Numerical calculation of varistor model for sinusoidal signal

ZnO varistors are semiconductor devices with highly nonlinear current-voltage characteristic and are widely used as devices for overvoltage protection. Varistor applications range from the use of small varistors to protect electronic components to large varistors for protection of power systems. This paper presents proposed model of ZnO varistor and methodology of its mathematical analysis and simulation. The mathematical analysis of the proposed model makes it possible simulate the current trace on a nonlinear element

Neural networks for real-time estimation of parameters of signals in power systems

Fast determination of parameters of the fundamental waveform of voltages and currents is essential for the control and protection of electrical power systems. Most of the known digital algorithms are not fully parallel, so that the speed of processing is quite limited. New parallel algorithms, which can be implemented by analogue adaptive circuits employing some neural networks principles, are proposed. The problem of estimation is formulated as an optimization problem and solved by using the gradient descent method. Algorithms based on the least absolute value, the minimax, the least-squares and the robust leastsquares criteria are developed and compared. The networks process samples of observed noisy signals (voltages or currents) and give as a solution the desired parameters of signal components. Extensive computer simulations confirm the validity and performance of the proposed algorithms and neural network realizations. The proposed methods seem to be particularly useful for real-time, high-speed estimation of parameters of sinusoidal signals in electrical power systems

Water safety plans and climate change mitigation

[Excerpt] Definition Quality water at affordable prices for all is a key condition for the promotion of public health, environmental sustainability, and quality and safety of life. In a context of growing external uncertainties arising from changes in the climate and the environment, ensuring these conditions is an upward concern and is of utmost relevance to increase scientific research on the impacts of climate change on water quality modification and in minimization/mitigation strategies

Temporal and thematic trends in water, sanitation and hygiene (WaSH) research in Pacific Island Countries: a systematic review

Pacific Island Countries (PICs) lag behind global trends in water, sanitation and hygiene (WaSH) development. We conducted a systematic search of all English language papers (published before February 2015) about WaSH in PICs to evaluate the state of the peer-reviewed literature and explore thematic findings. A total of 121 papers met the criteria for full-text review following an initial search result of more than 6,000 papers. Two reviewers independently assessed the quality and relevance of each article and consolidated their findings according to four emergent themes: public health, environment, emergency response and interventions, and management and governance. Findings indicate a knowledge gap in evidence-guided WaSH management strategies that advocate for human health while concurrently protecting and preserving drinking water resources. Extreme weather events threaten the quantity and quality of limited freshwater resources, and cultural factors that are unique to PICs present challenges to hygiene and sanitation. This review highlights the strengths and weaknesses of the peer-reviewed literature on WaSH in PICs, addresses spatial and temporal publication trends, and suggests areas in need of further research to help PICs meet development goals

On-plot drinking water supplies and health: a systematic review

Many studies have found that household access to water supplies near to or on the household plot can reduce the probability of diarrhea, trachoma, and other water-related diseases, and it is generally accepted that on-plot water supplies produce health benefits for households. However, the collective body of research literature has not been analyzed to weigh the evidence supporting this. A systematic literature review was conducted to investigate the impacts of on-plot water supplies on diarrhea, trachoma, child growth, and water-related diseases, to further examine the relationship between household health and distance to water source and to assess whether on-plot water supplies generate health gains for households. Studies provide evidence that households with on-plot water supplies experience fewer diarrheal and helminth infections and greater child height. Findings suggest that water-washed diseases are more strongly impacted by on-plot water access than waterborne diseases. Few studies analyzed the effects of on-plot water access on quantity of domestic water used, hygiene behavior, and use of multiple water sources, and the lack of evidence for these relationships reveals an important gap in current literature. The review findings indicate that on-plot water access is a useful health indicator and benchmark for the progressive realization of the Sustainable Development Goal target of universal safe water access as well as the human right to safe water

Advancing methods for research on household water insecurity: Studying entitlements and capabilities, socio-cultural dynamics, and political processes, institutions and governance

© 2017 Elsevier B.V. Household water insecurity has serious implications for the health, livelihoods and wellbeing of people around the world. Existing methods to assess the state of household water insecurity focus largely on water quality, quantity or adequacy, source or reliability, and affordability. These methods have significant advantages in terms of their simplicity and comparability, but are widely recognized to oversimplify and underestimate the global burden of household water insecurity. In contrast, a broader definition of household water insecurity should include entitlements and human capabilities, socio-cultural dynamics, and political institutions and processes. This paper proposes a mix of qualitative and quantitative methods that can be widely adopted across cultural, geographic, and demographic contexts to assess hard-to-measure dimensions of household water insecurity. In doing so, it critically evaluates existing methods for assessing household water insecurity and suggests ways in which methodological innovations advance a broader definition of household water insecurity

Adaptacyjne sieci neuronowe w zastosowaniu do identyfikacji stanu układów elektrycznych

Celem pracy jest zbadanie możliwości zastosowania sieci neuronowych do estymacji parametrów sygnałów w czasie rzeczywistym, których adaptacyjny algorytm działania oparty jest na nowych kryteriach TLS i RTLS oraz zbadanie możliwości zastosowania wybranych układów sieci neuronowych do identyfikacji stanu pracy niektórych układów elektrycznych. T e z a p r a c y: Adaptacyjne sieci neuronowe umożliwiają dokładniejszą oraz szybszą identyfikację niektórych stanów pracy układów elektrycznych, aniżeli dotychczas stosowane metody

Numerical calculation of varistor model for sinusoidal signal

ZnO varistors are semiconductor devices with highly nonlinear current-voltage characteristic and are widely used as devices for overvoltage protection. Varistor applications range from the use of small varistors to protect electronic components to large varistors for protection of power systems. This paper presents proposed model of ZnO varistor and methodology of its mathematical analysis and simulation. The mathematical analysis of the proposed model makes it possible simulate the current trace on a nonlinear element

Artificial Neural Network for Real-Time Estimation of Basic Parameter of Signals

This paper presents for students instructions to using parallel algorithms, which can be implemented by analogue adaptive circuits employing some neural networks principles for estimation of parameters of signals in power system. Algorithms based on the standard least-squares (LS) criteria is proposed. The problem of estimation is formulated as an optimization problem and solved by using the gradient descent optimization algorithm. The corresponding architectures of analogue neuron-like adaptive processors are also shown