Hydro-Québec

About: Hydro-Québec is a government organization based out in Montreal, Quebec, Canada. It is known for research contribution in the topics: Electric power system & Dielectric. The organization has 2596 authors who have published 4433 publications receiving 100878 citations.

Improving Daily Reservoir Inflow Forecasts with Model Combination

Abstract: A major issue in real-time management of water resources is the need for accurate and reliable hydrologic forecasts at least 24 or 48 h ahead. An experiment on improving the accuracy of a conceptual hydrologic model used for daily reservoir inflow forecasting, by resorting to model combination, is presented. A robust weighted-average method is used to take advantage of three dynamically different models: a nearest-neighbor model, a conceptual model, and an artificial neural network model. At each time step, the output of each of these three models is computed, and either the absolute best result is considered or the competitive results are combined using the improved weighted-average method. The latter approach has shown a significant forecast improvement for up to 4-day-ahead prediction. Moreover, it is found that with the model combination, there is no need for postcorrection of the conceptual model forecasts. It is also found that the prediction accuracy is mainly driven by the nearest-neighbor method for the 2-day-ahead forecasts, and relatively by each model afterwards. However, none of the three models appears significantly better than the combined model approach, whatever the prediction lead time.

Characterization of epoxy microcomposite and nanocomposite materials for power engineering applications

Abstract: This article presents the results from round-robin tests performed on epoxy composite materials. These results show the potential of these materials for use as electrical insulation in some specific applications. A small section of the article addresses the health and safety issues related to the use of nanoparticles in the electrical power engineering industry. We define epoxy nanocomposites as epoxy-based materials containing exclusively nanosized filler particles. Epoxy microcomposites are defined as epoxy materials containing exclusively microsized filler particles, and epoxy micro+nano composites are materials containing both microsized and nanosized particles.

Recursion-based multiple changepoint detection in multiple linear regression and application to river streamflows

Abstract: [1] A large number of models in hydrology and climate sciences rely on multiple linear regression to explain the link between key variables. The relationship in the physical world may experiment sudden changes because of climatic, environmental, or anthropogenic perturbations. To deal with this issue, a Bayesian method of multiple changepoint detection in multiple linear regression is proposed in this paper. It is an adaptation of the recursion-based multiple changepoint method of Fearnhead (2005, 2006) to the classical multiple linear model. A new class of priors for the parameters of the multiple linear model is introduced, and useful formulas are derived that permit straightforward computation of the posterior distribution of the changepoints. The proposed method is numerically efficient and does not involve time consuming Monte-Carlo Markov Chain simulation as opposed to other Bayesian changepoint methods. It allows fast and straightforward simulation of the probability of each possible number of changepoints as well as the posterior probability distribution of each changepoint conditional on the number of changes. The approach is validated on simulated data sets and then compared to the methodology of Seidou et al. (2006) on two practical problems, as follows: (1) the changepoint detection in the multiple linear relationship between mean basin scale precipitation at different periods of the year and the summer-autumn flood peaks of the Broadback River located in Northern Quebec, Canada; and (b) the detection of trend variations in the streamflows of the Ogoki River located in the province of Ontario, Canada.