Modelagem e simulação da solubilização da parafina em tubos circulares e em regime laminar

O óleo produzido nos novos campos de petróleo está cada vez mais parafínico e viscoso, com isso, à medida que o óleo é escoado, parafinas são depositadas sobre as paredes internas do tubo, e ao longo do tempo, tendem a reduzir drasticamente a área transversal ao escoamento. Visando estudar o processo de solubilização da parafina em dutos, esse trabalho objetiva desenvolver modelos matemáticos que represente o processo, com base nos fenômenos envolvidos no mesmo tais como transferência de massa, transferência de energia e equilíbrio sólido-líquido, implementando-os em um ambiente de desenvolvimento VBA (Visual Basic) for Excel ®. O presente trabalho foi realizado em quatro etapas: i) modelagem dos fenômenos de transferência de calor e massa, ii) modelagem da rotina dos coeficientes de atividade através do modelo UNIFAC e modelagem do sistema de equilíbrio sólido-líquido; iii) modelagem matemática do processo de solubilização e cálculo da espessura da parafina ao longo do tempo; iv) implementação dos modelos em um ambiente de desenvolvimento VBA for Excel® e criação de um simulador com uma interface gráfica, para simular o processo de solubilização da parafina depositada em dutos e sua otimização. O simulador conseguiu produzir soluções bastante adequadas, mantendo continuidade das equações diferenciáveis do balanço de energia e de massa, com uma interpretação física viável, sem a presença de dissipação de oscilações nos perfis de temperatura e massa. Além disso, esse simulador visa permitir a simulação nas diversas condições de escoamento, bem como compreender a importância das variáveis (vazão, temperatura de entrada, temperatura externa, cadeia carbônica do solvente). Através dos resultados foram possíveis verificar os perfis de temperatura, fração molar e o de solubilização

Recuperação e purificação de quitosanases usando adsorção em leito expandido com streamline DEAE com modelagem e simulação usando redes neurais

Expanded Bed Adsorption (EBA) is an integrative process that combines concepts of chromatography and fluidization of solids. The many parameters involved and their synergistic effects complicate the optimization of the process. Fortunately, some mathematical tools have been developed in order to guide the investigation of the EBA system. In this work the application of experimental design, phenomenological modeling and artificial neural networks (ANN) in understanding chitosanases adsorption on ion exchange resin Streamline® DEAE have been investigated. The strain Paenibacillus ehimensis NRRL B-23118 was used for chitosanase production. EBA experiments were carried out using a column of 2.6 cm inner diameter with 30.0 cm in height that was coupled to a peristaltic pump. At the bottom of the column there was a distributor of glass beads having a height of 3.0 cm. Assays for residence time distribution (RTD) revelead a high degree of mixing, however, the Richardson-Zaki coefficients showed that the column was on the threshold of stability. Isotherm models fitted the adsorption equilibrium data in the presence of lyotropic salts. The results of experiment design indicated that the ionic strength and superficial velocity are important to the recovery and purity of chitosanases. The molecular mass of the two chitosanases were approximately 23 kDa and 52 kDa as estimated by SDS-PAGE. The phenomenological modeling was aimed to describe the operations in batch and column chromatography. The simulations were performed in Microsoft Visual Studio. The kinetic rate constant model set to kinetic curves efficiently under conditions of initial enzyme activity 0.232, 0.142 e 0.079 UA/mL. The simulated breakthrough curves showed some differences with experimental data, especially regarding the slope. Sensitivity tests of the model on the surface velocity, axial dispersion and initial concentration showed agreement with the literature. The neural network was constructed in MATLAB and Neural Network Toolbox. The cross-validation was used to improve the ability of generalization. The parameters of ANN were improved to obtain the settings 6-6 (enzyme activity) and 9-6 (total protein), as well as tansig transfer function and Levenberg-Marquardt training algorithm. The neural Carlos Eduardo de Araújo Padilha dezembro/2013 9 networks simulations, including all the steps of cycle, showed good agreement with experimental data, with a correlation coefficient of approximately 0.974. The effects of input variables on profiles of the stages of loading, washing and elution were consistent with the literature

Desenvolvimento de sorvete probiótico a base de leite de cabra: estudo da formulação, características físico químicas, sensoriais e viabilidade das bactérias probióticas

This work targetet the caprine ice cream production added with probiotic bacteria Bifidobacterium animalis subsp. lactis. It is divided into two parts. In the first one, four caprine ice cream formulations were evaluated, in which it was used hydrogenated fat (F1 and F3) or fat substitute (F2 and F4) in two different flavors (F1 and F2, passion fruit, F3 and F4, guava). Statistical differences (p<0.05) were detected for their physical-chemical properties, mainly for total solids and fat, but no differences were observed for melting test results. When it went to sensory acceptance, all four ice cream formulations reached high acceptance indexes, mostly formulation F4, which was selected for further studies. In the second part, F4 formulation was prepared with the addition of probiotic bacteria Bifidobacterium animalis subsp. lactis. The growth kinetics was studied and it was observed that the cellular concentration peak was reached after four fermentation hours (10.14 log UFC/g). This time was selected for pre-fermentation procedure and posterior addition at ice cream syrup. In this part of the study, two experimental groups were evaluated: group G1, in which the probiotic addition occurred before the maturation step and group G2, which included a pre-fermentation step and probiotic addition after ice cream maturation. The physical-chemical properties of these two ice cream groups were similar, except for pH, which was higher for group G2 (p<0.05). G1 samples had superior melting rate (3.566 mL/min) and both groups presented microbiological and sanitary results in accordance to current Brazilian legislation. Also, G1 and G2 were considered sensory accepted due to their acceptance indexes higher than 70%. G1 and G2 sensory profiles were similar (p>0.05), and both ice cream samples exhibited high creaminess (6.76 to 6.91) and mouth melting sensation (6.53 to 6.67) scores, while low sandiness scores (0.85 to 0.86) were observed, positive characteristics for this kind of food product. During the first 24 hours after ice cream production, the population of B. animalis subsp. lactis decreased, reaching 7.15 e 6.92 log CFU/g for G1 and G2, respectively. Probiotic bacteria counts fluctuated in ice cream samples during the first 108 days at frozen storage, especially for G2 group. Decreased probiotic viability was observed for G1 samples during the first 35 days of frozen storage, mild variation between 35 and 63 days and stabilized counts were observed after this time. After 21 days at frozen storage, ice cream samples of G1 and G2 groups reached 1.2 x 109 and 1.3 x 109 CFU/portion, respectively. After 108 days under these storage conditions, the survival rate of B. animalis subsp. lactis was 94.26% and 81.10% for G1 and G2 samples, respectively. After simulation of gastroenteric conditions, G2 group reached 9.72 x 105 CFU/portion. Considering the current requirements of Brazilian legislation, which stipulates that functional foods must have minimum probiotic count between 108 and 109 CFU/portion and detectable probiotic bacteria after being submitted to gastroenteric conditions, it is concluded that the ice cream with the addition of Bifidobacterium animalis subsp. lactis made as shown in this work, can be considered as a dairy functional food

Eutrofização do Reservatório Cruzeta na bacia representativa do rio Seridó RN

Eutrophication has been listed as one of the main problems of water pollution on a global level. In the Brazilian semi-arid areas this problem takes even greater proportions due to characteristical water scarcity of the region. It is extremely important to the predictive eutrophication models development and to the reservoirs management in the semi-arid region, studies that promotes understanding of the mechanisms responsible for the expansion and control of algae blooms, essential for improving the water quality of these environments. The present study had as its main aims, evaluate the temporal pattern of trophic state, considering the influence of nutrients (N and P) and the light availability in the water column in the development of phytoplankton biomass, and perform the mathematical modelling of changes in phosphorus and chlorophyll a concentrations in the Cruzeta man-made lake located on Seridó, a typical semi-arid region of Rio Grande do Norte. To this, a fortnightly monitoring was performed in the reservoir in 05 stations over the months of March 2007 to May 2008. Were measured the concentrations of total phosphorus, total organic nitrogen, chlorophyll a, total, fixed and volatile suspended solids, as well as the measure of transparency (Secchi) and the profiles of photosynthetic active radiation (PAR), temperature, pH, dissolved oxygen and electrical conductivity in the water column. Measurements of vertical profiles have shown some periods of chemical and thermal stratification, especially in the rainy season, due to increased water column depth, however, the reservoir can be classified as warm polimitic. During the study period the reservoir was characterized as eutrophic considering the concentrations of phosphorus and most of the time as mesotrophic, based on the concentrations of chlorophyll a, according to the Thornton & Rast (1993) classification. The N:P relations suggest N limitation, conversely, significant linear relationship between the algae biomass and nutrients (N and P) were not observed in our study. However, a relevant event was the negative and significant correlation presented by Kt and chlorophyll a (r ² = 0.83) at the end of the drought of 2007 and the rainy season of 2008, and the algal biomass collapse observed at the end of the drought season (Dec/07). The equation used to simulate the change in the total phosphorus was not satisfactory, being necessary inclusion of parameters able to increase the power of the model prediction. The chlorophyll a simulation presented a good adjustment trend, however there is a need to check the calibrated model parameters and subsequent equation validation

Monitoramento por dgps e análise dos processos erosivos da linha de costa na praia de Pirangi do Norte - Parnamirim / RN

Through out the course of a steady increase in search and recovery of space in the coastal zone, there is also an expanding concern about the erosion processes of this area. The main problem in coastal areas is that urbanization occurs in a disorderly fashion and unsustainable, further aggravating the problems of coastal dynamics. The study area of this work is located on the southern coast of Pirangi do Norte beach to about 20km south of Natal, capital of Rio Grande do Norte in the Parnamirim City. This area has the length of approximately 1km, divided into three sections (Western, Central and Eastern) with a morphology consisting of a tableland at the top, sea cliffs in the West and Central parts and sand dunes in the Eastern section, both vegetated, and a coastal plain on the inferior part associated with the presence of beach rocks. This study aimed to analyze the erosion processes operating in the excerpt of Pirangi do Norte beach and assess the feasibility of their monitoring making use of DGPS (Global Positioning System Differential mode). During the work it was carried out a physical description of the area through photo-interpretation and site survey after measurement of the shoreline in the period between November 2004 and November 2009 and beach profiles between August 2005 and July 2006. The analysis of the results of the annual surveys showed the occurrence of variations of the shoreline along the stretch traveled. Sites are identified in advancement coast from the sea and it was verified in loco the presence of erosion with deposition of materials on the lower part of the coastal bluff, the former position of the shoreline, showing a false notion of advancing it. This leads to the conclusion that the data collected in a survey of the shoreline should always be accompanied by photographic records of the local area and with the highest rate of erosion, thus avoiding the mistake of treating the deposit materials as evidence of progress coast. At the end of the study, after a review of various works to mitigate the erosion in the coastal zone, it is recommended to the area of study the adoption of an artificial feeding of the beach, aiming the minimization of the erosive effects of the tides. Moreover, it is suggested that even the continuity of monitoring, maintenance of existing vegetation and control of the occupation on the edge of sea cliffs

Influência dos modelos digitais de terreno na modelagem de circulação hidrodinâmica 2DH: um estudo de caso

Digital Elevation Models (DEM) are numerical representations of a portion of the earth surface. Among several factors which affect the quality of a DEM, it should be emphasized the attention on the input data and the choice of the interpolating algorithm. On the other hand, several numerical models are used nowadays to characterize nearshore hydrodynamics and morphological changes in coastal areas, whose validation is based on field data collection. Independent on the complexity of the physical processes which are modeled, little attention has been given to the intrinsic bathymetric interpolation built within the numerical models of the specific application. Therefore, this study aims to investigate and to quantify the influence of the bathymetry, as obtained by a DEM, on the hydrodynamic circulation model at a coastal stretch, off the coast of the State of Rio Grande do Norte, Northeast Brazil. This coastal region is characterized by strong hydrodynamic and littoral processes, resulting in a very dynamic morphology with shallow coastal bathymetry. Important economic activities, such as oil exploitation and production, fisheries, salt ponds, shrimp farms and tourism, also bring impacts upon the local ecosystems and influence themselves the local hydrodynamics. This fact makes the region one of the most important for the development of the State, but also enhances the possibility of serious environmental accidents. As a hydrodynamic model, SisBaHiA® - Environmental Hydrodynamics System ( Sistema Básico de Hidrodinâmica Ambiental ) was chosen, for it has been successfully employed at several locations along the Brazilian coast. This model was developed at the Coastal and Oceanographical Engineering Group of the Ocean Engineering Program at the Federal University of Rio de Janeiro. Several interpolating methods were tested for the construction of the DEM, namely Natural Neighbor, Kriging, Triangulation with Linear Interpolation, Inverse Distance to a Power, Nearest Neighbor, and Minimum Curvature, all implemented within the software Surfer®. The bathymetry which was used as reference for the DEM was obtained from nautical charts provided by the Brazilian Hydrographic Service of the Brazilian Navy and from a field survey conducted in 2005. Changes in flow velocity and free surface elevation were evaluated under three aspects: a spatial vision along three profiles perpendicular to the coast and one profile longitudinal to the coast as shown; a temporal vision from three central nodes of the grid during 30 days; a hodograph analysis of components of speed in U and V, by different tidal cycles. Small, but negligible, variations in sea surface elevation were identified. However, the differences in flow and direction of velocities were significant, depending on the DEM

Remoção de Microalgas de efluentes de lagoas de estabilização utilizando biofiltro

This research evaluated the microalgae removal produced in a stabilization pond system using biofilters as post-treatment, besides characterizing the effluents of stabilization ponds and filters in relation to concentrations of algal biomass (chlorophyll a and suspended solids), organic matter (BOD and COD), total phosphorus, orthophosphate, pH and dissolved oxygen, and tried to correlate physicochemical parameters with chlorophyll "a". It was held at the Ponta Negra ETE which is constituted by three stabilization ponds, with a primary facultative pond and two of maturation. For the algae removal were used two submerged bio-filters: the filter FPF (Facultative Pond Filter), fed with facultative pond effluent; and the filter MPF (Maturation Pond Filter), fed with second maturation pond effluent. The filling material of both filters was predominantly gravel no. 2, although it contains portions of gravel no. 1 and no. 3. The filters operating conditions were bad, they were nearly 10 years without maintenance, without cleaning or removal of sludge since the time of its construction, and part of the filling material may be obstruct. Despite poor operating conditions were obtained satisfactory results, in level of posttreatment. Removal efficiencies in relation to BOD and COD were 7 and 25% in FPF and 9 and 19% and in MPF, respectively. In relation to TSS efficiencies in MPF and FPF were 37 and 20%, respectively. As for the chlorophyll "a" removal, the FPF efficiency was 44% and the MPF was 40%. There was 50% of consumption of dissolved oxygen, on average, within the filters. Two profiles were performed in the filters, and it was possible to conclude that variations throughout the day were not statistically significant, and that, regardless of the time of collection, they would have the same representation comparing to the time of data collection (7 am) and the daily average, although individual variations throughout the day have been shown to be significant. Another important observation is that the correlations between Chlorophyll a and TSS were bigger and more significant in the effluent of the filters than in the effluent of the ponds

O leitor universitário e a construção das práticas de ler e escrever textos impressos e digitais

The construction of a mapping of the practices of reading and writing printed and digital texts, declared by graduating students from the Bachelor s degree in Science and Technology (BCT), has provided us the analysis of the course they are making in such a socio-historical moment characterized by the revolution of the post-paper. In this sense, the general objective of this research is to understand how that construction works under the point of view of those graduating students. For this, our reflection has been guided by the search of answers for some questions which have presented to us: what reading and writing conceptions BCT graduating students have; what reading and writing practices those collaborators develop; what collections they declare to have access to; what differences they declare to have between printed and digital reading and writing along the different social roles they develop; what the reader/writer identity relations of those collaborators are. To achieving the plausible answers, we have gathered a corpus composed by texts of three genres of the argument order: academic profiles (or self-portrait), opinion articles and argumentative letters. Besides, we have made semi-structured interviews and questionnaires in the online tool of the Google Docs. The methodology which supports this academic work is the qualitative research (SIGNORINI; CAVALCANTI, 1998)of ethnographic direction (THOMAS, 1993; ANDRÉ, 1995) in Applied Linguistics (CELANI, 2000; MOITA-LOPES, 2006) and the theoretical contribution comes from the bakhtinian perspective of language conception (BAKHTIN [1929] 1981); the socio-historical writing construction (LÉVY, 1996; CHARTIER, R., 1998, 2002, 2007; COSCARELLI, 2006; CHARTIER, A., 2007; ARAÚJO, 2007; COSCARELLI; RIBEIRO, 2007; XAVIER, 2009; MARCUSCHI; XAVIER, 2010); from the studies of the pedagogy of the writing (GIROUX, 1997); from the literacy studies understood as sociocultural practice, plural and situated (TFOUNI, 1988; KLEIMAN, 1995; TINOCO, 2003, 2008; OLIVEIRA; KLEIMAN, 2008), from the studies about identity in postmodernity (HALL, 2003; BAUMAN, 2005). The results of the analysis have pointed at a multiplicity of reading/writing practices of printed and digital texts developed by the BCT graduating students due to the coexistence of the modality printed and that one derived from the new mobile devices. In that multiplicity, the prevalent idea of the collaborators is that there is a continuum between printed texts and digital texts (not a dichotomy), since the option of reading/writing printed texts or digital ones is always linked to specific communication situations, which involve participants, objectives, strategies, values, (dis)advantages, besides (re)creation of discursive genres in function of the mobile devices to which those collaborators have access in the different spheres of activities that they participate. All of that has caused a deep intersection in the identity traces of college students readers/writers in the 21st century which cannot be ignored by academic formation

Práticas de leitura e escrita na formação em ciências e tecnologia

The discussion about the need of improving the reading and the writing practices of professionals from the most different knowledge areas has caused, in Brazilian and foreign institutions of higher education, a movement of insertion of curricula components whose focus is the reading and the writing in academic formation. To contributing with the reflection about that discussion, this master s degree dissertation has as object of study the situated linguistic formation. Our general objective is to analyze a linguistic formation proposal to graduating students from the Bachelor s degree in Science and Technology (BCT) of the Federal University of Rio Grande do Norte (UFRN). To constructing that analysis, we have established four specific objectives: a) verifying if the ten brazilian Institutions of Higher Education which offer the BCT have curricula components of reading and writing directed to that formation; b) describing how these Bachelor s degree reading and writing curricula components are presented; c) examining differences and similarities which, in general, exist among curricula components related to reading and writing in each one of the researched institutions; d) revealing which categories delineate the linguistic formation developed in the BCT of the UFRN. In order to reaching our goals, this work has been based on the dialogical conception of the language (BAKHTIN [1952-1953] 2010), on the literacy studies (KLEIMAN [1995] 2008; TINOCO, 2008) and on the critical pedagogy (FREIRE, 1980; 2007). Methodologically, this qualitative research of ethnographic direction (ANDRÉ, 1995) is grounded in Applied Linguistics (PEREIRA; ROCA, 2009; PASCHOAL; CELANI (Orgs.), 1992). This research has the contribution of professors, scholars and monitors of the field of Reading and Writing Practices (PLE) and also graduating students from the UFRN BCT which had already studied PLE-I and/or PLE-II. The tools used for data collection/generation were: curricula components programs related to reading and writing in the BCT in the researched higher education institutions (IES), questionnaires, semi-structured interviews and profiles. The generated data allowed us to establish the following analysis categories: situationality (real situation, thematic contemporaneity and thematic focalization) and literacy projects (learning community and protagonism). The results achieved show that most IES which offer BCT worry about improving the reading and writing competences of their graduating students; however, there is still a lot to be done (increase of the number of class hours, contents and methodological aspects review, theoretical referential sophistication) so that the curricula components can be configured as a situated and significant linguistic formation. Finally, we make some suggestions for improving the work which has been made in the BCT of the UFRN, making then the mother tongue teaching in courses of the area of exact and technological sciences stronger

A aprendizagem de inglês mediada por jogos eletrônicos do tipo MMORPG

Massively Multiplayer Online Role-Playing Games (MMORPGs) are role-playing games that, through the Internet, can integrate thousands of players interacting at the same time in at least one virtual world. This way, these games can provide, further than fun, a greater familiarity with the additional language and opportunity to improve the linguistic proficiency in a real context. Hence, what is proposed in this study is extended knowledge about the learning of an additional language mediated by MMORPGs for teachers to know how, if relevant, to present, use or encourage this practice to their students. Based on this major purpose, we seek to answer the following research questions: (a) what distinguishes the learning profile of the gamers and non-gamers; (b) if MMORPGs can, through a hybrid and systematic approach, assist the development of proficiency of the additional language and (c) what the think-aloud protocols show about the learning mediated by the MMORPG Allods Online. Following an experimental method (NUNAN, 1997), 16 students of the curricular component Reading and Writing Practices in English Language have comprised the control group and 17 students of the same class formed the experimental group and were submitted to a pre and post-test adapted from the Key English Test (KET) by the Cambridge University (2008). The tests were conducted before and after a period of 5 weeks of 3 hours of practice with Allods Online a week (experimental group), and classes of the curricular component (both groups). A quantitative analysis of the questionnaires about the exposure to English profiles of the participants, a quantitative analysis of the tests scores and a qualitative analysis of the thinkaloud protocols collected during the experiment were conducted based on the theories of (a) motivation (GARDNER, 1985, WILLIAMS & BURDEN, 1997, BROWN, 2007, HERCULANO-HOUZEL, 2005); (b) active learning (GASS, 1997, GEE, 2008, MATTAR, 2010); (c) interaction and collaborative learning (KRASHEN, 1991, GASS, 1997, VYGOTSKY, 1978); (d) situated learning (DAMASIO, 1994; 1999; 2003, BROWN, 2007, GEE, 2003) and (e), tangential learning (PORTNOW, 2008; MATTAR, 2010). The results indicate that the participants of the experimental group (gamers) seem to be more engaged in tangential English learning activities, such as playing games, listening to music in English, communicating with foreigners and reading in English. We also deduced that the period of experiment possibly generated positive results on the gamers proficiency scores, mainly in the parts related to orthographic development, reading and comprehension, writing with focus on content and orthographic accuracy. Lastly, the think-aloud protocols presented evidences that the gamers have engaged in active English language learning, they have interacted in English with other players, and learned linguistic aspects through the experience with the MMORPG Allods Online

Imagens mí(s)ticas do gato

La valeur évocative, magique ou my(s)thique attribuée à la relation homme/animal peut être observée dans la culture depuis les époques lointaines. Dans la symbologie animale on trouve une immense charge sémantique justifiant les croyances les plus anciennes que les êtres humains ont déjà eues. Les animaux sont à la base du symbolisme mythique et ils se constituent en tant qu une source pour la riche production artistique englobant une grande variété iconographique et des textes de nature diverse. Ayant comme référence de la symbologie animal l image my(s)thique du chat, on observe la façon par laquelle le langage poétique contemple les profils mythiquesymboliques qui ont un rapport avec ce langage, tout en mettant en relief ceux qui ont des rapports aux relations entre le monde humain et le félin. À partir de l antologie tématique Assinar a pele ; des concepts théoriques ; et des abordages mitocritiques, nous cherchons à analyser les façons par lesquelles les différentes images mythiques associées au chat ont été explorées par la poésie. La définition d une typologie englobant des catégories telles : chat domestique, chat de rue, chat femme, chat nocturne, chat démoniaque et chat divin, parmi d autres, soutient la reconnaissance d identités possibles entre ces poèmes et signale la répétition d un répertoire symbolique divers en soi, mais, cohérent avec la présence du chat dans la société humaine à travers les temps

Inês de Castro no romance contemporâneo português

Ines de Castro is a theme in literature from the fourteenth century. The historical fact of his death, in 1355, became a landmark in the history of Portugal and, since then, several literary texts from various genres, have dealt with this theme, this made the couple Pedro and Ines a myth of love passion, of love beyond the barriers of death, like Tristan and Isolde, Romeo and Juliet, Abelard and Heloise. The literary myth - or any picture that mythologize literature - is always prepared before culturally and works in the same way that so many others, this is, as an element of cultural identity, either collectively or individually, making it also a feature poetic. Thereby, is an archetype confirmed through time and eventually reveals a series of webs of the human psyche. Ines de Castro became the Portuguese myth of eternal love: she became queen after your dead. The persistence of the myth makes the love story of Pedro and Ines continue to produce texts of various literary genres. This study examines six contemporary historical novels, to show that the way actually this kind o novel does a new formulacion of Pedro e Ines mythical, because now it s different view likes the victim in Os lusiadas and other texts from the past. Collaborate to this news relacions between history and literature and a novelist's new stance in relation to historical facts that relate like reffering to novel. The intention is to show, through the novels chosen now Ines de Castro have different profiles than it had before in tradicional historic novels from the period of Romanticism and New Romanticism. Authored by Agustina Bessa-Luís, João Aguiar, António Cândido Franco, Seomara da Veiga Ferreira and Luis Rosa, the six novels studied show the circularity cultural of inesian myth showing this new character of the new person Ines in the contemporany historical novel

Mídias sociais e práticas de participação política: um estudo de caso das eleições municipais 2012, em Natal

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

Ondaletas e movimento browniano fracionário: aplicação à caracterização de poços de petróleo

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

Parâmetros físico-químicos de estrelas nos campos de exoplanetas do satélite corot

A rotação estelar é um dos mais importantes observáveis da evolução estelar. Neste sentido, o satélite CoRoT representa uma oportunidade única de medir os períodos rotacionais para uma amostra de estrelas estatisticamente robusta, oferecendo dados absolutamente necessários para o estudo da rotação e seu papel na evolução estelar. Para conseguir isto, um passo fundamental é a caracterização física e química das estrelas observadas pelo CoRoT, especificamente devido ao fato de que o cálculo de períodos rotacionais confiáveis é um trabalho difícil sem a ajuda dos parâmetros estelares. Desta forma, foi elaborado um importante seguimento observacional das estrelas nos campos do CoRoT do anticentro LRa01 e do centro LRc01, permitindo a correta identificação dos períodos que reflitam a modulação rotacional. Nesta tese de doutorado são apresentados os resultados de tal seguimento. Parâmetros físicos e químicos, tais como temperatura efetiva Teff , gravidade superficial log(g), velocidade de microturbulência Vmic, abundância de ferro [Fe/H], velocidade de rotação projetada Vsin(i), e abundância de lítio A(Li) são apresentados para uma amostra de 116 estrelas dos campos CoRoT. Elas se encontram em diferentes estágios evolutivos, desde a sequência principal (SP) até o ramo das gigantes vermelhas (GV). As observações foram feitas utilizando os espectrógrafos UVES (VLT) e HYDRA (CTIO). Para a derivação de tais parâmetros foram utilizados o programa TurboSpectrum e os modelos de atmosfera de MARCS. Paralelamente, velocidades rotacionais Vsin(i) foram obtidas a partir do ajuste dos perfis observados e sintéticos das linhas de ferro e por meio de uma calibração de função de correlação cruzada (CCF). Períodos rotacionais Prot para 77 estrelas da amostra foram obtidos a partir das curvas de luz do satélite CoRoT. Extensas tabelas destes parâmetros e seus respectivos erros são apresentadas. Foram encontradas diferenças nas distribuições de Teff , [Fe/H] e estágios evolutivos entre os diferentes campos do CoRoT, indicando possíveis efeitos de seleção na amostra, assim como a existência de diferentes populações estelares do disco Galáctico. Por outro lado, o comportamento rotacional e as abundâncias de lítio não apresentam diferenças entre estrelas de parâmetros físicos similares, mas que pertencem a diferentes campos do CoRoT. A partir da análise de temperaturas, foi encontrada uma maior extinção por avermelhamento para estrelas do CoRoT localizadas no campo LRc01, assim como um gradiente deste valor em função da distância. Os resultados mostram que as abundâncias de lítio, as velocidades de rotação e os períodos rotacionais apresentam o mesmo comportamento descrito na literatura. Por outro lado, é apresentada pela primeira vez a relação que existe entre o lítio e o período de rotação em diferentes estágios evolutivos, mostrando, tal como era esperado, que ambas as grandezas possuem uma anticorrelação. Também é apresentada a evolução simultânea da rotação e do lítio, e foram calculadas relações que permitem obter valores médios de A(Li) como função da temperatura efetiva e do período rotacional. Os dados apresentados nesta tese de doutorado representam um importante ponto de partida para serem utilizados como uma amostra de calibração para diferentes programas no contexto da missão do satélite CoRoT, uma vez que a lista de estrelas aqui analisadas são parte das mais brilhantes que compõem o campo Exo do CoRoT