Analysis of the particle swarm algorithm in the optimization of a three-phase slurry catalytic reactor

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)The Particle Swarm Optimization (PSO) method was employed to optimize an industrial chemical process characterized by being difficult to be optimized by conventional deterministic methods. The chemical process is a three phase catalytic slurry reactor (tubular geometry) in which the reaction of the hydrogenation of o-cresol producing 2-methyl-cyclohexanol is carried out. The optimization problem was formulated considering as input variables the operating conditions of the reactor and as objective function the maximization of productivity, subject to the environmental constraint of conversion. The process was represented by a multivariable non-linear rigorous mathematical model and in order to solve the optimization problem, the performance of the PSO algorithm was evaluated considering four sets of parameters values suggested by the literature. PSO demonstrated to be efficient and robust to solve the constrained optimization problem, independently of the values of the PSO parameters. The solution of the rigorous mathematical model of the reactor was associated with a high computational burden, and although the PSO algorithm presented high rate of convergence, the attempt to make possible the optimization in a timeframe suitable to real time applications failed because the algorithm lost robustness (fraction of the number of runs the algorithm reached the optimization goal) when run with a reduced number of function evaluations. Therefore, if this type of application is desired, simplified mathematical models with fast and simple numerical methods must be preferred. (C) 2011 Elsevier Ltd. All rights reserved.351227412749Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Optimization of a Three-Phase Catalytic Slurry Reactor Using Reduced Statistical Models

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)The main contribution of this work is to propose the use of a statistical procedure to generate simplified models from a detailed deterministic one for Real Time Optimization. Such models are also used as a tool to map the optimal and feasible region. These simplified models are useful in online optimization coupled to control implementations, since detailed rigorous models may demand time and high computational burden for their solution, which hampers the success of online purposes. In order to illustrate the application of the procedure, a three-phase catalytic reactor was considered. A dynamic heterogeneous mathematical model formulation of the o-cresol hydrogenation reaction was used to simulate the reactor steady-state response to different inlet conditions. The proposed statistical procedure (factorial design) generated simplified models for the reactor exit temperature and the reactant conversion, two useful pieces of process information. The use of these models in an optimization problem is then presented as an illustration of their application in an online real time optimization in a two-layer fashion. The simplified models turn possible the identification of the range of optimal solutions as well as the mapping of the region of optimal solutions very quickly compared to the use of full models, allowing the system to be flexibly operated at high level of performance.o TEXTO COMPLETO DESTE ARTIGO, ESTARÁ DISPONÍVEL À PARTIR DE AGOSTO DE 2015.8Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Effective tooth-bleaching protocols capable of reducing H2O2 diffusion through enamel and dentine

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Objectives: To evaluate the effects of experimental protocols on bleaching effectiveness and hydrogen peroxide (HP) diffusion through enamel and dentine. Methods: Enamel/dentine discs were subjected to six bleaching sessions, consisting of 1 or 3 applications of 17.5% or 35%-HP gel for 5/15 min, or 37% carbamide peroxide (CP) gel for 10/20 min. Discs undergoing the regular protocol (35%-HP; 3 x 15 min) constituted the positive control group. Colour change (Delta E) was assessed (CIE L*a*b* system) after each session. HP diffusion was quantified (sessions 1, 3, and 6) in enamel/dentine discs adapted to artificial pulp chambers. Data were analysed by Pillai's Trace and Bonferroni test, or by one-way ANOVA and SNK/Tamhane's test (alpha = 5%). Results: All tooth-bleaching protocols significantly increased the Delta E values. A reduction in HP diffusion and no significant difference in Delta E compared with the positive control were observed for the following bleaching protocols: 17.5%-HP 3 x 15 min, at the 4th session; and 35%-HP 1 x 15 and 3 x 5 min, at the 5th session. HP diffusion in the 37%-CP 3 x 20 min bleaching protocol was statistically similar to that in the positive control. The other experimental bleaching protocols significantly decreased HP diffusion through enamel/dentine discs, but the Delta E values were statistically lower than those observed in the positive control, in all sessions. Conclusion: Shortening the contact time of a 35%-HP gel or reducing its concentration produces gradual tooth colour change and reduced HP diffusion through enamel and dentine. Clinical significance: A reduction in HP concentration, from 35% to 17.5%, in a bleaching gel or shortening its application time on enamel provides a significant tooth-bleaching improvement associated with decreased HP diffusion across hard dental tissues. Therefore, these protocols may be an interesting alternative to be tested in the clinical situation. (C) 2013 Elsevier Ltd. All rights reserved.423351358Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)FAPESP [2011/12938-8, 2011/09385-7]CNPq [301029/2010-1

Evaluation of control algorithms for three-phase hydrogenation catalytic reactor

The present work deals with the proposition and evaluation of easy to implement control structures for a hydrogenation industrial size reactor. The used mathematical model formulation is a detailed deterministic and previously validated one, which was made focusing on the hydrogenation reaction of o-cresol to obtain the 2-methyl-cyclohexanol, in the presence of a Ni/SiO2 catalyst. A simplified model, generated through factorial design statistical tool, is also used for stationary states predictions, providing very quick solution, suitable for on-line applications. Five different control structures, based on the feedback and feedforward classic structures and on combinations of them, are evaluated both concerning to the ability of the controller to maintain (regulatory control) or to change the controlled variable to the new set-point (servo control) in a reasonable action time. The study shows that, in the analyzed operation range, the combined structure is the best one to be used for this reactor, both for the servo and regulatory control problems. The calculation of control actions is significantly reduced by the use of simplified models. However, since an offset is present in the regulatory problem when the simplified model is used, this model is not suggested to be used in the regulatory problem. (C) 2008 Elsevier B.V.. All rights reserved.1414169925026

Experiência existencial de mães de crianças hospitalizadas em Unidade de Terapia Intensiva Pediátrica Experiencia existencial de madres de niños hospitalizados en Unidades de Terapia Intensiva Pediátrica Existetial experienc of mothers of hospitalized children in intensive pediatric care unit

Este estudo tem como objetivo compreender a experiência existencial de mães de crianças hospitalizadas em Unidade de Terapia Intensiva Pediátrica (UTIP). Trata-se de uma pesquisa de natureza qualitativa, consubstanciada na Teoria Humanística de Enfermagem. O cenário da investigação foi uma UTIP de um hospital público. Participaram do trabalho cinco mães de crianças hospitalizadas na referida unidade. Os dados foram analisados com base nas cinco fases da Enfermagem Fenomenológica. A partir dos discursos expressos durante a coleta de dados, emergiram as seguintes temáticas: a relação vivenciada entre as mães e os profissionais de enfermagem no momento da admissão e ao longo da hospitalização da criança na UTIP; e mães vivenciando sentimentos de medo, desespero e solidão diante do adoecimento do filho. O presente estudo ressalta a complexidade de que se reveste uma abordagem centrada nas genitoras e subsidia um novo olhar no âmbito da assistência, do ensino e da pesquisa em enfermagem.<br>Este estudio tiene como objetivo comprender la experiencia existencial de madres de niños hospitalizados en Unidades de Terapia Intensiva Pediátrica (UTIP). Se trata de una investigación de naturaleza cualitativa basada en la Teoría Humanística de Enfermería. El escenario de la investigación fue una UTIP de un hospital público. Participaron del trabajo cinco madres de niños hospitalizados en la referida unidad. Los datos fueron analizados con base en las cinco fases de la Enfermería Fenomenológica. A partir de los discursos expresados durante la recolección de datos emergieron las siguientes temáticas: la relación experimentada entre las madres y los profesionales de enfermería en el momento de la admisión y a lo largo de la hospitalización del niño en la UTIP; madres experimentando sentimientos de miedo, desesperación y soledad delante de la enfermedad del hijo. El presente estudio resalta la complejidad de que se reviste un abordaje centrado en las genitoras y muestra una nueva perspectiva en el ámbito de la asistencia, de la enseñanza y de la investigación en enfermería.<br>This study has the objective of understanding the existential experience of mothers of children hospitalized in an Intensive Pediatric Care Unit (IPCU). It is a qualitative-based research grounded on the humanistic nursing theory. The investigation scenario was the IPCU of a public hospital. Five mothers of children who were hospitalized in the referred unit participated in the investigation. Data were analyzed from the standpoint of the five phases of the phenomenological nursing. The following issues emerged from the collected statements: the relationship between mothers and nursing professionals at the moment of admission and throughout the child's hospitalization period in the IPCU; and mothers who experience fear, despair and loneliness in face of the child's disease. The present study highlights the complexity of a mother-centered approach and subsidizes a new look at the field of the care, teaching and nursing research