Metodologia da predição estatística a médio prazo para avaliação da conformidade da tensão em circuitos de distribuição secundários.

A Energia elétrica é um produto cada vez mais importante para a população no Brasil e no Mundo. Os órgãos que regulam a qualidade da distribuição de energia no Brasil aplicam severas penalizações às concessionárias que transgridem os níveis aceitáveis de tensão. Em contrapartida, as concessionárias buscam reduzir os seus custos operacionais, ou seja, melhorar o produto fornecido sem fazer maiores investimentos. A utilização de registradores digitais de tensão para o controle dos níveis de tensão é a ferramenta adotada atualmente pela CPFL Paulista para monitorar, controlar e apurar efetivamente em campo os níveis de tensão da rede de distribuição secundária. Para efeito de elaboração de projetos, a mesma dispõe de softwares que fazem as análises de queda de tensão. Contudo, estes softwares não possuem ferramentas para análise dos índices de transgressão dos níveis de tensão, seja em caráter imediato ou a longo prazo. A metodologia proposta não substitui a obrigatoriedade de se executar medições em campo, pelo fato dos consumidores terem formalizado as reclamações de nível de tensão. Contudo, a mesma tem como objetivo planejar a distribuição da tensão ao longo da rede secundária e desta forma, teoricamente, reduzir custos operacionais e de penalizações frente ao fornecimento inadequado de energia elétrica. Diante da escassez de bibliografias sobre o assunto, a metodologia proposta implementa conceitos de curvas de carga, geração de processos aleatórios “Método de Monte Carlo”, utilização da base de dados da concessionária e também os dados de faturamento. Com base nisto foi desenvolvido um algoritmo sobre a plataforma do software Matlab®, onde foi possível implementar uma metodologia que, com base em rotinas de fluxo de potência, é possível identificar as possíveis transgressões que uma determinada rede de distribuição secundária poderá vir a sofrer ao longo dos anos. Para efeito de comparação e validação da metodologia proposta, foi eleito um determinado setor de distribuição secundário onde foram instalados equipamentos de medição para monitorar os níveis de tensão. Avaliada e validada a metodologia, na sequência foram inseridas taxas de crescimento no algoritmo, visando sempre a previsão de possíveis transgressões do setor em análise

Reliability and validity of a questionnaire for physical activity assessment in South American children and adolescents: The SAYCARE Study

ABSTRACT: The objective of this article is to test the reliability and validity of the new and innovative physical activity (PA) questionnaire. Methods: Subsamples from the South American Youth/Child Cardiovascular and Environment Study (SAYCARE) study were included to examine its reliability (children: n 5 161; adolescents: n 5 177) and validity (children: n 5 82; adolescents: n 5 60). The questionnaire consists of three dimensions of PA (lei-sure, active commuting, and school) performed during the last week. To assess its validity, the subjects wore accelerometers for at least 3 days and 8 h/d (at least one weekend day). The reliability was analyzed by correlation coefficients. In addition, Bland-Altman analysis and a multilevel regression were applied to estimate the measurement bias, limits of agreement, and influence of contextual variables. Results: In children, the questionnaire showed consistent reliability (q 5 0.56) and moderate validity (q 5 0.46), and the contextual variable variance explained 43.0% with 222.9 min/d bias. In adolescents, the reliability was higher (q 5 0.76) and the validity was almost excellent (q 5 0.88), with 66.7% of the variance explained by city level with 16.0 min/d PA bias. Conclusions: The SAYCARE PA questionnaire shows acceptable (in children) to strong (in adolescents) reliability and strong validity in the measurement of PA in the pediatric population from low- to middle-income countries

Local hydrological conditions influence tree diversity and composition across the Amazon basin

Tree diversity and composition in Amazonia are known to be strongly determined by the water supplied by precipitation. Nevertheless, within the same climatic regime, water availability is modulated by local topography and soil characteristics (hereafter referred to as local hydrological conditions), varying from saturated and poorly drained to well-drained and potentially dry areas. While these conditions may be expected to influence species distribution, the impacts of local hydrological conditions on tree diversity and composition remain poorly understood at the whole Amazon basin scale. Using a dataset of 443 1-ha non-flooded forest plots distributed across the basin, we investigate how local hydrological conditions influence 1) tree alpha diversity, 2) the community-weighted wood density mean (CWM-wd) – a proxy for hydraulic resistance and 3) tree species composition. We find that the effect of local hydrological conditions on tree diversity depends on climate, being more evident in wetter forests, where diversity increases towards locations with well-drained soils. CWM-wd increased towards better drained soils in Southern and Western Amazonia. Tree species composition changed along local soil hydrological gradients in Central-Eastern, Western and Southern Amazonia, and those changes were correlated with changes in the mean wood density of plots. Our results suggest that local hydrological gradients filter species, influencing the diversity and composition of Amazonian forests. Overall, this study shows that the effect of local hydrological conditions is pervasive, extending over wide Amazonian regions, and reinforces the importance of accounting for local topography and hydrology to better understand the likely response and resilience of forests to increased frequency of extreme climate events and rising temperatures

Mapping density, diversity and species-richness of the Amazon tree flora

Using 2.046 botanically-inventoried tree plots across the largest tropical forest on Earth, we mapped tree species-diversity and tree species-richness at 0.1-degree resolution, and investigated drivers for diversity and richness. Using only location, stratified by forest type, as predictor, our spatial model, to the best of our knowledge, provides the most accurate map of tree diversity in Amazonia to date, explaining approximately 70% of the tree diversity and species-richness. Large soil-forest combinations determine a significant percentage of the variation in tree species-richness and tree alpha-diversity in Amazonian forest-plots. We suggest that the size and fragmentation of these systems drive their large-scale diversity patterns and hence local diversity. A model not using location but cumulative water deficit, tree density, and temperature seasonality explains 47% of the tree species-richness in the terra-firme forest in Amazonia. Over large areas across Amazonia, residuals of this relationship are small and poorly spatially structured, suggesting that much of the residual variation may be local. The Guyana Shield area has consistently negative residuals, showing that this area has lower tree species-richness than expected by our models. We provide extensive plot meta-data, including tree density, tree alpha-diversity and tree species-richness results and gridded maps at 0.1-degree resolution