43 resultados para Fractais de Koch
Resumo:
Embora tenha sido proposto que a vasculatura retínica apresenta estrutura fractal, nenhuma padronização do método de segmentação ou do método de cálculo das dimensões fractais foi realizada. Este estudo objetivou determinar se a estimação das dimensões fractais da vasculatura retínica é dependente dos métodos de segmentação vascular e dos métodos de cálculo de dimensão. Métodos: Dez imagens retinográficas foram segmentadas para extrair suas árvores vasculares por quatro métodos computacionais (“multithreshold”, “scale-space”, “pixel classification” e “ridge based detection”). Suas dimensões fractais de “informação”, de “massa-raio” e “por contagem de caixas” foram então calculadas e comparadas com as dimensões das mesmas árvores vasculares, quando obtidas pela segmentação manual (padrão áureo). Resultados: As médias das dimensões fractais variaram através dos grupos de diferentes métodos de segmentação, de 1,39 a 1,47 para a dimensão por contagem de caixas, de 1,47 a 1,52 para a dimensão de informação e de 1,48 a 1,57 para a dimensão de massa-raio. A utilização de diferentes métodos computacionais de segmentação vascular, bem como de diferentes métodos de cálculo de dimensão, introduziu diferença estatisticamente significativa nos valores das dimensões fractais das árvores vasculares. Conclusão: A estimação das dimensões fractais da vasculatura retínica foi dependente tanto dos métodos de segmentação vascular, quanto dos métodos de cálculo de dimensão utilizados
Resumo:
The present study provides a methodology that gives a predictive character the computer simulations based on detailed models of the geometry of a porous medium. We using the software FLUENT to investigate the flow of a viscous Newtonian fluid through a random fractal medium which simplifies a two-dimensional disordered porous medium representing a petroleum reservoir. This fractal model is formed by obstacles of various sizes, whose size distribution function follows a power law where exponent is defined as the fractal dimension of fractionation Dff of the model characterizing the process of fragmentation these obstacles. They are randomly disposed in a rectangular channel. The modeling process incorporates modern concepts, scaling laws, to analyze the influence of heterogeneity found in the fields of the porosity and of the permeability in such a way as to characterize the medium in terms of their fractal properties. This procedure allows numerically analyze the measurements of permeability k and the drag coefficient Cd proposed relationships, like power law, for these properties on various modeling schemes. The purpose of this research is to study the variability provided by these heterogeneities where the velocity field and other details of viscous fluid dynamics are obtained by solving numerically the continuity and Navier-Stokes equations at pore level and observe how the fractal dimension of fractionation of the model can affect their hydrodynamic properties. This study were considered two classes of models, models with constant porosity, MPC, and models with varying porosity, MPV. The results have allowed us to find numerical relationship between the permeability, drag coefficient and the fractal dimension of fractionation of the medium. Based on these numerical results we have proposed scaling relations and algebraic expressions involving the relevant parameters of the phenomenon. In this study analytical equations were determined for Dff depending on the geometrical parameters of the models. We also found a relation between the permeability and the drag coefficient which is inversely proportional to one another. As for the difference in behavior it is most striking in the classes of models MPV. That is, the fact that the porosity vary in these models is an additional factor that plays a significant role in flow analysis. Finally, the results proved satisfactory and consistent, which demonstrates the effectiveness of the referred methodology for all applications analyzed in this study.
Resumo:
Although it has been suggested that retinal vasculature is a diffusion-limited aggregation (DLA) fractal, no study has been dedicated to standardizing its fractal analysis . The aims of this project was to standardize a method to estimate the fractal dimensions of retinal vasculature and to characterize their normal values; to determine if this estimation is dependent on skeletization and on segmentation and calculation methods; to assess the suitability of the DLA model and to determine the usefulness of log-log graphs in characterizing vasculature fractality . To achieve these aims, the information, mass-radius and box counting dimensions of 20 eyes vasculatures were compared when the vessels were manually or computationally segmented; the fractal dimensions of the vasculatures of 60 eyes of healthy volunteers were compared with those of 40 DLA models and the log-log graphs obtained were compared with those of known fractals and those of non-fractals. The main results were: the fractal dimensions of vascular trees were dependent on segmentation methods and dimension calculation methods, but there was no difference between manual segmentation and scale-space, multithreshold and wavelet computational methods; the means of the information and box dimensions for arteriolar trees were 1.29. against 1.34 and 1.35 for the venular trees; the dimension for the DLA models were higher than that for vessels; the log-log graphs were straight, but with varying local slopes, both for vascular trees and for fractals and non-fractals. This results leads to the following conclusions: the estimation of the fractal dimensions for retinal vasculature is dependent on its skeletization and on the segmentation and calculation methods; log-log graphs are not suitable as a fractality test; the means of the information and box counting dimensions for the normal eyes were 1.47 and 1.43, respectively, and the DLA model with optic disc seeding is not sufficient for retinal vascularization modeling
Resumo:
The thesis, entitled, Pedagogical/comunication knowledge, research/formation: Reflections on the formative experiences of teachers online , developed dialogues on the pedagogical/communication knowledge, research-formation and the formative experiences of teachers online, for the purpose of understanding how pedagogical/communication knowledge is establishing/established from the formative experience of teachers online. For this reason we began with the following question: how does pedagogical/communication knowledge become estabilishing/established beginning with the formative experience of teachers online? The methodological approach for the selected research was research/formation, based on Ethnoresearch of critical formation. This became a rich route for reflections on pedagogical/communication knowledge and formative experiences, making a contribution for formation and autoformation of the teacher/researcher and the teachers online. This provided moments of formation, of reflection-in-action and on the action, potentialized/structured the process of comprehending, analyzing, interpreting, reflecting on the formative experiences and contributing for reflections on pedagogical/communication knowledge of the teacher online. The theoretical referential dialogue was based on concepts such as: education online, interactivity Silva (2002), Santos (2005), Moran (2003), teaching, Veiga (2005), Pimenta (2002), Freire (2005), Tardif (2002), teaching online Sacramento (2006), teaching knowledge Tardif (2002), Charlot (2000), Porlán (1997), García (1992), Freire (2005), Ethnoresearch-formation Macedo (2000), formation Macedo (2010), Josso (2010). The discoveries revealed that the pedagogical/communication knowledged becomes establishing/established beginning with formative experience of the teachers online, from the emergency of a collective communicative dialogue, structuring and potentialized by the experiences of the context online, from the didactic pedagogical/communicational organization online, of the research, of the relation created by the expertise and the presents itself along the itinerary of the family , the school, academic and professional. From this we can conclude that of knowledge and plural experiences, which became broken down because they are parts that relate themselves with other parts, which become united in one whole, the singular/plural, the local/global, the text and the context, agregating principles a pedagogical- communication perspective that orients :the dialogue, the interactivity, the hypertextuality, themultivocallity, formative dispositions, formative experiences all of wich makes for the possibilities for researdh and the training of professors and teachers who accept their point of departure and enddind points as pedagogy and experience
Resumo:
The bidimensional periodic structures called frequency selective surfaces have been well investigated because of their filtering properties. Similar to the filters that work at the traditional radiofrequency band, such structures can behave as band-stop or pass-band filters, depending on the elements of the array (patch or aperture, respectively) and can be used for a variety of applications, such as: radomes, dichroic reflectors, waveguide filters, artificial magnetic conductors, microwave absorbers etc. To provide high-performance filtering properties at microwave bands, electromagnetic engineers have investigated various types of periodic structures: reconfigurable frequency selective screens, multilayered selective filters, as well as periodic arrays printed on anisotropic dielectric substrates and composed by fractal elements. In general, there is no closed form solution directly from a given desired frequency response to a corresponding device; thus, the analysis of its scattering characteristics requires the application of rigorous full-wave techniques. Besides that, due to the computational complexity of using a full-wave simulator to evaluate the frequency selective surface scattering variables, many electromagnetic engineers still use trial-and-error process until to achieve a given design criterion. As this procedure is very laborious and human dependent, optimization techniques are required to design practical periodic structures with desired filter specifications. Some authors have been employed neural networks and natural optimization algorithms, such as the genetic algorithms and the particle swarm optimization for the frequency selective surface design and optimization. This work has as objective the accomplishment of a rigorous study about the electromagnetic behavior of the periodic structures, enabling the design of efficient devices applied to microwave band. For this, artificial neural networks are used together with natural optimization techniques, allowing the accurate and efficient investigation of various types of frequency selective surfaces, in a simple and fast manner, becoming a powerful tool for the design and optimization of such structures
Resumo:
Frequency selective surfaces (Frequency Selective Surface - FSS) are often used in various applications in telecommunications. Some of these applications may require that these structures have response with multiple resonance bands. Other applications require that the FSS response have large frequency range, to meet the necessary requirements. FSS to design with these features there are numerous techniques cited in the scientific literature. Thus, the purpose of this paper is to examine some common techniques such as: Overlap of FSS; Elements combined; Elements Elements convolucionados and fractals. And designing multiband FSS and / or broadband selecting simple ways in terms of construction and occupy the smallest possible space, aiming at practical applications. Given these requirements, three projects FSS were performed: a technology applied to IEEE 802.11 a/b/g/n and two projects for application in UWB. In project development, commercial software Ansoft DesignerTM and experimental results were satisfactory was used
Resumo:
Esta pesquisa trata da referenciação ocorrida pelas anáforas diretas e indire-tas em produções textuais de alunos do Ensino Fundamental. Como elemento pri-mordial de nossas investigações, ancoramo-nos na referenciação e estudos da aná-fora no âmbito da Lingüística Textual como fazem Mondada e Dubois (2003); KOCH (2003) e Marcuschi (2005). De acordo com estudos já realizados e envolvidos com a temática, defendemos a noção de referenciação como sendo um processo de cons-trução de sentidos que se realiza no discurso, isto é, em atividades interativas entre os sujeitos exigindo, portanto, uma ação colaborativa entre os interlocutores. Nesse aspecto, a interação precisa existir, visto que os referentes de um termo anafórico nem sempre se encontram na superfície textual; muitas vezes, são construídos a partir de uma representação ou modelo mental disponível na memória discursiva. Nessa perspectiva, procuramos analisar o processo de referenciação construído a partir de anáforas diretas e indiretas identificando as estratégias utilizadas em textos produzidos em situações de sala de aula. Dizemos que a anáfora direta, de modo geral, é definida pela relação de correferencialidade estabelecida entre o anafórico e seu antecedente, enquanto a anáfora indireta é vista como uma estratégia referenci-al de associação, sem referente explícito, tendo que se esforçar para estabelecer a continuidade referencial no texto e para isso utiliza-se da ativação (referenciação mental) de elementos novos e não de uma reativação de referentes já conhecidos, o que constitui um processo de referenciação implícita. Para alcançarmos nosso obje-tivo, utilizamos como subsídio teórico, o processo de informação na memória cogni-tiva, a referência e estudos da anáfora no âmbito da Lingüística Textual. O corpus deste trabalho constitui-se de sessenta textos escritos por alunos de 7ª série (atual 8º ano), dentre os quais analisamos o processo de referenciação ocasionado pelas anáforas diretas e indiretas em doze desses textos. Considerando os dados analisa-dos, dentre os tipos de anáforas estudados, constatamos que houve preponderância no uso das anáforas diretas, destacando-se entre elas a anáfora direta correferencial co-significativa, com maior manifestação no uso das retomadas diretas por pronomi-nalização
Resumo:
In this study we investigate the reference to other s discourse done it through the resource of direct cited discourse at background section in monographic texts produced by university students at the last phase of final work in their graduate Letras course. This work is guided in cited/related discourse studies in Bakhtin (2004), Authier-Revuz (1990, 1998, 2004), Maingueneau (1996, 2002), Charaudeau and Maingueneau (2004); in genre approaches developed by Bakhtin (2000); Maingueneau (1996, 2002); socio-discursive interaction (BRONCKART, 1999, 2003; SCHNEUWLY, 2004; DOLZ e SCHNEUWLY, 2004) and Bazerman (2005); and also in presuppositions of Textual Linguistics presented by Charrolles (1988), Van Dijk (1997), Beaugrande and Dressier (1981), Koch and Travaglia (1993, 1995), Koch (2002, 2004) and Val (2000, 2004). We have established as aims to analyze and interpret meaning relations problems in how to articulate direct cited discourse with citing discourse and at the same time explain semantic implications that comes from that articulation that compromise text meaning, at background section in that monographic genre. The analysis, by qualitative and quantitative basis in eleven monographic works that form our corpus, gave us the opportunity to achieve and see that meaning relationships in the articulation of direct cited discourse with citing discourse show problems that may be categorized into three different groups: problems related to meaning relationships with citing discourse that comes before it, problems of meaning relationships with citing discourse that comes after it, and problems with of meaning relationships with citing discourse that come before it and at the same time with citing discourse that comes after it (i.e. in relation to both). These analysis also allow us assert that, these problems, just because they occur frequently, they affect the micro level text coherence, and they also compromise the text global meaning. The results show that students at Letras Course, even in the ending process of their course do not show the real domain in relation to some ways of direct cited discourse organization and working, and also how the ideas articulation work in the construction of relations between direct cited discourse and the citing discourse that can turn those students able to produce a text that enhance acceptable patterns
Resumo:
In this work, the argumentative strategies construction in university entrance examinations texts is analyzed. The study intended to present, through the analyzed occurrences in the corpus, the discursive strategies use for the argumentation construction, observing the different lexicalization forms and the effects that these strategies produced for the intended meaning construction. Aiming to analyze the modalization via texts written by candidates for the UFRN entrance examination, the relations between this category and the resources used for the argumentative guidance of the text were highlighted. Conceived as a speaker argumentative strategy to express his/her relationship with the proposition content which enunciates, the modalization is, thus, one of the linguistic expression form used for the attainment of intended meaning effects in the argumentation construction. In order to substantiate the research, the theoretical assumptions adopted were the propositions which deal with this linguistic category, guiding it to a pragmatic-semantic perspective as well as a discursive-semantic one. Hence, Neves ( 1996, 2006), Koch ( 2000, 2002), Cervoni ( 1989), Bronkart (1999) and Castilho; Morais de Castilho (1996) studies, among others founded this work. Afterwards, a contextualized analysis of the modalized statements, taking into account all the set of elements implied on the argumentation construction, was carried out. The research, which had a strict qualitative character, revealed that the candidates make use of modalization to express commitment or dissociation as regards the statement which they produce; to obtain credibility and provide more authority to their arguments, thus avoiding them of being contested; to impose their arguments as real ones and acquire acceptance of the interlocutor; to lessen the proposition content and disguise the knowledge source; to comment the enunciation and attribute the discourse to another sender; to establish a dialogic relation with the interlocutor. In addition to offering support for new investigations, the research also aims to contribute for the mother tongue teaching, emphasizing the need of a focus which provides special attention to the written language functioning and its application diversity. In this work, the argumentative strategies construction in university entrance examinations texts is analyzed. The study intended to present, through the analyzed occurrences in the corpus, the discursive strategies use for the argumentation construction, observing the different lexicalization forms and the effects that these strategies produced for the intended meaning construction. Aiming to analyze the modalization via texts written by candidates for the UFRN entrance examination, the relations between this category and the resources used for the argumentative guidance of the text were highlighted. Conceived as a speaker argumentative strategy to express his/her relationship with the proposition content which enunciates, the modalization is, thus, one of the linguistic expression form used for the attainment of intended meaning effects in the argumentation construction. In order to substantiate the research, the theoretical assumptions adopted were the propositions which deal with this linguistic category, guiding it to a pragmatic-semantic perspective as well as a discursive-semantic one. Hence, Neves ( 1996, 2006), Koch ( 2000, 2002), Cervoni ( 1989), Bronkart (1999) and Castilho; Morais de Castilho (1996) studies, among others founded this work. Afterwards, a contextualized analysis of the modalized statements, taking into account all the set of elements implied on the argumentation construction, was carried out. The research, which had a strict qualitative character, revealed that the candidates make use of modalization to express commitment or dissociation as regards the statement which they produce; to obtain credibility and provide more authority to their arguments, thus avoiding them of being contested; to impose their arguments as real ones and acquire acceptance of the interlocutor; to lessen the proposition content and disguise the knowledge source; to comment the enunciation and attribute the discourse to another sender; to establish a dialogic relation with the interlocutor. In addition to offering support for new investigations, the research also aims to contribute for the mother tongue teaching, emphasizing the need of a focus which provides special attention to the written language functioning and its application diversity
Resumo:
In this work we present the results of a research that aims to study the chronicle gender produced in a class of native language. The texts were written by students of a high-school class, under the orientation of the teacher who conducted a didactic sequence in order to explore this gender. In our analysis we observed aspect such as the structure of the general structure of the texts, types of speech and linguistic sequences, some mechanisms of textualization and the characteristics of the gender. In order to attain that, we adopted the theoretical presuppositions of Textual Linguistics and of the Socio-discursive Interactionism, grounding the study of texts and gender in Bronckart (2003; 2006) and Koch (2002; 2004). As a background of the Chronicle Gender we used the studies of Coutinho (1987); Moisés (2003); Sá (2005); Bender; Laurito (1993); Melo (1994); Cândido et al. (1992) among others. The corpus, made up of 15 texts, showed that the narrative is the most used linguistic sequence in the producing of the texts, the discursive world prevailing in the narrative and some instances of the world of exposing. As for the gender characteristics, the daily life was used in order to amuse the reader and make him to reflect upon the daily life. Humor, irony, social criticism and colloquial language were also observed in the texts produced by the students. Although some texts presented the characteristics of the gender, explored in the classroom, some were typically school narratives. That make us believe that a work with textual production under the approach of a text gender is viable, but it is not consolidated yet in many schools as the main object of the central teaching of the Portuguese language. This make us defend a better systematization of the teaching contents having as the main point the reading practice and text production in order to contribute for the growing of the students´ discursive potentialities and, therefore, their effective participation in the language social practices
Resumo:
This work aims to identify, describe and analyze the main mechanisms of reference present in the texts produced by students that are finishing their fundamental school. With this in mind, we observe 46 Portuguese classes. The class was in its 9th Fundamental level, in a public school of the Cruzeta, RN. In this period, we collected our corpus that is composed by the papers that students produced. This research has an ethnographic approach and it has as theoretical support some studies about some mechanisms of reference, specifically, the lexical repetition and anaphor. In general, we are based on the studies about cohesive mechanisms from authors as Adam (2008); Beaugrande and Dressler (1981, 1997); Koch (1999, 2004, 2005, 2008), Marcuschi (1983, 1992, 2005, 2006); Bessa Neto (1991) and Neves (2006). In the corpus, we could identify some lexical repetitions (literal, with estrutural variation), as well as, anaphors, mainly pronominal ones. Then, we can notice that most students have showed difficulties in the use of those mechanisms of reference as a strategy of textual progression
Resumo:
This work aims to identify, describe and analyze the main mechanisms of reference present in the texts produced by students that are finishing their fundamental school. With this in mind, we observe 46 Portuguese classes. The class was in its 9th Fundamental level, in a public school of the Cruzeta, RN. In this period, we collected our corpus that is composed by the papers that students produced. This research has an ethnographic approach and it has as theoretical support some studies about some mechanisms of reference, specifically, the lexical repetition and anaphor. In general, we are based on the studies about cohesive mechanisms from authors as Adam (2008); Beaugrande and Dressler (1981, 1997); Koch (1999, 2004, 2005, 2008), Marcuschi (1983, 1992, 2005, 2006); Bessa Neto (1991) and Neves (2006). In the corpus, we could identify some lexical repetitions (literal, with estrutural variation), as well as, anaphors, mainly pronominal ones. Then, we can notice that most students have showed difficulties in the use of those mechanisms of reference as a strategy of textual progression
Resumo:
Cette recherche s'inscrit dans la linguistique de texte et vise à identifier, décrire, analyser et interpréter les événements de l'anaphore pronominale et de la répétition, exposer le montant et le pourcentage dês phenoménes respectifs dans Le corpus étudiés, que l accent sur le fonctionnement cohérente de ces phénomènes dans la construction du texte en termes de continuité et de progression thématique. Nous avons utilisé des procédures ethnographiques pour construire notre corpus d'enquête, composé essentiellement de textes produits par les étudiants de 9 ans d'école élémentaire de l'Etat, a la ville de Santa Cruz / RN. La recherche a été menée à partir des études sur l'anaphore pronominale faites par Milner (1982), Koch e Marcuschi (1998), Marcuschi (2000; 2005 e 2008), Koch (2002), Antunes (2005) e Adam (2008), et par des études sur la répétition présentés par Halliday e Hassan (1976), Beaugrande e Dressler (1997), Marcuschi (1992) et Antunes (2005). Comme le support technique, ont également utilisé les notions de cohésion définis par Halliday e Hasan (1976), Beaugrande e Dressler (1997), Marcuschi (2008) e Koch (2003). Dans l'analyse des textes, nous avons constaté que l'incidence de l'anaphore pronominale et de la répétition a été importante parce que les ressources étaient principalement utilisés par les étudiants pour promouvoir l'articulation cohérente des textes. Constaté que dans les textes narratifs ou argumentatifs anaphore pronominale promu l'entretien et la progression thématique prévu. Sur la répétition, nous avons observé que le maintien et la progression thématiques ont été conditionnés à la connaissance du sujet en discussion. Même si nous avons constaté que la répétition excessive de ces phénomènes dans le même texte, bien que la relation de promouvoir la cohésion, peut affecter le degré de caractere informatif
Resumo:
The diachronic studies marked the first decades of the 20th century in Brazilian linguistics, passing by an ostracism period after the 50s. Mainly from the 90s especially with the project, created in 1997, Para a história do português brasileiro (PHPB), which has systemized, in national ambit, the programme related to the area of diachrony the historical studies retake forces and have gradually increased since then. Our work is set in the new scene of Brazilian historical linguistics and it is associated to two research programmes: i) the constitution of a diachronic corpus; ii) the diachrony of text and discourse. As regards the first programme, we made effort to constitute a diachronic corpus of official letters about Rio Grande do Norte, we called cartas oficiais norte-rio-grandenses, written in 18th, 19th and 20th centuries. The chosen for bureaucrat letters occurred for they represent a textual category very productive in historical contexts, mostly 18th and 19th centuries, in which the command of writing was the least and also because they bring, almost always explicitly, the information of where, when, for whom and from whom, as remembers Fonseca (2003). The rules for constituting the corpus were based, although not strictly, on the orientation from PHPB. In respect to the second programme, we set up on the ideas of coserian base came from the studies on discourse traditions (TD) (Koch, 1997; Kabatek, 2006) amongst which that the texts are shaped so as to follow their own tradition (Coseriu, 2007), and we turned to Diplomatics (Belloto, 2002) in order to do the characterization of this corpus by the application of concepts from Diplomatics and TD as well as by the presentation of the structures that form those official letters: their textual genres, a kind of TD, with their macrostructures; and some of their formulaic expressions (microstructures), another sort of TD. This stage of characterizing will pay attention, as far as possible, to the dynamic between tradition and innovation that happen in the actualization of those textual structures along the centuries. This work intends to contribute with the researches connected to Historical Linguistics in Rio Grande do Norte, more specifically the ones related to the constitution of diachronic corpora and to TD; and with the study of official documents, textual category about which there are almost no studies (cf. Silveira, 2007)
Resumo:
The objective of this paper is to analyze how the female figure was portrayed in discursive narratives in the bi-weekly newspaper O PORVIR , which circulated in Currais Novos, in the state of Rio Grande do Norte, Brazil, between May 2, 1926 and January 20, 1929. Our analysis was based on the semantics of the text, by applying one of the primary concepts used in Textual Analysis of Speeches, Discursive Representation (ADAM, 2011; RODRIGUES; PASSEGGI; SILVA NETO, 2010). Textual Analysis of Speeches has its roots in Textual Linguistics and consists of a theoretical and descriptive approach (ADAM, 2011). This research is characterized as documentary (SEVERINO, 2007) and its corpus includes a review of 39 editions of the aforementioned newspaper, of which we extracted 292 articles that dealt with the female figure and 396 statements for analysis. We used the following semantic categories: referencing (CASTILHO, 2010; NEVES, 2007; KOCH; MARCUSCHI, 1998; MARCUSCHI, 2008; KOCH, 2009); predication (NEVES, 2007; RODRIGUES; PASSEGGI; SILVA NETO, 2010); modification (ADAM, 2011); and spacial and temporal localization (RODRIGUES; PASSEGGI; SILVA NETO, 2010). Our analysis revealed that lady, mother, wife and homemaker were most represented, and always combined with questions about motherhood, marriage and devotion to the home. Such representation does not diverge from pre-colonial models in the early twentieth century, which served as a standard for the female figure