Disordered Systems
Mostrando 13-24 de 47 artigos, teses e dissertações.
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13. Transição ordem-desordem da matéria de vórtices em supercondutores detectada através do terceiro harmônico da suscetibilidade AC
Although a vortex state, in type II superconductors, has been anticipated more than 50 years ago, a great deal of theoretical and experimental efforts has still been done in an attempt to investigate how the dynamics of these structures depends on external excitations and on the inherent properties of the underlying superconducting material, such as inhomoge
Publicado em: 2008
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14. Simulating the use of the agricultural sector water in the Jundiá creek basin / Simulação do uso da água do setor agrícola na bacia do Córrego Jundiá
In the past, the occurrence of the territorial occupation in Brazil was extremely disordered and the inadequate use of the natural resources caused serious negative impacts on the water resources, such as the deterioration of the water and the consequent reduction in the water availability. Nowadays, there are few tools that allow the users and management ag
Publicado em: 2008
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15. Análise multitemporal da cobertura e uso da terra, impactos ambientais e aspectos socioeconômicos do Pólo Agroflorestal Custódio Freire, Rio Branco AC / Multitemporal analysis of land use/land cover, environmental impacts and socioeconomic aspects of the Custodio Freire Agroforestry Pole, Rio Branco - AC
Amazon colonization has been carried out in a disordered way with major environmental impacts and low economic and social returns. Aiming to minimize impacts and growth of periphery of cities, the State of Acre has the Agroforestry Systems (SAF s) as a means of improving rural production and consequently reducing deforestation in the state, seeking equilibri
Publicado em: 2008
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16. Ecossistemas de replicadores: uma abordagem via mecânica estatística de sistemas desordenados / Replicators ecosystems: a statistical mechanics of disordered systems approach
Nesta tese utilizamos o modelo do replicador aleatório, proposto por Diederich e Opper, para analisar as propriedades de equilíbrio de ecossistemas complexos (formados por um grande número de espécies) em três situações distintas. Na primeira parte desta tese, investigamos os efeitos de interações variáveis sobre a estrutura do ecossistema, utiliza
Publicado em: 2007
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17. Valuation of accessibility index through high resolution satellite images and geaographic information systems - a methodological proposal. / Determinação do índice de acessibilidade do município de Osasco/SP pelo uso de imagens de alta resolução espacial e SIG - uma proposta metodológica.
Considering the continuous urban growth, the lack of urban planning produces serious consequences whatever the subject. The accelerated and disordered urban sprawl faced by Brazilian cities since the 1950s has levered serious social and economic problems. In this context, the accessibility measures can be used as one of the several indicators to promote urba
Publicado em: 2007
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18. Phonon spectra of disordered chains: an application to DNA
Recent developments in the field of nano-electronics have encouraged the study of quasi one dimensional systems such as DNA and its applications to new devices. In this work we use two models to explore the vibrational properties of DNA-like chains: a linear chain and two laterally coupled linear chains. In the former case, the disorder induces a diatomic be
Brazilian Journal of Physics. Publicado em: 2006-09
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19. An efficient algorithm to generate random uncorrelated Euclidean distances: the random link model
A disordered medium is often constructed by N random points independently and identically distributed in a d-dimensional hyperspace. Characteristics related to the statistics of this system are known as the random point problem. As d ® ¥, the distances between two points become independent random variables, leading to its mean fiel
Brazilian Journal of Physics. Publicado em: 2006-03
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20. Remanent magnetization in the antiferromagnetic systems / Magnetização remanente em sistemas antiferromagnéticos"
In the context of low anisotropy, the magnetization measurements to find out the magnetic effects induced by the substitution of Mn+2 by Cu+2 íons in the quaseone-dimensional Heisenberg-like antiferromagnets CsMn1-xCuxA3.2H2O (A = Cl,Br) were made. In the diluted samples of the Br derivative, we observe the appearance of a remanent magnetization (Mr) below
Publicado em: 2006
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21. Universality classes of chaotic cellular automata
Cellular automata (CA) are discrete, spatially-homogeneous, locally-interacting dynamical systems of very simple construction, but which exhibit a rich intrinsic behavior. Even starting from disordered initial configurations, CA can evolve into ordered states with complex structures crystallized in space-time patterns. In this paper we concentrate on determi
Brazilian Journal of Physics. Publicado em: 2004-06
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22. PHYSICS OF STRONGLY CORRELATED AND DISORDERED SYSTEMS / FÍSICA DE SISTEMAS FORTEMENTE CORRELACIONADOS E DESORDENADOS
In this thesis we study the properties of strongly correlated and disordered materials, using model Hamiltonians to describe them. The thesis is divided in two parts. The first one studies the periodic Anderson model used to describe the properties of a Kondo insulator. In particular we take Ce3Bi4Pt3 as a paradigmatic compound, characterized by a small gap(
Publicado em: 2004
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23. Model ecosystems with nonlinear interspecies interactions. / Modelos de ecossistemas com interações não lineares.
Neste trabalho investigamos as propriedade estatísticas de um modelo de coevolução de N espécies, sob a perspectiva da dinâmica de replicadores. As interações entre pares de espécies são dadas por variáveis aleatórias independentes, fixas no tempo. As interações são também simétricas, de modo que a dinâmica maximiza uma função de Lyapunov
Publicado em: 2004
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24. Lattice models of disorder with order
This paper describes the use of simple lattice models for studying the properties of structurally disordered systems like glasses and granulates. The models considered have crystalline states as ground states, finite connectivity, and are not subject to constrained evolution rules. After a short review of some of these models, the paper discusses how two par
Brazilian Journal of Physics. Publicado em: 2003-09