Erchiqui F.,University of Quebec at Abitibi - Temiscamingue
Drying Technology | Year: 2013
In this article, the frequency effect on the applicability of Beer-Lambert's law for thawing frozen wood using the microwave energy was analyzed. To this end, we use Maxwell's equations to determine the absorbed power and characterize the critical slab thickness Lcrit of three Canadian eastern wood species: trembling aspen (Populus tremuloides Michx), yellow birch (Betula alleghaniensis), and sugar maple (Acer saccharum). The critical thickness Lcrit above which the Beer-Lambert law is valid is estimated as a hyperbolic function in the frequency domain: Lcrit = m/fn (f is the frequency of microwave radiation; m and n are adjustment constants). The nonlinear heat conduction problem involving phase changes such as wood freezing is solved by a three-dimensional volumetric specific enthalpy-based finite element method. The dielectric and thermophysical properties are functions of temperature and moisture content. The specific volumetric enthalpy approach is validated by experimental testing. For instance, we studied the frequency effect on the thawing of frozen trembling aspen wood. © 2013 Copyright Taylor and Francis Group, LLC.
Ben Mabrouk I.,University of Quebec at Outaouais |
Talbi L.,University of Quebec at Outaouais |
Nedil M.,University of Quebec at Abitibi - Temiscamingue |
Hettak K.,Communications Research Center Canada
IEEE Transactions on Antennas and Propagation | Year: 2012
Multiple input multiple output-ultrawide band (MIMO-UWB) systems are experimentally evaluated for underground mine high-speed radio communications. Measurement campaigns using two different antenna configurations have been made in an underground gold mine. Furthermore, two scenarios, which are the line of sight (LoS) and the non-LoS (NLoS), i.e., taking into account the mining machinery effect, are distinguished and studied separately. In fact, the channel is characterized in terms of coherence bandwidth, path loss, shadowing, channel correlation, and capacity. Results reveal how antenna array configuration affects main channel parameters and suggest that mining machinery presence substantially affects both received power and time dispersion parameters within the underground mine and should, therefore, be considered when assessing the performance of in-gallery wireless systems. Moreover, it is shown that the MIMO-UWB takes benefit of the large spreading bandwidth and the multipath propagation environment to increase the channel capacity. © 1963-2012 IEEE.
Yilmaz E.,University of Quebec at Abitibi - Temiscamingue
Gospodarka Surowcami Mineralnymi / Mineral Resources Management | Year: 2011
A large amount of solid and liquid wastes produced by mines and mills each year needs to be managed and minimized by alternative disposal methods like paste and dry stack. Increasingly strict environmental legislation and cost competitiveness also dictate the utilization of technically suitable, economically viable, environmentally acceptable, and socially responsible techniques. This paper reviews some of these techniques that could potentially reduce large volumes of mine wastes (with a focus on mine tailings and waste rocks) without causing significant environmental hazards. The new emerging techniques such as environmental desulphurization, covers built with sulphide-free tailings, co-disposal of tailings and waste rocks, geotextile tube dewatering, and use of tailings in the cement production and road construction for both industrial and environmental purposes are discussed in terms of waste minimization. The existing methods and approaches for efficient waste treatment and disposal are also discussed in this review paper.
Fouad E.,University of Quebec at Abitibi - Temiscamingue
Chemical Engineering Science | Year: 2013
This paper addresses the thawing of frozen wood by micro wave. We consider two power formulations for the absorbed energy: the correct power dissipation computed from Maxwell's equations and Lambert's power law equation. The critical thickness above which the two formulations are approximately equivalent is characterized as an exponential-hyperbolic function of frequency and temperature. Four Canadian eastern wood species are used: trembling aspen ( Populus tremuloides), yellow birch ( Betula alleghaniensis), white birch ( Betula paperyfera), and sugar maple ( Acer saccharum). The nonlinear heat conduction problem involving phase changes such as wood freezing is solved by a volumetric specific enthalpy-based finite element method. Dielectric and thermophysical properties are functions of temperature and moisture content. For illustration purposes, we considered the thawing of frozen trembling aspen wood. © 2013 Elsevier Ltd.
Badri A.,University of Quebec |
Nadeau S.,University of Quebec |
Gbodossou A.,University of Quebec at Abitibi - Temiscamingue
Accident Analysis and Prevention | Year: 2012
Excluding occupational health and safety (OHS) from project management is no longer acceptable. Numerous industrial accidents have exposed the ineffectiveness of conventional risk evaluation methods as well as negligence of risk factors having major impact on the health and safety of workers and nearby residents. Lack of reliable and complete evaluations from the beginning of a project generates bad decisions that could end up threatening the very existence of an organization. This article supports a systematic approach to the evaluation of OHS risks and proposes a new procedure based on the number of risk factors identified and their relative significance. A new concept called risk factor concentration along with weighting of risk factor categories as contributors to undesirable events are used in the analytical hierarchy process multi-criteria comparison model with Expert Choice © software. A case study is used to illustrate the various steps of the risk evaluation approach and the quick and simple integration of OHS at an early stage of a project. The approach allows continual reassessment of criteria over the course of the project or when new data are acquired. It was thus possible to differentiate the OHS risks from the risk of drop in quality in the case of the factory expansion project. © 2011 Elsevier Ltd.