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Mississauga, Canada

Founded in 1911, SNC-Lavalin Group Inc., a Montreal-based company, provides EPC and EPCM services in a variety of industry sectors, including mining and metallurgy, oil and gas, environment and water, infrastructure and clean power. In many cases, SNC-Lavalin combines these services with financing and operations and maintenance. Wikipedia.

Hasan N.,SNC - Lavalin
Practice Periodical on Structural Design and Construction | Year: 2015

Allowable bending fatigue stress is an important input for rail section design because of the nature of repeated loading on railways. The majority of rail failures have their origin in fatigue. In the American Railroad Engineering and Maintenance-of-Way Association (AREMA), there is only a fatigue test under the name of rolling load test for bonded joints; there are no fatigue tests for parent rail and welded joints. With respect to bonded joints, there is no known railroad or transit agency that uses plain bonded joints as an alternative to either flash butt weld (FBW) or alumino thermite weld (ATW) joints. A rail or weld should be able to resist at least 2 million stress cycle repetitions without developing any cracks. In this paper, allowable bending fatigue stress is formulated analytically with the nominal stress method (S-N). Marin's six modification factors are applied to the laboratory-determined fatigue limit to account for surface conditions, size, load, temperature, reliability, and shape. Then, Goodman's mean stress correction factor is applied to account for mean tensile stress in the rail. A brief literature review on the modification factors is included. The allowable bending fatigue stress is calculated and validated theoretically, then compared with the recommended AREMA value. Finally, the current AREMA formula and its recommended value for allowable bending fatigue stress are discussed. © 2014 American Society of Civil Engineers. Source

Bouzid A.-H.,Ecole de Technologie Superieure of Montreal | Nechache A.,SNC - Lavalin
International Journal of Pressure Vessels and Piping | Year: 2010

Bolted flange joints are prone to leakage when exposed to high temperature. In several cases, the root cause is relaxation that takes place as a result of material creep of the gasket, the bolt and the flange. One way to overcome this problem is to make the joint less stiff by introducing disc springs or the use of longer bolts with spacers. Although widely used, these two methods have no reliable analytical model that could be used to evaluate the exact number of washers or length of the bolts required to reduce relaxation to a minimum acceptable level. This paper describes an analytical model based on the flexibility and deflection interactions of the joint different elements including the axial stiffness of the flange and bolts, used to evaluate relaxation. The developed analytical flange model can accommodate either disc springs or longer bolts with spacer tubes to reduce the bolt load loss to a maximum acceptable value. This model is validated by comparison with the more accurate FEA findings. Calculation examples on a bolted flanged joint are presented to illustrate the suggested analytical calculation procedure. © 2010 Elsevier Ltd. Source

Bridger D.W.,SNC - Lavalin | Allen D.M.,Simon Fraser University
Canadian Geotechnical Journal | Year: 2010

A modelling study was carried out to evaluate the influence of aquifer heterogeneity, as represented by geologic layering, on heat transport and storage in an aquifer used for aquifer thermal energy storage (ATES). An existing ATES system in Agassiz, British Columbia, Canada, was used as a case study. The system consists of four production wells completed in an unconfined heterogeneous aquifer consisting of interbedded sands and gravels. An additional dump well was installed to provide for heat dissipation during the peak cooling periods. Three monitoring wells and the production wells were logged for temperature periodically within the first 1.5 years of operation. A three-dimensional groundwater flow and heat transport model was developed using FEFLOW. Simulation results indicate that heat and (or) cold energy moved preferentially in discrete zones within the aquifer or at least entered the wells over discrete intervals. Monitoring data support model results, but show that thermal storage was successfully achieved despite a significant cooling operation during the first year. © 2010 NRC Canada. Source

Younis L.B.,SNC - Lavalin
Journal of Porous Media | Year: 2010

The present work examines numerically the cross-flow and heat transfer from a bundle of staggered cylinders embedded in a porous medium. The effects of Reynolds number within the laminar flow regime, permeability, and thermal con-ductivity of the porous material on the fluid flow and heat transfer from the cylinders in the cross-flow are examined. Also, the results are compared with heat transfer from a cylinder embedded in a porous medium. Prandtl number is fixed to 1.0 for gases. It is found that the porous medium may enhance the rate of heat transfer if the permeability of the porous material is high, that is, the Darcy number is greater than 10-3 Also, increasing the thermal conductivity of the porous material has a positive effect on enhancing the rate of heat transfer from the single column of cylinders or from the cylinders in the first column of a multicolumn heat exchanger. However, the porous medium may have a negative effect on the rate of heat transfer from downstream cylinders, where the temperature gradient decreases because of the enhanced rate of heat transfer from the upstream cylinders. © 2010 by Begell House, Inc. Source

Kalantari A.,McGill University | Restrepo J.F.,SNC - Lavalin | Galiana F.D.,McGill University
IEEE Transactions on Power Systems | Year: 2013

We present a novel approach to the security-constrained unit commitment (SCUC) with uncertain wind power generation. The goal is to solve the problem considering multiple stochastic wind power scenarios but while significantly reducing the computational burden associated with the calculation of the reserve deployment for each scenario. The method is called reduced SCUC or R-SCUC and is based on the notion of loadability set, that is, the set of residual demand scenarios that can be met by the transmission and reserve capability of a given power system at any specific hour. The key is to project all feasible generation and demand vectors onto the demand space and reformulate the SCUC within this loadability set rather than on the larger set of generation and demand. The accuracy and performance of R-SCUC were gauged and compared to SCUC via a three-region multi-unit system and by the IEEE 24-bus reliability test system with multiple units. Simulations support the accuracy and superior computational performance of R-SCUC. © 2012 IEEE. Source

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