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.

Care needs and economic consequences after acute ischemic stroke: the Erlangen Stroke Project

Abstract: The objective was to determine the functional outcome, location of care and economic consequences in the first 3 months after ischemic stroke. As part of the Erlangen Stroke Project, (ESPro) information was collected on patients suffering a first-ever ischemic stroke. Three months after the stroke, location of care, dependence on caregivers and function based on Barthel Index: poor (0-55), moderate (60-90) or good function (95-100) were recorded. Data about health services used were combined with cost estimates for Germany (2000 Euros, undiscounted). Of 491 patients hospitalized, 383 were alive 3 months afterwards, 79% residing in the community. The majority of patients with poor function (60%) were still in institutional care. Patients with good function typically accrued the lowest costs, whether in an institution (17 965) or not (11 032) compared with poorer function who were living in an institution (poor: 26 370; moderate: 28,121), or community (poor: 27,207; moderate: 19,350). Hospitalization and rehabilitation services were the major costs accrued at each level of function. Many patients were left requiring a substantial amount of care and the costs associated with providing institutional care has a major impact on the economic consequences of a stroke.

Improving power flow convergence by Newton Raphson with a Levenberg-Marquardt method

Abstract: This paper presents a comparative study of different techniques for improving the convergence of power flow by adjusting the Jacobian iteratively within the Newton Raphson method. These techniques can be used for improving the rate of convergence, increasing the region of convergence or just to find a power flow solution when traditional procedures may diverge or possibly oscillate until an iteration limit is reached even though a valid solution exists. Different techniques are first derived from an investigation of various schemes with the Newton process for the search of roots for a single variable function. The methods are then extended to the power flow problem. Comparisons of the region of convergence on a large power system are also presented to illustrate the effectiveness of the proposed methods.

Evaluation of the Actual Working Temperature of A Single-Chamber SOFC

Abstract: Single-chamber solid oxide fuel cell (SOFC) experiments have been carried out at temperatures below 900°C with methane-air mixtures. Our study confirms previous results obtained by Hibino and co-workers with conventional materials like for the cathode and a NiO-yttria-stabilized zirconia (YSZ) cermet for the anode. In addition, special attention has been paid both to the gas flow and to the actual operating temperatures. Platinum meshes and wires upon the electrodes would greatly influence their actual operating temperature and they have been systematically avoided for the working cells within this study. © 2004 The Electrochemical Society. All rights reserved.

Thoughts on power system flexibility quantification for the short-term horizon

Abstract: This paper reviews the notion of flexibility and applies it to the problem of power system adequacy of supply and reserve computations in the face of a class of input uncertainties. It first presents some definitions given to flexibility and flexibility indices in the power systems and process control industries. This is by no means a comprehensive review, but it does highlight some of the main ideas in the field. The notion of flexibility is applied to assess the quality of a solution strategy, based on some initial criterion for a given scenario, for example reliability, and then on its success in satisfying a set of scenarios. The paper then illustrates the use of a flexibility index borrowed from the process control literature to evaluate a solution strategy that provides balancing reserves to mitigate wind generation uncertainties. The paper concludes that flexibility can only be obtained at a cost and that it could prove itself to be a useful tool for the operator in an emerging technological environment.