Control of integrated unit operations

As a thermal separation method, distillation is one of the most important technologies in the chemical industry. Given its importance, it is no surprise that increasing efforts have been made in reducing its energy inefficiencies. A great deal of research is focused in the design and optimization of the Divided-Wall Column. Its applications are still reduced due to distrust of its controllability. Previous references studied the decentralized control of DWC but still few papers deal about Model Predictive Control. In this work we present a decentralized control of both a DWC column along with its equivalent MPC schema.

Desarrollo de un Procedimiento Basado en Algoritmos de Optimización para el Dimensionado de Absorbedores Puntuales Aplicados a la Conversión de Energía Undimotriz

La energía transportada por el oleaje a través de los océanos (energía undimotriz) se enmarca dentro de las denominadas energías oceánicas. Su aprovechamiento para generar energía eléctrica (o ser aprovechada de alguna otra forma) es una idea reflejada ya hace más de dos siglos en una patente (1799). Desde entonces, y con especial intensidad desde los años 70, ha venido despertando el interés de instituciones ligadas al I+D+i y empresas del sector energético y tecnológico, debido principalmente a la magnitud del recurso disponible. Actualmente se puede considerar al sector en un estado precomercial, con un amplio rango de dispositivos y tecnologías en diferente grado de desarrollo en los que ninguno destaca sobre los otros (ni ha demostrado su viabilidad económica), y sin que se aprecie una tendencia a converger un único dispositivo (o un número reducido de ellos). El recurso energético que se está tratando de aprovechar, pese a compartir la característica de no-controlabilidad con otras fuentes de energía renovable como la eólica o la solar, presenta una variabilidad adicional. De esta manera, diferentes localizaciones, pese a poder presentar recursos de contenido energético similar, presentan oleajes de características muy diferentes en términos de alturas y periodos de oleaje, y en la dispersión estadística de estos valores. Esta variabilidad en el oleaje hace que cobre especial relevancia la adecuación de los dispositivos de aprovechamiento de energía undimotriz (WEC: Wave Energy Converter) a su localización, de cara a mejorar su viabilidad económica. Parece razonable suponer que, en un futuro, el proceso de diseño de un parque de generación undimotriz implique un rediseño (en base a una tecnología conocida) para cada proyecto de implantación en una nueva localización. El objetivo de esta tesis es plantear un procedimiento de dimensionado de una tecnología de aprovechamiento de la energía undimotriz concreta: los absorbedores puntuales. Dicha metodología de diseño se plantea como un problema de optimización matemático, el cual se resuelve utilizando un algoritmo de optimización bioinspirado: evolución diferencial. Este planteamiento permite automatizar la fase previa de dimensionado implementando la metodología en un código de programación. El proceso de diseño de un WEC es un problema de ingería complejo, por lo que no considera factible el planteamiento de un diseño completo mediante un único procedimiento de optimización matemático. En vez de eso, se platea el proceso de diseño en diferentes etapas, de manera que la metodología desarrollada en esta tesis se utilice para obtener las dimensiones básicas de una solución de referencia de WEC, la cual será utilizada como punto de partida para continuar con las etapas posteriores del proceso de diseño. La metodología de dimensionado previo presentada en esta tesis parte de unas condiciones de contorno de diseño definidas previamente, tales como: localización, características del sistema de generación de energía eléctrica (PTO: Power Take-Off), estrategia de extracción de energía eléctrica y concepto concreto de WEC). Utilizando un algoritmo de evolución diferencial multi-objetivo se obtiene un conjunto de soluciones factibles (de acuerdo con una ciertas restricciones técnicas y dimensionales) y óptimas (de acuerdo con una serie de funciones objetivo de pseudo-coste y pseudo-beneficio). Dicho conjunto de soluciones o dimensiones de WEC es utilizado como caso de referencia en las posteriores etapas de diseño. En el documento de la tesis se presentan dos versiones de dicha metodología con dos modelos diferentes de evaluación de las soluciones candidatas. Por un lado, se presenta un modelo en el dominio de la frecuencia que presenta importantes simplificaciones en cuanto al tratamiento del recurso del oleaje. Este procedimiento presenta una menor carga computacional pero una mayor incertidumbre en los resultados, la cual puede traducirse en trabajo adicional en las etapas posteriores del proceso de diseño. Sin embargo, el uso de esta metodología resulta conveniente para realizar análisis paramétricos previos de las condiciones de contorno, tales como la localización seleccionada. Por otro lado, la segunda metodología propuesta utiliza modelos en el domino estocástico, lo que aumenta la carga computacional, pero permite obtener resultados con menos incertidumbre e información estadística muy útil para el proceso de diseño. Por este motivo, esta metodología es más adecuada para su uso en un proceso de dimensionado completo de un WEC. La metodología desarrollada durante la tesis ha sido utilizada en un proyecto industrial de evaluación energética preliminar de una planta de energía undimotriz. En dicho proceso de evaluación, el método de dimensionado previo fue utilizado en una primera etapa, de cara a obtener un conjunto de soluciones factibles de acuerdo con una serie de restricciones técnicas básicas. La selección y refinamiento de la geometría de la solución geométrica de WEC propuesta fue realizada a posteriori (por otros participantes del proyecto) utilizando un modelo detallado en el dominio del tiempo y un modelo de evaluación económica del dispositivo. El uso de esta metodología puede ayudar a reducir las iteraciones manuales y a mejorar los resultados obtenidos en estas últimas etapas del proyecto. ABSTRACT The energy transported by ocean waves (wave energy) is framed within the so-called oceanic energies. Its use to generate electric energy (or desalinate ocean water, etc.) is an idea expressed first time in a patent two centuries ago (1799). Ever since, but specially since the 1970’s, this energy has become interesting for R&D institutions and companies related with the technological and energetic sectors mainly because of the magnitude of available energy. Nowadays the development of this technology can be considered to be in a pre-commercial stage, with a wide range of devices and technologies developed to different degrees but with none standing out nor economically viable. Nor do these technologies seem ready to converge to a single device (or a reduce number of devices). The energy resource to be exploited shares its non-controllability with other renewable energy sources such as wind and solar. However, wave energy presents an additional short-term variability due to its oscillatory nature. Thus, different locations may show waves with similar energy content but different characteristics such as wave height or wave period. This variability in ocean waves makes it very important that the devices for harnessing wave energy (WEC: Wave Energy Converter) fit closely to the characteristics of their location in order to improve their economic viability. It seems reasonable to assume that, in the future, the process of designing a wave power plant will involve a re-design (based on a well-known technology) for each implementation project in any new location. The objective of this PhD thesis is to propose a dimensioning method for a specific wave-energy-harnessing technology: point absorbers. This design methodology is presented as a mathematical optimization problem solved by using an optimization bio-inspired algorithm: differential evolution. This approach allows automating the preliminary dimensioning stage by implementing the methodology in programmed code. The design process of a WEC is a complex engineering problem, so the complete design is not feasible using a single mathematical optimization procedure. Instead, the design process is proposed in different stages, so the methodology developed in this thesis is used for the basic dimensions of a reference solution of the WEC, which would be used as a starting point for the later stages of the design process. The preliminary dimensioning methodology presented in this thesis starts from some previously defined boundary conditions such as: location, power take-off (PTO) characteristic, strategy of energy extraction and specific WEC technology. Using a differential multi-objective evolutionary algorithm produces a set of feasible solutions (according to certain technical and dimensional constraints) and optimal solutions (according to a set of pseudo-cost and pseudo-benefit objective functions). This set of solutions or WEC dimensions are used as a reference case in subsequent stages of design. In the document of this thesis, two versions of this methodology with two different models of evaluation of candidate solutions are presented. On the one hand, a model in the frequency domain that has significant simplifications in the treatment of the wave resource is presented. This method implies a lower computational load but increased uncertainty in the results, which may lead to additional work in the later stages of the design process. However, use of this methodology is useful in order to perform previous parametric analysis of boundary conditions such as the selected location. On the other hand, the second method uses stochastic models, increasing the computational load, but providing results with smaller uncertainty and very useful statistical information for the design process. Therefore, this method is more suitable to be used in a detail design process for full dimensioning of the WEC. The methodology developed throughout the thesis has been used in an industrial project for preliminary energetic assessment of a wave energy power plant. In this assessment process, the method of previous dimensioning was used in the first stage, in order to obtain a set of feasible solutions according to a set of basic technical constraints. The geometry of the WEC was refined and selected subsequently (by other project participants) using a detailed model in the time domain and a model of economic evaluation of the device. Using this methodology can help to reduce the number of design iterations and to improve the results obtained in the last stages of the project.

Social stress and the reactivation of latent herpes simplex virus type 1

Psychological stress is thought to contribute to reactivation of latent herpes simplex virus (HSV). Although several animal models have been developed in an effort to reproduce different pathogenic aspects of HSV keratitis or labialis, until now, no good animal model existed in which application of a psychological laboratory stressor results in reliable reactivation of the virus. Reported herein, disruption of the social hierarchy within colonies of mice increased aggression among cohorts, activated the hypothalamic-pituitary-adrenal axis, and caused reactivation of latent HSV type 1 in greater than 40% of latently infected animals. However, activation of the hypothalamic-pituitary-adrenal axis using restraint stress did not activate the latent virus. Thus, the use of social stress in mice provides a good model in which to investigate the neuroendocrine mechanisms that underlie behaviorally mediated reactivation of latent herpesviruses.

Repeated, but not acute, stress suppresses inflammatory plasma extravasation

Clinical findings suggest that inflammatory disease symptoms are aggravated by ongoing, repeated stress, but not by acute stress. We hypothesized that, compared with single acute stressors, chronic repeated stress may engage different physiological mechanisms that exert qualitatively different effects on the inflammatory response. Because inhibition of plasma extravasation, a critical component of the inflammatory response, has been associated with increased disease severity in experimental arthritis, we tested for a potential repeated stress-induced inhibition of plasma extravasation. Repeated, but not single, exposures to restraint stress produced a profound inhibition of bradykinin-induced synovial plasma extravasation in the rat. Experiments examining the mechanism of inhibition showed that the effect of repeated stress was blocked by adrenalectomy, but not by adrenal medullae denervation, suggesting that the adrenal cortex mediates this effect. Consistent with known effects of stress and with mediation by the adrenal cortex, restraint stress evoked repeated transient elevations of plasma corticosterone levels. This elevated corticosterone was necessary and sufficient to produce inhibition of plasma extravasation because the stress-induced inhibition was blocked by preventing corticosterone synthesis and, conversely, induction of repeated transient elevations in plasma corticosterone levels mimicked the effects of repeated stress. These data suggest that repetition of a mild stressor can induce changes in the physiological state of the animal that enable a previously innocuous stressor to inhibit the inflammatory response. These findings provide a potential explanation for the clinical association between repeated stress and aggravation of inflammatory disease symptoms and provide a model for study of the biological mechanisms underlying the stress-induced aggravation of chronic inflammatory diseases.

Temporary Disruption of the Plasma Membrane Is Required for c-fos Expression in Response to Mechanical Stress

Mechanically stressed cells display increased levels of fos message and protein. Although the intracellular signaling pathways responsible for FOS induction have been extensively characterized, we still do not understand the nature of the primary cell mechanotransduction event responsible for converting an externally acting mechanical stressor into an intracellular signal cascade. We now report that plasma membrane disruption (PMD) is quantitatively correlated on a cell-by-cell basis with fos protein levels expressed in mechanically injured monolayers. When the population of PMD-affected cells in injured monolayers was selectively prevented from responding to the injury, the fos response was completely ablated, demonstrating that PMD is a requisite event. This PMD-dependent expression of fos protein did not require cell exposure to cues inherent in release from cell–cell contact inhibition or presented by denuded substratum, because it also occurred in subconfluent monolayers. Fos expression also could not be explained by factors released through PMD, because cell injury conditioned medium failed to elicit fos expression. Translocation of the transcription factor NF-κB into the nucleus may also be regulated by PMD, based on a quantitative correlation similar to that found with fos. We propose that PMD, by allowing a flux of normally impermeant molecules across the plasma membrane, mediates a previously unrecognized form of cell mechanotransduction. PMD may thereby lead to cell growth or hypertrophy responses such as those that are present normally in mechanically stressed skeletal muscle and pathologically in the cardiovascular system.

Experimental diabetes in rats causes hippocampal dendritic and synaptic reorganization and increased glucocorticoid reactivity to stress

We report that 9 d of uncontrolled experimental diabetes induced by streptozotocin (STZ) in rats is an endogenous chronic stressor that produces retraction and simplification of apical dendrites of hippocampal CA3 pyramidal neurons, an effect also observed in nondiabetic rats after 21 d of repeated restraint stress or chronic corticosterone (Cort) treatment. Diabetes also induces morphological changes in the presynaptic mossy fiber terminals (MFT) that form excitatory synaptic contacts with the proximal CA3 apical dendrites. One effect, synaptic vesicle depletion, occurs in diabetes as well as after repeated stress and Cort treatment. However, diabetes produced other MFT structural changes that differ qualitatively and quantitatively from other treatments. Furthermore, whereas 7 d of repeated stress was insufficient to produce dendritic or synaptic remodeling in nondiabetic rats, it potentiated both dendritic atrophy and MFT synaptic vesicle depletion in STZ rats. These changes occurred in concert with adrenal hypertrophy and elevated basal Cort release as well as hypersensitivity and defective shutoff of Cort secretion after stress. Thus, as an endogenous stressor, STZ diabetes not only accelerates the effects of exogenous stress to alter hippocampal morphology; it also produces structural changes that overlap only partially with those produced by stress and Cort in the nondiabetic state.

A feedback-controlled ensemble model of the stress-responsive hypothalamo-pituitary-adrenal axis

The present work develops and implements a biomathematical statement of how reciprocal connectivity drives stress-adaptive homeostasis in the corticotropic (hypothalamo-pituitary-adrenal) axis. In initial analyses with this interactive construct, we test six specific a priori hypotheses of mechanisms linking circadian (24-h) rhythmicity to pulsatile secretory output. This formulation offers a dynamic framework for later statistical estimation of unobserved in vivo neurohormone secretion and within-axis, dose-responsive interfaces in health and disease. Explication of the core dynamics of the stress-responsive corticotropic axis based on secure physiological precepts should help to unveil new biomedical hypotheses of stressor-specific system failure.

Chronic stress alters the immune response to influenza virus vaccine in older adults.

To determine whether a chronic stressor (caregiving for a spouse with a progressive dementia) is associated with an impaired immune response to influenza virus vaccination, we compared 32 caregivers' vaccine responses with those of 32 sex-, age-, and socioeconomically matched control subjects. Caregivers showed a poorer antibody response following vaccination relative to control subjects as assessed by two independent methods, ELISA and hemagglutination inhibition. Caregivers also had lower levels of in vitro virus-specific-induced interleukin 2 levels and interleukin 1beta; interleukin 6 did not differ between groups. These data demonstrate that down-regulation of the immune response to influenza virus vaccination is associated with a chronic stressor in the elderly. These results could have implications for vulnerability to infection among older adults.

Distinct mechanisms underlie activation of hypothalamic neurosecretory neurons and their medullary catecholaminergic afferents in categorically different stress paradigms.

Intermittent electrical footshock induces c-fos expression in parvocellular neurosecretory neurons expressing corticotropin-releasing factor and in other visceromotor cell types of the paraventricular hypothalamic nucleus (PVH). Since catecholaminergic neurons of the nucleus of the solitary tract and ventrolateral medulla make up the dominant loci of footshock-responsive cells that project to the PVH, these were evaluated as candidate afferent mediators of hypothalamic neuroendocrine responses. Rats bearing discrete unilateral transections of this projection system were exposed to a single 30-min footshock session and sacrificed 2 hr later. Despite depletion of the aminergic innervation on the ipsilateral side, shock-induced up-regulation of Fos protein and corticotropin-releasing factor mRNA were comparable in strength and distribution in the PVH on both sides of the brain. This lesion did, however, result in a substantial reduction of Fos expression in medullary aminergic neurons on the ipsilateral side. These results contrast diametrically with those obtained in a systemic cytokine (interleukin 1) challenge paradigm, where similar cuts ablated the Fos response in the ipsilateral PVH but left intact the induction seen in the ipsilateral medulla. We conclude that (i) footshock-induced activation of medullary aminergic neurons is a secondary consequence of stress, mediated via a descending projection transected by our ablation, (ii) stress-induced activation of medullary aminergic neurons is not necessarily predictive of an involvement of these cell groups in driving hypothalamic visceromotor responses to a given stressor, and (iii) despite striking similarities in the complement of hypothalamic effector neurons and their afferents that may be activated by stresses of different types, distinct mechanisms may underlie adaptive hypothalamic responses in each.

Persistent elevations of cerebrospinal fluid concentrations of corticotropin-releasing factor in adult nonhuman primates exposed to early-life stressors: implications for the pathophysiology of mood and anxiety disorders.

There is increasing evidence for an important role of adverse early experience on the development of major psychiatric disorders in adulthood. Corticotropin-releasing factor (CRF), an endogenous neuropeptide, is the primary physiological regulator of the mammalian stress response. Grown nonhuman primates who were exposed as infants to adverse early rearing conditions were studied to determine if long-term alterations of CRF neuronal systems had occurred following the early stressor. In comparison to monkeys reared by mothers foraging under predictable conditions, infant monkeys raised by mothers foraging under unpredictable conditions exhibited persistently elevated cerebrospinal fluid (CSF) concentrations of CRF. Because hyperactivity of CRF-releasing neurons has been implicated in the pathophysiology of certain human affective and anxiety disorders, the present finding provides a potential neurobiological mechanism by which early-life stressors may contribute to adult psychopathology.

Sentidos de família construídos por profissionais de saúde na estratégia de saúde da família

Na construção de políticas sociais atribuiu-se um papel central à família na proteção social e no cuidado com os seus membros. Na saúde, a família assume essa centralidade na Estratégia de Saúde da Família (ESF), sendo compreendida como objeto da atenção em saúde. Essa centralidade se deu a partir de uma pretensão de mudança no modelo assistencial que visasse a integralidade do cuidado e um olhar para as condições de vida como fundamentais no processo saúde-doença. Tais transformações nos sentidos e práticas de saúde têm sido desafiadoras. A partir da perspectiva Construcionista Social, que orienta esse estudo, compreendemos que os sentidos são construídos nas interações entre as pessoas e que esses configuram práticas sociais. Diante deste quadro de desafios na ESF e a partir da perspectiva adotada, temos como objetivo compreender os sentidos produzidos por profissionais de equipes de saúde sobre famílias em contextos de reuniões de discussão de família/caso na ESF, buscando analisar como esses configuram a produção de práticas de cuidado e também como se dá a dinâmica de construção desses sentidos a partir das negociações entre os participantes. A constituição do corpus foi feita a partir da observação e registros em áudio de 16 reuniões de duas equipes de saúde da família, contando com 26 participantes, dentre eles profissionais e estagiários de diferentes especialidades. A análise foi feita a partir da perspectiva das práticas discursivas, com os seguintes passos: 1) transcrição do material; 2) leitura intensiva e organização do material; 3) construção de sentidos sobre a família, e análise dos repertórios interpretativos, discursos usados, e implicações para ação; e 4) narrativa ilustrativa da dinâmica dos sentidos. Os sentidos construídos na análise foram: a) Família como pessoas que moram juntas: os repertórios usados descreviam os modos de ser família a partir do ambiente em que ela vive, entendendo a família como informante e cuidadora dos seus membros; b) Família como responsável pelo cuidado: repertórios de família como aquela que dá suporte aos seus membros e é responsável por eles; e, por vezes, está sobrecarregada com esses cuidados; c) Família como problema: repertórios que configuravam a família como aquela que é responsável pelo problema de saúde dos seus membros, como aquela que funciona como um estressor para eles ou como aquela que está em situação de risco; e d) Família como rede de relações, sentido que foi usado, mais comumente, em conversas sobre casos complexos, com discussões voltadas para configurações, estruturas e dinâmicas familiares. A partir da análise do processo de discussão da equipe em torno de um \"caso\", foi possível ilustrar o dinamismo desses sentidos nas conversas e como esses são negociados a todo momento. A análise nos permite considerar que há esforços dos profissionais em voltar a atenção do cuidado para a família, porém ainda são comuns práticas centradas no indivíduo e pouco pautadas no contexto e nas condições de vida das famílias. Compreendemos que dar visibilidade a esses diferentes sentidos e seu uso permite reflexões sobre como cada forma de descrever as famílias possibilita a construção de práticas distintas, o que pode contribuir para uma maior reflexão dos profissionais de saúde sobre sua prática cotidiana (Apoio Capes e Fapesp- 2014/08618-6).

Parenting influences on depression: A moderated mediated model

Little is known about the developmental processes through which parenting factors may influence clinical depression among youth. This study investigated whether parenting influences the onset of clinical depression through the mediating mechanism of negative attributional style, particularly under conditions of high stress, in a community sample of children and adolescents (N = 289). Results supported a moderated mediation model in which low levels of observed parent positive regard and sensitivity to distress during a youth stressor task were indirectly associated with an increased likelihood of experiencing an episode of depression over an18 month period, through the mediating influence of youth negative attributional style, but only for youth who also experienced a high number of peer stressors. These findings elucidate mechanisms through which parenting may contribute to risk for depression during the transition into and across adolescence.

Tailoring the surface chemistry of zeolite templated carbon by electrochemical methods

One option to optimize carbon materials for supercapacitor applications is the generation of surface functional groups that contribute to the pseudocapacitance without losing the designed physical properties. This requires suitable functionalization techniques able to selectively introduce a given amount of electroactive oxygen groups. In this work, the influence of the chemical and electrochemical oxidation methods, on the chemical and physical properties of a zeolite templated carbon (ZTC), as a model carbon material, have been studied and compared. Although both oxidation methods generally produce a loss of the original ZTC physical properties with increasing amount of oxidation, the electrochemical method shows much better controllability and, unlike chemical treatments, enables the generation of a large number of oxygen groups (O = 11000- 3300 μmol/g), with a higher proportion of active functionalities, while retaining a high surface area (ranging between 1900-3500 m2/g), a high microporosity and an ordered 3-D structure.

Electrochemical generation of oxygen-containing groups in an ordered microporous zeolite-templated carbon

Zeolite templated carbon (ZTC) was electrochemically oxidized under various conditions, and its chemistry and structural evolution were compared to those produced by conventional chemical oxidation. In both oxidation methods, a general loss of the original structure regularity and high surface area was observed with increasing amount of oxidation. However, the electrochemical method showed much better controllability and enabled the generation of a large number of oxygen functional groups while retaining the original structure of the ZTC. Unlike chemical treatments, highly microporous carbons with an ordered 3-D structure, high surface area (ranging between 1900 and 3500 m2/g) and a large number of oxygen groups (O = 11,000–3300 μmol/g), have been prepared by the electrochemical method. Some insights into the electrooxidation mechanism of carbon materials are proposed from the obtained polarization curves, using ZTC as a model carbon material.

Founder, Academic, or Employee? A Nuanced Study of Career Choice Intentions

We add novel insights to the debate about why individuals choose to start their own firm by comparing entrepreneurial intentions to the intentions to work at a university as an academic and to be employed in a private firm. To model this more complex set of career choices, we examine novel multiplicative aspects of the theory of planned behavior (TPB) and test our hypotheses on survey data of 15,866 students from 13 European countries. Multinomial logistic regression analyses reveal how the different TPB elements influence career preferences and demonstrate the moderating effects of perceived controllability and desirability.