Forced response analysis of hydroelectric systems

At off-design operating points, Francis turbines develop cavitation vortex rope in the draft tube which may interact with the hydraulic system. Risk resonance assessment by means of eigenmodes computation of the system is usually performed. However, the system response to the excitation source induced by the cavitation vortex rope is not predicted in terms of amplitudes and phase. Only eigenmodes shapes with related frequencies and dampings can be predicted. Besides this modal analysis, the risk resonance assessment can be completed by a forced response analysis. This method allows identifying the contribution of each eigenmode into the system response which depends on the system boundary conditions and the excitation source location. In this paper, a forced response analysis of a Francis turbine hydroelectric power plant including hydraulic system, rotating train, electrical system and control devices is performed. First, the general methodology of the forced response analysis is presented and validated with time domain simulations. Then, analysis of electrical, hydraulic and hydroelectric systems are performed and compared to analyse the influence of control structures on pressure fluctuations induced by cavitation vortex rope

As queimadas na região amazônica e o adoecimento respiratório Ground-clearing fires in the amazon and respiratory disease

A queima de biomassa florestal popularmente conhecida como "queimada" é uma prática recorrente e antiga no país e se caracteriza como um dos principais contribuintes mundiais para a emissão de gases de efeito estufa. Entretanto, a consciência global sobre seus possíveis impactos é relativamente recente. A ocorrência de grandes queimadas no cenário brasileiro e internacional despertou a atenção para o problema, mas as medidas tomadas para prevenir e/ou controlar os incêndios ainda são insuficientes. Na região amazônica, com circunstâncias geográficas e ambientais distintas do resto do país, aliadas a um processo histórico de ocupação do território, o uso do fogo expõe a cada ano, parcelas maiores da população tornando-as vulneráveis aos seus efeitos. Neste contexto, esta revisão não sistemática apresenta os trabalhos desenvolvidos nos últimos cinco anos sobre as queimadas na Amazônia Brasileira e o adoecimento respiratório. Tem como objetivo principal fornecer elementos para gestores e dirigentes ambientais sobre as questões que norteiam os problemas relacionados à queima de biomassa florestal na região amazônica.<br>The intentional burning of forest biomass commonly known as "ground-clearing fires" is an age-old and widespread practice in the country and is seen as a major contributor to global emissions of greenhouse gases. However, global awareness of their potential impact is relatively recent. The occurrence of large ground-clearing fires in the Brazilian and international scenarios drew attention to the problem, but the measures taken to prevent and/or control the fires are still insufficient. In the Amazon region, with distinct geographical and environmental features from the rest of the country, with its historic process of land occupation, every year the ground-clearing fires expose larger portions of the population making them vulnerable to its effects. In this context, this non-systematic review presents the papers written over the past five years about the fires in the Brazilian Amazon and respiratory illness. The main objective is to provide information for managers and leaders on environmental issues about the problems related to biomass burning in the Amazon region

Search for new resonances decaying to a W or Z boson and a Higgs boson in the ℓ+ℓ−bb¯, ℓνbb¯, and νν¯bb¯ channels with pp collisions at s=13 TeV with the ATLAS detector

A search is presented for new resonances decaying to a W or Z boson and a Higgs boson in the ℓ+ℓ−bb¯, ℓνbb¯, and νν¯bb¯ channels in pp collisions at s=13 TeV with the ATLAS detector at the Large Hadron Collider using a total integrated luminosity of 3.2 fb−1. The search is conducted by looking for a localized excess in the WH/ZH invariant or transverse mass distribution. No significant excess is observed, and the results are interpreted in terms of constraints on a simplified model based on a phenomenological Lagrangian of heavy vector triplets