921 resultados para Dimension fractale


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La lutte contre le travail des enfants au Burkina Faso a resurgi dans la scène publique ces dix dernières années avec un engouement sans précédent aussi bien de la part des acteurs étatiques, des ONG que des organismes onusiens. Ce chapitre traite, dans une double perspective sociologique et anthropologique, de la dimension « genre » de cette lutte et cherche à voir dans quelle mesure celle-ci est prise en compte (ou non) dans les pratiques concrètes de retrait d’enfants des travaux considérés comme dangereux. Peut-on parler de politiques et de programmes « genrés » dans le champ de la lutte contre le travail des enfants au Burkina Faso ? Le chapitre est structuré en trois parties. Il présente d’abord les éléments caractéristiques de l’approche genre dans la lutte contre le travail des enfants. Ensuite, il aborde les politiques et les acteurs de cette lutte au Burkina Faso, en décrivant les processus de problématisation et publicisation de la question. Enfin, il traite du cas spécifique d’un projet triennal de retrait d’enfants des mines artisanales des régions du Nord et du Sahel burkinabè pour questionner la prise en compte du genre, des obstacles sociaux, culturels et d’autres contraintes possibles à l’égalité fille-garçon dans cette intervention. Il questionne par ailleurs la part des acteurs de terrain dans la (re)production des normes et des rôles sexués. Les données sont issues de quatre années de recherche menée au Burkina Faso entre 2008 et 2011, auprès d’acteurs engagés dans la production des politiques de lutte et/ou engagés dans la lutte concrète, mais également avec des enfants, parents et employeurs.

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In a recent paper of Feng and Sidorov they show that for β∈(1,(1+5√)/2) the set of β-expansions grows exponentially for every x∈(0,1/(β−1)). In this paper we study this growth rate further. We also consider the set of β-expansions from a dimension theory perspective.

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We study the topology of a set naturally arising from the study of β-expansions. After proving several elementary results for this set we study the case when our base is Pisot. In this case we give necessary and sufficient conditions for this set to be finite. This finiteness property will allow us to generalise a theorem due to Schmidt and will provide the motivation for sufficient conditions under which the growth rate and Hausdorff dimension of the set of β-expansions are equal and explicitly calculable.

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We consider the billiard dynamics in a non-compact set of ℝ d that is constructed as a bi-infinite chain of translated copies of the same d-dimensional polytope. A random configuration of semi-dispersing scatterers is placed in each copy. The ensemble of dynamical systems thus defined, one for each global realization of the scatterers, is called quenched random Lorentz tube. Under some fairly general conditions, we prove that every system in the ensemble is hyperbolic and almost every system is recurrent, ergodic, and enjoys some higher chaotic properties.

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We show that the Hausdorff dimension of the spectral measure of a class of deterministic, i.e. nonrandom, block-Jacobi matrices may be determined with any degree of precision, improving a result of Zlatos [Andrej Zlatos,. Sparse potentials with fractional Hausdorff dimension, J. Funct. Anal. 207 (2004) 216-252]. (C) 2010 Elsevier Inc. All rights reserved.

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Shape provides one of the most relevant information about an object. This makes shape one of the most important visual attributes used to characterize objects. This paper introduces a novel approach for shape characterization, which combines modeling shape into a complex network and the analysis of its complexity in a dynamic evolution context. Descriptors computed through this approach show to be efficient in shape characterization, incorporating many characteristics, such as scale and rotation invariant. Experiments using two different shape databases (an artificial shapes database and a leaf shape database) are presented in order to evaluate the method. and its results are compared to traditional shape analysis methods found in literature. (C) 2009 Published by Elsevier B.V.

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Texture is an important visual attribute used to describe the pixel organization in an image. As well as it being easily identified by humans, its analysis process demands a high level of sophistication and computer complexity. This paper presents a novel approach for texture analysis, based on analyzing the complexity of the surface generated from a texture, in order to describe and characterize it. The proposed method produces a texture signature which is able to efficiently characterize different texture classes. The paper also illustrates a novel method performance on an experiment using texture images of leaves. Leaf identification is a difficult and complex task due to the nature of plants, which presents a huge pattern variation. The high classification rate yielded shows the potential of the method, improving on traditional texture techniques, such as Gabor filters and Fourier analysis.

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This article discusses methods to identify plants by analysing leaf complexity based on estimating their fractal dimension. Leaves were analyzed according to the complexity of their internal and external shapes. A computational program was developed to process, analyze and extract the features of leaf images, thereby allowing for automatic plant identification. Results are presented from two experiments, the first to identify plant species from the Brazilian Atlantic forest and Brazilian Cerrado scrublands, using fifty leaf samples from ten different species, and the second to identify four different species from genus Passiflora, using twenty leaf samples for each class. A comparison is made of two methods to estimate fractal dimension (box-counting and multiscale Minkowski). The results are discussed to determine the best approach to analyze shape complexity based on the performance of the technique, when estimating fractal dimension and identifying plants. (C) 2008 Elsevier Inc. All rights reserved.

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In this dissertation, an educational perspective called the moral dimension of teaching is developed. The work includes a theoretically informed discussion from a pragmatist point of view in which the concept of pedagogical rhythm is introduced. The concept captures the need for teachers to regularly shift their intentions and occasionally act in contradictory ways as a consequence of the moral which emerges from interaction in pedagogical situations. Using this perspective, criteria are developed for the characteristics of discussions of the work of teachers, which are desirable in order for students in pre-service teacher education to have opportunities to develop their teachership. Secondly, the educational perspective as it is conceptualised serves as a theoretical framework for a study of discussions taking place in net-based seminars among students in teacher education. The study consists of 14 recorded seminars in which discussions of the work of teachers are analysed in terms of content and direction for reflection. The result of the analysis is a construction of four different focal points for processes of making judgements: existential, performative, critical and professional. Mainly the performative, and to some extent the critical, focal points appear to be supported by the net-based environment, although potential for the professional focal point is found when available tools in net-based settings are used in deliberate ways. Finally, based on these four focal points, possible future predispositions among student teachers are deliberated. Student teachers’ future opportunities to develop a moral and epistemological authority are discussed, as well as teachers’ general opportunities to exercise professional responsibility. The conclusion emphasises that a perspective such as the one developed in the dissertation is important, as it creates an understanding for the need to educate student teachers to exercise a form of responsibility that goes beyond being accountable to society.

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Why did house prices fall in 2007‐2009? This is the fundamental question to most Americans, and to those who lent them money. Most homeowners did not care why residential real estate prices rose. They assumed prices always rose, and they should simply enjoy their good fortune. It was not until prices began to fall that people were left searching for answers. How much did regulation or lack thereof play in the role of the devastation? To what degree did greed and unrealistic consumer expectation have on the real estate bubble? Using existing literature as well as face to face interviews of experienced leaders within the real estate industry in California who experienced both the up and down of the real estate cycle, the overarching purpose of this study is to investigate the opinions and beliefs of the leaders and drivers within the real estate industry about the cause of the real estate bubble that occurred sharply in 2008 . Specifically, this project will focus on the opinions of real estate industry leaders who worked in the center of the subprime universe located in Irvine, California, during 2004‐2008. Comparing the mainstream beliefs with the interviewees it is fair to say that the main finding in the mainstream beliefs are reflected very well with the finding of the subject’s opinion. The thesis is divided into 6 chapters starting with “introduction”, followed by chapter 2 “Literature Review”. Chapter 3 is “Research Methodology” followed by chapter 4 “Data Presentation”. Finally, the results are discussed in chapter 5 “Analysis and Discussion” and conclusions in Chapter 6.

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Nota: A autora agradece à Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) pela concessão de bolsa de estudos para o desenvolvimento deste projeto de pesquisa.