Abstract This article presents the theoretical analysis of a signal coupling between a proposed Photonic Crystal Fiber (PCF) and a Conventional Fiber with Step Index (CFSI) system. In this analysis, the Finite Element Method (FEM) and Beam Propagation Method (BPM) are applied together with Daubechies wavelets as basis function and described in the mathematical formulation. The simulations were performed casting the PCF signal into CFSI core using the PCF refractive index. For simulation purposes, the cladding material refractive index was set as 1.5% lower than the core index. The application of Daubechies wavelets as basis functions in BPM analysis presented insertion loss around 3.8% during the fiber coupling.

Resumo O objetivo deste estudo foi caracterizar e avaliar as propriedades físicas e mecânicas de uma zircônia experimental para aplicação odontológica e comparar os resultados da resistência à flexão biaxial com a simulação de elementos finitos (MEF). Amostras de zircônia tetragonal estabilizada com ítria (Y-TZP) foram sinterizadas a 1475 °C/2 h e caracterizadas por difração de raios X, microscopia eletrônica de varredura, densidade relativa, resistência à flexão usando teste de pistão em três bolas (P-3B) e módulo de Young. A partir dos resultados de resistência à flexão, foram realizadas simulações numéricas utilizando o software Abaqus. O modelo completo utilizou 70216 elementos. Os resultados apontaram para densificação total em amostras sinterizadas, ZrO2 tetragonal e cúbica como fases cristalinas, tamanho de grão de 0,6±0,2 μm, módulo de Young de 195±4 GPa, resistência à flexão de 1191±9 MPa e módulo de Weibull m=16,3. A simulação numérica indicou uma resistência à flexão próxima de 1100 MPa, com diferença menor que 7% em relação aos resultados experimentais. Os resultados foram comparados associando as propriedades físicas e mecânicas de Y-TZP com seus fenômenos intrínsecos, como a transformação tgm e o domínio ferroelástico.

Abstract The objectives of this study were to characterize and evaluate the physical and mechanical properties of an experimental zirconia for dental application and compare the biaxial flexural strength results with the finite element simulation (FEM). Yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) ceramic samples were sintered at 1475 °C/2 h and characterized by X-ray diffraction, scanning electron microscopy, relative density, flexural strength using piston-on-three balls (P-3B) test and Young’s modulus. From the flexural strength results, numerical simulations were performed using Abaqus software. The complete model used 70216 elements, considering the components of the test. The results indicated full densification of sintered samples, ZrO2-tetragonal and ZrO2-cubic as crystalline phases, and average grain size of 0.6±0.2 μm. Mechanical characterization of sintered samples indicated Young’s modulus of 195±4 GPa, flexural strength of 1191±9 MPa and Weibull modulus m=16.3. FEM simulation indicated a flexural strength close to 1100 MPa, with a difference lower than 7% in relation to the experimental results. The results were compared associating the physical and mechanical properties of Y-TZP with its intrinsic phenomena such as tgm transformation and ferroelastic domain.

We investigate solutions, by using the Green function approach, for a system governed by a non-Markovian Fokker-Planck equation and subjected to a Comb structure. This structure consists of the axis of structure as the backbone and fingers which are attached perpendicular to the axis. For this system, we consider an arbitrary initial condition, in the presence of time dependent diffusion coefficients and spatial fractional derivative, and analyze the connection to the anomalous diffusion.

O solo aluvial da Ilha de Assunção, localizada no Rio São Francisco, em Cabrobó (PE), tem sido intensamente cultivado com culturas anuais sob irrigação. O nível de produtividade atual não é satisfatório em razão do uso de práticas agrícolas inadequadas para a continuidade da atividade agrícola. Objetivou-se realizar um levantamento das propriedades químicas dos solos numa área de 1.131 ha, por meio da coleta de 1.053 amostras de solo, na profundidade de 0-30 cm. As amostras foram caracterizadas quimicamente e os dados analisados por técnicas estatísticas descritivas. Os resultados obtidos indicaram haver maior variabilidade para os teores de alumínio, potássio, fósforo e para a percentagem de saturação por sódio e menor variabilidade para pH, não havendo distribuição normal dos dados. As amostras de solo apresentaram, em sua maioria, baixos teores de alumínio, de matéria orgânica e de fósforo; valores de pH e CTC e teores de cálcio + magnésio e potássio adequados para a maioria das culturas e foram classificadas como normais em relação à percentagem de saturação por sódio.

The alluvial soil of the Assunção Island, in the São Francisco River, Cabrobó, State of Pernambuco, Brazil, has been intensively cultivated with annual crops under irrigation. The present yields are unsatisfactory due to the use of inadequate agricultural practices that are not sustainable. This study aimed to survey the soil chemical properties in an area of 1,131 ha by collecting 1,053 samples in the 0-0.30 m surface soil layer. The samples were analyzed for chemical properties and the data were analyzed using descriptive statistics. The obtained results indicated that there was higher variability for aluminum, potassium and phosphorus concentration and for the percentage of sodium saturation. The lowest variability was observed for soil pH. The data did not present a normal distribution. Most soil samples presented low aluminum, organic matter, and phosphorus concentrations. The soil pH, CEC, calcium, magnesium, and potassium concentration were interpreted as appropriate for most crops and were classified as normal regarding the percentage of sodium saturation.

A method for obtaining critical properties of physical systems is presented. Based on a recursive relation involving a physical parameter of the system, it drives the system spontaneously to the critical point, providing an efficient way to estimate critical properties. The method is illustrated for several ferromagnetic Ising systems on well-known Bravais lattices. A finite-size scaling approach is performed, by applying the method on lattices of different sizes. The efficiency of the method is confirmed by evaluating critical temperatures, as well as critical exponents, that turn up to be in good agreement with those available in the literature, with a relatively small computational effort.