Geometry, dynamics and fractals

Bevilácqua, Luiz; Barros, Marcelo Miranda; Galeão, Augusto.C.R.N.

doi:10.1590/s1678-58782008000100003

Cited by 10 publications

(8 citation statements)

References 6 publications

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“…An improvement to our seep-spill discrimination process could be the use of other variables to start the analysis. We suggest exploring the dynamic fractal [81], ratios accounting for the SAR signals inside and outside of the oil slicks to standardize for the wind influence [28], gapped pixel space from transect lines through the oil slicks [82], etc. These new attributes could bring further information to our capacity to differentiate the slick category.…”

Section: Recommendations For Future Workmentioning

confidence: 99%

Oil-Slick Category Discrimination (Seeps vs. Spills): A Linear Discriminant Analysis Using RADARSAT-2 Backscatter Coefficients (σ°, β°, and γ°) in Campeche Bay (Gulf of Mexico)

et al. 2019

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A novel empirical approach to categorize oil slicks’ sea surface expressions in synthetic aperture radar (SAR) measurements into oil seeps or oil spills is investigated, contributing both to academic remote sensing research and to practical applications for the petroleum industry. We use linear discriminant analysis (LDA) to try accuracy improvements from our previously published methods of discriminating seeps from spills that achieved ~70% of overall accuracy. Analyzing 244 RADARSAT-2 scenes containing 4562 slicks observed in Campeche Bay (Gulf of Mexico), our exploratory data analysis evaluates the impact of 61 combinations of SAR backscatter coefficients (σ°, β°, γ°), SAR calibrated products (received radar beam given in amplitude or decibel, with or without a despeckle filter), and data transformations (none, cube root, log10). The LDA ability to discriminate the oil-slick category is rather independent of backscatter coefficients and calibrated products, but influenced by data transformations. The combination of attributes plays a role in the discrimination; combining oil-slicks’ size and SAR information is more effective. We have simplified our analyses using fewer attributes to reach accuracies comparable to those of our earlier studies, and we suggest using other multivariate data analyses—cubist or random forest—to attempt to further improve oil-slick category discrimination.

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Section: Recommendations For Future Workmentioning

confidence: 99%

Oil-Slick Category Discrimination (Seeps vs. Spills): A Linear Discriminant Analysis Using RADARSAT-2 Backscatter Coefficients (σ°, β°, and γ°) in Campeche Bay (Gulf of Mexico)

et al. 2019

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“…The technique proposed in a series of papers [Bevilacqua and Barros 2007;Bevilacqua et al 2008] is applied here to mixed structures. The results reproduce the expected output of the method.…”

Section: Discussionmentioning

confidence: 99%

“…Following the same technique exposed before build a spring-mass system using a folded wire with the same shape as the reference term carrying a mass m at one of the extremities and keeping the other clamped ( Figure 5, left). It is possible, as already discussed [Bevilacqua et al 2008] to find three fundamental frequencies corresponding to three selected excitation introduced by a horizontal force H , a vertical force V and a concentrated moment M.…”

Section: (K)mentioning

confidence: 97%

“…Namely, the periods of a sequence of simple oscillators associated to a given Koch sequence have been successfully used to determine the geometric fractal dimension of the given sequence [Bevilacqua et al 2008]. We present below the more important results obtained for Koch curves that will help to understand the numerical approach used here to deal with complex curves as explained later on.…”

Section: Introductionmentioning

confidence: 99%

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Dynamical characterization of mixed fractal structures

Bevilácqua

Barros

2011

J. Mech. Mater. Struct.

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It is because of people like Marie-Louise and Charles that it is worth fighting for a better world.We present a new technique to determine the fractal or self-similarity dimension of a sequence of curves. The geometric characterization of the sequence is obtained from the mechanical properties of harmonic oscillators with the same shape of the terms composing the given sequence of curves. The definition of "dynamical dimension" is briefly introduced with the help of simple examples. The theory is proved to be valid for a particular type of curves as those of the Koch family. The method is applied to more complex plane curves obtained by superposing two generators of the Koch family with different fractal dimensions. It is shown that this structure is composed by two series of objects one of which is fractal and the other which is not rigorously a fractal sequence but approaches asymptotically a fractal object. The notion of quasifractal structures is introduced. The results are shown to provide good information about the structure formation. It is shown that the dynamical dimension can identify randomness for certain fractal curves.

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“…Os efeitos da fragmentação e a criação de um grande número de áreas internas podem ser entendidos, a partir da complexidade da estrutura geométrica dos fragmentos na paisagem, que se comportam como fractais (BEVILACQUA et al, 2008), as áreas que se separaram com a simulação da borda estão representadas por apêndices, os quais Houaiss (2009) define como parte pertencente a outra maior e que a completa. Esses apêndices numericamente crescem ou desaparecem, a partir da fragmentação e seu respectivo efeito de borda.…”

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Avaliação Da Cobertura Florestal Na Paisagem De Mata Atlântica No Ano De 2010, Na Região De Ouro Preto - Mg

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Pereira

Barros

et al. 2015

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RESUMO:Objetivou-se, neste trabalho, avaliar o estado de conservação atual da paisagem na região de Ouro Preto, Ouro Branco e Mariana, MG, correspondendo à áreas situadas no alto das bacias dos rios das Velhas, do Carmo, Gualaxo do Sul e ribeirão da Colônia. A região possui diferentes Unidades de Conservação (UCs), localizadas no domínio fitogeográfico da Mata Atlântica. Utilizaram-se imagens RapidEye AG (jun/2010) com 5 m de resolução espacial. A classificação do uso do solo para obtenção das métricas da paisagem foi dividida em três classes: Floresta Estacional Semidecidual Montana, Vegetação natural 2 e Uso Antrópico. Os resultados apontaram que a área de estudo encontra-se bem preservada, principalmente dentro das UCs, onde se localizam os grandes fragmentos, principais para a conservação; as formações naturais presentes na área de estudos corresponderam a 87,08%; as métricas mostraram que a distância média entre os fragmentos (262) é 72,18 m; a forma e o efeito de bordas nos fragmentos apresentaram-se adversas à preservação da biodiversidade; fortes pressões antrópicas: área urbana, solo exposto, minerações etc., estão presentes em maior intensidade fora da Zona de Amortecimento (ZA) do Parque Estadual do Itacolomi; pontos vulneráveis à conservação encontram-se, em grande parte, próximos às áreas de pastoreio e de mineração, com destaque para as áreas de campo das UCs de Ouro Branco e de pastoreio dentro da APA Estadual Cachoeira das Andorinhas. FOREST COVER EVALUATION IN THE ATLANTIC FOREST LANDSCAPE OF THE OURO PRETO REGION -MG, IN THE YEAR 2010ABSTRACT: This study aimed to evaluate the current state of conservation and the landscape connectivity in the area covering part of the counties of Ouro Preto, Mariana and Ouro Branco, MG. This area is located at the upper course of the Velhas river, Carmo river, Gualaxo do Sul river and Colônia creek. The region belongs to the Mata Atlantica phytogeographic ecosystem and encompasses different Conservation Units (CUs). RapidEye AG (Jun/2010) with 5 m of spatial resolution images were used. The study area was divided into three classes: Seasonal semideciduous montane forest; Natural vegetation 2; Anthropic use. The results showed that the study area is well preserved, particularly inside the CUs where the fragments are bigger and are considered priority sites for conservation. The natural formations of the region corresponded to 87.08% of the study area. The metrics showed that the average distance between the 262 fragments is 72.18 m. The shape of the fragments do not favor the preservation of biodiversity, because they are complex and irregular (fractal). The application of edge effects initially increases the fragmentation and, subsequently reduces the size of individual vegetation spots, smoothing their complex shapes. Strong anthropic pressures are present outside the buffer zone of the State Park of Itacolomi. The weak points are those surrounding pastoral and mining areas, mainly field areas of CUs in Ouro Branco and pasture areas inside the Cachoeira das An...

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Geometry, dynamics and fractals

Abstract: Geometry, Dynamics and Fractals Consider a collection of elastic wires folded according to a given pattern induced by

Cited by 10 publications

References 6 publications

Oil-Slick Category Discrimination (Seeps vs. Spills): A Linear Discriminant Analysis Using RADARSAT-2 Backscatter Coefficients (σ°, β°, and γ°) in Campeche Bay (Gulf of Mexico)

Oil-Slick Category Discrimination (Seeps vs. Spills): A Linear Discriminant Analysis Using RADARSAT-2 Backscatter Coefficients (σ°, β°, and γ°) in Campeche Bay (Gulf of Mexico)

Dynamical characterization of mixed fractal structures

Avaliação Da Cobertura Florestal Na Paisagem De Mata Atlântica No Ano De 2010, Na Região De Ouro Preto - Mg

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