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Orientadora: Profª. Drª. Roseli Frederigi Benassi / Coorientadora. Profª. Drª. Lucia Helena Gomes Coelho / Dissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Ciência e Tecnologia Ambiental, Santo André, 2018. / Os monitoramentos ambientais de recursos hídricos são construídos por meio de resultados analíticos de variáveis ecológicas que são avaliadas por meio da aquisição de amostras. Estas devem representar o mais fielmente possível as condições e características do ambiente estudado para garantir que as tomadas de decisão baseadas neles sejam adequados. Por conta disso, este trabalho teve como objetivo avaliar a eficiência da utilização do cálculo de incerteza da amostragem como estratégia de garantia da representatividade dos procedimentos de coleta usados em estudos ambientais. Para isso, foram avaliadas amostras, coletadas e analisadas em duplicatas e cujos resultados foram usados para determinar a incerteza da amostragem conforme procedimento definido pelo EURACHEM no documento "Measurement uncertainty arising from sampling". Para tanto, foram avaliados pontos de coleta pertencentes a rede de monitoramento da qualidade das águas superficiais da CETESB, sendo 11 localizados em rios que cruzam a região metropolitana de São Paulo (Pinheiros, Tamanduateí e Tietê) e 9 localizados no reservatório Billings. A população de dados obtidas foi tratada por meio da análise da diferença percentual das duplicatas, para que os valores suspeitos (outliers) fossem excluídos, sendo os resultados escolhidos usados para a determinação incerteza. Por meio do cálculo de incerteza em dois níveis, foram calculadas as incertezas da amostragem e da análise observando-se que a primeira apresentou resultados maiores do que a segunda. Conclui-se, por fim, que apesar da metodologia ser adequada para avaliar o a influência da amostragem e da análise separadamente, o desenho amostral aplicado não permite avaliar as fontes de incerteza presentes em cada ponto, uma vez que considerada pontos com características hidrológicas e limnológicas bastante distintas. / The environmental monitoring of water resources is constructed through analytical results of ecological variables that are evaluated through the acquisition of samples. These should represent as accurately as possible the conditions and characteristics of the environment studied to ensure that decision-making based on them is adequate. The objective of this study is to evaluate the efficiency of the use of the uncertainty calculation of sampling as a strategy to guarantee the representativeness of the collection procedures used in environmental studies. This essay aims to evaluate the efficiency of the uncertainty estimation method as a strategy to ensure representativeness of sampling procedures used in environmental studies. For this, were evaluated the samples, which were collected and analyzed in duplicates and whose results were used to determine the sampling uncertainty according to the procedure defined by EURACHEM in the document "Measurement uncertainty arising from sampling" To that end, collection points belonging to the CETESB surface water quality monitoring network were evaluated, of which 11 were located in rivers crossing the São Paulo metropolitan area (Pinheiros, Tamanduateí and Tietê) and 9 located in the Billings reservoirs. The population of data obtained was treated by means of the analysis of the Percent Difference of the duplicates, so that the outliers were excluded, and the chosen results were used to determine uncertainty. By calculating uncertainty at two levels, we calculated the sampling and analysis uncertainties by observing that the former presented higher than the second results. Finally, it is concluded that although the methodology is adequate to evaluate the influence of sampling and analysis separately, the applied sample design does not allow to evaluate the sources of uncertainty present in each point, once considered points with hydrological and limnological characteristics quite different.

Turbulent boundary layers approximating those found on the NASA Orion Multi-Purpose Crew Vehicle (MPCV) thermal protection system during atmospheric reentry from the International Space Station have been studied by direct numerical simulation, with the ultimate goal of reducing aerothermodynamic heating prediction uncertainty. Simulations were performed using a new, well-verified, openly available Fourier/B-spline pseudospectral code called Suzerain equipped with a ``slow growth'' spatiotemporal homogenization approximation recently developed by Topalian et al. A first study aimed to reduce turbulence-driven heating prediction uncertainty by providing high-quality data suitable for calibrating Reynolds-averaged Navier--Stokes turbulence models to address the atypical boundary layer characteristics found in such reentry problems. The two data sets generated were Ma[approximate symbol] 0.9 and 1.15 homogenized boundary layers possessing Re[subscript theta, approximate symbol] 382 and 531, respectively. Edge-to-wall temperature ratios, T[subscript e]/T[subscript w], were close to 4.15 and wall blowing velocities, v[subscript w, superscript plus symbol]= v[subscript w]/u[subscript tau], were about 8 x 10-3 . The favorable pressure gradients had Pohlhausen parameters between 25 and 42. Skin frictions coefficients around 6 x10-3 and Nusselt numbers under 22 were observed. Near-wall vorticity fluctuations show qualitatively different profiles than observed by Spalart (J. Fluid Mech. 187 (1988)) or Guarini et al. (J. Fluid Mech. 414 (2000)). Small or negative displacement effects are evident. Uncertainty estimates and Favre-averaged equation budgets are provided. A second study aimed to reduce transition-driven uncertainty by determining where on the thermal protection system surface the boundary layer could sustain turbulence. Local boundary layer conditions were extracted from a laminar flow solution over the MPCV which included the bow shock, aerothermochemistry, heat shield surface curvature, and ablation. That information, as a function of leeward distance from the stagnation point, was approximated by Re[subscript theta], Ma[subscript e], [mathematical equation], v[subscript w, superscript plus sign], and T[subscript e]/T[subscript w] along with perfect gas assumptions. Homogenized turbulent boundary layers were initialized at those local conditions and evolved until either stationarity, implying the conditions could sustain turbulence, or relaminarization, implying the conditions could not. Fully turbulent fields relaminarized subject to conditions 4.134 m and 3.199 m leeward of the stagnation point. However, different initial conditions produced long-lived fluctuations at leeward position 2.299 m. Locations more than 1.389 m leeward of the stagnation point are predicted to sustain turbulence in this scenario. / text