAMs), constructed as linear mixed models, use students’ test scores as outcome variables and teachers’ contributions as random effects to ascribe changes in student performance to the teachers who have taught them. The VAMs teacher score is the empirical best linear unbiased predictor (EBLUP). This approach is limited by the adequacy of the assumed model specification with respect to the unknown underlying model. In that regard, this study proposes alternative ways to rank teacher effects that are not dependent on a given model by introducing two variable importance measures (VIMs), the node-proportion and the covariate-proportion. These VIMs are novel because they take into account the final configuration of the terminal nodes in the constitutive trees in a random forest. In a simulation study, under a variety of conditions, true rankings of teacher effects are compared with estimated rankings obtained using three sources: the newly proposed VIMs, existing VIMs, and EBLUPs from the assumed linear model specification. The newly proposed VIMs outperform all others in various scenarios where the model was misspecified. The second study develops two novel interaction measures. These measures could be used within but are not restricted to the VAM framework. The distribution-based measure is constructed to identify interactions in a general setting where a model specification is not assumed in advance. In turn, the mean-based measure is built to estimate interactions when the model specification is assumed to be linear. Both measures are unique in their construction; they take into account not only the outcome values, but also the internal structure of the trees in a random forest. In a separate simulation study, under a variety of conditions, the proposed measures are found to identify and estimate second-order interactions. / Dissertation/Thesis / Ph.D. Statistics 2013

Today’s surveys face a growing problem with increasing nonresponse.  The increase in nonresponse rate causes a need for better and more effective ways to reduce the nonresponse bias.  There are three major scientific orientation of today’s research dealing with nonresponse. One is examining the social factors, the second one studies different data collection methods and the third investigating the use of weights to adjust estimators for nonresponse.  We would like to contribute to the third orientation by evaluating estimators which use and adjust weights based on auxiliary variables to balance the survey nonresponse through simulations. For the simulation we use an artificial population consisting of 35455 participants from the Representativity Indicators for Survey Quality project. We model three nonresponse mechanisms (MCAR, MAR and MNAR) with three different coefficient of determination s between our study variable and the auxiliary variables and under three response rates resulting in 63 simulation scenarios. The scenarios are replicated 1000 times to acquire the results. We outline our findings and results for each estimator in all scenarios with the help of bias measures.

O presente trabalho tem por objetivo as motivações que tencionam as organizações empresariais a adotar práticas de gestão ambiental, bem como o modo de internalização dessas práticas. Para a realização de tal intento, o projeto foi dividido em três partes principais. Na primeira parte, levou-se a cabo uma revisão da literatura pertinente, com a apresentação de um panorama histórico acerca do tratamento das questões ambientais, a apreciação dos conceitos e abordagens teóricas que a gestão ambiental empresarial vem assumindo e, o tratamento dado pela teoria econômica sobre o assunto. Na segunda parte, empreendeu-se um estudo de caso de uma organização com postura ambiental diferenciada, no qual procurou-se elucidar os aspectos relativos aos modos e motivações que levaram a instituição a adotar tal comportamento. As informações, obtidas durante o processo de coleta de dados, salientam que, apesar do posicionamento ambiental adequado da empresa, a internalização da variável ambiental é principalmente motivada por fatores econômicos-financeiros. Num primeiro instante, a empresa resguarda-se da aplicação dos dispositivos legais vigentes; em uma etapa posterior, com a visualização de oportunidades de retornos financeiros decorrentes dos ganhos em eficiência operacional como também da melhoria da imagem institucional, a empresa passa a ser mais atuante. / The present research work focus on the motivations that intend the organizations to adopt principles of environmental management, as well as the way of assimilation of these practical. For the accomplishment of such intention, the project was divided in three main parts. In the first part, it was taken handle a revision of pertinent literature, with the presentation of a historical view concerning the treatment of the environmental questions, the appreciation of the concepts and theoretical boardings that the environmental management comes assuming and, the treatment given for the economic theory on the subject. In the second part, a study case of an organization with special environmental position was undertaken, in which it was looked to elucidate the relative aspects to the ways and motivations that had taken the institution to adopt such behavior. The information, gotten during the process of collection of data, point out that, although the adjusted environmental positioning of the company, the adoption of the environmental variable mainly is motivated by economic-financial factors. In a first instant, the company is taken shelter against the application of the effective legal devices; in a posterior stage, with the visualization of chances of decurrent financial returns of the profits in operational efficiency as well as of the improvement of the institutional image, the company starts to be more operating.

A operação de adubação responde por parte significativa dos custos de produção agrícola. Melhorar a qualidade dessa operação acarreta benefícios econômicos e ambientais. O processo de adubação normalmente é realizado a uma taxa média, representativa de uma área, no entanto, propriedades químicas do solo podem variar consideravelmente dentro dessa área. Desse modo, alguns locais poderão receber fertilizantes e/ou corretivos em excesso, enquanto outros poderão receber quantidades insuficientes. A alternativa à taxa média é a realizar a aplicação à taxa variada, que se caracteriza por aplicar os insumos de acordo com as necessidades específicas dentro da área. Para que essa aplicação aconteça, mecanismos dosadores controlam a aplicação. O objetivo deste estudo é avaliar os mecanismos dosadores de uma carreta adubadora de arrasto, comportas e esteiras, atendem as prescrições de doses previstas no mapa de recomendação de adubação. Para avaliar a uniformidade da operação utilizou-se o controle estatístico do processo. De acordo com os resultados obtidos pode-se afirmar que os mecanismos dosadores não atenderam a condição de realizar a aplicação à taxa variável de maneira uniforme. / The operation fertilization accounts for a significant portion of the costs of agricultural production. Improve the quality of this operation entails economic and environmental benefits. The process of fertilization is usually performed at an average rate representative of an area, however, the chemical properties of soil can vary considerably within the area. Thus, some locations may receive fertilizer and / or lime in excess, while others may receive insufficient amounts. The alternative is to average the application to perform variable rate, characterized by applying inputs according to the specific requirements within the area. For this application happens, metering mechanisms control the application. The aim of this study is to evaluate the dosing mechanisms of a truck hauling fertilizer, locks and mats, meet the requirements of the prescribed dose map fertilizer recommendation. To evaluate the uniformity of operation used the statistical process control. According to the obtained results it can be stated that the meter mechanism did not meet the condition to perform variable rate application to uniformly.

Plant canopy sensors have emerged as a new tool for in field on-the-go spatially localized prediction of plant biomass and nitrogen (N) uptake by crops in an indirectly and plant indestructible way as base for N variable rate fertilization. Sensors based on the combination of specific reflectance bands from the electromagnetic spectrum constitute the vast majority of canopy sensors, and this principle has already been validated in many crops. Alternatively to this concept, the use of ultrasonic distance sensors to measure crop canopy height has been presented as an option to estimate biomass. Based on that, the aim of this thesis was to validate and refine canopy sensor systems on automated diagnosis of plant parameters aimed the application of N fertilizer according sugarcane needs. Therefore, it was necessary to: 1) validate the prior calibration made for the reflectance sensor (Portz et al., 2012) and to establish the best time to use the sensor over the crop; 2) test the use of the reflectance sensor in comparative strips trials of uniform and sensor based N variable rate application testing algorithms with positive and negative slope and measuring productivity at the end of the season; 3) obtain the relationship between crop canopy height with accumulated biomass and N uptake by the crop during the initial growing season; 4) explore the plant height measured with an ultrasonic sensor comparing the results of biomass and N uptake prediction with those obtained with the reflectance sensor. The experiments were conducted on commercial sugarcane fields, and in strips of the crop with N variable rate application. The experiments were installed over clayey and sandy soils in dry and rainy seasons being all evaluated with the reflectance sensor Yara N-Sensor model ALS (N-Sensor® ALS, Yara International ASA) and partly in comparison with an ultrasonic sensing system Polaroid 6500 (Polaroid, Minnetonka, MN, USA), when the crop had stalk height between 0.2 and 0.9 m. The reflectance sensor calibration fitted with the previous published data showing the interval between 0.3 - 0.5m as the most appropriate to use this sensor over sugarcane. The positive slope algorithm was superior to the negative, except in the situation of clayey soil in rainy season where the response from the negative slope algorithm was higher. The sugarcane plant height was highly correlated with biomass and N uptake by the crop, being possible to estimate the plants canopy height indirectly by the use of an ultrasonic sensor. Comparing the sensor systems, canopy reflectance was better in the early stages of crop as canopy height was more suitable for estimating the cultural parameters when the plants already covered soil in between the rows (+ 0.6 m stalk height), being the sensor systems complementary when fertilization is widely spread in the early crop growth period. / Sensores de dossel tem se apresentado como uma nova ferramenta para a predição espacialmente localizada, em tempo real, de forma indireta e indestrutiva da biomassa vegetal e extração de nitrogênio (N) pelas culturas como base para a aplicação de fertilizantes nitrogenados em taxas variáveis. Sensores baseados na combinação de faixas específicas de reflectância do espectro eletromagnético constituem a grande maioria dos sensores de dossel sendo este princípio já validado para uso em muitas culturas. Alternativamente a este conceito, a medição da altura do dossel cultural com o uso de sensor ultrassónico se apresenta como uma alternativa para a estimativa de biomassa vegetal. Com base nisso o objetivo desta tese foi de validar e aperfeiçoar sistemas sensores para a automação do diagnóstico visando à aplicação de fertilizante nitrogenado em função da necessidade da cana-de-açúcar. Para tanto, foi necessário: 1) validar a previa calibração feita ao sensor de reflectância (PORTZ et al., 2012) assim como estabelecer o melhor momento para uso do sensor na cultura; 2) ensaiar o uso do sensor em faixas comparativas entre taxa fixa e variável testando algoritmos de aplicação com inclinação positiva e negativa para dose de N mensurando produtividade; 3) obter a relação entre altura de dossel da cultura com, biomassa acumulada e extração de nitrogênio pela planta; 4) explorar a altura de plantas mensurada com um sensor ultrassónico comparando os resultados de predição de biomassa e extração de nitrogênio com aqueles obtidos com sensor de refletância. Os experimentos foram conduzidos em talhões comerciais de cana-de-açúcar e em forma de faixas da cultura, com aplicação em taxa variada de doses de N. Os experimentos foram instalados em solos de textura argilosa e arenosa nas épocas seca e chuvosa do ano sendo todos avaliados com o sensor Yara N-Sensor, modelo ALS (N-Sensor® ALS, Yara International ASA), e em parte comparando com um sistema sensor ultrassónico Polaroid 6500 (Polaroid, Minnetonka, MN, EUA) quando a cultura apresentava altura de colmos entre 0,2 e 0,9 m. Os dados coletados para a calibração do sensor de reflectância se encaixaram exatamente aos dados já publicados mostrando-se o intervalo entre 0.3 e 0.5 m o mais indicado ao uso deste sensor. O algoritmo com inclinação positiva se mostrou superior ao negativo exceto na situação de solo argiloso em estação chuvosa onde a resposta do algoritmo negativo foi maior. A altura de planta de cana-de-açúcar se mostrou altamente correlacionável com biomassa e extração de nitrogênio pela cultura, sendo possível estimar a altura do dossel das plantas de forma indireta pelo uso do sensor ultrassónico. Comparando-se os sistemas sensores, reflectância de dossel se mostrou melhor em estádios iniciais da cultura enquanto altura de dossel se mostrou mais indicada para estimar os parâmetros culturais quando as plantas já recobriam as entrelinhas (+0.6 m colmo), mostrando-se os sistemas sensores complementares quando o período de fertilização for mais amplo na fase inicial da cultura.