Resumo: A oferta de metodologias de modelagem de processos de negócios é bastante extensa, dificultando os estudiosos da área de BPM uma escolha adequada. Nesse contexto, este artigo tem o objetivo de apresentar as principais metodologias de modelagem, com aplicações, exemplos e comparações. Foi realizado um levantamento sistemático bibliográfico e análise comparativa dessas notações utilizadas na implementação de projetos BPM. De acordo com a análise bibliométrica, as notações de modelagem de processos de negócio mais retratadas nos trabalhos levantados são: BPMN, UML, EPC e IDEF. A partir da construção de um overview consistente que permita a análise comparativa das metodologias, a fim de selecionar aquela que mais se adequa às suas especificidades pode-se verificar que, embora partilhem o mesmo objetivo, cada notação tem as suas características específicas. Este estudo possui propósito principal de servir de base para a indicação adequada a aplicação de estudos na área, em especial aos destinados a papers, dissertações e teses.

Abstract The offer of business process modeling methodologies is quite extensive, making it difficult for scholars in the BPM area to choose properly. In this context, this paper has the objective to present the main modeling methodologies, with applications, examples and comparisons. A systematic bibliographic survey and the comparative analysis of these notations used in the implementation of BPM projects have been carried out. According to the bibliometric analysis, the modeling notations of the business process most portrayed in the works surveyed are: BPMN, UML, EPC and IDEF. From the construction of a consistent overview that allows the comparative analysis of the methodologies, in order to select the one that suits better its specificities it can be verified that, although they share the same objective, each notation has its specific characteristics. This study has the main purpose of providing a basis for the adequate indication of the application of studies in the field, especially those destined for papers, dissertations and theses.

U-xZr-yNb alloys with values of x varying from 32% to 50% (wt.%Zr) and y varying from 6% to 10% (wt.%Nb) were produced by the arc melting technique. The effect of the addiction of zirconium and niobium on the phase stabilization of γ-U, lattice parameter, microstructure and elemental composition were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscope (EDS) techniques. The alloys crystallized in a cubic symmetry composed by a γ-U(Zr,Nb) matrix and β-Zr small precipitates, when the content of zirconium and niobium is up to 55 wt.%. With further additions, e.g. 60 wt.%, was observed a highly enriched macrosegregation of β-Zr. It was also observed that the cell size of the γ-U(Zr,Nb) phase increase with the addition of Zr and Nb. The lattice parameter curve behavior as a function of zirconium and niobium deviates from a linear behavior at around x ≈ 50 and y ≈ 10 wt.%.

ABSTRACT Environmental considerations in addition to technical, economical and societal benefits are increasingly promoting the substitution of natural fibers for glass fiber in polymer matrix composites. However, natural fibers are heterogeneous in their dimensions, specially the cross section, which plays an important role in their mechanical strength. It has been found that the equivalent diameter of fibers such as sisal, ramie, pineapple and curaua correlates to different levels of tensile resistance. Piassava is a promising stiff natural fiber for composite reinforcement. In this work, a statistical analysis of tensile strength of piassava fibers using the Weibull methodology was performed. An attempt to correlate the fiber strength, obtained in tensile tests, with the diameter, precisely measured by means of a profile projector, was carried out. The results revealed an inverse dependence between the piassava fiber diameter and corresponding tensile strength. Fracture tip observation by SEM suggested a possible mechanism that could justify this inverse correlation.

ABSTRACT Polymer matrix composites have been applied in components such as helmets and shielding for which toughness is a major requirement. Natural fiber presents interfacial characteristics with polymeric matrices that favor a high impact energy absorption by the composite structure. The objective of this work was then to assess the Izod impact resistance of polymeric composites reinforced with different amounts, up to 30% in volume, of a promising high strength natural fiber from the Amazon region known as curaua. Among these, the piassava fiber extracted from a palm tree native of South America stands as one of the most rigid with a potential to be used as composite reinforcement. Therefore, the present work investigates the notch toughness behavior, by Izod impact tests, of epoxy composites reinforced with up to 40 % in volume of continuous and aligned piassava fibers.The results showed a remarkable increase in the notch toughness with the amount of incorporated curaua fibers. This can be attributed to a preferential debonding of the fiber/matrix interface, which contributes to an elevated absorbed energy. . It was found that the incorporation of piassava fibers results in significant increase in the impact energy of the composite. Scanning electron microscopy analysis showed that the nature of the piassava fiber interface with the epoxy matrix is the major responsible for the superior toughness of the composite.

A nanostructured Cr11Ge19 phase was produced by mechanical alloying for 15 h. Decomposition occurred for larger milling times, yielding Cr, Ge, Cr2O3 and GeO2. According to the Cr-Ge phase diagram, the Cr11Ge19 phase is stable up to ≈ 928 oC, but, when submitted to milling, a structural instability causes its decomposition. We studied this structural instability using the coordination numbers and interatomic distances of bulk Cr11Ge19 to simulate the structure factors SCrCr(K), SCrGe(K), and SGeGe(K). The radial distribution functions RDFCrCr(R), RDFCrGe(R) and RDFGeGe(R) were obtained by Fourier transforming the Sij(K) factors, and an important chemical disorder up to ≈7 Å was observed in the RDFCrGe(R) and RDFGeGe(R) functions. This chemical disorder was quantified using Cowley-Warren α ij CW parameter. The thermoelectric properties of the Cr11Ge19 phase were also studied.

Natural fibers obtained from cellulose-based plants are being used as reinforcement of polymer composite owing to both environmental and technical advantages. One important technical characteristic of most lignocellulosic fibers is the bend flexibility, which allows them to resist impact forces. As a consequence, there is an increasing application of these lignocellulosic fibers in automobile parts that, during a crash event, should absorb the impact energy without splitting into sharp pieces. The present work investigates the toughness behavior of polyester composites reinforced with up to 30% in volume of alkali treated continuous and aligned curaua fibers by means of Charpy impact tests. It was found that the incorporation of treated curaua fibers increased the composite absorbed impact energy but not as much as in composites reinforced with non-treated fibers. Macroscopic observation, and scanning electron microscopy analysis of fracture surface, revealed that the main mechanism for the increase in the Charpy notch toughness is the interfacial rupture between the curaua fiber and the polyester matrix.