Ricardo de Araújo Kalid

A PSO-based optimal tuning strategy for constrained multivariable predictive controllers with model uncertainty

This paper describes the development of a method to optimally tune constrained MPC algorithms with model uncertainty. The proposed method is formulated by using the worst-case control scenario, which is characterized by the Morari resiliency index and the condition number, and a given nonlinear multi-objective performance criterion. The resulting constrained mixed-integer nonlinear optimization problem is solved on the basis of a modified version of the particle swarm optimization technique, because of its effectiveness in dealing with this kind of problem. The performance of this PSO-based tuning method is evaluated through its application to the well-known Shell heavy oil fractionator process.

Fuzzy control of a nylon polymerization semi-batch reactor

Batch and semi-batch polymerization reactors with specified trajectories for certain process variables present challenging control problems. This work reports, results and procedures related to the application of PI (proportional and integral) fuzzy control in a semi-batch reactor for the production of nylon 6. Closed loop simulation results were based on a phenomenological model adjusted for a commercial reactor and they attest to the potential benefits and versatility of the use of PI fuzzy control in polymerization systems.

Collection of benchmark test problems for data reconciliation and gross error detection and identification

Abstract In an industrial scenario, one can find measured data that do not satisfy the mass and energy laws of conservation. This problem can be approached by applying data reconciliation (DR) and gross error detection and identification (GEDI) techniques, however, authors generally validate their methods using a reduced set of problems, restricting the application of the proposed methods to them. The objective of this work is to present a collection of benchmark problems for DR and GEDI to help the evaluation of these methods in different types of flowsheets. First, challenges issues related with DR and GED are presented with examples. Then, a general overview of the benchmark collection set is presented. In conclusion, it can be observed that this challenging research area needs a common problem set for validating DR and GEDI and this paper fills this gap, helping the validation of the methods.

Um modelo para o dimensionamento do corpo docente para o apoio à tomada de decisão no planejamento de instituições de ensino superior

Este trabalho propoe, desenvolve e aplica um modelo para o dimensionamento do corpo docente de unidades universitarias (departamentos, faculdades, escolas, institutos ou ate mesmo a universidade como um todo) e para o projeto da composicao de regime de trabalho otima desse corpo docente. A importância, contribuicao e oportunismo contemporâneo do trabalho se justificam especialmente em face da nova lei do professor-equivalente. O modelo contempla todas as atividades pertinentes a pratica docente universitaria (ensino de graduacao e pos-graduacao, pesquisa e orientacao, extensao, gestao e capacitacao) e, embora talhado especialmente para instituicoes federais de ensino superior (IFES), pode ser facilmente adequado para sua utilizacao em IES (instituicoes de ensino superior) de outras esferas governamentais e mesmo em IES comunitarias, confessionais ou privadas. Alem disso, o modelo e complementar e nao concorrente aos indicadores estabelecidos pelo Reuni (Programa de Apoio a Planos de Reestruturacao e Expansao das Universidades Federais), podendo ser considerado uma ferramenta de projeto de unidades universitarias, enquanto os segundos podem ser considerados como instrumentos de acompanhamento da operacao dessas unidades. O modelo e bastante generico, permitindo sua ampla aplicacao em diversos tipos de unidades universitarias, e alguns dos seus parâmetros podem ser ajustados a fim de satisfazer metas e politicas especificas dessas unidades. A aplicacao do modelo desenvolvido ao estudo de caso de um departamento mostra a sua consistencia e utilidade, inclusive como poderoso instrumento de apoio a tomada de decisao no planejamento e na gestao de recursos docentes em IES.

Water and Wastewater Management in a Petrochemical Raw Material Industry

Abstract Based on cleaner production concepts, a methodology for water use minimization has been developed by the Clean Technology Network of Bahia at one of the largest industrial complex in Latin America, in Camacari, Bahia, Brazil. Here we present the methodological tools and results of the water and wastewater minimization program at a petrochemical plant operated by Braskems Raw Material Unit (UNIB) at this complex. The set of tools used includes reconciled aqueous stream balances, database of aqueous streams, definition and analysis of water and wastewater indicators, as well as regional analysis in a search for more environmentally friendly water sources. Water mass balances had to be built with assumed values as poor measurement or rather lack of water measurement is a constant inside the industrial complex. Because of this, the proposed indicators had to be analyzed with caution. The studies have identified the possibility of recovering about 1,500 m 3 /h of the overall 5,700 m 3 /h water consumed by the industrial complex at the moment. The effluent flow rate has been reduced by 250 m 3 /h since 2002. Process variability was found to be an important cause of both effluent generation in total flow rate and its continuity.

Handy method to estimate uncertainty of temperature measurement by infrared thermography

Abstract. Temperature measurement by infrared thermography is a technique that is widely used in predictive maintenance to detect faults. The uncertainty involved in measuring temperature by thermography is not only due to the imager, but also due to the measurements and estimates made by the user: emissivity of the inspected object, distance, temperature, and relative humidity of the propagation medium, temperature of objects located in the ambient, and the imager itself. This measurement uncertainty should be available for the thermographer to be able to make a more accurate diagnosis. The methods available in the literature to estimate the uncertainty of measured temperature usually require information nonaccessible to the regular thermographer. This paper proposes a method for calculating the uncertainty of temperature that requires only data available to the thermographer. This method is useful under usual conditions in predictive maintenance—short distance (7.5 to 14 μm) thermal imagers, no fog or rain, among others. It provides results similar to methods that use models that are not available or reserved by the manufacturers of imagers. The results indicate that not all sources of uncertainty are relevant in measurement uncertainty. However, the total uncertainty can be so high that it may lead to misdiagnosis.

COMPARAÇÃO ENTRE OS MÉTODOS LINEAR E NÃO LINEAR PARA A AVALIAÇÃO DA INCERTEZA DE MEDIÇÃO

The main method recognized by the metrologists for the evaluation of measurement uncertainty is de facto the Guide to the Expression of Uncertainty in Measurement (ISO Guide). Due to some limitations of the proposed method by ISO Guide however, ISO has developed a supplementary method for evaluating the measurement uncertainty based on the propagation of probability density functions using the Monte Carlo method (ISO-S1). The present paper discusses these methods for the quantification of measurement uncertainty. We review the literature, in particular the main papers presenting these modern approaches. We also discuss the merits and the limitations of the ISO Guide and ISO-S1 approaches. Furthermore, a comparative study between these two methods was carried out in two case studies. The obtained results show that it is necessary to evaluate the influence of the degree of non linearity in order to estimate the measurement uncertainty before either method is chosen

Energy Efficiency in an Industrial Wet Cooling Tower Through Improved Control

Abstract Cooling towers are too much used in process plants in order to allow heat removal from the process to the atmosphere. These pieces of equipment are designed for achieve the maximum performance at design conditions. However, under other conditions such as lower heat load and lower wet bulb temperature, which frequently occur during plant operation, there is an excess of cooling capacity which is not used. This paper presents an open-loop analysis of an industrial wet cooling tower and proposes a closed-loop strategy in order to control two indexes of performance (efficiency and effectiveness). The closed-loop results suggest the possibility of a sensible improvement in the eco-efficiency of this piece of equipment thorough an expressive reduction in its energy consumption, without dropping of performance regarding the satisfaction of the thermal requirements of the process.

A fuzzy modeling approach to optimize control and decision making in conflict management in air traffic control

Abstract The intensification of air traffic worldwide has increased the complexity of the control operations and the search for alternatives to support decision-making in this sector. This paper presents two fuzzy models, structured according to Mamdani, for the control of conflict in the air traffic route, based on the manipulation of the longitudinal speed of the aircraft, considering the rules set out by the International Civil Aviation Organization (ICAO). Both fuzzy models work jointly following a dynamic approach. The first model proposes a metric to quantify the longitudinal conflict levels between two aircraft in the same direction (located in the same airway) and the second model provides the longitudinal acceleration of the aircraft based on the level of conflict detected. The results show that the proposed approach is able to detect and remove longitudinal conflicts in advance, providing a potential tool to support decision-making and to improve the safety and the optimized use of airspace.

CONSTRUÇÃO DE UM BALANÇO HÍDRICO RECONCILIADO EM PLANTA DE METANOL COM EXIGUIDADE DE INFORMAÇÃO

As previsões incertas em relação à oferta e demanda de água no futuro, juntamente com a cobrança de captação e liberação de efluentes nas bacias hidrográficas brasileiras, vem forçando o setor industrial a adotarem estratégias de melhor gestão dos seus recursos hídricos. O balanço hídrico reconciliado é uma ferramenta que permite mapear as correntes aquosas para um melhor conhecimento do fluxo de água em uma unidade industrial. Entretanto, no geral, os processos de produção carecem de medições de água para a sua construção. O conceito de qualidade de informação (QI) foi criado pela Rede de Tecnologia Limpas, da Universidade Federal da Bahia, com intuito de permitir utilizar diversas formas para obtenção de dados, mas levando em consideração as incertezas associadas pela falta de informação precisa das vazões de entrada e saída. O objetivo deste artigo é criar XXXVII ENCONTRO NACIONAL DE ENGENHARIA DE PRODUCAO “A Engenharia de Produção e as novas tecnologias produtivas: indústria 4.0, manufatura aditiva e outras abordagens avançadas de produção”