Identificação da mudança de uso da terra usando técnicas de agrupamento de séries temporais de imagens de satélite.

Resumo. A disponibilidade de dados orbitais, aliada à necessidade crescente de monitoramento de grandes extensões e de preservação de regiões ambientalmente sensíveis, gera uma oportunidade para o desenvolvimento/adaptação de métodos computacionais. A fim de gerar informações de avaliação temporal e espacial que possam constituir importante ferramenta de planejamento e de orientação à tomada de decisão para o manejo e conservação destas áreas, o objetivo deste trabalho é propor uma abordagem baseada em métodos de agrupamento de séries de imagens de satélite para auxiliar na análise espaço-temporal da mudança do uso da terra, identificando de forma automática, com alta probabilidade de serem áreas inundáveis, floresta, culturas agrícolas e pastagem em escala regional. Séries temporais de imagens do sensor MODIS com valores dos índices de vegetação NDVI e EVI, do período de 2008/2009 a 2013/2014, foram agrupadas por meio do algoritmo K-means. Para uma avaliação da qualidade dos agrupamentos obtidos foi utilizado o coeficiente de Silhueta. Séries temporais de precipitação do satélite TRMM foram utilizadas a fim de correlacionar com os demais resultados obtidos para avaliar a pré-classificação gerada pelo método de agrupamento em anos secos, chuvosos e com distribuição de chuva diferente da normalidade. A abordagem proposta pode auxiliar no monitoramento de áreas ambientalmente sensíveis, tendo o EVI apresentado melhor desempenho em áreas de densa vegetação e concentração de água.Geopantanal 2014

Mechanical properties and microstructure of VPS and HVOF CoNiCrAlY coatings

HVOF and VPS coatings were sprayed using a Praxair (CO-210-24) CoNiCrAlY powder. Free standing coatings underwent vacuum annealing at different temperatures for times of up to 840h. Feedstock powder, as-sprayed and annealed coatings were characterised by SEM, EDS and XRD. The hardness and Young’s modulus of as-sprayed and annealed HVOF and VPS coatings were measured, including determination of Young’s moduli of the individual phases via nanoindentation and measurement of Young’s moduli of coatings at temperatures up to 500°C. The Eshelby inclusion model was used to investigate the effect of microstructure on the coatings’ mechanical properties. The sensitivity of the mechanical properties to microstructural details was confirmed. Young’s modulus was constant to ~200°C then decreased with increasing measurement temperature. Annealing increased Young’s modulus due to a combination of decreased porosity and β volume fraction. Oxide stringers in the HVOF coating maintained its higher hardness than the VPS coating even after annealing

An overview of using small punch testing for mechanical characterization of MCrAlY bond coats

Considerable work has been carried out on overlay bond coats in the past several decades because of its excellent oxidation resistance and good adhesion between the top coat and superalloy substrate in the thermal barrier coating systems. Previous studies mainly focus on oxidation and diffusion behavior of these coatings. However, the mechanical behavior and the dominant fracture and deformation mechanisms of the overlay bond coats at different temperatures are still under investigation. Direct comparison between individual studies has not yet been achieved due to the fragmentary data on deposition processes, microstructure and, more apparently, the difficulty in accurately measuring the mechanical properties of thin coatings. One of the miniaturized specimen testing methods, small punch testing, appears to have the potential to provide such mechanical property measurements for thin coatings. The purpose of this paper is to give an overview of using small punch testing to evaluate material properties and to summarize the available mechanical properties that include the ductile-to-brittle transition and creep of MCrAlY bond coat alloys, in an attempt to understand the mechanical behavior of MCrAlY coatings over a broad temperature range

Comparison of contrast-enhanced multidetector computed tomography angiography and splenoportography for the evaluation of portosystemic-shunt occlusion after cellophane banding in dogs

BACKGROUND Many patients with a congenital extrahepatic portosystemic shunt (PSS) do not tolerate an immediate shunt closure. Therefore, slow progressive techniques were developed. To evaluate the success of shunt closure diagnostic imaging is essential to identify possible residual blood flow through the shunt vessel. There is a lack of information about the reliability of computed tomography angiography (CTA) for evaluating residual flow through a PSS after treatment. The purpose of this prospective study was to compare the results of CTA with splenoportography. Three months after cellophane banding CTA and splenoportography were performed in 20 dogs and reviewed by three independent examiners, respectively. In both imaging modalities the presences of a residual shunt was judged as present or absent and the extent of visibility of portal vasculature was recorded. RESULTS Based on the evaluation of the splenoportography residual flow through shunt was present in 6 dogs. The classification of residual shunt present or absent showed a substantial to perfect agreement (κ = 0.65-1.00) between the observers in splenoportography and a slight to moderate agreement (κ = 0.11-0.51) for CTA. Sensitivity and specificity varied between 0.50 and 1.00 and 0.57-0.85, respectively. Significant correlation between CTA and splenoportography for the classification of residual shunt was present only in one observer but not in the other two. CONCLUSION More studies were classified as residual shunt positive with CTA compared to splenoportography. It remains unclear which methods do reflect reality better and thus which method is superior. The greater inter-rater agreement for splenoportography suggests a greater reliability of this technique

The representation of the context in the simulation of complex systems

This paper moves from the recognition of the importance of the role of context in determining human action. By context we mean social and cultural properties of an environment as defined by Activity Theory (Kaptelinin, 1996). According to Activity Theory, human beings live in an environment that is meaningful in itself. This environment consists of entities that combine all kinds of objective features, including the culturally determined ones, which, in turn, determine the way people act on these entities. This notion of context is fundamental for understanding the role of artefacts in mediating human action. In the paper, we adopt the Activity Theory framework to reflect upon how to represent “the context” for assessing the impact of new technologies in complex systems like the Air Traffic Control (ATC). Nowadays, the validation of such technologies is mostly performed through the simulation of the operational environment, where controllers perform their activity as if they were in a real situation. In the paper, we describe an experience we made simulating the activity of an air traffic control tower in managing aerodrome traffic. The simulation was carried out using structured scenarios to represent activities really observed in the control tower and adapted to fit the context of simulation (more advanced control tools, subset of controllers working together). These scenarios offered a valid contribution toward the representation of the context in complex systems like ATC. They successfully contributed to recreate realistic situations where the system components were subject to the full variability of input data and situations that may occur in the real world. Through the description and discussion of the case study, we argue that social and cultural properties of the context need to be represented and analysed, as well as the physical and cognitive aspects of the human-system interaction. The analysis of these properties can be beneficial in particular for assessing the impact of the introduction of new technology or the application of new operational concepts on safety