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.

Compressive strength and microstructure of assorted wastes incorporated geopolymer mortars: Effect of solution molarity

Abstract: This paper presents the solution molarity dependent microstructures and mechanical properties of multi-blend geopolymer mortars (GPMs). Geopolymer mortars were cured at ambient temperature under varying concentration (from 2 to 16 M) of sodium hydroxide (NH) solution. GPMs are by conducting mechanical tests such as compressive, split tensile and flexural strengths and characterised by microstructural studies, such as X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray spectroscopy (EDS). The effect of Na2O, H2O content, solution modulus (SiO2:Na2O) and Na2O:Al2O3 on GPMs strength were determined. The flow ability and setting time of such GPMs found to decrease linearly with increasing alkali concentration. Conversely, the GPMs comprehensive, split tensile and flexural strengths and the density are enhanced with increasing alkali concentration. Samples activated with 12 M NH solution are most strongly affected by silica dissolution. Furthermore, the ratio of (Na2O:Al2O3) was demonstrated to influence the compressive strength significantly and the (Na2O:Al2O3 = 0.84) presented the optimum strength.

Production of superhydrophobic polymer fibers with embedded particles using the electrospinning technique

Abstract: Superhydrophobic materials are currently used for their water-repelling, self-cleaning and anti-fouling properties but are also potentially attractive to prevent snow or ice accumulation on exposed structures. Using the electrospinning technique, polymer mats made of polystyrene and poly[tetrafluoroethylene-co-(vinylidene fluoride)-co-propylene] (PTVFP) were prepared. They were found to show highly hydrophobic properties, water contact angle (CA) between 130 and 150°, when a dual fiber–bead microstructure was observed. Superhydrophobicity, CA > 150°, was reached when PTVFP mats were electrospun from a polymer solution containing dispersed polytetrafluoroethylene (PTFE) nanoparticles. Using atomic force microscopy imaging, protruding nanosized asperities on fiber and bead surfaces were observed and this structure led to superhydrophobic properties. Materials prepared from a high-viscosity PTVFP/ethyl acetate solution with PTFE particles, 200 nm diameter and 8% (w/w), showed an 11.2% improvement in hydrophobicity, CA = 161°, compared to the materials obtained from a particle-free polymer solution (CA = 143°). Copyright © 2007 Society of Chemical Industry

Modeling of lightning incidence to tall structures. II. Application

Abstract: For pt.I see ibid., vol.9, no.1, p.162-71 (1994). The present paper comprises an extensive computer investigation of lightning incidence to tall masts, based on a theory presented in part I, for both flat and hilly regions. The investigation covers both downward negative lightning incidence and upward flash from tall masts under negative cloud. The factors investigated include: mast height, statistical distribution of the ground electric field, as well as mountain height and topology. Predicted lightning incidence and probability of upward flash are successfully verified against extensive field observations. >