A Hybrid Grey Prediction Model for Small Oscillation Sequence Based on Information Decomposition

Grey prediction model has good performance in solving small data problem, and has been widely used in various research fields. However, when the data show oscillation characteristic, the effect of grey prediction model performs poor. To this end, a new method was proposed to solve the problem of modelling small data oscillation sequence with grey prediction model. Based on the idea of information decomposition, the new method employed grey prediction model to capture the trend characteristic of complex system, and ARMA model was applied to describe the random oscillation characteristic of the system. Crops disaster area in China was selected as a case study and the relevant historical eight-year data published by government department were substituted to the proposed model. The modelling results of the new model were compared with those of other traditional mainstream prediction models. The results showed that the new model had evidently superior performance. It indicated that the proposed model will contribute to solve small oscillation problems and have positive significance for improving the applicability of grey prediction model.

TERRAÇO MARINHO ENTRE BARREIRAS DE BAIXO E TIBAU: ASPECTOS GENÉTICOS E MORFOLÓGICOS

Os terraços marinhos são importantes indicadores de progradação sedimentar em resposta a queda do nível de base/mar. A área de estudo no município de Icapuí é delimitada entre Barreiras de Baixo e Tibau, com o objetivo de analisar as unidades morfológicas associadas a um terraço marinho, além da proposta preliminar de um modelo genético holocênico. Utilizou-se de Ortofotos e Lidar adquiridas junto a Superintendência Estadual do Meio Ambiente do Ceará (SEMACE), a partir destes dados foram gerados perfis topográficos, tridimensionais e classificação de unidades geomorfológicas. O terraço marinho apresentou duas orientações principais: NW-SE e NNW-SSE. Sendo que o primeiro possui as maiores extensões, menores cotas topográficas, maior penetratividade da maré e grande presença das cristas de praia (beach ridges). O segundo setor é caracterizado pela grande presença de campos de dunas. Foi apontado 5 fases evolutivas para a gênese do terraço marinho, considerando as curvas de Bezerra et al., (2003) e Caldas et al., (2006). O Holoceno Superior é nitidamente caracterizado pela queda do nível do mar que pode ter favorecido a progradação das cristas de praia. Destaca-se que no setor mais extenso do terraço (~3,2km) são verificadas algumas ilhas barreiras isoladas, o que pode denotar uma pequena oscilação neste setor.Palavras-chave: Cristas de Praia; Progradação Sedimentar; Variação do Nível do Mar. ABSTRACTMarine terraces are important deposits of sedimentary progradation in response to sea level fall. The study area is delimited between Barreiras de Baixo and Tibau. It presented the aim of analyzing the morphological units associated to a marine terrace, in addition to the preliminary Holocene genetic model. Topographic, three-dimensional profiles and classification of geomorphological units were obtained from Ortofotos e Lidar, acquired in the SEMACE. The marine terrace showed two major orientations: NW-SE and NNW-SSE. The first has the greater width, smaller topographic level, greater influence of the tide and great presence of beach ridges. The second sector is characterized by the great presence of dune fields. Five evolutionary phases of the sea terrace were identified, considering the curves of Bezerra et al. (2003) and Caldas et al. (2006). The Upper Holocene is clearly characterized by sea level drop that may have favored the beach ridges progradation. It is noteworthy that in the larger sector of the terrace (~ 3.2km) there are some isolated barrier islands, which may indicate a small oscillation in this sector.Key-words: Beach Ridges; Sedimentary Progradation; Sea-Level Changes. RESUMENLas terrazas marinas son indicadores importantes de la progradación sedimentaria en respuesta a la caída en la base/nivel del mar. El área de estudio en el municipio de Icapuí está delimitada entre Barreiras de Baixo y Tibau y presenta el objetivo de analizar las unidades morfológicas asociadas a una terraza marina, además de la propuesta preliminar de un modelo genético del Holoceno. Se utilizó Ortofotos y Lidar adquiridos del Superintendência Estadual do Meio Ambiente do Ceará (SEMACE), a partir de estos datos se generaron perfiles topográficos, tridimensionales y clasificación de unidades geomorfológicas. La terraza marina tiene dos orientaciones principales: NO-SE y NNO-SSE. El primero tiene las extensiones más grandes, las dimensiones topográficas más bajas, la mayor penetración de la marea y la gran presencia de crestas de playa. El segundo sector se caracteriza por la gran presencia de campos de dunas. Se identificaron cinco fases evolutivas para la génesis de la terraza marina, considerando las curvas de Bezerra et al. (2003) y Caldas et al. (2006). El Holoceno Superior se caracteriza claramente por la caída del nivel del mar que puede haber favorecido la progradación de las crestas de las playas. Es de destacar que en el sector más grande de la terraza (~ 3.2 km) hay algunas islas de barrera aisladas, lo que puede indicar una pequeña oscilación en este sector.Palabras clave: Crestas de playa; Progradación sedimentaria; Variación del nivel del mar.

HAUSDORFF DIMENSION OF JULIA SETS OF QUADRATIC POLYNOMIALS

The Hausdorff dimension of Julia sets of expanding maps can be computed by the eigenvalue algorithm. In this work, an implementation of this algorithm for quadratic polynomial, that allows the calculation of the Hausdorff dimension of Julia sets for complex parameters, is done. In particular, the parameters in a neighborhood of the parabolic parameter [Formula: see text] are analyzed and a small oscillation in Hausdorff dimension is shown.

Chaotic mixing by oscillating a Stokeslet in a circular Hele-Shaw microfluidic device

Chaotic mixing by oscillating a Stokeslet in a circular Hele-Shaw microffluidic device is presented in this article. Mathematical modeling for the induced flow motions by moving a Stokeslet along the x-axis is derived using Fourier expansion method. The solution is formulated in terms of the velocity stream function. The model is then used to explore different stirring dynamics as function of the Stokeslet parameters. For instance, the effects of using various oscillation amplitudes and force strengths are investigated. Mixing patterns using Poincaré maps are obtained numerically and have been used to characterize the mixing efficiency. Results have shown that, for a given Stokeslet’s strength, efficient mixing can be obtained when small oscillation amplitudes are used. The present mixing platform is expected to be useful for many of biomicrofluidic applications.