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Fortin, Yves

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Fortin

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Yves

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Université Laval. Département des sciences du bois et de la forêt

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ncf10126795

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Voici les éléments 1 - 8 sur 8
  • PublicationAccès libre
    Shrinkage variation in Japanese larch (Larix kaempferi, [Lamb.]) progenies/provenances trials in Eastern Canada
    (Taylor & Francis, 2017-05-19) Caceres Cuadros, Claudia; Fortin, Yves; Hernández, Roger
    Twelve-year-old Japanese larch (Larix kaempferi [Lamb.]Carr.) trees of 20 different progenies and/or provenances were sampled at one site in the Mauricie region of Quebec. Two standard samples were obtained at breast height and closer to the bark from each tree. Partial and total radial, tangential, and volumetric shrinkages, and tangential/radial (T/R) shrinkage ratios were assessed. All of these variables were significantly affected by the progeny/provenance. Drying defects are one of the main reasons for downgrading larch lumber; thus, T/R shrinkage ratio was considered for the selection of progenies/provenances for lumber production purposes. Lowest partial and total T/R shrinkage ratios were obtained with progenies/provenances 8964, 8904, 8962, 8957, 8907, 8927, 7283, and 7795. Among them, lowest partial and total tangential, radial, and volumetric shrinkages were found in progenies/provenances 8964, 8962, and 8907 as well. Other physico-chemical (mechanical properties, density, extractive content) and silvicultural (growth rate) attributes should also be taken into consideration for an adequate selection of progenies/provenances according to the specific final utilization.
  • PublicationRestreint
    Moisture content–water potential relationship of sugar maple and white spruce wood from green to dry conditions
    (Society of Wood Science and Technology, 1999-01-31) Defo, Maurice.; Cloutier, Alain; Fortin, Yves
    The moisture content-water potential relationship was determined at 40°C and 60°C for sugar maple (Acer saccharum Marsh.) sapwood and at 60°C for white spruce (Picea glauca (Moench.) Voss.) heartwood from green to dry conditions. The pressure membrane technique was used for high moisture contents and equilibration over salt solutions for low moisture contents. The results show that at high moisture contents, the equilibrium moisture contents obtained from the green condition are lower than those obtained from full saturation (boundary desorption). It is recommended that the sorption history must be taken into account when modeling wood drying. Water potential at a given moisture content increases with temperature. There is a characteristic plateau in the green moisture content-water potential relationship obtained for sugar maple at water potentials between -2,000 and -6,000 J kg-1, which can be attributed to its heterogeneous capillary structure. The maximum concentration of effective pore radius occurs at 0.02 μm in the case of sugar maple, corresponding to the size of the pit membrane openings.
  • PublicationRestreint
    Determination of the effective water conductivity of red pine sapwood
    (Springer, 2000-01-31) Cloutier, Alain; Tremblay, Carl; Fortin, Yves
    The instantaneous profile method was used to establish the boundary desorption curve of the effective water conductivity function of red pine (Pinus resinosa Ait.) sapwood in the radial and tangential directions from nearly saturated to dry conditions at 18, 56 and 85 °C. The results obtained demonstrate that the effective water conductivity is a function of moisture content, temperature, and direction of flow. The effective water conductivity increases by several orders of magnitude (104–105) as moisture content increases from dry to nearly saturated conditions at a given temperature. The effective water conductivity also increases by a factor varying between 10 and 50 as temperature rises from 18 to 85 °C in the moisture content range considered. The variation of the moisture content–water potential relationship with temperature can explain part of the temperature effect. The effective water conductivity was generally higher in the radial direction than in the tangential direction in a ratio varying from about 1/1 to 3/1 depending on moisture content and temperature. Finally, the flux–gradient relationships obtained at given moisture contents were found to be linear, confirming the validity of using a moisture flux equation considering the water potential gradient as the driving force for the experimental conditions considered in the present work. The knowledge of the effective water conductivity function and of the moisture content–water potential relationship allows the utilization of a two-dimensional model of moisture movement in wood during drying using the gradient in water potential as the driving force for drying at temperatures up to 85 °C.
  • PublicationRestreint
    Determination of the effective water conductivity of sugar maple sapwood and white spruce heartwood under vacuum
    (Society of Wood Science and Technology, 1999-10-02) Defo, Maurice.; Cloutier, Alain; Fortin, Yves
    A macroscopic approach based on the water potential concept is proposed to represent the movement of water in wood during continuous vacuum drying. In order to solve the flow equation, the effective water conductivity under vacuum must be known. A new apparatus is proposed to determine this moisture transport coefficient based on the instantaneous profile method, where moisture content profiles are established at different drying times, making possible the measurement of the moisture flux and driving force at a given position. One-dimensional moisture flow measurements were conducted through two sides of a cubic wood specimén under constant temperature and absolute pressure. The effective water conductivity function was established from green to dry conditions at 60°C in the radial and tangential directions; at 8, 13, and 18 kPa for sugar maple sapwood; and at 8 kPa for white spruce heartwood. The results show that the effective water conductivity decreases exponentially from green conditions to about 35% moisture content for sugar maple. Beyond this point, the effective water conductivity decreases more gradually with a decrease in moisture content for both sugar maple and white spruce. The effective water conductivity is generally higher in radial than in tangential direction for both species. The results obtained for sugar maple show that the effective water conductivity increases significantly as the pressure decreases. The effect of pressure can be explained by the contribution of the apparent gas permeability. The contribution of the pressure potential to the total water potential can be neglected below fiber saturation point. The flux-gradient relationships obtained at given moisture contents are linear, confirming the validity of the flow equation based on water potential used in the present work.
  • PublicationAccès libre
    Phenotypic and genotypic correlations for wood properties of hybrid poplar clones of southern Quebec
    (Molecular Diversity Preservation International, 2018-03-15) Huda, Azmul; Périnet, Pierre; Cloutier, Alain; Koubaa, Ahmed; Fortin, Yves; Hernández, Roger
    This study aims to understand the phenotypic and genotypic correlations among wood anatomical, physical, and mechanical properties of hybrid poplar clones. Samples were taken from seven clones grown on three sites in Southern Quebec, Canada. Five trees per clone were randomly sampled from each site to measure anatomical (fiber length, fiber proportion, vessel proportion, fiber wall thickness, tension wood), physical (basic density, volumetric, longitudinal, tangential, and radial shrinkage), and mechanical wood properties (flexural modulus of elasticity (MOE), modulus of rupture (MOR), ultimate crushing strength parallel to the grain). The observed phenotypic and genotypic correlations between these wood properties were moderate to strong, except for fiber length and vessel proportion. Genotypic correlations for all wood properties were higher than for corresponding phenotypic correlations. Furthermore, fiber length showed weak correlations, whereas, vessel proportion showed strongly negative correlations with all other properties. Strong correlations were also found among fiber proportion, fiber wall thickness, basic density, and mechanical properties. Furthermore, results from this study show close genotypic and phenotypic correlations between fiber proportion, fiber wall thickness, and wood density, which consequently affect the mechanical performance of wood products. These findings indicate that there is a substantial opportunity to improve wood quality by selecting several wood properties for different end uses.
  • PublicationRestreint
    Modeling vacuum-contact drying of wood : the water potential approach
    (2007-05-10) Defo, Maurice.; Cloutier, Alain; Fortin, Yves
    A two-dimensional mathematical model for vacuum-contact drying of wood is presented. The moisture and heat equations are based on the water potential concept whereas the pressure equation is formulated considering unsteady state conservation equation of dry air. Most of the model parameters were determined during independent experiments. The set of equations is then solved in a coupled form using the finite element method. The validation of the model is performed using experimental results obtained during vacuum-contact drying of sugar maple sapwood. The experimental and calculated data are in good agreement. Nevertheless, some discrepancies are observed which can be attributed to the boundary conditions used and to the fact that heat transfer by convection was neglected.
  • PublicationAccès libre
    Variation of the physical and mechanical properties of hybrid poplar clones
    (Dept. of Wood and Paper Science College of Natural Resources North Carolina State University, 2014-01-01) Huda, Azmul; Cloutier, Alain; Koubaa, Ahmed; Fortin, Yves; Hernández, Roger
    The physical and mechanical properties of poplar clones largely determine their suitability for various end-uses, especially for high value-added applications. The main objective of this study was to determine the clonal variation of selected physical and mechanical properties of seven hybrid poplar clones grown at three sites in southern Quebec, Canada. Five trees per clone were randomly sampled from each site for wood properties measurement. Site had a significant effect on all measured properties except radial shrinkage. All properties of hybrid poplar wood showed significant interclonal variation, indicating the possibility of identifying clones with superior wood properties, especially for density, flexural modulus of rupture, and ultimate crushing strength. High heritability values for the studied properties indicated that these properties are under moderate to high genetic control. The genetic gain for these wood properties ranged from 2.0% to 13.5%.
  • PublicationRestreint
    Experimental determination of the convective heat and mass transfer coefficients for wood drying
    (Springer., 2000-01-31) Cloutier, Alain; Fortin, Yves
    The knowledge of the convective heat and mass transfer coefficients is required for the characterization of the boundary conditions of the heat and mass transfer equations of a wood drying model based on water potential. A new experimental method for the determination of the convective mass transfer coefficient is presented. This method is based on the measurement of the moisture content, and indirectly the water potential, at the surface of a wood specimen at different drying times. Drying experiments were performed on red pine (Pinus resinosa Ait.) sapwood from nearly saturated to dry conditions at 56 °C, 52% relative humidity and air velocities of 1.0, 2.5 and 5.0 m s−1. The results show that the convective mass transfer coefficient is constant until the wood surface moisture content reaches about 80% and then decreases more or less gradually as the moisture content decreases further. The convective mass transfer coefficient increases with air velocity. A regression analysis shows that there is no significant improvement in considering the water potential gradient near the wood surface when the difference in water potential between the surface and the surrounding air (ψs − ψ∞) is used to determine the convective mass flux at the surface. Also, ψs − ψ∞ is more appropriate than the water vapour pressure difference (pvs − pv∞) as the responsible driving force of the moisture flux leaving the wood surface. The convective heat transfer coefficient was determined during the same experiments. A plateau is observed at high values of moisture content corresponding to the constant drying rate period.