@Article{SouzaDomiMendPaga:2015:PlStEx,
               author = "Souza, Vitor Moura Cardoso e Silva and Domingues, Margarete 
                         Oliveira and Mendes J{\'u}nior, Odim and Pagamisse, Aylton",
          affiliation = "{Instituto Nacional de Pesquisas Espaciais (INPE)} and {Instituto 
                         Nacional de Pesquisas Espaciais (INPE)} and {Instituto Nacional de 
                         Pesquisas Espaciais (INPE)} and {Universidade Estadual Paulista 
                         (UNESP)}",
                title = "Plasma Structure Extraction from LASCO Images by the Dual-Tree 
                         Complex Wavelet Transform",
              journal = "Revista Brasileira de Geof{\'{\i}}sica",
                 year = "2015",
               volume = "33",
               number = "1",
                pages = "45--56",
                 note = "{Setores de Atividade: Transporte a{\'e}reo.}",
             keywords = "coronal mass ejection, solar plasma, solar corona images, complex 
                         wavelet transform, space weather, eje{\c{c}}{\~a}o de massa 
                         coronal, plasma solar, imagens da coroa solar, transformada 
                         wavelet complexa, clima espacial.",
             abstract = "Images of the Sun obtained in distinct electromagnetic ranges can 
                         be very useful to investigate electrodynamical processes that 
                         occur in this star. This work analyzes the application of a 
                         two-dimensional version of the Dual-Tree Complex Wavelet Transform 
                         (DTCWT) to highlight physical features in the Large Angle and 
                         Spectrometric Coronograph images. The importance of those features 
                         is that they are related with coronal ejections of magnetized 
                         solar plasma, which can produce geomagnetic disturbances at the 
                         Earth. The DTCWT is a laborious improvement of the well-known 
                         Discrete Wavelet Transform (DWT) with additional properties of 
                         shift invariance, ability to analyze multiple directions for 
                         multidimensional signals, and computationally efficient 
                         algorithms. The multilevel decomposition of an image with the 
                         DTCWT generates complex wavelet coefficients, which are 
                         manipulated for providing a proper visualization of the plasma 
                         structures, highlighting features, and helping further analyses. 
                         The methodology implemented here is of interest to space weather 
                         laboratories and has been shown to be a very useful tool to a 
                         better identification and characterization of the features related 
                         to magnetized plasma phenomena in the solar corona. RESUMO: 
                         Imagens do Sol obtidas em diferentes intervalos do espectro 
                         eletromagn{\'e}tico podem ser bem {\'u}teis na 
                         investiga{\c{c}}{\~a}o de processos eletrodin{\^a}micos que 
                         ocorrem nesta estrela. Este trabalho analisa a 
                         aplica{\c{c}}{\~a}o de uma vers{\~a}o bidimensional da 
                         Transformada Wavelet Complexa de dupla {\'a}rvore (DTCWT) para 
                         destacar caracter{\'{\i}}sticas f{\'{\i}}sicas nas imagens do 
                         Coron{\'o}grafo Espectom{\'e}trico de Angulo Largo (LASCO). A 
                         import{\^a}ncia dessas caracter{\'{\i}}sticas {\'e} que elas 
                         est{\~a}o relacionadas a eje{\c{c}}{\~o}es coronais de plasma 
                         solar magnetizado, que podem produzir perturba{\c{c}}{\~o}es 
                         geomagn{\'e}ticas na Terra. A DTCWT {\'e} um aprimoramento 
                         laborioso da bem conhecida Transformada Wavelet Discreta (DWT), 
                         com propriedades adicionais de: (i) invari{\^a}ncia a 
                         deslocamentos, (ii) habilidade em analisar m{\'u}ltiplas 
                         dire{\c{c}}{\~o}es para sinais multidimensionais, e (iii) 
                         algoritmo computacionalmente eficiente. A decomposi{\c{c}}{\~a}o 
                         multin{\'{\i}}vel de uma imagem com a DTCWT gera coeficientes 
                         wavelets complexos, que s{\~a}o manipulados para prover uma 
                         visualiza{\c{c}}{\~a}o adequada das estruturas de plasmas, 
                         destacando caracter{\'{\i}}sticas, e ajudando nas an{\'a}lises 
                         posteriores. De interesse dos laborat{\'o}rios de Clima Espacial, 
                         a metodologia implementada aqui mostrou-se ser muito {\'u}til 
                         para uma melhor identifica{\c{c}}{\~a}o e 
                         caracteriza{\c{c}}{\~a}o dos fen{\^o}menos de plasmas 
                         magnetizados na coroa solar.",
                 issn = "0102-261X",
                label = "lattes: 4693848330845067 2 MouraDomiMendPaga:2015:PlStEx",
             language = "en",
           targetfile = "1_moura2.pdf",
                  url = "http://sys2.sbgf.org.br/revista/index.php/rbgf/article/view/600",
        urlaccessdate = "03 maio 2024"
}